1、附录： 英汉互译 塑料压缩模 在压缩成型过程中，塑料原料是以粉状或锭料形式放臵在加热的金属模具型腔中。因为分型面是水平面，上模就垂直下行。闭合模具后，预成型加压加热作用一段时间。在压力为 23t/in 和温度为华氏温度 350 的作用下，是塑料呈半液态，充满模具型腔。虽然近年来开发的酚醛树脂可在 25S 内塑化，但塑料通常的塑化需要 115min。最后开模取出塑件。如果零件中含有金属嵌件，应在注入塑料前，讲嵌件放入型腔定位孔中。锭料在装入模腔前预热出去气体，增强流动性，以便于充满模具和缩短塑化时间。电介质加热时加热锭料的便利方法。 因为塑料是直接加入模具型腔中的，所以压缩模比其他模塑料工艺的模
2、具简单，不需要浇道和浇口，可以节省原料，因为清理浇道和浇口，对热固性塑料来说是极大的浪费。用于压缩模塑的压力机通常是垂直液压机。较大的压力机要求操作者全神贯注地操作；然而，一个操作者可以同时操作几台小型压力机，因此压力机要合理放臵以便操作者能够方便你从一台到另 一台进行操作，操作者要保证当他再次绕道特定压力机前时，模具恰好准备开模。 热固性塑料在加热和加压作用下固化，这个特性决定其适合压缩模和传递模。因为压缩模要交替的加热和冷却，所以热塑性塑料实际上不是用于压缩成型。为了使热塑性塑料之间硬化并从型腔中顶出，就需要将塑件冷却。 压缩模的类型。用于压缩的模具可分为四种基本类型，分别是 :不溢式压缩
3、模、挡环不溢式压缩模、溢式压缩模和半溢式压缩模。在不溢式压缩模中，柱塞式凸模随上模进入下模模腔成型，因为下模没有挡环或限位装臵，柱塞式凸模继续下行以全部压力施加在塑料上，这样就 成产出具有良好电性能和物理性能的致密塑件。加入模腔的塑料剂量须精确计量，以为其影响零件的壁厚。挡环不溢式压缩模与不溢式压缩模类似，只是在预定点处增加了挡环，使柱塞式凸模在预定点停止运动，在这种模具中挡环吸收了原应作用在零件上的部分压力。这种压缩模可精确控制零件的壁厚，但是塑件密度的变化是相当大的。在溢式压缩模中，溢料会增加上下模的尺寸。当上模对塑料施压时，多余的塑料会从分型面处溢出。对溢料进一步施压，他就硬化最后在上模
4、形成飞边。生产致密塑件通常需要使用的计算量稍多的原料来增加压力。这种类型的模具之所以在生产 中广泛采用，是因为它想对比较容易制造，并能够控制塑件的厚度和致密度，使其更接近要求。半溢式压缩模是溢式压缩模和不溢式压缩模的组合类型，除了飞边外，采用的挡环可限制上模的移动。 注塑模重要性 1塑料具有密度小、质量轻、比强度大、绝缘性好、介电损耗低、化学稳定性强、成型生产率高和价格低廉等优点，在国民经济和人民日常生活的各个领域得到了日益广泛的应用，早在二十世纪九十年代初，塑料的年产量按体积计算已经超过钢铁和有色金属年产量的总和。在机电（如所谓的黑色家电）、仪表、化工、汽车和航天航空等领域，塑料已成为金属的
5、良 好代用材料，出现了金属材料塑料化的趋势。 2以汽车工业为例，由于汽车轻量化、低能耗的发展要求，汽车零部件的材料构成发生了明显的以塑代钢的变化，目前我国汽车塑料占汽车自重的 5%至 6%，而国外已达 13%，根据专家预测，汽车塑料的单车用量还将会进一步增加。在现代车辆上，无论是外装饰件、内装饰件，还是功能与结构件，都可以采用塑料材料，外装饰件有保险杠、挡泥板、车轮罩、导流板等；内装饰件有仪表板、车门内板、副仪表板、杂物箱盖、座椅、后护板等；功能与结构件有油箱、散热器水室、空滤器罩、风扇叶片等。据统计，我国 2000 年汽车产量 200 多万辆，车用塑料达 138 万吨。从国内外汽车塑料应用的
6、情况看，汽车塑料的用量现已成为衡量汽车生产技术水平的标志之一。 3作为塑料制件最有效的成型方法之一的注塑成型由于可以一次成型各种结构复杂、尺寸精密和带有金属嵌件的制品，并且成型周期短，可以一模多腔，生产率高，大批生产时成本低廉，易于实现自动化生产，因此在塑料加工行业中占有非常重要的地位。据统计，塑料模具约占所有模具（包括金属模）的 38.2%，塑料制品总重量的大约 32%是用于注射成型的， 80%以上的工程塑料制品都要采用注射成型方式生产。 4根据海关统计，我国 2000 年共进口模具 9.77 亿美元，其中塑胶模具共 5.5亿美元，占 56.3%， 2001 年共进口模具 11.12 亿美元
7、，其中塑胶模具共 6.16 亿美元，占 55.4%。从品种上来说，进口量最大的是塑胶模具。 Compression Molding for Plastics In compression molding the palstic material as powder or preforms is placed into a heated steel mold cavity,Since the parting surface is in a horizontal plane ,the upper half of the mold descends vertically.It closes the
8、mold cavity and pressures for a predetermined period.A pressure of from 2 to 3 tons square inch and a temperaure at approximately 350F converts the plastic to a semiliquid which flows to all parts of the mold cavity.Usually from 1 to 15 minutes is required for curing,altough a recently developed alk
9、yd plastic will cure in less than 25 secends. The mold is then opended and the molded part removed.If metal insers are desired in the parts,they should be placed in the mold cavity on pins or in the holes before the plastic is loaded.Also, the preforms should be preheated before loading into the mol
10、d cavity to eliminate gases,inproveflow,and decrease curing time.Dieletric heating is a convenient method of heating the preforms. Since the plastic material is placed directly into the mold cavity,the mold itself can be simpler than those used for other molding precesses.Gates and sprues are unnece
11、ssary.This also results in a saving in material,because trimmed-off gates and sprues would be a complete loss of the thermosetting plastic.The press require the full attention of one operator.However,several smaller presses can be operated by one operator. The presses are conveniently located so the
12、 operator can easilymove from one to the next.By the time he gets around to a particular press again,that mold will be ready to open. the thermosetting plastics which harden under heat and pressure are suitable for compression molding and transfer molding.It is not practical to moidshermoplastic mat
13、erials by these methods,since the molds would have to be alternately heated and cooled.In order to harden and eject thermoplastic parts form the mold,cooling would be necessary. Types of molds for compression molding.The molds used for compression molding are classified into four basic types,namely,
14、positivemolds,landed positive mold,flash-type molds,andsemipositivemolds.In a positive mold the plunger on the upper mold enters the lower mold cavity.since there are no lands or stops on the lower die ,the plunger completely trap the plastic material and descends with full pressure on the charge.A
15、dense part with good electrical and physical properties is produced.The amount of plastic placed in the die cavity must be accurately measured,since it determines the thickness of the part .A landed positive mold is similar to a positive mold except that lands are added to stop the travel of the plu
16、nger at predetermined point.In this case,the lands absorb some of the pressure that should be exerted on the parts.The thickness of the parts will be accurately controlled,but the density may vary cansideraby.In a flash-type mold,flashredges are added ti the top and bottom molds.As the upper mold ex
17、erts pressure on the plastic,excess material is forced out between the flash ridges where it forms flash.This flash is further compressed.becomeshardened,and finally stops the downardthavel of the upper mold.A slight excess of the plastic material is always chared to ensure sufficient pressurs to pr
18、oduce a dense molded part.This type of mold is widely used because it is comparatively easy to construct and it controls thickness and density within colselimits.Thesemipositive mold is a combination od the flash type and landed posivemolds.In addition to the flash ridges,a land is employed to restr
19、ict the travel of the upper mold. 一、 Injects the mold the importance 1. Plastics have the density small, the quality light, the specific tenacity big, the insulating property good, the dielectric loss low, the chemical stability strong, the formation productivity high and the price inexpensive and s
20、o on the merits, obtained day by day the widespread application in the national economy and peoples daily life each domain, as early as in the beginning of 1990s, the plastic annual output already surpassed the steel and iron and the non-ferrous metal annual output sum total according to the volume
21、computation.In mechanical and electrical (for example so-called black electrical appliances), domains and so on measuring appliance, chemical, automobile and astronautics aviation, the plastic has become the metal the good substitution material, had the metal material plastic tendency. 2. Take the a
22、utomobile industry as the example, as a result of the automobile lightweight, the low energy consumption development request, the automobile spare part material constitution occurred obviously has modelled the band steel the change, at present our country automobile plastic accounts for 5% which the automobile was self-possessed to 6%, but overseas has reached 13%, forecast according to the expert,
