In general, the vertical injection molding machine has […]
In general, the vertical injection molding machine has a back pressure adjustment regardless of the old fashion, and the adjustment valve is a pipe knob type.
Back pressure, also known as plasticizing pressure, is controlled by adjusting the oil return throttle valve of the injection cylinder. The back of the injection cylinder of the pre-plasticized screw injection molding machine is equipped with a back pressure valve to adjust the speed of the injection cylinder when the screw rotates backward, so that the cylinder maintains a certain pressure. The screw back speed (resistance) of the whole motor is AC servo. Valve controlled.
The benefits of proper adjustment of back pressure:
1. It can compact the melt in the barrel, increase the density, and improve the stability of the amount of glue, weight and size of the product.
2, can "extrude" the gas in the melt, reduce the air on the surface of the product, internal bubbles, improve gloss uniformity. Slow down the speed of the screw, so that the melt in the barrel is fully plasticized, increasing the mixing uniformity of the toner, the color master and the melt, and avoiding the color mixing phenomenon of the product.
3. Slow down the screw retreat speed, fully plasticize the melt in the barrel, increase the mixing uniformity of the toner, color masterbatch and melt material, and avoid the color mixing phenomenon of the product.
4, properly improve the back pressure, can improve the shrinkage of the surface of the product and the glue around the product.
5, can increase the temperature of the melt, improve the quality of the melt plasticization, improve the fluidity of the melt filling, the product surface has no cold rubber.