JPH05212414A - Method for controlling prevention of slab buckling and hydraulic circuit used therefor - Google Patents

Abstract

PURPOSE:To reduce the carrier resistance of slab, move the slab with high responsiveness when the slab moves from a rolling reduction course in the width direction (a pressure accumulating course) to the carrier copying course of the slab and compensate the dead weight of a roll for preventing buckling to the carrier resistance when the slab is carried. CONSTITUTION:In a hydraulic circuit for preventing the slab buckling to operate a buckling preventing roll 11 through a double rod type cylinder 14 mounted on a press to compress the slab 10 in the width direction, a primary side pressure oil tube path 20 connecting with the primary side of the cylinder 14 and a secondary side pressure oil tube path 30 connecting with the secondary side of the cylinder 14 are made up independently. On the primary side pressure oil tube path, a 1st proportional control valve 22, a high pressure accumulator 23, a switching electromagnetic valve 25 and a reducing valve 26 are connected in sequence with the primary side and on the secondary side pressure oil tube path, a secondary proportional control valve 33 and a low pressure accumulator 32 are connected in sequence with the secondary side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for preventing buckling due to compression in the width direction of a slab in a hot rolling process and a hydraulic circuit used for the control method.

[0002]

2. Description of the Related Art When a strip is manufactured from a slab material in a hot rolling step, there is a step of strongly reducing the slab in a width direction by a width press.

In this width press, a so-called buckling phenomenon appears as the pressure is reduced, and it becomes difficult to adjust the width. This phenomenon may be caused by maintaining the parallelism between the end surface of the slab material and the press die, or by the slab shape, but basically it is always necessary to ensure that the amount of reduction, slab thickness, and rigidity in the slab width direction are constant. This is a phenomenon that occurs.

FIG. 9 shows an example of this phenomenon. The width of the wide slab is 1600 mm and the thickness is 270 mm. When the reduction amount of 350 mm is applied, the slab buckling is gradually promoted. In order to prevent this phenomenon, it has been conventionally proposed to install a pressing roller (roller for preventing buckling) to strengthen the restraint of the upper and lower surfaces of the slab.

For example, Japanese Patent Laid-Open No. 63-72444 discloses that
In the hydraulic circuit for the buckling prevention return cylinder, 2
A configuration is disclosed in which a position 4-direction hydraulic pressure switching valve, a high pressure accumulator and a low pressure accumulator, and both accumulators are connected via a pressure reducing valve. In this case, the hydraulic circuit is provided with a high pressure accumulator on the primary side (pressure reduction side) and a low pressure accumulator on the secondary side (exhaust oil side) to form a closed loop via a pressure reducing valve.

[0006]

In order to exert the effectiveness of the control in the above width press, it is necessary to always restrain the vertical direction when a compressive load is applied in the width reduction direction. However, the restraint in the longitudinal direction causes slab conveyance resistance. Therefore, conventionally, it is possible to raise the buckling prevention roller so as to separate it from the slab surface except when the width direction is reduced, but when re-compacting, there is a defect that an indentation of the buckling prevention roller is formed on the slab surface.

Further, if the buckling prevention roller is pressed against the slab in the slab conveyance step, the frictional force between the slab material and the buckling prevention roller is large, and a large force is required to convey the slab material. Powerful, for example, Japanese Patent Laid-Open No. 2-25
The transport device described in Japanese Patent No. 512 is required, and the problem of slab indentation due to the strong pinch force of this transport device or shortening of the pinch roller life due to contact with a high temperature slab, and heat removal of the slab from the pinch roller, etc. There is.

On the other hand, in the hydraulic circuit described in the above publication, the high pressure accumulator and the low pressure accumulator are provided in the closed loop.
The purpose is to reduce pressure fluctuations as much as possible, but from a practical viewpoint, it is sufficient for the high-pressure accumulator to have a function of suppressing an excessive rise in pressure.

On the contrary, by focusing on the pressure fluctuation,
During the transition from the width direction rolling process (accumulation process) to the slab transfer copying process, it cannot be instantaneously moved, and the pressing roller is still rolling down the slab surface with a considerable rolling force. The transport resistance of is considerably large.

Further, since the high pressure and low pressure accumulators are provided in one hydraulic loop, it is not possible to arbitrarily select the base pressure setting in the width direction pressure reduction process (pressure accumulation process). further,
The self-weight of the buckling prevention roller cannot be compensated for the conveyance resistance during slab conveyance, and as a result, the conveyance resistance must be relatively large.

Therefore, the main problems of the present invention are to reduce the conveyance resistance of the slab, to enable the transition in the width direction rolling process (pressure accumulation process) to the slab conveyance copying process with high responsiveness, It is to be able to compensate for the own weight of the buckling prevention roller with respect to the conveyance resistance during conveyance.

[0012]

SUMMARY OF THE INVENTION The above-mentioned problem is to prevent slab buckling by operating a buckling prevention roller by a double rod type cylinder provided in a press for compressing a slab in a width direction as a hydraulic circuit configuration. In the hydraulic circuit, a primary side pressure oil pipeline connected to the primary side of the cylinder and a secondary side pressure oil pipeline connected to the secondary side of the cylinder are independently configured, and in the primary side pressure oil pipeline, Proportional control valve, high pressure accumulator, switching solenoid valve and pressure reducing valve
Is connected to the secondary side, and in the secondary side pressure oil pipe line, the second
This can be solved by sequentially connecting the proportional control valve and the low pressure accumulator to the secondary side.

As a control method, in a slab buckling prevention hydraulic circuit in which a buckling prevention roller is operated by a double rod type cylinder provided in a press for compressing a slab in the width direction, a primary side of the cylinder is used. The primary side pressure oil pipeline and the secondary side pressure oil pipeline connected to the secondary side of the cylinder are independently configured, and in the primary side pressure oil pipeline, a first proportional control valve, a high pressure accumulator, and A switching solenoid valve and a pressure reducing valve are sequentially connected to the primary side, and in the secondary side pressure oil pipe, a second proportional control valve and a low pressure accumulator are sequentially connected to the secondary side. Utilizing a hydraulic circuit for prevention: the roller is made to stand by at a predetermined height position below the height level of the thickness increase of the slab, and the height of the slab is increased during the pressure accumulation process from the start to the end of the width reduction of the slab. Level In response to the increase, the first proportional control valve is operated to linearly raise the height position of the roller while continuing the reduction. At the end of this reduction, the pressure reducing valve is immediately operated to reduce the primary side hydraulic pressure. After separating from the surface of the slab, keep the pressure of the primary side and the pressure oil of the secondary side with time while keeping the pressure low, and continue the reduction with a substantially constant load while following the shape of the slab surface. Can be solved with.

[0014]

In the present invention, the primary side pressure oil pipeline connected to the primary side of the cylinder and the secondary side pressure oil pipeline connected to the secondary side of the cylinder are independently configured, and the primary side pressure oil pipeline is A first proportional control valve, a high pressure accumulator, a switching solenoid valve,
A pressure reducing valve is sequentially connected to the primary side, and a second proportional control valve and a low pressure accumulator are sequentially connected to the secondary side pressure oil pipe.
Since it is connected to the secondary side, during the transition from the width direction rolling process (pressure accumulating process) to the slab transfer copying process, the pressure reducing valve can be operated to make an instantaneous transfer, and the transfer resistance of the slab can be reduced. it can. In addition, it is possible to make a transition with high responsiveness during the transition from the width direction rolling process (pressure accumulating process) to the slab conveyance copying process.
Further, by properly selecting the set values of the first proportional control valve and the second proportional control valve, the self-weight of the buckling prevention roller can be compensated for the conveyance resistance during the slab conveyance.

[0015]

EXAMPLES Next, the present invention will be specifically described by way of examples. FIG. 1 shows a buckling prevention press machine 1 according to the present invention and a hydraulic circuit for its operation, and FIG. 2 shows a width shrinkage press machine 2 and a conveyance facility.

Reference numeral 10 denotes a slab, which is pressing rollers 11 and 12 for controlling the upper and lower surfaces thereof, and particularly the upper pressing roller 11 constitutes the buckling prevention roller of the present invention. The pressing roller 11 is the frame 13 of the buckling prevention press 1.
It is designed to be moved up and down by a double rod type cylinder (returning cylinder) 14 having one end fixed to it.

On the other hand, the width-shrinking press 2 is driven by its driving main motor 15 through a pair of transmission mechanisms 16 and 16 and piston crank mechanisms 17 and 17 and dies 18 and 1.
8 presses both end surfaces of the slab 10. Further, in order to press the slab 10 while it is being conveyed, die slide mechanisms 19 and 19 are provided to move the dies 18 in the conveying direction in synchronization with the conveying speed. The mold slide mechanism 19 is a drive motor 19A,
The piston crank mechanism 19B is included, and the die 18 is configured to move in the carrying direction while being held. Reference numeral 3 is an entrance side conveyance table, and 4 is an exit side conveyance table.

In the present invention, the hydraulic circuit shown in FIG. 1 is provided in order to prevent the above-described width compression press 2 from buckling in the vertical direction due to the width compression of the slab. That is, the primary side pressure oil pipe line 20 connected to the primary side (pressing side) of the cylinder 14 and the secondary side pressure oil pipe line 30 connected to the secondary side (drain oil side) of the cylinder 14 are independently configured. In the side pressure oil pipe line 20, the hydraulic pressure from the hydraulic pump 21 causes the first proportional control valve 22, the parallel high pressure accumulators 23, 23,
A switching valve 24, a switching solenoid valve 25, and a pressure reducing valve 26 are sequentially connected to the primary side of the cylinder 14.

On the other hand, in the secondary side pressure oil line 30,
The hydraulic pump 31, the second proportional control valve 33, and the parallel low-pressure accumulators 32, 32 are sequentially connected to the secondary side.

A position detector 40 of the upper pressing roller 11 made of a "Magnescale" or the like is provided between the holding head of the upper pressing roller 11 and the frame 13 in parallel with the cylinder 14, and a position detection signal from the position detector 40 is provided. Used as a control signal. Reference numeral 41 is a drive cylinder for the lower pressing roller 12, and 42 is a position detector thereof, which is configured to perform the same operation with respect to the cylinder 41. Two drive cylinders are arranged in series with respect to the lower pressing roller 12 in order to lengthen the stroke in order to cope with an emergency. Similarly, the drive cylinders 41, 41 are connected to the high pressure oil line on the primary side and the low pressure oil line on the secondary side, but not shown.

Under the hydraulic circuit thus constructed, the following operation is performed. That is, the upper pressing roller 1
The position setting schedule of No. 4 will be described with reference to FIG. (Initial pressing position control: APC) First, the slab 10
The upper pressing roller 11 which is separated upward with respect to
Based on the position signal from the position detector 40, the slab 1 is adjusted in accordance with the initial thickness and width shrinkage of the slab.
It is lowered to a predetermined position by δ from the increased thickness of 0 (the assumed upper surface level after the increased thickness) and stands by at that position.

(Accumulation control during width contraction process: ACC) When the width compression of the slab described above is started, the opening of the first proportional control valve 22 which is closed 100% in advance is reduced in the width direction of the slab. During the pressure accumulation process from the start to the end, the slab 1 is automatically opened in sequence as the height level of the slab increases.
While continuing the reduction with respect to 0, the height position of the upper pressing roller 11 is linearly raised. In this case, switching valve 2
4 is at the position shown, the switching solenoid valve 25 is at the pressure oil side 25a, and the pressure reducing valve 26 is at the closed position 26b. Therefore, the upper pressing roller 11 relatively presses the upper surface of the slab 10 with a pressing force that prevents buckling due to the thickening of the slab 10. Further, excessive pressure is absorbed and prevented by the high pressure accumulator 23. Further, the base pressure in this pressure accumulation control can be appropriately set in advance by the first proportional control valve 22.

(Pressure reduction control: RP) At the end of this pressure accumulation for buckling prevention, the pressure reduction valve 26 is immediately operated to switch to the pressure reduction position 26a. As a result, the primary hydraulic circuit 20 is quickly depressurized, and the upper pressing roller 11
Are spaced from the slab 10 surface. Further, due to the set values of the first proportional control valve 22 and the second proportional control valve 33, in other words, due to the balance between the high pressure side and the low pressure side, as shown in FIG. Mode (I), mode of maintaining contact with a momentarily substantially weak force (II), mode of relatively slowly and gradually contacting with weak force (III), etc. Can be taken. Both of these have much lower transport resistance than those disclosed in JP-A-63-72444.

(Low-pressure control CPR during slab transfer) Thus, when the primary hydraulic circuit 20 is in a low-pressure state, 2
When the hydraulic pressure is applied to the secondary hydraulic circuit 30, the molds 18, 18 are separated from both side surfaces of the slab 10 whose width has been compressed, and conveyance is started. At this time, the upper pressing roller 11 presses with a low pressure corresponding to the difference between the base set pressures of the first proportional control valve 21 and the second proportional control valve 33 in advance. That is, while keeping the primary-side hydraulic pressure and the secondary-side hydraulic pressure in balance with time, the upper pressing roller 11 is made to follow the slab surface shape and the reduction is continued with a substantially constant load. In this case, in the process of passing through the thickened portion, as shown in FIG. 3, the upper pressing roller 11 moves downward and the light reduction is continued.

According to the structure of this embodiment, the buckling prevention roller 11 can be pressed against the slab 10 with a comparatively large pressing force to prevent the buckling, or the contact can be switched to the light contact at the time of conveyance. The buckling prevention roller 11 can be operated while being in contact with the slab shape (slab thickness increase shape) without forcibly moving up and down. As a result, the resistance of the buckling prevention roller 11 at the time of slab conveyance is reduced, the conveyance force is small, and indentation of the buckling prevention roller 11 can be prevented. The buckling prevention roller 11 is a slab 10.
Since it moves along this surface while contacting it with a light force, the buckling prevention roller 11 does not involve any unnecessary stroke.

<Examples> Next, the effects of the present invention will be described through specific examples. Fig. 4 shows the change of the rolling load by the buckling prevention roller when the control method shown in Fig. 3 is applied while the width reduction amount of 350 mm is given by the slab material of 1600 mm width and 270 mm thickness. Therefore, it can be confirmed that the switching to the buckling prevention high pressure accumulation control (A portion in the figure) and the conveyance low pressure control (B portion in the figure) is changed according to the start and end of the reduction in the width direction.

Further, the effect of reducing the transport resistance of the slab can be evaluated by the load current of the table roller for transporting the slab, and FIGS. 6 and 7 show the inlet side transport table 3 and the outlet side transport table 4. 3 shows the change in the load current of the. It can be seen that when the upper pressing roller is in contact with the surface of the slab, the load current is around 200%, whereas the rated current flows with a light load, and the slab is transported smoothly.

Further, FIGS. 8 and 9 show the slab buckling prevention effect by this control. The amount of reduction when the slab is not pressed in the initial stage and then the slab is pressed to the tail part. And the shape profile of the slab. By applying this control from the central part of the slab longitudinal direction, it is gradually promoted from the slab head part to about 50 mm.
This is an example of suppressing the buckling amount to 0 mm in the slab tail part, which shows the occurrence of the buckling amount up to 0 mm, and shows the effectiveness of this control.

[0029]

As described above, according to the present invention, the conveyance resistance of the slab is reduced and the width direction rolling process (pressure accumulating process) is performed.
It is possible to make a transition with high responsiveness during the transition from the to slab conveyance copying process, and it is possible to compensate for the own weight of the buckling prevention roller with respect to the conveyance resistance during the slab conveyance.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a buckling prevention press machine according to the present invention and a hydraulic circuit for its operation.

FIG. 2 is a diagram showing a width-shrinking press machine and transportation equipment according to the present invention.

FIG. 3 is a diagram showing a position setting schedule of an upper pressing roller.

FIG. 4 is a diagram showing changes in a rolling load by a buckling prevention roller.

FIG. 5 is a diagram showing a change in press load by a buckling prevention roller.

FIG. 6 is a diagram showing a change in load current of the entrance side transport table.

FIG. 7 is a diagram showing a change in load current of the delivery side transport table.

FIG. 8 is a diagram showing the relationship between the slab longitudinal direction position and the amount of reduction when the present invention is applied.

FIG. 9 is a diagram showing a slab shape profile when the present invention is applied.

FIG. 10 is a diagram showing a transition process of an RP control period.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Buckling prevention press machine, 2 ... Width shrinkage press machine, 3 ... Entry side conveyance table, 4 ... Exit side conveyance table, 10 ... Slab, 11, 12 ... Pressing roller, 13 ... Frame, 14 ... Both Rod type cylinder, 15 ... Drive main motor, 16 ... Transmission mechanism, 17 ... Piston crank mechanism, 18 ... Mold, 19 ... Mold slide mechanism, 20 ... Primary pressure oil pipeline, 21 ... Hydraulic pump,
22 ... 1st proportional control valve, 23 ... High pressure accumulator, 24 ... Switching valve, 25
… Switching solenoid valve, 26… Pressure reducing valve, 30… Secondary side pressure oil pipe line, 31…
Hydraulic pump, 32 ... Low pressure accumulator, 33 ... Second proportional control valve, 40
… Position detector, 41… Cylinder.

Claims (2)

[Claims] 1. A slab buckling prevention hydraulic circuit in which a buckling prevention roller is actuated by a double rod type cylinder provided in a press for compressing a slab in the width direction, a primary connecting to a primary side of the cylinder. The side pressure oil pipeline and the secondary side pressure oil pipeline connected to the secondary side of the cylinder are independently configured, and in the primary side pressure oil pipeline, a first proportional control valve, a high pressure accumulator, and a switching solenoid valve are provided. , A pressure reducing valve are sequentially connected to the primary side, and in the secondary side pressure oil pipeline, a second proportional control valve and a low pressure accumulator are sequentially connected to the secondary side. Hydraulic circuit for bending prevention. 2. A slab buckling prevention hydraulic circuit in which a buckling prevention roller is operated by a double rod type cylinder provided in a press for compressing a slab in the width direction, a primary connecting to the primary side of the cylinder. The side pressure oil pipeline and the secondary side pressure oil pipeline connected to the secondary side of the cylinder are independently configured, and in the primary side pressure oil pipeline, a first proportional control valve, a high pressure accumulator, and a switching solenoid valve are provided. , A pressure reducing valve are sequentially connected to the primary side, and a secondary proportional control valve and a low pressure accumulator are sequentially connected to the secondary side in the secondary side pressure oil pipe line. Utilizing the: increase of the height level of the slab in the pressure accumulation process from the start of the width reduction of the slab to the end thereof by making the roller stand by at a predetermined height position below the height level of the thickness increase of the slab. Depending on the first ratio After operating the control valve to linearly raise the height position of the roller while continuing the reduction, and immediately after this reduction, operate the pressure reducing valve to reduce the primary side hydraulic pressure and separate it from the slab surface. The slab seat is characterized in that, in a low-pressure state, the primary-side pressure oil and the secondary-side pressure oil are balanced over time, and the reduction is continued with a substantially constant load while following the slab surface shape. Anti-flex control method.