JPS6228020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lift arm for tilting a cargo box in a dump mechanism.

[Conventional technology and its problems]

Conventionally, various link types have been known as dump mechanisms used in dump trucks, etc.
Most of them have a lift arm to tilt the cargo box, but this lift arm is generally of a welded sheet metal structure, and is made up of a large number of parts welded together. For example, press plate members, angles, and channels were welded together, and reinforcing plate pieces were welded to each part to further improve strength. As a result, there are a large number of welding points, which makes welding work cumbersome and difficult to manufacture.The thermal stress caused by welding tends to cause deviations in product dimensions.Furthermore, welded seams are prone to cracking, which increases fatigue life. was shortened. Furthermore, since the cross-sections of welded joints of many parts change suddenly, stress concentration is likely to occur, and cracks are also likely to occur. Another problem was that it was heavy compared to its strength, and it was difficult to automate welding.

The present invention solves these problems, significantly reduces the number of parts to be welded, facilitates or automates welding work, eliminates stress concentration points, significantly extends fatigue life, and reduces weight. The purpose is to also achieve this goal.

[Means for solving problems]

The present invention provides a lift arm having a generally triangular side surface and a cylindrical boss disposed at each top of the triangle, in which the inner plate member and the outer plate member are separated sufficiently from the outer peripheral edge of the substantially triangular shape. The inner plate member and the outer plate member are welded together in a multi-layered manner at the intermediate portion thereof, and the inner plate member and the outer plate member are further separated at a sufficient interval along the outer periphery, and a continuous hollow is formed along the outer periphery. The reinforcing portion is formed in an encircling shape by the inner plate member and the outer plate member, and is located at a position having a predetermined distance from the outer circumferential wall of the hollow reinforcing portion and also from the inner circumferential wall of the hollow reinforcing portion. Cylindrical bosses are inserted through the hollow reinforcing portion and fixed at positions having predetermined intervals.

[Effect]

Since both the inner and outer plate members are brought into contact and welded in a multi-layered manner at the middle portion sufficiently far from the outer peripheral edge of the substantially triangular shape, the welding work is easy to perform and no welding distortion occurs. Furthermore, since the cylindrical boss is inserted into the hollow reinforcing portion with a predetermined interval between the outer circumferential wall portion and the inner circumferential wall portion, the cylindrical boss does not fall down due to external force, which is advantageous in terms of strength. In addition, the strength and durability near the corner apex where the greatest strength and durability are required are significantly increased.

〔Example〕

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

In Fig. 1, a dump truck is illustrated, 1 is a cargo box, 2 is a chassis frame, 3 is a rear wheel, 4 is a subframe, and 5 is a link type dump mechanism.
It is interposed between the subframe 4 and the cargo box 1, and in this example, a gauze type is shown as the dump mechanism 5, which is composed of a fluid pressure cylinder 6, a tension link 7, a lift arm 8 for tilting the cargo box, etc. , the entire side surface shape of the lift arm 8 is approximately triangular,
One top A is pivotally connected to a part of the packing box 1 by a shaft 9, the other top B located farthest from this one top A is pivotally connected to a tension link 7 by a pin 10, and the remaining The top C is pivotally connected to the piston rod 12 of the hydraulic cylinder 6 at the crosshead shaft 11, and as shown in FIG. Link 7 has a tensile action and applies a force indicated by vector G to pin 10. Since the other ends of the fluid pressure cylinder 6 and the tension link 7 are pivotally connected to the same trunnion shaft 13, the vector H acting on the shaft 9 is directed toward the trunnion shaft 13, and as a result, the lift Three vectors F, G, and H act on the arm 8, and it serves as a lever member for lifting the cargo box 1, so to speak.

The lift arms 8, 8 are arranged in pairs on the left and right with the fluid pressure cylinder 6 interposed therebetween, and FIGS. 2, 3, and 4 show the left lift arm 8, and the right one is symmetrical. Therefore, although not shown in the drawings, each lift arm 8 has a generally triangular side surface shape as shown in FIG.
Cylindrical bosses 16, 17, and 18 are provided at C, and the shaft 9, pin 10, and crosshead shaft 11 are inserted through them, respectively.

Further, the lift arm 8 includes an inner plate member 15, an outer plate member 14, and cylindrical bosses 1 at each top portion A, B, and C.
6, 17, and 18 are integrally welded together, and the structure has an extremely small number of component parts, with no reinforcing pieces, reinforcing ribs, etc. attached thereto. In the illustrated example, the outer panel member 14 is made by bending the outer periphery of a plate-shaped material cut in a substantially triangular shape inwardly, and protruding the central portion so as to protrude inwardly.
Made by press molding. In addition, a through hole 19 of an appropriate size is formed in the convex portion 31 which is raised inwardly in this way. Therefore, the outer panel member 14
has a continuous outer circumferential wall portion 21 forming an outer circumferential edge 32 of the lift arm 8, and an inner circumferential wall portion 20 forming an inner circumferential surface of the convex portion 31;
A convex inner wall portion 33 is formed by bending the inner edge of the inner circumferential wall portion 20 at a right angle. The above-mentioned hole 19 is
A case in which the shape is smaller than the inner circumferential wall portion 20 and follows the inner circumferential wall portion 20 is illustrated. Therefore, the inner wall portion 33 of the convex portion is left in the form of an annular band in the specific example.

On the other hand, the inner plate member 15 is a single flat plate,
A substantially triangular shape corresponding to the inner surface of the outer peripheral edge 32 is cut from a plate-shaped material.

Then, as shown in FIG. 4, the inner plate member 15 and the outer plate member 14 are overlapped from both the inner and outer sides, and the continuous hollow reinforcing portion 34 is surrounded along the substantially triangular outer peripheral edge 32 of the lift arm 8. It is formed into.
That is, the inner surface of the outer circumferential wall 21 of the outer plate member 14 and the outer circumferential portion 23 of the inner plate member 15 are welded 25, and the inner wall 33 of the convex portion 31 of the outer plate member 14 and the intermediate portion of the inner plate member 15 are welded together. Weld the parts together in a layered manner 27
Then, the hollow reinforcing portion 34 is attached to the outer peripheral edge 32 of the lift arm.
It is formed into a ring shape along the In this way, the inner weld 27 is performed at an intermediate portion sufficiently distant from the substantially triangular outer peripheral edge 32.

Furthermore, as is clear from FIGS. 2 and 3, in the hollow reinforcing portion 34, the inner circumferential wall portion 20 and the outer circumferential wall portion 2
The cylindrical bosses 16, 17, 1 of each of the top parts A, B, and C are placed at predetermined intervals K ₁ , K ₂ , K ₃ .
8 are fixed respectively. That is, welding 29, 29
The cylindrical bosses 16, 17, 18 are connected and integrated with the inner and outer plate members 15, 14, respectively. Each boss 16, 17, 18 has the shaft 9, pin 10,
When the shaft 11 is inserted, the external forces indicated by vectors H, G, and F are applied to the welding 29 from each boss 16, 17, and 18.
... is transmitted to the inner and outer plate members 15 and 14 which are integrally connected.

By the way, the shape of the through hole portion 19 can be freely deformed, and it is also preferable to make it circular, oval, etc.
It is also possible to make the size smaller by using a plurality of them. It is desirable that the lift arm 8 has a curved shape with no corners as shown in FIG. 2 so that there are no stress concentration points. Furthermore, the distance between the inner circumferential wall 20 and the outer circumferential wall 21, that is, the width N of the cross section on each side of the hollow reinforcing portion 34 is determined by In order to increase the strength by increasing the section modulus of each cross section of the lift arm 8, it is necessary to set the width dimension N to a certain degree large so that the lift arm 8 can absorb the force integrally. can be,
Therefore, the width dimension N is determined from both the weight and strength of the lift arm 8 as a whole. As is clear from FIG. 1, compressive stress is generated on the longest side 28, which tends to cause buckling. Setting it large is
It is extremely reasonable and preferable in terms of strength.

It should be noted that the present invention is of course free to change the design in addition to the above-described embodiments, and the dump mechanism 5 used for tilting the cargo box may include a pivot shaft of the tension link 7 and a pivot shaft of the fluid pressure cylinder 6. It is also possible to adopt a link structure in which the attachment shaft is located at a different position, or to have a link mechanism in which the link mechanism is folded forward instead of backward as shown in FIG. Or lift arm 8 on the subframe 4 side.
It is also possible to use an inverted dump mechanism that is pivotally mounted. Or a pair of left and right lift arms 8, 8
The dump mechanism may include a plurality of pairs of the left and right lift arms 8, 8, and the left and right lift arms 8, 8 are integrally connected in a left and right bridge manner by a connecting rod, a connecting shaft, etc.
You are free to make it an indivisible structure.

〔Effect of the invention〕

The present invention is configured as described in detail above, and has the following significant effects.

Welding of the intermediate portion sufficiently far away from the outer peripheral edge 32 is easy because both the inner and outer plate members 15 and 14 are brought into contact with each other in a multi-layered manner, the welding process is easy, there is little welding distortion, and the lift arm can be formed into an accurate shape. It can be manufactured.

Since the cylindrical bosses 16, 17, and 18 are fixed to the outer circumferential wall 21 at a predetermined distance K ₁ . Therefore, the fatigue strength is extremely high.

Since the cylindrical bosses 16, 17, 18 are fixed at predetermined intervals K ₂ , K _{3 . .} . from the inner circumferential wall 20, the inner circumferential wall 20 is prevented from cracking due to fatigue.

The cylindrical bosses 16, 17, and 18 form the hollow reinforcing portion 34.
Since it is fixed as a through-hole, the strength and durability near the tops A, B, and C, where the highest strength and durability are required, are tremendous. and cylindrical boss 16,1
7 and 18 are prevented from being damaged in the direction of falling down due to external force.

The weight can be reduced by using a thin plate material, and hollow reinforcing parts with high strength and rigidity can be cleverly formed in a continuous manner along the outer periphery, which contributes the most to strength and rigidity.

The number of parts is small.

In the lift arm, where compressive stress, tensile stress, and torsional stress act in a complex manner, we formed a hollow reinforcing part with high strength and rigidity along the outer periphery, which contributes the most to strength and rigidity, so that it can be made from thin plate material. Despite its light weight, a structure with extremely high strength and rigidity was obtained.

By forming the hollow reinforcement part continuously,
There are no stress concentration areas or weld deterioration areas, and the fatigue strength when the cargo box is repeatedly tilted and dumped is excellent.

[Brief explanation of the drawing]

Figure 1 is a side view showing an example of the dump mechanism, Figure 2 is a side view showing an example of the dump mechanism.
The figure is a side view showing one embodiment of the present invention, FIG. 3 is a partially sectional plan view, and FIG. 4 is a sectional view taken along line DD in FIG. 2. A, B, C...Top, 8...Lift arm, 1
4, 15... Plate member, 16, 17, 18... Cylindrical boss, 27... Welding, 32... Outer periphery, 34...
Hollow reinforcement part, K ₁ , K ₂ , K ₃ ... spacing.

Claims (1)

[Scope of Claims] 1. In a lift arm whose overall side surface shape is approximately triangular and in which cylindrical bosses 16, 17, and 18 are arranged at each of the apexes A, B, and C of the triangle, an inner plate member 15 and The outer plate member 14 is welded together in a layered manner at an intermediate portion sufficiently far away from the substantially triangular outer circumferential edge 32, and the inner plate member 15 and outer plate member 14 are welded together along the outer circumferential edge 32. A continuous hollow reinforcing portion 34 is connected to the inner plate member 15 and the outer plate member 1 along the outer peripheral edge 32 so as to be separated from each other at sufficient intervals.
4 in an encircling shape, and is located at a predetermined distance K ₁ from the outer peripheral wall 21 of the hollow reinforcing portion 34 and at a predetermined distance from the inner peripheral wall 20 of the hollow reinforcing portion 34. A lift arm for tilting a cargo box, characterized in that cylindrical bosses 16, 17, 18 are fixed at positions having K ₂ , K ₃ . . . through the hollow reinforcing portion 34.