According to the former, the important role of the paint sand mill is to paint the surface geometry of the sand mill itself, accurately transferred to the workpiece to be investigated. Based on this point, if the surface of the paint sand mill is the ideal plane, then the surface of the workpiece should be high precision plane. But in the grinding practice ideal plane is very little, the research of the workpiece surface is error. This is mainly because:br />
(1)When grinding, the relative motion between the workpiece and the paint grinder is changing in the direction of the grinding machine (for the precision grinding, the paint sand mill is stationary). In the research in motion, because by starting torque, torsional torque and inertia force and other complex by force, contributed to the grinding process in mobile instability, caused by the edge of work force, is research out of many, is the result, despite the use of high precision oil paint sand mill, the grinding workpiece surface is still error, and often is convex. In order to eliminate the convex shape of the workpiece caused by the movement of the workpiece, the convex surface of the paint grinder can be used to compensate the workpiece.
Mobile stable caused by many factors, for example, not in the workpiece is research surface size and height ratio to determine the speed and direction of motion, when the spoke plate support dynamic grinding workpiece, radials didn't put in the middle position of the workpiece, workpiece is forcibly by force or focus on inequality.
(2In the grinding process, the surface of the paint grinding machine is easy to be formed because of the large abrasion ratio in the middle of the paint sand mill. And practice shows that the concave surface of the paint sand mill, it is not out of the high precision of the workpiece surface. To this end, the need to use the convex surface of the paint grinder to solve the uneven wear caused by the quality of the problem, so that it also played a role in prolonging the life of the paint sand mill, improve production efficiency.
(3)For hand grinding, because of the double focus position more concentrated in the workpiece at both ends, this will produce the workpiece heat deformation, the problem of uneven. Even using high precision paint sand mill to grind, due to the two ends of the work piece heat deformation, ends up being research out of many, isothermal, research workpiece surface is convex. So when grinding, should choose the convex shape of the paint sand mill, in order to maximize the impact caused by the thermal deformation.
(4)In the deposited sand polishing towel. Due to the coating paste, grinding agent in the workpiece and paint sand mill flow, resulting in cutting action. As a result, the workpiece front elevation (refers to the direction of movement). As a result, the end off the edge off angle phenomenon. Similarly, the need for the use of convex paint sand mill to compensate.
It can be seen that, in order to make the workpiece to obtain a more ideal plane, the surface of the grinding plate should be a uniform convex surface. The convex shape of the paint sand mill is much better, but also according to the specific situation and experience to determine the grinding. Generally speaking, the faster the grinding speed is, the higher the height of the workpiece is, the larger the heat distortion of the workpiece is, the higher the convex shape of the paint sand mill. For example, when the mechanical polishing is the most common, the paint sanding machine which often uses the surface convex and a light interference belt is used for grinding, and the angle of the manual polishing is used, and the sand grinding machine with three light interference bands is used.