JP2597984B2 - Overload prevention device for arm type crane - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an overload protection device for an arm type crane having a load suspension device such as a grapple, a lifting magnet, a log hawk, etc. The present invention relates to a device for preventing overload by comparing a rated gross weight determined from the working radius with a weight of a load suspension device and an equivalent weight applied to an arm tip of an actual load.

[Background of the Invention]

For example, in an arm type crane equipped with a lit magnet (hereinafter, referred to as a rif mag) as a load suspension device, when the rif mag absorbs a load exceeding a rated load, the rif mag causes a swing, which makes it difficult to perform work. In the worst case, there is a danger of the crane body falling over.

As a conventional technique to prevent such a crane falling accident, the vertical load applied to the tip of the crane arm and the distance from the center of rotation of the arm to the tip of the arm are determined. The technology you need exists.

However, in an arm type crane equipped with a rif mag, the rif mag does not always face vertically downward, but can rotate in an arbitrary direction depending on the operation position of the rif mag cylinder. The position cannot always be on a vertical straight line passing through the pin for mounting the rif mag on the tip of the arm, and it changes at any time depending on the operating position of the rif mag cylinder, so that it is difficult to find the limit load that causes the crane to overturn. There was a point.

Further, the above-mentioned problem also occurs in an arm type crane equipped with a grapple, a log hawk, or the like.

[Object of the invention]

An object of the present invention is to provide a crane having a load suspension device rotatably mounted at the tip of an arm via a pin and having a load suspension device. It is to provide a device.

[Summary of the Invention]

In order to achieve this object, the present invention provides a boom mounted on a crane body so as to be able to be raised and lowered, an arm rotatably attached to a tip of the boom, and a pivotable pin at a tip of the arm via a pin. An arm type crane comprising a load suspension device to be mounted, a boom cylinder for raising and lowering a boom, an arm cylinder for rotating an arm, and a load suspension device cylinder for rotating the load suspension device, wherein a tilt of the crane body is Body tilt angle detector that detects the angle,
A boom angle detector for detecting the boom undulation angle, an arm angle detector for detecting a relative angle between the boom and the arm, a load suspension angle detector for detecting a relative angle between the arm and the load suspension device, and the pin at the tip of the arm is received. A load detector for detecting a vertical force and a horizontal force, respectively, a pressure detector for detecting a pressure on a bottom side and a rod side of a load suspension device cylinder, respectively, and a distance between the arm, the boom, and a support point of the load suspension device. And a storage unit for storing the weight of the load suspension device, a signal of each of the detectors and data of the distance stored in the storage unit, and a captured signal of the body angle detector and a boom angle detector. The working radius of the crane is calculated using the signal of the arm angle detector, the signal of the load suspension device angle detector, and the distance data, and The weight of the load suspension device is obtained by using the signal of the slant angle detector, the signal of the boom angle detector, the signal of the arm angle detector, the signal of the load suspension angle detector, the signal of the load detector, and the signal of the pressure detector. And the actual load, calculate the equivalent weight applied to the pin at the tip of the arm, compare the total rated load determined from the calculated working radius with the sum of the equivalent weights, and calculate the total rated load of the sum of the equivalent weights. And an operation unit for outputting an overload signal when the ratio to the predetermined value exceeds a predetermined value.

(Example of the invention)

An embodiment of the present invention will be described below with reference to FIGS. This embodiment describes an arm type crane equipped with a rif mag as a load suspension device. First
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, 3 denotes an arm rotatably attached to a tip end of the boom 2, and 4 denotes an arm 3
A boom cylinder for raising and lowering the boom 2, a boom cylinder 6 for raising and lowering the boom 2, an arm cylinder 7 for rotating the arm 3, and a pivot 8 about the riff mag 4 about the pin 5 as a fulcrum. The rod 8a is connected to the rif mag 4 via links 9 and 12. Reference numeral 10 denotes a pin for connecting the rod 8a and the links 9 and 12, reference numeral 11 denotes a pin for connecting the link 9 to the riff mag 4, and reference numeral 13 denotes a pin for connecting the link 12 to the arm 3. Reference numeral 23 denotes a scrap adsorbed by the riff mag 4.

As shown in FIGS. 1 and 2, an overload prevention device according to the present invention is provided on a crane main body 1 and detects a tilt angle (ground angle) of the crane main body 1; Boom angle detector 15 provided at the base of the boom 2 to detect the boom 2; an arm angle detector 16 provided at the tip of the arm 2 to detect the relative angle between the boom 2 and the arm 3; A riff mag angle detector 17 provided at the portion of the pin 5 for detecting the relative angle of 4;
Detects a horizontal force (Fx in FIG. 4 and a force perpendicular to the direction of gravity) applied to the pin 5 and a vertical force (Fy in FIG. 4 and a force in the direction of gravity). Load detector 18
And a pressure detector 19 provided on the rif mag cylinder 8 for detecting the bottom pressure and the rod side pressure of the rif mag cylinder 8. The above-described load detector 18 can be realized by, for example, a force detecting means described in Japanese Patent Application Laid-Open No. 59-207395. Further, as shown in FIG. 3, there is provided an arithmetic unit 20 which takes in signals from the detectors 14 to 19, performs calculations and comparisons described later, and outputs an overload signal.

The arithmetic unit 20 takes in the signals from the detectors 14 to 19, calculates the working radius of the crane (eA in FIG. 1), obtains the rated total load determined from the working radius, and Based on the signal from ~ 19, find the equivalent weight applied to the arm tip of the arm of the rif mag and the actual load, compare the equivalent weight with the rated total load, and determine that the equivalent weight has approached the rated total load, or exceeded Output an overload signal when it is determined that

The arithmetic unit 20 is configured to execute the arithmetic processing,
It has a storage unit 20a, a calculation unit 20b, and an input / output unit 20c. The storage unit 20a includes a distance between the base of the boom 2 and the tip, a distance between the pivot point of the arm 3 and the tip,
The distance between the pin 5 and the pin 11, the distance between the pin 5 and the center of gravity of the rif mag 4, the weight W0 of the rif mag 4, and the like are stored. Further, the arithmetic unit 20 is connected to a display unit 21 for displaying a working radius, a rated gross weight, an actual load, and the like of the crane, and an alarm unit 22 for issuing an alarm based on an overload signal.

 Next, the operation of the above-described embodiment will be described.

The arithmetic unit 20b of the arithmetic unit 20 includes the main body tilt angle detector 14, the boom angle detector 15, and the arm angle detector shown in FIG.
16. By inputting each detection signal from the riff mag angle detector 17 and the distance data in the storage unit 20a, a working radius eA from the turning center of the crane main body 1 to the pin 5 at the tip of the arm 3 is calculated. The rated total weight according to the calculated working radius eA is obtained. This calculation method is described in detail in the proposal by the present applicant in Japanese Patent Application No. 59-178299 (Japanese Patent Application Laid-Open No. 61-60598), and the description thereof is omitted here.

Next, the calculation unit 20b calculates the actual amount of the scrap 23 adsorbed by the rif mag 4 based on the detection signals from the load detector 18, the pressure detector 19, and the angle detectors 14 to 17 based on the following expression (3). The load (W) is calculated, and the calculated actual load (W) of the scrap 23 shown in FIG. 4 and the previously stored weight (W0) of the rif mag 4 are at the position of the pin 5 at the tip of the arm 3. Weight (Wo '+ Wo) from the viewpoint of the turning moment of the crane body 1 in the case (5) will be described later.
It is calculated based on equation (6). Then, the equivalent weight is compared with the total rated load, and when it is determined that the equivalent weight approaches the total rated load, an overload signal is transmitted to the display device 21 and the alarm device 22.

The principle of the arithmetic processing in the arithmetic device 20 will be described in detail below.

 In FIG. 4, the expansion / contraction force A of the rif mag cylinder 8 is represented by A = | PR · SR−PB · SB |.

Here, PR and PB are the rod side pressure and the bottom side pressure of the rif mag cylinder 8, and SR and SB are the rod side area and the bottom side area of the rif mag cylinder 8.

The X-direction component Fx and the Y-direction component Fy of the force F applied to the pin 5 (detected by the load detector 18) are represented by the following equations, respectively.

Fx = F cos γ, Fy = F sin γ The X-direction component Bx and the Y-direction component By of the expansion / contraction force A of the rif mag cylinder 8 with respect to the link 9-axis direction component B are expressed by the following equations, respectively.

Bx = B cos β, By = B sin β In FIGS. 4 and 5, the distance in the X-axis from the center of the load detector 18 to the center of gravity of the scrap 23 is e, and the distance between the center of the load detector 18 and the Is the distance in the X-axis direction to the center of gravity of e0, the distance (working radius) in the X-axis direction from the center of the load detector 18 to the turning center of the crane body 1 is eA, and the load detector 18 is
The distance in the X-axis direction from the center of the pin 11 to the center of the pin 11 is eB, and the distance in the Y-axis direction from the center of the load detector 18 to the center of the pin 11 is
eC, the actual load of the scrap 23 is W, the weight of the riff mag 4 is Wo
Then, the following equation is established by the moment around the load detector 18 and the balance in the Y-axis direction.

Wo · e0 + W · e−By · eB−Bx · eC = 0 (1) Wo + W + Fy−By = 0 (2) From the equations (1) and (2), W and e are obtained as follows.

W = By−Fy−Wo (3) e = (By · eB + Bx · eC−Wo · e0) / (By−Wo−Fy)
(4) Here, Wo is known because it is set in advance, and Fy
Is the load detector 18, By is the detection signal from the pressure detector 19 and the riff mag angle detector 17, and eo, eB, eC are the main body tilt angle detector 14, the boom angle detector 15, and the arm angle detector 1.
6. It can be detected by the riff mag angle detector 17 and the distance value stored in advance.

On the other hand, the riff mag 4 and the scrap
The equivalent weight of the turning moment around the center of rotation of the crane body 1 with the 23 actual loads W is (Wo '+ W). When Wo 'and W are obtained in consideration of the moment around the turning center of the crane main body 1, the following equations are obtained.

Therefore, from the equations (5) and (6), the equivalent weight (Wo '+
W ′) is determined, and the total rated load according to the working radius eA is also determined as described above, so that the two can be compared. As a result, when it is determined that the equivalent weight approaches the rated total load, or when it is determined that the equivalent weight has exceeded, the overload signal is output from the arithmetic unit 20, an alarm is issued from the alarm unit 22, and the display unit 21 displays. Is displayed.

As described above, according to the present embodiment, since the overload on the lift mag 4 can be prevented, the load swing of the lift mag 4 or the accident of the crane body falling over can be prevented.

Although the above-described embodiment has been described with respect to the example in which the rif mag 4 is used as the load suspension device, the present invention is also applicable to an arm type crane using a grapple, a log hawk, or the like. FIG. 6 shows an example in which a grapple 24 is used as an example. A grapple angle detector 17 'is attached to a pin 5' for rotatably connecting the tip of the arm 3 and the grapple 24. And a load detector 18 '. In this embodiment, the operation as the overload prevention device is the same as that of the above embodiment, and the description thereof will be omitted.

〔The invention's effect〕

As described above, according to the present invention, it is possible to promptly detect an overload of a suspension load in accordance with the rotation posture of a load suspension device rotatably mounted via a pin at the tip of an arm. As a result, it is possible to prevent the swinging of the load suspension device or the overturn of the crane main body beforehand, so that the safety thereof can be improved and the efficiency of the cargo handling work handled by the load suspension device can be improved.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is an overall side view of an arm type crane provided with an overload prevention device according to the present invention, and FIG. FIG. 3 is a block diagram of the control unit, FIG. 4 is a force line diagram of the force in the rif mag unit, FIG. 5 is a diagram showing only the force lines, and FIG. 6 is another embodiment of the present invention. It is a partial view when a grapple is attached as an example. 1 ... Crane body, 2 ... Boom, 3 ... Arm, 4
... Rif mag, 5 ... Pin, 6 ... Boom cylinder, 7
…… Arm cylinder, 8… Rif mag cylinder, 14 ……
Body tilt angle detector, 15… Boom angle detector, 16 ……
Arm angle detector, 17… Rif mag angle detector, 18 ……
Load detector, 19 ... Pressure detector, 20 ... Computing device, 21 ...
... display device, 22 ... alarm device.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Takeshi Aritake 650, Kandamachi, Tsuchiura-shi Hitachi Construction Machinery Co., Ltd. Inside the Tsuchiura Plant (56) References JP-A-51-108454 (JP, A) JP-A-56-28193 (JP, A) JP-A-59-92894 (JP, A)

Claims (3)

(57) [Claims] 1. A boom mounted on a crane body so as to be able to move up and down, an arm rotatably mounted on a tip of the boom, and a weight suspension device rotatably mounted on a tip of the arm via a pin. And a boom cylinder for raising and lowering the boom, an arm cylinder for rotating the arm, and a weight suspension device cylinder for rotating the weight suspension device. Angle detector, boom angle detector to detect boom undulation angle, arm angle detector to detect relative angle between boom and arm, load suspension angle detector to detect relative angle between arm and load suspension device, arm tip A load detector for detecting the vertical and horizontal forces received by the pin, and the pressure on the bottom and rod sides of the load suspension cylinder. A pressure detector for detecting each is provided, the arm, the boom, a storage unit for storing the distance between the support points of the load suspension device and the weight of the load suspension device, and a signal of each of the detectors and stored in the storage unit. The data of the distance is taken, and the signal of the taken main body angle detector, the signal of the boom angle detector, the signal of the arm angle detector, the signal of the load suspension device angle detector, and the crane using the distance data are taken. Calculate the working radius of the main body tilt angle detector, boom angle detector signal, arm angle detector signal, load suspension device angle detector signal, load detector signal and pressure Using the signal of the detector, the equivalent weight applied to the pin at the arm tip of the load suspension device weight and the actual load, respectively, is calculated, and the sum of the rated total load and the equivalent weight determined from the calculated working radius is calculated. ratio And an arithmetic unit having an arithmetic unit for outputting an overload signal when the ratio of the sum of the equivalent weights to the rated total load exceeds a predetermined value. Overload protection device. 2. The arithmetic unit has a working radius of a crane,
2. The overload protection device for an arm type crane according to claim 1, further comprising a display device for displaying a rated gross weight, an actual load, and the like. 3. The overload prevention device for an arm type crane according to claim 1, wherein said arithmetic unit is provided with an alarm device for issuing an alarm by said overload signal.