Control method of hydraulic pinch roll and control unit thereof

Details Control method of hydraulic pinch roll and control unit thereof Control method of hydraulic pinch roll and control unit thereof

2001-08-17

2003-08-12

Matecki, Kathy (Department: 3654)

Advancing material of indeterminate length

By orbitally traveling material-engaging surface

With control or adjustment means

C226S021000, C226S187000, C072S009300, C072S011900

Reexamination Certificate

active

06604663

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of improving a winding shape of a coil to be wound by a down coiler by hydraulic pinch rolls controlled by a hydraulic cylinder and a servo valve and to a control unit thereof.
2. Description of the Related Art
FIG. 1
shows pinch rolls
1
, including upper pinch roll
1
a
and lower pinch roll
1
b
, of a down coiler
2
of hot rolling equipment being a subject of the present invention. In the hot rolling equipment, a strip
4
that has been rolled to a predetermined plate thickness by a finishing mill
3
is rolled by the down coiler to be an end item in a coil state. The pinch rolls
1
a
,
1
b
function to guide a strip
4
run on a table roller
5
to the down coiler
2
.
Recently, as shown in
FIG. 2
, a hydraulic pinch roll that controls the position of upper and lower pinch rolls and a pressing force to the strip by a hydraulic cylinder
6
and a servo valve
7
has been commercialized. Function required to such pinch rolls
1
is stretching the strip
4
to guide to the down coiler
2
in an initial period of the winding and stretching the strip
4
in an opposite direction to maintain an appropriate tension with a mandrel
2
e
after the strip
4
has been wound to the mandrel
2
e
. Accordingly, an appropriate force is given to the pinch rolls
1
to press the strip
4
.
The hydraulic pinch rolls
1
shown in
FIG. 2
is constituted as follows. Specifically, right/left chucks
1
c
and
1
d
of an upper pinch roll
1
a
is supported by the hydraulic cylinder
6
and control of excurrent/incurrent of oil to the hydraulic cylinder
6
is performed by the servo valve
7
connected via piping
8
a
and
8
b
. Pressure detector
9
a
and
9
b
are severally connected to the piping
8
a
and
8
b
so that the pressure of the hydraulic cylinder
6
at a head side
6
a
and a rod side
6
b
can be detected. Moreover, position detectors
10
c
and
10
d
can detect the position of a piston
6
c
of the hydraulic cylinder
6
.
In the hydraulic pinch rolls
1
, an initial gap is set by detecting the position of the piston
6
c
of the hydraulic cylinder
6
by the position detectors
10
c
and
10
d
and by controlling the position of the upper pinch roll
1
a
based on the signal of the detection. After the strip
4
bounces into the pinch rolls
1
to be guided to the down coiler
2
, a positional control is switched to a pressing force control in an appropriate timing, and a pressing force arithmetical unit
11
calculates the pressing force to the strip
4
of the upper pinch roll
1
a
based on the pressure of the head and rod sides
6
a
and
6
b
, which has been detected by the pressure detectors
9
a
and
9
b
, and then a servo controller
12
sends an instruction to a servo valve
7
based on the signal of the calculation to control the pressing force.
In a conventional down coiler
2
, a defective winding shape of the coil (a telescope), as shown in
FIG. 3
, has occurred due to reasons such as the case where a plane shape of the strip
4
to be wound is bad and where the strip
4
enters the pinch rolls
1
in an off-center manner. Furthermore, recently, when a wide and hard material is wound, a problem of multiple defective winding shapes as shown in
FIG. 4
in which an end surface of a wound coil has an iterative unevenness.
SUMMARY OF THE INVENTION
In consideration of the foregoing circumstances, the object of the present invention is to provide a control method of the hydraulic pinch rolls that can suppress the defective winding shape and a control unit thereof.
The inventor of the present invention has found out that the right/left difference of a piston position of the hydraulic pinch rolls, that is, the output difference of the position detectors
10
c
and
10
d
shows a periodic fluctuation when the defective winding shape occurs where the end surface of the wound coil has an iterative unevenness, and that the output difference does not show the periodic fluctuation when the defective winding shape does not occur.
Accordingly, in a first embodiment of the present invention, the control unit of the hydraulic pinch rolls is constituted such that the pressing force of the right and the left of the pinch rolls is changed moment by moment in accordance with the output difference of the position detectors
10
c
and
10
d
and the fluctuation shown in the output difference of the position detectors
10
c
and
10
d
can be suppressed. As a result, a gap fluctuation that occurs alternately in right and left (a seesaw state) on the upper pinch roll
1
a
of the hydraulic pinch rolls
1
can be prevented.
In a second embodiment of the present invention, since the control unit of the hydraulic pinch rolls
1
changes the gaps of the right and left of the pinch rolls by positional control moment by moment in accordance with the pressing force of the pinch rolls obtained from the output of the pressure detectors
9
a
and
9
b
, the gap of the pinch rolls is maintained parallelly. Accordingly, the gap fluctuation that occurs alternately in right and left on the upper pinch roll
1
a
can be prevented. As a result, the defective winding shape where the end surface of a wound coil iterates the periodical unevenness can be prevented.
Other objects and advantageous characteristic of the present invention will be made clear by the following description with reference to the accompanied drawings.


REFERENCES:
patent: 4759205 (1988-07-01), Kuwano et al.
patent: 5231858 (1993-08-01), Yamashita et al.
patent: 5868296 (1999-02-01), Gentile et al.
patent: 6185971 (2001-02-01), Kuwano et al.
patent: 6301946 (2001-10-01), Kukizaki et al.
patent: 1 016 471 (2000-07-01), None
patent: 8-52514 (1996-02-01), None
patent: 9-267126 (1997-10-01), None
Patent Abstracts of Japan, vol. 1998, No. 2, Jan. 30, 1998 & JP 09 267126 A (Kawasaki Steel Corp.), Oct. 14, 1997.
Patent Abstracts of Japan, vol. 1996, No. 06, Jun. 28, 1996 & JP 08 052514 A (Ishikawajima Harima Heavy Industries Co. Ltd.; others: 01), Feb. 27, 1996.
Patent Abstracts of Japan, vol. 1995, No. 11, Dec. 26, 1995 & JP 07 214156 A (Ishikawajima Harima Heavy Industries Co. Ltd.; others: 01), Aug. 15, 1995.

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