JP7272028B2 - boom structure - Google Patents

Description

The present invention relates to boom construction.

Telescopic booms used in cranes and aerial work platforms are desired to be longer in the extended state. can be longer. However, increasing the number of booms increases the weight of the telescopic boom as a whole, degrading the load lifting performance.

Therefore, it is necessary to reduce the weight of the telescopic boom, and the plate thickness of each stage of the boom should be reduced. However, if the plate thickness of each boom is simply reduced, the rigidity of the boom is lowered, and there is a possibility that the required specifications cannot be satisfied.

As a structure for increasing the rigidity of the boom, a structure in which a bent portion is formed on the side surface of the boom or the like has been proposed (see, for example, Patent Documents 1 and 2).

JP-A-2000-16763 Register No. 2575542

Both of the technologies disclosed in Patent Documents 1 and 2 described above have a welded portion connecting the boom in the circumferential direction on the side surface of the boom, and a bent portion above the welded portion. is formed.

The present invention has been made in view of the above circumstances, and has a structure of a boom that can reduce the load applied to the welded portion when the welded portion connecting the boom in the circumferential direction is formed on the side surface of the boom. intended to provide

According to the present invention, at least a part of a plurality of booms constituting a telescopic boom includes an upper member, which corresponds to a portion above the axis of the boom, and has a plurality of bent portions formed thereon, and A lower member, which corresponds to the lower part, and which has more bent portions than the upper member, is welded by butting the ends of the respective cross sections in the circumferential direction, so that the cross section is a polygonal cylinder The boom has a welded portion in which the upper member and the lower member are butt-welded on a flat portion of the side surface of the polygonal tube, and is orthogonal to the longitudinal direction of the boom. Among the plurality of bent portions of the upper member in the cross section, the bent portion that is closest to the welded portion, and the bent portion that is closest to the welded portion among the plurality of bent portions of the lower member, The two bent portions formed in the vertically symmetrical portions of the plurality of booms are formed in vertically symmetrical portions with the weld portion interposed therebetween, and the two bent portions formed in the vertically symmetrical portions have substantially an internal angle that is a bending angle. A construction of a boom in which the interior angles of all the folds formed in the lower member of the proximal boom are identical and identical.

According to the boom structure according to the present invention, when the welded portion connecting the boom in the circumferential direction is formed on the side surface of the boom, the load applied to the welded portion can be reduced.

1 is a schematic diagram showing an aerial work vehicle 1 having a telescopic boom according to the present invention; FIG. FIG. 2 is a perspective view showing a main part of the telescopic boom of FIG. 1; FIG. 3 is a cross-sectional view showing a cross section along a plane perpendicular to the axis C of the telescopic boom shown in FIG. 2 (a plane along line AA); Figure 4 is a cross-sectional view similar to Figure 3 showing the proximal boom shown in Figure 3; Figure 4 is a cross-sectional view similar to Figure 3 showing the first intermediate boom shown in Figure 3; Figure 4 is a cross-sectional view similar to Figure 3 showing the second intermediate boom shown in Figure 3; FIG. 4 is a cross-sectional view corresponding to FIG. 3 showing Modification 1 of the embodiment; FIG. 4 is a cross-sectional view corresponding to FIG. 3 showing Modification 2 of the embodiment;

Hereinafter, specific embodiments of the positioning structure for the slide member according to the present invention will be described with reference to the drawings.

<Embodiment>
(Configuration of aerial work platform)
FIG. 1 is a schematic diagram showing an aerial work vehicle 1 having a telescopic boom 10 according to the present invention, FIG. 2 is a perspective view showing a main part of the telescopic boom 10 of FIG. 1, and FIG. 3 is the telescopic boom shown in FIG. 4 is a cross-sectional view showing a cross-section taken along a plane perpendicular to axis C (a plane along line AA); FIG.

The aerial work vehicle 1 shown in FIG. is provided with a bucket 8 on which a worker is placed.

The telescopic boom 10 is provided on a swivel base 4 that can swivel with respect to the loading platform 2 with respect to the loading platform surface. A base bracket 5 is installed on the swivel base 4, and the base end of the telescopic boom 10 (the end in the direction of the axis C of the telescopic boom 10 toward the base bracket 5 (base end direction B) in FIG. 2) is , is supported by the base bracket 5 so as to be capable of swinging in a vertical plane.

Similarly, one end is held by the base bracket 5, and the other end is located forward of the base end of the telescopic boom 10 (in the direction toward the tip in the direction of the axis C (longitudinal direction) of the telescopic boom 10 (front end direction F)). As the held hoisting cylinder 6 expands and contracts, the telescopic boom 10 rotates about the base end as the center of rotation, thereby hoisting and lowering with respect to the loading platform 2 .

As shown in FIGS. 2 and 3, the telescopic boom 10 has, for example, five booms 11, 12, 13, 14, and 15 telescopically accommodated, and each of the booms 12 to 15 extends forward in the tip direction F in the direction of the axis C. It is configured to extend by protruding to. The five booms 11 to 15 constituting the telescopic boom 10 are the outermost base end boom 11 directly supported by the base bracket 5 and the first intermediate boom housed inside the proximal end boom 11. 12, a second intermediate boom 13 housed immediately inside the first intermediate boom 12, a third intermediate boom 14 housed immediately inside the second intermediate boom 13, and the inside of the third intermediate boom 14. It is composed of a top boom 15 housed in.

The telescopic boom 10 has a base end boom 11, a first intermediate boom 12, a second intermediate boom 13, a third intermediate boom 14, and a top boom 15 arranged in order from the outside to the inside.

The telescopic boom 10 has the shortest length (completely retracted) with each of the booms 12 to 15 housed in the relatively outer boom (outer boom) the longest. From this fully retracted state, the booms 12 to 15 other than the base end boom 11 extend in the direction of the axis C by projecting in the distal direction F with respect to the respective outer booms.

Inside the telescopic boom 10, a telescopic cylinder 50 is provided whose one end is fixed to the base end side portion of the base end boom 11, and the booms 12 to 15 are simultaneously projected by the extension and contraction of the telescopic cylinder 50. or accommodated at the same time, and the telescopic boom 10 as a whole expands and contracts.

As shown in FIG. 1, the bucket 8 is positioned above and in front of the cabin 3 of the vehicle at a reference position in which the telescopic boom 10 is retracted (the minimum hoisting angle, the telescopic length is fully retracted, and the turning direction is slightly forward and to the right). The aerial work vehicle 1 has a mechanism for maintaining the bucket 8 horizontally regardless of the hoisting angle of the telescopic boom 10, the telescopic state of the telescopic boom 10, and the turning angle of the telescopic boom 10. (not shown).

The aerial work platform 1 also includes outriggers 7, 7 that project in the width direction of the vehicle and are installed on the road surface, respectively, at the front and rear parts of the loading platform. Each of the front and rear outriggers 7 is extended to an appropriate length according to the undulating state, the telescopic state and the turning state of the telescopic boom 10, and rises and leaves the road surface when the vehicle is running.

(Boom structure)
4 is a sectional view similar to FIG. 3 showing the base end boom 11 shown in FIG. 3, FIG. 5 is a sectional view similar to FIG. 3 showing the first intermediate boom 12 shown in FIG. 3, and FIG. 4 is a cross-sectional view similar to FIG. 3 showing the second intermediate boom 13 shown in FIG.

As shown in FIGS. 3 and 4, the base end boom 11 is formed in a polygonal tubular shape in a cross section perpendicular to the axis C direction. As shown in FIG. 4, the base end boom 11 includes an upper member 11B corresponding to a portion substantially above the axis C and a lower member 11A corresponding to a portion substantially below the axis C. It is formed by butting and welding the ends of the cross section in the circumferential direction.

That is, the upper member 11B has an upside-down angular U-shaped cross section (hereinafter referred to as an angular U-shape), while the lower member 11A has a substantially U-shaped cross section. . As will be described in detail later, the lower member 11A has a larger number of bent portions 11d and the like than the upper member 11B, and the distance between the bent portions is shorter.

The upper member 11B has an upside-down angular U-shaped end in cross section and the lower member 11A has a substantially U-shaped end in cross section which are butted against each other, and the butted portions are joined by welding to form a circumferential shape. It forms a closed polygonal cylindrical cross-section connected in direction.

Two welded portions 11C joining the upper member 11B and the lower member 11A (there are two welded portions in the cross-sectional view of FIG. 4, but each welded portion 11C is formed extending in the direction of the axis C). , which are two welded portions 11C for the base end boom 11 ) are formed on both side surfaces of the base end boom 11 .

Each welded portion 11C is formed on a flat portion of the side surface of the base end boom 11 because the end portion of the upper member 11B and the end portion of the lower member 11A are butted and joined in a state of being arranged on the same plane. It is supposed to be

The base end boom 11 has a polygonal tubular shape as described above, but the upper surface is formed in a horizontal plane, and the range from the upper surface to one side surface, the lower surface, the other side surface, and the upper surface is 21 pieces. Bending portions 11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h, 11i, 11j. 11k, 11m, 11n, 11o, 11p, 11q, 11r, 11s, 11t, 11u, and 11v are formed. All the bent portions 11a to 11v are bent in mountain folds. In other words, the internal angle of each bent portion 11a to 11v is less than 180[°].

Here, the bent portion 11a and the bent portion 11v are formed at symmetrical portions with respect to a vertical plane passing through the axis C in the state shown in FIG. Similarly, the bent portion 11b and the bent portion 11u, the bent portion 11c and the bent portion 11t, the bent portion 11d and the bent portion 11s, the bent portion 11e and the bent portion 11r, and the bent portion 11f and the bent portion The portion 11q, the bent portion 11g and the bent portion 11p, the bent portion 11h and the bent portion 11o, the bent portion 11i and the bent portion 11n, and the bent portion 11j and the bent portion 11m also pass through the axis C. They are formed at symmetrical positions with respect to the vertical plane.

The two corresponding bent portions 11a, 11v, etc. formed in the above-described symmetrical portions have the same interior angle. The bent portion 11k is formed at the lowest portion of the base end boom 11 on the vertical plane passing through the axis C. As shown in FIG.

Further, the two bent portions 11c and 11d, which are the closest to one of the welded portions 11C, are formed vertically symmetrically with the welded portion 11C interposed therebetween. That is, the distance of the bent portion 11c from the welded portion 11C and the distance of the bent portion 11d from the welded portion 11C are equal. Specifically, for example, the bent portion 11c is formed at a position 58 [mm] above the welded portion 11C, and the bent portion 11d is formed at a position 58 [mm] below the welded portion 11C.

The two bent portions 11t and 11s, which are the closest to the other welded portion 11C, are similarly formed in vertically symmetrical portions with the welded portion 11C interposed therebetween. Specifically, for example, the bent portion 11t is formed at a position 58 [mm] above the welded portion 11C, and the bent portion 11s is formed at a position 58 [mm] below the welded portion 11C.

The two bent portions 11c and 11d, which are arranged vertically symmetrically, are also set to have the same internal angle (for example, an angle of 168 [°]). On the other hand, the two vertically symmetrical bent portions 11t and 11s are similarly set to have the same internal angle (for example, an angle of 168 [°]). there is

In addition, the length along the circumferential direction between two adjacent bent portions below the welded portion 11C is approximately the same length as the distance between the welded portion 11C and the nearest bent portion 11d ( The difference between the welded portion 11C and the nearest bent portion 11d is set to a length equal to or less than approximately 20[%]), which is a relatively short length.

For example, the length between the bent portions 11d and 11e is 69 [mm], the length between the bent portions 11e and 11f is 60 [mm], the length between the bent portions 11f and 11g is 60 [mm], The length between the bent portions 11g and 11h is 60 [mm], the length between the bent portions 11h and 11i is 36 [mm], the length between the bent portions 11i and 11j is 36 [mm]. The length between the portions 11j and 11k is set to 36 [mm].

The length between the bent portions 11s and 11r is 69 [mm], the length between the bent portions 11r and 11q is 60 [mm], and the length between the bent portions 11q and 11p is 60 [mm]. The length between the portions 11p and 11o is 60 [mm], the length between the bent portions 11o and 11n is 36 [mm], the length between the bent portions 11n and 11m is 36 [mm], and the bent portion 11m , 11k is set to 36 [mm].

The interior angles of the bent portions 11d, 11e, . . . , 11s are set to the same angle of 168 [°].

On the other hand, the length between the bent portions 11c and 11b above the welded portion 11C is 140 [mm], the length between the bent portions 11b and 11a is 60 [mm], and the length between the bent portions 11a and 11v is 140 [mm]. The length is 304 [mm], and the length between the bent portions 11t and 11u is 140 [mm]. It is set longer than the others.

According to the base end boom 11 of this embodiment configured as described above, the number of bent portions 11a and the like is 21, which is extremely large compared to the conventional art, so that the rigidity of the base end boom 11 can be increased. . Therefore, even if the plate thickness of the base end boom 11 is made thinner than before, it is possible to prevent or suppress the strength of the base end boom 11 from being lowered.

Further, according to the base end boom 11 of the present embodiment, the number of bent portions 11d, etc. below the welded portion 11C is set to be greater than the number of bent portions 11c, etc. above the welded portion 11C. Therefore, the buckling strength of the lower side where the load is relatively large can be enhanced intensively.

In addition, according to the base end boom 11 of the present embodiment, since the welded portions 11C, 11C are provided in the flat portion of the side surface (particularly, near the center portion in the vertical direction (near the vertical axis C)), Welding distortion that occurs during welding can be reduced.

Further, according to the base end boom 11 of the present embodiment, in the cross section perpendicular to the axis C, the bent portions 11c and 11d and the bent portions 11c and 11d are provided at substantially symmetrical upper and lower portions sandwiching the welded portions 11C and 11C. Since 11t and 11s are formed, the load applied to the welded portion 11C can be evenly dispersed vertically.

Moreover, the base end boom 11 of the present embodiment has bending angles (that is, internal angles (bend angle=180−internal angle)), the load applied to the welded portion 11C can be evenly distributed vertically.

In addition, the base end boom 11 of the present embodiment includes a bent portion 11a formed between the horizontal upper surface and the side surface of the base end boom 11, and a bent portion formed in the upper portion across the welded portion 11C. Since another bent portion 11b is formed between the bent portion 11c and the bent portion 11c, it is possible to prevent a long flat surface between the bent portion 11a and the bent portion 11c.

The flat portion with a long distance has lower rigidity than the flat portion with a short distance, but the bent portion 11b is formed on the flat portion with a long distance, and the flat portion with a long distance is combined with two flat portions with a short distance. By doing so, it is possible to improve the rigidity.

Further, the bent portions 11a and 11v of the base end boom 11 receive a reaction force from the first intermediate boom 12 arranged inside the base end boom 11 via a slide member or the like. If a flat portion with low rigidity and a long distance is formed on the upper side of the welded portion 11C, the fluctuation of the reaction force causes the long flat portion to alternately change into a concave shape and a convex shape. , abnormal noise is generated during the change. Furthermore, this long flat portion can become a starting point of shear deformation when a large reaction force acts.

However, since the base end boom 11 of the present embodiment avoids forming a flat portion with a long distance by the bent portion 11b, it is possible to prevent or suppress the occurrence of abnormal noise and shear deformation.

In the telescopic boom 10 of the present embodiment, the first intermediate boom 12 shown in FIG. formed on the flat part of the Also, the number of bent portions 12c to 12r formed below the welded portion 12C is greater than the number of bent portions 12b, 12a, 12t, and 12s formed above. Further, the bent portions 12b, 12c and the bent portions 12s, 12r are formed in vertically symmetrical portions with respect to the welded portion 12C.

Therefore, the first intermediate boom 12 in the telescopic boom 10 of this embodiment also exhibits the same effects as the base end boom 11 .

Furthermore, in the telescopic boom 10 of the present embodiment, the second intermediate boom 13 shown in FIG. , is formed on the flat part of the side. Also, the number of bent portions 13c to 13r formed below the welded portion 13C is greater than the number of bent portions 13b, 13a, 13t, and 13s formed above. Further, the bent portions 13b, 13c and the bent portions 13s, 13r are formed in vertically symmetrical portions with respect to the welded portion 13C.

Therefore, the second intermediate boom 13 in the telescopic boom 10 of this embodiment also exhibits the same effect as the base end boom 11 does.

In the telescopic boom 10 of the present embodiment, as shown in FIG. 3, the third intermediate boom 14 and the top boom 15 are not a structure in which two members, ie, an upper member and a lower member are joined together, but a single member. is bent into an annular shape, and the ends are connected to each other at a flat portion on the upper surface (in FIG. 3, the welded portion is a black portion), so the present invention is not applied, but the second The present invention may also be applied to the intermediate boom 14 and the top boom 15.

Further, the telescopic boom 10 of the present embodiment is obtained by applying the present invention to the base end boom 11, the first intermediate boom 12 and the second intermediate boom 13, but the plurality of booms 11 constituting the telescopic boom 10 15 may be applied to at least one boom, and is not limited to three booms 11, 12, and 13 as in the present embodiment.

<Modification 1>
FIG. 7 is a sectional view corresponding to FIG. 3, showing Modification 1 of the above-described embodiment.

In the embodiment described above, the base end boom 11 is configured such that the internal angle of all the bent portions is set to be less than 180[°], and all the bent portions are mountain folds. The shape is not limited, and, for example, as shown in FIG. 7, a part of the bent portion may be a valley-folded portion with an internal angle exceeding 180[°].

Here, the telescopic boom 110 of Modified Example 1 shown in FIG. 7 has a proximal end boom 111 (a welded portion 111C is formed by butting and welding the ends of an upper member 111B and a lower member 111A). The first intermediate boom 12 is accommodated inside the first intermediate boom 12, the second intermediate boom 13 is accommodated inside the second intermediate boom 13, the third intermediate boom 14 is accommodated inside the third intermediate boom A top boom 15 is housed inside 14 .

The first intermediate boom 112 of Modification 1 is the same as the first intermediate boom 12 of the embodiment, and the other booms 13, 14, 15 of Modification 1 are also the same as the booms 13, 14, 15 of the embodiment. is.

The proximal boom 111 of Modification 1 is located between the bent portion 111a corresponding to the bent portion 11a and the bent portion 111b corresponding to the bent portion 11b of the proximal boom 11 in Embodiment 1, and Between the portion 111b and the folded portion 111c corresponding to the folded portion 11c, valley-folded portions 111w and 111x with an internal angle exceeding 180[°] are formed, and similarly corresponding to the folded portion 11v. The internal angle between the bent portion 111v and the bent portion 111u corresponding to the bent portion 11u and between the bent portion 111u and the bent portion 111t corresponding to the bent portion 11t exceeds 180[°]. Valley folds 111z and 111y are formed.

The base end boom 111 of Modification 1 has bent portions 111c, 111d and bent portions 111t, 111s formed vertically symmetrically with respect to the welded portion 111C. exerts its effect on

Further, in the base end boom 111 of Modification 1, in addition to the mountain-folded bent portions 111a to 111v, two bent portions 111w and 111x sandwiching one mountain-folded bent portion 111b are formed in valley folds. , two bent portions 111z and 111y sandwiching one mountain-folded bent portion 111u are formed as valley-folded.

As a result, the rigidity of the portion including the two valley folds 111w and 111x and the portion including the two valley folds 111z and 111y can be increased compared to the proximal boom 11 of the embodiment. can.

In addition, by forming the bent portions 111w and 111x and the bent portions 111z and 111y of the valley folds on the flat portions above the welded portion 11C and having a longer distance than the lower portion, the The base end boom 111 can more effectively prevent or suppress the occurrence of noise and shear deformation compared to the base end boom 11 of the embodiment.

<Modification 2>
FIG. 8 is a sectional view corresponding to FIG. 3, showing Modification 2 of the above-described embodiment.

In the above-described embodiment and Modification 1, the lowermost portions of the proximal booms 11 and 111 are the bent portions 11k and 111k. However, the present invention is not limited to this embodiment. , the lowermost portion may be a flat surface instead of a bent portion.

Here, the telescopic boom 210 of Modified Example 2 shown in FIG. 8 has a proximal end boom 211 (a welded portion 211C is formed by butting and welding the ends of an upper member 211B and a lower member 211A). The first intermediate boom 212 is accommodated inside the first intermediate boom 212, the second intermediate boom 213 is accommodated inside the second intermediate boom 213, the third intermediate boom 214 is accommodated inside the third intermediate boom A top boom 215 is accommodated inside 214 .

The booms 211 to 215 constituting the telescopic boom 210 of the modified example 2 differ in the number of bent portions from the booms 11 to 15 of the embodiment and the booms 111, 12 to 15 of the modified example 1. For example, the base end boom 211 , 18 bent portions 211a to 211s are formed.

The bent portions 211b and 211c are vertically symmetrical with the welded portion 211C interposed therebetween, and the bent portions 211r and 211q are vertically symmetrical with the welded portion 211C interposed therebetween.

As described above, the proximal boom 211 of Modification 2 has an even number of bent portions 211a to 211s, and the 18 bent portions 211a to 211s are formed symmetrically. A horizontal flat portion between 211i and the bent portion 211j is the lowest portion of the base end boom 211 in cross section.

Since the base end boom 211 of Modification Example 2 has bent portions 211b, 211c and bent portions 211r, 211q formed in vertically symmetrical portions with respect to the welded portion 111C, the base end boom 11 of the embodiment has a modified shape. It exhibits the same effects as the base end boom 111 of Example 1.

Furthermore, in the base end boom 211 of the modified example 2, since the lowest part of the base end boom 211 is a horizontal flat surface, when the base end boom 211 is placed on a horizontal surface for manufacturing, or when the base end boom 211 is When removing the 211 from the aerial work vehicle 1 and placing it on a horizontal surface, etc., by grounding the horizontal flat surface of the lowest part, the lowest part is less likely to fall compared to the bent part, and the stationary state is stable. and can be maintained.

The above-described embodiment and modified examples 1 and 2 are the boom structure of the telescopic boom 10 used in the aerial work vehicle, but the boom structure according to the present invention is limited to the telescopic boom of the aerial work vehicle. Instead, it can be applied to a telescopic boom of a crane.

In the above-described embodiment and modified examples 1 and 2, the bent portion formed on the upper side and the bent portion formed on the lower side with the welded portion sandwiched are at exactly the same position from the welded portion. In the structure of the boom according to the invention, the upper bent portion and the lower bent portion may not be formed in strictly symmetrical portions with the weld portion interposed therebetween.

Specifically, if the difference between the distance from the welded part to the upper bent part and the distance from the welded part to the lower bent part is within 20 [%], it is included in the range of approximately symmetry. be The range of approximately symmetry is preferably within 10[%].

1 Aerial work vehicle 10 Telescopic boom 11 Base end boom 11C Welded part 11a-11k Bent part 11m-11v Bent part C Axis

Claims (5)

At least some of the booms constituting the telescopic boom include an upper member having a plurality of bent portions corresponding to a portion above the axis of the boom, and a portion below the axis. The lower member corresponding to the upper member, which has more bent portions than the upper member, is butted against and welded at the ends of the respective cross sections in the circumferential direction, so that the cross section is formed in a polygonal cylindrical shape. ,
The boom has a welded portion in which the upper member and the lower member are butted and welded to a flat portion of the side surface of the polygonal tube,
In a cross section orthogonal to the longitudinal direction of the boom, a bent portion of the plurality of bent portions of the upper member that is closest to the welded portion, and the welded portion of the plurality of bent portions of the lower member. The nearest bent portion of is formed in a vertically symmetrical portion across the welded portion,
In the base end boom among the plurality of booms, the two bent portions formed in the vertically symmetrical portion have substantially the same internal angle, which is a bending angle,
A construction of a boom in which the interior angles of all the folds formed in the lower member of the proximal boom are the same. The lower member of the proximal boom includes a flat portion between a lowermost bent portion of the plurality of bent portions and an upper bent portion adjacent to the lower bent portion; The length of at least two or more adjacent flat portions including the flat portion between one bent portion and the next upper bent portion adjacent to the upper bent portion has the same length. Boom construction as described. 3. The method according to claim 2, wherein at least two or more planar portions adjacent to two or more of the planar portions having the same length in the proximal boom are the same with a length longer than the same length. boom structure. 4. Any one of claims 1 to 3, wherein another fold is formed between the fold of the upper member and a corner formed at the edge of the flat top surface of the boom. Boom construction as described in paragraph 1. 5. The boom structure according to any one of claims 1 to 4, wherein the lowermost part of said cross section is formed horizontally.

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