GB2403451A

GB2403451A - Die securing block registered to support plate

Info

Publication number: GB2403451A
Application number: GB0315416A
Authority: GB
Inventors: Laurence David Cook; Christopher Stephen Cook; James John Cook
Original assignee: SIL DIE SYSTEMS Ltd
Current assignee: SIL DIE SYSTEMS Ltd
Priority date: 2003-07-02
Filing date: 2003-07-02
Publication date: 2005-01-05
Also published as: GB0315416D0; WO2005002855A1

Abstract

An apparatus is described for mounting dies 22 on a bed 10 of a press. The apparatus comprises a support plate 14 for mounting in a predetermined position on the bed 10, a plurality of through holes 16' formed in the support plate 14', and clips 28 fitted in the holes 16' in the support plate 14 for securing the dies 22 to a front face 18 of the support plate. Each die securing clip 28 comprises a block (Fig 1, 30) which rests on the front face (Fig 1, 18) of the support plate 14' adjacent the associated die 22. A leg 38' protruding from the block 30 passes through one of the holes 16' in the support plate 14'. A flange 40 extending laterally from the leg 40 engages a rear surface 20 of the support plate 14'. A screw 34 received in a threaded bore (Fig 1, 32)in the block protrudes laterally from the block (Fig 1, 30) to grip a side edge (Fig 1, 24) of the associated die 22. A locking screw (Fig 1, 26) is used to prevent unintentional loosening of grub screw 34. The flange 40' prevents the block (Fig 1, 30) from lifting off the support plate 14'.

Description

240345 1 - 1 Apparatus for Positioning Dies on the Bed of a Press

Field of the invention

The present invention relates to apparatus for positioning dies on the bed of a press, for use for example in hot foil blocking and embossing.

Backaround of the invention

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There are several applications where a sheet is pressed against a die in order to make an impression on the sheet.

In hot foil blocking, for example, a foil is pressed by means of a heated die to apply a coating made of, or resembling, a metal foil to selected regions of a carrier sheet. In embossing, a carrier sheet is compressed between complementary male and female dies to achieve the desired raising of selected regions of the sheet from its plane.

Most presses used in such applications comprise two horizontal beds, also referred to as chases, on which dies are mounted. Where the beds are horizontal, the upper one is commonly pneumatically operated and carries the dies. In operation, the beds are separated by raising the upper bed 2s and/or lowering the lower bed, a carrier sheet is introduced between the two beds, the beds are brought together to make the desired impression on the carrier sheet and finally the carrier sheet on which an impression has been made is removed and replaced by the next carrier sheet.

Such presses are required to operate at high speed and in order to reduce the time taken to complete a given run, it is usual to make numerous impressions on different areas of a carrier sheet all at the same time. For example, if an area of gold lettering is to be applied to a small cardboard package, then the blanks for several such packages may be formed on a single large carrier sheet of cardboard which is - 2 cut into individual blanks after the printing and foil blocking operations have been completed.

In such an application, it is not viable for several reasons to produce a single die to make the multiple impressions. The primary reason for this is that the spacing between impressions may need to be adjusted to compensate for thermal expansion of the dies as well as for stretching or shrinking in the sheets on which impressions lo are made. Aside from these factors, it would be necessary for the entire die to be replaced if any part of it were to be damaged. For these reasons, several separate dies are produced and they are all individually mounted on the bed(s) of the press.

To this end, it is known to form at least one of the beds of the press as a thick plate of steel having a regular matrix of anchoring holes. Expanding pegs, referred to in the art as dogs, which grip within these holes, are used to anchor the individual dies to the bed. In other presses, the beds do not have a matrix of holes and the dies are screwed directly into the beds. The dies are themselves made of a metal plate (typically copper, steel, brass, magnesium or zinc) onto which the desired pattern has been formed by a photographic etching process that is well known in itself and need not be described within the context of the present invention.

Conventionally, all the individual dies are positioned on the beds using dogs and a test is run to ensure that their position is in register with the existing markings on the cardboard carrier sheets. Adjustments are made to the individual dies and the test procedure is repeated until all the dies are in their correct position. This setting up procedure of the dies may take several hours. At the end of a run, the dies are removed to allow the same press to be used for another job and should a fresh run later be - 3 - required, the setting up procedure of the dies must be repeated and during this time no other Use may he made Of the press.

To avoid wasting time in repeating the procedure of setting up the dies for each run and to reduce the down time of the press, it has previously been proposed, for example in GB 2372963 and GB2346589, to place a thin support plate between the dies and the bed and to secure the dies to the lo support plate so that they can be removed from the bed and replaced while remaining in their correct relative position.

To avoid modification to the beds of the press, it is necessary for the combined thickness of the dies and the support plate to be equal to the thickness of a conventional die, this being typically about 6 mm. This places a limitation on the thickness of the support plate, which is normally around 2 m. With so little metal to grip, it has proved difficult to secure the dies to the support plate.

To avoid this problem, GB 2372963 proposes attaching to the support plate threaded inserts that protrude from the rear of the support plate (the front being the face to which the dies are secured) into holes formed in the bed. However, the threaded inserts need to be pre-fitted to the support plate before the latter is placed on the bed, because the holes into which they fit have to be countersunk and the heads of the inserts have to be ground flat.

Summary of the invention

With a view to simplifying the manner in which the dies are secured to the support plate, the present invention provides apparatus for mounting dies on a bed of a press, comprising À a support plate for mounting in a predetermined position on the bed, À a plurality of holes formed in the support plate, and À clips fitted in the holes in the support plate for securing the dies to a front face of the support plate, wherein each die securing clip comprises À a block to rest on the front face of the support plate adjacent the associated die, À a leg protruding from the block, passing through one of the holes and having a flange engaging a rearward facing surface defined by the support plate, and a lo À clamping mechanism on the block for contacting a side edge of the associated die to prevent movement of the die relative to the support plate and prevent the clip from being withdrawn from the hole in the support plate.

Preferred features of the invention In a first embodiment of the invention, the holes in the support plate have a constant cross section and the leg of the die securing clip protrudes beyond the rear face of the support, the lateral flange engaging the rear face of the block. With such an embodiment, it is necessary for the bed of the press to have holes to receive the protruding; ends of the clips and it i, common for presses to have beds constructed with such a matrix or honeycomb of holes. If the holes in the support plate are smaller than the holes in the bed, then the flange of the leg of the clips can engage the rim of the hole and still be accommodated within the hole in the bed.

In order to enable the apparatus to be used with any form of bed, that is to say with or without holes, it is preferable for the holes in the support plate to have stepped or tapering sides and for the lateral flange of the leg of the die securing clip to engage the side of a hole, so that the leg does not protrude beyond the rear face of the support plate. - 5

In the preferred embodiment of the invention, the clamping means comprises a screw received in a threaded bore in the block.

Conveniently, the screw protruded laterally from the block in the opposite direction to the flange of the leg.

It is preferred for the threaded bore in the block of the die securing clip to be inclined at an angle of between lo 0 and 5 to the face of the block in contact with the support plate. By slightly inclining the screw and slightly tapering the sides of the dies, it is possible ensure that the screws push the dies towards the front face of the support plate to maintain good thermal conduct and avoid their being moved accidentally.

The screw holding down the die is conveniently a grub screw of which only one end protrudes from the block. A locking screw may then be mounted in the threaded bore and tightened on to the end of the grub screw to prevent it loosening unintentionally.

It is an advantage of the apparatus of the invention that it may be used not only with presses having flat beds but with those having counterrotating cylindrical bed. For such a press, the support plate may be curved to wrap around the bed of the press but the same principle of operation of the die retaining clips may be applied though the various faces of the clips may now need to be cylindrical.

Brief description of the drawings

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partial section through a first apparatus embodying the invention, - 6 - Figures 2 and 3 are similar partial section of two further embodiments of the invention, Figure 4 shows a modification of the embodiment of Figure 3 in which a spring steel plate is introduced between the block of the mounting clip and the support plate, and Figure 5 is a perspective view of the spring steel plate of E7igure 4.

Detailed description of the preferred embodiments

Figure 1 shows a bed or chase 10 of a hot foil blocking press. Dies 22 are fitted to the upper surface of the bed as viewed but this is upside down in relation to the orientation of the bed when the press is in use.

The bed 10 shown in Figure 1 has holes 12 that are conventionally used to receive dogs for locating the dies 22 in their desired position. As earlier mentioned, mounting dies in this manner would prolong the setting up time at the commencement of each run.

Instead, a support plate 14 is placed over the bed 10 and is used to support the dies 22 in their correct relative position when they are in storage between runs. The combined thickness of the plate 14 and the die 22 in Figure 1 is about 6 mm, this being the thickness of a conventional die that is intended to be mounted directly on the bed 10. Typically, the support plate has a thickness of around 2 mm and the die a thickness of 4 mm.

The support plate 14 has a front face 18 on which the dies 22 are placed and a rear face 20 that contacts the surface of the bed 10. Additionally, the support plate is formed with holes 16 that align with the holes 12 in the bed but have a smaller diameter than the holes 12 in the bed 10. - 7

The dies 22 has raised regions 26 that are used in forming the desired impression or. the carrier sheet. The edge regions 24 of the dies 22 are tapered at a slight angle to help in clamping them down onto the surface 18 of the support sheet 14. The clamping of the dies is effected by means of clips that are generally designated 28. Each clip comprises a small block 30 that is less thick than the dies so as not to leave any impression on the carrier sheet during the pressing operation. The block 30 is formed with lo a threaded bore 32 that is generally parallel to the surface 18 being inclined relative to it at an angle of between 0 and 5 . A grub screw 34 engaged in the threaded bore protrudes from the block 30 into contact with the edge 24 of the die and a locking screw 26 is used to prevent unintentional loosening of the grub screw 34.

When two or more such clips 28 are placed around a die 22, it is firmly held in place and prevented from moving from side to side. Furthermore, the inclination of the edge 24 and the screw 34 create a component of force that urges the die 22 tightly against the surface 18 of the support plate.

Each clip 28 is held in place on the support plate 14 by means Of a leg 38 depending from the block 30 which passes through one of the holes 16 in the support plate 14.

The leg 38 protrudes beyond the rear surface 20 of the plate 14 into one of the holes 12 in the bed 10. The leg 38 is rendered L- shaped by a small flange 40 that extends from the leg 38 in the opposite direction from the protruding screw 34 and engages behind the rear face 20 of the support plate 14. The leg 38 thus hooks over the edge of the hole 16 and prevents the block from lifting off the support plate 14.

Because the screw 34 and the flange 40 extend in opposite directions, the single action of tightening the screw 34 acts to clamp both the clip 28 and the die 22 to the support plate 14.

In_ plate 14 reeds itself to be separately anchored to the bed 10 and to this end it is also formed with larger holes, such as the hole 42 for receiving a known bolt and lock clip. Of course, any other suitable technique may be used to hold the support,olate 14 in a predetermined position on the bed 10.

A disadvantage of the clips used in the first lo embodiment of the invention is that they need to protrude beyond the rear face 20 of the support plate 14. For this reason, this embodiment can only be used when the bed has holes 12 that line up with the holes 16. When there are no conveniently located holes 12 in the bed to receive the protruding legs 38, the support plate 14 cannot lie flat against the bed 10.

To overcome this disadvantage the embodiments of Figures 2 and 3 have legs that do not protrude from the rear face of the support plate. In describing these two embodiments, the same reference numerals will be used to designate like components but a prime will be added to the reference numerals of components that have been modified.

In the embodiment of Figure 2, the support plate 14' is modified by countersinking the holes 16' from the rear of the support plate 14'. The leg 38' is shortened as compared with the leg 38 so as not to protrude beyond the rear face of the support plate 14'. Lastly, the flange 40' instead of being defined by an L-shaped leg is formed by an undercut in the side of the leg 38'.

The operation of the clip is essentially the same as previously described, the main difference being that the clip now engages the countersunk side of the hole 16' instead of engaging behind the rear face of the support plate. It is thanks to this modification that the leg 38' 9 can be shortened, avoiding the requirement for aligned holes 12 in the bed 10. Nevertheless, the holes if present do not interfere with the operation of the clips making the die supporting apparatus universally applicable.

The embodiment of Figure 3 is similar in principle to that of Figure 2 but the sides of the holes 16" are stepped by counter-boring from the rear instead of being countersunk. The leg 38" can this time once again be L o shaped with the flange 40" engaging the shoulder in the side of the hole 16" but the size of the leg is once again reduced to fit within the thickness of the support plate 42".

The screw 34 in each of the above described embodiments is harder than the material of the dies 22 and there is a tendency for it to indent the die 22 when it is tightened.

The presence on an indentation makes it difficult to make a small adjustment to the position of the die because the screw 34 will tend always to centre itself in the existing indentation. To avoid this problem, it is possible, as shown in Figure 4, to sandwich a spring steel plate 48 between the block 28 and the support plate 14. As shown in Figure 5, the spring steel plate 48 has an elongate slot 52 to receive the protruding leg 38 of the block and an inclined strip 50 at one end to rest between the screw 34 and the die 22. The strip 50 prevents the screw 34 from indenting the die but its flexibility allows the die 22 to be held down firmly.

Though illustrated as a modification of the embodiment of Figure 3, the spring steel plate 48 can of course be used in any of the previously described embodiments.

It is an advantage of all the embodiments of the invention that the clips 28 and the dies 22 can be positioned as necessary before or after the support plate 14 has been mounted on the bed of the press. After the dies have been placed in their desired positions, clips 28 are pushed into nearby holes 16 in the support plate '4 and the screws 34 are tightened to clamp the dies in position. The size of the clips 28 and the separation of the holes 16 are chosen so that there are always holes sufficiently near the edge of any die to be within the adjustment range of the screw 34. As the sides of dies are normally square (parallel to the sides of the bed), it helps in this respect if the holes 16 are arranged in the support plate so that lo their centres lie on a line inclined to the sides of the bed.

Though described by reference to a press having flat beds, it will be clear to the person skilled in the art that the invention can equally be applied to presses have counter-rotating cylindrical beds. In this case, the support plate 14 may be constructed of separate arcuate shoes that are secured to the surface of the drum-like bed Or of a single hollow sleeve that is slipped over the cylindrical bed from one end and tightened to grip it firmly. The only difference in the dies and the clips will be that the previously flat surfaces will need to be! cylindrically curved to match the curvature of the bed but in an axial section such embodiments would look no different from the embodiments of Fiqures 1 to 3.

It will be appreciated that various modification may be made to embodiments described without departing from the scope of the invention as set out in the appended claims.

For example, the clamping means need not simply be a screw may comprise a cam plate mounted on the block to engage the side of the die. If a screw is used as a clamping means in need not lie generally parallel to the surface of the support plate but at right angles to it. In this case, the screw may bear down on a foot that projects laterally from the edge of the die.

Various configurations can furthermore be adopted to enable the leg to engage a rearward facing surface c.efined by the holes. For example, each hole may comprise a narrow slot that is stamped in the support plate and that is widened on the reverse side into a circular hole. The hole has the same diameter as the length of the slot but is only half as deep as the thickness of the support sheet. The leg may now be formed as a screw head with flats on its opposite sides so that it can be passed through the narrow slot and lo then rotated through 90 to engage within the circular hole machined in the rear face of the support sheet.

Claims

Apparatus for mounting dies on a bed of a press, comprising À a support plate fo' mounting in a predetermined position on the bed, À a plurality of holes formed in the support plate, and À clips fitted in the holes in the support plate for securing the dies to a front face of the support plate, To wherein each die securing clip comprises À a block to rest on the front face of the support plate adjacent the associated die, À a leg protruding from the block, passing through one of the holes and having a flange engaging a rearward facing surface defined by the support plate, and a À clamping mechanism on the block for contacting a side edge of the associated die to prevent movement of the die relative to the support plate and prevent the clip from being withdrawn from the hole in the support plate.
2. Apparatus as claimed in claim 1, wherein the clamping means comprises a screw received in a threaded bore! in the block.
3. Apparatus as claimed in claim 2, wherein the screw protrudes laterally from the block in the opposite direction to the flange of the leg.
4. Apparatus as claimed in claim 3, wherein the threaded bore in the block of the die securing clip is inclined at an angle of between 0 and 5 to the face of the block in contact with the support plate.
5. Apparatus as claimed in claim 2 or any claim appended thereto, wherein the screw is a grub screw of which only one end protrudes from the block.
6. Apparatus as claimed in claim 5, wherein a locking screw is mounted in the threacied bore to be tightened on to the end of the grub screw.
7. Apparatus as claimed in any of claims 2 to 6, wherein the cla.nping means further Includes a spring steel plate slidably mounted between the block and the support plate and incorporating an inclined strip located between the end of the screw and the side edge of the die.
8. Apparatus as claimed in any preceding claim, wherein the holes in the support plate have a constant cross section and the leg of the die securing clip protrudes beyond the rear face of the support, the lateral flange engaging the rear face of the support plate.
9. Apparatus as claimed in any of claim 8 in combination with a press having a bed on which the support plate is mounted, wherein the bed is formed with holes and wherein the holes in the support plate are positioned to overlie holes in the bed with the edges of the holes in the support plate misaligned with the edges of the holes in the! bed.
10. Apparatus as claimed in any of claims 1 to 7, wherein the holes in the support plate have stepped or tapering sides and wherein the lateral flange of the leg of the die securing clip engages the side of a hole and the leg does not protrude beyond the rear face of the support plate.
11. Apparatus as claimed in claim 10 in combination with a press having a bed on which the support plate is mounted, wherein the bed of the press is not formed with holes.
12. Apparatus as claimed in any preceding claim, for mounting in a press having a rotating cylindrical bed - 14 wherein the support plate is curved to wrap around the bed of the press.
13. Apparatus for mounting dies on a bed of a press, constructed substantially as herein before described with reference to and as illustrated in Figure 1, 2, 3 or 4 of the accompanying drawings.