Several new structures of the hottest injection mo

Several new structures of injection molding molds

plastic products are increasingly used in automotive, electronics, military, communications, home appliances and other industries, and people's quality requirements are also constantly improving. With the continuous success of the research and development of various new materials and new technologies, as the core component of product molding, the mold must adapt to the processing needs of new materials and new technologies. Mold manufacturers can only have a place in the market if they constantly promote mold institutions and processing technology and hope to bring a certain help to everyone. In addition to meeting the special processing needs, the design of the new mold mechanism can also significantly improve the production efficiency, which has become one of the highlights of mold technology

mold "fast" heating and cooling system

for injection molding, the quality and efficiency of the cooling system are the key to the quality of a mold design. Designers often encounter the problem of how to choose the appropriate mold materials and design a reasonable cooling channel, so that the plastic can be cooled quickly and evenly in the mold cavity. Looking at the causes of surface defects of injection molded products, the weight of the large rear tailgate is 30% less than that of the metal tailgate Mr. remisalomon said that it was mostly related to the low mold wall temperature when the material was filled. For this reason, Nada has developed a "fast" heating and cooling system e-mold. The reason why it is called "fast" is that after using this system, the mold temperature can be heated to 300 ℃ in 15s, and then cooled to 20 ℃ in 15s

the traditional cooling method is made of carbon fiber composites, which usually indirectly realizes the cooling of the mold wall by cooling the template. The e-mold system puts forward a new design concept - directly controlling the temperature of the cavity surface and the forming template: when the mold is opened, heat the mold surface, reach the required heating temperature before the mold is closed, and stop heating, Make the mold temperature higher when filling the mold; After pressure maintaining, isolate the heat source to make the mold cool quickly. The high temperature of the mold during the filling process greatly improves the surface quality of the products

from the comparison in Figure 1, it can be seen that the use of e-mold technology not only eliminates the defects such as melting marks, flow marks, spray marks, crazing and shrinkage marks of the products, but also improves the consistency of the surface structure and gloss of the products, and reduces the deformation of the products. Compared with traditional processing methods, using mold technology with more than 4000 e-workers to rapidly cool the mold after pressure maintaining can significantly reduce the forming cycle of products and improve production efficiency. At the same time, the application of this system also provides convenience for the injection molding of ultra-thin, ultra thick and high filling material products

Figure 1 Comparison of surface quality between products molded with traditional cooling system (left) and products molded with "fast" heating and cooling system (right)

t-mold

laminated molding is a new highlight of injection molding technology in recent years. It can significantly improve equipment utilization and production efficiency, and help reduce production costs. It is commonly used in large flat parts, small multi cavity thin parts and parts requiring mass production. However, laminated molds are not often used in ordinary injection machines, because the molding process of all products in a mold is synchronous, with simultaneous injection and simultaneous mold opening and ejection, which increases the injection volume and mold moving stroke of the injection machine

Germany has developed a mold structure similar to the laminated mold - t-mold. Its structure is to install the molding molds of different products back-to-back like valve molds. However, its forming process is completely different from that of the laminated mold. The forming process of all products in the t-mold is independent, and each parting surface is opened alternately: when one side is cooled, the other side can be plasticized, opened, demoulded, closed, and can be filled and maintained again. In other words, with this mold, at any time, only one cavity in the parting surface is filled, and only one product on the parting surface is ejected. It seems that the whole molding cycle is the superposition of all product cycles. However, because the rapid injection machine can realize the parallel action of opening and closing the mold while plasticizing and ejecting, the time of opening and closing the mold and ejecting is saved, and the production efficiency is improved

in addition, in order to improve the application range of t-mold, the organization has successfully developed the technology of combining two sets of ordinary molds into one set of t-mold

converting ordinary molds into t-molds

when converting two sets of cold runner molds into one set of cold runner t-molds, regardless of the cost of conversion, two more important problems about the use of existing molds must be considered: first, how big will the overall size of the mold be? 2、 Which mold depends on the fixed plate

taking two sets of molds to produce the handle as an example, the process can be explained as follows. Both sets of molds are gas assisted injection, and the cycle of each set is 80 seconds

suppose that the larger mold has been running on the existing injection machine, as long as the thickness of the second set of mold is increased. When using a direct pressure mold locking injection machine, the maximum of the overall thickness of the mold plus the two mold opening strokes must be smaller than the maximum opening distance of the mold of the injection machine

by analyzing different types of dies, it can be seen that even dies with a thickness of more than 100 mm can be successfully converted to t-dies. First, you can cancel the two code templates; Second, the maximum opening distance of the template of most direct pressure injection machines can be increased by reducing the distance between the thrust plate and the ejector plate (canceling the ejector cylinder of the injection machine). This conversion therefore requires that the die be equipped with two side mounted ejector cylinders. The ejector plate of the die against the fixed plate must also be equipped with the ejector cylinder installed on the side

basically, the T-die is similar to the laminated die, that is, the ejector plates of both sets of dies are outward. This means that the molten rubber can be injected directly from the middle plate with the injection device placed behind the injection machine (opposite to the operator), or it can enter the normal center gate position through the hot runner. The first option is simple for the mold maker, but a special injection machine is needed. The second option usually requires a very special hot runner, but it can be used on standard injection machines

usually, on the laminated mold, the molten rubber is injected through the ejector plate of the fixed plate mold. This is also applied to the T-die in current production. Therefore, before converting the standard mold to t-mold, we must consider which side is easier to install the hot nozzle assembly

to be exact, it means that the fixed plate mold with small mold thickness and enough space for the hot runner of the injection surface will be used as the t-mold

as long as the above basic points are solved, there will be no problem with this conversion. First, remove the redundant code template. Both sets of molds are fixed on an adapter plate. This adapter plate well connects the two parts, including the guide rod and guide sleeve, and can ensure that the outflow of cooling water is blocked

integral hot runner system

hot runner technology, as an advanced technology of plastic injection mold, is increasingly being promoted and applied. However, the hot runner mold has complex structure, high cost, high maintenance cost, and is prone to melt leakage, heating element failure and other problems in the process of use, which seriously restricts the wide application of the hot runner system

in the integral hot runner system developed by INCOE company (as shown in Figure 2), bolts connect the standard hot runner plate and nozzle to form an integral hot runner structure, which avoids the misalignment between the hot runner plate and nozzle and the appearance of dead corners of the runner, thus preventing the leakage of melt between the two. Unlike the conventional hot runner system, which uses the locking and pre stretching of the template to realize the alignment with the template, the integrated thermal insulation support block of this structure can not only realize the alignment of the template, but also has a small contact area with the template, which reduces the heat loss and improves the temperature distribution curve

Figure 2 integrated hot runner system

"green" hot runner system

biodegradable plastics as a technical way to treat plastic waste, its application is not limited to agricultural mulch, packaging bags, garbage bags, tableware and other fields. Some computers and production enterprises have developed personal computers and, Some automobile manufacturers are committed to applying biodegradable plastics such as PLA to the research of future cars. In view of the poor physical properties of biodegradable plastic products, raw material suppliers have also introduced polylactic acid with a crystallization rate of about 100 times, which can produce high heat-resistant injection products at about 120 ℃

at present, the injection molding of biodegradable plastics is subject to processing and molding. Because most biodegradable plastics are heat sensitive materials and are easy to degrade to produce strong corrosive acids, the application of hot runner technology in the molding and processing of biodegradable plastics has been blank for many years