High-speed ball screw design

Ball screw driving speed v = Ph × N (Ph is lead, N is screw revolving speed), thus there are two ways to increase the driving speed: one is to improve the revolving speed of the screw, and the second is to use large lead ball screw. Increase the revolving speed, subject to the do, N values (do is the ball screw nominal diameter). The international general screw revolving speed is less than 70000r/min.

When the screw speed increases, the nominal diameter must be reduced and the excessive increase speed will cause screw fever, resonance and other issues; nominal diameter too small can also cause the system poor rigidity, deformation, affect the machining accuracy, and the current servo motor only the highest speed to 4000r/min. When the lead is too large, not only increases the difficulty of manufacturing the ball screw, precision is difficult to improve, reducing the lead screw bearing, but also increases the servo motor starting torque. Thus, when designing high-speed ball screw to reasonably select the screw speed, nominal diameter and lead.

CNC machine tools ball screw design structure: the outer loop intubation type, the inner loop inverter type. Since the high-speed ball screw lead is larger, if use the inner loop structure, the inverter size is longer, reduce the number of bearing balls, and the ball fluency is poor at high speed, is not suitable; and the outer loop intubation type structure is simple, large bearing capacity, without restriction of lead. Therefore, it was selected as the high-speed ball screw structure.

There are three main preloaded ways of outer circulation ball screw: increased ball diameter, displacement lead and gaskets. High-speed ball screw design, lead, thread, loop selection are very important, directly affect the ball screw speed, load, life and so on.

Source: http://www.machineballscrew.com High Speed Ball Screws.