The cutter wear increases as the cutting time increases. According to the cutting experiment, the typical wear curve of the normal wear process of the tool as shown in the following figure can be obtained. The figure takes the cutting time and the flank wear amount VB as the abscissa and the ordinate, respectively.
As can be seen from the figure, the cutter wear process of the cutting machine can be divided into three stages:
1. Initial wear stage
The cutters of the cutting machine have a quick initial wear process and a short time. The sharpening of the surface of a newly sharpened tool is prominent. During the friction with the chips, the pressure is not uniform, and the pressure at the peak is very large, causing the peak to be quickly worn away, so that the pressure tends to be even and the wear speed is slowed down.
2. Normal wear stage
The surface of the cutter of the cutting machine is initially worn, the peak point is smoothed, the pressure of the surface tends to be even, and the wear amount VB of the cutter increases uniformly with time. The wear curve at this stage is basically linear, and its slope represents the wear strength, which is an important indicator for comparing tool performance.
3. Rapid wear stage
After the normal wear stage of the cutter of the loader, the cutting edge has become dull, the cutting force and cutting temperature rise sharply, the cause of wear changes qualitatively, the surface of the tool is fatigued, the performance is degraded, the wear amount VB increases sharply, and the tool will quickly fail. .
Cutting machine tool blunt standard:
If the tool wears to a certain limit, it cannot be used any more. This wear limit is called the cutter blunt standard.
Cutting machine tool life:
The actual cutting time experienced by a new knife (or re-sharpened tool) from the start of use until the blunt standard is reached is called the tool life of the cutting machine.