Heat fusion fitting

• US 6,585,924 B1
• Filed: 03/31/2000
• Issued: 07/01/2003
• 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: Harget, David Charles, Jarvenkyla, Jyri
• Primary Examiner(s): RAYFORD, SANDRA M
• Application Number:
  US09/423,345
• Time in Patent Office: 1,187 Days
• Field of Search: 264/230, 428/35.8, 428/36.91
• US Class Current: 264/230
• 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 method for the manufacture of a heat fusion fitting, which comprises:

i) forming a body of hollow, tubular construction comprising at least a first layer of a first cross-linked polymeric material,

ii) forming an insert by moulding a second polymeric material around a ferromagnetic heating element so that the ferromagnetic heating element is embedded or partly embedded therein, the moulded material extending axially of the ferromagnetic heating element to form in-situ pre-moulded “

cold zones”

to contain the flow of melt from a melt region, the ferromagnetic heating element having a Curie temperature equal to or greater than the crystalline melting point or softening point of the second polymeric material, and

iii) assembling the body and the insert to form the fitting by expanding the body at a temperature below the crystalline melting point or softening point of the first polymeric material to impart a degree of dimensional recoverability to the body, such that the body, or a portion thereof, can recover from a larger diameter to a smaller diameter and thereby engage the insert which is positioned in the direction of recovery.

2. A method according to claim 1, in which the first layer is an outer layer of the body and the insert is positioned internally of the body.

3. A method 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.

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

5. A method according to claim 1, in which the first polymeric material is polyethylene, an ethylene copolymer, PVC, or a modified PVC.

6. A method according to claim 1, in which the first polymeric material is cross-linked to an extent of from 30% to 95%.

7. A method according to claim 2, in which the fitting is an in-line coupling and only the end sections of the coupling are expanded.

8. A method according to claim 2, in which the expansion of the body is in the range of from 15% to 45%.

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

10. A method according to claim 1, in which the ferromagnetic heating element is of generally tubular construction and is inwardly radially deformable.

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

12. A method according to claim 2, in which the moulded material is extended axially of the ferromagnetic heating element to form end sections adapted to perform further functions.

13. A method according to claim 1, in which the moulded material is extended axially of the ferromagnetic heating element to form end sections which are provided with internal grooves for accommodating sealing means.

14. A method 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.

15. A method according to claim 1, in which the dimensions of the expanded body and the insert are such that there is still some unresolved recovery in the body after it has recovered into contact with the insert.