压塑和压铸工艺-外文文献

Plastic and pressure die casting processIn recent years, the pressure technique used in thermosetting plastic materialmixing ,such as urea-formaldehyde plastics, phenolic resin, epoxy rsin, melamineresin and rubber. In spite of some of the material can be injection moiding, but the use of plastic pressure process is still very common. More pressure die casting material used plastic materials require more malleable soft. Many thermosetting materials with high impact level (1.0ft-1b) and good impact strength of maintaining the gap, only under ertreme pressure will flow.Thermosetting plastic molding material pressure of the obvious advantages of the system is simple. Materials will be placed in a heating cavity, the pressure required by the Mission to time. As a result of the process simple, cost less. Enhancer and additive-free rules, and be able to get a better strength. As the gate and no runner ,not a waste of materials, die almost no maintenance. Parts of unity, and I cast no trace flow and reduce the cost of the modification. According to the structure and products used in the application of the characteristics of can be full-pressure die ,and die-pressure semi-closed mode (can be found in the plastic, plastic mold pressure related articles).Equipment: The pressure is a simple plastic deices the main features . platen combination of the two and a half , heating, pressure, the shape of the target material. Most of the process of plastic used hydraulic pressure to operate; also used pneumatic operation .Tow board up and down under pressure in the 4 corner posts on moving up and down. According to the plastic device the size of the pressure, the pressure is generally 20-1000 tons. The general board for the 8-inch size 2-5 feet 2.In addition, and after curing the release of different aspects of the degree of automation, the most commonly used modern hydraulic machine. The previous system , there is a simple temperature control, pressure control, pressure control and stop-time control. The use of modern equipment, advanced microprocessor control. For thinner products, in the board can be used in heating tube or belt heater. To the deeper parts, the need to use tube-shaped electric heater , heating steam or hot oil heating system. There are several types of plastic used in pressure in the heating system: uniform temperature steam heating mode, but the heating temperature is limited to below 350F;sleeve heating or other heating (heating coil, heating,ect.) relatively clean and easy maintenance, A more universal; thermal heating oil, heating due to the stability of the media cycle, the heat evenly. Now there are many new methods of heating ,hot water heating ,similar to the hot oil heating , water heating a medium for a gas combustion cycle , provides a greater degree of pressure temperature plastic.Polymer modified to enhance rapid industrial development requires a new pressure to improve the plastic industry . Enhanced by two molded plastic mold: mold-yang (side mode) and the negative mold (cavity). When the mold is full of reinforcements, the mode of the hot mold closed two and a half, and then heated, pressurized product to be cured. Along the lines of big changes in the complexity of the mold can be used aluminum, plastic or steel do.Light-weight materials making them less expensive, generally used for the production of short-term such as “cold-molding”.Coll at room temperature with molded resin, but the use of plastic mold and hydraulic pressure. The production of long-term use of hardened steel molds relatively cost-effective, the cut-off billet I can provide better performance and excellent cut finish. These steel pressure module on the use of machinery on the cut-off billet adapter I usually die together in the face area. This mode f metal molds, the products of its uniform surface, a good finish. Closed-mode technology used to pressure plastic molding,die-casting molding, injection and stamping some of the reinforced composites.Some of the thermoplastic plastic materials can be molded plastic pressure, but in general or with pre-mixing of thermosetting resins such as BMC (prefabricated molding as a whole),SMC(film forming material molding),TMC(thick molding),film forming, such as carpet.Carpet wet film forming sometimes called composite molding, in the hydraulic press will strengthen the role of materials and combined with resin. Often placed in the mold in carpet film will be dumped in to strengthen the resin material. Pressure in the process of cavity filled with resin to strengthen the material when fixed.If there are serious parts of the alien or gradient, it is necessary to carry out pre-forming. Most of the film and felt pre-forming system in the projected area of the states need to 150-200 pounds/2 inch of mold pressure.Pre-mixing materials, such as SMC, prepreg resin, filler, and the catalyst size enhance the material cut into a certain team sheet, and then adding the hot mold (in general 300-400 F), 1000-2000 1b/2 inch pressure Under the molding.SMC for the relatively new plastic devices the pressure of the total cycle may be less than one minute (from start to finish). Has developed a special hydraulic device back in the bowl pressure machine, automatic control of the board level degrees. Reinforced plastics, such as SMC, with a metal finish on molded plastic, tjis is very important parts of the surface. Sometimes occur in the processing of fibrous contraction.Model with coating method could improve the surface finish. BMC pressure of the process of plastic is the oldest pre-mixing after one of the molding process. Filling materials (wood, mineral materials, such as celluiose) are mixed in mixing the leaves in the shap of the mixer. Will feed into a group of 300400 F in the mold. In the 500-pound/2 inches under the pressure of molding. As a result of the use of materials for low-cost, the cost of raw materials. However, as in the molding process, the orientation of fiber reduces the mechanical strength.Plastic high-speed pressure, that is, enhanced thermoplastic stamping the sheet, a wide range of uses. Felt piece of glass and polypropylene can be used to match the plastic stamping, the cycle less than 40 seconds. Green sent to the convection heating furnace. Heating, rough pressure into plastic molds, in the process with new pressure machine machine speed up to 1400 inches/minute. To 75 inches/minute (SMC than the pressure of plastic process about 3 times as fast) feed pressure. According to the requirements of the market, some of the new stamping plastics, surface finish, and can be coated with nature. I metric ton of pressure on the general molding/2 inch. Traditional plastic pressure technology in recent years has been on the rise. In the space technology for national defense and the application of this technology is difficult to shock.In the SMC, BMC, TMC, the thermoplastic sheet stamping, reinforcement of the Blending plastic mechanical pressure and the development of the rapid growth of industry in order to meet the new requirements.A number of advanced materials mixing plastic pressure mainly in space technology and applications in the rapid development of national defense. Tools and dies and the new concept of high-temperature (up to 1200 F) molding machine to make a graphite carbon fiber composite materials can be developed to replace the existing metal castings.High temperature silicone is used as a high-pressure media. The composite sheet for the pressure in the mold. Now ,materials and production costs have made the process more suitable for space technology market, this type of silicone is also soon to the area of automobile.In the die-casting process, thermosetting resin material is expected to join a separate chamber, often called trough, and then forced into one or more closed modules for polymerization(curing).Liu, also known as Notes and the road runner, so that the flow of materials from the through cavity into the mold cavity before or after limiting gate. Many cavity with a single through. The air chamber is expected to be the replacement materials come in through a special place of the exhaust emissions.When the materials placed in the trough, in a compact measuring device detected charge, and then warm-up to close to the polymerization temperature. Only by adding a sufficient amount of time the injection.Preheat the raw materials will be sent trough of force and then a note sent to the feeder, the feeder note immediately installed in the trough, so as to prevent the pistons from the trough and gap between the edge of missing material. Taoka is usually closed to inject into the feeder to further leak-proof.Trough, the note feeder, gate, runner and mold cavity on the surface of the material can maintain the rapid solidification of a certain temperature,according to the nature of the materials, mold design and parts of the temperature of 280380 F.In the die-casting material to reach the end of the curing period, the second-casting for a complete release, including the removal gate, runner and injecting Road in trough and the formation of curing pad material (called salvage).In the die-casting, the warm-up material is very important. Cold expected to sloe the flow, first into the cavity of the material to its destination yet, that is likely to polymerization. If it happens, poor product quality, not just the appearance, but also in mechanical properties. Some exceptions, such as injecting a small amount, or some of the low viscosity of the material. Available light or heating stove heating, but an effective and commonly used method is used for making molded plastic dielectric heater.