US2569150A - Casting method and apparatus - Google Patents

Description

Sept 25, 195l l J. B. BRENNAN 2,569,150

CASTING vMETHOD AND APPARATUS Filed May 7, 1948 INVENTOR. .msn/f E. BMA/NAN ATToe/vfys.

Patented Sept. 25, 1951 UNITED STATES PATENT OFFICE CASTING METHODIAND APPARATUS A Joseph B. Brennan, Bratenahl, Ohio Application May 7. 1948, Serial No. 25,756 2 claims. (ci. zz-siz) n. vide a continuous casting apparatus which includes means for maintaining a substantially constant head of molten metal in a crucible disposed within a pressure chamber for assuming uniformity in casting results.

Another object is to provide a novel die passage heating and cooling arrangement for retaining molten the metal beingcast throughout substantially the entire length of the die passage whereby to eliminate sticking of the metal therein and for solidifying the skin of the metal being cast only suiiiciently that the metal retains its form upon emergence from the die, such solidifying occurring only at the very end of the die passage or immediately upon emergence therefrom, in which latter case solidification and emergence occur substantially simultaneously.

A further object is to provide a novel die passage heating and cooling arrangement as aforesaid which is operative to retain the mating inner faces of metals to be laminated in a heated and somewhat plastic condition whereby a firm union is attained when they are pressed together but which yet simultaneously provides cooled or unheated outer surfaces so that the metals will retain their form while being thus pressed together and in the case of laminating components including a rolled or otherwise formed metal the tensile strength, hardness, and other properties thereof will be diminished only a minimum amount as compared with the diminution of such properties which would otherwise result if the entire cross section of such metal were so heated.

Other objects and advantages will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, said invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention. these being indicative. however. of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing- Fig. l is a central vertical cross section view of 5 one embodiment of the present invention for continuously producing elongated stock;

Fig. 2 is a cross section view of a modification in the die for producing a laminated product from two cast strips or rods; and

Fig. 3 is a cross section view of a further modifcation similar to Fig. 2 with the exception that one of the strips or rods is cast while the other has been previously rolled, extruded, or otherwise formed.

Referring now to the drawing and first more particularly to Fig. l thereof, the apparatus exemplarily illustrated includes a pressure chamber I supported as by standards 2, said chamber comprising a dished plate 3 formed with an axial flange 4 radially notched as at 5. Such notches 5 extend axially for a short distance and then turn generally helically relative to the vertical axis of said plate 3. Fitted over said plate 3 is a bell 6 provided with radially projecting lugs I which cooperate with the notches 5 in a well-known \relative to the other.

manner to enable assembly and disassembly of said bell and plate simply by a part turn of one A sealing gasket 8 is compressed between said plate and bell to form a o gas-tight chamber therein. For facilitating relative rotation of said plate and bell the former is provided with a gear segment 9 about a portion of its periphery and the latter with a pinion I0 rotatably supported at the end of an arm II. A r suitable handle I2 is connected to said pinion I0 to enable rotation of said pinion and consequent relative rotation of said bell and plate. Said bell E is further provided with a window I4 on one side thereof.

Within said pressure chamber I and supported on I-beams I5 is a relatively shallow crucible I6 for containing molten metal to be cast said crucible being suitably heated by any desired means such as the electric heating element Il, the

leads I8 and I9 of which extend through said plate 3 to the exterior of said chamber I. Obviously. other heating means such as a high frequency induction coil or the like may be employed.

Depending downwardly from said crucible is a 0 nipple 20 also provided with an electric heating element 2| therein. An elbow conduit 23 is connected to plate 3 and is in communication with said nipple 20 through a central opening in said plate, said conduit being heated by the electric 5,-', heating elements 2l and 24.

Connected to the outer end of conduit 23 is a die 25 which has a passage 23 therethrough of desired size and and cross section shape to which the molten metal from crucible I6 will conform in being forced therethrough.

In order to maintain the casting metal in a. molten condition throughout substantiallyV the entire length of die passage 26 there is provided a high frequency induction coil 21 around said die extending from one end to the other thereof. By maintaining the metal in a molten condition, as aforesaid, sticking thereof along the walls of die passage 26 is completely avoided to thus greatly facilitate the casting operation. For solidifying the outer skin of metal so that it will more readily retain its ldesired form upon issuing from the outer end of said die there is provided exteriorly of bell l and has connected thereto a link mechanism 4I, 42 and 43 driven as by an a coolant passage 28 in said die at the extreme outer end through which suitable coolant uid is adapted to be circulated. By restricting the zone of solidiiication of the metal to the very end of the die passage 26, the heretofore encountered sticking problem is overcome. In lieu of coolant passage 28 or in addition thereto there may be provided spray cooling means 22 immediately adjacent the outer end of said die passage 26 whereby solidication and emergence of the metal from the die passage will occur practically simultaneously. Any solidication of the metal at the very end of the die passage is only suiilcient so that the metal will retain its cast form but insuicient to present the serious problem of sticking. If desired, a pair of rolls 29 may be disposed adjacent the outer end of die 25 for drawing the metal from the die and to further reduce, size or work the same.

Connected to bell 6 is a valve controlled pressure line 30 which is operative to admit gas (preferably an inert gas) at a desired superatmospheric temperature into the pressure chamber I so that the molten metal in lcrucible I6 will be forced out therefrom through nipple 20, conduit 23, and die 25 under a pressure considerably greater than the head of metal in said crucible.

One means, as fully illustrated and described in my Patent 2,371,604, dated March 20, 1945, for periodically charging crucible I6 without reducing the pressure in pressure chamber I comprises a charging chamber 3l having its lower end connected ,to bell 6 and its upper end formed with a cup 32 for receiving molten metal. Associated with said charging chamber 3| are upper and lower valves 34 and 35 adapted to be alternately operated to fill the charging chamber 3| with molten metal and to empty the same. To make possible the emptying of the contents of said charging chamber 3| without releasing the pressure in pressure chamber I, a valve 35 in line 31 connected to the upper portion of the charging chamber may be opened to admit gas at a super-atmospheric pressure into said charging chamber. Thus the molten metal in said charging chamber 3l when valve 35 is opened will be dumped essentially by gravity when the gas pressures within the pressure and charging chambers I and 3|v are equal.

To assure a substantially constant head of metal in crucible I6 and thus enable attainment of uniformity in the strip or rod which issues from die 25 there is interposed between charging chamber 3l and crucible I6 a tiltable crucible 38 controlled as will hereinafter appear by a float 39 associated with crucible I6. Said crucible 33 is mounted on trunnlcns 4| one of which extends electric motor 44. Saidlink mechanism is arranged as shown so that during one completo revolution of link 43 in a clockwise direction, as viewed in Fig. 1, said crucible 3l will first be rocked in a clockwise direction and then in a counter-clockwise direction. The motor 44 is controlled by a switch 45 on crucible I5 lactuated in response to the raising and lowering of fioat 33, said iioat having a switch engaging arm 43 thereon pivotally connected to crucible I6.

When crucible I6 is filled to a desired level with molten metal and as the casting operation pmgresses with metal being forced out through die 25, the float 33 will drop until switch 45 is closed, to start motor 44, whereupon said motor will. through the aforesaid linkage 4I, 42, and 43 rock said crucible 33 so as to pour metal therefrom into crucible I5, such tilting and pouring continuing until the level of metal in crucible I3 is again raised suiiiciently to cause the float 39 to open said switch 45 and thus stop said motor. After crucible 38 has been emptied or rocked to its maximum tilted position, continued rotation of motor 44 will, through the associated linkage mechanism, rock the same in a counter-clockwise direction to the position illustrated in which position the valve 35 may be opened to allow the contents of the charging chamber 3| to be dumped into said crucible 33. Thus it is apparent that with a mechanism as just described the head of metal in crucible I6 can be maintained substantially constant within prescribed limits y so that no noticeable variation in casting results can be attributed to loss of head of metal. Although the valves 34, 35, and 36 are herein manually operated, it will be apparent to those skilled in the art that the valve operations may be rendered automatic and responsive to the position of crucible 3l.

Referring now to the modification illustrated in Fig. 2, there is shown therein cast strips or rods A and B issuing from separate die passages 41 and 48 in a die 49 and pressed together by a pair of rolls 50 to form a laminated product. Each strip or rod is retained in a molten condition throughout the length of passages 41 and 43 as by means of the high frequency induction coil 5I thereabout and the outer surface onLv of each strip or rod is solidified by the cooling eiected at the extreme outer end of said die by the circulation of coolant throughout the pwages 52 and 53 and/or by the cooling effected by the spray cooling means 22. In this way the mating surfaces of strips or rods A and B are yet in a red-hot and plastic condition so that pressure exerted by the rolls 53 will effect a irm union of said strips or rods. It is to be understood that the die passages 41 and 43 will be associated either with two apparatuses ofthe type shown in Fig. l or else a single apparatus (not shown) provided with two crucibles I5 and 33, 'and two charging chambers 3|.

In the modification illustrated in Fig. 3 previously rolled, extruded. or otherwise formed strip C is drawn by the rolls 54 through a passage 56 in a die 51 from a coil 53 whereas a cast strip D issues from a passage 53 in said die'. A high frequency induction coil 5l is employed for retaining the strip D in a molten condition upto the very outer end of passage 59 at which point only the outer surface thereof /is cooled and soldied by the ow of coolant through the coolant passage II and/or by the iiow o! coolant onto such outer surface from the cooling means 22. However, in this case it is not desired to heat the entire cross section of the strip C to a redhot or plastic condition because of the consequent loss in tensile strength, hardness, and other properties. Therefore in association with die passage 56 is a coolant passage 62 which extends throughout substantially the entire length of passage 56 and is so disposed as to maintain the outer surface of strip C in an unheated condition with only the inner surface being heated to a red-hot or plastic condition. Here again, as described in connection with Fig. 2, the rolls 54 will press the strips C and D together to form a laminated product in which the components are firmly united together. As an example of one laminated product which may be formed, the rolled strip C may be of steel and the cast strip D of bronze or like metal.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. The method of continuous casting comprising laterally confining a longitudinally moving stream of molten metal and a longitudinally moving strip of metal, heating to plastic condition only that face of said strip to which it is desired to bond said molten metal while the remaining portion of said strip is retained in a nonplastic solid state, joining said strip and stream along such plastic face while thus laterally confined, solidifying at least the surface of the stream which is opposite to the surface thereof joined to the plastic face of said strip as aforesaid, and thereafter continuing movement of the joined stream and strip.

2. In a casting apparatus, a die formed with two passages merging together as a singlepassage, molten metal being adapted to be forced through one of such passages and solid metal stock Abeing adapted to pass through the other of such passages, and temperature modifying means surrounding such passages for retaining molten the metal adapted to be forced through such one passage and for heating to plastic condition only that face of the solid metal stock adapted to pass through such other passage to which it is desired to bond the molten metal while the remaining portion of the solid metal stock is retained in nonplastic solid state whereby the molten metal is welded to the plastic surface of the solid metal stock as the metals pass through such single passage, said means including a coolant passage formed in said die and through which coolant is adapted to be circulated to solidify at least the surface of the moltenmetal component opposite to the surface welded to the plastic surface of the solid metal stock prior to emergence thereof and of the solid metal stock from such single passage, such coolant passage extending along the walls of the single passage and such other passage corresponding to the surface of such remaining portion of the solid metal stock whereby to retain such remaining portion of the solid metal stock in non-plastic solid state during its passage through such other passage and such single passage.

JOSEPH B. BRENNAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,943,351 Stocketh et al. Jan. 16, 1934 1,995,258 Stockfieth Mar. 19, 1935 2,091,588 Fiegel Aug. 31, 1937 2,092,284 McCarroll et al Sept. 7, 1937 2,225,373 Goss Dec. 17, 1940 2,240,313 Ness Apr. 29, 1941 2,242,350 Eldred May 20, 1941 2,290,083 Webster July 14, 1942 2,301,902 Merle Nov. 10, 1942 2,371,604 Brennan Mar. 20, i945 FOREIGN PATENTS Number Country mie 3,367 Great Britain of 1902

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