RU2254383C1 - Meth0d of heat and-power-treatment of long-cut articles - Google Patents

Abstract

FIELD: heat-and-power treatment of long-cut low-rigid axisymmetrical parts, such as shafts.

SUBSTANCE: proposed method includes power action on blank in the course of complete cycle of heat treatment; heat treatment cycle is divided into three sub-cycles; each sub-cycle includes action on blank within selected area by successive deformation in various directions; boundaries of selected area are controlled by control of temperature action on blank; length of section is selected taking into account harmonics of vibrations of part. In the course of complete cycle of heat treatment, sections at insufficient deformation are heated and those at excessive deformation are cooled. Device proposed for realization of this method includes jig with blank retainer and heating element which is provided with hole for placing the blank; each retainer is provided with wedges engageable with rods fitted with hydraulic cylinders at their ends, guide ring mounted for free rotation in retainer hole and pneumatic system; ring-shaped heating element is arranged coaxially relative to blank. Each section has four prods and is insulated by means of heat-insulating inserts located inside heat-insulating rings in form of corrugated bushes. Heating element is of induction type. This device includes control system equipped with linear motion and angular position sensors fitted in retainers and connected with control circuit; control system has three control circuits: one circuit is used for control of level and rate of longitudinal deformation; second circuit is used for control of level and rate of torsional deformation and third circuit is used for control of temperature action; each control circuit includes sensor, amplifier, adder, parameter setter and control unit.

EFFECT: enhanced stability of sizes and shape of long-cut articles due to elimination of directivity of axial residual deformation and directed texture of material lengthwise.

9 cl, 9 dwg

Description

The present invention relates to the field of thermal power treatment (TCO) of long axisymmetric parts such as a shaft and can be used in technological processes of manufacturing shafts in machining workshops.

A known method of thermal power treatment of shafts, including heating, torsion, surface plastic deformation and cooling, carried out continuously-sequentially along the length of the shaft [1].

The disadvantage of this method is the uneven deformation along the length of the shaft due to the heterogeneity of the physico-mechanical properties of its material, the use of large deformation forces.

A known method of processing axisymmetric parts, including the deformation of the workpiece by compression or compression with torsion by means of pins while heating the workpieces [2].

The disadvantage of this method is the limited scope (machined parts such as a disk with shaping, occurring mainly due to the rolling operation), large deformation forces and uneven deformation along the length of the workpiece.

The closest method to the claimed invention, selected as a prototype, is a method of manufacturing axisymmetric parts, including static and / or dynamic power, and / or other effects on the initial isotropic structure of the material of the product with the translation of this structure into an anisotropic prestressed structure during heat treatment [ 3].

The disadvantage of this method is the unevenness of the parameters of the deformation of the product due to the heterogeneity of the physico-mechanical properties of the material along the length and cross sections of the workpiece, as well as the lack of stability of the processing parameters.

The closest device of the same purpose to the claimed invention, selected as a prototype, is a device for TCO shafts of low rigidity, containing the slipway with grippers in end sections, and the slipway is made in the form of a pipe made of metal with a thermal expansion coefficient less than that of the product [4 ].

The disadvantage of this device is the inability to ensure the stability of the applied force during the TCO process, which can lead to material hardening, uneven along the length of the workpiece, the residual deformation of the metal and, consequently, to instability in the operational period, loss of accuracy.

The problem to which the claimed inventions are directed is to improve the quality of the workpieces with the following technical results: increase the stability of the size and shape of long lengthy rigid axisymmetric parts by eliminating the directivity of axial residual stresses and directional texture of the workpiece material along its length remaining after the procurement operation; reduction of the deformation force due to the use of the Bausinger effect; the destruction of technological heredity due to the complete restructuring of the material texture during compression and torsion of the workpiece due to the formation of a finely dispersed multidirectional texture in the material of the workpiece, which leads to a more uniform distribution of axial residual stresses along the length of the part, since during relaxation, axial residual stresses have the main effect on warping; this nature of their distribution leads to a decrease in the deformation of the part during the operational period.

This problem is solved by the fact that in the method of thermal power treatment of axisymmetric parts, including static force acting on the workpiece during the full heat treatment cycle, the processing cycle is divided into subcycles, during each of which the static force action is performed within the selected part of the workpiece first by sequential twisting in one direction of this section with subsequent stretching, then - twisting in the other direction with subsequent compression beyond the limit of the law of elasticity spine, wherein the control limit stress at the static force action produced by controlling the temperature influence on the blank portion and the portion length selected in accordance with the harmonic oscillations of parts. During the full heat treatment cycle, it is possible to establish the location of areas with deviations from a given strain value, to determine these deviations, while in areas with insufficient deformation they heat up, and in areas with excessive deformation they cool.

This problem is also solved by the fact that in the device for thermal processing of axisymmetric parts, containing the slipway with the clamps of the workpiece and the heating element, each of the clamps is made with a hole for placing the workpiece in it and contains wedges made with the possibility of diametrical compression of the workpiece and contact with rods, equipped at their ends with hydraulic cylinders, a guide ring mounted with the possibility of free rotation in the hole of the latch, and the ring is equipped with anti-friction inserts for e th preload from the ends, the air supply system, and the heating element is divided into sections by heat-insulating rings. The heating element can be made annular and placed coaxially relative to the workpiece. Each section can have four probes and can be insulated with heat insulating inserts located inside the heat insulating rings in the form of corrugated bushings. The heating element may be made inductive. The device for TCO may include a control system that is equipped with linear displacement and angular position sensors installed in the latches and included in the control circuit, while the control system may contain three control loops, one of which is configured to control the magnitude and speed of longitudinal deformation, the other - the magnitude and speed of torsional deformation, and the third - temperature exposure, and each control circuit contains a sensor, amplifier, adder, control value adjuster parameter and control unit.

The division of the processing cycle into subcycles expands the technological capabilities of the method by varying the processing sections, the integrated study of the material with the formation of a directional texture.

Static force action within the sections reduces the dimensions of the installation, makes it more compact, strengthens the workpiece in the sections, taking into account loading zones or harmonics of vibrations during operation of the part in the assembly, and forms a structure more uniform in length.

Torsion is necessary to create a more uniform picture of the distribution of residual stresses by forming a uniform texture along the length of the material, as well as creating a preliminary stress state.

Stretching the preform in the first stage is necessary to initiate plastic processes in the metal (formation and movement of dislocations, displacement and rotation of grains).

The compressive force is necessary to form a uniform pattern of the distribution of residual stresses with the least probability of destruction of the workpiece material as a result of plastic processes by creating the most favorable stress state scheme - volume compression.

Deformation beyond the limits of the law of elasticity leads to hardening of the material with the formation of a directional texture.

A machining cycle consisting of torsion in one direction, then in the other, with alternating stretching and compression, is necessary to reduce the deformation forces due to the Bausinger effect.

Heating of the deformable section of the workpiece is necessary to reduce the deformation forces by reducing the yield strength of the material of the workpiece at elevated temperature.

The control of the yield strength allows stabilizing the deformation in sections by regulating the deformation process in real time and in the required section of the section.

Temperature exposure control is an effective, simple and reliable means of controlling the yield strength of a material.

The choice of the length of the treated section, taking into account the harmonics of the oscillations of the part, reduces the degree of warpage of the part in the operational period due to the hardening of the material in accordance with the zones of loading the part.

Establishing the location of sections with a deviation from a given strain value is necessary for real-time alignment of the strain across sections.

The determination of the deviation of the strain is necessary to set the temperature regime of the impact on the sections in order to equalize the strain.

Heating sections with insufficient deformation increases deformation by reducing the yield strength.

Cooling of areas with excessive deformation slows down the deformation by increasing the yield strength.

Workpiece clamps with a hole allow you to process workpieces of various lengths evenly over the entire length due to its free passage through the hole.

Wedges with the possibility of diametrical compression of the workpiece and contact with the rod simplify the layout of the device by using a drive to create torques without articulated devices.

Hydraulic cylinders at the ends of the rods expand technological capabilities due to the smooth adjustment of the applied pressure and, accordingly, the deformation forces for various workpieces and processing modes.

The guide ring transfers a complex effect on the workpiece while maintaining the possibility of its rotation when significant axial loads are applied.

Rotating guide ring allows you to create angular displacements of the workpiece by applying torque.

Antifriction inserts for tightening the guide ring from the ends reduce working forces by reducing the coefficient of friction.

The air supply system controls the yield strength of the material due to the controlled heat removal from the workpiece.

The heating element, divided into sections, allows you to intensify the heat sink and heat supply over sections of sections and stabilize the deformation.

The ring-shaped heating element allows you to heat the workpieces of bodies of revolution around the perimeter.

A heating element placed coaxially with the workpiece allows it to be heated evenly around the perimeter.

The probes allow you to measure neck narrowing and control the deformation process in real time.

Four probes measure the change in the diameter of the necks taking into account their spatial deviations.

The insulating inserts seal the shaft sections, which allows cooling - heating the workpiece in sections and forming more uniform physical and mechanical properties along the length due to the exclusion of heat fluxes into neighboring sections.

Thermal insulating rings in the form of corrugated bushings allow you to adapt to different diameters of the workpieces, which makes this device more versatile.

The heat-insulating inserts inside the rings allow directing air flows separately to neighboring sections and, accordingly, cooling them at different speeds.

Inductive heating element increases the processing efficiency due to the simpler installation design, simplifies its operation while maintaining the quality of the surface layer.

The control system improves the processing efficiency due to the operational change of technological parameters as a function of the deformation process.

The linear displacement and angular position sensors determine the deformation in the axial and tangential directions in real time.

Control loops set and implement the necessary values of axial and torsional deformation, strain rate and temperature effect, taking into account the characteristics of a particular deformation process.

The present invention is illustrated by the drawings, presented in figure 1, which shows a diagram of the selection of deformation sections, figure 2-5 - sub-cycles of the shaft processing, figure 6 is a General view of the device for implementing the method TCO, figure 7 is a section A- And in Fig.6, Fig.8 is a callout B in Fig.6, Fig.9 is a structural diagram of a TCO process control system.

The method is carried out in the following sequence. The blank of the shaft 1 is placed in the retainers (Fig. 1), a portion of the blank is selected, a static force is applied to this portion under conditions of its heating, first by successively twisting in one direction (Fig. 2), followed by stretching (Fig. 3), then by twisting in the other direction (figure 4), followed by compression (figure 5). In the process of static force, the yield strength is controlled by controlling the temperature effect on the workpiece area. Establish the location of areas with a deviation from a given strain value, determine these deviations and produce a controlled temperature effect on these areas: in areas with insufficient deformation, heat, and in areas with excessive deformation, cooling. Upon completion of the processing of this section of the workpiece produce a similar processing of other sections.

что соответствует достижению площадки текучести. После этого включают привод осевых перемещений до достижения стадии пластического течения в продольном направлении. После этого цикл деформирования повторяют с кручением в обратную сторону и осевым сжатием. На обоих стадиях контролируется изменение диаметров шеек по участкам вала. Для участков вала, где после начала пластического течения произошла максимальная деформация, выключают нагрев соответствующей секции нагревательного элемента и подают поток охлаждающего воздуха, что повышает предел текучести материала на данном участке вала. Выключая нагрев и охлаждая участки вала, достигшие величины деформации первого участка добиваются равномерной деформации по всему пролету заготовки. Неоднородность напряжений, обусловленная неоднородностью положения зерен (разориентировкой) и их формой, уменьшается при выравнивании и образовании текстуры деформации, что снижает общую внутреннюю энергию заготовки. Более равновесная структура способствует стабильности форм и размеров детали.At the first stage, after heating the workpiece to a predetermined temperature, a signal about torsional deformation is removed. Torsion occurs until the derivative is equal to zero

which corresponds to the achievement of the yield site. After that, the drive of axial displacements is switched on until the stage of plastic flow in the longitudinal direction is reached. After this, the deformation cycle is repeated with torsion in the opposite direction and axial compression. At both stages, the change in the diameters of the necks along the shaft sections is controlled. For sections of the shaft where maximum deformation occurred after the start of plastic flow, the heating of the corresponding section of the heating element is turned off and a flow of cooling air is supplied, which increases the yield point of the material in this section of the shaft. Turning off heating and cooling the shaft sections that have reached the strain of the first section achieve uniform deformation over the entire span of the workpiece. The inhomogeneity of stresses due to the heterogeneity of the position of the grains (misorientation) and their shape decreases when the strain is aligned and the texture is formed, which reduces the total internal energy of the workpiece. A more balanced structure contributes to the stability of the shapes and sizes of the part.

A device for TCO of long axisymmetric parts (Fig.6-9) includes a slipway 2, where the shaft blank 1 is placed in the retainers 3 with holes 4, into which the shaft 1 passes. It is compressed from the diametrically opposite sides by wedges 5, which are contacted along bevels 6 along bevels insert 7 with a rod 8, which has power cylinders at opposite ends 9. The wedges 5 are inserted along the sliding fit into the guide ring 10, which can freely rotate in the hole 4 of the retainer 3, and the ring 10 is pressed from the ends by antifriction inserts 12. Between the latches 3 in the frame 13 is installed a heating element 14, operating on the principle of inductive heating. At the ends of the slipway 1, hydraulic cylinders 15 are installed. 15. The linear displacement sensors 16 are placed in the clips 3, and the angular position sensors 17 are placed in the guide ring 10. The control system includes three circuits. The first linear displacement control circuit 18 includes a deformation amount control circuit, which includes a linear displacement sensor 16, an amplifier 19, an adder 20, an axial deformation magnitude adjuster 21, an axial deformation rate control circuit that includes an angular position sensor 17, an amplifier 22, differentiating link 23 and the linear strain rate adjuster 24. Similar two circuits are included in the torsional strain control loop 25. The temperature control loop includes a thermocouple 26, a tamper adjuster tours 27, temperature control unit 28. The power circuit 29 has pressure sensors 30 of the hydraulic cylinders 9 and 15. The heating element is made in the form of a coil 31, divided into sections 32 by heat insulating inserts 33, inside the hollow corrugated rings 34. The corrugated rings 34 have air supply openings 35 . Each probe contains four probes 36, the outputs of which are connected to the position sensor 37. Adders 20 are connected to a switch 38, which is connected to the power circuit 29, coil 31, air supply system 39 in section 32.

A device for TCO works as follows. The billet of the shaft 1 is pulled through the first latch 3 and the heating element to the second latch 3 and heated in the area between the latches 3 when an electric current is supplied to the coil circuit of the heating element 14. The heating temperature and holding time are determined based on the material of the workpiece 2 and the required depth of the plastic deformed layer . After heating the shaft section 1, the operating pressure is supplied to the hydraulic cylinders 9 of the clamps 3, while the rods 8 are moved, which, along the bevels 6, press on the wedges 4. On the guide ring, the wedges 4 are shifted to the workpiece of the shaft 1, clamping it. In this case, the hydraulic cylinders 9 create a torque relative to the axis of the workpiece 1. Torsion is carried out first in one direction at a certain angle, then, after stretching, in the other. Moving to a predetermined angle, the wedges 4 rotate the floating insert 7, thereby ensuring reliable contact over the entire surface of the bevel 6 of the wedge 5. After reaching a certain clamping force with the clamps 3, the working pressure is supplied to the side hydraulic cylinders 15. At the same time, the clamps 3 move along the stock 2 creating tensile or compressive strains. The section of the workpiece 1 between the clamps is subjected to complex deformation: torsion - compression (stretching) for a given processing cycle. All signals from the adders 20 enter the switch 38, where a control action is generated on the hydraulic cylinders 9, 15, coil 31, and the air supply system 39 to supply air to the respective sections 32.

Sources of information

1. RF patent №2161276, cl. F 16 F 1/14, 2000.

2. RF patent №2119842, cl. B 21 K 1/32, 1998.

3. Application of the Russian Federation No. 96112649, cl. B 21 K 1/28, 1998.

4. Copyright certificate of the USSR No. 1407969, cl. C 21 D 1/62, 1/63, 1988.

Claims (9)

1. The method of thermal power treatment of axisymmetric parts, including static force acting on the workpiece during the full heat treatment cycle, characterized in that the processing cycle is divided into sub-cycles, during each of which the static power action is performed within the selected part of the workpiece first by sequentially twisting into one side of this section with subsequent stretching, then twisting to the other side, followed by compression beyond the limit of the law of elasticity, and The pressure in the static yield stress of the impact force produced by adjusting the temperature influence on the blank portion and the portion length selected in accordance with the harmonic oscillations of parts. 2. The method according to claim 1, characterized in that during the full heat treatment cycle, the location of the sections with deviations from the given strain value is determined, these deviations are determined, while in the areas with insufficient deformation they are heated, and in the areas with excessive deformation they are cooled. 3. A device for thermoset machining axisymmetric parts, comprising a slipway with clamps of the workpiece and a heating element, characterized in that each of the clamps is made with an opening for placing the workpiece in it and contains wedges made with the possibility of diametric compression of the workpiece and contact with rods equipped with at its ends with hydraulic cylinders, a guide ring mounted with the possibility of free rotation in the hole of the latch, and the ring is equipped with anti-friction inserts for preloading ends, the air supply and the heating element is divided into sections of insulating rings. 4. The device according to claim 3, characterized in that the heating element is made annular and placed coaxially relative to the workpiece. 5. The device according to claim 3, characterized in that each section has four probes and is divided by insulating inserts located inside the insulating rings made in the form of corrugated bushings. 6. The device according to any one of paragraphs.3 and 4, characterized in that the heating element is made inductive. 7. The device according to claim 3, characterized in that the device further comprises a control system that is equipped with linear displacement and angular position sensors installed in the latches and included in the control circuit. 8. The device according to claim 7, characterized in that the control system contains three control loops, one of which is configured to control the magnitude and speed of longitudinal deformation, the other - the magnitude and speed of torsional deformation, and the third - by temperature. 9. The device according to any one of paragraphs.7 and 8, characterized in that each control circuit contains a sensor, amplifier, adder, setpoint value of the controlled parameter and the control unit.

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