Requirements and technical difficulties of optical

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Requirements and technical difficulties of optical disc injection molding machine

recently, I heard from Guangdong Hongli 4 Press the "start" button to start the "Green Plan" button with 32 logistics partners around the world. The precision injection molding machine of optical disc substrate, the most key equipment in the optical disc production line successfully developed by the machine Co., Ltd. through independent innovation, has obtained the reply on agreeing to purchase domestic optical disc production line (Xin Chu Yin [2005] No. 1167) from the General Administration of publishing of the people's Republic of China. In the reply, it has agreed to sell the first domestic optical disc production line, The significance of this "

birth certificate" is unusual. People often measure the precision of precision injection molding machines by whether they can produce qualified plastic optical disc substrates. Therefore, the production of optical disc substrates has become the symbol of the top technology of precision injection molding machines. Therefore, the CD-ROM injection molding machine independently developed and officially put into the market by Guangdong Hongli Machine Co., Ltd. is an epoch-making event and milestone in China's injection molding machine industry, marking that China's injection molding machine has entered the era of precision and ultra precision

why can the level of precision molding of injection molding machine be measured by whether qualified optical disc substrate can be injected? This is determined by the shape and performance requirements of the optical disc substrate. The optical disc is used to store 3 a large amount of subtle information to speed up the research and development of the plastic machine. Therefore, a large number of high-precision grooves should be engraved on the substrate of the optical disc to store information symbols. The dimensional accuracy of the grooves reaches the nanometer level (the depth is only 0.11) μ The groove of M is made by injection molding with an injection molding machine), so it puts forward high requirements for the accuracy, quality uniformity and stability of the substrate; The shape and size of the optical disc substrate determine the difficulty in the forming process. The outer diameter of the substrate is 120mm or 80mm, while the thickness is less than 1.2mm, which means that the flow ratio of the flow channel in the mold cavity (the ratio of the flow to the depth of the flow channel) is very large, and the quality of the products filled and molded by the plastic melt is not easy to be uniform. In addition, the substrate is disc-shaped, and the main bypass is located in the center of the disc. After the injected plastic melt enters the mold cavity, it must be pushed rapidly and evenly along all directions of 360 degrees of the circumference, In order to flow in an orderly radial direction to the disc edge, if the local flow rate is too fast, channeling or auxiliary flow occurs in the process, it will lead to the formation of internal stress in the local molecular orientation, or the uneven cooling speed of various parts of the substrate will also lead to the formation of internal stress, which will affect the uniformity of substrate quality. In addition, with the high requirements of production efficiency and reliability, an injection molding machine can inject and form such a thin-walled disc, It also meets the quality requirements of optical disc substrate, which shows that the structural design, control system and process conditions of this injection molding machine have met the requirements of precision injection molding machine, otherwise it is impossible to form such high-precision products

in addition, there are three key technical problems to be solved in precision injection molding:

① the control accuracy is within 0.015mm

② the dimensional accuracy of the product shall be controlled within 0.002mm in the thickness direction

③ the repetition accuracy of injection weight is controlled within 0.3%. The above three key technical problems are related to a series of related technologies, such as manufacturing technology, assembly technology and servo feedback closed-loop control technology. They are the integration of many top high-tech technologies such as optical, mechanical, electrical and hydraulic. For example, in the case of high-speed injection (1000mm/s), the mode and difficulty of closed-loop control are equivalent to the guidance of missile. The difficulty is embodied in: immediate response, short time and large inertia

in order to meet the above requirements, the system rigidity of the clamping mechanism of the injection molding machine must be reasonably matched with the rigidity of the mold to ensure that the deformation accuracy and positioning accuracy are within the controlled range. The injection molding parts must ensure the plasticizing quality and high-speed plasticizing ability of the PC melt, and the melt temperature should be uniform to prevent the deformation of the optical disc caused by thermal stress. Therefore, the structure of the injection screw, nozzle and mold flow channel should be carefully designed, Geometry and dimensions. The electro-hydraulic integration system of the injection molding machine must ensure sensitive and accurate control and adjustment of parameters such as pressure, speed, displacement, time and temperature, and establish a closed-loop control with signal detection and sensitive feedback. Otherwise, it is difficult to ensure the stable repetition accuracy of optical disc products in tens of millions of injection molding

at present, although there are many VCD and DVD production lines in China, they are all imported machines. This time, the optical disc precision injection molding machine manufactured by Guangdong Hongli Machine Co., Ltd. was officially put into the market, realizing the real "zero" breakthrough of domestic optical disc injection molding machine, which means that a history of completely relying on imported equipment to produce optical discs has been ended, and a new era of domestic optical disc injection molding machine replacing imported equipment has been born

in China, many older generation of scientific and technological workers have struggled for decades for China's precision molding machine industry. However, because precision injection molding machines involve cutting-edge technologies in optical, mechanical, electrical, hydraulic and other fields, China's original technology foundation is poor. The technology of most enterprises comes from introducing technology from Hong Kong and Taiwan or imitating products from Japan and Germany. Although some enterprises claimed to develop precision injection molding machines in the 1980s or early 1990s, But in fact, it is only the use of more advanced electronic control components and hydraulic components. The main reason for the slow development of precision injection molding machines in China is that many domestic manufacturers can only rely on the introduction of technology or imitation surveying and mapping, and have no ability to independently develop new products. Finally, it is found that the gap between China's plastic machine technology level and foreign advanced level is becoming larger and larger, even more than 20 years. Many enterprises can only produce products with low general accuracy requirements

Guangdong Hongli Machinery Co., Ltd. has been adhering to the production of full hydraulic injection molding machine for more than 10 years. It is a typical enterprise that has obtained patents from the United States and other countries and transformed into productivity. All its products and technical bases are independently developed and have independent intellectual property rights. It is extremely rare for technology-based enterprises to make such a big breakthrough in precision injection molding

source: International Plastics Industry


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