JPS6117367Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a device for measuring the swing angle of a load suspended by a crane. In order to quickly attenuate the swing of a crane suspended load and improve cargo handling efficiency, it is being considered to control the acceleration/deceleration speed of the trolley based on the magnitude of the swing of the hoisted load. This is necessary. A conventional device for measuring the swing angle of a suspended load is shown in FIG. This is the load L hanging on trolley 1.
A detection rod 3 is provided which can swing together with the rope 2 on which the rope 2 is suspended, and the deflection angle is measured by detecting the deflection displacement of the detection rod 3 with a displacement meter 4.
However, with this device, 1) the detection rod 3 cannot be made long, so the runout displacement is small and the accuracy is low; 2) minute vibrations occur in the contact area between the rope 2 and the detection rod 3, causing noise in the detection signal and accuracy. There are problems such as poor performance. Also, what is shown in Figure 2 is the hanging load L.
A mark 5 is placed on the trolley 1, and the deflection angle is measured by detecting the mark 5 with an optical position detector 6 provided on the trolley 1. However, this device has 1) non-contact measurements, so there is no noise due to contact, but the device is expensive.
2) Since it is an optical type, it is susceptible to the influence of surrounding brightness, and detection may not be possible in some cases. 3) Since the trolley 1 is equipped with an optical precision instrument, there are problems such as a short lifespan of the device due to vibration. be. This idea was devised in view of the above-mentioned circumstances, and its purpose was to provide a hydraulic damper to dampen the swing of a load suspended from two ropes suspended centrally in a V-shape from a trolley. It is an object of the present invention to provide a swing angle measuring device for a crane suspended load that can accurately and reliably measure the swing angle of the suspended load in a crane. The case where one embodiment of this invention is applied to the container crane shown in FIG. 3 will be described below.
The crane body 7 is provided with a boom 8 extending toward the sea, and a trolley 1 is moved along this boom 8, and a container C is moved by two ropes A and B suspended from the center in a V-shape from the trolley 1. The main body 7 can also be moved along the quay 9, and the motors for moving and hoisting are connected to the shore of the boom 8. It is provided in the machine room 10 on the side. This crane is provided with a hanging load steadying device as shown in FIGS. 4, 5, and 6, respectively. What is shown in Figure 4 is the machine room 1.
The two ropes A and B let out from the winding drum 11 of the boom 8 are wound around the pulleys 15 and 16 connected to the piston rods of the two oil field dampers 12 and 13 provided at the tip of the boom 8, and are wound onto the trolley 1. The rope is hung from a pair of rope pulleys 17 and 18 that are spaced apart from each other, and then hung from the center in a V-shape and wound around the lifting pulleys 19 and 20 of the container C, and the final end is attached to the land side of the boom 8. It is fixed at the end. And the above hydraulic damper 1
The cylinders 2 and 13 are connected to each other by hydraulic pipes 14 and 14 having damping valves 14a. Therefore, when the container C swings, the pistons of the hydraulic dampers 12 and 13 are displaced in proportion to the swing, and the dampers 12 and 1
Since a resistance proportional to the swing speed is applied to the container C, the swing of the container C can be stopped by appropriately adjusting the damping valve 14a. Further, in the one shown in FIG. 5, a pulley coupling body 26 including a pair of pulleys 24 and 25 is provided in the trolley 1 so as to be horizontally movable, and a hydraulic damper 27 having a damping valve 27a is fixed to the trolley 1. The piston rod of this damper 27 is connected to the pulley coupling body 26, and the way the ropes A and B are hung is almost the same as that shown in FIG. In this case, the pulley connection body 2
6 is displaced, the swinging of the container C is stopped by adjusting the damping valve 27a as in the case of FIG. Furthermore, in the one shown in FIG. 6, a fulcrum 28 is fixedly installed on the trolley 1, and a tilting body 29 is provided so as to be tiltable by supporting the central part on the fulcrum of the fulcrum 28. A pair of rope pulleys 17 and 18 are provided at the trolley 1, and both ends of the tilting body 29 are connected to piston rods of hydraulic dampers 30 and 31 fixed to the trolley 1.
Corresponding cylinders of both hydraulic dampers 30, 31 are connected by hydraulic arrangements 32, 33 having damping valves 32a, 32a, respectively. Further, ropes A and B are hung in substantially the same manner as shown in FIG. In this case as well, since the tilting body 29 tilts in proportion to the swing of the container C, the swing of the container C is stopped by adjusting the damping valves 32a, 32a as in the case of FIG. By the way, when the above three types of steady restraint devices shown in FIGS. 4 to 6 are modeled, the result is shown in FIG. 7. Here, d: Trolley position m: Container mass x: Container horizontal position y: Container vertical position l ₁ : Left rope hanging length l ₂ : Right rope hanging length ₁ : Left rope hanging angle ₂ : Right rope hanging angle c: Cable Interval between hanging pulleys x _P : Damper piston displacement T ₁ : Left rope tension T ₂ : Right rope tension α: Rope elasticity ζ: Damper damping constant m _P : Damper piston mass g: Gravitational acceleration l ₀ : Rope when unloaded The force balance equation of the model is as follows. my=mg−T ₁ cos ₁ −T ₂ cos ₂ (1) mx=−T ₁ sin ₁ +T ₂ sin ₂ (2) l ₁ =l ₀ −xp+1/αT ₁ (3) l ₂ =l ₀ +xp+1/ αT ₂ (4) mxp=−ζxp+T ₂ −T ₁ (5) x=d+l ₁ sin ₁ (6) And if there is no swing of the container, l ₂ = l ₁ = l
Then, if ₁ = +Δ, ₂ = -Δ and approximation is performed under the condition that the swing angle Δ is small, and the variation ΔT of the rope tension is determined, ΔT ₁ = α (cl/2yΔ+xp) (7) ΔT ₂ = −α(cl/2yΔ+xp (8) where ΔT ₁ = T ₁ − T ₁₀ (T ₁₀ : Tension at rest (and T ₁ + T ₂ = T ₁₀ + T ₂₀ (T ₂₀ : Tension at rest) T ₁₀ = T ₂₀ ), so ΔT ₁ = T ₁ − T ₁ + T ₂ /2 = T ₁ − T ₂ /2 (9). On the other hand, in equation (5) above, , in the normal usage range, the inertia term m _P x _P is small compared to other terms and can be ignored. Therefore, equation (5) becomes ζx _P = T ₂ − _{T 1} (10). Substituting equations (7), (8), and (9), we get ζx _P =-2α(cl/2yΔ+x _P (11), so the deflection angle Δ is Δ=-2y/cl(ζx _P /2α+x _P ) ( 12) Here, we will explain how we obtained equations (7) and (8) by approximation from equations (1) to (6) above, with reference to Figure 11. From similarity ＜= ₂ ∴Ccos ₂ =l ₁ sin( ₁ + ₂ ) l ₁ =cos ₂ /sin( ₁ + ₂ )C(〓1) Similarly, l ₂ =cos ₁ /sin( ₁ + ₂ )C( 〓2) Substituting equations (〓1) and (〓2) into equations (3) and 4 and rearranging, we get T ₁ = α (l ₁ − _{l 0} + xp) = α [coscosΔ+sinsinΔ/
sin2 C-l ₀ +xp〕 (〓3) However, ₁ = +Δ ₂ = -Δ. Here, if the deflection angle Δ is small and Δ=0 and sinΔ=ΔcosΔ=1, then T ₁ =α[Ccos/sin2−l ₀ ] +αCsin/sin2Δ+αxp (〓4) Similarly, T ₂ =α[Ccos/sin2− l ₀ ] −αCsin/sin2Δ−αxp (〓5). Here, if the stationary terms (first term) are T ₁₀ and T ₂₀ , then T ₁₀ = T ₂₀ = α [Ccos/sin2-l ₀ ] (〓
6) Or, if the fluctuation terms are ΔT ₁ and ΔT ₂ , ΔT ₁ = αCsin/sin2Δ+αxp(〓7
) ΔT ₂ =−αCsin/sinΔ−αxp(〓8
) Here, from the figure, cos=y/l, ∴ΔT ₁ = αCsin/2sin cosΔ+αxp = αCl/2yΔ+αxp = α(Cl/2yΔ+xp (〓9)…(7) Similarly, ΔT ₂ = −αCl/2yΔ−Δxp = −α(Cl/2yΔ+xp) (〓10)…(8) is found. Then, the damper piston displacement x on the right side of equation (12) above
_P , rope pulley interval c, and rope suspension length l are provided with measuring instruments, and rope elasticity α and damper damping coefficient ζ
The swing angle Δ of the suspended load can be measured by setting , and calculating the above equation (12) using a calculator. For example, a differential transformer or an inductor is used as the measuring device 36 for measuring the damper displacement _xP , and the movable side of the measuring device 36 is connected to the piston rod of the damper as shown in FIG. 8 to measure the displacement. The piston displacement speed x _P can be obtained by differentially calculating the output signal of the piston displacement measuring device 36 . As a measuring device for the rigging pulley interval c, a measuring device that utilizes the rotational speed of a ball screw, which is generally used for adjusting the interval between the rigging pulleys 17 and 18, is used.
A tachometer is installed on the winding drum 11 as a measuring device for the rope suspension length l, and the rope suspension length l is measured by multiplying the number of rotations by the drum diameter. Next, rope elasticity α is calculated from α=AE/L (A: rope cross-sectional area, E: rope Young's modulus, L: rope length, which affects elasticity), but the rope's Young's modulus E increases with the number of uses. The rope length L, which affects the elasticity, is determined by the friction in each pulley (it is shorter than the total rope length), so it is set taking these conditions into consideration. Further, the damping coefficient ζ of the damper is given by the characteristics of the damping valve. The vertical position y of the container is

It is calculated from [Formula]. In addition, the deflection angle calculator 37 inputs the outputs and set values of each of the above-mentioned measuring instruments, and inputs the above-mentioned
It is used to calculate equation (12). Then, as shown in FIG. 9, the measurement values of the piston displacement x _P , the cable pulley spacing c, and the rope suspension length l are input into the deflection angle calculator 37, and the rope elasticity α
and the damper damping coefficient ζ are given as set values, and the swing angle Δ of the suspended load can be measured by calculating the above equation (12). Since the device for measuring the swing angle of a crane suspended load of this invention is as described above, it is possible to measure the swing angle of a suspended load more accurately than before and reliably without being affected by surrounding brightness, etc. Can be done.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of conventional swing angle measuring devices for different hanging loads, and FIG. 3 is a schematic explanatory diagram of a container crane to which the device of this invention is applied.
Figures 4 to 7 are explanatory diagrams and modeled explanatory diagrams of different hanging load stabilizing devices used in the container crane in Figure 3, and Figure 8 is an illustration of the device used in one embodiment of this invention. FIG. 9 is an explanatory diagram of the installation state of the piston displacement measuring device, FIG. 9 is an explanatory diagram of the deflection angle calculator, and FIG. 10 is an explanatory diagram when performing approximate calculation. 1... Trolley, 11... Winding drum, 17,
18... Cable pulley, 12, 13, 17, 30,
31... Hydraulic damper, 36... Piston displacement measuring device, 37... Deflection angle calculator.

Claims (1)

[Claim for Utility Model Registration] A pair of separated rope pulleys are provided to suspend two ropes fed out from a winding drum from a trolley in a V-shape at the center, and a hydraulic damper is provided to damp the swing of the suspended load. The crane was equipped with measuring instruments for the piston displacement x _P of the hydraulic damper, the spacing c between the rigging pulleys, and the rope suspension length l, and the outputs of these measuring instruments were input, and the rope elasticity α and damper damping coefficient ζ were set. and a swing angle calculator for calculating the swing angle Δ of the suspended load according to the formula: Δ=-2y/cl (ζx _P /2α+x _P ).