Rapid tooling technology is a new technology developed with the emergence of rapid prototyping technology. Low pressure injection molding of rapid tooling refers to the process in which the bicomponent materials with high chemical activity and low relative molecular weight are mixed in a certain proportion and injected into the closed mold under low pressure (0.4 ~ 0.5MPa), which completes the chemical reactions such as polymerization, crosslinking and curing, and finally forms products after cooling and solidification. It is the process of low pressure perfusion molding (RIM) technology in rapid tooling products molding Field development. The product material is generally polyurethane resin, which has the properties of thermosetting material after molding - the product quality is closely related to the mold structure, filling process, mold temperature, initial temperature of raw materials, material mixing ratio, mixing uniformity, curing time, etc.
               

　　低压灌注成型的工艺流程及成型原理

　　Technological process and forming principle of low pressure pouring molding

　　快速模具低压灌注成型是指将聚氨酯树脂注射进快速模具并固化成型的过程。可使用硅胶模具、聚氨酯模具、环氧树脂模具、ABS模具及铝合金模具。低压灌注成型设备主要由控制箱、定量泵、混合头及喷嘴等组成。工艺流程见图1。低压灌注成型设备在0.4~0.5MPA的低压下将双组分的聚氨酯材料用定量泵送入混合头，经撞击混合后再注入模具。混合后的双组分材料在模具内快速反应，进行聚合交联固化。为保证材料充分固化，减少制品变形，一般在注射完成后，需要将模具移到烘箱内进行后固化，约1.5~2.0小时后脱模得到制品。通常一副模具的制作周期为3~4天，可生产100~500件左右产品。按照工艺要求，模具和材料在注射前均应加热。由于双组分材料的固化反应，在成型过程的初始阶段，整个反应体系的温度还将进一步上升，出现放热现象。

　　Low pressure injection molding of rapid tooling refers to the process of injecting polyurethane resin into rapid tooling and curing molding. Silicone mold, polyurethane mold, epoxy resin mold, ABS mold and aluminum alloy mold can be used. Low pressure injection molding equipment is mainly composed of control box, quantitative pump, mixing head and nozzle. The process flow is shown in Figure 1. Under the low pressure of 0.4 ~ 0.5MPa, the two-component polyurethane material is pumped into the mixing head by a quantitative pump, and then injected into the mold after impact mixing. After mixing, the two-component materials react rapidly in the mold and are polymerized and crosslinked. In order to ensure that the material is fully solidified and reduce the deformation of the product, the mold should be moved to the oven for post curing after the injection, and the product can be demoulded after about 1.5 ~ 2.0 hours. Generally, the production cycle of a pair of dies is 3-4 days, which can produce about 100-500 pieces of products. According to the process requirements, the mold and material should be heated before injection. Due to the curing reaction of the two-component material, the temperature of the whole reaction system will rise further and exothermic phenomenon will appear in the initial stage of the molding process.

　　低压灌注成型使用的材料主要以聚氨酯材料为主。改变材料的混合比例，可获得不同的材料弹性模量，从而得到所需要的材料特性!固化后的材料物理性能类似于普通热塑性材料ABS、PP或PS。适合于较大壁厚（>4mm）及不均匀壁厚制品的生产.

　　Polyurethane is the main material used in low pressure injection molding. The physical properties of cured materials are similar to those of ordinary thermoplastic materials ABS, PP or PS. It is suitable for the production of larger wall thickness (> 4mm) and non-uniform wall thickness products

　　以上是关于快速模具低压灌注成型的相关介绍，想要了解更多内容欢迎点击山东快速成型模具http://www.axcwv.cn官网。

　　The above is about the rapid mold low pressure perfusion molding related introduction, want to know more content, welcome to click Shandong rapid prototyping mold http://www.axcwv.cn Official website.