Powder extrusion of shaped sections

Abstract

The present invention provides a continuous powder extrusion method for making an article having a profile including an outer shape and optionally including one or more inner hollows. One or more bulk material powders and one or more binders are provided, and the bulk material powders and the binders are mixed to form a mixture. A die is provided, the die optionally including a mandrel having one or more shapes. The mixture is extruded through the die and the optional mandrel to produce a green form. The green form is debound to produce a brown form and the brown form is sintered to produce a densified form. The densified form is optionally processed using thermal, mechanical, and / or thermomechanical processing to produce a wrought form. The densified or wrought form is optionally cut to a length and / or finished using traditional metal finishing processes.

Description

FIELD OF INVENTION [0001]The material and methods disclosed herein relate generally to powder metal processing, and in particular to a method for forming articles from metal or ceramic powders by continuous extrusion of shaped sections.BACKGROUND OF INVENTION [0002]Metal injection molding (MIM) has been practiced for years to produce articles for industries such as agricultural, automotive, business machine, food & beverage, hardware, medical, small appliance, and sporting goods. Metal injection molding is capable of producing articles that have material properties comparable to those of articles produced by forging, stamping, and machining processes, while at the same time providing the ability to produce high volumes of the articles in a cost effective manner. Additional advantages of metal injection molding include the ability to produce articles with intricate shapes, the ability to produce net and near net articles with close tolerances, and the ability to produce articles with...

AI Technical Summary

Benefits of technology

[0006]A powder extrusion method can be performed continuously, and can be used to make long lengths of net or near net forms with a custom-shaped cross section, or to make long lengths of preforms that can be thermally, mechanically or thermomechanically processed to produce non-molded articles. Continuous powder extrusion is a cost effective method of producing a non-molded article having precise features that may otherwise need to be machined from comparable cast and wrought material.

[0008]The continuous powder extrusion method can be used to produce shaped sections that are difficult or costly to fabricate by other methods, such as a section having an internal hexagonal or octagonal shape. The continuous powder extrusion method can further be used to produce shaped bars or tubes of custom materials, including reactive, brittle, or hard materials that may be difficult to melt and cast or reduce by traditional metal working processes including extrusion, forging, rolling, drawing or stretching. Additionally, the continuous powder extrusion method can be used to make sintered powder metal preformed shapes for subsequent hot forging or hot rolling operations to heal small internal voids and promote homogeneity, whereby the output of the combined processes is a low cost finished wrought product having a high density and similar mechanical properties to cast and wrought metal products. Additionally, the continuous powder extrusion method can be used to make custom materials that include more than one composition of metallic powders or both metallic and ceramic powders.

[0010]The present invention still further provides a method for making a non-molded article using powder extrusion. The method includes providing one or more bulk material powders, providing one or more binders, mixing the one or more bulk material powders and the one or more binders to make a mixture, and providing a die having a shape. The method further includes heating the mixture, extruding the mixture through the combination of the die and the mandrel to produce a green form having an outer profile corresponding to the shape of the die, and receiving the green form onto a setter tray. The method also includes debinding the green form to produce a brown form; sintering the brown form to produce a densified form, and processing the densified form to produce an article. The setter tray enables the brown form to shrink without fracturing.

Problems solved by technology

The continuous powder extrusion method can be used to produce shaped sections that are difficult or costly to fabricate by other methods, such as a section having an internal hexagonal or octagonal shape.

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