CNC milling machine cutting process, the cause of many processing errors, caused by the tool runout which is an important factor, which directly affects the smallest machine in ideal shape error processing conditions can be achieved and the machined surface geometry accuracy. In the actual cutting, the radial runout tool affect machining accuracy, surface roughness, unevenness and cutting tool wear process characteristics multi-tooth cutter. Tool runout, the more unstable the processing status of the tool, the more influence the processing results.
Second, the runout causes
Manufacturing error and the tool spindle unit, clamping error caused by drift and eccentricity between the tool and the spindle axis over the axis of rotation, as well as specific processing technology, tooling and so may produce CNC milling tool in the processing of the runout.
1, spindle runout itself the impact
The main reason spindle runout are concentricity error of each spindle journal, various errors of the bearing itself, concentricity error between the bearings, shaft deflection, etc., which the spindle rotation accuracy radial effect size with different processing methods and different. These factors are the machine manufacturing and assembly process of the formation as a machine operator is difficult to avoid the impact they bring.
2, spindle rotation tool center and the center of the impact of inconsistent
During the installation of the tool to the spindle, if the center of rotation of the tool and the spindle center inconsistent, will inevitably bring the tool runout. Specific factors are: the tool and chuck with, knife method is correct and the quality of the tool itself.
3, the impact of the specific process
Radial tool during processing to produce mainly because of the beating radial cutting forces intensified runout. Radial cutting force is the total cutting force in the radial direction of the force. It will make the workpiece deformation and bending vibration during machining is the main component affect the quality of the workpiece. It is mainly influenced by the amount of the cutting tool and the work piece of material, tool geometry, lubrication and processing methods and other factors.
Third, the method of reducing runout
Tool runout generated during processing is mainly due to radial cutting forces intensified runout. Therefore, to reduce the radial cutting force is reduced runout important principle. You can use several methods to reduce runout:
1. Use a sharp knife
Use a larger rake angle and sharper the tool to reduce cutting forces and vibration. After the selection of a large tool angle decreases flank and the workpiece main surface of the tool after the transition elastic restoring the friction between the layers, which can reduce the vibration. However, the anterior horn and posterior horn of the tool can not be selected too large, otherwise it will lead to insufficient strength of the tool and the heat dissipation area. So, in conjunction with the specific circumstances of the use of different anterior horn and posterior angle of the tool, you can take a small number of roughing, but in the finishing, the tool for reducing the radial runout aspect to consider, you should get larger, the tool more sharp.
2, using high-intensity tools
The main strength of the tool can be increased in two ways. One can increase the diameter of the holder subject to the same in the case of radial cutting forces, the shank diameter of the 20% increase in radial runout of the tool can be reduced by 50%. Second, it could reduce the projected length of the tool, the tool extends the greater the length, the greater the tool deformation processing, the processing in constant change, the radial runout of the tool will follow the ever-changing, causing the workpiece machined surface is not smooth Similarly, extending the length of the tool is reduced by 20%, radial runout of the tool will be reduced by 50%.
3, the tool rake face should be smooth
During processing, it can be reduced smooth rake face of the tool chip of friction to be reduced by the tool cutting forces, thereby reducing the radial runout of the tool.
4, spindle taper and chuck clean
Spindle taper collet and clean, can not have debris and dust produced when machining the workpiece. Selection of cutting tools, try using a shorter length of the extended cutter knife, the intensity should be reasonably uniform, not too big or too small.
5, the choice of cut to be reasonable
When the amount is too small knife to eat, there will be slipping phenomenon processing, resulting in the tool changing radial runout during processing, so that processing of the surface is not smooth excessive eating knife, cutting force will become larger, thereby cause deformation tools, increasing the tool when machining radial runout, also make the processing of the surface is not smooth.
6, when using conventional milling finishing
Because when climb milling, the gap between the nut and the screw position is changed, it will cause uneven feeding table, so there is shock and vibration, impact tools, machining tool life and surface roughness of the workpiece in use when milling, cutting thickness from small to large, the tool load is also from small to large, the tool is more stable during processing. Note that this only when finishing use, or to use climb milling during roughing. This is because the production of high climb milling and tool life can be guaranteed
7, rational use of cutting fluid.
Rational use of aqueous cutting fluid to cool the main action has little effect on the cutting forces. In the main cutting oil lubrication can significantly reduce the cutting force. Because of its lubricating effect, can reduce the friction between the chip and the tool rake face and the flank transition between the surface and the workpiece, thereby reducing tool runout.
Practice has proved that as long as each part of the machine manufacturing, assembly accuracy, choose the right technology, tooling, tool radial runout on the workpiece machining accuracy can be generated by reducing the maximum extent possible.
Second, the runout causes
Manufacturing error and the tool spindle unit, clamping error caused by drift and eccentricity between the tool and the spindle axis over the axis of rotation, as well as specific processing technology, tooling and so may produce CNC milling tool in the processing of the runout.
1, spindle runout itself the impact
The main reason spindle runout are concentricity error of each spindle journal, various errors of the bearing itself, concentricity error between the bearings, shaft deflection, etc., which the spindle rotation accuracy radial effect size with different processing methods and different. These factors are the machine manufacturing and assembly process of the formation as a machine operator is difficult to avoid the impact they bring.
2, spindle rotation tool center and the center of the impact of inconsistent
During the installation of the tool to the spindle, if the center of rotation of the tool and the spindle center inconsistent, will inevitably bring the tool runout. Specific factors are: the tool and chuck with, knife method is correct and the quality of the tool itself.
3, the impact of the specific process
Radial tool during processing to produce mainly because of the beating radial cutting forces intensified runout. Radial cutting force is the total cutting force in the radial direction of the force. It will make the workpiece deformation and bending vibration during machining is the main component affect the quality of the workpiece. It is mainly influenced by the amount of the cutting tool and the work piece of material, tool geometry, lubrication and processing methods and other factors.
Third, the method of reducing runout
Tool runout generated during processing is mainly due to radial cutting forces intensified runout. Therefore, to reduce the radial cutting force is reduced runout important principle. You can use several methods to reduce runout:
1. Use a sharp knife
Use a larger rake angle and sharper the tool to reduce cutting forces and vibration. After the selection of a large tool angle decreases flank and the workpiece main surface of the tool after the transition elastic restoring the friction between the layers, which can reduce the vibration. However, the anterior horn and posterior horn of the tool can not be selected too large, otherwise it will lead to insufficient strength of the tool and the heat dissipation area. So, in conjunction with the specific circumstances of the use of different anterior horn and posterior angle of the tool, you can take a small number of roughing, but in the finishing, the tool for reducing the radial runout aspect to consider, you should get larger, the tool more sharp.
2, using high-intensity tools
The main strength of the tool can be increased in two ways. One can increase the diameter of the holder subject to the same in the case of radial cutting forces, the shank diameter of the 20% increase in radial runout of the tool can be reduced by 50%. Second, it could reduce the projected length of the tool, the tool extends the greater the length, the greater the tool deformation processing, the processing in constant change, the radial runout of the tool will follow the ever-changing, causing the workpiece machined surface is not smooth Similarly, extending the length of the tool is reduced by 20%, radial runout of the tool will be reduced by 50%.
3, the tool rake face should be smooth
During processing, it can be reduced smooth rake face of the tool chip of friction to be reduced by the tool cutting forces, thereby reducing the radial runout of the tool.
4, spindle taper and chuck clean
Spindle taper collet and clean, can not have debris and dust produced when machining the workpiece. Selection of cutting tools, try using a shorter length of the extended cutter knife, the intensity should be reasonably uniform, not too big or too small.
5, the choice of cut to be reasonable
When the amount is too small knife to eat, there will be slipping phenomenon processing, resulting in the tool changing radial runout during processing, so that processing of the surface is not smooth excessive eating knife, cutting force will become larger, thereby cause deformation tools, increasing the tool when machining radial runout, also make the processing of the surface is not smooth.
6, when using conventional milling finishing
Because when climb milling, the gap between the nut and the screw position is changed, it will cause uneven feeding table, so there is shock and vibration, impact tools, machining tool life and surface roughness of the workpiece in use when milling, cutting thickness from small to large, the tool load is also from small to large, the tool is more stable during processing. Note that this only when finishing use, or to use climb milling during roughing. This is because the production of high climb milling and tool life can be guaranteed
7, rational use of cutting fluid.
Rational use of aqueous cutting fluid to cool the main action has little effect on the cutting forces. In the main cutting oil lubrication can significantly reduce the cutting force. Because of its lubricating effect, can reduce the friction between the chip and the tool rake face and the flank transition between the surface and the workpiece, thereby reducing tool runout.
Practice has proved that as long as each part of the machine manufacturing, assembly accuracy, choose the right technology, tooling, tool radial runout on the workpiece machining accuracy can be generated by reducing the maximum extent possible.