JPH0586308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a clamping device for soft clamping a long side frame of an assembled mold for continuous casting.

[Prior art]

An assembled mold for continuous casting has a structure in which, for example, a pair of short-side copper plates is slidably arranged between a pair of long-side copper plates, and the pair of long-side copper plates are sandwiched between a pair of long-side mold frames and clamped by a clamping device. When changing the width during casting, replacing the immersion nozzle during casting, or performing high-speed casting, it is possible to easily move the short side copper plate, absorb the displacement of the mold due to thermal expansion force, and always maintain the minimum required height during casting. It is necessary to clamp the short side copper plate with clamping force.

As the latest conventional clamp devices, the following ones have been proposed.

(i) Utility Model Application Publication No. 60-56141 This is an assembly mold in which the clamping force is divided by a two-stage (two types) spring force to prevent scratches on the long side frame that occur when changing the width during casting. It is prevented.

(ii) Utility Model Publication No. 60-56142 In this assembly mold, the cylinder for releasing the clamping force is a two-stage cylinder to prevent scratches on the long side frame that occur when changing the width during casting.

[Problems to be solved by this invention]

However, in the conventional device described above, the following problems remain unsolved.

(i) The thermal expansion force of the short side copper plate generated during casting varies depending on the operating method, such as molten steel temperature, casting speed, mold cooling temperature depending on the steel type, etc., and the clamping force during operation must be constantly changed. , in the above-mentioned conventional technology, there is no idea of absorbing thermal expansion force, but a constant value of spring force (cylinder force),
Unable to adapt to change.

The above-mentioned conventional technology aims to maintain a constant distance of about 0.5 mm between the long side frame and the short side frame when changing the width during casting.

(ii) Changing the width during casting causes changes in static iron pressure in the mold, bulging force, etc. (for example, when there are many
However, in the conventional technology, the amount of opening of the long side frame (the amount of distance between the long and short sides) when changing the width is only kept constant, and no measures are taken against the change.

If the clamping is done at a constant value (spring or cylinder) despite the phenomena like () and (), plastic deformation will occur in the part of the short side copper plate where the temperature rises the most (near the meniscus). The bullion plugs in and causes a breakout.

In addition, since it is clamped at a constant value, scratches occur on the long side copper plate when changing the width during casting under poor conditions. Furthermore, the scratches caused by the above-mentioned insertion of the base metal are enlarged.

This invention was made to solve these problems, and its purpose is to be able to clamp with an optimal clamping force that corresponds to changes in static iron pressure and bulging force caused by width changes during casting, and to clamp An object of the present invention is to provide a clamp device that can absorb displacement due to thermal expansion force.

[Means to solve the problem]

As shown in FIGS. 1 to 3, the clamp device of the present invention uses a tie rod 5 whose base end is fixed to one long side frame 3 and whose tip protrudes through the other long side frame 4. In the clamp method, a compressed spring 7 that can press the free long side frame 4 is disposed between the tip of the tie rod 5 and the free long side frame 4, and the spring 7 is compressed to press the free side long side frame 4 and the free side long side frame 4. An unclamp cylinder 9 capable of pressing the tie rod 5 is interposed between the tie rod 5, a load detector 11 is provided on the tie rod 5 to detect the load applied to the tie rod, and a pressure control valve 12 capable of adjusting the hydraulic pressure of the unclamp cylinder 9 is installed to detect the load. The control unit 11 is configured to be controlled by computing units 18 and 19 based on the detection signal of the unit 11.

Further, the unclamping cylinder 9 is of a two-way operating type, and a removable adjustment piece 14 is interposed between the cylinder 9 and a stopper 13 that prevents movement of the free long side frame in the unclamping direction.

[Effect]

The long side clamping force is constantly detected by the load detector 11, and the pressure control valve 12 is controlled by the computing units 18 and 19, and the pressure control valve 12 is controlled according to changes in static iron pressure and bulging force caused by changing the slab width during casting. The amount of unclamping by the hydraulic pressure of the unclamping cylinder 9 is continuously controlled, and the optimum long side clamping force F can be obtained.

F (= static iron pressure + bulging force + soft clamping force) = W - w W: Reference long side clamping force by disc spring w: Unclamping force by hydraulic pressure Expansion force f due to thermal expansion is also detected by the load detector 11. , similarly, the optimum long side clamping force F can be obtained.

F=W-w-f Also, during casting, the adjustment piece 14 is attached and control is performed with a relatively small amount of unclamping, and when washing with water, the adjustment piece 14 is removed and the amount of unclamping required for cleaning is controlled with a relatively large amount. 〓To form a gap.

The stopper 13 is a stopper that limits the amount of protrusion of the piston rod, and is used to prevent the gap between the molds from expanding abnormally even if the piston rod is pushed in due to a hydraulic abnormality during normal operation. However, when washing with water, it is necessary to expand the opening more than this, so by removing the adjusting piece 14, the amount of pushing can be increased by that amount.

〔Example〕

The present invention will be described below based on an illustrated embodiment.

As shown in FIG. 1, the assembled mold has a pair of short side copper plates 1 slidably arranged between a pair of long side copper plates 2,
It has a structure in which the long side copper plate 2 is sandwiched between a pair of molded frames 3 and 4, and both left and right ends of the frames 3 and 4 are clamped by a pair of upper and lower clamping devices,
The fixed mold frame 3 is fixed to a support member (not shown), and the free mold frame 4 is movably supported by the support member.

The clamping device generally has a double nut 6 at the proximal end.
It has a tie rod 5 which is fixed to the fixed mold frame 3 and whose tip protrudes through the free mold frame 4, a pressing means for pressing the free mold frame 4, and an unclamping means for releasing this pressing. ing.

In such a clamping device, in the present invention, a spring 7 is attached in a compressed state to the tip of the tie rod 5 via a double nut 8, and an unclamp cylinder 9 capable of pressing the tie rod 5 against the free side mold frame 4 is attached to the support member 10. Installed via,
A load cell 11 is attached to the middle part of the tie rod 5. Furthermore, as shown in FIG. 2, the unclamping cylinder 9 is of a two-way operating type, a pressure control valve 12 with a motor is added to the hydraulic circuit, and a double nut 13 as a stopper is installed between the piston rod 9B and the cylinder 9. An adjustment ring 14 is interposed therebetween.

The load cell 11 is incorporated and used as an intermediate member connecting the divided rods 5.
Since only tensile stress is always applied to the rod 5, the joint portion of the rod 5 is connected by a fine thread. Note that the installation location of the load cell 11 may be within the range shown in FIG.

Further, when the fixed side mold frame 3 and the tie rod 5 are attached by a through type, a compressive stress detector can be provided between the tie rod end lock nut 6 and the frame 3.

As shown in FIG. 2, the unclamping cylinder 9 is movable in two directions by a directional switching valve 15, and a conventional pressure reducing valve 16 and an additional pressure control valve 12 are used to control high pressure in the unclamping direction.
Low-pressure dual-pressure control is possible. That is,
When the pressure control valve 12 is connected to the low pressure drain of the pressure reducing valve 16 via the switching valve 17 and the low pressure drain is closed by the switching valve 17, the circuit is maintained at the high pressure set value by the high pressure drain of the pressure reducing valve 16, and the switching valve 17 When the low pressure drain is opened by the pressure control valve 12, the circuit becomes low pressure. Furthermore, motor 12
By controlling A, the low pressure can be adjusted.

As shown in FIG. 3, this pressure control valve 12 for low pressure is connected to the detection signal of the load cell 11,
The microcomputer 19 controls the pressure to an appropriate level based on command signals from the vidicon 18.

Incidentally, as shown in FIG. 3, the pressure reducing valve 16 may be omitted and the high pressure and low pressure may be directly controlled by the pressure control valve 12.

In the above configuration, the load cell 11 incorporated in the tie rod 5 constantly detects and monitors the long side clamping force during casting and non-casting, and based on that value, the motorized pressure control valve in the hydraulic circuit 12
It is controlled by the CPU so that the required long side clamping force F is always maintained.

F=W-w (1) F: Clamping force according to casting width (variable) W: Standard long side clamping force due to disc spring force (constant value) w: Unclamping force due to hydraulic pressure (variable) , can be determined as follows.

F = (Static iron pressure in the mold) + (Bulging force at the lower end of the mold) + (Soft clamping force) The static iron pressure in the mold and the bulging force are values determined by the casting width, and the soft clamping force is constant based on past experience. Use value.

Therefore, the required clamping force that changes due to the width change is calculated using equation (1), and the state in which the short side copper plate is always clamped with the optimum long side clamping force is maintained. Naturally, the optimal clamping force is used when changing the width during casting.

Next, although the amount of thermal expansion of the short side copper plate that occurs from the initial stage of casting varies depending on the operating conditions, it is estimated to be a displacement of 1.0 to 1.5 mm when calculated from the temperature measurement results on the surface of the copper plate. (When the short side length is 250 mm) This displacement is restricted by the long side clamping force, and the smaller this is, the better. Ideally, the long side frame should be displaced back and forth depending on the amount of thermal expansion. Therefore, in order to minimize the compressive stress applied to the short side copper plate, it is necessary to suppress the long side clamping force to a minimum.

Therefore, in order to maintain the movement of equation (1) above, the expansion force generated by thermal expansion is applied to the load cell 11.
The pressure control valve 12 is controlled to reduce the force by f, and the unclamping force due to the hydraulic pressure is set to w'=w+f, which is the optimum clamping force.

F+f=W-w F=W-w-f (2) This absorbs the thermal expansion force applied to the short side copper plate.

As mentioned above, the long side clamping force that changes depending on the static iron pressure, bulging force, and thermal expansion force is set at the initial stage, and the standard disc spring force W and the low pressure hydraulic pressure (w-
w') and by performing feedback control incorporating the load cell 11 of the tie rod 5, the optimum long side clamping force was always maintained.

Next, at the end of casting, there is powder and other deposits on the inner surface of the mold. By cleaning this regularly, you can prevent scratches caused by foreign objects getting caught when moving the short side (especially when the casting width is small). can.

The maximum distance between the long and short sides during casting is 1.5 to 2.0 mm, and the distance between the sides required during high-pressure water cleaning is, for example, 10 mm.
The unclamping amount can be adjusted in two stages using a two-way unclamping cylinder 9, a pressure control valve 12, and an adjusting ring 14.

That is, as shown in Fig. 1, during casting,
In order to prevent the gap between the long and short sides from being more than 1.5 to 2.0 mm at maximum, insert the adjustment ring 14 (distance piece) for the distance required for cleaning (for example, 10 mm) (see Figure 1) to control the pressure. It is controlled at low pressure by valve 12. In the unclamp cylinder 9, the pressure in the hydraulic chamber on the piston rod 9B side is controlled, and as the piston rod 9A presses the tie rod 5, the free side mold frame 4
moves.

When cleaning the side surface of the short side copper plate 1 with high-pressure cleaning water during online non-casting (including when the machine is stopped), the adjustment ring 14 is removed. At this time, since the ring 14 cannot be removed in the state shown in FIG. 1, the flow path is switched by the directional control valve 15 (see FIG. 2) to remove the hydraulic pressure from the piston rod 9B side, and the ring 14 is removed. Next, the directional control valve 20 is switched, the pressure is switched to high, the piston rod is moved in the unclamping direction, and the free side mold frame is moved, for example, by 10 mm.

Figure 4 shows a clamping force control graph. In the past, load fluctuations of 1.5 to 3 tons were uncorrected, but with the present invention, arbitrary settings are possible, and arbitrary soft clamping operations are possible. It became. As a result, the deformation on the short side can be reduced to almost zero, and the mold life is now 1200 heat (with only scratches and no deformation), compared to the conventional 800 heat (charge).
It is now possible to use it.

〔Effect of the invention〕

As mentioned above, the clamping device according to the present invention is configured to detect the load on the tie rod and adjust the spring force of the tie rod with the hydraulic pressure of the unclamp cylinder based on this detection signal, so that the width of the slab during casting can be adjusted. It is possible to continuously control the optimum clamping force in response to changes in static iron pressure and bulging force due to changes in iron pressure and bulging force, and it is possible to constantly control the optimum clamping force while absorbing the thermal expansion force generated during casting (which varies depending on operating conditions). Can be maintained.

Since the above two points were made possible, the number of scratches on the long side copper plates that occurred when changing the width during casting was drastically reduced, and the life of the mold was doubled.

Partial plastic deformation (concave phenomenon) in the high temperature region (near the meniscus) of the short side copper plate is eliminated, extending the mold life.
It has increased by 1.5 to 2 times.

Since the above-mentioned concave deformation is eliminated, there is no gap between the long and short sides of the mold that occurs when replacing the immersion nozzle during casting, and there is no need to insert metal when replacing the nozzle, making the nozzle replacement work stable and easy. The technology was established.

The short sides of the mold can be washed with high-pressure water while not being cast online, and the short sides of the copper plate are always kept clean, making the mold free from scratches.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional plan view showing the clamping device of the present invention, Fig. 2 is its hydraulic circuit diagram, Fig. 3 is a schematic diagram showing the device together with control equipment, and Fig. 4 is a graph showing the clamping force. . 1...Short side copper plate, 2...Long side copper plate, 3...Fixed side mold frame, 4...Free side mold frame, 5...Tie rod, 6...Double nut,
7...Disc spring, 8...Double nut, 9...Unclamp cylinder, 10...Support member, 11...
Load cell, 12...Pressure control valve with motor, 1
3...Double nut, 14...Adjustment ring, 15
...Direction switching valve, 16...Pressure reducing valve, 17...Switching valve, 18...Procontroller/visicontroller, 19...Microcomputer.

Claims (1)

[Scope of Claims] 1. A clamping device for clamping opposing long side frames of an assembly mold for continuous casting, wherein the base end is fixed to one long side frame and the tip protrudes through the other long side frame. a compressed spring disposed between the tip of the tie rod and the other free long side frame and capable of pressing the free long side frame, and the free long side frame and the tie rod. an unclamp cylinder interposed between the two and capable of pressing the tie rod;
A load detector provided on the tie rod to detect the load applied to the tie rod; a pressure control valve capable of adjusting the hydraulic pressure of the unclamp cylinder; and a pressure control valve capable of controlling the pressure control valve based on a detection signal of the load detector. An assembly mold clamping device for continuous casting characterized by being equipped with a computing unit. 2. The unclamping cylinder according to claim 1 is a two-way operating type, and is characterized in that a removable adjustment piece is interposed between the cylinder and a stopper that prevents movement of the free side long side frame in the unclamping direction. Assembly mold clamping device for continuous casting.