DE102007030977A1 - Cutting device for cutting a strip has a roller to rotate on a central swivel pin, a moving knife attached to the roller and fixed knife near the roller - Google Patents

Abstract

Attached to a roller (3), a moving knife (5) is slanted at a first angle regarding a central swivel pin (4). Fitted in a position near the roller, a fixed knife (6) works together the moving knife by sliding over it so as to apply a gradual cut like scissors to a strip (2) fed between the two knives. In respect of the central swivel pin, the fixed knife is slanted at a second angle equal to the first but opposed to it so as to be slanted in respect of the moving knife.

Description

TECHNICAL AREA

The The present invention relates to a cutting device for cutting a ribbon.

The The present invention finds advantageous application in an automatic Cigarette manufacturing or packaging machine to which the following description refers purely by way of example.

STATE OF THE ART

A automatic cigarette making machine includes a feeder unit for feeding Strips, each of which is gummed and used to one Filter with a cigarette portion of an adjacent cigarette rod or stabs connect to; and the strip feeding unit comprises a Cutting device to the individual strips of a paper tape in Transverse direction, which is unwound from a spool.

A automatic cigarette packing machine comprises a feeder unit for providing sheets or foils or sheets of packaging material, each of which is about a group of cigarettes is folded; and the packaging material sheet feeding unit or feed unit for feeding of leaves of packaging material includes a cutting device to transversely the individual leaves of packaging material to be separated from a band of packaging material or to be cut off, which is unwound from a spool. At a Packaging machine for the production of cigarette packs leads the Verpackungsmaterialblattzuführeinheit for example leaves from films of metal foil to packaging material during packaging material sheet feeding unit in a cellophane maker, sheets of heat-sealable Plastic packaging material provides.

Generally leads one Cutting device of a feed unit an automatic machine for packaging or packaging of cigarettes a scissor-like, ie point-wise cutting, by two mutually facing and counter-rotating Rolls, each one a number of sharp, evenly spaced carries spaced knife. The knives on or on a roller or a roller are in proportion to those of the other roll inclined at a predetermined angle or bevelled so only two cooperating knives on the two rollers a contact point on top of each other slip, which during the rotation of the rollers gradually moves, and the supplied between the two rollers band is gradually on cut the point of contact between the two interacting knives, around the band while scissor-like the rotation of the rollers.

An example of a cutting device of the type described above is in the patent US4943341A1 which describes a cutting device for cutting filter cigarette strips in a high speed filter assembling machine. The strips are successively cut by two counter-rotating rollers from a band, each having a number of uniformly spaced blades; and each knife on one roll defines, together with a knife on the other roll, shearing means for cutting the tape at successive points upon rotation of the rolls.

A Cutting device of the type described above proves to be expensive and bulky, as it has two counter-rotating rollers, each having a number of knives. To the costs and To reduce the dimensions, a cutting device has been proposed, which only has one roll, a number evenly from each other carries spaced, rotating knife; and a fixed one Knife acts cyclically with all rotating knives on the roll together.

However, in a cutting device comprising a fixed knife and a roller carrying a number of rotating knives, the distance between the edge of each rotating knife and the edge of the fixed knife is not constant during the cutting process. That is, since each rotating blade is slightly skewed relative to the rotational axis of the roller (a necessary condition for performing scissor-type cutting), the distance between the edge of the rotating blade and the axis of rotation (ie, the radius of the edge of the blade) rotating knife) along the knife is not constant. To overcome this drawback, it has been proposed to deform the fixed knife in the center to bring a central portion of the fixed knife closer to the roll, thus compensating for the distance differences between the edge of each rotating knife and the edge of the fixed knife. The solid knife may be deformed at the manufacturing stage, although this solution complicates the manufacture of the fixed knife and above all causes the fixed knife, which does not have a straight cutting edge, to be extremely difficult to grind. Alternatively, the solid knife may be deformed by means of screws pressing against the fixed knife at the assembly stage. However, this solution proves to be due to the high bending stiffness of the fixed blade mechanically complicated and offers only a rough, empirical and difficult to calibrate balance.

A Reduction of the effects of distance variations between the edge requires each rotating knife and the edge of the fixed knife a very small angle of inclination (eg less than 0.5 °) between every rotating knife and the fixed knife. A scissors cutting with However, a very small angle of inclination requires a considerable Power, which is at the expense of cutting precision.

Finally is a cutting device of the type described above with a complex maintenance connected (in particular with regard to downtimes), as it is to guarantee a high quality cut (i.e., straight, neat) is necessary, the knives are ground well to keep repeating them regularly, which means removing the knife and re-attaching it again to assemble and adjust the position of the knife precisely, as soon as it is installed again. Every grinding process uses this In addition, knife off and shortened it why it replaces after a certain number of grinding operations must become.

DESCRIPTION OF THE INVENTION

It An object of the present invention is a cutting device for cutting a tape, which are those described above Cons to handle disadvantages and at the same time cost-effective and can be easily produced.

According to the present The invention provides a cutting device for cutting a strip, as claimed in the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A not restrictive Embodiment of The present invention will now be described by way of example with reference to FIG the accompanying drawings, in which:

1 a schematic side view of a cutting device for cutting a strip according to the present invention shows, with some parts omitted or omitted for the sake of clarity;

2 a perspective view of the cutting device of 1 shows;

3 a plan view of a fixed blade of the cutting device of 1 shows;

4 a plan view of a movable blade of the cutting device of 1 shows.

PREFERRED EMBODIMENTS THE INVENTION

In 1 is with the number 1 a cutting device for cutting a tape 2 in their entirety.

The cutting device 1 includes a role 3 , which is about a central axis of rotation 4 perpendicular to the plane of 1 rotates; one at the roll 3 attached movable knife 5 ; and a solid knife 6 in a fixed position near the roller 3 is arranged to move with the movable knife 5 to interact and glide over this, between the two knives 5 and 6 supplied band 2 gradually or gradually scissor-like to cut.

In an alternative, not shown embodiment supports or supports the role 3 a number of moving knives 5 evenly around the roll 3 are spaced around each other.

In an alternative embodiment, not shown, the cutting device comprises 1 a number of solid knives 6 which are arranged in a number of suitably positioned carriers.

The moving knife 5 on the roll 3 is with respect to a rotation axis 4 Chamfered at a first angle of inclination; and the solid knife 6 is with respect to the axis of rotation 4 with a second inclination angle equal to and opposite to the first inclination angle, is inclined to incline with respect to the movable blade 5 beveled opposite. Each angle of inclination is usually between 0.5 ° and 2 ° (so the two knives 5 and 6 are bevelled with respect to each other at a total angle which is between 10 and 4 °). Preferably, each angle of inclination is an angle of 0.75 ° (so that the two knives 5 and 6 with respect to each other by a total of 1.5 ° beveled). In an alternative embodiment, not shown, based on the diameter of the roll 3 , short knives 5 and 6 for a very narrow band 2 be used; In this case, each inclination angle can be up to 45 ° (so that the two knives 5 and 6 with respect to each other by a total of 90 ° beveled, which is the best cutting requirement).

It should be noted that both knives 5 and 6 have an absolutely straight cutting edge, neither before nor after assembly in keinster Be mold deformed and therefore inexpensive, easy and fast to produce.

Trials and research show that the movable knife 5 and the solid knife 6 which are chamfered oppositely as described above, serve to allow a constant distance (ie gap) between the edge of the movable knife 5 and the edge of the fixed knife 6 to achieve throughout the cutting process. Considering the constant distance (ie gap) between the edge of the movable knife 5 and the edge of the fixed knife 6 Throughout the cutting process, the total angle of inclination between the knives can be 5 and 6 be relatively large (up to 90 ° for very short knives), so that a scissors cutting requires little force, which significantly improves the cutting precision.

The cutting device 1 includes a feed element 7 (shown schematically and usually comprises at least two driven rollers) for feeding a tape 2 between the fixed knife 6 and the movable knife 5 at an optimum feed rate depending on the feed angle of the belt 2 concerning the levels of the knives 5 and 6 , In the embodiment shown in the accompanying drawings, the band 2 for example, between the fixed knife 6 and the movable knife 5 at an angle of 30 ° with respect to the planes of the blades 5 and 6 and thus at an optimum feeding speed equal to 0.75 (75%) of the peripheral speed of the movable knife 5 is. It is worth mentioning that when the tape 2 is fed at the optimum feed rate, this is cut completely perpendicular to itself. The feeding speed of the tape may be slightly different from the optimum (especially around all possible formats of the tape 2 to be fair); in this case, the tape becomes 2 not cut completely perpendicular to itself. However, this minor imperfection is usually allowed because it does not affect the quality of the final product.

In a preferred embodiment, the movable knife comprises 5 and the solid knife 6 each two "V" shaped "arranged cutting edges or blades 8th to make a symmetrical, simultaneous double-scissors cut and so two V-shaped knives 5 and 6 (It is obvious that one V with respect to the other due to the opposite inclination angle or counter-inclination angle of each cutting 8th is inverted, so that one V is concave and the other is convex). The cutting 8th of the movable knife 5 and the solid knife 6 are preferably arranged in a V-shape, so that the symmetrical, simultaneous double scissors cut from the outer edges of the tape 2 towards the middle and a tearing of the band 2 in the middle section of the band 2 occurs, which is usually not visible in the final product. In an alternative embodiment, not shown, include the movable knife 5 and the solid knife 6 one cutting edge each 8th ,

The two cutting edges 8th of the movable knife 5 and the solid knife 6 are preferably arranged side by side and not interconnected so that the position of each cutting edge 8th regardless of the position of the other cutting edge 8th is adjustable to get a cut of better quality.

In a preferred embodiment, each blade has 8th the shape of a rectangular prism with a parallelogram-shaped base, two opposite larger side walls 9 and two opposite smaller sidewalls 10 perpendicular to the larger side walls 9 are; and four longitudinal edges 11 which are ground so that they have a cutting edge of the cutting edge 8th define are between the larger sidewalls 9 and the smaller side walls 10 every cutting edge 8th Are defined.

Every cutting edge 8th is preferably symmetrical with respect to at least one central axis to have at least two interchangeable cutting edges. In particular, every cutting edge 8th symmetrical with respect to two vertical central axes and thus has four interchangeable cutting edges, so that each cutting edge 8th can be used four times by turning it four times to work with its four cutting edges before it is ground or changed.

For every cutting edge 8th of the movable knife 5 includes the role 3 a seat 12 , which is a flat carrier surface or carrier surface 13 parallel to the central axis of rotation 4 having; and a larger sidewall 9 every cutting edge 8th of the movable knife 5 lies on or on the support surface 13 on. It is at least a fixing screw 14 provided that each cutting edge 8th of the movable knife 5 on the support surface 13 stops, through a through hole 15 in the cutting edge 8th introduced and in the role 3 is screwed. The inner diameter of each hole 15 is larger than the outer diameter of the fixing screw 14 to adjust the position of the movable knife 5 to allow or allow.

The seat 12 also includes a flat support surface or support surface 16 transverse to the central axis of rotation 4 and perpendicular to the support surface 13 ; and a smaller sidewall 10 every cutting edge 8th of the movable knife 5 lies on the support surface 16 on or on. At least one adjusting screw 17 is through a hole 18 through the support surface 16 screwed and presses on the cutting edge 8th of the movable knife 5 to the cutting edge 8th to move forward to the position of the cutting edge 8th concerning the position of the fixed knife 6 adjust. Preferably, two adjustment screws 17 for every cutting edge 8th intended.

For every cutting edge 8th the solid knife 6 includes the cutting device 1 a seat 19 similar to the seat 12 for every cutting edge 8th of the movable knife 5 , In particular, every cutting edge 8th the solid knife 6 to their seat 19 fitted, by at least one fixing screw 14 and if possible by a clamping device (not shown), which they diagonally on support surfaces of the seat 19 pulls (which therefore also define reference surfaces).

In a preferred embodiment, each blade comprises 8th of the movable knife 5 near the smaller side walls 10 respective longitudinal weakening elements to locally improve the longitudinal flexibility of the cutting edge. In particular, each weakening element is through a groove 20 defined, parallel to the longitudinal edges 11 is and in the larger sidewall 9 is formed, and serves to the longitudinal flexibility of the cutting edge 8th improve locally, to allow the cutting edge 8th in a blocking or inhibiting bends without breaking.

As mentioned above, the cutting device described above remains 1 the distance (ie the gap) between the edge of the movable knife 5 and the edge of the fixed knife 6 constant throughout the cutting process; and experiments show that the cutting device described above 1 can be adjusted quickly and easily and delivers high-quality cuts even at very high operating speeds.

The cutting device described above 1 is associated with less maintenance, which can be done extremely quickly, as every cutting edge 8th is symmetrical and therefore rotatable four times to work with its four cutting edges before being ground or changed, and because the position setting of each cutting edge 8th goes extremely fast. The cutting 8th the solid knife 6 are actually fixed in a given position and only the positions of the cutting edges 8th of the movable knife 5 be using the adjusting screws 17 set. The positions of the cutting edges 8th of the movable knife 5 are adjusted by the role 3 is simply set to two predetermined adjustment positions (eg, by using a calibrated adjustment device or template) and, alternatively, to the adjustment screws 17 the cutting 8th of the movable knife 5 is acted upon.

It is worth mentioning that every cutting edge 8th has four cutting edges, can be mounted in four different positions in the cutting device and works in any position with only one of its four cutting edges. When all four cutting edges are worn, the cutting edges become 8th successively changed as required. To make sure each cutting edge 8th in the right position has every cutting edge 8th preferably at least one asymmetrical reference hole (or asymmetrical reference notch).

The cutting device described above 1 has another advantage when with a band 2 made of pure aluminum or laminated or laminated foil (with a high aluminum content). In various known cutting devices, when a band of laminated aluminum foil is cut, the band adheres under pressure to the knife synchronously with the band. To overcome this drawback, it has been proposed to lubricate the foil band with oil or vaseline, although this is a very complex process and tends to soil the foil band. In the above-described cutting device 1 becomes the band 2 however, at a speed different from that of both the fixed blade 6 as well as the moving knife 5 fed and should therefore under pressure neither on the fixed knife 6 still on the movable knife 5 be liable. In other words, the significant speed difference between the tape should be 2 and the knives 5 and 6 prevent the tape 2 under pressure on the knives 5 and 6 liable.

It should be noted that the cutting device described above 1 can be advantageously used for cutting any type of belt but is particularly suitable for cutting a film strip to form sheets of packaging material used in a packaging machine for producing cigarette packets.

Claims (20)

Cutting device for cutting a strip; the cutting device ( 1 ) comprises: a roller or roller ( 3 ), which revolve around a central axis of rotation ( 4 ) turns; at least one movable knife ( 5 ), the role of 3 ) is mounted and with respect to the axis of rotation ( 4 ) is inclined at a first inclination angle; and at least one fixed or fixed knife ( 6 ) in a fixed position near the roller ( 3 ) is arranged and by sliding over with the movable knife ( 5 ) interacts between the two knives ( 5 . 6 ) supplied band ( 2 ) gradually scissor-like; the cutting device ( 1 ) characterized in that the fixed knife ( 6 ) with respect to the axis of rotation ( 4 ) with a second inclination angle which is equal to and opposite to the first inclination angle, is bevelled so as to be inclined with respect to the movable blade ( 5 ) opposite or beveled opposite. A cutting device according to claim 1, wherein each one Tilt angle between 0.5 ° and 10 lies. A cutting device according to claim 2, wherein each one Tilt angle is an angle of 0.75 °. Cutting device according to claim 1, 2 or 3, wherein a number of movable blades ( 5 ) around the role ( 3 ) is arranged around. Cutting device according to one of claims 1 to 4, in which the movable knife ( 5 ) and the fixed knife ( 6 ) two blades or blades ( 8th ) arranged "V" -shaped to make a symmetrical, simultaneous double-scissors cut. Cutting device according to claim 5, in which the cutting edges ( 8th ) of the movable knife ( 5 ) and the fixed knife ( 6 ) Are arranged "V" -shaped so that the symmetrical, simultaneous double-scissors cut from the outer edges of the strip ( 2 ) takes place towards the center. Cutting device according to claim 5 or 6, in which the two cutting edges ( 8th ) of the movable knife ( 5 ) and the fixed knife ( 6 ) Are arranged side by side and not connected to each other. Cutting device according to one of claims 1 to 7, and comprising a feed element ( 7 ) for feeding the tape ( 2 ) between the fixed knife ( 6 ) and the movable knife ( 5 ) with an optimum feed rate depending on the angle of inclination of the strip ( 2 ) with regard to the planes of the blades ( 5 . 6 ). Cutting device according to claim 8, in which the feeding element ( 7 ) the ribbon ( 2 ) between the fixed knife ( 6 ) and the movable knife ( 5 ) at an angle of 30 ° with respect to the planes of the blades ( 5 . 6 ) and at an optimum feeding speed equal to 0.75 of the peripheral speed of the mobile knife ( 5 ). Cutting device according to one of claims 1 to 9, in which the movable knife ( 5 ) and the fixed knife ( 6 ) at least one cutting edge ( 8th ) which is in the form of a right-angled prism having a parallelogram-shaped base and is symmetrical with respect to at least one central axis to have at least two interchangeable cutting edges. Cutting device according to one of claims 1 to 9, in which the movable knife ( 5 ) and the fixed knife ( 6 ) at least one cutting edge ( 8th ) which is in the form of a right-angled prism having a parallelogram-shaped base and is symmetrical with respect to two perpendicular central axes to have four interchangeable cutting edges. Cutting device according to one of claims 1 to 11, in which the movable knife ( 5 ) and the fixed knife ( 6 ) at least one cutting edge ( 8th ), which take the form of a right-angled prism having a parallelogram-shaped base, two opposing larger side walls (FIG. 9 ) and two opposite or opposite smaller side walls ( 10 ), which are perpendicular to the larger side walls ( 9 ) are; and between the larger side walls ( 9 ) and the smaller side walls ( 10 ) each cutting edge ( 8th ) are four longitudinal edges ( 11 ), each of which is ground or sharpened so as to define a cutting edge of the cutting edge ( 8th ) Are defined. Cutting device according to claim 12, in which the roller ( 3 ) a first seat ( 12 ) for the cutting edge ( 8th ) of the movable knife ( 5 ), the first seat ( 12 ) a flat first carrier surface or carrier surface ( 13 ) parallel to the central axis of rotation ( 4 ); and a larger side wall ( 9 ) of the cutting edge ( 8th ) of the movable knife ( 5 ) lies on the first support surface ( 13 ) on. Cutting device according to claim 13, wherein at least one fastening screw ( 14 ) through a first through hole ( 15 ) introduced by the cutting edge ( 8th ) of the movable knife ( 5 ) is formed through, and in the role ( 3 ) is screwed to the cutting edge ( 8th ) on the first support surface ( 13 ) to keep. Cutting device according to claim 13 or 14, in which the first seat ( 12 ) a flat second carrier surface or carrier surface ( 16 ) transverse to the central axis of rotation ( 4 ) and perpendicular to the first support surface ( 13 ) having; and a smaller side wall ( 10 ) of the cutting edge ( 8th ) of the movable knife ( 5 ) lies on the second support surface ( 16 ) on. Cutting device according to Claim 15, in which at least one second adjusting screw ( 17 ) in a second through hole ( 18 ) screwed through the second support surface ( 16 ) is formed through, and on the cutting edge ( 8th ) of the movable knife ( 5 ) presses the position of the cutting edge ( 8th ) adjust or adjust. Cutting device according to Claim 16, in which two second adjusting screws ( 17 ) for each cutting edge ( 8th ) are provided. Cutting device according to one of claims 13 to 17, wherein a second seat ( 19 ) for the cutting edge ( 8th ) of the fixed knife ( 6 ), the second seat ( 19 ) similar to the first seat ( 12 ). Cutting device according to one of claims 12 to 18, in which close to a smaller side wall ( 10 ) each cutting edge ( 8th ) comprises a longitudinal weakening element in order to locally improve or increase the longitudinal flexibility of the cutting edge. Cutting device according to claim 19, in which the weakening element is guided by a groove ( 20 ) defined parallel to the longitudinal edges ( 11 ) and in the larger side wall ( 9 ) is trained.