Slewing ring in the grinding process, the working surface is carried out by a high-speed rotating grinding wheel, so if you do not follow the operating instructions for operation and adjustment of equipment, there will be all kinds of defects at the time of grinding work in slewing bearing surface, which affects the overall quality of the slewing ring. Slewing ring when precision grinding, due to the rough demanding work traces the surface grinding can often be observed on its surface grinding marks are the following to the naked eye.
Manifestations cross spiral traces
The main reason for this is due to traces of the grinding wheel straight busbar poor, there is a phenomenon of unevenness, when the grinding wheel and the workpiece is only partially in contact, when the workpiece or the grinding wheel several times back and forth movement of the workpiece cross-reproduction performance will helix and can be observed visually. Pitch and speed of these spiral workpiece table, the size of the workpiece speed, but also with the wheel axis is not parallel to the rail line and the related table.
Mainly due to the formation of the helix
1, Dresser bad, not chamfered corners, unused coolant for trimming.
2, table guide rails too much oil, causing the table to float.
3, machine precision is not good.
4, the grinding pressure is too large.
The reason is formed having a helix
1, V-shaped rail rigidity is bad, when an offset grinding wheel, but the wheel in contact with the edge of the work surface.
2, table dressing noisy when changing the wheel to speed instability, accuracy is not high, so that the edge of the grinding wheel dressing a little less.
3, the workpiece itself, poor rigidity.
4, the wheel had broken iron too flaking grits and workpiece grinding wheel attached to the under surface of the product, for which a good grinding wheel dressing should wash or scrub clean with cold water.
5, dressing well, there is a local projection and so on.
Surface appears scaly
The main reason scaly surface traces of reproduction is not enough because of the grinding wheel cutting edge sharp, the occurrence of “eating to live” phenomenon at the time of grinding, then a larger vibration. Specific causes the surface appears scaly marks are:
1, the wheel surface garbage and oil composition.
2, wheel untrimmed round.
3, wheel blunt. Dressing sharp enough.
4, diamond-bracket is not strong, the poor quality of diamond or diamond shaken not sharp.
5, uneven wheel hardness.
The main reason nap surface traces reproduction is due to coarse-grained grit off, sandwiched between the workpiece and the abrasive wheel caused. Specific reasons for surface grinding was napping at the time was:
1, when the legacy of kibble marks, not worn when grinding.
2, coolant coarse grains and tiny abrasive filter is not clean.
3, the coarse-grained abrasive wheel just trimmed off easily.
4, the material toughness is valid or wheel too soft.
5, grit and toughness and workpiece material toughness inappropriate
Waveform traces a straight surface
We milled workpiece cross-section perpendicular to the axis, and an enlarged cross-sectional, similar to a sine wave can be seen its periphery. Its center along the axis of rotation without translation, the trajectory is the sine waveform surrounding cylinder, which is also known as a polygon. The reason is that the waveform produce linear movement of the wheel relative to the workpiece or the pressure of the grinding wheel on the workpiece caused by the occurrence of cyclical changes in the exigencies of vibration. Such vibrations may be forced vibration, it may be self-excited vibration, and therefore often more than one straight wave frequency on the workpiece. Specific causes direct waveform traces are:
1, the wheel spindle gap is too large.
2, wheel hardness is too high.
3, wheel static balance wheel well or blunt.
4, the workpiece speed is too high.
5, lateral Qi knife too.
6, the wheel spindle rotary bearing wear, the gap is too large, resulting in runout.
7, wheel clamping mechanism or workbench “crawl” and so on.
Surface reproduction burns
Surface during the grinding process often burns, burns There are several types, one burns along the wheel machining direction, dark black patches. Second, was the line or intermittent line shape. Workpiece surface is burned in grinding process, summed up in the following reasons:
1, the wheel too hard or too dense tissue size too small.
2, the feed excessive, inadequate supply of cutting fluid, thermal conditions are poor.
3, the workpiece speed is too low, wheel speed too fast.
4, wheel runout is too large, constantly changing due to the grinding depth and burns.
5, Dresser is not timely or dressing well.
6, diamond sharp, dressing well.
7, when the workpiece burns too deep rough grinding, fine grinding allowance is too small, does not wear off.
8, or inadequate suction workpiece clamping force, under the grinding force, the workpiece presence stall phenomena.
Then the workpiece surface during grinding burn How do I know if it works? This is going to be checking out through regular pickling. After the workpiece pickling, on the surface moist, should immediately astigmatism lamp visual inspection, the normal surface is uniformly dark gray. The case of software, point-like dark clouds on the show black spots, and the perimeter of the indefinite integral. If decarbonization, is showing a dark gray or black spots. If the grinding crack, crack was the crack-like, in the case of burns, one surface showing dark black patches along the wheel machining direction, the second is rendered lines or discontinuous line shape. As appears above the grinding process burns phenomenon, must be timely to analyze the reasons, and take effective measures to solve them, to eliminate bulk burns.
The surface roughness below standard
Surface roughness slewing bearing parts are standard and process requirements, but in the grinding and ultra-fine process, due to various reasons, often not meet the requirements specified. Mainly the main cause of surface roughness is:
1, grinding speed is too low, too fast feed rate, feed is too large, no feed grinding time is too short.
2, the workpiece speed is too high or the workpiece axis and wheel shaft vibration is too large.
3, wheel size is too thick or too soft.
4, Dresser too fast or trimming mechanism gap is too large.
5, diamond grinding wheel dressing is not sharp or bad quality.
6, ultra-fine oil stone of poor quality, the installation position is incorrect.
7, ultra-refined kerosene below standard quality.
8, ultra-precision time is too short.