JPH07148454A - Baking furnace of metal strip coating line - Google Patents

Abstract

PURPOSE:To provide a baking furnace capable of reducing the initial cost and running cost of an induction heating coil. CONSTITUTION:The metal strip 2 fed in a baking furnace 3 in a catenary state is passed through the gap between a pa,i,; of induction heating coils 10a, 10b to be subjected to baking coating. The heating coil driving means 11 moving a pair of the induction heating coils up and down are arranged in the baking furnace 3 and position detection means 12a, 12b detecting the position of the metal strip in an up and down direction are arranged. The data of the metal strip in the up and down direction detected by the position detection means is inputted to a control part 13 and the control part outputs a drive signal to the heating coil driving means on the basis of this data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a baking furnace for a metal band coating line in which a metal band coated with a paint and conveyed in a catenary state is baked by an induction heating coil.

[0002]

2. Description of the Related Art A continuous coating line for steel strips (metal strips) is, as shown in FIG. 3, a steel strip 2 having a predetermined surface coated with a coater 1 in a coating process in a continuous baking furnace 3
It is configured to be conveyed inside and subjected to baking coating treatment, and further continuously conveyed to the cooling treatment device 4 to perform cooling treatment.

An induction heating coil 5 is arranged in the baking furnace 3 as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-8318 previously filed by the applicant of the present application. This induction heating coil 5
Are arranged above and below, facing the steel strip 2. When electric power is supplied, magnetic flux is generated in the thickness direction of the steel strip 2, and eddy currents are generated so as to interlink with the magnetic flux. The baking coating of the steel strip 2 is performed.

The steel strip 2 that is continuously conveyed is
A state of being bent downward with a predetermined catenary angle supported by a furnace entrance side roller 6 arranged on the inlet side of the baking furnace 3 and a furnace exit side roller 7 arranged on the cooling device 4 side (hereinafter , Abbreviated as a catenary state).

[0005]

By the way, the steel strip 2 is
When the welded part to which the steel strips having different plate thicknesses and widths are connected to each other moves into the baking furnace 3, the weight per unit length of the steel strip in the furnace changes, so that the steel strip further bends downward to form the catenary shape. May fluctuate. As a technique for suppressing the variation of the catenary shape, for example, as shown in Japanese Patent Laid-Open No. 3-6333 (in-furnace catenary control device), the variation of the catenary shape is predicted as the welded portion moves between the catenary supports. The technology that actually obtains a stable catenary shape of the steel plate by feedback-correcting the target catenary amount and performing feedback control using the catenary detector that detects the catenary shape is actually adopted. .

Here, the above-mentioned steel strip 2 into the baking furnace 3
The catenary shape may fluctuate due to external factors such as vibration of the steel strip 2 itself, instead of the movement of the welded part, and in that case, the steel strip 2 and the induction heating coil may come into contact with each other. . Such a change in the catenary shape due to an external factor is difficult to deal with by the technique of the in-reactor catenary control device described above.

Therefore, in the conventional induction heating heater, in order to prevent the contact between the steel strip 2 and the induction heating coil, the steel strip 2 is
The pair of induction heating coils 5 that are vertically arranged so as to face each other is arranged with the coil interval widened. However,
In order to apply a predetermined amount of heat to the steel strip 2 by the pair of induction heating coils that are arranged apart from each other, a large amount of electric power needs to be supplied to the induction heating coil. There is a problem to be solved in terms of initial cost and running cost spent on the heating coil.

The present invention has been made in view of the above-mentioned unsolved problems, and provides a baking furnace for a metal strip coating line capable of reducing the initial cost and running cost of the induction heating coil. The purpose is to

[0009]

In order to achieve the above object, a baking furnace of a metal strip coating line according to the present invention uses a metal strip for heating a metal strip conveyed into the furnace in a catenary state. It is a baking furnace of a metal strip coating line, which is provided with a pair of induction heating coils arranged facing each other. In this baking furnace, heating coil driving means for moving the pair of induction heating coils in the vertical direction, position detection means for detecting the vertical position of the metal strip at the position where the pair of induction heating coils are arranged, and this position There is provided control means for driving the heating coil driving means so that the distance between the induction heating coil and the metal strip becomes a predetermined distance based on the vertical position of the metal strip detected by the detection means.

[0010]

According to the baking furnace of the metal strip coating line of the present invention, when the metal strip between the pair of induction heating coils is located on the lower side due to the change in the catenary state of the metal strip,
The position detection means detects the vertical position of the metal strip. Then, the control means to which the data of the vertical position of the metal strip is input from the position detecting means calculates the downward movement amount of the heating coil driving means based on the data. Then, the control means controls the heating coil drive means by a predetermined amount of movement, whereby the pair of induction heating coils moves downward, and the metal strip is positioned at an intermediate position between these induction heating coils. On the other hand, when the metal band between the pair of induction heating coils is located on the upper side due to the change in the catenary state of the metal band, the control means to which the data of the vertical position of the metal band is input from the position detection means, The amount of upward movement of the heating coil driving means is calculated based on the data. Then, the control means controls the heating coil drive means by a predetermined amount of movement, whereby the pair of induction heating coils moves upward, and the metal strip is positioned at an intermediate position between these induction heating coils.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. The same components as those shown in FIG. 3 will be assigned the same reference numerals and explanations thereof will be omitted. FIG. 1 is a system diagram showing an apparatus for a baking furnace, which is a hydraulic cylinder (heating coil driving means) capable of simultaneously moving a pair of induction heating coils 10a, 10b arranged in the furnace in the vertical direction.
11 and a position sensor (position detecting means) 12a arranged to face the steel strip 2 on the upstream side and the downstream side in the transport direction of the steel strip 2 so as to sandwich the induction heating coils 10a and 10b.
12b and a control unit (driving means) 13 for controlling the drive of the hydraulic cylinder 11 are provided.

The steel strip 2 which has been conveyed into the furnace in a catenary state from the coating process passes between a pair of induction heating coils 10a and 10b which are opposed to each other with a predetermined space H, and a cooling device 4 is provided. Is transported to the side. Here, the induction heating coils 10a and 10b are integrated by the connecting member 10c. And the induction heating coil 10a,
By supplying a predetermined electric power to 10b, a magnetic flux is generated in the plate thickness direction of the steel strip 2, and an eddy current is generated so as to interlink with the magnetic flux, so that the steel strip 2 is baked and coated. ing.

A cylinder body 11a constituting the hydraulic cylinder 11 is connected to a predetermined position in the furnace and
The tip of the cylinder rod 11b, which is vertically movable from the cylinder body 11a, is connected to the bottom of the induction heating coil 10b. When a predetermined drive signal C _K is input from the control unit 13, the cylinder rod 11b moves forward and backward, and the induction heating coils 10a and 10b move in the vertical direction by a predetermined amount.

The position sensors 12a and 12b are laser length measuring machines.
The position facing the steel strip 2 in the furnace.
Is fixed to the steel strip 2 and the distances Ca and Cb from the steel strip 2 are measured and
A signal is input to the control unit 13. Also,
The control unit 13 includes an input interface circuit and an output interface circuit.
Interface circuit, arithmetic processing unit, RAM, ROM, etc.
Microcomputer having a memory device (not shown)
Is equipped with. Here, the storage device includes an induction heating coil.
Coil center position D between 10a and 10b_P(Shown in Figure 2
The predetermined reference position D₀Induction heating coil 10a,
The height up to the central position between 10b) is stored. So
Then, with the steel strip 2 actually measured by the position sensors 12a and 12b,
Signals at distances Ca and Cb are input interface circuits
When input via
Based on the signal of b, the current position Dc of the steel strip 2 (shown in FIG. 2)
The predetermined reference position D₀To the center of steel strip 2 thickness
Height) is calculated. At the same time, the arithmetic processing unit
The current position Dc of the steel strip 2 and the coordinates stored in the storage device.
Il center position D_PCalculate the deviation distance ΔD from
The calculated deviation distance ΔD is the drive signal C_KSet as and output
Output to hydraulic cylinder 11 via interface circuit
It is supposed to do. In addition, the present of the calculated steel strip 2
The position Dc is the coil center position D _PUpdate to storage as
It is supposed to be remembered.

According to the above construction, as shown in FIG. 2, when the steel strip 2 between the induction heating coils 10a and 10b is located on the lower side due to the change in the catenary state of the steel strip 2, the position Distances Ca and Cb with the steel strip 2 measured by the sensors 12a and 12b are input to the control unit 13, and the control unit 13
Calculates the current position Dc of the steel strip 2 from the signals of the distances Ca and Cb from the steel strip 2, and calculates the deviation distance ΔD between the current position Dc of the steel strip 2 and the stored coil center position D _P. The calculated deviation distance ΔD is set as the drive signal C _K. Then, by outputting the drive signal C _K to the hydraulic cylinder 11, the hydraulic cylinder 11
Causes the cylinder rod 11b to be retracted by a predetermined distance, and as shown by the chain double-dashed line in FIG.
A and 10b are moved downward by a predetermined amount. As a result, the current position Dc of the steel strip 2 and the coil center position D _P coincide.

Further, even when the steel strip 2 between the induction heating coils 10a and 10b is located on the upper side due to the change in the catenary state of the steel strip 2, the drive signal C _K is sent from the control unit 13 to the hydraulic cylinder 11. Output, cylinder rod 11b
The induction heating coils 10a, 10
By moving b to the upper side by a predetermined amount, the steel strip 2
The current position Dc and the coil center position D _P coincide with each other.

Therefore, according to this embodiment, even if the shape of the catenary fluctuates due to external factors such as the vibration of the steel strip 2 itself, the induction heating coils 10a and 10b follow it.
Also moves in the vertical direction, and always the induction heating coils 10a, 1
Since the steel strip 2 is automatically controlled so that the steel strip 2 is located at the central portion of 0b, there is no risk of contact between the steel strip 2 and the induction heating coils 10a, 10b, and the contact is prevented as in the conventional induction heating heater. Therefore, the initial cost and the running cost can be significantly reduced without increasing the coil interval to supply a large amount of electric power.

In this embodiment, two position sensors are used. However, a plurality of position sensors are arranged to face the steel strip 2, and the actual measurement value of the steel strip 2 is input to the control unit 13 so that a higher value can be obtained. It is possible to accurately control the movement of the induction heating coils 10a and 10b. Further, the hydraulic cylinder 11 used in the present embodiment is not limited to this, and is a device capable of raising and lowering the induction heating coils 10a and 10b by a predetermined amount when a drive signal is input from the control unit 13. If,
Devices with other features may be used.

[0019]

As described above, according to the baking furnace of the metal strip coating line of the present invention, even if the catenary shape of the metal strip fluctuates due to external factors such as vibration of the metal strip itself, Control is performed to move the pair of induction heating coils by following up and down movements, and the metal strip can be always positioned in the center between the induction heating coils.
There is no risk of contact between the metal band and the induction heating coil, and there is no need for large-capacity power supply due to the expansion of the distance between the coils as with conventional induction heating coils, and the initial cost and running cost can be significantly reduced. .

[Brief description of drawings]

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

FIG. 2 is a schematic diagram showing the operation of the present invention.

FIG. 3 is a schematic view showing a metal strip coating line.

[Explanation of symbols]

 2 Metal strip (steel strip) 3 Baking furnace 10a, 10b Induction heating coil 11 Heating coil drive means (hydraulic cylinder) 12 Position detection means (position sensor) 13 Control section (control means)

Claims (1)

[Claims] 1. A baking furnace of a metal strip coating line, comprising a pair of induction heating coils arranged vertically to face the metal strip in order to heat the metal strip conveyed into the furnace in a catenary state, Heating coil drive means for moving the pair of induction heating coils in the vertical direction, position detection means for detecting the vertical position of the metal strip at the position where the pair of induction heating coils are arranged, and the position detection means for detecting the position. A metal strip coating, comprising: a control unit that drives the heating coil driving unit so that a distance between the induction heating coil and the metal strip becomes a predetermined distance based on a vertical position of the metal strip. Line baking furnace.