Welded construction

Abstract

To provide a weld structure which can improve weld durability while preventing a weld crack when a valve body in a valve device is welded with a diaphragm.SOLUTION: A diaphragm valve 10 is provided with: a valve body 13 which is provided in a valve chamber 11; and a metal diaphragm 15 which seals the valve chamber 11, in which the valve body 13 has a shank 13e, and the metal diaphragm 15 is constituted of a thin plate material and constituted by comprising an insertion hole 15a for inserting the shank 13e. The shank 13e is provided with an annular connection part 16 which projects in a radially outside direction and is continuous in a circumferential direction, the insertion hole 15a of the metal diaphragm 15 is provided with a welded part 15b along a first surface 16a of the connection part 16, and tip parts of the connection part 16 and the welded part 15b are welded with each other by a meld-solidification part 17 with a circular cross section.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a welding structure for welding and joining a valve disc and a diaphragm in a valve device including a valve disc provided in a valve chamber and a diaphragm that seals the valve chamber. [Background technology]

[0002] Conventionally, for example, in valve devices used in refrigeration and air conditioning devices, a metal diaphragm is used as a sealing member for sealing a valve chamber (see Patent Document 1, for example). The valve device (diaphragm valve) described in Patent Document 1 includes a valve body (body and bonnet) having a valve chamber and a valve port (valve seat), a valve element (stem and disk) provided so as to be movable forward and backward within the valve chamber, and a metal diaphragm provided across the valve body and the valve element to seal the valve chamber. The metal diaphragm is formed of a thin plate material having a disk shape (dish shape) as a whole, and has an insertion hole (mounting hole) formed in the center through which the shaft of the valve element is inserted. The outer peripheral edge of the metal diaphragm is clamped and fixed to the valve body, and the inner peripheral edge is welded and fixed to the shaft of the valve element.

[0003] In a valve device that controls the flow rate of a high-temperature, high-pressure fluid such as a refrigerant, a stainless steel alloy or a nickel-based alloy that has excellent heat resistance and corrosion resistance is used as the metal material of the metal diaphragm, and a stainless steel alloy is sometimes used as the metal material of the valve body that is the object to be welded. In particular, an austenitic stainless steel (e.g., SUS316L, etc.) is used as the stainless steel alloy, and Inconel (registered trademark, e.g., Inconel 625, etc.), which has excellent heat resistance, corrosion resistance, oxidation resistance, etc., is sometimes used as the nickel-based alloy, and different metal materials are appropriately selected for each part based on factors such as workability and material cost, and these different metal materials are sometimes welded together. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-219303 Summary of the Invention [Problem to be solved by the invention]

[0005] However, austenitic stainless steel is generally known to be a metal material susceptible to weld cracks, and it is expected that welding defects are likely to occur even when dissimilar metal materials, such as austenitic stainless steel and nickel-based alloys, are welded together. In particular, when a metal diaphragm made of a thin plate is welded to a thick valve body, if a weld is formed that penetrates the metal diaphragm in the plate thickness direction and reaches the inside of the valve body, the contraction of the molten metal when solidifying is restricted, so that tensile stress acts on the welded solidified part, making it more likely to cause cracks. For this reason, there has been a demand for a weld structure that can prevent weld cracks in the weld between dissimilar metal materials, such as a metal diaphragm and a valve body, while improving the weld durability.

[0006] An object of the present invention is to provide a welded structure capable of improving weld durability while preventing weld cracks when welding a valve body and a diaphragm in a valve device. [Means for solving the problem]

[0007] The welded structure of the present invention is a welded structure for welding and joining a valve disc and a diaphragm in a valve device including the valve disc provided in a valve chamber and a diaphragm that seals the valve chamber, the valve disc having a cylindrical shaft portion, the diaphragm being made of one or more thin plate materials and having an insertion hole through which the shaft portion is inserted, the shaft portion having a first surface and a protruding annular connecting portion that is continuous in the circumferential direction, the diaphragm being provided with a bent portion bent from an end portion that constitutes the insertion hole and a welded portion continuous with the bent portion, the welded portion having a flat surface that faces the first surface and extends along the first surface, and is annular in the circumferential direction, the connecting portion and the welded portion being A tip end of the connection portion in a protruding direction and a tip end of the welded portionThe welded joint is formed by a continuous annular molten solidified part in the circumferential direction. The molten solidified portion is formed from a second surface opposite to the first surface of the connection portion to another plane opposite to the plane of the welded portion, so that the molten solidified portion is formed throughout the thickness direction of the connection portion and the thickness direction of the welded portion. It is characterized by:

[0008] In this case, a second surface is provided on the opposite side of the first surface in the connection portion, and the first surface and the second surface are provided at an intersection angle that narrows toward the tip of the connection portion.

[0009] The welded structure may be a welded structure for welding together a valve disc and a diaphragm in a valve device including the valve disc provided in a valve chamber and a diaphragm that seals the valve chamber, the valve disc having a cylindrical shaft portion, the diaphragm being composed of one or more thin plate materials and having an insertion hole through which the shaft portion is inserted, the shaft portion having a first surface and a second surface opposite thereto, protruding in the axial direction, and provided with a circumferentially continuous annular connecting portion, the insertion hole of the diaphragm being provided with a circumferentially continuous annular welded portion extending in the axial direction along the first surface of the connecting portion, and the connecting portion and the welded portion having their tips welded together and joined by a molten solidified portion having a circular cross section.

[0010] According to this configuration, the melted and solidified portion having a circular cross section is formed at the tip of the welded portion provided in the connection portion provided on the shaft portion of the valve body and the insertion hole of the diaphragm, so that weld cracks can be prevented. That is, by welding the tip of the connection portion and the tip of the welded portion together, the molten metal becomes circular (spherical if the welded portion is a point) due to surface tension, and even if it shrinks during solidification, the contraction force is less likely to act on the base material, so that the generation of tensile stress due to shrinkage can be suppressed. Therefore, weld cracks can be prevented in the melted and solidified portion and the surrounding base material, and the welding durability can be improved by suppressing residual stress. In addition, the melted and solidified portion is formed in a continuous ring shape in the circumferential direction, and the welding durability of this melted and solidified portion is improved, so that good sealing performance by the diaphragm is maintained, and the product life of the valve device can be extended.

[0011] In this case, it is preferable that the diameter of the molten and solidified portion is equal to or larger than the combined thickness of the tip side of the connection portion and the welded portion.

[0012] According to this configuration, the molten and solidified portion is formed into a circular cross-section with a diameter greater than or equal to the combined thickness dimension of the tip side of the connection portion and the welded portion, thereby enabling the molten and solidified portion to be smoothly continuous with the welded portion and the connection portion, and preventing any edges from remaining at the tips of the welded portion or the connection portion.

[0013] Furthermore, it is preferable that the thickness dimensions of the tip end side of the connecting portion and the tip end side of the welded portion are approximately the same.

[0014] According to this configuration, by welding the tips of the connecting part and the welded part, which have approximately the same thickness dimensions, the amount of molten metal during welding can be made equal and the generated heat and stress can be equalized, thereby suppressing the effects of heat and stress on the base material and preventing weld cracks.

[0015] The stem portion of the valve body may be made mainly of austenitic stainless steel, and the thin plate material of the diaphragm may be made mainly of a nickel-based alloy.

[0016] With this configuration, the stem of the valve body and the thin plate material of the diaphragm are made of dissimilar metal materials, that is, austenitic stainless steel and nickel-base alloy, and weld cracks can be prevented even under conditions that would make weld cracks likely to occur in the melted and solidified portion and the surrounding base material.

[0017] It is also preferable that the diameter of the molten and solidified portion is 1.1 to 1.6 times the combined thickness of the tip side of the connection portion and the welded portion.

[0018] According to this configuration, the diameter of the molten and solidified portion is set to be 1.1 to 1.6 times the combined thickness dimension of the tip side of the connection portion and the welded portion, so that no edges remain at the tips of the welded portion or the connection portion, thereby improving the welding durability and mechanical properties of the welded portion.

[0019] Furthermore, it is preferable that the first surface and the second surface of the connection portion have an intersection angle that narrows toward the tip of the connection portion, and that the intersection angle is 40° or less.

[0020] According to this configuration, the first and second surfaces of the connection portion are arranged at an intersection angle of 40° or less that narrows toward the tip, thereby suppressing the effect on the base material of the contraction force caused when the molten metal solidifies, and preventing weld cracks at the connection portion.

[0021] It is also preferable that the welded portion is formed by a folded portion formed by folding back and overlapping an end of a thin plate material constituting the diaphragm, and that the end edge side of the thin plate material is arranged along the first surface of the connection portion.

[0022] According to this configuration, the welded portion of the diaphragm is formed by folding back and overlapping the end of the thin plate material, thereby increasing the thickness dimension of the welded portion, suppressing the effects of heat during welding and the effects of contraction force during solidification, and preventing weld cracks in the welded portion. Effect of the Invention

[0023] According to the welded structure of the present invention, weld cracks in the welded portion between the diaphragm and the valve body can be prevented while improving the weld durability, thereby extending the product life of the valve device. [Brief description of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view showing a valve device using a welded structure according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view showing a main portion of the valve device. [Diagram 3] FIG. 4 is an enlarged cross-sectional view showing a welding structure in the valve device. [Figure 4] 5 is an enlarged cross-sectional view showing a modified example of the welding structure in the valve device. FIG. [Diagram 5]FIG. 6 is a cross-sectional view showing a valve device using a welded structure according to a second embodiment of the present invention. [Figure 6] FIG. 2 is an enlarged cross-sectional view showing a main portion of the valve device. [Figure 7] FIG. 4 is an enlarged cross-sectional view showing a welding structure in the valve device. [Figure 8] FIG. 4 is an enlarged cross-sectional view showing a welded structure according to a first modified example of the present invention. [Figure 9] FIG. 4 is an enlarged cross-sectional view showing a welded structure according to a second modified example of the present invention. [Figure 10] FIG. 11 is an enlarged cross-sectional view showing a welded structure according to a third modified example of the present invention. [Figure 11] FIG. 11 is an enlarged cross-sectional view showing a welded structure according to a fourth modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] A valve device using a welded structure according to a first embodiment of the present invention will be described with reference to Figs. 1 to 4. The valve device according to this embodiment is provided with a metal diaphragm, which is a displaceable sealing member. Fig. 1 is a cross-sectional view showing a diaphragm valve 10, which is a valve device according to the embodiment. Fig. 2 is an enlarged cross-sectional view showing a main part of the diaphragm valve 10, and is an enlarged view of a part indicated by a circled part A in Fig. 1. Fig. 3 is an enlarged cross-sectional view showing a welded structure in the diaphragm valve 10, and is an enlarged view of a part indicated by a circled part B in Fig. 2. Fig. 3(A) shows a main part of the valve body and the diaphragm which are welded together, and Fig. 3(B) shows the state of the valve body and the diaphragm before they are welded together.

[0026] 1, the diaphragm valve 10 is a manually opened / closed valve comprising a valve body 12 having a valve chamber 11 therein, a valve element 13 provided within the valve chamber 11, an operating part 14 which is rotated to move the valve element 13 back and forth, and a metal diaphragm 15 which seals the inside of the valve chamber 11. The valve body 12 comprises a first member 12a and a second member 12b which are screwed together, and the outer periphery of the metal diaphragm 15 is clamped between the face-to-face portion of the first member 12a and the second member 12b.

[0027] The first member 12a of the valve body 12 is provided with an inlet port 12c that opens at one end and communicates with the valve chamber 11, an outlet port 12d that opens at the other end and communicates with the valve chamber 11, and a valve port 12e that is an opening of the inlet port 12c into the valve chamber 11. The second member 12b of the valve body 12 is formed in an overall cylindrical shape and is provided with a bearing portion 12f that rotatably supports the shaft portion 14b of the operating part 14, and a female thread portion 12g that screws into the male thread portion 14c of the shaft portion 14b.

[0028] As shown in Fig. 2, the valve body 13 is configured to include a cylindrical valve body case 13a having flanges on the top and bottom, a valve member 13b held inside the valve body case 13a, a connecting member 13c held in the valve body case 13a above the valve member 13b, and a ball 13d provided in a recessed hole on the upper surface of the connecting member 13c. The valve member 13b is a resin or rubber packing and is configured to be able to seat on the valve port 12e and seal it. The connecting member 13c has a cylindrical shaft portion 13e extending above the valve body case 13a, and a metal diaphragm 15 is fixed to this shaft portion 13e. The ball 13d is supported in a recessed hole of the connecting member 13c so as to be able to roll freely, and is sandwiched between the connecting member 13c and the abutment portion 14d of the operating portion 14 that abuts against it from above. This sphere 13d absorbs the rotation of the operating part 14 about the central axis X and the tilt of the valve body 13, so that only the downward pressing force from the operating part 14 is transmitted to the valve body 13 via the sphere 13d.

[0029] The operating unit 14 includes a handle 14a, a shaft portion 14b whose upper end is fixed to the handle 14a and extends in the axial direction, a male threaded portion 14c provided on the shaft portion 14b, and a contact portion 14d provided on the tip portion below the male threaded portion 14c. The shaft portion 14b is rotatably supported by a bearing portion 12f of the valve body 12, and the male threaded portion 14c is screwed into the female threaded portion 12g. The contact portion 14d is provided in contact with a sphere 13d of the valve element 13.

[0030] The metal diaphragm 15 is made of a single circular (dish-shaped) thin metal plate, and has an insertion hole 15a formed in the center for inserting the shaft portion 13e of the valve body 13. The outer peripheral edge of the metal diaphragm 15 is sandwiched between the first member 12a and the second member 12b of the valve body 12, and the inner peripheral edge of the insertion hole 15a is welded and fixed to the shaft portion 13e of the valve body 13. The metal diaphragm 15 supports the valve body 13 so as to bend in the out-of-plane direction due to its own elasticity, and supports the valve body 13 so as to be freely movable up and down, and as shown in Figures 1 and 2, the upward biasing force due to the elasticity of the metal diaphragm 15 acts on the valve body 13, supporting the valve body 13 in a valve open position where the valve member 13b is separated from the valve port 12e.

[0031] In such a diaphragm valve 10, by rotating the handle 14a of the operating part 14, the male screw part 13b is guided by the female screw part 12g to move the operating part 14 up and down, and this up and down movement is transmitted to the valve body 13 via the abutment part 14d and the sphere 13d. When the operating part 14 is moved downward by closing the handle 14a, the metal diaphragm 15 is deflected downward out of the plane by the pressing force, and the valve body 13 moves downward, and the valve member 13b is seated on the valve port 12e. When the operating part 14 is moved upward by opening the handle 14a, the valve member 13b moves upward due to the elastic force (restoring force) of the metal diaphragm 15 that tries to return to its initial position, and the valve member 13b is released from the valve port 12e. In this way, the valve member 13b moves forward and backward in the up and down direction between the valve closed position and the valve closed position in accordance with the operation of the handle 14a of the operating part 14.

[0032] Next, the welded structure between the metal diaphragm 15 and the shaft portion 13e of the valve body 13 will be described with reference to Fig. 3. The thickness dimension t of the metal diaphragm 15 is about 0.2 mm to 0.4 mm, and the end portion on the insertion hole 15a side is bent downward and extends radially outward, and is provided with a circumferentially continuous annular welded portion 15b. The thickness dimension T B is approximately equal to the thickness t of the metal diaphragm 15 (T B =t) is about 0.2mm to 0.4mm.

[0033] The shaft portion 13e has a connecting portion 16 formed in a circumferentially continuous ring shape protruding radially outward. As shown in FIG. 3(B), the connecting portion 16 is formed in a protruding shape having a first surface 16a on the upper side along which the welded portion 15b is aligned, a second surface 16b on the opposite side (lower side), and a third surface 16c constituting the tip side of the connecting portion 16, the second surface 16b extending along a plane substantially perpendicular to the central axis X, and the intersection angle θ between the second surface 16b and the first surface 16a is approximately 30°. The thickness dimension T of the tip side of the connecting portion 16 is F and the thickness dimension T of the welded portion 15b. B are equivalent to each other (T F =T B The thickness dimension T of the welded portion 15b is about 0.2 mm to 0.4 mm. B and the thickness dimension T of the tip of the connection part 16 F That is, 0.8≦(T B / T F )≦1.2. In addition, the intersection angle θ between the first surface 16a and the second surface 16b is preferably 40° or less.

[0034] The melted and solidified portion 17 is formed by melting and solidifying the tip portions of the welded portion 15b and the connecting portion 16 by electron beam welding from the tip sides of the welded portion 15b and the connecting portion 16, and is formed in a ring shape that is continuous in the circumferential direction. The melted and solidified portion 17 is formed into a circular cross section by contracting due to the surface tension of the metal molten during welding as it solidifies. The center O of the melted and solidified portion 17 is located on an extension of the contact surface (first surface 16a) between the welded portion 15b and the connecting portion 16, and the radius R of the melted and solidified portion 17 is determined by the thickness dimension T of the welded portion 15b. B and the thickness dimension T of the tip side of the connection part 16 F That is, the diameter of the molten solidified portion 17 is formed to be equal to or larger than the combined thickness of the tip sides of the welded portion 15b and the connection portion 16. It is preferable that the molten solidified portion 17 smoothly continues without leaving any edges at the tips of the welded portion 15b and the connection portion 16, and therefore the diameter of the molten solidified portion 17 is preferably 1.1 to 1.6 times the combined thickness of the tip sides of the welded portion 15b and the connection portion 16.

[0035] Next, the metal material of each member constituting the diaphragm valve 10 will be described. The metal diaphragm 15 is mainly composed of a nickel-based alloy. Inconel (registered trademark), which has excellent heat resistance, corrosion resistance, and oxidation resistance, is suitable as the nickel-based alloy. The nickel-based alloy contains 50% or more of nickel, and examples thereof include NCF600, NCF601, NCF625, NCF690, NCF718, NCF750, NCF751, and NCF80A (the above symbols are based on JIS G 4902:1992 corrosion-resistant and heat-resistant superalloy plate).

[0036] The connecting member 13c of the valve body 13 is mainly made of austenitic stainless steel. As the austenitic stainless steel, SUS304 series is suitable, and among them, SUS316L, SUS316LN, SUS321, and SUS347, which have excellent corrosion resistance, can be exemplified. The molten and solidified portion 17 formed by welding the connecting member 13c made of such austenitic stainless steel and the metal diaphragm 15 made of a nickel-based alloy is mainly in the austenite phase.

[0037] The welded structure in this embodiment may be as shown in the following Fig. 4. Fig. 4 is an enlarged cross-sectional view showing a modified example of the welded structure in the diaphragm valve 10.

[0038] In the modified welded structure shown in Fig. 4, the metal diaphragm 15 is made of a thin plate material with a thickness dimension t of about 0.1 mm to 0.2 mm, and the welded portion 15b is configured by folding back an end of the thin plate material. The welded portion 15b is formed in a continuous ring shape in the circumferential direction, and the edge side of the thin plate material is provided along the first surface 16a of the connection portion 16. The thickness dimension T B is the dimension of two laminated thin plates (T B = 2t) and is about 0.2 mm to 0.4 mm. A first surface 16a of the connecting portion 16 extends along a plane inclined at approximately 45° with respect to the central axis X, and an intersection angle θ between this first surface 16a and a second surface 16b is about 10°.

[0039] According to the above embodiment, the melted and solidified portion 17 is provided at the tip of the welded portion 15b of the metal diaphragm 15 and the connecting portion 16 of the valve body 13, and the melted and solidified portion 17 is formed in a circular cross section having a diameter equal to or greater than the combined thickness of the welded portion 15b and the connecting portion 16. By welding the tips of the welded portion 15b and the connecting portion 16 together in this manner, the molten metal has a circular cross section due to surface tension, and even if it shrinks during solidification, the contraction force is less likely to act on the base material, and the generation of tensile stress due to shrinkage can be suppressed. Therefore, it is possible to prevent weld cracks in the melted and solidified portion 17 and the surrounding base material, and the welding durability can be improved by suppressing residual stress.

[0040] The thickness dimension T of the tip side of the welded portion 15b of the metal diaphragm 15 and the tip side of the connection portion 16 of the valve body 13 F ,T B By welding together the tips of the welded part 15b and the connecting part 16, which have similar thickness dimensions, the amount of molten metal during welding can be made equal, and the generated heat and stress can be equalized, thereby suppressing the effects of heat and stress on the base material and preventing weld cracks.

[0041] Furthermore, since the connecting member 13c of the valve body 13 is made mainly of austenitic stainless steel, the metal diaphragm 15 is made mainly of a nickel-based alloy, and the molten solidified portion 17 is made of dissimilar metal materials that are mainly in the austenitic phase, weld cracks can be prevented even under conditions that would make weld cracks likely to occur in the molten solidified portion 17 and the surrounding base material.

[0042] In addition, by forming the diameter of the molten solidified portion 17 to be greater than or equal to the combined thickness dimension of the tip sides of the welded portion 15b and the connection portion 16, the molten solidified portion 17 is smoothly continuous with the welded portion 15b and the connection portion 16, and no edges remain at the tips of the welded portion 15b or the connection portion 16, thereby improving the welding durability and mechanical properties of the weld.

[0043] In addition, the first surface 16a and the second surface 16b of the connection portion 16 are arranged at an intersection angle θ of 40° or less, which narrows toward the tip, thereby suppressing the effect on the base material of the contraction force caused when the molten metal solidifies, and preventing weld cracks around the connection portion 16.

[0044] Furthermore, in metal diaphragm 15, as shown in FIG. 4, by forming welded portion 15b by folding back and overlapping the ends of a thin plate material, the thickness dimension of welded portion 15b is increased, which suppresses the effects of heat during welding and the effects of contraction force during solidification and prevents weld cracks in welded portion 15b.

[0045] In addition, in the metal diaphragm 15 of the diaphragm valve 10, a circumferentially continuous molten and solidified portion 17 is formed, and weld cracks around this molten and solidified portion 17 are prevented and welding durability is improved, thereby maintaining good sealing properties of the metal diaphragm 15 and extending the product life of the diaphragm valve 10.

[0046] Next, a valve device using a welded structure according to a second embodiment of the present invention will be described with reference to Figs. 5 to 7. Fig. 5 is a cross-sectional view showing a diaphragm valve 20 which is the valve device of this embodiment. Fig. 6 is an enlarged cross-sectional view showing a main part of the diaphragm valve 20, and is an enlarged view of a part indicated by a circled part A in Fig. 5. Fig. 7 is an enlarged cross-sectional view showing a welded structure in the diaphragm valve 20, and is an enlarged view of a part indicated by a circled part B in Fig. 6. Fig. 7(A) shows the main parts of the valve body and diaphragm which have been welded together, and Fig. 7(B) shows the state of the valve body and diaphragm before they are welded together.

[0047] The diaphragm valve 20 is a manually opened / closed type valve having a structure substantially similar to that of the diaphragm valve 10 of the first embodiment, and as shown in Fig. 5, comprises a valve body 22 having a valve chamber 21 therein, a valve element 23 provided in the valve chamber 21, an operating part 24 which is rotated to move the valve element 23 back and forth, and a metal diaphragm 25 which seals the inside of the valve chamber 21. The valve body 22 comprises a first member 22a and a second member 22b which are screwed together, and the outer periphery of the metal diaphragm 25 is clamped by the face-to-face portion of the first member 22a and the second member 22b.

[0048] The first member 22a of the valve body 22 includes an inlet port 22c, an outlet port 22d, and a valve port 22e, and the second member 22b includes a bearing portion 22f and a female thread portion 22g. As shown in Fig. 6, the valve body 23 includes a valve body case 23a, a valve member 23b, a connecting member 23c, and a ball 23d. The connecting member 23c includes a cylindrical shaft portion 23e, and a metal diaphragm 25 is fixed to the shaft portion 23e. The operating portion 24 includes a handle 24a, a shaft portion 24b, a male thread portion 24c, and a contact portion 24d.

[0049] The metal diaphragm 25 is made of a single circular (dish-shaped) thin metal plate, and has an insertion hole 25a formed in the center for inserting the shaft portion 23e of the valve body 23. The metal diaphragm 25 has an outer circumferential edge sandwiched between the first member 22a and the second member 22b of the valve body 22, and an inner circumferential edge of the insertion hole 25a is fixed to the shaft portion 23e of the valve body 23 by welding.

[0050] Next, the welded structure between the metal diaphragm 25 and the shaft portion 23e of the valve body 23 will be described with reference to Fig. 7. The thickness dimension t of the metal diaphragm 25 is about 0.2 mm to 0.4 mm, and the end portion on the side of the insertion hole 25a is bent upward along the axial direction (the direction of the central axis X) and is provided with a ring-shaped welded portion 25b that is continuous in the circumferential direction. The thickness dimension T B is approximately equal to the thickness t of the metal diaphragm 25 (T B =t) is about 0.2mm to 0.4mm.

[0051] The shaft portion 23e has a connecting portion 26 that protrudes upward along the axial direction and is formed in a circumferentially continuous ring shape. As shown in Fig. 7(B), the connecting portion 26 is formed in a protruding shape having a first surface 26a on the radially outer side along which the welded portion 25b is aligned, a second surface 26b on the opposite side (radially inner side), and a third surface 26c that constitutes the tip side of the connecting portion 26, and the intersection angle θ between the first surface 26a and the second surface 26b is about 20°. The thickness dimension T of the tip side of the connecting portion 26 is F and the thickness dimension T of the welded portion 25b. B are equivalent to each other (T F =T B The thickness dimension T of the welded portion 25b is about 0.2 mm to 0.4 mm. B and the thickness dimension T of the tip side of the connection part 26 F That is, 0.8≦(T B / T F )≦1.2. In addition, the intersection angle θ between the first surface 26a and the second surface 26b is preferably 40° or less.

[0052] The melted and solidified portion 27 is formed by melting and solidifying the tip portions of the welded portion 25b and the connecting portion 26 by electron beam welding from the tip sides of the welded portion 25b and the connecting portion 26, and is formed in a ring shape that is continuous in the circumferential direction. The melted and solidified portion 27 is formed into a circular cross section by contracting due to the surface tension of the metal molten during welding as it solidifies. The center O of the melted and solidified portion 27 is located on an extension line of the contact surface (first surface 26a) between the welded portion 25b and the connecting portion 26, and the radius R of the melted and solidified portion 27 is determined by the thickness dimension T of the welded portion 25b. B and the thickness dimension T of the tip side of the connection part 26 F That is, the diameter of the molten solidified portion 27 is formed to be equal to or larger than the combined thickness of the tip sides of the welded portion 25b and the connection portion 26. It is preferable that the molten solidified portion 27 smoothly continues without leaving any edges at the tips of the welded portion 25b and the connection portion 26, and therefore the diameter of the molten solidified portion 27 is preferably 1.1 to 1.6 times the combined thickness of the tip sides of the welded portion 25b and the connection portion 26.

[0053] The metal material of each member constituting the diaphragm valve 20 is the same as that of the diaphragm valve 10 of the first embodiment, the metal diaphragm 25 is mainly made of a nickel-based alloy, and the connecting member 23c of the valve body 23 is mainly made of austenitic stainless steel. Therefore, the molten solidified portion 27 formed by welding the connecting member 23c and the metal diaphragm 25 is mainly in the austenitic phase. In this embodiment, the welded portion 25b may be bent axially downward from the end of the metal diaphragm 25 on the insertion hole 25a side, and the connecting portion 26 may be provided so as to protrude axially downward from the shaft portion 23e, and the tip portions of the welded portion 25b and the connecting portion 26 may be welded together.

[0054] According to the present embodiment, the same effects as those of the first embodiment can be obtained, and weld cracks in the molten solidified portion 27 and the surrounding base material can be prevented, and the welding durability can be improved by suppressing residual stress. Therefore, the excellent sealing performance of the metal diaphragm 25 can be maintained, and the product life of the diaphragm valve 20 can be extended.

[0055] The present invention is not limited to the above-described embodiment, but includes other configurations that can achieve the object of the present invention, and the following modifications are also included in the present invention. For example, in the above-described embodiment, a manually opened / closed valve is exemplified as the valve device, but the valve device of the present invention can also be applied to an electrically operated valve driven by a motor, or to valves having other opening / closing modes.

[0056] In the above embodiment, the combination of austenitic stainless steel and nickel-based alloy is exemplified as the metal material of the shaft portion 13e, 23e of the valve body 13, 23 and the metal diaphragm 15, 25, but the metal materials of each portion may be the same type or different metals other than those in the above embodiment. The shapes and dimensions of the welded portions 15b, 25b of the metal diaphragms 15, 25 and the connection portions 16, 26 of the valve body 13, 23 are not limited to those in the above embodiment, and it is sufficient that the molten and solidified portions formed at their tips have a circular cross section.

[0057] In addition, in the above embodiment, the tip portions of the welded portions 15b, 25b and the connecting portions 16, 26 are welded by electron beam welding to form the molten and solidified portion 17, but this is not limited to the above, and any appropriate welding method such as laser welding or microplasma welding (TIG welding) can be used.

[0058] In addition, in the second embodiment, the end of the metal diaphragm 25 on the insertion hole 25a side is provided with a welded portion 25b bent upward along the axial direction, but the diaphragm may be bent along the axial direction on the insertion hole side and then bent along the radial direction.

[0059] For example, as a first modified example, as shown in FIG. 8, the metal diaphragm 3 may have a first annular portion 31 extending in the axial direction along the first surface 26a of the connecting portion 26, and a second annular portion 32 extending in the radially inward direction from the tip of the first annular portion 31. The first annular portion 31 corresponds to the welded portion 25b of the second embodiment, and is formed continuously in the circumferential direction. The second annular portion 32 is formed continuously in the circumferential direction and is overlapped on the third surface 26c, which is the tip of the connecting portion 26. The second annular portion 32 and the tip of the connecting portion 26 are melted and solidified by electron beam welding to form a circumferentially continuous ring-shaped melted and solidified portion 33. At this time, the tip of the first annular portion 31 may also be melted and solidified at the same time. In the illustrated shape, the entire second annular portion 32 is melted, but only the tip of the second annular portion 32 may be melted.

[0060] In the first modified example, the connection portion 26 protrudes along the axial direction as in the second embodiment. However, in a configuration in which the connection portion 16 protrudes along the radial direction as in the first embodiment, the diaphragm may be provided with a first annular portion that extends radially outward along the first surface 16a of the connection portion 16 and is continuous in the circumferential direction, and a second annular portion that extends axially from the tip of the first annular portion, is overlapped with the tip portion of the connection portion 16, and is continuous in the circumferential direction.

[0061] In the above embodiment, the metal diaphragms 15 and 25 are made of one thin metal plate, but the diaphragms may be made of multiple thin plates. For example, the metal diaphragms may be made of two thin metal plates, as in the welded structures shown in Figs. 9 to 11 as second to fourth modified examples.

[0062] In the welded structure of the second modification, the metal diaphragm 4 has a first thin plate 41 on the upper side and a second thin plate 42 on the lower side. The first thin plate 41 has a first annular portion 411 extending in the axial direction along the first surface 26a of the connecting portion 26, and a second annular portion 412 extending in the radially inward direction from the tip of the first annular portion 411, and has a shape similar to that of the metal diaphragm 3 in the first modification. The second thin plate 42 has a welded portion 421 extending in the axial direction along the first surface 26a of the connecting portion 26, and has a shape similar to that of the metal diaphragm 25 in the second embodiment. The tip of the second annular portion 412, the tip of the welded portion 421, and the tip of the connecting portion 26 are melted and solidified by electron beam welding to form a ring-shaped melted and solidified portion 43 that is continuous in the circumferential direction. At this time, the tip of the first annular portion 411 may also be melted and solidified at the same time.

[0063] In the welded structure of the third modified example, the metal diaphragm 5 has an upper first thin plate 51 and a lower second thin plate 52. The first thin plate 51 has a first annular portion 511 extending in the axial direction along the first surface 26a of the connecting portion 26 and a second annular portion 512 extending in the radially inward direction from the tip of the first annular portion 511, and has a similar shape to the metal diaphragm 3 in the first modified example. The second thin plate 52 has a first annular portion 521 extending in the axial direction along the first surface 26a of the connecting portion 26 and a second annular portion 522 extending in the radially inward direction from the tip of the first annular portion 521, and has a similar shape to the metal diaphragm 3 in the first modified example. By electron beam welding, the tip portion of the second annular portion 512, the tip portion of the second annular portion 522, and the tip portion of the connection portion 26 are melted and solidified to form a circumferentially continuous annular melted and solidified portion 53. At this time, the tip portions of the first annular portions 511 and 521 may also be melted and solidified at the same time.

[0064] In the welded structure of the fourth modification, the metal diaphragm 6 has a first thin plate 61 on the upper side and a second thin plate 62 on the lower side. The first thin plate 61 has a welded portion 611 extending in the axial direction along the first surface 26a of the connection portion 26, and has a shape similar to that of the metal diaphragm 25 of the second embodiment. The second thin plate 62 has a welded portion 621 extending in the axial direction along the first surface 26a of the connection portion 26, and has a shape similar to that of the metal diaphragm 25 of the second embodiment. The tip of the welded portion 611, the tip of the welded portion 621, and the tip of the connection portion 26 are melted and solidified by electron beam welding to form a ring-shaped melted and solidified portion 63 that is continuous in the circumferential direction.

[0065] In the second to fourth modified examples, the total thickness dimension of the first thin plate and the second thin plate may be approximately the same as the thickness direction dimension t of the metal diaphragms 15, 25 in the above embodiment. Also, the melt-solidified portions 33, 43, 53, 63 in the first to fourth modified examples may have approximately the same dimensions as the melt-solidified portions 17, 27 in the above embodiment.

[0066] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention. [Explanation of symbols]

[0067] 10,20 Diaphragm valve (valve device) 11,21 Valve chamber 13,23 Valve body 13e,23e Shaft part 15,25,3~6 Metal diaphragm 15a, 25a Insertion hole 15b, 25b, 421, 611, 621 Part to be welded 16,26 Connection 16a,26a Front page 16b,26b Second side 17, 27, 33, 43, 53, 63 Melted and solidified parts 31, 411, 511, 521 First annular section 32, 412, 512, 522 Second annular section

Claims

1. A welding structure for welding and joining a valve body and a diaphragm in a valve device including a valve body provided in a valve chamber and a diaphragm that seals the valve chamber, comprising: The valve body has a cylindrical shaft portion, The diaphragm is made of one or more thin plate materials and has an insertion hole through which the shaft portion is inserted, The shaft portion is provided with a ring-shaped connecting portion that protrudes and has a first surface and is continuous in a circumferential direction, The diaphragm is provided with a bent portion bent from an end portion constituting the insertion hole, and a welded portion continuous with the bent portion, The welded portion has a flat surface that faces the first surface and extends along the first surface, and is formed into a circumferentially continuous ring shape, The connection portion and the welded portion are joined by a circumferentially continuous annular molten solidified portion in which a tip end of the connection portion in a protruding direction and a tip end of the welded portion are welded to each other, A welded structure characterized in that the molten solidified portion is formed from a second surface opposite the first surface of the connection portion to another plane opposite the plane of the welded portion, thereby being formed throughout the entire thickness direction of the connection portion and the thickness direction of the welded portion.

2. A second surface is provided on the opposite side of the first surface in the connection portion, The welded structure according to claim 1 , wherein the first surface and the second surface are provided at an intersection angle that narrows toward a tip of the connection portion.

3. 3. The welded structure according to claim 1, wherein a thickness dimension of a tip end side of the connecting portion and a thickness dimension of a tip end side of the welded portion are approximately the same.

4. 4. The welded structure according to claim 1, wherein the stem portion of the valve body is made mainly of austenitic stainless steel, and the thin plate material of the diaphragm is made mainly of a nickel-based alloy.

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