JPS5853345Y2 - Structure of boom of hydraulic excavator, etc. - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a boom for a hydraulic excavator or the like.

In general, work attachments for construction machinery are required to have the strength to withstand the work load, and are also designed to be lightweight in order to improve work performance.

The present invention is intended to provide a new boom structure that can maintain sufficient strength, improve quality, and improve welding workability in booms for hydraulic excavators and the like.

An embodiment will be described below with reference to the accompanying drawings.

1 is a boom of a hydraulic excavator, 2 is an arm, and 3 is a packet, which are rotatably connected by connecting pins 4, 5, and 6, respectively.

7 is a cylinder that supports the boom 1, and 8 is a cylinder that supports the arm 2.

Reference numeral 9 denotes a cylinder for supporting the packet, which is supported as a whole by the revolving body.

The boom 1 has a box-like structure composed of an upper flange 10, a lower flange 11, and left and right webs 12 (third
(Fig.), thereby creating a structure that can withstand the bending load and torsional load necessary to support the arm 2.

Reference numeral 13 denotes a partition wall provided within the boom 1, which provides sufficient strength and rigidity to prevent cross-sectional deformation due to torsional loads.

The bulkhead 13 has upper and lower flanges 10.1 whose entire circumference constitutes a box.
1 and the left and right flanges, but since the box is sealed, one of the four sides of the bulkhead cannot be welded from the inside.

Assuming that the lower flange 11 is to be assembled last, both the left and right sides b (Fig. 3) of the partition wall 13 will be welded to the web 12, but the lower side a cannot be welded to the lower flange 11 from the inside, so it will not be possible to weld it as it is during work. Due to the shearing force generated in the lower flange 11 when subjected to a torsional load, stress tends to concentrate at the corners of the sides a and b, and there is a possibility that the nearby web 12 etc. will be easily damaged.

Therefore, it is necessary to weld the lower side a. (Conventionally, as shown in FIG. 3, a hole was made in the lower flange 11 and a plug weld 14 was performed.

Alternatively, as shown in FIG. 4, the partition wall 13'' whose lower part is bent is similarly plug-welded 14' through a hole made in the lower flange 11, or a welding hole is made in the web 12 and the lower side a is inserted through the hole. The method used was to weld the plate so as to close the hole in the web 12 after welding.

As mentioned above, according to the conventional method, due to holes for welding the flanges and webs, stress concentration on the flanges and webs,
The section where the partition wall is located becomes weak due to sudden changes in the section modulus.

For this reason, manufacturing costs have been forced to increase due to thicker flanges and webs or special welding.

Furthermore, the increased weight of the boom made the machine less stable, leading to a problem of poor excavation performance.

The present invention was devised to solve the problem of slanting, and will be explained with reference to FIGS. 5 to 8.

According to the present invention, one end of the bulkhead 13' is provided with a bulkhead flange 1 whose width increases from the center toward the width of the boom.
5 are welded at right angles (Figure 7).

Further, a backing metal 16 is welded to one inner end of the left and right webs 12' so as to project outward from the one end, and the tip edge of this backing metal 16 and the end surface of the bulkhead flange 15 are flush with each other. It has become.

Note that the backing metal 16 is welded to the inner lower ends of the left and right webs 12', but is not present inside the partition flange 15.

Now, in order to assemble the boom, the upper flange 10' and the left and right webs 12' are welded together in a U-shaped cross-section. are welded to the inner surfaces of the upper flange 10' and the left and right webs 12', respectively.

Then, the lower flange 11' is applied from below to the backing metal of the bulkhead flange 10' and the left and right webs 12', and the left and right webs 12' and the lower flange 11' are connected continuously from the outside of the backing metal and the bulkhead flange. Weld it into a box shape.

In this case, the portion where the left and right webs 12' and the lower flange 11' are to be welded is formed on the outside of the portion where the side edges of the bulkhead flange 15 and the backing metal 16 protrude and abut on the lower flange 11'. Welded into the recess.

With the above configuration, the partition wall 13' is connected to the upper flange 10'.
, the left and right webs 12' and the lower flange 11' are all continuously welded to form a box-shaped cross section.

In addition, in the above embodiment, the lower flange 11' is finally welded to form a box shape, but the same effect can be obtained even if the upper flange 10' or the left and right webs 12' are welded last. Needless to say.

According to the above configuration, the lower flange 11' is connected to the left and right webs 1.
2' and the backing metal 16, and the partition walls connected by continuous welding d and connected to the upper flange 10' and the left and right webs 12' are also connected to the side edges of the partition flange 15. Welded by continuous welding.

In this way, unlike the lower flange 11' of the boom, which is welded at discontinuous points in plug welding as shown in Figure 4, the lower flange 11' of the boom is welded at the side edge of the bulkhead flange, which also serves to prevent weld metal from flowing inside. Since the parts are continuously welded, there is no stress concentration and a boom with excellent strength can be obtained.

In addition, since no bulkhead welding has been performed on the upper and lower flanges or the left and right webs, there is no sudden change or decrease in the section modulus, and
This greatly contributes to reducing the weight and cost of the boom by shortening welding time.

The above was explained as the structure of the boom of a hydraulic excavator, etc.
The present invention can be applied to all box-shaped steel structures.

[Brief explanation of the drawing]

Figure 1 is a side view of the hydraulic excavator, Figure 2 is a side view of the boom, Figure 3 is a sectional view taken along line III--III in Figure 2, and Figure 4 is a side view of the hydraulic excavator.
The figure is a sectional view showing another welded structure of the bulkhead, FIG. 5 is a sectional view showing the boom structure according to the present invention, FIG. 6 is a sectional view of the boom without the bulkhead flange, and FIG. Vll of
-vtt sectional view, and FIG. 8 is a right side view of FIG. 7. In the figure; 10, 10'...upper flange,
11.11'...Lower flange, 12...
・Left/right web, 13.13', 13"...Bulkhead, 14.14'...Plug welding, 15...
・Flange for bulkhead, 16...Backing metal, a...
...Bottom side of partition wall, b...Left and right sides of partition wall, C...
...Top side of bulkhead, d...Butt weld.

Claims (1)

[Scope of utility model registration request] In the boom 1, which has a box-shaped cross section with an upper flange 10', left and right webs 12' that are substantially parallel to each other, and a lower flange 11' that is substantially parallel to the upper flange, and is reinforced with a partition wall 13' that is separated from the upper flange 10', , three sides of the upper and lower flanges 10', 11' and the left and right webs 12', 12' are welded together to form a U-shaped cross section with an opening on one side, and a partition wall 13 is provided at intervals on the inner surface thereof. At the same time, a bulkhead flange 15 whose width increases from the center in the width direction of the boom 1 is fixed to the remaining unwelded side of the bulkhead 13', and the flange or web on the opening side is welded. A backing metal 16 is welded to the inner end so as to project outward, and one of the upper and lower flanges or the web, which is the remaining side, is welded to the outside of this backing metal 16 and the bulkhead flange 15. A structure of a boom for a hydraulic excavator, etc., characterized in that the boom is continuously welded in the longitudinal direction of the boom in contact with each other.