Crane stop-time shaking stop control method

Abstract

To provide a crane stop-time shaking stop control method capable of grasping a shaking state after a target position stop and stopping shaking with the minimum moving distance without veering from a target stop position.SOLUTION: After a target position of a crane has been reached, a shaking period T[s] and a shaking width D[mm] are measured from a rope length L[mm] and a shaking angle θ[°] in a state where the crane is temporarily stopped. On the basis of the shaking period T[s] and the shaking width D[mm] that have been measured, the number of inching times n[times], an inching frequency f[Hz], inching time t[s], an inching moving distance r[mm], and a suppression shaking width d[mm] that an inverter of an inching table prepared in advance gives to a motor are selected and set as parameters. An inching operation is performed with an inching operation based on the selected and set parameters and an inching operation having the same inching frequency f[Hz], the same inching time t[s] and an opposite inching direction as a set.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for controlling sway prevention during crane stoppage, which performs both sway prevention and positioning after the crane has reached its target position. [Background technology]

[0002] Conventionally, anti-sway control of a crane is performed in accordance with the phase plane trajectory (see, for example, Patent Document 1). In particular, automated cranes must perform both sway prevention and positioning when they reach the target position. Specifically, once the crane reaches the target position and the conditions for position accuracy, including both the preset position deviation value and swing width, are below a certain value, the load can be lowered. The crane's position accuracy, which is the sum of the position deviation value and swing width, is set to a preset value of, for example, ±100 mm. Anti-sway control that matches the phase plane trajectory adjusts the motor speed to the angle and angular velocity on the phase plane trajectory, and controls the inverter frequency to accelerate, maintain a constant speed, or decelerate to control the posture so that the load does not sway.However, when the mechanical brake is used frequently, delays in operation occur due to changes in frictional resistance, and the crane must wait for the sway to stop after stopping, resulting in reduced work efficiency. Furthermore, with manual cranes, acceleration and deceleration are performed at the timing set by the operator, regardless of the phase plane trajectory, which causes swinging after the crane stops, requiring a wait for the swinging to stop, resulting in reduced work efficiency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-056394 Summary of the Invention [Problem to be solved by the invention]

[0004] In view of this problem, an object of the present invention is to provide a sway prevention control method for stopping a crane, which grasps the sway state after stopping at a target position, and performs sway prevention with the minimum movement distance without deviating from the target stopping position, regardless of whether the crane is automatic or manual. [Means for solving the problem]

[0005] In order to achieve the above object, the anti-sway control method for a crane when stopping according to the present invention comprises: A sway prevention control method for a crane when the crane is stopped, which performs sway prevention and positioning together after the crane reaches a target position, After the crane reaches the target position, the crane is stopped temporarily, and the swing period T [s] and swing width D [mm] are measured from the rope length L [mm] and swing angle θ [°], Based on the measured vibration period T [s] and vibration width D [mm], the number of inchings n [times], inching frequency f [Hz], inching time t [s], inching movement distance r [mm], and suppressed vibration width d [mm] are selected and set as parameters, which are to be applied to the motor by the inverter of the inching table prepared in advance, The inching operation based on the selected and set parameters is performed as a set of inching operations with the same inching frequency f [Hz] and inching time t [s] but in the opposite inching direction. It is characterized by: Here, the inching operation can be performed two or more times (one set) or more times (four or more even times).

[0006] In this case, the inching operation can be performed in the swing direction from the timing when the swing angle θ [°] passes through 0°.

[0007] Furthermore, the measured swing width D [mm] can be the maximum swing width measured during a swing period of 1T [s] for a rope length L [mm] when the crane is temporarily stopped. [Effects of the Invention]

[0008] According to the anti-sway control method for crane stop of the present invention, whether the crane is automatic or manual, the state of sway can be grasped after stopping at the target position, and anti-sway can be performed within the minimum travel distance without deviating from the target stopping position, thereby shortening the wait time for the sway to stop after the crane has stopped, and improving the work efficiency of cargo handling work using the crane. More specifically, if the sway width of the load after stopping at the target position exceeds, for example, ±50 mm, anti-sway control can be performed within the minimum travel range, which makes anti-sway control possible even when the load is set in a narrow range such as a mold, or when the load is close to a wall. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a system configuration diagram of a crane for implementing a method for controlling the anti-sway of a crane when the crane is stopped according to the present invention. [Figure 2] FIG. 10 is an explanatory diagram of the anti-sway control including the mechanical brake in the anti-sway control method for stopping the crane of the present invention. [Figure 3] 1 shows measurement data obtained by implementing the anti-sway control method for stopping a crane according to the present invention. [Figure 4] FIG. 1 is an explanatory diagram of measurement data obtained by implementing the anti-sway control method for stopping a crane according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a method for controlling anti-sway during crane stoppage according to the present invention will be described with reference to the drawings.

[0011] FIG. 1 shows an example of a crane system configuration for implementing the anti-sway control method for stopping a crane of the present invention, and FIG. 2 shows an example of anti-sway control including a mechanical brake. The system configuration of this crane is commonly used in overhead cranes. In Figure 1, crane control panel 1 is connected to hoisting motor 2, traverse motor 3, traveling motor 4, hoisting brake 5, traverse brake 6, traveling brake 7, hoisting limit switch 8, traverse limit switch 9, traveling limit switch 10, hoisting encoder 11, traverse encoder 12, traveling encoder 13, and sway angle sensor 14 to control each device.

[0012] Here, the control method of the crane is inverter control, and after the crane stops at the lateral or travel target position, the rope length detected by the hoisting encoder 11 and the maximum swing width are measured from the swing angle sensor 14.

[0013] For anti-sway control, setting data is created in advance for the items in the inching table shown in Table 1, and the speed (frequency) and time of the first and second inching for the rope length and sway angle are measured.

[0014] [Table 1]

[0015] As parameters for the inching table, when the crane is stopped, the swing period T [s] and swing width D [mm] are calculated from the rope length L [mm] and swing angle θ [°], and the number of inchings n [times] that the inverter will give to the motor, the inching frequency f [Hz], the inching time t [s], the inching travel distance r [mm], and the suppressed swing width d [mm] are set.

[0016] The swing width D [mm] is calculated from the amount of rotation of the hoisting encoder 11, the rope length L [mm] to the load, and the swing angle θ [°] of the swing angle sensor 14, as follows: D=L×tan θ [mm]. The swing period T [s] is calculated from the rope length L [mm] as T = 2π((L / 1000)g) 1 / 2 (where g is the acceleration due to gravity). The inching movement distance r [mm] is determined by measuring in advance the minimum inverter frequency f [Hz] and inching time t [s] that allow inching in the direction of movement per cycle at the rated load, and registering the suppressed swing width d [mm] by inching as an inching table. Two inching operations are registered as a set, and the second inching is given the same minimum frequency f [Hz] and inching time t [s] in the opposite direction to the first inching, allowing the crane to return to its original position with the minimum movement distance and suppress swing. The number of inching movements is determined by the maximum swing amplitude when the crane is stopped, and the swing amplitude D [mm] measured after the crane arrives at the destination position and stops is divided by the suppressed swing amplitude d [mm] suppressed by inching, giving the number of inching movements n = D / d [times]. Here, in order to keep the target sway width within the desired set value (target sway width), the control amount for sway prevention control is set to 1 / 10 of the target sway width and the resolution of the sway angle sensor is set to 0.01 (capable of detecting a sway angle of 0.01°). For example, if the target sway width is ±50 mm, the control amount will be 5 mm, which is 1 / 10 of the target sway width, and if the maximum rope length that can be controlled by inching operation is Lmax, the maximum rope length will be 28.6 m, as Lmax = 5 / tan(0.01). In addition, if the swing angle is detected to be greater than the set maximum allowable swing angle, an emergency stop will be performed to prevent contact between the wire rope and the crane body. Inching operation is performed by the crane following the direction in which the load is swinging to stop the sway. The same inching frequency and inching time are set for the first and second inching operations, as the crane must return to the target stop position where it stopped when the inching operation is completed, and the first and second inching directions are opposite. The timing of the first inching is measured based on the timing when the brake is closed after the crane has stopped, and the maximum swing width (peak-to-peak) is measured during the swing period of 1T [s] (1T is shown in Figure 2; the same applies below) relative to the rope length. The maximum swing width (peak-to-peak) is calculated from the position and vector relative to the rope length. This is done by either calculating the maximum swing width from the square root or the swing angle. After measuring the maximum swing width between S and G in Figure 2 for a swing cycle of 1T [s] after the brake is closed, the corresponding first and second inching frequencies, inching time, and number of inching movements are determined from the inching table in Table 1. The first inching operation is performed in the swing direction from timing A in Figure 2, when the swing angle passes 0° for the first time during the swing cycle 2T [s] in Figure 2. Next, the second inching operation is performed at timing B in Figure 2, when the swing angle passes 0° half a cycle after the 2T [s] cycle, making it possible to achieve both alignment at the target stop position and swing prevention.

[0017] In the case of a manual crane, a pushbutton switch (e.g., an anti-sway button) for executing the anti-sway control method of the present invention is added to the crane's operating device, and an indicator indicating that anti-sway control is in progress is installed in a location easily visible to the operator operating the crane. When the crane is stopped, the indicator indicating that anti-sway control is in progress flashes (or may simply light up) only while the anti-sway button is pressed, and inching operation is enabled. The maximum swing amplitude is measured during a swing cycle of 1T [s] between S and G from the time the anti-sway button is pressed, and the number of inching operations is determined. The first inching operation is performed when the swing angle passes 0° for the first time at 2T [s], and the second inching operation is performed when the swing angle passes 0° 1 / 2 cycle later. When the swing amplitude is within the set value, the indicator indicating that anti-sway control is in progress turns off, allowing the operator to determine that lowering is possible.

[0018] Figure 3 shows a graph of the actual measurement data from an experiment in which the crane rope length was 6,900 mm, the travel speed was 60 m / min, the target swing width was ±50 mm, and the target position was 18,000 mm. Swing occurred after the crane stopped at the target position, and sway control was performed after the crane stopped. The frequency and speed command values ​​have been converted to make it easier to visualize the numerical data inside the PLC, converting from 400 to 50 Hz to 100 m / min. The vertical axis on the left side of Fig. 3 represents the values ​​for the sway angle, sway amplitude, forward travel, reverse travel, and travel brake (Br). The units are converted from 1 to 0.01° for the sway angle and from 1 to 1 mm for the sway amplitude. Forward travel and reverse travel are ON when in operation and OFF when stopped, and the operating state of the travel brake (Br) is indicated by the brake being open or closed.

[0019] When the anti-sway control method for crane stop of the present invention is actually applied to a crane, an inching table such as that shown in Table 2 (FIG. 4 is an explanatory diagram) for that crane is created for each rope length. To create the inching table, the minimum inverter frequency and minimum inching time that allow the motor to perform inching are measured using the crane with the rated load hoisted as shown in FIG. 4. The example in FIG. 4 is for a rope length of 6900 mm. Measurements are taken with the rated load hoisted at a rope length of 6900 mm and a swing width of 105 mm. As a result, the frequency and inching time that allow inching operation are derived, and the travel distance and suppressed swing width for this inching state can be determined. The inching table shown in Table 2 is created based on these measurement results. In this way, the inching table in Table 2 is created for each rope length, but the rope length interval can be determined appropriately depending on the specifications of the target crane, for example, at intervals of 100 mm, 200 mm, 500 mm, etc.

[0020] [Table 2]

[0021] The measured data shown in Figure 3 shows that the crane travels in the reverse direction with a target stopping position of 18,000 mm, and stops after about 18 seconds, and at the timing when the brakes are applied, the angle of the load is swinging to the right (reverse direction). After arriving at the target position, the swing period is measured for one cycle of 5.26 seconds, and the peak-to-peak swing width is determined. Next, the first inching is performed in the forward (reverse direction) direction at 2.08 Hz and a timing of 0.58 seconds, starting from 23.86 seconds when the swing angle is 0 and the angular velocity is at its maximum. After that, the second inching timing is performed in the reverse (forward) direction at 2.08 Hz for 0.58 seconds when the swing angle passes 0° after 1 / 2 cycle, and the swing width becomes ±50 mm or less, completing the swing prevention.

[0022] In this example, two inching operations were performed to reduce the swing amplitude to within ±50 mm of the target value and complete the swing control. However, as shown in Table 2, if the swing amplitude is large, by performing the inching operation an even number of times (two or more), swing control can be performed with the minimum movement distance without deviating from the target stopping position.

[0023] The above has described the anti-sway control method for stopping a crane according to the present invention based on its embodiments, but the present invention is not limited to the configurations described in the above embodiments, and the configuration can be changed as appropriate within the scope of the spirit of the present invention. [Industrial Applicability]

[0024] The anti-sway control method for stopping a crane of the present invention enables anti-sway control in a narrow work area, and therefore can be widely applied to automatic cranes whose operation is controlled by a crane control PLC, as well as to manual cranes, making it useful in industry. [Explanation of symbols]

[0025] 1 Crane control panel 2 Hoisting motor 3 Traverse motor 4. Travel motor 5 Hoisting brake 6 Traverse brake 7. Driving brake 8 Hoisting limit switch 9 Traverse limit switch 10 Travel limit switch 11 Winding encoder 12 Traverse Encoder 13 Travel encoder 14 Deflection angle sensor

Claims

1. A sway prevention control method for a crane when the crane is stopped, which performs sway prevention and positioning together after the crane reaches a target position, After the crane reaches the target position, the crane is stopped temporarily, and the swing period T [s] and swing width D [mm] are measured from the rope length L [mm] and swing angle θ [°], Based on the measured vibration period T [s] and vibration width D [mm], the number of inchings n [times], inching frequency f [Hz], inching time t [s], inching movement distance r [mm], and suppressed vibration width d [mm] of the inching table prepared in advance are selected and set as parameters. The inching operation based on the selected and set parameters is performed as a set of inching operations with the same inching frequency f [Hz] and inching time t [s] but in the opposite inching direction. A method for controlling anti-sway during crane stoppage.

2. 2. The method for controlling anti-sway during crane stop according to claim 1, wherein a plurality of sets of the inching operation are performed.

3. 3. The method for controlling anti-sway during crane stop according to claim 1, wherein the inching operation is performed in the swing direction from the timing when the swing angle θ [°] passes through 0°.

4. A method for controlling anti-sway control when a crane is stopped according to claim 1 or 2, characterized in that the measured sway width D [mm] is the maximum sway width measured during a sway period of 1T [s] for a rope length L [mm] when the crane is temporarily stopped.

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