GB2288563A

GB2288563A - Die cutting blanket

Info

Publication number: GB2288563A
Application number: GB9508060A
Authority: GB
Inventors: Mohan Mclelland; Michael Berwick
Original assignee: Scapa Group Ltd
Current assignee: Scapa Group Ltd
Priority date: 1994-04-21
Filing date: 1995-04-20
Publication date: 1995-10-25
Also published as: AU2262995A; GB9407877D0; WO1995029047A1; GB9508060D0

Abstract

A die cutting blanket 10 is wrapped around a roller 18 and co-acts with a die cutting roller to cut out pieces from corrugated board which is passed between the rollers. The blanket 10 comprises a fabric layer 12 onto which is cast a polymeric layer 11. One end of the blanket has a projection 13 which is fixed into a channel 14 of an aluminium block 15.The blanket is wrapped around the roller and brought into endless form by inserting a tongue 17, at the other end of the blanket, into a second channel 16 in block 15. The fabric layer 12 extends into the tongue 17 (Fig 3a) and may be looped (Fig 3b). The woven fabric may be replaced by a plurality of intermeshing spiral coils (20, Fig 3c). <IMAGE>

Description

DIE CUTTING BLANKET The present invention relates to die cutting blankets.

Die cutting blankets are used in the manufacture of corrugated board products. The board passes through a nip created by a roller clad with die cutting blankets and a roller onto which are attached a series of dies.

Dies are specifically shaped pieces of metal which cut through the board, thereby allowing board elements of the desired shape to be obtained. The dies are usually always arranged such that they never cut closer than 1 inch to the die cutting belt seam.

One known die cutting blanket comprises a perforated backing made of mild steel, at one end of which is welded a metal square section U-shaped channel.

A polyurethane coating is applied to the upper surface of this, and following the coating process a cast tongue is produced. This tongue is then hammered into the metal channel to render the belt endless during installation on the cutting machine.

The resultant clad cutting cylinder receives the intermittent pressure and severance of the cutting dies.

Each belt is about 10.5" (26.7cm) wide, with each cutting cylinder being clad with a 'set' of about 8 to 13 blankets. The middle section blankets see most usage and after a while are therefore uncoupled and moved to the outer positions, with the relatively undamaged outer blankets being relocated to the middle section. Depending on the severity of use, it is normal for one cutting cylinder to be re-clothed 10 to 20 times per year.

The metal perforated backing of these die cutting blankets is heavy, expensive and prone to rust.

The present invention has been made from a consideration of this problem.

According to the present invention there is provided a die cutting blanket comprising a fabric layer in combination with a layer of polymeric material, the die cutting blanket further comprising means for connecting the two ends of the blanket so as to provide an endless structure.

The fabric is preferably woven, or possibly knitted, and may be made from any suitable material such as polyester, polyamide or other high tensile yarns. The fabric may comprise an inorganic material such as metal or glass.

Alternatively the fabric may be of a type such as that described in US 4675229, i.e. formed from a plurality of intermeshing spiral coils, usually of plastics material, interconnected by hinge yarns. The two ends of the fabric may be connected together.

The fabric is ideally of an open construction in order to avoid air entrapment problems during casting. The fabric prevents stretching of the blanket when the blanket is in use.

The polymeric layer preferably comprises polyurethane, or natural or synthetic rubber. The polymeric layer is preferably cast onto and into the fabric.

The means for connecting the two ends of the blanket may comprise a tongue engageable with a channel.

Notches may be provided in the tongue in order to make the tongue more flexible and more easy to install in the channel. The fabric preferably extends into the channel and terminates in a loop disposition. The loop termination is preferred as pins may be inserted therein, thereby increasing the fabric-polymer contact area, thus improving "adhesion" of the polymer to the fabric. The channel may be formed in a block formed integrally with or connected to the other end of the belt. The block may be made from metal.

In order that the present invention may be more readily understood specific embodiments thereof will now be described by way of example only with reference to the accompanying drawings in which: Fig.l is a side elevation of one die cutting belt in part in accordance with the present invention; Fig.2 is a side elevation of the die cutting belt of Fig.l when in use; and Fig.3 shows cross sections of three alternative die cutting belts in accordance with the present invention.

Referring to the drawings a die cutting belt 10 comprises a polyurethane layer 11 cast onto a polyester woven fabric 12. A projection 13 depends from one end of the belt. The projection is permanently fixed to one channel 14 provided in a steel or aluminium block 15.

The block further comprises a second channel 16 which is operative to receive a tongue 17 depending from the other end of the belt 10. When the tongue is secured in this second channel 16 the belt 10 is brought into endless form. This tongue 17 may be removed from the second channel 16 in order to remove the belt 10 from the roller 18 on which it is located when in use. If the belt 10 is to be relocated on a different section of the roller 18 the tongue 17 may once again be located in the second channel 16 once the belt 10 has been repositioned.

The fabric 12 preferably extends into the tongue as shown in Fig.3a. The end of the fabric is preferably formed into a loop 19 as shown in Fig.3b. A pin may be inserted in the loop.

In Fig.3c the woven fabric has been replaced with a plurality of intermeshing spiral coils 20 with adjacent coils being interconnected by hinge yarns.

Here the two ends of the belt are joined with the metal channel as before, but the joint is further strengthened by temporarily connecting the two ends of the fabric.

This may be achieved by connecting the coils at each end of the fabric with a relatively large pintle wire 21 having a high degree of lubricity, that is readily rejecting polyurethane adhesion. As the polyurethane enters the nearly cured green state the oversized pintle wire is withdrawn. As the polyurethane hardens the gap created by the removal of the pintle wire diminishes in size thereby allowing a smaller pintle wire to be inserted to join the two ends of the fabric.

It is to be understood that the above described embodiment is by way of illustration only. Many modifications and variations are possible.

Claims

1. A die cutting blanket comprising a fabric layer in combination with a layer of polymeric material, the die cutting blanket further comprising means for connecting two ends of the blanket so as to provide an endless structure.

2. A die cutting blanket as claimed in claim 1, wherein the said fabric layer is woven.

3. A die cutting blanket as claimed in claim 1, wherein the said fabric layer comprises a plurality of intermeshing spiral coils interconnected by hinge yarns.

4. A die cutting blanket as claimed in any preceding claim, wherein the two ends of the fabric are connected together.

5. A die cutting blanket as claimed in any preceding claim, wherein the layer of polymeric material is cast onto and into the fabric.

6. A die cutting blanket as claimed in any preceding claim, wherein the polymeric material comprises polyurethane or rubber.

7. A die cutting blanket as claimed in any preceding claim, wherein the means for connecting the two ends of the blanket comprises a tongue engageable with a channel.

8. A die cutting blanket as claimed in claim 7, wherein notches are provided in the tongue.

9. A die cutting blanket as claimed in claim 7 or claim 8, wherein the said fabric layer extends into the channel.

10. A die cutting blanket as claimed in any of claims 7 to 9, wherein the fabric terminates on a loop disposition.

11. A die cutting blanket as claimed in claim 10, wherein a pin is inserted in the loop.

12. A die cutting blanket as claimed in any of claims 7 to 11, wherein the channel is formed in a block, the block being formed integrally with or being connected to the other end of the blanket.

13. A die cutting blanket as claimed in claim 12, wherein the block is formed from metal.

14. A die cutting blanket substantially as described herein with reference to Figs. 1 and 2 or Figs. 3a, 3b or 3c.