JPH09150363A - High specular polishing method and high specular polishing fluid for stainless steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the expense required for maintenance of a polishing device and its peripheral equipment without worsening polishing ability and polishing quality, by simultaneously employing chemical and mechanical polishing. SOLUTION: A polishing fluid, dispersing an abrasive grain of superfine grain size as an abrasive presenting mechanical polishing action by 50 to 100g/l concentration in an oxalic acid water solution of 1 to 10% concentration presenting chemical polishing action, is prepared. This polishing fluid is used for specular polishing of stainless steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method and a polishing solution for finishing the surface of stainless steel into a highly mirror-finished surface.

[0002]

2. Description of the Related Art In mirror finishing of stainless steel, cup type polishing using a polishing liquid in which abrasive grains such as alumina are dispersed in an aqueous nitric acid solution is used in order to obtain a high-gloss mirror-finishing quality without polishing scratches. The method has been adopted. Nitric acid, a chemical of the polishing liquid used, is highly corrosive to metals and the human body. Therefore, the cost of managing the polishing device and the scattering to the human body, the corrosion prevention maintenance of the polishing liquid tank, and the like are high, and the total polishing cost is very high. Electropolishing is also used as a means for obtaining a high mirror surface, but the polishing cost is similarly high due to the control of electrolysis conditions, control of electrolytic solution, and treatment. Buffing using chrome oxide or alumina-based abrasives has also been investigated, but buffing has a high efficiency in removing polishing streaks on the front polishing surface, but it is unique compared to the above two polishing methods. There is a drawback that vertical stripes and flaws are easily formed. Furthermore, since the surface quality is not stable, high quality mirror polishing cannot be obtained, and it cannot be applied to an article requiring a high mirror surface.

[0003]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem, and by using chemical polishing and mechanical polishing together, stainless steel can be provided with a quality without polishing scratches and The purpose is to finish with a high mirror surface with excellent glossiness and to reduce the maintenance load of the polishing device and peripheral equipment against corrosion.

[0004]

The high mirror polishing method of the present invention exhibits a chemical polishing action in order to achieve its object.
50-100 g / l of ultrafine grained abrasive grains as an abrasive exhibiting mechanical polishing action in an oxalic acid aqueous solution of 10% concentration
It is characterized in that a polishing liquid dispersed at a concentration of is prepared and stainless steel is mirror-polished using the polishing liquid. The polishing liquid used in the present invention is obtained by dispersing and deflocating ultrafine particle abrasive grains at a concentration of 50 to 100 g / l in an oxalic acid aqueous solution having a concentration of 1 to 10%. As the abrasive grains, one kind or two or more kinds of white alundum, green carborundum, silica and the like are used, and those having a particle size of about # 4,000 to # 10,000 are preferable. As a polishing tool,
For example, as shown in FIG. 1, a resin sponge 1 made of a chemically resistant material is fixed to a polishing base 2 to be used. The sponge 1 is made of a resin having excellent chemical resistance such as polyurethane resin, polyethylene resin, chloroprene resin, etc., and the porosity, resin hardness, etc. are selected according to the state of the pre-polished surface. The surface of the stainless steel 5 is polished while supplying the polishing liquid 4 sent from the nozzle 3 to the surface of the stainless steel 5. As the stainless steel 5 to be polished, one that has been polished in advance with an elastic grindstone or the like is used, and the scratches remain on the polished surface.

[0005]

[Function] When the stainless steel surface is polished by using both chemical polishing and mechanical polishing, the polishing ability is comparable to that using a conventional nitric acid-based polishing liquid, and a high mirror surface is obtained. It is possible to remove polishing streaks generated by polishing.
Further, since the polishing liquid is a weakly acidic oxalic acid type, the corrosive action on the metal material is considerably lower than that of nitric acid which has been conventionally used as a chemical polishing liquid component. Therefore, the labor and cost for anticorrosion management and maintenance for the metal members of the polishing apparatus and its peripheral equipment are reduced by half. As a result, the cost required for equipment and the like is greatly reduced, and the stainless steel is highly mirror-finished at a low polishing cost in total.

[0006]

【Example】

Example 1 An example in which stainless steel is highly mirror-polished will be described. It should be noted that stainless steel, which is the material to be polished, has a piece of SUS30 having a rectangular cross section of 40 mm and a length of 200 mm.
A 4 stainless steel square pipe, which had been pre-polished with a # 3,000 elastic grindstone, was used. In the pre-polished state, many polishing streaks remained on the stainless steel surface. As a polishing tool, sponge 1 of polyurethane resin is used
A cylinder having a diameter of 00 mm and a thickness of 20 mm was cut out and adhered to the polishing base 2 made of acrylic resin. The polishing liquid was prepared by diluting oxalic acid with tap water to a concentration of 1 to 2%, and further mixing and dissolving white alundum (WA) with a particle size of # 6,000 as polishing abrasive grains at a ratio of 25 to 200 g per liter of an aqueous oxalic acid solution. Prepared by gluing. Then, as shown in FIG. 1, the polishing tool is rotated and advanced,
An arbitrary amount of polishing liquid 4 was dropped during polishing. Regarding the composition of the polishing liquid, the relationship between the oxalic acid concentration and the WA concentration and the number of passes necessary for removing the scratches on the pre-polished surface was investigated. Rotation speed 300 rp
m, feed rate of 1,000 m / min, pressing amount per pass of 1 mm / pass acted as polishing conditions, various levels of the composition of the polishing solution were changed, and the influence of the composition of the polishing solution on the removal of streaks was investigated. . The effect of oxalic acid concentration was investigated at a constant WA abrasive concentration of 75 g / l. As shown in Table 1 showing the survey results, the oxalic acid concentration with a high streak removing ability is 1 to 1
It was 0%.

[0007]

The effect of WA concentration was investigated by varying the WA concentration in the range of 25 to 200 g / l under the condition that the oxalic acid concentration was kept constant at 1%. As can be seen from the survey results in Table 2, at a WA concentration of 100 to 200 g / l, the streak removing ability was high, but the tendency to generate microscopic flaws was strong. The area where the scratch removal ability is high and a polished surface with good surface quality is obtained is 50 to 100 g.
/ L.

[0009]

It can be seen from Tables 1 and 2 that there are suitable regions for both the oxalic acid concentration and the WA concentration. In order to understand the polishing ability in this polishing liquid composition region, a comparison was made with a nitric acid-based polishing liquid that has been conventionally used for chemical polishing. Polishing conditions are as follows: chemical concentration of oxalic acid or nitric acid is 1%, WA concentration is 75 g / l,
The cup-shaped polyurethane resin sponge tool shown in FIG. 1 was rotated at 300 rpm, and the feed rate was 1,000 mm / min.
The stainless steel was polished at a pressing amount of 1 m / pass per pass. The polishing ability at this time is shown in comparison with Table 3. From Table 3, about 5 passes were required for both the polishing liquid according to the present invention and the nitric acid-based polishing liquid in order to remove the # 3,000 pre-polished surface. That is, it is understood that the polishing liquid of the present invention has polishing ability comparable to that of the conventional nitric acid-based polishing liquid.

[0011]

Further, the surface roughness of the polished surface polished using each polishing liquid was measured. Table 4 showing the measurement results
, No difference is detected between the two,
High specular R _{ma x} = 0.1 [mu] m level were obtained. From the above results, it can be said that the oxalic acid-based polishing liquid of the present invention is comparable to the nitric acid-based polishing liquid in both the streak removing ability and the polishing surface quality.

[0013]

Next, the effect of the use of the oxalic acid-based polishing liquid on the reduction of maintenance of the apparatus was investigated as follows. That is, focusing on the fact that the polishing head portion of the polishing apparatus is a metal member in which a particularly corrosive environment is present and high strength is required, a comparative test was performed on the replacement intervals of the polishing heads. As can be seen from the test results in Table 5, the replacement interval of the polishing head using the oxalic acid-based polishing liquid was about one year, while the replacement interval of the polishing head using the nitric acid-based polishing liquid was about half. It was only 6 months. It is considered that this relationship also applies to other than the polishing head member in which the metal member is used. From this, it can be said that the maintenance cost when using the oxalic acid-based polishing liquid is about half that of the conventional one. Therefore, according to the present invention, it was confirmed that the cost required for the maintenance of the polishing apparatus and the peripheral equipment can be reduced without lowering the polishing ability and the surface quality as compared with the conventional method using the nitric acid-based polishing liquid.

[0015]

Example 2: Material finish as B to be polished is B
Using a stainless steel plate of A, a comparative experiment was performed on the polishing ability between an oxalic acid-based polishing liquid and a nitric acid-based polishing liquid. The material to be polished was pre-polished with an elastic grindstone of # 400 to # 3,000. The polishing liquid contains oxalic acid or nitric acid at a concentration of 1
%, The WA concentration adjusted to 75 g / l was prepared. As the polishing tool, a polyurethane resin sponge 1 having an outer diameter of 150 mm was used. Rotation speed 30
0 rpm, feed rate 1,000 mm / min, pressing amount 1 m
The stainless steel plate was polished under the condition of m / pass. In addition,
The polishing tool was moved on the stainless steel plate 6 along the locus shown in FIG. 2, and the completion of the movement of all loci was counted as one pass. The polishing ability of the oxalic acid-based polishing liquid is shown in Table 6 in comparison with the polishing ability of the nitric acid-based polishing liquid. As shown in Table 6, the number of polishing passes required to remove the scratches on the # 3,000 polishing surface was 4 for both the oxalic acid-based polishing liquid and the nitric acid-based polishing liquid. Regarding the surface roughness of the polished surface, no difference was detected between the oxalic acid-based polishing solution and the nitric acid-based polishing solution as shown in Table 7, and the surface was finished to have a high mirror surface of R _max = 0.1 μm. From this, it was found that the oxalic acid-based polishing liquid of the present invention has the same polishing ability and polishing surface quality as conventional nitric acid-based polishing liquids even in the polishing of plate materials.

[0017]

[0018]

As described above, in the present invention, the chemical polishing action and the mechanical polishing action are effectively achieved by polishing using a polishing liquid in which oxalic acid and polishing abrasive grains are properly mixed. As compared with the nitric acid-based polishing liquid that has been developed and has been conventionally used for chemical polishing, it is possible to suppress adverse effects on the polishing apparatus and peripheral equipment without lowering the polishing ability and surface polishing quality. As a result, the cost required for the maintenance of the polishing device and peripheral equipment is significantly reduced, and low-cost polishing becomes possible.

[Brief description of the drawings]

FIG. 1 is a polishing tool used in Examples of the present invention.

[Fig.2] Trajectory of polishing tool when polishing stainless steel surface

[Explanation of symbols]

1: Resin sponge 2: Polishing base 3: Nozzle 4: Polishing liquid 5: Stainless steel 6: Stainless steel plate

Claims (2)

[Claims] 1. A polishing liquid prepared by dispersing ultrafine abrasive grains at a concentration of 50 to 100 g / l as an abrasive having a mechanical polishing action in an aqueous solution of oxalic acid having a chemical polishing action and having a concentration of 1 to 10%. A high-mirror-polishing method and a high-mirror-polishing solution for stainless steel, which are prepared and mirror-polished for stainless steel using the polishing solution. 2. A stainless steel in which 1 to 10% concentration of oxalic acid aqueous solution exhibiting a chemical polishing action is dispersed with ultra fine grain abrasive grains at a concentration of 50 to 100 g / l as an abrasive exhibiting a mechanical polishing action. Polishing liquid for high mirror finish.