METHOD OF JOINING SYNTHETIC-RESIN TUBES

• US 3,847,694 A
• Filed: 02/13/1973
• Issued: 11/12/1974
• Est. Priority Date: 02/15/1972
• Status: Expired due to Term

• Current Assignee: Albert Stewing
• Original Assignee: Albert Stewing
• Inventors: Stewing, Albert
• Primary Examiner(s): Van Horn, Charles E.
• Assistant Examiner(s): Frisenda, Jr., F.
• Application Number:
  US05/332,227
• Time in Patent Office: 637 Days
• Field of Search: 156/84,85,86,305,578,294,187,213,295,303.1,320,321,293,305,311,165 285/21,381,294,297 138/155
• US Class Current: 156/86
• CPC Class Codes: B29C 61/00 Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor for surface shaping B29C59/18; for lining articles B29C63/38; for joining preformed parts B29C65/66 ; for packaging B65B53/00; connecting arrangements or other fittings for plastics pipes using shrink-down material F16L47/22, electrical connections insulated using heat shrinking insulating sleeves H01R4/72; cable junctions protected by sleeves H02G15/18
• CPC Class Codes: B29C 65/42 between pre-assembled parts B29C65/605 takes precedence
• CPC Class Codes: B29C 65/425 characterised by the composition of the molten plastics applied between pre-assembled parts
• CPC Class Codes: B29C 65/4815 Hot melt adhesives, e.g. thermoplastic adhesives
• CPC Class Codes: B29C 65/542 by injection
• CPC Class Codes: B29C 65/66 by liberation of internal stresses, e.g. shrinking of one of the parts to be joined
• CPC Class Codes: B29C 65/68 using auxiliary shrinkable elements
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/5221 for forming coaxial connections, i.e. the tubular articles to be joined forming a zero angle relative to each other
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/73715 heat-shrinkable
• CPC Class Codes: B29K 2027/06 PVC, i.e. polyvinylchloride
• CPC Class Codes: F16L 47/02 Welded joints; Adhesive joints
• CPC Class Codes: F16L 47/06 with sleeve or socket formed by or in the pipe end
• CPC Class Codes: F16L 47/22 using shrink-down material
• CPC Class Codes: Y10T 156/103 Encasing or enveloping the configured lamina
• CPC Class Codes: Y10T 24/3427 Clasp

Abstract

The spigot end of a tube made of hard polyvinyl-chloride (PVC) is fit into the heat-shrinkable bell end of a similar tube. A hot thermally-activatable adhesive is injected into the space between the bell and spigot so that it heats and shrinks the bell, causing it to compress and distribute the adhesive mass throughout the joint. The bell is formed with a circumferential bulge forming an inwardly opening circumferential recess into which the adhesive mass is injected through at least one radially opening hole. The mass of adhesive in this groove serves as a hot reservoir of glue during shrinking and distribution.

Claims

1. IN A METHOD OF FORMING A JOINT BETWEEEN TUBE AND A SLEEVE OF THERMOPLASTIC SYNTHETIC RESIN, ESPECIALLY HARD POLYVINYL CHLORIDE, IN WHICH THE SLEEVE IS HEAT-SHRUNK ONTO A PORTION OF THE TUBE SURROUNDED BY THE SLEEVE AFTER THE TUBE GAS BEEN INSERTED INTO THE SLEEVE WITH CLEARANCE THEREBETWEEN, THE IMPROVEMENT WHEREIN:

AT LEAST SAID SLEEVE IS FORMED WITH A CIRCUMFERENTIAL INWARDLY OPEN CORRUGATION DEFINING AN ANNULAR CHAMBER AROUND THE TUBE AT SAID PORTION;

THE HEAT REQUIRED FOR SHARINKING SAID SLEEVE ONTO SAID TUBE IS SUPPLIED BY INJECTING A HEATED FLOWABLE MOLTEN ADHESIVE INTO SAID CHAMBER UNDER PRESSURE, AND SAID ADHESIVE A COMPRESSED AGAINST SAID TUBE BY SAID SLEEVE UPON THE SHRINKAGE THEREOF.

2. The improvement defined in claim 1 wherein said adhesive is a mixture of a polyamide in a proportion by weight of 95 to 70 percent with an aromatic binder with active hydroxyl groups in a proportion by weight of 5 to 30 percent.