Unified Tariff and Qualification Directory of Works and Professions of Workers (ETKS), 2019
Part No. 1 of issue No. 2 ETKS
The issue is approved by the Decree of the Ministry of Labor of the Russian Federation of November 15, 1999 N 45
(as amended by the Order of the Ministry of Health and Social Development of the Russian Federation of November 13, 2008 N 645)
Roller
§ 72. Roller of the 3rd category
Job Description. Hot rolling of blanks of rings for bearings with a diameter of up to 250 mm on rolling machines in compliance with the established dimensions. Checking dimensions with a measuring tool. Machine tuning.
Must know: device and methods for adjusting serviced rolling machines and an electric heating device; steel grades used for ball bearing rings; purpose and conditions for the use of control and measuring instruments.
§ 73. Roller of the 4th category
Job Description. Hot rolling of ring blanks for bearings with a diameter of more than 250 to 350 mm on rolling machines and blanks into a conical disk for car wheels on a disk rolling mill. Mill adjustment. Hot rolling of blanks of rings for bearings with a diameter of more than 350 mm on rolling machines together with a higher qualification roller.
Must know: the device of the disk rolling mill and the kinematic diagrams of the serviced rolling machines; steel grades used for rolling blanks of machine wheel disks; temperature and mode of heating of blanks; device of control and measuring instruments.
§ 74. Roller of the 5th category
Job Description. Hot rolling of blanks for bearing rings with a diameter of more than 350 mm, profile rings and spherical shells of variable thickness from heat-resistant and titanium alloys of aircraft engines with a diameter of up to 1500 mm on rolling machines. Nozzle of rolling machines on rings.
Must know: kinematic diagrams of various rolling machines, disk rolling mill and heating devices used for rolling rings and spherical shells; optimal modes of heating billets; allowances and tolerances during processing; dependence of the degree of radial compression on the thickness at various points of the workpiece; ways to adjust rolling machines.
§ 75. Roller of the 6th category
Job Description. Hot rolling, straightening, calibration of profile rings and spherical shells of variable thickness from heat-resistant and titanium alloys of aircraft engines with a diameter of more than 1500 mm on rolling machines. Rolling thin-walled parts from corrosion-resistant steels and molybdenum alloys.
Must know: technological process of rolling large-sized and thin-walled parts; design of kinematic, hydraulic and heating devices and methods for their adjustment; ways to achieve the established accuracy of processing; rules for calculating parabolic shells associated with the performance of various works.
1. STATE OF THE QUESTION AND FORMULATION OF RESEARCH PROBLEMS.
1.1 Applications of ring products in modern industry
1.2 The main methods of manufacturing aircraft GTE rings.
1.3 Experimental methods for studying the deformation zone.
1.4 Analytical methods for studying the deformation zone during rolling and rolling.
1.5 Application of the finite element method to study the deformation zone during rolling and rolling.33.
1.6 Brief description of KhN68VMTYUK-VD and KhN45VMTYuBR-ID alloys and the mechanism of their recrystallization.
1.7 Review of studies of the thermal state of the metal in the deformation zone during ring rolling and flat rolling.
2. DETERMINATION OF THE DEPENDENCE OF THE FRACTION OF THE RECRYSTALLIZED VOLUME ON THE TEMPERATURE OF THE DEGREE OF DEFORMATION AND THE TIME OF THE INTERDEFORMATION PAUSE FOR ALLOYS KhN68VMTYUK-VD AND
KhN45VMTYuBR-ID.
2.1 Analysis of the mechanism of shaping during hot rolling of GTE rings.
2.2 Goals and methodology of the experiment.
2.3 Equipment and instruments for research.
2.4 Study of the process of primary recrystallization in KhN68VMTYUK-VD and KhN45VMTYuBR-ID alloys after hot deformation.
3. DEVELOPMENT OF A MATHEMATICAL MODEL OF THE PROCESS OF HOT ROLLING OF GTE RING PARTS.
3.1 Basic assumptions and hypotheses.
3.2 Mathematical description and discretization of the solution area.
3.3. Approximation of displacement, strain and stress fields.
3.3.1 Approximation of displacements in an element.
3.4. Compilation of local global stiffness matrices. The main system of equations of the finite element method.
3.4.1 Construction of a local stiffness matrix.
3.4.2 Building a global stiffness matrix.
3.4.3 Accounting for boundary conditions.
3.5. Building a temperature field model.
3.6. General structure of the mathematical model.
4. INVESTIGATION OF THE INFLUENCE OF INTERDEFORMATIONAL PAUSES ON THE VALUE OF ACCUMULATED STRAIN AND TEMPERATURE DURING ROLLING GTE RINGS.
4.1 Description of the stages of rolling of GTE rings.
4.2 Search for optimal reduction modes and the duration of the interdeformation pause during hot rolling of GTE rings.
4.3 Comparison of simulation results with experimental data.
4.4 Checking the found results with a thermal imager
4.5. Industrial study of ring rolling modes with regulation of the interdeformation pause.
5 SEARCH FOR OPTIMAL MODES OF LOCAL COMPRESSIONS AND SPEEDS OF THE DEFORMING TOOL DURING ROLLING GTE RINGS.
5.1 Determining the allowable deformation time.
5.2 Selection of the optimal rotation speed and local reductions.
Recommended list of dissertations
Optimization of technological regimes of deformation of large-sized ring blanks from hard-to-deform heat-resistant steels and alloys 1999, Candidate of Technical Sciences Mints, Alexander Ilyich
Development of a highly efficient resource-saving technology for the production of rings from heat-resistant alloys based on the study of the upsetting process of workpieces 2013, candidate of technical sciences Batyaev, Daniil Vladimirovich
Optimal control of a non-stationary object with distributed parameters and moving action 1999, candidate of technical sciences Chuguev, Igor Vladimirovich
Research, development of equipment and mastering the technology of cold rolling of bearing rings 1998, candidate of technical sciences Kishkin, Ivan Vasilyevich
Simulation of the deformability of continuously cast steel in order to improve the rolling of billets 1999, candidate of technical sciences Antoshechkin, Boris Mikhailovich
Introduction to the thesis (part of the abstract) on the topic "Development of a methodology for calculating the accumulated deformation during hot rolling of GTE rings, taking into account interdeformation pauses"
Relevance of the topic. Gas turbine engines (GTEs) are widely used in aircraft and gas pumping stations. Today, the level of competition is high in domestic and foreign engine building. Therefore, enterprises engaged in the production of gas turbine engines strive to ensure that their products meet the highest requirements for the most important performance characteristics. The operational reliability and other important parameters of a gas turbine engine depend mainly on how high the quality of its component parts is.
One of the most important parts in engine building are GTE rings that serve as connecting elements. The failure of at least one ring can lead to a breakdown of the entire engine, i.e. an emergency. Therefore, the annular parts of aircraft gas turbine engines operating at high temperatures and dynamic loads are subject to high requirements for structural uniformity and the level of mechanical properties. One of the main ways to obtain ring parts is hot rolling from a forged billet. A characteristic disadvantage of this process is the appearance in the annular part during the final heat treatment of areas with large grains, which are the result of the metal obtaining critical values of the degree of plastic deformation. The uneven-grained structure of the ring, in turn, leads to a sharp decrease in the level of mechanical properties and the service life of these parts under difficult operating conditions.
The appearance of zones with large grains in the annular blank is facilitated by the fragmentation of deformation during rolling. In fact, ring rolling is a set of local deformation acts in which hardening occurs. Between these local acts, an interdeformation pause occurs in which partial recrystallization is observed and strain hardening is removed. A decrease in the degree of strain hardening, in turn, contributes to the formation of zones with large grains during the final heat treatment of the ring.
The purpose of this work is to improve the technological modes of hot rolling of GTE annular parts based on the developed finite element model for calculating the accumulated deformation, taking into account the temperature and speed parameters of deformation, the duration and number of interdeformation pauses
To achieve this goal, it is necessary to solve the following tasks:
1. Determine the dependences of the change in the proportion of the recrystallized volume of the ring blank on the heating temperature, the degree of deformation and the time of the interdeformation pause for KhN68VMTYUK-VD and KhN45VMTYuBR-ID alloys (typical materials for GTE rings).
2. Develop a finite element model for calculating the values of the degree of deformation accumulated during the rolling process, taking into account the heating temperature of the workpiece, the magnitude of local reductions and the duration of each interdeformation pause.
3. On the basis of the developed mathematical model, to investigate the effect of the billet heating temperature, the magnitude of local reductions, the duration and number of interdeformation pauses on the degree of accumulated deformation over the entire rolling cycle.
4. To develop recommendations on the choice of temperature-speed and deformation modes of hot rolling, the number and duration of interdeformation pauses, providing the calculated values of the accumulated deformation, the homogeneity of the macrostructure and the required level of mechanical properties of ring blanks.
5. Conduct a pilot test of the adequacy of the developed technological modes of hot rolling of ring parts to the requirements for macrostructure and level of mechanical properties.
The scientific novelty of the work is as follows:
1. The process of hot rolling of GTE rings is considered as a process with fractional deformation, consisting of multiple local compressions and subsequent multiple acts of partial recrystallization in interdeformation pauses.
2. A finite element model has been built that allows to investigate the hot rolling of ring blanks, taking into account the heating temperature of the metal, the degree of local reductions and the duration of interdeformation pauses.
3. The dependences of the change in the proportion of the recrystallized volume of the ring billet made of KhN6 8VMTYuK-VD and KhN45VMTYuBR-ID alloys (typical materials for GTE rings) on the heating temperature, the degree of deformation, and the time of the interdeformation pause are established.
4. Using the ThermaCAM P65 thermal imager, the thermal field was studied during the rolling of GTE rings and the optimal duration of the deformation process was established.
The reliability of the scientific results of the research is confirmed by the use of the most accurate and modern method of studying plastic media (finite element method) for modeling, the use of a software product in the modern C + language for the implementation of the model, as well as a wide range of experimental studies.
Research methods. Studies of the stress-strain state during the rolling of GTE rings were carried out using a finite element model, on the basis of which a software product in the C + language was created. Experimental studies included the upsetting and etching of samples from KhN68VMTYuK-VD and KhN45VMTYuBR-ID alloys and the study of their macrostructure using an Axiovert 40 MAT instrument. The experimental rolling of the ring was carried out on a rolling machine RM1200, followed by cutting out samples from the ring blank and studying the mechanical properties on a TsTSMU 30 stretching machine and macrostructure using an Axiovert 40 MAT device. The temperature field was studied using a ThermaCAM P65 thermal imager.
The author defends a finite element mathematical model that allows one to analyze the process of rolling out of GTE rings, taking into account the fractional deformation. Established patterns of change in the proportion of recrystallized volume on temperature, degree of deformation and time of the interdeformation pause for KhN68VMTYUK-VD, KhN45VMTYuBR-ID alloys. Distribution of local reductions and speed of rotation of the drive roll during the rolling of the GTE rings, providing the specified values of the degree of accumulated deformation. Experimental studies of the thermal field, deformable annular workpiece.
The practical value of the work.
1. On the basis of the developed mathematical model, the problem of determining the values of the degree of deformation accumulated over the entire rolling cycle, depending on the specific process parameters, was solved, which makes it possible to ensure its optimal values before the final heat treatment.
2. Recommendations have been developed for choosing the optimal temperature and speed modes for local reductions of the annular billet, taking into account the feed rate and speed of rotation of the drive roll, which ensure the uniformity of the structure and high mechanical properties.
3. The results obtained in the dissertation were used in OJSC "Motorostroitel" and OJSC SNTK "NES Engines" named after. N.D. Kuznetsov during the development of technology for hot rolling of ring blanks from KhN68VMTYUK-VD and KhN45VMTYuBR-ID alloys
Approbation of work. The main results of the work were reported and discussed at the following conferences: Royal Readings (Samara, 2007), All-Russian Scientific and Technical Conference of Students "Student Spring 2008: Engineering Technologies" (Moscow, 2008), Reshetnev Readings (Krasnoyarsk, 2008). International Scientific and Technical Conference "Metal Physics, Mechanics of Materials, Nanostructures and Deformation Processes" (Samara, 2009) Publications. 6 papers have been published on the topic of the dissertation, including 2 articles in leading peer-reviewed journals and publications recommended by the Higher Attestation Commission.
Structure and scope of work. The dissertation work consists of an introduction, four chapters, main results and conclusions, a bibliography of 133 titles, contains 138 pages of typewritten text, 58 figures, 3 tables.
Similar theses in the specialty "Technologies and machines for pressure treatment", 05.03.05 VAK code
Research, development and implementation of effective technologies for the production of strips and strips from steel and non-ferrous metal alloys with desired structure and properties 2011, Doctor of Technical Sciences Aldunin, Anatoly Vasilyevich
Improving the technology of manufacturing rings from titanium alloy VT6 by determining rational deformation modes 2017, Candidate of Technical Sciences Alimov, Artem Igorevich
Establishment of the features of hot rolling of large-sized ingots from complexly alloyed copper alloys in order to improve the quality of strips 2003, candidate of technical sciences Shimanaev, Alexander Evgenievich
Mathematical modeling and optimization of materials deformation processes during pressure treatment 2007, Doctor of Physical and Mathematical Sciences Logashina, Irina Valentinovna
Technological process of hardening semi-hot thermomechanical treatment during forging stamping 2013, Ph.D. Fomin, Dmitry Yurievich
Dissertation conclusion on the topic "Technologies and machines for pressure treatment", Aryshensky, Evgeny Vladimirovich
MAIN RESULTS AND CONCLUSIONS
1. A mathematical finite element model has been developed for hot rolling of GTE rings, taking into account the fractional nature of deformation, which makes it possible to determine the temperature of the workpiece, the degree of accumulated deformation and take into account the influence of local reductions and interdeformation pauses on these parameters.
2. Regularities have been established for the change in the proportion of the recrystallized volume of the ring billet depending on the temperature of rolling, the degree of deformation and the duration of the interdeformation pause for KhN68VMTYUK-VD and KhN45VMTYuBR-ID alloys.
3. At each stage of shaping, the values of the heating temperature, the degree of local reductions, and the duration of the interdeformation pauses necessary to obtain the calculated value of the accumulated deformation in the annular workpiece before the final heat treatment are established.
4. Comparison of the data obtained by modeling and experimentally shows high convergence and confirms the adequacy of the developed finite element model.
5. In general, on the basis of meta-mathematical modeling, science-based technological modes of hot rolling have been developed with regulated values of the deformation temperature, rotation speed and drive roll feed rate, ensuring the homogeneity of the macrostructure and increasing the strength properties of the annular parts of the gas turbine engine by 8 - 10% and plastic by 15 - 21%.
6. Due to the increase in the reliability and durability of the annular parts of the GTE during the operation of the NK-32 engine, the total economic effect of the implementation amounted to 1,000,000 million rubles for each engine
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The end rolling method makes it possible to produce forgings from alloyed and non-alloyed steels weighing from 0.5 to 150 kilograms, with a diameter of up to 1000 mm. The configuration of blanks is as close as possible to the configuration of finished products. Machining allowance is no more than 5mm. The current modern technology makes it possible to obtain forgings with a variety of configurations and having a structure and properties that ensure their use in the most difficult loading conditions, the service characteristics of products in terms of fatigue strength increase from 1.5 to 6 times. Metal is saved, labor intensity is reduced, and quality is improved and operational reliability of products. The blanks after forging by rolling fully correspond to the term "precise blanks of parts".
Induction heating METHOD FOR END ROLLING OF FORGINGS BY THE END ROLLING OF THE "BODY OF REVOLUTION"
The process of manufacturing the product goes through a multi-stage research preparation. To assess the quality of the material, preliminary tests are carried out. In the course of studying the terms of reference, it is taken into account where this product will be used, what technological processing it will be used for. Drawings, design documentation undergo a series of control approvals with the customer, and only after that prototypes are made. It is impossible to achieve high quality products in mass production, when the order volume can reach up to 2,000 -3,000 pieces of forgings, without careful preparation of production and well-developed technology. For the development of each new product, our approach is exclusively professional.
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At present, the following types of forgings have been mastered
Sleeve Piston core Valve plate Pin
Pump bushing to China st.70 (IMPORT SUBSTITUTION) Pump bushing 8T650 st.70 (IMPORT SUBSTITUTION) t.70 Gear block st.40X Gear block 2 st.40X Gear block 3 st.40X
Ring st.40X Plate st.20KhGNM Stepped gear st.40X Flange made of st.
Gas pipeline flange (РH16-160) st.40X, 09G2S, 20 BRS connection st.45 Hollow shaft (Sleeve) Railway st.45 Valve plate st.40khn2ma Pump piston core st.40X
Axial fan flange Piston core 2 Fan hub st Washers for gas pipelines st.40X Rolling stock fan hub Railway
UDC 621.73
FINITE ELEMENT MODEL FOR CALCULATION OF THE VALUE OF ACCUMULATED STRAIN IN THE PROCESS OF HOT ROLLING OF RINGS
© 2009 F.V. Grechnikov1, E.V. Aryshensky1, E.D. Beglov2
1 Samara State Aerospace University 2 OJSC "Samara Metallurgical Plant"
Received February 13, 2009
A finite element model for calculating the degree of accumulated deformation at various stages of deformation of an annular blank has been developed. Comparison of simulation results and experimental dependencies confirms the adequacy of the model.
Key words: ring rolling, macrostructure, recrystallization, accumulated strain, finite element method, model, stiffness matrix, equal-strength inserts.
In the practice of GTE production, ring parts with multifunctional purposes are widely used. High demands are placed on these parts in terms of structure and level of mechanical properties. The main way to obtain ring parts is hot rolling (Fig. 1). A feature of this process is the presence of multiple acts of local deformation of the workpiece at the time it is in the rolls and the accompanying multiple partial recrystallization in interdeformation pauses, which makes it difficult to calculate the total (cumulative) deformation for the process.
This leads to the fact that along the section of the workpiece there can be simultaneously different degrees of deformation, including critical degrees of deformation. In turn, critical degrees of deformation contribute to the formation of coarse grains during the final recrystallization annealing. At the same time, in places where the deformation exceeded critical values, a fine-grained structure will form. Thus, the inhomogeneity of deformation leads to inhomogeneity, i.e., structural inhomogeneity over the section of parts and a decrease in the level of mechanical properties. To avoid this, it is necessary to know at each stage the value of the accumulated deformation obtained by the metal both at each local stage of deformation and for the entire period of rolling as a whole. In this regard, the purpose of this article is to build a mathematical model that allows you to determine the stress-de-
Grechnikov Fedor Vasilyevich, Doctor of Technical Sciences, Professor, Corresponding Member of the Russian Academy of Sciences, Vice-Rector for Academic Affairs. Email: [email protected] Aryshensky Evgeny Vladimirovich, post-graduate student. Email: [email protected]
Beglov Erkin Dzhavdatovich, candidate of technical sciences, leading engineer. Email: [email protected]
the formed state and the magnitude of the degree of accumulated deformation.
When developing the finite element model, it was taken into account that, due to symmetry, the structure and properties of the rolled ring are identical for all sections along the circumference. Considering this circumstance, the model was built not for the entire ring, but for a segment equal to 6 lengths of the deformation zone. The segment is divided into triangular finite elements, as shown in Fig. 2.
The angle p, which determines the position of the element in the solution area, is found by the following formula.
12 1 ■ kg
(2YAN + 2YV) , (1)
where YAN, YB - outer and inner radii of the ring;
K - the average radius of the ring in 1 turn.
b is the length of the arc of contact with any of the rolls. To determine it, the formula is applied
b 1(2) AN, (2)
Rice. 1. Scheme of the process of hot rolling of rings: 1 - workpiece, 2 - internal non-drive roll (mandrel), 3 - external drive roll, 4, 5 - guide rollers, 6 - limit switch (diameter control)
where R2 are the radii of the driven and non-driven rolls
A b - absolute compression First, we divide the solution area into quadrangular sectors, each of which corresponds to two neighboring triangular elements. There are N rows of sectors in the radial direction and M in the tangential direction. There are 2 ■ N ■ M triangular elements and (M + 1) ■ (N + 1) nodes. The numbering of nodes is shown in fig. 2. We denote the coordinates of the 1st node along the axes 1 and 2 as xts, X "2
WCH)] HMMM)| ;<3>
1 EVn.+Dn-Dn then!± ^toD
During the calculation, the coordinates of the nodes at any point in the calculation area will change to
displacement of nodes n, 2 . To find n, 2 we use the energy method . Consider a separate triangular element 1 with nodes 1, 2, 3 in Figure 3.
Let us assume that the element is initially not stressed, the nodal forces are equal to 0. Then the forces A, Y, /3 are applied to the corresponding nodes of the element. New config
The node distribution will have an offset d 11, d "12, d, d22, d ^, d 32. The upper index refers to the element, in the future we omit it. The first lower index refers to the node, and the second to the coordinate. Potential energy I of the new configuration in relation to the original is the difference between the energy of the stressed state accumulated in the element and and the work done by the forces /2,/3 on the displacement vector e, .
I = u-W = 2 |
Fig 3. Setting the boundary conditions in the problem of segment deformation
where e12 ....... - displacements in the nodes of the element
in directions 1,2 respectively;
/p ...... /32 - forces under the influence of which
there is a displacement of nodes in the direction of 1.2, respectively;
e11 e22 - normal, and e12 - tangential components of the strain tensor;
y11y22 - normal, y12 - tangential components of the stress tensor.
The integration is carried out over the volume ^ (in the considered case of plane deformation, over the area of the element dF). For the convenience of further solution, we represent equation (5) in matrix form.
I \u003d - | a -e-eG-e 2
G \u003d 2\eTscheG - \u003d
The values of the components of the vector ё = |ё„ ■■■ ё32|| must be such that the potential energy I has a minimum value:
■- = 0 ; H1...3, . (7)
After differentiation, in vector form we get:
And -ING) -e \u003d f. (eight)
To understand the notation, ||in||, and ||and|| once again consider a separate element presented in Fig.3.
If it is triangular, as in our case, and the stresses in it change linearly, then it is recommended to connect the displacement values of the element nodes and its deformation by the following formula.
X22 X-32 X11 X31 X32 X12 X21 X11
21 Hz 12 22
We write expression (9) in matrix form as follows:
e = \\B\\ - e. (9 a)
As can be seen from (9) ||in|| expresses changes in the coordinates of the nodes of a triangular element while maintaining its area and connects the displacement in its nodes with the accumulated deformation.
In turn ||and|| expresses the relationship between the strain tensor and the stress tensor. Its values are different for the elastic and plastic states. Output ||And|| for both states
yany can be found in . Here its values are given, and only for plane deformation and the energy approach. Elastic deformation:
1 + V 1- - 2v 1 - 2v
Plastic state:
)- ee = |I| - ee, (12)
for the elastic part of the deformation, for the plastic part of the deformation.
a11 a11 a11 0 22 ^ a11 012
a22 a11" 0 22 0 22 0 22 a12
a12 a11 a12 0 22 a12 012
where shear modulus O =
8 - characteristic parameter of the elastic-plastic state
This parameter makes it possible to take into account the dependence of stresses on deformation and other process parameters, which are expressed through a relation of the form
0 = 0(e, e, T, a in c), (17)
where e is the accumulated strain under uniaxial compression (tension);
e - strain rate; T - temperature;
aoa a, b, c - empirically determined ratios. The search for such relationships is dedicated to
but a lot of research. We have used the results for alloys used in the rolling of GTE rings.
Let us return to formula (8), which, as is now clear, expresses the relationship between the force in the element, on the one hand, and stress, deformation, and displacement, on the other. Eliminating displacements from formula (8), we denote its left side as follows.
W = M-|I-B-dF- (18)
U is the stiffness matrix. It takes into account all the deformation parameters given above. If this matrix is given for one triangular element, it is called local. The global matrix will be the matrix of the right side of the system (M ++1) of equations, formed as the algebraic sum of the local matrices of each element.
It should be noted that we already know the voltage
For a non-driven roll, in the first half of the capture arc, the forces are directed against the direction of metal movement, in the second - in the direction of movement (Fig. 3, b). For each node in contact with the roll, the direction of the forces is known. P - normal pressure, t = juP - friction force, j - coefficient of friction.
Consider equation (19), which in expanded form for node 9 can be written as follows (Fig. 3b).
k17.17 d91 + k17.18 d 92 + k17.19 d101 + k17.20 d102 +
K17.21 d111 + k17.22 d112 = f91 =
JP cos (p3 - P sin (p3, (20)
k18.17 d91 + k18.18 d92 + k18.19 d101 + k18.20 d102 +
K18.21d111 + k18.22d112 = f92 =
P sin (p3 + /uP cos (p3. (21)
When solving equations (20) by the Gauss method, we take into account the condition of non-penetration of the workpiece material into the non-driven roll:
d91 ■ sin (p3 = d92 ■ cos^3. (22)
This condition will allow us to exclude from the system of equations (19) d92 We perform this transformation for all equations containing nodes lying on the surface of the non-driven roll.
On the drive roll, the speed of rotation is known, but the mutual displacement of the surfaces of the metal and the roll is unknown. Let's apply the following method.
Let's introduce a fictitious layer of elements. Let's show it on the example of an element with nodes 7, 6 (Fig. 3a). These nodes move as rigidly connected to the roll. The nodes of the contact layer of metal 5 (Fig. 3 a) move along the surface of the roll. The element stiffness matrix K is modified using the friction index m. The elements of the stiffness matrix are multiplied by m / m - c. At
m tending to 0, the element becomes stiffer, simulating low friction. For m ^ 1, the "sticking" of the material to the rolls is simulated. The elements do not model the lubrication layer, but model the action of the lubrication. Each element of the fictitious layer is created at the time of construction of the corresponding real element. Matrices of real and fictitious elements can be compared and jointly solved in equation (8). The movements of the fictitious nodes are known, i.e. they move as rigidly connected to the roll.
Equations (19) for node 5 (Fig. 3 a) will have the following form.
k9 3d 23 + k 9.4d 22 + k9.7 d41 + k9.8 d42 + k9.9 d51 + + k 9.10 d52 + k 9.15 d 81 + k9.16 d82 + k 9.13 d71 + + k 9.14d 72 + k 9.11 d61 + k 9.12 d62 = f51 , (23)
k10.3 d 21 + k10.4d 22 + k10.7 d41 + k10.8 d42 + k10.9 d51 + + k10.10 d 52 + k10.15 d 81 + k10.16 d 82 + k10.13 d71 + + k10.14d72 + k10.11d61 + k10.12d62 = f52 . (24)
Since the force in node 5 is normal to the roll surface, we have:
f2Cos^2 = fs1sin (Р2, (25)
The condition of non-penetration of the roll surface ds1 cos^2 = ds2 sin (p2, (26)
When compiling the global stiffness matrix, transforming equations (23, 24) taking into account (25,
Rice. Fig. 4. Arrangement of equal-strength inserts in the deformation zone during rolling. H0 is the thickness of the billet before it enters the rolls; y, x - values of insertion coordinates;
a0, b0 and ax, bx
initial and final sizes of inserts, respectively
52, yb1, you can also use
26), excluding /51, /5, is called when solving system (19) by the Gaussian elimination method. During the solution, the values of the accumulated strain, stresses and displacements are found, i.e. the stress-strain state in the deformation zone.
The adequacy of the model is verified on the basis of experimental studies of the rolling of rings given in the work. In this work, we studied the deformation zone of a ring made of aluminum alloy AMg6, in which
holes were drilled in layers and filled with inserts of the same metal (Fig. 4). The rolling of rings with an outer diameter of 400 mm, an inner diameter of 340 mm and a thickness of 30 mm was carried out on a ring rolling mill model PM1200 with work roll diameters: upper drive roll - 550 mm and lower non-drive roll - 200 mm; the maximum feed rate of the pressure device was 16 mm/sec.; the rolling speed provided by the design of the mill corresponded to 1.5 m/sec. According to the results of measuring the inserts, the values were found
"h T| /) / [>
___^ S.GChS1 IG I /1^1111.1С
¿■¡i nt I a
V no|en.nch I data
5vep;rsks t;
anspro-."and that
SgU 1, and inm?
S: h: "ini 2 ^ I member MZDSL.-fEBaMN!
■I l -I l and e. 2 v. I 11 and. 7VSH1 V ■DIM [-1
Rice. Fig. 5. Distribution of strain intensity over the height of the strain zone during rolling of an annular specimen made of AMg6 alloy: e1 is the degree of accumulated strain, y is the coordinates of the point along the y-axis (Moreover, Ho/2 corresponds to 1 on the y-axis)
deformations and stresses, which are presented in fig. 5. The presented experimental data on the rolling of an AMg6 alloy ring were introduced into the developed finite element model. On fig. Figure 5 compares simulation results and experimental data.
As can be seen from the graph, the results of the experiment and simulation are almost identical (convergence is about 15%).
1. To form a homogeneous macrostructure and the required level of mechanical properties in the annular parts of the GTE, it is necessary to control the amount of the accumulated degree of deformation at each stage of the hot rolling of the billet.
2. A finite element model has been developed
the ratio of the degree of accumulated deformation at various stages of deformation of ring blanks.
3. Comparison of simulation results and experimental dependencies confirms the adequacy of the model.
BIBLIOGRAPHY
1. Lakhtin Yu.M., Leontieva V.P. Metal science. M.: Mashinostroenie, 1980. 493 p.
3. Tselikov A.I. The theory of force calculation in rolling mills. - M.: Metallurgizdat, 1962.
2. Finite-element plasticity and metalforming analysis / G.W. Rove., C.E.N. Sturgess, P. Hartly., Cambridge University Press, 2005. 296 pp.
4 P.I. Polukhin, G.Ya Gun, A.M. Galkin Resistance to plastic deformation of metals and alloys. , M. Metallurgy, 1983, p. 353
5 Kostyshev V.A., Shitarev I.L. Ring rolling. - Samara: SGAU, 2000. S. 206.
THE FINAL-ELEMENT MODEL CALCULATION SIZE SAVED DEFORMATION IN THE PROCESS OF HOT ROLLING RINGS
© 2009 F.V. Grechnikov1, E.V. Aryshensky1, E.D. Beglov2
It is developed, is a final-element model of calculation degree the saved up deformation at various stages of deformation of ring preparation. Comparison of results of modeling and experimental dependences confirms adequacy of model.
Key words: rolling rings, macrostructure, recrystallization, the saved up deformation, method of final elements, model, a rigidity matrix, full-strength inserts.
Fedor Grechnikov, Doctor of Technics, Professor, Corresponding Member of Russian Academy of Sciences, Vice Rector for Academic Affairs. Email: [email protected] Evgenie Aryshensky, Graduate Student. Email: [email protected]
Erkin Beglov, Candidate of Technics, Leading Engineer. Email: [email protected]
Union of Soviet
Socialist
Republics
B 21 H 1/Ob with the addition of the application 11ovЂ”
State Committee
USSR for inventions and discoveries (23) Priority
L.N.Dubrovin, V.L.Snitsarenko and I.S.Schenev (71) Applicant (54) DEVICE FOR HOT ROLLING RINGS
The invention relates to the field of metal forming and can be used for hot rolling of rings used, for example, in tractor construction, agricultural engineering, automotive industry and in the production of bearing rings, ring gears, tires, various shells, etc.
A device for hot 10 rolling of rings is known, containing a drive installed in the frame, a drive and non-drive spindles with a rolling tool and a support roller assembly (1 1. 15
In this device, in order to ensure clearance-free fit of the cylindrical surfaces of the tool and its precise fixation in the axial direction, the non-driven roll is fastened to the frame elements by means of a slotted nut with collet petals placed in its grooves.
However, in the specified device 25, the drive outer roll (tool), together with the spindle, must be entirely made of expensive heat-resistant tool steel, which increases the cost of the device 30 and products. A tool made of composite (banded) does not justify itself during hot rolling, since it does not provide a constant tension of the bandage, gap and stability of the rolling process and the quality of the rings and requires an additional technological allowance for subsequent machining.
The aim of the invention is to improve the accuracy of the rings by compensating for the thermal expansion of the tool and ensuring the stability of the rolling process.
The goal is achieved by the fact that the device for hot rolling of the rings is equipped with a compensating device, made in the form of an axially movable conical split sleeve and a membrane preliminarily pressed in the direction of the base of the spindle cone, installed between the spindle and the tool.
In Fig., 1 schematically shows the device, General view; in fig. 2 rolling tool with compensating device; in fig. 3 – support roller assembly.
The device for hot rolling of rings consists of a frame 1, on which a drive spindle 2 is mounted with a rolling tool 3, fixed relative to the frame, and a non-drive spindle
4 with a rolling tool 5 moved relative to the bed by a hydraulic cylinder 6 during the rolling of an annular forging 7. The annular forging is held by a support roller assembly consisting of rollers 8 and 9, kinematically connected to each other by a lever circuit 10 controlled by a hydraulic cylinder 11, fixedly mounted on bed. In the cavity of the hydraulic cylinder there is a piston 12 connected to 15 by the upper rod 13 and the lower rod
The rotation of the drive spindle with a rolling tool is carried out by means of a 15 drive mechanism. Yes. The device is equipped with a compensating device made in the form of a conical split sleeve 16, the cone angle of which is greater than the sum of the angles of friction along its internal surfaces
17 and outer surfaces 18, installed between the tool and the spindle, and the membrane 19, elastically pressed in the direction of the base 20 of the spindle cone with a force less than the force of its ejection during cooling 30 of the rolling tool.
The device works as follows.
Ring stamped forgings of smaller diameter and simple shape 35 in the heated state are installed between the drive 2 and non-drive
4 spindles with rolling tools 3 and 5, and roll out. In the process of rolling the forging, increasing in diameter, the supporting rollers R are pressed out, pressed by the hydraulic cylinder, which ensure the centering of the workpiece and at the same time reduce the vibration of the forging. During the rolling process, the preheated forgings 7 45 gradually heat up the rolling tool, as a result of which a gap is formed between the drive spindle and the tool, however, the compensating device constantly monitors the absence of a gap between the working tool and the spindle, and when it appears, a split sleeve 16 is installed between the rolling tool 3 and drive spindle 2, moves under the action of the membrane
19, elastically pressed in the direction of the base 20, choosing the gap between the spindle and the working rolling tool. The taper angle of the split sleeve 16 is chosen such that it slightly exceeds the angle of self-braking and allows you to smoothly compensate for the formation of thermal radial gaps, and when the tool cools down, return to its original state, while maintaining a constant interference between the rolling tool
3 and the drive spindle 2 under the action of an elastically preloaded membrane 19 with a force that is less than the ejection force of the conical split sleeve 16 when the rolling tool cools down, since the angle of the sleeve cone is greater than the sum of the angles of friction along its inner and outer surfaces.
The proposed device makes it possible to increase the stability of the rolling process and the accuracy of the rings, reduce the technological allowance for subsequent machining, the cost of the working tool and the requirements for the accuracy of its manufacture, as well as reduce equipment downtime. Claims of the invention A device for hot rolling of rings, containing a drive installed in the frame, driving and non-drive spindles with a rolling tool and a support roller assembly, characterized in that, in order to increase the accuracy of the rings by compensating for thermal expansion tool and ensuring the stability of the rolling process, it is equipped with a compensating device, made in the form of an axially movable conical split sleeve installed between the spindle and the tool and a membrane, preliminarily elastically preloaded in the direction of the base of the spindle cone.
