A multi head screw factory tutor teaches you how to inspect and repair screw rods

a) Inspection and maintenance of single nut pairs

For single nut ball screws, the gap between the screw and nut pairs cannot be adjusted. If there is a gap detected in the screw nut pair. Firstly, check whether the thread arcs of the lead screw and nut have been worn. If the wear is severe, the complete set of lead screw nuts must be replaced.

If there is slight wear during inspection, a larger diameter ball can be replaced for repair. Firstly, detect the large clearance of the screw nut pair, convert it into an increase in the diameter of the ball, and then select a suitable ball for reassembly. This type of maintenance is quite complex, requires a long time, and requires a high level of technical proficiency.

b) Gap caused by loose connection between nut flange and workbench

This problem is generally easily overlooked, as the machine tool moves back and forth for a long time, causing gaps in the screws that fix the Faraday disc. When checking the clearance between the screw and nut, it is important to first eliminate this fault factor to avoid taking a detour during repair.

c) Repair of faults such as unstable movement and excessive noise in the ball screw nut pair.

The uneven movement and excessive noise of the ball screw nut pair are mostly caused by poor lubrication, but sometimes it may also be caused by the servo motor driving parameters not being adjusted properly.

The main steps in the assembly and adjustment of ball screws

In general, during the assembly process of machine tools, attention should be paid to the position of the joint surface of the ball screw. After determining the position, the position of the ball screw should be installed. In addition, it is important not to completely tighten the fixing bolts. The gap between the two joint surfaces should not be too large and can be checked using a 0.02mm feeler gauge, which means that the feeler gauge cannot be inserted. Attention should be paid to measuring the hole assembly inspection sleeve, inspection rod and other components involved in the ball screw. The position of the motor base should be confirmed through a certain ruler to ensure that it is on the positive reference plane of the two sliders of the ball screw linear guide rail. Then, a ruler should be used to measure the position of the dial gauge base used to place the dial gauge. Specifically, it is to push the seat of the dial gauge to a position where the measuring head of the dial gauge can contact the surface of the inspection rod, and then pay attention to zeroing the pointer of the dial gauge measuring the high point.

Hard milling thread technology has been studied in Europe for many years, and a CNC cyclone milling machine was launched in the 1980s. It has now been widely used in ball screw thread processing, and the thread grinding process has been basically abandoned. The hard milling process has a shorter process and can take 3-5 fewer steps than traditional grinding processes. According to statistics, traditional grinding processes account for two-thirds of the thread grinding time in the entire process flow. The thread grinding process includes rough grinding of threads, bottom groove grinding of threads, and precision grinding of threads. These processes are all ground using a thread grinder after the ball screw has reached a quenching hardness of 58-62HRC. Based on the limitations of thread grinding cutting amount, the grinding wheel and straightening of the screw need to be constantly adjusted during the grinding process, resulting in longer working hours; The hard milling thread process is a one-time forming milling of the thread raceway, which not only reduces the number of processes, but also eliminates the need for repeated tool trimming and straightening, to a certain extent reducing the proportion of thread processing time, thereby greatly shortening the ball screw processing cycle and improving processing efficiency.