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注塑成型常见问题龟裂

来源:http://www.sdlqmj.com 日期:2019-01-10 发布人:admin 浏览次数:
注塑成型常见问题龟裂
Common Problems of Injection Molding Crack
龟裂是塑料制品较罕见的一种缺陷,发生的次要缘由是由于应力变形所致。次要有剩余应力、内部应力和内部环境所发生的应力变形。
Crack is a rare defect in plastic products, which is mainly caused by stress and deformation. Secondly, there are residual stress, internal stress and stress deformation in the internal environment.
剩余应力惹起的龟裂
Cracks caused by residual stress
剩余应力次要由于以下三种状况,即充填过剩、脱模推出和金属镶嵌件形成的。作爲 在充填过剩的状况下发生的龟裂,其处理办法次要可在以下几方面动手:
The residual stress is mainly due to the following three conditions: excessive filling, demoulding and metal inlay. As a crack occurring in the condition of overfilling, its treatment can be carried out in the following aspects:
(1)由于直浇口压力损失小,所以,假如龟裂次要发生在直浇口左近,则可思索改用多点散布点浇口、侧浇口及柄形浇口方式。
(1) Because the pressure loss of the direct gate is the smallest, if the crack occurs mostly near the left of the direct gate, the multi-point sprinkler gate, side gate and handle gate can be considered.
(2)在保证树脂不分解、不劣化的前提下,适当进步树脂温度可以降低熔融粘度,进步活动性,同时也可以降低注射压力,以减小应力。
(2) On the premise of guaranteeing the non-decomposition and non-deterioration of the resin, properly improving the temperature of the resin can reduce the melting viscosity, improve the activity, and at the same time reduce the injection pressure, so as to reduce the stress.
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(3)普通状况下,模温较低时容易发生应力,应适当进步温度。但当注射速度较高时,即便模温低一些,也可减低应力的发生。
(3) Under normal conditions, the stress is easy to occur when the die temperature is low, and the temperature should be properly improved. However, when the injection rate is higher, the stress can be reduced even if the die temperature is lower.
(4)注射和保压工夫过长也会发生应力,将其适当延长或停止Th次保压切换效果较好。
(4) The stress will also occur if the injection and holding time are too long. It is better to prolong or stop Th times holding switching properly.
(5)非结晶性树脂,如 AS树脂、 ABS树脂、 PMMA树脂等较结晶性树脂如聚乙烯、聚甲醛等容易发生剩余应力,应予以留意。
(5) Non-crystalline resins, such as AS resin, ABS resin, PMMA resin, are more prone to residual stress than crystalline resins such as polyethylene and polyformaldehyde, and should be noted.
脱模推出时,由于脱模斜度小、模具型胶及凸模粗糙,使推出力过大,发生应力,有时甚至在推出杆四周发生白化或决裂景象。只需细心察看龟裂发生的地位,即可确定缘由。
When demoulding is launched, because of the small slope of demoulding, the roughness of mould glue and punch, the pushing force is too large and the stress occurs, sometimes whitening or cracking occurs around the pushing rod. The cause can be ascertained only by carefully examining the position of the cracks.
在注射成型的同时嵌入金属件时,容易发生应力,而且容易在经过一段工夫后才发生龟裂,危害极大。这次要是由于金属和树脂的热收缩系数相差悬殊发生应力,而且随着工夫的推移,应力超越逐步劣化的树脂资料的强度而发生裂纹。爲预防由此发生的龟裂,作爲经历,壁厚7"与嵌入金属件的外径  三、皱招及麻面
When metal parts are embedded in injection moulding, stress is most likely to occur, and cracks occur after a period of time, which is very harmful. This time, stress occurs due to the difference of thermal shrinkage coefficients between metal and resin, and as time goes on, the stress exceeds the strength of gradually deteriorating resin data and cracks occur. In order to prevent the resulting cracks, as an experience, wall thickness 7 "and the external diameter of embedded metal parts 3, wrinkles and hemp surface
发生这种缺陷的缘由在实质上与充填缺乏相反,只是水平不同。因而,处理办法也与上述办法根本相反。特别是对活动性较差的树脂(如聚甲醛、PMMA树脂、聚碳酸酯及PP树脂等)更需求留意适当增大浇口和适当的注射工夫。
The reason for this defect is essentially opposite to the lack of filling, but at different levels. As a result, the treatment is fundamentally opposite to the above-mentioned approach. Especially for the resins with poor activity (such as polyformaldehyde, PMMA resin, polycarbonate and PP resin), more attention should be paid to increasing the gate and proper injection time.
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This article is provided by Jinan Liqiang Mould Co., Ltd. http://www.sdlqmj.com. Want to know more about Jinan Injection Mold. Welcome to pay attention to us, thank you!!

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