Die, die and die-cutting process

Abstract

The disclosure relates to a die-cutting die comprising a carrier. An insert is fitted into the end face of the carrier, which encompasses the through-hole of the die-cutting die.

Description

Field of invention

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

[0002] It is known to punch holes in body panels. Especially when the panel is accessible from both sides, creating holes, for example for setting rivets during repairs, using a hydraulic punching tool is less time-consuming and expensive than drilling.

[0003] Drilling a hole is particularly difficult with high-strength sheet metal, especially in composite structures. It requires the use of special high-strength drill bits, 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.

[0007] Document DD 288 329 A5 shows a locking tool with a cutting die. Object of the invention

[0008] 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

[0009] The object of the invention is already achieved by a die according to claim 1. The object is also achieved by a die according to claim 8 or a die-cutting method according to claim 9. Preferred embodiments and further developments of the invention can be found in the subject matter of the dependent claims, the description, and the drawings.

[0010] 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.

[0011] The die-cutting die includes a carrier.

[0012] The carrier is designed to be connected to a punching tool. In particular, the carrier may include a receptacle that serves for connection to the punching tool.

[0013] According to the invention, an insert is placed in the front face of the carrier, which encompasses the through-hole of the die.

[0014] 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.

[0015] Preferably, the insert protrudes from the carrier. Therefore, only the insert comes into contact with the tool during a punching operation.

[0016] It has been found 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.

[0017] 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.

[0018] The insert is preferably designed as a ring, in particular as a ring with a circular cylindrical outer diameter.

[0019] According to one embodiment, the through-hole of the insert has a diameter of 3 to 15 mm.

[0020] According to a preferred embodiment of the invention, the insert is clamped into a recess of the carrier.

[0021] In particular, the insert is designed as an oversize fit relative to the recess.

[0022] The insert is thus 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.

[0023] 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.

[0024] 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.

[0025] Preferably, the insert is made of a harder material than the carrier.

[0026] 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).

[0027] The hardness of the carrier material preferably differs by at least 5 degrees of hardness according to HRC.

[0028] In particular, the carrier can have a hardness of 50 to 58 HRC.

[0029] The insert is preferably through-hardened. The carrier may be unhardened or only surface-hardened.

[0030] For this purpose, a harder but more brittle material is used. The carrier material is softer but has a higher elongation at break, thus avoiding the risk of sudden component failure due to fracture.

[0031] According to one embodiment of the invention, the recess is designed as a blind hole with a collar that engages under the insert.

[0032] 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.

[0033] This allows access to a portion of the underside of the insert in order to knock it out.

[0034] In a preferred embodiment of the invention, the through-hole has an undercut.

[0035] The undercut can be designed in particular as a cone, which is adjacent to a circular cylindrical section of the through hole.

[0036] The side wall of the undercut can be positioned at an angle of 10 to 20° to the central axis of the insert.

[0037] 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.

[0038] The wall of the insert is therefore preferably comparatively thick.

[0039] The ratio of height to outer diameter of the insert is preferably 0.2 to 2, particularly preferably 0.4 to 0.8.

[0040] 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.

[0041] The invention further relates to a stamping tool comprising the die described above.

[0042] The stamping tool is designed in particular as a hydraulic tool with an interchangeable stamping die and an interchangeable stamping punch.

[0043] The invention further relates to a method for punching holes, in particular in high-strength body panels.

[0044] The die described above is used in accordance with the procedure.

[0045] After punching a first hole, the insert is replaced and then a second hole is punched.

[0046] Regular replacement of the insert ensures consistent dimensional accuracy of the punched holes. Brief description of the drawings

[0047] The subject matter of the invention will be described below with reference to the drawings. Fig. 1 to Fig. 3. This will be explained in more detail in the illustrated embodiment. Fig. Figure 1 is a side view of a die according to the invention. Fig. 2 is a central longitudinal section of the die. Fig. Figure 3 shows the die and the die-cutting punch used in conjunction with the die. Detailed description of the drawings

[0048] Fig. Figure 1 shows a side view of an embodiment of a die according to the invention.

[0049] The die 1 comprises a carrier 10, which includes a rear receptacle 11 with which the carrier 10 can be attached to a hydraulic pressing tool.

[0050] The support 10 is preferably designed in a circular cylindrical shape.

[0051] The support 10 is hollow inside and in this embodiment includes a lateral opening 12 and a through hole 13.

[0052] The die 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.

[0053] An insert 20 is inserted into the end face of the carrier 10, which forms the contact surface for the workpiece.

[0054] Fig. 2 is a central longitudinal section along line BB from Fig. 1.

[0055] The insert 20 is inserted into a recess 17 of the carrier 10.

[0056] The insert 20 is clamped in the recess 17 via an interference fit.

[0057] Additionally, the recess 10 includes an internal groove 15 into which an O-ring 2 is inserted.

[0058] The recess 17 forms a blind hole with a collar 16 that engages under the insert 20 and thus supports the insert 20.

[0059] 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.

[0060] For example, a tool with an expanding head and a sliding weight, which serves as a slide hammer, can be used to knock out the insert 20 (not shown).

[0061] The recess 17 includes a conical insertion section 14 on its end face. This facilitates the insertion of the insert 20.

[0062] Insert 20 has a circular cylindrical outer contour.

[0063] The front edge 24 is rounded.

[0064] Insert 20 protrudes from recess 17.

[0065] The inner lower edge 25 is chamfered, in particular conically shaped, which also facilitates the insertion of the insert 20.

[0066] When punching, it is important that the edge 21 of the through hole 22 which rests against the workpiece is sufficiently sharp.

[0067] The through-hole 22 comprises a circular cylindrical section followed by an undercut 23. In the area of ​​the undercut, the diameter of the through-hole 22 widens. This facilitates the removal of the punched-out sheet metal piece.

[0068] 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.

[0069] Fig. Figure 3 shows how the die 1 according to the invention is used in a corresponding tool.

[0070] In addition to the die 1, a punch 30 is attached to the hydraulic tool (not shown).

[0071] In this embodiment, the punch comprises a mandrel 31 onto which a punch crown 32 is placed.

[0072] The die crown 32 forms the counterpart to the die 1, especially to the insert 20.

[0073] The punch 30 cuts into the sheet metal with the punch crown 32 leading and travels into the through hole of the insert 20.

[0074] 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.

[0075] 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. Reference symbol list 1 die / die 2 O-rings 10 carriers 11th entry 12 side openings 13 Through hole 14 Introductory section 15 Nut 16 collars 17 Exclusion 20 deployment 21 Inner edge 22 Through hole 23 Undercut 24 edge 25 edge 26 edge 30 die-cutting stamps 31 Dorn 32 stamped crowns

Claims

[1] Punching die (1), comprising a carrier (10) which has a rear receptacle (11) with which the carrier (10) can be fastened to a hydraulic pressing tool, wherein an insert (20) is inserted into the front side of the carrier (10), which insert comprises the through hole (13) of the punching die (1), wherein the insert (20) is designed to be removable from the carrier (10). [2] Punching die (1) according to the preceding claim, characterized by that the insert (20) is designed as a ring. [3] Punching die (1) according to one of the preceding claims, characterized by that the insert (20) is clamped into a recess (17) of the carrier (10). [4] Punching die (1) according to one of the preceding claims, characterized by that a circumferential groove (15) is arranged in the recess (17) into which an elastic ring is inserted. [5] Punching die (1) according to one of the preceding claims, characterized bythat the insert (20) is made of a harder material than the carrier (10) [6] Punching die (1) according to one of the preceding claims, characterized by that the recess (17) is designed as a blind hole with a collar (16) engaging under the insert (20). [7] Punching die (1) according to one of the preceding claims, characterized by that the through hole (13) has an undercut (23), and / or that the insert has a wall thickness to outer diameter ratio of 0.1 to 0.5, preferably 0.2-0.3, and / or a height to outer diameter ratio of 0.2 to 2, preferably 0.4 to 0.

8. [8] Punching tool (1) comprising a punching die (1) according to one of the preceding claims. [9] Method for punching holes, wherein a punching die (1) according to one of the preceding claims is used and wherein after punching a first hole, the insert (20) is exchanged and then a second hole is punched.

Images