Abstract:
A packaging machine is described for forming, filling and sealing bags with a product. The machine forms a film into an elongate, side-sealed tube as it travels in a first direction, and severs the elongate tube into individual, open-ended, bag-length elements. These are then transported in a second direction transverse to the first direction, and a bottom seal formed on them to convert them into open-topped bags. A carousel is arranged to receive the open-topped bags. Product is introduced into each of the open-topped bags, and a top seal formed on each of them to convert them into filled, sealed bags, as the bags travel round the carousel.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a packaging machine and, more particularly, to a machine for packaging snack products (e.g. potato crisps) and other low density materials. A typical use would be to package 30 g portions of crisps in bags 127 mm wide and 178 mm long. 
     2. Discussion of the Related Art 
     There is a limit to the speed at which a conventional vertical, form, fill and seal machine can package snacks and other lightweight products. The speed is limited by the maximum rate at which the product can fall and the length of time needed to heat seal the film. 
     SUMMARY OF THE INVENTION 
     The present invention uses a method in which the packs preferably travel round on a carousel. Hence much more time is available for the processes involved in forming and filling the bag and the machine operations are less interdependent. 
     Filling by means of a rotating carousel is already widely used with rigid containers such as in the canning industry, and to a lesser extent with flexible packaging. 
     Two particular instances of machines which have carousels for the filling of flexible packaging are: 
     a) A machine produced by Jones &amp; Co. Inc. of Cincinnati, Ohio 45201, USA. In this machine, a reel of flat film is folded longitudinally and then divided into sections by sealing. The pouches so formed have three closed edges and are still joined to one another. The string of pouches passes round a carousel, where product is introduced from a number of chutes. The top seal is then made and the pouches are cut from each other. This type of filling is suited to heavier products such as soups, rice or confectionery, and is in use elsewhere. 
     b) A machine produced by Thurlings Verpackungsmaschinen GmbH, of D-41749 Viersen, Germany. With this machine, the film is made into bags by conventional vertical, form, fill and seal means (film unwind, tubeformer, vertical seal and jaws). Only one end of each bag is sealed and the open bags already separated from one another, are then transferred to a rotating turret by means of vacuum operating suckers. The turret has a number of stations, each with a number of fingers, which project into each bag and open to hold it in position. The turret indexes round and product is introduced by a chute. After the bag has left the carousel, its top seal is made. 
     According to a first aspect of the present invention there is provided a packaging machine for forming, filling and sealing bags with a product, which comprises means for forming a film into an elongate, side-sealed tube as it travels in a first direction, means for severing the elongate tube into individual, open-ended, bag-length elements, means for transporting the said elements in a second direction transverse to the first direction, means for forming a bottom seal on said elements to convert them into open-topped bags, a carousel arranged to carry the open-topped bags, and means for introducing product into each of the open-topped bags and for forming a top seal on each of the bags to convert them into filled, sealed bags, as the bags travel round the carousel. 
     According to another aspect of the invention there is provided a machine for forming a film of heat-sealable film into an elongate, side-sealed tube, comprising a tubeformer for forming the film into shape of a tube with overlapping longitudinal edge portions as it travels from a film supply, inner and outer pressure members which engage the inside and outside of the said edge portions and travel with them, and means for applying heat to the said edge portions. 
     According to a further aspect of the invention there is provided a device for use in filling open-topped bags with a product, comprising fingers adapted to enter and hold the open top of each bag, and a chute formed of a plurality of members which are movable with respect to one another from a configuration in which the chute can enter the open bag top to an expanded configuration in which product can enter the bag therethrough. 
     Other aspects of the invention appear from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention will now be described with reference to the accompanying drawings, in which: 
     FIG. 1 shows the general arrangement, in diagrammatic form, of an embodiment of a machine according to the invention; 
     FIG. 2 shows the complete vertical seal assembly used in the machine of FIG. 1; 
     FIG. 3 shows a picker for the use in the machine. The embodiment of picker shown in FIG. 3 differs from that shown diagrammatically in FIG. 1; 
     FIGS. 4 a  and  4   b  are a plan view and an elevational view (partly sectional) showing in detail a bottom sealer for use in the machine, the design being similar to the top sealer, the sealer being shown only diagrammatically in FIG. 1; 
     FIG. 5 shows a cup and finger mechanism, with the cup in its open position; 
     FIG. 5 a  shows a detail of FIG. 5, with the cup in its closed position; 
     FIG. 6 is a perspective view of a modified form of pinch rollers; 
     FIG. 7 is an exploded perspective view of a preferred design of knife; 
     FIG. 8 is a perspective view of a modified form of picker mechanism, incorporating transit belts upstream of the picker belts; and 
     FIGS. 9 to  18  show a modified form of the assembly of cup, fingers and arm carrying the cup and fingers, in which FIG. 9 is a perspective view with the fingers and cup both open, FIG. 10 is a similar view, but with the fingers omitted and the cup closed, FIGS. 11 and 12 are side elevations of the assembly from opposite sides, FIG. 13 is a partly exploded perspective view showing individual components, FIG. 14 is a more completely exploded view, FIG. 15 is a perspective view showing the operation of the fingers, and FIGS. 16 to  18  show the finger mechanism with the fingers respectively open, closing, and closed, some of the components not relevant to the movement of the fingers being omitted from FIGS. 16 to  18 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The machine shown in FIGS. 1 to  5   a  of the drawings will firstly be described in more detail, referring to the various sections of which it can be regarded as being composed: 
     a) Film Handling Mechanisms 
     The initial film handling mechanisms use techniques already employed with existing vertical, form, fill and seal machines. A reel of film  1  is supported on a horizontal axis by a mandrel (not shown), and means (not shown) are provided to unwind it and brake it as necessary. Adjustment of the lateral position of the reel is required so it can be tracked to be in line with the tubeformer. Date code printing and registration detection, i.e. detection of registration markings which denote the end of each bag and with which the film is pre-printed, take place (this can be by conventional means) and the film then passes through a tubeformer  2 . 
     b) Tubeformer 
     A conventional tubeformer is used, as applied to current vertical, form, fill and seal machines, to make the film  1  into a tube  3  with overlapping edges  4 . FIG. 2 shows a frame  5  which is used to support the tubeformer, and indicates as  6  the location where the tubeformer is mounted. FIG. 2 omits the tubeformer itself. 
     c) Vertical Sealer and Film Pull Down 
     Within this film tube  3  is a moving inner belt  7 , which contacts the film where its edges overlap. Outside the tube, also at the point where the two edges of film overlap, is an outer moving belt  8 , which contacts the film, and a heating block (not shown). Hence both internal and external film contacting surfaces are running at film speed while heat is transmitted to the film to make the longitudinal seal. Since in the embodiment illustrated in FIG. 1 the tube of film moves vertically downwards, this is referred to here as the vertical seal, though it must be understood that other orientations of the tube are possible. It is also to be understood that the illustrated sealer may be replaced by one having stationary sealing elements, for example one in which there is a stationary internal heater and stationary external heater. 
     Immediately at the bottom of the vertical seal belts  7 ,  8  are a pair of spreading fingers  10  (see FIG. 2) which are inside the round film and serve to flatten it. Beneath this is a pair of pinch rollers  11  which pull the film from the reel, over the tubeformer and through the vertical sealer. In the view of FIG. 2 one of the pair of pinch rollers is visible, and it can be seen to consist of two roller elements  11   a,    11   b  each attached to one of the spreading fingers  10 . The distance between the two elements is adjustable, so as to enable the distance between the spreading fingers to be adjusted, and this allows for films of different widths. FIG. 2 also shows drive belts  12  and  13  for driving the sealing belts and pinch rollers respectively from a motor  14 . The belt  13  passes over a roller  15  offset outwardly to maintain tension in the belt. 
     d) Knife 
     A knife (see FIG. 2 for the location  16  of the knife), an embodiment of the knife being described below with reference to FIG. 7, cuts the film, which is now a flat tube, into bag length sections. A rotary knife rotating about a horizontal axis is preferably used, its speed being matched to the film speed. The motions of the vertical seal, pull down rollers and knife are synchronised to the registration marks on the film, so that bag sections cut to the right length are presented to the next handling mechanism, at exactly the right time. 
     e) Picker 
     The bag section must remain under control immediately after it is cut and so a pair of opposed vertically moving retaining belts  17  (see FIG.  2 ), driven via a drive belt  18 , support it lightly. The transition from the vertical motion to the horizontal motion, necessary for presentation to the carousel, is performed by a picker  20  (see FIG.  3 ). This consists of a plurality of pairs of parallel horizontally moving belts  21  (three such pairs are shown) with protrusions  22  which grip the bag sections, the righthand edges of which travel down a guide plate  23 , and cause them to move horizontally. The motion of these belts is such that each bag section is quickly released from the vertical retaining belts  17  and its speed is matched to the carousel when it is presented to it. The belts  21  pass round a first set of pulleys  24  on a first pair of shafts  25 , driven by a motor  25   a , and a second set of pulleys  26  mounted on a second pair of shafts  27 . The second shafts  27  are driven by a motor  27   a  and the pulleys  26  are fixedly secured thereto. The pulleys  24  are mounted for freewheeling motion on the shafts  25 , which is necessary because the shafts  25  also carry additional further pulleys fixedly secured thereto (not shown in FIG. 3) whose function is explained below and which need to be able to travel at a different speed to the pulleys  24 . 
     f) Bottom Sealer 
     The technology used to form a bottom seal on each of the bag sections is well known within the industry as applied to fin sealing. As shown in FIGS. 4 a  and  4   b , the bottom sealer  30  comprises a pair of disc shaped, heated rollers  31 ,  32  which rotate in a horizontal plane and pinch the film between them. The pinching effect is achieved by having one of the rollers (the righthand one  32  in FIGS. 4 a  and  4   b ) spring-loaded towards the other by washer-type springs  40 , for example Belleville washers, which are inserted on the proximal side of locknuts  41  threadedly received on rods  42  which hold roller mountings  43  together. The other roller,  31 , has a timing belt  33  mounted thereon to transmit drive thereto from a motor  44 . The bag is transported by means of a pair of lower belts  34 ,  35  each of which passes around a respective pair of pulleys  36 ,  37  and which are located immediately above the sealing rollers, and by another pair of belts  38 ,  39  (see FIG. 3) which retain the top of the bag. 
     g) Bag Opener 
     The bag opener  50  can be seen in FIG.  3 . Immediately after the bottom sealer  30 , the open-topped bag thus formed continues to be retained by the lower belts  34 ,  35 . The upper belts  38 ,  39  come apart gradually. These belts have a row of holes  51  spaced along their length. A slight vacuum is drawn from behind them by vacuum chambers  52  to which vacuum is supplied from a vacuum source (not shown) via a duct  53  and so the top of the bag opens. 
     h) Carousel 
     The carousel  60  and components thereof are shown in FIGS. 1 and 5. It consists of a rotating hub (not shown) with a number of radial arms  61  fixed to it. These arms hinge vertically about hinge points  62  so that the mechanisms on their outer ends can be inserted into the bags. Each mechanism comprises a pair of fingers  64  and a cup  65 . The fingers enter the bag and hold the bag longitudinally (tangential to the carousel) so that the top of it is kept under control as it is released from the opener. The cup  65  comprises an inner cup half  65   a  and an outer cup half  65   b  which are movable radially with respect to one another between an open position (FIG. 5) and a closed position (FIG. 5 a ). After these have been inserted into the bag with the cup in the closed position of FIG. 5 a , they are separated radially, into the position in FIG. 5, so that they form a chute at the top of the bag into which the product can be dropped. The fingers  64  are sprung loaded so they come together as the cup halves open. 
     The way in which movement of the cup halves, the cup as a whole, and the fingers, is achieved, can be understood from FIGS. 5 and 5 a . The inner cup half  65   a  is connected, by means shown only in part, to a cam follower  66 , and the outer cup half  65   b  is connected by rods  63  and a yoke  67  to a cam follower  68 . Each of cams  66  and  68  is adapted to engage a respective stationary cam as the arms rotate about the carousel. The cup as a whole, with its arm  61 , is pivoted upwards and downwards about the pivot point  62  by means of a cam follower  69  which engages a further stationary cam  70 . Movement of the fingers  64  towards and away from one another is controlled by a rod  64   a , the radially inner end of which is arranged to contact a stationary disc  64   b  and the radially outer end of which is connected to a pivot arm assembly  64   c  which carries the fingers  64 . 
     i) Bag Transport Round the Carousel 
     After the bag has left the bottom sealer and the opener, the top of it is retained by the fingers and cups. The bottom of the bag is retained by a pair of horizontally moving opposed belts or belt arrays (not shown), similar to those used for letter transporters in automatic sorting systems. The two belts or belt arrays follow concentric circular paths and carry the bottom of the bag between them. 
     j) Product drop 
     Product is dropped from a conventional multihead weigher (not shown) with a fixed chute at its lower outfeed end. As the carousel rotates, the bags with their open chutes pass under the fixed weigher chute. The dropping of the product is synchronised to the passage of the bags underneath. 
     k) Stripping 
     Immediately after it has been discharged, the product may have a tendency to project above the top of the bag into the cup area. In the first instance, the product will be compacted by jostling the bag as it proceeds round the carousel. Finally, a plunger (not shown) may be used to force any remaining product below the level where the top seal is formed. 
     Top Sealer 
     Immediately before the top sealer  9 , which can be of conventional construction, the cup halves are partially closed and the fingers and cup are withdrawn from the bag. The top of the bag is retained by belts as it is introduced to the top sealer, which operates on the same principle as the bottom sealer. After this the bag is discharged from the machine. 
     FIG. 6 shows a modified design for the pinch rollers, replacing the rollers  11 . Each of the rollers  71  shown therein comprises a pair of outwardly extending land sections  72 ,  73  which run axially between locations A and B, and C and D, respectively. The axial distance between A and D is less than the width of a bag, typically 20 mm less, so that the tube of film is not compressed at its edges and is therefore not creased. This is desirable both operationally and from the point of view of appearance. The recess BC defined between the lands is broader than the vertical seal, so that the film does not contact the pinch rollers in this area, which at the stage when the film passes between the pinch rollers, is still hot. This minimises the risk of the front and rear parts of the film being caused to adhere to one another. 
     FIG. 7 shows a preferred construction of knife  90  for installation at location  16  (see FIG.  2 ). This is a crush knife and comprises a pair of cylinders  91  and  92  mounted for synchronous rotation in opposite senses in end blocks  93 ,  94 . The cylinder  91  has an anvil  95  the surface of which protrudes slightly from the remainder of the cylinder surface and which extends along the length of the cylinder. The cylinder  92  has a cutting member  96 , the cutting edge  97  of which runs at a small acute angle α to the axis of rotation of the cylinder  92 . This angle α may, for example, be from 1° to 2°, and in an actual embodiment an angle of 1.3° was found to be suitable. The cylinder  92  is arranged so that its axis of rotation is at an angle of (90+α)° to the path of the film, as indicated in FIG. 7, so that the cutting edge  97  is at 90° to the film path. The cylinder  91  has its axis of rotation parallel to that of cylinder  92 . 
     In use, the cutting member exerts a cutting force on the film at only a single point (more precisely, a single very small region) at any one moment in time, and this point or region travels rapidly across the width of the film as the cylinder rotates. This gives a very high cutting force and a correspondingly effective cutting action. 
     FIG. 8 shows a modified picker mechanism, in which to the picker  20  shown in FIG. 3 has been added a transit assembly  80 . This comprises guide rollers  81  which are situated immediately below the knife and which run at the same linear speed as the pinch rollers. The film, a portion of which is denoted in FIG. 8 by numeral  82 , is held simultaneously by the guide rollers and the pinch rollers while it is being cut by the knife. Immediately below the guide rollers  81  are two pairs of transit belts  83  which are driven at a higher linear speed than the guide rollers  81  by a motor  84 , pulleys  85  and a drive belt  86 . The guide rollers can, if desired, be fitted with roller clutches so that they run faster than their driven speed when the bag is being pulled by the transit belts. Since the transit belts are running faster than the vertical speed of the bags as they are cut, a vertical gap is generated between successive bags, so that they can be removed horizontally by the picker without interfering with one another. 
     The modified arm assembly shown in FIGS. 9 to  18  will now be described. This comprises an arm  100  pivotal about a horizontal axis passing through a pivot point  101 . The arm is L-shaped, with a generally vertical portion  100   a  which carries an arm-lifting cam follower  102  at its lower end, and a generally horizontal portion  100   b . The cam follower  102  is arranged to engage, over a given segment of the rotation of the assembly, a lift cam  103  (see FIG.  17 ). A double-armed lever  104  is pivotally connected to the arm  100  intermediate the ends of the arm. The upper end of lever  104  is connected by a pair of pivotal links  105  to an upstanding portion of a cross-member  106  which, together with a pair of parallel rods  107  forms a first yoke  108 . An inner cup half  109  is fixedly connected to the distal end of the rods  107 . The lower end of lever  104  is connected by a pair of pivotal links  110  to a downwardly projecting portion of a cross-member  112  which, together with a pair of parallel rods  113  form a second yoke  114 . An outer cup half  115  is fixedly connected to the distal ends of the rods  113 . 
     The arm  100  has a guide plate  116  at its radially outer end. This has a pair of openings  117  through which the rods  107  pass in slidable fashion, and a pair of openings  118  through which the rods  113  pass in slidable fashion. A shaft  119  is secured to the cross-member  112  and extends from it in a direction away from cup-half  115 . The shaft  119  carries a cup-controlling cam follower  120  on its underside which is engageable by a cup cam  121 . The cam follower  120  is biassed in a radially inward direction towards the cup cam  121  by a compression spring  122  (see FIGS.  11  and  14 ). 
     Referring particularly to FIG. 15, the arm assembly has a pair of fingers  125  each of which extends radially outward from a block  126  on the underside of a respective crank arm  127 . At its inner end each crank arm carries an upstanding pin  128 , and at its opposite end each crank arm carries beneath it a cam follower  129 . Intermediate its ends, each crank arm has a pivot pin  130  by means of which the crank arms are mounted, for pivotal movement about generally vertical axes, between projections  131  extending from the guide plate  116  (see FIG.  13 ). A member  132 , referred to herein as a load cam, is mounted on a downwardly extending pin  132   a  (the upper end of the pin is visible in FIG.  15 ), received in an opening  132   b  in the upper surface of arm portion  100   b  (see FIG.  13 ), for pivotal movement about a generally vertical axis. A lug  133  extends from the radially outer edge of the load cam  132  and is positioned to be engaged by one arm of an L-shaped trigger  134  which is pivotally connected to the block  126  for movement about a generally horizontal axis. FIG. 15 also shows a striker post  135  which is fixedly mounted on the frame of the carousel (i.e. it does not rotate with the carousel) and which is arranged so that in one position of the arm in its rotation with the carousel, for which see below, the lower arm of the L-shaped trigger  134  strikes it. 
     The upper ends of the pins  128  are held in a slot  136  formed in the underside of a plunger  137  which is spring biassed in a radially outward direction by a compression spring  138  whose other end bears against the cross-member  106  (see, for example, FIG.  9 ). It should be noted that when the cup is open the distance between the cross-member  106  and the plunger  137  is much greater than when the cup is closed. The size of the spring, and its spring constant are chosen so that in the former condition it exerts very little force on the plunger, whereas in the latter condition it exerts a substantial force. This means that when the cup is open the fingers are urged apart only lightly and are not able to open the bag sideways and thus flatten it. This is clearly advantageous, in that the object of the open cup is to enable product to be introduced into the bag. A resetting rod  139  is connected at its radially outer end by a ball joint to the load cam  132  and is slidably guided adjacent its other end by a guide member  140  connected to the arm  100  for pivotal movement about a horizontal axis with respect thereto. The radially inner end  141  of the resetting rod is arranged to bear over a given segment of the rotation of the assembly against a cam disc  142  (see FIG.  17 ). 
     A description will now be given of the operation of the assembly of FIGS. 9 to  18 , in relation to its rotation with the carousel through 360°. The sequence of events which takes place is as follows (it must be understood that the angles are approximate, and can vary substantially from machine to machine): 
     0°: The arm  101 , which is at an intermediate height, starts to drop into the bag which is being held open by the vacuum belts, the fingers being closed as shown in FIG.  18 . Lowering of the arm is under the control of engagement between the cam  103  and the cam follower  102 . The cup is in a closed condition. 
     5°: Continued lowering of the arm causes the trigger  134  to strike the post  135  (see FIG. 15, where contact has just been made), which then causes the trigger to rotate. This in turn produces rotation of the load cam  132 , via its lug  133 . The load cam is no longer in a position to keep the cam followers  129  apart, and the crank arms  127  therefore rotate under the force applied to their pins  128  by the spring  138 , so moving the fingers  125  to their open position (FIG.  16 ). Shortly after this position the arm becomes fully lowered (horizontal). 
     10°: The cup-controlling cam follower  120  engages the cam  121  (FIG. 10) and starts to move the outer cup half  115  radially outwardly. By virtue of the double-armed lever  104 , the inner cup half  109  simultaneously starts to move radially inwardly. Thus, the cup begins to open. 
     20°: The cup is now fully open (FIG.  9 ). 
     45°-90°: Product is introduced into the bag through the open cup as the arm rotates through this range. 
     180°: The radius of the cam  121  begins to reduce, causing the outer cup half  115  to begin to move radially inwards, and, by virtue of the double armed lever  104 , causing the inner cup half  109  simultaneously to begin to move radially outwards. Thus, the cup begins to close. 
     200°: The cup is fully closed and the bag is held by the fingers. The arm starts to lift as a result of re-engagement of the cam follower  102  with the cam  103 . 
     230°: The arm reaches an intermediate height, ready to transfer the bags to the top seal belts. 
     250°: The fingers are reset to their closed position by engagement of the resetting rod  139  with the cam disc  142  (FIG.  17 ). 
     270°: The arm reaches its maximum height to clear the top seal mechanism. 
     315°: The arm starts to drop down. 
     360°: As 0°.