JP4846262B2 - Vitrified grinding wheel for glass ceramic surface finishing - Google Patents

Description

  The present invention relates to a vitrified grindstone for surface finishing of glass ceramics used for surface finishing such as mirror finishing of various glass ceramic parts in electronic, optical, optical communication, optical information, and the like, and a method for manufacturing the same.

  Glass ceramics, in which many fine crystals are precipitated in glass, is also called crystallized glass. It is hard, has a low coefficient of thermal expansion, withstands rapid heating and quenching, and is also an insulator or dielectric. It has become an important material in the field.

  In particular, glass ceramics in which alumina and a glass-based material are mixed is required for reducing the size and weight and increasing the functionality of electronic devices as dielectric sheets for IC substrates and multilayer ceramic chip components.

  In order to mirror-finish such glass ceramics by the action of abrasive grains, two types of methods, a free abrasive grain method and an abrasive grain fixing method, are known.

  In the loose abrasive system, polishing is performed with a resin polishing pad while supplying slurry-like cerium oxide abrasive grains to the processing surface. If a soft polishing pad made of resin is used at that time, this will deform along the processing surface, in other words, it will become `` familiar '', so especially the corner periphery etc. will be cut excessively and `` Who '' Often occurs. When a hard pad is used to avoid such a problem, scratches increase.

  Further, in the above method, there is a problem that a large amount of the free abrasive liquid generated during finishing affects environmental pollution, waste liquid treatment, economic efficiency, and the like during the processing.

  Because of these problems, the mirror surface finish of the so-called grindstone fixed method was put into practical use, but soft abrasives such as cerium oxide abrasives used in this method are unstable to heat and chemicals, and further to fine particles It was activated and the instability was promoted.

  In addition, cerium oxide frequently used as a glass abrasive is mixed with many other rare earth metal oxides as impurities, and the cerium oxide content in the total rare earth content is, for example, 40 to 60% of a normal commercial product. Therefore, in the abrasive grain fixed grindstone, impurities other than cerium oxide are also bonded and fixed simultaneously.

  Considering such physical properties of abrasive grains, vitrified for bonding abrasive grains is preferably one that can be bonded at as low a temperature as possible. Therefore, vitrified grinding stones for surface finishing of glass ceramics are at a lower temperature (about 200 ° C.) than inorganic vitrified bonds. Practical application by bondable organic synthetic resin bond has been promoted.

  As an organic synthetic resin bond grindstone, for example, instead of the free abrasive grain method in the mirror surface processing method, abrasive grains such as diamond, cerium oxide, and silicon oxide are mixed in porous fluororesin, and scratches do not occur. A grindstone for polishing a fluororesin bond that does not cause end face sagging on a processed surface is known (Patent Document 1).

  On the other hand, as an example of a vitrified grinding wheel bonded with a crystalline vitreous bond and an amorphous vitreous bond, an iron-based metal material is used for the purpose of producing a long-life, high-performance superabrasive (CBN, diamond) grinding wheel. It is known that abrasive grains are bonded with an amorphous bonded phase, and the crystalline phase is uniformly dispersed in 15 to 70% by volume of the bonded phase by firing (Patent Document 2).

  It is also known that the mixing ratio of non-crystalline glass and crystalline glass is 6: 4 to 8: 2 as a vitrified bond grindstone with good wetting with CBN abrasive grains and high bond strength and bending strength. (Patent Document 3).

JP 2003-53669 A Japanese Patent Laid-Open No. 9-225837 Japanese Patent Laid-Open No. 11-10546

  However, when the above-mentioned conventional organic resin bond grindstone is used to finish the entire shape, if high-hardness abrasive grains are used so as to maintain the pre-processing accuracy, scratches frequently occur on the glass finish surface. Also, if a porous or porous grindstone is used in that case, the finish flaws are reduced or eliminated, but the so-called grindstone becomes familiar with the machining surface due to deformation following the shape of the machining surface due to the elastic force of the grinding stone. This causes a problem that the shape accuracy is deteriorated.

  In addition, regarding surface properties, it is necessary to meet the demands of customers to obtain precise surface properties (surface roughness, defect-free (unscratched)) in response to higher performance and higher functionality of optics and electronic components. .

  In addition, as described above, the problem that the soft abrasive fixed grindstone deforms (adapts) following the work surface is solved, and at the same time, chemically and thermally unstable soft abrasive grains (cerium oxide, barium sulfate, etc.) ) Characteristics (soft mechanical action, high chemical reactivity), without any scratches or pit marks, and there was no knowledge to obtain a vitrified bond that can be fixed stably .

  In particular, in order to eliminate the influence of components that are not directly involved in the finishing action with respect to scratches, it is necessary to use a grindstone-fixed grindstone with a small amount of binder and high grindstone hardness, grindstone mechanical strength, and finishing performance. There is no vitrified bond that can do that.

  In addition, if abrasive grains are bonded using a glassy bond that is similar to the work piece of glass ceramics and is harder than soft abrasive grains, the abrasive wear is promoted. Clogging and clogging occur, and pits and scratches are likely to occur on the glass finish surface.

Other technical issues that should be further improved include the following.
1) Influence of glassy bond When glassy bond is used, which is the same quality as the work glass and is expected to be harder than soft abrasive grains, It seems.

a) Formation of porous and porous pores There was no knowledge for reliably obtaining a porous grindstone that was sufficiently porous so that there was no effect on the finished surface due to the inherent strength of the vitreous bond. In this case, the porous means a pore material having a pore size equal to or smaller than the primary pore diameter of the intrinsic pores or soft abrasive grains, and the porosity means that the artificial pore is formed by a pore material larger than the abrasive particle size. Say.

b) Exclusion of binders Select the type of bond that provides the wheel hardness and the wheel mechanical strength with a low binder ratio, based on the expectation that unfavorable results will occur if the binder is directly involved in the glass polishing finish. Must be adopted.

2) Problem of grinding wheel working surface It is necessary to maintain the clean grinding wheel working surface and improve the finishing effect by interposing the soft abrasive grains that have come off the grinding wheel between the porous hole vitrified bond grinding wheel and the glass ceramic surface of the work material. There is.

a) Type of vitrified bond Since the abrasive holding power (bond grip) is suitably weak and the bond band (bond bridge) is hard and rigid, it is necessary to select and adopt the type of bond.

b) Improvement of clogging Cluster-shaped soft abrasive grains that have fallen off the grinding wheel surface can roll between the grinding wheel and the machined surface, thereby suppressing clogging and clogging by the micro bearing effect (solid lubricant action). preferable.

3) Improvement with composite abrasive grains Two types of soft abrasive grains, mainly composed of the finish performance of soft abrasive grains rich in chemical reactivity, grinding wheel hardness utilizing the sinterability and diffusion reactivity of other abrasive grains, and By obtaining strength, clogging factors are reduced, enabling an ideal surface finish that is defect-free and a wide range of usable wheel performance.

[Wheel performance]
1) Grinding wheel life With regard to the abrasion of the bond type that has favorable characteristics for the surface properties, for the purpose of further strengthening the bond grip (abrasive holding power), by blending an appropriate amount of other bond types into a composite bond, Realizes a long-life wheel.

2) Certainty of the grinding wheel performance Various characteristics such as grinding wheel hardness, grinding wheel structure, and mechanical strength of the grinding wheel in order to satisfy the surface properties and ensure the grinding wheel performance for high accuracy, high efficiency and high economic efficiency. It is not easy to limit the value and adopt it selectively.

  Then, the subject of this invention solves the above-mentioned problem, and in soft abrasive grain fixed whetstone using a vitrified bond, chemically and thermally unstable soft abrasive grains (cerium oxide, barium sulfate, etc.) Soft abrasive grains are stably fixed without impairing properties (soft mechanical action, high chemical reactivity), and the surface of the glass ceramic is not scratched or scratched, and follows the machined surface. Thus, a vitrified grindstone for surface finishing of glass ceramics that enables precise finishing without deformation (unfamiliar).

  As a further problem, a glass with excellent softness and fixed grinding stones that has the required grinding stone hardness and the required mechanical strength, as well as high finishing performance. It is to make a vitrified grinding stone for ceramic surface finishing.

  In order to solve the above-mentioned problems, in the present invention, in a grindstone for glass ceramic surface finishing in which soft abrasive grains containing cerium oxide or soft abrasive grains containing barium sulfate in combination with cerium oxide are fixed by vitrified bonds A vitrified grindstone for surface finishing of glass ceramics, wherein the vitrified bond is a crystalline glassy bond having pores or a composite glassy bond in which an amorphous glassy bond is used in combination with the crystalline glassy bond; It was.

Cerium oxide (CeO ₂ , Mohs hardness 5) is generally used as a slurry abrasive for finish polishing of glass. In addition, the chemical reaction on the glass surface is suppressed, and the crystal phase in the glass and the glass In order to polish the matrix phase evenly and obtain a finished surface with higher smoothness, zirconium oxide (ZrO ₂ , 8-9) or magnesium oxide (MgO, 6) is used instead of cerium oxide with high chemical reactivity. May be applied.

In the present invention, barium sulfate (BaSO _4, 3-3.5) by using mixed as an auxiliary abrasive grains cerium oxide abrasive grains, thereby improving the finished surface of the glass ceramic stably.

  Barium sulfate has an average particle diameter of primary particles in the range of 1 to 10 μm and a purity of 98%. The thermal properties of barium sulfate begin to decompose at melting points 1580 ° C and 1200-1300 ° C. In addition, sintering is performed from about 600 to 700 ° C. by heating, and the particle system shrinks and becomes dense through the diffusion phenomenon of the surface, volume, and grain boundary. By utilizing such sintering characteristics of barium sulfate, it is possible to manufacture a fixed grindstone having a high degree of binding without increasing the binder.

  Moreover, in this invention, it is preferable to set it as the vitrified grindstone for glass-ceramic surface finishing which is a mixed abrasive grain which an abrasive grain consists of 40-85 volume% of cerium oxides, and 15-60 volume% of barium sulfate.

  By increasing the mixing ratio of barium sulfate without increasing the amount of binder, it becomes possible to increase the degree of bonding of the grindstone and at the same time increase the mechanical strength of the grindstone. In particular, the finished surface has no scratches and improves flatness, and the finish tends to decrease as the amount of barium sulfate increases and the amount of cerium oxide decreases.

  The mixing ratio of barium sulfate to cerium oxide is preferably 15 to 60%. If the mixing ratio of barium sulfate exceeds 60%, the amount of cutting decreases rapidly. On the other hand, when the mixing ratio of barium sulfate is less than 15%, the degree of bonding of the grindstone becomes soft, the wear amount of the grindstone increases, the finished surface becomes rough, and the effect becomes less preferred.

  In this invention, since the crystalline glassy bond causes a density change due to rapid shrinkage due to crystallization from the bond melt softened and flowed by firing, a high grindstone bond strength and strong grindstone mechanical strength can be obtained. The bond is highly viscous and has a large surface tension, and has a low fusing force on the abrasive grain surface.

  That is, in the present invention, soft abrasive grains (cerium oxide, 5) that are soft and have a Mohs hardness of about ½ or less compared to hard abrasive grains (for example, aluminum oxide, Mohs hardness of 12) are held stronger than necessary. This increases wear resistance and eliminates scratches.

  Furthermore, in the present invention, in order to ensure the elimination of scratches, the range of the types and physical properties of the soft abrasive grindstone using a crystalline glassy bond is limited in terms of hardness, structure and mechanical strength. It is preferable.

  The crystalline glassy bond can be used in the form of powdered glass, and may be a crystalline one in which fine crystals are precipitated from the melt that has been softened and fluidized by firing.

Crystalline powder glass, cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO 2), β -spodumene _{(Li 2 O · Al 2 O} 3 · 2SiO 2), eucryptite _{(Li 2 O · Al 2 O} 3 · 2SiO _2), Liu site _{(FeO · Al 2 O 3 ·} 4SiO 2), Jiobusaito _{(CaO · MgO · 2SiO 2)} , selected from Urumaito (2ZnO · 2SiO _2), β wollastonite _(SiO 2 · CaO), etc. it can.

  Next, the amorphous glassy bond used in the present invention will be described. Non-crystalline glassy bonds that only soften and flow through firing have a large adsorption effect on abrasive grains when the bond is highly viscous, lower surface tension, good wettability to abrasive grains, increase abrasive grain retention, The amount decreases.

  However, a crystalline glassy bond provides a hard bond and a strong grinding wheel mechanical strength with a small amount of binder, whereas an amorphous glassy bond requires a larger amount of binder. . Therefore, at the same degree of bonding, the binder ratio increases and the abrasive grain ratio decreases.As a result, in the amorphous glassy bond, there are many component layers that do not contribute to the polishing finish, the finishing efficiency decreases, and scratches occur. It becomes easy.

  For example, if a mechanically soft abrasive grain such as cerium oxide is held firmly, the abrasive wheel will eventually become clogged and clogged due to abrasive wear, resulting in the frequency of pit marks and scratches on the glass surface. Will increase.

  On the other hand, the crystalline vitreous bond has a loose abrasive holding force and a large amount of grinding wheel wear compared to the amorphous vitreous bond. As a result, fine cerium oxide abrasive grains fall off and wear repeatedly, rolling the surface of the grindstone and the work piece while microrolling, the grindstone is easily clogged and not clogged. This is the reason why the surface is not scratched.

  In this invention, a composite vitreous bond is applied as a grindstone wear countermeasure without impairing the lubricity (micro bearing effect) function of the crystalline vitreous bond.

  That is, in the present invention, the wear characteristics of the cerium oxide grindstone are improved by the composite vitreous bond in which 40 to 75% of the crystalline vitreous bond and 25 to 60% of the non-crystalline vitreous bond are mixed in the volume ratio of the powder glass. Make it a long-life wheel.

  The reason why the mixing ratio of the amorphous glassy bond is set to 25 to 60% is that if the amount is less than 25%, the effect of improving the grinding wheel wear amount decreases, and if it exceeds 60%, the wear amount becomes small. This is because crushing or clogging is likely to occur on the grindstone, and finishing scratches are generated.

The Mohs hardness of the soft abrasive grains in this invention is 5 for cerium oxide and 3-4 for barium sulfate.
Usually, the glass is said to have a Mohs hardness of 6 (midst of apatite 5 and crystal 7), but with a vitrified bond fixed whetstone using a glassy bond of the same type as the work glass, there is naturally a relationship with the finish flaw. Guessed.

  The present invention is a vitrified fixed grindstone made of porous glass using a crystalline vitreous bond with a small amount of binder and a high degree of grindstone bond strength and grindstone mechanical strength, and has a porosity of 45 to 60%. By using a porous or porous grindstone, for example, a bending strength of 250 MPa of borosilicate glass is set to a small bending strength of 5 to 35 MPa corresponding to about 2 to 15% of the bending strength. Solve the problem.

  Regarding the physical properties of the grindstone structure, in the present invention, the hardness of the cerium oxide grindstone using the crystalline vitreous bond is -60 to 60 on the Rockwell test method H scale.

The grindstone structure has a volume ratio of porosity of 45-60, an abrasive grain ratio of 35-45, and a binder ratio of 5-10.
The porosity decreases when it becomes harder than the RH hardness, and increases when it becomes soft. The decrease in the porosity causes the abrasive powder to be not easily discharged in a state where the grindstone and the workpiece are in surface contact, and causes scratching.

  In addition, an increase in the binder ratio and a decrease in the abrasive grain ratio are undesirable because the number of components not involved in the finishing action increases, resulting in a reduction in finishing efficiency and an increase in scratches.

  In the present invention, the RH hardness is −60 to 60, the porosity is 45 to 60%, the abrasive grain ratio is 35 to 45%, and the binder ratio is 5 to 10% within a range not exceeding 10%. When the binder ratio is less than 5%, the amount of wear of the grindstone is large, which causes a reduction in finishing efficiency and machined surface accuracy, and further causes scratching.

  With regard to the mechanical strength of the grindstone of the present invention, among various glass ceramic parts, in particular, the end surface spherical surface of the optical connector glass ferrule or the spherical surface finish of the SELFOC microlens surface, etc., and soft abrasive grains such as cerium oxide are used. It is the fixed whetstone used.

  At the time of overall shape finishing polishing, there must be no grinding wheel shape collapse in order to maintain the pre-processed shape accuracy. In other words, the grindstone must not elastically act on the workpiece corner to break the machining shape.

  Therefore, in this invention, instead of the elastic synthetic resin grindstone, a rigid inorganic vitrified grindstone is used.

  Furthermore, by clarifying the relationship between grinding wheel mechanical strength and grinding wheel finishing performance (cutting amount, grinding wheel wear, surface roughness, flatness, scratches), it is possible to further select the use of grinding wheels based on the grinding wheel structure for practical use. to be certain.

  Therefore, in this invention, a crystalline glassy bond or a composite bond of a crystalline glassy bond and an amorphous glassy bond is used, and the mechanical strength of a porous porous or porous cerium oxide grindstone is used for compression. The strength is 15 to 100 MPa, the bending strength is 5 to 35 MPa, and the elastic modulus is 2 to 12 GPa.

  This is because when the compressive strength is 15 MPa, the bending strength is 5 MPa, and the elastic modulus is less than 2 GPa, the amount of wear of the grinding wheel increases, and even when there is no scratch, the flatness becomes poor due to the grinding wheel shape collapse. Further, when the compressive strength is 100 MPa, the bending strength is 35 MPa, and the elastic modulus exceeds 12 GPa, the grindstone working surface is somewhat clogged, the machinability is deteriorated and the flatness is good, but scratches are seen.

  The vitrified grinding wheel for surface finishing of glass ceramics as described above is composed of soft abrasive grains containing cerium oxide, or soft abrasive grains containing barium sulfate in combination with cerium oxide, and crystalline glassy bond alone or crystalline glassy The main mixture containing the composite vitreous bond abrasive grains in which the bond and the amorphous vitreous bond are used in combination and the pore material are uniformly dispersed in a slurry state, then cast-molded, dehydrated and dried, and then formed, and thereafter 700- It can manufacture by baking at 900 degreeC.

  As described above, the vitrified bond is a glass ceramic surface finish that employs a vitreous crystalline vitreous bond or a composite vitreous bond in which an amorphous vitreous bond is used in combination with the crystalline vitreous bond. Because it is a vitrified grinding wheel, the soft abrasive grains can be stably fixed without damaging the soft and chemically reactive properties of soft abrasive grains such as chemically and thermally unstable cerium oxide and barium sulfate. There is an advantage that it becomes a vitrified grinding wheel for surface finishing of glass ceramics that does not cause scratches such as scratches or pit marks on the surface of glass ceramics, and enables precise finishing without following the processing surface and deforming. .

  Further, in the invention relating to the vitrified grinding wheel for glass ceramic surface finishing that employs a composite vitreous bond having a prescribed composition at a prescribed abrasive grain ratio, a soft abrasive fixed grinding stone is formed with a small amount of binder, and the required grinding wheel hardness Therefore, there is an advantage that a vitrified grinding wheel for surface finishing of glass ceramics is obtained which ensures the required mechanical strength of the grinding wheel and has excellent finishing performance.

  Further, by manufacturing the vitrified grindstone by firing a predetermined material at a predetermined temperature, there is an advantage that the vitrified grindstone for glass ceramic surface finishing having the above-described advantageous effects can be reliably and efficiently manufactured.

  The vitrified grinding wheel for surface finishing of the glass ceramics of the embodiment is obtained by firing and fixing soft abrasive grains containing cerium oxide, or soft abrasive grains containing barium sulfate in combination with cerium oxide, with vitrified bond, A crystalline glassy bond having pores or a composite glassy bond in which an amorphous glassy bond is used in combination with the crystalline glassy bond is employed. Below, each material is demonstrated, and also the manufacturing method and the evaluation method of the obtained grindstone are demonstrated.

(1) Soft abrasive grains 1) Polishing glass The cerium oxide (CeO ₂ , Mohs hardness 5) used in the present invention is a standard selected for glass polishing and has high chemical reactivity with glass. It is. The polishing mechanism by cerium oxide is expected to be due to the combined or synergistic effect of this chemical effect and the mechanical effect due to particle hardness.

  In addition, depending on the type of glass, especially with crystallized glass having excellent chemical resistance, the chemical effect of cerium oxide cannot be sufficiently exhibited. In hard glass, the mechanical effect is insufficient and the finishing efficiency is lowered, and in soft glass, surface defects such as pits and scratches are likely to occur.

Therefore, for example, in polishing finish of crystallized glass, soft abrasive grains having low chemical reactivity such as zirconium oxide (ZrO ₂ , 8-9), magnesium oxide (MgO, 5-6) are used instead of cerium oxide. Thus, by uniformly polishing the crystalline phase and the amorphous phase, a glass surface with excellent smoothness can be obtained.

However, when the hardness is higher than the work material such as zirconium oxide, defects such as pits and scratches are likely to occur on the glass surface. In that case, grinding wheel crushing and clogging are improved by mixing 15 to 60% by volume of barium sulfate (BaSO ₄ , 3 to 4) with respect to cerium oxide, and the glass surface accuracy is stabilized. It becomes possible. In this case, the reason for limiting the numerical value is that if the volume ratio of barium sulfate is less than 15%, the hardness and strength of the grindstone are not increased. This is because the effect is insufficient.

2) Cerium oxide The cerium oxide used in the present invention is mixed with many rare earth metals as impurities, and is chemically and thermally unstable. With cerium oxide, changes such as hue, sinterability, and weight loss are observed from around 700 to 800 ° C. by heating. Therefore, in the fixed grindstone of cerium oxide abrasive grains by vitrified bond, the grindstone firing temperature is 700 to 900 ° C, more preferably 750 to 850 ° C.

The particle size of cerium oxide used in the present invention is 0.5 μm in primary particle size, 45% purity, and a density of 6.2 g / cm ³ . The purity of cerium oxide is, for example, 40 to 60% of a commercially available product, and the particle size is preferably 0.5 to 3.0 μm. If the purity is less than 40%, the chemical effect is reduced, the number of particles that do not contribute to polishing increases, the finishing efficiency is reduced, and scratches are caused. When the particle size is less than 0.5 μm, the mechanical effect is lowered, and when the particle size exceeds 3.0 μm, the finishing efficiency is increased, but the finished surface is rough and easily scratched.

3) Barium sulfate Barium sulfate exhibits sinterability and weight loss at 600 to 700 ° C. or more by heating. The stable sinterability is 700 to 900 ° C, more preferably 750 to 850 ° C.
The barium sulfate particles used in the present invention have a primary particle diameter of 1.2 μm, a purity of 98%, and a density of 4.4 g / cm ³ .

  The grindstone firing temperature of the composite abrasive grains of cerium oxide and barium sulfate of the present invention is 700 to 900 ° C, more preferably 750 to 850 ° C.

(2) Vitrified bond A crystalline vitreous bond is a crystal grown and solidified in glass that has been softened and fluidized by firing. The composition system of the crystalline glassy bond is ZnO.B ₂ O ₃ .SiO ₂ .
On the other hand, the amorphous glassy bond has only a softening flow by firing. The amorphous glassy bond is a borosilicate system composed of SiO ₂ · B ₂ O ₃ · Al ₂ O ₃ · RO · R ₂ O. Both are used in powdered glass, refined to an economical particle size.

(3) Manufacturing method The volume of abrasive grains and bonds is weighed based on the respective density values, and the composite abrasive grains and bonds are mixed and mixed in a volume ratio (volume%).
Bonds, pores, temporary binders and other organic auxiliaries are formulated in a weight ratio to the unit abrasive grain amount. These mixed systems are made into a uniform dispersion system in a slurry state and then dehydrated and dried by casting. The obtained raw grindstone is fired after molding. The grinding stone firing temperature is fired at 700 to 900 ° C., preferably at 800 ° C.

(4) Grinding wheel evaluation method 1) Grinding wheel characteristic value a) RH hardness RH hardness in this invention is based on JISR6240, Rockwell type test method H scale, using 3.175mm steel ball for indenter, light test overload 196N, dedicated The measured value at the dial indication value is converted to RH hardness.

b) Grinding wheel structure According to JISR6240-1972, the porosity% is measured by an underwater immersion method. Further, the abrasive grain ratio% is determined from the grindstone density (g / cm ³ ). As a result, the binder rate% is also determined.

c) Grinding wheel mechanical strength The bending strength is measured by a three-point bending test in accordance with JISR1601. According to JISR1608, the compressive strength is a value obtained by compressing a prismatic sample having a constant size in the vertical direction and dividing the load at the time of fracture by the cross-sectional area perpendicular to the load direction. The elastic modulus is obtained by measuring the amount of deformation caused by the load in the bending strength test according to JIS R1602.

2) Actual cutting test a) Machining condition The machining mode is horizontal abscissa plane superfinishing where the wheel circumference is located at the center of the workpiece. Pre-processing is carried out with a surface roughness of 0.025 to 0.030 μmRa (centerline average roughness) using SD4000 mesh (abrasive grain size 3.0 μm), RH hardness 50, concentration 120, and vitrified grindstone.
The processing time is the finished surface roughness, and is 5 min where the steady state is assumed. The main processing conditions are shown in Table 1 below.

b) Types of grinding wheel performance The finishing amount (μm) and the grinding wheel wear amount (μm) are determined from the weight loss of the sample before and after processing. Each measured value is an average value of three samples.

  The finishing rate is a finishing amount (μm) per unit time (minute). In order to know the characteristics of the wheel performance, the finish ratio (finishing amount / whetstone wear amount) and the wheel wear ratio (whetstone wear amount / finishing amount) are obtained as reference values. For the finished surface roughness, the center line average roughness Ra (nm) is measured. Flatness is due to the measurement of surface waviness curves. Scratch scratches are observed with a stereomicroscope in detail from thin spot-like scratches to concentric notable scratches or pit-like scratches.

As described above, the advantages of the grindstone according to the embodiment are listed below.
(1) Crystalline glassy bond In this invention, soft abrasive grains such as cerium oxide used in polishing finishing of various glass ceramic parts are actively used for crystallization at high temperature during firing, and the amount of binder is small. It is a vitrified porous (porous) grindstone with fixed abrasive grains bonded with a crystalline glassy bond that provides high hardness and high strength.
On the other hand, due to crystallization at high temperature, the bond is highly viscous and has a large surface tension, the fusion force to the abrasive grain surface is reduced, and the abrasive grain holding force is loose. As a result, grinding stone clogging and crushing are suppressed by selecting an appropriate grinding wheel hardness or mechanical strength over a wide usable range, and a finished surface of several nanometers (Ra) or less without scratches can be obtained.

(2) Composite vitrified bond Grinding wheel wear by making a composite bond with an appropriate amount of non-crystalline vitreous bond that has excellent bond fluidity at firing temperature, a large bonding function with abrasive grains, and vitrifies during cooling The amount is reduced and improved (about 10%), and it can be a long-life grindstone with no scratches.

(3) Composite soft abrasive grains By mixing an appropriate amount of barium sulfate with cerium oxide to make composite abrasive grains, the RH hardness can be increased without increasing the binder (amount) ratio, and the fixed soft abrasive grains can be fixed free of finishing flaws. Vitrified grinding wheel becomes possible.

(4) Limited selection of characteristic values By selecting the characteristic values in terms of RH hardness, grinding wheel structure, grinding wheel mechanical strength, etc. in the horizontal axis surface polishing finish of borosilicate glass using soft abrasive grains such as cerium oxide In addition, it is possible to provide an abrasive-fixed vitrified bond grindstone with excellent surface roughness, no scratches such as scratches or pit marks, and high finishing performance and a wide usable range.

(5) Conclusion This invention is a soft abrasive grain using an organic synthetic resin bond in the present situation by wrapping and polishing method with soft loose abrasive grains such as cerium oxide of various glass ceramic parts such as electronic, optical, optical communication or optical information. This is an epoch-making invention that enables the practical use of a soft abrasive grain fixing grindstone using inorganic vitrified bond for practical examples of the immobilization grindstone.

(1) Examples 1 to 7 (Comparative Examples 1 to 8)
1) Grinding wheel characteristics Comparative Examples 1 to 8 for Examples 1 to 7 shown in Table 2 are shown in Table 3.
In Examples 1 to 7 and Comparative Examples 1 to 4, cerium oxide abrasive grains were bonded with a crystalline vitreous bond to form a fixed grindstone. For a soft grindstone with an RH hardness of less than 50, the same ratio is blended at a ratio of 0.1 binder amount to 1.0 unit abrasive grain amount, and the hardness is varied and adjusted by the pore material. That is, the amount of pore material was increased for the soft grinding wheel. In Examples 6 and 7 having an RH hardness of 50 or more, the amount of increase was 0.15 and 0.2 for the binder amount of 0.12 and Comparative Examples 3 and 4, respectively.

  Comparative Examples 5 to 8 are based on amorphous glassy bonds, and the amount of the binder is 0.12 (Comparative Example 5), 0.15 (6 and 7), and 0.17 (8), and many blending ratios. Needed.

  For example, as seen in the comparison between Comparative Examples 5 and 1, Comparative Example 6 and Example 1, or Comparative Example 7 and Example 4, the amorphous glassy bond is more crystalline than the crystalline glassy bond at the same RH hardness. Also required a large amount of binder. As a result, the grindstone structure had a high binder rate, but the grindstone mechanical strength was low.

  This is because the crystalline glassy bond is highly dense due to rapid shrinkage as it crystallizes from the amorphous bond melt at a high temperature during the firing process, and has a high grinding wheel hardness and machine even with a small amount of binder or a low binder ratio. It is because the strength is obtained.

2) Grinding wheel performance Examples 1 to 7 have a finishing rate (μm / min) of 1.45 or more in a range of RH hardness of −60 to 60, a finishing ratio of 2 to 3, and a grinding wheel wear ratio of 0.35 to 0.5. There were no scratches.

  Similarly, in Comparative Examples 1 to 4 using crystalline glassy bonds using cerium oxide abrasive grains, in the soft 1 and 2 having an RH hardness of −60 or less, the grinding wheel wear ratio is larger than 0.5, and thus the finishing rate is also large. The flatness deteriorated although there was no scratch.

  On the other hand, with a grinding wheel that is harder than RH hardness 60 (Comparative Examples 3 and 4), the finishing rate is less than 1.45 (μm / min), cutting is insufficient, the grinding wheel wear ratio is small, and the finishing ratio is large. The whetstone became clogged and scratches were slightly recognized.

  In Comparative Examples 5 to 8 using an amorphous glassy bond, even with a soft grinding stone having a negative RH hardness, the grinding wheel wear ratio is as small as less than 0.5, and therefore the finishing rate (μm / min) is less than 1.45. It was insufficient, and all of the whetstones were clogged or clogged.

(2) Examples 8 to 10 (Comparative Example 9)
1) Grinding wheel characteristics Examples 8 to 10 and Comparative Example 9 shown in Table 4 were blended at the same rate in a proportion of 0.12 binder amount per unit abrasive grain amount 1.0. In Table 4, the ratio of the amorphous glassy bond was changed to 4 types within a range of 25 to 80% by volume ratio. As the amorphous glassy bond increased and the crystalline glassy bond decreased, the RH hardness became soft and the mechanical strength of the grindstone also decreased.

  This is because the crystalline glassy bond crystallizes at a high temperature during the heating process and the volume change is large, whereas the amorphous glassy bond vitrifies at a low temperature during the cooling process and the volume change is small. is there. Therefore, in the phase state due to the mixed melting of crystalline and non-crystalline glassy bonds, the increase in the glass matrix phase with respect to the crystalline phase increases the bond fluidity and increases the abrasive adhesion, but the hardness and mechanical strength of the wheel Fell.

2) Grinding wheel performance As the amorphous glassy bond increased, the grinding wheel wear ratio increased and thus the finishing ratio decreased. When the amorphous glassy bond is 80% by volume (Comparative Example 9), the grinding wheel wear ratio is larger than 0.5, the finishing ratio is less than 2, and the finishing rate is less than 1.45 (μm / min). The surface is rough and flat. In addition, clogging peculiar to amorphous glassy bonds was observed, and scratches were recognized.

(3) Examples 11 to 15 (Comparative Example 10)
1) Grinding wheel characteristics In Table 5, composite abrasive grains of cerium oxide and barium sulfate were bonded with a crystalline vitreous bond.
The examples and comparative examples are blended at the same ratio of 0.1 binder amount to 1.0 unit abrasive grain amount. The grindstone firing temperature was set to 800 ° C. as in the other examples and comparative examples.

  In the abrasive mixing system, the heat diffusion phenomenon advances due to the increase of barium sulfate, and the RH hardness becomes hard due to the shrinkage and densification of the particle system. As a result, in the grindstone structure, the binder ratio, the grain ratio, and the grindstone mechanical strength also tended to increase.

2) Grinding wheel performance Although the RH hardness increased by mixing barium sulfate, the grinding wheel wear ratio increased and the finishing rate decreased due to the decrease in cerium oxide. Particularly when the mixing volume ratio of the abrasive grains is less than 40%, that is, when the cerium oxide abrasive grain ratio in the grindstone structure is about 15% or less, the finishing rate (μm / min) is about 1.0 or less. The surface roughness deteriorated at the same time. Characteristically, no scratches or pit marks were observed despite the increase in RH hardness and the decrease in finishing rate (μm / min) due to the mixing of barium sulfate. However, the flatness deteriorated due to an increase in the grinding wheel wear ratio.

Claims (6)

In a glass ceramic surface finishing grindstone in which soft abrasive grains containing cerium oxide or soft abrasive grains containing barium sulfate in combination with cerium oxide are uniformly dispersed and fixed in vitrified bonds,
The vitrified bond is Ri Oh crystalline glassy bond powder 40-75 body% and non-crystalline glassy bond powder 25 to 60 vol% of the composite glassy bond having pores, abrasive grains ratio of vitrified grinding stone 35 45 vol% and glass ceramics resurfacing vitrified wheels binder ratio and wherein 5-10 vol% der Rukoto.   The vitrified grindstone for glass ceramic surface finishing according to claim 1, wherein the abrasive grains are abrasive grains mixed with 40 to 85 vol% of cerium oxide and 15 to 60 vol% of barium sulfate. The vitrified grindstone for glass ceramic surface finishing according to claim 1 or 2, wherein the cerium oxide is cerium oxide having a particle diameter of 0.5 to 3.0 µm.   The vitrified grindstone for glass ceramic surface finishing according to any one of claims 1 to 3, wherein the vitrified grindstone is a vitrified grindstone having a porosity of 45 to 60% by volume. The glass according to any one of claims 1 to 4 , wherein the vitrified grindstone is a vitrified grindstone having an RH hardness of -60 to 60, a compressive strength of 15 to 100 MPa, a bending strength of 5 to 35 MPa, and an elastic modulus of 2 to 12 GPa according to the Rockwell test method. Vitrified grinding stone for ceramic surface finishing. Soft abrasive grains containing cerium oxide, or a soft abrasive grains containing a combination of barium sulfate with acid cerium, crystalline glassy bond powder 40-75 vol% and a non-crystalline glassy bond powder 25 to 60 vol% claims a composite glassy Bond, a mixture containing a pore material is uniform one dispersed in a slurry state, followed by casting, after dehydration and drying, and raw molding, wherein the firing thereafter 700 to 900 ° C. 2. A method for producing a vitrified whetstone for surface finishing of glass ceramics according to 1 .