JP2003003512A - Upper boom for construction machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an upper boom for use in a front working mechanism of construction machinery, which simplifies installation of a bracket for mounting a cylinder, and increases installation strength of the bracket and strength of the upper boom against torsion, etc. SOLUTION: The paired brackets 24 and 25 are provided on a side surface of the upper boom 20; a lower plate 30, which forms the upper boom 20, is partially extended out in a direction of the side surface of the upper boom 20, so that the first bracket 24 can be formed in such a manner as to be integral with the lower plate 30; and a reinforcing bulkhead 26 inside the upper boom 20 is provided in an area of the installation of the bracket 24 in a direction orthogonal to an axis of the upper boom 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction machine upper boom, and more particularly, to a front work mechanism of a construction machine. The present invention relates to a structure of an upper boom that is connected between a lower boom that extends from a main body of a construction machine and an arm that has a front attachment such as a bucket attached to a tip of the boom divided into two.

[0002]

2. Description of the Related Art FIG. 4 shows a hydraulic excavator as an example of a construction machine. This hydraulic excavator includes a lower traveling body 1 having a pair of crawler type traveling units 1a on the left and right, and an upper revolving body 2 installed on the lower traveling body 1 via a revolving device.
And a front working mechanism 3 extending forward from the upper swing body 2. The upper slewing body 2 has a cab 4
Is formed, and the operator is boarded and operated in the operator's cab 4 to perform work such as excavation of earth and sand by the front work mechanism 3.

The front working mechanism 3 is suitable for performing work such as digging a gutter, and for this reason, the boom connected to the upper revolving superstructure 2 has a base end portion which can be elevated to the upper revolving superstructure 2. The lower boom 5 thus connected and the upper boom 6 rotatably connected to the tip of the lower boom 5 are divided into two parts. Further, the upper boom 6 has an arm 7 rotatably connected in a vertical direction via a cylinder stay 8 at a tip thereof, and a bucket 9 for excavation as a front attachment is linked to a tip of the arm 7 by a link. They are connected via the mechanism 10. A rod 19 is fixed between the lower boom 5 and the cylinder stay 8. Then, between the upper swing body 2 and the lower boom 5,
Hydraulic cylinders 11, 12, 1 are respectively provided between the lower boom 5 and the upper boom 6, between the cylinder stay 8 and the arm 7, and between the arm 7 and the link mechanism 10.
3, 14 are attached, and the front working mechanism 3 is operated by driving these hydraulic cylinders. In particular,
With the expansion and contraction of the hydraulic cylinder 12 by the stay 19 described above, the upper boom 6 rotates in the left-right direction with respect to the lower boom 5, and the above-described work such as diving is performed.

FIG. 5 shows a known upper boom 6 which constitutes a part of the upper boom of the front work mechanism 3.
The upper boom 6 has a box shape with a hollow rectangular cross section formed by connecting four metal plates by welding means, and the rod 12a of the hydraulic cylinder 12 is connected to an appropriate position on the side surface thereof. A pair of brackets 15 and 16 are provided for this purpose.

[0005]

By the way, in the conventional upper boom 6, the pair of brackets 15 and 16 are formed as separate members, and both are fixed to the side surface of the upper boom 6 by welding. Not only is the work complicated and laborious for attaching the bracket, but also the welded portions thereof are weak in strength, and when the brackets 15 and 16 receive the thrust of the hydraulic cylinder 12, stress concentrates on the welded portion. It has a drawback that it is easily separated from the welded portion. Moreover, since the upper boom is generally hollow and weak in strength, it is desirable to take some reinforcement measures. For this reason, in the past, there is a partition wall for reinforcement provided inside, but since this partition wall is installed parallel to the axis of the upper boom, there is a reinforcement effect for the thrust of the cylinder, but a sufficient reinforcement effect for torsion. I couldn't say that.

The present invention has been made in view of the above points, and it is an object of the present invention to install a bracket for mounting a cylinder in the upper boom used for the front working mechanism of the construction machine as described above. In addition to simplifying, the installation strength and the strength of the boom as a whole against torsion and the like are increased.

[0007]

In order to achieve the above-mentioned object, the upper boom of the present invention is formed by a plurality of metal plates to have a hollow rectangular cross section, and a fluid pressure cylinder is connected to its side surface. In addition to having a pair of first and second brackets, a partition wall for reinforcement is provided inside,
A first bracket of the pair of brackets is integrally formed with a part of the metal plate by extending a part of the metal plate in a side surface direction of the upper boom, and the partition wall is provided in an installation area of the bracket. It is characterized in that it is provided in a direction orthogonal to the axis of the upper boom.

As described above, since the first bracket, which is one of the pair of brackets for mounting the cylinder, is formed integrally with the metal plate forming the upper boom, both of the two brackets are attached by welding. Compared with the above, not only the welding work is halved and the bracket can be installed easily and inexpensively, but also the stress concentration on the welded portion is improved and the installation strength is increased. Further, since the reinforcing partition wall is provided in the bracket installation area in a direction orthogonal to the axis of the upper boom, the strength of the entire upper boom against twisting or the like can be increased.

Here, it is desirable that the partition is installed between the cylinder mounting hole formed in the bracket and one end of the bracket. Further, the partition wall has three sides fixed to the inner surface of the upper boom, and the remaining one side is not fixed, and the non-fixed side is cut out in an arc shape. By notching the non-fixed side of the partition wall in an arc shape in this way, the partition wall can easily follow the deformation due to the twisting of the upper boom, so that the partition wall is reliably prevented from being peeled off or damaged due to the deformation of the upper boom. It

By the way, the first bracket is provided integrally with a metal plate which constitutes the upper boom, and its installation strength is enhanced, but the second bracket is fixed to another metal plate by welding. Therefore, in order to balance the strength of these two brackets, the welding line of the second bracket may be lengthened. For this reason, from the both ends of the first bracket, that is, the interval between both rising portions from the metal plate,
The length of the welded portion of the second bracket may be made longer.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, the upper boom incorporated in the front working mechanism of the hydraulic excavator shown in FIG. 4 is described, but the upper boom of the present invention is not limited to such hydraulic excavator.

The upper boom 20 shown in FIGS.
A main body 21 that is hollow and has a rectangular cross-sectional shape and has a so-called box shape, first and second connecting portions 22 and 23 formed at both ends of the main body 21, and one side surface of the main body 21. A pair of first and second opposing brackets 24, 25 for connecting the cylinders, and the main body 2
1 and a partition wall 26 for reinforcement provided inside. Therefore, the first connecting portion 22 is connected to the lower boom,
The second connecting portions 23 are connected to the cylinder stays via connecting pins, respectively.

The main body 21 includes four metal plates, that is, left and right side plates 28a and 28b and the side plates 28a and 28b.
A thicker upper plate 29 and a lower plate 30 are formed so as to have a vertically long rectangular cross section by being joined to each other by means such as welding, and the left and right side plates 28a and 28b are connected to the second connecting portion. By gradually narrowing toward the 23 side, the main body portion 21 has the largest cross-sectional area on the first connecting portion 22 side, and the cross-sectional area gradually decreases toward the second connecting 23 portion side. , Is formed in an elongated rectangular tube shape.

The first connecting portion 22 and the second connecting portion 23
For connecting the upper boom 20 to the lower boom 5 and the arm 7 as shown in FIG. 6, and connecting holes 22a, 23a in a direction intersecting the axis of the main body 21.
And the lower boom 5 and the arm 7 are pivotally supported by the lower boom 5 and the arm 7 by these connecting holes.

The pair of brackets 24 and 25 are used to rotatably connect the tips of the rods of the hydraulic cylinder. The brackets 24 and 25 are formed in an unequal-sided chevron shape with a rounded top. It has a pin insertion hole 32 near the top, and is located on the side surface of the main body portion 21 near the second connecting portion 23.
The rods are vertically arranged side by side with a space required for fitting the rod tips to each other. One of the first brackets 24 is a part of the lower plate 30 for the upper boom 20.
The second bracket 24 on the other side is formed separately from each metal plate by extending in the lateral direction of the side plate 28 of the main body 21.
It is fixed to a by welding. Moreover, these first
The second brackets 24 and 25 are arranged near the tip of the upper boom 20, that is, at a position close to the second connecting portion 23.

Thus, the first bracket 24 is attached to the lower plate 30.
By being integrally formed with the two brackets 24,
Compared to the case where both brackets are fixed by welding, not only the welding work is halved and the installation work of the brackets 24 and 25 becomes easier and cheaper than the conventional product in which both 25 are attached by welding. As a result, stress concentration on the welded portion is improved, and its installation strength is increased. Moreover, the position where the brackets 24 and 25 are provided is near the tip of the upper boom 20, and the main body portion 21 of the upper boom 20 is
Has a thin tip. Therefore, the bracket 24,
The position of 25 is the portion where the deformation is smallest when a large load acts on the upper boom 20. As a result, the load applied to the first bracket 24 is distributed to the lower plate 30 which is integral with the first bracket 24 and is reliably and efficiently supported by the lower plate 30. On the other hand, the thrust of the cylinder also acts on the other second bracket 25 fixed by welding. Therefore, if the strengths of both brackets 24 and 25 are not balanced, it is considered that a large stress acts on the welded portion of the second bracket 25. To avoid this situation,
As shown in FIG. 1, by making the welding length D2 of the second bracket 25 to the side plate 28a longer than the entire length of the first bracket 24, that is, the length D1 of the protrusion from the lower plate 30, The installation strength of the two brackets 25 may be increased.

The partition wall 26 mounted inside the main body portion 21 is a metal plate cut to fit the cross-sectional shape of the upper boom 20. It is fixed by welding in a direction orthogonal to the axis line of. That is, this partition wall 26
Is the right and left side edges 26a, 26b and the bottom edge 2 which form a straight line
6c and an upper side 26d that is cut in an arc shape that curves inward, and has an end 24 on the first connecting portion 22 side of the bracket 24.
Fixed by welding the three sides of the left and right side edges 26a and 26b and the lower edge 26c to the left and right side edges 28a and 28b and the lower edge 30 in the region L between the a and the center of the cylinder pin insertion hole 32. The upper side 26d cut out in an arc shape is not fixed.

By thus providing the reinforcing partition wall 26 in the installation region of the brackets 24, 25 in a direction orthogonal to the axis of the upper boom 20, the strength of the entire upper boom against twisting, bending, etc. is increased. You can
Moreover, the partition wall 26 is provided in the region L between the position corresponding to the pin insertion hole 32 in the bracket 24, 25 and the end portion of the bracket 24, 25. And the partition wall 2
By notching the upper side 26d of 6 in an arc shape with the upper side 26d being unfixed, the bending load is released by the notch when the partition wall 26 exerts a twisting force on the upper boom 20. That is, in the axial direction of the main body portion 21 of the upper boom 20, the strength of the mounting portion of the hydraulic cylinder on which the largest load acts is improved by the partition wall 26, and then the partition wall 26 is completely closed in the main body portion 21. The structure is not a rigid structure, but a partially open flexible structure. As a result, it becomes easier to follow the deformation in the twisting direction, so that the partition wall 26 is reliably prevented from being peeled off or damaged due to the deformation of the upper boom 20.

[0019]

As described above, the upper boom of the present invention is
Since one of the pair of brackets is integrally formed with the metal plate forming the upper boom, the welding work is halved compared to the conventional product in which the two brackets are attached by welding. Not only is the installation easier and cheaper, but the stress concentration on the weld is improved, the installation strength is increased, and the load applied to the first bracket by the thrust of the cylinder is distributed to the metal plate integrated with it. The metal plate is securely and efficiently supported, and the partition wall for reinforcement is provided in the bracket installation area in the direction orthogonal to the axis of the upper boom, thereby increasing the strength of the entire upper boom against twisting and the like. it can.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of an upper boom according to the present invention.

FIG. 2 is a bottom view of FIG.

3 is a cross-sectional view of FIG.

FIG. 4 is a side view of a hydraulic excavator that is an example of a construction machine.

FIG. 5 is a side view of a conventional upper boom.

[Explanation of symbols]

20 upper boom 24,25 bracket 24a end 26 partitions 26a, 26b side 26c lower side 26d Upper side 32 mounting holes

Claims (4)

[Claims] 1. A front working mechanism of a construction machine,
An upper boom connected between a lower boom extending from the machine body and an arm for mounting an attachment such as a bucket, which is formed by a plurality of metal plates into a hollow rectangular cross-sectional shape.
It has a pair of first and second brackets for connecting the hydraulic cylinders to the side surface, and has a partition wall for reinforcement inside, and the first bracket of the pair of brackets is a part of the metal plate. The partition wall is integrally formed with the metal plate by extending in the side direction of the upper boom, and the partition wall is provided in the installation area of the bracket in a direction orthogonal to the axis of the upper boom. Upper boom for construction machinery. 2. The construction machine upper according to claim 1, wherein the partition wall is installed at a position between a cylinder mounting hole formed in the bracket and one end of the bracket. boom. 3. The partition wall has three sides fixed to the inner surface of the boom, and the remaining one side is not fixed, and the non-fixed side is cut out in an arc shape. The upper boom for construction machinery according to Item 1 or 2. 4. The second bracket is fixed by welding means to another metal plate that is joined to a metal plate integrally formed with the first bracket, and the second bracket is connected to the metal plate at a connecting portion. The upper boom for a construction machine according to claim 1, wherein a length is larger than a space between the rising portions on both sides of the first bracket.