JP2003328383A - Boom for drilling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid excessive stress concentration on a joint portion between the lower wall end of a boom and a pivotally supporting end member. <P>SOLUTION: A boom body 40 is formed in a cylindrical shape with a side-to- side wall 43 and upper and lower walls 44, 45. It is fixed to the pivotally supporting end member 41 inserted into the end of the boom body 40 in such a manner that an end 45a of at least the lower wall 45 of the upper and lower walls 44, 45 is shifted from to the end of the side-to-side wall 43 in the longitudinal direction of the boom body 40. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boom of an excavator mounted on a swing working machine such as a backhoe.

[0002]

2. Description of the Related Art Generally, a backhoe is provided with a revolving machine body on a traveling device so as to freely rotate around a vertical axis, and an excavator is mounted on the revolving machine body so that the excavator can swing left and right. The pivot support end member is formed by inserting and fixing the pivot support end member into the end portion of the boom main body, which is formed in a substantially U-shaped cross section in a side wall and upper and lower walls and is substantially V-shaped in side view. Is pivotally supported on the swing body via the horizontal axis, and an arm having a bucket is pivotally supported on the tip end side pivotal end member via the horizontal axis.

In the boom, the boom main body is formed of an iron plate or the like, and the pivot end member is formed by casting or forging. After inserting the end portion of the pivot end member into the end portion of the boom main body, It is fixed by welding around the edges. At the end of the boom body, the left and right side walls and the upper and lower walls are located at substantially the same position in the boom body longitudinal direction.

[0004]

Generally, when excavation work is performed, high stress is concentrated on the joint between the end of the boom body and the pivot end member that receives the excavation reaction force, and the boom is exposed to the stress. Constructed with sufficient strength. However, as in the prior art, while the left and right side walls of the boom main body and the ends of the upper and lower walls are substantially at the same position in the longitudinal direction of the boom main body, for example, the revolving machine body is swung 30 degrees to the left and back, and It was found that excessive stress concentration occurs on the upper and lower parts of the end of the boom body, especially on the lower wall connecting part of the pivot end member when the work is hit against the wall (sideways work).

In order to counter this excessive concentrated stress,
Although it is possible to change the structure of the pivot end member, the manufacturing cost of the pivot end member increases and the weight also increases. It is an object of the present invention to provide a boom for an excavator that can solve the problems of the conventional art. According to the present invention, by displacing at least the end of the lower wall of the upper and lower walls of the boom main body with respect to the ends of the left and right side walls in the longitudinal direction of the boom main body, an excessive stress is applied to the lower wall connecting portion of the pivot end member. An object of the present invention is to provide a boom of an excavator that can avoid concentration.

[0006]

The present invention takes the following specific means to solve the problems. First, the boom main body 40 formed into a tubular shape by the left and right side walls 43 and the upper and lower walls 44, 45 is different from the upper and lower walls 44, 44 with respect to the pivot end member 41 inserted into the end of the boom main body 40. That is, at least the end portion 45a of the lower wall 45 among the 45 is shifted and fixed in the longitudinal direction of the boom body 40. As a result, the stress applied between the pivotal end member 41 and the end of the boom body 40 is dispersed, and excessive stress concentration is avoided.

Second, the left and right side walls 43 and the upper and lower walls 44, 45
The boom main body 40 formed into a tubular shape by means of the pivot support end member 41 inserted into the end portion of the boom main body 40 has a stress concentration position between the lower wall 45 and the pivot support end member 41. It is fixed in a state in which the boom main body 40 is displaced in the longitudinal direction from the stress concentration position between the left and right side walls 43 and the pivot end member 41. Thereby, the stress applied between the pivot end member 41 and the end of the boom body 40 is
The stress concentration positions of the lower wall 45 and the lower wall 45 are different from each other, and local excessive stress concentration is avoided.

Thirdly, the end portion 45a of the lower wall 45 projects from the end portions of the left and right side walls 43 toward the pivot end member 41 side or is located closer to the center of the boom body 40 than the end portions of the left and right side wall 43. It is that you are. As a result, the end portion 45a of the lower wall 45, which is a stress concentration position with respect to the pivot end member 41, is displaced away from the stress concentration position of the left and right sidewalls 43 with respect to the pivot end member 41, and stress is reduced. Boom body 40
Dispersion in the longitudinal direction avoids local excessive stress concentration.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In FIG. 4, a turning work machine 1 exemplified as a rear small turning type backhoe is a running device 3 having a pair of left and right crawler running parts 2, and this running device 3
It is mainly configured to have a turning machine body 4 provided on the upper side so as to be freely rotatable, and an excavation device 5 mounted on the turning machine body 4. The crawler traveling unit 2 of the traveling device 3 supports driving wheels, driven wheels, and rolling wheels on both left and right sides of the track frame 7, and crawlers formed of elastic material such as rubber or metal are wound around these to drive the driving wheels. Is driven by a hydraulic motor 8 to circulate and circulate the crawler.

At the center of the upper surface of the track frame 7, the turning machine body 4 is mounted via a turning bearing 9. The swivel body 4 can be swung about a swivel axis 6, which is the vertical axis, by a swivel motor disposed inside. A swivel joint is arranged between the turning machine body 4 and the traveling device 3 on the turning axis 6. A dozer device 10 which is moved up and down by a hydraulic cylinder is pivotally mounted on the front portion of the track frame 7.
The turning machine body 4 has the excavator 5 mounted on the front end of the machine body frame 12 and the weight 13 for balancing the weight of the excavator machine 5 on the rear end of the machine body frame 12. An engine, a radiator, a hydraulic pump, and the like are arranged in the rear part.

On the right side of the body frame 12 to the right of the turning axis 6, at least one vehicle device such as a battery and a valve is mounted in addition to tanks such as a fuel tank and a hydraulic oil tank. The driver's seat 1 is located on the left side of the tanks and on the upper front side of the engine at a position overlapping the turning axis 6.
4 is arranged, and a substantially rear half of the driver's seat 14 overlaps with the engine in the front-rear direction. The center of the driver's seat 14 is offset to the left of the turning axis 6. The main cover 1 is located above and in front of the engine room where the engine and the like are arranged.
5, the rear of the engine room is covered with a bonnet cover 16, and the tank room on the right side where the fuel tank, the hydraulic oil tank, the battery, etc. are arranged is surrounded by the side cover 17 and the side cover. The upper opening of 17 is closed by a side upper cover 18. The interior of the engine room at the rear part and the tank room at the right part are connected to each other, and are substantially L-shaped in a plan view.

An operating device 20 is provided on the left and right sides of the driver's seat 14, and a steering lever 22 is provided above a floor 21 in front of the driver.
A driver's seat having pedals and the like is provided, and the driver's seat 14
Is covered by the shade device 23. Excavator 5
Is supported by a support bracket 26 protruding forward from the front surface of the swivel body 4, and a swing bracket mounted to the support bracket 26 so as to be swingable about a vertical axis (swing about a vertical axis). 27, a boom 28 pivotally connected to the swing bracket 27 so as to be swingable about the left and right axis, an arm 29 pivotally connected to the boom 28 so as to be swingable about the left and right axis, and this arm 29, and a bucket 30 pivotally supported so as to be swingable about the left and right axis.

The support bracket 26 is connected to the front ends of a pair of left and right vertical ribs 34 of the machine body frame 12, and a pair of upper and lower bearing portions is provided with a swing bracket 27 via a vertical axis 35.
Is swingably supported from side to side. Swing bracket 2
The swing cylinder 7 is swing-driven by a swing cylinder provided in the turning machine body 4. The boom 28 is vertically rocked by a boom cylinder 31 arranged along the lower front side of the boom 28, and the arm 29 is rocked back and forth by an arm cylinder 32 arranged along the upper upper side of the boom 28. Driven, the bucket 30 is scooped and dumped by a bucket cylinder 33 arranged along the front side (upper side) of the arm 29.

1 to 4, the boom 28 includes a boom body 40 having a substantially doglegged shape in a side view, a pivot end member 41A inserted and fixed to the base end side, and a pivot support inserted and fixed to the tip end side. And an end member 41B. The boom main body 40 has a rectangular tubular shape having a substantially rectangular cross section with the left and right side walls 43 and the upper and lower walls 44, 45. It is formed by cutting or the like, and becomes thinner from the center side in the longitudinal direction toward both ends.

The pivot end member 41 is formed by casting or forging, and the base end pivot end member 41A has a bearing portion 41a pivotally connected to the swing bracket 27 via the horizontal shaft 46, and the tip end side thereof. The pivot end member 41B has a bearing 41a pivotally connected to the arm 29 via the horizontal shaft 47, and each pivot end member 41A, 41B has an end opposite to the bearing 41a at the boom body 40. The boom body 40 is fixed in place by being welded into the inside thereof and by welding the entire circumference of the end edge of the boom body 40. Next, the connecting structure of the base end side pivotal end member 41A and the boom body 40 will be described. Although the structure of the tip-side pivotally supporting end member 41B is slightly different from that of the base-end-side pivotally supporting end member 41A, the coupling structure with the boom body 40 is substantially the same.

The pivot end member 41A has a bifurcated bearing portion 41a formed from a midway portion 41b of the internal cavity toward one end thereof.
The opposite end portion is the insertion end portion 41c, and the intermediate portion 4
A bulging portion 41d that protrudes toward the bearing portion 41a is formed in 1b, and a partition wall 41e is formed in the insertion end portion 41c. The pivotal support end member 41A is inserted into the end of the boom body 40 up to the root of the insertion end 41c, and is fixed to each other by fillet welding or the like so that the bead is inserted near the midway portion 41b.

At the end of the boom main body 40, the end edges of the left and right side walls 43 and the upper wall 44 are located at substantially the same position, but the end edge of the lower wall 45 is more bearing than the end of the left and right side walls 43. Part 41
It projects to the a side (the pivot end member 41 side), and the left and right side walls 4
It is located in the longitudinal direction of the boom body 40 with respect to the end portion of No. 3. That is, the distance L1 from the center of the horizontal axis 46 to the edge of the lower wall 45 is set shorter than the distance L2 from the center of the horizontal axis 46 to the left and right side walls 43. On the contrary, the edge of the lower wall 45 is located at the position indicated by the line P in FIG. 1 (the position closer to the center of the boom body 40 than the ends of the left and right side walls 43),
That is, even if the end portions of the left and right side walls 43 are formed to be shorter than the end portions of the left and right side walls 43, the end portions of the left and right side walls 43 can be displaced in the longitudinal direction of the boom body 40. That is, the distance L3 from the center of the horizontal axis 46 to the edge of the lower wall 45 indicated by the line P is 4
It may be set longer than the distance L2 from the center of 6 to the left and right side walls 43.

To shift the end edge of the lower wall 45 in the longitudinal direction of the boom main body 40 with respect to the end portions of the left and right side walls 43, the lower end of the pivot support end member 41 inserted into the end portion of the boom main body 40 is lowered. The stress concentration position between the wall 45 and the pivot end member 41 is shifted in the longitudinal direction of the boom body 40 from the stress concentration position between the left and right side walls 43 and the pivot end member 41. Displace the end position of the lower wall 45,
It is possible to avoid local concentration of stress during lateral application work. The shift amounts W1 and W2 of the edges of the lower wall 45 with respect to the ends of the left and right side walls 43 are such that the edges of the lower wall 45 are the left and right side walls 43.
Since the stress concentration is maximized when it substantially coincides with the ends of (W1, W2 = 0), the edge of the lower wall 45 can be moved from the ends of the left and right side walls 43 to a position where welding is not hindered. It is preferable to keep them away, but even if the shift amounts W1 and W2 are around 5 mm,
It has the necessary and sufficient effect to avoid stress concentration.

The present invention is not limited to the above embodiment, but can be variously modified. For example,
Although the boom 28 is exemplified by a backhoe, it may be one having an excavator such as a front loader, a tractor loader backhoe (TLB), or the like. The cross-sectional shape of the boom 28 may be circular, elliptical, or the like, instead of being quadrangular. Furthermore, the edge of the upper wall 44 may be displaced from the end of the left and right side walls 43 in the same direction as the lower wall 45, in the opposite direction, or by the same amount or a different amount.

[0020]

According to the present invention described in detail above, the stress applied between the pivotal end member 41 and the end of the boom body 40 can be dispersed to avoid excessive stress concentration.

[Brief description of drawings]

FIG. 1 is a side view of essential parts showing an embodiment of the present invention.

FIG. 2 is a plan view of the main part.

FIG. 3 is a perspective view of the main part from below.

FIG. 4 is an overall side view of a backhoe.

[Explanation of symbols]

1 swivel work machine 5 excavation equipment 28 boom 40 Boom body 41 Pivot end member 41a bearing part 41b Midway part 41c insertion part 41d bulge 41e partition wall 43 Side wall 44 Upper wall 45 Lower wall 45a end 46 Horizontal axis L distance W shift amount

Claims (3)

[Claims] 1. An end portion of a boom main body formed in a tubular shape with left and right side walls and an upper and lower wall is at least lower than the pivot end member inserted into the end portion of the boom main body. A boom for an excavator, wherein the end of the wall is fixed to the ends of the left and right side walls by shifting in the longitudinal direction of the boom body. 2. The end portion of the boom main body formed in a tubular shape by the left and right side walls and the upper and lower walls has the lower wall and the pivot support end member with respect to the pivot support end member inserted in the end portion of the boom main body. The boom of the excavator is characterized in that the stress concentration positions between and are shifted in the longitudinal direction of the boom body from the stress concentration positions between the left and right side walls and the pivot end member. 3. The end of the lower wall projects toward the pivot end member side from the ends of the left and right side walls, or is located closer to the center of the boom body than the ends of the left and right side walls. The boom of the excavator according to 1 or 2.