GB2195282A

GB2195282A - Sheet separating apparatus

Info

Publication number: GB2195282A
Application number: GB08720796A
Authority: GB
Inventors: Michael William Beer
Original assignee: EUROBOND
Current assignee: EUROBOND
Priority date: 1986-09-17
Filing date: 1987-09-04
Publication date: 1988-04-07
Anticipated expiration: 2007-09-04
Also published as: GB8622369D0; GB2195282B; GB8720796D0

Abstract

The apparatus 1 comprises:- a pair of spaced apart, parallel side frames defining between them a feed for stock to be separated; a guide member 15 extending transversely of the side frames and above the bed; at least one carriage 16 mounted for positional adjustment along the member 15; a bursting knife 19 mounted on the or each carriage 16; power means, to operate the bursting knife 19, mounted on the or each carriage 16; and means to control synchronised actuation of the power means in accordance with the rate of linear feed, in use, of stock along the bed and the length of artwork sheets, e.g. bookcovers, within the stock, the control means including transducer means 11, 22 capable of detecting overlapped end portions of successive artwork sheets. The book covers etc. are connected by a plastics film 7 applied in a laminating machine and the or each knife is actuated to tear the edge(s) of the film 7 at the overlap. The control means then actuates rollers 11 to tension the stock and propagate the tear across the whole stock width. <IMAGE>

Description

SPECIFICATION Sheet separating apparatus This invention relates to a sheet separating apparatus to divide up stock from a continuous length-usually stored in reel form-into individual sheets, particularly for use in separating laminated stock and used in conjunction with a laminating machine.

In the laminating process, a continuous length of transparent synthetic plastics film material is applied, by adhesive, to a succession of sheets in the form of individual items of artwork such as book jackets, record sleeves etc., to give a protective, glossy effect to the artwork.

A known sheet separating apparatus is described in GB 2137597 and comprises a pair of spaced-apart side frames with a bursting knife mounted on one side frame and projecting inwardly so as to be capable, when activated, of bursting/cutting/tearing the edge of the plastics film, with the rear then propagated across the full width of the plastics film without distorting the laminate and without stressing the bond, by pairs of pinch rollers having a speed differential compared with the operational speed of the laminating machine, through which rollers the stock passes, with transducers being employed to sense the presence and absence of artwork and hence to synchronise the activation of the bursting knife.

Such a known separating apparatus can be improved in several respects.

Firstly, with a single edge tear, there is a limit to the stock width across which a tear can be propagated satisfactorily, the width being circa 32", for at such greater widths, greater propagation forces are required with the attendent propensity for laminate distortion, as well as a requirement for engineering increases as far as shafts, bearings drive motors etc are concerned.

Secondly, when the separating apparatus is used in conjunction with a laminating machine, the relatively limited speed of operation of the separating apparatus restricts the operational speed of the laminating machine.

Thirdly, for any given width of laminating machine/separating apparatus, the stock width may be considerably less and for various reasons, the maximum range of bursting knife lateral position adjustment is 2.5", causing difficulties with relatively narrow stock, and/or an incapability of separating some stock widths with existing equipment.

Fourthly, a highly popular plastic film, polyester, is not amorphous so that the maximum film width across which a cut or tear can be propagated is 12" to 14".

Fifthly, the drive to know separating apparatus has been by chain from a drive motor, requiring the presence of a right angle gearbox, a single revolution clutch, and highly accurate machining and adjustment of the individual components, hence resulting in substantial production and other costs.

The object of the present invention is to provide a sheet separating apparatus in which the above drawbacks are obviated, if not eliminated, capable of operating at substantially higher throughput speeds and with a burst point selectable across the full width of the machine.

According to the present invention, there is provided a sheet separating apparatus comprising: a pair of spaced apart, parallel side frames defining between them a bed for the passage of stock to be separated; a guide member extending transversely of the side frames and above the bed; at ieast one carriage mounted on the guide member and positionally adjustable along the guide member; a bursting knife mounted on the or each carriage and above the bed; power means to operate the bursting knife also mounted on the or each carriage; and a control means to conrol synchronised activation of the power means in accordance with the rate of linear feed, in use, of stock along the bed of the separating apparatus and the length of artwork sheets within the stock, the control means including transducer means capable of artwork sheet detection.

Preferably, the guide member is in the form of one or more rods or bars extending across the side frames and attached thereto, with the bed constituted by a plurality of endless conveyor bands e.g., of plastics or, rubber, to convey the stock to the or each bursting knife.

Conveniently, the carriage has one or more apertures or yokes of profile corresponding to the cross section of the guide member(s) and has clamping means, preferably in the form of a screw arrangement whereby the carriage may be is clamped in a user selected position along the guide member(s).

In detail, two or even three individually adjustable carriages may be provided, and these may be mounted on a common guide member(s).

The bursting knife may be mounted on one end of a drive shaft for rotation in a plane at right aniges to the direction of movement of stock, in use, through the bed of the apparatus.

Conveniently, power means in the form of an electric motor is drivably attached to the other end of the shaft. If in accordance with a preferred mode the knife motors are driven continuously, a one revolution clutch/brake is interposed between each motor and knife drive shaft. In detail, the motor may be a D.C.

shunt wound, geared motor. Alternatively a servo motor or a stepper motor could be em ployed.

The sheet separating aparatus preferably also incorporates means to sense the presence of artwork sheets, such as a pair of cooperating rollers defining a nip between adjacent peripheries to pinch the stock between the sensing rollers, with one roller displaceable upon an artwork sheet entering or leaving the nip. These sensing or pinch rollers are preferably continuously driven from a main (electric) motor.

The transducer means of the control means may conveniently comprise a contactless proximity sensor if the apparatus is provided with a pair of pinch rollers, one of which is displaceable upon the leading edge of an artwork sheet entering the nip and a trailing edge leaving the nip, with the sensor sensing upward and downward roll movements respectively, upon entry and exit of an artwork sheet, and producing output signals to a control circuit of the control means to cause duly synchronised on and off switching of the knife drive motor(s), or engagement/disengagement of the single revolution clutches and hence activation of the bursting knife/knives.

The sheet separating apparatus preferably also incorporates a pair of constant speed drive rollers to drive the stock through the apparatus, the latter preferably also incorporating, downstream of the bursting knife/knives, a set of bursting rollers rotatable at a greater speed than the constant speed rollers.

The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the apparatus in accordance with the invention; Figure 2 is an enlarged view of one bursting knife portion of Fig. 1; Figure 3 is an end elevation of Fig. 2, and Figure 4 illustrates diagrammatically a control circuit.

In the drawings is Illustrated a sheet separating apparatus 1 for separating or dividing up stock stored as a reel 2, the stock comprising individual sheets of paper artwork, with the trailing edge 3 of one sheet 4 overlapped with the leading edge 5 of the next succeeding sheet 6, and with a thin layer of transparent synthetic plastics film 7 bonded to the overlapped sheet edges, in the conventional manner, by a laminating machine.

A bed for the support and conveyance of the stock is presented by a first pair of rollers 8 serving to sense the increase in thickness at an overlap; an intermediate support roller 9; a pair constant speed rollers 10, one located above the stock and one located below the stock to grip the latter and thereby drive the stock through the apparatus 1, the stock being pulled from the reel 2; a set of bursting rollers 11, one located above what then becomes individual laminated sheets, and one located below the laminated sheets, and rotatable at a greater speed, e.g. 125% of the constant speed rollers 10; a further support roller 12 also rotatable at the higer speed; and a plurality of endless conveying bands 13 of rubber or plastics, indicated only in part.The rollers 8 and 10 are rotatably supported from a pair of spaced-apart side frames (not shown) while the rollers 11 and 12 are supported on a movable frame 14, with suitable chain, geared or other drives (not shown) to the various rollers.

Above the bed is a guide member in the form of a bar 15 extending transversely of the bed and side frames, and slidably adjustable along the bar 15 are two carriages 16 adapted to be located one in the vicinity of each lateral edge of the stock, each carriage 16 having a yoke 17 of profile corresponding to that of the bar 15, and screw clamping means 18, whereby each carriage 16 may be clamped in a user-selected position along the bar 15. Each carriage 16 is also provided with a bursting knife 19 mounted on one end of a drive shaft 20 and movable between active and non-active positions by a D.C. shunt wound electric motor located within a housing 21 also attached to the carriage 16. In detail, the electric motor is attached to the other end of the drive shaft 20 via a conventional one revolution clutch/brake.

The knives 19 are activated under electrica I/electronic control circuit illustrated in Fig. 4.

When the rollers 8 sense a "bump" by being momentarily separated, beyond a pre-set gap, to allow for passage of overlapped edges 3, 5, movement of one of the rollers 8 and activates a transducer 22 such as a conventional limit switch, proximity sensor etc., to emit a sheet sensor pulse 23 to a delay device 24.

The latter emits a first delay pulse 25 to engage single revolution clutch units 26 to cause synchronised rotation of their associated knives 19 so that the latter burst the lateral edges of the film 7 in the region of a pair of overlapped edges 3, 5, and also emits a second delay pulse 27 to engage a single revolution clutch unit 28 to cause engagement of the rollers 11 with the stock, whereupon the greater speed of the rollers 11 propogates the cuts or tears effected by the knives 19, to complete sheet separation.

Claims

1. A sheet separating apparatus comprising: a pair of spaced apart, parallel side frames defining between them a bed for the passage of stock to be separated; a guide member extending transversely of the side frames and above the bed; at least one carriage mounted on the guide member and positionally adjustable along the guide member; a bursting knife mounted on the or each carriage and above the bed; power means to operate the bursting knife also mounted on the or each carriage; and a control means to control synchronised activation of the power means in accordance with the rate of linear feed, in use, of stock along the bed of the separating apparatus and the length of artwork sheets within the stock, the control means including transducer means capable of artwork sheet detection.

2. Apparatus as in Claim 1, wherein the guide member is in the form of one or more rods or bars extending across the side frames and attached thereto.

3. Apparatus as claimed in Claim 1 or Claim 2, wherein the bed comprises a plurality of endless conveyor bands to convey the stock to the or each bursting knife.

4. Apparatus as claimed in Claim 3, wherein the bands are of plastics.

5. Apparatus as claimed in Claim 3, wherein the bands are of rubber.

6. Apparatus as claimed in any preceding Claim, wherein the carriage has one or more apertures or yokes of profile corresponding to the cross section of the guide member(s).

7. Apparatus as claimed in any preceding Claim, wherein the carriage has clamping means, preferably in the form of a screw arrangement, whereby the carriage is clampable in a user selected position along the guide member(s).

8. Apparatus as claimed in Claim 7, wherein the clamping means is a screw arrangement.

9. Apparatus as claimed in any preceding Claim, wherein two individually adjustable carriages are provided.

10. Apparatus as claimed in any one of Claims 1 to 8, wherein three individually adjustable carriages are provided.

11. Apparatus as claimed in Claim 9 or ClaimlO, wherein the carriages are mounted on a common guide member.

12. Apparatus as claimed in any preceding Claim, wherein the or each bursting knife is mounted on one end of a drive shaft for rotation in a plane at right angles to the direction of movement of stock, in use, through the bed of the apparatus.

13. Apparatus as claimed in Claim 12, wherein power means in the form of an electric motor is drivable attached to the other end of the shaft.

14. Apparatus as claimed in Claim 13, wherein the knife motors are driven continuously and a one revolution clutch/brake is interposed between each motor and a knife drive shaft.

15. Apparatus as claimed in Claim 13 or 14, wherein each knife motor is a D.C. shunt wound, geared motor; a servo motor; or a stepper motor.

16. Apparatus as claimed in any preceding Claim, incorporating means to sense the presence of artwork sheets.

17. Apparatus as claimed in Claim 16, wherein the sensing means comprises a pair of co-operating rollers defining a nip between adjacent peripheries to pinch the stock between the sensing rollers, with one roller displaceable upon an artwork sheet entering or leaving the nip.

18. Apparatus as claimed in Claim 17, wherein the sensing or pinch rollers are continuously driven from a main electric motor.

19. Apparatus as claimed in Claim 16, when appendant to Claim 13, 14 or 15, wherein the transducer means of the control means comprises a contactless proximity sensor to sense upward and downward roller movement respectively, upon entry and exit of an artwork sheet, and producing output signals to a control circuit of the control means to cause duly synchronised activation of the bursting knife/knives.

20. Apparatus as claimed in any preceding Claim, comprising a pair of constant speed, drive rollers.

21. Apparatus as claimed in Claim 20, comprising downstream of the bursting knife/knives a set of bursting rollers rotatable at a greater speed than the constant speed rollers.

22. A sheet separating apparatus substantially as hereinbefore described with reference to the accompanying drawings.