BASICS OF AUTOMATION OF PROFILING OF HIGH-EFFICIENT INSERTS OF THE TOOL FOR THREAD MACHINING

Many modern threaded joints especially in the oil and gas industry, must satisfy high requirements for steel mechanical properties of which they are made. To ensure efficient threading of such hard-to-machine materials (ultimate strength is more than 1250 MPa), it is necessary to use carbide cutting inserts with the negative rake angle at its corner. However, modern manufacturers of such inserts make them only with a zero value of the rake angle. This is due to the difficulty of profiling of the insert cutting edge. This article proposes the basics of such inserts automatic profiling which is based on the algorithm developed by the authors. It includes two corrective calculations of the insert cutting edge profile, namely: the radial displacement of the corner and the tangential displacement of the area forming the crest of the thread. As a result, the computer application with the input parameter of the rake angle and output parameter of the upgraded profile of the insert cutting edge is received.

New possibilities of worm thread machining and practice of implementation

Thread grinding is the traditional operation of final machining for worms and other critical threads. However, similar to other types of tooth grinding, this type of machining is expensive; it requires application of high cost equipment and needs valuable workers. In many practical cases, its alternative can be the application of edge machining, especially as the possibilities of controlling the corresponding advanced machine-tools and their accuracy have been increased significantly. This paper describes the experience of implementation of edge machining of worm threads within a low-series production of spiroid and worm gearboxes for pipeline valves gained at the Institute of Mechanics named after prof. V.I. Goldfarb of Kalashnikov Izhevsk State Technical University and at the Small Innovative Enterprise “Mechanik”. Schemes of thread machining by straight and radial parts of a single cutter and by a face cutter head are considered. The technique is implemented, and it provides the reduction of labor intensity and prime cost of both the preliminary and final machining of worms, including heat-strengthened ones; and it also results in the correctly localized contact in worm and spiroid gears.

Trapezoidal Thread Processing Method Based on Surface Discretization

In order to realize special trapezoidal thread production more quickly and simply, a new processing method is presented. Based on the shape analysis of the spiral curve, spiral surface discrete algorithm is discussed. Spiral surface is discretized in to numerous tiny straight segments, and consequently the trapezoidal thread machining can be accomplished by just using G01. Simulation and experiment results show that this processing method is feasible and with high production efficiency.