EP0888875A1

EP0888875A1 - A device for applying tear-strips

Info

Publication number: EP0888875A1
Application number: EP97111249A
Authority: EP
Inventors: Pier Carlo Scaliti
Original assignee: Ferrero OHG; Ferrero SpA; Soremartec SA
Current assignee: Ferrero OHG; Ferrero SpA; Soremartec SA
Priority date: 1997-07-04
Filing date: 1997-07-04
Publication date: 1999-01-07

Abstract

The device comprises a rotary cutter (118) provided with at least one blade (120) for cooperating with a fixed counter-blade (122) so as to form the tear-strips as a result of a transverse cutting action performed on a sheet material (B). The tear-strips (T) thus formed are restrained on the respective blade (120) by a vacuum effect for transfer and application to a sheet of wrapping material (F). The rotary cutter (118) has, in the region of the or each blade (120), an insert (150) the radially outer end (130a) of which defines the mouth of the vacuum means which restrain the tear-strips (T). The insert is movable between a retracted position in which the outer end (130a) is shielded by the cutting edge (120a) and by the respective blade (120) and a projecting position in which the outer end (130a) of the insert (150) projects beyond the cutting edge (120a) of the respective blade (120) to favour the movement for the application of the tear-strips (T) to the sheet of wrapping material (F).

Description

The present invention relates to a device for applying tear-strips according to the preamble to Claim 1.

A device of this type is known, for example, from IT-B-1 041 468 (Ferrero) to which GB-A-1 558 998 corresponds.

These prior documents describe a device which can apply the aforesaid tear-strips by arranging them transversely relative to the direction of advance of the wrapping material. The latter is usually constituted by a ribbon of sheet material which is to form wrappers for packaging products such as food or confectionery products.

In particular, the aforementioned prior documents address the problem of preventing the application of transverse tear-strips from resulting in a need to render the forward movement of the wrapping material intermittent, at least locally. This selection is difficult to reconcile with the very fast speeds of advance which the material is intended to reach in recently-produced packaging machines, particularly in those of the type known as "flow-pack", "form-fill-seal", or "FFS" packaging machines. The solution described in the above-mentioned prior documents provides for the tear-strips to be formed by transverse cutting of a further ribbon of sheet material. The individual tear-strip is then transferred to the wrapping material by means of a rotary member which also acts as a striker element during the cutting of the individual tear-strips and/or as an applicator member for applying the tear-strips to the wrapping material.

In the solutions described in IT-B-1 041 468 or GB-A-1 558 998 the aforementioned rotary member is configured substantially as a roller with two transfer elements mounted in diametrally-opposed positions. In use, one of the transfer elements receives a tear-strip just formed as a result of a cutting action performed by a cutter located in a fixed position relative to the structure of the device. At the same time, the diametrally-opposed transfer element cooperates with a sheet of wrapping material in order to deposit a tear-strip formed in a previous cutting operation.

The object of the present invention is to provide a device of the type specified above in which the operation to cut and apply the tear-strips can be rendered quicker and more efficient.

According to the present invention, this object is achieved by means of a device having the specific characteristics recited in the following claims.

The invention will now be described, purely by way of non-limiting example, with reference to the appended drawing which corresponds essentially to a side elevational view, partially sectioned for clarity, of a device for applying tear-strips according to the invention.

In the appended drawing, a device for applying tear-strips is generally indicated 10. This is a device which, as a whole, goes back the solution described in IT-B-1 041 468 and GB-A-1 558 998, to which reference may usefully be made for a general description of the operating criteria of the device 10.

The device in question is usually intended to be associated with a packaging machine, for example, of the type generally known as a "flow-pack" or "FFS" packaging machine. These are packaging machines widely known in the art, the characteristics of which do not need to be described in detail herein and, moreover, are not relevant for the purposes of an understanding of the invention.

For this purpose, it will suffice to note that a machine of the type specified above is intended to be supplied with a ribbon of sheet material F which is to form wrappers for packaging the articles in the packaging machine. The ribbon of sheet material F is unwound from a respective roll, not visible in the drawing but theoretically located at the top of the drawing on the right-hand side, in order then to be transferred towards the so-called "shaper" of the packaging machine; this element is also not shown in the drawings but may be imagined theoretically to be located at the bottom of the appended drawing on the right-hand side.

The sheet material F may be constituted, for example, by heat-sealable plastics material or aluminium, possibly of the type which is coated with plastics material, thus giving rise to a so-called "combined" wrapper. According to widely-known criteria, the material F is drawn from the supply roll and passed through the device 10 - where the tear-strips are applied - and is then sent towards the shaper of the packaging machine. Here the ribbon of sheet material F is closed onto itself so as to form a tubular semi-finished wrapper in which the articles to be packaged are inserted in a precisely regulated sequence. So-called transverse tear-strips T have to be applied to the sheet F in precisely spaced positions. These tear-strips are intended to permit regular and neat tearing of the wrappers or packages formed from the sheet F by the user in order to eat, or in general, to use the packaged articles.

In the embodiment illustrated (which, it is stressed, is an example and should not therefore be interpreted as limiting of the scope of the invention) it is assumed that, according to a preferred but not essential solution, the device 10 operates on the ribbon of sheet material F in the region of a portion F1 thereof which extends substantially vertically from an upper deflection roller 100 towards a lower deflection roller 102. All of this takes place during a downward movement from above at a given speed which should be kept as constant as possible since it is linked with the speed of operation of the packaging machine (not shown).

Seen in its most general aspects, the device 10 can be regarded as being constituted by a set of functional elements or sub-units.

The first of these sub-units is constituted by a source 104 for supplying an additional ribbon of sheet material B which is to be cut transversely relative to its direction of advance so as to form the individual tear-strips T to be applied to the sheet material. In the embodiment illustrated, the source is constituted by a roll of the material B associated, with the interposition of a set of tensioning rollers, generally indicated 16, with a withdrawal unit 106 constituted, for example, by a roller 108 driven by a respective motor 108a, with an associated opposed pressure roller 110. Downstream of the unit constituted by the roller 108 and the opposed roller 110, a guide member 114, for example, with a slot, is provided and constitutes the output of the source for supplying the ribbon B.

The function of the withdrawal unit 106 is to unwind the sheet material B from the respective roll, causing it to emerge from the member 114 in steps, the size of each step being equal to the width of the tear-strips T to be formed (typically a few mm).

Downstream of the withdrawal unit 106 (naturally, the term "downstream" refers to the direction of advance of the sheet material B, which is from left to right in the appended drawing), a cutting unit 116 is mounted on the framework of the device 10 and comprises a cutter comprising a rotary body 118 having at least one blade 120 with a cutting edge 120a. The blade, or rather the cutting edge 120a, extends along a generatrix of a theoretical cylindrical surface the principal axis of which corresponds to the axis of rotation X 118 of the body 118.

In the embodiment illustrated (which - it is again pointed out - is an example) the body 118 is constituted in practice by a roller or cylinder which rotates about the axis X 118 under the action of a motor (not visible in the drawings) and which carries two blades 120 located in diametrally opposed positions. The rotary cutter 118 can act on the sheet material B coming out of the guide member 114, cutting it into pieces of precisely the desired length corresponding to the width of the tear-strips T. This takes place in cooperation with a fixed blade (or counter-blade) 122 mounted on the framework of the device 10 with its cutting edge extending horizontally immediately downstream of the output of the guide member 114. It is clear from an observation of the drawings that the body 118 rotates clockwise as seen in the drawing; the ribbon B is cut into pieces as a result of the cutting action performed by the cutting edges 120a of the blades 120 and the counter-blade 122, that is, by a movement which takes place locally in the same direction as (although, naturally, at a faster speed than) the movement of the ribbon B out of the guide member 114.

Before the structure of the body 118 and of the members associated therewith are described further, it is appropriate to mention the presence of a further rotary member 126 situated on the opposite side of the rotary body 118 to the withdrawal unit 106. The rotary member 126 also has a generally carousel-like structure and can rotate about a respective axis X 120. The rotary member 126 carries on its periphery at least one (and, in the embodiment shown, two) diametrally-opposed striker elements or blocks 128 for cooperating with the blades 120 in accordance with criteria which will be described further below.

In general, all of the rotating members described above move about parallel axes generally oriented horizontally with reference to the overall geometry of the device 10 shown in Figure 1. Although this selection is preferable, it is not, however, essential for ensuring the operation of the device 10 on the basis of the principles which will now be described.

The ribbon of sheet material F (the wrapping material) is advanced at a constant speed determined by the speed of operation of the packaging machine with which the device 10 is associated. The members which draw off the additional sheet B are controlled (in a known manner which does not need to be described in detail herein) so as to unwind the material B in steps, the size of each step being equal to the width of the tear-strips T to be formed.

The ribbon B is cut and the tear-strips T are consequently formed as a result of the interaction of the rotary blades 120 with the fixed counter-blade 122. For this purpose, as can best be appreciated from an examination of the drawing, the blades 120 and the counter-blade 122 preferably have complementary scissor-like profiles.

The tear-strips formed (at least partially dynamically) as a result of the cutting action on the strip B are transferred from the cutting unit 116 towards the sheet of wrapping material F by the blades 120 themselves. These blades carry respective associated restraining elements formed (in the embodiment illustrated, which is an example, since the same restraining action may also be performed in a different manner, for example, mechanically) in the form of ducts 130 (usually of flattened shape so as to have, on the outer surface of the rotary cutter 112, respective mouth portions 130a substantially comparable to slots (possibly divided up along their length) formed in respective inserts 150 mounted in the body 118. The tear-strips T just formed are intended to be restrained on the ducts 130 (according to known criteria). This is achieved by virtue of the presence, in the rotary body 118, of ducts 132 connected to a source of a vacuum (a sub-atmospheric pressure) by means of respective ducts, schematically indicated 132 in the drawings.

The tear-strips T are thus transferred from the cutting unit 116 towards the sheet F and are applied thereto by a precisely synchronized movement, that is, in a manner such that the tangential velocity of the blades 120 is practically identical to the (linear) velocity of the portion F1 of the sheet material F when the or each blade is close to the ribbon F. This takes place by the synchronization (in known manner) of the speed and phase of the rotary movements of the rotary blade 118 and of the further rotary member 126 (which is shown here as having the same diameter, although this solution is not essential per se) so that each time a blade 120 deposits a respective tear-strip T on the sheet material F (acting on the left-hand face thereof as seen in the appended drawing), the other face of the sheet F (the right-hand face in the drawing) is in contact with and bearing on a respective striker block 128 of the member 126. In these conditions, the tear-strip T and the region of the portion F1 of the sheet material F to which it is applied are gripped between the blade 120, acting as an applicator member, and a respective striker block 128, acting as an abutment member.

It can also be seen from the drawing that the striker blocks 128 are mounted on the body of the member 126 in respective radial seats 128a which allow the striker blocks 128 a certain freedom of movement in a radial direction relative to the member 126. This enables each striker block 128 to withdraw slightly inwards relative to the rotary member 126, overcoming the reaction of respective springs 138. In the drawing, only the springs 138 associated with the striker block 128 mounted on the right-hand side of the member 126 in the drawing are shown; naturally, however, exactly the same arrangement is provided for the other striker block 128. The gripping of the sheet material F and of the tear-strip T being applied thereto at a particular time, can thus be achieved in the form of a resiliently-loaded grip ensured by the ability of the striker block 128 to yield resiliently.

An important characteristic of the solution according to the invention is that the insert (if there is only one blade 120) or inserts 150 in which the ducts 130, the respective mouths 130a of which restrain the tear-strips T on the rotary blade 118, are formed, are mounted on the body 118 so as to be movable radially in a manner substantially similar to that described above with reference to the striker blocks 128 mounted on the rotary member 126.

The inserts 150 are therefore able to move radially relative to the body 118, that is, in general, towards and away from the axis X 118. It is not, however, essential for the inserts 150 to be flat and/or arranged in a diametral plane relative to the cylindrical body of the cutter 118; the inserts 150 could also be of a different shape, for example, a curved shape, and/or could be mounted obliquely on the body of the cutter 118 so as in any case to be movable between:

a first, retracted position, that is, the position adopted by the insert 150 which, in the instantaneous position of rotation shown in the drawing, is on the right-hand side of the body 118, and
a second, extended position, that is the position adopted by the insert 150 which is on the right-hand side of the body of the cutter 118.

In the retracted position, the mouth 130a of the duct 130 formed in the body of the insert 150 is, so to speak "shielded" by the blade 120 adjacent thereto (in a downstream position in the direction of rotation of the body 118) so that the cutting edge 120a of the blade constitutes the outermost projection of the respective region of the curved surface of the body 118. The cutting edge 120a is thus free to cooperate with the counter-blade 122 (in the region which, in the following claims, is called the "first region" of the path of the blade 120/cutting edge 120a) to cut the tear-strips T from the ribbon B.

As it moves outwardly relative to the body 118 towards the position shown on the right in the drawing, however, the mouth portion 130a of the duct 130 projects at least slightly beyond the cutting edge 120a of the respective blade 120 and, by this movement, brings the tear-strip T applied thereto to a projecting position ideal for transfer to the sheet F (in the region of the path called the "second region" of the path in the claims).

The movement of the insert or inserts 150 between the two positions described in a manner such that it adopts or they adopt the radially outer position in the angular position of its or their orbital movement in which the transfer of the tear-strip T to the ribbon F takes place can easily be brought about - for example - by means of one or more cams 152 (the profile of which is shown schematically by a broken line in the drawing) or by equivalent actuator means. There may be one, or even better, two cams situated at the ends of the body 118 for cooperating with respective follower rollers 154 (the respective profile also being shown by a broken line in the drawings) which support the inserts 150 at their ends. The cam or cams 152 are usually formed so as to have a projecting lobe 156 in the angular region (the second region) of the path of movement of the blades 120 in which the transfer of the tear-strip T to the ribbon F takes place (and hence in the portion of the path farthest to the right in the appended drawing), with provision, however, for them to be returned to and kept in the radially retracted position for the rest of the path.

This return and keeping can be achieved under the effect of resilient biasing members or, according to an embodiment which is preferred on account of the speed of rotation normally envisaged for the cutter 118 in operation, as a result of a positive action, given that the cam or cams 152 are preferably configured in slot form, by the shaped profile defining a sliding seat for the follower rollers 154.

Claims

A device (10) for applying, to a ribbon of sheet wrapping material (F) moving in a given direction, tear-strips (T) oriented transverse the direction of advance of the ribbon, the device comprising:

guide means (100, 102) defining a path of advance of the ribbon of sheet wrapping material (F) through the device (10),

supply means (104, 106) for supplying, from a respective output (114), a further sheet material for forming the tear-strips (T), and

cutting means (116) for cutting the further sheet material (B) so as to form the tear-strips (T),
characterized in that:

the cutting means (116) comprise a rotary body (118) on which at least one blade (120) is mounted and, as a result of the rotation of the rotary body (118) can follow a path passing through a first region, adjacent the output (114) of the supply means (104, 106) and a second region facing the path of advance defined by the guide means (100, 102) so that, in use, the rotary body (118) acts on the tear-strips (T) in order to pick them up in the first region and then apply them to the ribbon of sheet wrapping material (F) in the second region,

at least one respective insert (150) is associated with the at least one blade (120) and has an outer end (130a) which can perform a gripping action on the tear-strips (T) and is generally adjacent the blade (120), and

respective actuating means (152, 154, 156) are associated with the at least one respective insert (150) and, during the rotation of the rotary body, (118) move the at least one respective insert (150) relative to the rotary body (118) between a first position which is adopted at least in the first region of the path and in which the outer end (130a) of the insert (150) is retracted relative to the blade (120), and a second position which is adopted at least in the second region of the path, and in which the outer end (120a) of the insert (150) projects beyond the blade (120).
A device according to Claim 1, characterized in that the cutting means comprise a counter-blade (122) disposed in a fixed position adjacent the output (114) of the supply means (104, 106) for cooperating with the at least one blade (120) mounted on the rotary body (118) so as to cut the further sheet material (B) in order to form the tear-strips.
A device according to Claim 1 or Claim 2, characterized in that the rotary body (118) carries a plurality of associated blades (120), each associated with a respective insert (150).
A device according to Claim 1 or Claim 3, characterized in that the rotary body (118) carries at least one pair of associated, diametrally-opposed blades (120).
A device according to any one of Claims 1 to 4, characterized in that the at least one respective insert (150) carries the associated cam means (152 to 154) which can bring about the movement between the first position and the second position.
A device according to Claim 5, characterized in that the at least one respective insert (150) carries at least one associated respective drive roller (154) which follows the cam (152).
A device according to Claim 5 or Claim 6, characterized in that the cam means comprise a cam (152) in the form of a slot and in that the at least one insert (150) carries an associated drive element (154) which can cooperate with the slot cam (152) so as to bring about a positive translational movement of the at least one respective insert (150) between the first position and the second position.
A device according to any one of Claims 5 to 7, characterized in that it comprises a pair of cams (152) situated at opposite ends of the rotary body (118) for actuating the at least one respective insert (150).
A device according to any one of the preceding claims, characterized in that the at least one respective insert (150) is produced in the form of a generally hollow body (130) with the outer end (130a) constituting a gripping mouth which can perform a restraining action on the tear-strips (T) owing to a pressure gradient resulting from a sub-atmospheric pressure present in the at least one respective insert (150).
A device according to Claim 9, characterized in that at least one duct (132) extends through the rotary body (118) in order to connect the at least one respective insert (150) to means for generating a sub-atmospheric pressure.
A device according to any one of the preceding claims, characterized in that the supply means (104, 106) comprise at least one motor-driven movable member (108, 108a) which acts on the further sheet material (B) in use and can be advanced in steps, the size of each step identifying the width of the tear-strips (T).
A device according to any one of the preceding claims, characterized in that the supply means (104, 106) carry an associated guide element (114) for imparting to the further sheet material (B) a path of advance directed towards the cutting means (116).
A device according to any one of the preceding claims, characterized in that it also comprises, on the opposite side of the path of advance defined by the guide means (100, 102) to the rotary body (118), a movable member (126) provided with at least one striker block (128) which can cooperate with the at least one blade and with the respective insert (150) associated therewith in the second region so as to exert a gripping action on the tear-strips (T) and on the ribbon of sheet wrapping material (F) to which the tear-strips (T) are applied.
A device according to Claim 13, characterized in that the movable member (126) comprises a plurality of the said striker blocks (128).
A device according to either of Claims 13 and 14, characterized in that the at least one striker block (128) is mounted on the movable member (126) in a resiliently yielding manner (128a) so that the gripping action on the tear-strips (T) and on the ribbon of sheet wrapping material (F) is exerted as a result of a resilient pressure.