Punching die

Abstract

The disclosure relates to a die-cutting die comprising a carrier (10). An insert (20) is inserted into the end face of the carrier (10), which encompasses the through-hole (22) of the die-cutting die.

Description

Field of the invention

[0001] The invention relates to a punching die and a method for punching holes. Furthermore, the invention relates to a punching tool, which is used in particular for punching holes in the bodywork area. Background of the invention

[0002] Punching holes in body panels is common practice. Especially when the panel is accessible from both sides, using a hydraulic punching tool to create holes, which are used for riveting during repairs, for example, is less time-consuming and costly than drilling.

[0003] Drilling a hole is particularly complex when working with high-strength sheet metal, especially composite structures. High-strength special drill bits are required, which wear out relatively quickly.

[0004] But punching holes in high-strength sheet metal is also problematic.

[0005] In punching, a punch cuts into the sheet metal, and a die acts as a counter-holder. With high-strength sheets, the material hardly flows during the punching process when the punch cuts into it. Instead, the slugs are essentially broken out.

[0006] The stress on the cutting edge of the punch is enormous. German patent application DE 10 2013 114 806 A1 (inventor Klaus Reitzig) discloses a punch onto which an annular die crown can be fitted. The die crown can be removed after each punching operation and replaced with a new one. This ensures that a punch with a sufficiently sharp cutting edge is used for every punching operation. The dimensional accuracy of the punched holes is therefore not affected by wear on the punch itself. At the same time, punching holes, especially in high-strength body structure components, becomes more cost-effective, as only the die crown needs to be replaced. Object of the invention

[0007] In contrast, the invention is based on the objective of further improving the precision of punching holes, especially in high-strength body panels. Summary of the invention

[0008] The object of the invention is already achieved by a die according to claim 1. Preferred embodiments and further developments of the invention can be found in the subject matter of the dependent claims, the description, and the drawings.

[0009] The invention relates to a punch die, which is used in particular for a hydraulic tool for punching holes in body panels, especially high-strength body panels.

[0010] The die-cutting die includes a carrier.

[0011] The carrier is designed to be connected to a punching tool. In particular, the carrier can comprise a receptacle that serves to connect it to the punching tool.

[0012] According to the invention, an insert is inserted into the front side of the carrier, which insert encompasses the through hole of the punching die.

[0013] The die according to the invention, hereinafter also referred to simply as "die", is therefore designed in at least two parts and comprises the carrier and the insert, which includes the through hole and the contact surface for the workpiece.

[0014] Preferably, the insert protrudes from the carrier. Therefore, only the insert comes into contact with the tool during a punching operation.

[0015] It has turned out that the edge of the through-hole, against which the workpiece rests during punching, plays a surprisingly significant role in the dimensional accuracy of the punched hole.

[0016] In particular, the edge of the through-hole, against which the workpiece rests, also appears to play an important role in the quality of the punching process on the die side.

[0017] The insert is preferably designed as a ring, in particular as a ring with a circular cylindrical outer diameter.

[0018] According to one embodiment, the through-hole of the insert has a diameter of 3 to 15 mm.

[0019] According to a preferred embodiment of the invention, the insert is clamped into a recess of the carrier.

[0020] In particular, the insert is designed as an oversize fit relative to the recess.

[0021] The insert is clamped into the recess. To replace the insert, it can be punched out of the recess. For this purpose, the carrier preferably includes a through hole below the insert.

[0022] In a further development of the invention, a circumferential groove is arranged in the recess, into which an elastic ring, in particular an O-ring, is inserted.

[0023] The elastic ring also serves to clamp the insert in place. In a preferred embodiment, both the elastic ring and an interference fit are provided for the clamping connection.

[0024] Preferably, the insert is made of a harder material than the carrier.

[0025] In particular, the insert can be made of a hardened alloy with a hardness HRC greater than 60, preferably from 60 to 65 (according to DIN EN ISO 6508-1 -2016-12).

[0026] The hardness of the carrier material preferably differs by at least 5 degrees of hardness according to HRC.

[0027] In particular, the carrier can have a hardness of 50 to 58 HRC.

[0028] The insert is preferably through-hardened. The carrier may be unhardened or only surface-hardened.

[0029] For example, a harder, yet more brittle material is used for the insert. The carrier material is softer but has a higher elongation at break, thus avoiding the risk of sudden component failure due to fracture.

[0030] According to one embodiment of the invention, the recess is designed as a blind hole with a collar that engages under the insert.

[0031] The collar surrounds the insert from below. Preferably, however, the collar ends radially in front of the inner edge of the insert's through-hole.

[0032] This allows access to a portion of the underside of the insert in order to knock it out.

[0033] In a preferred embodiment of the invention, the through-hole has an undercut.

[0034] The undercut can be designed in particular as a cone, which is adjacent to a circular cylindrical section of the through hole.

[0035] The side wall of the undercut can be positioned at an angle of 10 to 20° to the central axis of the insert.

[0036] In one embodiment of the invention, the insert has a ratio of wall thickness to outer diameter (largest outer diameter) of 0.1 to 0.5, preferably of 0.2 to 0.3.

[0037] The wall of the insert is therefore preferably comparatively thick.

[0038] The ratio of height to outer diameter of the insert is preferably 0.2 to 2, particularly preferably 0.4 to 0.8.

[0039] The insert is therefore preferably designed not as a flat disc, but as a component with a relatively large height, which largely prevents warping of the insert during stamping.

[0040] The invention further relates to a stamping tool comprising the die described above.

[0041] The punching tool is designed in particular as a hydraulic tool with an exchangeable punching die and an exchangeable punching punch.

[0042] The invention further relates to a method for punching holes, in particular in high-strength body panels.

[0043] According to the method, the punching die described above is used.

[0044] After punching the first hole, the insert is replaced and then a second hole is punched.

[0045] Regularly replacing the insert ensures consistent dimensional accuracy of the punched holes. Brief description of the drawings

[0046] The subject matter of the invention will be explained below with reference to an example shown in the drawings Fig. 1 to Fig. 3 illustrated embodiment will be explained in more detail. Fig. 1 is a side view of a punching die according to the invention. Fig. 2is a central longitudinal section of the punching die. Fig. 3 shows the punching die and the punch used in conjunction with the die. Detailed description of the drawings

[0047] Fig. 1 shows a side view of an embodiment of a punching die 1 according to the invention.

[0048] The die 1 comprises a carrier 10, which comprises a rear receptacle 11 with which the carrier 10 can be attached to a hydraulic pressing tool.

[0049] The carrier 10 is preferably circular-cylindrical.

[0050] The carrier 10 is hollow inside and in this embodiment comprises a lateral opening 12 and a through hole 13.

[0051] The punched slug can be removed through the side opening 12. If a part becomes jammed, it can be pushed out from the opposite side using a tool.

[0052] An insert 20 is inserted into the end face of the carrier 10, which forms the contact surface for the workpiece.

[0053] Fig. 2 is a central longitudinal section along line BB from Fig. 1 .

[0054] The insert 20 is inserted into a recess 17 of the carrier 10.

[0055] The insert 20 is clamped in the recess 17 via an interference fit.

[0056] Additionally, the recess 10 includes an internal groove 15 into which an O-ring 2 is inserted.

[0057] The recess 17 forms a blind hole with a collar 16 that engages under the insert 20 and thus supports the insert 20.

[0058] The collar 16 ends before the inner edge 26 of the insert 20. This allows a suitable tool to grip the underside of the insert 20 in order to knock it out.

[0059] For example, a tool with an expandable head and a movable weight, which serves as a pulling hammer, can be used to knock out the insert 20 (not shown).

[0060] The recess 17 includes a conical insertion section 14 on its end face. This facilitates the insertion of the insert 20.

[0061] Insert 20 has a circular cylindrical outer contour.

[0062] The front edge 24 is rounded.

[0063] Insert 20 protrudes from recess 17.

[0064] The inner lower edge 25 is chamfered, in particular conically shaped, which also facilitates the insertion of the insert 20.

[0065] When punching, it is important that the edge 21 of the through hole 22 which rests against the workpiece is sufficiently sharp.

[0066] The through-hole 22 comprises a circular-cylindrical section followed by an undercut 23. In the area of ​​the rear section, the diameter of the through-hole 22 widens. This facilitates the removal of the punched-out sheet metal piece.

[0067] The insert 20 is made of a harder, but at the same time more brittle material with lower elongation at break compared to the carrier 10.

[0068] Fig. 3 shows how the die 1 according to the invention is used in a corresponding tool.

[0069] In addition to the die 1, a punch 30 is attached to the hydraulic tool (not shown).

[0070] In this embodiment, the punch comprises a mandrel 31 onto which a punch crown 32 is placed.

[0071] The die crown 32 forms the counterpart to the die 1, especially to the insert 20.

[0072] The punching punch 30 cuts into the sheet metal with the punching crown 32 in front and moves into the through hole of the insert 20.

[0073] As already described at the beginning, with high-strength sheets and sheet pairings, there is less cutting by the punch die 30. The punched-out piece of sheet metal, the so-called punch slug, is essentially broken out.

[0074] The invention further improved the dimensional accuracy of holes punched into body panels. Furthermore, if the edge of the die's through-hole becomes worn, only the insert needs to be replaced. List of reference symbols

[0075] 1 Die / Matrices 2 O-ring 10 Carrier 11 Receptacle 12 Side opening 13 Through hole 14 Insertion section 15 Groove 16 Collar 17 Recess 20 Insert 21 Inner edge 22 Through hole 23 Undercut 24 Edge 25 Edge 26 Edge 30 Punch 31 Mandrel 32 Punch crown

Claims

1. Punching die comprising a carrier, wherein an insert is inserted into the carrier at the end face, which insert encompasses the through hole of the punching die.

2. Punching die according to the preceding claim, characterized in that the insert is designed as a ring.

3. Punching die according to one of the preceding claims, characterized in that the insert is clamped into a recess of the carrier, wherein in particular the insert is designed as an interference fit with respect to the recess.

4. Punching die according to one of the preceding claims, characterized in that a circumferential groove is arranged in the recess into which an elastic ring is inserted.

5. Punching die according to one of the preceding claims, characterized in that the insert is made of a harder material than the carrier, in particular of a material with a hardness HRC greater than 60, preferably 60-65 (according to DIN EN ISO 6508-1 - 2016-12).

6. Punching die according to one of the preceding claims, characterized in that the insert is designed to be removable from the carrier.

7. Punching die according to one of the preceding claims, characterized in that the recess is designed as a blind hole with a collar that engages under the insert.

8. Punching die according to one of the preceding claims, characterized in that the through hole has an undercut.

9. Punching die according to one of the preceding claims, characterized in that the insert has a wall thickness to outer diameter ratio of 0.1 to 0.5, preferably 0.2-0.

3.

10. Punching die according to one of the preceding claims, characterized in that the insert has a height to outer diameter ratio of 0.2 to 2, preferably 0.4 to 0.

8.

11. A punching tool comprising a punching die according to any one of the preceding claims.

12. A method for punching holes, particularly in high-strength body panels, wherein a punching die according to one of the preceding claims is used and wherein after punching a first hole, the insert is exchanged and then a second hole is punched.

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