Main shaft heating and rotation accuracy decrease
Fault phenomenon: the main shaft heats up quickly, and the machining produces a lot of noise. The hole accuracy and cylindricity of the processed parts can not meet the requirements.
Fault analysis: there may be four reasons for this phenomenon: the first reason may be that the lubricating grease used for the main shaft bearing is unqualified, or the impurities such as dust and moisture are mixed in it, which will reduce the bearing lubrication effect, generate a large amount of heat and noise, and cause the main shaft to heat too fast. The reason why there are impurities mixed into the lubricating grease may be that the machining center did not rectify and dry the compressed air during the pneumatic chip cleaning. The second reason may be that the positioning surface of the tapered hole inside the spindle used to position the tool was damaged during the process of tool drawing and inserting for many times, resulting in the perfect matching between the taper surface of the spindle and the taper surface of the tool shank, and the machined hole had a small eccentric error. The third reason may be that the preload of the front bearing of the main shaft decreases, resulting in a larger clearance of the bearing. The fourth reason may be the fatigue failure of the spring of the automatic clamping device inside the spindle after long-term use, resulting in the tool can not be fully tensioned and deviates from the original position.
Treatment method: if the front end bearing of the main shaft is damaged, it needs to be replaced, and qualified lubricating grease must be used, and the bearing clearance must be adjusted to prevent the bearing from being worn again; Install air fine filter and drying device to prevent impurities from mixing into lubricating grease; Grind the positioning surface of the tapered hole in the main shaft and use the color coating method to detect. Ensure that the contact surface between the positioning surface of the tapered hole and the tool shank is not less than 90%; If the clamping device spring fails, it must be replaced and the preload of the bearing shall be adjusted.
The pull rod steel ball of the main shaft component is damaged
Fault phenomenon: the tail cone surface of the tool shank of the pull rod steel ball tool of the tool automatic clamping mechanism in the spindle is frequently damaged.
Fault analysis: through research, it is found that the main reason for this problem is that the tool loosening action of the spindle is not coordinated with the tool pulling action of the manipulator. When the clamping mechanism is not fully loosened, the manipulator performs violent tool pulling, which seriously damages the pull rod steel ball and the tensioning screw. This is because the limit switch is installed at the tail of the booster cylinder. When the piston of the cylinder moves in place, the piston of the booster cylinder cannot be in place in time.
Treatment method: clean the oil cylinder and the cylinder, replace the sealing ring and adjust the pressure to make the piston action of the cylinder and the booster cylinder coordinated. In addition, regularly check the gas-liquid booster cylinder to eliminate the potential safety hazard in time.
The positioning key of the spindle component is damaged
Fault phenomenon: the machining center will make a lot of noise when changing the tool, and the positioning key at the front end of the spindle to rotate the tool handle is partially deformed.
Fault analysis: the noise generated during tool change is generated during the tool insertion stage of the manipulator, which is caused by the deviation of the spindle's Quasi stop position and the drift of the reference point for tool change of the spindle. The fixing screws of the orientation detection device of the machining center are easy to loosen after long-term use, which may cause the keyway of the tool handle and the positioning key on the spindle to be misaligned when the manipulator inserts the tool, and the positioning key may be damaged. The drift of the spindle tool changing reference point may be caused by poor contact of the circuit board of the CNC system, changes in electrical parameters, looseness of the proximity switch, etc.