JPS61217532A - Preventive against seizing of steel strip and method for preventing seizing - Google Patents

Abstract

PURPOSE:To prevent the seizing of a steel strip at a low cost by sprinkling a specified amount of starchy powder on the surface of the steel strip, coiling the steel strip, and annealing, it. CONSTITUTION:Starchy powder is sprinkled on the surface of a steel strip before annealing by 10-120mg/m<2>, preferably 10-40mg/m<2>, and the steel strip is coiled and annealed. The starchy powder is preferably produced by adhering silicone resin on cornstarch or potato starch to about 0.5-3mum thickness per one starch particle. The seizing of the steel strip is prevented without deteriorating the surface properties.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an anti-seize agent and a method for preventing seizures that occur when batch annealing steel strips such as cold-rolled materials.

BACKGROUND OF THE INVENTION After being wound into a coil, cold rolled steel strip is generally subjected to batch annealing to improve its mechanical properties. During this annealing, Fe atoms between the steel strips are activated by the annealing temperature and move through the small gaps between the steel strips by diffusion.
As a result, a so-called seizure phenomenon occurs in which the steel strips adhere to each other.

The degree of this seizure phenomenon varies depending on the following factors.

(1) Annealing temperature: The higher the temperature, the more Fe atoms are activated and seizure occurs.

(2) Coil winding tension When the tension increases, the contact pressure between the steel strips in the coiled state increases, and seizure is likely to occur.

+31 @ Cloth surface roughness: The smaller the surface roughness, the smaller the gap between the steel strips and the easier it is to seize. This tendency is particularly strong for steel strips with prite specifications that have a small surface roughness.

(Cross-sectional profile of 41w4 strip: If there is an abnormal protrusion in the widthwise profile of the steel strip due to abnormal wear of the rolls of a hot rolling mill, etc., the coil surface pressure will concentrate on that part and seizure will occur.

Therefore, conventionally, countermeasures have been taken to reduce the occurrence of image sticking due to the above-mentioned factors. However, in that case, the following problem arises.

When the tll annealing temperature is lowered, the mechanical properties of the cold rolled steel strip deteriorate and the workability deteriorates.

(2) When the coil winding tension is lowered and the surface pressure is reduced, the coil itself is easily deformed, and flaws are likely to occur due to winding misalignment during unwinding in the next step.

(3) Although seizure can be prevented to some extent by increasing the surface roughness of the steel strip, the excessive surface roughness remains even after annealing and pressure adjustment, and the surface quality deteriorates. This tendency is particularly noticeable in the case of prite specifications. Furthermore, it becomes difficult to maintain the roll surface roughness during cold rolling.

(4) Although it is important to prevent abnormal protrusions in the cross-sectional profile of the steel strip, this requires increasing the frequency of replacing work rolls in the hot rolling mill, which leads to a decrease in efficiency.

For the above reasons, sufficient anti-seizure effects could not be obtained by taking measures against the factors (1) to (4).

On the other hand, as another means to prevent seizure of the steel strip during batch annealing, an aqueous suspension, especially a colloidal solution, of metal oxides such as alumina, silica, titania, etc. is applied to the steel strip before annealing.
A method of drying, winding and annealing is conventionally known. For example, JP-A-58-126934 and JP-A-58-141339 disclose the use of an alumina-based colloidal solution to prevent seizure of steel strip in this manner.

In this case, although a certain degree of anti-seizure effect can be obtained due to the action of alumina, etc., it is actually difficult to achieve a coating amount sufficient to fully exhibit the anti-seize effect. The reason for this is that since the colloidal solution is applied and squeezed with a ringer roll and then dried, the amount of adhesion after passing through the ringer roll becomes a very small value. Therefore, even with the use of overcasting means, a sufficient anti-seizure effect could not be obtained.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, instead of using an anti-seize agent applied in the form of an aqueous colloid solution as in the past, a powdered anti-seize agent is used. The agent is sprayed and adhered to the steel strip in a dry state before annealing, and then the steel strip is wound into a coil and annealed.

The present inventors have discovered that a starchy powder, preferably a starchy powder whose surface has been treated with a silicone resin, is suitable for this purpose, and have completed the present invention.

Here, the present invention is an anti-seize agent for steel strips comprising starchy powder.

According to another feature of the present invention, the present invention provides a method in which starchy powder is sprinkled on the surface of the steel strip before annealing in an amount of 10-120 tag/I, the steel strip is wound into a coil shape, and the annealing is performed. This is a method for preventing seizure of steel strips.

(effect) The present invention will be explained in more detail below.

The anti-seize agent used in the present invention is a starchy powder. This powder is preferably one in which the periphery of the starchy particles is coated with a silicone resin surface treatment in order to improve dispersibility, but untreated starchy powder can also be used. The particle size of the starchy powder is preferably 100μ or less, and if the particle size exceeds 100μ, it becomes difficult to adhere uniformly. The preferred particle size range is 5 to 5
It is 0μ.

The starchy powder may be, for example, potato or corn starch. The surface treatment of this starch powder can be carried out by adsorbing a silicone resin to a thickness of about 0.5 to 3 μm per starch particle.

The amount of starch powder to be sprayed is not particularly limited, but is generally preferably within the range of 10 to 120 B/rd. The reason for this is that according to the experimental results of the present inventors, which will be described in the Examples below, as shown in FIG.
If it exceeds rrf, a sufficient anti-seizure effect can be achieved, but starch will carbonize during annealing, resulting in black stains as smudges on the steel plate. A more preferable application amount is in the range of 10 to 40 ag/rrr.

Although the method of spraying is not particularly specified, for example, as shown in FIG. 2, the anti-seize agent of the present invention can be sprayed onto the steel strip 1 on the exit side of the cleaning line, just before the winder, using a powder sprayer 2. The specific structure of the spreader 2 is, for example, a third
As shown in the figure, it may consist of a combination of a roll feeder 3 and an electrostatic adder 4. The roll feeder 3 includes a guide plate 5, a roll 6, and a roll rotation motor 7. According to this device, the powder stored in the hopper formed by the guide plate 5 is cut out little by little by entering the recesses of the roll as the roll 6, which has an uneven surface, rotates and is carried downward. The powder that has reached the lower side is charged by an electrostatic adder 4, dropped onto the steel strip 1, and adsorbed. In this way, the starchy powder can be evenly distributed. In this case, the amount of powder to be spread can be easily adjusted by changing any one or more of the rotation speed of the roll, the gap between the roll and the guide plate, the roll surface roughness, the voltage of the electrostatic adder, etc.

The anti-seize agent made of starchy powder of the present invention has 9
It can be used for annealing at temperatures up to about 00°C.

The invention will now be illustrated by examples.

(Example) As an anti-seize agent, starch powder with a particle size of 10 to 20μ that had been surface-treated with a silicone resin (trade name Ninikkariko) was used, and was sprayed in various amounts using the spraying device shown in Figure 3. Thereafter, it was wound into a coil and batch annealed. This starch was obtained from potatoes, and the silicone resin coating with a thickness of about 1 μm was formed on the surface of the starch particles. The steel strip used was manufactured by cold rolling, with a thickness of 0.5 mm and a width of 1000 mm.
The steel strip was made of low carbon guild steel with a bright surface finish, and was wound with a tension cover turn as shown in FIG. The amount of spraying was adjusted by adjusting the voltage of the electrostatic adder and changing the amount of spraying according to the relationship between voltage and amount of spraying shown in FIG. Annealing was performed at 680°C for 18 hours.

After batch annealing at 680°C for 18 hours, the degree of seizure was evaluated based on the loudness of the seizure noise generated as the seized steel strip peeled off during unwinding with a payoff reel during pressure regulation, and the spray amount and anti-seizure effect were evaluated. We investigated the relationship between

The results are shown graphically in FIG. 1, and the coil with the spray amount O produced a loud seizure noise, and visual inspection on the inspection line also revealed surface flaws due to seizure. On the other hand, 10mg/++ of starchy powder? When sprayed in an amount greater than
As the amount of spraying increases, the seizure noise also decreases significantly, especially at 6 g/n? At the above amount of spraying, no surface flaws due to seizure were observed in visual inspection. However, when the amount of spraying was 120 mg/rrl, scratches occurred due to tight winding of the coil, and the surface quality could not be ensured.

Next, the application amount is 50+mg/rd and 10(ll1g
/rrr, and the coil winding tension is 1.0 times, 1.3 times, and 1.0 times the tension cover turn shown in FIG.
The magnitude of the burning noise was compared when the winding was increased by a factor of 5. The results are shown in Figure 6. At a spraying rate of 5 tsg/rd, the seizure noise increases as the winding tension increases, but at a spraying rate of 100 tsg/rd, the winding tension increases by 1.5 tsg/rd. Even when the amount was doubled, the burn-in sound did not increase at all.

In addition, the anti-seize agent of the present invention is sprayed and wound into a coil,
Cold-rolled steel sheets manufactured by batch annealing were examined by rust prevention tests, chemical conversion treatment tests, and smudge evaluation tests, and they were found to be completely equivalent to normal cold-rolled steel sheets that were batch-annealed without using anti-seizure agents. It was at the level.

(Effects of the Invention) As explained above, the anti-seize agent and method of the present invention can achieve excellent anti-seize effects without impairing the surface properties of cold-rolled products. In addition, the starch powder used as an anti-seize agent in the present invention has a basic unit per unit weight of about 115% compared to alumina and silica.
Since it is a very inexpensive material of about 0, it can be manufactured at a much lower cost than anti-seize agents made of alumina, silica, etc. Furthermore, since it uses a solid powder, it can be used more easily than conventional anti-seize agents that require application and drying of an aqueous solution.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the amount of starch powder sprayed and the noise of the seizure. Figure 2 is a schematic perspective view showing the method of spraying the anti-seize agent of the present invention. Figure 3 is the anti-seize agent of the present invention. A schematic cross-sectional view of a spraying device that can be used to spray the agent; FIG. 4 is a graph showing the winding tension cover turn in the example; FIG. 5 is a graph showing the relationship between the voltage of the electrostatic adder and the amount of spraying; FIG. 6 is a graph showing the relationship between winding tension and seizure noise. 1: Steel strip 2: Powder spray amount 3:
Roll feeder 4: Electrostatic adder 5 Ni guide slope
6: Roll Figure 1 1; Noshi 1 = (m♀i 6 Figure 2 Figure 3 Figure 1: aIIi? Figure 4 A) and Table 1 Island Figure 5 Figure 6 Figure 1.0 1 ,3 1.5

Claims (3)

[Claims] (1) Anti-seizure agent for steel strips consisting of starchy powder. (2) The anti-seize agent for steel strips according to claim 1, wherein the starch powder is surface-coated with a silicone resin. (3) Add 10% starch powder to the surface of the steel strip before annealing.
A method for preventing seizure of a steel strip, which comprises spraying the steel strip in an amount of ~120 mg/m^2, winding the steel strip into a coil shape, and annealing the steel strip.