Thermoplastic injection molding process technology

This approach thermoplastic injection molding plastic material that is melted and then injected into the film chamber. Once the molten plastic into the mold, it will be cold by the cavity-like shape into a certain shape.
Income is often the final shape of the finished product, as the final product is installed or no longer needed before using other processing. Many details, such as the Ministry raised. Rib, screw, can be injection molded in the molding step out.http://www.prmindustry.com/
Abstract...Articles section Injection molding machine has two basic parts: for anyone to melt the plastic mold and injection device and clamping device. Clamping unit's role is to: (1) the injection mold to withstand the pressure in the case of closure; (2) products out.
Plastic injection mold injection device prior to melting, and then control the pressure and velocity will melt into the mold. Currently used in the injection device has two designs: the pre-plasticizing screw, or two-stage device, and reciprocating screw. Pre-plasticizing screw device using pre-plasticizing screw (first class) and then given away the molten plastic material injection bar (second level).
Pre-plasticizing screw device has the advantage of melt quality constant, high pressure and high-speed and precise injection volume control (using both ends of the piston stroke of the mechanical thrust device). These strengths is the transparent, thin-walled products and high production rate required. Its drawbacks include uneven residence time (leading to material degradation), high equipment costs and maintenance costs.
The most commonly used reciprocating screw injection unit is about to plastic without melting and injection plunger. The hopper of the powder or granular plastic melt through the rotating screw to screw non-return between the front office, plastic front and accumulation of fluid flow through the screw in the screw in front. Screw the front of the accumulation of molten plastic into the injection device to the rear screw, screw rotation, the accumulation of melt and move back until the Department of a certain amount of injection. Equipment work the next cycle, the non-return screw tip to ask closed to prevent the material along the screw back. Feed screw tip and screw the role of material like injection plunger, the pressure on people to mold plastic.
Reciprocating screw benefits include reducing the residence time of plastic, self-cleaning screw and screw tip. These advantages in the processing heat-sensitive material and when used with a variety of color changes in raw materials or resins, the screw and the barrel should clean up, is the key.
The widely used clamping device design including: toggle clamping device, hydraulic and hydraulic clamping device has a mechanical clamping device. Toggle clamping device design in view of its low cost of manufacture, for a small tonnage of equipment. Features include high mechanical efficiency of blocking operations, equipped with clamping devices slow down, slow and fast mold damage mold operation.
Clamping cylinder to cross into the roof before the plate forward and make even the elbow extension movement. Clamping device is closed, mechanical advantage to reduce, to promote the rapid plate movement. When the plate reaches the mold closed position, with elbow high and one low mechanical advantage from the low to a high mechanical advantage. Low is critical to protect the mold, and high mechanical advantage is the formation of large tonnage needed once fully extended with ribs, hydraulic no longer necessary to keep the tonnage up. To open the clamping device, the hydraulic plunger imposed on the opposite side of the mold, forming a good product to prevent damaged, slowly open the mold. Even by the elbow, and plate device for mobile devices along the pull bar of the mobile (moving with the elbow fully extended device before the mold is closed at the opening), to adjust the clamping device to accommodate different mold heights. Toggle clamping device benefits include: quick clamping operation, reduce energy consumption and lower equipment costs. Disadvantage is that compared to hydraulic clamping mold complex, often connected to pin and bushing repair. However, the development of the elbow lever design has reduced the toggle clamping device maintenance, these developments, including oil bushing, greatly reducing the mandatory lubrication.
Progress of all the motor is one of precision ball screw machine tools currently available technology and advanced combination of AC servo motor to replace the hydraulic power unit. The motor only needs to complete the power plant functions, which greatly reduces the production of each product's total energy consumption.
Hydraulic clamping devices are widely used 150-1000t of equipment, and most used 250-700t of the device. With the pressurized tube (or external fuel tanks) quickly mold, a lot of oil in a small area on the role of the result is a very fast speed. Intended to ask the oil from the fluid reservoir with high gravity back into the main piston. Flap model in contact with two and a half ago, the mold should be at the low voltage protection status, this state prevents foreign objects, or flash out of the last cycle the products are not caused injury. When the mold is closed, shut down the priming solution Q pre-reservoir leading to the exit. The rear of the main piston-ton clamping force generated. The injection cycle, pre-filled open question, to promote mold clamping device gradually open valve. In a short distance, clamping device to accelerate the speed to quickly open.
Hydraulic clamping device for the installation and operation of equipment to provide flexibility. Because mold can travel in any part of the produce-ton clamping force, so long as the control of the device transferred to the corresponding position in the two halves in contact at the valve can be connected to the mold. Hydro-mechanical clamping device combines the functions of both mechanical and hydraulic clamping device to move and cause-ton clamping force. Due to the mechanical design of hydraulic filling between the flow limitation is to made into clamping device, are about to larger from 1000t. Clamping device is subject to the priming speed control fluid flow to ask. Hydraulic mechanical design include the following elements: the movable die plate to move to two and a half flap, almost touch each other's premises with the hydraulic cylinder; (2) prevent the formation of large tonnage clamping force moving backwards when the mechanical lock plate; (3) Finally, some distance to move the mold closed state and generates clamping force used by the short stroke hydraulic cylinder.
Coordination of all parts of the machine control machine functions. Has progressed to a multi-computer control system. And a control device in order to match the new, hydraulic machinery parts has improved. And servo control valve and the corresponding ratio of the amplification device to increase flexibility and accuracy, while reducing response time of the machine functions. The proportion of computer control systems and servo hydraulics to provide dynamic response in order to complete a true closed-loop system. Closed-loop system to compensate for oil temperature regulation machinery, raw materials and machinery variable viscosity changes. High level of control also appears in the auxiliary device. (Dryers, coolers and mold temperature control device), and that all equipment be adjusted by the CRT and LCD set and monitored. Connecting the main computer to provide a variety of machines throughout the plant monitoring and production scheduling, SPC at the machine or the host computer to provide real-time monitoring.
Plastics Processing important factors include: temperature, consistency, pigment distribution and density of the melt. Barrel temperature and screw the heat conduction resulting from the mechanical rotation produces both heat helps melt processing of high quality. The most common situation is that most of the energy used to melt plastic, obtained by turning the screw.
Mixing with the screw rotation between the threads, the surface of the plastic pellets are melted plastics. When the material along the screw forward, the repeated mixing and shearing until the plastic is completely melted.

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            Peter Huang