Resinoid Bonded Diamond Wheel Research Articles

強誘電体単結晶PMN-PTの超精密平面研削と幾何学的表面評価

Thin plates of lead magnesium niobate-lead titanate (PMN-PT) single crystal were ground with various cup-type resinoid-bonded diamond wheels on an ultra-precision surface grinder to obtain super smooth surfaces. The ground surfaces and sub-surfaces were observed with various instruments, such as laser microscope and atomic force microscope. The grinding modes such as ductile, ductile & fracture, and fracture modes are affected by grinding conditions. The relationship between finished surface roughness and grinding conditions was clarified experimentally. Very smooth surface less than 1nm Ra without micro-crack was obtained by ultra-precision one pass grinding. Compared with polishing, very sharp edges were also obtained by ultra-precision grinding.

High Precision Grinding of Large Fresnel Lens Mold

Demand for glass Fresnel lenses is increasing in solar panel manufacture in order to increase power efficiency. Glass lenses are usually moulded using a glass moulding method with tungsten carbide moulds. In this study, large Fresnel lens moulds made of tungsten carbide are tested to be ground by a simultaneous 2-axis (Y, Z) controlled grinding method. The resinoid bonded diamond wheel is trued with a rare metal truer to increase the sharpness of the wheel edge. In the grinding test of the tungsten carbide mould, a form accuracy of less than 0.8 μm P-V and surface roughness of 18 nm Rz are obtained, and it is clarified that the proposed grinding method is useful for Fresnel grinding.

Precision Grinding of Structured Tungsten Carbide Mold

Demands of glass Fresnel lens is increasing in solar panel in order to increase power efficiency. Glass lens is usually molded by glass molding method with tungsten carbide molds. In this study, large Fresnel lens molds made of tungsten carbide are tested to be ground by simultaneous 2-axis (Y, Z) controlled grinding method. The resinoid bonded diamond wheel was trued with a rare metal truer to improve the sharpness of the wheel edge. In the grinding test of the tungsten carbide mold, a form accuracy of less than 0.8 μm P-V and surface roughness of 18 nm Rz were obtained, and it is clarified that the proposed grinding method is useful for the Fresnel grinding.

Ultra-precision surface grinding of PMN-PT relaxor-based ferroelectric single crystals

Lead magnesium niobate-lead titanate (PMN-PT) single crystals with high piezoelectric coefficients, extremely large piezoelectric strains and very high electromechanical coupling factors are expected to be used in various new sensors and actuators of high performance, instead of lead zirconate titanate (PZT). PMN-PT (0 0 1) planes were ground with various resinoid-bonded diamond wheels in order to obtain thin plates. The features of the ground surfaces change with crystallographic orientation and machining conditions. A surface roughness of 0.44 nm Ra was obtained under adequate grinding conditions. Thin PMN-PT crystals of less than 10 μm thickness were obtained by this grinding process.

Study on Precision Machining of Glass Lens Mold with Minute Structures (2nd Report)

In recent years, the demand of optical devices with complicated and highly accurate shape such as Fresnel lens and f-q lens is growing up in terms of miniaturization and improvement of information equipments. Moreover, the demand of glass lenses increases for the purpose of improving its heat resistance and optical performances. The study proposes a machining process for non-axisymmetric aspheric cemented tungsten carbide mold with minute structures, aiming at high precision machining. In the proposed process, the non-axisymmetric aspheric surfaces except for minute structures are at first machined by the spiral form grinding tool path with a spherical resinoid bonded diamond wheel. The machined surface center is corresponding to the center of the rotation axis of ultraprecision machine tool. Afterwards, the surfaces are ground for compensation, based on allover shape measurement interpolated by cubic spline. Then, minute structures are created on non-axisymmetric aspheric surfaces by the grinding with a disk type metal bonded diamond wheel. As a result, it is found that the proposed machining method has the potential of producing a high precision non-axisymmetric aspheric glass lens mold with minute structures effectively.

C07 超音波振動子用圧電単結晶の超精密研削(OS11 超精密加工(2))

The lead magnesium niobate-led titanate (PMN-PT) piezoelectric single crystals were ground by a ultra-precision surface grinder with various cup-type resinoid-bonded diamond wheels under a wide range of grinding conditions in order to obtain thin plates for ultrasonic transducers. As a result, thin PMN-PT crystal samples of 4μm thickness were obtained by this grinding process.

S1302-2-4 SiCウエハの超精密研削加工技術の開発(超精密加工(2))

Silicon Carbide (SiC) have attracted increasing attention as one of materials for next-generation power devices. However, there are difficulties in high-efficient and ultra-precision grinding of SiC materials due to hard and brittle characteristics. We investigated appropriate surface grinding condition of 4H-SiC wafers by using ultra-fine diamond wheels. In this paper, we realized some effects of the kind of grinding wheel and wheel speed by measuring grinding force, flatness and roughness on work. By using vitrified bonded diamond wheel SD2000V for rough grinding and resinoid bonded diamond wheel SD5000B for finish grinding, the accuracy of work surface has reached PV = 0.56μm in flatness and Rz = 20.2 nm in roughness.

Precision grinding of microarray lens molding die with 4-axes controlled microwheel

This paper deals with precision grinding of microarray lens (fly eye) molding die by using a resinoid bonded diamond wheel. An ultra-precision grinding system of microarray lens molding die and new truing method of resinoid bonded diamond wheel were developed. In this system, a grinding wheel was four-dimensionally controlled with 1 nm resolution by linear scale feedback system and scanned on the workpiece surface. New truing method by using a vanadium alloy tool was developed and its performance was obtained with high preciseness and low wheel wear. Finally, the microarray lens molding dies of fine grain tungsten carbide (WC) was tested with the resinoid bonded diamond wheel to evaluate grinding performance.

A wavelet-based methodology for grinding wheel condition monitoring

Grinding wheel surface condition changes as more material is removed. This paper presents a wavelet-based methodology for grinding wheel condition monitoring based on acoustic emission (AE) signals. Grinding experiments in creep feed mode were conducted to grind alumina specimens with a resinoid-bonded diamond wheel using two different conditions. During the experiments, AE signals were collected when the wheel was ‘sharp’ and when the wheel was ‘dull’. Discriminant features were then extracted from each raw AE signal segment using the discrete wavelet decomposition procedure. An adaptive genetic clustering algorithm was finally applied to the extracted features in order to distinguish different states of grinding wheel condition. The test results indicate that the proposed methodology can achieve 97% clustering accuracy for the high material removal rate condition, 86.7% for the low material removal rate condition, and 76.7% for the combined grinding conditions if the base wavelet, the decomposition level, and the GA parameters are properly selected.

218 PCDフライス工具による超硬製マイクロ非球面金型の超精密切削に関する研究(OS-6 超精密加工)

Molding dies of hard and brittle materials such as hardened steels or WC were usually ground by resinoid bonded diamond wheel. Recently, cutting process needs to be short and easy by applying diamond cutting. In this study, a new micro milling tool of PCD was developed and basic cutting characteristics were researched in milling of WC. And a feasibility study of a precision fresnel cutting was carried out. From the experimental results, mirror surface and sharp edge were obtained. It is clarified that precision cutting of WC dies can be done with the developed PCD milling tool.

マイクロ非球面研削に関する研究 : クロス方式の斜軸研削における研削点固定制御方式の提案とその精度評価(S58 研削加工と砥粒加工,S58 研削加工と砥粒加工)

This paper deals with a precision grinding of micro axis-symmetric aspherical surface by use of a resinoid bonded diamond wheel. Ultra-precision grinding system of axis-symmetric aspherical surface was developed. In this study, a grinding point fixation control method on 45 degrees diagonal axis grinding method was proposed and its form deviation was evaluated. In this system, a resinoid bonded diamond wheel was scanned on the workpiece surface 3-dimentionally controlled with Inm resolution by linear scale feedback system.

101 Precision Grinding of None-Axis-Symmetric Aspherical Surface

This paper deals with a precision grinding of none-axis-symmetric aspherical surface by use of a resinoid bonded diamond wheel. Ultra-precision grinding system of none-axis-symmetric aspherical surface was developed. In this system, a resinoid bonded diamond wheel was 3-dimentionally controlled with 1nm resolution by linear scale feedback system and scanned on the workpiece surface. At first, the effects of the wheel errors on the workpiece form accuracies and surface roughness were simulated and its compensation methods were discussed. Secondly, the effect of wheel scanning direction on the workpiece surface roughness was researched experimentally. Finally, the none-axis-symmetric aspherical molding dies of a fine grain tungsten carbide were tested with a resinoid bonded diamond wheel to evaluate grinding performance.

313 軟鋼研削法ツルーイングにおけるメカニズムの検討(G.S.3-3 生産加工・工作機械I)

On the grinding of a fine ceramic,both trueing and dressing processes are important. Because the resultant of their processes have directly influences upon the finishing surface-grade. The method of grinding of a mild steel is often applied to trueing of resinoid bonded diamond wheel due to simplicity. In this study,experiments were carried out to certify the mechanism of griding of several mild pieces with three different types of resinoid bonds,such as BG.BF and BE.The noteworthy phenomena are appeared as a result.

SYSTEMS APPROACH FOR THE CERAMIC THRU-FEED CENTERLESS GRINDING

ABSTRACT An approach for simulation and production implementation of thru-feed centerless grinding of transformation toughened zirconia using vitreous bond diamond grinding wheels is presented. A set of grinding tests was designed and conducted to identify the effects of abrasive product (diamond grit size), work-material, and operational factors (stock removal, thru-feed rate, number of thru-feed passes and truing and dressing methods) on grinding performance. Evaluation parameters of surface finish, grinding forces and C-ratio were utilized to determine machine tool features. Very fine surface finishes, in the order of 0.05 to 0.1 u.m Ra range, could be achieved using vitreous bond micro-grit diamond wheels, without additional part processing. Such a level of surface finish on ground ceramics has traditionally been generated only by using resinoid bonded diamond wheels. These test results were used to design and manufacture a full-size composite or sandwiched diamond grinding wheel. This grinding wheel has been successfully applied in high-volume ceramic production, which in turn has verified the proposed approach. Lastly, the surface finish data is interpreted based on SEM and AFM observations and materials properties.

画像解析による砥石作業面の評価 （第２報） 研削過程における砥石作業面変化の追跡測定

This study deals with the post-process measurement of the grinding wheel topography by means of a newly improved image processing system. In this system, grinding wheel is driven by the high-power electric servomotor with a built-in rotary encoder so that both grinding operation and consecutive measurement of the individual abrasive grains by the accurate wheel positioning are possible. The contraction/expansion process is useful for the separation of adjacent grains. The dark field microscopy is effective in order to extract monochromatic CBN grains from the lustrous metal bond. This system is applicable to the practical grinding operation with resinoid and metal bonded superabrasive wheels with a good degree of accuracy and efficiency. In grinding normally sintered silicon nitride with the resinoid-bonded diamond wheel at a given grinding condi-tion, this system reveals that cutting-edge ratio decreases rapidly due to the micro-fracture of grain tips at the transient stage just after truing/dressing, and it increases slightly with the promotion of attritious wear under the successive steady state. This phenomena are explained by the fact that abrasive grains are damaged during truing/dressing operation.

Ultraprecision Surface Grinding of Chemical Vapor Deposited Silicon Carbide for X-Ray Mirrors Using Resinoid-Bonded Diamond Wheels

Chemical Vapor Deposited Silicon Carbide (CVD-SiC) on sintered silicon carbide has been ground by the ultraprecision surface grinder having a glass-ceramic spindle of extremely-low thermal expansion with various cup-type resinoid-bonded diamond wheels for getting high-brightness synchrotron radiation mirrors. The surface roughness depends upon the average grain size of a wheel, feed per wheel revolution and degree of cutting edge wear. A very smooth surface of 0.266nm rms was obtained by ultraprecision grinding without polishing. A high specular reflectivity of 88.7% at 0.834nm in wavelength was obtained on the ground surface at the grazing incident angle of 0.7–0.95 degree, parallel to the grinding direction.

超精密平面研削による無機非線形光学結晶ＫＤＰの光学面創成

Potassium dihydrogen phosphate (KH2PO4) called KDP was ground by an ultraprecision surface grinder having a glass-ceramic spindle. of extremely-low thermal expansion with various cup-type resinoid-bonded diamond wheels under various grinding fluids. Grinding fluid is a key factor of performing ultraprecision grinding of KDP crystal, because the crystal is extremely deliquescent. The grinding modes such as ductile, ductile & fracture, and fracture modes are affected by the grinding speed, depth of cut, feed per wheel revolution, average grain size of diamond wheels. The surface roughness depends upon the grinding direction, grain size, feed per wheel revolution, viscosity of silicone oil and kind of alcohol as an additive. The optical surface of 0.553nm rms, 3.40nm Ry in surface roughness, measured with TOPO-2D, 40×has been obtained by using SD5000-75-B diamond wheel after grinding of LHG-8 laser glass with a mixture of 10cSt silicone oil and 5wt% heptanol as grinding fluid.

Semi-ductile grinding and polishing of Pyrex glass

Semi-ductile grinding followed by simple mechanical polishing is an economical process for producing a mirror-like surface for hard and brittle Pyrex. A fine-grit resinoid-bonded diamond wheel was used to generate large amounts of ductile streaking to improve the surface quality and reduce the polishing time. The ground samples were polished with diamonds and/or cerium oxide to analyse the effect of the abrasives, the polishing pad and the pressure on the surface produced. The microstructure of the ground sample was investigated using a scanning electron microscope whilst the polished surface was analysed using an atomic force microscope. The results of this study show that: (i) as much as 85% of ductile streaks were found on the ground surface; and (ii) the cerium oxide polishing process yields the best surface, the latter having a roughness of 8.7 nm after 2 min of polishing, with very few fine hair-line scratches.

マイクロ非球面の超精密研削に関する研究 斜軸研削法によるマイクロ非球面の鏡面研削の可能性検証

This paper deals with the grinding of the micro aspherical surfaces. A new grinding method and a grinding system with the inclined rotational axis of micro grinding wheel were developed. The grinding wheel axis is 45 degrees inclined from the workpiece rotational axis. The micro wheel was resinoid bonded diamond wheel of #1200 in the grain size. The wheel was formed to a precise columnar shape of 0.8 mm in the diameter by a single crystal diamond truer on the machine. The grinding spindle is equipped with an air bearing and the maximum rotational rate is 10 × 104 rpm. In the grinding test, WC (tungsten carbide) of the glass molding die was tested. The primary grinding workpiece was measured for the distributions of the form deviation profiles to evaluate the deviations of the tool positioning and the tool radius. The NC-program was then edited to compensate reproducible errors. By the developed system, the form accuracy of about 0.1 μ m P-V and the surface roughness of less than 0.03 μ m Rmax were obtained.

Surface Roughness Generation Mechanism of Ultraprecision Grinding of Optical Materials with a Cup-Type Resinoid-Bonded Diamond Wheel

Super-smooth optical glass surfaces have been obtained by grinding using an ultraprecision surface grinder and a cup-type resinoid-bonded diamond wheel without any polishing. This paper deals with some mechanisms of surface roughness generation for brittle materials in ductile mode grinding. The shape of the contact area between a cup-type diamond wheel and sample in ultraprecision grinding has been measured with an optical profiler. The shape is affected by the grain size of the diamond powder, feed rate, and grinding time. Surface roughness can be estimated by a simple surface generation model where the inner edge angles of the wheel and feed rate determine the surface roughness in the ductile mode. The inner edge angles are affected by various grinding conditions.