JPS6047351B2 - Rust prevention control method and equipment for annealed coiled steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rust prevention control method and apparatus for annealed coiled steel strip.

Generally, after the annealing process has been completed, the coiled steel strip is cooled down to around 100-odd degrees Celsius in the annealing furnace, and then the retort (annealing cover) is removed and taken out to be further cooled to a temperature close to room temperature. They are temporarily placed one by one or stacked in several tiers on the waiting floor.

After annealing, the coiled steel strip is subjected to temper rolling in a skin bath mill, but when the coiling temperature in this skin bath process is high (that is, the cooling in the atmosphere on the waiting floor is not sufficient), the skin bath When rolled, age hardening of the steel strip is accelerated, and on the other hand, there is a concern that the coiled strip steel may be locally overcooled during atmospheric cooling, resulting in problems due to condensation when the temperature becomes lower than the dew point of the atmosphere. . Conventionally, in order to achieve cooling that prevents such interference and does not cause the harmful effects of aging, a method is generally used in which expensive air conditioning equipment is used to cool the product in an atmosphere with low humidity, usually less than 35%. It is used. However, if air-conditioning equipment is used to prevent the effects of aging and aging, the depreciation and operating costs will cost more than 100 yen per ton of steel strip, and this will cost more than just the storage and management of the steel strip. When the strip steel is cooled immediately after annealing, a large amount of dehumidifying cooling medium is required, which further increases costs. This invention advantageously solves the above-mentioned problems by using the air drawn directly from the atmosphere to cool the coiled steel strip immediately after being extracted from the annealing furnace, and by reducing the temperature of the coiled steel strip. Before the temperature reaches the risk of rusting, the cooling air is heated to a temperature higher than the atmospheric temperature, and then the smoke is heated to a temperature higher than that of the atmosphere, thereby avoiding local cooling where there is a risk of corrosion. By further cooling the coiled steel strip i and storing it in this elevated temperature atmospheric atmosphere, it is possible to advantageously prevent cracking without requiring significant expense, while subjecting it to skin bath rolling to cause aging changes. It is possible to cool and control the coiled steel strip to a temperature of no.

According to the present invention, the rust prevention management cost can be reduced to about one-tenth of that in the case of using air conditioning equipment.

Figure 1 shows the external appearance and cross-sectional view of a coiled steel strip 1 that should be controlled for rust prevention. In the figure, 2 is the middle of the coil, 3 is the hollow hole,
4 and 5 are inner and outer circumferential edges, 6 and 7 are both end surfaces, and 8 and 9 are inner and outer circumferential surfaces.

This coiled steel strip 1 is cooled in the annealing furnace to a temperature of over 100 degrees, and then left to cool in the atmosphere. At this time, the temperature of the middle 2 reaches S Before the temperature reaches 70°C, both the inner and outer peripheral edges 4, 5 are already below 70°C, and if left to cool, rust will occur.

In this invention, before the inner and outer circumferential edges 4 and 5 of the coiled steel strip 1 approach the atmospheric temperature at which there is a high risk of rusting at temperatures below 70'C, the cooking air flow is passed through the hollow hole 3 of the coiled steel strip 1. The cooling is controlled so that the temperature does not drop below the risk of rusting in any part of the coiled steel strip.

2) As shown in Fig. 2, a waiting floor 1 of coiled steel strip 1
An air supply means 12, 12'', which opens upward on the air supply pipe 13 and is connected to a fan 11 that sucks the atmosphere, is arranged branching from the air pipe 13, and a central hole 14 that is aligned with the opening of the air supply means 12, 12'' is provided. A bottom plate 16 (FIG. 3) having a plurality of spacers 15 arranged radially around it is placed on the standby floor 10, and a coiled steel strip 1 is placed on the standby floor 10, with its center hole 3 being located at the center of the bottom plate 16. hole 1
4, and in many cases, as shown in FIG. The coiled steel strips 1 are stacked in several stages with seat plates 20 (FIG. 4) arranged therebetween, and similarly radial spacers 21 are placed on the end face 7 of the coiled steel strip 1 in the uppermost stage. By overlapping the arranged blind cover plates 22 (FIG. 5), each coiled steel strip is inserted between the center holes of the bottom plate 16 and the seat plate 20 and between the spacers 15, 17, 18 and 21 of the cover plate 22. A ventilation path is formed along both end surfaces of 1.

In this way, the bottom plate 16, the lid plate 22 and the sometimes used seat plate 20 serve as ventilation means.

The annealed coiled steel strip transported to the waiting floor 10 in this manner is first exposed to cooling in the atmosphere at the temperature at which it is taken out from the annealing furnace. When the coiled steel strip 1 is operated, the airflow ejected from the air supply means 12, 12'' passes through the ventilation means 16, 20, 22, and the inner circumferential surface 9, both end surfaces 6,
Forced cooling can be applied to 7.

For selective use of the air supply means 12, 12'', a damper 23, 23'' may be provided at each outlet.

By the above-mentioned cooling or forced cooling, the ventilation can be switched to a gentle temperature before the temperature of the inner and outer peripheral edges 4 and 5 of the coiled steel strip 1, which decreases in temperature before the middle 2, reaches the risk temperature for rusting. Each air supply means 12, 12' has a heater 24.
, 24'' is built-in.

Under this configuration, cooling control as shown in FIG. 6 can be applied to the coiled steel strip 1.

In FIG. 6, a broken line α indicates the estimated temperature inside the coil, that is, the middle 2, a solid line β indicates the measured temperature at the inner and outer peripheral edges 4 and 5, and a chain line γ indicates the air supply temperature. The annealing cover of the coiled steel strip 1 is removed when the temperature drops to over 100 degrees Celsius, and this point is indicated by B in the diagram. As shown by , the coiled steel strip 1 has almost uniform Al°C in all parts, and after being carried onto the waiting floor 10 in this state, ? Start blowing cold air at this point. At this time, the blowing temperature is approximately S equal to the ambient temperature ~°C. The temperature of the outer peripheral edges 4 and 5 of the coiled steel strip 1 decreases before the middle 2, and if the above cooling is continued until the temperature drops below A4°C, the temperature decrease of the coil middle 2 becomes as indicated by the thin broken line α''. On the other hand, the inner and outer peripheral edge temperatures are at the rusting danger temperature A3 as indicated by the thin solid line β''.
℃, and even though the middle 2, that is, the coiled steel strip 1, is at a temperature not suitable for skin bath rolling, it locally enters the danger region of rusting. Therefore, in this invention, at A4°C, which is slightly higher than the rusting danger temperature A3°C, the inner and outer peripheral edges 4 are
. ΔH''
can be reduced to

Rust on coiled steel strips can usually be completely prevented if the temperature is about S10°C higher than room temperature, so the temperature at point A3 is room temperature +1.
It is sufficient to keep it at around 0°C, and the eight point temperature is room temperature + 20'C.
This is usually sufficient.

In this way, local supercooling in the vicinity of the outer peripheral edges 4 and 5 of the entire surface of the coiled steel strip 1, which cools quickly, is prevented by the dielectric flow according to the present invention. At the time of starting the flow, the coiled steel strip 1 is cooled by the heat flow from the middle part 2, which is still slightly higher than the airflow temperature, to the upper and lower end surfaces 7, 6 and the inner and outer circumferential surfaces 9, 8, and the coiled steel strip 1 is heated to a uniform temperature. Since the entire body is cooled to a temperature higher than room temperature, the present invention can be smoothly applied to a skin bath process without fear of rusting.

Further, according to the present invention, a simple device that does not require large-scale equipment and greatly reduces depreciation and costs can be used to
It is possible to reliably cool the coiled steel strip without causing local overcooling.

[Brief explanation of drawings]

Figure 1A, C] The perspective view and Figure 6 show the cooling characteristic curves. 1... Coiled steel strip, 2... Middle,
3... Center hole, 4, 5... Inner, outer peripheral edge, 6, 7... Both end surfaces, 12, 12゛...
Air supply means, 14, 15, 19, 17, 21...
Ventilation means.

Claims (1)

[Claims] 1. When the coiled steel strip that has undergone annealing is left on standby in the atmosphere, the temperature at the inner and outer peripheral edges of the coiled steel strip extracted from the annealing furnace drops close to the risk temperature for rusting. , the air is sucked directly from the atmosphere by a fan, and is heated to a temperature slightly higher than the atmospheric temperature, and then flows through a hollow hole in a coiled steel strip along both end surfaces thereof. Rust prevention management method for annealed coiled steel strip. 2 An air supply means that opens upward on the waiting floor of the coiled steel strip and is connected to a fan that sucks the atmosphere, and a coiled steel strip that is carried up to the upper end with the center hole concentric with this air supply means. It is characterized by comprising a ventilation means for guiding a flow of air from a central hole along both end faces, and that the air supply means has a built-in heating means for raising the temperature of the sucked atmosphere to a temperature slightly higher than the atmospheric temperature. Rust prevention control device for annealed coiled steel strip.