Thinning drawing die capable of improving thickness uniformity of hole wall

Abstract

The invention discloses a thinning drawing die capable of improving hole wall thickness uniformity, which comprises an upper die holder, a lower die holder, an upper backing plate, an ejector rod fixing plate and a female die sleeve fixing plate, the upper backing plate, the ejector rod fixing plate and the female die sleeve fixing plate are sequentially stacked and fixed on the upper die holder, and a thinning female die sleeve is arranged on the female die sleeve fixing plate; a thinning male die is fixedly arranged on the lower die base. The thinning male die comprises a solid cylinder part and a variable end located on the cylinder part, the diameter of the variable end is gradually decreased from the end, in butt joint with the cylinder part, of the variable end to the tail end, and an inverted-cone-shaped counter bore is formed in the end of the variable end. A group of separation seams arranged along the axis direction of the thinning male die are uniformly distributed on the side wall of the variable end head, and the variable end head is separated into a plurality of mutually independent thinning stretching sheets by the separation seams; the ejector rod fixing plate is provided with an ejector rod for opening the variable end, and the end of the ejector rod is provided with a frustum matched with the counter bore. The internal uniformity of the fin holes can be improved, and the height of the fin holes is increased.

Description

Technical Field

[0001] The invention relates to the technical field of fin processing, in particular to a thinning and stretching die for improving the uniformity of hole wall thickness. Background Art

[0002] Radiators and heat exchangers are mainly composed of fins and copper tubes inserted on the fins. Multiple fins are stacked and placed. The spacing between fins is determined by the height of the fin holes. The copper tubes are inserted into the fin holes and fixed by expansion by a tube expander. The forming of the fin holes is sequentially processed through multiple drawing, punching and flanging processes, and then the height of the fin holes is increased by thinning and stretching. The higher the fin holes, the greater the spacing between adjacent fins, the fewer fins are required for each radiator or heat exchanger, and the lower the cost. In the drawing and punching and flanging processes, both the drawing punch and the punching and flanging punch start to stretch from the bottom of the fin hole, squeezing the material upward step by step. Therefore, the inner wall of the entire hole is a pleated structure of varying thickness.

[0003] The existing thinning and stretching process still uses a cylindrical solid punch and die. The solid punch enters the die and starts to stretch the fin hole, that is, it still thins from the bottom of the fin hole upwards, which can easily cause the local material to be too thin, resulting in weakened strength or even cracking. The stretching height is affected by the thickness of the thinnest area, and the stretching amount is limited. Moreover, the uniformity of the inner wall thickness of the stretched fin hole cannot be improved, and it is still a pleated structure with uneven thickness. When the fin hole is matched with the copper tube, the fit is low, so the expansion force is low, which not only affects the reliability of the assembly, but also, due to the low fit, the heat exchange efficiency between the copper tube and the fin is low, and the heat dissipation effect is poor.

[0004] In addition, in mold processing, the processing and assembly accuracy of the thinning die and the thinning punch is particularly high to ensure the consistency of the center of the thinning punch and the thinning die. The thinning die or the thinning punch of the existing mold structure cannot be adjusted and moved, that is, it cannot achieve automatic centering in fin processing according to the situation of the other party. When the thinning die and the thinning punch are not concentric, it acts on the fin hole, which is easy to cause the fin hole to have a height difference, or even a hole or rotten material (the fin hole is smashed). Therefore, whether from the stability of fin processing or the height and uniformity of the fin hole, the existing mold has certain defects. Summary of the invention

[0005] The purpose of the present invention is to provide a thinning and stretching die for improving the uniformity of hole wall thickness, so as to solve the problems that the fin holes formed by the existing die structure have low height, poor inner wall uniformity and easy breakage.

[0006] The technical solution adopted by the present invention to solve its technical problems is: a thinning stretching die for improving the uniformity of hole wall thickness, comprising an upper die base and a lower die base, an upper pad, a push rod fixing plate and a die sleeve fixing plate which are sequentially stacked and fixed on the upper die base, and a thinning die sleeve fixing plate is provided on the die sleeve fixing plate; a thinning punch is fixedly provided on the lower die base; the thinning punch comprises a solid cylindrical portion and a variable end head located on the cylindrical portion, the diameter of the variable end head gradually decreases from the end connected to the cylindrical portion to the end, an inverted cone-shaped countersunk hole is provided at the end of the variable end head, and a group of thinning holes along the thinning punch are evenly distributed on the side wall of the variable end head. A separation slit is arranged in the axial direction, and the separation slit separates the variable end into a plurality of independent thinning and stretching sheets; a push rod is arranged on the push rod fixing plate to open the variable end, and a frustum is arranged at the end of the push rod to match the countersunk hole; when the frustum is in place with the countersunk hole, the variable end is fully opened so that the outer diameter of the variable end is consistent and the same as the cylindrical part; when the fin hole is thinned and formed, the variable end is first opened, and the inner wall of the fin hole is squeezed during the opening process to flatten the inner wall of the fin hole, and then the opened variable end moves upward relative to the fin hole, squeezing the fin hole material upward to achieve thinning and stretching of the fin hole wall.

[0007] In order to facilitate adjustment of the position where the thinning punch contacts the inner wall of the fin hole first, a punch fixing plate for fixing the thinning punch is provided on the lower die seat; a height adjustment device for adjusting the height of the punch fixing plate is provided below the punch fixing plate.

[0008] Furthermore, the height adjustment device includes a lower inclined wedge arranged on the lower die base and an upper inclined wedge cooperating with the lower inclined wedge, and the punch fixing plate is supported on the upper inclined wedge.

[0009] Furthermore, a push rod spring for applying pressure to the push rod is arranged above the fixed end of the push rod. A pressure plate is arranged on the thinning punch, a stripper plate is arranged floatingly above the pressure plate, a stripper spring is arranged between the stripper plate and the lower die seat, and the spring force of the push rod spring is greater than the spring force of the stripper spring. A pressure rod is also arranged on the upper die seat, a pressure rod spring is arranged between the pressure rod and the upper die seat, and under the action of the pressure rod spring, the front end of the pressure rod extends out of the fixed plate of the die sleeve; the spring force of the pressure rod spring is greater than the spring force of the push rod spring.

[0010] Beneficial effects of the present invention: The present invention cooperates with the thinning punch and the push rod. The thinning punch first stretches and squeezes the inner wall of the fin hole under the action of the push rod to flatten the inner wall of the fin hole, and then stretches and thins the fin hole. Therefore, compared with the existing structure, the inner wall of the fin hole obtained by the present invention is more uniform and the stretching height is higher, so the performance of the fin can be significantly improved. When the cone of the push rod enters the countersunk hole, under the action of the countersunk hole, the push rod drives the thinning die sleeve to move together, so that the push rod and the thinning die sleeve and the thinning punch are automatically aligned, ensuring the concentric setting with the fin hole, so that when the fin hole is stretched and thinned, there will be no situation where the stretching amount on one side is large and the stretching amount on the other side is small, avoiding the problem of height difference in the fin hole, or even broken holes and rotten materials (fin holes are smashed). The thinning punch can also adjust the initial height through the height adjustment device, thereby adjusting the position where the thinning punch first contacts the inner wall of the fin hole. Therefore, the height of the thinning punch can be adjusted according to the thickness of the inner wall of the fin hole before thinning and stretching, so that the thinning punch first contacts the thickest position of the inner wall of the fin hole for leveling, thereby meeting the processing requirements of fins of different heights.

[0011] The present invention will be described in more detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the mold of the present invention when it is in an open state.

[0013] Figure 2 It is a structural schematic diagram of the working state 1 of the mold of the present invention.

[0014] Figure 3 for Figure 2 A partial enlarged view.

[0015] Figure 4 It is a structural schematic diagram of the second working state of the mold of the present invention.

[0016] Figure 5 for Figure 4 A partial enlarged view of B.

[0017] Figure 6 A schematic structural diagram of the mold working state three of the present invention.

[0018] Figure 7 for Figure 6 A partial enlarged view of C.

[0019] Figure 8 It is a structural schematic diagram of the third working state of the mold of the present invention.

[0020] Fig. 9 for Figure 8 A partial enlarged view of D.

[0021] Fig.10 It is a schematic diagram of the partial three-dimensional structure of the thinning punch in the present invention. DETAILED DESCRIPTION

[0022] Examples, such as Figures 1 to 10 As shown, a thinning and stretching die for improving the uniformity of hole wall thickness is used to thin and stretch the fin hole 100 after fin flanging, thereby improving the uniformity of the wall thickness of the fin hole 100 and then increasing the stretching height of the fin hole 100. The thinning and stretching die for improving the uniformity of hole wall thickness comprises an upper die assembly and a lower die assembly that cooperate with each other, and the upper die assembly comprises an upper die seat 1, an upper pad 3, a push rod fixing plate 4 and a die sleeve fixing plate 5 that are sequentially stacked and fixed on the upper die seat 1. A thinning die sleeve 51 is fixedly arranged on the die sleeve fixing plate 5. When processing parts, the mounting hole on the die sleeve fixing plate 5 for mounting the thinning die sleeve 51 is clearance-matched with the thinning die sleeve 51, that is, when processing parts, the diameter of the mounting hole is larger than the diameter of the thinning die sleeve 51. Therefore, when the thinning die sleeve 51 is mounted on the die sleeve fixing plate 5, a certain amount of displacement can be achieved. The lower die assembly includes a lower die base 2, a height adjustment device 10 installed on the lower die base 2, a punch fixing plate 9 arranged on the height adjustment device 10, a thinning punch 6 fixedly installed on the punch fixing plate 9, and a pressing plate 12 for pressing the thinning punch 6 is arranged on the punch fixing plate 9. A stripper plate 13 is also floatingly arranged above the pressing plate 12. The specific matching structure of the stripper plate 13 is as follows: a stripper spring 14 for pushing the stripper plate 13 upward is arranged between the stripper plate 13 and the lower die base 2, and a limit block 15 for limiting the upper travel of the stripper plate 13 is also fixedly arranged on the lower die base 2, and the limit block 15 is a 7-shaped structure.

[0023] The thinning punch 6 includes a solid cylindrical portion 61 and a variable end 62 located on the cylindrical portion 61. The diameter of the variable end 62 gradually decreases from the end connected to the cylindrical portion 61 to the end, and the taper R of the variable end 62 is 0.2-0.5°. An inverted cone-shaped countersunk hole 621 is provided at the end of the variable end 62, and a group of separation slits 622 arranged along the axial direction of the thinning punch 6 are evenly distributed on the side wall of the variable end 62. The separation slits 622 separate the variable end 62 into a plurality of independent thinning stretching sheets 623. The push rod fixing plate 4 is provided with a push rod 7 for opening the variable end 62. The push rod 7 passes through the thinning die sleeve 51 and is precisely matched with the thinning die sleeve 51, that is, there is no offset margin between the two. The push rod 7 drives the thinning die sleeve 51 to move together. The end of the push rod 7 is provided with a cone 71 adapted to the countersunk hole 621, and a push rod spring 8 for applying pressure to the push rod 7 is provided above the fixed end of the push rod 7, and an upper pressure plate 11 is provided at the other end of the push rod spring 8, and the upper pressure plate 11 is fixedly mounted on the upper die seat 1. When the cone 71 is in place with the countersunk hole 621, the variable end 62 is fully opened so that the outer diameter of the variable end 62 is consistent and the same as the cylindrical part 61. In order to control the order of matching of each component and ensure that after the thinning punch 6 enters the fin hole 100, the variable end 62 is first opened, the inner wall of the fin hole 100 is pressed, and then the fin hole 100 is stretched by the upward movement of the thinning punch 6, the spring force of the push rod spring 8 is greater than the spring force of the unloading spring 14. A pressure rod 18 is also provided on the upper die base 1, and a pressure rod spring 19 is provided between the pressure rod 18 and the upper die base 1. Under the action of the pressure rod spring 19, the front end of the pressure rod 18 extends out of the die sleeve fixing plate 5; the spring force of the pressure rod spring 19 is greater than the spring force of the push rod spring 8.

[0024] The height adjustment device 10 includes a lower inclined wedge 101 provided on the lower die base 2 and an upper inclined wedge 102 cooperating with the lower inclined wedge 102, and the punch fixing plate 9 is supported on the upper inclined wedge 102. A screw 16 is also provided to push the lower inclined wedge 101 to move, and a digital display device 17 is installed on the screw 16 to accurately read the advancement distance of the screw 16. The height adjustment device 10 can be used to adjust the initial contact position of the variable end 62 of the thinning punch 6 with the inner wall of the fin hole 100, so that the position with the thickest wall thickness of the fin hole 100 is first contacted and pressed, and then stretched, thereby increasing the stretched height of the fin hole 100.

[0025] The specific movement process is as follows: Figure 1As shown, in the initial state, the mold is opened, the push rod 7 is at the lowest point under the action of the push rod spring 8, and the pressure rod 18 is at the lowest point under the action of the pressure rod spring 19, so that the end of the pressure rod 18 extends out of the die sleeve fixing plate 5, and the stripper plate 13 is pushed upward under the action of the stripper spring 14, and the stripper plate 13 is at the upper limit position. When the upper mold assembly moves downward, the pressure rod 18 first contacts the stripper plate 13. At this time, the cone 71 begins to enter the counterbore 621 but does not contact the counterbore 621. At the same time, the thinning punch 6 does not enter the fin hole 100, as shown in FIG. Figure 2 , Figure 3 shown.

[0026] The upper mold assembly continues to move downward. Since the spring force of the pressure rod spring 19 is greater than the spring force of the discharge spring 14, the discharge plate 13 is pressed downward by the pressure rod 18 until the discharge plate 13 is close to the pressure plate 12. At this time, the outer wall of the cone 71 is in contact with the inner wall of the countersunk hole 621 but is not subjected to force. The thinning die sleeve 51 is sleeved outside the fin hole 100, and the thinning punch 6 enters the fin hole 100. During the downward movement, the push rod 7 is continuously adjusted by the countersunk hole 621 to adjust the position of the push rod 7 and the thinning die sleeve 51, so as to realize the automatic centering of the thinning die sleeve 51 and the thinning punch 6. At the same time, the push rod spring 8 is in a critical state at this time. If force is continued to be applied, it will shrink and deform. Figure 4 , Figure 5 shown.

[0027] The upper mold assembly continues to move downward. When the spring force applied to the push rod spring 8 is greater than the critical value, the push rod spring 8 contracts inward, and the thinning punch 6 moves upward relative to the fin hole 100. When the outer wall of the variable end 62 of the thinning punch 6 contacts the inner wall of the fin hole 100, the spring force of the push rod spring 8 acting on the push rod 7 is less than the force required to open the variable end 62. The position where the variable end 62 first contacts the inner wall of the fin hole 100 is the position where the wall thickness of the fin hole 100 is the thickest, so it is convenient to first level the position where the wall thickness is the thickest. In order to meet the different positions of the thickest part of the inner wall of the fin hole 100 when processing different fins, the initial height of the thinning punch 6 can be adjusted by the height adjustment device 10 to ensure that the variable end 62 contacts the thickest part of the fin hole 100 first. Figure 6 , Figure 7 shown.

[0028] The upper mold assembly continues to move downward, and the spring force of the ejector spring 8 on the ejector 7 is greater than the force required to open the variable end 62. The ejector 7 opens the variable end 62 outward. As the force required to open the variable end 62 increases, the ejector spring 8 also continues to contract upward until the ejector 7 completely opens the variable end 62, and the ejector spring 8 is compressed to the upper vertex. Figure 5As shown, the variable end 62 continuously squeezes the inner wall of the fin hole 100 during the process of being stretched outward, so that the material of the inner wall of the fin hole 100 is transferred upward during the squeezing, and the inner wall of the fin hole is pressed and straightened.

[0029] The upper die assembly continues to move downward, overcoming the spring force of the pressure rod spring 19, causing the pressure rod 18 to move upward, completing the closing of the upper die assembly and the lower die assembly. In this process, the thinning punch 6 stretches the hole wall of the fin hole upward to complete the thinning and stretching of the fin hole. Figure 8 , Fig. 9 shown.

[0030] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A thinning and stretching die for improving the uniformity of hole wall thickness, comprising an upper die base (1) and a lower die base (2), an upper pad (3), a push rod fixing plate (4) and a die sleeve fixing plate (5) which are sequentially stacked and fixed on the upper die base (1), characterized in that: The die sleeve fixing plate (5) is provided with a thinning die sleeve (51); the lower die seat (2) is fixedly provided with a thinning punch (6); the thinning punch (6) comprises a solid cylindrical portion (61) and a variable end head (62) located on the cylindrical portion (61); the diameter of the variable end head (62) gradually decreases from the end connected with the cylindrical portion (61) to the end; an inverted cone-shaped countersunk hole (621) is provided at the end of the variable end head (62); and a group of separation slits (622) arranged along the axial direction of the thinning punch (6) are evenly distributed on the side wall of the variable end head (62); the separation slits (622) separate the variable end head (62) into a plurality of independent thinning drawing portions. The extension piece (623) is provided on the push rod fixing plate (4) with a push rod (7) for stretching the variable end head (62), and the end of the push rod (7) is provided with a cone (71) adapted to the countersunk hole (621); when the cone (71) and the countersunk hole (621) are in place, the variable end head (62) is fully stretched so that the outer diameter of the variable end head (62) is consistent and the same as the cylindrical part (61); when the fin hole is thinned and formed, the variable end head (62) is first stretched, and the inner wall of the fin hole is squeezed during the stretching process to flatten the inner wall of the fin hole, and then the stretched variable end head (62) moves upward relative to the fin hole, squeezing the fin hole material upward to achieve thinning and stretching of the fin hole wall.

2. The thinning and stretching die for improving the uniformity of hole wall thickness according to claim 1, characterized in that: The lower die base (2) is provided with a punch fixing plate (9) for fixing the thinning punch (6); and a height adjustment device (10) for adjusting the height of the punch fixing plate (9) is provided below the punch fixing plate (9).

3. The thinning and stretching die for improving the uniformity of hole wall thickness according to claim 2, characterized in that: The height adjustment device (10) comprises a lower inclined wedge (101) arranged on the lower die seat (2) and an upper inclined wedge (102) matched with the lower inclined wedge (102), and the punch fixing plate (9) is supported on the upper inclined wedge (102).

4. The thinning and stretching die for improving the uniformity of hole wall thickness according to claim 1, characterized in that: The mounting hole on the die sleeve fixing plate (5) for mounting the thinned die sleeve (51) is clearance-matched with the thinned die sleeve (51), and after assembly, the thinned die sleeve (51) can move left and right, front and back in the mounting hole of the die sleeve fixing plate (5).

5. The thinning and stretching die for improving the uniformity of hole wall thickness according to claim 1, characterized in that: A push rod spring (8) for applying pressure to the push rod (7) is arranged above the fixed end of the push rod (7).

6. The thinning and stretching die for improving the uniformity of hole wall thickness according to claim 5, characterized in that: A pressure plate (12) is arranged on the thinning punch (6), a discharge plate (13) is floatingly arranged above the pressure plate (12), a discharge spring (14) is arranged between the discharge plate (13) and the lower die seat (2), and the spring force of the ejector spring (8) is greater than the spring force of the discharge spring (14).

7. The thinning and stretching die for improving the uniformity of hole wall thickness according to claim 6, characterized in that: A pressure rod (18) is also provided on the upper die seat (1), and a pressure rod spring (19) is provided between the pressure rod (18) and the upper die seat (1). Under the action of the pressure rod spring (19), the front end of the pressure rod (18) extends out of the die sleeve fixing plate (5); the spring force of the pressure rod spring (19) is greater than the spring force of the push rod spring (8).

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