US1656539A - Automatic control for centrifugal-casting machines - Google Patents

Description

Jan. 17, 1928.

M. D. SMITH ET AL AUTOMATIC CONTROL FOR CENETRIFUGAL CASTING MACHINES Filed July 2a, 1926 2 Sheets Sheet 1 R ATTORNEY Jan. 17, 1928.

M. D. SMITH ET AL AUTOMATIC CONTOL FOR CENTRIFUGAL CAS TING MACHINES I Filed July 28, 1926 2 Sheets-Sheet 2 c2133? ORNEY qnearlyauto matic as is capable of regulation,

: inventionisthe provismnof v i ae m ti lrwa hemete amay:.

Patented Jan. 17, 1928.

UNITED STATES PATENT OFFICE.

MURPHY D. SMITH, WALTER MORGAN, AND WILLIAM DAVIS MOORE, OF BIRMING- HAM, ALABAMA, ASSIGNOBS TO SAND SPUN PATENTS CORPORATION, OF YORK, N.-'Y., A. CORPORATION OF DELAWARE.

A'UTOMATIG CONTROL FOB, GENTRIFUGAL-CASTING MACHINES.

Application filed July 28, 1926. Serial No. 125,356.

This invention is an improvement in centrifugal casting methods and machines, and

' more particularly in mechanism for automatic control of the motor which rotates the mold through the movement of the mold. In casting centrifugally in refractory or sand lined molds,by the method set forth in Patents Nos. 1,620,829, 1,620,830, 1,620,831, of March 15, 1927', the molten metal is 10 charged into a tilted or inclined mold, whilethe mold is rotating at a speed insufiicient to hold the metal on the mold wall by centrifugal force. The longitudinal distribution-of the molten metal is attained by the movement of the mold to level position, and this leveling operation may be completed at or near the completion of charging, and during the rotation at a relatively low speed. That is the operations of charging and leveling are co-incident and substantially co-extensive;

After the completion of the longitudinal distribution of the molten metal, or the sub.- stantial completion, the speed of rotation of the mold is increased to a relatively high rate, suiiicient to apply the metal to the mold wall and to'hold it thereon by centrifugal initiated varies in accordance with many factors,;and it is'desirable to be able to select the moment to initiate the change from low tohig h speed, and to vary the time required for attaining the high-from the lowspeed.

.,:It is also. desirable that in the control of the relative speeds. of the motor the, human element be eliminated as far as'possible,"that start to finish. be as possible, a'nd while of a nature such thath is: that theproc ess from when oncdregulated the process will re eat indefinitely, every repetition a replica o the r sdm ne hamsm for 1 the pr mary ob ects of the present the mold at selected and different speeds during the course of the casting operation wherein the mechanism once set into operation will inaugurate and complete a sequencev of operations.

Another object is the provision of charging means for the mold operated by the movement of the mold toward level position, and co-ordinated with the operation of the controlling mechanism, so that the charging will be co-incident and substantially co-extensive with the leveling movement and related in a selected manner to the changes in motor speed.

Another object is the provision in a tilting mold normally biased by gravity to level positiomhydraulic elevating mechanism for tilting the mold, and motor speed changing means controlled by the exhaust of the hy-' draulic mechanism to first increase and afterwards reduce the motor speed.

Another object is the provision in such motor changing means of mechanism enabling the moment of initiating the increased speed and the duration of the change from low to high to be varied.

- With these and other objects in view the invention consists in the construction and novel combination'of parts fully described hereinafter, illustrated in the accompanying drawings, and pointed out'inthe claims appended hereto, it being understood that various changes in the form, proportion, size and minor .details of construction within the scope of the claims may be resorted to with-- out departing iromthe spirit of" the invention. g

In the drawings forming a part hereof:

Fig. 1 is a diagrammatic side. view ofa casting machine provided with the improved motor speedchanging mechanism.

control. I

-. Fig. 3is a plan view ofFi -2, j y Fig. 41 is a side elevation otgFigure 3.

- Fig. 5 is a side elevation of an alternate .The pr'sait ambqdim a'c of the was...

i he n -i s nesc n -W h a c st ng m chine ofthe characterishown in Patent No,

Fig.2 isfan end view of the'mechani cal f arrangement of speed geontrolling mechav swung into inclined or substantially 'hori- "preview with it their zontal position. The mold is rotatably sup- 'ported'on the carriage beneath the hood 3,

and it is'rotated by means of an electrically controlled motor 4, mounted to slide on the carriage toward and from the mold, and con led to and'released from the mold by suc i movement, the coupling mechanism being indicated generally'at5.

- The motor is controlled by a controller indicated generally a't'6, arranged at the end of the carriage, andthe controller shaft 7 has the usual hand operated mechanism 8 therefor. I

The carriage is tilte cl'or inclined by means of plungers'9 moving'in hydraulic cylinders 10, the plungers having'friction rollers 11 upon which the carriage loosely rests. \Vhen fluid under pressure as for instance water, is admitted to the cylinders by the pipeline 11, the plungers are lifted, and the carriage is inclined. The carriage moves to horizontal position by its own weight, when the cylinders are open to permit the water to discharge.

The moltenmetal is charged into the mold from a tilting ladle 12 mounted on a ladle support 13 hinged at the end of the hood remote from'the motor, and the metal is conducted from the ladle to the mold by a pouring spout, all as shown and described in the abovementioned application. The ladle is tilted by a lever 14 pivoted at 15 intermediate its ends, and having one'end in position to engaged and moved downward by the carriage as it moves to level position. Between the other end and the ladle is arranged an adjustable strut, detachably connected at its upper end with an arm 17 on the ladle, and at its lower end to the lever' by a cam plate 18, the construction and operation of which is fully described in the above mentioned application. a

The flow of the'fluid under pressure to the cylinders through the pipe line 11' is controlled by a threeway valve indicated generally at 19. This valve is interposed in the pipe betweenthe source of supply 20 and a pressure tank 21. The pressure tank is provided with a gauge 22, and a throttle valve 23 is arranged between the tank and the valve 19. A" by-pass 24 is arranged aroiind the threeway'or controlling valve 19, the-by pass havingthe usual valve 24" for varying the capacity thereof, and'a handle 19 is provided" for operating the valve-19. "A pi e 25 leadsfroin the press-are to a float tank orchamber 26, and this p" 'eis lo l flf'ifi lisfiadjiisliblefto vary thddiecliai 'ge ipaeity ofthe ifie. e a-earthenware b v'efiltiw 28,an a bleed or drain pipe 29 controll d by a valve 30, both pipes discharging into' a common drain 31. A float 32 is arranged in the float tank, and a rod or stem 33 is connccted with the float, the stem having guided movement at its top and bottom as shown. When the threeway valve 19 is opened to admit fluid under ressure to the cylinders 10, a part of the fluid passesthrou h the bypass 24 to the pressure tank 21, an from the tank by way of the pipe 25'to the float chamber26. The flow of liquid is'greater than can'discharge through the drain pipe 29, and the level of the liquid in the chamber rises, raising the float, which through the rod or stem 33 operates switches controlling the motor circuits.

- In practice, during the charging of the mold it is rotated slowly, at a speed of about 50 R. P. M. At or near the moment when the mold reaches the horizontal, the speed is rapidly increased to about 1250 R. P. M. After a relatively short time, long enough for the metal to set,the speed is decreased to about 900 R. P. M. The mold continues to rotate at this intermediates eed until the metal has sutliciently set, a ter which the Automatic'mechanism is provided for moving'the controller shaft in a direction to apt-ed up the motor at a selected moment.

his mechanism is set into motion-by. the mold ator about the time when itattains the horizontal position, and once set in motion, the mechanism continues tooperate of itself. The said mechanism includes a cylinder 34 secured tothe controller shaft, transversely thereoL-bymeans of a T bracket The ends of' the cylinder are-closed, and a-ball 36, as for instance a cannon ball of suitable site is arranged in the cylinder. The ends of the cylinder have buffers 37 for cushioning the movement of the ball, from end to endof the cylinder. With the ,controller shaft in neutralposition, the cylinder will occupy the position of Fig. 2, that end of the cyhnder' which would be moved u ward were the controller shaft handle advanced being slightly lower than the other end.

Beneath this'end of the cylinder is armotor circuit is opened,and the mold ceases to'rotate.

ranged an extension 38 of an arm 39 extending' longitudinally froin the tilting frame. A set screw 40 is threaded through the end of the extension,.in position to engage the cylinder when the arm is moved upward, thereby to tilt the'same. the us iial lo'cknuts as shown- 'and'th'e extension' is tlre'a'rhi, 'tlfe pi'votal connection bei This'set screw has pivotall'y'eonnected with'thefbody of the cylinder willoperate the controller shaft toincrease the speed, and the time re uired to pass from R. P. M. to, 1250 R. M. may be nicely regulated by the check shown in Fig. 2. r

The check is of the dash pot type, such as is used for door checks, including a fixed part 42 secured to the base 43 of the controller, and a movable part 44 connected by a link 45'with a radial arm 460m the controller shaft.- The check acts as a brake on the movement of the cylinder 34, and by adjusting therelation betweenthe fixed and movable parts of the check in a usual and well known manner, the extent of the braking action may be varied, thus to vary the adjustable stop- 47 is provided on the con- [ill trollerbase for engagementb the c linder to limit its movement toward t e vertical.

When the .controllershaft is returned to neutral position, the cylinder moves to the position of Fig. 2, and in orderto enable this movement while the carriageis horizontal, the pivotal connection between the extension 38 and thebody of the arm 39 is provided. The extension may be swung manually out of the way of the cylinder to enable the cylinder to move to the position in-the branch circuit 57 with asecond switch including a contact element 58 supported by a rod 59 having guided movement parallel with the rod 33, and a contactelement on the rod. The arrangement is such that when the float attains a predetermined height in its upward movement, the contact elements 58 and 60 touch and close the branch circuit 57. The rod- 59 is movable vertically, so that contact between the elements 58 and 60 is maintained throughout a part of the travel of the float. Vhen the elements 58 and 60 are in contact, the switch 56 in the same branch circuit is energized, and keeps open a branch shunt circuit around a portion of the motor field resistor, and allows the motor controller to regulate the speed of the motor by virtue of theposition of the controller shaft and lever. When the elements 58 and'60 are not in contact, however, the magnet coil-of switch 56 is de-energized, allowing contacts tobe made which close the shunt around a portion (which may be varied) of the field resistor, thereby imiartin a stron er field current to the motor which reduces the speed of'the motor. This is done irrespective of-the fact that the controller shaft and lever are set to such position as to normally impart a higher speed 9f rotation to the motor. f a

In order that the operator may recognize the precise moment when the frame and mold attain the horizontal, a signal is pro;

of Fig. 2. To insure that the extension will .vided, controlled by the movement of the be in operative position when the carriage again moves toward level position after 'being tilted, a cam 4 8 is provided.- This cam is a frame of right triangular shape, and is so arranged that as the carriage moves from horizontal to inclined position the extension will engage the hypotenuse of the frame, and will be returned into alihement with the body of the arm. I As previously mentioned, the float valve ,32 operates switches which control the motor circuits. One of these switches 49 is inter posed in a branch circuit 50 from the main supply circuit 51 of the motor. The switch includes a switch arm 52 pivoted at 52? normally urged or 'biased to ClI'CIllhClOSlIl position by a counterweight 53 on one end of the arm. The other end bearsagainst a stop 54 adjustably mounted;on the rod. 33, the arrangement being such that when the float moves upward, the arm may swing'under'the pull of the counterweight, to close the branch circuit 0. A magneticcontactor switch 55 its magnets'interposed'inthe branch circuit, and the cores of the magnets operate to close the main motor circuit 51 when the coils are energized." j y second magnetic conta'etor switch 56 is arranged in a, branch 57 from the main 3 d motor-circuit. Thi switch .56 is in series ruit indicated at 70.

frame or carriage 1. This signal, in the present instance an electric light 65, is inter-- rangement is such that the moment when the carriage moves into level position, or

immediately prior to the attainment of such position, the contact elements 67 and 68 will engage, closing the circuit, and displaying the signal. A suitable speed indicator 69 1s provided for indicating to theoperator the speed of the motor, and this is arranged in a convenient position forinspection, in a cir- The operation of the mechanism just described is as follows. When ready for easting, b means of the threeway valve 19 water is 'a itted to the cylinders '10, The plungers move upward, and the carnage is tilted into the position of Fig. 1. Through the bypass 24 a part of the water-passes by way or the pressure tank and the pipe. 25

to the float chamber 26,'and thefloat begins to rise. At a predetermined moment in 'therise thereof,the contacts'58- and .60 engage, after which the contact .58 moves with the contact 60,-maintaining the branch circuit 5'? closed, thezswitch bfienergized. At

about the time when the mold attains the inclined position of Fig. 1, the water level in the tank 26 isat' the level of the overflow 28, and the float is in its highest position. As the float lifts, the switch 49 operates, and the switch 55 is energized to close the main motor circuit.

The controller handle 8 has meanwhile been set at one point, and the motor begins to rotate at a speed of about 50 R. P. M. The charge is poured intdthe ladle, and the valve 19 is opened to permit the cylinders 10 to exhaust through the pipe line 11. As the carriage moves downward, the ladle is tilted, and the molten metal is discharged into the mold, the relation between the ladle and mold, and the co-ordinated movement of ladle and mold being such 'that a stream of substantially uniform volume is delivered into the mold throughout the time of its travel from inclined to horizontal position, the leveling and charging operations being co-incident, and substantially co-extensive.

At or about the moment when the mold reaches the horizontal, the extension 38 of 'to complete the speeding up from.50 R. P. M.

to 1250 R. P. M. being regulated by means of the check. The moment when the cylinder begins to tilt also may be varied by means of the set screw 40.

When the carriage and mold are in horizontal position, water no longer discharges into the float chamber. The drain valve has been set to discharge the water through the pipe 29 at a rate such that the float will reach its lowest position in a predetermined time, as for instance three and one-half minutes. When the float has moved downward. aselected distance, the contacts 58 and' 60 disengage, and the switch- 56 is operated .to close the circuit 61, shortcircuiting a portion of the motor field resistance. The field strength is increased and the motor speed is automatically synchronized with the pouring of tha metal and'the'lowering of the carriage, and that,the operation is controlled b a single mechanism, namely the valve 19. Vhilethe arrangement is su h that the operation is completely automatic and controlled by the valve 19, yet the manual control of the motor is at all time available to the operator, and may be used in emergencies V The automatic control is shown applied to a tilting casting machine, but'it is obvious that the same principle, and substan-, tially the same mechanism may be used in connectionwith a non-tilting or fixed pipe castingmachinen Such arrangement is shown in Fig. 5. In this arrangement, a hydraulic cylinder is provided, in which is arranged a plunger 76 having a lost motion connection at its uper end with one end of alever 77 pivoted at 78 near the casting machine, indicated-at 79. The plunger 7 6 is counterweighted, the weight being indicated at 80, in such manner that when the cylinder 75 is opened to exhaust, the weight will force the plun er downward in a predetermined length 0? time. A cylinder 81 corresponding in all respects to the cylinder 34, is secured to the controller, shaft 82 in the same manner as the cylinder 34: is secured to the controller'shaft 7. This cylinder has the ball 83 therein, and one end is connected by a stirrup 84;.With the lever 77 intermediate its ends and on-the opposite side of the pivotal connection from the. plunger 76.

The pipe line 74 of the cylinder 75 is connected with the same mechanism of controlling valve, pressure tank, bypass, float mechanism, and switches as is the pipe line 11 of Fig. 1. That end of the'lever remote from the plunger 76 is connected with the pouring ladle not shown, for the molten metal by the. strut 77 corresponding to the strut 16 of Figure l. The operation is substantially the same as the construction of Fig. 1. When ready for casting, the weight 80 is lifted, and descends as'the ladle empties. The sequence of operation on the part of the float, and switches is the same, and the-same results as regards motor speeds are attained, The lever 77 is connected to the cylinder 81 by a stirrup in the manner shown, so that it maybe released when returning the cylinder to horizontal position. That is the stirrup serves the same. function as the pivotal connection of the. Fig. l construction.- v 1 It .will be l evident from the description that the charging of the mold is synchronized with the change in speed, andthat in both constructions the. charging mechanism initiates. the operation of the speed changing, means. In the Fig. 1 construction the charging mechanism includes the tilting ladle, the tilting frame, and the connection between them'wherebywhen the frame is leveled the 5 Inthe I arranggment of Fig. 5, the charging mechanism is the ladle and the operating means therefor, which may be of any suitable character.

In both constructions the change in speed is related to the position of the mold and to the charging of the molten metal. In the first instance the increase in speed commences when the mold attains level position, and near the end of the charging operation. In the other instance the relation is the same and the change in speed occurs with the parts in the same relation, that is with the .mold level, and near the endof the chargingoperation. In both instances the speed changing means includes as the impelling force thereof a gravity operated plunger,-

that is a plunger biased toward downward.

movement by gravity, and hydraulic means to elevate the plunger. In the first example the mold and its support serve nit same purpose as the weight in the second example;

It will be evident from the description that the invention broadly considered is an assemblage of instrumentalities operating in cycles, for charging a mold, and for rotating the mold through a sequence of selected speeds bearing a certain relationship to the a charging operation, together with a single controllmg means for initiating the cycles. What is claimed as new is: i 1. In centrifugal. casting, a tilting mold normally biased to level position by gravity, elevating means to tilt the mold, a motor to rotate the mold, and means operated by the movement of the mold toward level positionto first increase and afterwards reduce motor, and means independent of the manual control operated by the movement of the mold toward level osition to first increase and afterwards rclhce the motor .speed.

4.. In centrifugal casting, a tilting mold normally biased to level position by gravity,

elevating means to tilt the mold, a motor to rotate the mold, means operated by the movement of the mold toward level position to first increase and to afterwards reduce the speed of the motor, and means in connection with said last named means enabling selection .of the moment when. the

increase in speed commences.

c I 5, In centrifugal casting, a tilting mold normally biased to level position by gravity, elevating means to tilt the mold, a motor to rotate the mold, means operated by the movement ofthe mold toward level position to control the speed of the motor, the

elevating means including hydraulic mech anism, and'means in connection therewith, to vary the speed of movement ofthe mold to level osition.

6. n centrifugal casting, a tilting mold normally biased to level position by gravity, elevating means to tilt the mold, a motor to rotate the mold, means operated by the movement of the mold toward level position to control the speed of the motor, the elevating .means including hydraulic mechanism, means in connection therewith to vary the speed of movement of the mold to level position, and meansto var the duration of the change from low to high speed. 7. In centrifugal casting, a tilting mold normally biased to level position by gravity, elevating means to tilt the mold, a motor to rotate the mold, a manual control for the motor, means operated by the movement of the mold toward level position to vary .the speed of the motor through a selected sequence of increase, decrease and stop,'said means independent of the manual control.

8. In centrifugal casting, a tilting mold normally biased to level osition by gravity, elevating means to tilt t e mold, a motor to rotate the mold, means to vary the speed of the motor in a selected sequence of increase, decrease and stop, and means whereby, the movement of the mold toward level position will initiate the operation of said means.

9. In.centrifug alcasting, a tilting mold normally biased to' level position by gravity, elevating means to tilt the mold, a motor to rotate the mold, means to vary the s eed of the motor in a selected sequence of increase, decrease and sto means whereby'the movement of the mol toward level position will initiate the operation of said'means, and means in connection with the speed -ment oi the mold toward level position will initiate the operation ofsaid means,- and means in connection with the speed'varying means enabling selection of the moment when the increase 1n speed commences, and

the duration of the change from the initial low to high speed.

11. -.In centrifugal casting," a tilting mold normally biased to level position by gravity,

elevating means to tilt the mold, a motor to varying means enabling selection of the r to varfthe speedof t e motor through a selected sequence of increase, decrease and s p no (i. toward level position will initiate the operationcf saidmeans, said means'includinga gravity operated acceleratin device in connection-with the controlled, an means in connection, with the speed, varying means enabling selection of the. moment whenthe increase in .speed'commences.

13! Injcentrifugal casting, a tilting mold normally biased to'level position by gravity,

el'evatin means to tiltthe mold, a motor to I rotate "t e mold, a rotatable controller for the motorpmeans to operate the conti'oller tovarythe speed of the ,motor through a se- "lec'tedsj 'uenceof increase, decrease and sto means :ilierebythe movement of theme d toward level positionwill initiate the opera- .f el operation .ofsaid means, said means includtion of said means, said means including a gravity operated accelerating device in 'con-' necticn with the. controller, and means in foo ection with thefslpeed varying means ena ling selection of t moment when the increase in .speedcommences, and the dura- ,14.In, centrifugal casting, a tilting mold tion of the fchan'ge from the initial low to normally :biased to level 'position by gravity, elevatin me a ns to tilt the mold, a motor to rotate t e mold, afrotatable controller for the motor, means to operate the controller to varythe. speed. of :th motor through a selected sequence of increase, decrease and means whereby the movement of! the toward level position will, initiate the mg a. gravity operatedaccelerating device in connection with the .c'ont'roller and means ,inconnectionwiththia speedvar 1n means L ncrease in s eed' commences, the elevating enabling selection ofthe 'inomen ..w en the means including hydraulic mechanism havj-ingan enhaust ad'ustable inca acity to enab ere ation o the;speed .o descent of the mo d. I

"15. In centrifugal mold 1 normally biased tolevel "ositionbyf avity,

elevating; means tilt e ;mold,- an means 'controlled to o ate by the movement of the mold town I level positionto rotate-the means whereby the movement of the.

mold through a sequence of selectedspeeds and to finally stop the motor.

16. In centrifugal casting, a rotatable mold, means to charge the mold including a tilting ladle delivering to the mold, and 7'0 means synchronized with the tilting of the ladle to rotate the mold through a sequence of selected speeds to a final stop, said means controlled by the charging means to operate near the end of the charging operation.

17. In centrifugal casting, a rotatable mold, means to charge the mold including a tilting ladle delivering to the mold, and means synchronized with the tilting of the ladle to rotate the mold through a sequence of selected speeds to a final stop, said means controlled 1) the charging means to operate near the en of the charging operation, the

mold pivotgd near one end, elevating mechanism at the other end to incline the mold prior tothe charging operation, and means operated by the return of the mold to level position to tilt the ladle.

18. In centrifug l casting, a tilting mold, a motor to rotate the mold, a controller for the motor, normally inoperative gravity operated mechanism to move the controller in a direction to speed up the motor, means operated by the mold near the end of its leveling movement to move said means into operative position, and other mechanism controlled by the descent of the mold to 510w the motor after a selected period andto afterwards'stop the motor.

19. In centrifugal casting, a rotatable mold, a motor for rotating the mold, a gravity operated accelerating 'device to speed up the motor, mechanism to charge the mold,

andmeans operated by the charging mechanism to start theaccelerating device.

20-. In centrifugal casting, a rotatable mold, a motor for rotating the mold, a gravity operated accelerating device to speed u the motor, mechanism to charge the mol means operated bIv the charging mechanism to start the acce crating device, and other means operated thereby to'reduce the speed ofthemotor and to finally stop the same.

21. In centrifugal casting, a rotatable tilting mold, a m'otorfor rotating the mold,

'means to tilt the mold, the mold being gravity operatedto level position, a'gravit operated accelerating device to speed up t e motor; means operated by the mold near the end of its movement toward level position to start the accelerating device, and other'means operated by said, movement of the-moldto reduce he speed of the motor and' to finally stop the same.

, 22. In centrifugal casting, a rotatable tiltf I25 ing mold, a motor-for rotating the mold, meansto tilt the mold,the mold being leveled gravity, a gravity ..operated accelerating device tospeed up the motor, a ladle for charging the mold, a connection between the" mold and the ladle to empty said ladle while the mold is returning to level position, means operated by the mold near the end of its leveling movement to start the accelerating device, and other means Operated by the mold in said movement to reduce the speed of the motor and finally stop the same.

23. In centrifugal casting, a rotatable mold, an electrically controlled motor for rotating .the mold, a rotatable'controller for the motor, a gravity operated accelerating device for the controller to speed up the motor, charging mechanism for the mold, means operated by the charging mechanism to initi ate the operation of the controller accelerating device, and other means operated thereby for opening the motor circuit at a selected moment.

24. In centrifugal casting, a rotatable mold, a motor for rotating the mold, mechanism controlling the motor through a regular sequence of selected speeds to a final stoppage thereof, charging mechanism for the mold operating in synohronism with the m0- tor speed controlling means, and means whereby the charging mechanism will initi-' ate the operation of. the speed controlling means near the end of the charging opera tion.

25. Incentrifugal casting, a rotatable mold, a motor for rotating the mold, mechanism controlling the motor through a regular sequence of selected speeds to a final stoppage thereof, charging mechanism for the mold operatingin synchronism with the motor speed controlllng means, and means whereby the charging mechanism will initimeans near the end of the charging opera-- tion, the motor speed controlling means ineluding a plunger normally biased to down- Ward movement by gravity, and hydraulic mechanism for lifting the plunger.

26. In centrifugal casting, a rotatable mold, a motor to rotate the mold, mechanism controlling the motor to cause the same to rotate the mold through a sequence 'of changes in speed'to a final stop, said mechanism operating automatically when started and independently of the motor and the mold, and a single means to start the-operation.

27. In centrifugal casting, a rotatable tiltable mold, instrumentalities operating to charge, level and rotate the mold, mechanism coordinating said instrumentalities and constraining them to operate in a selectedcycle, and a single means for initiating a c cle.

28. In centrifugal casting, a rotatable tiltable mold, instrumentalities operating to charge, level and rotate the mold through a selected sequence of speeds to a final stop, mechanism coordinating said instrumentalities and constraining them to operate in aselected cycle, and asingle means to initiate the cycle.

Signed at Birmingham, in the county of Jefferson and State of Alabama this 19th day of July, A. D. 1926.

MURPHY D. SMITH. WALTER MORGAN. WILLIAM DAVIS MOORE.

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