Fusing packaging film

Abstract: Apparatus for use in fusing together the overlapping edges of a packaging film (b) wrapped around an article (a), including a support member (1) arranged to be located in an operative position between the said overlapping edges and the article (a) during the fusing operation; means for feeding the said support member to, and withdrawing it from, its said operative position, substantially along the line of the said overlapping edges; and a flexible separator sheet (4) arranged to be located between the said support member (1) and either the said overlapping edges or the article (a) during the fusing operation; the said separator sheet being connected to the support member in such manner that it is gradually peeled away from either the said overlapping edges or the article, towards the support member, as the support member is withdrawn from its operative position.

Description: This invention relates to an apparatus for use in fusing together the overlapping edges of a packaging film wrapped around an article, when both end portions of the film wrapped around the article in a tensioned state are overlapped and then fused together. In such an operation it is known for a support member, having at least the same length as that portion of the film which is to be fused, to be placed between the surface of the article and the overlapped portions of the film, as a backing support for a pressurizing member which is pressed against the support member so as to heat and fuse the overlapped portions of the film. However, when the support member is taken out of the fusion-processing position after the fusing operation, it tends to scratch the outer surface of the article and/or the inner surface of the fused portion of the film, due to friction, thus causing damage to the film or to the surface of the article. In particular, cutting damage frequently occurs in the film due to shrinkage of the film. Conventionally, a member with a smooth surface having substantially the same length as the width of the film is used as the support member and the support member is usually fed into and withdrawn from the fusion-processing position. However, as already mentioned, damage can occur to the film or to the article being wrapped, due to friction between the said support member and the film or the article when the support member is being fed in or withdrawn, and it can also be inconvenient that a considerable amount of space is required for feeding and withdrawing the support member to and from the fusion-processing position, particularly in the case of a relatively long support member. An example of the prior art is GB-A-1301353 which discloses the preamble of claim 1. Accordingly the present invention is characterised in that a flexible separator sheet is arranged to be located between the said support member and either the said overlapping edges or the article during the fusing operation; the said separator sheet being connected to the support member in such manner that it is gradually peeled away from either the said overlapping edges or the article, towards the support member, as the support member is withdrawn from its operative position. In use of such an apparatus, before overlapping the end portions of a film wound in a tensioned state around an article, the support member is fed to a fusion-processing position, and at this time, a smooth separator sheet made of an appropriate material is successively advanced to cover the surface of the support member which provides the supporting surface during the fusing operation, from the leading end of the surface. The end portions of the film to be fused are now overlapped on the surface of the support member separated therefrom by the sheet member. The overlapped portions are then pressed against the support member by a pressing member, thereby fusing the overlapped end portions of the film by means of heat provided by a fusing die member provided at the surface of the support member. Then, when the support member is withdrawn from the fusion-processing position, the sheet member placed between the support member and the fused portion of the film is also withdrawn by being gradually peeled away from an inner surface of the film, with the result that the support member does not contact the surface of the film, which now envelopes the article in a shrunken state, and thus damage to the film surface caused by friction between it and the support member is prevented. If desired, a separator sheet member may also (or alternatively) be placed between a rear surface of the support member and the surface of the article, in the same manner as described above. Then, when the support member is fed in, such a sheet member is caused to engage gradually, starting at the leading end thereof, with the rear surface of the support member. Then when the support member is withdrawn, the sheet member is peeled away gradually from the surface of the article. Consequently, both the inner surface of the film and the outer surface of the article can be prevented from being damaged by friction between those surfaces and the support member during the feeding and withdrawing movements of the support member. The support member may be a flexible member, preferably in the form of a chain of short elements. This has the advantage of enabling the support member to be fed to and withdrawn from a fusing location in a direction differing from the plane of the fused portions of the film, by turning it through an angle during such movement. Thus a standby position of the support member can be freely selected. Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:- Fig. 1 is a side elevational view of apparatus of a first embodiment, having a separator sheet which contracts only one surface of a support member; Fig. 2 is a front elevational view of the apparatus as shown in Fig. 1; Fig. 3 is a top plan view of the apparatus as shown in Fig.1; Fig. 4 is a side elevational view of apparatus of a second embodiment, provided with separator sheets at both the front side and the rear side of the support member; Figs. 5A and 5B are side elevational the manner of feeding in and withdrawing a separator sheet; Fig. 6 is a side elevational view of apparatus of a third embodiment, in which a separator sheet extends through the support member; Fig. 7 is a side elevational view of apparatus of a fourth embodiment, similar to the embodiment of Fig. 6 but with separator sheets on both sides of the support member; of Fig. 8 is a partial side elevational view apparatus of a fifth embodiment, provided with a separator sheet only at the front side of a flexible support member; Fig. 9 is a partial side elevational view of apparatus of a sixth embodiment, similar to the embodiment of Fig. 8 but provided with separator sheets at the front and rear sides of the flexible support member; of Fig. 10 is a side elevational view of apparatu a seventh embodiment, provided with a separator sheet only at the front side of a flexible support member; Fig. 11 is a side elevational view of apparatus of an eighth embodiment, similar to the embodiment of Fig. 10 but provided with separator sheets at the front and rear sides of a flexible support member; Fig. 12 is a front elevational view of part of a flexible support member; Fig. 13 is a side elevational view of the flexible support member as shown in Fig. 12; and Fig. 14 is a cross-sectional view taken along the line XIV-XIV of Fig 12. Figs. 1 to 3 illustrate a first embodiment of the present invention, wherein a separator sheet 4 is provided on a surface of a support member 1 for a fusing operation, i.e. a supporting surface 1a for the overlapped end portions of a stretchable and shrinkable packaging resin film b wound around an article a in a tensioned state. As shown in Fig. 3, the packaging film b is pulled out from winding rollers at both sides, wound around three surfaces of the article a, and held in that position. Prior to the fusing operation for the film end portions in that position, the support member 1 for the fusing operation is moved in along the surface of the article a on which the film b is not wound, in a direction along the intended fused adhesion line of the film, i.e. from above the article a in Fig. 1, with its rear surface 1b adjacent the article. The support member 1 is fed in by a feeding and withdrawing device 2 such as a piston and cylinder mechanism or a winding and releasing mechanism, and its leading end is engaged, when necessary, with an holding mechanism 3 to hold it stationary. Then, the film b at both sides of the said surface of the article is pressed in and held against the side surfaces of the support member 1 at a specified position by movable bars c as shown by an imaginary line in Fig. 3. The film is now cut by a suitable mechanism (not shown), its cut ends b' are overlapped on each other on the supporting surface 1a of the supporting member 1, and the overlapped portions of the film are heated and fused together by contact pressure between a fusing die member 1c provided on the supporting surface 1a and a movable pressing member d. As the support member 1 is advanced into the fusion-processing position, a smooth separator sheet member 4 having one of its ends 4a fixed in position to one side of the support member 1 and its other end 4b secured to the leading end of the support member, is gradually advanced from a standby position shown in Fig. 1 by a solid line to fusion-processing position shown by a ghost line, so as gradually to cover the supporting surface 1a, starting from its leading end, as the support member 1 is moved downwards. Fusion is then performed as described above, by overlapping the film end portions b' on the supporting surface 1a. In the illustrated example in which the fusing die member 1c of the support member 1 is arranged at a central part of the supporting surface 1a, two such sheet members 4 are arranged one on each side of the fusing die member 1c. In this embodiment, fusing means in the form of a fusing die member 1c having an appropriate shape is provided on the support member 1 and a flat plate-like pressing member d is arranged for heating and pressing against the fusing die member 1c. Alternatively, however, a heating member may be provided on the support member 1 and a fusing die member having any desired shape may be provided on the pressing member d which can be moved towards the support member 1. The die form of the fusing die member 1c may be a zig-zag fusing line as shown in Fig. 12 or of any other desired form; in particular, if the fusing die member is made of a resilient material such as heat-resistant rubber, then a fusing die of any desired shape can easily be made and its resiliency can be effectively used for press fitting it in place. After completion of the overlapping and fusing operation on the end portions b' of the film b, the pressing member d is retracted and the support member 1 is withdrawn from the fusion-processing position by the feeding and withdrawing device 2. At the same time the sheet member 4 is drawn out together with the support member 1 by being gradually peeled off from the inside surface of the film b; thus the support member 1 is easily pulled out without sliding along the inside surface of the film b, due to the presence of the sheet member 4. Even if the film b tends to cling to the article a due to its shrinkage and tension, the support member 1 will still not make direct contact with the inside surface of the film, due to the presence of the sheet member 4. Further, since the sheet member 4 is gradually peeled away from the inside surface of the film, damage to the film caused by mutual friction is positively prevented. In this embodiment, in which a sheet member 4 is provided only on the front surface of the support member 1, in order to achieve smooth feeding and withdrawal of the support member, freely rotatable small-diameter rollers 5 are mounted on the rear surface of the support member 1, as shown in Fig.1, and these rollers rotate on the surface of the article a so as to facilitate feeding and withdrawal of the support member. In addition, in order to ensure the prevention of damage to the article during the feeding and withdrawal of the support member 1, a further separator sheet member 4' may be provided at the rear side of the support member 1, as shown in Fig. 4, in the same manner as described above. The manner in which, during feeding and withdrawal of the support member 1, the sheet member 4 is advanced along the surface of the support member and is peeled away from the inner surface of the fused film b, is illustrated in Figs. 5A and 5B respectively. Reference numeral 6 in the figures denotes a transfer conveyor for the articles a. Fig.6 illustrates another embodiment. In this embodiment a sheet member 4 having one end 4a fixed in position is inserted into the support member 1 around a small diameter roller 7 at the leading end of the support member. The sheet member 4 then passes longitudinally through the support member and out of the other end thereof, and has its other end connected to a feeding device 8. In this case, the sheet member 4 is wound up by the feeding device 8 while the support member 1 is being withdrawn by the feeding and withdrawing device 2 from the fusion processing position shown by ghost lines in this figure to the standby position indicated by solid lines. Thus, as the support member 1 is being advanced to the fusion-processing position at the front surface of the article a, the sheet member 4 is unwound from the feeding device 8 simultaneously, so that the sheet member is fed out while being moved along the supporting surface 1a of the support member 1 as the support member is moved downwardly. At this time, the rear surface of the support member contacts the article by way of the rollers 5. Then, when the fusing operation is completed and the sheet member 4 is being wound up by the feeding device 8 while the support member 1 is being lifted upwards, the sheet member is peeled away from the inside surface of the film b and thus the film surface is not damaged by friction with the support member. As shown in Fig. 7, if a further sheet member 4' is provided at a rear surface of the support member 1 in the same manner as with the front surface, damage to the surface of the article caused by friction with the support member can be prevented. In the above described embodiments a rigid plate member having a length greater than the width of the film is used as the support member 1. In this case, as shown in Figs. 1 and 4, in order to pull out the sheet member 4 to the standby position, the support member 1 must be withdrawn substantially three times as much as its length, and the space required for that operation is necessarily restricted by the surrounding conditions. In the case of Figs. 6 and 7 in which the sheet member 4 extends through the support member 1, the necessary travel of the support member is reduced. However, the direction of movement of the support member is still restricted to a plane containing the fused adhesion line, and this restriction on the direction of movement of the support member is a disadvantage, particularly in the packaging of relatively large-sized articles. Referring now to Fig. 8 and subsequent figures, some embodiments of the invention in which the support member 1 is made flexible, in order to reduce the above-mentioned disadvantages, will be described. Thus in these embodiments the support member 1 is made up of a plurality of short member 1' whose front surfaces are used as a supporting surface 1a during the fusing operation. The short members are connected in series by means of chains 9 so as to have a length greater than the width of the film b. In the case of Fig. 8, the sheet member 4 extends along the front surface of the chained support member 1 and rollers 5 of small diameter are provided on the rear surface of the support member. Fig. 9 illustrates an embodiment in which sheet members 4 and 4' are provided at both the front and rear sides of the support member 1. In both of these cases, the chains 9 having the short members 1' connected thereto extend around a star-shaped guide wheel 10, thereby deflecting the feeding and withdrawal direction of the support member 1 at an angle of 90° with respect to the line of fusion. Thus the withdrawal direction of the support member 1 is changed to a horizontal direction with respect to the vertically extending fused adhesion line in the illustrated example. The rear ends of the chains 9 are connected to a carriage 13 which is connected to a moving belt or a chain 12 which is drivable in either direction by a motor 11. The chained support member 1 can thus be fed and withdrawn by movement of the carriage 13 between a standby position indicated by solid lines and the fusion-processing position, located at the front surface of the article a, shown in ghost lines in each of these figures. Further, a sheet member 4 is provided with one of its ends 4a fixed in position and the other end 4b secured to the leading end of the chained support member 1, in the same manner as in Figs. 1 and 2. Therefore, along with feeding and withdrawal movement of the support member 1, when the support member is fed in, the sheet member 4 is located along the supporting surface 1a, whilst when the support member is withdrawn the sheet member is rolled up while it is being peeled away from the inside surface of the film b. If a further sheet member 4' is arranged at the rear surface of the support members friction between the chained support member 1 and the article a is also prevented during feeding and withdrawal the support member. In these figures, reference numerals 14 and 14' denote supporting wheels for the sheet members 4 and 4'. Reference numeral 15 denotes a support plate for supporting the chained support member 1 at its standby position. Figs. 10 and 11 show embodiments in which, in order eliminate a disadvantage in the embodiments of Figs. 8 and 9 that the distance by which the chained support member 1 must be withdrawn in order to withdraw the sheet members 4 and 4' to their standby positions is undesirably large, the sheet members 4 and 4' are arranged to extend through the chained support member 1. In this case, the feeding and withdrawal distance of the chained support member 1 is thus reduced in the same manner as in the embodiments shown in Figs. 6 and 7. Fig, 10 illustrates a case in which the sheet member 4 is arranged only at the supporting surface 1a of the support member 1, one end 4a of the sheet member being fixed in position and the sheet member passing over a small diameter roller 7 at the leading end of the support member 1 and then passing through the short members 1' in sequence, whereafter the sheet member 4 passes out of the other end of the support member 1 and its terminal end 4b is fixed in the position. Between the fixed terminal end 4b and the rear end of the support member 1 the sheet member passes around a wheel 16 rotatably supported on the carriage 13. Thus the sheet member 4 is fed and withdrawn with respect to the fusion-processing position together with the support member 1 connected to the carriage 13 by the chains 9, and in response to an amount of movement of the carriage 13 which is relatively short and equivalent to movement of the support member 1. Referring now to Figs. 11 to 14, an embodiment in which both the front and rear surfaces of the chained support member 1 are provided with the sheet members 4 and 4' will be described. Each of the short members 1' constituting the chained support member 1 is comprised of a front piece 20 and a rear piece 21, as shown in Fig. 14. An appropriate number of such pieces are connected by a pair of chains 9 arranged one on each side of the rear of each of the front pieces 20. An auxiliary short member 1'' is connected to the end piece so that together they form a freely flexible chained support member 1. One end 9a of each chain 9 is connected to the auxiliary short piece 1'' and the other end 9b thereof is connected to the carriage 13. As the carriage 13 is moved, the chained support member 1 is fed and withdrawn with respect to the fusion-processing position at the front surface of the article a. Each of the rear pieces 21 is integrally fixed to a respective front piece 20 by way of the chains 9. A surface of each of the front pieces 20 is provided with a fusing die member 1c for use in fusing the film. A continuous fused adhesion line of a predetermined length is thus formed by all of the short members 1' together. In this case, in order to prevent the fused adhesion line from having gaps therein, it is preferable that the connecting portions of the short members 1' are such that there is no clearance between them. However, it would also be possible to use a long die member of resilient material fixed to the chained support member 1, instead of providing each short member with a fusing die member. In addition, both sides of each front piece 20 are formed with recesses 22 having an appropriate shape. As already illustrated in Fig. 3, the film b wound around the article a is pressed and held against the sides of the support member 1 by movable bars c. When both of the cut end portions b' of the film b are overlapped on the surface of the chained support member, the movable bars c are received in the recesses 22, and the short members 1' are pressed and held by the movable bars c so as to be held at their front, rear, right and left sides. A deformation caused by the chained condition is thereby prevented, by placing all the short members 1' in an integrally fixed condition. Thus, accurate alignment of the fused adhesion line is achieved. Further, when the chained support member 1 is fed into the fusion-processing position, a holding device 3 advanced by either a solenoid or a cylinder mechanism is thrust into an engaging hole 23 of the auxiliary short member 1'' and the support member 1 is thus positively kept stationary. Each of the ends 4a of the sheet members 4 and 4' at the respective front and rear surfaces of the chained support member 1 (front sheet members 4 are two in number) is fixed in position. The front sheet members 4 are received in clearances 24 formed at each side of the rear of each of the front pieces 20, and the rear sheet member 4' is passed through an inner surface of the rear piece 21. Thereafter, they both extend out of the rear end of the support member 1, and the other ends 4b of the sheet members are fixed in position. The sheet members 4 and 4', between the fixed ends 4b thereof and the rear end of the support member 1 pass around wheels 16 and 16' rotatably supported on the moving carriage 13. The sheet members are fed and withdrawn with respect to the fusion-processing position at the front of the article a, together with the support member 1, as the wheels 16 and 16' are moved, in the same way as in the previous embodiments. The sheet members 4 at the front and rear surfaces of the front piece 20 of each of the short members 1' are provided with a longitudinal projection 25 on their surfaces contacting the front piece 20, while the sheet member 4' at the rear surface of the rear piece 21 is provided with another longitudinal projection 25 on its surface contacting the rear piece 21. These projections fit into recesses 26 formed in the front piece 20 and the rear piece 21 respectively, so as to prevent displacement of the sheet members 4 and 4', whereby their feeding and withdrawal operation is reliably carried out. In each of the above described embodiments, the feeding and withdrawal of the support member 1 is in a vertical direction because the film b wrapped around the article a is fused along a vertical fused adhesion line. However, if the fused adhesion line were to be set in a horizontal direction the feeding and withdrawal of the support member 1 could be set in a horizontal direction accordingly. It will thus be seen that, at least in preferred forms of the present invention, when a support member for the overlapped end portions of a packaging film wrapped around an article to be packaged is fed in and withdrawn from the fusion-processing position, a smooth separator sheet member is interposed between the supporting surface of the support member and the film and/or between the supporting surface of the support member and the surface of the article, at the front and/or rear portions of the support member, so that friction between the support member and the film and/or the article can be eliminated. In particular, after the fusing operation, even though the film is apt to cling to the support member due to its shrinkage, whereby withdrawal of the support member becomes difficult, the present invention provides for easy withdrawal of the support member and furthermore prevents the film and/or the article from being damaged, due to the fact that the separator member is gradually peeled away from the inner surface of the film and/or the article. Furthermore, if a freely bendable chained support member is provided by interconnecting a plurality of short members, the support member can be fed in and withdrawn with respect to the fusion-processing position in a direction which is not limited to a plane containing the fused adhesion line of the film, thereby reducing the feeding and withdrawal space needed for the support member.

Claims: Apparatus for use in fusing together the overlapping edges of a packaging film wrapped around an article (a), including a support member (1) arranged to be located in an operative position between the said overlapping edges and the article (a) during the fusing operation; means (2,13) for feeding the said support member (1) to, and withdrawing it from, its said operative position, substantially along the line of the said overlapping edges; characterised in that a flexible separator sheet (4) is arranged to be located between the said support member (1) and either the said overlapping edges or the article (a) during the fusing operation; the said separator sheet (4) being connected to the support member (1) in such manner that it is gradually peeled away from either the said overlapping edges or the article (a), towards the support member (1), as the support member (1) is withdrawn from its operative position. Apparatus as claimed in claim 1, wherein the said separator sheet (4) is arranged to be located between the said support member (1) and the said overlapping edges during the fusing operation. Apparatus as claimed in claim 2, including a second said separator sheet (4') arranged to be located between the said support member (1) and the said article (a) during the fusing operation. Apparatus as claimed in any of claims 1 to 3, wherein the said support member (1) is a substantially straight rigid member. Apparatus as claimed in any of claims 1 to 3, wherein the said support member (1) is a flexible member. Apparatus as claimed in claim 5, wherein the said support member (1) comprises a chain of short members (1'). Apparatus as claimed in claim 5 or 6, wherein the path of movement of the support member (1) to and from its said operative position turns through an angle adjacent the fusing station. Apparatus as claimed in claim 7, wherein the said angle is approximately 90°, whereby when the support member (1) is in its withdrawn position it extends substantially perpendicularly to the line of the said overlapping edges. Apparatus as claimed in any preceding claim, wherein one end of the or each said separator sheet (4,4') is fixed in position and the other end is connected to the leading end of the support member (1). Apparatus as claimed in any of claims 1 to 8, wherein the or each said separator sheet (4,4') extends longitudinally and movably through the said support member (1) between its ends. Apparatus as claimed in claim 10, wherein one end of the or each said separator sheet (4,4') is fixed in position and the other end is connected to take-up means. Apparatus as claimed in claim 10, wherein both ends of the or each said separator sheet (4,4') are fixed in position.

Inventors: SAITO TSUTOMU, SAITO, TSUTOMU
Applicants: SAITO TSUTOMU, SAITO, TSUTOMU
Application year: 1990
Main classification: B65B9
IPC codes: B65B51, B29C65, B65B11, B65B53, B65B9