NZ197060A

NZ197060A - Forming chain of rib edged bags

Info

Publication number: NZ197060A
Application number: NZ19706081A
Authority: NZ
Inventors: N E Claxton; D H Youngman
Original assignee: Stripform Packaging
Priority date: 1981-05-11
Filing date: 1981-05-11
Publication date: 1984-05-31

Description

FORK 5. S.9., # Fee: $55.00 NEW ZEALAND V' »» • • • « • • < • • • • •• • • • • • • • • • • • • • • • • « • • • < »• •• ; Priority Dafcs-i^ ■ ■ * .. < Complete SpaoHicstion Filed: | .Class: -oblicatscn Date: * • ■ ■ ■ >ublicatscn I P.O. fcSo: I ?•. §.&. J Insert number of Provisional Specification(s) (if anv) and da t e(s) of fi Ling; otherwise leave blank.

PATENTS ACT 195 3 Number: Date: COMPLETE SPECIFICATION II * Insert Title of Invention.

Insert full name, full street address and nationality of (each) applicant.

Lx •PRODUCTION OF PLASTIC BAGS AND SACHETS' ZVWE STRIPFORM PACKAGING (PROPRIETARY) LIMITED, A company organised with limited liability in accordance with the laws of the Republic of South Africa of 9th Floor, Barclays Bank Building, Heerengracht, Cape Town, Cape Province, Republic of South Africa. hereby declare the invention for which i/we pray that a patent may be granted to n%6/us and the method by which it is to be performed, to be particularly described in and by the following statement- Indicate if following page is numbered '1(a)' 1.5.80 197060 This invention relates to the formation of bags of synthetic plastics material film. More particularly, this invention relates to a method of and an appratus for use in forming an elongated web of bags which are separable from the web.

In the specification, the term 'bags' is intended to include bags, sachets, pockets, and the like.

A bag of synthetic plastics material film is known which is sealed or closed along three sides and has its fourth side open to define a mouth for the bag. The bag has complementary engagement rib formations along the inner surface of the walls defining the mouth of the bag, to allow the rib formations to be engaged by the application of finger pressure to seal off the mouth of the bag.

Such bags are generally manufactured by an extrusion process in which synthetic plastics material film is extruded as a web with the complementary engagement rib formations extending down the length of the web adjacent the opposed elongated edges of the web. The web is then folded along its length to bring the complementary engagement rib formations into register with each other, whereafter the opposed walls of the web can be sealed together across the web at spaced intervals along the length of the web to define the separate bags, and the web can then be severed in the sealed zones to provide the separate bags. 197060 Developments in the marketing of particulate material and the like in bags of the kind described, have called for the supply of such bags in elongated web form where the bags can be separated from the web. In such elongated web form, the bags can be more easily loaded mechanically with particulate material or other material. In addition, in elongated web form, the provision of mass printing of suitable information on the side or sides of the bags, is facilitated.

The applicant is aware of attempts which have been made to provide such elongated webs by providing tear lines in the form of perforation lines in the web along which individual bags can be separated from the web when required.

Because of the thickness of the rib formations relatively to the remainder of the web, more heat is required to effect sealing of the rib formation between the individual bags than is required to weld the walls of the web together. In addition, because of the thickness of the rib formations, when perforations are provided through the web and the rib formations, when a bag is separated from the web, jagged edges will occur where the rib formations of a bag are separated from the remainder of the web. Not only are such jagged edges unsightly, but they tend to catch on clothing, textile materials and the like during use.

According to one aspect of this invention there is provided a method of forming an elongated web of bags which are separable from the web, which 1 97060. includes the steps of providing an elongated double walled web of synthetic plastics material film each of the two walls of the web including a respective rib formation, which rib formations extend along the walls adjacent one elongated edge of the web, and which rib 5 formations are adapted to interengage thereby releasably to secure said two walls to one another, heating the web in the region of the rib formations in separation zones at spaced intervals along the length of the web, flattening the rib formations in the separation zones, welding the walls of the web together in weld bands which extend across the web 10 in register with the separation zones to divide the web into bags, and forming lines of weakening in the weld bands to allow bags to be separated from the web along the lines of weakening.

The walls of the web may be sealed together along the elongated edge of 15 the web opposed to the edge along which the rib formations are provided. Alternatively, the walls may be integral along this elongated edge by forming the web out of a film which is folded along its length.

The engagement rib formations may be attached to the walls of the web by 20 any conventional means, or may be integrally formed with the web during extrusion of the web.

The complementary engagement rib formations may be of any conventional type. Thus, for example, the complementary engagement rib formations 25 may comprise a single elongated rib on the one wall, and a pair of ftOL PATENT OfftCE ! 19 JAN 1984 R5CEiV£D r 197060 laterally spaced elongated ribs on the other wall, with the spacing between the pair of ribs being appropriate to accommodate the single rib in a friction fit.

In this example of the invention, to improve engagement between the engagement rib formations, the single rib may be of circular or elliptical cross section, or may have a taper towards its base, with the pair of ribs being shaped to define a space of complementary shape between them.

In an onbodiment of the invention, the web in the region of the rib formations may be heated by means of hot air jets, by means of heated rollers or skids, or by means of ultra sonic energy waves.

In an embodiment of the invention, where the web in the region of the rib formations is heated by means of ultra sonic energy waves, the step of flattening the rib formations may be carried out simultaneously with the step of heating the web in the region of the rib formations by applying a flattening anvil to the rib formations at the same time as they are heated.

In an alternative embodiment of the invention, the rib formations may be flattened by applying a pair of heated flattening bars to the rib formations to squash the rib formations between the heated bars.

B4Z. PATENT OFFICE 19 JAN 1984 197060 In an embodiment of the invention, a pair of cold flattening bars may be applied to the rib formations after the web in the region of the ribs has been flattened by the heated flattening bars.

Conveniently, the rib formations may be flattened so that the flattened rib formations have a thickness approaching the thickness of the double walls of the web.

In one embodiment of the invention, the steps of welding- the walls together in the weld bands and forming the lines of weakening may be carried out simultaneously.

In an alternative embodiment of the invention, the step of forming the lines of weakening may be carried out before the step of welding the walls together in the weld bands.

The lines of weakening may be provided by score lines, lines of perforations, or the like.

The method may be carried out by advancing the web stepwise, and by carrying out the steps of the method in a cyclic manner at stations which are suitably spaced along the path of movement of the web.

The method may include the step of applying printing to the web in zones in register with the bags. - 6 N.Z. PATENT OFF I 19 JAN 1984 o 197060 According to another aspect of the invention there is provided apparatus for use in forming an elongated web of bags which are separable from the web, from an elongated double walled web of synthetic plastics material film each of the two walls of the web including a respective rib formation, which rib formations extend along the walls adjacent one elongated edge of the web and which rib formations are adapted to interengage thereby releasably to secure said two walls to one another and comprising heating means for heating the web in the region of the rib formations in separation zones at spaced intervals along the length of the web, flattening means for flattening the rib formations in the separation zones, welding means for welding the walls of the web together in weld bands which extend across the web in register with the separation zones to divide the web into bags, and weakening means for forming lines of weakening in the weld bands to allow bags to be separated from the web along the lines of weakening.

In an embodiment of the invention, the heating means may comprise heated nozzles which serve to direct hot air jets onto the web in the region of the rib formations or nozzles and to a source of hot air, said source bing connected to said nozzles which serve to direct hot air jets onto the web in the region of the rib formations.

In an alternative embodiment of the invention, the heating means may comprise heated rollers or heated skids which can be applied to the web 19/060 in the region of the rib formations.

In yet a further alternative embodiment of the invention, the heating means may comprise ultra sonic energy generation means for directing 5 ultra sonic waves onto the web in the region of the rib formations.

In this embodiment of the invention, the flattening means may comprise a pair of displaceable flattening anvils which are associated with the heating means and are displaceable to flatten the rib formations between 10 them at the same time as the web in the region of the rib formations are heated.

In an alternative embodiment of the invention, the flattening means may comprise a pair of hot flattening bars which are adapted to be heated 15 and are adapted to be displaced towards each other onto the web in the region of the rib formations to flatten them.

The flattening means may include a pair of cold displaceable clamping bars which are displaceable towards each other to clamp the flattened 20 portions of the rib formations.

In an embodiment of the invention, the welding means may comprise a pair of weld bars which are adapted to be heated and are adapted to be displaced towards each other with the web between them. _ 8 - I - OFF ICE 19 JAN 1984 j 1970.60 The weakening means may conveniently comprise a perforation bar having perforating teeth at spaced intervals along its length, which is adapted to be displaced onto the web to pinch the web between it and a support member of yieldable material, to perforate the web.

The support member of yieldable material may conveniently be of rubber or the like, which can receive the perforating teeth to allow them to penetrate the web during use.

In an embodiment of the invention, the welding means and the weakening means may constitute a single unit to allow welding and weakening to be performed simultaeously.

The apparatus may include advancing means for advancing the web through 15 the apparatus, control means for cyclically controlling operation of the heating means, and driving means for cyclically driving the flattening means, the welding means and the weakening means.

In an embodiment of the invention, the advancing means may be adapted to 20 advance the web stepwise, the control means may control the heating means so that it is operative only when the web is stationary, and the driving means may be adapted to drive the flattening means, the welding means and the weakening means so that they are operative while the web is stationary. 19 JAN 1984 197060 In an alternative embodiment of the invention, the advancing means may be adapted to advance the web continuously through the apparatus.

In this embodiment of the invention, the control means may control the 5 heating means so that the heating means is advanced cyclically with the web while heating the web in the region of the rib formations, and is then successively returned for heating the web in the region of the rib formations in each succeeding separation zone.

Further, in this embodiment of the invention, the driving means is adapted to drive the flattening means, the welding means, and the weakening means cyclically so that the advance with the web during operation and are then successively cyclically returned for subsequent operations.

In an alternative embodiment of the invention, the apparatus may comprise a rotatable drum over which the web is to pass, with the drum having at appropriately spaced intervals around its periphery, a series of composite stations for treating the web.

In this embodiment of the invention, each station may incorporate flattening means for flattening the rib formations, welding means for welding the walls of the web together in weld bands and weakening means for forming lines of weakening in the weld bands, which are adapted to 25 be operated in turn during passage of the web over the drum so that at - 10 - | N.Z. PATENT OFFICE 19 JAN 1984 RECEIVED 1 97060 each composite station, the flattening means will first be operated to flatten the rib formations, whereafter the welding means will be operated to weld the walls of the web together in weld bands, whereafter the weakening means will be operated to form lines of weakening in the 5 weld bands.

In this enbodiment of the invention, the heating means may be applied to the web in appropriate separation zones as the web is advanced towards the drum. Alternatively, if desired, each composite station may further 10 include heating means which is adapted to be controlled to operate in the appropriate sequence.

In this embodiment of the invention, the apparatus may include an endless pressure belt to compress the web against the periphery of the 15 drum as the web passes over the drum, and to ensure that slippage between the web and the drum is limited if not eliminated entirely.

The apparatus may include printing means for providing printing on the web in zones in register with the bags of the web.

In an embodiment of the invention, the apparatus may include folding means provided at the leading end of the apparatus to fold a flat web along its length to form the double walled web. In this embodiment of the invention, the apparatus will include engaging means to engage the 25 complementary engagement rib formations prior to heating of the web in ~ 11 ~ P N.Z. PATENT OFFICE 19 JAN 1984 P^c~rwn> 197060 the region of the rib formations.

If desired, the apparatus of this invention may be provided in line with extrusion means for forming the extruded web having the engagement rib 5 formations intergrally formed therewith.

The invention further extends to an elongated web of bags which are separable from the web, whenever formed by the method and/or means of the apparatus as described herein.

The invention further extends to a bag whenever separated from an elongaated web as described herein.

It will be appreciated that the web of this invention may be formed out 15 of any suitable conventional synthetic plastics material.

Embodiments of the invention are now described by way of example only with reference to the accompanying drawings.

In the drawings Figure 1 shows a fragmentary, diagrammatic view of one embodiment of the steps involved in carrying out the invention; and Figure 2 shows a fragmentary, diagrammatic view of an alternative - 12 - ■; ■ v-ft ^'■Z. PATENT OFF ICE 19JANW84 : Receivsc 1 197060 embodiment of the steps involved in carrying out the invention.

With reference to Figure 1 of the drawings, reference numeral 10 refers generally to an elgonated web of synthetic plastics material film which 5 has been folded along a foldline 12, marginally spaced from the elongated axis of the web 10, to provide two opposed walls 14.1 and 14.2 which have marginally differing lengths to facilitate separation of the walls 14.1 and 14.2.

The web 10 is formed by extrusion and has complementary engagement rib formations integrally formed therewith during extrusion, with the rib formations extending along the length of the web.

The rib formations are positioned so that when the web has been folded 15 along the foldline 12, the complementary engagement rib formations 16 of the opposed walls 14.1 and 14.2, are in register.

Prior to treating the web in accordance with this invention, the complementary engagement rib formations 16 are pressed into engagement 20 with each other.

Reference numeral 18 refers generally to apparatus for use in forming the elongated web 10 into bags 20 which are separable from the web 10.

The apparatus 18 comprises heating means 22 for heating the rib PATENT OFFICE 19 JAN 1984 1 97 06U forinations 16 in separation zones 24 at spaced intervals along the length of the web 10.

The heating means 22 comprises a pair of opposed air nozzles 26 which are heated or comprises nozzles connected to a source of heated air. In either form the nozzles direct a stream of heated air onto the rib formations 16 for heating them.

The apparatus 18 further includes flattening means comprising a pair of hot flattening bars 28 which are adapted to be heated and are adapted to be displaced towards each other onto the rib formations 16 to flatten them between the flattening bars 28.

The apparatus includes further flattening means comprising a pair of cold clamping bars 29 which are adapted to be displaced towards each other to clamp the flattened portions of the rib formations 16 between them.

The apparatus includes welding means comprising a pair of opposed, heated, weld bars 30 which are adapted to be heated and are adapted to be displaced towards each other onto the web 10 to form welds in regions herein termed weld bands 32 which extend across the web 10 and across the flattened portions of the rib formations 16 in register with the separation zones 24 to divide the web into the bags 20. |—^.2. PATENT OFFICE : 1.9JANW84 I 197060 The apparatus further includes a pair of opposed cold clamping members 34 which are adapted to be displaced towards each other to clamp the weld bands 32.

The apparatus further includes weakening means comprising a perforation bar 36 having perforating teeth 38 at spaced intervals along its length, which is adapted to be displaced onto the web 10 to pinch the web 10 between it and a support member 40 of yieldable material, to allow the perforating teeth 38 to perforate the web 10 along the weld bands 32.

The apparatus 18 includes advancing means (not shown) for advancing the web 10 stepwise through the apparatus.

The apparatus 18 further includes control means (not shown) for 15 cyclically controlling the heating means so that it is operative only when the web is stationary.

The apparatus 18 further includes driving means (not shown) for cyclically driving the flattening bars 28, clamping bars 29, weld bars 20 30, clamping members 34, and perforation bar 36 so that they are only operative while the web is stationary.

It will be noted that the various stations of the apparatus are equally spaced corresponding to the spacing between the weld bands 32 and thus 25 the opposed edges of the bags 20, except that a rest zone is provided Patent office 19 JAN 1984 197060 between the clamping members 34 and the perforation bar 36 to allow the web 10 in the weld bands 32 to cool sufficiently prior to perforation.

After the elongated web has been formed, individual bags 20 can be 5 separated from the web along the perforation lines 42.

If desired, the perforating teeth 38 of the perforation bar 36 may be arranged in the zone of the flattened rib formations to sever the flattened rib formations completely during perforation.

With reference to Figure 2 of the drawings, reference numeral 44 refers generally to an alternative embodiment of apparatus in accordance with this invention for use in forming an elongated web 10 as hereinbefore described, into bags 20 which are separable from the web 10.

The apparatus 44 comprises a drum 46 which is mounted on an axle 48 and is adapted to be rotatably driven during use in the direction indicated by the arrow 50.

The drum 46 has a series of composite stations 52 provided at equally spaced intervals about its periphery.

The spacing of the composite stations 52 about the periphery of the drum 46 is appropriate for the width of the bags 20 to be formed in the web 25 10. 16 T OFFICE 19 JAN 1984 197060 Each composite station 52 incorporates heating means for heating the rib formations of the web 10 in separation zones 24 at spaced intervals along the length of the web 10, flattening means for flattening the heated rib formations in the separation zones, welding means for welding the opposed walls of the web 10 together across the web and across the flattened rib formations in the separation zones, and weakening means for providing lines of weakening across the weld bands in the web 10.

The apparatus 44 further includes driving means (not shown) for each composite station 52 to drive the heating means, the flattening means, the welding means and the weakening means in sequence.

Thus, in use, as a separation zone 24 of the web 10 comes into contact with a composite station 52, the heating means of that station 52 will first be operated for an appropriate period to heat the rib formations in that separation zone. Thereafter the flattening means of that station comprising a hot flattening bar will be operated to flatten the heated rib formations in that separation zone.

Thereafter the further flattening means comprising a cold clamping bar of that station 52 will be operated to clamp the flattened rib formations.

Thereafter the welding means of that station 52 will be operated to form N.Z. PATENT OFFICE 19 JAN 1984 197060 a weld in a weld band extending across the web 10 in that separation Thereafter a cold clamping member of that station 52 will be operated to And finally, the weakening means of that composite station 52 will be operated to form a perforation line along the weld band.

It will be appreciated that the rate of rotation of the drum 46 and the operation of the composite stations 52 will be controlled so that all the above stpes are carried out on the web 10 while it passes over the drum 46 in contact with each particular composite station 52.

The apparatus 44 further includes an endless compression belt 54 which compresses the web 10 against the periphery of the drum 46 thereby combatting slippage between the web 10 and the drum 46.

The endless belt 54 further serves as a pressure plate for the web 10 to 20 keep the web 10 in firm engagement with the drum 46 while the various steps are carried out by the composite stations 52.

The embodiments of the invention as illustrated in the drawings provide the advantage that they provide effective methods of forming an 25 elongated web of bags which are separable from the web. zone. clamp the weld band - 18 *9 JAN $84 197060 They provide the further advantage that by flattening the rib formations in the separation zones to a thickness approaching that of the remainder of the web, the welds which are formed in the weld bands can extend ' substantially evenly across the web and across the flattened portions of the rib formations. Thus an effective sealing engagement can be obtained not only between the opposed walls but also between the flattened portions of the opposed rib formations.

They provide the further advantage that because of the flattening of the rib formations, the tendencey to leave jagged edges in these zones upon separation of bags from the web will be reduced if not entirely eliminated. /

Claims

197060 WHAT HE CLAIM IS:

1. A method of forming an elongated web of bags which are separable from the web, which includes the steps of providing an elongated double walled web of synthetic plastics material film each of the two walls of the web including a respective rib formation, which rib formations extend along the walls adjacent one elongated edge of the web, and which rib formations are adapted to interengage thereby releasably to secure said two walls to one another, heating the web in the region of the rib formations in separation zones at spaced intervals along the length of the web, flattening the rib formations in the separation zones, welding the walls of the web together in weld bands which extend across the web in register with the separation zones-to divide the web into bags, and forming lines of weakening in the weld bands to allow bags to be separated from the web along the lines of weakening.

2. A method according to claim 1, in which the web in the region of the rib formations is heated by means of hot air jets.

3. A method according to claim 1, in which the web in the region of the rib formations is heated by means of ultra sonic energy waves.

4. A method according to claim 3, in which the step of flattening the rib formations is carried out simultaneously with the step of heating the web in the region of the rib formations by applying a flattening 20 197060 anvil to the rib formations.

5. A method according to any one of claims 1 to 3, in which the rib formations are flattened by applying heated flattening bars to the rib formations.

6. A method according to claim 5, in which cold flattening bars are applied to the rib formations after application of the heated flattening bars.

7. A method according to any one of the preceding claims, in which the steps of welding the walls together in the weld bands and forming the lines of weakening are carried out simultaneously. 15

8. A method according to any one of the preceding claims, in which the lines of weakening are provided by lines of perforations in the web.

9. A method according to any one of the preceding claims, in which the web is advanced stepwise, and the steps of the method are carried out 20 cyclically at stations which are spaced along the path of movement of the web.

10. A method according to any one of the preceding claims, which includes the step of applying printing to the web in zones in register 25 with the bags. ~ M i ~ I I 19JAN1984 19706-0

11. A method of forming an elongated web of bags, substantially as described herein with reference to the accompanying drawings. 5

12. Apparatus for use in forming an elongated web of bags which are separable from the web, from an elongated double walled web of synthetic plastics rraterial film each of the two walls of the web including a respective rib formation, which rib formations extend along the walls adjacent one elongated edge of the web and which rib formations are 10 adapted to interengage thereby releasably to secure said two walls to one another and comprising heating means for heating the web in the region of the rib formations in separation zones at spaced intervals along the length of the web, flattening means for flattening the rib formations in the separation zones, welding means for welding the walls 15 of the web together in weld bands which extend across the web in register with the separation zones to divide the web into bags, and weakening means for forming lines of weakening in the weld bands to allow bags to be separated from the web along the lines of weakening. 20

13. Apparatus according to claim 12, in which the heating means comprises heated nozzles which serve to direct hot air jets onto the web in the region of the rib formations or nozzles and to a source of hot air, said source being connected to said nozzles which serve to direct hot air jets onto the web in the region of the rib formations. 25 N.Z. PATENT OFF H;t - 22 - 197 060

14. Apparatus according to claim 12, in which the heating means comprises ultra sonic energy generation means for directing ultra sonic waves onto the web in the region of the rib formations.

15. Apparatus according to claim 14, in which the flattening means comprises a pair of displaceable flattening anvils wich are associated with the heating means and are displaceable to flatten the rib formations at the same time as they are heated.

16. Apparatus according to any one of claims 12 to 14, in which the flattening means comprises a pair of hot flattening bars which are adapted to be heated and are adapted to be displaced towards each other onto the rib formations to flatten them.

17. Apparatus according to claim 16, in which the flattening means includes a pair of cold displaceable clamping bars which are displaceable towards each other to clamp the flattened portions of the rib formations. "V

18. Apparatus according to any one of claims 12 to 17, in which the welding means comprises a pair of weld bars which are adapted to be heated and are adapted to be displaced towards each other with the web between them.

19. Apparatus according to any one of claims 12 to 18, in which the - 23 - N.Z. PATENT OFFICE 19 JAN 1984 RECEIVED 197060 weakening means comprises a perforation bar having perforating teeth at spaced intervals along its length, which is adapted to be displaced onto the web to pinch the web between it and a support member of yieldable material, to perforate the web.

20. Apparatus according to any one of claims 12 to 19, including advancing means for advancing the web through the apparatus, control means for cyclically controlling operation of the heating means, and driving means for cyclically driving the flattening means, the welding means and the weakening means.

21. Apparatus according to claim 20, in which the advancing means is adapted to advance the web stepwise, in which the control means controls the heating means so that it is operative when the web is stationary, and the driving means drives the flattening means, the welding means and the weakening means so that they are operative while the web is stationary.

22. Apparatus according to claim 12, including a rotatable drum over which the web can pass, the drum having a series of composite stations at spaced intervals about its periphery, with each composite station incorporating flattening means, welding means and weakening means, including operation means associated with each composite station to operate the flattening means, welding means and weakening means of each station in sequence while a separation zone of the web passes over the - 24 - 19 JAN 1984 197060 drum in contact with the station, and including compression means to compress the web against the periphery of the drum as it passes over the drum. 5

23. Apparatus according to claim 22, in which each composite station further includes heating means adapted to be operated by the operation means in an appropriate sequence.

24. Apparatus according to claim 22 or claim 23, in which the 10 compression means comprises an endless compression belt.

25. Apparatus according to any one of claims 12 to 24, including printing means for providing printing on the web in zones in register with the bags of the web. 15

26. Apparatus according to any one of claims 12 to 25, including folding means at the leading end of the apparatus to fold a flat web along its length to form the double walled web, and including engaging means to engage the complementary engagement rib formations prior to heating of 20 the rib formations. f

27. Apparatus for use in forming an elongated web of bags which are separable from the web, substantially as described herein with reference to the accompanying drawings. 25 N.Z. PATENT OFFICE " 25 " 19 JAN 1984 '97060

28. An elongated web of bags which are separable from the web, whenever formed by the method and/or by means of the apparatus as claimed in any one of the preceding claims.

29. A bag whenever separated from an elongated web as claimed in claim 28. STRIPFORM PACKAGING (PROPRIETARY) LIMITED by its authorized agents, 3. D. BARDIE & COMPANY pec: - 26 - N.Z. PA