EP0893178B1 - Punching and stamping tool - Google Patents

Description

The invention relates to a stamping and embossing tool according to the preamble of claim 1. Such a tool is known from DE-A 23 45 017.

Such stamping and embossing tools are used to connect two joining parts, preferably Sheet metal, using a rivet. Such rivets have a rivet head and a groove on the shaft In the known tools, the two are placed on an anvil Joined parts are pressed together by a spring-loaded hold-down device, whereupon the rivet needle presses the rivet into the parts to be joined, and in this way punching slugs from the Parts to be punched out. With the further downward movement of the rivet needle the rivet head is pressed into the punched-out part of the upper part. After that, through a stamp of the edge of the anvil's bore is pressed into the lower joining part, the displaced material penetrating into the shaft groove. Such an approach is described in DE-A 23 45 017.

The pressure exerted by the spring-loaded hold-down device is often not sufficient to press the two joining parts against one another without a gap, which is particularly the case with hard and thick sheet metal is the case. The strength of the riveted joints is therefore differently. The same disadvantage occurs when the parts to be joined are different Show tolerances. Since the movement of the ram is controlled away, must Thickness tolerances can be compensated for by adjusting the height of the anvil.

The task is to design the stamping and embossing tool so that it is flawless Rivet connection between the parts to be joined is achieved.

This problem is solved with the features of claim 1. Advantageous Refinements can be found in the subclaims.

Fig. 1A und 1 B einen Schnitt durch den Hydraulikzylinder und die daran angeschlossenen Aggregate;

Fig. 2 eine Seitenansicht des Werkzeugs in Ausgangsstellung mit geschnittenem Kopf mit kurzem Mundstück;

Fig. 3 eine der Figur 2 entsprechende Darstellung mit gegen die Fügeteile anstoßendem Niederhalter;

Fig 4 einen Schnitt durch den Kopf beim Setzen des Niets und

Fig. 5 eine der Figur 4 entsprechende Darstellung beim Prägen der Fügeteile.

An embodiment is explained below with reference to the drawings. Show it:

1A and 1B show a section through the hydraulic cylinder and the units connected thereto;

2 shows a side view of the tool in the starting position with a cut head with a short mouthpiece;

3 shows a representation corresponding to FIG. 2 with the holding-down device abutting against the joining parts;

Fig. 4 shows a section through the head when setting the rivet and

5 shows a representation corresponding to FIG. 4 when embossing the parts to be joined.

The stamping and embossing tool has a hydraulic cylinder 1, in which two pistons 2, 3 are guided. The rivet needle 4 is connected to the upper piston 2, while with the lower piston 3, a press cylinder 5 is connected, which in Fig. 1st not shown press ram carries. With the upper piston 2 is still connected a hollow piston rod 6. The piston 2 has bores 7, which the space 8th Connect between the pistons 2, 3 to the inside of the piston rod 6. The cylinder 1 has a connection 9 which opens into the cylinder space above the piston 2. The inside of the piston rod 6 is connected to a further connection 10, while the cylinder space below the piston 3 is connected to a third connection 11.

Connected to port 9 is a first pressure cylinder 12 with which another Printing cylinder 13 can be connected, with which in turn a third printing cylinder 14 is connectable. The connection 10 is connected to an adjustable throttle 15, the is in turn connected to a variable-volume pressure chamber 16.

The sequence of operations is as follows: The piston 17 of the pressure cylinder 14 is initially himself in his left position. Take the pistons 18 and 19 of the pressure cylinders 12, 13 their right position as shown. This creates a hydraulic connection from the impression cylinder 14 via the impression cylinder 13 and the impression cylinder 12 to Connection 9. The throttle 15 is open, so that a direct connection between the Space 8, the holes 7, the hollow piston rod 6, the connection 10, the throttle 15th to the left side of the piston 20 of the pressure chamber 16. To the right side of the Piston 20 acts at a constant pressure.

After a rivet has been fed to the lower end of the rivet needle 4, which is there by means of Is kept under pressure, compressed air via the port 21, the pressure cylinder 14th fed, whereby the piston 17 is pressed to the right and pressure over the Printing cylinder 13 and the printing cylinder 12 is fed to the port 9, since the Connections between all printing cylinders are open. In room 8 between the Cylinders 2, 3 have a pressure determined by the pressure chamber 16. This pressure in Space 8 is greater than the pressure exerted by the pressure cylinder 14 on the upper side of the piston 2 acts. This ensures that both with oil supply to port 9 Pistons 2, 3 are moved down synchronously.

If, during this downward movement, the press die 25 hits the upper joining part 24A, a back pressure in the pressure cylinder 14 on the right side of the piston 17 built up. When a predetermined back pressure is reached, the pressure cylinder 13 activated, in which 22 compressed air is supplied via the connection there, the Piston 19 moved to the left. The connection between the pressure cylinder 14 and the pressure cylinder 13 closed and an oil pressure generated which is greater than the oil pressure in the room 8. The oil supplied from the pressure cylinder 13 to the connection 9 causes the piston 2 to approach the piston 3, the oil in the space 8 in the Pressure chamber 16 is conveyed and the piston 20 is shifted to the right.

The piston 2 has approached the piston 3 by a predetermined distance, which is greater than the length of the rivet, the pressure cylinder 12 is activated by Compressed air supply at port 23 of piston 18 is moved to the left. At this Movement, the connection between the cylinders 12, 13 is interrupted. from Pressure cylinder 12, oil is supplied to port 9 under high pressure. With Actuation of the pressure cylinder 12, the throttle 15 is activated, so that between a throttle resistor is built up to the connection 10 and the pressure chamber 16. This throttle resistance is adjustable.

The piston 3 thus has a high resistance, but due to the throttle resistance adjustable pressure, which causes the press ram 25 attached to the press cylinder 5 exerts a high hold-down force on the joining parts 24A, 24B, which is thus gap-free lie against each other, see position of Fig. 3. At the same time, the rivet 29 of the Rivet needle 4 pressed through the joining parts 24A, 24B and the rivet head into the generated Bore of the upper joining part 24A, see position according to FIG. 4.

At the end of its downward movement, the piston 2 sits on the piston 3, with which the Press ram 25 presses with high pressure on the upper joining part 24A and thus the Embossing lip 28 of the anvil 26 is pressed into the lower joining part 24B and the displaced Material penetrates into the shaft groove of the rivet 29. The stamping and embossing process is thus finished, see position according to FIG. 5.

The pistons 17, 18, 19 are returned to their starting position. The throttle 15 will be opened. The oil pressure in the pressure chamber 16 separates the two pistons 2, 3 from one another. At the same time, a pressure is built up below the piston 3 via the connection 11, so that both pistons 2, 3 are returned to their starting position.

The hydraulic cylinder 1 is connected to the tool frame via a C-bracket 23. The tool head comprises the rivet needle 4 and the ram 25, the one Has bore through which the rivet needle 4 is displaceable. The ram 25 is attached to the press cylinder 5. At the lower end of the rivet needle 4 is a Flanged valve body 30, the slide of the rivet 29 the lower end of the Rivet needle 4 feeds.

The press ram 25 has the function of a hold-down device. The to each other connecting joining parts are designated with 24A and 24B. They are on anvil 26 on this anvil 26 is provided with a bore 27 which is formed by an embossing lip 28 is surrounded.

Starting from the position shown in Figure 2, the rivet needle 4 and the ram 25 lowered into the position shown in Figure 3, in which the ram 25 the parts to be joined 24A and 24B presses against each other and against the anvil 26. Then the rivet needle 4, at whose lower end the rivet 29 is held, through the hole in the ram 25 moves, the rivet 29 being pressed into the joining parts 24A, 24B until the rivet head forms a flush surface with the surface of the joining part 24A. The punch slugs fall here through the bore 27. After the rivet 29 has been set, the press ram 25 presses with increased pressure against the joining part 24A. The embossing lip 28 penetrates around it around the lower end of the rivet shaft into the joining part 24B, material of the Joining part 24B is pressed into the shaft groove of the rivet 29.

Claims (7)

1. Punching and stamping tool with a rivet pin (4) which can be moved in a bore of a stamp die (25) for joining together workpieces (24A, 24B) by means of a rivet (29), in which, when the rivet pin (4) moves downwards, the rivet (29) is pressed into the workpieces (24A, 24B) and then the stamp die (25) generates a stamping force through which an anvil (26) causes the material of the workpiece (24B) resting on the anvil (26) to be deformed, whereby material is pressed into the groove in the shaft of the rivet (29), characterised in that a hydraulic cylinder (1) is provided with two pistons (2, 3), one piston (2) carrying the rivet pin (4) and the other piston (3) carrying the stamp die (5, 25), the chamber (8) between the pistons (2, 3) being connected to a variable-volume pressure chamber (16), the cylinder chamber which faces one piston (2) is connected to a pressure cylinder (12), and a control system is provided which, after a rivet (29) has been conveyed to underneath the rivet pin (4) and with the stamp die (25) resting on the upper workpiece (24A), activates one pressure cylinder (12) and interposes a throttle (15) between the chamber (8) between the pistons (2, 3) and the pressure chamber (16) and in so doing, to execute the punching process and to exert a downward clamping force through the stamp die (25) the pressure of the pressure cylinder (12) presses one piston (2) in the direction of the other piston (3) until, to execute the stamping process, one piston (2) is resting on the other piston (3).
2. Punching and stamping tool according to claim 1, characterised in that the throttle resistance of the throttle (15) is adjustable.
3. Punching and stamping tool according to claim 1 or 2, characterised in that one piston (2) has a hollow piston rod (6) which is connected to the throttle (15) and into which, through this one piston (2), bores (7) open which lead to the chamber (8) between the pistons (2, 3).
4. Punching and stamping tool according to one of claims 1 to 3, characterised in that a further pressure cylinder (13) is provided which can be connected to the cylinder chamber which faces the one piston (2), which generates a pressure which is less than that of the one pressure cylinder (12) but is greater than that in the pressure chamber (16), and when this is activated, the one piston (2) is pressed in the direction of the other piston (3) until the pistons (2, 3) are at a preset distance from each other, whereupon the cylinder chamber is then connected to the one pressure cylinder (12).
5. Punching and stamping tool according to claim 4, characterised in that a third pressure cylinder (14) is provided which can be connected to the cylinder chamber which faces the one piston (2), which generates a pressure which is less than that in the pressure chamber (16) and when this is activated, both pistons (2, 3) are pressed in the direction of workpieces to be joined (24A, 24B), until the stamp die (25) is in contact with the upper workpiece, upon which the cylinder chamber is then connected to the further pressure cylinder (13).
6. Punching and stamping tool according to one of claims 1 to 5, characterised in that the rivet pin (4) guided in the stamp die (25) has a bore running along the rivet pin (4) and which can be connected to a negative pressure source, which opens onto the tip of the rivet pin (4).
7. Punching and stamping tool according to one of claims 1 to 6, characterised in that in the region of the tip of the rivet pin (4) a slide housing (30) is arranged in which a slide is arranged which can be moved transversely to the rivet pin (4), which moves the rivet (29) to this tip.

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