JPH0419135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lifting electromagnet device for attracting and transporting loads such as steel materials using electromagnets.

[Conventional technology]

A lifting electromagnet device (hereinafter referred to as a lifting magnet device) is equipped with a plurality of electromagnets (hereinafter referred to as magnets), and the number of magnets to be excited is changed depending on the amount of steel material to be attracted and transported.

By the way, in the lifting magnet device,
It is necessary to control the attraction force (magnetic force) of each magnet in the same way, and for this reason, generally, the excitation current flowing through each magnet is controlled in the same way.

In conventional lifting magnet devices, a power supply device equipped with a constant current control means is provided for each magnet (or so-called selective excitation section), and the excitation current flowing through each magnet is controlled equally (for example, Publication No. 49-15745, Publication No. 57-4052
(Japanese Patent Publication No. 59-24714).

In the case of the above-mentioned lifting magnet device, in order to control the excitation of multiple magnets, multiple power supplies are required. We have proposed a lifting magnet device that can selectively excite multiple magnets using a single power supply.

[Problem that the invention seeks to solve]

By the way, if n is the number of magnets, R is the internal resistance of the lifting magnet, and the control range of the excitation current is Im (maximum) to In (minimum), the output voltage E of the thyristor rectifier depends on the selection of the lifting magnet. The number n (n is a positive integer) is indicated by the number (1).

E=Im・R・n〜In・R・n ……(1) On the other hand, there are various sizes of steel materials to be lifted and transported by a lifting magnet device, and generally,
The excitation current control range required to control the magnetic force of the magnet is about 100 to 10%. Therefore, the actual output voltage of the thyristor rectifier falls within the range shown by equation (2).

E=Im・R・n (maximum) ~ Im/10R (minimum) ……(2) (However, the minimum is when the number of magnets selected is n=1.) In addition, in general, the output voltage control range of a thyristor rectifier is Since it is from 100 to 5%, it is necessary to satisfy the relationship shown in equation (3).

As shown in equation (3), it is necessary that n≦2. In other words, in the case of the "Lifting Electromagnet Device" filed on the same day, the number of lifting magnets is limited to two in order to achieve the above-mentioned necessary excitation current control range; for example, four to eight lifting magnets are required. The above-mentioned required excitation current control range cannot be applied to a lifting magnet device equipped with a lifting magnet.

[Means for solving problems]

In the present invention, a plurality of magnets are connected in series with each other and connected to one voltage-controlled power supply device, and has a selection means for selecting excitation for the plurality of magnets, and also has selection means for selecting excitation for the plurality of magnets, as well as selection means for selecting the excitation current to be passed through the magnets and the excitation current for the magnets. Determine the required power supply voltage based on the resistance and the selected number of magnets,
A lifting magnet device is obtained which includes a control means for controlling the output voltage of the voltage controlled power supply device by comparing the required power supply voltage with a predetermined reference voltage.

〔Example〕

The present invention will be explained below with reference to Examples.

First, referring to FIG. 1, an AC power source (not shown) is connected to a thyristor rectifier 2 via a power transformer 1. As shown in FIG. On the other hand, multiple magnets 3
1 to 3n are connected in series with each other and connected to the thyristor rectifier 2. Multiple electromagnetic contactors 4
1 to 4n are connected in series and connected in parallel to the series connected magnets 31 to 3n. As shown in the figure, the connection points between the electromagnetic contactors and the connection points between the magnets are connected.

When lifting and transporting steel materials with the magnet device having the above-described structure, alternating current from the power transformer 1 is converted to direct current by the thyristor rectifier 2, and is supplied to the magnets 31 to 3n as excitation current. On this occasion,
Depending on the amount of steel material to be transported, each magnet 3
Magnetic contactors 41 to 4 arranged in parallel to 1 to 3n
The magnets 31 to 31 to be energized by controlling the opening and closing of n
3n is selectively controlled. For example, magnet 31,
32 and 34 (magnet 34 is not shown in FIG. 1), the contacts of electromagnetic contactors 41, 42, and 44 (magnetic contactor 44 is not shown in FIG. 1) are opened, and the other contacts are opened. Electromagnetic contactor 43, 45-4
The n contacts are closed. That is, the electromagnetic contactor 43,
When the contacts 45-4n are closed, the corresponding magnets 33, 35-3n are substantially short-circuited, and the exciting current is passed through the magnets 33, 35-3n.
There is almost no flow to n, and the electromagnetic contactors 43, 45 to 4
flows through n. That is, magnets 33, 35
~3n is not excited.

Next, the thyristor rectifier 2 is turned on based on a current command from a command circuit (not shown), and the excitation current specified by the current command flows through the magnet. At this time, as mentioned above, the magnets 31, 3
Since magnets 2 and 34 are connected in series, the excitation currents flowing through each magnet 31, 32, and 34 have the same value.

On the other hand, the secondary side of the power transformer 1 is an electromagnetic contactor 5.
The electromagnetic contactor 6 is connected to the thyristor rectifier 2 through a contact 5a thereof, and a predetermined tap is connected to the thyristor rectifier 2 through a contact 6a of an electromagnetic contactor 6. The lifting magnet device also includes a control device consisting of an arithmetic circuit 7 and a comparison circuit 8, and the comparison circuit 8 includes a comparator 8a, a switching transistor 8b, and an electromagnetic contactor 9.

The arithmetic circuit 7 is inputted with the excitation current value to be passed through the magnet (current command i from the command circuit), the resistance value R of the magnet, and the number n of magnets to be selectively excited, and the arithmetic circuit 7 calculates the value of the equation (4). Find the required power supply voltage V shown by

V=i×R×n (4) This calculated required power supply voltage V is input to the comparator 8a. On the other hand, the power supply switching reference voltage v
is input. When the calculated power supply voltage V≧power supply switching reference voltage v, the comparator 8a sends out a high level signal (H signal), and this H signal turns on the switching transistor 8b. By turning on the switching transistor 8b, the electromagnetic contactor 9
is excited, and its contact 9a switches to the terminal 9b side. This excites the electromagnetic contactor 5,
The contact 5a is closed (the contact 6a of the electromagnetic contactor 6 is open).

On the other hand, when V<v, the comparator 8a sends out a low level signal (L signal). As a result, switching transistor 8b is turned off. By turning off the switching transistor 8b, the excitation of the electromagnetic contactor 9 is stopped (that is, it becomes a non-excited state),
This switches the contact 9a to the terminal 9c side. As a result, the electromagnetic contactor 5 becomes de-energized, and the contact 5a is opened. Further, the electromagnetic contactor 6 is excited and the contact 6a is closed.

By the way, when selecting the tap on the secondary side of the power transformer 1, for example, when the electromagnetic contactor 5 operates, the output voltage range of the thyristor rectifier 2 becomes 100 to 5%, and when the electromagnetic contactor 6 operates, the output voltage range of the thyristor rectifier 2 becomes 100% to 5%. This is done so that the output voltage range is 5-0.25%. Therefore, the control range of the output voltage of the thyristor rectifier 2 is 100% to 0.25%. That is, the control range of the output voltage of the thyristor rectifier becomes wider, and as a result, it becomes possible to increase the number of magnets.

In addition, in the above-mentioned embodiment, 2 of the power transformer 1
Although the case in which one tap is provided on the next side has been described, a similar configuration can be made in the case where a plurality of taps are provided.

In addition, in order to reduce the number of electromagnetic contactors, for example, as shown in FIG.
The electromagnetic contactor 41 should be made to correspond to the magnets 1 and 32, the electromagnetic contactor 42 should be made to correspond to the magnets 33 to 35, and the electromagnetic contactor 43 should be made to correspond to the magnets 36 and 37. In other words, one electromagnetic contactor may be arranged in correspondence with a plurality of magnets. moreover,
As shown in FIG. 3, magnets 31 and 32 that are constantly excited are provided, and an electromagnetic contactor 41 is provided for the magnet 33, an electromagnetic contactor 42 is provided for the magnets 34 and 35, and an electromagnetic contactor is provided for the magnets 36 and 37. The electromagnetic contactor 43 may be made to correspond.
That is, a magnet that is constantly excited may be provided, and one electromagnetic contactor may be provided corresponding to one or more magnets. As described above, various arrangement relationships between the magnet and the electromagnetic contactor can be considered.

〔Effect of the invention〕

As explained above, according to the lifting magnet device according to the present invention, it is possible not only to control the current flowing through a plurality of magnets in the same way with one voltage-controlled power supply device, but also to control the output voltage of the voltage-controlled power supply device. The range becomes wider, and as a result, there is an effect that the number of magnets can be increased.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of a lifting magnet device according to the present invention, and FIGS. 2 and 3 are diagrams showing other examples of the connection relationship between a magnet and an electromagnetic contactor, respectively. 1...Power transformer, 2...Thyristor rectifier, 31-3n...Magnet, 41-4n...
Electromagnetic contactor, 5, 6...Magnetic contactor, 7...Arithmetic circuit, 8...Comparison circuit.

Claims (1)

[Claims] 1. In a lifting electromagnet device that includes a plurality of electromagnets and uses the electromagnets to attract and transport cargo, the plurality of electromagnets are connected to each other in series and connected to one power supply device, and the plurality of electromagnets a selection means for selecting an electromagnet to be excited from among the electromagnets, and determines the required power supply voltage based on the excitation current to be passed through the electromagnet, the resistance of the electromagnet, and the number of electromagnets, and determines the required power supply voltage and the predetermined voltage. A lifting electromagnet device comprising: control means for controlling the output voltage of the power supply device by comparing the output voltage with a reference voltage determined by the power supply device.