JP2005246569A - Resinoid grinding wheel for mirror grinding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resinoid grinding wheel capable of performing a mirror grinding finishing by using a general purpose grinding machine. <P>SOLUTION: Bonding agent of a grinding wheel part 16 is made of bisphenol A based epoxy resin of a low elastic modulus and an organic hollow body 22 having a lower elastic modulus than that in resin bonding agent 20 is dispersed in the grinding wheel 16, and thereby large pressing force acting on abrasive grains 18a and 18b is transmitted to the organic hollow body 22 via the resin bonding agent 20 and the hollow body 22 is elastically pressed and contracted. The resin bonding agent 20 therefore is slightly and elastically deformed into a recessed shape in the vicinity of the grinding surface 34 to quickly retreat the abrasive grains 18a and 18b, and a distal end of the cutting edge is located on plane flush with the abrasive grain 18c. As a result, an outer peripheral surface 32 of a workpiece is not ground in an excessively projecting state of a part of the abrasive grain 18 to the grinding surface 34, and thereby generation of a crack is suppressed by the abrasive grain 18, and a mirror surface can be easily obtained by using even the general purpose grinding machine. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resinoid grindstone having fine superabrasive grains used for mirror finishing, and particularly to a rotary tool that can be used in a general-purpose grinder.

  High-hardness superabrasive grains, that is, diamond abrasive grains, CBN abrasive grains, and the like are used for grinding hard materials such as hardened materials, for example. Conventionally, when trying to obtain such a glossy smooth or mirror surface of hard material, a special processing machine such as loose abrasive processing such as lapping or polishing, or super finishing or barrel finishing is used. Processing has been done. In recent years, it has been attempted to perform mirror finishing with a general-purpose grinder using an abrasive-fixed rotary tool in which fine superabrasive grains are bonded with a binder instead of these.

  Conventionally, the above-described rotary tool for mirror finishing has been obtained by bonding abrasive grains with, for example, a glassy binder or a metallic binder, but these have a problem of poor truing properties and dressing properties. For this reason, special dressing devices such as the discharge method and the rotary method are used for truing and dressing of rotary tools used for processing that requires complicated grinding surface shapes, processing that frequently causes crushing and clogging, etc. It was necessary.

On the other hand, it has been proposed to use a resinoid grindstone that is easy to truing and dressing for precision grinding (see, for example, Patent Documents 2, 4, 5, etc.). Resinoid grindstones are generally used for rough machining with a large machining allowance because the load acting on the abrasive grains from the work material can be alleviated by the elastic deformation of the resin binder. To say. However, for example, it is difficult to maintain the shape of the ground surface because powder holding resin is weak and easy to wear because the holding power of the abrasive grains is weak, and in the case where liquid resin is used, there are almost no internal pores. There are drawbacks such as clogging and grinding burn. The latter problem becomes more prominent as the abrasive grains become finer. Therefore, when using superabrasive grains, particularly fine abrasive grains suitable for mirror finish, for resinoid grindstones, inorganic hollow bodies made of glass, ceramics, etc., organic hollow bodies made of acrylic resins, polyvinylidene chloride resins, etc., or By adding water-soluble particles such as chloride and sugar, it is possible to increase the strength of the abrasive layer or generate chips and pockets on the grinding surface to facilitate the discharge of chips and crushed abrasive particles. It has been broken.
JP-A-5-277756 U.S. Pat. No. 5,858,312 JP-A-11-156725 JP 2001-071275 A Special table 2003-500229 gazette

  However, if an inorganic hollow body or water-soluble particles having a higher elastic modulus than the resin binder is added to the grindstone structure, the grindstone structure is less likely to be elastically deformed. Is difficult, and the characteristics of the resinoid grindstone that can alleviate the load acting on the work material are hindered. On the other hand, when the organic hollow body is added, the grindstone structure is remarkably easily deformed elastically, so that the grinding surface is deformed by the reaction force acting from the work material during grinding, and the shape is maintained and extended. It becomes difficult to process the ground surface with high accuracy. That is, the conventional resinoid grindstone cannot achieve both dimensional accuracy and machined surface roughness using a general-purpose grinding machine.

  The present invention has been made against the background of the above circumstances, and an object thereof is to provide a resinoid grindstone that can be mirror-polished using a general-purpose grinder.

  In order to achieve such an object, the gist of the present invention is to have a grindstone portion in which superabrasive grains are bonded with a resin binder, and the surface of the grindstone portion by being rotated around a predetermined rotation axis. A resinoid grindstone of a type in which a material to be ground is mirror-ground with a grinding surface constituted by (a) an organic hollow dispersed in the grindstone portion having a characteristic that it is more easily elastically deformed than the resin binder. And (b) a support body that has a characteristic that is less elastically deformed than the resin binder and supports the grindstone portion from the back surface of the grinding surface.

  In this way, the organic hollow body that can be elastically deformed more easily than the resin binder is elastically compressed (ie, elastically deformed and functions as an air cushion) when a pressing force acts on the grinding surface. Therefore, the ground surface can be easily deformed. Therefore, if there are abrasive grains protruding on the grinding surface relative to other abrasive grains, the pressing force that the protruding abrasive grains receive from the work material during grinding is compared to other abrasive grains. Since it becomes large, the shrinkage amount of the organic hollow body located below the abrasive grains becomes relatively large, and as a result, the retreat amount of the abrasive grains on the grinding surface becomes larger than other abrasive grains. . Therefore, since grinding is performed in a state where the protruding heights of the abrasive grains from the ground surface are uniform, scratches on the surface to be ground are suppressed from being caused by the abrasive grains protruding largely locally. Mirror finish is possible even when used on a board. In addition, the organic hollow body exposed to the grinding surface and having a part of the outer peripheral wall cut off forms a chip pocket on the grinding surface, so that the crushed or dropped abrasive grains, grinding scraps of the work material, etc. Is housed in the chip pocket so that clogging is suitably suppressed. At this time, since the grindstone is supported from the back surface of the grinding surface by a support that is less elastically deformed than the resin binder, excessive deformation of the grinding surface is suppressed by the support, so the entire grinding surface Thus, the outer diameter dimension and shape accuracy can be maintained, and the surface to be ground can be processed with high dimensional accuracy and shape accuracy. As described above, mirror grinding can be performed using a general-purpose grinding machine.

  In addition, according to the present invention, since the organic hollow body is included as described above, the abrasive rate of the grindstone portion can be reduced, so that there is an advantage that dressing is easy while using superabrasive grains.

  Here, preferably, the organic hollow body has a modulus of elasticity that can be a value within a range of 2/3 to 1/4 of a modulus of elasticity when not including the modulus of elasticity of the grindstone when it is included. It is a thing. For example, preferably, the resin binder has an elastic modulus in a range of 1 to 5 (GPa), and the organic hollow body has an elastic modulus in a range of 0.1 to 1 (GPa). The support has an elastic modulus in the range of 5 to 200 (GPa). The organic hollow body preferably has an elastic modulus of about 1/30 to 1/2 times that of the resin binder, and the support has an elastic modulus of about 2 to 100 times that of the resin binder. Preferably there is.

  Preferably, the organic hollow body has a larger particle size than the superabrasive grains. In this way, the pressing force acting on the abrasive grains protruding to the grinding surface is transmitted to one organic hollow body, so that the grinding surface can be more easily deformed, and consequently the protruding height of the abrasive grains. Will be even more complete. More preferably, the organic hollow body has a particle size 3 to 10 times that of the superabrasive grains, for example, in the range of 50 to 150 (μm), more preferably an average particle size of about 100 (μm). It is what has.

  Preferably, the organic hollow body is composed of one kind or a mixture of two or more kinds of vinylidene chloride resin and acrylic resin.

  Preferably, the organic hollow body has an outer peripheral wall having a thickness dimension in a range of 0.1 to 5 (μm). In this way, since the outer peripheral wall is sufficiently thin, it is more easily deformed in the grindstone when a pressing force acts on the grinding surface.

  Preferably, the organic hollow body is contained in the grindstone part in a range of 10 to 30 (capacity part), more preferably about 20 (capacity part). In this way, since a large amount of the organic hollow body is included within a range in which the mechanical strength of the grindstone portion can be maintained sufficiently high, the pressing force acting on the abrasive grains exposed on the grinding surface is the organic matter. The possibility of being received by the hollow body is increased, and the protruding height is more easily aligned.

  Preferably, the superabrasive grains are fine particles having an average particle diameter by an electric resistance test method (hereinafter, the average particle diameter of the abrasive grains in the present application is a value by an electric resistance test method) of 20 (μm) or less. Abrasive grain. In this way, since extremely fine superabrasive grains are used, the protruding height is more easily aligned by the elastic deformation of the organic hollow body, and the pressing force is not applied from the work material. Initial variation in the protruding height is reduced. Therefore, scratches on the surface to be ground are less likely to occur, and a better mirror surface can be obtained. More preferably, the average particle size of the superabrasive grains is in the range of 3 to 15 (μm), and more preferably about 8 (μm) (corresponding to # 1500).

  Preferably, the superabrasive grains are contained in the grindstone portion within a range of 10 to 30 (capacity part), and more preferably about 20 (capacity part). When it is less than 10 (capacity part), the grinding performance becomes insufficient, and when it is more than 30 (capacity part), dressing becomes difficult.

  Preferably, the resin binder is contained in the grindstone part in a range of 30 to 50 (capacity part), more preferably about 40 (capacity part).

  Preferably, the resin binder is a thermosetting resin. More preferably, it is an epoxy resin, and bisphenol A type epoxy resin is particularly preferable.

  Preferably, the support is made of a vitrified grindstone or steel having abrasive grains bonded with a vitrified binder. In this way, these have a sufficiently high elastic modulus of about 50 (GPa) compared to the resin binder, that is, since it is difficult to elastically deform, the grindstone part in which the abrasive grains are bonded with the resin binder. Overall deformation is suitably suppressed. That is, the support can be composed of a resinoid grindstone having a relatively high elastic modulus using, for example, a resin binder such as phenol or epoxy, but a vitrified grindstone or steel is more preferred. The vitrified grindstone is preferably, for example, a highly bonded vitrified grindstone using aluminum oxide as abrasive grains, and the steel is preferably general carbon steel or cast iron.

  Preferably, the grindstone portion is provided with air holes having a diameter larger than that of the organic hollow body. In this way, when this air hole appears on the grinding surface, a chip pocket larger than the organic hollow body is formed, so that the discharge of crushed abrasive grains and chips becomes easier and clogging is further suppressed. .

  Preferably, the air holes may be formed of various materials selected from organic materials such as synthetic resins and inorganic materials such as ceramics, but preferably do not increase the elastic modulus of the grindstone, It is preferable to form by dispersing foamed polystyrene or the like having an expansion ratio of about 10 in the resin and heat-shrinking the resin, for example, when the grinding stone is aged.

  Preferably, the air hole has a diameter within a range of 3 to 100 times that of the organic hollow body, for example, within a range of 0.5 to 2 (mm), more preferably about 1 (mm). It is what you have.

  Preferably, the resinoid grindstone has a disc shape, a ring shape, or a cylindrical shape with an attachment hole through which the support body penetrates in the thickness direction in the center portion, and the grindstone portion on the outer peripheral surface thereof Are fixed with a uniform thickness. Such resinoid grindstones are used by being attached to general-purpose grinders such as surface grinders and centerless grinders, and do not require any special processing machine or dressing device for mirror finishing of work materials. is there.

  Preferably, the resinoid grindstone is a cup-shaped grindstone in which the support has a bottomed cylindrical shape, and the grindstone portion is fixed to an annular end surface on the open side. The present invention can be applied to various types of resinoid grinding wheels as long as they are rotary tools.

  Preferably, the resinoid grindstone is used for cylindrical grinding, surface grinding, internal grinding or the like.

  Preferably, the resinoid grindstone is used for through-feed or in-feed centerless grinding.

  Preferably, the grindstone portion is provided on the support in a thickness range of 2 to 10 (mm), for example, about 5 (mm). In this way, since the thickness dimension of the grindstone part is sufficiently thick, the organic hollow body is suitably compressed in the grindstone part so that the protruding grain height is uniform, while the thickness dimension of the grindstone part is sufficient. Therefore, it is preferable that the entire grinding wheel portion is compressed and deformed by the pressing force applied to the grinding surface, and that the outer peripheral surface shape is suitably prevented from being deformed, and is caused by thermal expansion of the grinding wheel portion. The reduction in dimensional accuracy is further suppressed. That is, since the resinoid grindstone of the present invention has a structure in which the grindstone portion is fixed to the support, even if the grindstone portion is bonded with abrasive grains by a resin binder having a large thermal expansion coefficient, Although the thermal expansion is suppressed by the support, there is an advantage that a reduction in dimensional accuracy due to the thermal expansion of the grindstone portion is suppressed, but this becomes more remarkable when the grindstone portion is thinned.

  Preferably, the grindstone portion includes abrasive grains having hardness lower than that of the superabrasive grains as an aggregate. Aggregates are preferably of the same particle size as superabrasive grains, for example, about # 1500, and should be included in a range of 5 to 20 (capacity part), preferably about 10 (capacity part). Is preferred. As the aggregate, artificial silicon carbide, alumina or the like is preferably used.

  Preferably, the grindstone portion is formed by casting a liquid mixture in which the superabrasive grains and the organic hollow body are dispersed in a liquid resin into a predetermined mold. In this way, since the grindstone portion is formed by curing the liquid resin while being filled between the abrasive grains and between the organic hollow bodies, the abrasive grains are compared with the case where the powder resin is used. The holding force is increased, excessive wear of the grinding surface is suppressed, and the wheel life is increased. In such a production method, the grindstone portion is formed into a dense body having almost no pores, but the organic hollow body (in the case where the organic material for forming the atmospheric pores is included, the organic material In addition, since the organic hollow body) functions as a pore forming material, problems such as clogging and burning due to the absence of pores in the grindstone portion do not occur.

  Further, in the case where the manufacturing method as described above is adopted, more preferably, the liquid mixture is poured into the outer peripheral side in a state where the support is disposed in the predetermined mold.

  Preferably, in the case where the casting molding method as described above is employed, the molding die is such that the inner surface into which the liquid resin is poured has releasability. In this way, when the liquid mixture poured into the mold is shrunk in the curing process, it is not fixed to the inner surface of the mold, so that the shrinkage is not hindered, so that distortion is suppressed. Further, it can be easily taken out from the mold after curing. Such a release treatment may be performed by, for example, forming the mold with a material having a mold release property such as polypropylene, coating the inner surface of the mold with a silicone resin or a fluorine resin, or forming a film such as a polypropylene resin. It can be performed by providing.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a perspective view showing an entire resinoid grindstone 10 according to an embodiment of the present invention. In FIG. 1, a resinoid grindstone 10 has a disk shape with an outer diameter of 305 (mm) × thickness of 20 (mm), and an inner diameter (hole diameter) of 127.6 penetrating in the axial direction (that is, thickness direction) at the center. The mounting hole 12 is about (mm), and includes a core part 14 having the mounting hole 12 and a grindstone part 16 fixed to the outer peripheral surface of the core part 14. In the present embodiment, the core portion 14 corresponds to a support.

  The core portion 14 is made of, for example, a resinoid grindstone having an outer diameter of about 295 (mm). This resinoid grindstone is formed by bonding abrasive grains such as aluminum oxide with a resin binder such as epoxy, and has a high elastic modulus of about 10 (GPa) as a whole. That is, it has a characteristic that it is relatively difficult to elastically deform.

  Further, the grinding wheel portion 16 is provided on the outer peripheral surface of the core portion 14 with a thickness dimension of, for example, about 5 (mm) in the radial direction. The grindstone 16 is formed by bonding abrasive grains (superabrasive grains) 18 such as diamond (preferably artificial single crystal diamond) having a grain size of about # 1500 with, for example, a bisphenol A epoxy resin binder 20. The abrasive grains 18 are fine abrasive grains having an average particle diameter of about 8 (μm), for example, and are present in the grindstone portion 16 in a substantially uniform dispersed state at a ratio of about 20 (capacity part). . The abrasive grains 18 are not limited to the above grain sizes, and those having various grain sizes can be used, and CBN abrasive grains may be used. In addition to the bisphenol A epoxy resin, the resin binder 20 may be a hard polyurethane resin or the like.

  FIG. 2 is an enlarged view showing the configuration of the grindstone 16, that is, the grindstone structure. The grindstone portion 16 is obtained by bonding abrasive grains 18 with a resin binder 20. In addition to these, for example, silicon carbide having a grain size of about # 1500, that is, about the same as the abrasive grains 18 (preferably artificial silicon carbide). An aggregate (not shown) made of general abrasive grains, etc., an organic hollow body 22 and the like are dispersed in the resin binder 20. In the grindstone structure, there are a large number of relatively large substantially spherical air holes 24. In the present embodiment, the pores of the grindstone portion 16 are also constituted by the organic hollow body 22 in addition to the air holes 24, and there are almost no voids in the other portions in the resin binder 20, so that the pores are dense. ing. The aggregate is included in the grindstone 16 at a ratio of about 10 (capacity part), for example. This aggregate is added to supplement the elastic modulus of the resin binder 20 to increase the elastic modulus of the grindstone 16, that is, to prevent elastic deformation. The elastic modulus of the remainder (hereinafter referred to as “resin structure” as appropriate) of the grindstone 16 excluding the abrasive grains 18, the organic hollow body 22, and the air holes 24 is about 3 (GPa), for example. That is, the above-described elastic modulus of the core portion 14 is about three times the elastic modulus of the resin structure, and has a characteristic that the elastic deformation is harder than that of the resin structure.

  The organic hollow body 22 is made of, for example, an organic compound such as any one of vinylidene chloride resin and acrylic resin, or a mixture of two or more thereof, and is about 100 (μm), that is, an abrasive. It has an average particle size about 12.5 times that of the grains 18 and is contained in the grindstone 16 in a substantially uniform dispersed state at a rate of about 20 (capacity part), for example. Since the organic hollow body 22 is a hollow sphere made of the resin as described above and having a thickness of the outer peripheral wall (shell) of, for example, about 0.5 (μm), the organic hollow body 22 is easily and elastically compressed when pressed. Can be. That is, the organic hollow body 22 is made of a material having a low elastic modulus of about 1/10 of the elastic modulus of the resin structure, and has a characteristic that it is more easily elastically deformed than the resin structure. For this reason, the elastic modulus of the grindstone 16 is lowered to a value in the range of about 2/3 to 1/4 when the organic hollow body 22 is not included.

  The air holes 24 are formed of a polymer organic compound such as expanded polystyrene having an expansion ratio of about 10 as described later, and have an average of about 1 (mm), for example, an organic hollow body. It has a diameter of about 10 times the particle size and exists in a substantially uniform dispersed state in the grinding wheel portion 16 at a rate of about 10 (capacity portion). The composition ratio of the resin binder 20 is the remainder obtained by removing the total volume of the abrasive grains 18, the aggregate, the organic hollow body 22, and the air holes 24 from the total volume. Part).

  The resinoid grindstone 10 configured as described above is used for, for example, centerless grinding as schematically shown in FIG. In FIG. 3, a shaft-like work (work material) 28 is placed on a work rest (blade) 26, and the work 28 is placed between the resinoid grindstone 10 and the adjustment wheel 30 arranged on both sides thereof. It is pinched. Then, the outer peripheral surface 32 of the workpiece 28 is ground by rotating the resinoid grindstone 10 at a predetermined rotation speed while rotating the workpiece 28 at a predetermined rotation speed by the adjusting wheel 30. The resinoid grindstone 10 and the adjustment wheel 30 are in a positional relationship in which the axes are slightly inclined from parallel to each other, but are simplified and drawn in parallel in the drawing.

  In the grinding process as described above, when the grinding surface 34 of the resinoid grindstone 10 is pressed against the outer peripheral surface 32 of the workpiece 28, as shown in FIG. The pressing force acting on the abrasive grains 18a and 18b protruding relatively large from the outer peripheral surface 32 becomes larger than the pressing force acting on the abrasive grains 18c having a relatively small protruding amount. In FIG. 4 described above, the grinding surface 34 and the workpiece outer peripheral surface 32 are simplified and drawn flat.

  At this time, in this embodiment, the binder of the grindstone portion 16 is composed of a low elastic modulus bisphenol A epoxy resin, and the organic hollow body having a lower elastic modulus than the resin binder 20 in the grindstone portion 16. Since 22 is dispersed, it is easily elastically deformed. Therefore, a large pressing force acting on the abrasive grains 18a and 18b is transmitted to the organic hollow body 22 via the resin binder 20, and this is elastically pressed. Shrink. That is, the organic hollow body 22 functions as an air cushion. Therefore, since the resin binder 20 is slightly elastically deformed in the vicinity of the grinding surface 34, the abrasive grains 18a and 18b are quickly retracted, and the tip of the cutting edge is shown in FIG. 4 (b). As shown, it is positioned on the same plane as the abrasive grains 18c. That is, the grinding process is performed in such a state that the protruding heights of the abrasive grains 18 are substantially uniform.

  Therefore, since the workpiece outer peripheral surface 32 is not ground with some abrasive grains 18 protruding excessively on the grinding surface 34, the occurrence of scratches by such abrasive grains 18 is suppressed, and as a result, # Fine processing with about 1500 fine abrasive grains is suitably realized. Thereby, although it is a general-purpose grinding machine such as a centerless grinding machine, an extremely smooth surface, for example, a mirror surface having a 10-point average roughness Rz of less than 0.5 (μm) (that is, smoother than that) can be easily obtained. For example, when the grindstone shown below is used under the following dressing conditions and grinding conditions, for example, in the 100th work material, a mirror surface with a 10-point average roughness Rz of about 0.11 (μm) with a processing time of about 5 seconds Could get. Conventionally, such a mirror surface could not be obtained unless barrel polishing or superfinishing was used. In addition, the work outer peripheral surface 32 could be machined with a high dimensional accuracy of about 2 (μm) or less in a range, for example.

[Whetstone]
・ Dimensions: φ420 × t150 × φ228.6 (mm)
・ Core part: φ405 × t150 × φ228.6 (mm), Vitrified whetstone core

[Dressing conditions]
・ Grinder: Centerless grinder ・ Grinding wheel peripheral speed: 2000 (m / min)
・ Dress cutting: R2 (μm / pass), Spark out 3pass
・ Dress lead: 0.06 (mm / rev.of.wheel)
-Dresser: Single stone dresser-Dress method: Wet dress

[Grinding conditions]
-Work material: SUJ2 fired material (HRc60), Pre-processing roughness: 0.4μmRz
・ Work material dimension: φ9 × L14 (mm)
・ Take allowance: φ5 (μm)
・ Grinding method: Wet through-feed centerless grinding ・ Wheel peripheral speed: 2000 (m / min)
・ Feed angle: 1.0 °
・ Correction angle: 0.5 °

  Moreover, when the air holes 24 existing in a dispersed manner in the grindstone 16 are exposed to the grinding surface 34, a huge recess 36 is formed in the grinding surface 34 as shown in FIG. The recess 36 functions as a chip pocket on the grinding surface 34, and temporarily discharges the abrasive grains 18 that have fallen off or are crushed from the grinding surface 34, swarf (that is, grinding scraps), and the like to discharge the recess. make it easier. Therefore, since clogging is suitably suppressed, there is an advantage that good sharpness is maintained for a long time, grinding burn is suppressed, and the workpiece outer peripheral surface 32 is ground more smoothly.

  Further, as described above, the grindstone portion 16 is configured to be easily elastically compressed and contracted, and thus the grinding surface 34 is configured to be easily elastically retracted. Is fixed to the outer peripheral surface of the core 14 having a higher elastic modulus than that of the resin binder 20 as described above (that is, less likely to be elastically deformed), so that excessive deformation of the grindstone portion 16 is suppressed by the core 14. The Therefore, since the grinding surface 34 is not excessively deformed, the dimensional accuracy and shape accuracy of the entire grinding surface 34 are maintained, so that there is an advantage that the workpiece outer peripheral surface 32 can be processed with high dimensional accuracy and shape accuracy. .

  Further, for example, 20 (capacity part) of artificial single crystal diamond abrasive grains (abrasive grains 18) having a grain size of about # 1500, and 10 (capacity part) of artificial silicon carbide (aggregate) having a grain size of about # 1500, as described above. 20 (capacity part) of the organic hollow body 22 having an average particle diameter of 100 (μm) and 10 (capacity part) of an expanded polystyrene resin having an average particle diameter of 1 (mm) for forming the air holes 24 (expanding ratio 10 times). ), Dressing and grinding were performed under the following conditions using a φ305 (mm) × t20 (mm) resinoid grindstone 10 produced with a bisphenol A-based epoxy resin binder 20 of 40 (capacity part). As a result, in the dressing process, no problem was found on both the grinding surface 34 and the dresser. Also, in the grinding process, 4 cut continuous grinding was performed, but when dressing with a single stone dresser, the 10-point average roughness Rz was 0.30 (μm), 0.30 (μm), 0.29 (μm), 0.32 An extremely smooth mirror-finished surface (μm) was stably obtained. Further, when dressing with a bond dresser, more excellent mirror finished surfaces of 0.19 (μm), 0.19 (μm), 0.20 (μm), and 0.19 (μm) were stably obtained.

[Dressing conditions]
・ Grinding machine: Cylindrical grinding machine ・ Wheel peripheral speed: 2000 (m / min)
・ Dress cutting: R2 (μm / pass) x 5pass (spark out 1pass)
・ Dress lead: 0.08 (mm / rev.of.wheel)
・ Dresser: Single stone diamond dresser, φ5 bond dresser # 200 Concentration 100
・ Dress method: Wet dress [grinding conditions]
-Work material: SUJ2 fired material (HRc60)
・ Work material dimensions: φ40 × t8
・ Grinding method: Wet plunge grinding ・ Work material peripheral speed: 25 (m / min) (3.4 rev / s)
-Cutting depth: φ10 (μm)
・ Cutting speed: φ1 (μm / s)
・ Grinding oil: Noritake Cool SEC-1500P (× 50)
・ Spark out: 12 (s)

  By the way, said resinoid grindstone 10 is manufactured as follows, for example. FIG. 5 is a process diagram for explaining a main part of the manufacturing process of the resinoid grindstone 10. In manufacturing the resinoid grindstone 10, first, in the blending step P1, the abrasive grains (diamond abrasive grains) 18, the aggregate (silicon carbide), the organic hollow body 22, and the air holes 24 are formed so as to have the ratio described above. The foamed polystyrene and the resin binder (liquid epoxy resin) 20 for forming were weighed and mixed sequentially in the mixing step P2. That is, first, the abrasive grains 18, the main component of the epoxy resin binder, the curing agent, and the organic hollow body 22 are mixed and stirred, for example, for about 10 minutes. Next, polystyrene foam is added to this and stirred for about 5 minutes. Next, in the pouring step P3, the liquid mixture thus obtained is poured into the mold 38.

  FIG. 6 is a schematic diagram for explaining an implementation state of the pouring step P3. In the figure, a mold 38 is provided with a recess 40 having an inner diameter of about 308 (mm) and a depth of about 22 (mm), for example. Is provided. In the recess 40, the core part 14 manufactured separately is arranged at the center part, and a gap 42 having an annular cross section with a radial width dimension of about 5 (mm) is provided between them. Is formed. As described above, the core portion 14 is made of, for example, a resinoid grindstone, and has a size of, for example, an outer diameter of about φ295 (mm) × t22 (mm). In the pouring step P3, the liquid mixture is poured into the gap 42 in the mold 38.

  Next, in the curing step P4, the resin binder 20 is cured by leaving it in the mold 38 at room temperature (that is, room temperature) for about 24 hours, for example, and then taking out (demolding) from the mold 38. For example, the main curing treatment is performed at a temperature of about 160 (° C.) for about 3 hours. In this process, the expanded polystyrene is shrunk and the air holes 24 are generated. Thereafter, the resinoid grindstone 10 is obtained by finishing the end face, the outer peripheral face (grinding face 34), the inner face of the hole (mounting hole 12), and the like.

  Since the resinoid grindstone 10 manufactured in this way is cast by using a liquid resin, the abrasive grains 18 are firmly held by the resin binder 20, so that excessive dropping of the abrasive grains 18 is suppressed. And a long life is obtained. There are no naturally occurring pores in the resin binder structure, but as described above, the air holes 24 are generated from expanded polystyrene, and the organic hollow body 22 forms pores functioning as chip pockets, so there is no problem. No.

  As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

It is a perspective view which shows the whole resinoid grindstone of this invention. It is a figure which expands and shows the grindstone part of the resinoid grindstone of FIG. It is a figure which shows typically the use condition of the resinoid grindstone of FIG. It is sectional drawing which expands and shows the principal part for demonstrating the change of the grinding surface in the use condition shown in FIG. 3, Comprising: (a) is a state in which the grinding surface is being pressed by the workpiece, (b) These are figures which respectively show the state by which the abrasive grain was pushed down according to the pressing force. It is process drawing explaining the principal part of the manufacturing method of the resinoid grindstone of FIG. (a), (b) is a figure explaining the pouring process in the manufacturing process of FIG.

Explanation of symbols

10: Resinoid grinding wheel, 14: Core part, 16: Grinding wheel part, 18: Abrasive grain, 20: Resin binder, 22: Organic hollow body, 32: Workpiece outer peripheral surface, 34: Grinding surface

Claims (4)

Resinoid of the type that has a grindstone part in which superabrasive grains are bonded with a resin binder and mirror-grinds the material to be ground with a grinding surface constituted by the surface of the grindstone part by being rotated around a predetermined rotation axis A whetstone,
An organic hollow body that has the property of being more easily elastically deformed than the resin binder and is dispersed in the grindstone part,
A resinoid grindstone for mirror grinding, comprising: a support body that has a characteristic that is less elastically deformed than the resin binder and supports the grindstone portion from the back surface of the grinding surface. The resinous grindstone for mirror-surface grinding according to claim 1, wherein the organic hollow body has a particle size larger than that of the superabrasive grains. 2. The resinoid grindstone for mirror-surface grinding according to claim 1, wherein the superabrasive grains are fine abrasive grains having an average particle diameter of 20 (μm) or less as measured by an electric resistance test method. 2. The mirror grinding resinoid according to claim 1, wherein the grindstone is formed by pouring a liquid mixture in which the superabrasive grains and the organic hollow body are dispersed in a liquid resin into a predetermined mold. Whetstone.

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