Progressive partial forging and bending forming die and method for u-shaped connecting piece

Abstract

A U-shaped connecting piece progressive local forging and bending forming die and method, comprising a die, a front blank holder punch, a forming punch, a rear blank holder punch arranged in the die in sequence, and a bending control device arranged at the end of the die, wherein: the upper die plate drives the front blank holder punch, the rear blank holder punch and the forming punch to press down through the front hydraulic cylinder and the rear hydraulic cylinder, and the blank is input from the first end side of the die and is intermittently output to the end bending control device. The present application can reduce the forming load, reduce the manufacturing cycle and the die specification, improve the material utilization rate and the component performance, and promote the high performance, low cost and short process preparation of the U-shaped connecting piece.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal plastic working, and particularly relates to a U-shaped connecting piece progressive local forging and bending forming die and method. BACKGROUND

[0002] In the forming of the U-shaped connecting piece, the integral forging and integral draw bending processes have the disadvantages of high forming tonnage and large die structure; the traditional local forging is prone to defects such as folding and penetrating rib; and the continuous bending process is limited by factors such as die structure, and is prone to bending instability, profile distortion or convex bundle of the component. SUMMARY

[0003] The application provides a U-shaped connecting piece progressive local forging and bending forming die and method, which can reduce the forming load, shorten the manufacturing cycle and die specification, improve the material utilization rate and component performance, and promote the high-performance, low-cost and short-process preparation of the U-shaped connecting piece.

[0004] The application is achieved by the following technical scheme:

[0005] The application relates to a U-shaped connecting piece progressive local forging and bending forming die, which comprises a die, a front blank holder punch arranged inside the die in sequence, a forming punch, a rear blank holder punch and a bending control device arranged at the end of the die, wherein: the upper die plate drives the front blank holder punch, the rear blank holder punch and the forming punch to press down through the front hydraulic cylinder and the rear hydraulic cylinder, and the blank is input from the first side of the die and is intermittently output to the bending control device at the end.

[0006] The bending control device comprises a rotating base, a pair of main control arms arranged on the rotating base, corresponding auxiliary control arms connected with the main control arms, and inner bending rollers and outer bending rollers vertically arranged between the pair of main control arms and the auxiliary control arms, wherein: the inner bending rollers and the outer bending rollers revolve around the rotating base while rotating.

[0007] The revolution is used for adjusting the length of the upper main control arm and the lower main control arm to control the bending forming of the component according to the curvature radius of the target component.

[0008] The main control arms and the auxiliary control arms are telescopically connected, and the distance between the main control arms and the auxiliary control arms is determined according to the width of the component.

[0009] The die surface is determined by the outer contour of the U-shaped connecting piece, and the length of the die is determined by the total length of the installed front blank holder punch, the forming punch and the rear blank holder punch.

[0010] The strokes of the front hydraulic cylinder and the rear hydraulic cylinder are greater than or equal to the amount of single blank pressing; there is a height difference between the bottom of the front edge pressing punch and the bottom of the rear edge pressing punch, and the height difference is equal to the amount of single blank pressing.

[0011] The working surfaces of the front pressing punch, forming punch and rear pressing punch are the same, and the working surfaces are determined by the shape of the inner components of the adjacent webs of the U-shaped connector; the forming punch is located between the front pressing punch and the rear pressing punch, and there is a gap between the adjacent molds, and the size of the gap is determined by the thickness of the webs of the U-shaped connector.

[0012] The front side of the die is provided with a feeding device to realize horizontal quantitative movement of the blank. The feeding distance is the spacing between adjacent web reinforcement ribs of the U-shaped connector to prevent the forming punch and the rear edge pressing punch from pressing the web reinforcement ribs of the U-shaped connector.

[0013] The present invention relates to a method for progressive local forging and bending of a U-shaped connector based on the above-mentioned die, comprising:

[0014] Step 1: The feeding device clamps the end of the blank away from the die and pushes the blank through the input end of the die to the bottom of the forming punch. The press is started and moves downward through the upper template until the front edge pressing punch contacts the blank. At this time, the rear edge pressing punch, outer bending roller and inner bending roller are not in effect.

[0015] Step 2: The press continues to move downward until the forming punch contacts the blank. During this process, the front hydraulic cylinder is pushed back and the front blank holding punch continuously outputs blank holding force.

[0016] Step 3: The press moves downward again, and the forming punch partially loads the blank to complete the first step of forming the blank. The front hydraulic cylinder continues to push back, and the front blank holding punch continues to output the blank holding force.

[0017] Step 4: The press returns and the front hydraulic cylinder pushes out. After the press returns, the feeding device starts and the blank is quantitatively moved to the next area to be deformed. The blank movement distance is determined by the spacing between the adjacent web reinforcement ribs of the U-shaped connector.

[0018] Step 5: After feeding is complete, the press descends again. The front blank holder contacts the blank again as the press descends, while the rear blank holder contacts the already formed area. The press continues descending until the forming punch contacts the blank. During this process, the front and rear hydraulic cylinders continuously push back, and the front and rear blank holders apply a blanking force to the undeformed and deformed areas of the blank, respectively. As the press continues descending, the forming punch applies localized load to the blank, causing deformation and completing the second forming step. During this process, the outer and inner bending rollers remain inactive, as the material has not yet reached the area where they are located.

[0019] Step 6: The press returns, and the front hydraulic cylinder and the rear hydraulic cylinder are pushed out; after the press returns, the feeding device is started, and the blank is quantitatively moved to the next area to be deformed;

[0020] Step 7: The press moves downward, and the front and rear pressing punches apply pressing forces to the undeformed and formed areas of the component respectively under the action of the front and rear hydraulic cylinders; the press continues to move downward, and the forming punch approaches the blank to form the blank below. During this process or after the forming punch completes the forming of the blank, the bending control device is turned on, and the inner and outer bending rollers bend the formed component under the action of the bending control device; in this step, both local forming and local bending of the component occur.

[0021] Step 8: The press returns, the front hydraulic cylinder and the rear hydraulic cylinder are pushed out, and the inner bending roller and the outer bending roller are controlled by the bending control device to return to their original positions; after the press returns, the feeding device is started, and the blank is quantitatively moved to the next area to be deformed;

[0022] Step 9: Repeat steps 7 and 8 until all the ribs of the U-shaped connector are formed and the bending of the component is achieved.

[0023] Technical Effects

[0024] The present invention controls material flow based on the elastic compensation function of the hydraulic system and three-dimensional compressive stress, and cooperates with the bending method of the revolution-passive rotation composite motion mode to divide the overall closed forging and overall stretch-bending process into multiple local closed forging and local closed bending forming steps, which greatly shortens the component preparation cycle, avoids multiple heating of components between multiple processes, and reduces the energy consumption and manufacturing cost of the components; automatically compensates for material thickness changes through the hydraulic cylinder stroke difference to ensure that the clamping force of each step is balanced, while avoiding the stress concentration problem caused by traditional overall clamping; significantly reduces the overall mold specifications and forming tonnage, realizes the ability of small-tonnage equipment to manufacture large components, and solves the problems of lateral flow of materials in traditional local forging forming and surface distortion or convex hull caused by local lack of mold constraints in traditional continuous bending; solves the problem that traditional continuous bending method is not suitable for bending of complex profiles; replaces the static friction in the traditional continuous bending process or the dynamic friction of active rotation with the dynamic friction of the staged passive rotation method, significantly reduces the forming resistance of the component during the bending process, and solves the problem of surface scratches on complex profiles during the bending process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the mold of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the U-shaped connector of the present invention;

[0027] Figure 3This is a schematic diagram of the structure of the inner and outer bending rollers of the present invention;

[0028] Figure 4 This is a schematic diagram of the front hydraulic cylinder and the front edge-pressing punch structure of the present invention;

[0029] Figure 5 Schematic diagram of the die structure of the present invention;

[0030] Figure 6 Flowchart of the present invention;

[0031] Figure 7 It is an embodiment effect diagram;

[0032] In the figure: 1 feeding device, 2 blank, 3 front edge-holding punch, 4 front hydraulic cylinder, 5 die, 6 forming punch, 7 rear hydraulic cylinder, 8 rear edge-holding punch, 9 inner bending roller, 10 outer bending roller, 11 upper template, 12 rotating base, 13 upper main control arm, 14 lower main control arm, 15 upper auxiliary control arm, 16 lower auxiliary control arm. DETAILED DESCRIPTION

[0033] like Figure 1-Figure 5 As shown, this embodiment involves a progressive local forging and bending forming die for a U-shaped connector, including: a die 5, a front pressure punch 3, a forming punch 6 and a rear pressure punch 8 sequentially arranged inside the die 5, a feeding device 1 arranged at the front side of the die 5, and a bending control device relatively rotatingly arranged at the end of the die 5, wherein: the upper template 11 drives the front pressure punch 3 and the rear pressure punch 8 through the front hydraulic cylinder 4 and the rear hydraulic cylinder 7 respectively and drives the forming punch 6 to press down, and the blank 2 is pushed horizontally from the side of the head end of the die 5 through the feeding device 1 and intermittently output to the end bending control device.

[0034] The bending control device includes: a rotating base 12, a pair of main control arms 13 and 14 arranged thereon and corresponding auxiliary control arms 15 and 16 connected thereto, and an inner bending roller 9 and an outer bending roller 10 respectively vertically arranged between the pair of main control arms and the auxiliary control arms, wherein: the inner bending roller 9 cooperates with the upper main control arm 13 and the lower main control arm 14 via a shaft sleeve structure, and the outer bending roller 10 cooperates with the upper auxiliary control arm 15 and the lower auxiliary control arm 16 via a shaft sleeve structure, and the inner bending roller 9 and the outer bending roller 10 revolve around the rotating base 12, and the revolution radius of the inner bending roller 9 and the outer bending roller 10 is controlled by the rotating base 12 by adjusting the length of the upper main control arm 13 and the lower main control arm 14 according to the curvature radius of the target component, thereby realizing the bending forming of the component.

[0035] like Figure 3As shown, both the inner and outer bending rollers 9 and 10 utilize an I-shaped cross-section sleeve structure. Their semi-enclosed shape matches the component's outer contour, addressing deformation instability caused by uneven deformation inside and outside the component during bending. The spacing between the inner and outer bending rollers 9 and 10 can be determined by adjusting the lengths of the upper and lower auxiliary control arms 15 and 16. Both rollers can rotate about their central axis, replacing static friction with dynamic friction, thus preventing surface scratches during bending.

[0036] like Figure 5 As shown, the profile of the die 5 is determined by the outer contour of the U connector, and the length of the die 5 is determined by the total length of the front pressing punch 3, the forming punch 6 and the rear pressing punch 8 after installation;

[0037] The stroke of the front hydraulic cylinder 4 and the rear hydraulic cylinder 7 is greater than or equal to the pressing amount of the single blank 2; there is a height difference between the bottom of the front pressing punch 3 and the bottom of the rear pressing punch 8, and the height difference is equal to the pressing amount of the single blank 2;

[0038] The front pressing punch 3, the forming punch 6 and the rear pressing punch 8 have the same working profile, which is determined by the shape of the inner components of the adjacent webs of the U-shaped connector. The forming punch 6 is located between the front pressing punch 3 and the rear pressing punch 8, and there is a gap between the adjacent molds, the size of which is determined by the thickness of the webs of the U-shaped connector.

[0039] A feeding device 1 is provided on the front side of the die to realize horizontal quantitative movement of the blank 2. The feeding distance is the spacing between adjacent web reinforcement ribs of the U-shaped connector to prevent the forming punch 6 and the rear edge pressing punch 8 from pressing the web reinforcement ribs of the U-shaped connector.

[0040] like Figure 2 As shown, the U-shaped connector is made of 1 series aluminum alloy, and web reinforcement ribs are distributed locally on the component. The spacing between adjacent web reinforcement ribs is 100 mm and the thickness is 5 mm.

[0041] like Figure 6 As shown in FIG. 1 , a method for progressive local forging and bending of a U-shaped connector based on the above-mentioned die in this embodiment includes:

[0042] Step 1: The feeding device 1 clamps the end of the blank away from the die 5 and pushes the blank 2 through the input end of the die 5 to the bottom of the forming punch 6. The press is started and moves downward through the upper template until the front edge pressing punch 3 contacts the blank 2. At this time, the rear edge pressing punch 8, the outer bending roller 10 and the inner bending roller 9 do not work.

[0043] Step 2: The press continues to move downward until the forming punch 6 contacts the blank 2. During this process, the front hydraulic cylinder 4 is pushed back, and the front blank holding punch 3 continuously outputs a blank holding force to the blank 2.

[0044] Step 3: The press continues to move downward, the forming punch 6 partially loads the blank 2, and the first forming step of the blank 2 is completed. The front hydraulic cylinder 4 continues to push back, and the front blank holding punch 3 continues to output the blank holding force.

[0045] Step 4: The press returns, and the front hydraulic cylinder 4 is ejected; after the press returns, the feeding device 1 is started, and the blank 2 is quantitatively moved to the next area to be deformed;

[0046] Step 5: After feeding is completed, the press descends again. The front pressing punch 3 contacts the blank 2 again as the press descends, while the rear pressing punch 8 contacts the already formed area. The press continues to descend until the forming punch 6 contacts the blank 2. During this process, the front hydraulic cylinder 4 and the rear hydraulic cylinder 7 continuously push back, and the front pressing punch 3 and the rear pressing punch 8 continue to apply a pressing force to the undeformed and deformed areas of the blank 2, respectively. As the press continues to descend, the forming punch 6 locally loads the blank 2, causing the material to deform, completing the second forming step. During this process, since the material has not yet reached the area of ​​the outer bending roller 10 and the inner bending roller 9, the outer bending rollers 10 and 9 are still not active.

[0047] Step 6: The press returns, and the front hydraulic cylinder 4 and the rear hydraulic cylinder 7 are pushed out; after the press returns, the feeding device 1 is started, and the blank 2 is quantitatively moved to the next area to be deformed;

[0048] Step 7, the press moves downward, and the front pressing punch 3 and the rear pressing punch 8 apply pressing force to the undeformed area and the formed area of ​​the component under the action of the front hydraulic cylinder 4 and the rear hydraulic cylinder 7 respectively; the press continues to move downward, and the forming punch 6 approaches the blank 2 to form the blank 2 below. During this process or after the forming punch 6 completes the forming of the blank 2, the rotating base 12 is turned on, and the inner bending roller 9 and the outer bending roller 10 bend the formed component under the action of the rotating base 12; in this step, local forming and local bending of the component both occur.

[0049] Step 8: The press returns, the front hydraulic cylinder 4 and the rear hydraulic cylinder 7 are pushed out, and the inner bending roller 9 and the outer bending roller 10 are controlled by the rotating base 12 to return to their original positions; after the press returns, the feeding device 1 is started, and the blank 2 is moved quantitatively to the next area to be deformed;

[0050] Step 9: Repeat steps 7 and 8 until all the ribs of the U-shaped connector are formed and the bending of the component is achieved.

[0051] In steps 1 to 9, the downward speed of the press ranges from 0.1 to 15 mm / s.

[0052] In steps 2 to 9, the hydraulic tonnage range of the front hydraulic cylinder 4 and the rear hydraulic cylinder 7 is 0.5 to 50 tons, and the stroke is 0 to 50 mm.

[0053] In steps 7 to 9, the angular velocity of the rotating base 12 is 0.1-10 rad / s, the revolution radius is 200-2000 mm, and the radial distance between the inner bending roller 9 and the outer bending roller 10 is 30-100 mm.

[0054] Through specific simulation experiments, at room temperature, progressive local forging and bending forming were carried out with parameters such as billet movement distance of 100 mm, pressing speed of 1 mm / s, angular velocity of 0.1 rad / s, blank holder force of 30 tons, pressing amount of 7.5 mm and revolution radius of 1000 mm: the U-shaped connector can be stably formed in each forming step, and no obvious local loading deformation defects such as folding and reinforcing and bending instability defects are found; the distribution of equivalent strain in each region of the component is relatively uniform, indicating that the forming process method is relatively stable and reliable, and the forming uniformity of the component is good.

[0055] like Figure 7 The figure shows the result of the progressive local forging and bending forming of the U-shaped connector. In the first three loading steps, since the component was not sent to the action area of ​​the inner bending roller 9 and the outer bending roller 10, only local forging and forming occurred during the first three loading steps. After the third loading step, the component has been sent to the action area of ​​the inner bending roller 9 and the outer bending roller 10. Therefore, the fourth loading step and subsequent loading steps all involve local "forging-bending" composite forming of the component. During the progressive local forging and bending forming process, the shape of the component is relatively stable, and no significant forming defects such as through-rebar and deformation instability occur. By comparing the equivalent strain distribution of the component after different loading steps, it can be found that the equivalent strain distribution of the component after each loading step has good consistency, and the deformation uniformity of the component is high. The above results fully demonstrate that the progressive local forging and bending forming has good stability and reliability.

[0056] The present invention adopts a method of progressive loading and bending from front to back in order to reduce the forming load of the component and avoid filling defects of the U-shaped connector. Since the component is only partially placed in the mold structure during the progressive local forging and bending forming process proposed by the present invention, the overall length of the mold is much smaller than the length of the component. Taking a component length of about 1000 mm as an example, the length of the progressive local forging and bending forming mold is about 1 / 3 of the component length. If the component length is further increased, the length of the progressive local forging and bending forming mold will remain unchanged. Therefore, the mold structure of progressive local forging and bending forming has the advantage of not being limited by the size of the component, and truly realizes the ability to prepare large and complex components with small-size molds. During the forming process, the front hydraulic cylinder 4 and the rear hydraulic cylinder 7 provide a blanking force through the front blanking punch 3 and the rear blanking punch 8, which limits the lateral flow of the material and avoids the occurrence of rib-penetration defects. The use of inner bending rollers 9 and outer bending rollers 10 solves the problems of large bending forming force of the component and large bending mold structure, and realizes local progressive bending of the U-shaped connector. At the same time, the inner bending rollers 9 and outer bending rollers 10 can provide axial constraints, limit the axial deformation of the component, and solve the deformation instability problem caused by uneven deformation inside and outside the component during the bending process.

[0057] Compared with the existing technology, the present invention divides the overall / local forging and overall stretch-bending processes into multiple local closed forging-bending forming steps, greatly reducing the overall mold size and manufacturing cycle, and realizing the ability of small-tonnage presses and overall small-specification molds to prepare U-shaped connectors in a short process, significantly reducing the production cost of components and improving the manufacturing efficiency of components, and avoiding the problem of multiple heating of billets between multiple processes; first, this process solves the problems of lateral flow of materials and local warping in the local forging forming process by setting front and rear pressure punches; secondly, this process solves the problems of deformation instability caused by uneven deformation of the inner and outer sides of the components during local bending by setting I-shaped inner and outer bending rollers; the above inventions significantly improve the forming performance, forming accuracy and manufacturing efficiency of U-shaped connectors.

[0058] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principles and purpose of the present invention. The scope of protection of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. All implementation schemes within its scope shall be subject to the constraints of the present invention.

Claims

1. A U-shaped connector progressive local forging and bending forming die, characterized in that: include: A die, a front edge-holding punch, a forming punch, a rear edge-holding punch sequentially arranged inside the die, and a bending control device arranged at the end of the die, wherein the upper die plate drives the front edge-holding punch and the rear edge-holding punch through the front and rear hydraulic cylinders respectively and drives the forming punch to press down, and the blank is input from one side of the head end of the die and intermittently output to the bending control device at the end; The bending control device comprises: a rotating base, a pair of main control arms arranged thereon, corresponding auxiliary control arms connected to the main control arms, and an inner bending roller and an outer bending roller respectively arranged vertically between the pair of main control arms and the auxiliary control arms; The inner bending roller cooperates with the upper main control arm and the lower main control arm through the shaft sleeve structure, and the outer bending roller cooperates with the upper auxiliary control arm and the lower auxiliary control arm through the shaft sleeve structure; The inner bending roller and the outer bending roller revolve around the rotating base, and the revolving radius of the inner bending roller and the outer bending roller is adjusted by the rotating base according to the curvature radius of the U-shaped connector to achieve the bending forming of the U-shaped connector; The inner bending roller and the outer bending roller both adopt an I-section shaft sleeve structure. The semi-closed shape of the combination of the two matches the outer contour of the U-shaped connector. The spacing between the inner bending roller and the outer bending roller is determined by the length of the upper auxiliary control arm and the lower auxiliary control arm, and both can rotate around their respective central axes.

2. The U-shaped connector progressive partial forging and bending forming die according to claim 1, characterized in that: The strokes of the front hydraulic cylinder and the rear hydraulic cylinder are greater than or equal to the pressing amount of a single blank; there is a height difference between the bottom of the front pressing punch and the bottom of the rear pressing punch, and the height difference is equal to the pressing amount of a single blank.

3. The U-shaped connector progressive partial forging and bending forming die according to claim 1, characterized in that: The working surfaces of the front edge-pressing punch, the forming punch and the rear edge-pressing punch are the same; the forming punch is located between the front edge-pressing punch and the rear edge-pressing punch, and there is a gap between adjacent dies.

4. The U-shaped connector progressive partial forging and bending forming die according to claim 1, characterized in that: A feeding device is provided on the front side of the die to realize horizontal quantitative movement of the blank, and the feeding distance is the spacing between adjacent web reinforcement ribs of the U-shaped connector.

5. A method for progressive local forging and bending of a U-shaped connector based on the die of claim 4, characterized in that: include: Step 1: Clamp the end of the blank away from the die through the feeding device and push the blank through the input end of the die to the bottom of the forming punch. Start the press and run it downward through the upper die plate until the front edge pressing punch contacts the blank. Step 2: The press continues to move downward until the forming punch contacts the blank. During this process, the front hydraulic cylinder is pushed back and the front blank holding punch continuously outputs blank holding force. Step 3: The press moves downward again, and the forming punch partially loads the blank to complete the first step of forming the blank. The front hydraulic cylinder continues to push back, and the front blank holding punch continues to output the blank holding force. Step 4: The press returns and the front hydraulic cylinder pushes out. After the press returns, the feeding device starts and the blank is quantitatively moved to the next area to be deformed. The blank movement distance is determined by the spacing between the adjacent web reinforcement ribs of the U-shaped connector. Step 5. After the feeding is completed, the press moves downward again, and the front edge-holding punch contacts the blank again due to the downward action of the press, while the rear edge-holding punch contacts the formed area; the press continues to move downward until the forming punch contacts the blank. During this process, the front hydraulic cylinder and the rear hydraulic cylinder continue to push back, and the front edge-holding punch and the rear edge-holding punch continue to apply a blanking force to the undeformed area and the deformed area of ​​the blank respectively; the press continues to move downward, and the forming punch locally loads the blank, causing the material to deform, completing the second step of forming; Step 6: The press returns, and the front hydraulic cylinder and the rear hydraulic cylinder are pushed out; after the press returns, the feeding device is started, and the blank is quantitatively moved to the next area to be deformed; Step 7: The press moves downward, and the front and rear pressing punches respectively apply a pressing force to the undeformed area and the formed area of ​​the U-shaped connector under the action of the front and rear hydraulic cylinders; the press continues to move downward, and the forming punch approaches the blank to form the lower blank. During this process or after the forming punch completes the blank forming, the bending control device is turned on, and the inner bending roller and the outer bending roller bend the U-shaped connector under the action of the bending control device; Step 8: The press returns, the front hydraulic cylinder and the rear hydraulic cylinder are pushed out, and the inner bending roller and the outer bending roller are controlled by the bending control device to return to their original positions; after the press returns, the feeding device is started, and the blank is quantitatively moved to the next area to be deformed; Step 9: Repeat steps 7 and 8 until all the ribs of the U-shaped connector are formed and the U-shaped connector is bent.

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