First, the defects and measures that are easy to produce during curve grinding
Curve grinding on a surface grinder often results in defects such as surface ripples, burns, scratches, patterns, and wear scars (filaments). For these problems, the following measures can be taken:
1. Most of the surface corrugation is caused by the vibration of the grinding wheel, such as excessive bearing clearance, spindle misalignment, poor motor rotor dynamic balance, and uneven oil film between the main shaft and the bearing. In addition, if the wheel is not well balanced, it will also generate ripples. If the grinding wheel is well balanced and there are still ripples, then the grinding wheel and its mating parts must be repaired or adjusted to completely eliminate the ripple phenomenon.
2. When processing materials with high hardness, the grinding wheel has poor grinding efficiency, and the grinding point will produce high temperature, which is easy to burn the workpiece (for example, when grinding W18Cr4V, it is more likely to burn). In order to prevent burns, there must be sufficient grinding fluid at the grinding point. In addition, the amount of back-to-eat knives should be appropriate and should not be too large. A good method is to reduce the linear speed of the grinding wheel, which is about 18m/s. The low speed of 1440r/min on the M7120A grinder basically eliminates burns. Another advantage of reduced wheel speed is the reduction of wheel frame vibration, which in turn reduces and eliminates ripples.
3. There are two kinds of scratches in the curve grinding: one kind of scratch has no regularity, which is the impureness of the grinding fluid, the impurities and the abrasive particles are washed and scratched between the grinding wheel and the workpiece. The method of eliminating such scratches requires grinding fluid filtration, generally using magnetic and copper mesh three-way filtration; the other scratching is like a dotted line, shallow, and the length is about the same, this is the grinding wheel grinding When the grain is about to fall off, it is scratched as the wheel rotates. The elimination method at this time is to use a sufficient grinding fluid when trimming the grinding wheel, and to fix the two end faces of the grinding wheel into a narrow oblique shape in the outer width. In addition, the selection of the grinding wheel should be appropriate, not too soft, do not use a grinding wheel that is too self-sufficient.
4. When the curve is milled, the pattern shapes that are easy to appear have various forms. There are also many factors that cause the pattern. The main reason is the vibration caused by the vibration of the grinding wheel, the external influence and the vibration of the adjacent machine tool. When the grinding wheel is too blunt, the pattern will appear when the stroke is unstable. When the adjacent machine tool is not being used for grinding, the pattern is less likely to appear.
5. When the wear scar (filament flow) in the curve grinding is obvious, to remove the filament flow, it is necessary to use a fine-grained grinding wheel. However, when using a fine grinding wheel, the following points must be considered:
(1) When finishing the grinding wheel, the diamond knife should be sharp, the grinding fluid should be sufficient, and the debris should be washed away in time to avoid affecting the surface of the grinding wheel.
(2) Grinding should be appropriate to prevent surface burns and other defects and affect the surface. Be careful to leave the proper grinding allowance.
(3) The line speed of the grinding wheel must be reduced to 15~18m/s.
(4) The grinding fluid is carefully filtered to prevent scratching.
(5) When grinding the grinding wheel with grindstone, the contact area between the grinding stone and the grinding wheel should not be too small, and the grinding stone used should not be too soft, otherwise the effect of the finishing wheel will not be achieved.