JPS5838333B2 - Lift arm for tilting cargo boxes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lift arm for tilting a cargo box in a dump mechanism.

Conventionally, various link-type dump mechanisms have been known as dump mechanisms used in dump trucks, etc., and most of them use a lift arm to tilt the cargo box, but this lift arm is generally of a welded sheet metal structure. It was constructed by welding together a large number of parts.

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, shortening fatigue life. Was.

In addition, since the welded joints of many parts suddenly change in cross section, stress concentration tends to occur, and there is also the problem of multiple problems such as cracking and failure.

The present invention aims to solve these problems, significantly reduce the number of parts to be welded, facilitate welding work, eliminate stress concentration points, and significantly extend fatigue life. The present invention is characterized by a press plate member having a through hole in the middle part and a substantially triangular outer circumferential part, which is pressed or molded into a saucer shape as a whole, and a substantially triangular shaped member that approximates the outer circumferential part. A planar plate member having an outer circumferential portion of be.

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

In FIG. 1, a dump truck is illustrated, and 1 is a loading box;
2 is the chassis frame, 3 is the rear wheel, 4 is the subframe, 5
is a link-type damping mechanism, which is interposed between the subframe 4 and the cargo box, and this damping mechanism 5 is a so-called gauze type, which includes a fluid pressure cylinder 6, a tension link 7, and a lift for tilting the cargo box. The lift arm 8 is composed of an arm 8, etc., and one end A of the lift arm 8 is pivotally connected to a part of the cargo box 1 by a shaft 9, and the other top B located farthest from the top A is connected to a pin 10. The remaining top C is connected to a hydraulic cylinder 6 by a crosshead shaft 11.
As shown in FIG.
When the hydraulic cylinder 6 extends and applies a force indicated by a vector F to the crosshead shaft 11, a tensile action is applied to the tension link 7 and a force indicated by a vector G is applied to the 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 points in the direction of this 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.

Therefore, the lift arms 8, 8 are connected to the hydraulic cylinder 6.
A pair of left and right lift arms 8 are arranged with a The arm 8 includes a press plate member 14, a flat plate member 15, and each top A,
The cylindrical bosses 16, 17, and 18 provided at B and C are integrally welded to each other, and other than that, no reinforcing plate pieces, reinforcing ribs, etc. are attached at all.

This press plate member 14 has an inner peripheral wall 20 forming a through hole 19 in the middle part, and a substantially triangular outer peripheral wall 21 in the outer peripheral part, and has a substantially uniform depth throughout. It is shaped like a tray with the same dimensions as a bracelet.

The bottom wall portion 22, which corresponds to the bottom surface of the tray, has a triangular ring shape with a punched middle portion, and an outer peripheral wall portion 21 is connected to the outer peripheral portion of the bottom wall portion 22 in a bent shape at a right angle. The inner peripheral wall 20 is connected to the inner peripheral part of the bottom wall 22 in a bent shape at right angles, and the cross-sectional shape of the press plate member 14 has two U-shapes as shown in FIG. Depending on the traversal position, it has a U-shape.

Next, the plane plate member 15 has a substantially triangular outer circumference 23 that approximates the outer circumference of the press plate member 14.
is welded 25 to the inner surface near the edge 24 of the outer peripheral wall portion 21 of the press plate member 14, thereby forming the outer peripheral portion 23 of the flat plate member 15.
and the wall portion 21 of the outer peripheral portion of the press plate member 14 are integrally welded to each other.

Furthermore, as is clear from FIG. 4, the height of the inner circumferential wall 20 of the tray-shaped press plate member 14 is set slightly smaller than the height of the outer circumferential wall 21. The inner peripheral edge 26 of the press plate member 14 and the flat plate member 15 are welded 27 so as to be in contact with the side surface of the flat plate member 15 at right angles.
It is constructed by connecting and integrating the

Here, the shape of the through-hole portion 19 can be freely deformed, and the number of the through-hole portions 19 can be made plural, but in order to avoid stress concentration points on the lift arm 8, the shape of the through-hole portion 19 is curved without corners as shown in FIG. In addition, the distance N between the inner circumferential wall 20 and the outer circumferential wall 21 is set to be small to a certain extent so that when an external force is applied to the lift arm 8, the drawing board members 14 and 15 can bear the force integrally with each other. In addition, in order to make the section modulus of each cross section of the lift arm 8 into a dog, and the strength to be a dog, it is necessary to set this interval dimension N to a certain degree,
Therefore, the above-mentioned interval dimension N is determined from both the weight and strength of the lift arm 8 as a whole, but as is clear from FIG. 1, compressive stress is generated on the longest side 28, causing buckling. For ease of use, it is preferable to set the above-mentioned interval dimension N on the longest side 28 larger than the other sides, and increase it to the dimension P as shown by the imaginary lines in FIGS. 2 and 4. , B, C cylindrical bosses 16, 1718 are:
It is inserted into a hole formed through both plate members 1415 in a continuous manner according to its outer diameter, and is integrated by welding 29. 9,
The pin 10 crosshead shaft 11 is inserted, and the vector H,
External forces indicated by G and F are transmitted from each boss 16, 17, 18 to both plate members 14, 15 which are integrally connected by welding 29...

Note that, except for the holes into which the cylindrical bosses 16, 17, and 18 are inserted, the planar plate member 15 has no through-holes at all, as shown in FIGS. 2 and 4. As shown in the figure,
For the purpose of weight reduction, a through hole 30 is provided in the middle part of this flat plate member 15 to create a press plate member 14 shaped like a tray.
It is also preferable that the flat plate member 15 is fitted in a disc-like manner between the inner circumferential wall portion 20 and the outer circumferential wall portion 21 and integrated by welding 25, 27L.

Alternatively, although not shown, from the shape of FIG.
It is also possible to form a through hole in the flat plate member 15, or to form this through hole in advance in the flat plate member 15 separately.

Next, as shown in FIG. 6, the inner peripheral wall 2 of the press plate member 14 is
0, with its inner peripheral edge bent further inward at a right angle,
It is also possible to form it into an L-shape, as shown in Figure 7.

The height dimensions of the inner and outer circumferential walls 20 and 21 of the press plate member 14 are the same, and the husband end edges 26 and 24 are both fixed to the flat plate member 1.
Welding 27.25L on one side of the flat plate member 15 allows the outer peripheral part 23 of the flat plate member 15 to protrude from the outer peripheral wall part 21.

Therefore, a symmetrical pair of lift arms 8, 8 as described above is used in the damping mechanism 5 of (2), but in the present invention, the flat plate member 15 is interposed with a fluid pressure cylinder 6. The crosshead can be disposed on the inside as shown in Fig. 8 or on the outside as shown in Fig. 9. reducing the bending stress acting on the shaft 11, and
This can prevent the left and right lift arms 8, 8 from falling or twisting.

In other words, as is clear from the comparison between FIG. 8 and FIG. 9, assuming that the inner distance S of the lift arms 8 and 8 is the same in order to avoid interference with the cylinder 6, the actual neutral plane distance is: 132>1, so if a concentrated load F were to act on the center of the crosshead shaft 11, the bending moment diagram would be a triangle as shown in Figures 8 and 9. , the maximum bending moment in Fig. 8 is
M1El, E
l, 21, and the moment in Figure 9 is M2'44, and l2>l1, so M2>M,
In this way, it can be said that it is reasonable and preferable in terms of strength to arrange the flat plate member 15.15 on the inside and the press plate member 14.14 on the outside.

It should be noted that the present invention is free to make design changes other than the above-mentioned embodiments, and the dump mechanism 5 used for tilting the cargo box may be configured such that the pivot axis of the tension link 7 and the pivot axis of the fluid pressure cylinder 6 are mutually connected. Different link structures may be used, or the dump mechanism 5 may include a lift arm 8 pivotally attached to the subframe 4 side, or a pair of left and right lift arms 8, 8 may be used. The dump mechanism may include multiple pairs of.

Further, the pair of left and right lift arms 8, 8 may be integrally connected by a connecting rod, a connecting shaft, etc., and may have a structure that cannot be separated.

The present invention is constructed as described in detail above, and has effectively achieved its intended purpose.

In particular, the number of parts before welding is minimized, making inventory of parts easier, easier processing, and significant labor savings in welding work.

Furthermore, the lift arm 8 is subjected to significant bending stress, torsional stress, etc. due to the large external force caused by the load in the cargo box 1, the thrust force of the fluid pressure cylinder 6, and the tensile force of the tension link 7. This reduces the number of welded areas where stress concentration is likely to occur and where cracks can occur, thereby effectively preventing crack failures and significantly extending the towing fatigue life.

Furthermore, since the through-hole portion 19 is formed by removing the middle portion of the press plate member 14, which is close to the neutral axis in terms of strength and does not contribute much to an increase in the section modulus, the weight is reduced, and furthermore, the weight is reduced. By welding 27 the plate members 14 and 15 at the inner circumferential edge 26 of the through-hole portion 19, they can be completely connected and integrated, resulting in a structure that is strong against bending and twisting.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of a dump mechanism, FIG. 2 is a side view showing an embodiment of the present invention, and FIG. 3 is a partially sectional plan view.
Figure 4 is a sectional view taken along line DD in Figure 2, Figures 5, 6, and 7.
The figures are cross-sectional views showing different embodiments, and FIGS. 8 and 9 are views showing the arrangement of the left and right lift arms and the bending moment. 5... Dump mechanism, 8... Lift arm, 14... Press plate member, 15...
Plane plate member, 19... Through hole portion, 23...
...Outer periphery, 25...Welding, 26...
Inner peripheral edge, 27...Welding.

Claims (1)

[Claims] 1. A pressed plate member having a through-hole in the middle part and a substantially triangular outer circumferential part, the whole being press-shaped into a tray shape, and a flat plate member having a substantially triangular outer circumferential part approximating the outer circumferential part. A lift for tilting a cargo box, characterized in that the two are connected and integrated by welding both outer circumferential parts to each other and welding the inner circumferential edge of the through-hole part to the intermediate part of the flat plate member. arm.