It is important in surface machining to estimate tool wear because it has a large effect on precision and surface roughness of a workpiece. In this study, tool wear of a ball end mill is investigated in order to design an effective estimator of the wear. Wear distribution of the tip is calculated based on the geometric model of the tool and milling parameters measured in preparatory experiments under some limited cutting conditions. The proposed algorithm of wear estimation is tailored to cutting of a plane and a curved surface. The algorithm is applied to compensate processing error due to tool wear in the case of milling of the curved surface of S55C, resulting effective reduction of the processing depth error compared with no compensation.
In the 1st part of this investigation a cutting model and energy method considering the condition of side-curl of the chip was extended to the drilling with curved cutting edge drills. In this paper the torque and thrust force and the chip formation such as shear angle chip flow angle are measured and compared with those through theoretical prediction. In the case of the drills having concave or convex main cutting edges the predicted results are in good agreement with the experimental results. By using the measured values relating to the radius of side-curl of the chip and the chip flow angle at the midpoint of the cutting edge the cutting model including the cutting edge at the drill center enables to explain the variation of the torque chip flow angle and chip thickness along the cutting edge when the chip form changes from conical-helical chip into long-pitch helical one. As a result, it becomes clear that the whole chip formation along the cutting edge of the drill having curved cutting edges can be treated by using the values based on the chip form expanded to a plane.
In order to reveal the mechanism of the electrochemical machining process in ultrapure water, first-principles molecular-dynamics simulations of Si(001) surfaces interacting with OH molecules were carried out on the basis of the Kohn-Sham local-density-functional formalism. A plane-wave basis set was used, and the cut-off energy is 327eV(24Ry). A norm-conserving pseudopotential was also used. We adopt the standard molecular-dynamics method for the optimization of the ionic system and the preconditioned conjugate-gradient (CG) method for the quenching procedure of the electronic degrees of freedom. We determined the optimized ionic configurations and electronic distributions for OH chemisorbed Si(001) surfaces and clarify the elemental process of the chemical reactions. It was confirmed that the Si surface atom cannot bond with four OH molecules, so it cannot be etched as an Si(OH)4 molecule. In this simulation, it was also confirmed that two OH molecules react with each other producing an H2O molecule and an oxygen atom. The oxygen atom bonds with two Si surface atoms at the surface bridge site or back-bond. We concluded that the Si surface atom cannot be etched with Si(OH)4 molecule but oxidized by oxygen atom produced by two OH molecules. These results agree with the experimental results of anodic oxidation of Si surface.
This paper deals with an evaluation method of grinding conditions in centerless grinding. It is difficult to optimize the grinding conditions for minimizing the workpiece roundness error because there are lots of process parameters such as center height angle, blade angle and stock removal rate. We had proposed the waviness decrease rate as an evaluation function of grinding conditions to select the optimum process parameters automatically. To build the closed-loop control system for the process parameters, however, it is necessary to find a practical way to measure the waviness decrease rate. In this paper, the relationship between the waviness decrease rate and the dynamic components of grinding force was investigated analytically. It was found that the frequency characteristic of the waviness decrease rate shows a similar tendency to that of the dynamic components of grinding force. Grinding force measurement system was built and measurement and evaluation of the grinding force were carried out. As a result, it was confirmed that the grinding conditions can be evaluated using the dynamic components of grinding force.
In this paper, hydrothermal reaction assisted laser process was suggested. Silicon nitride (Si3N4) and cubic boron nitride (cBN) were selected as ceramics. Argon ion laser was irradiated to them in water, steam, air, vacuum, argon, and oxygen. Threshold laser power that Si3N4 could be processed in water and steam was lower than that in other atmosphere. Removed depth of laser processed single crystal cBN was twice in water and six times in steam as deep as that in air. Hydrothermal reaction was certified by detection of hydrothermal products, such as ammonium and silica ion from Si3N4, ammonium and boric ion from cBN. Binder-less sintered cBN was also enhanced by processed in steam.
The research that micro-machining of the square on the surface (100) of single crystal silicon by the machining cantilever installed in friction force microscope is presented in this paper. It was found that the machined area is changed into striking convex after the work piece is etched by KOH solution. The relation that the height of the convex depends on the machining conditions especially on the concentration of KOH solution is understood. In order to understand the contrary etching results, the structure of machined surface was analyzed by TEM(transmitting electronic microscope) and Laser Raman Method, The result that thick oxidation and beneath deterioration exisited in the surface was showed. Moreover, the efficiency of ultrasonic cleaning combined with etching to improve the roughness and removing of the remained is confirmed. And the method of maskless formation of micro-structure as the application of the experimental results is proposed.
This study shows vibration analysis results about parallel mechanism platform with tilting linear motion actuators. The parallel mechanisms, which are applied to machine tools, are mainly applied as motion unit for spindle or workpiece. Therefore, it is demanded the parallel mechanism to be less vibration. However there are few studies about vibration behavior of the parallel mechanisms. Then, we have analyzed vibration behavior of the end effector with theoretical and experimental approaches. This paper describes the vibration mode of the parallel mechanism, which was evaluated using modal analysis method, and the mode parameter that affects the machined surface.
The study deals with the manufacture of multiple-focus micro Fresnel lenses by means of non-rotational diamond cutting tools mounted on an 5-axis control ultraprecision machining center with the positioning accuracy of 1 nm and the rotational one of 0.00001 degree. Micro Fresnel lens consisting of a number of concentric circular microgrooves are in general produced by a lathe. On the other hand, multiple-focus micro Fresnel lens consisting of several micro Fresnel lenses is not notationally symmetric, thus requiring the introduction of 5-axis control ultraprecision machining center. Two-focus and three-focus micro Fresnel lenses are designed and manufactured by controlling the movement of non-rotational diamond cutting edge along the designed micro grooves at the cutting speed of 40mm/min with kerosene dripped as cutting fluid. As a result, the non-rotational diamond cutting method allows multiple-focus micro Fresnel lenses to be manufactured accurately and neatly without any burr generation.
Spin angle controlled ball lapping method developed recently, is to have an excellent performance to lap the ball, in which V-groove lapping plate are separated into two parts and three plates are able to rotate independently. However, lapping of ceramic ball such as a silicon nitride(Si3N4) ball is very hard to finish its ball. Present paper focuses on spin angle controlled grinding of the Si3N4 ball using a diamond wheel. It is found that spin controlled grinding is sufficient to finish the Si3N4 ball. Experiments show that larger spin angle θ yields both higher stock removal rate and lower surface roughness of the ball. Measurements indicate that a sphericity of the ball is closely related to spin angle θ of the ball.
In usual design process of machine products such as machine tools, most designers concentrate on the improvement of technical specification of the product. However, all products should be designed as those users' needs are realized. And the design process in which users' needs are extracted and reflect on the product should be expressed clearly. In this paper, a new design process that composes of both technology-oriented cycle and needs-oriented cycle is proposed. We call it needs-technology cycle. The design process was applied to a design of CNC lathe. The results of evaluation of the developed CNC lathe show that both user satisfaction and efficiency of user's work are improved more than an ordinal CNC lathe.
One of the problems to realize safe and highly reliable social system is to reduce the cost and time by unmanned maintenance works. In the presently available maintenance style of large-scale facilities with big and complex structure like power plant, suspension of operation and concomitant jobs like disassembly and reassembly of the object facilities are necessary. Especially in maintenance requiring access to parts assembled in narrow places like pipes inside the facility, these jobs are unavoidable. But from the viewpoint of operating efficiency, the style of maintenance and inspection without need of such disassembly and reassembly jobs is much desired. In this sense, the micromachine which can easily go into the narrow places, is expected as one of the new methods to realize unmanned maintenance. To use micromachines as intelligent actuators for operations in narrow places, it is desirable to endow micromachines with functions to move individually and to work cooperatively in a group, because the micromachine miniaturized enough to go into the narrow place is restricted in its functions, and it is difficult to realize high speed and high output jobs by a single unit. The objective of our research is to develop a control system for multi-micromachines to construct desired work patterns. In this paper, we propose an algorithm to generate desired patterns and show some experimental results.
The expert system based on Case-Based Reasoning (CBR) to select cutting condition has been developed. In CBR, a new problem is solved by a similar past case. The developed system has the case database consisting of past cases or cutting conditions of high speed milling operation performed. The case database is equivalent to the experience and the practical background of skilled engineers in the system. At first, the system retrieves similar past milling operations to the required operation using several rules which define the similarity between tool shape, work material and so on. Then, the cutting conditions in the retrieved cases are adapted to the required operation. Finally, the suitable cases among adapted one are selected to determine the cutting conditions to the required operation. The cutting conditions suggested by the system are reasonable to the various end milling operations.
In a design process, a designer uses various kinds of design object knowledge, such as physical laws, mechanism library, and manufacturing knowledge. Therefore, it is necessary for a CAD system to handle large scale knowledge bases to support this process. However, it is difficult to use a large scale knowledge base without knowledge about operations of the knowledge itself. This paper proposes a theory of design knowledge operations. First, we analyze the results of design experiments that are records of real design processes. Second, we formalize design knowledge operations based on General Design Theory. Finally we discuss the generality of the proposed formalism of design knowledge operations.
A phase φ of specklegram is a function both of an optical path difference L and wavelength λ . From this function, the optical path difference L, which is directly used to calculate a shape of an object, can be given as a function of d φ/d λ. In the proposed technique, a widely used laser diode is adopted as a wavelength-changeable light source, and its wavelength λ is scanned slowly within 0.25 nm by using current injection control of the diode. From specklegrams captured during wavelength scanning, changing amounts of φ are extracted on individual pixels with a modified phase shifting technique. Since a scanning range is very short, it is difficult to measure a changing amount of λ along each specklegram capturing. Then a reference height step is also inserted in a vision of CCD camera and changing amounts of φ are measured both on the reference step and the object. From the ratio of the total changing amounts of φ, the shape of the object is calculated. Experiments are carried out to confirm the validity of the method.
This paper proposes a method to measure the three-dimensional motion of a microscopic object. A camera observes the object and the captured images are analyzed to calculate the displacements, where the object is assumed to be rigid and its dimensions are known in advance. The formulation and procedures are established fast. Then this method is applied to the measurement of a linear motion microsystem, in which a silicon mover slides along the V grooves anisotropically etched on a silicon wafer. The dimension of the mover is 370×398×450μm. A high-speed video camera is used to adapt to the expected high-speed motion. The results show that quick angular motion occurred during short time as 10ms. Finally, the improvement of the resolution and accuracy is discussed.
This paper realized forcefree control of industrial articulated robot arm without external addition of force sensors. The forcefree control enables a motion of the industrial articulated robot arm as if it were in circumstance of non-gravity and non-friction condition. External force is detected by a torque monitor which is usually used in the servo controller of the industrial robot arm. The effectiveness of the proposed force sensor-less forcefree control was assured by simulation and experimental results of an actual industrial robot arm.
High definition and low cost are needed to further widen the use of liquid crystal displays. High-definition liquid crystal can be achieved by improving the mounting accuracy of tape carrier packages (TCPs), which are ICs that drive liquid crystal. Low-cost liquid crystal can be achieved by mounting the multiple TCPs at a time to enhance productivity. Important development challenges in accomplishing these two tasks are high precision and soaking of the bonding head in the TCPs system. An optimum bonding head shape has been obtained by thermal analysis using the finite element method (FEM).
This paper proposes a new method for rotation-invariant picture matching using an orientation histogram represented by autoregressive model. An orientation histogram is created through gradient of brightness at each pixel. The orientation histogram intersection (OHI) algorithm is effective for searching rotated patterns in the scene, but it needs time consuming circular shifting operations of a reference orientation histogram. This computational demerit increases when registration accuracy is desired. The proposed method expresses an orientation histogram by an autoregressive model as a closed contour, and it has rotation-invariance as well as OHI and then fast computation can be performed by use of the representation with smaller parameters. Experiments with real pictures show effectiveness of the proposed method.
A new type of ultraprecision positioning system using an aerostatic guideway with active control system is proposed. The control system employs an Active Inherent Restrictor (abbreviated AIR) invented by the authors. The AIR consists of a piezoelectric actuator having a through hole, one end of which is small enough to function as an orifice when the actuator is embedded in the bearing surface. By changing the length of the piezoelectric actuator, the AIR controls the air film thickness and the position of the table supported aerostatically by the guideway. Owing to aerostatic mechanism, the table displacement nominal to the guideway can be much less than the deformation of the actuator. This means that the aerostatic guideway with the AIR acts as a motion-reduction mechanism. Full stroke of the actuator is 3.5μm, while that of the table is 110nm, then the reduction ratio of this mechanism is about thirty. Dynamic step positioning of the table shows that the settling time is about 30ms and the stewing rate is about 45nm/ms. Static step positioning with various step width shows that the positioning resolution is 50pm. Therefore, the stroke is short, however, the system can be used for picometer positioning. Under step positioning of the table, an aluminum alloy mounted on the table is turned by a single point diamond tool. On the turned surface, micro steps, depth of which is 16nm, can be resolved. This shows that the positioning system can be used to control the depth of cut.
There are a lot of dangerous sloped grounds, includes rock walls, by sides of roads, railways and buildings in JAPAN. In order to prevent accidental disasters, e.g. landslides on the slope surface, the surface movement of the ground must be strictly and continuously monitored. The conventional monitoring method using targets or clinometers on the slopes requires expensive costs, huge manpower and dangerous operation on the slope. This paper shows a new monitoring method for the landslide or slope collapse, requires no targets, using a precision digital camera and image processing algorithms. Serial still images of the slope are firstly taken with the digital camera with a constant time interval. Each image is divided into small block elements. Using a block matching method, all the blocks in the image previously taken are scanned and compared in some search areas in the image subsequently taken, and movement vectors of all the blocks, which means the slope slides or deformations, can be calculated. An image subtraction function and a cross correlation method are utilized as assessment functions in the block matching method. The proposed method is applied to real images of the rock wall collapse and movement vectors are calculated. Small early translational deformation of the rock can be calculated with the method. This result shows a feasibility of the method for monitoring landslides.
A simple and economical ultrasonic measuring system of 3-D position and orientation of a robot has been proposed, and its accuracy is proved to be better than ±0.3mm in each X, Y, Z coordinate in the previous report. This system is based on distance measurement between transmitters attached to a robot arm and receivers placed around the robot working space. In this report the effectiveness of this system for the static and dynamic position measurement of a practical robot is experimentally investigated. An automatic tracking system, which predicts the next transmitting position and controls rotational angle of each receiver so as that its receiving plane faces up to the transmitter without delay, is proposed. The static positions of a 6-DOF articulated robot (PUMA robot) are measured and the obtained error distribution is similar to that obtained by a high precision laser tracking system. Kinematic parameters of a SCARA robot are calibrated and the positioning accuracy is improved. The dynamic positions of a PUMA robot on linear and cornering paths are measured and the obtained trajectories coincide fairly with these obtained by a laser tracking system and these by a pen drawing. From these results, it is experimentally proved that this system has good potential to estimate the static and dynamic performance characteristics of a robot such as positioning accuracy, path accuracy, etc.