| 摘要 |
PURPOSE:To lessen the abrasion loss of throttle and spool as well as reduce the loss of power by providing a bypass leading to a return path from the midway of the inlet path of a mixing head without passing liquid plastic material through a throttle. CONSTITUTION:When molding is not made, when advancing a spool 16, different plastic raw materials flow into each inlet path 13, enter through a bypass 20 mainly into the groove 17 of the spool 16, and further return a return path 14 to a raw material tank. In this way, the liquid plastic material circulates between a mixing head and the raw material tank when molting is not made, during which period, however, the liquid plastic raw material mostly passes through the bypass 20. Thus, the circulation of the liquid plastic raw material can be made under low pressures with lesser amounts of heat being produced and also of power used, and the throttle 18 is also less abraded. |
