JPH0714795B2 - Crane overload prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is intended to secure stability against falling and breakage during operation of a jib crane or the like having a main hoisting device and an auxiliary hoisting device. Crane overload prevention device.

(Prior Art) Generally, in this type of crane overload prevention device, both output signals of a load sensor for detecting a hanging load and an angle sensor for detecting a tilt angle of a jib are stored in advance in a computing unit. Comparing with the rated load for the working radius, before the crane body loses stability due to excessive lifting load, the jib is broken, or the wire rope of the hoisting device is cut, the driver and the ground worker Is to issue a warning.

By the way, in the conventional crane overload prevention device,
When processing the output signal of each sensor, processing by a precision mechanical device of the method of driving the cam by Celsin to read the rotation amount, or analog calculation processing by a transistor circuit, digital calculation comparing with the rated load value calculated in advance Processing is becoming the mainstream.

(Problems to be Solved by the Invention) However, according to the configuration of the above-described related art, (a) the case of suspending a suspension load by both the main hoisting device and the auxiliary hoisting device is not considered. (B) When it is used in a jib crane, etc., mechanical vibration, mechanical fine gears, oil depletion, etc. reduce the durability of the mechanical device, and (c) the overload prevention device's overall responsiveness and accuracy are low. (D) Since the rated load value for the working radius calculated for each crane must be stored in advance, software costs are high, and there is a problem that the error of the actually mounted crane cannot be corrected.

The present invention has been made for the purpose of solving such a problem, and in consideration of the case of co-suspension, the output signal of each sensor is instantly processed by a microcomputer having an IC chip, and thereafter, all are processed. The information is processed immediately.

(Means for Solving Problems) The crane overload prevention device of the present invention has a main hoisting device and an auxiliary hoisting device as means for solving the above-mentioned problems, and any one of the suspension loads is used. In an overload prevention device such as a jib crane that can be hung independently by one hoisting device or can be hung together by both hoisting devices, two load sensors that detect the hoisting load of each hoisting device and the tilt angle of the jib It is equipped with an angle sensor for detecting and an arithmetic unit for arithmetically processing the output signals of these sensors. The arithmetic unit has an A / D board and a CPU board, and the A / D board has an output signal of each sensor. Each has a circuit that converts the digital value of weight and angle, CP
The U board calculates a working radius of the jib from the digital value and a rated load for independent suspension or co-suspension in the working radius, and compares the rated load and the value of the suspension load with a circuit for momentary comparison and calculation. The present invention is characterized in that the result of the comparison calculation is displayed moment by moment and an alarm signal or the like is issued when a constant value is reached.

(Operation) In the above configuration, while the jib crane or the like is working, each load sensor and angle sensor detect the hanging load and the tilt angle of the jib when individually or co-suspended, and the A / D signal is output.
Type on the board. The A / D board converts each signal into a digital value of instantaneous weight and angle and inputs it to the CPU board. C
The PU board immediately calculates the working radius of the jib and the rated load for independent suspension or co-suspension in the working radius from the data, and compares and calculates the rated load and the value of the suspension load. The rated load changes as the working radius of the jib changes. Therefore, the calculation is performed every moment, and the result of the comparison calculation is also displayed every moment, and when a certain value is reached, an alarm signal or a voice signal is issued.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS.

In this embodiment, as shown in FIG. 4, a tower type jib crane 1
When used for. The tower-type jib crane 1 has a gate structure 3 mounted on a rail 2 laid on the ground so that the gate structure 3 can travel freely.
The lower end of the center frame 5 is rotatably supported by the foot bearing 4 provided at the center of the gate structure 3, and the base of the jib 6 is movably supported at the middle of the center frame 5 and at the upper end thereof. An intermediate portion of the swing lever 7 is swingably supported, and a driver's cab 8 and a machine compartment 9 are provided in front of and behind the intermediate portion of the center frame 5, respectively. A main hoisting device 10 and an auxiliary hoisting device 11 are arranged in the machine room 9. One end of two wire ropes 13 is connected to the hoisting drum 12 of the main hoisting device 10, and the other end is wound around a hook block sheave 16 via a swing lever rear end sheave 14 and a jib tip sheave 15. The main hook block 17 is hung, the original path is folded back, and the main hook block 17 is connected to the main winding load sensor 18 provided in the machine room 9. Further, one end of the two wire ropes 20 is connected to the hoisting drum 19 of the auxiliary hoisting device 11, and the other end is connected to the upper sheave 2 of the center frame.
1, jib intermediate sheave 22 via hook sheave 2 sheave
The auxiliary winding hook block 24 is hung around 3, the original path is folded back, and it is connected to the auxiliary load sensor 25 provided in the machine room 9.

As shown in FIG. 3, the main winding load sensor 18 has a pin between the mounting portion 26 and the clevis portion 27 fixed to the floor surface of the machine room 9.
The link part 29 is provided via the 28, the strain gauge 30 is attached to the middle part of the link part 29, and the clevis part 27
The other end of each wire rope 13 is connected to both ends of the.
The strain gauge 30 is configured in a bridge circuit, and the suspension load 31 in the main hook block 17 causes the wire rope 13,
When the tension acts on the link part 29 via the clevis part 27, an output corresponding to the suspension load 31 is emitted as a signal. The auxiliary winding load sensor 25 is also configured similarly to the main winding load sensor 18 (not shown), and outputs an output corresponding to the suspension load 32 in the auxiliary winding hook block 24 as a signal. Further, when a single suspension load 33 is hung together by both hook blocks 17 and 24, both load sensors 18 and 25 emit an output corresponding to the suspension load shared by each hook block 17 and 24 as a signal.

An angle sensor 34 is provided below the jib 6. The angle sensor 34 has a pendulum type potentiometer incorporated in the housing (not shown), and the horizontal line H- of the jib 6 is
The inclination angle θ with respect to H is output as a signal.

A calculator 35 is provided in the cab 8. Calculator 35
Is a power board 37, an I / O board 38, an A / D board 39, and a CP in a housing 36 as shown in FIGS.
U board 40 is inserted, CPU board 40 consists of ROM 41, RAM 42, arithmetic IC block 43 and discrimination block 44, and switching switch 45, forecast lamp 46, alarm buzzer 47, automatic stop signal output device 48 on the front of housing 36, A level meter 49 and an indoor display 50 are provided, and a plurality of selection switches 51 are provided on the side surface of the housing 36.

A plurality of outdoor indicators 52 are arranged outside the cab 8.

The crane overload prevention device 53 of this embodiment includes the main winding load sensor 18, the auxiliary winding load sensor 25, the angle sensor 34, and the computing unit.
35 and the outdoor display 52, the operation of which will be described below.

The driver uses the switching switch 45 to individually suspend the program by the main hoisting device 10, the single hoisting device by the auxiliary hoisting device 11 or the co-suspending device by the main and auxiliary hoisting devices 10 and 11 in the arithmetic IC block 42, respectively. It is configured and is designed to select that program.

First, in the case where the independent hoisting by the main hoisting device 10 is selected, the main hoisting device 10 is operated to hoist the hoisting load 31 of weight W (t) by the main hook block 17, and the main hoisting load sensor 18 is tensioned. The main winding load sensor 18 inputs a signal corresponding to the weight W (t) to the A / D board 39. On the other hand, the jib 6 has an actual working radius R (m) when the tilt angle is θ, and the angle sensor 34 inputs a signal corresponding to the tilt angle θ to the A / D board 39. The A / D board 39 converts both input signals into digital values of weight and angle, and inputs them to the CPU board 40. The CPU board 40 calculates the input digital value I
Data is scaled by C block 43 and stored in RAM 42. At the same time, the calculation IC block 43 uses the above data values to determine the working radius R (m) and the rated load P at the working radius R (m).
(T) is calculated and displayed on the indoor display 50 and the outdoor display 52 and stored in the RAM 42. The rated load P (t) is calculated based on the following equation (1) (5th
(See figure) Where P = rated load at working radius R (t) P ₁ = maximum rated load (t) P ₂ = rated load at maximum radius (t) R = actual working radius (m) R ₁ = at maximum rated load Working radius (m) R ₂ = maximum radius (m) Formula (1), P ₁ , P ₂ , R ₁ , R ₂ and the correction coefficient described later are stored in the ROM 41 in advance, and the calculation IC block 43
Reads these and calculates P. Since the mechanical efficiency of the mechanical system varies depending on the hoisting / lowering operation of the main and auxiliary hoisting devices 10, 11, and the hoisting operation of the jib 6, these values are stored in the ROM 41 as a correction coefficient and each load is stored. The increase / decrease or slight change in the detection amount of the sensors 18, 25 and the angle sensor 34 is grasped in the CPU board 40 to determine the winding, winding, undulation state, each direction, and the correction coefficient corresponding to this is selected. Then, it is read out from the ROM 41 and utilized in the calculation of the rated load P to make the calculation accurate. In addition to the tower type jib crane, there are various types of jib cranes, and the mechanical efficiency varies depending on the model. Therefore, the correction coefficient according to the model is stored in the ROM 41, and the selection switch 51 can select the correction coefficient according to the model.

The arithmetic IC block 43 compares P calculated by the calculation with W stored in the RAM 42, and discriminates the result.
To enter. When W reaches 95% of P, the discrimination block 44 sounds an alarm buzzer 47 or flashes the forecast lamp 46, and at the same time issues a voice forecast, and further W
When becomes equal to P, the alarm buzzer 47 is sounded and at the same time, the stop signal for dangerous operation is transmitted from the automatic stop signal output device 48.

The change information of the moment load factor Rn during this time is displayed on the level meter 49 and the indoor display 50 every moment.
The level meter 49 displays the ratio of W and P at the working radius R as a bar graph in%.

Next, even when the independent hoisting by the auxiliary hoisting device 11 is selected, the above formula (1) can be applied mutatis mutandis, and the operation of the overload prevention device 53 is the same as in the case of the single hoisting by the main hoisting device 10. It is the same. However, the actual working radius r of the jib in this case
(M) and the weight W (t) of the suspension load 32 are the actual work R when the main hoisting device 10 is used and the weight W of the suspension load 31.
It is generally smaller. Therefore, the overload preventing device 53 is more effective in ensuring the safety of the wire rope 20 and the auxiliary hoisting device 11 than the stability of the crane 1.

Finally, when the co-suspension by the main and auxiliary hoisting devices 10 and 11 is selected, a part W ′ of the weight Wm (t) of the suspension load 33 is W ′.
The main hoisting device 10 takes charge of (t), and the auxiliary hoisting device 11 of the remaining ω '(t) takes part. The load sensors 18 and 25 input signals corresponding to the weights W ′ and ω ′, and the angle sensor 34 inputs a signal corresponding to the inclination angle θ of the jib 6 to the A / D board 39, respectively. The A / D board 39 converts each input signal into a digital value of weight and angle, and inputs the digital value to the CPU board 40. The CPU board 40 uses the arithmetic IC block 43 to calculate the virtual work radius Rm (m) at this time by the following equation.

Specifically, the virtual work radius Rm is the distance between the center of gravity G of the suspension load 33 and the turning center line of the center frame 5, and corresponds to the actual work radius R or r in the case of the above independent suspension. Therefore, after that, the actual working radius Rm (m) and the weight of the suspended load Wm
As in the case of the independent suspension of (t), the above formula (1) is applied mutatis mutandis to the arithmetic processing.

As described above, whether the work is in the safe range or in the dangerous range is reliably transmitted to the driver and the ground crew by the graphic display, voice and buzzer alarm, lamp display, etc. The hanging loads 31, 32 and 33 prevent the crane 1 from losing stability, the jib 6 from breaking, and the wire ropes 13 and 20 from breaking.

Further, the signal processing from each sensor 18, 25, 34 is a digital conversion processing by the A / D board 39 having an IC chip, and all the subsequent arithmetic processing is also an immediate arithmetic processing by the CPU board 40, The durability, responsiveness and accuracy of the overload prevention device 53 are significantly improved. The display becomes more effective by changing the volume and sound quality of the alarm buzzer 47, changing the sound content, blinking the display lamps 46, 50, 52, or changing the color.

(Effect of the invention) Since the present invention is configured as described above, it is possible to secure stability against a fall of a jib crane or safety against breakage even when co-suspended by a main hoisting device and an auxiliary hoisting device. to enable. Therefore, the signal processing from the load sensor and the angle sensor does not depend on the analog arithmetic processing by the mechanical device or the transistor circuit, but is the immediate arithmetic processing by the microcomputer having the IC chip, so the durability of the crane overload prevention device, The responsiveness and accuracy are remarkably improved, and precise machinery is not required, which is economical, and unlike the conventional method of comparing with the rated load value in the allowable range calculated and stored in advance, the work radius Since it is a method of instantly calculating the rated load from the calculation formula, there is no need to change the software, and it is possible to reduce the cost during manufacturing.

[Brief description of drawings]

FIG. 1 is a system diagram of a crane overload prevention device showing an embodiment of the present invention, FIG. 2 is a perspective view of a computing unit of the present invention, FIG. 3 is a front view of a load sensor of the present invention, and FIG. Is a front view of a tower type jib crane in which the present invention is used, and FIG. 5 is a diagram showing a working radius and a relationship between the working radius and a rated load. 1 ... Tower type jib crane, 6 ... Jib, 10 ... Main hoisting device, 11
... auxiliary winding device, 18 ... main winding load sensor, 25 ... auxiliary winding load sensor, 31, 32, 33 ... hanging load, 34 ... angle sensor, 35 ... arithmetic unit,
39 ... A / D board, 40 ... CPU board, 51 ... Selection switch, 53
… Crane overload prevention device, θ… Inclination angle, P… Rated load, R, r… Working radius

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-112584 (JP, A) real-open Sho-49-74666 (JP, U) real-open Sho-61-113791 (JP, U) real open Sho-59- 2777 (JP, U)

Claims (2)

[Claims] 1. An overload preventer for a jib crane or the like, which has a main hoisting device and a supplementary hoisting device, and a hoisting load can be independently hung by either one of the hoisting devices, or can be hung together by both hoisting devices. In the device, two load sensors that detect the suspension load of each hoisting device, an angle sensor that detects the tilt angle of the jib,
Comprising a computing unit for computing the output signals of these sensors, the computing unit has an A / D board and a CPU board,
The A / D board has a circuit that converts the output signal of each sensor into digital values of weight and angle, and the CPU board is
It has a circuit that calculates the working radius of the jib from the digital value and the rated load of each hanging or co-suspended within the working radius, and compares the rated load and the value of the hanging load moment by moment. , The result of the comparison calculation is displayed momentarily,
A crane overload prevention device that emits an alarm signal when it reaches a certain value. 2. A selection switch is attached to the arithmetic unit, and a correction coefficient according to the model such as a jib crane is selectively introduced into the calculation of the suspension load by the CPU board. Crane overload prevention device.