GB2180504A

GB2180504A - Creasing machines

Info

Publication number: GB2180504A
Application number: GB08523191A
Authority: GB
Inventors: Michel Said Achou
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-09-19
Filing date: 1985-09-19
Publication date: 1987-04-01
Also published as: GB2180504B; GB8523191D0

Abstract

A die 12 of a creasing machine comprises a bed plate 13 of hardened steel, having a completely flat upper surface 17. Channels 14 for creasing knives 15 are afforded by rules 19, which are formed of hardened steel, and are secured to the hardened steel plate 13 by means of a layer 20 of a cured adhesive such as epoxy resin, so as to be substantially immovable. To position the rules 19 on the bed plate 13, the rules 19 may be carried on the creasing knives 15 by means of holding strips 21, coated with adhesive, and then pressed down upon the bed plate 13. The strips 21 are subsequently discarded. <IMAGE>

Description

SPECIFICATION Creasing machines This invention relates to creasing machines, and is concerned particularly with dies therefor.

Die-cutting and creasing machines are used widely for various purposes, and very often for forming carton blanks. Typically, a cutting and creasing machine will comprise a matrix of cutting and creasing knives, which are arranged to co-operate with a bed plate which is provided with a matrix of creasing channels.

A blank of material is disposed between the knives and the bed plate, and in a subsequent stamping operation, the cutting knives cut out the blank to the required size, whilst the creasing knives engage their corresponding channels, with the blank material therebetween, to form the desired creases.

A problem that arises with such cutting and creasing machines is that of forming the bed plate and its channels at a reasonable cost. A traditional method of manufacturing such a plate is to engrave a steel plate with desired channels (either by etching or by machining).

However, in order to permit the engraving operation, it is necessary that the steel plate is not of hardened steel. Thus, where cutting knives co-operate directly with the plate, there is progressive wear, which will eventually reach an unacceptable level, at which time the plate will become useless. Moreover, it will be appreciated that the operation of engraving is itself very expensive. It will further be appreciated that a die manufactured in such a way has only scrap value when it is no longer desired to process blanks to the particular etched configuration.

A proposal has been made to provide cheaper dies for creasing machines, by affixing to a steel plate a matrix of rules of a plastics material, which rules are provided with a selfadhesive strip. Such rules may readily be affixed to the plate in desired positions, and provide the channels with which the creasing knives cooperate. Moreover, they may readily be removed and replaced on the plate, for forming blanks of differing configurations.

However, this cheaper alternative does suffer a number of disadvantages. Firstly, the rules themselves tend to be subject to considerable wear, and although they are readily replaceable, this does lead to an unacceptable down time in an associated machine. Moreover, although of plastics material, the rules are rather expensive, and replacing the rules when worn can be a very costly exercise, not only in down time, but also in materials. A further disadvantage arises from the use of the self-adhesive backing. Although this permits easy positioning and re-positioning, it does tend to allow a degree of relative movement between the rules and the plate, which may become unacceptable, especially in warm conditions-e.g. under ambient temperatures in a hot country.Thus, it is very often necessary to stop an expensive creasing machine at frequent intervals, to reposition the rules.

Thus, although plates which are provided with plastics rules may have distinct advantages over the more traditional engraved plates, they are far from free of difficulties, and there still exists a need for a die for a creasing machine, which die is both relatively inexpensive to manufacture and capable of reformatting, whilst still affording a satisfactory degree of reliability and precision in operation.

Preferred embodiments of the present invention aim to provide dies for creasing machines, which may be improved in the foregoing respects.

According to a first aspect of the invention, there is provided a die for a creasing machine, the die comprising a plate and at least one rule which is secured to the plate and is formed with a channel which is adapted to receive a creasing knife such that, in use, a blank may be placed between the rule and the knife and creased by engaging the knife in the channel, both the plate and the rule being of hardened steel and the rule being secured to the plate by means of a cured adhesive which substantially prevents relative movement between the rule and the plate.

in a second aspect, the invention provides a method of manufacturing a die for a creasing machine, comprising the steps of coating at least one hardened steel rule with a curable adhesive which, when cured, is substantially solid, applying the adhesive-coated rule to a hardened steel plate, and allowing the adhesive to cure such that it then substantially prevents relative movement between the rule and the plate, the rule being adapted to receive a creasing knife such that, in use, a blank may be placed between the rule and the knife and creased by engaging the knife in the channel.

The rule may be firstly engaged on a respective creasing knife (eg with the intermediary of a resilient holding strip) and the knife subsequently urged towards the plate, thereby to press the adhesive-coated rule against the plate.

The method may include the step of applying heat to the adhesive to promote curing thereof. The heat may be applied to the adhesive via the knife and/or the plate. The knife or a holder therefor may incorporate a heating element, to apply heat to the adhesive via the knife. The adhesive may comprise an epoxy resin.

The rule may comprise one element of a matrix of rules, adapted to co-operate with a corresponding matrix of creasing knives.

The invention also extends to a creasing machine incorporating a die in accordance with the first aspect of the invention, or manufactured in accordance with a method ac cording to the second aspect of the invention.

Such a creasing machine may comprise at least one cutting knife which-is adapted to cooperate with the plate to cut a blank simultaneously with a creasing operation.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 is a sectional diagram illustrating operation of a traditional creasing machine; and Figure 2 is a sectional diagram illustrating operation of a creasing machine embodying the invention.

The creasing machine that is illustrated diagrammatically in Figure 1 comprises a die 2 which consists of a steel bed plate 3, which is engraved with a matrix of channels 4. A matrix of creasing knives 5 is arranged to cooperate with the engraved channels 4, and a matrix of cutting knives 6 is arranged to cooperate with the upper surface 7 of the plate 3.

In use, a web of material (e.g. a web of cardboard-not shown) is disposed over the die 2, and the matrices of knives 5 and 6 are urged downwardly (as seen) towards the die 2. Each creasing knife 5 engages its respective channel 4, with the respective material therebetween, to form creases as required.

The cutting knives 6 co-operate directly with the upper surface 7 of the plate 3, to cut the material as required.

As mentioned above, the steel plate 3 may not conveniently be of hardened steel, as this does not readily permit of etching or machining. Therefore, below each cutting knife 6, there progressively appears an area 8 of wear on the top surface 7 of the plate 3. Thus, as mentioned above, the plate 3 eventually becomes unuseable.

In Figure 2, however, a corresponding die 12 comprises a bed plate 13 of hardened steel, which has a completely flat upper surface 17. In Figure 2, the channels 14 for the creasing knives 15 are afforded in respective rules 19, which are formed of hardened steel, and are secured to the hardened steel plate 13 by means of a layer 20 of epoxy resin.

Cutting knives 16 cooperate directly with the upper surface 17 of the plate 13.

To manufacture the die 12, the matrix of rules 19 is firstly engaged upon the matrix of knives 15, when in a retracted position. To this end, each rule 19 is provided with a respective resilient holding strip 21, having a lower projection which engages in the channel 14, and an upper groove- which engages around the respective knife 15. In Figure 2, the parts 15, 19 and 21 are shown disen gaged, in the interests of clarity. Thereafter, the undersurfaces of the rules 19 are coated with an epoxy resin, which is then allowed to dry for a suitable period (e.g. two hours). The matrix of knives 15, with the rules 19 attached via the strips 21, is then pressed firmly onto the steel plate 13, to cause the rules 19 to adhere to the plate 13, by means of the epoxy resin 20.

At this stage, the knives 15 may be removed, the strips 21 discarded, and heat then applied to the rules 19, to cause the epoxy resin 20 to cure. The heat may be applied by, for example, a stream of hot air. Alternatively, the knives 15 and/or the steel plate 13 may be provided with means for causing the direct application of heat to the rules 19 or epoxy resin layer 20. By way of example, the knives 15, or parts associated therewith (such as holders), may be provided with electrical heat ing means, which may cause heating of the epoxy resin, via the rulers 19, with the knives 15 engaged therein.

Adhesives other than epoxy resin may be used. For example, there are now available adhesives which will cure at ambient tempera tures in about 30 minutes, and yet provide a solid, immovable band.

It will be appreciated that the die 12 illus trated in Figure 2 may have a number of ad vantages over the conventional die 2 of Figure 1. Firstly, the hardened steel rules 19 may be fixed very simply and cheaply to the hardened steel plate 13. However, the rules 19 may always be re-positioned if necessary, by re moving the rules 19 from the plate 13 by means of a knife or chissel. As both the rules 19 and the plate 13 are of hardened steel, they are subject to extremely little wear, and may therefore afford long and reliable service.

There may thus be provided, in a surprisin gly simple and effective manner, a die for a creasing machine, which die may be relatively cheap and simple to manufacture, whilst af fording long-term reliable operation, and the facility for re-positioning of the creasing chan nels, as necessary.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel com bination, of the features disclosed in this spe cification and/or drawings, or to any novel one, or any novel combination, of the steps of any method or process disclosed herein.

Claims

1. A die for a creasing machine, the die comprising a plate and at least one rule which is secured to the plate and is formed with a channel which is adapted to receive a creasing knife such that, in use, a blank may be placed between the rule and the knife and creased by engaging the knife in the channel, both the plate and the rule being of hardened steel and the rule being secured to the plate by means of a cured adhesive which substantially pre vents relative movement between the rule and the plate.

2. A method of manufacturing a die for a creasing machine, comprising the steps of coating at least one hardened steel rule with a curable adhesive which, when cured, is substantially solid, applying the adhesive-coated rule to a hardened steel plate, and allowing the adhesive to cure such that it then substantially prevents relative movement between the rule and the plate, the rule being adapted to receive a creasing knife such that, in use, a blank may be placed between the rule and the knife and creased by engaging the knife in the channel.

3. A method according to Claim 2, wherein the rule is firstly engaged on a respective creasing knife and the knife is subsequently urged towards the plate, thereby to press the adhesive-coated rule against the plate.

4. A method according to Claim 2 or 3, including the step of applying heat to the adhesive to promote curing thereof.

5. A method according to Claim 4, wherein heat is applied to the adhesive via the knife and/or the plate.

6. A method according to Claim 5, wherein the knife or a holder therefor incorporates a heating element, to apply heat to the adhesive via the knife.

7. A method according to any one of Claims 2 to 6, wherein the adhesive comprises an epoxy resin.

8. A die or method according to any preceding claim, wherein the rule comprises one element of a matrix of rules, adapted to cooperate with a corresponding matrix of creasing knives.

9. A die for a creasing machine, substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

10. A method of manufacturing a die for a creasing machine, substantially as hereinbefore described.

11. A creasing machine incorporating a die according to, any preceding claim or manufactured in accordance with a method according to any preceding claim.

12. A creasing machine according to Claim 11, incorporating at least one cutting knife adapted to cooperate with the plate to cut a blank simultaneously with a creasing operation.