| 摘要 |
<p>Water tap having a conical plug turning with a hollow casing or barrel having a tapered bore has the plug and barrel components made of different plastic materials havng low interfacial friction and closely matched coefficients of thermal expansion over the temp. ranges and differentials anticipated in service, pref. the adequate dimensional thermal stability and stiffness at temps. up to at least 100 deg.C. Esp. suitable for domestic water tap designs, the plug is pref. moulded from polyvinylidene fluoride (PVDF), opt. contg. up to 10% PTFE (to reduce superficial friction) and the barrel is of PTFE, polyamide or polyolefin matl. esp. polypropylene. Alternatively the plug is of PVDF and the barrel of a PTFE+ PTFE blend, or vice versa. Axial thrust to maintain contact between the plug and barrel surfaces may be obtained using a coaxial bell collar of polypropylene (selected for a combination of elastic flexural fatigue resistance and heat resistance).</p> |
