Process for producing gripping elements for sealing and restraint systems for fluid pipelines and pipe joints produced thereby

1. A method for manufacturing a hardened gripping element for a sealing and restraint system used for forming a pipe joint in a water or sewer fluid pipeline of the type used in the waterworks industry, the method comprising the steps of:

providing a starting material comprised of an interfacially modified particulate and polymer composite material, the starting material comprising a metal particulate phase and a polymer phase;

forming a green metal composite article by either extruding the starting material or molding the starting material into a metal polymer composite article having at least one gripping surface having a plurality of gripping teeth;

thermally debinding and sintering the green metal composite article to produce a finished or near finished hardened gripping element; and

wherein the finished hardened gripping element is further characterized as having a linear shrinkage of less than 10%.

2. The method of claim 1 , wherein the metal composite body is formed by an extrusion process.

3. The method of claim 1 , wherein the metal composite body is formed by molding using either a compression molding or injection molding process.

4. The method of claim 1 , wherein the particulate comprise particles of stainless steel and the polymer is comprised of a polyolefin polymer.

5. The method of claim 4 , wherein the metal particulate phase makes up greater than 80% by weight of the particulate mix.

6. A method for manufacturing a hardened gripping element for a sealing and restraint system used for forming a pipe joint in a water or sewer fluid pipeline of the type used in the waterworks industry, the method comprising the steps of:

providing a starting material comprised of an interfacially modified particulate and polymer composite material, the starting material comprising a metal particulate phase and a polymer phase;

creating a three dimensional printed metallic mold of the gripping element that is to be manufactured;

forming a green metal composite article by injection molding the starting material mix in an injection molding machine into the three dimensional metallic mold to thereby form a metal polymer composite article having at least one gripping surface having a plurality of gripping teeth;

in a single step, thermally debinding and sintering the green metal composite article to produce a near finished hardened gripping element;

finish machining the hardened gripping element to form a finished hardened gripping element; and

wherein the finished hardened gripping element is further characterized as having a linear shrinkage of less than 10%.

7. The method of claim 6 , wherein the particulate phase is made up of stainless steel particles.

8. The method of claim 6 , wherein the polymer phase is a polyolefin polymer.

9. The method of claim 6 , wherein the particulate phase makes up at least 80% by weight of the metal polymer composite mix.

10. The method of claim 6 , wherein the finished hardened gripping element is further characterized as having a linear shrinkage of 8.6% or less.

11. A method forming a sealed and restrained pipe joint between two sections of plastic pipe in a water or sewer fluid pipeline of the type used in the waterworks industry, the method comprising the steps of:

providing a starting material comprised of an interfacially modified particulate and polymer composite material, the starting material comprising a metal particulate phase and a polymer phase;

creating a three dimensional printed metallic mold of the gripping element that is to be manufactured;

forming a green metal composite article by injection molding the starting material mix in an injection molding machine into the three dimensional metallic mold to thereby form a metal polymer composite article having at least one gripping surface having a plurality of gripping teeth;

thermally debinding and sintering the green metal composite article to produce a near finished hardened gripping element;

if necessary, finish machining the near finished gripping element to produce a finished element;

incorporating the finished metal composite article into a sealing and restraint system where the metal composite article is paired with a sealing gasket to thereby form a sealing and restraint system;

installing the sealing and restraint system into a mouth region of a section of belled plastic pipe;

installing a male pipe end into the mouth region of the section of belled plastic pipe to thereby form a sealed and restrained pipe joint; and

wherein the finished hardened gripping element which is used in the sealing and restraint system is further characterized as having a linear shrinkage of less than 10%.

12. The method of claim 11 , wherein the metal composite body is formed by an extrusion process.

13. The method of claim 11 , wherein the metal composite body is formed by molding using either a compression molding or injection molding process.

14. The method of claim 11 , wherein the particles are formed of stainless steel and the polymer phase is comprised of a polyolefin polymer.

15. The method of claim 11 , wherein the metal particulate phase makes up at least 80% by weight of the particulate mix.