The Application of the Uncorrected Tool with a Negative Rake Angle for Tapered Thread Turning

Abstract

Based on geometric modeling and FEM, it is developed a technique for choosing the values of geometrical parameters of a threaded turning tool (rake angle, clearance angle, inclination angle of the cutting edge). This technique depends on the allowable values of kinematic rake and clearance angles at different points of the cutting edge and reliability characteristics of the threaded connection—fatigue strength and contact pressure in the thread. Using this technique, it is reasonable to use tools with an uncorrected profile and a negative value of the static rake angle at the nose point −10° for turning the pin thread of the tubing with a diameter of 114 mm, which is made of difficult-to-machine steel. The calculated values of the kinematic rake angles (−4.4°…−5.5°) indicate improved cutting conditions. Fatigue strength of the threaded connection almost does not change, but in order to avoid gaps in the connection, the coupling thread must be made by taking into account the difference in the flank angles of the pin and coupling.