# US 5,704,537 A · Method for sheathing a plastic tube with a metal sheathing

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- Number: US 5,704,537 A
- Document ID: US5704537A
- Status: Granted
- Kind: A
- Application number: 08/539,116
- Filed: 1995-10-04
- Granted: 1998-01-06
- Earliest claimed: 1995-04-29
- Assignees: Hewing GmbH
- Inventors: Emil Heinrich Friedrich
- Web page: https://patentgrep.com/patent/US5704537A

## CPC

- B21C 37/154: {Making multi-wall tubes}
- B21C 37/08: Making tubes with welded or soldered seams {(with helically arranged seams B21C37/122)}
- B21C 37/0822: {Guiding or aligning the edges of the bent sheet}
- B21C 37/083: Supply, or operations combined with supply, of strip material
- B29C 48/00: Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor (extrusion blow-moulding B29C49/04)
- B29C 48/0017: {combined with blow-moulding or thermoforming}
- B29C 48/0019: {combined with shaping by flattening, folding or bending}
- B29C 48/0021: {combined with joining, lining or laminating}
- B29C 48/0022: {combined with cutting}
- B29C 48/09: Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
- B29C 48/151: Coating hollow articles
- B29C 48/21: the layers being joined at their surfaces
- B29K 2105/0097: {Glues or adhesives, e.g. hot melts or thermofusible adhesives}
- B29K 2305/02: Aluminium
- B29K 2995/0067: non-permeable
- B29L 2009/003: {comprising a metal layer}
- B29L 2023/22: {Tubes or pipes, i.e. rigid (bent tubes not for use as pipe couplings B29L2023/004)}
- B21C: MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

In a method for sheathing a plastic tube with a metal sheathing, a metallic band (20) is laid around a plastic tube (14), the metallic band (20) comprising longitudinal edges (32) bent to a common side thereof, which are, when the metallic band (20) is laid around the plastic tube (14), in abutment and extend substantially parallel to the longitudinal axis of the plastic tube (14) and are welded together. The volume of the bent longitudinal edges (32) and the welding energy are chosen such that the metallic band (20) welded together at its longitudinal edges comprises, in the region of the longitudinal seam (46), an outer surface (50) lying substantially within the outer peripheral surface (48) of the metal sheathing after welding.

## Claims

### Claim 1

A method for sheathing a plastic tube with a metal sheathing comprising the steps of:
forming a metallic band from a metallic blank, the band having an intermediate section and two longitudinal edges, each of said edges being bent to project away from a common side of the intermediate section, including
molding L-shaped flanges on each of two longitudinal edge portions of the metallic blank, a first leg of each L-shaped flange projecting from a middle section of the metallic blank, a second leg of said each L-shaped flange extending from each said first leg in parallel to the middle section, and
separating the second legs from the first legs, so that the first legs are the edges of the band,
wrapping the metallic band (20) around a plastic tube, the metallic band (20) comprising longitudinal edges (32) bent to a common side of the metallic band to form the metal sheathing, said wrapping including abutting the edges to each other to extend substantially parallel to the longitudinal axis of the plastic tube when the metallic band is wrapped around the plastic tube, and
welding the two edges to each other to form a longitudinal weld seam, wherein
the material volume of the edges and the welding energy are selected such that the metallic band welded together at its edges comprises, in the region of the longitudinal weld seam, an outer surface located substantially within the virtual extension line of the outer peripheral surface of the metal sheathing after welding.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the first and second angles are each about 90.degree..

### Claim 3 (depends on 1)

The method according to claim 1, wherein the outer surface of the longitudinal weld seam slightly protrudes outward beyond the virtual extension line of the outer peripheral surface of the metal sheathing after welding.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the step of welding the longitudinal weld seam includes producing on an inner peripheral surface of the metallic sheathing two protrusions with a depression therebetween.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the step of separating said each second leg is effected by using a pair of trimming rolls having a cutting roll and a counter roll, the cutting roll engaging on the middle section and on one of the first legs and the counter roll engaging on the middle section, said one of the first legs, and, for a distance equal to the thickness of the metallic blank, on one of the second legs.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the outer surface of the longitudinal weld seam extends no more than 1/5 of a thickness of the metallic band outward beyond the virtual extension line of the outer peripheral surface of the metal sheathing after welding.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the said one and the other of said edges are at a first angle and a second angle to the intermediate middle section, the sum of the first and second angles being about 180.degree..

### Claim 8 (depends on 7)

The method according to claim 7, wherein the first and second angles are each about 90.degree..

### Claim 9 (depends on 1)

The method according to claim 1, wherein the forming step further includes guiding a metallic blank having two longitudinal edges into the clearance between the peripheral surfaces of first and second molding rolls of at least one pair of rolls prior to molding the L-shaped flanges, the molding rolls comprising complementary peripheral molding surfaces for engaging the metallic blank on both sides thereof.

### Claim 10 (depends on 9)

The method according to claim 9, wherein said first molding roll has a circumferential raised central part and said second molding roll has a circumferential central depression in their respective peripheral molding surfaces.