The abnormal wear of the broach refers to the abnormal rapid wear of the teeth during labor, which has a great impact on the production power and processing cost. Under normal conditions, the broach can generally broach thousands of parts between two sharpening. However, in production, it is sometimes encountered that after sharpening only a few dozen or less workpieces, the cutting edge of the broach is already severely worn. The main causes are the poor hardness of the teeth, the annealing of the teeth during sharpening, the unevenness of the tooth lift, the influence of the few angles of the teeth, and the missing blades caused by careless operation.
1. The influence of poor tooth hardness: After broach heat treatment, if the tooth hardness is too low (≤60HRC), or there are local soft spots on the tooth, the tooth will wear out quickly.
2. The effect of annealing after the knife tooth sharpening: When the broach is sharpened, the knife is too large or the grinding speed is too fast, so that the hardness of the cutting edge of the knife is reduced due to overheating and annealing, and it will wear quickly during the broaching process.
3. The influence of uneven tooth lift: When the size of the tooth lift is uneven, the tool tooth with a large tooth lift will increase the wear due to the heavier load during cutting.
4. The influence of the cutting edge angle: When broaching tough and soft materials, a large rake angle should be used to make the cutting edge sharp. When pulling the spline, because the tooth height is large, the metal material needs to recover elastic deformation after being cut. If the side relief angle is too small, the machined surface will be tightly pressed on the side of the cutter tooth, resulting in a big conflict. The two sides of the teeth will squeeze the processing surface of the two sides of the spline, or scratch the groove, and the broach teeth are also easily worn. In actual work, you should carefully observe the conflict marks on the side of the blade to determine whether the side clearance angle is appropriate. If the relief angle is too small, serious conflicts will occur between the machined surface and the flank surface, which will cause the teeth to wear quickly. If the relief angle is too large, the strength of the teeth will be reduced, which will accelerate the wear.
5. Careless operation and missing cutting edge: Because of the careless operation during the upper and lower knife and transfer process, the broach teeth collide with the machine tool or other hard objects, which makes the cutting edge blunt after the cutting edge, which is particularly easy in broaching. Wear. For the above reasons, adopting corresponding methods in broach planning, production, process preparation and operation can make the blade wear normal.