Stereolithographies (SLs) using conventional methods lacks the ability to fabricate bulk multiple or mass parts simultaneously. In most cases. this is due to the fact that there is only one light source, e.g.a laser. Meanwhile, using multiple light sources for multipoint projection is expensive. In this experiment, we used a projector with a digital mirror device (DMD) and microlens arrays to simultaneously produce multiple micro-SL parts. We devised a multipoint fabrication method that employs mold image projection and microlens arrays. The object is fabricated on a controlled glass base that translates on X-Y table and translates on the Z-axis for lamination. We confirmed the formation of SL parts containing overhanging structures.
In the previous research, the ultra-smoothness grinding method based on the new concept is developed and applied to the horizontal surface grinder. From the results, the surface roughness is found to attain below 50nm (Rz) in grinding of a cemented carbide, a glass, ceramics and so on. The removal rate obtained using the horizontal surface grinder, however, is small though the rate is larger than lapping and polishing. First of all, in the research, in order to make the rate much larger, the rate in ultra-smoothness grinding method is analyzed. On the basis of the analysis, the vertical surface grinder is designed and manufactured on trial. Furthermore the grinding characteristics using the vertical surface grinder is examined. Comparing with the removal rate obtained using the horizontal surface grinder in the previous research, the removal rate attains 10 times in the same smoothness.
In this paper, a simple method for the measurement of thermal conductivity and absorption of laser beam in fine metal powder for rapid prototyping is proposed. When the heating time of the metal powder t is sufficiently short in comparison with the time until the metal powder reaches its maximum temperature T (t/T<0.1), and the measurement depth from a surface Z is longer than the diameter of the heat source a (Z/a>1.23), it is shown that the thermal conductivity of a metal powder can be precisely calculated by measuring the time that the temperature takes to reach its maximum value. As work materials, chromium molybdenum steel powder (SCM) and copper powder, whose diameters are 10μm, 20μm and 30μm, are used. As a result of measuring the thermal conductivity and the absorption of laser beam in various metal powders, the thermal conductivity of a metal powder is quite small compared with that of the metal, and the materials, the shapes and the diameter of a metal powder have little influence on thermal conductivity. The absorption at the surface of a metal powder is larger than that of the metal, and there is little difference among the materials.
Nowadays most of die and mold machining are manufactured by three dimensional controlled machining using ball end mill. Using this manufacturing method, we can obtain complex shapes by point contact machining between cutting tool and workpiece. To shorten set-up time and machining time, we have proposed 3+2 axis controlled machining method which the mold and dies are machined by indexing tilted tool axis on 5-axis machining center. In the proposed machining process, high speed machining is executed on each tilted tool axis. In this machining process, the list of indexing angle should be determined automatically, because the shape of the die and mold is very complex to determine the angle by an operator. Therefore, the main objective of this research is automatic determination method of the list of indexing angle for machining the die and mold. We have proposed, in the first and second reports, the calculation method of optimum indexing angle candidates for required machining surfaces using normal vectors of the surfaces and effective cutting edge shapes. And we have shown the procedure of deriving of optimum indexing angle and machinable area based on inverse offset method with state flag. However, we need the effective tilting angle range which we get the stable machining condition in tilted tool axis ball end milling. For this reason, in this research, we propose the machining experiment method using dynamic force dynamometer on 5-axis machining center to analyze the machining properties using tilted tool axis ball end cutting tool. And, we show the machining evaluation diagram from which the results of machining experiments property by tilted tool axis ball end cutting tool.
The in-process evaluation method of the working surface condition of grinding wheel is required to perform a grinding more easily and reasonably. In this paper, the method applicable to wet grinding was proposed for the in-process evaluation of the working surface condition. In addition, to clarify the effectiveness and validity, the complex change of the working surface condition during wet grinding of steel was evaluated with the proposed method. As a result, the following were clarified: By improving the response characteristics of the laser micrometer and by equipping the coolant removal device with compressed air, the working surface conditions can be evaluated during wet grinding. Moreover, it is possible to grasp the condition of working surface, where the complex change occurs, at any time during grinding. In addition, the change in the working surface condition can be evaluated quantitatively by measuring the peak distribution of the working surface at constant grinding intervals.
Carbon onion was oxidized by hydrogen peroxide to modify its tribological properties. The microstructure of carbon onion oxidized was characterized with electron high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and thermo gravimetric analysis. HRTEM and Raman studies showed that internal constitution of the carbon onions hardly change. Thermo gravimetric analysis showed that oxidation reduced the combustion temperature of carbon onion. Solid lubricant properties of the carbon onion oxidized were measured by ball-on-disk type friction testing using silicon wafers and steel balls in air, vacuum and dry nitrogen. By oxidation, friction coefficient of carbon onion became slightly higher and the lubrication life became longer, especially in vacuum. These results suggested that surface defects of carbon onion increase and its surface becomes active.
The most important problem in the micro drilling of ductile materials such as steels is a tool breakage due to poor tool rigidity and chip removal. The cavitation, which is generated by ultrasonic vibration applied on machining fluid, accelerates the chip removal. This paper deals with thrust force, tool life, chip geometry etc. for various drilling conditions in drilling SUS304 with (Ti, Al) N coated tool with a diameter of 0.1mm. In addition, the effects of pre-drilling using a center drill on tool life and of G73 cord on the machining efficiency are investigated. The obtained results are as follows. The thrust force hardly varies with feed speed and increases with step feed. The micro drilling assisted with cavitation achieves very longer tool life compared to the conventional drilling. Furthermore, the quick bite leads to longer tool life. The smaller feed speed and the larger step feed, respectively, bring out the shorter tool life.
An integrated machine tool is a type of multi-axes machine tools that has capabilities of both milling and turning. This paper presents a method to measure the dynamic angular motion accuracy of a rotation axis (B-axis) of a milling spindle under the synchronous motion by the B axis and linear axes. The present scheme identifies dynamic motion errors at the tool tip in radial and tangential directions by using the combination of ball bar measurements. The effect of setup errors is discussed in details. As case studies, the present scheme is applied to two different integrated machine tools, the one with a B-axis driven via a worm gear, and the other with a B-axis driven by a direct drive motor. The dynamic motion error is evaluated and its error sources are diagnosed on each machine.
Since a manufacturing feature, in computer aided process planning (CAPP), is the medium of information communication in the data sharing between design and manufacturing, i.e. CAD and CAM, it has an important role to complete optimum process planning in its correct capture and communication capability. For the purpose of improving this communication, an approach of using a feature dependency of manufacturing feature based on a base plane was proposed and verified for smooth integration between CAD, CAPP and CAM in the previous paper. According to successive trial and usage by real machining parts in some industries, it becomes clear that a certain feature such as a chamfer element causes effects of annoyance for other feature recognition, and multiple feature definition for a single feature is required under interactions by the others. To solve these requirements for applying more sophisticated parts, filtering method for undesired features to complete correct feature recognition and multiple feature definitions for features in interactions are proposed in this paper. Finally the representation schema of feature dependency including these results is proposed, and the approach is verified by a developed prototype SCAPP system.
This paper proposes a new method for constructing CAD data from 3D sensed data for the purpose of realizing reverse engineering. In CAD data of many industrial products, geometrical features such as flat planes and cylinders are defined on the boundary surfaces. In the proposed method flat planes, cylinders and cones can be extracted robustly from the complicated geometry or high noisy sensed and CAD data that contains the features can be constructed. The robust feature extraction is done through the following approaches: (1) Estimating geometric parameters of the features using the Gaussian image: and (2) Extracting the features by using “growing surface method”. The method has been applied to some 3D sensed data and the validity of the method was confirmed.
Lure fishing and fly-fishing have been positioned as sports deliberately different from the traditional Japanese fishing-style. In the case of fly-fishing, casting is the element which anglers must master in order to cast a fly, done so by using the weight of a line. This study uses experimental and computational analysis to investigate the dynamic behavior of a fly line. Fly-fishing constitutes various elements, but the importance that casting holds is extremely large. Fling speed, the casting process and the loop shape of the line while in flight are important for the proper presentation of flies. Moreover, the shape of a fly line is also important for a long cast or controlled cast. However, it is difficult to grasp the phenomenon or to make a numerical model because a fly line is an object of flexible string. Therefore, the most suitable casting method will be clarified from the viewpoint of sports engineering and human dynamics. In addition, measuring an angler performing movements with a flexible object such as a rod or a line is difficult. So establishing a method to measure the dynamic behavior precisely is also one of the purposes of this study. The rebound phenomenon occurs in the casting process. In this study, the casting experiment by a human and a machine were proceeded. The dynamic model of a rod and a line was made using multibody dynamics. It became clear that the vibration of a rod reduced by a rebound phenomenon.
Recently, linear motors have become popular as a feed drive in NC machine tools to achieve higher speed and higher accuracy. However, many problems were remained in linear motor drives. One of them is a problem related with the tandem drive. Due to its smaller force capability, plural linear motors are often used in parallel to drive an axis simultaneously. This paper presents how to achieve higher gain in the position-tandem control by preventing mutual axis interference through feedback control of properly treated velocity signals from two feedback drives. By using the proposed compensation methods, the servo stability is remarkably improved.
Recently, it is difficult to design a fully rigid base-frame within the limited weight restriction. The aim of this paper is to propose a method of compensation for the stage position measurement error occurred by the elastic deformation in the base frame. First, it is shown with analysis and simulation, that the method improves the stage positioning accuracy. Next, it is shown with experiment that the standard deviation of the stage repeatability if improved from 9.4nm to 4.5nm. It shows also that this method is effective in making semiconductor lithography equipments lightweight.