Upper disc system of high-precision polishing machine

The invention relates to polishing equipment, in particular to an upper disc system of a high-precision polishing machine, which comprises a motor arranged on a support of the polishing machine, an air cylinder and an upper disc which is driven by the motor to rotate through a middle shaft and can be used for polishing, and the air cylinder is hollow and drives the upper disc to move up and down. The lower end of the middle shaft vertically penetrates through a cavity of the air cylinder to be connected with the upper disc, the outer side of the upper end of the middle shaft is sleeved with a sliding sleeve installed on the support, the sliding sleeve is driven by the motor to rotate, the rotating sliding sleeve drives the middle shaft to rotate, the middle shaft drives the upper disc to rotate, and when the air cylinder drives the upper disc to move up and down, the sliding sleeve is driven by the motor to rotate. And the middle shaft slides up and down relative to the sliding sleeve. The rotating middle sha