Under the dimension of the injection channel and s

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The size of mold injection channel and shunt channel (bottom)

it is particularly advantageous to adopt tunnel (latent) gate, because when it is opened by the mold. The plastic part and the runner system are automatically disconnected. The melt is injected into the cavity through a short tunnel at the end of the shunt channel. If the tunnel is properly designed, the gate is almost invisible Therefore, it is possible that there is no need to remove the secondary processing of the gate on the plastic parts. It has been found that this type of gate is not only suitable for PE (it is the first resin to use this kind of gate), but also plastic parts of PS, nylon (poly (acyl HA) (PA for short)) and other resins can be successfully formed by this method

however, it must be noted that some cases of doors are discussed below. There should be a large demoulding slope or step at the gate on the surface of the plastic part, otherwise scratches are easy to appear on the plastic part wall behind the gate

injection mold with 8 cavities of the molding sleeve

when injecting the molding sleeve, the common problem is that the core must not be deflected during injection, because this will lead to uneven wall thickness of the plastic part, and in order to shorten the cycle time, direct cooling method is applied to remove a large amount of heat on the core. The plastic part is a linear PE sleeve, which is used for Christmas tree lights (candle lights). The cavities are arranged circumferentially, so the length of the runner to each cavity is equal. The plastic part is fed through two tunnel gates at one end. The advantage of two gate feeding is that both sides of core 1 bear the injection pressure at the same time, so the core can be kept in the center. In addition, this feeding form ensures that the melt is evenly injected into the cavity, so it is conducive to exhaust. If the melt is injected by only one gate, the plastic part may carry air. Because there is a hole in the middle of the sleeve, it is easy to shape the center of the core by entering the centering part 2 with a small slope (about 5) when the mold is closed. A small flat surface is set around the centering part to eliminate the air in the cavity

the fixed mold insert 3 ensures the best cooling, because the cooling water is cooled through two interconnected channels close to the cavity and sealed with O-rings. The core "Green Plan" has been praised by all parties. A channel with a diameter of about 6mm is set in the channel, and a 4mm pipe 4 screwed with an elbow is set in the channel. The cooling water flows in through the pipe and flows out from the gap between the pipe and the channel wall. The runner system is only set at the fixed mold side of the mold. The runner system is left at the edge of the moving die by the pull rod 5. Once the mold is opened, the sleeve is pushed out of the core by the stripper 6. At the same time, the runner system is detached from the pull rod. When the mold is opened, because the tunnel gate is cut off from the plastic part, the plastic part and 1 generally clamp the two ends of the material sample on two fixtures with a certain distance between them. How can the horizontal tensile testing machine fall from the mold

because the plastic part has been disconnected from the runner during ejection, the runner system cannot be used when ejecting the plastic part. Therefore, for each plastic part, the design of the stripping device must ensure the demoulding of each plastic part

slotted gate

if a large and flat plastic part is directly fed by a point gate, serious warping deformation will be caused due to the different shrinkage of the plastic part along the flow direction and perpendicular to the flow direction, especially the resin (PE) with large shrinkage. If the rectangular plastic part is fed by a parallel flow channel along the entire width of the plastic part, if the sheet metal is inadvertently scraped, the warping deformation of the plastic part can be basically suppressed. Although there are still different shrinkage rates along the flow direction and perpendicular to the flow direction, the warping deformation of the rectangular plate is no longer caused, and the influence of this different shrinkage amount is only considered when giving the size of the shaped cavity

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