Electric auxiliary stretch-bending forming device and stretch-bending method for metal profile

Abstract

The invention relates to a metal profile electric auxiliary stretch-bending forming device and a stretch-bending method, and belongs to the technical field of metal profile plastic stretch-bending forming, the device comprises a workbench, a detection table and a stretch-bending device, and the detection table and the stretch-bending device are arranged on the workbench. The stretch bending method comprises the steps that firstly, the detection table and the stretch bending device are fixed to the workbench; secondly, the to-be-treated profile is fixed to a workbench through a clamping mechanism; and step 3, starting the pulse power supply device. Through the arrangement of the stretch-bending device, the metal profile can be subjected to stretch-bending forming through electric assistance, meanwhile, by controlling the electric parameters such as the current density and the duty ratio conducted by the profile, an electro-thermal coupling field in the stretch-bending forming process is affected, and the forming effect is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic stretch-bending forming of metal profiles, and in particular relates to an electrically assisted stretch-bending forming device and a stretch-bending method for metal profiles. Background Art

[0002] Lightweight and high-strength alloy bending parts such as titanium alloy and aluminum alloy have poor forming performance at room temperature and are prone to defects such as cracks and severe springback, so they are mostly formed by hot bending. However, the hot bending process has problems such as long processing cycle, high energy consumption, coarse grains of formed parts, and severe surface oxidation. The electrically assisted bending process uses the Joule heating effect and electroplastic effect of pulsed current to assist the plastic forming of difficult-to-deform metals, which can further reduce deformation resistance, reduce energy consumption, and improve production efficiency. It can be formed in a lower temperature range and is expected to become a fast, low-cost green bending technology.

[0003] Different from the traditional hot stretch bending process, the new electrically assisted stretch bending process requires plastic processing of the workpiece while ensuring the conduction of pulse current. The deformation process involves multi-field coupling including electric and thermal forces. Currently, the forming equipment and methods are mainly concentrated on hot stretch bending. There is relatively little research on electrically assisted stretch bending, and industrializable process equipment has not yet been developed.

[0004] In order to solve the problem of electrically assisted stretch bending of difficult-to-deform materials such as the above-mentioned titanium alloy, it is necessary to design a metal profile electrically assisted stretch bending forming device and a stretch bending method to achieve efficient and low-cost electrically assisted stretch bending of metal profiles. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a metal profile electrically assisted stretch-bending forming device and a stretch-bending method. By setting the stretch-bending device, the metal profile can be stretched and bent with electrical assistance. At the same time, by controlling the electrical parameters such as the current density and duty cycle of the profile conduction, the electro-thermal-mechanical coupling field in the stretch-bending process is affected to improve the forming effect.

[0006] To achieve the above object, the present invention discloses the following technical solution:

[0007] In one aspect, the present invention provides a metal profile electrically assisted bending forming device, which comprises a workbench, a detection table and a bending device, wherein the detection table and the bending device are arranged on the workbench;

[0008] The testing platform comprises a support plate, a bending punch and a mold pad, wherein the first surface of the support plate is fixedly connected to one surface of the workbench through a plurality of support columns, the second surface of the support plate is connected to the first surface of the mold pad, and the second surface of the mold pad is connected to one side of the bending punch;

[0009] The stretching and bending device comprises a clamping mechanism, a stretching hydraulic cylinder, a stretching loading mechanism, a bending loading mechanism, a rotating arm, a bending hydraulic cylinder and a connecting platform; the two ends of the profile to be processed are respectively fixedly connected to the first ends of the two clamping mechanisms, the second end of the clamping mechanism is connected to the output end of the stretching hydraulic cylinder, the stretching hydraulic cylinder is arranged inside the stretching loading mechanism, the stretching loading mechanism is arranged on the rotating arm, one end of the rotating arm is connected to the workbench through a connecting device, and the connecting device is arranged below the support plate, the first end of the bending loading mechanism is rotatably connected to the side wall of the stretching loading device and the rotating arm, the second end of the bending loading mechanism is telescopically connected to the first end of the bending hydraulic cylinder, and the second end of the bending hydraulic cylinder is rotatably connected to the connecting platform;

[0010] The clamping mechanism includes a coupling, a mounting block, a limiting bolt, a first pressing plate, a second pressing plate, a clamping oil cylinder and an insulating component. The mounting block is a groove structure. The insulating component is laid on the inner side wall of the mounting block. The first end of the coupling is connected to the output end of the stretching hydraulic cylinder, and the second end of the coupling is connected to the side wall of the mounting block. The first pressing plate and the second pressing plate are symmetrically arranged inside the mounting block. The limiting bolt passes through the first end of the mounting block and is connected to the first pressing plate. The clamping oil cylinder is arranged at the second end of the mounting block, and the output end of the clamping oil cylinder passes through the second end of the mounting block and is fixedly connected to the second pressing plate.

[0011] The ends of the profile to be processed are clamped by the first pressing plate and the second pressing plate respectively, so that the ends of the profile to be processed pass through the notch of the mounting block and are fixed inside the mounting block.

[0012] Furthermore, the bending punch, the support plate and the mold pad are connected by a plurality of screws.

[0013] Furthermore, the bending punch is a trapezoidal structure with an arc, and one end with the arc contacts the side wall of the profile to be processed.

[0014] Furthermore, the stretch-bending device also includes a pulse power supply device, and the positive and negative electrodes of the pulse power supply device are respectively connected to the two ends of the profile to be processed.

[0015] Furthermore, the connecting device includes a rotating shaft and a thrust bearing, the outer side of the thrust bearing is connected to one end of the tensile loading mechanism, and the inner side of the thrust bearing is sleeved on the rotating shaft, so that the tensile loading mechanism can rotate with the connecting device as the center.

[0016] Furthermore, the insulating assembly includes an insulating partition and an insulating fixing block, the insulating partition is arranged at the bottom of the groove structure, and the insulating fixing block is arranged on the side wall of the groove structure.

[0017] Furthermore, insulating pads are provided between the limiting bolt and the first pressing plate and between the output end of the clamping oil cylinder and the second pressing plate.

[0018] Furthermore, the bending loading mechanism is movably connected to the side walls of the tensile loading device and the rotating arm through cylindrical pins, so that the bending loading mechanism, the tensile loading mechanism and the rotating arm are not restricted by angles.

[0019] In another aspect, the present invention provides a bending method for a metal profile electrically assisted bending forming device, comprising the following steps:

[0020] Step 1: Fix the testing table and the bending device on the workbench;

[0021] Step 2: Fix the profile to be processed on the workbench through a clamping mechanism;

[0022] Step 3: Turn on the pulse power supply device to conduct the pulse current to the profile to be processed, wait for the profile to be processed to heat up, and then adjust the pulse current density to control the pure electro-plastic effect so that the profile to be processed is in a softened state, reduce the yield stress of the profile to be processed, and adjust the duty cycle to control the temperature of the profile to be processed so that the temperature is kept within the forming temperature range;

[0023] Step 4: Turn on the stretching hydraulic cylinder to pre-stretch the profile to be processed to make it reach a yield state and maintain the tension;

[0024] Step 5, start the bending hydraulic cylinder, so that the bending hydraulic cylinder pushes the bending loading mechanism to drive the profile to be processed to bend, so that the side wall of the profile to be processed is completely in contact with the curved end surface of the bending punch;

[0025] Step 6: Start the stretching hydraulic cylinder to stretch the profile to be processed for 1.1 to 1.3σs;

[0026] Step 7: Close the stretching hydraulic cylinder to allow the profile to rebound;

[0027] Step 8. Turn off the pulse power supply device to complete the profile bending.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The clamping mechanism in the stretching and bending device of the present invention can effectively clamp the profile to be processed, and then achieve stretching and bending of the profile to be processed through the cooperation of the stretching hydraulic cylinder and the bending hydraulic cylinder; at the same time, a pulse power supply device is also provided in the stretching and bending device, so that the device can heat the profile to be processed during the stretching and bending process, so that the profile to be processed can be in a soft state, which is convenient for stretching and bending.

[0030] The clamping mechanism of the present invention facilitates installation and replacement of the profile to be processed through the cooperation of the limiting bolts, the first pressing plate, the second pressing plate and the clamping oil cylinder, thereby making the tensile bending test quick and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of the electric-assisted stretch-bending device of the present invention connected to a pulse power supply;

[0032] Figure 2 It is a front schematic diagram of the electric-assisted stretch-bending forming device of the present invention;

[0033] Figure 3 It is a schematic diagram of the insulating cylinder clamp of the electric-assisted stretch-bending forming device of the present invention.

[0034] Some of the drawings in the accompanying drawings are described as follows:

[0035] 1. Support plate; 2. Bending punch; 3. Die pad; 4. Clamping mechanism; 5. Profile to be processed; 6. Screw; 7. Rotating shaft; 8. Thrust bearing; 9. Rotating arm; 10. Stretching loading mechanism; 11. Workbench; 12. Support column; 13. Bending loading mechanism; 14. Cylindrical pin; 15. Pulse power supply device; 16. Limit bolt; 17. First insulating spacer; 18. Second insulating spacer; 19. Insulating partition; 20. Insulating fixing block; 21. Mounting block; 22. Coupling; 23. Clamping cylinder; 24. First pressure plate; 25. Second pressure plate; 26. Stretching hydraulic cylinder; 27. Bending hydraulic cylinder. DETAILED DESCRIPTION

[0036] The exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0037] The present invention provides a metal profile electric assisted stretch bending forming process and equipment, such as Figure 1-Figure 3As shown, it includes a workbench 11, a testing table and a stretching and bending device, and the testing table and the stretching and bending device are arranged on the workbench 11; the testing table includes a support plate 1, a bending punch 2 and a mold pad 3, the first surface of the support plate 1 is fixedly connected to one surface of the workbench 11 through a plurality of support columns 12, the second surface of the support plate 1 is connected to the first surface of the mold pad 3, and the second surface of the mold pad 3 is connected to one side of the bending punch 2.

[0038] The stretching and bending device includes a clamping mechanism 4, a stretching hydraulic cylinder 26, a stretching loading mechanism 10, a bending loading mechanism 13, a rotating arm 9, a bending hydraulic cylinder 27 and a connecting platform; the two ends of the profile 5 to be processed are respectively fixedly connected to the first ends of the two clamping mechanisms 4, the second end of the clamping mechanism 4 is connected to the output end of the stretching hydraulic cylinder 26, the stretching hydraulic cylinder 26 is arranged inside the stretching loading mechanism 10, the stretching loading mechanism 10 is arranged on the rotating arm 9, one end of the rotating arm 9 is connected to the workbench 11 through a connecting device, and the connecting device is arranged below the support plate 1, the first end of the bending loading mechanism 13 is rotatably connected to the side wall of the stretching loading device and the rotating arm 9, the second end of the bending loading mechanism 13 is telescopically connected to the first end of the bending hydraulic cylinder 27, and the second end of the bending hydraulic cylinder 27 is rotatably connected to the connecting platform.

[0039] The clamping mechanism 4 includes a coupling 22, a mounting block 21, a limiting bolt 16, a first pressure plate 24, a second pressure plate 25, a clamping cylinder 23 and an insulating component. The mounting block 21 is a groove structure, and the insulating component is laid on the inner side wall of the mounting block 21. The first end of the coupling 22 is connected to the output end of the stretching hydraulic cylinder 26, and the second end of the coupling 22 is connected to the side wall of the mounting block 21. The first pressure plate 24 and the second pressure plate 25 are symmetrically arranged inside the mounting block 21. The limiting bolt 16 passes through the first end of the mounting block 21 and is connected to the first pressure plate 24. The clamping cylinder 23 is arranged at the second end of the mounting block 21, and the output end of the clamping cylinder 23 passes through the second end of the mounting block 21 and is fixedly connected to the second pressure plate 25.

[0040] The ends of the processed profile 5 are clamped by the first pressing plate 24 and the second pressing plate 25 respectively, so that the ends of the processed profile 5 pass through the notch of the mounting block 21 and are fixed inside the mounting block 21 .

[0041] The bending punch 2 , the support plate 1 and the die backing plate 3 are connected by a plurality of screws 6 .

[0042] The bending punch 2 is a trapezoidal structure with an arc, and one end with the arc contacts the side wall of the profile 5 to be processed.

[0043] The stretch-bending device further comprises a pulse power supply device 15 , the positive and negative electrodes of which are respectively connected to the two ends of the profile 5 to be processed.

[0044] The connecting device includes a rotating shaft 7 and a thrust bearing 8. The outer side of the thrust bearing 8 is connected to one end of the tensile loading mechanism 10, and the inner side of the thrust bearing 8 is sleeved on the rotating shaft 7, so that the tensile loading mechanism 10 can rotate with the connecting device as the center.

[0045] The insulating assembly includes an insulating partition 19 and an insulating fixing block 20. The insulating partition 19 is arranged at the bottom of the groove structure, and the insulating fixing block 20 is arranged on the side wall of the groove structure.

[0046] A first insulating spacer 17 is disposed between the limiting bolt 16 and the first pressing plate 24 .

[0047] A second insulating spacer 18 is provided between the output end of the clamping oil cylinder 23 and the second pressing plate 25 .

[0048] The bending loading mechanism 13 is movably connected to the side wall of the tensile loading device and the rotating arm 9 through a cylindrical pin 14, so that the bending loading mechanism 13, the tensile loading mechanism 10 and the rotating arm 9 are not restricted by angles.

[0049] In another aspect, the present invention provides a bending method for a metal profile electrically assisted bending forming device, comprising the following steps:

[0050] Step 1: Fix the testing table and the bending device on the workbench 11.

[0051] Step 2: Fix the profile 5 to be processed on the workbench 11 through the clamping mechanism 4.

[0052] Step three, turn on the pulse power supply device 15 to make the profile 5 to be processed conduct the pulse current, wait for the profile 5 to be processed to heat up, and then adjust the pulse current density to control the pure electroplastic effect so that the profile 5 to be processed is in a softened state, reduce the yield stress of the profile 5 to be processed, and adjust the duty cycle to control the temperature of the profile 5 to be processed so that its temperature is kept within the forming temperature range.

[0053] Step 4: Start the stretching hydraulic cylinder 26 so that the stretching hydraulic cylinder 26 pre-stretches the profile 5 to be processed to make it reach a yield state and maintain the tension.

[0054] Step 5: Turn on the bending hydraulic cylinder 27 so that the bending hydraulic cylinder 27 pushes the bending loading mechanism 13 to drive the processed profile 5 to bend, so that the side wall of the processed profile 5 is completely in contact with the curved end surface of the bending punch 2.

[0055] Step 6: Start the stretching hydraulic cylinder 26 so that the stretching hydraulic cylinder 26 performs supplementary stretching of the profile 5 to be processed for 1.1 to 1.3σs.

[0056] Step 7: Close the stretching hydraulic cylinder 26 to allow the profile to rebound.

[0057] Step 8: Turn off the pulse power supply device 15 to complete the bending of the profile.

[0058] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A metal profile electrically assisted stretch bending device, characterized in that: It comprises a workbench, a testing platform and a bending device, wherein the testing platform and the bending device are arranged on the workbench; The testing platform comprises a support plate, a bending punch and a mold pad, wherein the first surface of the support plate is fixedly connected to one surface of the workbench through a plurality of support columns, the second surface of the support plate is connected to the first surface of the mold pad, and the second surface of the mold pad is connected to one side of the bending punch; The stretching and bending device comprises a clamping mechanism, a stretching hydraulic cylinder, a stretching loading mechanism, a bending loading mechanism, a rotating arm, a bending hydraulic cylinder and a connecting platform; the two ends of the profile to be processed are respectively fixedly connected to the first ends of the two clamping mechanisms, the second end of the clamping mechanism is connected to the output end of the stretching hydraulic cylinder, the stretching hydraulic cylinder is arranged inside the stretching loading mechanism, the stretching loading mechanism is arranged on the rotating arm, one end of the rotating arm is connected to the workbench through a connecting device, and the connecting device is arranged below the support plate, the first end of the bending loading mechanism is rotatably connected to the side wall of the stretching loading device and the rotating arm, the second end of the bending loading mechanism is telescopically connected to the first end of the bending hydraulic cylinder, and the second end of the bending hydraulic cylinder is rotatably connected to the connecting platform; The clamping mechanism includes a coupling, a mounting block, a limiting bolt, a first pressing plate, a second pressing plate, a clamping oil cylinder and an insulating component. The mounting block is a groove structure. The insulating component is laid on the inner side wall of the mounting block. The first end of the coupling is connected to the output end of the stretching hydraulic cylinder, and the second end of the coupling is connected to the side wall of the mounting block. The first pressing plate and the second pressing plate are symmetrically arranged inside the mounting block. The limiting bolt passes through the first end of the mounting block and is connected to the first pressing plate. The clamping oil cylinder is arranged at the second end of the mounting block, and the output end of the clamping oil cylinder passes through the second end of the mounting block and is fixedly connected to the second pressing plate. The ends of the profile to be processed are clamped by the first pressing plate and the second pressing plate respectively, so that the ends of the profile to be processed pass through the notch of the mounting block and are fixed inside the mounting block.

2. The metal profile electrically assisted stretch bending device according to claim 1, characterized in that: The bending punch, the support plate and the mold pad are connected by a plurality of screws.

3. The metal profile electrically assisted stretch bending device according to claim 1, characterized in that: The bending punch is a trapezoidal structure with an arc, and one end with the arc contacts the side wall of the profile to be processed.

4. The metal profile electrically assisted stretch bending device according to claim 1, characterized in that: The stretch-bending device also includes a pulse power supply device, and the positive and negative electrodes of the pulse power supply device are respectively connected to the two ends of the profile to be processed.

5. The metal profile electrically assisted stretch bending device according to claim 1, characterized in that: The connecting device includes a rotating shaft and a thrust bearing, the outer side of the thrust bearing is connected to one end of the tensile loading mechanism, and the inner side of the thrust bearing is sleeved on the rotating shaft, so that the tensile loading mechanism can rotate with the connecting device as the center.

6. The metal profile electrically assisted stretch bending device according to claim 1, characterized in that: The insulating assembly comprises an insulating partition and an insulating fixing block, wherein the insulating partition is arranged at the bottom of the groove structure, and the insulating fixing block is arranged on the side wall of the groove structure.

7. The metal profile electrically assisted stretch bending device according to claim 1, characterized in that: Insulating pads are arranged between the limiting bolt and the first pressing plate and between the output end of the clamping oil cylinder and the second pressing plate.

8. The metal profile electrically assisted stretch bending device according to claim 1, characterized in that: The bending loading mechanism is movably connected to the side walls of the tensile loading device and the rotating arm through cylindrical pins, so that the bending loading mechanism, the tensile loading mechanism and the rotating arm are not restricted by angles.

9. A bending method for a metal profile electrically assisted bending forming device according to any one of claims 1 to 7, characterized in that: It includes the following steps: Step 1: Fix the testing table and the bending device on the workbench; Step 2: Fix the profile to be processed on the workbench through a clamping mechanism; Step 3: Turn on the pulse power supply device to conduct the pulse current to the profile to be processed, wait for the profile to be processed to heat up, and then adjust the pulse current density to control the pure electro-plastic effect so that the profile to be processed is in a softened state, reduce the yield stress of the profile to be processed, and adjust the duty cycle to control the temperature of the profile to be processed so that the temperature is kept within the forming temperature range; Step 4: Turn on the stretching hydraulic cylinder to pre-stretch the profile to be processed to make it reach a yield state and maintain the tension; Step 5, start the bending hydraulic cylinder, so that the bending hydraulic cylinder pushes the bending loading mechanism to drive the profile to be processed to bend, so that the side wall of the profile to be processed is completely in contact with the curved end surface of the bending punch; Step 6: Start the stretching hydraulic cylinder to stretch the profile to be processed for 1.1 to 1.3σs; Step 7: Close the stretching hydraulic cylinder to allow the profile to rebound; Step 8. Turn off the pulse power supply device to complete the profile bending.

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