EP2655022B1

EP2655022B1 - Device for cutting a flat element

Info

Publication number: EP2655022B1
Application number: EP11813418.8A
Authority: EP
Inventors: Massimiliano SALE
Original assignee: Manz Italy SRL
Current assignee: Manz Italy SRL
Priority date: 2010-12-24
Filing date: 2011-12-21
Publication date: 2019-02-13
Anticipated expiration: 2031-12-21
Also published as: WO2012085866A2; WO2012085866A3; EP2655022A2

Description

Background of the invention

The invention relates to a cutting device, in particular for cutting flat elements, for example in the form of a sheet or strip.
Specifically, but not exclusively, the invention can be used for cutting flat elements in the form of a sheet or strip, for example approximately 20 micrometres to 200 micrometres thick, made, for example, of composite, metal, plastic, paper or ceramic material. The invention can be suitable for cutting a continuous flat element transported along an advancing path to separate the continuous flat element into various distinct portions.
In particular, reference is made to a cutting device for cutting a flat element, that advances in an advancing direction, with a cut that is transverse to the advancing direction. The cutting device according to the invention can particularly comprise two blades that cooperate together, superimposing the cutting edges thereof, to perform a succession of transverse cuts on the flat element, which is continuous and extends in length in the advancing direction, to divide the flat element into various distinct portions.
Such a cutting device is known in which the cutting edges of the blades are tilted in relation to one another to thus form a cutting angle defined by the parallel projections of the cutting edges onto a plane that is normal to the direction of the length of the flat element to be cut; the blades operate with a cutting mode of the scissor type, according to which the current cutting zone, which consists of the crossing point of the cutting edges, advances from one side to another of the width of the flat element to be cut. It is further known that in order to improve the effectiveness of the cut, both the cutting edges, or at least one thereof, can have a curved profile, even when it is desired to cut along a rectilinear cutting line.
In the context of this description, "parallel projections" are intended the parallel projections (orthogonal or oblique) of the descriptive geometry.
It is further known that, in order to improve cutting efficiency, the blades can be configured in such a manner that the cutting edges are tilted in relation to one another to form an angle, said cross angle, defined by the parallel projections of the cutting edges onto a plane (projection plane) parallel to the lying plane of the flat element to be cut.
Various aspects of known cutting devices are improvable.
Firstly, it is desirable to reduce wear to the cutting edges. In particular, wear is normally concentrated in certain zones of the cutting edge compared with other zones, so the most worn zones rapidly lose cutting efficacy, with the consequent need to replace the blade relatively soon.
Secondly, it is desirable to maintain substantially constant cutting quality along the entire extent of the cutting zone, in particular over the entire width of the flat element being cut.
Another improvable aspect is to be able to maintain cutting pressure as regular and/or uniform as possible during cutting from one side to the other of the width of the flat element. It is further desirable, more in general, that the various features of the cut, such as, for example, the size of the cross angle, are maintained regular and/or uniform during cutting.
Document US4476760A discloses a device as in the preamble of claim 1. Each of documents DE102008044465B3 and GB1066536A discloses a device for cutting a flat element which is continuously moving.

Summary of the invention

One object of the invention is to provide a cutting device that is able to improve the known technique for one or more of the aspects indicated above.
One advantage is to provide a cutting device that is suitable for cutting transversely a flat element, which advances along an advancing path, to divide this element into distinct portions.
One advantage is to reduce wear of the cutting edges, consequently increasing the working life of the cutting device without having to replace the blades.
One advantage is to make available a cutting device in which the entire lengths of the cutting edges are worn in a substantially uniform manner.
One advantage is to devise a cutting device that is able to provide a rectilinear cut of great precision on a flat element.
One advantage is to cut a continuous flat element into in distinct portions by means of a series of cuts, each performed from one side to the other of the width of the elements, with relatively high productivity.
One advantage is to give rise to a constructionally simple and cheap cutting device, of the type in which the cutting edges of the blades are tilted with respect to one another, forming a cutting angle, defined by the parallel projections of the cutting edges onto a plane (projection plane) that is normal to the length of the flat element to be cut, and a cross angle, defined by the parallel projections of the cutting edges on the flat element to be cut (projection plane), and in which the blades operate in scissors cutting mode, such that the current cutting zone advances from a side of the flat element to be cut to the opposite side.
One advantage is to permit substantially constant cutting quality along the entire extent of the cutting zone, in particular for the cutting line extending along the entire width of the flat element.
One advantage is to maintain the cutting pressure as uniform and regulate as possible during the course of cutting from one side to the other of the width of the flat element.
One advantage is to maintain constant the width of the cross angle during cutting.
Such objects and advantages, and still others, are reached by the cutting device of one or more of the claims set out below.

Brief description of the drawings

The invention can be better understood and implemented with reference to the attached drawings that disclose embodiments thereof by way of non-limiting examples.

Figure 1 is a perspective view of an illustrative example of a cutting device not according to the invention.
Figure 2 is a view of the device in figure 1 according to another perspective.
Figure 3 is the view of figure 1 with some parts removed to highlight others better.
Figure 4 is a lateral view in a vertical elevation of the device in figure 1.
Figure 5 is a side view of the left side of figure 4.
Figure 6 is a top plan view from the upper side of figure 4.
Figure 7 is section VII-VII of figure 4.
Figure 8 is a fragmentary section VIII-VIII of figure 4.
Figure 9 is a section IX-IX of figure 4.
Figure 10 is an enlargement of a detail of figure 3.
Figure 11 is the view of figure 4 with some parts removed to highlight others better.
Figure 12 is an enlarged detail of figure 7.
Figure 13 is a perspective view of the device of the preceding figures, with some parts removed to highlight better the side of the cam member 19 that has the fifth cam profile 29.
Figure 14 is a view in another perspective, with some parts removed to highlight better the side of the cam member 19 having the first cam profile 21.
Figure 15 is a perspective view of a cutting device according to the invention, with some parts removed to highlight better the tilted path of the first carriage 7.
Figure 16 is the device in figure 15 seen according to another perspective.
Figure 17 is a raised vertical view of a detail of the device in figure 15.
Figure 18 is a view from the side opposite figure 17.

Detailed description

With reference to the aforesaid figures, with 1 overall a cutting device has been indicated for transverse cutting of a continuous flat element, for example in the form of a strip. The cutting device 1 is in particular used for cutting a front end portion and separating it from the rest of the continuous element. The cutting device 1 can, in particular, perform a series of transverse cuts to cut, one after the other, various front end portions of the continuous flat element. The cutting device 1 operates, in particular, to perform, each time, a straight cut.
The cutting device 1 can be used to cut sheet or strip elements, which are, for example, approximately 20 micrometres to approximately 200 micrometres. In particular, the flat element to be cut can be made of composite, metal, plastic, paper or ceramic material, or of still other materials.
The cutting device 1 comprises two blades that cooperate together to cut the flat element by superimposing the cutting edges thereof. The two blades are a first blade 2, that in the specific case is an upper blade, and a second blade 3, which in the specific case is a lower blade. The cutting motion may comprise the motion of either of the two blades, or of both the blades. In the specific case, the cutting motion comprises the motion of a single blade that may be, as in this case, the first (upper) blade 2. During cutting, the other blade, which in this case will thus be the second (lower) blade 3, can be stationary with respect to the element to be cut during cutting, in particular for defining with precision a straight cutting line. The other blade, in this case the second (lower) blade 3, can be provided, as in the specific example, with the possibility of motion away from or towards the blade (first blade 2) provided with the cutting motion to enable, before cutting, entry of the flat element to be cut that advances between the two blades.
Blades 2 and 3 have respectively cutting edges 4 and 5 that are tilted in relation to one another so as to form a cutting angle, considering the parallel projections of the cutting edges 4 and 5 onto a plane (projection plane, in this case vertical) that is normal to the direction (in this case horizontal) of the length of the flat element to be cut and/or to the advancing direction 6 of the element. Figure 5, which lies on the (vertical) plane on which the cutting angle is arranged, makes the reciprocal tilt of the two cutting edges 4 and 5 visible. In the specific case, the second lower cutting edge 5, (which is stationary during cutting with respect to the element to be cut) is arranged horizontally, whilst the first upper cutting edge 4, (which is the specific case is movable vertically with respect to the element to be cut, to generate the cutting motion) is arranged obliquely. The two blades 2 and 3 operate in a cutting mode of the scissors type in which the cutting zone comprises the cross point of the cutting edges 4 and 5, cross point which advances from one side to the opposite side of the element to be cut. In particular, the cross point, or cutting zone, advances from one side to the other of the width of the flat element to be cut by separating a portion from the element.
The two blades 2 and 3 are further configured in such a manner that the cutting edges 4 and 5 thereof are tilted in relation to one another in such a manner as to form a cross angle, defined by considering the parallel projections of the cutting edges 4 and 5 onto a plane (projection plane, in the specific case, horizontal) that is parallel to the lying plane of the flat element to be cut. This cross angle, which, as known, improves the efficacy of the scissors type cut, can be, for example, comprised between approximately 0.05 and 3 sexagesimal degrees, or comprised between approximately 0.1 and 0.5 sexagesimal degrees.
At least one of, or both the cutting edges 4 and 5, can have a curved or rectilinear profile. In the specific case, both the first (upper) cutting edge 4 and the second (lower) cutting edge 5 are rectilinear.
The first blade 2 is carried by a first movable carriage 7 (which is in particular slidable on linear sliding guides) in the direction (vertical or tilted with a vertical motion component) of the cutting motion, in both directions. The second blade 3 is carried by a second carriage 8 that is movable (in particular slidable on linear sliding guides) in the (vertical) direction of moving away from and towards the first blade 2, to enable reciprocal moving away of the blades before cutting in order to facility the entry of the flat element to be cut that advances between the two blades and thus to promote correct positioning of the flat element above the second (lower) blade 3.
The first carriage 7 and the second carriage 8 are in turn carried by a main carriage 9 on which the (linear) sliding guides are mounted with which the first and the second carriage are slidably coupled. The main carriage 9 is movable (for example linearly slidable) with reciprocal movement in the advancing direction 6 (horizontal) of the flat element to be cut.
The cutting device 1 further comprises one or more gripping members 10 (in the specific case three), for example of the pinch type. Each gripping member 10 is arranged after blades 2 and 3 (with reference to the advancing direction 6 of the element to be cut) to grip the flat element during cutting. The gripping member 10 will be, in particular, arranged alongside one another in the direction of the width of the element to be cut. Each gripping member 10 is configured for gripping the flat element portion that exceeds the blades 2 and 3 and is separated from the rest of the flat element by the blades.
Each gripping member 10 may comprise a first (upper) jaw 11 and a second (lower) jaw 11. Each gripping member 10 is provided with at least one elastic element 13 (spring) applied to at least one jaw 11 or 12 to enable an elastic action of gripping the element. Each first (upper) jaw 11 is carried by the first carriage 7, i.e. by the carriage that carries the first (upper) blade 2. Each (lower) second jaw 11 is carried by the second carriage 8, i.e. by the carriage that carries the second (lower) blade 3. In particular, the elastic element 13 will be operative on the first jaw 11, i.e. on the jaw associated with the first carriage 7 (that carries the first blade 2) that provides the cutting motion. The (vertical) motion of the first carriage 7, that supplies the cutting motion to the first blade 2, will also supply the gripping motion to each first jaw 11 to enable the jaws of each gripping member 10 to be closed reciprocally.
The first blade 2 is fitted to the first carriage 7 with the possibility of performing rotations (of relatively reduced extent) around a pivot or fulcrum 14 with a rotation axis that is substantially perpendicular to the advancing plane or to the lying plane of the flat element to be cut. In the specific case this rotation is vertical.
The cutting device 1 comprises an adjusting carriage 15 configured for exerting a force on the first blade 2. In particular, the adjusting carriage 15 is configured for generating a rotation moment on the first blade 2 with respect to the aforesaid rotation pivot or fulcrum 14. In particular, the adjusting carriage 15 is configured for pushing the first blade 2 against the second blade 3 during the cutting action in which the corresponding cutting edges 4 and 5 are at least partially superimposed on one another. The adjusting carriage 15 is in particular used to maintain the first blade 2 in contact with the second blade 3 in the cutting operating situation, with the cutting edges 4 and 5 superimposed, with a contrasting force or pressure (with a direction that is transverse to the cutting plane/surface along which the first cutting edge 4 is movable) of preset size. This contrasting force or pressure (such as to maintain the cutting edges 4 and 5 in reciprocal contact) can be adjusted during the performance of each single cut, as will be explained better below, in such a manner as to make the cut particularly effective, precise and uniform.
The adjusting carriage 15 is, in this example, carried by the main carriage 9 (in other non-illustrated examples it could be carried by the first carriage 7) with the possibility of movement (for example linear sliding) in a (horizontal) adjusting direction 16 that is transverse to the rotation axis of the first blade 2. The adjusting carriage 15 is movable in the adjusting direction 16 in both directions. The adjusting direction 16 may be, in particular, parallel to the advancing plane or to the lying plane of the flat element to be cut, and/or parallel to the advancing direction 6. The adjusting carriage 15 is configured in such a manner as to exert a force on the first blade 2 that is able to give rise to a rotation moment applied to the first blade 2 according to at least a first rotation direction. In particular, the adjusting carriage 15 may be, for example, connected to the first blade 2 in such a manner that the carriage 15, by moving in a first direction 16a of the adjusting direction 16, generates a rotation moment for rotating the first blade 2 in the first rotation direction, such that the first blade 2 contrasts the second blade 3 with a desired contrasting force or pressure. The adjusting carriage 15 can move in a second direction of the adjusting direction 16, opposite the first, to enable the first blade 2 to release or decrease the contrasting force or pressure on the second blade 3, by rotating in a second rotation direction opposite the first rotation direction 16a.
The adjusting carriage 15 will be driven in such a manner that the contrasting force or pressure between the first blade 2 and the second blade 3 (in the course of the cutting step in which the cutting edges 4 and 5 of the two blades 2 and 3 are superimposed) follows a desired course (for example remains almost constant) in the course of each single cut. In other words, during cutting, whilst the cross point of the cutting edges 4 and 5, or cutting point (i.e. the point in which cutting of the flat element occurs instantaneously and which substantially forms the instantaneous vertex of the cross angle), moves laterally in the direction of the width of the flat element from one side to the other of the latter, the adjusting carriage 15 is guided in such a manner as to exert a given thrust force on the first blade 2 in order that the contrasting force or pressure between blades 2 and 3 is, instant by instant, the desired one. In the specific case, the adjusting carriage 15 is guided in such a manner as to increase gradually the thrust force on the first blade 2 so that the contrasting force or pressure between blades 2 and 3 is constant during performance of cutting for the entire cutting line, i.e. over the entire width of the cut element. In particular, the adjusting carriage 15 will be moved (as will be explained better below in the present description) according to a preset motion law in such a manner as to obtain the desired variation in the thrust force on the first blade 2.
The reciprocating movement (backwards and forwards) of the main carriage 9 is guided by a cam guiding system that comprises a motor shaft 17 rotated by a motor 18 (for example of the brushless type), at least one cam member 19 rotated by the motor shaft 17 and at least a first cam follower member 20 connected to the main carriage 9. The cam member 19 (driving member) can have at least a first cam profile 21, for example of the track type. The first cam follower member 20 (driven member) of the main carriage 9 may comprise, as in the specific example, a first roller coupled with the first cam profile 21. The cam guiding system may be configured in such a manner that a cycle of the reciprocating movement of the main carriage 9 (i.e. a forward and return stroke) corresponds to each revolution of the motor shaft 17.
The cutting motion of the first carriage 7 (reciprocating motion with opening and closing stroke) may be guided by the aforesaid cam guiding system. The reciprocating opening and closing motion of the second carriage 8 (to move from the upper or closed cutting configuration of the second blade 3 to the lower or open configuration ready for the entry of the element to be cut) may be guided by the aforesaid cam guiding system. The cam member 19 (driving member) may have, as in the specific example, a second cam profile 22 coupled with a second cam-follower member 23 (driven member) connected to the first carriage 7 and to the second carriage 8. The second cam-follower member 23, which is thus operationally associated with both the first 7 and second 8 carriages, may comprise a second roller coupled with the second cam profile 22. In the specific case, the second cam-follower member 23 is carried by a further cam member 24 that is commanded (through the effect of the coupling between the second cam-follower member 23 and the second cam profile 22) to perform a set oscillating motion. The further cam member 24 may comprise, as in the specific case, a plate body (that is, for example, rectangular in shape). The further cam member 24 has a third cam profile 25 (for example of the track type), operationally associated with the first carriage 7, and a fourth cam profile 26 (for example of the track type), operationally associated with the second carriage 8. The first carriage 7 carries a third cam-follower member 27 coupled with the third cam profile 25 such that the reciprocating movement of the first carriage 7, which supplies the cutting motion to the first (upper) blade 2 and the gripping motion of the first (upper) jaws 11, is driven by the oscillation motion of the further cam member 24. The third cam-follower member 27 may comprise, for example, a roller coupled with a corresponding track cam. The second carriage 8 carries a fourth cam-follower member 28 coupled with the fourth cam profile 26 in such a manner that the reciprocating movement of the second carriage 8, which supplies opening and closing motion to the second (lower) blade 3 and to the second (lower) jaws 12, is guided by the oscillating motion of the further cam member 24. The fourth cam-follower member 28 may comprise, for example, a roller coupled with a corresponding track cam. The motion of the blades 2 and 3 and of the jaws 11 and 12 is thus guided (by means of the third cam profile 25 and the fourth cam profile 26) by the motion of the further cam member 24, which is in turn guided (by means of the second cam profile 22) by the motion of the cam member 19.
The cam member 19 has a fifth cam profile 29 operationally associated with the adjusting carriage 15 to command the movements of the carriage, such as to vary the force exerted by the carriage on the first blade 2 (generating a rotation moment applied to the first blade 2 around the rotation pivot or fulcrum 14). The adjusting carriage 15 carries a fifth cam-follower member 30 coupled with the fifth cam profile 29 such that the motion of the adjusting carriage 15, which generates the rotation moment applied to the first blade 2 to enable the contrasting force or pressure between blades 2 and 3 to be varied, is guided by the rotary motion of the cam member 19.
The fifth cam profile 29 may be shaped in such a manner that the thrust of the adjusting carriage 15 on the first blade 2 is varied, from the start to the end of the actual cutting step, such that the contrasting force or pressure between blades 2 and 3 remains substantially constant.
In the specific example, the adjusting carriage 15 has a bridge element 31 configured for transmitting the force from the adjusting carriage 15 to a blade-holding arm 32 that holds the first blade 2. The bridge element 31 is connected to the blade-holding arm 32 by means of elastic means that may comprise, as in this case, one or more belleville washers 33 (with relatively great stiffness). Using one or more belleville washers 33 enables a very stiff elastic connection to be provided that can reduce the risk of system resonance.
In the specific case, there are thus three cam profiles (the first 21, the second 22 and the fifth 29) that drive three movable elements (respectively, the first carriage 7, the second carriage 8 and the adjusting carriage 15) and which are carried by a single rotating organ (the cam member 19). It is possible to provide other embodiments in which the aforesaid three cam profiles 21, 22 and 29 are carried by two or three distinct rotating members (of the cam type) that may be driven by a single motor.
The cutting device 1 may be combined with a supplying device (of known and not illustrated type) that conveys, with a continuous advancing motion, the flat element to be cut to supply the latter to the work unit formed by the blades 2 and 3 and by the gripping member 10. The cutting device 1 may be further combined with an evacuating device (of known and not illustrated type) that removes from the cutting device 1 the cut portions of material separated from the flat element.
The first carriage 7 is movable on the main carriage 9 in a movement direction that can be tilted (as in the embodiment of figures 15 to 18) with a preset angle of tilt with respect to the second cutting edge 5 and/or with respect to the lying plane of the flat element to be cut. In particular, this angle of tilt can be formed by the movement direction of the first carriage 7 and by a line that is normal to the lying plane of the flat element to be cut and can have a value comprises between 1 and 20 sexagesimal degrees, or more specifically between 2 and 12 sexagesimal degrees, for example about 8 - 9 degrees.
The first carriage 7 in the case in point is slidable on linear guides with a sliding axis that is tilted according to the aforesaid angle of tilt. This angle of tilt is chosen in such a manner that the cross angle between the edges 4 and 5 remains substantially constant at a desired value. It has in fact been seen that by tilting the movement direction of the first blade 2 with respect to the flat element to be cut, the cross angle can be maintained almost constant from the start to the end of the cutting step, i.e. for the entire length of the cutting line. In other words, in the example in figures 15 to 18, the direction of the cutting motion (in this case the cutting motion is supplied by the motion of the first blade 2) is tilted with respect to the second cutting edge 5 and/or with respect to the lying plane of the flat element to be cut, i.e. is not perpendicular to the edge 5 and/or to the flat element. In particular, the direction of the cutting motion will be tilted forwards with respect to the fixed cutting edge, such that the fulcrum 14 of the movable blade during cutting (whilst the cutting edges become gradually more superimposed) has a motion component directed to the outside of the cutting line, always maintaining an operative contact point of the cutting edges in which cutting occurs, a contact point that advances gradually from one side to the other of the width of the flat element. The (horizontal) motion component, in particular, directed to the outside of the movable blade, and in particular of the fulcrum 14 of the blade, will ensure that the cross angle remains constant.
As has been seen, the embodiment of figures 15 to 18 differs from that of figures 1 to 14 essentially through the fact that the carriage that supplies the cutting motion (first carriage 7) is movable (with reciprocating movement) in a cutting direction that is not only transverse to the flat element, but is also tilted with respect to a plane that is orthogonal to the flat element, in order to maintain constant the cross angle during cutting of the flat element. This cutting direction is tilted in such a manner that, during cutting, in the transition from the open to the closed configuration, there is at least one component of the motion of the first carriage 7 that is directed in the advancing direction 6. Also in this second embodiment, the cutting motion may comprise a linear sliding motion. This tilted cutting motion of a blade (first blade 2) may comprise, in an embodiment that is not shown, a route that is at least partially non-linear (curvilinear), in particular, if one or both the cutting edges are not rectilinear.
If the motion of the first carriage 7 is tilted, the jaw/s 11 carried by the first carriage 7 can be provided with motion with a tilted direction and can be further mounted elastically to avoid dragging on the flat element.
In use, for both the disclosed examples, whilst the flat element to be cut is supplied with continuous motion (for example at constant speed) in the advancing direction 6, the motor shaft 17 rotates the cam member 19. The main carriage 9 is thus guided in reciprocating backward and forward movement in a direction that is parallel to the advancing direction 6 and in a manner that is coordinated with the advance of the element to be cut. At the same time, the oscillating movement of the further cam member 24 is guided in such a manner as to guide, in turn, via the third cam profile 25 and the fourth cam profile 26, the reciprocating movement of the first carriage 7 and the reciprocating movement of the second carriage 8. The first carriage 7, like the second carriage 8, are thus moved both in the (horizontal) advancing direction of the element to be cut (both being mounted on the main carriage 9), and in the (vertical or tilted) opening and closing direction (being guided by the cam guiding system), in such a manner that the flat element is cut as it advances continuously. The cut is made during the forward stroke of the main carriage 9.
Blades 2 and 3 take on at least one closed configuration, in which the cutting edges 4 and 5 are superimposed on one another to perform the cut, and at least one open configuration, in which the cutting edges 4 and 5 are spaced apart from one another in the cutting direction, defining a passing opening 34 that enables the (continuously advancing) flat element to be cut to enter between the cutting edges 4 and 5. The passage opening 34 is narrowed and elongated in the direction of the width of the flat element to be cut, i.e. in a direction that is transverse to the cutting direction and to the advancing direction 6. Blades 2 and 3 move from the open to the closed configuration in such a manner that the point or cutting zone, defined by the cross point of the cutting edges 4 and 5, moves along the cutting line from one side to the other of the flat element.
The relative movement between the cutting members (the two blades 2 and 3) and the element to be cut is thus substantially reduced during cutting only to the (vertical) cutting motion and to the possible adjusting motion of the cross angle (i.e. the tilted motion of the first blade 2). The relative movement between the cutting members (the two blades 2 and 3) and the element to be cut in the advancing direction 6, whilst the cut is being made, is substantially nil (apart from the possible motion component due to the tilt of the motion of the first blade 2), inasmuch the cutting members are moved forwards in a manner coordinated with the advance of the flat element. In the same manner, the gripping members 10 grip the front end of the flat element that advances during the forward stroke of the main carriage 9. Whilst the flat element is held by the gripping members 10, the latter are moved forwards in such a manner as not to have a dragging motion with respect to the gripped element.
During cutting, the fifth cam profile 29 guides the adjusting carriage 15 according to a preset law in such a manner as to control the rotation moment applied to the first blade 2 as the cross point (or cutting point) advances from one side to another of the width of the flat element. As said, this is achieved by movement (controlled by the fifth cam profile 29) of the adjusting carriage 15 that causes slight rotations of the first blade 2 (or of the blade-holding arm 32) around the rotation pivot or fulcrum 14. This movement is controlled in such a manner that the front contrasting force between the blades 2 and 3 is constant along the entire cutting line, so that the cutting quality will be uniform.
The cross angle between the edges 4 and 5 (in particular, the cross angle will have, instantaneously, the vertex in the cross point of the cutting edges 4 and 5 and will be formed by the parallel projections of the cutting edges 4 and 5 onto a plane (projection plane) that is parallel to the lying plane, or advancing plane, of the flat element to be cut) will be further maintained substantially constant form the start to the end of the cutting step by the effect of the tilt of the cutting motion. It has been seen that the constancy of the cross angle contributes to obtaining a cut of uniform quality on the entire cutting line. Thus, during cutting, whilst the cross point of the cutting edges 4 and 5, or cutting point (i.e. the point in which cutting of the flat element is occurring instantaneously and which substantially forms the instantaneous vertex of the cross angle) moves laterally in the direction of the width of the flat element from one side to the other of the latter, the first blade 2, whilst it is lowered, performs a tilted movement with respect to the vertical so that the cross angle remains almost constant substantially for the entire side movement of the cross point.
Once the cut has been made, the blades 2, 3 and the jaws 11, 12 open, for example just before the end of the forward stroke of the main carriage 9, then the blades 2, 3 and the jaws 11, 12 perform the return stroke to the open position, then resume the subsequent forward stroke to cut a new portion of the flat element that, in the meantime, has continued to advance.
The cutting device 1 may comprise, as in the illustrated examples, a clearance recovery carriage 35 that is slidable (for example on linear guides) on the adjusting carriage 15 and is maintained pressed against the blade-holding arm 32 by the elastic means (belleville washers 33). The bridge element 31 may, as in this case, bridge the clearance recovery carriage 35.

Legend

1: Cutting device
2: First blade
3: Second blade
4: First cutting edge
5: Second cutting edge
6: Advancing direction
7: First carriage
8: Second carriage
9: Main carriage
10: Gripping members
11: First jaws
12: Second jaws
13: Elastic element
14: Pivot or fulcrum
15: Adjusting carriage
16: Adjusting direction
16a: First direction of the adjusting direction
17: Motor shaft
18: Motor
19: Cam member
20: First cam follower member for the main carriage 9
21: First cam profile for the main carriage 9
22: Second cam profile for the further cam member 24 and for the carriages 7 and 8
23: Second cam-follower member for the further cam member 24 and for the carriages 7 and 8
24: Further cam member
25: Third cam profile for the first carriage 7
26: Fourth cam profile for the second carriage 8
27: Third cam-follower member for the first carriage 7
28: Fourth cam-follower member for the second carriage 8
29: Fifth cam profile for the adjusting carriage 15
30: Fifth cam-follower member for the adjusting carriage 15
31: Bridge element
32: Blade-holding arm
33: Belleville washers
34: Passage opening
35: Clearance recovery carriage

Claims

Device for cutting a flat element, which advances in an advancing direction (6), with a cutting line that is transverse to the advancing direction (6), said cutting device (1) comprising:
- a first blade (2) and a second blade (3) having, respectively, a first cutting edge (4) and a second cutting edge (5) extending in length transversely to the advancing direction (6), said first and second blades (2; 3) cooperating together to cut the flat element with the possibility of taking on an open configuration, in which said first and second cutting edges (4; 5) are spaced apart from one another, defining a passage opening (34) to insert the flat element to be cut, and a closed cutting configuration, in which said first and second cutting edges (4; 5) are superimposed on one another; said first and second blades (2; 3) being configured so as to define a cutting zone that comprises a crossing point between said first and second cutting edges (4; 5) which, during cutting, in the transition from the open to the closed configuration, moves from one side of the flat element to the opposite side;

- moving means (7; 8; 9) to supply a cutting motion to said first blade (2) and/or to said second blade (3) for the transition between said open and closed configurations, said moving means comprising a first carriage (7) that carries said first blade (2) and is movable with reciprocating movement in a cutting direction that is transverse to the flat element;
characterized in that said cutting direction is tilted with respect to a plane that is orthogonal to the flat element.
Device according to claim 1, wherein said first and second blades (2; 3) are configured such as to define, during cutting, a cross angle, said cross angle being defined by parallel projections of said first and second cutting edges (4; 5) on a projection plane defined by the flat element to be cut, said cutting direction being tilted in such a manner as to maintain said cross angle constant during cutting of the flat element.
Device according to claim 1 or 2, wherein said cutting direction is tilted in such a manner that, during cutting, in the transition from the open configuration to the closed configuration, there is at least one motion component of said first carriage (7) which is directed in said advancing direction (6).
Device according to any one of the preceding claims, wherein said cutting motion comprises a linear motion.
Device according to claim 4, comprising a main carriage (9) that slidably carries said first carriage (7), said main carriage (9) being movable with a reciprocating motion in the advancing direction (6) with a forward stroke and a backward stroke in a manner that is coordinated with the advance of the flat element to be cut, whereby said first blade (2) and second blade (3) take on the closed configuration in at least a part of the forward stroke and the open configuration in the backward stroke.
Device according to any preceding claim, comprising thrust means (15) for exerting a thrust on said first blade (2) and/or on said second blade (3) such as to maintain, during cutting, said first and second cutting edges (4; 5) against one another with an opposing force.
Device according to claim 6, comprising controlling means (17; 19; 29; 30) configured for controlling said thrust means (15) so as to vary the entity of said thrust during cutting.
Device according to claim 7, wherein said first blade (2) is pivoted on said first carriage (7) by a pivot or fulcrum (14) around a rotation axis, said thrust means comprising an adjusting carriage (15) that is movable in an adjusting direction (16) and configured in such a manner that said thrust generates on said first blade (2) a rotation moment with respect to said rotation axis, said controlling means being configured for controlling movements of said adjusting carriage (15).
Device according to claim 7, wherein said first and second blades (2; 3) are configured for performing a reciprocal rotation around a rotation axis that is transverse to the advancing direction (6) and to said first and second cutting edges (4; 5), said thrust means being configured in such a manner that said thrust generates on said first blade (2) and/or on said second blade (3) a rotation moment with respect to said rotation axis; said first and second blades (2; 3) being configured such as to define, during cutting, a cross angle, said cross angle being defined by parallel projections of said first and second cutting edges (4; 5) on a projection plane defined by the flat element to be cut; said controlling means (17; 19; 29; 30) being configured for controlling said thrust means (15) such as to maintain said cross angle constant.
Device according to any one of claims 7 to 9, wherein said controlling means comprises a drive shaft (17) and a cam driving system operationally interposed between said drive shaft (17) and said thrust means.
Device according to claim 10, wherein said cam driving system comprises a cam member (19) rotated by said drive shaft (17), said cam member (19) having, in particular, at least a fifth cam profile (29) coupled with a fifth cam-following member (30) connected to said thrust means to drive a rotation of one blade with respect to the other; said thrust means comprising, in particular, an adjusting carriage (15) that is movable in an adjusting direction (16) driven by said fifth cam-follower member (30) and configured for thrusting said first blade (2); said cam member (19) having, in particular, at least a second cam profile (22) coupled with a second cam-following member (23) that is in turn connected to said first carriage (7) to drive the reciprocating motion thereof in the cutting direction; said second cam-following member (23) being, in particular, connected to said first carriage (7) by a further cam member (24) having a third cam profile (25) connected to a third cam-following member (27) that is in turn connected to said first carriage (7); said moving means comprising, in particular, a second carriage (8) that carries said second blade (3) and is movable with a reciprocating motion in a motion direction that is transverse to the advancing direction (6) and to the flat element, said further cam member (24) having, in particular, a fourth cam profile (26) connected to a fourth cam-following member (28) that is in turn connected to said second carriage (8) to drive the reciprocating motion thereof.
Device according to claim 11, wherein said moving means comprises a main carriage (9) that carries said first carriage (7) and is movable with a reciprocal movement in the advancing direction (6) in a manner that is coordinated with the advance of the flat element to be cut, said cam member (19) having at least a first cam profile (21) coupled with a first cam-following member (20) connected to said main carriage (9) to drive the reciprocating motion thereof.
Device according to any one of claims 6 to 12, wherein said thrust means comprises an adjusting carriage (15) that is movable in an adjusting direction (16) and is configured for thrusting said first blade (2); elastic means (33) being operationally associated with said adjusting carriage (16) to transmit said thrust to said first blade (2).
Device according to any preceding claim, wherein said moving means comprises a main carriage (9) that carries said first carriage (7) and is movable with a reciprocal movement in the advancing direction (6) in a manner that is coordinated with the advance of the flat element to be cut, said first and second blades (2; 3) taking on the closed configuration in at least a part of a forward stroke of the main carriage (9) and the open configuration in a backward stroke of the main carriage.
Device according to any preceding claim, wherein said moving means comprises a second carriage (8) that carries said second blade (3) and is movable with a reciprocating motion in a motion direction that is transverse to the advancing direction (6) and to the flat element.