Multifunctional mistake-proof fixture for piston finish machining

The invention provides a multifunctional mistake-proof fixture for piston finish machining. The multifunctional mistake-proof fixture comprises an upper base and a lower base, the two of which are stacked up and down into a step cylinder; at least three top surface air outlets for detecting whether a piston is mounted are formed at the outer edge of the top surface of the upper base, while bottom surface air inlets for introducing compressed air are formed in the bottom surface of the lower base; air ducts for correspondingly communicating the top surface air outlets with the bottom surface air inlets are formed in the upper base and the lower base; pressure gauges for detecting the pressures in the air ducts are connected to the bottom surface air inlets; side surface air outlets for piston detection are formed in the circumferential side edge of the upper base in positions corresponding to the top surface air outlets, and the side surface air outlets are communicated with the air ducts. The air holes are additionally formed in the circumferential side surface of the upper base of the multifunctional mistake-proof fixture for piston finish machining to effectively prevent outflow of products having abnormal piston inner diameter dimension; as a result, the product quality stability is improved; 100% monitoring of online devices can be realized, manual measurement by the personnel is not needed, and consequently, the labor intensity of the personnel is reduced and the operability is improved.