JPH0967080A - Overhead crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb kinetic energy generated by vertical vibration of the earthquake, and to restrain deflection of a crane girder, by fixing damping members formed of a mateiral having the yield stress lower than a mateiral for constituting the crane girder onto the upper surface and the lower surface of the crane girder of an overhead crane. SOLUTION: An overhead crane is provided with a crane girder 2 to be horizontally moved along a pair of right and left girder rails 1, 1 and having a box structure, and a trolley 3 to be loaded on the crane girder 2 and to be horizontally moved along the girder 2, and a hook block 4 capable of being freely raised and lowered is supported to the trolley 3. In this case, upper and lower damping members 8, 9 formed into plate shapes are fixed on both upper and lower surfaces of the crane girder 2. The damping members 8, 9 formed of a steel mateiral having the low yield stress of SS35 and the high Young's modulus or an extra mild steel. Therefore, kinetic energy of the crane girder 2, to be generated by vertical vibration of the earthquake is absorbed, and the deflection can be restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead crane having a seismic resistance function.

[0002]

2. Description of the Related Art FIGS. 7 to 9 show an example of a conventional overhead crane, which comprises a box-structured crane girder 2 which horizontally moves along a pair of left and right girder rails 1, 1. A trolley 3 which is mounted on the crane girder 2 and horizontally moves in a direction orthogonal to the girder rails 1 and 1, and a hook block which is located below the crane girder 2 and moves up and down with respect to the trolley 3. 4 and.

The girder rails 1 and 1 are laid horizontally so as to be parallel to each other on the upper surfaces of the beams 5 and 5 that are installed to face each other inside the building or the like.

The crane girder 2 has four web plates 2a extending in parallel to each other from above one girder rail 1 to above the other girder rail 1 and an upper edge portion of each web plate 2a. Has an upper face plate 2b welded and fixed horizontally, and a lower face plate 2c welded and fixed to the respective lower edge portions of the respective web plates 2a. The web plate 2a and the upper face plate The lower face plate 2b and the lower face plate 2c are both made of a steel material having a high yield stress such as SS50.

Openings 2 d, 2 penetrating the face plates 2 b, 2 c vertically and extending from the vicinity of one girder rail 1 to the vicinity of the other girder rail 1.
e is provided so as to be located between the second one and the third one of the four web plates 2a.

On the upper surface of the upper face plate 2b, a pair of trolley rails 6 and 6 extending in a direction orthogonal to the girder rails 1 and 1 are laid across the opening 2d.

At both ends of the crane girder 2, traveling wheels 2 rolling on the upper surfaces of the girder rails 1 and 1 are provided.
A traveling frame 2g having f is attached, and when a traveling drive device (not shown) including a motor and a gear reduction device equipped in the traveling frame 2g is operated, the traveling frame 2g is moved along the girder rails 1 and 1. The crane girder 2 moves horizontally.

The trolley 3 is composed of the trolley rails 6 and 6 described above.
Traversing frame 3 having traversing wheels 3a rolling on the upper surface of the vehicle
b, and a pair of brackets 3c, 3
c, and a drum 3d pivotally supported through the traverse drive device (not shown) including a motor and a gear reduction device mounted on the traverse frame 3b. The trolley 3 moves horizontally along the rails 6,6.

The hook block 4 includes a shell 4b for pivotally supporting the sheave 4a, and a hook 4c mounted on the shell 4b.
And

A base end of the sheave 4a is locked to the drum 3d of the trolley 3 and a front end of the sheave 4a is locked to the traverse frame 3b, and an intermediate portion of the sheave 4a has openings 2d of the face plates 2b and 2c. The wire rope 7 inserted through 2e is wound around from below, and when an elevating drive device (not shown) including a motor and a gear reduction device provided in the traverse frame 3b is actuated, The wire rope 7 is wound around the drum 3d or unwound from the drum 3d, whereby the hook block 4
Is designed to move up and down.

When the overhead crane shown in FIGS. 7 to 9 is affected by the vertical vibration of an earthquake, the crane girder 2 which is a beam supported at both ends has an acceleration of 1 G acting on the crane girder 2.
When it is less than the above, the intermediate portion bends upwardly and convexly with respect to both end portions, and the intermediate portion bends downward and convexly bends with respect to both end portions. .

Further, when the acceleration acting on the crane girder 2 exceeds 1 G, the left and right traveling wheels 2f, 2f rise from the upper surfaces of the girder rails 1, 1 and then fall on the upper surfaces of the girder rails 1, 1. It is repeated.

As described above, when the traveling wheels 2f are repeatedly lifted from the girder rail 1 and then dropped onto the girder rail 1, the crane girder 2, the trolley 3 mounted on the crane girder 2, and the girder girder are mounted. An impact force may act on the beam 5 or the like supporting the rail 1.

[0014]

As a means for preventing the crane girder 2 from being lifted up due to the bending caused by the vertical vibration of an earthquake, it is conceivable to apply a dynamic vibration absorber to an overhead crane.

However, when the dynamic vibration reducer is mounted on the crane girder 2, the bending of the crane girder 2 cannot be effectively damped unless the position of the trolley 3 with respect to the crane girder 2 is appropriate.

Further, when the trolley 3 is equipped with a dynamic vibration absorber, when the traverse wheel 3a of the trolley 3 is lifted from the trolley rail 6 when the acceleration due to an earthquake exceeds 1 G, the bending of the crane girder 2 is attenuated. Can't do it.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to effectively dampen the bending of a crane girder due to an earthquake in an overhead crane.

[0018]

In order to achieve the above object, in an overhead crane according to claim 1 of the present invention, a crane girder horizontally moving along a girder rail, and a crane girder mounted on the crane girder and In an overhead crane having a trolley that horizontally moves in a direction orthogonal to the girder rail of the above, at least one of the crane girder upper surface and the crane girder lower surface is made of a material having a yield stress lower than that of the material forming the crane girder. The member is fixed.

Further, in the overhead crane according to claim 2 of the present invention, in the overhead crane according to claim 1, the damping member is provided on at least one of the upper surface of the crane girder and the lower surface of the crane girder by fillet welding and plug welding. It is stuck.

In the overhead crane according to the first and second aspects of the present invention, the damping member absorbs the kinetic energy due to the vertical vibration of the earthquake and suppresses the bending of the crane girder.

In the overhead crane according to the second aspect of the present invention, the fillet welding and the plug welding effectively transfer the kinetic energy of the crane girder to the damping member.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an example of an embodiment of an overhead crane according to the present invention, in which FIG. 7 to FIG.
The parts denoted by the same reference numerals as those in FIG.

In the overhead crane shown in FIGS. 1 to 5, plate-shaped upper damping members 8 and lower damping members 9 are fixed to the crane girder 2.

The upper damping member 8 and the lower damping member 9
Has low yield stress like SS35 (15
kgf / mm ² ) Steel material with high Young's modulus or J
It is made of ultra-soft steel that does not meet the IS standard.

The upper damping member 8 is arranged along the trolley rail 6 from one end to the other end of the upper face plate 2b constituting the crane girder 2, and fillet welded. It is fixed to the upper face plate 2b by means of 10 and plug welding 11 (see FIG. 5).

The lower damping member 9 is welded and fixed to the lower surface of the lower face plate 2c constituting the crane girder 2 from the vicinity of one end of the lower face plate 2c to the vicinity of the other end.

The welding structure of the lower damping member 9 to the lower face plate 2c is similar to the welding structure of the upper damping member 8 to the upper face plate 2b described above.

The operation of the overhead crane shown in FIGS. 1 to 5 will be described below.

When the overhead crane is affected by the vertical vibration of the earthquake, the crane girder 2 which is a support beam for both ends has a state in which the intermediate part is curved upwardly with respect to both end parts and the both end parts are curved. The bending is repeated periodically in a state where the intermediate portion is curved downward in a convex shape.

At this time, the distribution of the strain amplitude ε0 at the bending center of the crane girder 2 is as shown in FIG.

Further, the stress σ and strain ε acting on the crane girder 2 formed of a steel material having a high yield stress such as SS50 has a relationship as shown by the solid line in FIG.
Stress σ and strain ε acting on both damping members 8 and 9 formed of a steel material having a low yield stress such as S35 or an extremely mild steel material.
Have a relationship as shown by a chain line in FIG.

Therefore, as shown in FIG. 6, assuming that the stress σ acting on the crane girder 2 changes between points c and d where the stress is smaller than the yield points a and b of the crane girder 2, A stress exceeding the yield points e and f of the upper damping member 8 and the lower damping member 9 acts on the upper damping member 8 and the lower damping member 9 as the stress σ with respect to 2 increases, and occurs in the upper damping member 8 and the lower damping member 9. The strain ε changes between the yield point e, the point g, the yield point f, and the point h.

A range surrounded by a chain line connecting the yield point e, the point g, the yield point f, and the point h is the kinetic energy of flexure (absorption energy ΔE) absorbed by the upper damping member 8 and the lower damping member 9, Both the damping members 8 and 9 absorb the kinetic energy of the bending caused by the vertical vibration of the earthquake, so that the bending of the crane girder 2 is suppressed.

This absorbed energy ΔE is consumed as heat energy due to the elasto-plastic hysteresis of both damping members 8 and 9.

The above-mentioned upper damping member 8 and lower damping member 9
The respective absorbed energies ΔE1 are expressed by the following equation (1).

[0037]

## EQU1 ## ΔE1 = 4 {L (ε0-εy) ・ (σy × t × B)} (1) ε0: Strain amplitude of crane girder due to earthquake pitch εy: Yield strain of damping member σy: Yield stress of damping member L: damping member length B: damping member width t: damping member thickness

That is, the respective absorbed energies ΔE1 of the upper damping member 8 and the lower damping member 9 are
Can be adjusted by appropriately increasing or decreasing the width B and the thickness t of each.

Also, the upper damping member 8 and the lower damping member 9
The damping ratio H of the crane girder 2 to which is fixed is expressed by the following equation (2).

[0040]

[Equation 2] H = ΔE / 4πE (2) E: Kinetic energy acting on the crane girder and each damping member

That is, the damping ratio H of the crane girder 2 increases in proportion to the absorbed energy ΔE, which reduces the response acceleration of the crane girder 2.

As described above, in the overhead cranes shown in FIGS. 1 to 5, since the bending of the crane girder 2 caused by the vertical vibration of the earthquake can be effectively suppressed, the crane girder 2 is mounted on the girder rail 1. , 1 is not lifted, so that no impact force acts on the crane girder 2, the trolley 3 mounted on the crane girder 2, the beam 5 supporting the girder rail 1, and the like.

The upper damping member 8 and the lower damping member 9 are connected to the upper face plate 2b and the lower face plate 2c.
On the other hand, since they are fixed by the fillet weld 10 and the plug weld 11, the kinetic energy of the crane girder 2 is effectively transmitted to both the damping members 8 and 9.

The overhead crane of the present invention is not limited to the above-mentioned embodiment, and the upper damping member and the lower damping member are fixed to the crane girder by engaging means such as bolts. Of course, various changes can be made without departing from the scope of the present invention.

[0045]

As described above, the overhead crane of the present invention can exhibit various excellent effects as described below.

(1) In both the overhead crane according to claim 1 and claim 2 of the present invention, since the damping member absorbs the kinetic energy of the crane girder due to the vertical vibration of the earthquake and suppresses the bending, the girder is suppressed. The crane girder does not float up from the rail and the impact force does not act on the crane girder and trolley.

(2) In the overhead crane according to the second aspect of the present invention, since the damping member is fixed to the upper surface or the lower surface of the crane girder by fillet welding and plug welding, the kinetic energy of the crane girder is damped. Effectively transmitted to the member.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of an embodiment of an overhead crane of the present invention.

FIG. 2 is a view taken along the line II-II of FIG.

FIG. 3 is a view taken in the direction of arrows III-III in FIG. 1;

FIG. 4 is a view taken along the line IV-IV in FIG.

FIG. 5 is a view taken in the direction of arrows VV in FIG. 3;

FIG. 6 is a graph showing a relationship between stress and strain of the crane girder and the damping member shown in FIG.

FIG. 7 is a conceptual diagram showing an example of a conventional overhead crane.

FIG. 8 is a view on arrow VIII-VIII in FIG. 7.

FIG. 9 is a view taken in the direction of arrows IX-IX in FIG. 7;

[Explanation of symbols]

 1 rail for girder 2 crane girder 2b upper face plate (upper face of crane girder) 2c lower face plate (lower face of crane girder) 3 trolley 8 upper damping member 9 lower damping member 10 fillet welding 11 plug welding

Claims (2)

[Claims] 1. An overhead crane comprising: a crane girder horizontally moving along a girder rail; and a trolley mounted on the crane girder and horizontally moving in a direction orthogonal to the girder rail. An overhead crane, wherein a damping member made of a material having a yield stress lower than that of a material forming the crane girder is fixed to at least one of an upper surface and a lower surface of the crane girder. 2. The overhead crane according to claim 1, wherein the damping member is fixed to at least one of the upper surface of the crane girder and the lower surface of the crane girder by fillet welding and plug welding.