JP2799225B2 - Descaling method of titanium plate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of descaling a titanium plate, and more particularly, to a continuous annealing pickling of a plate made of pure titanium or a titanium alloy (hereinafter referred to as a titanium plate). The present invention relates to a method of descaling a titanium plate after annealing in a line using a salt bath.

(Prior Art) In a continuous annealing and pickling line for a titanium plate, the descaling of the titanium plate is performed as shown in FIG.
The immersion inlet roll (3) that moves up and down on the titanium plate entry side of the salt bath (6) while the immersion exit roll (4) moves up and down on the titanium plate exit side of the salt bath (6). ), The titanium plate is pressed from above and sequentially immersed in the salt bath (6).
In addition, both the rolls (3) and (4) are partially or almost completely immersed in the salt bath (6). In FIG. 2, (2) is a roll for introducing the titanium plate (1), and (5) is a roll for leading out the titanium plate (1) after immersion.

The immersion roll needs to have good corrosion resistance and abrasion resistance, and in view of this, cast iron rolls have been used.

(Problems to be Solved by the Invention) However, the conventional method for descaling a titanium plate is as follows.
When the titanium plate and the immersion delivery roll come into contact with each other in the salt bath, there is a problem that a spark phenomenon occurs and a concave spark is generated on the titanium plate. Occasionally, a spark hole in the form of a through hole may occur. The occurrence of such a spark flaw is a serious problem leading to poor quality.

The spark is caused by a large electrochemical potential difference (about 1 V) between the titanium plate and the immersion discharge roll (cast iron) in the salt bath. That is, when the two come into contact in the salt bath, an electrochemical cell having an electromotive force of about 1 V, that is, a battery is formed at that moment, and a large amount of current flows instantaneously and sparks.

Therefore, in order to prevent the occurrence of a spark phenomenon, a method has been attempted in which a titanium roll is used as the immersion exit roll or an external current is applied to the immersion exit roll (cast iron) to reduce the potential difference. However, there is a problem in that both of them cause a significant reduction in roll life and economy.
Further, the latter method of applying an external current requires a facility for collecting gas generated by electrolysis.

In addition, in the entry roll for immersion, a spark phenomenon occurs when it comes into contact with the titanium plate, but since the surface of the titanium plate is covered with scale, its occurrence frequency is small and spark scratches are slight. There is not much problem, and firstly, there is a demand for establishing measures to prevent the occurrence of spark damage due to the immersion delivery roll.

The present invention has been made in view of such circumstances, and its purpose is to reduce the dipping discharge roll and the titanium plate without causing a reduction in roll life and a significant reduction in economy as described above. An object of the present invention is to provide a method for descaling a titanium plate that can prevent the occurrence of spark phenomena and spark flaws due to contact.

(Means for Solving the Problems) In order to achieve the above object, a method for descaling a titanium plate according to the present invention has the following configuration.

That is, the method for descaling a titanium plate according to claim 1 includes a dipping inlet roll that moves up and down on the titanium plate entry side of the salt bath while the titanium plate is running, and a vertical roll on the titanium plate exit side of the salt bath. With the moving outflow roll for immersion, the titanium plate is pressed from above, and in a method of descaling a titanium plate to be sequentially immersed and descaled in a salt bath,
The liquid level of the salt bath is detected, and at least the lowermost part of the immersion inlet roll is adjusted to a position lower than the liquid level of the salt bath according to the liquid level. This is a method of descaling a titanium plate, wherein the lowermost part of the side roll is adjusted to a position higher than the liquid level of the salt bath.

The descaling method according to claim 2, wherein the position of the entry roll and the exit roll for immersion is adjusted, and a titanium plate that travels between the entry roll and the exit roll for immersion, and a liquid surface of the salt bath. 2. The method for descaling a titanium plate according to claim 1, wherein the angle between the target and the target is controlled to 0.2 to 3.0 degrees.

The descaling method according to claim 3, wherein the distance in the titanium plate traveling direction of the non-immersed portion of the titanium plate between the immersion entrance roll and the exit roll is adjusted to 500 to 2000 mm, and the immersion exit side. The descaling method for a titanium plate according to claim 1, wherein the distance between the lowermost part of the roll and the liquid surface of the salt bath is adjusted to 25 to 100 mm.

(Operation) As described above, the descaling method of the titanium plate according to the present invention comprises, as described above, a dipping entrance roll that moves up and down on the titanium plate entry side of the salt bath and a dipping movement that moves up and down on the titanium plate exit side of the salt bath. Pressing the titanium plate from above with the delivery roll,
Since they are sequentially immersed in a salt bath, the titanium plate can be descaled one after another.

Also, the liquid level of the salt bath is detected, and at least the lowermost part of the immersion entry roll is adjusted to a position lower than the liquid level of the salt bath according to the liquid level. The lowermost part of the delivery roll is adjusted to a position higher than the liquid level of the salt bath. Therefore, although the immersion delivery roll and the titanium plate are in contact with each other, the contact position is higher than the liquid level of the salt bath, so that the amount of the salt bath is reduced at the contact portion, and the immersion delivery roll is contacted. Since the electric resistance between the titanium plate and the titanium plate becomes large, it is difficult to form a battery having a large electromotive force between the discharge roll for immersion and the titanium plate. It is less likely to occur.

The method according to the present invention is characterized in that the positions of the entry roll and the entry roll for immersion are adjusted as described above, and the adjustment can be easily and inexpensively. As compared with the case where a roll made of titanium is used, the economic efficiency is excellent, and the economic efficiency is not significantly reduced. Further, since the immersion delivery roll is not immersed in the salt bath, the life is rather improved.

Therefore, according to the method according to the present invention, the occurrence of a spark phenomenon and the occurrence of spark flaws based on the contact between the immersion delivery roll and the titanium plate are reduced without causing a reduction in roll life and a significant reduction in economic efficiency. Can be prevented.

By adjusting the position of the immersion entrance roll and the exit roll, the angle between the titanium plate running between the immersion entrance roll and the exit roll and the liquid surface of the salt bath is set to 0.
If the angle is set to 2 degrees or more, the amount of salt liquid at the contact portion between the immersion discharge roll and the titanium plate decreases with an increase in the angle, and the spark phenomenon does not occur reliably. However, when the temperature exceeds 3.0 degrees, the amount of the salt solution in the vicinity of the contact portion becomes too small, becomes non-uniform, and unevenness is generated in the descaled skin of the titanium plate. In order to do this, it is better to make it 3.0 degrees or less.

Further, the distance (x) in the running direction of the titanium plate of the non-immersed portion of the titanium plate between the entrance roll and the exit roll for immersion is 500 to 2
000 mm and the distance (y) between the lowermost part of the immersion delivery roll and the liquid level of the salt bath was 40 to 100 mm.
Adjusting to ensures that the spark phenomenon can be reliably prevented and that a good descaled skin can be obtained.
The above distance (x): less than 500 mm or / and distance (y): 25 mm
If the distance (x) is less than 2000 mm and / or the distance (y) is more than 100 mm, the spark phenomenon cannot be completely prevented.
The non-scaled skin of the titanium plate may be uneven.

(Example) Example 1 FIG. 1 shows a schematic view of the descaling state of the titanium plate according to Example 1. The entry-side roll (3) for immersion and the exit-side roll (4) for immersion are formed by molding a cast iron plate having a thickness of 10 mm into a roll shape. As shown in FIG. 1, the titanium plate (1) is pushed from above by the immersion entry roll (3) and the immersion exit roll (4) while running the descaling material titanium plate (1). And descaling in a salt bath (6).

At this time, the liquid level of the salt bath is detected by an ultrasonic liquid level meter, and the rolls (3) and (4) are moved up and down according to the liquid level, and the entrance roll (3 )
The position of the inlet roll (3) is adjusted so that the lower part (ie, equivalent to 40% of the whole) is immersed in the salt bath, and the titanium between the inlet roll (3) and the outlet roll (4) is adjusted. The distance (x) of the non-immersion part of the plate is adjusted to 40 mm, and the distance (y) between the lowermost part of the delivery roll (4) and the liquid level of the salt bath.
Was adjusted to 80 mm. The titanium plate (1) after descaling was washed with water and dried.

As a result, descaling could be performed without generating a spark phenomenon and spark flaw, and non-scaling was not observed on the descaled skin, and the surface quality after descaling was good.

Example 2 A titanium plate was removed by the same method as in Example 1 except that the distance (y) between the lowermost part of the delivery roll (4) and the liquid level of the salt bath was changed as a parameter. The scale was performed, and the relationship between the distance (y) of the parameter and the frequency of occurrence of spark scratches and the frequency of occurrence of unevenness of descaled skin was examined. FIG. 3 shows the results. Distance (y): 25-1
At 00 mm, little or no sparking occurred, and no scaled skin unevenness occurred at all. However, when the thickness was less than 25 mm, the frequency of sparking was high. In FIG. 3, a negative value of the distance (y) means that the entry roll (3) is immersed in the salt bath.

(Effects of the Invention) According to the method for descaling a titanium plate according to the present invention, a spark phenomenon based on contact between the immersion exit roll and the titanium plate without causing a reduction in roll life and a significant decrease in economic efficiency. And spark flaws can be prevented. Therefore, it is possible to prevent the yield of the titanium plate from being reduced due to the occurrence of spark flaws.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an outline of a descaling state of a titanium plate according to Example 1, FIG. 2 is a side sectional view showing an outline of a descaling state of a titanium plate according to a conventional method, and FIG. Shows the relationship between the distance between the lowermost part of the immersion exit roll and the salt bath liquid level in descaling of the titanium plate according to Example 1, the frequency of occurrence of spark scratches, and the frequency of occurrence of unevenness of descaled skin. FIG. (1) Titanium plate, (2) Introduction roll (3) ... Immersion entry roll, (4) ... Immersion exit roll (5) ... Derivation roll, (6) ... ... Salt bath

Claims (3)

(57) [Claims] An immersion inlet roll that moves up and down on the titanium plate entry side of the salt bath while running the titanium plate, and an immersion exit roll that moves up and down on the titanium plate exit side of the salt bath. In a method of descaling a titanium plate in which the plate is pressed from above and descaled by successively immersing in a salt bath, the liquid level height of the salt bath is detected, and according to the liquid level, the immersion is performed. At least the lowermost part of the entry roll is adjusted to a position lower than the liquid level of the salt bath,
A descaling method for a titanium plate, wherein a lowermost portion of the immersion delivery roll is adjusted to a position higher than a liquid level of a salt bath. 2. The angle between the titanium plate running between the immersion entry roll and the exit roll and the liquid surface of the salt bath is adjusted by adjusting the positions of the immersion entry roll and the exit roll. The method for descaling a titanium plate according to claim 1, wherein the control is performed at a temperature of about 3.0 degrees. 3. The distance in the titanium plate running direction of the non-immersed part of the titanium plate between the immersion entrance roll and the exit roll, is 500 to 2 mm.
The descaling method for a titanium plate according to claim 1, wherein the distance between the lowermost portion of the immersion delivery roll and the liquid surface of the salt bath is adjusted to 25 to 100 mm while adjusting the thickness to 000 mm.