Study On BTA Deep Hole Drilling Chip-breaking Mechanism And Groove Design

Low pressure heater of steam turbine is an important part of nuclear power equipment, the deep hole processing of the heater tube plate is difficult. Because of high production efficiency and processing quality, BTA(Boring and Trepanning Association)deep hole drilling is widely used in low pressure heater. However, due to the high toughness of the material to be processed, chip breaking and chip removal are difficult. To solve the above problems, this paper proposes a experiment method about turning replace drilling,and mainly study on the aspect of deep drilling model, the relation between cutting force and cutting edge under different angles.Firstly, aim at the working environment of BTA deep hole drilling, establish a test model of turning replace drilling. Do not change the dimensions and angles of the outer edge, the center edge, and the center edge and ensures that the position of each edge is unchanged relative to the deep hole drill, By cutting the end face of workpiece to simulate the machining process of each cutting edge.Secondly, research on drilling force: the orthogonal experiment were designed based on angle of deep hole drilling for the outer edge, the middle and the center edge blade, analysis of the influence of different angles on cutting force, and get the optimal combination of each angle of cutting edge by range analysis.Thirdly, the research object is the chip breaking effect: The chip curl radius is an important index of the cutting chip bending, analysis of the morphology of each cutting edge chip, through range analysis analyzes the different edges of each cutting edge inclination angle, relief angle and declination angle the influence of the chip curl radius, the results shows that changes in each angle limited impact on the curling radius of chips.The last, According to the drilling center edge exists difficult problem of chip breaking, using finite element analysis, establishment of the center edge drilling model, analysis of the cutting force and cutting heat and chip morphology under different parameters with groove width(2n, and obtains the influence law of the optimum (2n parameters on chip breaking.