GB1597802A

GB1597802A - Method and apparatus for fixing a stabilizing member on a container

Info

Publication number: GB1597802A
Application number: GB17003/78A
Authority: GB
Original assignee: PLM AB
Current assignee: Rexam AB
Priority date: 1977-05-02
Filing date: 1978-04-28
Publication date: 1981-09-09
Also published as: ES469839A1; DE2817059A1; BR7802648A; AT380828B; DK190678A; IT7867984A0; SE406291B; FR2389474B1; FR2389474A1; JPS6139896B2; DE2817059C2; AU3556378A; CA1124477A; CH628586A5; IT1107198B; JPS53136075A; SE7705037L; BE866600A; ZA781911B; ATA318278A

Abstract

The device for welding a plastic base part (30) to a plastic container (10), for example a bottle, has a holder (20) for receiving in each case a base part (30) which is dispensed from a magazine (60). The container (10) with its base is, by means of a holding-down device (40), subject to the effect of pressure, placed on a base part (30) in the holder (20). A welding mandrel (51), for example for ultrasonic welding, is moved from a lower position into an upper position in which it is disposed in the holder (20) and effects a welding of the base of the container (10) to the base part (30). Such a container can be, for example, a plastic bottle suitable for carbonated beverages which ensures reliable standing on a flat support. <IMAGE>

Description

(54) METHOD AND APPARATUS FOR FIXING A STABILIZING MEMBER ON A CONTAINER (71) We, PLM AB, a Swedish Company of Fack, SW-201 10 Malt6, Sweden, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a method and apparatus for fixing a stabilizing member, for example a foot, onto a container, for example a bottle. The invention is suitable for application where the stabilizing member and also the container consist of plastics material.

There is great interest in the ability to make containers of plastics material for storing beverages, for example. This interest is due, among other factors, to the desire to reduce the weight of the packaging material used, as far as this is possible, and at the same time to utilize the good properties of plastics material, for example in respect of impact strength. The types of plastics material used for this purpose are however relatively expensive, so that in connection with the consumption of material it is obviously also necessary for reasons of economy to employ the smallest possible wall thickness of the containers used. In order to withstand the loads to which the material packed in the containers is exposed, the parts of the containers which are subjected to these stresses, for example the bottom of a bottle, must be so constructed as to make the most effective possible use of the strength of the material. This is particularly important when containers of plastics material are used to store materials under pressure, for example beverages containing carbon dioxide. Because of the requirements explained above, this means that the bottom of a container should have a mainly circular shape.

For a container, for example a bottle, for storing materials it is an essential requirement that it should be possible for the container to be stored in an upright position. With a container having a bottom of circular shape this is obviously simply impossible. This has in turn the consequence that containers of the kind described here are equipped with stabilizing members, for example, feet. Various types of feet have been used, being either parts projecting from the bottom of the bottle or separate parts fixed to the containers. In the last-mentioned case these parts are applied to the container, for example, by snap engagement, riveting, or comparable methods.

According to the present invention there is provided a method of fixing a stabilizing member of plastics material on to a container of plastics material, comprising applying a force to a central portion of the bottom of the stabilizing member to displace that central portion relative to the other parts of the stabilizing member so as to produce a bending moment in the stabilizing member and cause the central portion thereof to lie against a central portion of the bottom of the container, and applying energy to said central portions, whereby the stabilizing member is fixed to the container in the central portions of the bottoms of the member and container respectively with the central portion of the stabilizing member remaining substantially in the position to which it is displaced relative to the other parts of the member.

The invention may be applied to combinations of plastics material in the stabilizing member and container when the plastics material in the stabilizing member and container are weldable. Examples of such plastics materials are polyethylene, polyethylene terephthalate, poly acrylonitrile, and polyvinyl chloride.

The bending moment is produced in the stabilizing member by displacing the central portion of the bottom of the stabilizing member relative to the other parts of the latter before the fixing is carried out. This displacement is achieved by moving the central portion in the direction of the bottom of the container so that after application to the container a stabilizing member disposed in this form presses by its upper edge against the container.

In an embodiment of the invention the inclination of the bottom of the container which has a tendency to become deformed during the fixing of the stabilizing member is compensated by subjecting the internal volume of the container to pressure. This embodiment is often suitable for use with thin-walled containers. As an alternative, the application of pressure is replaced by mechanical holding means.

The invention also provides apparatus for carrying out the method defined above, the apparatus comprising a supporting element for receiving and carrying a stabilizing member, a gripping element arranged to grip the mouth of the container and to urge the bottom of the container towards the stabilizing member, the supporting element including means for applying a force to a central portion of the bottom of the stabilizing member to displace said central portion such that said central portion is caused to lie against a central portion of the bottom of the container, an element for applying energy arranged to be brought by drive means into contact with the central portion of the stabilizing member and to heat the material of the central portions of the bottoms of the member and container respectively to fix the stabilizing member to the container.

The element for applying energy may be, for example, an element for ultrasonic welding.

If necessary, the container is given a stable shape during the course of the fixing operation by holding means which are positioned against the inner surface of the central portion of the bottom of the container, or by increasing the pressure within the container.

Two concentrically disposed rings may be provided in the supporting element for the stabilizing member. The outer ring is adapted to the outside dimensions of the stabilizing member and is preferably disposed on a number of relatively soft springs. The inner ring has an inside diameter which is adapted to the outside diameter of a mandrel for applying energy. In this arrangement it is made possible for the mandrel to slide through the inner ring for the purpose of bearing against a stabilizing member when the latter rests against the inner ring.

When a stabilizing member has been introduced into the supporting element, it rests with the central portion of its bottom against the upper surface of the inner ring and is at the same time centred in the supporting element by the outer ring. In the embodiment where the outer ring is suspended on springs, it is situated in an upper position in dependence on the action of the springs.

A gripping means acts in sequence on the containers in such a manner that they are brought into a position with their bottom parts disposed in the stabilizing member. The latter more or less embraces the bottom part of the container. The gripping means then urges the container in the direction of the stabilizing member. The central portion of the bottom of the stabilizing member is fixed in position in the supporting element with respect to the inner ring, whereas the outer parts of the stabilizing member are displaced relative to the central portion of the bottom through the action of the container. If necessary, this is permitted by the previously mentioned spring suspension of the outer ring.

Through this displacement of the container, reliable contact is also obtained between the central portion of the bottom of the container and the central portion of the stabilizing member.

In one embodiment of the invention an arrangement simultaneously embraces the mouth portion of the container in such a manner that the latter forms a closed space.

Pressure is applied to the interior of the container, whereby it is stabilized against mechanical displacement. The element used for embracing the mouth portion of the container preferably consists of the previously mentioned gripping element.

The previously mentioned assistance in the displacement of the container for a relative movement of the material of the stabilizing member is preferably provided by the gripping element. In one embodiment the gripping element is displaced with a roller lying against a cam so that when a relative displacement occurs between the roller and the cam the gripping element is displaced in the direction of the stabilizing member.

With the stabilizing member and the container fixed in relation to one another in the manner described above, a mandrel is thereupon guided through the inner ring so as to come into contact with the material in the central portion of the bottom of the stabilizing member for the purpose of applying energy thereto, for example, ultrasonic energy.

Ultrasonic energy is given up to the material of the stabilizing member and container, and the stabilizing member is thus welded in this region to the bottom of the container. With the stabilizing member and the container also fixed in relation to one another by external elements, the welded part is then cooled, the internal excess pressure (where applied) is relaxed or the holding means used is removed, whereupon the external fastening element is taken away and the container together with the stabilizing member welded to it is carried away from the production unit.

The inner ring is preferably mounted for sliding in the supporting element, so that the distance of the container in the axial direction between the upper surface of the inner ring and the upper surface of the outer ring is adjustable.

The relative displacement between the cen tral portion of the bottom of the stabilizing member and the remainder of the latter is effected in an alternative embodiment of the invention through the displacement of the inner ring, optionally in conjunction with the displacement of the outer ring The positioning of the individual stabilizing member in the supporting element and also the displacement of the containers with or without the stabilizing member can be effected in accordance with a known technique. Thus, for example, a suction means may be used to secure the stabilizing member and a suction discharge pipe for bringing the completed containers to a storage site.

An embodiment of the invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: FIGURE 1 shows a perspective view of apparatus for fixing stabilizing members to containers in accordance with the invention, and FIGURE 2 shows a detail of the apparatus of Figure 1 illustrating how an element for fixing a stabilizing member to a container is mounted.

In Figure 1 a plate 100 is mounted on a shaft driven by a mechanism 101. The plate is rotatable stepwise so as to assume fixed stopping positions. A number of supporting elements 20 are disposed on the plate 100.

The supporting elements are adapted to the dimensions of stabilizing members 30 which are to be fixed to containers 10. A control element 21 adapted to the dimensions of the containers is fixed to each supporting element 20. An element 50 for applying energy, for example an ultrasonic welding element, is aligned with one of the positions of the supporting elements 20. The element 50 is equipped with a mandrel 51 which can be displaced from a lower position lying under the plate 100 to an upper position in which the mandrel extends within the supporting element 20. A cooling element 52 is aligned with a position of the supporting elements 20 downstream of said element 50. The cooling element is also provided with a mandrel 53 which can be moved between a lower position below the plate 100 and an upper position in which the mandrel extends within the supporting element 20.

A gripping element 40 is provided for each individual supporting element 20 and is arranged to assume a position in which it secures an individual container 10 on the respective supporting element 20. In the illustrated embodiment of the invention the gripping elements 40 are connectible to pressure application means 81, which consists for example of a container for compressed air and is equipped with valves for connecting and disconnecting each gripping element to and from the pressure application means. The gripping elements are arranged to make sealing connection with the mouth portions of the containers, so that when the valve connected to the pressure application means is opened an excess pressure is produced in the containers.

A supporting plate 80 is arranged to cooperate with the gripping element 40. In the illustrated embodiment the gripping elements 40 are each provided with a roller 41 lying against the supporting plate 80. The direction and shape of the supporting plate 80 are so selected that when it performs movement relative to the supporting plate 100 the gripping element 40 is moved in the direction of the supporting elements 20.

The stabilizing members 30 are fed to the supporting elements 20 by way of a magazine 60 for loose stabilizing members, a feed means 61, for example a worm, and a suction element 62. The suction element 62 secures a stabilizing member fed by the feed means and brings it into the desired position in the supporting element 20. The suction element 62 is movable between a position under the plate 100 and a position above the supporting element 20. The suction element is common to all the supporting elements 20. Finished containers with stabilizing members fixed to them are discharged with the aid of a suction discharge pipe 70, as shown in Figure 1.

Figure 2 shows in detail how each supporting element 20 is mounted in one embodiment of the invention. The plate 100 and a mandrel can be seen in the drawing, the mandrel being either a mandrel 51 for applying energy, for example for ultrasonic welding, or a mandrel 53 for cooling. In addition, the bottom part of the container 10 is shown, as well as the stabilizing member 30. In addition to these parts, the Figure also shows an outer ring 22, preferably of metal, and an inner ring 23. The outer ring is mounted on a number of springs 24, so that the ring can be moved between an upper position of rest some distance from the plate 100 and a lower position close to the said plate. The inner diameter of the outer ring 22 is adapted to the outside diameter of the stabilizing member 30, so that the outer ring lies against the stabilizing member.

In the drawing the inner ring 23 is joined to the plate 100. It is usually displaceable with respect to the plate 100, for example by being screwed into the plate by means of a screwthread. The inside diameter of the ring 23 enables the mandrel 51 or 53 to pass through it. It can also be seen from the drawing that the plate 100 also permits the passage of the mandrel. The upper surface of the inner ring 23 lies approximately flush with the bottom surface of the outer ring 22.

In Figure 2 it is shown how the central portion of the bottom of the container 10 is situated some distance from the central portion of the bottom of the stabilizing member 30 This is the starting position for the container when the latter has first been brought into a position for fixing to the stabilizing member. In the following stage of the process the container is acted on by forces which are directed towards the stabilizing member, so that the container together with the outer parts of the stabilizing member is displaced towards the plate 100. The central portion of the bottom of the container 10 thus reaches a position in which the material of that portion is pressed against the material in the central portion of the bottom of the stabilizing member. Since it is suspended on the springs 24, the outer ring 22 can follow the stabilizing member in the movement just mentioned. The welding and cooling of the welded region are effected with the container and stabilizing member lying in the position close to the plate 100.

The mode of operation of the apparatus described above and illustrated in Figures 1 and 2 is explained below.

In this the progress of one supporting element 20 is described as it is moved by the rotation of the plate 100, and the operations which take place at each position of this supporting element 20 are described. It will be appreciated that all of the supporting elements 20 are sequentially moved in the same manner. With the aid of the feed means 61 stabilizing members 30 are fed individually from the magazine 60 to the supporting elements 20. This takes place with the supporting element 20 receiving the stabilizing member in the position designated 1. The final positioning of the stabilizing member in the supporting element at position 1 is effected by the suction element 62, which takes over the stabilizing member 30 after the latter has been delivered by the feed means 61.

The control element 21 assists the suction element to correctly orientate the stabilizing member.

The plate 100 is thereupon moved one step in its direction of rotation so that the supporting element 20 containing the stabilizing member 30 is moved to position 2 and a container 10 is placed on the supporting element 20 at position 2 by means not shown in the drawing. Thus, the container 10 is placed on the stabilizing member 30 in the supporting element. The control element 21 ensures the correct orientation of the container.

The gripper 40 associated with the supporting element at position 2 is then brought into position to close the mouth portion of the container 10.

The plate 100 is then moved on one step to move the supporting element 20 at position 2 to position 3. In the position, if necessary, pressure is then applied to the interior of the container. The roller 41 of the gripping element 40 contacts the plate 80 at position 3 and is operated during the movement of the supporting plate 80 in such a manner that the container 10 is moved towards the supporting element 20. The stabilizing member 30 is thus acted on by the container 10 in such a manner that the stabilizing member and the container assume correct positions relative to one another for the subsequent welding.

The plate 100 is now moved on one step to move the supporting element from position 3 to position 4. The mandrel 51 on the element 50 for the supply of energy, for example for ultrasonic welding, is moved upwards towards the central portion of the bottom of the stabilizing member 30. Energy, for example ultrasonic energy, is applied by the mandrel and the material in the central portion of the bottom of the stabilizing member and in the central portion of the bottom of the container is heated and the container is thereby welded to the stabilizing member at position 4. The mandrel 51 then returns to its lower position below the plate 100.

The plate 100 is then moved on one more step to move the supporting element from position 4 to position 5. The mandrel 53 of the cooling means 52 then assumes a position in which it contacts the central portion of the bottom of the stabilizing member 30 and thus cools the material in this region and also in the region of the central portion of the bottom of the container. This cooling lasts until the necessary strength has been achieved in the bond between the stabilizing member and the container.

The plate 100 is moved on one step more, and the roller 41 on the gripping element 40 is freed from engagement with the supporting plate 80. The application of pressure to the interior of the container, in cases where pressure is applied, then ceases. The gripping element can thus return to its starting position. The container together with the stabilizing member welded to it is released for removal from the apparatus. This can be achieved for example with the aid of an ejection device or with the aid of a suction pipe 70.

With the construction described a number of positions may be provided for the supporting element 20 between the position for cooling the welding region and the position for removal from the production unit.

These positions may for example be utilised for inspecting the products and also for ejecting any which do not pass this inspection.

The apparatus described also makes it possible for a central control system for the sequence of production operation to be provided, for example with the aid of a microdator. The latter attends to all the control functions and pulses necessary for enabling the operating elements to make the movements necessary for the sequence of operations.

In some applications the outer ring 22 may have a fixed orientation in relation to the plate 100. This arrangement is expedient when the additional security provided through the movable suspension of the outer ring 22 in respect of the orientation of the bottom of the container in relation to the stabilizing member is not necessary.

The foregoing text described apparatus of the invention and consisting of a number of working stations which are positioned on a plate 100, which performs a circular movement during the course of the operation. It is obvious that the invention is not restricted to the use of an apparatus arranged in this manner, but may also be applied to an apparatus having working stations arranged substantially linearly.

An advantage of the invention which has not so far been mentioned consists in that when fastened to the container the stabilizing member is assured of accurate orientation in relation to the vertical axis of the container.

Problems in connection with the filling of the container are thus overcome. Previously known foot constructions in which a foot is clipped onto the container do not provide the accurate orientation achieved with the invention.

WHAT WE CLAIM IS:- 1. A method of fixing a stabilizing member of plastics material on to a container of plastics material, comprising applying a force to a central portion of the bottom of the stabilizing member to displace that central portion relative to the other parts of the stabilizing member so as to produce a bending moment in the stabilizing member and cause the central portion thereof to lie against a central portion of the bottom of the container, and applying energy to said central portions whereby the stabilizing member is fixed to the container in the central portions of the bottoms of the member and container respectively with the central portion of the stabilizing member remaining substantially in the position to which it is displaced relative to the other parts of the member.

2. A method as claimed in claim 1, wherein the mechanical stability of the container during the fixing operation is increased by placing the interior of the container under pressure.

3. A method as claimed in claim 1, wherein the mechanical stability of the container during the fixing operation is increased by applying a mechanical holding means against the inner surface of the central portion of the bottom of the container.

4. Apparatus for carrying out the method claimed in any of claims 1 to 3, comprising a supporting element for receiving and carrying a stabilizing member, a gripping element arranged to grip the mouth of the container and to urge the bottom of the container towards the stabilizing member, the supporting element including means for applying a force to a central portion of the bottom of the stabilizing member to displace said central portion such that said central portion is caused to lie against a central portion of the bottom of the container, an element for applying energy arranged to be brought by drive means into contact with the central portion of the stabilizing member and to heat the material of the central portions of the bottoms of the member and container respectively to fix the stabilizing member to the container.

5. Apparatus as claimed in claim 4, wherein said element for applying energy is an ultrasonic welding element.

6. Apparatus as claimed in claim 4 or 5, wherein the gripping element is arranged to cause compressive forces between the bottom of the container and the stabilizing member.

7. Apparatus as claimed in any of claims 4 to 6, further comprising an element for cooling the heated material after the fixing of the bottom of the container to the bottom of the stabilizing member.

8. Apparatus as claimed in any of claims 4 to 7, further comprising a pressure element for placing the interior of the container under pressure, whereby the container is mechanically stabilized during the fixing and cooling processes.

9. Apparatus as claimed in any of claims 4 to 8, further comprising mechanical holding means for lying against the inner surface of the container, in the region where the container is heated, during the fixing and cooling processes.

10. Apparatus as claimed in any of claims 4 to 9, wherein the supporting element is provided with an outer ring matching the outside dimensions of the stabilizing member and said means for applying a force to the central portion of the bottom of the stabilizing member comprises an inner tubular part which is arranged with one of its end portions lying against the central portion of the bottom of the stabilizing member, the tubular part being so shaped that it permits the passage of the element applying energy so as to enable it to bear against the central portion of the bottom of the stabilizing member.

11. Apparatus as claimed in claim 10, wherein the outer ring is connected by way of springs to a plate which carries the supporting element, and the tubular part is adjustably fixed in the plate such that when forces are applied to the edge of the stabilizing member in the direction of the plate the outer portions of the stabilizing member are displaced relative to the central portion of the bottom of the stabilizing member lying against the tubular part.

12. Apparatus as claimed in any of claims 4 to 11, further comprising a magazine for storage of stabilizing members, and feed means

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. In some applications the outer ring 22 may have a fixed orientation in relation to the plate 100. This arrangement is expedient when the additional security provided through the movable suspension of the outer ring 22 in respect of the orientation of the bottom of the container in relation to the stabilizing member is not necessary. The foregoing text described apparatus of the invention and consisting of a number of working stations which are positioned on a plate 100, which performs a circular movement during the course of the operation. It is obvious that the invention is not restricted to the use of an apparatus arranged in this manner, but may also be applied to an apparatus having working stations arranged substantially linearly. An advantage of the invention which has not so far been mentioned consists in that when fastened to the container the stabilizing member is assured of accurate orientation in relation to the vertical axis of the container. Problems in connection with the filling of the container are thus overcome. Previously known foot constructions in which a foot is clipped onto the container do not provide the accurate orientation achieved with the invention. WHAT WE CLAIM IS:-

1. A method of fixing a stabilizing member of plastics material on to a container of plastics material, comprising applying a force to a central portion of the bottom of the stabilizing member to displace that central portion relative to the other parts of the stabilizing member so as to produce a bending moment in the stabilizing member and cause the central portion thereof to lie against a central portion of the bottom of the container, and applying energy to said central portions whereby the stabilizing member is fixed to the container in the central portions of the bottoms of the member and container respectively with the central portion of the stabilizing member remaining substantially in the position to which it is displaced relative to the other parts of the member.

for feeding stabilizing members individually from the magazine to the supporting element.

13. Apparatus as claimed in any of claims 4 to 12, further comprising a control element for aligning the container in relation to a supporting element in order to cause the container to lie against a stabilizing member positioned in the supporting element.

14. Apparatus as claimed in any of claims 4 to 13, further comprising a suction discharge pipe for moving the container together with the stabilizing member fixed to it from the supporting element upon the completion of the fixing operation.

15. Apparatus as claimed in any of claims 4 to 14, further comprising means for moving the container between a number of positions and for holding the container stationary for a period of time in each position.

16. A method of fixing a stabilizing member of plastics material on to a container of plastics material, substantially as hereinbefore described with reference to the accompanying drawings.

17. Apparatus for carrying out the method according to claim 1, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

18. A container of plastics material having a stabilizing member of plastics material fixed thereon by the method of any one of claims 1 to 3 or 16, or by the apparatus of any one of claims 4 to 15, or 17.