JPS6343450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a vertical continuous annealing apparatus, and more specifically, to a hearth located in a high-temperature treatment zone in a vertical continuous annealing furnace used for heat treating strip-shaped metal materials. The present invention relates to a continuous annealing apparatus in which a cylindrical roll is disposed in the vicinity of a cylindrical roll and has a fixed position relative to the cylindrical roll in order to prevent meandering and buckling of the strip-shaped metal material.

[Background of the Invention] A continuous annealing furnace is composed of heating, soaking, and cooling zones from the upstream side, and the strip-shaped metal material is subjected to appropriate heat treatment according to the purpose while passing through these zones sequentially. .

In a vertical continuous annealing furnace, a large number of hearth rolls are arranged in parallel at the top and bottom of the furnace, and the strip metal material is guided by these hearth rolls and passes through each zone in the furnace while moving up and down in the vertical direction. do.

Operational problems with such equipment include:
There are two problems: the belt-shaped metal material meandering in the width direction and the problem that buckling occurs within the belt-shaped metal material.

Conventionally, this problem has been avoided by employing a hearth roll shape with a medium-high crown, which applies the same principle as that used to prevent meandering in so-called belt pulleys, as a means for preventing meandering of the above-mentioned belt-shaped metal material.

For example, the hearth roll drum has a tapered shape, that is, the center of the drum is cylindrical, and both ends have conical tapers;
Alternatively, use a hearth roll with an arcuate crown shaped like a beer barrel on the outer peripheral surface.

Hearth rolls with such a shape have the function of preventing meandering of the strip metal material, but if the inclination angle of the taper is large, the curvature of the crown is too large, or the longitudinal tension of the strip metal material is increased. In some cases, non-uniform tensions occur within the plane of the metal strip, which results in the induction of compressive stresses within the metal strip. This compressive stress causes a new problem in that buckling occurs within the band-shaped metal material.

This buckling not only causes the strip metal material to lose its value as a product, but in severe cases, it may cause the strip metal material to break in the annealing furnace.
It may cause big trouble.

If you reduce the taper amount or crown amount of the hearth roll or reduce the longitudinal tension of the metal strip to prevent buckling, the hearth roll's ability to prevent the metal strip from meandering will be lost. The belt-shaped metal material cannot be transferred properly, and in severe cases, the belt-shaped metal material may come off the hearth roll and cause a serious problem in that both ends of the metal material scrape against the furnace wall.

If the shape of the hearth roll and the size, shape, and tension of the metal strip are appropriately combined, there will be a region where neither meandering nor buckling occurs. However, the shape of the hearth roll is determined at the time of construction of the furnace, but on the other hand, the dimensions such as width and thickness of the strip metal material to be continuously annealed, the material, high-temperature strength, heat treatment conditions, etc. vary widely. Therefore, it is impossible to design the shape of the hearth roll so that meandering and buckling do not occur in all cases, and other measures are required.

In view of the above circumstances, the present inventors have conducted various studies and found that if a cylindrical roll is attached to an appropriate position immediately before and after the attachment of the strip-shaped metal material to the lotus roll and the strip-shaped metal material is brought into contact with the cylindrical roll, the strip-shaped metal material can be Even if a large longitudinal tension is applied to prevent meandering, the problematic buckling does not occur, and the meandering of the strip metal material,
It has been found that this method is extremely effective in preventing both buckling, and has already provided a device having meandering and buckling prevention functions for hearth rolls in Japanese Patent Application No. 188257/1983.

The present invention is a further development of this solution.

[Purpose and summary of the invention]

The purpose of the present invention is to quantify through experiments the optimal placement position of the above device equipped with cylindrical rolls, and to prevent buckling within the band-shaped metal material even when a large longitudinal tension is applied to the band-shaped metal material to prevent it from meandering. It is an object of the present invention to provide an annealing apparatus that can simultaneously prevent meandering and buckling of a band-shaped metal material without causing such occurrence.

Another object of the present invention is to provide an annealing apparatus capable of continuously annealing a strip-shaped metal material under extremely wide range of conditions.

In the present invention, a cylindrical metal material is attached to a belt-shaped metal material wrapped around the hearth roll, substantially parallel to the hearth roll axis, in the vicinity of a hearth roll located in a high-temperature treatment area in a vertical continuous annealing furnace. (A) In the first invention, the hearth roll and the cylindrical roll attached close to the hearth roll are in contact with different surfaces of the strip-shaped metal material. (B) In the second invention, the hearth roll and the cylindrical roll attached close to it are defined as follows: When contacting the same surface of the band-shaped metal material, the relative position thereof is lV/DH≦3.6 lH/DH≧0.59−0.5DA/DH.

Where, lV: Vertical distance between hearth roll axis and cylindrical roll axis lH: Horizontal distance between hearth roll axis and cylindrical roll axis DH: Hearth roll outer diameter DA: Cylindrical roll outer diameter be.

According to the present invention, a cylindrical roll is provided at the most effective position to correct the deformation that occurs in the band-shaped metal material in a position close to the hearth roll in a high temperature area, and the meandering of the band-shaped metal material and the deformation that occurs in the band-shaped metal material are corrected. Buckling can be prevented at the same time.

[Detailed description of the invention]

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIGS. 1 and 2 illustrate the shape of a hearth roll for preventing meandering of a metal band.

Fig. 1 shows a tapered hearth roll, and Fig. 2 shows a round crown roll.

The continuous annealing apparatus heat-treats the strip-shaped metal material 2 by passing it through a heating zone 4, a soaking zone 5, and a cooling zone in sequence, as shown in a schematic longitudinal cross-sectional view in FIG. They are installed parallel to each other at the top and bottom. The strip-shaped metal material 2 is guided by these hearth rolls 1 and sequentially passes through each part of the furnace.

If the taper inclination angle θ of the tapered hearth roll shown in FIG. 1 or the curvature 1/ρ of the round crown roll shown in FIG. Non-uniform compressive stress occurs within the plane of the strip-shaped metal material, causing buckling within the strip-shaped metal material. To prevent such buckling and at the same time meandering, it is possible to
This is possible as long as the combination of the shape of the hearth roll and the dimensions, shape, and tension of the strip-shaped metal material is within an appropriate range.

FIG. 3 is a diagram schematically showing this.
In the figure, the hatched area on the lower left side indicates the area where meandering occurs, and the shaded area on the upper right side is the area where buckling occurs. Between these two areas there is a region where neither of these occurs. In other words, under the same tension, the inclination angle θ and curvature 1/ρ of the hearth roll taper prevent both meandering and buckling.
There is a limited tension range of appropriate values. However, in general, in a continuous annealing furnace, the dimensions (thickness, width) and material (high temperature strength, heat treatment conditions) of the strip metal material change significantly, so the appropriate area shown in Figure 3 varies accordingly. fluctuate.

On the other hand, the shape of the hearth roll is determined at the time of facility construction, and replacing this roll is a difficult task and takes a very long time. Therefore, it is extremely difficult to perform replacement work each time following changes in the operating conditions.

In the present invention, a cylindrical metal material is crimped onto a belt-shaped metal material wound around the hearth roll, substantially parallel to the hearth roll axis, in the vicinity of a hearth roll located in a high-temperature treatment area in a vertical continuous annealing furnace. A continuous annealing apparatus equipped with a shaped roll, characterized in that the hearth roll and the cylindrical roll attached close to the hearth roll are arranged in a fixed relationship position, the continuous annealing apparatus being This simultaneously prevents meandering and buckling that occurs within the band-shaped metal material.

Figures 4 and 5 show a hearth roll 1, a cylindrical roll 6, and a part of a metal strip 2 in a heating zone 4 and a part of a soaking zone 5, which are high-temperature heat treatment areas of a vertical continuous annealing furnace.
The positional relationship is shown schematically. 4 and 5 show an embodiment in which a cylindrical roll 6 is installed in a position close to two upper rolls at the rear end of the heating zone 4 and two upper rolls at the front end of the soaking zone 5. be. Figures 4 and 5
In the figure, the belt-shaped metal material 2 is arranged so as to be pushed in just before it is wound around the hearth roll 1, that is, the back side of the surface in contact with the hearth roll 1 is in contact with the cylindrical roll 6.

In the embodiment of the present invention shown in FIG. 5, FIG. 11 shows the appearance shape of the wrinkles 7 that occur in the band-shaped metal material 2 just before it is wound around the hearth roll 1.
The AA arrow view is shown in FIG.

FIG. 13 shows the appearance shape of wrinkles 7 that occur in the band-shaped metal material 2 immediately before it is wound around the hearth roll 1 in a conventional annealing apparatus. FIG. 14 is a view taken along the line B--B. As is clear from Fig. 13, when tension is applied to the strip-shaped metal material in the longitudinal direction, compressive stress in the width direction occurs in the portion corresponding to the tapered shoulder of the hearth roll, causing the strip-shaped metal material to Large wrinkles 7 occur in the material. In this state, the strip-shaped metal material wraps around the hearth roll, causing problematic buckling wrinkles.

However, the eleventh case using the cylindrical roll 6 of the present invention
In the case of Fig. 12, compared to the conventional Fig. 13 and Fig. 14, the shape of the wrinkles is gentle due to the effect of flattening the band-shaped metal material 2 with the cylindrical roll 6,
Therefore, buckling wrinkles are less likely to occur. The above is the principle of preventing buckling wrinkles caused in the band-shaped metal material 2 by the cylindrical roll 6.

6 to 9 show the relative positional relationships between various rolls when the strip metal material comes into contact with the cylindrical roll 6 before and after the hearth roll 1.

FIG. 6 shows an embodiment in which a cylindrical roll 6 is installed immediately before the belt-shaped metal material 2 is wound around the hearth roll 1 on the upstream side so that the same surface of the belt-shaped metal material is in contact with the hearth roll 1 and the cylindrical roll 6. ing.

In FIG. 7, cylindrical rolls 6 are installed just before and after winding, that is, on both the upstream and downstream sides.

FIG. 8 shows an embodiment in which a cylindrical roll 6 is installed immediately before the upstream side where the hearth roll 1 and the band-shaped metal material 2 are wound, so that the cylindrical roll 6 contacts a surface different from the surface of the band-shaped metal material that the hearth roll 1 contacts. It is.

FIG. 9 shows an example in which, in addition to the embodiment shown in FIG. 8, a cylindrical roll 6 is installed immediately after winding, that is, on the downstream side.

FIG. 10 shows a conventional embodiment in which the cylindrical roll 6 is not used for comparison.

When the band-shaped metal material is wound around the hearth roll 1, which side of the band-shaped metal material is more likely to buckle, the upstream part or the downstream part of the hearth roll, is lower on the upstream side. It is known that buckling occurs due to tension. Therefore, in order to prevent buckling of the band-shaped metal material, the first thing that is important is to install a cylindrical roll upstream of the part where the band-shaped metal material 2 is wound around the hearth roll, as shown in FIGS. 6 and 8. 6 to correct wrinkles that occur in the band-shaped metal material. Furthermore, for materials with thin plate thickness and low yield stress, that is, materials with low buckling resistance, a cylindrical roll 6 for wrinkle correction is installed on the exit side of the hearth roll as shown in Figures 7 and 9. It is desirable to place them together.

The following will explain which surface of the strip-shaped metal material 2 it is advantageous to bring the cylindrical roll 6 into contact with.

8 and 9 in which the cylindrical roll 6 is arranged so as to push the band-shaped metal material 2, and the case in Fig. 6 in which the cylindrical roll 6 is arranged so as to push out the band-shaped metal material 2.
There is almost no difference in the difficulty of buckling occurring in the cases shown in Fig. 7 and Fig. 7. This will be clarified in later experimental examples. In either case, buckling does not occur up to a higher tension than in the conventional embodiment shown in FIG. However, when focusing on preventing meandering of the material, it is better to arrange the cylindrical roll 6 so as to push the band-shaped metal material 2 as shown in FIGS. 8 and 9. This embodiment is more advantageous in preventing the belt-shaped metal material from meandering than the embodiment shown in , in which the belt-shaped metal material 2 is extruded. This is because the winding angle of the band-shaped metal material 2 around the hearth roll 1 can be increased, so that the meandering prevention function of the hearth roll is increased.
Next, a description will be given of how much tension causes buckling due to a change in the relative position of the cylindrical roll 6 with respect to the hearth roll 1.

The results of the experimental investigation are as follows: First, in the case shown in FIG. The case where it is brought into contact with is explained below.

FIG. 15 shows the critical tension Tcr at which buckling begins when the relative position of the cylindrical roll 6 with respect to the hearth roll 1 is changed and the material tension is increased.

This experiment was conducted with the outer diameter D _H of the hearth roll being 600 mm and the outer diameter D _A of the cylindrical roll being 300 mm. The horizontal axis in FIG. 15 is a dimensionless value obtained by dividing the horizontal distance l _H between the center axis of the hearth roll 1 and the center axis of the cylindrical roll 6 by the hearth roll outer diameter D _H. The smaller the horizontal distance l _H , the smaller the cylindrical roll 6
In this case, the extent to which the band-shaped metal material 2 is pushed becomes large. On the other hand, when l _H /D _H becomes 0.75 or more, the cylindrical roll 6 and the band-shaped metal material 2 separate, and the effect of the cylindrical roll to flatten the band-shaped metal material is lost, resulting in the same state as in the conventional mode. The vertical axis in FIG. 15 is the vertical distance l _V between the central axis of the hearth roll 1 and the central axis of the cylindrical roll 6.
is divided by the outer diameter D _H of the hearth roll. The number shown in the circle in the graph of FIG. 15 is the critical tension Tcr (Kg/mm ² ) at which buckling begins to occur.

The hatched area on the left side of FIG. 15 is the limit tension Tcr in the conventional state where the cylindrical roll 6 and the band-shaped metal material 2 are not in contact,
Buckling occurs when the material tension exceeds 0.25Kg/ ^mm2 . As the horizontal distance l _H decreases, that is, as the horizontal distance between the hearth roll 1 and the cylindrical roll 6 approaches, the critical tension Tcr increases, the tension at which buckling occurs increases, and buckling becomes less likely to occur.

The conventional critical tension Tcr in Fig. 15 is
0.25Kg/mm ² , but in practice, if it is possible to pass the strip metal material through the high temperature range of a continuous annealing device with a tension of 1.5 times that, or 0.375Kg/mm ² or more, then the strip metal material The meandering correction is also carried out smoothly.

Therefore, from the experimental results shown in Fig. 15, the cylindrical roll should be installed at the following positions: l _V /D _H ≦3.6 (1) l _H /D _H ≦0.65 (2a). however,
When the outer diameter D _A of the auxiliary roll 6 changes, even if the horizontal distance l _H is constant, the amount of indentation of the strip metal material (0.5 (D _A + D _H ) - l _H ) actually changes.
If this minimum pushing amount is ensured and the cylindrical roll diameter D _A is taken into account, the above equation (2a) can be rewritten as the following equation.

l _H ／D _H ≦0.41＋0.5D _A ／D _H ...(2) Next, the experimental results for the case of FIG.
Shown in the figure. Both the horizontal and vertical axes in FIG. 16 are the same as in FIG. 15. In the case of FIG. 16, the larger the horizontal distance l _H between the hearth roll 1 and the cylindrical roll 6, the more the cylindrical roll 6 pushes out the strip metal material 2, and when l _H /D _H becomes 0.25 or less, The cylindrical roll 6 and the band-shaped metal material 2 are separated, and the cylindrical roll no longer has the effect of preventing buckling. The sloped part on the right side of FIG. 16 is a region where the cylindrical roll 6 and the band-shaped metal material 2 are not in contact, and is within the range of the critical tension Tcr in the conventional method. 16th
The shaded area in the upper left of the figure is the area where the critical tension Tcr is high, where buckling is unlikely to occur, and similar to equations (1) and (2) above,
This dimensionless area using D _A /D _H is expressed as follows.

l _V /D _H ≦3.6 ... (1) l _H /D _H ≧0.59−0.5D _A /D _H ... (3) [Example] Next, the results of confirming the effects of the present invention with an actual machine will be explained. . Immediately upstream of each of the two upper hearth rolls 1 on the outlet side of the heating zone 4 and the upper hearth rolls 1 on the input side of the soaking zone 5 shown in FIG.
A cylindrical roll 6 was attached to each portion immediately before the band-shaped metal material 2 was wound around the hearth roll 1.

The relative position between the cylindrical roll 6 and the hearth roll 1 is indicated by an asterisk in FIG. 15. That is, l _H /D _H =0.60 l _V /D _H =2.2.

Hearth roll 1 is a tapered roll, with a width of the parallel part at the center: 460 mm, a taper on both sides: tanθ=0.0009 (where θ is the taper inclination angle), and an outer diameter (D _H ): 600 mmφ. The cylindrical roll 6 is cylindrical and has an outer diameter (D _A ) of 300 mmφ.

The band metal material is made of ultra-low carbon steel, Plate thickness: 0.7mm Board width: 1320mm Soaking zone temperature: 810℃ Threading speed: 200m/min heat treated.

Furthermore, as shown in FIG. 5, an industrial television 3 was installed at a position to observe the downstream portion of each hearth roll 1 of the strip-shaped metal material 2, and the meandering and buckling behavior of the strip-shaped metal material 2 was investigated.

The material tension T is gradually increased from 0.2Kg/ ^mm2 ,
The critical tension Tcr at which buckling occurs was determined.

The results are shown in FIG.

The shaded area on the lower side of FIG. 17 is an area where the material meanderes, and meandering occurs when T≦0.2 Kg/mm ² .

Therefore, in order to prevent meandering of the material, T>0.2
Requires operation at ~0.25Kg/ ^mm2 . When the tension T applied to the band-shaped metal material is increased, meandering no longer occurs, but the material begins to buckle. The conditions under which buckling does not occur are highlighted (○) in Figure 17.
The conditions under which buckling occurs are indicated by x marks. When cylindrical rollers are not installed, the tension range in which neither buckling nor meandering occurs is extremely narrow, 0.2Kg/mm ² < T < 0.25Kg/mm ² , and extremely severe operating conditions are forced.In contrast, in the case of the present invention. , the tension range in which neither buckling nor meandering occurs is 0.2Kg/mm ² <T < 0.44Kg/mm ² , and it is clear that the operating conditions are significantly relaxed.

[Brief explanation of the drawing]

Figures 1 and 2 are front views showing the appearance of the hearth roll, Figure 3 is a graph schematically showing the influence of the taper angle and curvature of the hearth roll on meandering and buckling of the material, and Figure 4. Fig. 5 is a schematic side sectional view of a continuous annealing furnace equipped with a vertical continuous annealing apparatus according to an embodiment of the present invention, and Figs. 6 to 9 are embodiments of the present invention illustrating the combined arrangement of hearth rolls and cylindrical rolls. FIG. 10 is a side view showing a conventional aspect;
FIG. 11 is a front view showing the appearance of wrinkles generated in the band-shaped metal material in the embodiment of FIG. 8, and FIG. 12 is a cross-sectional view (A-A arrow view) of the band-shaped metal material.
Fig. 13 is a front view showing the appearance of wrinkles that occur in a band-shaped metal material in a conventional embodiment, Fig. 14 is a cross-sectional view (BB arrow view) of the band-shaped metal material, and Fig. 15
The figure is a graph showing the proper cylindrical roll position when the hearth roll and cylindrical roll are combined as shown in Fig. 8, and Fig. 16 is a graph showing the proper cylindrical roll position when the hearth roll and cylindrical roll are combined as shown in Fig. 6. The graph showing the position, FIG. 17, is a graph showing the appropriate material tension range for the conventional embodiment and the embodiment of the present invention. 1... Hearth roll, 2... Band-shaped metal material, 3
...Industrial television camera, 4...Heating zone, 5...
Soaking zone, 6...Cylindrical roll, 7...Wrinkle.

Claims (1)

[Scope of Claims] 1. A belt-shaped metal material that is crimped in the vicinity of a hearth roll located in a high-temperature treatment area in a vertical continuous annealing furnace, substantially parallel to the hearth roll axis and wound around the hearth roll. In a continuous annealing apparatus equipped with cylindrical rolls, when the hearth roll and the cylindrical roll attached close to it contact different surfaces of the strip-shaped metal material, their relative positions are defined as lV/DH≦ 3.6 lH/DH≦0.41+0.5DA/DH (where, lV: Vertical distance between hearth roll axis and cylindrical roll axis lH: Horizontal distance between hearth roll axis and cylindrical roll axis DH: Hearth A continuous annealing device characterized in that the outer diameter of the roll is DA: the outer diameter of the cylindrical roll. 2. A cylindrical roll is placed in the vicinity of the hearth roll located in the high-temperature treatment area in the vertical continuous annealing furnace, substantially parallel to the hearth roll axis and crimped onto the band-shaped metal material wound around the hearth roll. In a continuous annealing apparatus equipped with a cylindrical roll, when the hearth roll and the cylindrical roll attached close to it contact the same surface of the strip metal material, their relative positions are lV/DH≦3.6 lH/DH≧0.59 −0.5DA/DH (where, lV: Vertical distance between hearth roll axis and cylindrical roll axis lH: Horizontal distance between hearth roll axis and cylindrical roll axis DH: Outside diameter of hearth roll DA: A continuous annealing device characterized in that the outer diameter of the cylindrical roll is .