JPS58144085A - Method of controlling lifting magnet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to a method for controlling a lifting magnet),
In particular, the present invention relates to a control method for releasing equipment attracted by residual magnetism in a permanent magnet type lifting magnet.

As shown in Fig. 1, a magnetic path is made up of a magnetic steel 1, a yoke 2, an outer pole 3, and an inner pole.A current is passed through a coil 5 wound around the magnetic steel 1 to perform magnetization and demagnetization. When lifting magnets are used, residual magnetism usually remains after demagnetization. Of course, it is desirable that there is no residual magnetism, but in actual work, residual magnetism may remain due to various factors.
It is extremely difficult to completely eliminate this.

This residual magnetism is very small and does not attract the steel material 6 to be attracted, but if there is material such as cut steel material or nails, it may be attracted. Then, if you try to adsorb steel while the equipment is adsorbed to the magnetic pole surface,
Since the equipment is sandwiched between the magnetic pole surface and the steel material, a gap is created there, causing the inconvenience of weakening the adsorption force.

Regarding residual magnetism, magnetic steel is magnetized by being excited by a coil and demagnetized by being reversely excited, but the magnetic force is the permeance of the magnetic circuit (ease of magnetic flux 1) even when the same current is passed through it. I) It changes.

The main factors are (1) the size and thickness of the steel material, (
2) The size of the gear on the suction surface, warpage or distortion of the steel material, presence of scale and dust), etc., and these things change in various ways in actual work. Therefore, the magnetic force also fluctuates every time a steel material is attracted, so even if the excitation is overexcited with a current of a magnitude corresponding to the current, the magnetic force cannot be completely erased, and residual magnetism remains. It turns out. Furthermore, depending on the size of the reverse excitation heavy ring relative to the magnetic force, the polarity of the residual magnetism may be N polarity or S polarity.

The present invention was developed in view of the above points, and before adsorbing steel materials, demagnetization is performed by passing a small current with a slow rise in both the forward and reverse directions in the air, and the material is released and dropped. When suctioning, make sure that no equipment is attached to the magnetic pole surface. This eliminates the low adsorption force due to gears and pulls caused by intervening equipment (and improves safety through reliable suction and improves work efficiency. The purpose is to improve efficiency.The following will explain the embodiments shown in the drawings.

In FIG. 2, 7 is a permanent magnet type lifting magnet body, and 8 is a power supply device, which is usually a thyristor-controlled power supply. Reference numeral 9 denotes a controller that gives a command signal to the power supply device 8, and each device is connected by a power supply cable IO. The configuration of these devices is the same as that of the conventional type, but in the present invention, the I device 8 has the function of obtaining the necessary current output to achieve magnetization, demagnetization, and air demagnetization, respectively.

Therefore, first, before adsorbing a steel material, that is, when the lifting magnet is in the air in an unloaded state, when the controller 9 gives air demagnetization commands in the forward and reverse directions to the power supply device 8, the power supply device 8 outputs a small current with a slow rise as shown in FIG. 3 to the lifting magnet 7 in response to the air demagnetization command. When the polarity of the demagnetizing field caused by this demagnetizing current and the residual magnetism of the magnetic steel is opposite, the magnetic steel passes through a point where the two cancel each other out and the magnetic force becomes zero, so at this point the magnetic steel is attracted to the magnetic pole by the residual magnetism. The equipment falls into the air.

As mentioned above, the polarity of residual magnetism can be on either the N or S side, so it is necessary to perform aerial demagnetization in the positive direction and in the opposite direction. Also, if the power supply rises quickly,
The speed at which the magnetic force passes the zero point becomes v, and the equipment that was moving away at the zero point may be immediately attracted with the opposite polarity as soon as it passes the zero point, so the rising edge of the air demagnetizing current is equal to the rated current. It is necessary to suppress the rise to about 173 to 1/4 or less, and specifically, it is set according to the limit of the size of the equipment that can allow adsorption. Furthermore, if the air degaussing current is large, the residual magnetism will increase, so when the output is cut off, the residual magnetism will return to its original size. It should be of a size that does not give permanent magnetizing force to the magnetic steel, and should be about 15 to 20% of the magnetizing current.

Now, after this aerial demagnetization, lifting magnet 7
is placed on the steel material C, and is connected from the controller 9 to the power supply device 8.
A magnetization command is given to the magnet, and the power supply device 8 applies a current output necessary for magnetization to the magnet. With this 1) ill material 6
is attracted to the lifting magnet 7 and transported to a predetermined position.

The rope material 6 transported to a predetermined position is placed on the floor, and then a demagnetization command is given from the controller 9 to the power supply device 8, and the power supply device 8 applies the current output 4 necessary for demagnetization to the magnet. As a result, the lifting magnet 7 is made of steel material 6
This will relieve the adsorption of

In this case, since the magnet is demagnetized on the steel material, it is affected by the above-mentioned magnetic force fluctuation factors, and residual magnetism that varies in size depending on the work remains.

Therefore, before starting the next adsorption operation, an air demagnetization current is outputted to the magnet 9 again, and in this way air demagnetization - magnetization -
Demagnetization control is repeated.

In addition, the aerial degaussing command is for example when hoisting a crane, traversing,
If you link it to driving etc. and give it automatically,
At the same time, reliability is increased by ensuring that the work is done every time,
In addition, the driver's operations can be reduced.

As stated above (according to the present invention, the material attracted to the magnetic pole surface by residual magnetism is removed by demagnetizing it in the air before adhering to the steel material), safety is improved through reliable attraction. 1, it has become possible to improve work efficiency.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the structure of a permanent magnet type lifting magnet, Fig. 2 is a schematic diagram showing the relationship between the lifting magnet, power supply device, and controller, and Fig. 3 is a diagram showing the relationship between the command signal and excitation current according to the present invention. Explanatory diagram. l...magnetic steel, 2...yoke, 3...outer pole, 4...
- Inner pole 5... Coil, 6... Steel material 7... Lifting magnet body 8... Electric 1liii device, 9... Controller. Figure 3 appears after Figure 1.

Claims (1)

[Claims] In a permanent magnet type lifting magnet that performs magnetization and demagnetization using a coil wound around the tapped steel, a small current is passed in the air with slow rises in both the forward and reverse directions before the steel material is attracted. A method for controlling a lifting magnet, characterized in that the lifting magnet is demagnetized and the equipment is released.