초록 ▼

A method of lubricating the wall surfaces of a die cavity used in powder metallurgy involves spraying the wall surfaces with tribocharged particles of a lubricant material. The method is carried out by means of an apparatus centered about a plug member which has a three-dimensional shape conforming

A method of lubricating the wall surfaces of a die cavity used in powder metallurgy involves spraying the wall surfaces with tribocharged particles of a lubricant material. The method is carried out by means of an apparatus centered about a plug member which has a three-dimensional shape conforming generally to that of the article to be formed. The plug member is slightly smaller than the article so that when the plug member is inserted into the die cavity there is a small, but uniform, gap created between the outer wall surfaces of the plug member and the walls of the die cavity. The plug member is secured to a closing plate which can be inserted into the die cavity so as to be sealed therewith. The closing plate is provided with vent holes and the plug member has a plurality of spaced apart tubes extending therethrough, which tubes exit at one or more of the wall surfaces of the plug member. The lubricant material is fed using an inert gas under pressure through tubing which tribocharged the lubricant particles and the tribocharged particles are sprayed from the tubes in the plug member into the gap so that they are electrostatically attracted to the walls of the die cavity and adhere thereto. Any excess gas and lubricant exits the gap through the vent holes in the closing plate. A uniform thin coating of lubricant is created on the walls of the die cavity. The green density of the article formed in the die is greater, and the ejection force required to remove the formed article from the die cavity is less, than with existing methods and apparatus.

대표청구항 ▼

[ What is claimed is:] [1.]1. Apparatus for lubricating a wall surface of a die cavity in which a powder will be compacted to form a three-dimensional article and from which the article will be ejected, the die cavity having walls defining the shape of the article, said apparatus comprising: a plug

[ What is claimed is:] [1.]1. Apparatus for lubricating a wall surface of a die cavity in which a powder will be compacted to form a three-dimensional article and from which the article will be ejected, the die cavity having walls defining the shape of the article, said apparatus comprising: a plug member having a three-dimensional shape generally conforming to that of said article, said plug member being insertable into said die cavity with a narrow gap between the walls of said cavity and adjacent outer wall surfaces of said plug member; a closing plate to which said plug member is secured; means for moving said plug member into said cavity and outwardly therefrom, said closing plate closing said die cavity when said plug member is within said die cavity; a plurality of tubes spaced apart adjacent the periphery of said plug member, extending therethrough and exiting at one or more of said outer wall surfaces of said plug member; means for supplying tribocharged particles of a lubricant material to said tubes using a pressurized inert gas; and venting means in said plate; whereby lubricant material is fed under pressure to said tubes and into said gap when said plug member is within said die cavity so that the lubricant material is electrostatically attracted to all wall surfaces of said cavity and excess gas and lubricant is vented from said gap via said venting means.