FR2459699A1 - MOLTEN METAL LOADER FOR SHELL CUTTING MACHINE - Google Patents

Abstract

THE INVENTION RELATES TO A MOLTEN METAL FEEDER INCLUDING A COLLECTOR POCKET THAT CAN ROTATE AROUND A HORIZONTAL AXIS 18 UNDER THE EFFECT OF A MOTOR 35 BETWEEN A HORIZONTAL POSITION AND AT LEAST AN INCLINED POSITION, TO TAKE THE METAL AND POUR IT INTO THE MACHINE FILLING HOLE 6. THANKS TO A REGULATOR, TILLING IS CARRIED OUT IN THREE PHASES: THE METAL APPROACH, THE DISTRIBUTION NOZZLE 24, AT A FIRST SPEED, A START OF TILLING AT A SPEED LOWER THAN THE FIRST, AND AN END OF TILLING ACCELERATED UNTIL AT A HIGHER SPEED THAN THE FIRST. THE INVENTION APPLIES TO SHELL CASTING MACHINES.

Description

The invention relates to a molten metal magazine for

casting machine in shells.

  Melt loaders are already known for press casting machines which periodically transfer suitable amounts of molten metal,

  melting furnace at the mouth of the mold.

  It is also known that a shell casting machine is a machine for forming metal bodies in which the molten metal, taken from a melting furnace, is poured into

  a hole that communicates with the inner cavity of the mold.

  The often small dimensions of this hole require special methods of pouring that prevent the use of known loaders for molding presses.

  the loading of casting machines into shells.

  The object of the invention is to provide a charger which,

  while retaining practically the structural characteristics

  In addition, the known loaders for presses for casting under pressure have special characteristics which make it perfectly suitable for feeding a shell casting machine. According to the invention, this object is achieved by means of a magazine comprising a molten metal collecting bag articulated so as to be rotatable about a horizontal axis and motor means designed to control the rotation of the pocket between a horizontal position of at least one inclined position for withdrawing the metal from the furnace and pouring it into the filling hole of the machine, characterized in that the motor means is accompanied by a speed regulator designed to control the rotation from the pocket, from the horizontal position to the inclined position, for the pouring of the metal into the hole of the machine according to three successive phases at different speeds, a first phase comprising a first rotational speed making it possible to approach the metal of a nozzle of distribution of the pocket, - 2 - a second phase comprising at least a second speed of rotation lower than the first, allowing to pour the most of the molten metal and the third phase having a progressive acceleration towards a third speed of rotation, greater than the first,

  to pour the residual portion of the molten metal.

  In other words, in the metal loader according to the invention, a suitable speed regulator makes the pocket turn substantially in the same way

  it should be manually turned

  kill a quick pouring but without bottlenecks, overflows etc ... By cons, the rest of the charger and in particular

  its mechanical structure, can remain entirely identi-

  to the corresponding part of the chargers known for

presses for casting under pressure.

  An example of a practical embodiment of the charger according to the invention is shown more clearly in the accompanying drawings, in which: FIGS. 1 and 2 show schematically, in elevation and in plan, the general constitution of a charger according to the invention serving transferring molten metal from a melting furnace to a shell casting machine; Figure 3 is a detailed view in partial section of a portion of the loader shown in Figure 1 and partly in section; Figure 4 is a horizontal section along the line IV-IV of Figure 3; FIG. 5 shows the upper part and the lower part of the magazine, in axial section deviated from 90 with respect to FIG. 3; Fig. 6 shows said upper and lower parts of the magazine in axial section deviated by 1800 in relation to Fig. 3; FIG. 7 shows the top of the magazine in section along the line VII-VII of FIG. 6; FIG. 8 is a block diagram of the speed regulator which determines the three-phase rotation of the collecting bag; of molten metal which is part of the charger represented by the preceding figures: FIG. 9 is a graph illustrating the variation imposed on the speed of rotation of the pocket during the

pouring phases of the molten metal.

  FIGS. 1 and 2 show a magazine 1 associated with a melting furnace 5 equipped with a sampling mouth 4 and with a shell casting machine 7 equipped with a filling hole 6. The machine 7 comprises, in a known manner, a fixed base 8 on which are arranged so

  mobile two plates 10 controlled by hydraulic cylinders

  The plates 10 respectively support half-molds 11 which together form a mold having a molding cavity 12 accessible through the filling hole 6. Inside the mold cavity 12

  is housed a core 13 of appropriate form.

  The loader 1 comprises in the first place a gantry frame 2 disposed astride the melting furnace 5 and the shell casting machine 7. A reciprocating carriage 14 is carried and guided by a pair of horizontal bars 3 constituting, with a posterior casing 15, the crossmember

  horizontal of the frame in portico. Appropriate motor means

  required and in themselves known to ensure the

  alternate carriage 14 along the guides 3.

  As can be seen better in FIGS. 3 and 4, the carriage 14 supports two coaxial vertical bars 16 and 17 whose first door at the lower end has a stirrup 30 to which is articulated at 18 (FIGS. sampling and pouring 19 provided with a distributor nozzle 24 (Figure 5) while the second bar is connected by its lower end, by a rod 20, provided with end journals 21 and 22, a bead

  longitudinal 23 of the pocket 19 (Figures 3, 5 and 6).

  The outer vertical bar 16 is supported by the carriage 14 so as to slide axially (through a guide 29) and comprises, for its movement, as shown in Figures 3 and 4, a rack portion 25 meshing with a pinion 26 mounted on the output shaft 28 of a variable speed motor unit 27. The inner vertical bar 17 is in turn housed so as to slide axially inside the bar 16 and its upper end is fixed (Figure 5) to an upper extension 31 provided with a rack portion 32. As shown in Figures 6 and 7, the latter meshes with a pinion 33 mounted on the output shaft 34 of a motor at a speed variable 35

  mounted on the top of the outer bar 16.

  The charger described with reference to Figures 1 to 7 is intended to operate as follows. After sliding the carriage 14 along the guides 3 to bring the pocket 19 in the position substantially superimposed on the mouth 4 of the oven 5 (Figure 1), the drive unit 27 is actuated so as to lower the two bars coaxial

  16 and 17, until the pocket 19 is inserted into the oven 5.

  At this stage, the motor unit 27 is stopped and the drive unit 35 is actuated causing the lowering of the inner bar 17, 31 relative to the outer bar 16, the pocket 19 rotating around the pin 18 and the inclines so that its beak 24 is turned upwards: the pocket 19 can thus be filled with the molten metal contained in the furnace 5. The motor unit 35 is then actuated in reverse order so as to return the pocket 19 to a horizontal position and then the motor unit 27 is also actuated in the opposite direction in such a way as to raise the two coaxial bars 16 and 17, 31 and thus the pocket 19 together again. The carriage 14 is then moved along the guides 3 to bring the pocket 19 above the filling hole 6 of the machine 7, after which, on the average of the motor unit 27, the pocket 19 is lowered to the

  hole 6 of the shell casting machine.

  Until this moment, all the movements of the various organs of the loader were running at a constant speed, succeeding each other automatically under the intervention

  various end-of-stroke devices such as micro-

  switches 36, 37 and 38, Figure 3, with which cooperate respective cams 39, 40 and 41. However, once the pocket 19 has been approached the hole 6 of the casting machine and the time has come to controlling the rotation of the ladle to pour the molten metal it contains, a speed regulator assistant to the power unit

  in action, this regulator being able to subdivide

  the three-stage pouring operation distinguishing

  by different speeds of rotation of the pocket.

  An example of such a speed regulator is shown schematically in FIG. 8 and comprises first of all a pulse generator 42 associated with the output shaft 34 of the motor 35 so as to emit a pulse for each angle of rotation. predetermined of the shaft 34; this pulse generator may be formed for example of a toothed wheel mounted rigidly on the shaft 34 and a fixed sensor, for example of the electromagnetic type, capable of detecting the passage of the teeth of said wheel. The pulse generator 42 supplies two pulse counters 43 and 44, calibrated so as to respectively control the opening and closing of corresponding contacts 45 and 46 after the counting of different numbers of pulses N1 and N2 (N1 <N2 ) corresponding to respective rotation angles S1 and S2 of the pocket 19. These contacts 45 and 46 control respective potentiometers 47 and 48 set at different levels P1 and P2 (P1> P2) and to which is added a third potentiometer 49 set at a level P3> P1. The potentiometers 47 and 49 directly, and the potentiometer 48 via a ramp generator 50, connect a positive terminal 51 to a first input of a differential amplifier 52.

  equipped with a second input connected to the ground via

  A second differential amplifier 54 in turn comprises a first input connected to the output of the amplifier 52 and a second input connected to ground via a variable reference resistor 55. Finally, it is a role of a pulse former 56 to transform the available DC voltage at the output of the amplifier 54 into a succession of pulses at a constant frequency and of variable duration depending on the value of said voltage. These pulses provide control of a SCR diode bridge rectifier 57, interposed between the motor 35 (DC type) and an AC power supply 58, delaying the timing of the SCR diode initiation.

  when the pulse duration decreases and vice versa.

  The speed regulator of FIG. 8 ensures that pouring of the molten metal from the cup 19 into the hole 6 of the casting machine takes place in three phases.

  successive graphs shown in Figure 9.

  Once the engine 35 has been started

  With the aid of a command from an appropriate device responsive to the completion of the descent stroke of the pocket 19, the motor controls, by raising the bar 17, 31, the progressive rotation of the pocket 19 (in the desired direction to tilt the spout 24 downwards), at a constant speed V1 fixed by the potentiometer 47 - (- the current does not pass, in this case, by the potentiometer 49 set to a higher value); this makes it possible to perform the first part of the rotation stroke of the pocket, more precisely that which is necessary to bring the metal close to the dispensing spout 24, at a fairly steady speed

  and therefore without wasting unnecessary time.

  Meanwhile, the two pulse counters 43 and 44 counted the pulses as they were emitted by the generator 42 with a frequency dependent on the speed of rotation of the pocket. When the counter 43 has arrived to count the number N1 fixed in advance, corresponding to a rotation of the pocket equal to S (FIG. 9), the counter 43 causes the opening of the contact 45 so that, this time, is the larger value potentiometer 49 which sends to the first input of the amplifier 52 a smaller control voltage which, in turn, through the amplifiers 52 and 54 and the trainer pulses 56, gives rise to pulses of reduced duration which, by delaying the ignition of the SCR diodes of the bridge rectifier 57, reduce the supply of the motor 35 and therefore its speed. The rotational speed of the pocket 19 thus falls to a reduced value V2. fixed as said by the potentiometer 49, so as to pour the molten metal of the ladle into the filling hole of the casting machine, with a sufficiently small speed to avoid clogging, overflows and other disadvantages of this kind. If desired, the speed V2, instead of remaining constant, may vary between several neighboring values, each change in speed being determined by the intervention of a respective additional pulse counter which controls a respective potentiometer such as but obviously

different value).

  However, when the counter 44 has arrived at counting the number of pulses N2 fixed in advance, corresponding to a rotation of the pocket equal to S2 (FIG. 9), S1 being chosen so that at this stage the major part molten metal has left the pocket 19, the counter 44 controls the closing of the contact 46 so that the potentiometer 48 (of lesser value) is substituted for the potentiometer 49 (of greater value) in the supply of the amplifier 52. However, the ramp generator 50 ensures that the input voltage of the amplifier 52 does not immediately reach the value corresponding to the calibration of the potentiometer 48 but increases in linear function up to this value. following a ramp of predetermined slope. The same is true, of course, of the output voltage of the amplifiers 52 and 54, the duration of the output pulses of the pulse former 56, the power supply of the motor 35 and, finally, the speed of rotation of the the pocket 19 which, as shown in FIG. 9, increases linearly up to a maximum value V3. The pouring operation of the molten metal is thus completed by a last phase of rotation at an increased speed which quickly allows the final evacuation to take place.

the metal of the pocket 19.

  A suitable limit switch finally detects the fact that the maximum angle of rotation S3 is reached and starts the return cycle of the loader, that is to say it controls the motor 35 so as to bring the horizontal pocket, after which the motor 27 returns the pocket to a higher position and the carriage 14 is returned to the initial position above

of the melting furnace.

  If desired, the same loader can be assigned to the loading of several machines to cast in shells, arranged on both sides of the same oven or all in a circle around the oven. In the latter case, obviously, the frame of the charger will have to be able to turn to place successively straddling the various machines

to sink in shells.

- 9 -

Claims (5)

  1. A molten metal charger for shell casting machine, comprising a molten metal collecting bag 19, rotatably articulated about a horizontal axis 18 and motor means 35 designed to control the rotation of the pocket 19 between a horizontal position of rest and at least one inclined position making it possible to take the metal in the furnace and pour it into the filling hole 6 of the machine, loader characterized in that the motor means 35 is associated with a regulator of speed designed to control the rotation of the pocket 19, from the horizontal position to the inclined position, for the pouring of the metal into the hole 6 of the machine in three successive phases at a different speed, a first phase comprising a first rotational speed allowing to approach the metal of a beak   distribution 24 of pocket 19, a second phase   at least a second rotational speed lower than the first, to slowly pour most of the molten metal and the third phase with a gradual acceleration to a third speed of rotation, greater than the first, to pour   the residual part of the molten metal.   2. A charger according to claim 1, characterized in that the motor means 35 comprise an electric motor 27 and the speed controller comprises a pulse generator 42 designed to emit a pulse for each rotation angle fixed to the forward of the pocket and at least two pulse counters 43, 44 arranged to provide respective commands when respective numbers set in advance are reached, these commands acting on the power supply of the motor 27 so that a first command transmitted by a first counter 43 when a first number fixed in advance is reached causes the immediate transition from the first to the second speed and a second command issued - 10 -   by the second counter 44 when a second number fixed in advance and greater than the first is reached causes the progressive acceleration of the motor 27 to the third speed. 3. Charger according to claim 2, characterized in that the first command acts on the input voltage of an amplifier 52 so as to switch from a first value to a second value less than the first and that the second command acts on the input voltage so as to switch it, with a ramp rate, from the second value to a third value higher than the first.   4. Charger according to claim 3, characterized in that the voltage values mentioned are fixed by respective potentiometers 47, 48 selectable, placed at the input of the amplifier 52 and the potentiometer 48 relative to the third voltage value is associated with a ramp generator 50 designed to respond to the selection of the potentiometer 48 by a progressive increase in voltage to the third value.   5.- Charger according to one of claims 3 and 4,   characterized in that the amplifier 52 supplies a pulse generator 56 of variable duration for the control of a bridge rectifier 58 with SCR diodes interposed between the electric motor 35 of the direct current type   and AC power supply 58.