JPH09295794A - Load hoisting device for telescopic boom type crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the durability of a boom by preventing the boom from being curved to the utmost when the tip end part of the boom is liable to be curved by loads while the loads are hoisted up by the telescopic boom of a crane. SOLUTION: One to several top pendant sheaves 5 are provided for an upper part above a top sheave 4 provided for the tip end part of a boom 1 composed of a multi-step cylinder, and one to several tail pendant sheaves 6 are also provided for an upper part at the base end part side of the boom 1. While a detour part 10 to be installed between each top pendant sheave 5 and each tail pendant sheave 6, is being disposed at the intermecliate part of a pendant rope 8 pulled out of a drum 7, the pendant rope is run around a hook block 9 through the top sheave 4 from the tail pendant sheave 6 on which the end part of the detour part 10 is hanged, and the top end of the pendant rope 8 is thereby fixedly attached to the top end part of the boom 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a boom that can be expanded and contracted by a multi-stage cylinder, as provided in a hydraulic mobile crane among mobile cranes, and that expands and contracts to reduce a bending moment applied to the boom during unloading. The present invention relates to a lifting device for a crane.

[0002]

2. Description of the Related Art A boom of a hydraulic mobile crane is constructed of a multi-stage cylinder as is well known, and a pendant rope unwound from a drum provided in the hydraulic mobile crane is provided on an upper surface of a base of the boom. The guide sheave is hung on the sheave of the main hook block through the top sheave provided at the tip of the boom, and the tip of the pendant rope is fixed to the rope socket provided at the tip of the boom. The longer you can,
A pendant rope is hung vertically between the top sheave and the sheave of the main hook block with a fixed pulley and a movable pulley structure.

[0003]

By the way, a boom of this kind is one in which the base part is fixed by a pin so that it can swing up and down, and is undulated up and down by a hydraulic cylinder. Since a bending moment is applied to the boom by the boom, it bends within the elastic limit even if it is used for hoisting within the allowable load range. When the clamshell is attached, the earth and sand are grabbed and transported to another place, and when the clamshell is opened in the air and the earth and sand are discharged, the load of the boom is removed all at once and the phenomenon that the clamshell rises is seen. From this, it can be clearly seen that the boom is bent by the load. If it is said that bending and distraction are repeated in this way, metal fatigue will occur during long-term use, and eventually a part of the boom will deform or break under permanent strain, resulting in an accident. However, there is an increasing demand for booms that extend more than 30 m in particular, but there is a problem that the longer the boom, the greater the curvature of curvature and the higher the rate of failure.

The present invention is particularly applicable to telescopic booms, even when the booms are extended to the maximum extent or extended to the midway of the boom, the lifting force opposite to the lifted load. The above problem is solved by suppressing the bending action of the boom.

[0005]

SUMMARY OF THE INVENTION A solution of the present invention is to provide one to several top pendant sheaves above a top sheave provided at a tip portion of a boom composed of a multi-stage cylinder, and to provide a boom base end portion. One to several tail pendant sheaves are provided on the upper side of the side, and a detour portion for interposing between the top pendant sheave and the tail pendant sheave is interposed in the middle portion of the pendant rope pulled out from the drum, and a terminal end portion of the detour portion. It is characterized in that the tail pendant sheave that is hung on is hooked around the hook block through the top sheave, and the tip of the pendant rope is fixed to the tip of the boom.

Another solution is to hang the pendant rope differently. The pendant rope pulled out from the drum is hung around the hook block through the top sheave, and the top of the pendant rope is reached between the hook blocks. It is characterized in that a circumvention portion is provided between the pendant sheave and the tail pendant sheave, and the tip of the pendant rope passing through the circumvention portion is fixed near the tail pendant sheave.

Further, it is preferable to provide the tail pendant sheave on a cylinder standing upright from a support.

[0008]

[Function] As described above, by providing the detour between the pendant rope and the tail pendant sheave, when the pendant rope is wound around the drum and the load is lifted, the detour pendant rope is provided at the tip of the boom. Since a force that pulls the top pendant sheave toward the base end side of the boom is generated, as the direction in which the pulling force acts greatly upward with respect to the boom, the force is applied to the tip of the boom as a lifting force, It is possible to suppress bending.

The above-mentioned solution means is one in which a detour is provided on the pendant rope and then it is hung on the hook block.
Another solution is to hang the pendant rope first on the hook block and then to provide a detour. According to this solution, the moving pulley of the hook block reduces the load applied to the moving pulley by half the load. Tension is applied to the detour part, and the tension is applied as a force to lift the boom tip to suppress the bending of the boom, and when the load is hoisted and unloaded, the boom is hoisted without bending. Since the descending operation is performed while maintaining the state, it is possible to stabilize the descending operation.

Further, if the tail pendant sheave is attached to a cylinder that moves up and down, the angle formed by the detour section with the boom can be increased, and thus the bending of the boom can be greatly suppressed. In addition, this type of boom is often attached to the vehicle in general, but in the case of a mobile type like this, by lowering the cylinder, the total height of the vehicle can be lowered and the traveling safety can be improved. It is also advantageous in securing

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention is a crane having a multi-stage cylinder and carrying a telescopic boom, and the existing crane has a main pendant rope and an auxiliary pendant rope. However, the present invention is primarily directed to main pendant ropes.

At the tip of the boom, a top pendant sheave is provided in addition to the existing top sheave, a tail pendant sheave is provided at the base end of the boom, and the pendant rope pulled out from the drum provided on the support is attached to the boom. From the top pendant sheave at the tip end and the tail pendant sheave provided on the base end side of the boom, through the detour part hung between the top sheave and the hook block,
The tip of the pendant rope is fixed to the tip of the boom.

Moreover, the top pendant sheave and the tail pendant sheave are provided above the upper surface of the boom. Particularly, the boom base end side portion on which the tail pendant sheave is provided is the boom base end or the boom. The tail pendant sheave may be provided on a support provided with a boom such as a vehicle body of a crane truck around the base end portion of, and it is preferable to provide the tail pendant sheave at a position as high as possible above the boom. The angle formed between the pendant rope of the section and the boom is increased, and the lifting force on the boom tip is increased.

In still another embodiment, the boom is provided with the top pendant sheave and the tail pendant sheave as described above, and the pendant rope is first hung on the hook block and then the detour is made between the top pendant sheave and the tail pendant sheave. The end of the pendant rope is fixed to the vicinity of the tail pendant sheave through the section.

In each of the above embodiments, the tail pendant sheave is provided on the cylinder standing upright from the support provided on the boom.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 3, the prefabricated boom 1 is composed of a multi-stage cylinder, has a hoisting cylinder 2, has a guide sheave 3 at the base end of the boom 1, and has a top sheave 4 at the tip thereof. However, the top pendant sheave 5 is provided above the top sheave 4 at the tip of the boom 1, and the tail pendant sheave 6 is attached above the guide sheave 3 at the base end of the boom 1.

Therefore, the pendant rope 8 drawn out from the drum 7 around which the main pendant rope is wound is hung around the top pendant sheave 5 at the boom tip end through the guide sheave 3 at the boom base end, and the base end of the boom 1 is laid. The tail pendant sheave 6 is guided around the lower part of the boom, and further guided toward the tip of the boom 1. The pendant rope 8 is hung from the boom 1 through the top sheave 4, and hung on the hook block 9 having a movable pulley. The tip of the pendant rope 8 is fixed to the boom 1.

As described above, the pendant rope 8 is stretched, but the guide sheave 3 to the top pendant sheave 5,
The portion between the tail pendant sheave 6 and the top sheave 4 is referred to as a detour section 10. This detour section 10 is provided on the upper side of the boom 1. Especially, the tail pendant sheave 6 should be provided at a position as high as possible. preferable.

When the above-mentioned hoisting device is provided on a mobile crane, the top pendant sheave 5 and the tail pendant sheave 6 shown in FIG. The frame 11 for holding the tail pendant sheave 6 is provided so that it can be tilted from the standing state toward the rear of the mobile crane (the direction opposite to the tip side of the boom 1).

The frame 11 for holding the tail pendant sheave 6 is not limited to the base end portion of the boom 1,
As shown in FIG. 2, it is preferable to provide the support 12 to which the boom 1 is attached, and a mobile crane, if it is a mobile crane.

When the boom 1 is extended and a load is suspended, the load W is applied to the tip of the boom 1, but in the conventional case, the tip of the boom 1 bends downward as shown by the dotted line in FIG. To do. However, since the detour 10 is provided on the pendant rope 8 as in the present invention, the force W for attracting the top pendant sheave 5 to the tail pendant sheave 6 is applied to the detour 10 by the load W applied to the tip of the boom 1. An equivalent pulling force P is applied, and the pulling force P acts on a pressure Q for compressing the boom 1 and a force R for lifting the boom 1 upward. Due to this lifting force R, the bending of the boom 1 is applied to the boom 1. Depending on the magnitude of the applied load, it can be suppressed significantly or almost.

Next, the second embodiment will be described with reference to FIG. 4 and FIG. 5 with respect to the same members as those in the above-mentioned embodiment and only the different parts will be described. At least one pair of pendant sheaves 5 are coaxially provided, and a pendant rope 8 pulled out from a drum 7 is hung down via one top sheave 4 to hook block 9.
Around the movable sheave of No. 3, and then pull it up and hang it on one of the top pendant sheaves 5 through the other top sheave 4.
Next, it is hung around the tail pendant sheave 6 and then further hung around the other top pendant sheave 5 and fastened to the clip 13 provided near the tail pendant sheave 6. It is provided. In addition, three Toppe pendant sheaves 5,
By providing two tail pendant sheaves 6, the detour section 10 can be double hung.

Further, in the first embodiment, the tail pendant sheave 6 is provided on the frame 11 standing upright from the support body 12 using the vehicle body of the mobile crane as the support body 12 as shown in FIG. The frame 11 is replaced with the cylinder 14 and is attached to a member that moves up and down in the cylinder 14. Further, the clip 13 may be attached similarly.

According to the second embodiment, it is the same as in the first embodiment that the load applied to the tip of the boom 1 by the detour 10 is reduced to half to substantially reduce the curvature of curvature. For example, in the case of the first embodiment, when the load is hoisted and then unloaded, there occurs a phenomenon in which the tip of the boom 1 bends slightly but slightly downward. However, when the second embodiment is tested, the tip end of the pendant rope 8 is fixed to the base end side of the boom 1, so that when the suspended load is unloaded, the boom 1 vertically vibrates and descends in a pulsating manner. It is possible to smoothly descend in an extremely stable state without any problem.

Although the above causes cannot be grasped with certainty mechanically, as a result of experiments, in the case of the first embodiment,
When the load is unloaded, the hook block 9 is hung from the drum 7 via the bypass portion 10. Therefore, when the drum 7 is reversed and the hook block 9 is lowered, the tension of the bypass portion 10 is relaxed, so that the boom 1 This seems to be due to the relaxation of the tension. However, in the second embodiment, when the drum 7 is reversed and the hook block 9 is lowered, the hook block 9 is directly lowered and the detour 10 is kept in a tensioned state, so that the boom 1 does not move. You can lower the load as it is.

[0026]

According to the hoisting device for the telescopic boom type crane according to the present invention, the pendant rope is provided with the detour portion between the top pendant sheave and the tail pendant sheave, so that a load is applied to the boom. When
A pulling force acts on the bypass part toward the base end side of the boom, and a lifting force is generated at the boom tip as a component of the pulling force.Therefore, this lifting force suppresses the bending of the boom and reduces the load. Although it varies depending on the size, the degree of bending is greatly reduced compared to the conventional case, and the durability of the boom can be significantly increased.

In addition, a pendant rope pulled out from the drum is hung on a hook block, then hung between a top pendant sheave and a tail pendant sheave, and a detour section is provided in which the tip of the pendant rope is fixed near the tail pendant sheave. In that case, the upward pulling force acts on the tip of the boom, and the degree of bending can be significantly reduced, and when descending from the suspended state,
The tip of the boom will not vibrate up and down, and you can unload it in a stable state.

Further, if the tail pendant sheave is attached to the movable portion of the cylinder standing upright from the support, the tail pendant sheave can be set at a high position and the pulling force on the boom can be further increased. . Further, when moving on a general road, the height can be lowered, and the vehicle can be moved without any trouble.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of a hoisting device for a telescopic boom type crane according to the present invention.

FIG. 2 is a side view showing a similar example of a hoisting device for a telescopic boom crane.

FIG. 3 is an explanatory diagram showing an action of generating a lifting force with respect to a load.

FIG. 4 is a side view showing a second embodiment of the hoisting device for a telescopic boom crane according to the present invention.

FIG. 5 is an explanatory view showing how to hang a pendant rope of the second embodiment.

[Explanation of symbols]

 1 Boom 3 Guide Sheave 4 Top Sheave 5 Top Pendant Sheave 6 Tail Pendant Sheave 7 Drum 8 Pendant Rope 9 Hook Block 10 Detour 12 Support 14 Cylinder

Claims (3)

[Claims] 1. An upper portion of a top sheave (4) provided at a tip portion of a boom (1) comprising a multistage cylinder.
To several top pendant sheaves (5) are provided, and one to several tail pendant sheaves (6) are provided above the base end side of the boom (1), and the pendant rope (7) is pulled out from the drum (7). In the middle part of 8), there is a detour part (10) which is laid between the top pendant sheave (5) and the tail pendant sheave (6), and the tail pendant sheave (which hangs the end part of the detour part (10) is laid. The telescopic boom type crane characterized in that the end of the pendant rope (8) is fastened to the end of the boom (1) by being hung around the hook block (9) from 6) through the top sheave (4). Lifting device. 2. An upper part of a top sheave (4) provided at the tip of a boom (1) comprising a multi-stage cylinder.
To several top pendant sheaves (5) are provided, and one to several tail pendant sheaves (6) are provided above the base end side of the boom (1), and the pendant rope (7) is pulled out from the drum (7). 8) Top sheave (4)
A circumvention part (10) which is hung between the top pendant sheave (5) and the tail pendant sheave (6) while being hung around the hook block (9) via the pendant rope (8). A hoisting device for a telescopic boom crane, characterized in that the tip of a pendant rope (8) passing through a detour (10) is fixed near the tail pendant sheave (6). 3. The tail pendant sheave (6),
The hoisting device for a telescopic boom crane according to claim 1 or 2, wherein the hoisting device is provided on a cylinder (14) standing upright from a support (12).