【導(dǎo)讀】我們?nèi)粘Ｉa(chǎn)、生活中所使用到的各種工具和產(chǎn)品，大到機(jī)床的底座、機(jī)身外殼，小到一個胚頭螺絲、紐扣以及各種家用電器的外殼，無不與模具有著密切的關(guān)系。的形狀決定著這些產(chǎn)品的外形，模具的加工質(zhì)量與精度也就決定著這些產(chǎn)品的質(zhì)量。近年來，隨著射料工業(yè)的飛速發(fā)展和通用與工程。一個設(shè)計合理的射料件往往能代替多個傳統(tǒng)金屬件。化的趨勢不斷上升。屬材料制出所需形狀的零件或制品，這種專用工具統(tǒng)稱為模具。該方法適用于全部熱射性射料和部分熱。場競爭中的反應(yīng)能力和速度。注射模具是由若干塊鋼板配合各種零件組成的，基本。組零件部分構(gòu)成，這個組合內(nèi)有成型模腔。模具中冷卻的原則是產(chǎn)品要在模具中冷卻和凝固,以便隨后可以。按照習(xí)慣，腔空間的中空部分稱為型腔。這兩個板分離時的部分叫做分模線,簡稱P/L。計在同一個平面上。為了能夠在模具上脫出產(chǎn)品,分模線總是在分布在產(chǎn)品最

　　

【正文】 ine marks left which would tend to retain the runner in the mould the gates which are small openings leading from the runner into the cavity space. The gate is a channel or orifice connecting the runner with the impression. It has a small crosssectional area when pared with the rest of the feed system. The gate freezes soon after the impression is filled so that the injection plunger can be withdrawn without the probability of void being created in the molding by suckback. 4. The injection molding machine process Injection Mold is installed in the injection molding machine, and its injection molding process is pleted by the injection molding machine. Following is the injection molding machine molding machine uses a vacuum to move the plastic from the dryer to it39。s initial holding chamber. This chamber is actually a small hopper on the back of the barrel of the machine。 The barrel is where all the real work is done and it39。s essentially a large screw housed in a heater which moves the plastic closer to the mold. As the screw turns, the plastic traverses the barrel and reaches a molten state. Only when it39。s molten can it be injected into the mold with a rapid turn of the screw. As the chamber in front of the screw bees filled, it forces the screw back, tripping a limit switch that activates a hydraulic cylinder that forces the screw forward and injects the fluid plastic into the closed mold. The gate freezes soon after the impression is filled so that the injection plunger can be withdrawn without the probability of void being created in the molding by suckback. The tip of the barrel is called the nozzle and from this point to the cavity in the mold the material is not heated and is constantly cooling. The runner is the cooled/set plastic that extends from the nozzle to the cavity and is process scrap. Actually, the cooled material from the nozzle to the mold is the sprue but it39。s connected to the runner. There are ways around having sprues and runners, but it39。s beyond the scope of what we39。re talking about here. Most people have probably seen runners before and not realized it. The most likely place to see them are in model airplane/car kits as the individual ponents are left attached to the runner system. Typically the runners are ejected into a chute below the mold or else they will be picked out of the mold by a robotic arm and dumped into a regrinder. The regrinder chops the runners into bits and prepares them to be moved back into the dryer. Though, once plastic has been heated, it degrades a bit and some molding processes will 10 not allow for regrind to be mixed back in with virgin material as it can cause problems with the final part. In cases like this the regrind is used elsewhere or it is discarded pletely. Shrinkage plays a crucial role in molding and most plastic shrinks 20% as it cools. In order to bat this phenomenon in critical plastic pieces (not really toys) it is up the mold designer to build this factor into his design so that the finished parts will meet the original product design specifications. Ejector pins are part of the mold itself and are used to push the molded parts from the cavity once the mold is opened. This ejecting process is controlled by the molding machine. The molding cycle is basically close shoot open eject. The mold is clamped into the machine with the front half remaining stationary (on the barrel side of the machine) and the back half being the movable half. Also on this movable half are the ejector pins that push the molded parts from the cavity. The parting surfaces of a mould are those portion of both mould plates, adjacent to the impressions, which butt together to form a seal and prevent the loss of plastic material from the all molds open up, the parts are stuck to the back half of the mold so that they can be ejected with the builtin pins. These are related to the introduction of the injection mold.