JP2533578B2 - Grab bucket hoisting method and apparatus - Google Patents

Description

The present invention relates to a hoisting device for glove buckets,
The present invention relates to a grab bucket equipped with an AC motor.

[Conventional technology]

The grab bucket is suspended by an opening / closing rope for opening / closing the grab and a supporting rope for moving the grab bucket up and down. Further, each of the hoisting devices has a motor for opening and closing the hoisting device for operating the rope for opening and closing and a hoisting device for supporting the rope for operating the supporting rope. 135093 publication).

To explain the procedure for suspending a load with a grab bucket, first, rotate the open / close hoisting device in the forward direction to feed the open / close rope, open the grab bucket, and in this state, open the open / close hoisting device and the supporting hoisting device. Operate and land the grab bucket. Next, the opening / closing hoisting device is rotated in the reverse direction to close the grab bucket, and then the opening / closing hoisting device and the supporting hoisting device are normally rotated at a constant speed to wind up the glove bucket. Next, the two hoisting devices are normally rotated to lower the grab bucket, the opening / closing hoisting device is normally rotated with respect to the supporting hoisting device, the glove bucket is opened, and the load is discharged.

A DC motor is generally used as the motor for the two hoisting devices of the grab bucket. When using an AC motor,
Since the winding speeds of the opening and closing rope and the supporting rope become unbalanced, the grab bucket may open slightly while the grab bucket is being raised. Therefore, the AC motor type is often used when it is acceptable for the load to spill. In order to prevent this, a clutch is provided between the two hoisting devices, and the clutch is engaged when the grab bucket is raised and lowered while the grab bucket is closed.

[Problems to be solved by the invention]

As described above, if the clutch that connects the motor that drives the opening / closing rope and the motor that drives the supporting rope is provided, it is possible to prevent the grab bucket from being opened while the grab bucket is being raised.

However, this one cannot correct the imbalance between the load applied to the opening / closing rope and the load applied to the supporting rope.

For this reason, conventionally, it is necessary to design one rope to support all the loads. Therefore, the capacity of each motor and the rope must have a large diameter. Along with this, the diameter of the rope sheave and the drum diameter of the hoisting device are increased, and the transmission torque of the clutch is also required to be large. Therefore, the conventional one is expensive.

An object of the present invention is to make it possible to reduce the capacity of the motor, the diameter of the rope, etc. when using an AC motor.

[Means for solving problems]

The present invention causes the two AC motors to generate substantially the same low torque at the time of starting the hoisting after the closing of the grab bucket is completed (the total value of the two torques is required to hoist the hoisting load). Less than the torque), then, after a first predetermined time from the start of energization of the two AC motors, the clutch is energized to connect the rotating shafts of the two AC motors, and then the second predetermined value. After a period of time, the secondary resistors of the two AC motors that generate the low torque are short-circuited.

[Action]

At the end of closing the grab bucket, the tension of the supporting rope is almost zero, the supporting rope is slack, and the hoisting load is applied to the opening / closing rope. When the hoisting is started from this state, the grab bucket remains stopped because the opening / closing motor generates less torque than the torque required for hoisting. At this time, since the supporting rope is slack, the load on the supporting motor is small, the supporting motor is activated, and the supporting rope is wound up. For this reason,
The tension of the supporting rope and the tension of the opening / closing rope are almost the same. At this point, the torque of the two motors is smaller than the hoisting load, and therefore the hoisting cannot be performed. After a predetermined time, that is, when the tensions of the two ropes become almost equal, the clutch is engaged, and the two motors are started.
The two ropes are wound at a constant speed. In this state, after the second predetermined time, the secondary resistor for low torque generation is short-circuited,
Accelerate and wind normally.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In Fig. 1, 1M is a supporting rope AC motor (winding motor), 2M is an opening / closing rope AC motor (winding motor), CL is a supporting motor 1M rotating shaft and opening / closing motor.
It is an electromagnetic clutch that connects the 2M rotating shaft. The two motors 1M and 2M have the same capacity.

General secondary resistors 1R2 and 2R2 and low torque resistors 1R1 and 2R1 are connected to the secondary sides of the supporting motor 1M and the opening / closing motor 2M. Secondary contactors 1S1 to 1S6 and 2S1 to 2S6 are provided for controlling the secondary resistors 1R1, 1R2, 2R1 and 2R2, respectively. The torques of the secondary resistors 1R1 and 2R1 are almost the same, and the total value of both torques is greater than the torque required to hoist the hoisting load (the rated weight of the load and the total weight of the grab bucket). small.

1F and 2F are contactors for forward rotation of the motors 1M and 2M, and 1R and 2R are contactors for reverse rotation of the motors 1M and 2M. 3 is a contactor for the clutch CL.

In FIG. 2, 34H is a hoisting controller and 34C is an opening / closing controller. LS is a limit switch that turns off when the bucket closes. ○ indicates an electromagnetic contactor,
Others show the contactor of the contact.

34H2 shows two notches of the hoisting controller. 34C2 shows two notches of the opening / closing controller. Secondary contactor by timer T3
The introduction of 1S2, 2S2 is decided. A circuit similar to the circuit 10 is provided for each of the three notches to six notches, but this point is the same as the conventional one, and is not shown.

The hoisting operation of such a configuration will be described with reference to FIG. Third
In the figure, the motor and the winding drum for the rope are shown as the same.

First, for the grab bucket in the state of FIG. 3 (A),
Put the control lever in the “close” position of the grab bucket to command the glove bucket closing operation. This turns on the opening / closing controller 34C, so contactor 2F
Is turned on, and the contactor for that contact is turned on. Also, since the series circuit of contactors 2F, 1F is configured, contactors 1S1, 2S1
Is thrown in. Therefore, the opening / closing motor 2M starts operation, the opening / closing rope 22 is wound up, and the grab bucket enters the closing operation. The closing operation accelerates as the notch progresses.
When the grab bucket closes, the limit switch LS turns off, so the closing operation stops. Also, the contactors 2S1 to 2S6 return to the initial state. Further, the brake of the opening / closing hoisting device is activated to maintain this state. Even if the limit switch LS is operated, the hoisting device for opening and closing continues to operate due to inertia, so the grab bucket 20 is located above the ground as is well known in the state where the operation is stopped, and the supporting rope 21 The tension is decreasing (Fig. 3 (B)).

Next, the control lever is turned to the "winding" position to instruct the hoisting operation of the grab bucket. This will turn on 34H of the supporting controller, so contactors 1F, 2F
Are sequentially input. Therefore, the timer T1 starts to start. On the other hand, turning on the contactor 1F turns off its b contact.
As a result, the secondary contactors 1S1 and 2S1 are turned off. Therefore, the motors 1M and 2M are started, but the output is low torque.
At this time, the brake of the opening / closing hoisting device is released. For this reason, the supporting motor 1M is
Is wound up and tension is applied to the supporting rope 21 with a low set torque to stop. On the other hand, the opening / closing motor 2M is reversely rotated by a large tension of the opening / closing rope 22 and gives a tension to the opening / closing rope 22 with a low set torque to stop. Therefore, the tension of the supporting rope 21 and the tension of the opening / closing rope 22 are substantially the same. In this way, the low torque is set so that they are almost the same. Since the total value of the torques of the two motors 1M and 2M is smaller than the torque required to hoist the hoisting load, hoisting of the grab bucket does not occur. Further, the low torque is set to such a size that the supporting rope can be wound (FIG. 3 (C)).

Next, when the first predetermined time elapses, the contact of the timer T1 is turned on, so that the clutch contactor 3 is closed and the shafts of the two motors are connected by the clutch CL (FIG. 3 (D)).

When the timer T1 is turned on, the second timer T2 starts counting time, and after the elapse of the second time, the contact of the timer T2 is turned on.
Therefore, the secondary contactors 1S1 and 2S1 are turned on and the hoisting of the grab bucket 20 is started. After that, it accelerates as the notch progresses (FIG. 3 (E)).

The predetermined time of the second timer T2 is set to be larger than the time constant of the clutch CL, and the acceleration is started after the two motors 1M and 2M are completely connected.

In the above embodiment, the timers T1, T2, etc. can be constructed by a microcomputer.

〔The invention's effect〕

As described above, according to the present invention, in the hoisting operation after the completion of the closing operation of the grab bucket, the outputs of the supporting motor and the opening / closing motor are set to low torque, and the tensions of the supporting rope and the opening / closing rope are made substantially the same. Since the two motors are connected to start winding, the capacity of the two motors, the diameter of the rope, the diameter of the sheave, the diameter of the drum, and the capacity of the clutch can be made small and inexpensive. Also,
After connecting the clutch, the secondary resistor for generating low torque is short-circuited, and thereafter, the acceleration winding can be performed as usual.

[Brief description of drawings]

FIG. 1 is a single line connection diagram of one embodiment of the present invention, FIG. 2 is a development connection diagram for hoisting operation of one embodiment of the present invention, and FIGS. 3 (A) to (E) are of the present invention. It is an explanatory view of operation at the time of hoisting operation. 1M …… Supporting AC motor, 2M …… Opening / closing AC motor, 1R
1,1R2,2R1,2R2 …… Secondary resistor, CL …… Clutch, T1, T2
...... Timer, 21 …… Support rope, 22 …… Opening and closing rope

Claims (2)

(57) [Claims] 1. A glove bucket is closed by energizing an open / close AC motor for operating an open / close rope for opening / closing the grab bucket, and the glove bucket is supported during a hoisting operation after completion of the closing operation. The supporting AC motor for supporting the supporting rope and the opening / closing AC motor are energized to have a low torque, both are substantially the same, and the total torque of the two is equal to the hoisting load. Generate a torque smaller than the torque required to climb, and then, after a first predetermined time from the start of energization of the two AC motors, energize the clutch to connect the rotating shafts of the two AC motors, Next, after a second predetermined time, the secondary resistors of the two AC motors that generate the low torque are short-circuited, and the hoisting method of the glove bucket. 2. An opening / closing AC motor for operating an opening / closing rope for opening / closing a grab bucket, a supporting AC motor for operating a supporting rope for supporting the grab bucket, and a rotation of the opening / closing AC motor. A grab bucket hoisting device comprising a clutch connecting a shaft and a rotating shaft of a supporting AC motor, wherein the capacity of the AC motor and the capacity of the supporting AC motor are substantially the same, A normal secondary resistor for acceleration is used for each of the AC motor and the supporting AC motor, the output torque is low, and the total value of the output torques of the two motors hoists the hoisting load. Is provided with a second secondary resistor for generating a torque smaller than the required torque, and a normal secondary second resistor for acceleration is provided in the second secondary resistor, A first means for short-circuiting the first secondary resistor of each of the opening / closing motor and the supporting AC motor in response to a hoisting operation command after the closing operation of the grab bucket by the operation of the motor is provided; The clocking is started by a winding operation command, the clutch is operated after a first predetermined time, and the first secondary of each of the opening / closing AC motor and the supporting AC motor is elapsed by a second predetermined time. A hoisting device for a glove bucket, comprising: a second means for short-circuiting the resistor and the second secondary resistor.