JPH11254178A - Structure for providing welding strength - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for avoiding generation of stress concentration and also for increasing absolute welding strength. SOLUTION: In a structure provided with a first member 3 having a plane and with a second member 21 which is welded to the first member, the second member 21 has at least two faces orthogonally crossing the plane of the first member 3, each of these two faces is bent in the direction not in contact with each other at the end welded to the first member 3 to form contact surfaces with the first member 3, at least one side or more of each contact surface are welded to the plane of the first member 3, and a notched part 24 is formed near the intersection of the two faces of the second member 21 and the joined area to the plane of the first member 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welded structure in which strength is required for a welded joint.

[0002]

2. Description of the Related Art For example, an upper frame 2 of a hydraulic excavator 1 shown in FIGS. 3 and 4 has a boom bracket 4 formed by a pair of plate members 3 facing each other in parallel and standing upright. By inserting a pin 6 into a pin hole 5 provided in the boom bracket 4 and a pin hole (not shown) provided in a lower end portion of the boom 7, the boom 7 can swing up and down with respect to the upper frame 2. And On the left and right sides of the boom bracket 4, mounting spaces for various devices (not shown) called side decks 8 are connected. In addition to the normal vertical (front-rear) force on the boom 7, a left-right force may be applied depending on the working condition, and this force acts on the boom bracket 4 as a torsional force. In addition, since a heavy object is mounted on the left and right side decks 8 and the hydraulic excavator 1 itself is exposed to severe vibrations and shocks, the left and right sides of the boom brackets 4 supporting the side decks 8 in a cantilever state. A force acts on each of the plate members 3 and 3 in a direction in which the plate members are pushed and opened. The boom bracket 4 needs to resist these forces.

[0003] For this reason, 2 which constitutes the boom bracket 4
The plate members are usually connected by a plurality of connecting members 9, 10, 11 to maintain strength. However, a high stress is generated due to the above-mentioned force acting on the connecting member. In particular, the connecting member has an L-shaped or U-shaped cross section (corresponding to the connecting member 10 in the figure). In many cases, stress concentration occurs in the connecting member 10 at a portion where the two surfaces forming the L-shape or the U-shape intersect with the plate material 3 (schematically shown in FIG. 5).

In order to avoid the stress concentration, for example, means as disclosed in Japanese Utility Model Registration No. 2544441 is considered. According to the present invention shown in FIG. 6, a small width first notch 11 is provided in a portion of the connecting member 10 '(second member) where stress concentration occurs, and a concave notch is provided adjacent to the first notch 11. The second notch 12 is provided to form a contact portion with the plate 3 (first member) on the protruding piece 13, and the position of the toe of the welding bead 14 is 5 m from the end of the protruding piece 13.
m or more and within the depth of the second notch 12. According to this, the occurrence of stress concentration is suppressed, and the welding legs are not lengthened, the plate pressure is not increased, and the reinforcing plate is not required. No effect is produced.

[0005]

However, according to the configuration of Japanese Utility Model Registration No. 2544441, the contact portion between the plate member 3 (boom bracket 4) and the connecting member 10 'is inevitably reduced, and welding is not performed. Since the bead 14 is also shortened, there is a problem that the absolute connection strength is reduced. An object of the present invention is to provide a welded structure capable of preventing stress concentration and increasing the absolute connection strength.

[0006]

According to the present invention, there is provided a structure having a first member having a flat surface and a second member welded to the first member. Has at least two surfaces orthogonal to the plane of the first member, and each of the surfaces is bent in a direction in which they do not come into contact with each other at an end that is welded to the first member. A contact surface for the member is formed, and at least one or more of the end sides of the contact surface is welded to the plane of the first member, and the surfaces of the second member are connected to each other. A notch was formed near the intersection of the first member with the plane.

As a result, it is possible to suppress the occurrence of stress concentration and to obtain a strong welding connection state capable of withstanding high stress.

[0008]

FIG. 1 shows a portion corresponding to FIG. 5, which is a conventional technique, when the present invention is applied to an upper frame 2 of a hydraulic excavator 1 shown in FIGS. 3 and 4, for example. 1 are substantially the same as those in the conventional technology, and therefore, the same reference numerals as those in the conventional technology are used. In the drawing, reference numeral 3 denotes a plate member constituting the boom bracket 4 described above, and corresponds to the first member of the first aspect. Reference numeral 21 denotes a connecting member as a second member, which is formed in an L-shaped cross section.
Reference numerals 22 and 23 denote bent portions whose back surfaces serve as contact surfaces with the plate material 3, 24 denotes notched portions, 25 denotes an upper surface of the connecting member 21,
Is a rear surface of the connecting member 21, and 14 'is a welding bead.

Next, the structure and operation of the present invention will be described with reference to FIG. Although both ends of the connecting member 21 are welded to the pair of plate members 3 forming the boom bracket 4 in substantially the same manner, only one side will be described here.
The connecting member 21 is formed by bending a plate member to form an upper surface 25 and a rear surface 26. Although not shown, a hydraulic switching valve for switching the supply of pressure oil to various hydraulic actuators mounted on a hydraulic excavator may be mounted on the upper surface 25 in some cases. The upper surface 25 and the rear surface 26 are bent upward and rearward at ends connected to the plate member 3 in a direction perpendicular to the respective surfaces to form bent portions 22 and 23 having a contact surface on the back surface. That is, after forming the bent parts 22 and 23 by bending,
The connecting member 21 is arranged at a predetermined portion of the plate 3, and the connecting member 21 is fixed to the plate 3 by welding the outer periphery of the bent portions 22 and 23. In FIG. 1, the weld bead 14 ′ is welded on two sides of each bent portion, and the weld bead 14 ′ is provided. However, the welded side is not limited to this, and the stress generated in this portion is not limited to this. Depending on the size of each one side only, or 3
All sides (three sides excluding a part continuous with the upper surface 25 or the rear surface 26) may be welded, but it is preferable to weld two or more sides each.

As in the prior art, the side decks 8, 8 are fixed to the plate 3 constituting the boom bracket 4 by welding or the like, and the plate 3 is attached to the side deck 8 and a driver's cab mounted on the side deck. And various devices such as hydraulic devices are supported in a cantilever state. For this reason, the plate members 3 are always in a state where a load is applied outward.
Further, since the vibration of the hydraulic excavator itself, the impact during traveling and work, and the like act, the load in the direction in which the plate members 3 and 3 are opened outward becomes an impact load, which further increases. Also, when excavating with an arm and a bucket connected to the end of the boom 7, excavation is performed while pressing the side surface of the bucket against the wall of the excavated groove. Also when performing dismantling work, a load in the lateral direction acts on the arm and the boom, so that a force in the torsion direction acts on the boom bracket 4.

However, according to the present invention, the contact between the first member (the plate member 3) and the second member (the connecting member 21) is smaller than the butt welding as in the conventional technique shown in FIG. The surface becomes large, and the entire length of the weld bead 14 'can be lengthened, so that a strong weld connection can be made. Therefore, the boom bracket does not deform even under the above-mentioned load condition. Also, the connecting member 21
A notch 24 is formed at a portion where the upper surface 25, the rear surface 26 and the plate material 3 intersect with each other, and the notch 24 for dispersing stress is formed at this portion where stress concentration is most likely to occur. The occurrence of cracks or the like due to stress concentration in the connecting member 21 can be suppressed.

FIG. 2 is a view showing the connecting member 21 in a state before the bending portions 22 and 23 are bent. The connecting member 21 is provided by processing a notch 24 in a single steel plate, and is further bent in parallel with the longitudinal direction. At this time, the notch 24 is a corner X formed by bending.
On -X. Thereafter, bending is performed at 27 and 28 indicated by broken lines, respectively, to form bent portions 22 and 23. That is, the above-described effects of the present invention can be produced only by processing a single member, so that it is not necessary to add a reinforcing member, and an increase in the number of parts can be prevented.

Although only the boom bracket portion of the hydraulic excavator has been described here, the application of the present invention is not limited to this. In particular, a member having an L-shaped cross section or a concave shape is attached to a conventional flat plate. It is needless to say that a stronger welded structure can be obtained by applying the method to the part that has been welded together.

[0014]

According to the present invention, particularly when a welded structure is formed by welding a member having an L-shaped cross section or a concave shape to a steel plate having a flat surface to form a welded structure, stress concentration can be reduced without adding a reinforcing member or the like. Generation can be suppressed, and a strong welding connection state that can withstand high stress can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic enlarged view of an essential part showing an embodiment of the present invention.

FIG. 2 is a view showing a connecting member before bending a bending portion.

FIG. 3 is a diagram showing a hydraulic excavator to which the present invention can be applied.

FIG. 4 is a view showing a conventional upper frame of the hydraulic excavator shown in FIG.

FIG. 5 is a schematic enlarged view of a main part showing a part A of FIG. 3;

FIG. 6 is a schematic enlarged view of a main part showing a configuration of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic excavator 2 Upper frame 3 Plate material 4 Boom bracket 7 Boom 8 Side deck 9, 10, 10 ', 11, 21 Connection member 22, 23 Bending part 24 Notch part

Claims (1)

[Claims] 1. A structure having a first member having a plane and a second member welded to the first member, wherein the second member is formed on a plane of the first member. At least two surfaces orthogonal to each other, wherein each of the surfaces is bent in a direction in which they do not come into contact with each other at an end portion that is welded to the first member to form a contact surface with the first member; A portion where at least two sides or more of the end sides of each contact surface are welded to the plane of the first member, and where the respective surfaces of the second member intersect with the plane of the first member. A weld strength structure having a notch formed in the vicinity.