Foreign IGBT, MOSFET and SIT solid-state transistor power supply technologies have gradually become mature, and have been commercialized and serialized. At present, there are 1200kW, 50kHz;50 ~ 100 KHZ, 30 ~ 600 kw;300 kw, 80 kHz;Low frequency band has the tendency to replace the thyristor power supply.MOSFET mostly adopts a parallel oscillator circuit, SIT mostly adopts a series resonance circuit, with power up to 1000kW, frequency 200kHz, 400kW, 400kHz.They are ideal substitutes for vacuum tube high frequency power supplies. When the output power is the same as the valve power supply, it can save 35% ~ 40% electricity, 50% installation area, and 40% ~ 50% cooling water. With the development of technology, MOSFET is expected to replace SIT in the field of high-frequency induction hardening.
Induction quenching machine tool
Induction quenching machine tools tend to be more automatic, CNC control gradually increased, automatic inspection parts and automatic identification into the machine parts of the function of more machine tools.
Universal hardening machine
Universal quenching machine tools are developing towards flexibility. A quenching machine can be used for induction heating and quenching of different parts with different performance requirements. A crankshaft quenching machine developed in Germany, the flange induction quenching flexible machining system is slightly adjusted to handle similar workpiece of different sizes; For shaft parts within a certain diameter range (such as 30mm) and a length of 300 ~ 800mm, for shaft parts with similar quenching requirements, the quenching function automatically programmed 14 kinds of programs to automatically identify the incoming parts; Robotron. Biotherm recently launched a double spindle vertical quenching machine, in a compact process unit for the workpiece quenching and tempering, can handle the wheel shaft, three slot sleeve, and other universal joint parts, the workpiece conversion only 2 to 5 minutes, with computer programming, according to the workpiece number in 2 minutes can be called out the relevant process data; GH CNC quenching equipment introduced by FAW has strong universality and automation, which can realize multi-stage variable power transmission on complex parts, easy to program and easy to operate. Figure 1 is the CNC quenching machine tool of GH Company.
Special quenching machine
Special quenching machine more specialized, the use of manipulator upper and lower parts, heating, quenching, tempering, straightening, inspection fully automatic. Advanced computer control technology to monitor and screen display quenching process and the process parameters, tracking all the operation process, such as troubleshooting deviates from the given value or process parameters, automatic lists the non-conformity spare parts, automatic correction or to suspend work of control system and alarm, at the same time the nature of the fault screen and correction action. The more advanced control system also ADAPTS to fluctuations in the chemical composition of the material and automatically adjusts the specific power or heating time to ensure the quality of the induction hardened parts. For example, the horizontal half shaft quenching machine tool in the Kawasaki plant of Japan High Frequency thermal Refining Co., LTD., can simultaneously quench three half shafts in the upper tail plant and two half shafts in Gunma plant. The machine tool is actually an induction heat treatment production line, and the whole process is carried out automatically except for straightening and fluorescent inspection, which requires one worker.
Application of robots
A robot is equipped with a vertical general-purpose quenching machine made by Japan High Frequency Heat Treatment Co., LTD. The robot will scan a two-turn sensor in order to discolor a plastic plate. Although the power is only 3kW, the application trend of the robot in induction heat treatment can also be seen.
The power supply, quenching machine, and cooling system are combined into a complete set of equipment, which has the advantages of small floor space, high production efficiency, and easy installation and debugging. The area occupied by the crankshaft fixed heating quenching device recently introduced abroad is only 1/4 of that of the combined set.
Static crankshaft induction quenching process
The initial two devices using the new static crankshaft induction quenching technology have been applied in the quenching and tempering process of Crankshaft in Ford V6 and V8, showing a good market prospect. Its characteristics are short heating time, generally only 1.5 ~ 4s, the traditional process is 7 ~ 12s; High electrical efficiency and low cost; Large gap is allowed between inductor and workpiece to facilitate adjustment; Simple operation, good repeatability, easy to maintain; It covers a small area, only about 20% of the original.
Quench steel gears with low hardenability
Low hardenability steel is widely used in many Russian automobile factories for overall induction heating surface quenching. It has been widely used in automobiles, tractor rear axle gear, excavator gear, transmission cross shaft, rolling bearings for train cars, automobile plate spring, railway spiral spring and so on, and has achieved great economic benefits.
Double frequency induction hardening
Double frequency quenching is mainly used in gear abroad. In the 1990s, the United States used 10kHz if and 150kHz HF power supplies. The gear was first heated in the IF sensor, then rapidly cooled down in the HF sensor, and finally fell into the oil and quenched.In the 21st century, new progress has been made in this process. For example, the GH company adopts a power electronic switch to change frequency, which makes the heating of tooth tip and tooth heel more uniform and better guarantees the quenching quality of gear.