JPH0557336B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a continuous annealing method and apparatus for steel plates, and particularly relates to a method and apparatus that are compact and enable long-term overaging treatment. .

(Prior art) As is well known, in continuous annealing of steel plates, the steel plate after cold rolling is heated to a temperature of about 700 to 850°C.
Thereafter, the steel is soaked for about 1 minute to recrystallize it, and then rapidly cooled to about 400°C to bring the carbon in the steel into a supersaturated state. Subsequently, an overaging treatment is performed for 2 to 3 minutes in a furnace at about 400°C to precipitate solute carbon that is harmful to the workability of the product steel sheet.

Although such a conventional heat cycle is sufficient for manufacturing steel sheets for general processing, it is insufficient for deep drawing steel sheets, especially for applications that require high workability of the DDQ class. The reason for this is that the above-mentioned over-aging treatment of about 2 to 3 minutes has not yet precipitated solute carbon to a sufficient level, and due to aging deterioration after steel plate production, the yield point increases, the elongation decreases, and the yield point elongation increases. This is because it causes deterioration in workability such as the occurrence of. As a countermeasure to this problem, a method has been adopted in which carbon is reduced as much as possible during the steelmaking stage, and the trace amount of remaining carbon is fixed as a compound by adding titanium or the like to produce highly workable steel sheets that do not require over-aging treatment. Material costs will increase. In addition, in order to obtain high workability with ordinary inexpensive materials (carbon content 0.03 to 0.05%), long-term overaging treatment is required, but in conventional vertical furnaces with large-diameter hearth rolls, The scale of the equipment was enormous, and it was impractical.

Aging deterioration is generally evaluated by an aging index, and it is said that it is possible to manufacture DDQ if the index is approximately 3 kg/mm ² or less. With the above-mentioned inexpensive materials, the overaging time required to achieve this aging index of 3 kg/mm ² or less is said to be 10 minutes or more. In other words, an overaging time that is more than five times longer than a conventional heat cycle is required, and if this were to be achieved using a normal vertical furnace, the overaging furnace would have a furnace height of 25 m and a furnace length of over 150 m. ,
It was just completely unrealistic.

(Problems to be Solved by the Invention) In order to perform long-term overaging, the present inventors proposed a continuous annealing method using a circular spiral overaging furnace in Japanese Patent Application Laid-Open No. 59-222534.

The outline is shown in Figure 6. A steel plate 1 sent out from a primary cooling zone (not shown) is a helical turn device 1
1, and overlapped with the guide steel plate 2 coming from the opposite direction, the guide roller group 15 arranged radially with respect to the center of the spiral causes the guide roller to travel from the outside to the inside in a spiral path.

The guide steel plate 2 that has come to the innermost side is turned by the helical turn device 12 and sent out to the outside of the spiral path, and is turned by the helical turn device 13 and overlapped with the steel plate 1.

On the other hand, the innermost steel plate 1 is separated from the guide steel plate when passing through the helical turn device 12, and is turned by the helical turn device 14 to head toward a secondary cooling zone (not shown).

Further, Japanese Patent Application Laid-Open No. 145325/1983 discloses a device in which the circular spiral overaging furnace is arranged vertically. However, since the spiral overaging furnace has a circular external shape, if there are restrictions on the width or height of the building, the desired radius cannot be obtained. It may not be long enough.

(Means/effects for solving the problems) The present invention has been made to solve the above-mentioned problems, and it is a continuous annealing method for steel plates that can be subjected to long-term overaging treatment even when there are restrictions on the building. A method and apparatus are provided.

The gist is that in a continuous annealing method for steel plates in which the steel plates are sequentially passed through a heating zone, a soaking zone, a primary cooling zone, an overaging zone, and a secondary cooling zone, the steel sheet sent out from the primary cooling zone is run at the same speed. The steel plate is superimposed on an endless guide steel plate and is run from the outer periphery to the inner periphery or from the inner periphery to the outer periphery while being supported by an oval spiral traveling furnace composed of a group of guide rollers. The direction of the guide steel plate is changed and the guide steel plate is guided out of the vortex running furnace, and the steel plate and the guide steel plate are separated.The guide steel plate returns to the outermost or innermost periphery of the vortex running path, and the steel plate is guided to the following secondary cooling zone. This method is a continuous annealing apparatus for steel sheets having a heating zone, a soaking zone, a primary cooling zone, an overaging zone, and a secondary cooling zone.
The inlet passage communicates with the primary cooling zone, the outlet passage communicates with the secondary cooling zone, and has an oval spiral running path formed by a large number of support rollers inside, and processes the spiral running path. An endless guide steel plate that supports and circulates the steel plate to be processed is arranged on a support roller, a device for overlapping the steel plate and the guide steel plate is placed on the entry side of the spiral running path, and a device for separating the steel plate and the guide steel plate is placed on the entrance side of the spiral running path. This is a continuous annealing device for steel sheets, characterized in that each device is disposed on the exit side.

Here, the ellipse includes a shape in which each corner of a rectangle is a quarter arc.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

FIG. 1 shows rectangular spiral running paths arranged in a vertical plane.

The steel plate 1 to be processed, which has passed through the heating zone, soaking zone, and temporary cooling zone, is overlapped with the endless guide steel plate 32 by rolls 75 and 76 for overlapping installed at the entrance of the spiral travel path, and the steel plate 1 is overlapped with the endless guide steel plate 32, and the steel plate 1 is overlapped with the endless guide steel plate 32 by the rolls 75 and 76 for overlapping installed at the entrance of the spiral travel path. The road is circulated from the outer circumferential side to the inner circumferential side.

The steel plate 1 and the guide steel plate 32 that have reached the innermost periphery are turned in their traveling direction by a turning roll 78 and guided inside the spiral traveling path, and then the traveling surface is changed by a helical turn device 80 to create a spiral. The helical turn device 81 is guided to the outside of the running path.
The surface of the steel plate is changed to horizontal.

A roll 88 for separating the steel plate and the guide steel plate is installed in the communication passage from the overaging zone to the secondary cooling zone (in Fig. 1, from the innermost exit of the volute running path to the entrance of the secondary cooling zone). Here, steel plate 1
The guide steel plate 32 is separated, the steel plate is directed to the secondary cooling zone, the guide steel plate 32 is again directed to the entrance of the overaging zone, and is overlapped with the steel plate 1 again by the rolls 75 and 76 and directed to the spiral running path.

The total length L of the steel plate in the oval spiral running path is the first
As shown in the figure, if the width of the outer periphery of the spiral is H, the height is V, the outer radius of the arc portion is r ₂ , the inner radius is r ₁ , and the pitch of the spiral is p, then L = (r ₂ − r ₁ /p+1 ) {2(H+V-4r ₂ ) +π(r ₁ +r ₂ )}.

As an example of specifications, in order to apply overaging treatment for 10 minutes in a continuous annealing furnace with a line speed of 300 m/min, L = 10 minutes x 300 m/min = 3000 m is required.
This is r ₁ = 2m, r ₂ = 7m, p = 0.19m, H = 50
This can be achieved with the specifications of m and V = 20m.

Here, the ratio of the long axis H to the short axis V is greater than 1, but as this ratio increases, it approaches a conventional vertical furnace, so it is desirable to have a ratio of 4 or less.

In addition, in the horizontal portion of the spiral travel path, the guide steel plate 32 is supported by the guide roller 3 arranged in a horizontal position. Further, as a method of supporting the guide steel plate 32 in the arc portion, guide rollers 30a having grooves are arranged radially with respect to the center of the arc, as shown in the upper left of FIG. 1 and details in FIG. The guide steel plate 32 may be supported by a roller 30b whose rotation axis is horizontal, as shown in the upper right part of FIG. 1 and details in FIG. 4.
Although the latter has higher equipment costs than the former, the life of the guide steel plate 32 is longer because the load is supported over the entire width of the guide steel plate 32.

Although the embodiment shown in FIG. 1 shows an example in which the spiral travel path is arranged in a vertical plane, it may also be arranged in a horizontal plane. In addition, the stacked steel plates and guide steel plates ran from the outside to the inside of the spiral running path, but if the traveling direction was reversed, the stacked steel plates and guide steel plates ran from the inside of the spiral running track to the outside. I will be driving towards it.

Figure 2 shows the first part of the helical turn device.
The AA cross section of the figure is illustrated. The steel plate and the guide steel plate that have advanced from the rear in the figure are wound around a helical turn device 80 having a spiral path to change the direction of travel and the surface of travel, and then are turned downward by a turning roll 82, and further turned by a turning roll. 84, it travels horizontally, is wound around a helical turn device 81 having a spiral path, changes its traveling direction and plane, and travels toward the rear of the page.

FIG. 5 is an overall view of a continuous annealing furnace using the technique of the present invention. Steel plate 1 has heating zone 11 and soaking zone 1
2. Passing through the primary cooling zone 13, it enters the overaging zone 14 according to the present invention.

Thereafter, it passes through the secondary cooling zone 15 and is sent to the outlet looper. As is clear from FIG. 5, by using the technique of the present invention, not only can a long-term overaging treatment be carried out in a compact furnace, but it can also be carried out even if there are restrictions on the height or width of the building.

(Effects of the Invention) As described above, according to the present invention, long-term over-aging treatment can be performed without stopping the running of the steel plate, and it is possible to carry out long-term over-aging treatment without stopping the running of the steel plate. can also be easily implemented.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, in which an overall view of an overaging zone in which an oval spiral running path is arranged in a vertical plane, and FIG. 2 is a sectional view taken along the line A-A in FIG. 3 is a detailed view of one embodiment of the guide roller, FIG. 4 is a detailed view of another embodiment of the guide roller, FIG. 5 is an overall view of a continuous annealing furnace having an oval spiral running path, and FIG. FIG. 6 is an overall view of an overaging zone having a conventional circular spiral running path. 1... Steel plate, 30... Guide roller, 32...
Guide steel plate, 75, 76, 78, 82, 84, 8
8... Turning roll, 80, 81... Helical turn device.

Claims (1)

[Scope of Claims] 1. In a continuous annealing method for a steel plate that provides a heat cycle of heating, soaking, primary cooling, overaging, and secondary cooling, the steel plate delivered from the primary cooling zone is run at the same speed. It is superimposed on an endless guide steel plate and is run from the outer circumference to the inner circumference while being supported by an oval spiral running path composed of a group of guide rollers, and the direction of the steel plate and the guide steel plate is changed at the innermost circumference. The steel plate is sent to the outside of the running path, the steel plate and the guide steel plate are separated, and the guide steel plate returns to the outermost periphery of the spiral running path,
A continuous annealing method for steel plates, characterized in that the steel plates are sent to a subsequent secondary cooling zone for cooling. 2. In a continuous annealing method for steel plates that provides a heat cycle of heating, soaking, primary cooling, overaging, and secondary cooling, the steel plate sent out from the primary cooling zone is superimposed on a guide steel plate running at the same speed, The steel plate and the guide steel plate are guided to the innermost periphery and run from the inner periphery to the outer periphery while being supported by an elliptical spiral running path constituted by a group of guide rollers, and the direction of the steel plate and the guide steel plate is changed at the outermost periphery to form the running path. The steel plate and the guide steel plate are separated from each other, the guide steel plate is run to be overlapped with the steel plate delivered from the primary cooling zone, and the steel plate is sent to the subsequent secondary cooling zone for cooling. Continuous annealing method for steel plates. 3. In a continuous annealing apparatus for steel sheets having a heating zone, a soaking zone, a primary cooling zone, an overaging zone, and a secondary cooling zone, the overaging zone has an inlet passage communicating with the primary cooling zone, and an outlet passageway communicating with the primary cooling zone. communicates with the secondary cooling zone, has an oval spiral running path formed by a large number of support rollers inside, and an endless looped guide steel plate that supports the steel plate as it travels is placed on the support rollers. A device for overlapping the steel plate and the guide steel plate is placed on the entry side of the vortex running path, a device for separating the steel plate and the guide steel plate is placed on the exit side of the vortex running path, and the inlet passage and the exit passage of the over-aging zone are arranged respectively. A continuous annealing apparatus for steel plates, characterized in that one or more helical turn apparatuses are arranged between them. 4. The continuous annealing apparatus for steel plates according to claim 3, wherein the oval spiral running path is arranged in a horizontal plane. 5. The continuous annealing apparatus for steel sheets according to claim 3, wherein the oval spiral running path is arranged in a vertical plane. 6. The continuous annealing apparatus for steel plates according to claim 3, 4, or 5, further comprising a guide roller that supports the guide steel plate in a horizontal direction.