| 摘要 |
<p>The invention provides a pair of bodies with operative faces that can be brought face-to-face. The operative face of one body is formed with a row of similar openings spaced uniformly apart. Each opening has circular symmetry about an axis, and the axes of the openings are at right angles to the row and are spaced uniformly apart. The operative face of the other body has a row of locating formations which may also comprise a row of openings similar to one another and similar to those in said one body. The openings and formations are together such as to define a passageway for receving and locating a helical wire of pitch equal to the spacing between the axes of the openings in the said one body. The helical wire can be advanced relative to the bodies by rotating about its own axis.</p> |
