Polyurethane聚氨酯的浇注工艺

1、Chapter 3弟二扁Mixing and Casting Polyurethane搅拌和聚氨酯的浇注This chapter is divided into two parts:Basic mixing and casting Background to mixing and casting 这一篇分为两部分：搅拌和浇注的基本知 识；搅拌和浇注的背景。The first part covers the steps and equipment required for making a polyurethane part; the second covers more detailed as

2、pects of the process.第一部分涵盖了制造聚氨酯件的步骤和设备要求，第二 部分涵盖了聚氨酯工艺的更多的细节方面的内容。3.1Basic Mixing and Casting搅拌和浇注的基本知识There are two basic ways to mix polyurethane:Machine processingManually这里有两个基本的搅拌聚氨酯的方法：机器搅拌工艺和人工操作。Note: Before any handling of polyurethane chemicals or equipment, all staff and makers must be

3、familiar with the occupational Health and Safety requirements for the use of chemicals and machinery as well as all local rules and regulati ons. Copies of the releva nt Material Safety Data Sheets(MSDSs)must be studied and adhered to. Chapter 14 discusses the subject of health and safety in more de

4、tail.注意：在进行聚氨酯的化学试剂或设备的使用前， 所有的员工及生产商必须对使用这些 化学制品及设备像了解本地政策及习俗一样的熟悉。相尖的材料的安全成分表的复印件必须拿来学习 并坚持遵守。第14篇就是对健康和安全这一课题的详细讨论。3.1.1Machining Processing机械制造工艺Machine processing should be carried out using the initial setting given by the raw material and the machine manufacturers. Both the machine and the ma

5、chine system must be compatible with each other and capable of allowing fine adjustments.机械的制造工艺应该通过采用聚氨酯原材料商和设备制造商提供的最初设置来进行实施。这些设 备和设备系统必须彼此互相兼容且有很周密的调整适应功能。The machine must be large eno ugh for the producti on to be completed without a full shutdow n and recharge of the system.这个机器设备必须足够大，使得产品在生产

6、过程中不能没有一个完整的断电再充电系统。Machine casting is ideal for one-shot processes where all the ingredients are mixed in a multi- input machine. Some of the ingredients may be preblended，such as the polyols, catalysts, andextenders.机械浇注对于一次浇注成型的工艺来说是可行的，所有的配料都被混合在一个多端输入的机器 中。有些配料需要被预混合，像聚氨酯，催化剂以及填充剂。3.1.2Manually

7、 人工操作Basic equipment基础设方伍Safety gloves, mask, and goggles安全手套，防毒面具以及护目镜Molds模具-Ovens烤箱Microwave oven 微波炉SCaleS电子称-Devacuuming system 抽真空系统-Dry nitrogen Supply 下氮气供应Mixing Container 搅拌锅Stirring paddleS 搅拌桨-Melting potS for Solid CurativeS(if required)加热固体激活剂的加热罐Bonding agents粘结力测试工具Butane burner 丁烷燃烧

8、炉Trimming kniveS修整用的刀具-MaChining equipment(if required)机器设备(如果需要)MeaSuring and teSt equipment(aS required)测量及检测设备(如果需要)BaSiC Materials 基本 原料PrepolymerS预聚物-Curatives 激活剂-Alternative quaSiprepolymer SyStem可供选择的预聚化物系统Mold releaSe 脱模剂Pigments颜料Fillers填充剂-PlaStiCiZerS增塑剂(塑料桶?)-Cleaning Solvents干净的清洁试剂3.1

9、.2.1Method 方法The molding procedure iS a multiStep proCeSS with Several StepS running in parallel.这个注模 过程是一个有多种步骤同时进行的复合工艺。1.Preparation 准备a.Clean and bring molds to temperature清理模具并预热模具到一定温度 Make any repairs 修理完毕Clean SurfaCe dirt清理掉表面的灰尘 Remove old mold buildup if neCeSSaryHeat to Curing temperatur

10、e 加热到固化温度b.Thaw prepolymers已溶解的聚氨酯Keep in warm parts of Shop在工厂中保持它的温度Under oven置于烤箱中Polytetramethylene glycol( PTMEG) based Prone to solidify 聚丁二醇倾向于固化 No Center milk in ess中心没有乳状浑浊Roll mix to elimi nate temperature VariatiO ns 摇晃搅拌时减少温度变化c.Melt CUratiVe if necessary加热激活剂使融化如果需要的话Do nOtoVerheat不要过热

11、 Only Sufficient for day仅够1天足量的即可d.Weigh out prepolymer and CUratiVe 称量预聚物和激活剂Into clean dry Container彻底清理干净装的容器MaXimUm depth 25% of height最大深度是总深度的25%Can We USe more than OneContainer for large pours 大的浇注可以使用 1 个以上的 容器e.Bring to COrreCt temperature 调到合适的温度Bring to SUPPIier recommended temperature 调

12、至 U 供应商建议的温度USe microwave for smaller amou nt可使用微波炉来加热较小的量f.DegaS 脱气USe VaCUUm pot使用真空罐APPrOXimately 6KPa(28nHg)VaCUUm 真空压强在 6Kpa(28HHg) Break VaCUUm if too foamy如果太多的气泡需要停止抽真空2.MiXing 搅拌a.Add Pigme nt to prepolymer将颜料添加到聚氨酯中Some Pigments need to be PrediSPerSed into the prepolymer 有些颜料需要提前力l至I 聚氨酯中

13、分散幵b.Add CUratiVe to prepolymer in ge ntle Stream 将激活剂缓缓加入到聚氨酯中 Add to mixing Container in a Stream连续不断的将激活剂加到搅拌的容器Pour along one edge 沿着一个边倾倒c.MiX USing ZigZag motion or CrOSS-blending使用曲折的动作曲线来交错双向搅拌Do not WhiP in air不要在空气中搅拌Clea n prepolymer from edges and corners into mix 聚氨酯的边边角角都要进行搅 拌Clear mi

14、xes must be Streak free 搅拌器要清理干净Pigments must be completely dispersed颜料必须完全地在聚氨酯中扩散开d.DegaS again再次脱气If required degas aga in PrOVided there is SUffiCie nt pot life 倘若在有效的适用期内 要 求再次脱气3.Pouring 浇注a.Add to mold in thin Stream将原料成细股状浇入模具中Rate of pouri ng must n Ot block in let in mold浇注时不能大股地注入到模具中 In

15、CreaSe height to PreVe nt blockage duri ng pouri ng 在浇注过程中逐渐地增加高度 来防止浇注过程中的中断b.Polyuretha ne must flow dow n mold and displace air UPWard 聚氨酯必须流入模具flash with knife or by grinding用刀子将飞溅割掉或通过打Clean item清理项中并使得空气往上排出Mold fill should be from bottom up.模具的浇注需从底部往上面来浇满All SUrfaCeS must be Wetted With no a

16、dheri ng air bubbles.所有的覆膜面都不能有 气泡附着在表面。c.Air must not be trapped in mold 空气绝对不能残留在模具中 Mold must be titled and/or rotated for undercuts to be completely filledd.Polyurethane should not fold on itself 聚氨酯不能靠自己来混合 Polyurethane that is gelling can fold over on itself and cause fault linese.Pouring must

17、 be completed in time for air bubbles to escape before material gels 浇 注 要及时完成，因为要在材料固化之前使材料中的气泡跑出Gel point can be determined by drawing a thread from surface, using piece of wire with diameter of a paper clipUse a soft” butane flame to pop surface bubbles用较柔的丁烷火焰将件表面的气 泡 燃烧掉Always keep flame moving

18、要一直让火焰不断移动4.Curing 固化a.Place filled mold in oven 将注满的模具放入烤箱 Oven set to approximately 10 C higher than initial mix material temperature烤箱 设置到比原料混合搅拌时的温度高10 CPolyurethane must be not heat up or cool mold聚氨酯不能温度太高或模具的温 度太低b.Demold when part have sufficient strength当零件有足够的强度时可以进行脱模Normally 1 to 2 hours

19、 (See suppliers recommendation)通常是 1 至！J 2 小时(详见供 应 商的建议)MDI-based systems may be hard but still brittlec.Remove any major flash and sprues除去任何主要的浇注飞溅和浇注口结渣Use sharp knife使用锋利的刀子Material not as tough as when fully cured 材料不如充分固化后坚硬d.Prepare mold for next pour 为下一次的浇注准备模具 Recoat mold with mold releas

20、e 重 新在模具上j余上月兑模齐This is not always necessary as often more than one casting can be made这个操作 不需要经常进行因为不止进行一次浇注Keep hot for next run为下一 轮的浇注保持温度5.Post curing 后固化a.Return part to oven for 8 to 18 hours for full将件重新放入烤箱进行818小时的 充分固 化Follow supplier recommendations for time and temperature根据供应商的要求来 设定时间及

21、温度Cycle is normally overnight 一个循环一般是一整晚Very hard materials need extra postcure to overcome brittleness 很硬的件需要额夕卜 的后 固化来克服脆性b.Final cleaning of flash lines and sprues 最后的飞溅的清理和浇注熔渣 Remove extrac.Any postmolding machining 脱模后的机加工 Machine dimension to size 机加工到要求尺 寸 Remember thermal expansion 注意受热膨胀3.

22、2Background to Mixing and Casting搅拌和浇注的基础3.2.1Introduction 说明The mixing of polyurethane components is to complete chemical reactions that convert the various ingredients to viable products with known properties. There are four main points that must be adhered to:聚氨酯成分的搅拌是完成将化学反应转化成各种我们需要的性能的产品材料。这里有

23、必须坚持的 四点内容：Everything dry and keep dry after use(see 3.2.1.1)在完成使用后所有的东西要保持干燥(详见3.2.1.1 )Correct weights of all ingredients所有的配料称量要准确Correct temperatures of ingredients, molds and curing temperatures and times 酉己料温度，模具温度以 及固化温度和时间要正确Correct mixing and casting techniques 正确的搅拌和浇注技巧These are the basic

24、 requirements to produce satisfactory products 这些是工厂生产岀合格产品的基本 要求。3.2.1.1 Dryness of System 系统的干燥Raw materials are no rmally supplied with moisture con tent of less than 0.05%. The prese nee of moisture in the system will result in fine bubbles throughout the entire pour. These bubbles are very smal

25、l and evenly dispersed. Included air bubbles are larger and more randomly dispersed.原材料通常 提供时含水量低于0.05%.含水量的多少在整个浇注系统中会导致气泡的产生。这些通常气泡比较小 且均匀分布。也不包含比较大而且不均匀分布的气泡。All containers must be flushed with dry nitrogen gas prior to resealing after use .Normal commercial compressed nitrogen is dry enough with

26、 a dew point of at least -40 C.在使用过后这些的容器要提前 用干氮填平进行再次密封。通常商业用的压缩氮气是足够干燥的且露点至少在-40 C。Some curatives such as BDO are very hygroscopic and must be han died with care to prevent the absorption of any moisture.有些激活剂像二醇容易吸湿并且必须要很小心地保护防止吸收到任何的 水分。3.2.2Basic Requirements 基本要求3.2.2.1 Molds 模具Molds for casti

27、ng polyurethane parts can be made from a wide range of materials. The most important factor is that they must be impervious to moisture and not contain any moisture. The other main criterion is that they must not be thermoplastic at the processing temperature. Some of the main materials used to make

28、 molds include the following：浇注聚氨酯的模具可以由多种的材料做成。最重 要的表现是它们不受潮湿的影响不会吸收水分。另一个主要的标准是在工艺过程的升温中不能是热塑 性的。制作模具的主要原料一般包括以下的几种：Polyurethane聚氨酯Aluminum 铝Epoxy (filled and unfilled)环氧树脂(填充的或未填充的)Silicones (either encased or backed )硅胶 Steel 钢Hard thermoplastics硬的热性塑料Polyester resins 聚酯树脂PolyUrethanes, silicOne

29、s, and epoxies are Very USefUl for making molds Of ObjeCtS that need to be reproduced.聚氨酯，硅胶和环氧树脂对于需要重新制作产品模具的是非常有用的材料。Molds must be cost effective. A mold may be made in a Single PieCe or in any number of Parts With or WithOUt inserts. The following are some main factors to be Considered in making

30、a mold:模具的成 本要非常划算。一个模具可以是单独的一件整体或者是由若干数量的带金属或不带金属的零件构成。 下面是制作模具应该要考虑到的主要方面：Value of Part bei ng made被制作的件的价值NUmber of Parts to be PrOdUCed要生产的产品的数量Finish of Part产品的完成数量ACCUraCy of SiZe of finished Casting完成的铸件的尺寸的精确度POSitiOnSandnature of any undercuts任何的咬边的位置和特点SiZe and ShaPe of in SertS金属件的尺寸和形状An

31、y holes in molding模具中的任何孔POSitiO ns allowable for pour holes and vents浇注允许的浇注孔或排气孔的位置Available pot life of polyuretha ne 聚氨酯的有效使用期Polyuretha ne Shrinks any Where betwee n 0% and 2% on CUring depe nding on the grade and the CUre circle. Room temperature CUre Can have zero Shri nkage. The no rmal rang

32、e of Shri nkage is 1%to1.5%.聚氨酯在固化过程中，任何地方的收缩率根据级别和固化周期的不同在0%到2%之间。在室温情况下固化收缩率为0.正常的收缩范围是1 %到1.5%。Shrinkage is three dimensional. The amount in thin SeCtiOnS may not always be noticeable.收缩是立体的。在比较薄的件上收缩并不是很明显。3.2.2.2DeSign FaCtorS 设计因素The follow ing are some Points that should be take n into acco U

33、nt Whe n desig n a mold:下面是在设计模具时应该考虑在内的几点：Allow a Slight draw on long Parts to allow for removal if POSSible-1/2to 1。可以允许在长点的件上有1/2到1 的斜度从而方便从模具中拔出。Undercuts Cannot be pulled out切入的不易被拉出来Visible areas are best from molded SUrfaCeS从模具面上得到的可视区是最好的If the Shrinkage of the SyStem is Un Certain, make the

34、 mold on the smaller limits. If Part is too small, material Can no rmally be removed from the mold.如果这个系统的收缩率不确定，要将模具做到小公差。如果零件太小，材料通常是可以从模具中取出的。-Adding material to the mold is expensive.向模具中添加原料是很昂贵的。For molds in two halves pour One half, cure, mold, release, and the n pour the SeC Ond half.Molds W

35、ith an Undercut-make Vertical Casting slit into two Vertical halves With SCalPel or other thin, SharP knife. Make tight-fitting outer mold to keep the two halves together.因为模具要用来浇两个半片的件，需要先浇注1半，预热，装模，脱模然后再浇注另一半。More details are give n in ChaPter 5.在第5部分会给出更多的细节。3.2.2.3 EqUiPment 设备The SiZe and complexity Of the equipme nt n eeded depe nd On the n ature Of the PrOdUCtS being produced.根据生产的产品特性来决定需要的设备的规格及复杂程度。Weighing equipment 称量设备-EleCtrOniC SCaleS are the most commonly USed 电子称是最常用的The Weight range to SUit Weigh ing prepolymer for hand PrOCeSS ing is 5 to 30 kg maximum in at least 1 gr