How to design fixtures and positioning components in precision parts processing

In precision parts processing, the specific material for clamping is generally gray cast iron, which is in the form of angle iron. The main positioning surface of the workpiece is vertically set, and a through hole for installing positioning pin 8 is set on the front; Set the small convex block planes for installing positioning support blocks 5 and 9 according to the dimensions at the outer circle position of the workpiece ø 110mm; Set up a step hole in the lower right corner for installing the spiral hook type pressure plate 12; Set the tool alignment block 3 above the positioning pin hole. The vertical part of the fixture is increased in stiffness by the ribs on both sides. The fixture base is equipped with a keyway for installing the fixture positioning key and a semi open straight groove for threading and tightening the fixture screws.

In precision parts processing, the design of positioning components usually uses standard support plates for planar positioning, which are fixed on clamp 1 with internal hexagonal screws; Select positioning pin 8 for internal hole positioning. The taper guide section at the front end of the positioning pin facilitates workpiece clamping. The shaft is pre equipped with a tool groove, and the 6mm flat key 6 is fastened to the keyway on the positioning pin 8 by two M4 screws 7 to prevent the flat key from falling off during workpiece clamping.

Make the fixture between the knife slot and keyway 125 °, and use a transitional fit between the positioning pin and the fixture. After aligning and oblique machining the positioning position, fix the positioning pin 8 on the fixture with M5 screws 18.