Fine blanking process for reducing cracking of a punched end face

Abstract

This application relates to the field of stamping technology, and in particular to a fine stamping process for reducing cracking on the end face of a hole, comprising the following steps: S1, pre-punching a vertical cutting hole on a horizontally placed metal plate; simultaneously pressing a first-press straight chamfer on the metal plate relative to the top of the cutting hole, and simultaneously pressing a first-press rounded chamfer on the metal plate relative to the bottom of the cutting hole; S2, the top of the metal plate relative to the cutting hole is deformed downward under pressure, causing a downward indentation to form at the edge of the cutting hole; S3, the edge of the cutting hole continues to deform downward under force, causing the edge of the cutting hole to fold downward to a vertical position, and the punching surface of the cutting hole folds to form a lower end face; S4, applying an upward extrusion force to the lower end face of the hole to flatten it. This application has the advantage of reducing the possibility of cracks forming on the workpiece during the hole-making process.

Description

Technical Field

[0001] This application relates to the field of stamping technology, and in particular to a fine stamping process for reducing cracking at the end face of the bore. Background Technology

[0002] Flipping refers to a processing technique that flips the edge of a hole into a vertical edge.

[0003] A workpiece flanging process is disclosed in the related technology, referring to Figure 1 The process includes step a: pre-punching vertical cutting holes on a horizontally placed metal plate; step b: the top of the metal plate is deformed downwards relative to the cutting hole, causing a downward indentation to form at the edge of the cutting hole, at which point the thickness of the cutting surface of the cutting hole is 0.8 times the thickness of the metal plate; step c: the edge of the cutting hole continues to deform downwards under force, causing the edge of the cutting hole to fold downwards to a vertical position, and the cutting surface of the cutting hole folds to form a lower end face; step d: applying an upward compressive force to the lower end face of the folded hole to flatten the lower end face.

[0004] Due to the different thicknesses of the sheet metal used in different applications, such as the thickness of automotive seat adjustment parts which ranges from approximately 4mm to 6mm, analysis of the flanging process revealed that due to the relatively large thickness of the sheet metal, a large number of cracks are generated during the process of folding the punched surface to form the lower end face, resulting in significant defects. Summary of the Invention

[0005] In order to improve the problem of cracks in the process of turning holes in thick plates, this application provides a fine stamping process to reduce cracking on the end face of the hole.

[0006] The fine blanking process for reducing cracking at the end face of the borehole provided in this application adopts the following technical solution:

[0007] A fine blanking process for reducing cracking at the end face of a punched hole includes the following steps: S1, a vertical punching hole is pre-punched on a horizontally placed metal plate, and a first-press straight chamfer is simultaneously pressed on the metal plate relative to the top of the punching hole, and a first-press rounded chamfer is simultaneously pressed on the metal plate relative to the bottom of the punching hole; S2, the top of the metal plate relative to the punching hole is deformed downward under pressure, causing a downward indentation to form at the edge of the punching hole; S3, the edge of the punching hole continues to deform downward under force, causing the edge of the punching hole to fold downward to a vertical position, and the punching surface of the punching hole folds to form the lower end face; S4, an upward extrusion force is applied to the lower end face of the punched hole to flatten the lower end face.

[0008] By adopting the above technical solution, while punching out the cutting hole, the first pressing straight chamfer and the first pressing rounded chamfer are pressed out. In this way, the structure of the metal plate near the edge of the cutting hole will be pressed more compactly, reducing the possibility of cracks appearing in this part during the hole turning process.

[0009] Optionally, in step S1, the chamfer depth of the first straight chamfer is greater than the chamfer depth of the first rounded chamfer.

[0010] By adopting the above technical solution, since the metal plate will expand relative to the punching surface of the cut hole during the turning process, and the lower the height of the cut hole, the greater the expansion, the part of the metal plate with a more compact structure under pressure is located at the lower position of the cut hole, which further reduces the possibility of the punching surface of the cut hole cracking during the turning process.

[0011] Optionally, in step S1, a transition arc surface is simultaneously pressed at the junction of the metal plate relative to the initial pressing straight chamfer and the punching surface.

[0012] By adopting the above technical solution, the transition arc surface makes the junction between the first pressing straight chamfer and the punching surface smoother, which facilitates the subsequent further extrusion of both.

[0013] Optionally, in step S1, a step is simultaneously pressed at the junction of the metal plate relative to the initial pressing arc chamfer and the punching surface.

[0014] By adopting the above technical solution, when the metal plate is squeezed relative to the punching hole, the squeezing direction is not directly towards the punching tool, so it is not easy to damage the tool, and it also pre-presses for further squeezing, reducing the problem that it is difficult to squeeze directly into place in one go.

[0015] Optionally, after step S1, the height of the punched surface is 0.3-0.35 times the thickness of the metal plate.

[0016] By adopting the above technical solution, the height of the punching surface is reduced, thereby minimizing the area prone to cracking.

[0017] Optionally, after step S2, the height of the punched surface is 0.15-0.2 times the thickness of the metal plate.

[0018] By adopting the above technical solution, the height of the punching surface can be further reduced, and the area prone to cracking can be further reduced.

[0019] Optionally, in step S2, the positions of the metal plate relative to the first pressing straight chamfer and the transition arc surface, the first pressing arc chamfer and the step are all pressed into pre-flipped arc chamfers.

[0020] By adopting the above technical solution, the first pressing straight chamfer and transition arc surface, the first pressing arc chamfer and step are combined and pressed into two pre-flipped arc chamfers, so that the entire position of the metal plate relative to the punching hole is smoother, which is conducive to improving the flipping effect.

[0021] Optionally, in step S2, the pre-turned chamfer of the metal plate relative to the top of the punch hole is S-shaped.

[0022] By adopting the above technical solution, the S-shaped pre-turned rounded chamfer improves the stress distribution and stability of this part under compressive deformation.

[0023] In summary, this application includes at least one of the following beneficial technical effects:

[0024] 1. While punching out the cutting hole, press out the first pressing straight chamfer and the first pressing rounded chamfer. In this way, the structure of the metal plate near the edge of the cutting hole will be pressed more compactly, reducing the possibility of cracks appearing in this part during the turning process.

[0025] 2. During the flanging process, the metal plate expands relative to the punched surface of the cut hole, and the lower the height of the cut hole, the greater the expansion. Therefore, the part of the metal plate with a more compact structure under pressure is placed at the lower position of the cut hole, which further reduces the possibility of the punched surface of the cut hole cracking during the flanging process. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of the prior art.

[0027] Figure 2 This is a cross-sectional view of an embodiment of this application.

[0028] Explanation of reference numerals in the attached drawings: 1. Metal plate; 2. Cutting and punching hole; 3. First pressing straight chamfer; 4. First pressing rounded chamfer; 5. Transition rounded surface; 6. Step; 7. Pre-turned rounded chamfer. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 2 This application will be described in further detail.

[0030] This application discloses a fine stamping process to reduce cracking on the end face of the borehole.

[0031] Reference Figure 2 The fine blanking process to reduce cracking at the end face of the bore includes the following steps:

[0032] S1. A vertical cutting hole 2 is pre-punched on a horizontally placed metal plate 1. A first-press straight chamfer 3 is simultaneously pressed on the metal plate 1 at the top position relative to the cutting hole 2, and a first-press rounded chamfer 4 is simultaneously pressed on the metal plate 1 at the bottom position relative to the cutting hole 2. After this process, the height of the cutting surface of the cutting hole 2 is 0.3-0.35 times the thickness of the metal plate 1.

[0033] S2. The top of the metal plate 1 is deformed downwards relative to the punch hole 2, causing a depression to form at the edge of the punch hole 2. After this process, the height of the punched surface of the punch hole 2 is 0.15-0.2 times the thickness of the metal plate 1.

[0034] S3. The edge of the punch hole 2 continues to deform downward under the force, causing the edge of the punch hole 2 to fold downward to vertical, and the punching surface of the punch hole 2 folds to form the lower end face.

[0035] S4. Apply an upward pressing force to the lower end face of the hole to flatten it.

[0036] Reference Figure 2 While punching out the cutting hole 2, the first pressing straight chamfer 3 and the first pressing rounded chamfer 4 are pressed out. In this way, the structure of the metal plate 1 near the edge of the cutting hole 2 will be pressed more compactly, reducing the possibility of cracks appearing in this part during the hole turning process.

[0037] In addition, by reducing the height of the punching surface of the punch hole 2, the area prone to cracking is reduced, further reducing the possibility of cracks occurring during the hole turning process.

[0038] Reference Figure 2 In step S1, the chamfer depth of the first straight chamfer 3 is greater than the chamfer depth of the first circular chamfer 4, so that the part of the metal plate 1 that is pressed and becomes compact is biased towards the bottom of the punch hole 2, thereby increasing the possibility that the part will expand greatly without cracking during the hole turning process.

[0039] Reference Figure 2 In step S1, the metal plate 1 is simultaneously pressed with a transition arc surface 5 at the junction of the first pressing straight chamfer 3 and the punching surface. The transition arc surface 5 makes the junction of the two surfaces smoother, thereby reducing the possibility of protruding edges appearing on the punching surface of the punching hole 2 during the subsequent pressing process.

[0040] Reference Figure 2 In step S1, a step 6 is pressed simultaneously at the junction of the metal plate 1 with the first pressing arc chamfer 4 and the punching surface. The pressing of the step 6 causes the part of the metal that becomes compacted during the pre-punching process to spread away from the punching hole 2, leaving room for further extrusion.

[0041] Reference Figure 2 In step S2, the positions of the metal plate 1 relative to the first pressing straight chamfer 3, the transition arc surface 5, the first pressing arc chamfer 4, and the step 6 are all pressed into pre-flipped arc chamfers 7. The first pressing straight chamfer 3, the transition arc surface 5, the first pressing arc chamfer 4, and the step 6 are combined and pressed into two pre-flipped arc chamfers 7, so that the entire position of the metal plate 1 relative to the punching hole 2 is smoother, which is beneficial to improving the hole flipping effect.

[0042] Reference Figure 2 In step S2, the pre-turned rounded chamfer 7 of the metal plate 1 relative to the top of the punch hole 2 is S-shaped; the S-shaped pre-turned rounded chamfer 7 improves the stress distribution of this part when it is subjected to compressive deformation, making it more balanced and stable.

[0043] Reference Figure 2 The fine blanking process of this application is applicable to the hole-making process of thick plates, especially to the hole-making process of an automotive seat adjustment component. The plate thickness of the component is 4.1mm, the height of the punched surface after step S1 is 1.33mm, and the height of the punched surface after step S1 is between 0.6mm and 0.8mm.

[0044] The implementation principle of a fine blanking process for reducing cracking at the end face of a punched hole according to an embodiment of this application is as follows: S1. A vertical punching hole 2 is pre-punched on a horizontally placed metal plate 1. A first-press straight chamfer 3 is simultaneously pressed on the top position of the metal plate 1 relative to the punching hole 2, and a first-press rounded chamfer 4 is simultaneously pressed on the bottom position of the metal plate 1 relative to the punching hole 2. After this process, the height of the punched surface of the punching hole 2 is 0.3-0.35 times the thickness of the metal plate 1. S2. The top position of the metal plate 1 relative to the punching hole 2 is deformed downward under pressure, causing the edge of the punching hole 2 to form a downward indentation. After this process, the height of the punched surface of the punching hole 2 is 0.15-0.2 times the thickness of the metal plate 1. S3. The edge of the punching hole 2 continues to deform downward under force, causing the edge of the punching hole 2 to fold downward to a vertical position, and the punched surface of the punching hole 2 folds to form the lower end face. S4. An upward pressing force is applied to the lower end face of the punched hole to flatten the lower end face.

[0045] During this process, the pressing of the first straight chamfer 3, the first rounded chamfer 4, the transition rounded surface 5, the step 6, and the pre-turned rounded chamfer 7 will all make the structure of the metal plate 1 relative to the punching hole 2 more compact. In addition, by reducing the height of the punching surface, the possibility of cracks appearing in this part during the turning process is reduced.

[0046] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fine blanking process for reducing cracking on the end face of a borehole, characterized in that: The process includes the following steps: S1, a vertical punch hole (2) is pre-punched on a horizontally placed metal plate (1), a first pressing straight chamfer (3) is simultaneously pressed on the metal plate (1) relative to the top of the punch hole (2), a first pressing rounded chamfer (4) is simultaneously pressed on the metal plate (1) relative to the bottom of the punch hole (2), the chamfer depth of the first pressing straight chamfer (3) is greater than the chamfer depth of the first pressing rounded chamfer (4), a transition rounded surface (5) is simultaneously pressed on the metal plate (1) relative to the first pressing straight chamfer (3) and the punching surface, and a step (6) is simultaneously pressed on the metal plate (1) relative to the first pressing rounded chamfer (4) and the punching surface in step S1; S2. The top of the metal plate (1) is deformed downward relative to the punch hole (2) under pressure, causing a depression to form at the edge of the punch hole (2); S3. The edge of the punch hole (2) continues to deform downward under force, causing the edge of the punch hole (2) to fold downward to vertical, and the punching surface of the punch hole (2) folds to form the lower end face; S4. Apply an upward pressing force to the lower end face of the hole to flatten it.

2. The fine blanking process for reducing cracking at the end face of the borehole according to claim 1, characterized in that: After step S1 is completed, the height of the punched (2) cutting surface is 0.3-0.35 times the thickness of the metal plate (1).

3. The fine blanking process for reducing cracking at the end face of the borehole according to claim 1, characterized in that: After step S2 is completed, the height of the punched (2) cutting surface is 0.15-0.2 times the thickness of the metal plate (1).

4. The fine blanking process for reducing cracking at the end face of the borehole according to claim 1, characterized in that: In step S2, the position of the metal plate (1) relative to the first pressing straight chamfer (3) and the transition arc surface (5), the first pressing arc chamfer (4) and the step (6) are all pressed into a pre-flipped arc chamfer (7).

5. The fine blanking process for reducing cracking at the end face of the borehole according to claim 4, characterized in that: In step S2, the pre-turned rounded chamfer (7) at the top of the metal plate (1) relative to the punched hole (2) is S-shaped.

Images