JPH01225758A - Apparatus for producing minimized spangle steel sheet - Google Patents

Abstract

PURPOSE:To stably produce a minimized spangle steel sheet having beautiful appearance by providing a heater which can move upward and downward in the traveling direction of the steel sheet between wiping nozzle and spangle adjusting devices at the time of galvanizing the steel sheet. CONSTITUTION:A strip 10 emitted from a galvanizing bath surface is first adjusted in the coating weight by the wiping device 12 and is then uniformed in the coating weight in the transverse direction by pass-stabilizing rolls 14 constituted of a roll pair. The strip is then fed to a heating furnace 16 where the strip is heated by plural burners 20 arranged longitudinally and transversely; thereafter, the strip is subjected to spangle adjustment by the spangle adjusting device 18. This heating furnace 16 is so provided that the furnace can move upward and downward along the traveling direction of the strip 10 to allow production of a wide range of strip sizes. The spangles are thereby minimized and the minimized spangle steel sheet having the beautiful surface is stably obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an apparatus for manufacturing minimized spangle steel sheets in a continuous hot-dip galvanizing line, particularly a miniaturized steel plate that performs spangle adjustment after mild alloying using a heating furnace. The present invention relates to a manufacturing device for dospangled steel sheets.

(Prior art) When manufacturing continuous hot-dip galvanized steel sheets, a flowery surface pattern called spangles is produced, but regular spangle steel sheets have such spangles beautifully formed over the entire surface of the sheet. Galvanized steel sheets are used in this form.

On the other hand, when the galvanized surface of a hot-dip galvanized steel sheet is used as a base for painting, etc., the irregularities and crystal orientation differences seen in the spangles tend to affect the surface smoothness and cause unevenness when chemical conversion treatment is applied. There is a need to. The steel plate obtained in this way is called a minimized spangled steel plate.

Conventional methods for manufacturing minimized spangled steel sheets include: ■ After plating, spraying water or an aqueous solution containing special chemicals onto the plating surface to eliminate the spangles;
■ After plating, spray zinc powder onto the plating surface to eliminate spangles, and ■ Use a low PB zinc bath.
There is a method of eliminating spangles by applying high pressure in a skin pass after plating.

(Problem to be solved by the invention) However, even with the conventional method for which so many methods have been proposed, low pb operation cannot be performed on a line that also manufactures regular spangled steel sheets, and minimization When manufacturing dospangles, it is necessary to eliminate the spangles by spraying water or an aqueous solution containing special chemicals, or by spraying zinc powder.Separate production lines for each product reduce equipment costs. This is because it is unthinkable in today's world, where such things are in demand. but,
These methods pose the following problems.

(1) Spangles occur due to cooling of the strip edge after plating.

(2) Occurrence of spangled unevenness due to differences in plating amount in the width direction of the strip.

(3) Occurrence of spangle irregularities and out of focus due to Tomoe air pressure fluctuations, etc.

(4) Occurrence of ripples due to oxidation of the plating surface during wiping.

Since these defects become apparent even after painting, they are a major obstacle to upgrading hot-dip galvanized steel sheets.

Spangle unevenness occurs even when there are subtle variations in the amount of plating or small fluctuations in air pressure, so it is very difficult to manage. In addition, regarding the suppression of ripple patterns,
The 0□ concentration is delicately controlled in a sealed N2 atmosphere,
The only way is to perform N2 wiping. In other words, 1. In order to suppress the occurrence of such ripple patterns, N2 wiping and atmospheric plating are required, and their management is not easy.

Therefore, an object of the present invention is to provide a simple device that can stably produce a minimized spangled steel sheet without spangle unevenness, pits, or ripple patterns, and that is easy to manage.

(Means for Solving the Problems) Therefore, as a result of various studies to solve the problems, the inventors of the present invention have found that: 1. Regarding the occurrence of spangles, the present inventors have found that: By heating, it is possible to suppress the occurrence of spangles and eliminate the ripple pattern at the same time. Also, regarding the heating pattern in the width direction of the strip, by raising and lowering the heating furnace, the dry line of the zinc when entering the spangle adjustment device can be flattened. The present invention was completed based on the knowledge that uniformity of the galvanizing amount in the width direction of the strip could be achieved by using a path stabilizing roll directly above the wiping nozzle. did.

Here, the gist of the present invention is to provide a minimized spangle that includes a wiping nozzle that adjusts the coating weight of a steel sheet pulled up from a molten zinc bath, and a spangle adjustment device provided above the wiping nozzle. The apparatus for producing a minimized spangled steel plate is characterized in that a heating device that can be moved up and down along the running direction of the steel plate is provided between the wiping nozzle and the spangle adjustment device.

Furthermore, in a preferred embodiment of the present invention, a path stabilizing roll of a steel plate may be further provided between the wiping nozzle and the heating device, and by adopting such a configuration,
The amount of zinc plating in the width direction of the strip can be made uniform, and the occurrence of uneven spangles can be effectively prevented.

Thus, according to the present invention, the temperature of the galvanized layer on the strip is raised again by heating, and the locally generated fine spangles and pits are remelted and eliminated. Furthermore, since the diffusion rate of substances within the galvanized layer also increases, zinc oxide on the galvanized surface is also dissipated. Furthermore, when a pass stabilizing roll is used during the production of normal minimized spangled steel sheets, roll marks are printed on the plating surface, but according to the present invention, these print marks are also erased by heat treatment. Path stabilizing rolls can also be provided prior to the furnace.

In implementing the present invention, the heating method is an open flame so that it can follow changes in strip size and plating amount, and the burner mount surface is made of stainless steel.
It is better to suppress the amount of heat retained in the heating furnace.

Furthermore, in another preferred embodiment of the present invention, the direct-fired burner has a structure in which a plurality of direct-fired burners are arranged in the strip traveling direction and width direction, and it is possible to perform focused heating of the strip edge portion where the cooling rate is high. Make it so. This makes it possible to flatten the dry lines of zinc, making it possible to manufacture minimized spangled steel sheets that are uniform in the width direction. Also,
Since this heating furnace can be moved up and down like the spangle adjustment device, it is possible to manufacture strips of a wide range of sizes.

(Operation) Next, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1' is a diagram illustrating the outline of a manufacturing apparatus for a minimized spangled steel sheet according to the present invention, in which the strip 10 that has left the surface of the sand-dip galvanizing bath is first cleaned by a wiping device 12, which is a conventional means. The amount is adjusted, and then passes through a path stabilizing roll 14 consisting of a pair of rolls,
It is sent to a heating furnace 16, where it is heated by burner ignition, and then sent to a spangle adjustment device 18, where spangle adjustment is performed.

This spangle adjustment device 18 is a conventional device and is not particularly limited. For example, water spraying may be done by method.

Further, the path stabilizing roll 14 is not necessarily required, but as already mentioned, it is preferable to provide it in order to perform uniform plating. Although the shape and dimensions are not limited to specific ones, steel (C
It may be equivalent to the touch roll manufactured by R.Metsuki).

According to the present invention, the strip path near the wiping device 12 is stabilized by employing the path stabilizing roll 14. Further, the roll pattern created on the strip 10 by the path stabilizing roll 14 is erased in the heating furnace at the next stage. At the same time, the ripple pattern during wiping is also eliminated in this heating furnace. In the case of double-sided plating, both sides of the strip are heated.

Next, since this heating furnace is configured so that the heating area is variable, the ignition zone of the burner is determined according to the thickness, width, and amount of plating of the strip, and the drying line of the zinc in the width direction of the strip is determined. control.

It is preferable to control the heating area as follows.

For example, when producing a thin plate with little sensible heat, burners in the second and third stages shown in FIG. 2, which will be described later, are used in the entire width direction of the strip, and burners at the edge of the strip are also used. It is preferable to use two edge burners for thin and wide materials.

In addition, when manufacturing a thick plate, a second or third stage burner is used across the entire width of the strip. One edge burner is sufficient regardless of basis weight and strip width.

On the other hand, this heating furnace can be moved up and down in the strip running direction, and the mechanism for this may be a conventional one, but since its purpose is to adjust the dry line, it is necessary to adjust the thickness, area weight, line speed, pot Using an empirical formula that takes into account the temperature of the intruding material, etc., determine the distance between the spangle adjustment device and the heating furnace and the height of each from the bath surface to flatten the dry line.

In this way, adjust the pangle adjustment device 1 according to the dry line.
Adjust the height l of 8 to create a completely minimized spangle. Since the strip is heated to a certain degree in the heating furnace, it undergoes slight alloying before entering the spangle adjustment device, so there is no need for the delicate adjustment of l that is done in the conventional method. This enables stable production of minimized spangled steel sheets. Moreover,
By moving the heating furnace itself, even if it is a movable type, it is possible to continue operation with the spangle adjusting device 18 substantially fixed, which is of great practical benefit.

FIG. 2 is a schematic explanatory diagram showing an example of the arrangement of burner rows in a heating furnace used in the present invention, and FIG. 3 is a plan view thereof.

The burner rows, which are installed facing each other in the width direction to cover the strip running upwards, are divided into multiple sections as shown in the illustration, so that the heating area, heating intensity, etc. can be adjusted as appropriate. In the example shown, independently adjustable burners are installed in each of the 1st to 4th stages in each row a to e. The specific installation and mechanism will be clear to those skilled in the art from the above description.

In the illustrated example, if each stage 1 to 4 is turned on, when the a and e rows are ignited, the a and e
each burner ignites.

On the other hand, when stages 2 and 3 are each on, when stages a and e are ignited, the two central burners of a and e (indicated by diagonal lines in the figure) are ignited. There is. Therefore, burner control can be performed easily and accurately.

Although not shown, it is sufficient to install a hoist-type lifting device for the heating furnace, which is already used in the lifting device of the spangle adjustment device, and as already mentioned, its position control is not very important. Since accuracy is not required, this can be done relatively easily.

Next, as shown in Figure 3, the proximity distance ([1)] between the strip and the burner is not particularly limited, but the purpose is to prevent local heating and improve the controllability of the zinc dry line in the width direction. It is preferably 200 to 4001.

The heating method of such a burner is generally a gas or liquid fuel injection burner, but electrical induction heating is also possible in principle. In view of equipment costs, running costs, etc., a fuel injection burner is preferred in the present invention.

Further, there is no particular restriction on the specific control means for such a heating furnace, especially burner combustion, and from the above description, those skilled in the art will be able to realize the effects of the present invention by using appropriate control means. .

Next, examples of the present invention will be described.

EXAMPLE Using the apparatus schematically shown in FIG.
4.5+u+, plate material of ordinary steel or 100 grade HT material with a plate width of 610 to 1250 mm, soaked at a soaking temperature of 500 to 85 mm.
0℃, plate temperature 430-480℃, bath temperature 450-470℃
Minimized spangle steel sheets were manufactured under plating conditions of .degree. C. and line speed of 25 to 180++p.

The burners installed in the heating furnace are arranged as shown in Figures 2 and 3, with one burner installed at each edge of the central zone.
I used this book.

For comparison, a minimized spangled steel sheet was also produced using the conventional apparatus shown in FIG. 1 without the heating furnace 16 and path stabilizing roll 14. Evaluation,
A sample without reduction by skin pass was used.

The results are summarized in Table 1, and according to the present invention, the obtained steel sheets are all minimized spangled steel sheets, and the surface luster disappears and the adhesion decreases due to excessive alloying. There were no other problems. In particular, according to the present invention, the effect of eliminating edge spangles and ripple patterns was remarkable.

Note to Table 1: Invention Example 1 does not use rolls for path stabilization (effects of the invention) As detailed above, according to the conventional method, hot-dip galvanized steel sheets have spangle unevenness, bits and ripple patterns on the surface. However, according to the present invention, by heating the plated strip before adjusting the spangle, it is possible to produce a stable minimized spangle steel sheet. , which has great practical significance.Additionally, by heating, it is possible to eliminate the ripple pattern that occurs during wiping, and it also makes it possible to use a path stabilizing roll directly above the wiping device. When using this method, the path of the plate near the wiping device is stabilized, and the amount of plating in the width direction of the strip is also stabilized. At the same time, by heating the edges of the strip in a heating furnace, the dry zinc line of the strip entering the spangle adjustment device can be flattened. As a result of these effects, according to the present invention, it is possible to stably manufacture a minimized spangled steel plate with a beautiful surface appearance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an outline of the method of the present invention; FIG. 2 is a schematic explanatory diagram showing the arrangement of heating burners in the heating furnace shown in FIG. 1; and FIG. 3 is a diagram showing how the burners are installed. FIG. 2 is a schematic plan view of FIG. 10: Strip 12: Wiping device 14: Bath stabilization roll 16: Heating furnace 18: Spangle adjustment device

Claims (1)

[Claims] An apparatus for manufacturing a minimized spangled steel sheet, comprising a wiping nozzle for adjusting the coating weight of a steel sheet pulled out of a molten zinc bath, and a spangle adjustment device provided above the wiping nozzle, the wiping nozzle and 1. An apparatus for manufacturing a minimized spangled steel sheet, characterized in that a heating device that can be moved up and down along the running direction of the steel sheet is provided between the spangle adjustment device and the heating device.