US2636219A - Method of producing shot - Google Patents

Description

April 1953 P. w. BEAMER ETAL 2,636,219

' METHOD OF PRODUCING SHOT Filed Aug. 25, 1950 2 Sl-lEETS-SHEET 1 WITNESSES: INVENTORS Paul W. Beomer and fl Wilson Yoglinggr. F Ao'Rm-nr fi Apnl 28, 1953 P. w. BEAMER ET AL 2,636,219

METHOD OF PRODUCING SHOT Filed Aug. 25. 1950 2 SHEETS-SHEET 2 7 2% o o a .24? o (122/0 o o o 1a 0 o o a% z 0 o o o o o o o 0% )AA 7 ,WITNESSES: INVENTORS Patented Apr. 28, 1953 METHOD OF PRODUCING SHOT Paul W. Beamer, Irwin, and Wilson G. Young, Jr.,

Pittsburgh, Pa.,

assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 23, 1950, Serial No. 180,974

This invention relates to a method of producing melting stock and particularly to a method of producing melting stock in the form of metallic shot for use in precision casting.

Heretofore, melting stock for us in precision casting was produced by either pouring molten metal into core sand molds, thus forming cast pins, or by breaking up a stream of molten metal with a single jet of water so as to produce metallic shot. This latter method was carried out by first pouring molten metal contaminated with slag into an inclined V-shaped ceramic-lined trough. In order to remove the slag from the molten metal, a partition or dam was provided midway the length of the trough. The partition had an opening in the bottom thereof to allow the flow of the molten metal therethrough, the slag being retained in the trough by the dam. After passing through the opening in the partition, the molten metal continued to run down the inclined trough until it spilled over the end in the form of a stream of molten metal. This stream was then broken up by means of a single jet of water, thus producing the metallic shot.

These former methods of producing metallic shot, however, had several disadvantages. In the case of the cast pins formed by pouring the molten metal into the sand molds, the cost and time consumed in producing each pin were considerable. The other method in which metallic shot was produced had its disadvantages too. Th size of the metallic shot produced by this latter method varied over wide limits, which was undesirable. The size of the shot produced ranged from extremely fine particles which would pass through a 20 mesh screen to very coarse particles which would not pass through a 2 mesh screen. I

Where shot is used as the melting stock for the making of precision castings, the size of the shot is critical and must be closely controlled for best results. If it is too fine, its surface area is large with respect to the amount of metal of the shot which means that the amount of oxide on its surface for the given amount of metal is great. This is undesirable because the greater the amount of oxide per unit weight of metallic shot the greater is the amount of slag formed when the metal is remelted. The slag formed must be removed from the remelted material prior to its use in precision casting. If the metallic shot is too coarse, another problem arises since it will not pass through the mouth of a remelting furnace of the type used in melting stock for the making of precision castings. Therefore, un-

3 Claims. (Cl...18,47.3)

less the size of the metallic shot is proper, a great deal of the shot produced will have to be discarded.

Another disadvantage of the last-mentioned method in which metallic shot is produced is that the slag contaminates the ceramic-lined trough through which the metal runs with the result that the trough must be frequently replaced, causing time delays in the production of the shot as well as greatly adding to the cost thereof. The apparatus for carrying out the teachings of this invention is so constructed as to avoid this problem. a

An object of this invention is the provision of a method for making metallic shot that is substantially spherical in shape and has a minimum of oxide on its surface. Another object of this invention is to provide for subjecting a stream of molten metal to the action of a plurality of jets of water to impart a rotary motion to the metal and effectively break the stream into a plurality of substantially spherical shot.

Other ob ects of this invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which: I

Figure l is an elevation view of the apparatus constructed in accordance with this invention;

Figure 2 is a detailed plan view of the shot ring shown in Figure 1; and

. Figure 3 is a view in section taken along the line III-III of Figure 2 of the shot ring constructed in accordance with this invention.

Referring to Fig. 1 of the drawing, there is illustrated metallic shot-producing apparatus 8 for carrying out the teachings of this invention. As illustrated, the shot-producing apparatus 8 comprises a shot-making ring Ill disposed to receive molten metal II from a pouring receptacle l2 which is supplied from a melting furnace or reservoir l4 containing the molten metal H, a tank [6 being positioned below the shot ring [8 for receiving the shot a will bedescribed more fully hereinafter.

As illustrated, the pouring receptacle I2 is preferably a clay-graphite'tundish having an opening I 8 through the bottom for guiding the stream of molten metal ll into the shot ring Hi. The

receptacle I2 is utilized to provide a constantsupply of metal to the ring Ill, such supply being controlled by maintaining the level of the molten metal H in the tundish at a predetermined height to maintain a predetermined pressure member with the edges of the ch nnel weld d V or brazed to the outer surfaeefof the h ollbw cyl n: drical member 20 to fornfa- 'tili se'd conduit for the Water that is being supplied tdth passage-1 ways 22. Water 26 may be supplied to the chamber 24 from any suitable scarce of supply (not shown) through a supply pipe 28 in the wall of the chamber 24. The water is preferably under a predetermined regulated pressure to control the size and shape" crime sheets be produced, as will be" explained more fully hereinafter."

For the purpose of cooling and solidifying the metallic shot," tank lFpartia'll-y fines with water is provided. The tam; i6 is" disposed d i rectly beneath 'the shotfrifig lll so as to r ceive the metallic sho'tiwhen' in 'its plastic st t In ordezth'atthe waterlevel the tank is may remain' 'coristaritfan' o emow preset is provided. In practiee; the "water lever iri the tank is must be maintainedat a'cons'tant value, otherwise the size of -theii ita'lli shot producewwiu '2 Referring to Figs. 2 and 3; the passageways 22 ar eillu'strate d as" be ngrbrm ein' tiers 'witli' the passageways 22 remain ass rt tier'spaced close enough together to site predetermined distribution of water in the cefiterspece o'fthe shot ringu'q. In the embodiment illustrated, the passageways" 22 are prerer'atiy'spaeea 20 1 degrees a ai wahrespec't we passagewa zm the same tier.' 'In'ordertofprevent too'high aeoncentra tion of water at anyone" pointaii'dthereby cause a g-eysering effect upwardly from such a point, the:passag e'wa'ys a e-are distributed infspaced tiers as illustrated 'in' Fig. '3," thefpassageways 22 of eachof thetfers being staggered 'with respect to the passageways 22 of the adjacent tiers? In a specifiembodinientillustrated; three tiers of'the staggered passageways 'z z ha ye been found to be satisfactory. 'In' this embodiment, tlie tjhree-tiers of passageways 22 will provide a pa ssageway- 2-2 et ery'o 'degrees and 40 minutes about the ch1 cumference of the" hollow cylindrical wall rnember2fl." M

'As illustrated, each of thewpassageways 22in each.- tier, is. inclined downwardly; and inwardly Withrespect to the memberlfli The-angled ink at on or eupassasew ys. s crit al; e n v preferably between 20,? and: 69.; with. ,espect to the vertical as. it is found that, 'ff lar er than 609 then the. jets oi wa rum ge on one another in a, manner tqimm a',.yerti cal column of water .w ienma strikel the bot to r n o the tumziishf 2, wher as' ll he. a is le than 20, the jets or water are ine ak prthestream-q molten me a mm. t uinformly siaedshot' es l fi that h t? hfl SP,

No geysering of the water is obtained where the water jets strike the stream of molten metal in this manner.

While the jets of water are effective in breaking up the stream of molten metal into small particles i o d to impart. a substantially spherical shape to the particles, the passageways 22 of each of the tiers are so drilled and positioned in the hollow cylindrical member 20 that the jets of water emerging from each tier impinge tangentially on the circumference of a inch diameter imaginary circle centrally loe ated with respect. to the shot ring H]. By so ing thepassageways 22, the jets of water ,ns thereirom effect a swirling or rotary motion of the water centrally located with respool}. to the shot, ring I. Each of the centrally located imaginary circles is not located in the plane formed by its associated tier of passageways '22 but rather is spaced a predetermined distance thereifirorn. It can be seen that with three spaced tiers 0E staggered water jets there will be three imaginary circles, the circumfer ences of which have jets of water impingingon them. As the molten metal strikes the jets of water, the jets break up the stream of metal and impart a rotary motion to the particles of molten metal to form substantially spherical shot. The rotary motion that is given the particles of molten metalis effected by having the jets of water formedbythe-passageways 22 impinge tangentially onthe circumferences of their respective imaginary circles whereby the metal particles strucl r by one of the jets are carried toward the area ofthe imaginarycirole, and as the metal particle passes from one impinging jet to the other, a rotary-motion-is imparted=to the particleto impart a substantially"sphericar shape thereto.

In practice, it has-been found desirabletoprovide a shot r-ing 10': whose cylindrical member 2-9 has an outside'd-iameter of'5% inches, a height of Sinches, a wallthiclmess-of of'an inch,- anda distance of 2 inch between eacho'f' the tiersof passageways 22-; the diameter-of each of the passageways 2 2- being oi an inch with the passage ways 2-2 disposed in the member 20* as v described herei nbefore; A conical'-shaped tundish E 2 having; an inside diameterot le'inches -atthe-top, a 3 inch inside diameterat the-bottom, a heigl'it of 1-2 inches, a wall thickness-of 1- inch at the-top and 1 inches-at thebottom, anda diameter of 6; of; aninch for the aperture l S -issatisfactory.

In practice, when using apparatus-having-the above dimensions, it is-desirable to maintain the heightpf the metal -in the-tundisls t2f2at 2 inches to give a sufiicient pressure-heacltothe: stream of metal flowing to the ring it. With such'a pressurehead; the-distance between-the tundish i t a ndthe hollow shot ring-l fi is maintained' at '5 inches, and thedistance-between thehollow shot ring iB- an-d-the level of the water in th e tank-d B at f8-inches;- In orderto obtainproper-results the water-pressure should be maintained at 15 pounds: per-"square inchg and the: pouring temperatu-rebf the'molten metal-between IEGG C. and l525 C:

In operation, the --molten metal-is poured from the reservoir- Hi 'into;-the--clay-graphite --tundish 2 to a height -necessary'to produce the desi-red pressure head: The tundish -lZ'is'prefer-ablypreheated with ages burner; (not showni-"prior to dmit i ghe malice-me a -;ithereto--to @rrevent chilling ofthgmetal; The-molten metal ii-o'ws through -theapertureor-orifice-i-fl 'of the tdndish [2 in a steady stream, as long as the pressure head is maintained, into the center space of the. shot ring i0.- When the stream of metal reaches the jets of water that emerge from the inclined and staggered passageways 22, the stream of molten metal is broken into particles and a roitary motion" imparted thereto which forms the particles of plastic metal into substantially spherical shaped shot. The metallic shot thus produced is in a plastic state until it strikes the water in the tank i6. However, once the shot strikes the water and starts to fall to the bottom of the tank IE, it is so cooled that it solidifies to retain the substantially spherical shape imparted thereto. The shot may be removed from the tank [6 in a. conventional manner.

The method embodying the teaching of this invention has many advantages. Among these are that the shot produced is more uniform in size and spherical in shape than that produced by prior known methods. This uniformity in size and spherical shape permits a more efficient removal of surface oxides during washing and blending.

From the operational point of view, the apparatusfor carrying out the method of this invention possesses several advantages. The pouring time is appreciably decreased which permits maintaining a more nearly constant melt temperature and also aids in obtaining a more uniform size and shape of shot. Preheating of the tundish I2 is simplified since the tundish is movable and can be heated with a gas burner away from the reservoir 14 and the heated tundish 12 can then be positioned to receive the metal when the metal is ready to pour. In addition, the tundish [2, since it is not contaminated with slag, as was the formerly used V-shaped ceramiclined trough, does not require any maintenance.

A still further advantage is that pouring is simplified considerably since no special precautions are required in order to maintain a corn stant stream of molten metal. This is automatically taken care of by keeping a predetermined head of molten metal in the tundish I2,

We claim as our invention:

1. In the method of making metallic shot, the steps comprising, providing a plurality of tiers of jets of water, each tier of water jets having imaginary centrally located circle associated therewith, directing the jets of water of each tier so as to impinge tangentially on the circumference of their espective imaginary centrally located circle,

tating in one predetermined direction, and directing a stream of molten meta1 into the jets Tor water whereby the jets of water break the metal up into particles and carry the particles towards bining the plurality of tiers jof jets of water to simulate a cylinder of water 11.

the cylinder of rotating water, the jets imparting a rotary motion to the particles to produce substantially spherical shot therefrom as the particles pass from one to another of the impinging jets forming the cylinder of water.

2. In the method of making metallic shot, the steps comprising, providing a plurality of tiers of jets of water, each tier of water jets having an imaginary centrally located circle associated therewith, inclining the jets of water of each tier downwardly at an angle between 20 and to the vertical, directing the jets of water of each tier so as to impinge tangentially on the circumference of their respective imaginary centrally located circle, combining the plurality of tiers of jets of water to simulate a cylinder of water rotating in one predetermined direction, and directing a stream of molten meta1 into the jets of water whereby the jets of water break the metal up into particles and carry the particles towards the cylinder of rotating water, the jets imparting a rotary motion to the particles to produce substantially spherical shot therefrom as the particles pass from one to another of the impinging jets forming the cylinder of water.

3. In the method of making metallic shot, the steps comprising, providing a plurality of tiers of jets of water, spacing the jets of water of any one tier not'more than 20 apart, each tier of water jets having an imaginary centrally located circle associated therewith, inclining the jets of water of each tier downwardly at an angle between 20 and 60 to the vertical, directing the jets of water of each tier so as to impinge tangentially on the circumference of their respective imaginary centrally located circle, combining the plurality of tiers oi jets of water in vertically spaced relationship and staggering the jets of water of each tier with respect to the jets of water in the adjacent tier to simulate a cylinder of water rotating in one predetermined direction, and directing a stream of molten metal into the jets of water whereby the jets of water break the metal up into particles and carry the particles towards the cylinder of rotating water, the jets imparting a rotary motion to the particles to produce substantially spherical shot therefrom as the particles pass from one to another of the impinging jets forming the cylinder of water.

PAUL W. BEAMER. WILSON G. YOUNG, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,627,982 Magnet May 10, 1927 2,402,441 Paddle June 18, 1946 2,417,301 Hayes Mar. 11, 1947

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