1、3100 英文单词， 15500 英文字符 ，中文 4750 字 文献出处： Abdallah S, Abu-Mallouh R. Heating systems with PLC and frequency controlJ. Energy Conversion & Management, 2008, 49(11):3356-3361. Heating systems with PLC and frequency control Salah Abdallah, Riyad Abu-Mallouh Abstract In this work, medium capacity controlle
2、d heating system is designed and constructed. The programming method of control of heating process is achieved by means of integrated programmable logic controller (PLC) and frequency inverter (FI). The PLC main function is to determine the required temperatures levels and the related time intervals
3、 of the heating hold time in the furnace. FI is used to control the dynamic change of temperature between various operating points. The designed system shows the capability for full control of temperature from zero to maximum for any required range of time in case of increasing or decreasing the tem
4、perature. All variables of the system will be changed gradually until reaching their needed working points. An experimental study was performed to investigate the effect of tempering temperature and tempering time on hardness and fatigue resistance of 0.4% carbon steel. It was found that increasing
5、tempering temperature above 550 C or tempering time decreases the hardness of the material. It was also found that there is a maximum number of cycles to which the specimen can survive what ever the applied load was. Keywords: Heat treatment; PLC control; Frequency control ;Tempering 1. Introduction
6、 Heat treatment is the controlled heating and cooling of metals to alter their physical and mechanical properties without changing the product shape. Heat treatment is often associated with increasing the strength of material, but it can also be used to alter certain manufacturability objectives such as improve machining, improve formability, and restore ductility after a cold working operation. Thus it is a very enabling process that can not only help other manufacturing process, but can al
