GB2038444A

GB2038444A - Improvements in tube manufacture

Info

Publication number: GB2038444A
Application number: GB7941710A
Authority: GB
Original assignee: FLINN E
Current assignee: FLINN E
Priority date: 1978-12-04
Filing date: 1979-12-03
Publication date: 1980-07-23

Abstract

A tube having an inner surface of one material such as a synthetic plastics material and an outer surface of another material such as aluminium is made by extruding a tube 1 of the plastics material and wrapping the aluminium in strip form 2, helically circumferentially or longitudinally around the extruded tube. The two materials may be bonded together by cured adhesive. Alternatively, strip form material may first be formed as a composite having two or more superposed layers and the composite helically, circumferentially or longitudinally wound around, for example, a mandrel to form the tube. <IMAGE>

Description

SPECIFICATION Improvements in tube manufacture The present invention relates to a method of manufacturing a tube and to a tube produced by such a method.

In many applications a composite tube consisting of two or more co-axial layers of different materials is required. An example of such a tube might consist of an inner layer of plastic such as polythene surrounded by an outer layer of metal such as aluminium. Any other combination of two or more materials is also possible.

This application discloses methods for the continuous production of such composite tubes.

The methods disclosed however are not restricted to the continuous manufacture of such tubes and may readily be adapted to the production of tubes of any desired length.

According to one aspect of the present invention there is provided a method of making a tube comprising the steps of producing a first layer in the form of a tube and then wrapping or folding around that tube a strip to form a second layer.

According to another aspect of the present invention there is provided a method of making a tube comprising the steps of producing a laminated material having two or more layers and then wrapping or folding that material to form the tube.

In order that the invention may be more clearly understood two embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which, Fig. 1 shows one form of the tube manufacture in which a two layer tube is produced by helically wrapping a second strip form layer over a first tubular extruded layer, Fig. 2 shows another form of the tube manufacture in which a two layer tube is produced by folding a second layer around a first tubular extruded layer so as to form a longitudinally extending seam in the second layer, and, Fig. 3 is another view of the arrangement of Fig.

2.

In the method of the first aspect of the invention (illustrated in Fig. 1) the innermost layer 1 is manufactured in the form of a continuous tube, either by extrusion or by any other suitable process. The outer layer or layers 2, in the form of sheet or foil, are then wrapped or folded around this inner tube, either separately or in combination.

Where an intimate bond between the layers is required, the layers may be bonded together by the application of heat or radiation, or any suitable adhesive material may be incorporated between the layers. This adhesive may for example consist of a material or materials which are fused or cured chemically or by heat or radiation, and may be applied to either or both of the materials to be bonded at any time prior to their being brought into contact. Where the application of heat is necessary for bonding, this may for instance be achieved by means of flame, heated air or other gas, radiant heating, induction or dielectric heating, or by direct contact with a heated surface.

The outer layer or layers may be applied either by a circumferential or helical wrapping process (as shown in Fig. 1) or by a linear wrapping or folding process (as shown in Figs. 2 and 3).

Where the circumferential or helical wrapping process is used, the outer layer 2 is applied in the form of a continuous strip or strips by a wrapping head or heads 3 which rotate around the tube.

Alternatively the tube may be rotated past a stationary wrapping head or heads, or both the tube and the wrapping head or heads may rotate.

Whether the tube or the wrapping head or heads rotate, or both, relative linear movement may be provided by moving the tube 1 longitudinally past the head or heads 3, or by moving the head or heads 3 along the tube 1 , or by moving both the tube 1 and the head or heads 3 parallel to the axis of the tube 1.

Where a linear wrapping or folding process is used, (as shown in Figs. 2 and 3) the outer foil or sheet 22 is applied to the tube 21 in the form of a continuous strip or strips parallel to the axis of the tube 21. The sheet or foil is continuously folded around the tube, giving a continuous longitudinal seam or seams 24. Again, the tube may be moved past a stationary wrapping or folding head or heads, or the wrapping or folding head or heads may move along the tube, or both the tube and the wrapping or folding head or heads may move parallel to the axis of the tube.

Whether a circumferential, helical or linear wrapping or folding process is used, at the seam or seams the edges of the foil may be butted, overlapped, folded, locked together or otherwise secured, and if necessary may be welded, secured by a suitable adhesive, or otherwise bonded.

Whether a circumferential, helical or linear wrapping or folding process is used, the tubing may if necessary be stiffened during the wrapping or folding process by cooling or by gas or air pressure or by an internal roller or rollers or by a mandrel. Such a mandrel may be fixed or movable or completely free within the tube.

The outer layer or layers applied to the tube may be printed, painted, labelled, or otherwise finished or decorated either before or after being applied to the inner tube or tubes, so that the surface of the tube may carry advertising matter, instructions, or any other legend, pattern or finish.

In the second process some or all of the layers of the composite tube are assembled in the form of foil or sheet and if necessary welded or bonded together by any suitable process or adhesive before being shaped into the tubular form. A continuous strip or strips of this composite material is then rolled into a continuous tube, forming either a helical seam or seams or a continuous longitudinal seam or seams parallel to the axis of the tube. The seam or seams may be butted, overlapped, folded, locked or otherwise finished, and if necessary welded or secured by a suitable adhesive, or otherwise bonded. After being formed into the tubular shape the tubing may be treated chemically or by heat or radiation or by dielectric or induction heating to ensure continuity of the inner or outer layer or layers or both. For example, aluminium foil may be bonded to polythene sheet or film, any desired finish or pattern being applied to the material either before or after the bonding process and before or after the composite material is shaped into the tubular form. The composite sheet may then be rolled into the form of a tube, the seam or seams being finished in any of the ways described hitherto. The tube and the seam or seams may then be heated in such a manner as to fuse the polythene layer into a continuous tubular form. The same principles may be applied to other materials or combinations of materials.

Again, the material may be supported during the forming process by a fixed or movable roller or rollers, or by a fixed, movable or free mandrel.

Claims

1. A method of making a tube comprising the steps of producing a first layer in the form of a tube and then wrapping or folding around the tube a strip to form a second layer.

2. A method as claimed in Claim 1, in which the first layer is extruded.

3. A method as claimed in claims 1 or 2, in which the second layer is formed by circumferentially or helically wrapping the strip around the first layer.

4. A method as claimed in claim 1 or 2, in which the second layer is formed by folding the strip around the first layer to produce a seam running along the axis of the tube.

5. A method as claimed in any preceding claim, in which adhesive is applied to one or more of the layers.

6. A method as claimed in claim 5, in which the adhesive consists of a curable material and is cured after application.

7. A method as claimed in claim 6, in which the adhesive is cured chemically or by heat or radiation.

8. A method as claimed in claim 6, in which, where the adhesive is heat cured, the heat is applied by means of flame, heated air or other gas, radiant heating, induction or dielectric heating, or by direct contact with a heated surface.

9. A method as claimed in any preceding claim, in which during wrapping or folding of the second layer the first tubular layer is stiffened by cooling, by gas pressure or by an internal roller, rollers or mandrel.

10. A method as claimed in any preceding claim, in which the second, outer layer is finished or decorated before being wrapped around the first tubular layer.

11. A method of making a tube comprising the steps of producing a laminated material having two or more layers and then wrapping or folding that material to form the tube.

12. A method as claimed in claim 11, in which the layers of composite material are welded or bonded together before being formed into a tube.

13. A method as claimed in claim 12, in which the layers of the composite material are bonded together by adhesive.

14. A method as claimed in any of claims 1 1 to 15, in which the material is wrapped to form either a helical seam or seams or a continuous longitudinal seam or seams parallel to the axis of tube.

15. A method as claimed in claim 14, in which the seam or seams are butted, overlapped, folded, locked or otherwise finished.

16. A method as claimed in claims 14 or 15, in which the seam or seams are welded or secured by a suitable adhesive, or otherwise bonded.

17. A method as claimed in any of claims 1 1 to 16, in which the tubing may be treated chemically or by heat or radiation or by dielectric or induction heating to ensure continuity of the inner or outer layer or layers or both.

1 8. A method as claimed in any of claims 1 1 to 1 8, in which a finish or pattern is applied to the material either before or after the bonding process and before or after the composite material is shaped into the tubular form.

19. A method of making a tube substantially as hereinbefore described with reference to Fig. 1 or to Figs. 2 and 3 of the accompanying drawing.