WO2021215208A1

WO2021215208A1 - Weld structure

Info

Publication number: WO2021215208A1
Application number: PCT/JP2021/013802
Authority: WO
Inventors: 博青山; 剛志井上
Original assignee: 株式会社日立製作所
Priority date: 2020-04-21
Filing date: 2021-03-31
Publication date: 2021-10-28
Also published as: JP7375175B2; JPWO2021215208A1

Abstract

Provided is a weld structure that reduces stress or strain of a weld in which a non-welded section exists, and that can improve the fatigue life of the weld while maintaining strength and rigidity. In this weld structure, two plates (1, 3) are secured to each other by fillet welding in which an end face of one of the plates (1) abuts against a surface of the other of the plates (3), wherein: there exists a non-welded section (8), which is a portion not welded, found between the end face of the one plate (1) and the surface of the other plate (3); and a groove (10) is formed in the one plate (1), the groove extending along the non-welded section (8), from a side face (12) that is on the side opposite from where the weld metal (5) of the fillet weld is present.

Description

Welded structure

The present invention relates to a welded structure, and more particularly to a welded structure suitable for welding metal plates to each other.

The structure in which steel plates are fixed to each other by welding is widely used in general machines. An example is a hydraulic excavator. The hydraulic excavator has a working arm composed of components such as a boom and an arm. In order to operate the working arm, an elastic member such as a hydraulic cylinder is attached to the working arm via a rotating shaft that is free to rotate (rotatably). At this time, the boom or arm, which is a working arm, often has a welded structure of a box-shaped steel plate. The rotating shaft to which the hydraulic cylinder is attached is supported by a bearing member called a boss provided on the side plate constituting the boom or arm. This boss is often fixed to the side plate by welding.

The boss fixed to the side plate receives loads in various directions from the hydraulic cylinder via the rotating shaft. Therefore, various stresses are generated in the welded portion where the side plates and the upper and lower plates of the boom or arm are joined, depending on the movement of the boom or arm, their load conditions, and the like. In particular, due to the out-of-plane deformation of the side plate, bending deformation occurs in the welded portion with the upper and lower plates. The side plates and upper and lower plates are often manufactured with a plate thickness of about 10 mm to 30 mm in order to increase the rigidity of the boom and arm. At the time of welding, the corners of the end faces of the side plates that abut against the upper and lower plates are notched, which are called grooves, and the weld metals are laminated over a plurality of layers to fix them to each other. At this time, in the welded portion between the side plate and the upper and lower plates, there is a portion along the end face called a non-welded portion that is not partially welded.

When bending deformation acts on this welded part, fatigue cracks may occur due to the extremely high stress concentration that occurs at the boundary between the non-welded part and the weld metal. Since this non-welded portion is inside the box-shaped structure and cannot be easily observed from the outside, it tends to be a problem in ensuring the long-term reliability of the product. As a method for reducing the stress generated at the tip of the weld non-welded portion, those described in

Patent Documents

1 and 2 are known.

The technique described in Patent Document 1 is to reduce the stress concentration rate by performing a hole having a certain curvature at the tip of a non-welded portion generated when welding metal plates orthogonal to each other. Further, by press-fitting a pin into the hole, compressive residual stress is applied to the inner surface of the hole, and cracks are less likely to occur.

The technique described in Patent Document 2 is a structure in which a metal rib is welded to the back surface of a metal deck plate, and a groove is formed in the vicinity of the welded portion of the deck plate, and the groove portion is formed when bending deformation acts on the deck plate. By positively deforming the welded portion, the stress of the welded portion is reduced.

Japanese Unexamined Patent Publication No. 2006-142637 Japanese Unexamined Patent Publication No. 2016-205024

However, the prior art described in

Patent Documents

1 and 2 has the following problems.

By processing a hole having a certain curvature at the tip of the weld non-welded portion as in the technique described in Patent Document 1, the stress generated in this portion can be reduced. Further, by press-fitting a pin into the hole to apply compressive residual stress, the fatigue crack generation life and the extension life can be further extended. However, hole drilling and pin press-fitting to the tip of the non-welded part can be performed only when the part is accessible from the outside, and for the non-welded part existing inside the box-shaped closed space. I can't work.

The technique described in Patent Document 2 has an effect of improving fatigue life in that by forming a groove on the surface of the deck plate, the deck plate can be positively deformed in this groove and the deformation of the welded portion in the vicinity can be reduced. Can be expected. However, since the plate thickness of the grooved portion is smaller than that of the deck plate without the groove, the tensile strength, bending strength, and rigidity of the groove portion are reduced, and the original portion without the groove is originally formed. The mechanical characteristics of the designed plate thickness cannot be utilized.

In view of the above problems, an object of the present invention is to reduce the stress or strain of a welded portion in which a non-welded portion is present, and to improve the fatigue life of the welded portion while maintaining strength and rigidity. To provide the structure.
Issues, configurations and effects other than the above will be clarified by the following embodiments.

In order to achieve the above object, one of the typical welded structures of the present invention is a welded structure in which the end face of one plate is in contact with the surface of the other plate and fillet welding is performed to fix the two plates. There is an unwelded non-welded portion between the end face of the one plate material and the surface of the other plate material, and the weld metal for fillet welding is present in the one plate material. A groove is formed in the direction along the non-welded portion from the side surface on the opposite side.

According to the present invention, when an out-of-plane bending deformation acts on a plate material with a groove, the plate material with a groove and the other plate material are elastically deformed in a direction in which the opening of the groove opens and closes. The bending stress of the welded portion including the non-welded portion generated at the boundary with and is relaxed, and the fatigue life of the welded portion including the non-welded portion is extended. Therefore, the durability and reliability of the welded structure are improved.
Issues, configurations and effects other than those described above will be clarified by the following description of the embodiments.

FIG. 1 is a side view showing an overall configuration showing a first embodiment of the welded structure of the present invention. FIG. 2 is a view at the time of deformation in the first embodiment of the welded structure of the present invention. FIG. 3 is a characteristic diagram showing the relationship between the value obtained by dividing the groove length in the first embodiment of the welded structure of the present invention by the plate thickness of the vertical plate and the stress at the tip of the non-welded portion. FIG. 4 is a characteristic diagram showing the relationship between the value obtained by dividing the distance from the non-welded surface of the groove by the plate thickness of the vertical plate and the stress at the tip of the non-welded portion in the first embodiment of the welded structure of the present invention. be. FIG. 5 is a diagram showing an example of deformation when the groove is close to the end face in the welded structure of the present invention. FIG. 6 is a characteristic diagram showing the relationship between the value obtained by dividing the width of the groove opening in the first embodiment of the welded structure of the present invention by the plate thickness of the vertical plate and the stress at the tip of the non-welded portion. FIG. 7 is a side view showing an overall configuration for explaining the distance from the bottom of the groove to the surface of the weld metal in the first embodiment of the welded structure of the present invention. FIG. 8 is a side view showing an example of a hydraulic excavator in the first application example of the welded structure of the present invention. FIG. 9 is a cross-sectional view showing an example of a boom of a hydraulic excavator in a first application example of the welded structure of the present invention, and is a diagram showing a first deformed state. FIG. 10 is a cross-sectional view showing an example of a boom of a hydraulic excavator in a first application example of the welded structure of the present invention, and is a diagram showing a second deformed state. FIG. 11 is a side view showing an example of a dump truck in a second application example of the welded structure of the present invention. FIG. 12 is a perspective view showing an example of a chassis frame of a dump truck in a second application example of the welded structure of the present invention. FIG. 13 is a cross-sectional view showing an example of a chassis frame of a dump truck in a second application example of the welded structure of the present invention. FIG. 14 is a plan view showing an example of a railroad bogie frame in a third application example of the welded structure of the present invention. FIG. 15 is a cross-sectional view showing an example of a railroad bogie frame in a third application example of the welded structure of the present invention. FIG. 16 is a side view showing an overall configuration showing a second embodiment of the welded structure of the present invention. FIG. 17 is a side view showing an overall configuration showing a third embodiment of the welded structure of the present invention.

Hereinafter, embodiments of the welded structure of the present invention will be described with reference to the drawings.

[First Embodiment]
(overall structure)
The overall configuration of the first embodiment of the welded structure of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing an overall configuration showing a welded structure according to the first embodiment of the present invention. FIG. 2 is a view when the welded structure of FIG. 1 is deformed.

In FIG. 1, two steel plates of the vertical plate 1 and the horizontal plate 3 are assembled so as to be orthogonal to each other. The vertical plate 1 is arranged with the longitudinal direction as the vertical direction, and the horizontal plate 3 is arranged with the longitudinal direction as the horizontal direction. The end surface 2 on the lower side (horizontal plate 3 side) of the vertical plate 1 is parallel to the upper surface (vertical plate 1 side) surface of the horizontal plate 3, and the end surface 2 of the vertical plate 1 abuts on the upper surface of the horizontal plate 3. In order to join these plates together, the vicinity of the corner where the vertical plate 1 and the horizontal plate 3 meet is welded. At this time, the side to be welded is a corner portion on the opposite side to the groove 10 described later. In order to firmly weld the vertical plate 1 and the horizontal plate 3, a thickened portion called a groove 4 is processed at the lower corner portion of the vertical plate 1 on the welding side. A plurality of layers of the weld metal 5 are piled up so as to fill the groove 4, and the vertical plate 1 and the horizontal plate 3 are joined. The weld metal 5 is formed with dimensions having a vertical leg length 6 and a horizontal leg length 7. Generally, the vertical leg length 6 is often constructed with a plate thickness D1 or more of the vertical plate 1.

The region where the weld metal 5 sandwiched between the end face 2 and the horizontal plate 3 does not reach is the non-welded portion 8, and the boundary with the weld metal 5 on the non-welded portion 8 side is the tip 9 of the non-welded portion. The shape of the tip 9 of the non-welded portion often has a radius of curvature of several tens of microns and exhibits a crack shape.

Since the weld metal 5 is laminated at a high temperature, the volume shrinks in the cooling process. When the vertical plate 1 and the horizontal plate 3 are fixed in position by a holding jig or the like during welding, the contraction force of the weld metal 5 causes a tensile force on the surface of the groove 4 and the horizontal plate 3 in contact with the weld metal 5. Occurs. This is called welding residual stress and often causes a decrease in the strength of the welded portion.

In the first embodiment, the groove 10 parallel to the end surface 2 of the vertical plate 1 is processed on the back surface 12 on the opposite side of the surface 11 on which the groove 4 is processed. The groove 10 is formed from the back surface 12 on the opposite side where the weld metal 5 is present, with a predetermined length (length in the depth direction) D2 in the direction along the non-welded portion 8.

FIG. 2 shows a deformation diagram when a load from right to left in the figure (arrow in FIG. 2) is applied to the vertical plate 1. In this case, stress in the tensile direction is generated on the surface 11 on which the groove 4 of the vertical plate 1 is machined, and stress in the compression direction is generated on the back surface 12. Compressive stress is often generated at the tip 9 of the non-welded portion, but due to the welding residual stress after welding, tensile stress close to the yield point of the materials constituting the vertical plate 1 and the horizontal plate 3 is generated at this portion. doing. Therefore, when the bending deformation of the vertical plate 1 is repeated, the stress is repeated in the tensile stress field at the tip 9 of the non-welded portion. Then, fatigue cracks are likely to occur due to the extremely large stress concentration at the tip 9 of the non-welded portion.

However, when the vertical plate 1 is bent and deformed, the opening of the groove 10 of the present invention is deformed so as to close, so that the deformation (strain) of the tip 9 of the non-welded portion is compared with the case where the groove 10 is not provided. It becomes smaller. As a result, the life until the occurrence of fatigue cracks can be extended, and the rate of crack growth can be reduced.

(Groove length)
An example of the groove length in the first embodiment will be described with reference to the drawings. In FIG. 3, the value obtained by dividing the length D2 of the groove 10 by the plate thickness D1 of the vertical plate 1 (horizontal axis) and the stress width near the tip 9 of the non-welded portion are divided by the nominal stress width due to bending deformation of the vertical plate 1. It is a characteristic diagram which showed the relationship of values (vertical axis).

In FIG. 3, the value obtained by dividing the length D2 of the groove 10 by the plate thickness D1 of the vertical plate 1 is around 0.25, and the nominal stress due to bending deformation of the vertical plate 1 with respect to the stress width near the tip 9 of the non-welded portion. The value divided by the width indicates the minimum value. When the length of the groove 10 is short, a load acts in the direction of the arrow in FIG. 2, and a tensile stress is generated at the tip 9 of the non-welded portion. Then, as the length of the groove 10 becomes longer, the absolute value of the tensile stress decreases. On the other hand, if the length of the groove 10 is too long, compressive stress is generated at the tip 9 of the non-welded portion. Therefore, the stress width, which is the absolute value of stress, increases on the contrary. In the present embodiment, the length D2 of the groove 10 is set to 20% to 30% of the plate thickness D1 of the vertical plate 1, so that the stress width of the non-welded portion tip 9 can be minimized, and as a result, the stress width can be minimized. The life until the occurrence of fatigue cracks can be extended, and the rate of crack growth can be reduced.

(Distance from the end face of the groove)
An example of the distance from the end face of the groove in the first embodiment will be described with reference to the drawings. FIG. 4 shows the value obtained by dividing the distance D3 from the end surface 2 of the groove 10 by the plate thickness D1 of the vertical plate 1 (horizontal axis) and the stress width near the tip 9 of the non-welded portion as the nominal stress width due to bending deformation of the vertical plate 1. It is a characteristic diagram which showed the relationship of the value (vertical axis) divided by. Further, FIG. 5 is a diagram showing an example of deformation when the groove is close to the end face.

In FIG. 4, the value obtained by dividing the distance D3 from the end surface 2 of the groove 10 by the plate thickness D1 of the vertical plate 1 is around 0.3, and the bending deformation of the vertical plate 1 with respect to the stress width near the tip 9 of the non-welded portion. The value divided by the nominal stress width according to is the minimum. When the groove 10 is close to the end surface 2, the member immediately below the opening of the groove 10 is deformed as shown in FIG. 5, and the contact area between the end surface 2 and the horizontal plate 3 becomes small. Therefore, as the value on the horizontal axis becomes smaller as shown in FIG. 4, the stress width in the vicinity of the tip 9 of the non-welded portion increases. Further, if the groove 10 is greatly separated from the end surface 2, the effect of deformation of the opening of the groove 10 becomes small. Therefore, as shown in FIG. 4, when the value on the horizontal axis becomes larger than a predetermined value, the stress width in the vicinity of the tip 9 of the non-welded portion becomes equal when there is no groove 10.

In the present embodiment, the stress width of the non-welded portion tip 9 can be minimized by setting the distance D3 from the end surface 2 of the groove 10 to 20% to 40% of the plate thickness D1 of the vertical plate 1. As a result, the life until the occurrence of fatigue cracks can be extended, and the rate of crack growth can be reduced.

(Width of groove opening)
An example of the width of the groove opening in the first embodiment will be described with reference to the drawings. FIG. 6 shows the relationship between the value obtained by dividing the width D4 of the opening of the groove 10 in the opening direction by the plate thickness D1 of the vertical plate 1 (horizontal axis) and the stress width (vertical axis) near the tip 9 of the non-welded portion. It is a characteristic diagram.

In FIG. 6, the value obtained by dividing the width (width of the groove in the longitudinal direction of the vertical plate 1) D4 of the groove 10 by the plate thickness D1 of the vertical plate 1 is around 0.1, and near the tip 9 of the non-welded portion. The stress width is the minimum. If the width of the opening of the groove 10 is too small, the opening / closing deformation of the groove 10 becomes small, and the deformation of the groove 10 becomes negligible with respect to the bending deformation of the vertical plate 1, so that the tip of the non-welded portion The stress reduction effect in the vicinity of 9 becomes small. On the other hand, if the width of the opening of the groove 10 is large, the rigidity of the bending deformation of the vertical plate 1 becomes too small, and the stress in the vicinity of the tip 9 of the non-welded portion becomes large.

In the present embodiment, the stress width of the non-welded portion tip 9 can be minimized by setting the width D4 of the opening of the groove 10 in the range of 5% to 15% of the plate thickness D1 of the vertical plate 1. As a result, the life until the occurrence of fatigue cracks can be extended, and the rate of crack growth can be reduced.

(Distance from the bottom of the groove to the surface of the weld metal)
The distance from the bottom of the groove to the surface of the weld metal in the first embodiment will be described with reference to the drawings. FIG. 7 is a side view showing an overall configuration for explaining a distance E from the bottom 15 of the groove to the surface of the weld metal 5 in the first embodiment of the welded structure of the present invention.

In FIG. 7, the distance E from the bottom portion 15 of the groove 10 to the surface of the weld metal 5 is the distance E from the bottom portion 15 to the surface 11 when a line parallel to the end surface 2 is extended from the bottom portion 15 which is the innermost portion of the groove 10. It is the distance to the position of the surface of the weld metal 5 on the side. The distance E increases at the position where the weld metal 5 exists as compared with the position where the weld metal 5 does not exist, and prevents a decrease in strength. In FIG. 7, the distance E is a position where the plate thickness D1 or more of the vertical plate 1 is obtained.

When a tensile load is applied to the vertical plate 1, the plate thickness of the portion where the groove 10 is present is smaller than the plate thickness of the portion where the groove 10 is not present. Is a concern. In the present embodiment, since the plate thickness of the portion where the groove 10 exists is equal to or greater than the plate thickness D1 of the vertical plate 1, the tensile strength does not decrease. Further, the bottom portion 15 of the groove 10 is formed in an arc shape having a radius of curvature of half the height of the opening of the groove 10. As a result, the occurrence of cracks at the bottom 15 of the groove 10 can be prevented as much as possible.

In the present embodiment, the stress width of the non-welded portion tip 9 can be minimized due to the presence of the groove 10, and as a result, the life until the occurrence of fatigue cracks can be extended and the crack growth rate can be reduced. Further, it also has an effect of not causing a decrease in strength even when a tensile load is applied to the vertical plate 1.

(First application example)
A first application example of the welded structure of the present invention will be described with reference to the drawings. FIG. 8 is a side view showing an example of a hydraulic excavator in the first application example of the welded structure of the present invention, and shows an example of excavation in the hydraulic excavator. 9 and 10 are cross-sectional views showing an example of the boom of the hydraulic excavator in the first application example of the welded structure of the present invention, and are cross-sectional views taken along the line AA'of FIG. FIG. 9 shows the first deformed state, and FIG. 10 shows the second deformed state.

In FIG. 8, the hydraulic excavator 16 includes a self-propelled crawler-type lower traveling body 17 and an upper swivel body 19 rotatably mounted on the lower traveling body 17 via a swivel bearing device 18. .. A work front 20 is attached to the front end of the upper swing body 19 so as to be able to move up and down (rotate).

The work front 20 is an articulated work device for performing excavation work and the like, and the boom 21 and the arm 22 constituting the work arm and the bucket 23 as a work tool (attachment) attached to the tip of the work arm. It is composed of and.

The boom 21 is rotated by a pair of boom cylinders 24.

FIG. 9 is a cross-sectional view of the boom 21 of the hydraulic excavator 16 cut at the position AA'plane (FIG. 8) of the boom center boss 28, showing the deformed state of the boom 21 when a pushing load is applied to the bucket 23. It is a figure which shows. FIG. 10 is a cross-sectional view of the boom 21 of the hydraulic excavator 16 cut at the position AA'plane (FIG. 8) of the boom center boss 28, and shows the deformed state of the boom 21 when a pull load is applied to the bucket 23. It is a figure.

The boom 21 and arm 22 have a box-shaped structure having a rectangular cross section. The box-shaped structure comprises a side plate 25 which is a pair of plate members facing each other at intervals in the width direction of the hydraulic excavator 16, an upper plate 26 which is a plate member arranged on the upper end side of both side plates 25, and both side plates 25. It includes a lower plate 27 which is a plate member arranged on the lower end side. Here, a box-shaped structure is formed by joining the upper plate 26 and both side plates 25, and the lower plate 27 and both side plates 25 by welding, respectively.

In this application example, a groove 32 is machined inside the both side plates 25. Further, on the outside of the both side plates 25, a groove is machined at the welding position with the upper plate 26 and the lower plate 27 at the time of welding. Then, when joining the upper plate 26 and the lower plate 27 and the both side plates 25, welding is performed from the outside of the upper plate 26 and the lower plate 27 at the groove portion. At that time, a non-welded portion 31 is formed inside the box-shaped structure between the both side plates 25 and the upper plate 26 and the lower plate 27. The non-welded portion 31, the groove 32, and the tip 33 of the non-welded portion in FIGS. 9 and 10 correspond to the non-welded portion 8, the groove 10, and the tip 9 of the non-welded portion in FIG. Further, the side plates 25 of FIGS. 9 and 10 correspond to the vertical plate 1 of FIG. 1, and the upper plate 26 and the lower plate 27 of FIG. 13 correspond to the horizontal plate 3 of FIG.

The load from the boom cylinder 24 shown in FIG. 8 acts on the boss 28 of the boom 21 of the hydraulic excavator 16 shown in FIGS. 9 and 10 via the connecting pin inserted into the pin insertion hole 29. Due to this load, as shown in FIGS. 9 and 10, the upper plate 26, the lower plate 27, and the side plate 25 of the boom 21 are bent and deformed in the out-of-plane direction (the direction toward the outer surface side or the direction toward the inner surface side of the structure). Occurs.

When the side plate 25 is bent and deformed in the out-of-plane direction, the groove 32 reduces the stress (strain) of the tip 33 of the non-welded portion by deforming the opening, and as a result, until the occurrence of fatigue cracks. The life can be extended and the crack growth rate can be reduced. Therefore, the strength reliability of the hydraulic excavator can be improved.

(Second application example)
A second application example of the welded structure of the present invention will be described with reference to the drawings. FIG. 11 is a side view showing an example of a dump truck in a second application example of the welded structure of the present invention, and shows an example of a large dump truck that transports minerals, earth and sand, etc. mined in a mine. FIG. 12 is a perspective view showing an example of a chassis frame of a dump truck in a second application example of the welded structure of the present invention. FIG. 13 is a cross-sectional view showing an example of the chassis frame of the dump truck in the second application example of the welded structure of the present invention, and shows a cross-sectional view of the base frame in the chassis frame.

In FIG. 11, the dump truck 34 is a large-sized transport vehicle, and is composed of a vehicle body 35 having a sturdy frame structure and a loading platform 36 mounted on the vehicle body 35 so as to be tilted (undulating). The vehicle body 35 includes a frame 39, a building 37, a cab 38, and the like.

In FIG. 12, the frame 39 is a frame constituting the chassis of the vehicle body 35, and the frame 39 is formed as a strong support structure (can manufacturing structure by welding) extending in the front-rear direction. The frame 39 is composed of a base frame 40 extending in the front-rear direction and an upper cross beam 41 arranged in an intermediate portion of the base frame 40 in the front-rear direction.

Here, the base frame 40 is provided with a plurality of seats 42 that receive the load from the tires. Then, a complicated load due to the traveling terrain acts on the base frame 40.

FIG. 13 is a cross-sectional structure view of the base frame 40 cut along the B portion plane in FIG. The cross section is a rectangular box-shaped structure. The box-shaped structure includes a side plate 43 which is a pair of plate members facing each other at intervals in the width direction of the dump truck 34, an upper plate 44 which is a plate member arranged on the upper end side of both side plates 43, and both side plates 43. It is provided with a lower plate 45 which is a plate member arranged on the lower end side. Here, a box-shaped structure is formed by joining the both side plates 43 and the upper plate 44, and the both side plates 43 and the lower plate 45 by welding, respectively.

In this application example, a groove 47 is machined inside the side plate 43. Further, a groove is machined on the side plate 43 at an outer welding position at the time of welding. When the upper plate 44 and the lower plate 45 are welded to the side plate 43, they are welded from the outside of the side plate 43 using the groove portion. At that time, a non-welded portion 46 is formed inside the box-shaped structure between the both side plates 43 and the upper plate 44 and the lower plate 45. The non-welded portion 46, the groove 47, and the tip 48 of the non-welded portion in FIG. 13 correspond to the non-welded portion 8, the groove 10, and the tip 9 of the non-welded portion in FIG. Further, the side plate 43 of FIG. 13 corresponds to the vertical plate 1 of FIG. 1, and the upper plate 44 and the lower plate 45 of FIG. 13 correspond to the horizontal plate 3 of FIG.

When the side plate 43 is bent and deformed in the out-of-plane direction, the groove 47 reduces the stress (strain) of the tip 48 of the non-welded portion by deforming the opening thereof, and as a result, until fatigue cracks occur. Can extend the life of the and also reduce the rate of crack growth. Therefore, the strength reliability of the dump truck can be improved.

(Third application example)
A third application example of the welded structure of the present invention will be described with reference to the drawings. FIG. 14 is a plan view showing an example of a railroad bogie frame in a third application example of the welded structure of the present invention. FIG. 15 is a cross-sectional view showing an example of a railroad bogie frame in a third application example of the welded structure of the present invention.

In FIG. 14, the bogie frame 49 is provided with a pair of side beams 50 separated along the vehicle traveling direction and a pair of cross beams 51 provided along the sleeper direction and connecting the side beams 50 to each other. Has. The air spring receiving seat 52 on which the air spring that elastically supports the vehicle body is placed is provided on the carriage frame 49 so as to be connected to both ends of the cross beam 51 in the sleeper direction and the central portion of the side beam 50 in the vehicle traveling direction. ..

FIG. 15 is a cross-sectional structural view of the side beam 50 cut at the CC'plane in FIG. The cross-sectional shape is a rectangular box-shaped structure. The box-shaped structure includes a side plate 53 which is a pair of plate members facing each other in the width direction in the traveling direction of the vehicle, an upper plate 54 which is a plate member arranged on the upper end side of both side plates 53, and both side plates 53. It is provided with a lower plate 55 which is a plate member arranged on the lower end side of the above. Here, a box-shaped structure is formed by joining the both side plates 53 and the upper plate 54, and the both side plates 53 and the lower plate 55 by welding, respectively.

In this application example, a groove 57 is machined inside the upper plate 54 and the lower plate 55. Grooves are machined at the outer welding positions on the upper plate 54 and the lower plate 55 at the time of welding. When the side plate 53 is welded to the upper plate 54 and the lower plate 55, it is welded to the side plate 53 from the outside using a groove portion. At that time, a non-welded portion 56 is formed inside the box-shaped structure between the upper plate 54 and the lower plate 55 and the both side plates 53. The non-welded portion 56, the groove 57, and the tip 58 of the non-welded portion in FIG. 15 correspond to the non-welded portion 8, the groove 10, and the tip 9 of the non-welded portion in FIG. Further, the upper plate 54 and the lower plate 55 in FIG. 15 correspond to the vertical plate 1 in FIG. 1, and the side plate 53 in FIG. 15 corresponds to the horizontal plate 3 in FIG.

When the upper plate 54 and the lower plate 55 are bent and deformed in the out-of-plane direction of the groove 57, the opening thereof is deformed to reduce the stress (strain) of the tip 58 of the non-welded portion, resulting in fatigue. The life until the occurrence of cracks can be extended, and the rate of crack growth can be reduced. Therefore, it is possible to improve the strength reliability of the bogie frame of the railway vehicle.

[Second Embodiment]
A second embodiment of the welded structure of the present invention will be described with reference to the drawings. FIG. 16 is a side view showing an overall configuration showing a welded structure according to a second embodiment of the present invention. In the second embodiment, the points different from those in the first embodiment are mainly described, the same parts are designated by the same reference numerals, and the same description is omitted unless otherwise specified.

The vertical plate 1'in FIG. 16 basically corresponds to the vertical plate 1 of the first embodiment, but the vertical plate 1'is formed with a groove 13 instead of the groove 10. Then, as shown in FIG. 16, the groove 13 is formed from the back surface 12 side as a groove having a predetermined opening width F including the non-welded portion 8 between the vertical plate 1'and the horizontal plate 3. .. The groove 13 is formed by, for example, machining. The bottom portion 14, which is the innermost portion of the groove 13, is machined on an arc having a radius of curvature of the width F of the opening of the groove. The bottom portion 14 of the groove 13 serves as a boundary with the weld metal 5 and also serves as a non-welded portion tip 9.

According to this embodiment, since the length of the non-welded portion 8 can be controlled in advance to a dimension that does not vary by machining or the like, the stress width generated at the tip 9 of the non-welded portion can be predicted by numerical calculation such as the finite element method. It becomes. Further, since the tip 9 of the non-welded portion has an arc shape having a constant curvature, stress concentration can be reduced, and as this effect, the life until the occurrence of fatigue cracks is extended and the crack growth rate is reduced. can.

[Third Embodiment]
A third embodiment of the welded structure of the present invention will be described with reference to the drawings. FIG. 17 is a side view showing an overall configuration showing a third embodiment of the welded structure of the present invention. In the third embodiment, the points different from those in the first embodiment are mainly described, the same parts are designated by the same reference numerals, and the same description is omitted unless otherwise specified.

In the present embodiment, unlike the vertical plate 1 of the first embodiment, the vertical plate 1 ″ is not perpendicular to the horizontal plate 3 but is welded with an inclination of a constant angle θ from the vertical. The direction of inclination is opposite to the surface on which the groove 4 is machined (the surface on the weld metal 5 side). The lower end surface 2 is parallel to the upper side of the horizontal plate 3. A groove 10'is formed on the upper portion of the non-welded portion 8 and on the side surface on the side where the weld metal 5 is not exposed on the surface. The groove 10'does not necessarily have to be parallel to the end surface 2 on the non-welded portion 8 side. In FIG. 16, the groove 10'is tilted by a certain angle θ with the opening side of the groove 10'lower than the parallel surface of the end surface 2. The groove 10 ″ is machined at an appropriate angle during machining of the vertical plate 1 ″ before welding.

According to this embodiment, since the vertical plate 1 ″ is tilted with respect to the horizontal plate 3, the groove 4 can be clearly observed at the time of welding, and the groove 4 can be easily accessed by the welding torch, and the production efficiency is improved. Then, even when bending deformation acts on the vertical plate 1'', the groove 10'is elastically deformed, so that the stress width of the tip 9 of the non-welded portion can be reduced and the fatigue life of the welded structure can be improved. ..

The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace other configurations with respect to a part of the configurations of each embodiment.

1, 1', 1'' ... Vertical plate, 2 ... End face, 3 ... Horizontal plate, 4 ... Groove, 5 ... Welded metal, 6 ... Vertical leg length, 7 ... Horizontal leg length, 8, 31, 46, 56 ... No Welded part, 9, 33, 48, 58 ... Non-welded part tip, 10, 10', 13, 32, 47, 57 ... Groove, 11 ... Face, 12 ... Back side, 14, 15 ... Bottom, 16 ... Hydraulic excavator, 17 ... lower traveling body, 18 ... swivel bearing device, 19 ... upper swivel body, 20 ... work front, 21 ... boom, 22 ... arm, 23 ... bucket, 24 ... boom cylinder, 25, 43, 53 ... side plate, 26, 44, 54 ... upper plate, 27, 45, 55 ... lower plate, 28 ... boss, 29 ... pin insertion hole, 34 ... dump truck, 35 ... car body, 36 ... loading platform, 37 ... building, 38 ... cab, 39 ... frame , 40 ... base frame, 41 ... upper cross beam, 42 ... seat, 49 ... trolley frame, 50 ... side beam, 51 ... cross beam, 52 ... air spring seat, D1 ... plate thickness, D2 ... groove length, D3 ... Distance, D4 ... width, E ... distance, F ... width, θ ... constant angle

Claims

It is a welding structure in which the end surface of one plate material is in contact with the surface of the other plate material and fillet welding is performed to fix the two plate materials, and is between the end surface of the one plate material and the surface of the other plate material. There is a non-welded portion that is not welded in part, and a groove is formed in the one plate material in the direction along the non-welded portion from the side surface opposite to the side where the weld metal for fillet welding is present. Welded structure characterized by being
In the welded structure according to claim 1,
A welded structure characterized in that the length of the groove is 20% to 30% of the plate thickness of the one plate material.
In the welded structure according to claim 1,
A welded structure characterized in that the distance from the non-welded portion to the groove is 20% to 40% of the plate thickness of the one plate material.
In the welded structure according to claim 1,
A welded structure characterized in that the width of the groove is 5% to 15% of the plate thickness of the one plate material.
In the welded structure according to claim 1,
A welded structure characterized in that the distance from the bottom of the groove to the surface of the weld metal is equal to or greater than the plate thickness of one of the plate materials.
In the welded structure according to claim 1,
The groove is formed with a certain width including the non-welded portion, the bottom portion of the groove is a boundary portion with the weld metal of the fillet weld, and the shape of the bottom portion is formed in an arc shape. A welded structure characterized by being made.