This paper will talk about the faults and maintenance methods of linear guide rail.
(1) Maintenance of motor overheating alarm
Fault phenomenon: X-axis motor overheating alarm
Analysis and treatment process: there are many reasons for the motor overheating alarm. In addition to the problems of the servo unit itself, it may be unreasonable cutting parameters or problems in the transmission chain. The fault reason of the machine tool is that the gap between PI Ruijian linear guide strip and guide rail is too small and adjusted too tightly. Loosen the insert locking screw, adjust the insert bolt to make the moving parts move flexibly, ensure that the 0.03mm feeler gauge cannot be inserted, and then lock the locking screw. Troubleshooting.
(2) Maintenance of obvious mechanical vibration fault at the end of travel
Fault phenomenon: when a machining center is running, the obvious mechanical vibration fault occurs when the displacement of the workbench in the x-axis direction approaches the end of the stroke, and the system does not alarm when the fault occurs.
Analysis and treatment process: because the system does not alarm when the fault occurs, but the fault is obvious, it is determined that the fault position should be on one side of x-axis servo motor and lead screw drive chain through exchange inspection. In order to distinguish the motor fault, the elastic coupling between the motor and the ball screw can be disassembled, and the motor can be powered on and checked separately. The inspection results show that there is no vibration when the motor is running, and it is obvious that the fault is in the mechanical transmission part. Disconnect the elastic coupling and turn the ball screw with a wrench for hand feeling inspection; Through the hand feeling inspection, it is found that the resistance increases significantly when the x-axis displacement of the worktable approaches the end of the stroke. After dismantling the workbench for inspection, it is found that the ball screw is not parallel to the guide rail, which causes vibration during mechanical rotation. After careful repair and adjustment, reinstall and eliminate the fault.
(3) Fault maintenance caused by loose ball screw nut
Fault phenomenon: the z-axis of the machine tool vibrates (the square ram is Z-axis), and the No. 123 alarm appears instantly; The machine stops running.
Analysis and treatment process: the reason for the No. 123 alarm is that the tracking error exceeds the value specified in the machine tool data ten345 / n346.
There are three possibilities for this phenomenon:
① The detection device of the position measurement system is poorly connected with the mechanical displacement part.
② There is a gap in the transmission part.
③ The position closed-loop amplification factor kV does not match.
Through detailed inspection and analysis, it is preliminarily concluded that the latter two reasons cause the load disturbance during the operation of the square ram (Z-axis) and cause the position closed-loop oscillation. Based on this judgment, we first modified the machine tool data tenl52 for setting the z-axis kV coefficient, and changed the original value s1333 to S800, that is, the amplification coefficient is reduced, which is conducive to the stability of the position closed-loop: it is found that although the vibration phenomenon is obviously weakened, it is not completely eliminated after the test run. This shows that the possibility of clearance in mechanical transmission increases; It may be that the ram insert is loose and the ball screw or nut moves. For each part of the machine tool, the method of first easy then difficult, first external and then internal negation one by one is adopted. Finally, the fault source is found out: the back cap of the ball screw nut is loose, resulting in a gap in the transmission. When the z-axis moves, the position closed-loop oscillation is caused by the load disturbance caused by the gap, resulting in jitter. Tighten the loose back cap, adjust the clearance, and restore the machine tool data tenl52 to the original value, and then the fault is eliminated.
(4) Fault maintenance of mechanical interference during movement
Fault phenomenon: a machining center adopts a linear rolling guide rail. After installation, use a wrench to rotate the ball screw for hand feeling inspection. It is found that obvious mechanical fault occurs during the movement of the workbench in the x-axis direction, with great movement resistance.
Analysis and treatment process: the fault is obvious in the mechanical structure. Remove the workbench, first check the parallelism between the ball screw and the guide rail, and the inspection is qualified. Then check the parallelism of the two linear guide rails, and it is found that the parallelism of the guide rails is seriously out of tolerance. Remove the two linear guide rails and check the parallelism of the installation base plane of SBC linear guide rail on the middle sliding plate, which is qualified. Check the linear guide rail again and find that the parallelism between the installation base surface of a linear guide rail and its raceway is seriously out of tolerance (0.5mm). Replace the qualified linear guide rail and remove the fault after reinstallation.
(5) Fault maintenance of unqualified positioning accuracy of machine tool
Fault phenomenon: when a machining center is running, the y-axis displacement of the worktable is close to the end of the stroke, the reverse clearance of the lead screw increases obviously, and the positioning accuracy of the machine tool is unqualified. Analysis and treatment process: the fault location is obviously on one side of x-axis servo motor and lead screw drive chain; Remove the elastic coupling between the motor and the ball screw, and turn the ball screw with a wrench for hand feeling inspection. Through the hand feeling inspection, it is found that the resistance increases significantly when the x-axis displacement of the worktable approaches the end of the stroke. After dismantling the workbench for inspection, it is found that the parallelism of y-axis guide rail is seriously out of tolerance, resulting in obvious increase of resistance during mechanical rotation, elastic deformation of ball screw, increase of reverse clearance, and unqualified positioning accuracy of machine tool. After careful repair and adjustment, reinstall and eliminate the fault.
