JP2021099142A - Fluid selector valve - Google Patents

Abstract

To provide a fluid selector valve that allows a user to readily check a failure in a fluid selector valve by allowing a user to check a stop position of a spool.SOLUTION: A fluid selector valve 1 for switching a flowing direction of fluid includes: a frame 2 provided with a cavity inside thereof; a spool 3 provided inside the cavity of the frame 2 so as to be movable in a uniaxial direction to switch a flowing direction of fluid in accordance with a stop position; and a rod 6 fixed to the spool 3 and projecting outside of the frame 2 on at least one end side in the uniaxial direction of the frame 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fluid switching valve.

In the hot rolling process of a steel mill, a winding process is performed in which a rolled steel strip (also referred to as a “strip”) is wound into a coil. In this winding process, a hot-rolled coiler (also referred to as a "winding device") having a mandrel that winds the steel strip on the surface and a plurality of wrapper rolls arranged around the mandrel is used to wind the steel strip. Winding is done. The wrapper roll is provided so as to be movable with respect to the mandrel, and the purpose is to guide the tip of the steel strip around the mandrel and to generate a frictional force between the steel strip and the mandrel by pressing the steel strip against the mandrel. Used.

This movement operation of the wrapper roll (also referred to as "opening / closing operation") is performed by operating a high-pressure air cylinder (opening operation, closing operation or neutral operation). The high-pressure air cylinder that operates the wrapper roll is operated by the fluid switching valve. A fluid switching valve is an air supplied to an air cylinder by a spool (also referred to as a "shuttle rod" or "piston") provided inside a frame (also referred to as a "housing") operated by hydraulic or pneumatic pressure. The operation of the air cylinder is controlled by changing the flow direction of the air cylinder (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-60982

By the way, in the hot-rolled coiler, due to various factors such as a defect of the fluid switching valve and a defect of the air cylinder, the opening / closing operation of the wrapper roll may not be performed normally, resulting in an opening / closing failure. In such cases, measures such as changing the unit of the hot-rolled coiler and rapid shutdown are being taken, affecting production. Among the factors that cause the wrapper roll to open and close poorly, a defective fluid switching valve occurs because the spool is not stopped at a normal position due to sticking of the spool or leakage of fluid. However, in the conventional fluid switching valve, since the spool is housed inside the metal frame, the position of the spool cannot be confirmed, and it is difficult to identify the defect of the fluid switching valve. It was. Furthermore, since it is difficult to immediately identify other factors such as defective air cylinders, if the wrapper roll fails to open or close, regardless of whether the fluid switching valve is defective or not. First of all, measures have been taken to replace the fluid switching valve.

When replacing the fluid switching valve, the work takes about 3 hours, and the influence on the production is large during that time. Further, if the cause of the opening / closing failure is other than the failure of the fluid switching valve, the time required for recovery will be further increased.
Therefore, the present invention has been made by paying attention to the above-mentioned problems, and provides a fluid switching valve capable of easily confirming a defect of the fluid switching valve by making it possible to confirm the stop position of the spool. The purpose is to do.

According to one aspect of the present invention, it is a fluid switching valve that switches the fluid flow direction, and is provided in a frame provided with a cavity inside and in the cavity of the frame so as to be movable in the uniaxial direction, and a stop position. A spool that switches the flow direction of the fluid according to the above, and a rod that is integrally configured with the spool and is provided so as to project to the outside of the frame at least on one end side in the uniaxial direction of the frame. A fluid switching valve is provided.

According to one aspect of the present invention, by making it possible to confirm the stop position of the spool, a fluid switching valve capable of easily confirming a defect of the fluid switching valve is provided.

It is sectional drawing which shows the fluid switching valve which concerns on one Embodiment of this invention. It is a schematic diagram which shows the hot-rolled coiler. It is explanatory drawing which shows the operation of the fluid switching valve which concerns on one Embodiment of this invention. It is sectional drawing which shows the conventional fluid switching valve. It is explanatory drawing which shows the operation of the conventional fluid switching valve.

The following detailed description illustrates many specific details by exemplifying embodiments of the invention to provide a complete understanding of the invention. However, it will be clear that one or more embodiments can be implemented without the description of such particular details. Also, for the sake of brevity, the drawings are schematic representations of well-known structures and devices.

<Fluid switching valve configuration>
The configuration of the fluid switching valve 1 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. The fluid switching valve 1 is provided in the hot-rolled coiler 8 shown in FIG.
The hot-rolled coiler 8 is a device for winding a hot-rolled steel strip 9 into a coil, and includes a pinch roll 80, a mandrel 81, a plurality of wrapper rolls 82, and a plurality of air cylinders 83. In the hot-rolled coiler 8, the steel strip 9 derived from the pinch roll 80 is coiled by the mandrel 81. Further, the plurality of wrapper rolls 82 arranged around the mandrel 81 perform an opening / closing operation so as to adjust the distance from the mandrel 81 by the air cylinder 83 provided in each wrapper roll 82. Then, the plurality of wrapper rolls 82 guide the tip of the steel strip 9 around the mandrel 81 and press the steel strip 9 against the mandrel 81 to generate a frictional force between the steel strip 9 and the mandrel 81. The steel strip 9 is tightly wrapped around the mandrel 81.

The fluid switching valve 1 is provided by being connected to a plurality of air cylinders 83, respectively, and controls the operation of each air cylinder 83. The operation of the air cylinder 83 includes an opening operation in which the air cylinder 83 contracts, a closing operation in which the air cylinder 83 expands, and a neutral operation in which the expansion and contraction operation of the air cylinder 83 stops. Further, in the opening operation of the air cylinder 83, the wrapper roll 82 moves away from the mandrel 81, and in the closing operation of the air cylinder 83, the wrapper roll 82 moves closer to the mandrel 81.
As shown in FIG. 1, the fluid switching valve 1 includes a frame 2, a spool 3, a pair of inner pistons 4 and 5, and a rod 6.
The frame 2 has an outer frame 20, an inner frame 21, and sealing members 22 and 23.

The outer frame 20 is a substantially cylindrical metal member extending in the left-right direction of FIG. 1, and a substantially cylindrical cavity is formed inside. Holes into which the rod 6 is inserted are formed at both ends of the outer frame 20 in the extending direction. Further, supply ports 200 and 201, which are supply / discharge paths for operating air and communicate with the inner cavity, are formed on the side surfaces (lower surface in FIG. 1) on both ends of the outer frame 20 in the extending direction. The supply ports 200 and 201 are connected to operation air supply / discharge devices (not shown), respectively, and operation air, which is low-pressure air of about ^{4 kg / cm 2 is supplied or discharged according to the operation to the air cylinder 83.} .. Further, on the side surface of the outer frame 20 (lower surface in FIG. 1), an input port 202, which is a supply path for working air, and a first output port 203 and a second output port 204, which are discharge paths for working air, are formed. To. The input port 202, the first output port 203, and the second output port 204 are holes communicating with the inner cavity of the outer frame 20. Further, the input port 202 is connected to a working air supply device (not shown), and working air which is high pressure air of about ^{20 kg / cm 2 is supplied from the working air supply device.} Further, the first output port 203 and the second output port 204 are connected to the air cylinder 83, and the working air supplied from the input port 202 is output to the air cylinder 83 according to the position of the spool 3. Further, on the inner surface of the outer frame 20, a pair of projecting portions 205, 206 that project inward in the radial direction and fix the inner frame 21 are formed so as to be separated from each other by the length of the inner frame 21 in the extending direction.

The inner frame 21 is a substantially cylindrical metal member. The inner frame 21 is fixed to the inner surface of the center of the outer frame 20 in the extending direction in a state where both ends in the extending direction (horizontal direction in FIG. 1) are in contact with the pair of protruding portions 205 and 206 of the outer frame 20. .. _{The inner frame 21 has three regions, a first region D 1} to a third region D ₃ , which are arranged in the extending direction. The first region D ₁ to the third region D ₃ are located at positions corresponding to the input port 202, the first output port 203, and the second output port 204, respectively. The central portion of the first region D ₁ to the third region D _{3 in} the extending direction has a smaller outer diameter and a larger inner diameter than the end portion including the boundary of _{each region D 1 to} D _3. Further, a plurality of holes 210 to 212 arranged in the circumferential direction are formed in the central portion of the first region D ₁ to the third region D _{3 in the extending direction.} Further, the outer peripheral surface of each end of the first region D ₁ to the third region D _{3 in} the extending direction abuts on the inner surface of the outer frame 20.

The sealing member 22 is a sealing member such as an O-ring made of a material such as synthetic rubber or high-performance resin. The seal member 22 is embedded in the inner surface of the end portion (in the example shown in FIG. 1, four locations arranged in the left-right direction) including the boundary between _{the first region D 1} to the third region D _{3 of the inner frame 21.} A groove is formed on the inner surface of the end portion of the inner frame 21 _{including the boundary between the first region D 1} to the third region D _{3 so that the seal member 22 can be embedded.} The seal member 22 prevents the inflow of fluid and foreign matter in each region of _{the first region D 1} to the third region D ₃ and the outflow of working air from each region when the spool 3 is inserted.

Like the seal member 22, the seal member 23 is a sealing member such as an O-ring made of a material such as synthetic rubber or high-performance resin. The seal member 23 is embedded in each of the inner surfaces of the holes into which the rods 6 provided at both ends of the outer frame 20 in the extending direction are inserted. A groove is formed on the inner surface of the holes at both ends of the outer frame 20 in the extending direction so that the seal member 23 can be embedded. The seal member 23 prevents the inflow of fluid and foreign matter into the frame 2 and the outflow of operating air from the frame 2 through the holes at both ends of the outer frame 20 in the extending direction in the state where the rod 6 is inserted.

The spool 3 is a columnar metal member, and is provided inside the inner frame 21. In the spool 3, a small diameter portion 30 having a constricted shape having a diameter smaller than that of other portions is formed in the center of the extending direction (horizontal direction in FIG. 1). The length of the small diameter portion 30 (the length of the spool 3 in the extending direction) is set shorter than the adjacent distance between the seal members 22. Further, the spool 3 is formed with a hole extending in the extending direction of the spool 3 and through which the rod 6 is inserted. The spool 3 is provided with the side surfaces excluding the small diameter portion 30 held by the seal member 22, and is configured to be movable only in the uniaxial direction which is the extending direction. As will be described later, the spool 3 switches the flow direction of the working gas by controlling the supply path of the working gas according to the stop position.

The pair of inner pistons 4 and 5 are bottomed cylindrical metal members having bottoms and open portions on both ends in the height direction (horizontal direction in FIG. 1), and both ends in the extending direction from the inner frame 21. It is provided so as to be slidably fitted inside the outer frame 20 on the side. The bottoms of the pair of inner pistons 4 and 5 are arranged on the opposite side of the inner frame 21 in the extending direction of the outer frame 20, that is, on the end side of the outer frame 20 in the extending direction, and the open portion is on the inner frame 21 side. It is distributed to each. Further, the pair of inner pistons 4 and 5 are configured so that the spool 3 can be inserted from the open portion side. Further, the bottom of the pair of inner pistons 4 and 5 is provided with a hole through which the rod 6 can be inserted and having a diameter smaller than the outer diameter of the end of the spool 3.

The rod 6 is a columnar metal member. The rod 6 is fixed to the spool 3 in a state of being inserted into the hole of the spool 3, so that the rod 6 has an integral structure with the spool 3. Further, both ends of the rod 6 in the extending direction (left-right direction in FIG. 1) are inserted into the holes at both ends of the outer frame 20 in the extending direction and are provided so as to project from the outer frame 20. As will be described later, the length of the rod 6 is such that both ends of the rod 6 can protrude outward from the outer frame 20 regardless of the position inside the frame 2 where the spool 3 is located.

<Operation of fluid switching valve>
Next, the operation of the fluid switching valve 1 according to the present embodiment will be described with reference to FIG. The fluid switching valve 1 controls the operation of the air cylinder 83 by changing the flow direction, which is the flow path of the high-pressure working air supplied to the air cylinder 83. As described above, there are three types of operations of the air cylinder 83: an open operation, a closed operation, and a neutral operation. The fluid switching valve 1 controls the operation of the air cylinder 83 by changing the flow direction of the operating air from the first output port 203 and the second output port 204 due to the difference in the supply / discharge directions of the operating air.

FIG. 3A shows a neutral state, which is a state of the fluid switching valve 1 when the air cylinder 83 is operated in a neutral state. When the air cylinder 83 is operated in a neutral state, the working air is not output from the first output port 203 and the second output port 204 of the fluid switching valve 1, and the air cylinder 83 is in a neutral state, and the expansion and contraction operation of the air cylinder 83 by the working air is stopped. ..
When performing the neutral operation, operating air is supplied to the supply ports 200 and 201. Then, the inner pistons 4 and 5 are pushed toward the inner frame 21 by the pressure of the operating air, and the spool 3 is stopped at the center position of the inner frame 21 to be in a neutral state. In the neutral state, the flow path of the working air is cut off between _{the first region D 1} and the second region D ₂ and between the first region D ₁ and the third region D _{3, and is supplied from the input port 202.} The working air to be generated is not output from either the first output port 203 or the second output port 204.

Here, the end portion of the first output port 203 side is the first length L ₁ the length protruding from the outer frame 20 of the rod 6, the ends of the second output port 204 side of the rod 6 from the outer frame 20 The protruding length is defined as the second length L ₂ . In the present embodiment, the rod 6 is provided so that _{the first length L 1} and the second length L ₂ have the same length in the neutral state in which the spool 3 is stopped at the center position.

FIG. 3B shows a first state, which is a state of the fluid switching valve 1 of the fluid when the air cylinder 83 is opened. When the air cylinder 83 is opened, the working air is output from the first output port 203 of the fluid switching valve 1, and the working air is not output from the second output port 204. Then, the working air output from the first output port 203 acts to cause the air cylinder 83 to contract.

When the opening operation is performed, the operation air is discharged from the supply port 200, and the operation air is supplied to the supply port 201. Then, the pressure inside the outer frame 20 on the second output port 204 side rises due to the pressure of the operating air, so that the spool 3 is pushed toward the first output port 203 side, and the first output port of the inner frame 21 is pushed. It is in the first state stopped at the first position on the 203 side. In the first state, _{a flow path of working air is secured between the first region D 1} and the second region D _2, and a flow path of working air is secured between the first region D ₁ and the third region D _3. It is blocked. Thus, working air supplied from the input port 202, through the first region _{D 1} and the second region _{D 2,} is output from the first output port 203. Further, in the first state, since the spool 3 stops at the first position, the first length L ₁ is longer than the second length L _2.

FIG. 3C shows a second state, which is a state of the fluid switching valve 1 of the fluid when the air cylinder 83 is closed. When the air cylinder 83 is opened, the working air is output from the second output port 204 of the fluid switching valve 1, and the working air is not output from the first output port 203. Then, the working air output from the second output port 204 acts to extend the air cylinder 83.

When the closing operation is performed, the operating air is discharged from the supply port 201, and the operating air is supplied to the supply port 200. Then, the pressure inside the outer frame 20 on the first output port 203 side rises due to the pressure of the operating air, so that the spool 3 is pushed toward the second output port 204 side, and the second output port of the inner frame 21 is pushed. It becomes the second state stopped at the second position on the 204 side. In the second state, _{a flow path of working air is secured between the first region D 1} and the third region D _3, and a flow path of working air is secured between the first region D ₁ and the second region D _2. It is blocked. Thus, working air supplied from the input port 202, through the first region _{D 1} and the third region _{D 3,} is outputted from the second output port 204. Further, in the second state, since the spool 3 stops at the second position, the second length L ₂ is longer than the first length L _1.

Here, the conventional fluid switching valve 1a is shown in FIG. As shown in FIG. 4, the conventional fluid switching valve 1a is the same as the fluid switching valve 1 according to the present embodiment with respect to the rod 6 and other configurations although there is no configuration related thereto. Specifically, unlike the fluid switching valve 1, the spool 3 of the fluid switching valve 1a is not formed with a hole through which the rod 6 is inserted. Further, holes through which the rod 6 is inserted are not formed at both ends of the outer frame 20 in the extending direction.

The operation of the conventional fluid switching valve 1a having such a configuration is shown in FIG. In FIG. 5, (A) is the case where the fluid switching valve 1a is in the neutral state, (B) is the case where the fluid switching valve 1a is in the first state, and (C) is the case where the fluid switching valve 1a is in the second state. Each case is shown. The switching operation of the fluid switching valve 1a is the same as the operation described with reference to FIG. That is, in the fluid switching valve 1a, the flow direction of the working air at the first output port 203 and the second output port 204 is controlled by controlling the supply and discharge of the operating air. As shown in FIG. 5, in the conventional fluid switching valve 1a, the stop position (neutral state) of the spool 3 is determined according to the state (neutral state, first state or second state) of the fluid switching valve 1a as in the present embodiment. Position, first position or second position) changes. However, in the fluid switching valve 1a, since the spool 3 is covered with the frame 2, the stop position of the spool 3 could not be confirmed.

In contrast, in the fluid switching valve 1 according to the present embodiment, as described above, in accordance with the stop position of the spool 3, a first length L ₁ of the rod 6 and the second length L ₂ is varied .. Therefore, by checking the first length L ₁ and the second length L ₂ , the position of the spool 3 inside the frame 2 can be confirmed, so that the state of the fluid switching valve 1 is in the neutral state. , It is possible to confirm whether it is the first state or the second state. That is, according to the fluid switching valve 1 according to the present embodiment, it is possible to easily confirm the malfunction of the fluid switching valve by confirming _{the first length L 1} and the second length L _2.

For example, a case where a malfunction occurs in the fluid switching valve 1 and a malfunction occurs in which the spool 3 does not move when the fluid switching valve 1 is switched from the neutral state to the first state will be described. In this case, when the operation air is supplied to the supply port 201 from the neutral state of FIG. 3A and the operation air is discharged from the supply port 200, the spool 3 is stuck due to reasons such as sticking of the spool 3. Suppose that a state occurs in which does not move to the neutral position. If such malfunction occurs, the supply path of the working gas from the first region D ₁ to the second region D ₂ is remains blocked, can not be output working air from the first output port 203 , The operation of Atsunobu Koira 8 is stopped.

In such a case, in the fluid switching valve 1 according to the present embodiment, the first length L ₁ and the second length L ₂ have the same length, or the first length L ₁ is larger than the normal first state. It is short and the second length L ₂ is long. Therefore, it is possible to easily confirm the malfunction of the fluid switching valve 1. Further, in such a state of malfunction, if the cause is sticking of the spool 3, the malfunction can be temporarily eliminated by forcibly moving the spool 3. In the fluid switching valve 1 according to the present embodiment, since a part of the rod 6 having an integral structure with the spool 3 protrudes to the outside of the frame 2, the rod 6 can be moved manually or mechanically. it can. For example, in the case of the above-mentioned malfunction example, the malfunction can be eliminated by moving the rod 6 in the extending direction (for example, moving it to the left side in FIG. 3A).

Further, when the rod 6 integrated with the spool 3 is extended to the outside of the frame 2, it is considered that a reel of operation air is generated from the seal portion of the frame 2, that is, the seal member 23 of the outer frame 20, and a malfunction occurs. It was. However, as a result of confirming the amount of air leak in the seal member 23 of the fluid switching valve 1 according to the present embodiment, the present inventors have confirmed that the fluid switching valve 1 has almost no effect on the operation. Further, it has been confirmed that in an environment such as a steel mill where the supply amount of low-pressure air is sufficiently prepared as in the present embodiment, no operational problem occurs if the amount of air leak is such that the operation is not affected. ..

<Modification example>
Although the present invention has been described above with reference to specific embodiments, it is not intended to limit the invention by these descriptions. By reference to the description of the invention, one of ordinary skill in the art will appreciate other embodiments of the invention that include various modifications as well as the disclosed embodiments. Therefore, it should be understood that the embodiments of the invention described in the claims also include embodiments including these modifications described herein alone or in combination.

For example, in the above embodiment, the fluid switching valve 1 is a three-way switching valve, but the present invention is not limited to this example. For example, the fluid switching valve 1 may be a two-way switching valve or a four-way switching valve.
Further, in the above embodiment, the fluid switching valve 1 is an air-driven type driven by operating air, but the present invention is not limited to such an example. For example, the fluid switching valve 1 may be of a hydraulically driven type driven by flood control. Further, oil may be used instead of the working air.

Further, in the above embodiment, the rod 6 is configured to protrude from both end sides of the frame 2, but the present invention is not limited to such an example. For example, the rod 6 may be configured to protrude from only one of the extending directions of the frame 2. Even in this case, the position of the spool 3 can be confirmed by confirming the length of the rod 6 protruding from the frame 2.

Further, in the above embodiment, the fluid switching valve 1 is used for the hot-rolled coiler 8, but the present invention is not limited to such an example. The fluid switching valve 1 may be used in other devices or equipment as long as it switches the flow direction of a fluid such as air or oil.
Further, in the above embodiment, the rod 6 is fixed to the spool 3 to form an integral structure, but the present invention is not limited to such an example. The rod 6 may be integrally configured with the spool 3 so that it can move according to the movement of the spool 3, and may be integrally molded with the spool 3, for example.

<Effect of embodiment>
(1) The fluid switching valve 1 according to one aspect of the present invention is a fluid switching valve 1 that switches the flow direction of a fluid (for example, working air), and is a frame 2 having a cavity inside and a frame 2. A spool 3 that is uniaxially movable in the cavity and switches the fluid flow direction according to the stop position, is fixed to the spool 3, and projects to the outside of the frame 2 at least on one end side in the uniaxial direction of the frame 2. The rod 6 is provided.

According to the configuration of (1) above, the stop position of the spool 3 inside the frame 2 can be easily confirmed by confirming the length of the rod 6 protruding to the outside of the frame 2. Therefore, when a malfunction occurs in the equipment using the fluid switching valve 1, it becomes possible to easily determine whether or not the malfunction of the fluid switching valve 1 is the cause. Further, since the malfunction of the fluid switching valve 1 can be easily determined, in the equipment using the fluid switching valve 1, the cause of the malfunction of the equipment is the malfunction of the fluid switching valve 1 or another device. It will be possible to easily determine whether it is due to a defect in the. Therefore, in the equipment using the fluid switching valve 1, the time required for the restoration of the equipment can be shortened. Further, when the malfunction of the fluid switching valve 1 can be recovered by forcibly moving the spool 3, the spool 3 can be moved by moving the rod 6, so that the malfunction can be temporarily recovered. Can be done in a short time.

(2) In the configuration of (1) above, the spool 3 is moved by air drive and is used for controlling the air cylinder 83 of the wrapper roll 82 in the hot-rolled coiler 8 for winding the steel strip 9.
According to the configuration of (2) above, when a malfunction occurs in the hot-rolled coiler 8, it is possible to shorten the time required for identifying the cause of the malfunction and recovering it.

As an example, the present inventors operate using the fluid switching valve 1 according to the above embodiment, and recover the operation when the fluid switching valve 1 is used and when the conventional fluid switching valve 1a is used. We verified the difference in time.
As a result of the embodiment, when the conventional fluid switching valve 1a is used, the hot-rolled coiler 8 malfunctions 9 times a year, and 3 for each restoration to replace the fluid switching valve 1a. It took about an hour. In the subsequent inspection of the fluid switching valve 1a, it was confirmed that all of these malfunctions were malfunctions due to the sticking of the fluid switching valve 1a. On the other hand, when the fluid switching valve 1 according to the above embodiment is used, at least one _{of the first length L 1} and the second length L _{2 of the rod 6 should be confirmed as the cause of these malfunctions.} Can be specified by. Furthermore, the inventors have confirmed that by manually moving the rod 6, the time required for restoration can be shortened to about 5 minutes each time.

1 Fluid switching valve 2 Frame 20 Outer frame 200, 201 Supply port 202 Input port 203 1st output port 204 2nd output port 21 Inner frame 210-212 Holes 22, 23 Sealing member 3 Spool 30 Small diameter part 4, 5 Inner piston 6 Rod 8 Hot-rolled coiler 80 Pinch roll 81 Mandrel 82 Wrapper roll 83 Air cylinder D ₁ 1st area D ₂ 2nd area D ₃ 3rd area L ₁ 1st length L ₂ 2nd length

Claims (2)

A fluid switching valve that switches the flow direction of fluid.
A frame with a cavity inside and
A spool that is provided in the cavity of the frame so as to be movable in the uniaxial direction and that switches the flow direction of the fluid according to the stop position.
A rod that is integrally formed with the spool and is provided so as to project to the outside of the frame at least on one end side in the uniaxial direction of the frame.
A fluid switching valve characterized by being provided with. The spool moves by air drive
The fluid switching valve according to claim 1, wherein the fluid switching valve is used for controlling an air cylinder of a wrapper roll in a hot-rolled coiler for winding a steel strip.

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