KR20000040609A - Method for forming dimple on surface of cooling roll in twin roll type thin plate molding apparatus - Google Patents

Abstract

PURPOSE: A method for forming a dimple on the surface of a cooling roll is provided to minimize the irregular arrangement of a dimple and to maximize the dimple area within a short time. CONSTITUTION: A roll(1) surface is pre-treated, and the pre-treated roll surface is sprayed with a photo-sensitive solution(8) and is dried. An irregular ink droplet(111) is formed by spraying transparent ink on the rotating roll surface with a droplet spraying method. The transparent ink droplet is washed off after the surface is infrared ray-exposed, and the surface is developed with a development solution. The surface is etched by spraying an etching solution, and a film is removed with a basic solution so that the dimple is formed on the surface of the cooling roll.

Description

Dimple Formation Method on Cold Roll Surface of Twin Roll Type Sheet Casting Machine

The present invention relates to a method for treating the surface of the cooling roll of a twin roll type sheet casting apparatus for producing a thin plate by injecting molten metal between two cooling rolls and rapidly solidifying through contact with the roll, and more specifically, a photo etching method. The present invention relates to a method for forming a dimple on a surface of a cooling roll of a twin roll thin plate casting apparatus.

In general, a double roll type sheet casting apparatus is formed in a space formed by two rolls 1 and an edge dam 2 attached to a side of a roll through a nozzle 4 as shown in FIG. After supplying the molten steel pool 5 to form, the molten steel is rapidly solidified by heat flux to the inside of the roll through the contact between the roll and molten steel while rotating the roll 1 to produce the cast steel 6. Device.

Reference numeral 7 in Fig. 1 represents a guide roll.

Since the slabs manufactured as described above are thin slabs of about 2 to 6 mm, the solidification shell formed initially has a great influence on the surface properties of the slabs. The uneven thickness of the initial solidification shell solidified on the roll surface causes various defects such as surface cracks or overlapping defects on the surface of the manufactured cast steel and affects the final product.

In order to solve this problem, the technique which processes the numerous dimples 14 on the surface of a cooling roll is disclosed by Unexamined-Japanese-Patent No. 60-184449.

In Japanese Patent Application Laid-Open No. 60-184449 and the like, a gas gap, which is an insulating layer, is formed between the cooling roll and the solidification shell by dimples to reduce the heat extraction of the cooling roll so that the smoothing of the solidification shell is reduced. While inducing cooling, embossed dimples are formed on the surface of the slab, and solidification starts from the peripheral edge of the relief so that the thickness of the solidification shell is uniform in the plate width direction.

In addition, in order to effectively prevent surface cracking of cast steel, Japanese Patent Laid-Open Publication No. 64-83340, Japanese Patent Laid-Open No. 64-83342, and Japanese Patent Application Laid-Open No. 64-83340 describe the formation of dimples on the surface of a cooling roll and the size of dimples or the distribution of dimples. -110044 and the like.

As such, the surface state of the roll in direct contact with the molten steel in the twin roll type sheet casting device is a factor that greatly affects the quality of the cast steel. Therefore, the surface treatment of the roll which can effectively disperse the thermal stress of the cast steel is essential to produce a flawless cast steel. to be.

As an example of the conventional roll surface treatment technology, Japanese Patent Laid-Open No. 5-329585 is mentioned. Here, the surface of the roll is roughened by engraving by varying the pressure on the surface of the roll by mechanical processing (knurling) (Knurling).

However, it is difficult to form the roll surface irregularities having the desired dimensions and shapes by the knurling method, and also due to the constraint that the distribution of the irregularities in the roll width direction and the circumferential direction can not be arbitrarily improved, the proper unevenness forming conditions for the production of flawless cast pieces. Is difficult to derive, and the knurling method is not suitable as an effective roll surface treatment technique because it is easy to cause bumps and processing defects around the intaglio in addition to these problems.

In addition, laser processing or shot blasting is possible, but the laser processing method is not economical because of the long processing time and high processing cost, and the shot processing method can be inexpensively processed in a short time, but the wear resistance of the roll In the case of a roll material such as Cr, Co, etc., which are generally used as a plating layer material to improve, there is a problem in that it is difficult to form dimples of a desired depth because it is difficult to process the dimples by the shot processing method.

In addition, when processing the dimples by the shot processing method, in order to extend the life of the roll, the dimples must be deeply processed within a narrow range, and in general, the deeper the dimples are processed, the wider the distribution range of the depth is. Disadvantages in terms of roll life extension.

In order to solve this problem, the present inventors treat the surface of the roll in a specific form by a chemical corrosion method, so that the degree of freedom in forming the workpiece is large, so that any surface shape can be given, and the processing surface is beautiful due to chemical processing. In addition, it has been proposed a method that can process the surface of the roll economically with less processing time, which was filed in 1997 patent application No. 71245.

Surface treatment of the cooling rolls by the photo-etching technique as described above enables surface treatment to the target dimple size, distribution and depth relatively easily compared to the knurling, laser and shot processing methods.

However, as shown in Figure 2, when forming the dimple through the film masking process as described above, due to the linear defects of the joint portion 10 of the film 9, which is inevitably generated during the film masking process There is a problem that can cause cracking of the bias.

Of course, in order to minimize the above problems, film masking can be performed through several trials and errors, but the film masking process, which occupies most of the entire process, is repeated, which is very economically disadvantageous in terms of cost and processing time. Remaining.

In Fig. 2, reference numeral 8 denotes a photosensitive liquid applied to a roll surface, reference numeral 13 denotes a dimple formed on a masking film, and 14 denotes a dimple formed on a cooling roll surface.

On the other hand, in order not only to produce flawless casts, but also to prevent glossiness of casts, the diameter of the dimples can be solved by randomly dispersing the grains by randomly dispersing the diameter of 0.1 to 1.0 mm. 66460 and the like.

In addition, Japanese Patent Application Laid-Open No. 4-158957 discloses that in the case of austenitic stainless steel, which is a major steel grade in the sheet casting process, the closest distance between the dimples should be maintained at 350 µm or less to effectively alleviate the uneven solidification caused by the dimple irregularities. A method of reducing coagulation structure non-uniformity susceptibility is disclosed by uniformizing coagulation structure as a whole and at the same time maintaining the amount of delta ferrite at 5-9%.

As described above, in order to prevent defects from being cast or to fabricate tissue by providing dimples on the surface of the cooling roll, the effect may be maximized by minimizing the interval between dimples and irregularly distributing the dimples.

However, as shown in FIG. 2, when forming a dimple through film masking, a certain distance should be secured to prevent the occurrence of defects in the final seam when the film is cut and joined to both ends, and the film seam 10 is formed. ), The dimple pattern should have regularity to prevent line defects.

Therefore, a new dimple forming method must be devised because the film masking process cannot maximize the effect of dimple formation, that is, irregular dimple arrays, minimizing the distance between dimples, and maximizing dimple area. .

The present inventors have made a study to solve the above-mentioned problems of the prior art, and based on the results, the present invention is proposed, the present invention is an irregular arrangement of dimples formed on the surface of the cooling roll of the twin-roll type sheet casting apparatus The present invention aims to provide a dimple forming method on the surface of a cooling roll of a twin-roll thin sheet casting apparatus, which can economically achieve minimizing the distance between dimples and maximizing the dimple area in a shorter time.

1 is a schematic diagram of a general twin roll type sheet casting apparatus

Figure 2 is a process chart for explaining the dimple forming method of the surface of the cooling roll by the photo etching method through a conventional film masking process

3 is a process chart showing a method of forming dimples on the surface of a cooling roll according to the present invention.

4 is a schematic view showing an example of a droplet spraying device in accordance with the present invention;

Explanation of symbols on the main parts of the drawings

1 ... (Object) Roll 8 ... Photoresist 10 ... Joint 20 ... Droplet Sprayer

21 ... Spray roll 22 ... Spray brush 25 ... Flat knife

111 ... Ink Drops 112 ... Dimples

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is a method of forming a dimple on the surface of a cooling roll of a twin roll thin plate casting apparatus by a photo etching method,

Pretreating the roll surface;

Applying a photoresist to the pretreated roll surface and then drying;

After drying as described above, spraying opaque ink on the rotating roll surface (dry photosensitive liquid surface) by the droplet spraying method to form irregular ink droplets;

After the ultraviolet exposure treatment, washing the opaque ink droplets and then developing them with a developer;

Spraying etching liquid after the development is completed as described above; And

The present invention relates to a dimple forming method on a surface of a cooling roll of a twin roll thin plate casting apparatus comprising a step of removing the film with a basic solution.

Hereinafter, the present invention will be described in detail with reference to the drawings.

3 illustrates a process of forming a dimple according to the present invention, and the present invention will be described with reference to FIG. 3.

According to the present invention, in order to form dimples on the roll surface, the roll surface must be pretreated.

In the present invention, the surface of the target roll (cooling roll) 1 to form a dimple is sanded only in the circumferential direction with # 600 to 800 edge paper to impart roughness with the roll surface roughness Ra of 4 to 5 μm. It is preferable to perform pretreatment.

The reason for selecting the roll surface roughness as described above is to improve the adhesion of the photosensitive liquid applied to the roll surface to prevent film removal during the etching process.

Next, after apply | coating the photosensitive liquid 8 to the roll surface pretreated as mentioned above, it dries.

The photosensitive liquid coating is preferably uniformized to a thickness of 3 to 5㎛ by nozzle spraying, and naturally dried in a closed room in which light is blocked for about 1 hour.

Next, after drying as described above, opaque ink is sprayed on the rotating roll surface (dry photosensitive liquid surface) by the droplet spray method to form an irregular ink droplet 111, which will be described in detail with reference to FIG. Same as

Figure 4 shows an example of a droplet spraying device for implementing the dimple forming method of the present invention.

As shown in FIG. 4, the droplet spray apparatus 20 is sprayed toward the spraying roll 21, the spraying brush 22 attached to the surface of the spraying roll 21, and the spraying brush 22. And a spraying tank 23 configured to supply the spraying liquid, a flat knife 25 in contact with the spraying brush 22, and an upper and lower adjusting device 26 of the flat knife 25.

The spray tank 23 is provided with a flow rate regulator 24.

A method of forming the ink droplets 111 using the droplet spraying apparatus 20 configured as described above will be described.

The ink stored in the spray tank 23 is supplied toward the spray brush 22 which is rotated by the rotation of the spray roll 21 by controlling the flow rate by the flow regulating device 24 to spray the spray. The contact of the brush 22 and the flat knife 25 is applied onto the surface of the object roll 1 in the form of droplets and sprayed onto the dried photosensitive liquid.

The size or the total amount of the ink droplets 111 sprayed as described above is determined by the rotational speed of the object roll 1 and the spray roll 21, the contact length and the flow rate of the spray brush 22 and the flat knife 25, and the like. It is done.

In the present invention, by such an operation factor, the shape, size and density distribution of the dimples formed on the roll surface can be arbitrarily adjusted.

The spherical ink droplets 111 sprayed by the above method are attached to the photoresist 8 coating surface and spread to form circular or elliptical ink droplets 111.

In the present invention, the opaque ink used to form the dimple should have the property of blocking ultraviolet rays after drying, and in order to have a dimple shape circular or oval, an aqueous ink or an oil ink having a viscosity of 20-40 Ps is used. It is desirable to.

The viscosity of the ink can be adjusted by mixing a solvent as necessary.

After forming the ink droplets as described above, after exposure treatment with ultraviolet rays while rotating the roll on which the ink droplets are formed, the opaque ink droplets are washed and then developed with a developer.

It is preferable to perform the exposure treatment for about 15-20 minutes with an ultraviolet lamp.

The developer is preferably a developer for negative resist (TPR).

When exposed as described above and developed with a developing solution, the photoresist coated surface in contact with the ink droplets does not cause photolysis due to UV blocking, and when developed with a developing solution, only the contacting part melts and the other part is hardened by curing by photolysis. It is a protective film with oxidation resistance.

After the development is completed as described above, the etching solution is evenly sprayed and etched.

Next, dimples 112 are formed on the surface of the cooling roll of the twin roll thin plate casting apparatus by removing the film with a basic solution.

That is, after the etching is completed, it is preferable to perform film removal treatment of the cured negative resist as a protective film with a basic solution, preferably with a 10% NaOH solution.

As described above, the present invention can not only irregularly form the dimples of the desired particle size distribution in a short time, but also can minimize the distance between the dimples to maximize the effect of the dimple formation, and also maximize the dimple area ratio. Since it can be easily achieved, there is an effect that can be more effectively applied to the surface treatment technology of the cooling roll for sheet casting.

Claims (9)

In the method of forming a dimple on the surface of the cooling roll of the twin-roll thin plate casting apparatus by a photo etching method, Pretreating the roll surface; Applying a photoresist to the pretreated roll surface and then drying; After drying as described above, spraying the opaque ink on the surface of the rotating roll by the droplet spray method to form irregular ink droplets; After the ultraviolet exposure treatment, washing the opaque ink droplets and then developing them with a developer; Spraying etching liquid after the development is completed as described above; And Dimple formation method on the surface of the cooling roll of the twin-roll type sheet casting apparatus comprising the step of removing the film with a basic solution The cooling roll surface of the twin roll type sheet casting apparatus according to claim 1, wherein the pretreatment of the roll is performed to have a surface roughness Ra of 4 to 5 mu m, and the photoresist is applied to a thickness of 3 to 5 mu m. Dimple Formation Method The dimple forming method on the surface of a cooling roll of a twin roll thin plate casting apparatus according to claim 1 or 2, wherein the viscosity of the ink is 20-40 Ps. The dimple forming method on the surface of a cooling roll of a twin-roll thin sheet casting apparatus according to claim 1 or 2, wherein the exposure treatment is performed by an ultraviolet lamp for 15-20 minutes. 4. The method of forming dimples on the surface of a cooling roll of a twin roll thin plate casting apparatus according to claim 3, wherein the exposure treatment is performed for 15 to 20 minutes with an ultraviolet lamp. The method for forming dimples on the surface of a cooling roll of a twin-roll thin plate casting apparatus according to claim 1 or 2, wherein the film removal treatment is performed with a 10% NaOH solution. 4. The method of forming dimples on the surface of a cold roll of a twin roll thin plate casting apparatus according to claim 3, wherein the film removal treatment is performed with a 10% NaOH solution. 5. The method of forming dimples on the surface of a chill roll of a twin roll thin plate casting apparatus according to claim 4, wherein the film removal treatment is performed with a 10% NaOH solution. 6. A method of forming dimples on the surface of a cold roll of a twin roll thin plate casting apparatus according to claim 5, wherein the film removal treatment is performed with a 10% NaOH solution.