JPH0367954B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the hanging load of a crane.

FIG. 1 is a diagram showing a crane having a conventional hanging load detection device. In the figure, 1 is the lower running body;
Reference numeral 2 denotes an upper revolving body rotatably attached to the lower traveling body 1; 3 a jib attached to the upper revolving body 2 so as to be able to raise and lower it by a foot pin 4; 5 a lifting rope;
6 is an elevation drum, 7 is a top sheave located at the tip of the jib 3, 8 is an axle of the top sheave 7,
9 is a guide sheave, 10 is a top sheave 7, a winding rope hung on the guide sheave 9, 11 is a winding drum, 12 is a hook suspended by the winding rope 10, 13 is a load suspended from the hook 12, 14
is a three-point roller type hanging load detection device.

FIG. 2 is a diagram schematically showing the hanging load detection device 14. In the figure, 15 to 17 are sheaves, 18 is a load cell that detects the force acting on the sheave 16, and the winding rope 10 is hung on the sheaves 15 to 17.

In this hanging load detection device 14, when a hanging load is applied due to crane operation, the winding rope 1
A tension T is generated at 0, and a force is applied that pushes the sheave 16 upward in the second drawing. This force is detected by the load cell 18, the tension T is calculated from the detected value, and the hanging load is determined by multiplying the tension by the number of ropes. However, in order to improve detection accuracy,
It is necessary to make the angle θ between the center line of the sheave 16 and the take-up rope 10 as small as possible;
If it is too small, the take-up rope 10 will be bent three times in an emergency, resulting in serious damage to the take-up rope 10. In addition, the winding rope 10 and the sheave 15
.about.17, the hanging load (tension T) cannot be detected accurately. Furthermore, since the hanging load detection device 14 is disposed on the back of the jib 3, it not only spoils the appearance, but also has the possibility of being damaged by falling objects when working at a construction site.

FIG. 3 is a diagram showing a crane having another conventional hanging load detection device. In the figure, 19 is a load cell that detects the tension of the elevation rope 5, and 20 is an inclinometer that detects the inclination angle of the jib 3.

In this hanging load detection device, foot pin 4
The hanging load is calculated from the balance of the surrounding moments. That is, find the first length from the inclination angle of the jib 3 to the line of action (vertical line) of the hanging load from the foot pin 4, and find the second length from the foot pin 4 to the line of action of the tension on the elevation rope 5. Next, the moment around the foot pin 4 of the jib 3 is subtracted from the product of the tension of the elevating rope 5 and the second length, and the value is divided by the first length to obtain the hanging load. However, since the point of application of the line of action of the tension of the elevating rope 5 is at the tip of the jib 3, and the elevating rope 5 forms a curve called a catenary line, it is necessary to find the tangent a at the tip of the curve. , the second length cannot be determined accurately, but it is difficult to actually measure or calculate it, so in reality, the second length is assumed to be a straight line as shown by the two-dot chain line. I am looking for the length of 2. Therefore, the accuracy of detecting the hanging load is low. Further, in order to determine the first length and the moment around the foot pin 4 of the jib 3, it is necessary to provide an inclinometer 20. Furthermore, since the above moment of the jib 3 varies depending on the inclination angle of the jib 3, not only the crane's original rated load but also
Considering the maximum value of the above moment of jib 3,
Since it is necessary to determine the capacity of the load cell 19,
The capacity of the load cell 19 must be increased, and as a result, the error in detecting the tension of the elevating rope 5 becomes large. Furthermore, since the hanging load is not directly detected but is determined from the balance of moments around the foot pin 4, complicated calculations are required, resulting in low detection accuracy.

This invention was made to solve the above-mentioned problems, and it is possible to accurately detect the hanging load, prevent damage to the winding rope, do not damage the appearance of the crane, and use an inclinometer. An object of the present invention is to provide a crane hanging load detection device that does not require the installation of a crane and can determine the hanging load by simple calculation.

In order to achieve this object, the present invention provides a device for detecting the hanging load W of a crane, which has a jib that can be lifted up and down about a foot pin, and a top sheave disposed at the tip of the jib. A force detecting means is provided which is non-rotatably attached to the jib and detects the force acting on the axle by disassembling it in the directions of first and second axes fixed to the jib at right angles; , the detected values in the second axial direction are F _x , F _y , the number of ropes on the top sheave is N, the number of take-up ropes is m, the direction of the tension of the take-up rope pulled in the direction of the take-up drum and the above The angle formed with the first axis direction, that is, the wrapping angle is α, A=F _x cosα−F _y sinα, B=
When F _x ² + F _y ² , the following formula A calculation means is provided for calculating the above-mentioned hanging load W from .

FIG. 4 is a diagram showing a part of a crane having a hanging load detection device according to the present invention, and FIG. 5 is a diagram showing A of FIG.
-A sectional view, and FIG. 6 is a BB sectional view of FIG. In the figure, 21a is a protruding piece fixed to the end of the axle 8, 21b is a knock pin that fixes the protruding piece 21a to the jib 3, and the axle 8 becomes unable to rotate relative to the jib 3 due to the protruding piece 21a and the knock pin 21b. ing. 22, 23 are grooves provided between the part of the axle 8 supported by the jib 3 and the part to which the top sheave 7 is attached; 24 _ax , 2;
4 _ay , 25 _ax , 25 _ay are active strain gauges attached to the bottom of the groove 23, 24 _dx , 24 _dy , 25 _dx ,
25 _dy is a dummy strain gauge for temperature compensation attached to the side of the groove 23, and strain gauges 24 _ax , 24 _dx ,
25 _ax and 25 _dx are provided on the axis connecting the axis of the axle 8 and the axis of the foot pin 4, that is, the x axis, and the strain gauges 24 _ay , 24 _dy , 25 _ay , 25 _dy
is provided on the axis perpendicular to the x-axis, that is, the y-axis. And active strain gauges 24 _ax , 24 _a
y , 25 _ax , and 25 _ay are attached in a direction to detect distortion of the axle 8 in a direction perpendicular to the plane of FIG. 6.
Note that a strain gauge is similarly attached to the groove 22. 26 is a hole provided in the center of the axle 8;
27 and 28 are holes that open in the grooves 22 and 23 and communicate with the hole 26; 29 is a strain gauge cord;
9 is drawn out of the axle 8 through holes 26-28. And strain gauge 24 _ax ~ 25 _d
x and strain gauges 24 _ay to 25 _dy are connected as shown in FIG. 7, respectively. Note that the strain gauges attached to the grooves 22 are also wired in the same way.

In this hanging load detection device, as shown in FIG. 8, when a force F _xp in the x-axis direction is applied to the axle 8, the strain _gauge 24
5 _ax contracts, and strain gauges 24 _dx and 25 _dx do not deform. At this time, the strain sensitivity (constant) of the strain gauge is K, the longitudinal elastic modulus of the axle 8 is E, and the groove 22
The moment of inertia of the section is I, the diameter of the groove 22 is d, the reaction force from the jib 3 against the axle 8 is R ₁ ,
The length between the points of action of R ₂ is l ₁ , the point of action of reaction force R ₂ and the force
If the length between the point of application of F _xp is l ₂ and the length between the point of application of the reaction forces R ₁ and R ₂ and the center of the grooves 23, 23 is l ₃ , then the strain gauge 24 _ax ~ 25 The output e _px1 of the bridge composed of _dx is expressed by the following equation.

e _px1 = Kdl ₂ l ₃ /EIl ₁ F _xp e _i (1) Also, the output of the bridge in the x-axis direction of the groove 22
e _px2 is expressed by the following formula.

e _px2 = Kd (l ₁ − l ₂ ) l ₃ /EIl ₁ F _xp e _i (2) Then, the sum e _px of the output e _px1 and the output e _px2 is as shown in the following equation.

e _px = Kdl ₃ /EIF _xp e _i (3) In this way, regardless of the location of the point of action of the force F _px , the sum e _px has a value that corresponds to the force F _xp . On the other hand, y
Since the strain gauges 24 _ay and 25 _ay in the axial direction do not deform, no output is generated from the bridge composed of the strain gauges 24 _ay to 25 _dy . Further, no bridge output is generated in the y-axis direction of the groove 22. Therefore,
The sum of the outputs of the two bridges in the y-axis direction e _py
is zero. Then, a force in the x-axis direction is applied to axle 8.
When F _yp acts, the sum e _py has a value according to the force F _yp , and the sum e _px is zero. Furthermore, in the x-axis direction,
When the force F acts in the middle direction in the y-axis direction, the sums e _px and e _py are the x-axis component F _x of the force F, respectively.
The value corresponds to the y-axis direction component F _y . Therefore,
The components F _x and F _y of the force F can be determined separately from the sums e _px and e _py .

FIG. 9 is an explanatory diagram of the force acting on the axle 8. As shown in the figure, when the tension of the take-up rope 10 is T and the number of ropes on the sheave on the hook 12 side is N, the hanging load W including the hook 12 is expressed by the following equation.

W=TN (4) On the other hand, the tension T acting on the top sheave 7 is the tension T of the take-up rope 10a pulled in the direction of the take-up drum 11 via the guide sheave 9, and the tension T of the sheave on the top sheave 7 and hook 12 side. There is a tension T of the winding rope 10b hung on the winding rope 10b, and the tension T of the winding rope 10a makes a constant angle (wrapping angle) α with the x-axis direction, and the number of winding ropes 10b is m. Then, the force acting on the top sheave 7 due to the tension T of the entire winding rope 10b is mT.
Note that m=N when the number N of rope hooks is an odd number, and m=N-1 when the number N of rope hooks is an even number. The line of action of the force mT is the vertical line V passing through the center of the axle 8, the top sheave 7, and the hook 12.
The line of action of the force F acting on the axle 8 (top sheave 7) due to the tension T of the take-up ropes 10a and 10b is located midway between the common tangent of the side sheave on the right side of the paper, and in an equilibrium state, the line of action of the force F acts on the axle 8 (top sheave 7) as shown in the figure. Pass through the center of 8. Also, if the angle between the x-axis and the line of action of force mT is β, then the x- and y-axis components of force F are
F _x and F _y are each expressed as follows.

F _x =Tcosα+mTcosβ (5) F _y =−Tsinα+mTsinβ (6) The tension T is calculated from equations (5) and (6) as follows.

A=F _x cosα+F _y sinα B=F _x ² +F _y ² Furthermore, by substituting equation (7) into equation (4), the following equation is obtained.

Here, the winding angle α, the number m, and the number of ropes N are known quantities, and the components F _x and F _y can be obtained from the strain gauges 24 _ax to 25 _dy , etc., as described above, so ( It is possible to determine the hanging load using equation 8).

FIG. 10 is a diagram showing force detection means of another hanging load detection device for a crane according to the present invention, and FIG. 11 is a sectional view taken along the line CC in FIG. 10. 30 _x1 in the figure
~31 _y2 is a strain gauge attached to the bottom of groove 23,
The strain gauges _30x1 to _31y2 are affixed to the axle 8 in such a direction as to detect strain in a direction perpendicular to the plane of FIG. 11. The strain gauges 30 _x1 to 31 _x2 are provided on the x-axis, and the strain gauges 30 _y1 to 31 _y2 are provided on the y-axis, and the strain gauges 30 _x1 , 31
_x1 , 30 _y1 , 31 _y1 and strain gauge 30 _x2 , 31 _x2 , 3
0 _y2 and 31 _y2 are provided a length l ₄ apart, and strain gauges 30 _x1 to 31 _x2 and strain gauge 30 _y
1 to 31 _y2 are respectively connected as shown in FIG. Note that a strain gauge is similarly attached to the groove 22, and wires are connected in the same manner.

In this force detection means, strain gauge 30 _x1 ~
The output e _px1 of the bridge composed of _31x2 is expressed by the following equation.

e _px1 =Kdl ₂ l ₄ /4EIl ₁ F _x e _i (9) Further, the output e _px2 of the bridge in the x-axis direction of the groove 22 is expressed by the following equation.

e _px2 = Kd (l ₁ − l ₂ ) l ₄ /4EIl ₁ F _x e _i (10) Then, the sum e _px of the output e _px1 and the output e _px2 is as shown in the following equation.

e _px = Kdl ₄ /4EIF _x e _i (11) In this way, the sum e _px is the component F _x of the force F in the x-axis direction.
The value will depend on the Further, the sum e _py of the outputs of the two bridges in the y-axis direction also has a value corresponding to the component F _y of the force F in the y-axis direction. Therefore, the sum e _px , e _py
The components F _x and F _y of force F can be determined separately from . In equation (11), the length l ₄ is always constant and is not related to the length l ₃ as in equation (3), so the positions of the reaction forces R ₁ and R ₂ change, Even if the length l ₃ changes, it is possible to accurately detect the x-axis component F _x (y-axis component F _y ) of the force F.

FIG. 13 is a diagram showing force detection means of another hanging load detection device for a crane according to the present invention, and FIG. 14 is a sectional view taken along line DD in FIG. 13. In the figure 32 _x1
~33 _y2 is the strain gauge attached to the bottom of the groove 23,
The strain gauges 32 _x1 to 33 _y2 are attached at an angle of 45 degrees to the axial direction of the access 8. The strain gauges 32 _{x1 to} 33 _x2 are provided on the y-axis, and the strain gauges _{32 y1} to 33 _y2 are provided on the x-axis _.
1 to 33 _y2 are connected as shown in FIG. 15, respectively. Note that a strain gauge is similarly attached to the groove 22, and wires are connected in the same manner.

In this force detection means, a force F is applied to the axle 8.
When the component F _x in the x-axis direction of
2 _x1 ~ 33 A principal strain occurs in the direction in which _x2 is pasted, and the value of the principal strain is half the principal shear strain of that part, that is, the shear strain due to bending, so the transverse elastic modulus of the axle 8 is Then, strain gauge 32 _x1 ~ 33 _x2
The output e _px1 of the bridge composed of is expressed by the following equation.

e _px1 =8Kl ₂ /3Gπd ² l ₁ F _x e _i (12) Further, the output e _px2 of the bridge in the x-axis direction of the groove 22 is expressed by the following equation.

e _px2 = 8K (l ₁ to l ₂ )/3Gπd ² l ₁ F _x e _i (13) Then, the sum e _px of the output e _px1 and the output e _px2 is as shown in the following equation.

e _px = -8K/3Gπd ² F _x ei (14) In this way, the sum e _px is the component F _x of the force F in the x-axis direction.
The value corresponds to Further, the sum e _py of the outputs of the two bridges in the y-axis direction also has a value corresponding to the component F _y of the force F in the y-axis direction. Therefore, the sum e _px , e _py
The components F _x and F _y of force F can be determined separately from . As can be seen from equation (14), the sum e _px
is not related to the length l ₃ , even if the positions of the reaction forces R ₁ and R ₂ change, the component F _x (component F _y ) of the force F can be detected accurately, and the 10th to 1st
In the force detection means shown in FIG. 2, it is necessary to accurately determine the length _l4 , but in this case, this is not necessary.

In the above embodiment, a strain gauge is used as the force detection means, but a magnetostrictive element, a piezoelectric element, etc. may also be used. Furthermore, in the above embodiment,
Although the guide sheave 9 is used as a means for keeping the winding angle α of the winding rope 10 around the top sheave 7 constant from the top sheave 7 to the winding drum 11, a guide plate or the like may also be used. In addition, when the wrapping angle α does not change much due to the elevation and elevation of the jib 3,
Although it is not necessary to use the guide sheave 9, if the guide sheave 9 is provided, the hanging load (tension T) can be determined more accurately.
It is possible to detect.

As explained above, in the hanging load detection device according to the present invention, the force acting on the axle of the top sheave is detected and the hanging load is calculated from the detected value, so the hanging load can be detected accurately and with simple calculation. can do. Furthermore, since there is no need to bend the take-up rope at a steep angle, the take-up rope will not be damaged. Furthermore, since the force detecting means is provided inside the top sheave portion, the appearance of the crane will not be damaged, and there is no risk that the force detecting means will be damaged by falling objects. Further, since the force acting on the axle of the top sheave is detected by disassembling it in the directions of two axes fixed to the jib, there is no need to provide an inclinometer. As described above, the effects of this invention are remarkable.

[Brief explanation of drawings]

Fig. 1 shows a crane with a conventional hanging load detection device, Fig. 2 shows an outline of a three-point roller type hanging load detection device, and Fig. 3 shows a crane with another conventional hanging load detection device. A diagram showing a crane, FIG. 4 is a diagram showing a part of the crane having a hanging load detection device according to the present invention, FIG. 5 is a sectional view taken along line A-A in FIG. 4,
Figure 6 is a sectional view taken along line B-B in Figure 5, Figure 7 is a wiring diagram of the strain gauge shown in Figure 6, and Figure 8 is the bridge shown in Figure 7 (Figures 12 and 15). Figure 9 is an explanatory diagram of the force acting on the axle.
FIG. 10 is a diagram showing force detection means of another crane hanging load detection device according to the present invention, and FIG.
C-C sectional view of figure 0, figure 12 is figure 10, figure 1
1 is a wiring diagram of the strain gauge shown in FIG. FIG. 15 is a wiring diagram of the strain gauges shown in FIGS. 13 and 14. 3... Jib, 7... Top sheave, 8... Axle, 9... Guide sheave, 10... Winding rope, 21a... Projecting piece, 21b... Knock pin,
22, 23...groove, 24 _ax ~25 _dy ...strain gauge, 30 _x1 ~31 _y2 ...strain gauge, 32 _x1 ~33 _y
2 ...Strain gauge.

Claims (1)

[Scope of Claims] 1. In a device for detecting the hanging load W of a crane, which has a jib that can be raised and raised about a foot pin, and a top sheave disposed at the tip of the jib, the axle of the top sheave cannot be rotated relative to the jib. A force detecting means is attached to the axle and detects the force acting on the axle by decomposing the force acting on the axle in the directions of the first and second axes fixed to the jib, and The detected values in the axial direction are F _x , F _y , the number of ropes on the top sheave is N, the number of winding ropes is m, the direction of the tension of the winding rope pulled in the direction of the winding drum and the first axis The angle formed with the direction, that is, the wrapping angle, is α, A = F _x cos α − F _y sin α,
When B=F _x ² + F _y ² , the following formula A hanging load detection device for a crane, characterized in that a calculation means for calculating the hanging load W from the above is provided. 2. The hanging load detection device for a crane according to claim 1, wherein the winding rope extending from the top sheave to the winding drum is hung on a guide sheave provided near the top sheave.