GB2200315A

GB2200315A - Cutting and creasing forme for blanks

Info

Publication number: GB2200315A
Application number: GB08701625A
Authority: GB
Inventors: Geoffrey Maurice Morris
Original assignee: RALEGH CUTTING FORMES Ltd
Current assignee: RALEGH CUTTING FORMES Ltd
Priority date: 1987-01-26
Filing date: 1987-01-26
Publication date: 1988-08-03
Anticipated expiration: 2007-01-26
Also published as: GB8701625D0; GB2200315B

Abstract

The forme comprises a main die 2 with cutting blades 3 and creasing rules 4 and a counter die 5 with creasing grooves (6, Fig. 2) which correspond with respective creasing rules 4 of the main die 2, wherein the main die 2 is provided with holes 9 for receiving therein respective locating pins (35, Fig. 4) for locating the two dies 2, 5 in registration with each other, the holes being defined by at least three, and preferably six, planar surfaces extending into the main die 2. Steel locating pins (35) are preferably used and, in accordance with a further aspect of the invention, the periphery of the counter die (31, Fig. 3) extends to at least the periphery of a blank which is to be cut and creased by the forme, the blank periphery being defined by the cutting blades 3 of the main die 2. For setting the counter die up on the main die, a shoulder in the holes 9 locates the pins (35 at the right height and a press plate 40, Fig. 4) is brought into contact with a contact adhesive layer on the counter die and simultaneously urges the pins into a smaller cross-sectioned portion (911) of the holes below the shoulder, compressing rubber ejector blocks (11) so that the pins are driven so far into the holes to prevent their interfering with the cutting and creasing operations. <IMAGE>

Description

CUTTING AND CREASING FORME FOR BLANKS DESCRIPTION This invention relates to a cutting and creasing forme for blanks and is especially, but not exclusively, related to such a forme for cutting and creasing one-piece blanks of solid fibreboard or corrugated board, which blanks can be erected subsequently into cartons, boxes or like forms of container.

Known cutting and creasing formes generally comprise a die with cutting blades for cutting blanks to the correct size and shape from pieces of board, and with creasing rules for providing, simultaneously, creases in the cut blanks, the cutting blades and creasing rules protruding above the working surface of the die by respective predetermined amounts. These types of known forme also include a separate counter die with creasing grooves which correspond with the creasing rules of the first-mentioned die.In use of the formes, the die and counter die are secured to respective press plates, such that, when the press plates are brought together, with a piece of board located therebetween, the periphery of the counter die lies within the periphery of the blank defined by the outermost cutting blades of the die, such that the cutting blades just engage the working surface of the press plate to which the counter die is secured, with the creasing grooves of the counter die lying in register with the corresponding creasing rules of the die.

Thus, the counter die has to be shaped and dimensioned very accurately, which is an expensive procedure. Further the peripheral edge of the counter die is bevelled or chamfered, which adds to the cost of its manufacture.

When the press is set up, the die and counter die have to be positioned accurately, with respect to each other, on their respective press plates and this is achieved by placing the two dies in confronting relationship with each other and using locating pins which extend through in register holes in the dies, to maintain this registration exactly. The die with the cutting blades and creasing rules is usually secured initially to its press plate before this registration procedure is carried out. Subsequently, the other press plate is brought into contact with the surface of the counter die remote from the other die, which surface is generally provided with a contact adhesive for securing the counter die to its press plate in exact register with the other die.

In these known types of forme, the registration and locating holes for the locating pins, which are circular in cross-section, are also circularly cross-sectioned, the pins being made of either a plastics material or aluminium, thereby having a short working life, in that they are readily damaged when removed from the die after the setting-up procedure. Also, the locating pins have to be removed from the die with the cutting blades and creasing rules before any blanks can be cut and creased; otherwise, the pins produce undesirable marks upon the blanks, thereby causing damage to any printing on the blanks, when the associated press plates are brought together during the cutting and creasing operations.

In another type of known forme,. the counter die is replaced completely by so-called 'self-locating, creasing matrix' which, in effect, avoids the need for a counter die as such by replacing the counter die creasing grooves with suitably shaped and dimensioned channelling. This channelling is initially attached to the creasing rules of the die, such that, when the press plates are brought together for the first time, the channelling is secured by an adhesive backing to its press plate, thereby ensuring its correct registration with the creasing rules during blank manufacture.

When the press plates are separated initIally, the channelling is removed from its corresponding creasing rules on the die.

However, the use of this type of crease channelling is labour intensive, in that it has to be very carefully cut to size, such that it corresponds precisely with the corresponding creasing rules.

The objects of the various aspects of the presently inventive cutting and creasing forme are to eliminate, or at least substantially reduce, the disadvantages associated with the known types of forme discussed above.

Accordingly, one aspect of the present invention provides a cutting and creasing forme for blanks, comprising a main die with cutting blades and creasing rules, the cutting blades defining the periphery of a blank to be cut and creased by the forme and the creasing rules being located within said periphery, and a counter die with creasing grooves which correspond with respective creasing rules of the main die, wherein the periphery of the counter die extends to at least the blank periphery defined by the cutting blades of the main die.

In a preferred embodiment of the inventive forme, the periphery of the counter die extends beyond the periphery of the blank defined by the cutting blades of the main die, in which case, the latter, namely, the main die cutting blades, can be arranged not to engage the working surface of the press plate to which the counter die is secured. This is contrary to the prior art arrangement discussed above, wherein the main die cutting blades always engage the counter die press plate. This inventive arrangement also eliminates the need to cut the counter die exactly to size and shape to fit within the blank periphery defined by the main die cutting blades, as in the prior art discussed above. Further, there is no need to bevel or chamfer the peripheral edge of the counter die, because the counter die periphery will usually be rectangular and will lie outside the periphery of the blank.

In accordance with another aspect of the present invention, there is provided a cutting and creasing forme for blanks, comprising a main die with cutting blades and creasing rules and a counter die with creasing grooves which correspond with respective creasing rules of the main die, wherein the main die is provided with holes for receiving therein respective locating pins for locating the two dies in registration with each other, said holes being defined by at least three, and preferably six, planar surfaces extending into the main die.

Preferably, each of the locating holes comprises a first portion, which is defined by said at least three planar surfaces, and a second portion with cross-sectional dimensions which are less than those of the first portion, thereby defining a shoulder at the juncture of the first and second hole portions.

With this arrangement, the shoulder can be provided at the exact depth to receive a locating pin thereon, which pin is at precisely the correct height above the working surface of the main die for initial settingup of the forme with associated press plates.

The provision of these non-circular locating pin holes in the main die can be effected particularly well using a laser which is very accurate in its shaping and dimensioning capabilities. As indicated above, the preferred cross-section for the locating pin holes is hexagonal, although other suitable cross-sections may be used.

A further aspect of the present invention provides a steel locating pin for use with the formes discussed above and, particularly, that including the main die with the non-circularly cross-sectioned locating pin hole. Inventive steel locating pins have certain advantages over the plastics or aluminium locating pins, in that they are less readily damaged and can be re-used many times.

Preferably, at least one end of the steel locating pin is bevelled or chamfered, to facilitate its insertion into a locating hole. The cross-section of the inventive locating pin may be any which. is suitable, although a circular cross-section is preferred.

In order that the various aspects of the inventive forme can be more fully understood, embodiments in accordance therewith will now be described, with reference to a prior art arrangement, by way of example and with reference to the accompanying drawings in which: Fig. 1 is a plan view of a prior art forme including a cutting and creasing die, with a complementary creasing counter die shown superimposed thereon; Fig. 2 is a plan view of the counter die shown in Fig. 1; Fig. 3 is a plan view of a counter die of a forme in accordance with the present invention; and Fig. 4 is a a cross section, on an enlarged scale, of a part of the inventive forme of Fig. 3 being set-up with an associated blank forming press.

Referring firstly to Figs. 1 and 2 of the drawings, a prior art forme for cutting and creasing blanks has a main die, designated generally at 2, comprising a rectangular, planar 10-ply wooden support 2 with cutting blades 3, represented by the solid lines in Fig. 1, which are located in slots (not shown) cut in the support 2 by laser and which protrude a predetermined height above the working surface of the support. These cutting blades 3 define the periphery of the blanks (not shown) to be cut and creased by the forme 1.

Creasing rules 4, represented by the double lines in Fig. 1, are located in further slots (also not shown) cut by laser in the support 2 and protrude above the working surface thereof to another predetermined height just lower than that of the cutting blades 3.

Superimposed upon the main die 1 is the peripheral outline of a prior art counter die 5, shown in dashed lines, which is the counter die 5 shown in Fig. 2 but laterally inverted with the working surfaces of the two dies 1,5 confronting each other.

The counter die 5 has creasing grooves 6 inscribed in its working surface, which, in Fig. 1, lie in register with the corresponding creasing rules 4, the periphery of the counter die 5 lying within the confines of the periphery of a blank defined by the cutting blades 3. The peripheral edge of the working surface of the counter die 5 is bevelled or chamfered at 7, with the bevel or chamfer facing the working surface of the main die 1.

The counter die 5 is also provided with eight circular locating holes 8 which, in Fig. 1, lie in register with respective, laser formed through holes 9 in the main die support 2. In accordance with a preferred embodiment of an aspect of the invention, these holes 9 are hexagonal in cross-section and, as shown in Fig. 4, have first and second portions 9' and 9'', the latter 9'' having a smaller crosssectional dimension than that of the former 9', thereby defining a shoulder 10 at the juncture thereof.

As shown in Fig. 4 also, the cutting blades 3 each has a series of rubber ejector blocks 11 which are secured to the working surface of the support 2 by adhesive and which extend along opposed sides of the blades 3, generally parallel thereto and spaced therefrom. However, these ejector blocks 11 have been omitted from Fig. 1 for reasons of clarity.

The purpose of these ejector blocks 11 is to eject a cut and creased blank from the cutting blades 3, after the blocks 11 have been compressed by the press plates and the latter have parted. Otherwise, each blank would be retained on the main die blades 3, due to the strict cutting tolerances involved.

Referring now to Fig. 3, here is shown a counter die of a forme in accordance with another aspect of the invention. This counter die 31 is made from the same material as that of the counter die 5 described above in relation to the prior art forme shown in Figs 1 and 2, this material being laminated glass fabric sheet sold under the Trade Mark VETRONIT.

The counter die 31 is rectangular and has inscribed in its working surface creasing grooves 32 which are identical to those of the counter die 5 described above, as are the locating pin holes 33 and the holes 8 in the counter die 5.

When the counter die 31 is laterally inverted and superimposed upon the main die support 2 of Fig.1, its periphery 34 extends beyond that of a blank defined by the cutting blades 3, such that the latter will not engage the surface of a press plate to which the counter die 31 is secured, as they do in the prior art arrangement described above in relation to Figs.

1 and 2, wherein the counter die periphery lies within the confines of the cutting blade-defined blank periphery.

In order to set-up a blank cutting and creasing press using a forme in accordance with the present invention, a main die, such as that shown in Fig.

1, is prepared with the cutting blades 3 and creasing rules 4 mounted in respective slots in the support 2 and protruding by the predetermined height above the working surface thereof.

Because the cutting blades 3 do not engage the working surface of the press plate to which the counter die is secured, they are set to protrude a little lower from the working surface of the main die support 2 than those of the main die of the prior art forme 1.

As shown in Fig. 4, a counter die 31. of the inventive forme is positioned upon the rubber ejector blocks 11 secured to the working surface of the main die support 2, with the creasing grooves 32 inscribed in its working surface facing the creasing rules 4 in register therewith. The steel locating pins 35 (only two shown) are inserted through the in register locating holes 33 in the counter die 31 and the hexagonally cross-sectioned locating holes in the main die support 2, such that the lower end of each pin 35 engages upon the shoulder 10 defined at the juncture of the first and second portions 9' and 9'' of these holes. Thus, the pins 35 are located at exactly the correct height with respect to the positioned counter die 31, whilst maintaining the two dies 2 and 31 in the proper registration with respect to each other.

A backing paper (not shown) is peeled off the surface of the counter die 31 remote from its working surface, to expose a layer of contact adhesive on that remote surface.

Then, the press plate 40, to which the counter die 31 is to be secured, is brought into contact with the adhesive layered surface of the die 31, whilst simultaneously urging the steel locating pins down into the second, smaller cross-sectioned portion 9'' of the respective locating holes 9 in the support 2.

At this stage it is to be appreciated that the support 2 is also secured to its own press plate (not shown) and that the ejector blocks 11 will be compressed by the action of the press- plate 40 upon the counter die 31, to cause the locating pins 35 to be urged downwardly into a position within the holes 9 which does not interfere with the subsequent cutting and creasing of the blanks.

Now, the press is set-up, with the two dies in exact register with each other and the periphery 34 of the counter die 31 beyond and surrounding the periphery of the blank which is defined by the outermost cutting blades 3 of the main die.

In the blank cutting and creasing operation, a sheet of board is located in the required position upon either the main die, resting upon the blocks 11, or upon the counter die 31, depending on the particular operation of the press, and the press plates are then brought together. The blocks 11 are compressed by this action and the cutting blades 3 of the main die cut through the board, such that they just engage the working surface of the counter die 31, without cutting therethrough. Simultaneously, the creasing rules 4 of the main die and the creasing grooves 32 of the counter die cooperate with each other, with the board located therebetween, to form the . creases in the cut blank. Then, the press plates are separated and the compressed blocks 11 return to their original shape, thereby ejecting both the blank and waste board from the cutting blades 3.This operation is repeated upon consecutive sheets of board.

Thus, it can be seen that the various aspects of the present invention provide a number of advantages over the prior art, for example: 1. Because the periphery of the counter diefdoes not have to be cut to an exact shape to lie within the confines of the blank periphery-defining cutting blades, less time and cost is involved in the making of the counter die; 2. The peripheral edge of the counter die does not have to be chamfered to prevent "bruising" of the edges of the cut blank due to the compressive action of the ejector blocks during cutting and creasing, because this problem is not encountered due to the fact that the periphery of the counter die lie outside that of the blank; 3. The cutting blades no longer engage the press plate to which the counter die is secured, thus increasing the working life of the blades; 4.The locating holes in the main die support for the locating pins provide a means whereby the pins are retained therein after setting-up of the press, instead of having to remove the pins, as in the case of the prior art arrangements; and 5. The steel locating pins have a longer working life than the prior art plastics or aluminium locating pins.

Further, it is to be appreciated that the inventive concept also embraces a number of other general aspects, for instance, a method of cutting and creasing a blank using a forme including a main die with cutting blades and creasing rules, the or the outermost cutting blades defining the periphery of a blank cut and creased by the forme and the creasing rules being located within said periphery, and a counter die with creasing grooves which correspond with respective ones of the creasing rules of the main die, wherein, as the two dies are brought together in registration with each other and with a piece of board, from which the blank is to be cut, located therebetween, the periphery of the blank defined by said cutting blades lies within the periphery of the counter die.

As discussed above, the cutting depth of the cutting blades is preferably such that, during the cutting and creasing of the blank, the blades do not engage a press plate to which the counter die is secured and, instead, engage the confronting surface of the counter die.

Additionally, the invention also provides a method of setting-up a press for cutting and creasing a blank using a main die secured to one press plate and having cutting blades and creasing rules and a counter die with creasing grooves corresponding to respective creasing rules of the main die, wherein the counter die is placed in registration with the main die and is maintained in said registration by means of locating pins which are passed through respective holes in the counter die lying in register with corresponding holes in the main die and which are received in respective ones of the main die holes and wherein the main die holes are defined by at least three, and preferably six, generally planar surfaces extending into the main die.

Advantageously, the main die holes each comprise a first portion, which is defined by said at least three planar surfaces, and a second portion with cross-sectional dimensioned which are less than those of the first portion, thereby defining a shoulder at the juncture of the first and second hole portions, such that the end of the respective locating pin received in the hole engages said shoulder.

Subsequently, the counter die is secured to the other press plate, whilst maintained in such registration with the main die and as the two press plates are brought together.

As discussed above, the depth of the shoulder in the main die and the length of the locating pins are such that, as the press plates are brought together during the initial setting-up procedure, the locating pins are urged into the second, lesser dimensioned portions of the respective holes and are maintained there during the subsequent blank cutting and creasing operations.

A further point concerning the locating pins is that when the in register locating holes in the main and counter dies lie within the periphery of the blank defined by the cutting blades, the pins should be urged further into their respective holes in the main die after the setting-up of the press has been completed, so that the exposed ends of the pins do not mark or damage the blanks when being cut and creased. This can be achieved by giving the pins a sharp tap, such that they are urged further into the second, smaller dimensioned portions of the locating holes.

However, the 'inventive forme provides an alternative to the above arrangement for the locating holes, in that, because the periphery of the counter die lies outside that of the blank defined by the cutting blades of the main die, thus providing excess board between those two peripheries, the holes can, in certain circumstances, be located, in both the main and counter dies, outside the periphery of the blank. In this case, there is no need to urge the locating pins further into their respective holes once the settingup procedure has been completed, because any damage which they may cause to the board from which the blank is cut, will lie in the excess or waste board outside the periphery of the blank, thus causing no damage to the blank itself.

Claims

1. A cutting and creasing forme for blanks, comprising a main die with cutting blades and creasing rules and a counter die with creasing grooves which correspond with respective creasing rules of the main die, wherein the main die is provided with holes for receiving therein respective locating pins for locating the two dies in registration with each other, said holes being defined by at least three planar surfaces extending into the main die.

2. A forme according to claim 1, wherein each of the locating holes comprises a first portion, which is defined by said at least three planar surfaces, and a second portion with cross-sectional dimensions which are less than those of the first portion, thereby defining a shoulder at the juncture of the first and second hole portions, with the shoulder being provided at substantially the exact depth for receiving a locating pin thereon, so that the pin is at the correct height above the working surface of the main die for initial setting-up of the forme with associated press plates.

3. A forme according to claim 1 or 2, wherein each hole is defined by six of said planar surfaces, such that the cross-section of each hole is hexagonal.

4. A forme according to claim 1, 2 or 3, wherein the locating holes in the main die have been formed using a laser.

5. A forme according to any of claims 1 to 4, wherein the cutting b-lades of the main die define the periphery of a blank to be cut and creased by the forme, with the periphery of the counter die extending to at least said blank periphery.

6. A steel locating pin for use with a cutting and creasing forme for blanks.

7. A steel locating pin for use with a cutting and creasing forme according to any of claims 1 to 5.

8. A steel locating pin according to claim 6 or 7, wherein at least one end fo the pin is bevelled or chamfered, to facilitate its insertion into a locating hole.

9. A steel locating pin according to claim 6, 7 or 8 with a circular cross-section.

10. A cutting and creasing forme for blanks, comprising a main die with cutting blades and creasing rules, the cutting blades defining the periphery of a blank to be cut and creased by the forme and the creasing rules being located within said periphery, and a counter die with creasing grooves which correspond with respective creasing rules of the main die, wherein the periphery of the counter die extends to at least the blank periphery defined by the cutting blades of the main die.

11. A forme according to claim 10, wherein the periphery of the counter die extends beyond the periphery of the blank defined by the cutting blades of the main die, whereby the main die cutting blades can be arranged not to engage the working surface of an associated press plate to which the counter die is secured during use of the forme.

12. A forme according to claim 10 or 11, wherein the main die is provided with holes for receiving therein respective locating pins for locating the two dies in registration with each other, said holes being defined by at least three planar surfaces extending into the main die.

13. A cutting and creasing forme for blanks substantially as hereinbefore described with reference to the accompanying drawings.

14. A steel locating pin for use with a cutting and creasing forme for blanks, substantially as hereinbefore described with reference to the accompanying drawings.

15. A blank when cut and creased by means of a forme according to any of claims 1 to 5 and 10 to 13.