Current Situation of Tungsten Carbide Mould Design
Carbide drawing die is a simple structure mould.Before 1980s,we always abide by the "straight line" theory from Soviet,till 1980s,a fews factories accepted the technical theory"Smooth Transitions" proposed in 1950s to produce the wire drawing dies.
Recent years,Chinese scholars put forward of the max and min drawing angle concept by means of taking theoretical analysis of the carbide wire drawing dies in terms of angle design and groove-circling wear issues,as well as analysis of the uneven wear mechanism happend in the mould when the metal deformed in drawing process.Especially,the researchers from Guangdong Industrial Institute did anatomical analysis for the tungsten carbide dies for heading of small types screws,found out the secret why the Japan-made mould service life is 4~5 million times more than the home-made ones,the key point is the angle design,as the Japan-made moulds taken double-convex design in the contacting position between mould core bottom and mould sleeve inner hole center bottom face,whose advantage is to make the center position that bears the max force pressed tightly,in addtion the gap left around it available to be used for interference fit and store the excessed metales extruded from the hole walls.For instance,Shenyang Briage factory changed the structure of M12 carbide heading dies from initial 6 angles to 6 parts integrated to use,its average service life is 0.5 million pieces per mould,the max one is 1.2 million pieces.This is very reasonable design with 3 merits as following:
1)It saves much more tungsten carbide materials than the solid structure mould.
2)Easy assembly.
3)Easy K/D and replace of the broken one.
