Metallic joined structure, impeller, pump, and method for producing metallic joined structure

Abstract

This metallic joined structure (100) comprises: metal plates (110, 130) (first metal plates); a metal plate (120) (second metal plate) that is butted against the metal plates (110, 130) in a T-shape; and joining parts (140) that join the metal plates (110, 130) and the metal plate (120). The joining parts (140) comprise: first joining parts (141) that are disposed on one surface (121) side of the metal plate (120); and second joining parts (142) that are disposed on the other surface (122) side of the metal plate (120) and that are smaller than the first joining parts (141).

Description

Metal bonded body, impeller, pump, and method for manufacturing metal bonded body

[0001] The present invention relates to a joined metal body, an impeller, a pump, and a method for manufacturing the joined metal body. This application claims priority to Japanese Patent Application No. 2023-194436, filed on November 15, 2023, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 below discloses an impeller used in a pump for pumping liquid. This impeller includes a main plate having a through hole into which a rotating shaft of the pump is inserted, a plurality of blades fixed to the main plate, and a side plate having a fluid inlet. The plurality of blades are joined to the main plate and the side plate by projection welding.

[0003] Japanese Patent Application Publication No. 2020-84769

[0004] The T-shaped projection welding used in the manufacture of impellers, guide vanes, etc. has a problem in that the large joint portion protruding from the blade increases fluid resistance.

[0005] The present invention has been made in view of the above problems, and has as its object to provide a metal joined body, an impeller, a pump, and a method for manufacturing the metal joined body, which are capable of reducing fluid resistance.

[0006] (1): A metal joined body according to one embodiment of the present invention comprises a first metal plate, a second metal plate butted against the first metal plate in a T-shape, and a joint that joins the first metal plate and the second metal plate, wherein the joint comprises a first joint that is arranged on one side of the second metal plate, and a second joint that is arranged on the other side of the second metal plate and is smaller than the first joint.

[0007] (2) In the metal bonded body according to (1), the second bonding portion may have a flat portion.

[0008] (3) In the metal joined body according to (2), the flat portion may include a first flat portion extending along the first metal plate and a second flat portion extending along the second metal plate.

[0009] (4) In the metal joined body according to (3), the angle formed between the first flat surface portion and the second flat surface portion may be a right angle.

[0010] (5): An impeller according to one aspect of the present invention includes a metal joint body according to any one of (1) to (4), wherein the first metal plate forms at least one of a main plate and a side plate, the second metal plate forms a plurality of blades joined to the main plate and the side plate, and the second joint portion is arranged on the pressure side of the blade, and the first joint portion is arranged on the suction side of the blade.

[0011] (6) A pump according to one aspect of the present invention includes the impeller described in (5).

[0012] (7): A method for manufacturing a metal joined body according to one aspect of the present invention includes butting a second metal plate against a first metal plate in a T-shape and performing projection welding to form a first joint on one side of the second metal plate and a second joint smaller than the first joint on the other side of the second metal plate.

[0013] (8): In the method for manufacturing a metal joined body according to (7), the projection welding may be performed with a ceramic plate abutting against the other surface of the second metal plate, and then the ceramic plate may be removed.

[0014] According to the above aspect of the present invention, it is possible to provide a metal joined body, an impeller, a pump, and a method for manufacturing a metal joined body that can reduce fluid resistance.

[0015] FIG. 1 is a cross-sectional configuration diagram of a metal bonded body according to an embodiment; FIG. 2 is a diagram showing one step of a method for manufacturing a metal bonded body according to an embodiment; FIG. 3 is a diagram showing one step of a method for manufacturing a metal bonded body according to an embodiment; FIG. 4 is a diagram showing one step of a method for manufacturing a metal bonded body according to a first modified example; FIG. 5 is a diagram showing one step of a method for manufacturing a metal bonded body according to a first modified example; FIG. 6 is a diagram showing one step of a method for manufacturing a metal bonded body according to a second modified example; FIG. 7 is a diagram showing one step of a method for manufacturing a metal bonded body according to the second modified example; FIG. 8 is a plan view of an impeller according to an embodiment; FIG. 9 is a cross-sectional view of an impeller according to an embodiment; FIG. 10 is a cross-sectional configuration diagram of a pump according to an embodiment.

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

[0017] Fig. 1 is a cross-sectional view of a metal bonded body 100 according to one embodiment. As shown in Fig. 1, the metal bonded body 100 includes a metal plate 110, a metal plate 120, and a metal plate 130. The metal plate 120 is joined to the metal plate 110 in a state where it abuts against the metal plate 110 in a T-shape. The metal plate 120 is also joined to the metal plate 130 in a state where it abuts against the metal plate 130 in a T-shape.

[0018] Note that the term "T-shaped" refers not only to a state in which the angle between metal plate 110 and metal plate 120 is a right angle (90°) as shown in FIG. 1 , but also to a state in which the angle is approximately a right angle. "Approximately a right angle" refers to an angle in which an inclination of about 90°±10° is permitted, for example. Similarly, the angle between metal plate 120 and metal plate 130 may be not only a right angle but also an approximately right angle.

[0019] In the following description, an XYZ Cartesian coordinate system is set, and the positional relationship of each component is sometimes described with reference to this XYZ Cartesian coordinate system. In Fig. 1, the X-axis direction is set to the thickness direction of the metal plate 120. The Y-axis direction and the Z-axis direction are set to the directions along the main surface (plate surface) of the metal plate 120.

[0020] The "principal surfaces" refer to a set of surfaces with the largest area among the six sides of the metal plate 120 when the metal plate 120 is considered to be a hexahedron surrounded by six rectangles. The same applies to the metal plates 110 and 130.

[0021] In the following description, one side and the other side in the X-axis direction may be referred to as the -X side and the +X side, one side and the other side in the Y-axis direction may be referred to as the -Y side and the +Y side, and one side and the other side in the Z-axis direction may be referred to as the -Z side and the +Z side. Hereinafter, for convenience of description, the metal plate 110 side (+Z side) with respect to the metal plate 120 will be referred to as the upper side, and the metal plate 130 side (-Z side) with respect to the metal plate 120 will be referred to as the lower side, but the Z-axis direction does not necessarily have to coincide with the direction of gravity.

[0022] The metal plate 110 extends along the XY plane. The metal plate 110 has an upper surface 111 facing the +Z side and a lower surface 112 facing the -Z side. The upper surface 111 and the lower surface 112 are the main surfaces (plate surfaces) of the metal plate 110.

[0023] The metal plate 120 extends along the YZ plane. The metal plate 120 has one surface 121 (left side surface) facing the -X side and the other surface 122 (right side surface) facing the +X side. The one surface 121 and the other surface 122 are the main surfaces (plate surfaces) of the metal plate 120.

[0024] The metal plate 130 extends along the XY plane. The metal plate 130 has an upper surface 131 facing the +Z side and a lower surface 132 facing the -Z side. The upper surface 131 and the lower surface 132 are the main surfaces (plate surfaces) of the metal plate 130.

[0025] An upper end surface 123 of the metal plate 120 is joined to a lower surface 112 of the metal plate 110 by a joint 140. In addition, a lower end surface 124 of the metal plate 120 is joined to the lower surface 112 of the metal plate 110 by a joint 140. These joints 140 are weld metal formed by projection welding, which will be described later.

[0026] The joint portion 140 includes a first joint portion 141 disposed on one surface 121 of the metal plate 120, and a second joint portion 142 disposed on the other surface 122 of the metal plate 120 and smaller than the first joint portion 141. Note that "smaller than the first joint portion 141" means that the cross-sectional area of ​​the second joint portion 142 is smaller than the cross-sectional area of ​​the first joint portion 141 in the cross-sectional view shown in FIG.

[0027] The first joint portion 141 bulges outward in a convex shape at each of the butt joints between the metal plates 110 and 120 and between the butt joints between the metal plates 130 and 120. Specifically, the first joint portion 141 has a quadrant shape (a sector shape that is 1 / 4 of a circle) in the cross-sectional view shown in FIG. 1 . Note that the first joint portion 141 is not limited to a quadrant shape and may have, for example, a 1 / 4 shape of an ellipse or a convex or concave parabolic shape. Furthermore, the first joint portion 141 may have a curved surface or an uneven surface that cannot be defined by a circle, an ellipse, or a parabola.

[0028] The second joint portion 142 is formed with an inwardly concave shape at each of the butt joints between the metal plates 110 and 120 and between the metal plates 130 and 120. Specifically, the second joint portion 142 has an L-shape in the cross-sectional view shown in Fig. 1. The second joint portion 142 shown in Fig. 1 includes a first flat surface portion 142a that fits along the metal plate 110 (or the metal plate 130) and a second flat surface portion 142b that fits along the metal plate 120.

[0029] The first flat surface 142a is formed with a constant thickness along the lower surface 112 of the metal plate 110. The second flat surface 142b is formed with a constant thickness along the other surface 122 of the metal plate 110. The angle between the first flat surface 142a and the second flat surface 142b is a right angle, which is due to the manufacturing method of the metal bonded body 100 described below. When the angle between the metal plates 110 and 120 is a substantially right angle, the angle between the first flat surface 142a and the second flat surface 142b formed at the butt joint between the metal plates 110 and 120 is also a substantially right angle. The connection portion (corner portion) between the first flat surface 142a and the second flat surface 142b may include a curved surface.

[0030] Next, a method for manufacturing the metal bonded body 100 having the above-described configuration will be described.

[0031] 2A and 2B are views showing a step of a manufacturing method of a metal bonded body 100 according to one embodiment. Specifically, Fig. 2A and Fig. 2B show a state in which a metal plate 120 is butted against a metal plate 110 in a T-shape and projection-welded to the metal plate 110. Note that Fig. 2A and Fig. 2B show different viewing directions of the objects (metal plates 110, 120, etc.).

[0032] A protrusion 125 (projection) that protrudes toward the +Z side is formed on an upper end surface 123 of the metal plate 120. The metal plate 120 is fixed to a jig 200. As shown in Fig. 2A, the jig 200 has an accommodation groove 201 that accommodates the metal plate 120. A ceramic plate 300 is accommodated in the accommodation groove 201 together with the metal plate 120.

[0033] The ceramic plate 300 extends along the YZ plane. The ceramic plate 300 has one surface 301 (left side surface) facing the -X side and the other surface 302 (right side surface) facing the +X side. The one surface 301 and the other surface 302 are the main surfaces (plate surfaces) of the ceramic plate 300.

[0034] One surface 301 of ceramic plate 300 abuts against the other surface 122 of metal plate 120. Furthermore, upper end surface 303 of ceramic plate 300 is disposed so as to coincide with upper end surface 123 of metal plate 120. In other words, upper end surface 303 of ceramic plate 300 and upper end surface 123 of metal plate 120 are positioned at the same position in the Z-axis direction. As shown in FIG. 2B , the dimension of ceramic plate 300 in the Y-axis direction (plate width direction) is larger than the dimension of protrusion 125 in the Y-axis direction.

[0035] Projection welding (projection welding between metal plate 110 and metal plate 120) refers to resistance welding (spot welding) between metal plate 110 and metal plate 120 by pressing protrusion 125 of metal plate 120 against metal plate 110 in the state shown in Figures 2A and 2B, passing a large current through protrusion 125 from an electrode (not shown), and melting protrusion 125.

[0036] When the protrusion 125 melts, the lower surface 112 of the metal plate 110 and the upper end surface 123 of the metal plate 120 approach each other in the Z-axis direction. The molten metal of the protrusion 125 extruded from between the lower surface 112 of the metal plate 110 and the upper end surface 123 of the metal plate 120 overflows onto one surface 121 and the other surface 122 of the metal plate 120. However, because the ceramic plate 300 is disposed on the other surface 122 of the metal plate 120, most of the molten metal of the protrusion 125 overflows onto the one surface 121 of the metal plate 120. This forms the first joint 141 (first joint 141 at the butt joint between the metal plates 110 and 120) shown in FIG.

[0037] Furthermore, the remainder of the molten metal from the protrusion 125 overflows onto the other surface 122 of the metal plate 120, and this molten metal enters the gap between the lower surface 112 of the metal plate 110 and the upper end surface 123 of the ceramic plate 300, and the gap between the other surface 122 of the metal plate 120 and one surface 301 of the ceramic plate 300. After the molten metal has solidified, the metal plate 120 and the ceramic plate 300 are removed from the accommodation groove 201, and the ceramic plate 300 is removed. This forms a second joint 142 having a flat portion (second joint 142 at the butt point of the metal plate 110 and the metal plate 120) as shown in FIG.

[0038] In the above example, a method for forming the first joint 141 and the second joint 142 at the butt joint between the metal plates 110 and 120 (projection welding between the metal plates 110 and 120) has been described. Using a similar method, the first joint 141 and the second joint 142 can be formed at the butt joint between the metal plates 130 and 120 (projection welding between the metal plates 130 and 120 can be performed). Note that if a resin plate or a metal plate is used instead of the ceramic plate 300 in projection welding, the resin or metal will be welded to the metal plate 110 or the metal plate 120. However, if the ceramic plate 300 is used in projection welding, the ceramic will not be welded to the metal plate 110 or the metal plate 120, and the ceramic plate 300 can be easily removed.

[0039] As a result of the above, a first joint portion 141 can be formed on one surface 121 of the metal plate 120, and a second joint portion 142 smaller than the first joint portion 141 can be formed on the other surface 122 of the metal plate 120.

[0040] The first bonding portion 141 and the second bonding portion 142, which is smaller than the first bonding portion 141, can also be formed by the following method.

[0041] 3A and 3B are diagrams showing a step of a method for manufacturing a metal joined body 100 according to a first modified example. Note that Fig. 3A and Fig. 3B show electrodes 210, 220 through which a current flows during projection welding. The electrode 210 is disposed on the upper surface 111 side of the metal plate 110. The electrode 220 is disposed on the lower end surface 124 side of the metal plate 120.

[0042] 3A and 3B uses an insulating material 310. As shown in FIG. 3A , the insulating material 310 is disposed between the upper surface 111 of the metal plate 120 and the electrode 210 on the other surface 122 side of the metal plate 120. This configuration allows the current density during projection welding to be biased toward the one surface 121 side of the metal plate 120, thereby forming a large first joint 141 on the one surface 121 side of the metal plate 120 and a small second joint 142 on the other surface 122 side of the metal plate 120. In the above example, a method for forming the first joint 141 and the second joint 142 at the butt joint between the metal plates 110 and 120 (projection welding of the metal plates 110 and 120) has been described. Using a similar method, the first joint portion 141 and the second joint portion 142 can be formed at the butt joint between the metal plates 130 and 120 (projection welding between the metal plates 130 and 120 can be performed).

[0043] 4A and 4B are diagrams showing a step of a method for manufacturing a metal bonded body 100 according to a second modified example. In the method shown in Fig. 4A and 4B, a convex portion 330 is formed on a jig 200 instead of a ceramic plate 300 or an insulating material 310.

[0044] The protrusion 330 is part of the metal jig 200 and is disposed on the other surface 122 of the metal plate 120. That is, the protrusion 330 is disposed on the upper surface of the jig 200 and is located on the +X side of the other surface 122 of the metal plate 120. The protrusion 330 protrudes on the +Z side toward the metal plate 110. With this configuration, the current density during projection welding can be biased toward the one surface 121 of the metal plate 120, thereby forming a large first joint 141 on the one surface 121 of the metal plate 120 and forming a small second joint 142 on the other surface 122 of the metal plate 120. In the above example, a method for forming the first joint 141 and the second joint 142 at the butt joint between the metal plates 110 and 120 (projection welding between the metal plates 110 and 120) has been described. Using a similar method, the first joint portion 141 and the second joint portion 142 can be formed at the butt joint between the metal plates 130 and 120 (projection welding between the metal plates 130 and 120 can be performed).

[0045] Next, application examples of the metal bonded body 100 will be described.

[0046] FIG. 5 is a plan view of the impeller 3 according to one embodiment. FIG. 6 is a cross-sectional view of the impeller 3 according to one embodiment. As shown in these figures, the impeller 3 includes a main plate 3a, a side plate 3b, and a plurality of blades 3c. The main plate 3a is formed in a circular plate shape and has an insertion hole formed in its center for inserting a rotation shaft (not shown). The side plate 3b is formed in an annular shape coaxial with the main plate 3a and is disposed with a gap in the axial direction from the main plate 3a. The main plate 3a and the side plate 3b are connected via a plurality of blades 3c. The space surrounded by the main plate 3a, the side plate 3b, and the plurality of blades 3c forms a flow path that guides fluid radially outward. The side plate 3b forms an inlet port of the impeller 3.

[0047] The impeller 3 includes a metal joined body 100 shown in FIG. 1 . Specifically, the main plate 3a corresponds to the metal plate 130, the side plate 3b corresponds to the metal plate 110, and the blade 3c corresponds to the metal plate 120. As shown in FIG. 6 , a second joining portion 142 is disposed on the pressure surface 3c2 side of the blade 3c, and a first joining portion 141 is disposed on the suction surface 3c1 side of the blade 3c. The "pressure surface 3c2 of the blade 3c" refers to the surface facing forward in the direction of rotation of the impeller 3. The "suction surface 3c1 of the blade 3c" refers to the surface facing backward in the direction of rotation of the impeller 3.

[0048] Fig. 7 is a cross-sectional view of a pump 1 according to one embodiment. The pump 1 shown in Fig. 7 is a vertical multi-stage pump including a rotating shaft 2 extending vertically and a plurality of impellers 3 fixed to the rotating shaft 2. Specifically, the pump 1 includes a pump section 10, a motor section (not shown), and a coupling section 30. The coupling section 30 is disposed above the pump section 10 and connects the rotating shaft 2 of the pump section 10 to the rotating shaft 6 of the motor section via couplings 4 and 5. The couplings 4 and 5 are externally covered by guard members 37a.

[0049] The pump section 10 includes a cylindrical casing 11 that houses the impeller 3. The casing 11 defines a pump chamber 10A therein that pressurizes the liquid using the impeller 3. The casing 11 includes an intermediate casing 11a, an upper casing 11b disposed above the intermediate casing 11a, a lower casing 11c disposed below the intermediate casing 11a, and an outer casing 11d disposed radially outward from the intermediate casing 11a and the upper casing 11b.

[0050] The intermediate casing 11a is formed into a cylindrical shape with a bottom by press-forming a steel plate or the like, and has an opening in the center of the bottom through which the rotating shaft 2 is inserted. The intermediate casings 11a are stacked in multiple tiers according to the number of impellers 3. A suction plate 13 is attached by welding to the underside of the bottom of the intermediate casing 11a. Return vanes 14 are also attached by welding to the underside of the suction plate 13. A liner ring 15 is attached to the inner wall of the bottom opening of the intermediate casing 11a to prevent liquid from leaking to the suction side of the impeller 3.

[0051] The upper casing 11b is formed in a cylindrical shape with a bottom, similar to the intermediate casing 11a, and is stacked on top of the intermediate casing 11a. A plurality of communication holes 11b1 are formed in the peripheral wall of the upper casing 11b. The outer casing 11d is formed in a cylindrical shape that surrounds the radially outer sides of the intermediate casing 11a and the upper casing 11b. The outer casing 11d forms an annular flow path that communicates with the communication holes 11b1 on the radially outer sides of the intermediate casing 11a and the upper casing 11b.

[0052] The lower casing 11c has an inlet 10a that communicates with the center of the bottom of the lowest intermediate casing 11a (the suction side of the impeller 3), and an outlet 10b that communicates with the annular flow path inside the outer casing 11d. The inlet 10a and the outlet 10b are arranged back-to-back on the same straight line on the lower side surface of the pump section 10. The lower casing 11c supports the lower ends of the intermediate casing 11a and the outer casing 11d.

[0053] A pump base 12 is provided below the lower casing 11c. The pump base 12 is axially connected to a coupling 30 by a plurality of casing bolts and nuts (not shown). The multi-stage intermediate casing 11a, upper casing 11b, and lower casing 11c are clamped in the axial direction by fastening the plurality of casing bolts and nuts (not shown).

[0054] In the pump section 10 configured as described above, when the impeller 3 rotates, liquid (fluid) is sucked into the lower casing 11c through the suction port 10a. The liquid sucked into the lower casing 11c is pressurized by the first-stage impeller 3 in the lowest intermediate casing 11a. The liquid discharged from the first-stage impeller 3 passes through a flow path formed by the return vanes 14 and the suction plate 13 and is guided to the suction side of the next-stage impeller 3.

[0055] In this way, the liquid is pressurized in multiple stages by the multiple impellers 3 and flows into the upper casing 11b. The upper casing 11b is formed with multiple communication holes 11b1, and the liquid in the upper casing 11b flows downward from the communication holes 11b1 through an annular flow path formed on the outside of the upper casing 11b and is discharged to the outside from the discharge port 10b of the lower casing 11c.

[0056] 5 and 6, the impeller 3 has a first joint 141 arranged on the negative pressure surface 3c1 side of the blade 3c, and a second joint 142 arranged on the positive pressure surface 3c2 side of the blade 3c and smaller than the first joint 141. With this configuration, the second joint 142 that protrudes toward the positive pressure surface 3c2 side of the blade 3c is small, so the flow path resistance of the impeller 3 that guides the liquid radially outward can be reduced. In addition, the second joint 142 has a flat portion, which makes it difficult for vortices and stagnation of the liquid to occur, improving the performance of the pump 1.

[0057] As described above, the metal joined body 100 according to this embodiment includes the metal plates 110, 130 (first metal plates), the metal plate 120 (second metal plate) butted against the metal plates 110, 130 in a T-shape, and a joint 140 that joins the metal plates 110, 130 to the metal plate 120, and the joint 140 includes a first joint 141 arranged on one surface 121 of the metal plate 120, and a second joint 142 arranged on the other surface 122 of the metal plate 120 and smaller than the first joint 141. This configuration can reduce the flow path resistance on the other surface 122 side of the metal plate 120.

[0058] In the present embodiment, the second bonding portion 142 includes a flat portion. With this configuration, when the metal bonded body 100 of the present embodiment is applied to a fluid machine, vortices or stagnation of the fluid are less likely to occur on the other surface 122 of the metal plate 120, thereby improving the performance of the fluid machine.

[0059] In this embodiment, the flat portions include a first flat portion 142a that follows the metal plates 110 and 130 and a second flat portion 142b that follows the metal plate 120. This configuration can suppress the occurrence of vortices and stagnation of the fluid on the surfaces of the metal plates 110 and 130 and the surface of the metal plate 120.

[0060] In this embodiment, the angle between the first flat portion 142 a and the second flat portion 142 b is a right angle. With this configuration, there is no convex shape on the other surface 122 of the metal plate 120, so the flow path resistance can be further reduced.

[0061] The impeller 3 according to this embodiment includes the metal joined body 100, in which the metal plates 110 and 130 form at least one of the main plate 3 a and the side plate 3 b, and the metal plate 120 forms a plurality of blades 3 c joined to the main plate 3 a and the side plate 3 b, with the second joining portion 142 disposed on the pressure surface 3 c 2 side of each blade 3 c and the first joining portion 141 disposed on the suction surface 3 c 1 side of each blade 3 c. This configuration can reduce the flow path resistance of the impeller 3.

[0062] Furthermore, the pump 1 according to this embodiment includes the impeller 3. With this configuration, the performance of the pump 1 can be improved.

[0063] In addition, the manufacturing method of the metal joined body 100 according to this embodiment involves butting the metal plate 120 against the metal plate 110 in a T-shape and performing projection welding, thereby forming a first joint 141 on one surface 121 of the metal plate 120, and forming a second joint 142, smaller than the first joint 141, on the other surface 122 of the metal plate 120.

[0064] In this embodiment, projection welding is performed with the ceramic plate 300 in contact with the other surface 122 of the metal plate 120, and then the ceramic plate 300 is removed. This method makes it possible to manufacture the metal joined body 100 having a flat portion. Furthermore, the ceramic plate 300 is not welded to the metal plate 120 or the like during projection welding, and is therefore easy to remove.

[0065] As described above, according to the present embodiment, it is possible to provide the metal joined body 100, the impeller 3, the pump 1, and the method for manufacturing the metal joined body 100, which are capable of reducing fluid resistance.

[0066] While preferred embodiments of the present invention have been described and illustrated, it should be understood that these are illustrative of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the present invention should not be deemed limited by the foregoing description, but rather by the scope of the claims.

[0067] For example, in Fig. 7, the impeller 3 including the metal joined body 100 is applied to a vertical multistage pump, but it may also be applied to other centrifugal pumps. Furthermore, the metal joined body 100 may be applied only between the main plate 3a and the blades 3c shown in Fig. 6, or only between the side plate 3b and the blades 3c. Furthermore, the metal joined body 100 may be applied not only to the impeller 3 but also to other fluid machines and fluid components.

[0068] DESCRIPTION OF SYMBOLS 1 Pump 2 Rotating shaft 3 Impeller 3a Main plate 3b Side plate 3c Blade 3c1 Negative pressure surface 3c2 Positive pressure surface 4 Coupling 5 Coupling 6 Rotating shaft 10 Pump section 10a Suction port 10A Pump chamber 10b Discharge port 11 Casing 11a Intermediate casing 11b Upper casing 11b1 Communication hole 11c Lower casing 11d Outer casing 12 Pump base 13 Suction plate 14 Blade 15 Liner ring 30 Coupling section 37a Guard member 100 Metal joint 110 Metal plate (first metal plate) 111 Upper surface 112 Lower surface 120 Metal plate (second metal plate) 121 One surface 122 Other surface 123 Upper end surface 124 Lower end surface 125 Protrusion 130 Metal plate (first metal plate) 131 Upper surface 132 Lower surface 140 Joint portion 141 First joint portion 142 Second joint portion 142a First flat portion 142b Second flat portion 200 Jig 201 Housing groove 210 Electrode 220 Electrode 300 Ceramic plate 301 One surface 302 Other surface 303 Upper end surface 310 Insulating material 330 Convex portion

Claims

1. A metal joined body comprising: a first metal plate; a second metal plate butted against the first metal plate in a T-shape; and a joint joining the first metal plate and the second metal plate, the joint comprising: a first joint arranged on one surface of the second metal plate; and a second joint arranged on the other surface of the second metal plate, the second joint being smaller than the first joint.

2. The metal joint body according to claim 1, wherein the second joint portion has a flat portion.

3. The metal joined body according to claim 2, wherein the planar portion comprises: a first planar portion extending along the first metal plate; and a second planar portion extending along the second metal plate.

4. The metal joint body according to claim 3, wherein the angle between the first flat portion and the second flat portion is a right angle.

5. An impeller comprising the metal joined body according to any one of claims 1 to 4, wherein the first metal plate forms at least one of a main plate and a side plate, the second metal plate forms a plurality of blades joined to the main plate and the side plate, the second joint portion is disposed on the pressure side of the blade, and the first joint portion is disposed on the suction side of the blade.

6. A pump comprising the impeller according to claim 5.

7. A method for manufacturing a metal joint, comprising: butting a second metal plate against a first metal plate in a T-shape and performing projection welding to form a first joint on one surface of the second metal plate; and forming a second joint, smaller than the first joint, on the other surface of the second metal plate.

8. The method for producing a metal joined body according to claim 7, wherein the projection welding is performed with a ceramic plate in contact with the other surface of the second metal plate, and then the ceramic plate is removed.

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