摘要
在分析不稳定挤出工艺和设备因素的影响和制品精密度的基础上 ,提出了精密挤出在轴向和横向的波动。数值分析和试验结果表明 ,通过将精密挤出理论和现代成型装备进行有机的结合 ,是能够实现将挤出制品精度提高 5 0 %以上的目标的。回顾了提高挤出制品精度的挤出理论和概念 ,提出为了实现精密挤出必须采取的一些必要手段 ,如熔体泵、压力波动控制器、并联式挤出压力稳定装置、采用电子差分变速技术的牵引装置和失重计量的加料装置等。初步研究结果表明 :精密挤出具有现实的可能和巨大的潜能 ,主要体现在 :传统的挤出机的温度控制在 3～ 5℃ ,这可以引起 9%～ 15 %的流率波动 ;挤出过程中 5 %～ 10 %的流率波动是由于错误的控温方式引起的 ;传统的带传动模式可以引起 0 .2 5 %～ 4%的流率波动 ;为保证高聚物具有稳定的熔融过程 ,精密挤出机的螺杆是采用抑制挤出机中频波动的原理进行设计的 ;熔体泵。
Based on analysis of influences of technological and equipment factors on the instabilities of extrusion and precision of the extrudate,the investigation on axial fluctuation and transverse fluctuation of the precision extrusion was carried out.Numerical analysis and experimental results indicate possibility to enhance the extrusion precision over 50 % by combination precision extrusion theory with modern mechatronics technology.The advances of extrusion theory and technology concerning improvement of the precision of extruded articles are reviewed.The effective technical means to realize precision extrusion involve melt pump,fluctuation control,parallel apparatus for stabilization of extrusion pressure,haul-off units with electrical differential driven system as an alternative to a mechanical differential,weight loss metering feeders,etc. It is proved by preliminary investigation that the precision extrusion has realistic possibility and tremendous potential.The preliminary investigation on precision extrusion indicated that:a.The control accuracy of temperature for ordinary extruders is about 3 ℃ to 5 ℃,which may cause fluctuation of the flow rate from 9 % to 15 %.b.The 5 % to 10 % fluctuation of the flow rate may be caused by inaccurate temperature control.c.The ordinary belt-driving pattern brings about a fluctuation of the flow rate from 0.25 % to 4 %.d.The screw of the precision extruder could be designed on the principle of depressing fluctuation of middle frequency to the utmost by guaranteeing steady melting.e.Melt pump,pressure fluctuation control and parallel apparatus for stabilization of extrusion pressure are effective for stabilizing the flow rate.
出处
《中国塑料》
CAS
CSCD
北大核心
2003年第2期1-8,共8页
China Plastics
基金
北京市自然科学基金资助项目 ( 30 2 2 0 0 8)
