Anchor rod

Anchor rod:

1) Anchor rod Process characteristics of screw structure

Lead screw is a slender flexible shaft, the ratio of length l to diameter d is large, generally 20~50, poor rigidity. The structure is complex, the thread surface requirements are high, and there are steps, grooves, etc., which are easy to deform during processing.
 

2) Anchor rod Accuracy level

In the national standard GB785-65, the accuracy of conventional trapezoidal threads is divided by medium diameter tolerance. There are five basic parameters of outer diameter d, inner diameter d1, middle diameter d2, spacing t and tooth shape half-angle/2. Since the lead screw must transmit the correct movement, according to the provisions of JB2886-81, the accuracy of the lead screw and pitch is divided into six grades according to the requirements of use: 4, 5, 6, 7, 8 and 9.

The application range of screws with all levels of precision is as follows. Level 4 is currently more advanced and is generally rarely applied; Level 5 is used for precision instruments and coordinate boring machines, thread grinding machines and other confidential machine tools; Level 6 is used for precision instruments, precision machine tools and CNC machine tools; Class 7 for precision thread lathes, gear processing machine tools and CNC machine tools; Level 8 is used for ordinary machine tools such as horizontal lathes and milling machines; Class 9 is used for feed mechanisms for planers, drilling machines and general machine tools.

Generally speaking, precision screws refer to 5, 6, 7 grade screws. Precision screws are available in hardened screws and unquenched screws. The former has good wear resistance and can maintain machining accuracy for a long time, but the processing technology is complex and requires high-precision thread grinding machines and special heat treatment equipment, while the latter only requires precision thread lathes. The accuracy classes of ball screw pair and ball screw are also divided into 6 levels.