Design And Experimental Research Of A Multi-faced Numerical Control Grinding And Polishing Machine

The purpose of this paper is to develop a multi-faceted NC grinding and polishing machine, the machine can complete grinding and polishing all faces of the work-piece except the lower face in a fixture, greatly improved the processing efficiency and precision. Firstly, made an investigation into the development of domestic and foreign stone processing machine, then combine with the actual needs of local Xiamen, designed the mechanical structure of the NC grinding and polishing machine; Secondly, built the hardware system and software system with CMOS camera as the core of machine vision; Then, established a grinding and polishing machine control hardware system based on the SMC6480 controller and established the software system of the machine; Finally, XL-80 laser interferometer is used to detect the positioning accuracy and repeat positioning accuracy of the grinding machine and made use of three-coordinate measuring instrument to study the material removal effects of different process parameters on the work-piece.The major work of this paper is as follows:(1) Made an investigation of the development of domestic and foreign stone processing machine, then combine with the actual needs of local Xiamen, designed the mechanical structure of the CNC grinding and polishing machine. The machine is gantry structure. The grinding module include electric grinding spindles and spindle feed cylinder, is fitted on each beams and columns, using cylinder as spindle driver can achieve soft contact of the work-piece and the grinding spindle in order to protect the spindle. The module can be driven by a stepping motor along the linear guide rails to complete grinding, the guide rails, ball screw drives, stepper motor and other majorcomponents were been selected based on the forces of each axis. Then made static and dynamic analysis of this machine using ANSYS and the results showed the structure stiffness can meet requirements. As the stone processing will generate a lot of dust,the grinding head and work-piece are enclosed in one space, this method can not only protect the guide rails, bearings and other transmission parts but also prevent grinding waste splash, achieved good waterproof and dustproof effect.(2) Machine vision was used to extract edge contour of the work-piece and the contour data was applied into NC machining. This paper selected Mindvisionn’s DLC-300 CMOS camera and YX-0612 industrial lens as the image acquisition unit to set up machine vision hardware platform. Camera was calibrated using MATLAB to get the inside and outside the parameters. The steps of machine vision is: First the image is grayed and then smoothed, filtered and extracted the edge, and then the mathematical morphology method was used to extract a smooth edges, the four corners of edges in the image coordinates was set as the starting and ending point of NC machining.(3) Designed the hardware and software systems of the controlling system for this grinding and polishing machine. This paper used open-loop control. The self-made controlling box integrated the controllers, actuators, frequency converter,serial-to-analog output module, electromagnetic valve and other control units. The SMC6480 controller was used to control the stepper motor driver and electromagnetic valve, the serial-to-analog output modules was used for frequency converter to control the spindle speed. MFC was used to designed NC software system, the software is divided into manual mode and automatic operation mode, the manual operation mode is suitable for machine debugging, automatic operation mode is suitable for automatic processing. Automatic operation mode can be divided into single-sided, double-sided and three-sided grinding depending on processing needs.(4)XL-80 laser interferometer is used to detect the positioning accuracy and repeat positioning accuracy of the grinding machine. The mechanism of material removal was well understood, then combine with the actual experience in processing with the grinding and polishing machine itself, the SPECTRUM CARL ZEISS coordinate measuring instrument was used to study the material removal effect of discmesh, spindle speed, grinding pressure and other parameters.