| 摘要 |
1,183,335. Brazing. BURNLEY ENG. PRODUCTS Ltd. 7 April, 1967 [19 April, 1966; 23 June, 1966; 30 July, 1966; 24 Dec., 1966], Nos. 17037/66, 28125/66, 34326/66 and 57860/66. Heading B3R. A tape for use in brazing includes a base of hard flexible non-porous plastics material which carries a coating of powdered brazing alloy fixed to the base by an air-hardening binding agent which is miscible and unreactive with the base and which completely vaporizes on heating. To produce the strip, a liquid mixture of 1 part cellulose acetate to 3 parts of acetone is brushed on the periphery of a rotatable ring, the periphery being constituted by a copper backing with a chromium, ceramic or glass base enamel face, the coating is allowed to dry and at least partially to harden and a finely dispersed brazing alloy is fed from a hopper above the ring on to the coating while a liquid mixture of 1 part acrylic resin to 4 parts trichlorethylene is simultaneously sprayed on to the coating to fix the alloy. The trichlorethylene vaporizes and the alloy and acetate coating are cut transversely of the ring and peeled off. A release agent in the form of a high temperature brazing flux may be sprayed on to the cellulose acetate coating and allowed to dry before the resin and alloy are applied. Just prior to brazing the cellulose acetate base can be peeled off the tape taking most of the flux but leaving the alloy and resin. The parts are placed in a jig and a portion of the tape is placed between them and brazing in a spot welding machine is effected. The parts are placed in a furnace to complete the brazing. The resin vaporizes. The alloy may be of approx. 82% gold and 18% nickel; in which case pure nickel powder may be secured to the free side of the acetate base by resin to provide in the joint an alloy of higher melting point, the composite tape being inserted between the parts to be brazed. Other brazing alloys are 85% silver, 15% manganese; 3À5% silicon, 1À9% boron, 94À6% nickel; 4À5% silicon, 2À9% boron, 92.6% nickel; 10% silicon, 20% chromium, 3% iron, 67% nickel; 80% gold, 19% copper, 1% iron; 62À5% gold, 37À5% copper; 37À5% gold, 62À5% copper; 30% gold, 70% copper and 75% gold, 25% nickel. Instead of cellulose acetate, vinyl plastics, styrol resins, resinamines, acrylate polymers may be used and instead of acrylic resin, vinyl plastics. The tape may be passed over a pinned roller to provide perforations after being removed from the ring. |
