JP2000255996A - Tilt stay structure for forklift mast - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a high stress as low as possible to prevent a crack being generated in a high stress part to damage a mast by generation of the high stress in a tilt stay welding end part of a rail of an outer mast, in a stress confirming test for cargo receiving, rear side tilting on a base, and the like for carrying out welding to a high bending stress end part of the outer mast, in a tilt stay for attaching a tilt cylinder for tilting a forklift mast frontwards and rearwards, although one in which generation of stress concentration is divided exists already. SOLUTION: In this tilt stay structure for a forklift mast, a width dimension (b) for weld-attaching a tilt stay 1 welded to a back plate 3 of a rail of an outer mast is made sufficiently narrow with respect to a width dimension B of the back plate 3, a vertical dimension (h) is made long, its shape is formed into a shape provided with a weldable slot 4 in the central part of the width dimension (b), a welding end part 5 is arranged in the vicinity of a neutral axis of a rail benbing stress, a welding length is made long, and a welding leg length is made short.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt stay welding structure for mounting a tilt cylinder for tilting a mast of a forklift forward and backward.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Patent Publication No. 8-562 is used.
No. 7 discloses a forklift tilt cylinder mounting structure, etc., in which a plate or bracket with a devised shape is welded from the center to the end of the back plate of the outer mast rail, and a tilt cylinder capable of tilting the mast back and forth is mounted. It is shown.

[0003]

However, even in the above-described conventional welding mounting structure, the occurrence of severe stress concentration is divided, but since the outer mast is welded to the end having a high bending stress, unloading and loading are required. In the stress confirmation test such as upward and backward tilting, high stress is generated at the weld toe on the end side of the outer mast rail by the tilt stay, and cracks are generated and propagated in the high stress portion, and the mast is broken. The challenge is to keep this high stress as low as possible.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the width of a tilt stay to be welded to a back plate of a rail of an outer mast is set to the width of the back plate. The width is sufficiently narrow, the top and bottom dimensions are long, and a long hole that can be welded is provided at the center of the width, and the weld toe is located near the neutral axis of the rail bending stress. At the same time, the forklift mast has a tilt stay structure with a longer welding length and a shorter welding leg length.

With the above structure, when bending stress is applied to the mast rail due to unloading of the mast or the like, the welding toe of the tilt stay can be finished so that the welding ends at a position near the neutral axis of the bending stress of the rail. Because of the arrangement of
High stress due to the combination of the bending stress and the weld toe is not generated, and the stress reduction effect can be largely reduced to about half, so that the outer mast is not broken.

[0006] Further, by increasing the welding length, the mounting strength can be maintained and the welding leg length can be shortened, so that the deformation of the outer mast due to welding is reduced and the number of correction steps is reduced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a side view showing an embodiment of a one tilt stay welding structure according to the present invention, and FIG. 2 is a perspective view. In the drawing, the shape of the tilt stay 1 to be welded to the back plate 3 of the outer mast rail 2 is such that the weld mounting width dimension b of the tilt stay 1 is sufficiently narrowed with respect to the width dimension B of the back plate 3, and The length h is made longer, and a long hole 4 is provided at the center of the width dimension b.

In welding the tilt stay 1 having this shape,
Bending stress is applied to the mast rail 2 by unloading, etc.
Even if a high stress occurs at both ends of the width of the width, the welding is finished near the neutral axis where the bending stress is low, and the welding of the tilt stay 1 is not extended to near the both ends. The stress concentration due to the combination of the weld toe 5 and the high stress of the rail 2 is small, and the stress is dispersed.

In the conventional welding mounting structure shown in FIG. 5, although the division is made for the occurrence of severe stress concentration, the outer mast rail 2 is welded to the end of the back plate 3 having high bending stress. Since residual stress remains, when a stress confirmation test such as unloading and tilting backward on the table is performed, high stress is also generated at the weld toe 5 of the tilt stay 1 on the end side of the outer mast rail 2, Cracks are formed in the stressed part, and the outer mast is damaged due to growth.

Further, the tilt stay 1 of the present invention has a shape in which the elongated hole 4 is provided in the central portion of the width dimension b, and the total welding length can be increased, so that the welding leg length can be suppressed short. . Therefore, deformation of the outer mast due to welding is reduced, and the number of correction steps after welding is reduced.

FIG. 3 shows a comparison of the stresses. In the case where the tilt stay 1 according to the present invention is attached by welding, the state of occurrence of stress at the weld toe 5 is about half that of the conventional one. Has become. In other words, by keeping the weld toe 5 close to the neutral axis where the value of the bending stress generated on the back plate 3 of the rail 2 due to the mast unloading is low, complicated stress is prevented from being concentrated and dispersed. It shows that the effect is appearing.

[Brief description of the drawings]

FIG. 1 is a side view of a tilt stay according to the present invention.

FIG. 2 is a perspective view of a tilt stay.

FIG. 3 is a stress comparison diagram of a weld toe.

FIG. 4 is a side view of the forklift.

FIG. 5 is a side view of a conventional tilt stay.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tilt stay b Width dimension h Vertical dimension 2 Rail 3 Back plate B Width dimension 4 Slotted hole 5 Welding force toe

Claims (1)

[Claims] In a tilt stay for mounting a tilt cylinder for tilting a forklift mast back and forth, a width (b) of a tilt stay (1) to be welded to a back plate (3) of a rail (2) of an outer mast, The width (B) of the back plate (3) is sufficiently narrow, the upper and lower dimensions (h) are longer, and a long hole (4) that can be welded is provided at the center of the width (b). Tilt stay structure of a forklift mast characterized in that it has a shape, the weld toe (5) is located near the neutral axis of the bending stress of the rail (2), and the weld length is increased and the weld leg length is reduced. .