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3) 2020 АнДУ
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- SPECIAL INJECTION MOLDINGPROCESSES OF POLYMERS K.A.Makhammadjanov - assistant, K.A.Kamolov - student, A.Sh. Isomiddinov – student, M.L.Atabaev – student.
ADABIYOT 1. Парпиев О.А., Солиев Б.А. Танлов фани сифатида―амалий бионикага кириш фанини ўқув жараёнига киритиш. Машинасозлик илмий хабарномаси № 1, Андижон, 2019. 14-18 бетлар. 2. Парпиев О.А., Аббосов Х.А., Мамадалиев Ш.У. Архитектурада бионикадан фойдаланиш истиқболлари. Машинасозлик илмий хабарномаси № 4. Андижон, 2018. 90-97 бетлар. 3. Брайнес С. Н., Свечинский В. Б., Проблемы нейрокибернетики и нейробионики, М., 1968: 4. Бионический конструктор Эльпюль. // Биомолекула. URL: https: //biomolecula.ru/articles/bionicheskii-konstruktor-elpiul (дата обращения 12.01.2018) 5. Гиндоян, А.Г. Вопросы обследования технического состояния зданий и сооружений. Промышленное и гражданское строительство. -М., 2006. -№ 2. -С. 21-22. SPECIAL INJECTION MOLDINGPROCESSES OF POLYMERS K.A.Makhammadjanov - assistant, K.A.Kamolov - student, A.Sh. Isomiddinov – student, M.L.Atabaev – student. Andijan Machine-building institute There are several variations of injection molding processes, many of which are still under development. Furthermore, due to the diversified nature of these special injection molding processes, there is no unique method to categorize them. Fig.1. attempts to schematically categorize 50 special injection molding processes for thermoplastics. The most common special injection molding processes are multi-component injection molding, co-injection molding, gas assisted injection molding, injection-compression molding, reaction injection molding, and injection molding of liquid silicone rubber. Figure 1.Schematic classification of special injection molding processes for thermoplastics. Multi-component (or multi-color) injection molding is used to inject two or more components through di fferent runner and gate systems at different stages during the molding process. Each component is injected using its own plasticating unit. The molds are often located on a turntable. Multi-color automotive stop lights are molded this way. In multi-component processes, often two incompatible materials are molded or one component is cooled su fficiently so that the two components do not adhere to each other. For example, to mold a ball and socket system, either the ball or the socket of the linkage is molded first. The component that is injected first is allowed to cool somewhat before the second component is molded in. This results in a perfectly movable system; if the socket is injected first, the assembly will be loose and if the ball is molded first, the assembly will be tight, as the socket shrinks over the ball. This type of injection molding process is used to replace tedious assembling tasks and is becoming popular in countries where labor costs are high. Hence, this type of process is referred to as assembly injection molding. A commonly used method of multi-component injection molding employs a rotating mold and multiple injection units, as shown in Fig.2. Once the insert is molded, a hydraulic or electric servo drive rotates the core and the part by 180 degrees (or 120 degrees for a three-shot part), allowing alternating polymers to be injected. This is the fastest and most common method because two or more parts can be molded in every cycle. Another variation of multi-component injection molding cores or slides while the insert is still in the mold. This process is called core - pull or core-back, as shown in Fig. 3. To be specific, the core retracts after the insert has solidified to create open volume to be filled by the second material within the same mold.[1]. |
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