JPWO2015156033A1 - Dry barrel polishing method and media manufacturing method - Google Patents

Abstract

In the first step, the surface of the polishing medium (40) is coated with a lubricity-imparting material (44), thereby forming a non-wetting coating portion (44C) to provide lubricity to the surface of the medium (40). Give. In the second step, the media (40) and the workpiece (W) are mixed in the barrel tank (12). In the third step, the workpiece (W) is polished by flowing the media (40) and the workpiece (W) in the barrel tank (12).

Description

  One aspect and embodiments of the present invention relate to a dry barrel polishing method and a method of manufacturing a medium applied to the method.

  A barrel polishing method is known in which a workpiece and a medium are charged into a polishing tank of a barrel polishing apparatus and mixed and fluidized to polish the surface of the workpiece with the medium (for example, Patent Document 1). reference). Such barrel polishing methods include a wet barrel polishing method in which water is put into a polishing tank and a dry barrel polishing method in which water is not put in the polishing tank. Here, although the wet barrel polishing method is widely used for the purpose of gloss finishing of a workpiece or smooth finishing of a workpiece, there is a problem that waste water treatment is required after polishing. For this reason, a dry barrel polishing method may be employed.

Japanese Patent Publication No. 44-23873

  However, in the dry barrel polishing method, it is difficult to ensure finishing performance equivalent to or close to that of the wet barrel polishing method.

  One aspect of the present invention is a dry barrel polishing method capable of ensuring finishing performance equivalent to or close to a wet barrel polishing method in adjusting surface roughness or shape, and a method for producing a medium applied to the method Is the purpose.

  A dry barrel polishing method according to one aspect of the present invention is a dry barrel polishing method in which a workpiece is dry-barrel-polished, and a non-lubricating material is coated on the surface of a medium used in barrel-polishing. A first step of forming a wet coating portion to impart lubricity to the surface of the media; a second step of mixing the media and the workpiece in a polishing tank; and the media and the workpiece. And a third step of polishing the workpiece by causing the material to flow in the polishing tank.

  According to the above configuration, since the fluidity (sliding performance) of the media is improved by the lubricity-imparting material, it is possible to prevent the media from polishing the surface of the work piece more than necessary, and the surface of the work piece. Is processed into a smooth polished surface. The term “non-wetting” as used herein refers to a state in which the surface of the media is not wetted by oil or the like. Note that one aspect of the present invention includes both the case where the first step, the second step and the third step are individually performed, and the case where at least two steps are simultaneously performed.

  In one embodiment, the medium and the workpiece may be caused to flow while supplying the lubricity-imparting material into the polishing tank in the third step.

  According to the above configuration, even if the lubricity-imparting material is gradually scraped off from the medium due to the collision with the workpiece, the surface of the media is coated with the newly-provided lubricity-imparting material. Therefore, the effect of suppressing the surface of the workpiece from becoming unnecessarily rough is maintained. It should be noted that the workpiece is also coated with the lubricity-imparting material. However, the surface of the work piece is gradually polished by polishing the surface of the work piece before or after being coated with media.

  In one embodiment, the lubricity-imparting material may include a fatty acid or a salt thereof.

  According to the said structure, since the lubricity provision material contains the fatty acid or its salt, it can be made low-cost and lubricity can be provided to the surface of a medium. In particular, when the fatty acid or its salt contains sodium fatty acid, good lubricity can be imparted at low cost. Further, when fatty acid sodium is used as the main component of the lubricity-imparting material, the oil and fat hardly adhere to the workpiece, so that the cleaning process can be made unnecessary or simplified.

  In one embodiment, the medium may be an inorganic medium, and may include a holding unit that holds the lubricity-imparting material on the surface.

  Inorganic media (fired media, sintered media) are less expensive than organic media (resin media). However, since inorganic media have lower lubricity than organic media, the impact force on the workpiece is strong. As a result, it is not possible to obtain the same polishing accuracy as in the case of wet barrel polishing. Here, according to the above configuration, since the medium includes the holding portion that holds the lubricity-imparting material on the surface, the adhesion force of the lubricity-imparting material to the medium becomes strong. For this reason, compared with the case where there is no holding | maintenance part, the effect which suppresses that the surface of a to-be-processed surface becomes rough more than necessary can be maintained for a long time.

  In one embodiment, the holding part may be formed by forming the medium into a porous body.

  When the medium is made porous as in the above-described configuration, the specific gravity of the medium is reduced, so that the impact force of the medium on the workpiece is reduced. As a result, the surface of the workpiece can be prevented from becoming unnecessarily rough. Therefore, the finishing performance equivalent to or close to that of the wet barrel polishing method can be ensured by the synergistic effect of the effect of the lubricity imparting material and the effect of the porosity. Note that the form of bubbles in the porous medium described above may be either a closed cell structure or an open cell structure.

In one embodiment, the media is 60 to 80 mass% of aluminum oxide _(Al 2 _{O 3),} and 10 to 30 mass% of silicon dioxide (SiO _2), 4 to 8 wt% of zirconium oxide (ZrO ₂ ), 1 to 3% by mass of calcium oxide (CaO), and 1 to 4% by mass of magnesium oxide (MgO).

  The strength of the porous media is lower than that of media that are not porous, such as cracks generated from the pores during barrel polishing. In the said structure, 1-4 mass% magnesium oxide is contained, and the fall of the intensity | strength as the whole medium more than necessary can be prevented. Further, since the media having this configuration is a sintered media, it has a longer life than the fired media.

  A method for producing a medium used in a dry barrel polishing method according to another aspect of the present invention is a method for producing the medium, and a kneading step of kneading abrasive grains, a binder, magnesium oxide, and a disappearing material powder. A molding step of molding the kneaded material kneaded in the kneading step into a predetermined shape, and sintering the molded body molded in the molding step to form a sintered body, while eliminating the disappearing material powder And a sintering step of forming the holding portion on the surface of the sintered body. Moreover, the addition amount of the said disappearance material powder is the quantity of 1-40 mass% when the sum total of the said abrasive grain, the said binder, the said magnesium oxide, and the said disappearance material powder is 100 mass%.

  By making the entire medium porous with the above configuration, a sintered medium having a holding portion formed on the surface by pores can be obtained. In the kneading step, water may be added as necessary.

  In one embodiment, the vanishing material powder may be aluminum hydroxide powder.

  According to the above configuration, the aluminum hydroxide is dehydrated and decomposed in the sintering process. As a result, the aluminum hydroxide is changed to aluminum oxide and its volume is reduced as a solid content, and the hydroxyl group is emitted as water vapor. Since the aluminum hydroxide powder is dispersed in the molded body, a porous body is formed in the above-described sintering step.

In one embodiment, in the kneading step, at least one of manganese oxide (MnO) and iron oxide (Fe ₂ O ₃ ) is added to a mixed material composed of the abrasive grains, the binder, the magnesium oxide, and the disappearing material powder. And at least one of the mixed materials (that is, one when either manganese oxide or iron oxide is added, or both when both manganese oxide and iron oxide are added) , When the total of 100 mass%, at least one of them (ie, when either manganese oxide or iron oxide is added, while when both manganese oxide and iron oxide are added, both ) Content may be 5% by mass or less.

  According to the above configuration, in the sintering step, the added at least one effectively functions as a sintering aid.

  As described above, according to various aspects of the present invention, there is an excellent effect that a finishing performance equivalent to or close to the wet barrel polishing method can be secured.

It is a schematic block diagram which shows the dry barrel polishing apparatus applied to the dry barrel polishing method which concerns on one Embodiment. It is sectional drawing which expands and schematically shows the surface side of a medium. It is an analysis result which shows that the lubricity imparting material is coated on the surface of the media. 3A shows the result of spectrum analysis, and FIG. 3B shows the result of surface analysis.

  A dry barrel polishing method and a media manufacturing method according to this embodiment will be described. FIG. 1 schematically shows a dry barrel polishing apparatus 10 applied to the dry barrel polishing method according to this embodiment. First, the dry barrel polishing apparatus 10 will be outlined.

(Configuration of dry barrel polishing equipment)
The dry barrel polishing apparatus 10 (hereinafter simply referred to as “barrel polishing apparatus 10”) includes a barrel tank 12 as a polishing tank. The barrel tank 12 has a container shape and is fixed to a pedestal (not shown). A lining 14 is fixed to the inner surface of the barrel tank 12. The barrel tank 12 is charged with a polishing medium 40, a workpiece W, and the like (generally called “mass”). In the drawing, the medium 40 and the workpiece W are schematically shown.

  One end of a dust collecting hose 20 is connected to the bottom of the barrel tank 12. The other end of the dust collection hose 20 is connected to the suction part side of the dust collector 16. The dust collector 16 includes a fan (not shown) that sucks air in the dust collection hose 20 and a filter (not shown) for preventing the dust from being discharged.

  A dust collection hood 18 is disposed on the upper side of the barrel tank 12 as necessary. One end of a dust collection hose 20 </ b> A is connected to the dust collection hood 18. The other end of the dust collection hose 20 </ b> A is connected to the other end side of the dust collection hose 20.

  On the other hand, a turntable 22 is arranged on the bottom upper surface side of the barrel tank 12. The central portion of the rotary disk 22 is fixed to the rotary shaft 24 with the shaft mounting portion. A bearing portion 26 is provided at the bottom of the barrel tank 12. A rotating shaft 24 fixed to the rotating disk 22 is rotatably supported by a bearing portion 26 of the barrel tank 12. The lower end of the rotating shaft 24 is connected to the driving force transmission mechanism 28 on the bottom lower side of the barrel tank 12.

  The driving force transmission mechanism 28 includes a pair of pulleys 30 and 32 and a V belt 34 wound around the pair of pulleys 30 and 32. The rotary shaft 24 described above is fixed coaxially to the axial center of one pulley 30. The output shaft of the motor 36 with a speed reducer is fixed coaxially to the axial center of the other pulley 32.

  As described above, the barrel polishing apparatus 10 causes the mass to flow in the barrel tank 12 by rotating the turntable 22 by driving the motor 36. Such a barrel polishing method is called a fluid barrel.

(media)
Next, the outline of the medium 40 charged in the barrel tank 12 will be described. Depending on the purpose of polishing, the medium 40 is a small particle formed in an arbitrary shape such as a spherical shape, a triangular pyramid shape, a triangular prism shape, a cylindrical shape, a circularly cut shape of a circular cylinder, or a quadrangular prism shape. Is the body. As an example, the medium 40 of the present embodiment has a triangular prism shape with a height of 6 mm. The medium 40 flows together with the workpiece W in the barrel tank 12 and polishes the workpiece W by the frictional force generated between the media 40 and the workpiece W.

  FIG. 2 shows a schematic cross-sectional view in which the surface side of the medium 40 is enlarged. A polishing medium 40 shown in FIG. 2 is an inorganic medium. As an inorganic medium, for example, a sintered body medium (baked medium) obtained by firing a mixture of abrasive grains and a clay material, and a sintered body medium formed by sintering abrasive grains (fired media) Sintered media). In general, inorganic media is less expensive than organic media (resin media formed by mixing a resin and an abrasive). However, since the surface of the inorganic medium is hard and the impact force against the workpiece W is too strong, it is generally difficult to achieve polishing equivalent to wet barrel polishing. On the other hand, when the medium 40 is a porous body (the whole is porous), the specific gravity of the medium 40 is reduced by the pores, and thus the collision energy of the medium 40 against the workpiece W is reduced. As a result, since the impact force of the medium 40 on the workpiece W is reduced, it is possible to suppress the surface of the workpiece W from becoming unnecessarily rough. Furthermore, a buffering effect by pores formed in the vicinity of the surface of the medium 40 can be expected. In addition, among inorganic media, sintered media have a lower wear rate and longer life compared to sintered media. In this embodiment, a sintered medium is selected.

  In addition, a concave holding portion 42 is formed on the surface of the medium 40 to hold and hold a lubricity imparting material 44 described later. The holding portion 42 holds the lubricity imparting material 44 firmly to the medium 40. That is, the adhesion of the lubricity imparting material 44 to the medium 40 is increased. The holding portion 42 may be formed by providing a groove, may be formed by providing dimples, or may be formed by providing irregularities. The holding part 42 is formed of irregularities formed on the surface of the medium 40 by the pores of the medium 40 that is a porous body. Thus, by making the medium 40 a porous body, it is possible to obtain both the effects of suppressing the impact force described above and the effect of firmly holding the lubricity-imparting material 44. Therefore, it is possible to prevent the surface of the workpiece W from being roughed more than necessary.

  The lubricity imparting material 44 contains almost no oil or fat. For example, the oil and fat content of the lubricity imparting material 44 may be 0.5 mass% or less. Since the lubricity imparting material 44 is substantially free of oils and fats, when the lubricity imparting material 44 is coated on the surface of the media 40, the surface of the media 40 is lubricated without being wetted. Can be granted. As an example, the lubricity imparting material 44 in the present embodiment is composed of fatty acid sodium and some inevitable impurities. Examples of the fatty acid in the fatty acid sodium include tangle acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, valmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and ricinolenic acid. The fatty acid may be a single type of fatty acid or a mixture containing two or more types of fatty acids.

  Further, the lubricity imparting material 44 may contain a fatty acid instead of or together with the fatty acid sodium. Examples of the fatty acid include lauric acid and oleic acid. Further, the lubricity-imparting material 44 may contain other fatty acid metal salts such as fatty acid magnesium, fatty acid calcium, or fatty acid potassium, for example, instead of or together with fatty acid sodium.

The medium 40 includes at least 60 to 80% by mass of aluminum oxide, 10 to 30% by mass of silicon dioxide, 4 to 8% by mass of zirconium oxide, and 1 to 3% by mass of calcium oxide. Some inevitable impurities (for example, K ₂ O, TiO ₂ , Na ₂ O, HfO _2, P ₂ O _3, etc.) may be included. Inevitable impurities may be 3% or less (or 2% or less).

  However, the strength of the entire medium 40 is reduced by making the entire medium 40 porous. For example, the media 40 may be cracked or chipped from the pores due to impact caused by barrel polishing. Therefore, by further including magnesium oxide as a reinforcing material, even if the medium 40 is made porous, the strength of the medium 40 can be improved to the extent that the medium 40 is not cracked or chipped during barrel polishing. The content of magnesium oxide may be 1 to 4% by mass (or 2 to 3% by mass). In this case, it has been confirmed by experiments that the above-described effects can be obtained.

(Media production method)
Here, a method for manufacturing the medium 40 (a method for manufacturing the medium 40) will be described.

  In the method for manufacturing the media 40, first, a kneading step is performed. In this kneading step, abrasive grains, a binder, magnesium oxide as a reinforcing material, and aluminum hydroxide powder as a disappearing material powder are weighed so as to have a predetermined content and then kneaded (collectively, these materials Hereinafter referred to as “mixed material a”). During kneading, water may be added as necessary. The addition amount of the aluminum hydroxide powder is 1 to 40% by mass when the mixed material a is 100% by mass.

  As the abrasive grains, alumina-based abrasive grains (alundum), silicon carbide-based abrasive grains (carborundum), zirconia alumina abrasive grains, diamond abrasive grains, or CBN abrasive grains can be used. When white alumina-based abrasive grains (WA) are used as the abrasive grains, high polishing power can be obtained at a low price, and the color of the abrasive grains is not transferred to the workpiece, which is preferable. The average particle diameter of the abrasive grains is appropriately selected according to the purpose of polishing. For example, when the purpose is fine polishing, it is selected from the range of 1 to 40 μm. Here, when the particle diameter of the abrasive grains is too small, the polishing power of the media is lowered. On the other hand, when the particle diameter of the abrasive grains is too large, the bonding force between the particles is weak and the strength of the media is lowered.

  The binder is a binding material for bonding abrasive grains when sintering. The binder is appropriately selected depending on the type of abrasive grains or the sintering temperature. In the present embodiment, the binder includes at least silicon dioxide, zirconium oxide, and calcium oxide. In addition, when magnesium oxide is contained in a binder, the said magnesium oxide can be utilized as a reinforcing material.

  In the kneading step of the present embodiment, as an example, a sintering aid is added to the mixed material a. The sintering aid can be at least one of manganese oxide and iron oxide (that is, either one or both). The addition amount of the sintering aid is 5% by mass or less when the total of the mixed material a and the sintering aid is 100% by mass (when a plurality of materials are used as the sintering aid, The total is 5 mass% or less).

  In the next molding step, the kneaded material kneaded in the kneading step is put into an extrusion molding machine and molded into a predetermined shape (triangular prism shape in the present embodiment).

  In the next sintering step, the molded body molded in the molding step is placed in a dry state in a heat-resistant container and sintered in a furnace at a predetermined temperature for a predetermined time. In this sintering process, the aluminum hydroxide is dehydrated and decomposed. As a result, the volume is changed to aluminum oxide and the volume is reduced as a solid content, and the hydroxyl group is emitted as water vapor. That is, in this step, aluminum hydroxide is lost. By the kneading described above, the aluminum hydroxide is uniformly dispersed in the mixed material a. Accordingly, a porous medium having a closed cell structure is formed by this sintering step, and a sintered medium 40 having a holding portion 42 formed on the surface is obtained.

  If the content ratio of the aluminum hydroxide powder is too high, the life is shortened. Therefore, the content ratio of the aluminum hydroxide powder may be as described above. In this sintering step, at least one of manganese oxide and iron oxide added in the kneading step effectively functions as a sintering aid.

(Dry barrel polishing method)
Next, a dry barrel polishing method using the medium 40 will be described.

  First, the medium 40 and the lubricity imparting material (not shown in FIG. 1) are charged into the barrel tank 12 of the barrel polishing apparatus 10 shown in FIG. Next, the dust collector 16 connected to the barrel polishing apparatus 10 is operated.

  Next, the barrel polishing apparatus 10 is operated, and the medium 40 and the lubricity-imparting material (not shown in FIG. 1) are caused to flow in the barrel tank 12. Thereby, as shown in FIG. 2, the surface of the polishing medium 40 is coated with the lubricity imparting material 44 containing almost no oil or fat. Specifically, a non-wetting coating portion 44C is formed on the surface of the medium 40 to impart lubricity to the surface of the medium 40 (first step). As an example, the lubricity imparting material 44 is coated on the surface of the medium 40 by mixing and flowing a powdery material having a particle size of about 5 to 800 μm (but not limited to this size) with the medium 40. . In the present embodiment, for example, the main component of the lubricity imparting material 44 is sodium fatty acid. Therefore, the cost of the lubricity imparting material 44 can be reduced and lubricity can be imparted to the surface of the medium 40.

  Further, the lubricity imparting material 44 is coated on the surface of the medium 40 by mixing and flowing a cube-shaped material (for example, a cube shape of 10 mm × 10 mm × 10 mm to 70 mm × 70 mm × 70 mm) with the medium 40. May be. The lubricity imparting material 44 may be coated on the surface of the medium 40 by, for example, mixing a liquid (for example, a concentration of 10 vol%) with the medium 40 and solidifying it while flowing. When a liquid material is mixed and coated as the lubricity imparting material 44, there is an advantage that the quantitative addition is easy and it is difficult to be sucked into the dust collector 16 (see FIG. 1), and the quantitative addition to the centrifugal barrel is also applicable. is there. In addition, when the liquid lubricity imparting material 44 is charged, an amount that does not wet the surface of the media 40 is charged.

  The operation of the barrel polishing apparatus 10 is stopped after a predetermined time has elapsed since the barrel polishing apparatus 10 shown in FIG. 1 is operated. Next, the workpiece W is charged into the barrel tank 12 of the barrel polishing apparatus 10, and the media 40 and the workpiece W are mixed in the barrel tank 12 (second step).

  Next, the barrel polishing apparatus 10 is operated, and the medium 40 whose surface is coated with the lubricity imparting material 44 (see FIG. 2) and the workpiece W are caused to flow in the barrel tank 12. The workpiece W is polished by bringing the medium 40 into sliding contact with the workpiece W by this flow (third step). At this time, since the fluidity (sliding performance) of the medium 40 is improved by the lubricity imparting material 44, an excessive polishing load due to the collision of the medium 40 is not imparted to the workpiece W. In addition, since the impact force when colliding with the workpiece W is buffered by the pores of the medium 40, excessive polishing force due to the collision of the media 40 is not applied to the workpiece W. For this reason, it is suppressed that the medium 40 roughens the surface of the workpiece W more than necessary, and polishing for reducing the surface roughness of the workpiece W can be performed. That is, the surface of the workpiece W is processed into a smooth polished surface.

  In addition, as shown in FIG. 2, the porous medium 40 includes the holding portion 42 on the entire surface, so that the adhesion of the lubricity-imparting material 44 to the medium 40 is increased. Thereby, since the media 40 can hold the lubricity-imparting material 44 for a long time compared with the case where the holding portion 42 is not provided, the effect of suppressing the surface of the workpiece W from being roughened more than necessary. Can last longer. For this reason, the performance of the lubricity imparting material 44 can be sufficiently exhibited.

  Further, in this step (third step), by operating a supply device (not shown) of the lubricity-imparting material 44, the medium 40 and the workpiece are supplied while supplying the lubricity-imparting material 44 into the barrel tank 12. Let W flow. For this reason, even if the lubricity-imparting material 44 is gradually scraped off from the medium 40 by the collision with the workpiece W, the surface of the medium 40 is coated with the newly-provided lubricity-imparting material 44. Therefore, the effect of suppressing the surface of the workpiece W from being roughed more than necessary is maintained. It should be noted that the work piece W is about to be coated with the lubricity imparting material 44. However, the surface of the workpiece W before or after being coated is polished with the medium 40 so that the surface of the workpiece W is gradually polished.

  After a predetermined time has elapsed since the barrel polishing apparatus 10 was operated, the operation of the supply device for the lubricity imparting material 44 is stopped, then the operation of the barrel polishing apparatus 10 is stopped, and then the operation of the dust collector 16 is stopped. Then, the medium 40 and the workpiece W are discharged from the barrel tank 12 of the barrel polishing apparatus 10, and these are separated to collect the workpiece W.

  As described above, according to the present embodiment, a finishing performance equivalent to or close to that of the wet barrel polishing method can be ensured while being a dry barrel polishing method.

  For example, in a conventional example in which a surface coated with oil or fat is polished as a medium, the oil or fat adheres to the workpiece, and thus a cleaning step is required. On the other hand, in the case of the present embodiment, the surface of the medium 40 is coated with the lubricity imparting material 44 containing almost no oil and fat to form the non-wetting coating portion 44C. For this reason, fats and oils hardly adhere to the workpiece W. As a result, there is an advantage that the cleaning process can be eliminated or simplified.

  Next, examples will be described.

  First, Table 1 shows the test results for confirming the fluidity of the media. Here, the numerical value in the table is the angle of repose of the measured media. After the medium was placed on a plate having a surface roughness Ra = 0.146 μm, the plate was gradually inclined, and the angle of inclination when the medium dropped along the plate was defined as the repose angle. This measurement is performed on media coated with a lubricity-imparting material (indicated as “coated” in the table) and media not coated with a lubricity-indicated material (denoted as “uncoated” in the table). On the other hand, 20 pieces were measured.

  According to the results in Table 1, it can be seen that the angle of repose of the media is reduced by coating. As a result, it was suggested that when the surface of the media is coated with a lubricity-imparting material, the lubricity of the media is improved, so that the fluidity of the media is improved during barrel polishing.

  On the other hand, the case where the surface of the media was coated with sodium fatty acid (lubricity imparting material) was used as an example (Examples 1 to 10), and the case where the surface of the media was not coated was used as a comparative example (Comparative Examples 1 to 5). The test which grind | polishes a workpiece was performed by making it flow in the state mixed with the workpiece in the tank (polishing tank).

  The conditions for polishing (barrel polishing) are as shown in Table 2 below. As a workpiece, one workpiece for measurement (φ45mm x t15mm S45C material (carbon steel for mechanical structure: JIS (Japanese Industrial Standards))) and 12L (apparent volume) dummy workpiece (30 mm × 30 mm × t 3 mm SS400 material (general structural rolled steel: JIS)).

  A supplementary explanation of the media types in Table 2 will be given. Media A and media C (sintered media) are media formed by sintering abrasive grains. Media B and media D (fired media) are media formed by sintering abrasive grains and a clay material. The medium E (resin medium) is a medium formed by mixing a resin and an abrasive.

  Table 3 below shows the conditions of Examples 1 to 9 and Comparative Examples 1 to 5, and the results of measuring the surface roughness, the polishing amount, and the wear rate.

  In the condition items in Table 3, the item “media” indicates which of the media in Table 2, and the item “method” indicates whether the method is a dry barrel polishing method or a wet barrel polishing method. . In the wet barrel polishing method, 11 L of water was put in the polishing tank, and 50 ml of polishing aid (compound) was added.

  The item “input of fatty acid sodium” indicates whether the process of coating the surface of the medium with sodium fatty acid as a lubricity-imparting material is “present” or “absent”. Here, in the case of “Yes”, it indicates in parentheses whether the powder is in a powder, solid, or liquid state.

  The formation of fatty acid sodium on the surface of the media is confirmed by spectral analysis and surface analysis (mapping) using a scanning electron microscope (manufactured by Hitachi Ltd .; S3400) and an energy dispersive X-ray analyzer (manufactured by EDAX; Genesis 4000). ) Confirmed. As an example, FIG. 3A shows the result of spectral analysis of Example 3, and FIG. 3B shows the result of surface analysis of the media surfaces of Example 3 and Comparative Example 1. In the media of Example 3, the presence of sodium fatty acid was confirmed since ions (sodium ions) derived from fatty acid sodium were detected in FIG. In addition, the other peak in the figure shows the component derived from a medium. Furthermore, FIG. 3B shows that fatty acid sodium is distributed over the entire surface of the media. In other words, it was shown that when sodium fatty acid was added during barrel polishing, the entire surface of the media was coated with sodium fatty acid.

In addition, in the condition items of Table 3, the item of “Al (OH) ₃ ” indicates whether or not aluminum hydroxide powder is added in the kneading step when manufacturing the media. When aluminum hydroxide powder is added, the ratio of the added amount is shown in parentheses. The ratio of the amount of aluminum hydroxide added indicated in parentheses is mass% when the mixed material (mixed material a in the embodiment described above) is 100 mass%. When Al (OH) ₃ is added, the medium becomes a porous body. When Al (OH) ₃ is not added, the medium does not become a porous body and the surface has a relatively smooth surface. It becomes.

  Furthermore, the item “number of batches” indicates the number of times of polishing with the same medium. In the actual polishing process, after the first polishing, the workpiece is taken out, after which a new workpiece is inserted and the second polishing is performed with the same media. Thus, the polishing and the removal and charging of the workpiece are repeated. Here, the example in which the number of batches is 1 in the table indicates the measurement result of the workpiece taken out after the first polishing, and the example in which the number of batches is 10 in the table (Example 9) is The measurement result of the workpiece taken out after the 10th polishing is shown.

  Moreover, in the result item of Table 3, "surface roughness" is the surface roughness Ra (JIS B6001; 1994) of the surface of the work piece by using a surface shape roughness measuring instrument (manufactured by Tokyo Seimitsu; Surfcom 1500DX). It is the result of having measured. The unit of “surface roughness” is μm. The “polishing amount” is determined by measuring “mass of workpiece before processing” and “mass of workpiece after processing” with an electronic balance (manufactured by Shimadzu Corporation; IPS-DP10), and the difference between them. It is the result of converting and evaluating per unit time. The unit of “polishing amount” is mg / h.

  In addition, the “wear rate” is obtained by measuring “mass of media before processing (for measurement)” and “mass of media after processing (for measurement)” with the above-described electronic balance. This is the calculated result. The unit of “wear rate” is% / h.

  According to the result of Table 3, in Examples 1-10, it turns out that it is finished with the surface roughness equivalent to or close to the wet barrel polishing method of Comparative Examples 3 and 4. In particular, when Example 3 and Example 10 are compared, it can be seen that better results are obtained when a sintered medium is selected as the medium.

(Supplementary explanation of the embodiment)
As a modification of the above embodiment, the workpiece may be polished by fluidizing the mass by planetary rotation or vibration of the polishing tank. In addition to the fluid barrel as in the above-described embodiment, the types of barrel polishing include, for example, what are called a centrifugal barrel, a vibration barrel, a rotary barrel, a gyro barrel, and the like.

  As a modification of the above embodiment, the polishing media, the workpiece, and the lubricity-imparting material are mixed in the polishing tank (second step), and these masses are allowed to flow in the polishing tank. The surface of the media is coated with a lubricity-imparting material. Thus, a non-wetting coating portion is formed to provide lubricity to the surface of the media (first step), and the workpiece is polished by flowing the media and the workpiece in a polishing tank ( (Third step) may be adopted.

  In the above embodiment, in the third step, the medium 40 and the workpiece W are caused to flow while supplying the lubricity-imparting material into the barrel tank 12 by a supply device (not shown). However, instead of supplying such a lubricity-imparting material, the lubricity-imparting material may be preliminarily charged into the barrel tank 12 by an amount required additionally.

  As a modification of the above embodiment, depending on the performance (finishing performance, life, etc.) required for the media, the composition of the media of the sintered body is, for example, 60 to 80% by mass of aluminum oxide and 10 to 30% by mass. % Of silicon dioxide, 4 to 8% by mass of zirconium oxide, 1 to 3% by mass of calcium oxide, and less than 1% by mass or 5% by mass of magnesium oxide. Is possible.

Further, as a modification of the method for manufacturing the media of the above embodiment, the disappearing material powder may be other disappearing material powder such as a foamed polystyrene resin powder or a graphite powder. In addition, when a polystyrene resin is used as the disappearance material in the ceramic binder, impurities (for example, carbon) due to the disappearance material may remain in the grain boundaries in the sintered media, and this impurity is the strength of the media. There is a possibility that it will contribute to the decrease (crack generation). On the other hand, when aluminum hydroxide is used as the disappearing material as in the above-described embodiment, even if sintering is performed, the aluminum hydroxide is water vapor and aluminum oxide (the main component of the ceramic binder ( And Al ₂ O ₃ ). Therefore, there is an advantage that impurities due to the lost material do not remain in the sintered media.

  Further, as a modification of the method for manufacturing the media of the above embodiment, a method in which manganese oxide and iron oxide are not added in the kneading step can be adopted.

  In addition, the said embodiment and the above-mentioned some modification can be implemented combining suitably.

  Although the embodiment and the modified examples have been described above, the present invention is not limited to the above, and it is needless to say that various modifications can be made without departing from the gist of the present invention. is there.

DESCRIPTION OF SYMBOLS 12 ... Barrel tank (polishing tank), 40 ... Media, 42 ... Holding part, 44 ... Lubricity imparting material, 44C ... Coating part, W ... Workpiece.

Claims (11)

A dry barrel polishing method for barrel-polishing a workpiece in a dry manner,
Coating the surface of the media used in the barrel polishing with a lubricity-imparting material to form a non-wetting coating portion to impart lubricity to the surface of the media;
A second step of mixing the media and the workpiece in a polishing tank;
A third step of polishing the workpiece by flowing the media and the workpiece in the polishing tank,
Dry barrel polishing method. In the third step, the medium and the workpiece are caused to flow while supplying the lubricity-imparting material into the polishing tank.
The dry barrel polishing method according to claim 1. The lubricity-imparting material includes a fatty acid or a salt thereof.
The dry barrel polishing method according to claim 1 or 2. The fatty acid or salt thereof includes fatty acid sodium,
The dry barrel polishing method according to claim 3. The medium is an inorganic medium, and the surface of the medium is provided with a holding unit that holds the lubricity-imparting material in,
The dry barrel grinding | polishing method of any one of Claims 1-4. The holding part is formed by the medium being a porous body,
The dry barrel polishing method according to claim 5. The media comprises 60-80 wt% aluminum oxide, 10-30 wt% silicon dioxide, 4-8 wt% zirconium oxide, 1-3 wt% calcium oxide, and 1-4 wt% A sintered body containing at least magnesium oxide,
The dry barrel polishing method according to claim 6. A method for producing a medium for use in the dry barrel polishing method according to claim 7,
A kneading step of kneading the abrasive grains, the binder, magnesium oxide and the disappearing material powder;
A molding step of molding the kneaded material kneaded in the kneading step into a predetermined shape;
Sintering the formed body formed in the forming step to form a sintered body, and forming the holding part on the surface of the sintered body by eliminating the disappearing material powder,
Media manufacturing method. The addition amount of the disappearing material powder is an amount of 1 to 40% by mass when the total of the abrasive grains, the binder, the magnesium oxide and the disappearing material powder is 100% by mass.
The method for manufacturing a medium according to claim 8. The disappearing material powder is a powder of aluminum hydroxide,
The method for producing a medium according to claim 8 or 9. In the kneading step, at least one of manganese oxide and iron oxide is added to a mixed material containing the abrasive grains, the binder, the magnesium oxide, and the disappearing material powder, and the mixed material, the manganese oxide, and the iron oxide are mixed. When the total of at least one and 100 mass%, the content of at least one of the manganese oxide and the iron oxide is 5 mass% or less,
The method for manufacturing a medium according to any one of claims 8 to 10.