DEFORM-AND EXHAUST-CONTROLL OF CHIP IN DRILLING WITH A NEW TYPE TWIST DRILL II

在连续进给条件下，麻花钻钻深孔加工时，为了排屑，需要使钻屑槽和被钻削的孔变形为小直径圆锥螺旋形或螺距等于槽距的长螺距螺旋形。每个切削刃独立地切削工件材料。每个切削刃产生的切屑并不完全统一。第二主切削刃产生的切屑附着在作为主切屑的第一主切削刃产生的切屑上。这是切屑变形和排屑控制的基础。由于第一主切削刃倾角较大，所以锥形螺旋型切屑的螺距较长，在深孔加工中，由排屑槽和钻孔控制其为长螺距型。长螺距螺旋型切屑的切削比小于圆锥螺旋型切屑的切削比。特别是，在外部边缘，它非常小。下 关于我们 在弯矩和切屑与槽和孔之间的摩擦力的作用下，切削区产生压应力。特别是它在外面的边缘很大。这使得在被加工材料塑性好的情况下，剪切角变小，从而产生长螺距螺旋型切屑。第二主切削刃的影响也很大。第2主切削刃前角为4 °的钻头比0 °前角钻头在钻削初期产生长节距螺旋型切屑。在S50 C钻削中，在各种切削条件下，切屑形态向长节距型转变时，前刀面处的切削温度约为400 ℃，在此温度下，其塑性变大。长节距切屑的不稳定产生，使径向切削力产生振动。切屑形态变化与切削力特性之间的关系尚不明确。少

In order to exhaust chip in deep hole drilling with a twist drill under continuous feed, it is necessary that the drill flute and the driffed hole deform it to the smaller diameter conical helix type or to the long pitch helix type chip whose pitch is equal to the flute pitch.A new type twist drill has two cutting edges on each side. Each cutting edge cuts work material independently. The chip generated by each cutting edge are not perfectly unified. The chip by the 2nd main cutting edge is attached to the chip generated by the 1st main cutting, edge which is main chip. This is the basis to the deform and exhaust controll of chip. As the 1st main cutting edge has large oblique angle, so the conical helix type chip has longer pitch, and the flute and the drilled hole controll it to the long pitch type in deep hole drilling. The cutting ratio of the long pitch helix type chip is smaller than that of the conical helix type chip. Especially, at the outside edge it is very small. Under the … More action of the bending moment and the frictional force agaist chip by the flute and the drilled hole, the compressed stress occurs at the cutting region. Especially it is large at the outside edge. This makes the shearing angle small under good plasticity of work material and then the long pitch helix type chip occurs. The effect of 2nd main cutting edge is also large. The drill with the 2nd main cutting edge of 4 degree rake angle produces the long pitch helix type chip at earlier stage in drilling than in case of the 0 degree rake angle drill.The cutting temperature is about 400ﾟC at rake face when the chip form chages to the long pitch type under various cutting conditions in drilling S50C.Its plasticity becomes large at this temperature. So, the chip does not fracture and changes to the long pitch type.Unstable generation of the long pitch type chip makes the radial cutting force vibratory. The relation between change of chip form and the characteristics of cutting force is not clear. Less