| 摘要 |
578,705. Making screw propellers. ENGINEERING & RESEARCH CORPORATION. March 16, 1944, No. 4961. Convention date, Feb. 17, 1943. [Classes 83 (ii) and 83 (iv)] Brazing.-In brazing parts such as propellers, . the parts with interposed brazing material are brought into face to face contact and whilst one part is rigidly supported the other is subjected to pressure to urge it against the first part by means of fluid pressure within a closed hollow expansible or deformable body which may be the second part or may engage the second part over substantially the area to be brazed. The parts may consist of the reinforcing tube 2 and the fairings 4, 6, 8, 10 of a propeller blade which are to be brazed at their areas of contact. They are placed with interposed brazing material in the cavities in a jig formed of two members 18, 20 connected by bolts. The leading and trailing edges 12, 16 of the fairing members rest on elongated flexible metallic tubes 30 in cavities 28 in the member 20. To braze the fairings to the tube 2, a fluid under pressure such as air or inert gas or a liquid is introduced into the tube either by valving or by sealing the tube, introducing the gas &c. at low pressure and allowing the brazing heat to expand the gas &c. to tend to change the shape of the tube from elongated to circular section and thus apply the clamping pressure. The tubes 30 may be similarly expanded when brazing the edges of the fairings together. In another form, the pressure may be applied through flat tubes 26 of flexible sheet copper or steel inserted in cavities 24 in the members 18, 20. In the case of reinforcing tubes which have tapered walls thicker at the hub end than at the tip, the cavities 24 are deepest at the hub end so that the clamping is produced by the expansion of the tubes 26, the cavities tapering so that at the tip end they are only deep enough to receive the two walls of the tube 26, in which case the pressure is effected by expansion of the thin end of the tube 2. |
