JP2001082417A - Method and device for detecting moving position of hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for detecting the moving position of a hydraulic cylinder wherein the moving position can be surely measured even if a hydraulic fluid or the like is leaked into the cylinder. SOLUTION: This device comprises a hydraulic cylinder 1, a rod-side pipe 2a and piston-side pipe 2b connected to the hydraulic cylinder 1, a rod-side flowmeter 3a for measuring the flow rate of the rod-side pipe 2a, a piston-side flowmeter 3b for measuring the flow rate of the piston-side pipe 2b, and an arithmetic device 5 for calculating the rod moving distance of the hydraulic cylinder 1 from the flow rate difference between both the flowmeters 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a lot moving distance of a hydraulic cylinder driven forward and backward by, for example, hydraulic pressure.

[0002]

2. Description of the Related Art Fluid pressure cylinders are used in many dedicated machine tools and automated machines, and are used for opening and closing devices and controlling the amount of opening and closing. In particular, the hydraulic cylinder used for opening / closing amount control is positioned at the designated position by controlling the hydraulic pressure or oil amount at the designated position while measuring the movement amount of the cylinder lot.

[0003] In the conventional movement amount measurement, for example, an electric measuring device is used, and a limit switch or a proximity switch is attached to a lot of a hydraulic cylinder or a moving object to detect a position. There is a position detection method attached to the pressure cylinder itself, and a mechanical method includes a potentiometer that utilizes the shortness of wire elongation.

Further, as a prior art of a position detecting means using a working fluid of a fluid pressure cylinder, Japanese Patent Application Laid-Open No. Sho.
Japanese Patent Application Publication No. 984 discloses a position indicating device for a hydraulic cylinder in which a flow indicator of a flow rate integrating type is connected to a hydraulic oil line of a hydraulic cylinder.
No. 3 discloses a hydraulic cylinder having a detecting means for detecting the fluid in conjunction with the inside of the cylinder into which the fluid is introduced when the sliding piston end surface of the hydraulic cylinder reaches a predetermined position. Is introduced.

[0005]

However, those using conventional electric measuring instruments and those using mechanical position detecting means can measure the moving amount of the fluid pressure cylinder with high resolution and high accuracy. In addition, it is necessary to install the moving amount measuring mechanism at the operating end near the fluid pressure cylinder, and if the measuring place is in an atmosphere of, for example, about 180 ° C., the equipment and the wiring become high temperature, so that it cannot be used.

On the other hand, the position detecting means using a working fluid can solve the above-mentioned problem of the measured atmosphere temperature, but the conventional technique introduced in Japanese Patent Application Laid-Open No. 48-29984 uses a hydraulic cylinder. If the working fluid leaks in the cylinder due to wear of the piston or cylinder inner wall in the case of continuing, there is a problem that the accuracy of measuring the moving amount is extremely reduced. Further, in the technique described in Japanese Patent Application Laid-Open No. 11-148503, Since the fluid outlet, which is the fluid detecting means, is provided at a predetermined position, continuous position detection is difficult.Moreover, since the hydraulic cylinder itself is machined, the moving distance detecting means is expensive and versatile. There was a problem of chipping. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a method and an apparatus for detecting a moving position of a fluid pressure cylinder which are strong in environment resistance, durable and inexpensive.

[0007]

In order to achieve the above object, the present invention is directed to a lot movement of a hydraulic cylinder in which a piston slides along an inner wall of a cylinder by a fluid introduced into the cylinder. At the time of position detection, a flow meter is connected to the working fluid path on the lot side and piston side of the cylinder, and the difference in both flow rates is divided by the difference in cylinder cross-sectional area between the lot side and piston side to measure the travel distance. It is. According to the present invention, the amount of movement can be measured based on the flow rate difference between the piston side and the lot side. Therefore, even if a leak of hydraulic oil occurs in the cylinder, the measurement accuracy is not reduced and the durability is strong. effective.

According to a second aspect of the present invention, there is provided a fluid pressure cylinder, a lot side pipe and a piston side pipe connected to the fluid pressure cylinder, a lot side flow meter for measuring a flow rate of the lot side pipe, and a piston. It comprises a piston-side flow meter for measuring the flow rate of the side pipe, and a calculating device for calculating the lot moving distance of the fluid pressure cylinder from the flow rate difference between the two flow meters.

According to the present invention, in addition to the effect of the first aspect, the operating end where the fluid pressure cylinder is installed is separated from the operating end without installing electric wiring or electric measuring equipment which is sensitive to temperature or the like. Since the electrical measuring device can be installed at the location, it is possible to configure the measuring device with strong environmental resistance, and it is also possible to measure the moving amount by installing the flow meter in the middle of the working fluid pipeline. Because it is possible, when detecting the movement position of the hydraulic cylinders with different operation timings, an arbitrary circuit may be configured with a switching valve, a check valve, etc. There is also the effect that the quantity can be measured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. FIG. 1 shows a configuration of the present invention, and FIG. 2 is a sectional view of a hydraulic cylinder for explaining the present invention. The invention according to claim 1 is as shown in FIG.
The flowmeter 3 is connected to the working fluid path on the lot side and the piston side of the fluid pressure cylinder 1, and the moving distance of the lot is calculated from the difference between the two flowmeters 3.

FIG. 2 shows the relationship between the moving distance of the lot and the flow meter difference.
This will be described below. FIG. 2 shows a state in which the working fluid is caused to flow on the piston side of the hydraulic cylinder 1 and the lot of the hydraulic cylinder 1 has moved the lot moving distance ΔL from the right side of the drawing. Symbols ΔV1, S1, and 11 in the drawings indicate the internal volume after movement on the piston side, the cross-sectional area on the piston side, and the discharge flow rate during the movement. Express. Symbol R indicates the leakage amount of the working fluid in the cylinder.

The internal volumes on the lot side and the piston side are represented by the following equations. ΔV1 = S1 · ΔL = Σ11 · t−R (1) ΔV2 = S2 · ΔL = Σ12 · t−R (2) Next, the internal volume difference between the lot side and the piston side is represented by the following equation (3). (ΔV2−ΔV1) = (S2−S1) · ΔL = Σ
(12−11) · t (3) Accordingly, the moving distance ΔL is ΔL = [Σ (12−11) · t] / (S2−S1) (4), and the moving distance of the lot and the flow meter difference are Measurement can be performed without being affected by the cylinder internal leak amount R. In this case,
As is clear from Equation 4, the flow meter 3 used in the present invention
May be a flow meter 3 of a flow integrating type, or a flow meter may be integrated, and the type of the flow meter 3 is not particularly specified.

Next, the second aspect of the present invention will be described. As shown in the schematic diagram of FIG. 1, the invention according to claim 2 is a hydraulic cylinder, a lot-side pipe 2a and a piston-side pipe 2b connected to the hydraulic cylinder 1, and a flow rate of the lot-side pipe 2a. A lot-side flow meter 3a for measuring
It comprises a piston-side flow meter 3b for measuring the flow rate of the piston-side pipe 2b and an arithmetic unit 5 for calculating the lot moving distance of the fluid pressure cylinder 1 from the flow rate difference between the two flow meters 3. The device 5 and the switching valve 4 and the arithmetic unit 5 are wired to exchange signals.

As described above, the flow meter 3 in this case does not specify the type. Since it is simpler to use the flowmeter 3 of the flowmeter type in terms of the equipment configuration, a method of calculating the moving distance will be described below using the flowmeter as an example. The arithmetic unit 5 basically uses the above four equations. The arithmetic unit 5 always measures the measurement values of the switching valve 4 and the flow meters 3, and detects the lot moving direction of the fluid pressure cylinder 1 based on the signal of the switching valve 4. The start of measurement of the flow meter 3 for measuring the moving distance is an error factor until the pressure of the fluid rises before the start of the lot transfer, so that the flow rate value of the discharge side of the working fluid starts to be measured. The moving distance is calculated by integrating the flow rate difference of No. 3 with time and dividing by the internal volume. Note that the signal of the switching valve 4 is used to reset the integrated value of the flow rate difference.

The arithmetic unit 5 of the present invention may be of the analog type, but the digital type is inexpensive in recent years. The measured movement distance is continuously output and used for the feedback control of the fluid pressure cylinder 1 or directly to the indicator 6.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is applied to a hydraulic cylinder 1 for driving the opening and closing of a sliding nozzle 17 of a ladle 15 in a continuous casting facility. As shown in FIG. 3, the continuous casting equipment continuously feeds molten steel 16 in a tundish 19 into a mold 20 to cast slabs.
, Molten steel 16 is injected through a sliding nozzle 17 and a long nozzle 18. When the molten steel 16 becomes empty, the ladle 15 is replaced with a ladle 15 filled with another molten steel 16, and the ladle 15 is left with the molten steel 16 in the dandysh remaining.
By continuously injecting the molten steel 16 in the inside, continuous casting is manufactured.

Each ladle 15 is provided with a sliding nozzle 17 for opening and closing the outlet of the molten steel 16 and a hydraulic cylinder 1 for driving the nozzle to open and close. At the time of replacement, the hydraulic oil line 2 is connected to the hydraulic cylinder 1 by the coupler 14 to control the opening and closing of the sliding nozzle 17. The opening / closing control of the sliding nozzle 17 is performed by taking the signal of the load cell 21 into the sliding nozzle controller 7 and controlling the tundish 1
Although the opening of the sliding nozzle is adjusted to keep the weight of the molten steel 16 in the casting 9 constant, continuous casting is performed when the ladle 15 is replaced, and the weight of the dandishes is smaller than the predetermined weight. After the replacement of the nozzle 15, the opening of the closed sliding nozzle is once fully opened, the molten steel 16 is injected to a predetermined tundish weight, and thereafter the opening is controlled so that the tundish weight becomes constant.

However, in this opening / closing control, if the weight of the dandishes exceeds a predetermined value, the sliding nozzle 17
Operates in the closing direction and the outlet of the molten steel 16 may be too narrowed. If the throttle is excessively narrowed, the flow rate in the long nozzle 18 decreases, and the molten steel 16 is cooled at the ambient atmospheric temperature, and the sliding nozzle 17 is blocked, so that continuous casting must be stopped. It is necessary to constantly monitor the opening in order to prevent the outlet from being excessively restricted, and the present invention is applied to the detection of the opening position.

FIG. 3 shows a hydraulic circuit diagram of the sliding nozzle opening control according to one embodiment of the present invention. In this embodiment, since the diameter of the sliding nozzle 17 is 60 mm, and the opening of the sliding nozzle and the moving amount of the hydraulic cylinder 1 are in a proportional relationship, the flow meter 3 is installed in the hydraulic oil pipe and the measured value is calculated by an arithmetic unit. 5 and the sliding nozzle opening was measured from the flow rate difference between the inflow side and the discharge side of the hydraulic oil described above. The measured opening is displayed on the indicator 6 and taken into the sliding nozzle controller 7 so that the opening of the sliding nozzle does not become 10 mm or less.
It was used as the opening limit value for opening control based on the weight of the touch.

As a result, the hydraulic cylinder 1 of the ladle 15
Some of them were aging and internal leaks occurred, but without causing nozzle blockage during continuous casting,
The nozzle opening accuracy is about ± 1 mm, which can provide sufficient accuracy for practical use. Even if the hydraulic cylinder 1 is installed at a very high temperature of 150 ° C. on the molten steel surface, a failure occurs for a long time. Stable operation without any problems.

[0021]

Since the method and apparatus for detecting the moving position of the fluid pressure cylinder according to the present invention are as described above, a moving position detecting mechanism which is strong in environment resistance, durable and inexpensive can be provided. There is an effect.

As described above, according to the first aspect of the present invention, since the movement amount can be measured based on the flow rate difference between the piston side and the lot side, even if the operating oil leaks in the cylinder, There is an effect that the durability is strong without lowering the measurement accuracy. The invention according to claim 2 further comprises installing an electric measuring device at a location away from the operating end without installing electric wiring or electric measuring device that is weak against temperature or the like at the operating end where the fluid pressure cylinder is installed. Therefore, there is an effect that a measuring instrument configuration having high environmental resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a device configuration of the present invention.

FIG. 2 is a sectional view of a fluid pressure cylinder for explaining the present invention.

FIG. 3 is a hydraulic circuit diagram of a sliding nozzle opening control according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluid pressure cylinder (hydraulic cylinder) 2 Working fluid pipeline (Hydraulic fluid pipeline) 2a Lot side piping 2b Piston side piping 3 Flow meter 3a Lot side flow meter 3b Piston side flow meter 4 Switching valve 5 Arithmetic unit 6 Indicator 7 Sliding Nozzle control device 8 Relief valve 9 Pressure gauge 10 Valve 11 Pump 12 Filter 13 Tank 14 Coupler 15 Ladle 16 Molten steel 17 Sliding nozzle 18 Long nozzle 19 Tundish 20 Mold 21 Load cell 22 Check valve

Claims (2)

[Claims] When detecting a lot moving position of a fluid pressure cylinder (1) in which a piston slides along an inner wall of the cylinder by a fluid introduced into the cylinder, a flow rate is set to a working fluid path on a lot side and a piston side of the cylinder. A method of detecting the movement position of a fluid pressure cylinder, in which a flow rate difference is measured by connecting a total flow rate difference between the two flow rates by dividing the difference between the flow rates of the lot and the piston. 2. The flow rate of a fluid pressure cylinder (1), a lot-side pipe (2a) and a piston-side pipe (2b) connected to the fluid pressure cylinder (1), and a flow rate of a lot-side pipe (2a) are measured. Lot side flow meter (3a) and piston side piping (2
b) a fluid pressure comprising a piston-side flow meter (3b) for measuring the flow rate and an arithmetic unit (5) for calculating the lot moving distance of the fluid pressure cylinder (1) from the flow rate difference between the two flow meters (3). Cylinder movement position detection device.