EP0902734B1 - Adjusting device for setting the position of billet-support elements - Google Patents

Abstract

An adjustment device for adjusting the position of at least one strand supporting element (5) relative to a supporting stand (9, 10) carrying at least one further strand supporting element (6), of a strand guide in a continuous casting plant comprises at least one hydraulic adjustment cylinder (12) contacting a strand supporting element (5) directly or indirectly on the one side and the supporting stand (9, 10) carrying a further strand supporting element (6) on the other side, the movement of the strand supporting element (5) being detectable via a position sensor (17) and controllable by means of an automatic controller (26). In order to safely attain the high precision in positioning the strand supporting elements (5, 6) sought for a strand guide at yet a minimum expenditure and a minimum susceptibility to failure, at least one directional control valve (21A, 21B) capable of being switched via a three-level controller (26) is provided for actuating the hydraulic adjustment cylinder (12) FIG. 2.

Description

The invention relates to an adjusting device for adjusting the position of at least one Strand support element, in particular a strand guide roller, with respect to at least one further strand supporting element supporting scaffold of a strand guide in a Continuous caster, in particular steel caster, with at least one hydraulic adjustment cylinder, on the one hand, directly or indirectly on a strand support element and on the other hand attacks on the support frame, the movement of the strand support element via a Position measuring device can be detected and regulated by means of a controller.

A device of this type is known from US-A--3,812,900. This is one on one Support scaffold movably arranged by means of hydraulic adjustment cylinders in Direction to or from an opposite rigidly arranged on the scaffold Strand guide roller moves. The respective position (actual value) of the movable strand guide roller is determined by means of a measuring device and with a setpoint by means of a comparator compared. The comparator controls one if the actual value deviates from the setpoint Servo unit via which the hydraulic adjustment cylinders can be connected to the pressure source.

The servo valve technology allows a very sensitive and fast control of large outputs due to low tax payments thanks to the supportive effect of the flowing medium. The servo valve technology is mainly used in machine tool technology for sensitive Positioning tasks are used. Accordingly, both the material and also the cost of implementing the servo valve technology. The maintenance and Measures to avoid interference are also complex.

The application of the servo valve technology for the continuous casting technology allows an adjustment of the Position of the movable strand guide roller with extreme precision. The disadvantage is the high Technical expenditure on materials when using servo valve technology and contamination the same; Difficulties can arise for the rough operation of the iron and steel works.

The invention aims at avoiding these disadvantages and difficulties and presents itself the task of creating an actuator of the type described above, with the the high accuracy of positioning the desired for the strand guide Strand support elements can be achieved with certainty, but only one compared to the stand the technology requires minimal effort, both in terms of the cost of Manufacturing as well as the cost of care and maintenance. Influences resulting from the Foundry technology results, such as dust, high temperatures, splashing water originating from the Strand cooling etc. are said to have no or only minimal effects on the accuracy of the Have positioning of the strand guide.

This object is achieved in that to act on the hydraulic adjusting cylinder at least one directional control valve is provided, which has a three-position controller or a higher-level controller or a controller with pulse width output, which the of the Position measuring device detected actual value can be entered via a coupling, is switchable.

The provision of a directional control valve makes it possible significantly compared to the prior art simpler control technology. This is due to the particularly high accuracy with servo valve technology is not available, but there are significant advantages lower costs and also a much lower sensitivity to interference such as. Contamination of the oil or pressure drops or the like. It has Surprisingly shown that with the directional valve technology for continuous casting also for sensitive steel qualities that can be found.

With a controller with pulse width output, an almost constant one can also be used with directional valves Achieve control, as is typically achieved with servo or proportional valves. Instead of a variable valve opening with these continuously operating valves, a Sequence of pulse-like valve openings set at the switching valve. This allows Positions can be made with high accuracy.

Since only small volume flows are required to adjust a strand support element, the entire system, however, works with high pressures (e.g. 160 bar) is expedient in at least one hydraulic working line of the hydraulic adjusting cylinder by one Pressure medium supply station to the directional valve or from this to the hydraulic actuating cylinder leads, a throttle or orifice installed.

A preferred embodiment is characterized in that in at least one Hydraulic working line leading from a pressure medium supply station to the directional valve or from this leads to the hydraulic adjustment cylinder, a flow control valve with rectification is installed.

A flow control valve sets one of the loads and those corresponding to them Hydraulic press in almost independent adjustment speed. One on this Adjustment speed and the response and fall time of the respective directional valve coordinated design of the 3 or 5-point controller allows a very precise and direct Reaching the desired target position for all load cases.

Another preferred embodiment is characterized in that in the to and / or a hydraulic working line leading from the hydraulic adjusting cylinder to the hydraulic adjusting cylinder immediately upstream or downstream throttle or orifice is provided. As a result, the main throttle effect (or main diaphragm effect) between the Hydraulic adjusting cylinder and the upstream check valves achieved. As a result, the switching times of the check valves can be kept short and it can Vibrations of the same can be avoided. Are these chokes or orifices that additional are arranged to throttles or orifices between the pressure source and the directional control valve, provided, so there is a great variety in terms of Achieve adjustment speed of the hydraulic adjustment cylinder, but basically still It should be noted that the more chokes or orifices are provided, the larger they are can be dimensioned and are therefore less sensitive to contamination.

To achieve different over the adjustment path of the hydraulic adjustment cylinder Adjustment speeds of the piston and thus increased accuracy is preferred an additional directional valve in parallel to a throttle or orifice Flow control valve provided with rectification, expediently as a regulator Five-point controller or higher-level controller is provided.

The invention further relates to a strand guide for a continuous caster with actuator according to the invention. Here, the displacement measuring device is preferably from one arranged in parallel to the hydraulic adjusting cylinder, opposite to Hydraulic adjusting cylinder working balancing cylinder formed, on the one hand with a Support frame supporting the strand support element, in particular a support segment, and on the other hand with a supporting the strand and arranged movably with respect to the support frame Strand support element is connected directly or indirectly.

The invention is based on several in the drawing in a schematic manner illustrated embodiments explained in more detail, wherein Fig. 1 is an inventive Actuating device in a schematic representation and Fig. 2, its arrangement on a Strand guide rollers equipped strand guide, also in a schematic representation, illustrate. Figures 3 and 4 show the operation of a three-point controller and of a five-point controller depending on the control deviation. Fig. 5 illustrates one Basic circuit with a flow control valve, Fig. 6 shows the basic circuit with a 4/3-way valve with bezels. Fig. 7 shows a valve-throttle combination for realizing two adjustment speeds for the piston of a hydraulic adjustment cylinder.

In the case of a strand guide 1, a solidified strand shell 2 and another serve to support the liquid core 3 having strand 4 as strand support elements strand guide rollers 5, 6, which the strand 4 on its broad sides, i.e. 2 on its top 7 and bottom 8 touch. As can be seen in particular from FIG. 2, the lower strand guide roller 6 is on attached to a carrier 9, which is wedged by means of tie rods 10 on the carrier 9 of the lower roller 6 with a counter support 11 on which the upper strand guide roller 5 is rotatably mounted, connected is. The counter beam 11 is slidable along the tie rod 10, so that the Distance between the strand guide rollers 5, 6 is changeable. To realize a movement of the counter-carrier 11 relative to the carrier 9 is a hydraulic adjusting cylinder 12. Both the carrier 9 as well as the counter carrier 11 preferably carry out with the formation of Strand support segments a plurality of strand guide rollers 5 and 6.

The cylinder 13 of the hydraulic adjusting cylinder 12 is supported on an additional carrier 14, which is also wedged relative to the tie rod 10, so that the additional carrier 14 in its Position relative to the carrier 9 is fixed. The beam 9, the tie rod 10 and the additional beam 14 form a support frame, against which the counter-beam 11 is movable. The piston 15 of the Hydraulic adjusting cylinder 12 is preferably for uniform and radially symmetrical Force distribution designed as a hollow piston, which is penetrated by the tie rod 10. The front one End 16 of the piston 15 is supported on the counter beam 11.

Between the additional support 14 and the counter support 11 is in parallel to the Hydraulic adjusting cylinder 12 a balancing cylinder 17 is provided, which always acts on it is that the counter-carrier 11 at the front end of the piston 15 of the hydraulic adjusting cylinder 12 is present, d. H. is pressed against it. The cylinder of the balancing cylinder 17 is with the Additional support 14 and the piston connected to the counter support 11. This balancing cylinder could also be rotated by 180 ° between the additional support 14 and the Counter carrier 11 may be arranged. The balancing cylinder 17 enables play-free Positioning of the counter-carrier 11 with respect to the carrier 9 and serves, for example additionally as a displacement sensor to determine the actual position of the counter-carrier 11, as in schematic representation in Fig. 1 is shown. In this way there are bruises or contamination of the force application point of the hydraulic adjusting cylinder 12 on Counter beam 11 - that is, at the support point of the piston 15 - without negative influence on the Set position of the strand guide roller 5 to be set.

As can be seen in particular from FIG. 1, hydraulic working lines 18, 19 are each above Throttles 20 or orifices and directional control valves 21A, 21B and these controlled downstream Check valves 22A, 22B each with a chamber 23, 24 of the hydraulic adjusting cylinder 12 connectable. The respective position of the piston 15 of the hydraulic adjusting cylinder 12 - and thus the strand guide roller 5 - is over the displacement sensor, i.e. the balancing cylinder 17, determined and then its signal to a comparator 25 of a three-point controller 26 passed on. The setpoint for the position of the Piston 15 of the hydraulic adjusting cylinder 12. If the actual value deviates from Setpoint value, the three-point controller 26 comes into operation, the valve 21A with the signal + 1 and switches signal 21B with signal -1.

Which lead to the two chambers 23 and 24 of the hydraulic adjusting cylinder 12 Hydraulic working lines 18, 19 existing check valves 22A and 22B each from the hydraulic working line 18, 19 opening into the other chamber via the Control lines 27 acted upon.

According to the embodiment shown in FIG. 2, the balancing cylinder 17 is of a own hydraulic working line 28 can be pressurized. Another is Pressure relief valve 29 is provided, the force of the piston 15 of the hydraulic adjusting cylinder 12 if this is the two opposite strand guide rollers 5, 6 moved against each other, limited.

In Fig. 3, the control of the three-point controller 26 is explained in more detail, the on the ordinate Actuation of the directional control valves and the control deviation are plotted on the abscissa. If the three-point controller 26 gives the signal +1, the magnet of the directional control valve 21A switched, whereas the magnet of the directional control valve 21 B is de-energized. Is the signal of the Three-point controller 26 0, both magnets of the directional control valves 21A and 21B are de-energized; at the Signal -1 is the solenoid of the directional control valve 21A de-energized and the solenoid of the switches Directional control valve 21B.

Fig. 5 shows a slightly modified circuit with a 4/3-way valve 21C, which with a Flow control valve 30 is equipped with rectification. 6 shows a similar circuit also with a 4/3-way valve 21C, but without a flow control valve. According to this Embodiments are between the check valves 22A, 22B and the hydraulic adjustment cylinder 12 throttles 20 or orifices in addition to in front of the 4/3-way valve 21C provided chokes 20 or orifices in the hydraulic working lines 18, 19. This makes it possible to vary the speed of the Achieve hydraulic adjustment cylinder 12. The chokes or orifices can be larger be dimensioned, the more of them are provided, which has the advantage that the chokes 20 or panels are significantly less sensitive to contamination.

In the embodiment shown in FIG. 6, one leaves the upstream of the 4/3-way valve 21C provided chokes 20 or diaphragms away or dimensioned larger than that immediately before your hydraulic adjusting cylinder 12 arranged throttles 20 or orifices, the Main throttle action (or main orifice action) between the check valves 22A and 22B and the hydraulic adjusting cylinder 12 can be achieved, thereby reducing the switching times of the Check valves 22A and 22B can be kept particularly short. Be too Vibrations of the check valves 22A and 22B avoided by this measure. In principle, the arrangement of chokes 20 or orifices can be directly adjacent to Hydraulic adjustment cylinder 12, i.e. between check valves 22A and 22B and Hydraulic adjusting cylinder 12, also shown in all others in FIGS. 1, 2.5 and 7 Embodiments are realized, so that the advantages described above also set these embodiments.

In Fig. 7 is a valve-throttle combination for realizing two Adjustment speeds for the hydraulic adjustment cylinder 12 illustrated. The piston 15 of the hydraulic adjusting cylinder 12 can be moved in rapid or creep speed. At this circuit, in which the part enclosed in dash-dotted lines is identical to that 1 are in the hydraulic working lines 18, 19 additionally Throttles 31 and orifices upstream of the directional control valves 21A and 21B, each via a bypass 32, 33 can be bridged. A bridging can be done with the help of a Bypass lines 32, 33 provided directional valve 34 can be achieved via a Five-point controller is activated or deactivated. The five-point rule is through one Three-point controller 26 according to FIG. 1 with an operation according to FIG. 3 and a rapid / slow speed switch 35, the mode of operation of which is explained in FIG. 4. Approaching the piston 15 of the hydraulic adjusting cylinder 12 the switching range of the three-point controller 26, is switched to a lower speed via the rapid / creep speed switch 35, etc. by means of one of the switchable diaphragms 31, so that a more precise positioning is achieved can be. The rapid / slow speed switch 35 brings the directional valve 34 in with the signal +1 the position shown in Fig. 4 for the creep speed and with the signal 0, the directional valve 34 in the rapid traverse position in which the hydraulic medium via the bypass lines 32 and 33 flows.

Instead of the three-point controller 26, a controller with a pulse width output can also be provided.

Claims (8)

1. An adjustment device for adjusting the position of at least one strand supporting element (5), in particular a strand guiding roller (5), relative to a supporting stand (9, 10) carrying at least one further strand supporting element (6), of a strand guide (1) in a continuous casting plant, in particular a continuous casting plant for steel, comprising at least one hydraulic adjustment cylinder (12) contacting a strand supporting element (5) directly or indirectly on the one side and the supporting stand (9, 10) on the other side, the movement of the strand supporting element (5) being detectable via a position sensor (17) and controllable by means of a controller (26), characterized in that at least one directional control valve (21A, 21B, 21C) capable of being switched via a three-level controller (26) or a higher-level controller (26, 35) or a controller with a pulse-width output into which the actual value detected by the position sensor (17) may be entered via a coupling is provided for actuating the hydraulic adjustment cylinder (12).
2. An adjustment device according to claim 1, characterized in that a throttle (20) or screen is installed in at least one hydraulic working duct (18, 19) of the hydraulic adjustment cylinder (12), leading from a pressure fluid supply station to the directional control valve (21A, 21B, 21C) or from the latter to the hydraulic adjustment cylinder (12).
3. An adjustment device according to claim 1, characterized in that a current control valve (30) with rectification is installed in at least one hydraulic working duct (18, 19) leading from a pressure fluid supply station to the directional control valve (21A, 21B, 21C) or from the latter to the hydraulic adjustment cylinder (12) (Fig. 5).
4. An adjustment device according to one or several of claims 1 to 3, characterized in that a throttle (20) or screen is provided in a hydraulic working duct (18, 19) leading to and/or away from the hydraulic adjustment cylinder (12), so as to immediately precede respectively follow the hydraulic adjustment cylinder (12) (Fig. 6).
5. An adjustment device according to one or several of claims 1 to 4, characterized in that an additional directional control valve (34) is arranged in parallel with a throttle or screen or a current control valve with rectification (Fig. 7).
6. An adjustment device according to claim 5, characterized in that a five-level controller (26, 35) or a higher-level controller is provided as a controller (Fig. 7).
7. A strand guide for a continuous casting plant, in particular a continuous casting plant for steel, comprising an adjustment device according to one or several of claims 1 to 6.
8. A strand guide according to claim 7, characterized in that the position sensor (17) is constituted by a balancing cylinder (17) arranged in parallel with the hydraulic adjustment cylinder (12) and working diametrically opposed to the hydraulic adjustment cylinder (12) and, on the one side, being connected with a supporting stand (9, 10), in particular a supporting segment, carrying a strand supporting element (6), and, on the other side, being connected directly or indirectly with a strand supporting element (5) supporting the strand (4) and arranged to be movable relative to the supporting stand (9, 10) (Fig. 2).

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