JPS5929350B2 - Continuous casting machine slab fall prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a falling slab prevention device for a continuous casting machine that solidifies and forms molten metal. This invention relates to a falling slab prevention device for a continuous casting machine that can prevent falling slabs.

Generally, in a continuous casting machine for molten metal, a slab to be cast is guided by guide rolls, supported by pinch rolls, and pulled out.

However, at the beginning of operation of the continuous casting machine, the dummy bar is guided by guide rolls, supported by pinch rolls, and pulled out before the slab.

This pinch roll is equipped with a pressing hydraulic cylinder and a driving electric motor to support and pull out the slab or dummy bar.

There are two types of continuous casting machines: vertical continuous casting machines and S-type continuous casting machines.

Especially in the case of a vertical continuous casting machine, most of the weight of the slab or dummy bar is placed on the pinch rolls, so the role of the pinch rolls is very important.

However, with this vertical continuous casting machine, failures in the hydraulic power source or hydraulic system of the hydraulic cylinder for pressing slabs or dummy bars,
Alternatively, there is a high risk that the slab or dummy bar will fall due to a decrease in the coefficient of friction due to the adhesion of oil and fat between the slab or dummy bar and the pinch rolls.

Also, in the S-type continuous casting machine, there are malfunctions in the sequence,
There is a risk that the slab or dummy bar may fall due to a failure of the hydraulic system or a decrease in the coefficient of friction due to the adhesion of oil and fat between the slab or dummy bar and the pinch roll.

In any of these cases, if the slab or dummy bar were to fall, it would inevitably cause serious damage to various machinery and equipment, although this would not result in human injury.

However, the conventional fall prevention device for slabs or dummy bars is
This is hardly considered in mold continuous casting machines.

Also, no particularly reliable and effective prevention method has been implemented for vertical continuous casting machines.

FIG. 1 shows a sectional view of a slab drawing device in a typical vertical continuous casting machine.

The outline of the equipment will be explained below with reference to this figure, and the mechanism for preventing falling of slabs or dummy bars and its problems will be explained in particular.

The slab 1 (or dummy bar) completes solidification at the guide rolls 2, is supported by the pinch rolls 3, and is pulled out.

This pinch roll 3 is moved to the slab 1 by a hydraulic cylinder 4.
be forced to.

The slab 1 passes through the pinch rolls 3, further descends, and is cut by a cutter 5.

Since this cutting machine 5 is controlled in synchronization with the drawing speed of the slab by a cutting machine lifting device 6, the slab 1 is cut by the cutting machine 5 while descending.

The cut slab 1 is stored in a carrier bag 8 containing a roll 7.

This carrier bag 8 is suspended by a wire 9 and the ball 1
A bag holder that is raised and lowered along the line 0 is mounted on a frame 11 and is lowered to the lowest point by a lifting device 12.

Here, the frame 11 is rotated around the pin 14 by the tilting cylinder 13, and the slab 1 is rotated by the rolls 7 and 16.
It is sent onto the table 17 and carried out of the continuous casting machine.

In the above case, originally the slab 1 is always controlled by the pinch rolls 3,
That is, the mechanism is such that it is prevented from falling by controlling the speed of the pinch roll electric motor and controlling the pressing force of the cylinder 4.

Furthermore, in case of accidental falling of the slab due to a failure of the hydraulic power source of the cylinder 4 or a decrease in the coefficient of friction due to the adhesion of oil and fat on the surface of the pinch roll 3, the slab is caught by a carrier bag 8, and the falling slab is prevented from falling. It has a structure in which energy is absorbed by the winding wire 9.

That is, the carrier bag 8 for receiving and transferring the slab or dummy bar serves as a stopper to prevent the slab or dummy bar from falling.

However, the carrier bag 8 cannot serve as a stopper against accidental falling of the slab while the carrier bag 8 is sending the slab cut by the cutter 5 to the conveying table 17 side.

That is, during this time, the carrier bag 8 is not in a position to receive the falling slab, and if the slab falls during this period, the falling distance of the slab is long, and accidents such as cutting of the wire 9 and damage to the equipment occur.

In other words, it is impossible to completely prevent falling slab accidents with conventional equipment.

The purpose of the present invention is to improve the shortcomings of the prior art and to provide a method for preventing falling slabs of a continuous casting machine, which can quickly and reliably respond to falling slabs caused by various causes and prevent falling slabs. The goal is to provide equipment.

This object of the invention can be achieved by the invention as summarized below.

That is, in a slab or dummy bar drawing device of a continuous casting machine, a slab speed detection device includes a speed detection roll unit that measures a slab descending speed completely independently of the drive system of the slab pulling device; If the measured value of the slab speed detection device exceeds the measurement error range relative to the predetermined drawing speed, or if an abnormal pressure drop occurs in the hydraulic circuit for pinch roll reduction of the slab pulling device. In this case, this can be achieved by a slab fall prevention device for a continuous casting machine characterized by including an emergency hydraulic pressure guaranteeing device for guaranteeing the hydraulic pressure of the pinch roll reduction hydraulic circuit by means of an emergency hydraulic circuit.

In other words, the characteristic components of the slab fall prevention device according to the present invention are a slab speed detection device and an emergency hydraulic pressure guarantee device having an emergency hydraulic circuit attached to the pinch roll lowering hydraulic circuit.

In addition, the characteristic function of these devices is that the slab speed detection device measures the descending speed of the slab completely independently of the drive system of the slab pulling device, and that the measured value and the predetermined slab pulling speed are and the set value, and if a difference greater than the measurement error occurs, a signal is sent to the emergency hydraulic circuit.

In addition, the emergency hydraulic pressure guarantee system uses an emergency hydraulic circuit to normally apply pressure to the slab pressing side of the pinch roll reduction cylinder in the case of the above-mentioned abnormal slab drop and when the pressure in the pinch roll reduction hydraulic circuit falls below the set value. It is to ensure that the hydraulic pressure is higher than the pressure.

Embodiments of the present invention will be described below with reference to FIGS. 2, 3, and 4.

FIG. 2 shows a cross-sectional view of a pinch roll that presses down the slab or dummy bar to perform the pulling operation when pulling out the slab 1 or inserting and pulling out the dummy bar, as well as a sectional view of the roll unit for detecting the velocity of the slab of the present invention.

In the following description, the slab or dummy bar will be simply referred to as a slab, and the insertion or withdrawal will be simply referred to as "pulling out", but the content shall include both.

Pinch rolls 3A, 3B, 3C, 3D, 3E, and 3F located below the slab guide rolls 2 that sandwich the slab 1 are hydraulic cylinders 4A, 4B, respectively.

The slab is pulled out while being pressed against the slab 1 by 4C, 4D, 4E, and 4F.

In the present invention, a slab speed detection roll 18 for measuring the descending speed of the slab during slab drawing work and a hydraulic cylinder 19 for pressing the roll 18 are arranged between the pinch rolls 3B and 30.

Therefore, according to this roll unit for detecting the falling rate of slab, it is possible to measure the actual falling rate of slab completely independently of the drive system of the slab pulling device.

FIG. 3 shows an explanatory diagram of a slab speed detection device which is one of the features of the present invention, and shows a pinch roll 3B.

3E and a cross-sectional view of a portion including the slab speed detection roll 18, and a system explanatory diagram of various devices related to these.

First, the normal pinch rolls 3B and 3E are driven by an electric motor 23 that is adjusted and controlled by a thyristor 21 and an automatic speed regulator 22 so that the slab drawing speed is set in advance by a speed setting device 20.

Other pinch rolls 3A, 3C, 3D. 3F is driven in the same manner.

In the present invention, the speed signal of the pulse generator 24 connected to the speed detection roll 18 is constantly compared with the set drawing speed by the speed setting device 20, and if a difference greater than the measurement error occurs, the speed signal is amplified by the amplifier 25 and the emergency hydraulic circuit is 26.

FIG. 4 is an explanatory diagram of a sequence for sending hydraulic pressure to the hydraulic cylinder 4B of the pinch roll 3B, and is an explanatory diagram of a hydraulic circuit in which the regular hydraulic valve unit 27 and the emergency hydraulic valve unit 28 are combined.

The normal hydraulic valve unit 27 in the figure is a hydraulic valve unit for the pinch roll pressure hydraulic circuit used in normal times, and the emergency hydraulic valve unit 28 is an emergency hydraulic valve unit that guarantees high pressure in the pinch roll pressure hydraulic circuit in an emergency. This is a hydraulic valve unit including an accumulator 29 for.

In the regular hydraulic valve unit 27, the hydraulic pressure from the hydraulic main pipe 30 reaches the hydraulic cylinder 4B via the pressure reducing valve 31 and the directional control valve 32, and presses and releases the slab of the roll 3B.

If an abnormal drop in hydraulic pressure occurs due to an accident in the hydraulic piping system, power outage, etc., the pressure switch 33 is activated and sends a signal to the emergency hydraulic circuit 26.

In the emergency hydraulic valve unit 28, the directional control valve 34 is activated in the event of an emergency such as detection of an abnormal descending speed of the slab or occurrence of an abnormal drop in the oil pressure of the cylinder for rolling down, and the accumulator 29 operates completely independently of the regular piping system. to ensure the hydraulic pressure of the pinch roll reduction cylinder by replenishing high pressure oil.

Note that the regular hydraulic valve unit 27 and the emergency hydraulic valve unit 28 are similarly connected to other pinch roll units.

Further, as a hydraulic system for these valve units, a hydraulic return pipe 35 and a drain pipe 36 are arranged with respect to the main pipe 30.

The emergency hydraulic pressure guarantee device of the present invention includes the emergency hydraulic circuit 26, the emergency hydraulic valve unit 29, and the like.

That is, the emergency hydraulic circuit 26 receives signals from the slab speed device and the pressure switch 33 for detecting an abnormal drop in hydraulic pressure.
The emergency valve unit 28 includes a directional control valve 34, an accumulator 29, and the like, which operate in an emergency.

Hereinafter, falling slab accidents in continuous casting machines will be classified by cause, and in each case, how the falling slab falling prevention device according to the present invention operates to prevent them will be described.

First, falling slab accidents in continuous casting machines can be classified by cause as follows.

(a) The coefficient of friction between the slab and the pinch rolls decreases due to oil and fat adhesion on the dummy bar, resulting in the slab slipping and falling due to the loss of the pinch roll's ability to hold the slab.

(b) Hydraulic piping systems, especially hose breakage accidents when flexible hoses are used in the system, and flakes falling due to loss of slab holding power of the pinch rolls when oil pressure decreases due to seal leaks in backings, etc.

(c) Slabs falling due to a drop in hydraulic pressure due to a power outage in the hydraulic system.

) Pinch roll drive system, for example, pinch roll breakage,
Slabs falling due to loss of slab holding power due to breakage of universal joint, etc.

According to the present invention, for the causes (a) and (2), the slab descending speed measured by the slab speed detection roll 18 and the set pulling speed are constantly compared, and when an abnormality occurs, all pinch roll units are immediately Accidents can be prevented by switching to strong hydraulic pressure, and for the causes of (1) and (3), high-pressure oil is always stored in the accumulator 29, so the pressure switch 33, which detects abnormal pressure drops, can be activated. Accidents can be prevented by placing all pinch roll units under strong hydraulic pressure.

In other words, the present invention has the effect of being able to respond extremely quickly and effectively take preventive measures against all cases of falling slabs or dummy bars.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional slab pulling device, and FIGS. 2, 3, and 4 are partial explanatory views of a slab fall prevention device according to the present invention. Of these, FIG. 2 is a cross-sectional view of a roll unit for detecting slab speed of the present invention, FIG. 3 is an explanatory diagram of a slab speed detecting device, and FIG. 4 is an explanatory diagram of a hydraulic circuit including an emergency hydraulic valve. 1... Slab, 2... Guide roll, 3
,3A. 3B, 3C, 3D, 3E, 3F...Pinch roll, 4.4A, 4B, 4C, 4D, 4E, 4F...
... Hydraulic cylinder, 5 ... Cutting machine, 8 ...
... Carrier bag, 18 ... Speed detection roll, 19 ... Hydraulic cylinder for speed detection roll, 20 ... Speed setting device, 26 ...・Emergency hydraulic circuit, 27... Regular hydraulic valve unit, 28... Emergency hydraulic valve unit, 29
...Accumulator, 33...Pressure switch, 34...Directional control valve.

Claims (1)

[Claims] 1. A slab or dummy bar drawing device of a continuous casting machine that solidifies and forms molten metal, including a speed detection roll unit that measures the falling velocity of the slab independently of the drive system of the slab pulling device. If the detection device and the measured value of the detection device abnormally exceed the preset drawing speed, or if an abnormal pressure drop occurs in the pinch roll reduction hydraulic circuit of the slab drawing device, the emergency hydraulic circuit will A slab fall prevention device for a continuous casting machine, characterized in that it includes an emergency hydraulic pressure guarantee device that guarantees the hydraulic pressure of a hydraulic circuit for pinch roll reduction.