JP2019155391A - Fillet welding joint and manufacturing method thereof - Google Patents

Abstract

To provide a fillet welding joint and a manufacturing method thereof hardly causing a fatigue crack with a root part as a starting point, while reducing stress concentration to a toe part.SOLUTION: In a fillet welding joint (1), an upper plate (2) and a lower plate (3) comprise respectively flat parts (21 and 31) and inclined parts (22 and 32), and an end part (2T) of the upper plate (2) is opposed to an upper side surface of the inclined part (32) of the lower plate (3), and is arranged so that an angle (α) formed by the inclined part (22) of the upper plate (2) and the inclined part (32) of the lower plate (3) becomes 90° or more, and is also formed so that a center (4C) of a throat thickness of a welding part (4) formed between the end part (2T) of the upper plate (2) and the upper side surface of the inclined part (32) of the lower plate (3), is positioned on a lower side (D) than respective ones of a plate thickness central axis (2a) of the flat part (21) of the upper plate (2) and a plate thickness central axis (3a) of the flat part (31) of the lower plate (3).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fillet welded joint and a method for manufacturing the same.

  In recent years, in automobile-related fields, in order to reduce vehicle weight from the viewpoint of improving fuel efficiency, it is possible to reduce the thickness of metal plates such as steel plates used for structural members such as undercarriage parts while maintaining or improving their strength. It is being considered.

As a structural member such as an undercarriage part of an automobile, a fillet welded joint in which two steel plates are overlapped and welded is known. Here, Fig.5 (a) is a cross section along the plate | board thickness direction of the welding location in common fillet welded joint 1 '(Note that this cross section is a cross section perpendicular to the weld line. The same applies hereinafter). of a cross-sectional view and FIG. 5 (b) is a schematic view showing a state fillet weld joint tensile the load F _P 1 'is applied (axial force loading) of FIG. 5 (a).
As shown in FIG. 5 (a), a general fillet welded joint 1 'is formed by overlaying an upper plate 2' and a lower plate 3 'and welding the end portion of the upper plate 2'. Is formed. In such a fillet welded joint 1 ′, the thickness center axis 2′a of the upper plate 2 ′ and the thickness center axis 3′a of the lower plate 3 ′ are not on the same axis. when used as a structural member such as parts, it takes a large rotation moment in the weld 4 'by the action of the tensile load F _P as shown in FIG. 5 (b), in the root portion 4'R, the upper plate 2 'and lower plate 3' so that the tensile stress f _P acting in the direction in which the away from each other occurs. As a result, the fillet welded joint 1 ′ is such that the root portion 4′R is likely to be the starting point of fatigue cracks.

In the fillet welded joint, many studies have been made so far on the technique for improving the fatigue strength of the welded portion. For example, in Patent Document 1, in the case of fillet welding the end portions of two steel plates, A stepped portion bent and bent downward is formed on the overlapping end portion of the one side steel plate, and an end surface of the other side steel plate is brought into contact with a bent portion of the stepped portion formed on the one side steel plate, The deviation between the central axis of the one side steel plate and the central axis of the other side steel plate is less than half of the average value of the thickness of the one side steel plate and the thickness of the other side steel plate. Is disclosed.
According to the technique disclosed in Patent Document 1, it is said that stress concentration at the toe portion of the welded portion can be relaxed and weld fatigue strength can be improved.

Japanese Patent Laid-Open No. 9-141427

  However, the technique disclosed in Patent Document 1 is based on the difference between the central axis of one side steel plate (lower plate) and the central axis of the other side steel plate (upper plate). Although there is a requirement that the thickness is less than half of the average value with respect to the thickness, an aspect in which the central axis of each steel sheet is not on the same axis (that is, an aspect in which the central axis of the thickness does not match) is included. Therefore, in the case of such an aspect, similarly to the above-described general fillet welded joint 1 ′, a rotational moment is applied to the welded portion, and the central axis of each steel plate has no axial deviation (that is, Even in the case where the thickness center axis of each steel plate is on the same axis), in the structure of the fillet welded joint disclosed in Patent Document 1, the root portion is caused by the action of the tensile load applied to the entire joint. As a result, the same tensile stress as that of the general fillet welded joint 1 'described above is generated. There is a possibility that fatigue cracks that starting from over isolation portion occurs.

  Therefore, an object of the present invention is to provide a fillet welded joint in which a fatigue crack starting from the root portion is less likely to occur while reducing stress concentration on the toe portion and a manufacturing method thereof.

One aspect (aspect 1) of the present invention is a fillet welded joint composed of two metal plates, an upper plate and a lower plate,
Each of the upper plate and the lower plate includes a flat portion and an inclined portion extending to the end while inclining downward from the flat portion, and an end portion of the upper plate is an inclined portion of the lower plate. It is disposed so as to face the upper surface and the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is 90 ° or more,
The center of the throat thickness of the welded portion formed between the end portion of the upper plate and the upper surface of the inclined portion of the lower plate is the thickness axis of the flat portion of the upper plate and the flat portion of the lower plate. It is the said fillet weld joint formed so that it may be located below each plate thickness center axis | shaft.

In the fillet welded joint of aspect 1, the upper plate and the lower plate each have a flat portion and an inclined portion that extends from the flat portion to the end while being inclined downward, and the end portion of the upper plate is It is arranged so as to face the upper surface of the inclined portion of the lower plate, and the center of the throat thickness of the weld formed between the end of the upper plate and the upper surface of the inclined portion of the lower plate is It is formed so that it is located below the center thickness axis of the flat part of the plate and the center thickness axis of the flat part of the lower plate. By deforming so as to protrude upward, a compressive stress acting in a direction in which the upper plate and the lower plate approach each other can be generated in the root portion. Thereby, the fillet welded joint according to the first aspect is less prone to fatigue cracks starting from the root portion.
Furthermore, since the fillet welded joint of the present aspect 1 is arranged so that the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is 90 ° or more, the rising angle of the toe portion at the welded portion Can be reduced, and the stress concentration on the toe can be reduced.
From the above, the fillet welded joint of the present aspect 1 is less susceptible to fatigue cracks starting from the root portion while reducing stress concentration on the toe portion, and exhibits even more excellent fatigue characteristics. Can do.

  In addition, the fillet welded joint of this aspect 1 has structural or manufacturing restrictions such as making the deviation of the center axis of the thickness of each metal plate (upper plate and lower plate) within a predetermined range. Since there are few, there exists an advantage that it is hard to produce that the application location of a joint is limited or a high precision is requested | required for positioning of each metal plate.

  Moreover, in another aspect (aspect 2) of the present invention, in the fillet welded joint according to aspect 1, the weld has a peening mark on the toe.

  Since the fillet welded joint of the present aspect 2 has a peening mark at the toe portion of the welded portion, the fatigue strength of the toe portion is high, and fatigue cracks starting from the toe portion also occur more. It has become difficult.

Still another aspect (aspect 3) of the present invention is a method for manufacturing the fillet welded joint according to aspect 1 or 2,
Forming the inclined portion on each of the upper plate forming plate member and the lower plate forming plate member having a flat structure, and producing the upper plate and the lower plate;
The upper plate and the upper plate so that the end portion of the upper plate faces the upper surface of the inclined portion of the lower plate and the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is 90 ° or more. Arranging the lower plate;
Between the end of the upper plate and the upper surface of the inclined portion of the lower plate, the center of the throat is the plate thickness central axis of the flat portion of the upper plate and the plate thickness central axis of the flat portion of the lower plate. And fillet welding so as to be located below each.

  The manufacturing method of the fillet welded joint according to the third aspect includes at least the above-described steps, thereby reducing the stress concentration on the toe part and reducing the occurrence of fatigue cracks starting from the root part. Can be easily manufactured without requiring a difficult process (for example, a process requiring high positioning accuracy).

  According to the present invention, it is possible to provide a fillet welded joint in which a fatigue crack starting from the root portion is less likely to occur and a method for manufacturing the same while reducing stress concentration on the toe portion.

FIG. 1 is a cross-sectional view of a cross section along the thickness direction of a welded portion in a fillet welded joint 1 according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of a welding location in the fillet weld joint 1 of FIG. Figure 3 is a schematic view showing a state where the tensile load F _P is applied to the fillet weld joint 1 in Figure 1. FIG. 4 is a cross-sectional view of a cross section along the plate thickness direction of a welded portion in a fillet weld joint 10 according to another embodiment of the present invention. Fig.5 (a) is sectional drawing of the cross section along the plate | board thickness direction of the welding location in the conventional general fillet welded joint 1 ', FIG.5 (b) is a fillet of Fig.5 (a). load F _P tensile welded joint 1 'is a schematic view showing a state where the action.

  Hereinafter, a preferred embodiment of a fillet welded joint of the present invention will be described in detail with reference to the drawings. In the present specification, the upper side and the lower side are relative positional relationships in the vertical direction (ie, vertical direction) of an object (for example, a joint, an upper plate, a lower plate, a welded portion, etc.) It means a positional relationship including the bottom), and does not mean a limited positional relationship such as directly above and below.

FIG. 1 is a cross-sectional view of a cross section along the plate thickness direction of a welded spot in a fillet welded joint 1 according to an embodiment of the present invention, and FIG. It is sectional drawing. Further, FIG. 3, the load F _P tensile fillet weld joint 1 is a schematic view showing a state where the effect (axial force loading).

A fillet welded joint 1 according to an embodiment of the present invention, as shown in FIGS. 1 and 2, is two steel plates that are relatively positioned above and below (an example of a “metal plate” in the present invention). The upper plate 2 and the lower plate 3 are made of a structure in which the weld plate 4 is joined. As shown in FIG. 1, the upper plate 2 has a flat portion 21 which occupies the most part, has an inclined portion 22 extending to the end 2T while inclined lower side D ₂ from the flat part 21, Similarly the lower plate 3 also has a flat portion 31 which occupies a large part, and an inclined portion 32 extending from the flat part 31 to the end portion 3T while inclined lower side D _2. As shown in FIG. 2, the upper plate 2 and the lower plate 3 have an end 2T of the upper plate 2 facing the upper surface of the inclined portion 32 of the lower plate 3, and the lower portion 3 and the lower portion 3 of the upper plate 2. The angle α formed between the inclined portion 32 of the plate 3 and the upper surface of the inclined portion 32 of the lower plate 3 is arranged such that the angle α formed with the inclined portion 32 is 90 ° or more. A welded portion 4 is formed on the surface.

In addition, in this specification, the edge part of an upper board and a lower board means the part located in the most distal side from a flat part in each inclination part, respectively.
In the present specification, the angle α formed by the inclined portion of the upper plate and the inclined portion of the lower plate is equal to the thickness center axis 2b of the inclined portion of the upper plate and the inclined portion of the lower plate, as shown in FIG. Among the angles formed by the plate thickness center axis 3b, the angle relatively above is indicated.

And in the fillet welded joint 1 of this embodiment, as shown in FIG. 2, the welding part 4 fillet welds between the edge part 2T of the upper board 2, and the upper surface of the inclination part 32 of the lower board 3. As shown in FIG. The center 4C of the throat thickness 4D is lower than each of the plate thickness central axis 2a of the flat portion 21 of the upper plate 2 and the plate thickness central axis 3a of the flat portion 31 of the lower plate 3. It is formed so as to be located in D _2.

Thus, fillet weld joint 1 of the present embodiment, the upper plate 2 and the lower plate 3, respectively a flat 21, 31, the end portion 2T while inclined lower side _{D 2} from the flat part 21 and 31 3T, and the end portion 2T of the upper plate 2 is disposed so as to face the upper surface of the inclined portion 32 of the lower plate 3, and the end portion of the upper plate 2 is further provided. The center 4C of the throat thickness 4D of the welded portion 4 formed between 2T and the upper surface of the inclined portion 32 of the lower plate 3 is the plate thickness central axis 2a of the flat portion 21 of the upper plate 2 and the flat portion of the lower plate 3. because it is formed to be positioned on the lower side D ₂ than each of the thickness center shaft 3a of the 31, as shown in FIG. 3, when the applied load F _P tensile entire joint, the weld 4 by modified as pushed out on the upper side D _1, at the root portion 4R, upper plate 2 and the lower plate 3 with each other A compressive stress fc acting in the approaching direction can be generated. Thereby, the fillet welded joint 1 of the present embodiment is less prone to fatigue cracks starting from the root portion 4R.
Furthermore, since the fillet welded joint 1 of the present embodiment is disposed so that the angle α formed by the inclined portion 22 of the upper plate 2 and the inclined portion 32 of the lower plate 3 is 90 ° or more, the welded portion 4. The rising angle of the toe portion 4T becomes gentle, and the stress concentration on the toe portion 4T can be reduced.
As described above, the fillet welded joint 1 of the present embodiment is less prone to fatigue cracks starting from the root portion 4R while reducing the stress concentration on the toe portion 4T, and has even more excellent fatigue characteristics. It can be demonstrated.

  In addition, the fillet welded joint 1 of the present embodiment has structural or manufacturing restrictions such as making the deviation of the center axis of the plate thickness of each steel plate (upper plate and lower plate) in the conventional range. Since there are few, there exists an advantage that it is hard to produce that the application location of a joint is limited or a high precision is required for positioning of each steel plate.

  Further, in the present invention, the overall shape of the fillet welded joint is not particularly limited as long as the effects of the present invention are not hindered. In addition to the undercarriage parts of the automobile as in the above-described embodiment, any shape according to various uses and the like The overall shape can be adopted.

  Hereinafter, various members constituting the fillet welded joint of the present invention will be described in more detail using the fillet welded joint 1 according to the above-described embodiment.

[Upper plate and lower plate]
In the fillet welded joint 1 of the present embodiment, the upper plate 2 and the lower plate 3 are each formed by bending a portion near the end of the steel plate (that is, a portion corresponding to the welded portion) by an arbitrary bending means. a flat portion 21 and 31, the end portion while inclined lower side _{D 2} from the flat part 21 and 31 2T, and the inclined portion 22, 32 extending to 3T are formed. As shown in FIGS. 1 and 2, the flat portions 21 and 31 and the inclined portions 22 and 32 include the plate thickness central axes 2a and 3a of the flat portions 21 and 31 and the plates of the inclined portions 22 and 32, respectively. In addition, in the fillet welded joint 1 of the present embodiment, the thickness center axis 2a of the flat portion 21 in the upper plate 2 and the flat portion 31 of the lower plate 3 are provided. The plate thickness central axis 3a exists on the same axis (that is, the plate thickness central axis coincides).

  In the present invention, the metal plate used for forming the upper plate and the lower plate is a required characteristic (for example, joint strength or the like) of a structural member (for example, an automobile undercarriage part) to which the fillet welded joint of the present invention is applied. For example, a steel sheet having a tensile strength in the range of 400 MPa to 1300 MPa can be suitably used. Moreover, as long as the steel plate does not impair the effect of this invention, the surface may be plated with zinc etc., and other arbitrary surface treatments may be given.

  In the present invention, the plate material for forming the upper plate and the lower plate (that is, the plate material for forming the upper plate and the plate material for forming the lower plate) is not limited to the above-described steel plate, and the fillet welded joint of the present invention is applied. Any metal plate (for example, an aluminum plate, a stainless steel plate, etc.) according to the required characteristics of the structural member to be used can be employed. Further, the upper plate and the lower plate may be formed of the same type of metal plate or may be formed of different types of metal plates.

In the present invention, the outer shape of the upper plate and the lower plate is not particularly limited as long as it has the above-described flat portion and inclined portion and does not impair the effects of the present invention, and has any outer shape according to various uses. Can be adopted.
It should be noted that the inclination angle of the inclined portion in the upper plate and the lower plate (that is, the angle at which each of the upper plate and the lower plate is inclined downward from the flat portion toward the end, the plate thickness central axis of the flat portion) The angle between the central axis of the inclined portion and the plate thickness center axis is the acute angle) so that the upper plate and the lower plate are opposed to the upper surface of the inclined portion of the lower plate. There is no particular limitation as long as the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is an angle of 90 ° or more when the upper plate and the lower plate are inclined. For example, an arbitrary angle of less than 90 ° (however, the angle at which the sum of the inclination angle of the upper plate and the inclination angle of the lower plate is 90 ° or less) can be adopted, and the angle is preferably 45 ° or less. . The inclination angles of the upper plate and the lower plate may be the same or different between the upper plate and the lower plate.

  In the present invention, the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is not particularly limited as long as it is an angle of 90 ° or more. However, the larger the angle formed (ie, the closer the angle is to 180 °). ), Since the rising angle of the toe portion in the welded portion becomes more gradual, the stress concentration on the toe portion can be further reduced. The angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is an angle of less than 180 °, as is apparent from the structures of the upper and lower plates having the flat portion and the inclined portion, and their arrangement. is there.

  In the present invention, the dimensional shape, thickness, etc. of the upper plate and the lower plate shall adopt any dimensional shape, thickness, etc. according to the required characteristics of the structural member to which the fillet welded joint of the present invention is applied. Can do. For example, as the plate thickness of the upper plate and the lower plate, a plate thickness within a range of 0.8 mm to 35.0 mm can be adopted, but preferably 1 from the viewpoint of thinning (weight reduction) and strength of the joint. A plate thickness in the range of 0.0 mm to 25.0 mm, more preferably a plate thickness in the range of 1.0 mm to 4.0 mm, more preferably a plate thickness in the range of 1.0 mm to 3.5 mm. It is. The plate thickness may be the same or different between the upper plate and the lower plate.

  In the present invention, the upper plate and the lower plate are such that the end portion of the upper plate faces the upper surface of the inclined portion of the lower plate, and the angle α formed by the inclined portion of the upper plate and the inclined portion of the lower plate is It arrange | positions so that it may become a predetermined angle of 90 degrees or more, and between the edge part of this upper board and the upper surface of the inclination part of a lower board is joined by arc welding, and the above-mentioned welding part is formed.

[welded part]
In the fillet welded joint 1 according to the above-described embodiment, the welded portion 4 is welded between the end 2T of the upper plate 2 and the upper surface of the inclined portion 32 of the lower plate 3 as shown in FIG. The center 4C of the throat thickness 4D is lower than each of the plate thickness central axis 2a of the flat portion 21 of the upper plate 2 and the plate thickness central axis 3a of the flat portion 31 of the lower plate 3. It is formed so as to be located in D _2.
Here, in this specification, the “throat thickness” means the thickness of the portion where the distance from the root portion to the upper surface of the welded portion is the shortest in the cross section perpendicular to the weld line of the welded portion (so-called “actual” Throat thickness ").

In the fillet welded joint 1 of the present embodiment, the welded portion 4 is formed of a weld metal filled with a gap between the end 2T of the upper plate 2 and the upper surface of the inclined portion 32 of the lower plate 3. Yes. In the present invention, the welding method for forming the welded portion is not particularly limited, and any conventionally known welding method such as arc welding can be adopted.
Also, the welding conditions and the welding wire (welded metal) to be used are such that the center of the throat is located below the center thickness axis of the flat portion of the upper plate and the center thickness axis of the flat portion of the lower plate. Any welding conditions, welding wires, and the like that take into account the desired joint strength and the like can be employed as long as they can form a welded part. For example, as the shielding gas, any conventionally known shielding gas such as 100% CO ₂ gas, a mixed gas of Ar gas and 3% to 20% CO ₂ gas can be used, and other welding currents, Various welding conditions such as welding voltage, shield gas flow rate, welding speed, etc. are also arbitrary conditions considering the occurrence of defects such as undercut (for example, welding current: 180 A to 320 A, welding voltage: 15 V to 30 V, shield gas flow rate: 15 L / min to 30 L / min, welding speed: 30 cm / min to 150 cm / min, etc.) can be used. Furthermore, as the welding wire, for example, a solid wire for mild steel or high tension can be used.
In addition, regarding such welding conditions, when it is difficult to perform welding in one pass due to a large plate thickness, welding may be performed in a plurality of passes.
Further, the arc welding described above is not limited to gas shielded arc welding, and any arc welding method such as submerged arc welding can be employed.

  Furthermore, in this invention, it is preferable that the welding part has a peening process trace in a toe part, ie, the peening process is given to the toe part. When the peening process is performed on the toe portion of the welded portion, the fatigue strength of the toe portion becomes high, and fatigue cracks starting from the toe portion can be made less likely to occur.

  Such a peening process is not particularly limited, and any peening process such as a shot peening process, a hammer peening process, an ultrasonic peening process, or the like can be employed. In the present invention, when a predetermined fatigue strength is secured at the toe portion of the welded portion, such a peening process may not necessarily be performed.

  Further, in the present invention, the welded portion is formed so that the center of the throat thickness is located below the plate thickness central axis of the flat portion of the upper plate and the plate thickness central axis of the flat portion of the lower plate. If it is, other dimensional shapes, thicknesses, etc. will not be restrict | limited in particular, Arbitrary dimensional shapes, thicknesses, etc. according to desired joint intensity | strength etc. are employable.

(Another embodiment)
In the fillet welded joint 1 according to the above-described embodiment, the upper plate 2 and the lower plate 3 are, as shown in FIGS. 1 and 2, the plate thickness central axis 2a of the flat portion 21 in the upper plate 2, and Although the plate thickness central axis 3a of the flat portion 31 in the lower plate 3 is arranged on the same axis (that is, the plate thickness central axes 2a and 3a of the flat portions 21 and 31 coincide with each other), In the fillet welded joint of the present invention, the arrangement form of the upper plate and the lower plate is not limited to the arrangement form as in the above-described embodiment, and the plate thickness central axis of the flat portion in the upper plate and the flat plate in the lower plate The plate thickness central axis of the portion may not be on the same axis (that is, the plate thickness central axis of each flat portion may be shifted).

Here, FIG. 4 is a fillet welded joint 10 according to another embodiment of the present invention in which the arrangement form of the upper plate and the lower plate is different. In this other embodiment, since the configuration other than the configuration different from the above-described embodiment (that is, the axis deviation of the upper plate and the lower plate) is basically the same as the above-described embodiment, The detailed description is abbreviate | omitted.
As shown in FIG. 4, the fillet welded joint 10 according to another embodiment of the present invention includes a plate thickness central axis 2 a of the flat portion 21 in the upper plate 2 and a plate thickness central axis of the flat portion 31 in the lower plate 3. Although 3a and 3a are in a parallel positional relationship, they do not exist on the same axis and are shifted by a predetermined shift amount d (mm). The other configuration is the same as that of the fillet welded joint 1 of the above-described embodiment, and the upper plate 2 and the lower plate 3 are respectively flat portions 21 and 31 and the flat portions 21 and 31 to the lower side D ₂ . Inclined portions 22 and 32 extending to the end portions 2T and 3T while being inclined, and the end portion 2T of the upper plate 2 faces the upper surface of the inclined portion 32 of the lower plate 3 and the inclined portion 22 of the upper plate 2 The angle α formed by the inclined portion 32 of the lower plate 3 is arranged to be a predetermined angle of 90 ° or more, and the end portion 2T of the upper plate 2 and the upper surface of the inclined portion 32 of the lower plate 3 The center 4C of the throat thickness 4D of the welded portion 4 formed between is lower than the plate thickness central axis 2a of the flat portion 21 of the upper plate 2 and the plate thickness central axis 3a of the flat portion 31 of the lower plate 3. It is formed so as to be located in D _2.

Also in fillet welded joint 10 according to this alternative embodiment, the upper plate 2 and the lower plate 3, respectively a flat 21, 31, the end portion 2T while inclined lower side _{D 2} from the flat part 21 and 31 3T, and the end portion 2T of the upper plate 2 is disposed so as to face the upper surface of the inclined portion 32 of the lower plate 3, and the end portion 2T of the upper plate 2 The center 4C of the throat thickness 4D of the welded portion 4 formed between the upper surface of the inclined portion 32 of the lower plate 3 is the plate thickness central axis 2a of the flat portion 21 of the upper plate 2 and the flat portion 31 of the lower plate 3. since than each of the thickness center shaft 3a is formed so as to be positioned on the lower side D _2, when the applied load F _P tensile entire joint, the weld 4 is deformed to pushed out on the upper side D ₁ As a result, in the route portion 4R, the upper plate 2 and the lower plate 3 are formed in a direction in which they approach each other. Compressive stress fc to be used can be generated, and as a result, fatigue cracks starting from the root portion 4R are hardly generated.
Further, in this fillet welded joint 10, the angle α formed by the inclined portion 22 of the upper plate 2 and the inclined portion 32 of the lower plate 3 is arranged to be 90 ° or more. The rising angle of the end 4T becomes gentle, and the stress concentration on the toe 4T can be reduced.
Therefore, the fillet welded joint 10 according to this other embodiment also has less fatigue concentration starting from the root portion 4R while reducing the stress concentration on the toe portion 4T, and further improved fatigue. The characteristic can be exhibited.

In the present invention, the shift amount d (mm) between the plate thickness central axis of the flat portion of the upper plate and the plate thickness central axis of the flat portion of the lower plate is not particularly limited as long as the effect of the present invention is not impaired. For example, it is preferably in the range of greater than 0 mm and not greater than 10.0 mm, more preferably in the range of greater than 0 mm and not greater than 5.0 mm.
Further, in the present invention, the vertical positional relationship between the plate thickness central axis of the flat portion in the upper plate and the plate thickness central axis of the flat portion in the lower plate is not particularly limited as long as the effect of the present invention is not hindered. In this fillet welded joint, the plate thickness central axis of the flat portion of the lower plate may be above the plate thickness central axis of the flat portion of the upper plate.

(Production method)
Hereinafter, the manufacturing method of the fillet welded joint of the present invention will be described.
The method for manufacturing a fillet welded joint according to the present invention includes a step of forming an upper plate and a lower plate by forming an inclined portion in each of an upper plate forming plate member and a lower plate forming plate member having a flat structure (hereinafter, The end of the upper plate faces the upper surface of the inclined portion of the lower plate, and the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is 90 °. As described above, between the step of arranging the upper plate and the lower plate (hereinafter sometimes referred to as “second step”) and the upper surface of the upper plate end portion and the inclined portion of the lower plate. , Fillet welding so that the center of the throat is located below the center thickness axis of the flat portion of the upper plate and the center thickness axis of the flat portion of the lower plate (hereinafter referred to as “third step”). ").

  In the first step described above, by bending the vicinity of the end portion that becomes the welded portion of the upper plate forming plate member and the lower plate forming plate member having a flat structure such as a steel plate by any bending processing means, An upper plate and a lower plate having a flat portion and an inclined portion extending to the end while being inclined downward from the flat portion are produced. In the first step, the bending means and processing conditions used for bending the upper plate forming plate material and the lower plate forming plate material are not particularly limited as long as they do not impair the effects of the present invention. Arbitrary processing means and processing conditions in consideration of processing accuracy and the like can be adopted.

  Further, in the second step described above, the upper plate and the lower plate produced in the first step are arranged such that the end portion of the upper plate faces the upper surface of the inclined portion of the lower plate and the inclined portion and the lower plate of the upper plate. It arrange | positions so that the angle | corner made with an inclination part may become a predetermined angle of 90 degrees or more.

  In the third step, a welding wire such as a solid wire is used between the end of the upper plate and the upper surface of the inclined portion of the lower plate arranged in the second step under predetermined welding conditions. By performing fillet welding (for example, arc welding), the center of the throat is located below the center thickness axis of the flat portion of the upper plate and the center thickness axis of the flat portion of the lower plate. Forming part. In the third step, as described above, the welding conditions and the welding wire (welded metal) to be used are such that the center of the throat thickness is the central thickness axis of the flat portion of the upper plate and the central thickness axis of the flat portion of the lower plate. There is no particular limitation as long as the welded portion can be formed so as to be positioned below each of the above, and any welding condition, welding wire, or the like in consideration of desired joint strength or the like can be employed.

  Moreover, in the manufacturing method of this invention, you may have the surface modification process which performs a peening process with respect to the toe part of a welding part after the above-mentioned 3rd process. The peening treatment in the surface modification step is not particularly limited, and any peening treatment such as the above-described shot peening treatment can be adopted.

  In addition, the manufacturing method of the present invention is an arbitrary process before the first step, between each step of the first step to the third step and / or after the third step, within a range not impairing the effect of the present invention. You may have a process process (For example, the surface treatment process etc. of the board | plate material for upper board formation, and the board | plate material for lower board formation).

  According to the manufacturing method of the present invention, by including at least the above-described steps (that is, the first step to the third step), the fatigue crack starting from the root portion while reducing the stress concentration on the toe portion. It is possible to easily manufacture a fillet welded joint that is difficult to cause without requiring a difficult process (for example, a process that requires high positioning accuracy).

  The fillet welded joint of the present invention can be applied to various structural members such as parts of transportation equipment such as railway vehicles, structures of buildings, parts of various industrial machines, etc. in addition to undercarriage parts of automobiles. In particular, it can be suitably used for a structural member that is used in an environment where a repeated load such as vibration is applied. In addition, the fillet welded joint of the present invention is not limited to the above-described embodiments or examples to be described later, and can be appropriately combined, substituted, changed, and the like within the scope of the purpose and spirit of the present invention. Is possible. In this specification, ordinal numbers such as “first” and “second” are used to distinguish items with the ordinal numbers, and mean the order, priority, importance, etc. of each item. Not what you want.

  EXAMPLES Hereinafter, although an Example and a comparative example are illustrated and this invention is demonstrated more concretely, this invention is not limited only to such an Example.

Example 1
First, a hot rolled steel sheet having a plate thickness of 2.9 mm and a tensile strength of 481 MPa is prepared as an upper plate forming plate material, and a flat plate is formed by bending a position 20 mm from the end of the hot rolled steel sheet at an inclination angle of 45 °. The upper board which has a part and an inclination part was produced. Similarly, by preparing a hot rolled steel sheet having a plate thickness of 2.9 mm and a tensile strength of 481 MPa as a lower plate forming plate material, by bending a position of 17 mm from the end of the hot rolled steel sheet at an inclination angle of 45 °, A lower plate having a flat portion and an inclined portion was produced.
The prepared upper and lower plates are arranged so that the end of the upper plate faces the upper surface of the inclined portion of the lower plate and the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is 90 °. And predetermined welding conditions (welding current: 235 A, welding speed 80 cm / min, welding wire: solid wire for mild steel equivalent to JIS 3312 YGW16) between the end portion of the upper plate and the upper surface of the inclined portion of the lower plate. In this case, arc welding is performed so that the center of the throat thickness is located below the center thickness axis of the flat portion of the upper plate and the center thickness axis of the flat portion of the lower plate. A fillet weld joint of Example 1 having a weld structure substantially similar to that of the meat weld joint 1 was obtained.

Comparative Example 1
As the upper plate and the lower plate, hot-rolled steel plates each having a thickness of 2.9 mm and a tensile strength of 481 MPa (that is, an upper plate and a lower plate having only a flat portion and no inclined portion) are prepared. After the upper plate and the lower plate are placed one above the other, the end portion of the upper plate is arc welded under the same welding conditions as in Example 1 above, so that the fillet welded joint shown in FIG. A fillet welded joint of Comparative Example 1 having a structure substantially the same as 1 ′ was obtained.

The fillet welded joints of Example 1 and Comparative Example 1 thus obtained were each cut into strips to form test pieces, and then tensile fatigue tests (axial load, stress ratio: 0) of each test piece. .1 (tension-tensile condition), repetition frequency: 10 Hz), and each fatigue limit ratio (ratio of fatigue limit (σ _W ) to tensile strength (σ _B ) (σ _W / σ _B )) and route The presence or absence of cracks in the part was confirmed. The results of this tensile fatigue test are as shown in Table 1 below.

  As shown in Table 1, the fillet welded joint of Example 1 has a higher fatigue limit ratio than the fillet welded joint of Comparative Example 1, and the occurrence of cracks in the root portion cannot be confirmed. It was found to have excellent fatigue properties.

DESCRIPTION OF SYMBOLS 1 Fillet welded joint 2 Upper plate 21 Flat portion of upper plate 22 Inclined portion of upper plate 2T End portion of upper plate 2a Thickness central axis of flat portion of upper plate 2b Thickness central axis of inclined portion of upper plate 3 Lower Plate 31 Flat portion of lower plate 32 Inclined portion of lower plate 3T End portion of lower plate 3a Thickness central axis of flat portion of lower plate 3b Thickness central axis of inclined portion of lower plate 4 Welded portion 4R Route portion 4T Toe 4D throat thickness 4C throat thickness center

Claims (3)

A fillet welded joint composed of two metal plates, an upper plate and a lower plate,
Each of the upper plate and the lower plate includes a flat portion and an inclined portion extending to the end while inclining downward from the flat portion, and an end portion of the upper plate is an inclined portion of the lower plate. It is disposed so as to face the upper surface and the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is 90 ° or more,
The center of the throat thickness of the welded portion formed between the end portion of the upper plate and the upper surface of the inclined portion of the lower plate is the thickness axis of the flat portion of the upper plate and the flat portion of the lower plate. The fillet welded joint formed so as to be positioned below each of the plate thickness central axes.   The fillet welded joint according to claim 1, wherein the weld has a peening mark on the toe. A method for producing a fillet welded joint according to claim 1 or 2,
Forming the inclined portion on each of the upper plate forming plate member and the lower plate forming plate member having a flat structure, and producing the upper plate and the lower plate;
The upper plate and the upper plate so that the end portion of the upper plate faces the upper surface of the inclined portion of the lower plate and the angle formed by the inclined portion of the upper plate and the inclined portion of the lower plate is 90 ° or more. Arranging the lower plate;
Between the end of the upper plate and the upper surface of the inclined portion of the lower plate, the center of the throat is the plate thickness central axis of the flat portion of the upper plate and the plate thickness central axis of the flat portion of the lower plate. Filling the fillet so as to be located below each of them,
The manufacturing method of the said fillet weld joint.

Images