JPH10427A - Treatment method of inner surface of metal pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a fluoroplastic film to the inner surface of an inexpensive stainless steel pipe by cutting the inner surface of a metal pipe in a circular shape and further grinding the same to roughen the same and subsequently applying a pluoroplastic coating material to the roughened surface to bake the same to form a coating film and spreading the coating film by a roller to smooth the same. SOLUTION: The inner surface of a stainless steel seamless pipe is cut in a circular shape by using the cutting blade 4 of a counter boring head to cut the longitudinal wrinkles of the inner surface of the steel pipe to obtain a wrinkle free staianless steel seamless pipe 1'. The inner surface of this steel pipe 1' is ground by using a grinding member having CBN fixed thereto or a grinding fabrick having grinding particles such as alumina bonded thereto to be roughened to form a coating substrate having rough surface unevenness 11. A fluoroplastic coating material is applied to this substrate to form a fluoroplastic film 12 which is, in turn, smoothed by a roller 13 to form a smoothed fluoroplastic film. By this constitution, the inner surface of an inexpensive raw pipe can be accurately coated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a fluororesin film having excellent corrosion resistance, chemical resistance, and non-adhesion, which is used for piping of various manufacturing plants such as pharmaceuticals, foods, semiconductors, dyeing, chemical plants, and the like. The present invention relates to a method for treating the inner surface of a stainless steel tube combined with a surface layer, and a method for treating the inner surface of a stainless steel tube which can be electrolytically, chemically polished, or pickled at low cost and very efficiently.

[0002]

2. Description of the Related Art As a typical example of non-rusting steel, that is, stainless steel, for example, 18Cr-8Ni (that is, SUS304) will be described. It becomes a completely magnetic austenitic structure, and provides excellent corrosion resistance and maximum malleability. Usually, after the solution heat treatment, straightening and pickling are performed.

Conventionally, the most basic types of stainless steel pipes are roughly classified into two types. One of them is a stainless steel seamless pipe made by cutting a round bar into a tube, and the other is one. First, there is a stainless steel welded steel pipe manufactured by bending a cut strip-shaped plate into a cylindrical shape, and then welding the joint by arc welding or electric resistance welding under an atmosphere of argon gas.

[0004] As shown in Fig. 1, the original pipe of a stainless steel seamless steel pipe has corrugated irregularities on the inner surface of the stainless steel pipe continuous in the axial direction, that is, has many vertical wrinkles in the axial direction. Usually a polygonal inside diameter, about 6 in extreme cases
It is shaped like a square. On the other hand, as shown in FIG. 5, the original pipe of the stainless steel welded steel pipe has a welded portion formed with vertical streaks on the inner surface of the stainless steel pipe with projections of a weld bead continuously extending in the axial direction.

Since the inner surfaces of the stainless steel seamless steel pipe and the welded steel pipe are not circular as described above, there is a major drawback that mechanical polishing cannot be performed as they are. That is, even if the polishing is performed, only the convex portion is cut off, and the concave portion remains as it is.

[0006] Therefore, in order to mechanically grind a raw pipe having an inner diameter that is not circular, the raw pipe of the stainless steel seamless steel pipe and the welded steel pipe is usually cold drawn through a die and a plug to form the inner pipe. The outer surface is plastically deformed to a perfect circle. Then, even if austenite is formed by solution heat treatment due to the work hardening by this processing, it becomes martensite, and in order to return the generated martensite structure to the austenite structure, the aforesaid 1010 is formed again.
There is a major drawback in that the solution heat treatment of quenching after heating to at least ℃ must be expensive.

In addition, cold drawing of the above-mentioned stainless steel pipe is to finish a thick and thick raw pipe to a predetermined size by making it thin and thin, so that the yield is extremely poor. Has the disadvantage of being more costly.

In addition, the surface of the inner surface of the stainless steel tube is usually subjected to solution heat treatment and then pickling, so that not only scratches but also segregation of impurities and the like which are concentrated on the surface of the stainless steel tube. However, a large number of deep pinholes are generated by being dissolved in this pickling, but they cannot be removed and there is a major drawback that they remain as they are. Although it is the most inexpensive, it has a serious drawback that it cannot be used for piping of various manufacturing plants such as foods, pharmaceuticals, semiconductors, and dyes because precision finishing such as polishing the inner surface cannot be performed as it is.

On the other hand, there is electrolytic polishing as another important conventional method for treating the inner surface of a stainless steel pipe. The basis of this electropolishing is to smooth the surface of the workpiece by dissolving the fine convex portions more than the fine concave portions, and the main function is to gloss the surface. For this reason, usually, when performing this electropolishing, it is necessary to smooth the surface of the workpiece by mechanical polishing in advance. Specifically, Rmax15μ
Large irregularities such as m and Rmax 25 μm have 5 convex portions.
Although it becomes lower by about μm, the unevenness as a whole is left as it is.

Therefore, a stainless steel pipe having a surface roughness of Rmax 3 to 7 μm when subjected to cold drawing, solution heat treatment, and pickling is subjected to electrolytic polishing.
In order to achieve a smoothing of up to a maximum of 0.3 to 0.6 μm, in electropolishing requiring a large current, the time and cost required for polishing are enormous, and there is a large disadvantage that the cost is extremely high.

Therefore, in the case of mechanical polishing, that is, polishing using abrasive grains, at least the final finish is a # 400 polishing cloth and the surface roughness is Rma.
A stainless steel tube of x2.0-3.0 μm was desired.

Nevertheless, the cost of the electrolytic polishing of the inner surface of the stainless steel pipe is expensive mechanical polishing (# 80 →
The cost is more than twice the cost of (# 150 → # 320 → # 400 is required), so there is a major disadvantage that the total cost for mechanical polishing is 3 to 4 times that for mechanical polishing. .

[0013]

The problem to be solved by the present invention is to have a metal structure which is mass-produced and has already been subjected to a costly solution heat treatment, and has the most excellent corrosion resistance and chemical resistance. Inexpensive raw pipes of stainless steel seamless steel pipes and stainless steel welded steel pipes are used as they are. While taking advantage of this excellent metal structure, it is possible to remove vertical streaks and vertical wrinkles on the inner surface of the stainless steel pipe to make it circular, coat it with a fluororesin film, spread it with a roller, and smooth it. Is its primary purpose. Furthermore, conventionally there was a case where roller burnishing was performed after electrolytic polishing,
This is because the passivation film generated by electrolytic polishing
Rolling out with a roller causes innumerable cracks, further rubbing with a roller may peel off part of the passivation film, not only impairing corrosion resistance, but also causing considerable wear and tear of the roller. there were.

In contrast to the conventional mechanical polishing (which requires four processes), the process can be performed in one process by using a roller burnishing process, and the cost of electrolytic polishing is reduced by two due to its excellent smoothness. / 3 or less.

[0015]

Means for Solving the Problems The present invention basically comprises:
By cutting vertical wrinkles and vertical streaks on the inner surface of the stainless steel pipe into a circular shape, roughening the surface, and then combining the fluororesin with the rough surface irregularities, rolling the fluororesin film with a roller, This is achieved by compressing the fluororesin film of (1) to form a dense structure and smooth it.

More specifically, a stainless steel welded steel pipe which is inexpensive but cannot be used due to the presence of vertical streaks of the bead, has a uniform metal structure and is extremely safe with respect to pressure resistance and corrosion resistance, but can be used as it is because the inner diameter is hexagonal The method is to cut the inner surface of a stainless steel seamless steel pipe into a circular shape, thereby spreading the fluororesin film coated thereon with a roller and densifying it.

The fluororesin used in the present invention is not particularly limited, and includes various known fluororesins, and is not limited to the examples. Powders, dispersions, enamels and other paints all apply. Also,
Glass fiber, carbon fiber, carbon, alumina,
Silicon carbide, titanium carbide, molybdenum sulfide, and the like can be added, and pigments and other substances can be added as necessary. By blending these, it is possible to make use of the high heat resistance, corrosion resistance, water repellency, and non-adhesive properties of the fluororesin, while compensating for disadvantages such as low hardness and no adhesiveness.

The metal pipe is not limited to a stainless steel pipe, but may be a steel pipe, a copper pipe, an aluminum pipe, or another metal pipe. Further, electrolytic etching may be performed as a chemical roughening treatment for the inner surface of the metal tube. Examples of the electrolytic etching solution include a sodium chloride aqueous solution and an ammonium chloride aqueous solution. An appropriate amount of electricity is 10 to 30 clones / cm ² , whereby the surface roughness is R
max 3 to 10 μm or more, and the adhesive strength of the fluororesin film is further increased. In stainless steel, this electrolytic etching forms a passivation film on the surface to improve corrosion resistance.

[0019]

EXAMPLES The present invention will be described below in detail with reference to examples, but it goes without saying that the present invention is not limited to these examples. The counter boring head used in the embodiment is not limited to this, and is not particularly limited as long as the inner diameter of the metal pipe is cut and expanded.
That is, a cutter such as a drill having a blade by dividing the circumference into two or more equally may be used. The abrasive used for the grinding is not limited to the examples, but may be diamond, CBN (cubic boron nitride), silicon carbide, alumina, zirconia, or other objects depending on the purpose. The metal pipe of the embodiment is JISG3449.
SUS30 stainless steel pipe for piping limited to
4, a nominal diameter 32A and a nominal thickness schedule 40S, that is, an outer diameter × thickness × length (42.7 × 3.
A 6 × 4000) mm stainless steel seamless steel pipe and a stainless steel welded steel pipe were used. In this embodiment, the same components are denoted by the same reference numerals, and description thereof will be omitted.

[0020]

Embodiment 1 An embodiment will be described with reference to the drawings.
FIG. 1A is a perspective view of the stainless steel seamless steel pipe 1. This inner diameter is 35.5 mm, but is 0.2 to 0.1 mm.
Many large vertical wrinkles 2 of 5 mm are continued in the axial direction. This was cut with a cutting blade (bite) 4 of the counter boring head 3 in FIG.
Is cut, as shown in FIG.
A circular stainless steel seamless steel pipe 1 'having a length of 5 mm and no vertical wrinkles 2 is obtained. The cutting conditions at this time are a cutting speed of 120 m / min and a feed speed of 1 mm / rev. As a result, irregularities (byte) of Rmax 20 to 35 μm are formed. The head 3 has a cemented carbide guide 6 which receives a cutting reaction force so that the cutting tool 4 can be cut accurately and smoothly.
The cutting tool 4 is finely adjusted by the screw 7. The uneven shape generated by cutting the cutting tool 4 is not only extremely unfavorable as a base for painting, but also causes a burnishing effect by slightly crushing the tops of the protruding parts by the cemented carbide guide 6, which causes a burnishing effect. Honing is separately performed since the formation of the roughened surface required for the above is further hindered.
The resin guide 8 is provided so that the boring of the counter boring head is stably performed.

The stainless steel seamless steel pipe 1 ′
There is no significant work hardening due to cutting, and it maintains high corrosion resistance and chemical resistance performance as it is when the raw tube is subjected to solution heat treatment. The honing head 9 shown in FIG. 3 is inserted into the inner surface 5 of the cut stainless steel seamless steel pipe 1 ′, and the rotation speed is 1200 rpm and the feed speed is 800 mm / mi.
Grind with n. The honing head 9 is provided with a grinding member 10 on which # 120 diamond abrasive grains are electrodeposited. The inner surface of the stainless steel tube 1 ′ was cut and ground to form a roughened surface 11 having a Rmax of 10 to 20 μm on the inner surface 5.

The inner surface 5 is degreased, washed with water and dried to be cleaned, and then “Polyflon TF” manufactured by Daikin Industries, Ltd.
E tough coat enamel TC-7100 ”(hereinafter TC71
00) is applied so that the thickness after firing becomes 25 μm, and is preliminarily dried at 90 ° C. for 30 minutes.
Baking was performed at 0 ° C. for 30 minutes. As a result, a coating layer 12 of a 25 μm-thick fluororesin film was formed on the inner surface of the stainless steel seamless steel pipe 1 ′.

The fluororesin film 12 coated on the rough surface 11 of the inner surface 5 of the stainless steel seamless steel pipe 1 'has a roughness of Rmax 2 to 6 μm. There are many pinholes.

In this embodiment, the fluorine resin film 12
Are rolled by the roller 13 of FIG. At this time, the fluororesin film 12 is crushed at the convex portion and Rmax
In addition to being smoothed 14 to 0.3 to 0.8 μm, many pinholes are also crushed to reduce the number.

[0025]

Embodiment 2 Embodiment 2 has the same JI as Embodiment 1 shown in FIG.
This is a stainless steel welded steel pipe 15 for piping of S standard and the same dimensions, and a bead 16 formed by welding has a large vertical streak in the axial direction. This inner surface is cut into a circle with a counter boring head 3 set to have an inner diameter of 36.5 mm in the same manner as in the first embodiment.
Is removed.

In the same manner as in the first embodiment, the wheel 17 with the polishing cloth shaft to which # 80 alumina abrasive grains shown in FIG. 6 were adhered was rotated at 1500 rpm, and the feed speed was 1 m /
min., roughened surface irregularities are formed, cleaned, and then baked to obtain 25 μm thick “Polyflon TFE Toughcoat Enamel TC7800 (manufactured by Daikin Industries, Ltd.)” stainless steel welded steel pipe 15. Was preliminarily dried at 100 ° C. for 40 minutes, and then baked in an electric furnace at 380 ° C. for 13 minutes. As a result, a 25 μm-thick fluororesin film was formed as a coating layer on the inner surface of the stainless steel welded steel pipe 15.

The fluororesin film 13 coated on the inner rough surface of the stainless steel pipe 15 is usually made of Rm
There are irregularities of ax 3 to 6 μm and many pinholes.
Next, when this is rolled by a roller 13 as shown in FIG. 4, the fluororesin film 12 is smoothed to Rmax 0.2 to 0.7 μm and a number of pinholes are crushed to reduce the number thereof. .

[0028]

Embodiment 3 This embodiment is an example in which the same stainless steel seamless steel pipe 1 as in Embodiment 1 is machined. In this embodiment, the resin guide 8 of the counter boring head 3 is formed in the same shape as the resin guide 8 instead of the resin.
This is a ground member. Thereby, even if there is no honing head 9 provided with a separate grinding member, both cutting and grinding can be performed at once, and the base of the fluororesin coating can be formed.

When the counter boring head 3 is cut under the conditions of Example 1, that is, at a cutting speed of 120 m / min and a feed speed of 1 mm / rev, the inner surface 5 of the stainless steel pipe 1 ′ has a rough surface of Rmax 10 to 20 μm. The unevenness is formed at a time. This is degreased with caustic soda, washed with water and purified, and then DuPont's "Teflon F"
EP one-coat enamel 420-105 "was applied by baking to a thickness of 35 m, pre-dried at 70C for 20 minutes, and then baked in an electric furnace at 345C for 15 minutes. As a result, a fluorine resin film 12 having a thickness of 35 μm was formed on the inner surface of the stainless steel pipe 1 ′. This fluororesin film 1
No. 2 has irregularities of Rmax 3 to 7 μm. When this is rolled by the roller 13 in FIG. 4, the convex portion of the fluororesin film 12 is crushed, and the Rmax is 0.4 to 0.8 μm.
And smoothed.

[0030]

Embodiment 4 In this embodiment, the stainless steel tube treated with the fluororesin film of Embodiment 3 is rolled with the rollers shown in FIG. As the heating means, for example, means for heating in an oven can be exemplified. By this heating, the fluororesin film 12 is more efficiently and smoothly rolled, and Rmax 0.3 to 0.5 μm
And smoothed.

[0031]

Embodiment 5 This embodiment is an example of processing SUS304TBS (outer diameter × thickness × length 38.1 × 1.2 × 4000 mm) specified in JIS G3347 stainless steel sanitary pipe. Although this tube has been subjected to a solution heat treatment at 1010 ° C., the inner surface may not have a rough surface suitable for performing a fluororesin film coating treatment. For example, bright annealing performed under an inert gas. Also, even if pickling is performed after the solution heat treatment, if the finish is beautiful and there are few rough surfaces, or if the condition of the rough surface on the inner surface of the stainless steel pipe is not uniform, etc. To roughen the inner surface of the stainless steel pipe.

Since the stainless steel sanitary pipe of this embodiment is normally cold drawn through a die, the inner surface of the pipe is finished in a substantially circular shape, and the pipe is roughened without the counter boring. do.
In this roughening process, a tape-shaped polishing cloth 18 bonded with # 120 alumina abrasive grains shown in FIG. 7 is axially fixed to a rubber-made cocoon-shaped grinding body 19, and both ends 20. , 21
Is pulled by a wire 22, and is reciprocated in the axial direction and polished, so-called "vertical polishing", and the surface thereof is Rmax12 to
It was 20 μm.

This is degreased, washed with water, dried, and then subjected to “Teflon FEP One Coat Enamel 9” manufactured by DuPont.
54-103 ". "954-10
3 ”to a thickness of 30 μm,
After drying at 150C for 15 minutes, baking was performed at 260-270C for 20 minutes. The Empitz hardness at this time was 2 to 3H, and the surface roughness was Rmax 4 to 9 μm. This was spread lightly with the roller 13 of FIG. 4 to have an Rmax of 0.5 to 1 μm.

[0034]

Embodiment 6 The metal tube of this embodiment is a copper tube deoxidized with phosphorus.
It satisfies the standard of IS3300-C1220T-0 and measures 38.1 × 2.0 × 4000 (mm).
And cold drawn. This is fixed to a cocoon-shaped grinding body 19 by fixing a tape-shaped polishing cloth 18 to which # 100 alumina abrasive grains shown in FIG. 7 are adhered as in Example 5 and "vertical polishing" is performed. 20 μm
After the surface was roughened, a coating of “TC-7400” was fired and applied so as to have a thickness of 33 μm, preliminarily dried at 90 ° C. for 30 minutes, and fired at 180 ° C. for 30 minutes in an electric furnace.
At this time, the surface roughness of the fluororesin film 12 is Rmax
It was 3-6 μm. When this is spread by the roller 13 of FIG. 4, the Rmax is 0.4 to 0.8 μm.
m.

[0035]

[Embodiment 7] This embodiment is an example in which the same stainless steel pipe as that of Embodiment 1 is machined. In this embodiment, the coating treatment of the fluororesin film is not performed. Since the inner surface of the stainless steel pipe has a smaller amount of cutting than the counter boring, the inner surface after being machined with a reamer head that has a small unevenness and is finished precisely and is ground with a grinding member 8 of # 240, Rmax was 2 to 6 μm, but when this was further subjected to roller burnishing, a part of the convex part of the rough surface generated at the time of cutting, especially the top was peeled off by roller burnishing, and a fine Separate as dusty metal powder.

Most of this is washed and washed away by cutting water and separated, but a part of it is sometimes adhered to the inner surface of the stainless steel pipe by a roller and remains. The surface roughness at this time is Rmax 0.2 to 0.5 μm. This is degreased, washed and washed, and electropolished. An example of the electropolishing liquid is phosphoric acid 40-45%, sulfuric acid 34-37%, chromic acid 3-4%, temperature 60-80 ° C, current density 40-100A.
/ Dm ³ .

As a result of the treatment under the above conditions, the surface was electropolished to an Rmax of 0.1 to 0.2 μm.
The metal powder remaining on the inner surface of the stainless steel pipe by electrolytic polishing is dissolved and removed, and at the same time, the surface is smoothed and brightened. Further, by roller burnishing, it is possible to dissolve and remove a part of the work hardened layer formed on the outermost layer on the inner surface of the stainless steel pipe into martensite, and at the same time, it is possible to form a passivated film. This product is used as it is as an electrolytically polished product of stainless steel pipe.

[0038]

[Embodiment 8] In this embodiment, as in Embodiment 1, a stainless steel pipe which has been subjected to cold drawing to dimensions (42.7 × 3.6 × 4000 mm) and then subjected to solution heat treatment is used. It is. In this embodiment, the coating treatment of the fluororesin film is not performed. After the solution heat treatment, 4-7% of hydrofluoric acid, 10-20% of nitric acid, pickling at a temperature of 60-80 ° C., and the surface roughness of the inner surface after water washing is Rmax 3-6.
However, when this was further subjected to roller burnishing, the roughened surface of the passivation film generated by the solution heat treatment and pickling was smoothed to Rmax 0.3 to 0.8 μm by roller burnishing. You.

This is degreased, washed and washed, and then electropolished. An example of the electropolishing liquid is phosphoric acid 40-45%, sulfuric acid 3
4-37%, chromic acid 3-4%, temperature 60-80 ° C, current density 40-100 A / dm ³ . As a result of the treatment under the above conditions, the surface has an Rmax of 0.1 to 0.4 μm.
m was electropolished. In addition, by roller burnishing, part of the work hardened layer generated on the outermost layer of the inner surface of the stainless steel pipe has become martensitic,
At the same time as being able to be dissolved and removed, a more stable passivation film can be obtained. This is a stainless steel pipe electrolytically polished work as it is.

In the above description, an example in which electrolytic polishing is performed after roller burnishing has been described, but ordinary pickling at a lower cost may be performed. One example of conditions for pickling is hydrofluoric acid 5%, nitric acid 15%, and a temperature of 60 ° C.

[0041]

As described in detail above, according to the present invention,
Various effects can be obtained as listed below. 1. The most inexpensive and stable stainless steel pipe can be used. 2. The polygonal inner surface of the original tube is cut into a circular shape with higher precision than the drawing process. 3. By the cutting, impurities, scratches, pinholes, etc. on the inner surface of the original tube are almost removed. 4. Since the accuracy of the circular shape generated by the cutting is good and the roller rolling is performed smoothly, a good and smooth fluororesin film coating can be obtained. 5. By cutting after cutting, the bite (unevenness by the cutting blade) is averaged and uniform roughened surface is formed, and a suitable fluororesin film is obtained. 6. Cleaner and more productive than polishing with # 400 abrasive cloth (paper) with abrasive grains bonded. 7. By providing a grinding member on a member other than the cutting tool 4 of the counter boring head, for example, the resin guide 8, two ordinary processes can be performed in one process. 8. Since the inner surface of the metal tube directly subjected to roller burnishing has already been smoothed to Rmax 0.2 to 0.5 μm, it can be processed in a short time by electropolishing it, and the cost is 2/3 or less. And greatly reduced. 9. 50 ~
By performing the roller rolling while heating to 150 ° C., the fluororesin film is stabilized, the possibility of peeling is reduced, and the film is further densified and smoothed.

According to the present invention, as described above, the fluororesin film constituting the surface has a dense structure with its large roughened surface being extended, and the number of pinholes is drastically reduced to improve the corrosion resistance and improve the corrosion resistance. The surface becomes smooth and free of bacteria.

On the surface layer of the spread fluororesin film,
There are no scratches that are inevitably caused by machining, and it is finished with better smoothness than electropolishing, so non-adhesiveness equivalent to or close to expensive pure fluororesin is obtained, so drainage The number of times the inside of the pipe is cleaned well can be greatly reduced.

[Brief description of the drawings]

FIG. 1A is a perspective view of a stainless steel seamless steel tube raw tube. b is a perspective view of the counter-bored stainless steel seamless steel pipe.

FIG. 2 is a perspective view of a counter boring head.

FIG. 3 is a perspective view of a honing head and a diamond grinding member.

FIG. 4 is an explanatory diagram showing before and after rolling a baked fluororesin film with a roller.

FIG. 5 is a perspective view showing a bead of a stainless steel welded steel pipe raw tube.

FIG. 6 is a perspective view of a wheel with a polishing cloth shaft.

FIG. 7 is a perspective view showing a cocoon-shaped grinding body.

[Explanation of symbols]

 1. 1. Stainless steel seamless steel pipe 1 'Stainless steel seamless steel pipe whose inner surface is cut into a circle 2. Vertical wrinkles 3. Counter boring head Byte 5. Stainless steel pipe inner surface 6. Carbide guide 7. Screw 8. Resin guide 9. Honing head 10. Grinding member 11. Rough surface irregularities 12. Fluororesin film 13. Roller 14. 14. Smoothed fluororesin film Stainless steel welded steel pipe 16. Bead 17. Foil with polishing cloth shaft 18. Tape-shaped polishing cloth 19. Cocoon shaped grinding body 20. End of grinding body 21. End of grinding body 22. Wire 23. Winding roller

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[Procedure amendment]

[Submission date] August 9, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG. 1-a

FIG. 1-b

FIG. 2

FIG. 6

FIG. 3

FIG. 4

FIG. 5

FIG. 7

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location B05D 7/24 302 B05D 7/24 302L C23F 3/04 C23F 3/04 C23G 1/08 C23G 1 / 08 C25F 3/02 C25F 3/02 B

Claims (8)

[Claims] An inner surface of a metal tube is cut into a circle by a counter boring head, and the inner surface is ground with a diamond, CBN, or the like, or a polishing cloth bonded with alumina, silicon carbide, or other abrasive grains. A method for treating the inner surface of a metal tube, wherein a fluororesin-based paint is applied to the base of the coating formed by grinding and roughening, and then baked to form a coating film, which is spread by a roller and smoothed. . 2. The method according to claim 1, wherein the inner surface of the metal tube is cut into a circular shape, and the surface is ground or not by grinding or roughening with a fluororesin paint. The method for treating the inner surface of a metal pipe according to claim 1, wherein the coating is generated by firing, and the coating is spread and smoothed by a roller. 3. The method according to claim 1, wherein a coating film is formed by applying and baking, and the coating film is spread by a roller while being heated to 50 to 200 ° C. and smoothed.
Or the method for treating the inner surface of a metal tube according to item 2. 4. A diamond or CB guide for a counter boring head guide for cutting the inner surface of the metal tube into a circle.
2. The method for treating the inner surface of a metal tube according to claim 1, wherein abrasive grains such as N are fixed to form a grinding member, and are ground at the same time as cutting. 5. The method according to claim 1, wherein the metal pipe is a stainless steel pipe. 6. A counter boring head comprising a grinding member provided on said guide. 7. A solution-treated heat-treated stainless steel pipe is formed by cutting the inner surface of the pipe into a circular shape by counter boring or the like, and then smoothing by roller burnishing, and then subjecting the pipe to electrolytic polishing, chemical polishing, or acid polishing. A method for treating the inner surface of a metal tube, characterized by finishing by washing. 8. A stainless steel pipe having an inner diameter rounded by plastic working such as cold drawing is subjected to a solution heat treatment, and then the unevenness of the inner surface is spread and crushed by roller burnishing, and then smoothed. A method for treating the inner surface of a metal tube, wherein the inner surface is finished by electrolytic polishing, chemical polishing, or pickling.