JP2000191286A - Sensing method and device for actual load of crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten the sensing accuracy by correcting an error of actual load originating from a change in the component of the own weight of boom caused by an additional weight, etc. SOLUTION: The total load and boom angle measured by a load sensor 8 and a boom angle sensor 9 are entered into a calculating means 12. On the basis of the measurements, the calculating means 12 determines the component of the own weight of the boom among the total load and the actual load acting by a suspension load and adds a corrective value in which a change in the component of the own weight of the boom caused by additional weight, etc., is taken, into account, to the calculation value of the actual load when a correction start signal is fed by a correction start switch 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting an actual load acting on a boom due to a suspended load in a crane having a boom that can be raised and lowered.

[0002]

2. Description of the Related Art The prior art will be described with reference to a so-called mechanical crawler crane having a lattice boom, which is a preferred embodiment of the present invention.

[0003] This type of crane is equipped with an overload prevention device for preventing overturning and the like, and a rated total load WR is set for each work radius determined by the boom angle and the boom length to reduce the tension of the boom hoisting rope. The actual load (the load acting on the suspended load) WA is obtained by subtracting the boom's own weight component acting on the boom's own weight from the measured value (total load) of the load sensor to be detected. In order to recognize whether or not the crane is operating, when the actual load exceeds the rated total load WR, an overload prevention process such as crane operation stop is performed.

Conventionally, the actual load WA is obtained by dividing a load sensitivity δ by a value obtained by subtracting a boom own weight component F0 from a boom hoisting rope tension F (hereinafter referred to as a boom hoisting tension) representing a total load.

That is, the moment balance of the general mechanical crane shown in FIG.

[0006]

(Equation 1)

[0007]

In FIG. 2, reference numeral 1 denotes a crane main body, 2 denotes a boom mounted on the crane main body 1 so as to be able to move up and down,
Are boom foot pins, which serve as the fulcrum of this boom 2;
Is a boom hoisting rope for raising and lowering the boom 2, 4 is a guy cable for transmitting the hoisting force of the boom hoisting rope 3 to the boom 2, 5 is a hoisting rope for raising and lowering the suspended load W, and 6 is a hoisting drive for the rope 5. The winch drum 7 is a hanging hook.

A load sensor 8 for detecting a tension F of the boom hoist rope 3 and a boom angle sensor 9 for detecting a boom angle θ are provided as measuring means.

In FIG. 2 and Equation 1, T: tension of the hoisting rope 5 WA: actual load due to the suspended load WB: boom own weight f: distance between the boom foot pin P and the boom undulation line (moment of the boom undulation line) Arm) t: distance between the boom foot pin P and the hoisting line (moment arm of the hoisting line) a: horizontal distance between the boom foot pin P and the suspended load W (moment arm of the suspended load W) b: boom foot pin P The horizontal distance of the boom center of gravity Q (the moment arm of the boom's own weight).

When the above equation 1 is arranged for the boom hoisting tension F, the following equation is obtained.

[0012]

(Equation 2)

In Equation 2,

[0014]

(Equation 3)

And solving for the actual load WA,

[0016]

(Equation 4)

## EQU1 ## Equation 4 is a principle equation for obtaining the actual load WA from the boom hoisting tension F.

In equation (4), F0 denotes the boom self-weight component of the boom hoisting tension F (boom hoisting tension when no load is applied) δ: load sensitivity (boom hoisting tension per unit load), and the boom angle (or working radius), respectively. ) Is stored in the overload prevention device as an arithmetic expression that changes according to (1). In practice, it is often set by the following approximate expression using the boom angle θ as a variable.

[0019]

(Equation 5)

[0020]

(Equation 6)

Although F0 and δ are represented by linear expressions with respect to the boom angle θ, they may be approximate expressions that are quadratic or more. If the expression cannot be expressed by an equation, a data table may be stored in advance (intermediate data is interpolated), and a value corresponding to the boom angle θ may be read.

[0022]

As described above, conventionally,
Since the actual load WA is obtained with the boom's own weight component being constant and invariable, it is not possible to cope with a change in the boom's own weight component.

For example, when an additional weight such as a scaffold or a signboard is attached to the boom 2, the actual load value is merely mechanically calculated from a previously stored arithmetic expression, despite the increase in the boom's own weight component. Absent. Therefore, as a result, a value larger than the actually suspended load is calculated and displayed as the actual load WA.

In particular, when the suspension load is small, in the calculation formula for obtaining the actual load, the boom own weight component subtracted from the boom hoisting tension F becomes large, so that there is a problem that the detection accuracy of the actual load deteriorates.

Accordingly, the present invention provides a method and apparatus for detecting an actual load of a crane, which can correct the deviation of the actual load due to the change in the weight component of the boom and improve the detection accuracy.

[0026]

According to a first aspect of the present invention, there is provided a method for detecting an actual load, comprising the steps of:
The boom's own weight component acting by the boom's own weight and the actual load acting by the hanging load of the total load are obtained by calculation, and the calculated value of the actual load is corrected in consideration of the variation of the boom's own weight component due to added weight and the like. Is added.

According to a second aspect of the present invention, there is provided a crane provided with an up-and-down boom, (i) a boom angle measuring means for measuring a boom angle, and (ii) a load measuring means for measuring a total load. (Iii) Based on the measured boom angle and total load, the boom own weight component acting by the boom own weight of the total load, and the actual load acting by the hanging load are calculated, and the calculated value of the actual load is calculated. And a calculating means for performing a correction in consideration of a variation of the boom's own weight component due to an additional weight or the like.

According to a third aspect of the present invention, in the configuration of the second aspect, the calculation means is configured to obtain a correction value in consideration of a variation of the boom's own weight component due to an additional weight or the like as a variable that varies with the boom angle. Things.

According to a fourth aspect of the present invention, in the configuration of the third aspect, the calculating means obtains a correction value in consideration of a variation of the boom's own weight component due to the added weight, assuming that the added weight acts at the position of the center of gravity of the boom. It is constituted in.

According to a fifth aspect of the present invention, in the configuration of the third aspect, the calculating means obtains a correction value in consideration of a variation of the boom's own weight component due to the added weight, assuming that the added weight acts at a position other than the position of the boom center of gravity. It is configured as follows.

According to a sixth aspect of the present invention, in the configuration according to any one of the second to fifth aspects, the calculating means obtains correction values at a plurality of boom angles, and performs an interpolation operation using the obtained plurality of correction values. Thus, a correction value at another boom angle is obtained.

According to a seventh aspect of the present invention, in the configuration according to any one of the second to sixth aspects, the calculating means sets an allowable range in advance for the correction value, and the correction value obtained by the calculation exceeds the allowable range. Is configured not to execute the correction.

According to the above method and apparatus, if there is a change in the boom's own weight component due to the added weight or the like, the boom's own weight component can be accurately grasped by adding a correction according to this change to increase the detection accuracy of the actual load. Can be.

Here, according to the constitutions of claims 3 to 5, since the correction value changes in accordance with the change in the boom angle, it is effective especially when the correction is relatively large with respect to the change in the boom angle.

In this case, according to the fourth and fifth aspects,
When there is an additional weight due to the attachment of a scaffold or a signboard to the boom, the correction value can be converted as being on the boom center of gravity (Claim 4) or not (Claim 5). , The accuracy of detecting the actual load can be further improved.

On the other hand, when the position of the load acting due to the added weight cannot be specified, for example, a correction value is obtained at a plurality of boom angles, and the correction value between the boom angles is calculated by interpolation. Therefore, high detection accuracy can be maintained.

Further, according to the configuration of the seventh aspect, an allowable range is set for the correction value, and if the correction value exceeds this allowable range, no correction is performed, so that the correction is performed arbitrarily by the operator. No adverse effects such as impairment of the overload prevention function occur.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an actual load detecting device according to an embodiment of the present invention includes a load sensor 8 for detecting a boom hoisting tension, a boom angle sensor 9 for detecting a boom angle, and a boom angle sensor 9 for detecting a boom angle. It comprises a controller 10 to which detection signals from both sensors 8 and 9 are input, and a correction start switch 11 for supplying a correction start signal to the controller 10.

Further, the controller 10 includes a calculating means 12 for calculating an actual load as described below, and a display unit 13 for displaying the calculated actual load to an operator on a CRT screen or the like. .

The calculating means 12 has a storage unit 14, and performs the actual load calculation and the correction calculation of each of the following embodiments based on the storage contents of the storage unit 14 and the measured values of the sensors 8 and 9.

First Embodiment In FIG. 2, when the hanging hook 7 is lowered on the ground, the tension value measured by the load sensor 8 is only the boom's own weight component. The actual load indicated by 13 should be 0.0 ton.

However, if the boom 2 has an additional weight such as a scaffold, a signboard or the like, the actual load is calculated and displayed larger by subtracting only the boom's own weight component stored in advance.

Therefore, the calculation formula for calculating the actual load is expressed by the following equation (7). When the correction start switch 11 is operated and the correction start signal is input to the calculation means 12, the calculation result becomes 0.0 ton. A correction value α is determined.

[0044]

(Equation 7)

By setting the correction value α as a fixed value and uniformly subtracting (or adding) the change in the boom angle θ, the actual load WA taking into account the fluctuation of the boom's own weight component due to the added weight is obtained. Determined at the boom angle.

Second Embodiment If the deviation of the actual load is small and the correction is performed within the error range, the first
Although there is no problem with the method in which the correction value α is a fixed value as in the embodiment, the detection value of the added weight is actually affected by the change in the boom angle. Needs to be a variable according to the change in the boom angle.

Therefore, the calculation formula for calculating the actual load is given by equation 8, and the correction value α is determined so that the calculation result when the correction start signal is input becomes 0.0 ton.

[0048]

(Equation 8)

Then, the correction value β is set to the boom own weight component F.
The coefficient multiplied by 0 is uniformly multiplied (or divided) according to the change in the boom angle.

Third Embodiment If the characteristic of the correction value for the change in the boom angle is the same as the characteristic of the arithmetic expression for calculating the boom's own weight component, there is no problem with the above equation (8). When conversion cannot be performed in Q) of FIG. 2 (for example, when the additional weight is only at the tip of the boom), it is necessary to set a unique calculation formula for the boom change in the correction value.

Therefore, the calculation formula for calculating the actual load WA is expressed by equation (9), and the correction value β is determined so that the calculation result at the time when the correction start signal is input becomes 0.0 ton.

[0052]

(Equation 9)

Then, the correction value β is uniformly multiplied (or divided) according to a change in the boom angle as a coefficient to be applied to the correction operation formula.

Although the equation for calculating the correction value α is represented by a linear expression of the boom angle θ, it may be an approximate expression that is higher than a quadratic expression.

If the value cannot be expressed by an equation, the data may be stored in advance in the storage unit 14 (interpolation calculation is performed between data), and the value corresponding to the boom angle θ may be read.

Fourth Embodiment If the position of the added weight is known or can be predicted, it can be dealt with by the above equations 7 to 9, but otherwise the setting itself is difficult, so that the influence on the boom angle change is completely absorbed. Can not.

In view of this, a plurality of correction settings are made, and the accuracy is improved by matching.

In this case, any one of Equations 7 to 9 can be used, but Equation 8 will be described as an example.

First, a correction start signal is input at a certain boom angle θ1, and the actual load WA is set to 0.0 ton. That is,

[0060]

(Equation 10)

In the cylinder angle θ1, WA
= 'Is determined so that = 0.0.

Next, when the boom angle is changed to another angle θ2, if the actual load WA according to the above equation (10) is not 0.0 ton, a correction start signal is input again, and in the equation (10), the correction of the boom angle θ2 is performed. Sometimes, a correction value β ″ that satisfies WA = 0.0 ton is obtained.

Therefore, the correction value is set as an interpolation correction value that changes from β ′ to β ″ as the boom angles θ1 to θ2 change.

The arithmetic expression and the interpolation expression of the correction value are as follows:
Becomes

[0065]

[Equation 11]

Then, the correction value γ according to the change in the boom angle θ is uniformly multiplied (or divided) as a coefficient applied to the boom own weight component F0.

By the way, if the correction can be made in any state and in any case at the discretion of the operator, the value can be forcibly adjusted (for example, even if the sensor fails, the adjustment can be forcibly performed). The load prevention function may be impaired.

Therefore, in order to keep the correction within the fine adjustment range, the correction range by the calculating means 12 is limited, for example, the correction possible range is within ± 1.0 ton. If the correction range is exceeded, the correction is executed. It is desirable to process so that it does not.

Other Embodiments (1) In the above embodiment, a mechanical crawler crane is taken as an example. However, a tower crane (a tower boom of a crane body is attached, and a jib can be raised and lowered at the tip of the tower boom. Can be applied to the crane mounted on the ground.

Here, in the case of an ordinary tower crane in which the tower boom is fixed at a fixed angle, each correction value is calculated from an arithmetic expression accompanying a change in the jib angle or a data table.

On the other hand, even in the case of a tower crane in which the tower boom also rises and falls, each correction value is calculated for each tower boom angle from an arithmetic expression or a data table accompanying a change in the jib angle.

The present invention can be applied not only to the crawler type crane described in the above embodiment but also to a wheel type crane. The present invention is not limited to a crane provided with a lattice boom, but provided with a box-shaped telescopic boom. It can also be applied to cranes.

In the case of a crane with a box-shaped telescopic boom, the boom length changes, and it is necessary to add this as a calculation parameter.

(2) In the above embodiment, the condition at the time of setting is 0.0 ton. However, the adjustment condition when only the hanging hook 7 is lifted (for example, 3.0 ton), or when the reference load is lifted. Adjustment conditions (for example, 10.0
ton) is also possible.

(3) In order to prevent an erroneous setting due to an erroneous operation, it is desirable to provide an interlock function such as accepting the start of correction only when the correction start switch 11 is kept pressed for a certain period of time.

(4) In the above embodiment, the case where the actual load WA is calculated and displayed to be larger than the actually suspended load due to the influence of the added weight and the like has been described. However, the actual load WA may be calculated and displayed smaller than the actual load in some cases.

For example, the storage unit 14 of the controller 10
In some cases, the additional weight is already taken into account (added) as the boom's own weight component stored in advance. In this case, when working with the standard boom (without additional weight), the actual load W
A is calculated small and displayed.

According to the present invention, even in such a case, correction can be made by judging whether the weight is the added weight of the minus component. In this case, α in Equations 7 to 9 is a negative value.

[0079]

As described above, according to the present invention, if there is a change in the boom's own weight component due to the added weight or the like, the boom's own weight component is accurately grasped by adding a correction according to this change, and the actual load of the boom is reduced. Detection accuracy can be improved.

Here, according to the third to fifth aspects of the present invention, since the correction value changes in accordance with the change in the boom angle, it is particularly effective when the correction is relatively large with respect to the change in the boom angle.

In this case, according to the fourth and fifth aspects of the invention,
When there is an additional weight due to the attachment of a scaffold or a signboard to the boom, the correction value can be converted as being on the boom center of gravity (Claim 4) or not (Claim 5). , The accuracy of detecting the actual load can be further improved.

On the other hand, according to the invention of claim 6, for example, when the position of the load acting due to the added weight cannot be specified, a correction value is obtained at a plurality of boom angles, and the correction value between the boom angles is calculated by interpolation. Therefore, high detection accuracy can be maintained.

According to the seventh aspect of the present invention, an allowable range is set for the correction value, and when the correction value exceeds the allowable range, no correction is performed, so that the correction is performed arbitrarily by the operator. No adverse effects such as impairment of the overload prevention function occur.

[Brief description of the drawings]

FIG. 1 is a block configuration diagram of an actual load detection device according to an embodiment of the present invention.

FIG. 2 is a schematic side view of a crawler crane provided with a lattice boom according to a preferred embodiment of the present invention.

[Explanation of symbols]

 2 Boom 3 Boom hoisting rope 4 Guy cable 5 Hoisting rope W Hanging load 8 Load sensor (Load measuring means) 9 Boom angle sensor (Boom angle measuring means) 11 Correction start switch 10 Controller 12 Computing means 14 Storage unit of computing means 13 Display

Claims (7)

[Claims] Claims: 1. A crane with an undulating boom, based on the total load and boom angle measured.
The boom's own weight component acting by the boom's own weight and the actual load acting by the suspension load of the total load are obtained by calculation, and the calculated value of the actual load is corrected in consideration of the variation of the boom's own weight component due to added weight and the like. A method for detecting the actual load of a crane, characterized by adding 2. A crane provided with a boom that can be raised and lowered, wherein: (i) boom angle measuring means for measuring a boom angle; (ii) load measuring means for measuring a total load; Based on the total load, of the total load, the boom own weight component acting on the boom own weight and the actual load acting on the suspension load are obtained by calculation, and the calculated value of the actual load is calculated based on the variation of the boom own weight component due to the added weight and the like. An actual load detecting device for a crane, comprising a calculating means for performing a correction in consideration of the following. 3. The actual load detecting device for a crane according to claim 2, wherein the calculating means is configured to obtain a correction value in consideration of a variation of the boom's own weight component due to an additional weight or the like as a variable that varies depending on the boom angle. An actual load detection device for a crane. 4. The actual load detecting device for a crane according to claim 3, wherein the calculating means obtains a correction value in consideration of a variation of the boom's own weight component due to the additional weight, assuming that the additional weight acts on the position of the center of gravity of the boom. An actual load detection device for a crane, wherein the device is configured as described above. 5. The actual load detecting device for a crane according to claim 3, wherein the calculating means sets a correction value in consideration of a variation of the boom's own weight component due to the additional weight, assuming that the additional weight acts at a position other than the position of the center of gravity of the boom. An actual load detection device for a crane, characterized in that it is configured to determine the actual load. 6. The actual load detecting device for a crane according to claim 2, wherein the calculating means obtains correction values at a plurality of boom angles and uses the obtained correction values. An actual load detecting device for a crane, wherein a correction value at another boom angle is obtained by interpolation calculation. 7. The actual load detecting device for a crane according to claim 2, wherein the calculating means sets an allowable range in advance for the correction value, and the correction value obtained by the calculation determines the allowable range. An actual load detection device for a crane, characterized in that the correction is not executed if the load exceeds the load.