Injection molding意甲下注 process, cooling stage
inDalian injection moldingThe design of the mould, the cooling system is very important.This is because the only cooling solidification molding plastic products to a certain rigidity, stripping to avoid plastic deformation caused by external forces.Due to the cooling time of the molding cycle is about 70% ~ 70%, thus well designed cooling system can greatly shorten the molding time, improve the injection molding productivity, reduce the cost.Improper design of the cooling system can make the molding time stretched, increased cost;Uneven cooling will further cause plastic buckling deformation.
The cooling system design rules:
Design cooling system, mold designers must be decided by the thickness and volume of the plastic pieces of the following design parameters, the position of cooling holes and the kinds of length, hole size, hole, hole configuration and connection and rate of cooling fluid flow and heat transfer properties.
意甲下注The design of the cooling channels to ensure the uniform cooling effect and fast.
意甲下注Cooling systems are designed to maintain the mould proper and efficient cooling.Cooling holes should use standard size to facilitate processing and assembly.
The factors influencing product cooling rate are:
The cooling water pipe configuration mode.The cooling water pipe near the cavity, pipe diameter, the greater the number, the more the better cooling effect, the shorter the cooling time.
Coolant flow rate.Cooling water flow rate (usually in order to achieve the greater the turbulence is preferred), the effect of cooling water in thermal convection heat can be taken away.
意甲下注Plastic products design.Mainly plastic products wall thickness.The longer the product thickness, the greater the cooling time.About and plastic products in general, the cooling time is proportional to the square of the thickness, or with the direct ratio of 1.6 times the diameter of the largest port.The thickness of the plastic double, cooldown increased four times.
意甲下注Plastic option.Plastic is refers to the plastic will be the direction of heat from the hot to cold place conduction velocity measurement.Plastic heat conduction coefficient is higher, on behalf of the heat transfer effect is better, or plastic heat low, temperature change easily, so easy to heat dissipation, the heat transfer effect is better, the required cooling time is shorter.
意甲下注Processing parameters.The higher the higher the feed temperature, die temperature, ejection temperature is lower, the longer the cooling time required.
意甲下注The nature of the cooling fluid.Cooling fluid viscosity and thermal conductivity coefficient can also affect the heat conduction effect of mold.Cooling fluid viscosity is lower, the higher the heat transfer coefficient, the lower the temperature, the cooling effect is better.
Mould material and cooling way.Advanced materials, including mold core, mold material and the die set has much effect on the cooling rate.Mold material heat transfer coefficient is higher, the unit time transfer heat from the plastic and the effect is better, cooling time is shorter.
, according to the experiment by heat melt into the mold send out roughly divided into two parts, part of 5% of the radiation and convection to the atmosphere, the remaining 95% conduct from the melt to the mold.Plastic products in the mould due to the effect of the cooling water pipe, plastic through heat conduction of heat by the cavity by the die set to cooling water pipe, through the thermal convection was taken away by the cooling fluid.A few not taken away by cooling water continued to heat conduction in the mould, overflow in the air after the contact with the outside world.
Injection moldingBy clamping molding cycle time, the fill time, the holding time, cooling time and stripping time.With cooling time proportion is the largest, is about 70% ~ 80%.So the cooling time will directly affect molding cycle length and the size of the production of plastic products.Stripping stage plastic temperature should be cool to below the heat distortion temperature of the plastic products, in order to prevent the plastic products caused by residual stress relaxation phenomenon or release the warping and deformation caused by the force.