US3177052A - Billet log - Google Patents

Description

April 6, 1965 J. HUNTER ETAL BILLET LOG 5 Sheets-Sheet 1 Filed Nov. 10. 1961 BILLET LOG 5 Sheets-Sheet 2 J. L. HUNTER ETAL April 6, 1965 Filed Nov. I0. 1961 E mTm E U M V E mL %E L m JA B? i 3 i THU! QM 1|| 3 iv m .llsl

April 6, 1965 Filed Nov. 10. 1961 J. L. HUNTER ETAL BILLET LOG 5 Sheets-Sheet 3 IFIlG*3 April 1965 J. HUNTER ETAL 3,177,052

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JGSEPH L. HUNTER y AXEL E. JENSEN April 1965 J. L. HUNTER ETAL 3,177,052

BILLET LOG Filed Nov. 10. 1961 5 Sheets-Sheet 5 54.6 C a SOL INVENTORS. JOSEPH L.HUNTER AXEL E. JENSEN United States Patent York Filed Nov. 19, 1961, Ser. No. 152,377 1 Claim. (Cl. 29-187) The present invention relates to metal casting and in particular to a method and to an apparatus for casting billets. The invention also relates to a novel billet structure.

This application is a continuation-impart of copending application S.N. 822,238, filed June 23, 1959, entitled Billet Casting Method and Apparatus.

A particular feature of the invention is the provision of a novel casting apparatus.

A further feature of the invention is the provision of a novel method of casting individual billets in sequential fashion.

A further feature of the invention is the provision of a log of billets.

A further feature of the invention is the provision of a method and apparatus for the production of individual billets where the billets produced are connected in series to form a line of billets.

A further feature of the invention is the provision of a method of casting billets sequentially in which a billet while being cast acts as a riser or hot top for the next preceding billet.

A further feature of the invention is the provision of a mold cavity having a self-regulating feed system.

A still further feature of the invention is the provision of a movable mold cavity which cooperates with a liquid metal feed tube to regulate the flow of metal into the mold.

A still further feature of the invention is the provision of a billet casting process which can be practiced to produce billets of a given length in sequential fashion.

A further feature of the invention is the process step which embraces utilizing a must billet to haul the next succeeding billet out of the billet mold.

A still further feature of the invention is the provision of a billet casting apparatus which produced a connected line of individual billets where the line of billets move with the billet mold during the casting operation.

A further feature of the invention is the provision of a billet casting process utilizing a reciprocating mold where the length of billet cast is measured by the stroke of the mold.

A billet casting process embracing certain features of the present invention may include the steps of providing a movable hollow mold, blocking one end of the mold, providing a source of molten metal, providing a feed tube communicating with the source of metal and with the interior of the mold, introducing molten metal into the interior of the mold through said tube, moving the mold and the tube relative to one another through a definite stroke as metal is supplied so that the metal flows into and fills the interior of the mold, the length of said stroke determining the length of the billet cast.

A billet casting apparatus embracing certain features of the invention and operative to practice the process steps thereof may comprise a main frame; an open ended, movable, hollow mold mounted upon the frame; means for closing one end of the mold; a molten metal feed pipe communicating with the interior of the mold through an open .end thereof and connected to a source of molten metal; means for moving the mold and the feed pipe relative to one another from a starting position through 'ice a definite stroke as metal is fed to the mold so as to cast a billet; means for locking the closing means and the mold together to preclude relative motion therebetween during the casting stroke; means for moving the mold and the feed pipe relative to one another through a. return stroke so as to return said mold and feed pipe to said starting position, and means for holding the billet relative to the frame and for releasing the mold during said return stroke.

A plurality of connected billets cast by utilizing the method and apparatus of the present invention may comprise at least one cast billet of a given diameter connected to a second cast billet of corresponding diameter where the first and second billets are cast successively and are joined by a central neck, said billets being identified and partially separated by an annular cold shut which encircles said neck whereby a weakened cross-section is developed from billet to billet rendering said first and second billets readily separable.

Other features and advantages of the invention will become more apparent from the succeeding specification when read in conjunction with the appended drawings, in which:

FIG. 1 is a perspective view of an apparatus embracing the principles of the present invention and operative to practice the process steps thereof;

FIG. 2 is a section of the illustration of FIG. 1 as viewed in the plane of line 2-2;

FIG. 3 is a vertical section of FIG. 1 as viewed in the plane of line 33 and in the direction of the arrows;

FIG. 4 is a schematic of the hydraulic system;

FIG. 5 is a schematic of the electrical system; and,

FIG. 6 is a perspective view of a portion of a line of billets showing the effect of a cold shut.

Referring now to the drawings and in particular to FIGS. 1,2 and 3, there is shown a main frame 19 supporting a pair of uprights 11 and 12 tied together at the top of the uprights by a T-shaped channel member 13.

The uprights support a pair of horizontally disposed guide rods 14 and 16 in turn operative to carry a mold 17 by means of suitable bearings 18-18 and 19l.

The mold 17 is movable in reciprocatory fashion along the guide rods (by means which will become more apparent hereinafter) from a starting position corresponding to the solid line position of the mold shown in FIG. 2 through a uniform casting stroke to a position indicated by the dotted lines in FIG. 2 and designated by the letter A.

The mold 317, hollow and open ended, is cored as at 21 to provide a passageway or annular cavity about the mold into which an appropriate heat transfer fluid is circulated. The fluid is supplied and discharged from the mold by means of the conduits 22 and 23, respectively.

Rigidly mounted to the upright 12 and communicab ing with a metering box 24 is a feed tube or feed pipe 26 having a head 27 whose periphery makes a sliding lit with the interior of the mold. The fit between the head 27 and the interior of the mold, although a sliding fit, is sufficiently snug to preclude more than just a flash of molten metal from flowing between the periphery of the head 27 and the internal surface of the mold.

The metering bOX 24 communicates with a source of molten metal (not shown) through a trough 28. A double acting air cylinder 29, supported on the right end (FIG. 1) by the upright 12 and on the left by a flange 31 formed integral with the mold 17, is operative to drive the mold from the starting position through a predetermined stroke to the dotted line position whereupon an axially adjustable block 15 carried by a rod 2t) contacts and actuates limit switch 33 to signal the end of the casting stroke and the beginning of the re- 7 turn stroke. An adjustable positive stop 25 adapted to contact the flange 31 cooperates with the limit switch 33 to insure a definite termination of the stroke at a precise length.

Correspondingly, when the mold 17 completes its return stroke, limit switch 34 is actuated by adjustable block 30 whereupon the air cylinder 29 is operated to drive the mold through a casting stroke.

Obviously, the blocks 15 and 30 and the positive stop 25 may be adjusted as desired to vary the length of the casting stroke. 7

In starting the casting process and in order to provide means for closing the left end of the mold (FIG. 1) a starting bar of the same general configuration of the cast billets BB shown in FIG. 2 is inserted into the left end of the mold into abutment with the face 36 of the'head of the feedpipe.

The purpose of the starting bar is to provide a surface against which molten metal may be cast; otherwise, metal introduced through the feed pipe 26 would flow from the pipe into the mold and thence directly out of the mold dropping upon the frame 10.

After the casting process is started, casting proceeds sequentially and, as will be more apparent hereinafter, each billet while being cast acts as a riser or hot top for the preceding billet.

or cast billets B-B, as the case may be, to the mold 17 to preclude relative motion between the billets (or the bar) and the mold during the casting'stroke.

As is most apparent in FIG. 3, the face of the flange 31 carries a pair of pivotally mounted arms 37 and 38 formed with inwardly projecting dogs 39 and 41, respectively.

A double acting air cylinder 42 is operative to drive the dogs into engagement with the billet B during the casting stroke thus clutching the billet to the mold securely. correspondingly, the cylinder is operative upon an appropriate signal to release the dogs during the return stroketo permit the mold to move relative to the billet line.

To hold the billet line BB immovable relative to the frame during the mold return stroke, a pair of opposed air cylinders 43 and 44 (FIG. 2) having finger members 46 and 47, respectively, are rigidly mounted upon the upright 11. The cylinders are operative upon appropriate signal to drive the fingers 46 and 47 into contact with the billet line to lock the billets to the frame 10 during the mold return stroke. 7

Obviously, the fingers 46 and 47 are withdrawn to a position free of the billet line during the casting or molding stroke.

At the left end of the machine, as viewed in FIG. 1,

three pairs of guide wheels 48.-48 are disposed in circumferential array and at 120 intervals about the periphery of the billet line to provide support and to maintain the longitudinal axis of the billet line coaxial with the longitudinal axis of the mold as the billets emerge from the casting apparatus. The guide wheels 4848 are pivotally mounted and each pair thereof is adjustable radially in order to facilitate alignment of the billet with the mold cavity. Referring now to FIGS. 4 and 5, it is apparent that a 110 volt potential is applied across the leads 51 and 52 so that upon closing switch 53, actuation of limit switch 34 is effective to energize time delays 54 and 56 having contacts 54a, 54b and 560, respectively. After a delay of one second, contacts 56a, normally closed, .open to deenergize solenoid D. Thereafter a spring 57, acting in opposition to solenoid D, is effective to open valve 58 to admit air pressure cylinder 42. Thus, the cylinder is effective to clamp the billet line BB to the mold 17.

After a two second delay, contacts 54b, normally Thus, the starting bar is utilized only in starting up the casting process.

Clutch means are provided for locking the starting bar closed, open to deenergize solenoid C and contacts 54a, normally open, close to energize lead 60. Spring 59, acting in opposition to solenoid C, is operative to open valve 61 admitting air pressure to the cylinder 29 to start the mold 17 along a casting stroke.

When the desired length of stroke is completed, the block 15 actuates limit switch 33 to energize time delays 62 and 63 having contacts 62a and 63a, respectively. Upon one second delay, contacts 63a, normally closed, are opened to deenergize time delay 56. Thus, contacts 56a are closed energizing solenoid D effective to shift valve 58 to admit air pressure to the cylinders 43 and 44 thereby causing the fingers 44 and 46 to clutch the line of billets to the frame 10.

After a desired dwell period incorporated in time delay 62, its contacts 62a, normally closed, open to deenergize time delay 54 (limit switch 34 having returned to its normal open position). This occurrence is effective to close contacts 5412 (now open), in turn, effective to energize solenoid C. Solenoid C reverses valve 61 to relieve the air pressure from the right side of piston 67 and to shift the pressure to the opposite side thereof.

On the return stroke piston 67 is effective to drive the mold 17 to the right to its starting position.

Upon reaching the starting position the limit switch 34 is again actuated by the block 30 and the cycle just described is repeated in sequential fashion to produce a connected line of individual and separable billets.

In operation of the casting machine of the present invention, cool water is circulated through the casting machine by means of the conduits 22 and 23 and the metering box 24 is connected to a suitable source of liquid metal. A starting bar of the same general conformation of the billet line BB is inserted through the guide rolls 4848 so that its end face is approximately one inch from the face 36 of the feed tube 26 with the casting mold 17 disposed in the position shown in FIG. 2. Upon introduction of fluid metal into the feed tube, solenoid C is deenergized to admit air pressure to piston 67 of cylinder 29 whereupon the casting mold 17 moves along the guide rods 14 and 16 at a predetermined substantially uniform rate. At this time, the starting bar is securely clamped to the mold by means of the dogs 39 and 41. Correspondingly, the rams 43 and 44 are free of pressure so that the casting mold and the starting bar, locked together, may move freely to the left as viewed in FIG. 2.

Since the feed tube is securely fixed in the upright 12, the space between the right end face of the starting bar and the face 36 of the feed tube progressively enlarges and as this cavity opens up, liquid metal flows into the cavity and begins to solidify. Obviously, the longer the stroke of the casting mold the larger the length of the billet cast.

Attention is directed to the fact that there is no relative motion between the solidified metal and the mold cavity;

7 the mold cavity merely enlarges as the mold proceeds to the left and new liquid metal is introduced and solidified.

Attention is also directed to the fact that in view of this method of casting, the feed problem is simplified in that the liquid metal flows by gravity into the mold cavity and no special regulatory devices are needed for the feed system.

It is simply necessary to maintain a sufiicient head of metal in the metering box 24 to insure that the feed pipe and the mold cavity is filled. When the mold has reached the end of the desired casting stroke, there is an appropriate dwell period, such as from 4 to 20 seconds, for the purpose of allowing the billet to shrink away from the mold.

Thereafter the mold is moved rapidly back to its starting position. The rate at which the mold is returned to its starting position is 4 to 12 inches per second. Before the return stroke, the dogs 39 and 41 release the casting bar or billet line, as the case maybe, while rams 43 and 44 are pressurized. In this way, the billet line is held irnmovable relative to the base while the casting mold is returned to its starting position.

Thereafter the casting stroke is repeated sequentially as long as desired to produce a connected line of individual billets BB.

Note that as a result of the dwell period involved in shrinking the billet and in returning the mold to its starting position a cold shut or annular separation occurs between billets. This shut partially separates the billets and occurs as a result of liquid metal freezing against the annular end face 36 or" the end of the feed tube. The billets remain connected by a neck whose diameter is defined by the opening 69 of the feed tube.

A reference to FIG. 6 will disclose the general configuration of the annulus characterizing the cold shut and its relation to the central neck through which the connection from billet to billet is maintained. FIG 6 also shows a log of billets.

The central neck connecting each billet and the annular cold shut provide a convenient separation point for dividing the billet line into a short series of contiguous billets composed of any desired number of billets or into indi-- vidual billets, as desired. Ashort series of connected billets are referred to as logs in the trade.

Furthermore, attention is directed to the fact that various finishes and external surface characteristics may be obtained, depending upon the particular alloy cast, by con trolling the speed at which the castingmold progresses along its casting stroke and by controlling the dwell interval at the end of the stroke.

As stated previously, the length of the casting stroke controls the length of the billet and the billet length is indicated by the axial length of cast metal spanning two successive cold shuts.

The casting stroke and, therefore, billet lengths range from 4 to 36 inches depending upon the alloy, billet diameter and ultimate use of the metal being cast.

At this point, it is Worthy of noting that the casting process of the present invention is not related to and is distinct from those processes in which the cast cross-section is shaped by passing molten metal through an oscillating die, ie., a die that inches backand forth axially according to simple harmonic motion in the manner disclosed in U.S. Patent No. 1,088,171, issued February 24, 1914, to A. H. Pehrson.

In order to obtain uniform metallurgical properties in the cast cross-section, it is important that the mold be moved at a uniform speed during the casting stroke. The rate ofadvance of the mold during casting, although uniformior a particular alloy and diameter of cast crosssection, may range from about 5 inches per minute for aluminum alloy No. 2024 cast into billets having a diameter of 7 inches, to about inches per minute for aluminum alloy No. 2011 cast into billets having a diameter of 2 inches.

Cooling occurs constantly during the casting stroke as a result of the heat transfer effect of coolant, such as water, circulated through the core of the casting mold by means of the conduits 22 and 23. Water at about 150 F. is introduced at about 50 gallons per minute and emerges at a temperature ranging from 155 to 165 F.

To provide sufiicient time for the development of a cold shut it is necessary to hold the mold stationary at the end of the casting stroke for a definite interval of time. This interval may range from 4 seconds to 20 seconds depending upon the alloy and diameter of the billet crosssection.

Following the dwell period the billet is clutched and the mold is returned sharply to the starting position. The rate at which the mold is returned is much higher than the rate of the casting stroke and is of the order of 24 to 60 feet per minute.

The following table of representative data shows the rate at which the casting mold is advanced during the casting stroke and the interval of dwell for the particular alloys and billet diameter noted:

A unique feature of the process of this invention is that the rate of feeding of liquid metal into the mold cavity is self-regulating; no elaborate flow control system is necessary.

The feeding rate of liquid metal into the mold cavity is controlled by the rate at which the mold is moved along its casting stroke. So long as the liquid level in the metering box 24 is above the entrance to the feed tube 26, con trol of molten metal flow is controlled by the rate of advance of the casting mold.

In summary, it is well to point out that the capacity of the casting machine of the present invention while molding billets of commercial quality aluminum ranges from 220 pounds per hour to 1125 pounds per hour where billet diameters range from 2 inches to 6% inches as set forth in the following table.

Billet diameter, inches: Pounds per hour It is anticipated that a Wide variety of modifications may be devised without departing from the spirit 'and scope of the present invention.

What is claimed is:

As an article of manufacture a series of cast, metallic distinct billets defining a log of generally cylindrical billets comprising at least one cast billet of agiven length and a given diameter separably connected to a second cast billet of corresponding length and diameter by a central neck where the first and second billets uniformly cast successively over said length are joined, said billets being substantially free of cold shuts in said length and separated by an annular cold shut which extends radially to said diameter and encircles said neck whereby a weakened cross-section is developed between billets operative to render said billets readily separable.

References Cited in the file of this patent UNITED STATES PATENTS 1,088,171 Pehrson Feb. 24, 1914 1,863,371 Greene June 14, 1932 2,178,410 Tog-arty Oct. 31, 1939 2,201,024 Brown May 14, 1940 2,468,206 Keene et al. Apr. 26, 1949 2,757,444 Chace Aug. 7, 1956 2,789,327 Corley Apr. 23, 1957 2,818,616 Rossi Jan. 7, 1958 2,871,534 Wieland Feb. 3, 1959 2,882,571 Easton Apr. 21, 1959 2,975,493 Morton et a1 Mar. 21, 1961 FOREIGN PATENTS 593,852 Great Britain Oct. 28, 1947 801,819 Great Britain Mar. 22, 1956

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