| 摘要 |
<p><PICT:0959586/C1/1> A cylindrical glass envelope 1 is shaped by placing it, open end downwards, over an undivided vertical tapered core 3, core and envelope being heated throughout substantially their whole length to collapse the envelope on to the core as a result of the surface tension of the glass and the pressure of the flames. After cooling the envelope is reheated to assist removal from the core while air may be blown on to the projecting part of the core. The core may have a projecting shoulder 4 to limit the elongation of the glass. The method is applicable to an envelope for a thermionic vacuum tube having an exhaust tube 2.</p> |
