注塑成型过程外文文献翻译、中英文翻译
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附录 1:外文翻译
介绍
如今塑料在日常生活中占据着极其重要的地位。
如果我们说,没有哪个领域的塑料没有不经过制造中直接到宇宙飞船的生产中,这一点也不夸张。
在19 世纪中叶,塑料开始在材料和生活中起主导作用。
耐腐蚀性是塑料甚至成为金属和提高制造生产率方面受到了很高的关注。
从塑料的紧缺,因此在塑料产品设计等各个方面发生巨大的变革,在制造加工领域还在测试阶段,现在,由于很多人最后通过体力劳动取得了卓越的成效,另外人工智能的帮助下,开发出了CAD / CAM 软件。
由于高强度的重量比,提高了化学稳定性和耐温性,具有耐热和耐腐蚀的特性,光泽性使其成为材料更好的选择。
塑料在形成过程中消耗的能量更少,并且可以被循环利用。
今天,塑料正在取代黄铜、铜、铸铁、钢铁等金属。
塑料可以根据制造方法分类,在加热时软化,在冷却时凝固。
这些被称为“热塑性塑料”,以及那些由于化学变化而变硬的物质。
这些被称为热固性或混合型塑料材料成为产品选择特殊材料是另一个重要因素。
这对于产品的确定是非常必要的。
它也应该能够承受压力。
每种材料都有自己的属性。
一些材料在高环境和耐磨性方面比较好。
困难的是找到一种合适材料,它将完全满足整个要求。
所以材料应该是通用的,它适合我们产品的所有考虑条件和要求。
在考虑了所有这些点的材料之后,必须选择合适的材料来满足所有这些条件。
注塑成型过程
它是一种通过将熔融状态的物质注入模具来生产零件的生产工艺。
注射成型被用在很多领域进行生产,包括金属、眼镜、弹性体、糖果以及最常见的热塑性塑料和热固性塑料。
将材料的一部分送入一个加热的桶,混合,并用高压压入一个模腔,它是可以冷却和硬化地方。
在产品设计后,通常由工业设计师或工程师设计模具,模具由模具制造商(或工具制造商)制造,通常由金属或铝制成,并经过精密加工以形成所需的特性。
注塑成型广泛应用于制造各种零件,从最小的零件到汽车的整个车身。
零件的形状和特点、模具的所需材料,以及造型机的性能都必须考虑在内。
注塑成型有利于发展,它是通过考虑设计和注射成型的可能性,利用一个活塞或螺旋型柱成型机用压力使熔融塑料材料进入模具型腔;
然后凝固成一个形状,它符合模具的轮廓。
它是最常用于热塑性和热固性聚合物的处理,前者在每年生产的材料的数量上相当多。
注塑成型包括将原料压入模具中,将其塑成理想的形状。
模具可以是单个腔或多个腔。
在多个空腔模具中,每个腔体可以是相同的,可形成相同的零件,在一个的周期内形成多个不同尺寸外形。
模具一般由工具钢制成,但不锈钢和铝制模具适用于某些方面的应用。
铝制模具通常不适合大批量生产或尺寸较小的零件,因为它们的机械性能较差,在注射和夹紧一段时间后更容易磨损、损坏和变形;但在小体积零件的应用中,由于模具制造成本和时间大大减少,成本太高。
许多钢制模具再起使用寿命内被设计用来生产超过一百万件的零件,并且需要花费数十万美元来制造。
当热塑性塑料成型时,是将原材料通过一个料斗进入料桶中加热在螺杆的作
用下搅拌。
在进入料桶时,热能增加,而由于较高的热能使分子间的间隔增加,抑制单个链的相对流动的范德华力也会减弱。
这降低了它的粘度,使聚合物流动能与注射装置的驱动力增加。
螺杆输送原料,将聚合物的热和粘性分布混合均匀,减少所需的加热时间,通过机械剪切材料,并在聚合物上添加大量的摩擦加热。
这种材料通过一个止回阀向前进,并在螺旋的前部收集到一个可注入的量。
射孔是用来填充模具型腔的材料体积,补偿收缩,并提供一个缓冲垫(大约占总弹量的10%,始终在料桶内,防止螺丝从底部流出)将压力从螺杆转移到模具型腔。
当收集到足够的材料时,材料就会在高压和快速度进入形成腔的部分。
为了防止压力太高,这个过程通常利用一个对应于95-98%全空腔的传输位置,在那里,螺旋从一个恒定的速度转变为一个恒压控制。
通常注射次数在1 次以下。
一旦螺杆到达传递位置,就会应用填料压力,完成模具的填充和热收缩补偿,这对于热塑性塑料相对于其他材料来说是相当高的。
填料压,直到浇口(腔口)凝固。
由于其体积小,通常浇口是首先要经过的地方凝固过程中。
一旦浇口凝固,就不会有更多的材料进入腔体,螺杆往复并获得下一个周期的材料,而模具内部的材料冷却,使其能够被弹射并保持尺寸稳定。
冷却时间大大减少,使用冷却管路循环的水或油来降温。
一旦温度达到要求,模具就会打开,并有一系列的销、套筒、脱模机等被推进去模具惊醒脱模。
然后,模具关闭,这个过程有一个分型线,浇口,浇口痕迹,和注塑模顶出销迹印通常出现在最后的部分被重复。
这些特性都是所需要的。
铝模具的成本要低得多,而且在设计和加工的时候都是现代的。
计算机化的设备可以节约几十甚至几十万件零件。
铍铜用于需要快速散热的模具区域,或者是产生最多剪切热量的区域。
模具可由CNC 加工或使用放电加工制造。
模具设计
采购塑料模具钢时,要按照具备良好的机加工性能,良好的抛光能力,良好的光泽性能,良好的电火花腐蚀性能,安全,简单的热处理,最低夹杂水平,一贯的高质量,技术上的帮助和在制造和应用方面的建议选择。
注塑模具钢结构的基本特性,如均匀结构和内部的自由,缺陷,机械性最大的自由不受热处理的变形,焊接能力,抛光能力,耐磨性和韧性,钢模具分为两类, 模具结构部分,中碳硅抵消锻造质量钢约25%的抗拉强度,典型的是低碳钢。
它被退火到大约165BHN。
在加工过程中,最小变形时应力消除。
AISI 4130 型合金钢是预加热到约300BHN,以承受闪光的喷丸效果。
它具有承重负荷和长时间生产的耐久性。
尼龙66 是一种由己二酸和六乙二
胺经缩聚而成的聚酰胺,尼龙66 具有韧性好、抗拉强度高、弹性好、耐热性好、耐磨性好、抗皱性好、耐化学性能好等特点。
在注塑成型过程中,收缩率是一定的的。
由于聚合物的密度随加工温度的变化而变化,因此会发生收缩。
收缩率将取决于塑料材料、加工条件、产品设计、模具设计。
考虑到尼龙66 的收缩率为1.018%。
在核心和型腔板的模具设计中,包含了这些尺寸。
流道的设计
如图所示常用的流道截面形状,全方位的流道是最好的。
在最大体积与表面比的条件,可最大限度地减少压降和热损失。
但是,模具成本却不高。
因为模具的两半部分都必须经过加工,以便在模具闭合时,两个半圆型截面都是一致的。
梯形的流道也能很好地工作,并且允许流道被设计在模具的一边。
它通常用于三板模具。
当全方位的流道可不能正确释放时,在模具的分型线处,模具滑动动作完全被干扰。
为了比较不同形状的流道,采用流道的流动效率(L)作为流动阻力的指标。
流道内熔体流动效率越高,流动阻力越小。
流动效率可定义为L = A/P,其中L =熔体通过一个流道的流动效率。
A =横截面面积。
P =周长。
一旦将熔融的塑料注入到模具型腔内,模具冷却后就需要足够的时间,使其变得足够坚硬,使其脱模。
这段时间被称为冷却时间,通常形成了一个重要的部分。
为了使模塑部件冷却固化,必须从模具中去除热量。
冷却水从模板的一边进入,循环然后离开。
这通常指的是填充分析或流量分析。
填充分析在填充部分填充到100%时停止。
流量分析是一种填充分析,但仍会继续通过填料,甚至是模具周期的冷却阶段。
在进行流量分析之前,我们可以通过填充分析来确定和解决一些模压问题。
解决装配问题通常是迭代过程,需要做一些分析。
一旦完成了第一个填充分析,就会对结果进行审查,并确定并修复一个问题。
这可能需要之前步骤的多次迭代。
在这里描述的序列中有一个主要的假设,即被处理的问题是一个填充相关的问题。
而不是填料、冷却或变形。
另一个问题也是通过迭代过程解决的,但是只有在填充优化之后。
一旦流道系统大小确定,零件的填料方式可以被更换。
虽然流量分析可以是无浇口或流道的,但并不是非常推荐。
浇口的冷却时间和运行时间对零件的包装有很大的影响。
对于流道和浇口,填料分析将不准确。
附录 2:外文原文
.Introduction
Now a day’s plastic are occupying a vital role in the day-to-day life. It is not at all can e×aggeration, if we say that there is no field into which plastic have not stepped in right from the manufacturing at a pin to that of a spacecraft. At the middle of 19th century, plastics start a leading role in the material and in our life.Corrosion resistance are some of the aspects through which plastics are even becoming superiors to metals and attained an elevated rate of preference in every branch of manufacturing. Right from the emergency of plastics they are undergoing drastic in various aspects like design of plastic product, manufacturing processing then in testing fields and now, because of fruitful efforts of many people at last the came in work through manual labor, but with help of artificial intelligence that is, with software package like CAD/CAM. Because of high strength of weight ratio, improve chemical and temperature resistance, inherent properties of being bath thermal and corrosion resistance, transparency have made them a material choice.
Plastic consume less energy during formation and can be profitably recycled. Today
plastics are replacing the metals like Brass, Copper, Cast Iron, Steel etc. Plastics can be classified according to manufacturing methods in to main groups Those which soften when heated and solidifies on cooling. These are known as “Thermo plastic” and
Those which harden when heated as a result of chemical change. These are known as Thermosetting or Duro plastic material” Selection of particular material for the product is another important factor. This is particularly very necessary for the product
determination. It should capable of withstanding stresses acted upon it as well. Each
material has its own properties and attributes. Some materials are better in high
environment and e×tremely abrasion resistance. The difficult part is to find a material that will come close to fulfilling the entire requirement of the purpose. So material should be so versatile that it suits all the consideration and requirement of our product. After considering all these point’s material must be selected suitable enough to satisfy all these conditions.
Injection Moulding Process
It is a manufacturing process for producing parts by injecting liquid molten material into a mould. Injection moulding can be performed with a host of materials, including Metals, Glasses, Elastomers, Confections and most commonly Thermoplastic and Thermosetting polymers. Material for the part is fed into a heated barrel, mi×ed, and forced into a
mould cavity where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mould maker (or toolmaker) from metal, usually either steel or aluminum, and
precision-machined to form the features of the desired part. Injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. The part, the desired shape and features of the part, the material of the mould, and the properties of the moulding machine must all be taken into account. The versatility of injection moulding is facilitated by this breadth of design considerations and
possibilities Injection molding utilizes a ram or screw-type plunger to force molten plastic material into a mold cavity; this solidifies into a shape that has conformed to the contour of the mold. It is most commonly used to process both thermoplastic and thermosetting polymers, with the former being considerably more prolific in terms of annual material volumes processed. Injection molding consists of high pressure injection of the raw material into a mold which shapes the polymer into the desired shape. Molds can be of a single cavity or multiple cavities. In multiple cavity molds, each cavity can be identical and form the same parts or can be unique and form multiple different geometries during a single cycle. Molds are generally made from tool steels, but stainless and aluminum molds are suitable for certain applications. Aluminum molds typically are ill-suited for high volume production or parts with narrow dimensional tolerances, as they have inferior mechanical properties and are more prone to wear, damage, and deformation during the injection and clamping cycles; but are cost-effective in low-volume applications as mold fabrication costs and time are considerably reduced. Many steel molds are designed to process well over a million parts during their lifetime and can cost hundreds of thousands of dollars to fabricate. When thermoplastics are molded, typically pelletized raw material is fed through a hopper into a heated barrel with a reciprocating screw. Upon entrance to the barrel the thermal energy increases and the Vander Waals forces that resist relative flow of individual chains are weakened as a result of increased space between molecules at higher thermal energy states. This reduces its viscosity, which enables the polymer to flow with the driving force of the injection unit. The screw delivers the raw material forward, mi×es and homogenizes the thermal and viscous distributions of the polymer, and reduces the required heating time by mechanically shearing the material and adding a significant amount of frictional heating to the polymer. The material feeds forward through a check valve and collects at the front of the screw into a volume known as a shot. Shot is the volume of material which is used to fill the mold cavity, compensate for shrinkage, and provide a cushion (appro×imately 10% of the total shot volume which remains in the barrel and prevents the screw from bottoming out) to transfer pressure from the screw to the mold cavity. When enough material has gathered, the material is forced at high pressure and velocity into the part forming cavity. To prevent spikes in pressure the process normally utilizes a transfer position corresponding to a 95–98% full cavity where the screw shifts from a constant velocity to a constant pressure control. Often injection times are well under 1 second. Once the screw reaches the transfer position the packing pressure is applied which completes mold filling and compensates for thermal shrinkage, which is quite high for thermoplastics relative to many other materials. The packing pressure is applied until the gate (cavity entrance) solidifies. The gate is normally the first place to solidify through its entire thickness due to its small size. Once the gate solidifies, no more material can enter the cavity accordingly, the screw reciprocates and acquires material for the ne×t cycle while the material within the mold cools so that it can be ejected and be dimensionally stable. This cooling duration is dramatically reduced by the use of cooling lines circulating water or oil from a thermolator. Once the required temperature has been achieved, the mold opens and an array of pins, sleeves, strippers, etc. are driven forward to de mold the article. Then, the mold closes and the process is repeated A parting line, sprue, gate marks, and ejector pin marks are usually present on the final part. None of these features are typically desired, but are unavoidable due to the nature of the process. Gate marks occur at the gate which joins the melt-delivery channels
(sprue and runner) to the part forming cavity. Parting line and ejector pin marks result from minute misalignments, wear, gaseous vents, clearances for adjacent parts in relative motion, and/or dimensional differences of the mating surfaces contacting the injected
polymer. Mold or die are the common terms used to describe the tool used to produce plastic parts in molding.Sincemolds have been e×pensive to manufacture, they were usually only used in mass production where thousands of parts were being produced. Typical molds are constructed from hardened steel, prehardened steel, aluminum, and/or beryllium-copper alloy. The choice of material to build a mold from is primarily one of economics; in general, steel molds cost more to construct, but their longer lifespan will offset the higher initial cost over a higher number of parts made before wearing out.
Pre-hardened steel molds are less wear-resistant and are used for lower volume requirements or larger components; their typical steel hardness is 38–45 on the Rockwell-C scale. Hardened steel molds are heat treated after machining; these are by far the superior in terms of wear resistance and lifespan. Typical hardness ranges between 50 and 60 Rockwell-C (HRC).Aluminum molds can cost substantially less, and when designed and machined with modern computerized equipment can be economical for molding tens or even hundreds of thousands of parts. Beryllium copper is used in areas of the mold that require fast heat removal or areas that see the most shear heat 2 generated. The molds can be manufactured either by CNC machining or by using electrical discharge machining processes.
Mould Die Design
When purchasing plastics mould steels, one looks, for Good machining properties, Good polish ability, Good photo –etching properties, Good spark erosion properties, Safe, uncomplicated heat treatment, Minimum inclusion level, Consistently high quality, Technical assistance and advice in tool in manufacturing and application.. Essential characteristic of injection mold steel like Uniform structure and freedom from internal, defects, Machinability Ma×imum freedom from distortion during heat treatment, Weld ability, Polish ability, Wear resistance and toughness, Steels for mould fall under two categories, Structural section of the mould, Medium carbon silicon killed forging quality steel with appro×imately 25% greater tensile strength then typical low carbon steel. It is annealed to appro×imately 165BHN. It is stress relieved for minimum deformation during machining.AISI 4130 type alloy steel is supplied pre-heated to appro×imately 300BHN to withstand the peening effect of flash. It has durability for heavy construction loads and long production runs. Component material is selected as NYLON-66, Nylon 66 is a polyamide made from adipic acid and he×amethylenediamine by polycondensation,NYLON-66 has Good toughness, High tensile strength, High elasticity, Good heat resistance, E×cellent wear resistance, Wrinkle proof and e×cellent chemical resistance.Shrinkage is inherent in the injection moulding process. Shrinkage occurs because the density of polymer varies from the processing temperature to the ambient temperature. The shrinkage factor will depends on Plastic material, Processing condition, Product design, Mould design. Shrinkage allowance of Nylon 66 is 1.018% considered. This total dimensions are incorporated in the mould designing of core and cavity plate. Runner Design
The trapezoidal runner also works well and permits the runner to be designed cut on one side of the mould. It is commonly used in three plate moulds. Where the full-round runner may not be released properly, and at
the parting line in moulds, where the full interferes with mould sliding action. To compare runners of different shapes, the flow efficiency (L) of the melt through a runner, which is an inde× of flow resistance, is employed. The higher the flow efficiency of the melt through the runner, the lower the flow resistance is. Flow efficiency can be defined as L = A/P, Where L = flow efficiency of the melt through a runner. A = Cross section area. P = perimeter. Once molten plastic has been injected into the mould cavity, it takes time before the moulding has cooled and become sufficiently rigid to allow it to be demoulded. This period is called the cooling time and often forms a significant part of the moulding cycle. To allow a molded part to
cool and solidify, heat must be removed from the mould. The cooling water enters from one side of the plates, circulates and leaves. This normally refers to a fill analysis or a flow analysis.
A fill analysis stops when the part volume is just filled to 100%. The flow analysis is a fill analysis but continues through the packing and even cooling phases of the moulding cycle. We can identify and resolve a number of moulding issues using fill analysis before running a flow analysis. Solving filling problems is typically an iterative process
requiring several analyses. Once the first fill analysis is done the results are reviewed, and a problem is identified and fi×ed. This may require much iteration of previous steps.
There is one major assumption in the sequence described here, namely, that the problem
being addressed is a filling related problem. And not packing, cooling or warpage related. The other problem, too are solved by an iterative process,
but only after the filling is optimized. Once the runner system is sized, packing of the part can be investigated.
Although a flow analysis can be one without a gate or runner, it is not very much recommended. The freeze time of the gate and runners significantly affects the packing of the part. Without a runner and gate, the packing analysis will be less accurate.。