Claims
- 1. A welding rod for welding adjacent members of thermoplastic material, comprising a solid homogeneous core of thermoplastic material and a resistance element enveloping said core and embedded in said rod just below a thin thermoplastic surface layer of said rod, wherein said resistance element comprises a wire helically wound in a surrounding relationship about said core in the lengthwise direction of said rod, and wherein said resistance element is embedded in said rod below the surface of said rod a sufficient depth such that burning of said thermoplastic during welding is substantially prevented when a welding current is applied to the resistance element, but not so deep that burning of the thermoplastic material of the core occurs prior to softening of portions of the adjacent members nearest the welding rod.
- 2. The welding rod of claim 1, wherein said welding rod has a generally round shape in cross-section.
- 3. The welding rod of claim 2, wherein said welding rod is ring-shaped.
- 4. The welding rod of claim 1, wherein said resistance element comprises a plurality of wires wound in parallel about said core in a helical configuration, each wire being spaced from each other wire along the length of said welding rod.
- 5. The welding rod of claim 4, further comprising a pair of terminals at each end of said rod, said wires being connected to said terminals at opposite ends thereof.
- 6. The welding rod of claim 4, wherein said wires comprise fine metal wires, and said thermoplastic surface layer forms a thin sheath about said core and said wires.
- 7. The welding rod of claim 6, wherein said thermoplastic surface layer has helical indentations therein which match the shape of said helically wound wires.
- 8. The welding rod of claim 1, wherein said welding rod is configured to be flexible enough so that it can be bent and formed into a rounded shape that traces the outline of surfaces of the members to be welded.
- 9. The welding rod of claim 1, wherein said thermoplastic is high-density polyethylene.
- 10. The welding rod of claim 9, wherein said resistance element wire is made of stainless steel.
- 11. The welding rod of claim 1, wherein said resistance element wire is made of stainless steel.
- 12. The welding rod of claim 1, wherein said resistance element is a fine metal wire, and said thermoplastic surface layer forms a thin sheath about said core and said wire.
- 13. The welding rod of claim 12, wherein said thermoplastic surface layer has a helical indentation therein which matches the shape of said helically wound wire.
- 14. The welding rod of claim 1, wherein said welding rod is ring-shaped.
- 15. A double electric welding rod for welding adjacent members of thermoplastic material comprising:
- a first welding rod and a second welding rod, each of said first and second welding rods comprising:
- a solid homogeneous core of said thermoplastic material, a resistance element comprised of a plurality of electrically conductive wires wound around said solid core, said resistance element and said solid core being coated with a thin layer of said thermoplastic material to embed said resistance element just below the layer of thermoplastic material on said solid core, said resistance element at a first end of said first welding rod connected to said resistance element at a first end of said second welding rod, said resistance element at a second end of said first welding rod connected to said resistance element at a second end of said second welding rod, and said first welding rod distanced from said second welding rod between said first and said second ends.
- 16. The double welding rod according to claim 15 wherein said wires are helically wound around said cores.
Parent Case Info
This is a divisional of Ser. No. 08/095,936, filed on Jul. 22, 1993, which is a continuation of Ser. No. 07/941,662, filed on Sep. 8, 1992, now abandoned, which is a continuation-in-part of Ser. No. 07/698,243, filed on May 6, 1991, abandoned, which is a continuation of Ser. No. 07/456,576, filed on Dec. 29, 1989, abandoned, which is a continuation-in-part of Ser. No. 07/152,016, filed on Feb. 3, 1988, abandoned.
US Referenced Citations (15)
Foreign Referenced Citations (6)
Number |
Date |
Country |
1072800 |
Mar 1954 |
FRX |
1416207 |
Sep 1965 |
FRX |
3204681 |
Aug 1983 |
DEX |
54-23029 |
Aug 1979 |
JPX |
56-161116 |
Dec 1981 |
JPX |
336980 |
Apr 1959 |
CHX |
Divisions (1)
|
Number |
Date |
Country |
Parent |
95936 |
Jul 1993 |
|
Continuations (2)
|
Number |
Date |
Country |
Parent |
941662 |
Sep 1992 |
|
Parent |
456576 |
Dec 1989 |
|
Continuation in Parts (2)
|
Number |
Date |
Country |
Parent |
698243 |
May 1991 |
|
Parent |
152016 |
Feb 1988 |
|