( 1. Xi’an Vocational and Technical Institute, Xi’an 710077; 2. School of Mechanical and Precise Instrument, Xi’an University of Technology, Xi’an 710048; 3.School of Mechanical Engineering Instrument, Heilongjiang niversity of Technology and Science, Harbin 150027; 4.School of Printing and Packaging Engineering, Xi’an University of Technology, Xi’an 710048 )