GB2032322A - Cutting and creasing of blanks of cardboard or the like - Google Patents

Abstract

A flat-bed die for use in cutting and creasing a blank comprises a sheet of plywood having an operative surface 1 carrying a pattern of cutting and creasing knives 2. A sealing strip 9 is applied to the surface 1 adjacent the blades to form a continuous seal around the periphery of areas 3 and 4 corresponding to panels and flaps of the blank. At least one aperture 8 is formed through the die within each area 3 or 4. In use, a blank is held in registry with the die during the forming operation by applying suction to the blank through the apertures 8. <IMAGE>

Description

SPECIFICATION Cutting and creasing of blanks of cardboard or the like This invention relates to improvements in or relating to the cutting and/or creasing of blanks of cardboard, fibreboard and the like.

A known apparatus for cutting and creasing such blanks employs a so-called flat-bed die in the form of a solid sheet of plywood having an operative surface provided with a pattern of cutting and creasing knives according to the desired pattern of cuts and creases with which the blank is to be formed. These knives are strip-like steel blades fixed in saw cuts made in the operative surface of the die so as to project from the operative surface in their width direction.

In use, a blank is cut and creased on the known apparatus by placing the blank on the die in contact with the operative surface of the die, and conveying the die and the superposed blank through the nip of co-operating impression rolls which force the blank and die together so that the blades of the die cut and crease the blank.

A major problem in this known apparatus is that of ensuring that the blank is maintained properly registered with the die as they pass between the impression rolls. If this is not the case, then clearly the cuts and creases will not be made in the required places on the blank.

The known flat-bed die is provided with short, spaced-apart lengths of rubber strip positioned adjacent to the cutting and creasing blades to prevent the material being cut from becoming wedged in between the blades and also to provide resilient pressure on the blank away from the die so that the blank can be readily ejected from the die after cutting and creasing.

It is an object of the invention to improve the holding down of the blank during cutting and creasing using a flat-bed die and impression rolls.

Accordingly, the present invention provides a flat-bed die for use in cutting and creasing a blank, the die having an operative surface provided with blades, which die is apertured for transmitting suction therethrough to the operative surface to hold a blank against the die.

More specifically, the invention provides a flat-bed die for use in cutting and creasing a blank, which die comprises a sheet of substantially rigid material having an operative major surface provided with a pattern of projecting blades corresponding to the desired cuts and creases of the blank, in which die an area of the operative surface of the die is enclosed by a resilient sealing strip fixed to the operative surface, and at least one aperture is formed in the die within the said enclosed area so as to place the major surfaces of the die in communication.

In an embodiment of the invention the pattern of blades on the operative surface of the die includes at least one arrangement of blades extending around an area of the operative surface, the resilient sealing strip being fixed to the operative surface adjacent to the blades to enclose the said area, and an aperture being formed in the die within the said enclosed area.

The invention also provides apparatus for cutting and creasing a blank, comprising a die according to the invention, a pairofjuxtaposed impression rolls defining a nip therebetween, conveying means for feeding the die and a superposed blank through the nip of the impression rolls, and suction means for applying suction through the apertured die to the operative surface of the die as the die and blank are conveyed through the impression rolls.

Conveniently, the conveying means comprises a pair of parallel, spaced-apart belts travelling over a table which has a perforated portion between the two belts, the suction means comprising a suction box disposed beneath the table for applying suction to the apertured die through the perforated portion of the table.

In order that the invention may be readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying illustrations, in which: Figure 1 is a top view of a flat-bed cutting and creasing die embodying the invention prior to fixation of the resilient sealing strip; Figure 2 is a view of a portion of the die of Figure 1, showing the blades of the die in more detail; Figure 3 is a view of a portion of the die, showing the resilient sealing strip applied to part of the die; Figure 4 is a view of the die after the resilient sealing strip has been applied to the whole die; Figure 5 is a view showing a portion of the die of Figure 4 in more detail; and Figure 6 is a diagrammatic side view of a cutting and creasing machine using a die embodying the invention.

Referring to Figures 1 and 2, a flat-bed cutting and creasing die embodying the invention comprises a rectangular sheet of plywood having an operative surface 1 provided with a pattern of cutting and creasing knives 2 according to the desired pattern of panels, flaps and slots of a blankto be formed. Areas such as 3,4 and 5 of the die correspond respectively to panels, flaps and slots of the blank.

The knives 2 are strip-like steel blades fixed in saw cuts made in the operative surface 1 of the die and comprise cutting blades 6, 6' for forming an outer periphery of the flaps and slots and creasing blades 7, 7' for defining crease or fold lines between adjacent panels and flaps. The die is formed with a number of apertures 8 which place the major surfaces of the die in communication, at least one such aperture being formed within each individual area 3 or 4 of the surface 1 which corresponds to a panel or flap of the blank to be formed.

Figure 3 shows a portion of the die after a resilient sealing strip 9 has been applied to part of the die.

The sealing strip 9 comprises a spongy rubber strip having a square cross-section and is adhesively fixed to the operative surface 1 adjacent the blades within the individual areas 3 and 4 of the surface 1 to form a continuous sealing strip around the periphery of each area 3 or 4. Figure 3 also shows a transverse strip 10 across panel area 3 between the two apertures 8, an oval sealing piece 11 of the same material as the strip 9 within a short slot-forming blade 6' and a sealing strip portion 12 around the slot-forming blade 6'. The transverse strip 10 serves to divide the rather large area 3 into two smaller individually sealed areas, this being advantageous for the reasons mentioned later.

Figures 4 and 5 show the cutting and creasing die after the sealing strip 9 has been applied to the entire die. As shown in these Figures, the strip 9 is continuous on both sides of each blade for the majority of blades. However, the blades on the periphery of the pattern only have continuous sealing strips on their inner sides and are provided with discontinuous pieces 13 ofthe same rubber material adjacent their outer sides at distinct places such as corners.

Referring now to Figure 6, apparatus for cutting and creasing a blank comprises a feed mechanism 21 for feeding boards of cardboard, fibreboard or the like to be formed into blanks singly from a stack22 of boards to a first transfer conveyer 23 for placing the board on top of a cutting and creasing die (not shown) carried by an input conveyor 24 with the operative surface of the die uppermost. The die with the superposed board is fed by the input conveyor 24 through the nip of a pair of co-operating impression rolls 25,26 to an output conveyor 27.

A second transfer conveyor 28 picks up the formed blank from the die on the output conveyor 27 and transfers it to a discharge conveyor 29. A scrap conveyor 43 is provided above the output conveyor 27 to remove scrap pieces of board cut off in forming the blank from the board.

The feed mechanism 21 comprises a combined front stop and side guide arrangement 30 for squaring up a leading end portion ofthe stack 22. A solenoid actuated board stop 31 periodically permits the lowermost board of the stack 22 to be fed below the arrangement 30 to the first transfer conveyor 23 by a pair of parallel, spaced-apart feed belts 32 whose upper runs tranvel over a conveyor table which has a perforated portion between the two belts. A first suction box 33 is arranged beneath the conveyor table so that the lowermost board is held positively against the belts 32 by suction transmitted through the perforated portion of the table. The first transfer conceyor 23 comprises a pair of belts 34 whose lower runs travel over a conveyor table which has a perforated portion between the two belts.A second suction box 35 is arranged above the conveyortable so that the board is fed to conveyor 23 and is pulled up against the belts 34 by suction transmitted through the perforation portion of the table. Afirst cam-operated ejector 36 ejects the board from the first transfer conveyor 23 onto the cutting and creasing die on the input conveyor 24, the latter comprising an upstream portion having a pair of belts 37 and a downstream portion similar to feed conveyor 21 and comprising a pair of belts 37 and a third suction box 38. An adjustable end stop 39 defines an upstream limit of movement for the die. A first side guide 40 provides lateral guidance of the die on both sides of the input conveyor 24 as it is conveyed into the nip of impression rolls 25,26.

As they leave the impression rolls 25, 26, the die and the formed blank are received on an upstream portion of output conveyor 27, which is similar to the downstream portion of input conveyor 24 and comprises a pair of belts 41 and a fourth suction box 42. The board then passes to a pair of belts 41' of a downstream portion of conveyor 27, which is similar to the upstream portion of input conveyor 24 and where the downstream limit of movement is set by adjustable end stop 44. Lateral guidance of the die on leaving the impression rolls is provided by a second side guide 45. The blank is picked up from the die by the second transfer conveyor 28, which is similar to the first transfer conveyor 23 and comprises a pair of belts 46 and fifth and sixth suctions boxes 47 and 48.The blank is ejected onto discharge conveyor 28 by a second cam-operated ejector 50.

On reaching the end of the second transfer conveyor 28 the board is registered in a counter (not shown).

When the counter indicates that, a batch of predetermined number of boards has accumulated on discharge conveyor 28, this conveyor is advanced by half its length, so as to present an empty part of the belt below the transfer conveyor 28 for receiving the next batch.

Scrap pieces cut from the board are conveyed away from the downstream side of the impression rolls 25, 26 by an overhead scrap conveyor 43 which comprises a wire mesh belt 51 and a seventh suction box 52 for drawing the scrap onto the belt 51. The individual sealing pieces 13 around the periphery of the blade pattern of the die enable the severed marginal scrap pieces of the board to be lifted from the die by a back-draught through the apparatus, so that these pieces can be readily picked up by scrap conveyor 43.

In an alternative form of the invention (not shown), the oval sealing pieces 11 of a slot area of the cutting and creasing die are omitted and the areas 5 within the blades 6' are cut away to form apertures through which the oval cut-out portions of the board are discharged downwardly onto a second scrap conveyor (not shown) below the impression rolls when the die leaves such rolls.

During the feeding of the die and superposed board through the impression rolls, the board and die are held in registry by the suction from chambers 38 and 42, which acts through the apertures 8 in the die so that the individually sealed areas of the die form with the corresponding areas of the board sealed suction chambers in communication with boxes 38 and 42. By providing suction boxes both immediately upstream and downstream ofthe impression rolls 25,26, the board and die are maintained in registry throughout their travel through the rolls. By dividing the area of the die into relatively small individually sealed areas, this holding together of the die and board is enhanced, since at least some of the areas will be under suction at all times during the pass through the impression rolls. Moreover, the division of the die into small areas by extra dividers such as strip 10 supports the board more extensively and obviates the tendency of the board to cave in against the die under suction.

After leaving the upstream belt 41 of the output conveyor, the blank tends to be ejected from the die by the resilience of the rubber sealing pieces of the die, so that the blank is easily picked up by the second transfer conveyor 28. The die is then returned to the input conveyor 24to receive the next board.

It is envisaged that the ejection of the board from the die may be further enhanced by blowing air through the downstream portion of the output conveyor 27 so that pressure is applied to the board through the apertured die and thus positively blows the board off the die.

Claims (8)

1. Aflat-bed die for use in cutting and creasing a blank, the die having an operative surface provided with blades, which die is apertured for transmitting suction therethrough to the operative surface to hold a blank against the die.

2. Aflat-bed die for use in cutting and creasing a blank, which die comprises a sheet of substantially rigid material having an operative major surface provided with a pattern of projecting blades corresponding to the desired cuts and creases of the blank, in which die an area of the operative surface of the die is enclosed by a resilient sealing strip fixed to the operative surface, and at least one aperture is formed in the die within the said enclosed area so as to place the major surfaces of the die in communication.

3. A die according to claim 2, wherein the pattern of blades on the operative surface of the die includes at least one arrangement of blades extending around an area of the operative surface, the resilient sealing strip being fixed to the operative surface adjacent to the blades to enclose the said area, and an aperture being formed in the die within the said enclosed area.

4. Apparatus for cutting and creasing a blank, comprising a die according to any preceding claim, a pair of juxtaposed impression rolls defining a nip therebetween, conveying means for feeding the die and a superposed blank through the nip of the impression rolls, and suction means for applying suction through the apertured die to the operative surface of the die as the die and blank are conveyed through the impression rolls.

5. Apparatus according to claim 4, wherein the conveying means comprises a pair of parallel, spaced-apart belts travelling over a table which has a perforated portion between the two belts, the suction means comprising a suction box disposed beneath the table for applying suction to the apertured die through the perforated portion of the table.

6. Aflat-bed die substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.

7. Apparatus for cutting and creasing a blank substantially as hereinbefore described with referpence to Figures 1 to 6 of the accompanying draw ings.

8. Any novel feature or combination of features herein described.