GB2259473A

GB2259473A - A device for making incisions in strip material for tear-open wrappers

Info

Publication number: GB2259473A
Application number: GB9217140A
Authority: GB
Inventors: Maurizio Boldini; Frabetti Maurizio Muzzi; Alfonso Tomba
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 1991-09-11
Filing date: 1992-08-13
Publication date: 1993-03-17
Anticipated expiration: 2012-08-13
Also published as: IT1253018B; GB9217140D0; GB2259473B; DE4229387A1; ITBO910321A0; ITBO910321A1

Abstract

Tear-open tab U-shaped incisions are made in a continuous strip (4) of wrapping material by a device comprising a power driven feed roller (2), a rotary cutter (5) and a reaction roller (6), rotatable about mutually parallel axes transverse to the feed direction of the running strip (4), which is directed between the cutter (5) and the reaction roller (6). The reaction roller (6) is connected mechanically by an idle roller (8) to a drive (7) and set in rotation about its own axis at the same tangential velocity as the cutter (5), at least during the cutting stroke when the reaction roller (6) and the cutter (5) enter into mutual contact. <IMAGE>

Description

1 A device for making incisions in strip material for tear-open wrappers

The present invention relates to a device by means of which to make incisions in strip material of the type used for tear-open wrappers. In particular, the invention relates to a device capable of effecting cuts on a previously weakened or perforated line in a strip of wrapping material, or alternatively along a fillet of tougher material fastened to one face of such a strip. The purpose of the cut in question is to create a tongue or tab which, once a discrete length of the strip material has been folded around a commodity to form a wrapper, can be pulled upwards in such a way as to tear open the wrapper along a prescribed breaking line. A typical example is provided by the wrappers fashioned from lengths of heat-sealable strip material which are used to envelop a variety of commodities such as packets of cigarettes and sweets, both singly and in groups. The incision is made with a device that consists essentially in a power driven infeed roller over 2 which the continuous strip material is directed, drive means positioned beyond the device, by which the strip is drawn forward, cutting means, and a freely revolving cylindrical reaction roller, all rotatable generally about mutually parallel axes disposed normal to the feed direction. The cutting means consist in a power driven roller of which the revolving surface affords a slot, and mounted within the slot, a cutting tool embodied typically as a blade bent round into a U formation. The strip of material is fed forward, passing over the power driven cutting roller, which rotates at a tangential velocity identical to the feed rate of the strip, and in contact with the freely revolving reaction roller, in such a way that the blade of the cutting means is caused to enter into contact periodically with the reaction roller and the strip emerges exhibiting U-shaped incisions at regularly spaced intervals determined by the rate of feed. Notwithstanding devices of this type are capable of producing faultless incisions, they have been found also to produce excessive wear on the cutting tool; in effect, rotating at a peripheral velocity equal to the linear velocity of the strip, the tool tends to strike somewhat violently against the reaction is 3 surface during execution of the cutting stroke by reason of the fact that the reaction roller, being freely rotatable, all too often remains motionless. Whilst it is true that the reaction roller could in theory be rotated by tangential contact with the running strip, it is clear in practice that such a solution cannot absolutely ensure the continuous and steady rotation of the reaction surface at the same velocity as the tool, not least in view of the characteristics of the strip material selected for wrapping commodities of the types mentioned above. The inevitable result is that frequent changes of tool are required, involving costs incurred by the need to shut off the entire wrapping machine with which the device is associated. The object of the present invention is to provide a device of the type described, in which the cutting tool can be assured a considerably longer working life than is obtainable with conventional devices utilized currently for the same purpose. The stated object is realized in a device according to the invention for making incisions in strips of material for tearopen type wrappers, comprising at least one power driven infeed roller of which the revolving surface is breasted in rolling contact 4 with a strip of wrapping material advancing at a rate of feed identical to the tangential velocity of the revolving surface, and-rotary cutting means operating in conjunction with a respective reaction roller at a tangential velocity equal to that of the infeed roller, hence to the rate of feed of the advancing strip, characterized in that the reaction roller is connected mechanically to drive means, and rotated about its own axis by the drive means in contrarotation and at a tangential velocity substantially equal to that of the rotary cutting means, at least during the part of the cutting operation in which the reaction roller and the cutting means are brought into mutual contact. The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which: -fig 1 shows a length of strip material, in plan, from which to fashion a tearopen type wrapper; fig 2 illustrates a product enveloped in a wrapper obtained from the strip of material as in fig 1 and fashioned in part by the device according to the invention; - fig 3 illustrates the essential components of the device according to the invention, in a schematic side elevation; -fig 4 is a detail of one of the components shown in fig 3, viewed in axial section. Referring to the accompanying drawings, 1 denotes a device according to the invention, in its entirety; the device consists essentially in a power driven cylindrical infeed roller 2, rotary cutting means 5 and a cylindrical reaction roller 6, disposed with axes of rotation mutually parallel and normal to the feed direction followed by a continuous strip 4 of wrapping material directed through the device. The cutting means 5 are embodied as a cylindrical roller 9 and at least one cutting tool 10 or blade of which the cutting edge exhibits a U profile and is accommodated in a corresponding recess or slot afforded by the revolving surface of the roller 9. The two rollers 9 and 6 are positioned on opposite sides of the strip 4, their centres of rotation separated by a distance such as will ensure during rotation that the tool 10 enters into contact with the reaction roller 6 and produces a corresponding incision 11 in the running strip 4; in the example of figs 1 and 2, the incision coincides with a tear fillet 12 fashioned from a material tougher than that of the strip and applied longitudinally to one 6 of its two faces. Each such incision 11 creates a corresponding tab 14 in the strip 4 that can be grasped and pulled to tear op'en the wrapper formed around a relative commodity, as shown in fig 2. Also shown in fig 3 are two cylindrical rollers 13 contrarotating in mutual contact along a straight line generator, thus constituting pinch rolls by means of which to draw the strip 4 forward; these rollers 13, needless to say, will be positioned beyond the cutting means 5 and the infeed roller 2 in relation to the feed direction F of the strip 4 of material. In the device 1 according to the present invention, the reaction roller 6 is connected mechanically to drive means 7 by which it is set in rotation about its axis substantially at the same surface velocity as the cylindrical roller 9 of the cutting means 5 and in the opposite direction, at least during the cutting stroke. Thus, the cylindrical roller 9 and the reaction roller 6 operate in contrarotation, as indicated in fig 3 by arrows denoted G1 and G2. In a preferred embodiment of the device 1 according to the invention, the drive means 7 to which the reaction roller 6 is mechanically connected are one and the same as the infeed roller 2 (see fig 3).

7 As discernible in fig 3, the mechanical connection is provided by an idle roller 8 positioned between the reaction and infeed rollers 6 and 2, disposed parallel to both and in contact with each along a respective straight line generator. The idle roller 8 is embodied in resilient material and of interchangeable design, in order that the tangential velocity of the reaction roller 6 can be altered according to the tangential velocity of the cutting means 5. To this end, the infeed roller 2 and the idle roller 8 are supported in such a way that their axes can be adjusted for position, and more exactly, moved nearer to or farther from the reaction roller 6 to permit of varying the relative distance between centres according to the diameter of the idle roller 8. By way of example, fig 4 schematically illustrates a likely embodiment of the system for adjusting and altering the position of the axes of the infeed and idle rollers 2 and 8, which consists in a pivot 15 supported such that it can be rotated about its own axis by suitable adjustment means (conventional, therefore not illustrated) and locked in position once the adjustment has been effected. The pivot 15 is associated rigidly and eccentrically with the 8 shaft 16 of the roller 2 or 8; thus, rotation of the pivot 15 in one or other direction results in a corresponding movement of the7roller 2 or 8 toward or away from the reaction roller 6.

9 claims A device for making incisions in strips of material for tearopen type wrappers, comprising, at least, a power driven infeed roller of which the revolving surface is breasted in rolling contact with a strip of wrapping material advancing at a rate of feed equal to the tangential velocity of the revolving surface, and rotary cutting means operating in conjunction with a respective reaction roller at a tangential velocity equal to that of the infeed roller, hence to the rate of feed of the advancing strip, characterized in that the reaction roller is connected mechanically to drive means, and caused to rotate about its own axis by the drive means in contrarotation and at a tangential velocity substantially equal to that of the rotary cutting means, at least during the part of the cutting operation in which the reaction roller and the cutting means are brought into mutual contact.

2) 3) 4) r 6) A device as in claim 1, wherein the drive means to which the reaction roller is connected mechanically are one and the same as the infeed roller.

A device as in claim 1, wherein the drive means are one and the same as the infeed roller, to which the reaction roller is connected mechanically by way of an intermediate idle roller embodied in resilient material, disposed parallel to and in contact with the infeed roller and the reaction roller.

A device as in claim 3, wherein the idle roller is interchangeable with rollers of different diameter according to the tangential velocity of the rotary cutting means.

A device as in claim 3, wherein the infeed roller and the idle roller are supported with their axes adjustable for position by movement toward and away from the reaction roller, in such a way as to allow of varying the distance between centres of the axes according to the diameter of the idle roller.

A device for making incisions in strip material for tear-open wrappers, substantially as described with 11 reference to the figures of the accompanying drawings.