Work implement and work machine

Abstract

To suppress deterioration of durability of a working machine.SOLUTION: The work implement of the work machine includes a work implement element. The working machine element includes a first member having a pair of first connection surfaces in a cross section of the working machine element, and a second member having a pair of second connection surfaces welded to the pair of first connection surfaces, respectively. In the longitudinal direction of the implement element, the respective plate thicknesses of a plurality of portions of the implement element are different from each other.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a work implement and a work machine. [Background technology]

[0002] A work machine is equipped with a work implement including a boom and an arm. Patent Document 1 discloses a construction machine equipped with a boom. In Patent Document 1, the boom is equipped with a left web plate, a right web plate, an upper flange plate joined to the upper ends of the left and right web plates by welding, and an upper flange plate joined to the lower ends of the left and right web plates by welding. In Patent Document 1, the cross section of the boom is rectangular, and welds are formed at the four corners of the boom. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2012 / 144037 Summary of the Invention [Problem to be solved by the invention]

[0004] When a work machine performs work, stresses such as bending stress or torsional stress act on the work machine. If the welded parts are fatigued due to the action of stress, the durability of the work machine may be reduced.

[0005] The present disclosure aims to suppress a decrease in the durability of a work machine. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a work implement for a work machine. The work implement includes a work implement element. The work implement element has a first member having a pair of first connection surfaces in a cross section of the work implement element, and a second member having a pair of second connection surfaces welded to each of the pair of first connection surfaces. In the longitudinal direction of the work implement element, the plate thicknesses of multiple portions of the work implement element are different from each other. [Effects of the Invention]

[0007] According to the present disclosure, a decrease in the durability of the work machine is suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a work machine according to an embodiment. [Figure 2] FIG. 2 is a side view showing a boom according to the embodiment. [Figure 3] FIG. 3 is a vertical cross-sectional view showing a boom according to the embodiment. [Figure 4] FIG. 4 is a perspective cross-sectional view showing a boom according to the embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing a boom according to the embodiment. [Figure 6] FIG. 6 is a plan view schematically showing the boom according to the embodiment. [Figure 7] FIG. 7 is a diagram for explaining the shape of the boom according to the embodiment. [Figure 8] FIG. 8 is a perspective cross-sectional view showing a boom according to a modified example of the embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a boom according to a modified example of the embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a boom according to a modified example of the embodiment. [Figure 11] FIG. 11 is a side view showing the arm according to the embodiment. [Figure 12] FIG. 12 is a vertical cross-sectional view showing the arm according to the embodiment. [Figure 13]FIG. 13 is a plan view schematically showing the arm according to the embodiment. [Figure 14] FIG. 14 is a diagram for explaining the shape of the arm according to the embodiment. [Figure 15] FIG. 15 is a diagram schematically illustrating an example of a connection structure between a first connection surface and a second connection surface according to the embodiment. [Figure 16] FIG. 16 is a diagram schematically illustrating an example of a connection structure between a first connection surface and a second connection surface according to the embodiment. [Figure 17] FIG. 17 is a diagram schematically illustrating an example of a connection structure between a first connection surface and a second connection surface according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited thereto. The components of each embodiment described below can be combined as appropriate. In addition, some components may not be used.

[0010] [First embodiment] A first embodiment will be described.

[0011] <Work machinery> Fig. 1 is a perspective view showing a work machine 1 according to an embodiment. In the embodiment, the work machine 1 is a hydraulic excavator. As shown in Fig. 1, the work machine 1 includes a traveling body 2, a rotating body 3, a work implement 4, and a hydraulic cylinder 5.

[0012] The running body 2 runs on the work site. The running body 2 supports a rotating body 3. The running body 2 has a pair of tracks 2A. The work machine 1 runs by rotation of the tracks 2A. The rotating body 3 is supported on the running body 2 so as to be able to rotate. The rotating body 3 rotates around a rotation axis RX.

[0013] The work implement 4 is supported by the rotating unit 3. The work implement 4 has a plurality of work implement elements 6 that are rotatable relative to one another. The work implement elements 6 of the work implement 4 include a boom 61 connected to the rotating unit 3, an arm 62 connected to the boom 61, and a bucket 63 connected to the arm 62.

[0014] The boom 61 is connected to the rotating body 3 so as to be rotatable about a rotation axis AX1. The arm 62 is supported by the boom 61 so as to be rotatable about a rotation axis AX2. The bucket 63 is supported by the arm 62 so as to be rotatable about a rotation axis AX3.

[0015] The rotation axes AX1, AX2, and AX3 are parallel to each other. The rotation axis AX1 and an axis parallel to the rotation axis RX are perpendicular to each other. In the following description, the direction parallel to the rotation axis RX will be referred to as the up-down direction of the rotating unit 3, the direction parallel to the rotation axis AX1 will be referred to as the width direction or left-right direction of the rotating unit 3, and the direction perpendicular to both the rotation axis AX1 and the rotation axis RX will be referred to as the fore-and-aft direction of the rotating unit 3. The direction in which the work implement 4 is located relative to the rotation axis RX is the front. The work implement element 6 rotates around rotation axes (AX1, AX2, AX3) extending in the left-right direction.

[0016] The hydraulic cylinders 5 operate the work equipment elements 6 based on hydraulic oil. A plurality of hydraulic cylinders 5 are provided to operate each of the plurality of work equipment elements 6. The hydraulic cylinders 5 include a boom cylinder 7 for operating the boom 61, an arm cylinder 8 for operating the arm 62, and a bucket cylinder 9 for operating the bucket 63.

[0017] The cylinder tube of the boom cylinder 7 is connected to the rotating body 3. The rod of the boom cylinder 7 is connected to the boom 61. The cylinder tube of the arm cylinder 8 is connected to the boom 61. The rod of the arm cylinder 8 is connected to the arm 62. The cylinder tube of the bucket cylinder 9 is connected to the arm 62. The rod of the bucket cylinder 9 is connected to the bucket 63.

[0018] <boom> FIG. 2 is a side view showing a boom 61 according to the embodiment. FIG. 3 is a longitudinal cross-sectional view showing the boom 61 according to the embodiment. FIG. 4 is a perspective cross-sectional view showing the boom 61 according to the embodiment. The boom 61 has a base end bracket 10 connected to the revolving unit 3, a tip end bracket 11 connected to the arm 62, a cylinder boss 12 to which the rod of the boom cylinder 7 is connected, and a cylinder bracket 13 to which the cylinder tube of the arm cylinder 8 is connected. The cylinder bosses 12 are provided on each of the left and right outer surfaces of the boom 61. A bending portion 14 is provided in the central portion of the boom 61 in the longitudinal direction of the boom 61. In the example shown in FIG. 2, the boom 61 has a base end portion extending upward and forward from the base end bracket 10 and a tip end portion where the bending portion 14 is connected to the base end portion. The tip end portion extends forward from the bending portion 14. The cylinder bosses 12 are provided on each of the left and right outer surfaces of the bending portion 14.

[0019] The boom 61 has a first member 21 arranged on one side of the neutral axis BX in a cross section of the boom 61, and a second member 22 arranged on the other side of the neutral axis BX.

[0020] The neutral axis BX refers to an axis passing through the center of gravity of the cross section of the boom 61. The neutral axis BX is an axis on which tensile force and compressive force are substantially balanced when a bending moment acts on the boom 61. The neutral axis BX may be considered to be the central axis or centroid axis of the boom 61. The longitudinal direction of the boom 61 is the direction along the neutral axis BX.

[0021] In the embodiment, the first member 21 is disposed on the left side of the neutral axis BX. The second member 22 is disposed on the right side of the neutral axis BX. That is, the first member 21 and the second member 22 are disposed in the left-right direction. The first member 21 is disposed on the left side of the second member 22.

[0022] Figure 5 is a cross-sectional view showing a boom 61 according to an embodiment. The cross-section of the boom 61 refers to a cross-section perpendicular to the neutral axis BX. Figure 5 corresponds to the cross-sectional view taken along line BB in Figure 2. In the following description, the direction parallel to the pivot axis AX1 in the cross-section perpendicular to the neutral axis BX will be referred to as the horizontal direction as appropriate, and the direction perpendicular to the horizontal direction in the cross-section perpendicular to the neutral axis BX will be referred to as the vertical direction as appropriate.

[0023] The boom 61 has a first member 21 and a second member 22 arranged on the right side of the first member 21. The first member 21 and the second member 22 are each plate-shaped. The first member 21 has a pair of first connecting surfaces 23. The second member 22 has a pair of second connecting surfaces 24. The first connecting surface 23 is an end surface of the first member 21. The second connecting surface 24 is an end surface of the second member 22. The pair of first connecting surfaces 23 are arranged in the vertical direction. The pair of second connecting surfaces 24 are arranged in the vertical direction. The upper first connecting surface 23 and the upper second connecting surface 24 face each other. The lower first connecting surface 23 and the lower second connecting surface 24 face each other. The pair of second connecting surfaces 24 are welded to each of the pair of first connecting surfaces 23.

[0024] In the example shown in FIG. 5, a groove portion and a butt portion are formed at the boundary between the first member 21 and the second member 22. The first connection surface 23 includes a region 231 of the groove portion and a region 232 of the butt portion. The second connection surface 24 includes a region 241 of the groove portion and a region 242 of the butt portion. In the example shown in FIG. 5, the regions 231 and 241 of the groove portion are melted and welded using a welding material (welding rod). The regions 232 and 242 of the butt portion face each other. Alternatively, the regions 232 and 242 may be melted and welded using a welding material.

[0025] The first member 21 has a pair of first connection portions 211 including first connection surfaces 23 in a cross section, and first intermediate portions 212 connected to each of the pair of first connection portions 211 via first bent portions 213. In the cross section, the first intermediate portions 212 are long in the vertical direction. The upper first connection portion 211 is connected to an upper end portion of the first intermediate portion 212 via the upper first bent portion 213. The upper first connection portion 211 extends rightward from the upper first bent portion 213. The lower first connection portion 211 is connected to a lower end portion of the first intermediate portion 212 via the lower first bent portion 213. The lower first connection portion 211 extends rightward from the lower first bent portion 213.

[0026] The second member 22 has a pair of second connection portions 221 including the second connection surface 24 in a cross section, and second intermediate portions 222 connected to each of the pair of second connection portions 221 via second bent portions 223. In the cross section, the second intermediate portions 222 are long in the vertical direction. The upper second connection portion 221 is connected to an upper end portion of the second intermediate portion 222 via the upper second bent portion 223. The upper second connection portion 221 extends leftward from the upper second bent portion 223. The lower second connection portion 221 is connected to a lower end portion of the second intermediate portion 222 via the lower second bent portion 223. The lower second connection portion 221 extends leftward from the lower second bent portion 223.

[0027] In the cross section, the first member 21 and the second member 22 are line-symmetrical with respect to an axis that passes through the neutral axis BX and extends in the vertical direction. In the cross section, the thickness of the first member 21 is substantially uniform, and the thickness of the second member 22 is substantially uniform. The radii of curvature of the pair of first bending portions 213 are the same as each other. The radii of curvature of the pair of second bending portions 223 are the same as each other. The radii of curvature of the first bending portion 213 and the second bending portion 223 are the same as each other. In the cross section, the vertical dimension of the boom 61 is greater than the lateral dimension.

[0028] The pair of second connecting surfaces 24 are welded to the pair of first connecting surfaces 23, respectively. In the embodiment, the first connecting surfaces 23 and the second connecting surfaces 24 are butt-welded. By welding the first connecting surfaces 23 and the second connecting surfaces 24, a weld 25 is formed at the boundary between the first connecting surfaces 23 and the second connecting surfaces 24. The weld 25 includes a weld bead. In the embodiment, the weld 25 is formed in the groove portion at the boundary between the first member 21 and the second member 22. Examples of a method for welding the first connecting surfaces 23 and the second connecting surfaces 24 include electric resistance welding and induction heating welding.

[0029] The hollow boom 61 is formed by welding the first connection surface 23 and the second connection surface 24. The boom 61 is disposed so as to surround the neutral axis BX.

[0030] The inner surface of the boom 61 includes a left inner surface 26 disposed on the left side of the neutral axis BX, a right inner surface 27 disposed on the right side of the neutral axis BX, a top surface 28 disposed above the neutral axis BX, and a bottom surface 29 disposed below the neutral axis BX. The left inner surface 26 faces to the right. The right inner surface 27 faces to the left. The top surface 28 faces downward. The bottom surface 29 faces upward. The left inner surface 26 includes the right surface of the first intermediate portion 212 facing to the right. The right inner surface 27 includes the left surface of the second intermediate portion 222 facing to the left. The top surface 28 includes the lower surfaces of the first connecting portion 211 and the second connecting portion 221 disposed above the neutral axis BX and facing downward. The bottom surface 29 includes the upper surfaces of the first connecting portion 211 and the second connecting portion 221 disposed below the neutral axis BX and facing upward.

[0031] The outer surfaces of the boom 61 include a left outer surface 31 disposed on the left side of the neutral axis BX, a right outer surface 32 disposed on the right side of the neutral axis BX, an upper surface 33 disposed above the neutral axis BX, and a lower surface 34 disposed below the neutral axis BX. The left outer surface 31 faces left. The right outer surface 32 faces right. The upper surface 33 faces upward. The lower surface 34 faces downward. The left outer surface 31 includes the left surface of the first intermediate portion 212 facing left. The right outer surface 32 includes the right surface of the second intermediate portion 222 facing right. The upper surface 33 includes the upper surfaces of the first connecting portion 211 and the second connecting portion 221 disposed above the neutral axis BX and facing upward. The lower surface 34 includes the lower surface of the first connection portion 211 and the lower surface of the second connection portion 221, which are disposed below the neutral axis BX and face downward.

[0032] The first connection surface 23 and the second connection surface 24 are butt-welded so that the lower surface of the first connection portion 211 connected to the first connection surface 23 above the neutral axis BX and the lower surface of the second connection portion 221 connected to the second connection surface 24 are arranged in the same plane. In other words, the top surface 28 is substantially flat.

[0033] The first connection surface 23 and the second connection surface 24 are butt-welded so that the upper surface of the first connection portion 211 connected to the first connection surface 23 above the neutral axis BX and the upper surface of the second connection portion 221 connected to the second connection surface 24 are arranged in the same plane. In other words, the upper surface 33 is substantially flat.

[0034] The first connection surface 23 and the second connection surface 24 are butt-welded so that the upper surface of the first connection portion 211 connected to the first connection surface 23 below the neutral axis BX and the upper surface of the second connection portion 221 connected to the second connection surface 24 are arranged in the same plane. In other words, the bottom surface 29 is substantially flat.

[0035] The first connection surface 23 and the second connection surface 24 are butt-welded so that the lower surface of the first connection portion 211 connected to the first connection surface 23 below the neutral axis BX and the lower surface of the second connection portion 221 connected to the second connection surface 24 are arranged in the same plane. In other words, the lower surface 34 is substantially flat.

[0036] The left inner surface 26 and the right inner surface 27 face each other with a gap therebetween. The left inner surface 26 and the right inner surface 27 are substantially parallel. The top surface 28 and the bottom surface 29 face each other with a gap therebetween. The top surface 28 and the bottom surface 29 are substantially parallel.

[0037] 6 is a plan view schematically showing a boom 61 according to an embodiment. In the longitudinal direction of the boom 61, the distance G between the left inner surface 26 and the right inner surface 27 is constant. At the bent portion 14, which is the center in the longitudinal direction, the left outer surface 31 bulges leftward, and the right outer surface 32 bulges rightward.

[0038] 3 and 6, the thicknesses of the multiple portions of the boom 61 differ from one another in the longitudinal direction of the boom 61. The thickness of the boom 61 includes a thickness th of the first connecting portion 211 or the second connecting portion 221 and a thickness ts of the first intermediate portion 212 or the second intermediate portion 222. The thickness th is the distance between the top surface 28 and the upper surface 33, or the distance between the bottom surface 29 and the lower surface 34, in the cross section. The thickness ts is the distance between the left inner surface 26 and the left outer surface 31, or the distance between the right inner surface 27 and the right outer surface 32, in the cross section.

[0039] As shown in Fig. 3, in the longitudinal direction of the boom 61, the plate thickness th is the thickest at the bending portion 14 which is the center of the boom 61, and the plate thickness th becomes thinner toward the end of the boom 61. As shown in Fig. 6, in the longitudinal direction of the boom 61, the plate thickness ts is the thickest at the bending portion 14 which is the center of the boom 61, and the plate thickness ts becomes thinner toward the end of the boom 61. In other words, each of the plate thickness th and the plate thickness ts becomes gradually thinner from the center of the boom 61 toward the rear end (base end), and gradually thinner from the center of the boom 61 toward the front end (tip end).

[0040] Fig. 7 is a diagram for explaining the shape of the boom 61 according to the embodiment. Fig. 7 shows a cross-sectional view taken along the line AA, the line BB, and the line CC in Fig. 2. As shown in Fig. 7, the vertical dimension of the boom 61 is greater than the horizontal dimension at each of the rear end (base end), the central portion, and the front end (tip end) of the boom 61.

[0041] 7, in the longitudinal direction of the boom 61, the plate thickness th at the central portion is thicker than the plate thickness th at the rear end (base end) and the plate thickness th at the front end (tip end). In the longitudinal direction of the boom 61, the plate thickness ts at the central portion is thicker than the plate thickness ts at the rear end (base end) and the plate thickness ts at the front end (tip end).

[0042] Furthermore, in the longitudinal direction of the boom 61, the vertical dimension H of each of the multiple portions of the boom 61 differs from one another. In the longitudinal direction of the boom 61, the dimension H of the bent portion 14, which is the central portion of the boom 61, is the largest, and the dimension H decreases toward the ends of the boom 61. In the longitudinal direction of the boom 61, the dimension H at the central portion is larger than the dimension H of the rear end (base end) and the dimension H of the front end (tip end). The dimension H gradually decreases from the central portion of the boom 61 toward the rear end (base end), and gradually decreases from the central portion of the boom 61 toward the front end (tip end).

[0043] The boom 61 has a plurality of bending portions (213, 223) that are bent in cross section. The radius of curvature R of the first bending portion 213 and the radius of curvature R of the second bending portion 223 are the same. In the longitudinal direction of the boom 61, the radius of curvature R of each bending portion of the plurality of portions of the boom 61 differs from one another. In the longitudinal direction of the boom 61, the radius of curvature R of the bending portion 14 at the center of the boom 61 is largest, and the radius of curvature R decreases toward the ends of the boom 61. In the longitudinal direction of the boom 61, the radius of curvature R at the center is larger than the radius of curvature R at the rear end (base end) and the radius of curvature R at the front end (tip end). The radius of curvature R gradually decreases from the center of the boom 61 toward the rear end (base end) and from the center of the boom 61 toward the front end (tip end). That is, in the longitudinal direction of the boom 61, the cross-sectional shape at the center of the boom 61 is close to an ellipse, and the cross-sectional shape becomes closer to a rectangle towards the ends of the boom 61.

[0044] As described with reference to Figure 6, the distance G between the left inner surface 26 and the right inner surface 27 is constant in the longitudinal direction of the boom 61. The plate thickness ts varies based on the amount of leftward bulging of the left outer surface 31 and the amount of rightward bulging of the right outer surface 32.

[0045] In this embodiment, the boom 61 is made of high-tensile steel. 2 In the embodiment, the high-tensile steel material has a tensile strength of 490 N / mm when measured by the metallic material tensile test method according to "JIS Z 2241". 2 The above steel materials are used.

[0046] <Effects> As described above, according to the embodiment, the boom 61 includes the first member 21, which is disposed on the left side of the neutral axis BX in a cross section and has a pair of first connection surfaces 23, and the second member 22, which is disposed on the right side of the neutral axis BX and has a pair of second connection surfaces 24 welded to each of the pair of first connection surfaces 23. In the longitudinal direction of the boom 61 along the neutral axis BX, the plate thicknesses th and ts of the multiple portions of the boom 61 are different from one another. In the embodiment, the plate thicknesses th and ts are thickest at the center in the longitudinal direction and become thinner toward the ends of the boom 61.

[0047] According to the embodiment, a decrease in durability of the boom 61 is suppressed. When the work implement 4 is working, the load acting on the center portion of the boom 61 is greater than the load acting on the end portion of the boom 61. That is, the greatest stress acts on the center portion of the boom 61. Because the plate thicknesses th and ts at the center portion are the thickest, a decrease in strength at the center portion is suppressed. The stress acting on the end portion of the boom 61 is smaller than the stress acting on the center portion. Because the plate thicknesses th and ts at the end portions are thin, the weight of the boom 61 is reduced. The weight reduction of the boom 61 improves the fuel efficiency of the work machine 1. Furthermore, the weight reduction of the boom 61 increases the amount of work performed by the work implement 4, including the amount of material excavated and transported.

[0048] Furthermore, the boom 61 is formed by welding the first member 21 and the second member 22 together. When the work implement 4 performs work, stresses such as bending stress or torsional stress act on the work implement 4. In the cross section of the boom 61, large stresses act on the four corners of the boom 61. In this embodiment, there are no welded portions 25 at the four corners of the boom 61, but there are bent portions (213, 223). Because there are no welded portions 25 in the areas where stress is concentrated, fatigue of the welded portions 25 due to stress is suppressed. As a result, a decrease in the durability of the boom 61 is suppressed.

[0049] The radii of curvature R of the bent portions (213, 223) of the multiple portions of the boom 61 differ from one another in the longitudinal direction of the boom 61. In the embodiment, the radii of curvature R are greatest at the center portion in the longitudinal direction, and become smaller toward the ends of the boom 61.

[0050] Since the radius of curvature R is large in the central portion where large stress acts, stress concentration at the bent portions (213, 223) is suppressed. Since the radius of curvature R is small at the ends, the section modulus at the ends is large. Since the section modulus at the ends is large, buckling is less likely to occur. A decrease in durability of the boom 61 is suppressed. In addition, a base end bracket 10 is provided at the base end of the boom 61, and a tip bracket 11 is provided at the tip end of the boom 61. Since the cross-sectional shape at the ends is similar to the cross-sectional shape of existing booms, the existing base end bracket 10 and tip bracket 11 can be attached to the boom 61.

[0051] In the longitudinal direction of the boom 61, the vertical dimension H is greatest at the center, and the vertical dimension H decreases toward the ends of the boom 61.

[0052] Since the cross-sectional area of ​​the central portion where large stress acts is large, a decrease in strength at the central portion is suppressed. Since the dimension H of the end portion is small, the weight of the boom 61 can be reduced.

[0053] In the embodiment, the boom 61 is made of high-tensile steel. In the embodiment, fatigue of the welded portion 25 is suppressed, and therefore, by forming the boom 61 from high-tensile steel, both improved durability and weight reduction of the boom 61 are achieved.

[0054] <Modification> Modified examples of the boom 61 will be described below. FIG. 8 is a perspective cross-sectional view showing a boom 611 according to a modified example of the embodiment. In the above-described embodiment, the boom 611 is manufactured by combining the first member 21 and the second member 22 disposed on the right side of the first member 21. The boom 611 may also be manufactured by combining multiple members disposed in the longitudinal direction. In the example shown in FIG. 8, the boom 611 includes a first portion 61A, a second portion 61B disposed adjacent to the first portion 61A in the longitudinal direction, and a third portion 61C disposed adjacent to the second portion 61B in the longitudinal direction. The second portion 61B is disposed rearward of the first portion 61A. The third portion 61C is disposed rearward of the second portion 61B. The rear end of the first portion 61A and the front end of the second portion 61B are welded together. The rear end of the second portion 61B and the front end of the third portion 61C are welded together. A welded portion 35 is formed at the boundary between the rear end of the first portion 61A and the front end of the second portion 61B. A welded portion 35 is formed at the boundary between the rear end of the second portion 61B and the front end of the third portion 61C.

[0055] FIG. 9 is a cross-sectional view showing a boom 612 according to a modified example of the embodiment. As shown in FIG. 9, the boom 612 includes a first member 21C having a pair of first connection surfaces 23C and a second member 22C having a pair of second connection surfaces 24C welded to the pair of first connection surfaces 23C, respectively. The first connection surfaces 23C include a groove region 231C and a butt region 232C. The second connection surfaces 24C include a groove region 241C and a butt region 242C. The first member 21C has a pair of first connection portions 211C including the first connection surfaces 23C. The second member 22C has a pair of second connection portions 221C including the second connection surfaces 24C. The first connection surfaces 23C and the second connection surfaces 24C are welded. A weld 25C is formed at the boundary between the region 231C of the first connection surfaces 23C and the region 241C of the second connection surfaces 24C. In cross section, the thickness th of the first connecting portion 211C increases toward the first connecting surface 23C, and the thickness th of the second connecting portion 221C increases toward the second connecting surface 24C. Because the areas of the first connecting surface 23C (region 231C) and the second connecting surface 24C (region 241C) are each large, welding between the first connecting surface 23C and the second connecting surface 24C is carried out smoothly, and a decrease in welding strength is suppressed.

[0056] FIG. 10 is a cross-sectional view showing a boom 613 according to a modified example of the embodiment. As shown in FIG. 10, a first member 21D and a second member 22D may be arranged in a vertical direction. In the example shown in FIG. 10, the first member 21D is arranged above the second member 22D. A first connecting surface 23D of the first member 21D and a second connecting surface 24D of the second member 22D are welded together. The first connecting surface 23D includes a region 231D of the groove portion and a region 232D of the butt portion. The second connecting surface 24D includes a region 241D of the groove portion and a region 242D of the butt portion. A weld 25D is formed at the boundary between the region 231D of the first connecting surface 23D and the region 241D of the second connecting surface 24D.

[0057] [Second embodiment] Next, a second embodiment will be described. In the following description, components that are the same as or equivalent to those in the above-described embodiment will be given the same reference numerals, and descriptions of those components will be simplified or omitted. In the second embodiment, the arm 62 will be described.

[0058] Fig. 11 is a side view showing the arm 62 according to the embodiment. Fig. 12 is a longitudinal sectional view showing the arm 62 according to the embodiment. Fig. 13 is a plan view schematically showing the arm 62 according to the embodiment. Fig. 14 is a diagram for explaining the shape of the arm 62 according to the embodiment. Fig. 14 shows a cross-sectional view taken along the line DD and a cross-sectional view taken along the line EE in Fig. 11.

[0059] 11, the arm 62 has a boom boss 15 to which the tip of the boom 61 is connected, a bucket boss 16 to which the bucket 63 is connected, a cylinder bracket 17 to which the rod of the arm cylinder 8 is connected, and a cylinder bracket 18 to which the cylinder tube of the bucket cylinder 9 is connected. The boom boss 15 is a connection part provided at the base end (one end) of the arm 62 to connect with the boom 61. The bucket boss 16 is a connection part provided at the tip end (other end) of the arm 62 to connect with the bucket 63.

[0060] 12, 13, and 14, the arm 62 has a first member 41 disposed on the left side of the neutral axis BX of the arm 62, and a second member 42 disposed on the right side of the neutral axis BX. The first member 41 has a pair of first connecting surfaces 43. The second member 42 has a pair of second connecting surfaces 44 welded to the pair of first connecting surfaces 43, respectively. A weld 45 is formed at the boundary between the first connecting surface 43 and the second connecting surface 44.

[0061] In the arm 62, the plate thickness th is greatest at the base end of the arm 62 in the longitudinal direction of the arm 62, and the plate thickness th becomes thinner toward the tip end of the arm 62. In addition, the plate thickness ts of the arm 62 is greatest at the base end of the arm 62, and the plate thickness ts becomes thinner toward the tip end of the arm 62.

[0062] As shown in Figure 13, the inner surface of the arm 62 includes a left inner surface 46 facing right and a right inner surface 47 facing left. The outer surface of the arm 62 includes a left outer surface 51 facing left and a right outer surface 52 facing right. In the longitudinal direction of the arm 62, a distance G between the left inner surface 46 and the right inner surface 47 is constant. In the longitudinal direction of the arm 62, a first portion 62A from the base end of the arm 62 where the cylinder bracket 17 is provided to the tip end of the cylinder bracket 18 has a constant plate thickness ts. In a second portion 62B from the tip end of the cylinder bracket 18 to the tip end of the arm 62 where the bucket boss 16 is provided, the plate thickness ts gradually becomes thinner toward the tip end of the arm 62.

[0063] In addition, in the longitudinal direction of the arm 62, the vertical dimension H of the base end of the arm 62 is the largest, and the vertical dimension H decreases toward the tip end of the arm 62.

[0064] In addition, in the longitudinal direction of the arm 62, the radius of curvature R of the bent portion at the base end of the arm 62 is the largest, and the radius of curvature R of the bent portion decreases toward the tip end of the arm 62.

[0065] The arm 62 is also prevented from decreasing in durability and is made lighter. Reducing the weight of the arm 62 improves the fuel efficiency of the work machine 1. In this embodiment, the plate thickness ts of the first portion 62A is constant. The first portion 62A includes the boom boss 15, which is a connection portion with the boom 61, the cylinder bracket 17, which is a connection portion with the boom cylinder 7, and the cylinder bracket 18, which is a connection portion with the bucket cylinder 9, and is likely to be subjected to high stress. Because the plate thickness ts of the first portion 62A is constant, the decrease in durability of the arm 62 is suppressed. Furthermore, reducing the weight of the arm 62 increases the amount of work that can be done by the work implement 4, including the amount of material excavated and transported.

[0066] [Other embodiments] 15, 16, and 17 are diagrams each schematically illustrating an example of a connection structure between the first connecting surface 23 and the second connecting surface 24 according to the embodiment. In the above-described embodiment, the first connecting surface 23 (first connecting surface 43) and the second connecting surface 24 (second connecting surface 44) are butt-welded. A groove is formed at a portion of the boundary between the first member 21 (first member 41) and the second member 22 (second member 42), and the first connecting surface 23 and the second connecting surface 24 are welded by melting the groove. A portion of the first connecting surface 23 may be welded to the second connecting surface 24, or the entire first connecting surface 23 may be welded to the second connecting surface 24. A portion of the second connecting surface 24 may be welded to the first connecting surface 23, or the entire second connecting surface 24 may be welded to the first connecting surface 23. As shown in Fig. 15, a groove may be formed on almost the entire boundary between the first member 21 and the second member 22, and the entire first connecting surface 23 and the entire second connecting surface 24 may be melted and welded together. As shown in Fig. 16, the first connecting surface 23 may include a protrusion 23T, and the second connecting surface 24 may include a protrusion 24T. That is, two grooves may be formed on one boundary between the first member 21 and the second member 22. As shown in Fig. 17, the first connecting surface 23 and the second connecting surface 24 may be welded together without forming a groove on the boundary between the first member 21 and the second member 22.

[0067] In the above-described embodiment, the first connecting surface 23 (first connecting surface 43) and the second connecting surface 24 (second connecting surface 44) are welded using a welding material (welding rod). The first connecting surface 23 (first connecting surface 43) and the second connecting surface 24 (second connecting surface 44) may be welded without using a welding material (welding rod). Examples of welding methods for welding the first connecting surface 23 and the second connecting surface 24 without using a welding material include electric resistance welding and induction heating welding. By electric resistance welding, induction heating welding, or the like, a portion of the first member 21 (first member 41) and a portion of the second member 22 (second member 42), which are base materials, are melted, thereby welding the first connecting surface 23 (first connecting surface 43) and the second connecting surface 24 (second connecting surface 44). [Explanation of symbols]

[0068] 1...working machine, 2...traveling body, 2A...track, 3...swivel body, 4...working machine, 5...hydraulic cylinder, 6...working machine element, 7...boom cylinder, 8...arm cylinder, 9...bucket cylinder, 10...base end bracket, 11...tip bracket, 12...cylinder boss, 13...cylinder bracket, 14...bending portion, 15...boom boss, 16...bucket boss, 17...cylinder bracket, 18...cylinder bracket, 21...first member, 21 C...first member, 21D...first member, 22...second member, 22C...second member, 22D...second member, 23...first connecting surface, 23C...first connecting surface, 23D...first connecting surface, 23T...projection, 24...second connecting surface, 24C...second connecting surface, 24D...second connecting surface, 24T...projection, 25...welded portion, 25C...welded portion, 25D...welded portion, 26...left inner surface, 27...right inner surface, 28...top surface, 29...bottom surface, 31...left outer surface, 32...right outer surface, 33...upper surface, 34...lower surface , 35...welded portion, 41...first member, 42...second member, 43...first connecting surface, 44...second connecting surface, 45...welded portion, 46...left inner surface, 47...right inner surface, 51...left outer surface, 52...right outer surface, 61...boom, 61A...first portion, 61B...second portion, 61C...third portion, 62...arm, 62A...first portion, 62B...second portion, 63...bucket, 211...first connecting portion, 211C...first connecting portion, 212...first intermediate portion, 213...first bent portion, 221...second 2 connection portion, 221C...second connection portion, 222...second intermediate portion, 223...second bending portion, 231...area, 231C...area, 231D...area, 232...area, 232C...area, 232D...area, 241...area, 241C...area, 241D...area, 242...area, 242C...area, 242D...area, 611...boom, 612...boom, 613...boom, AX1...rotating axis, AX2...rotating axis, AX3...rotating axis, BX...neutral axis, RX...swivel axis.

Claims

1. A work implement of a work machine, A work implement element is provided, The work machine element is a first member having a pair of first connection surfaces in a cross section of the work implement element; a second member having a pair of second connection surfaces welded to the pair of first connection surfaces, In the longitudinal direction of the work equipment element, the plate thicknesses of the plurality of portions of the work equipment element are different from each other, Work equipment.

2. the work implement element is a boom, a bent portion is provided in a central portion of the boom in the longitudinal direction, The plate thickness is the thickest in the central portion and becomes thinner toward the end portion of the boom. The work machine according to claim 1 .

3. the work implement element is an arm connected to a boom, a connecting portion for connecting to the boom is provided at one end of the arm in the longitudinal direction, The plate thickness is the thickest at the one end and becomes thinner toward the other end of the arm. The work machine according to claim 1 .

4. The work machine element has a bent portion that bends in the cross section, In the longitudinal direction, the radius of curvature of the bent portion of each of the plurality of portions of the work machine element is different from each other. The work machine according to claim 1 .

5. A work implement of a work machine, A work implement element is provided, The work machine element is The work implement element has a bent portion that is bent in cross section, In the longitudinal direction of the work machine element, the curvature radii of the bent portions of the plurality of portions of the work machine element are different from each other. Work equipment.

6. the work implement element is a boom, a bent portion is provided in a central portion of the boom in the longitudinal direction, The radius of curvature is largest at the center portion and decreases toward the end portion of the boom. The work machine according to claim 5.

7. The work machine element is a first member having a pair of first connecting surfaces in the cross section; a second member having a pair of second connection surfaces welded to the pair of first connection surfaces, The work machine according to claim 5.

8. The first connection surface and the second connection surface are welded together so that a surface of the first member connected to the first connection surface and a surface of the second member connected to the second connection surface are arranged in the same plane. A work machine according to claim 1 or claim 7.

9. the first member has a pair of first connection portions that include the first connection surface in the cross section, and a first intermediate portion that is connected to each of the pair of first connection portions via a first bent portion, The second member has a pair of second connection portions including the second connection surface in the cross section, and second intermediate portions connected to each of the pair of second connection portions via second bent portions. A work machine according to claim 1 or claim 8.

10. The work machine element rotates about a rotation axis extending in the left-right direction, The first member is disposed to the left of the second member. The work machine according to claim 9.

11. In the cross section, the plate thickness of the first connection portion increases toward the first connection surface, and the plate thickness of the second connection portion increases toward the second connection surface. The work machine according to claim 9.

12. A work implement of a work machine, A work implement element is provided, The work machine element is a first member having a pair of first connection surfaces and a pair of first connection portions including the first connection surfaces in a cross section of the work machine element; a second member having a pair of second connection surfaces welded to the pair of first connection surfaces, respectively, and a pair of second connection portions including the second connection surfaces; In the cross section, the plate thickness of the first connection portion increases toward the first connection surface, and the plate thickness of the second connection portion increases toward the second connection surface. Work equipment.

13. The work machine element rotates about a rotation axis extending in the left-right direction, In the cross section, the inner surface of the work machine element includes a left inner surface and a right inner surface opposite to the left inner surface, A distance between the left inner surface and the right inner surface is constant in the longitudinal direction. A work machine according to claim 1 or claim 8.

14. The work implement element rotates about a rotation axis extending in a lateral direction, In the cross section, the longitudinal dimension of the implement element is greater than the lateral dimension; A work machine according to claim 1 or claim 8.

15. The work implement element rotates about a rotation axis extending in a lateral direction, In the longitudinal direction, the vertical dimensions of the plurality of portions of the work machine element are different from each other; A work machine according to claim 1 or claim 8.

16. the work implement element is a boom, a bent portion is provided in a central portion of the boom in the longitudinal direction, the vertical dimension is greatest at the central portion and decreases toward the ends of the boom; 16. A work machine according to claim 15.

17. The work machine element is a first portion and a second portion disposed adjacent to the first portion in the longitudinal direction and welded to the first portion, A work machine according to claim 1 or claim 8.

18. The work machine element is made of high-tensile steel. A work machine according to claim 1 or claim 8.

19. A work machine comprising the work machine according to claim 1. Work machinery.

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