JPH08119571A - Steel tube for crane girder - Google Patents

Abstract

PURPOSE: To easily make the camber of a pair of girders uniform without any materials, labor or skill in the manufacturing process by providing a rib extending over the whole length along the inner wall on the side, and making a crane girder of a steel pipe located on the position to reinforce a guide rail of a hoist on the upper side of which the rib is fitted. CONSTITUTION: A girder 1 is made of a steel pipe 6 provided with a rib 5 extending over the whole length on the inner side on one upper side, and an electrically driven hoist 3 travels on rails 2 fixed on the upper outside wall surface of the rib 5. When a cargo is hoisted by a crane, the load is supported by the rib 5, and the strength against the buckling is increased because the rib 5 is on the compression side of the girder 1. The steel pipe 6 is integratedly manufactured by rolls, etc., and the constantly uniform camber can be obtained by constantly bending the steel pipe in the longitudinal direction. Thus, the camber of a pair of girders 1 can be easily made uniform without any material, labor or skill in the manufacturing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel pipe for a crane girder of a crane in which an electric hoist is guided and run on a pair of girders arranged in parallel with each other.

[0002]

2. Description of the Related Art Conventionally, a girder of a crane used for hoisting and carrying a relatively heavy object is usually formed of a thin tubular body. A rail for guiding the hoist is joined to the thin tubular body by welding or the like, and the hoist travels on the rail. In such gutters, the girder is usually pre-curved upward to prevent the girder from flexing downward when the load is hoisted. The current challenges with such girders are how to simplify the manufacturing process and how to reduce the weight of the girder.

When manufacturing a girder, an iron plate is cut into the shape of a flange material of the girder, the web material is cut into a state with an upwardly curved camber, and each of the flange material, the web material and the stiffener is cut. It was common to combine iron plates and assemble them by welding. Alternatively, after the girder is created, the girder is gradually bent while heating the girder, and the camber is applied to the girder, and the lower part of the girder is continuously welded. Then there was a method to add a camber.

[0004]

However, when manufactured by this method, the heat of welding causes distortion and twist of the girder, and residual stress is generated in the material, which causes welding cracks and the like. In addition, it requires a great deal of labor and materials such as cutting, assembling, and welding an iron plate, and also requires many skilled workers in manufacturing. The cambers of the pair of girders that were made were not easy to prepare, and it was necessary to heat the manufactured girders and gradually prepare the cambers so that the cambers were prepared, which required a lot of labor, skill, and materials.

[0005]

In order to solve the above problems, according to the present invention, a crane girder is provided with a rib extending over the entire length on the inner wall of one side, and the rib is on the upper side. It is composed of a steel pipe in a position to reinforce the rail.

[0006]

In this way, by consistently manufacturing a steel pipe in which ribs over the entire length are provided on the inner wall of one side on the upper side with the guide rail of the hoist, the flange material of the girder, the web material, and the inside of the girder are spaced at regular intervals. There is no need to cut steel materials such as stiffeners that are welded in the above, and to assemble and weld them. Then, by the integrated production, a constant camber can be created by curving the steel pipe in a constant arc shape in the length direction so that the upper side swells with a roll or the like. Then, when the steel pipes are arranged in parallel, a pair of camber-equipped girders can be manufactured easily. . In other words, this steel pipe can produce a crane girder that has no distortion due to welding or the like, has a uniform camber, has no stiffener, is light in weight, has a significantly reduced manufacturing process, and is inexpensive and has a short manufacturing time.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a case where a hoist 3 is guided and guided by a rail 2 on a pair of girders 1 arranged in parallel with each other, and both ends of these girders 1 are supported by a movable structure 4 usually called a saddle. There is.

FIG. 2 shows a side view of the girder 1 shown in FIG. 1, and FIG. 3 shows a sectional view taken along the line I--I of FIG. As can be seen from FIG. 3, the girder 1 is a steel pipe 6 provided with ribs 5 over the entire length inside one upper side.
The electric hoist 3 travels on the rail 2 which is configured by, and is fixed to the outer upper wall surface of the rib 5 by welding or the like. In addition, when making a normal steel pipe, an iron plate is bent as shown in FIG. 5 and a part thereof is welded. At this time, a part of the side is folded inward, and as shown in FIG. It will be 5. Further, as can be seen from FIG. 2, the girder 1 is provided with a camber.

When a load is usually hung by a crane, the load is lifted by the electric hoist 3, the load is transmitted through the wheels of the electric hoist 3, and is supported by the girder 1 from the rail 2. Conventionally, this load was supported by a web material or the like, but in this steel pipe, it is supported by ribs 5 provided over the entire length of the inner wall of the steel pipe. Further, since the rib 5 is on the compression side of the girder, the strength against buckling is increased.

In a crane in which an electric hoist is guided and run on a pair of girders arranged in parallel with each other, if the cambers of the pair of girders are not aligned and there is a difference in height, an electric hoist is generated. There is a risk that the lifting wire of No. 3 will be wound irregularly and the wire will be damaged or cut. However, a uniform camber can always be obtained by consistently manufacturing it with a roll or the like and by bending it in the length direction to a constant extent. Then, by imparting a certain moderate curvature to the girder with a roll or the like, a moderately large camber is given to a girder with a long span, and an appropriately small camber is naturally given to a girder with a short span. .

[0011]

As described above, in the steel pipe of the present invention, due to the effect of the ribs provided on the inner wall of the steel pipe, the steel pipe directly serves as the girder of the crane, the girder can be reduced in weight, and the steps for manufacturing the girder can be increased. It shortens and requires almost no material, labor, or skill in manufacturing. Then, by providing a certain curvature with a roll or the like, it is possible to easily align the cambers of the pair of girders in the crane formed of the pair of girders arranged in parallel.

[Brief description of drawings]

FIG. 1 is a perspective view of a crane.

FIG. 2 is a side view of the crane shown in FIG.

FIG. 3 is a cross-sectional view taken along line I-I of FIG.

FIG. 4 is an example in which a square steel pipe is changed to a round steel pipe.

FIG. 5 is a sectional view of a conventional steel pipe.

FIG. 6 is a sectional view of the steel pipe of the present invention.

[Explanation of symbols]

 1 ... Girder 2 ... Rail 3 ... Electric Hoist 4 ... Saddle 5 ... Rib 6 ... Steel Pipe 7 ... Weld

Claims (2)

[Claims] 1. A steel pipe in which a rib extending over the entire length is provided on an inner wall of one side of a square steel pipe. 2. A steel pipe in which the steel pipe is curved in an arc shape in a length direction by a roll or the like.