JPH024516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for detecting overload of cargo being lifted by a crane, and particularly to an overload detection device that takes into account variations in the dead weight of the jib of the crane.

[Prior Art] Generally, for cranes, etc., the rated lifting load is determined based on the crane's mechanical strength and overturning stability, and according to the undulation angle (or working radius) of the crane's jib.

However, in conventional overload detection devices for cranes, the jib's heave angle is detected and a rated load signal (load due to the jib and cargo) corresponding to the jib's heave angle is generated from a so-called rated load curve memory section. By comparing the rated load signal with a signal corresponding to the actually measured lifting load, an overload condition is detected and an alarm device is activated.

By the way, with a crane, tension is generated in the rope supporting the jib due to the hanging load and the jib's own weight, but when the length of the jib is changed depending on the work conditions,
Alternatively, when the jib is replaced due to the end of its service life, the weight of the jib may change due to the weight tolerance of the pipe materials constituting the jib or variations in the amount of welding of the pipes. Therefore, the overload detection device, which detects whether or not there is an overload based on the rated load calculated in advance and the measured load for both the jib and the cargo, has extremely poor accuracy in detecting the alarm point for the load due to the actual cargo. There is a problem.

[Objective of the Invention] The object of the present invention is to correct the dispersion between the pre-calculated value and the actual measured value of the jib of the crane, and to detect overload with extremely high accuracy of the warning point due to the overload of the load due to the actual cargo. The goal is to provide equipment.

[Structure of the Invention] According to the present invention, in an overload detection device for detecting an overload of a crane, the When comparing the tension with the second tension determined for each luffing angle or working radius of the jib based on the actually measured jib own weight and the measured load, it is necessary to The deviation of the third tension determined for each heave angle or working radius of the jib from the fourth tension determined for each heave angle or working radius is detected only by the measured jib self-weight, and the deviation is determined based on the deviation. Either the first tension or the second tension is corrected, and after the correction, if the second tension becomes larger than the first tension, an overload condition is detected and an alarm is issued. A crane overload detection device is obtained.

[Examples of the Invention] The present invention will be described below based on Examples. First, a crane 1 to which an overload detection device according to the present invention is applied will be described with reference to FIG. 3 is the basic jib 3a
By combining the joint jibs 3b, a plurality of the joint jibs 3b can be replaced. A hoisting winch 15 and an elevating winch 16 are disposed approximately at the center of the upper revolving body 2, and a mast 17 is attached to the rear of the upper revolving body 2.

The hoisting rope 5 let out from the hoisting winch 15 passes through pulleys 18 and 1 attached to the tip of the jib 3.
The hook 20 is hung around a pulley 20a of the hook 20 via the hook 9, and is connected to the tip of the jib 3.

The elevating rope 21 let out from the elevating winch 16 is wrapped around a bail 22 pivotally attached to the top of the mast 17 and a bridle 23 attached to the other end of the pendant rope 4, one end of which is attached to the tip of the jib 3. is connected to the other end of the load detector 7 attached to the upper revolving body 2.

Furthermore, an angle detector 11 is attached to the base end of the jib 3 to detect the jib angle.

A load 6 is suspended from the hook 20, and the load 6 can be raised or lowered by winding up or lowering the hoisting rope 5. Further, the jib 3 can be rotated in the horizontal direction by the rotation of the upper revolving structure 2, and the jib 3 can change the heave angle θ by winding and unwinding the elevating rope 21. Therefore, when the load is not suspended, a tension (moment) corresponding to the heave angle θ due to the weight of the jib 3 is applied to the elevating rope 21, and when the load 6 is suspended, the weight of the jib 3 and the load 6 are A tension corresponding to the undulation angle θ due to the weight is applied to the elevating rope 21.

In such a crane 1, if the moment applied to the jib 3 (that is, the tension applied to the elevating rope 4) is too large, the crane will fall or break. The rated load of the cargo 6 that can be lifted by the crane is determined in advance, and when using the crane, the load of the cargo 6 must be below the rated weight. This rated load is generally determined by a so-called rated load curve corresponding to each undulation angle. That is, if the undulation angle θ is known, the value of the load that can be lifted can be known.

Next, referring also to FIG. 2, an overload detection device according to the present invention will be explained.

The load detector 7 described above is connected to the comparison section 91 of the calculation comparison section 9 and the first storage section 10 via the switching section 8 . Further, the angle detector 11 is connected to the first storage section 1.
0, the second storage section 12 and the third storage section 13. These first, second, and third storage units 10, 12, and 13 are connected to the calculation unit 92 of the calculation comparison unit 9.
The comparison unit 91 is further connected to the alarm 14 .

The switching unit 8 switches and connects the load detector 7 to the first storage unit 10 and the comparison unit 91. By operating the switching unit 8, the load detector 7 and the first storage unit 10 are connected to each other.
Jib 3 of crane 1 shown in Figure 1 by connecting
jib 3 with no load 6 lifted.
If the heave angle θ is changed, the tension (F ₁ ) applied to the elevation rope 21 will be
(fourth tension) can be measured by the load detector 7, and this can be measured as the first load signal (F ₁ ) in the first storage unit 1.
0, and the first storage unit 10 stores, for example, the relationship between the undulation angle θ and the tension F ₁ as shown in FIG. ).

In the second storage unit 12, a standard value of the tension due to the self-weight according to the heave angle θ of the standard jib 3 is calculated and input in advance. That is, the relationship between the tension due to the jib's own weight (third tension) and the undulation angle of the jib under the crane design conditions is input. (Hereinafter, this tension will be referred to as a standard value. For example, the information shown in FIG. 3b is input). The third storage unit 13 also stores the standard value and the heave angle θ of the jib 3 of the crane 1.
(or working radius), the total value of tension (F ₃ ) due to the maximum allowable load (hereinafter referred to as rated load) that can be lifted (hereinafter simply referred to as first tension =
This is called rated tension. ) is input and stored (for example, the information shown in Fig. 3c is input).Next, the load 6 is hoisted onto the jib 3 of the crane 1, and the switching unit 8 is operated to perform calculation comparison with the load detector 7. The comparing section 91 of section 9 is connected. Therefore, the load detector 7 detects the heave angle θ (or working radius) of the jib 3.
Correspondingly, the tension (F ₄ ) applied to the elevation rope 21
(second tension) is measured and input to the comparator 91 as the second load signal (F ₄ ).

At this time, the heave angle θ of the jib 3 is measured by the angle detector 11, and the angle signal (θ) of this angle detector 11 is stored in the first, second, and third storage units 10, 12 as shown in the figure. and 13, each storage unit 1
0, 12, and 13, the tension F ₁ corresponding to this angle signal, that is, the heave angle θ of the jib 3,
F ₂ and F ₃ are sent to the calculation unit 92 as third, fourth, and fifth load signals, respectively.

The calculation unit 92 first subtracts (F 1 −F ₂ ) between the tension (F ₁ ) of the elevation rope 21 due to the weight of the jib 3 of the actual machine and the tension (F ₂ ) represented by the quasi-value of the jib ₃ . That is, the deviation (correction value) between the tension F ₁ and the tension (F ₂ ) is investigated. Furthermore, the calculation section 9
In step 2, the calculation shown in the first equation below is performed, that is, the correction value (F ₁ -F ₂ ) is added from the rated tension (F ₃ ).

F ₅ = F ₃ + (F ₁ − F ₂ ) ...(1) As is clear from the first equation, if F ₁ = F ₂ , the rated tension (F ₃ ) can be applied to this crane. , if F ₁ <F ₂ , only a tension smaller than the rated tension (F ₃ ) can be applied. Also F ₁ >
If F ₂ , a tension greater than the rated tension (F ₃ ) can be applied.

The comparison section 91 has the tension (F ₅ ) expressed by the first equation.
A sixth load signal corresponding to the above is input, the measured tension F ₄ and the tension (F ₅ ) are compared, and when the relationship shown by equation (2) is satisfied, an alarm signal is sent to the alarm 14. do.

F ₄ ≧ F ₃ + (F ₁ − F ₂ ) ...(2) In this way, no matter what type of jib is installed, the tension applied to the crane is compared by comparing the tension due to the jib's own weight with the standard value. Since the allowable maximum load, that is, the total value (maximum load due to the jib's own weight and cargo) is corrected, it is possible to suppress variations in the alarm point (actual suspended load amount that issues an alarm) due to variations in the jib's own weight, etc., and the alarm point The accuracy can be improved.

FIG. 4 shows another embodiment according to the invention.

In this embodiment, as shown in the figure, the output from the switching section 8 is connected to the first storage section 10 and the calculation section 92, and the output from the third storage section 13 is connected to the comparator 92. This is different from the embodiment shown in FIG. Therefore,
In the embodiment shown in FIG. 4, the calculator 92 calculates F ₅ =F ₄ -(F ₁ -F ₂ )...(3), and the comparator 92 corresponds to the tension (F ₅ ) shown by the third equation. A sixth load signal is input, and the rated tension (F ₃ ) is compared with the tension (F ₅ ), and the following fourth equation F ₃ ≦F ₄ −(F ₁ −F ₂ ) ……(4 The only difference is that an alarm signal is issued to the alarm device 14 when the relationship shown in ) is established.

[Effects of the Invention] As explained above, in the present invention, the tension due to the actual weight of the jib attached to a crane etc. is corrected by the tension due to the predetermined jib weight.
Furthermore, by correcting the predetermined tension (rated tension) due to the jib's own weight and cargo that are applied to the crane, and issuing an alarm based on the tension based on the corrected jib's own weight and cargo, the alarm point can be minimized. It can be determined with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an example of a crane in which the overload detection device according to the present invention is used, and FIG.
The figure is a block diagram showing the overload detection device according to the present invention, and Figures 3a, b, and c are the undulation angles and tensions stored in the first, second, and third storage sections shown in Figure 2, respectively. FIG. 4 is a block diagram showing another embodiment of the overload detection device according to the present invention. 1... Crane, 2... Upper revolving structure, 3... Jib, 3a... Basic jib, joint jib, 4... Pendant rope, 5... Hoisting rope, 6... Luggage, 7
... Load detector, 8 ... Switching section, 9 ... Calculation comparison section, 10 ... First storage section, 11 ... Angle detector,
12...Second storage unit, 13...Third storage unit, 14
... Alarm, 15 ... Hoisting winch, 16 ... Elevation winch, 17 ... Mast, 21 ... Elevation rope, 22 ... Bail, 23 ... Bridle.

Claims (1)

[Claims] 1.Equipped with an upper revolving body and a jib pivotally attached to the revolving body so as to be able to move up and down, the jib can be replaced in multiple numbers by a combination of a basic jib and a joint jib, and the luffing angle of the jib is detected. An angle detector to
In a crane having a load detector that detects the tension of an elevating rope for elevating and elevating the jib, a first tension determined for each luffing angle or working radius of the jib based on the predetermined jib own weight and rated load. and the second tension determined for each luffing angle or working radius of the jib based on the actual jib own weight and the measured load determined by actual measurements. The deviation of the third tension, which is determined for each undulation angle or working radius, from the fourth tension, which is determined for each undulation angle or working radius, is detected only by the measured jib own weight, and The present invention has means for correcting either the first tension or the second tension, and detecting an overload condition and issuing an alarm when the second tension becomes larger than the first tension after the correction. A crane overload detection device featuring: