Fastener thread rolling system and method

Abstract

The invention discloses a thread rolling system and method for a fastener, and the system comprises a mounting seat, a first thread rolling plate, a second thread rolling plate, a first driving mechanism for controlling the indirect pressure between the first thread rolling plate and the second thread rolling plate on a first axis, and a second driving mechanism for controlling the indirect pressure between the first thread rolling plate and the second thread rolling plate on a second axis, the second driving mechanism is used for driving the first thread rolling plate or the second thread rolling plate to move along the second axis, hydraulic oil of the first driving mechanism is provided by the second driving mechanism, and the pressure of the hydraulic oil in a cylinder body of the second driving mechanism rises rapidly; and feedback verification is carried out by a pressure sensor, so that delay caused by signal transmission of an axial driving mechanism and a radial driving mechanism in an original thread rolling device through a master controller is shortened, and machining parameters during thread rolling are quantitatively and uniformly controlled in advance through a tensile testing machine; and the aluminum alloy fastener subjected to thread rolling can have excellent appearance, size specification and mechanical property.

Description

Technical Field

[0001] This invention belongs to the field of fastener processing, and specifically relates to a fastener thread rolling system and method. Background Technology

[0002] The processing technology and equipment for steel fasteners are relatively mature. However, with the widespread use of lightweight materials, the galvanic corrosion problem between commonly used steel fasteners and aluminum components affects their widespread application. Currently, the thread processing solutions for aluminum fasteners generally directly adopt the processing technology of standard steel fasteners. Although they can be assembled as standard fasteners, the differences in material properties mean that the equipment and methods used to process steel fasteners cannot be well adapted to the thread rolling process of aluminum fasteners. This results in problems where different processing degrees affect the assembly effect of fasteners, especially with the high requirements for the timing and magnitude matching of the radial and axial forces during thread rolling. Existing equipment often collects signals for the radial and axial forces separately and feeds them back to the main controller, which then controls them uniformly. This results in delays and accuracy deviations in the coordinated action control of the first and second drive mechanisms. Summary of the Invention

[0003] The purpose of this invention is to provide a fastener thread rolling system in which a second drive mechanism directly controls a first drive mechanism, eliminating signal forwarding delay and improving the coordination between the first and second drive mechanisms to ensure thread rolling accuracy.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a fastener thread rolling system, comprising: The mounting base has a first axis parallel to its upper end face and a second axis perpendicular to its upper end face; The first and second tooth rolling plates are both mounted on the mounting base, and the first and second tooth rolling plates can slide relative to each other along the first axis and the second axis. A first drive mechanism is used to control the indirect pressure between the first and second tooth-rolling plates on the first axis. The second drive mechanism is used to drive the first or second tooth-rolling plate to move along the second axis. The first drive mechanism includes a first actuator and a first acquisition module for acquiring the working parameters of the first actuator; The second drive mechanism includes a second actuator, a second acquisition module for acquiring the working parameters of the second actuator, and a control module for controlling the action of the second actuator based on the parameters acquired by the second acquisition module. The first acquisition module is electrically connected to the control module, and the control module also controls the action of the first actuator based on the parameters acquired by the first acquisition module. The fastener to be threaded is installed between the first threading plate and the second threading plate. The first drive mechanism controls the distance between the second threading plate and the first threading plate on the first axis. The second drive mechanism causes the first threading plate and the second threading plate to slide relative to each other along the second axis to complete the threading.

[0005] In another embodiment, the tooth-rolling system further includes a first mounting plate slidably connected to the mounting base along a first axis and a first clamping plate slidably connected to the first mounting plate along a second axis. The first tooth-rolling plate is mounted on the first clamping plate, and the first mounting plate and the first clamping plate are slidably connected by dovetail grooves and dovetail sliders respectively provided on the two.

[0006] In another embodiment, a first groove extending along a second axis is formed on the first clamping plate, and a first locking bolt that can at least partially extend into the first groove is threaded onto its side wall. The first toothed plate is installed in the first clamping plate and is fixedly connected to the first clamping plate by the first locking bolt.

[0007] In another embodiment, the tooth-rolling system further includes a first positioning plate fixedly connected to the lower end of the first mounting plate and a first adjusting bolt. The first positioning plate is provided with a first oblong hole, and the first adjusting bolt passes through the first oblong hole and is threadedly connected to the mounting base. The position of the first mounting plate on the first axis of the mounting base can be adjusted by adjusting the tightness of the first adjusting bolt.

[0008] In another embodiment, the tooth-rolling system further includes a second mounting plate slidably connected to the mounting base along a first axis and a second clamping plate slidably connected to the second mounting plate along a second axis. The second clamping plate is located on the side of the second mounting plate facing the first mounting plate. The second tooth-rolling plate is mounted on the second clamping plate. The second mounting plate and the second clamping plate are slidably connected by dovetail grooves and dovetail sliders respectively provided on both.

[0009] In another embodiment, a second groove extending along a second axis is formed on the second clamping plate, and a second locking bolt that can at least partially extend into the second groove is threaded onto its side wall. The second toothed plate is installed in the second clamping plate and is fixedly connected to the second clamping plate by the second locking bolt.

[0010] In another embodiment, the second clamping plate is provided with a connecting plate. When the second drive mechanism is connected to the second tooth rolling plate, the second tooth rolling plate is connected to the second drive mechanism through the second clamping plate and the connecting plate. The connecting plate extends along the second axis and in a direction away from the mounting base, so that the second drive mechanism can be offset from the positions of the first mounting plate, the first clamping plate, the second mounting plate and the second clamping plate on the second axis, which facilitates the assembly of the second drive mechanism and the first clamping plate.

[0011] In another embodiment, the first drive mechanism is a hydraulic device, and the first acquisition module is a pressure sensor installed in the cylinder of the hydraulic device.

[0012] In another embodiment, the second drive mechanism is a tensile testing machine, and the thread rolling system further includes an oil supply pipe connected between the first drive mechanism and the second drive mechanism, wherein the hydraulic oil in the cylinder is supplied by the tensile testing machine.

[0013] The present invention also provides a thread rolling method based on the above-mentioned fastener thread rolling system, wherein the first thread rolling plate is fixed in relative position to the mounting base, the driving mechanism includes a base, a movable stage that moves relative to the base along a second axis, and a gripper disposed on the movable stage, the second thread rolling plate is connected to the gripper of the second driving mechanism, and the thread rolling method includes: a. Fix the mounting base to the base, and fix the second toothed plate to the clamp; b. Start the second drive mechanism and set the initial speed to make the gripper and the second tooth-rolling plate move upward simultaneously to perform tooth rolling; c. During tooth rolling, the pressure value P applied by the first drive mechanism to the second tooth rolling plate. R (i.e., the radial force of the tooth rolling) reaches its maximum value within time t, P R The value is obtained by calculating using the following formula:

[0014] Where: t≤1s; P R - Thread rolling radial force, N; L - Thread rolling length, mm; R P0.2 -Specified non-proportional elongation strength, MPa; P - Pitch, mm; d0 - Bolt blank diameter, mm; K1 - Empirical coefficient; When P R When the maximum value is reached, adjust the tensile force P of the tensile testing machine according to the following relationship. T The magnitude of (i.e., the axial force of the thread rolling):

[0015] Where: P T- Axial force of thread rolling, N; K2 - Empirical coefficient; During the bolt threading process, the radial and lateral forces must satisfy the above relationship until the threading is completed. After the threading is completed, the bolt is removed.

[0016] The beneficial effects of this invention are as follows: 1. This device uses a tensile testing machine to drive a second thread-rolling plate, causing relative movement between the second and first thread-rolling plates to form threads on the fastener to be threaded. During thread rolling, the load on the fastener is precisely controlled by the tensile testing machine and the hydraulic device. In particular, the hydraulic oil of the hydraulic device is supplied by the tensile testing mechanism. The pressure rise of the hydraulic oil in the cylinder of the hydraulic device is not only rapid, but also shortens the delay caused by the transmission of signals between the axial drive mechanism and the radial drive mechanism through the main controller in the original thread rolling device, because the required pressure value is transmitted to the hydraulic device in advance by the tensile testing machine and then verified by the pressure sensor. By pre-quantitatively and uniformly controlling the processing parameters during thread rolling by the tensile testing machine, the aluminum alloy fasteners after thread rolling can have excellent appearance, dimensional specifications and mechanical properties.

[0017] 2. By replacing different specifications and models of thread rolling dies and adjusting the spacing between the dies through a hydraulic mechanism, various thread specifications can be processed.

[0018] 3. During fastener thread rolling testing, the screw stroke can be flexibly adjusted according to the thread rolling quality, eliminating the need to redesign and process the thread rolling plate, thus saving time and manufacturing costs.

[0019] 4. Compatible with common thread rolling dies and fastener specifications on the market, and adaptable to various models of universal tensile testing machines on the market, with a wide range of compatibility; 5. The tooling size is significantly smaller than that of traditional thread rolling machines, reducing the footprint of the equipment. Attached Figure Description

[0020] Figure 1 This is a perspective view of the present invention; Figure 2 This is a perspective view of the invention after the tensile testing machine has been removed. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings: like Figure 1-2As shown, the fastener thread rolling system includes: a mounting base 1, a first thread rolling plate 2, a second thread rolling plate 3, a first mounting plate 4, a first clamping plate 5, a first locking bolt 6, a first positioning plate 7, a first adjusting bolt 8, a second mounting plate 9, a second clamping plate 10, a second locking bolt 11, a first drive mechanism 12, and a second drive mechanism 13. The first drive mechanism 12 controls the indirect pressure between the first thread rolling plate 2 and the second thread rolling plate 3 on the first axis. The indirect pressure refers to the pressure transmitted between the first thread rolling plate 2 and the second thread rolling plate 3 through the fastener 0 to be threaded. In this application, the first drive mechanism 12 is a hydraulic device, and the first acquisition module is a pressure sensor installed in the cylinder 20 of the hydraulic device. The second drive mechanism 13 is a tensile testing machine. The thread rolling system also includes an oil supply pipe 15 connected between the first drive mechanism 12 and the second drive mechanism 13. The first actuator can also be an electric cylinder or a linear motor, etc. When the first actuator is not a hydraulic device, the oil supply pipe 15 between the tensile testing machine and the hydraulic device can be omitted, and the hydraulic oil in the cylinder is supplied by the tensile testing machine. The second drive mechanism 13 is used to drive the first toothed plate 2 or the second toothed plate 3 to move along the second axis. In this application, the second drive mechanism 13 drives the second toothed plate 3 to move. The tensile testing machine is an electronic universal testing machine produced by Lisheng (Shanghai) Scientific Instruments Co., Ltd., and its model is LE5105.

[0022] Mounting base 1 has a first axis parallel to its upper end face and a second axis perpendicular to its upper end face; a first thread rolling plate 2 and a second thread rolling plate 3 are both mounted on mounting base 1, and the first thread rolling plate 2 and the second thread rolling plate 3 can slide relative to each other along the first axis and the second axis; specifically, a first mounting plate 4 is slidably connected to mounting base 1 along the first axis, a first clamping plate 5 is slidably connected to the first mounting plate 1 along the second axis, the first thread rolling plate 2 is mounted on the first clamping plate 5, and the first mounting plate 4 and the first clamping plate 5 are slidably connected by dovetail grooves and dovetail sliders respectively provided on them. A first groove 17 extending along the second axis is formed on the clamping plate 5, and a first locking bolt 6 that can at least partially extend into the first groove 17 is threaded on its side wall. The first toothed plate 2 is installed in the first clamping plate 5 and is fixedly connected to the first clamping plate 5 by the first locking bolt 6. The first positioning plate 7 is fixedly connected to the lower end of the first mounting plate 4. The first positioning plate 7 is provided with a first waist-shaped hole. The first adjusting bolt 8 passes through the first waist-shaped hole and is threadedly connected to the mounting base 1. The position of the first mounting plate 4 on the first axis of the mounting base 1 can be adjusted by adjusting the tightness of the first adjusting bolt 8.

[0023] The first drive mechanism 12 includes a first actuator and a first acquisition module for acquiring the working parameters of the first actuator; the second drive mechanism 13 includes a second actuator, a second acquisition module for acquiring the working parameters of the second actuator, and a control module for controlling the action of the second actuator based on the parameters acquired by the second acquisition module. The first acquisition module is electrically connected to the control module, and the control module also controls the action of the first actuator based on the parameters acquired by the first acquisition module. The fastener to be threaded is installed between the first threading plate 2 and the second threading plate 3. The first drive mechanism 12 controls the distance between the second threading plate 3 and the first threading plate 2 on the first axis, and the second drive mechanism 13 causes the first threading plate 2 and the second threading plate 3 to slide relative to each other along the second axis to complete the threading.

[0024] The second mounting plate 9 is slidably connected to the mounting base 1 along the first axis, and the second clamping plate 10 is slidably connected to the second mounting plate 9 along the second axis. The second clamping plate 10 is located on the side of the second mounting plate 9 facing the first mounting plate 4. The second threaded plate 3 is mounted on the second clamping plate 10. The second mounting plate 9 and the second clamping plate 10 are slidably connected by dovetail grooves and dovetail sliders respectively provided on both. A second sliding groove 18 extending along the second axis is formed on the second clamping plate 10, and a second locking bolt 11, at least partially capable of extending into the second sliding groove 18, is threaded onto its side wall. The second threaded plate 3 is mounted inside the second clamping plate 10 and is fixedly connected to the second clamping plate 10 by the second locking bolt 11. The second clamping plate 10 is provided with a connecting plate 16. When the second drive mechanism 13 is connected to the second tooth rolling plate 3, the second tooth rolling plate 3 is connected to the second drive mechanism 13 through the second clamping plate 10 and the connecting plate 16. The connecting plate 16 extends along the second axis and in a direction away from the mounting base 1, so that the second drive mechanism 13 can be offset from the positions of the first mounting plate 4, the first clamping plate 5, the second mounting plate 9 and the second clamping plate 10 on the second axis, which facilitates the assembly of the second drive mechanism 13 with the first clamping plate 5.

[0025] Based on the above-mentioned fastener thread rolling system, the thread rolling method involves fixing the first thread rolling plate 2 to the mounting base 1 in a fixed relative position. The driving mechanism includes a base 19, a moving stage 10 that moves relative to the base 19 along a second axis, and a gripper mounted on the moving stage 10. The second thread rolling plate 3 is connected to the gripper of the second driving mechanism 13. The thread rolling method includes: a. Fix the mounting base 1 to the base, and fix the second tooth rolling plate 3 to the clamp; b. Start the second drive mechanism 13 and set the initial speed to make the gripper and the second tooth-rolling plate 3 move upward simultaneously to perform tooth rolling; c. During tooth rubbing, the pressure value P applied by the first drive mechanism 12 to the second tooth rubbing plate 3 is... R (i.e., the radial force of the tooth rolling) reaches its maximum value within time t, P RThe value is obtained by calculating using the following formula:

[0026] Where: t≤1s; P R - Thread rolling radial force, N; L - Thread rolling length, mm; R P0.2 -Specified non-proportional elongation strength, MPa; P - Pitch, mm; d0 - Bolt blank diameter, mm; K1 - Empirical coefficient, its value ranges from 0.3 to 0.7, with 0.5 being optimal; When P R When the maximum value is reached, adjust the tensile force P of the tensile testing machine according to the following relationship. T The magnitude of (i.e., the axial force of the thread rolling):

[0027] Where: P T - Axial force for thread rolling, N; K2 - Empirical coefficient, its value ranges from 0.05 to 0.3, with an optimal value of 0.15; During the bolt threading process, the radial and lateral forces must satisfy the above relationship until the threading is completed. After the threading is completed, the bolt is removed.

[0028] Example 1 The bolt material is 6D10 aluminum alloy, with a yield strength of 400MPa and a tensile strength of 420MPa in the T6 temper. The finished bolt is M8, with a pitch of 1.25mm and a thread length of 40mm. Follow these steps to machine the threads of the M8 bolt: (1) Clamp the device in the tensile testing machine, install the first mounting plate 4 and the second mounting plate 9 into the dovetail groove of the mounting base 1, and place the first mounting plate 4 at about 1 / 3 position on the left side of the mounting base 1. Fix the first positioning block with the first adjusting bolt 8 to restrict the movement of the first mounting plate 4.

[0029] (2) Install the first clamping plate 5 into the first mounting plate 4, adjust its position to the middle, and fix it with the first locking bolt 6. Then install the first threaded die 2 with M8 thread into the first clamping plate 5 and fix it with the first locking bolt 6.

[0030] (3) Install the second clamping plate 10 into the second mounting plate 9, then install the second threaded plate 3 with M8 thread into the second clamping plate 10, slide the second clamping plate 10 to the bottom of the second clamping plate 10, and connect the connecting plate 16 to the jaws in the universal tensile testing machine.

[0031] (4) Fix the first drive mechanism 12 to the base and connect the push rod 14 of the first drive mechanism 12 to the second mounting plate 9 by means of hexagonal bolts.

[0032] (5) The pressure value PR (i.e., the radial force of the tooth rolling) of the transverse hydraulic press was calculated to be 36.54KN and the tensile force PT (i.e., the axial force of the tooth rolling) of the tensile testing machine was 5.48KN.

[0033] (6) Place the fastener 0 to be rolled between the first rolling plate 2 and the second rolling plate 3, and adjust the initial force of the first drive mechanism 12 to 100N, set the initial tension rate of the second drive mechanism 13 to 1mm / s, and quickly apply pressure P from the first drive mechanism 12 through the second drive mechanism 13. R (That is, the radial force of the tooth rolling) is increased to the maximum value of 36.54KN, and then the tensile force is adjusted to 5.48KN. The tooth rolling is continued until it is completed.

[0034] (7) Bolts manufactured using this thread rolling method were inspected for appearance, defects, dimensions and mechanical properties. The results are shown in Table 1.

[0035] Table 1. Inspection results of M8 ordinary threaded bolts

[0036] Example 2 Unlike Example 1, the device uses a thread-rolling plate for M12 threads. By adjusting the pressure of the hydraulic rod, the second clamping plate 10 and the thread-rolling plate move left and right, adjusting the minimum spacing of the thread-rolling plates to 10.5mm. The tensile testing machine speed is set to 1mm / s, and the tensile stroke is 220mm. The bolt is then thread-rolled, and the rolled bolt is removed after the rolling process. After testing, the surface defects, dimensional specifications, and mechanical properties of the M12 bolt all meet the requirements. The bolt material is 6D10 aluminum alloy, with a yield strength of 400MPa and a tensile strength of 420MPa in the T6 state. The finished bolt is M12 with a pitch of 1.75mm and a thread length of 30mm. The thread processing of the M12 bolt is performed according to the following steps: (1) Clamp the device in the tensile testing machine, install the first mounting plate 4 and the second mounting plate 9 into the dovetail groove of the mounting base 1, and place the first mounting plate 4 at about 1 / 3 position on the left side of the mounting base 1. Fix the first positioning block with the first adjusting bolt 8 to restrict the movement of the first mounting plate 4.

[0037] (2) Install the first clamping plate 5 into the first mounting plate 4, adjust its position to the middle, and fix it with the first locking bolt 6. Then install the first threaded die 2 with M8 thread into the first clamping plate 5 and fix it with the first locking bolt 6.

[0038] (3) Install the second clamping plate 10 into the second mounting plate 9, then install the second threaded plate 3 with M8 thread into the second clamping plate 10, slide the second clamping plate 10 to the bottom of the second clamping plate 10, and connect the connecting plate 16 to the jaws in the universal tensile testing machine.

[0039] (4) Fix the first drive mechanism 12 to the base and connect the push rod 14 of the first drive mechanism 12 to the second mounting plate 9 by means of hexagonal bolts.

[0040] (5) The pressure value PR (i.e., the radial force of the tooth rolling) of the transverse hydraulic press was calculated to be 39.90KN and the tensile force PT (i.e., the axial force of the tooth rolling) of the tensile testing machine was 5.99KN.

[0041] (6) Place the fastener 0 to be rolled between the two rolling plates, adjust the initial force of the hydraulic mechanism to 100N, set the initial tensile rate of the tensile testing machine to 1mm / s, and quickly increase the hydraulic pressure PR (i.e. the rolling radial force) to the maximum value of 39.90KN through the tensile testing machine system, then adjust the tensile force to 5.99KN, and continue rolling until it is completed.

[0042] (7) Bolts manufactured using this thread rolling method were inspected for appearance, defects, dimensions and mechanical properties. The results are shown in Table 1.

[0043] Table 2. Inspection Results of M8 Ordinary Threaded Bolts

[0044] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A thread rolling system of a fastener, comprising: a mounting base having a first axis parallel to its upper end surface and a second axis perpendicular to its upper end surface; a first thread rolling plate and a second thread rolling plate, both mounted on the mounting base, the first thread rolling plate and the second thread rolling plate being slidable relative to each other along the first axis and the second axis; a first driving mechanism for controlling the indirect pressure between the first thread rolling plate and the second thread rolling plate along the first axis; a second driving mechanism for driving the first thread rolling plate or the second thread rolling plate to move along the second axis, characterized in that: the first driving mechanism comprises a first actuator and a first acquisition module for acquiring the working parameters of the first actuator; the second driving mechanism comprises a second actuator, a second acquisition module for acquiring the working parameters of the second actuator, and a control module for controlling the action of the second actuator according to the parameters acquired by the second acquisition module, the first acquisition module being electrically connected to the control module, and the control module also controlling the action of the first actuator according to the parameters acquired by the first acquisition module.

2. The thread rolling system of claim 1, wherein: the thread rolling system further comprises a first mounting plate slidably connected to the mounting base along the first axis, and a first clamping plate slidably connected to the first mounting plate along the second axis, the first thread rolling plate being mounted on the first clamping plate.

3. The thread rolling system of claim 2, wherein: a first sliding groove extending along the second axis is formed on the first clamping plate, and at least one first locking bolt is threadedly connected to the side wall of the first sliding groove and capable of extending into the first sliding groove.

4. The thread rolling system of claim 3, wherein: the thread rolling system further comprises a first positioning plate fixedly connected to the lower end of the first mounting plate, and a first adjusting bolt, the first positioning plate being provided with a first waist-shaped hole, and the first adjusting bolt being threadedly connected to the mounting base and extending through the first waist-shaped hole.

5. The thread rolling system of claim 1 wherein: the thread rolling system further comprises a second mounting plate slidably connected to the mounting base along the first axis, and a second clamping plate slidably connected to the second mounting plate along the second axis, the second clamping plate being located on the side of the second mounting plate facing the first mounting plate, and the second thread rolling plate being mounted on the second clamping plate.

6. The thread rolling system of claim 5, wherein: a second sliding groove extending along the second axis is formed on the second clamping plate, and at least one second locking bolt is threadedly connected to the side wall of the second sliding groove and capable of extending into the second sliding groove.

7. The thread rolling system of claim 5, wherein: the second clamping plate is provided with a connecting plate, when the second driving mechanism is connected to the second thread rolling plate, the second thread rolling plate is connected to the second driving mechanism through the second clamping plate and the connecting plate, and the connecting plate extends along the second axis and away from the mounting base.

8. The thread rolling system of claim 1 wherein: the first driving mechanism is a hydraulic device, and the first acquisition module is a pressure sensor mounted in the cylinder of the hydraulic device.

9. The thread rolling system of claim 8, wherein: the second driving mechanism is a tensile testing machine, the thread rolling system further comprises an oil delivery pipe connected between the first driving mechanism and the second driving mechanism, and the hydraulic oil in the cylinder is provided by the tensile testing machine.

10. A thread rolling method for a thread rolling system of a fastener based on the claim 9, characterized by: The first die plate is fixed in position relative to the mounting base, the drive mechanism includes a base, a moving table that moves along a second axis relative to the base, and a clamp jaw provided on the moving table, the second die plate is connected to the clamp jaw of the second drive mechanism, and the die rolling method includes: a. fixing the mounting base to the base and fixedly connecting the second die plate to the clamp jaw; b. starting the second drive mechanism and setting an initial speed such that the clamp jaw and the second die plate move upward at the same time to roll the die; c. the value of the pressure P exerted by the first drive mechanism on the second thread rolling plate when rolling the thread R reaches a maximum value, P R the value is obtained by calculating from the formula: ； where: t < 1 s; P R - Radial force of the thread, N; L - Thread length, mm; R P0.2 - Specified non-proportional elongation strength, MPa; P - Pitch, mm; d0 - Bolt blank diameter, mm; K1 - Empirical coefficient; When P R reaches the maximum value, the magnitude of the tensile force P T of the tensile testing machine is adjusted according to the following relationship: ； where: P T - writhing axial force, N; K2 - empirical coefficient; During the process of rolling the bolt, the radial force and the transverse force satisfy the above relationship until the rolling is completed, and the bolt is removed after the rolling is completed.

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