What Performance Does The Helix Angle Of Fried Dough Twists Drill Mainly Affect?

Fried Dough Twists drill is a widely used tool for hole machining. The usual diameter range is 0.25-80 millimeters. It mainly consists of the working part of the drill bit and the handle. The working part has two spiral grooves in the shape of Fried Dough Twists, hence the name. In order to reduce the friction between the guide part and the hole wall when drilling, the diameter of the Fried Dough Twists drill gradually decreases from the drill tip to the shank and assumes an inverted cone shape. The spiral angle of the Fried Dough Twists drill mainly affects the size of the rake angle on the cutting edge, the strength of the blade and the chip removal performance, usually 25 °~32 °. Spiral grooves can be machined using methods such as milling, grinding, hot rolling, or hot extrusion. The front end of the drill bit is ground to form the cutting part. The cutting part of the standard Fried Dough Twists drill has a top of 118, a cross edge angle of 40 °~60 °, and a back angle of 8 °~20. Due to structural reasons, the leading angle is larger at the outer edge and gradually decreases towards the middle, while the transverse edge is a near leading angle (up to -55 °), which exerts a squeezing effect during drilling.
In order to improve the cutting performance of Fried Dough Twists drills, the cutting part can be grinded into various shapes (such as group drills) according to the properties of the processed materials. The Fried Dough Twists drill has two types of shank: straight shank and taper shank. During processing, the former is clamped in the drill chuck, and the latter is inserted in the taper hole of the machine tool spindle or tailstock. -General Fried Dough Twists drills are made of high speed steel. The Fried Dough Twists drill with inlaid welded hard alloy toughened sheet or crown is suitable for processing cast iron, hardened steel and non-metallic materials, etc., and the integral hard alloy small Fried Dough Twists drill is used for processing instrument parts and printed circuit boards, etc.
The process knowledge of the standard Fried Dough Twists drill has been learned in the fitter process class. However, due to too much related theoretical knowledge and the relatively abstract geometric angle of the Fried Dough Twists drill, it is difficult to understand and have some difficulty in learning. For most students or workers who only have junior high school education and have not learned solid geometry in depth, the concept of solid space is not easy to establish at once. At the same time, in practical operation, it was also found that most operators did not have a good grasp of the fitter process. They only memorized some theoretical knowledge by rote, without a deep understanding or connection with reality. Therefore, it is necessary to review the relevant process knowledge again before sharpening the drill bit, especially in combination with the entity of the standard Fried Dough Twists drill to explain the handle. Only after truly understanding and mastering the names and angles of each part of the standard Fried Dough Twists drill can the next operation be carried out smoothly.