JPH09174414A - Barrel polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a corrosion problem of an acidic chemical abrasive material simultaneously with improvement of polishing efficiency as surface roughness is maintained at the same degree as ordinary one, reduce the occurrence of an adverse influence exercised by friction fine powder of media even during a heavy cutting work, and increase a grinding ratios of media to a comparatively a high value. SOLUTION: A compound containing 0.5-2wt.% a hydroxide of an alkali metal, for example, caustic soda, preferably further containing at most 5wt.% organic acid salts, for example, salts of gluconic acid, citric acid, and tartaric acid, and media are charged in a barrel polishing tank to polish a work made of aluminum or an aluminum alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barrel polishing method, and more particularly to a method for efficiently polishing a workpiece made of aluminum or an aluminum alloy and having a relatively complicated shape.

[0002]

2. Description of the Related Art Conventionally, a buffing method has been used to perform a grinding process for adjusting the shape of an aluminum or aluminum alloy work piece while maintaining the dimensional accuracy and a surface finishing process such as improving the surface roughness and gloss or gloss finish. And the barrel polishing method are used. In the buffing method, it is usual to use many types of buffs, ranging from coarse to fine abrasive grains attached to the buff, depending on the degree of finish, so it takes a lot of steps to process and When the shape of the object becomes complicated, there is a problem that skill is required and the number of steps is increased such that it is necessary to appropriately select and properly use a buff having a different shape depending on a polishing portion.

On the other hand, in the barrel polishing method, since the entire surface of the workpiece can be uniformly polished by selecting and using a medium having an appropriate size, normally, finishing processing can be performed in one or two steps. It is an efficient polishing method. However, the barrel polishing method generally has a problem that the polishing rate is slower than that of the buff polishing method. Therefore, even when performing medium cutting or heavy cutting such as deburring or smooth finishing of an aluminum alloy work piece, there is a limit to the cutting force. It takes a very long time to smooth the large unevenness, and it may be practically impossible.

As a method for solving such a problem, a method using a chemical polishing action together, for example, Japanese Patent Publication No. 4-547.
The invention described in Japanese Patent Laid-Open No. 61-34188 is proposed. This "barrel polishing method with chemical polishing"
According to the method, the aluminum alloy work piece is barrel-polished using a chemical polishing material in which a hydrochloric acid-hydrogen peroxide system is used in combination with sulfuric acid or an organic acid in a specific ratio, and chemical polishing and mechanical polishing can be performed simultaneously. It is said that there is an effect such that it can be polished with high accuracy and high efficiency, and even polishing of the recessed portion is possible. However, in this method,
Since a chemical polishing agent having a strong acidity is used, it has been feared that droplets of the chemical polishing agent adhere to the barrel polishing apparatus itself used and the surrounding mechanical devices to cause corrosion.

Further, when heavy cutting is usually performed by barrel polishing, there arises a problem that the surface roughness of the workpiece increases as the polishing amount increases. For example, if a chemical polishing material is carelessly used, the amount removed by dissolution can be increased, but the surface roughness becomes extremely large, and sometimes the shape is deformed, which causes many problems. Furthermore, when heavy-cutting a relatively soft metal work piece such as an aluminum alloy using a high hardness ceramic media suitable for heavy cutting, the surface roughness becomes particularly large and Fine powder of wear of the media is stuck and embedded in the surface of the, and a blackish color adheres.
In the gloss finish or painting process, it may become an obstacle such as deterioration of gloss and uneven color. In case of heavy cutting,
Although the polishing time can be shortened and the productivity per hour is improved, the grinding ratio (polishing amount / wear rate) of the media is small, so that the running cost per hour also increases.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and aims to solve the corrosion problem that occurs when an acidic chemical polishing material is used and to improve the surface roughness. (EN) Provided is a wet barrel polishing method in which polishing efficiency is significantly improved while maintaining the same level as conventional methods.
In addition, there is also provided a barrel polishing method capable of reducing the adverse effects of fine particles of wear on the media even in heavy cutting and making the grinding ratio of the media relatively large.

[0007]

The above-mentioned problems are caused by at least 0.5% by weight to 2% by weight of an alkali metal hydroxide.
It can be solved by a barrel polishing method, which is characterized in that the compound and the medium containing are loaded into a barrel polishing tank and a workpiece made of aluminum or aluminum alloy is polished. Further, in the barrel polishing method, the barrel polishing method in which the hydroxide of the alkali metal is caustic soda, and the barrel polishing method in which the compound contains at most 5% by weight of the organic acid salt are more preferable,
Furthermore, the organic acid salts are gluconic acid, citric acid, and tartaric acid.
The barrel polishing method, which is an organic acid salt composed of one kind or two or more kinds of organic acids and an alkali metal, is preferable.

[0008]

In view of the above technical problems, the inventors of the present invention intend to improve the polishing rate particularly in barrel polishing in which a workpiece made of aluminum or an aluminum alloy is subjected to medium cutting or heavy cutting. As a result of advancing the research of, it is possible to use a compound containing an alkali metal hydroxide such as caustic soda alone, or a compound containing the hydroxide and an organic acid salt such as sodium gluconate in combination. The inventors have completed the present invention by finding that it is remarkably effective in improving the polishing rate without deteriorating the surface accuracy of the object.

The present invention is used for a compound containing at least an alkali metal hydroxide to combine a mechanical polishing action by a medium and a chemical polishing action by the hydroxide to produce a workpiece made of aluminum or aluminum alloy. This is a barrel polishing method for polishing an object, characterized in that the compound contains 0.5 wt% to 2 wt% of an alkali metal hydroxide. Further, in the above barrel polishing method, it is possible to more suitably embody it by adopting caustic soda as the alkali metal hydroxide. Here, the content of the hydroxide of the alkali metal is set within the above range because the polishing efficiency is insufficiently improved when the content is less than 0.5% by weight, and the content is more than 2% by weight when the content is more than 2% by weight. This is because the polishing efficiency increases, but the surface roughness becomes abnormally rough.

Further, in the present invention, the mechanical polishing action by the medium and the chemical polishing action by the chemical polishing material in the ordinary barrel polishing exert a synergistic effect, and the compound is an organic acid salt. At most 5
It can be preferably embodied by containing it in an amount of 1% by weight. Furthermore, as an organic acid salt, gluconic acid, citric acid, tartaric acid
Organic acid salt consisting of one or more organic acids and an alkali metal, for example, sodium gluconate, sodium citrate,
It can be embodied with potassium tartrate.

Here, the increase of the content of the organic acid salt improves the polishing efficiency, but the maximum effect is obtained at about 1% by weight,
Since the polishing efficiency tends to decrease gradually even if the amount is further increased, the maximum amount may be 5% by weight, preferably 3% by weight, and more preferably 2% by weight. Further, the minimum content thereof is 0.1% by weight at which a remarkable effect is recognized.

In addition to the above-mentioned materials, a surface active agent, a viscosity modifier, etc. can be appropriately used in the compound. Further, normally, the polishing process is carried out while keeping the inside of the polishing tank at room temperature, but when the temperature rises, the chemical polishing action is more promoted than the mechanical polishing action, so that the temperature can be adjusted as necessary. It is good to take measures. Further, the barrel polishing machine used in the present invention is not limited to a particular type, and a rotary type, a vibration type, a flow type, a swing type, or the like can be appropriately applied.

(Operation) According to the polishing method of the present invention, first, a predetermined amount of an alkali metal hydroxide is used. Therefore, as in the case of using an acidic chemical polishing material, the polishing apparatus and peripheral mechanical devices are used. Will not corrode. Further, since a predetermined amount of organic acid salt is used, the synergistic effect of the chemical polishing action and the mechanical polishing action can dramatically improve the polishing efficiency without deteriorating the surface roughness of the workpiece. it can. Further, even if heavy cutting is performed, there is little adverse effect such as the wear fine powder of the medium being embedded, and the medium is less likely to be consumed, so that there is a remarkable effect that the grinding ratio can be maintained relatively large.

[0014]

Next, the present invention will be described in detail with reference to examples. (Example 1) In this example, the effect of a compound containing an alkali metal hydroxide alone on the polishing results of barrel polishing was examined, and the results are shown in Table 1. Table 2 shows the effect of the combination of organic acid salts. From the results shown in Table 1, it can be understood that it is appropriate that the compound contains 0.5% by weight to 2% by weight of an alkali metal hydroxide. According to the example of caustic soda, in the case of less than 0.5% by weight, the improvement of the polishing efficiency is insufficient as compared with the comparative example containing no alkali metal hydroxide, and in the case of more than 2% by weight. This is because, for example, as in Comparative Example A, the polishing efficiency increases, but the surface roughness becomes abnormally rough. From the viewpoint of polishing efficiency, the most preferable content is 1.0 to 2.0% by weight.
Range. As the alkali metal hydroxide, caustic soda, caustic potash, sodium silicate, etc. can be used. However, in the case of caustic soda (Example No. 5), Rmax is the same as that in the other cases (Example Nos. 6 and 7) and polishing is performed. The amount is large and can be embodied most preferably.

Next, according to the results shown in Table 2, it is preferable that the compound contains 5% by weight or less of the organic acid salt in order to improve the polishing efficiency. Furthermore, as an organic acid salt, an organic acid salt composed of one or more organic acids of gluconic acid, citric acid, tartaric acid and an alkali metal, for example, sodium gluconate, sodium citrate, potassium tartrate is appropriately selected. It turns out that it can be used. Here, the increase of the content of the organic acid salt has a great effect of improving the polishing efficiency while maintaining the surface roughness, but as shown in Example No. 10, the maximum effect is obtained at about 1% by weight. Even if the amount is increased above (Examples Nos. 11 to 13), the polishing efficiency tends to gradually decrease, so that the maximum is 5% by weight, preferably 3% by weight, more preferably 2% by weight.
May be. Further, the minimum content thereof is 0.1% by weight, which produces a remarkable effect as in Example No. 9.

The barrel polishing conditions in each example are as follows unless otherwise specified. Model: Vibration type VF-1016 (manufactured by Shinto Brader), Vibration frequency: 1800 rpm, Amplitude: 4.0 mm, Barrel capacity: 13 l, Media loading amount: 8 l, Compound loading amount: 0.3 l, Workpiece: Aluminum alloy Cast small cylinder (20φ × 15H), polishing time: 60 minutes. The media here is P made of plastic.
1-F20 (for heavy cutting) was used.

[0017]

Table 1 Test results of Example 1 (No. 1)

[0018]

Table 2 Test results of Example 1 (No. 2) Note: The symbols in the organic acid salt column indicate the following metal salts. A: sodium gluconate, B: sodium citrate, C: potassium tartrate.

(Embodiment 2) In this embodiment, a polishing method using the compound according to the present invention is a polishing amount per unit time of a workpiece (unit: mg / hour) and a media consumption rate (unit: mg / hour). ), Grinding ratio (indicated by polishing amount / wear rate), and surface roughness (maximum roughness Rmax unit: μm) of the work piece are compared with those of a normal compound. The results are shown in Table 3. According to this result, in Example N in the polishing amount that represents the polishing force.
In the case of o10, although the good results reaching 4 to 5 times that of the comparative example are shown, it is shown that neither the wear rate nor the surface roughness is relatively increased. It was also found that even in the case of heavy cutting, the wear rate did not increase, and as a result, the grinding ratio increased and the running cost decreased. Here, a plastic medium is used, and the compound of the comparative example contains 1% of a commercially available surfactant and 0.5% of a rust preventive and the like.

[0020]

[Table 3] Test results of Example 2

(Example 3) Table 4 shows the results of the same comparison as in Example 2 except that the medium was changed from a plastic type to a ceramic type. Also in this example, almost the same results as in Example 2 were obtained such that the polishing amount was about twice or more, the wear rate and the surface roughness were almost the same, and the grinding ratio reached about twice. Further, in Comparative Examples No. I and J, darkening that is thought to be due to the media consumption fine powder being embedded in the polished surface occurred, but in Example No. 31,
No such condition was seen in 32.

[0022]

Table 4 Test results of Example 3

(Embodiment 4) This embodiment is the same as the embodiment 2 or 3, except that the type of compound is the type of the present invention (caustic soda: 1.0%, sodium gluconate:
1.0%, surfactant: 0.2%, acidic type (hydrochloric acid: 1.0%, hydrogen peroxide: 1.0) described in the section of the prior art.
%, Sulfuric acid: 1.0%), and the above-mentioned normal type, and the polishing characteristics are compared. Also in this example, it can be seen that the polishing material of the present invention has excellent polishing power as compared with the acidic type compound.

[0024]

Table 5 Test results of Example 4

[0025]

Since the barrel polishing method of the present invention is constructed as described above, the surface roughness of the workpiece made of aluminum or aluminum alloy is maintained at the same level as that of the usual method. However, the polishing efficiency can be significantly improved. Therefore, the polishing processing time can be shortened, the abrasion of the polishing media is small, the dimensional accuracy of the workpiece can be maintained high, and the recessed and depressed portions can be sufficiently polished. Since it is possible to solve the corrosion problem that occurs when there is a problem, there is an effect that the repair cost of mechanical equipment can be reduced in the long term. Further, even in heavy cutting, there is little adverse effect of fine particles of wear on the media, and since the grinding ratio of the media can be made relatively large, there is an excellent effect that the running cost can be reduced. Therefore, the present invention has a very great industrial value as a barrel polishing method that solves the conventional problems.

Claims (4)

[Claims] 1. A barrel polishing tank is charged with a compound containing at least 0.5 wt% to 2 wt% of an alkali metal hydroxide, and a workpiece made of aluminum or an aluminum alloy is polished. Characteristic barrel polishing method. 2. The barrel polishing method according to claim 1, wherein the alkali metal hydroxide is caustic soda. 3. The barrel polishing method according to claim 1, wherein the compound contains at most 5% by weight of an organic acid salt. 4. The alkali metal hydroxide is caustic soda, and the organic acid salt is an organic acid salt composed of one or more kinds of gluconic acid, citric acid, tartaric acid and an alkali metal. Item 4. The barrel polishing method according to Item 3.