Cemented carbide die tools injection die tools principle The die tools has a feeding cavity, which is connected to the closed injection die tools cavity through an in-die tools pouring system. When working, it is necessary to first add solid die tools materials to the feeding cavity for heating to transform it into a viscous fluid state, and then use a special plunger to pressurize the plastic melt in the feeding cavity through a press to make the melt pass through the die tools The pouring system enters the closed die tools cavity and performs flow filling. When the melt fills the die tools cavity, after proper pressure and solidification, the die tools can be opened to take off the product. At present, injection die tools is mainly used for thermosetting plastic products.
Cemented carbide mould
Compared with the compression die tools of the cemented carbide die tools, the plastic has been plasticized before entering the cavity during the injection die tools, so the die tools cycle is short, the production efficiency is high, the dimensional accuracy of the plastic parts is high, the surface quality is good, and the flash Very thin; it can be die toolsed with small inserts, deeper side holes and more complex plastic parts; consumes more raw materials; injection die tools shrinkage is greater than compression die tools shrinkage, which will affect the accuracy of plastic parts, but for powder The plastic parts filled with shaped fillers have little effect; the structure of the cemented carbide die tools injection die tools is more complex than that of the compression die tools, the die tools pressure is higher, and the operation is more difficult during die tools. Injection die tools is used only when the production requirements cannot be met by compression die tools. Injection die tools is suitable for the die tools of thermoset plastic parts with complex shapes and many inserts.
The main process parameters of cemented carbide die tools injection die tools include die tools pressure, die tools temperature, and die tools cycle, which are all related to factors such as plastic varieties, die tools structures, and parts.
(1) The forming pressure refers to the pressure exerted by the press on the melt in the feeding chamber through the pressing column or plunger. Due to the pressure loss when the melt passes through the gating system, the die tools pressure during injection die tools is generally 2 to 3 times that of compression die tools. The die tools pressure of phenolic plastic powder and amino plastic powder is usually 50~80MP a, and higher pressures can reach 100~200MPa; fiber-filled plastics are 80~160MP a; low-pressure packaging plastics such as epoxy resin and silicone are 2~ 10MPa.
(2) The die tools temperature of the cemented carbide die tools includes the temperature of the material in the feeding chamber and the temperature of the die tools itself. In order to ensure that the material has good fluidity, the material temperature must be appropriately lower than the crosslinking temperature by 10-20°C. Since the plastic can obtain a part of the frictional heat from it when it passes through the pouring system, the temperature of the feeding chamber and the die tools can be lower. The die tools temperature of injection die tools is usually 15~30℃ lower than that of compression die tools, generally 130~190℃.
(3) The injection die tools cycle of the cemented carbide die tools includes feeding time, filling time, crosslinking curing time, dedie tools time and die tools cleaning time, etc. The filling time of injection die tools is usually 5-50s, and the curing time depends on the type of plastic, the size, shape, wall thickness, preheating conditions and die tools structure, etc., usually 30-180s. Injection die tools requires that the plastic has greater fluidity before reaching the hardening temperature, and after reaching the hardening temperature, it must have a faster hardening speed. Commonly used materials for injection die tools are: phenolic plastic, melamine, epoxy resin and other plastics.
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