GB2340425A

GB2340425A - Die support for a press tool

Info

Publication number: GB2340425A
Application number: GB9817503A
Authority: GB
Inventors: John Leslie Broad
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1998-08-13
Filing date: 1998-08-13
Publication date: 2000-02-23
Also published as: DE69901188D1; GB9817503D0; EP1104342B1; EP1104342A1; WO2000009276A1; DE69901188T2

Abstract

A power press (10, Fig. 1) has a lower press tool 12. A shaped die 20 is set at the required height using a spacer assembly 22. The spacer assembly is formed by interengaged spacer plates 23, 24 between support plates 21a, 21b. The spacer plates may be identical and are formed by laser cutting from sheet steel. This system reduces the time and effort required to form a spacer to suit a particular press job.

Description

A Press Tool This invention relates to a press tool and in particular to a

means for spacing a die of the press tool from an operating surface of a press.

It is well known to use a cast iron spacer to allow a panel or blank to be located at the correct height between the operating surfaces of a press. This cast spacer is both time consuming and expensive to produce as a pattern has to first be produced for the spacer and this pattern then has to be used to cast the spacer.

After casting the surfaces of the spacer that abut the operating surfaces of the press and the rear surface of the die have to be machined. It is therefore not unusual for the manufacturing process to take 6 to 8 weeks from conception to delivery of the 10 finished spacer.

In addition such a spacer is relatively heavy and is not easy to manipulate when attaching it to the press.

It is an object of this invention to provide an improved press tool that is cheaper and quicker to manufacture.

According to the invention there is provided a press tool comprising a die and a support means for the die, the support means co mprising a number of interengaged spacer plates, each of the spacer plates having a longitudinal axis and a transverse axis and two longitudinal edges extending along the length of the plate, the two spacer plates being arranged to interengage to form a matrix having upper and lower edges corresponding to the edges of the spacer plates.

Preferably, the dimension of each of the spacer plates may be greater along the 5 longitudinal axis than it is along the transverse axis extending between the two edges.

There may be a support plate interposed between the matrix and the die.

Preferably, each of the spacer plates may have a number of slots extending transversely from one of said longitudinal edges.

The slots in the plates may be interengaged to connect the plates together to form 10 the matrix.

Preferably, some of the spacer plates may have slots extending from the lower edge and some of the spacer plates may have slots extending from the upper edge.

Preferably, the spacer plates may be held in said interengagement by welding.

Advantageously, the spacer plates may be formed by laser cutting from a sheet of 15 material.

Advantageously, all of the spacer plates may be identical before assembly.

Preferably, at least one of the spacer plates may have a number of lugs formed on one edge thereof for engagement with recesses in the support plate.

The invention will now be described by way of example with reference to the accompanying drawing of which:- Fig. 1 is a side view of a press having upper and lower press tools according to the invention; Fig.2 is a pictorial view of a press tool according to the invention; and Fig.3 is a pictorial view of a second embodiment of a press tool according to the invention.

With reference to Fig. 1 there is shown a press in the form of a hydraulic power press 10 to which is secured an upper press tool 11 and a lower press tool 12.

The upper press tool 11 has a hydraulic ram 14 to which is attached a flat plate 19 forming an upper operating surface. An upper die 16 is attached to the upper operating surface by means of a support means in the form of a spacer matrix 17 and 15 two support plates 18.

The lower press tool 12 has a bolster 15 forming a lower operating surface. A lower die 20 is attached to the bolster 15 by means of a support means in the form of a spacer matrix 22 and two support plates 21.

As is normal practice threaded fasteners (not shown) are used to attach the press tools 11 and 12 to the press 10.

With particular reference to Fig.2 there is shown in greater detail the lower press tool 12.

The press tool 12 comprises of a lower die 20 supported by a support means in the form of the support matrix 22. The support matrix 22 is formed by a number of interengaged spacer plates 23, 24. Each of the spacer plates 23, 24 has a longitudinal axis L-L and a transverse axis T-T. The transverse axis T-T being arranged to lie in use parallel to the axis of movement of the ram 14 and the longitudinal axis L-L being arranged to lie in use at right angles to the axis of movement of the ram 14.

All of the plates 23, 24 are identical and are produced by laser cutting from a sheet of steel of required thickness. The thickness and number of the spacer plates will depend upon the load to which the press tool is subjected to in use, but generally the plates will be between two millimetres and twenty millimetres in thickness.

The upper spacer plates 23 each have an upper edge 25 and a lower edge 27 and two slots 29 extending inwardly from the lower edge for approximately half the transverse width of the spacer plate 23. The width of each of the slots 29 is slightly greater than the thickness of the lower support plates 24. The upper edge 25 of each of the upper plates 23 each has two lugs 31 extending therefrom for engagement with corresponding recesses in the form of apertures 33 in a top support plate 21a. The lugs 31 are used to locate the spacer plates 23 relative to the upper support plate 21a. As can be seen each of the spacer plates 23, 24 is considerable longer in the longitudinal direction along the axis L-L than is the width in the transverse direction along the axis T-T. This ensures that the spacer plates, when assembled form a matrix or lattice structure, are very resistant to compressive loads applied parallel to the axis T-T and do not readily buckle or collapse.

The matrix has upper and lower edges corresponding to the upper and lower edges of the spacer plates 23, 24.

The lower support plates 24 each have an upper edge 26 and a lower edge 28 and two slots 30 extending inwardly from the upper edge 26 for approximately half the transverse width of the spacer plate 24. The width of each of the slots 30 is slightly greater than the thickness of the upper support plate 23. The lower edge 28 of each of the lower plates 24 each has two lugs 32 extending therefrom for engagement with 20 corresponding recesses in the form of apertures 34 in a bottom support plate 21b.

The lugs 32 are used to locate the spacer plates 24 relative to the lower support plate 21b.

To form the spacer matrix the upper and lower spacer plates 23 and 24 are brought together so as to engage the slots 29 with the slots 30. The plates are pressed together until the lower edges 27 of the upper spacer plates 23 lies flush with the lower edges of the lower spacer plates 24. The upper and lower spacer plates are then held together by tack welding.

The upper and lower support plates 21a and 21b are then located in place by means of the lugs 31, 32 and recesses 33, 34 and secured to the matrix 22 by tack welding. The lower die 20 is then fastened to the upper support plate 21a by threaded fasteners (not shown).

It will be appreciated that the terms upper and lower have been used herein for ease of explanation and if related to the upper tool would be reversed. For example in that case the upper die 11 is fastened to the lower support plate. Similarly, it will be appreciated that if an upper spacer plate 23 is rotated through 180 degrees it becomes a lower spacer plate and the reference to upper and lower edges is then reversed. Similarly if a lower spacer plate 24 is rotated through 180 degrees it becomes an upper spacer plate 23 both plates being identical except for their respective orientations.

It is not necessary that the upper and lower spacer plates are identical the thickness of the plates could be different but the width of the slots 29 or 30 would then need to correspond to the relevant thickness of the opposite plate.

It will be appreciated that a matrix structure as described above is both relatively light and easy to fabricate and if produced by laser cutting the spacer plates and the support plates little or no additional machining is required.

Although the invention has been described with reference to the use of four spacer plates is is not limited to this number of plates. In practice the number of plates required will be determined by the strength required to resist the load applied to the tool during its use in the power press. In some cases more plates may be required locally or the thicknes of the plates in different positions may be different to account for uneven loading of the tool.

In addition it will be appreciated that the support plates could be so produced as to form part of the tool having apparatus to effect piercing or bending of the metal directly attached to it or could be a die block.

It will be further appreciated that as shown in Fig.3 the size of the spacer plates 123, 124 are of different widths to provide a tool with several different heights.

In the press tool shown there are three support plates 121a, 121b and 121c. the height of the second support plate 121above the first support plate 121b being less than the height of the third support plate 121c above the first support plate 121b.

A heel box 128 is formed from the spacer plates 123, 124 and wear faces 129 are bolted to the upwardly extending ends of the spacer plates 123, 124.

The third support plate 121c has a number of threaded apertures formed therein to which piercing and trimming tools can be attached.

Claims

-9CLAIMS

1. A press tool comprising a die and a support means for the die, the support means comprising a number of interengaged spacer plates, each of the spacer plates having a longitudinal axis and a transverse axis and two longitudinal edges extending along the length of the plate, the two spacer plates being arranged to interengage to form a matrix having upper and lower edges corresponding to the edges of the spacer plates.

2. A press tool as claimed in Claim I in which the dimension of each of the spacer plates is greater along the longitudinal axis than it is along the transverse axis extending between the two edges.

3. A press tool as claimed in Claim 1 or in Claim 2 in which there is a support plate interposed between the matrix and the die.

4. A press tool as claimed in any of Claims 1 to 3 in which each of the spacer plates has a number of slots extending transversely from one of said longitudinal edges.

5. A press tool as claimed in Claim 4 in which the slots in the plates are interengaged to connect the plates together to form the matrix.

6. A press tool as claimed in Claim 5 in which some of the spacer plates have slots extending from the lower edge and some of the spacer plates have slots extending from the upper edge.

7. A press tool as claimed in any of Claims I to 6 in which the spacer plates are held in said interengagement by welding.

8. A press tool as claimed in any preceding claim in which the spacer plates are formed by laser cutting from a sheet of material.

9. A press tool as claimed in any preceding claim in which all of the spacer plates are identical before assembly.

10. A press tool as claimed in any of Claims 1 to 9 in which at least one of the spacer plates has a number of lugs formed on one edge thereof for engagement with recesses in the support plate.

11. A press tool substantially as described herein with reference to the accompanying drawing.