What is the trick of nc machine drilling?
In mechanical processing, the proportion of drilling procedure to the hole and hole system processing has
been common, but for the processing of small diameter hole there are some practical problems, which is easy to
break because of the small drill bit. It causes great waste and affects machining accuracy, machining quality and
1.Main cause of bit break
Bit diameter is small, strength is not enough, small diameter drill screw Angle is relatively small, not
easy to chip, so small diameter drill is easy to break in the process of using. The cutting speed of drilling holes is high, the cutting temperature generated by the bit is high and it is difficult to dissipate heat, especially the contact temperature between the bit and the workpiece is higher, which aggravates the wear of the bit. In the process of drilling, manual feeding is generally used, the feeding force is not easy to grasp evenly, often a little careless will make the drill bit damage. Because the rigidity of the small diameter drill is poor, easy to damage the bending, resulting in the borehole tilt.
(1) change of bit geometric Angle The change of bit geometry Angle is the main cause of bit fracture, among which the change of drill edge top Angle has a great influence. The so-called drill edge top Angle is the included Angle between the two main cutting edges of the bit. The top Angle of the drill edge of a standard twist drill is 118? When the top Angle of the drill edge is greater than 118? When the two main cutting edges are concave curves, when the top Angle of the drill edge is less than 118? When, the two main cutting edges are convex curves, only when the top Angle of the drill edge is equal to 118? When the two main cutting edges are straight. But the smaller the diameter of the bit, the more difficult it is to control the top Angle of the drill edge, resulting in an imbalance in drilling force and torque that forces the bit to go off course while drilling, causing the bit to break. (2) changes in drilling axial force and feed When drilling on the lathe, the feed is too small, generally only 0.001mm per turn. It is completely
controlled by the operator’s hand, so it is difficult to guarantee the uniformity of feed and axial force, a
little careless will lead to a sharp change in the axial force and feed, and make the drill bit broken. So the smaller the diameter of the drill, the larger the feed, the bit will break.
(3) influence of operators and drilling materials During drilling, the concentration and dispersion of the operator's energy are also one of the reasons for the fracture of the drill bit. Secondly, the influence of processing materials is also very big, especially the materials with strong toughness, chip removal is difficult and easy to block, but also easy to break the drill bit.