JPS62167193A - Method of detecting hung load of 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] Industrial Field of Application The present invention is directed to lifting and transporting steel plates, etc., one by one using a lifting magnet (hereinafter simply referred to as rifmag under 321). Concerning how to detect.

BACKGROUND OF THE INVENTION Conventionally, in this type of detection method, a combination of a hanging load detection rod and a limit switch is attached to a rifmag, and it is mechanically detected whether or not a suspended load is attracted to the rifmag.

Fig. 6 shows a conventional example of such a mechanical detection method, in which a riffmag (1) is suspended from a winding drum (3) by a winding (lowering) wire (5). It is suspended from a suspension beam (4) by a plurality of wires (7), and the suspension beam (4) is hoisted up while the rifmag is energized, and the topmost one of the stacked steel plates αQ is lifted up. When the riffmag (1) adsorbs the steel plate αQ, the w
The fourth hook αQ pushes up one end of the hanging load detection rod (9) to activate the limit switch (8). The limit switch (8
) is activated, the information is transmitted through the cable (6)
A control circuit is arranged to stop the lowering of the riffmag that is sent to the electrical room (not shown) of the crane (2) and suspended from the lifting beam (4), and in this way the two It is designed to prevent more than one steel plate αO from being adsorbed at the same time.

Purpose of the Invention However, in such a conventional method, the steel plate (1G) is sucked into the rift mag (1) and
When the suspended load detection rod (9) receives a large impact, a mechanism combining the detection rod (9) and a limit switch (8) is activated. However, there was a problem in that the limit switch (8) frequently malfunctioned or misadjusted, making stable detection impossible. In other words, if the above-mentioned suspended load cannot be detected properly, the lowering cannot be stopped, and the rifmag (1) will descend too much, and the unplanned second and subsequent steel plates αQ will also be adsorbed at the same time. There was a problem that transportation work could not be carried out normally due to excessive electrolytic corrosion.

The present invention aims to solve such problems.

Structure of the Invention The present invention has been made to achieve the above-mentioned object, and is an epoch-making method that uses electrical detection in place of the conventional mechanical detection method. A riffmag that attracts steel materials by DC excitation is characterized in that an alternating current magnetic field is superimposed on a direct current magnetic field, a change in magnetic resistance of the alternating current magnetic field is detected, and this detected value is compared with a preset setting value. This is a hanging load detection method.

As a method of superimposing an alternating current magnetic field on a direct current magnetic field, there is a method in which alternating current is superimposed on the supplied direct current in advance and power is supplied to the riffmag, and an attraction coil that is excited by a direct current is placed inside the rifmag main body, and an attraction coil is excited by an alternating current. There is a method of arranging the hanging load detection coil in parallel.

More specifically, when the 220V DC power supply that supplies power to the RiffMag is superimposed with an alternating current of about 5% to 10% voltage to the RiffMag coil, the DC component acts as an electromagnet to attract the steel plate to the RiffMag. , the alternating current component operates as described below. In other words, the magnetic permeability of a steel plate is 500 to 1000 times higher than that in air, so when a steel plate is attracted to the RiffMag, the magnetic resistance decreases compared to when the steel plate is not attracted. The alternating current flowing through the device is significantly reduced. This phenomenon is used to detect that a steel plate has been attracted to a riffmag, and the current flowing through the @electrical path by an AC shunt installed in the electrical path between the riffmag power source and the riffmag coil. The alternating current component is separated and converted to direct current using a rectifier circuit. This converted value is compared with a preset value, and when the value is smaller than the set value, the plate is attracted to the riffmag. This is a detection method that determines that

When installing a DC coil and an AC coil in parallel, in the same way as the above method, use a steel plate detection coil that is supplied with an AC power source of ACIOV to 100 V in parallel with a steel plate adsorption coil that is supplied with a 1σ current power source of 220 V DC. A coil is installed inside the riffmag body. The adsorption detection of the steel plate can be performed in the same manner as described above by detecting the current of the AC power source.

Embodiment A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention, where ■ is a DC WL source for supplying DC current to the riffmag (1), αD is an AC power supply, and a3 is a DC current and an AC current. This is a transformer for superimposing. An AC shunt (CT) installed in the electrical path from the DC power supply (a) and the transformer (to) to the refmag (1) separates only the alternating current component of the current co-supplied to the refmag (1). The current is guided through a rectifying and smoothing circuit α to convert it into direct current, and this output is sent to a comparator αQ.

The rectifying and smoothing circuit I is a rectifier and a reactor.

It consists of a smoothing circuit consisting of a capacitor and a resistor (R). The set voltage VB of the comparator (to) is set by the setting device (
(VR).

FIG. 3 shows the waveform of the current supplied to the riffmag (1), which shows that the alternating current is superimposed on the direct current.

FIG. 4 shows the current waveform on the secondary side of the AC shunt (CT). This is the waveform of an exchange separated by an alternating current shunt (CT).

FIG. 5 shows the output voltage waveform of the α station of the rectifying and smoothing circuit.

In each of FIG. 3, FIG. 4, and FIG. 5, the broken line is the waveform when the steel plate is not attracted to the riff mag, and the solid line is the waveform when the steel plate is attracted to the rif mag.

If the output voltage of the rectifying and smoothing circuit when the steel plate is not attracted to the refmag is V, and the output voltage when the steel plate is attracted to the IJ mag is vt, then V, > VB
It is.

Therefore, the voltage V of the setting device VR is set in advance so that Vl > V
If it is set so that B > vt, when the output voltage is higher than the set voltage Va, that is, when the steel plate is not attracted to the riff mag, the output of the amplifier (AMP) is generated and the relay (R, ) operates, but when the steel plate is attracted to the rifmag, the output voltage becomes lower than the set voltage VB, the output of the amplifier (AMP) becomes QV, and the relay (R, ) becomes inoperative.

Therefore, it is possible to determine whether the relay (Ry) is operating or not and whether or not the riff magnet is attracting a magnetic material such as a steel plate.

FIG. 2 is a circuit diagram showing another embodiment of the present invention,
Inside the refmag (1), there are provided an attraction coil α· to which a DC power source (6) is supplied and a detection coil αη to which an AC power source (11) is supplied. The alternating current flowing through the detection coil α is separated by an AC shunt (CT), and as described above, it is possible to determine whether or not the steel plate is attracted by the rectifying and smoothing circuit α and the comparator αe.

Effects of the Invention As described above, according to the method of the present invention, it is possible to detect the suspended load of a riffmag in a non-contact manner, so there is no risk of the detector malfunctioning or misalignment as in the conventional detection method, and + [8 The reliability of load detection has become extremely high.

As a result, the reliability of automatic operation of steel plate transport cranes, etc. powered by Riff Mag I has been significantly improved.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is a circuit diagram of another embodiment of the present invention, FIGS. 3, 4, and 5 are current and voltage waveforms, and FIG. 6 is a circuit diagram of another embodiment of the present invention. FIG. 2 is a cross-sectional view showing a conventional detection method. 1... Riff mug, 2... Crane, 3... Winding drum, 4... Hanging beam, 5.7... Wire, 6...
・Cable, 8... Limit switch, 9... Hanging load detection rod, 1o... Steel plate, 11... AC power supply, 12.
... DC power supply, 13 ... Transformer, 14 ... Rectification and smoothing circuit, 15 Yui calibration device, 16 ... Adsorption coil, 17.
...Detection coil, CT...AC shunt. Applicant: Sumitomo Metal Industries, Ltd. Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. In a lifting magnet that attracts a steel material with the generated magnetic force by supplying direct current, an alternating current magnetic field is superimposed on the attracting direct current magnetic field, a change in magnetic resistance of the alternating magnetic field is detected, and this detected value is A lifting magnet hanging load detection method characterized by comparing with a preset setting value. 2. Supplying a current obtained by superimposing an alternating current on the direct current that feeds the lifting magnet, and converting the secondary output of an alternating current shunt provided in the electrical path between the lifting magnet and the direct current power source to direct current, The method for detecting a suspended load of a lifting magnet according to claim 1, wherein this converted value is compared with a preset value. 3. An attraction coil excited by a direct current and a suspended load detection coil excited by an alternating current are arranged in parallel in the main body, and the value of the alternating current flowing through the suspended load detection coil is detected. The method for detecting a suspended load of a lifting magnet according to claim 1, wherein the detected current value is compared with a preset value.