DRILLING HOLES WITH A CUTTING TOOL WITHOUT A TRANSVERSE EDGE AND THEIR EFFECT ON THE ACCURACY OF THE MACHINED HOLE

Abstract

To drill high-strength and heat-resistant steels and alloys, it is necessary to create such a geometry for the cutting part of a double-flute drill that, while maintaining axial stability and a sufficiently strong cutting wedge, would ensure a uniform, vibration-free cutting process even if chip formation occurs in some areas of the cutting edges in the presence of growths. For chip formation conditions during drilling, the appearance of build-up and build-up is possible near the transverse cutting edge, where cutting speeds are low. Most researchers believe that the main reason for the decrease in the performance of drills, including those equipped with inserts made of hard alloys, is the large negative values of the rake angles near the transverse cutting blade. Therefore, the improvement of the design of spiral drills is carried out mainly through different types of sharpening of the transverse blade and special sharpening of the cutting part.   In general, the size of the breakdown of the hole after applying the developed drill is less than that of the spiral. This difference increases with increasing feed and reaches 2 times when reaching a feed of 0.17 mm / rev. The article considers the issues of ensuring the accuracy of holes machined with a special drill and presents the results of studies with a standard drill.