Joints for polymeric pipe

• US 5,776,293 A
• Filed: 05/02/1997
• Issued: 07/07/1998
• Est. Priority Date: 01/30/1995
• Status: Expired due to Term

• Current Assignee: Jerry C. Levingston
• Original Assignee: Jerry C. Levingston
• Inventors: Levingston, Jerry C.
• Primary Examiner(s): SELLS, JAMES D
• Application Number:
  US08/850,634
• Time in Patent Office: 431 Days
• Field of Search: 156/293, 156/308.2, 156/309.6, 156/309.9, 156/304.1, 156/304.5, 156/304.6, 156/499, 156/580, 156/583.1, 285/200, 285/382.4, 285/382.5, 285/382.7
• US Class Current: 156/304.6
• CPC Class Codes: B29C 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 65/2076 perpendicularly to the plane comprising the parts to be joined
• CPC Class Codes: B29C 65/305 involving the use of cartridge heaters
• CPC Class Codes: B29C 65/7802 Positioning the parts to be joined, e.g. aligning, indexing or centring
• CPC Class Codes: B29C 66/02242 Perforating or boring
• CPC Class Codes: B29C 66/1142 Single butt to butt joints
• CPC Class Codes: B29C 66/1162 Single bevel to bevel joints, e.g. mitre joints
• CPC Class Codes: B29C 66/5223 for forming corner connections or elbows, e.g. for making V-shaped pieces
• CPC Class Codes: B29C 66/52231 with a right angle, e.g. for making L-shaped pieces
• CPC Class Codes: B29C 66/5224 for forming fork-shaped connections, e.g. for making Y-shaped pieces
• CPC Class Codes: B29C 66/52241 with two right angles, e.g. for making T-shaped pieces
• CPC Class Codes: B29C 66/52298 said socket being composed by several elements
• 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 66/73921 characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/81422 being convex
• CPC Class Codes: B29C 66/81423 being concave
• CPC Class Codes: B29C 66/818 characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps characterised by the heating means B29C65/24; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps
• CPC Class Codes: B29C 66/91421 of the joining tools
• 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 66/91935 : lower than said fusion temperature
• CPC Class Codes: B29C 66/91945 : lower than said glass transition temperature
• CPC Class Codes: B29D 23/008 : T-joints
• CPC Class Codes: B29K 2023/04 : Polymers of ethylene
• CPC Class Codes: B29K 2023/06 : PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/065 : HDPE, i.e. high density polyethylene
• CPC Class Codes: B29L 2031/243 : Elbows
• CPC Class Codes: B29L 2031/246 : T-joints
• CPC Class Codes: Y10T 156/1066 : Cutting to shape joining edge surfaces only

Abstract

A method for forming a branch in a pipe made of polymeric material which permits a strong joint to be formed at the branch to another pipe. A system for carrying out the method includes heaters which soften the polymeric material in a highly localized manner. A forming member is pulled through the softened material to deform the pipe wall and form a branch. A method for making reinforced pipe joints in which pipe sections are force fit into each other is also disclosed.

Claims

1. A method for forming a branch in a pipe made of polymeric material comprising the steps of:

applying heat to a portion of a cylindrical exterior surface of the pipe wall;

applying heat to a portion of a cylindrical interior surface of the pipe wall generally radially opposite to the exterior surface portion of the pipe wall to which heat is applied;

said steps of applying heat being carried out for a sufficient period to render generally plastic the polymeric material in the pipe wall in a volume of the wall between said interior and exterior surface portions of the pipe wall;

positioning a forming member in the interior of the pipe in the proximity of the interior surface portion of the pipe wall, the forming member having a temperature less than the melting temperature of the polymeric material;

pulling the forming member through the plasticized volume of the pipe wall toward the exterior of the pipe;

forming polymeric material of the pipe which is displaced outwardly by the forming member as it is pulled through the volume to form the branch generally in the shape of a pipe section extending outwardly from the pipe wall.

2. A method as set forth in claim 1 wherein the step of pulling the forming member through the plasticized volume of the pipe wall comprises the steps of:

drawing the forming member through the volume until an opening in the pipe wall having a size corresponding to the size preselected for the branch is formed;

holding the forming member in the pipe wall for a time selected to permit the heated polymeric material to cool sufficiently to generally hold its formed shape;

removing the forming member from the opening.

3. A method as set forth in claim 2 wherein the step of forming the polymeric material which is displaced by the forming member comprises the step of mounting a forming collar on the exterior surface of the pipe wall, and wherein the step of drawing the forming member through the plasticized volume of the pipe wall comprises the step of drawing the forming member into the collar with the displaced polymeric material located between the forming member and collar.

4. A method as set forth in claim 3 wherein the steps of applying heat to the exterior and interior surface portions of the pipe wall comprise the steps of applying a first heater having a concave heating face against the exterior surface portion of the pipe wall so that the heating face conforms to and is in substantially face-to-face engagement with the exterior surface portion, and applying a second heater having a convex heating face to the interior surface portion of the pipe wall so that the heating face conforms to and is in substantially face-to-face engagement with the interior surface portion.

5. A method as set forth in claim 4 wherein the forming member is generally at ambient temperature just prior to being pulled through the plasticized volume of the pipe wall.

6. A method as set forth in claim 1 wherein the steps of applying heat to the exterior and interior surface portions of the pipe wall comprise the steps of applying a first heater having a concave heating face against the exterior surface portion of the pipe wall so that the heating face conforms to and is in substantially face-to-face engagement with the exterior surface portion, and applying a second heater having a convex heating face to the interior surface portion of the pipe wall so that the heating face conforms to and is in substantially face-to-face engagement with the interior surface portion.

7. A method as set forth in claim 1 wherein the forming member is generally at ambient temperature just prior to being pulled through the plasticized volume of the pipe wall.

8. A method as set forth in claim 1 wherein the steps of applying heat to the exterior and interior surface portions of the pipe wall comprise the step of applying heat until the polymeric material in the volume between the exterior and interior surface portions is sufficiently soft to plasticly deform but is not tacky.

9. A method as set forth in claim 1 wherein the steps of applying heat to the cylindrical exterior and interior surface portions of the pipe comprise the steps of:

forming an opening through the pipe wall between the exterior and interior surface portions;

applying a first heater having a concave heating face against the exterior surface portion;

applying a second heater having a convex heating face against the interior surface portion;

interengaging the first and second heaters through the opening in the pipe wall.

10. A method as set forth in claim 9 wherein the step of interengaging the first and second heaters comprises the step of interconnecting the first and second heaters in clamping engagement with the exterior and interior surface portions of the pipe wall.

11. A system for forming a branch in a pipe made of polymeric material comprising:

fixture means for holding the pipe in a position;

a first heater having a concave heating face shaped for engaging a cylindrical exterior surface of the pipe wall over substantially the entire area of the heating face;

a second heater having a convex heating face shaped for engaging an interior surface of the pipe wall over substantially the entire area of the heating face, the first and second heaters being adapted to heat a volume of the pipe wall between the exterior and interior surfaces to make the material in said volume substantially plastic;

a forming member sized for forming an inside diameter of the branch to be formed;

puller means adapted for connection to said forming member for pulling the forming member through the volume generally from the interior of the pipe to the exterior of the pipe.

12. A system as set forth in claim 11 wherein further comprising a collar adapted for mounting on the exterior surface of the pipe wall, the collar being sized for receiving the forming member therein and for shaping polymeric material displaced from the pipe wall by the forming member to form an exterior surface of the branch.

13. A system as set forth in claim 12 wherein the forming member has a tapered leading end and a body adjacent the tapered end, the body being sized to form the inside diameter of the branch.

14. A system as forth in claim 13 wherein the body has a diameter larger than the inside diameter of the branch to be formed by the forming member.

15. A system as set forth in claim 11 further comprising a connector for interconnecting the first and second heaters through an opening in the pipe wall extending between the exterior and interior surfaces, the connector being capable of holding the first and second heaters in clamping engagement with the exterior and interior surfaces of the pipe wall.