US2996772A

US2996772A - Vacuum casting apparatus

Info

Publication number: US2996772A
Application number: US8625A
Authority: US
Inventors: Alexander J Deacon
Original assignee: UNMITED STATES STEEL CORP
Current assignee: UNMITED STATES STEEL Corp
Priority date: 1960-02-15
Filing date: 1960-02-15
Publication date: 1961-08-22
Anticipated expiration: 1978-08-22

Description

Aug. 22, 1961 A. J. DEACON VACUUM CASTING APPARATUS Filed Feb. 15, 1960 I II I 1&5 39 L37??6 L30 20 2 Sheets-Sheet 2 IN VEN TOR.

AZ EXA/VDEQ J. 05460 ATTOR/VE/ United rates Patent 9 2,996,772 VACUUM CASTING APPARATUS Alexander J. Deacon, Chicago, Ill., assignor to United States Steel Corporation, a corporation of New Jersey Filed Feb. 15, 1960, Ser. No. 8,625 3 Claims. (Cl. 22-49) This invention relates to apparatus for teeming molten metal such as steel into molds under high vacuum, for the purpose of degassing the metal. More particularly my invention is an improvement on the apparatus of Hornak et al. Patent No. 2,885,751.

The prior patent states that warping caused by unequal expansion is a troublesome characteristic of vacuum casting chambers and that, while it can be prevented by insulation, the latter is objectionable because it absorbs gases. I have invented a vacuum casting chamber provided with a suspended shield or ceiling of insulation so constructed as to avoid the last-mentioned objection.

In a preferred embodiment of the invention, I provide a frame substantially the size of the top of the chamber and suspend it therefrom. I attach a plurality of metal trays to the frame and fill each tray with thermal insulation. A thin metal sheet is disposed over the panel and, together with the tray, forms a tight sheathing therefor, preventing absorption and release of gases by the insulation when the chamber is successively opened to the atmosphere and then evacuated preparatory to teeming. The several panels, when mounted on the frame, protect the top of the chamber from the heat radiated by the hot metal in the molds.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawmgs:

FIGURE 1 is a central vertical section through a vacuum casting chamber such as that of I-I'ornak et al. having my improved heat shield incorporated therein;

FIGURE 2 is a partial section taken along the plane of line II-II of FIGURE 1;

FIGURE 3 is a section showing a portion of FIGURE 2 to enlarged scale; and

FIGURE 4 is a partial section through the shield taken along the plane of line IV-IV of FIGURE 2.

Referring now in detail to the drawings, and for the present, particularly to FIGURE 1, 'a base has a platform 11 rotatable on a supporting framework 12 carried by a foundation 13. Platform 11 is adapted to receive a plurality of ingot molds 14 when the chamber (to be described next) is removed from the base. The evacuable chamber 15 enclosing the molds during teeming comprises a frame including posts and a ladle-supporting structure 17 from which a bell 19 is suspended by studs 18. The bell is open at the bottom and includes a cylindrical side wall 20 and a top 21. A pouring neck 22 is let into the top, with which the bottom nozzle of a teeming ladle 23 is adapted to aline when the ladle is placed on seat 24. The ladle bottom is sealed to top structure 17 at 25 and the bottom edge of hell 19 to base 10 at 26. The chamber as described so -far is substantially that of the Hornak et al. patent.

Coming now more particularly to the improvement of my invention, a heat shield or ceiling 27 is suspended ice within the bell 19 close to the top thereof. The suspended ceiling is composed of a frame or grid 28 made up of intersecting T-sections 29 and angles 30 connecting the ends of the Ts as shown, to form an octagonal circumferential rail. Studs 31 welded to the top 21 and extending downwardly therefrom support the frame at intersections of Ts 29. Angle straps 32 bolted to the frame are welded to the side wall 20 of bell 21.

Panels 33 and 34 are secured to frame 28 by suspending bolts 35. The five square panels 33 and four triangular panels 34 together constitute a ceiling extending over substantially the entire area of top 21. Each panel is formed from a tray 36 of steel plate tilled with thermal insulation slabs 37. A thin metal sheet 38 extends over the surface of the insulation. Trays 36 and sheets 38 together constitute tight closures for slabs 37. Stififening ribs 39 are welded to the bottoms of trays 36 to give them rigidity. As shown in FIGURE 2, one of the panels has a port 40 in the insulation thereof adapted to aline with neck 22.

It will be evident that shield 27 effectively protects top 21 from the extreme heat to which it would otherwise be subjected by radiation from hot metal in molds 14. The shield is supported largely on studs 31 and is centered by brackets 32. Flexing of the latter permits limited expansion and contraction of the bell 19 relative to frame 28. The panels may be removed individually from the frame for inspection or replacement. Trays 36 are preferably made of stainless steel so as to withstand the heat from the metal in molds 14. The tight enclosure of the slabs of insulation between the trays 36 and covering sheets 38 limits the absorption of gases by the insulation when bell 19 is removed from base 10.

In addition to the foregoing advantages, my heat shield is simple and inexpensive in construction so it does not materially increase the cost of the vacuum casting apparatus as a whole. It requires no maintenance and, once installed, is good for the life of the bell.

Although I have disclosed herein the preferred embodiment. of my invention, I intend to cover as well any change or modification therein which may be made without departing from the spirit and scope of the invention.

I claim:

1. The combination with a metal-teeming chamber including a side wall and a top, of a ceiling suspended therein adjacent said top comprising a frame including a circumferential rail and beams extending transversely thereof and secured thereto, and panels of thermal insulation substantially filling the spaces between said rail and beams, hanger studs secured to said beams and said top and centering brackets secured to said rail and bearing against said wall.

2. The combination defined in claim 1, characterized by said brackets extending generally tangentially of said wall.

3. The combination defined in claim 1, characterized by said beams being of T-section.

References Cited in the file of this patent UNITED STATES PATENTS 1,570,720 Baker J an. 26, 1926 2,269,645 Browning Jan. 13, 1942 2,559,763 Ginder et a1 July 10, 1951 2,885,751 Hornak et al. May 12, 1959