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Causes of grinding vibration marks and their solutions
Add Time:2020-10-22
There are two reasons for grinding vibration lines
  One type is the forced vibration of the workpiece,
  The other type is that the processing parameters are unreasonable, causing self-excited vibration of the workpiece.
  The first type of vibration exists in the environment. Even if no grinding is carried out, and the grinding machine is started, these vibrations will exist. It happens that some of the vibration frequencies are close to the resonance frequency of the workpiece, causing grinding chatter marks. Suspicious parts that produce these vibrations include bearings installed on rotating parts, belts for transmission, and hydraulic parts.
  The second category is that the effect during processing has periodic changes, and its frequency matches the resonance frequency of the workpiece, causing chatter marks. This kind of vibration can be reduced by adjusting the processing parameters. Or choose a grinding wheel with a lower hardness and a coarser grain size. Because if the rigidity of the grinding machine is lower than the price, using a sharp grinding wheel to reduce the grinding force can also reduce the vibration lines to a certain extent.
  "Optimizing the grinding process to prevent surface chattering" thesis (masterpiece of the grinding machine) How to solve the grinding chattering?
  When the grinding machine is grinding, if the surface of the ground product appears chattering or spiral, the reasons are various, and you can find it according to the following conditions:
  1. The method of dressing the grinding wheel is inappropriate.
  The gold fountain pen should be sharp, and the particles should not be loose. The cooling fluid should be sufficient during dressing, and the dressing amount of the finishing wheel should not be too large.
  2, whether the diamond pen is loose
  If the diamond pen for correcting the grinding wheel becomes loose, the surface of the repaired grinding wheel will naturally be uneven, and the surface quality of the ground product is inevitable.
  3. The grinding feed rate should be selected reasonably according to the workpiece allowance.
  Removal method: The grinding feed rate should be selected to keep the workpiece margin suitable, especially the workpiece margin during rough grinding.
  4. The straightness error of the bed guide rail or the grinding wheel carriage guide rail in the horizontal plane is large, which affects the dressing track.
  Remedy: The installation position of the diamond drill, try to make the dressing position the same as the grinding position.
  5. The large clearance of the grinding wheel spindle bearing reduces the stiffness that affects the dynamic effect.
  Remedy: Check the bearing clearance and adjust it if it is too large.
  6. The rigidity of the head and tailstock is poor, and the contact between the top hole of the supporting workpiece and the small end of the top produces poor supporting rigidity.
  Grinding between the centers of the rotating spindle, the headstock can be adjusted to zero, and the tailstock sleeve can be repaired if the gap is too large.
  7. The material of the workpiece and the grinding wheel do not match, so that the grinding wheel cannot effectively remove the workpiece, and it is severely passivated.
Elimination method: The material of the workpiece must be reasonably matched to the material of the grinding wheel: For example: the material of the workpiece is nickel, chromium steel, carburized steel, and tool steel. The hardness is KH; the hardness of general steel is LJ, and the tensile strength of cast iron and brass is relatively high. Low material selection black silicon carbide. Green silicon carbide is used for cemented carbide.
  This material should be matched with super hard grinding wheel.
  8. Is the rotation speed of the grinding wheel spindle and the workpiece spindle stable?
  Check whether the rotation speed of the grinding wheel spindle and the workpiece spindle is stable: When diagnosing the spindle rotation speed, let the checked spindle be given a speed, and you can check whether it is changing and how much it is changing from the diagnosis parameters of the spindle controller. You can also use a tachometer to measure speed. If the spindle speed is unstable, the surface of the ground workpiece will appear corrugated.
  9. Whether the heat dissipation fan of the grinding wheel spindle and workpiece spindle motor vibrates. The heat dissipation fan of the main motor directly affects the surface quality of the grinding product.
  10. Inspection of grinding head
  Measure the radial jump and axial movement of the grinding head. If it exceeds the standard, technical measures must be taken. If the diameter of the grinding head exceeds the standard value, if the grinding head cannot be replaced, the viscosity of the spindle oil of the grinding head can be increased to alleviate the impact of the disadvantages of the grinding head on the grinding product.
  11, bedside box claw and self-positioning board
During the rotation of the workpiece to be ground, if the pawl of the headstock has a relative displacement with the workpiece to be ground; if the self-positioning plate of the headstock slides intermittently during the rotation of the workpiece, the surface quality of the ground workpiece will be greatly affected. Big impact.