Lifting anti-shaking and positioning method

Abstract

The invention discloses a lifting anti-shaking and positioning method, and mainly relates to the technical field of material lifting. Comprising the following steps: S1, lifting a rope for lifting an object through a winding drum or a fixed pulley, and lifting the lifted object to a certain height; s2, in the initial state, the lifted objects are vertically downward; s3, the moving vehicle starts to move forwards in an accelerated mode from the static state; when a traveling crane and a ship unloader stop, a heavy object below can be just kept in a stable state, so that the parking position of the heavy object can be accurately controlled, the problem of positioning deviation caused by shaking is avoided, and the conditions of object damage and the like caused by shaking are also avoided. In addition, the movement distance of the lifted object can be accurately calculated, and the lifted object can be accurately placed at a designated position.

Description

Technical Field

[0001] The invention relates to the technical field of material hoisting, and in particular to a method for hoisting anti-shaking and positioning. Background Art

[0002] When lifting objects, the crane and ship unloader need to move forward and backward to lift the objects to different places. The objects hung under the crane and ship unloader trolley will inevitably shake during the movement. In order to park the objects in the designated position, it is necessary to give the objects a certain external force or wait for the objects to stabilize before parking. This is inefficient and the deviation from the predetermined parking position is relatively large. Summary of the invention

[0003] The purpose of the present invention is to solve the problems existing in the prior art and to provide a method for anti-shaking and positioning of lifting, which can keep the heavy objects below in a stable state when the crane and the ship unloader stop. In this way, the parking position of the heavy objects can be accurately controlled to avoid positioning deviations due to shaking, and to avoid damage to objects caused by shaking.

[0004] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for preventing shaking and positioning of lifting, comprising the steps of:

[0006] S1. Lift the rope for lifting objects through a drum or fixed pulley to lift the objects to a certain height;

[0007] S2, the initial state is that the hoisted object is vertically downward, the hoisted object is only affected by the tension of the lifting rope, and the deflection angle θ is 0;

[0008] S3, the mobile car starts to move forward from rest, and the acceleration of the mobile car is assumed to be a. At this time, the equilibrium position of the hanging object is Where g is the acceleration due to gravity. If the influence of other factors is not considered, taking the mobile vehicle as a reference, the hoisted object will perform a simple pendulum motion with an initial angle of 0 and an amplitude of θ.

[0009] S4, the time from when the mobile vehicle starts to accelerate forward horizontally to when the hoisted object reaches the swing balance position is recorded as t1, at which time the swing speed of the hoisted object relative to the mobile vehicle is recorded as v1, and the speed of the driving motor of the mobile vehicle is recorded as n1; then the acceleration movement is stopped immediately, so that the speed of the driving motor of the mobile vehicle is maintained at n1, t1 and v1 are calculated by the formula, and n1 is converted into the actual forward speed of the mobile vehicle;

[0010] S5, then let the hoisted object swing to the lowest point, and record the time of this process as t2. At this time, the speed of the driving motor of the mobile vehicle is set to n2; the value of t2 and the swing speed of the hoisted object at the lowest point are deduced from the above calculation results, and the speed of the vehicle is added to calculate the value of n2. The speed of the driving motor is kept at n2. At this time, the swing speed of the hoisted object relative to the mobile vehicle is 0, and the hoisted object runs at the same speed as the mobile vehicle and no longer shakes;

[0011] S6. When the hoisted object needs to stop, the speed of the driving motor of the mobile vehicle is first adjusted from n2 to n1 according to the original method. After t2 time, the swing angle of the hoisted object returns to the equilibrium position. At this time, the speed of the hoisted object relative to the hanging point of the mobile vehicle is v1. Then the mobile vehicle decelerates with acceleration a. After t1 time, the mobile vehicle stops and the hoisted object also stops swinging.

[0012] Regardless of whether the trolley is accelerating, running at a constant speed, or decelerating to a stop, the distance traveled in each period of time can be accurately calculated, so that the total travel distance can be calculated and the precise placement of the hoisted items can be controlled.

[0013] Preferably, in step S2, θ≤23.1°.

[0014] Preferably, the shaking of the hoisted object is regarded as a simple pendulum motion. When θ≥10°, the period of the simple pendulum is: When θ<10°, the period of the simple pendulum is

[0015] Preferably, when the hoisted object under the mobile vehicle reaches the equilibrium position for the first time, the forward moment generated by the gravity acceleration is: mal*cosθ, the moment generated by gravity is mgl*sinθ, and the restoring moment of the simple pendulum system is l is the distance from the bottom hanging point of the mobile vehicle to the center of gravity of the hoisted object, then:

[0016]

[0017] The angular acceleration of the pendulum is thus

[0018] because Then there is The t1 and the swing speed v1 of the hoisted object at the equilibrium position can be obtained.

[0019] Preferably, when the hoisted object swings from the equilibrium position to the lowest position, according to the law of conservation of energy Determine the speed of the weight when it swings to the lowest point, and calculate the time required for this process using the simple pendulum formula.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] During the heavy object lifting process, the present invention first allows the lifting objects (heavy objects) under the mobile vehicle of the crane or ship unloader to swing according to predetermined requirements. When the lifting objects need to stop, the mobile vehicle is operated in reverse order of the last operation according to the swinging of the heavy objects. When the mobile vehicle stops, the lifting objects below just keep a stable state. In this way, the parking position of the heavy objects can be accurately controlled to avoid positioning deviations caused by shaking, and to avoid damage to objects caused by shaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the force analysis diagram of the hoisted items;

[0023] Figure 2 It is a schematic diagram of the hoisted items in the initial state. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.

[0025] Example:

[0026] The mobile vehicle (trolley) under the crane and the ship unloader lifts the heavy objects (lifted items) through a slender steel wire rope. The movement after lifting is similar to that of a simple pendulum. The present invention uses the principle and formula of simple pendulum motion to analyze the movement of the heavy object in the front and rear horizontal directions after lifting.

[0027] For larger angles, θ≥10°, the period calculation of the simple pendulum can be approximately expressed as When the angle is small, θ<10°, the period of the simple pendulum is The error

[0028]

[0029] Table 1 Swing angle error table

[0030] θ <![CDATA[60 o ]]> <![CDATA[30 o ]]> <![CDATA[15 o ]]> <![CDATA[10 o ]]> <![CDATA[5 o ]]> η 0.0625 0.0167 0.0043 <![CDATA[1.90*10 -3 ]]> <![CDATA[4.76*10 -4 ]]>

[0031] From Table 1, we can see that when the maximum swing angle is 15 o If the error is within 1%, the maximum swing angle is controlled at 23.1 o At this time, the deviations calculated by the two methods are not large.

[0032] like Figure 1 As shown in the figure, a heavy object with a mass of mkg is hung under the mobile car (trolley) of the crane and ship unloader. It is known that the length from the hanging point of the trolley to the center of gravity of the heavy object is l meter, and the volume of the heavy object is ignored. It is known that the initial state of the mobile car (trolley) is static. When the mobile car moves forward horizontally with an acceleration of a, the angle between the hanging rope and the vertical direction is θ, then: x direction: Tsinθ+ma=0, y direction: Tcosθ+mg=0, and the result is

[0033]

[0034] The gravitational acceleration g is known to be 9.8 m / s 2 , the size of the offset angle θ can be calculated based on the acceleration a, or the value of the acceleration a can be calculated based on the offset angle.

[0035] If you want to control the offset to 23.1 o If the acceleration is within 4.18 m / s 2 Such acceleration can accelerate a stationary object to a speed of more than 10m / s in just 2.5 seconds. Such horizontal acceleration has exceeded the speed of most heavy lifting equipment.

[0036] If the error is further amplified, or by installing an inclinometer on the sling and a speed and acceleration sensor on the trolley to reduce the impact of the system error, the acceleration can be further improved. It can be seen that within the allowable error range, the swing period of the heavy object can be roughly calculated using the simple pendulum formula, or the swing period can be accurately calculated using complex formulas according to on-site requirements.

[0037] For the convenience of calculation, the present embodiment sets the reference point of the weight shaking at the equilibrium position. If the computing power of the controller allows, the reference point can also be set at other positions, or directly at the lowest position, and the speed v, time t and the speed n of the driving motor when the weight shakes to the reference point can be calculated by a more complex formula, and then the speed v, time t of the weight at the lowest point and the speed n of the driving motor of the mobile vehicle can be calculated. When starting, operate in sequence, and when stopping, operate in reverse order.

[0038] When the mobile car (trolley) of the crane or ship unloader is uniformly accelerated horizontally from rest, the direction of the resultant force it receives is the direction of the rope tension. When the hoisted object (heavy object) under the mobile car (trolley) reaches the equilibrium position for the first time:

[0039] The forward torque generated by the acceleration of gravity is: mal*cosθ, the torque generated by gravity is mgl*sinθ, and the restoring torque of the simple pendulum system is Then there is The angular acceleration of the pendulum is thus because Then there is The time t and the swing speed of the weight at the equilibrium position (relative to the trolley) can be calculated by solving differential equations based on the known conditions a, g and l. In industrial applications, in order to avoid complex calculations during the control process and affect the control efficiency of the controller, several practical data models can be calculated in advance according to the actual needs of the site. During operation, the data of the calculated model can be directly selected to operate the trolley through the controller, making the control more convenient and quick.

[0040] The time from when the mobile car (trolley) of the crane or ship unloader begins to accelerate forward horizontally to when the hoisted object (heavy object) reaches the swing equilibrium position for the first time is counted as t1, at which time the swing speed of the heavy object relative to the mobile car (trolley) is counted as v1, and the speed of the driving motor of the mobile car is n1. At this time, the movement of the mobile car (trolley) of the crane or ship unloader is immediately changed to make the mobile car (trolley) run at the same speed as the hoisted object (heavy object). This is very easy to achieve in industry. The frequency converter is first used to increase the frequency and time according to the preset value, and after reaching the preset value, the frequency converter is allowed to maintain the frequency for stable operation.

[0041] When the hoisted object (heavy object) swings from the equilibrium position to the lowest position, it can be simply considered that the hoisted object (heavy object) is doing a simple pendulum motion. According to the law of conservation of energy, The speed of the heavy object when it swings to the lowest point is obtained. Then the speed of the mobile car (trolley) is added, and this is the actual speed when the hoisted object (heavy object) reaches the lowest point. When the hoisted object (heavy object) is about to reach the lowest point, the speed of the mobile car (trolley) of the crane and the ship unloader is quickly controlled to reach the speed of the hoisted object (heavy object). At this time, the hoisted object (heavy object) and the mobile car (trolley) can keep moving forward synchronously and stably. The time of this process is t2. The speed of the heavy object relative to the trolley is v2, and the speed of the driving motor of the mobile car is stable at n2. At this time, the speed of v2 is 0. Of course, since there is a sudden change in the output speed of the inverter in this process, there must be deviations here, but in actual work, it can be solved by offsetting the range of the equilibrium position or correcting the output frequency of the inverter. At this time, it can still ensure that the hoisted object and the trolley run at the same speed without shaking.

[0042] The process of the crane and the ship unloader moving forward steadily and then stopping can be regarded as the reverse operation of the initial operation. First, the speed of the driving motor of the mobile car is quickly adjusted from n2 to n1. After t2 time, the swing angle of the hoisted object (heavy object) reaches the equilibrium position. At this time, the speed of the heavy object relative to the hanging point of the trolley is v1. Then, the acceleration data a used in the initial operation is used for deceleration. After time t1, the trolley stops and the heavy object also stops swinging. And the distance that the hoisted object (heavy object) moves forward during this operation is the same as the distance of the last accelerated forward movement. This distance can be obtained by calculation or actual measurement. The distance of the smooth operation in the middle can be directly obtained according to the formula, so when the hoisted object (heavy object) is hoisted from a specified position to another specified position, it is completely controllable through calculation, so that the heavy object can be hoisted to the specified position smoothly and effectively.

[0043] In the actual process, because the distance between the transported objects (heavy objects) and the hanging point is often long, usually more than 5 meters, and sometimes even up to 10 to 20 meters, the period of the swing of the heavy objects is also very long. Calculated at l = 5 meters, t has exceeded 4 seconds. In the first 0.1 to 0.2 seconds of acceleration, the heavy objects have not moved much, and the trolley has already run ahead. In order to make the heavy objects reach a faster speed, it is necessary to let the heavy objects swing to a higher position. At this time, the above formulas and principles can still be used to build a model to let the trolley run according to the specified requirements and achieve smooth operation.

[0044] Because the crane and the ship unloader are in operation, affected by the friction of the wire rope and the drum, the swing angle of the heavy object in the process of moving forward is not as large as imagined, which is conducive to control. During the swing process, the fulcrum of the drum or the fixed pulley will also move a little, but because the swing angle is not large, and the diameter of the drum or the fixed pulley is small compared to the length of the lifting wire rope, the deviation from the actual calculation is often not large, which can be ignored or solved by correcting the frequency.

[0045] In addition, due to the existence of calculation errors in actual vehicle passing, the time t and the speed of the drive motor can be corrected in the model to achieve deviation correction, making the crane and ship unloader more stable and effective when lifting heavy objects.

Claims

1. A method for preventing shaking and positioning of lifting, characterized in that: Includes steps: S1. Lift the rope for lifting objects through a drum or fixed pulley to lift the objects to a certain height; S2, the initial state is that the hoisted object is vertically downward, the hoisted object is only affected by the tension of the lifting rope, and the deflection angle θ is 0; S3, the mobile car starts to move forward from rest, and the acceleration of the mobile car is assumed to be a. At this time, the equilibrium position of the hanging object is Where g is the acceleration due to gravity. If the influence of other factors is not considered, taking the mobile vehicle as a reference, the hoisted object will perform a simple pendulum motion with an initial angle of 0 and an amplitude of θ. S4, the time from when the mobile vehicle starts to accelerate forward horizontally to when the hoisted object reaches the swing balance position is recorded as t1, at which time the swing speed of the hoisted object relative to the mobile vehicle is recorded as v1, and the speed of the driving motor of the mobile vehicle is recorded as n1; then the acceleration movement is stopped immediately, so that the speed of the driving motor of the mobile vehicle is maintained at n1, t1 and v1 are calculated by the formula, and n1 is converted into the actual forward speed of the mobile vehicle; S5, then let the hoisted object swing to the lowest point, and record the time of this process as t2. At this time, the speed of the driving motor of the mobile vehicle is set to n2. The value of t2 and the swing speed of the hoisted object at the lowest point are deduced from the above calculation results, and the speed of the vehicle is added to calculate the value of n2. The speed of the driving motor is kept at n2. At this time, the swing speed of the hoisted object relative to the mobile vehicle is 0, and the hoisted object runs at the same speed as the mobile vehicle and no longer shakes. S6. When the hoisted object needs to stop, the speed of the driving motor of the mobile vehicle is first adjusted from n2 to n1 according to the original method. After t2 time, the swing angle of the hoisted object returns to the equilibrium position. At this time, the speed of the hoisted object relative to the hanging point of the mobile vehicle is v1. Then the mobile vehicle decelerates with acceleration a. After t1 time, the mobile vehicle stops and the hoisted object also stops swinging. Regardless of whether the trolley is accelerating, running at a constant speed, or decelerating to a stop, the distance traveled in each period of time can be accurately calculated, so that the total travel distance can be calculated and the precise placement of the hoisted items can be controlled.

2. A method for anti-swaying and positioning of lifting according to claim 1, characterized in that: In step S2, θ≤23.1°.

3. A method for anti-swaying and positioning of lifting according to claim 1, characterized in that: The sway of the hoisted object is regarded as a simple pendulum motion. When θ≥10°, the period of the simple pendulum is: When θ<10°, the period of the simple pendulum is 4. A method for anti-swaying and positioning of lifting according to claim 1, characterized in that: When the hoisted object under the mobile vehicle reaches the equilibrium position for the first time, the forward torque generated by the acceleration of gravity is: mal*cosθ, the torque generated by gravity is mgl*sinθ, and the restoring torque of the simple pendulum system is l is the distance from the bottom hanging point of the mobile vehicle to the center of gravity of the hoisted object, then: The angular acceleration of the pendulum is thus because Then there is The t1 and the swing speed v1 of the hoisted object at the equilibrium position can be obtained.

5. A method for anti-swaying and positioning of lifting according to claim 1, characterized in that: When the hoisted object swings from the equilibrium position to the lowest position, according to the law of conservation of energy Determine the speed of the weight when it swings to the lowest point, and calculate the time required for this process using the simple pendulum formula.

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