| 摘要 |
812,713. Cutting by fusion. ZEISS-STIFTUNG, C. [trading as ZEISS, C. [Firm of]]. June 25, 1956 [July 6, 1955], No. 19549/56. Drawings to Specification. Class 83 (4). [Also in Group XL (a)] A piece of material is "worked," e.g. by boring holes in it, by means of a beam of charged particles of which the intensity varies so as to have alternate maxima and minima in time, the "working" taking place only during the maxima so as to enable the material to cool between times of maximum intensity, so restricting the molten parts of the material to the area to be worked, the neighbouring areas remaining relatively cool. The beam of particles is preferably pulsed, the intensity between pulses being zero or a small finite value, and the pulses may be formed by (a) mechanical means such as a rotating shutter; (b) electrical means, e.g. by varying the emission of the source; (c) deflecting the beam by electrostatic deflecting plates; (d) defocusing the beam by a lens. The beam intensity may be varied during each pulse. The defocusing or deflection between pulses can be so selected as to temper the material. The beam density is constant over its cross-section and the time intervals between successive pulses are constant. The volatilized material may be made to react chemically with a gas introduced. The shorter the pulses the sharper the temperature gradient at the edge of the worked area, and the intensity and duration of the pulses are selected to obtain the desired temperature distribution over the surface to be "worked". For boring conical holes, the focusing means are adjusted to vary the cross-sectional area of the beam from pulse to pulse. For working a large zone or for working a zone at various places relative motion is set up between beam and material during irradiation or between pulses. To irradiate several objects they are successively exposed to consecutive pulses, by feeding the objects along or by deflecting the beam. There may be several pulsed beams of charged particles of different composition which impinge on the object one after the other; part of each of the beams can impinge simultaneously on the same zone. To reduce thermal stresses the object can be heated by other beams of charged particles or by electrical heating devices before, during and after working. The heating is in this case'regulated by photo-electric or thermoelectric devices. The latter devices can also automatically "regulate" the beam in dependence on the heat generated in working. For chemical effects or to obtain surface coatings on partial zones or on the entire zone, additional substances can be sputtered on between pulses or at other times. |
