DEVICE FOR STAMPING AND PUNCHING THROUGH A SHEET-LIKE WORKPIECE

Abstract

A device for stamping a depression in a sheet-like workpiece and for piercing the workpiece in the region of the stamped depression, including a punch unit and a die unit between which the workpiece can be positioned. The punch unit has a punch with a forming punch and with a piercing punch. The forming punch bears against a side of the workpiece in the region of the depression during the stamping of the depression. The piercing punch pierces the workpiece in the region of the depression. The forming punch and the piercing punch are moved along a joining axis of the device. The forming punch and the piercing punch are accommodated in a punch housing, and the forming punch and the piercing punch are driven via a common hydraulic supply system relative to the punch housing along the joining axis of the device.

Claims

1. A device for stamping a depression in a sheet-like workpiece and for piercing the workpiece in the region of the stamped depression, comprising a punch unit and a die unit opposite the punch unit, wherein the workpiece which can be processed by the device can be positioned between the punch unit and the die unit, wherein the punch unit has a punch with a forming punch and with a piercing punch, wherein the forming punch is designed to come to bear against a side of the workpiece in the region of the depression during the stamping of the depression, and wherein the piercing punch is configured to pierce the workpiece in the region of the depression, wherein the forming punch and the piercing punch can be moved by being driven along a joining axis of the device, wherein the forming punch and the piercing punch are accommodated in a punch housing, wherein the forming punch and the piercing punch can be driven via a common hydraulic supply system relative to the punch housing along the joining axis of the device.

2. The device as claimed in claim 1, wherein the punch unit has a first hydraulic space and a second hydraulic space which are hydraulically separated from each other inside the punch housing.

3. The device as claimed in claim 2, wherein the first hydraulic space is connected to the hydraulic supply system via a first hydraulic connection.

4. The device as claimed in claim 2, wherein the second hydraulic space of the punch unit is connected to the hydraulic supply system via a second hydraulic connection.

5. The device as claimed in claim 2, wherein the first hydraulic space and the second hydraulic space are connected to a high-pressure space of the hydraulic supply system.

6. The device as claimed in claim 2, wherein the first hydraulic space of the punch unit only acts on a forward stroke side of the piercing punch.

7. The device as claimed in claim 2, wherein the second hydraulic space of the punch unit acts on a return stroke side of the piercing punch and on a forward stroke side of the forming punch.

8. The device as claimed in claim 3, wherein the first hydraulic connection comprises a valve arrangement for opening and/or closing the first hydraulic connection.

9. The device as claimed in claim 4, wherein the second hydraulic connection cannot be shut off.

10. The device as claimed in claim 2, wherein the first hydraulic space is connected to a low-pressure space of the hydraulic supply system.

11. The device as claimed in claim 3, wherein the first hydraulic connection is connected to a low-pressure space of the hydraulic supply system via an interconnection.

12. The device as claimed in claim 8, wherein the valve arrangement for opening and/or closing a connecting section is formed between the high-pressure space and the interconnection.

13. The device as claimed in claim 1, wherein the hydraulic supply system comprises a hydropneumatic pressure intensifier device.

14. The device as claimed in claim 1, further comprising a drive designed to drive the punch unit in such a way that the forming punch and the piercing punch can be driven jointly relative to the die unit along the joining axis of the device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Further features and advantages of the present invention are described in detail with the aid of an exemplary embodiment shown in the drawings of a device according to the present invention.

[0045] FIG. 1 shows a highly schematized schematic diagram of a device according to the present invention with the aid of a view in section of the device; and

[0046] FIGS. 2 to 5 show part of a schematized device according to the present invention in each case in a longitudinal section in different operating states, wherein the plane of section according to FIG. 5 is perpendicular to the plane of section according to FIGS. 2 to 4.

DETAILED DESCRIPTION OF THE INVENTION

[0047] In FIGS. 1-5, in each case part of a device 1 according to the present invention for stamping a depression 2 (see FIGS. 4 and 5) into a sheet-like workpiece 3 and for piercing the workpiece 3 in the region of the stamped depression 2 is shown. The device 1 is designed as stamping/piercing tongs 4, referred to below as tongs 4.

[0048] The tongs 4 are shown in FIG. 2 in a purely schematic fashion, with a punch unit 5 and with a die unit 6 situated opposite the punch unit 6 along a joining axis F, wherein the workpiece 3 which can be processed with the tongs 4 is held between the punch unit 5 and the die unit 6 in its flat, plane starting form, i.e. before a stamping and piercing processing step. The workpiece 3 is, for example, a sheet-metal workpiece and consists of, for example, a metal material which is just a few millimeters thick.

[0049] The punch unit 5 comprises a punch 7 with a forming punch 8 and a piercing punch 9. When it stamps the depression 2, the forming punch 8 comes to bear against a workpiece side 3a in the region of the depression 2. After the stamping procedure, the piercing punch 9 pierces the workpiece 3 in the region of the depression 2 with an elongated piercing section 11, protruding from a base body 10 of the piercing punch 9 and comprising two piercing pins 12, 13.

[0050] The forming punch 8 and the piercing punch 9 are accommodated in a punch housing 14 which can be moved by being driven linearly in a direction R1 and in a direction R2, relative to the die unit 6, by means of a drive unit such as an electric drive 15 (see FIG. 2). The punch unit 5 is driven by means of the electric drive 15 in such a way that the forming punch 8 and the piercing punch 9 can be driven jointly with the punch housing 14 relative to the die unit 6 along the joining axis F.

[0051] Accordingly, the punch 7, or the forming punch 8 and the piercing punch 9, can be moved by being driven jointly linearly along the joining axis F in the direction R1 toward the die unit 6 and back in the direction R2 which is opposed to the direction R1.

[0052] To manage the operation of the tongs 4, a higher-order programmable control unit (not shown), for example, with a computer unit, is present.

[0053] According to the present invention, the forming punch 8 and the piercing punch 9 can be driven via a common hydraulic supply system 16 relative to the punch housing 14 along the joining axis F or the tongs 4.

[0054] The punch unit 5 preferably has a first hydraulic space 17 and a second hydraulic space 18 inside the punch housing 14. The hydraulic spaces 17 and 18 filled with a hydraulic fluid such as, for example, a hydraulic oil are hydraulically separated from each other inside the punch housing 14 by the punch housing 14 and, for example, by closed annular seals 19 circumferentially with respect to the joining axis F, on the outside of the base body 10. The annular seals 19 provide a seal against an inner side 14a of the punch housing 14.

[0055] The first hydraulic space 17 is connected to the hydraulic supply system 16 via a first hydraulic connection 20.

[0056] The second hydraulic space 18 is connected to the hydraulic supply system 16 via a second hydraulic connection 21.

[0057] The first hydraulic space 17 and the second hydraulic space 18 are connected to a high-pressure space 22 of the hydraulic supply system 16. The high-pressure space 22 is likewise filled with the hydraulic fluid.

[0058] The first hydraulic space 17 acts on the punch 7 with respect to only a forward stroke side 9a of the piercing punch 9 or the base body 10.

[0059] The second hydraulic space 18 acts on a return stroke side 9b of the piercing punch 9 and on a forward stroke side 8a of the forming punch 8.

[0060] The first hydraulic connection 20, for example, a hydraulic line such as a hydraulic hose line, has a valve arrangement 23, preferably with a valve 24 and a valve 25, for opening and/or closing the first hydraulic connection 20.

[0061] The second hydraulic line 21, for example, a hydraulic hose line, can here by way of example not be shut off or does not have a valve arrangement. The second hydraulic space 19 is always hydraulically connected to the high-pressure space 22 of the hydraulic supply system 16.

[0062] The hydraulic supply system 16 comprises a hydropneumatic pressure intensifier device 26 with a housing 27 to which indicated pneumatic lines 28, 29 are attached.

[0063] The high-pressure space 22 and a low-pressure space 31 are present inside the housing 27 of the pressure intensifier device 26. The operating principle of the pressure intensifier device 26 is explained further below.

[0064] The first hydraulic space 17 can be connected hydraulically conductively in a selective fashion to the high-pressure space 22 and/or to the low-pressure space 31 of the hydraulic supply system 16.

[0065] For this purpose, branching off from the first hydraulic connection 20, an interconnection 32 is attached to the latter for connection to the low-pressure space 31. The interconnection 32 is attached at one end to the low-pressure space 31 and at the other end to the hydraulic supply system 20. The interconnection 32 has a valve 33 for opening and/or shutting off the interconnection 32.

[0066] The valve arrangement 23 comprises the valve 25 for opening and/or closing a connecting section 20a between the high-pressure space 22 and the interconnection 32 or a junction of the interconnection 32 with the hydraulic connection 20. The connecting section 20a is part of the hydraulic connection 20 between the junction of the interconnection 32 and an opening, hydraulically connected to the high-pressure space 22, in the housing 27.

[0067] A pressure intensifier piston 34 and a storage piston 35 can be moved linearly in the direction R3 and back in the direction R4 inside the housing 27 of the hydropneumatic pressure intensifier device 26. The pressure intensifier piston 34 has a piston section 34a with a larger diameter and a piston rod 36 which is connected thereto, extends centrally and has a smaller diameter than the piston section 34a.

[0068] Compressed air is applied via the pneumatic line 28 to a pneumatic space 37, on the forward stroke side and enclosed by the housing 27, of the pressure intensifier device 26 in order to move the pressure intensifier piston 34 in displacement in the direction R3.

[0069] Compressed air is applied via the pneumatic line 29 to a pneumatic space 38, on the return stroke side and enclosed by the housing 27, of the pressure intensifier device 26 in order to move the pressure intensifier piston 34 in displacement in the direction R4.

[0070] Compressed air is applied via the pneumatic line 30 to a pneumatic space 39, on the forward stroke side and enclosed by the housing 27, of the pressure intensifier device 26 in order to move the storage piston 35 in displacement in the direction R3. The return stroke of the storage piston 35 in the direction R4 is effected by hydraulic fluid flowing into the low-pressure space 31 filled with hydraulic fluid.

[0071] A relatively high hydraulic pressure in the high-pressure space 22 is established when the pressure intensifier piston 34 is displaced in the direction R3 and is plunged into a narrowed portion 40 which has a circumferential seal 41. When the piston rod 36 is plunged into the narrowed portion 40, the wall of the narrowed portion 40 and an outer side of the piston rod 36 are hydraulically sealed with respect to each other by virtue of the seal 41 such that the high-pressure space 22 and the low-pressure space 31 are hydraulically separated at the narrowed portion 40.

[0072] The die unit 6 has a punch-side end side 6a for the workpiece 3 to bear on one side. A die retaining means or die ring 43 which can move linearly along the joining axis F via a spring is accommodated around a central die body 42 which is fixed in position. In a basic position of the device 1 according to FIG. 2, a plane flat bearing surface is provided by the die body 42 and die ring 43 being effectively flush with the punch unit 5.

[0073] The mode of operation of the tongs 4 according to the present invention is explained below with the aid of FIGS. 2 to 5 in which the tongs 4 according to FIG. 1 are illustrated in greater detail, wherein only part of the tongs 4 is shown comprising parts of the punch unit 5 and the die unit 6.

[0074] The basic position of the device 1 is shown in FIG. 2 in which the tongs 4 are open and the punch unit 5 has been retracted in the direction R2, this being effected by the electric drive 15. Relative to an end side 5a of the punch unit 5, the forming punch 8 is situated in a position extended in the direction R1, wherein the piercing punch 9 is lowered or withdrawn in the forming punch or is retracted in the direction R2. There is no workpiece present between the punch unit 5 and the die unit 6.

[0075] According to FIG. 3, which corresponds to the state according to FIG. 1, the tongs 4 is closed by the drive 15, wherein the workpiece 3 is fixed between the punch unit 5 and the die unit 6 or bears against the end side 6a of the die unit 6 with one surface side and is in contact at the end with the end side 5a on the forming punch 8 with the other surface side. The forming punch 8 is extended in the direction R1 by hydraulic pressure which is provided by the pressure intensifier device 26 via the second hydraulic connection 21. The hydraulic pressure in the second hydraulic space 18 accordingly acts on the forward stroke side on the forming punch 8 and on the return stroke side on the piercing punch 9. The piercing punch 9 is therefore retracted in the direction R2 and does not project with its piercing section 11 or with the two withdrawn piercing pins 12, 13 beyond an end side of the forming punch 8 which is opposite the end side 6a of the die unit 6.

[0076] The intensifier piston 34 of the pressure intensifier device 26 is activated pneumatically on the forward stroke side and is extended in the direction R3 in a so-called power stroke. The piston rod 36 is thus plunged into the narrowed portion 40. Hydraulic high pressure is generated in the high-pressure space 22, wherein compressed hydraulic fluid is pumped from the high-pressure space 22 into the low-pressure space 31, which additionally functions as a storage space, via the valves 25 and 33 which are open or have been switched to be open and via the connecting section 20a and the interconnection 32. The valve 24 is closed and shuts off the first hydraulic connection 20 to the hydraulic space 17.

[0077] In the next step, the stamping is effected (see FIG. 4) and the depression 2 is formed by means of the drive 15. All three valves 24, 25 and 33 are closed. Depending on the movement path covered by the punch unit 5 in the direction R1, a predeterminable forming depth t of the depression 2 is formed in the workpiece 3, relative to the undeformed regions of the workpiece 3. The forming depth t is, for example, up to 8 millimeters. The movement of the punch unit 5 causes the punch housing 14 to travel in the direction R1, wherein the forming punch 8 moves backward in the direction R2 relative to the punch housing 14, wherein at the same time the die retaining means or the die ring 43 moves backward in the direction R1. The end side of the forming punch 8 which faces the die unit 6 is applied to the base of the depression 2. The forming punch 8 is pushed backward in the direction R2 counter to the hydraulic pressure existing in the high-pressure space 18. As a result, by virtue of the closed valves 24, 25 and 33, when the forming punch 8 is forced backward, hydraulic fluid is forced out of the hydraulic space 18 which is becoming smaller and into the high-pressure space 22 via the hydraulic connection 21. The intensifier piston 34 and the piston rod 36 are displaced backward, counter to the power stroke pressure in the high-pressure space 22, by an amount corresponding to the amount of hydraulic fluid forced out. The hydraulic forming force prevailing in the high-pressure space 22 remains constant.

[0078] According to FIG. 5, when the electric drive 15 is not running, the piercing procedure takes place hydraulically or is determined by the hydraulic supply system 16. The forming punch 8 furthermore bears against the workpiece 3 or the depression 2 under high pressure. The piercing punch 9 with its two piercing pins 12, 13 is extended hydraulically until it abuts an abutment 45 on the forming punch 8. The pressure intensifier piston 34 is retracted by a certain amount for a short period in the direction R4 so that a sufficient volume of hydraulic fluid is present in the high-pressure space 22 in front of the piston rod 36. The repeated extension of the pressure intensifier piston 34 then takes place in the direction R3, as a result of which a power stroke occurs with a high-pressure state in the high-pressure space 22. The valves 24 and 25 are open and the valve 33 is closed. This causes hydraulic fluid to be forced at high pressure from the high-pressure space 22 and into the hydraulic space 17 via the hydraulic connection 20 and the piercing punch is extended in the direction R1. After the workpiece 3 is pierced in the region of the depression 2 by the piercing pins 12 and 13, as a result of which two holes are created in the workpiece according to the size and shape of the end side of the respective piercing pins 12, 13, the processing of the workpiece 3 is completed. The tongs 4 are then restored to the basic position according to FIG. 2.

[0079] The tongs 4 are opened by means of the drive 15, wherein the punch unit 5 travels in the direction R2. The forming punch 8 moreover is extended in the direction R1 hydraulically as far as an abutment 46 on the punch housing (see FIG. 2). The piercing piston 9 is then retracted hydraulically in the direction R2 into the basic position. For this purpose, hydraulic high pressure is established in the hydraulic space 18 which acts on the forward stroke side on the forming punch 8 and on the return stroke side on the piercing piston 9. The valves 24 and 33 are open for this purpose. The valve 25 is closed and shuts off the throughflow to the high-pressure space 22 and allows the hydraulic fluid to flow back into the low-pressure space 31.

LIST OF REFERENCE NUMERALS

[0080] 1 device [0081] 2 depression [0082] 3 workpiece [0083] 3a workpiece side [0084] 4 stamping/piercing tongs [0085] 5 punch unit [0086] 5a end side [0087] 6 die unit [0088] 6a end side [0089] 7 punch [0090] 8 forming punch [0091] 8a forward stroke side [0092] 9 piercing punch [0093] 9a forward stroke side [0094] 9b return stroke side [0095] 10 base body [0096] 11 piercing section [0097] 12 piercing pin [0098] 13 piercing pin [0099] 14 punch housing [0100] 14a inner side [0101] 15 drive [0102] 16 hydraulic supply system [0103] 17 hydraulic space [0104] 18 hydraulic space [0105] 19 annular seal [0106] 20 hydraulic connection [0107] 20a connecting section [0108] 21 hydraulic connection [0109] 22 high-pressure space [0110] 23 valve arrangement [0111] 24 valve [0112] 25 valve [0113] 26 pressure intensifier device [0114] 27 housing [0115] 28 line [0116] 29 line [0117] 30 line [0118] 31 low-pressure space [0119] 32 interconnection [0120] 33 valve [0121] 34 pressure intensifier piston [0122] 34a piston section [0123] 35 storage piston [0124] 36 piston rod [0125] 37 pneumatic space [0126] 38 pneumatic space [0127] 39 pneumatic space [0128] 40 narrowed portion [0129] 41 seal [0130] 42 die body [0131] 43 die ring [0132] 44 spring [0133] 45 abutment [0134] 46 abutment