JPH07816B2 - Coil cooling convection plate - Google Patents

Description

The present invention relates to a coil cooling convection plate used in an up-end type coil rust-preventing cooling process.

[Prior Art] The coil after batch annealing uses a nitrogen atmosphere,
It is cooled in the inner cover. When the coil is cooled to about 100 ° C, rust does not occur on the coil. Therefore, the coil is taken out from the inner cover and has an involute curved groove or radial groove as shown in FIG. A convection plate (11) for cooling a coil having a cooling air circulation groove (21) that spreads toward is used for transshipment, and the atmosphere is cooled to about 40 ° C.

[Problems to be solved by the invention]

However, when the coil that has been subjected to the above-mentioned treatment is unwound during temper rolling, it often slips between the contact surfaces of the steel strips to cause scratches on the surface of the steel strip on the inner diameter side.

The present invention was devised in view of the above problems, the mechanism of such scratches is investigated and studied, and as a result, the structure of the coil cooling convection plate used in the coil rust prevention cooling process Is to improve.

[Means for solving problems]

The coil cooling convection plate of the present invention used in the up-end type coil anticorrosion cooling process has a main body of the convection plate having a cooling air circulation groove extending from the central portion side toward the peripheral portion, and the coil from the central portion side. In the range up to the position corresponding to the hot point, the diameter gradually increases, and in the range from the position corresponding to the hot point to the outer peripheral portion, the diameter gradually decreases. The basic feature is that it is attached to the coil contact surface side of the main body.

The process leading up to the idea of the constitution of the present invention will be explained below together with the research progress when the mechanism of the occurrence of scratches on the surface of the steel strip as described above was investigated and investigated.

As described above, the scratches on the surface of the steel strip are those caused by the slip between the steel strip contact surfaces of the coil, which can be readily understood by looking at the state, but the cause of the occurrence of the slip, That is, it was unclear why such a slip would occur even in a tightly wound coil.

Various investigations have been made on the cause of such slip generation, but the most direct cause judged from the state of the scratches is the uneven temperature distribution in the coil during the annealing and cooling processes. It was what was decided.

That is, as shown in FIG. 5, the temperature distribution in the radial direction inside the coil at the end of cooling the atmosphere is lowered while showing a gentle descending curve toward the inner diameter side, centering on the so-called hot point. is doing. Further, as shown in FIG. 6, the coil interlayer surface pressure in the radial direction inside the coil is highest at the hot point and becomes lower as it goes away from the hot point, and becomes almost zero in a wide range on the inner diameter side. this is,
This is because the temperature distribution in the coil radial direction is non-uniform as described above, so that the surface pressure between the coil layers decreases due to thermal contraction in the inner diameter side portion.

When the reduction of the surface pressure between the coil layers is remarkable, a fine gap is generated in the inner diameter side portion. FIG. 7 is a graph showing the measurement results when the internal stress was measured at a plurality of points in the coil radial direction by changing the cooling time after the batch annealing. In the inner diameter portion, it is approximately 0 over a considerable range. this is,
There is nothing but a gap in the inner diameter side.

When the mandrel on the temper rolling mill entrance side is inserted into the center of the coil with such a gap, as shown in FIG. 8, due to the weight of the coil (100), the gap (11
0) accumulates at the bottom. Then, when temper rolling starts and unwinding of the coil (100) progresses to the inner diameter side, slipping occurs between the steel strip contact surfaces on the outermost circumference side above the coil (100) so as to reduce the outermost clearance (110). However, the steel strip is pulled out.

If such a condition is the cause of slip occurrence,
This is consistent with the fact that the scratches are concentrated on the surface of the steel strip on the inner diameter side of the coil (100).

Therefore, the inventors of the present invention have devised the present invention in which the coil cooling convection plate used during cooling after annealing has the above-described structure in order to eliminate the temperature gradient generated in the coil during the annealing and cooling processes. It was decided.

[Action]

If the above-mentioned convection plate for cooling the coil, in which the honeycomb-shaped contact plate is attached to the coil contact surface side of the main body, is used in the up-end type coil anticorrosion cooling process after coil annealing, the contact plate hot point opening side The amount of cooling air discharged from the hole is relatively increased as compared with that from the hole on the center side, and the cooling rate on the coil hot point side can be made larger than that on the coil inner diameter side. Therefore, overcooling on the inner diameter side is prevented, and the temperature distribution in the coil after cooling is made uniform.

〔Example〕

 Specific examples of the present invention will be described below.

FIG. 1 is a perspective view showing a partial cutaway of a coil cooling convection plate according to an embodiment of the present invention.

The convection plate has, as its main body (10), a disk body having a large number of grooves (20a) (20b) in the shape of an involute curve formed on its surface as shown in FIGS. The contact plate (30
a) (30b) is installed.

As shown in FIGS. 3 (a) and 3 (b), the diameters of the contact plates (30a) and (30b) gradually increase from the center to the position corresponding to the hot point of the coil. Aperture (40) that becomes larger and its diameter gradually decreases in the range from the position corresponding to the hot point to the outer periphery.
Are provided in a large number, and have a honeycomb shape as a whole.

By changing the diameter of the hole (40) formed on the surface of the contact plates (30a) (30b) in the radial direction around the position corresponding to the hot point, the coil inner diameter side can be cooled. As a result, the flow rate of cooling air to the coil hot point side is reduced and the flow rate of cooling air to the coil hot point side is increased. Therefore, the temperature distribution inside the coil can be made uniform. Further, the control of these cooling rates can be easily performed by changing the opening ratio per unit area of the contact plates (30a) (30b).

In the conventional convection plate, the convection plate body (10) as shown in FIGS. 2 (a) and 2 (b) is used as it is, and when such a convection plate is used to cool the coil to the atmosphere, As shown in FIG. 5, the temperature difference between the coil inner diameter side and the hot point is about 10 to 20 ° C., but when the convection plate of this embodiment is used, the difference is Is about 5 to 7 ° C, which is about half. Therefore, by using the convection plate of this embodiment, the scratches generated during temper rolling can be significantly reduced.

〔The invention's effect〕

As described in detail above, when the coil cooling convection plate of the present invention is used to perform atmospheric cooling after coil annealing, the cooling rate on the coil inner diameter side can be made smaller than that on the coil hot point side. Therefore, the temperature gradient in the radial direction inside the coil is reduced, the inter-layer surface pressure of the coil on the inner diameter side of the coil is increased, and slips are not generated during the unwinding operation of the temper rolling mill. Therefore, the surface of the product is hardly scratched.

[Brief description of drawings]

FIG. 1 is a perspective view showing a whole of a convection plate for cooling a coil according to an embodiment of the present invention by cutting a part thereof and including an internal structure thereof, and FIG. 2 (a) is a convection plate body of the present embodiment. FIG. 3B is a plan view showing the structure, FIG. 3B is a vertical cross-sectional view thereof, FIG. 3A is a plan view showing the structure of the contact plate in this embodiment, and FIG. FIG. 4 is a plan view showing the structure of a conventional coil cooling convection plate, FIG. 5 is a graph showing the temperature distribution in the radial direction inside the coil at the end of atmospheric cooling, and FIG. 6 is the same inside the coil at the end of atmospheric cooling. FIG. 7 is a graph showing the coil inter-layer surface pressure in the radial direction, FIG. 7 is a graph showing the internal stress measurement results in the radial direction inside the coil at the end of atmospheric cooling, and FIG. 8 is a graph showing the temper rolling mill with gaps. It is explanatory drawing which shows the state of the coil attached to the mandrel. In the figure, (10) is a convection plate body, (20a) (20b) (21) is a groove,
(30a) and (30b) are contact plates, and (40) is an opening.

Claims (1)

[Claims] 1. A convection plate for cooling a coil used in an up-end type coil anticorrosion cooling process, comprising a convection plate body having a cooling air circulation groove extending from a central portion side toward a peripheral portion, and a coil contact surface of the body. The diameter is gradually increased in the range from the central portion side to the position corresponding to the hot point of the coil, and the diameter is gradually decreased in the range from the hot point corresponding position to the outer peripheral portion. A convection plate for cooling a coil, which comprises a honeycomb-shaped contact plate provided with openings.