US20140056677A1 - Boom for construction machine - Google Patents

Boom for construction machine Download PDF

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Publication number
US20140056677A1
US20140056677A1 US13/994,821 US201113994821A US2014056677A1 US 20140056677 A1 US20140056677 A1 US 20140056677A1 US 201113994821 A US201113994821 A US 201113994821A US 2014056677 A1 US2014056677 A1 US 2014056677A1
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US
United States
Prior art keywords
plate
boom
web
welding
lower flange
Prior art date
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Abandoned
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US13/994,821
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English (en)
Inventor
Takeshi Takahashi
Atsushi Hamada
Takayuki Shimodaira
Hikaru Yamamoto
Makoto Sugaya
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Hitachi Construction Machinery Co Ltd
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Hitachi Construction Machinery Co Ltd
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Publication date
Application filed by Hitachi Construction Machinery Co Ltd filed Critical Hitachi Construction Machinery Co Ltd
Assigned to HITACHI CONSTRUCTION MACHINERY CO., LTD. reassignment HITACHI CONSTRUCTION MACHINERY CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HAMADA, ATSUSHI, SHIMODAIRA, TAKAYUKI, SUGAYA, MAKOTO, TAKAHASHI, TAKESHI, YAMAMOTO, HIKARU
Publication of US20140056677A1 publication Critical patent/US20140056677A1/en
Abandoned legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/38—Cantilever beams, i.e. booms;, e.g. manufacturing processes, forms, geometry or materials used for booms; Dipper-arms, e.g. manufacturing processes, forms, geometry or materials used for dipper-arms; Bucket-arms

Definitions

  • the present invention relates to a boom for a construction machine, the boom suitably used, as a working arm, in a working mechanism of a hydraulic excavator, for example.
  • a working mechanism provided in a construction machine such as a hydraulic excavator is formed of a boom that is coupled, at the base end side thereof, to a frame of a vehicle body side in such a way that the boom can move upward and downward, an arm that is rotatably coupled to the distal end side of the boom, a working tool such as an excavating bucket that is rotatably coupled to the distal end side of the arm, a boom cylinder, an arm cylinder, and a working tool cylinder that operate the boom, the arm, and the working tool, respectively.
  • the boom is formed as a box shape structural body formed of left and right web plates, an upper flange plate joined to the upper end sides of the left and right web plates by welding, and a lower flange plate joined to the lower end sides of the left and right web plates by welding, the box shape structural body being a closed section structure which is quadrangular in cross section.
  • the boom forms a working arm for a construction machine, and the working arm is a long welded structure with an overall length of several meters or more.
  • Patent Document 1 a method for assembling a long boom by dividing the boom into three parts in a length direction and manufacturing them as three box shape structural body in advance and then joining the box shape structural body to one another in a front-rear direction by welding has been known (Patent Document 1).
  • the boom by the conventional art has to be formed to have a solid structure because the boom is under an impactive load due to the excavation reaction force generated at the time of excavation operation to excavate earth and sand, for example, and great bending moment, torsional moment, and the like are applied thereto. It is for this reason that the bending strength, the torsional strength, and the like of the left and right web plates and the upper and lower flange plates which form the boom are also heightened by increasing the plate thicknesses thereof.
  • the present invention has been made in view of the above-described problems of the conventional art, and an object of the present invention is to provide a boom for the construction machine, the boom that can achieve reduction in weight by reducing the overall weight while ensuring sufficient bending strength, torsional strength, and the like.
  • the present invention is applied to a boom for the construction machine including: left and right web plates; an upper flange plate that is joined to upper end sides of the left and right web plates by welding; and a lower flange plate that is joined to lower end sides of the left and right web plates by welding, the boom is formed of the left and right web plates and the upper and lower flange plates, and formed as the box shape structural body being a closed section structure which is quadrangular in cross section.
  • a feature of the configuration adopted by the invention of claim 1 is that the left web plate and the right web plate are each formed by joining a total of at least five plate materials having different shapes at edge portions in a front-rear direction along welding lines, the upper flange plate is formed by joining a total of at least three plate materials having different shapes at edge portions in a front-rear direction along welding lines, the lower flange plate is formed by joining a total of at least six plate materials having different shapes at edge portions in a front-rear direction along welding lines, end portions of the welding lines between the plate materials forming the upper flange plate and end portions of the welding lines between the plate materials forming the left and right web plates are disposed in positions that are different from one another in a front-rear direction, and end portions of the welding lines between the plate materials forming the lower flange plate and the end portions of the welding lines between the plate materials forming the left and right web plates are disposed in positions that are different from one another in a front-rear direction.
  • the left web plate and the right web plate can be formed by joining a total of at least five plate materials having different shapes at edges in a front-rear direction along welding lines.
  • the upper flange plate can be formed by joining a total of at least three plate materials having different shapes at edges in a front-rear direction along welding lines
  • the lower flange plate can be formed by joining a total of at least six plate materials having different shapes at edges in a front-rear direction along welding lines.
  • the end portions of the welding lines between the plate materials forming the left and right web plates can be disposed in positions that are different, in a front-rear direction, from the positions of the end portions of the welding lines between the plate materials forming the upper flange plate and the end portions of the welding lines between the plate materials forming the lower flange plate.
  • the present invention adopts a configuration in which, a boom foot-side mounting member that is located on a rear end side in a front-rear direction and is welded between the upper and lower flange plates, and a boom cylinder mounting member that is welded to the plate material located in the middle-most of the five plate materials in a front-rear direction, and a boom cylinder is rotatably coupled thereto, are provided between the left and right web plates, and of the five plate materials forming the left and right web plates, the plate thicknesses of the plate material on the rear end side to which the boom foot-side mounting member is welded, and the plate material located in the middle are made greater than the plate thicknesses of the other three plate materials.
  • the plate material in which the boom foot-side mounting member is provided a thick plate material can be used, and, for the other three plate materials, a thin plate material can be used.
  • the plate material on the rear end side can support the boom foot-side mounting member with a solid structure with the upper and lower flange plates, making it possible to increase the support strength.
  • the plate material located in the middle can support, with a solid structure, the boom cylinder mounting member to which the boom cylinder is rotatably coupled, making it possible to increase the support strength.
  • the present invention adopts a configuration in which, a boom foot-side mounting member that is located on a rear end side in a front-rear direction and is welded between the upper and lower flange plates, and a boom cylinder mounting member that is welded to the plate material located in the middle-most of the five plate materials in a front-rear direction and a boom cylinder is rotatably coupled thereto, are provided between the left and right web plates, an arm cylinder mounting member which is located in a position closer to a front side than the boom cylinder mounting member and in a top face of the plate material located in the middle of the three plate materials, and an arm cylinder is rotatably coupled thereto, is provided in the upper flange plate, and in the plate material located in the middle of each of the left and right web plates, the welding line on a rear side in a front-rear direction is disposed so as to be nearly orthogonal to a first reference line connecting the boom foot-side mounting member and the boom cylinder mounting member and the welding line on a
  • the welding line between the plate material located in the middle and the adjacent plate material joined to the rear end portion thereof can be disposed in a position that is nearly orthogonal to the first reference line. This makes it possible to increase the welding strength between the plate material located in the middle and the adjacent plate material located on a rear side to the stress that is produced between the boom cylinder mounting member to which the boom cylinder is coupled and the boom foot-side mounting member.
  • the welding line between the plate material located in the middle and another adjacent plate material joined to the rear end portion thereof can be disposed in a position that is nearly orthogonal to the second reference line. This makes it possible to increase the welding strength between the plate material located in the middle and the other adjacent plate material to the stress that is produced between the boom cylinder mounting member to which the boom cylinder is coupled and the arm cylinder mounting member to which the arm cylinder is coupled.
  • the present invention adopts a configuration in which the left and right web plates are each formed of a total of five plate materials, such as, a first web material located on a rear end side in a front-rear direction, a second web material whose rear end portion is joined to a front end portion of the first web material, a third web material whose rear end portion is joined to a front end portion of the second web material, a fourth web material whose rear end portion is joined to a front end portion of the third web material, and a fifth web material whose rear end portion is joined to a front end portion of the fourth web material, and between the second web materials forming the left and right web plates, a first partition plate is provided so as to be located between the upper and lower flange plates, and, between the fourth web materials, a second partition plate is provided so as to be located between the upper and lower flange plates.
  • a first partition plate is provided so as to be located between the upper and lower flange plates
  • a second partition plate is provided so as to be located between
  • the first partition plate can be provided by being joined by welding so as to be located between the upper and lower flange plates, and, with the first partition plate, it is possible to increase the joint strength between the left and right web plates and the upper and lower flange plates by welding.
  • the second partition plate can be provided by being joined by welding so as to be located between the upper and lower flange plates, and, with the second partition plate, it is possible to increase the joint strength between the left and right web plates and the upper and lower flange plates by welding.
  • the present invention adopts a configuration in which, an arm-side mounting member that is located on a front end side in a front-rear direction and is welded between the upper and lower flange plates is provided in the left and right web plates.
  • This makes it possible to provide the arm-side mounting member between an area located on a front end side of the entire length of the left and right web plates and the upper and lower flange plates by joining the arm-side mounting member therebetween by welding and rotatably couple an arm to the distal end side of the boom with the arm-side mounting member.
  • FIG. 1 is a front view showing a hydraulic excavator in which a boom according to a first embodiment of the present invention is provided.
  • FIG. 2 is a front view showing the boom in FIG. 1 as a single unit.
  • FIG. 3 is a partially enlarged view of FIG. 2 , showing a middle portion of the boom in a length direction thereof.
  • FIG. 4 is an exploded perspective view showing plate materials forming the boom.
  • FIG. 5 is an exploded perspective view of the boom, showing a state in which the plate materials forming a web plate and an upper flange plate in FIG. 2 are joined, respectively.
  • FIG. 6 is a perspective view showing a state in which the left and right web plates and the upper flange plate are integrally assembled by welding.
  • FIG. 7 is a perspective view showing a state in which internal welding is performed on the inner surfaces of the left and right web plates and the upper flange plate, which was integrally assembled.
  • FIG. 8 is a perspective view showing a state in which a lower flange plate is joined to the left and right web plates, which were integrally assembled.
  • FIG. 9 is a perspective view showing a state in which external welding is performed, by robots, on the left and right web plates and the upper and lower flange plates, which were, integrally assembled.
  • FIG. 10 is an exploded perspective view showing plate materials forming a boom according to a second embodiment.
  • FIGS. 1 to 9 show a boom of a hydraulic excavator according to a first embodiment of the present invention.
  • a hydraulic excavator as a construction machine, and, as shown in FIG. 1 , the hydraulic excavator 1 is largely constituted by an automotive crawler-type lower traveling structure 2 , an upper revolving structure 3 rotatably mounted on the lower traveling structure 2 , and a working mechanism 8 which will be described later.
  • the upper revolving structure 3 of the hydraulic excavator 1 forms a vehicle body of the construction machine with the lower traveling structure 2 .
  • the upper revolving structure 3 is formed of a revolving frame 4 , a cab 5 , a counterweight 6 , a housing cover 7 , and the like, which will be described later.
  • the revolving frame forming a frame of the upper revolving structure 3
  • the working mechanism 8 which will be described later is liftably attached on the front side of the revolving frame 4
  • the counterweight 6 which will be described later is attached on its rear side.
  • the cab 5 is disposed in the left front portion of the revolving frame 4 , and the cab 5 defines an operator's room inside.
  • an operator's seat in which an operator sits, an operating lever, a lever or pedal for travelling (none of which is illustrated), and the like are disposed therein.
  • the counterweight provided on a rear end side of the revolving frame 4 , and the counterweight 6 is detachably mounted on the rear end side of the revolving frame 4 to keep a weight balance of the entire upper revolving structure 3 with respect to the working mechanism 8 on the front side.
  • the housing cover 7 In front side of the counterweight 6 , the housing cover 7 , which will be described later, that accommodates an engine (not shown) and the like is provided.
  • the housing cover 7 is located between the cab 5 and the counterweight 6 and is vertically provided on the revolving frame 4 .
  • the housing cover 7 is formed in a housing structure by using a plurality of metal panels and the like formed of a thin steel sheet, for example, and defines a machine room (not shown) accommodating the engine and the like, therein.
  • Designated at 8 is the working mechanism liftably provided in the front portion of the upper revolving structure 3 , and the working mechanism 8 is largely constituted by a boom 11 which will be described later, an arm 9 that is liftably attached to the distal end side of the boom 11 , and a bucket 10 , as a working tool, that is rotatably provided at the distal end side of the arm 9 to perform excavation operation on earth and sand, for example.
  • the boom 11 of the working mechanism 8 is moved upward and downward with respect to the revolving frame 4 by a boom cylinder 11 A, and the arm 9 is moved upward and downward by an arm cylinder 9 A at the distal end side of the boom 11 .
  • the bucket 10 as the working tool is rotated up and down by a bucket cylinder 10 A at the distal end side of the arm 9 .
  • Designated at 11 is the boom forming a working arm of the working mechanism 8 , and the boom 11 is formed as a long box shape structural body as shown in FIG. 1 and is moved upward and downward with respect to the revolving frame 4 by the boom cylinder 11 A.
  • the boom 11 is formed of a pair of left and right web plates 12 and 12 extending in a length direction (a front-rear direction) of the boom 11 and facing each other in a left-right direction and upper and lower flange plates 14 and 16 joined to both upper and lower end sides of each of the web plates 12 by welding, and the boom 11 is formed as the box shape structural body being a closed section structure which is quadrangular in cross section.
  • the left and right web plates 12 and the upper and lower flange plates 14 and 16 are formed by using a plate material made of high-tensile steel in the 550 to 600 Mpa (megapascals) class, for example, making it possible to minimize the plate thickness of each plate material.
  • partition plates 18 and 19 , boss members 20 and 21 , and bracket members 22 and 23 which will be described later, are also formed by using steel made of similar high-tensile steel.
  • Indicated at 12 is a pair of left and right web plates forming the side faces of the boom 11 .
  • the left web plate 12 and the right web plate 12 are formed so as to have the same shape, one web plate 12 will be explained.
  • a rear end side in a front-rear direction which is a length direction of the boom 11 corresponds to a rear side of the boom 11 when viewed from the backward of the vehicle of the hydraulic excavator 1
  • a front end side in a front-rear direction corresponds to a front side (a distal end side) of the boom 11 when viewed from the backward of the vehicle of the hydraulic excavator 1 .
  • the web plate 12 is formed of a total of five plate materials such as a first web material 12 A located on the rear end side (the foot side of the boom 11 ) of the entire length of the web plate 12 and a second web material 12 B, a third web material 12 C, a fourth web material 12 D, and a fifth web material 12 E which are located in order in front of the first web material 12 A and have different shapes.
  • the first web material 12 A located at the rearmost end in a front-rear direction is formed in the shape of a quadrangle whose vertical width is gradually increased with distance from the rear side as it gets near the front side by performing press forming on a flat plate material made of the high-tensile steel. Furthermore, the first web material 12 A is bent in the position of a bending line 12 A 1 closer to the front side in such a way that the first web material 12 A is curved to the outside in a left-right direction.
  • the next second web material 12 B is also formed in the shape of a quadrangle whose vertical width is gradually increased with distance from the rear side as it gets near the front side by performing press forming on a flat plate material made of the high-tensile steel.
  • the third web material 12 C located in the middle-most in a front-rear direction is formed in the shape of a parallelogram as shown in FIG. 2 by performing press forming on a flat plate material made of the high-tensile steel. Furthermore, both upper and lower end sides of the third web material 12 C are arc-shaped edge portions 12 C 1 and 12 C 2 , each having a previously determined curvature. Of the edge portions 12 C 1 and 12 C 2 , the upper edge portion 12 C 1 is formed so as to have a radius of curvature of about 1800 mm, for example, and the lower edge portion 12 C 2 is also formed so as to have a substantially similar radius of curvature.
  • a circular punching hole 12 C 3 is formed between the edge portions 12 C 1 and 12 C 2 , and, to the punching hole 12 C 3 , an annular flange portion 21 B of the boss member 21 , which will be described later, is joined by welding.
  • the fourth web material 12 D is formed in the shape of a trapezoid with an upper base longer than a lower base by performing press forming on a flat plate material made of the high-tensile steel. Therefore, the boom 11 has a shape whose middle portion in a length direction is curved in an arched shape by the presence of the third web materials 12 C and the fourth web materials 12 D of the left and right web plates 12 .
  • the fifth web material 12 E located at the forefront (the front end side) in a front-rear direction is formed in the shape of a quadrangle whose vertical width is gradually decreased with distance from the rear side as it gets near the front side by performing press forming on a flat plate material made of the high-tensile steel.
  • the fifth web material 12 E is formed so as to have the greatest length in a front-rear direction and the smallest plate thickness.
  • the second web material 12 B is joined, at a rear end portion thereof, to a front end portion of the first web material 12 A along a welding line 13 A.
  • the welding line 13 A In the position of the welding line 13 A, butt welding with a V-shaped groove is performed, and the welding line 13 A has one end portion 13 A 1 and the other end portion 13 A 2 .
  • the third web material 12 C is joined, at a rear end portion thereof, to a front end portion of the second web material 12 B along a welding line 13 B. Also in the position of the welding line 13 B, butt welding with a V-shaped groove is performed, and the welding line 13 B has one end portion 13 B 1 and the other end portion 13 B 2 .
  • the fourth web material 12 D is joined, at a rear end portion thereof, to a front end portion of the third web material 12 C along a welding line 13 C. Also in the position of the welding line 13 C, butt welding with a V-shaped groove is performed, and the welding line 13 C has one end portion 13 C 1 and the other end portion 13 C 2 . Furthermore, the fifth web material 12 E is joined, at a rear end portion thereof, to a front end portion of the fourth web material 12 D along a welding line 13 D. Also in the position of the welding line 13 D, butt welding with a V-shaped groove is performed, and the welding line 13 D has one end portion 13 D 1 and the other end portion 13 D 2 .
  • the first web material 12 A and the third web material 12 C share the greatest load, and, as an example, the plate thickness t 1 a of the first web material 12 A and the plate thickness t 1 c of the third web material 12 C are formed so as to be about 14 mm, for example.
  • the plate thickness t 1 b of the second web material 12 B and the plate thickness t 1 d of the fourth web material 12 D are formed so as to be about 10 mm, for example.
  • the plate thickness t 1 e of the fifth web material 12 E is about 9 mm, for example, and is formed so as to be the smallest thickness. Therefore, the plate thicknesses t 1 a to t 1 e of the first to fifth web materials 12 A to 12 E have the following relationship.
  • the welding line 13 B between the second web material 12 B and the third web material 12 C is disposed in a position forming an angle ⁇ 1 (for example, ⁇ 1 ⁇ 4.5 to 4.9 degrees) with a first orthogonal line A-A, which will be described later, in a range close thereto.
  • the welding line 13 C between the third web material 12 C and the fourth web material 12 D is disposed in a position forming an angle ⁇ 2 (for example, ⁇ 2 ⁇ 10.5 to 11.5 degrees) with a second orthogonal line B-B, which will be described later, in a range close thereto.
  • a point of intersection of the upper edge portion 12 C 1 of the third web material 12 C and the end portion 13 C 1 of the welding line 13 C is disposed in a position closer to the front than a rear end portion of the bracket member 23 , which will be described later, by a dimension a (for example, ⁇ 113 to 116 mm).
  • the upper flange plate 14 is formed of a total of three plate materials such as a rear upper flange material 14 A which is located on the rear side in a front-rear direction of the entire length of the upper flange plate 14 , a front upper flange material 14 B located on the front side in a front-rear direction, and a middle upper flange material 14 C disposed between the rear upper flange material 14 A and the front upper flange material 14 B.
  • the middle upper flange material 14 C is disposed in a position in which the middle upper flange material 14 C covers the boss member 21 , which will be described later, from above.
  • the rear upper flange material 14 A, the front upper flange material 14 B, and the middle upper flange material 14 C are each formed in the shape of a quadrangle by performing press forming on a flat plate material made of the high-tensile steel, have different shapes, and extend in a front-rear direction.
  • the rear upper flange material 14 A has the shortest length dimension
  • the middle upper flange material 14 C has the longest thereof
  • the front upper flange material 14 B is formed so as to be intermediate in length dimension between the rear upper flange material 14 A and the middle upper flange material 14 C.
  • the plate thickness t 2 c of the middle upper flange material 14 C is the greatest thickness and is formed so as to be a plate thickness of about 14 mm, for example.
  • the plate thickness t 2 a of the rear upper flange material 14 A is formed so as to be an intermediate plate thickness of about 10 mm, for example, and the plate thickness t 2 b of the front upper flange material 14 B is about 8 mm, for example, and is formed so as to be the smallest thickness.
  • the plate thickness t 2 a of the rear upper flange material 14 A, the plate thickness t 2 b of the front upper flange material 14 B, and the plate thickness t 2 c of the middle upper flange material 14 C have the following relationship.
  • the middle upper flange material 14 C is joined, at a rear end portion thereof, to a front end portion of the rear upper flange material 14 A along a welding line 15 A.
  • Butt welding with a V-shaped groove is performed in the position of the welding line 15 A, and the welding line 15 A has one end portion 15 A 1 and the other end portion 15 A 2 .
  • the front upper flange material 14 B is joined, at a rear end portion thereof, to a front end portion of the middle upper flange material 14 C along a welding line 15 B.
  • Butt welding with a V-shaped groove is performed also in the position of the welding line 15 B, and the welding line 15 B has one end portion 15 B 1 and the other end portion 15 B 2 .
  • the upper flange plate 14 is curved as shown in FIG. 5 . That is, the rear upper flange material 14 A and the middle upper flange material 14 C of the upper flange plate 14 are curved into a shape that follows the arc-shaped contour of the upper end side of the web plate 12 .
  • the upper flange plate 14 formed of the rear upper flange material 14 A, the front upper flange material 14 B, and the middle upper flange material 14 C is joined to the upper end sides of the left and right web plates 12 by welding.
  • the welding lines 13 A, 13 B, 13 C, and 13 D of the web plates 12 are disposed in such a way that the welded positions of the end portions 13 A 1 , 13 B 1 , 13 C 1 , and 13 D 1 thereof do not overlap the welded positions of the end portions 15 A 1 and 15 B 1 (the end portions 15 A 2 and 15 B 2 ) of the welding lines 15 A and 15 B of the upper flange plate 14 .
  • the end portions 13 A 1 , 13 B 1 , 13 C 1 , and 13 D 1 of the welding lines 13 A to 13 D and the end portions 15 A 1 and 15 B 1 (the end portions 15 A 2 and 15 B 2 ) of the welding lines 15 A and 158 are disposed in positions that are different from each other in a front-rear direction of the boom 11 .
  • the lower flange plate 16 is formed of a total of six plate materials which are disposed so as to be arranged in order from the rear side to the front side in a front-rear direction of the entire length of the lower flange plate 16 , such as a first lower flange material 16 A, a second lower flange material 16 B, a third lower flange material 16 C, a fourth lower flange material 16 D, a fifth lower flange material 16 E, and a sixth lower flange material 16 F.
  • the third lower flange material 16 C is disposed in a position below the boss member 21 which will be described later.
  • the lower flange materials 16 A to 16 F are each formed in the shape of a quadrangle by performing press forming on a flat plate material made of the high-tensile steel, have different shapes, and extend in a front-rear direction.
  • the third lower flange material 16 C located in the middle in a front-rear direction is formed so as to be the longest, and the second lower flange material 16 B and the sixth lower flange material 16 F are formed so as to be the shortest.
  • the fourth lower flange material 16 D is formed so as to be longer than the second and sixth lower flange materials 16 B and 16 F.
  • the first lower flange material 16 A and the fifth lower flange material 16 E are formed so as to be shorter than the third lower flange material 16 C and longer than the fourth lower flange material 16 D.
  • the plate thickness t 3 c of the third lower flange material 16 C located in the middle in a front-rear direction is the greatest thickness and is formed so as to be about 12 mm, for example.
  • the plate thicknesses t 3 a and t 3 b of the first and second lower flange materials 16 A and 16 B are formed so as to be about 9 mm, for example.
  • the plate thicknesses t 3 d , t 3 e , and t 3 f of the fourth, fifth, and sixth lower flange materials 16 D, 16 E, and 16 F are about 8 mm, for example, and are formed so as to be the smallest thickness. Therefore, the plate thicknesses t 3 a to t 3 f of the first to sixth lower flange materials 16 A to 16 F have the following relationship.
  • the welding line 17 A has one end portion 17 A 1 and the other end portion 17 A 2 . As shown in FIG. 4 , rolling process before joining the plates is performed on the third lower flange material 16 C, and the third lower flange material 16 C is curved into a shape that follows the arc-shaped contour of the lower end side of the web plate 12 . Then, a front end portion of the third lower flange material 16 C is joined to a rear end portion of the fourth lower flange material 16 D along a welding line 17 A, and butt welding with a V-shaped groove is performed in the position of the welding line 17 A. As shown in FIG. 5 , the welding line 17 A has one end portion 17 A 1 and the other end portion 17 A 2 . As shown in FIG.
  • the third lower flange material 16 C and the fourth lower flange material 16 D which were joined to each other are joined, by welding, to the left and right web plates 12 which were integrally assembled and welded to the upper flange plate 14 , in such a way as to close partially a lower end side of a middle part thereof in a length direction.
  • the short length second lower flange material 16 B and the short length sixth lower flange material 16 F are joined to the left and right web plates 12 by welding in such a way as to close partially the lower end side thereof.
  • a rear end portion of the second lower flange material 16 B is joined to a front end portion of the third lower flange material 16 C along a welding line 17 B (see FIG. 9 ), and, in the position of the welding line 17 B, both side welding of the inside and the outside is performed in a state in which they are butted.
  • the welding line 17 B has one end portion 17 B 1 and the other end portion 17 B 2 .
  • the first lower flange material 16 A and the fifth lower flange material 16 E form a lid member that finally closes the openings between each web plates 12 of a boom assembly body 31 which will be described later. That is, when assembling welding is performed on the boom 11 forming a quadrangular closed section structure, the first lower flange material 16 A and the fifth lower flange material 16 E are joined to the left and right web plates 12 by welding in such a way as to close the lower end side thereof finally. At this time, a rear end portion of the first lower flange material 16 A is joined to a front end portion of the second lower flange material 16 B along a welding line 17 C (see FIG.
  • the welding line 17 C has one end portion 17 C 1 and the other end portion 17 C 2 .
  • a rear end portion of the fifth lower flange material 16 E is joined to a front end portion of the fourth lower flange material 16 D along a welding line 17 D
  • a front end portion of the fifth lower flange material 16 E is joined to a rear end portion of the sixth lower flange material 16 F along a welding line 17 E.
  • butt welding with a V-shaped groove using a backing material is performed in the positions of the welding lines 17 D and 17 E.
  • the welding line 17 D has one end portion 17 D 1 and the other end portion 17 D 2
  • the welding line 17 E has one end portion 17 E 1 and the other end portion 17 E 2 .
  • the welding line 17 A of the lower flange plate 16 is disposed in such a way that the welded positions of the end portions 17 A 1 and 17 A 2 thereof do not overlap the welded positions of the end portions 13 C 2 and 13 D 2 of the welding lines 13 C and 13 D of the left and right web plates 12 . That is, the end portions 13 C 2 and 13 D 2 of the welding lines 13 C and 13 D and the end portions 17 A 1 and 17 A 2 of the welding line 17 A are disposed in positions that are different from one another in a front-rear direction of the boom 11 .
  • the end portions 17 B 1 and 17 B 2 of the welding line 17 B are disposed in such a way that the welded positions thereof do not overlap the welded positions of the end portions 13 A 2 of the welding lines 13 A of the web plates 12 . That is, the end portions 13 A 2 of the welding lines 13 A and the end portions 17 B 1 and 17 B 2 of the welding line 17 B are disposed in positions that are different from one another in a front-rear direction of the boom 11 .
  • the end portions 17 C 1 and 17 C 2 of the welding line 17 C are also disposed in such a way that the welded positions thereof do not overlap the welded positions of the end portions 13 A 2 of the welding lines 13 A of the web plates 12 , for example. That is, the end portions 13 A 2 of the welding lines 13 A and the end portions 17 C 1 and 17 C 2 of the welding line 17 C are disposed in positions that are different from one another in a front-rear direction of the boom 11 .
  • the end portions 17 D 1 and 17 D 2 of the welding line 17 D are also disposed in such a way that the welded positions thereof do not overlap the welded positions of the end portions 13 D 2 of the welding lines 13 D, for example.
  • the end portions 13 D 2 of the welding lines 13 D and the end portions 17 D 1 and 17 D 2 of the welding line 17 D are disposed in positions that are different from one another in a front-rear direction of the boom 11 .
  • the end portions 17 E 1 and 17 E 2 of the welding line 17 E are also disposed in such a way that the welded positions thereof do not overlap the welded positions of the end portions 13 D 2 of the welding lines 13 D, for example. That is, the end portions 13 D 2 of the welding lines 13 D and the end portions 17 E 1 and 17 E 2 of the welding line 17 E are disposed in positions that are different from one another in a front-rear direction of the boom 11 .
  • the first partition plate as a partition wall provided within the boom 11 , and the first partition plate 18 is provided by being joined between the second web materials 12 B forming the left and right web plates 12 and between the upper and lower flange plates 14 and 16 by means of fillet welding or the like.
  • the upper end of the first partition plate 18 is joined to the middle upper flange material 14 C of the upper flange plate 14 by means of fillet welding or the like.
  • the lower end of the first partition plate 18 is joined to the third lower flange material 16 C of the lower flange plate 16 by means of fillet welding or the like.
  • the left and right ends of the first partition plate 18 are joined to the second web materials 12 B of the left and right web plates 12 by means of fillet welding or the like.
  • the second partition plate as a partition wall provided within the boom 11 , and the second partition plate 19 is provided by being joined between the fourth web materials 12 D forming the left and right web plates 12 and between the upper and lower flange plates 14 and 16 by means of fillet welding or the like.
  • the upper end of the second partition plate 19 is joined to the middle upper flange material 14 C of the upper flange plate 14 by means of fillet welding or the like.
  • the lower end of the second partition plate 19 is joined to the third lower flange material 16 C of the lower flange plate 16 by means of fillet welding or the like.
  • the left and right ends of the third partition plate 19 are joined to the fourth web materials 12 D of the left and right web plates 12 by means of fillet welding or the like.
  • the boss member 20 forming the boom foot-side mounting member.
  • the boss member 20 is formed of a tubular boss portion 20 A extending in a left-right direction and left and right connecting portions 20 B which are integrally formed at the both end sides of the boss portion 20 A.
  • the connecting portions 20 B of the boss member 20 are joined to the rear end sides of the first web materials 12 A of the left and right web plates 12 with welding means with a rear V-shaped groove, for example.
  • the rear ends of the upper and lower flange plates 14 and 16 (that is, the rear end of the rear upper flange material 14 A and the rear end of the first lower flange material 16 A) are joined with welding means so as to sandwich the boss portion 20 A in a vertical direction.
  • the boss member 20 is provided so that it is located at the rear end (the base end) side of the boom 11 and welded between the rear ends of the left and right first web materials 12 A, the rear end of the rear upper flange material 14 A, and the rear end of the first lower flange material 16 A.
  • the boss member 20 forms a boom foot portion for liftably pin-coupling the base end side of the boom 11 to the revolving frame 4 (see FIG. 1 ) of the upper revolving structure 3 .
  • the boss member 21 is formed of a tubular boss portion 21 A extending in a left-right direction and left and right annular flange portions 21 B which are integrally formed at the both end sides of the boss portion 21 A.
  • the annular flange portions 21 B of the boss member 21 are fit into the third web materials 12 C of the left and right web plates 12 through the punching holes 12 C 3 and are joined to the areas around the punching holes 12 C 3 by using welding means with a rear V-shaped groove, for example.
  • a rod side of the boom cylinder 11 A is rotatably pin-coupled.
  • each third web material 12 C located in the middle-most in a front-rear direction is disposed in a range close to the first orthogonal line A-A in such a way that the welding line 13 B between the third web material 12 C and the adjacent second web material 12 B is nearly orthogonal to the first reference line L 1 .
  • An angle ⁇ 1 which the first orthogonal line A-A and the welding line 13 B form is set at an angle of 5 degrees or less (for example, ⁇ 1 ⁇ 4.5 to 4.9 degrees).
  • bracket member 22 forming the arm-side mounting member provided on the front end (the tip) side of the boom 11 .
  • the bracket member 22 is formed of a pair of left and right bifurcated bracket portions 22 A and a joint portion 22 B integrally coupling the bracket portions 22 A.
  • the rear ends of the left and right bracket portions 22 A are joined to the front end sides of the left and right fifth web materials 12 E by using welding means with a rear V-shaped groove, for example.
  • the front ends of the upper and lower flange plates 14 and 16 (that is, the front end of the front upper flange material 14 B and the front end of the sixth lower flange material 16 F) are joined with welding means so as to sandwich the joint portion 22 B in a vertical direction.
  • the bracket member 22 is provided so that it is located at the front end (the tip) side of the boom 11 and welded between the front ends of the left and right fifth web materials 12 E, the front end of the front upper flange material 14 B, and the front end of the sixth lower flange material 16 F. As shown in FIG. 1 , to such a bracket member 22 , a base end side of the arm 9 is liftably pin-coupled.
  • bracket member 23 is formed as a bifurcated bracket and has a pin through hole 23 A.
  • the bracket member 23 is joined to a top face side of the middle upper flange material 14 C of the upper flange plate 14 by using means such as fillet welding, for example.
  • a bottom side of the arm cylinder 9 A is rotatably pin-coupled.
  • the hydraulic excavator 1 according to the first embodiment has the configuration described above and the operation thereof will be described hereafter.
  • the operator who got into the cab 5 of the hydraulic excavator 1 operates a lever, a pedal (none of which is illustrated), and the like in the cab 5 and supplies pressurized oil which is discharged from a hydraulic pump (not shown) in the housing cover 7 to the lower traveling structure 2 , thereby driving a traveling motor and the like of the lower traveling structure 2 and moving the vehicle forward and rearward.
  • the boom 11 which forms the working arm of the working mechanism 8 with the arm 9 , will be described with reference to FIGS. 4 to 9 .
  • the left and right web plates 12 and the upper and lower flange plates 14 and 16 which form the boom 11 are produced by press forming in separate processes, respectively.
  • the first to fifth web materials 12 A to 12 E formed by press forming so as to have different shapes are joined together in a front-rear direction along the welding lines 13 A, 13 B, 13 C, and 13 D by butt welding with a V-shaped groove as shown in FIG. 5 .
  • the first web material 12 A at a stage of press forming before the first web material 12 A is joined to the second web material 12 B, the first web material 12 A is bent in the position of the bending line 12 A 1 closer to the front side in such a way that the first web material 12 A is curved to the outside in a left-right direction.
  • the rear upper flange material 14 A, the middle upper flange material 14 C, and the front upper flange material 14 B formed by press forming so as to have different shapes are joined together in a front-rear direction along the welding lines 15 A and 15 B by butt welding with a V-shaped groove.
  • rolling process after joining the plates is performed on the upper flange plate 14 .
  • the rear upper flange material 14 A and the middle upper flange material 14 C of the upper flange plate 14 are curved into a shape that follows the arc-shaped contour of the upper end side of the web plate 12 .
  • the third lower flange material 16 C is curved into a shape that follows the arc-shaped contour of the lower end side of the web plate 12 .
  • the rear end portion of the fourth lower flange material 16 D is integrally joined to the front end portion of the third lower flange material 16 C along the welding line 17 A by butt welding with a V-shaped groove.
  • first lower flange material 16 A, the second lower flange material 16 B, the joined body of the third and fourth lower flange materials 16 C and 16 D, the fifth lower flange material 16 E, and the sixth lower flange material 16 F of the lower flange plate 16 are not joined to one another and are put on standby in predetermined positions until a final stage (a lower flange plate assembly process shown in FIG. 8 ) of assembly operation of the boom 11 is performed.
  • the left and right web plates 12 and the upper flange plate 14 are disposed so as to be temporarily joined.
  • the upper flange plate 14 formed of the rear upper flange material 14 A, the front upper flange material 14 B, and the middle upper flange material 14 C is fixed in such a way as to be temporarily joined to the upper end sides of the left and right web plates 12 by welding.
  • the welding lines 13 A, 13 B, 13 C, and 13 D of the web plates 12 are disposed in positions in which the end portions 13 A 1 , 13 B 1 , 13 C 1 , and 13 D 1 of the welding lines 13 A to 13 D and the end portions 15 A 1 and 15 B 1 (the end portions 15 A 2 and 15 B 2 ) of the welding lines 15 A and 15 B appear alternately in a front-rear direction of the boom 11 , in such a way that the welded positions of the welding lines 13 A to 13 D do not overlap the welded positions of the welding lines 15 A and 15 B of the upper flange plate 14 .
  • the first and second partition plates 18 and 19 are disposed so as to be temporarily joined by welding. That is, the first partition plate 18 is temporarily joined between the left and right second web materials 12 B and to a rear side of the middle upper flange material 14 C by partial welding.
  • the second partition plate 19 is temporarily joined between the left and right fourth web materials 12 D and to a front side of the middle upper flange material 14 C by partial welding.
  • the boss member 20 on the boom foot side is temporarily joined by welding.
  • the boss member 21 for the boom cylinder 11 A is temporarily joined by welding located between the left and right third web materials 12 C. That is, the annular flange portion 21 B of the boss member 21 is temporarily joined to the punching holes 12 C 3 of the third web materials 12 C by welding.
  • the bracket member 22 for the arm 9 is temporarily joined by welding, and, to the top face side of the middle upper flange material 14 C, the bracket member 23 for the arm cylinder 9 A is temporarily joined by welding.
  • the boom assembly body 31 which is a preliminary assembly of the boom 11 .
  • the boom assembly body 31 is formed of the left and right web plates 12 , the upper flange plate 14 , the first and second partition plates 18 and 19 , the boss members 20 and 21 , and the bracket members 22 and 23 which were integrally assembled by being temporarily joined.
  • the boom assembly body 31 is set between a prepared pair of rotating positioners 25 .
  • the boom assembly body 31 is rotated by the pair of rotating positioners 25 in a direction indicated by an arrow C in FIG. 7 , and internal welding is performed on the boom assembly body 31 . That is, internal welding over the entire length in a front-rear direction is performed on the joining parts between the left and right web plates 12 and the upper flange plate 14 .
  • Internal welding for the first partition plate 18 is performed, by means such as fillet welding, on the joining parts between the first partition plate 18 and the left and right second web materials 12 B and the joining part between the first partition plate 18 and the rear side of the middle upper flange material 14 C.
  • internal welding for the second partition plate 19 is performed, by means such as fillet welding, on the joining parts between the second partition plate 19 and the left and right fourth web materials 12 D and the joining part between the second partition plate 19 and the front side of the middle upper flange material 14 C.
  • a joined body of the third lower flange material 16 C and the fourth lower flange material 16 D which were joined together in advance is joined to the left and right web plates 12 of the boom assembly body 31 by welding in such a way as to close partially the lower end side of the middle part thereof in a length direction.
  • the first partition plate 18 is joined, at the lower end side thereof, to an internal face of the third lower flange material 16 C by means such as fillet welding.
  • the second partition plate 19 is also joined, at the lower end side thereof, to the internal face of the third lower flange material 16 C by means such as fillet welding.
  • the second lower flange material 16 B and the sixth lower flange material 16 F of the lower flange plate 16 are joined to the left and right web plates 12 by being welded thereto in such a way as to close partially the lower end side thereof.
  • the rear end portion of the second lower flange material 16 B is joined to the front end portion of the third lower flange material 16 C along the welding line 17 B (see FIG. 9 ), and, in the position of the welding line 17 B, both side welding of the inside and the outside is performed in a state in which they are butted.
  • the front end portion of the sixth lower flange material 16 F is joined to the joint portion 22 B of the bracket member 22 by both side welding of the inside and the outside in a state in which they are butted in a front-rear direction.
  • the first lower flange material 16 A and the fifth lower flange material 16 E are joined to the left and right web plates 12 by being welded thereto in such a way as to close the lower end side thereof, and the assembly operation of the lower flange plate 16 is completed. That is, when the operation to join the first lower flange material 16 A and the fifth lower flange material 16 E is completed, the lower end side of the left and right web plates 12 is practically closed over the entire length thereof in a front-rear direction.
  • the rear end portion of the first lower flange material 16 A is joined to the front end portion of the second lower flange material 16 B along the welding line 17 C (see FIG. 9 ).
  • the rear end portion of the fifth lower flange material 16 E is joined to the front end portion of the fourth lower flange material 16 D along the welding line 17 D
  • the front end portion of the fifth lower flange material 16 E is joined to the rear end portion of the sixth lower flange material 16 F along the welding line 17 E.
  • butt welding with a V-shaped groove using a backing material is performed in the external welding process which will be described later.
  • external welding which is a final stage of the welding process is performed by using a plurality of welding robots 26 .
  • fillet welding is performed, by the welding robots 26 , between the left and right web plates 12 and the upper flange plate 14 over the entire length in a front-rear direction.
  • fillet welding is also performed between the left and right web plates 12 and the lower flange plate 16 over the entire length in a front-rear direction.
  • the bracket member 23 which was temporarily joined thereto in advance is joined more firmly by fillet welding.
  • the rear end portion of the first lower flange material 16 A and the front end portion of the second lower flange material 16 B are joined together along the welding line 17 C, and, in the position of the welding line 17 C, butt welding with a V-shaped groove using a backing material (not shown) is completed.
  • the rear end portion of the fifth lower flange material 16 E and the front end portion of the fourth lower flange material 16 D are also joined together along the welding line 17 D
  • the front end portion of the fifth lower flange material 16 E and the rear end portion of the sixth lower flange material 16 F are also joined together along the welding line 17 E.
  • butt welding with a V-shaped groove using a backing material is completed.
  • the boom 11 is completed as a welded structure formed as a long box shape structural body. Then, the boom 11 is transferred to an assembly process of the working mechanism 8 and is assembled with the arm 9 as the working arm of the working mechanism 8 shown in FIG. 1 , for example.
  • the left and right web plates 12 of the boom 11 can be formed by joining a total of five web materials such as the first to fifth web materials 12 A to 12 E having different shapes at the edges in a front-rear direction along the welding lines 13 A to 13 D.
  • the upper flange plate 14 can be formed by joining a total of three flange materials such as the rear upper flange material 14 A, the front upper flange material 14 B, and the middle upper flange material 14 C having different shapes at the edges in a front-rear direction along the welding lines 15 A and 15 B.
  • the lower flange plate 16 can be formed by joining a total of six flange materials such as the first to sixth lower flange materials 16 A to 16 F having different shapes at the edges in a front-rear direction along the welding lines 17 A to 17 E.
  • the end portions 13 A 1 , 13 B 1 , 13 C 1 , and 13 D 1 located in the upper parts of the welding lines 13 A to 13 D between the plate materials forming the left and right web plates 12 can be disposed in positions which are different, in a front-rear direction, from the positions of the end portions 15 A 1 and 15 B 1 (the end portions 15 A 2 and 15 B 2 ) of the welding lines 15 A and 15 B between the plate materials forming the upper flange plate 14 .
  • the end portions 13 A 2 , 13 B 2 , 13 C 2 , and 13 D 2 located in the lower parts of the welding lines 13 A to 13 D can be disposed in positions which are different, in a front-rear direction, from the positions of the end portions 17 A 1 , 17 B 1 , 17 C 1 , 17 D 1 , and 17 E 1 (the end portions 17 A 2 , 17 B 2 , 17 C 2 , 17 D 2 , and 17 E 2 ) of the welding lines 17 A to 17 E between the plate materials forming the lower flange plate 16 .
  • the first web material 12 A to which the boss member 20 on the boom foot side is joined and the third web plate 12 C located in the middle-most in a front-rear direction use a thick plate material.
  • the other web materials such as the second web material 12 B, the fourth web material 12 D, and the fifth web material 12 E can use a material whose plate thickness is smaller than those of the first web material 12 A and the third web material 12 C.
  • the first web materials 12 A can support the boss member 20 on the boom foot side with a solid structure with the rear upper flange material 14 A of the upper flange plate 14 and the first lower flange material 16 A of the lower flange plate 16 and increase the support strength on the boom foot side.
  • the left and right third web materials 12 C can support the boss member 21 to which the rod side of the boom cylinder 11 A is rotatably pin-coupled with a solid structure and increase the support strength for the boom cylinder 11 A.
  • the third web material 12 C can dispose the welding line 13 B along which it is joined to the edge of the second web material 12 B in a position near the orthogonal line A-A orthogonal to the first reference line L 1 .
  • This makes it possible to increase the joint strength, that is, the welding strength in a position along the welding line 13 B between the second web material 12 B and the third web material 12 C to the stress that is produced in the left and right web plates 12 between the boss member 21 and the boss member 20 on the boom foot side by the expanding and contracting operation and the like of the boom cylinder 11 A and increase welding life and reliability.
  • the third web material 12 C can dispose the welding line 13 C along which it is joined to the edge of the fourth web material 12 D in a position near the orthogonal line B-B orthogonal to the second reference line L 2 .
  • This makes it possible to increase the joint strength, that is, the welding strength in a position along the welding line 13 C between the third web material 12 C and the fourth web material 12 D to the stress that is produced in the left and right web plates 12 between the boss member 21 and the bracket member 23 by the expanding and contracting operation of the arm cylinder 9 A, the expanding and contracting operation of the boom cylinder 11 A, and the like, and increase welding life and reliability.
  • the first partition plate 18 can be provided by being joined between the upper and lower flange plates 14 and 16 by welding, and the first partition plate 18 can increase the joint strength by welding between the left and right web plates 12 and the upper and lower flange plates 14 and 16 .
  • the second partition plate 19 can be provided by being joined between the upper and lower flange plates 14 and 16 by welding, and the second partition plate 19 can increase the joint strength by welding between the left and right web plates 12 and the upper and lower flange plates 14 and 16 .
  • the left and right web plates 12 and the upper and lower flange plates 14 and 16 can be formed by using a plate material with a requisite minimum plate thickness, which makes it possible to reduce the cost of material and reduce the weight of the boom 11 as a whole.
  • This makes it possible to form the boom cylinder 11 A as a smaller hydraulic cylinder.
  • it is possible to reduce the inertial force exerted when the boom 11 is moved upward and downward by the boom cylinder 11 A and improve the positioning performance and the like when the boom 11 is stopped in a desired position.
  • FIG. 10 shows a second embodiment of the present invention.
  • a feature of the second embodiment is that a left web plate and a right web plate are each formed of a total of six plate materials, an upper flange plate is formed of a total of four plate materials, and a lower flange plate is formed of a total of seven plate materials.
  • the component elements that are identical to those of the foregoing first embodiment will be simply denoted by the same reference numerals to avoid repetitions of similar explanations.
  • a boom adopted in the second embodiment, and the boom 41 is formed in substantially the same way as the boom 11 described in the first embodiment.
  • the boom 41 is formed of a pair of left and right web plates 42 and 42 extending in a length direction (a front-rear direction) thereof and facing each other in a left-right direction and upper and lower flange plates 43 and 44 joined to the upper and lower end sides of the web plates 42 by welding, respectively, and the boom 41 is formed as the box shape structural body being a closed section structure which is quadrangular in cross section.
  • the left and right web plates 42 differ from the first embodiment in that the left and right web plates 42 are each formed of a total of six plate materials. That is, the web plate 42 is formed of a total of six plate materials such as first to fourth web materials 42 A to 42 D which are formed in the same way as the first to fourth web materials 12 A to 12 D described in the first embodiment, a fifth web material 42 E, and a sixth web material 42 F.
  • the fifth web material 42 E and the sixth web material 42 F are formed by dividing the fifth web material 12 E described in the form of the above-mentioned first embodiment into two plate materials.
  • the fifth web material 42 E is joined, at the front end thereof, to a rear end side of the sixth web material 42 F along a welding line (not shown).
  • the first web material 42 A of the web plate 42 is bent in the position of a bending line 42 A 1 closer to the front side in such a way that the first web material 42 A is curved to the outside in a left-right direction.
  • both upper and lower end sides of the third web material 42 C are arc-shaped edge portions 42 C 1 and 42 C 2 , and, between the edge portions 42 C 1 and 42 C 2 , a circular punching hole 42 C 3 is formed to which an annular flange portion 21 B of a boss member 21 is joined by welding.
  • the upper flange plate 43 differs from the first embodiment in that the upper flange plate 43 is formed of a total of four plate materials. That is, the upper flange plate 43 is formed of a total of four plate materials, a first upper flange material 43 A located on the rear end side of the entire length of the upper flange plate 14 , a second upper flange material 43 B located in front of the first upper flange material 43 A, a third upper flange material 43 C located in front of the second upper flange material 43 B, and a fourth upper flange material 43 D located in front of the third upper flange material 43 C.
  • the first upper flange material 43 A is formed in the same way as the rear upper flange material 14 A described in the first embodiment
  • the second upper flange material 43 B is formed in the same way as the middle upper flange material 14 C described in the first embodiment
  • the third upper flange material 43 C and the fourth upper flange material 43 D are formed by dividing the front upper flange material 14 B described in the form of the above-mentioned first embodiment into two plate materials.
  • the front end of the third upper flange material 43 C is joined to the rear end of the fourth upper flange material 43 D along a welding line (not shown).
  • the lower flange plate 44 differs from the first embodiment in that the lower flange plate 44 is formed of a total of seven plate materials. That is, the lower flange plate 44 is formed of a total of seven plate materials, first to fourth lower flange materials 44 A to 44 D formed in the same way as the first to fourth lower flange materials 16 A to 16 D described in the first embodiment, a fifth lower flange material 44 E, a sixth lower flange material 44 F, and a seventh lower flange material 44 GE.
  • the fifth lower flange material 44 E and the sixth lower flange material 44 F of the lower flange plate 44 are formed by dividing the fifth lower flange material 16 E of the lower flange plate 16 described in the form of the above-mentioned first embodiment into two plate materials, and, in this respect, this embodiment differs from the form of the first embodiment.
  • the front end of the fifth lower flange material 44 E is joined to the rear end of the sixth lower flange material 44 F along a welding line (not shown).
  • the seventh lower flange material 44 G of the lower flange plate 44 is formed in the same way as the sixth lower flange material 16 F of the lower flange plate 16 described in the form of the above-mentioned first embodiment.
  • the end portions of the welding lines between the first to sixth web materials 42 A to 42 F forming the left and right web plates 42 and the end portions of the welding lines between the first to fourth upper flange materials 43 A to 43 D forming the upper flange plate 43 are disposed in positions that are different from one another in a front-rear direction. Furthermore, the end portions of the welding lines between the first to sixth web materials 42 A to 42 F forming the left and right web plates 42 and the end portions of the welding lines between the first to seventh lower flange materials 44 A to 44 G forming the lower flange plate 44 are disposed in positions that are different from one another in a front-rear direction.
  • the left and right web plates 42 and the upper and lower flange plates 43 and 44 can be formed by using a plate material with a requisite minimum plate thickness, making it possible to produce almost the same advantage as that in the first embodiment.
  • the left and right web plates 42 are each formed of six plate materials
  • the upper flange plate 43 is formed of four plate materials
  • the lower flange plate 44 is formed of seven plate materials.
  • the present invention is not limited to the same; for example, the left and right web plates may be each formed of seven plate materials, the upper flange plate may be formed of three plate materials, and the lower flange plate may be formed of six plate materials.
  • the left and right web plates may be each formed of five plate materials, the upper flange plate may be formed of four plate materials, for example, and the lower flange plate may be formed of six plate materials.
  • the left and right web plates are each formed of five plate materials
  • the upper flange plate is formed of four plate materials
  • the lower flange plate is formed of six plate materials. That is, according to the present invention, it is necessary simply to adopt a configuration in which the left and right web plates are each formed of at least five plate materials, the upper flange plate is formed of at least three plate materials, and the lower flange plate is formed of at least six plate materials.

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  • Mining & Mineral Resources (AREA)
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  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Butt Welding And Welding Of Specific Article (AREA)
  • Body Structure For Vehicles (AREA)
US13/994,821 2011-04-20 2011-04-20 Boom for construction machine Abandoned US20140056677A1 (en)

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US20130142607A1 (en) * 2011-09-20 2013-06-06 Steven J. Ditzler Boom apparatus with sandwiched knuckle body
US20140334906A1 (en) * 2012-02-16 2014-11-13 Hitachi Construction Machinery Co., Ltd. Arm for construction machine
US20150090850A1 (en) * 2012-02-14 2015-04-02 Cifa Spa Segment of an articulated arm and articulated arm comprising said segment
JP2016089375A (ja) * 2014-10-30 2016-05-23 日立建機株式会社 建設機械用ブーム
CN109537656A (zh) * 2018-11-26 2019-03-29 中联重科股份有限公司 动臂、动臂的制造方法以及挖掘机
US10370817B2 (en) * 2014-06-05 2019-08-06 Hitachi Construction Machinery Co., Ltd. Boom for construction machine
US10450717B1 (en) * 2019-04-12 2019-10-22 Deere & Company Attachment assembly for a work vehicle with reinforcement members

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JP6301754B2 (ja) * 2014-06-26 2018-03-28 株式会社神戸製鋼所 板材及びこれを備えた建設機械のアタッチメント並びにアタッチメントの製造方法
JP6305846B2 (ja) * 2014-06-26 2018-04-04 株式会社神戸製鋼所 アタッチメント構成部材及びこれを備えた建設機械のアタッチメント並びにアタッチメントの製造方法
JP6721432B2 (ja) * 2016-06-27 2020-07-15 株式会社小松製作所 油圧ショベルの作業機、および油圧ショベルの作業機の製造方法
US10072392B2 (en) * 2016-09-29 2018-09-11 Deere & Company Boom foot design with protruding flanges
JP6756567B2 (ja) * 2016-09-30 2020-09-16 株式会社小松製作所 作業機用の箱形構造体
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JPWO2012144037A1 (ja) 2014-07-28
WO2012144037A1 (ja) 2012-10-26
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EP2700752A1 (de) 2014-02-26
CN103403263B (zh) 2015-06-10
CN103403263A (zh) 2013-11-20

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