The ball screw slide module linear stage can be positioned repeatedly, can accurately record the accuracy, and achieve the best motion effect. Let's take a look at the accuracy requirements for repeated positioning.
The reproducibility of the screw slide positioning system refers to the degree of change in its actual position when trying to continuously pass a specific position. There is a highly repeatable system (the accuracy may be high, or it may not be high) repeatedly through the same given position, no matter which direction it is in, it shows extremely low position dispersion. The difference between moving one point in the same direction (repeatable in one direction), moving to one point in the opposite direction (two-way repeatability) and moving in the opposite direction. Generally speaking, the position changes in two-way movement are larger than that in one-way movement. Just look at the repeatability data of unilateral movement, the effect on the backlash is not obvious.
If the repeatability requirements are high, it is best not to use a lead screw and use a linear motor as an actuator. Although this requirement increases the use of linear encoders and both the slider and the servo controller need to work in closed-loop mode, their performance has been greatly improved because of the encoder's resolution and the inevitable thermal effect.
Although linear feedback sensors can be used to measure the characteristics of the closed-loop positioning system, when the open-loop or rotary encoder slide is repeatedly moved for many times, the lead screw will overheat due to friction, which will cause thermal expansion and contraction and position deviation . As a result, the repeatability data of the standard positioning sliding seat (not the entire servo system) obtained by this method will fully respond to the special characteristics of the lead screw and nut. Thermal expansion and contraction mainly depend on operating speed and duty cycle. If the time of the repeated test is too short, it will not be able to react to the influence of environmental temperature changes.
Although the method described above to eliminate the influence of thermal effects on measurement repeatability is too accurate, our purpose is to fully demonstrate that our anti{{0}}backlash nut (used with a lead screw-driven carriage) has inherent capabilities. Repeating characteristics. The results of extensive use of laser interferometry have shown that the typical unidirectional value is less than 0.5 microns (with many other products between 0.1 and 0.3 microns), and the bidirectional value does not exceed 1 micron (many products are between 0.2 and 0.3 microns). 0.5 microns). In addition, the anti-backlash nut design has self-compensating characteristics, even after long-term use, the repeatability value of the device drops below 5 microns.
It can be seen from the above that the ball screw slide table mold also has high requirements for repeated positioning accuracy, and the higher the accuracy.
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