| 摘要 |
<p>The invention provides a blowing agent metering system (10) and method for use in polymeric foam processing. The system may be used to control the rate of introduction of blowing agent into polymeric material in a processing apparatus. The metering system includes a restriction orifice (34) which is positioned in a pathway between a blowing agent source (21) and a blowing agent port (22). The metering system measures the pressure differential as blowing agent flows across the restriction orifice from the source to the port and may also measure the temperature of the blowing agent. Using a pre-determined relationship between the flow rate, the orifice dimensions (e.g., length, diameter) and the measured variables (e.g., pressure differential, temperature), a controller (44) of the system adjusts pressure upstream of the restriction orifice in response to inputs of the measured variable to maintain a pressure differential across the orifice that provides the desired blowing agent flow rate.</p> |
