钻头的前角和后角在半径的每一点上都在改变着,愈近中心,前角愈小,甚至是负前角。由图1可知,从r=1.25毫米起,前角都是负值。负前角将大大地增加轴向力,它将不是切削,而是刮削,因之对于钻头的修磨就非常必要。正确的修磨不但可以提高劳动生产率,并且可以延长刀具寿命。现在介绍两种新的修磨方法,这是根据我车间老钻工郑淑仁在学习苏联“机械制造快报”所介绍的方法后经过实际使用情况编写而成的。一、交错修磨法如图2所示,把图中的点线部份修磨去,使钻头横刃 The rake and relief angles of the drill bit are changing at each point of the radius, the closer the center, the smaller the rake angle and even the negative rake angle. As can be seen from Figure 1, from r = 1.25 mm, the rake angles are negative. Negative rake will greatly increase the axial force, it will not be cutting, but scraping, it is necessary for grinding bit. Correct grinding not only increases labor productivity, but also extends tool life. Now introduce two new grinding method, which is based on my workshop engineer Zheng Shu Ren learning the Soviet Union, “Machinery Manufacturing Letters,” the method introduced by the actual use of the situation prepared. First, staggered grinding method shown in Figure 2, the dotted line part of the grinding to grinding, the drill chisel