Self-centering clamping oil cylinder structure

The invention discloses a self-centering clamping oil cylinder structure. The self-centering clamping oil cylinder structure comprises a piston rod, a flange cover, a piston cylinder sleeve, and an oil cylinder support fixedly connected with a numerical control rotary table base; the flange cover is fixed at the upper end of the oil cylinder support; the piston cylinder sleeve is mounted in the oil cylinder support; the piston rod penetrates through the flange cover, and can be mounted in the piston cylinder sleeve in the manner of moving up and down; the structure further comprises an upper pressing plate and a lower pressing plate; the piston rod comprises an upper piston rod body and a lower piston rod body, and the upper piston rod body and the lower piston rod body are sleeved together through the cooperation of a hole and a shaft; a butterfly spring is mounted between the upper piston rod body and the lower piston rod body; the upper pressing plate is fixed on the upper piston rod body, while the lower pressing plate is fixed on the lower piston rod body; oil cavities of a sealed structure are arranged on the upper and lower sides of the butterfly spring; the oil cavities of the sealed structure are communicated with pipe joints. The self-centering clamping oil cylinder structure is capable of increasing and decreasing clamping force anytime by adjusting an oil pressure, and therefore, the working reliability and the production efficiency of a rotary table are obviously improved.