第10讲 脱模机构设计 PPT
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摘要塑料是一种可塑性的合成高分子材料,具有重量轻且坚固,耐化学腐蚀,电绝缘性好,价格便宜,可塑性好等特点,广泛应用于电脑、手机、汽车、电机、电器、家电和通讯产品制造中。
注塑成形是成形塑件的主要方法之一,是指使用注塑机将热塑性塑料熔体在高压下注入到模具内经冷却固化获得产品的方法。
注塑的优点是生产速度快,效率高,操作可自动化,能成型形状复杂的零件,特别适合大量生产。
本次课程设计的产品为电源按键,具有重量轻,强度高,耐腐蚀,易清洁等特点,为大批量生产产品。
本次设计在针对产品进行工艺性分析后,确定模具分型面、型腔数目、浇口形式、位置大小;其中最重要的是确定型芯和型腔的结构,以及它们的定位和紧固方式。
此外还进行了脱模机构的设计,合模导向机构的设计,冷却系统的设计等。
最后绘制完整的模具装配总图和主要的模具零件图及编制成型零部件的制造加工工艺过程卡片。
实践证明:该模具结构合理、可靠,并能保证产品质量,对此类注塑产品的模具设计有参考价值。
关键词:塑料 , 注塑成形 , 模具设计AbstractPlastic is a synthetic polymer material , with the characteristics of plasticity, light weight, sturdiness, electrical insulation, and which is resistance to chemical corrosion and cheap. It is widely used in computers, mobile phones, cars, motors, electrical, home appliances and communication products manufacturing. Injection molding is one of the main methods of forming plastic parts, it refers to the use of plastic injection machine to inject the thermoplastic melts into the mold under high pressure , after cooled to obtain the products . It has the advantage of fast production speed , high production efficiency , and automated operations , it can form the shape of complex parts, particularly suitable for mass production. The production of graduation project is power button , which has a light weight , high strength , corrosion resistance and easy cleaning features for mass production . After analysis the process of the product , the mold parting line , cavity number , gate form , gate location can be determined , one of the most important is to identify core and cavity structures , as well as their positioning and fastening methods. In addition, it also carries out the design of stripping agencies , mold-oriented organizations and the cooling system .At last, draw a complete mold assembly drawing , major parts diagram , and draw up cards of parts manufacturing and processing process . It is proved that the mold structure is reasonable , reliable and can guarantee product quality , and is valuable for the injection mold design of such products .Key Words:Plastic , Injection molding , Mold design1.1 引言随着塑料工业的飞速发展和通用塑料与工程塑料在强度和精度等方面的不断提高,塑料制品的应用范围也在不断地扩大,如:家用电器、仪器仪表、建筑器材、汽车工业、日用五金等众多领域,塑料制品所占的比例正迅速增加,由于在工业产品中,一个设计合理的塑料件往往能代替多个传统金属结构件,加上利用工程塑料特有的性质,可以一次成型非常复杂的形状,并且还能设计成卡装结构,成倍地减少整个产品中的各种紧固件,大大地降低了金属材料消耗量和加工及装配件工时,因此,近年来工业产品塑料化的趋势不断上升。
4.14.7 脱模推出机构的设计1.推出方式的确定本塑件圆周采用脱模板,中心采用推杆的综合推出方式。
脱模板推出时为了减小脱模板与型芯的摩擦,设计中在用脱模板与型芯之间留出0.2mm 的间隙,并采用锥面配合,如图4-340所示,可以防止脱模板因偏心而产生溢料,同时避免了脱模板与型芯产生摩擦。
2.脱模力的计算⑴ 圆柱大型芯脱模力 因为1013339>===t r λ,所以,此处视为薄壁圆筒塑件,根据式4-24脱模力为 NNN A K f tESL F 4.34503914.31.0)1cos 1sin 45.01)(3.01()1tan -45.01cos )329(0055.08.1314.321.0)1()tan (cos 22321≈⨯⨯++-⨯⨯-⨯⨯⨯⨯⨯=+--=(μϕϕπ 式中各项的意义,见4.9.2节内容。
⑵ 成型塑件内部圆筒型芯的脱模力计算 因为105.237<===t r λ,所以此处视为厚壁圆筒塑件,同时,由于该塑件的内孔是通孔,所以,脱模力不存在真空压力,参考式(4-24)可得脱模力为NN K K f rESL F 9.4096)1cos 1sin 45.01)(1cos )21(2)1(cos )21(23.01()1tan 45.0(340055.0108.1714.32)1()tan (22223212=+⨯⨯+⨯++-⨯⨯⨯⨯⨯⨯⨯=++-=︒︒︒︒︒μϕπ 对于塑件的四个肋板,由于是径向布置,冷却收缩是径向收缩,所以对型芯的箍紧力不是太大,主要是粘模力,可以按计算脱模力乘以一个不太大的系数,此处考虑为1.2。
3.校核推出机构作用在塑件的单位压应力⑴ 推出面积22222210.1254)4.7888(4)(4mm mm d D A =-=-=ππ2222212121.160)1420(4)(4mm mm d D A =-=-=ππ⑵ 推出应力抗压强度)合格(5305.51.1600.1254)9.40964.3050(2.1)(2.12.12121Mpa Mpa A A F F A F <=++⨯=++==σ4.14.8 冷却系统的设计冷却系统的设计很麻烦,在此只进行简单的计算。