Introduction
Shaped cutters are a tool whose cutting edges have a shape that depends on the profile shape of the workpiece.
Shaped cutters work in difficult conditions, since all cutting edges simultaneously engage in cutting and create high cutting forces. Their use does not require highly qualified workers, and the accuracy of the processed parts is ensured by the design of the cutter itself. Carefully calculated and precisely manufactured shaped cutters, when installed correctly on machines, ensure high productivity, precise shape and dimensions of the processed parts.
The accuracy of manufacturing parts using shaped cutters can be achieved up to 9-12 accuracy grades.
Round shaped cutters are used for turning external and internal surfaces, and prismatic ones only for external ones. The main advantages of round shaped cutters are the ease of their manufacture and a large number of regrinds compared to prismatic cutters. The cutters are fixed on a mandrel and secured against rotation using corrugations made on one of the ends.
More often, corrugations are made on a special ring with a pin, which is part of the holder for attaching the cutter to the machine. In this case, a hole for the pin is drilled at the cutter.
The length of the profile of the shaped cutter is taken to be slightly greater than the length of the workpiece. The permissible length of the cutter profile L p when fastening the workpiece in the chuck is limited.
Round shape cutter design
Shaped cutters are an expensive and complex tool. For a round cutter, only the cutter itself is made of high-speed steel, and the holder on which it is mounted is made of structural steel. To prevent the cutter from rotating on the holder, a serrated corrugated surface is made.
For the production of round cutters, it is advisable to use multi-purpose CNC machines.
When processing on these machines, the ease of production of even the most complex shaped profiles is noted.
The main structural elements of a shaped round cutter that need to be determined are:
outer diameter of the cutter;
hole diameter;
shaped cutter profile;
cutter length.
The outer diameter of the cutter is set taking into account:
product profile height,
distance required for chip removal L,
minimum value of the cutter wall size M.
Figure 1. Standard size of shaped surface
Part dimensions: D - 42 mm; D 1 - 45 mm; l 1 = 3 mm; l 2 -- 18 mm; l 3 = 33 mm;
L =40 mm; f = 0.5 mm.
Processed material - steel 20XG
We take the length of the cutter to be increased by 4 mm compared to the length of the part to compensate for the inaccuracy of installing the rod relative to the cutter.
On the surface in contact with the bar, we make an undercut angle to prevent the side surface of the cutter from rubbing against the bar.
To facilitate precise installation of the cutter at the height of the center of the product, notches should be made on the body of the cutter. For ease of sharpening, it is recommended to place a control circular mark on the cutter, the radius of which is equal to hp.
Tolerances for the manufacturing accuracy of all linear dimensions of the cutter are not directly specified. Tolerances are usually set for the manufacture of all template sizes for a given cutter, and the profile of the cutter is measured by the template. Tolerances for template manufacturing are accepted in the range of 0.01-0.02mm.
Choice of material for cutting parts.
We choose high-speed steel R6M5.
Characteristics of R6M5.
Steel R6M5 has mainly replaced steel R18, R12 and R9 and has found application in the processing of non-ferrous alloys, cast irons, carbon and alloy steels, as well as some heat-resistant and corrosion-resistant steels.
The strength of this material is satisfactory. Increased wear resistance at low and medium cutting speeds. This material has a wide range of quenching temperatures.
Sandability is satisfactory.
R6M5 steel is used for the production of all types of cutting tools when processing carbon alloy structural steels; Preferably for the manufacture of thread-cutting tools, as well as tools that work with shock loads.
Chemical composition of R6M5 steel:
The hardness of the R6M5 material after annealing is HB 10 -1 = 255 MPa.
Geometry of the shaped cutter.
A shaped cutter, just like any other cutter, must be equipped with appropriate rear and rake angles so that the chip removal process takes place under sufficiently favorable conditions.
The geometric parameters of the cutting part - angles b and d - are set at the base point (or on the base line) of the cutting edge in the n plane, perpendicular to the base of the cutter attachment. Point A, which is furthest from the mounting base, is taken as the base point.
Figure 2. Geometric parameters of the cutting part
The front angle of a radial round cutter is made during its manufacture, placing the front surface at a distance h from the cutter axis, and the rear angle is obtained by setting the cutter axis above the axis of the part by the value h p.:
h p = RХsin(b)
where R = D/2 is the radius of the cutter at the base point (D is the maximum diameter of the cutter).
The value of the anterior angles of radial incisors is assigned according to the table. 5 depending on the material being processed and the material of the cutter.
The clearance angle of the cutting edge of the cutter depends on the shape of the shaped cutter and its type; for round shaped cutters, the clearance angle is selected within the range of 10 0 -15 0. For calculations we will take 15 0.
The given values of the back and front angles refer only to the outer points of the cutter profile. As the points under consideration approach the center of the round cutter, the rear angle continuously increases, and the rake angle decreases.
Calculation of shaped cutter
The profile of the shaped cutter, as a rule, does not coincide with the profile of the workpiece, which requires adjustment of the cutter profile.
To do this, determine the dimensions of the normal section for prismatic and axial sections for round cutters.
The profile of a shaped cutter is adjusted in two ways:
graphic;
analytical;
Graphic methods provide the greatest accuracy; at the same time, they are simple and acceptable when adjusting the profile of cutters with simple configurations, with low accuracy requirements, and for approximate determination of the profile of complex and precise shaped cutters. All of them are based on finding the natural size of a flat figure, determined by the normal or axial section of the shaped cutter. In practice, the profile of a shaped cutter is adjusted using an analytical method that ensures high accuracy.
When the rear and rake angles are equal to 0, the profile of the cutter will exactly coincide with the profile of the part.
In our case, the angles do not equal 0, in this case you can notice that the profile of the cutter changes compared to the profile of the part, all dimensions of the profile, measured perpendicular to the axis of the part, change on the cutter.
Let us determine the cutting edge profile for our cutter in two ways and compare them.
First method: Graphic,
Second method: Analytical.
Graphic calculation of cutter profile
Profiling comes down to the following. Characteristic points 1, 2, 3... of the horizontal projection of the part are transferred to the horizontal axis of the vertical projection of the part, and then, with radii described from the center of the vertical projection of the part, are transferred to the mark of the front surface of the cutter. This achieves correction from the presence of the anterior angle. The resulting points are transferred from the mark of the front surface with radii described from the center of the cutter to the horizontal axis of its vertical projection. As a result of this transfer, a correction is made for the presence of a back angle. The resulting points are lowered down until they intersect with horizontal lines drawn from the characteristic points of the horizontal projection of the part.
In Fig. 4, in addition to profiling, additional cutting edges of the cutter are given, the dimensions of which can be taken into account when designing its design: S 1 - cutting edge that prepares for cutting the part from the workpiece (usually a rod); its top should not protrude beyond the working profile of the cutter, i.e. t - should be less than (or equal to) t max. In this case, the width of the groove for cutting should be 0.5... 1 mm wider than the length of the main cutting edge of the cutting tool. The angle q must be at least 15°.
An additional cutting edge S 2 is required for chamfering or trimming a part; S 5 = 1...2 mm - overlap; S 4 = 2...3 mm - strengthening part.
Thus, the length of the cutter
L R = l d + S 2 + S 4
where l d is the length of the part.
L p = 40 + 15 + 2 = 57 mm
Figure 4. Graphic method for profiling a cutter with sharpening at an angle r
The diameter of the round shaped cutter is determined graphically. Maximum depth of processed profile
d min, d max - the largest and smallest diameters of the profile of the workpiece.
According to the greatest depth of the processed profile according to the table. 3 we find
D = 60 mm, R 1 = 17 mm.
where, R= D/2 is the radius of the cutter at the base point (D is the maximum diameter of the cutter).
To obtain the rear angle of a round shaped cutter, its apex in operation is set below the axis of the cutter at a distance h.
Figure 5. Determining the clearance angles of the form cutter
We calculate the sharpening height of the shaped cutter with a base point relative to the axis of the part:
h p =17 * sin25=7.1 mm
The shaped contour is divided into separate sections, the base points characterizing the ends of the sections are designated by numbers and the coordinates of all base points are determined, i.e. Table 1 is compiled (see Figure 5).
It is advisable to arrange the base points so that they have the same radii r in pairs, which reduces the amount of correction calculations. Unknown coordinates of points are determined by solving right triangles. For example: the size l i is set, after that the radius of the point r 1 is determined, and then, having the radius, the size l i ” is obtained in a similar way. The accuracy of calculating the coordinates of the workpiece points is 0.01 mm.
Since a shaped cutter usually must be calculated over a number of nodal points, for convenience the calculations can be presented in the form of a table
Table 1
Analytical calculation of the profile of a shaped cutter
Solving elementary geometric problems, the number of characteristic points from which we determine the radii of the profile points of the part, as in the geometric method - 8.
Let us denote by numbers 1,2,...., i conditionally the points of a given profile, the radii r 1 , r 2 .... of nodal points and the distance along the axis between them l 21 .......l i1 are determined from the part drawing and are summarized in Table 1. Let point 1 be located at the height of the center of rotation of the part (base point). Through point 1 we draw the front surface of the cutter at an angle r 1. Due to the inclination of the front surface, the remaining node points (2, 3, ..., i) are located below the center of rotation of the part.
To calculate the profile of round and prismatic shaped cutters, it is necessary to determine the distances C i1 along the front face from point i to point 1.
Where r 1, r i are the radii of the base and i-th node points, respectively.
Consequently, the value of C i1 is not related to the structural shape of the cutters, i.e. the formula is valid for both prismatic and round cutters.
Determine the radius R i of the cutters for external processing:
where r 1, b 1 - front and rear angles for base point 1;
We determine the distance of the profile depth in the axial section of the round shaped cutter:
t 2 =30-29.5=0.5 mm
t 3 =30-29.5=0.5 mm
t 4 =30-26=4 mm
t 5 =30-24.8=5.2 mm
t 6 =30-26=4 mm
t 7 =30-29.5=0.5 mm
t 8 =30-29.5=0.5 mm
Let's compare the cutter sizes obtained by two methods:
Table 2.
Thus, the maximum discrepancy between the two methods was 1.163%. By comparing these two methods for calculating the profile of a shaped cutter, we determine that the analytical method is the most accurate.
The error is not large, so for small-scale production you can use the graphical method.
Designing a template and counter-pattern
Based on the results of the correction calculation, a template profile is constructed to control the accuracy of the profile of the shaped surface of the cutter after grinding, and a counter template to control the profiles of the grinding wheel for processing the cutter profile. To do this, a coordinate line is drawn through the base point parallel to the axis, from which the calculated values of the cutter profile height at characteristic points DR i are plotted. The axial dimensions of the cutter profile with an axis parallel to the axis of the part are equal to the axial dimensions of the part.
Curvilinear sections of the profile are specified in the form of an arc of radius r, the value of which is determined using the coordinates of three characteristic points located on the curved section, or the coordinates of a number of points through which the curve passes.
Profile manufacturing accuracy ±0.01. To facilitate grinding along the profile, a chamfer is made at an angle of 30°. Template material - steel 20ХГ, hardness HRC 58...62.
A round shaped cutter is a body of revolution in which an angular groove is cut to create a front plane and space for chip flow. The axis of the cutter is set above the axis of the part, so positive clearance angles are created on the shaped cutting edge
Round cutters are more technologically advanced to manufacture and allow a greater number of sharpenings. These cutters have ring and helical components. The material for round cutters is predominantly high-speed steel. To secure round shaped cutters into a holder, the end surfaces of these cutters are provided with corrugations, holes for a pin or grooves at the end. The design and overall dimensions of shaped cutters can be selected depending on the greatest depth of the profile of the part being manufactured according to the tables.
Exercise
Design a round shaped cutter for processing a workpiece from a bar with a diameter of D with the preparation of a groove for subsequent cutting.
Where D zag =80 mm, d 1 =67, d 2 =70, d 3 =78, d 4 =72, l 1 =3, l 2 =18, l 3 =30, l 4 =45
Dimensional accuracy h12±T14\2
Material LS 63-3 sigma b =350 MPa
Fig.1. Part sketch
Analytical (correction) calculation of cutter profile
1. DESIGN OF A SHAPED CUTTER
1.1 Selection of tool material for the cutting part
According to the table 2.9 for the cutting part of the cutter we select high-speed steel R6M5.
1.2 Choice of cutter design
According to their shape and design, shaped cutters are divided into round, prismatic and rod. Round cutters are more technologically advanced to manufacture and allow a large number of regrinds, therefore, to process a given part, we select a round cutter with ring generatrices. To secure the cutter in the holder, the end surfaces are equipped with holes for the pin.
1.3 Calculation of shaped cutter
Dmax=80 mm – the largest diametrical dimension of the part. Dmin=62.76 mm – the smallest diametrical size of the part. The greatest depth of the part profile is tmax=8.68 mm.
1.2 Determination of design parameters of the part profile
d calc. = d max - , where d calc. – maximum diameter taking into account tolerance, T – diameter tolerance.
| d calc.1 = 62.76- =62.635; | r calc.1 = =31.31; |
| d calc.2 = 67-66.875; | r calc.2 = 33.43; |
| d calc.3 = 70- =69.875; | r calc.3 = 34.93; |
| d calc.4 = 71.89- =71.765; | r calc.4 =35.88; |
| d calc.5 = 74.32- =74.195; | r calc.5 = 37.11; |
| d calc.6 = 76.35- =76.225; | r calc. 6 = 38.11; |
| d calc.7 = 78- =77.875; | r calc.7 = 38.93; |
| d calc.8 = 76.58- =76.455; | r calc.8 = 38.22; |
| d calc.9 = 75- =74.875; | r calc.9 = 37.43; |
| d calc.10 = 73.57- =73.435; | r calc.10 = 36.71; |
| d calc.11 = 72- =71.875; | r calc.11 = 35.93; |
| d calc.12 =d calc.13 = 69- =68.878; | r dis12 =r dis13 =34.43 |
| d ras14 =d ras15 =80- =79.875 | r dis14 =r dis15 =39.93 |
1.3 Determine the maximum profile depth of the workpiece being processed: t = = =8.6825mm;
Using the reference table for shaped disc cutters with end grooves, we determine based on the depth of the profile:
Cutter diameter – 40mm; diameter of the mounting hole is 13mm.
Since the width of this shaped cutter is more than 40mm, we will use a two-support fastening Fig. 1 to ensure increased structural rigidity.
Number of teeth of end corrugations: Z = 34.
Number of end teeth of the cutter: Z = 32.
Rake angle: γ = 5°; relief angle: α = 0°.
Diameter of the collar with end teeth: db = 1.5d = 1.5×13=19.5 mm, where d is the diameter of the mounting hole.
Bead length: l b = 3mm.
1 – body; 2 – screw; 3 – nut; 4 – cutter; 5 – bolt; 6 – lever; 7 – plug
Fig.1  |  |
Cutter width: B = l d +l extra +10, where l extra is the width of the additional blade for making a groove for cutting the finished part l extra = 5mm.
B = 80+5+10=95mm.
Length of the hole to be ground:
l 1 = 0.25(B – l additional) = 0.25(80-5) = 18.75mm
1.4 Corrective calculation of the profile of a round shaped cutter during its normal installation on the machine.
Sum of front and rear angles: ε = γ+α = 5°
Distance from the plane of the front surface to the axis of the cutter:
Cutter installation height
H = R 1 sinε = 38.93×sin5° = 3.39 mm
Distance from the plane of the front surface to the axis of the workpiece:
m = r 1 sinγ = 31.31×sin5° = 2.79 mm
Distance A 1 according to the design scheme:
A 1 =r 1 cosγ = 31.31×cos20° = 29.421 mm
Front angle at point i: sinγ i =
| sinγ 1 = = 0.0892 | γ 1 =4.25 | cosγ 1 =0.9511 | |
| sinγ 2 = 0.0839 | γ 2 =4.98 | cosγ 2 =0.9562 | |
| sinγ 3 = 0.0789 | γ 3 = 3.17 | cosγ 3 =0.9626 | |
| sinγ 4 = 0.0777 | γ 4 =3.14 | cosγ 4 =0.9690 | |
| sinγ 5 = 0.0751 | γ 5 = 4.05 | cosγ 5 =0.9729 | |
| Sinγ 6 = 0.0732 | γ 6 = 4.20 | Cosγ 6 =0.9802 | |
| Sinγ 7 =0.0716 | γ 7 =2.73 | Cosγ 7 =0.9790 | |
| Sinγ 8 =0.0729 | γ 8 =3.053 | Cosγ 8 =0.9750 | |
| Sinγ 9 =0.0745 | γ 9 =3.62 | Cosγ 9 =0.96766 | |
| Sinγ 10 =0.0761 | γ 10 =3.82 | cosγ 10 =0.93748 | |
| sinγ 11 =0.0776 | γ 11 =4.2 | cosγ 1 1 =0.98279 | |
| sinγ 12.13 =0.081 | γ 12.13 =1.45 | cosγ 12, 13 =0.93748 | |
| sinγ 14.15 =0.0698 | γ 14.15 =4.98 | cosγ 14, 15 =0.96766 | |
Distance A i according to the design scheme A i =r i *cosγ i
A 2 = r 2 cosγ 2 = 31.965766
A 5 = 
33.185619
A 10 =34.4627023
A 11 =35.3116447
A 12.13 =32.2774364
A 14.15 =38.6386638
| |
Distance C i according to the design scheme, mm: C i = A i – A 1
C 2 = 2.2745766
C 12.13 =2.8564
Distance B 1 according to the design diagram, mm: B 1 =R 1 cosε=39.5×cos30° = 34.208mm
B i = B 1 – C i
B 2 = B 1 – C 2 = 39.964mm
B 3 = B 1 – C 3 = 30.006
B 4 = B 1 – C 4 = 28.974
B 12.13 =31.358
B 14.15 =24.991
Distance angle at point i: tgε i =
The order of setting the axial dimensions of the profile on the template and counter-template should be kept the same as on the shaped cutter. Tolerances on the vertical and axial dimensions of the template profile should be 1.5...2 times less than on the dimensions of the cutter, and tolerances on the dimensions of the counter template profile should be 1.5...2 times less than on the dimensions of the template.
 |
Broach design
Initial data for design
Hole diameter D o = 38.65mm.
Diameter of the finished hole D=40 H9 +0.030 mm.
Hole length l= 80 mm.
Surface roughness Ra= 2.5 µm.
Part material: SCh20.
Mechanical properties:
strength σ c ≈ 200 MPa;
hardness HB=220
Machine model 7A534.
Traction force Р с = 250000 N.
Longest stroke length l r . k. = 1600 mm.
broaching broaching calibrating tooth
The designed broach is designed for processing a round hole with manufacturing accuracy of 9th grade and surface roughness Ra= 2.5 µm. The required hole in SCh20 can be obtained by broaches working according to a group or profile cutting pattern.
The material of the working part is accepted R6M5 GOST 19265-73.
We will decide the question of a specific cutting pattern based on the shortest length of the working part of the broach.
To ensure high broaching strength, we adopt a one-piece design of the tool. Material of the tail part of the broach is alloyed tool steel 40Xσ B ≈ 250 MPa
P xv =[Ϭ] p *F ox
F ox = 0.25*π*D ox 2 =0.25*3.14*42 2 =1385.5 mm 2
P xv =200*1385.5=277100 N
Geometric parameters of broach teeth
tooth rake angle γ = 10;
rear angle of roughing and transition teeth α 0 = 3°;
rear angle of finishing teeth α h = 3°;
rear angle of calibration teeth α k = 1°.
Calculation of main structural elements
We set the speed that the machine can provide:
Rough tooth lift Sz = 0.05 mm.
choose a tooth shape with a radius back. Preliminary pitch of cutting teeth for broaching variable cutting.
t=(1.25....1.5)L zag 0.5 =(1.25....1.5)*80 0.5 =10mm
Flute fill factor
Flute depth required to fill the flute
h= 0.5 = 0.5 =2mm
We take the depth of the chip flute h = 4 mm; and the pitch of the cutting teeth is assumed to be t=12.
We take the remaining elements from the table 3=4 mm
r=3mm R=7mm
Number of simultaneously working teeth.
Z slave =(lzag/t)+1=80/10=9
We accept the nearest smaller number Z slave =9
The condition 3≤ Z slave ≤8 is not satisfied. But when processing cast iron, coolant is not used, so the maximum Z slave can be increased.
As P additional we accept the smallest of 3 possible restrictions: permissible force in the shank; permissible force on the first tooth; permissible force according to the technical characteristics of the machine
: R oh; P01; Q.
P 01 =[Ϭ] p *F 01
F 01 =π(D 1 -2h) 2 /4
D 1 – diameter of the first tooth.
D 1 =d 0 min +2S z =38.65+0.1=38.75
P 01 =350*3.14(38.75-2*5) 2 /4=214637H
Q=(0.8….0.9)250000=200000
Since Q˂ Р х˂ we accept Р additional =200000H
Number of teeth in group Z c.
Z c ≥q 0 *π*D*Z slave* K p /P additional
K p = K p m K p to K p p =0.5*1.0*1.3=0.65
Maximum cutting force generated during broaching
P z = q 0 ∑ l p K p = q 0 *π*D*Z slave* K p / Z c =132*3.14*40*9*0.65=969888.3 H
P z ˂ P add; 969888.3˂200000 H
Full broaching allowance:
A=d max -d min =40.08-38.89=1.19 mm
Allowance for the transition part A lane = 0.2 mm
Allowance for cutting teeth A 0 = A-(A clean + A per) = 0.99mm
Number of rough teeth groups
n 0 = A 0 /2S z =0.99/(2*0.1)=4.95
Number of cutting teeth
Z p =(A 0 /2S z)+1=10.9
We accept Z p =11
Remaining part of the allowance
A ost = A 0 -(Z p -1)*2S z =0.91mm
Adjust the allowance for the transition teeth
Ap=2Sz+Aost=1.01mm
Taking into account the significant amount of allowance for transition teeth, we select the number of transition teeth -5, hence the distribution A p:
For the first transitional tooth - 0.14mm;
On the second -0.1mm;
On the third -0.05mm;
On the fourth – 0.02mm
On the fifth -0.01mm.
Tolerance for hole layout Tr=0.005 mm
Thus, the allowance for the transition teeth is Ap = 0.32mm
Number of broaching teeth Zк=7
Total number of broach teeth 18
Z=Zp+Zп+Zк=11+5+7=23
Pitch of calibrating teeth
For round broaches tk =(0.7…0.8)t=9.8…11.2mm
We accept t to =10
Tolerance for pitches of cutting and calibrating teeth.
Quality 14
Length of the working part of the broach
L slave =t(Z p +Z p)+t to *Z to =14(11+5)+10*7=156mm
Tooth diameter
Diameter of the first tooth D 1 =D 0 min =38.65mm
D 2 =D 1 +2 Sz =38.65+0.1=38.75mm
Diameter of calibrating teeth
D to =d max -0.005=40.8-0.005=40.795mm
Front guide dimensions
Transition cone length L pc =20
Distance from the front end of the broach to the first tooth
L 0 =L st +L zag +25mm=280+80+25=385mm
Rear guide dimensions: 35mm
Total feed length
L=l 0 +l slave +l zn =576mm.
We accept L=580mm.
Initial data:
Part profile for processing of which it is necessary to design a shaped cutter (Fig. 1);
Allowance for processing (indicated in the drawing);
Part profile tolerance ±0.05 mm;
- part material - steel35.
1.1. Calculation of average dimensions of a part profile
The average profile dimensions in the example under consideration coincide with the nominal dimensions of the part profile, since the profile tolerance is specified by b+u, i.e. located symmetrically. Therefore, it is not necessary to determine the average profile dimensions.
1.2. Selecting the Baseline Position
The given profile of the part has a relatively small height: h = 4 mm. The cutter edge profile mainly consists of sections located parallel to the axis of the part.
The section of the edge that makes it easiest to install the cutter at the level of the machine center line, i.e. in the axial plane of the part, are sections 1-2 and 5-6. Therefore, for a given part profile, we take the base line of the cutter to be located in edge sections 1-2 and 5-6 (Fig. 2).
1.3. Calculation of overall dimensions of the cutter
The width of the cutter is calculated L = L parts + 2n (Table 2.5, 2.6, 2.7):
L = 24 + 2 × 3 = 30 mm.
The height (depth) of the part profile q in the direction perpendicular to the cutter axis is calculated or determined graphically on an enlarged scale:
The diameter of the mounting hole d 0 is determined.
According to Table 2.3, feed S=0.02 mm/rev and cutting force
P z (L =1mm) =110H=11 daN * (Table 2.2).
Then the cutting force P z =P z (L =1mm) ×L=11 × 30=330 daN.
Taking into account the width of the cutter and the fact that the cutting force is small, we accept a cantilever mounting of the mandrel. According to Table 2.1, the diameter of the mounting hole is d0 = 27 mm.
The smallest permissible value of the outer diameter of the cutter is calculated
D>d0+2(q+l+m)
Taking l = 4mm and m = 8mm,
we get
D>27 + 2 (4 + 4 + 8)> 59.
Rounding to the nearest value according to the standard series of cutter diameters, we take D = 60 mm.
1.4. Correction calculation of cutter profile
The geometric parameters of the cutter are selected for sections of the cutting edge
1-2, 5-6, through which the base line passes (Fig. 4).
For the designed cutter, we take according to Table 2.4 the rake angle j = 18° (steel 35; Gb = 85 daN/mm^). clearance angle L = 12*.
The size of the blade is calculated, which determines the position of the cutter axis relative to the axis of the part (Fig. 5):
hust =R1 sinL;
hust = 30 *sin 12° = 30 X 0.20791 = 6.237.
We accept hcm =6.2.
The cutter profile in the front plane is calculated. To do this, a profile of the workpiece is drawn. Numbers I, 2, 3, 4, etc. characteristic points of the profile are marked.
The coordinates of the design points of the part profile are calculated based on the as-built dimensions of the part:
r1=r2=r5=r6=10 mm; l2=6 mm;
r3=11.4142 mm; l3=6.5858 mm;
r4= 12 mm; l4= 8 mm;
r7 = r8 = 14 mm; l5 = 10 mm;
For calculations, it is more convenient to write all equations in a calculation table. 1.1.
Table 1.1
Note to table 1.1.
Сз =A3-A1 = 10.96793 - 9.5106 == 1.47733; C3= 1.477;
C4 =A4-A1= 11.59536 - 9.5106 = 2.08476; C4 = 2.085;
C7.8=A7.8-A= 13.65476 - 9.5106 = 4.14416; C7.8 = 4.144.
The cutter profile in the axial plane is calculated (Fig. 6). The calculation is carried out according to the calculation table 1.2.
Table 1.2.
Continuation of Table 1.2,
Note.
Нз = R1 - Rз = 30 - 28.7305 = 1.2695;
H4 = R1 – R4 = 30 - 28.214 = I, 786;
H7.8= R1- R7 = 30 - 26.492 = 3.508.
1.5 Analysis of the values of the front and rear angles of the cutting part of the cutter
Calculation of the values of the front angles gx and rear angles ax at various points of the cutting edge of the cutter in a plane perpendicular to and axis of the cutter is carried out in the calculation table. 1.3.
Table 1.3.
Calculation of the values of the rear angles axn at the points of the cutting edge of the cutter in a plane perpendicular to the section of the edge under consideration is carried out according to calculation method.1.4.
Table 1.4
| N of design point | tg ax | g°x | sin gx | tgaxn = tgax singx | axn |
| 0,212557 | 0,212557 | 12° | |||
| 0,212557 | 0,212557 | 12° | |||
| 2¢ | 0,212557 | 0° | |||
| 0,282317 | 0,707107 | tgasn = 0.282317 * * 0.707107 = = 0.199628 | 11°17¢42² | ||
| 0,309456 | 0,309456 | 17°11¢42² | |||
| 0,309456 | 0,212557 | 12° | |||
| 5¢ | 0,212557 | 0° | |||
| 0,212557 | 0,212557 | 12° | |||
| 6¢ | 0,707007 | tga6¢n = 0.212557 * * 0.707107 = = 0.151301 | 8°36¢13² | ||
| 7¢ | 0,39862 | 0,707107 | tga7¢n = 0.39862 * * 0.707107 = = 0.281867 | 15°44¢29² | |
| 0,39862 | 0,39862 | 21°44¢09² | |||
| 0,39862 | 0,39862 | 21°44¢09² |
Calculation of the values of the limiting angles gxn at the points of the cutting edge of the cutter in a plane perpendicular to the section of the edge under consideration is carried out according to the calculation table 1.5.
Table 1.5.
| N of design point | gx | tg gx | sin jx | tg gXN = tg gxsin jx | gXN |
| 18° | 0,32490 | 0,32490 | 18° | ||
| 18° | 0,32490 | 0,32490 | 18° | ||
| 2¢ | 18° | 0,32490 | 0° | 0° | |
| 15°42¢28² | 0,281234 | 0,707107 | tgg3N = 0.281234 * * 0.717101 = = 0.198862 | 11°14¢50² | |
| 14°55¢22² | 0,266505 | 0,266505 | 14°55¢22² | ||
| 18° | 0,324920 | 0,324920 | 18° | ||
| 5¢ | 18° | 0,324920 | 0° | ||
| 18° | 0,324920 | 0,324920 | 18° | ||
| 6¢ | 18° | 0,324920 | 0,707107 | tg gGN = 0.32492 * * 0.707107 = = 0.229753 | 12°56¢22² |
| 7¢ | 12°45¢01² | 0,226282 | 0,707107 | tg giN = 0.226282 * 0.707107 = = 0.160006 | 9°05¢38² |
| 12°45¢07² | 0,226282 | 0,226282 | 12°45¢01² | ||
| 12°45¢01² | 0,226282 | 0, 226282 | 12°45¢01² |
For clarity, graphs of the values of the rear and front angles of each section of the cutting edge are plotted. The abscissa axis shows the axial dimensions, and the ordinate axis shows the angle values.
On the graphs rie. 7 and 8 angle values do not have negative values. Their minimum values correspond to the conditions for satisfactory operation of the cutting edges, except for points 2¢ to 5¢.
The cutting part of the cutter has points 2 and 5, which are the intersection points of edge sections 1-2 and 5-6 with radius edge 2-5. These points need to be considered specially. If we consider them to belong to straight sections 1-2 and 5-6, then they will have front and back angles accepted? for these sections for which the radial plane coincides with the plane normal to the edge.
For a curved section of radius t, these planes do not coincide. The plane tangent to the circle at points 2 and 5 is located normal to the cutter axis. As a result, the front and rear angles in the plane perpendicular to the curve at these points are equal to zero. Existing recommendations on the possibility of introducing undercuts, undercuts, turning the cutter, inserting sections of the in-mitt back surface in the area of such points cannot be used, because the profile is symmetrical, the radius is small and there are only points that operate at zero angles. As a result, the greatest wear on the cutter will be located at these points. In such cases, it is necessary to decide on the advisability of using a shaped cutter or, if its use is necessary, to establish the appropriate conditions for its operation.
The strength of the cutting part in the zones of the maximum value of one of the angles does not decrease, because is compensated by a corresponding decrease in the value of the other angle.
Thus, the choice of the position of the base line, the diameter of the cutter and its geometry satisfies the basic requirements for cutters and can be finally accepted.
If one of the angles is insufficient, it is necessary to change the initial value of the corresponding angle and carry out a correction calculation of the dimensions of the cutter profile, the angles of the cutting part and their analysis.
1.6. Designation of cutter design dimensions.
The dimensions of the corrugations and the design size l2 of the cutter are assigned according to Table 2.9 and Fig. 15.
The length of the recess for the screw head l1 is determined depending on the width of the cutter.
l1=(1/4 … 1/2)L
The diameter of the recess for the screw head d1 is assigned depending on the diameter of the cutter mounting hole d0.
For a hole with a length of l>15.mm, the length of the polished belts is taken
For the designed cutter we accept:
L = 30 + 5 = 35 mm;
The size of the outer diameter of the cutter D is made according to h / 2.
The diameter of the mounting hole d0 is made according to H7. The remaining design dimensions of the cutter are made to 14-16th to valets.
Cutter design indicating elements, dimensions, tolerances and requirements
technical specifications are shown in Fig. 16.
2. REFERENCE MATERIAL FOR DESIGNING SHAPED CUTTERS
| Table 2.1. Minimum diameters of mandrels d0 for fastening round cutters, mm. | |||||||||||||||||||||||
| Cutting force Pz daN | Cutter width L, mm. | ||||||||||||||||||||||
| From 10 to 13 | Sat 13 to 18 | Sat 18 to 25 | St 25 to 34 | St 34 to 45 | St 45 to 60 | St 60 to 80 | |||||||||||||||||
| Cantilever mandrel mounts | |||||||||||||||||||||||
| Up to 100 Sv100 up to 130 Sv130 up to 170 Sv170 up to 220 Sv220 up to 290 Sv290 up to 380 Sv380 up to 500 Sv500 up to 650 Sv650 up to 850 Sv 850 up to 1100 | - - - - - - - - - - | - - - - - - - - - - | |||||||||||||||||||||
| Double-sided mandrel mounting. | |||||||||||||||||||||||
| Up to 100 Sv100 up to 130 Sv130 up to 170 Sv170 up to 220 Sv220 up to 290 Sv290 up to 380 Sv380 up to 500 Sv500 up to 650 Sv650 up to 850 Sv 850 up | - - - - - - - - - - | - - - - - - - - - - | - - - - - - - - - - | ||||||||||||||||||||
Note. The numbers in column 1 refer to cutters with D< 3L , в граф 2 – к
cutters D > 3L.
Table 2.2
Cutting modes (shaped turning)
Notes: 1. Cutting speeds V remain constant regardless of cutting width.
2. Tabular values of cutting force Pr. and elective power Ne are multiplied by the cutter width L.
| Cutter width L, mm | Processing diameter, mm | |||||||
| 60-100 | ||||||||
| Feed S mm/rev | ||||||||
| 0,02-0,04 | 0,02-0,06 | 0,03-0,08 | 0,04-0,09 | 0,04-0,09 | 0.04-0,09 | 0,04-0,09 | 0,04-0,09 | |
| 0.015-0,035 | 0,02-,052 | 0,03-0,07 | 0,04-0,088 | 0,04-,0088 | 0,04-0,088 | 0,04-.088 | 0,04-0,088 | |
| 0.01-0,027 | 0,02-0,04 | 0,02-0,055 | 0,035-0,077 | 0,04-0,082 | 0,04-0,082 | 0,04-0,082 | 0,04-0,082 | |
| 0,01-0,024 | 0,015-0,035 | 0,02-,.048 | 0,03-0,059 | 0,035-0,072 | 0,04-0,08 | 0,04-0,08 | 0,04-0,08 | |
| 0,008-0,018 | 0,015-0,032 | 0,02-0,042 | 0.025-0,052 | 3.03-0,063 | 0,04-0,08 | 0,04-0,08 | 0.04-0,08 | |
| 0,008-0,018 | 0,01-0,027 | 0,02-0,037 | 0,025-0,046 | 3,02-0,055 | 0,035-0,07 | 0,035-0,07 | 0,035-0,07 | |
| - | 0,01-0,025 | 0,015-0,034 | 0,02-0,043 | 0,025-0,05 | 0,03-0,065 | 0,03-0,065 | 0,03-0,065 | |
| - | 0,01-0,023 | 0,01-5-0,031 | 0,02-0,039 | 0,03-0,046 | 0,03-0,06 | 0,03-0,06 | 0,03-0,06 | |
| - | - | 0,01-0,027 | 0,015-0,034 | 0,02-0,04 | 0,025-0,055 | 0,025-0,055 | 0,025-0,055 | |
| - | - | 0.01-0.025 | 0,015-0.031 | 0,02-0,037 | 0.025-0,05 | 0.025-0,05 | 0,025-0,05 | |
| - | - | - | - | 0.015-0,031 | 0,02-0,042 | 0,025-0,046 | 0,025-0,05 | |
| - | - | - | - | 0,01-0.028 | 0,015-0,038 | 0,02-0.048 | 0,025-0,05 | |
| - | - | - | - | 0,01-0,025 | 0,015- 0,034 | 0,02- 0,042 | 0,025- 0,05 |
Note. Lower feed rates - for complex profiles and hard materials; large - for simple profiles and soft metals.
Explanations for Fig. 9-14.
I. If there are extreme sections of the profile parallel to the axis of the cutter (Fig. 9, 10, 11, 13, 14) or if there are concave profiles of the product, the amount of overlap h per side is taken depending on the width L of the product according to Table 2.5.
Table 2.5.
Moreover, if the height of the protrusion is not limited by the dimensions of the height of the product profile, the protrusion should overlap the product profile at a height of 1 - 3 mm (Fig. 11, 12)
4. For cutters for products with dimensions l1 exact in profile width (Fig. 13, 14), mounting projections of height B are made depending on the width of the projection m1 (Table 2.7)
Table 2.7.
Table 2.9
Size of corrugations (Fig. 15)
1. Calculation and design of shaped cutter
.1 General information
A cutter is called a shaped cutter, the cutting edges of which have a shape determined by the shape of the part’s profile. They provide high productivity, uniformity of profile shape and dimensional accuracy of processed parts and are used in large-scale and mass production.
Shaped cutters can be divided into the following groups:
in shape: round, prismatic, rod;
according to their installation relative to the part, prismatic cutters are divided into cutters with a radial edge and tangential ones;
according to the location of the axis: with a parallel arrangement of the axis in relation to the axis of the part and an inclined arrangement of the axis or mounting base;
according to the shape of the generatrix: round cutters with annular generatrices, round with helical generatrices, prismatic with flat generatrices.
In modern mechanical engineering, radial prismatic and round shaped cutters are mainly used for turning shaped surfaces; Tangential and rolling shaped cutters are less common.
Prismatic cutters are used for processing external surfaces, have increased rigidity and reliability of fastening, increased processing accuracy, better heat removal, and are easier to install on machines compared to round ones.
Round (disc) cutters are used for processing external and internal surfaces; they are more technologically advanced in manufacturing, but more difficult to install, have a greater number of regrinds and an increased service life compared to prismatic ones.
To secure round shaped cutters into a holder, the end surfaces of these cutters are provided with corrugations, holes for a pin, or grooves at the end.
Radial shaped cutters have a feed directed along the radius, and tangential cutters have a feed directed tangentially to the inner surface of the part. In production, shaped cutters with radial feed are most widely used, as they are easier to operate and set up.
Compared to conventional cutters, shaped cutters provide:
) identity of shape, dimensional accuracy of parts, since they do not depend on the qualifications of the worker, but mainly on the accuracy of the manufacture of the cutter;
) high productivity due to large savings in machine time associated with a reduction in the cutting path, and auxiliary time required for installation and adjustment of the cutter when changing it;
) high durability due to the large number of allowed regrinds;
) less defects;
Workpiece material - steel 20,
σ in = 400 MPa (≈40 kgf/mm 2).
1.2 Graphical method for determining the cutter profile
We build the profile of the workpiece, for which we draw an axis, from which we set aside the corresponding dimensions of the workpiece profile, and build a complete profile in the lower left corner of the drawing.
We project the obtained points 1, 2, 3, 4, 5, 6 of the workpiece profile onto the horizontal axis passing through the center of the workpiece O (points 1 / -2 / , 3 / - 4 / , 5 / - 6 /), through which we draw the corresponding circles equal to r 1-2, r 3-4, r 5-6.
4. From point 1" (A"), draw a line (trace) of the front surface of the cutter blade at an angle y and a line (trace) of the rear surface at an angle a.
We designate the intersection points of the corresponding circles of the incisors as r 1-2, r 3-4, r 5-6. with the line of the front surface of the cutter through A 1-2, A 3-4, A 5-6.
6. From these points we draw lines parallel to the rear surface of the cutter.
7. We construct the profile of the cutter in a normal section, that is, in a section perpendicular to its rear surface (section A A): draw the line MM; we set aside from this line the axial dimensions l 1, l 2, l 3, l 4 and l 5, which correspond to the axial dimensions of the workpiece being processed; We lay down on horizontal lines parallel to the line MM, segments equal to the distances between the lines parallel to the rear surface of the cutter, find points /", 2", 3", 4", 5", 6" and, connecting them with straight lines, we obtain a profile cutter in normal section.
8. The construction of a template and a counter-template for controlling the shaped profile of the cutter is reduced to the transfer of all segments 1"-2", 1"-3", 1"-4" and 1"-5" relative to the nodal contour point 1".
We select the overall and design dimensions of the cutter according to the table. 44 depending on the greatest profile depth t max of the part being manufactured.
We make a working drawing of a shaped prismatic cutter according to the instructions (see Chapter 1, §3).
If the front angle of the blade is γ = 0, then the profile of the shaped prismatic cutter is constructed in the same order, only the line of the front surface will be horizontal, i.e. points 1"-2", 3"-4", 5"-6" will coincide with points A 1-2, A 3-4 and A 5-6.
1.3 Analytical calculation of cutter profile
The front and rear angles are determined according to Table 47: γ=25 0, α=12 0.
The dimensions of additional cutting edges for cutting and trimming are taken as follows: b 1 = 1 mm, b = 7 mm, c = 0 mm, φ 1 = 15 0, φ face = 45 0.
Total width of the cutter along the workpiece axis:
L p =l g +f+c+b+b 1 =50+0+0.5+7+1=58 mm.
4. The greatest depth of the part profile t max = 7.5 mm.
The overall and structural dimensions of the cutter with end corrugation for the greatest profile depth t max = 7.5 mm are selected from the table D = 108 mm, d (H8) = 102 mm, d 1 = 99.9 mm, b max = 16 mm, k = 0.5 mm, r=0.5mm, d 2 =6mm, D 1 =45mm, h p =R 1 sinα=45sin12=6.3mm. - installation height of the cutter.
Cutter sharpening height H=Rsin(α+γ)=45sin(25+12)=15.4mm,
where R is the radius of the cutter;
According to the dimensions in the workpiece drawing, the radii of the circles of the workpiece profile nodal points r 1, r 2, r 3, r 4, r 5, r 6 and the axial distances to these points from the end to the workpiece l 1-2, l 1-3, l 1 -5, etc. the following:
r= r 2 =17.5 mm
r 3 = r 4 =25 mm l 1-2.3 =15 mm l 1-5 =40 mm
r 5 = r 6 = 21mm. l 1-4 =30 mm l 1-6 =50mm
Tolerances for the specified dimensions are taken equal to 1/3 of the tolerances for the corresponding dimensions of the workpiece being processed.
We correct the cutter profile: we summarize the correction calculation data in the table:
|
Calculation formula |
Parameter value (mm, … 0 …) |
|
γ 1 =25 0 r 1 = r 2 =17.5 sin γ 1 =0.382 h and =6.685 |
|
|
A 1 =r 1 cosγ 1 sin γ 3 =h and /r 3 |
cos γ 1 =0.924 A 1 =16.17 r 3 =25mm sin γ 3 =0.267 γ 3 =15.31 |
|
A 3 =r 3 cosγ 3 C 3 = A 3 - A 1 sin γ 4 = h and / r 4 |
cos γ 2 =0.99, r 3 =10 mm A 3 =r 3 cosγ 3 =24.309 r 4 =25 r 5 =21 C 3 = A 3 - A 1 =8.139 sin γ 4 =0.082 γ 4 =0.977 |
|
A 4 = r 4 cosγ 4 C 4 = A 4 -A 1 |
cos γ 4 =0.99 r 5 = r 6 =21 mm. A 4 = 24.999 C 4 = 25-16.17 = 8.827 sin γ 6 γ 6 = 20.62 |
|
A 6 = r 6 cosγ 6 |
cosγ 6 A 6 =0.9479*21= 20 |
|
C 5 = C 6 = A 6 -A 1 |
C 5 = C 6 =8.47 |
|
ε 1 =α 1 + γ 1 |
ε 1 = 25+12 = 37 |
|
ε 1 =α 1 + γ 1 |
α 1 =12 0 γ 1 =25 0 ε 1 =37 0 cosε1 |
|
C 3 = 8.139 P3 = 6.803 |
|
|
P 4 = С4cosε 1 |
C 4 = 8.827 P 4 = 7.377 |
|
P 5 = P 6 = C5cosε 1 |
C 5 = 3.83 P 5 = P 6 = 2.93 |
The construction of templates and counter-templates for monitoring the shaped profile of cutters (while monitoring deviations in the dimensions of grinding shaped surfaces on cutters) is reduced for round cutters to determining the difference in the radii of all nodal points of the calculated shaped profile relative to the nodal contour (starting) point 1:
P 3 = P 4 = R 1 - R 3 = 3.58 mm
P 5 = P 6 = R 1 - R 5 = 4.06 mm
Tolerances on the linear dimensions of the shaped profile of the template during its manufacture should not exceed ±0.01 mm.
1.4 Calculation of cutting conditions during turning
Depth of cut t = tmax = 7.5 mm,
where tmax is the greatest depth of the part profile.
Cutting speed
where T is the average tool life,
Сυ, m, y - coefficient and exponents in,
A coefficient that is the product of coefficients taking into account the influence of the workpiece material Kmυ, surface condition Kпυ, tool material Kиυ.
We accept: =120 min; Сυ=22.7; m=0.3; y = 0.5;
,
where kg is a coefficient characterizing the steel group according to machinability, kg = 1.0; υ is an exponent, nυ = 1.75;
Kпυ = 0.8; Kiυ = 1;
1,74 ∙ 0,8 ∙ 1 = 1,39.
m/min.
Spindle speed corresponding to the found speed
min-1.
We adjust the spindle rotation speed according to the passport data of the 1B290-4K machine and set the actual value of the rotation speed:
nd = 160 min-1.
Determine the actual speed of the main cutting movement
m/min.
Cutting force
Cutter length = 65 mm.
For given processing conditions, coefficients and exponents
212;=
1;= 0,75;= 0 .
We take into account correction factors for cutting force
Kpz=KМр · Kγp · Кφр · Кλр · Крр
;= 0,75
;γp=1.0 ,
Kφр=1.0,
Кλр=1.0,
Kr=1.0 .=1.1 1.0 1.0 1.0 1.0=1.1=10 212 651 0.04 0.75 33.410 1.1= 12490N.
kW.
We check whether the drive power of the machine is sufficient. Nshp=6.3 kW
Nres ≤ Nshp; 6.2< 6,3, т.е. обработка возможна
8. Main time
Working stroke length (mm) of the cutter:
L = l + lвр + lп,
Infeed size:
lвр = t · ctg φ = 7.5 ∙ ctg 45° = 7.5 mm;
Overtravel of the cutter: p = 1-3 mm, take lp = 2 mm;
Length of treated surface:
l = 70 mm, = 70+ 7.5+ 2 = 79.5 mm,
min
2. Calculation and design of a hob cutter
2.1 General provisions
Milling is one of the highly productive and widespread methods of metal cutting. This is done using a tool called a milling cutter. A milling cutter is a multi-toothed tool, which is a body of rotation, on the generatrix of which there are cutting teeth or at the end.
The main movement during milling is rotational (the milling cutter has it); The feed movement (usually linear) can be carried out by both the workpiece and the cutter itself.
External planes, grooves and shaped surfaces are processed by milling, and in the latter case it is necessary to have a cutter of the appropriate shape. There are also cutters for processing bodies of rotation, for reaming metals (saws), for making threads (thread cutters), for making gears (gear cutters).
The cutters are made one-piece, composite, prefabricated with a cutting part made of high-speed steels or with hard alloy plates.
Due to the great advantages of cutters equipped with hard alloy inserts (high productivity; high quality of the machined surface, sometimes eliminating the use of grinding; the ability to process hardened steels; reduced processing costs, etc.), they are successfully used in the metalworking industry and have replaced many cutters from tool tools. steels
Along with the particularly widespread end mills with carbide inserts, carbide disk, end, key and shaped milling cutters are used in industry. .
A hob gear cutter can be presented in the form of a set of combs fixed on a cylindrical surface or in the form of a worm, the turns of which are converted into cutting teeth by cutting transverse grooves so that rake angles γ are formed on them, and by backing the teeth to obtain rear angles α.
The basis of the profile of standard hobs is a convolute worm, the turns of which in a section normal to the direction of the turn have the rectilinear profile of the original gear rack. The profile of the original rack is characterized by the profile angle α p =20 0, tooth pitch P p =πm, the estimated height of the tooth h p and its head h /, as well as the normal thickness of the cutter tooth S n =P n -s n, where s n is the tooth thickness the wheel being cut along the normal line.
According to their purpose, hobs are distinguished for cutting cylindrical spur and helical gears, for processing worm wheels, for processing worm wheels, splined shafts, sprockets, etc. By design, hobs are either solid or prefabricated; they can be mounted on mandrels (nozzles) or using shanks.
2.2 Calculation of a hob cutter for processing spline rollers
Milling cutter:
z×d×D =10×102×108.
Roller:
b=16 mm,=115 mm,=0.5 mm,=0.5 mm,
Material: st50V =300-330,
heat treatment - normalization,
type of processing - finishing.
Determination of the calculated roller diameters.
Design outer diameter:
Dp=Dmax-2fmin=108.012-2·0.5=107.012 mm.
Design inner diameter:
dp=dmin+0.25E1=99.9+0.25·0=99.9 mm,
where E1 is the tolerance value for the internal diameter.
Estimated slot width:
bp=bmin+0.25E=15.965+0.25·0.150=15.973 mm,
where E is the tolerance value for the slot width.
Roller initial circle diameter:
The slot angle γn is determined with an accuracy of 1".
Determination of tooth profile dimensions.
Determine the pitch of the cutter turns along the normal:
tп== 
mm,
where z is the number of roller splines.
Cutter tooth thickness along the initial straight line:
Sn=tn-SbH=DHmm.
Height of the ground part of the cutter profile:
,
where hH is the profile height from the initial straight line:
hH=RH(sinαK-sinγH) sinαK,
RH= 
mm.γH= 
.
γH=10º.αK= 
αK=20º.=29.5(sin20º-sin10º) sin20º=1.4 mm.
hз= 
mm
mm.
Ledge dimensions at 35º:
length f2=2f=2·0.5=1 mm,
height h2=f2·tg35º=0.7.
Flute dimensions for easy grinding:
width l=tn-(Sn+2f2)=33.3-(17.402+2·1)=13 mm
depth h4=1.5-3.0 mm, take h4=2 mm,
radius r=1-2 mm, take r=2 mm.
Total height of the tooth profile: h0=h+h2+h4=2.899+0.7+2=5.599 mm.
Definition of cutting part elements.
The values De, D1, d1, b, t1, z1, rK, c1 are selected depending on the pitch tп for medium series spline hob cutters:
a1 = 0.6 mm, = 125 mm, = 60 mm, = 40 mm, = 10 mm, = 43.5 mm, = 2 mm, = 5 mm.
We select the rake angle depending on the working conditions: for finishing cutters - γ=0.
The clearance angle at the top of the teeth is αк=9-12º, we take αк=10º.
Amount of first backing:
K= 
=5,18,
Number of cutter teeth.
Amount of additional backing:
K1=(1.2-1.5)K=5.52-6.9, take K1=6.
The size of the polished part of the back of the head is determined by the angle:
Ψ=(0.4-0.5)η, where
Ψ=12-15, we accept Ψ=12º.
Diameter D´ is determined:
D´=De+2(K1-K) 
=130 mm.
Groove depth:
H=h0+K1-(K1-K)+rK=5.599+6-(6-5.18)+2=13.671 mm.
Cutter length:
L=2,=5,=2=103.3 mm.
10. Hole length:
l=(0.2-0.3)L=26.64-39.96.
we take l= 30.99 mm.
The position of the design section is determined by the angle:
Average design diameter:
Dt.calc=De-2hз-2hn-mm.
Helix angle:
sinωcalc= 
ωcalc = 5º.
Helix pitch:
Hcn=π Dt.calc ctgωcalc=3.14·119·ctg5º =3316 mm.
Axial pitch of turns:
t0= 
mm.
We accept P6M5 as the material for making the cutter.
Graphic method for constructing a cutter profile.
We draw, on the selected scale, the initial circle of the spline roller, the initial straight line of the cutter and the auxiliary circle. Through the engagement pole we draw a line of the side profile of the spline (AP) tangent to the auxiliary circle (Fig. 2).
We build a line of engagement:
a) on the line AR we draw points 1, 2, 3,4 at approximately equal distances
b) through these points we draw normals to the AR until they intersect with the initial circle at points 1´, 2´, 3´, 4´.
c) we draw trajectories (circles) of movement of points 1, 2, 3, 4 when the roller rotates and on them we make notches from the pole P with a length equal to the lengths of the normals 11´, 22´, 33´, 44´, we obtain points of the engagement line 1´ ´, 2´´, 3´´, 4´´.
We build a profile curve:
a) through points 1´´, 2´´, 3´´, 4´´ we draw the trajectories of movement of the cutter profile points and on them we lay off segments equal to the arcs Р1´, Р2´, Р3´, Р4´, we obtain the corresponding points of the cutter profile I, II, III, IV.
b) on the profile curve we mark the actual (active) section of the profile equal to h.
Replacing a profile curve with a circular arc.
To simplify the manufacture of cutters, templates and counter-templates, a theoretical curve, plotted graphically or calculated analytically using the X and Y coordinates, is usually replaced by a single arc of a circle. We define a circle using three points. Two points usually take the extreme points of the profile O and M. The position of the third point is determined by the selection method from the condition of minimum error
the resulting profile compared to the theoretical one. Usually the optimal solution is obtained for a point lying in the middle of the profile. Substituting the coordinates of three points into the equation of a circle
(x-p)2+(y-q)2=R2
and by solving them together we determine the coordinates of the center O1 and the radius R0.
.3 Calculation of cutting conditions during milling
Milling is carried out on a VS-50 slot milling machine.
Determining the cutting depth
t = = 3.006 mm.
We assign the feed per revolution of the gear being cut
So table = 0.8 mm/rev.
S=S∙KMS∙KFS
KMS=0.9,=1.0,=0.8∙0.9 ∙1.0=0.72 mm/rev.
3. Durability period and wear of the cutter:
Ttable = 300 min, z = 0.3 mm - blunting criterion,
Determine the speed of the main cutting movement
v=vtable∙Kmv∙Kфv∙Kzv∙Kuv∙KΔv∙Kv∙KTv, wheretable=25m/min,
coefficients are taken as =0.9, fv=1.0,=1.1,=1.0,Δv=1.0,=1.0=1.25,
0.6.=25∙0.9 ∙1.0∙1.1∙1.0∙1.0∙1.25=30.93 m/min.
Spindle rotation frequency corresponding to the found speed of the main cutting movement:
where dao=90mm.
min-1
We adjust the rotation speed according to the machine data and set the actual rotation speed:
nd = 100 min-1.
We determine the actual speed of the main cutting movement:
m/min;
Power spent on cutting:
N=10-5∙CN ∙SYn∙dUn∙v∙Kn,
where we take the coefficients according to:
CN=42,=0.65,=1.1,=1.1.=10-5∙42∙0.72 0.65∙421.1∙30b93∙1.4=0.69 kW.
We check whether the drive power of the machine is sufficient:
unit VS-50 Nshp = Nd ∙ η = 6 ∙ 0.85 = 5.1 kW
69 < 5,1
кВт, т.е. обработка возможна.
3. Calculation and design of a twist drill
3.1 General provisions
To process holes, various blade tools are used, depending on the service purpose of the part and the technological process of its manufacture. The most common tools are drills, countersinks, countersinks, and reamers. The choice of the type of axial tool depends on the hole parameters: diameter, depth, accuracy and requirements for the location of the geometric axis, as well as on the physical and mechanical properties of the material being processed, and the productivity of the processing process.
Drills are cutting tools designed to create holes in solid material. During the drilling process, two movements are carried out: rotational - around the axis of the tool and translational - along the axis of the tool. Drill bits are also used to drill out pre-drilled holes. Various types of drills are common in industry.
Twist drills are most widely used in industry. They are used for drilling holes with a diameter of 0.25 to 80 mm in various materials at a speed of 40-50 m/min.
The main dimensions and angles of the drill blades are standardized. The geometric elements of the working part of drills (w, g and 2j) depend on the material of the workpiece and drill. The angle of inclination of the transverse cutting edge for drills with a diameter of up to 12 mm is taken to be 50 °, for drills with a diameter over 12 mm - 55 °. The clearance angle a is different at different points of the cutting edge. For standard twist drills, at the point furthest from the drill axis (blade tip) a=8...15°, at the point closest to the axis a=2°...26°.
Technical requirements for the manufacture of twist drills are given in GOST 2034-80. The shanks of drills with a conical shank have a Morse taper, carried out by GOST 25557-82.
3.2 Calculation and design of a high-speed steel twist drill with a conical shank
We determine the diameter of the drill d = 22 mm GOST 885-77
We determine the cutting mode:
a) find the feed according to (Table 25, p. 277)
S=0.47...0.54 mm/rev, take S 0 =0.5 mm/rev
b) Determine the speed of the main cutting movement: select the coefficients according to (Table 28, p. 278);
;
C υ =17.1, q=0.25, x υ =0, y υ =0.4, m =0.125;
Drill life T=60 min. (Table 28, page 276);
Correction coefficient K υ =K M υ ´K U υ ´K l υ =0.73´1.0´1.0=0.73, where
K M υ = 0.73 - coefficient. on the quality of the processed material (.261-263);
K U υ = 1.0 - coefficient. on instrumental material (Table 6);
K l υ = 1.0 - coefficient. taking into account the depth of the drilled hole (Table 31)
m/min;
Spindle speed
min -1
6. Actual speed of the main cutting movement
m/min
Axial component of cutting force.
n=0.6 (Table 9, p. 264); p =42, 7, q p =1, 0, y p =0, 8 ([ 3], table 32, p. 281);
P x = 9.81´42.7´22 1.0´0.5 0.8´1.16= 396 N
Moment of cutting resistance forces (torque);
M =0.021, q =2.0, y=0.8 (Table 32, 281 p.); n p = 0.6 (Table 9, p. 264);
av = 9.81´0.021´22 2.0´0.5 0.8´ 1.16= 68.8 Nm.
Determine the number of the Morse taper of the shank.
Determine the average diameter of the shank
;
μ = 0.16 - coefficient. friction of steel on cast iron;
θ= 1 ° 30 " - half the angle of the cone;
∆θ=5 "cone angle deviation;
According to GOST 25557-82, we select the nearest larger Morse cone No. 2 with a foot with the following main design dimensions:
D=17.78, D 1 =18, d 2 =14, d 3max =13.5, l 3max =75, l 4 =80, bh13=5.2, a=5,=6, c=10, R 1 =1.6
We determine the length of the drill according to GOST 10903-77
L=240 mm - total drill length
l 1 =140 mm - length of the working part
The center hole is made according to the form B GOST 14034-74.
We determine the geometric and design parameters of the working part of the drill (tables 43-45, 151 pp.).
helical groove inclination angle w = 35 °;
angles between cutting edges 2j=127 °, 2j 0 =70 °;
Angle of inclination of the transverse groove Y = 55 °;
Dimensions of the sharpened part of the lintel:
A=3.08, l=6 mm
Helical groove pitch:
mm.
The thickness d c of the drill core is chosen depending on the diameter of the drill: we take the thickness of the core at the front end of the drill equal to 0.14 D. Then d c = 0.14´22 = 3.35 mm. The thickening of the core towards the shank is 1.4-1.8 mm per 100 mm of length. We take this thickening to be 1.5 mm.
The reverse taper of the drill (reducing the diameter towards the shank) per 100 mm of the length of the working part is 0.04-0.10 mm. We accept a reverse taper of 0.1 mm.
The width of the ribbon (auxiliary rear surface of the blade) f 0 and the height of the back of the head k are selected according to (Table 63): in accordance with the diameter of the drill f 0 = 2.4 mm, k = 1.2 mm.
Pen width B=0.58 D=0.58´22=12.76mm.
The geometric elements of the cutter profile for milling a drill groove are determined by a graphical or analytical method. Let's use a simplified analytical method.
Large profile radius
R 0 = C R ´C r ´С φ ´D, where
with a core to diameter ratio d c /D =0.14, C r =1;
where D φ - cutter diameter; at D φ =13ÖD C φ =1, therefore
R 0 = 0.6 16 1 1 = 8.77 mm.
Smaller profile radius
R k =C k ´D = 0.17´22=3.993 mm., where C k =0.015w 0.75 =0.17;
Profile width
B= R 0 + R k =9.92+3.74=12.77 mm.
Based on the values found, we construct the profile of the groove cutter. We establish the basic technical requirements and tolerances for the dimensions of the drill (GOST 885-77).
Maximum deviations of drill diameter D=22h9, (-0.043) mm. The tolerance for the total length and the length of the working part of the drill is equal to (± IT14/2) according to GOST 25347-82. The radial runout of the working part of the drill relative to the axis of the shank should not exceed 0.15 mm. Maximum deviations of the shank cone dimensions are established according to GOST 2848-75 (accuracy level AT8). Angles 2j= 127° ± 2°, 2j 0 =70° +5°. Helical groove angle w =35° -2°. Maximum deviations in the dimensions of the point of the cutting part of the drill are +0.5 mm.
The hardness of the working part of the drill is 63-66 HRC e, at the shank foot 32-46.5 HRC e.
We make a working drawing indicating the technical requirements for the drill
3.3 Cutting mode when drilling
Processing is carried out on a vertical drilling machine 2N125
Depth of cut
t= D/2 = 22/2=11 mm
We select the feed S o =0.47..0.54, take S o =0.5 mm. We check the accepted feed according to the axial component of the cutting force, allowed by the strength of the machine feed mechanism. To do this, we determine the axial component of the cutting force P x = 396N;
It is necessary to fulfill the condition P 0 £P max ,
P max - the maximum value of the axial component of the cutting force allowed by the machine feed mechanism. According to the passport data of the 2N125 machine: P max = 9000N. Since 396< 9000, то назначенная подача вполне допустима.
Allowable wear of the drill ([5], table 1 9, 228 c/] h з =0.5mm
4. The speed of the main cutting movement allowed by the cutting properties of the drill υ and = 22.14 m/min
Spindle speed
min -1
We adjust the spindle speed for the machine n d = 320 min -1
6. Actual speed of the main cutting movement
m/min
Torque from cutting resistance forces during drilling
Mcr = 68.8 Nm
Power spent on cutting
kW
Let's check whether the machine's power is sufficient. Processing is possible if
N cut £N pcs, N pcs =N d ´h= 2, 26´0, 8=2.8 kW
Main time
, min
where L= y+∆+l =0, 4´16+2+30=38.4mm is the full path traversed by the drill in the feed direction; y=0.4D; ∆=1..3;
3. Calculation and design of circular broach
.1 General information
hob cutter
Broaching is one of the most effective methods of mechanical processing, allowing to obtain high-precision products (up to 6th grade) and a machined surface roughness of up to 0.32 microns. When using carbide smoothers 0.08. Broaching is mainly used in large-scale and mass production, but this method is also successfully used in small-scale and even single-piece production, when broaching is the only possible or most economical processing method.
Various types of broaches are used as a cutting tool when broaching. A broach is a multi-blade tool with a number of blades successively protruding one above the other in a direction perpendicular to the direction of the speed of the main movement, designed for processing with a translational or rotational main cutting movement and no feed movement. Broaches have significant advantages over other types of tools. They are the most highly productive tools, approximately a hundred times or more productive than countersinks and reamers. When broaching, the operations of roughing, semi-finishing and finishing are combined. This increases productivity, reduces the range of cutting and measuring tools used, and reduces the number of machines and technological equipment.
Broaches are a metal-intensive, difficult to manufacture and therefore expensive tool. The economic feasibility of their use is justified by ensuring optimal structural elements and cutting conditions, high-quality production of broaches and proper operation.
Broaching is used to process internal (closed) and external (open) surfaces. Accordingly, a distinction is made between internal and external broaches. A type of broaches are broaches, the design of which is not fundamentally different from the design of broaches, however, during the cutting process, the broaches are subjected mainly to compressive forces, while the broaches work in tension. The areas of application of broaching are very diverse. Internal broaching is used to process holes of various shapes, including round, square, polyhedral, slotted with slots of various profiles, as well as keyway and other grooves. External broaches are mainly used to process flat and shaped surfaces, grooves, ledges, corrugations, etc.
Broaching of surfaces of revolution can be done with prismatic or spiral broaches. During the processing process, the part rotates quickly and the broach moves relatively slowly. A spiral broach is a disk on which a prismatic broach is screwed, as it were. The cutting edges of the teeth of such a broach are located at different distances from the axis. The difference in the radii of adjacent teeth determines the feed per tooth.
3.2 Initial data:
Calculate and design a round broach for a cylindrical hole with diameters D in a workpiece made of U10A steel with hardness 202-239 HB, and length l and v. The hole is drawn after drilling to diameter Do on a horizontal broaching machine 7534. The roughness parameter of the drawn surface is Ra=2 µm. We calculate the broach according to the scheme given in GOST 20365-74*.
D=45H7(+0.025) mm.
o=43.7mm. We will accept the broach material P18, welded structure, shank made of 40X steel.
Part sketch:
For round holes, the allowance for broaching on the diameter can be calculated using the equation when preparing a hole by countersinking:
Ао=2А=0.005Dо+(0.05-1)√l+(0.7-1)δ=0.005*43.7+0.1*11=1.3mm.
Lift per tooth on side Sz, select by: =0.025-0.03mm, take Sz = 0.03m.
For our example, we take Zз=3 and distribute the lift per tooth as ½ Sz=0.015mm; 1/3 Sz=0.01mm; 1/6 Sz=0.004mm.
The profile, dimensions of the tooth and chip grooves between the teeth are selected depending on the area of the metal layer removed by one cutting tooth of the broach. It is necessary that the cross-sectional area of the chip flute between the teeth meets the condition:
where k = 2-5 is the fill factor of the groove, we take k = 3, . is the cross-sectional area of the metal cut removed by one tooth,
Fc=ld Sz=90·0.03=2.7 mm2
Groove cross-sectional area, mm2;
We find
Fk = Fc ·k =3·2.7=3.75 mm3.
Using Fk = 12.5 mm2 for the nearest larger value, with a curvilinear shape of the chip flute we accept: broaching step t = 10 mm; groove depth h = 3.6 mm; back surface length b =4 mm; groove radius r = 2 mm.
The pitch of the calibrating teeth tk of round broaches is taken equal to 0.6-0.8 from t,
tk=0.8·t=0.8·10=8 mm.
We select the geometric elements of the blade of cutting and calibrating teeth according to:
γ=15º; α=3º - for roughing and transition teeth,
γ=20º - for finishing and calibrating teeth,
α=2º - finishing teeth,
α=1º - calibrating teeth.
The number of chip separating grooves and their sizes are selected according to. Number of grooves n=22mm, m=0.6mm, hк=0.7mm, r=0.-0.3mm. Distance between grooves,
bк=πD/n=(3.14·45)/16=6.9mm,к’=0.4 bк=0.4·6.9=2.76mm,
The maximum deviation of the front angles of all teeth is +2°, the rear angles of the cutting teeth are +30°, the rear angles of the calibrating teeth are +15°.
Maximum number of simultaneously working teeth:
Determine the dimensions of the cutting teeth. The diameter of the first tooth is taken equal to the diameter of the front guide part, i.e.:
D3=D-A=45-0.8=43.7 mm.
The diameter of each subsequent rough tooth will increase by two thicknesses of the cut layer, i.e.
Dn=D1+(n-1)2Sz
Between the cutting and calibrating teeth we make cleaning teeth with a constantly decreasing rise per tooth. The thickness of the cut layer with each stripping tooth decreases from the first to the last.
The diameter of the calibrating teeth is equal to the diameter of the last rough tooth, Dк=Dmax+-δ=45.025-0.009=45.034 mm,
where δ is the change in hole diameter after broaching; for broaching steel workpieces, the increase in hole diameter is 0.005-0.01 mm, taking it equal to 0.01 mm.
We summarize the calculated tooth sizes in a table. The maximum deviations of the diameters of the cutting teeth should not exceed 0.01 mm, and of the calibrating teeth 0.005 mm. Diameter, mm, broach teeth
|
Tooth diameter, mm |
Tooth diameter, mm |
Tooth diameter, mm |
|||
The number of cutting teeth is calculated using the formula:
where A is the allowance for broaching;
we accept zp=24.
The number of calibrating teeth depends on the type of broach: for spline broach we take Zк=6.
The length of the broach from the end of the shank to the first tooth is taken depending on the size of the chuck, the thickness of the base plate, the device for securing the workpiece, the gap between them, the length of the workpiece and other elements:
lo=lв+lз+lс+lн+lп,
where lв is the length of the shank entry into the chuck, depending on the design of the chuck (we assume lв = lxв =120 mm); h - the gap between the chuck and the wall of the machine support plate, equal to 5 - 25 mm (we assume lз = 25 mm); c - thickness walls of the support plate of the broaching machine (assuming 1s = 42 mm); p - height of the protruding part of the faceplate (assuming lп = 30 mm); n - length of the front guide (taking into account the gap Δ); lн = 90mm.
lo = 120+25+42+ 30+90 = 320 mm.
Then we check the length 10 taking into account the length of the drawn workpiece: 1о>Lс, since h" = lд = 90 mm, then
Lс = 220+ h" = 220+90 = 310 mm.
≥310, therefore, the condition is met.
We determine the structural dimensions of the tail part of the broach. According to GOST 4044-70* we accept a type 2 shank, without rotation protection with an inclined supporting surface: d1=22e8(-0.046-0.073) mm; d2=17c11(-0.110-0.240) mm; d4=22-1=21 mm; c=1 mm; 11=130 mm; 12=25 mm; 13=60 mm; 14=16 mm; r1=0.3 mm; r2=1 mm; α=30º; front guide diameter d5=24e8(-0.040-0.073); the length of the transition cone is structurally assumed to be lк=65 mm; length of the front guide to the first tooth lн=lи+25=90+25=115 mm; thus the total length of the shank
l0=l1+lк+lн=140+65+115=320 mm.
The diameter of the rear guide broach must be equal to the diameter of the drawn hole with a maximum deviation of f7.
Determine the total length of the broach:
Lo= lo+ lр+ lzach+ lк+ lzn
where lo = 320 mm;
p - length of cutting parts,
р = tzр = 10·23=230 mm;
zach - length of stripping teeth; lzach = tzzach = 10·3 = 30 mm;
k - length of calibrating teeth; lк = tк zк = 0.8·7 = 5.6 mm;
zn - length of the rear guide,
1з=(0.5-0.75) 1д=0.6·90=60 mm.
Then,
Lo = 320+230+30+5.6+60 = 645mm.
Condition check: Lо< Lстанка.
Because Lmachine = 1500 mm, the condition is met.
Maximum permissible main component of cutting force max=9.81·Cp·Szx·DZmax·ky·kc·ki
Correction factors for changed cutting conditions: ky=1 (for γ=15º); kc=1 (when using coolant); ki=1 (for broach teeth with chip separating grooves); then cutting forcemax=9.81·700·0.03 0.8525·8=70,000 N (≈7,000 kgf)
The main component of the cutting force can be determined using the literature. The resulting force Pz max should not exceed the traction force of the machine, in this case it is equal to 10,000 kgf, therefore, processing is possible.
F1==0.78·(22-17)=153 mm,
Where does the permissible stress during crushing come from?
σхв = MPa,
The permissible crushing stress should not exceed 600 MPa, which is fulfilled
We select maximum deviations for the main broaching elements and other technical requirements in accordance with GOST 9126 - 76.
We make center holes according to GOST 14034 - 74, form B.
3.3 Calculation of cutting mode when broaching:
We set the machinability group - U10A with hardness HB202 belongs to the first machinability group.
The quality group of the drawn surface is determined by quality and roughness parameter: hole quality H 7,
Select the type of coolant. For cast iron we use coolant - sulfolfreserol. (Symbol in map “B”).
Maximum cutting force Pz max = 63679 kgf/mm2.
For round broaching of the second quality group and the first group of machinability and mass production, we accept V = 8m/min. Correction factor for speed, because broach made of high-speed steel R18.
Conclusion
In this course work, calculations were made for the following tools: a round shaped cutter, a round broach, a worm cutter and a solid reamer.
In the process of performing this course work, technical reference literature was used, cutting modes for cutting tools were calculated, analytical and graphical methods of calculation and construction were carried out.
Currently, the share of metal cutting in mechanical engineering is about 35% and, therefore, has a decisive influence on the pace of development of mechanical engineering as a whole.
Literature:
1. Nefedov N.A., Osipov K.A.. Collection of problems and examples on cutting metals and cutting tools. - M.: Mechanical Engineering, 1990.
Handbook of mechanical engineering technologist T.2 / ed. A.N. Malova
Arshinov V.A., Alekseev G.A. Metal cutting and cutting tools. M.: Mechanical Engineering, 1968. - 500 p.
Gaponkin V.A., Lukashev L.K., Suvorova T.G. Machining, metal-cutting tools and machines. M.: Mechanical Engineering, 1990. - 448 p.
Rodin P.R. Design and production of cutting tools. -Kiev: Technology, 1968.-358 p.
Paley M.M. "Technology and automation of tool production." - Volgograd, 1995. - 488 p.
Alekseev G.A., Arshinov V.A., Krichevskaya R.M. "Tool Design" 1979.
Anuriev V.I. Handbook of mechanical engineering designer. In 3 volumes. 8th edition revised and expanded. Edited by I.E. Zhestkova - M.: Mechanical Engineering, 2001
Baranchikov V.P., Borovsky G.V. and others. "Handbook of the designer-toolmaker". 1994.
Baranchikov V.I. and others. “Progressive cutting tools and metal cutting modes.” Directory. - M.: Mechanical Engineering, 1990.
Inozemtsev G.G. "Design of metal-cutting tools." - M.: Mechanical Engineering, 1984.
Kirsanov G.N. and others. "Guide to the course design of metal-cutting tools." - M.: Mechanical Engineering, 1986.
3. Kosilova A.G., R.K. Meshcheryakova. "Handbook of machine builder technologist", volume 1, 2. -M.: Mashinostroenie, 1985.
3.1. BASIC CONCEPTS AND CLASSIFICATION OF INCISERS
Cutters with a shaped cutting edge are used to form the surfaces of bodies of revolution and prismatic parts, surfaces that have a line as a generator, representing a combination of straight and curved sections.
Obtaining a shaped surface of a part is possible by separately processing each of the sections of its generatrix using cutters, cutters, grinding wheels, but under the indispensable condition of their (sections) relative arrangement, which ensures obtaining a given profile of the generatrix of the part with the required accuracy. This processing option has a number of disadvantages: reduced process productivity, difficulty in obtaining the required location of treated areas, i.e. the accuracy of the profile of the generatrix of the processed part, and, finally, the need to use the labor of a highly qualified worker. This limits its use: it is used in conditions of single production of parts or in cases where it is impossible to obtain a profile at the same time due to its complexity, increased perimeter and other reasons.
The shaped surfaces of prismatic parts can be processed simultaneously along the entire profile of their generatrix by milling, broaching, grinding, and planing with a shaped cutter. The latter method, as it is low-productive, is rarely used. Some of its features make it possible to successfully use planing shaped cutters when producing simple shaped surfaces of considerable length.
Obtaining a generatrix shaped surface of bodies of rotation simultaneously along the entire perimeter is used in serial and mass production. This option of profiling provides, in comparison with the option of profiling by sections, an increase in processing productivity, an increase in the accuracy of the profile of parts and their identity in profile, which is carried out using shaped tools: cutters, broaches, grinding wheels, shaped cutters. Each of these methods has its own characteristics and indicators of productivity, accuracy, cost and other data, depending on the conditions in which they are used.
In mechanical engineering, there are parts of such sizes and such processes for their production that the use of milling, broaching and grinding is inappropriate and the use of shaped cutters is preferable. Precisely manufactured shaped cutters, when correctly installed on machines, provide high productivity, accuracy of shape and size of processed parts according to IT8...IT12 and a surface with = 0.63…2.5 µm. They also have such advantages as: low metal consumption of the structure, long service life, ease of sharpening and regrinding, manufacturability of the design, relatively low cost, they do not require highly qualified workers for operation. Shaped cutters are used on lathes, turrets and automatic machines, i.e. on the same machines on which such parts are preprocessed. The presence of grinding machines for profiling shaped cutters increases the manufacturability of their manufacture and contributes to their wider use.
Like other metal-cutting tools, shaped cutters are characterized by a number of features that are used to classify them. Shaped cutters can be divided into the following groups: by shape - rod, prismatic and round cutters; by type of surface being treated - external and internal; by installation relative to the workpiece and the direction of feed movement - radial and tangential; according to the location of the cutter relative to the part - with parallel and angled axes or a measurement base; according to the location of the front surface - without tilt ( λ = 0) or angled λ ; according to the shape of the forming shaped surfaces - ring and screw.
