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1、<p><b> 壓塑和壓鑄工藝</b></p><p> 近年,壓塑工藝應(yīng)用于熱固性摻混料,如脲醛塑料、酚醛樹(shù)脂、環(huán)氧樹(shù)脂、蜜胺樹(shù)脂和橡膠中。盡管有一些材料可注射成型,但采用壓塑工藝仍非常普遍。壓鑄用材料較壓塑用材料要求可塑性更軟。許多熱固性材料具有高抗沖級(jí)(1.0ft一lb)和良好缺口沖擊強(qiáng)度的保持性,只有在極限壓力下才會(huì)流動(dòng)。 </p><p>&
2、lt;b> 壓塑 </b></p><p> 熱固性材料的壓塑成型的明顯優(yōu)點(diǎn)是系統(tǒng)簡(jiǎn)單。將材料置入一加熱型腔,保壓至所要求團(tuán)化時(shí)間。因工藝過(guò)程簡(jiǎn)單,費(fèi)用少。添加劑和增強(qiáng)劑無(wú)規(guī)則,并能得到較好強(qiáng)度。由于無(wú)澆口和流道,不浪費(fèi)材料,模具幾乎也不用維修。零件的統(tǒng)一性好,無(wú)鑄口和流痕,減少了修飾成本。根據(jù)制品結(jié)構(gòu)和所用的塑料應(yīng)用特點(diǎn),可采用全壓式模具、半壓式模具和閉模(可參見(jiàn)有關(guān)壓塑模具方面的文章)。
3、 </p><p> 設(shè)備:簡(jiǎn)單也是壓塑設(shè)備的主要特點(diǎn)。兩半壓板結(jié)合在一起,加溫,加壓,將材料制成預(yù)定形狀。多數(shù)壓塑過(guò)程采用液壓操作;也有采用氣動(dòng)操作的。上下兩壓板在壓力之下在4個(gè)角柱上上下移動(dòng)。根據(jù)壓塑設(shè)備的大小,壓力一般為20—1000噸。壓板的大小一般為8英寸2到5英尺2. </p><p> 在加料和固化以后的脫模方面存在不同自動(dòng)化程度,常用最現(xiàn)代的液壓機(jī)進(jìn)行。以前的簡(jiǎn)單系統(tǒng)有
4、溫度控制、壓力控制、停壓控制和時(shí)間控制。現(xiàn)代設(shè)備采用更高級(jí)的微處理機(jī)控制。對(duì)于較薄的制品,在板中可用加熱筒或帶式加熱器。對(duì)較深的制件,需要用筒形電加熱器、蒸汽加熱或熱油系統(tǒng)加熱。有數(shù)種用于壓塑中的加熱體系:用蒸汽加熱模溫均勻,但加熱溫度限在350°F以下;套筒加熱或其它加熱(加熱盤(pán)管、加熱帶等)比較干凈,易于保養(yǎng),用得比較普及;熱油加熱,由于加熱介質(zhì)循環(huán)穩(wěn)定,所以加熱均勻?,F(xiàn)在又有許多新加熱方法,熱水加熱,類(lèi)似于熱油加熱,加熱
5、介質(zhì)一水一氣體燃燒連續(xù)循環(huán),可提供更高的壓塑溫度。 </p><p> 增強(qiáng)改性高分子材料工業(yè)發(fā)展迅速,要求壓塑工業(yè)有新改進(jìn)。模塑增強(qiáng)塑料用兩個(gè)模具:陽(yáng)模(模塞)和陰模(模腔)。當(dāng)模具充滿(mǎn)增強(qiáng)材料時(shí),對(duì)模的兩半熱模具閉合,然后加熱、加壓固化得到產(chǎn)品。相配合的模具復(fù)雜性變化很大,可用鋁、塑料或鋼制做。 </p><p> 輕質(zhì)材料制做起來(lái)比較便宜,一般用于短期生產(chǎn)如“冷模塑”。冷模塑用室
6、溫固化樹(shù)脂,但仍使用模具和壓塑液壓機(jī)。長(zhǎng)期生產(chǎn)用硬化鋼模具比較合算,對(duì)截坯口可提供較好的剪切性能和優(yōu)良的光潔度。這些壓塑鋼模采用機(jī)械上適配的截坯口,通常面對(duì)合模區(qū)。用這種對(duì)模的金屬模具,其制品表面均勻,光潔度好。閉模工藝用于壓塑成型、壓鑄成型、注射成型及一些可沖壓的增強(qiáng)復(fù)合材料。 </p><p> 一些熱塑材塑料可壓塑模塑,但一般還是用預(yù)摻混的熱固性樹(shù)脂如BMC(預(yù)制整體模塑料)、SMC(片料成型模塑料)、T
7、MC(厚模塑料)、氈片成型等。 </p><p> 氈片成型有時(shí)叫濕成型復(fù)合材料,在液壓機(jī)的作用下將增強(qiáng)材料和樹(shù)脂結(jié)合在一起。經(jīng)常在模中放置氈片,將樹(shù)脂傾倒在加強(qiáng)材料上。在加壓過(guò)程中樹(shù)脂充滿(mǎn)模腔時(shí)加強(qiáng)材料固定不動(dòng)。 </p><p> 若制件有嚴(yán)重的異形或斜度,有必要進(jìn)行預(yù)成型。多數(shù)氈片和預(yù)成型制州在投影面積上需要加150—200磅/英寸2的模壓力。 </p><p
8、> 預(yù)摻混料,如SMC,預(yù)浸樹(shù)脂,填料、催化劑和增強(qiáng)料切割成一定大小隊(duì)片狀,再加入熱的模具中(一般300—400°F),在1000~2000磅/英寸2壓力下模塑。 </p><p> 用于SMC的較新的壓塑設(shè)備的總循環(huán)周期可少于一分鐘(從頭到尾)。已經(jīng)發(fā)展了用特殊的液壓裝置推回壓塑機(jī)中料筒,自動(dòng)控制壓板的水平度。 </p><p> 增強(qiáng)塑料,如SMC,用金屬對(duì)模壓塑
9、光潔度好,這對(duì)制件的表面很重要。在加工時(shí)有時(shí)出現(xiàn)纖維狀的收縮。 </p><p> 用內(nèi)模涂層的方法可改進(jìn)表面光潔度。BMC的壓塑過(guò)程是最老的預(yù)摻混后的模塑過(guò)程之一。 </p><p> 填料(木屑、礦物料、纖維素等)的摻混混合是在葉片形的混合器中進(jìn)行的。將一批料裝入300~400°F的模具中.在500磅/英寸2壓力下模塑。因用料廉價(jià),所以原料成本低。不過(guò)由于在模塑過(guò)程中纖維
10、的定向性降低了機(jī)械強(qiáng)度。 </p><p> 高速壓塑,即增強(qiáng)熱塑性塑料片材的沖壓,用途廣泛。玻璃氈片和聚丙烯相配合用于可沖壓的塑料,其循環(huán)周期低于40秒。生坯送至對(duì)流爐中加熱。加熱以后,毛坯放入壓塑模具中,這一過(guò)程用新的壓塑機(jī)速度可達(dá)1400英寸/分鐘。以75英寸/分鐘(比SMC的壓塑過(guò)程快約3倍)加壓進(jìn)料。根據(jù)市場(chǎng)的要求,有些新的可沖壓塑料,表面光潔度好,并且具有可涂布性。模塑壓力一般1噸/英寸2。傳統(tǒng)的壓
11、塑工藝近幾年一直呈增長(zhǎng)的趨勢(shì)。在空間技術(shù)和國(guó)防方面的應(yīng)用正在使這種工藝向其難點(diǎn)沖擊。 </p><p> 在SMC、BMC、TMC、熱塑性片材的沖壓、增強(qiáng)材料的摻混和壓塑機(jī)械方面的發(fā)展迅速增長(zhǎng),以適應(yīng)工業(yè)的新要求。 </p><p> 一些先進(jìn)的摻混料的壓塑主要是在空間技術(shù)和國(guó)防應(yīng)用方面發(fā)展迅速。工具和模具的新概念及高溫(達(dá)1200°F)模塑機(jī),使石墨一碳纖維復(fù)合材料得以發(fā)展
12、,代替了現(xiàn)有的金屬鑄件。 </p><p> 高溫硅樹(shù)脂正用作高壓介質(zhì)。復(fù)合材料做的片層用于壓塑模中?,F(xiàn)在,材料和生產(chǎn)成本已使該工藝更加適于空間技術(shù)市場(chǎng),這類(lèi)硅樹(shù)脂也很快轉(zhuǎn)向汽車(chē)領(lǐng)域。 </p><p><b> 壓鑄 </b></p><p> 在壓鑄工藝中,熱固性樹(shù)脂料加入一單獨(dú)的料腔,常叫料槽,然后強(qiáng)制送入一個(gè)或多個(gè)閉模中進(jìn)行聚合(
13、固化)。 </p><p> 料道,也叫注道和流道,使物料從料槽流向模腔,進(jìn)入模腔之前經(jīng)過(guò)限流器或澆口。很多模腔具有單一料槽。料腔中的空氣被進(jìn)來(lái)的物料所置換,并通過(guò)一特別放置的排氣口排出。 </p><p> 當(dāng)物料置入料槽中時(shí),在一緊湊的測(cè)量裝置中測(cè)料量,然后預(yù)熱到接近聚合溫度。一次只加入足夠一次的注塑量。 </p><p> 將預(yù)熱的原料送出料槽的力再將其
14、送往一注料器,該注料器緊接裝在料槽上,以防止從活塞和料槽邊之間的縫隙中漏料。通常將密封套卡進(jìn)注料器以進(jìn)一步防漏。 </p><p> 料槽、注料器、澆口、流道和模腔的表面維持可使原料迅速固化的一定溫度,根據(jù)物料性質(zhì)、模具的設(shè)計(jì)和制件的幾何形狀該溫度為280~380°F。 </p><p> 在壓鑄物達(dá)到固化期的終點(diǎn)時(shí),將該次完整的壓鑄物進(jìn)行脫模,包括脫除澆口、流道、注道和料槽
15、中形成固化料墊(叫做殘料)。 </p><p> 在壓鑄中,物料的預(yù)熱很重要。冷料流動(dòng)緩慢,先進(jìn)入模腔的料尚未到其終點(diǎn),即可能聚合。若發(fā)生上述情況,產(chǎn)品質(zhì)量低劣,不僅是外觀,也體現(xiàn)于機(jī)械性能。有些例外,如一次注射量很少,或一些低粘度的物料??捎眉訜釤艋驙t子加熱,但有效而常用的方法是用專(zhuān)為塑料模塑制做的介電加熱器。</p><p> Plastic and pressure die ca
16、sting process</p><p> In recent years, the pressure technique used in thermosetting plastic material</p><p> mixing ,such as urea-formaldehyde plastics, phenolic resin, epoxy rsin, melamine<
17、;/p><p> resin and rubber. In spite of some of the material can be injection moiding, but the use of plastic pressure process is still very common. More pressure die casting material used plastic materials
18、 require more malleable soft. Many thermosetting materials with high impact level (1.0ft-1b) and good impact strength of maintaining the gap, only under ertreme pressure will flow.</p><p> Thermosetting p
19、lastic molding material pressure of the obvious advantages of the system is simple. Materials will be placed in a heating cavity, the pressure required by the Mission to time. As a result of the process simple, cost less
20、. Enhancer and additive-free rules, and be able to get a better strength. As the gate and no runner ,not a waste of materials, die almost no maintenance. Parts of unity, and I cast no trace flow and reduce the cost of th
21、e modification. According to the structur</p><p> Equipment: The pressure is a simple plastic deices the main features . platen combination of the two and a half , heating, pressure, the shape of the ta
22、rget material. Most of the process of plastic used hydraulic pressure to operate; also used pneumatic operation .Tow board up and down under pressure in the 4 corner posts on moving up and down. According to the plastic
23、device the size of the pressure, the pressure is generally 20-1000 tons. The general board for the 8-inch size 2-5 feet 2.</p><p> In addition, and after curing the release of different aspects of the degre
24、e of automation, the most commonly used modern hydraulic machine. The previous system , there is a simple temperature control, pressure control, pressure control and stop-time control. The use of modern equipment, advanc
25、ed microprocessor control. For thinner products, in the board can be used in heating tube or belt heater. To the deeper parts, the need to use tube-shaped electric heater , heating steam or hot oil heating</p><
26、;p> Polymer modified to enhance rapid industrial development requires a new pressure to improve the plastic industry . Enhanced by two molded plastic mold: mold-yang (side mode) and the negative mold (cavity). W
27、hen the mold is full of reinforcements, the mode of the hot mold closed two and a half, and then heated, pressurized product to be cured. Along the lines of big changes in the complexity of the mold can be used aluminu
28、m, plastic or steel do.</p><p> Light-weight materials making them less expensive, generally used for the production of short-term such as “cold-molding”.Coll at room temperature with molded resin, but the
29、use of plastic mold and hydraulic pressure. The production of long-term use of hardened steel molds relatively cost-effective, the cut-off billet I can provide better performance and excellent cut finish. These steel pr
30、essure module on the use of machinery on the cut-off billet adapter I usually die together in the face ar</p><p> Some of the thermoplastic plastic materials can be molded plastic pressure, but in general
31、or with pre-mixing of thermosetting resins such as BMC (prefabricated molding as a whole),SMC(film forming material molding),TMC(thick molding),film forming, such as carpet.</p><p> Carpet wet film forming
32、sometimes called composite molding, in the hydraulic press will strengthen the role of materials and combined with resin. Often placed in the mold in carpet film will be dumped in to strengthen the resin material. Pressu
33、re in the process of cavity filled with resin to strengthen the material when fixed.</p><p> If there are serious parts of the alien or gradient, it is necessary to carry out pre-forming. Most of the film a
34、nd felt pre-forming system in the projected area of the state’s need to 150-200 pounds/2 inch of mold pressure.</p><p> Pre-mixing materials, such as SMC, prepreg resin, filler, and the catalyst size enha
35、nce the material cut into a certain team sheet, and then adding the hot mold (in general 300-400 F), 1000-2000 1b/2 inch pressure Under the molding.</p><p> SMC for the relatively new plastic devices the pr
36、essure of the total cycle may be less than one minute (from start to finish). Has developed a special hydraulic device back in the bowl pressure machine, automatic control of the board level degrees.</p><p>
37、; Reinforced plastics, such as SMC, with a metal finish on molded plastic, tjis is very important parts of the surface. Sometimes occur in the processing of fibrous contraction.</p><p> Model with coating
38、method could improve the surface finish. BMC pressure of the process of plastic is the oldest pre-mixing after one of the molding process. Filling materials (wood, mineral materials, such as celluiose) are mixed in mixin
39、g the leaves in the shap of the mixer. Will feed into a group of 300~400 F in the mold. In the 500-pound/2 inches under the pressure of molding. As a result of the use of materials for low-cost, the cost of raw mater
40、ials. However, as in the molding process,</p><p> Plastic high-speed pressure, that is, enhanced thermoplastic stamping the sheet, a wide range of uses. Felt piece of glass and polypropylene can be used to
41、match the plastic stamping, the cycle less than 40 seconds. Green sent to the convection heating furnace. Heating, rough pressure into plastic molds, in the process with new pressure machine machine speed up to 1400 in
42、ches/minute. To 75 inches/minute (SMC than the pressure of plastic process about 3 times as fast) feed pressure. According t</p><p> In the SMC, BMC, TMC, the thermoplastic sheet stamping, reinforcement of
43、the Blending plastic mechanical pressure and the development of the rapid growth of industry in order to meet the new requirements.</p><p> A number of advanced materials mixing plastic pressure mainly in s
44、pace technology and applications in the rapid development of national defense. Tools and dies and the new concept of high-temperature (up to 1200 F) molding machine to make a graphite carbon fiber composite materials c
45、an be developed to replace the existing metal castings.</p><p> High temperature silicone is used as a high-pressure media. The composite sheet for the pressure in the mold. Now ,materials and production co
46、sts have made the process more suitable for space technology market, this type of silicone is also soon to the area of automobile.</p><p> In the die-casting process, thermosetting resin material is expecte
47、d to join a separate chamber, often called trough, and then forced into one or more closed modules for polymerization(curing).</p><p> Liu, also known as Notes and the road runner, so that the flow of mater
48、ials from the through cavity into the mold cavity before or after limiting gate. Many cavity with a single through. The air chamber is expected to be the replacement materials come in through a special place of the exhau
49、st emissions.</p><p> When the materials placed in the trough, in a compact measuring device detected charge, and then warm-up to close to the polymerization temperature. Only by adding a sufficient amount
50、of time the injection.</p><p> Preheat the raw materials will be sent trough of force and then a note sent to the feeder, the feeder note immediately installed in the trough, so as to prevent the pistons fr
51、om the trough and gap between the edge of missing material. Taoka is usually closed to inject into the feeder to further leak-proof.</p><p> Trough, the note feeder, gate, runner and mold cavity on the surf
52、ace of the material can maintain the rapid solidification of a certain temperature,according to the nature of the materials, mold design and parts of the temperature of 280~380 F.</p><p> In the die-casting
53、 material to reach the end of the curing period, the second-casting for a complete release, including the removal gate, runner and injecting Road in trough and the formation of curing pad material (called salvage).</p
54、><p> In the die-casting, the warm-up material is very important. Cold expected to sloe the flow, first into the cavity of the material to its destination yet, that is likely to polymerization. If it happens,
55、 poor product quality, not just the appearance, but also in mechanical properties. Some exceptions, such as injecting a small amount, or some of the low viscosity of the material. Available light or heating stove heating
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