INTERCHANGEABLE DEVICE FOR AXIALLY MOVING THE STOPPER OF A TUNDISH

Abstract: The invention concerns a commutable device for regulating the stopper (47) of a ladle (60), whereby the stopper (47) immersed in the ladle (60) is connected to a shaft (50) which moves in a direction axial to the stopper (47) itself and which comprises advantageously a tract (58) cooperating with axial drive means (57), said device including in mutual cooperation and coordination: - an actuator means (14) cooperating with said axial drive means (57), whereby intermediate safety means are advantage­ ously present, - and means to control and regulate the actuator means (14).

Description: Description of the invention entitled: "Commutable device for regulating the stopper of a ladle" in the name of CEDA S.p.A. at Buttrio -Submitted on under No. This invention concerns a commutable device for regul-. casting the stopper of a ladle. To be more specific, the invention concerns a device able to impart and regulate an axial motion in the stopper as to govern the flow of the casting of molten metal through the outlet of a ladle. In particular, the invention in question envisages the. embodiment of a device which can be commuted depending on the source of energy used, so as to employ electromechanical -and/or on mechanical means belonging to said device. It is known that in continuous casting plants the reg-. ulation of the flow of the casting of molten metal from the. .ladle into an appropriate ingot mould is brought about by -varying the aperture of tile discharge outlet of the ladle. - In practice this operation is generally carried out by .using a stopper which is immersed in the molten metal in the ladle and positioned above the outlet. Variation oX tile outgoing flow is brott about by novr ing said stopper axially. If tl.e operation to fill the ingot mould is to be carried out properly, it is important that the displacement of the stopper should be very accurately controlled. This is necessary to revent even sall variat- ions in the flow from leading to variations in the volume - of molten metal in the ingot mould. Said variations cause grave risks of a possible over- flow of said molten metal and of a defective quality in the finished product. It is also necessary to bear in mind the fact that the personnel engaged in the continuous casting process carry - out regulation of the stopper at a sale distance from the casting flow and ingot mould, and this does not permit a good visual control of the level of molten metal. For these reasons the displacement of the ladle stop- per in the known art is obtained very often with operations which.are not manual; in fact, hydraulic actuators are wide- ly employed but, on the other hzzd, involve considerable - risks and shortcomings. Above all there exists the noteworthy danger due to the presence of the highly inflammable oil used in the hydraulic equipment under high pressure. There is also the drawback that it is necessary to use pipes to convey the oil which are bulky and deteriorate readily, particularly in surroundings where incandescent - materials are being cast. The properties of the oil itself, which undergoes considerable changes in temperature, may be altered and tilere- by modify the response o the hydraulic actuator itself. The invention in question, therefore, proposes to em- body a device to regulate the temporary position of the ladle stopper in a very a@curate manner, said device being able to cooperate, by means of its mechanical part, with a rod or axial structure substantially parallel to the stopper so as to govern the movements of the stopper itself. The device is extremely safe or indeed is free from risks and is affected to a negligible extent by creep due to changes in temperature. moreover, the invention enables a fully automated regulating device to be obtained. In fact, one or more signals can be derived from a - suitable transducer device able to measure the level of the molten metal in the ingot mould, and said signals can be e ployed to govern the device in question for regulating the stopper. In substance it is the level itself of the molten metal in the ingot mould which governs the movement of the stopper for opening or closing the outlet of the ladle. The invention, therefore, consists of a commutable de- vice to regulate the stopper of a ladle, whereby the stop- per immersed in the ladle is connected to a rod which moves axially in respect of the stopper itself and which comprises advantageously a tract cooperating vrith axial drive means, said device being characterized by including in nstual cooperation and coordination: - an actuator means cooperating with said axial drive means, intermediate safety means being advantageously present, - and means to control and regulate the actuator means. We give hereinafter, as a non-restrictive example,the description of a preferential embodiment of the invention, at the same time referring to the attached tables, wherein- Fig. I shows diagrammatically a regulating circuit and a system for activab the ladle stopper; Fig. 2 short diagrammatically a variant of the regulating - circuit of Fig. I; Fig. 3 shows an example of the application of the actuator system to a ladle stopper; Fig. 4 shoves ç viev, of an actuator system in orthographic projection; Fig. 5 show a plan view in orthographic projection of the - - actuator system of Fig. 4 partially cut away; - Fig. 6 shows diagrammatically a structural variant for ap- plication of the actuator system Fig. 7 shows diagrammatically a variant of the manual oper action of Fig. 6; ; Fig. 8 shows diagrammatically a further structural variant for application of the actuator system; Fig. 9 shows diagrammatically a variant of the manual operation of Fig. 8. In the Figures the same parts of parts performing the same functions bear the same reference numbers. Fig. I show diagrammatically the connections between - the regulating and actuating elements comprised in the de-- vice in question. In the example given the signal IO indicating the level II is picked up by a transducer I2 of any desired type - and is conformed and sent in the form of a signal 15 of a - suitable nature to an absolute comparator 16. Said compara- - tor I6 controls the level II of the molten material in the ingot mould I7. The comparator I6 is placed within the means I3 con- - trolling and regulating the speed of the actuator I4, which in our example is of an electromechanical type. The signal 10 is also sent to a summation means I8. In n the absolute comparator 16 are preset, by means of suitable regulators 19 and 20, values of maximum and minimum thres hold corresponding to the maximum and miniraum values respect . ively of the level II in the ingot mould 17. - If the level II surpasses the margin established with the values of maximum and minimum threshold, this fact is - indicated by suitable luminous or optical signaling means 21 and 22 or by suitable analogue or digital indicator in struments. The signal I5 is added algebraically in the summation means I8 to a comparison signal 23 which is of the same phy sical nature as the signal 15 and which corresponds to the value of the optimal level II and is sent by a suitable ad justable 25 generator 24. The error signal 26 obtained from the algebraic sum of the signals 15 and 23 is compared in a comparator 27. In the comparator 27 the margin of the variations in - level II, as permitted in good working practice, is preset with a threshold of a positive value and a threshold of - a negative value by means of two regulators 28 and 29. Suitable signalling means 30, 31 and 32 indicate either the surpassing of the value of the one or the other of said thresholds by the error signal 26 or else a condition of optimal level II determined by the presence of said level - II within the field of values enclosed between said thres holds. The error signal 26 is also sent to a regulation sys- - tem 33 which comprises two regulating groups 34 and 36 suit ably controlled (38-39-40-4I a1d 42-43-44-45), a summation means 35, a position transducer 37 and a converter 48. In particular, the error signal 26 is sent to a regul- ating group PID 34 having a proportional, integrating and - derivative action. The respective factors of proportionality, integration ,and aerivation and the initial value of integration of said group PID 34 are preset and governed by meals of suitable - regulators 38, 40 and 41. To lessen the inertia of the response of the regulation system to variations in level II, within the summation means 35 there is carried out an algebraic addition of the signal of position 46 of the stopper 47 (asconing frown the regul-- ation group PID 34) to the signal of retroaction49 of pos action of the stopper 47. Said signal of retroaction 49 of position of the stops per 47 is obtained by monitoring the movements of the rod - 50 by means of the position transducer 37. A converter 48 processes the signals coming from the position transducer 37 and emits the retroaction signal 49 conformed in such a way that it can be compared with the signal of position 46 of the stopper 47. The summation means 35 sends a position error signal 51 to the regulating group PID 36, where the regulaticn - parameters are controlled by means of the regulators 42, 43, 44 and 45. The signal 52 emitted by the regulating group 36 is amplified by an amplifier 53 and is used thereafter to re- - gulate the speed of the actuator I4 or the position of the - stopper 47. In particular, regulation of the speed of the actuator I4 can be done continuously or step-by-step or in a proport - ional manner. A clutch 54, which can be operated by hand with means - 55 that are rod means in our example, enables the shaft 56 of the actuator I4 to be connected to the drive means 57. Said axial drive means, which are conformed --;ith a toothed sector 57 in our example, are meshed with a suitable . equipped tract 58, which in the present example is conformed rack-wise and is present on the shaft or axial structure 50 - able to cooperate with the closure stopper 47 of the outlet hole 59 of the ladle 60. The toothed sector 57 can also be operated by hand - with a suitably placed rod 61. In particular, operation by hand is usually carried out after the toothed vector 57 has been disconnected froc the shaft 56 of the actuator I4 by means of the clutch 54. In actual fact the clutch 54 acts also as a means to limit torque for the actuator I4. Said clutch allows its parts to be released from each other whenever, owing to accidental causes, the electro - - mechanical actuator I4 forces the stopper 47 against an obstacle. In such a case' it is possible to act by hand on the shaft 50 in an emergency so as to bring the stopper 47 back to its released position without disengaging the clutch 54 beforehand. In this way overheating and possible burning of the windings of the electromechanical actuator 14 are avoided. An "ON-OFF" transducer 62 monitors the condition of the clutch 54 and signals by means of an appropriate indic-- actor (or signalling'me ns) 63 the connection of the actuator . 14 to the toothed sector 57. Purthermore, the transducer 62 governs the disconnect ion of the activator I4 from the regulating group PID 36 and the restoring of electrical conditions of starting the regulation in both the regulating groups 34 - 36. This governing takes place when the actuator I4 is disconnected from the toothed sector 57 by means of the clutch 54. The variant shown in Fig. 2 and indicated there with - the reference number I33 enables the structure of the re- - regulating circuit 33 of Fig. I to be sirplified. In particular, the regulating circuit 33 is employed advantageously with actuators which have a very quick res- ponse in tine, and its performance is excessive if used with slow actuators. In the specific example shove, it is enough to carry - out regulation vjith one single group PD 64 having a pro- . portional and derlvative action, since the actuator employed, being of an electromechanical type in this case, normally has a very slow response in tire. In the example of Fig. 2 the error signal 26 coming from the summation means I8 enters the group PD 64 employed to regulate the speed of the actuator I4 or the position of the stopper 47. . The factors or parameters of proportionality and deriv ration used in the regulation are preset and controlled by - means of suitable regulators 65 and 66. - The descriptions and considerations set forth in the case of the description of the example of Fig. I are also applicable to the remaining part of the control and regula--- tion means 13. Fig. 3 gives an example of the application of the act motor system 67 to the ladle 60 stopper 47. The actuator system 67, which is suitably anchored to a a supporting structure 68, comprises the toothed sector 57; - which in the examples of Figs. I, 2, 3, 4 and 5 is connected axially 56 to the actuator I4 and to the clutch 54 having a mechanical coupling and is connected radially to the hand- operated rod 6I by fork means 73. The toothed sector 57 cooperates with the tract provided with a rack 58 on the shaft having an axial structure 50. For illustrative simplicity said Fig. 3 does not show the clutch 54, which is shown instead in Fig. 4 and 5. The shaft 50 is anchored substantially parallel to the stopper 47 with a rigid arm 69 and is guided at its upper - end by a bush 70 upheld by the plate 71 screwed to the ladle 60. The stopper 47 is clamped to the rigid arm 69 inside a lateral regulation slot 72. The fork 73 is connected to the toothed sector 57 with a a bolt 74 and nut which permit n given sideways angulation of the rod 61 so as to facilitate the work of the machine operator. The fork 73 is connected to the rod 61 with a locking pin 75 so as to make replacement easy. In cooperation with the tract having a rack 58 there is envisaged on the plate 71 a reaction block 76, which can be replaced and is employed to prevent bending of the shaft 50 and to maintain good mechanical connection between the rack 58 and toothed sector 57 so as to improve their manoeuvrability and working life. The reaction block 76 includes an upper layer made of wear-resistant material; said material can be of a plastic type, for instance, of the type commercially knovin under the name of Rulon-LD. The shaft 50 slides with its lower part in a movable sleeve 77, which is guided axially by a support 78 and guide 79 which are solidly fixed to the plate 71. The movable sleeve 77 includes an elastic clamping half-ring 80, which makes it solidly fixed to the shaft 50; and a threaded tract 8I cooperating with a threaded ring 82 that can be revolved by means of the handwheel 83. By acting on the handwheel 83 circumferentially, the - threaded ring 82 is caused to revolve and displaces axially the sleeve 77 and the shaft 50 solidly fixed thereto. The rotation of the handwheel 83 leads to micrometric displacements of the shaft 50 and thereby to a fine adjust- ment of the course of the ladle 60 stopper 47. In substance, regulation of the ladle 60 stopper 47 by hand is normally carried by acting vdth the rod 6I on the toothed sector 57, while it is also possible to position the ladle 60 stopper 47 with micrometric movements by means of the handwheel 83. ghe tipper part of the shaft 50 is protected by meons of bellows 84 and an insulated enclosing screen-85. By means of its weight the shaft 50 enables the whole mechanical structure of the actuator system 67 to be loaded or pre-loaded so as to eliminate mechanical play which could be created in said structure owing to the stresses which it undergoes during working. This is done so as to prevent mechanical play, even of a small entity, from being able to interfere with the movements, sometimes only millimetric, of the stopper 47. - The actuator system 67 shown in Figs. 4 and 5 can be - readily put in a working position or withdrawn from said position; in the example shove it is equipped with pins 86 positioned above it and with two engagement devices 88. The pins 86 are suitable for being lodged in two ap- - propriate containing seatings 87 machined in the supporting structure 68 placed near the shaft 50, while the two en - - gagement devices 88 can be inserted into the engagement seatings 89 so as to clamp the whole actuator system 67. Fig. 5 shows the elements constituting the actuator I41 clutch 54 and toothed sector 57. In particular, the act uator I4 comprises a motor 90 the rotation of which is transmitted to a toothed wheel 91 by known means. The magnitude of the output of the actuator I4 is re- presented by the angular speed of the shaft 56 to which the toothed wheel 91 is keyed. The motor 90 employed in the actuator I4 is fed with - low tension so as to obviate the risks caused by the presence of high tensions. In our example a geared motor or step motor fed vith - direct current can be employed adventageously. . The toothed sector 57, the shaft 92 of which is coaxial - with the shaft 56 of the actuator 14, is solidly fixed with a a coupling pin 93 to the outer housing 94 of the clutch 5i..- The hub 95 of the clutch 54 is solidly fixed to the shaft 56. To make the toothed sector 57 and actuator 14 solidly fixed together, it is necessary to revolve the rod means 55 of the clutch 54. A torsional pin 96 which is engaged with the means 55. by means of a clamping knob 97 is able to rotate a fork means 98 cooperating with a grooved ring (drum) 99. Said grooved ring (drum) 99 is conformed outwardly in such a way as to be able to operate a suitably hinged IOI - lever 100 between two extreme stable positions correspond-- ing with the engagement or disengagement of the clutch 54 - when said ring 99 is displaced by rotation of the fork means 98. In the engaged position the lever 100 compresses the - clutch plates 1o2 - 1o3 and clamps them together and there by compresses the outer housing 94 against the hub 95,there by connecting the motor 90 to the toothed sector 57. When the motor 90 is disengaged from the toothed sect or 57, it is possible to rotate the latter 57. only by hand by means of a rod 61 lodged in an appropriate seating I04 and clamped therein with a screw element 105. Two frames 106 and I07 able to support and hold the actuator 14 and clutch 54 respectively are solidly fixed together with suitable cornecting elements 108 which sur - mount the toothed sector 57 and remain separate therefrom. There are comprised in the actuator system 67 some bea- rings 109 positioned between the frame I06 of the actuator . 14 and the toothed sector 57; said bearings enable said toothed sector 57 to rotate freely in respect of the frames 106 and 107. Other bearings IIO positioned between the shaft 56 of the actuator I4 and the toothed sector 57, together with the aforesaid bearings 109, enable said toothed sector 57 to rotate freely in respect of the shaft 56 when the actuator 14 is disengaged. Some variants to the embodiment of the invention are - possible. Thus in a first variant shown diagrammatically in Fig. 6 the actuator I4 can be connected axially through the clu- tch 54 to a toothed wheel III. Said toothed wheel III is positioned axially parellel to a toothed wheel 113 in such a way as to cooperate therewith 113. The toothed wheel III, however, can be positioned di versely and be inclined diversely in respect of the wheel - 113 by using transmission means and supplementary toothed wheels. The toothed wheel 113 is axially solidly fixed to a toothed wheel 114 so as to constitute axial drive means 112. Said axial drive means 112 comprise axially a threaded cyl- indrical through hole 115 cooperating with a circumferent- ially threaded tract 58 of the shaft 50. By engaging the actuator I4 with the toothed wheel III through the clutch 54, it is possible to revolve the axial drive means II2, which in turn impart a vertical movement to the shaft 50. The relative vertical movement as between the axial drive means 112 and the shaft 50 takes place because they are engaged separately from each other. In particular, the shaft 50 can'be engaged with some guide blocks 116 cooperating with lengthwise flat guide tracts 117 present in the upper and/or lower part of the shaft 50. Said guide blocks 116 enable the shaft 50 to move vertically and prevent it from rotating. The axial drive means 112 can be fixed and contained in a frame wherein the actuator 14, clutch 54 and toothed wheel 112 can also be lodged. The regulation of the shaft 50 by hand is brought about by rotating with the rod 6I a toothed sector 57 cooperating at right angles with the toothed wheel 114 of the axial drive means 112. It is possible to position the toothed sector 57 and toothed wheel 113 differently and incline them differently - in respect of each other by visualizing the employment of different profiles for the cooperating screw threads. Thus, for example, it is possible to make the toothed sector 57 and toothed wheel 114 coplanar. It is possible to * make the toothed sector 57 and toothed wheel 113 coplanar by eliminating the toothed wheel 114. A further regulation by hand can be carried out with suitable means 118 present in the lower part of the axial - drive means 112. A A different structuring of the manual activation can - be envisaged, as shown in Fig. 7. In particular, a toothed wheel 119 can be envisaged as being solidly fixed to the toothed wheel III. Said toothed wheel 119 cooperates with a toothed wheel I20 positioned at right angles to itself 119. The toothed wheel I20 can be operated by hand with - crank means I2I able to adhere at least partially to the outer flat side I22 of the said wheel I20 during said oper- - action. In particular, said crank means I2I comprise pins 123 able to be engaged in suitable seatings 124 machined in the outer flat side I23 of the toothed wheel I20 in such a way as to make the crank means 121 and toothed wheel 120 firmly fixed together during rotation by hand. Disengagement of the crank means I2I from the toothed wheel I20 is ensured with elastic axial repelling means 125 cooperating with a catch 126. It is possible to visualize the employment of different means to rotate the toothed wheel 120. It is possible to position the toothed wheels 119 and 120 differently and incline them differently in respect of - each other by using once again the connection of the actuator I4 and clutch 54 as shown in Figs. 6 and 7. It is possible to position and incline the actuator I4 in different ways in respect of the shaft 50, and transmission means and supplementary toothed wheels can be employed for this purpose. According to another variant of the embodiment of the - invention shown in Fig. 8, the actuator I4 and clutch 54 are positioned on the same axis as the shaft 50, an actuator I4 of a linear type being employed in this case. Vertical displacement of the shaft 50 takes place as an effect of the rotation of the inwardly threaded axial drive means 112 cooperating axially with said shaft 50. . The axial drive means 112 can be connected to the act uator 14 through the clutch 54 so as to be operated thereby I4. Vertical displacement of the shaft 50 accompanied by - the guide block 116 takes place in the way described for Fig. 6. Rotation by hand of the axial drive means 112 to cause vertical displacement of the shaft 50 can be brought about - by acting on the toothed sector 57 meshed with the toothed - - wheel 113 belonging to said axial drive means 112. - Said rotation by hand can also take place by acting - with the means connected to the rotor of the actuator 14 after the axial drive means 112 have been connecetd to the actuator 14 by the clutch 54. It is possible to foresee solutions through cooperation between the toothed sector 57 and toothed wheel 113 or the - axial drive means II2, said solutions being wholly lil,e those already put forward in the example of Fig. 6. Fig. 9 shows a variant of Fig. 8 wherein the crank act . ivating means already shorn in Fig. 7 are employed. In said Fig. 9 the positioning and way of working of the actuator I4 and clutch 54 remain ssubstantially unchanged as compared to Fig. 8. We have described here some possible embodiments of . the invention, but other variants are possible for a tech- . nician in this field without departing thereby from the scope of the idea of the solution. Thus the action on the stopper can be continuous or can take place step-by-step or with self-controlled proport - ional operations, etc. The action on the stopper can also be carried out axi ally; instead of the electromechanical or electrical actu tor an electro-hydraulic actuator can be fitted; where an electro-hydraulic actuator is employed, a safety valve or by-pass valve, for instance, can be fitted instead of the clutch 54, etc. It is also possible to vary the proportions and sizes and to add, remove, replace ad integrate parts, etc., all these and other variants being possible.

Claims: C L A I M S I. Commutable device for regulating the stopper (47) of a ladle (60), whereby the stopper (47) immersed in the - ladle (60) is connected to a shaft (50) moving in a direct ion axial to the stopper (47) itself and comprising advant . ageously a tract (58) cooperating with axial drive means . (57-112), said device being characterized by including in - mutual cooperation and coordination: - - an actuator means (I4) cooperating with said axial drive means (57-112), whereby intermediate safety means (54) are advantageously comprised, - - and means (I3) to control and regulate the actuator means (I4). . 2. Commutable device for regulating the stopper (47) of a ladle (60), as in Claim I, characterized by the fact that the actuator means (14) is an electrical or electro mechanical actuator means. 3. Commutable device for regulating the stopper (47) of a ladle (60), as in Claim I, characterized by the fact that the actuator means (I4) is an electro-hydraulic actuator . means. 4. Commutable device for regulating the stopper (47) of a ladle (60), as in Claim I and in one or the other of the Claims thereafter up to Claim 3 inclusive, characterized by the fact that the intermediate safety means (54) are . clutch means. 5. Commutable device for regulating the stopper (L7) of a ladle (60), as in Claim I and in one or the other of - - the Claims thereafter up to Claim 3 inclusive, character- ized by the fact that the intermediate safety means (54) are valve means° 6. Commutable device for regulating the stopper (47) of a ladle (60), as in Claim I and in one or another of the . Claims thereafter up to Claim 5 inclusive, characterized by the fact that the actuator (14) is positioned sideways to - the shaft (50), whereby there are intermediate transmission . means. 7. Commutable device for regulating the stopper (47) of a ladle (60), as in Claim I and in one or another of the Claims thereafter up to Claim 5 inclusive, characterized by the fact that the actuator (I4) lies on the same axis as the shaft (50). 8. Commutable device for regulating the stopper (47) of a ladle (60), as in Claim I and in one or another of the Claims thereafter, characterised by the fact that the con- . trol and regulation means (I3) comprise at least one regul- ating circuit (33), whereby said control and regulation means (I3) are conditioned by the level (11) in the ingot - mould (I7). 9. Commutable device for regulating the stopper (47) of a ladle (60), as in Claim I and in one or another of the Claims thereafter, characterized by the fact that the con- ditioning of the control and regulation means (13) takes place at least through one summation means (18) that also performs comparison functions. 10. Commutable device for regulating the stopper (47) of a ladle (60), as in Claim I and in one or another of the Claims thereafter, as described and shown and for the pur poses granted.

Inventors: DELLA VEDOVA, FERRUCCIO
Applicants: CEDA S.P.A.
Application year: 1981
Main classification: B22D41
IPC codes: B22D11, B22D41