GOST 8732-78 applies to solid rolled pipes that do not have a welded joint, produced by hot deformation on pipe rolling mills - hot-deformed seamless steel pipes. They are significantly superior to their welded alternative counterparts in strength and resistance to deformation. This allows them to be widely used in mechanical engineering, chemical and oil industries and other critical areas.
According to state standards, seamless hot-rolled pipe is manufactured in different dimensional options:
The assortment according to GOST 8732-78 regulates the outer diameters of hot-deformed rolled pipes and the thickness of its walls. Technical requirements GOST 8731-74 establishes for products.
According to the ratio of the size of the outer diameter to the wall thickness (Dн/s), seamless steel pipes manufactured by hot-rolled methods are classified as follows:
Based on quality indicators, solid-rolled hot-deformed pipe products are divided into:
five groups:
A – with standardization of mechanical properties of products;
B – with standardization of the chemical composition of the steel used;
B – control of the mechanical properties of the steel used and its chemical composition;
D – with standardization of the chemical composition of the steel used and mechanical properties products;
D - without standardization of mechanical properties and chemical composition, but with hydraulic tests.
and six classes:
The process of manufacturing pipes using the hot rolling method consists of three technological stages:
All technological processes The production of rolled pipes begins from the blank table. Here, workpieces of the required length are obtained from round solid rods, breaking them into hydraulic presses using pre-made cuts or cutting with shear presses without preheating.
After assembling a package of blanks, they are sent to a loading machine with a double-row loading. Heating temperature – 1150-1270℃, depending on the steel grade. After heating, the workpiece is sent along roller tables and racks to a centering machine, on which a recess is made at the end along its axis. After this, the workpiece is fed into the chute of the piercing mill.
Stitching mills come in disc, barrel and mushroom shapes. For piercing the workpiece, stands with barrel-shaped rolls rotating in one direction are most often used. The roll axes are located in vertical planes parallel to the axis of symmetry of the mill. Moreover, the roller axis makes an angle ß (feed angle) with the piercing axis from 8 to 15 degrees, depending on the size of the sleeve.
The hole in the sleeve is formed by a mandrel, which is fixed on a long fixed rod. Their axes coincide with the axis of the firmware. The heated workpiece moves towards the rolls towards a mandrel installed in the zone of maximum roll diameters - pinch. Upon contact with the rollers, the workpiece begins to move in opposite direction, and due to the feed angle it receives translational motion, which ensures a helical trajectory of each point of the deformed metal. This results in a thick-walled sleeve.
The outer diameter of the sleeve is approximately equal to the diameter of the workpiece, but due to the formation of a hole, its length increases by 2.5-4 times compared to the original length of the workpiece.
The sleeve obtained on a piercing mill is rolled into a pipe of the required diameter and wall thickness different ways. The method of rolling the sleeve into a pipe characterizes the type of pipe rolling plant. In the conditions of PNTZ, this is rolling on automatic, continuous and three-roll rolling mills.
Units with an automatic mill received the most wide application. A wide range of rolled pipes with a diameter from 57 to 426 mm and a wall thickness from 4 to 40 mm, as well as easy adjustment to pipes of other sizes, provide greater maneuverability in operation on such a unit. These advantages are combined with fairly high performance.
Structurally, the automatic mill is a two-roll non-reversible stand, the rolls of which have grooves that form a round pass. Before inserting the liner into the rolls, a stationary short round mandrel on a long rod is installed in the gauge, so that the gap between the mandrel and the gauge determines the diameter of the pipe and the thickness of its wall. The metal is deformed between the rolls and the mandrel. In this case, along with the thinning of the wall, there is a decrease in the outer diameter of the pipe.
Since rolling in one pass does not ensure uniform deformation of the wall along its perimeter, it is necessary to give two, and sometimes three passes, each time with edging, i.e. with the pipe rotated 90 degrees around its axis before placing it into rolls.
After each pass, the rolled sleeve is transferred to the front side of the stand using a pair of friction return rollers mounted on the output side of the mill. They rotate in the direction opposite to the rotation of the rolls. After each rolling, the mandrel is removed manually or using mechanisms and installed again before the next task of the liner.
The sleeve from the piercing mill falls into the chute and is pushed into the rolls by a pusher. After the first pass, the workpiece is returned, turned around its axis by 90 degrees and again fed into the rolls by a pusher. After each pass the mandrel is changed.
On three-roll rolling mills it is possible to roll pipes with a diameter of 34 to 200 mm and a wall thickness of 8 to 40 mm. The main advantage of this rolling method is the possibility of obtaining thick-walled pipes with minimal variation in thickness compared to methods of rolling pipes in round gauges.
The sleeve is deformed into a pipe using three rollers and a movable long mandrel. The rolls are equidistant from each other and from the rolling axis. The roll axes are not parallel to each other and to the rolling axis. The angle of inclination of the roll axis to the rolling axis in the horizontal plane is called the rolling angle φ, usually equal to 7 degrees. And the angle of inclination of the vertical plane is called the feed angle ß and varies in the range of 4-10 degrees, depending on the size of the rolled pipes. The rolls rotate in one direction and, due to the misalignment of their axes relative to the rolling axes, create conditions for the screw movement of the sleeve together with the mandrel.
Once on the gripping cone of the rolls, the sleeve blank with the mandrel inside is compressed along the diameter and along the wall. Deformation along the wall is carried out mainly by the ridges of the rollers. On the rolling and calibrating cones, the wall thickness is leveled, ovalization is reduced and there is a slight increase in the internal diameter of the pipe blank. This creates a small gap between the walls of the future pipe and the mandrel, which makes it easier to remove the latter from the pipe upon completion of rolling.
As calibration equipment for thick-walled pipes, a three-roll mill is used, similar in design to a rolling mill, but less powerful, since the deformation along the diameter is small and the wall thickness remains unchanged.
For pipes of smaller diameter and with smaller wall thickness, a continuous sizing mill consisting of five stands is used.
The productivity of the unit with a three-roll rolling mill is up to 180 thousand tons of pipes per year. The advantages of these mills include the ability to produce pipes high precision, quick adjustment from size to size, good quality inner surface products.
The process of rolling out a sleeve in a continuous mill takes place in a number of successively located twin-roll stands. Rolling is carried out on a long movable cylindrical mandrel in stands with rolls having round gauges.
Just like on an automatic mill, the cross-section of the pipe is determined by the annular gap between the roll grooves and the mandrel. The difference is that the long mandrel moves along with the rolled pipe.
As it passes through the cages, the number of which can reach nine, the liner is reduced: it decreases in outer diameter and is compressed along the wall. Since deformation in round gauges occurs unevenly, the pipe after the stand has an oval shape, it must be set with the larger axis of the oval along the height of the gauge, i.e. having previously rotated 90 degrees around the axis. To do this, change the direction of deformation of the rolls. To do this, each subsequent cage is rotated relative to the previous one at a right angle, and the cages themselves are located at an angle of 45 degrees to the horizon. This makes it possible to increase the compression in the cages and increase the compression of the pipes.
The continuous mill is designed for a high elongation factor - up to 6, so the pipe length can reach 150 meters. The continuous mill produces pipes with a diameter of 28 to 108 mm, a wall thickness of 3 to 8 mm and a length of more than 30 meters. High rolling speed (up to 5.5 m/sec) ensures high productivity (up to 600 thousand tons of pipes per year).
The final technological operation for all pipe rolling methods is the operation of cooling the products on cooling tables. To eliminate longitudinal curvature, cooled pipes are straightened on straightening mills. Special calibrated mill rolls carry out helical movement of the pipe, thereby eliminating existing axial distortions. Pipe ends are trimmed on lathes. If necessary, chamfers are removed.
In conclusion finished goods subject to quality control. After inspection, suitable pipes are packaged using a knitting machine and then sent to the finished product warehouse.
Hot-rolled solid steel pipes are widely used in the construction of pipelines of all diameters; they are used for the production of metal structure parts, machine and mechanism elements, columns, trusses and beams, foundation piles, lighting poles, in housing and communal services and road construction.
From technical characteristics hot-rolled pipe according to GOST, the scope of its application also follows. These are highly critical pipelines that require extreme strength, virtually eliminating the possibility of leaks:
In the catalog warehouse complex "ChTPZ" presents a wide range of hot-deformed seamless steel pipes in accordance with GOST 8732-78 for the needs of the oil and gas industry, chemical industry, construction, municipal and agriculture. You can place an order on the website or by phone . Compliance with the requirements of the state standard guarantees high technical and operational characteristics and a long service life of the pipe products sold. All products come with quality certificates.
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 the blanks is as close as possible to the configuration of the finishing products. Allowance for machining are no more than 5mm. Current modern technology allows you to produce forgings that have a variety of configurations and have a structure and properties that ensure their use under the most severe loading conditions, increasing the service characteristics of products in terms of fatigue strength from 1.5 to 6 times. Metal savings are ensured, manufacturing labor intensity is reduced, quality and operational reliability are increased products. Blanks after rolling stamping fully meet the term “precision blank parts”.
Induction heating METHOD OF END ROLLING FORGINGS by the method of end rolling of a “body of rotation”
The product manufacturing process itself undergoes multi-stage research preparation. To assess the quality of the material, preliminary tests are carried out. During the study terms of reference it is taken into account where this product will be used, what technological treatments it will undergo. Drawings and design documentation undergo a series of control approvals with the customer and only after that prototypes are produced. Reach High Quality products in mass production, when the order volume can reach up to 2,000 -3,000 pieces of forgings, is impossible without careful preparation of production and well-developed technology. Our approach to mastering each new product is exclusively professional.
The products of Gefest-Mash LLC are manufactured under controlled conditions established by the Quality Management Certification System, which meets the requirements of GOST ISO 9001-2011 (ISO 9001:2008), registration number ROSS RU. 0001.13IF22.
Currently mastered the following types forgings
Bushing Piston core Valve plate Trunnion
Pump bushing for 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 Art. 40Х Plate Art. 20ХГНМ Speed gear Art. 40Х Flange made of Art. 12Х18Н10Т Electric generator drive crown hub Railway train Art. 45
Gas pipeline flange (РH16-160) Art. 40X, 09G2S, 20 BRS connection Art. 45 Hollow shaft (Bushing) Railway art. 45 Valve plate Art. 40khn2ma Pump piston core Art. 40X
Axial fan flange Piston core 2 Fan hub st. Washers for gas pipelines st. 40X Fan hub of railway rolling stock locomotive
Bending on GGM used for the manufacture of forgings that require a significant stamping space and a large slide stroke. In order for bending to end at the lower limit of stamping temperatures (800-850°C), the workpieces are heated to 900-1000°C (more high temperatures heating is undesirable, since deviations in forging dimensions from the specified ones increase at bending points). A long workpiece is not heated along its entire length, but only the areas located in the bending zone and adjacent to this zone. Bending in dies is completed by straightening and sometimes calibration.
Rolling performed on forging rollers to shape blanks for subsequent stamping on other stamping units. During the rolling process, the cross-section of the workpiece decreases (but it should not be less than the maximum cross section product), and its length increases; in this case, a product with different sections along the length is obtained.
Depending on the complexity of the shape, rolling can be single- or multi-transition. Accordingly, the rolls can have single- or multi-strand inserts installed in single-stand rolls. Stamping in them can be performed without turning or with turning by 90° after each transition. In multi-cage rollers, rolling is performed without turning over the pass. Thus, at the Volzhsky Automobile Plant, the preparation of semi-axle blanks, preheated in an inductor, before stamping on a gas-filling machine, is carried out on nine-stand rollers operating in automatic mode. Rolling is also successfully used for stamping forgings from a rod with the formation of a flash. The forgings coming out of the rollers are connected to each other by a common flash. During subsequent trimming of the flash, the forgings are separated.
Rice. 7.6.
For hot rolling performed on ring-rolling machines (Fig. 7.6), ring-shaped workpieces are used. The workpiece 1 is rolled out between the pressure 4 and central 3 rolls. Roller 4 is driven and presses on the workpiece, due to which it acquires the required cross-sectional shape and diameter. Roller 5 is a guide, and roller 2 is a control roller. When the rolled forging comes into contact with roller 2, the latter begins to rotate, the pressure roller moves back to its original position and rolling ends. The cross-sectional shape of the wall of the rolled ring can be varied and is determined by the profile of the rolls.
Rice. 7.7.
Method hot rolling of teeth gears are made from a pre-processed workpiece, which is heated in an inductor to the required depth and to the required temperature. When making individual wheels (Fig. 7.7), the heated workpiece 2 is clamped on the mandrel with rings 3 and rotating rollers 1 and 4 with teeth are brought to it: as a result, the workpiece begins to rotate and teeth are formed on it. Rolls 1 and 4 are equipped with collars 5 at the ends, limiting the movement of metal along the tooth. Knurling performance at best quality gears is approximately 50 times higher than the productivity of rough gear cutting.
For high speed hot die forging in closed dies, high-speed hammers are used with a deformation speed of 18-20 m/s, at which the forces of contact friction are reduced, the contact time of the workpiece with the tool is reduced, as a result of which the heat released during the process of plastic deformation (thermal effect) is not dissipated, but remains in the workpiece and increases its temperature. These factors contribute to an increase in the ductility of the metal, as a result of which it is possible to process low-plasticity metals and alloys, such as tungsten, with high-speed hammers: fast-cutting steels, titanium alloys, etc.
Rice. 7.8. Scheme of isothermal stamping with stacking of blanks: a - before stamping, b - after stamping; 1, 4, 7, 10 - dies, 2, 5, 8, 11 - blanks, 3, 6, 9, 12 - punches, 13 - press slide, 14 - container, 15 - heater, 16 - heat-insulating material, 17 - casing
Isothermal stamping(Fig. 7.8) is performed at an almost constant temperature of special steels and alloys that have a narrow processing temperature range (for example, 30-50 ° C for some heat-resistant alloys). The stamp for such stamping is made of heat-resistant materials and installed in induction heater or a resistance heater that ensures the same temperature of the workpiece and die inserts.
Under isothermal conditions, it becomes possible to use the “superplasticity” effect, i.e. the ability of some metals and alloys to sharp decline resistance to deformation and increased ductility with decreasing strain rate.
The introduction of the method into the engineering industry and, in particular, into forging and stamping production has great prospects. cross-wedge rolling of step billetsØ 10-250 mm and length up to 2500 mm, intended for subsequent hot die forging, for example, forgings of a connecting rod of an automobile engine, in which there is no need for preparation transitions.
For rolling, rods made of carbon and tool steels, as well as a number of heat-resistant and non-ferrous alloys are used. Cross-wedge rolling lends itself well to full automation, increases labor productivity by 5-10 times compared to forging and turning on automatic lathes, reduces metal consumption by 20-30% and reduces the cost of products.
Rice. 7.9. Cross wedge rolling schemes using roller (a), flat (b) and roller-segment (c) tools
In the process of cross-wedge rolling, a round billet, the diameter of which is equal to or greater than the maximum diameter of the product, is deformed with a reduction degree of 1.1-3 by two rolls or plates with wedge elements on the surface (Fig. 7.9).
During the rolling process on two-roll mills, the workpiece is held in the deformation zone using guide bars located along the inter-roll space or bushings located at the ends of the rolls. Machines with flat tools instead of rotating rollers have flat slabs with protruding wedges. On roller-segment mills, the shape of workpieces is carried out by moving a convex and concave wedge tool towards each other. The convex tool is mounted on a rotating roll, the concave tool is mounted on a stationary segment.
UDC 621.73
FINITE ELEMENT MODEL FOR CALCULATING THE AMOUNT OF ACCUMULATED STRAIN DURING HOT ROLLING OF RINGS
© 2009 F.V. Grechnikov1, E.V. Aryshensky1, E.D. Beglov2
1 Samara State Aerospace University 2 JSC "Samara Metallurgical Plant"
Received by the editor 02/13/2009
A finite element model has been developed for calculating the degree of accumulated deformation at various stages of deformation of a ring workpiece. A comparison of modeling results and experimental dependencies confirms the adequacy of the model.
Key words: rolling of rings, macrostructure, recrystallization, accumulated deformation, finite element method, model, stiffness matrix, equal-strength inserts.
In the practice of gas turbine engine production, ring parts with multifunctional purpose. These details are subject to high requirements by structure and level of mechanical properties. The main method for producing ring parts is hot rolling (Fig. 1). A feature of this process is the presence of multiple acts of local deformation of the workpiece while it is in the rolls and the accompanying multiple partial recrystallization in interdeformation pauses, making it difficult to calculate the total (accumulated) deformation during the process.
This leads to the fact that along the cross-section of the workpiece, various degrees of deformation, including critical degrees of deformation, can simultaneously be present. In turn, critical degrees of deformation contribute to the formation of large grains during final recrystallization annealing. At the same time, in places where the deformation has exceeded critical values, a fine-grained structure will form. Thus, heterogeneity of deformation leads to heterogeneity of grain, i.e. structural heterogeneity over the cross-section of parts and a decrease in the level of mechanical properties. To avoid this, it is necessary to know at each stage the amount of accumulated deformation received by the metal both at each local stage of deformation and for the entire rolling period as a whole. In this regard, the purpose of this article is to build mathematical model, allowing you to determine the stress
Grechnikov Fedor Vasilievich, Doctor of Technical Sciences, Professor, Corresponding Member of the Russian Academy of Sciences, Vice-Rector for Academic Affairs. Email: [email protected]. Aryshensky Evgeniy Vladimirovich, graduate student. Email: [email protected].
Beglov Erkin Dzhavdatovich, candidate of technical sciences, leading engineer. Email: [email protected].
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 around the circumference. Taking this circumstance into account, 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 using the following formula.
12 1 ■ Kg
(2YAN + 2YAV), (1)
where YAN, YAB are the outer and inner radii of the ring;
K is the average radius of the ring in 1 revolution.
b is the length of the arc of contact with any of the rolls. To determine it, the formula is used
b 1(2) AN, (2)
Rice. 1. Process diagram hot rolling 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 drive and non-drive rolls
A b - absolute compression We first divide the solution area into quadrangular sectors, each of which corresponds to two adjacent 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 axes 1 and 2 as xc, X"2
World Cup)] NMMM)| ;<3>
1 Evn.+Dn-Dn then!± ^toD
During the calculation process, the coordinates of nodes at any point in the calculation area will change by
relocation of nodes ip, 2. To find ip, 2 we will use the energy method. Consider a separate triangular element 1 with nodes 1, 2, 3 in Fig. 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
tion of nodes will have a displacement d11, d12, d, d22, d^, d32. The superscript refers to the element, we will omit it in the future. 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 initial one, it is the difference between the energy of the stressed state accumulated in the element u and the work done by the forces /2,/3 on the displacement vector e, .
I=u-Zh=2 |(p + st22£22+^^ Uj-A 1j11 -
Fig 3. Setting boundary conditions in the problem of segment deformation
where е12.....- movements at the nodes of the element
in directions 1,2 respectively;
/p...... /32 - forces under the influence of which
the nodes shift in the direction of 1,2, respectively;
е11 е22 are normal, and е12 are tangential components of the deformation tensor;
y11y22 - normal, y12 - tangential components of the stress tensor.
Integration is carried out over volume ^ (in the case under consideration plane strain - by area element dF). For the convenience of further solution, we present equation (5) in matrix form.
I = - |a -e-eG-e 2
Г = 2\еТШЧеГ - =
Values of the vector components е = |е„ ■■■ е32|| must be such that the potential energy I has a minimum value:
■- = 0 ; Н1...3, . (7)
After differentiation, in vector form we get:
I -ING)-ё = f. (8)
To understand the notation, ||in||, and ||and|| Let's look again 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 relate the displacement values of the element nodes and its deformation with the following formula.
X22 X-32 X11 X31 X32 X12 X21 X11
21 Hz 12 22
In matrix form, we write expression (9) 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 movement 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. Conclusion ||AND|| for both conditions
can be found in . Its values are given here, and only for the plane strain and the energy approach. Elastic deformation:
1 + V 1- - 2v 1 - 2v
Plastic condition:
)- ее = |И| - 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 allows us to take into account the dependence of stress on deformation and other process parameters, which are expressed through a relationship of the form
0 = 0(e, e, T, a in c), (17)
where e is the accumulated strain under uniaxial compression (tension);
e - deformation rate; T - temperature;
aoa a, b, c - empirically determined relationships. Dedicated to the search for such relationships
But a large number of research. We used the results for alloys used in rolling gas turbine engine rings.
Let's 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. Having excluded displacements from formula (8), we denote its left side as follows.
Ш = М-|И-B-dF- (18)
Sh 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 right-hand side matrix 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 gripping 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 - friction coefficient.
Let's consider equation (19), which in expanded form for node 9 will be written as follows (Fig. 3,b).
k17.17 d91 + k17.18 d92 + 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 +
K18,21 d111 + k18,22d112 = f92 =
P sin (p3 + /uP cos (p3. (21)
When solving equations (20) using the Gaussian method, we take into account the condition of non-penetration of the workpiece material into the non-driven roll:
d91 ■ sin (р3 = d92 ■ cos^3. (22)
This condition will allow us to exclude d92 from the system of equations (19). We carry out this transformation for all equations containing nodes lying on the surface of the non-driven roll.
The rotation speed of the drive roll is known, but the mutual displacement of the metal and roll surfaces is unknown. Let's apply the following technique.
Let's introduce a fictitious layer of elements. Let's show it using the example of an element with nodes 7, 6 (Figure 3a). These units move as if rigidly connected to the roll. The nodes of the metal contact layer 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 more rigid, simulating low friction. When m ^ 1, the “sticking” of the material to the rolls is simulated. The elements do not model the lubricant layer, but they model the action of the lubricant. Each element of the fictitious layer is created at the time of construction of the corresponding real element. The real and fictitious element matrices can be compared and jointly solved in equation (8). The movements of the fictitious units are known, i.e. they move as if 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 + k10,11 d61 + k10,12d62 = f52 . (24)
Since the force in node 5 is normal to the surface of the roll, we have:
f2Cos^2 = fs1sin (P2, (25)
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. 4. Layout of equal-strength inserts in the deformation zone during rolling. H0 is the thickness of the workpiece before it enters the rolls; y, x - values of insertion coordinates;
a0, b0 and ax, bx
initial and final dimensions of the inserts, respectively
52, db1, 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 accumulated deformation, 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 ring rolling given in the work. In this work, we investigated the deformation zone of a ring made of aluminum alloy AMg6, in which
Holes were drilled in layers and filled with inserts made of the same metal (Fig. 4). 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 the diameters of the work rolls: upper drive - 550 mm and lower non-drive - 200 mm; the maximum feed speed of the pressure device was 16 mm/sec.; the rolling speed provided for by the mill design was 1.5 m/sec. Based on the results of measuring the inserts, the values were found
"h T| /) / [>
___^ S.GChS1 IG I /1^1111.1S
¿■¡i nt I a
V №|en.nch I data
5vep;rsks t;
anspsro-."and that
SgU 1, and inm b?
S:ch:"ini 2 ^ I member MZDSL.-fEBaMN!
■I l -I l i i e. 2 t.i 11 i. 7VDSH1 V ■DIM [-1
Rice. Fig. 5. Distribution of the intensity of deformation along the height of the deformation zone when rolling out a ring sample from the AMg6 alloy: e1 is the degree of accumulated deformation, y is the coordinates of the point along the y axis (with Ho /2 corresponding to the ordinate 1)
deformations and stresses, which are presented in Fig. 5. The presented experimental data on rolling out a ring made of AMg6 alloy were introduced into the developed finite element model. In Fig. Figure 5 compares the 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 a gas turbine engine, it is necessary to control the magnitude of the accumulated degree of deformation at each stage of hot rolling of the workpiece.
2. A finite element design model has been developed.
the degree of accumulated deformation at various stages of deformation of ring blanks.
3. A comparison of modeling results and experimental dependencies confirms the adequacy of the model.
BIBLIOGRAPHY
1. Lakhtin Yu.M., Leontyeva V.P. Metallurgy. M.: Mechanical Engineering, 1980. 493 p.
3. Tselikov A.I. Theory of force calculation in rolling mills. - M.: Metallugrgizdat, 1962.
2. Finite-element plasticity and metalforming analysis / G.W. Rove., C.E.N. Sturgess, P. Hartly., Cambridge University Press, 2005. 296 p.
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. Rolling out rings. -Samara: SSAU, 2000. P. 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 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]
Unified Tariff and Qualification Directory of Works and Professions of Workers (UTKS), 2019
Part No. 1 of Issue No. 2 of ETKS
The issue was approved by Resolution of the Ministry of Labor of the Russian Federation dated November 15, 1999 N 45
(as amended by Order of the Ministry of Health and Social Development of the Russian Federation dated November 13, 2008 N 645)
Characteristics of work. Hot rolling of ring blanks 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 adjustments.
Must know: device and methods for adjusting serviced rolling machines and electric heating devices; steel grades used for ball bearing rings; purpose and conditions of use of control and measuring instruments.
Characteristics of work. Hot rolling of ring blanks for bearings with a diameter of over 250 to 350 mm on rolling machines and blanks into a conical disk for car wheels on a disc rolling mill. Setting up the mill. Hot rolling of ring blanks for bearings with a diameter of over 350 mm on rolling machines together with a more highly qualified roller.
Must know: device of the disc rolling mill and kinematic diagrams of serviced rolling machines; steel grades used for rolling blanks of machine wheel disks; temperature and heating mode of workpieces; device of control and measuring instruments.
Characteristics of work. Hot rolling of blanks of bearing rings with a diameter of over 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. Attachment of rolling machines to rings.
Must know: kinematic diagrams of various rolling machines, disc rolling mill and heating devices used for rolling rings and spherical shells; optimal heating modes for workpieces; allowances and tolerances during processing; dependence of the degree of radial compression on the thickness at various points of the workpiece; methods for setting up sheeting machines.
Characteristics of work. 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 over 1500 mm on rolling machines. Rolling of thin-walled parts made of corrosion-resistant steels and molybdenum alloys.
Must know: technological process of rolling out large-sized and thin-walled parts; design of kinematic, hydraulic and heating devices and methods for their adjustment; ways to achieve the established processing accuracy; rules for calculating parabolic shells associated with performing various works.
