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沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 摘要
摘要
聚氨酯全稱為聚氨基甲酸酯 ,是主鏈上含有重復(fù)氨基甲酸酯基團(tuán)的大分子化合物的統(tǒng)稱。它是由有機(jī)二異氰酸酯或多異氰酸酯與二羥基或多羥基化合物加聚而成。聚氨酯大分子中除了氨基甲酸酯外 ,還可含有醚、酯、脲、縮二脲 ,脲基甲酸酯等基團(tuán)。
聚氨酯成型機(jī)是通過(guò)對(duì)聚氨酯加熱到熔融狀態(tài)，再靠離心機(jī)的離心原理將熔融的聚氨酯輸送到攪拌頭。經(jīng)過(guò)高速?gòu)?qiáng)烈攪拌，使之料液均勻而噴出，形成所需產(chǎn)品。而離心成型技術(shù)是利用離心力成型管狀或空心筒狀制品的方法。通過(guò)擠出機(jī)或?qū)Ｓ寐┒穼⒍康囊簯B(tài)樹(shù)脂或樹(shù)脂分散體注入旋轉(zhuǎn)并加熱的容器(即模具)中，使其繞單軸高速旋轉(zhuǎn)(每分鐘幾十轉(zhuǎn)到兩千轉(zhuǎn))，此時(shí)放入的物料即被離心力迫使分布在模具的近壁部位。在旋轉(zhuǎn)的同時(shí)，放入的物料發(fā)生固化，隨后視需要經(jīng)過(guò)冷卻或后處理即能取得制品。在成型增強(qiáng)塑料制品時(shí)還可同時(shí)加入增強(qiáng)性的填料。離心澆鑄通常用的都是熔體粘度較小、熱穩(wěn)定性較好的熱塑性塑料，如聚酰胺、聚乙烯、聚氨酯等。
離心成型時(shí)，聚氨酯填充模具型腔主要靠的是離心機(jī)旋轉(zhuǎn)時(shí)產(chǎn)生的離心力。離心力與質(zhì)量成正比，與離心機(jī)轉(zhuǎn)速的平方成正比，與旋轉(zhuǎn)半徑成正比。因此，對(duì)某一規(guī)格的轉(zhuǎn)子而言，聚氨酯的質(zhì)量和旋轉(zhuǎn)半徑是一定的，所以離心力的大小僅與離心機(jī)的轉(zhuǎn)速有關(guān)，增大或減少離心力，只須改變離心機(jī)的轉(zhuǎn)速即可。
在離心成型時(shí)，聚氨酯除了受到自身的重力作用外，主要是靠離心力的作用來(lái)填充模具型腔的，其填充方式是先填充遠(yuǎn)離旋轉(zhuǎn)中心的型腔的外部，然后逐漸向心部填充完畢。因有離心力的存在，且它比重力大得多，所以聚氨酯的填充能力要比重力成型時(shí)強(qiáng)，只要離心機(jī)轉(zhuǎn)速適當(dāng)，離心力的大小合適，生產(chǎn)出的轉(zhuǎn)子的質(zhì)量就一定比澆注成型時(shí)形成的轉(zhuǎn)子要好得多。
關(guān)鍵詞：聚氨酯；離心成型；滾筒
Abstract
Polyurethane full-called polyurethane, is the main chain contains repeating urethane groups of molecules, collectively. It is an organic diisocyanate or polyisocyanate or polyol with two hydroxyl addition polymerization is made. Polyurethane macromolecules in addition to urethane, it can also contain ether, ester, urea, biuret, urea-based groups such as ester.
Polyurethane polyurethane molding machine is heated to melt through the state to rely on the principle of centrifuge centrifuge transported to the melting of the polyurethane mixing head. After strong stirring speed, so that even the spray liquid, to form the desired product. The centrifugal molding technology is the use of centrifugal force forming tubular or hollow tubular products method.Through the extruder hopper or dedicated to quantitative liquid resin or resin dispersion into the rotation and heating container (ie, mold), making it rotate around the axis high-speed (tens of per minute to two thousand rpm), then put incurs centrifugal force into the material distributed in the mold wall parts. Rotating at the same time, into the material cures, and then as needed through the cooling or post-processing that is able to obtain products. Enhanced the molding plastic products can also added to enhance the nature of filler. Centrifugal casting melt viscosity are usually smaller, better thermal stability of thermoplastics such as polyamide, polyethylene, polyurethane, etc.
Centrifugal molding, polyurethane fill the mold cavity is the main centrifuge rotation by the centrifugal force generated. Centrifugal force is proportional with the quality, speed proportional to the square with the centrifuge, and the radius is proportional to. Therefore, a specification of the rotor, the polyurethane is a certain quality and radius, so the size of the centrifugal force only with the speed of the centrifuge, increase or reduce the centrifugal force, centrifuge speed can only change.
In centrifugal molding, polyurethane except by their own gravity, the centrifugal force depends mainly on the role to fill the mold cavity, the fill mode is first filling away from the center of rotation of the external cavity, and then gradually to the heart of the Department of Tianchong completed . Due to the presence of centrifugal force, gravity force and it is much larger, so the polyurethane molding filling capacity than gravity is strong, as long as the appropriate centrifuge speed, the centrifugal force of the right size to produce the quality of the rotor must be better than pouring molding form The rotor is much better.
Key words: polyurethane; centrifugal molding; drum