Four guide rails installation inclined planes are processed out to the rolling frame of ring axial, install the guide rail on the inclined plane, and the guide surface of controlling of frame front end and rear end is the V type respectively and intersects on the central line is controlled to the frame. Two deflector installation inclined planes are processed out, installation copper deflector on the inclined plane to the rolling slider front end of pushing down of axial. Side -mounting direction panel seat is controlled to the rolling slider rear end that forces down of axial, is the inclined plane around the direction panel seat, and the front bevel at the direction panel seat is installed to the copper deflector. The face that leads about slider front end and rear end is the V type respectively and intersects on the central line is controlled to the slider. The direction panel seat can be controlled through guide plate thereafter in the front and back position that forces down the slider, guide plate's the front bevel and the back cant tie of direction panel seat, and guide plate's back plane top is on forcing down the step of slider. The guide plate bottom surface with push down slider side and have certain clearance, when the guide plate bottom surface be close to push down the slider to the side of the time, just with pushing away before the deflector orientation to reduce the guiding clearance.