GB838263A - Improvements in or relating to methods of continuously melting metal and electric arc vacuum furnaces for use therein - Google Patents

Abstract

838,263. Arc melting furnaces. HERAEUS G.m.b.H., W. C. June 9, 1958 [June 8, 1957], No. 18344/58. Class 39(3) [Also in Group XXII] In the continuous melting in an arc vacuum furnace of metals such as zirconium and titanium, rods 1 of the metal are fed into the furnace through an entry chamber 2 with a top cover 3 sealing the chamber against atmosphere and a lower cover 4 which may be swung out into an extension 5, and after evacuating the chamber 2 by a pump 6, the rod 1 is lowered by rollers 7 driven by a motor 8 into an adjacent part 9 of the furnace, to the position 10, where it is lowered by rollers 11 driven by a motor 12 against the electrode 13 to which it is welded by current fed to the metal 10, 13 by contact rollers 16, 17 by resistance or arc welding. The consumable electrode 13 is then melted by an arc 19 to form a first ingot 24 which is continuously lowered by rollers 28 and is melted by an arc 30 to form a second-ingot 32 of the required diameter, which is removed from the vacuum chamber without interrupting the continuous melting and while still maintaining the vacuum in the chamber. The ingots shrink slightly away from the watercooled jackets 22, 31 in which they are formed, and as the second ingot 32 is lowered by rollers 35 out of the furnace, the vacuum around it is maintained by a first vacuum jacket 33 connected to 'a vacuum pump 34 and the ingot 32 then passes through a second vacuum jacket 37 evacuated by a pump 38. Alternatively as in Fig. 2 the ingot 32 while still in the vacuum chamber is cut transversely at intervals at 50 by a circular saw 49 in an extension 48 of the chamber. The detached piece 58 of the ingot is moved by rollers 51 into a chamber 53 evacuated by a pump 54.. A cover 55 is then swung from a chamber 56 to seal the bottom of the evacuated furnace chamber, and after release of the vacuum in the chamber 53 containing the piece 58, a lower cover 57 is opened to remove the metal 58. Current is supplied by a generator 39 to the metal rod 10 at 16, to the electrode 13 at 20 through a choke 62 and to the first ingot 24, so that some of the current welding the rod 10 to the electrode 13 is fed to the arc 19. Insulating layers 15, 23 and 32 are placed between water-jacketted parts of the furnace 9, 14, 25 and 31 to which vacuum pumps 6, 21 and 27 are connected. The length of the first melting arc 19 is adjusted through a motor 18 driving the feeding rollers 20 of the electrode 13 through a control 41, and the length of the second melting arc is adjusted by a control 42 of a motor 36 driving feed rollers 35 of ingot 32. The first ingot 24 moves at constant speed.