Joint Grinding Machine is a most precise, automatic, copper surface of cylinder processing equipment made by MDC company of Switzerland whose feature is precise mechanical displacement of moving parts, the hydraulic pressure suspended main shaft has little friction and volls smoothly. At the same time, itself has a precise set of accurate gas-moving measure apparatus which does comprehensive survey of the size of cylinder to lessen the precision error to the lowest point. The precision rate can reach: cone rate ±3um, ellipse rate±3um, crudity rate of surface 0.2-0.3um, wave 0.8um, locatint rate±3um.