JPS62168566A - Method and device for coating steel plate - Google Patents

Abstract

PURPOSE:To coat both sides simultaneously and uniformly with a simple operation and simple facilities by conveying steel plates by means of a magnetic levitation system and controlling the current of an electromagnet to constantly maintain the levitating position of steel plates. CONSTITUTION:A number of pairs of electric magnets 4 on right and left of the upper part of a coating chamber 1 and a drying chamber 2 are provided longitudinally, and a steel plate P is conveyed by being sucked and levitated and also by magnetizing or demagnetizing the electromagnets 4 by means of sequence control. The front and back side of the steel plate P are coated simultaneously by a pair of coating machines 5 provided upper and lower in the coating chamber 1, dried in the drying chamber 2 and then conveyed out by a roller table 6 for conveying out located higher than a dummy roller 3A. At that time, the distance to the back side of steel plate P is detected by a plurality of laser distance detectors 10 installed between the dummy rollers 3A, based on which the current of electromagnets 4 is controlled to constantly maintain the levitating position of steel plate P.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a coating method and apparatus for painting the front and back surfaces of a steel plate at the same time by sucking and levitating and transporting a steel plate using an electromagnet.

<Prior art and its problems> Heavy steel plates are sometimes treated with a primer (painted) to prevent rust depending on the purpose of use, but conventionally, in both the painting process and the drying process, rollers Because the steel plate is transported on a table, the paint peels off on the back side of the steel plate where it came into contact with the table roller. This disrupts the process and increases the number of man-hours outside of normal work, causing problems.

Therefore, in order to solve this problem, for example, Japanese Patent Laid-Open No. 52-789
As in Publication No. 6B, the steel plate is held upright, and while being transported by a chain conveyor, one side is first painted and dried, and then,
A method has been proposed in which the other side is painted and dried, then the steel plate is returned horizontally and transferred to the next process, but since painting and drying are performed twice, it takes time and requires complicated operations and equipment. There was a problem.

This invention was proposed in view of the above circumstances, and its purpose is to provide a coating method and apparatus that can easily coat both sides of a steel plate simultaneously with relatively simple operations and equipment. It is in.

<Means for Solving the Problems> The coating method according to the present invention attracts and floats a steel plate being conveyed by a large number of electromagnets arranged above the conveyance path, and turns off the excitation of the electromagnets. The front and back surfaces of the steel plate are coated with a coating machine while the steel plate is being conveyed by changing the conveyance path, and the distance to the steel plate is detected using a number of distance detectors installed below the conveyance path. Based on this detection result, the distance to the steel plate is The electric current of the electromagnet is controlled to keep the distance constant, so that both sides of the steel plate can be coated simultaneously without changing the orientation of the steel plate.

The coating apparatus according to the present invention includes: a sealed painting chamber and a drying chamber in which a conveyance path having guide rollers for guiding a side portion of a steel plate extends from the outside to the inside; and above the conveyance path in the longitudinal direction; A plurality of electromagnets are arranged in the width direction and can suction levitate and convey the steel plate; A coating machine is arranged in pairs above and below in the painting chamber and coats the front and back surfaces of the steel plate; A large number of electromagnets are arranged below the conveyance path and are used to coat the steel plate. detect the distance to
It is equipped with a distance detector that outputs the result, and a control mechanism that compares the output signal from this detector with the set value and controls the current of the electromagnet based on this result.The electromagnet attracts and levitates the steel plate and excite the electromagnet. The floating position of the steel plate is maintained constant by controlling the electric current of the electromagnet, and the thickness of the coating film is made uniform.

<Example> The present invention will be described below based on an illustrative example.

As shown in Figure 1, the painting equipment consists of a painting room 1, a drying room 2
A conveyance path 6 passes from the table roller (not shown) in the preheating and cleaning process, which is the previous process, into the chambers 1 and 2.
has been extended.

The conveyance path 6 consists of a dummy roller 3A and a pair of left and right guide rollers 3B that guide the side portions of the steel plate.

On the entrance side of the coating chamber 1 and above the coating chamber 1 and drying chamber 2, a large number of left and right electromagnets 4 are disposed in the longitudinal direction, which attract and levitate the steel plate P and excite or demagnetize the electromagnets by sequence control. Transport by means of transportation.

The steel plate P transported in this manner is coated on both front and back surfaces simultaneously by a pair of coating machines 5 arranged above and below in the coating chamber 1, dried in the drying chamber 2, and then transported to the exit higher than the dummy roller 3A. It is carried out using the installed roller table 6 for carrying out.

The electromagnets 4 have a suction force of 1 ton, for example, and are arranged with dimensions as shown in FIG.
There are 6 pieces in the painting room 1 and about 20 pieces in the drying room 2.

Further, the electromagnet 4 is made variable by appropriate means in accordance with the width of the steel plate P, and for example, the interval 1 is 450 to 450 mm.
It is assumed that it operates within the range of 2250+u. Guide roller 6
B is similarly variable.

Further, as for the iron core used in the electromagnet 4, a super permeable iron core having a large attractive force and a constant magnetic permeability characteristic is used.

Note that the current flowing through the electromagnet 4 is 1 depending on the weight of the steel plate P.
~10 [A] is appropriate. This is a value that the attraction force of the electromagnet 4 is theoretically determined by the relative magnetic permeability of the iron core, the area through which magnetic flux passes, the number of turns of the coil, etc., but when actually attracting it, it is determined by a numerical coefficient than the theoretical value. It is necessary to flow a large amount of current, and experimentally 8 to 12% is appropriate.

Magnetic materials such as iron powder may enter the painting room 1 and drying room 2.
In order to prevent the steel plate P from being attracted by the electromagnet 4 and adhering to the painted steel plate P, the coating chamber 1 and the drying chamber 2 are
is of a sealed type, and furthermore, a Jactof blower 8 and a dust collector 9 are installed on the entrance side of the painting chamber 1 to prevent the intrusion of magnetic dust.

Between the rollers of the dummy roller 3A, a large number of laser distance detectors 10 are installed at intervals in the longitudinal direction to detect the distance to the back surface of the steel plate P, and based on this detection result, the current of the electromagnet 4 is adjusted to the Control is performed as shown in Figure 4 so that the floating position of the steel plate is always constant, thereby ensuring that the coating film thickness is always uniform. Note that the purpose of the drying chamber 2 is to stabilize sheet threading and provide constant drying heat, and the coating chamber 1 does not require detailed control.

The laser distance detector 10 is a commonly used detector that emits a laser beam from a light source to the back surface of a steel plate, receives the reflected light with a receiver, and detects the distance based on the intensity of the light. The accuracy is about 20 to 60 μm.

What is shown in FIG. 4 is a feedback control mechanism for keeping the distance constant. Before threading, a setting signal So corresponding to the reference floating position of the steel plate is sent to the power supply via an amplifier 11 by a setting device (not shown). is input to the device 12, and the power supply device 12 outputs the corresponding excitation current ■0, and each electromagnet 5
generates an electromagnetic force FO.

Here, this electromagnetic force F is generally expressed by the following formula.

g=I, +-t -'L Fist・Fist・(2
) However: Constants: Electromagnet excitation current g: Gap between the electromagnet and the steel plate surface Ll: Distance between the electromagnet and the detector t: Plate thickness/A) The detection signal from the distance detector 10 is The floating position of the steel plate is controlled to be constant through so-called proportional → -derivative control. Note that the differential control is for improving responsiveness by applying a large corrective action at the beginning of a deviation in proportion to the differentiation of the deviation.

When transporting with a conventional roller table, it was necessary to repair the back side by approximately 500 mm per approximately 3,000 thick plates, but with the present invention, the amount of repair could be reduced to zero.

<Effects of the Invention> As mentioned above, according to the present invention, the steel plate is conveyed using a magnetic levitation method and the levitated position of the steel plate is always maintained constant, so both sides of the steel plate can be coated simultaneously and easily, reducing processing time. It is possible to achieve a constant coating film thickness, eliminate the need for repairs, and significantly reduce costs.

Furthermore, there is no need to invert the steel plate, and the operation is easy and the equipment can be relatively simple.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a coating device according to the present invention, FIG. 2 is a schematic plan view of FIG. 1, and FIG. 3 is a perspective view of a conveyance path.
FIG. 4 is a circuit diagram of the control mechanism. 1. Painting room, 2. Drying room, 3. Conveyance path, 6A...
Dummy roller, 3B...Guide roller, 4...Electromagnet,
5... Painter, 6... Roller table for carrying out, 7... Duct, 8... Blower 19... Dust collector, 1o... Distance detector, 11... Amplifier, 12... Power supply, 13... Differential element.

Claims (2)

[Claims] (1) The conveyed steel plate is suctioned and levitated by a large number of electromagnets arranged above the conveyance path, and is conveyed by switching the excitation of the electromagnets, while the front and back surfaces of the steel plate are painted with a coating machine, and then the conveyance path A steel plate characterized in that the distance to the steel plate is detected by a number of distance detectors disposed below, and the current of the electromagnet is controlled based on the detection result to maintain a constant distance to the steel plate. How to paint. (2) A sealed painting chamber and drying chamber in which a conveyance path having guide rollers that guide the side portion of the steel plate extends from the outside to the inside, and a plurality of conveyance paths arranged in the longitudinal and width directions above the conveyance path. electromagnets installed in the coating chamber that can suction levitate and transport the steel plate; paint machines installed in pairs above and below in the coating chamber to paint the front and back surfaces of the steel plate; and a number of paint machines installed below the conveyance path to detect the distance to the steel plate. , a distance detector that outputs a result, and a control mechanism that compares the output signal from this detector with a set value and controls the current of an electromagnet based on this result. .