JPH0645875B2 - Continuous vacuum deposition equipment for strip steel - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous vacuum deposition apparatus for strip steel, and more particularly to the above apparatus connected to a continuous annealing furnace for strip steel, zinc,
The present invention relates to an apparatus suitable for continuously vacuum-depositing aluminum, ceramics, etc. on a steel strip.

[Prior Art] A conventional zinc plating line is generally a line in which a coil cold-rolled by a cold rolling mill is rewound by a rewinding machine, passed through a looper, and melt-plated through an annealing reduction furnace. It was the target.

This molten zinc plating line has been improved, and a vacuum deposition zinc plating line in which a vacuum sealing device and a vapor deposition device are provided on the rear surface of the annealing and reducing furnace of the molten zinc plating line via an inert gas replacement chamber has also been industrialized. There is. As described above, conventionally, there is no facility that directly leads to vacuum deposition zinc plating from a continuous annealing furnace, and it is common to pass an annealing reduction furnace used in a molten zinc plating line.

[Problems to be solved by the invention]

However, the above-mentioned vacuum deposition zinc plating line that passes the annealing reduction furnace has a slow stripping speed, while the strip steel is suitable for vacuum deposition zinc plating unless the annealing reduction furnace with a slow stripping rate is passed. Since the surface properties of the strip steel cannot be obtained, the productivity is low and the cost is high.

In order to solve this, it may be considered to connect a vacuum deposition zinc plating line to a continuous annealing line having a high sheet passing speed, but this connection technique has the following problems.

(1) The continuous annealing furnace for strip steel is generally targeted at low carbon steel, and is composed of heating zone, soaking zone, slow cooling zone, quenching zone, overaging zone and final cooling zone, and the newly developed ultra low carbon Steel does not require a soaking zone, a slow cooling zone, a quenching zone and an overaging zone, but the furnace atmosphere has a hydrogen concentration of 2 to 3 in each zone.
%, The nitrogen concentration is 98 to 97%, and the dew point is about -20 ° C.
The iron oxide on the surface of the strip steel annealed in the atmosphere of the furnace is not sufficiently reduced by hydrogen gas, and when vacuum vapor deposition zinc plating is applied, the adhesion between zinc and the strip steel is not sufficient, There was a problem of zinc peeling.

(2) The strip steel continuous annealing furnace has an extremely large furnace capacity,
When the amount of hydrogen gas used as an atmosphere gas is large and the hydrogen gas concentration is 10% or more, the unit consumption of hydrogen gas increases and the cost increases. Further, since hydrogen gas has a risk of explosion, the atmosphere gas in the furnace is usually operated at a concentration of 2 to 3% within the explosion limit of hydrogen gas.
If you operate at a hydrogen gas concentration exceeding the explosion limit and air (oxygen) enters and explodes, the capacity of the furnace is large, so
The damage to the equipment becomes immense. Therefore, the hydrogen gas concentration cannot be made higher than the explosion limit.

The present invention solves the above problems and proposes a continuous vacuum vapor deposition plating apparatus which has high productivity and can perform zinc plating or the like at low cost.

[Means for solving problems]

The present invention replaces the above problem with a technique in which a vacuum deposition zinc plating equipment is connected to the exit of a conventional annealing reduction furnace, and a reduction zone for reducing the strip steel surface is provided at the exit of the continuous annealing furnace for strip steel. By additionally installing it, it is possible to solve the problem by connecting a vacuum deposition zinc plating equipment to a continuous annealing furnace.

That is, the present invention provides a reducing zone for reducing and removing the oxide film on the surface of the strip at the outlet of the continuous annealing furnace for the strip, and an inert gas through a cooling device for cooling the strip by a gas jet on the rear surface of the reducing zone. The present invention relates to a continuous vacuum vapor deposition apparatus for strip steel, which is provided with a substitution chamber and further provided with a plurality of vacuum sealing devices and at least one vacuum vapor deposition device on the rear surface of the inert gas substitution chamber.

The device of the present invention can be applied not only to zinc plating but also to vacuum deposition of aluminum, ceramics, or the like.

[Action]

In the present invention, the oxide film on the surface of the annealed strip steel is reduced and removed by the reduction zone provided at the outlet of the continuous annealing furnace for strip steel.

Further, in the present invention, a cooling device for cooling the strip steel by the gas jet is provided on the rear surface of the reduction zone, and the strip steel temperature is adjusted here to a temperature suitable for vacuum deposition.

Since this cooling device may be operated in a weak reducing atmosphere as described later, an inert gas replacement chamber is provided on the rear surface of this cooling device.

Then, zinc, aluminum, ceramics or the like is vapor-deposited on one side or both sides of the steel strip by at least one vacuum vapor deposition apparatus provided on the rear surface of the inert gas substitution chamber through a plurality of vacuum sealing devices.

In the case of the present invention, the reduction zone is operated in a high-concentration hydrogen atmosphere above the explosion limit. Thereby, the iron oxide on the surface of the strip steel is sufficiently reduced, the adhesion between the plating metal and the strip steel is improved, and a plating product without peeling can be obtained. In addition, even if air is mixed in the reduction zone and an explosion occurs, damage to the equipment can be suppressed to a minimum.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

As shown in the figure, the apparatus of the present invention is provided with an outlet for the annealed strip steel 2'above the final cooling zone 1 of the continuous annealing furnace, and the furnace atmosphere gas seal roll 3'and the deflector roll 1 are provided at this outlet.
5, 16 and the reduction zone 18 via the sealing device 17 _1.
Are connected.

The rear surface of the reducing zone 18 (the exit side of the reducing already steel strip) is sealing device 17 ₂ is provided, the cooling device 19 of the exit side reduction already steel strip is connected to the rear surface of the sealing device 17 _2. Via a sealing device 17 ₃ to the rear surface of the outlet side cooling apparatus 19 is provided an inert gas substitution chamber 20 connects the vacuum seal device 22 further through the sealing device 17 _4, the first deposition chamber 23 in the rear surface, The second vapor deposition chamber 24 is connected in this order.

A vacuum sealing device 22, a cooling device 25, an alloying treatment furnace 27, and a cooling device 28 are connected to the exit side of the vapor-deposited steel strip in the second vapor deposition chamber 24. On the outlet side of this cooling device 28, a water cooling tank 4, a squeeze roll 5, a dryer 6, a tension bridle 8, an outlet looper 9, a tension bridle 10, which are provided on the outlet side of a conventional continuous annealing furnace, Skin pass mill 11, tension bridle 12, shear 1
3, the coiler 14 is connected.

Next, the operation of the device of the present invention will be described.

From the upper part of the final pass of the final cooling zone 1 of the existing continuous annealing furnace, the annealed strip steel 2'is guided to the sealing device 3 ', and passed through the deflector rolls 15 and 16 and the sealing device 17 ₁ to the reduction zone 18'.
Then, iron oxide on the surface of the steel strip is reduced and removed by a jet of hot hydrogen gas, and the active surface properties suitable for vapor deposition plating are adjusted.

Then, lead to the sealing device 17 _2, the outlet side cooling apparatus 19,
Sealing device 17 _3, inert gas replacement chamber 20, the sealing device 17 _4, deflector roll 21, via a vacuum seal device 22, on one side of the strip 2 'by the first vapor deposition chamber 23, subjected to evaporation plated, second Vapor deposition is applied to the remaining surface in the vapor deposition chamber 24.

Thereafter, the vacuum sealing apparatus 22, cooling apparatus 25, via the sealing device 17 ₅ and deflector rolls 26, alloying treatment furnace 27 is guided to the cooling apparatus 28, further the deflector roll 29,30,31,32,33,34 After that, it is introduced into the water cooling tank 4, and then the existing squeeze roll 5 to shear 13
After that, the coiler 14 is wound up.

In addition, when it is not plated, the strip steel 2 that has been passed through the final cooling zone 1 only through the heating zone, soaking zone, quenching zone and overaging zone (not shown) of the existing continuous annealing furnace ,
As usual, the seal roll 3, the water cooling tank 4, the squeezing roll 5, the dryer 6, the steering device 7, the tension bridle 8, the exit side looper 9, the tension bridle 10,
After passing through the skin pass mill 11, tension bridle 12, and shear 13, it is wound up by a coiler 14.

Further, the main steps and functions of the device of the present invention will be specifically described.

(1) Reduction zone 18 In the final pass of the final cooling zone 1 of the existing annealing furnace, the strip steel 2 was passed through the furnace atmosphere gas seal roll 3 to the water cooling tank 4 and the conventional pass was passed through the final pass of the final cooling zone 1. through the deflector roll 15, 16 and sealing device 17 ₁ led 'a furnace atmosphere gas seal rolls 3' strip 2 to the top of the path, iron strip surface by Jietsuto of heating a mixed gas of high hydrogen and nitrogen concentration of hydrogen Reduction zone 18 for reducing and removing oxides
Lead to.

In this reduction zone 18, the hydrogen concentration is 10 to 75% and the dew point is -6.
The time required to heat the mixed gas of hydrogen and nitrogen having an oxygen concentration of 0 ppm or less and 10 ppm or less to 500 ° C. to 750 ° C. to the strip steel and reduce and remove the iron oxide on the surface of the strip steel is calculated by the following formula. To decide.

t: time required for reduction (sec) δ: strip thickness (mm) γ _s : specific gravity of strip (kg / m ³ ) C _s : specific heat of strip (kcal / kg ° C) D: heated Injection pitch of mixed gas (m) t _g : Temperature of heated mixed gas (° C) t _sl : Temperature of strip steel at reduction zone inlet (° C) t _so : Temperature of strip steel at reduction zone outlet (° C) v: Injection velocity of heated mixed gas (m / sec) ν: Coefficient of kinematic viscosity of heated mixed gas (m ² / s) λ: Thermal conductivity of heated mixed gas (Kcal / mh ° C) , Reduction time t is the physical property values ν, λ and temperature t _g of the heated mixed gas (referred to as hot hydrogen gas), the strip steel plate thickness δ, the physical property values γ _s , C _s and the reduction zone inlet and outlet. Temperature t _sl , t
_so , as well as the jet speed v of the hot hydrogen gas and the pitch D of the jet nozzle.

The reduction zone inlet temperature t _sl is about 350 to 400 ° C, and the reduction zone outlet temperature t _so is 500 to 550 ° C required for reduction of the strip steel.
The above is preferable.

Further, the reduction time t varies depending on the hydrogen concentration of the hot hydrogen gas when the flow velocity v of the jetted hot hydrogen and the nozzle pitch D are fixed on the equipment. In terms of equipment cost, it is advantageous that the hydrogen concentration is high.

The minimum reduction time t is the temperature of the hot hydrogen gas 600
It takes about 6.7 seconds when the temperature is 75 ° C. and the hydrogen concentration is 75%, so the temperature of the steel strip may be raised to 500 ° C. and held for about 7 seconds.

(2) Gas sealing function Since the hydrogen gas concentration in the reduction zone 18 exceeds 3% of the explosion limit, the sealing device 17 is installed at the inlet and outlet of the reduction zone 18.
₁ , 17 ₂ are provided to block the reduction zone 18 from other parts,
Moreover, the furnace pressure of the existing final cooling zone 1, the outlet side cooling device 19 and the inert gas substitution chamber 20 is set to the reactor pressure of the final cooling zone P _{1 of the} reduction zone 18 P _{2 of the} outlet side cooling device 19. Assuming that the furnace pressure of the P ₃ inert gas substitution chamber 20 is P ₄ , the pressure of each furnace is controlled so as to maintain the relationship of 0 <P ₁ ≧ P ₂ ≦ P ₃ ≧ P ₄ > 0.

That is, in the present invention, the hot hydrogen gas having a high hydrogen concentration in the reduction zone 18 is designed not to flow into the existing final cooling zone 1 and the new outlet side cooling device 19.

Since the inert gas substitution chamber 20 is preferably weakly reducing in order to maintain the surface properties of the strip steel reduced and activated in the reduction zone 18 to be suitable for plating, it is preferable that the hydrogen concentration is maximum. The inflow of hot hydrogen gas from the reduction zone 18 is allowed until it reaches 2%. However, if the atmosphere of the inert gas replacement chamber 20 exceeds 2% hydrogen concentration, the inert gas replacement chamber 20
An inert gas is introduced to dilute the hydrogen concentration. In this case, since the furnace pressure P ₄ of the inert gas substitution chamber 20 increases,
An automatic valve (not shown) that releases atmospheric gas to the atmosphere is provided.

Further, when the hydrogen concentration in the inert gas substitution chamber 20 increases beyond 2%, the inert gas having a hydrogen concentration exceeding 2% flows into the vacuum seal device 22 side on the outlet side of the inert gas substitution chamber 20. If the vacuum breaks and air enters, there is a danger of explosion, so the hydrogen concentration in the inert gas substitution chamber 20 is controlled to 2% or less.

The reduction zone 18 is as short as about 80 to 149 m in length of the strip steel. Further, the reduction zone 18 is provided with sealing devices 17 ₁ and 17 ₂ at the inlet and the outlet so as to be separated and independent from other portions, and further, gas sealing is performed at a pressure higher than atmospheric pressure to prevent air from entering. Moreover, the furnace body itself has a gas-tight structure. Therefore, since the hot hydrogen gas in the reduction zone 18 does not flow to the final cooling zone 1 and the outlet side cooling device 19, it is possible to operate the hydrogen concentration within the explosion limit of 3% or less in any portion.

(3) Outlet side cooling device 19 This cooling device is for adjusting the strip steel temperature to a temperature suitable for vapor deposition plating. That is, the strip steel temperature has a range that can be vacuum-deposited depending on the kind of the plated metal (for example, zinc is 190 to 420 ° C, aluminum is about 200 to 660 ° C, and ceramics is about 400 to 1000 ° C).
C.), if it exceeds this range, the plated metal causes poor adhesion and peels off. This cooling device is provided to prevent this.

(4) Adjustment of hot hydrogen gas The hot hydrogen gas is heated through a heat exchanger (not shown), and the hydrogen concentration may be adjusted by using ammonia cracked gas or by using a hydrogen cylinder. It may be supplied, but it is performed using a nitrogen gas and a mixer (not shown).

Hereinafter, experimental examples for demonstrating the effect of the present invention will be described.

Experimental Example 1 A 0.8 mm thick × 100 mm square degreased steel plate (spcc) was heated to about 800 ° C. for 90 seconds in a mixed gas of 3% hydrogen, 97% nitrogen and a dew point of −20 ° C. as an atmosphere, and then gradually heated. After cooling and quenching, 4
After holding at 00 ° C for about 2 to 3 minutes, annealing treatment of cooling to 250 ° C was performed, and then hydrogen 75%, nitrogen 25%, oxygen 10pp
A mixed gas having m and a dew point of -60 ° C was heated to 600 ° C for jetting, heated to about 500 ° C, and reduced for about 12 seconds including the heating time.

Next, hydrogen 1%, nitrogen 99%, oxygen 2ppm, dew point -4
Adjust the temperature of the mixed gas at 0 ℃ to 30 ℃ and spray it at 250
After cooling to 0 ° C., zinc was vacuum-deposited at a vacuum pressure of 0.05 Torr to obtain a sample having an adhesion amount of zinc of 30 g / m ² .

About this sample 180 degree contact bending (sample 2
After folding it into close contact), a Scottish tape was attached to the bent portion and an adhesion test was conducted. The results of the adhesion test were good, and no peeling of the plating was observed.

Experimental Example 2 The same annealed steel sheet as in Experimental Example 1 was changed to 15% hydrogen, 85% nitrogen, and dew point −60 ° C. in the composition of the mixed gas in Experimental Example 1, heated to 650 ° C., and jetted to the above steel sheet. The steel sheet was heated to about 550 ° C. and reduced for about 22.3 seconds including the heating time.

Then, using the same mixed gas as in Experimental Example 1, after cooling to 250 ° C., zinc was vacuum-deposited at a vacuum pressure of 0.05 Torr to obtain a sample having an adhesion amount of zinc of 60 g / m ² .

About this sample, Experimental Example 1 after 180 ° contact bending
The results of the peel test similar to the above showed good adhesion.

Experimental Example 3 When Experimental Examples 1 and 2 were applied to a continuous annealing furnace having a plate thickness of 0.8 mm and 400 m / min, the length of the reduction zone 18 in the attached drawings was as follows under the conditions of Experimental Examples 1 and 2. is there.

In the case of the conditions of Experimental Example 1; Hot hydrogen gas composition: Hydrogen: 75% Nitrogen: 25% Oxygen: 1 to 10 ppm Hot hydrogen gas dew point: -60 ° C Hot hydrogen gas temperature: 600 ° C Gas jetting to a steel plate, hot hydrogen gas jetting Steel plate temperature before: 400 ° C Steel plate temperature after hot hydrogen gas jet: It takes about 5 seconds to heat to 500 ° C, and when the steel strip temperature of 500 ° C is maintained for 7 seconds, the length of the reduction zone 18 is about 80 m. It is enough.

In the case of the conditions of Experimental Example 2; Hot hydrogen gas composition: Hydrogen: 15% Nitrogen: 85% Oxygen: 1-10 ppm Hot hydrogen gas dew point: -60 ° C Hot hydrogen gas temperature: 650 ° C Hot hydrogen gas is jetted onto a steel sheet. It takes about 12.3 seconds to heat the steel plate temperature from 400 ℃ to 550 ℃.
When the temperature is kept at 50 ° C for 10 seconds, the reduction zone 18 has a length of about 1
49m is enough.

〔The invention's effect〕

As described above in detail, according to the apparatus of the present invention, compared with the vacuum deposition zinc plating line in which the vacuum sealing device and the vapor deposition device are provided on the rear surface of the conventional annealing reduction furnace via the inert gas replacement chamber, The plate speed can be increased 2 to 4 times.

Therefore, in the device of the present invention, productivity is improved by 2 to 4 times as compared with the above-mentioned conventional zinc plating line, and there is an effect that the manufacturing cost of the plating steel plate can be greatly reduced.

Further, in the present invention, even if an explosion should occur, the damage to the equipment is small, so that the reduction zone can be made into a high-concentration hydrogen gas atmosphere above the explosion limit, thereby improving the activation effect of the steel strip surface. It is possible to obtain a steel strip with excellent adhesion.

In the device of the present invention, the cold-rolled steel plate and the plated steel plate can be manufactured separately on the same line.

[Brief description of drawings]

The drawings are schematic views showing an embodiment of the present invention. 1 ... Final cooling zone of continuous annealing furnace, 17 _{1 to} 17 ₅ ... Sealing device, 18 ... Reduction zone, 19 ... Outlet side cooling device, 2
0 ... Inert gas replacement chamber, 22 ... Vacuum seal device, 2
3 ... first vapor deposition chamber, 24 ... second vapor deposition chamber

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Nakamura 5 Ishizu Nishimachi, Sakai City, Osaka Prefecture Sakai Works, Nisshin Steel Co., Ltd. (72) Inventor Takehiko Ito 3-4-1 Marunouchi, Chiyoda-ku, Tokyo Date In Shin Steel Co., Ltd. (72) Inventor Takuya Aiko 5 Ishizu Nishimachi, Sakai City, Osaka Prefecture Nisshin Steel Co., Ltd. Sakai Works

Claims (1)

[Claims] 1. A continuous annealing furnace for strip steel is provided with a reducing zone for reducing and removing an oxide film on the surface of the strip, and an inert gas is provided on the rear surface of the reducing zone through a cooling device for cooling the strip by a gas jet. A continuous vacuum vapor deposition apparatus for strip steel, comprising a substitution chamber and a plurality of vacuum sealing devices and at least one vacuum vapor deposition device provided on the rear surface of the inert gas substitution chamber.