JPS605367B2 - Piston displacement detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston displacement detection device, and in particular to a piston displacement detection device for use in locations where accurate displacement detection is required, such as the piston or piston rod of a roll reduction cylinder of a multi-stage rolling mill. A displacement detection device is provided.

First, a conventional piston displacement detection device will be described with reference to FIGS. 1 and 2.

FIG. 1 is a diagram showing a roll position control system of a multi-high rolling mill equipped with a rotary piston displacement detection device.

In FIG. 1, the multi-high rolling mill includes a pair of work rolls 14, 14 supported within a mill housing 12, and a plurality of reinforcing rolls 16 arranged in multiple stages to back up the work rolls.

A packing bearing 18 is arranged behind and in contact with the reinforcing roll 16. A total of four packing bearings are provided, one pair each on the operation side (the front side in Figure 1) and the drive side (the opposite side in Figure 1) of the reinforcing roll, and the one on the operation side and the one on the drive side are synchronized, respectively. The shafts 20 and 2 are connected together so as to rotate together. On the operating side and on the drive side, a pair of packing bearings 18,
A tooth pattern is formed on the inside of the sector gear 18, and meshes with tooth patterns formed on both sides of the sector gear 22 extending vertically therebetween.

Hydraulically actuated cylinders are fixed to the mill housing via appropriate supports (not shown) on each of the operating side and the drive side. A piston device 24 is provided, and the sector gear 22 is connected to the lower end of a piston rod 28 that projects downward from a piston 26. An eccentric cam surface is formed on the circumferential surface of each packing bearing 18, and an eccentric cam surface is formed on the circumferential surface of each packing bearing 18.
2 is moved upward as shown by the arrow, each packing bearing 18 is rotated in the direction of the arrow, and the reinforcing roll 16 and work roll 14 are pushed down in the direction of the arrow by the D cam surface.

This roll lowering operation, that is, the roll closing operation, is performed by a flow control valve 30, in which hydraulic pressure from a pipe 32 connected to a hydraulic power source is passed through a pipe 34 to the cylinders on both sides. This is done by supplying the oil to the underside of the piston 26 of the piston device, and by connecting the oil chambers above the pistons of both piston-cylinder devices to the tank through pipes 36 and 38. Opening/closing valves 40 are provided in the pipes 34 and 36 as appropriate. The flow rate control valve 30 is operated by a command signal x from a flow rate setting device and a piston displacement detection signal Y fed back from a rotary piston displacement detection device 42, and controls the position of the piston 26, that is, the lower layer of the rolling roll. do.

That is, when the value of the piston displacement detection signal Y and the value of the command signal X become equal, the input to the flow control valve 30 is stopped and the piston 26 is stopped, forming a so-called position servo system. In the illustrated example, only the cylinder/piston device 24 on the operating side constitutes the position servo system, but this is because both sides of the synchronized shaft 20 operate synchronously. Therefore, the conventional rotary piston displacement detection device 42 includes a detection rack 44 provided on the piston rod 28, and a detection pinion 46 that meshes with the rack.
, and a rotational position detector 48 connected to the shaft of the pinion and converting its rotational displacement into an electrical signal.

In addition, reference number 5 indicates a piston position indicator connected to the piston rod on the other side. Since the conventional rotary piston displacement detection device 42 had the above-described structure, the protruding rack 44 and the detection pinion 46
The disadvantage is that play and looseness in the meshing parts and rotation transmission parts make position detection inaccurate, resulting in large detection errors. Also, if a mechanism is provided for play and control, the piston 2
There was a problem that it became impossible to follow the long stroke motion and high speed motion of No. 6. Furthermore, the piston rod 28 undergoes deformation such as bending due to external loads, resulting in a large detection error.

FIG. 2 is a diagram showing the structure of a conventional direct-acting piston displacement detection device, and this diagram also partially shows the case where it is used for roll position control of a multi-high rolling mill similar to FIG. 1. There is.

Reference numbers in FIG. 2 that are the same as those in FIG. 1 indicate the same or corresponding parts, respectively.

In FIG. 2, a fluid pressure operated (hydraulic operated) cylinder/piston device 24 is fixed to the mill housing 12 via a support fitting 23.

The cylinder-piston device includes a cylinder 25 and a piston 26 that is iron-fitted to a cylindrical inner cavity of the cylinder to form two upper and lower oil chambers 25A and 25B. ) has a piston rod 28 integrally fixed thereto. The piston rod is supported against lateral vibration by a sealed bearing 52 provided at the bottom of the cylinder.
and protrudes outward.

A sector gear 22 is connected to the lower end of the piston rod 28, and teeth formed on both sides of the sector gear mesh with teeth formed inside the pair of packing bearings 18, 18. Therefore, as in the case of FIG.
and move the sector gear 22 in the direction of the arrow (upward).
When the packing bearings 18, 18 are displaced in the direction of the arrow in the figure, the packing bearings 18, 18 are rotated in the direction of the arrow in the figure. Since an eccentric cam surface is formed on the circumferential surface of the packing bearing, the reinforcing roll and the work roll (see FIG. 1) are rolled down as the packing bearing rotates. In the conventional piston displacement detection device, as shown in the figure, a guide rod 58 is fixed to the upper surface of the piston 26 and passes through an opening 56 in the cylinder end wall 54, and a displacement meter movable portion is attached to the tip of the guide rod. 60 , while a support 62 fixed to the end wall 54 of the cylinder 25
Attach the displacement meter fixing part 64 to the.

The displacement meter movable section 60 extends through the displacement meter fixed section, and can electrically detect the displacement of the displacement meter movable section based on the displacement of the piston. Such a direct-acting displacement meter is generally of a type called a differential transformer.
Since the conventional direct-acting piston displacement detection device had the above structure, as shown in the figure, the piston rod 28
There is a drawback that the piston 26 is tilted due to the bending, resulting in a large detection error.

Furthermore, the installation height of the piston/cylinder device is increased, and the displacement detection section is caused to lateral shake due to the impact force when the rolled material is caught, resulting in a large detection error.In addition, the detection error due to thermal expansion of the detection section is disadvantageous. It also had the disadvantage of being easy to cause. An object of the present invention is to provide a piston displacement detection device that eliminates the drawbacks of the conventional piston displacement detection device as explained above with reference to FIGS. 1 and 2, and improves detection accuracy, durability, and reliability. With the goal.

The present invention fixes a hollow rod on the opposite side of the piston from the piston rod to form a double rod shape, and also supports the hollow rod with a cylinder to create a three-point support structure that prevents bending and inclination of the hollow rod and the piston. In addition, the fixed part of the displacement meter is pivoted to the support, and the movable part is pivoted to the piston side via the holding rod.

The other end of the rod is supported by a hollow rod via an elastic body, so that even if the piston is tilted, the displacement meter remains aligned with the piston's axis in all directions, allowing accurate piston displacement. It is designed so that it can be detected. Hereinafter, embodiments of the present invention will be described with reference to FIG.

FIG. 3, like FIG. 2, illustrates the case of use in a hydraulic cylinder/piston device forming a position servo system for controlling the roll rolling position of a multi-stage rolling mill as shown in FIG. 1. , Reference numbers in FIG. 3 that are the same as those in FIGS. 1 and 2 indicate the same or corresponding parts, respectively.

In FIG. 3, a hydraulically actuated cylinder/piston device 24 equipped with a piston displacement detection device of the present invention is installed in a mill housing 12 of a rolling mill via a support fitting 23.

The cylinder-piston device has a cylinder 25 and a piston 26 which is slidably and sealingly fitted into the cylindrical bore of the cylinder, and on one side (lower side) of the piston is a piston rod connected to a load. 28 are integrally fixed.

The load in this case is as in the case of Figures 1 and 2,
This is a rolling roll of a multi-high rolling mill that is rolled down via a sector gear 22 and a packing bearing 18. The piston rod is supported by a sealed bearing 52 in the lower end wall of the cylinder 25.

However, in the piston displacement detection device of the present invention,
A hollow rod 66 is fixed to the upper side of the piston 26, that is, on the opposite side to the piston rod 28.

As shown, the hollow rod has an outer diameter large enough to form a sufficient space inside, and is supported by a sealed bearing 701 provided on the upper end wall 68 of the cylinder 25. That is, in the present invention, the piston 26 is a double rod type piston having rods 28 and 66 on the upper side and the lower side, and is supported to the cylinder 25 at three points: the piston tank moving surface and the upper and lower bearings 52 and 70. It is now possible to do so. A hollow holding rod 74 for holding the displacement meter movable part 72 is supported within the hollow rod 66 .

The retaining rod 74 is supported at its lower end by a pivot 76 which is oblique and rotatable with respect to the piston 26, and its upper end is supported by a hollow rod end face inner flange 78 and a retainer rod outer flange 80. It is held within the hollow rod 66 by being pressed downward by a compression coil spring 82 disposed between. Therefore, the retaining rod 74
is supported in such a way that bending effects do not act at all. On the other hand, a case-shaped support 84 is fixed to the upper end wall 68 of the cylinder 25 and projects upward to form a space surrounding the hollow rod 66.

The support has an upper end wall 84A, a guide rod 86 extending downward is attached to the upper end wall, and a displacement meter fixing part 88 is fixed to the tip of the guide rod. The guide rod 86 is tiltably and rotatably mounted to the support 84 by a pivot 90 formed at the upper end and a compression spring 96 disposed between the flange portion 92 of the guide rod and the engaging portion 94 of the upper end wall 84A. It is being

The guide rod 86 extends into the holding rod 74, and the displacement meter fixing part 88 at the tip of the guide rod extends through the displacement meter movable part 72 provided inside the holding rod, forming a so-called diamond shape. It constitutes a working transformer.

In the illustrated example, the guide rod 86 is prevented from lateral wobbling by two slide bearings 98, 98 provided within the holding rod, so that its straightness with respect to the holding rod 74 can be reliably maintained. Further, the lower end pivot support portion 76 of the holding rod 74 is provided at a position as close to the piston 26 as possible, and the position of the pivot is such that the upper bearing 70 and the lower bearing 5
It is between. This allows the lateral displacement of the retaining rod 74 to be minimized even if the piston 26 is tilted. The piston displacement detection device according to the embodiment of the present invention has the above configuration, and its operation is as follows.

By operating the flow control valve (flow control valve 30 in FIG. 1), hydraulic pressure is introduced into the lower oil chamber 25B and the upper oil chamber 25A is caused to pass through the tank, causing the piston 26 to rise.

As the piston moves up, the piston rod 28, the hollow rod 66, and the holding rod 74 supported within the hollow rod
, as well as a displacement meter movable part 72 provided within the holding rod.
rises. As shown in FIG. 3, when used in a multi-stage rolling mill, the segment gear 22 rises simultaneously with the rise of the piston rod 28, and the packing bearings 20, 20 engaged therewith rotate in the direction of the arrow. As the packing gear rotates, the reinforcing roll and work roll (see Figure 1) are rolled down to predetermined positions by the eccentric cam surface formed on the circumferential surface of the packing gear, thereby adjusting the rolling conditions of thin plates, alloy steel, etc. Control operations are performed. On the other hand, the displacement meter fixing part 88 is connected to the guide rod 8
Since the piston is installed on the side of the sill 25 via the support 84 that supports the piston 6, relative displacement occurs between it and the displacement meter movable part 72 as the piston rises.

This relative displacement is output as an electrical position signal by a displacement meter, and piston displacement is detected. In the embodiment shown in FIG. 3, the hollow rod 66 is integrally fixed to the piston 26, and Since the piston is supported by the bearing 70 of the sill ring 25, the piston is supported at three points, thereby preventing the piston from tilting.

Therefore, the straightness between the movable part 74 and the fixed part 88 of the displacement meter is ensured, and the detection error of piston displacement can be greatly reduced. Further, since the movable part and the fixed part of the displacement meter are supported by a pivot, it is possible to eliminate detection errors in piston displacement due to the influence of bending and bending. Furthermore, since the movable part and fixed part of the displacement meter are housed within the hollow rod 66, the measuring part can be protected from the external environment consisting of high-temperature steam containing scale and the like, and the structure can be made more compact.

In addition, from the piston to the displacement detection section (displacement meter movable section 72
Since the length (up to ) can be reduced, detection errors due to expansion and contraction of members due to temperature differences can be reduced. The embodiments of the present invention have been described above by illustrating the case where they are applied to a servo hydraulic cylinder device for rolling down rolling rolls that requires precise control of the position of rolling rolls, but the present invention is not limited to this. It can be widely applied to devices that detect and control the position of a pressure-actuated piston.

As is clear from the above description, the piston displacement detection device of the present invention greatly reduces the detection error by greatly reducing the deviation between the piston displacement and the movement (distance and direction) of the displacement measurement unit. This makes it possible to accurately detect and control the piston position.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a roll reduction counterfeit control system of a multi-roll rolling mill equipped with a conventional rotary piston displacement detection device, and Fig. 2 shows the main parts of a conventional direct-acting piston displacement detection device. FIG. 3 is a longitudinal sectional view showing the structure of an embodiment of the piston displacement detection device of the present invention. 24...Fluid operated cylinder/piston device,
25... Schilling, 26... Piston, 28... Piston rod, 30... Flow rate control valve, 52, 70.
... Bearing, 66 ... Hollow rod, 72 ...
... Displacement meter movable part, 74 ... Holding rod, 7
6...・Pivot, 84...Support, 86...
Guide rod, 88. ．． ...Displacement meter fixing part, 90.
·····pivot. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A piston displacement detection device for a fluid-pressure-operated cylinder-piston device having a piston rod on one side of the piston, wherein the piston extends beyond the cylinder in the axial direction of the piston on the opposite side from the piston rod and is fixed to the piston; and a hollow rod bearing the cylinder; a holding rod disposed within the hollow rod, one end of which is pivotally supported toward the piston, and the other end of which is supported by the hollow rod via an elastic body; A piston displacement detection device comprising: a support provided on the hollow rod side; a displacement meter movable portion disposed within the holding rod; and a displacement meter fixed portion pivotally supported by the support.