WO1991017871A1

WO1991017871A1 - Improved cutting die

Info

Publication number: WO1991017871A1
Application number: PCT/AU1991/000211
Authority: WO
Inventors: Steven Ryder; Silvano Adam Forlani
Original assignee: Rota Die Pty. Ltd.; Amcor Limited
Priority date: 1990-05-17
Filing date: 1991-05-17
Publication date: 1991-11-28

Abstract

A die (30) for a rotary die cutting machine (10). The die has cutting knives (23) and creasing knives. Stripping members (24) are present. Member (24) has rods (22) secured thereto. The rods (22) may be contacted by cam (13) to move member (24) past retaining pins to cause material cut to form a blank to be stripped from the blank.

Description

"IMPROVED CUTTING DIE" THIS INVENTION relates to an improved die for cutting a container blank from fibreboard material. In particular, the invention concerns an improved die for producing a container blank in rotary die cutting machine.

Die cutting machines fall into two broad categories; flat bed die cutters and rotary die cutters. Rotary die cutters are subdivided into two further categories - soft cut and hard cut machines. The die of the invention is intended for use within rotary die cutters.

Hard cut die cutters have a die drum to which a die is mounted and a steel anvil drum. Fibreboard material is fed between these rotating drums to produce a resultant blank. A soft cut die cutter is similar except that the anvil drum is provided with a polyurethane outer covering or blanket.

Cutting dies are typically provided having a substrate of wood or plywood to which are mounted cutting knives or cutting rules which, in use cut through the fibreboard material to define the outer periphery of the blank and also in many cases form slots or apertures in the blank itself in the case of blanks intended to form cartons for produce or cartons with integral carry handles or the like.

In addition the die may also have further rules for forming crease lines in the blank between

SUBSTITUTESHEET adjacent panels. Also, scoring rules for providing perforations may be mounted to substrate.

The die typically is arcuate in profile to suit the curvature of the die drum to which it is mounted and may consist of several arcuate die sections which together form a complete blank. Sometimes the die or die sections may be constructed to simply form one blank for a single rotation of the die drum or several blanks for a single rotation. The die drum consists of an outer cylindrical drum mounted for rotation about its longitudinal axis. This drum is provided with a plurality of apertures in a grid like pattern. The apertures are alternately threaded and unthreaded and typically a spacing of 50 mm exists between the unthreaded apertures. The threaded apertures facilitate the mounting of dies or die. sections to the drum. The unthreaded apertures are necessary in the stripping of waste material from the fibreboard material after the die has cut the blank from the material. This waste stripping aspect will be described below.

A cam is located within the outer drum. This cam consists of an eccentrically mounted stationary cylinder. It is important that waste material cut from the periphery of the blank, resulting from slots cut into the blank or from apertures cut into the blank be removed from the blank and the die itself. The waste

SUBSTITUTESHEET should not be discarded at the point of cutting and should be held or retained until the section cut by the die has moved before removal or stripping of the waste is carried out. The build-up of waste and dust resulting from the cutting operation is undesirable and can lead to cutter machine down time for facilitating cleaning of the knives and may even result in damage of the knives. Uncontrolled stripping is undesirable as waste may then be ejected along with the finished blank. In one earlier die an attempt was made to provide for stripping of waste both externally and internally of the blank. This involved providing the die with a stripping plate mounted to the substrate via a hinge. The free edge or end of the plate was either provided with a stripping finger which formed an integral extension or was formed with one or more attachment fingers to which a separate stripping member was mounted. It was also sometimes the practice to have a retaining member or pin adjacent the plate. The pin would spike the waste to retain it for stripping from the die at a desired instant in the formation of the blank although such pins were not always used. The plate was caused to hinge by a push rod which was positioned in one of the unthreaded apertures in the outer drum of the die drum. The push rod would be caused to move by the cylindrical cam upon rotation of the die drum and the plate would be caused to pivot.

Such hinge plate waste stripping was

SUBSTITUTESHEET particularly labour intensive to set up because of the hinging requirement. In addition the stripping finger or stripping member did not move up square relative to the knives and stripping was often not achieved. If a retaining pin was not present premature ejection of the waste was a possibility.

The hinge plates and stripping members were made of metal and time consuming machining operations were necessary to produce the desired shapes. The hinging or pivoting action caused the stripping finger or the attachment finger(s) to fatigue, break off and release the plate to freely pivot relative to the substrate. This often occurred and required the die to be repaired. Worse still, the plate sometimes pivoted over one of the knives and a subsequent rotation of the drum then caused the anvil drum to press the plate against the knife and damage the knife. The stripping member could also come adrift and damage the knives. If such damage occurred, the cutter machine would need to be stopped and the damage repaired.

The stripping hinge plates were metallic, specially shaped expensive to make and mount and lacked flexibility. Build-up of waste still occurred and this caused damage to the knives and plate. A subsequent development on the hinge plate stripping referred to above involved replacing the metallic stripping member with a member made of plastic material. This ensured that the member itself no longer

SUBSTITUTESHEET caused damage if it came adrift and was easier to make but did not eliminate any of the other disadvantages of the hinge plate stripping arrangement mentioned above.

According to one aspect the present invention provides a die for cutting a container blank from fibreboard material in a rotary die cutting machine having an apertured die drum and a cylindrical cam within the drum, the die including cutting knives defining at least a periphery of a blank and having a plurality of stripping members made of plastics material at spaced locations corresponding to the periphery of the blank, each said member having at least one rod integral therewith or secured thereto mountable relative to an aperture in the drum for movement relative to the drum by the cam to thereby directly move the member radially relative to the drum to eject waste material away from the knives and a retaining pin adjacent at least one said stripping member for holding the waste material after the blank has been cut and until the waste is stripped from the die.

The die of the invention may include cutting knives defining cut outs or apertures in the blank. Where the die has such knives it is preferred that at least one internal cut out or aperture have at least one stripping member of plastics material. The or each internal stripping member has at least one rod integral therewith or secured thereto for reception by the die drum. Preferably the die has an internal stripping

SUBSTITUTESHEET member associated with each cut out or aperture. Each member may have a retaining pin mounted to the substrate and adjacent the member.

The rods associated with the internal stripping members are preferably longer than the rods associated with the external stripping members although this need not be the case.

The rods are preferably adapted so that they are retained relative to the aperture in the drum to which they are fitted. Each rod may have a retaining member to achieve this. Preferably the retaining member is a deformable member secured to the rod. In one embodiment the rod has a deformable pin mounted adjacent the end distant from the member and which extends outwardly beyond the rod.

The external stripping members preferably have at least a bevelled leading edge and may have a bevelled trailing edge to better facilitate stripping of waste during rotation of the die drum. The internal stripping members preferably have a peripheral shape conforming to the shape defined by the cutting knives which form apertures or cut outs in the blank. Thus where the cut outs are intended to be elongate substantially rectangular cut outs the members have a corresponding rectangular shape. Where the cut ours are circular the members have a circular shape. Other shapes may also be employed.

The retaining pins associated with internal

SUBSTITUTESHEET stripping members may comprise short studs projecting outwardly from and secured or mounted to the die substrate.

The studs have a leng2h greater than the thickness of the stripping members such that they normally extend beyond the member and adjacent knife to spike and hold waste prior to stripping. The degree of travel of the stripping member is greater than the length of the stud such that the member may cause waste held by the stud to be freed from the stud. The stud may have an end which defines a point. Preferably the stud is either threaded along its length or has a wasted portion to assist in retaining waste. Preferably studs located internally of the peripheral knife are threaded while the studs located externally are provided with a pointed end and an intermediate wasted portion.

The die may also' include a plurality of creasing rules for forming fold lines between adjacent panels of the blank. Where creasing rules are present it is preferred that strips having an inclined upper surface be positioned adjacent each side of the rule such that there be a gradual slope up to the outermost periphery of the creasing rule. This ensures that the fibreboard material is not unduly impeded in its passage between the die drum and anvil drum. The strips are preferably made of plastics material.

The die may have one or more scoring rules for producing a line of perforations along the blank if

SUBSTITUTESHEET desired .

Resilient strips or blocks may be positioned at intervals on the die to assist in stripping of both the waste and separation of the blank from the die. The resilient strips or blocks are preferably positioned closely adjacent the cutting knives or rules which are provided on the die. The strips or blocks may be made of resilient rubber material or any other suitable material. A particular preferred embodiment of the invention will now be described by way of example with reference to the drawings in which:

Figure 1 is a diagrammatic view of a die drum ^' and anvil drum of a rotary die cutting machine; Figure 2 is an enlarged fragmentary view of part of the die drum shown in Figure 1;

Figure 3 is a perspective view of three die sections comprising a die according to an embodiment of the invention; Figure 4 is an enlarged fragmentary view of the die of Figure 3;

Figures 4a, 4b and 4c show enlarged detail views of parts of the die of Figure 3.

Figure 1 shows a diagrammatic view of a rotary die cutting machine 10 having a die drum 11 and an anvil

12 both mounted for rotation. The drum 11 has within it a stationary cam member 13 and die sections 14, 15 and

16. Die sections 14, 15, and 16 together comprise a die

SUBSTITUTESHEET for making a blank from fibreboard material 17 fed between the anvil 12 and drum 11. The die sections comprise an arcuate wooden substrate to which are mounted cutting and creasing knives or rules and other components for making the desired blank configuration.

In Figure 2 the die drum 11 is shown having apertures through it. Threaded apertures 20 can be employed for securing die sections to the drum while the unthreaded apertures 21 receive rods 22 for moving stripping members 24 relative to the cutting knives 23. As shown in this figure the member 24 has two rods 22 for causing it to move relative to the knife 23 to strip waste cut from the material away from the knife. This stripping occurs when the free ends of the rods 22 contact cam member 13 (see Figure 1) and the member 24 then moves radially relative to the drum 11.

Each rod has a head 25 facilitating attachment to member 24 and a waisted free end 26 which carries a' resilient member 27 which extends laterally beyond the rod. Member 27 is deformed during insertion of the rod into an aperture 21 and ensures that the rod is retained relative to the drum 11 during rotation of the drum.

Figure 3 shows a typical die 30 comprising three arcuate die sections 31, 32, 33, each section has hand holes 34. In this instance the die is configured to produce two identical slotted container blanks from a sheet of fibreboard material. Cutting knives 35 extend around the periphery defined by the two adjacent blanks

SUECTBTUTESHEET formed by the die while knife 36 severs the material between the two adjacent blanks formed by the die sections. Short cutting knife sections 37 (only some of them have been identified by a numeral) extend outwardly from the peripheral knife 35. Sections 37 ensure that the peripheral waste material is cut into short lengths suitable for handling and recycling. The die has creasing knives or rules 38 for forming crease lines between adjacent flaps or panels of the blank made by the die. In addition the die has resilient blocks 39 at various locations around the peripheral knife 35 and knife 36. Waste stripping members 40, 41, 42 are arranged around the knife 35 while stripping members 43 are positioned adjacent knife 36. Holes 44 at various locations facilitate the mounting of sections 31, 32, 33 to the drum 11.

Figure 4 of the drawings shows greater detail of a portion of a die according to an embodiment of the invention. Part of the peripheral knife 35 on section 33 is shown with short knife sections 37 extending therefrom. The creasing knives 38 are ramped to an apex and the apex may be provided by a metal creasing rule while the ramped portions may be provided by profiled strips typically of plastics material. Each of the waste stripping members consists of a plastic stripping member and rods extending through the die section substrate. Stripping member 40 has inclined opposed edges 50 which, in use extend along

SUBSTITUTESHEET drum 11 and a notch 51 at one end adjacent knife 35. A retaining pin like that shown in either Figures 4a or 4b extends outwardly from the substrate of section 33 and is located in the notch 51. It is preferably that a pin like that of Figure 4b be used in this location. Pins of Figures 4a and 4b pierce the material and hold the waste until it is stripped by the waste stripping members . The pins are fixed to the substrate and the stripping members normally extend beyond the stripping members. Similarly stripping member 42 has a notch 52 and member 41 has a notch 53. It is not necessary that each stripping member be associated with a retaining pin but it is preferred.

Stripping member 42 has an inclined edge 54 and a finger 55. Finger 55 extends between those parts of the knife 35 which defines the slot between adjacent parts of the die which form closure flaps of the blank. The remainder of the slot has a length of resilient material 56 placed within it. Material 56 is the same as that employed for blocks 39 and serves to assist in waste stripping. Stripping member 41 has a notch 53 with a pin located in it and inclined edge 56.

All of the stripping members can be moved away from the substrate of the die when the rods 22 contact cam member 13. This causes the stripping members to move true relative to the knives for stripping waste away from the knives and from the blank cut from the fibreboard material by the die.

SUBSTITUTESHEET Figures 4a and 4b show portions of the die 30. The substrate 14 has pin 60 or 61 mounted to it to extend through the above stripping member 62. The free end of each pin may pierce the fibreboard material 17 during cutting and creasing. Movement of the member 62 when rods 22 (not shown) strike cam member 13 causes waste material to be moved off the pins. Pin 60 is a light duty pin and is threaded and typically would be used for retaining waste cut from within the periphery of the blank. Pin 61 is a heavy duty retaining pin and typically would be used for retaining waste cut from outside the periphery of the blank. Pin 61 has a pointed end 63 and a waisted portion 64.

Not all stripping members require retaining pins to be associated with them. As shown in Figure 4c stripping members 43 are employed to strip waste cut. from slots between adjacent closure flaps formed in adjacent blanks. Members 43 are relatively narrow and retaining pins are not generally necessary in such cases.

It is not necessary for the improved die of the invention to have all stripping members constructed as discussed where they are directly moved by the provision of rods. It may be that at the location where stripping is required there is no conveniently located hole 21 for receiving a rod 22. In which case at that location stripping may still be effected by utilizing hinged plate stripping members of the prior art. A die with stripping members as discussed is relatively quickly set up and thus the labour component in the die setting up time is greatly reduced. Since the stripping members are made of plastic, costly and time consuming metal machining and shaping operations have been eliminated. Waste is more positively stripped using the die of the invention and the incidence of knife damage or unwanted or mistimed stripping are reduced. It is no longer necessary to cut slots in the sides of the knives to enable hinge plates to drive the stripping members and if the stripping member of the improved die were to come adrift damage to the knives is unlikely because the members are made of plastic material. The die of the invention reduces cost of die manufacture, increased productivity and output and reduces set up time.

SUBSTITUTESHEET

Claims

1. A die for cutting a container blank from fibreboard material in a rotary die cutting machine having an apertured die drum and a cylindrical cam within the drum, the die including cutting knives defining at least a periphery of a blank and having a plurality of stripping members made of plastics material at spaced locations corresponding to the periphery of the blank, each said member having at least one rod integral therewith or secured thereto mountable relative to an aperture in the drum for movement relative to the drum by the cam to thereby directly move the member radially relative to the drum to eject waste material away from the knives and a retaining pin adjacent at least one said stripping member for holding the waste material after the blank has been cut and until the waste is stripped from the die.

2. The die of Claim 1 including knives defining' cut outs or apertures in the blank.

3. The die of Claim 2 wherein at least one of the aperture/cut out defining knives has an associated said stripping member.

4. The die of Claim 2 wherein each said aperture/cut out defining knife has an associated said stripping member.

5. The die of Claim 3 or 4 wherein the or each said stripping member has a retaining pin mounted adjacent thereto and to the substrate.

6. The die of any one of Claims 3 to 5 wherein the rod of the stripping member associated with the aperture/cut out knives is longer than the rod of the stripping member associated with the knives defining the periphery of the blank.

7. The die of any one of Claims 1 to 6 wherein the or each said rod is retained relative to the drum.

8. The die of Claim 7 wherein the or each said rod has a deformable retaining member adjacent one end thereof.

9. The die of any one of Claims 1 to 8 wherein the stripping members associated with the knives defining the periphery of the blank have bevelled leading edges.

10. The die of Claim 9 wherein said stripping members associated with the knives defining the periphery of the blank have bevelled trailing edges.

11. The die of any one of Claims 1 to 10 wherein the or each retaining pin comprises a short stud projecting outwardly from the substrate.

12. The die of any one of Claims 1 to 11 wherein said pins are externally threaded.

13. The die of any one of Claims 1 to 12 wherein said pins have a pointed free end and a reduced width portion spaced from the pointed end.

14. The die of any one of Claims 1 to 13 including creasing rules for forming fold lines between adjacent panels of the blank.

15. The die of Claim 14 including inclined strips adjacent each side of the creasing rule.

16. The die of any one of Claims 1 to 15 including at least one scoring rule.

17. The die of any one of Claims 1 to 16 including resilient strips or blocks at spaced locations to assist in stripping waste from the blank and in separating the blank from the die.

18. The die of Claim 17 wherein the resilient strips or blocks are positioned closely adjacent the cutting knives.

S_UBS_TITUTESHEET