摘要 |
<p>A coating liquid is squirted through a needle control nozzle directed into open end of internal threads of a fitting or tube and is deflected radially to form a spray cone by an air jet from a revolving nozzle set slightly in front and off the axis of the nozzle for the coating liquid. An end plate affixed to the revolving nozzle limits the forward spread of the spray cone, so that the coating thickness taper is cut off at the inner end of the coating on the threads. The thickness taper produced at the outer end of the threads by the spray cone favors easy engagement of the threads in making a tight threaded joint.</p> |