Control loop for improving stable operation of servo valve

Abstract

The invention provides a control loop for improving stable operation of a servo valve. Comprising a first pipeline, a second pipeline and a third pipeline, a first outlet of the first pipeline is connected with an inlet of the filter, and an outlet of the filter is connected with an inlet of the servo valve; a second outlet of the first pipeline is connected with an inlet of the hydraulic control one-way valve, an outlet of the hydraulic control one-way valve is connected with an inlet of the servo valve, and an outlet of the servo valve is connected with a rodless cavity of the APC oil cylinder; a third outlet of the first pipeline is connected with an inlet of a reversing valve, and an outlet of the reversing valve is connected with an inlet of a hydraulic control one-way valve; the filter is connected with the pressure reducing valve, and oil liquid firstly enters the pressure reducing valve and then enters the filter. The method is easy to implement, the pilot oil pressure of the servo valve can be adjusted and controlled without changing an original hydraulic valve block, and the method is a practical method for solving the problem that the pilot oil pressure of the servo valve is too high, so that the servo valve explodes and leaks oil.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic control in metallurgical industry, and in particular to a control loop for improving the stable operation of a servo valve. Background Art

[0002] The roughing mill is one of the key equipment of the main rolling line of hot rolling. The control circuit of the rolling mill usually adopts the control mode of electric pressing control (EGC) + hydraulic roll gap control (HGC). The function of the hydraulic pressing APC (hydraulic position automatic control system) of the rolling mill is to roll the slab from 230mm thickness to the thickness required by the finishing mill. The hydraulic APC of the rolling mill uses a servo system to control the position and pressure of the pressing. The system has the advantages of fast dynamic response and high control accuracy. It can control the roll gap in real time during slab rolling to make the thickness of the rolled slab consistent. The rolling mill frame is equipped with two APC hydraulic cylinders, which are installed on the upper part of the rolling mill frame. The APC hydraulic cylinder is closed-loop controlled by a servo valve, which only controls the pressure on the side of the hydraulic cylinder plug. The oil pressure of the hydraulic cylinder is provided by the servo hydraulic system of the rolling mill. The servo hydraulic system of the rolling mill is equipped with an accumulator to ensure the stability of the hydraulic system pressure. The rod side of the hydraulic cylinder is controlled by a proportional pressure reducing valve and connected to a separate low-pressure buffer accumulator line to absorb hydraulic shocks and avoid vacuum.

[0003] The existing hot rolling production line rolling mill hydraulic pressure control system has a designed working pressure of 29Mpa. There is no pressure detection element in the control oil circuit. After normal production, the servo valve blows frequently. The servo valve model is: D662Z434KP01JOMF6VSX2-A. The servo valve blows up at the control oil filter element position. After the servo valve blows up, it causes oil leakage in the hydraulic system and hydraulic pressure failure, which causes production interruption and scrap steel, causing great damage to the production line. Summary of the invention

[0004] According to the above technical problem of servo valve explosion in the existing hydraulic pressure control system, a control circuit for improving the stable operation of the servo valve is provided. The present invention mainly solves the servo explosion problem by adding a pressure reducing valve to adjust and reduce the control oil pressure.

[0005] The technical means adopted by the present invention are as follows:

[0006] A control loop for improving the stable operation of a servo valve, characterized by comprising: a first pipeline, a second pipeline and a third pipeline;

[0007] The first outlet of the first pipeline is connected to the inlet of the filter, and the outlet of the filter is connected to the inlet of the servo valve; the second outlet of the first pipeline is connected to the inlet of the hydraulically controlled one-way valve, and the outlet of the hydraulically controlled one-way valve is connected to the inlet of the servo valve, and the outlet of the servo valve is connected to the rodless chamber of the APC cylinder; the third outlet of the first pipeline is connected to the inlet of the reversing valve, and the outlet of the reversing valve is connected to the inlet of the hydraulically controlled one-way valve; the fourth outlet of the first pipeline is connected to the inlet of the proportional pressure reducing valve, and the outlet of the proportional pressure reducing valve is connected to the rod chamber of the APC cylinder;

[0008] The first outlet of the second pipeline is connected to the inlet of the servo valve, and the second outlet of the second pipeline is connected to the inlet of the proportional pressure reducing valve.

[0009] The first outlet of the third pipeline is connected to the inlet of the hydraulically controlled one-way valve, the second outlet of the third pipeline is connected to the inlet of the reversing valve, and the third outlet of the third pipeline is connected to the inlet of the proportional pressure reducing valve;

[0010] The filter is connected to the pressure reducing valve, and the oil first enters the pressure reducing valve and then enters the filter.

[0011] Furthermore, the pressure reducing valve is a direct-acting pressure reducing valve.

[0012] Furthermore, the model of the pressure reducing valve is DR6DP2-5X / 315YM.

[0013] Furthermore, the pressure reducing valve and the filter are connected through a valve block, the valve block is a rectangular structure, an oil inlet hole and an oil outlet hole are arranged on the lower surface of the valve block, valve block fixing bolt holes are arranged on the lower surface of the valve block on both sides of the oil inlet hole and the oil outlet hole, a pressure reducing valve fixing bolt hole is arranged on the front surface of the valve block, and a filter fixing bolt hole is arranged on the rear surface of the valve block.

[0014] Furthermore, the first pipeline is connected to the first outlet, the second outlet, the third outlet and the fourth outlet respectively through ball valves.

[0015] Furthermore, a stop valve is provided on the first pipeline, and check valves are provided on the second pipeline and the third pipeline.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The present invention solves the problem of hydraulic servo valve explosion in the rough rolling mill, reduces production interruption, scrap steel and hydraulic system oil leakage caused by servo valve explosion in the rough rolling mill, and ensures the normal service life of the servo valve. The device does not need to re-process and manufacture the entire hydraulic control valve block, but only needs to process a small valve block and install it on the original valve block. It is simple to make and has low improvement cost, greatly reducing downtime, increasing effective production operation time, and reducing maintenance and spare parts costs, which has brought great effects on cost reduction and efficiency improvement for enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 This is the control loop diagram of the present invention.

[0020] Figure 2 This is a structural diagram of the valve block of the present invention.

[0021] In the figure: 1. First pipeline; 2. Second pipeline; 3. Third pipeline; 4. Filter; 5. Servo valve; 6. Hydraulic control one-way valve; 7. APC cylinder; 8. Reversing valve; 9. Proportional pressure reducing valve; 10. Oil inlet hole; 11. Oil outlet hole; 12. Valve block fixing bolt hole; 13. Pressure reducing valve fixing bolt hole; 14. Pressure reducing valve. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0026] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the control circuits or components referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0027] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0028] like Figure 1 As shown, the present invention provides a control circuit for improving the stable operation of a servo valve, characterized in that it comprises: a first pipeline 1, a second pipeline 2 and a third pipeline 3;

[0029] The first outlet of the first pipeline is connected to the inlet of the filter 4, and the outlet of the filter is connected to the inlet of the servo valve 5; the second outlet of the first pipeline is connected to the inlet of the hydraulically controlled one-way valve 6, and the outlet of the hydraulically controlled one-way valve is connected to the inlet of the servo valve, and the outlet of the servo valve is connected to the rodless chamber of the APC cylinder 7; the third outlet of the first pipeline is connected to the inlet of the reversing valve 8, and the outlet of the reversing valve is connected to the inlet of the hydraulically controlled one-way valve; the fourth outlet of the first pipeline is connected to the inlet of the proportional pressure reducing valve 9, and the outlet of the proportional pressure reducing valve is connected to the rod chamber of the APC cylinder;

[0030] The first outlet of the second pipeline is connected to the inlet of the servo valve, and the second outlet of the second pipeline is connected to the inlet of the proportional pressure reducing valve;

[0031] The first outlet of the third pipeline is connected to the inlet of the hydraulically controlled one-way valve, the second outlet of the third pipeline is connected to the inlet of the reversing valve, and the third outlet of the third pipeline is connected to the inlet of the proportional pressure reducing valve;

[0032] The filter is connected to the pressure reducing valve 14, and the oil first enters the pressure reducing valve and then enters the filter.

[0033] The pressure reducing valve is connected to the filter through a valve block. The valve block is a rectangular parallelepiped structure. An oil inlet hole 10 and an oil outlet hole 11 are arranged on the lower surface of the valve block. Valve block fixing bolt holes 12 are arranged on the lower surface of the valve block on both sides of the oil inlet hole and the oil outlet hole. Pressure reducing valve fixing bolt holes 13 are arranged on the front surface of the valve block. Filter fixing bolt holes are arranged on the rear surface of the valve block.

[0034] The invention of the method firstly installs a pressure transmitter at the pressure measuring point of the APC hydraulic valve station control oil circuit, and connects the pressure sensor signal to the PDA system, and the PDA system automatically collects the pressure. The collected servo valve control oil pressure curve is analyzed through the curve. The maximum pressure of the servo valve control oil pressure reaches 39MPa during normal operation. According to the servo valve model, it is found that the maximum allowable working pressure of the servo valve is 35MPa. The control oil circuit pressure of the servo valve exceeds the designed maximum pressure value during normal operation. The servo valve is fatigued and exploded due to long-term operation under the pressure exceeding the designed value. Finally, the real reason for the servo valve explosion is analyzed.

[0035] Secondly, based on the cause of the servo valve explosion and damage, improvement measures are proposed. A pressure reducing valve is added to the control oil circuit before the servo valve to reduce the control oil pressure and solve the problem of servo valve explosion caused by excessive control oil pressure.

[0036] Finally, considering that the addition of a new pressure reducing valve in the control circuit requires redesigning and processing the entire hydraulic valve block, and the cost of replacing the valve block is high, the study adopts a redesigned small valve block device that installs the pressure reducing valve and the original filter together to achieve the function of controlling oil pressure reduction without replacing the original valve block.

[0037] The device solves the problem of hydraulic servo valve explosion in the rough rolling mill, reduces production interruption, scrap steel and hydraulic system oil leakage caused by servo valve explosion in the rough rolling mill, and ensures the normal service life of the servo valve. The device does not need to re-process and manufacture the entire hydraulic control valve block, but only needs to process a small valve block and install it on the original valve block. It is simple to make and has low improvement cost, which greatly reduces downtime, increases effective production operation time, reduces maintenance and spare parts costs, and brings great effects to the company's cost reduction and efficiency improvement.

[0038] Independently developed and implemented, the present invention has been put into use in a rough rolling unit of a 2050mm hot rolling line in a certain factory. After long-term actual operation, it has fully achieved the expected technical effect.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control circuit for improving the stable operation of a servo valve, characterized in that: include: A first pipeline, a second pipeline and a third pipeline; The first outlet of the first pipeline is connected to the inlet of the filter, and the outlet of the filter is connected to the inlet of the servo valve; The second outlet of the first pipeline is connected to the inlet of the hydraulically controlled one-way valve, the outlet of the hydraulically controlled one-way valve is connected to the inlet of the servo valve, and the outlet of the servo valve is connected to the rodless chamber of the APC cylinder; the third outlet of the first pipeline is connected to the inlet of the reversing valve, the outlet of the reversing valve is connected to the inlet of the hydraulically controlled one-way valve; the fourth outlet of the first pipeline is connected to the inlet of the proportional pressure reducing valve, and the outlet of the proportional pressure reducing valve is connected to the rod chamber of the APC cylinder; The first outlet of the second pipeline is connected to the inlet of the servo valve, and the second outlet of the second pipeline is connected to the inlet of the proportional pressure reducing valve; The first outlet of the third pipeline is connected to the inlet of the hydraulically controlled one-way valve, the second outlet of the third pipeline is connected to the inlet of the reversing valve, and the third outlet of the third pipeline is connected to the inlet of the proportional pressure reducing valve; The filter is connected to the pressure reducing valve, and the oil first enters the pressure reducing valve and then enters the filter.

2. The control circuit for improving the stable operation of the servo valve according to claim 1, characterized in that: The pressure reducing valve is a direct-acting pressure reducing valve.

3. The control circuit for improving the stable operation of a servo valve according to claim 1, characterized in that: The model of the pressure reducing valve is DR6DP2-5X / 315YM.

4. The control circuit for improving the stable operation of a servo valve according to claim 1, characterized in that: The pressure reducing valve is connected to the filter through a valve block. The valve block is a rectangular structure. An oil inlet hole and an oil outlet hole are arranged on the lower surface of the valve block. Valve block fixing bolt holes are arranged on the lower surface of the valve block on both sides of the oil inlet hole and the oil outlet hole. Pressure reducing valve fixing bolt holes are arranged on the front surface of the valve block. Filter fixing bolt holes are arranged on the rear surface of the valve block.

5. The control circuit for improving the stable operation of a servo valve according to claim 1, characterized in that: The first pipeline is connected to the first outlet, the second outlet, the third outlet and the fourth outlet respectively through ball valves.

6. The control circuit for improving the stable operation of a servo valve according to claim 1, characterized in that: The first pipeline is provided with a stop valve, and the second pipeline and the third pipeline are provided with check valves.

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