JPH0583639B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention aims to shorten the time until descaling and clean the coil surface after pickling when removing scale generated on the surface of a wire coil by pickling. The present invention relates to a pickling method and a pickling device that add ultrasonic vibration. [Prior Art] Conventionally, methods using ultrasonic waves have been widely used for general cleaning of steel materials for a long time. Particularly in degreasing and water washing processes, alkaline aqueous solutions and organic solvents are used as detergents, and these solutions and Ultrasonic vibration is often used in combination with Pickling with hydrochloric acid, sulfuric acid, etc. is also used as a method for descaling the surface of steel materials, and a method of adding ultrasonic vibration is also used for the purpose of improving descaling performance. For example, JP-A-50-57924 and JP-A-50-
Publication No. 61868 discloses a method of applying vibration directly to an object to be cleaned by bringing an ultrasonic transmitter into contact with the object,
No. 84385 discloses a method of providing an ultrasonic cleaning tank between pickling tanks, and JP-A-61-235584 discloses a method of applying ultrasonic waves during pickling of hot steel sheets with poor descaling properties. JP-A No. 61-279311 discloses a method in which a hot-rolled steel sheet is strained in advance and ultrasonic waves are applied during pickling; Various methods have been proposed, including a descaling method consisting of a step of applying sound waves and rapid cooling, and a subsequent step of pickling. Generally, the vibrators used for ultrasonic cleaning are immersion type,
A bottom-mounted vibrator or a focusing type vibrator with a vibration transmission horn is used, and various cleaning processes and cleaning devices are used depending on the purpose of cleaning. In addition, depending on the shape, size, and quantity of the items to be cleaned, the ultrasonic irradiation method in the cleaning tank may include irradiating from the bottom, side, top and bottom, shaking the items up and down, rotating, etc.
Methods such as moving it on a conveyor are used. In addition, a method of pickling wire coils evenly without applying ultrasonic vibration was developed in 1983.
No. 20358 discloses a method in which the coil is vibrated up and down and rotated in the circumferential direction of the coil. [Problems to be Solved by the Invention] Ultrasonic cleaning using the conventional method described above can be an effective means when the object to be cleaned is relatively small and many objects are to be cleaned at once. However, when the object to be cleaned is large and a large volume is used for cleaning, for example, when hot-rolled steel plate coils or wire rod coils are descaled by pickling while coiled, ultrasonic vibration There are very difficult problems in adding and maximizing its effects. First, the immersion type vibrator installed in the pickling tank must of course be made of acid-resistant material.
Furthermore, the bottom type, which is attached to the bottom outer wall of the cleaning tank and vibrates the cleaning liquid indirectly, cannot be applied to a pickling tank made of hot acid-resistant bricks and rubber lining. Second, since the effective irradiation area of the ultrasonic vibrator is limited, a large number of vibrators are required to apply ultrasonic waves to the entire object to be cleaned, which has a wide area. Third, there is a large volume of acid solution in a large volume pickling tank, and in a vibrator installed deep in the liquid, the ultrasonic waves are attenuated greatly due to water pressure, and due to standing waves from the liquid surface. The vibration effect also becomes weaker. As mentioned above, there is no good way to solve the problems, and until now there have been few practical applications of adding ultrasonic vibration to wire coils during the process of pickling them in coiled form. I can't. In the conventional method, in which the vibration transmitting horn is brought into direct contact with the object to be cleaned, the vibration effect is localized and cannot be spread over the entire object using a wire coil. In addition, most pickling of steel plates involves passing the coil through the tank while unwinding the coil.
This is also done with a single wire coil, but it takes more time than doing it in a coiled state. Regarding other methods using a coiled wire, when a vibrator is installed in the washing tank, compared to the normal case where no ultrasonic waves are applied, the effect is seen, albeit to a small extent, in areas close to the vibrator. It is local. This is because the vibration effect is extremely different depending on the installation position of the vibrator and the water depth, so the relationship between the amount of water, the installation position of the vibrator, and the distance from the object to be cleaned must be clearly determined in the cleaning tank. I can't find the example shown. The present invention solves the problems of the conventional methods described above, and greatly expands the scope of application of ultrasonic cleaning, which has been limited to relatively small objects to be cleaned, such as cleaning precision metal parts. It is something. [Means for Solving the Problems] Hereinafter, pickling of a wire rod coil wound into a coil after hot rolling will be described as an example. Scale is formed on the surface of steel wire coils, and in order to remove this scale,
Pickling is being carried out. Acids used for pickling generally include hydrochloric acid and sulfuric acid, and hydrochloric acid has a concentration of 5 to 25
%, temperature, room temperature to 40℃, concentration of sulfuric acid 5 to 30%,
It is usually processed at temperatures between 50 and 98 degrees Celsius. The wire coil is hung in its coiled form on a hanger and immersed in an acid solution in a pickling tank.The scale is dissolved and peeled off in the acid solution, and the scale is completely removed. It is lifted up and moved to the next process, such as washing with water. Descaling by pickling is
This is a removal and cleaning effect caused by a chemical reaction, and is influenced by the type, concentration, temperature, dissolved components, amount of inhibitor added, etc. of the acid solution. Ultrasonic vibration is used to promote this chemical cleaning action.
The aim is to create a synergistic effect between the dissolution reaction between steel and scale and the acid, as well as the physical impact effect of ultrasonic waves. Conventionally, the objects of contamination when cleaning steel surfaces are a mixture of oily substances such as oil, grease, various machine oils, and antirust oils, as well as mud, dust, and the like.
In addition to aqueous alkali solutions and aqueous surfactant solutions, various organic solvents are used as degreasers and detergents. For this kind of cleaning, the method of adding ultrasonic waves has been used for a long time as a more effective cleaning method, and the material of the ultrasonic vibrator is mainly stainless steel because it is relatively easy to resist corrosion. A diaphragm made by Manufacturer is used. On the other hand, when applying ultrasonic waves during pickling, the immersion type transducer, in which the transducer is installed directly during pickling, must be made of acid-resistant material, and it must be affixed to the transducer. It is necessary to cover the entire vibrator, including the diaphragm, with an acid-resistant material, and there are many difficulties such as completely sealing the lead wire attachment part from the oscillator to the vibrator. Therefore, there are few cases where it has been applied to descaling large components such as wire coils by pickling, and most of the conventional applications are for washing with water or weak alkaline aqueous solutions where corrosion resistance is not a big issue. Most of them are. In the present invention, we first conducted a test using an acid-resistant ultrasonic transducer that can be used for long periods of time in pickling. We have found a solution. Generally, wire rod coils manufactured by hot rolling weigh 1 to 2 tons and have a coil outer diameter of 1200 to 1400 mm.
This wire coil is hung from a coil hanger 4 as shown in Figure 1, and placed in a pickling tank 1.
Soak in acid solution 2 to pickle. The wire coil 3 to be pickled is spread out on the coil hanger 4 before entering the pickling tank 1, so the wire coil width is 1500 to 3000.
In some cases, the length can be as long as mm, and many ultrasonic transducers are required to apply ultrasonic waves to this expanded wire coil area. For this reason, the number of transducers was set so that the length equal to the coil width could be irradiated, and the coil was rotated while keeping the transducers fixed to the entire surface of the coil. The coil can be rotated using a rubber roll drive roller 6 attached to the mounting table 7 of the coil hanger 4;
Alternatively, a method of rotating the coil intermittently by installing a tilting table 8 having an inclined surface large enough to allow the coil to roll in the tank shown in FIG. 2 and moving the coil suspended by the coil hanger 4 up and down, etc. applies. Conventionally, the immersion depth of the coil 3 in the acid solution 2 is determined by using a pickling tank with a depth at least equal to the outer diameter of the coil and an appropriate amount of acid solution, since the entire coil is completely immersed in the solution. I need. In a large-volume pickling tank, the installation position of the transducer for applying ultrasonic waves is extremely important, and the influence of the liquid depth is particularly large. When installed at the bottom of the deepest tank, the ultrasonic waves were significantly attenuated by the liquid pressure, and the additional effect of the ultrasonic waves was small. In the present invention, in order to reduce the attenuation of ultrasonic waves due to the depth of the liquid, the first method is to reduce the depth of the liquid in the pickling tank, and to reduce the immersion depth of the coil suspended in the coil hanger in the acid liquid. The depth range is between the depth where the inner diameter contacts the liquid surface and less than half the outer diameter of the coil. In addition, the installation position of the ultrasonic transducer is set at a maximum depth of 900 mm from the liquid surface based on the experimental results shown in Figure 3, and the shortest distance from the coil surface is 700 mm based on the experimental results shown in Figure 4.
It was found that the addition efficiency of ultrasonic waves is the best when the thickness is less than mm. The second method is to completely immerse the entire coil, as in the case of a conventional pickling tank. distance too
Ultrasonic waves are applied to the coil surface at a distance of 700 mm or less. [Function] The vibrator used for ordinary ultrasonic cleaning generally has a frequency of 28KHz and a power density of 0.5 to 0.5KHz when the purpose is to achieve the effect of cavitation.
A 1.0W/cm ² magnetostrictive vibrator is used,
The range in which the performance of the vibrator is effectively exhibited is limited by the liquid depth, the distance to the object to be cleaned, etc., as described above. The depth of the cleaning liquid is related to the immersion depth of the coil, and in the first method, if the coil immersion depth is less than the inner diameter of the coil in contact with the liquid surface, naturally some parts of the inside of the coil will not come into contact with the acid solution, making it impossible. When the depth is more than half the outer diameter of the coil, the coil hanger becomes immersed in the acid solution, which limits the way the coil can be rotated. When the transducer is installed at a liquid depth of 900 mm or more, the ultrasonic wave is attenuated greatly by water pressure, and when the distance from the wire coil surface is 700 mm or more, the added efficiency of the ultrasonic wave becomes small. In the second method as well, the optimal installation position of the transducer is determined depending on the reason, but in this method, the irradiation surface of the transducer with respect to the coil surface faces downward, so compared to the first method, the ultrasonic wave is Although there are no standing waves from the liquid surface, the additional efficiency of ultrasonic waves is high because the attenuation due to water pressure is small. The most preferable method for rotating the wire coil is as follows:
As shown in FIG. 1, about half of the wire coil 3 is immersed in the acid solution 2 and rotated by a drive roller 6 attached to the coil hanger 4. By this method, the coil hanger 4 is not immersed in the acid solution 2. Therefore, there is no dissolution and erosion caused by acid, and the life of the hanger is greatly extended. Furthermore, being able to visually observe the descaling status of the coil can be an extremely effective means for quality control. When pickling wire coils, the usual method is to cut the bands that bind the coils, spread the coils as much as possible, reduce the overlap between the wires, and immerse the coils in an acid solution. If there is a sufficient gap between the wires, there is no particular need to install a vibrator inside the coil. However, if the coil remains bundled, if the coil is thick, it is desirable to install it in a movable manner so that the vibrator can be inserted inside the coil. [Example] (Example 1) A hot rolled steel AISI8620 wire rod with a diameter of 6.0 mm was hung on a coil hanger as a wire rod coil with an outer diameter of 1400 mm, a width of 1500 mm, and a weight of 1 ton.
Depth 2500mm, width 2000mm containing hydrochloric acid with a liquid temperature of 30℃
immersed in a pickling tank with a length of 4000 mm. Inside the pickling tank, a high frequency output of 1.2KW, a frequency of 28KHz, a power density of 1W/cm 2 , and a high frequency output of 1.2KW, a frequency of 28KHz, and a power density of 1W/cm ² are coated with an acid-resistant film at a depth of 130mm from the liquid level and 300mm from the surface of the wire coil.
Three magnetostrictive vibrators with a size of 410 x 420 mm were arranged in the width direction of the coil, and the ultrasonic irradiation surface was set parallel to the wire coil surface. The immersion depth of the wire coil in the acid solution was set to 1/3 of the outer diameter of the coil, and at the same time as the immersion, the coil was rotated at a speed of 1 rotation per minute using a drive roller of a rubber roll attached to the coil hanger. 1 wire coil
After rotation, the vibrator was activated by an ultrasonic generator, and as a result of continuing for 6 minutes, the scale on the surface of the wire coil was completely removed, and a clean surface skin with no smut adhesion was obtained after pickling. Ta. Similar tests were conducted with different hydrochloric acid concentrations and temperature conditions, and with different steel types. In addition, as Comparative Example 1, a conventional method in which the entire wire coil was immersed in an acid solution and allowed to stand without applying ultrasonic waves was also conducted, and the results are shown in Table 1.

【table】

[Table] Evaluation of Smuts adhesion state on material surface after pickling
1... Significantly more, 2... Much, 3... Slightly more, 4...
Few, 5…almost none.
(Example 2) A hot rolled steel AISI9254 wire rod with a diameter of 14.0 mm was hung on a coil hanger as a wire rod coil with an outer diameter of 1350 mm, a width of 1500 mm, and a weight of 1 ton.
It was immersed in the same pickling tank as in Example 1, which contained hydrochloric acid at a liquid temperature of 60°C. In the tank, three ultrasonic transducers with the same specifications as in Example 1 were arranged at a depth of 200 mm from the liquid level and 250 mm from the surface of the wire coil, with the ultrasonic irradiation surface facing downward and the surface of the wire coil. It was installed parallel to the A slope with a slope is installed at the bottom of the tank, and the wire coil suspended from the hanger is rotated intermittently using the slope.
Ultrasonic waves were applied continuously to the wire coil. Three minutes after immersion in the acid solution, the scale was peeled off and a clean surface without smuts was obtained. Similar tests were conducted with different hydrochloric acid concentrations and temperature conditions, and with different steel types. Furthermore, as Comparative Example 2, a conventional method in which no ultrasonic waves were applied was also conducted and the results are shown in Table 2.

[Table] Evaluation of Smuts adhesion state on material surface after pickling
1... Significantly more, 2... Much, 3... Slightly more, 4...
Few, 5…almost none.
[Effects of the Invention] The present invention provides a method that can maximize the additional effect of ultrasonic vibration in pickling wire coils. Ultrasonic cleaning can now be applied to large wire coils while they remain coiled. Furthermore, descaling and smut removal by pickling can be carried out in a short time and extremely cleanly even on low alloy steel, which is said to be extremely difficult to remove under normal conditions. Even for ordinary carbon steel, the pickling time can be significantly shortened, making a significant contribution to improving the productivity of pickling work. Improved pickling properties enable continued use of acid solutions at low concentrations, widening the range of their use, and significantly reducing the amount of acid solutions used. Furthermore, even when the temperature of the acid solution is around room temperature, the pickling time is sufficiently short, and a large economical advantage can be obtained in terms of energy. The surface skin after descaled pickling is free of smut build-up as seen after conventional pickling and therefore requires special operations to remove smut, such as cleaning with high-pressure water jets or brushing. This eliminates the need for time-consuming operations such as cleaning, and the clean surface without smuts has an extremely excellent effect on quality improvement in the subsequent surface treatment process. Furthermore, since the coil hanger that suspends the wire coil is not directly immersed in the acid solution, it has the advantage that its lifespan can be significantly extended.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a method of pickling the wire coil of the present invention by applying ultrasonic waves while rotating it by a drive roller of a rotating device attached to a coil hanger. FIG. 2 is a cross-sectional view of a method of pickling by applying ultrasonic waves while rotating the coil on a tilt table in the pickling tank while hanging the coil. Figure 3 is a graph obtained from experimental results of the relationship between the distance from the acid solution level in the pickling tank to the ultrasonic vibrator and the descaling rate of the wire coil. FIG. 4 is a graph showing the relationship between the distance from the ultrasonic transducer surface and the attenuation rate of ultrasonic waves. 1... pickling tank, 1... acid solution, 3... wire rod coil, 4... coil hanger, 5... ultrasonic vibrator, 6... drive roller, 7... mounting table, 8... tilting table .

Claims (1)

[Claims] 1. In pickling wire coils in a tank, the acid liquid level is 900
1. A method for pickling a wire coil by ultrasonic vibration, characterized in that pickling is carried out by applying ultrasonic waves using an ultrasonic vibrator installed at a distance of within mm and at a distance of 700 mm or less from the surface of the wire coil. 2. Pickling of a wire rod coil is carried out by suspending the wire rod coil on a coil hanger having a drive roller, and applying an acid solution to a depth of 1/2 or less of the outer diameter of the wire rod coil from the depth where the lower end of the inner diameter of the wire rod comes into contact with the acid solution. 2. The method of pickling a wire coil using ultrasonic vibration according to claim 1, wherein the pickling method is carried out while rotating the wire coil in the circumferential direction while the wire coil is immersed in water. 3. A claim in which the pickling of the wire rod coil is carried out by suspending the wire rod coil on a coil hanger and intermittently rotating the wire rod coil on an inclined table provided at the bottom of the pickling tank by moving the coil hanger up and down. Item 1. A method for pickling a wire coil using ultrasonic vibration. 4. A pickling tank for pickling the wire coil, a coil hanger having a mounting table with a drive roller for rotating the wire coil in the circumferential direction, and an ultrasonic vibrator provided in the pickling tank. A pickling device using ultrasonic vibration for a wire coil, characterized in that: 5 A pickling tank for pickling the wire rod coil, a coil hanger for hanging the wire rod coil, and a tilt table for intermittently rotating the wire rod coil in the bottom tank of the pickling tank; A pickling device using ultrasonic vibration for a wire coil, characterized in that an ultrasonic vibrator is provided in a bath.