Patent Publication Number: US-3877620-A

Title: Metal valve for battery grid casting machine

Description:
United States Patent Rader Apr. 15, 1975 Primary Examiner-Robert B. Reeves Assistant Examiner-David A. Scherbel [75] Inventor: Robert R. Rader, Port Huron, M1ch. Attorney, Agent or Firm BameS, Kisseue, Raisch &amp; [73] Assignee: Wirtz Manufacturing Company, Choate Inc., Port Huron, Mich. 22 Filed: Jan. 23, 1974 [571 f d ABSTRAZT d 4 A valve or ispensing a pre etermine amount of [21] Appl&#39; 435830 molten lead to the mold of a battery grid casting machine has two tubular housings arranged in telescoping 52 us. c1. 222 537; 222/559; 251/347; relation with their axes extending vertically The 251/351 upper housing is fixed and has a feed line for molten [51] Int. Cl B22d 37/00 metal Connected thereto- The lower housing is verti- [58] Field of Search 164/337; 251/147, 347, Cally movable and has a lead discharge line extending 251/351, 222/507, 509, 559, 537 therefrom. A ball valve member is loosely retained on a pedestal in the lower housing and is arranged to seal 5 References Cited with an annular valve seat in the upper housing to UNITED STATES PATENTS control the flow of lead in response to vertical movement of the lower housing. 953,154 3/l9l0 Pr1de, lr. 251/347 X 3,786,962 1 1974 Van Linder 222/559 15 Claims, 6 Drawing Figures I! 56 a 0 A I I l 45 II [III 1, HI I2 2 4g 44 1 r Z0 METAL VALVE FOR BATTERY GRID CASTING MACHINE This invention relates to battery grid casting machines, and. more particularly, to a valve mechanism for periodically dispensing a predetermined amount of molten metal into a mold filling ladle.  
  Battery grid casting machines necessarily employ some form of means for dispensing a predetermined amount of molten metal into a mold filling ladle during a predetermined time interval of each cycle of the machine. Such means frequently take the form ofa molten metal valve. The valve controls the amount of molten metal discharged to a ladle. During each cycle of the machine, after the mold closes, the ladle is tipped or rocked to pour the required charge of molten metal into the cavity of the closed mold. Valves of this type must be capable of operating freely without undue friction in order to dispense the requisite charge of molten metal at the proper time. This is particularly true where the quantity of metal dispensed is controlled by opening the valve a predetermined extent for a predetermined time period. With some valve constructions this is difficult to achieve in view of the fact that the temperature of the molten metal flowing therethrough (for example, 700 1.000 F.) tends to produce distortion and cause misalignment and malfunctioning of the valve. It thus becomes important that such valves be constructed so that their proper functioning is not adversely affected by relatively high temperatures.  
  The present invention has for its object the provision of a molten metal valve of the type described which achieves the aforementioned objectives.  
  More specifically, the valve of the present invention embodies upper and lower telescopically engaged tubular housings which are axially movable relative to one another. The upper housing is connected to a source of molten metal, such as a lead pot, and the lower housing discharges into a mold filling ladle. The two housings are dimensioned to have a slight clearance between their telescoping side walls to compensate for possible distortion and misalignment due to heat and assembly tolerances. A valve seat is mounted in the upper housing for cooperation with a spherical ball valve member retained in the lower housing. The ball valve member is supported for lateral rolling movement on a flat hard metal surface so that it will align itself readily with the valve seat when the two housings are moved relatively toward one another. The ball valve member is surrounded by an open retaining cage which limits the lateral excursion of the ball so that it is at all times located in a self&#39;aligning position relative to the valve seat.  
  Other objects and features of the present invention will become apparent from the following description and accompanying drawings, in which:  
  FIG. I is a fragmentary perspective view of the valve and valve operating mechanism of the present invention;  
  FIG. 2 is a fragmentary elevational view of a portion of the mechanism shown in FIG. 1;  
  FIG. 3 is a vertical sectional view of the valve in the closed position;  
  FIG. 4 is a view similar to FIG. 3 and illustrating the valve closed with the valve components in a slightly misaligned condition;  
  FIG. 5 is a sectional view along the line 55 in FIG. 3; and  
  FIG. 6 is a generally diagrammatic showing of the molten metal feed system for the machine.  
  Referring first to FIG. 6, a heated lead pot is shown at I0. Within the lead pot there is arranged a pump 12 suitably driven by a motor 14. The outlet of pump 12 connects with a vertically extending feed line 16 having an inverted U-shaped return bend 18 connected with a downwardly extending return line 20, the lower end of which discharges into lead pot 10. Just below the U- bend 18 a branch feed line 22 connects with feed line I6. Line 22 extends to a molten metal valve, generally designated 24, having a discharge line 26 which discharges into a ladle 28. Ladle 28 is arranged to be tipped during each cycle of the machine to discharge a predetermined amount of molten metal into the grid mold. The extent of ladle tipping is such as to retain a substantial amount of molten metal in the ladle at all times. The ladle charge is replenished with each opening of valve 24. A fitting 30 connected with U-bend 18 is provided for supplying inert gas to the molten metal flowing through lines 16, 20 and 22. In operation motor 14 and pump 12 are operated continuously to feed molten metal upwardly through line 16 and to line 22. The excess metal returns to the lead pot through return line 20. It will be observed that in the arrangement illustrated the molten metal at valve 24 is subjected to a constant pressure head. After each opening of valve 24 ladle 28 tips to discharge into the grid mold a predetermined portion of the molten metal therein.  
  Referring now to FIGS. 1 and 2, the mechanism for supporting and operating valve 24 is illustrated. This mechanism includes a pedestal 32 suitably mounted on a frame member 34 of the grid casting machine. On the upper end of pedestal 32 there is mounted a cross arm 36 carrying at one end a vertical mounting plate 38 and a horizontally extending support bar 40. A pneumatic cylinder 42 is mounted on mounting plate 38 by an L- shaped bracket 44. An adjusting screw 46 is employed for vertically shifting cylinder 42. A piston rod 48 projects upwardly through the upper end of cylinder 42. An air line 50 is connected to the lower end of cylinder 42. Cylinder 42 is operated by a timer-controlled solenoid valve 52.  
  A threaded bushing 54 extends downwardly through support bar 40 in axially aligned relation with cylinder 42. The end of support bar 40 through which bushing 54 is threaded is axially split and provided with a clamping screw 56. After bushing 54 is vertically adjusted to the desired position, screw 56 is tightened to lock bushing 54 in its adjusted position. The free upper end of piston rod 48 is provided with a vertically adjustable tip 58 which normally abuts the enlarged head 60 of a vertically shiftable pin 62 extending through bushing 54. The extent to which pin 62 can shift vertically upwardly from the position shown in FIGS. 1 and 2 is limited by the lower end face of the threaded shank 64 of bushing 54.  
  Upstanding arms 66 are securely mounted on cross arm 36 intermediate its ends and a lever 68 is pivoted between the upper ends of arms 66, as at 70. At one end lever 68 carries a weighted member 72. At its opposite end lever 68 is formed with an upwardly opening, U-shaped fulcrum 74. A vertical link 76 has its upper end pivotably supported in fulcrum 74 by means of a pivot pin 78. A counterweight is fixedly mounted on link 76 adjacent pivot pin 78.  
  Referring now to FIG. 3, valve 24 comprises an upper housing 82 and a lower housing 84. Upper housing 82 is in the form of an inverted cup which is fixedly mounted on the other end of cross arm 36 by a mounting plate 86. Lower housing 84 is likewise of cup shape and is fixedly mounted to the lower end of link 76. For purposes of illustration, link 76 has been displaced circumferentially in FIGS. 3 and 4 relative to its position as illustrated in FIGS. 1 and 2. Housings 82, 84 are telescopically engaged as illustrated, the inner diameter of housing 82 being slightly larger than the outer diameter of housing 84 so that there is a slight clearance 88 between the side walls of these housings. This clearance is preferably on the order of 0.0l 0.020 inches. In practice the pivot pin 78 (by means of which link 76 is fulcrumed on lever 68) is axially aligned with the center axes of housings 82, 84. Likewise, counterweight 80 is designed and arranged to maintain the lower housing in a generally co-axially aligned relation with the upper housing.  
  Within upper housing 82 there is arranged a fitting 90 which extends vertically through the end wall of the housing. The upper end of fitting 90 is threaded as at 92 for connection with the feed line 22 from lead pot l0. Fitting 90 has a central passageway 94 which terminates at its lower end in a threaded opening 96. Within opening 96 there is threaded a valve seat member 98, the vertical position of which is determined by the thickness of a spacer 100. Valve seat member 98 is centrally apertured and in open communication with the central passageway 94 of fitting 90. At its lower end member 98 is formed with an accurately ground annular seat 102. Valve seat member 98 is formed ofa wear and temperature resistant metal, such as stainless steel or lllium B (a nickel-chromium-molybdenum-copper alloy).  
  Lower housing 84 has a radially inclined bottom wall 104. the lowermost portion of which is in open communication with discharge line 26 through an aperture 106. Within bottom wall 104 there is embedded a pedestal 108 formed or a hard, temperature-resistant metal. The upper end of pedestal 108 is ground with a smooth flat face 110 which is perpendicular to the central axis of housing 84. On the flat face 110 of pedestal 108 there is supported an accurately spherical carbide ball 112. Ball 112 is free to roll on flat face 110 within the limits defined by a retaining cage comprises of four upstanding pins 114. The radius of the circle defined by the radially innermost portions of pins 114 exceeds the radius of ball 112 by at least the radial clearance space 88 between the side walls of housings 82, 84. Pins 114 limit the lateral excursion of ball 112 to a distance less than the radius of annular valve seat 102. Thus, regardless of the extent of vertical misalignment between housings 82, 84, ball 112 will always align itself properly and seal with the annular valve seat 102.  
  It is apparent that valve 24 is opened and closed by shifting lower housing 84 vertically. The valve may be opened during each cycle of the machine by any suitable means. In the arrangement illustrated the means for operating the valve includes a switch 116 which is arranged to be actuated by any component of the battery grid casting machine which moves in timed relation to the opening and the closing of the mold. For example, switch 116 can be actuated by a bar or rod connected to the movable section of the mold. Switch 116 actuates a preset timer which energized solenoid 52 for a predetermined period of time. For example, if each cycle of the machine has a duration of about 3 seconds, then valve 24 may be opened for three-quarters to one and one-quarter seconds. When solenoid 52 is energized piston rod 48 is displaced upwardly to an extent such that the enlarged head 60 of pin 62 engages the lower end face of the threaded shank 64 of bushing 54. The upper end of pin 62 engages the lower end face of the threaded shank 64 of bushing 54. The upper end of pin 62 engages the bottom face of weight 72. Weight 72 in combination with tension spring 118 normally rocks lever, 68 in a counterclockwise direction, thus urging ball 112 to engage valve seat 102 and thereby effectively close the valve. In order to insure a positive seal at valve seat 102 the vertical position of cylinder 42 is adjusted by screw 46 so that the upper end of pin 62 is spaced slightly below the bottom face of weight 72 when the valve is closed. When cylinder 42 is actuated pin 62 engages weight 72, pivots lever 68 in a clockwise direction, and, thus, shifts lower housing 84 downwardly to unseat ball valve member 112. The extent to which lower housing 84 is shifted downwardly may be adjusted by adjusting bushing 54 in support bar 40 so as to vary the vertical distance between the enlarged head 60 of pin 62 and the lo er end face of the threaded shank 64 of bushing 54. Spring 118 prevents oventravel in the valve opening direction.  
  When lever 68 is rotated about pivot pin in a clockwise direction lower housing 84 is displaced vertically downwardly and is retained in the lowered position for a predetermined period of time as determined by the setting of the timer which controls solenoid 52. During this interval of time the molten metal in feed line 22 discharges downwardly through valve seat member 98 and into the lower housing 84. The inclined bottom wall of housing 84 causes the molten metal to flow directly to the discharge line 26. As shown in FIG. 1, the outlet of discharge line 26 is always located below the level 120 of the molten metal in ladle 28. Air is thus prevented from entering the-valve through discharge line 26. This will tend to prevent the accumulation of dross in the molten metal. The prevention of dross formation is substantially enhanced by the introduction of inert gas to the space enclosed by housings 82, 84 through a conduit 122 connected with the upper housing 82, as at 124. While a small amount of inert gas may escape from within the housings at the clearance space 88 between the housings, this amount is not substantial since, as pointed out above, the clearance space 88 only amounts to about 0.0l0 0.020 inches.  
  Although the clearance space 88 is of the magnitude mentioned above, it is sufficient to compensate for the misalignment which may occur between the housings 82, 84 due either to heat or to assembly tolerances. In any event, even under such conditions of misalignment ball 112 is designed to seat and form a perfect seal with annular valve seat 102. For example, in FIG. 4 a condition of misalignment of the two housings is illustrated. In this particular showing lower housing 84 is slightly off center relative to upper housing 82 and is slightly cocked in a clockwise direction. Under this condition when solenoid 52 is de-energized lower housing 84 shifts upwardly under the influence of weight 72 and spring 118. As soon as the surface of ball valve 112 encounters a portion of annular valve seat 102 the ball is free to roll laterally on the flat face of pedestal 108 so that is aligns itself concentrically with seat 102 and,  
 thus, results in a perfect seal. It will be further appreciated that distortion due to heat is minimized by the valve construction shown. The outer diameter of fitting 90 is sufficiently smaller than the inner diameter of housing 82 so as to provide an annular space therebetween for the introduction of inert gas. Likewise, as pointed out above, the bottom wall of housing 84 is inclined. Thus, as soon as the valve closes all of the molten metal is immediately discharged therefrom and there is no stagnant pool of molten metal which accumulates or remains in the valve.  
  It will be appreciated that in addition to the abovementioned advantages, the valve of this invention is also constructed to facilitate servicing and cleaning thereof. To obtain consistently reliable operation molten metal valves of the type described must be cleaned periodically. The present valve can be disassembled for cleaning without requiring the use of tools. To disassemble the valve it is merely necessary to lift weight 72 and, thus, lower housing 84 sufficiently to disengage it from within housing 82. Thereafter link 76 is raised to release it from the upwardly opening fulcrum 745 and the two sections of the valve are accessible for cleaning.  
  It will also be understood that, although the operation of the casting machine is cyclical, it is not absolutely necessary that the molten metal valve be opened and closed during each cycle of the machine. If desired, the valve can remain open continuously during machine operation and the rate of metal flow controlled by a metering valve in the molten metal feed line. With this mode of operation it is nevertheless essential that the valve produce a fluid-tight seal when it is closed periodically upon an intentional stopping or interruption of the machine operation for servicing and the like.  
 I claim:  
  1. In a battery grid casting machine of the type wherein a mold is opened and closed with each cycle of the machine, a valve for dispensing molten metal to a mold filling ladle comprising, upper and lower tubular housings having their central axes extending generally vertically in generally coaxially aligned relation, the lower end of said upper housing and the upper end of said lower housing being in open communication with one another and telescopically engaged, one of said housings being supported in fixed position on the machine and the other being mounted on the machine for vertical movement, means for shifting said movable housing vertically, said upper housing having a bore therein which opens vertically downwardly, said bore terminating at its lower end in an annular valve seat which is generally co-axial with said upper housing, said valve seat being disposed below said upper end of said lower housing, an inlet conduit for molten metal connected with said bore, said lower housing having an upstanding pedestal therein, said pedestal having a generally flat upper end face lying in the plane perpendicular to the axis of said housing, a spherical ball resting on said upper end face of said pedestal and being free to roll laterally thereon to a limited extent so as to readily align itself concentrically and seal with said annular valve seat when said movable housing is shifted vertically in a direction which moves said ball and valve seat relatively toward each other, means forming 21 molten metal outlet in said lower housing at a level below said ball whereby, when said movable housing is shifted vertically to unseat said ball, the molten metal flows downwardly by gravity through said outlet means, and an open cage surrounding said ball and limiting the lateral excursion thereof on said pedestal to a distance less than the radius of said valve seat.  
  2. The combination called for in claim 1 wherein the radial dimensions of said two housings are such as to provide a slight radial clearance between the telescoping portions thereof and thus permit a slight axial misalignment of said portions without frictional contact therebetween when said movable housing is shifted vertically.  
  3. The combination called for in claim 2 wherein said cage means permits lateral excursion of said ball on said upper end face a distance at least equal to the clearance between the telescoping portions of said housings.  
  The combination called for in claim 2 wherein said cage means comprises a plurality of pins spaced circumferentially around said ball and defining a circle having a diameter slightly larger than the diameter of said ball.  
  5. The combination called for in claim 4 wherein the space cccupied by each pin is substantially less than the space between adjacent pins so as to not substantially impede the flow of molten metal from the lower end of said bore to said outlet.  
  6. The combination called for in claim 2 wherein said upper housing is fixed and said lower housing is movable.  
  7. The combination called for in claim 6 including a vertically extending fitting in said upper housing, said fitting having an outer diameter less than the inner diameter of said housings so as to provide an annular space between said fitting and the side walls of said housings and an inlet conduit for inert gas on said upper housing discharging into said annular space.  
  8. The combination called for in claim 6 wherein said lower housing is telescoped into the lower end of said upper housing.  
  9. The combination called for in claim 6 wherein said inlet conduit is connected with a source of molten metal at a constant pressure head and means for moving said lower housing downwardly a predetermined distance at regular intervals for a predetermined period of time for dispensing a predetermined charge of molten metal during each cycle of the machine.  
  it). The combination called for in claim 6 including a generally horizontally disposed lever supported for pivotal movement in a vertical plane, said lower housing being supported by a portion of said lever remote from the pivotal support of said lever, said means for shifting said movable housing comprising means for pivoting said lever.  
  ll. The combination called for in claim 10 including a generally vertically extending link fixedly connected to and extending upwardly from said lower housing, said link having its upper end pivotally connected with said lever.  
  12. The combination called for in claim 11 wherein said pivotal connection between said link and lever intersects the vertical central axes of said housings.  
  T3. The combination called for in claim l1 wherein said pivotal connection between said link and lever comprises an upwardly opening fulcrum on said lever and a pivot member on said link seated in said fulcrum.  
  M. The combination called for in claim 1 wherein said lower housing has a radially inclined bottom wall,  
  7 8 said outlet registering with the lower portion of said 15. The combination called for in claim 14 including bottom wall so as to prevent the formation ofa stagnant a discharge conduit extending downwardly from said pool of molten metal at the lower end of said lower outlet to a ladle positioned at a level below said valve. housing.