IE39067L - Forming packages - Google Patents

Abstract

1438952 Packaging machines F D C BATE 7 March 1974 [15 March 1973] 12542/73 Heading B8C [Also in Division B5] The drawings and description relate to the apparatus disclosed in Specification 1,438,951 in every detail. Claim 1 is directed to the method of forming a package including the steps of continuously feeding two superposed layers of wrapping film through a sealing station, selecting the stroke length of a sealing device, reciprocable along the path of the films, to synchronize the speeds of the device and films, and lowering the sealing device to join the films with a seal transverse to their path. Claim 9 relates to the sealing mechanism. [GB1438952A]

Description

39067 In the packaging industry it io aometimes required to form tubes or.envelopes by causing two overlying layers of sheet notorial to adhere to each other at spaced-apart regions, louving an opcn>endod tube (ono or both ends of which may bo subooquontly soalcd) batweon tho two opucod-opurt odhoring regions. *'or exaaplo, bugs of p.-ipor or plastics film can be produced by feeding long lengths of two layers of the paper or film through a soaling station and causing the layers to adhere to each other in longitudinally spaced transversa bands. Thi3 produces a continuous uerie3 of tubes to receive the articles to be wrapped. It is also possible to sever the paper or film along each adhering band, so that the tubes become separated from each other.

In thu shrink-wrapping cr goods on the othor hand, it is not usual to prepare bags or tubas and then to insert tho article to be wrapped into t)-.? bag or tube. Instead, two sources of film ore used, and the "free" ends of the two films are sealed together so that there is formed a barrier of film extending vertically between the two supply sources (usually reels). An article to be wrapped - and the expression "article" will be used herein to include a collection of articles which are to be wrapped together is then traversed in a direction at right angles to und passing through the film barrier. As a result, film is drawn off the supply sources-ana the film becomes wrapped first over tao loading siuc* of the article, and then over the top and bottom of thu article. The two films are then brought together on the trailing side of the article and sovercu on a transverse line and simultaneously sealed together -on both sides of the line of cut. The article 39067 is then wrupped in a tube of fila which is open at both ends, and u frooh barrier of fila is creuted ready to ruceivo the nuxt article. The fila is considerably wider than the urticle, and hence the tube ovorhangs tho articlo at both onus. Those overhanging parts of tho tube cun be gathored and cooled together so that the article is totally enclosed' ready for the heat-shrinking of the fila wrapping* or the overlapping parts of the fila can siaply be allowed to contract on to the ends of tho article if total enclosure by the wrapping fila is not uuuontial.

Thus it will be uppruci.->ted thnt thero have been two distinct types of puckui*ing, one which involves the fornation of packets into which the article to be wrapped ia fed, and tho other involving the wrapping of the fila around the article to produce the packa^c.

In Pftteat Specification Ho. 38024 there is described a method of foraing a package for an article comprising the steps of feeding two layers of wrapping fila in close juxtaposition with each other along aligned paths of truvel in the suao direction; causing an udherent relationship between the two layers of fila at transversely extending positions 3paced apart relatively to the direction of feed; severing the fila on transverse lines of cut at each adherent region so that a flat tube of film is produced, which is detachoa from a preceding similar tube and from the tube being fod to tho tube-forming position; opening out the Xlat tube so j .1m/i 4 mba • m/v ua u /» 1 a v* ljwt nnah { 1U11BWU| TM f**- WAM7A& k M -|T * MII U* W*%*« WV open tube. 39067 III Patent Specification No. 38025 which id divided out of Application So: $0399/72 (serial No: 1,^2#,951)> there iu daccribodunothod of wrupping an article comprising tho steps of feeding the article along a translator? path; forming a trubo of wrapping material and moving it alongside the translator? path, with at least tho end of the tube nearest to the article open; providing an inserted oxpansible tubo-opening device in u collapucd condition, in at least the opon end of the tube; moving tho tubo^opening device along the translator? path with the article; expanding the tube-opening device to open out at leost the opon end of the tube, and feeding the article laterally of the trunslatory path to feed it into the tube whilst the tube and the articlo move along the path.

The present invention i3 concerned with a method and apparatus for forcing packaging tubes, and the invention is capable of applications eithor to the manufacture of bags or the provision of a wrap for a shriuk-wrapping process.

According to the invention a method of forming a package includes the steps of continuously feeding two superposed layers of wrapping film through a sealing station at a preselected velocity; selecting the cycle frequency of a sealing device reciprocable along a path parallel to that of the film feed, to determine the distance between transverse seals formed by tho sealing device on the two layers of wrapping film, simultaneously selecting the cycle frequency of a film severing device to coinciae with the frequency of the sealing device; selecting the stroke length of the sealing device so that it travels on its forward stroke in the same direction as the layers of film at the same linear speed as the film; bringing the sealing device into operative relationship with the layers of film during at least part of its forward stroke in each cyclc to produce a sealing together of the two film layers transversely to the direction of the film feed, - 4 - 39067 and operating the severing device ainultaneoualy with the formation of the tronovoruo suul, to covor tho fila layoro uloag a line oxtending aoroaa the width of the fila layers and within the width of a aeul formed by the soaling device to uopufat'o u fila jmciuigo in advunco of the line of aover froa the following fila.

According to a preferred feature of the invention the sealing device has a compound movement in ita forward traverse, including a movement perpendicular to and towards the path of the fila feed, but is maintained in a constant oriontation relatively.to the path of the fila throughout the reciprocating cycle of the sealing device* i*referably the fila layera are severed along a transverse line bounded on both sides by one of the transverse seals, to form separate fila tubea along transverse edges but open at the longitudinal edges.

According to the invention a sealing mechanism for sealing together two lnvers of wrapping fila at longitudinally spaced apart positions compriaos traversing aeons for traversing the two lcy?rs of film in a forward direction along a predetermined path; the traversing means including a conveyor moving continuously in one direction and articulatod holding means for nipping the two layers of fila on to tho conveyor; a mechanism for reciprocating the holding means along a path parallel to the predetermined path and a driving mechanism for both the convoyor and the holding means, this driving mechanism including a variable device for varying the cycle frequency of the reciprocuble holding moans relatively to the linear apeed of the film; a sealing and severing device carried by the holding means and mechanism for bringing the sealing device into operative relationship with the film layers during at least part of the forward motion of the holding means. Proferably the length of the stroke of the 39067 holding means is adjustable. In one fore of the invention the means for causing rociprocation of the holding aeons comprises an oscillating motion transmitter of variable stroko length. 5 According to another preferred feature of the invention, driving means for the articulated part of the holding meuns includes a cam adapted to be rotated at an angular velocity directly rtUt«d to the linear speed of the conveyor element. Preferably there is also a cam driven mechanism adapted to bo 10 operated in •ynchronicB with the conveyor element, and further adapted to cause movement of the sealing device towurds the conveyor element, during that part of the cycle of the holding means, when the sealing device i3 required to carry out its sealing function. 15 It is also preferred that the holding means is adapted to remain in u constant orientation relatively to the path of movement of the layers of fila.

According to another preferred feature of the invention the holding means comprises a carriage having a pair of 20 rollers for engagement with the film. Preferably the rollers aro onch ncsred to an endless chain driven at a linear speed directly related to that of the conveyor element, the gear ratio providing that on forward movement of the carriage there is no rotation of each roller about its own axis. 25 According to a still further preferred feature of the invention, at least one roller of the carriage is adapted to be given a sudden rotation at the end of the forward movement of the carriage, for the purpose of pulling a tube of film away from the following bulk of film. - 6 - 3 9 0 G ? Other preferred features of tho invention will appjar from tin? following description of q specific embodiment of the invention which is described by way of example only. The nschine here described is also described in the Patent 5 Specification No. 38024.

In tho accompanying drawings:-SPECIFIC iJlBODm^NT.

A machine for producing packs, which is constructed and adapted to operate in accordance with the invention and 10 its method of operation will now be described^, by way of example only, with reference to the accompanying drawings, in which Figure 1 is i perspective view nhowinir the feneral layout of the machine, 15 Figure 2 is a diagraumatic elevation of t\ basic conveyor arrangement, Figure 3 is a diagrams.* tic plan view of the machine, showing packages being formed on the machine, Figure 4 is a perspective view of a film feed convcyor, 20 Figure 5 is a detailed end view partly in section, and to a larger scale showing part of the film feed conveyor, Figure 6 is a plan view of the film feed conveyor showing tho formation of whereon, Figure 7 is a pcrspec.i-i.vc view of a scaler head 25 operating mechanism, Figuro 8 is a perspective view to n larger scale of part of the sealer head operating mechanism, Figuro 9 is a perspective view of a carriage, part of which is also shown in Figure ?, 50 Figure 10 is a side vic-w to a larger scale of a flicking mechanism shown in Figure 9, - 7 - 39067 Picurv 11 is a detail perspective view of part of an indicator, Fip;uru 12 is a front view partly in section of a sealer head* Figure 13 ia a section on thu line XIII-XIII in Figure 12 showing the sealer head in detail, Figure 14 is a suction on tha line HV-XIV of Figure 7 showing another part of the sealer head operating mechanism, Figure 15 is an end view of a product carrier shown in a retracted position, Figure 16 is a view looking in the direction of arrow ' in Figure 15, Figure 1? is a section on the line XVil -XVII in Pigure 15, Figure 18 is a section on the line XVIII-XVIII in Figure 15, Figure 19 is a view sitdlar to Figure 15, hut showing the carrier partially projected, Figure 20 is a view similar to Figure 15, but lowing the carrier fully projected, and a finger mechanism activated, Figure 21 is a detail plan view of one end of the product carrier shown in Figuro 15, Figure 22 is a view looking in the direction of arrow XXII in Figure 20, shewing the pack opening mechanism in an operative position, Figure 23 is a detail view of a finger operating mevhanism, Figure 24 is n dingrammtic plan view of a product f«ed fraaework, Figure 25 is .1 view similar to Figure 17, but showing a pusher mechanism, Figure 26 i3 a plan view of the mechanism shown in Figure 25, 3 9 u t; ? KilVUiv i?t is -• plan view of a pueh« r cam arrnnc.omi'nt, f'ij^uiv 28 is a rapeolive viow show in'* the position after formation of .*i film tube with a l'inpur opening mechanism in th«- cLooed ponition, figure 29 is n jx.rspccfcive view showing tho position of a tube after operation of the finper opening moch'inism, Kifrurc 30 in « perspective view ahowinp? in nlt-.-rnative form of tub<: opening mechanism, and Figure 31 i" M iHrtftjnmmtic repro3 GENERAL LAYOUT OF MACHINE.

Tho mnchim.' is constructed as doscribcd in detail in Patent Specification No. 38024 , nrbi only so much detail of the machine 113 is necessary for an understanding of tho prvscnt invention will bo described here.

Tho purpose ol" the m-wfiine is to wrap articles of ■■ priamaf. ic shape, tji'l in t,!> i: part.icular inst-mco, the nm:hu:<-i nti.-fnlt.'l to wrap roll:: oJ" wllpaper, which pr-sont ,*< probl-m i e ■ that th«.y ire lonp: ivlntiv. ly narrow articles. The rolls must h-completely envclopod in he-it sh linkable plastics film ouch is polyvinylchloride, r<. idy Tor passing through a shrinking zone in which heat is applied to tighten the film on the paper roll.

Tho machine is a processing machine having a series of stagi.-s at which a Sequence of pack-forming steps is curried out. In this particular e.-.chine the stager. arc arrajipjetl alnn,'; a horizontal path throuph tho machine (the p->th Ixiinft indicated by the lino 10,10 m Figure 2) but it in t.<> bo under;;hood that this Ls =• m-i.t.-.r of coma niene- , -url Die nachir:-.- ecu 1(1 be Tranged with a non-horizontai path- 39067 At tho input of thu nachino (shown at the left hand end in Figures 1 to 3) there is a filn feed arrangenont generally dosign-tud 12. Tho filn feed will bo hereinafter described in detail, but, it will be nentioned that there arc 3> vertically spaced countings for reols 14 and 16 of tho hoat shrinknblo plastics filn, one above nnd onu below thu horizontal path 10.

The nn chine is adapted to bring the two filets together n»l to produce a series of separate packagos therwfron, as will 10 be described, but it is nucessary to mention at this stage, that the filn travels successively over three conveyors; nanely - a filn feed conveyor 18, a wrapper conveyor 20 and n shrink tunnel conveyor 32. The latter passes through a 8hrink tunnel 24 nt the output and of the aachina, this 15 tunnel being a known apparatus in which heat is applied to the envelope of filr. to shrink that filn into tight engageaont with the articlc being wrapped.

Tho general path of the filn through the machine as scon in plan is indicated by the chain dotted line 26,30,32 20 nnd 3^ in Pipure 3. Pron tho filn rcols 14 and 16, the filn paese3 in the poth 26 at right angles to tho general longitudinal path through tho nnchine; then is turned through 90°; thenit travels along the path 30 which is parallel with the general longitudinal path, and it loaves the nachine 25 along the pith 3^ which is parallel with the general path.

It is to be observed however, that the paths 30 34 are offset fron each oth<.-r, and there is a short inclined path 32 between then, which is an inportant feature of .the invention.

In front of the three conveyors 18, 20 and 22, thcro is 30 a product conveyor 36, and it will be seen tbht parts of this conveyor aro alongside parts of all three filn conveyors. - 10 a a o»; ? The product conveyor 36 includes -i series of carriers 38, which will bu described in aomu detail hereinafter. It lo to be notod howovur, that the carriers 38 do not travel in a rectilinear path a:j sucn in plan (Figure 3) but in a prith designated 42, 44, 46, 48 and 50. During tho part of the carrier eye lo indicated by tho lino 4©, a enrrier travels with a compound movement in the g&noral longitudinal direction and also rearwardly towards tho path of the film. Along the path 42, the carrier 38 travels parallel with tho fila, and then it travels in a compound stepped movement, indicated by the linc-3 44 , 46 and 48 forwordly, nway froa the path of the fila, and then along tho prith 50 parallel with the general longitudinal direction. Prom the path 50, the carriers 38 return axong the bottom run of the conveyor 36. The wrapping function is performed bj interaction of tho articles carried ty the product eonvoyor 36 and the film as it travels along the convoyors 18, 20 and 22.

To the rear of the Tilm feed conveyor 18, there is a housing 54 for tho main driving mechanism (not shown) of the machine, this driving mechanism including on electric motor nnd suitable gearing. A control panel 55 is also provided, this being connected to the housing 54 by a trunk 57.

FILfi FEED.

The film foud 1.' in •*« known t.yj*; and the 1-sit" ore riot.tl not be deneribod in ^reat detail. It i3 designed to store tho two reels of film 14 and 16 alongside tho machine (see particularly Figure 1) so as to keep tho overall length of the machine as short a3 possible. The axes of the reels are therefore parallel with the ge-ncral direction of travel through tho machine. The reels arc supported on u 30007 stationary frame 52 which may form part of thu general fixed structuro of tho machine, (as illustrated in Figure 1) or it may be a free-standing unit which is simply placed is close juxtaposition with tho housing 54 for the main driving do chonisn.

An arm 56. extends forwardly from the housing 5^, ond at its extremity, it provideis n support for one end of a cylindrical rod 58, the other end of which is supported in a lug 60 on tho frame 52. Tho rod 58 is inclined at 45° to the axe8 of tho film jxel3 and to the general path of thu film through thu machine - as seen in plan view. This rod provides a ouona for chnnpinc tho direction of travel of tho film throuf^i an anp.lA- of 90°. The rod 58 is in a position to receive the- filn from the upper reel 14, and there is a similar rod 62 for the fila from tho lower reel 16, tho rod 62 being supported at one end in a lug 64 and at its other end by an arm (not visible in Figure 1) which is similar to the ana 56.

Two sets of film tensioning rollers arc provided in the film feed assembly 12, one set for each film reel. The upper set comprises throe parallel rollers 66, 68 Tud 70 each extending across the pnth of the film fiom the reel 14 to the rod 58, these rollers being journalled so that they are able to rotato about their respective longitudinal axes. The top set also includes two rollers 72 and 74 mounted parallel with the rollers 66 , 68 and 70 and intordigitated therewith; Each roller 72 ana 74 is free to rotate about its own longitudinal axis, and in addition, its axle is free to rise and fall in corresponding vertical slots 76 (two of which can be seon in Figure 1) formed in the frame 52 and in tho housing 5^. 39067 . Th*. film 80 from thu top reol 14 passes in a cinuoua path over th*.- roller 66, under roller 72 and over roller 68, under roller 7^ and over roller 70 to the rod 58. In turning under the rod 58, the filn 80 is then passed in a direction indicated by tho line 30 in Figure 3 longitudinally of the machine.

Tho weight of the rollers 72 and 7* is carried by the filr BO, and consequently these rollers tension the film. Also the •iauous extension of tho film provides a film reservoir whiah line already beon pulled off the reel 14. If tho machine requires film sore rtpidly thnn it can conveniently be withdrawn fron the rcol, then the extra film is drawn from the reservoir, the rollera 72 arri 74- rising to shorten tho pnth through tho reservoir, "onversoly, if the film requirement of the machine is loss tha.. tho rate of feed from the reel, then the rollers 72 ^nd 74 ire loworod and the length of the film reservoir is increased.

The lower sot of tensioning rollers comprises three statioaory rollers 82, 84 and 86 and two vertically movable rollers 88 and 90, in an arrangement which duplicates that of tho upper tensioning; roller:.;. Tho film 92 fron the lower reel 16 passes through tho reservoir provided by the rollers, 82, 88, 84, 90 and 86 and then under nn extra guide roller 93 before turning under the turning rod 62 in similar fashion to the upper film 80.

The film feed is completed by upper and low_r pairs of nip rollers 94 and 96 which aro vertically spaced from each other, thu rollers of each pair being spring loaded towards each other, and a pair of guide rollers 98 and 100 which are spaced apart a short distance. After leaving th- turning rod 58, the film 80 passes through the nip rollers 94 and then under the guide roller 98. The film 92 on the other hand, after leaving its turning rod 62 passes through - 11 ~ 3 9 0 U 7 tho nip rollers 96 and over tho guide roller 100.

At tho guide rollers 96 and 100, the two filoa BO nnd 9?. form a mouth, but boyord theso rollers the film layers are brought together in face-to-face relationoip by n nechanisn to be descd>od, so that they are ready to bo foraed into an envelope. Ike film feed provides a aunna of supplying the filn from the two reels 14 nnd 16 to the rollers 9H and 10;*). It in, of course, nucensnry to enrturu that tho two filar, nv corructly aligned with o'ich other transversely of the cnchine, and generally tho films will be of equal width (as illustrated) so thnt their longitudinal edges hnvv. to be brought into overlying relationship. For this purpose an .axial adjustment of tho reels 14 and 16 is provided, no that one- roe* can bo moved in an axial direction relatively to the other reel. This i3 a known method of aligning two filn feeds.

An important feature of the cnctins is that the top roller 98 does not extend far forvardly as the bottom roller 100.

It is to be understood that tho use of a film feud which hns its reels parallel to the ronc-ral path of the filn through the- machine i3 not essential. It would be possible to provide a feed mcchani3m having a pair of reels with their axis transversely din posed, in the nn chine, so that tho film pns3es in a straight path (as seen in plan) to tho guide rollers 98 and 100. 3 9 0 6 7 PI1H SEALING AMD SKVfcBIKG.

From the guide rollers 98 and 100, the two filnn 80 and 92 travel together on the filn feed conveyor 18, (3c« Figures 2 and 4) and 5 \auring tbis period of travelling on the conveyor 18, the films are formed into a series of flat envelopes with open ends, but sealed along their side edges. To this end, it is necessary to apply a sealing and severing device across the filas at longitudinally spaced positions. The sealing and 10 severing device cuts through both filas, and also forms a seal, transversely of the conveyor *18 on each side of the cut, thereby sealing the trailing edge of one envelope and the leading edge of the following onvelope. Each envelope is thu3 formed between two successive applications of the sealing and 15 severing device and whereas there is a continuous feed of fila through the rollers 98 and 100, it is a succession of separate envelopes which 1omv«; tho filn food convoyor 18 and passon ori to th'- wrapper convt-.yor 20.

The conveyor 1ft is of special construction, the purpose 20 of which is to provide a resilient base against which a sealing and severing device enn act. This special conveyor is illustrated in Figures 4 and 5.

A pair of cantilever arms 102 and 104 extends laterally from the main drive housing 5^, under the horizontal path 25 10, and in the region of the film feed conveyor 18. These arms 102 and 104 support the conveyor 18, and are constituted by tubes of substantial dimensions which are secured or welded to the machine framework at their rear ends (not shown). * pair of check plates 1ftf> and 108 arc provided, -md those ore 30 mounted on the arms 10P and 104 and secured in position by nuts 110 engaging on screw-threaded extensions of the arms. There are also transversely extending distance pieces - IS - 39067 (not shown) botwecn the cheek plates 106 and 108.

A driving shaft 112 traverses the cheek plates and is journalled therein near to one end of the plates. This driving shaft projects on tho rear of tho plate 108 into tho housing y* and there is a driven chain sprocket wheel 114 keyed on to this shaft extension. The driving shaft 112 is adapted to be driven through a chain drive (not shown) to the wheel 114, through Rearing from the machine driving motor, so that tho shaft 113 rotatfen continuously at a speed related to that of the nachinc so long as the machine is in operation. There is a parallel idler shaft 116 journalled in the cheek plates 106 and 108 near to the other end of those plates, but this idler shaft has no extension into tho housing $4.

Two chain sprocket wheels 118 aro keyed to each of the shafts 112 and 116, on the outsides of the cheek plates 1CG and 108, and a roller chain 120 passes around the pair of wheels 118 on each side of the apparatus. A tensioning pad 122 is securcd to cach cheek plato in such a manner that it cm be adjusted vertically. This pad 122 is engaged with th«.- chain 120, and ir the chain bocomes slack due to wear, the pad is adjusted to deflect the lower run of the chain downwardly, thus applying tension to the chain to take up any slack.

A guide pad 12^ is also secured to each cheek plate, and this pad has 3 horizontal top surface or: which the rollers of the chain 120 engage as tbey travel along th-% top run of the chain path. The pad 124 is not adjustable and it is important that the top surface of the pad should be in a predetermined position, as this determines the effective path of th. conveyor 18. 3 9 0 C ? An in mora clearly shown in Figuro $, n cbannol 120 ia fixed to tvo adjacent rollers 128 of oach chain 120, theso channels extending across the full width of tho apparatus between tho two chains. i- motal bar 130 io welded on to 5 cach channel 126, and overhangs that channel at cach aido, so that the bare 130 which arc travelling in thu straight upper run of the chains abut cach other to fom an effective platform. Each bar 130 is fitted with a strip of hoat resistant silicone rubber 132, and these strips are of tho 10 same width as their respective bars, so that on the top run, thoy form a resilient platform. Part of this platform is clcnrly shown at th*: right hand side of Figure 5* An endless belt 134 of polytetrafluorooth.ylcnc (P.T.F.K.) io provided on the ov^nidr of tho conveyor formed by the 15 chains 120 and their channels, platos and silicone rubber strips. The belt 1?4 is guided around rollers 136, 138, 140 and 142, and there is a deflecting roller 144 engaging with the outside of the h<:lt tr« tension it. The arrangement of the guide rollers is such that the top horizontal run of the 20 belt 134 is in engagement with the platform provided by the strips 132, and this is tho effective part of the belt. The roller 142 is n driving roller for tho belt 134, and is driven by gearing (not ahown) from inside the housing 54, the rollers 136, 138 and 140 are idler rollers. The drive to the belt 25 134 is no arranged that th- linear spued of the bolt is equal to that of th>. strips 132 and hence theru is aubstantinlly no relative movement betweon the belt 134 ''-nd the platform provided by th.. strip 132 when the bolt and chains 120 arc in operation. - 17 - 39067 The belt 13* raid its associated pint form of strip s 132 provides thu filn feed conveyor 18 previously rcforred to, and it is whilst the two layers .of fila 80 nnd 92 are travelling on the top run of this convcyor that they ore formed into separate envelopes. The manner in which this is achieved is shown diagramnatically in Figure 6. A sealing hood 150 (seo Figure 7) travels over tho belt 134, as will he further described, this hend is periodically brought down on to the films 80 and 92. The sealing head includes on electric resistance wire 152 (see also Figures 12 nnd 13) which is exposed on the lower surfneo of the head, and each tine the head is applied to the films, the wire 152 is heated by passing n current through it. As a result, the wiro cuts through the two fiDns aloni* a trnn6Vt»rne line shown at 15* in Figure 6.

Referring to Figure 13, it will be seen that the sealer head 150 is a block of metal formed with grooves 151 and 153 along itn sidos to receive electric resistance heaters 155 which are scaled in protective sheaths. These hoaters ore constantly on during operation of the machine to maintain the block 150 at a temperature suitable for sealing the layers of film together. A thermostatic device is provided to control tho temperature of tho block 150. When the flat underside 156 of the sealing head 150 passes on to tho top film 80 this seal3 the two filns 80 and 92 together in transverse marginal zones 158 and 160, the zone 158 being on the rear of tho line 15^ and the zone -160 being cn the front of th..- line 15^, having regard to thfc direction of travel of the film (sec nrrow 162 in Figure 6). It is to be understood that, in jiracticc, the seals 158 and 160 ar«; vory narrow, and their width has been exaggerated in Figure 6 for clarity. - 18 - 30007 . Tfo.j sealing nnd severing operation separatee tho continuous film seen arriving fron the loft in Figure 6 through the guide- roll ore 98 and 100, into separate two layer transverse strips such as that shown at 170", moving off to the right. At the aane timo, the loading and trailing edges of the atrip* are sealed to producc an open endod tube of filn - though at the position shown at the right hand end of Figure 6, tho tube is still in n flattened condition.

It nay be observed, that tho filn tube 170 is shown displaced forwardly - in the direotion of travel - fron tho lino along which it was severed from the contimious sheets of film. Thin is because the scaling nechanism includes neans for rapid forward feed fa flicking notion) cf the newly separated tube as soon as tho film is severed, the flicking notion ensuring that the filn tubes arc in fact separated. Tho sepnration of ♦■fcn filn tubes is essential, because the wrapper conveyor 20 travels at a greater surface speed than the filn feed convoyor 18, and the separated tubes have to travel at the same speed as the conveyors 20 and 56.

To assist in feeding tho filn along the conveyor 18, a feed carriage 172 io provided (see Figures 9 and 13) the carriage* having rollers 248 and 250 which rest on the filn and press the filn on to the upper surface of the conveyor belt 154. Tho .carriage 172 has a reciprocating notion, and during its forward travel the rollers 248 and 250 do not rotate, but simply press the fila layers together and on to the belt 1J4, the rollers travelling forward with their cirri172, at the same linear speed as the top run of the belt 154. Consequently the rollers sinply act as nips holding the filn securely on the belt 154. - 19 - 3906? t < The staler "he.-id *150 is also mounted on the enrriago 172, nnd it is no tho carriage bogins its forward stroko, that thu scaler head is depressed to offeet the sealing and severing operation, and at the end of the forward stroke the 3oaler is withdrawn upwardly and the carriage 172 roturns to its storting position*. Tho travel of tho carriage in its reciprocating notion io rmcb that its wheals travel moot of tho length of the plat fom provided by the silicone rubber strips 152, but the wheels never novo off the ends of tho support -iron afforded by that platforn.

The sealing of the two layers of filn is taking place throughout the forward stroke of tho sealing bead. This pemitr. accurate control oi the sealing oporation, which is governed by the tenperature of the scaler head 150 nnd the duration of the application of the head to the film. Thus, by regulating the speed of trr-vcl of the filn and the head 150, the scaling operation can bo controlled.

The nechnnisn for effecting the reciprocation of the carriage 172 and the vertical diaplacenent of the sealer head 150 is shown in Figures 7 to 14 and will now be described in detail.

All the sealer head nechanisn shown in Figure 7 is nountod on tho machine above the filn feed conveyor 18, and within a housing 174 (sec Figure 1). A. driving shaft 176 projects into tho housing 174 from the nain drive housing 54, and is arranged to bo rotated at a speed related to that of the various conveyors, by gearing fron tho nain driving motor. nain driving can 17B keyed to this shaft 176 has grooves 180 in its faces in each of which a can follower (not shown) is Ruided. The can followers are carried on a slider 182 which has slide blocks 18^- running on horizontal guides provided - 20 - 30067 by four fixud guide mils 186. Tho carwind-followcr device thcrofore provides a noons of converting rotary notion of the shaft 17G into rectilinear reciprocation of the ulider 182. In practice, th.. can in nrr-inged to provide a relatively quick forward notion of the slider (in the direction of thu-arrow. 188) and a relatively slow rotum notion in the opposite direction. -iv pair of parallel lovers 190 arc joined by a pivot axle 192 near to their lower ends, and t>*is axle io pivoted in stationary bearings (not shown) no that the lever:; 190 aro able to oscillate about thu axle 192. Jit their upper ends, the levers 190 arc slotted at 19^, and a stub axle 1% projecting fron .a -op ;-Lider block 19& encages in each of the slots 194. The block 198 is fomed by two nenbers engaging respectively on opposite aides of n fixed central Kuirte rod 200 of rectangular cross-section. U cross pin 202 carried by the rear clider block 104 passes through rants (not visible in Figuiv 7) in the levers 190, at a position between the pivot axle 192 and tho connection of the levers 190 to tho top slider block 198. Thus, as tbe slider 182 reciprocates, rocking notion io applied to the levers 190 and these produce a horizontal reciprocation of the top slider block 198. It will be apparent that the slider block 198 travels through a threat r distance than the slider 182 by virtue of the velocity ntin of the lever 190. a substantially triangular frame 204 has its apex fixed to the top side of the top slider block 198, and its two forward apice* arc fixed respectively to top front slider blocks 206, only It in to be understock that the nain can 170 L:.: on the verticil central plane of th. sealer driving ru.chaninn, md that thie nc-chmism i3 symmetrical about thin control vi.rtic.nl plane. Consequently, the front top slider block 206 - and -ill the nechanian associated therewith, which is noro clcnrly ohown in Figure 8, is duplicated below tho other front corner of the triangular frnno 204. 8ince this ncchanisn is merely duplicated, it ic not illustrated to avoid rinking thu drawing unduly conplcx.

The blocks 206 arc similar to the block 198, and slide An respective fixed horiaontal rods 208 of rectangular croau-cectir.n. Ht-nco, during rotation of the can 178, tho >ntirc top frrsne 204 with ito three slidera 198 and 206 reciprocates in a horizontal plane.

Each fixed rod 208 forns part o? a trapezoidal fixed frnne at its own side of the sealer head and filn feed nechaninn. This frnrc includes a parallel horizontal rod 210 at a lowor position, th> t:r rods 208 and 2*10 beinp spaced -»part and hold together by a roar vertical strut 212 and a front inclined strut 214. 4>- pair of coaxial stub axles 216 project from opposite faces of each front top slider 206, these axles engaging in slots 218 in the upper ends of a pair of levers 220 disposed one on each side of the inclined strut 214-» The lower ends of the levers 220 erbrace n front botton slider block 222 similar to the top slider blocks, and running on th-: botton horizontal rod 210. The blocks 222 are fixed to a transverse inverted channel 225 which forns pirt of the corringo 1?2.

The. fulcrun f^r the levers 220 is provided by a pair of coaxial stub axles 224 projecting on opposite sides of a sleeve 226, which embraces the inclined strut 214. -..s is clearly shown in Fif^urc 8, those axles engage in slots 228 in the I'.vcrs 220. Thus, 13 the slider block 206 moves - 22 - 390 6 7 forwardly, the block 2?2 ia novod rcarwnrdly by virtuo of the notion of the levers 220, and therefore due to the action of the nain con 178, the carriage 172 has ci slow advance movement in the direction of the arrow 250 and a quick return novenunt in the opposite direction. t The shaft 242 is coupled to a neans (not shown) for rotating it and these neans are preferably nanually operated. Por example, there nay he a control knob on the housing 1?4, so that the nachino operator can, by turning the knob, rotate the adjusting shaft about its own longitudinal axis, .'alternatively the shaft 242 could bo geared to a small electric notor, controlled by push buttons, so that operation of the notor in one direction causes rotation of the shaft 242 in a clockwise- direction, and operation of tho notor in the opposite direation onuses rotation of the nhnft 242 in the anti-clockwise direction.

Kow, it will bo apparent, that when the shaft 242 rotates, tho screw 234 is also rotated, and this causes the sletve 226 with its fulcrun axles 224 to b<; raised or lowered. - 23 - 30067 Raising the fulcrun increases the length of stroke of tho enrringe 172, nnd lowering the fulcrun reduces thnt stroke. Further, since tho mgulnr velocity of tho can 178 ror. tins constant (so that tho cycle of tho carriage 172 always takes the sine length of tine) increasing 'jhe longth of travel of the carriage also increases its velocity .■and vice versa.

The levers 190, franc 204 and levers 220 together forn a linkage for operating tho reciprocation of the carriage 172. It is possible to vary tho stroke of the carriage by adjusting thu effective length of my one of the elcrvnts of this linkng«-. *-d;justnent of th..- fulcrun for tho lovers 220 provides a sinplo nr.d affective way of doing this.

Referring now to Figures 9, 12 nnd 13, the carriage 172 conprisos the inverted channel nunbor 225, which extends tmnnverru ly of th. •■•ichine, nnd from which th*-re depend four 246, two nn th< loading odgo of the- channel nnd two on the trailinr, <-dge thereof. The two landing legs 246 provide Journal nountings for the leading roller 248, and the two trailing 1( ps provide a sinilar nounting for the trailing roller 250. The position of tho slider block ~22 is indicated in Figure 9 by the holes 252, which are the bolt holes for fastening the block to trc channel 225. The rollers 248 nnd 250 roll on the filn as it is travelling on tho belt 134 (filn focd conveyor 18) nnd nip the filn on to that bolt to control the filn during the sealing arid severing operation.

Extending olonp: the- roar side of tho carriage and seller head ncchanisn (and within the housing 174) is n roll.-r chain nssenbly 254 the length of which coincides ipproxinntoly with tho length of the lower chain 120 (see Figuro 4). Thib anscnbly includes an •indlesf chain 256 extending around two 390 67 chai'i sprocket wheels 25*"- '*nd 260 on spaced horizontal shnfts. The shaft 262 of the sprocket wheel 260 extends into tho nain drive housing 5*S and carrics n driven sprocket wheel 264 by n chnin 266, which is itself driven fron the drive to the lower choin convcyor 120. The arrnngenent of this chnin drive is such that the lowor horizontal run of the chain 256 noves in the forward direction indie.- ted by the arrow 268 at a linear speed equal to that of tho top run of the strips 132 and the top run of the P.T.F.E. bolt 134. a shaft 270 in extension of each of the rollers 2^8 and 250 carrics a sprock'. t pinion 272 which < ngages with the button run of the chnin 256, If one ccnnidcrs the chain 256 to be stationary, then as tho carriage 172 is noved forwardly, the rollers 248 and 250 are caused to rotate in a clockwise direction as seen in Pigure 9, and as the carrics 172 noves rearwardly th»; rollers 24% and 250 aro caused tc rotate in an anti-clockwise direction. But tho ncvenont of the chain 256 pre aces only a differential tronslationol novencnt between the pinions 272 and the botton run of the chain, and in fact where this differential is reduced to zero, the rollers 2^8 nnd 250 do not rotate about their own axes, but nerely h.nve a trnnslational novenent with the carriage 172.

Now it has olr. ady tv.-..n r.entioned that she bott^r, run of tho chain 256 is travelling at the sane linear speed as the top run of the strips 132 on the filn feed conveyer. Therefore when the rollers 248 nnd 250 do not rotate about their own nxes on the forward travel, the carriage 172 is n«-«vinp: in synchronism with the fil» feed conveyor and at the sane linear speed. 3 9t>07 At the front end of the trailing roller 250, there is an indicator disc 274 (sec Figure 11) which is secured to a short shaft extension of the roller 250, passing through a leg 276 secured to tho channel 225. pointer 278 is fastened to the front of the leg 276, and projects over the face of the disc. The latter io divided on its face into alternate dork and liRht sectors. This fact of the disc 274 is visible nn the front of the housing 174, and (rives a visual indication tu any relative novenont botw< « n the carriage 172 nnd the lower run of the- chain 256 when the carriage ir, advancing. If there is no relative revenent (which is the desired condition) then there will bo nc r^tatiori of the disc 274 as indicated by the finger 278.

If the indicator 274 shows that there is relative ncuvcrnnt of the carriage 172 over the bolt 134, it is necessary to adjust the speed of travel of the carriage as otherwise there would be a tendency for the rollerR 248 and ?50 to scuff the filn or cause it to crease and curl. It is, of course, possible to adjust the speed of travel of the carriage by repositioning the fulcrun 224 as has been previously described. It will be seen therefore that the chain sprocket driv.; 254 provides a neanr. of synchronising the advance novtnnl: of the carriage 172 with that of tho filn feed conveyor 18.

I>uriJifi the return motion of the carriage, there i3 a larn<- differential -^ovenr.nt between the pinions 272 and th-.j chain .'?56 and the i';>lli_rs 243 and 250 rotate rapidly but this is not inpTtant. In fact, the Ditch circle dianetev of the sprocket wheels 272 is equal to the outside dian^tor of the rollers 248 and 25CU Consequently on the return 39067 notion the carriage 172, tho rollers 246 nnd 250 have a surface speed cqu.il to that of tho bolt 134 on which the filn is travelling and therefore the effect ia that of pAssing the filn through a pair of nip rollers (i.e. there is no slipping between the rollers 248 and 250 on tho on»i hand and the bolt 134 on tho other). ub is clearly shown in Figure 8 there are pairs of pillars 280 upstanding fn>r the channel nenber 225, and a three part bo* bean 282 is slidable vertically between those pillars. Tho pillars 280 havo depending legs 281 extending below the web of the channel nenber 225 on.6 tho upper part at the scaling head 150 has pads 283. one on each side, these paJ.; being node cf wear-resisting plastics material, and rubbing on the legs 157. Sinilarly thert are pads 285 of wear-resisting plastics natorial on the sides of tho box bean 282 for rubbing on tho inside facos ->f the pillars 280. The pillars 280 arc grooved as indicated at 287 to receive the ends of location pegs 289 and 291 projecting respectively fron the bean 282 and the head 150. These pegs serve to prevent twisting cf the bean 282 and the head 150 in the guide pillars 280. This bean foms n part of thv. scaler, and studs 284 (see Figures 9, 12 and 13) fastened at their upper ends to the bean 282 pass through clearance holes in the web of the channel 225 and are sccured at their lower ends to the sealing head 150. A conpression spring 286 surrounds cach stud 284 and acts between the top surface of tho channel 225 and the underside of a distance piece 283 located inside the bean 282 and v.ngaf^ing with the top tbort.of, thereby holding tho benr 282 in its nomal inoperative raised position, wher'-' the head 150 is in engagenent with the underside cf the veb - 27 - 3906? of the channel 225* In this position the severing wire 152 is dear of the filn on the conveyor 18, tho filn being gripped by tho rollers 248 and 250. fho nochanisn for pressing down the sealer head 150 to carry out a sealing operation is shown in Figuros 7, 8 and 14. k forward extension 288 of tho nain drive shaft 1?6 is provided with a sealer can 290, the front end of the shaft 288 feeing supported in a fixed bearing (not shown). A- pin 292 carried by the upright strut 212 provides a bearing for a conpound link conprising a pair of parallel links 294 joined together at the trailing ond by a cross piece-295. Tho links aro fornod with slots 296 which receive the pin 292, so that the link can slide on tho pin. h. can follower 298 is supported between tho links 294 and is urprcd into engagement with the profiled periphery of the can by h conpresnion spring yx) acting between the trailing side of the strut 212 and the cross piece 295• A bell cranked lever 302 has a pivot pin 304 supported in fixed bearings (not shown), one end of this lever being connected to t-^e leading end of the links 294, and the other end being connected to a cross rod 306 which forns part of a depresser frane 308. This frane 308 consists of side bars 310 connected by cross rods 306 and 312, and the entire frane is nounted in guides (not shown) so that it is free to nove vertically. Thus, as the can 290 pushes tho follower 298 and the links 294 fcrwardly, the consequent rocking of the bell cranked lever 302 causes the depressor frane 308 to be lowered. To assist in providing for vortical n"vcnent of thu depressor frnne 308, thore nay bo a further b«-?ll cranked lever sinilar to ths lever 302, this furth Tho can 290 is shaped so that it produces the depressing action as tho carriage 172 is at its nost retarded position (i.o. nearest to tho filn feed end of the nachino) and the can is further arranged to hold tho frane 300 in tho depressed condition until the carriage has arrived near to its nost advanced position* A series of four trolleys 31^ (only one of which is shown in Figures 7 and 8) is provided. There is one such trolley on cach outer part of the bcaa 282 and one near to each end of the niddle part. Thus there are two trolleys at cach side of tho nccharisn, and each has a pair of wheels 316 running on the underside of one of tho side bars 310 of the depresser frane. The trolleys provide reans whereby there is provision for notion between the carriage 172 and the depresser frane 308 which can only novo vertically.

It will now be clear that during the return notion of the carriage, the scaling head 150 is clcar of the filn, but the rollers 248 and 250 ore holding the filn under control. In fact, those rollers never leave the top surface of the filn 80, and hencc they provide tho neans for nipping tho two layers of filn 80 and 92 on to the surface of the conveyor 18. These rollers 248 and 250 and the co-opnratin^ conveyor 18 provide the nip for the two layers of filn which holds the layers in the required face-to-face relationship.

During the advancing notion of the carriage, the rollers 248 and 250 nip the filn anil the sealer head 150 is lowered to press the underside of the head on to the filn. The wire 152 is pressed into the filn and the resilience of the platforn provided by the strip 132 allows the wire to press - 29 - 39067 into the belt 1>4 to ensure that there is a close control over thv. heat sealing and severing process. Towards the end of tho advance ncvonont of tho carriage, the head 150 is allowed to rise under the action of the springs 286.

A short am 318 extends fron the leading sido of the box bean 282, noar to its rear end, and this carrics a depending leg 320 forned with a gear tooth rack 332 (see Figure 10). A unidirectional clutch or frocwheel dovice 324- is provided on the shaft 270 of the leading rollor 248, and the outer race of this device is forced as a gear wheel 326 which ncshes with the rack 332. The frecwhoel device is arranged t<~. transrdt anti-clockwise notion to the shnft 270 (as set.n in Pigure 10) but not clockwise notion.

Vhon the sealer head 150 is depressed to of feet a seal, the rack 322 transnits notion to the wheel 326 but this is not transferred to the shaft 270. However, when the sealer head rises, the rack 322 rotates the shaft 270 rapidly in an anti-clockwise direction. Now it this stage, tho rollor 250 is on the lending end of the supply of filn 80 and 92, but tho roller 248 is only on tho newly fomed tube of filn 1?0, which should be separated fron the rest of the filn. Tho sudden and rapid rotation of the roller 248 flicks the tube 170 forwardly separating it fron tht rcnainder of the filn.

The operation of the scaling nechanisn can be explained by roforc-ncc to Figure* 31, wherein certain ir*p<-.rtant < lenentp of the rochanisn arc illustrated diagrannaticnlly.

The nain drive r.ct^r for the nachino is connected via a variable ratio transnission (not shown) to the driving shaft 176 carrying th; cans 178 and 290. The number of ( 3806? packages produced in a given tino is governed by the *. * angular velocity of the shaft 1?6 because tho filn is severed each tine the can 290 causes the sealing head 150 to descend. This angular velocity is preselected 5 by .setting of the? transmission ratio between the driving notor and tlie driving shaft. 176.

A second voriablo ratio tronsnission is provided between the shaft 176 and tho drive to tho filn feed conveyor 18, and by adjusting this transnission, it is 10 possible to detomino the longth of thu packages produced between succcssivo transverse seals. The length of the stroke of the sealer head 150 can also be varied, by adjusting tho position of the fulc-^m 224.

Row the proportion of oach cycle of the can 178 which 15 produces forward novenent of the sealing head 150 is fixed by the shape of the can and the period of oscillation of tho can is detemined by the (already chosen) angular velocity of the shaft 176. Hence the length of the packages is varied, it is desirable that the length of the forward 20 stroke of the sealer head should also be variod to patch the speed <-*f travel of the head to that of the filn.

For oxanple:- Suppose that the cnr. 178 causes tho head 150 to travel forward for $ of it9 cycle and return on the renaining -J of its cycle. Then if the driving shaft speed 25 and the filn feed conveyor speed have boen selected to product flat tubes 6 ccntineters long, the forward stroke of tho hend 150 nust be $ x 6 = 4 centinoters. If flat tubes 12 centinetcrs are beinf? produced, then tho length of the forward stroke nuat bo adjusted to 8 centinoterB. 50 ^hfc facility of adjusting the stroke of thu head 150 therefore enables packages of different sizes to be prMucod. - 31 - I ■ V: 30067 and it is nn inportant rvtvantago of the arrongcncnt that thu mljustncnts of driving shaft spcod, filn feed and longth of stroke of the seoling head 150 con all be nnde whilst tho nachino is in operation. 5 It is also to bo observed that the sealing head 150 is naintained in n constant orientation rolatively to tho path of ncvcr.cnt <~>f the filn, nnd that tho hood hns a perpendicular ->ovencnt relatively to the path of th<; filn for the purpose "f applying sealing pressure 10 to tin filn. - 32 - 3906? tJBODUCT PEED aHD TUBE OPENING MECHANISM.

It has already boon noted that the articles to he wrapped are fed through the machine In synchronism with thu filn feed by means of n product conveyor 36 with carriers 38* Tho product feeding mechanism is provided in a housing 328 which extends along the front of the fila feed, fila feed conveyor and part of the shrink tunnel conveyor 22. This mechanism will now be described in detail* Heforring to Figures 15 ood 21, the conveyor 36 essentially consists of a pair of endless roller chains 330 wrapped around sprocket wheels 362,364,366 and 368 (aeo Figure 24) which are arranged to provide long horizon^1 upper and lower runs of the chains. The two leading sprocket wheels 366 and 368 are on a common shaft end the two trailing sprocket-I'/heela are on a second comaon shaft.

However, the shnft 370 carrying the leading sprocket wheels extends into the main drive housing 5*» where it in geared to the nnchine <1 riving motor. Thus the product oonveyor 3b is driven in timed relotionship with the film feed conveyor 18.

A plurality of the product carriers 38 is provided and cach has two parallel carrier rods 334 and 336 (see also Figures 16 to 18) which extend transvorsely of the conveyor. At its ends, the leading rod 334 has extension pins 338 which fit directly into hollow pins of the ohains 530, so that the chains carry the rods 33^ with them. The rods 336 are connected to the chains by swing links 339 so that they are free to move up and down relatively to the chains. - 33 - 39067 ii ch carrier 38 has a body 343 »wbich is nado as n Moulding in metal or plastics, fleference to Figure 1? ehows that this body 340 is generally channel shaped. At onch and of the c. rrier 38* there is t* support block yil or 34 J. 5 portions 34? depend iron tho block 341 and aiailar wing portions 3^4 depend froa tho inner block 343 (boo jfigurca 16 to 18) and there are holes in those wings to receive the rods 33/* nnd 556. In addition there aro slide rods 345t and the body member 340 is free to slide on the 1f> slide rods 345 (i.e. it is free to aove transversely of tho ua^hinc). nn article support tray 346 is secured to the two body nenbers 541 and 3^3, p.cC r.s is clearly shown in Figures 16 to 1b, thi3 tr«y is of generally chennel-shaped crossly section but its inner walls arc inclined towards each other townrdr, the bottom, r.o thnt the tray is adapted to support rolls of wallpaper of •lifferent di%seters after the Earner of t Vee block. Figure 18 illustrates in chnin dotted linos a larger diameter roll R ;.:mi a sr.aII di.-meter roll r icd it .?0 will be observed that both can fit snugly into the tray 346.

A slipper block 3^8 at each end of the outer body ^eafcer 340 runs on n. guido plate 350 to-hold the carrier 38 onto the path determined by the plate 350, b^t the slipper block is free to leave the plate 350 when the carrier is turning round at the end of the conveyor 56. 3elow the our..r body noaber 540, there is a downwardly projecting colunn , -'hich at its low^r end provides r. support for a slider 55^. This slider rnay t:ke the fom of a roller rotot-bie ;ibouc •= vortical axis if roouirec.

- .U - 39067 Referring now to Figure 24, the product food housing 328 comprises side frofto members 356 358 connected together by rigid spacer nenbera 3^0. The product conveyor 36 ia a chain sprocket conveyor and is guided on the aprockct wheels >62, 564, 366 and 366, the shafts of which arc journalled ir: the side frame members. a tray coo track 372 is fixed on tho frouework of tho product feed mechanists ond consists of a channel within • fhich runs the slider 35^ on tho outer body Bomber 340. In Fi^ur# 24 only thu centre line of the tray can 57? is shown. The can track is endless and follows a general pattern of tho product conveyor itself, as seen in elevation. However, the top run of this track comprises n short mm 374 parallel to the (?:nvral directjon of the product through tho machine, a renrw.rdly inclined portion 3?6, n second portion 378 parallel to tho general direction of the product through the machine, a forwardly inclined portion 380, a third portion 582 in the general direction of travel, and a final forwardly inclined portion 584. The major part of the return run of the tr-'ck i3 inclined to return from the forward position at tho outer end of the portion 384 to tho said portion 374 at the input end.

As the c: rricr 38 is travelling along the top run of the conveyor, the slider 35^ follows the path of the tray can track 372, the portion 376 of the cam track producing a rearwardly inclined travel 40 shown in Figure 3 nnd the forwardly inclined portions of track 380 and 384 oroducing the corresponding forwardly inclined motions and of the carrier. Hence it will be seen that tho car. tr-.ck 572 is used to produce tho transverse novenents of the carriers 38 as the latter travel along the top run of the pro:luct conveyor i>6. - 35 - 30UU7 E/ich carrier 3ft is provided with n finger opening ntfchnnian indicated generally at 30* in Figures 15* 16, 18, 20 and 22. Two opening shafts 388 and 390 extend along opposite sides of tho carrier 38 and each is provided with on operating plato 392 which la secured to th* ibtit 388 or 390 for rotation therewith. -A finger plato 394 is counted for (vution oa tieki of th« 388 ain4390. Tho two finger opening nccfrmisraa are identical, excepting that they are adopted to operate in opposite directions, so that it is only noceoaary to dcHcrlbe one in detail. torsion spring 396 wrnppod around the shaft 388 has one limb 398 engaging with the underside of the plato 394 and the other limb 400 engaging with the top side of the pla"*"? 392. Thus th« spring 396 normally holds the plate 592 flat on a lug 402 projecting fron tho plate 394 so thar the plates 392 and 394 are almost in the same plane. When the finger opening mechanism is in tho inoperative position shown in Figure 15* the plate 394 associated with the operating shaft 388 overlies the corresponding plate associated with the shaft 390.

Each finger opening nechanism includes three rods 406, 408 and 410. Tho rod 406 is fixed to and projects re/irwnrdly fron the rear end of the carrier 38. Each of the rods 408 and 410 is connectod to the plate 394 by screws 412 which pass through slots 414 in the plote so that it Is possible to adjust the literal displacement of tho fingers ix-intivoly to the longitudinal centre line of the carrier 38, nnd relntively to each other.

If tho shaft 388 is rotated in an anti-clockwise direction as seen in Figures 16 and 22 from the inoperative position where tho plate 394 is substantially horizontal to tho operative position 'shown in Figure 22, then the operating 3 9 0 G 7 plate 5'i2 moves throurh an angle somewhat greater than a right angle and carries tho plato 394 with it. However the movement of the plate 39^ is restricted (as will appear hereinafter) and during the final port of the movement of the plato 392, the plate 394 remains \n a substantially vertical position nnd she plat.e is .allowed to complete its notion by opening tho spring 39b- At its forward end, thu sh?fc 3^8 .'-as o port ion 416 of slightly enlarged diameter ."-id o p«r!» helical groove 416 i3 formed in this enlarged por^cc (.ice j*g.»re 2^). A trunnion r:o:->ber 4."V i.". ;il M'iblu on 1.1^ io«l 'j ">" '»rd iiM.i a spigot 42,' which iu the hoiicol j^oovo 4 10. <\ Mlidor ner.ber 424 project- below the body of tN; fci-unnicn member 420, and as illustrated in ?igur«38 '>5, 19 -md ?0, this slider 424 engager, in a channel shaped finger operating track 426.

This tr.-ck 426 is arranged in an endless path similar to fchrt of tho tray cam track 372, the axis of tho track 426 being indicated in Figure 24. It will be ob3er.*ed that throuchout the greater port of the length of thin track, it is parallel with the track 372. However, at 428 jhero is a section of the tr-':ok 426 which diverges rearwordly fron the tnck 372 and at 430 there is portion of the trnok 426 which converger, with the track 372.

Now it will be apparent that so long »s tho two tracks 372 and 426 are parallel, the. ::licier3 *5^ ''iid 424 crust novo in par;illcl paths .so tbat there is no rula'.ivo iuovement between the trunnion 420 and tho romainder of the- carrier 30. Vhen the slider 424 tr. verses the section 423 cf this track, it moves rearwardly along the rod 33*S and since the shaft 388 is locked against axial movement, tho rectilinear notion of the trunnion is converted into rotary notion of the shaft 588. 39067 In practice,jth© po^t h.«licqI groovo 418 is arranged to prodUcci-i05° rotaiy novecwnt of tho shaft 388 during this renrw-jrd strdke of the trunni a member 420. The shaft 388 renains in this turned position through the movement between the trnck portions ,428 and 430, and then when the slider 424 traverses the track-portion 430, the trunnion member is moved forwcrtily on the rod 33^ to turn the shaft 388 back to its original orientation.

Thus the tr»ck 426 produces tho rotation of the nhftft 388 which is required to turn the finger operating mechanism 386 fron the inoperative horizontal position to the operating vertio.il position. It will be appreciated that there is a similar trunnion i.>enber operating on the shaft 390 and that the slidera of the two tr Pinion uenbers both run in the sane track 426. However the slider of the shaft 388 leads that of the shrift 390 in the trick, so that the shaft 388 turns a little in advance of the shaft 390. Hence the plate 39* appertaining to the shaft 388 lifts out of the way of the plate appertaining to the shaft 390 before th« latter cooaenrus to move.

As will appear hereinafter, tho finger opening mechanism provides a neans of opening one end of the plastics tube 1?0, for tho insertion of the roll of wallpaper R. However, a pusher nochanitn has to be provided for pushing the roll R Urunsversely of the carrier 38, into the tube 1?0. Referring to Figures 25 and 26, a pair of brackets 440 and 442 is provided at each end of the carrier 38, one such pair being connected to the body member 3A0, andi the other to the rear end of the tray 346. A pair o£^f>6B]p&r guide rods 444 and 446 extends longitudinally of th» carrier 38, each of these guide rods being supported in two of the brackets 440 and 442. 3806? (The pusher mechanism hns been omitted froa Pigures *5 to 20 for clarity). A pusher block 448 is slidably mounted on the jTiide rods 444 and 446, r>nd is thereby able to traverse over the tr.'iy 346 of the c.'trior 38* A thrust rod 450 projects io rw.-rdly fron the pusher block 448, and at its rear ond, thin i\>d 450 carries a pisher disc 452, which ie of aize convcn'.ent for cng.-iguacnt with the end of roll R to be vrrappod. Tho length of the . thrust rod 450 in such, that tho lusher diac 452 can phsn ovor the finger opening nechaniar.i $P£>, when th«* pusher block 448 arrives at its rennaost position, vhich is approximately in linu with tho rear end of thu tray 546.

Two fixed cctn members 4^4 and 456 aro provided above thu product conveyor 36 (see also Figure 27). tvich of these car. members 4S4 and 456 coau.L3ts of a straight angle iron, supported on brackotu 458 which extend upwurdly fron the framework of the product feeding ciechanism housing 3?.8, the brackets 458 having cantilever type oms at their upper ends, which hold the can nentars 4^4 and 4% suspended above tho product conveyor 36. « cylindrical follower 46o projects abuv.. the pusher tilock 'i4H, and in i»i vertical aljgnneut with the can iiUab'Ts 454 nnd 4^6. It; will be seen from Figure 27, that the can raeober: 454 in inclined renrwardly in the direction of movement of the conveyor 36, and consequently, when the follower 460 engages with this can nember, subsequent longitudinal traverse of the carrier 38, produces * rearwtrd transverse novament of the pusher block 448, with its disc 452. This is the novoment rfcqfcired to push the roll R rearwardly into the opened-out tiaOo of plastics filn 1?0. - 39 - 3 9 0 6 7 The con taoiibcr 456 is arranged beyond thu enn nenbar 4^4 in th.. dirv.ction of travel of the convcyor 36, nnd is inclined forw- nily relatively to that direction. Conse- uently, when the; follower 460 anfrsigcs with tho cnn uenbor 4-56, furthor >rogrt:a3ion of the carrier 38 causes the pusher block 448 with its diac 452 to bo rctractod to the original forward position, where the disc 452 lies in front of the position to which 1 roll d will be fed when thnt particular carrier returns to tho input end of tho nachine.

It will be seen therefore, that this sinplp armngenent of overhead fixed cm:; tracks, operating in conjunction with a slidable pusher or. the carrier 38, provides a aexns of pushing the roll R renrwardly, and then returning the pusher to itG original position.

At; the input end of the product feed conveyor 36, rolls of* wailpaper 3uch as K, are placed in the carrier tray a 346 by h 'i:d. It will be appreciated, of course, that thern enn be .!utoM.;tic feed nechnnisn ' for delivering the wallp/.per rolls rc the curriers 38 fron a preceding operation. VAien a carrier 38 noves rearw .rd.ly in the direction indicated by the line 40 in Figure 3> the rods 406, 4C8 and 410 of the finger -opening nechanisn 386 are positioned in the plane 10, which is between the layers of tho filns 80 and 92. This ■ lovenent cf the rods into the renruo3t position is permitted, because at this position the filna fiO nnd 92 are passing through the nip.s of Uioir respective rollers 94 and 96 and. are therefore widely .-.paced fron each other. The guide roller.". -)8 and 10C .tv : isc spaced apart to accomodate the thickness of the rods 4-06, ^08 and 410 therebetween, and in any event, the rods only pass ovep the roller 100, but do not project below the roller 98. - 40 - I i 3906? ikiring tho subsequent novenent of tho carrior in thu i;oneri] direction i ndicnted by the lino 42 in Figure 3, the rods 406, 408 nn and the conveyor 13J /hilst the carrier 38 is trwor^ing alongside the filn fot»d conveyor 18, the selling rind sevoring necbanisu previously described, opornt-oc to seal and sever tho filn on opposite 3ides of tho set of rods, forcing a flattened filu tube: 17c (ate Figure 6) with the rods <*06 , 408 and 410 projecting into tho front end of this tube.

During tho novei :ent of the c-vrrier 38 indicated by ch^ line 44 in Figure 5, the con 426 operates on tho trur.;ilon . eiibexj; to turn t-lu; :-.hafts 336 nnd 39C, turning: tho finger • f/enirii: 'ii.-ch.'tniai-!:: 3>'*> into their r.:;pective upor.- cive vorti t:'.-l i ositiotuj. Tho fix^cl rods 406 engage with the bottor; filr. 92 and hold the nodi-in portion of that layer down on the wrapper conveyor 20. The rod;-. 408 and 4-10 however in turnine to thoi.r vertically spaced po:-iti;:ns pull on the layers of filn 30 and ~j2 l'oming the filti into ;m opened-out tube as indicated in Figure 29. It is evident that with the forward end of tho tube thus opened out, it is possible to insert a roll R into the tube. It will, be clear therefore, that at the input end of the ur.chine, nnd indeed until the opening nechanisn. arrives at the wrapper conveyor 20, the finger operating i-echanisn 386 renaini; in the collapsed condition wheroir. ir occupies :i 3Ubst->nti-.lly fl it plane. At the wrapper conveyor however, the nech'TUdr. is activated to open out thj rods and so open the tube - 41 - 39067 i'fv- :;h.r Towards the end of the top run of the carrier 38, and after withdrawal of the pusher 452, the finder opening nechanisn 3806? raturru; to it3 original flat condition and c.'in then ooaily be withdrawn fron thu tube 170 as shown in tho right-hnnd end of Figure 3» The conploto package coopriaing tho filn 170 with the roll R inside it then passo3 through tho hont 5. uhrink tunnel 24 nnd this causcs the filn to shrink tightly on to the periphery of the roll R, and at the some tiao c;'.Ufios thu portions of the tube which project beyond thu oivl.-. of Hiroll to shrink inwnrdly, thus subatantinlly cloning thu "juia of thu p.'Ok., It is to bo understood that tho nnchine could be provided with end se-lors adaptod to operate on the unds of the tube 170 between the withdrawal of the opening flng^ru nnd the entry of tho p-'ck into the shrink tunnel. This would be necessnry, for example, if the article being •'rapped were of euch " nature that a. completely Bulled pack is required. - 43 - 3 9 0 0? AL'fb'ltWiiTlVE OPSNINu inferring now to Figuro 30, there is shewn an alternative tube opening nechnninn 500, which can bo provided or each of tho carriers 3?, in placo of tho finger opening aechnnisn 5 366 illustrated in Figures 15 and 20.

There nro longitudinal ly extending guide rods 50? r-.nd 504 similar to the rods 33^ -red 536, and those are aapportod it their ru.-.r ends ir> body nonbor 506 which takoa the plncc- of the body riombor 3/»0 in the previously described const.ruction. 10 In th i j nrrnnr,orient however, the body renbor L306hi.'J two uput-iMing wings 5^ nnd *>10 one :.t each aid., of th. body nenK.r, go thnt ther- in plenty of space- for tho roll R to p-aan therebetween.

A finder operating jlider nenber 512 h.u» bossoe which 15 are bored to receive the ijuide rods 502 and 504, .;o thnt the menbi r 512 is ali.i able lor.gi ladinnlly of tho carrier 38* in the 'lirtiction indicited f\y the arrows 514. On th.. !•.. '.ding fiide i>f the ;ilid- r -..r'bev i:i a projecting i.u^ 516, and pe^ 51B •'■xt. jv!:j \*l rfcir.al ly t.hraupdi thir. lug ■ u-i c:rri-') 20 cylindrical car. follower 520 <:t itrs lowvr ^nd. .'.'he follower 520 er.g.in the c.?.r track *'*26 (3..0 Figure 24) so that tho novcrient of the slider 51«? is controlled by the cmn track 426 iis ;x -ctlv the st-j nnnner is thj trunnion n.oRber 420 shotti'. in r'ifrui-c 15. ;ic.wev.;r, in the 07,1 ning 25 mc-ch'inism 500, th, slider Ce-siber 512 i:i r.ot used to eauae» rotnti on of the r.hnft, nnd therefore thcro i:; no necessity for the- pin 422 ,and helical groove ,=413 as described in tho previous construction.

Instead, the slider ufcrcbor 512 hns a pair of 30 upstanding wings rOc ari'l 524 each of which, carries a pivoted - 44 - 39067 bain 5«-6 fomod with n dinnutral hol^, through which jv'isaea u connecting rod 5'-b. The rear end of thu' rod 528 paoneo through n boss 530 fomed on nn arm 532 of a lifting nenbur 53^ which io pivoted on coaxial pins 536 supported by tho 5 - wings 508 and 5^0. The boss 530 is pinned to the rod 528 ' 'so that movdnont of tho rod 528 is always transmitted to the lifter aunbor 53*. A collar 538 is secured on to tho rod 528 by a grub screw (not shown) and a compression spring 5^0 surrounds the portion of tho rod 528 which extends botweon 10 the pivoted boss 526 nnd tho collar 538. Vhu-n tho slider auaber 5^2 moves rearwardly, duo to tho engaguount of tho follower 520 with a portion of the coo 426, notion is transmitted through tho boss 526 and the rod 528, to the liftor meober 53*, which in consoquoncc is turned through 15 an angle about the pivots 536. This upward swinging of the lifter aunbor 53*, is accommodated by rotation of tho boss 526 about its own axis on the respective wing 522 and 524. It will be appreciated, that the linear distance throup?a which the boss 526 is carried by tho member 512 is fixed, 20 fcy the ahapo of tho portion of the can 426, which produces this linear notion. On the other hand, the angle through which the liftor comber can turn is restricted by the .-iizo of the plastics tube which is being opened. Consequently, after the lifter number 53^ has been arrestud in its upward 25 movement, further rearward novenent of the boss 526 is accomodated by that boss sliding along the rod 528, coopressing the spring 5^0. On the return novo-nemont of the pusher raunber 5^2, the spring $40 expands, and returns the boss 526 to its original position relatively to the rod 528, 30 before the liftor number 5>4 begins to descend.

The liftor n^nber 53^ ttdfiprises a central bridge - 45 - 3 9 0 0 7 r hnvinr an arched portion ?4?. of a l'-rge encugh radius to ptrnit i roll If to p-^;n therethrough, this arched portion being supported on cranked nrcir. 544 jointod by l.it .-ml rii.cti'.'nu ryt6 to bvl'L-c ranked uectionn, which include the 5 hie 53?. The carrier also includcf. two fixed rod a 548 which are similar to th.j rods 406 in tho previously described finger op«niag ncchanisn.

In the norn.il inoperative position, the liftor laonbor 543 occupies the- position illustrated in Figuro 30, 10 where tho bridge li-r. in tho sane plane ns the- fixed rods 548, With the lifter nonber in this position, it ia possible for tho rear portion of the rods 54iJ and the lifter nenbor 534 to inter between the two la-era 80 and 92 of plastics filn it the input end of the n.-.chino. When a bag 170 ia forr'ed by tho ^5 sealing -and severing nuchonisn, the position is 03 illustrated in Figure 30, and at this stage, the pusher nonber 512 is noved re-arwnrdly, :'rxJ a:? a result of this, the arched portion y\2 of the* lifter ncnts.r pulls the- upper port of the tube- 170 away (ran tho lower r>^rt (which is retained by the 20 rods VvB) .and th- cranked portions 544 of tho lifter nonber hold the sides of the tube opon. It is then ponsibL. for the pur;her rochani.an, to push t:.. r-.'ll R intc the- tube at the sane tine .as thu. carrier 3? is boir.r retracted forwardly as described with reference to the previous 35 construction.

Tho liftor 534 is however r very effective nethod of opening the tube 170, and in particular, sine., even in its rais»xl position, t.h._ portions 5^4 :\r.; 31i 11 inclined rearwardly nnd upwardly, this n-.ano that th< lifter ia 50 gripping the tube iyO very tightly, and it ir, r.i/ij.ly unlik. iy that the tub-, can slip off the rodr, 'JAB :::vi U.e - 46 - 39067 lifter iKi.tx.x- iiurirur. the insertion of the roll R.

It is to b>. understood that a mchinc similar to thnt d«»cribed ubovu, can bo vjscd with filn which ia centru-foldod so that orily one nuch filn is required, fcho fold producing > the two layers. It io then necessary to ensure that the two layers ar>. opened fron onch other at tho opposite edge of the filn to the fold, when the filn is at tho input end of tho nachine to allow thu tube opening nechnnisn (which rviy bo that illustrated in PiguruS 15 and 20 or that illustrated in 10 Figure 30) to enter between the two layers. Aftor thi3, the two lnyers are brought into face-to-face relationship to pemit the rapid scaling nnd sevuring ope ret ion by tho filn feed conveyor 18 and the foed carriage 172, as provioualy dascribed. 15 It w3.1 be appreciated thnt it ia desirable to us<_- two layers of filn of thv sane width. However, it iH possible to use lay-.rs of dif feront widths, provided that the tube opening nechnnisn ia inserted between the two layers.

Clearly a nachine in accordance with the invention 20 can be to wrap i^ooda other than wallpaper, althou#j it will generally be ru.e .ssary to nodify the detailed coru-;truct L.~ of the machine. For .xa:.ple, if a ncn-cy." indrical article is to be wrapped, tr.. n it ray b-e necessary to provide a product conveyor of different shape to thnt shown in 25 Figures 15 to 20. In sore instances, tho carrier my have a flat bed with vertic al i*uide walls projecting upwardly thorefron. In another instance where cylindrical articles "• T-j to be wrapped, the- tray of the product carrier ia replaced by two parallel cylindrical rods on which the 30 article rests. Thin latter arrangenent pomits the pusher to be operated by fixed cans below the top run of the product - 47 - 3 9 0 C 7 conveyor J6, tho connection K. twem th<_ c^r. foil owor ard tho pusher pnnaing through th.- bo twoon tho two rods. Also, il' nrticloc of '• non-cylindrical nh*\pj - ro to bo wrnppod thv.n tho .irr.-inf^rvnt of tho tubc-opuning r.-.chmisr. will h-.vc to bo nltorud.

Claims (2)

1. WHAT I CLAIM 13:- 3 8 0 6 7 1. A method of forming a package, which includes the steps of continuously feeding two superposed layers of wrapping film through a scaling station at a preselected velocity; selecting the cycle frequency of a sealing device reciprocable along a path parallel to that of the fila feed, to determine the distance between transverse seals formed by the sealing device on the two layers of wrapping film, simultaneously selecting the cycle frequency of a film severing device to coincide with the frequency of th* sealing devico; selecting the stroke length of tha sealing devioe so that it truvols on its fox*ward stroke in Che same direction as the loyers of film at tho saao linear spued as the film; bringing the scaling dcvico into opor.itive relationship with the layers of film during at least part of its forward stroke in each cycle to produce a sealing together of the two fila layers transversely to the direction of the film feed, and operating the severing device ^aultuneously with the formation of the trunsvorse seal to auvcr tho film layers along a line extendi.nr across the width of the film layors und within the width of a seal formed by the sealing device to neparate a film package in advance of the line of sc'er from the following film.

2. A method of forming a package as claimed in Claim 1, in which the sealing device has a compound movement in ita forward traverse, including a movement perpendicular to and towards the path of the film feed but is maintained in a constant orientation relatively to the path of the fila throughout the cycle of the sealing device. - 49 - 39 0 6*7 3. A method of forming u package as claimed in either of Claims 1 and 2, in which the two layers of wrapping fila travel in a forward direction on a continuously moving conveyor. 4. A method of fording a package as claiaed in Claia 3, including gripping the two layers of file between the contixmously moving conveyor and a feed carriage reciprocable in unison with the sealing device, whereby the nip on the fila layers between the conveyor and the feed carriage travels in the direction of movement of the file, so that there io no relative movement between the nip and the layers of fila. 3- A method of forcing a package as claiaed in Claim 4, in which the sealing device is brought into the operative relationship with the layers of film during only a part of the forward movement of the feed carriage. 6. A mothod of forming a package as claimed ia Claim 4 or Claim v, in which the feed carriage is aaintained in engagement with the fila layers throughout i:s reciprocating cycle. 7. A method of forming a package us claimed in any one of Claims 1 to 6, which includes heating the sealing device at least during the period that the sealing device is brought into operative relationship with the wrapping film. 8. A method of forming a package as claimed in any one of Claims 1 to 7, in which after a package htia boon aevcred from tho following layers of fila, it is given a rapid forward movement relatively to tho forwurdly travelling film layer* to separate that package completely fron the following package. 3 9 0 V 7 9- A sealing mechanism for soaltng together two luyoro of wrapping film at longitudinally cpuced positions comprising truversing mean3 Tor traversing the two layers of film in a forward direction along a predetermined path; the traversing 5 means including o conveyor moving continuously in one direction and articulated holding aeons for nipping the two layers of film on to the conveyor; a mechanism for reciprocating tho holding means along a path parallel to the predetermined path and a driving mochunisa. for both the conveyor and the 10 holding means, this driving mechanism including a variable dovice for varying the cycle frequency of the rociprocable holding means relatively to the linear speed of the film; a scaling and severing dovice carried by the holding means and mechanism for bringing tho sealing ond sovoring davico 15 into operative reiation^liip with the film layers durir.g at least part of tho forward motion of the holding means. 10. A sealing mechanism as claimed in Claim 9. whoreia the driving mechanism incudes a first cam mechanism geared to the conveyor und adapted to produce reciprocation of the holding 20 means, a second cam lechanism geared to the conveyor and adapted to produce movement of the sealing device towards the conveyor during that part of the cycle of the holding means when the sealing device i3 required to carry out its sealing function. 25 11. A sealing mechanism as claimed in Claias 9 or Claix 10, in which the length of stroke of tho holding aeur.s is adjustable. - 51 - 3 9 0 6 7 1^. A sealing mechanism <*s claimed in Claim 11, in which the means Tor causing reciprocation of the holding moans comprises on oscillating motion transmitter of variable stroke length. 13* A sealing mechanism as claimed in any one of Claims 9 to 12, in which the holding means is arranged to romain in a constant orientation relatively to the path of movement of the layers of film. 14. A sealing mechanism as claiaed in any one of Claims 9 to 13, in which the holding neans comprises a carriage having a pair of rollers for engagement with the film. 15* A sealing mechanism as claimed in Claim 14, in which the rollers are each geared to an endless chain driven at a linear speed directly related to that of the conveyor. 16. A sealing mechanism as c" ^ined in Claim 14 or Claim 15, in which ut least one roller of the carriage ia arranged to be given a sudden rotation at the er.i cf the forward movement of the carriage, for the purpose of pulling a tube of film away from the following bulk of film. 17. A sealing mechanism as claimed in Claim cj, constructed, and arrangod to operate substantially as herein described, with reference to Figures 4 to 14 of the accompanying drawings. 18. A method of forming a package as clained in Claim 1, substantially as herein described with reference to Figures 4 to 14 of the accompanying drawings. F. R. KELLY ■£ CO. AGENTS FOR THE APPLICANTS.