JPH0688115B2 - Pinch roll pressing force control device - Google Patents

Description

The present invention relates to a pinch roll pressing force control device in a round billet continuous casting facility.

[Prior Art] Generally, a pinch roll of a continuous casting facility is rotationally driven by an electric motor or the like to pull out a billet. This pinch roll is moved up and down by a hydraulic cylinder and presses the billet by the pressure on the head side of the cylinder. The amount of reduction of the billet can be adjusted by increasing or decreasing the distance between the piston and the roll by using the distant piece.

This pinch roll is moved up and down by an operating pressure supplied from a high-pressure hydraulic pipeline of, for example, about 100 kg / cm ^{2 in} order to pressurize the dummy bar with a strong force at the start of casting, and when pressing the billet, The head side of the hydraulic cylinder is switched to a relatively low pressure hydraulic line of, for example, about 20 kg / cm ² in order to maintain the friction force necessary to transmit the rotational driving force, and the rod side is connected to the return pipe to the tank. Combined with the road.

[Problems to be Solved by the Invention] However, in these conventional continuous casting facilities, it is necessary to adjust the distant piece according to the wear of the pinch rolls, and the adjustment management thereof is generally extremely difficult.
In addition, when casting different-sized slabs, it is necessary to adjust the distant piece according to the size of the slab each time.

In particular, in the case of casting a round billet, if the pressing force of the pinch roll is increased more than necessary by adjusting the distant piece, the round billet will be greatly deformed and the roundness will exceed the allowable limit. Further, if the pressing force is weak, there is a risk of causing defective operations such as defective drawing of the slab or dropping of the slab.

Figure 2 shows the pinch roll pressing force and the deformation amount of the round billet (Δ
The relationship of h) is shown. In this figure, the curve is the calculated value and the line A is the allowed value. Also, The diameter and drawing speed of the round billet are 210φ and 1.5m, respectively.
/ min, 170φ, 2.0m / min, 170φ, 2.4m / min, 170φ, 2.8m / m
It is the measured value of in. The substantial deformation amount is 4xΔh.

Here, the calculated value of the deformation amount (Δh) is expressed by the following equation.

However, P: Rolling amount B: Rolling width R: Roll radius ρ _K : Deformation coefficient As is clear from Fig. 2, as the casting speed increases, the slab deformation resistance decreases and the cylinder head has 20 kg / When the hydraulic pressure of cm ² is applied, the allowable value is exceeded when the speed is 2.2 m / min or more.

For this reason, the head side of the hydraulic cylinder that pressurizes the slab through the pinch roll is connected to the high pressure hydraulic pressure line, and the rod side is connected to the return pressure line. We have developed a control device that has a proportional pressure reducing valve and can freely change the pressing pressure of the pinch roll by this electromagnetic proportional pressure reducing valve.

This conventional control device can control the slab pressing force in the range of 770 to 3840 kg, and can control the minimum pressing force without adjusting the distant piece according to the wear of the pinch roll. Also, when casting round billets having different sizes, round billets having roundness within a predetermined limit can be cast without adjusting the distance piece.

However, in this control device, since the return line on the rod side of the hydraulic cylinder is common to the return lines of the other hydraulic devices in the continuous casting equipment, the back pressure is unstable and the pressing force is unstable. Become. In addition, since the hydraulic pressure is not supplied to the head side of the hydraulic cylinder at the time of power failure, there is a risk of falling slab.

In order to solve this problem, the return line on the rod side can be separated from other hydraulic devices, and a pressure loss at the time of power failure can be solved by providing an outflow prevention device.
However, when such a means is used, the circuit and equipment are complicated and the cost is extremely high.

The present invention has been made in view of the above, a simple and low cost pinch roll pressing force control device that can adjust the pressing force of a pinch roll in a wide range and can cast round billets of various sizes with high roundness. The purpose is to provide.

[Means for Solving the Problems] A pinch roll pressing force control device according to the present invention is configured so that one of a head side and a rod side of a hydraulic cylinder for pressing a pinch roll that presses a slab via a rod is hydraulically operated. An operation direction switching valve that is connected to the supply conduit and the other is connected to the return conduit to move the cylinder piston up and down, and in the conduit between the rod side port of this operation direction switching valve and the rod side of the cylinder. And a pressure reducing valve with an electromagnetic proportional relief arranged in a pipe connecting the rod side port of the electromagnetic cutoff valve to the hydraulic pressure supply pipe. It is possible to control the supply pressure to the rod side, which opposes the predetermined pressure on the head side communicating with the hydraulic pressure supply line, through the attached pressure reducing valve, and to control the minimum pressing force of the pinch roll. To do.

[Operation] In this pinch roll pressing force control device, when the pinch roll is moved, the working direction switching valve supplies the working fluid from the hydraulic pressure supply conduit to the head side or the rod side of the cylinder, and the opposite cylinder end portion. Is connected to the return line to the tank. When pulling out the slab, a predetermined hydraulic pressure is supplied from the hydraulic pressure supply line to the head side of the cylinder, and a hydraulic pressure is supplied to the rod side from the hydraulic pressure supply line by the pressure reducing valve with electromagnetic proportional relief. Is controlled over a wide range, so that the minimum pressing force of each pinch roll can be controlled independently of the operation of other hydraulic devices.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Embodiment] FIG. 1 shows a hydraulic circuit of a pinch roll pressing device according to an embodiment of the present invention, in a state in which a slab is pressurized. The pinch roll 1 is composed of a pair of rollers arranged on the upper and lower sides of the round billet 2, and the upper roller of this pinch roll is rotationally driven by an electric motor 3 which is a drive unit, and the amount of reduction with respect to the round billet 2 is restored. It is controlled by a dynamic hydraulic cylinder 4. The head-side end portion 4a and the rod-side end portion 4b of the hydraulic cylinder 4 are connected to the pipe lines 7 and 8 via a joint 5 with a check valve on both sides and a flexible pipe line 6, respectively.

The pipe lines 7 and 8 are connected to a high pressure hydraulic pressure supply pipe line 9, a low pressure hydraulic pressure supply pipe line 10 or a return pipe line 11 to the tank via an operation pressure switching valve 12 and an operation direction switching valve 13. This hydraulic supply line 9,
Reference numeral 10 is a common hydraulic line for supplying pressure oil to each hydraulic device of the continuous casting facility, and for example, pressure oils of 1000 kg / cm ² and 20 kg / cm ² are constantly supplied, respectively.

The actuation pressure cutoff valve 12 connects the hydraulic pressure supply port of the actuation direction switching valve 13 to the hydraulic pressure supply conduit 9 or 10 by exciting the actuation coil 12a or 12b.

The operating direction switching valve 13 supplies the hydraulic pressure supplied from the operating pressure switching valve 12 to one of the head-side end 4a and the rod-side end 4b of the cylinder 4, and the liquid at the other end from the drain port. By connecting the pressure to the return pipe, the pressing direction of the hydraulic cylinder 4 is switched, the dummy bar is pressed and lowered, and the slab 2 is pressed and pulled out or the pinch roll 1 is returned to the original position after the operation is completed. It acts to return.

Further, in the pipe line 8 that connects the rod side port of the operation direction switching valve 13 and the rod side end of the hydraulic cylinder 4, an electromagnetic valve formed in a 2-port 2-position switching valve whose one end side is pressed by a wobble. A shutoff valve 14 is provided. And this solenoid shutoff valve
The rod side port of 14 is provided with a hydraulic pressure supply line 10 via a line 15 in which an electromagnetic cutoff valve 16 and a pressure reducing valve with an electromagnetic proportional relief are arranged.
Are linked to.

This electromagnetic proportional relief pressure reducing valve 17 is a normal one that combines an electromagnetic proportional pilot relief valve and a pressure reducing valve with relief, and even if the inlet side pressure, that is, the pressure of the hydraulic pressure supply pipe line 10 fluctuates, The pressure on the rod end 4b side of the cylinder 4 is maintained at a set pressure lower than the pressure on the inlet side. Then, the set pressure on the rod end 4b side can be adjusted by the input current through the amplifier 18 for the spring force that sets the pilot pressure. That is, when the pressure on the rod end 4b side is lower than the set value, it flows from the hydraulic pressure supply line 10 to the outlet side, and when the pressure on the rod end 4b side is higher than the set value, the outlet side is communicated with the drain line 19 and, therefore, the rod end 4b. The outlet pressure on the side is always kept at the set value.

Further, a balancing valve 20 is provided on the low pressure inlet port side communicating with the hydraulic pressure line 10 of the operating pressure switching valve 12, and a flow control valve 21 with a check valve is provided on the outlet side of the operating direction switching valve 13. There is. The check valve 22 and the relief valve 23 are returned to the return line for safety when abnormal pressure is applied to each end of the cylinder 4.

Next, the operation of the pinch roll pressing force control device will be described.

First, when pressurizing and lowering the dummy bar, the exciting coil 12b of the operating pressure switching valve 12 is excited to connect the hydraulic pressure supply conduit 9 to the hydraulic pressure inlet port of the operating direction switching valve 13. The operation direction switching valve 13 has its exciting coil 13b excited so that the head end side outlet port communicates with the working pressure inlet port, and the rod side end portion
Connect 4b to return line 11. Further, the electromagnetic cutoff valves 14 and 16 are pressed to the left in the figure by the springs in the non-excited state.

The actuation of each of these exciting coils can be appropriately performed through a normal control device.

Therefore, the hydraulic oil is supplied from the high-pressure hydraulic pressure supply pipe 9 to the head side end 4a of the cylinder 4 via the line 7, and the rod side end 4b is pressed to the open position by the spring.
14, the pipe 8 communicates with the return pipe 11 via the flow control valve 21 and the check valve with pilot. Therefore, the upper roller of the pinch roll 1 can press the dummy bar with a strong force and pull it out by rotating the electric motor or the like.

And when removing the dummy bar and pulling out the slab,
The electromagnetic coil 12b of the operating pressure switching valve 12 is de-energized, the electromagnetic coil 12a is excited, and the electromagnetic cutoff valves 14 and 16 are excited to switch the respective valves to the illustrated state.

In the slab pressurizing state shown in the figure, a constant hydraulic pressure of, for example, 20 kg / cm ² is supplied from the hydraulic pressure line 10 to the head-side end 4a of the cylinder 4 by the balancing valve 20 via the line 7. At the rod-side end 4b, the pressure adjusted by the pressure reducing valve 17 with the electromagnetic proportional relief is also supplied from the hydraulic pressure supply line 10 to the lines 15 and 8.
Is supplied via. The outlet-side set pressure of the pressure reducing valve 17 is adjusted via an appropriate controller according to the size of each round billet and the drawing speed. Therefore, the upper roller of the pinch roll 1 is pressed by a force corresponding to the pressure difference between the head side end portion 4a and the rod side end portion 4b of the cylinder, and when used in a hydraulic cylinder similar to the conventional one, the upper roller is 409 to 9640 kg. The pressing force can be controlled within the range.

If, for example, a power failure occurs in the presence of this slab, the pressure reducing valve 17 is closed, the shutoff valve 14 is switched to the open position, and the rod-side end 4b is communicated with the return pipe line 11. Since the pressure is maintained at the side end portion 4a, there is no risk of causing an operational abnormality such as falling of a slab.

When the cylinder 4 is raised after the casting is completed, the shut-off valves 14 and 16 are de-energized and switched to the left in the figure, and the exciting coils 12a and 13b of the operating pressure switching valve 12 and the operating direction switching valve 13 are de-energized. Then, the exciting coils 12b and 13a are excited to move the switching valves 12 and 13 to the left in the drawing. As a result, the rod-side end 4b of the cylinder 4 is passed from the hydraulic pressure supply pipe 9 through the pipe 8.
Is supplied with pressure oil, the head side end 4a is communicated with the return pipe 11 via the pipe 7, and the piston rod is raised.

In this embodiment, the pressure oil is supplied from the high pressure and low pressure hydraulic pressure supply pipes, but it is also possible to supply the pressure oil to each end of the cylinder from one hydraulic pressure pipe.

[Effect] As is apparent from the above, according to the present invention, the pressing force of the pinch roll for pressing the slab can be controlled in an extremely wide range by the control device having an extremely simple structure and low cost,
Round billets of various sizes can be cast with minimal deformation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a pinch roll pressing force control device according to an embodiment of the present invention, and FIG. 2 is a graph diagram showing the relationship between pinch roll pressing force and billet deformation amount. . 1 ... Pinch roll, 2 ... Billet, 3 ... Drive device, 4 ... Cylinder, 4a ... Head side end, 4b ... Rod side end, 9,10 ... Hydraulic supply line, 12 ...... Operating pressure switching valve, 13 ...... Operating direction switching valve, 14,16 ...... Electromagnetic cutoff valve, 17
...... Reducing valve with electromagnetic proportional relief, 20 …… balancing valve.

Claims (1)

[Claims] 1. A cylinder piston is vertically moved by connecting one of a head side and a rod side of a pinch roll pressing cylinder for pressing a cast piece through a rod to a hydraulic pressure supply pipe line and the other to a return pipe line. Direction switching valve that moves in the direction, an electromagnetic cutoff valve disposed in the conduit between the rod side port of this operation direction changeover valve and the rod side of the cylinder, and the rod side port of this electromagnetic cutoff valve With a pressure reducing valve with an electromagnetic proportional relief arranged in a pipeline connected to the hydraulic pressure supply pipeline,
Through this pressure reducing valve with an electromagnetic proportional relief, it is possible to control the supply hydraulic pressure to the rod side that opposes the predetermined pressure on the head side that communicates with the hydraulic pressure supply pipeline, and to control the minimum pressing force of the pinch roll. A pinch roll pressing force control device characterized in that