JPS5896872A - Vacuum deposition device - Google Patents

Abstract

PURPOSE:To make the responsiveness of the rate of evaporation fast and to prevent splashing by installing a heater which is a heating soruce in the upper part in a vacuum deposition furnace and floating a carbon block in the bath. CONSTITUTION:When a shutter 4 is opened in the stage of vapor deposition, zinc vapor is plated through an opening 6 on a steel strip 10 which travels in, for example, a right direction above the body 1 of the vapor deposition furnace. Here, molten zinc 7 is heated directly by the heater 8 in the upper part of the inside of the furnace or is heated with a carbon block 11 floating in the zinc 7 and evaporates successively from the surface layer. Thus, the evaporation responds quickly to the change in the rate of heating from the heater 8 and since the time for settling decreases, the generation of off-specification products decreases. The formation of the oxide film on the liquid surface of the zinc is suppressed by the reducing force of the block 11, splashing is made difficult to arise and the sticking of liquid drops upon the products is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous vacuum deposition apparatus for, for example, galvanizing steel strips, and to a deposition furnace with fast response of deposition rate and good plating performance.

As a method of continuously forming a galvanized film on a copper strip,
In addition to the conventional molten zinc bath method and electroplating method, the vacuum evaporation plating method is attracting attention because of its advantage over plating on only one side. As shown in FIG. 1, a conventional vapor deposition furnace is one in which heating is performed from the bottom of the furnace.

In FIG. 1, 1 is a furnace housed in a vacuum atmosphere, and molten zinc 7 is held inside this furnace body. There is an opening 6 in a part of the ceiling 3, and it is covered with a 7-layer 4 which is rotatably driven around a hinge 5. A heater 8 as a heating source is installed below the furnace, and both the furnace body 1 and the heater 8 are covered with a heat insulating material 9.

During deposition, the shutter 4 is open, and the molten zinc 7 is heated through the bottom plate of the furnace body 1 by the heater 8, vaporized and plated onto the copper strip 10 running through the opening 6 above the deposition furnace. Molten zinc is continuously supplied from the supply duct 2 in an amount equal to the amount of evaporation.

Such conventional vapor deposition units have the following drawbacks.

(1) On a plating process line, for example, when the thickness of the supplied copper strip changes, it may be necessary to instantaneously change the weight per unit area of the steel strip to be plated. In this vapor deposition furnace, the heat capacity of the molten zinc in the vapor deposition furnace and the furnace body itself is large, so even if the heating amount of the heating source is changed instantaneously, the response of the zinc evaporation rate is slow, and the rate of zinc evaporation may exceed the standard by the time it stabilizes. The disadvantage is that a large number of products with specific weights are produced and then shuffled. Example O is line speed 3
Q m/1111, basis weight 70f/rr? It is expected that the vapor deposition furnace planned for this line will take about 6 minutes to settle, and during this time a 180m long product will be out of specification.

(2) Since the zinc bath is heated from the bottom, bubbles are generated by boiling at the bottom of the zinc bath, which rise upward in the liquid and exit from the liquid surface. At this time, a so-called splash occurs in which the liquid scatters. In addition, an oxide film is likely to form on the liquid surface,
When a film is formed, air bubbles accumulate below the bubbles, and when they grow to a certain size, they instantly destroy the film, resulting in a large splash. If splash occurs, droplets may adhere to the copper strip, resulting in product defects.

The present invention has been made to solve the above-mentioned drawbacks and realize a heating method with a fast response speed. This is a vapor deposition furnace characterized by having carbon blocks suspended therein, and it is possible to realize a vapor deposition furnace that has quick response and prevents splashing.

Hereinafter, the embodiments of the present invention shown in FIGS. 2 to 6 will be described in detail.

Example 1゜ FIG. 2 shows an embodiment of the vapor deposition furnace of the present invention.

In FIG. 2, a heater 8 serving as a heating source is installed above molten zinc 7 in a furnace, and carbon blocks 11 are suspended in the zinc bath. The rest of the structure is the same as the conventional structure shown in FIG. 1, so a description thereof will be omitted.

In FIG. 2, when the shutter 4 is open and the copper strip 10 is running above the vapor deposition furnace, for example to the right in the figure, the molten zinc 7 is directly heated by the heater 8 above, or the carbon block 11 is heated and evaporated through the opening 6 to plate the steel strip 10.

With such a configuration, the following effects are achieved.

■ If simply heated from above, the heat absorption rate of the surface of molten zinc is very small, approximately 0.1, so direct radiation heating from above is difficult to achieve because the heater temperature becomes too high. When the block is suspended in a liquid, the heat absorption coefficient of the surface of carbon is as large as about 1.0, so the overall heat absorption coefficient can be improved, and a method of heating from above can be realized.

(2) According to the present invention, since zinc is heated from above, it evaporates from the surface layer, so it quickly responds to changes in the amount of heat from the heating source. In other words, the time required for stabilization becomes extremely short, and the occurrence of non-standard products is reduced.

■ At the same time, the carbon block's reducing power suppresses the formation of an oxide film on the surface of the zinc liquid, making splash less likely to occur and preventing droplets from adhering to the product.

■ In the conventional method, the zinc bath surface is 550℃ and the furnace bottom plate is 600℃.
If a steel plate was used for the bottom of the furnace, the corrosion rate would be extremely high, and for industrial use it would have been necessary to use ceramic instead of steel.However, according to the present invention, the zinc bath surface can also be Since the temperature of the furnace bottom is almost the same at 550°C, steel plates can be used, which reduces the manufacturing cost of the furnace body.

Example ■.

FIG. 3 shows Example (2). In FIG. 3, a heater 8 as a heating source is installed above molten zinc 7 in a furnace, and a block 11 made of a material with a specific gravity smaller than zinc and whose surface is coated with carbon 12 is floating in the zinc bath. There is.

The rest of the structure is the same as the conventional structure shown in FIG.

This has the same functions and effects (1) to (2) as in Example I.

Example ■.

FIG. 4 shows Example (2). In FIG. 4, a heater 8 serving as a heating source is installed above molten zinc 7 in a furnace, and carbon pellets 11 are suspended in the zinc bath. Others are 1st
It is the same as the conventional structure shown in the figure.

As a result, it has the same action and effect as in Example (■), and furthermore, () There is a certain relationship between the evaporation rate per unit area and the bath temperature, and when the total amount of evaporation is constant, the pellet floats. As a result, the evaporation area decreases and the bath temperature rises.Using this relationship, the desired bath temperature can be easily obtained by manipulating the number of pellets floating in the bath.

be effective.

Example ■.

FIG. 5 shows Example (2). In FIG. 5(A), a heater 8 serving as a heating source is installed above the molten zinc bath in the furnace, and a carbon parallel grid 11 (FIG. 5(B) is a plan view of the parallel grid) is suspended in the zinc bath. ing.

The rest of the structure is the same as the conventional structure shown in FIG.

As a result, in addition to the same functions and effects as in Example I, there are also the following: (1) Since the surface area of the carbon parallel girder is large, heat transfer between the carbon and the molten zinc is improved.

be effective.

Example V.

1. Structure FIG. 6 shows Example (2). In FIG. 6, a heater 8 serving as a heating source is installed above molten zinc 7 in a furnace, and a block 11 having a specific gravity smaller than that of zinc and having a nickel shape or many holes is floating in the zinc bath. There is. The rest of the structure is the same as the conventional structure shown in FIG.

7 and 8 show examples of the shape of the block 11, (A
) is a side view, and (B) is a plan view.

The effects achieved by the configuration of the vacuum deposition section of the present invention described above are summarized as follows.

■ If simply heated from above, the absorption rate of the surface of molten zinc is very small at approximately 0.1, so direct radiation heating from above is difficult to implement because the heater temperature becomes too high.・When a Nicum-like or carbon block with many holes is suspended in a liquid, the apparent blackness of the block surface (which is the same as the heat absorption rate) increases due to the cavity effect, causing the shape to change. If selected appropriately, the absorption rate can be made close to 1.0, and as a result, the overall heat absorption rate can be improved, so a method of heating from above can be adopted.

(2) According to the present invention, since zinc is heated from above, it evaporates from the surface layer, so it quickly responds to changes in the amount of heat from the heating source. For example, line speed 30 m/mi
n, Settling time is 60 seconds or more with a unit weight of 70V/door line
It takes about 1 minute. In other words, the time spent in the trench for settling is very short, which reduces the chance of producing non-standard products.■ There is a certain relationship between the evaporation rate per unit area and the bath temperature, so when the overall evaporation amount is constant, the block When floating, the evaporation area decreases and the bath temperature increases, but the present invention can improve the apparent absorption rate while maintaining a constant evaporation area and preventing the bath temperature from increasing more than necessary.

■ In the conventional method, the zinc bath surface is 550℃ and the furnace bottom plate is 600℃.
If a steel plate was used for the bottom of the furnace, the corrosion rate would be very high, and for industrial use it would have been necessary to use ceramic instead of a steel plate. However, with the method of the present invention, the zinc bath surface also Since the bottom temperature is almost the same at 550°C, steel plates can be used and the cost is low.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional vacuum evaporation section, FIGS. 2 to 6 are diagrams showing embodiments of the vacuum evaporation section of the present invention, FIG.
FIG. 8 is a diagram showing shapes of carbon blocks other than those shown in FIGS. 2 to 6. Sub-agent 1) Clearance agent Ryo Hagiwara - Figure 1 Figure 2 Figure 0-4 Spear 3 Figure So' Fang 4 Figure / 8-5 Figure - 710 / 1-6 Figure Off Figure O 8 Figure

Claims (1)

[Claims] A vacuum evaporation section characterized in that a heating source heater is installed above the furnace, and carbon blocks are suspended in the bath.