What are the common faults of milling machines? How to exclude?
Generally speaking, its common faults are as follows:
Fault 1: The machined surface is not flat at the tool connection.
Solution: Check the parallelism of the worktable, the parallelism of the main axis relative to the worktable, and the verticality of the lifting table relative to the worktable.
Fault 2: The operating handle of the main shaft gearbox automatically falls off.
Solution: Replace the spring or add a gasket.
Fault 3: The operating handle of the main shaft gearbox cannot be operated.
Solution: the vertical shaft handle and the hole are stuck, remove and repair; the sector gear and the clip are stuck, adjust the gap to about 0.15mm; the fork shaft is bent and deformed, and straighten it; the rack shaft deviates from the hole cover Hole, change the speed of other levels, move the speed change plate, adjust the positioner spring.
In addition to the above faults, there is another major fault of the milling machine that cannot be ignored, that is, abnormal machining accuracy. This fault is highly concealed and difficult to diagnose. Then how should we solve it?
According to experts, there are five main reasons for this failure, which are:
First, the feed unit of the milling machine is changed or changed;
Second, the zero offset of each axis of the milling machine is abnormal;
Third, the axial backlash is abnormal;
Fourth, the motor running status is abnormal, that is, the electrical and control parts are abnormal;
Fifth, mechanical failures, such as screw, bearing, shaft coupling and other components are faulty.
In addition to the above five aspects, the preparation of processing programs, tool selection or human factors, etc., can also cause abnormal milling machine processing accuracy. Let's analyze some of them below.
(1) Change or modification of system parameters
What are the system parameters? The system parameters mainly include milling machine feed unit, zero offset and backlash. Some treatments in the repair process of the milling machine will affect the zero offset and backlash, so after the treatment, appropriate adjustments or modifications should be made. In addition, severe equipment wear or loose connections may also change the actual measured values of the parameters, so the parameters must be modified accordingly.
(2) Mechanical failure
There are several possible causes, such as the abnormality of the motor, the gap of the lead screw and the mechanical failure, so it is necessary to investigate one by one.
(3) The electrical parameters of the milling machine are not optimized, and the motor runs abnormally
There are two reasons for this: the screw backlash is large and the X-axis motor works abnormally. The solution is to compensate for the existing gap, adjust the servo gain parameters and pulse suppression function parameters, and eliminate the jitter of the X-axis motor.