How should the rotation speed of the main center of the quenching machine tool be selected?

The selection of the rotation speed when the quenched workpiece is heated. From the uniformity of the heating of the workpiece, the faster the rotation speed, the less the influence of temperature unevenness caused by the uneven gap between the inductor and the workpiece. Early quenching machine tools generally set the speed range of 60-300/min. Some machine tools have a stepless speed change, and some machine tools use a stepless speed change, which the user can choose at will. However, some machine tools have extremely low speed due to specific conditions. For example, the crankshaft journal rotary hardening machine, the main journal speed is usually 60r/min, while the connecting rod journal speed is 30r/min. This is because the connecting rod neck rotates on the hardening machine through a swing mechanism (four-connected rod structure). If the rotation speed is too fast, the half-ring sensor cannot stably move across the journal, so it can only rotate at a low speed of 30r/min. This speed is inappropriate for journal heating. The main journal uses 60r/ Min is the reason that the design can be simple due to the use of a two-speed motor.

There is an argument that the selection of speed should be considered in the heating cycle of the workpiece. The workpiece should be rotated no less than 10 times in a heating cycle to ensure uniform temperature on the circumference of the workpiece. According to this calculation, the induction heating time of the general workpiece is usually between 5-10s. If it is 5s to 10 revolutions, it is 120r/min. If it is 10s to 10 revolutions, the speed is 60r/min.

With the development of induction heating speed, for synchronous dual-frequency heating gears, the heating period of the gears has been shortened to 0.1-0.2s. Therefore, the requirements for the speed of the workpiece are constantly increasing, and the maximum speed of the spindle of some quenching machine tools has reached 1600 people/min. At present, it is rare that the speed of the quenching machine tool reaches 600r/min. In addition, the rotation speed of the workpiece is also closely related to the cooling. For gears and spline shafts, quenching and cooling often use a liquid spray method. The rotation of the workpiece is too fast, and the quenching liquid is insufficient to cool one side of the tooth. Therefore, the speed of the quenching machine tool is still 600r/min or 300r/min as the upper limit. In addition, it is necessary to develop mechanical or electrical components that can reduce the speed of the workpiece in time after the heating is completed, so that the workpiece can rotate quickly to achieve uniform heating, but also rotate slowly to achieve the requirements of uniform cooling of gear workpieces.