DEVICE FOR DIVIDING A CONTINUOUS WEB OF WRAPPING MATERIAL INTO SUCCESSIVE SINGLE SECTIONS

Abstract: The invention refers to the devices for dividing a continuous web of wrapping material into succesive single sections of a same length. These devices comprise a rotary cutting roller (1) with one or more angularly equispaced peripheral radial blades (7), the cutting edge of which is parallel to the axis of shaft (6) for driving in rotation the said cutting roller (1), and a rotary counter-roler (19) having one or more peripheral anvils (18) that cooperate each with a blade (7) on the cutting roller (1). According to the invention, the blade or blades (7) are each secured to a projecting blade-carrying member (8) which by elastic deformation is elastically yieldable in the radial direction toward the axis of shaft (6) for driving in rotation the cutting roller (1).

Description: The invention refers to the devices for dividing a continuous web of wrapping material into successive single sections of a same length, particularly for dividing a web of wrapping material into successive single bands used in the manufacture of filter-tipper cigarettes, which device comprises a rotary cutting roller with one or more angularly equispaced peripheral radial blades, the cutting edge of which is parallel to the axis of the shaft for driving in rotation the said cutting roller, and a rotary counter-roller having one or more peripheral anvils that cooperate each with one blade on the cutting roller, and which is possibly provided with suction ports for holding onto the counter-roller the single sections cut from the web fed around the counter-roller. In these devices, the cutting of the web is ef­ fected by parting it off, that is to say, the web is simultaneously engaged over its entire width by the cut­ ting edge of each blade on the cutting roller, and by one blow it is cut off against the respective anvil on the counter-roller. The cadenced blows of the cutting roller blades on on the counter-roller anvils produce noise and vibrations. To obviate to this inconveniences, devices of the above disclosed type have been proposed, in which the blades are not fixedly secured to the cutting roller, but are so mounted as to be radially slidable thereon between lateral guide walls, and as to be urged radially outward as far as an abutment stop member by return helical or cup springs which allow an elastic retraction of each blade when the blade hits against the associated anvil, in order to reduce the noise and dampen the vibrations. This solution however presents some other inconveniences. In fact, so-called fretting phenomena occur, that is to say, abrasion or corrosion phenomena due to friction, which affect above all the springs and in a short time annihilate their efficiency. To replace the springs with special elastomers is not the best solution of the problem, since these materials although being capable to maintain their elastic properties at the high temperatures produced by the deformation work, allow only small elastic retrac­ tions of the blades. Moreover, the slidable embodiment of the blades involves a considerably complicated construction, while the tobacco dust may penetrate between the guide surfaces, whereby the sliding of the blades is made difficult. A further inconvenience of the known cutting devices of the above disclosed types resides in a quick and irregular wear of the blade cutting edges due to any inevitable inexactness in positioning the blades with respect to the associated anvils on the counter-roller. In fact, each blade generally hits against the associated anvil at first with one end and then with the entire length of its cutting edge, which will be very soon the cause of defective cuts. To obviate to such an inconve­ nience, it is known to use blades which are tiltable in radial planes passing through the axis of the cutting roller. At the same time, each blade is elastically loaded in the longitudinal direction by means of elements sliding along both sides of the blade. The said sides of the blade are oblique sides which converge in the outward direction, and at the first cut the elastic load acting thereupon puts the blade straight, so that it is definitely arranged when its cut­ ting edge is not initially parallel to the surface of the respective anvil. The construction of these devices how­ ever is a very complicated one. The invention aims to eliminate the aforementioned inconveniences by reducing the excessive noise of the cutting devices of the type as disclosed at the beginning, and preventing any movements between the contacting surfaces, as well as the premature wear of the blades, resulting from a defect of parallelism of the blades to the associated anvils. This aim is attained by the invention in that the blade or blades are each secured onto a projecting blade-­ carrying member which by elastic deformation is elastically yieldable in the radial direction toward the axis of the shaft for driving in rotation the cutting roller. The said projecting blade-carrying member can be either made of one piece with the cutting roller skirt, or it may be added and rigidly secured thereto. The elastic radial yieldability of the projecting blade-carrying members considerably reduces any noise produced by the blades hitting against the respective anvils. The elastic radial yielding of the blades however occurs through a corresponding elastic deformation of the projecting blade-carrying members, whereby any relative movement between the contacting surfaces, and any movement of the lateral guides is prevented, so that all the in­ herent inconveniences are eliminated. Moreover, the projecting blade-carrying members have a limited resi­ stance to torsional stress, so that they can be twisted in such a manner as to amend any defect of parallelism bet­ ween the cutting edges of the blades and the associated anvil. Subordinately, the invention provides a particular method of assembling the cutting devices of the above-­ disclosed type, having projecting blade-carrying members. The features of the invention and the advantages arising therefrom will appear more in detail in the following specification of one preferred embodiment there­ of, shown by way of a non-limiting example in the accom­ panying drawings, in which: Figure 1 is an axial sectional view of the cutting roller. Figure 2 is a cross-sectional view of a projecting blade-carrying member in rest condition. Figure 3 is a cross-sectional view of a projecting blade-carrying member at the moment in which the respective blade hits against the associated anvil. Figure 4 is a cross-section through one half of the cutting roller. Figure 5 is a cross-sectional view of a blade and the respective blade-carrying member, which shows a pre­ ferred embodiment of fastening the blade to the blade-­ carrying member. Figure 6 is a top view of the blade according to Figure 5. Figure 7 is a cross-sectional view of two projec­ ting blade-carrying members with two additional damping elements. Figures 8 to 10 diagrammatically show some suc­ cessive steps of adjusting the blade-carrying members at the time of their assembly. In the Figures, numeral 1 denotes the cutting roller unit of a device for dividing a continuous web of wrapping material into successive single sections of a same length. The cutting roller 1 comprises a cylindrical skirt 2 which through bearings 3 is mounted onto a canti­ levered fixed support 4. The skirt 2 has its outward end secured to a disk 5 which in turn is secured to a driving shaft 6 rotatably mounted in support 4. On its perophery, the cutting roller 1 carries a plurality of blades 7 which are parallel to the axis of skirt 2 and are set in an angularly equispaced relation. Each blade 7 is fastened to a projecting blade-carrying member 8 which is elastically yieldable in the radial direction. In the preferred embodiment, the projecting blade-­ carrying members 8 are made of one piece with the skirt 2 of the cutting roller 1, and are formed by making in an outward raised of the said skirt 2 angularly equispaced through bores 9 which are parallel to the axis of the shaft for driving in rotation the cutting roller 1. Starting from each bore 9, an inclinated slit 10 is drilled in such a manner as to pass outwardly of the next bore 8, at some distance therefrom. Thus, each blade-carrying member 8 is given the shape of a projecting cleat-like member which is capable to elastically swing in the radial direction as easier as its cross-section at the bore 9 is thinner. The elastic deformability and particularly the twist of each blade-carrying member 8 can be increased by locally making bores or slots for conveniently reducing the resistance to torsional stress of the cross-section of the blade-carrying member 8 at its base, in correspon­ dence of the respective bore 9. On its outward side, each blade-carrying member 8 is provided with a housing for seating therewithin the respective blade 7, that has a square profile with four cutting edge. It is then possible to change the active cutting edge of blade 7 by inserting in a different angular position the blade 7 into the respective housing in the blade-carrying member 8. Each blade 7 can be fastened to the respective blade-carrying member 8 by means of two clamping rigid stirrups 11 which through screws 12 are secured to the blade-carrying member 8, and partially overlap the blade 7, as shown in the left-hand side of Figure 4, and in Figure 7. Preferably, however, in place of the rigid stirrups 11, two resilient platelets 13 are used for fastening the blades 7 to the respective blade-carrying member 8, as shown in the right-hand side of Figure 4, and in Figures 5 and 6. These resilient platelets 13 afford the advantage that it is not required to unloose any screws for removing and fitting in again a blade 7. Actually, since the platelets 13 apply drawn in its longitudinal direction out of the respective housing in the projecting blade-carrying member 8 by exerting a proper effort with a suitable implement. At their ends, the resilient clamping platelets 13 may present tabs 113 to be set into abutment with the head ends of blade 7. When fitting in or drawing out a blade 7, these abutment tabs 113 are elastically lifted so a to permit the passage of the blade. The radial outward movement of each projecting blade-carrying member 8 is limited by preferably adjustable abutment stop members. In the shown embodiment, on each side of the median raised portion of the skirt 2 of the cutting roller 1, from which side the projecting blade-­ carrying members 8 are made by means of bores 9 and slits 10, there is secured a ring 14 which in correspondence of each projecting blade-carrying member 8 has an indentation 15 in its side turned toward the said projecting blade-­ carrying member 8. In each indentation 15 there is housed an abutment block 16 with its projecting stop portion 116 overlapping the matching end 108 of the projecting blade-­ carrying member 8. Preferably, the projecting portion 116 of the abutment block 16 is shaped like a cylinder segment, and the matching end 108 of the blade-carrying member 8 is cylindrical on its outer side. Each abutment block 16 can be adjusted in the radial direction, so as to alter the outermost radial position of the respective projecting blade-carrying member 8. To this end, in the shown embodiment each abutment block 16 has an inclined outward side 216 which bears against the correspondingly inclined inward side 214 of ring 14. The abutment block 16 is also freely shiftable in the radial direction and can be locked in position by means of a locking screw 17 which is passed with radial play through a respective bore in ring 14 and is screwed in the abutment block 16. By unloosening the locking screw 17, the abutment block 16 can be freely shifted in the radial direction together with the screw 17. By tightening the screw 17, the abutment block 16 is clamped against the ring 14 and is locked by a wedge effect due to the cooperating inclined surfaces 214, 216. Each blade 7 of the cutting roller 1 cooperates in known manner with a respective peripheral anvil 18 of a counter-roller 19 on which the web to be divided into successive single sections is fed. The cutting of this web is effected by parting it off from above, through the action of the cutting edge of each blade 7 hitting against the respective anvil 18 on the counter-roller 19. To adjust the blades 7 in their proper position when assem­ bling the cutting roller 1, it should be proceeded as follows. When in their initial rest condition, the cutting edges of blades 7 lie on an ideal circle A having a radius R1, as shown in Figure 8. Before assembling the cutting roller, the blade-carrying members 8 are radially loaded by the aid of a special implement, so as to deflect them toward the axis of the cutting roller 1, and as to bring the cutting edges of blades 7 on an ideal circle B having a radius R2 which is smaller than the radius R1, as shown in Figure 9. The blade-carrying members 8 are kept in this position by the respective adjustable abutment blocks 16. The radius R2 of circle B is such that after the subsequent assembly of the cutting roller 1, the blades 7 do not contact the anvil 18 provided on the counter-roller 19, and which lie on a circle E having a radius R. After the assembly of the cutting roller 1, a blade 7 is moved in front of the relative anvil 18 on the counter-roller 19, and the respective blade-carrying member 8 is unlocked by means of the abutment blocks 16. The blade-carrying member 8 is partly unloaded, so that it elastically moves radially outward, as far as to cause the cutting edge of its blade 7 to bear against the anvil 18 on the counter-roller 19, as diagrammatically shown in Figure 10. Thanks to the capability of the blade-car­ rying member 8 to twist elastically, the respective blade 7 bears throughout the length of its cutting edge against the anvil 18 on the counter-roller 19, whereby any inevi­ table defect of parallelism is amended. After this operation, the cutting edge of blade 7 comes to lie on a circle C, the radius R3 of which is greater than the former radius R2, but is smaller than the initial radius R1 corresponding to its rest condition. Such as position of blade 7 is "stored", that is to say, is predetermined by means of the abutment blocks 16 which are adjusted and locked in a position in which their projecting portions 116 bear against the cylindrical outward surfaces 108 of the blade-carrying member 8, as it appears in Figure 2 and in the lower portion of Figure 1. The said operations are carried out for all the blade-carrying members 8 on the cutting roller 1. Then the distance between the shaft 6 of the cutting roller 1 and the shaft 20 of the counter-roller 19 is altered by means of an adjusting conventional eccentric device (not shown) and, more particularly, it is reduced to an amount K in such a manner that the cutting edge of a blade 7 bearing against its respective anvil 18 on the counter-­ roller 19 comes to lie, owing to the elastic radial yielding of the respective blade-carrying member 8, on an ideal circle D of a radius R4 which is smaller than the radius R3 by the said amount K, as shown in Figure 11. This difference K between the two radiuses R3 and R4 is the interference between the cutting edge of blade 7 and the respective anvil 18, which guarantees an excellent cutting action. During the operation, the blade-carrying members 8 are kept by the respective abutment blocks 16 in the position in which the edges of blades 7 lie on the circle C having a radius R3, as shown in Figures 2 and 10. Any time a blade 7 hits with its cutting edge against the anvil 18 on the counter-roller 19, the respective blade-carrying member 8 elastically yields radially by the amount K, as shown in Figures 3 and 11. If need be, but not necessarily, the projecting blade-carrying member 8 may be supported radially by suitable resilient damping supports inserted into the slits 10 and consisting, for example, of springs 21 or of blocks 22 of an elastomer material, as shown in Figure 7.

Claims: 1. A device for dividing a continuous web of wrapping material into single successive sections of a same length, particularly for dividing a web of wrapping material into successive single bands used in the manu­ facture of filter-tipped cigarettes, which device comprises a rotary cutting roller (1) provided with one or more angularly equispaced peripheral radial blades (7), the cutting edge of which is parallel to the axis of the shaft (6) for driving in rotation the said cutting roller (1), and a rotary counter-roller (19) having one or more peripheral anvils (18) that cooperate each with suction ports for holding onto the counter-roller (19) the single sections cut from the web fed around the counter-roller, characterized in that the blade or blades (7) are each fastened onto a projecting blade-carrying member (8) which by elastic deformation is elastically yieldable in the radial direction toward the axis of the shaft (6) for driving in rotation the cutting roller (1). 2. The device according to Claim 1, characterized in that each projecting blade-carrying member (8) is added and is rigidly attached to the skirt (2) of the cutting roller (1). 3. The device according to Claim 1, characterized in that each projecting blade-carrying member (8) is made of one piece with the skirt (2) of the cutting roller (1). 4.The device according to Claim 3, characterized in that each projecting blade-carrying member (8) is made from the skirt (2) of the cutting roller (1) by means of a bore (9) parallel to the axis of the shaft (6) for driving in rotation the cutting roller (1) and by means of an inclined slit (10) starting from the said bore (9) and opening into the peripheral surface of the cutting roller (1). 5. The device according to Claim 1, characterized in that the outward elastic radial movement of each projecting blade-carrying member (8) can be limited by means of adjustable abutment members preferably acting upon both ends of blade (7). 6. The device according to Claim 5, characterized in that the abutment stop members consist each of a radial ly shiftable abutment block (16) which by an extension thereof radially overlaps from the outside the respective end of a projecting blade-carrying member (8) and which through a locking screw (17) can be locked to a locking ring (14) integral of the cutting roller (1). 7. The device according to Claim 6, characterized in that the abutment block (16) and the respective locking ring (14) bear against each other through inclined or conical contact surfaces (216, 214) producing a wedge effect. 8. The device according to Claim 1, characterized in that each blade (7) is rigidly but removably locked in one respective housing in the projecting blade-carrying member (8). 9. The device according to Claim 8, characterized in that each blade (7) is locked in its housing within the respective projecting blade-carrying member (8) by means of two resilient platelets (13) which overlap the blade (7) from opposite sides, and which are fastened, for example by means of screws (12), to the respective projecting blade-carrying member (8), the said resilient platelets (13) being so made that they allow to axially remove and fit in a blade (7) without having to unloose the screws (12) fastening them. 10. The device according to Claim 9, characterized in that the resilient platelets (13) overlap the blade (7) with teeth or segments which are separate or spaced apart from one another. 11. The device according to Claim 1, characterized in that each projecting blade-carrying member (8) is elastically twistable to a certain extent. 12. The device according to Claim 11, characterized in that each projecting blade-carrying member (8) is provided with one or more bores or slots for rendering it twistable as required. 13. The device according to Claim 1, characterized in that each projecting blade-carrying mamber (8) is supported by one or more resilient and/or damping elements (21, 22). 14. A method for adjusting a blade (7) when as­ sembling the device according to Claim 1, characterized in that the cutting roller (1) is mounted with the pro­ jecting blade-carrying member or members (8) being kept in a position in which they are radially loaded toward the axis of the shaft (6) for driving in rotation the cutting roller (1) (circle B having a radius R2), whereupon each projecting blade-carrying member (8) is partly unloaded so as to cause the cutting edge of its blade (7) to bear against the respective anvil (18) on the counter-roller (19) (circle C having a radius R3 R2), and the abutment stop members (16) for the projecting blade-carrying member (8) are adjusted on the corresponding radial position of this member, whereupon the distance between the shafts (6-20) of the cutting roller (1) and the counter-roller (19) is reduced to the value (K) corresponding to the required cutting interference between the cutting edge of blade (7) and the respective anvil (18).

Inventors: GHERARDI, GIAN LUIGI
Applicants: SASIB S.P.A.
Application year: 1986
Main classification: A24C5
IPC codes: A24C5, B26D7