Punching device for metal sheet reaming test

Abstract

A punching device for a metal sheet chambering test comprises an upper die base, a lower die base, a guide column, a guide sleeve, a reset spring and a limiting column. A central positioning hole is formed in the center of the upper die holder, and a groove is circumferentially formed in the inner wall of the upper part; a central positioning groove is formed in the top center of the lower die holder; the male die positioning ring is arranged in the central positioning hole, and a fixed groove is formed in the upper part of the inner edge of the male die positioning ring along the circumferential direction; the male die is arranged in the male die positioning ring, and a fixed step is arranged on the outer side of the upper part along the circumferential direction; the male die cover is arranged on the bottom face of the male die and connected to the bottom of the groove in the inner wall of the upper portion of the center positioning hole of the upper die base through bolts. The elastic material pressing ring is arranged at a center positioning hole in the bottom face of the upper die base, and the male die penetrates through the elastic material pressing ring; the female die positioning ring is a center positioning groove formed in the center of the top face of the lower die base, and a fixing groove is formed in the lower portion of the inner wall of the female die positioning ring in the circumferential direction; the female die is arranged in the female die positioning ring, and the bottom of the female die abuts against a fixing groove in the lower portion of the inner wall of the female die positioning ring.

Description

Technical Field

[0001] This utility model belongs to the field of metal sheet inspection technology, and in particular relates to a punching device for metal sheet hole enlargement test. Background Technology

[0002] Hole expansion rate is an important performance evaluation index for metal sheet materials used in the automotive industry. For some automotive parts that require flanging and hole expansion, it is very important to correctly evaluate the hole expansion rate of metal sheet. Otherwise, unpredictable cracking defects may occur during the forming process, making it impossible to maintain normal production.

[0003] Before conducting a hole enlargement test on thin metal sheets, punching is required. The initial diameter of the circular hole is 10 mm. The latest national standard for hole enlargement testing, "Test Methods for Hole Enlargement of Thin Metallic Materials (Sheets and Strips)" (GB / T24524-2021), stipulates that the initial circular hole for the hole enlargement test is prepared by mechanical punching using a 10 mm diameter punching die. The inner diameter of the punching die needs to be adjusted according to the thickness of the steel sheet sample. The national standard specifies that the single-sided clearance of the punching is set at 12% of the steel sheet thickness, and the inner diameter of the die is selected in increments of 0.1 mm. Therefore, the problem of needing to change the die according to the thickness of the sample frequently arises during testing. Although the punch is replaced infrequently, after a certain number of punchings, wear will affect the punching quality, so periodic replacement is necessary. This requires the punching device to have a rapid die-changing function and high die-die alignment accuracy after replacement to meet the testing requirements.

[0004] Currently, the punching devices used in laboratory hole expansion tests generally lack the ability to quickly change dies. Changing dies is time-consuming and labor-intensive, and most of the time in the hole expansion test is wasted in the punching process. Although there are punching devices on the market that can quickly change dies, such as turret punch presses or other specially designed automatic devices, the equipment is too large and expensive, making it unsuitable for laboratory use.

[0005] The manual small punching devices commonly used in laboratories often have the problem of being cumbersome to replace the punch and die. Due to reassembly, the accuracy of the punch and die alignment deteriorates and the punching gap becomes uneven, which affects the punching quality and ultimately the detection accuracy of the hole expansion test. Summary of the Invention

[0006] The purpose of this utility model is to provide a punching device for expanding holes in thin metal plates, which overcomes the problems of long replacement cycle, cumbersome operation, and decreased accuracy after assembly of existing punching devices, thereby improving the accuracy and efficiency of expanding hole tests.

[0007] To achieve the above objectives, the solution of this utility model is:

[0008] A punching device for expanding holes in thin metal sheets includes an upper die base, a lower die base, guide posts and their upper guide sleeves connecting the upper and lower die bases on both sides, and return springs and limiting posts inside the return springs disposed on both sides between the upper and lower die bases; wherein...

[0009] The upper mold base is provided with a central positioning hole in the center, and the upper inner wall of the central positioning hole is provided with a groove along the circumference.

[0010] A central positioning groove is provided in the center of the top surface of the lower mold base, which is arranged on the same axis as the central positioning hole of the upper mold base.

[0011] A punch positioning ring is provided in the central positioning hole, and a fixing groove is provided circumferentially on the upper part of the inner edge of the punch positioning ring;

[0012] A punch is disposed in the punch positioning ring. A fixed step is provided on the outer side of the upper part of the punch along the circumferential direction, and is thus fixed to the fixed groove on the punch positioning ring.

[0013] The punch cover is located on the bottom surface of the punch, and its side is connected to the bottom of the groove on the upper inner wall of the center positioning hole of the upper die base by bolts;

[0014] An elastic pressure ring is bolted to the center positioning hole on the bottom surface of the upper die holder, and the punch passes through the elastic pressure ring.

[0015] A die positioning ring is provided in the center positioning groove at the center of the top surface of the lower die base. The die positioning ring is coaxial with the center positioning hole of the upper die base. A fixing groove is provided circumferentially on the lower part of the inner wall of the die positioning ring.

[0016] The die cavity is located inside the die cavity positioning ring, and the bottom of the die cavity abuts against the fixing groove at the lower part of the inner wall of the die cavity positioning ring.

[0017] Preferably, the upper mold base center positioning hole, the punch, and the punch positioning ring are concentric and have a clearance fit, wherein the clearance value between the punch and the punch positioning ring is ≤0.03mm, and the clearance value between the punch positioning ring and the center positioning hole is ≤0.05mm.

[0018] Preferably, the total clearance between the punch, the punch positioning ring, and the center positioning hole of the upper die base is controlled within 0.04 to 0.05 mm.

[0019] Preferably, the die cavity, the die cavity positioning ring, and the lower die base center positioning groove are concentric and have a clearance fit, wherein the clearance between the die cavity and the die cavity positioning ring is ≤0.03mm, and the clearance between the die cavity positioning ring and the center positioning groove is ≤0.05mm.

[0020] Preferably, the total clearance between the die cavity, the die cavity positioning ring, and the lower die base center positioning groove is controlled within 0.04 to 0.05 mm.

[0021] Preferably, the elastic pressure ring is made of rubber or PVC board material.

[0022] In the punching device described in this utility model:

[0023] A central positioning hole is set in the center of the upper die holder. A punch positioning ring is set inside the central positioning hole, and a punch is set inside the punch positioning ring. The three are concentric and have a clearance fit. The clearance between the punch and the punch positioning ring is ≤0.03mm, which can improve the accuracy of alignment. The clearance between the punch positioning ring and the central positioning hole is ≤0.05mm, which can improve the convenience of disassembling and assembling the punch positioning ring. The total clearance of the three is controlled between 0.04 and 0.05mm, which not only achieves precise alignment of the punch, but also facilitates the quick replacement of the punch.

[0024] The upper mold base is equipped with a punch cover. The punch cover, punch positioning ring and punch are all designed to be removed or installed from above, which facilitates the quick installation of the punch.

[0025] The lower die base has a central positioning groove, within which a die positioning ring is installed. The die itself is housed within the die positioning ring. All three are concentric and have a clearance fit. The clearance between the die and the die positioning ring is ≤0.03mm, improving alignment accuracy. The clearance between the die positioning ring and the central positioning groove is ≤0.05mm, enhancing the ease of assembly and disassembly of the die positioning ring. The total clearance should be controlled between 0.04 and 0.05mm to ensure precise punch alignment and facilitate rapid punch replacement. The die positioning ring and the die are designed to be removed or installed from above, facilitating quick die installation.

[0026] Two or more evenly distributed guide pillars and guide sleeves are set between the upper and lower die bases to connect the upper and lower die bases together, which can realize the stable movement of the punch in the vertical direction. Two or more evenly distributed limit pillars and return springs are also set between the upper and lower die bases, which can accurately control the amount of overlap between the punch and the die during punching, and also leave space for sample placement and die changing.

[0027] An elastic pressure (ejection) ring is set on the upper die base, the punch, and the outer ring of the punch positioning ring. It can be made of rubber or similar materials to increase the stability of the sheet during punching and the ejection function of the metal sample after punching.

[0028] The device described in this utility model is an independent design. During punching, it is placed between the movable beam plate and the worktable of the testing machine. The upper die does not need to be connected to the movable beam plate (slider) of the testing machine; the lower die can also be placed directly on the worktable, reducing the cumbersome steps of assembly and connection.

[0029] The beneficial effects of this utility model are:

[0030] This utility model has corresponding positioning holes or positioning grooves and positioning rings for the upper and lower mold bases. Through concentric structure and clearance fit, the assembly of the die and the mold is simple and reliable, and the mold clearance is uniform, which greatly ensures the quality of punching.

[0031] The present invention is designed so that both the concave and convex dies can be removed from directly above, eliminating the need to flip and disassemble the assembled die base, making the replacement of the concave and convex dies very convenient.

[0032] In addition, the device described in this utility model is designed as an independent working mechanism, and the upper and lower die bases do not need to be fixed to the worktable and slider during the punching test.

[0033] This invention overcomes the problems of difficult assembly, uneven quality, and long test cycle in the initial round hole processing of existing hole expansion tests. It can quickly and accurately process the initial round hole for hole expansion and quickly punch out metal sheet samples of different thicknesses that meet the requirements of national standards for hole expansion tests. While improving test efficiency, it also improves the accuracy of hole expansion detection of steel plates. Attached Figure Description

[0034] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model. Detailed Implementation

[0035] See Figure 1 The present invention relates to a punching device for expanding holes in thin metal plates, comprising an upper die base 1, a lower die base 2, guide posts 3 connecting the two sides of the upper die base 1 and the lower die base 2 and their upper guide sleeves 4, and return springs 5 ​​disposed on both sides between the upper die base 1 and the lower die base 2, and limiting posts 6 within the return springs 5; wherein,

[0036] The upper mold base 1 is provided with a central positioning hole 101 in the center, and a groove 102 is provided on the upper inner wall of the central positioning hole 101 along the circumferential direction.

[0037] The lower mold base 2 has a central positioning groove 201 at the center of its top surface, which is coaxial with the central positioning hole 101 of the upper mold base 1.

[0038] A punch positioning ring 7 is disposed in the central positioning hole 101, and a fixing groove 71 is provided circumferentially on the upper part of the inner edge of the punch positioning ring 7;

[0039] A punch 8 is disposed in the punch positioning ring 7. A fixed step 81 is provided on the outer side of the upper part of the punch 8 along the circumferential direction, and is fixed to the fixed groove 71 on the punch positioning ring 7.

[0040] A punch cover 9 is set on the bottom surface of the punch 8, and its side is connected to the bottom of the groove 102 on the upper inner wall of the center positioning hole 101 of the upper die base 1 by bolts.

[0041] The elastic pressure ring 10 is bolted to the center positioning hole 101 on the bottom surface of the upper mold base 1, and the punch 8 passes through the elastic pressure ring 10.

[0042] A die positioning ring 11 is provided in the center positioning groove 201 at the center of the top surface of the lower die base 2. The die positioning ring 11 is coaxial with the center positioning hole 101 of the upper die base 1. A fixing groove 111 is provided circumferentially on the lower part of the inner wall of the die positioning ring 11.

[0043] The die 12 is disposed inside the die positioning ring 11, and the bottom of the die 12 abuts against the fixing groove 111 at the lower part of the inner wall of the die positioning ring 11.

[0044] Preferably, the upper mold base 1 has a concentric structure and clearance fit between the center positioning hole 101, the punch 8 and the punch positioning ring 7, wherein the clearance value between the punch 8 and the punch positioning ring 7 is ≤0.03mm and the clearance value between the punch positioning ring 7 and the center positioning hole 101 is ≤0.05mm.

[0045] Preferably, the total clearance between the punch 8, the punch positioning ring 7, and the center positioning hole 101 of the upper die holder 1 is controlled to be between 0.04 and 0.05 mm.

[0046] Preferably, the die cavity 12, the die cavity positioning ring 11, and the center positioning groove 201 of the lower die base 2 are concentric and have a clearance fit, wherein the clearance value between the die cavity 12 and the die cavity positioning ring 11 is ≤0.03mm, and the clearance value between the die cavity positioning ring 11 and the center positioning groove 201 is ≤0.05mm.

[0047] Preferably, the total clearance between the die cavity 12, the die cavity positioning ring 11, and the center positioning groove 201 of the lower die base 2 is controlled to be between 0.04 and 0.05 mm.

[0048] Preferably, the elastic pressure ring 10 is made of rubber or PVC board material.

[0049] The experimental process for this utility model is as follows:

[0050] 1) Move the punching device onto the test machine workbench 200 and place it in the center of the workbench 200. The upper and lower die bases do not need to be fixed to the test machine.

[0051] 2) Place a steel plate sample 400 on the die positioning ring 11 and center it; make the moving beam plate 100 (slider) of the testing machine move downward, and push the upper die seat 1 to move downward continuously through the beam plate or the pressure head 300 until the upper die seat 1 completely touches the limit post 6 and stops pressing down. The punching process of the steel plate sample 400 is completed by the shear deformation between the die and the punch.

[0052] 3) Lift the movable beam plate 100 (slider) of the testing machine so that the elastic pressure ring 10 is completely separated from the steel plate sample 400 until the upper mold base 1 returns to the starting position and the testing machine stops moving.

[0053] 4) Take out the steel plate sample 400 and check the fracture quality of the round hole. If there are quality defects such as burrs, missing material, collapsed edges, or delamination on the edge of the round hole, the punch needs to be checked and replaced.

[0054] If the punch needs to be replaced during the process, first remove the punch cover, take out the punch positioning ring from the upper die holder, and use tools such as copper rods to remove the existing punch from the punch positioning ring. Check whether the punch has dulled cutting edges or chipped edges. If so, replace it with a new punch and then reassemble it.

Claims

1. A punching device for expanding holes in thin metal sheets, comprising an upper die base, a lower die base, guide posts and their upper guide sleeves connecting the upper die base and the lower die base on both sides, a return spring and a limiting post inside the return spring disposed on both sides between the upper die base and the lower die base; characterized in that, The upper mold base is provided with a central positioning hole in the center, and the upper inner wall of the central positioning hole is provided with a groove along the circumference. A central positioning groove is provided in the center of the top surface of the lower mold base, which is arranged on the same axis as the central positioning hole of the upper mold base. A punch positioning ring is provided in the central positioning hole, and a fixing groove is provided circumferentially on the upper part of the inner edge of the punch positioning ring; A punch is disposed in the punch positioning ring. A fixed step is provided on the outer side of the upper part of the punch along the circumferential direction, and is thus fixed to the fixed groove on the punch positioning ring. The punch cover is located on the bottom surface of the punch, and its side is connected to the bottom of the groove on the upper inner wall of the center positioning hole of the upper die base by bolts; An elastic pressure ring is bolted to the center positioning hole on the bottom surface of the upper die holder, and the punch passes through the elastic pressure ring. A die positioning ring is provided in the center positioning groove at the center of the top surface of the lower die base. The die positioning ring is coaxial with the center positioning hole of the upper die base. A fixing groove is provided circumferentially on the lower part of the inner wall of the die positioning ring. The die cavity is located inside the die cavity positioning ring, and the bottom of the die cavity abuts against the fixing groove at the lower part of the inner wall of the die cavity positioning ring.

2. The punching device for expanding holes in thin metal plates as described in claim 1, characterized in that, The upper mold base center positioning hole, the punch, and the punch positioning ring are concentric and have a clearance fit, wherein the clearance value between the punch and the punch positioning ring is ≤0.03mm, and the clearance value between the punch positioning ring and the center positioning hole is ≤0.05mm.

3. The punching device for expanding holes in thin metal plates as described in claim 1 or 2, characterized in that, The total clearance between the punch, the punch positioning ring, and the center positioning hole of the upper die base is controlled to be between 0.04 and 0.05 mm.

4. The punching device for expanding holes in thin metal plates as described in claim 1, characterized in that, The die cavity, the die cavity positioning ring, and the lower die base center positioning groove are concentric and have a clearance fit. The clearance between the die cavity and the die cavity positioning ring is ≤0.03mm, and the clearance between the die cavity positioning ring and the center positioning groove is ≤0.05mm.

5. The punching device for expanding holes in thin metal plates as described in claim 1 or 4, characterized in that, The total clearance between the die, the die positioning ring, and the lower die base center positioning groove is controlled within 0.04 to 0.05 mm.

6. The punching device for expanding holes in thin metal plates as described in claim 1, characterized in that, The elastic pressure ring is made of rubber or PVC board.

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