JPH07214156A - Method for preventing necking and its device - Google Patents

Abstract

PURPOSE:To prevent the necking of a strip. CONSTITUTION:Pushing force of a pinch roll at an inlet side of a coiler is made to be the necessary setting value to prevent the necking at the time of starting the winding of the strip 2 onto the coiler 7. By this method, in the case of rapidly developing the tension force to the strip 2 by the speed difference between both when the strip 2 winds onto the coiler 7, the propagation of the excess tension force to the upstream side is stemmed because of increase of the pushing force of the pinch roll 6 at the inlet side of the coiler. Then, the development of the necking to a part of the soft strip 2 having high temp. just after coming out a rolling mill 1 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for preventing necking in hot rolling equipment.

[0002]

2. Description of the Related Art A side view of a hot rolling facility is shown in FIG. 4 and a plan view thereof is shown in FIG. In the hot rolling equipment as shown in FIGS. 4 and 5, the strip 2 rolled by the rolling mill 1 is conveyed to the downstream side 5 by the run-out table 3 and is cooled by the cooling device 4 on the way, and then the pinch roll. The direction is changed by 6 and is wound by the winder 7.

[0003]

However, the conventional rolling equipment described above has the following problems.

That is, in the hot rolling equipment shown in FIGS. 4 and 5, the rolling mill 1 rolls the strip 2 in order to reliably convey the strip 2 coming out of the rolling mill 1 and wind it around the winding machine 7. The speed of the runout table 3 is made faster than the speed of sending it out. Further, the speed of the pinch roll 6 is higher than that of the runout table 3 and the speed of the mandrel 9 of the winder 7 is higher than that of the pinch roll 6, and the strip 2 is guided to the winder 7 while being pulled. This is referred to as having a lead speed, and the mandrel 9 is rotating 10% faster inward and outward than the strip 2 which normally enters. The strip 2 that has entered the winder 7 jumps into the gap around the mandrel 9 formed by the trumpet roll 8 and an apron (not shown) between them, and is pressed against the mandrel 9 by the trumpet roll 8 to lead the lead. It is wound up at the speed and wound tightly on the mandrel 9.

At the moment when the strip 2 is wound around the mandrel 9, the mandrel 9 is pulled by the strip 2 and is rapidly decelerated to the speed of the strip 2. At this time, the kinetic energy corresponding to the lead speed of the mandrel 9 is applied to the strip 2
Absorbed by the elongation of. As a result, as shown in FIG. 5, in the portion having the highest temperature between the rolling mill final stand 1 and the mandrel 9, that is, in the portion 10 in front of the cooling device 4, in the width direction and the thickness direction of the strip 2. The size is reduced. This reduction in thickness and width is called necking, which impairs the quality of the strip 2 and has been a problem.

In view of the above situation, it is an object of the present invention to provide a necking prevention method and apparatus for preventing strip necking.

[0007]

According to a first aspect of the present invention, there is provided a rolling machine in a rolling facility in which a strip rolled by a rolling machine is wound by the winding machine through a pinch roll on the winding machine entrance side. A necking prevention method characterized in that the pressing force of the pinch roll on the winder input side is temporarily increased at the start of winding of the strip tip, and the pressing force is returned to the original setting value at the end of winding of the tip. It is such a thing.

According to a second aspect of the present invention, a necking prevention pinch roll is provided upstream of the winder inlet side pinch roll, and the winder inlet side pinch roll is provided at the start of winding the strip front end portion on the winder. The necking prevention device is provided with a pinch roll controller that temporarily increases the pressing force and returns the pressing force to the original set value when the winding of the tip end is completed.

[0009]

The operation of the present invention is as follows.

The strip rolled by the rolling mill is adapted to be wound by the winder through a pinch roll on the winder entrance side.

According to the first aspect of the present invention, the necking prevention control device temporarily increases the pressing force of the winder inlet side pinch roll at the start of winding the strip front end onto the winder. When the tip of the strip winds around the winder, even if a sudden pulling force is generated on the strip due to the speed difference between the two, there is a pulling force that acts on the strip by the pressing force of the winder inlet side pinch roll. It is suppressed below the value, and as a result, necking is prevented from occurring in the strip of the high temperature and soft portion immediately after leaving the rolling mill.

When the winding of the strip front end on the winder is completed, the pressing force of the winder input side pinch roll is returned to the set value required for strip winding.

According to the second aspect of the present invention, the necking prevention pinch roll whose pressing force is controlled is provided upstream of the winder input side pinch roll, so that the leading end of the strip is wound around the winder. Since the tensile force generated at the time of attachment can be further reduced, necking can be prevented more reliably.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment of the present invention. An upper pinch roll 19 and a lower pinch roll 20 are attached to an upper chock 21 and a lower chock 22 provided in a housing (not shown), respectively.
The strip 2 is sandwiched between the upper and lower pinch rolls 19 and 20, the direction thereof is changed, and the strip 2 is guided to the winder 7 and wound up.

Left and right bearings of the upper pinch roll 19
A hydraulic cylinder 18 is provided in each of the
And are each connected to the servo valve 16. Servo valve 16
Has its opening controlled by a command signal 15,
Adjust the outflow and inflow of hydraulic oil. The command signal 15 is
Made by pinch roll controller 13, upper pinch roll 19
Servo valve 1 so that the position and pressing force become the set value.
6 is a signal for controlling 6. The pinch roll controller 13
Set the pinch roll pressing force setting signal 12 from the setting device 11.
In response, a command signal to the servo valve 16 is generated,
Control device or process of higher rank as progress of group 2
Receiving a sequence signal 14 from a computer (not shown)
To change the pressing force of the pinch roll.
Also do. 23 and 24 are respectively on the head side of the hydraulic cylinder 18.
And a pressure detector that detects the pressure on the rod side, 25 is a pressure detector
Pushing force of the pinch roll 6 from the signals of the output devices 23 and 24
F _PrIs a computing unit for computing.

The operation of this embodiment is as follows.

As described with reference to FIGS. 4 and 5, the strip 2 rolled by the rolling mill 1 is conveyed to the downstream side 5 by the runout table 3 and is cooled by the cooling device 4 on the way, and then by the pinch roll 6. The direction is changed and it is wound by the winder 7.

FIG. 2 shows changes in the tension a between the mandrel 9 and the pinch roll 6 and the tension b between the pinch roll 6 and the final stand 1 of the finish rolling mill during winding. The horizontal axis represents time, and shows how the tensions a and b change with time for 3 seconds after the strip 2 jumps into the winder 7.

The strip 2 jumped into the winder 7 at time 0 is wound up for a time A by the frictional force of the trumpet roll 8 and wound around the mandrel 9 at time a. At this time, since the loop of the strip 2 is still present on the runout table 3, the tension b between the pinch roll 6 and the final stand 1 of the finishing mill does not rise. During the time B, the loop of the strip 2 is absorbed, and the tension b between the pinch roll 6 and the final stand 1 of the finishing mill rapidly rises at the time point b. At the same time, the tension a between the mandrel 9 and the pinch roll 6 also rises. At this time, pinch roll 6
And the tensile stress σ _T between the final stand 1 of the finishing mill and
When the temperature on the outlet side of the final stand 1 of the finishing rolling mill becomes higher than the yield stress σ _{y of the} highest part, necking occurs in which the dimension becomes smaller in the strip width direction and the thickness direction as described above.

From the above, in order to prevent necking, the fluctuation of the tension generated at the moment when the strip 2 is wound around the mandrel 9 is small, and the yield stress of the upstream strip 2 is small at a high temperature as compared with other portions. It turns out that it is effective to block transmission to parts.

In the apparatus of the present invention, before the strip 2 enters the winder 7, the setting device 11 is previously provided with the pinch roll pressing force setting value F _P necessary for preventing necking. Before the strip 2 passes through the pinch roll section 6,
Pinch roll pressing force setting signal 12 from the setting device 11
Is given to the pinch roll controller 13, and the command signal 15 is sent from the pinch roll controller 13 to the servo valve 16.
The servo valve 16 adjusts the inflow / outflow amount of oil to / from the hydraulic cylinder 18 via the pipe 17 according to the value of the command signal 15. The pressure in the cylinder is detected by the pressure detectors 23 and 24 provided on the head side and the rod side of the cylinder, and sent to the calculator 25. In the calculator 25, the pressing force F _Pr of the pinch roll is calculated by the following equation,

[ _Mathematical formula-see original _document ] It is calculated by F _Pr = P _H · A _H −P _R · A _R , and the signal 26 is sent to the pinch roll controller 13. The pinch roll controller 13, and the pinch roll pressing force set value F _P Former, are compared the actual pressing force F _Pr, command signal 15 to the servo valve 16 until the difference E = F _P -F _Pr disappears Given, hydraulic cylinder 18
The amount of oil flowing in and out of the oil is adjusted. When they match, the command signal 15 to the servo valve 16 becomes zero, and the inflow and outflow of oil to the hydraulic cylinder 18 is stopped. as a result,
The pressing force F _Pr of the pinch roll 6 becomes the set value F _P.

As described with reference to FIG. 2, the mandrel 9 is sprayed.
Trip 2 is wrapped around, and strikeout on runout table 3
When the loop of loop 2 is absorbed, the lead speed of mandrel 9
The kinetic energy of the degree is absorbed by the elongation of the strip 2.
It That is, the mandrel 9 is pulled on the strip 2.
It will be decelerated due to
The widthwise and thicknesswise dimensions of the flap 2 are reduced. This
At this time, the pinch roll 6 in front of the mandrel 9 strips
2 to F_PrWhen pressing with the pressing force of _Pμ = F
_Pr・ Μ (μ: Friction between pinch roll 6 and strip 2
Force) acts in the longitudinal direction of the strip 2. That
This force causes the mandrel 9 to be pulled by the strip 2.
The tension generated when the speed is reduced is reduced. Sanawa
The pinch roll 6 is F_Pμ = F_Pr・ Only for μ force
It tries to prevent the mandrel 9 from being pulled. Obey
Yield stress of the strip 2 where necking occurs
Σ_yThen, the generated tensile stress σ_TIs σ_T<Σ_yBecomes
If the tension is cut off with the pinch roll 6,
It is possible to prevent the occurrence of ruggedness. With pinch roll 6
Tensile stress σ_PIs σ_P= F_Pμ / (H ・ W) = F_Pr・
It is expressed as μ / (H · W) (H: plate thickness, W: plate
Width), σ_P≧ σ_T−σ_yFor each rolled material
The pushing force of the pinch roll 6 applied to the setter 11
available.

This pressing force is generally the pinch roll 6
Is greater than the pressing force required to pull the strip 2, in which case the sequence signal 14 is applied to the pinch roll controller 13 after the tip of the strip 2 has wrapped around the mandrel 9 and wound a few times. Then, the command signal 15 is sent from the pinch roll controller 13 to the servo valve 16, and the pressing force of the pinch roll 6 is returned to the original value required for pulling the strip 2 as described above, and the winding is performed. Will continue.

Thus, the propagation of excessive tension fluctuations to the softest portion of the strip 2 where the temperature is high and the upstream side of the mandrel 9 is blocked, so that necking is prevented.

FIG. 3 shows a second embodiment of the present invention, in which a necking prevention pinch roll 27 which operates in the same manner is provided upstream of the pinch roll 6 on the winder inlet side. The tension fluctuation generated when the mandrel 9 is wound around is cut off. By doing so, it is possible to further reduce the propagation of the generated tension fluctuation to the upstream side, so that it is possible to further enhance the necking prevention capability.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0028]

As described above, according to the necking prevention method and the apparatus thereof of the present invention, the excellent effect that the necking of the strip can be prevented can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of a first embodiment of the present invention.

FIG. 2 is a diagram showing how tension changes with time during rolling.

FIG. 3 is a schematic side view of a second embodiment of the present invention.

FIG. 4 is a schematic side view of a conventional example.

FIG. 5 is a plan view of FIG.

[Explanation of symbols]

 1 Rolling mill 2 Strip 6 Winding machine Input side pinch roll 7 Winding machine 12 Set value (pinch roll pressing force setting signal) 27 Necking prevention pinch roll

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Takayo 1 Shin-Nakahara-cho, Isogo-ku, Yokohama, Kanagawa Ishi, Kawashima Harima Heavy Industries, Ltd. Yokohama Second Factory (72) Inventor Nobuhiro Ito Chuo-ku, Chiba, Chiba Kawasaki-cho 1 Kawasaki Steel Co., Ltd. Chiba Steel Works (72) Inventor Toshio Imaseki 1 Kawasaki-cho Chuo-ku, Chiba City Chiba Prefecture Kawasaki Steel Co., Ltd. Chiba Steel Works (72) Inventor Tosada Takechi Chiba Chiba City Central 1 Kawasaki-cho, Ward Kawasaki Steel Co., Ltd. Chiba Works

Claims (2)

[Claims] 1. In a rolling facility in which a strip rolled by a rolling mill is wound by a winding machine through a pinch roll on an inlet side of the winding machine, the winding machine is started at the start of winding the strip front end on the winding machine. A necking prevention method characterized by temporarily increasing the pressing force of the entrance side pinch roll and returning the pressing force to the original set value at the end of winding the tip end. 2. A necking prevention pinch roll is provided upstream of the winder input side pinch roll, and a pressing force of the winder input side pinch roll is temporarily provided at the start of winding the strip front end portion on the winder. And a pinch roll controller for returning the pressing force to the original set value when the winding of the tip end is completed.