11 Numerical and Experimental Study on Orthogonal …
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micro-cutting test. During the cutting process of the micro-pit array tool, the cutting
force changes greatly, and the cutting force waveform changes more violently in a
sawtooth shape, which is caused by the increase in cutting force caused by “derivative
cutting”. When the chip flows through the surface of the micro-pit, the edge of the
micro-pit exerts a certain force on the chip passing through to perform “derivative
cutting” of the chip so that the cutting force increases.
Taking the average of the main cutting forces tending to be stable to obtain the
main cutting force of the non-textured tool F x = 60.7 N, the minimum cutting force
of the micro-pit tool of 35 µm is F x = 51.8 N, the cutting force of micro-pit array
cutters is less than that of non-textured cutters. Taking the average of the main cutting
forces tending to be stable to obtain the main cutting force of the non-textured tool F x
= 60.7 N, the minimum cutting force of the micro-pit tool of 35 µm is F x = 51.8 N.
The cutting force of micro-pit array cutters is less than that of non-textured cutters.
The cutting force fluctuations of the pit cutters of 30, 25 and 20 µm are large. This
is due to the increase in the strain of the chips when the “derivative cutting” of the
flowing chips is performed at the edge of the micro-pits. When the strain is greater
than the fracture limit of the chip, the chip fracture generates “C” type chips and
the cutting force decreases. The chipping force of 35 µm micro-pit tool is relatively
stable, and the cutting force is reduced by 14.7%. The fluctuation of the workpiece
and tool caused by “derivative cutting” is small, which reduces the machining error
and tool wear caused by the fluctuation of the workpiece or tool. It can be seen that
the effect of the change in the diameter of the micro-pits on the cutting force is also
different, and the size parameters of the micro-pits need to be properly designed
when the tool micro-pit array is placed. Under the premise of ensuring the storage
of chips and chip breaking in “derivative cutting”, it is also necessary to reasonably
control the size and change of cutting force to reduce cutting fluctuations.
11.3.3 Comparative Analysis of Cutting Temperature
Figure 11.6 shows the change in tool temperature during the cutting process. The
average cutting temperature of the non-textured tool is T 1 = 159.7 °C. The cutting
temperature of 35 µm micro-pit tool is T 2 = 159.9 °C. The cutting temperature of
30 µm micro-pit tool is T 3 = 162.2 °C. The cutting temperature of 25 µm micro-pit
cutter is T 4 = 160.9 °C. The cutting temperature of 20 µm micro-pit cutter is T 5
= 161.5 °C. Tool temperature change is not obvious. This is due to the “derivative
cutting” effect of the micro-pit texture tool during the cutting process. The interaction
of the chip and the bottom surface increases the friction force, so that the cutting
temperature is not significantly reduced. It can be seen that, when placing the tool
micro-pits, it is necessary to design the size parameters of the micro-pits reasonably
to reduce the cutting temperature changes caused by “derivative cutting”.
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micro-cutting test. During the cutting process of the micro-pit array tool, the cutting
force changes greatly, and the cutting force waveform changes more violently in a
sawtooth shape, which is caused by the increase in cutting force caused by “derivative
cutting”. When the chip flows through the surface of the micro-pit, the edge of the
micro-pit exerts a certain force on the chip passing through to perform “derivative
cutting” of the chip so that the cutting force increases.
Taking the average of the main cutting forces tending to be stable to obtain the
main cutting force of the non-textured tool F x = 60.7 N, the minimum cutting force
of the micro-pit tool of 35 µm is F x = 51.8 N, the cutting force of micro-pit array
cutters is less than that of non-textured cutters. Taking the average of the main cutting
forces tending to be stable to obtain the main cutting force of the non-textured tool F x
= 60.7 N, the minimum cutting force of the micro-pit tool of 35 µm is F x = 51.8 N.
The cutting force of micro-pit array cutters is less than that of non-textured cutters.
The cutting force fluctuations of the pit cutters of 30, 25 and 20 µm are large. This
is due to the increase in the strain of the chips when the “derivative cutting” of the
flowing chips is performed at the edge of the micro-pits. When the strain is greater
than the fracture limit of the chip, the chip fracture generates “C” type chips and
the cutting force decreases. The chipping force of 35 µm micro-pit tool is relatively
stable, and the cutting force is reduced by 14.7%. The fluctuation of the workpiece
and tool caused by “derivative cutting” is small, which reduces the machining error
and tool wear caused by the fluctuation of the workpiece or tool. It can be seen that
the effect of the change in the diameter of the micro-pits on the cutting force is also
different, and the size parameters of the micro-pits need to be properly designed
when the tool micro-pit array is placed. Under the premise of ensuring the storage
of chips and chip breaking in “derivative cutting”, it is also necessary to reasonably
control the size and change of cutting force to reduce cutting fluctuations.
11.3.3 Comparative Analysis of Cutting Temperature
Figure 11.6 shows the change in tool temperature during the cutting process. The
average cutting temperature of the non-textured tool is T 1 = 159.7 °C. The cutting
temperature of 35 µm micro-pit tool is T 2 = 159.9 °C. The cutting temperature of
30 µm micro-pit tool is T 3 = 162.2 °C. The cutting temperature of 25 µm micro-pit
cutter is T 4 = 160.9 °C. The cutting temperature of 20 µm micro-pit cutter is T 5
= 161.5 °C. Tool temperature change is not obvious. This is due to the “derivative
cutting” effect of the micro-pit texture tool during the cutting process. The interaction
of the chip and the bottom surface increases the friction force, so that the cutting
temperature is not significantly reduced. It can be seen that, when placing the tool
micro-pits, it is necessary to design the size parameters of the micro-pits reasonably
to reduce the cutting temperature changes caused by “derivative cutting”.