Two basic methods for turning the CNC machining center back to zero and how to deal with common problems.
For CNC machine tools, it is an indispensable part of the zero return operation before each power-on operation. The function of this zero return operation is mainly to re-determine the origin and coordinates of the machine, and The term error is compensated.
First, the two basic methods of starting the machine to return to zero operation
Turning the zero back on is the operation that our machining personnel often use. However, some people may not know what is the power-on zero. In the popular way, the coordinates of the machine tool are returned to the initial position, and then the coordinate point is passed. As a reference point to achieve subsequent processing operations and task control. At the same time, the reference point can be provided to facilitate the adjustment of tool compensation and clearance compensation in the latter half of the machining. According to the implementation method and the detection device, the zero return method mainly has two kinds of grid methods and magnetic switches.
As the two main methods of zero return on the machining center, their effects and execution methods are completely different. Among them, in the case of magnetic switch returning to zero, this method has its zero return accuracy and effect due to the defect of its own positioning drift phenomenon, so this method is only applied in the early processing center, now The high-precision machining center is basically extinct.
The principle of grid method zero return is to realize the effective zero return of the machine tool through two parts of the grating ruler and the pulse encoder. This zero return method has high precision and good flexibility, and is the mainstream zero return mode of the current CNC machine tool; This method is divided into two parts: absolute grid method and incremental grid method. Absolute grid method means that the machine can permanently hold the zero position after completing the zero return operation in the first debugging process, and then it is not necessary to perform this step.
Second, the problem often occurs in machine tool zero return operation and its countermeasures
When zeroing the machining center, even if no changes are made to the system parameters, there will be occasional zero return failures. In our use, there are two kinds of faults that often occur. One is that the step of zero return is correct but the zero position is wrong; the other is that the zero return system is normal but the zero position cannot be found.
1, the zero return step is correct, but the zero position is incorrect.
The reasons for this type of fault may be included in three aspects: First, the parameter of the zero offset is not properly considered in the design; second, the time of zero return is too short, resulting in the position of the zero far exceeding the actual range. The third is that the mechanical structure in the zero return system results in a zero position offset. Knowing these three possible reasons, we can eliminate the problems that may cause the machining center to return to zero according to the actual situation.
2. The zero return system is normal but cannot find the fault at the zero position.
There are three main reasons for this type of fault: one is that the internal components of the operation control system are damaged; the other is that the circuit between the signal receiving system and the zero switch is damaged; the third is at the zero point. Caused by damage to the relevant switch. Knowing the above-mentioned possible reasons, we can leave out according to the actual situation on the spot to eliminate the cause of the zero return failure of the machining center.