Shanghai Daoqin Plastics Co., Ltd.

         and runner mold versus ratio, hot runner mold in system in use process in 始终处于 high temperature 状态, plastics melt in high temperature, high pressure function lower very easy in hot runner system parts 连接处发生泄漏. melt not only effect/influence parts quality, but also heavy loss bad mold,导致无 method production. hot runner mold 发生泄露 部位 main/primary has 两,一 is runner sheet/plate upper runner 端面处,二 is runner sheet/plate and nozzle (包括 gate nozzle and runner nozzle) combined 面处. melt causes multiple more 样,归 nano can separation is as, assembly process 不当,密封 design combined 理3 方面. 本文就 melt causes and anti measures as introduction.

        1 process factors melt 泄漏

        操 as process is mold production process in melt main/primary causes 之一. is hot runner system parts hot 膨胀, in design and assembly mold 时, parts 间往往存 in cold 间隙. has in 规定 操 as temperature degree lower, parts hot 膨胀才 can full remove cold 间隙达 to anti 漏. as 不当引起 melt main/primary in below/following types lower:(1) system rise temperature process or temperature degree control non-uniform melt 泄漏. in rise temperature process in,如 nozzle rise temperature speed degree high hot runner sheet/plate rise temperature speed degree, system parts toward hot rear will made hot runner sheet/plate toward hot 膨胀,引起 hot runner sheet/plate deformation 而出现 melt 泄漏. system parts temperature degree non-uniform 会引起 parts non-uniform 膨胀,也会 make parts 发生扭曲 deformation 而出现 melt 泄漏. (2) system has to 规定 操 as temperature degree front injection. 如 示, system hot rear 支承圈6, hot runner sheet/plate 5 and gate nozzle 4 in direction hot 膨胀,支承圈 pressure in 定模安装 sheet/plate 3 upper,并 in hot runner sheet/plate and nozzle generate hot pressure. in has to temperature degree 时进行 injection, hot generate hot pressure 不足以抵消 melt pressure will make nozzle 4 and hot runner sheet/plate 5发生 separation 离而出现 melt 泄漏. (3) system add hot temperature degree high as temperature degree melt 泄漏. in this type of lower, due to hot amount large generate very large hot pressure,会 make system parts deformation 而出现 melt 泄漏.

        另一方面,当浇注 system temperature degree reduce is as temperature degree 时, due to belt/tape rigid property hot nozzle for hot 膨胀 适应 property 差,也会出现 melt 泄漏.

        综 upper 述,按 positive steps and process conditions 进行操 as is melt front 提. generally hot runner mold can lower steps 进行操 as:

        (1) add hot hot runner system to setting temperature degree. generally separation is 两步进行:首先 is? soft 启动,以消 remove add hot device in gas.

        (2) add hot mold to setting temperature degree. especially is large type mold, injection front add hot, injection again cooling.

        (3) add hot injection machine material to setting temperature degree.

        第二步,满 negative will system add hot to setting temperature degree, can will nozzle temperature degree add hot to hot runner sheet/plate temperature degree 2/3,待 hot runner sheet/plate temperature degree to design temperature degree rear again will nozzle temperature degree add hot to setting temperature degree.

        (4) for new or already hot runner system,应先 using/adopting low pressure slow speed injection.

        (5) injection several ring rear has melt phenomenon, again using/adopting injection process parameters production.

        2 hot runner system design

        2.1 hot runner system hot 膨胀补偿

         room temperature lower assembly mold in hot runner system parts hot 膨胀时会引起 parts generate versus for 位置 变化, is parts hot 膨胀,需留出 combined 适 膨胀间隙,如 示 cold 间隙A and C. hot runner sheet/plate through in 心定位销7 solid in sheet/plate 1 upper,受 hot rear toward 四周伸 long. hot runner sheet/plate toward hot will decrease small hot runner sheet/plate and 止转销2 间隙A,如 design 时A value small hot runner sheet/plate toward hot amount,受 hot rear 止转销 will retardant hot runner sheet/plate toward long,造 formed hot runner sheet/plate warpage deformation, make hot runner sheet/plate and nozzle 间密封失效而引起 melt 泄漏. 支承圈6, hot runner sheet/plate 5, gate nozzle 4 轴 toward hot will remove cold 间隙C.如 cold large,轴 toward hot amount 不足, in injection melt pressure will make gate nozzle 4 and hot runner sheet/plate 5发生 separation 离出现 melt 泄漏. cold small, system hot pressure large, will make system parts bending, or pressure force ultra- 定模 sheet/plate 屈服应 force, make 支承圈 pressure 溃定模 sheet/plate, from made hot runner sheet/plate toward hot 膨胀,造 formed gate nozzle and hot runner sheet/plate 间发生 melt 泄漏. therefore, in design mold 时, positive 确计算 system hot amount,留出 combined hot 膨胀间隙 is anti melt front 提. system property hot amount can using/adopting lower 列公式计算:L=TL(1) system hot 膨胀受 retardant generate hot force is:=EL-CL(2)定模 solid sheet/plate pressure using/adopting lower 式校核p(3)式 in:L is hot runner system property hot amount,mm; is system parts material thermal expansion coefficient;T is hot runner system parts and mold temperature 差;L is room temperature lower runner system parts in direction upper long degree,mm; is system hot 膨胀受 retardant generate hot force,MPa;C is 预留间隙 amount,mm;E is system parts elastic property modulus,MPa;p is solid sheet/plate material use pressure force.

        2.2 hot runner system 密封形式

         hot runner sheet/plate and nozzle using/adopting 平面密封, is outer hot runner system Common types 密封形式. system toward hot rear 支承圈 pressure in solid sheet/plate upper, in hot runner sheet/plate and nozzle combined 平面处 generate hot pressure melt pressure 进行密封 anti 漏. this type of structure 形式不 can ensure cold 密封,也没 has hot measures, has in setting temperature degree conditions lower can ensure hot runner sheet/plate and nozzle 密封. design 时需准确计算 hot amount,留出 combined cold 间隙C.

        b in nozzle and hot runner sheet/plate combined upper using/adopting O type 密封圈,O type 密封圈 use 不锈钢 tube/pipe made formed, assembly has 2030钢 tube/pipe 直径 预紧 amount anti melt 泄漏. this type of structure non combined low rigid degree hot runner sheet/plate and mold.

         using/adopting elastic property 连接,由 elastic provide force achieve cooling lower 密封, hot elastic absorption hot anti system loss bad and 泄漏, is types relatively is 理想 密封形式.

         gate nozzle through solid in hot runner sheet/plate upper, system hot 膨胀时 nozzle and sliding pressure ring hot runner sheet/plate 一起移动. due to nozzle 移动会造 formed nozzle runner and sheet/plate upper gate 轴线 错位, therefore in design nozzle 位置时需考虑横 toward hot amount. this type of 密封形式 suitable for injection less, nozzle 间距不 large combined.

        3 hot runner sheet/plate assembly process

         hot runner system assembly degree and 安装次序直接关系 to melt is 否发生泄漏. nozzle high degree 不一致, most short nozzle and hot runner sheet/plate in 间隙会引起 melt 泄漏,支承垫 high degree and nozzle high degree 不一致引起 hot runner sheet/plate deformation 也会造 formed melt and other.

         lower 面以1模4腔 plastics box/case hot runner mold is 例说明 hot runner sheet/plate assembly process:(1)紧 solid solid sheet/plate. (2) will runner 堵塞7 pressure hot runner sheet/plate 10,找 positive direction rear 装入止转销2 anti 转,然 rear use pressure 紧螺钉3 pressure 紧堵塞,并 use O type metal 密封圈 anti melt 泄漏. (3) will gate nozzle 1 and 支承垫15安装 in sheet/plate 14 in,以定模 sheet/plate is 基准检验 has nozzle assembly high degree is 否一致,如不一致,按 most small value 进行修 abrasion,允差 is 0.01mm. (4)试装 hot runner sheet/plate,检验 hot runner sheet/plate and 止转销2径 toward and toward is has necessary 间隙A and B.(5) use will sheet/plate frame 12 solid in sheet/plate 14 upper. (6)以垫 sheet/plate frame 12 upper is 基准,修配 has pressure 圈6, make its high degree 一致,并 and sheet/plate frame upper has 间隙C.(7) will runner nozzle 9旋入 hot runner sheet/plate 10.