Grinding Process Study And Quality Control Techniques For The Machining Of YB-70 Backup Roll

As the manufacturing specification (Width) and machining accuracy of rolled sheet continually increases in the metallurgical industry, it makes the size of rolls in finishing mill group enlarged and brings a high degree of accuracy to machining rolls. For example, in a certain type of finishing mill, the diameter of the backup roll reaches 2500mm, the width of roll surface 4000mm, total length 10000mm, gross weight 200t, precision grade IT4-IT5, surface roughness Ra 0.1-0.2. Domestic roll producers do not have the corresponding production capacity of such huge rolls and so strict precision. These high-grade rolls could only be imported form abroad. It increases the production cost of domestic roll producers and restrict the development of machining techniques of such rolls. In this paper, grinding processing technology and quality control techniques have been studied for the YB-70 steel backup roll of a certain roll producer. The main contents are as follows:(1) The orthogonal design and variance analysis method was applied in the grinding experiment of YB-70 steel to study the influence of five factors. Under the experimental conditions of this paper, the optimal parameter combination to get high dimensional precision is wheel grit size 80#, wheel grinding speed 15m/s, worktable longitudinal velocity 9m/min, worktable transverse velocity 0.8mm/s, grinding depth 2μm, to get low surface roughness wheel grit size 100#, wheel grinding speed 15m/s, worktable longitudinal velocity 6m/min, worktable transverse velocity 0.8mm/s, grinding depth 2μm.(2) Optimization model was built with the minimum time as the object, the requirement of surface roughness and grinding force as constraint conditions, and the parameter ranges of the experiment grinder were also considered. Optimization toolbox in the software of Matlab was applied to solve the model. The result showed that to decrease the grinding time, the longitudinal velocity could be increased. The result got was 16m/min.(3) The surface roughness was analyzed theoretically when the grinding depth was minimal and certain times of sparkless grinding were done. The conclusion was the surface roughness would not change when grinding depth was almost half the height of the surface section curve, after many times of sparkless grinding were done, it would approach the theoretical ultimate surface roughness.(4) Optical straightness detector was used to measure the straightness of the experiment grinder guideway. The straightness in the horizontal plane was f1=1.19μm, in the vertical plane f2=0.78μm. Absolute straightness error in the horizontal plane was separated form the error accumulation curve, an error trend model was built to provide reference for the NC interpolation of the grinding carriage.