(1) Fever question

Because the linear micro motor is directly located inside the machine tool with poor heat dissipation conditions, the heat generated by the primary and secondary windings during the electromagnetic energy conversion process can easily increase the temperature T; Moreover, the increase of T will lead to an increase in the resistance value R of the motor winding. At this time, in order to ensure that the driving force output remains unchanged, the current I needs to be increased. Conversely, the increase of I will cause T to rise, forming a vicious cycle of positive feedback process. Moreover, because the windings and iron cores of linear motors are attached to the machine tool guide rails, their results will severely lead to thermal deformation of the machine tool guide rails.

Compared with the transmission method of rotating motors, on the one hand, the use of fans on the motor's own shaft can effectively dissipate heat, and on the other hand, after the rotating motor is driven by screws and other means, the spatial distance from the machine tool guide rail is already far, so there is no problem of thermal deformation caused by this. Therefore, after selecting a linear stepper motor drive for the machine tool feed system, it is crucial to address the issue of heat dissipation.

(2) Questions about magnetic isolation and protection

Because the magnetic field of a rotary motor is closed, while that of a linear motor is open, and located near the machine tool worktable, magnetic materials such as workpieces, chips, and objects are easily attracted by the magnetic field, hindering their normal operation. Therefore, although the electromagnetic type is slightly better than the permanent magnet type, its magnetic shielding protection cannot be ignored. And it is also necessary to consider the protection of machine tool coolant, lubricating oil, etc.

(3) Doubts about load disturbance

Linear motor transmission control can only be fully closed-loop control. The change in the workload of the workstation (workpiece component, cutting force, etc.) is an external disturbance to a stable system. If the automatic adjustment is not good, it will cause the system to oscillate and become unstable.

Therefore, for the entire linear feed drive system, in addition to requiring the linear motor to have strong load-bearing capabilities, it is also necessary to have negative feedback for speed and orientation detection, as well as high-speed information transmission, calibration, and response capabilities. And the collision damping between guide rails should also be minimized as much as possible, such as using rolling guide rails or magnetic pad suspension guide rails. In addition, when increasing the capacity of linear motors, adding the weight of the workbench appropriately can have a certain effect on reducing its load disturbance coefficient.

(4) The question of self weight in straight feed

When a linear stepper motor is applied to a straight feed structure, it is necessary to handle the self-locking problem when the linear motor is powered off and the impact of gravity acceleration on it during power on operation due to the weight of the drag plate. Therefore, in addition to adding suitable balance weights (or using hydraulic supports) and adopting mechanical self-locking devices when power is cut off, it is also necessary to adopt corresponding measures on the servo drive control module.