Method of molding double-layer sliding bearing

Abstract

A method of molding a double-layer sliding bearing made of a sintered double-layer green compact comprises an inner layer and an outer layer. A circular bearing surface is formed on either an inner periphery of the inner layer or an outer periphery of the outer layer, wherein either the inner layer or the outer layer with the bearing surface is defined as a first layer that has a thinner wall thickness and a higher forming density than the other layer without the bearing surface defined as a second layer. The invention provides molding processes for the reinforced and perforated first layer and also for the double-layer green compact to combine a prepared first layer with a compressed powder forming the second layer.

What is claimed is: 
     
         1 . A method of molding a double-layer sliding bearing made of a sintered double-layer green compact, comprising:
 an inner layer and an outer layer, a circular bearing surface being formed on either an inner periphery of the inner layer or an outer periphery of the outer layer;   wherein either the inner layer or the outer layer with the bearing surface is defined as a first layer that has a thinner wall thickness and a higher forming density than the other layer without the bearing surface defined as a second layer;   wherein the double-layer green compact is formed by molding the first layer in advance and loading the first layer in a cavity of a mould before filling a powder forming the second layer therein;   wherein a predetermined axial length of a filled powder of the second layer is longer than a length of the first layer, and compressing only on the filled powder to a length equal to the length of the first layer.   
     
     
         2 . The method of molding the double-layer sliding bearing of  claim 1 , wherein said molding the first layer comprises the steps of:
 filling a powder forming the first layer into a cavity of a mould with an axial length of a filled powder longer than the length of the first layer;   compressing the filled powder to a length equal to the length of the first layer.   
     
     
         3 . The method of molding the double-layer sliding bearing of  claim 1 , wherein the first layer includes at least two units, in which two adjacent end faces between each pair of two adjacent units of the at least two units are in contact with each other;
 wherein molding each of the at least two units comprises the steps of:   filling a powder forming the first layer into a cavity of a mould with an axial length of a filled powder of the first layer longer than a length of each of the at least two units;   compressing the filled powder to a length equal to the length of each of the at least two units with a same diameter of the bearing surface and a same wall thickness as the first layer;   wherein said molding the first layer comprises the steps of:   loading the at least two units arranged in an axially butted manner into the cavity with a total length of the at least two units longer than the length of the first layer;   compressing the at least two units to a length equal to the length of the first layer.   
     
     
         4 . The method of molding the double-layer sliding bearing of  claim 3 , wherein said loading the at least two units arranged in an axially butted manner into the cavity with a total length of the at least two units longer than the length of the first layer further includes at least one penetrating notch, which is radially indented on at least one of two adjacent end faces between at least one pair of two adjacent units of the at least two units, and compressing the at least two units to a length equal to the length of the first layer. 
     
     
         5 . The method of molding the double-layer sliding bearing of  claim 1 , wherein molding the double-layer green compact comprises the steps of:
 preparing a dummy part with a same diameter of the bearing surface and a same wall thickness as the first layer;   loading the first layer and the dummy part into the cavity axially and making the bearing surface against a wall of the cavity;   filling the powder forming the second layer into a remaining space of the cavity to a length equal to the predetermined axial length which is equal to a total length of the first layer and the dummy part;   compressing the filled powder to a length equal to the length of the first layer.   
     
     
         6 . The method of molding the double-layer sliding bearing of  claim 1 , wherein molding the double-layer green compact comprises the steps of:
 preparing an annular groove with an axial depression formed on the mould to fit just right for accommodating the first layer therein;   loading the first layer in the annular groove;   filling the powder forming the second layer into a remaining space of the cavity to a length equal to the predetermined axial length;   compressing the filled powder to a length equal to the length of the first layer.