Positioning device for metal product machining

According to the positioning device for metal product machining, four sliding grooves are formed in the surface of a workbench in a circumferential array mode with the center point as the circle center, and connecting lines among the four sliding grooves are in a cross shape; the sliding block is slidably installed in the sliding groove. By the adoption of the technical scheme, the table top wrapped with the metal enclosure is placed on the workbench, the sliding blocks in the sliding grooves are driven by the synchronous driving mechanism to synchronously move towards the center point of the surface of the workbench, and the metal enclosure is clamped and positioned through the combined clamping plates on the sliding blocks; the first clamping plate and the second clamping plate are installed in a combined mode, the metal enclosure is clamped and positioned through the plane clamping face of the second clamping plate, when the metal enclosure is round, the second clamping plate is detached from the first cla