Process for joining powder injection molded parts

Patent metadata

Field	Value
Publication number	US-10226818-B2
Application number	US-40807809-A
Country	US
Kind code	B2
Filing date	Mar 20, 2009
Priority date	Mar 20, 2009
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

A process for joining two or more powder injection molded parts by preparing at least two green parts from a feedstock including a binder and an injection powder. Placing the two or more green part into intimate contact, and maintaining the two green parts in intimate contact at a position with a linkage between the at least two green parts to produce an interconnected green assembly. Placing the assembly under shape retaining conditions, melting the binder of the interconnected green assembly under shape retaining conditions to produce a seamless body.

First claim

The invention claimed is:

1. A process for joining powder injection molded parts, the method comprising:
preparing at least two green parts from a feedstock, the feedstock comprising a binder and an injection powder;
placing the at least two green parts in intimate contact while the binder is frozen; maintaining the at least two green parts in intimate contact with a linkage between the at least two green parts along contact surfaces defining a joint between the at least two green parts, to produce an interconnected green assembly;
placing the interconnected green assembly under shape retaining conditions;
producing a seamless brown part from the at least two green parts by first heating the interconnected green assembly to a temperature above the melting point of the binder but below the boiling point thereof, causing the binder to completely melt throughout the at least two green parts to eliminate the joint between the at least two green parts so that at least the two green parts join seamlessly while the binder is in a liquid phase; debinding the joined green parts so formed by removing the majority of the liquid binder away from the seamlessly joined green parts; and a second stage of heating to a temperature above the boiling point to then vaporize all the binder after the joining of the at least two green parts has been completed thus producing a brown part.

2. The process of claim 1 , wherein the assembly is disengaged and re-engaged before being placed under shape retaining conditions.

3. The process of claim 1 , wherein the maintaining step comprises a mechanical joining of the two green parts.

4. The step process of claim 3 wherein the step of mechanically joining the at least two green parts includes screwing the at least two green parts together at a threaded joint.

5. The process of claim 1 , wherein the maintaining step comprises heating at least a small portion of a contact surface of the at least one of the two green parts sufficiently to melt the binder.

6. The process of claim 1 , wherein the maintaining step comprises spot welding the at least two green parts using a laser or other heat source.

7. The process of claim 1 , wherein the maintaining step comprises heating the at least two green parts to a temperature where they stick to one another without melting.

8. The process of claim 1 , wherein the injection powder is a finely divided ceramic, metallic and/or carbide powder.

9. The process of claim 8 , wherein the injection powder is a metallic powder.

10. The process of claim 1 , wherein the at least two green parts are prepared by:
providing the binder and the injection powder;
thoroughly dispersing the binder and the injection powder together to produce a particulate feedstock;
heating the feedstock to melt the binder to produce the molten feedstock; and freezing the molten feedstock in at least one mould.

11. The process of claim 1 , wherein the injection powder for each of the green parts is a different composition.

12. The process of claim 1 , wherein the injection powder used for the green parts is a mix of powders of different nature and/or composition.

13. The process as defined in claim 1 wherein the process is stopped before all the binder has been evacuated in the first stage of heating; interconnecting a third green part by physical means to the partially co-debinded assembly to produce a complex green assembly; and placing the complex green assembly in the shape retaining conditions.

14. The process as defined in claim 13 wherein the process of de-binding is resumed.

15. The process as defined in claim 1 wherein the interconnected green assembly is placed within a bed of particulate material and the particulate material is compacted to ensure the shape retaining conditions.

16. The process of claim 15 , wherein the solid particulate material is alumina (Al 2 O 3 ) or alumina based.

17. The process of claim 15 wherein the solid particulate material is readily wetted by the binder to facilitate the wicking action of the particulate material on the binder.

18. The process as defined in claim 15 wherein the step of debinding the majority of the binder in liquid phase occurs by a wicking action of the bed of particulate material.

19. The process as defined in claim 15 including the further step of pre-sintering the brown part to allow the brown part to retain its shape after debinding.

20. The process as defined in claim 19 including the steps of cooling and then removing the pre-sintered brown part from the shape retaining bed of particulate material; and sintering the brown part.

21. The process as defined in claim 1 including the steps of engaging complementary mating structures provided on said at least two green parts to link the green parts in such a manner as to permit the at least two green parts to be readily disengaged; and verifying the alignment of the at least two green parts and if necessary disengaging and re-engaging the green parts.

Assignees

• Scalzo Orlando
• Campomanes Marc
• Despres Melissa
• Bouthillier Alain
• Savaria Vincent
• Pratt & Whitney Canada

Inventors

• Scalzo Orlando
• Campomanes Marc
• Despres Melissa
• Bouthillier Alain
• Savaria Vincent

Classifications

• B22F7/062

  involving the connection or repairing of preformed parts · CPC title

• B22F3/225 Primary

  by injection molding · CPC title