Research And Development Of Electromagnetic Heater Of Olding Machine Screw

The heat of Electric heating circle is a widely used heating mode in today’s screwextruder. It transmits heat through contact conduction to the cylinder, but only thoseabut the inside surface can make use of it. The heat outside is easily lost in the air, andthe loss of heat conduction makes the rise in temperature. Besides, heating resistancewire has low power density, which makes it difficult to be use in high temperaturesituations. Therefore, the subject adopts the electromagnetic heating technology,which is more effective, faster and more controllable.This topic was based on electromagnetic heating, developing a10kw heatingcontrol system that applied the screw extruder, meanwhile, completing the design ofsoftware and hardware. In this paper, the design of hardware circuit includes switchpower supply circuit (multipath) DC power supply, main drive circuit, whole bridgedriving circuit, inverter circuit, and LC resonant circuit. The connection between thecircuits is as follows: Firstly,380V three-phase AC becomes DC through rectifying,which reduces voltage for switching power working. Finally switching circuit outputsMulti-channel voltage through transformer. Some of the voltage supply driving circuitfor it producing PWM wave form which drives optocoupler. Optocoupler connectswith invert circuit composed of IGBT. Eventually sinusoidal signal which is achievedby resonant circuit produces eddy current for charging barrel heating. IGBT is used asthe switch unit in the inverter circuit, and can work at the frequency of15to25KHZ.It is made up of uncontrollable three-phase bridge rectifier circuit and voltage typeone-way half bridge inverter circuit. And it uses pulse frequency to modulate PFM forconstant power of control.In this control system, Atmega16master control chip was used in the designwhich has watchdog and self-protective low voltage. Also, it can realize themanagement to the system’s work current, grid voltage and temperature, but also givefull consideration to the dead zone of IGBT drive isolation and relevant protection.Considering the drawbacks in the cylinder structure of screw extruder and theelectromagnetic induction heating system, we used circuit type heating mode in the project to improve the system’s safety and stability.Considering the complexity of the code, we adopted modular method in this plan,and modularized every part of the functional area that it concerned. Besides, we tookfull consideration of the system’s fault self-checking function, making it moreconveniently used through liquid crystal display in the Chinese language.Finally, we obtained the curves by experiment, meanwhile, the feasibility ofdesign was verified in comparison with the traditional heating mode.