Nissei Developed a Specialized Electric Molding Machine for Large-Sized Light Guide Plates
Nissei Plastic Industrial Co., Ltd. has recently developed a specialized electric injection molding machine for large-sized light guide plates and a special mold, which are exclusively used for liquid crystal displays. Light guide plates are the parts which are used inside of a back light unit (lighting equipment) that leads the light to liquid crystals in a liquid crystal display (LCD). At present, they are widely used for small-sized (1 - 8 inches) products such as mobile phones and car-navigation units, and also for large-sized (9 - 15 inches) products including notebook-sized personal computers. With the expansion of its uses in future, special processing of surface shapes (gradation and others), reduction of weight (to make thickness of plates thinner), high precision and high quality are being required. Nissei has been handling hydraulic type molding machines exclusive use for light guide plates up until now. Based on its technical know-how so far accumulated, it has newly developed a specialized electric molding machine, along with a special mold, which is important and key to maintain precision of products. The newly developed electric machine has a mold clamping force of 460 tons (4508 kN), which is the biggest among our electric machines and best suited to the molding of light guide plates (12 - 15 inches) for large notebook-sized personal computer use, and injection volume of 403 cm3. Furthermore, it can be said the largest clamping force in the industry as machine, specific use of light guide plates of notebook-sized personal computer. In regard to the molding of large-sized light guide plates of 14 - 15 inches with a mirror-surface finish, which are used for liquid crystal displays of notebook-sized personal computers, the molding time has been required from 50 to 70 seconds until now. This machine can mold the light guide plates mentioned above with a high cycle of less than 30 seconds as the crucial advantage of the machine. This molding machine has the following technical advantages, especially in order to materialize improvement of the quality of light guide plates: (1) A center driving system, for which a ball-screw and a servomotor are directly connected to a driving servomotor, is used for the injection mechanism and the mold clamping mechanism. (2) By means of the original designing of a screw, quality of materials of a barrel, a shape and a temperature control system, molding materials (resins) can be kept under the optimum conditions, so the uniformity of products is materialized. (3) Internal strain of large-sized light guide plates is reduced through improving the stability in the low speed and high speed ranges at injection filling. (4) Using an original mold clamping compression mechanism, it demonstrates high transferability with precision control through quick responsivity. Furthermore, it displays the energy-saving effect of 35 - 60% more than hydraulic molding machines. Moreover, as a specialized molding machine for light guide plates, original devices are made for the injection mechanism and the mold clamping mechanism. Regarding the injection mechanism;
Regarding the mold clamping mechanism;
Moreover, this machine ensures the molding of large-sized light guide plates from 12 inches to 15 inches corresponding to molds. Furthermore, it can work with shapes of sections such as a wedge-shape and a flat shape, gradation processing (dots, patterns of V-shaped grooves) of one side and both sides of surface shapes. Main specifications of the specialized machine for light guide plates:
[Note 2] SSR: Solid state relay. A contactless relay using a semiconductor.
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