Cross spiral traces appear on the surface The reason for this kind of trace is mainly due to the poor straightness of the generatrix of the grinding wheel and the existence of unevenness. During grinding, the grinding wheel and the workpiece are only in partial contact. Helical and visible to the naked eye. The pitch of these helical lines is related to the speed of the workpiece table and the rotational speed of the workpiece, and is also related to the non-parallel relationship between the axis of the grinding wheel and the guide rail of the worktable. ►The main reason for the formation of the helix 1. The grinding wheel is poorly dressed, the corners are not chamfered, and no coolant is used for dressing; 2. There is too much lubricating oil in the guide rail of the workbench, causing the workbench to float; 3. The accuracy of the machine tool is not good; 4. Excessive grinding pressure, etc. ►Specific reasons for the formation of the helix 1. The rigidity of the V-shaped guide rail is not good. When grinding, the grinding wheel is offset, but the edge of the grinding wheel is in contact with the working surface; 2. When dressing the noisy wheel, the reversing speed of the worktable is unstable and the precision is not high, so that the dressing of a certain edge of the grinding wheel is slightly less; 3. The rigidity of the workpiece itself is poor; 4. There are broken and peeled sand grains on the grinding wheel and iron filings from the grinding of the workpiece are accumulated on the surface of the grinding wheel. For this reason, the repaired grinding wheel should be washed or brushed with cooling water; 5. The dressing of the grinding wheel is not good, and there are local protrusions, etc. Fish scales appear on the surface The main reason for reappearing fish scale marks on the surface is that the cutting edge of the grinding wheel is not sharp enough, and the phenomenon of “gnawing” occurs during grinding, and the vibration is large at this time, resulting in workpieces. ►The specific reasons for fish scale marks appearing on the surface are: 1. Garbage and oil dirt on the surface of the grinding wheel; 2. The grinding wheel is not rounded; 3. The grinding wheel becomes dull. The trimming is not sharp enough; 4. The diamond fastening frame is not firm, the diamond shakes or the quality of the diamond is not sharp; 5. Uneven hardness of the grinding wheel, etc. Working surface roughening The main reason for the reappearance of rough marks on the surface is that after the coarse-grained abrasive grains fall off, the abrasive grains are sandwiched between the workpiece and the grinding wheel. ►The specific reasons why the workpiece surface is roughened during grinding are: 1. The marks left over from rough grinding are not removed during fine grinding; 2. Coarse abrasive particles and tiny abrasive particles in the coolant are not filtered cleanly; 3. When the coarse-grained grinding wheel is just dressed, the abrasive grains are easy to fall off; 4. The validity period of the material toughness or the grinding wheel is too soft; 5. Improper coordination between abrasive grain toughness and workpiece material toughness, etc. There are straight wave traces on the surface of the workpiece We cut a cross-section of the center line of the vertical axis of the ground workpiece and enlarge it, and we can see that its periphery is similar to a sine wave. Make its center along the axis without rotation and translation, the track around the sine wave is the waveform cylinder, also known as polygon. The reason for the straight waveform is that the movement of the grinding wheel relative to the workpiece or the periodic change of the pressure of the grinding wheel on the workpiece grinding causes vibration. This kind of vibration may be forced vibration or self-excited vibration, so there are often more than one direct wave frequency on the workpiece. ►Specific reasons for a straight waveform trace are: 1. The clearance of the grinding wheel spindle is too large; 2. The hardness of the grinding wheel is too high; 3. The static balance of the grinding wheel is not good or the grinding wheel is blunt; 4. The workpiece speed is too high; 5. The horizontal knife is too big 6. The bearing of the grinding wheel spindle is worn, and the matching clearance is too large, resulting in radial runout; 7. Grinding wheel pressing mechanism or table “crawling”, etc.  

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