| 摘要 |
An improved method and injection molding system are provided for making a hollow plastic article wherein plastic resin is injected into an article-defining cavity so that the cavity is loosely filled but not filled to capacity with the plastic resin and wherein the article is defined within the cavity. At this time, the plastic resin has an undulating surface. Then, pressurized gas is injected into the plastic resin in the loosely filled cavity to distribute the plastic resin in the cavity and convert the undulating surface into a surface defined by the cavity, thereby forming at least one gas hole within the distributed plastic. Preferably, the plastic resin occupies approximately 92 % to 99 % of the volume of the cavity immediately after injecting the plastic resin. Preferably, the plastic resin in the cavity is sensed by a sensor during plastic resin injection to generate a signal for use by a hydraulic control system of the injection molding system to stop linear movement of a screw ram of the injection molding system. The sensor may be an infrared sensor assembly including an optical fiber bundle which defines a portion of the cavity. Alternatively, the sensor may be a pressure sensor, which also may define a portion of the cavity. The sensor may also be either an ultrasonic sensor or an electromagnetic sensor. |
