JPH03143A - Removing device for ferromagnetic metallic piece - Google Patents

Abstract

PURPOSE:To automatically remove metallic pieces even when these are continuously mixed by providing both a signal generating means for generating a signal according to the movement of a conveyor and an exciting timing carculating means for deciding the exciting timimg of an electromagnet on the basis of this signal. CONSTITUTION:A feebly magnetic raw material 20 is carried by a conveyor 18 and also existence of a ferromagnetic metallic piece mixed into the feebly magnetic raw material 20 is detected by a detector 12 of metal and a detection signal of metal is output. Further the ferromagnetic metallic piece is excited according to the detection signal of metal and an electromagnet 14 attracts the ferromagnetic metallic piece. Excitation is removed in a discharge position 14' and this ferromagnetic metallic piece is released. Furthermore the electromagnet 14 is moved to the discharge position 14' from the attraction position by a transferring means 16. A signal is generated according to movement of the conveyor 18 in a signal generating means 50. Further the exciting timing of the electromagnet 14 is decided on the basis of this signal in an exciting timing calculating means 56. As a result, the metallic piece is automatically removed even when it is continuously mixed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ferromagnetic metal piece removal device for removing ferromagnetic metal pieces mixed into weakly magnetic raw materials such as iron ore and sintered ore.

[Conventional technology]

For example, in a blast furnace, iron ore as a raw material is transported to a number of conveying devices arranged in tandem and then charged into the blast furnace. If metal pieces such as iron pieces are mixed into the raw material, it will damage the conveyor and cause a supply stop, so it is necessary to remove it as close to the capacity of the conveyor as possible.

Devices that automatically remove metal pieces generally use electromagnets, but in this case, if the electricity is constantly on, even weakly magnetic iron ore will be attracted, reducing the suction force. It is important to apply electricity only during the transit period.

FIG. 3 is a diagram showing an example of a metal piece removing device using an electromagnet. Column (a) is a view of the device viewed from a direction perpendicular to the feed direction of the raw material. A metal detector 12 is provided in the middle of the conveyor 18 to detect the presence of a ferromagnetic material by a change in magnetic permeability within the coil. Iron ore 20 supplied from hopper 10 is placed on conveyor 18, passes through metal detector 12, passes below electromagnet 14, and is sent to the next conveyor (not shown).

When the presence of a ferromagnetic metal piece is detected by the metal detector 12, the electromagnet 14 is excited by a timer 22 with a delay of a predetermined time, that is, the time from the detection position to the time when the piece reaches below the electromagnet 14. The electromagnet 14 that has attracted the metal piece is moved by the moving device 16 in a direction perpendicular to the conveyance direction.

Column (b) is a diagram of the moving device 16 and the electromagnet 14 viewed from the transport direction. The moving device 16 moves on the traveling rail 22 from above the conveyor 18 to above the hopper 24.

It is moved to 14' and de-energized. The attracted metal pieces are dropped into the hopper 24, and then the electromagnet 1
4 returns to the position above the conveyor 18.

During this time, the conveyor 18 is continuously operated, and after the electromagnet 14 returns to its original position, automatic removal is possible again. However, when the metal detector 12 detects a metal piece when the electromagnet 14 is not above the conveyor 18, the conveyor 18 is temporarily stopped and removed because it cannot be automatically removed.

[Problem to be solved by the invention]

When the conveyor 18 is stopped, it moves a certain distance due to inertia and then stops; however, the distance varies depending on the weight of the transported items on the conveyor and is not constant. Therefore, with the timer control method, it is not possible to appropriately set the excitation position when the conveyor is restarted. Therefore, there is a problem in that removal at this time must be done manually.

A method in which the electromagnet 14 is excited at the same time as the restart is also considered, but this poses a problem in that the attractive force of the electromagnet decreases for the reasons described above.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a ferromagnetic metal piece removal device that can automatically remove metal pieces even if they are continuously mixed in.

[Means to solve the problem]

The present invention has been made in view of this purpose, and its gist is to provide a conveyor for conveying weakly magnetic raw materials, and a metal detection signal that detects the presence of ferromagnetic metal pieces mixed in the weakly magnetic raw materials. an electromagnet that is excited in response to the metal detection signal to attract the ferromagnetic metal piece and is deenergized at a discharge position to release the ferromagnetic metal piece; A ferromagnetic metal piece removing device comprising a moving means for moving from a conveyor to a discharge position, a signal generating means for generating a signal according to the movement of the conveyor, and an excitation for determining an excitation timing of the electromagnet based on the signal. The present invention is characterized by comprising a timing calculation means.

[For production]

For example, if the signal generating means is a pulse transmitter that generates pulses in synchronization with the movement of the conveyor, by counting these pulses, even when the conveyor is stopped, it will be possible to accurately know the stop position. Even in various cases, the excitation timing calculation means can determine appropriate excitation timing.

〔Example〕

FIG. 1 is a diagram showing one embodiment of the present invention.

Components that are the same as those in FIG. 3 are given the same reference numerals and their explanations will be omitted.

The programmable logic controller (PLC) 56 is a microcomputer with a human output interface and input/output drivers that allows a user to input commands and set control sequences within predetermined constraints. The pulse generator 50 generates pulses from a disk that rotates coaxially with the rotation of the rollers supporting the conveyor 18. The output of the pulse transmitter 50 and the metal detector 12 is PL
C56, and its output signal is output to the conveyor drive control device 54, the moving device 16, and the electromagnet 14 as a signal for controlling the conveyor 18, the electromagnet 14, and the moving device 16, respectively. The conveyor drive control device 54 controls the motor 52 in response to control signals from the PLC 56 to start and stop the conveyor 18. The electromagnet 14 is excited and de-energized according to a control signal from the PLC 56, and the moving device 16 is also excited and deenergized according to a control signal from the PLC 56.
The electromagnet 14 is reciprocated between a position above the conveyor 18 and a position above the hopper 24 in response to a signal from the electromagnet 6.

FIG. 2 is a flowchart showing the control of the PLC 56. A plurality of counters are provided in the PLC in order to process a plurality of metal pieces in parallel.

First, these are stopped (step a), and a signal for starting the conveyor 18 is sent out (step b). When a pulse is manually generated from the pulse generator 50 (step C), one of the plurality of counters that is in operation is counted up (step d). When a metal piece detection signal is input from the metal detector 12 (step e), one of the stopped counters is started at the rising edge (step e).
Step f). Next, if any counter is operating (step g), it means that the metal detector 12 and the electromagnet 14
This means that there is a metal piece between the energized position of Then, the conveyor 18 is started (step i). In step i, conveyor 1 is already
4 is activated, there is no change. The same applies to step j. Next, if any one of the plurality of counters exceeds a predetermined value (step k), it means that the metal piece has reached the excitation position, so the counter is stopped.Step 1) Excitation of the electromagnet 14 A series of operations begins (step m).

Metal pieces are automatically removed by repeating steps cm. Note that even when the conveyor 18 is stopped, monitoring of the pulse input is continued, so even if the conveyor 18 moves due to inertia, the excitation timing is determined taking into consideration the distance of movement.

〔Effect of the invention〕

As described above, according to the present invention, metal pieces can be automatically removed without any manual effort.
Labor saving and cost reduction in the process are realized.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the present invention, Figure 2 shows a PLC.
FIG. 3 is a flowchart of the operation of the conventional system. In the figure, 12...Metal detector, 14...Electromagnet, 16
...Movement device, 18...Conveyor, 20.
...Iron ore, 50...Pulse transmitter. FIG. 1 is a diagram showing an embodiment of the present invention.

Claims (1)

[Claims] 1. A conveyor (18) that conveys a weakly magnetic raw material (20), and detects the presence of a ferromagnetic metal piece mixed into the weakly magnetic raw material (20) and outputs a metal detection signal. Metal detector (12
), an electromagnet (14) that is excited in response to the metal detection signal to attract the ferromagnetic metal piece and is deenergized at the ejection position (14') to release the ferromagnetic metal piece; 1
4) from a suction position to a discharge position (14'); and a signal generating means (16) for generating a signal in accordance with the movement of the conveyor (18). 50); and excitation timing calculation means (56) for determining the excitation timing of the electromagnet based on the signal.