Study on the SUAM Double Magnet System for Polishing

Superconductive assisted machining (SUAM) is a novel machining method that eliminates tool interference via magnetic levitation tools. In our study, we developed a double magnet system (DMS) to increase the maximum power of the holding force and stabilize the magnetic rotation during polishing via the higher magnetic flux compared to a single magnet system (SMS). The maximum magnetic flux density of the DMS was approximately 100 mT higher than that of the SMS. In these cases, the entire holding force increases as the distance between the superconducting bulk and lower magnet decreases. The attractive forces are maximum around a displacement of 6 mm, although the repulsive and restoring forces increase spontaneously. The polishing performances of the DMS on the SUS304 and A1100P plates were evaluated using water-based diamond slurries, for equal levitation amounts. The amount removed by the DMS increased for the A1100P and SUS304 substrates compared to that by the SMS. In this case, we observe that the deviation of the polishing area on the DMS decreases compared to that of the SMS, reflecting a more stable rotation and movement due to the higher holding force.

Study on Polishing Method Using Magnetic Levitation Tool in Superconductive-Assisted Machining

Superconductive-assisted machining (SUAM) is a polishing method that employs a magnetic levitation tool, which is based on a superconductive phenomenon called the pinning effect. Since the tool magnetically levitates, the issue of tool interference is eliminated. In this study, in order to set up the polishing conditions of the magnetic levitation tool, we evaluated the relation between the flux density distribution relative to the tool position and the holding force acting on the magnetic levitation tool to maintain its initial position, set by field cooling by the superconducting bulk. For the holding force, we measured the attractive, repulsive, restoring, and driving forces. We found that the greater the holding force, the smaller the initial distance between the superconducting bulk and the magnetic levitation tool. The attractive force was found to peak when the levitated tool was displaced 6 mm from an initial position of 9 mm from the bulk, and it became only the self-weight of the magnetic levitation tool at displacements of 30 mm and above, where the pinning effect broke down. We then evaluated the polishing characteristics for SUS304 and A1100P at a tool displacement that results in the maximum attractive force. In the polishing experiment, we employed a water-based diamond slurry because the temperature of the workpiece was close to room temperature. We found that it was possible to polish SUS304 and A1100P while avoiding the effects of magnetization due to the polishing pressure or induced currents that accompany the rotation of the metal plate. The arithmetic average roughness, Ra, of A1100P was relatively high due to the effect of scratches, while that of SUS304 improved from 92 nm before polishing to 55 nm after polishing when polished with grains with a diameter of 1 μm.

Ultra-Precision Machining of Off-Axis Convex Ellipsoidal Surface Using Two Different Accurate Spiral Tool Paths

The off-axis parabolic mirror plays more and more important role in high-tech areas since the advantages of reducing space and improving the quality of imaging. Two ultra-precision manufacturing methods are often applied to machining the off-axis ellipsoidal mirror, which one is revolving the cylindrical blank around the axis of ellipsoidal surface and another one is revolving around the axis of cylindrical surface. But which machining method can produce a better result has no rounded comparisons and analysis according to previous research. In this paper, the tool path generation method is presented and the corresponding tool paths of each manufacturing method for the off-axis ellipsoidal mirror are calculated respectively. The motion characteristics are also analyzed and compared correspondingly. Finally, the effects of diamond tool parameters are further analyzed in theory to avoid the tool interference. The studies processed in this paper provide a theoretical basis of choosing the ultra-precision manufacturing method for the off-axis ellipsoidal mirror and can improve the efficiency and precision of processing.

Parameters Optimization for Roundness of Hemispherical Surface Milling

The hemispherical surface has been widely implicated in design of products. Its precise roundness, a key quality characteristic of smaller-the-better, highly depends on the milling quality of the hemispherical mold. In this paper, we study the optimal machining parameters for the roundness of the hemispherical mold processed by the five-axis NC milling machine with a rotatable-tilting table. Four machining parameters, tool’s tilt angle, surface-cutting speed, feeding per tooth, and depth in axial cutting, are considered with their three varied levels selected on the basis of the onsite professional knowledge acquired from weighing the effect of tool interference and the milling capability of machine tools. The material NAK80, one type of plastic mold steels, possessing excellent resistance and dimensional stability is used as experimental test specimens. The experimental results conclude that the optimal measurements of roundness for the concave and the convex hemispherical molds are 0.022 mm and 0.026 mm, respectively.

Development of CAPP/CAM System for Ultraprecision Micromachining - Process Planning Considering Setting Error

Ultraprecision machine tools can be expert power together with a CAD/CAM system in generating tool paths. However, CAM systems generally focus on generating NC data. Consequently, operators have to perform process planning by considering the features of machine tools, cutting tools and workpieces. Above all, the setting error may cause interference between the cutting tool and the workpiece, and result in low machining accuracy. Therefore, this study deals with the development of a CAPP/CAM system in ultra-precision micromachining to assist operators in relation to settings. The developed system determines the number of the used control axes of the machine tool, and calculates the required setting accuracy, while preventing tool interference and maintaining the shape error within the tolerance. From the simulation result, it is found that the CAPP/CAM system is effective in producing micro parts easily and accurately.

Rapid Toolpath Correction for Five-Axis High Efficiency Machining Based on Image Analysis

Five-axis high speed machining can improve the efficiency and accuracy obviously, but the machining errors and tool interference are likely to happen due to the complexity of tool motion. So the collision detection and verification of tool path are very important and necessary before machining the part. Using a combination of process simulation and collision detection based on image analysis, a rapid detection approach is developed in this research. The geometric model provides the cut geometry for the collision detection and records a dynamic geometric information for in-process workpiece. For the precise collision detection, a strategy of image analysis method is developed in order to make the approach efficient and maintian a high detection precision. An example of five-axis machining propeller is studied to demonstrate the proposed approach.

The Free-Form Surface Five-Axis Machining Global Interference Detection and Adjustment of Cutter Shaft

Proposed a construction method of visual cone, to solve the surface 5-axis NC machining tool interference problems with the surface. At any point on the surface structure the visual cone area, according to visual cone determine whether the global tool interference with surface, and correct the tool spindle of interference cutter, solved the global surface and tool interference problems successfully. The application shows, this method is of high efficiency, high precision.

Tool Interference Issues on ASME B31.3 Listed Flanges

In this paper, the authors investigate situations where flanges listed in ASME B31.3 may cause construction issues, due to interference between the assembly tools and the adjacent nuts. A variety of different tools that may be used for assembly have been considered. ASME B16.47 Series A and B, and AWWA C207 flanges have been evaluated, and tabulated into a series of charts to assist designers in avoiding problem flanges, or to identify situations where designers may need to consider modifying the bolting design to facilitate assembly. Changes between previous and current editions of AWWA C207, which may have exacerbated the problem have been identified, and evaluated, to assist owners and designers in issues that may arise with existing installed flanges, and to highlight several flanges which may have been used satisfactorily in the past, but may cause issues in new construction.