JPH0358996B2 - - Google Patents

Description

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

FIG. 1 is a diagram showing a crane having a conventional moment detection device. In the figure, 1 is an undercarriage, 2 is an upper revolving body which is rotatably attached to the lower revolving body 1, 3 is a jib which is attached to the upper revolving body 2 by a foot pin 4 so that it can be depressed, 5 is a restraining rope, 6 is a depression drum, 7 is a top sheave placed 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 a winding drum, 12 a hook suspended by the winding rope 10, 13 a load suspended from the hook 12,
14 is a three-point roller type hanging load detection device, and 20 is an inclinometer that detects the inclination angle of the jib 3.

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. On the other hand, due to the inclination angle of the jib 3, the foot pin 4
Find the length from to the line of action (vertical line) of the hanging load. Then, by multiplying the hanging load and the above length, the moment due to the hanging load is determined. However, in order to improve the detection accuracy of the hanging load detection device 14, it is necessary to
It is necessary to make the angle θ between the two sides as small as possible, but if the angle θ is too small, the take-up rope 10 will be bent three times at a steep angle, resulting in severe damage to the take-up rope 10. In addition, the winding rope 10
Since a frictional force acts between the sheaves 15 and 17, the moment (tension T) cannot be detected accurately. Furthermore, since the hanging load detection device 14 is arranged at 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. Also, in order to find the length from the foot pin 4 to the line of action of the hanging load,
It is necessary to provide an inclinometer 20. Furthermore, since the moment due to the hanging load is not directly detected, but the moment is obtained by multiplying the hanging load by the length from the foot pin 4 to the line of action of the hanging load, complex calculations must be performed. Therefore, detection accuracy is low. Furthermore, during crane work, the direction of the line of action of the hanging load is not necessarily vertical due to centrifugal force during swing operation, wind force, and the like. For this reason, as shown in FIG. 3, for example, when the load 13 is swung outward, the length from the foot pin 4 to the line of action of the force due to the hanging load is
L ₁ is the length L ₂ from foot pin 4 to vertical line V
, and the moment due to the hanging load increases. Therefore, by multiplying the hanging load by the length from the foot pin 4 to the vertical line V, it is impossible to accurately determine the moment when the line of action of the hanging load is not vertical.

FIG. 4 is a diagram showing a crane having another conventional moment detection device. In this moment detection device, a load cell 19 is provided to detect the tension of the vibration suppression rope 5, and the hanging load is calculated by multiplying the tension of the vibration suppression rope 5 by the length from the foot pin 4 to the line of action of the tension of the vibration suppression rope 5. We are looking for the moment due to etc. However, since the vibration suppression rope 5 forms a curve called a catenary line, the load cell 1 of the curve
Unless the tangent a at point 9 is found, the length from the foot pin 4 to the line of action of the tension on the vibration damping rope 5 cannot be found accurately, but it is difficult to actually measure or calculate this. The above length is calculated assuming that the vibration suppressing rope 5 is a straight line as shown by the two-dot chain line. Therefore, moment detection accuracy is low.

This invention was made to solve the above-mentioned problems, and it is possible to accurately detect the moment due to the hanging load, without damaging the take-up rope, and without damaging the appearance of the crane. It is an object of the present invention to provide a moment detection device for a crane that does not require the installation of an inclinometer, can determine the moment with simple calculations, and can accurately detect the moment even when the line of action of a suspended load is not vertical. .

In order to achieve this object, the present invention provides a device for detecting a moment M due to a hanging load of a crane, which has a jib that can be depressed around a foot pin, and a top sheave disposed at the tip of the jib. An axle is non-rotatably attached to the jib, and a force detection means is provided for detecting the force acting on the axle by disassembling it in the directions of the first and second axes at right angles fixed to the jib. The detected values in the first and second axis directions are
F _x , F _y , the number of ropes on the top sheave is N,
The length of the line connecting the center of the foot pin and the center of the axle is L, 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 axial direction. When the angle formed by the winding angle is α, A=F _x cosα−F _y sinα, and B=F _x ² + F _y ² , the following formula Calculating means for calculating the moment M from the above is provided.

FIG. 5 is a diagram showing a part of a crane having a moment detection device according to the present invention, FIG. 6 is a cross-sectional view taken along line AA in FIG. 5, and FIG. 7 is a cross-sectional view taken along line B-B in FIG. 6. . 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 and 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 _a
x , 24 _ay , 25 _ax , 25 _ay are active strain gauges attached to the bottom of the groove 23, 24 _dx , 24 _dy , 25 _d
x , 25 _dy are dummy strain gauges for temperature compensation attached to the side of the groove 23, and strain gauges 24 _ax , 24
_dx , 25 _ax , 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 , 2
5 _dy is provided on the axis perpendicular to the x-axis, that is, the y-axis. And active strain gauge 24 _ax ,2
4 _ay , 25 _ax , and 25 _ay are attached in a direction to detect distortion in a direction perpendicular to the plane of FIG. 7 on the axle 8. 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. 8, respectively. Note that the strain gauges attached to the grooves 22 are also wired in the same way.

In the force detection means of this moment detection device, as shown in FIG. 9, when a force F _xp in the x-axis direction is applied to the axle 8, the strain gauge 24 _ax expands, the strain gauge 25 ax contracts, and the strain gauge 25 _ax contracts. gauge 24
_dx , 25 _dx is not deformed. At this time, the strain sensitivity (constant) of the strain gauge is K, the vertical elastic modulus of the axle 8 is E, and the second moment of area of the groove 22 is I,
The diameter of the groove 22 is d, and the jib 3 relative to the axle 8 is
The length between the points of action of the reaction forces R ₁ and R ₂ from l ₁ is the reaction force
The length between the point of application of R ₂ and the point of application of force F _xp is l ₂ ,
When the length between the point of application of the reaction forces R ₁ and R ₂ and the center of the grooves 23 and 23 is l ₃ , the output e _px1 of the bridge composed of the strain gauges 24 _ax to 25 _dx is expressed by the following equation.

e _px1 =Kdl ₂ l ₃ /EIl ₁ F _xp e _i (1) 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 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 position of the point of action of force F _px , the sum e _px has a value that corresponds to force F _xp . On the other hand, since the strain gauges 24 _ay and 25 _ay in the y-axis 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. 10 is an explanatory diagram of the force used 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, when equation (7) is substituted into equation (4), the following equation is obtained.

Further, if the length of the line connecting the center of the foot pin 4 and the center of the axle 8 is L, the moment M around the foot pin 4 due to the hanging load W is expressed by the following equation.

M=WLsinβ (9) From equations (6), (8), and (9), the moment M becomes as shown in the following equation.

Here, the number of ropes N, length L, number m, and wrapping angle α 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. Therefore, it is possible to obtain the moment M using equation (10). In equation (10), the angle β between the x-axis and the line of action of the force mT is not related, so even if the line of action of the hanging load W is not vertical, the moment M cannot be detected accurately. can.

FIG. 11 is a diagram showing force detection means of another crane moment detection device according to the present invention, and FIG. 12 is a sectional view taken along the line CC in FIG. 11. In the figure 3
0 _x1 to 31 _y2 are strain gauges attached to the bottom of the groove 23, and strain gauges 30 _x1 to 31 _x2 are the first strain gauges of the axle 8.
It is pasted in the direction to detect distortion in the direction perpendicular to the paper surface of Figure 2. The strain gauges 30 _x1 to 31 _x2 are provided on the x-axis, and the strain gauges 30 _y1 to 31
_y2 is provided on the y-axis, and strain gauges 30 _x1 ,
31 _x1 , 30 _y1 , 31 _y1 and strain gauge 30 _x2 , 31 _x
2 , 30 _y2 , and 31 _y2 are provided a length l ₄ apart, and strain gauges 30 _x1 to 31 _x2 and strain gauges 30 _y1 to 31 _y2 are 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 (11) 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 ₄ F _x e _i (12) 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 (13) 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, sum e _px , e _py
The components F _x and F _y of force F can be determined separately from . In equation (13), 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, length l ₃
Even if changes, the x-axis component of force F _x
(component F _y in the y-axis direction) can be detected accurately.

FIG. 14 is a diagram showing force detection means of another crane moment detection device according to the present invention, and FIG. 15 is a sectional view taken along line DD in FIG. 14. In the figure 3
2 _x1 to 33 _y2 are strain gauges attached to the bottom of the groove 23, and the strain gauges 32 _x1 to 33 _y2 are attached at an angle of 45 degrees with respect 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. _y2 are 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, 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 (14) 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 − l ₂ )/3Gπd ² l ₁ F _x e _i (15) 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 e _i (16) 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, sum e _px , e _py
The components F _x and F _y of F can be found separately. As can be seen from equation (16), the sum e _px
is not related to the length l ₃ , so 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 accurately detected, and the 11th to 1st
In the force detection means shown in FIG. 3, 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 wrap angle α does not change much due to depression of the jib 3,
Although it is not necessary to use the guide sheave 9, if the guide sheave 9 is provided, it is possible to detect the moment (tension T) more accurately. Furthermore, the hanging load W may be obtained from equation (8), and in this case, both the moment M and the hanging load W can be detected by one force detection means.

As explained above, the moment detection device according to the present invention detects the force acting on the axle of the top sheave and calculates the moment due to the hanging load from the detected value, so the moment 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. moreover,
Since the force detection 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 detection 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. Furthermore, even if the line of action of the hanging load is not vertical, the moment can be detected accurately, so falling can be effectively prevented and crane work can be performed safely. As described above, the effects of this invention are remarkable.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a crane with a conventional moment detection device, Fig. 2 is a diagram showing an outline of a three-point roller type hanging load detection device, and Fig. 3 is an explanation of the moment detection device shown in Fig. 1. 4 is a diagram showing a crane having another conventional moment detection device, FIG. 5 is a diagram showing a part of a crane having a moment detection device according to the present invention, and FIG.
AA sectional view in the figure, FIG. 7 is a BB sectional view in FIG. 6, FIG. 8 is a wiring diagram of the strain gauge shown in FIG. 7,
Fig. 9 is an explanatory diagram of the output of the bridge shown in Fig. 8 (Fig. 13, Fig. 16), Fig. 10 is an explanatory diagram of the force acting on the axle, and Fig. 11 is an illustration of another crane according to the present invention. 12 is a sectional view taken along the line C-C in FIG. 11,
FIG. 13 is a wiring diagram of the strain gauge shown in FIGS. 11 and 12, and FIG. 14 is a diagram showing force detection means of another crane moment detection device according to the present invention.
15 is a sectional view taken along the line DD in FIG. 14, and FIG. 16 is a wiring diagram of the strain gauges shown in FIGS. 14 and 15. 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 a moment M due to a hanging load of a crane, which has a jib that can be lifted up and down about a foot pin, and a top sheave placed at the tip of the jib, an axle of the top sheave is attached to the jib. The jib is mounted non-rotatably and the force acting on the axle is transferred to the first and second perpendicular jib fixed to the jib.
A force detection means is provided to detect the force by disassembling it in the axial direction.
The detected values in the first and second axial directions of the force detection means are F _x and F _y , the number of ropes of the top sheave is N, and the length of the line connecting the center of the foot pin and the center of the axle is L, the number of winding ropes is m,
The angle between the direction of tension of the take-up rope pulled in the direction of the take-up drum and the above-mentioned first axis direction, that is, the winding angle, is α, A = F _x cos α - F _y sin α, B = F _x ² + F _y
² , the following formula A moment detection device for a crane, characterized in that a calculation means is provided for calculating the moment M from . 2. The crane moment detection device 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.