The pressure regulation and metering system is on the hydraulic injection molding machine, and all movements are performed by the oil circuit responsible for the following operations:<\/p>\n\n\n\n
Screw rotation in the plasticizing stage.<\/p>\n\n\n\n
Slide block chute (nozzle close to nozzle bushing)<\/p>\n\n\n\n
Axial movement of injection screw during injection and pressure holding<\/p>\n\n\n\n
Close the base material on the ejector rod until the elbow rod is fully extended or the piston clamping stroke is completed.<\/p>\n\n\n\n
Activate the assembly ejector rod to eject the component<\/p>\n\n\n\n
On the full electric press, all movements are performed by a brushless synchronous motor equipped with a permanent Jiu magnet. Through the ball bearing screw, which has been used in the machine tool industry, the rotary motion is transformed into linear motion. The efficiency of the whole process depends in part on the plasticizing process, in which the screw plays a key role.<\/p>\n\n\n\n
The screw must ensure that the material is melted and homogenized. This process can be adjusted by back pressure to avoid overheating. The mixing element shall not produce too high flow rate, otherwise it will lead to polymer degradation.<\/p>\n\n\n\n
Each polymer has a different flow rate. If this limit is exceeded, the molecules will stretch and the polymer main chain will break. However, the focus is still on controlling the forward axial movement of the screw during injection and pressure holding. The subsequent cooling process, including internal stress, tolerance and warpage, is very important to ensure production. All this is determined by the quality of the die, especially when optimizing the cooling channel and ensuring effective closed-loop temperature regulation. The system is completely independent and will not interfere with mechanical adjustment.<\/p>\n\n\n\n
Die movements such as die closing and ejection must be accurate and efficient. Velocity distribution curves are usually used to ensure accurate proximity of moving parts. The contact maintenance force is adjustable. Therefore, it can be concluded that without considering energy consumption, mechanical reliability and the same additional conditions (such as die quality), the output mainly depends on the system controlling the forward movement stage of the screw. On the hydraulic injection molding machine, this adjustment is realized by detecting the oil pressure.<\/p>\n\n\n\n
Specifically, the oil pressure activates a set of valves through the control board, and the fluid acts through the manipulator, and is regulated and released.<\/p>\n\n\n\n
Injection speed control includes open-loop control, semi closed-loop control and closed-loop control. The open-loop system relies on a common proportional valve. Proportional tension is applied to the required proportion of fluid, so that the fluid generates pressure in the syringe barrel and makes the injection screw move at a certain forward speed.<\/p>\n\n\n\n
The semi closed-loop system adopts closed-loop proportional valve. The loop is closed at the position of the closing port, which controls the flow proportion of oil by moving in the valve. The closed-loop system is closed at the screw translation speed. A speed sensor (usually potentiometer type) is used in the closed-loop system to detect the tension drop regularly. The oil flowing out of the proportional valve can compensate the speed deviation through adjustment.<\/p>\n\n\n\n
Closed loop control relies on electronic components integrated with machines. Closed loop pressure control can ensure uniform pressure in injection and pressure holding stages and uniform back pressure in each cycle. The detected pressure value is adjusted by the comparison valve, and the deviation is compensated according to the set pressure value.<\/p>\n\n\n\n
In general, the hydraulic pressure can be monitored. However, detecting the melt pressure in the nozzle or cavity is another effective method. A more reliable solution is to manage by reading the nozzle or cavity pressure readings. Adding temperature detection on the basis of pressure detection is particularly beneficial to process management.<\/p>\n\n\n\n
Understanding the actual pressure that the material can bear is also helpful to predict the actual weight and size of the molded part according to the set pressure and temperature conditions. In fact, by changing the holding pressure value, more materials can be introduced into the mold cavity to reduce part shrinkage and meet the design tolerance (including preset injection shrinkage). Near the melting condition, the semicrystalline polymer shows a great change in specific volume. In this regard, the overcharge mold will not hinder the ejection of parts.<\/p>\n\n\n\n The mold temperature af…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"aside","meta":{"footnotes":""},"categories":[1],"tags":[143],"class_list":["post-500","post","type-post","status-publish","format-aside","hentry","category-technical","tag-injection-molding-process","post_format-post-format-aside"],"_links":{"self":[{"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/posts\/500","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/comments?post=500"}],"version-history":[{"count":1,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/posts\/500\/revisions"}],"predecessor-version":[{"id":502,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/posts\/500\/revisions\/502"}],"wp:attachment":[{"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/media?parent=500"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/categories?post=500"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/tags?post=500"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/www.fuhrung.com\/technical-blog\/wp-content\/uploads\/2022\/04\/0414.jpg\")
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