Injection molding machine with once forming complex, precise size and shape with plastic metal insert is dense, is widely used in national defense, electrical, automotive, transportation, building materials, packaging, agriculture, education and health care and daily life of people in various fields. Injection molding process of a plastic has good adaptability, high production capacity, and easy to realize automation. In the plastic industry is developing rapidly today, injection molding machine plays an important role both in quantity or variety, its total production accounted for the entire plastic molding equipment of 20%--30%, thus becoming the fastest growth in plastics machinery, one of the largest number of production model. According to statistics, 1996--1998 years, China's export of injection molding machine 8383 Taiwan (sets), imports of injection molding machine 42959 Taiwan (sets), which in 1998 China injection molding machine production reached 20000 units, its sales accounted for 42.9% of total sales of plastic machine. The working principle and the injection syringe injection molding machine with similar, it is through the use of screw (or piston) thrust, will have good plasticization molten state (i.e., the viscous flow) injection into die cavity closed good, cured after finalizing the design process of products made. Injection molding is a cyclical process, each cycle includes: quantitative feeding - plastification - pressure injection - mold filling cooling - opening mould to take. Remove the plastic piece again after closed die, for the next cycle. Injection molding is a cyclical process, each cycle includes: quantitative feeding - plastification - pressure injection - mold filling cooling - opening mould to take. Remove the plastic piece again after closed die, for the next cycle.
General injection molding machine which comprises an injection device, clamping device, hydraulic system and electrical control system etc.
Injection device: its main function is to make the plastic uniform plasticizing into molten state, and with enough pressure and speed will melt is injected into the mould in. It is mainly composed of a plasticizing component (barrel, screw or plunger, nozzle etc.), hopper, screw driving device (motor oil, etc.), the injection cylinder injection seat moves cylinder etc..
Clamping device: it is to ensure and realize the closed mold reliable opening and closing action and withdrawing the product parts mould. Because the melt at high pressure is injected into the cavity, in order to lock the mould without making the product produce flash or affect the quality of the products, will be applied to the mold locking force is enough (i.e. clamping force). Mold closing device mainly comprises a fixed template, template, the rear wallboard, mobile connecting rod, before and after the template with the mold closing cylinder, the push out oil cylinder mould adjusting device, etc..
The hydraulic system and electrical control system: it is the guarantee of the injection molding machine according to the process of predetermined requirements (such as pressure, velocity, temperature, time) and action program is accurate and effective work and set up the power and control system.
The molding process of the general screw injection machine is: first the granular or powdered plastic join the machine barrel, and through the rotation of the screw and barrel outer wall heating so that the plastic as a molten state, then the machine clamping and injection seat moves forward, so that the nozzle tightly mold pouring mouth, then to Walter injection cylinder pressure oil, so that the screw forward, thus at a high pressure and speed will melt into the closed mold temperature lower, after a certain time and pressure maintaining (also called holding pressure), cooling, make its curing molding, mold products can be removed (holding pressure to prevent melting reflux, supplementary material to the mold cavity, and the assurance of products with certain density and dimensional tolerances in the mold cavity). Injection molding plastics is a basic requirement, and injection molding. Plasticizing is realized and the premise to ensure the quality of molding products, and to meet the requirements of molding, injection must ensure that sufficient pressure and speed. At the same time, the injection pressure is high, corresponding to a high pressure is generated in the cavity (the average pressure in the mold cavity between 20~45MPa in general), so there must be a big enough clamping force. Thus, an injection device and a molding device is the key component of injection molding machine.
Injection molding machine action program
Close the door, mold, injection, holding pressure and nozzle forward to pre plastic, loosening, nozzle back to cooling, die opening, ejector, withdrawing the needle to open the door.
Injection molding machine operating items: control keyboard operation, electrical operation of the control system and hydraulic system operation three aspects including the operating project of injection molding machine. Injection was performed, the feeding process action action, injection pressure, injection speed, ejector type selection, monitoring the temperature of barrel, injection pressure and back pressure regulator etc.
Evaluation of plastic products mainly has three aspects, the first is the appearance of quality, including integrity, color, luster; second is the accuracy of size and relative position between; third is physical properties, and use the corresponding chemical properties, electrical properties. These quality requirements and articles according to the use of different occasions, different requirements of scales. Product defects mainly lie in manufacturing mold design, precision and degree of wear etc.. But in fact, personnel of technology of plastics processing plants often suffer from a face with the technology means to compensate for the mold defects due to the difficult situation of the problem and the effectiveness of small.
Regulation of the production process is the necessary way to enhance the product quality and yield. As the injection cycle itself is very short, if the process conditions is not well controlled, the waste will flow like water. In the adjustment process of the best time to change only one condition, more observation several times, if the pressure, temperature, time all together the tune, very easy to cause confusion and misunderstanding, wrong