Improvement Of Drill Point Geometry For Drilling High Manganese Steel ZGMn13

With the rapid development of railroad, more stringent requirements are involved in the rail infrastructure, among of which the turnouts are the weakest components, while the rail crossings are the key parts. These equipments limit train passing speed, and are one of the critical elements affecting speed improving, at the same time, the structure and machining quality influence stability and security of running. At present, the railroad transportation developments are towards to high speed and heavy load, so most of researchers focus on the subjects related to railroad equipments.After investigation to machining plant, lots of drill point failure problems are discovered in drilling operation, which limit the improvement of productivity and increase the production cost. This thesis analyzes the drilling operation and the drill point manufacturing process, then proposes the improvement measure——To decrease drill force and temperature as the target, redesign chisel edge and main cutting edge. In the course of designing drill point, the mechanical model of chisel edge and main cutting edge are analyzed in detail, and the affecting elements are clarified, so a new plan is determined that is to reduce the chisel edge 3mm, use zero rake angle and grind the outer corner angle. The experiment verifies that drill power is decreased fifteen percent, so the new design is perfect.This thesis also considers the causes that lead to crack of carbide blade in the process of braze welding, so in this experiment the induction brazing is adopted and filling piece is fixed to deduce residual stress, as a result, during grinding and practicing, it is not found that drill failure that is caused by blade crack.In drilling experiment, the effect of the new design is evaluated through measuring drilling power, and the influential regulations to the power from cutting speed and feed rate are analyzed, and then statistical graphs are plotted. The study testifies that, owing to work hardening of high manganese steel ZGMn13, the feed rate can not be chosen too small, otherwise cutter wear will be increased. At last, drilling power regression analysis is performed with multivariate linear analysis, and empirical formula is completed. The significance test confirms that the formula is perfect, that establish solid foundation for the following academic.