JP7423882B2 - Bucket grip control method - Google Patents

Description

The present invention provides a crane hoisting device consisting of two independent hoisting devices, a supporting device and an opening/closing device, and a multi-rope bucket that is moved by two types of ropes, a supporting rope and an opening/closing rope, suspended from the hoisting device. (In this specification, it may be simply referred to as a "bucket.") The present invention relates to a control method for performing a grasping operation of a bucket in a crane equipped with a bucket.

When grasping a bucket, in order to grasp a large amount of bulk material (garbage, ash, dust, cement, other powder and granules, etc.), the bucket is grasped while sinking into the bulk material under its own weight. There is a method for doing this (herein simply referred to as a "sinking and grabbing control method").
This sink grip control method maintains a state in which the support motor continues to generate torque in the hoisting direction with a low torque just enough to take up the slack in the rope, while the opening/closing motor generates motor torque to hoist in the hoisting direction. It will be done.
When the support rope is slack, the support rope is wound up, and when the support rope is stretched, the low torque of the support motor is overcome by the pull of the bucket's own weight, and the support rope is unwound, allowing the bucket to rest on top of the bulk material. The bucket's own weight is applied, and the claws of the bucket dig in and sink as it performs the grasping motion.
With this sinking and grabbing control method, more loose cargo can be stored in the bucket, and a predetermined amount of grasping can be ensured.

Another method for performing a sinking grab operation is to lower or wind up the rope at low speed depending on the opening/closing position without reducing the torque of the support motor. Grabbing must be done under uniform conditions with a constant amount of sinking, and a low-torque sinking grip control method that allows a large amount to be grabbed regardless of the slack state of the rope at the beginning of the grip or the amount of sinking is an advantage. There is.
However, the sinking gripping method, which uses a low torque support motor, can cause the bucket to stall and fall if you mistakenly perform a gripping operation when the bucket is suspended in the air, or the bucket toppling over when trying to grip a slope, or to loosen the bucket. However, there was a need for improvement in that it took time to wind up the support rope.

In order to deal with this problem, for example, in Patent Document 1, as a method of preventing the bucket from falling when trying to grasp the slope, the support brake is closed when the amount of the support rope that is let out exceeds a certain amount. Although a method has been described, since it is not possible to take up the slack after the brake is closed, this method still has the problem that slack remains in the support rope.

Japanese Unexamined Patent Publication No. 61-101394

In this way, with the conventional control method that simply reduces the torque of the support motor to take up the slack in the support rope in order to make the bucket sink and grab, it is possible to accidentally grab the bucket when the bucket is suspended in the air. If this happens, the winding torque of the support is weak, causing problems such as the bucket stalling and falling, or when attempting to grab a sloped area where loose cargo is piled up, the support rope will not be able to hold on. There was an issue with the bucket easily tipping over.

Regarding the problem that the bucket tends to fall when trying to grab a sloped place, Patent Document 1 describes a method of closing the support brake when the amount of the support rope that is let out exceeds a certain amount. Since it was not possible to take up the slack after the brake was closed, the problem remained that the support rope remained slack.

Furthermore, in the conventional method of simply reducing the torque of the support motor to a low torque, the support motor is rotated in the direction in which the support rope is fed out when the bucket sinks, but at this time, the rotating parts of the support motor and support brake are Inertial force is generated in the direction in which the support rope is fed out, but since the torque of the support motor is low and the resistance to the inertial force is small, it takes time to stop the rotation due to the inertial force, and during that time, the support rope is fed out excessively. Put it away.
In this way, there is a problem in that an extra support rope is unwound and it takes extra time to wind it up.

The present invention solves the problems of stalling and falling of the bucket and overturning of the bucket caused by low-torque control of the support motor in sinking and grasping control of a multi-rope type bucket. The purpose of the present invention is to provide a sinking and grabbing control method that solves the long problem.

In order to achieve the above object, the bucket gripping control method of the present invention is a gripping control method for a crane with a multi-rope bucket, in which the support motor generates a low torque in the hoisting direction to take up the slack in the support rope. In the gripping control method, which grips the bucket by letting it sink under its own weight while simultaneously winding up the opening/closing rope and closing the bucket, the support motor rotates in the direction in which the support rope is fed out due to the low torque characteristics of the support motor. At this time, the low torque value of the support motor in the winding direction is set to a large value, and as the rotational speed of the support motor in the direction in which the support rope is fed out becomes faster, the low torque of the support motor in the winding direction is increased. When the support motor is rotating in the direction in which the support rope is wound, the low torque value of the support motor in the winding direction is set to a small value, and the support motor is rotated in the direction in which the support motor is wound. It is characterized by having a characteristic that the low torque of the support motor in the winding direction decreases as the rotation speed of the support motor increases.

As a result, when the support rope is moving in the unwinding direction contrary to the torque generation direction of the support motor, the torque generated by the support motor in the winding direction is increased, and as the unwinding speed of the support rope becomes faster, the support motor Increase the generated torque in the winding direction. This exerts a resistance against the force that causes the bucket to stall or overturn, or the force that attempts to continue rotating due to the inertia of the rotating parts of the motor and brake, and prevents the bucket from stalling or overturning. To prevent the support rope from becoming too loose by suppressing speed increase in response to a load force that is about to change, making it difficult for the inertia force of a rotating part to be applied, and quickly decelerating the inertia force applied in the direction in which the support rope is fed out.
Further, when the support rope is rotating in the winding direction, the torque of the support motor is reduced to take up only the slack in the support rope, and no force is generated to lift the bucket. Furthermore, by reducing the torque as the winding speed increases, the support motor is prevented from rotating too fast in the winding direction, and when the support rope is stretched, the inertia of the rotating parts of the motor and brake lifts the bucket. Prevent force from occurring.

Furthermore, by memorizing the position of the support rope at the time of the gripping operation and increasing the low torque value of the support motor according to the amount that the support rope has let out from the position at that time, it is possible to avoid stalling. prevent. At this time, when the bucket is lowered by a certain amount from the height at which the gripping operation was performed, the torque of the support motor to lift the bucket balances the load that causes the bucket to fall, and the bucket can be stopped from falling.
In addition, the support rope position at the time when it is detected that the bucket has landed on the floor is memorized, and from the point where the support rope is paid out a certain amount from that position, the torque of the support motor is increased according to the amount that the support rope is paid out. Even when a grasping operation is performed on a slope, the bucket is tilted diagonally during the grasping operation, the tilt of the bucket is corrected at the end of the grasping operation, and the grasping can be completed after taking up the slack that has occurred in the support rope. .

In addition to these support motor torque control methods, in the case of a method that uses a load cell type load meter to detect landing on the floor, when the load cell does not detect landing on the floor, the support motor is not moved and the support brake is closed. By setting the bucket to the state and operating only the opening and closing operations, the bucket is closed rather than grabbed, and functions as a safety device to prevent stalling.

According to the bucket gripping control method of the present invention, it is possible to maintain the performance of sinking gripping control using the low torque of the support motor, which can grip a larger amount, while solving the problems of bucket stalling and overturning, and further reducing the slack of the support rope. It is possible to provide a crane with a multi-rope bucket that is safer, more stable, and easier to use by quickly picking up items and shortening the operation time for grabbing.

FIG. 2 is a plan view of a winding device of a crane that controls a multi-rope bucket. FIG. 2 is a structural explanatory diagram of a multi-rope bucket. FIG. 3 is an explanatory diagram of an opening/closing rope of a multi-rope bucket. It is an explanatory view of sinking grip control by low torque control of a support motor. FIG. 3 is an explanatory diagram of a falling situation when landing on an inclined surface. FIG. 3 is a characteristic diagram of low torque characteristics of a support motor. FIG. 2 is a control block diagram of a speed control system that generates torque characteristics of a support motor. It is a characteristic diagram for changing the amount of torque generated by the support motor with respect to the amount of payout of the support rope.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The bucket gripping control method of the present invention will be described below with reference to the drawings.

FIG. 1 shows a plan view of a crane winding device that operates a multi-rope bucket.
A support motor HM equipped with a speed detector PG is connected to a support drum HD via a brake BR and a speed reducer GR, and a support rope HW is wound around the support drum HD.
A load cell LC is attached to a portion that captures the load applied to the support rope HW (for example, a bearing portion of the support drum HD), and a support position detector HP is attached to the shaft of the support drum.
The opening/closing device also has the same configuration as the support device and is arranged independently, and the opening/closing motor GM with a speed detector PG is connected to the opening/closing drum GD via the brake BR and reducer GR. Rope GW is wrapped around it. A load cell LC and an open/close position detector GP are attached.

FIG. 2 shows the structure of a multi-rope bucket, and FIG. 3 shows the opening/closing rope portion of the multi-rope bucket.
The support rope HW is fixed to the upper sheave box HB and supports the entire bucket. A connecting rod is connected to the upper sheave box by a link structure with a pin, and is connected to the shell CL. The shells are linked by a lower sheave box BB. A claw TA is attached to the tip of the shell.
Here, the opening/closing rope GW is connected multiple times via the sheave SH attached to the lower sheave pin BS in the lower sheave box BB and the sheave SH attached to the upper sheave pin HS in the upper sheave box (four ropes are shown in FIG. 3). The end of the opening/closing rope GW is fixed to the upper sheave pin HS with a cotter sheave CS.

The bucket GB operates in five operations: opening, closing, grasping, hoisting, and lowering by the movement of the support rope and the opening/closing rope.
The opening operation is performed by winding down the opening/closing rope GW while the support rope HW is stopped.
The closing operation is performed by winding up the opening/closing rope GW while the support rope HW is stopped. In the closing operation of stopping this support rope HW and winding up the opening/closing rope, the bucket GB cannot be gripped because the support is holding down, so a grasping (sinking and grasping) operation is required in addition to the closing operation.
The gripping operation maintains a state in which the torque generated by the support motor HM continues to be generated in the winding direction with a weak torque (herein referred to as "low torque") that is enough to wind the support rope HW, The opening/closing rope is hoisted. At this time, the support motor HM moves in the lowering direction under the pulling force due to the weight of the bucket GB, resulting in a sinking and grasping operation in which the bucket GB sinks and closes due to the weight of the bucket GB.
The hoisting operation is performed when the support rope HW and the opening/closing rope GW are hoisted simultaneously at a constant speed.
The lowering operation becomes a lowering operation when the support rope HW and the opening/closing rope GW are lowered at the same speed at the same time.

In the structure of the opening/closing rope shown in Fig. 3, when the stroke of the lower sheave box BB while the bucket GB changes from the open end state to the closed end state is 1.25 m, the number of sheaves SH is multiplied by 4. In this case, the length of the open/close rope GW that comes out from inside the bucket while the bucket GB changes from the open end state to the closed end state is 5 m (1.25 m x 4 ropes).
When the shells of the bucket GB are restrained with each other in the closed end state, the opening/closing operation in the closing direction becomes locked, and the opening/closing rope GW becomes able to support the weight of the bucket. However, when the bucket GB is not in the closed end state, Even if the opening/closing rope tries to generate force in the hoisting direction, the force of the opening/closing rope will be released as the bucket GB moves in the closing direction, and until the opening/closing rope GW in the 5 m bucket is exhausted, the opening/closing rope GW will not be able to I don't have the strength to support GB.
In the structure of this multi-rope type bucket, when the bucket GB is open and the opening/closing rope does not have any tension force, and the support motor HM has a low torque, the gripping operation is such that all the ropes that hang the bucket GB have tension force. However, if you try to grab the bucket while it is suspended in the air, it will stall and fall, and if you try to grab it on a slope, it will fall over.The present invention solves these problems.

A normal gripping operation will be described with reference to FIG. 4 regarding sinking gripping control using low torque control of the support motor.
The support rope HW and the opening/closing rope GW are lowered and moved in the direction DW, and the bucket GB's own weight bites the claw TA onto the bulk cargo HO to stop the bucket GB from landing on the floor. At this time, in the case of manual operation, the operator visually confirms that the support rope HW and opening/closing rope GW have become slack and then turns off the lowering controller, so normally the operation is as shown in (1) in Figure 4. , the landing stops with the support rope HW and opening/closing rope GW greatly slackened.
Subsequently, when the sinking operation is performed, as shown in (2) in Fig. 4, the opening/closing rope GW winds up at high speed, and the support rope HW slowly winds up at the low torque winding LU state when it stops landing on the floor. Take up the slack.
When the opening/closing rope GW is further wound up, the bucket closes as shown in (3) of FIG. 4 from the time when the slack in the opening/closing rope GW is taken up. Then, as the bucket closes, the entire bucket falls under its own weight.
As the gripping operation time further elapses, as shown in (4) in Figure 4, the slack in the support is taken up by the low-torque winding of the support, and the support rope HW is pulled by the weight of the bucket to the extent that the bucket sinks under its own weight. As a result, the support rope HW enters the low torque delivery state LD. At this time, the support motor HM continues to be in a low torque hoisting state.
Subsequently, the closed end state of state (6) is reached through (5) in Fig. 4, but when the closed end is reached and the closing operation is mechanically restricted, a force is generated in the opening/closing rope GW to lift the bucket GB. , the opening/closing rope GW lifts the bucket GB. On the contrary, slack occurs in the support rope HW, and the low torque of the support motor HM winds up this slack to complete the grasping.
A series of complex movements from (1) to (6) in Figure 4 can be performed by simply issuing a low-torque hoisting command to the support motor HM and a hoisting command to the opening/closing motor. The advantage of sinking grip control using low support torque is that it allows for gripping operations.

However, when performing sinking and grabbing control using low support torque, if the conventional low torque method simply lowers the torque of the support motor, the bucket will stall and fall if it is suspended in the air, and if it lands on a slope, as shown in Figure 5. The bucket GB falls over. This is because the support rope HW has low torque and no tension, and the opening/closing rope GW contained in the bucket GB is let out (5 m in this embodiment) and has no tension.

Therefore, the torque characteristic diagram of the support motor HM is shown in FIG. 6, which solves the problem of stalling and falling of the bucket GB and overturning while making use of the advantage of sinking and grasping control using low support torque.
In the characteristic diagram of Fig. 6, the horizontal axis is the rotational speed of the support motor HM, expressed as a percentage of the rated rotational speed, and the positive side with the zero point as the border is the support rope in the same direction as the direction in which the support motor HM is emitting torque T. On the side of the HW that performs low torque winding LU, the negative side is in the opposite direction to the direction in which the support motor HM is emitting torque T, and the motor torque is overcome by the bucket's own weight and is operating in the low torque unwinding LD side. Show that.
The vertical axis indicates the percentage of the torque generated by the support motor HM relative to the rated torque, with the positive side indicating the magnitude of the torque occurring in the winding direction, and the negative side indicating the magnitude of the torque occurring in the winding direction. Show that.

The curve of H<1.2m drawn by the solid line in FIG. 6 is the initial characteristic of the torque of the support motor when a gripping operation is performed. H is the amount that the support rope has let out from the point where the grip started (the amount that the bucket GB has sunk), and when the value of the amount H that the support rope has let out is 1.2 m or more, it moves linearly in the direction of the dotted curve. Increase torque.
At this time, the amount H that the support rope has let out is determined by the position at which the reading value of the support position detector HP is higher, either at the moment when the load cell LC detects landing on the floor or at the moment when the controller etc. performs a gripping operation. The value obtained by subtracting the current detection value of the support position detector HP from this stored value is set as the value of the amount H by which the support rope is let out.

Here, the point at which the torque T of the support motor HM is increased is the point where the amount H that the support rope has let out is 1.2 m or more, because the amount of sinking of the bucket GB when performing normal sinking grip is less than 1.2 m, so it is set to 1.2 m. In other words, if it exceeds 1.2m, it is an abnormal condition, either when a sinking grab operation is performed while suspended in the air, or when a sinking grip is performed on a slope and the bucket GB is about to fall. The low torque of the support motor HM is increased in accordance with the amount H that is fed out, thereby exhibiting the effect of stopping the motion of stalling and falling or overturning.

Here, it is necessary to change the set value of the amount H of the support rope, which is 1.2 m, depending on the size of the bucket and the type of the object to be grabbed. For example, if the size of the bucket is large, the value is greater than 1.2m, and if the bucket is small, the value is less than 1.2m, and if the object to be grasped is a loose load HO (wood chips, etc.). The value is greater than 1.2 m for items with large sinking (such as clay, sludge, combustible garbage, etc.), and 1 for items with small sinking due to dense bulk cargo (such as clay and ore). .Set smaller than the value of 2m.

The solid line curve in Fig. 6 shows that when the speed ω goes to the negative side (low torque delivery side), the amount of torque T generated increases, and as the speed ω goes to the negative side (low torque delivery side) faster, the amount of torque T generated increases. It is set so that the amount of torque T generated is large.
This has the effect of keeping the speed low when the bucket is about to stall or tip over, and even if you make a mistake in operating the bucket while it is hanging in the air and grab a sinking grip, the bucket will not tip over on a slope. Even when the controller is stopped, there is enough time to return it to its original stop position.

When the support motor is in a low torque state during sinking and grabbing, when the bucket sinks greatly and the support rope HW is pulled by the bucket and moved at high speed in the feeding direction, the rotating parts such as the support motor and brake may be affected by a large amount of force. Inertial force is generated. At this time, if the low torque of the support motor HM is a conventional simple small torque, the power to stop the inertia once attached to the rotating part is weak, and it takes time to decelerate the rotation, and during that time, the support rope HW is unwound. I kept going and it took extra time to pick up the slack. In the present invention, as shown in Fig. 6, the speed ω has a characteristic that increases the torque on the negative side (low torque delivery side), so it suppresses the phenomenon of excessive support rope HW coming out and shortens the slack removal time. are doing.

As shown in Fig. 6, when the speed ω is high on the negative side, a torque T large enough to support the bucket GB is generated, but when the speed on the negative side of the speed ω becomes close to zero speed, the torque T becomes small. The weight of the bucket GB is applied to the bulk cargo HO, and the bucket GB sinks at a low speed while the claws TA dig in firmly, so that the amount of grasping can be secured. Furthermore, when the speed ω becomes the plus side (winding side), the torque T becomes even smaller, and since the torque T at this time is only enough to wind up the support rope, the bucket GB will not be lifted up.

When the speed ω increases to the positive side (winding side), the torque T becomes zero at a low speed and becomes a negative torque beyond that. As a result, the speed ω on the winding side is limited to a low speed.
If the winding speed becomes too fast, the inertia of rotating parts such as the support motor HM and brake BR will increase, and when the support rope HW is loosened and tightened, this inertia in the winding direction will cause the bucket to Lifting up the GB reduces the amount of grip. In order to prevent this, the characteristics shown in FIG. 6 are adopted so that the speed does not increase when the slack of the support rope HW is taken up.

When the bucket is open and suspended, the position of the support position detector HP is memorized at the moment the controller is grasped, and the position of the support position detector HP is memorized from the memorized value in order to prevent stalling if the controller is grabbed by mistake. The value obtained by successively subtracting the current detected value of HP is successively updated as the amount H that the support rope has let out. Since the bucket is being grabbed while suspended in the air, there is no pressure on either the support rope HW or the opening/closing rope GW, so the situation is about to stall and fall. As the speed of the rope HW is increased in the payout direction, the torque T of the support motor HM is increased, so an increase in the falling speed of the bucket GB is suppressed and the speed is stabilized. When the support rope HW has let out 1.2m, the torque of the support motor HM begins to increase and the falling speed begins to slow down, and when the support rope HW has fallen about 2m, the torque of the support motor HM and the force pulling the bucket due to gravity are balanced. The bucket stops falling.

When the bucket is lowered onto a slope and lands on the slope, a landing signal is input from the load cell LC, and the position of the support position detector HP at that moment is memorized. Then, a lowering stop operation is performed, and the support rope HW and opening/closing rope GW are loosened and decelerated to a stop in the state GBB when the bucket lands on the ground in FIG.
With the conventional low torque characteristics, if you start the gripping operation in the state of GBB when the bucket lands on the ground in Figure 5, as the shell CL of the bucket GB closes, the bucket shape will lose its stability, and the support rope HW and opening/closing rope GW will become unstable. The bucket GB was falling over because there was no force to hold it down.

In the present invention, when grasping is started in this state, the bucket GB slowly overturns while being suppressed from increasing the speed of the support rope HW due to the characteristics shown by the solid line in FIG. Then, the value obtained by subtracting the support position detector HP from the position of the support position detector HP memorized at the time of landing is defined as the amount H that the support rope has let out, and the value of the amount H that the support rope has let out is 1.2 m or more. As the torque of the support motor HM increases, the torque of the support motor HM increases as the torque of the support motor HM increases due to the overturning of the bucket GB. The tilting stops when the torque and the falling force that causes the bucket GB to fall are balanced, and the bucket GB can be held on and grabbed at an angle in the state of GBA after the bucket has slipped down as shown in Fig. 5 .
Here, in the read value of the support position detector HP, the position where the person landed is higher than the position where the gripping operation was started, so the position where the gripping operation was started is ignored, and the support position from the position where the gripping operation started is ignored. The characteristics shown in FIG. 6 are calculated based on the value of the amount H that the rope has let out.

In this way, if you hold on to the bucket falling on the slope without placing a grip on it, the shells CL of the bucket GB restrain each other near the closed end, and the opening/closing rope causes the bucket to fall as a strain is exerted on the opening/closing rope GW. . Conversely, the support rope becomes slack. At the same time, the value of the amount H that the support rope has been paid out also decreases, so the torque generated by the support motor HM returns to the small torque that is enough to wind up the support rope HW, so the slack in the support rope HW is taken up. It is possible to remove slack with just a small amount of torque.
At this time, if the support rope HW lifts the bucket GB while the opening/closing rope GW is stopped, the bucket will move in the opening direction due to the correlation between the supporting rope HW and the opening/closing rope GW, and the loose object grabbed. Since the cargo HO will overflow, it is important that the torque of the support motor HM returns to a small torque sufficient to wind up the support rope HW at the end of gripping.

A control block diagram of a speed control system for realizing the characteristics shown in FIG. 6 is shown in FIG. In this control block diagram, as the speed target value ω ^* , the value of ω when the torque T in FIG. 6 is zero is output. Then, the value of the actually output speed ω detected by the speed detector PG is subtracted from the speed target value ω ^* , and the value is calculated by the automatic speed setter ASR using the slope of the proportional characteristic PC of the slope of the graph in FIG. , a torque target value T ^* is generated via a limiter LM.

The change in torque T with respect to the value of the amount H that the support rope has let out can be determined by changing the speed target value ω ^* with respect to the value of the amount H that the support rope has let out as shown in FIG. When the amount H of the rope has reached 1.2 m or more, the torque T increases and can be linearly changed in the direction of the dotted curve.

So far, we have described a method using the support position detector HP as a method for detecting the amount H that the support rope has let out, but in many cases a pulse encoder is used for the speed detector PG, and the support motor It is also possible to calculate the amount H that the support rope has let out by counting the pulses of the speed detector PG attached to the HM, and the support position detector HP can also be omitted.

In addition, as a method of detecting landing on the floor, the method described is to detect when the load on the bucket GB disappears based on the load detection value of the load cell LC, but the control device of the support motor HM outputs a large negative torque when lowering the bucket. There is a method to recognize the landing by detecting the point where the support motor HM torque changes from the state (regenerative torque state) to near zero, and a method to recognize the point where the support motor HM torque changes from the regenerative power state to near zero by looking at the power of the support motor. There are ways to recognize it as a floor, and it is also possible to omit the installation of a load cell LC.

Here, if the load of the bucket GB is detected by the load detection value of the load cell LC, the bucket is suspended in the air, so the support motor HM is stopped and the support brake BR is not released without accepting the sinking and grabbing operation. By providing an interlock as shown in the figure, a method is adopted in which only the opening/closing motor is moved, and the bucket GB can be prevented from stalling and falling, and the bucket can be closed while suspended in the air.
However, if the landing is detected using motor torque or electric power, or if the load cell LC is incorrectly calibrated or malfunctions, the interlock for reliable sink grip cannot be established, so the support motor HM will move in the unwinding direction. In this case, a method of increasing the torque of the support motor or a method of restoring the torque T of the support motor HM by the amount H that the support rope is let out from the position where the sinking and grasping operation was performed are effective.

The bucket grasping control method of the present invention has been described above based on the embodiments thereof, but the present invention is not limited to the configuration described in the above embodiments, and may be modified as appropriate without departing from the spirit thereof. can be changed.

The bucket gripping control method of the present invention utilizes the advantage of submerged gripping control with low torque of the support motor, which can store many loose objects in the bucket and secure a large amount of grasping, while reducing the torque of the support motor to a low torque. A crane with a multi-rope bucket that is safe and easy to operate solves the problems that occur when the bucket stalls and falls, the bucket overturns, and the support rope is fed out more than necessary and takes time to take up the slack. It can be suitably used.

CR Crane HD Support drum GD Opening/closing drum HM Support motor GM Opening/closing motor BR Brake GR Reducer LC Load cell HP Support position detector GP Opening/closing position detector PG Speed detector HW Support rope GW Opening/closing rope GB Bucket HB Upper sheave box LL Connecting rod CL Shell TA Claw BB Lower sheave box HS Upper sheave pin BS Lower sheave pin SH Opening/closing sheave CS Cotter sheave HO Bulk cargo DW Lowering (feeding out)
UP Winding (winding)
LU Low torque winding LD Low torque payout PT Pit GBB When the bucket lands on the ground GBA After the bucket slips down H Amount the support rope pays out ω Speed ω ^* Speed target value T Torque T ^* Torque target value ASR Automatic speed setting device PC Proportional characteristics LM limiter

Claims (4)

There is a gripping control method for a crane with a multi-rope bucket, in which the support motor generates low torque in the hoisting direction to take up the slack in the support rope and sink the bucket under its own weight, and at the same time winds up the opening/closing rope to close the bucket. In the grasping control method that grasps by
As a low torque characteristic of the support motor,
When the support motor is rotating in the direction in which the support rope is paid out, the low torque value in the winding direction of the support motor is set to a large value, and as the rotational speed of the support motor in the direction in which the support rope is paid out increases, the It has the characteristic of increasing the low torque in the winding direction of the motor,
When the support motor is rotating in the direction in which the support rope is wound, the low torque value in the winding direction of the support motor is set to a small value, and the rotational speed of the support motor in the direction in which the support motor is wound is set to a small value. A bucket gripping control method characterized by having a characteristic of reducing the low torque of a support motor in the winding direction as the speed increases. Claim 1 characterized in that when the support rope is let out by a certain amount from the position of the support rope when the gripping operation is performed, the low torque value of the support motor is increased in accordance with the amount that the support rope is let out. Bucket grasping control method described in . Claim characterized in that when the support rope is paid out a certain amount from the position of the support rope when the bucket landed on the floor, the low torque value of the support motor is increased in accordance with the amount that the support rope is paid out. 1. The bucket gripping control method according to 1. 2. The bucket gripping control method according to claim 1, further comprising not accepting a gripping operation when a load cell detects that the bucket has not landed on the floor.

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