Surface grinders are machine tools that use abrasive tools to grind the surface of workpieces. Most surface grinders use high-speed rotating grinding wheels for grinding, and a few use oil stones, abrasive belts, and other abrasive tools and free abrasives for processing. With the increase in the number of high-precision, high-hardness mechanical parts.
   As well as the development of fine casting and fine forging processes, the performance, types and output of grinding machines are constantly improving and increasing. The outer circle of the front and rear bearings of the surface grinder grinding head is tapered, and there are three equally divided flanges in contact with the inner tapered hole of the bearing seat.

After analysis, it is found that there are longitudinal cracks on the local surface of the journal of the grinding wheel shaft in the surface grinder, and there are no obvious defects in the front and rear bearings, and the amount of wear is not large. There are superficial longitudinal cracks locally in the journal. The outer cone flanges of the front and rear bearings are in good contact with the bearing seat hole, and the inner hole of the bearing has no obvious damage. Therefore, it is believed that the main reason for the inoperability of the grinding head is that the geometric accuracy of the front and rear bearings changes, and the shape and size of the three oil wedges are not different.

   For this problem, we adopt the method of scraping and grinding separation to stop maintenance: install the front and rear bearings to the working position, and grind a cylindrical mandrel with a length of 400mm according to the bearing hole. Apply a thin layer of red dan oil on the mandrel, insert the mandrel into the bearing, adjust the tightness level of the front and rear bearings properly, rotate the mandrel, and pull out the mandrel to lightly scratch the points.