JP2001115478A - Working arm structure of working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working arm structure of a working machine which can mount a connection bracket which is welded to an end part of the working arm formed on a box-shaped section of plate members by stabilizing the welding quality without being affected by the fluctuation, etc., in dimension of the plate members, and by reducing the fluctuation in dimension caused by the thermal strain during the welding. SOLUTION: The connection bracket 20 comprises a base part 21 integratedly joined with each of plate members 12, 14, 16 and 18 between end portions of a pair of plate members facing each other of a box-shaped section of a working arm 6, and bracket parts 22a and 22b integratedly joined with the base part. The base part is formed cylindrical, and the plate members are abutted on an outer circumferential part of the cylinder. The bracket parts are mounted on both ends in the axial direction of the cylindrical base part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working arm structure of a working machine, and more particularly to a working arm structure suitably used for a working arm of a working machine such as a boom of a hydraulic shovel.

[0002]

2. Description of the Related Art Working machines such as construction machines and cargo handling machines are:
It has one or a plurality of long working arms to which a working tool or the like is attached. For example, a hydraulic shovel, which is a typical working machine, is a boom that is a working arm that is vertically swingably attached to a body of a machine body, and a working arm that is vertically swingably attached to a tip of the boom. Arm. A bucket, which is a working tool, is attached to the tip of the arm so as to be vertically swingable.

Since these working arms are formed to be long, they have a sufficient strength against bending, twisting and the like, and are formed in a box-shaped structure by plate members so as to reduce the weight. ing.

[0004] Referring to Fig. 7, the working arm will be described by taking the above-mentioned boom as an example. The boom generally designated by the reference numeral 50 is formed in a box-shaped structure by welding various steel members to each other. . That is, the boom 50 is formed into a box-shaped structure having a rectangular box-shaped cross-section and extending in the longitudinal direction by the upper plate 52, the lower plate 54, the left side plate 56, and the right side plate 58, which are plate members extending in the longitudinal direction. Have been. At one end in the longitudinal direction of the box-shaped structure, a connection bracket 60 provided with a bearing hole 60b for connecting to the arm, and at the other end, a connection bracket 62 provided with a bearing hole for connecting to the body of the machine are integrally formed. It is attached.

The bearing bracket 60 is formed in a forked shape by casting, forging, or a combination of steel members. A bearing hole 60b is formed in each of the forked portions on an axis 60a orthogonal to the longitudinal direction of the boom 50. ing. The bearing bracket 60 includes an upper plate 52, a lower plate 54, a left side plate 56,
And it is butted and welded and joined to each end of the right side plate 58. The position of the bearing hole 60b of the bearing bracket 60 in the longitudinal direction of the boom 50 is important for the function as a working arm. In welding and joining, the position of the bearing hole 60b is related to the connection bracket 62 at the other end by a jig or the like. The length L is defined as follows.

[0006]

The working arm structure of the conventional working machine of the above-described embodiment has the following problems to be solved.

(1) Quality of welded portion: butt welding direction of butt welding of the bearing bracket 60 attached to the end of the working arm in the above-described manner with each end of the plate member forming the box-shaped cross section. In the bearing bracket 60
Is defined by the dimension L, the position is changed by errors and variations in manufacturing dimensions and mounting dimensions of the respective plate members (the upper plate 52, the lower plate 54, the left side plate 56, and the right side plate 58). Cheap. When these long plates are divided into a plurality of plates and joined, the fluctuation becomes even greater. Therefore, it is difficult to stabilize the quality of the butt weld.

(2) Dimensional accuracy of the bearing bracket: When the welding gap at the butt weld changes, the amount of molten metal at the weld changes accordingly, and the dimensional change of the bearing hole 60b and the bearing hole due to thermal distortion of welding. A shift or the like of the 60b on the axis 60a occurs. Also, since the fluctuation range of the thermal strain increases,
It is difficult to predict the amount of variation, and it is difficult to properly maintain dimensional accuracy.

The present invention has been made in view of the above-mentioned circumstances, and a technical problem of the present invention is to provide a connecting bracket which is welded and attached to an end of a working arm formed into a box-shaped cross section by a plate member, and has a dimension of the plate member. It is an object of the present invention to provide a working arm structure of a working machine that can stabilize the quality of welding without being affected by fluctuations in welding, and can be mounted with less dimensional fluctuation due to thermal distortion of welding.

[0010]

According to the present invention, as a working arm structure for solving the above technical problem, a longitudinally extending working arm formed by a plate member and having a box-shaped cross section is provided. A connection bracket welded and attached to the portion, a base portion sandwiched between ends of a pair of opposed plate members of the box-shaped cross section and integrally joined to each of the plate members,
A working arm structure of a working machine, characterized by being formed by a bracket part integrally joined to the base part.

By connecting the base of the connecting bracket to each of the plate members sandwiched between the pair of plate members,
Even if the relative position of the work arm between the plate member and the base in the longitudinal direction fluctuates, the condition of the welded portion between the plate member and the base is not changed, thereby stabilizing the quality of welding and reducing the fluctuation of thermal distortion. .

In a preferred embodiment, the base is formed in a cylindrical shape, and the plate member is in contact with an outer peripheral portion of the cylinder.

Then, the plate member is brought into contact with the outer peripheral portion of the cylinder to form a stable welded portion.

In a preferred embodiment, the bracket is attached to both ends in the axial direction of the cylindrical base.

Then, the brackets are attached to both ends of the cylindrical base to form a forked connecting bracket.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A working arm structure of a working machine constructed according to the present invention will be described below with reference to the accompanying drawings, which show a preferred embodiment of a boom of a hydraulic shovel as a typical working machine. This will be described in more detail.

Referring to FIG.
A hydraulic excavator indicated by a boom 6 is a boom 6 which is a working arm attached to the body 4 so as to be vertically swingable, and a boom 6
Arm 8 which is a working arm attached to the tip of the robot so as to be vertically swingable. A bucket 10 as a working tool is attached to the tip of the arm 8 so as to be vertically swingable.

Referring to FIG. 2 together with FIG. 1,
The boom 6 is formed in a box-shaped structure by welding various steel members to each other. That is, the boom 6 is a plate member extending in the longitudinal direction, the upper plate 12, the lower plate 14,
The left side plate 16 and the right side plate 18 form a box-shaped structure having a rectangular box-shaped cross section. A connecting bracket 20 having a bearing hole for connecting to the arm 8 at one end in the longitudinal direction, and a connecting bracket 2 having a bearing hole for connecting to the body 4 at the other end.
2 are attached respectively.

Referring to FIGS. 3 to 5 together with FIG. 2, the connecting bracket 20 includes a base 21 and a pair of brackets 22a and 22 integrally joined to the base 21.
b. The base 21 is joined to ends of an upper plate 12 and a lower plate 14, which are a pair of plate members facing each other in a box-shaped cross section. Bracket parts 22a and 22b
Are formed with bearing holes 20b on the same axis 20a.

The base 21 has a cylindrical shape extending in a direction perpendicular to the longitudinal direction of the boom 6, and is formed by a pipe member or casting. The outer diameter of the cylinder is formed so as to abut between the ends of the upper plate 12 and the lower plate 14. The length of the cylinder is the upper plate 12
And the width of the lower plate 14 is substantially the same as the width of the band.

The pair of bracket portions 22a and 22b are
It is formed in a plate shape by forging or casting.
The bracket portions 22a and 22b are substantially the same in the present embodiment. An annular protruding portion 22c for joining with the base 21 is formed on one plate-like surface of the bracket portions 22a and 22b. Projection 22c
Are formed so as to protrude smoothly from the plate-like surface of each of the bracket portions 22a and 22b.

The base 21 and the brackets 22a and 22b formed as described above have both ends of the base 21 and the protruding portions 22c of the brackets 22a and 22b butted against each other, as shown in FIG. It is welded by deep and deep welding or by groove welding with a groove. Bracket portions 22a and 22
In each of b, a bearing hole 20b is machined and formed along the same axis 20a in this welded state, and the connection bracket 20 is completed.

The connecting bracket 20 has its base 21 sandwiched between the ends of the upper plate 12 and the lower plate 14 as shown in FIG. 5, and the bearing hole 20a is positioned at the other end as shown in FIG. The dimension from the connection bracket 22 is positioned at the position of the length L, and the upper plate 12 and the lower plate 14
Is welded to the upper plate 12 and the lower plate 14 in the thickness direction by deep and depth welding such as laser welding. The base 21 and the upper plate 12 and the lower plate 14 are completely joined by this welding. However, if further strength is required, the outer periphery of the base 21 and the distal end of the upper plate 12 and the lower plate 14 may be connected. (Indicated by Y in FIG. 5). In addition,
The bracket portions 22a and 22b are appropriately welded to the upper plate 12, the lower plate 14, the left side plate 16 and the right side plate 18 by relatively small fillet welding to join the connection bracket 20 at the end of the boom 6. The shape of the part is adjusted.

The operation of the working arm structure of the working machine as described above will be described with reference to FIG.

(1) Quality of welded portion: bracket portion 22a
And the base 21 joined with the base plate 22b are sandwiched between the upper plate 12 and the lower plate 14 of the boom 6 by abutting the cylindrical outer peripheral portion thereof. Therefore, even if these relative positions change in the longitudinal direction (the direction indicated by X), a stable welded portion is formed. Therefore, even if errors and variations occur in the manufacturing dimensions and mounting dimensions of each plate, the welded joint between the base 21 and the upper plate 12 and the lower plate 14 is stable, and stable quality welding is ensured. Is done. Further, since the base 21 is joined to the protruding portion 22c of the bracket portions 22a and 22b which rises smoothly, the base 21 and the bracket portions 22a and 22b are firmly and integrally joined.

(2) Dimensional accuracy of bearing bracket: base 21 to which brackets 22a and 22b are attached;
Upper plate 12, Lower plate 14, Left side plate 1
6, and the welding to the right side plate 18 and the like become stable, so that the dimensions of the bearing hole 20b and the axis 20a
Variations due to thermal distortion, such as the above displacement, are reduced. Therefore, repair work such as machining after welding and joining is also easy or unnecessary.

As described above, the present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above-described embodiments, and can be variously modified or modified within the scope of the present invention. It is.

(1) Base Shape: In the embodiment of the present invention, the base 21 of the connecting bracket 20 is formed in a cylindrical shape, but as shown in FIG. You may make it small and make it elliptical shape. By making the base 21 have an elliptical cylindrical shape, the amount of protrusion of the bracket portions 22a and 22b from the base 21 can be reduced. The sectional shape of the base 21 is not limited to a perfect circle or an ellipse, but may be a polygon such as a quadrangle.

(2) Bracket portion: In the embodiment of the present invention, the connecting bracket 20 is provided with bracket portions 22a and 22b at both ends of the base portion 21 and is formed in a forked shape. It is not limited, and can be provided in an appropriate position and in an appropriate form, such as provided only at the center of the base 21 in the middle in the axial direction.

[0030]

According to the working arm structure of the working machine constructed in accordance with the present invention, the connecting bracket, which is welded and attached to the end of the working arm formed into a box-shaped cross section by the plate member, is provided with the size of the plate member. A work arm structure of a work machine is provided which is not affected by fluctuations and the like, stabilizes welding quality, and can be mounted with reduced dimensional fluctuations due to thermal distortion of welding.

[Brief description of the drawings]

FIG. 1 is a side view of a hydraulic excavator which is a typical work machine having a work arm structure of a work machine configured according to the present invention.

FIG. 2 is a perspective view of one boom of a working arm of the excavator shown in FIG.

FIG. 3 is a perspective view showing a part of a connection bracket of the boom shown in FIG.

FIG. 4 is a cross-sectional view showing a joint between a bracket and a base of the connection bracket shown in FIG. 3;

FIG. 5 is a side view showing a joint between the base of the connection bracket shown in FIG. 3 and an upper plate and a lower plate, with one of the brackets being removed;

FIG. 6 is a perspective view of another embodiment of the base of the connection bracket.

FIG. 7 is a perspective view of a conventional boom.

[Explanation of symbols]

 2: hydraulic excavator (work machine) 4: body body 6: boom (work arm) 8: arm (work arm) 12: upper plate (plate member) 14: lower plate (plate member) 16: left side plate (plate member) 18: Right side plate (plate member) 20: Connection bracket 20b: Bearing hole 21: Base 22a: Bracket part 22b: Bracket part 22c: Projection part 50: Boom (work arm) 60: Connection bracket

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaya Yoto 4-10-1, Yoga, Setagaya-ku, Tokyo Inside New Caterpillar Mitsubishi Corporation (72) Inventor Kunitomo Shimizu 4-1-1, Yoga, Setagaya-ku, Tokyo No. Caterpillar Mitsubishi Corporation (72) Inventor Kazuaki Kinoshita 4-10-1, Yoga, Setagaya-ku, Tokyo (72) Inventor Fumihiro Nishimura 4--10 Yoga, Setagaya-ku, Tokyo No. 1 Inside New Caterpillar Mitsubishi Corporation (72) Inventor Norihisa Manami 4-1-1 Yoga, Setagaya-ku, Tokyo (72) Inventor Morio Murakami 4-chome Yoga, Setagaya-ku, Tokyo No. 10-1 New Caterpillar Mitsubishi Corporation (72) Inventor Yoshiaki Harada 4-10-1, Yoga, Setagaya-ku, Tokyo Pillar Mitsubishi within Co., Ltd.

Claims (3)

[Claims] A working bracket formed by a plate member and having a box-shaped cross section and extending in a longitudinal direction is provided with a connecting bracket welded and attached to an end in the longitudinal direction of the work arm. A working arm of a working machine, formed by a base portion which is sandwiched between ends of the base member and integrally joined to each of the plate members, and a bracket portion which is integrally joined to the base portion. Construction. 2. The working arm structure of a working machine according to claim 1, wherein said base is formed in a cylindrical shape, and said plate member is in contact with an outer peripheral portion of said cylinder. 3. The working arm structure of a working machine according to claim 2, wherein said bracket portion is attached to both ends in the axial direction of said cylindrical base portion.