JP6727113B2 - Galvanized steel sheet manufacturing equipment and galvanized steel sheet manufacturing method - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention heats, heat-retains and cools a steel sheet after hot dip galvanizing and gas wiping to produce an alloyed galvanized steel sheet manufacturing equipment and alloying using this manufacturing equipment. The present invention relates to a galvanized steel sheet manufacturing method.

Steel plates (steel strips) are continuously dipped in a molten metal plating bath to perform molten metal plating treatment, and then gas is sprayed on the unsolidified plated surface of the steel plate after immersion to adjust the amount of molten metal deposited. Gas wiping processing is generally performed. In this gas wiping process, gas wiping is performed by disposing gas wiping devices equipped with gas wiping nozzles on both sides of a continuously conveyed steel plate and blowing gas to both sides of the steel plate.

The steel sheet subjected to the gas wiping treatment is conveyed to a galvannealed steel sheet manufacturing facility, where it is subjected to heat treatment, heat treatment (retention treatment) and cooling treatment to manufacture an alloyed galvanized steel sheet.

By the way, the alloyed galvanized steel sheet manufacturing facility is provided with a temperature raising zone, a heat retaining zone, and a cooling zone in order.

Conventional alloyed galvanized steel sheet manufacturing equipment is designed to realize a large number of heat patterns to enable the production of steel sheets of various steel types, and therefore, not only the cooling zone but also the heat retaining zone. Also, a device having a large number of cooling blowers for cooling the steel sheet is generally applied.

Here, in Patent Document 1, production of an alloyed hot-dip galvanized steel sheet equipped with a heat-retaining/cooling furnace that performs at least one of heat retention and cooling for a steel plate that leaves the rapid heating furnace and passes through it. The equipment is disclosed. This manufacturing facility has a heat-retaining area in which the heat-retaining/cooling furnace heat-retains the steel plate at a heat-retaining temperature of 500°C or more and 650°C or less by the heat-retaining means, and an average cooling of the steel plate at 5°C/sec or more with the spray nozzle. It is composed of a cooling region for cooling at a speed, the ratio of the lengths of both regions in the furnace can be set arbitrarily, and the arrangement of the heat retaining region and the cooling region can be set arbitrarily.

JP, 2008-115462, A

According to the manufacturing facility described in Patent Document 1, it is possible to always manufacture an alloyed hot-dip galvanized steel sheet under optimal manufacturing conditions in response to a sudden change in steel type, coating weight, and other external factors. ..

However, as described in FIG. 3 and the like of Patent Document 1, even in the manufacturing equipment disclosed here, a large number of cooling blowers are arranged in the heat retention zone, so it can be denied that the manufacturing cost of the equipment has risen. Absent.

The alloyed galvanized steel sheet manufacturing equipment manufactures steel sheets of various steel types while appropriately selecting the heat retention mode operation and the cooling mode operation. Among these, particularly in the cooling mode operation, the temperature of the steel sheet is lowered to a predetermined temperature by operating a large number of cooling blowers in the heat retaining zone, and the steel sheet is conveyed to the cooling zone.

That is, in the conventional manufacturing facility, a large number of blowers such as a cooling blower that provides cold air to the heat retaining zone during the cooling mode operation, a circulation blower, and an exhaust blower are required.

By the way, in the case of manufacturing equipment that does not require a large number of heat patterns while aiming to manufacture steel sheets of various steel types, it is possible to reduce the manufacturing cost of the equipment by eliminating the need for a large number of cooling blowers in the heat retention zone. It becomes possible to do.

The present invention has been made in view of the problems described above, and while eliminating the cooling blower from the heat retention zone to reduce equipment manufacturing costs, it is possible to realize a large number of heat patterns, and thus manufacture steel sheets of various steel types. It is an object of the present invention to provide an alloyed galvanized steel sheet production facility and an alloyed galvanized steel sheet production method capable of performing the above.

In order to achieve the above-mentioned object, the alloyed galvanized steel sheet manufacturing equipment according to the present invention comprises a temperature raising zone, a heat retaining zone, and a cooling zone in order, and a steel sheet immersed in a plating bath is a temperature raising zone, a heat retaining zone, And a galvanized steel sheet manufacturing facility configured to be conveyed in this order in the cooling zone, wherein the cooling zone is provided with first and second cooling blowers, and the heat retaining zone is located downstream in the steel sheet conveying direction. And a suction duct side position of the first cooling blower is provided with a connecting duct in which the first control valve is interposed, and a blow control side valve of the first cooling blower is provided with a second control valve. And a ventilation duct that leads to the outside, and an opening/closing gate that sucks outside air is provided at a position upstream of the steel plate transport direction in the heat retention zone, and a control unit that operates the equipment in the heat retention mode and the cooling mode is provided. Is what

The alloyed galvanized steel sheet manufacturing equipment of the present invention is provided with two cooling blowers (first and second cooling blowers) in the cooling zone, and between the heat retaining zone and the suction side position of the first cooling blower. The first control valve is provided with a connecting duct, and the blower side of the first cooling blower is provided with a diffusion duct communicating with the outside through a second control valve. It is equipped with an opening/closing gate that sucks outside air at the side position, and by applying the outside air introduced through the opening/closing gate when cooling the steel sheet in the heat retaining zone, it is possible to eliminate the cooling blower in the heat retaining zone. It was possible.

Generally, the amount of heat required for alloying steel sheets and the amount of cooling heat required after alloying are in a proportional relationship. Is born. The present inventors have paid attention to this relationship and have made it possible to eliminate cooling equipment such as a cooling blower from the heat retention zone and quickly move the steel sheet to an appropriate set temperature under a rational equipment configuration. is there. The alloyed galvanized steel sheet manufacturing equipment of the present invention is suitable for manufacturing equipment that does not require a large number of heat patterns, for example.

The alloyed galvanized steel sheet production equipment of the present invention is suitable for production equipment that does not require a large number of heat patterns, for example, but even when a large number of heat patterns are required, by applying the production equipment of the present invention. It is possible to manufacture steel sheets of various steel types.

When the manufacturing equipment of the present invention is operated in the heat retention mode, the first control valve and the second control valve are closed, and cooling air is supplied from the first and second cooling blowers to the cooling zone. The control is executed by the control unit.

During the heat retention mode operation, the temperature of the steel sheet heated in the temperature raising zone is maintained in the heat retention zone, and the cooling air is supplied to the steel sheet from the first and second cooling blowers in the cooling zone. Lower the temperature to a predetermined temperature.

On the other hand, when the manufacturing equipment of the present invention is operated in the cooling mode, the first control valve, the second control valve, and the opening/closing gate are opened, and cooling air is supplied from the first and second cooling blowers to the cooling zone. Is supplied to the heat retention zone via the opening/closing gate, and the control unit executes control to supply the outside air to the heat retention zone.

During the cooling mode operation, by opening the first control valve, the second control valve, and the opening/closing gate, the outside air is taken into the heat retention zone by the suction force of the first cooling blower, and in the heat retention zone. Since the amount of convective heat transfer is increased by the rising airflow, the temperature of the steel sheet in the heat retaining zone can be lowered to a predetermined temperature (improvement of convective heat transfer effect).

That is, since the steel sheet in the heat retaining zone is cooled by the outside air, a cooling blower or the like unique to the heat retaining zone is not necessary when cooling the steel sheet in the heat retaining zone.

In the cooling mode operation, the temperature of the steel sheet heated in the temperature raising zone is lowered to a predetermined temperature by the outside air in the heat retaining zone, and the cooling air is supplied to the steel sheet from the first and second cooling blowers in the cooling zone. To lower the temperature of the steel plate to a predetermined temperature.

In this way, the heat patterns in both the heat retention mode and the cooling mode can be realized only by the switching operation of the first control valve, the second control valve, and the opening/closing gate by the control unit.

According to the manufacturing facility of the present invention, the cooling blower can be completely abolished from the heat retention zone, whereby the facility manufacturing cost can be significantly reduced. Then, while removing the cooling blower from the heat retaining zone in this manner, the heat patterns in both the heat retaining mode and the cooling mode can be obtained only by the switching operation of the first control valve, the second control valve and the opening/closing gate by the control unit. Since it can be realized and can cope with a large number of heat patterns, it is possible to manufacture steel sheets of various steel types.

The present invention also extends to a method for producing an alloyed galvanized steel sheet, which is a method for producing an alloyed galvanized steel sheet using the already described alloyed galvanized steel sheet production equipment. Specifically, when operating in the heat retention mode, the control in which the first control valve and the second control valve are closed and the cooling air is supplied from the first and second cooling blowers to the cooling zone Is operated by the control unit or in the cooling mode, the first control valve, the second control valve, and the opening/closing gate are opened, and the first and second cooling blowers are operated. This is a method for producing an alloyed galvanized steel sheet by using a production facility in which a control unit executes control in which cooling air is supplied to a cooling zone and external air is supplied to a heat retaining zone via an opening/closing gate.

According to the manufacturing method of the present invention, the facility manufacturing cost can be significantly reduced, and both the heat retention mode and the cooling mode can be achieved by only the switching operation of the first control valve, the second control valve and the opening/closing gate by the control unit. The heat pattern can be realized, and a large number of heat patterns can be dealt with.

As can be understood from the above description, according to the alloyed galvanized steel sheet manufacturing equipment and the alloyed galvanized steel sheet manufacturing method of the present invention, two cooling blowers (first and second cooling blowers) are provided in the cooling zone. A first control valve is provided between the heat retaining zone and the suction side position of the first cooling blower, and a second control valve is provided at the blowing side position of the first cooling blower. It is equipped with a diffusion duct that leads to the outside through an opening and closing gate that sucks outside air at a position upstream of the steel plate transport direction in the heat retention zone, and is introduced through the opening and closing gate when cooling the steel plate in the heat retention zone. The applied outside air is applied. With this configuration and control, the cooling blower can be completely eliminated from the heat retaining zone, which can significantly reduce the equipment manufacturing cost. Furthermore, it is possible to realize a large number of heat patterns while eliminating the cooling blower from the heat retaining zone, and thus it is possible to manufacture steel sheets of various steel types.

It is a block diagram of the alloying galvanized steel sheet manufacturing equipment of this invention. It is the figure which showed both the block diagram of the alloying galvanized steel sheet manufacturing equipment, and the heat cycle of heat retention mode. It is the figure which showed the block diagram of the alloyed galvanized steel sheet manufacturing equipment, and the heat cycle of the cooling mode together.

Embodiments of an alloyed galvanized steel sheet manufacturing facility and an alloyed galvanized steel sheet manufacturing method will be described below with reference to the drawings.

(Embodiment of alloyed galvanized steel sheet manufacturing equipment and alloyed galvanized steel sheet manufacturing method)
FIG. 1 is a block diagram of an alloyed galvanized steel sheet manufacturing facility of the present invention. As shown in FIG. 1, the steel plate K is continuously immersed in the molten metal plating bath M in the plating tank B (X1 direction) to be subjected to the molten metal plating treatment, and then pulled up from the plating tank B. Then, gas is sprayed from the gas wiping device W onto the unsolidified plated surface of the steel plate K to adjust the amount of molten metal deposited. The steel sheet K having the amount of molten metal deposited as described above is transported to the galvannealed steel sheet manufacturing facility 100.

The alloyed galvanized steel sheet manufacturing facility 100 includes a temperature rising zone Z1, a heat retaining zone Z2, and a cooling zone Z3 in order, is immersed in the plating bath M, and the amount of molten metal deposited is adjusted by the gas wiping device W. The steel sheet K is configured to be conveyed in the order of the temperature rising zone Z1, the heat retaining zone Z2, and the cooling zone Z3 (conveyance in the heat retaining zone Z2 is in the X2 direction, and conveyance in the cooling zone Z3 is in the X3 direction). ..

The induction heater 10 is disposed in the temperature raising zone Z1, and the steel sheet K conveyed into the manufacturing facility 100 is heated up to a predetermined temperature at once by the induction heater 10.

The heat-retaining zone Z2 is composed of a heat-retaining furnace 20 of a predetermined length. A heat-retaining heater 21 is arranged on the most upstream side of the heat-retaining furnace 20, and an opening/closing gate 22 for sucking outside air is further provided. ..

On the downstream side of the retention heater 21, a hot air supply conduit for providing hot air into the heat retention furnace 20 is arranged with a pilot valve 23 and a combustion blower 24 interposed.

At the most downstream side of the heat retention furnace 20, a hot air exhaust pipe line for arranging a pilot valve 25 and an exhaust blower 26 to exhaust hot air in the heat retention furnace 20 is arranged.

The cooling zone Z3 is composed of a cooling furnace 30 of a predetermined length, a first cooling blower 32 is arranged at an intermediate position of the cooling furnace 30 via a cooling blower control valve 31, and a second cooling blower 33 is further provided. Is provided.

Further, a connection duct 40 in which the first control valve 41 is interposed is provided between a position on the downstream side in the steel plate transport direction in the heat retention zone Z2 and a position on the suction side of the first cooling blower 32.

Further, a diffusion duct 50 communicating with the outside through a second control valve 51 is provided at a position on the blow-out side of the first cooling blower 32.

Further, the manufacturing equipment 100 includes a control unit 60, and the control unit 60 operates and stops the induction heater 10, operates and stops the combustion blower 24 and the exhaust blower 26, the first cooling blower 32, and the second cooling blower 32. In addition to the operation and stop of the cooling blower 33, switching control of the first control valve 41, the second control valve 51, the opening/closing gate 22, and the like are executed.

In the manufacturing facility 100, as will be described later, only the switching operation of the first control valve 41, the second control valve 51, and the opening/closing gate 22 by the control unit 60 realizes heat patterns in both the heat retention mode and the cooling mode. To do.

As described above, since the manufacturing facility 100 does not include any cooling blower in the heat retaining zone Z2, the facility manufacturing cost is significantly higher than that of the conventional manufacturing facility including a large number of cooling blowers in the heat retaining zone. It will be cheaper.

Next, with reference to FIGS. 2 and 3, a control mode and a heat cycle in the heat retention mode and the cooling mode of the manufacturing equipment will be described, and thus the alloyed galvanized steel sheet manufacturing method of the present invention will be described.

FIG. 2 is a diagram showing both the configuration diagram of the galvannealed steel sheet manufacturing equipment and the heat cycle in the heat retention mode.

When operating in the heat retention mode, the first control valve 41 and the second control valve 51 are closed, and cooling air is supplied from the first cooling blower 32 and the second cooling blower 33 to the cooling zone Z3. The control performed by the control unit 60 is performed.

During the heat retention mode operation, first, the temperature of the steel sheet K heated to 550° C. in the temperature elevation zone Z1 is maintained in the heat retention zone Z2, and the first cooling blower 32 and the second cooling blower 32 are cooled in the cooling zone Z3. Cooling air is supplied from the cooling blower 33 to the steel plate K to lower the temperature of the steel plate K to a predetermined temperature (300° C.).

On the other hand, FIG. 3 is a diagram showing both a configuration diagram of an alloyed galvanized steel sheet manufacturing facility and a heat cycle in a cooling mode.

When operating in the cooling mode, the first control valve 41, the second control valve 51, and the opening/closing gate 22 are all opened, and the cooling air is cooled from the first cooling blower 32 and the second cooling blower 33. The control unit 60 executes control to supply the zone Z3 and the outside air to the heat retention zone Z2 via the opening/closing gate 22 (introduction direction of the outside air: Z1 direction).

During the cooling mode operation, by opening the first control valve 41, the second control valve 51, and the opening/closing gate 22, outside air is taken into the heat retention zone Z2 by the suction force of the first cooling blower 32, among others. It will be.

In the heat retention zone Z2, the temperature of the steel sheet K heated to 520° C. in the temperature raising zone Z1 is increased to a predetermined temperature (460° C. in the cooling mode 1, because the amount of convective heat transfer is increased by the ascending airflow caused by the introduction of outside air. In cooling mode 2, it can be lowered to 435°C).

In both the cooling mode 1 and the cooling mode 2, the cooling air is supplied to the steel sheet K from the first cooling blower 32 and the second cooling blower 33 in the cooling zone Z3, so that the temperature of the steel sheet K becomes a predetermined temperature (300°C). ).

As described above, when cooling the steel sheet K in the heat retaining zone Z2, the first control valve 41, the second control valve 51, and the open/close control by the control unit 60 are performed without using any cooling blower unique to the heat retaining zone Z2. Heat patterns in both the heat retention mode and the cooling mode are realized only by the switching operation of the gate 22.

According to the manufacturing equipment 100 and the manufacturing method shown in the drawing, the cooling blower can be completely abolished from the heat retention zone Z2, whereby the equipment manufacturing cost can be significantly reduced. While the cooling blower is removed from the heat retention zone Z2 in this manner, the heat retention mode and the cooling mode are changed only by the switching operation of the first control valve 41, the second control valve 51 and the opening/closing gate 22 by the control unit 60. Since both heat patterns can be realized and a large number of heat patterns can be supported, it is possible to manufacture steel sheets of various steel types.

The manufacturing facility 100 is suitable for a manufacturing facility that does not require a large number of heat patterns, but even when a large number of heat patterns are required, by applying the manufacturing facility 100, it is possible to manufacture steel sheets of various steel types. It is possible.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like within the scope not departing from the gist of the present invention. However, they are included in the present invention.

DESCRIPTION OF SYMBOLS 10... Induction heater, 20... Retaining furnace, 21... Retention heater, 22... Opening/closing gate, 24... Combustion blower, 26... Exhaust blower, 30... Cooling furnace, 31... Cooling blower control valve, 32... First cooling Blower, 33... Second cooling blower, 40... Connection duct, 41... First control valve, 50... Dispersion duct, 51... Second control valve, 60... Control part, 100... Alloyed galvanized steel sheet manufacturing facility (Manufacturing equipment), Z1... Temperature rising zone, Z2... Heat retention zone, Z3... Cooling zone, K... Steel plate, B... Plating tank, M... Plating bath, W... Gas wiping device

Claims (4)

Manufacture of an alloyed zinc-plated steel sheet having a temperature raising zone, a heat retaining zone, and a cooling zone in that order, and a steel sheet immersed in a plating bath is conveyed in the order of the temperature raising zone, the heat retaining zone, and the cooling zone. Equipment,
First and second cooling blowers are arranged in the cooling zone,
A connection duct in which a first control valve is interposed is provided between a position on the downstream side in the steel plate transport direction in the heat retention zone and a position on the suction side of the first cooling blower,
At the position on the blow-out side of the first cooling blower, there is provided a diffusion duct communicating to the outside with the second control valve interposed.
An opening/closing gate for sucking outside air is provided at a position on the upstream side in the steel plate transport direction in the heat retention zone,
An alloyed galvanized steel sheet manufacturing facility equipped with a control unit that operates inside the facility in heat retention mode and cooling mode. When operating in the heat retention mode, the control unit controls the first control valve and the second control valve to be closed and the cooling air is supplied to the cooling zone from the first and second cooling blowers. The galvanized steel sheet manufacturing equipment according to claim 1, which is carried out. When operating in the cooling mode, the first control valve, the second control valve, and the opening/closing gate are opened, cooling air is supplied to the cooling zone from the first and second cooling blowers, and the cooling air is supplied via the opening/closing gate. The alloyed galvanized steel sheet manufacturing equipment according to claim 1, wherein the control unit executes control to supply the outside air to the heat retaining zone. A method for producing an alloyed galvanized steel sheet, which comprises producing an alloyed galvanized steel sheet using the alloyed galvanized steel sheet production equipment according to claim 2.

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