Research On Online Vision Measurement Technology For Large Spherical Milling Cutter's Contour Size

Large size spherical milling cutter is widely used in the area of free-form surface machining.The accuracy of its contour measurement directly affects the accuracy of machining.The visual measurement method has the advantages of non contact,high precision and wide range of application.The visual measurement of the tool is mainly concentrated on the small and medium size tool,and the research on large size tool measurement is less.In this paper,aiming at the relative blank in the field of visual measurement of large ball end milling cutter,with the ball knife with diameter of 20 mm and 30 mm as the research object,the design and development of the system,the system error compensation and the improvement of the image stitching precision are carried out.The specific contents are as follows:In view of the outline dimension measurement of the large spherical milling cutter head,a set of on-line measurement system is designed and developed.The system has the function of collecting the image of the tool sequence,auto focusing and image processing,so that the complete outline image of the large ball knife is obtained.Take and measure the radius.It does not need to unload the tool,so it does not need to find the positioning datum again,and feedback the result to the machine tool to adjust the machining parameters of the machine tool,so as to improve the machining precision and speed.In view of the positioning error of the grating ruler in the system,a method of measuring the error of the image method is used.This method establishes the relationship between the positioning error of the system and the measuring value of the grating ruler,so as to achieve the purpose of compensating the positioning accuracy error of the compensation system,and the positioning accuracy of the grating ruler is increased by 30% after compensation.In view of the traditional sequence image stitching method,it is applied to the problem of splicing step in this system,and an improved algorithm is used to match the error of thesystem with the system error to eliminate the vertical direction deviation of the image.Finally,the experimental results show that the stitching ladder of the image is disappearing.When measuring the diameter 20 mm and 30 mm,the measurement error of the radius is less than 0.09%.At the same time,the shape of the tool is visualized in a graphic way,and the shape variables of each part of the tool are directly reflected.