Application of Ball Screw on High Speed ​​CNC Machine Tool

High-speed machining is a high-paying technology oriented to the 21st century. It is characterized by high efficiency, high precision, and surface quality. It has become increasingly popular in aerospace, automotive, tooling, optoelectronic engineering, and instrumentation. The application, and has achieved significant technical and economic benefits, is an important part of contemporary advanced manufacturing technology. In order to achieve high-speed machining, high-speed CNC machine tools are first required. High-speed CNC machine tools must have both a high-speed spindle system and a high-speed feed system to achieve high-speed material cutting. In order to realize high-speed feed, manufacturers at home and abroad have continuously taken measures to improve the high-speed performance of the Ball Screw. The main measures are:

Appropriately increase the screw speed, lead and thread number. At present, the matching of the nominal lead diameter and lead of a large-lead ball screw is: 400mm*20mm, 50mm*25mm, 50mm*30mm, etc., and the feed rate can reach 60m/min or more. In order to improve the rigidity and load-carrying capacity of the ball screw, the large-lead ball screw generally adopts double-headed threads to increase the number of effective Bearing cycles of the ball.

Improve the structure and improve the smoothness of ball movement. Improve the ball circulation reversal device, optimize the curve parameters of the return ball groove, adopt the three-dimensional shape of the guide tube and the return ball device, truly introduce the ball into the nut body along the lead angle of the internal thread, so that the ball moves The direction is tangent to the raceway rather than intersecting. This minimizes shock losses and noise.

Hollow forced cooling technology. High-speed ball screws generate high temperatures due to friction during operation, resulting in thermal deformation of the screw, directly affecting the machining accuracy of high-speed machine tools. Hollow forced cooling technology is used to pass the constant temperature cutting fluid into the hole of the hollow screw to perform forced cooling of the ball screw and keep the temperature of the ball pair constant. This measure is an effective way to improve the high speed performance and working accuracy of medium and large ball screws.

For a high-speed feed system with a large stroke, a screw-fixed, nut-rotating drive can be used. At this time, the nut rotates while moving axially along the fixed screw. Since the screw does not understand, the limitation of the critical rotation speed can be avoided, and various problems occurring when the slender ball screw rotates at high speed can be avoided. The nut has low inertia, flexible movement and high rotational speed.

Further improve the manufacturing quality of ball screw. By adopting the above measures, some problems in the transmission ball screw can be overcome to some extent. Its maximum fast moving speed can reach 60m/min, and in some cases it can even reach 90m/min and the acceleration can reach 15m/s2. Because the ball screw has a long history, mature technology, wide application, and low cost, it is still not very high in the middle load bearing, the feed rate is not very high, the general high-speed machining center and other economical high-speed CNC machine tools whose travel range is not too large are still Often used.