Abstract
Accuracy of grinding wheel profile that is generated by form grinding theory and formed by grinding wheel dresser is a crucial factor affecting profile accuracy of screw rotors. A correction method for screw rotor profile error based on parameter adjustment for grinding wheel dresser such as diameter and distance of diamond rollers is proposed. Influence of diameter and distance of diamond rollers on grinding wheel profile and screw rotor profile based on theory of segmented dressing method is analyzed, and the adjustment method for parameters of grinding wheel dresser is presented. The results of the analysis provide a theoretical basis for error correction in screw rotor grinding. Grinding experiments for female rotor were performed due to the character that the female rotor has smooth bottom profile where the change of profile error is easy to observe. The experimental results show that the height difference between the long and short sides of rotor profile at the bottom of the rotor is significantly reduced from 0.22 mm to 0.034 mm by adjusting diameter of diamond rollers, and the distance between the long and short sides of the actual rotor profile is almost consistent with the theoretical one by measuring the distance again and adjusting its value in the computer numerical control system. These results verify the correctness of the correction method.
Highlights
As core parts of screw machine, screw rotors are widely used in compressors, industrial pumps, refrigerators, and other equipment
The goal of the article is to propose a correction method of screw rotor profile error based on parameter adjustment for grinding wheel dresser
By analyzing the influence mechanism of parameter errors of grinding wheel dresser on the profile of screw rotor with segmented grinding method, it is found that the larger the distance between diamond roller and V-axis in computer numerical control (CNC) system, the narrower the distance between the long and the short sides of screw profile, and the reduction of the diameter of diamond roller will cause the height difference between the long and short sides of rotor profile at the bottom of the rotor
Summary
As core parts of screw machine, screw rotors are widely used in compressors, industrial pumps, refrigerators, and other equipment. The accuracy of the screw rotor profile has a great influence on the performance of screw compressor.[1] It requires a precision machining method for screw rotors. Form grinding is the most common processing method for screw rotor. Zhao et al.[2] present a precision grinding method for screw rotors based on a computer numerical control (CNC) grinding wheel dressing. To improve the accuracy of screw rotor profile under form grinding, some researches seek methods to reduce machine tool errors. Shen et al.[3] analyzed the internal and external errors of the machine tool and presented a method of error compensation to reduce the rotor profile error based on the finite sample test. Tian et al.[4] proposed a comprehensive and systematic modeling method for geometric errors of machine tools to separate these error sources that have effect on the pose accuracy of the machine tool
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