JPH0344832Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention provides a central boss portion of a work equipment support boom that is welded approximately at the center of the work equipment support boom to an opening in a side plate of the work equipment support boom and a connecting member passing through the openings to connect a luffing cylinder. Regarding the improvement of

[Conventional technology]

As shown in FIG. 5, the structure of the work equipment support boom 20 used for hydraulic excavators and other construction machinery includes an upper plate 23, a lower plate 24, and left and right side plates 22, 2.
2 and is formed into a box-shaped cross section. A cylindrical connecting member 28 is connected to the inner space of the boom 20 between openings 22a, 22a, which are transparently provided opposite to the left and right side plates 22, 22 at the center in the longitudinal direction of the work equipment support boom 20 in the extending direction. It is arranged so as to pass through the section horizontally. The central boss portion that connects one end of the undulating cylinder has a configuration in which a connecting base 25b and an undulating cylinder connecting portion 25a that protrudes in a cylindrical shape are connected to the connecting base 25b. That is, the connecting base 25b has an inner flange 26 that protrudes inward so as to be substantially flush with the end of the connecting member 25 in a direction opposite to the protruding direction of the central boss portion 25.
and an outer flange 27 that extends in the circumferential direction and has an L-shaped cross section and is perpendicular to the projecting direction. The inner flange 26 has an inner end connected to the connecting member 2.
The outer flange 27 is welded to the edge of the opening 22a of the side plate 22. Here, the connecting base portion 25b of the central boss portion 25 is
In order to moderate the flow of stress to each of the welded parts, the shape is gently tapered toward the welded parts, but the overall shape is highly rigid. Therefore, when a bending load is applied to the box-shaped cross-sectional beam of the work equipment support boom 20 that is curved due to the operation of the work equipment, the cross-sectional shape tends to be significantly deformed. The side plates 2 are connected horizontally via the central boss portion 25.
2 is restrained, and restraint (bending) stress is concentrated on the welded portion between the central boss portion 25 and the side plates 22. If this concentration of restraint (bending) stress poses a problem in terms of strength, conventional measures have been taken such as increasing the thickness of the side plate 22 or using tabling, but this has been done in terms of cost and performance. It will be disadvantageous on

[Problem that the invention attempts to solve]

In view of the above circumstances, the inventor of the present invention conducted intensive research and found that the central boss section is intended for load transmission, and therefore, contrary to the conventional wisdom that a shape that increases rigidity is effective in terms of strength, the present inventor found that In order to alleviate the restraint (bending) stress caused by the deformation of the cross section, it was found that it is more advantageous to make the central boss part have a flexible structure, and this led to the completion of the present invention. That is, the problem of the present invention is to prevent the connection between the connecting member that passes through the box-shaped cross section of the work equipment support boom and the central boss part, and the connection between the side plate of the work equipment support boom and the central boss part from being integral. The purpose of this is to disperse the restraining stress by flexing without transmitting the load when the load is applied separately.

[Means to solve the problem]

In order to solve the above-mentioned problems, this invention is designed to provide a work equipment support boom that is arranged approximately at the center of the work equipment support boom with a box-shaped cross section, between the openings that are transparently provided opposite to the left and right side plates of the work equipment support boom. and is welded to the end of the connecting member that penetrates the inner space of the work equipment support boom substantially horizontally and to the edge of the opening of the both side plates, and protrudes outward to connect one end of the undulation cylinder. In the central boss part of the work equipment support boom, the central boss part (a) is provided with a branch part in the middle of the luffing cylinder connection part that protrudes outward from the surface formed by the side plate of the work equipment support boom; (b) an outer flange that extends circumferentially from the branch part and gradually inclines inward, and is welded to the periphery of the opening of the work equipment support boom; (c) from the branch part to the outer flange through a gap; A technical measure is taken in which an inner flange is provided that extends inward and is welded to the end edge of the connecting member.

[Effect]

The inner flange and the outer flange are separated by a gap at a branch part that is formed at a position that protrudes outward from the surface formed by the side plate of the work equipment support boom, so the outer flange is not elastically deformed. When a load is applied to the work equipment support boom, the load applied to the side plate is not concentrated locally but is dispersed. In other words, when a load is applied, stress is applied in the direction that the side plate deforms, and this stress is received at the welded part between the side plate and the outer flange, but the outer flange is connected to the inner flange in the direction in which the side plate extends Since the gap is provided, the outer flange can be elastically bent so as to be able to recover from the load from the side plate. As a result, the outer flange welded to the side plate does not collide with the inner flange welded to the connecting member and do not become integral, so the connecting member does not restrain the side plate and suppresses the generation of restraint (bending) stress. can.

【Example】

Hereinafter, a preferred embodiment in which the central boss portion of the working machine support boom of this invention is used in a boom of a hydraulic excavator will be described with reference to the drawings. A work equipment support boom (hereinafter referred to as "boom") 10 shown in FIG. 1 is formed into a box-shaped cross section by an upper plate 3, a lower plate 4, and left and right side plates 2, 2. As shown in FIGS. 3 and 4, the boom 10 has a shape that extends in the front-rear direction and has a curved central portion in the longitudinal direction. Approximately at the center of the boom 10, left and right side plates 2, 2
A cylindrical connecting member 5 is horizontally disposed so as to pass through the inner space of the boom 10 between openings 2a, 2a which are transparently provided opposite to each other. As is clear from FIG. 1, the opening 2a
A central boss portion 1, which is welded to the inner end side of the connecting member 5 and the connecting member 5, projects outward. The central boss portion 1 has an undulating cylinder connecting portion 11 on the distal end side, and an outer flange 14 and an inner flange 13 are provided on the inner end side via a branch portion 12. That is, in the case of this embodiment, the undulating cylinder connecting portion 1
1 has a cylindrical shape, and the extendable end of the undulating cylinder 30 is pivotally connected to it by a pin (not shown), but the shape of the undulating cylinder connecting portion 11 is not limited to the above embodiment, The shape may be such that the extendable ends are held from both sides. Further, a branching part 12 is formed in the middle of the protruding direction of the undulating cylinder connecting part 11, and an outer flange 14 extends from the branching part 12 while tilting inward in the circumferential direction of the undulating cylinder connecting part 11. , an inner flange 13 is provided which extends inward in the axial direction of the undulating cylinder connecting portion 11 with a gap 15 interposed between the outer flange 14 and the outer flange 14 . The outer flange 14 has a horizontally bent C-shaped cross section and is elastic, and as shown in FIG. They collide and are welded in series. Further, in the case of this embodiment, the inner flange 13 extends parallel to the axial direction from the branch portion 12 and then expands through the stepped portion so as to be concentric with the annular end edge of the connecting member 5. A series of annular ends are formed, and as shown in FIG. 2, a step 13a is formed on the annular end, and the end edges of the connecting member 5 are abutted and welded on the outside in the circumferential direction. . The shape of the inner flange 13 is not particularly limited as long as its inner end substantially coincides with the edge of the connecting member 13, and the rest of the shape can provide a gap between it and the outer flange. Not done. Furthermore, the gap 15 between the inner flange 13 and the outer flange 14 is an annular groove that is opened toward the inner end from the branch portion 12 in the middle that protrudes outward from the surface formed by the side plate 2 of the boom 10. It is made up of As a result, when a load is applied to the boom 10 during work, etc., the main part of the stress applied to the side plate 2 is received by the elastic outer flange 14, causing it to bend so that it can return to its original state. As a result, most of the stress that tends to deform the box-shaped cross section of the boom can be absorbed by the elastic deformation of the outer flange. Therefore, a large load is not directly applied to the connecting member serving as the beam having the box-shaped cross section, and accordingly, the restraint (bending) stress between the side plate and the outer flange can be significantly alleviated. In this invention, the boom is not limited to construction machinery, but includes booms that can be used for other heavy machinery as long as they are used to support working equipment.

[Effect of the idea]

In response to the load on the work equipment supporting boom that occurs during work, the restraint bending stress that is generated by deforming and restraining the side plate of the boom can be alleviated by using the flexible structure of the central boss part. , it is possible to improve the reliability of the work equipment support boom. In addition, a flexible structure can be achieved simply by providing an inner flange and an outer flange at the central boss with a gap between them, so measures such as thickening the side plates of the work equipment support boom and tab rings can be used. This is extremely beneficial as it allows weight reduction and cost reduction without the need for additional measures.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a preferred embodiment of the central boss portion of the work equipment support boom of the present invention, Fig. 2 is an enlarged sectional view showing the welded part of Fig. 1, and Fig. 3 is a perspective view of the boom. FIG. 4 is a partial perspective view showing the center portion of the boom, and FIG. 5 is a sectional view showing the conventional center boss portion. DESCRIPTION OF SYMBOLS 1... Central boss part, 2... Side plate, 2a... Opening, 5... Connecting member, 10... Boom, 11...
Lifting cylinder connection part, 12... Branch part, 13...
Inner flange, 14... Outer flange, 15...
Gap, 30... undulation cylinder.

Claims (1)

[Scope of Claim for Utility Model Registration] The work equipment supporting boom is disposed approximately at the center of the work equipment support boom having a box-shaped cross section, between openings provided through the work equipment support boom so as to face the left and right side plates of the work equipment support boom. The working equipment supporting boom is welded to the end of the connecting member that penetrates the inner space of the boom substantially horizontally and to the edge of the opening of the both side plates, and protrudes outward to connect one end of the luffing cylinder. In the central boss part, the central boss part has a branch part in the middle of the undulating cylinder connecting part that protrudes outward from the surface formed by the side plate of the work equipment support boom, and extends from the branch part in the circumferential direction and gradually moves inward. an outer flange that extends inward from the branch portion through a gap with the outer flange and is welded to the edge of the connecting member; A central boss portion of a work equipment support boom, comprising an inner flange.