Attention to the use of the cutter die of the precision four column hydraulic cutting machine
1、 The form reason of tool wear
When cutting metal with four column cutting machine, on the one hand, the cutting tool will cut off the chip, on the other hand, the tool itself will be damaged. There are two main types of tool damage: wear breakage. The former is continuous progressive wear, while the latter includes brittle failure (such as chipping, breaking, spalling, crack damage, etc.) plastic damage. After tool wear, the machining accuracy of the workpiece is reduced, the surface roughness is increased, the cutting force, cutting temperature even vibration are caused, so the normal cutting can be continued. Therefore, tool wear directly affects machining efficiency, quality cost. The forms of tool wear are as follows:
Wear of rake face
Wear of rear cutter face
According to the temperature dependence, the main causes of normal tool wear are mechanical wear, thermal chemical wear. The mechanical wear of four column cutting is caused by the scratching effect of hard points in the workpiece material, while the thermal chemical wear is caused by adhesion (the combination phenomenon when the tool the workpiece material contact the distance between atoms), diffusion (the chemical elements on the two friction surfaces of the tool the workpiece face to each other, corrosion, etc.).
2、 Tool wear process, blunt standard tool life
The tool wear increases with the increase of cutting time. According to the cutting experiment, the typical wear curve of the tool in normal wear process can be obtained. The abscissa ordinate of the diagram are cutting time wear amount VB ( wear depth of crescent groove on front cutter face KT) as abscissa ordinate respectively. The tool wear process can be divided into three stages
Initial wear stage
Normal wear stage
Rapid wear stage
If the tool is worn to a certain limit, it can be used. This wear limit is called the blunt criterion. The actual cutting time of a new tool ( re sharpened tool) the beginning of use to reaching the blunt standard is called tool life.