DE1249805B - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

PATENT LETTERING

Int. Cl .:

German class:

Number:

File number:

Registration date:

Display day:

Issue date:

B21d

7C-10

1249 805
A34106Ib / 7c
March 2, 1960
September 14, 1967
March 21, 1968

The patent specification corresponds to the patent specification

The invention relates to a hydraulically driven press with a cutting punch bearing Press ram, in which a cylinder is centrally arranged which contains a drive pin; which drives at least one ejector penetrating the stamp and its base.

This known press is not suitable for fineblanking, as it is a necessary fixation of the too processed sheet metal by a hold-down is missing and this fixation is essential for fineblanking necessary is. This fine blanking, which is also called fine blanking, results in high-precision die-cut parts and cut surface quality. With a fine punching press, punched parts can be made from sheet metal and foils made of metal, non-metal or plastic cut out and, if necessary, perforated will.

The high accuracy and cut surface quality in fineblanking is only achieved if the Punched strips during the punching process in the entire area adjacent to the punch with high Precision is recorded.

Known fine blanking presses for cutting out and punching workpieces from sheet metal have both a hold-down device surrounding the cutting punch as well as at least one cutting punch and the pusher penetrating its base, the hold-down device and the pusher each have a separate drive. When fine blanking must also with complex and large areas Die-cut the pressure of the hold-down device at least almost anywhere on the work surface be the same size so that the quality of the cut is not adversely affected. With the known Fine blanking presses, the drive means for the hold-down device are arranged around the press ram, see above that the pressure is only transferred peripherally to the hold-down device. This creates disadvantageous Bending loads on the hold-down device, which make it possible to achieve cutting precision beyond a certain level make beyond impossible.

Hold-down devices and ejectors of various types are both individually and together otherwise known in presses, including those that penetrate the pressure bolts through the die base are supported. To press the hold-down device against the metal strip to be processed with great force to be able to, it is known that the hold-down device not with elastically pretensioned springs, but operated hydraulically. For this purpose, drive means for the hold-down device are necessary. But there are drive means for the ejector are also necessary.

Hydraulically driven press for
Fineblanking

Patented for:

Aknatic AG, Glams (Switzerland)
Representative:

Dipl.-Ing. C. Stoepel, patent attorney,
Landau (Palatinate), Am Schützenhof

Named as inventor:

Heinrich Schmid, Rapperswil (Switzerland)

Claimed priority:

Switzerland of March 4, 1959 (70 314)

The object underlying the invention is to pieces 5, a fine blanking press for cutting or piercing tool "known from the aforementioned press, particularly to provide from sheet metal, in which the aforementioned disadvantages construction expense and adverse stress are not present with respect to.

This object is achieved according to the invention in that a known hold-down device is provided which surrounds the stamp and penetrates the stamp base and is also driven by the piston of the ejector, the combination of all features making up the invention. In a further embodiment of the invention, the hold-down device is guided in a retaining ring which is fastened to the stamp base and which engages under the hold-down device.
In such a press there is only one drive for the ejector and the hold-down device. This results in a simple structure and advantageous stress on the components even at high working pressures. The fine blanking press also has these advantages when using a punching tool with several ejectors, which can be easily accommodated spatially and structurally simple.

Bending presses are known in which the press ram and the hold-down device are connected to a single hydraulic one Are connected to the system and a drive piston for the hold-down device is located inside the Pressbear is located. In the known presses lies

"09 52" / 32

Claims (2)

but the drive piston for the hold-down device is not centrally located within the press ram, so that disadvantageous bending stresses occur in the area of the hold-down device. The drawing shows an embodiment of the subject matter of the invention with only one ejector for cutting out and punching an annular disc. It shows F i g. 1 an upper part of a punching tool arranged on the press ram in longitudinal section and FIG. 2 shows a plan view of a punched strip with a punched item. A press ram 1 can be raised and lowered in a machine frame, not shown, by hydraulic actuation. The press ram 1 carries a stamp bridge 2 as a stamp base, to which a cutting stamp 3 is fastened by means of screws 4. In the longitudinal axis of the press ram 1 there is a cylinder 5 in which a piston 6 can be raised and lowered by hydraulic actuation. The punch 3 ao and the punch bridge 2 are penetrated by an ejector 7 designed as a bolt. The latter also serves as a counter-holder for a punch, not shown, mounted on a press plate of the press and used for punching out the washer 8. The cutting punch 3 is surrounded by a hold-down device 9, which is in operative connection with the piston 6 by means of pressure bolts 10. A retaining ring 12, which engages under an annular shoulder 13 of the hold-down device 9, is fastened to the stamp bridge 2 by means of screws 11. This retaining ring 12, on the one hand, limits the stroke of the hold-down device 9 and, on the other hand, pulls it along with the upward movement of the press ram 1. The punch bridge 2, the punch 3 and the retaining ring 12 are thus rigidly attached to the press ram 1. The piston 6, the pressure bolts 10 and the hold-down device 9 can be displaced relative to the components 1 to 3 and 12. In Fig. 1, the two end positions of the components movable with respect to the press ram are shown with respect to the longitudinal center axis of the tool. The in F i g. 1, arranged on the press ram 1, the upper tool part is used to punch out an annular disc 14 from a punched strip 15 (FIG. 2). The hold-down 9 has a sharp-edged, ring-shaped prong 16 on its underside, which is pressed concentrically to the punch 3 during the punching process along a line 17 into the punching strip 15. The mode of operation of the tool is as follows: At the beginning of the punching process, the entire tool moves according to FIG. 1 as a result of the hydraulic actuation of the press ram 1 downwards and approaches the punched strips 15 resting on a support, not shown, of the press, the piston 6, the pressure bolts JO1, the ejector 7 and the hold-down device 9 in their lowest end position according to the right-hand side in F i g. 1 are located. After the tool strikes the punched strip 15, the latter initially opposes the hold-down device 9 and the ejector 7, which in this position serves as a counter-holder, a resistance. Due to the further lowering of the tool by the hydraulic loading of the press ram 1, on the one hand the cutting punch 3 is pressed into the punching strip 15 and, on the other hand, a hydraulic pressure is built up on the piston 6. The prong 16 of the holding-down device 9 is pressed into the punching strip 15 according to the line 17 and the cutting punch 3 penetrates the punching strip 15 and cuts the outer contour of the disc 14. During this process, the punch (not shown, located in the lower part of the press) has the washers 8 punched out upwards, on which the bolt 7 bears under the influence of the pressure from the piston 6. In the lower end position of the tool shown in FIG. 1, the parts 6, 7, 9 and 10 movable relative to the press ram 1 are in the upper end position according to the left-hand side in FIG. 1., Now the upward movement of the ram 1 begins, the hydraulic actuation increasing the pressure above the piston 6 and the piston 6 pushing the pressure pin 10, the ejector 7 and the hold-down 9 back into the lower end position. The hold-down 9 serves as a stripper for the punched strip 15. The ejector 7 pushes the washer 8 out of the cutting punch 3. The retaining ring 12 takes the hold-down 9 with the upward movement of the press ram 1, and the upper tool part goes back up to its starting position. Patent claims: 1. Hydraulically driven press with a press ram carrying the cutting punch, in which centrally a cylinder is arranged which contains a drive piston, which at least drives an ejector penetrating the stamp and its base, characterized in that for cutting and Punching by fine cutting of workpieces (14), in particular made of sheet metal, a pressure bolt (10), known per se, surrounding the punch (3) and penetrating through the punch support (2) supported hold-down device (9) is provided, which is also driven by the piston (6) of the ejector (7). 2. Press according to claim 1, characterized in that the hold-down device (9) is guided in a retaining ring (12) which is fastened to the stamp base (2) and engages under the hold-down device. Publications considered: Swiss Patent No. 240875;
U.S. Patent Nos. 2,173,358, 2,214,635;
"Werkstatt und Betrieb", 1955, p. 327. 1 sheet of drawings 709 647/183 9.67 O Bundesdruckerel Berlin