计算型腔模成型尺寸公式的修正系数

<正> 型腔模(压铸模、塑料模等)制件的成型,由于制件成型收缩时受各种影响,所以各种有关手册、资料中所列材料的收缩率只是一个范围。由于制件按平均收缩率计算,方法比较简便,故按照平均收缩率计算模具成型零件尺寸,是最常用的一种方法。     

消失模铸造铸件变形表面缺陷的防止

1铸件尺寸超差、变形 1.1 泡沫塑料的影响 (1)模具品质利用锻铝机加工模具,其尺寸精度、加工稳定性较好.发泡成型模具壁厚应均匀,型腔壁厚为8~10mm,分型面框架12~18mm,正常选择收缩率,准确确定型腔尺寸,要对型腔和镶嵌物进行精整和抛光以达到最佳精确尺寸.同时要正确选择取模方向,防止取模样是变形.     

大型塑料注射模具讲座(四)

<正> 成型零件是指构成模具型腔和型芯的零件,设计时必须准确地计算。由于塑料熔体的高压作用,为了满足使用时的要求,所以必须对成型零部件要做刚度和强度校核。 一、成型零件工作尺寸计算 大型塑料注射模具零件工作尺寸的确定,不能采用中小型模具零件计算方法,因为模具制造公差对中小型塑件尺寸精度影响很大,而塑料收缩率波动值却对大塑件(即大型模具)尺寸精度影响很大。在计算时根据四机部制订的塑件尺寸公差表和精度选用表为依据进行计算,同时考虑模具材料的热膨胀和塑件的综合收缩率进行讨论计算,而     

塑料收缩率和模具尺寸

设计塑料模时，确定了模具结构之后即可对模具的各部分进行详细设计，即确定各模板和零件的尺寸，型腔和型芯尺寸等。这时将涉及有关材料收缩率等主要的设计参数。因而只有具体地掌握成形塑料的收缩率才能确定型腔各部分的尺寸。即使所选模具结构正确，但所用参数不当，就不可能生产出品质合格的塑料。     

根据材料热膨胀性能准确计算玻璃型腔模成型尺寸

根据玻璃热膨胀性能及其影响因素，并考虑模具金属材料热膨胀性能，推导出玻璃型腔模具型腔和型芯的成型尺寸准确计算公式，对于尺寸精度要求高的玻璃制品其型腔模具的设计计算有一定指导意义。     

橡胶制品收缩率和型腔尺寸的确定

<正> 制品收缩率是模具型腔尺寸计算的依据,橡胶制品除要求必要的性能外,对制品的精度、形状和表面光洁度也有所要求。硫化出模的制品冷却到室温后,制品要小于型腔尺寸,即产生了收缩,其线性收缩率一般在1～2％,有的达3％以上。可见要获得尺寸精确的制品,研究模具型腔尺寸、制品尺寸和收缩率之间的关系是十分必要的,以     

一种型腔尺寸连续可变的薄壁塑件注射模设计

传统的注射成型模具通过更换镶块来实现型腔尺寸的变化,而更换镶块需要拆卸模具,使得操作繁琐、生产周期延长、模具制造成本增加,并且该种方式很难实现型腔尺寸的连续可变。为了解决以上难题,本文创新性提出运用T型滑块带动型腔滑板移动来实现型腔尺寸的连续可变,并设计完成型腔尺寸连续可变的薄壁塑件注射成型模具。运用所设计的模具进行注射成型实验,实验结果达到设计预期。     

根据材料热膨胀性能准确计算玻璃型腔膜成型尺寸

根据玻璃热膨胀性能及其影响因素，并考虑模具金属材料热膨胀性能，推导出玻璃型腔模具型腔和型芯的成型尺寸准确计算公式，对于尺寸精度要求高的玻璃制品其型腔膜具的设计计算有一定指导意义。     

对型腔模型芯,型腔径向尺寸计算公式之我见

在型腔模(压铸模、塑料模)中,按平均收缩率计算型芯径向尺寸,一般都用下式: 式中:d——制件为孔时的模具型芯尺寸,D′——制件为孔时的最小尺寸,K平——制件材料的平均收缩率,x—补偿系数,△——制件公差,δ——模具制造公差。按平均收缩率计算型腔径向尺寸时,一般都用下式:     

注射成型塑料齿轮收缩率计算

讨论了注射成型塑料齿轮的收缩机理,介绍了影响成型收缩率的主要因素。通过对塑件成型制品的收缩规则和收缩特性分析,提出了塑料齿轮向"对称中心"收缩的概念,利用实例计算,得出模具型腔与塑料齿轮的关系式,并对收缩角和实际收缩率进行了阐述。由渐开线模具型腔得到的塑料齿轮,其齿形也是渐开线。     

Part shrinkage anomilies from stereolithography injection mould tooling

The use of stereolithography (SL) tooling allows plastic parts to be produced by injection moulding in a very short time due to the speed of mould production. One of the supposed advantages of the process is that it provides a low volume of parts that are the same as parts that would be produced by the conventional hard tooling in a fraction of the time and cost.However, this work demonstrates different rates of polymer shrinkage are developed by parts produced by SL and conventional tooling methods. These revelations may counter the greatest advantages of the SL injection moulding tooling process as the parts do not replicate those that would be produced by conventional hard tooling.This work identifies the different shrinkage that occurs in mouldings produced by an SL mould as compared to those produced from an aluminium mould. The experiments utilise two very different types of polymers and two mould geometries, which are processed in the same manner so that the heat transfer characteristics of the moulds are isolated as the only experimental variable.The work demonstrates how the two mould materials exhibit very different rates of expansion due to the temperature profiles experienced during moulding. This expansion must be compensated for to establish the total amount of shrinkage incurred by moulded parts. The compensation is derived by a mathematical approach and by modelling using finite element analysis. Both techniques depend upon knowledge of the thermal conditions during moulding. Knowledge of these thermal conditions are obtained by real-time data acquisition and simulated by FEA modeling. The application of the findings provide knowledge of the complete shrinkage values relating to the mould material and polymer used which would enable the production of geometrically accurate parts.     

微结构塑件模具温度控制探讨

由于微型件结构上的特点,微结构注射充满型腔的能力要比常规注射差得多。通过对塑料熔体在型腔中的流动性分析和模具温度控制方式的比较,确定了微结构塑件在注射过程中模具温度控制的优化方案。这种方法对于指导实际生产具有较高的实用价值,并取得了良好的效果。     

射钉保护导向套注射模设计

分析了射钉保护导向套的结构特点，介绍了注射模的结构、型腔的加工工艺和工作过程。着重阐述了小塑料件注射模的浇注系统和排气系统，对同类注射模设计有一定的参考价值。     

水泵接口与法兰同模成型注射模设计

介绍了水泵接口与法兰的结构与成型工艺,通过在模具型腔设置隔离板,改变分流道的布局,实现2个塑件的同模注射成型,保证了2个塑件生产中的成组配套,成型的塑件质量良好,具有较好的经济效益。     

带转动脱模机构的注射模设计

分析了粗纱管塑件的工艺特点,阐述了深腔塑件注射模的结构设计方法,提出了采用转动脱模机构的脱模方式,解决了深腔塑件脱模行程大的问题。该模具结构紧凑,制造简便,操作方便,生产效率高。     

全自动级进式端子注射模设计技巧

根据五金端子制品的结构特点,对全自动级进式端子注射模设计进行了探索和研究。重点阐述了分型面选择、端子在模具中的定位、模具型腔数量及其布置、制品收缩率、封胶形式、模具与端子相关配合尺寸、浇注系统设计和推杆布置等方面的经验及技巧。对提高全自动级进式端子注射模的设计水平有一定的帮助。     

The structure of parts produced by stereolithography injection mould tools and the effect on part shrinkage

Stereolithography (SL) tooling for plastic injection moulding provides a low cost and quick alternative to hard tooling methods when producing a small quantity of parts. However, work by the authors has shown that a different rate of polymer shrinkage was experienced in semi-crystalline parts when produced from SL moulds as compared to those from conventional metal tooling methods. Different shrinkage means the parts are not truly the same as those that would be produced by metal tooling and highlights a disadvantage to SL tooling.This work associates the increased shrinkage experienced to a greater percentage crystallinity developed in the parts due to their thermal history during processing. In these experiments the cooling rate, which is imparted due to the heat transfer characteristics of the mould has been identified as the controlling factor of a parts % crystalline content and the cause of shrinkage anomalies.The morphology analysis results show that there is 30% more crystallinity developed in the nylon (PA66) parts produced in SL moulds than those produced from aluminium moulds. The results also reveal different characteristics during thermal analysis that may also be due to the thermal history imparted by the mould.The work utilises the thermal analysis technique differential scanning calorimetry (DSC) to quantify the different levels of crystallinity in the parts. The thermal characteristics of the mould are demonstrated by real-time data acquisition.     

湿型球墨铸铁件收缩特性的试验研究

采用正交试验的方法，浇注一系列铸件，测量铸件的冷却曲线；解剖铸件，测定铸件质量、铸件及缩孔体积。研究了碳当量、孕育、铸件模数以及铸型条件对湿型球铁件收缩特性及缩孔缩松的影响。为开展数值模拟预测球铁件缩孔、缩松的工作打下了基础。     

基于超薄壁汽车门饰板成型缺陷的注射关键技术研究

针对壁厚为1.8 mm的超薄壁汽车门饰板注射成型,结合实际试模、有限元模拟与实际经验,对试模过程中出现的飞边、缩印、光泽度差异、推杆印与塑件尺寸超差等缺陷进行了研究,通过优化模具与塑件的结构,改善了薄壁汽车门饰板的注射成型缺陷,满足了塑件的实际生产要求。