絮状粉末制品微量高精度称重系统设计与试验

Micro high precision weighing system for flocculent powder products

为了解决絮状粉末制品在定量称重中遇到的结团问题,以及称重过程中速度与精度的矛盾问题,采用改进机械结构和控制分阶段称量的方法来提高称重精度,设计了一种基于工业PLC的絮状粉末制品微量高精度称重系统。首先,称重系统的机械结构采用心形搅拌片和下料螺杆结合的螺旋送料方式,在一定程度上克服了橡胶粉末称重时的结团问题;然后,采用FX3U-32MT-E型号PLC作为整个电路的核心,及时处理反馈的重量信息,并向执行机构发送指令;称重系统的软件方面则根据重量信息控制下料电机的转速,实现了分阶段下料,提高了称重的精度;最后,对不同含水量的橡胶粉末进行了称量试验,以此来验证该絮状粉末制品微量高精度称重系统的有效性。研究结果表明:该称重系统在称量含水量6%以上的橡胶粉料时,称重误差能够稳定在250 mg内,称重值标准差控制在0.21 g以内,最大相对误差控制在2.5%以内,且称重速度达到12 s/次~14 s/次,所测得的称重速度和精度能够满足橡胶粉末的自动称重要求。

In order to solve the agglomeration problem and the contradiction between speed and precision in the quantitative weighing of floccule powder products,a micro-high precision weighing system based on industrial PLC was designed.The methods of improving the mechanical structure and controlling the weighing by stages were adopted by this system.In terms of mechanical structure,the agglomeration problem occurred during the rubber powder weighing could be overcome by the spiral feeding mode combining with heart-shaped agitator and feeding screw to a certain extent.FX3U-32MT-E PLC was adopted as the core of the whole circuit,the feedback weight information was dealt with in time,and instructions were sent to the actuator.According to the weight information,the laying-off motor speed was controlled by the software to realize the laying powder products in stages and improve the weighing precision.Finally,the weighing test of rubber powder with different moisture content was carried out,in order to verify the effectiveness of the micro high-precision weighing system for flocculent powder products.The research results show that when weighing rubber powder with more than 6%moisture content,the weighing error can be stabilized within 250 mg,the standard deviation of weighing value can be controlled within 0.21 g,the maximum relative error can be controlled within 2.5%,and the weighing speed can reach 12~14 seconds per time.The measured weighing speed and accuracy can meet the requirements of automatic weighing rubber powder.