JPH0422838B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an overload detection device for detecting overload of cargo being lifted by a crane.

(Prior art) Generally, the rated lifting load (limit load) of a crane is determined based on the crane's mechanical strength and overturning stability, and according to the crane boom's undulation angle (or working radius). .

By the way, in the conventional overload detection device,
Memorize the tension of the support rope supporting the boom (T _a ) for the rated lifting load (W _a ) corresponding to the crane boom's heave angle and the tension of the support rope due to the boom's own weight (T _p ), and then When the load is lifted, the tension (T) of the support rope due to this load is detected, and the load of the load (actual load (W)) is calculated using equation (1).
is calculated and overload is detected.

W = T - T _p / T _a - T _p × W _a ...(1) Generally, an overload detection device uses a boom angle detector to detect the boom's heave angle and detects the tension of the support rope that supports the boom. The boom angle detector and boom tension detector respectively convert the detected luffing angle and tension into voltage, amplify it, and send it to a computer etc. Then, the actual load of the lifted cargo is calculated. Therefore, the amplifier sections of the boom angle detector and the boom tension detector need to have accurate zero adjustment and gain adjustment (also called span adjustment).

Through this zero adjustment and span adjustment, the output voltages of the boom angle detector and the boom tension detector can always be made to correspond to the load being lifted, regardless of the characteristics (individual differences) of each crane. Therefore, the zero adjustment and span adjustment of the amplifier section greatly affect the load detection accuracy.

Here, zero adjustment and span adjustment in a conventional overload detection device will be outlined.

First, the boom is set horizontally, that is, the undulation angle is set to zero, and the zero adjustment variable resistor is adjusted so that the output voltage of the amplifier section of the boom angle detector becomes zero. Next, lower the boom to the ground, set the tension of the support rope to zero, and adjust the zero adjustment variable resistor so that the output voltage of the amplifier section of the boom tension detector becomes zero.

Furthermore, with the boom angle set at a predetermined angle,
The span adjustment variable resistor is adjusted so that the output voltage of the boom angle detector amplifier section becomes a predetermined value. Similarly, a load with a known load is suspended on the boom, and the span adjustment variable resistor is adjusted so that the output voltage of the boom tension detector amplifier becomes a predetermined value.

(Problems to be Solved by the Invention) However, in the conventional overload detection device, the zero adjustment and span adjustment of the amplifier sections of the boom angle detector and tension detector are performed by variable resistors.
There is a problem in that a measuring instrument is required for adjustment, and furthermore, adjustment requires skill. Furthermore, considering the individual differences between cranes, zero adjustment and span adjustment must be performed for each crane, which is extremely troublesome, and as mentioned above, since a variable resistor is used, there are problems in terms of reliability. be.

Furthermore, the boom must be manipulated in various ways (in particular, the boom must be lowered to the ground), and zero adjustment and span adjustment are extremely troublesome.

(Means for Solving the Problems) The present invention provides a crane that is equipped with a boom whose one end is pivotally connected to a revolving body and whose other end is supported by a support wire rope, and which suspends cargo using the boom. The overload detection device used for detecting an overload of the crane includes a boom angle detection unit for detecting the heave angle of the boom as a detected heave angle, and a support force for detecting the support force applied to the support wire rope. a boom support force detection unit for detecting force; a limit load (Wa) of the crane according to the undulation angle; a first boom support force applied to the support wire rope by the limit load and the boom's own weight; (Ta) and the second boom supporting force (T ₀ ) applied to the support wire rope by the boom's own weight are stored, and the zero adjustment coefficient and gain (T 0 ) in the boom angle detection section are stored. span) adjustment coefficients as a first zero adjustment coefficient and a first gain adjustment coefficient, respectively;
a second storage unit for storing a zero adjustment coefficient and a gain (span) adjustment coefficient in the boom supporting force detection unit as a second zero adjustment coefficient and a second gain adjustment coefficient, respectively; a calculation unit for calculating the zero adjustment coefficient of No. 2 and the first and second gain adjustment coefficients, as well as calculating the actual load of the cargo lifted by the boom, and for the calculation unit; and a mode setting section that switches between a setting mode that specifies calculation of the first and second zero adjustment coefficients and the first and second gain adjustment coefficients, and a normal mode that specifies calculation of the actual load. The calculation unit is given first and second boom radii (R ₁ , R ₂ ) by the boom when the setting mode is set,
Based on the boom length, the heave angles corresponding to the first and second boom radii are determined as calculated heave angles (θ ₁ , θ ₂ ), and the first and second detected heave angles (θ′ ₁ , θ′ ₂ )
and the first and second calculated undulation angles, the first zero adjustment coefficient (Δθ ₀ ) and the first gain adjustment coefficient (K〓) are calculated as Δθ ₀ =θ′ ₁ −(θ
′ ₂
−θ′ ₁ ) θ ₁ /(θ ₂ −θ ₁ ) and K=(θ ₂ −θ ₁ )/
(θ′ ₂
−θ′ ₁ ) and storing it in the second storage unit; The second boom support force is read out as the calculated boom support force (T ₁ ), and when a cargo with a known load (W ₂ ) is suspended on the boom, the known load is applied and the calculation is performed based on the detected undulation angle. The limit load and the first jib support force are read from the first storage unit, and the calculated jib support force ( _T2 ) at the known load is calculated as _T2 =(Ta- _T1 ) _W2 /Wa+ _T1. 2, the detected boom supporting force (T' ₁ ) in a state where no cargo is suspended from the boom, and the detected boom supporting force (T' ₂ ) due to the known load, and the calculated jib supporting force (T' ₁ , _T2 )
and the detected jib support force (T' ₁ , T' ₂ ), the second zero adjustment coefficient (ΔT ₀ ) and the second gain adjustment coefficient (K _T ) are respectively set as ΔT ₀ =T' ₁ - (T′ ₂
−T′ ₁ )T ₁ /(T ₂ −T ₁ ) and K _T =(T ₂ −T ₁ )/
(T' ₂ - T' ₁ ) and storing it in the second storage section; (W) When an unknown cargo is lifted, the detected undulation angle (θ') and the detected boom support force (T')
Then, the detected undulation angle (θ') is corrected by the first zero adjustment coefficient and the first gain adjustment coefficient, and the corrected undulation angle (θ) is calculated as θ=(θ'−Δθ ₀ )×K〓 The detected boom support force (T') is corrected by the second zero adjustment coefficient and the second gain adjustment coefficient to obtain the corrected jib support force (T) as T = (T' - ΔT ₀ )
×K _T , and the limit load from the first storage unit based on the corrected undulation angle;
The first and second boom support forces are read out, and the unknown load is calculated as W=(T-T ₀ ) based on the corrected boom support force, the limit load, and the first and second jib support forces. A fifth means for determining Wa/(Ta-T ₀ ) is provided, and the present invention is characterized in that an alarm is issued when the unknown load is equal to or greater than the limit load.

(Example) The present invention will be explained below with reference to Examples.

Referring to FIG. 8, the crane 1 is
The boom 3 has one end pivotally attached to the boom 3, and the other end of the boom 3 is supported by a support wire rope 4. A pulley 5' equipped with a hook is suspended from the boom 3 via a hoisting wire rope 5. A load (load W) 6 is suspended from this pulley 5'.
The load 6 can be raised or lowered by winding up or lowering the hoisting wire rope 5.
Furthermore, the boom 3 can be rotated in the horizontal direction by winding the upper winding body 2, and the boom 3 can change the undulation angle (θ) by winding and unwinding the support wire rope 4. I can do it. Therefore, when the load 6 is not suspended, a tension (moment) corresponding to the undulation angle (θ) due to the weight of the boom 3 is applied to the support wire rope 4, while when the load 6 is suspended, the boom A tension corresponding to the undulation angle θ due to the weight of the load 3 and the weight of the load 6 is applied to the support wire rope 4. and,
The boom 3 is provided with a boom angle detector 7 for measuring the undulation angle (θ) of the boom 3, while a boom angle detector 7 is provided in the middle or at the end of the support wire rope 4 for measuring the tension of the support wire rope 4. A tension detector 8 is attached. Note that a boom tension detector 8' may be installed in the middle of the hoisting rope 5 for directly measuring the tension of the hoisting wire rope 5.

Here, with reference to FIG. 1, the configuration of the crane overload detection device according to the present invention will be explained.

The boom angle detector 7 and the boom tension detector 8 are connected to a calculation device (calculation section) 9. On the other hand, this calculation section 9 includes a boom constant setting device 10, a first storage section 11, a second storage section 12, and a mode setting device 1.
3. A data input device 14 and an alarm device 15 are connected.

Here, referring also to FIGS. 2a and 2b, the setting mode is set using the mode setting device 13. No-load condition (no load suspended on the boom)
Then, reduce the luffing angle and make the boom stationary (Figure 6a). At this time, the working radius (the radius shown by R in FIG. 8) is actually measured (specifically, it is measured using a tape measure or the like). Note that this actual measurement value is _R1 . This working radius R ₁ is input from the data input section 14, and a boom constant (boom length (l), etc.) is set from the boom constant setting device 10. On the other hand, the boom angle (θ' ₁ ) is input to the calculation unit 9 by the boom angle detector. The calculation unit 9 calculates the heave angle θ ₁ from the working radius (R ₁ ) and the boom constant, and holds the calculated heave angle θ ₁ and the detected heave angle θ′ ₁ .

In the same way, increase the luffing angle and make the boom stationary (Figure 6b). Measure the working radius at this time (set it as R ₂ ). This working radius R ₂ is input from the data input section 14 . On the other hand, the boom angle detector 7
The heave angle (θ' ₂ ) of the boom is input to the calculation unit 9 by the following. The calculation unit 9 calculates the heave angle (θ ₂ ) from the working radius (R ₂ ) and the boom constant, and holds the calculated heave angle θ ₂ and the detected heave angle θ′ ₂ .

Thereafter, the calculation unit 9 uses the above-mentioned calculated undulation angles θ ₁ , θ ₂ and detected undulation angles θ′ ₁ , θ′ ₂ to obtain an angle zero correction coefficient Δθ ₀ and an angular span correction coefficient K〓. That is, the angle zero correction coefficient Δθ 0 is calculated by the following equation (2), and the angle zero correction coefficient Δθ ₀ is calculated by the equation (3).
Find the angle span correction coefficient K by the formula (Figure 4 shows before correction (solid line), after zero correction (dotted chain line),
and the relationship between the detected undulation angle and the calculated undulation angle after zero and span correction (double-dashed line).

Δθ ₀ = θ′ ₁ −θ′ ₂ −θ′ ₁ /θ ₂ −θ ₁ θ ₁ …(2) K〓=θ ₂ −θ ₁ /θ′ ₂ −θ′ ₁ …(3) And this angle The zero correction coefficient Δθ ₀ and the angular span correction coefficient K〓 are stored in the second storage unit 12.

Next, when the boom is stopped in a no-load state (Fig. 6b) and zero load is input from the data input device 14 (in other words, no cargo is suspended on the boom (no-load state)), Therefore, input zero load (load = 0) from the data input device 14),
The tension (T′ ₁ ) of the support wire rope is detected by the boom tension detector 8 and input to the calculation section 9 .
By the way, the first storage unit 11 stores in advance the limit load (W _a ) for each undulation angle (or working radius), the tension of the supporting wire rope (Ta) when the limit load is lifted, and the unloaded (when the load is suspended) tension in the supporting wire rope (T ₀ ) when
is stored (as shown in FIG. 7). Due to the above-mentioned zero load input, the calculation unit 9 detects the boom angle detector 7.
The tension _{( T 0 =}
T ₁ ).

Furthermore, when a load with a known load (W ₂ ) is lifted (FIG. 6c), the tension (T' ₂ ) of the support wire rope is detected by the boom tension detector 8 and input to the calculation section 9. On the other hand, as described above, this known load (W ₂ ) is input from the data input device 14. The calculation unit 9 reads the limit load W _a , tension T _a and T ₀ corresponding to the detected heave angle (θ' ₃ ) and the working radius (R ₃ ) obtained from the boom constant from the boom angle detector 7, and calculates the following: Using equation (4), the known load (W ₂ )
Find the tension T ₂ of the supporting wire rope by.

T ₂ = (Ta - T ₁ ) x (W ₂ /Wa) + T ₁ ... (4) (However, T ₁ = T ₀ ) After that, the calculation unit 9 calculates the above-mentioned calculated tensions T ₁ and T ₂ and detected tension T' ₁ and T′ ₂ to find the tension zero correction coefficient ΔT ₀ and the tension span correction coefficient K _T . That is,
The tension zero correction coefficient ΔT ₀ is calculated by the following equation (5).
Calculate the tension span correction coefficient K _T using equation (6) (Figure 5 shows the detected tension and calculation before correction (solid line), after zero correction (dotted chain line), and after zero/span correction (double-dotted line). (shows the relationship with tension).

ΔT ₀ =T′ ₁ −T′ ₂ −T′ ₁ /T ₂ −T ₁ T ₁ …(5) K _T =T ₂ −T ₁ /T′ ₂ −T′ ₁ …(6) And this tension The zero correction coefficient ΔT ₀ and the tension span correction coefficient K _T are stored in the second storage unit 12 .

Next, referring to FIGS. 1 and 3, after setting the zero adjustment coefficients Δθ ₀ , ΔT ₀ and the span adjustment coefficients K〓, K _T as described above, (hereinafter referred to as unknown cargo) using a crane, set the normal mode using the mode setting device 13, and set the normal mode using the boom constant setting device 10.
Set the boom length (l) etc. from the above and lift the unknown cargo. In the normal mode, the boom angle (θ') and the tension of the support wire rope (T') are continuously detected by the boom angle detector 7 and the boom tension detector 8, respectively.

The boom angle (θ') input to the calculation unit 9 is corrected as shown in equation (7) by the angle zero adjustment coefficient Δθ ₀ and the angle span adjustment coefficient K〓 read from the second storage unit 12. Ru.

θ(θ′−Δθ ₀ )×K〓 (7) (where θ is the corrected boom angle) The calculation unit 9 calculates the working radius (R) from the corrected boom angle (θ) and the boom length (l). on the other hand,
The tension (T') of the support wire rope is corrected by the tension zero adjustment coefficient ΔT ₀ and the tension span adjustment coefficient K _T read from the second storage section 12 as shown in equation (8).

T = (T'-ΔT ₀ ) × K _T … (8) (T is the corrected tension) Limit load corresponding to the working radius (R) mentioned above
W _a , tension T _a and T ₀ are read out from the first storage section 11 to the calculation section 9 . Then, the unknown cargo (W) is calculated based on the above-mentioned equation (1) using the above-mentioned corrected tension, limit load W _a , tension T _a and T ₀ .

Further, the calculated load (W) is compared with the limit load (W _a ), and if W≧W _a , the calculation unit 9 sends out an alarm signal, and the alarm 15 sounds accordingly.

(Effects of the Invention) As explained above, in the present invention, zero adjustment and span adjustment of the boom angle detector and boom tension detector can be performed without the need to adjust the variable resistor as in the conventional case. It is extremely easy to adjust the span as it does not require any skill and there is no need to lower the boom to the ground. Therefore, even when there are many types of attachments such as booms and jibs, such as a lattice boom crane, zero adjustment and span adjustment are easy, and adjustments due to individual differences among cranes are also easy.

Furthermore, since zero adjustment and span adjustment can be performed without using a variable resistor as in the past, the reliability of the zero adjustment coefficient and span adjustment coefficient is high.
The accuracy of overload detection can be increased.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overload detection device according to the present invention, FIGS. 2 a and b are diagrams showing processing in setting mode, FIG. 3 is a diagram showing processing in normal mode, and FIG. 4 5 shows the relationship between the calculated undulation angle and the detected undulation angle before correction, after zero correction, and after zero span correction. FIG. 5 shows the relationship between calculated tension and detected tension before correction, after zero correction, and after zero span correction. Figures shown after zero and span correction; Figures 6 a to c are diagrams showing the operation of the crane when determining the zero correction coefficient and span correction coefficient; Figure 7 shows the data stored in the first storage section shown in Figure 1 in advance. The memorized limit load (W _a ), the tension of the support wire rope when the limit load is suspended (T _a ), and the tension of the support wire rope when no load is applied (T ₀ ) and the working radius (boom angle) FIG. 8 is a diagram showing the crane. 1... Crane, 2... Upper girder, 3... Boom,
4... Boom support wire rope, 5... Hoisting rope, 6... Load, 7... Boom angle detector, 8... Boom tension detector, 8'... Hoisting rope tension detector, 9...
Arithmetic unit, 10...Boom constant setting device, 11...First storage section, 12...Second storage section, 13...Mode setting device, 14...Data input device, 15...Alarm device.

Claims (1)

[Claims] 1 Used in a crane that is equipped with a boom with one end pivotally attached to the revolving structure and the other end supported by a support wire rope, and used to suspend cargo, and for detecting overload of the crane. In the overload detection device, a boom angle detection unit for detecting the undulation angle of the boom as a detected undulation angle; a boom support force detection unit for detecting the support force applied to the support wire rope as the detected support force;
The limit load (Wa) of the crane depending on the undulation angle, the first boom support force (Ta) applied to the support wire rope by the limit load and the boom's own weight, and the support by the boom's own weight. A first storage unit stores the second boom support force (T ₀ ) applied to the wire rope, and a zero adjustment coefficient and a gain adjustment coefficient in the boom angle detection unit are stored as a first zero adjustment coefficient and a first zero adjustment coefficient, respectively. a second storage unit for storing the zero adjustment coefficient and the gain adjustment coefficient in the boom supporting force detection unit as a second zero adjustment coefficient and a second gain adjustment coefficient, respectively; a calculation unit for calculating the first and second zero adjustment coefficients and the first and second gain adjustment coefficients, and for calculating the actual load of the cargo lifted by the boom; A mode for switching the calculation unit between a setting mode in which calculation of the first and second zero adjustment coefficients and the first and second gain adjustment coefficients is specified, and a normal mode in which calculation of the actual load is specified. and a setting section, the calculation section is given the first and second boom radii (R 1 , R 2 ) of the boom when the setting mode is set, and is given the first and second boom radii (R ₁ , R ₂ ) of the boom based on the boom length. The undulation angles corresponding to the first and second boom radii are determined as calculated undulation angles (θ ₁ , θ ₂ ), and the first and second detected undulation angles (θ′ ₁ , θ′ ₂ ) and the first and second boom radii are calculated. Using the second calculated undulation angle, the first zero adjustment coefficient (Δθ ₀ ) and the first gain adjustment coefficient (K〓) are respectively calculated as Δθ ₀ =θ′ ₁ −(θ′ ₂ −θ′ ₁ ) θ ₁
/(θ ₂
−θ ₁ ) and K=(θ ₂ −θ ₁ )/(θ′ ₂ −θ′ ₁ ) and storing the obtained result in the second storage unit;
When no cargo is suspended on the boom, the second boom support force is read out from the first storage unit as the calculated boom support force (T ₁ ) based on the detected undulation angle, and a known load is applied to the boom. When the cargo (W ₂ ) is suspended, the above known load is applied,
The limit load and the first jib support force are read from the first storage unit based on the detected undulation angle, and the calculated jib support force (T ₂ ) at the known load is T ₂
= (Ta−T ₁ )W ₂ /Wa+T ₁ The second means is obtained, and the detected boom support force (T′ ₁ ) in a state where no cargo is suspended from the boom and the detected boom support force using the known load. (T′ ₂ ),
_The second zero adjustment coefficient (ΔT ₀ ) and _{the second} gain adjustment coefficient ₍ K _T ) and ΔT ₀ = T′ ₁ − (T′ ₂ − T′ ₁ ) T ₁ /
(T ₂ −T ₁ ) and K _T =(T ₂ −T ₁ )/(T′ ₂ −T′ ₁ ) and storing the obtained result in the second storage unit; , when the normal mode is set, when a cargo whose load (W) is unknown is hung on the boom, the calculation unit receives the detected undulation angle (θ') and the detected boom support force (T'). ,
Correcting the detected undulation angle (θ') with the first zero adjustment coefficient and the first gain adjustment coefficient to obtain a corrected undulation angle (θ) as θ = (θ' - Δθ ₀ ) × K〓, The detected boom support force (T') is corrected by the second zero adjustment coefficient and the second gain adjustment coefficient to obtain a corrected jib support force (T) as T=(T'-ΔT ₀ )×K _T The limit load, the first and second jib support forces are read out from the first storage section based on the fourth means for determining and the corrected luffing angle, and the corrected boom support force, the limit load, and the Based on the first and second jib support forces, the unknown load is W=
(T-T ₀ )Wa/(Ta-T ₀ ) and a fifth means for calculating as (T-T 0 )Wa/(Ta-T 0 ), and when the unknown load is equal to or higher than the limit load, an alarm is issued. Crane overload detection device.