DE1081853B - Method for producing hollow bodies open on one side by punching a block and then stretching out the hole in a push bench - Google Patents

Description

The invention relates to a method for producing hollow bodies open on one side by punching of a block and then extending the hole piece in a push bench, the starting workpiece when punching, an inside diameter that is larger than the clear dimension of the finished workpiece and is given a conical part for centering the push rod in the area of its hole end.

When proceeding in the sense of this method, the front end of the workpiece, in which it is centered on the mandrel, usually takes part in the ironing in the subsequent drawing process. The discovery of the inventive teaching previous investigations have led to the result that the processing performed in the area of the workpiece leading end Abstreckarbeit requires a disproportionately high peak force in bumping the hole piece by the drawing ring and also is often the cause of an eccentric position of the Luppenbohrung respect to the outer diameter. If, however, according to the teaching coveted for protection, the front end of the workpiece in the receiver of the punch press concentrically to its inner conical centering part is also formed conically on the outside in such a way that the pulling ring only engages the workpiece after it has completely or almost completely passed through the push pin centering area, the peak force when pulling the Luppe significantly lowered and its centric training promoted.

A conical shape of the lobes in question at their front end is on known oneself; however, the combination of this feature with the centering of the doll is on one conical front part of the mandrel when pushing the shell again.

An embodiment of the invention is shown in the drawings. It shows

Fig. 1 schematically the punching process,

Fig. 2 shows the pushing process.

The molding 1 is inserted into a die 2 and is pierced there with the punch 3 conically at the front and cylindrically over most of its length, the diameter of the cylindrical part of the piercer being greater than the clear width of the final hollow body. Experience has shown that the axis 4 of the punch 3 deviates from the axis 5 of the die and consequently the desired cavity. This deviation leads to an eccentricity e which cannot be avoided.

To cite a practical example, in the production of a hollow body with a final inner diameter of 123 mm, the cylindrical part of the front conical hole punch can be dimensioned with a diameter of 137.5 mm, which includes a grinding tolerance of 0.1 mm . The method of manufacture
hollow body open on one side

by punching a block
and then stretching out
of the hole piece in a push bench

Applicant:

Societe des Acieries de Pompey,
Pompey, Meurthe-et-Moselle (France)

Representative: Dipl.-Ing. B. Weir,

Dipl.-Ing. H. Seiler, Berlin-Grunewald, Lynarstr. 1,

and Dipl.-Ing. H. Stehmann, Nuremberg 2,

Patent attorneys

Claimed priority:
France 6 June 1956

Roland Paulmier, Caen, Calvados (France),
has been named as the inventor

on the other hand, the push pin 8 is given a diameter of 123.5 mm with a grinding tolerance of 0.05 mm. The difference of 0.5 mm in the diameter of the push rod and the finished hollow body represents the expansion tolerance. During the punching process following the punching process, the workpiece becomes 1 centered in its front part 11 on the front part of the push rod 8, the inner diameter 6 of the workpiece is larger than the diameter of the push pin. The workpiece is then pushed through the drawing ring 8 and reduced its inner and outer diameter.

The push pin 8 comes to a stop on the bottom 9 of the bore 6 and has exactly or approximately the shape of the corresponding section 11 of the conical end of the bore 6 over a length L.

Up to this point, what has been described reflects the state of the art.

The invention consists in that in the die 2 the hollow body has been formed conically on the outside in such a way that when the workpiece 1 is pushed through the ring 7, the latter only engages the workpiece when the conical centering area of the joint '"' - - ' S "M951WM8

thorns has passed the drawing ring 7. The workpiece 1 does not experience any ironing over a length L ' which essentially corresponds to the length L; Rather, this begins only behind the centering point of the mandrel and at the point where the difference between the inside diameter of the workpiece 1 and the outside diameter of the mandrel 8 can be felt.

A non-disruptive residual eccentricity e then only remains in the conical end area of the workpiece 1.

Claims (1)

PATENT CLAIM: Method of manufacture term workpiece larger inner diameter and for centering the push pin in the area of his Hole end receives a conical part, characterized in that the front workpiece end in the receiver (2) of the punch press concentric to its inner conical centering part outside is also formed conically in such a way that the drawing ring (7) only after complete or almost engages the workpiece (1) when it completely passes through the push pin centering area (L). Considered publications:
German Patent Nos. 740501, 670 575;
British Patent Nos. 655 532, 627 825, more open on one side Hollow body by punching a block and then extending the hole piece in a 15 102 898; Push bench, with the starting workpiece in U.S. Patents No. 2,642,647, 2,278,325, Punch a hole opposite the clear dimension of the fer- 2 248 002. 1 sheet of drawings © 009 510/1 «5, W.