Valve box cutting machine

Abstract

To provide a valve box cutting machine that can easily cut a valve box in a short time without generating chips.SOLUTION: A valve box cutting machine, which cuts a valve box which is a constitutive member of a valve and comprises a pair of joint parts and a boss part provided between the joint parts and in which a flow path for liquid is formed, comprises: a placement base which contacts a boss part of the valve box to be cut to place the box thereon; a cutting blade that stands by at a position above the placement base; pressing means that presses the cutting blade toward the placement base; and a side wall, formed around the placement base, which holds the pair of joint parts of the valve box placed on the placement base and guides the cutting blade downward. The cutting blade falls down along the side wall while being pressed toward the placement base to apply shear force to the valve box placed on the placement base to press-cut the valve box.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a valve body cutting machine for cutting valve bodies that constitute valves used in nuclear power plants. [Background technology]

[0002] At nuclear power plants, pipes and valves used to transport contaminated materials, including radioactive materials, are sometimes removed. Depending on the level of radioactive contamination in the pipes and valves to be removed, they may be subject to a clearance system and may be able to be reused or disposed of in the same way as general waste materials. Therefore, it is necessary to measure the level of radioactive contamination in the pipes and valves and to decontaminate the inner surfaces of the pipes and valves. As a pre-process for this, a device that cuts the pipes along their longitudinal direction has been proposed (Patent Document 1).

[0003] The device disclosed in Patent Document 1 includes a first blade portion and a second blade portion, and the first blade portion moves relatively along the longitudinal direction of the pipe while contacting the outer diameter side of the pipe. As a result, the first blade portion bites into the pipe from the outer diameter side toward the inner diameter side, and stress is concentrated in the inner diameter direction on the outer diameter side of the pipe by the first blade portion, causing the outer diameter side of the pipe to be crushed and plastically deformed, forming a biting portion along the longitudinal direction. The second blade portion moves relatively along the longitudinal direction of the pipe while contacting this biting portion from the inner diameter side of the pipe. As a result, the auxiliary second blade portion can cut the portion that could not be completely cut by the first blade portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-24043 Summary of the Invention [Problem to be solved by the invention]

[0005] The tool in Patent Document 1 can cut piping, but cannot cut valve bodies. Conventionally, thick valve bodies have often been cut using thermal cutting such as a lance or a band saw. However, at nuclear power plants, thermal cutting is limited from the perspective of fire protection, and cutting valve bodies using mechanical cutting such as a band saw takes time and cannot cut through the welded layer (Stellite) inside the valve body. Furthermore, cutting with a band saw generates chips, which may cause contaminated dust to scatter.

[0006] In view of the above problems, the present invention provides a valve body cutting machine that can easily cut a valve body in a short time without generating chips. [Means for solving the problem]

[0007] The valve box cutting machine of the present invention is a valve box cutting machine that cuts a valve box, which is a component of a valve and has a pair of joints and a boss portion provided between the joints, and has a liquid flow path formed inside.The machine comprises a mounting base on which the valve box to be cut is placed by abutting against the boss portion of the valve box, a cutting blade that waits at a position above the mounting base, a pressing means that presses the cutting blade toward the mounting base, and side walls that are provided around the mounting base and clamp the pair of joints of the valve box placed on the mounting base and guide the cutting blade downward.The cutting blade falls along the side walls while being pressed toward the mounting base, thereby applying a shear force to the valve box placed on the mounting base and press-cutting the valve box.

[0008] According to the valve body cutting machine of the present invention, the boss portion of the valve body is supported on a mounting table, and the pair of joint portions face the respective side walls. That is, a shear force is applied to the valve body from the bottom side opposite the boss portion, and the valve body is press-cut and cut in half.

[0009] In the above-mentioned configuration, the tip side of the cutting blade may be V-shaped in front view, narrowing toward the mounting table side. In this case, the cutting blade may further have a V-shaped portion at the center in the width direction of the cutting blade. A thickened portion may be provided extending along the movement direction. By providing this thickened portion, the contact resistance between the valve body and the cutting blade can be reduced, and the valve body can be cut more reliably.

[0010] The tip side of the cutting blade may be M-shaped in front view, and the apex of a convex portion forming the center of the M-shape and projecting toward the mounting table may be located above the tip ends of both widthwise edges of the cutting blade. This allows the tip to press each joint portion while the convex portions cut the valve box from the bottom, and allows for stable cutting without the valve box shifting during cutting.

[0011] In the above configuration, the cutting blade has a tapered portion formed at the tip end that narrows toward both ends in the thickness direction, and the tapered portion is composed of a first tapered portion and a second tapered portion that forms the tip end of the cutting blade below the first tapered portion, and the inclination angle of the second tapered portion can be made larger than the inclination angle of the first tapered portion. This increases the strength of the second tapered portion, which comes into contact with the valve box first and receives the greatest impact, making it easier for the cutting blade to penetrate into the valve box at the first tapered portion.

[0012] In the above configuration, the side wall may be open around the periphery of the mounting table in a direction facing the cutting blade, thereby ensuring a clearance for the cut valve box and preventing damage to the cutting blade even if the cutting portion of the valve box opens away from the cutting blade while the cutting blade is cutting the valve box.

[0013] The valve body may have an inner diameter of 50 mm or less and be used in a nuclear power plant, and may be cut as a preliminary process to remove contaminants adhering to the inside of the valve body. Because nuclear power plants have many small-diameter valve bodies with an inner diameter of 50 mm or less, and many of them contain contaminants, the use of the valve body cutting machine of the present invention, which can automatically cut the valve body, is particularly suitable. [Effects of the Invention]

[0014] In the valve box cutting machine of the present invention, a shear force is applied to the valve box from the bottom of the valve box opposite the boss portion, and the valve box is press-cut and cut in half, so that the valve box can be cut easily in a short time without generating chips. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a simplified front view of a valve body cutter of the present invention. [Figure 2] FIG. 2 is a perspective view of the valve body cutting machine. [Figure 3] FIG. 3 is a front view of the valve body to be cut by the valve body cutting machine. [Figure 4] 1A to 1D show a cutting blade that constitutes the valve body cutting machine, in which (a) is a plan view, (b) is a front view, (c) is a side view, and (d) is an enlarged view of a main part. [Figure 5] 10A and 10B show a cutting blade constituting a valve body cutting machine of a second embodiment, in which FIG. 10A is a plan view and FIG. [Figure 6] FIG. 10 is a front view showing a cutting blade that constitutes a third valve body cutting machine. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

[0017] The valve body cutting machine of the present invention is shown in Figure 1. The valve body cutting machine of this embodiment includes a mounting table 1 on which a valve body B to be cut is placed, a cutting blade 2 that stands by at a position separated from the mounting table 1 (at an upper position), a pressing means 3 that presses the cutting blade 2 toward the mounting table, and a side wall 4 provided around the mounting table 1.

[0018] The valve body B to be cut in this embodiment is a component of a valve that connects piping used to circulate contaminated materials, including radioactive materials, in, for example, a nuclear power plant. A valve comprises basic components such as a valve body, a valve stem, and a valve disc. Of the valve components, only the valve body B (see FIG. 3), which has a liquid flow path formed inside, is removed and cut. Nuclear power plants have many valves equipped with valve bodies that have a relatively small inner diameter (the diameter of the part where the flow path is formed) of 50 mm or less. The valve body cutting machine of this embodiment is suitable for cutting so-called small-diameter valve bodies with an inner diameter of 50 mm or less, and is used as a pre-process for removing contaminants adhering to the inside of the valve body.

[0019] Valve box B constitutes a so-called globe valve, and as shown in Figure 3, has a pair of joints 11, 12 that are connected to a pipe not shown, a valve body not shown is housed between joints 11, 12, and bosses 13 that open vertically to each of joints 11, 12. An upper surface 14 of boss 13 is substantially flat, while a bottom 15 of valve box B protrudes in an arc shape.

[0020] 1 and 2, the mounting table 1 is placed approximately in the center of a flat base 10. The mounting table 1 is made of a steel material with a flat rectangular top surface in a plan view. An upper surface 14 of a boss portion 13 of the valve box B abuts against the top surface of the mounting table 1.

[0021] As shown in Fig. 4(a), the cutting blade 2 is a plate-shaped steel material with a blade thickness of 10 to 30 mm. The cutting blade 2 advances (descends) or retreats (rises) relative to the table as shown by the arrows in Fig. 1 by a pressing means 3 described later. As shown in Fig. 4(b), the tip of the cutting blade 2 has a V-shape that narrows toward the table when viewed from the front. As shown in FIG. 4(c), tapered portions 16 are formed, which narrow at both ends in the thickness direction. As shown in FIG. 4(d), the tapered portion 16 is composed of a first tapered portion 16a and a second tapered portion 16b that is located below the first tapered portion 16a and forms the tip of the cutting blade 2. In the first tapered portion 16a, the angle α formed by the pair of tapered surfaces 16a1 and 16a2 is, for example, 20° to 30°, and in the second tapered portion 16b, the angle β formed by the pair of tapered surfaces 16b1 and 16b2 is, for example, 60°. In other words, by making the inclination angle of the second tapered portion 16b larger than the inclination angle of the first tapered portion 16a, the second tapered portion 16b, which first comes into contact with the valve box B and receives the greatest impact, has increased strength, making it easier for the cutting blade 2 to penetrate the valve box B via the first tapered portion 16a.

[0022] The pressing means 3 includes a hydraulic cylinder 17 and a control unit 18. The hydraulic cylinder 17 is mechanically connected to the cutting blade 2, and presses the cutting blade 2 downward or moves it back upward with a press pressure of 500 tons or less. The control unit 18 controls the hydraulic cylinder 17 to output a pressure (a pressure suitable for cutting a small-diameter valve body B), and is controlled by a computer (not shown) (computer-controlled).

[0023] Here, a computer is basically composed of input means with input functions, output means with output functions, memory means with storage functions, calculation means with calculation functions, and control means with control functions. The input function is used to read information from outside into the computer, and the read data and programs are converted into signals in a format suitable for the computer system. The output function is used to display calculation results and stored data externally. The memory means stores and saves programs, data, and processing results. The calculation function calculates, compares, and processes data according to program instructions. The control function interprets program instructions and issues instructions to each means, and this control function oversees all of the computer's means. Input means include keyboards, mice, tablets, microphones, joysticks, scanners, capture boards, etc. Output means include monitors, speakers, printers, etc. Memory means include memory, hard disks, CDs, CD-Rs, PDs, and MOs. Calculation means include CPUs, etc., and control means include CPUs and motherboards, etc.

[0024] The side wall 4 is installed on the base 10 and extends vertically so that a pair of steel plates 4a, 4b face the mounting base 1. An opening (opening 20) is formed around the mounting base 1 in a direction facing the cutting blade 2 (a direction perpendicular to the paper surface in FIG. 1). A guide mechanism 5, as shown in FIG. 2, allows the steel plates 4a, 4b to open and close horizontally. This configuration allows the side wall 4 to guide the cutting blade 2 downward and to clamp the joints 11, 12 of the valve box B mounted on the mounting base 1. Furthermore, by providing the opening 20, even if the cutting portion of the valve box B opens away from the cutting blade 2 while the cutting blade 2 is cutting the valve box B, the opening 20 provides a clearance for the cut valve box B, preventing damage to the cutting blade 2.

[0025] Next, we will explain how to cut a valve box using this valve box cutting machine. First, as shown in Figure 1, the top surface 14 of the boss portion 13 of the valve box B is placed against the mounting base 1. This positions the bottom portion 15 of the valve box B upward. Next, the guide mechanism 5 of the side wall 4 slides the steel plates 4a and 4b horizontally, bringing the joint portions 11 and 12 into contact with the side wall 4, respectively. This clamps the joint portions 11 and 12 between the side wall 4, and the joint portions 11 and 12 of the valve box B are fixed in place.

[0026] Thereafter, the control unit 18 controls the hydraulic cylinder 17 to output a pressure force, causing the cutting blade 2 to fall along the side wall 4 while being pressed toward the mounting base. When the tip (second tapered portion 16b) of the cutting blade 2 reaches the valve box B placed on the mounting base 1, the cutting blade 2 applies a shearing force to press-cut the valve box B. That is, the valve box B is subjected to a shearing force from the valve box bottom 15 on the opposite side from the boss portion 13, and is press-cut and cut in half. At this time, the joints 11 and 12 are supported by the side wall 4, and even if the cut portion of the valve box B opens away from the cutting blade 2 while the cutting blade 2 is cutting the valve box B, a relief portion for the cut valve box B can be secured at the opening 20, preventing damage to the cutting blade 2.

[0027] In the valve box cutting machine of the present invention, a shear force is applied to the valve box B from the bottom 15 of the valve box opposite the boss portion 13, and the valve box B is press-cut and cut in half, so that the valve box B can be cut easily in a short time without generating chips.

[0028] Valve box B has an inner diameter of 50 mm or less and was used in a nuclear power plant, and is to be cut as a preliminary process to remove contaminants adhering to the inside of the valve box. Because nuclear power plants have many small-diameter valve boxes with an inner diameter of 50 mm or less, and many of these contain contaminants, the valve box cutting machine of the present invention, which can automatically cut valve boxes used in nuclear power plants, is particularly suitable for use.

[0029] Figure 5 shows a cutting blade 21 constituting a valve box cutter of the second embodiment. This cutting blade 21 has a thick portion 22 in its widthwise center (approximately the center in the left-right direction in Figure 5(b)) that extends along the movement direction (up-down direction) of the cutting blade 21. As shown in Figure 5(a), this thick portion 21 is provided on both the front and back sides of the cutting blade 21. By providing this thick portion 22, it is possible to reduce the contact resistance between the valve box B and the cutting blade 21, and it is possible to cut the valve box B more reliably.

[0030] 6 shows a cutting blade 31 constituting a valve box cutter according to a third embodiment. The tip of this cutting blade 31 is M-shaped when viewed from the front, and the apex 33 of a convex portion 32 forming the center of the M shape and projecting toward the mounting base is located above the tips 34a, 34b at both widthwise ends of the cutting blade 31. With this configuration, the tips 34a, 34b can press the respective joint portions 11, 12 while the convex portion 32 cuts the valve box B from the valve box bottom 15, allowing for stable cutting without shifting the valve box B during cutting.

[0031] Although the present invention has been described above in terms of an embodiment, it is not limited to the above embodiment and various modifications are possible. For example, the valve body of various types of valves, such as a ball valve, a globe valve, and a gate valve, can be cut. In the embodiment, the drive unit 10 is a hydraulic cylinder, but it can be configured with various mechanisms, such as a ball screw mechanism or a linear motor mechanism, as long as it is a mechanism capable of reciprocating. [Explanation of symbols]

[0032] 1. Mounting table 2, 21, 31 cutting blade 3 Pressing means 4 side wall 11, 12 Joint 13 Boss section 16 Tapered section 16a First tapered section 16b Second tapered section 22 Thick part 32 Convex part 33 Vertex 34a, 34b Tip B Valve box

Claims

1. A valve body cutting machine for cutting a valve body, which is a component of a valve and has a pair of joints and a boss portion provided between the joints, and has a liquid flow path formed therein, The cutting device comprises a mounting base on which the valve box is placed, contacting the boss portion of the valve box to be cut; a cutting blade that waits at a position above the mounting base; a pressing means that presses the cutting blade toward the mounting base; and side walls that are provided around the mounting base, sandwiching a pair of joint portions of the valve box placed on the mounting base and guiding the cutting blade downward. A valve box cutting machine characterized in that the cutting blade falls along the side wall while being pressed toward the mounting base, thereby applying a shear force to the valve box placed on the mounting base and press-cutting the valve box.

2. The tip side of the cutting blade has a V-shape that narrows toward the mounting table side when viewed from the front.

2. The valve body cutting machine according to claim 1, wherein the valve body cutting machine is a cutter.

3. 3. The valve body cutter according to claim 2, wherein a thick portion extending along the moving direction of the cutting blade is provided at a central portion in the width direction of the cutting blade.

4. 2. The valve body cutting machine according to claim 1, wherein the tip side of the cutting blade is M-shaped when viewed from the front, and the apex of the convex portion that forms the center of the M-shape and protrudes toward the mounting table is located above the tips of both widthwise end edges of the cutting blade.

5. 2. The valve body cutter according to claim 1, wherein the cutting blade has a tapered portion formed at its tip end that narrows toward both ends in the thickness direction, the tapered portion being composed of a first tapered portion and a second tapered portion that forms the tip end of the cutting blade below the first tapered portion, and the inclination angle of the second tapered portion is larger than the inclination angle of the first tapered portion.

6. 2. The tube cutting machine according to claim 1, wherein the side wall is open around the table in a direction facing the cutting blade.

7. 2. The valve body cutting machine according to claim 1, wherein the valve body has an inner diameter of 50 mm or less and is used in a nuclear power plant, and is cut as a preliminary process for removing contaminants adhering to the inside of the valve body.

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