Heat fusion fitting

• US 6,998,588 B2
• Filed: 06/03/2003
• Issued: 02/14/2006
• Est. Priority Date: 05/22/1997
• Status: Expired due to Fees

• Current Assignee: Uponor Incorporated (Uponor Wirsbo Company)
• Original Assignee: Uponor Incorporated (Uponor Wirsbo Company)
• Inventors: Jarvenkyla, Jyri, Harget, David Charles
• Primary Examiner(s): Bennett, Henry
• Assistant Examiner(s): PATEL, VINOD D
• Application Number:
  US10/454,205
• Publication Number:
  US 20030209904A1
• Time in Patent Office: 987 Days
• Field of Search: 219/544, 219/535, 219/494, 264/230
• US Class Current: 219/544
• CPC Class Codes: B29C 57/04 using mechanical means B29C57/025 takes precedence
• CPC Class Codes: B29C 65/3632 comprising several wires, e.g. in the form of several independent windings B29C65/364 takes precedence
• CPC Class Codes: B29C 65/368 with a polymer coating
• CPC Class Codes: B29C 65/4815 Hot melt adhesives, e.g. thermoplastic adhesives
• CPC Class Codes: B29C 65/5057 positioned between the surfaces to be joined B29C65/5035 takes precedence
• 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 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/1222 comprising at least a lapped joint-segment
• CPC Class Codes: B29C 66/1226 comprising at least one bevelled joint-segment
• 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 66/5229 involving the use of a socket
• CPC Class Codes: B29C 66/52292 said stop being internal
• CPC Class Codes: B29C 66/5344 said single elements being substantially annular, i.e. of finite length, e.g. joining flanges to tube ends B29C66/5346 takes precedence
• 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 66/72343 for liquids
• CPC Class Codes: B29C 66/73751 the to-be-joined area of at least one of the parts to be joined being uncured, i.e. non cross-linked, non vulcanized
• CPC Class Codes: B29C 66/73776 the to-be-joined areas of both parts to be joined being crystalline
• CPC Class Codes: B29C 66/73921 characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/91411 of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/919 characterised by specific temperature, heat or thermal flux values or ranges specific electrical resistance values B29C66/81262
• CPC Class Codes: B29C 66/91921 : in explicit relation to another temperature, e.g. to the softening temperature or softening point, to the thermal degradation temperature or to the ambient temperature
• CPC Class Codes: B29C 66/91931 : in explicit relation to the fusion temperature or melting point of the material of one of the parts to be joined
• CPC Class Codes: B29C 66/91933 : higher than said fusion temperature
• CPC Class Codes: B29C 66/949 : characterised by specific time values or ranges
• CPC Class Codes: B29D 23/005 : provided with electrical wiring
• CPC Class Codes: B29K 2023/06 : PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/0691 : PEX, i.e. crosslinked polyethylene
• CPC Class Codes: B29K 2023/08 : Copolymers of ethylene B29K2023/16 takes precedence
• CPC Class Codes: B29K 2023/086 : EVOH, i.e. ethylene vinyl alcohol copolymer
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2023/14 : Copolymers of polypropylene B29K2023/16 takes precedence
• CPC Class Codes: B29K 2023/18 : Polymers of hydrocarbons having four or more carbon atoms, e.g. polymers of butylene, e.g. PB, i.e. polybutylene
• CPC Class Codes: B29K 2027/06 : PVC, i.e. polyvinylchloride
• CPC Class Codes: B29K 2067/006 : PBT, i.e. polybutylene terephthalate
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: F16L 47/03 : Welded joints with an electrical resistance incorporated in the joint
• CPC Class Codes: Y10T 428/1355 : Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• CPC Class Codes: Y10T 428/1393 : Multilayer [continuous layer]

Abstract

A method for the manufacture of a heat fusion fitting, which comprises i) forming a body (1) comprising at least a first layer of a first cross-linked polymeric material, ii) embedding or partly embedding a ferromagnetic heating element (11, 12) in a second polymeric material (13, 14) to form an insert (7, 8), the ferromagnetic heating element (11, 12) having a Curie temperature equal to or greater than the crystalline melting point or softening point of the second polymeric material (13, 14), and iii) assembling the body and the insert (7, 8) to form the fitting.

Claims

1. A heat fusion fitting comprising a body of hollow, tubular construction comprising at least a first, outer layer of a first cross-linked polymeric material, the body being expandable at a temperature below the crystalline melting point or softening point of the first polymeric material, the fitting further comprising a second, inner layer of a second polymeric material and a ferromagnetic heating element, the ferromagnetic heating element being embedded or partly embedded in the second layer and having a Curie temperature equal to or greater than the crystalline melting point or softening point of the second polymeric material, the body and the insert being assembled to form the fitting such that there is still some unresolved recovery in the body region surrounding the ferromagnetic heating element.

5. A fitting according to claim 1 or claim 4, in which the body has either corrugations or ribs on its outer surface.

6. A fitting according to claim 1, in which the body is of dual layer or multi-layer construction, and at least one of the layers is a barrier layer.

7. A fitting according to claim 1, in which the body of the fitting has been shaped by a continuous extrusion method.

8. A fitting according to claim 1, in which the first polymeric material is polyethylene or an ethylene co-polymer.

9. A fitting according to claim 1, in which the first polymeric material has been cross-linked by a chemical cross-linking method.

10. A fitting according to claim 1, in which the ferromagnetic heating element comprises a wire of conductive material covered with a ferromagnetic material.

11. A fitting according to claim 1, in which the second polymeric material is uncross-linked polyethylene.

12. A fitting according to claim 1, in which the ferromagnetic heating element is wholly embedded in the second polymeric material.

13. A fitting according to claim 1, in which the ferromagnetic heating element has a Curie temperature of from 20°

C. to 80°

C. greater than the crystalline melting point or softening point of the second polymeric material.

14. A fitting according to claim 1, in which the second layer extends axially of the ferromagnetic heating element to form “

cold zones”

which, in use, contain the flow of melt from the melt region.

15. A fitting according to claim 1, in which the second layer has end sections provided with internal grooves for accommodating sealing means.

17. A pipe joint formed using a heat fusion fitting according to claim 1 or claim 2.

2. A heat fusion fitting comprising a body comprising at least a first layer of a first cross-linked polymeric material, a second layer of a second polymeric material, and a ferromagnetic heating element, the ferromagnetic heating element being embedded or partly embedded in the second layer and having a Curie temperature equal to or greater than the crystalline melting point or softening point of the second polymeric material.

3. A fitting according to claim 2, in which the first layer is an outer layer of the body, the second layer is an inner layer of the body and the insert is positioned internally of the body.

4. A fitting according to claim 2 or claim 3, in which the body of the fitting is of hollow tubular construction.

16. A fitting according to claim 2, in which there is still some unresolved recovery in the body region surrounding the ferromagnetic heating element.

18. A kit of parts for the manufacture of a heat fusion fitting which comprises:

(i) an insert which comprises a ferromagnetic heating element embedded or partly embedded in a fusible polymeric material, the ferromagnetic heating element having a Curie temperature equal to or greater than the crystalline melting point or softening point of the polymeric material; and

(ii) a body adapted to receive the insert, the body comprising at least a first layer of a first cross-linked polymeric material.

19. A kit of parts for the manufacture of a heat fusion fitting which comprises:

(i) an insert which comprises a ferromagnetic heating element embedded or partly embedded in a fusible polymeric material, the ferromagnetic heating element having a Curie temperature equal to or greater than the crystalline melting point or softening point of the polymeric material; and

(ii) a body adapted to receive the insert, the body comprising at least a first layer of a first recoverable polymeric material.