Mold for injection molding of cutting tool inserts having air gap of controlled width and method of making such inserts

Abstract

A mold is provided for making a cutting tool insert from a material to be molded, the cutting tool insert having an edge defined by two intersecting surfaces. The mold includes a first surface, a second surface intersecting with the first surface to define an edge, and an air gap between the first surface and the second surface at the edge, the width of the air gap varying in a controlled way along its length. A method for making a cutting tool insert is also disclosed.

1 . A mold  21  for making a cutting tool insert from a material to be molded, the cutting tool insert having an edge defined by two intersecting surfaces and, comprising: a first surface, a second surface intersecting with the first surface to define a edge, and an air gap between the first surface and the second surface at the edge, wherein the width of the air gap varies in a controlled way along its length. 
     
     
         2 . The mold as set forth in  claim 1 , wherein a minimum width of the air gap is 0-5 μm. 
     
     
         3 . The mold as set forth in  claim 2 , wherein a maximum width of the air gap is up to 0-5 μm. 
     
     
         4 . The mold as set forth in  claim 1 , wherein a maximum width of the air gap is up to 0-5 μm. 
     
     
         5 . The mold as set forth in  claim 1 , comprising a sprue gate, wherein the width of the air gap varies as a function of distance from the sprue gate. 
     
     
         6 . The mold as set forth in  claim 1 , wherein the width of the air gap varies as a function of pressure at the edge. 
     
     
         7 . The mold as set forth in  claim 1 , wherein the width of the air gap varies as a function of characteristics of the material to be molded. 
     
     
         8 . The mold as set forth in  claim 1 , wherein the width of the air gap varies as a function of temperature of the material to be molded. 
     
     
         9 . A method for making a cutting tool insert in a mold  21  , the cutting tool insert having an edge defined by two intersecting surfaces and , comprising: injecting material for forming the cutting tool insert into a mold cavity having a first surface and a second surface, the first surface and the second surface defining an edge, and air escaping from the mold cavity through an air gap between the first surface and the second surface at the edge, wherein the width of the air gap varies in a controlled way along its length. 
     
     
         10 . The method as set forth in  claim 9 , comprising injecting material to be molded into the mold cavity through a sprue gate, wherein the width of the air gap varies as a function of distance from the sprue gate.