| 摘要 |
<p>One end of the metal tube has a conical taper which fits into the untapered end of a similar tube, i.e. the first end forms a plug whereas the untapered end forms a socket; this untapered end is not filled with wires for a length which matches the length of the tapered end. The latter is pref. provided with a step in its taper, the final portion of the taper being 15-30 mm long. When a lance has burned down to a length of 20-50 cm, it can very easily be mounted on the tapered end of a new lance. This method is rapid and inexpensive as opposed to conventional lances using e.g. threaded end connections which must also be protected against damage.</p> |
