Application of medium frequency induction heating power supply in alloy cast iron camshaft quenching process

The alloy cast iron camshaft quenching device consists of a medium frequency induction heating power supply of 10kHz and 200kW, a quenching machine tool, a softened water circulation device and an electric control cabinet. The camshaft processed is a four-cylinder 2.0L gasoline engine camshaft made of Ni-Cr-Mo alloy cast iron, with a maximum The shaft diameter is 50.8mm and the total length is 434mm.

(1) Structure of quenching machine tool

The quenching machine tool consists of a bed, V-shaped bracket, movable rod, sliding table with tip, quenching transformer sensor group, capacitor and quenching tank. The mechanical action is controlled by hydraulic pressure. The V-shaped bracket holds the workpiece up and down to the position, and then the movable rod cooperates with the action. The two tips on the sliding table clamp the camshaft and move it laterally to move the camshaft into or out of the sensor. The main spindle box at the left end of the machine tool is driven by a hydraulic motor to rotate the camshaft, and the speed can be continuously adjusted within a certain range. There is a copper plate grounding ring on the left side of the sensor. If the camshaft is not clamped correctly on the tip, it will first hit the grounding ring when moving laterally, generating a signal and stopping the action.

The quenching transformer is a variable turns ratio medium frequency transformer with 10 to 22 turns on the primary side divided into 13 gears and 6 turns on the secondary side. The medium frequency induction heating power supply inductor is a multi-circle series connection, with 9 inductors located on a center line, including 8 heating cams. The sensor is double-turn, and the gap between the cam tip and the inner diameter of the effective ring is 4~5mm. The sensor base has an elliptical hole so that the axial position of the sensor relative to the cam can be adjusted. The camshaft inductors are connected in series, which avoids the shortcomings of short conductive paths in the middle and long conductive paths at both ends when multiple inductors are connected in parallel. When using the series inductor method, if the temperature of the middle cam is too high, it can also be adjusted by increasing the gap.

(2)Quenching tank and conveyor chain

The quenching tank capacity is 1.5m³, the polymer quenching cooling medium UconA or 251 is selected, its mass fraction is 10%, and the operating temperature is 3~50℃. The quenching tank is equipped with a 6KW tubular electric heater to adjust the temperature of the quenching cooling medium. There is a heat exchanger and a water pump next to the quenching tank. The water pump sends the quenching cooling medium with increased temperature into the heat exchanger, and exchanges heat with the cooling water in the heat exchanger for cooling. The temperature, flow and other controls of this system are the same as those of the general quenching cooling medium cooling system and will not be described in detail.

(3) Infrared thermometer

The infrared thermometer monitors the camshaft heating temperature. It is installed 0.5m away from the center of the sensor. The lens on the sensor is aimed at the side of a certain cam. If the final heating temperature of a certain camshaft is too low, the infrared temperature measurement The instrument will send out a failure signal, and the rejection operating arm in front of the quenching tank will be raised to prevent the camshaft from entering the quenching tank.

(4)Exhaust device

The upper part of the medium frequency induction heating power sensor and the upper part of the quenching tank conveyor chain lifting the workpiece are equipped with exhaust hoods to maintain a fresh environment near the workstation.

(5) Program controller

The electric control cabinet is equipped with a program controller to control process parameters, etc., and is protected against water shortage, overcurrent, overvoltage, etc. The sensor return pipe of this device is also equipped with a glass device that can visually return water, allowing direct observation of water shortages. This device has high productivity for camshaft quenching.