EP2411168B1 - Stamping method - Google Patents

Description

The invention relates to a stamping method for producing a bushing in a planar sheet-metal workpiece with both sides outwardly directed collar of a flat sheet-metal workpiece.

It is known a method for producing a sheet metal passage and a corresponding sheet metal part with sheet metal passage, DE 197 46 477 A1 , which extends on one side of a sheet.

A disadvantage of such a sheet metal passage is in particular that if it is introduced into a several millimeters thick sheets and the resulting through hole is to be used as a bearing seat for a shaft bearing, that only a single-ended force can be introduced into the sheet. However, in order to accommodate permanently high bearing forces, the sheet must be dimensioned thick accordingly, which adversely affects the overall weight and cost of a device constructed therewith.

Also known is a battery lid with a projection around a through hole and its manufacturing method, EP 2 043 178 A1 However, the projection extends only asymmetrically in an inward or outward direction.

Another known method involves forging a coupling housing from a solid block of metal, US 2004/250593 A1 used in a forging press using several different forging dies takes place in several separate steps and at a material temperature of several 100 ° C required for plastic deformation.

Furthermore, a stamping method for producing a chainring is known, DE 10 2007 005 847 A1 , with the aid of a flat chainring can be generated, which has no protruding bushings.

The object of the invention is to provide a stamping method with which a collar with through-hole can be produced on both sides of a workpiece in a single workstation.

The solution to this problem results from the fact that in the first process step, a pressure plate and a counter-pressure plate with cylindrical recesses with identical inner contours and with each other to the recesses mutually facing beads include the intermediate workpiece and press on both sides a circumferential groove therein, with a lower punch and an upper punch a punch with each cylindrical cross sections are the same and with the inner contours of the recesses matching inner contours are guided therein, which also include the workpiece, so that behind the groove a first, both sides circumferential thickening of the sheet is produced. The recesses and the punch can optionally have circular cylindrical, oval or polygonal cross-sectional contours.

In a second method step, the lower punch and the counter-pressure plate move upwards, wherein the base plate remains relative to the lower punch and the pressing force between the pressure plate and the counter-pressure plate are maintained, so that the distance between the lower punch and upper punch is reduced and the volume of the workpiece located therebetween to the outside pressed and the double-sided circumferential thickening is increased.

In a third method step, in which the pressure force of the pressure plate and the counter-holding force of the lower punch is maintained, the upper punch moves first down and presses there again another part of the volume of the workpiece to the outside and brings so the double-sided circumferential thickening to its final dimension, wherein the workpiece is punched out with continued movement of the upper punch and then removed after moving apart of the punch and plates from the punch.

With this method, a two-sided sheet metal passage or a double-sided collar can be introduced into a metal sheet which, unlike single-sided passes, allows a symmetrical introduction of force into the workpiece.

In an intermediate step between the second and third process step either a function reversal can take place in which the counter-pressure plate on a support plate firmly resting as a die and the lower punch acts as a counter-holder, said function reversal by a mechanical, electrical, hydraulic, pneumatic or other changing device in the Punching can be done.

In a preparatory step, the workpiece can also be provided with a pre-hole, which significantly reduces the forces required for deformation.

The sheet-like workpiece produced by the punching process several millimeters thick is then provided on both sides with a circumferentially tightened collar in which a cylindrical through hole punched and pressed in the transition from the collar to the workpiece a circumferential groove.

It is particularly advantageous on the workpiece according to the invention that the collar has the same height on both sides, so that a symmetrical introduction of force into the metal sheet is possible. The workpiece produced by the punching method according to the invention further has a through hole with an inner contour with such a good and dimensionally accurate wall quality that it can be used eg as final dimensions for the seat of an outer ring of a shaft bearing to be inserted therein, without the through hole having to be further processed. Deviating from the circular cylindrical Qüerschnittsform cross-sectional shapes of the through hole are also displayed.

Fig. 1

den ersten Verfahrensschritt,

Fig. 2

den zweiten Verfahrensschritt,

Fig. 3

den Zwischenschritt zwischen Verfahrensschritt 2 und 3,

Fig. 4

den dritten Verfahrensschritt und

Fig. 5

einen Schnitt durch ein Blech mit dem beidseitig eingebrachten Kragen.

The process sequence will be described in more detail below with reference to the drawings. Show it:

Fig. 1

the first process step,

Fig. 2

the second process step,

Fig. 3

the intermediate step between process steps 2 and 3,

Fig. 4

the third step and

Fig. 5

a section through a sheet with the collar introduced on both sides.

Claims (4)

1. Stamping method for producing a bushing in a planar workpiece (6) in sheet form, with a collar (9) directed outwardly on both sides, characterized in that, in the 1 st method step, a contact pressure plate (3) and a counter pressure plate (2), each having cylindrical recesses with identical inner contours having beads facing one another around the recesses, enclose the workpiece (6) and press a groove into it on both sides, wherein a lower die (1) and an upper die (4), each having cylindrical cross sections of the same inner contours that coincide with the inner contours of the recess, are guided in said groove and likewise enclose the workpiece (6), so that behind the groove (11) a first peripheral thickening is created on both sides of the workpiece (6), in the 2nd method step the lower die (1) and the counter pressure plate (2) are moved up, wherein the counter pressure plate (2) remains back in relation to the lower die (1) and the pressing force between the contact pressure plate (3) and the counter pressure plate (2) is maintained, so that the distance between the lower die (1) and the upper die (4) is reduced and the volume located in between is forced outwards, thereby enlarging the peripheral thickening on both sides, and in the 3rd step, while maintaining the pressing force of the contact pressure plate (3) and the counter retaining force of the lower die (1), the upper die (4) first forces part of the volume of the workpiece (6) downwards and outwards and enlarges the peripheral thickening on both sides to its final dimensions, and the workpiece (6) is subsequently punched out in the same method step.
2. Stamping method according to Claim 1, characterized in that, as an intermediate step between the 2nd method step and the 3rd method step, a functional reversal takes place, in which the counter pressure plate (2) rests securely on a supporting plate (5) and thus acts as a cavity plate and the lower die (1) acts as a counter holder.
3. Stamping method according to one of the preceding claims, characterized in that, as a preparational step before the 1 st method step, a preliminary hole (8) is stamped into the workpiece (6).
4. Stamping method according to one of the preceding claims, characterized in that the functional reversal in the intermediate step is performed by a changing device in the stamp.

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