The invention relates to a broach and discloses a special-shaped hole broach which comprises a
handle part, a neck part, a transition conical part, a front guide part,
cutting parts and a
tail part. The
handle part, the neck part, the transition conical part, the front guide part, the
cutting parts and the
tail part are sequentially connected into a whole from the
cutting-in end to the cutting-out end. A
scrap containing groove is formed between every two adjacent cutting teeth. The total length from the front end of the
handle part to the
tail end of the tail part is not smaller than 1200 mm, and the outer diameters from the front guide part to the tail part in sequence are sequentially increased; the cutting parts comprise round hole teeth, circular arc teeth, cutting teeth, transition teeth and calibration teeth, wherein the round hole teeth, the circular arc teeth, the cutting teeth, the transition teeth and the calibration teeth are sequentially arranged from front to back and connected into a whole. The number of the teeth of the cutting parts is from 130 to 150. The invention further discloses a
machining process method for the special-shaped hole broach. The broach is large in total length and high in slenderness ratio; the multiple cutting parts different in tooth shape are used for
broaching a special-shaped hole, based on the high-precision ultra-slenderness
machining and thermal treating process, a method for carrying out segmentation gradual
grinding through a locating sleeve and a supporting point is adopted, it is ensured that jump of the
solid broach is from 0.01 mm to 0.02 mm, stress deformation caused by cutter relieving and drooping can be effectively avoided, and therefore the stability of
machining and forming is good.