Processing influence of Fried Dough Twists drill

(1) The diameter of the Fried Dough Twists drill is limited by the hole diameter. The spiral groove makes the drill core thinner and the drill bit has low rigidity; With only two edges guiding, the axis of the hole is prone to deviation; The horizontal blade makes it difficult to center, increases axial resistance, and makes it easy for the drill bit to swing. Therefore, the positional error of drilling holes is relatively large.

(2) The rake face and back face of the Fried Dough Twists drill are curved surfaces. The rake angle and back angle of each point along the main cutting edge are different, and the front angle of the transverse edge is -55 °. Poor cutting conditions; The distribution of cutting speed along the cutting edge is unreasonable, and the cutting speed of the tool tip with the lowest strength is the highest, resulting in severe wear. Therefore, the precision of the processed holes is low.

(3) The main cutting edge of the drill bit is fully engaged in cutting, and the cutting speed at each point on the edge is not equal, which can easily form spiral chips and make chip removal difficult. Therefore, the chips and the hole wall are squeezed and rubbed, often scratching the hole wall, and the surface roughness after processing is very low