US3056179A - Control device for a molten-metal pouring ladle in a centrifugal casting machine - Google Patents

Description

Oct. 2, 1962 P. E. LORANG 3,056,179

CONTROL DEVICE FOR A MOLTEN-METAL POURING LADLE IN A CENTRIFUGAL CASTING MACHINE Filed July 15, 1960 s Sheets-Sheet 1 III I m E i I!!! If! 35?? V mom! mm om u mm vm um i x E & M T J JhVQnhH" Edouard ZORANG' rmc 7 S r g mm Q k\ mm ou Oct. 2, 1962 P E LORANG 3,056,179

CONTROL DEVICE FOR A MOLTEIN-METAL POURING LADLE IN A CENTRIFUGAL CASTING MACHINE Filed July 15, 1960 3 Sheets-Sheet 3 w-a' m AH'orm u 3,056,179 CONTROL DEVHCE FOR A MOLTEN-METAL PQUR- ING LADLE KN A CENTRIFUGAL CASTING MACHINE Pierre Edouard Lorang, Nancy (Meurthe-et-Moselle), France, assignor to Compagnie de Pont-A-Mousson, Nancy (Meurthe-et-Moselle), France, a French body corporate Filed July 15, 1960, Ser. No. 43,168 Claims priority, application France Mar. 25, 196i) 8 Claims. (Cl. 22-79) The present invention relates to the casting of castiron or another molten metal in centrifugally casting machines for pipes and similar tubular articles, and more particularly, to a control device for high-capacity pouring ladles or baskets of the type involving a succession of tippings separated by stops and partial return motions, whereby several pipes can be sequentially cast from a single molten-metal feed previously poured into the ladle, i.e. in the course of a single pouring cycle.

It is known that the pouring speed for a casting ladle of this type, from which depends the pouring rate of the metal into the centrifugal rotary mold, is adjusted such as to obtain pipes or other tubular articles having a uniform thickness and a well-specified weight confined between narrow limits. It results from the foregoing that:

On the one hand, the beginning and the termination of the metal pouring step into the mold have to be most accurately initiated,

And, on the other hand, between the beginning and the termination of said pouring step, the metal feed rate has to be constant and readily reproducible, where the production is to be conducted on an industrial scale.

With respect to the first aforesaid condition, means have already been provided for imparting to the ladle, before and after each successive pouring step, respectively, a forward impulsion for instantaneously initiating the pouring, and a backward motion or -backfall for abruptly interrupting the same, as well as means for adjusting with respect to the time factor, the tipping-over motion of the ladle starting from the end of said impulsion and the simultaneous initiation of the pouring, i.e. from the beginning of the casting proper, these means leading to the desired results, provided the conditions of the initial filling and of the level of the molten metal in the ladle compared with the bottom of the ladle at the end of each impulsion remain always the same.

As to the second aforesaid condition, viz: constant pouring rate, it would obviously be desirable that the casting ladle should preserve, from one cycle to the next, an absolutely constant capacity and, the more so, crosssection, such that at a given tipping speed, the pouring rate of molten metal should always be the same. However, this condition is practically impossible to fulfill, owing to the more or less regular wear of the refractory lining of the casting ladle and the slag and dross deposits on said liner. These surface unevennesses of the liner also lead to slight variations in the cast-iron level in the ladle at the termination of successive impulsions relative to the bottom of the ladle.

The object of the present invention is to provide a control device of a tiltable feed ladle of the aforesaid known type, wherein each feeding of the ladle or basket can be followed by a cycle comprising a plurality of sequential casting steps, said control device being improved in that it enables the pouring rate and the amount of poured molten metal to be automatically maintained at a constant level and be accurately reproduced from one casting cycle to the next, irrespective of the internal-surface irregularities of the casting ladle.

States atent O "ice This control device, which is of the type including a hydraulic jack means adapted to tilt or rock the ladle about the rotational axis thereof, comprises in combination with said jack means: two electric pumps, one for pouring and the other for impelling, these pumps having parallel outputs into said jack; two independent electric circuit means supplying said electric pumps; a photoelectric cell sensitive to the appearance of molten metal at the pouring edge of the ladle; means controlled by said cell for rendering inoperative from the moment of said appearance the impelling electric pump; a plurality of rheostats connected in the supply circuit of the pouring electric pump, said rheostats being adapted to effect an individual speed regulation thereof for a given fraction or portion of the total tilting stroke of the ladle; and cam means integrally rotated with the ladle to individually and successively operate each of said rheostats in order to adjust at will in each fraction the drive speed of the pouring electric pump.

Owing to this arrangement:

On the one hand, at the initiation of each individual casting step, both electric pumps discharge in parallel into the tilter jack and, owing to the large output provided thereby, the initial tilting is rapid and supplies the required impulse, which is discontinued as soon as the molten metal in the ladle reaches the pouring edge thereof, due to the operation of the cell;

And on the other hand, from then on, it becomes possible in the course of a first casting cycle to check on the produced pipes the results of said casting, individually for each portion or fraction of the ladle tilting motion, and to remedy to any departing from the desired weight of the product pipe in either direction, by effecting an individual adjustment of the rheostat associated with this particular portion of the casting, whereby in all subsequent casting cycles, said rheostat having thus been adjusted at the end of the first cycle, will ensure that the particular portion of the casting to which it is associated will be correctly executed.

Obviously, said device and the associated ladle .are adapted for casting in each cycle a number of pipes which is equal or lower than the number of provided rheostats, i.e. of tilt portions. In the former case, a single rheostat provides for the adjustment of the casting of all the pipes of the same order during each casting cycle; in the latter case, the pipe of a given order in each casting cycle is subjected to adjustment by a plurality of rheostats.

The invention further contemplates the provision of a centrifugal casting unit for pipes and other tubular articles, of the type including a rotary mold and a casting ladle, and provided with the aforesaid improved control device.

Further features of this invention will become apparent from the ensuing description, when read in connection with the accompanying drawings, given merely by way of example and in which:

FIG. 1 is a diagrammatic view, seen before the casting,

' of the improved control device for the casting ladle;

FIG. 2 is a view partly in transverse elevation and partly in section of the casting ladle along line 2-2 of FIG. 1. FIG. 3 is a diagram of the electric circuit means'for the control device of the casting ladle;

in FIGS. 1 to 4, the invention is applied to a casting ladle or basket 1 having substantially the shape of a cylindrical sector of large capacity, able of containing cast-iron or another liquid metal In in an amount suflicient for the successive castings of a plurality of pipes, e.g. six, these six casting operations forming what will be referred to as a casting cycle.

This basket 1 comprises a cylindrical wall 2 (FIGS. 1 and 2) of an axis XX, two plane circular lateral sectors 3, parallel to each other, and a plane wall 4 affording at the upper portion thereof, intermediate the two circular sectors 3, a pouring spout 5.

This basket is exteriorly provided, on its side walls 3 and adjacent the pouring spout 5, with a pair of trunnions 6 of axis XX and rotating in bearings carried by parallel uprights 7 forming the frame of the basket. One of the trunnions 6 has keyed at the end thereof a circular cam member 8 (FIGS. 1, 2, having formed in the periphery thereof two notches 9 and 9a whose function will be made clear later on.

Under the pouring spout 5 of the basket is provided an overflow 10 extending into a channel member 11 overbearingly mounted on a frame 12. This channel 11 is adapted to supply with cast iron the mold 13, rotatable about a substantially horizontal axis W-W of the centrifugal casting machine. This mold 13 is rotatably mounted within the movable part M of the machine, said part forming around the mold 13 a jacket 14 and rolling by means of rollers 15 on a rolling track 16 parallel to the channel 11; it is capable of being reciprocated together with the mold, e.g. by means of a hydraulic jack 17 having a piston member 18 and a rod 19 connected by an extension arm 20 to the unit 14.

For the rocking drive thereof, the basket 1 is combined with the hydo-electric control device, embodying the hydraulic jack V, and improved in accordance with the invention.

The basket 1 is provided at the lower portion of its cylindrical surface 2 with a stirrup 21 having pivotally mounted thereon the end of the rod 22 of the piston 23 of the single-acting jack V. The lower end of the jackcylinder 24 is articulated about a pin 25 on a stirrup 25a secured on the ground in a position such that the jack is slightly tilted to the vertical along a direction substantially tangential to the cylindrical surface 2, when the basket is in its feeding position prior to the casting step (FIG. 1).

The lower portion of the jack casing 24 has a duct 26 extended thereinto. This duct is connected to a first selector S of the three-positional slide-valve 27 type, which is for example hand-actuated as a function of the longitudinal shifts of the movable part M of the centrifugal machine. This selector has further connected thereto,

, on the one hand, an oil pressure inlet pipe 28 extending from an electric pump P referred to as pouring pump, which sucks in this oil through a pipe 29 from a tank B, and on the other hand, a pipe 30 discharging into said tank.

In the median position, the valve 27 plugs the pipes v 28 and 30. Jack V is then neither fed nor discharging;

its piston and hence the basket 1 remain stationary, this being the inoperative position illustrated in FIG. 1.

In its outer-most left-hand position, the valve 27 establishes communication between the pressure oil-inlet pipe 28 with the pipe 26. The piston 23 of jack V is then set on its upward stroke and lifts the basket 1 through the piston-rod 22, said basket being then rocked or tilted about the axis XX in the direction shown by arrow 1"; this position will be termed the pouring position.

Finally, in its outermost right-hand position, the valve 27 brings into communication the pipe 26 with the discharge pipe 30, this being the lowering position of the basket, i.e. wherein it is rotated in the direction opposite to the arrow F.

The pipe 26 has connected therewith in parallel a bypass 311 leading to a three'way valve J of the type comprising slide 32, able to assume two positions. This slide is extended beyond the valve body, to the left, by means of a rod 33 ending by a flange or collar 34 and, to the right, by a rod 35 attractable by a solenoid E against the urging of a spring 36 coiled round the rod 33 and compressed between the valve body and the flange 34-.

One of the three ways afforded by the valve J consists of a duct 31; the two other ways are respectively: a duct 31a connected to a further three-way selector S and a discharge duct 39.

The selector S which is similar to the selector S is specifically designed such that the slide 27a thereof for-ms an extension of the slide 27 of selector S being integrally movable therewith. This selector S has extended thereint-o an oil-pressure inlet pipe 37 from an electric pump P referred to as impelling pump, which sucks this oil through a pipe 38 from the tank B; a duct Stia is adapted to return this oil from theselector S into the tank B. Pipes 31a, 37 and 30a are located in relation to the selector S in a manner similar to the location of the pipes 26, 28 and 30 with respect to the selector S When the solenoid E is energized, the slide 32 of valve J is in its right-hand position, the pipe 31 connected with the jack V is plugged, whereas the discharge duct 31a of the pump S across the selector S is in communication with the discharge pipe 39. This position is the inoperative or neutralized position of the pump S When the solenoid E is no longer energized, the slide 32 is returned leftwards by the spring 36; the discharge pipe 31a of the pump S across the selector S is then set into communication with the jack through the pipe 31; while the discharge pipe 39 is plugged. This is the operative position of the pump S (FIG. 1).

The pipe 26, which is connected with the jack V, has further connected in parallel therewith, adjacent the inlet port of this pipe 26 into the jack, a by-pass 40 connected to a valve K having a two-positional slide 41. From this valve K extends a discharge pipe 42. The slide 41 is extended beyond the valve body K, to the right, by a rod 43 ending with a flange 44 and, to the left, by a rod 45 attractable by a solenoid E against the opposition of a spring 46 coiled around rod 43 and compressed between the valve body K and the flange 44.

When the solenoid E is energized, the slide is in its left-hand position, the pipe 40 and hence the pipe 26 communicate with the discharge pipe 42; this is the exhaust position of the jack V resulting in the lowering of basket 1.

When the solenoid E is not energized, the slide 41 is returned to the right by the action of spring 46 and, in the latter position, the pipe 49 is clear of the discharge pipe 42.

The hydraulic unit which has just been described is combined with the following electrical device (FIGS. 1, 3 and 4).

A main two-wire electric circuit 47 (FIG. 1), connected with a DC. supply U, has shunted therefrom a two-wire supply circuit 48 for the solenoid E The circuit 48 is controlled by a contactor C whose closing corresponding to energization of the solenoid, is contrlled by a phtocell 49 arranged in front of the pouring spout 5 of the basket 1 and responsive to infra-reds transmitted from the molten cast-iron, when it appears at the spout 5. To this end, the photocell 49 is, as known per se, series connected at y, z with a micro-relay 50 of a lowcurrent electric circuit. This micro-relay is adapted to close a contactor C of a higher-current circuit supplying a relay 51 which in turn acts on the contactor C The solenoid E is fed by a two-wire circuit 52 connected with the main circuit means 47 and controlled by the member C of a double contactor C C which may for instance be manually actuated.

The pouring motor pump P has electric current supplied thereto through a two-wire circuit S in parallel with the main circuit 47. This circuit 53 includes in series a rheostat R for adjusting the basic speed of the motor of the electric pump P and a plurality of precision adjusting rheostats on either side of this basic speed, e.g.. six rheostats R R R These precision rheostats adapted to adjust the rotational speed of the basket in relation to the surface irregularities thereof (slag deposits or, on the contrary, wear of the refractory liners), with the view to maintain the flow rate of the cast iron at a constant level, can be operated in turn, the functioning of one of them precluding the operation of any other, the means for achieving said result being explained later on. Each of these six rheostats corresponds to one sixth of the total rotational angle of the basket.

The circuit 53 is further disconnectable by portion C of the double contactor (C -C said portion C being connected in series with the rheostats R R upstream thereof relative to the connection point with the main circuit 47.

The conactors C and C are coupled in such a way that when one of them is open, the other is closed and vice-versa.

Each of the rheostats R R is shunted by means of a lead 54-, having series-connected thereon a contactor 1,, I or I These contactors are controlled by relays M M fed through switches i i by circuits such as 55 connected in parallel on the main circuit 47.

The six contactors i i are mounted (FIG. 4) about the c am member 8 and angularly spaced by one sixth of the total rotational angle of the basket 1. They cooperate with the notch 9 formed in the periphery of the cam 8 along an accurate path corresponding to the sixth of the total rotational angle of the basket. Cam member 8 is keyed on the trunnion 6 such that when the basket is in its lowermost starting position (FIGS. 1 and 5), the movable member 56 of contact-or i falls into the forward end of notch 9 (seen in relation to the direction of rotation f, of the basket and of the cam '8). Thus, every successive precision rheostat R R is made operative, exclusive of all the others, as the basket 1 continues its tilting or rocking motion, the duration of operation of each rheostat corresponding to one sixth of the total tilt of the basket.

The basket 1 is thus theoretically divided into six portions or fractions x x (FIG. 4) having the same center-angle at about the axis XX. Each x thus corresponds to one sixth of the entire amount of liquid castiron in (FIG. 1) which has to be contained in the basket 1 to effect the casting of six pipes, each of which corresponds to one such slice.

On the main circuit 47 (FIG. 3) are connected in parallel six circuits such as 57 supplying signal lamps L through contactors 1' 1' which are in turn controlled by the cam 8. To this end, these contactors which are conected in the sam way as aforesaid contactors i, cooperate with a notch 9a formed in cam 8 and similar to notch 9. When the basket is in its lowermost starting position shown in FIGS. 1 and 4, the movable member 58 of contactor j falls into the forward end of the notch 9a.

It results from the foregoing arrangement that lamps L L can be lit in succession in the course of the rotational cycle of basket 1, signalling both the position of the basket and the particular rheostat which is operative at that time.

These lamps L L are preferably mounted on a control desk 59 (FIG. "1) adjacent the individual control wheels 69 controlling the operation of each rheostat R vFinally, the motorpump set P is fed through a two- .wire circuit 61, connected in parallel with the main cir- . cuit 47, 48.

A central switch is provided at 62 at the circuit inlet. The operation is as follows:

The basket 1 is assumed to be at rest (FIG. 1) and filled with cast-iron for the casting cycle; the first case which will be examined is that in which the number of pipes to be cast is equal to the number of rheostats R R i.e. the number of tilting fractions of the basket (=six in the chosen example).

When at rest, slides 27 of selector S and 27a of selector S are in their median position in which the basket is stationary (position of FIG. 1), and the slide 32 of the valve J is in its left-hand position for actuation of the pump P The slide 41 of the valve K is in its righthand position to close the pipe 40. The movable part of the centrifugally casting machine M is in its outermost right-hand position.

The jack 17 is fed, as known per se and accordingly not illustrated, to provide a leftward motion for the centrifugal machine towards the casting channel 11. At the very moment when this machine is started, slides 27 and 27a of selectors S and S respectively, are pushed by hand to the left and electric pumps P and P are supplied with pressure by closing the central switch 62. The electric circuit 61 of the impeller electric pump P is thus automatically closed. This is also true for the circuit 53 feeding the pouring pump P since at. rest the contactor C is closed while the associated contactor C is open. Pumps P and P are thus displaced and their output to the jack V is simultaneous and in parallel through respective pipes 26 and 31. The piston 23 of jack V lifts then rapidly the basket 1 until appearance of cast-iron at the casting spout 5. This is the impeller phase.

On the diagram of FIG. 5 where the tilt angles x are shown in ordinates and the times 2 as abscissae, the impeller stage is represented by the segment a -b As soon as cast-iron appears in the spout 5, the energized photocell 49 closes the contactor C thus energizing the solenoid E and displacing to the right the slide 32 of valve J to a position in which the pump P is inoperative. Since the output of this pump is now directed to the discharge, the pump P is the only one which continues to supply the pipe 26. The tilting of the basket 1 is nevertheless continuing but at a slower rate, Accordingly, after the impulsion which causes the cast-iron to overflow over the edge of the spout 5 and towards the weir 10, the melt flow into their weir, channel 11 and into the mold 13 at a predetermined speed which is a function of the output of pump P The movable portion M of the machine reaches its outermost left-hand position,'when the cast-iron is in the extreme right-hand end of channel 11 and starts receding to the right from this moment on. This is the pouring stage shown in FIG. 5 by the segment b -c and the difference of ordinates between the points b 0 corresponds to a tilt by angle x (FIG. 4), i.e. the first pouring fraction.

In the course of the displacement to the right of the movable part M of the centrifugal machine, the iron is cast over the entire length of the mold 13. A short time before the rightward travel of the part M is completed, slides 27 and 27a of selectors S and S respectively are manually pushed home to the right, thus setting the jack V to discharge. The basket 1 thus falls rapidly, bringing the melt level beneath the pouring spout and stop the casting, until such time as when the slides 27 and 27a of selectors S and S respectively are returned to their median stopping position. This is the back-tilt stage shown in FIG. 5 by the segment c d A pipe has thus been cast.

. During the stripping of the pipe, the machine is stopped and so is the basket 1. This stationary stage is shown by the horizontal segment ti -a in FIG. 5. It will be appreciated that when the level of the cast iron falls beneath the spout 5, at the start of the descent of the basket, the photocell 49 is no longer energized. The contactor C opens and slide 32 of valve J is automatically returned, under the action of spring-36, to the left to take a position in which impeller pump P can be operated.

Nevertheless the pump P remains inoperative since the slide 27a of selector S stops the oil pressure prior to its penetrating into the pipe 31a, first by interconnecting the discharge pipe 37 of pump P and the discharge pipe 30a, and by plugging thereafter the pipe 37.

When the centrifugal machine is operated again, the cycle is resumed through the successive stages: a [2 d and a (FIG. to cast the second pipe, and so on. It will be noted that the point b corresponds to a slightfuly larger ordinate than that of point 0 (end of the pouring step of the first pipe), since the impulse represented by the segment a b is specifically adapted to bring the melt to a level higher than the end 0 of the pour, so as to initiate the overflow in the spout 5 and thus the next casting step. This impulse is accordingly achieved by rotating the basket in the direction of arrow h by an angle exceeding the value represented by the ordinate difference of b and 0 which is the angle of rotation of the basket in the direction opposite to that of arrow h, to stop the pouring.

At the end of the last tilting x of the basket tilting cycle, following the stage c d of the basket return motion, while slides 27 and 27a of selectors S and S are held in their median inoperative position, the contactor C is manually closed. Slide 41 of valve K is then attracted to the left by the solenoid E thus opening the jack 23 to discharge through pipes 40 and 42. The piston of jack 23 completes its downward stroke returning the basket to its starting position for the first cast. This return stroke is shown in FIG. 5 by the segment d c Once the basket has fallen to its starting position (FIG. 1), the contactor C is opened.

The precision adjustment of the rotational speed of the basket during the pouring step is effected as follows: (FIGS. 3 and 4) At the start of the casting of the first pipe of a cycle, the contactor i is manually closed, thus closing the feed circuit 55 of relay r This relay opens the contactor I and renders operative the rheostat R Since the remaining contactors i i are open, the relays r r are not fed and the rheostats R R remain shorted by their respective shunts 54, and thus inoperative. At the same time, only the contactor j, is closed owing to the engagement of its movable member 58 into the notch 9a and only the lamp L is lit. This lamp accordingly signals the rheostat R which will have to be acted upon manually through the corresponding control wheel 60 (FIG. 1) to slightly modify from the next six-cast cycle on, the pouring speed corresponding to the first cast of each cycle and thus the flow rate of the cast-iron, in case the pipe cast in the first cycle is slightly too heavy or slightly too light.

Lamp L remains lit and rheostat R remains operative as long as contactors i and are engaged in the notches 9 and 9a, i.e. during the rotational fraction x of the basket or the pouring of the metal corresponding to the casting of the first pipe.

When the second tilting fraction x is initiated to cast the second pipe, contactors i and i are disengaged from notches 9 and 9a, while contactors i and 1' are engaged thereinto. The same cycle is repeated until the completion of the last tilting fraction x When basket 1 is empty at the end of its tilting motion, the contactor C is manually closed, thus causing the basket 1 to fall and the contactor C to open, the supply being accordingly cut to all the rheostats and to the pouring pump P Once the basket 1 has returned to its original position, contactor C is again manually opened, thus returning contactor C to its normal closing position, and accordingly actuating against the pouring pump P In the example under consideration, wherein six pipes are cast at each rotational cycle of the basket, if one of the cast pipes, e.g. the third pipe, is slightly underweight or slightly overweight whereas the preceding pipe was adequate, this implies the existence of some localized irregularity of the basket shape in the corresponding tilting fraction x lamp L which lights up sends a signal to warn that the corresponding rheostat R requires adjustment, and this rheostat will accordingly be acted upon to correct the rotational speed of the basket for this third tilting step and adjust the pouring output thereof. For the casting of the next pipe (angle x.;), the basket resumes automatically the speed it had before this last adjustment, as the rheostat R is by then shorted. But, in all the subsequent six-pipe cycles, the corrected adjustment of the rheostat R remains operative and enables each third pipe of a cycle to be produced with an absolutely accurate weight standard, irrespective of the surface fault in the portion of the basket corresponding to the third filting fraction x Now, the more common case will be examined, in which the number of pipes to be cast during one cycle does not correspond to the number of tilting fractions x ar of the basket rotational cycle but is lower then said second number. In this case, each tilting angle x x corresponds to a fraction of the weight of one pipe and accordingly the rheostat associated with this angle has influence only on said weight fraction of the pipe. Thus, for example, if only three pipes are to be cast per cycle, each rheostat will be operative only with respect of the half of each pipe. During the first casting cycle, two lamps L will be sequentially lit during the casting of the same pipe, indicating the two rheostats which will have to be acted upon, if necessary, for a subsequent adjustment of that same pipe during the next cycles.

It ensues from the foregoing that owing to the presence of the photo-cell 49 before the pouring spout 5, the appearance of molten metal at the spout 5, the appearance of molten metal at the spout gives the signal to initiate the pouring cycle. The operator can thus be certain that the actual initiation of the casting corresponds truly to the start of the pouring step from the rockable ladle.

Owing to the fractioned adjustment of the basket rotational speed, the molten metal output is constant and the operator can be certain that the amount of melt supplied to the mold will always be the same and that the obtained pipes will be accordingly of the correct weight and regular wall thickness.

In accordance with the alternative embodiment shown in FIG. 6, the notch 91: of the first illustrated example (FIG. 4) is replaced by a notch 9b offset to the rear (direction opposite to that of arrow i in relation to said notch 9a by an amount equal to half the centre angle x of a tilting fraction.

This results in the lighting of lamps L L instead of being simultaneous with the energization of rheostats R R being delayed in relation thereto. This embodiment is useful in the cases where the melt level at the end of every casting step is not accurately located at the theoretical limits between two successive fractions x x which are shown in dash-dotted lines in FIG. 6, but on the contrary along a pattern shown in mixed lines at XZ; intermediate two sequential theoretical limits, the tilt Z XZ corresponding to the necessary metal volume to cast one pipe. This occurs when the basket has a surface irregularity such that, at equal contents, the melt level is higher or lower than the normal level, or when a rest of molten metal is used, which does not fill the basket to the theoretical level. This last eventuality is illustrated in FIG. 6. Accordingly the basket is at the start in a tilted position in order to bring the metal level to the proximity of the pouring spout 5'. An impulse stage will thus be sufficient to cause the melt to overflow over the spout and initiate the casting. At the start of the casting of the first pipe which takes place approximately at the end of the second fraction x the com tactor i is engaged into the notch 9b. Lamp L is ac cordingly lit, showing that the second half of the second fraction has been by-passed and that, accordingly, said second fraction has but little influence on the weight of the pipe. The third fraction x is rapidly initiated, thus closing the contactor i energizing the rheostat R and deenergizing the rheostat R When the cast-metal corresponding to the first half of the fraction x has been poured, contactor i is disengaged from the notch 9b of cam 8, while the contact i is engaged thereinto. Lamp L lights up.

When the pouring corresponding to the fourth fraction x is started, rheostat R is substituted to rheostat R Lamp L remains lit until the metal corresponding to the first half of the fourth fraction is poured. At that time, the notch 9b causes the lamp L to become lit while lamp L, is extinguished. This lamp L remains lit until the end of the first pipe casting, since this pipe is completed after the pouring of the metal corresponding to the second half of the fourth fraction x and corresponds at a rotational point of cam 8 at which the notch 91; confronts the contactor j Owing to the lighting of lamps L and L after the initiation of the cast, the operator is aware that the third and fourth fraction x and x.; of pouring have influence on the major part of the weight of the first pipe, and that the rheostats R and R are the ones to be acted upon to modify the pouring speed, if the first pipe is too heavy or too light. Thus the lagging of the lighting of the lamps in relation to the energization of the corresponding rheostats, this lagging being equal to half of one fraction x of tilting the ladle oifers the advantage to enable the fractions to be distinguished: those where more than half has been poured and those Where less than half has b en poured, thus permitting a more accurate adjustment of the weight of the pipes, taking into account the fractions for which more than half of the metal has been poured.

It is to be understood that this invention is not confined to the described and illustrated embodiments which have been chosen merely by way of examples.

Thus, the invention which has been described in connection with a transliding-type of centrifugal machine, of the De Lavaud type can also be applied to machines having no transliding motion, such as a machine of the Arens type.

The basket tilting can also be divided in any desired number of fractions concentrically located in respect to the axis X-X, in accordance with the number of pipes to be cast in succession with a single filling of the basket, and also as a function of the desired precision in the pouring speed, which depends in turn on the allowed tolerances in the manufactured product weight.

Further, the slides 27 and 27a of the respective selectors S1 and S2 controlling the motion of the basket, can be automatically actuated by means known per se, as a function of the moving rate of the part M of the machine.

Finally, the lagging of the lamp lighting can be achieved by other known means, for example, by delaying relays.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a control device for a molten-metal pouring ladle of a centrifugal casting machine, said ladle which is provided with a pouring edge being tiltable about a fixed horizontal axis of rotation and thus permitting after being filled a plurality of sequential casting steps, in combination therewith: a hydraulic jack to tilt said feed ladle about said axis; an electric pouring pump and an electric impelling pump, said pumps discharging in parallel into said jack; a main supply circuit; two independent electric supply circuits for these electric pumps and connected with said main circuit; a photocell responsive to appearance of molten metal at the pouring edge of the ladle; means controlled by this cell to render the impeller electric pump inoperative as soon as the met-a1 makes its appearance at said pouring edge; a plurality of manually adjustable rheostats in the supply circuit of the pouring electric pump, these rheostats enabling the speed of said pouring electric pump to be individually and manually adjusted for a given fraction of the total tilting angle of the ladle; and a cam integrally rotatable with the ladle to individually and in succession render operative each of the rheostats for automatically adjusting, in the corresponding fraction, the driving speed of the pouring electric pump in accordance with the manual adjustment of said rheostat.

2. In a control device for a molten-metal pouring ladle of a centrifugal casting machine, said ladle which is provided with a pouring edge being tiltable about a fixed horizontal axis of rotation and thus permitting after being filled a plurality of sequential casting steps, in combination therewith: a hydraulic jack to tilt said feed ladle about said axis; an electric pouring pump and an electric impelling pump, said pumps discharging in parallel into said jack; a main electric supply circuit; two independent electric supply circuits for these electric pumps and connected with said main electric circuit; a photocell responsive to appearance of molten metal at the pouring edge of the ladle; means controlled by this cell to render the impeller electric pump inoperative as soon as the metal makes its appearance at said pouring edge; two pipes in parallel connecting said jack to both electric pumps and, respectively disposed on said pipes, a first selector having a movable member and, in series, a valve member forming said means controlled by the cell, and a second selector having a movable member, the movable members of said two selectors being interconnected and being movable between two positions, such that in one of said positions both pumps are simultaneously connected, namely; the impeller pump to said valv member and the pouring pump to said supply pipe, whereas in said other position, both pumps are connected to discharge; said valve member being so arranged and combined with the cell that, prior to the metal appearing at the pouring edge of the ladle, said valve establishes communication between the second selector and said supply pipe, and as soon as the metal appearance takes place at said pouring edge, said valve sets the second selector to discharge.

3. In a feeding device of a centrifugally casting machine, in combination therewith: a frame; on this frame two bearings defining a horizontal axis of rotation; a feed ladle having a pouring edge and a pair of trunnions rotated in these hearings, whereby said ladle can be rotated about said axis, said ladle having a capacity such that after being filled, said ladle permits by sequential partial pourings to effect a plurality of successive casting operations; and, to cause said ladle to be rocked, a control device comprising a hydraulic jack to tilt said feed ladle about the rotational axis thereof; an electric pouring pump and an electric impeller pump, said pumps discharging in parallel into said jack; a main electric supply circuit; two independent electric supply circuits for said electric pumps and connected with said main electric circuit; a photocell responsive to appearance of molten metal at the pouring edge of the ladle; means controlled by this cell to render the impeller electric pump inoperative as soon as the metal makes its appearance at said pouring edge; a plurality of manually adjustable rheostats in the supply circuit of the pouring electric pump, these rheostats enabling the speed of said electric pouring pump to be individually and manually adjusted for a given fraction of the total tilting angle of the ladle; and a cam integrally rotatable with the ladle to individually and in succession render operative each of the rheostats for automatically adjusting at will, in the corresponding fraction, the driving speed of the pouring electric pump in accordance with the manual adjustment of said rheostat.

4. Device as claimed in claim 3, wherein the tilting jack has connected therewith a supply circuit comprising two pipes in parallel connecting said jack, respectively,

spasm/e with the pouring electric pump and the impeller electric pump; and respectively disposed in said pipes, a first selector having a movable member and, in series, a valve member forming said means controlled by the cell, and a second selector having a movable member, the movable members of said two selectors being interconnected and being movable between two positions, such that in one of said positions both pumps are simultaneously connected, namely: the impeller pump to said valve member and the pouring pump to said supply, whereas in said other position, both pumps are connected to discharge; said valve member being so arranged and combined with the cell that prior to the metal appearing at the pouring edge of the ladle, said valve member establishes communication between the second selector and said supply pipe, and as soon as the metal appearance takes place at said pouring edge, said valve member sets the second selector to discharge.

5. Device as claimed in claim 3, wherein a contactor is seriesconnected in the electric supply circuit of the pouring pump with said adjusting rheostats, and wherein, for each rheostat, there is provided a short-circuiting circuit having a short-circuiting switch mounted therein and, for controlling said short-eircuiting circuit by said cam, an electro-magnetic relay having an energizing circuit which is connected with the electric supply circuit and includes a control switch acted upon by said cam.

6. Device as claimed in claim 5, wherein there is provided for each rheostat, a signalling lamp whose supply circuit is connected with the main electric supply circuit and comprises a switch combined with the cam, said switch being adapted to be closed by said cam as a function of the closing of the control switch of the electromagnetic-relay circuit controlling the short-circuiting switch of said rheostat.

7. Device as claimed in claim 6, wherein the control switches of the rheostats and lamps, combined with the cam, are so located about said cam that each lamp is synchronously fed with the energizing of the corresponding rheostat.

8. Device as claimed in claim 6, wherein the control switches of the rheostats and lamps, combined with the cam, are so located about said cam that each lamp is fed With a certain lag with respect of the energizing of the corresponding rheostat.

References Qited in the file of this patent UNITED STATES PATENTS 2,768,413 AleX-anderson Oct. 30, 1956 FOREIGN PATENTS 679,075 Great Britain Sept. 10, 1952 294,768 Switzerland Nov. 30, 1953

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