JP2950768B2 - Support arm structure of working device in construction machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of construction machines such as hydraulic shovels used for various construction works and civil works.

[0002]

2. Description of the Related Art In general, in such construction machines, a working device such as a blade is swingably supported via a pair of left and right support arms, and the working device is swung by a telescopic operation of a hydraulic cylinder. There is one configured.
By the way, the hydraulic cylinder has one end connected to the machine body and the other end connected to a support arm via a bracket or the like. In this case, when the working device is a blade, for example, When performing work such as lifting the aircraft by applying thrust to the hydraulic cylinder without evenly contacting the ground, a large load is applied to the support arm in a left-right imbalanced state and a large torsional moment is generated However, this causes a large stress to act on the cylinder mounting portion of the support arm. For this reason, the support arm must have a high strength to cope with the large stress, but the support arm is generally in the shape of a rectangular tube, and in order to increase the strength, a solid Or whether the cross section is large even if it is hollow. However, in this case, the weight and size of the support arm are significantly increased. Hinders cost reduction and is difficult to adopt.

[0003]

Conventionally, as shown in FIG. 4, the strength of the support arm 5 is increased by connecting the cylinder mounting portions of the left and right support arms 5 with a reinforcing member 15 such as a pipe. Was. However, in this case, when the torsional moment is generated, there is a problem that stress tends to concentrate on a connecting portion between the support arm 5 and the reinforcing member 15. On the other hand, it is conceivable to increase the strength of the cylinder mounting portion of the support arm by increasing the length of the support arm mounting surface of the cylinder mounting bracket. However, in this case, since the stress mainly acts on both ends of the mounting surface of the support arm of the bracket, there is a problem that even if the mounting surface is lengthened, only the portion where the stress acts is shifted, and the fundamental solution is not solved.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention has been made with the object of solving these problems. In a construction machine configured to movably support and swing the working device by extension and contraction operation of a cylinder having one end attached to the support arm, the support arm may be provided over substantially the entire surface of the cylinder mounting surface. This is a hollow rectangular tube having a large thickness. By doing so, the strength of the support arm can be increased without greatly increasing the weight and size of the support arm, and a large load acts on the support arm in a left-right imbalanced state and a large torsional moment is generated. Even in the case where it occurs, it is advantageous in terms of strength. . In this case, the support arm can be made thicker by welding a reinforcing plate to one surface of the hollow rectangular tube material or by welding a thick plate to the opening surface of the C-shaped channel material.

[0005]

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a hydraulic excavator, which is a crawler-type lower traveling body 2, an upper revolving body 3 rotatably supported above the lower traveling body 2, and an upper revolving body 3 And the like are the same as those of the related art in which the front attachment 4 and the like are attached to the front part of the vehicle.

Reference numeral 5 denotes a pair of left and right support arms which are supported on the car body 6 of the lower traveling body 2 via support brackets 7 so as to be able to swing up and down. Are integrally attached. Reference numeral 9 denotes a hydraulic cylinder having a base end of the cylinder cylinder 9a connected to the support bracket 7 and a distal end of the piston rod 9b connected to the support arm 5 side. The blade 8 swings up and down with the swinging of the blade 5 up and down.

The support arm 5 is formed of a hollow rectangular tube-shaped molding material. A reinforcement plate 10 is welded to the upper surface 5a of the support arm 5 over substantially the entire surface. Thereby, the upper surface portion 5a is in a state of being reinforced with a greater thickness than other surface portions. A mounting bracket 11 for supporting the piston rod 9b of the hydraulic cylinder 9 is fixed to the upper surface of the reinforcing plate 10 by welding or the like.

In the structure described above, the tip of a hydraulic cylinder 9 that expands and contracts to swing the blade 8 up and down is attached to the upper surface 5a of the support arm 5 that supports the blade 8. The upper surface portion 5a is formed to be thick and reinforced by a reinforcing plate 10 welded over the entire surface.

As a result, the strength of the support arm 5 can be increased without significantly increasing the weight and size of the support arm 5, but the thickness of the entire upper surface 5a of the support arm 5 is increased. When a large torsion moment is generated due to a large load acting on the support arm 5 in a left-right imbalanced state, the conventional left and right support arms are connected by a reinforcing member such as a pipe. Therefore, stress is not concentrated on the connecting portion, which is advantageous in terms of strength. In addition, the strength of the support arm 5 can be easily adjusted by appropriately changing the thickness of the auxiliary plate 10 even when the support arm 5 is formed by using a hollow rectangular tube having the same size. In forming the various supporting arms 5 to be provided, the members can be shared, which can contribute to cost reduction. In addition, since the welding portion between the upper surface portion 5a and the auxiliary plate 10 is linear, there is an advantage that the welding process can be made robotic and the welding quality can be improved.

In the above-described embodiment, the upper surface 5a is made thicker by using the reinforcing plate 10. However, as in the second embodiment shown in FIG. To a C-shaped channel material 12 having an open side.
In addition, a thick plate 13 may be welded to the opening side of the channel member 12 and the thick plate 13 may be used as the upper surface. In this case, as in the third embodiment shown in FIG. 3 (C), the plate 13 has a plurality of (or one) ridges 13a formed on one side, and The plate member 13 can be welded to the channel member 12 so that the ridge 13a is hidden in the opening. In this way, even if the plate member 13 having the same thickness is used. Thus, the strength of the support arm can be further increased. Further, in the case of a single ridge 13a, a T-shaped steel can be used as in the fourth embodiment shown in FIG. Furthermore, as in the fifth embodiment shown in FIG. 3E, a molding material 14 whose upper surface portion 14a is set to be thicker than other surface portions can be used. In this case,
There is an advantage that welding is not required.

[Brief description of the drawings]

FIG. 1 is a side view of a hydraulic excavator.

FIG. 2 is a perspective view of a support arm unit.

3A is a cross-sectional view of the support arm according to the first embodiment, FIG. 3B is a cross-sectional view of the support arm according to the second embodiment, FIG. 3C is a cross-sectional view of the support arm according to the third embodiment, (D) is a sectional view of the support arm according to the fourth embodiment, and (E) is a sectional view of the support arm according to the fifth embodiment.

FIG. 4 is a perspective view of a support arm portion showing a conventional example.

[Explanation of symbols]

 Reference Signs List 5 Support arm 8 Blade 9 Hydraulic cylinder 10 Reinforcement plate 12 C-type channel material 13 Plate material

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Ichisa Iwasa 4-1-1 Yoga, Setagaya-ku, Tokyo New Inside Caterpillar Mitsubishi Corporation (72) Inventor Shigeyoshi Adachi 4-1-1 Yoga, Setagaya-ku, Tokyo New Caterpillar Mitsubishi Corporation (58) Fields surveyed (Int. Cl. ⁶ , DB name) E02F 3/815 E02F 3/38

Claims (2)

(57) [Claims] 1. A construction wherein a working device is swingably supported on a body side via a support arm, and one end of the working device is swung by a telescopic operation of a cylinder attached to the support arm. A support arm structure for a working device in a construction machine, wherein the support arm has a hollow rectangular cylindrical shape in which a cylinder mounting surface portion is formed to be thick over substantially the entire surface. 2. The cylinder mounting surface according to claim 1, wherein the support arm is formed by welding a reinforcing plate to one surface of the hollow rectangular tube material or welding a thick plate to the opening surface of the C-shaped channel material. Support arm structure for working equipment in thickened construction machinery.