CN109944838B - Servo valve mechanical zero on-line zero setting method - Google Patents

Servo valve mechanical zero on-line zero setting method Download PDF

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CN109944838B
CN109944838B CN201910281824.3A CN201910281824A CN109944838B CN 109944838 B CN109944838 B CN 109944838B CN 201910281824 A CN201910281824 A CN 201910281824A CN 109944838 B CN109944838 B CN 109944838B
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servo valve
zero
hydraulic cylinder
adjusting bolt
moving speed
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CN109944838A (en
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张强
王润楠
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Angang Steel Co Ltd
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Angang Steel Co Ltd
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Abstract

The invention relates to the technical field of instrument and meter debugging methods, in particular to a mechanical zero online zero setting method for a servo valve. Starting the pressure oil source normally; control signals are input when the servo valve is closed,Observing the moving direction of a hydraulic cylinder rod fed back by a displacement sensor under the no-load state of the hydraulic cylinder and recording the moving speed; adjusting a mechanical zero adjusting bolt of the servo valve, reducing the moving speed of the hydraulic cylinder in the direction until the speed is close to zero, and recording the position a and the speed Va of the adjusting bolt; when the hydraulic cylinder moves to the stroke end in a one-way mode, a control signal is manually operated or given to the servo valve, and the hydraulic cylinder is operated to move to the stroke middle position; continuously adjusting the mechanical zero adjusting bolt of the servo valve until the hydraulic cylinder slightly moves reversely, and when the moving speed V of the hydraulic cylinder isb=VaThen, recording the position b of the adjusting bolt; and adjusting the mechanical zero adjusting bolt of the servo valve again to the middle position of the position a and the position b. The method has the advantages of quick judgment, simple operation, easy realization and capability of meeting the precision requirement.

Description

Servo valve mechanical zero on-line zero setting method
Technical Field
The invention relates to the technical field of instrument and meter debugging methods, in particular to a two-stage servo valve mechanical zero online zero setting method without electric position feedback.
Background
The servo valve is generally applied to an important position of a pressure control system, and is a key influence link of stable operation of equipment and quality control of finished products. A hydraulic servo control system for edge alignment, deviation correction and centering of a continuous annealing unit of a cold rolling mill usually adopts a double-nozzle baffle type servo valve without electric position feedback and an external amplifier, and the frequent deviation correction vibration of a single deviation correction control loop during the operation of the unit causes the frequent mechanical zero deviation of the corresponding servo valve.
The one-way deviation of the strip steel is easily caused during the start-up and stop of the unit, and the deviation rectifying capability is influenced under the condition of automatically giving a bias electrical signal. The zero setting of a common servo valve needs to be carried out on a laboratory bench, and professional equipment and instruments are needed; meanwhile, the servo valve which cannot work normally must be replaced and offline, so that the whole system needs longer troubleshooting and shutdown maintenance, and the smooth production is seriously influenced.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides the servo valve mechanical zero online zero setting method which can be quickly judged, is simple to operate, is easy to realize and has acceptable precision.
In order to achieve the purpose, the invention is realized by adopting the following technical scheme.
A method for online zero adjustment of mechanical zero position of a servo valve specifically comprises the following steps:
1. starting a test loop, supplying oil and ensuring normal operation;
2. closing a servo valve to input a control signal, observing the moving direction of a cylinder rod of the hydraulic cylinder fed back by a displacement sensor under the no-load state of the hydraulic cylinder, and defining the moving direction as A;
3. fine-tuning a mechanical zero adjusting bolt of the servo valve, and reducing the moving speed of the cylinder rod in the direction A until the feedback speed is close to zero; recording the direction Ra, the position La and the moving speed Va of the cylinder rod of the rotating zero adjusting bolt;
4. when the hydraulic cylinder runs to the stroke end point, a control signal is manually operated or given to the servo valve, and the hydraulic cylinder is operated to move to the stroke middle position;
5. continuously adjusting the mechanical zero adjusting bolt of the servo valve along the direction until the cylinder rod moves reversely, and defining the moving direction as B;
6. when the moving speed Vb of the cylinder rod is reduced to Vb-Va which is less than or equal to 0.5Va, recording the direction Rb, the position La and the moving speed Vb of the cylinder rod of the rotating zero adjusting bolt;
7. adjusting the mechanical zero adjusting bolt of the servo valve again to the middle position of the position La and the position Lb;
8. manually operating or giving a control signal to a servo valve, operating a hydraulic cylinder to move for a certain distance, defining the hydraulic cylinder as a direction C, closing the servo valve control signal, and recording the moving speed Vc of a cylinder rod;
9. manually operating or giving a control signal to a servo valve, operating the hydraulic cylinder to move in a reverse direction for a certain distance, defining the direction D, closing the servo valve control signal, and recording the moving speed Vd of the cylinder rod;
10. zero setting end determination conditions:
in the technical parameters of the servo valve, hysteresis is recorded as Hy%, and resolution is recorded as Th%;
under the condition that a servo valve inputs a rated signal, the no-load rated moving speed of the hydraulic cylinder of the test loop is recorded as Ve;
after zero setting, recording the actually measured zero offset percentage of the servo valve as Bi%, and defining that Bi% is | Vc-Vd |/2 Ve;
the precision required by zero offset setting is recorded as Be%;
1) when the speed Vc is equal to Vd is equal to 0, the mechanical zero-position online zero-setting process of the servo valve is finished, and the servo valve can be determined to have no zero offset;
2) when the directions of the speeds Vc and Vd are opposite and one of the speeds is zero, if Bi is more than or equal to 0 and less than or equal to Th percent, the mechanical zero-position online zero setting process of the servo valve is finished, and the servo valve is determined to have no zero offset;
3) when the directions of the speeds Vc and Vd are opposite and one of the speeds is zero, if Th percent is more than or equal to Bi percent and less than or equal to Be percent, the mechanical zero position on-line zero setting process of the servo valve is finished, and the servo valve has zero deviation but is in an acceptable precision range;
4) and when the directions of the speeds Vc and Vd are opposite, but Bi% is larger than Be% or the directions of the speeds are the same, referring to the direction of the maximum moving speed of the cylinder rod and repeating the step 3 or the step 6, finely adjusting the mechanical zero position adjusting bolt of the servo valve, and repeating the steps 8-10.
Compared with the prior art, the invention has the beneficial effects that:
whether the servo valve has zero offset can be judged quickly on line, and the mechanical zero position on-line zero setting of the servo valve under a certain precision condition can be realized through simple operation.
Drawings
FIG. 1 is a schematic diagram of the present invention.
In the figure, ① -pressure oil source ② -oil tank ③ -servo valve ④ -hydraulic cylinder ⑤ -displacement sensor
Detailed Description
A method for online zero adjustment of mechanical zero position of a servo valve specifically comprises the following steps:
1. starting a test loop, supplying oil and ensuring normal operation;
2. closing a servo valve to input a control signal, observing the moving direction of a cylinder rod of the hydraulic cylinder fed back by a displacement sensor under the no-load state of the hydraulic cylinder, and defining the moving direction as A;
3. fine-tuning a mechanical zero adjusting bolt of the servo valve, and reducing the moving speed of the cylinder rod in the direction A until the feedback speed is close to zero; recording the direction Ra, the position La and the moving speed Va of a cylinder rod of the rotating zero adjusting bolt (taking a double-rod hydraulic cylinder as an example, other types need to calculate the flow rate according to the structural size of the hydraulic cylinder and uniformly use the flow rate for judgment, the same applies below);
4. when the hydraulic cylinder runs to the stroke end point, a control signal is manually operated or given to the servo valve, and the hydraulic cylinder is operated to move to the stroke middle position;
5. continuously adjusting the mechanical zero adjusting bolt of the servo valve along the direction until the cylinder rod moves reversely, and defining the moving direction as B;
6. when the moving speed Vb of the cylinder rod is reduced to Vb-Va which is less than or equal to 0.5Va, recording the direction Rb, the position La and the moving speed Vb of the cylinder rod of the rotating zero adjusting bolt;
7. adjusting the mechanical zero adjusting bolt of the servo valve again to the middle position of the position La and the position Lb;
8. manually operating or giving a control signal to a servo valve, operating a hydraulic cylinder to move for a certain distance, defining the hydraulic cylinder as a direction C, closing the servo valve control signal, and recording the moving speed Vc of a cylinder rod;
9. manually operating or giving a control signal to a servo valve, operating the hydraulic cylinder to move in a reverse direction for a certain distance, defining the direction D, closing the servo valve control signal, and recording the moving speed Vd of the cylinder rod;
10. zero setting end determination conditions:
in the technical parameters of the servo valve, hysteresis is recorded as Hy%, and resolution is recorded as Th%;
under the condition that a servo valve inputs a rated signal, the no-load rated moving speed of the hydraulic cylinder of the test loop is recorded as Ve;
after zero setting, recording the actually measured zero offset percentage of the servo valve as Bi%, and defining that Bi% is | Vc-Vd |/2 Ve;
the precision required by zero offset setting is recorded as Be%;
1) when the speed Vc is equal to Vd is equal to 0, the mechanical zero-position online zero-setting process of the servo valve is finished, and the servo valve can be determined to have no zero offset;
2) when the directions of the speeds Vc and Vd are opposite and one of the speeds is zero, if Bi is more than or equal to 0 and less than or equal to Th percent, the mechanical zero-position online zero setting process of the servo valve is finished, and the servo valve is determined to have no zero offset;
3) when the directions of the speeds Vc and Vd are opposite and one of the speeds is zero, if Th percent is more than or equal to Bi percent and less than or equal to Be percent, the mechanical zero position on-line zero setting process of the servo valve is finished, and the servo valve has zero deviation but is in an acceptable precision range;
4) and when the directions of the speeds Vc and Vd are opposite, but Bi% is larger than Be% or the directions of the speeds are the same, referring to the direction of the maximum moving speed of the cylinder rod and repeating the step 3 or the step 6, finely adjusting the mechanical zero position adjusting bolt of the servo valve, and repeating the steps 8-10.
Example (b):
as shown in fig. 1, the test circuit employs the following hydraulic elements:
a servo valve: MOOG G761-3001, rated flow 4L/min, hysteresis Hy% 3%, resolution Th% 0.5%
Hydraulic cylinder: the double out-of-bar hydraulic cylinders 80/56-158,
a displacement sensor: MTS RHM0250MD701S1G110 with resolution of 10 μm
The specific process of the mechanical zero position on-line zero setting is as follows:
1. starting a pressure oil source ①, ensuring that the oil supply pressure P reaches a system design value, and ensuring that a pipeline for returning oil to an oil return tank ② is smooth;
2. when the plug of the servo valve ③ is unplugged, the moving direction (left movement in the test example) of the cylinder rod of the hydraulic cylinder ④ fed back by the displacement sensor ⑤ is observed under the no-load state of the hydraulic cylinder ④ and is recorded as the direction A;
a method for measuring the moving speed of a cylinder rod includes the steps of observing the time T measured by a stopwatch when the displacement variation of the cylinder rod fed back by a displacement sensor ⑤ is 30mm, and obtaining the moving speed of the cylinder rod as V being 30/T.
3. The method comprises the following steps of finely adjusting a servo valve ③, namely, a mechanical zero position adjusting bolt (a test example is anticlockwise rotated), reducing the moving speed (leftward movement) of a hydraulic cylinder ④ in a direction A, recording the direction Ra (anticlockwise) of the rotating zero position adjusting bolt, the position La (an English allen wrench is used in the test example, the lower part is the same as the upper part, the long end of the wrench swings to the left by 75 degrees), and the moving speed Va of a cylinder rod is 1.339mm/s (the moving time is 22.4s when the cylinder rod moves by 30 mm);
4. continuing to rotate the mechanical zero adjusting bolt of the adjusting servo valve ③ counterclockwise until the displacement sensor ⑤ feeds back that the rod of the hydraulic cylinder ④ moves in the reverse direction (the test example is moving to the right), and recording the moving direction as B;
5. the method comprises the steps of reversely fine-tuning a servo valve ③ through a mechanical zero-position adjusting bolt (clockwise rotation is used as a test example), reducing the moving speed (rightward movement) of a hydraulic cylinder ④ in the direction B, measuring the time spent by moving a cylinder rod for multiple times by 30mm, and recording the direction Rb (clockwise), the position Lb (60 degrees towards the upper right of the long end of a wrench) and the moving speed Vb of the cylinder rod which are 1.657mm/s (18.1 s spent on moving 30 mm) of the rotating zero-position adjusting bolt when the cylinder rod moves | Vb-Va | in the direction and is less than or equal to 0.5 Va;
6. the mechanical zero position adjusting bolt of the servo valve ③ is adjusted again to the middle position (the long end of the wrench swings to the upper right by 7.5 degrees) of the position La and the position Lb, and then the adjusting bolt is locked;
7. when the hydraulic cylinder ④ runs to the stroke end, a plug of a servo valve ③ is plugged, and a button on a control panel is operated to give a control signal to control the cylinder rod of the hydraulic cylinder ④ to move to the stroke middle position;
8. the plug of the servo valve ③ is plugged, a control signal is input by operating a button, the hydraulic cylinder ④ is controlled to move a certain distance (about 5mm and defined as direction C) leftwards, the moving direction of the cylinder rod (left movement in the test) and the speed Vc are recorded after the plug of the servo valve ③ is unplugged10.865mm/s (movement of 30mm takes 34.7 s);
9. the plug of the servo valve ③ is plugged again, the control signal is input by operating the button, the hydraulic cylinder ④ is controlled to move rightwards for a certain distance (about 5mm and defined as the direction D), the plug of the servo valve ③ is unplugged, and the moving direction (rightwards in the test) and the speed Vd of the cylinder rod are recorded again10.448mm/s (it takes 66.9s to move 30 mm);
10. and (3) judging a zero setting result:
the rated flow of a servo valve used in the test loop is 4L/min, the hysteresis Hy% is 3%, the resolution Th% is 0.5%, and the size of the double-rod hydraulic cylinder is 80/56-158.
The idle load rated moving speed Ve of the hydraulic cylinder is 4L/min/[3.14/4(80mm ^2-56mm ^2) ] -26 mm/s.
Zero offset percentage Bi actually measured by servo valve after zero setting1%=|Vc1-Vd1|/2Ve=|0.865-0.448|/2/26=0.8%;
(1) When the required precision Be% of zero offset setting is in the range of Be% to Hy%/2, the zero setting process can Be simplified to the condition that the speed directions of Vc and Vd are opposite;
(2) when the zero offset setting requires the precision Be% range is Bi1When Be% is more than or equal to Be% and less than or equal to Hy%/2, the debugging meets the zero setting ending judgment condition (3), the servo valve can Be determined to end the online zero setting process, and the servo valve has zero deviation but is within the acceptable precision range;
(4) when the zero offset setting requires the precision Be% range of Be% < Bi1% this zeroing is not completed.
According to the aforementioned test results Vc1>Vd1And Vc1And (4) turning the direction to the left, referring to the step 3, continuing to fine-tune the zero adjusting bolt anticlockwise, and then repeating the steps 8-10 again. The results of the retesting are as follows: cylinder rod left movement Vc2When the moving time is 0.779mm/s (38.5 s for 30 mm), the cylinder rod moves to the right Vd2After zeroing, the servo valve measured zero offset percentage Bi at 0.498mm/s (30 mm movement takes 60.3s)2%=|Vc2-Vd2|/2Ve=|0.865-0.448|/2/26=0.54%;
And (5) judging the zero setting result again:
(5) when the zero offset setting requires the precision Be% range is Bi2%≤Be%<Bi1When% is greater than or equal to 0.6%, for example, the debugging meets the zero setting end judgment condition (3), the online zero setting process of the servo valve can Be determined to Be ended, and the servo valve has zero offset but is within the acceptable precision range;
(6) when the zero offset setting requires the precision Be% range to Be between Th% and Be% < Bi2% of the total amount of Bi ≦ Be%, for example, 0.5% for the current zeroing, and the above zeroing step is continued until Bi ≦ Be%;
(7) if the range of the zero offset setting required accuracy Be% is Be% < Th%, for example, when Be% < 0.3%, the present zero setting is not completed, and it is necessary to continue the zero setting step and determine the zero setting result in accordance with Be% < Th% < 0.5%.
The higher the resolution and repetition accuracy of the displacement sensor, the longer the sampling distance of the movement of the recording cylinder rod, and the higher the on-line zeroing accuracy.
The invention can quickly judge whether the servo valve has zero offset on line, and realize the zero-position on-line zero setting of the servo valve machinery under certain precision condition by simple operation.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (1)

1. A method for online zero adjustment of mechanical zero position of a servo valve is characterized by comprising the following steps:
1. starting a test loop, supplying oil and ensuring normal operation;
2. closing a servo valve to input a control signal, observing the moving direction of a cylinder rod of the hydraulic cylinder fed back by a displacement sensor under the no-load state of the hydraulic cylinder, and defining the moving direction as A;
3. fine-tuning a mechanical zero adjusting bolt of the servo valve, and reducing the moving speed of the cylinder rod in the direction A until the feedback speed is close to zero; recording the direction Ra, the position La and the moving speed Va of the cylinder rod of the rotating zero adjusting bolt;
4. when the hydraulic cylinder runs to the stroke end point, a control signal is manually operated or given to the servo valve, and the hydraulic cylinder is operated to move to the stroke middle position;
5. continuously adjusting the mechanical zero adjusting bolt of the servo valve along the direction until the cylinder rod moves reversely, and defining the moving direction as B;
6. when the moving speed Vb of the cylinder rod is reduced to Vb-Va which is less than or equal to 0.5Va, recording the direction Rb, the position La and the moving speed Vb of the cylinder rod of the rotating zero adjusting bolt;
7. adjusting the mechanical zero adjusting bolt of the servo valve again to the middle position of the position La and the position Lb;
8. manually operating or giving a control signal to a servo valve, operating a hydraulic cylinder to move for a certain distance, defining the hydraulic cylinder as a direction C, closing the servo valve control signal, and recording the moving speed Vc of a cylinder rod;
9. manually operating or giving a control signal to a servo valve, operating the hydraulic cylinder to move in a reverse direction for a certain distance, defining the direction D, closing the servo valve control signal, and recording the moving speed Vd of the cylinder rod;
10. zero setting end determination conditions:
in the technical parameters of the servo valve, hysteresis is recorded as Hy%, and resolution is recorded as Th%;
under the condition that a servo valve inputs a rated signal, the no-load rated moving speed of the hydraulic cylinder of the test loop is recorded as Ve;
after zero setting, recording the actually measured zero offset percentage of the servo valve as Bi%, and defining that Bi% is | Vc-Vd |/2 Ve;
the precision required by zero offset setting is recorded as Be%;
1) when the speed Vc is equal to Vd is equal to 0, the mechanical zero-position online zero-setting process of the servo valve is finished, and the servo valve can be determined to have no zero offset;
2) when the directions of the speeds Vc and Vd are opposite and one of the speeds is zero, if Bi is more than or equal to 0 and less than or equal to Th percent, the mechanical zero-position online zero setting process of the servo valve is finished, and the servo valve is determined to have no zero offset;
3) when the directions of the speeds Vc and Vd are opposite and one of the speeds is zero, if Th percent is more than or equal to Bi percent and less than or equal to Be percent, the mechanical zero position on-line zero setting process of the servo valve is finished, and the servo valve has zero deviation but is in an acceptable precision range;
4) and when the directions of the speeds Vc and Vd are opposite, but Bi% is larger than Be% or the directions of the speeds are the same, referring to the direction of the maximum moving speed of the cylinder rod and repeating the step 3 or the step 6, finely adjusting the mechanical zero position adjusting bolt of the servo valve, and repeating the steps 8-10.
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CN113446287B (en) * 2021-06-23 2024-01-05 河南航天液压气动技术有限公司 Automatic zeroing system and method for 2D reversing valve based on machine learning algorithm
CN114183334A (en) * 2021-11-03 2022-03-15 内蒙古北方重工业集团有限公司 Method for suppressing zero drift in debugging of amplification plate of radial plunger pump

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JP3600360B2 (en) * 1996-04-12 2004-12-15 三菱重工業株式会社 Servo valve zero adjustment device
CN101482131A (en) * 2008-01-08 2009-07-15 鞍钢股份有限公司 On-line equalization internal leaking electric zero-adjusting method of servo valve
JP2009275917A (en) * 2009-08-24 2009-11-26 Shimadzu Corp Air cylinder driving device
CN102297282A (en) * 2010-06-25 2011-12-28 鞍钢股份有限公司 Online zeroing method for proportional valve
CN104423320A (en) * 2013-09-10 2015-03-18 重庆长安工业(集团)有限责任公司 Automatic zero setting method of servo control system
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