GB2139135A - A slitting and cutting machine - Google Patents

Abstract

A cutting and slitting machine for cutting blanks from cardboard or the like having a frame (1) carrying opposed blocks (2), on each of which two sets of cutting and slitting discs (5,6) are mounted for rotation and for axial adjustment relative to one another. The blocks (2) are tiltable on the frame so that one opposed set of discs (5) can be in an operating position while the other set (6) are out of operation and can be adjusted. The discs (5,6) are supported and held in the axial positions set by locking mechanisms (11) (Fig. 5) associated with the blocks independent of the drive shafts (4) for rotating the discs for cutting. <IMAGE>

Description

SPECIFICATION A slitting and cutting machine The present invention relates to a slitting and cutting machine for cutting and slitting or scoring a strip of cardboard or similar material.

One of the final operations in the manipulation of cardboard or any similar material intended for the manufacture of packings and similar products is the cutting of the blank and the production on its surface of slits or weakened zones which function as hinges which enable the packing to be folded into the different planes in order to form an element of a certain volume and size.

The cutting of the rough strip of cardboard and the production of the said slits for the folding are carried out on a machine having a number of cutting discs facing one another, situated on parallel shafts and functioning, by contacting one another at their peripheries, as rotatory shears which cut the strip of cardboard or similar material into elements of smaller dimensions; similarly, the same machine incorporates slitting discs having a combined male and female peripheral profile; these discs, acting on the upper and lower surfaces of the strip simultaneously to produce a weakened zone which is that through which the folding of the packing is eventually effected.

In a well known embodiment of such machinery certain rigid parallel shafts are provided on which either the cutting knives or the slitting discs are mounted in some axial position by any conventional means enabling a disc, pulley or similar element to be secured to a shaft, which means in general necessitate a manual operation for positioning and subsequently tightening them. It should be borne in in mind that this positioning or securing operation for the different discs defines the precise width of the cutting and also the positions of the slits, so that the positioning of the discs is an expensive and delicate manual operation, on which the quality of the product depends, this operation consuming a considerable period of time, during which the machine is non-productive.

Since at present, apart from exceptional cases, only a small quantity is produced of any one type of blank, the positions of the different discs frequently has to be changed, the shut-off time thus being considerable and the operation of the machine thus rendered uneconomical, all this being due to the lack of flexibility in its design, which is basically intended for the production of very large quantities of each packing, the operation of changing over thus being a slow and complex one.

In addition to their limited adaptability, the machines as designed at present, with their shafts bearing the cutting and slitting discs extending from one side of the machine to the other, suffer from further drawbacks, among which attention should be drawn to the following: 1 The shafts are subjected to flexural and torsional stesses in alternation, with isolated points of concentration of tension, where the discs are secured, for which said tensions the shafts are frequently oversized, resulting in bulky and complex machines and increasing the cost of their construction and of the accessories.

2 The manual operation of positioning the discs is very imprecise, resulting in a product of inadequate accuracy, in addition to serious and uneven wear on certain essential comonents, such as the cutting discs.

These disadvantages, when added to the bulk of the machine, which requires a considerable amount of space for its erection and involves high consumption of energy, make the present machines comparatively unreliable and inexact, unnecessarily increasing the cost of producing packings and similar articles.

According to this invention the customary constructional principle of the conventional machines is altered in as much as the discs are supported by shafts imparting the rotary movement to them while all the cutting knives and also the slitting discs are now supported independently of the rotation shaft by which the movement is imparted to them, the said shaft solely performing torsion, so that other stresses, which would reduce the precision of the assembly, are eliminated; preferably the said shaft consists of a grooved element onto which the discs are fitted, being integral therewith in their rotatory movement but capable of freely sliding in the axial direction.

The machine basically consists of a frame on which is situated at least one pair of opposed blocks supporting slitting discs, each of these blocks being situated facing its counterparts higher up and lower down and having a central shaft around which it can pivot. On both sides of the said central shaft and parallel thereto are the transmission shafts which move the aforementioned cutting or slitting discs.

Each block, oscillating around its central shaft, causes a pair of shafts, with their respective discs, to operate in contact, while the other pair of shafts are separated, in an inoperative position, it being possible to position the discs on this other pair in such a way that the change-over in the production process can be effected, without loss of time, by tilting the two blocks in the reverse direction.

Each block supports the corresponding cutting discs or slitting discs via a pair of parallel plates in the manner of brackets between which are situated the supporting bearings of a disc. Through the entire set of these parallel assemblies passes the transmission shaft by which all the discs of this part of the block are driven in rotation; these cutting or slitting assemblies are not integral with the block but mounted on their respective bars, which are likewise parallel to the transmission shaftvia sliding bearings, thus enabling their axial positions to be varied, while still maintaining exact parallelism between the different discs.

Preferably the central shaft on which each block oscillates consists of a worm of which the otation, in one direction or the other, effects the axial displacement of lower assemblies fitted with rods capable of emerging under action of a pressure fluid. These rods can interact, on emerging, with a tail or extension of the assemblies bearing the discs, so that these latter can be moved in one axial direction or the other while in an inoperative position, in order to effect the exact separation required to produce the configuration of a certain type of packing.

Each cutting or slitting assmbly, bearing the appropriate disc between its plates, is fitted at the bottom with a locking piece of the nature of a lever articulated in its centre and actuated on the one hand by a spring which tends to release its other end, by means of which the assembly can be caused to assume its final axial positiion by the action of a fluid chamber by which the locking piece, via its shoe of elastomer material, is pressed onto a toothed track.

The main advantageous characteristics of the preferred embodiment described hitherto can be summarized as follows: 1 The combination of cutting knives or discs and slitting discs in paired blocks above and below the strip of cardboard or similar material, these blocks oscillating around a central shaft in such a way that one assembly is operative while the other occupies the inoperative position in which the axial spacing for a fresh production run can be prepared.

2 All the discs independently are supported by parallel supporting plates which form a cutting or slitting assembly which rests on the block.

3 Awhole series of parallel cutting and slitting assemblies have a grooved shaft passing through their discs and forming the common means imparting the rotary movement to all the discs.

4 Each cutting and slitting assembly can be displaced in the axial direction by the action of rods which, engaging for a certain particular period of time, undergo displacement together with the central worm which forms the shaft about which the block can oscillate.

5 Each cutting and slitting assembly has a locking piece by which it is secured in the exact axial position required.

To these characteristics must be added the following further important preferred features: 1 The rotation shafts, which move simultaneously by a lateral transmission of chain and pinions, can be disengaged from the rotary movement, thus reducing the energy expended and the wear suffered when the discs do not occupy the working position.

2 The knives or cutting discs, which, in pairs effect the cutting of the strip of material, when in contact, allow in at least one of the blocks and within each cutting assembly the possibility of a slight axial displacement by the action of a diaphragm into which fluid under pressure enters in opposition to elastic means, all of the foregoing being arranged in such a manner that the knives can be separated when they are not in operation, so that their cutting edges do not suffer wear, or that the contact pressure of the knives not in operation can be graduated.

With advantage a central automated control system is provided which, by digital or similar cintrol, provides unprecedented flexibility in the operation of machines of this type, thus enabling continuous work to be effected without any idle periods, even in the case of small production quantities, which can thus be manufactured at very low cost at as competitive a price as in the case of mass production.

Moreover, this new design, in addition to rendering the machine functionally flexible to a degree so far unattained, considerably improves its accuracy and operational reliability, enabling the shafts to be made lighter in weight and to operate more safely, and providing an overall assembly of lighter weight and with less inertia, thus responding more rapidly to the movements, and giving the said assembly or machine a simpler construction, so that it is naturally far less costly.

To enable the nature of the invention to be understood more clearly, the attached drawings illustrate, by way of an example and without any limitative effect, a preferred form in which it can be manufactured.

In the drawings: Figure 1 is a cross sectional elevation of a cutting and slitting machine.

Figure 2 is a detail elevation of Figure 1 showing how a slitting disc 6 is mounted on its corresponding block 2.

Figure 3 is a partial section, in profile, of the machine, showing how the different shafts of a block 2 are supported on the sides of the frame 1 of the machine, and also illustrating the elements by which the movement is imparted to the said shafts.

Figure 4 is a profile diagram, partly in section, of a pair of cutting assemblies occupying their operative position.

Figure 5 is a profile diagram, in section, of a pair of cutting assemblies occupying their non-operative position.

Figure 6 is a profile diagram, insection, of a pair of slitting assemblies, occupying their operative position.

Figure 7 is a schematic elevation of one of the sides of the machine, showing the kinematic chain which moves the spindle shafts 20.

Figure 8 is a schematic view of the invention, in profile, showing different positions of certain discs along their respective transmission shafts 4.

Figure 9 is a schematic elevation of the other side of the machine, with the kinematic chain which moves the transmission shafts 4.

The machine is essentially equipped, above and below the strip of cardboard passing through it, with disc-shaped cutting and slitting elements, positioned where required and producting from the strip the blank of a certain packing already cut up and having slits where the folding edges of the packing will be required.

The machine is formed by a frame 1 basically having two parallel vettical planes between which, as shown in Figure 1, blocks 2 are provided, each supported by a shaft 3 around which it can tilt.

As may be seen from Figure 1 each of the blocks 2 supports either a number of cutting discs 5 or a number of slitting discs 6; the former consist of a sharpened cutting knife which, interacting with an identically similar knife belonging to the opposite block 2, at the top or at the bottom, effects the shearing of the strip of cardboard, permanently deforms the latter, producing a weakened zone where the cardboard can be subsequently folded in order to form the corresponding packing.

Each block 2 has its respective transmission shafts 4 parallel to each other and to the supporting shaft 3 and forming the means of setting in rotation one or other of the sets of discs with which each block 2 is provided. The possibility of tilting each block 2 about its shaft 3 by the action of a linear actuator ensures that each such pair of blocks 2, as shown in Figure 1, will have some discs operating on the strip of cardboard, while another assembly of discs occupies its inoperative position, where it can be adjusted to give the right spaces between discs to produce the cut and slit required for a particular type of packing, without impeding the continuous cutting and slitting process being performed.

It should be noted, as a fundamental feature of this invention, that both the cutting discs 5 and the slitting discs 6 are supported directly on each block 2, even though each assembly of discs of the pair resting on this block 2 is connected in its turn to an associated transmission shaft 4 which, being a grooved component, allows of the axial displacement of all the discs situated thereon and thus of their correct positioning, so that the said transmission shaft4 only transmits a torque required forthe rotation of the assembly of discs corresponding to it.

Each disc, whether a cutting disc 5 or a slitting disc 6, is supported on the corresponding block 2 in a completely independent manner, since each disc is supported between respective side plates 7, which have an opening to give to the transmission shaft 4 and the appropriate recesses for the supporting bearings of the said disc.Each disc, whether a cutting disc5 or a slitting disc 6, with its side plates 7, thus forms a unit, as may be seen from Figure 2, which in its supporting part is provided with a pair of open bearings 8 embracing their respective parallel sliding guide bars 9, which are integral with the block 2, the entire system being so arranged that this unit or assembly, whether for the cutting or for the slitting action is able to move in the axial direction, in order to enable the strip of material to be cut to the particular width required and the different slits to be made in the required positions.

Underneath one of the sliding bars 9 is a chamber made of elastic material and filled with compressed air, acting as a cushion 10, to absorb any slight differences which may occur in the parallellism of the said sliding bars 9.

To enable each of the cutting or slitting assemblies to be held in position when operative but be adjustable when not operative a locking lever 11 is provided on each cutting or slitting assembly and consists of a single-part element pivoted in its centre between the side plates 7 corresponding to the assembly concerned.

As may be seen from Figure 2, one end of the locking lever 11 is subject to the action of a release spring 12 accommodated in a blind boring of an additional piece or tail 16 fitted in between the side plates 7; this spring 12 acts in such a way as to press a rotary element 13 onto a track which in its turn rests on a cushion 19.

The rotary element 13 is provided, at the point opposite the ball forming the rotary support, with an elastomer disc 14 capable of acting as a brake shoe when engaging the inner teeth of a supporting plate 15 of one of the sliding bars 9.

When the discs occupy their operative position the blocking cushion 19 fills with a compressed fluid which causes the lever 11 to move about its shaft, overcoming the force exerted by the spring 12 and causing the rotary element 13 and its elastomer 14to engage the toothed plate 15. This fully secures the assembly of operating discs in their final position.

When it is necessary to alter the said position it suffices to reduce the pressure prevailing in the blocking cushion 19 to enable the release spring 12 to operate, thus nullifying the braking action and enabling the cutting or slitting assemblies to be moved axially.

As may be seen from Figures 4,5 and 6, the locking lever 11 occupies, between the side plates 7 of the slitting assemblies and cutting assemblies, a position adjusted in such a way that the aforementioned requirements are fulfilled, ie that when the said lever 11 is immobilized the axial positions of each assembly along the transmission shaft 4 are firmly fixed.

However, as will be seen from the upper block 1 there is a certain gap in the axial direction between the locking lever 11 and the side plates 7 which support the said upper cutting discs.

Furthermore, as may be seen from Figure 1,the locking lever 11 in an upper cutting block 2 has a slightly different configuration, which includes an inlet or pressure fluid and also a flattened cylindrical chamber 22 which comprises a diaphragm 23 of elastic material and circular shape, while Figures 4 and 5 also show that an element is provided which is integral with the lever 11 and which accommodates in a blind boring a spring 24 of which the action causes the assembly formed by the side plates 7 and the cutting disc 5, shown in Figure 4, to assume a position in which it has been slightly displaced in the axial direction, to a sufficient extent to prevent the cutting discs 5 from remaining in contact, so that these discs 5 will not be blunted if they are not operating on the strip of cardboard.

On the other hand, if it is desired to put a pair of cutting discs 5 into operation, all that is required, as may be seen from Figure 3, is to convey pressure towards the chamber 22, where the diaphragm 23 will undergo deformation, thus overcoming the action of the spring 24 and causing an axial displacement of the upper disc, allowing the latter to come in contact with the lower cutting disc 5.

This solution also makes it possible, by graduating the pressure of the fluid acting in the chamber 22, to graduate the force with which the two cutting discs 5 make contact, so that adequate precision in the cutting of the strip of cardboard is obtained with the minimum of wear.

Up to the present we have seen how the different slitting and cutting assemblies form independent units which can remain secured in the axial position desired and also move freely within each block 2, when they are not in the operative position, in order to be adapted to the dimensions required in any particular production run. This displacement, as will be seen farther on, is carried out entirely automatic ally, also being controlled by digital control elements, so that with unprecedented rapidity and precision the cutting discs 5 and slitting discs 6 can be paired as required for the desired cardboard packing.

From Figure 2 it may be seen that each block 2 is provided in its centre with a worm 20 forming part of the supporting and tilting shaft 3 of the said block 2.

This endless spindle 20 bears one or more central carriages 17 sliding along the central part of the block 2 without being able to rotate, so that the rotation of the said worm 20 presupposes the axial displacement of the said carraige 17 in one direction or the other but always in the axial direction. In its part guided by the block 2 the carriage 17 incorporates rods 18 which normally remain in the retracted position owing to the action of a coaxial spring but which may emerge under the force of a pressure fluid, then remaining connected with a tail 16 of a projecting element which, as may be seen from Figure 2, is provided on every cutting or slitting assembly.

The rotation of the worm 20, duly enclosed in a guard 21 which protects it from dust or particles liable to reduce its precision, combined with the projecting position of a rod 18, enables the desired cutting or slitting assembly to be drawn along each block 2 by entirely automatic means with considerable accuracy and rapidity of coperation, and succes siveforward and return runs of the central carraige 17, whether or not the rod 18 projects, enable a set of cutting discs 5 or slitting discs 6 to be positioned in any way on the transmission shaft 4 within a minimum of time, the entire set of discs being transportable together, each one being left in its correct position.

Each grooved transmission shaft 4, as may be seen from Figure 8, is sufficiently long to enable all the assemblies, whether for cutting or for slitting, to be accommodated at one of its ends, when owing to the size of the packing the strip of cardboard requires no operation on its surface.

Figure 3 shows how these transmission shafts 4 are mounted on each block 2. It may be seen that within a gear box each shaft 4 or rather its extension includes plates 29 one of which, ie the outermost, is free to rotate with respect to the said shaft 4, while the other is integral therewith. Between the said plates 29 is a loose wheel 28 with a central recess where a support is provided for the entire assembly by means of bronze clutch discs 30 or the like.

The loose wheels 28 of each shaft 4 engage a pinion 27 which, via the supporting shaft 3, is integral with an external crown 26. As may be seen in Figure 9, within each cutting or slitting block 2 the crowns 26 of the shaft 3, upper and lower, are engaged, the said crowns 26 being connected by means of a chain, belt or similar transmission between the cutting and slitting blocks and with an electric motor which sets the entire assembly in motion.The rotation of this motor, via the transmission described, and with the directions shown in Figure 8, causes the constant rotation of the loose wheels 28, but this rotation is only transmitted to the actual transmission shaft 4 when pressure is exerted through an inlet 32 on a piston 31 which pressure causes it to thrust one of the plates 29, whereby the entire set of plates 29, clutch discs 30 and loose wheel 28 is rendered integral, thus causing the rotation of the corresponding transmission shaft 4.

As maybe seen from Figure 6, the endless spindle (worm) 20 occupies a central position, coaxially with the supporting shafts 3, being integral with one of the said shafts, on which the block 2 is mounted via the corresponding bearings which enable it to tilt and also enable each supporting shaft 3 to rotate freely. The worm 20 with the shaft 3 integral therewith forms an assembly to which a toothed crown wheel 25 is affixed outside the frame 1.

The crown 25, as may be seen from Figure 7, engages its corresponding component on the upper block, and between the cutting and slitting blocks a transmission is established by means of a chain or similar device, which in turn is provided between one of the worms and a lower electric motor, which is the element which simultaneously rotates all the worms 20, and with the combination of the draw rods 18, ensures the correct positioning of each cutting or slitting assembly, in all cases with simultaneity as between the worms 20 of one and the same block.

Claims (15)

1. A slitting and cutting machine for a strip of cardboard for similar material, of the type using pairs of upper and lower discsfor cutting or slitting the strip, comprising a frame with a number of pairs of blocks on opposite sides of the plane of movement of the strip, each of the blocks having two transmission shafts for driving the discs and a parallel central shaft, each block being capable of tilting in relation to its central shaft, simultaneously with the tilting of the other block of its pair, this tilting movement causing the disc supporting shafts of each pair of upper and lower discs to move closer together or farther apart, so that at least one pair of shafts remains operative for cutting or slitting and at least one other pair is positioned in reserve, in which position the gaps between the planes of action of the discs can be varied, each block being subject to the principle of separation by which the transmission shafts only perform the precision functions; ie those of operating and guiding in the change of the working plane, while the remaining functions, which are those of the retention of each disc in its working plane, are effected, through its means of adjustment and retention, by the structure of the block itself, which is integral with the frame of the machine, except as regards its tilting capability.

2. A slitting and cutting machine in accordance with claim 1 in which each disc supporting shaft incorporates the discs fixed radially relative thereto so that they are rotationally integral therewith but allowing of their displacement along the shaft, each disc being centred between a respective two side plates, means being provided to immobilize or secure the said discs in the position selected, while allowing axial repositioning when required.

3. A slitting and cutting machine according to claim 2 in which the means for immobilizing each disc consist of a locking lever mounted between the side plates of each disc and mov-ing together with these latter; this locking lever including a head bearing an elastomer material via which it interacts with a toothed track under the action of a removable thrust means.

4. A slitting and cutting machine according to claim 3 in which the thrust means by which the head of the locking lever is thrust against the toothed track includes a fluid conduit, pressure within which effects the thrust, the actual head of the locking lever including a rounded surface element serving to make the contact with the fluid conduit, while the tail of the locking lever, or the zone opposite to that of its head, is subjected to the action of elastic means which urge the locking lever to an unlocking position against the action of the thrust means.

5. A slitting and cutting machine according to any of the preceeding claims including as a means of selectively displacing each disc in one direction or the other a retractable element arranged to make contact with a tail of each cutting or slitting disc assembly, thus conveying the said tail, together with the said cutting or slitting assembly, to the position selected in each case.

6. A slitting and cutting machine according to claim 5 in which the retractable element which acts on the tail of each cutting or slitting assembly consists of part of a piston and cylinder assembly, its selective displacements being effected by means of a spindle or threaded shaft, provided on a central shaft paraxial with the pair of disc supporting shafts of each block.

7. A slitting and cutting machine according to claim 6 in which the movements and operation of the retractable element exerting a thrust on the tail of each cutting or slitting assembly are mechanized, thus enabling such factors as the number of discs to be displaced in each case, and the distance by which they are to be displaced, to be automated.

8. A slitting and cutting machine according to any of the preceeding claims including means arranged to enable the degree of pressure between each corresponding pair of cutting discs to be regulated selectively and independently, this pressure thus being controlled when it is necessary or suitable as is the case with discs which are out of operation during a certain phase of work, blunted discs, or similar circumstances.

9. A slitting and cutting machine according to claim 8 together with claim 2 in which the means for regulating the pressure between opposed cutting discs consists of a member which is preferably the locking lever itself, which is mounted in such a way as to leave a certain gap between the side plates of the disc, while elastic means are provided for operation in the opposite direction in respct of the said member the action of at least one of these latter means being adjustable, thereby enabling the side plates and consequently their disc to be displaced in one direction, this displacement being a function of the regulated action of the elastic means, resulting in the possibility of independently controlling the pressure between cutting discs, which pressure can be reduced or even selectively nullified in one or more pairs of discs when required, while the remainder continue normally at their working pressure.

10. A slitting and cutting machine according to claim 9 in which the locking lever itself defines a conduit for the entry of fluid under pressure into a chamber provided with an elastic diaphragm designed to exert a thrust against one of the side plates themselves, thus constituting one of the aforementioned elastic means for regulating the pressure between discs, the other elastic means consisting of a spring.

11. A slitting and cutting machine according to claim 2 or any claim dependent thereon in which the side plates of each disc are connected with their respective guide bars via open bearings which keep them correctly aligned at all times.

12. Aslitting and cutting machine according to any of the preceeding claims including motor means arranged to set up the rotation of a gearing coupled to another two in coplanar alignment, these latter being mounted on the pair of transmission shafts of each block, with which shafts they can be rendered rotationally integral by the action of respective clutches, the operative transmission shaft thus being caused to rotate and the reserve shaft to remain stationary.

13. A slitting and cutting machine according to any ofthe preceeding claims in which the longitudinal dimension of each transmission shafts is greater than the width oftheworking strip, in order to define, at least at one end of each shaft, a zone serving to store a reserve of cutting or slitting discs.

14. A slitting and cutting machine according to any of the preceeding claims including a piston and cylinder assembly for each block to enable it to be tilted in relation to the frame of the machine.

15. A slitting and cutting machine substantially as described herein with reference to, or as illustrated in the accompanying drawings.