| 摘要 |
A vale assembly for a RIM system includes a body which defines a passage, a support structure within the passage, a poppet, and a detachable member which retains the poppet to the support structure. The valve assembly threads into a vent within a mold to provide a communication path for expanded material within the mold cavity. In operation, when a flow through the passage is below a predetermined force the detachable member is retained upon the stem and the valve remains open to provide venting of the mold cavity. Once the mixture expands into a more solid material and expands into the vent and valve assembly, the material flow provides a greater force against the poppet. Eventually, when a predetermined material flow generates a force upon the poppet greater than the predetermined force, the detachable member is detached from the stem and the poppet is pulled from the support structure. The poppet is driven by the material flow into a tapered section of the passage and the passage is blocked to prevent further escape of the densified material from the mold cavity.
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