Control valve cage and its manufacturing method

Control valve cage and its manufacturing method

1 is a perspective view showing a conventional control valve;

2 is a perspective view of a control valve according to an embodiment of the present invention;

3A and 3B are a perspective view and an exploded view of the cage shown in FIG. 2 ;

<Explanation of symbols for main parts of the drawing>

100...control valve 200...body

210...actuator 300...valve body

310...valve seat 400...plug

410...valve stem 500...cage

510...flow hole

<backgroundart><p>The present invention relates to a control valve, and more particularly, by arranging a flow hole in a cage through which a fluid flows, the flow rate characteristic of the fluid passing through it is formed to be close to the target curve of the exponential flow control (EQ%) characteristic. It relates to a method for manufacturing a cage for a control valve.</p><p>In general, the control valve can be divided into plug throttling trims and port throttling trims according to the shape of the trim.</p><p>Here, the plug throttling trim is composed of a seat and a cage to control the flow rate according to the shape of the plug, and is mainly used where the size of the valve is small and the flow rate control is general.</p><p>In addition, the port throttling trim is mainly applied to valves that are relatively larger than the plug throttling trim, and the flow rate is adjusted according to the size and shape of the flow hole formed in the cage. The structure shown in FIG. 1 is generally used. .</p><p>Referring to the drawings, the conventional control valve 10 has an actuator 20 connected to a control unit (not shown), and a connection passage is formed in the upper part and is connected to the actuator 20 in the lower part, and the fluid flows therein. A body 30 is provided.</p><p>And a stem 40 connected to the actuator 20, a plug 50 connected to the stem 40 and transferred up and down, and provided inside the body 30, the center is penetrated to form a fluid passage A valve seat 60 is provided.</p><p>In addition, a plurality of overlapping with a central penetration state, provided in the connection passage of the body 30, the plug 50 is transferred to the central through hole, and a plurality of flow holes 71 are formed on the outside of the cage ( 70) is provided.</p><p>Here, the plurality of flow holes 71 formed outside the cage 70 are arranged in a state having a predetermined size and a predetermined interval.</p><p>In the control valve 10, when the fluid flows into the body 30, the plug 50 operated by the actuator 20 is moved up and down, and a space is formed between the valve seat 60 and the fluid. will move</p><p>Here, the fluid passing through the space between the plug 50 and the valve seat 60 has a flow rate according to the opening degree of the flow hole 71 formed in the cage 70 by the vertical movement of the plug 50 . will be regulated</p><p>However, in the conventional control valve 10, a predetermined number of holes or a predetermined angle are distributed at a position where the flow holes 71 formed on the outside of the cage 70 in which the flow rate is controlled are opened, and between the flow holes 71 . As the gap is formed to be larger than the diameter of the flow hole 71, the change in flow rate is irregular and a problem occurs that precise flow control cannot be performed.</p><p>In order to solve some of these problems, in the case of manufacturing the conventional control valve, the control valve has been manufactured by adjusting the diameter and position of the flow hole of the cage through several experiments.</p><p>However, designing the position and diameter of the flow hole of the cage through several experiments every time the valve is manufactured causes a problem that not only the efficiency of the operation is considerably reduced, but also the time required is long.</p><p>Accordingly, in the case of a control valve having a linear type of flow characteristic, data is obtained through several repeated experiments depending on the body structure and type of trim, and a number of experiments are performed every time by using this data to produce a control valve. Without implementation, the control valve is produced.</p><p>However, the control valve having exponential flow characteristics cannot use the linear type experimental results as it is, and the uncertainty of flow rate change according to the flow hole arrangement of the cage is significant depending on the exponential function characteristics. A problem arises in that it is necessary to manufacture a control valve having appropriate flow characteristics through repeated experiments.</p></backgroundart><abstractproblem><p>The present invention was created to solve the above problems, and it is an object of the present invention to provide a method for manufacturing a cage for a control valve that is suitable for valve flow characteristics and has precise flow control characteristics while reducing trial and error in the design stage. .</p><p>Other objects and advantages of the present invention will be set forth below and will be learned by way of example of the present invention. Further, the objects and advantages of the present invention may be realized by means and combinations indicated in the claims.</p></abstractproblem>

<p>The method for manufacturing a cage for a control valve of the present invention for achieving the above object is provided inside a valve body through which a fluid flows, and a plurality of flow holes are provided on the outside in a cylindrical shape to move up and down the plug in n-divided positions. A method for manufacturing a cage of control valves sequentially arranged so that the flow rate is adjusted according to the degree of opening/closing according to calculating a flow coefficient (Cv) according to the specification of the control valve; The total cross-sectional area (A) of the flow holes formed in the cage using the number of flow holes at the bottom of the cage and the flow coefficient (Cv)<sb>max</sb>) to calculate; a cage dividing step of dividing the cage into n equal parts in the longitudinal direction; and the total cross-sectional area Am = A of all flow holes from the lower side to the mth division position among the n division positions of the cage division step.<sb>max </sb>е<sp>c(x-1)</sp> and a flow hole forming step of forming a plurality of m-th flow holes.</p><p>Here, it is preferable to form at least three or more flow holes at the lowermost side of the cage to prevent cavitation or flushing that causes damage to the valve.</p><p>And the flow hole, the flow hole formed in the m-th equal position and the m-th<sb>+1</sb>It is preferable that the interval between the flow holes formed at the second equal position has a value smaller than the sum of the radii of each flow hole, and is formed in a spiral direction with respect to the longitudinal direction of the cage.</p><p>Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.</p><p> Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.</p><p> Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention and do not represent all the technical spirit of the present invention, It should be understood that there may be water and variations.</p><p>2 is a perspective view showing a control valve according to a preferred embodiment of the present invention.</p><p>Referring to the drawings, the control valve 100 according to a preferred embodiment of the present invention includes a main body 200 provided with a control unit (not shown), and an actuator 210 coupled to the upper portion of the main body 200, , the lower body 200 is provided with a valve body (300).</p><p>In addition, a plug 400 connected to the actuator 210 and the valve stem 410 is provided, and a cage 500 through which the plug 400 is transported is provided.</p><p>The body 200 is a member that opens and closes the fluid flow of the control valve 100 and controls the flow rate.</p><p>The main body 200 is provided with a control unit for controlling the fluid flow and flow rate of the control valve 100 on one side, and an actuator 210 operated under the control of the control unit is provided on the upper side.</p><p>The valve body 300 is a member through which a fluid flows by forming an internal space, and a valve seat 310 is provided therein so that the fluid flows.</p><p>And an inlet through which the fluid flows into the inner space is formed on one side of the valve body 300, and an outlet through which the fluid introduced into the inner space is discharged is formed on the other side.</p><p>The plug 400 is a member that blocks or opens the flow of the fluid flowing into the valve body 300 .</p><p>The plug 400 is connected to the actuator 210 by a valve stem 410 to move up and down.</p><p>Here, one end of the plug 400 opens and closes the flow of the fluid while being moved up and down according to the operation of the actuator 210 and contacted or spaced apart from the valve seat 310 .</p><p>The cage 500 is a member that controls the flow rate of the fluid flowing into the valve body 300 .</p><p>The cage 500 has a cylindrical shape with both ends open, and the plug 400 is moved up and down to the penetrating center of the cage 500 while being inserted into the valve body 300 .</p><p>In addition, a plurality of flow holes 510 forming a flow path so that the fluid flowing into the valve body 300 passes is formed on the outside of the cage 500 at n-divided positions in the longitudinal direction.</p><p>Accordingly, the fluid flowing inside the valve body 300 opens or blocks the flow hole 510 of the cage 500 according to the vertical movement of the plug 400 to adjust the flow rate.</p><p>Here, a method of manufacturing the cage 500 of the control valve 100 will be described as follows.</p><p>First, the number of the lowermost flow holes 510 of the cage 500 is selected. As shown in FIGS. 3A and 3B , five flow holes 510 are formed.</p><p>At this time, the number of the flow holes 510 of the cage 500 is not limited to five, but it is preferable to form at least three or more so that cavitation or flushing that causes damage to the valve does not occur.</p><p>Then, the flow coefficient (Cv) according to the control valve is determined.</p><p>In this embodiment, the control valve 100 was selected as a severe type (type) of 4" with 2-1/2", and accordingly, the flow coefficient Cv was determined to be 82.</p><p>Here, the total cross-sectional area of the flow holes using the number of flow holes 510 at the bottom of the cage 500 (3S, 4S, 5S, 6S) and the data representing the exponential flow rate characteristic with the flow coefficient (Cv) (A<sb>max</sb>) is calculated.</p><p>Therefore, since the flow holes of this embodiment were formed in five, 5S A Group shown in the table below; Select the diagram of y = 0.0402x-13.252 and substitute the flow coefficient (Cv) 82, which is the y item, to the total cross-sectional area (A) of the flow hole 510, which is the x item.<sb>max</sb>) 2369.45 is calculated.</p><p><img file="KR100856495B1_D0001.tif" /></p><p>And the cage 500 is divided into n equal parts in the longitudinal direction, and in this embodiment, it is formed into 10 equal parts as shown in FIG. 3B .</p><p>Here, in the present embodiment, equal parts dividing the cage 500 may be changed according to the standard of the control valve.</p><p>Then, in the division step of the cage 500, the total cross-sectional area (Am) of all flow holes from the lower side to the m-th equally divided positions among the positions divided into 10 equal parts, Am = A, which is an exponential function<sb>max</sb><sb></sb>е<sp>c(x-1)</sp>is used to form a plurality of flow holes at the m-th equally divided positions.</p><p>Here, c of the total cross-sectional area (Am) denotes a constant, and is selected as 4 in this embodiment, and it should be understood that it may be changed according to the flow characteristics of the control valve.</p><p>And the flow hole of the cage 500 indicates the degree of opening in the closed position step by step, and the opening step (x) according to the degree of opening is expressed as a percentage (%).</p><p>Accordingly, when the lowermost flow hole is opened in a state in which the cage 500 is divided into 10 equal parts, the total cross-sectional area A of the cage 500 is<sb>max</sb>) 2369.45, the exponential function Am = A<sb>max</sb><sb></sb>е<sp>4(x-1) </sp> In the opening step (x), the total cross-sectional area (A) of all flow holes up to the first equalization position by substituting 0.1, which is 10% of the opening degree,<sb>1</sb>) 64.74219 is calculated.</p><p>and the total cross-sectional area of all flow holes up to the first equalization position (A<sb>1</sb>) according to the number of holes, each cross-sectional area of the flow hole 510 of the cage 500 that is first opened comes out, and the diameter according to each cross-sectional area is calculated.</p><p>Here, the total cross-sectional area (Am) of all flow holes up to the m-th equally divided position of the cage 500 is the total cross-sectional area (A) of the flow holes formed at the first equally divided position (A).<sb>1</sb>') to the total cross-sectional area (Am') of the flow holes formed at the m-th equally divided position.</p><p>That is, the total cross-sectional area (Am) of all flow holes up to the mth equidistant position is Am = (A<sb>1</sb>'+ A<sb>2</sb>'+ A<sb>3</sb>'+...+ Am').</p><p>Accordingly, the total cross-sectional area (Am) of the flow holes formed at the m-th equal parts of the cage 500 is Am=Am(Am).<sb>-1</sb>) is indicated.</p><p>Here, the total cross-sectional area (A) of all flow holes up to the first equalization position (A<sb>1</sb>) is calculated as 64.74219, and 0.2, which is 20% of the opening degree (x) of the second equidistant position, is calculated using the above exponential formula Am = A<sb>max</sb><sb></sb>е<sp>4(x-1)</sp>Substituting into , the total cross-sectional area of all flow holes up to the second equalization position (A<sb>2</sb>) 96.5840mm2 is calculated.</p><p>Therefore, the total cross-sectional area (A) of all flow holes up to the second equalization position (A<sb>2</sb>) Total cross-sectional area (A) of all flow holes from 96.5840 to the first equalization position of the previous stage (A)<sb>1</sb>) Total cross-sectional area (A) of the flow hole formed at the second equal position by subtracting 64.74219<sb>2</sb>') 31.8418 is calculated.</p><p>Similarly, if 0.3, which is 30% of the opening degree (x) of the third equalization position, is calculated by substituting the exponential function formula above, the total cross-sectional area (A) of all flow holes up to the third equalization position<sb>3</sb>) 114.0864 is calculated.</p><p>Then, the total cross-sectional area (A) of all flow holes up to the second bisecting position (A<sb>2</sb>) Subtracting 96.5840, the total cross-sectional area of the flow hole formed at the third equal position (A<sb>3</sb>') 47.5024 is calculated.</p><p>Here, the interval between the flow holes 510 is the m-th flow hole and m<sb>+1</sb>It has a value smaller than the sum of the respective radii of the second flow hole, and is formed in a spiral direction with respect to the longitudinal direction of the cage 500 .</p><p>In this way, the control valve 100 selects the number of flow holes formed on the outside of the cage 500, forms the flow holes 510, and opens the flow holes 510 in stages to obtain the same flow control characteristics as the exponential function. can indicate</p><p>In addition, the control valve 100 may prevent cavitation or flushing from occurring by forming three or more lowermost flow holes.</p>

<p>As described above, according to the method for manufacturing a cage for a control valve according to the present invention, the following effects are provided.</p><p>By forming a cage flow hole of a control valve with exponential flow characteristics using the previously secured flow characteristics data of linear type valves, it is not necessary to test a control valve whose flow characteristics are close to exponential flow control characteristics. It can be produced in a simple way.</p><p>Accordingly, it is possible to improve the working efficiency of the control valve having an exponential flow rate characteristic, and the production process time is greatly shortened.</p><p>As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto, and the technical spirit of the present invention and the following by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various modifications and variations are possible within the equivalent scope of the claims to be described.</p>