cutting vibration
Cutting vibration usually occurs in turning of slender shafts, turning of thin-walled parts, etc. Once the vibration is intensified, there will be intense vibration with an amplitude of more than tens of μm, usually accompanied by a lot of noise. In the cutting process, the vibration may exceed 100 μm. Although it can be processed, obvious vibration scratches will remain on the machined surface, which is not allowed on the finished surface.
Picture the hazards of cutting vibration
Vibration generated during metal cutting is a very harmful phenomenon.
1. Affect the surface quality of parts
If vibration occurs during processing, there will be a relative displacement between the tool and the workpiece, which will cause vibration marks on the processed surface and seriously affect the surface quality and performance of the part;
picture
2. Reduce machine tool and tool life
During the cutting vibration, the process system will continue to bear the dynamic alternating load, the tool is easy to wear (even chipping), the connection characteristics of the machine tool are damaged, and even the cutting process cannot continue in severe cases;
3. Noise is harmful to the health of the operator
The noise generated in the vibration will also endanger the health of the operator.
In order to reduce vibration, sometimes the cutting amount has to be reduced, which reduces the production efficiency of machine tool processing.
Therefore, in order to ensure the normal operation of this kind of machining equipment, the control of cutting chatter becomes more and more important.
Classification of cutting vibration
Causes of cutting vibration
The vibration of the tool when cutting the workpiece requires the following three conditions to exist at the same time:
The first is that the rigidity of the process system including the tool is insufficient, resulting in a low natural frequency.
The second is that the cutting produces a sufficiently large external force,
The third is that the frequency of the external excitation force is the same as the natural frequency of the process system and then resonates.
How to Eliminate Cutting Vibration
(1) Solutions
The first is to reduce the cutting force to a minimum,
The second is to enhance the static rigidity of the tool system or the fixture and the workpiece as much as possible;
The third is to create another vibration inside the tool holder to disrupt the vibration frequency of the externally driven cutting force, thereby eliminating tool vibration.
(2) Countermeasures
1. The first is to reduce the cutting force to the minimum
(1) Use sharp blades to reduce cutting force
(2) When the cutting depth is constant, use a small tool nose arc radius
(3) For boring cutters with slender tool bars and turning slender shaft parts, 90-degree lead angle tools should be used
(4) For milling cutters with slender rods, round blade milling cutters are the most conducive to vibration reduction
(5) The plunge milling method is often used for milling deep cavities with slender rod end mills
(6) The face milling cutter adopts a coarse-tooth unequal distance milling cutter to reduce milling vibration
(7) The smaller the edge angle of the insert when boring the inner hole, the better
2. Improve the static rigidity of the tool holder (Static Toughness)
Use solid carbide or heavy metal shanks to increase the static rigidity of the shank
3. Improve the dynamic rigidity of the tool—passive damping and vibration-proof tool holder
