什么是薄壁注塑？英文双语对照

何谓薄壁？ 简单的看法，当壁厚小于1mm时称为薄壁。

更全面地，薄壁的定义与流程/壁厚比、塑料的粘度及传热系数均有关系。

从模具的主流道到成品最远一点的流程L，除以成品的壁厚t，称为流程/壁厚比。

当L/t＞150时，称之为薄壁。

如流程的厚薄不一致，可分段计算。

流程/壁厚比 PP的粘度因数是1。

一次即弃饭盒的流程135mm，壁厚0.45mm，流程/壁厚比=300。

PC的粘度因数是2。

手机电池外壳的流程38mm，t=0.25mm，流程/壁厚比=152。

乘上粘度因数是304，与饭盒的相若。

一般塑料的导热不良。

为了增加散热效果或达到电磁波兼容性，一些外壳会采用高导热性的塑料。

金属粉末亦属于高导热性的。

上式是注塑成品的冷却时间公式，其中t=壁厚，Tm=溶融温度，TW=模壁温度，T=脱模温度，α=塑料传热系数。

L/t的定义要包括粘度因数及传热因数在内。

我来完善一下，？ 简述首先为何要薄壁注塑？ 塑料原料的成本通常占制品成本的一个大比数，如50-80%。

薄壁有助降低这个比数。

由于消费性电子设备如手机、MP3播放机、数码相机、掌上计算机的小型化及轻便化，有关的塑件设计便越来越薄。

薄壁化因具有减小产品重量及外形尺寸、便于集成设计及装配、缩短生产周期、节约材料和降低成本等优点成为塑料消费行业追求的目标，已成为塑料成型行业中新的研究热点。

工艺薄壁制品的设计思想和方法更为复杂，并进一步受到成型局限及材料选择的影响。

薄壁制品要求应该具有高的冲击强度、良好的外观质量和尺寸稳定性，并能承受大的静态载荷，成型材料的流动性要好。

设计过程中要重点考虑制品的刚性、抗冲击性和可制造性。

成型薄壁制品时一般需要专门设计的薄壁制品专用模具。

与常规制品的标准化模具相比，薄壁制品的模具从模具结构、浇注系统、冷却系统、排气系统和脱模系统等都发生了重大变化。

主要表现在以下几个方面： （1）模具结构：为承受成型时的高压，薄壁成型模具的刚度要大、强度要高。

因此模具的动、定模板及其支承板重量较大，厚度通常比传统模具的模板要厚。

支撑柱要多，模具内可能要多设置内锁，以保证精确定位和良好的侧支撑，防止弯曲和偏移。

另外，高速射出速度增加了模具的磨损，因此模具要采用较高硬度的工具钢，高磨损、高冲蚀区（如浇口处）硬度应大于HRC55。

（2）浇注系统：成型薄壁制品，特别是制品厚度非常小时，要使用大浇口，而且浇口应该大于壁厚。

如是直浇口应设置冷料井，以减少浇口应力，协助填充，减少制品去除浇口时的损坏。

为保证有足够的压力充填薄的模腔，流道系统中应尽可能减少压力降。

为此，流道设计要比传统的大一些，同时要限制熔体的驻留时间，以防止树脂降解劣化。

当是一模多腔时，浇注系统的平衡性要求远高于常规模具的要求。

值得注意的是薄壁制品模具的浇注系统中还引入了两项先进技术，即热流道技术和顺序阀式浇口（SVG）技术。

（3）冷却系统：薄壁制品不像传统壁厚件那样可以承受较大的因传热不均而产生的残余应力。

为保证制品的尺寸稳定性，把收缩和翘曲控制在可以接受的范围内，就必须加强模具的冷却，确保冷却均衡。

较好的冷却措施有在型芯及模腔模块内采用不闭合冷却线，加大冷却长度，均可增强冷却效果，必要的地方加入高传导率金属镶块，以加快热传导。

（4）排气系统：薄壁注塑成型模具一般需要有良好的排气性，最好可以进行抽真空操作。

由于填充时间短，注射速度高，模具的充分排气尤其是流动前沿聚集区的充分排气非常重要，以防困气引燃。

气体通常通过型芯、顶杆、加强筋、螺柱及分型面等处排出。

流道的末端也要充分排气。

日本Sumitomo公司用多孔工具钢做小嵌件来解决小件制品的排气问题。

（5）脱模系统：因为薄壁制品的壁和筋都很薄，非常容易损坏，而且沿厚度方向收缩很小，使得加强筋和其他小结构很容易粘合，同时高保压压力使收缩更小。

为避免顶穿和粘模，薄壁注塑成型应使用比常规注塑成型数量更多、尺寸更大的顶出销。

常规的注塑机很难在薄壁塑件注塑成型中有用武之地。

比如薄壁注塑成型的填充时间很短，很多填充时间不足0.5s，在这样短的时间不可能遵循速度曲线或截断压力，因此必须使用高解析度的微处理器来控制注塑机；在薄壁制品的整个注塑成型过程中，应同时各自独立地控制压力和速度，常规注塑机的充填阶段用速度控制，保压阶段再转为压力控制的方法已不适用。

所以机械设备制造商与研究机构共同合作努力，研制出了专用的注射设备。

如台湾中精机公司的VS-100薄壁注塑机、德国Dr．Boy公司开发的Boy型系列注塑机以及Battenfeld、Arburg和JSW等著名注塑机生产厂商开发的专用注塑机。

薄壁注塑成型材料流动性要好，必须拥有大的流动长度。

还有具有高的冲击强度，高热变形温度，良好的尺寸稳定性。

另外，还要考察材料的耐热性、阻燃性、机械装配性及外观质量等等。

目前，薄壁注塑成型广为应用的材料有聚碳酸酯（PC）、丙烯腈—丁二烯—苯乙烯（ABS）及PC/ABS共混物等。

技术常规注塑的填充过程和冷却过程是交织在一起的，当聚合物熔体流动时，熔体前沿遇到相对温度较低的型芯表面或型腔壁，就会在其表面形成一层冷凝层，熔体在冷凝层内继续向前流动，冷凝层厚度对聚合物的流动有着显著地影响。

需要对薄壁注塑成型中的冷凝层的性质进行更深入、更全面的研究。

因此有关薄壁注塑成型的数值模拟还需在以下几方面做很多工作。

（1）更深入全面研究薄壁注塑成型理论，尤其是冷凝层的性质，以便提出更加合理的假设条件和边界条件。

由上述分析可知，在薄壁注塑成型过程中，其很多条件和常规注塑成型有很大不同。

模拟时，熔体流动数学模型的许多假设和边界条件在薄壁注塑成型中需要进行适当的调整。

（2）确定在薄壁注塑成型中增加的因素，并正确地考虑这些因素。

一些在常规注塑中可以忽略的因素，往往会对薄壁成型熔体流动产生较大的影响。

比如，在薄壁注塑中粘度对压力有明显的依赖性，而在常规注塑成型中却没有；熔接线强度对塑件性能影响很大，尤其是薄壁塑件，熔接线强度与温度和压力有关，但常规数值模拟时没有考虑压力的影响；材料的比热、传热系数和压力损失等。

现有的商品化数值模拟软件由于忽略了这些影响因素，因而在预测薄壁注塑成型填充时会出现不一致的现象。

（3）应用真正的三维数值模拟。

现有商品化的数值模拟软件都是使用二维、二维半要素代表三维几何图形的简化模型，没有考虑物理量在厚度方向上的变化。

三维流动区域即拐角处流动、厚度变化区域、熔体前端喷泉效应在现有的数值模拟软件中还不能表示，而它们在薄壁注塑成型中起重要作用。

（4）注塑成型全过程模拟。

目前的模拟软件主要包括填充、流动、保压、冷却、和翘曲分析等模块，各模块的开发是基于各自独立的数学模型，忽略了相互之间的影响。

但是，从注塑成型工艺过程来看，塑料熔体的充模流动、保压和冷却等是交织在一起并相互影响的，这在薄壁注塑成型中尤为明显。

因此，充模流动、保压与冷却分析和翘曲模块必须有机地结合起来，进行耦合分析，才能综合反映实际的注塑成型。

(编辑：青华小黎)

What is meant by Bao Bi? Simple view, when the wall thick Bao Bi is called when be less than 1mm.

More comprehensive ground, bao Bi's definition and flow / the wall is large than, plastic viscosity and conduct heat coefficient all matters.

From the mainstream of the mould the flow L with a bit more farthermost finished product, divide the mural thick T with finished product, call flow / the wall is large than.

When L/t ＞ 150 when, say for Bao Bi.

If the thickness of flow is abhorrent, but section computation.

Flow / the wall is large the viscosity factor that compares PP is 1.

Abandon the flow 135mm of messtin namely, mural thick 0.45mm, flow / the wall is large than =300.

The viscosity factor of PC is 2.

The flow 38mm of crust of mobile phone batteries, t=0.25mm, flow / the wall is large than =152.

Multiply on viscosity factor is 304, the photograph with messtin if.

General and plastic heat conduction is undesirable.

Come loose to heat up the effect or achieve electromagnetic wave compatibility to increase, what a few crust can use tall thermal conductivity is plastic.

Metallic powder also belongs to tall thermal conductivity.

Type is the cooling time formula of the finished product that note model on, among them T= wall is large, temperature of Tm= dissolve be in harmony, temperature of TW= model wall, temperature of T= drawing of patterns, α = is plastic conduct heat coefficient.

The definition of L/t should include viscosity factor to reach conduct heat factor inside.

I will be perfected, ? Summarize why to want Bao Bi to note model above all? The cost of plastic raw material occupies a of product cost to compare number greatly normally, be like 50-80% .

Thin wall conduce reduces this to compare number.

Because if mobile phone, MP3 broadcasts the miniaturization of the computer on camera of machine, number, palm,consume sexual electron equipment,reach light change, concerned model design thinner and thinner.

Because have,Bao Bi is changed reduce product weight and over all dimension, facilitate compositive design is reached assemble, shorten manufacturing cycle, managing material and the goal that reduce the advantage such as cost to become plastic consumption industry to go after, already became plastic shape the new research heat in the industry.

The design thought of goods of craft thin wall and method are more complex, be shaped further confine and the influence that material chooses.

Thin wall goods asks to should have high impact strength, good exterior quality and dimension stability, can bear big static load, the fluidity that expects into profile is close friends.

The tigidity of goods, impact resistance and producibility should consider mainly in designing a process.

Shape the die for special purpose of thin wall goods that special design needs commonly when thin wall goods is provided.

With the standardization of groovy goods mould photograph is compared, the mould of thin wall goods provides structure, gating system, cooling system, exhaust system and system of drawing of patterns to waited to produce major change from the model.

Main show is in the following respects: (1) mould structure: The high pressure when shaping to bear, the stiffness of Bao Bicheng mould wants big, intensity tall.

Because of this mould move, calm pattern plate and weight of its backing plate are greater, ply wants than the pattern plate of traditional pattern normally thick.

The column that prop up wants much, the likelihood inside the mould wants the lock inside much setting, in order to make sure exact location and good side are propped up, prevent to bend with deflection.

Additional, tall rapid fire gives what rate increased a pattern to wear away, because this mould wants to use the tool steel of taller hardness, tall wear away, high erosive area (if runner is in) hardness should be more than HRC55.

(2) gating system: Shape thin wall goods, especially goods ply special hour, want to use big runner, and runner should be more than a wall thick.

So straight runner should install cold makings well, in order to reduce runner stress, assist fill, reduce the damage when goods purify runner.

Fill up to assure to have enough pressure thin modular antrum, pressure should decrease to fall as far as possible in flow path system.

For this, what flow path design wants to compare a tradition is a few bigger, want those who restrict fuse-element to be stationed in at the same time take time, in order to avoid colophony degradation deterioration.

Should be one model when much antrum, the requirement of the mould of convention of outclass of balance sex requirement of gating system.

Two advanced techniques still introduced in the gating system that notable is mould of thin wall goods, heat up flow path technology and runner of sequence valve type namely (SVG) technology.

(3) cooling system: Wall of tradition of unlike of thin wall goods is large can bear in that way bigger because conduct heat not all and the leftover stress of generation.

To assure the dimension stability of goods, control systole and warp inside the limits that can accept, with respect to the refrigeration that must strengthen a mould, ensure refrigeration is balanced.

Better cooling step has in model use inside core and modular antrum module do not close cooling line, increase cooling length, all can enhance cooling result, necessary place joins tall conductivity metal to set piece, conduct in order to accelerate heat.

(4) exhaust system: Bao Bi notes model to shape the mould needs to have good exhaust sex commonly, best and OK undertake vacuumize is operated.

Because fill time is short, inject rate is high, the sufficient exhaust of the mould flows especially the sufficient exhaust that forward position collects an area is very important, enrage ignition tiredly in case.

Gas is passed normally model the place eduction such as column of core, ejector pin, reinforcement, snail and cent face.

The extreme of flow path also wants sufficient exhaust.

Japanese Sumitomo company does small insert to solve the exhaust problem of small goods with poriferous tool steel.

(5) system of drawing of patterns: Because the wall of thin wall goods and muscle are very thin, damage very easily, and systole of edge ply direction is very small, make reinforcement and other small construction very easy agglutinate, astringe of high dwell pressure is smaller at the same time.

Be worn to avoid a top and sticking to mould, bao Bi notes model to shape should use note model to shape than convention the top with quantitative more, larger size goes out annul.

The groovy machine that note model is in very hard thin wall model the land that there is use force in noting model to shape.

The fill time that for instance Bao Bi notes model to shape is very short, time of a lot of fill is not worth 0.5s, speed-distance curve is abided by impossibly in so short time or cut off pressure, because this must use the microprocessor of high resolution control the machine that note model; In thin wall goods whole note model to shape in the process, answer to control pressure and rate independently severally at the same time, convention records model machine fill up level is controlled with speed, protect press level to turn again for pressure pilot method not applicable already.

So mechanical equipment manufacturer and research organization coact try hard, development gave appropriative inject device.

If Taiwan is medium,the VS-100 Bao Bi of company of aircraft of essence of life notes Dr of model machine, Germany. The Boy that Boy company develops series notes model machine and Battenfeld, Arburg and JSW to wait famous what the manufacturer develops the aircraft that note model is special the machine that note model.

Bao Bi notes model to expect into profile fluidity is close friends, must have length of big going from place to place.

Still have have high impact strength, high fever is out of shape temperature, good dimension stability.

Additional, the hear resistance that inspects data even, anti-flammability, machinery assembles gender and exterior quality to wait a moment.

Current, bao Bi notes model to shape wide the material that is application has polycarbonate (PC) , propylene nitrile, butadiene, styrene (ABS) reach PC/ABS to mix content to wait in all.

The fill procedure that technical convention notes model and cooling process interweave together, when polymer fuse-element flows, fuse-element forward position encounters opposite temperature inferior model core surface or model antrum wall, can form layer of a condensation in its surface, fuse-element continues to flow ahead inside condensation layer, the layer ply flow to polymer is having condensation to be affected significantly.

The property of the condensation layer in needing to note model to shape to Bao Bi has more thorough, more comprehensive research.

The numeric imitate that because this notes model about Bao Bi,shapes still needs to do a lot of works in the following respects.

(1) Bao Bi of more thorough and comprehensive research notes model to shape academic, especially the property of condensation layer, so that raise more reasonable hypothesis condition and attrib border requirement.

By afore-mentioned analysises knowable, model is noted to shape in Bao Bi in the process, its are very much condition and convention note model to shape have very big different.

When imitate, a lot of hypothesis of model of fuse-element flow maths and attrib border condition in Bao Bi the need in noting model to shape undertakes be adjustmented appropriately.

(2) note model to shape in Bao Bi certainly in increasing element, consider these factors correctly.

A few the negligible factor in model is noted in convention, often can flow to Bao Bicheng fuse-element the influence with larger generation.

For instance, in Bao Bi the viscosity in noting model has apparent dependence to pressure, and in convention in noting model to shape, do not have however; Frit wiring intensity is right model function impact is very big, especially thin wall model, frit wiring intensity and temperature and pressure are concerned, but the impact that pressure did not consider when groovy and numeric imitate; The specific heat of material, conduct heat coefficient and pressure loss.

Software of existing commercial numeric simulation because oversight these influencing factor, be in consequently forecast Bao Bi to note model to shape abhorrent phenomenon can appear when fill.

(3) the three-dimensional and numeric imitate with true application.

Having commercial numeric simulation software is to use 2 dimension, 2 dimension half element represents three-dimensional geometry figure simplify model, did not consider the physical quantity change on ply direction.

Three-dimensional flow area namely effect of fountain of front of area of change of turning point flow, ply, fuse-element is in existing numeric simulation software still cannot express, and they note model to shape in Bao Bi in have main effect.

(4) note model to shape whole process imitate.

Current simulation software basically includes fill, flow, protect pressure, cooling, wait for module with warp analysis, the development of each module is the mathematical model that is based on respective independence, oversight mutual the influence between.

But, from note model to shape in light of process, the flow full a pattern of plastic fuse-element, protect press and refrigeration is to interweave to be together and be affected each other, this notes model to shape in Bao Bi in particularly apparent.

Accordingly, flow full a pattern, protect pressure with cooling analysis and warp module must organic ground union rises, undertake coupling is analysed, comprehensive report notes ability actually model shapes.

(Editor: Green Hua Xiaoli)