Sequential valve control technology of the hottest

2022-10-16
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The sequential valve control technology of plastic mold

sequential valve control technology (SVG Technology) is gradually replacing the traditional valve control and becoming the manufacturing method of the most difficult parts

svg technology will replace the traditional valve control technology

at present, in automotive and other industries, large plastic parts with complex structures are difficult to manufacture, because in the production, it is easy to produce problems such as accumulation, warpage and splashing, which is difficult to meet the more stringent requirements for surface quality

it is difficult to solve the above problems by using the traditional valve control hot runner system. In the traditional valve controlled hot runner system, opening or closing all valves at the same time will inevitably affect the control of problems such as welding or tight wiring, gas valves, local accumulation and unstable flow. Fortunately, at present, a technology called sequential valve control (SVG) can control the above problems at any time. Although it is not a new technology to introduce programmable timing into the process of valve opening or closing, this method helps people solve the above problems

for example, when one mold groove is of complex geometry and the shape of the other mold groove is relatively simple, or a multi runner part is of irregular shape or some parts are of different thickness and have edges, bosses or joints, the forming process is very difficult. In this case, if the forming process of the traditional valve control system is adopted, some parts of the parts need to be tightly stacked so that other spaces can be completely filled. These tightly stacked parts not only waste raw materials, but also easily cause problems such as sticking, warping and stress freezing

in the process of continuous painting operation, local stress will cause oblique cutting or paint over sticking. Further, in case of over tight accumulation, a more solid press should be used to obtain a larger injection unit and achieve high level fixation

injecting raw materials from multiple channels at the same time may also cause problems for other decoration steps, including delamination (or post molding) in the mold cavity. If the flow in the injection process is unbalanced, the fibers or films embedded in the tool may fold or fold

for parts with multi sprue single mold cavity, the position and appearance of weld line are very important. If the weld line appears in the critical stress area, the integrity and performance of the part will be damaged. At the same time, the weld line produced by the multi runner can still be seen even after painting

according to Mr. Kurt Weiss, manager of GE Plastics' component performance and new material introduction, the bonding line on the colored parts will cause obvious visual defects, while for glass filled products, the bonding line will have a negative impact on both aesthetics and performance. He said that many methods have been tried, including adding slides into the mold to control the high cost of injection. Mr. Harald Schmidt, head of MHS (mold hotrunner solutions), also said: "many molding workers try to control injection by limiting nozzle holes and spray channels to reduce problems such as too tight accumulation, stress and weld lines. However, a smaller nozzle will lead to excessive melt shear." He also said that people cannot change the viscosity, pressure and temperature of materials. However, through SVG method, even if the material or environment changes, molding workers can obtain high-quality parts by controlling the injection mode of the mold cavity

Murali annareddy, the production line manager of Moldflow, a molding simulation software supplier, believes that it may be a better method to transfer the position of the bonding line by adjusting the size of the flow channel rather than the size of the valve. He said, "this technology of manually adjusting and balancing flow is very suitable for multi cavity mold. For this reason, Moldflow provides an automatic flow balancing program to adjust the size of the runner. However, such an approach may still lead to different shear forces in the melting process, affecting the quality of parts." Annareddy also warned that another risk is stagnation in smaller flow channels, and the manually adjusted flow rate system is more sensitive to changes in processing equipment

in the past, when making high-precision parts, such problems forced some molding workers to abandon the use of multi-channel or multi-mode cavity molding methods, because these methods are really difficult to produce uniform and accurate parts

advantages of SVG method

after 10 years of practical application, SVG Technology has gradually been recognized as an alternative to traditional valve control and thermal control. Svg technology has obvious advantages in controlling the junction line. It can transfer the junction line to non critical areas or even outside the exit. The timing of the valve also enables the multi cavity mold to be evenly injected, which has been widely concerned by the industry, eliminating the phenomenon of over tight accumulation and splashing. At the same time, the damaged cavity in the multi cavity model can be isolated without taking out the whole casting. Neil dewar, production engineer of mold masters, said that molding workers can adjust and balance the injection process by using valves without adjusting the flow channel and other more. This kind of algae is a kind of size with more renewable resources

manufacturers also listed other advantages, such as: compared with the method of injecting from multiple sprues at the same time, sequential injection from multiple sprues can reduce the tonnage of the fixture by 20% to 30%. In addition, the manufactured parts can maintain high accuracy in packaging and storage, and can withstand long-term high-strength extrusion during transportation to the destination

at present, there are at least 8 hot runner technology suppliers that can provide SVG Technology, including D-M-E, INCOE, husky, MHS, mold masters, osco systems, p.e.t.s and Synventive. It is said that these eight companies have set up dozens to hundreds of SVG systems

technology is used to make auto parts

SVG Technology is mainly used to make auto parts, especially some large parts such as buffer, baffle, tire liner, rocker slat, grille, exhaust fan, radiator, suction system and instrument panel

in addition, optical parts such as lenses are also used in the field

svg technology opens the way for the application of valve control means in the frontier automation field, such applications include: internal mold lamination, embedded film modification, CO injection, soft hard multi material molding, gas assisted and long glass fiber composites. Mr. mark moss, head of sales, marketing and R & D of Synventive, said, "at present, the co injection molded parts of TPO automotive buffers have not yet formed a large market, but this market is in the process of successful development." With a pollution-free shell and recycling inside, it will release enough productivity and creativity to change the industry! The continuous molding of nuclear TPO buffer helps automobile manufacturers meet the growing requirements for "green" vehicles. For such parts, it is impossible to form them with traditional valve control system

generally, most of the molding workers of auto parts hate the process of painting. In this regard, suppliers suggest that decorative film clip molding products be used to replace externally painted parts such as door panels, and SVG Technology has played an important role in the development of this product

osco systems, which claims to have invented SVG Technology, used SVG for the first time to solve the covering problem of automotive parts. Mr. Peter rebholz, the company's head of sales, said, "at least 10 years ago, we had made many molds for GM's truck and car grille, and we encountered the problem of joint line at that time. We applied SVG Technology to transfer the joint line from a smooth place to the edge." He also said, "at the same time, we began to study the internal mold decoration. Using SVG Technology, plastic can be drawn into the mold without degrading or blowing out the devices in the mold. We also used SVG Technology in multi cavity mold, and the container and its packaging cover can be made in one mold cavity."

Mr. Dewar of mold Masters said: "After 10 to 15 years of development, people have applied SVG Technology to the production of products such as TV back covers. This technology enables molding workers to produce large parts that do not need painting. At the same time, this technology has also been applied to 30% glass fiber filled nylon car covers. The application of svg technology solves the problems of damage to the surface of parts and the impact on the structure of parts caused by bonding wires."

according to Mr. mark nietzke, the interior decoration development project manager of Collins & Aikman of Troy, Mich., they are applying SVG Technology to the project of in mold layering. "Using SVG system, the injection process in the mold cavity can be controlled, and it helps to reduce the pressure on the vinyl inserts wrapped in foam during the injection process." Previously, shapers in the engineering plastic products Department of Owasso, Mich. used p.e.t.s.'s SVG system to produce 16 × 20 inch polypropylene parts, which are injection molded and then packaged with foam alkene coating. Mr. mark nietzke said that Collins & Aikman will soon start another SVG project, which is to make vinyl coated door panels for GM's epsilon car. Among the four models required by the project, three have been built and confirmed to be available for production, and the fiber coated instrument panel made of SVG is being considered as the model of 2006 ~ 2007. In addition, Collins & Aikman also used SVG Technology to make seat backs for Visteon

among the parts made by SVG Technology, one of the most characteristic parts is the two-component weatherstrip on Ford F150 pickup truck. According to Mr. innatech, an injection molding worker of Rochester, Mich., who specializes in multi-step injection operations, it is estimated that 14million such parts will be molded every year. It is reported that in the molding of parts, the first injection material is polypropylene filled with 20% talc powder, and the second injection material is soft Santoprene TPV containing silicone lubricant generated in the rotating mold. Only the edge seal of TPV uses SVG Technology. During molding, raw materials are gradually injected from the center of the five sprues to eliminate defects such as runner defects, joint lines, and air pockets. All runners are set in the temperature range of 30 ° ~ 45 ° to avoid sprue defects. In addition, Mr. innatech also designed a PLC processing control system, which discretely controls each valve in multiple steps through the set screws representing the pressure during the injection cycle. This thin weatherstrip is 38 inches long and swings between the front and rear side doors, combining the functions of noise reduction, weather protection and joint cover. It is said that this part won the qualification to enter the finals in this year's SPE automotive plastics Innovation Award

improving the shape is the main reason for applying SVG Technology, but it is not the only reason. According to Mr. Kevin golden, the production manager of husky company, husky company once produced a 1500mm long anti impact shock absorber for automobile dashboard. Using SVG Technology, the tonnage of the fixture was reduced by nearly 30%. He said, "our components are mainly used to manufacture a large number of automotive grilles, most of which are completed by SVG Technology."

in fact, as early as 1995, the leaders in the auto parts industry have adopted SVG Technology. Among them, nascote company in Navier, Illinois uses GE's Xenoy polycarbonate/polyester resin to produce buffers, which reduces the production cycle from 110s to less than 75s. In fact, the time savings are mainly due to the application of SVG Technology, which reduces the cost of

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