GB2047146A

GB2047146A - Flattening or shaping sheet metal parts

Info

Publication number: GB2047146A
Application number: GB8003344A
Authority: GB
Original assignee: Walter Eckold GmbH and Co KG Vorrichtungs und Geraetebau
Current assignee: Walter Eckold GmbH and Co KG Vorrichtungs und Geraetebau
Priority date: 1979-02-02
Filing date: 1980-01-31
Publication date: 1980-11-26
Also published as: JPS55103220A; CH644286A5; ES488181A1; GB2047146B; BE881501A; FR2447759B1; ATA15680A; DE2903929A1; IT1128002B; IT8067139A0; FR2447759A1; AT369293B

Abstract

In a process for flattening or curving a sheet metal part (3) by means of stamping, the part is placed between two dies (4, 6) one (6) of which has a surface pattern, and the other (4) of which has a plane surface, with the face of the sheet metal part to be made less convex or more concave adjacent the plane die (4). The projected surface area of the patterned die (6) is substantially smaller than that of the sheet metal part (3) to be corrected. <IMAGE>

Description

SPECiFICATION Process for correcting the shape of sheet metal parts, device for carrying out the process and use of the process The invention relates to a process for correcting the shape of sheet metal parts.

It is known to render uneven sheet metal parts plane by so-called flat stamping. The process is described under the title "Flach- und Richtprägen, Nachschlagen" in "Werkstattblatt428 Gruppe D", published by Carl Hanser Verlag, Munich 1967. The process basically consists of pressing the sheet metal part to be flattened between two dies both of which are either plane or have a surface pattern in that pyramid-shaped projections project from the plane base face of a die. In the latter case, the points of the projections should rest against each other, that is to say, there should be no staggering parallel to the workpiece. The author observes that both sides of the piece of sheet metal have to be subjected to corrective stamping.

The problem of the invention is to provide a process having the features mentioned in the precharacterising clause of Patent Claim 1, with which the shape of sheet metal parts having considerably larger dimensions than the die face can be corrected.

The expression "correcting the shape" is used herein to mean that a sheet metal part which is in any way distorted is either planished or given a definite curved shape, that is to say, "bowed".

The solution to this problem is given in the characterising part of Patent Claim 1. It has been found, surprisingly, that if the face of the die is substantially smaller than the sheet metal part and if one die is plane and the other is provided with a surface pattern, distortions can be removed from the sheet metal parts by allowing the patterned die to act on the concave surfaces and only on these, the convex surfaces corresponding to the concave surfaces being adjacent the plane die. Accordingly, of course, intentional curves can be produced in originally flat sheet metal parts, for example, circular knives, by allowing the surface-patterned die to act on the side which will later be convex.

Embodiments of devices for carrying out the process are described below with reference to the accompanying drawings.

Figures 1 and 2 show in side view and in plan view, respectively, a hydraulic press in which the device is clamped when the sheet metal part is being corrected, Figures 3 to 10 show four different patterns for the surface-patterned die, each odd-numbered Figure showing the side view and the subsequent evennumbered Figures showing the plan view of the patterned surface, and Figures 11 to 14 are schematic representations of possible uses of the process.

The device shown in Figure 1 comprises a press frame 1 of which the upper die 2 is hydraulically movable by means of duct 16 and cylinder 17 in the direction of the arrow 15. The sheet metal part 3 to be machined is disposed on the plane lower die 4 which may be larger in the direction parallel to the workpiece than the upper die but is always substantially smaller than the actual workpiece at least in a surface direction.

Figures 3 to 10 relate in each case to the surface pattern of the upper die which is preliminarily designated "6" in Figures 1,2, and 3.

The embodiment shown in Figures 3 and 4 consists of a regular grid of pyramid-shaped projections 6 which project from the plane base 7 face of the upper die 2. This type of die is designed especially for correcting workpiece having a substantially rectangular outline.

The embodiment shown in Figures 5 and 6 is used primarily for correcting sheet metal parts having a round outline. In this case, a flat recess 8 is formed in a cylindrical die member 2' which recess is filled with balls 10. The balls are preferably fixed by glueing; their diameter 9 is of course greater than the depth 11 of the edge 12 which defines the recess 8.

According to Figures 7 and 8, the upper die 2" has on its working face parallel cutting edges 13 which, as shown in Figures 9 and 10, may be interrupted by transverse grooves 14, it being possible for the cutting edges 13 to be offset with respect to each other by half a spaces/2 on both. sides of each groove 14, as shown.

The embodiment having continuous cutting edges 13 is preferably used for straightening elongated strips 20 of sheet metal, the cutting edges acting on the workpiece transversely to the direction of elongation. This is shown in Figure 11. Figure 12 shows how, with the aid of the embodiment shown in Figures 5 and 6, a bulge 21 in the workpiece is flattened.

Figure 13 shows the use of the die construction shown in Figures 9 and 10, for the intentional bending of a bar 22, and Figure 14 shows the complete curving or bowing of a circular knife 23.

For this purpose, it is possible to use a die construction in which the surface-patterned die has an annular outline. Arrows "P" indicate the direction of relative movement of the dies.

Preferably, at least the projections of the die are made of hard metal.

1. Process for correcting the shape of sheet metal parts by means of corrective stamping between two dies, oneof which has a surface pattern, characterised in that the sheet metal part to be corrected is placed with its convex side on the other die which has a plane surface and is machined only at selected places by means of the surface-patterned die, the surface area of which die is substantially smaller than that of the sheet metal part to be corrected.

2. Device for carrying out the process according to claim 1, characterised in that the surfacepatterned die has parallel cutting edges projecting from a plane base face.

3. Use of the device according to claim 2 for flattening or transversely curving sheet metal parts

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECiFICATION Process for correcting the shape of sheet metal parts, device for carrying out the process and use of the process The invention relates to a process for correcting the shape of sheet metal parts. It is known to render uneven sheet metal parts plane by so-called flat stamping. The process is described under the title "Flach- und Richtprägen, Nachschlagen" in "Werkstattblatt428 Gruppe D", published by Carl Hanser Verlag, Munich 1967. The process basically consists of pressing the sheet metal part to be flattened between two dies both of which are either plane or have a surface pattern in that pyramid-shaped projections project from the plane base face of a die. In the latter case, the points of the projections should rest against each other, that is to say, there should be no staggering parallel to the workpiece. The author observes that both sides of the piece of sheet metal have to be subjected to corrective stamping. The problem of the invention is to provide a process having the features mentioned in the precharacterising clause of Patent Claim 1, with which the shape of sheet metal parts having considerably larger dimensions than the die face can be corrected. The expression "correcting the shape" is used herein to mean that a sheet metal part which is in any way distorted is either planished or given a definite curved shape, that is to say, "bowed". The solution to this problem is given in the characterising part of Patent Claim 1. It has been found, surprisingly, that if the face of the die is substantially smaller than the sheet metal part and if one die is plane and the other is provided with a surface pattern, distortions can be removed from the sheet metal parts by allowing the patterned die to act on the concave surfaces and only on these, the convex surfaces corresponding to the concave surfaces being adjacent the plane die. Accordingly, of course, intentional curves can be produced in originally flat sheet metal parts, for example, circular knives, by allowing the surface-patterned die to act on the side which will later be convex. Embodiments of devices for carrying out the process are described below with reference to the accompanying drawings. Figures 1 and 2 show in side view and in plan view, respectively, a hydraulic press in which the device is clamped when the sheet metal part is being corrected, Figures 3 to 10 show four different patterns for the surface-patterned die, each odd-numbered Figure showing the side view and the subsequent evennumbered Figures showing the plan view of the patterned surface, and Figures 11 to 14 are schematic representations of possible uses of the process. The device shown in Figure 1 comprises a press frame 1 of which the upper die 2 is hydraulically movable by means of duct 16 and cylinder 17 in the direction of the arrow 15. The sheet metal part 3 to be machined is disposed on the plane lower die 4 which may be larger in the direction parallel to the workpiece than the upper die but is always substantially smaller than the actual workpiece at least in a surface direction. Figures 3 to 10 relate in each case to the surface pattern of the upper die which is preliminarily designated "6" in Figures 1,2, and 3. The embodiment shown in Figures 3 and 4 consists of a regular grid of pyramid-shaped projections 6 which project from the plane base 7 face of the upper die 2. This type of die is designed especially for correcting workpiece having a substantially rectangular outline. The embodiment shown in Figures 5 and 6 is used primarily for correcting sheet metal parts having a round outline. In this case, a flat recess 8 is formed in a cylindrical die member 2' which recess is filled with balls 10. The balls are preferably fixed by glueing; their diameter 9 is of course greater than the depth 11 of the edge 12 which defines the recess 8. According to Figures 7 and 8, the upper die 2" has on its working face parallel cutting edges 13 which, as shown in Figures 9 and 10, may be interrupted by transverse grooves 14, it being possible for the cutting edges 13 to be offset with respect to each other by half a spaces/2 on both. sides of each groove 14, as shown. The embodiment having continuous cutting edges 13 is preferably used for straightening elongated strips 20 of sheet metal, the cutting edges acting on the workpiece transversely to the direction of elongation. This is shown in Figure 11. Figure 12 shows how, with the aid of the embodiment shown in Figures 5 and 6, a bulge 21 in the workpiece is flattened. Figure 13 shows the use of the die construction shown in Figures 9 and 10, for the intentional bending of a bar 22, and Figure 14 shows the complete curving or bowing of a circular knife 23. For this purpose, it is possible to use a die construction in which the surface-patterned die has an annular outline. Arrows "P" indicate the direction of relative movement of the dies. Preferably, at least the projections of the die are made of hard metal. CLAIMS

3. Use of the device according to claim 2 for flattening or transversely curving sheet metal parts which have substantially smaller dimensions in the direction parallel to the cutting edges than in the direction perpendicular there-to.

4. Device for carrying out the process according to claim 1, characterised in that the surface patterned die has pyramid-shaped projections arranged in a grid and projecting from a plane base face.

5. Use of the device according to claim 4 for flattening or bowing sheet metal parts of substantial ly rectangular outline.

6. Device for carrying out the process according to claim 1, characterised in that the surface patterned die has spherical projections projecting - from a plane base face.

7. Use of the device according to claim 6 for flattening or bowing sheet metal parts having a substantially round outline.

8. Use of the device according to claim 6 for completely curving circular knives.

9. Device according to one of claims 2, 4 or 6, characterised in that the projections or cutting edges are provided over the entire die face.

10. Device according to one of claims 2, 4 or 6, characterised in that the projections are provided only on a part of the die face.

11. Device according to claims 2 and 10, char acterised in that the cutting edges are interrupted by transverse grooves.

12. Device according to claim 10, characterised in that the projections are provided only in the peripheral region of the die face.

13. Device according to claim 6, characterised in that a plurality of contiguous balls are stuck into a flat recess in the working face of the die.

14. Device according to one of claims 2, 4, 6, and 9 to 13, characterised in that the projections or cutting edges consist of hard metal.

15. A process for shaping a sheet metal part, including the step of stamping the sheet only at selected places between two dies one of which has a surface pattern and the other of which has a plane surface, the projected surface area of the patterned die being substantially smaller than that of the sheet metal part to be corrected.

16. A process substantially as herein described with reference to and as illustrated by Figures 1 and 2 of the accompanying drawings.

17. A process as claimed in claim 16 and sub stantially as herein described with reference to and as illustrated by Figures3 and 4,or by Figures 5 and6, or by Figures 7 and 8 or by Figures 9 and 10 of the accompanying drawings.

18. A process as claimed in claim 16 and sub stantially as herein described with reference to and as illustrated by Figure 11, or by Figure 12, or by Figure 13, or by Figure 14 of the accompanying drawings.

19. An apparatus substantially as herein de scribed with reference to and as illustrated by Figures 1 and 2 of the accompanying drawings.

20. An apparatus as claimed in claim 19 and substantially as herein described with reference to and illustrated by Figures 3 and 4, or by Figures 5 and 6, or by Figures 7 and 8 or by Figures 9 and 10 of the accompanying drawings.