菜单
  
    To produce thin walled products in a precise and stable manner, FANUC have developed electric injection moulding machines driven by a rotary or linear motor to meet the particular features required for moulding products such as wall thickness, or type of plastic material. In this paper, the features necessary for each type of injection unit are introduced together with moulding examples.21615
    Introduction
    As a result of the increasing development of the IT
    industry, the demand for small and light or ultra precision
    products is increasing. This trend is also significant in the
    plastic moulding industry, and the development of
    thinner or higher precision products continues.
    Typical plastic products include tiny memory chip
    holders, or battery cases for mobile phones or digital
    cameras. To produce such thin moulded products, a
    ‘total technology’ – combination of mould, material and
    injection moulding machine technology – is required.
    In particular, for the injection moulding machine, a high
    speed and high acceleration capability is required to inject
    the mould cavity with molten material in very short fill times.
    Basic injection moulding machine
    performance required to produce thin
    walled products
    In injection moulding, injected molten material forms a
    skin along the mould surface by cooling, and this results
    in blocking of the material flow.
    In the case of thin walled products, the skin forms
    quickly because of the narrow cavity, so it is necessary to
    fill the cavity in a very short time. Furthermore, in the
    latter phase of the injection process, high pressure is also
    necessary to pack the cavity through the narrowing flow
    channel in the cavity caused by skin formation.
    Figure 1 shows injection speed and injection pressure
    for the injection stage in the case of moulding of a
    cellular phone battery case. As mentioned before, the
    injection pressure increases rapidly with time in the
    injection stage. Therefore, the injection moulding
    machine has to have a high injection speed and a high
    acceleration injection capability, so that shorter injec-
    tion times can be achieved accurately. Furthermore, it
    can achieve relatively easy filling by increased shear rate
    and hence lower polymer viscosity.
    One approach to attempt to achieve the required high
    injection speed and cavity filling is to use a hydraulicinjection moulding machine with an accumulator, which has
    explosive power generated by releasing accumulated hydrau-
    lic pressure. However, this was found to have a problem with
    repeatability because of inconsistency of speed or pressure
    influenced by hydraulic oil temperature variation.
    To resolve the issue, as a replacement for the
    hydraulic machine, a high injection speed and high
    acceleration injection capability electric injection mould-
    ing machine is required. This has been the most popular
    choice for the high precision moulding field.
    Classification of thin walled parts and
    injection performance requirement
    In general, there is no specific definition of thin walled
    moulding products by wall thickness. However, thin
    walled processing can be classified in practice into two
    groups, by recommended injection speed. Products such
    as a cellular phone battery cells or light guide panels,
    with 0.
    2to0.
    4 mm wall thickness can be classified in the
    first group, where 500 to 800 mm s
    –1
    injection speed and
    an injection pressure of 3000 kgf cm–2
    or more are
    required. The tiny memory or speaker cone with wall
    thickness 0.
    2 mm or less can be classified in the second
    group. To produce such thin walled moulding products,
    injection speeds of 1000 mm s
  1. 上一篇:钢筋在混凝土中的受压英文文献和中文翻译
  2. 下一篇:暖通空调系统优化英文文献和中文翻译
  1. 汽车乘员舱的声振耦合英文文献和中文翻译

  2. 立体光照成型的注塑模具...

  3. 低频振动的铁路车轴的状...

  4. 接头的形状对沥青塞接头...

  5. 电-气动驱动的垂直计算机...

  6. 开口端纺纱系统中的锥形...

  7. 木质填料聚丙烯复合材料...

  8. 当代大学生慈善意识研究+文献综述

  9. 电站锅炉暖风器设计任务书

  10. 中考体育项目与体育教学合理结合的研究

  11. 杂拟谷盗体内共生菌沃尔...

  12. 大众媒体对公共政策制定的影响

  13. java+mysql车辆管理系统的设计+源代码

  14. 酸性水汽提装置总汽提塔设计+CAD图纸

  15. 乳业同业并购式全产业链...

  16. 十二层带中心支撑钢结构...

  17. 河岸冲刷和泥沙淤积的监测国内外研究现状

  

About

751论文网手机版...

主页:http://www.751com.cn

关闭返回