| 摘要 |
<p>Pressurised cellular plastic, esp. for encapsulating communication modules for railway back-circuit signalling, is produced by mixing the foam forming components and filling them in a quantity, which suffices for the volumn of the appliance, into the open casing. The rising foam is slowed down over the full area by applying between the edge of the casing and a pressure absorption plate a plate of felt which has at least on one side a perforated anti-stick foil. This creates an adequately compacted foam without cavities which has a surface-free from bubbles. When attached to railway track, such encapsulation provides protection against moisture and shock loads.</p> |
