Shanghai Daoqin Plastics Co., Ltd.

         front 言

         rotational molding process is plastics molding processing in important separation 支, upper 世纪40 year 代问世以, semi more development, its equipment and process day 趋完善, in 欧州发达国家 to application, from small 巧 儿童 toys to automotive plastics parts, 直至庞 large engineering plastics products. especially is large type and type in products, due to process its features made, in can rotational molding molding process can formed.

        一, rotational molding molding process

         process principle

        先 will plastics add mold in, rear mold 沿两垂直轴不断旋转并 make add hot, inner plastics in heavy force and hot can function lower, uniform coating 布, melt viscous mold cavity surface upper, molding is need 形状, again cooling type made.

         molding process

        二, rotational molding molding control key points (effect/influence factors)

        1, raw materials resin property can effect/influence

         resin powder material flow property, distribution, table/sheet density, pellets for molding products has effect/influence. 据实验 analysis 知: distribution value 位置越 high, pellets fine, products comprehensive property can excellent. from comprehensive production cost and efficiency 考虑, production generally will distribution value in 60—80 between is most good.

        2, add hot temperature degree and time for rotational molding molding effect/influence

         add hot temperature degree and add hot time need to multiple factors effect/influence, its in most main/primary has molding use resin, mold and products and other factors.

        例如: polyethylene (PE) rotational molding molding add hot temperature degree usually in 250℃～400℃, specific product rotational molding add hot conditions can 经由实验确定, experiment/testing conditions can 取 220℃, 10min.

        若 products defect or products in 尚残存 has micro small bubbles (melt gas 体未充 separation 排出), 则应适当延 long add hot time or 者适当 improve/increase add hot temperature degree;若 products color 发黄, table/sheet material material add hot degree generate hot oxidation aging phenomenon, need shrink short add hot time or 者适当 reduce add hot temperature degree.

        3, speed degree and rise temperature speed degree for rotational molding molding effect/influence

         usually lower, mold speed degree control is 6—35rpm.

         this need products and structure, if is 圆柱形 products, speed degree can high; if is has 棱角, 转角, and other non property products, speed degree need versus low. if can positive 确估计 需 转 speed, can through powder material mold inner adjustment speed.

        4, cooling for rotational molding molding effect/influence

         cooling rotational molding process in non important ring, full material material in mold cavity inner rear, can 开始保 temperature type.

         currently, rotational molding industry cooling methods generally has water cold and cold types. water cold efficiency relatively high, product easy generate shrinkage deformation. cold efficiency relatively low, quality stability property relatively good.

        5, demolding agent effect/influence

         has machine silicon resin type demolding agent application 当, can make products easy from inner 取出, from improve/increase production efficiency, decrease/reduce products in demolding can can formed loss, but also coating one-time demolding agent can use more 次.

        实践 can 知, in coating has machine silicon resin front, must will mold cavity surface dry 净. has machine silicon resin need coating uniform, coating 不宜太 thick, coating good rear need add hot make solvent agent 挥发完毕以 rear, high temperature (220℃一250℃) lower add hot 2 small above, make crosslinked, from to tool has good machine strong/high degree demolding agent 层.

        三, rotational molding main features

         advantages

        1, rotational molding mold cost low ——同 and other specifications large small product, rotational molding mold cost is blow molding, injection molding mold cost 1/3 to 1/4, combined large type plastics products;

        2, rotational molding product strong/high degree good —— rotational molding can achieve product thick degree ultra- 5mm, solution in product relatively thin issues;

        3, rotational molding can various parts;

        4, rotational molding product can non complex, thick degree can ultra- 5mm above;

        5, rotational molding can production full product;

        6, rotational molding product can filling foaming material, achieve temperature;

        7, must adjustment mold, rotational molding product thick can adjustment (2mm above);

        8, 适于模塑 large type and large type made parts;

        9, rotational molding molding easy products color —— rotational molding molding will material material add to mold in, make material material full 部进入, products from mold in 取出以 rear again add lower molding need material material. 当我们 in use more mold rotational molding molding types plastics products 时, also can in different mold in add different color material material, meanwhile rotational molding different color plastics products;

        10, Raw Materials —— rotational molding products thick comparison uniform 且倒角处稍 thick, can separation material material can, has 利于节约 Raw Materials; in addition, in rotational molding molding process in, has runner, gate and other waste material, debugging good rear, production process in 几乎没回炉 material, therefore process for/regarding material material utilizing rate high.

         disadvantages

        1, processing cycle long, combined large amount production;

        2, can amount utilizing rate low lower, liquid add hot, a large amount of hot amount 流失造 formed can 源浪费;

        3, 模塑材 material selection has 限, currently used for rotational molding molding material has a small amount of types, 我国99% rotational molding products material is PE, its in 95% is suitable for rotational molding molding rotational molding grade LLDPE. although nylon, polycarbonate (PC), ABS and other multiple plastics has using/adopting rotational molding process molding, application non narrow;

        4, material cost relatively high, need selection additives and made formed fine powder 末;

        5, 一 形状 products (如肋筋状 products) comparison difficult;

        6, versus for injection molding, blow molding, 每次卸 products and raw materials mold opening 麻烦, 工人劳动 strong/high degree relatively large.

        四, rotational molding products application scope

        1, container type rotational molding made parts

        广泛 used for water 槽, various liquid chemical product 贮槽(如 acid, alkali, salt, chemical material, and other), use container (汽油贮槽 and automotive, machine use 油箱), battery housing/shell and other.

        2, automotive use rotational molding made parts

         main/primary is application polyethylene (PE) and polyvinyl chloride (PVC) resin, rotational molding formed various pipe fittings, 如空调弯 tube/pipe, 靠背, and other.

        3, device and various use product

         main/primary has polyvinyl chloride (PVC) rotational molding various made parts, water 球, 浮球, 自行车 base/seat 垫, small and and between 缓冲吸震 device and other.

        4, toys, 模特儿, process product and other

         due to rotational molding mold can using/adopting precision 浇注, electrical and other process manufacturing; rotational molding made parts surface for mold type surface fine structure “复 made ”效果 very good, therefore rotational molding method can make products as versus 当精致美观, used for made tool has relatively large 观赏价 value product, especially is toys, 模特儿, process product and other.

        5, various 箱体, housing/shell 体, large type pipe/tube and other made parts

        如 turnover box, waste 箱, machine outer housing/shell, anti 护罩, lamp covers, 浴室, therefore and electrical 话间, and other. rotational molding product in liquid chemical product 贮运, chemical industry enterprise, industrial coating 装, dilute made in 洗槽, reaction and other, in 河海浮标, active water tank and other field/area use already has effect/influence.