JPS5891131A - Annealing device for cold-rolled coil - Google Patents

Abstract

PURPOSE:To shorten annealing time by flowing atmospheric gas for heating a cooling coil in the order of the inside of the coil, a convection plate, and the outside of the coil, and providing a gas diffuser device in the center hole of each convection plate and making dispersion of the atmospheric gas uniform to the upper and to the outside of the coil. CONSTITUTION:Atmospheric gas is heated by the combustion heat of the burner 21 of an indirect heat exchanger 20 provided at the outside of a furnace 1. The atmospheric gas is fed to the heat exchanger 20 by a circulating fan 22, and the gas is heated up to prescribed temperature and then fed into the furnace 1 through a circulation passage 23. The atmospheric gas flows through the space part 24 inside of the cooling coil 3 in the furnace 1 and is dispersed from the inside to the outside of the coil through an orifice as a gas diffuser device provided in the convection plate 6. Simultaneously, heat is conducted to the coil 3, and the gas is sucked downward outside of the coil, and recirculated by the circulating fan 22 to the heat exchanger 20, where it is reheated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cold-rolled coil annealing apparatus, and more particularly to a cold-rolled coil annealing apparatus in which the flow direction of atmospheric gas for heating the cold-rolled coil is changed.

Cold rolled coil, i.e. 1 obtained by cold rolling; The coil has deteriorated in C processability due to roughening.

Generally, this is annealed to soften the steel and improve workability. The soft annealing method for cold-rolled coils includes two methods: a method in which the cold-rolled coil from the cold rolling machine is continuously sent to the annealing process, and then it is continuously annealed; There is a method in which the coil is annealed in batches. When performing the batch method, cold rolled coils are stacked in several stages (8 to 4 stages) on the hearth, an inner cover is then placed on the outer cover, and the inner cover is heated directly or indirectly using a burner attached to the outer cover (radiant tube). conveys heat to. The heat transferred to the inner cover heats the internal atmospheric gas, and this heated atmospheric gas flows upward on the outer coil wlJ side, partially from the top and partially from the outer circumferential side of the coil to inside the coil wjJ14iI. It is then sucked downward through the space at the center of the coil and circulated.

FIG. 1 shows a schematic cross-sectional view of a conventional patch-type annealing furnace. In FIG. ) is composed of 4 inch covers, 6 pieces, and 6 pieces. A convection plate 6 is provided between the coils, and the atmospheric gas circulated by a circulation fan 7 provided in the hearth 2 is first directed upward through a lodging space 8 formed by the outer circumferential side of the coil and the inner cover. A part of the current flows from the top of the coil to the space 9 at the center of the coil, but most of it flows from the convection plate 60 to the inside of the coil 1.
Flows towards ilIII. In this way, the heated atmosphere gas flows from the outer side of the coil toward the inner circumferential side of the coil. An orifice plate 10 is often provided at the top of the coil to restrict the flow of atmospheric gas from the top of the coil. The symbol "Mo" indicates a motor for a circulation fan.

By the way, in such a conventional device, since the heat source is the burner 11 provided on the outer cover, heat is transferred to the coil through the outer cover and the inner cover.

It is carried out in one line to the atmosphere gas and then to the coil. However, the gas velocity (V) of the atmospheric gas flowing through the convection plate is not uniform in the radial direction in its horizontal cross section, as schematically shown in FIG. 2, and has very large variations. In Figure 2, the gas velocity in each direction is plotted on circular coordinates, and the graph is close to a circle, indicating that the gas velocity in each direction is uniform. Such a gas velocity distribution is different for each convection plate, and in particular, if the outer diameter of the coil differs, the pressure loss in the outer side direction changes, so the flow velocity to the convection plate further changes for each stage. Furthermore, if the center of the coil is shifted when stacking the coils, the pressure resistance changes in the circular direction, which also causes variations in the gas velocity in the radial direction. Therefore, uniform heating of the entire coil was not achieved, and problems such as heating and staining occurred in some overheated areas occurred.

By the way, as mentioned above, in the conventional device shown in FIG. 1, heat is transmitted from the burner provided on the outer cover to the inner cover by direct flame or indirect heating (radiant chain). On the other hand, inside the inner cover, the atmospheric gas
As shown by the arrows in the figure, it circulates and is heated by the cylinder cupper, then heats the convection plate by convection, and the heat is transmitted to the coil through this convection plate.

However, in such conventional devices, the atmospheric gas is mainly heated by convection with the inner cover, but as mentioned above, the gas flow inside the inner cover changes depending on the structure of the convection plate, coil poles, etc. There will be variations in temperature. Generally, the upper part of the coil tends to be madder. In addition, since it is not possible to control the temperature V of the atmospheric gas, it is not possible to perform strict temperature mW processing depending on the material of the cold-rolled coil. In addition, heat is transferred from the outer circumferential direction of the coil through the inner cover and the like, which may cause overheating and seizure, and in particular, the top or upper coil of the annealed coil may suffer from seizure or defective products due to uneven heat.

In order to eliminate the drawbacks of the conventional apparatus, the present inventor has previously completed an apparatus for annealing cold-rolled coils using an indirect heat exchange method using atmospheric gas. (% Application No. 56-152024) The present invention aims to further improve such a novel cold-rolled coil annealing device, and the present invention is not limited to such a device; This book attempts to provide a cold-rolled coil annealing device that can produce excellent young fruit even when used with conventional devices.

Here, the present invention includes; a hearth for stacking cold-rolled coils; an inner cover disposed on the hearth so as to surround the stacked cold-rolled coils with a convection plate interposed therebetween; An outer cover disposed on the Ka hearth so as to surround the inner cover, and a heating atmosphere gas for heating the cold-rolled coil within the inner cover are supplied upward in a central space of the cold-rolled coil within the inner cover. At the same time, in the outer periphery of the cooling coil, there is an atmospheric gas circulation device that sucks the atmospheric gas downward, and a heating atmospheric gas flowing upward through the air barrier section marked # is directed along the convection plate 9 from inside the coil to the outer peripheral side of the coil. and a gas defusing device provided on the convection plate to disperse the gas. This is a cold rolled coil annealing device.

As described above, according to the present invention, the atmospheric gas for heating the cold-rolled coil flows from the inner part of the coil, to the convection plate, and then to the outer circumferential side of the coil, contrary to the conventional method. A differential user device is installed in the upper direction of the atmosphere gas and outside the coil W! Because the dispersion into 8iI411 was made uniform,
Heating of the coil can now be done uniformly, quickly and efficiently not only in the horizontal direction but also in the vertical direction. Furthermore, if a method is adopted in which the atmospheric gas for heating the cold-rolled coil is heated in a heat exchanger provided outside, any required temperature can be secured and the temperature can also be accurately controlled. It is also possible to increase the difference between the atmospheric gas and the coil heating temperature, thereby making it possible to shorten the annealing time.

The gas differential user device according to the present invention is particularly limited as long as the gas flow from the inner coil side to the outer circumferential side of the coil is as uniform as possible over the entire convection plate of each stage. Although not required, it may generally consist of an orifice provided in the center hole of the convection plate. As will be readily understood by those skilled in the art, by suitably changing the shape of the orifices at each stage, each convection plate can be supplied with an equal gas velocity of atmospheric gas, thus increasing the gas flow across each convection plate. can be made uniform. Further, as a modification example, this gas differential user device may be constructed by sequentially changing the size of the center hole of each RR plate. In any case, any suitable shape can be used as long as it can supply atmospheric gas at the same gas velocity to each convection plate. Note that the structure of the convection plate itself may be a conventional one.

The atmospheric gas circulation device is composed of a fan and its driving mechanism, but in the present invention, the flow direction of the atmospheric gas is reversed compared to the conventional device, so the conventional device is used. If so, simply reverse the mounting position of the fan.

The present invention will be further explained with reference to the drawings.

In the following explanation, the present invention will be explained using a device that employs an external indirect heating method for atmospheric gas, but the present invention is not necessarily limited thereto, and it is easily applicable to conventional devices in general. be understood.

FIG. 8 is a schematic cross-sectional view of the device according to the invention.

In the figure, the same members as in FIG. 1 are denoted by the same reference numerals. An indirect heat exchanger 20 provided outside the furnace is provided with a burner 21, and atmospheric gas (generally a gas such as N, -?H, etc.) is heated by the combustion heat generated by the burner. The atmospheric gas is sent to the heat exchanger for heating the atmospheric gas by the circulation fan 22 and heated to a predetermined temperature, and then sent into the furnace through the atmospheric gas circulation path 28 and flows through the space 24 at the center of the detection coil 8. A gas differential user device installed in this space 24, in the example shown, an orifice 25 provided in the convection plate 6 disperses the flow from the coil I@9411 to the outer circumferential side of the coil, during which heat is transferred to the coil and the outer circumferential side of the coil is dispersed. The air is sucked downward and recirculated to the heat exchanger 20 by the circulation fan 22, where it is reheated. The flow direction of the atmospheric gas is indicated by an arrow in the figure. FIG. 4 is a partially enlarged view of the convection plate 6 and orifice 25 that constitute the gas differential user device.

The combustion exhaust gas 26 is sent from the heat exchanger 20 to the loam-like conduit R127 inside the outer cover, and is then discharged after heat exchange with the fuel combustion air 28 and the newly supplied atmospheric gas 29 through the respective heat exchangers 80 and 81. be done. The fuel from the fuel supply path 82 may be preheated by the fuel gVI exhaust gas, if necessary.

Figure 1 is due to non-invention. The gas velocity of the atmospheric gas in the radial direction of the cross section of the convection plate is plotted on a circular cone.As can be seen from the fact that according to the present invention, a nearly circular graph is obtained for each convection plate, It can be seen that a substantially uniform gas flow can be obtained in either direction.

As described above, according to the present invention, the atmospheric gas can be uniformly released not only in the horizontal direction but also in the vertical direction, so that heat transfer to the coil can be increased. For example, the relationship between the heating time and the coldest point temperature when the ambient gas temperature is supplied at 750 to 780° C. is shown graphically in one figure. The heated curved edges according to the invention are represented by open circles and solid lines. The illustrated data is the 8th
This was obtained by stacking cooling coils in four stages and heating them using the equipment shown in the figure. This is the point shown. In the figure, reference numeral 41 indicates a cold-rolled coil.

42 is a convection plate.

As can be seen from the illustrated results, when the intended heating temperature of the coil is 680° C., according to the present invention, the heating time during annealing can be shortened by 4 hours in all the illustrated examples compared to the conventional example. A conventional example is an apparatus shown in FIG.

Historically, since the atmospheric gas temperature was controlled to be constant, there was no burning due to overheating, and the quality could be improved.

[Brief explanation of drawings]

Fig. 1 Fi is a schematic cross-sectional view of a conventional cold rolled coil annealing device; Fig. 2 is a graph schematically plotting the gas velocity of the atmospheric gas in the radial direction of the convection plate lr surface using the conventional device; A schematic cross-sectional view of the cold-rolled coil annealing apparatus according to the present invention; FIG. 4 is a partially enlarged view of the convection plate and orifice shown in factor 8; FIG. A graph schematically plotting the gas velocity of atmospheric gas; Figure 6 is a graph showing the relationship between cold spot temperature and time; and Figure 7 is a schematic side view of the coil showing the measurement point of the coldest spot temperature. be. 1: Annealing furnace 6: Convection plate 2: Hearth 21: Burner 8: Cold-rolled coil 22: Fan 4: Inner cover 28: Atmospheric gas circulation path 5: Outer cover 25 Niorifice fountain / Zuo 2 Zuizumi 5 Figure

Claims (1)

[Claims] A hearth on which cold-rolled coils are stacked, an inner cover disposed on the hearth so as to surround the stacked cold-rolled coils with a convection plate in between, and an inner cover disposed on the hearth so as to further surround the inner cover. A heating atmosphere gas for heating the chilled outer cover and the cold-rolled coil in the inner cover is supplied upward to the central space of the cold-rolled coil in the inner cover, and also to the outside of the cold-rolled coil.
In I4@, there is an atmospheric gas circulation device that sucks the atmospheric gas downward, and a heated atmospheric gas circulating device that sucks the atmospheric gas upward through the space.
A cold-rolled coil annealing device comprising: a gas dephasor device provided on the convection plate, which disperses gas from the inner periphery of the coil toward the outer periphery of the coil along the convection plate.