Abnormal troubleshooting and precision processing example
CNC machining process precision mechanical failure resulting in abnormal failure phenomenon: a SV-1000 vertical machining center, using Frank systems. Link mold machining process, suddenly found abnormal Z-axis feed, killing at least 1mm cutting error amount (Z direction overcut).
Troubleshooting: survey learned that failure is the sudden occurrence. Jogging machine, manually enter data in each axis mode operation under normal operation and normal reference point, no alarm, the possibility of electrical control hardware troubleshooting. Mainly on the following aspects should be checked one by one. . [Precision machinery parts processing, worthy of your attention]
Processing section while checking the accuracy of abnormal machine is running, especially the tool length compensation, processing coordinate system (G54-G59) proofreading and calculations.
In jog mode, repeated motion Z-axis, through visual, touch, hearing, diagnosis of their state of motion, found abnormal Z-motion noise, especially fast jog, noise is more pronounced. Judging mechanical hazards that may exist. Check the Z-axis machine tool accuracy. Move the Z-axis with manual pulse generator (as the gear ratio to 1 × 100, that changes every step motor feed 0.1mm), with a dial indicator to observe the movement of the Z-axis. After a one-way exercise to maintain normal forward movement as a starting point, every change is a step pulse, the actual distance d Z axis motion machine = d1 = d2 = d3 = ... = 0.1mm, indicates that the motor is running well, the positioning accuracy is also good . And the return to the actual movement of the machine changes the displacement can be divided into four stages:
(1) machine movement distance d1> d = 0.1mm (slope greater than 1);
(2) exhibits for d1 = 0.1mm> d2> d3 (slope of less than 1);
(3) The actual mechanism is not moving the machine, showing the most standard Backlash;
(4) and pulse the machine movement distance equal value is given by the (slope equal to 1), return to the normal movement of the machine. Whatever compensate for backlash, the exhibit features are: In addition to the three-phase compensation, other changes in the segments still exist, especially in the first stages of a serious impact on the machining accuracy. Compensation was found, the greater the backlash compensation, a stage moving distance is greater. [Precision machinery parts processing, worthy of your attention]
Analysis of the inspection think there several possible reasons:
One motor abnormalities, two are mechanical failure, three are screw gap. To further diagnose the problem, the motor and the screw is fully disengaged, respectively, motor and mechanical parts to be checked. Test results are normal motor running; in the mechanical part of the diagnosis found that the disk moving hand screw, the initial return movement has a great sense of vacancy. And under normal circumstances, should be able to feel the bearing orderly and smooth movement.
Troubleshooting: After disassembly inspection revealed that the bearing is really damaged, and there is a ball off. Machine back to normal after the replacement.