Patent Publication Number: US-2016236322-A1

Title: Polishing device, processing method of polishing member, modification method of polishing member, shape processing cutting tool, and surface modification tool

Description:
TECHNICAL FIELD 
     The present invention relates to a polishing device, a method for processing a polishing member, a method for modifying the polishing member, a shape-processing cutting tool, and a surface modifying tool. 
     BACKGROUND ART 
     Patent document 1 describes that when a portion to be polished of a workpiece (object to be polished) is polished with a polishing member, the shape of a polishing surface of the polishing member gradually changes. Generally, dressing is performed to modify the polishing surface and return it to its original shape. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: Japanese Laid-Open Patent Publication No. 11-188590 
       
    
     SUMMARY OF THE INVENTION 
     Problems that are to be Solved by the Invention 
     In the prior art, dressing is often performed to modify a planar polishing surface. Little consideration is made to the dressing of polishing surfaces having various shapes in conformance with the shapes of portions to be polished of workpieces. 
     The present invention is made in view of such circumstances, and its objective is to provide a polishing device, a method for processing a polishing member, and a method for modifying the polishing member that allow shape processing and shape modification to be easily performed on a polishing surface having a non-planar shape. Also, it is an object of the present invention to provide a shape-processing cutting tool used in the polishing device or the processing method to process the shape of the polishing surface or a surface modifying tool used in the polishing device or the modification method to modify the polishing surface to be shaped in conformance with the shape of a portion to be polished. 
     Means for Solving the Problem 
     To solve the above problem, a polishing device includes a polishing member, a shape-processing cutting tool or a surface modifying tool, and a contact mechanism. The polishing member includes a polishing surface that is shaped in conformance with the shape of a portion to be polished of a workpiece. The shape-processing tool has the same shape as the portion to be polished and processes the polishing surface to be shaped in conformance with the shape of the portion to be polished. The surface modifying tool has the same shape as the portion to be polished and modifies the polishing surface to be shaped in conformance with the shape of the portion to be polished. The contact mechanism brings the shape-processing cutting tool or the surface modifying tool into contact with the polishing surface. 
     In this configuration, the polishing member includes a polishing surface that is shaped in conformance with the shape of a portion to be polished of a workpiece. Thus, the portion to be polished of the workpiece can be polished even when having a non-planar shape, for example, a curved surface or a triangular shape. 
     In this configuration, the contact mechanism brings a shape-processing cutting tool or a surface modifying tool into contact with the polishing surface. The shape-processing cutting tool has the same shape as the portion to be polished and processes the polishing surface to be shaped in conformance with the shape of the portion to be polished. The surface modifying tool has the same shape as the portion to be polished and modifies the polishing surface to be shaped in conformance with the shape of the portion to be polished. Thus, the polishing surface, which is in contact with the shape-processing cutting tool or the surface modifying tool, copies the shape of the shape-processing cutting tool or the surface modifying tool that has the same shape as the portion to be polished of the workpiece. This processes or modifies the polishing surface to be shaped in conformance with the shape of the portion to be polished of the workpiece. Although the polishing surface of the polishing member is shaped in conformance with the shape of the portion to be polished of the workpiece, the shape of the polishing surface and the shape of each of the shape-processing cutting tool and the surface modifying tool have the relationship in which one is concave and the other is convex. This allows the shape of the polishing surface having a non-planar shape to be easily processed or modified. 
     The portion to be polished of the workpiece and the shape-processing cutting tool or the surface modifying tool do not need to have exactly the same shape as each other and may have slightly different shapes from each other as long as no practical problem occurs. 
     The shape-processing cutting tool is configured to process the polishing surface of the polishing member and is not particularly limited as long as it includes a processing portion having higher hardness than the polishing surface of the polishing member. Specific examples include a processing tool including fixed abrasive grains, such as pellets or an electrodeposition whetstone, and a cutting tool, such as an end mill or a bit. 
     The surface modifying tool is configured to adjust the surface of the polishing member and to remove grime or deposition from the surface of the polishing member. Specific examples include a processing tool including fixed abrasive grains and a hard brush. 
     In the polishing device, the contact mechanism brings the shape-processing cutting tool or the surface modifying tool into contact with the polishing surface preferably in predetermined cycles. In this configuration, the polishing surface is processed or modified in each predetermined cycle. This appropriately maintains the accuracy for polishing the workpiece. 
     In the polishing device, it is preferable that through a process of bringing a surface of the polishing member that differs in shape from the portion to be polished into contact with the shape-processing cutting tool or the surface modifying tool, the polishing surface of the polishing member be formed to be shaped in conformance with the shape of the portion to be polished. 
     In this configuration, forming the polishing surface to be shaped in conformance with the shape of the portion to be polished of the workpiece is performed in the polishing device. Thus, the shape of the polishing surface may be formed with high accuracy compared to when the polishing member including the polishing surface that is formed in advance in conformance with the shape of the portion to be polished of the workpiece is coupled to the polishing device. 
     The polishing device preferably includes a motor that rotates the polishing member from below. The polishing device preferably includes a base including an upper surface. When the polishing member is located on the upper surface, the base is rotated integrally with the polishing member. These configurations obtain stable rotation of the polishing member with a small axial run-out and allows for polishing to be performed with higher accuracy. 
     When the polishing device includes a shape-processing cutting tool that has the same shape as the portion to be polished and processes the polishing surface to be shaped in conformance with the shape of the portion to be polished or a surface modifying tool that has the same shape as the portion to be polished and modifies the polishing surface to be shaped in conformance with the shape of the portion to be polished, the shape of the polishing surface having a non-planar shape can be easily processed or modified. 
     To solve the above problem, a method for processing or modifying a polishing member includes bringing a shape-processing cutting tool or a surface modifying tool into contact with a polishing surface of the polishing member. The polishing surface is shaped in conformance with the shape of a portion to be polished of a workpiece. The shape-processing cutting tool has the same shape as the portion to be polished and processes the polishing surface to be shaped in conformance with the shape of the portion to be polished. The surface modifying tool has the same shape as the portion to be polished and modifies the polishing surface to be shaped in conformance with the shape of the portion to be polished. 
     In this method, the polishing member is prepared that includes a polishing surface shaped in conformance with the shape of a portion to be polished of a workpiece. Thus, the portion to be polished of the workpiece can be polished even when having a non-planar shape, for example, a curved surface or a triangular shape. 
     In this method, the shape-processing cutting tool, which has the same shape as the portion to be polished and processes the polishing surface to be shaped in conformance with the shape of the portion to be polished, or the surface modifying tool, which has the same shape as the portion to be polished and modifies the polishing surface to be shaped in conformance with the portion to be polished, is brought into contact with the polishing surface. Thus, the polishing surface, which is in contact with the shape-processing cutting tool or the surface modifying tool, copies the shape of the shape-processing cutting tool or the surface modifying tool that has the same shape as the portion to be polished of the workpiece. This modifies the polishing surface to be shaped in conformance with the shape of the portion to be polished of the workpiece. Although the polishing surface of the polishing member is shaped in conformance with the shape of the portion to be polished of the workpiece, the shape of the polishing surface and the shape of each of the shape-processing cutting tool and the surface modifying tool have the relationship in which one is concave and the other is convex. This allows the shape of the polishing surface having a non-planar shape to be easily modified. 
     Effect of the Invention 
     The present invention succeeds in facilitating shape processing or shape modification of a polishing surface having a non-planar shape. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic plan view showing the structure of a polishing device according to one embodiment. 
         FIG. 2  is a schematic side view showing the structure of the polishing device of the embodiment. 
         FIG. 3  is a partial side view showing the polishing device of the embodiment when a shape-processing cutting tool or a surface modifying tool is in contact with a polishing member. 
         FIG. 4  is a partial side view showing the polishing device of the embodiment when the shape-processing cutting tool or the surface modifying tool is separated from the polishing member. 
         FIG. 5  is a schematic plan view showing the structure of a polishing device according to a modified example of the embodiment. 
         FIG. 6  is a side view showing the structure of a shape-processing cutting tool according to another modified example of the embodiment. 
         FIG. 7(A)  is a side view showing the structure of a shape-processing cutting tool according to another modified example of the embodiment. 
         FIG. 7(B)  is a cross-sectional view taken along line C-C. 
         FIG. 8  is a side view showing the structure of a surface modifying tool according to another modified example of the embodiment. 
         FIG. 9  is a side view showing the operation of a contact mechanism according to another modified example of the embodiment. 
         FIG. 10  is a side view showing the operation of the contact mechanism according to the modified example shown in  FIG. 9 . 
         FIG. 11  is a side view showing the operation of the contact mechanism according to the modified example shown in  FIG. 9 . 
         FIG. 12  is a perspective view showing a rod according to another modified example of the embodiment. 
         FIG. 13  is a plan view showing a polishing member according to the modified example shown in  FIG. 12 . 
         FIG. 14  is a side view showing a polishing member according to another modified example of the embodiment. 
         FIG. 15  is a plan view showing the polishing member according to the modified example shown in  FIG. 14 . 
         FIG. 16  is a side cross-sectional view showing the polishing member according to the modified example shown in  FIG. 14 . 
         FIG. 17  is a partial side view showing a workpiece and a polishing member according to another modified example of the embodiment. 
         FIG. 18  is a partial side view showing a workpiece and a polishing member according to another modified example of the embodiment. 
         FIG. 19  is a partial side view showing a workpiece and a polishing member according to another modified example of the embodiment. 
         FIG. 20  is a partial side view showing a workpiece and a polishing member according to another modified example of the embodiment. 
         FIG. 21  is a partial side view showing a workpiece and a polishing member according to another modified example of the embodiment. 
         FIG. 22  is a partial side view showing a polishing member according to another modified example of the embodiment. 
         FIG. 23  is a partial side view showing the polishing member according to the modified example shown in  FIG. 22 . 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     A polishing device, a method for modifying a polishing member, a shape-processing cutting tool, and a surface modifying tool according to one embodiment of the present invention will now be described with reference to  FIGS. 1 to 4 . 
     As shown in  FIG. 1 , the polishing device includes a discoid polishing member  10 . The polishing member  10  includes a radially outer circumferential surface that is used to polish an end KE of a workpiece K, which is a portion to be polished. The end KE is machined in advance to have a curved surface. The workpiece K may have any shape, for example, in accordance with its application. 
     Any optimal material for polishing the end KE may be used for the polishing member  10 . For example, when a resin is used as the material of the polishing member  10 , any synthetic resin may be used. Examples of such a synthetic resin include a thermosetting resin (phenol resin, epoxy resin, urethane resin, polyimide, etc.) and a thermoplastic resin (polyethylene, polypropylene, acrylic resin, polyamide, polycarbonate, etc.). Alternatively, a cloth, a non-woven fabric, a resin processed non-woven fabric, synthetic leather, or a composite thereof may be used. The polishing surface of the polishing member  10  preferably has a Shore A hardness of 5 or greater. When a polishing member  10  having a shore A hardness of 5 or greater, which is subject to hardness measurement, is left for 60 minutes or longer in a dry condition where the humidity is 20% to 60% under room temperature, the hardness of the polishing surface of the polishing member is then measured with a durometer (type A) that is compliance with JIS K6253, and the measured value is 5 or greater. When the Shore A hardness is 5 or greater, the surface of the workpiece K can be polished in a preferred manner. Further, deformation of the polishing surface of the polishing member  10  can be reduced that would be caused by polishing performed within a short period of time. 
     The Shore A hardness of the polishing surface of the polishing member  10  is preferably 40 or greater, more preferably 70 to 95, and particularly preferably 70 to 85. 
     When a metal is used as the material of the polishing member  10 , magnesium, aluminum, titanium, iron, nickel, cobalt copper, zinc, manganese, or an alloy of which the main component is any of these metals may be used. 
     When a resin or a metal is used as the material of the polishing member  10 , the polishing member  10  may include abrasive grains. The kind of the used abrasive grains is not particularly limited and may be metal oxide particles of silicon oxide, aluminum oxide, zirconium oxide, cerium oxide, magnesium oxide, calcium oxide, titanium oxide, manganese oxide, iron oxide, or chromium oxide; a carbide, such as silicon carbide; a nitride; a boride; or a diamond. 
     When a ceramic is used as the material of the polishing member  10 , any of ceramics and glass; any of an oxide, nitride, boride, and carbide of silicon, aluminum, zirconium, calcium, and barium; or any of aluminum oxide, zirconium oxide, silicon oxide, silicon carbide, silicon nitride, and boron nitride may be used. 
     Further, any material may be used for the workpiece K. For example, when a resin is used as the material of the workpiece K, any synthetic resin may be used. Examples of such a synthetic resin include a thermosetting resin (phenol resin, epoxy resin, urethane resin, polyimide, etc.) and a thermoplastic resin (polyethylene, polypropylene, acrylic resin, polyamide, polycarbonate, etc.). 
     When a ceramic is used as the material of the workpiece K, any of ceramics, glass, and fine ceramics; any of an oxide, carbide, nitride, and boride of silicon, aluminum, zirconium, calcium, and barium may be used. 
     When a metal is used as the material of the workpiece K, magnesium, aluminum, titanium, iron, nickel, cobalt, copper, zinc, manganese, or an alloy of which the main component is any of these metals may be used. 
     The workpiece K may be used for any purpose. For example, the workpiece K may be used as a wheel, a shaft, a container, a casing (for example, case and housing), a frame, a ball, a wire, an ornament, or the like. 
     As shown in  FIG. 2 , the polishing member  10  is fixed to the upper surface of a discoid base  20  in a removable manner. The lower surface of the base  20  includes a center portion that is fixed to a rotation shaft of a first motor  21 . When the first motor  21  is driven to be rotated, the base  20  and the polishing member  10  rotate. The first motor  21  is located below the polishing member  10  and the base  20 . The polishing member  10 , which is located on the upper surface of the base  20 , is rotated together with the base  20  from below. This obtains stable rotation of the polishing member  10  with a small axial run-out and allows for polishing to be performed with higher accuracy. 
     The radially outer circumferential surface of the polishing member  10  includes a polishing surface  11 , which is a curved grooved surface that circumferentially extends. The curvature of the polishing surface  11  is shaped in conformance with the shape of the end KE of the workpiece K (shape of portion to be polished). More specifically, the polishing surface  11  and the end KE have the same curvature. 
     The workpiece K is held by a fixing seat  32  in a removable manner. The fixing seat  32  is fixed to a rotation shaft  31  of a second motor  30 . The second motor  30  is coupled to a motor moving mechanism  33  that reciprocates the second motor  30  in directions orthogonal to a rotation axis of the polishing member  10  (directions of arrows X shown in  FIGS. 1 and 2 ). When the motor moving mechanism  33  moves the second motor  30 , the second motor  30 , the rotation shaft  31 , the fixing seat  32 , and the workpiece K are integrally move in the directions orthogonal to the rotation axis of the polishing member  10 . Such movement of the second motor  30  caused by the motor moving mechanism  33  presses the end KE of the workpiece K against the polishing surface  11 . Then, a contact portion of the end KE and the polishing surface  11  is appropriately supplied with, for example, a processing liquid, and each of the first motor  21  and the second motor  30  is driven at a predetermined rotation speed. This polishes the end KE having the curved surface. When pressing the end KE of the workpiece K against the polishing surface  11 , the pressing force is adjusted so that predetermined pressure is applied. 
     The processing liquid may be directly supplied to the contact portion of the end KE and the polishing surface  11  from the outer side. Alternatively, a processing liquid supply mechanism such as a rotary joint may be arranged in a portion that connects the polishing member  10  and the first motor  21 . When the processing liquid supply mechanism supplies the processing liquid into the polishing member  10 , the processing liquid may be supplied from the polishing member  10  to the contact portion through a supply passage formed in the polishing member  10 . When supplied from the inside of the polishing member  10  toward the contact portion, the processing liquid may be further efficiently supplied. Additionally, to efficiently use the processing liquid, it is further preferable that a cover be arranged around the polishing member  10  and that a collection device be provided to increase the efficiency for collecting the processing liquid. 
     A suitable kind of the processing liquid may be used in accordance with the material of the workpiece K to be polished and the polishing member  10 . Specifically, a cutting liquid, grinding liquid, a lapping material, a polishing agent, or a chemical mechanical polishing liquid may be used. The processing liquid may include abrasive grains. The kind of the used abrasive grains is not particularly limited and may be metal oxide particles of silicon oxide, aluminum oxide, zirconium oxide, cerium oxide, magnesium oxide, calcium oxide, titanium oxide, manganese oxide, iron oxide, or chromium oxide; a carbide, such as silicon carbide; a nitride; a boride; or a diamond. 
     For example, the amount of the abrasive grains contained in the processing liquid is preferably 1 mass percent or greater, and more preferably 2 mass percent or greater. The amount of the abrasive grains contained in the processing liquid is also preferably 50 mass percent or less, and more preferably 40 mass percent or less. 
     The abrasive grains in the processing liquid have an average secondary particle diameter of preferably 0.1 μm or greater, and more preferably 0.3 μm or greater. As the average secondary particle diameter of the abrasive grains increases, the processing liquid improves the processing speed. 
     Additionally, the average secondary particle diameter of the abrasive grains in the processing liquid is preferably 20 μm or less, and more preferably 5 μm or less. As the average secondary particle diameter of the abrasive grains decreases in the processing liquid, the surface of the workpiece K can be further evenly polished. The average secondary particle diameter of the abrasive grains is a volume average particle diameter that is measured with a laser diffraction/scattering particle size distribution measurement instrument, such as “LA-950” manufactured by HORIBA, Ltd. 
     When necessary, the processing liquid may include another component such as a pH adjuster, an etching agent, an oxidant, a water-soluble polymer, a copolymer and a salt and derivative thereof, an anticorrosive, a chelating agent, a dispersant aid, an antiseptic, or a fungicide. 
     For example, a known acid, base, or a salt of them may be used as the pH adjuster. Examples of such an acid that can be used as the pH adjuster include an inorganic acid, such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, or phosphoric acid; and an organic acid, such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyricacid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, diglycolic acid, 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, methoxyacetic acid, methoxyphenylacetic acid, or phenoxyacetic acid. 
     Examples of such a base that can be used as the pH adjuster include an amine, such as aliphatic amine or aromatic amine; an organic base, such as quaternary ammonium hydroxide; an alkali metal hydroxide, such as potassium hydroxide; an alkaline earth metal hydroxide; and ammonia. 
     Instead of the above acid or in combination with the above acid, a salt of the above acid, such as an ammonium salt or an alkali metal salt, may be used as the pH adjuster. Such a pH adjuster is used to adjust the pH value of the processing liquid to the optimal value, which differs in accordance with the kind of the workpiece K to be polished. 
     Examples of the etching agent include an inorganic acid, such as nitric acid, sulfuric acid, or phosphoric acid; an organic acid, such as acetic acid, citric acid, tartaric acid, or methanesulfonic acid; an inorganic alkali, such as potassium hydroxide or sodium hydroxide; and an organic alkali, such as ammonia, amine, or quaternary ammonium hydroxide. 
     Examples of the oxidant include hydrogen peroxide, peracetic acid, a percarbonate, urea peroxide, a perchlorate, a persulfate, an oxoacid, such as sulfuric acid, nitric acid, or phosphoric acid, and a salt of the oxoacid. 
     Examples of the water-soluble polymer, the copolymer and the salt and derivative thereof include a polycarboxylic acid, such as a polyacrylate; a polysulfonic acid, such as polyphosphonic acid or polystyrenesulfonic acid; a polysaccharide, such as xanthan gum or sodium alginate; a cellulose derivative, such as hydroxyethyl cellulose or carboxymethyl cellulose; polyethylene glycol; polyvinyl alcohol; polyvinylpyrrolidone; sorbitan monooleate; an oxyalkylene-based polymer having one or more kinds of oxyalkylene unit; a non-ionic surfactant; and an anionic surfactant. Examples of the non-ionic surfactant include polyoxyethylene alkylether, polyoxyethylene alkylphenylether, sorbitan monooleate, and an oxyalkylene-based polymer having one or more kinds of oxyalkylene unit. Examples of the anionic surfactant include an alkylsulfonic acid-based compound, an alkylbenzenesulfonic acid-based compound, an alkylnaphthalenesulfonic acid-based compound, a methyltaurine acid-based compound, an alkyldiphenyletherdisulfonic acid-based compound, an α-olefinsulfonic acid-based compound, a naphthalenesulfonic acid condensate, and a sulfosuccinic acid diester-based compound. 
     Examples of the anticorrosive include a monocyclic compound, a polycyclic compound having a condensed ring, and heterocyclic compound, such as an amine, a pyridine, a tetraphenylphosphonium salt, a benzotriazole, a triazole, a tetrazole, or benzoic acid. 
     Examples of the chelating agent include a carboxylic acid-based chelating agent, such as gluconic acid; an amine-based chelating agent, such as ethylenediamine, diethylenetriamine, or trimethyltetraamine; polyaminopolycarbon-based chelating agent, such as ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, triethylenetetraminehexaacetic acid, or diethylenetriaminepentaacetic acid; an organic phosphonic acid-based chelating agent, such as 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, methanehydroxyphosphonic acid, or 1-phosphonobutan-2,3,4-tricarboxylic acid; a phenol derivative; and 1,3-diketone. 
     Examples of the dispersant aid include a condensed phosphate, such as pyrophosphate or hexametaphosphate. 
     Examples of the antiseptic include sodium hypochlorite. 
     Examples of the fungicide include an oxazoline, such as oxazolidine-2,5-dione. 
     When the diameter of the polishing member  10  is maximized within a range in which the polishing accuracy is appropriately maintained, ends KE of workpieces K may be simultaneously polished with the circumferential surface of the polishing member  10 . This improves the productivity. Additionally, the maximum diameter of the polishing member  10  increases the linear velocity of the polishing member  10  at the outer circumference even when the rotation speed of the polishing member  10  is the same. This obtains the sufficient linear velocity for the polishing even when the rotation speed of the polishing member  10  is relatively decreased. Thus, for example, dispersion of the processing liquid may be reduced. 
     As shown in  FIG. 1 , a contact mechanism  40  is located at a position that is proximate to the radially outer circumferential surface of the polishing member  10  and opposed to the polishing surface  11 . 
     The contact mechanism  40  includes a tool  41 . The tool  41  is rod-shaped and includes a distal processing portion. The processing portion is shaped in conformance with the shape of the end KE and, more specifically, has the same curvature as the end KE. The tool  41  functions as a shape-processing cutting tool that processes the polishing surface  11  to be shaped in conformance with the shape of the end KE or a surface modifying tool that modifies the polishing surface  11  to be shaped in conformance with the shape of the end KE. An optimal material for processing or modifying the polishing surface  11  is selected for the tool  41 . The end KE of the workpiece K to be polished and the tool  41  do not need to have exactly the same shape as each other and may have slightly different shapes from each other as long as no practical problem occurs. 
     The contact mechanism  40  also includes a holder  42 , to which the tool  41  is fixed in a removable manner, and a moving mechanism  43  that reciprocates the holder  42  in directions (directions of arrows M shown in  FIG. 1 ) orthogonal to the rotation axis of the polishing member  10 . The drive source of the moving mechanism  43  may be electric power or hydraulic pressure. The moving mechanism  43  may be automatically driven by a controller including, for example, a CPU, a RAM, and a ROM or may be driven, for example, when the operator of the polishing device operates a switch. 
       FIGS. 3 and 4  show the operation of the contact mechanism  40 . 
     As shown in  FIG. 3 , when the contact mechanism  40  moves the holder  42  toward the rotation center of the polishing member  10  (in direction of arrow M 1 ), the tool  41  contacts the polishing surface  11 . More specifically, the tool  41  is pressed against the polishing surface  11 . 
     When pressing the tool  41  against the polishing surface  11 , a constant pressure processing can be performed. However, a constant dimension processing (constant dimension cutting) is more preferable. In the constant pressure processing, which is mainly used to improve surface roughness, the tool  41  is pressed against the polishing surface  11  at a constant pressing force when polishing. In the constant dimension processing, which is mainly used to finish the shape, the tool  41  is cut into the polishing surface  11  by a constant dimension. The constant dimension processing, which is suitable for the shape finishing, is suitable when modifying or processing the shape of the polishing surface  11  with the tool  41 . Thus, the shape may be further accurately modified or processed compared to the constant pressure processing. 
     The constant pressure processing may be performed when modifying or processing the shape of the polishing surface  11  with the tool  41 . In this case, the processing may be performed, for example, to improve the accuracy of the surface roughness of the workpiece K, and is suitable mainly when the tool  41  is the surface modifying tool and modifies the polishing surface  11 . 
     As shown in  FIG. 4 , when the contact mechanism  40  moves the holder  42  in a direction (direction of arrow M 2 ) separated away from the rotation center of the polishing member  10 , the tool  41  is separated away from the polishing surface  11 . 
     The tool  41  is normally located in a position separated from the polishing surface  11  as shown in  FIG. 4 . While the polishing member  10  is driven to be rotated, the tool  41  is moved to the position shown in  FIG. 3 , where the tool  41  contacts the polishing surface  11 , in each predetermined cycle, for example, when an accumulated value of polishing time exceeds a predetermined value or when the operator operates a switch. 
     When the tool  41  is in contact with the polishing surface  11 , it is preferred that water or the processing liquid be supplied to the contact portion of the tool  41  and the polishing surface  11 . This helps the processing or modification of the polishing surface  11  performed by the tool  41  and cools the contact portion. 
     Any appropriate kind of the used processing liquid may be selected in accordance with the kind of the shape-processing cutting tool or the surface modifying tool or the material of the polishing member. For example, when a cutting tool is used, a processing liquid for cutting may be applied. When a processing tool including fixed abrasive grains is used, a processing liquid for grinding may be applied. When a hard brush is used, for example, a cleaning liquid may be applied. 
     The present embodiment has the advantages described below. 
     (1) The polishing device includes a polishing member  10  having a polishing surface  11  shaped in conformance with the shape of an end KE of a workpiece K to be polished. Thus, even when the end KE of the workpiece K has a non-planar surface, or a curved surface, the end KE can be polished. 
     (2) The polishing device includes a tool  41  and a contact mechanism  40 . The tool  41 , which has the same shape as the end KE, modifies or processes the polishing surface  11  to be shaped in conformance with the shape of the end KE. The contact mechanism  40  brings the tool  41  into contact with the polishing surface  11 . Thus, as shown in  FIG. 3 , when in contact with the tool  41 , the polishing surface  11  copies the shape of the tool  41 , which has the same curvature as the shape of the end KE of the workpiece K. This modifies or processes the polishing surface  11  to be shaped in conformance with the shape of the end KE of the workpiece K. 
     The polishing surface  11  of the polishing member  10  is shaped in conformance with the shape of the end KE of the workpiece K. However, the shape of the polishing surface  11  and the shape of the tool  41  have the relationship in which one is concave and the other is convex. This allows the shape processing or shape modification to be easily performed on the polishing surface  11  that is non-planar, or curved. 
     (3) The contact mechanism  40  brings the tool  41  into contact with the polishing surface  11  in each predetermined cycle. Thus, the polishing surface  11  is modified in each predetermined cycle. This maintains the accuracy for polishing the end KE of the workpiece K for a long time. 
     The above embodiment may be modified as follows. 
     The tool  41  may modify the polishing surface  11  during an interval between the polishing of the workpiece K. Alternatively, the tool  41  may modify the polishing surface  11  at the same time as when polishing the workpiece K for the entire time or a partial time of polishing. 
     The shape-processing cutting tool is configured to process the polishing surface of the polishing member and is not particularly limited as long as it includes a processing portion having higher hardness than the polishing surface of the polishing member. Specific examples include a processing tool including fixed abrasive grains, such as pellets or an electrodeposition whetstones, and a cutting tool, such as an end mill or a bit. 
     When the electrodeposition whetstone is used, the abrasive grains may fall off when grinding the polishing surface  11  of the polishing member  10 . This may damage the surface of the workpiece K. One needs to pay attention to such damages particularly when grinding the polishing surface  11  with the electrodeposition whetstone during the polishing of the workpiece K with the polishing member  10 . In this regard, the surface of the electrodeposition whetstone may be coated with a hard layer, for example, diamond-like carbon (DLC). This limits fall-off of the abrasive grains and damages such as that describe above. 
     The surface modifying tool is configured to adjust the surface of the polishing member and to remove grime or deposition from the surface of the polishing member. Specific examples include a processing tool including fixed abrasive grains and a hard brush. 
     As shown in  FIG. 5 , a rotary cutter may be used as the tool  41 , which functions as the shape-processing cutting tool or the surface modifying tool. The rotary cutter includes an outer circumferential blade that has the same shape as the end KE of the workpiece K to be polished and modifies the polishing surface  11  to be shaped in conformance with the shape of the end KE. 
       FIG. 5  shows the schematic structure of this modified example of the polishing device. As shown in  FIG. 5 , a contact mechanism  60  is located at a position that is proximate to the radially outer circumference surface of the polishing member  10  and opposed to the polishing surface  11 . The contact mechanism  60  includes a cutter  50  such as that described above and a moving mechanism that reciprocates a rotation axis of the cutter  50  in directions (directions of arrows M shown in  FIG. 5 ) orthogonal to the rotation axis of the polishing member  10 . When the contact mechanism  60  moves the cutter  50  toward the rotation center of the polishing member  10  (in direction of arrow Ml), the blade of the cutter  50  contacts the polishing surface  11  as indicated by the double-dashed line shown in  FIG. 5 . When the contact mechanism  60  moves the cutter  50  in a direction separated away from the rotation center of the polishing member  10  (in direction of arrow M 2 ), the blade of the cutter  50  is separated from the polishing surface  11 . In this modified example, the shape of the polishing surface  11  and the shape of the blade of the cutter  50  also have the relationship in which one is concave and the other is convex. This allows for the easy shape modification of the polishing surface  11  that is non-planar, or curved. 
     A tool other than the tool  41  may be used as the tool functioning as the shape-processing cutting tool or the surface modifying tool. Such modified examples will now be described below. 
       FIG. 6  shows a tubular shape-processing cutting tool  200  including a plurality of cutting blades  210  that axially extend and are circumferentially arranged at intervals. The shape-processing cutting tool  200  includes a distal portion  210   a  in which the external shape of the cutting blades  210  has the same curvature as the end KE. When the shape-processing cutting tool  200  is used instead of the tool  41 , the distal portion  210   a  comes in contact with the polishing surface  11  as the shape-processing cutting tool  200  rotates. This processes the polishing surface  11  of the polishing member  10  to be shaped in conformance with the shape of the end KE. 
       FIGS. 7(A) and 7(B)  show a flat shape-processing cutting tool  300  that includes a round cutting blade having the same curvature as the end KE defining a distal portion  310 . As shown in  FIG. 7(B) , the shape-processing cutting tool  300  is thinned toward the distal portion  310 . When the shape-processing cutting tool  300  is used instead of the tool  41 , the distal portion  310  comes in contact with the polishing surface  11  as the shape-processing cutting tool  300  rotates. This processes the polishing surface  11  of the polishing member  10  to be shaped in conformance with the shape of the end KE. A plurality of flat shape-processing cutting tools  300  may be combined. The flat shape-processing cutting tools  300  may be combined so that the flat shape-processing cutting tools  300  intersect with one another at a predetermined angle, such as 60° or 90°. 
       FIG. 8  shows a tubular surface modifying tool  400  including a distal hard brush  410 . The distal shape of the brush  410  is semispherical as a whole. The semispherical shape has substantially the same curvature as the end KE. When the surface modifying tool  400  is used instead of the tool  41 , the brush  410  comes in contact with the polishing surface  11  as the surface modifying tool  400  rotates. This modifies the polishing surface  11  of the polishing member  10  to be shaped in conformance with the shape of the end KE. 
     In the above embodiment, the polishing member  10  that is provided in advance with the curved polishing surface  11  is fixed to the base  20 . However, the polishing surface  11  may be formed using the shape-processing cutting tool. Thus, when a polishing member that is not shaped in conformance with the shape of the shape of a portion to be polished is prepared, the shape-processing cutting tool may be used to form a polishing surface in conformance with the shape of the portion to be polished of the workpiece. For example, as shown in  FIGS. 9 to 11 , the tool  41  may contact the circumferential surface of a polishing member  10 A that differs in shape from the end KE of the workpiece K to be polished and form the polishing surface  11  in conformance with the shape of the end KE. 
     More specifically, as shown in  FIG. 9 , the polishing member  10 A having a flat radially outer circumferential surface is fixed to the base  20 . As shown in  FIG. 10 , when the contact mechanism  40  moves the holder  42  toward the rotation center of the polishing member  10 A (in direction of arrow M 1 ), the tool  41  contacts the radially outer circumferential surface of the polishing member  10 A. More specifically, the tool  41  is pressed against the radially outer circumferential surface of the polishing member  10 A. The pressing of the tool  41  forms the polishing surface  11  in the flat outer circumferential surface of the polishing member  10 A. When forming the polishing surface  11 , it is also desirable to supply the processing liquid. After the polishing surface  11  is formed, as shown in  FIG. 11 , the contact mechanism  40  moves the holder  42  in a direction separated away from the rotation center of the polishing member  10 A (in direction of arrow M 2 ) to separate the tool  41  away from the polishing surface  11 . 
     In this modified example, forming the polishing surface  11  to be shaped in conformance with the shape of the end KE of the workpiece K is performed in the polishing device. Thus, the shape of the polishing surface  11  may be formed with high accuracy compared to when the polishing member  10  including the polishing surface  11  that is formed in advance in conformance with the shape of the end KE of the workpiece K is coupled to the polishing device. This eliminates the task for preparing the polishing member  10  that includes the polishing surface  11  in advance. 
     As shown in  FIG. 12 , a straight rod  70  includes a longitudinal side surface including a polishing surface  71 . The polishing surface  71  and the polishing surface  11  have similar shapes. Any material may be selected as the material of the rod  70 . It is preferable to use, for example, a material that is easily bent such as a synthetic resin or brass. 
     As shown in  FIG. 13 , the rod  70  is wound around a disk  80  so that the polishing surface  71  is opposed outward, and the wound rod  70  is fixed to the disk  80  in an appropriate manner. This forms a polishing member including the rod  70  and the disk  80 . A polishing member that is similar to the polishing member  10  is also formed through such a manner. Any material may be selected for the disk  80 . For example, a metal or ceramic may be used. However, the material is preferred to be as light as possible. 
     In the modified example shown in  FIGS. 12 and 13 , after the polishing surface  71  is formed in the rod  70 , the rod  70  is wound around the disk  80 . Instead, for example, after the straight rod  70  is wound around the disk  80 , the polishing surface  71  may be formed in the rod  70 . 
     In these modified examples, for example, when the polishing surface  71  has worn, only the rod  70  including the polishing surface  71  may be replaced. This reduces the replacement cost compared to the polishing member  10 . When polishing workpieces K each having a different shape of a portion to be polished, the different shapes of the portions to be polished may be easily coped with by replacing the rod 
     As shown in  FIG. 14 , a discoid polishing member  90  includes a radially outer circumferential surface including a curved surface  91  that circumferentially extends and is similar to the polishing surface  11 . The curved surface  91  may be applied or coated with a different member to form a polishing surface. As shown in  FIGS. 15 and 16 , for example, a tape-like non-woven fabric  100 , which will serve as a polishing surface, may be applied to the curved surface  91  formed in the radially outer circumferential surface of the polishing member  90 . In this case, the polishing surface may be renewed by replacing the non-woven fabric  100 . Thus, it is preferred that a material having relatively high durability, for example, a metal such as stainless steel be used as the material of the polishing member  90 . However, any material may be selected for the polishing member  90 . For example, when the polishing member  90  is formed from a metal, the curved surface  91  may undergo resin-coating to serve as a polishing surface. 
     The polishing member  10  is located on the upper surface of the base  20 . However, the base  20  may be omitted, and the rotation shaft of the first motor  21  may be directly fixed to the center of the polishing member  10 . 
     When the motor moving mechanism  33  is driven, the end KE is pressed against the polishing surface  11 . Instead, another mechanism for pressing the end KE against the polishing surface  11  may be included. 
     Instead of rotating the polishing member  10 , the polishing member  10  may be linearly reciprocated. 
     The end KE of the workpiece K is polished. However, the portion to be polished is not limited to such an end and may be a different portion. 
     The end KE of the workpiece K to be polished may have a non-planar shape other than a curved surface. For example, as shown in  FIG. 17 , the shape may be a triangle. Alternatively, as shown in  FIG. 18 , the shape may be a triangle with a round peak. Additionally, the end KE of the workpiece K to be polished may have the form of steps as shown in  FIG. 19  or the form of steps with round corners as shown in  FIG. 20 . Additionally, as shown in  FIG. 21 , the end KE may be recessed inward in the workpiece K. Further, a curve surface may have a plurality of curvatures or partially have a straight portion. In such modified examples, when the polishing surface  11  of the polishing member  10  is shaped in conformance with the shape of the end KE of the workpiece K (shape of portion to be polished), the end KE may be polished. 
     As shown in  FIG. 2 , in the embodiment, when the workpiece K is pressed against the polishing surface  11  in the direction orthogonal to the rotation axis of the polishing member  10  (direction of arrow X shown in  FIG. 2 ), the end KE of the workpiece K is polished. In this case, the pressed end KE is polished. However, the upper and lower surfaces of the workpiece K, that is, two surfaces of the workpiece K that are parallel to the planar orthogonal to the rotation axis of the polishing member  10 , do not receive much pressure when being polished and may fail to be sufficiently polished. 
     In this regard, the polishing member  10  is formed from a material such as a resin that has elasticity to a certain extent and elastically deforms. Then, as shown in  FIG. 22 , the width H 1  of the polishing surface  11  in a direction parallel to the rotation axis of the polishing member  10  (direction of arrow Y in  FIG. 22 ) is set less than the thickness T 1  of the workpiece K prior to the processing (i.e., length between upper surface KU and lower surface KD of workpiece K) by a predetermined amount α. Such an example, in which the polishing member  10  is formed by an elastic body and the polishing surface  11  is smaller in shape than the workpiece K to be polished, has the advantages described below. 
     As shown in  FIG. 23 , in this modified example, when the workpiece K is polished as being pressed against the polishing member  10 , pressing force F is applied to the upper surface KU and the lower surface KD of the workpiece K from the polishing member  10  that is elastically deformed by the predetermined amount α. This obtains an advantage such that when polishing the workpiece K, not only the end KE but also the upper surface KU and the lower surface KD are polished at the same time. As the predetermined amount α becomes larger, the elastic deformation amount of the polishing member  10  increases when polishing the workpiece K. Thus, the optimization of the predetermined amount α optimizes the pressing force F applied to the upper surface KU and the lower surface KD of the workpiece K to be polished. 
     When force pressing the end KE of the workpiece K against the polishing surface  11  and the pressing force F applied to the upper surface KU and the lower surface KD of the workpiece K are adjusted as necessary, the workpiece K may be appropriately processed. 
     DESCRIPTION OF REFERENCE CHARACTERS 
       10 ,  10 A,  90 : polishing member;  11 : polishing surface;  20 : base;  21 : first motor;  30 : second motor;  31 : rotation shaft;  32 : fixing seat;  33 : motor moving mechanism;  40 : contact mechanism;  41 : tool;  42 : holder;  43 : moving mechanism;  50 : cutter;  60 : contact mechanism;  70 : rod;  71 : polishing surface;  80 : disk;  91 : curved surface;  100 : non-woven fabric;  200 : shape-processing cutting tool;  210 : cutting blade;  210   a:  distal portion;  300 : shape-processing cutting tool;  310 : distal portion;  400 : surface modifying tool;  410 : brush; K: workpiece to be polished; KE: end (of workpiece); KU: upper surface (of workpiece); KD: lower surface (of workpiece).