JP2013238077A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of an upper frame capable of securing the strength thereof while suppressing increase of weight.SOLUTION: In a rear end portion of an upper frame 4 constituting a super structure 3, a counter weight 10 is fixed. The upper frame 4 comprises a bottom plate 11, and a longitudinal plate 12 which is erected on the bottom plate 11 and extends in a longitudinal direction of the bottom plate 11. A front part 14 of the longitudinal plate 12 is formed in a mountain shape having an apex 14a to which a proximal end portion of a work attachment 9 is mounted. In the longitudinal plate 12, a second mountain-shaped part 15 is formed in a middle portion tilting obliquely downward from the apex 14a to a rear part of the longitudinal plate 12.

Description

  The present invention relates to a structure of an upper frame constituting an upper swing body of a construction machine such as a hydraulic excavator.

  The background art will be described taking the hydraulic excavator described in Patent Document 1 as an example. As shown in FIG. 5 of Patent Document 1, various facilities including a cabin 4 are mounted on the upper frame 3 constituting the upper swing body 2 of the excavator. A work attachment 8 including a boom 5, an arm 6, and a bucket 7 is attached to the front portion of the upper frame 3, and a counterweight 9 is attached to the rear end portion of the upper frame 3.

  As shown in FIG. 6 of Patent Document 1, the upper frame 3 is provided with a bottom plate 10 over a wide range, and a pair of left and right vertical parts extending substantially in the front-rear direction at an intermediate portion in the vehicle width (left-right) direction. Plates (sometimes referred to as vertical ribs) 11 and 12 are attached to the bottom plate 10 by welding. The main frame of the upper frame 3 is configured by the bottom plate 10 and the vertical plates 11 and 12.

  Further, for example, the base end portion of the work attachment 8 shown in FIG. 5 of Patent Document 1 is formed on the top of each front portion (mountain shape portion) of each of the vertical plates 11 and 12 shown in FIG. It is attached.

JP 2009-55795 A

  Here, when the load acting from the work attachment 8 side and the load acting from the counterweight 9 side are simultaneously applied to the vertical plate 11 (12) constituting the upper frame 3, the longitudinal direction intermediate of the vertical plate 11 (12) The conventional vertical plate 11 (12) has a structural strength problem that stress is concentrated on the portion. The strength of the vertical plate 11 (12) can be increased by increasing the thickness of the vertical plate 11 (12). However, in this method, the thickness of the vertical plate 11 (12) must be very large, The weight increase is tremendous.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an upper frame structure that can ensure strength while suppressing an increase in weight.

  The present invention is a construction machine in which an upper swing body is mounted on a lower traveling body. A counterweight is fixed to the rear end of the upper frame constituting the upper swing body. The upper frame includes a bottom plate and a vertical plate standing on the bottom plate and extending in the front-rear direction of the bottom plate. The front portion of the vertical plate has a mountain shape having a top portion to which a base end portion of a work attachment is attached. The vertical plate is inclined obliquely downward from the top portion toward the rear portion of the vertical plate. A second mountain-shaped portion is formed in the portion.

  According to the present invention, when the load acting from the work attachment side and the load acting from the counterweight side are simultaneously applied to the vertical plate, the load propagation can be dispersed by the second mountain-shaped portion formed on the vertical plate. This makes it possible to ensure the strength of the vertical plate. And since the method of simply increasing the thickness of a vertical board is not taken, the weight increase of a vertical board (upper frame) can also be suppressed.

It is a side view of a hydraulic excavator which is an example to which the present invention is applied. It is a perspective view of a part of an upper frame according to an embodiment of the present invention. FIG. 3 is a plan view of FIG. 2. FIG. 3 is a perspective view showing a state in which a hydraulic oil tank is attached to the upper frame shown in FIG. 2. FIG. 5 is a plan view of FIG. 4.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is applied to, for example, a hydraulic excavator among various construction machines.

  As shown in FIG. 1, a hydraulic excavator 1 is a construction machine in which an upper turning body 3 is mounted on a crawler type lower traveling body 2 so as to be turnable around a vertical axis (turning center) O. Various facilities including a cabin 5 are mounted on the upper frame 4 which is a structure of the upper swing body 3 of the excavator 1. A work attachment 9 including a boom 6, an arm 7, and a bucket 8 is attached to the front portion of the upper frame 4, and a counterweight 10 is attached to the rear end portion of the upper frame 4.

  The structure of the upper frame 4 of the present embodiment will be described with reference to FIGS. In the following description, the side on which the work attachment 9 is mounted is referred to as the front direction, and the “front and rear” and “left and right” directions are referred to based on this side.

  The upper frame 4 constituting the upper swing body 3 includes a bottom plate 11 serving as a base and a vertical plate 12 erected on the bottom plate 11 by welding. A counterweight 10 is fixed to the rear end portion of the bottom plate 11. In addition, although the vertical board erected on the bottom plate 11 is usually a pair of left and right identically shaped plates arranged at predetermined intervals in the left-right direction of the bottom plate 11, in FIGS. The other vertical plate is not shown. The counterweight may be fixed to the rear end portion of the vertical plate instead of the rear end portion of the bottom plate.

(Vertical board)
The vertical plate 12 is erected on the bottom plate 11 in a direction extending in the front-rear direction of the bottom plate 11. The front portion 14 of the vertical plate 12 has a mountain shape having a top portion 14a to which the base end portion of the work attachment 9 is attached.

  A second mountain-shaped portion 15 is formed on the vertical plate 12 at a midway portion inclined obliquely downward from the top portion 14 a toward the rear portion of the vertical plate 12. The 2nd mountain shaped part 15 has the horizontal part 15a and the inclination part 15b. The top portion 14a side is a horizontal portion 15a.

  The vertical plate 12 is a plate formed by cutting a single steel plate, for example. That is, the second mountain-shaped portion 15 of the present embodiment is not retrofitted to the vertical plate by welding or the like.

  In the present embodiment, rib plates 20 and 21 are provided below the second mountain-shaped portion 15 formed on the vertical plate 12 with a predetermined interval. The lower surfaces of the rib plates 20 and 21 are fixed to the bottom plate 11 by welding, and the side surfaces of the rib plates 20 and 21 are fixed to the vertical plate 12 by welding. The rib plates 20 and 21 are arranged in a direction orthogonal to the vertical plate 12 and the bottom plate 11. A rib plate 20 is provided vertically below one end of the horizontal portion 15a, and another rib plate 21 is provided vertically below the other end of the horizontal portion 15a. That is, in the present embodiment, the length of the horizontal portion 15a and the interval between the rib plates 20 and 21 are substantially equal.

(Function and effect)
Here, a load acting from the work attachment 9 side and a load acting from the counterweight 10 side may be simultaneously applied to the vertical plate 12. For example, when traveling on rough ground with unevenness, the excavator 1 swings up and down. At this time, the load acting from the work attachment 9 side and the load acting from the counterweight 10 side are simultaneously applied to the vertical plate 12.

  In the present embodiment, the second mountain-shaped portion 15 having a predetermined height is provided at a midway portion inclined obliquely downward from the top portion 14a of the front portion 14 of the vertical plate 12 toward the rear portion of the vertical plate 12, so that the work attachment is provided. Even if the load acting from the 9 side and the load acting from the counterweight 10 side are applied to the vertical plate 12 at the same time, the load propagation is dispersed in the second mountain-shaped portion 15. Thereby, damage to the vertical plate 12 can be prevented (strength of the vertical plate 12 can be ensured).

  The main large load among the loads acting on the vertical plate 12 from the work attachment 8 is a bending load in the vertical direction A shown in FIG. Further, the main large load among the loads acting on the vertical plate 12 from the counter weight 9 through the bottom plate 11 is a bending load in the vertical direction B shown in FIG. Thus, both the load acting from the work attachment 9 side and the load acting from the counterweight 10 side are mainly bending loads in the vertical direction.

  Here, the strength of the vertical plate 12 can be secured by increasing the thickness of the vertical plate 12. However, since the thickness direction of the vertical plate 12 is not the vertical direction in which the bending load acts, even if the plate thickness of the vertical plate 12 is increased, the vertical section modulus in which the bending load acts does not increase so much. That is, in the method of increasing the plate thickness of the vertical plate 12, the plate thickness must be made very large.

  On the other hand, according to the method of providing the second mountain-shaped portion 15 on the vertical plate 12 as in the present embodiment, the vertical section modulus on which the bending load acts is greater than the method of increasing the plate thickness of the vertical plate 12. Can be dramatically increased. In other words, an increase in the weight of the vertical plate 12 can be suppressed as compared with a method of increasing the thickness of the vertical plate 12.

  In the present embodiment, the rib plates 20 and 21 are provided below the second mountain-shaped portion 15 formed on the vertical plate 12. Since the side surfaces and the lower surface of the rib plates 20 and 21 are fixed to the vertical plate 12 and the bottom plate 11, respectively, the load propagation can be further dispersed by the rib plates 20 and 21.

(Tank support by vertical plate)
A tank support member 16 is attached to the second mountain-shaped portion 15 formed on the vertical plate 12. A tank support member 18 is also attached to the upper surface of the bottom plate 11. As shown in FIG. 4, in this embodiment, the hydraulic oil tank 17 is mounted on the bottom plate 11 via these tank support members 16 and 18. The hydraulic oil tank 17 is a tank for storing hydraulic oil for moving the work attachment 9, the lower traveling body 2, and the like.

  In the present embodiment, the tank support member 16 is attached to the upper portion of the side surface opposite to the side on which the hydraulic oil tank 17 is mounted in the second mountain-shaped portion 15. A mounting bracket 19 is provided near the center of the side surface of the hydraulic oil tank 17 in the vertical direction (see FIG. 5). The hydraulic oil tank 17 and the tank support member 16 are bolted through the mounting bracket 19.

(Function and effect)
In this way, by using the second mountain-shaped portion 15 formed on the vertical plate 12 as the tank support portion, the tank can be fixed at a position close to the center of gravity of the tank (a position where the tank is high). Thereby, it is possible to prevent high stress from being generated in the tank support members 16 and 18 under severe vibration conditions such as when the hydraulic excavator 1 travels on rough and uneven ground. As a result, damage to the hydraulic oil tank 17 and the tank support members 16 and 18 can be prevented. In other words, since high stress can be prevented from being generated in the tank support members 16 and 18, the strength of the tank support members 16 and 18 can be reduced as compared with the conventional case, and as a result, the hydraulic excavator 1 is reduced in weight. be able to.

  Furthermore, in this embodiment, the upper part of the side surface opposite to the side on which the hydraulic oil tank 17 is mounted in the second mountain-shaped portion 15 is used as the tank support portion. Thereby, the distance between the hydraulic oil tank 17 and the vertical board 12 can be made small, and the layout of the apparatus and piping mounted on the bottom board 11 becomes easy to do by that much. This contributes to downsizing of the excavator 1.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

1: Hydraulic excavator 2: Lower traveling body 3: Upper swing body 4: Upper frame 9: Work attachment 10: Counter weight 11: Bottom plate 12: Vertical plate 14: Front portion 14a of vertical plate: Top portion 15: Second mountain-shaped portion 16, 18: Tank support member 17: Hydraulic oil tank 20, 21: Rib plate

Claims (4)

In a construction machine in which an upper turning body is mounted on a lower traveling body,
A counterweight is fixed to the rear end of the upper frame constituting the upper swing body,
The upper frame is
The bottom plate,
A vertical plate standing on the bottom plate and extending in the front-rear direction of the bottom plate;
With
The front portion of the vertical plate has a mountain shape having a top portion to which a base end portion of a work attachment is attached,
The construction machine according to claim 1, wherein a second mountain-shaped portion is formed on the vertical plate at a midway portion inclined obliquely downward from the top portion toward the rear portion of the vertical plate. The construction machine according to claim 1,
A construction machine, wherein a rib plate having a lower surface fixed to the bottom plate and a side surface fixed to the vertical plate is provided below the second mountain-shaped portion. The construction machine according to claim 1 or 2,
The construction machine characterized in that the second mountain-shaped part is used as a tank support part. The construction machine according to claim 3,
A construction machine, wherein an upper portion of a side surface of the second mountain-shaped portion opposite to the side on which the tank is mounted is used as a tank support portion.

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