| Abstract: | This utility model relates to a plastic injection molding machine. In the hydraulic system of this machine, a pipeline is installed from the front of cooler to the oil outlet of plunger variable pump, and a check valve which the flow direction is from the oil outlet to the cooler is mounted on it. Otherwise, a check valve which the flow direction is from the oil outlet to the oil box is mounted between the oil outlet of plunger variable pump and the oil box, and its open pressure is bigger than the previous one. When the injection molding machine is working, all returning oil would be cooled by the cooler, and then entered into the oil box. When the machine is waiting for operation or has few returning oil, all overflowed hydraulic oil would be passed through the cooler firstly and then entered into the oil box, so the again rising of temperature for hydraulic oil has been prevented. Thereby, the working life of sealing element in the oil pump and the sealing element on the whole machine will be prolonged, at the same time, the oil seepage caused by the reducing of viscosity of the hydraulic oil due to the temperature of oil rising is also eliminated, the sealing performance of the injection molding machine has been enhanced. |
