Screw rod pre-tensioning device

The invention discloses a screw rod pre-tensioning device. The screw rod pre-tensioning device comprises a machine tool body; the right end of the machine tool body is internally provided with a motorframe; the inner side of the left end of the motor frame is provided with a rear bearing sleeve gland, and the outer side of the left end of the motor frame is connected with a rear bearing sleeve ina clamped mode; pre-tensioning flanges are composed of two semi-ring flanges; a pre-tensioning end bearing sleeve is internally provided with a bearing distance sleeve, the outer side of the bearingdistance sleeve is continuously provided with two bearings, and the outer sides of the bearings on the outer side of the bearing distance sleeve are each provided with a precision nut; a pre-tensioning end bearing sleeve gland is fixed to the outer end of the pre-tensioning end bearing sleeve; the left end of a screw rod is in threaded connection with the precision nut located on the left side through an external thread; an