JPS6354442B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to an apparatus for preventing buckling during width reduction of a slab.

(Prior Art) When considering the productivity of a continuous casting machine, it is desirable to continuously cast the same width. In recent years, it has become possible to change the running width of continuous casting machines, and it has become possible to produce slabs of various widths for downstream processes, such as hot strip mills. The amount of width change is small, about 50mm.
In addition, the slab has a tapered width in the longitudinal direction of the slab.

Currently, in hot strip mills, the width of the slab needs to correspond almost one-to-one to the width of the rolled product, which reduces the production efficiency of the continuous casting machine and makes it difficult to match production with the hot strip mill. This resulted in problems such as the inability to raise the temperature at which the slab was charged into the heating furnace.

Therefore, as a countermeasure, the idea that the slab width of the continuous casting machine would be constant was created by increasing the amount of width change in the hot strip mill.
This type of operation has come to be called hot large reduction.

When large reductions are carried out, the problem is that the required width reduction cannot be achieved due to buckling of the slab, and measures to prevent buckling have become an important issue.

(Problems to be Solved by the Invention) In order to prevent buckling, it is possible to press down the center of the slab width, but if a large reduction is performed, the thickness of the center of the slab width will also increase, so in this case, It is displaced as shown by the broken line in FIG. Therefore,
It is necessary to distinguish between the displacement at the time of buckling and the broken line shown in FIG.

Since the distortion shown in Figures 4 and 5 occurs in the vicinity of the width reduction tool, the temperature is high, and it is difficult to install a detector due to the influence of water vapor and space issues on the equipment. There is a need for a device that can operate automatically.

"Structure of the Invention" (Means for Solving Problems) The present invention provides an apparatus for reducing the width of a slab, which includes a roller that presses the slab symmetrically up and down with a cylinder located at the center of the width direction of the slab; The hydraulic circuit of the cylinder has two 3-position main directional switching valves each having a block port for operating the cylinder, and when the main directional switching valve is located at the block port, it opens to the pressure side chamber of the cylinder and drains the working fluid. and a switching valve that replenishes the pressure, and opens only when the pressure in the pressure side chambers of both cylinders reaches a pressure set higher than the pressure supplied to the inlet side of the main directional switching valve to release the working fluid in the pressure side chamber. It is equipped with a valve.

(Embodiment) An embodiment of the present invention will be described in detail based on FIGS. 1 to 3. As shown in FIGS. 2 and 3, cylinders 2,
2', and the piston rods 3, 3' are provided with rollers 5, 5' that contact the slab 4, respectively, and a rolling cylinder 7 that moves anvils 6, 6' for rolling down the slab 4 on both sides of the press housing 1. , 7' are provided to form a large reduction facility.

Both cylinders 2, 2' have pressure side chambers 2A, 2A' connected to main directional switching valves 9, 9' formed by 4-port, 3-position switching valves via piping 8, 8', respectively, and rod side chambers 2B, 2B'. are connected to the main directional control valves 9, 9' via pipes 10, 10'. and,
The main directional control valves 9 and 9' are connected to the pump P by piping 11 and
11', it is connected to the tank T with piping 12, 12'.

Further, both pipes 8, which are continuous to the cylinders 2 and 2',
10, 8' and 10' are check valves 13 and 13', respectively.
and the pilot check valves 14, 14' in series.

Also, one pipe 8 is connected to the other check valve 13' via a check valve 16 by a pilot pipe 15.
The other pipe 8' is also connected to the other check valve 13 via a check valve 16' by a pilot pipe 15'. Both check valves 16, 16' are connected to the other pilot piping 15,
15', respectively.

Also, the pipes 11, 11' on the pump P side are the pipes 17,
The check valve 13,
13', and the piping 20 on the tank T side.
20 is connected between the check valves 13, 13' and the pilot check valves 14, 14'.

(Function) This embodiment is constructed as described above, and when first operating the cylinders 2 and 2' in the directions 5a and 5a' to press the slug 4, the main directional control valves 9 and 9' are turned on, respectively. Move in the direction of arrows 9a and 9a',
The pipes 11 and 11' on the pump P side are connected to the pipes 8 and 8, respectively.
8' and press side chamber 2A of cylinder 2, 2'.
Introduce hydraulic oil to 2A'. The hydraulic oil in the rod side chambers 2B, 2B' of the cylinders 2, 2' is contained in the pipes 10, 1.
2 and 10', 12' to the tank T, the rollers 5, 5' move in the directions of arrows 5a, 5a', respectively, and press the slab 4. After pressing the slab 4, the main directional control valves 9, 9' are returned to the block ports as shown in the figure. When the main direction switching valves 9, 9' are located at the block ports, the switching valves 18, 18' move in the directions of arrows 18b, 18b' as shown in the figure, and supply hydraulic oil to the cylinders via the check valves 19, 19'. , 2, 2' press side chambers 2A, 2
It is now possible to supply A′.

In the above state, for example, if buckling occurs upward, the pressure of the hydraulic oil in the pressure side chamber 2A of the cylinder 2 will rise, but it will be contained by the check valves 19 and 13, and the roller 5 will not rise. . Therefore, the buckling will not grow any further.

The cracking pressures of the check valves 13, 13' and 16, 16' are set higher than the pressure of the hydraulic oil supplied to the inlet sides of the main directional control valves 9, 9'.
Also, the cracking pressure of the pilot check valves 14, 14' is equivalent to the force that can raise and lower the rollers 5, 5'.
Set the pressure above B′.

As mentioned above, if buckling occurs in the upward direction,
The oil pressure in the pressure side chamber 2A of the upper cylinder 2 rises, and the pressure in the pilot pipe 15 also rises at the same time, reaching the set pressure of the check valves 13, 13' and 16, 16'. Since no force is applied, the oil pressure in the pressure side chamber 2A' of the cylinder 2' does not increase (the pressure remains the same as that supplied by the switching valve 18'). Therefore, the pressure in the pilot pipe 15' does not reach the set pressure. In this state, the check valve 16' is kept open by the pressure in the pilot pipe 15, but since the pressure in the pilot pipe 15' is below the set pressure, the check valves 13, 16 and 13' remain closed. Also, since the hydraulic oil in the rod side chambers 2B, 2B' of the cylinders 2, 2' is not pressurized, the pilot check valve 1
4 and 14 are also in a closed state. Therefore, even if buckling occurs in either the up or down direction, Check 1
3 and 13' do not open, so buckling can be prevented without growth.

Next, a case will be described in which the thickness of the slab 4 increases due to a large reduction. Due to the increased thickness, the upper and lower rollers 5, 5' are pushed in the direction of arrows 5b, 5b',
The hydraulic fluid pressures in the pressure side chambers 2A, 2A' of the upper and lower cylinders 2, 2' both rise. Therefore, the hydraulic pressure in the pressure side chambers 2A, 2A' of both cylinders 2, 2' is transmitted to the pilot pipes 15, 15' and led to the check valves 16, 16' on the opposite side, so that the pressure is lower than the cracking pressure. When the pressure rises, the respective check valves 16, 16' are released and the check valves 13, 13' are also opened, and the hydraulic oil flows into the pipes 20, 2.
0' and returns to tank T. Therefore, both rollers 5 and 5' can escape from each other toward the arrows 5b and 5b'. However, when both rollers 5, 5' move toward the arrows 5b, 5b', the rod side chambers 2B, 2
Since the inside of B' becomes negative pressure, a part of the hydraulic oil that returns to tank T passes through pilot check valves 14, 14' and piping 10, 10' to rod side chambers 2B, 2.
flows into B′.

Next, if the amount of thickness increase is different in the longitudinal direction of the slab 4 and the gap of the rollers 5, 5' that are once opened is to be made smaller, the pressing side chambers 2A of the cylinder 2,
Since the pressure inside 2A' is low, the hydraulic oil is led to the pressure side chambers 2A, 2A' through the pipes 17, 17', the switching valves 18, 18', and the check valves 19, 19', and the hydraulic oil is led to the pressure side chambers 2A, 2A', and the rollers 5, 5. ' tries to move in the direction of arrows 5a, 5a'. Then, Rod concubine room 2B, 2
The pressure in B' increases and pilot check valve 1
4, 14' and return the hydraulic oil to the tank T through the pipes 20, 20', arrows 5a, 5
The rollers 5 and 5' can each be moved to a'.

One slab 4 is then passed and in preparation for the next slab the rollers 5, 5' are moved by the arrows 5b and 5b.
When moving it in the direction 5b' to open it, move the main directional switching valves 9, 9' to the arrow 9b, 9b' side, introduce hydraulic oil into the rod side chambers 2B, 2B',
By returning the hydraulic oil in the pressure side chambers 2A, 2A' to the tank T, the rollers 5, 5' move in the directions of arrows 5b, 5b', respectively.

As is clear from the above description, both cylinders 2,
Only when the indoor pressures of the pressure side chambers 2A and 2A' of 2' rise at the same time (increasing the thickness of the slab) are the rollers 5,
5' can escape up and down.

Although not shown in FIG. 1, a constant flow valve that acts in the direction of releasing the hydraulic oil is installed near the connection between the cylinders 2, 2' and the piping 8, 8' on the pressure chamber side. If the flow rates of the pipes 8 and 8' are made equal, if large buckling occurs at the same time as the thickness of the central portion of the slab 4 increases, it is possible to cope with the increase in thickness while preventing the growth of buckling.

In the above explanation, check valves 13, 13' and 1
6, 16' to control the pressure in the pressure side chambers 2A, 2A' of both cylinders 2, 2' to the pilot piping 15, 1.
5', the check valves 13 and 13' are simultaneously opened by utilizing the pressure increase on the opposite sides, but this is also done when the respective pipes 8 and 13' are opened simultaneously.
Attach a pressure switch to 8' and check valve 13,
13', a switching valve similar to switching valves 18 and 18' is used, and the switching valve is opened only when both pressure switches reach the set pressure, and the pressure side chamber 2A of both cylinders 2 and 2' is opened. , 2A' can be released to obtain the same effect.

It should be noted that the present invention can obtain similar effects when the width of the slab is adjusted not only by a press but also by an edger equipped with vertical rolls.

"Effects of the Invention" Since the present invention has the above-described structure and operation, when the slab is significantly reduced by pressurization, it automatically follows the increase in thickness at the central part in the width direction of the slab, and only buckling can be reliably prevented. This allows pressurization work to be carried out efficiently.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram of an embodiment of the buckling prevention device during slab width reduction according to the present invention, FIG. 2 is a plan view of the width reduction device, and FIG. 3 is a longitudinal sectional view of FIG. 2. FIG. 4 is a side view showing the slab when the thickness is increased, and FIG. 5 is a side view showing the slab when buckled. In the figure, 2 and 2' are cylinders, 2A and 2A' are pressure side chambers, 2B and 2B' are rod side chambers, and 4 is a slab.
5, 5' are rollers, 9, 9' are main directional control valves, 1
8 and 18' are switching valves.

Claims (1)

[Claims] 1. A device for reducing the width of a slab, which has a roller that presses the slab with vertically symmetrical cylinders located at the center of the slab in the width direction, and a three-position roller that has a block port for operating the cylinder in the hydraulic circuit of both cylinders. Two main directional switching valves, a switching valve that opens to the pressure side chamber of the cylinder to supply working fluid when the main directional switching valve is located at the block port, and a switching valve that switches the pressure in the pressure side chamber of both cylinders in the main direction. Buckling during width reduction of a slab, characterized in that it is provided with a valve that opens to release the working fluid in the pressing side chamber only when a pressure set higher than the pressure supplied to the inlet side of the valve is reached. Prevention device.