GB2235680A - Wrapping articles in metal foil - Google Patents

Abstract

In a method or apparatus for wrapping a plurality of articles in metal foil, in which a sheet of foil is wrapped around a line of articles so as to form a tube, the tube is pierced at a location between each pair of successive articles by orthogonally-arranged pairs of knives 15-18, and then is contacted by like pairs of folding elements 20-23 which cause the foil tube to tear forming flaps and severance of the tube at the location at which it has been pierced, and which fold the flaps inwardly against the articles. Each folding element may be paired with a respective knife for simultaneous movement therewith and the folding elements and knives moved at the same speed as the tube in its direction of advance during their operation. <IMAGE>

Description

METHOD AND APPARATUS FOR WRAPPING ARTICLES This invention relates to a method of and apparatus for wrapping articles in foils particularly articles which are fragile or easily collapsible.

Machines for wrapping articles, particularly food products, generally use plastics or metallised plastics film as the wrapping medium. This medium has the advantages of being both pliable and sufficiently strong to be pulled through a folding box or plate to form a tube around the product to be wrapped. Another advantage of such a plastics medium is that it can be heat sealed and severed by means of a simple rotary heater and knife.

Wrapping machines designed to operate with such a wrapping medium are not generally very complex and on the whole offer a smooth flow of product through the wrapping stages.

Certain articles, however, have traditionally always been wrapped in a thin metal foil. Use of such a thin foil wrapper is not only for aesthetic purposes, but also to protect the product and to prolong the shelf life. An example of such a product which is by tradition wrapped in metal foil is the small chocolate covered cake in roll form.

Such fragile products cannot be foil wrapped on a conventional flow wrapping system since the foil cannot be passed over the conventional folding box and heat sealed.

Additionally, this type of wrap would produce an undesirable fish tail finish on each end of the product.

One machine developed to overcome this problem relied upon a carousel arrangement and a complexity of cams and fingers to fold the foil around the sponge roll. This machine, however, proved expensive to manufacture and maintain and was not always consistent in the quality of wrap produced, particularly with products subject to variations in size and shape.

An alternative method of and apparatus for wrapping fragile articles in foil is disclosed in British Patent No.

2108461. According to this disclosure, the articles are passed along a track and the foil wrapper is laid continuously over the articles to pass along the track with them. Both articles and foil are passed beneath a folding plate which forms the foil into a tube surrounding the articles. The articles, encased in the foil tube, are then passed to a twisting and severing station, at which each article to enter the station is rotated about the main axis of the foil tube in order to form a twist in the tube between that and the following article. The foil twist is severed by means of a spring-loaded knife or blade which operates against an anvil. The articles and foil tube are passed continuously through the twisting and severing station so that the foil tube is twisted and severed between each successive article, thereby producing individually wrapped articles.

The main disadvantage of this process lies in its rate of operation. Generally, a machine in accordance with GB2108461 can operate at maximum speeds of only 100 cycles per minute, i.e. 100 twisting and severing actions per minute. Commercially, it would be desirable to be able to wrap articles at a much higher speed than this. Another disadvantage of this method is the need to use a knife and anvil to sever the foil wrapper. Problems of foul-up can arise since the knife has to pass through several layers of twisted foil to the anvil. This in turn leads to difficulties in maintenance of the machine, particularly in cleaning and sharpening of the knife or blade.

It is an object of the present invention to provide a method of and apparatus for the wrapping of fragile articles such as chocolate covered rolls in foil, which is capable of producing wrapped articles at much greater speeds, preferably approaching 400 per minute. The apparatus provided must be simple to assemble and use, preferably constructed from readily available commercial parts where possible, and must be easy to maintain and clean and to clear in the event of "jam-ups". The method should present very few opportunities for fouling-up of the machinery, and all throw-away parts used, such as foam support pads or knives, must be capable of easy and economical replacement.At the same time, none of the advantages of the method and apparatus of GB-2108461 must be lost, namely, the relative simplicity of the machinery and the avoidance of damage to fragile articles.

According to the present invention there is provided a method of. wrapping articles in a foil, in which articles are passed along a track in spaced succession, and in which foil is laid continuously against the articles and the foil being passed against a folding plate which forms the foil into a continuous tube surrounding the articles, the method including the steps of: (a) piercing the foil tube between successive articles; and (b) folding the foil tube between each article and an adja cent point at which the foil tube is pierced, so that the foil tube is severed at the point at which it has been pierced, and so that the foil tube IS folded towa rds the article.

The means by which the articles are fed on to and passed along the track in spaced succession may, for instance, comprise feeding them onto the track by hand at appropriate intervals. Preferably, however, the articles are fed automatically onto the track which then allows for rates of production of wrapped articles not restricted by the maximum rate of hand feeding. Preferably, the track along which the articles are passed comprises a moving conveyor belt and this may have means associated therewith for conveying the articles along in spaced succession.

This means may, for example, comprise dogs carried by an endless chain, which abut the rear end of each article.

The chain of dog teeth may be situated in a longitudinally extending slot running down the centre of the track parallel to the direction of motion of the articles, such that the dog chain may run in the same direction as the articles for at least the first feeding stage of the method of the present invention, in order to assist accurately spaced passage of the articles along the track.

The foil used, which will usually be aluminium foil, is preferably laid over the articles in the form of a continuous sheet which is mounted on a roll above the track. This is preferably passed through a folding plate which forms the foil into a continuous tube as it passes round the articles, the longitudinal edges of the tube slightly overlapping beneath the articles. The exact shape of the foil guiding plate is not critical so long as it produces the necessary contnuous foil tube around the articles. Plates performing this function are already well known and in use in existing foil flow wrapping systems.

The foil tube may be pierced by means of any suitable piercing elements such as thin knives or blades or pins.

Preferably these piercing elements penetrate the foil tube at one or more points along its length and during the period of penetration move along with the foil tube and articles in the same direction and at substantially the same linear velocity.

Preferably, the foil tube is subjected to piercing at four points between each article, by means of piercing elements which enter the foil tube in two diametrically opposed pairs along two mutually perpendicular axes, both of which axes are also perpendicular to the long axis of the foil tube. More preferably, these four piercing elements pierce the foil tube one after the other.

folding of the foil between articles is achieved. by means of folding elements, each of which may comprise a block of dimensions such as to fit snugly between two successive articles. Preferably a small clearance is allowed between, either side of each folding element and the ends of the adjacent articles, for instance about 3 millimetres.

Preferably the folding elements, during the period for which they are in contact with the foil tube, move along with the tube and articles in the same direction and at substantially the same linear velocity. Preferably, the foil tube is folded at'a plurality of points between each article, by means of four folding elements which approach the tube in two diametrically opposed pairs directed along two mutually perpendicular axes, both of which axes are perpendicular to the long axis of the tube. Xore preferably, the four folding elements contact the foil tube one after the other.

In one embodiment of the present invention, the method as described above is characterised by the foil tube being subjected to piercing followed by tucking at a plurality of points between each article, by means of piercing and folding or tucking elements which approach the foil tube in diametrically opposed pairs of piercing elements and diametrically opposed pairs of tucking elements, the piercing and tucking pairs both being directed along mutually perpendicular axes which are perpendicular to the long axis of the foil tube.Preferably, each of the said piercing elements is connected to one of the said tucking elements in such a way as to give four piercing-tucking pairs of which piercing and tucking elements move in unison and approach the foil tube along the same direction, such that when the piercing element of one piercing-tucking pairs enters the foil tube at a point between two successive articles, the tucking element of that same piercing-tucking pair simultaneously contacts the foil tube at a point between two adjacent articles further forward on the track.

The means of connection of the tucking and piercing elements in each pair may comprise, for instance, a simple shaft, such that when one element is driven in a particular motion the second of the two elements is forced to execute the same motion. Alternatively, both piercing and tucking elements may be provided on a-.single supporting arm which is itself driven to perform a particular type of motion.

Preferably this motion allows for the piercing and tucking elements to contact the foil, move along with the foil tube in the same direction and at substantially the same linear velocity for the period of contact and then leave the foil in preparation for the next cycle.

Preferably, the articles passing along the track are supported in some way, more preferably by foam support pads which travel along with the articles at the same speed.

These foam pads would grip the fragile articles lightly and provide a modicum of support as they pass through the piercing and tucking stages of the method of the present invention. They may be provided on one or more endless carrier chains and may be arranged so that each article is gripped by two foam pads, one at each side.

Also provided by the present invention is apparatus for wrapping an article in foil, comprising: (a) a track on which articles may be placed, and caused to slide along; (b) means for forming a sheet of a foil into a cOntinuous tube which surrounds the articles; (c) means for piercing the foil tube 'between adjacent articles; and (d) means by which the foil between adjacent articles may be severed at the point at which the foil tube is pierced, and be folded around an adjacent article.

The conveyor means for moving articles in spaced succession along the slideway may have the form as described above as being in accordance with the method of the present invention. Similarly, the piercing and tucking means may also take the form as described above as being in accordance with the present invention.

Preferably, the piercing and/or folding means comprise piercing and/or folding elements which are driven so as to contact the foil tube at one or more points along its length such that during the period of contact with the foil the said piercing and/or folding elements move along with the foil tube and articles in the same direction and at substantially the same linear velocity.

Preferably, the apparatus cogqrises a set of piercing elements and a set of folding or tucking elements, the elements in each set being arranged in two pairs of diametrically opposed elements directed along two mutually perpendicular axes, both of which axes are perpendicular to the long axis of the foil tube.More preferably, each of the said four piercing elements is connected to one of the said four tucking elements in such a way as to give four piercingtucking pairs of which piercing and tucking elements move in unison and approach the foil tube along the same direction, such that when the piercing element of one piercing-tucking pair enters the foil tube at a point between two successive articles, the tucking element of that same pair simultaneously contacts the foil tube at a point between two adjacent articles further forward on the slideway. The means by which the tucking and piercing elements of a pair are connected may take any of the forms as described above as being in accordance with the method of the present invention.

In one embodiment of the apparatus of the present invention, a plurality of. piercing and tucking elements are provided, arranged in connected piercing-tucking pairs. In this embodiment, the piercing and tucking elements of each pair are both mounted on a single supporting arm which is driven about a point along its length to execute a pistonlike motion, said supporting arm being constrained at a point on its end furthest from the slideway by means of a pivot and slider such that its motion is substantially restricted to being in a direction parallel to the line between the driving point and the pivot, said driving point being itself driven, preferably by means of a planet wheel rotating both freely and around a lain wheel, to execute an elliptical motion wherein the long axis of the ellipse runs parallel to the line between the driving point and the pivot of the said supporting arm. The supporting arm and driving system are mounted such that the piercing and tucking elements are driven -f-irstly towards the foil tube and articles produced by the apparatus of the present invention; move along with the foil tube and articles in the direction of their movement and at substantially the same linear velocity during the period of contact of the said elements with the foil tube; and are then retracted from the foil tube, to return in the next cycle of the movement.

In another arrangement, a piercing-tucking pair may be driven by means of geared drive units, instead of by means of a pivot and slides. Other techniques for driving the piercing-tucking pair with appropriate timing will be apparent.

Preferably, the supporting arm is in the form of a long and narrow isosceles triangle, the short side of which lies substantially parallel to the slideway along which the foil and articles are passed, having the said constraining pivot near to the apex opposite this shortest side, the piercing and tucking elements being mounted on the said shortest side. This supporting arm is preferably driven about a pin located closer to the short side of this triangle than to the pivoted apex.

Preferably the means by which this pin is driven to execute an elliptical motion comprises a first, "planet", wheel to which the pin is attached by means of bearings. This planet wheel rotates about a spindle which itself projects from the surface of a second, outer, wheel. The outer wheel is preferably driven by a constant speed shaft such that rotation of the outer wheel causes rotation of the planet wheel about its perimeter. The planet wheel is driven to rotate about its spindle as it moves around the perimeter of the outer wheel, by means of gears provided in a casing surrounding the outer wheel.

The required motion profile of the piercing and tucking elements in the apparatus of the present invention may be controlled by either mechanical or electronic means.

Electronic control would enhance compactness of the apparatus and increase the ease of cleaning and maintenance. Not only could each piercing-tucking pair be individually controlled by means of programs designed specifically to produce a certain motion profile, but also the possibility of re-programming would become available.

This would be particularly useful for the wrapping of articles of different lengths; the apparatus could be reprogrammed to accomodate the particular length of the article to be wrapped, and would not be restricted in use to one particular article. Possibly the speed at which each article moves relative to the next could be altered in some way at the tucking stage, so as to allow, for instance, for one article to abut the article in front to assist with foil tucking, before the front article speeds up again and separate from the one behind.

It may also be possible to include in the apparatus of the present invention an electronic coding system on the drive associated with the dog chain at the point of entry of the articles. This would ensure that the piercing and tucking elements always moved in synchrony with the dog chain and hence remove the risk of a piercing or tucking element entering an article itself rather than the section of foil tube between two articles.

Naturally in such an electronically controlled system, a microcomputer or other similar processor could be used to a greater or lesser extent to control one or more of the moving parts of the apparatus.

One embodiment of the method and apparatus of the present invention will now be described by way of example only, in terms of a particular apparatus and its method of use, with reference to the accompanying drawings, of which: Figure 1 is a schematic representation of an apparatus for foil wrapping in accordance with the present invention; Figure 2 is a schematic end elevation of part of Figure 1 showing the first stage in the wrapping procedure being carried out by the apparatus of Figure 1; Figure 3 is a schematic representation of the second stage of the method of foil wrapping being carried out by the apparatus of Figure 1; Figure 4 is a schematic section taken along the line A-A of Figure 1 showing the piercing part of the apparatus; Figure 5 is a schematic section taken along line B-B of Figure 1, showing the tucking part of the apparatus;; Figure 6 is a front elevation of a driving mechanism for use in the apparatus shown in Figure 1; Figure 7 illustrates geometrically the arrangement of the piercing and tucking element drive system and the paths described by the moving parts of Figure 6.

Referring firstly to Figure 1, an apparatus for wrapping fragile articles in accordance with the present invention is shown. The articles (1), being chocolate covered sponge rolls or similar products, are fed at (2) on to slideway (3), either manually or preferably by an automatic feeding system positioned to the left of the apparatus shown in Figure 1. The articles (1) pass along slideway (3) in spaced succession, which is achieved by means of dog teeth (4) spaced at a somewhat greater distance apart than the length of one article (1). These dog teeth (4) are carried along an endless chain (5) which is driven by pinion (6).

The slideway (3) has a longitudinally extending slot down its centre in which the dog teeth (4) can travel such that each dog tooth abuts the rear end of one article. The dog chain is driven such that the dog teeth travel along with the articles at the same speed as the articles are required to travel and in the same direction. Each of the dog teeth is pivotally mounted on the chain such that it may be retracted at an appropriate point (7) along the slideway.

A roll (8) of sheet aluminium foil (9), which is appropriately decorated as suits the required:packaging appearance, is mounted above the slideway (3). The continuous foil sheet (9) is tted behind and through the foil forming plate (10) which lays the foil continuously over the articles as they pass along the slideway. Plate (10) forms the foil into a continuous tube around the articles, of which the longtudinal edges slightly overlap beneath the articles by about 0.5 centimetres. As the articles and foil tube continue along the slideway each article is gripped by two foam pads (11), each from above and slightly to one side. These foam pads (11) support the articles and guide them through the rest of the apparatus.

The foam pads are carried along by two endless chains (12), one either side of the slideway (3), driven by pinions (13). Carrier chain (12) is driven at the same speed as that at which the articles (1) pass along the slideway (3).

The articles pass through a piercing stage (14) at which the foil tube is pierced four times by thin knives (15, 16, 17 & 18). These knives are arranged so as to pierce the foil one from below (15), one from each side (16, 17) and one from above (18), in that order. Thus, the foil tube is pierced at four points by knives entering in four directions along two mutually perpendicular axes, both axes being perpendicular to the long axis of the foil tube.

In other arrangements, other arrangements of knives may be used, for example in which the piercing operation takes place first from above, then from each side and then from below.

Having been subjected to these four successive piercing operations, the foil tube passes to the tucking stage, (19). Here the foil is tucked by small block (20, 21, 22, & 23), each of which approaches the foil tube and retracts in turn. The tucking elements approach the foil tube along the same axes as did the four knives. The action of each tucking element pressing into the foil tube at the point at which it has previously been pierced causes the foil tube to tear between the pierces at that point. The tucking element presses the two resultant foil flaps, one on either side of the tucking element, inward towards the ends of the adjacent articles. A clearance of about 3 millimetres is allowed to either side of each tucking element as it enters between two successive articles so as to avoid fouling-up of the tucking element.Despite this clearance the tension of the foil tube around the tucking element as it tears causes the foil to be tucked quite tightly against the ends of the adjacent articles.

The section of foil tube between successive articles has by point (24) in the apparatus been pierced and tucked in four directions and hence completely severed. Thus the articles emerging at (24) are individually wrapped and can be removed frOm! the production line or sent along further conveyor means for packaging.

A lower support chain (25), driven by pinion (26), supports the slideway (3) during the piercing and tucking stages (14 & 19) of the wrapping operation so that the articles (1) continue to move along the slideway at a constant speed.

Figure 2 is a schematic end elevation, viewed from the lett hand side in an upstream direction, of part of Figure 1 showing the foil forming plate (10) and an article (1) approaching the plate (10) from behind. Article (1) sits above the longitudinal slot (27) in slideway (3) and is conveyed by chain dog (4) through the foil forming plate (10). Sheet foil is passed downwards and tbrough plate (10) in the direction (28), and is formed into a continuous tube around the articles passing through plate (10).

Figure 3 is a similar end elevation of Figure 1 to that shown in Figure 2. An article (1) has passed through and beyond foil forming plate (102--and is now surrounded by a continuous foil tube. Two foam pads (11) move in to grip the article (1) from either side as the article is carried further along the slideway (3)-on to the lower support chain (25). The foam pads (11) are mounted on supports (29) on the carrier chains (12) so as to be easily replaceable after a period of use.

Figure 4 is a section taken along the line A-A of Figure 1 which represents schematically the piercing stage (14) of the foil wrapping process being carried out in Figure 1. The article (1) is passed further along the slideway (3) still supported by foam pads (11) and lower support chain (25). Knives (15, 16, 17 & 18) approach the foil tube surrounding the articles along orthogonal axes as shown. The knives penetrate the foil tube at four points between two adjacent articles. Each knife executes a motion such as to penetrate the foil, move along with the foil tube and articles for a short period in the same direction and with substantially the same speed as they are moving, and finally retract from the foil tube. This motion enables a "clean" cut to be made without tearing of the foil tube.

The four knives execute this motion one after the other in succession.

Figure 5 is a schematic section taken along the line B B of Figure 1, showing the tucking stage (19) of.the foil wrapping method depicted. Pour tucking elements (blocks 20, 21, 22 & 23) press into the foil tube between successive articles at the points which have previously been pierced. Each of the tucking elements is paired to one of the knives (20 to 15, 21 to 16, 22 to 17 and 23 to 18) such that each tucking element approaches the foil tube in the same direction and execute the same motion as its partner knife. Again the tucking elements press into the foil tube one after the other in succession.

Figure 6 is a schematic representation of a driving mechanism for driving the motion of each piercing-tucking pairs. In this arrangement, the supporting arm (42) takes the form of a long and narrow isosceles triangle of which the shortest side (43) lies parallel to slideway (3) in the apparatus of Figure 1. The supported piercing-tucking pair consists of knife (44) and tucking block (45), supported one at either end of the short side (43). At the apex of arm (42) opposite to (43), the arm is again constrained by means of pivot (39) in slider (40) as before. Again as before, the supporting arm (42) is mounted on a planet wheel (35) by means of pin (36).The planet wheel (35) rotates both freely and also around the perimeter of outer wheel (30) such that pin (36) executes an elliptical motion and again the motion profile of the knife (44) and tucking element (45) is as required.

Figure 7 shows schematically the motion executed by the pin (36) of Figure 6. Circle (46) represents the gear (53) set in the outer casing (31), which in this case has a diameter of 170 millimetres. Circle (47) represents the initial position of planet wheel (35) and (48) its position after the outer wheel (30) has completed a 900 rotation in the clockwise direction. Planet wheel (35), of diameter 85 millimetres, clockwise direction and hence pin (36) has completed a 900 rotation in the anti-clockwise direction by the time position-(48) is reached. The locus of points traced by the position of pin (36) during one complete revolution is give by an ellipse (49).

Arrow (50) shows the relative direction of. travel of each article being wrapped, and the figure clearly shows that for the period for which a piercing or tucking element supported on an arm (38 or 42) supported by pin (36) is in contact with the foil tube, the linear velocity of that element in the direction of travel of the article to be wrapped is substantially constant. The piercing or tucking element travels with the foil tube for a direction of 27 millimetres and its maximum penetration is shown to be 29 millimetres. Point (51) represents the end of a knife or a tucker element. Line (52) represents the long axis of the arm (38 or err2) on which piercing and tucking elements are supported, and meets pivot (39) and slider (40) directly below the centre of outer wheel (30).

Claims (12)

1. A method of wrapping,articles in a foil, in which articles are passed along a track in spaced succession, and in which foil is laid continuously against the articles so as to pass along the track therewith, the articles and the foil being passed against a folding plate which forms the foil into a continuous tube surrounding the articles, the method including the steps of: (a) piercing the foil tube between successive articles; and (b) folding the foil tube between each article and an adjacent point at which the foil tube is pierced, so that the foil tube is severed at the point at which it has been pierced, and so that the foil tube is folded towards the article.

2. A method as claimed in claim 1, in which the foil tube is pierced at more than one point around the periphery thereof.

3. A method as claimed in claim 2, in which the points at which the foil tube is pierced are in a single plane which extends perpendicular to the axis of the tube.

4. A method as claimed in any one of the preceding claims, in which the foil tube is pierced by means of a piercing element which moves along the track at approximately the same speed as the foil tube.

5. A method as claimed in any one of claims 2 to 4, in which more than one piercing element is used to pierce the foil tube, and in which the piercing elements pierce the tube in succession.

6. A method as claimed in any one of claims 1 to 5, in which the portions of the foiL--tube between an article and the point at which the tube is pierced is folded by means of folding elements which contact the foil tube, and which move relative to the track together with the foil tube.

7. A method as claimed in claim 6, in which a plurality of folding elements are provided spaced aparat around the periphery of the foil tube, the folding elements contacting the foil tube successively around the periphery thereof.

8. A method as claimed in any one of claims 1 to 7, in which a piercing element and a folding element approach the foil tube simultaneously, the piercing element piercing the tube, and the folding element contacting the tube at a point between an article and the point at which the tube is pierced so as to sever the tube at the pointat which it is pierced and to fold the tube around the article.

9. A method of wrapping an article in foil, substantially as hereinbefore described with reference to any one of the accompanying drawings.

10. Apparatus for wrapping an article in foil, comprising: (a) a track on which articles may be placed, and caused to slide along: (b) means for forming a sheet of a foil into a continuous tube which surrounds the articles; (c) means for piercing the foil tube between adjacent articles; and (d) means by which the foil between adjacent articles may be severed at the point at which the foil tube is pierced, and be folded around an adjacent article.

11. Apparatus for wrapping an article in foil, by means of a method as claimed in any one of claims 1 to 9.

12. Apparatus for wrapping an article in foil, substantially as hereinbefore described with reference to any one of the accompanying drawings.