热渐进成形中加热方式及其测温方法的研究进展

Research Progress of Heating and Temperature Measurement Methods in Thermal Progressive Forming

渐进成形是一种先进的制造技术,可满足小批量产品高精高效的生产需求。在航天航空、电子及精密仪器领域中的部件通常具有轻质高强的特点,但在室温下整体延展性较差的材料(钛合金、镁合金、铝合金)很难通过传统的渐进成形方法来成形,使用热辅助方法就显得尤为重要。简要介绍了渐进成形技术的发展及成形原理,并综述了国内外研究学者在热渐进成形技术中使用的加热方法,将其分为两种类型:整体加热和局部加热,进一步对比分析了两种加热方式的优缺点,其中,电加热方式适用范围较广且加热温度较高,加之其设备结构简单,具有较大的应用前景。在此基础上,针对不同加热方式,综述了相应的成形装置及温度测控方式,测温方式分为接触式测温和非接触式测温。对比两种测量方法,接触式测温精度高且测温范围较大,但难以测量运动中物体的温度;非接触式测温通常用于测量运动中的物体和小范围内的温度,并且不会对被测物体的温度场造成影响,但其制造成本较高且测量精度相对较低。分析了各种成形装置及温度测控系统的适应工况,将温度控制在材料成形的最佳温度附近可以提高材料的成形性和成形精度。

Progressive forming is an advanced manufacturing technology, which can meet the production requirements of small batch products for high precision and efficiency. Components used in aerospace, electronics and precision instruments are usually characterized by light weight and high strength, but the materials with poor overall ductility at room temperature(titanium alloy, magnesium alloy and aluminum alloy) are difficult to be formed by the traditional progressive forming methods, so it is particularly important to use the heat assisted method. The development of progressive forming technology and forming principle were briefly introduced, and the heating methods put forward by Chinese and foreign researchers for the thermal progressive forming technology were summarized, including two types: integral heating and local heating. Furthermore, a comparative analysis was carried out on the advantages and disadvantages of the two heating methods. The electric heating method was suitable for a wide range, with a higher heating temperature and a simpler equipment structure, which had many potential applications. On this basis, for different heating methods, the corresponding forming devices, temperature measurements and control methods were summarized. The temperature measurement methods were divided into contact and non-contact temperature measurement. According to the comparison results of the two temperature measurement methods, contact temperature measurement was usually used for the objects with high temperature measurement accuracy and a large temperature range, but it was difficult to measure the temperature of moving objects. Non-contact temperature measurement was usually used to measure the temperature of moving objects with a small temperature range, and would not affect the temperature field of the measured object,but its manufacturing cost was high and the measurement accuracy was relatively low. Through the analysis on the suitable working conditions of various forming devices and temperature measurement and control systems, it is concluded that controlling the temperature near the optimum temperature for material forming can improve the formability and forming accuracy of the material.