The utility model relates to the technical field of
diesel engine plunger and
barrel assembly machining equipment, in particular to a positioning tool for
diesel engine plunger and
barrel assembly polishing. According to the technical scheme, the positioning device comprises a supporting plate, positioning boxes are connected to one side of the supporting plate in a sliding mode, and the three positioning boxes are arranged on one side of the supporting plate in a circumferential array mode. According to the utility model, the positioning box, the external expansion pushing block, the internal contraction pushing block, the
extrusion block, the telescopic screw rod, the pushing plate and the fixing sheet are matched with one another. According to the device, the mode that a telescopic screw rod controls an
extrusion block to move is adopted, the
extrusion block extrudes an external expansion pushing block or an internal contraction pushing block, so that different pushing plates are controlled to drive a fixing piece to protrude out of the interior of a positioning box, and then the fixing piece is fixed inside or outside a
diesel engine plunger and
barrel assembly; the problem that when the interior or the exterior of the diesel engine plunger and barrel assembly is fixed, a corresponding clamp needs to be selected, and consequently the working efficiency is low is solved, and the working efficiency when the diesel engine plunger and barrel assembly is polished is improved.