JP2016000450A - Barrel polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dry-type barrel polishing method that does not need to apply an agent of corrosion inhibitor to workpiece after barrel polishing.SOLUTION: The workpiece and a mass containing a polishing medium are loaded in a barrel tank for barrel polishing. The polishing medium has a composition containing a resin so as to polish the workpiece and form an extremely thin resin film on the workpiece at the same time by causing a resin component contained in the polishing medium to adhere to a surface of the workpiece. Thus, this polishing method can impart very high-antirust function to the workpiece without affecting dimensional accuracy of the workpiece.

Description

  The present invention relates to a dry barrel polishing method capable of imparting a rust prevention function to a workpiece without coating the surface of the workpiece with a chemical rust inhibitor.

  Barrel polishing is widely used for surface treatment of workpieces (deburring, rounding, surface roughness adjustment, smooth finish, gloss finish, mirror finish, thin film layer removal, etc.). In barrel polishing, the work piece is polished by fluidizing the mass charged in the barrel tank. Here, the mass refers to a material composed of articles (workpieces and polishing media, etc. in dry type) charged in a barrel tank. The barrel polishing device is a fluid barrel device that fluidizes the mass by rotating a rotating plate provided at the bottom of the barrel vessel, a centrifugal barrel device that fluidizes the mass by revolving the barrel vessel, and a barrel vessel A vibration barrel device that fluidizes a mass by vibrating the plate is widely known.

  When polishing a metal workpiece, there is a problem that rust is generated on the surface of the workpiece as time passes after polishing. Therefore, in dry barrel polishing, a process of coating a rust preventive agent on a polished workpiece is performed. In wet barrel polishing, a compound containing a rust inhibitor is added and polished to coat the workpiece with the rust inhibitor. Patent Document 1 describes a barrel polishing system that prevents a workpiece polished by rotation of a barrel tank from being rusted in the workpiece by immersing the workpiece in a rust prevention liquid.

  The surface of the workpiece processed by the system described in Patent Document 1 is coated with a rust inhibitor. In general, as an antirust agent, for example, chemicals such as organic acid salts, diethanolamine and triethanolamine are used.

JP 2002-254290 A

  In the case of using the above-mentioned chemicals, it is necessary to provide a process for washing the workpiece and removing the rust preventive agent before assembling to the product in a subsequent process. If this process of removing the rust preventive is added, there are problems such as an increase in the manufacturing cost of the product due to an increase in the man-hours related to the treatment and cleaning of the wastewater generated by the cleaning. Therefore, the present invention provides a barrel polishing method capable of performing barrel polishing and performing rust prevention treatment without coating a surface of a workpiece with a chemical rust preventive agent.

  In one aspect of the present invention, a barrel polishing method is provided in which a mass including a workpiece and an abrasive medium is fluidized to polish the workpiece in a dry process. The barrel polishing method includes a mass charging step of charging the mass into a barrel tank, a fluidizing step of fluidizing the mass in the barrel tank, and polishing a workpiece with the polishing media and processing And a polishing / rust prevention step for forming a film on the surface of the object to give a rust prevention function. According to the barrel polishing method applied to one side surface, by fluidizing the mass (fluidization step), the workpiece is polished and a film is formed on the surface of the workpiece (polishing / rust prevention step). . Since this film prevents the surface of the workpiece from being in contact with oxygen and moisture in the air, it is possible to prevent rust from being generated on the surface of the workpiece. In this barrel polishing method, there is no need to use a chemical rust preventive agent as in the prior art, so there is no need to provide a step of removing the rust preventive agent in a subsequent step. In one embodiment, the polishing / rust prevention step may form the film having a thickness of 0.1 nm to 10 nm. By forming an extremely thin film in this way, a rust prevention effect can be obtained without affecting the dimensional accuracy of the workpiece.

  In one embodiment, the polishing / rust prevention step comprises polishing the workpiece with a polishing medium having a structure in which abrasive grains are dispersed in the resin, and applying the resin film on the surface of the workpiece with the resin contained in the polishing medium. You may form and give a rust prevention function. According to this embodiment, the rust prevention function can be imparted to the workpiece only by inserting the polishing media and the workpiece into the barrel tank and polishing them.

  In one form, the said mass may further contain the rust prevention function provision material which is a powder or a molded object. In the polishing / rust prevention step, the workpiece is polished with the polishing media, and a film of a component constituting the rust prevention function-imparting material is formed on the surface of the workpiece by the rust prevention function-imparting material. You may provide a rust prevention function. In this embodiment, since the film for imparting the antirust function to the workpiece can be formed by the antirust function imparting material, the material of the polishing media is not particularly limited. That is, since the polishing media can be freely selected according to the required finishing accuracy, barrel polishing can be performed efficiently. In particular, if the rust preventive function-imparting material is composed mainly of at least one of a resin, a fatty acid or a salt thereof, an extremely thin film can be easily formed on the surface of the work piece. A rust prevention function can be easily provided.

  In the case where the mass further includes a rust preventive function-imparting material that is a powder or a molded body, the barrel polishing method uses the rust preventive function imparting material to form a non-wet film on the surface of the abrasive media. You may further provide the process of providing lubricity to the surface. Since the lubricity of the polishing media is improved by the film formed on the surface of the polishing media, the impact force of the polishing media on the workpiece can be weakened when the mass is fluidized in the barrel tank. That is, according to this barrel polishing method, it is possible to impart a rust prevention function to the workpiece and to adjust the finished degree (surface roughness, shape adjustment, etc.) of the workpiece.

  In one embodiment, the mass further includes abrasive grains, and in the polishing / rust prevention step, the workpiece is polished with the polishing media and the abrasive grains, and the workpiece is coated with the antirust function-imparting material. You may form the film | membrane of the main component of this rust prevention function provision material on the surface. The degree of finish can be adjusted by adjusting the polishing power with the abrasive grains.

  In one embodiment, the resin in the rust preventive function-imparting material containing the abrasive media or resin as a main component may contain nylon as a main component. If it is resin, it can give a rust prevention function to a to-be-processed object, but if nylon is the main component, it can give a particularly high rust prevention function. Moreover, a rust prevention function can be provided at low cost.

  According to one aspect or each embodiment of the present invention, it is possible to simultaneously polish a workpiece and impart a rust prevention function. Moreover, since the surface of the workpiece is not coated with a chemical rust preventive agent as in the prior art, there is no need for a step of removing the rust preventive agent in a subsequent step.

It is a schematic diagram for demonstrating the centrifugal barrel grinding | polishing apparatus used in embodiment of this invention. It is a flowchart which shows an example of the process of a workpiece used by embodiment of this invention. It is a flowchart which shows the barrel grinding | polishing method which concerns on one Embodiment. It is an example (Example 1) of the analysis result of the surface of the workpiece in 1st embodiment. FIG. 4A shows the result of negative ion spectrum analysis, and FIG. 4B shows the result of mapping analysis. It is an example of the analysis result of the surface of the workpiece in 2nd embodiment. 5A shows the spectrum analysis results of positive ions of Example 20 and the unprocessed product, and FIG. 5B shows the results of mapping analysis of Example 20. FIG.

  An example of the present invention will be described with reference to the drawings. In the following description, an example in which SUJ2 material (JIS (Japan Industrial Standards) G4805; defined in 2008), which is an iron-based workpiece, is dry-polished with a centrifugal barrel polishing apparatus will be described as an example. Note that the vertical and horizontal directions in the description refer to the directions in the figure unless otherwise specified.

  FIG. 1 is a schematic diagram of a barrel polishing apparatus 10 according to the present embodiment. A barrel polishing apparatus 10 shown in FIG. 1 is a centrifugal barrel polishing apparatus, and includes four barrel tanks 11 into which masses are inserted, four barrel tank cases 12 to which the barrel tanks 11 are detachably fixed, and barrels. A pair of turrets 13 (revolving disks) that rotatably fix the tank case 12, a revolving shaft 14, a drive mechanism 15 that rotates the turret 13 about the revolving shaft 14, and the rotation of the turret 13 And a driven mechanism 16 that rotates the barrel tank case 12. In FIG. 1, only three barrel tanks 11 and three barrel tank cases 12 are illustrated for convenience.

  The barrel tank 11 is a hollow container that defines a space having an octagonal cross-sectional shape therein, and a cylindrical barrel tank body whose upper surface is open, and the internal space can be sealed by covering the opening. And a barrel tank lid.

  Each barrel tank case 12 is provided with a rotation shaft 12a at both ends. The barrel tank case 12 is configured such that the barrel tank 11 whose inside is sealed can be detachably fixed to the barrel tank case 12.

  The pair of turrets 13 have a disk shape and are provided so as to face each other. The center of each turret 13 (the center of the side surface which is a circular plane) is provided with a first bearing 13a to which the revolving shaft 14 can be rotatably fitted. Each turret 13 is provided with a plurality of second bearings 13b at equal intervals along the circumferential direction thereof. These second bearings 13b are individually fitted to the rotation shafts 12a of the plurality of barrel tank cases 12, and each rotation shaft 12a is rotatably supported. The turret 13 is rotatably fixed to the revolving shaft 14 fixed to the shaft holder 14a via the first bearing 13a. Moreover, the barrel tank case 12 is arrange | positioned so that it may be pinched | interposed into each turret 13 via the autorotation shaft 12a and the 2nd bearing 13b. With this configuration, the barrel tank case 12 is arranged between the pair of turrets 13 at equal intervals and so as to be rotatable relative to the turret 13.

  The drive mechanism 15 includes a drive motor 15a, a motor pulley 15b fixed to the rotation shaft of the drive motor 15a, a revolving pulley 15c provided on the outer periphery of one of the turrets (left side in FIG. 1), and a motor pulley 15b. And a drive belt 15d spanned between the pulley 15c.

  The driven mechanism 16 includes a driving pulley 16a fixed to the rotation shaft, a driven pulley 16b fixed to the rotation shaft 12a, and a driven belt 16c spanned between the driving pulley 16a and the driven pulley 16b. Is done.

  When the drive motor 15a is operated, the turret 13 rotates about the revolution shaft 14. As the turret 13 rotates, the barrel tank 11 fixed to the barrel tank case 12 turns (revolves) around the revolution shaft 14. The barrel tank 11 is rotated (spinned) by the driven mechanism 16 in the direction opposite to the rotation direction of the turret 13 with the rotation shaft 12a as the axis.

  As described above, the barrel tank 11 can rotate by its own rotation and turn by the rotation of the turret 13. When the barrel tank 11 rotates and revolves (planetary motion), the mass including the workpiece and the polishing media is in a fluid state. Thus, the workpiece is polished by contact with the polishing media, contact between the workpieces, and contact with the wall surface of the barrel tank 11.

  As an example of the case where the workpiece is iron-based, FIG. 2 shows a general machining process of a bearing component made of SUJ2 material. In the processing step shown in FIG. 2, after the bulk body is cut into the shape of the bearing part (S01), heat treatment is performed (S02), and this is barrel-polished as a workpiece to give a gloss finish (adjustment of surface roughness) (S03). Next, the workpiece is washed (S04). If the workpiece is left after washing the workpiece, rust is generated on the surface of the workpiece as time passes. In particular, since red rust is highly erodible to the workpiece, there is a problem that the dimensional accuracy of the workpiece deteriorates or the strength decreases with the progress of red rust. Therefore, in the conventional method, a rust prevention treatment is performed so that rust does not occur before assembly into the product (S05). This rust prevention treatment is performed by applying an aqueous solution of a rust inhibitor (chemical) or immersing the workpiece in an aqueous solution of the rust inhibitor and coating the surface of the workpiece with the rust inhibitor. The workpiece is inspected for dimensions and the like before being assembled as a bearing. At this time, if a rust preventive agent is attached, it may cause a failure of the measuring instrument or affect the reliability of the measurement result. For this reason, after wash | cleaning a workpiece and removing the rust preventive agent which adheres (S06), it is assembled | attached as a bearing (S07) and a bearing is completed.

  When cleaning (S05) for removing the rust inhibitor, a large amount of waste water is generated. In order to treat this wastewater, a production method that does not require a step of washing the rust preventive agent is required because of an increase in the production cost of the product and the influence on the environment. As a result of intensive research, we have found a barrel polishing method that can polish a workpiece and provide a rust prevention function. Thereby, it could be set as the manufacturing method which does not require the rust prevention process (S04) by a rust inhibitor, and the process (S05) of removing this rust inhibitor. This barrel polishing method will be described in detail below.

(First embodiment)
Hereinafter, the barrel polishing method according to the first embodiment will be described. FIG. 3 is a flowchart showing a barrel polishing method according to the first embodiment. In this barrel polishing method, first, a mass including a metal workpiece and polishing media is charged into the barrel tank 11 (step S21, mass charging step). This polishing media is a resin media containing a resin. Next, the mass is fluidized in the barrel tank (step S22, fluidization step), the workpiece is polished with a polishing medium, and a film is formed on the surface of the workpiece to provide a rust prevention function (S23, Polishing / rust prevention step) In this step 23, the workpiece collides with the polishing media, or the workpieces contact each other, or the workpiece contacts the wall surface of the barrel tank 11, and the workpiece is polished. Is done. In addition, a film containing the resin as a main component is formed on the surface of the workpiece by attaching the resin contained in the polishing media.

  Examples of the resin contained in the polishing media include thermoplastic resins (eg, polyamide, polystyrene, polycarbonate, ABS, polypropylene, polyamide, acrylonitrile / styrene, etc.) and thermosetting resins (eg, phenol resin, unsaturated polyester resin, polyurethane). Resin, epoxy resin, urea resin, etc.). Of these, nylon resin, which is a polyamide-based resin, is a highly polar material. Therefore, when a nylon resin film is formed on the surface of the workpiece, the overall water repellency is improved. As a result, a good rust prevention effect can be obtained. In addition, since nylon resin is an inexpensive material, the antirust effect can be improved while reducing the cost by including the nylon resin in the polishing media.

  The polishing media may be formed of only a resin, but may be formed of a resin in which abrasive grains are dispersed in order to increase the polishing ability. As the abrasive grains, powders or grains made of a known material such as alumina, silica, silicon carbide, iron oxide, silicon oxide, zircon, chromium oxide, diamond, and gold sand can be used. In the present embodiment, the abrasive powder is formed by dispersing alumina powder in the resin.

  Moreover, when the particle size of the abrasive grains is too small, the polishing power is insufficient, or the effect of dispersing the abrasive grains cannot be obtained. If it is too large, the holding force by the resin is weak, and the abrasive grains easily fall off during polishing, so that the polishing ability of the polishing media is remarkably lowered as the polishing time elapses. Based on this, the grain size of the abrasive grains when using a resin in which abrasive grains are dispersed is preferably 35 μm to 71 μm.

  The content of the abrasive grains is appropriately selected in consideration of the polishing ability required for the polishing media, the strength of the polishing media, the amount of resin adhered to the workpiece, and the like. If the content of abrasive grains is too small, the polishing ability is insufficient, or the effect of dispersing abrasive grains cannot be obtained. If the abrasive content is too high, the amount of resin will be relatively small, making it difficult for the resin to adhere to the workpiece or reducing the strength of the polishing media. Based on this, the content of abrasive grains when using a resin in which abrasive grains are dispersed is 65% by mass to 85% by mass (preferably 70% by mass to 80% by mass, more preferably 70% by mass) with respect to the polishing media. % To 75% by mass).

  The abrasive media of the present embodiment is a resin material (nylon) pellets and weighed so as to be in the range of 65% by mass to 85% by mass with respect to the whole. The particle size is defined by JIS R6001; Alumina-based abrasive grains having an average particle diameter d50 = 46 μm) were heated and kneaded to disperse the abrasive grains in the resin, and then molded into a triangular prism by an injection molding machine.

When the workpiece and the polishing media are charged into the barrel tank 11 and the barrel polishing apparatus 10 is operated, the mass becomes fluidized inside the barrel tank 11. Since the polishing media contacts the workpiece, polishing of the workpiece proceeds by the abrasive grains located on the surface of the polishing media. Further, when the polishing media comes into contact with the workpiece, the resin of the polishing media adheres to the surface of the workpiece. The inventor speculates that at least one of the following (1) and (2) occurs in this adhesion phenomenon.
(1) The contact point locally becomes high temperature due to the collision energy of the polishing media. The heat melts the resin of the polishing media and the resin adheres to the surface of the workpiece.
(2) When the polishing media is rubbed against the workpiece, the resin of the polishing media adheres to the surface of the workpiece due to friction.

  On the surface of the workpiece, rust is generated and progresses because the constituent material of the workpiece reacts with oxygen and moisture in the air. According to the barrel polishing method of the above embodiment, since the resin adheres to the surface of the workpiece, the chance that the surface is directly exposed to the outside air is reduced. Thereby, generation | occurrence | production of rust on the surface of a workpiece is suppressed. In order to prevent the generation of rust more completely, a resin layer (film) can be formed so as to cover the entire surface of the workpiece. Here, if the thickness of the coating is too small, it is difficult to sufficiently impart a rust prevention function to the workpiece. On the other hand, when the film is too thick, the dimensional accuracy of the workpiece is deteriorated, or the surface roughness is increased by the film, and the quality is deteriorated. Further, as the film becomes thicker, the adhesive force with the work piece becomes weaker and it becomes easier to peel off. For this reason, the thickness of the resin film formed on the surface of the workpiece is 0.1 to 10.0 nm (preferably 0.2 to 5.0 nm, more preferably 0.2 to 2.0 nm). can do.

(Second embodiment)
Next, another embodiment for imparting a rust prevention function to a workpiece and performing barrel polishing will be described as a second embodiment. In the following description, differences from the first embodiment will be described.

  In the barrel polishing method according to this embodiment, as in the barrel polishing method according to the first embodiment, first, a mass including a metal workpiece and polishing media is inserted into the barrel tank 11, and then the mass is barreled. The workpiece is polished with the polishing media by fluidizing in the tank. However, the barrel polishing method according to the present embodiment is different from the barrel polishing method according to the first embodiment in that the mass includes a rust preventive function imparting material in addition to the workpiece and the polishing media. In the present embodiment, the polishing media may not contain a resin. In the barrel polishing method according to the present embodiment, the workpiece is polished by the flowing polishing media colliding with the workpiece. Further, a component film constituting the rust preventive function-imparting material adheres to the surface of the workpiece, whereby a film of the component is formed.

  The rust preventive function-imparting material may be composed mainly of any one of resin, fatty acid sodium, and a salt of fatty acid sodium. Since the rust preventive function can be imparted to the workpiece by the rust preventive function imparting material, the material of the polishing media is not particularly limited. For example, as the polishing media of this embodiment, polishing media (resin media) composed of only resin or a resin in which abrasive grains are dispersed as in the first embodiment, kneaded abrasive grains and clay are baked. Selected appropriately from ceramic abrasive media (ceramic media) such as polished abrasive media (baked media) and abrasive media sintered together (sintered media), abrasive media made of metal (metal media), etc. be able to. In the barrel polishing method according to the present embodiment, since the material of the polishing media can be selected in accordance with the required finish level, the versatility is higher than in the first embodiment. In addition, the polishing media (resin media) of the first embodiment can be used to combine the formation of a film with a resin medium and the formation of a film with a rust preventive function-imparting material.

  When the main component of the rust preventive function-imparting material is a resin, a film of the resin can be formed on the surface of the workpiece as in the first embodiment. Can be granted. The resin used as the antirust function-imparting material can be appropriately selected from a thermoplastic resin and a thermosetting resin as in the first embodiment. As the resin, a nylon resin may be selected for the same reason as in the first embodiment.

  When the main component of the rust preventive function-imparting material is a fatty acid or a salt thereof, a higher rust preventive effect can be obtained as compared with the case where a rust preventive function-imparting material composed mainly of a resin is used. The reason is not clear, but it is assumed that a denser film is formed as compared with the resin film. Examples of the case where the main component of the rust preventive function-imparting material is a fatty acid include lauric acid and oleic acid. Examples of fatty acid salts include fatty acid metal salts such as fatty acid sodium, fatty acid magnesium, and fatty acid calcium, and fatty acid potassium. Among these fatty acids and fatty acid salts, particularly fatty acid sodium can impart a higher antirust function to the workpiece at a lower cost. Examples of fatty acids in fatty acid sodium when fatty acid sodium is used as the fatty acid salt include butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid. And ricinolenic acid. The fatty acid may be single or a mixture containing two or more.

  The rust prevention function-imparting material may be either a compact (pellet) having a size smaller than that of the abrasive media or a resin powder. When the rust preventive function-imparting material is a molded body, the surface of the workpiece can be further smoothed with the molded body, and at the same time, a film of the components constituting the molded body can be formed. If the size of the molded body is too large for the polishing media, the polishing with the polishing media is hindered. On the other hand, if the size is too small, the chance that the molded body comes into contact with the workpiece is reduced, so that it becomes difficult to impart a sufficient rust prevention function to the workpiece. Therefore, it is preferable that the size of the molded body is smaller in side or diameter than the abrasive media, and the volume of the molded body is 1/5 to 2/3 with respect to the abrasive media.

  When the rust preventive function-imparting material is a powder, when the abrasive media comes into contact with the workpiece, the powder is pressed against the surface of the workpiece, so that part of the powder is melted, and as a result, the surface of the workpiece is protected. Components constituting the rust function-imparting material adhere to form a film. However, it is difficult to form a film if the particle size of the powder is too large or too small. If it is too large, the decrease in melting point is small, so that the effect of powdering cannot be obtained, and if it is too small, the chance of contact with the work piece decreases. The particle diameter of the powder is preferably selected from the range of 50 to 100 μm (average particle diameter; d50).

  Moreover, even if the rust preventive function-imparting material is either a molded body or a powder, if the amount of charging to the polishing media is too large, polishing with the polishing media is inhibited, and if it is too small, the rust preventive function-imparting material Since the chance of contact with the workpiece is reduced, it is not possible to provide a sufficient rust prevention function to the workpiece. For example, when the rust preventive function-imparting material is a molded body, the apparent volume of the molded body with respect to the polishing media may be 1/5 to 1/2.

  Further, in addition to the work piece, the polishing media, and the rust preventive function imparting material, barrel polishing may be performed by further inserting abrasive grains into the barrel tank. In this case, the workpiece can be polished also by the abrasive grains charged in the barrel tank, so that the polishing accuracy can be adjusted, and a polishing medium having a low impact force with the workpiece (for example, In the case of using a plant-made polishing medium having a low specific gravity or a polishing medium having a relatively soft surface, the polishing power can be increased by the abrasive grains. In addition, when the workpiece has a three-dimensional shape, the corner portion can be polished well.

  The grain size and material of the abrasive grains charged in the barrel tank can be appropriately selected according to the degree of finish. The grain size of the abrasive grains can be selected from, for example, 18 μm to 25 μm. Examples of the material include alumina, silica, silicon carbide, iron oxide, silicon oxide, zircon, chromium oxide, diamond, and gold sand.

  Further, if the amount of abrasive grains is small, the effect of improving the polishing power by the abrasive grains cannot be obtained, and if it is large, the polishing by the polishing media is hindered. The amount of the abrasive grains charged is such that the apparent volume is 0.1 to 3.0% (preferably 0.1 to 2.0) of the apparent volume of the workpiece, the polishing media, and the rust preventive function-imparting material. %).

(Example)
Next, the result of polishing by the barrel polishing method of the first embodiment and the second embodiment will be described. Workpieces (SUJ2 material or SS400 material having a diameter of 6 mm × height of 8 mm) and polishing media were respectively charged in four barrel tanks of a centrifugal barrel polishing machine (Shinto Kogyo Co., Ltd .; EC-2). The polishing media used are shown below.
Abrasive medium A: A triangular prism-shaped abrasive medium having a side of 7 mm formed of nylon resin in which alumina-based abrasive grains are dispersed.
Abrasive media B: Triangular prism-shaped abrasive media with a side of 7 mm formed only of nylon resin. Abrasive media C; Triangular prism-shaped abrasive media with a side of 7 mm formed of polystyrene in which abrasive grains are dispersed.
Polishing medium D: Triangular prism-shaped polishing medium with a side of 7 mm made of polycarbonate in which alumina abrasive grains are dispersed.
Polishing medium E: Triangular prism-shaped polishing medium having a side of 7 mm and formed of an ABS resin in which alumina abrasive grains are dispersed.
Abrasive media F; sintered media (manufactured by Shinto Kogyo Co., Ltd .; V7-EG 10 × 7)
Polishing media G: Firing media (manufactured by Shinto Kogyo Co., Ltd .; AFT 10 × 7)

Further, depending on the experimental conditions, a rust preventive function-imparting material and abrasive grains (manufactured by Shinto Kogyo Co .; WA # 800) were further charged. The used antirust function-providing materials are shown below.
Antirust function-providing material A: nylon resin powder (average particle size: 250 μm)
Antirust function-providing material B: Nylon resin molded body (7 mm x 7 mm x 7 mm)
Antirust function-providing material C: Fatty acid sodium powder (average particle size: 250 μm)
Rust prevention function imparting material D; molded body of sodium fatty acid (7 mm x 7 mm x 7 mm)

  The workpiece was polished by operating the centrifugal barrel polishing machine for a predetermined time. Then, five workpieces taken out from the barrel tank are selected, and the surface of the workpiece is washed by putting it into a water tank in which water is agitated, and then a dryer (manufactured by Tanaka Giken Co., Ltd .; TB -18H) at 100 ° C. Thereafter, evaluation of the film, evaluation of polishing, and evaluation of rust prevention were performed.

For the evaluation of the film, spectrum analysis and surface analysis (mapping) were performed by TOF-SIMS (manufactured by ULVAC-PHI Co., Ltd .; TRIFT5), and the presence or absence of the film and the type of the film were evaluated.
The film thickness was calculated by converting the value measured by XPS (X-ray photoelectron spectroscopy) into SiO ₂ . The specific measurement method is as follows.
The surface of the workpiece on which the film is formed is sputtered using argon ions as a light source, and the ions that are ejected are analyzed by XPS. When the sputtering rate r of the coating component, the time when the coating component cannot be detected, or the time when the substance of the workpiece is detected is the sputtering time t, the sputtering depth d, which is the thickness of the coating component, is d = r. Calculated by xt. Here, when a substance whose sputtering rate r is not known is measured, the sputtering depth d is generally calculated using the sputtering rate of SiO ₂ which is a standard sample, and this is used as the sputtering depth of the film.
Since the sputtering rate of the coating component of this example is not known, the thickness of the film was determined by using the sputtering depth calculated using the sputtering rate of SiO ₂ as described above.

  For the evaluation of polishing, the surface roughness Ra of the workpiece after drying (specified in JIS B6001; 1994) is measured with a surface roughness measuring instrument (manufactured by Tokyo Seimitsu Co., Ltd .; Surfcom 1500DX), and the average value is obtained. It was calculated and evaluated by comparing this value with the surface roughness of the green product.

The rust prevention was evaluated by leaving the dried workpiece in a constant temperature and humidity chamber maintained in a predetermined atmosphere and observing the progress of rust. Specifically, the inside atmosphere was left in a constant temperature and humidity chamber (manufactured by Enomoto Kasei Co., Ltd .; TH403HE) maintained at a temperature of 49 ° C. and a humidity of 95% via a resin mount. This sample was observed with a microscope (manufactured by Hilox Co., Ltd .; KH3000) every 72 hours after 72 hours, and the progress of rust was visually evaluated. The evaluation criteria were as follows.
○ ・ ・ ・ No rust confirmed.
Δ: Rust was observed, but all sizes were less than 0.5 mm.
X: Rust of 0.5 mm or more was observed.

  The processing conditions in Examples 1 to 22 and Comparative Examples 1 and 2 were as shown in Table 1. Table 1 shows the evaluation results of the workpieces obtained in Examples 1 to 22 and Comparative Examples 1 and 2. In Table 1, “particle size” refers to the particle size of the abrasive grains dispersed in the resin, and “abrasive content” refers to the content (% by mass) of the abrasive grains relative to the polishing media in the polishing media containing the resin.

(1) Evaluation of film When polished using a polishing medium containing a resin and when a rust preventive function-imparting material is charged and polished, the surface of the workpiece is 0.1 nm to 10 nm. A film of 0.0 nm was formed (Examples 1 to 22). On the other hand, when the polishing was performed only with the ceramic media as in Comparative Examples 1 and 2, no film was formed on the surface of the workpiece. As a result, it was found that an extremely thin film can be formed on the surface of the workpiece by the barrel polishing method of the example.
As an example of this evaluation result in the first embodiment, the analysis result of Example 1 is shown in FIG. FIG. 4A shows the result of spectral analysis of negative ions on the surface of the workpiece. Molecular ion peaks were detected when the mass-to-charge ratio (m / z) was 17, 26, 42, and 80 (circled points in the figure). These indicate that OH ⁻ ions, CN ⁻ ions, CNO ⁻ ions, and SO ₃ ²⁻ ions were detected, respectively. Among these, CN ^- ion and CNO ^- ion are ions derived from nylon. Other ions, OH ⁻ ions are general substances existing in the air, and SO ₃ ²⁻ ions are substances derived from the barrel tank. FIG. 4B shows the result of surface analysis (mapping) of the surface of the workpiece. The white or gray part indicates that the target ion has been detected. As shown in the figure, it was shown that CN ⁻ ions and CNO ⁻ ions exist on the entire surface of the workpiece. From the above results, it was found that when polishing was performed by the barrel polishing method of the first embodiment, a resin film was formed on the surface of the workpiece.

  Moreover, the analysis result of Example 20 is shown in FIG. 5 as an example of this evaluation result in 2nd embodiment. FIG. 5A shows the spectrum analysis result of positive ions of the workpiece. For comparison, the lower part shows a spectrum analysis result of an unprocessed workpiece. Molecular ion peaks were detected when the mass-to-charge ratio was 101, 105, 111, 115, 121, and 128 (Δ points in the figure) for the unprocessed workpiece, but for the workpiece of Example 17, the above-described workpiece was processed. In the mass-to-charge ratio, molecular ion peaks were not detected, but were detected in the cases of 104, 113, 117, 127, and 129 (circled points in the figure). This mass-to-charge ratio indicates a component derived from sodium fatty acid used as a rust preventive function-imparting material. This result suggests that a film of the antirust function-imparting material is formed on the surface of the workpiece by inserting and polishing the antirust function-imparting material. FIG. 5B shows the result of surface analysis of the surface of the workpiece. In this figure, ions having a mass-to-charge ratio of 127 are detected. As shown in the figure, this ion was found to be present on the entire surface of the workpiece. From the above results, it was found that when barrel polishing was performed by the barrel polishing method of the second embodiment, a film of a rust preventive function-imparting material was formed on the surface of the workpiece.

(2) Evaluation of polishing The surface roughness Ra of the workpiece before polishing was 0.15 μm for both the SUJ2 material and the SS400 material. In contrast, when polishing is performed using a polishing medium in which abrasive grains are dispersed in a resin (Examples 1 to 10, 13 to 15, and 22), the surface roughness Ra of the workpiece after polishing is 0.00. Since it was 07 μm to 0.12 μm, it was polished well under any conditions. When polishing is performed using a polishing medium formed only of nylon resin, the polishing ability is inferior to that of Examples 1 to 10 because abrasive grains are not contained as shown in Examples 11 and 12. However, since the surface roughness is smaller than that of the unprocessed product, it can be seen that this type B polishing media was also polished. Moreover, it turned out that grinding | polishing is progressing compared with Example 10 in Example 19 which inserted and grind | polished the abrasive grain using this grinding | polishing media.
When polishing was performed using ceramic media (Comparative Examples 1 and 2), the surface roughness Ra of the workpiece after polishing was 0.29 μm to 0.30 μm. This is presumably because ceramic media is harder than resin media and therefore has a strong impact force on the workpiece. However, when the rust preventive function-imparting material was further charged into the barrel tank and polished, it was 0.09 μm to 0.20 μm. This is because the surface of the polishing media was formed with the rust-proofing material, which improved the lubricity of the polishing media itself and reduced the impact force when the polishing media collided with the workpiece. It is guessed that. In particular, when fatty acid sodium is used as a material for imparting rust prevention function (Examples 19 to 21), the surface roughness is 0.07 μm to 0.10 μm, and the surface roughness is equivalent to that of polishing with a resin medium. It turns out that improved. That is, when the rust preventive function-imparting material is inserted into the barrel tank, a lubricity imparting step of imparting lubricity to the surface of the polishing media by forming a non-wetting film on the surface of the polishing media can be further provided. By providing this process, finishing performance (surface roughness, shape adjustment, etc.) equivalent to or close to polishing with resin media can be obtained. In the polishing conditions of this example, no difference in the surface roughness due to the difference in the material of the workpiece was observed.

(3) Evaluation of rust prevention Workpieces that have not been barrel-polished (unprocessed products 1 and 2) have already been rusted when left for 72 hours after the start of observation. Rust progressed, and rust of 0.5 mm or more was observed after 312 hours. On the other hand, when it grind | polishes using the grinding | polishing media containing a nylon resin, as shown in Examples 1-12, rust is not observed or even if rust is observed, intensity | strength and dimensional accuracy are not affected. Only rust of less than 5 mm was observed, and it was found that corrosion did not progress over time. When the film thickness of the resin film is increased, rust is less likely to occur, but when the film thickness is further increased, rust is more likely to occur (Example 9). This is presumed to be due to the peeling of the coating once coated in the course of increasing the film thickness.

  When polishing is performed using a polishing medium containing a resin other than nylon resin, as shown in Examples 13 to 15, time when rust is generated as compared to the case of using a polishing medium containing nylon resin (Examples 1 to 10). Was early, but the evaluation of rust was ○ or Δ. It has been found that a rust preventive function can be imparted to a workpiece even when polishing is performed using a polishing medium having a structure containing a resin other than nylon.

  In the case of polishing using ceramic media, as shown in Comparative Examples 1 and 2, the evaluation was x in 96 hours and 72 hours. It was also found that rust is more likely to occur than unprocessed products. On the other hand, when the rust preventive function-imparting material mainly composed of nylon resin is inserted and polished, as shown in Examples 16 to 18, when polished under the same conditions as polishing media containing nylon resin (implemented) Compared with Example 7), the time for rust generation was earlier, but the same or better rust prevention effect was obtained than other conditions. In particular, the form of the rust preventive function-imparting material had a superior rust preventive effect with the molded body.

  When the rust preventive function-imparting material containing fatty acid sodium as a main component is charged and polished, as shown in Examples 16 to 18, when polished under the same conditions as polishing media containing nylon resin (Example 7), And the rust prevention effect superior to the case (Examples 16-18) where the rust prevention function provision material which has nylon resin as a main component was inserted and grind | polished was acquired. In particular, the form of the rust preventive function-imparting material had a superior rust preventive effect with the molded body.

  When the rust preventive function-imparting material and the abrasive grains are charged and polished, as shown in Example 22, the polishing progresses and is superior to the case where only the same polishing medium is used (Example 12). Rust prevention effect was obtained.

  In addition, when comparing the case where the workpiece is SUJ2 material and SS400 material, there is no difference in the qualitative evaluation shown in Table 1 when polishing is performed under the same polishing conditions, but the SUJ2 is slightly rusted. There were few trends.

  As a result, it was found that by polishing the workpiece with a polishing medium containing a resin, the workpiece can be polished and simultaneously provided with a rust prevention function.

In the above description, “red rust (Fe ₂ O ₃ )” has been described as an example of rust generated on the workpiece. However, the method of the present invention is applicable to corrosion products generated when “black rust (Fe ₃ O ₄ )” or a non-ferrous metal is used as a workpiece (for example, “greenish blue” generated in the case of copper, tin or aluminum). In the case of (2), it can also be suitably used for suppressing the occurrence of “white rust” and the like.

  In the embodiment, the barrel polishing method using the centrifugal barrel polishing apparatus has been described, but the barrel polishing apparatus used in the method of the present invention is not limited to this. “Flow barrel polishing device” that fluidizes and polishes mass by rotating a rotating plate provided at the bottom of the polishing device, and “vibration barrel polishing device” that fluidizes and polishes mass by vibrating a barrel tank It can be applied to polishing by any barrel polishing apparatus.

  In the embodiment, the lubricity imparting step using the rust preventive function imparting material has been described for the case of polishing with a ceramic medium, but it can also be provided for the case of polishing with a metal medium.

  The barrel polishing method of the present invention has a lower rust prevention effect than dry barrel polishing, but can also be applied to wet barrel polishing.

10 Centrifugal barrel polisher 11 Barrel tank 12 Barrel tank case 12a Rotating shaft 13 Turret (revolving disk)
13a bearing 14 revolving shaft 15 drive mechanism 15a drive motor 15b motor pulley 15c revolving pulley 15d drive belt 16 driven mechanism 16a drive pulley 16b driven pulley 16c driven belt

Claims (11)

A barrel polishing method in which a mass including a workpiece and an abrasive medium is fluidized to polish the workpiece in a dry process,
A mass charging step of charging the mass into a barrel tank;
Fluidizing step of fluidizing the mass in the barrel tank;
Polishing and rust prevention step of polishing the workpiece with the polishing media and forming a film on the surface of the workpiece to give a rust prevention function,
A barrel polishing method comprising:   The barrel polishing method according to claim 1, wherein in the polishing / rust prevention step, the film having a thickness of 0.1 to 10.0 nm is formed. The polishing media is configured by dispersing abrasive grains in a resin,
In the polishing / rust prevention step, the workpiece is polished with the polishing media and a resin film is formed on the surface of the workpiece by the resin contained in the polishing media to provide a rust prevention function. The barrel polishing method according to claim 1 or 2. The mass further includes a rust preventive function-imparting material that is a powder or a molded body,
In the polishing / rust prevention step, the workpiece is polished with the polishing media and a film of a component constituting the rust prevention function-imparting material is formed on the surface of the workpiece by the rust prevention function-imparting material. The barrel polishing method according to claim 1 or 2, wherein a function is imparted.   The barrel polishing method according to claim 4, wherein the rust preventive function-imparting material is composed mainly of a resin.   The barrel polishing method according to claim 3, wherein the resin contains nylon as a main component.   The barrel-polishing method according to claim 4, wherein the rust prevention function-imparting material is composed of a fatty acid or a salt thereof as a main component.   The barrel polishing method according to claim 7, wherein the fatty acid or a salt thereof contains sodium fatty acid. The mass further includes abrasive grains,
In the polishing and rust prevention step, the workpiece is polished with the polishing media and the abrasive grains, and a film of the main component of the rust prevention function imparting material is formed on the surface of the workpiece by the rust prevention function imparting material. The barrel polishing method according to any one of claims 4 to 8, wherein the method is a barrel polishing method.   5. The barrel polishing method according to claim 4, further comprising a step of forming a non-wetting film on the surface of the polishing media and imparting lubricity to the surface of the polishing media by the rust prevention function-imparting material. . A barrel polishing method for polishing a workpiece by fluidizing a mass charged into a barrel tank,
Charging the barrel tank with a mass containing a workpiece and a polishing media based on a resin; and
Fluidizing the mass;
Polishing the workpiece with the polishing media and imparting a rust preventive effect to the surface of the workpiece with a resin that is a base of the polishing media;
A barrel polishing method comprising:

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