GB2213748A

GB2213748A - Machine for producing spirally-seamed corrugated metal tubing

Info

Publication number: GB2213748A
Application number: GB8729749A
Authority: GB
Inventors: Leif Andresen
Original assignee: Spiro Machines SA
Current assignee: Spiro Machines SA
Priority date: 1987-12-21
Filing date: 1987-12-21
Publication date: 1989-08-23
Anticipated expiration: 2007-12-21
Also published as: GB2213748B; GB8729749D0

Abstract

The machine comprises rollers (13) for preparing the edges of the metal strip (12), drive rollers (11) for feeding the metal strip into a generally cylindrical forming head (14) to bring the prepared edges of the strip into engagement with one another and clinching rollers for clinching the engaging edges of the strip to form a spiral lock-seam. Shaping rollers (17, 18, 19) are arranged around the head and adapted to engage the outer face of the strip when one of its edges has been clinched, and form at least one inwardly projecting spiral corrugation (21) which extends intermediate the turns of the spiral seam. A first shaping roller (18) engages the strip at an area substancially diametrally opposite said clinching rollers, a second shaping roller (17) engages the strip before the first shaping roller at an area angularly spaced between the clinching rollers and the first shaping roller, and a third shaping roller (19) engages the strip after the first shaping roller at an area angularly spaced between the clinching rollers and the first roller, said second and third rollers (17, 19) being angularly positioned in opposition to one another. Suitably, the shaping rollers are angular spaced apart from each other by approximately 90 DEG . <IMAGE>

Description

PRODUCTION OF SPIRALLY-SEAMED CORRUGATED METAL TUBING The invention relates to the formation of spirallyseamed metal tubing.

It is well-known to produce tubing from metal strip by feeding the strip into a forming head where the edges of the tube are joined together to form a spiral seam.

Suitably, the seam may be formed by clinching shaped edges of the strip, as in the SPIROMATIC lock-seam machines Such corrugations may be formed by means of profiled drive rollers prior to entry of the strip into the forming head, but this method has the disadvantage that at least the co-operating drive rollers must be changed each time there is a change in the required shape or number of corrugations. It may also be inconvenient to drive alreadycorrugated strips of possibly varying width through the forming head. Alternatively, the corrugations may be formed ir the head, but this involves the provision of internal and external rollers or other shaping tools, and it is difficult to mount the internal tool within the head where space is severely limited; with small-diameter tubing the space is completely inadequate.

It is an object of the present invention to provide a method and a machine for producing spirally-seamed tubing from metal strip, in which the above disadvantages are at least reduced.

According to the invention, a machine for producing spirally-seamed tubing from metal strip comprises: means for preparing the edges of the metal strip; drive rollers for feeding the metal strip into a generally cylindrical forming head to bring the prepared edges of the strip into engagement with one another; #nd, clinching rollers for clinching the engaging edges of the strip to form a spiral lock-seam;; characterised by shaping tools arranged round the head and adapted to engage the outer face of the strip when one of its edges has been clinched and form at least one inwardly-projecting spiral corrugation which extends intermediate the turns of the spiral seam, said shaping tools comprising at least one first tool engaging the strip at an area substantially diametrally opposite said clinching rollers, at least one second tool engaging the strip before the first tool(s) at an area angularly spaced between the clinching rollers and the first tool(s), and at least one third tool engaging the strip after the first tool(s) at an area angularly spaced between the clinching rollers and the first tool(s), said second and third tools being angularly positioned in opposition to one another.

Preferably, said forming tools comprise a first roller opposite the clinching rollers, and second and third rollers each angularly spaced by approximately 900 from said first rollers.

The invention further provides a process for producing spiral tubing from metal strip, comprising: preparing the edges of the metal strip: feeding the metal strip into a generally cylindrical forming head to bring the prepared edges of the strip into engagement with one another; and, clinching the engaging edges of the strip by means of clinching rollers to form the spiral lock-seam; characterised by forming at least one inwardly-projecting spiral corrugation which extends intermediate the turns of the spiral seam by means of first, second and third shaping tool means which are arranged around the head to engage the outer face of the strip when one of its edges has been clinched, the first tool means engaging the strip at an area substantially diametrally opposite said clinching rollers, the second tool means engaging the strip before the first tool means at an area angularly spaced between the clinching rollers and the first tool means, and the third tool means engaging the strip after the first tool means at an area angularly spaced between the clinching rollers and the first tool means, said second and third tool means being angularly positioned in opposition to one another.

Preferably, each of the shaping tool means comprises a roller mounted on the forming head, the rollers being angularly spaced approximately 900 apart.

In an alternative machine and a process according to the invention, the engaging edges of the metal strip are secured together by welding, preferably under the action of electrode rollers.

The inventive process has been performed very successfully in producing single corrugations in tubing formed from relatively soft metals such as aluminium, copper and deep-drawn steel. The invention has been aimed primarily at corrugating tubes of smaller diameter where the provision of the internal shaping tools is particularly difficult, but it is envisaged that the process will also be effective with larger diameter tubes formed from less flexible metals.

In the envisaged modification where the edges of the metal strip are welded together, the first forming tool would be located approximately opposite, i.e. directly aboverthe welding position.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic side elevation showing a machine for forming corrugated tubing from metal strip; Figure 2 is an end view of the machine shown in Fig. 1; and, Figures 3 and 4 are detail views showing corrugating rollers mounted on the forming head of the machine.

Referring to Fig. 1 of the drawings, the machine comprises a drive unit 10 having drive rollers 11 which draw metal strip 12 from a decoiler (not shown) and through preforming rollers 13, and feed the strip into a forming head 14 where the strip is formed into a spirally-seamed metal tube 15. The preforming rollers 13 produce, at opposite edges of the metal strip, a marginal flange and a marginal channel which are brought together in the forming head where the mating flange and channel are pressed together by clinching rollers to form a spiral lock-seam. The clinching rollers are not shown, but the lower clinching roller is mounted at the top end of piston rod 16 and the upper roller is mounted within the head on an extension of pivotal arm 16A (Fig. 2).

The tube-forming operation is similar to that of the SPIROMATIC machine as described in, for example, British Patent No. 959889, but the forming head 14 is extended and modified.

According the present invention, and as best shown in Figs. 2, 3 and 4 of the drawings, the forming head 14 is of generally helical shape but with a solid base 14A, and three rollers 17,18,19 are mounted on the head to produce an internal corrugation 21 in the tubing being formed. Each of the rollers is carried in a casing 22 which is securely bolted to the head 14 and, in the present embodiment, the rollers are spring loaded under the adjustable control of external nuts or milled heads 23.

Roller 18 is positioned directly above the clinching rollers. Rollers 17 and 19 are positioned angularly mid-way between the roller 18 and the clinching rollers, roller 17 being axially inwardly of the clinching rollers and roller 19 being axially outwardly of the clinching rollers. Thus, the rollers engage the rotating strip in the order 17-18-19, and the penetration by the rollers may increase in that order.

It has been found that, due to positioning the roller 18 directly opposite the clinching rollers, and the rollers 17 and 19 angularly opposite one another, it has been possible to form internal corrugations very satisfactorily and without the inconvenience of internal rollers or other cooperating tools.

In one specific example, a strip of aluminium alloy 1.5mm thick was formed into an 80mm diameter tube having an internal corrugation positioned mid-way between the turns of the lock-seam spiral.

The rollers 17 to 19 are described as adjustably spring-loaded, but it is anticipated that these will be replaced by hydraulically or pneumatically powered versions.

More than one corrugation may be formed by employing suitably-modified or additional rollers. It is envisaged that forming tools other than rollers may be employed, although rollers are usually preferred because of their relatively low frictional resistance.

The tubing according to the invention can be used in, for example, catalytic coverters, heat-exchange apparatus and in some ornamental articles, and also as screw couplers for similar tubing. When provided with internal and/or external sleeves, spiral passageways are formed and these passageways can be functionally attractive in many applications including heat-exchange and catalytic conversion.

In an alternative machine according to the invention, the tubing is formed by welding, for example as described in our copending British Patent Application No. 8728411.

In this case the roller 18 is located directly above the electrode rollers and the rollers 17 and 19 are again located angularly midway between the electrode rollers of the roller 18.

Claims

1. A machine for producing spirally-seamed tubing from metal strip, comprising: means for preparing the edges of the metal strip; drive rollers for feeding the metal strip into a generally cylindrical forming head to bring the prepared edges of the strip into engagement with one another; and, clinching rollers for clinching the engaging edges of the strip to form a spiral lock-seam; characterised by shaping tools arranged around the head and adapted to engage the outer face of the strip when one of its edges has been clinched and form at least one inwardly-projecting spiral corrugation which extends intermediate the turns of the spiral seam, said shaping tools comprising at least one first tool engaging the strip at an area substantially diametrally opposite said clinching rollers, at least one second tool engaging the strip before the first tool(s) at an area angularly spaced between the clinching rollers and the first tool(s), and at least one ,third tool engaging the strip after the first tool(s) at an area angularly spaced between the clinching rollers and the first tool(s), said second and third tools being angularly positioned in opposition to one another.

2. A machine according to Claim 1, wherein said forming tools comprise a first roller opposite the clinching rollers, and second and third rollers each angularly spaced by approximately 900 from said first roller.

3. A process for producing spiral tubing from metal strip, comprising: preparing the edges of the metal strip; feeding the metal strip into a generally cylindrical forming head to bring the prepared edges of the strip into engagement with one another; and, clinching the engaging edges of the strip by means of clinching rollers to form the spiral lock-seam; characterised by forming at least one inwardly-projecting spiral corrugation which extends intermediate the turns of the spiral seam by means of first, second and third shaping tool means which are arranged around the head to engage the outer face of the strip when one of its edges has been clinched, the first tool means engaging the strip at an area substantially diametrally opposite said clinching rollers, the second tool means engaging the strip before the first tool means at an area angularly spaced between the clinching rollers and the first tool means, and the third tool means engaging the strip after the first tool means at an area angularly spaced between the clinching rollers and the first tool means, said second and third tool means being angularly positioned in opposition to one another.

4. A process according to Claim 3, wherein each of the shaping tool means comprises a roller mounted on the forming head, the rollers being angularly spaced approximately 900 apart.

5. A process for producing spiral tubing from metal strip comprising: feeding the metal strip into a generally cylindrical forming head to bring the edges of the strip into engagement with one another; and, securing together the edges of the strip by means of welding at the position where the edges engage; characterised by forming at least one inwardly-projecting spiral corrugation which extends intermediate the turns of the spiral seam by means of first, second and third shaping tool means which are arranged around the head to engage the outer face of the strip when one of its edges has been welded, the first tool means engaging the strip at an area substantially diametrally opposite the welding position, the second tool means engaging the strip before the first tool means at an area angularly spaced between the welding position and the first tool means, and the third tool means engaging the strip after the first tool means at an area angularly spaced between the welding position and the first tool means, said second and third tool means being angularly positioned in opposition to one another.

6. A process according to Claim 5, wherein said prepared edges overlap one another and said welding is effected by electrode rollers to produce stitch welding.

7. A process according to Claim 6, wherein said forming tools comprise a first roller opposite to the welding rollers and second and third rollers each angularly spaced by approximately 900 from said first roller.

8. i A machine for producing spirally-seamed tubing from metal strip, substantially as hereinbefore described with reference to the accompanying drawings.

9. A process for producing spirally-seamed tubing from metal strip, substantially as hereinbefore described with reference to the accompanying drawings.

10. Spirally-seamed metal tubing whenever produced in an apparatus or by a process as claimed in any preceding Claim.