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模具对注塑系统中浇口都有那些要求呢?

来源:http://www.ok9868.com     发布时间:2019-12-24 15:12:34    点击:

  浇口是浇注系统中物料流动通道的重要组成部分。除主浇道外,浇道大部分为浇注系统中截面更小的部位,其值一般仅为引水渠道截面的3% ~ 9%。针对小门成形过程中由于流动阻力增大而引起的压降,可采用增大注射压力的方法在一定范围内进行补偿。一般来说,采用小门注射成型,具有以下优点。
  Gate is an important part of material flow channel in gating system. Except for the main sprue, most of the sprue is the part with the smallest section in the pouring system, and its value is generally only 3% - 9% of the section of the diversion channel. In view of the pressure drop caused by the increase of flow resistance, the method of increasing injection pressure can be used to compensate in a certain range. Generally speaking, small door injection molding has the following advantages.
  1. 之间有一个大的压力差的前后两端小的门,可有效提高熔体的剪切速率,生成一个大的剪切热,造成熔体的表观粘度下降,流动性增加,这有利于模具填充。这种小浇口的特性对薄壁制品或细纹制品,以及对塑料成型制品,如聚乙烯(PE)、聚丙烯(PP)、聚苯乙烯(PS)等粘度对剪切速率敏感的制品有很大的好处。
  1. There is a big pressure difference between the front and the back of the small door at both ends, which can effectively improve the shear rate of the melt, generate a large shear heat, resulting in the decrease of the apparent viscosity of the melt, and increase the fluidity, which is conducive to mold filling. The characteristics of the small gate have great advantages for thin-walled products or fine grain products, as well as for plastic molding products, such as polyethylene (PE), polypropylene (PP), polystyrene (PS) and other products with viscosity sensitive to shear rate.
  2,因为大门的小体积,冻结速度快,所以生产的一些产品,可以冻结后的小门,里面的产品不需要治疗,只要外部固化层可以demold产品有足够的强度和刚度,从而缩短成型周期,提高生产效率。
  2. Because of the small size and fast freezing speed of the gate, some products can be frozen. The products inside do not need treatment. As long as the external curing layer can demold products have enough strength and rigidity, so as to shorten the molding cycle and improve the production efficiency.
  3.在注塑成型过程中,保持压力和填充的阶段一般要持续到浇口处的熔体冻结,否则型腔内的熔体会回流到型腔外。如果浇口尺寸较大,压缩和充型时间较长,可能会增加大分子的取向和流动变形,导致产品的充型应力较大,特别是浇口附近,导致产品翘曲变形。如果使用一个小浇口,可以调整的体积小浇口通过模具测试或模具修理,所以融化在浇口冻结在时间过程中保持压力,以便正确地控制充填时间和避免上述现象。
济南模具
  3. In the process of injection molding, the stage of maintaining pressure and filling generally lasts until the melt at the gate freezes, otherwise the melt in the cavity will return to the outside of the cavity. If the gate size is large and the compression and filling time is long, the orientation and flow deformation of macromolecules may be increased, resulting in a large filling stress of the product, especially near the gate, resulting in warpage and deformation of the product. If a small gate is used, the adjustable volume of the small gate passes the mold test or the mold repair, so the melting keeps the pressure during the time when the gate freezes, so as to correctly control the filling time and avoid the above phenomena.
  4,如果使用一个更大的门成型的产品,在产品表面质量要求较高,通常需要合适的工具或机床产品处理后去除疤痕,特别是当门太大,必须锯门凝固,减少和其他方法来删除。然而,这可以通过使用小的门来避免。例如,在拆卸时,小浇口凝结剂可以用手工或特殊的模具结构自动清除。此外,小门后的疤痕较小,一般不需要或只需要稍作修整即可。因此,小喷溅的使用不仅有利于产品的浇注系统,也有利于产品的精加工。
  4. If using a larger door shaped product, the product surface quality requirements are higher, usually need appropriate tools or machine tool products to remove scars after treatment, especially when the door is too large, must saw the door solidification, reduce and other methods to delete. However, this can be avoided by using small doors. For example, during disassembly, the small gate coagulant can be removed automatically by hand or special mold structure. In addition, the scar behind the small door is smaller, and generally it is not necessary or only needs to be slightly trimmed. Therefore, the use of small splash is not only conducive to the pouring system of the product, but also conducive to the finishing of the product.
  5. 如果在多腔非平衡浇注系统中使用小浇口,浇口对塑料熔体的流动阻力将比多通道熔体大得多。因此,熔体有可能填满通道并在每个模腔几乎同时填满之前建立足够的压力。因此,小浇口可以平衡多模腔内各模腔的进给速度,有利于浇注系统的平衡。
  5. If the small gate is used in the multi cavity unbalanced pouring system, the flow resistance of the gate to the plastic melt will be much greater than that of the multi-channel melt. Therefore, it is possible for the melt to fill the channel and establish sufficient pressure before each cavity is almost filled at the same time. Therefore, the small gate can balance the feed speed of each cavity in the multi-mode cavity, which is conducive to the balance of the gating system.
  同时要注意的是,虽然小浇口具有上述优点,但过小的浇口会造成较大的流动阻力,导致加料充型时间延长。因此,对于某些高粘度或剪切速率的塑料熔体,其表观粘度影响不大(如聚甲酸酯、聚砜等),不宜采用小门造型。此外,在形成大型产品时,还应注意扩大浇口面积,有时甚至需要扩大浇口截面的高度,以接近产品的厚度,以提高熔体的流动性。除了以上情况外,由于壁厚较大,产品的收缩率也较大,一般需要有足够的时间来弥补,所以在这种情况下,浇口面积不能设计得太小。
  At the same time, it should be noted that although the small gate has the above advantages, too small gate will cause greater flow resistance, resulting in longer filling time. Therefore, for some high viscosity or shear rate plastic melts, the apparent viscosity has little effect (such as polycarboxylate, polysulfone, etc.), so it is not suitable to use small door modeling. In addition, when forming large-scale products, we should also pay attention to expanding the gate area, sometimes even need to expand the height of the gate section, in order to approach the maximum thickness of the product, in order to improve the fluidity of the melt. In addition to the above, due to the large wall thickness, the product shrinkage is also large, generally need to have enough time to make up, so in this case, the gate area can not be designed too small.
  以上就是济南模具对注塑系统中小浇口的详细介绍,想要了解更多请点击官网http://www.ok9868.com
The above is the detailed introduction of Jinan mold to the small and medium gate of injection system. For more information, please click http://www.ok9868.com
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