Masahiro Mizuno

Optimal strategies for corrective assembly approach applied to a high-quality relay production system

Abstract In the assembly of high-quality products in a corrective assembly approach, measurement and reprocessing errors occur in the measuring and reprocessing stages, and these unexpected errors can lead to the erroneous selection of the reprocessing machine, and produce unsatisfactory products. In this paper, we consider the part flow in a high-quality relay production system applying the corrective assembly approach by incorporating machining, measurement and reprocessing errors simultaneously, and formulate the production rate of high-quality products satisfying the predetermined assembly tolerance. Optimization is used to yield the maximum production rate by using reprocessing machine selection and design strategies. The results indicate the following: (1) the proposed optimization methodology effectively yields the maximum production rate and presents the optimal selection range and the optimal adjustment size of the reprocessing machine, and (2) the reprocessing accuracy affects the maximum production rate but has little effect on the optimal selection range and the optimal adjustment size.

Development of a Device for Measuring the Transverse Motion of a Saw-Wire

The transverse motion of a saw-wire affects the cutting surface geometry in wire-saw slicing. To evaluate the magnitude of the wire transverse motion under no-slurry and no-workpiece conditions, which should be minimized before starting the slicing process, a high accuracy, noncontact device has been developed. The measuring head of the device is composed of a laser diode module and a dual-element photodiode between which a saw-wire is placed for measurement. This paper elucidates the appropriate positional configurations of the photosensitive surface of the dual-element photodiode and the laser beam focal point with respect to the 160 μm diameter wire in the laser beam direction. Furthermore, a measurement experiment is carried out on a wire-saw machine under no-slurry and no-workpiece conditions. The paper reports and discusses the critical issues, such as measurement sensitivity, linearity, and accuracy.

Development of Electric Rust Preventive Machining Method - Correspond to Difference of Water in World: Use of Deionized Refined Water

Grinding fluid & cutting oil are contained various chemicals. Waste fluid treatment causes huge disposal cost and heavy environmental load. This investigation proposes the electric rust preventive machining method system that water is used as machining fluid. However, there are various problems for this practical use. In this paper, using and re-using of machining water are considered. Water quality is different in various foreign regions for containing impurity ingredient varying with each area. Correspond to water difference, water purification and deionization is examined in developed machining water refine recycle system experimentally. Synthesized water that is likened to hard water is composed from refined water (pure water which is made by water recycle system). And, it is confirmed that synthesized water is refined to deionize by water recycle system. Moreover, 12.25L/min refined water is achieved. In addition, it is indicated that electric rust prevention is possible by refined water at least 1hour. However, high voltage and device twist is necessary.

Development of Electric Rust Preventive Machining Method - Correspond to Difference of Water in World: Use of Adjusted Synthesized Water

For low environmental load and decreasing waste fluid disposal cost, the electric rust preventive machining method that uses only water as machining fluid has been developed. However, there are several problems for this practical use. In this investigation, for using this method in various regions of the world, reset and synthesis of water quality that is different in regions for containing impurity ingredient and water hardness is examined. At first, water is deionized and purified with water refine recycle system. Afterward, synthesized water is reproduced. Hardness and conductivity is adjusted in water by addition of very small amount of natural hardness ingredient CaSO4. Consequently, even if water is different, constant quality of the water can be always secured anywhere in world. Furthermore, electric rust prevention is achieved 3hours with adjusted 100S/cm synthesized water. However, adhesion derived from anode is appeared in workpiece 2hours. It is possible that the electric rust preventive machining can be carried out stability anywhere in world.

A corrective assembly method using a buffer in a high-precision machining-assembly production system

Electric relay manufacture and assembly is an example of high-precision machining followed by an assembly process. During machining, parts exhibit dimensional variance and manufacturers have several techniques and strategies for how to maximise production and improve efficiency when variance is present. One approach is to measure the variance, select parts appropriately for the best match, perform the minimum amount of adjustment and rework, and then perform the assembly. This approach is difficult in practice because measurement errors also occur and confound the knowledge about each parts dimensions. In this paper, we consider a new matching approach to increase the production rate. We propose a part-combination selection method in which a pair of assembly parts in buffers is optimally selected using a target of an estimated assembly error, and an adjustment machine is then optimally selected using a range of estimated assembly errors. Furthermore, we consider an analytical approach to estimate the optimal control parameters for the proposed method that yield the maximum production rate. The analysis results show that the analytical approach can estimate the nearly optimal control parameters, including the nearly maximum production rate in any buffer capacity. The results also show that by installing a small buffer capacity, the production rate can be increased.

Development of Electric Rust Preventive Machining Method -Water Using for Machining: Improvement of Water Recycle System-

Currently, the machining fluid includes several chemicals such as cutting oil and grinding oil is used for the machining. However, such the machining fluid that is caused enormous disposal cost and environmental load, should reduce using. Therefore, in this investigation, electric rust preventive machining method which uses only water for machining fluid is developed. Because using only water without extreme pressure agents, oil and so on, this method decreases disposal of waste machining fluid. In this paper, the system to remove impurities from a used machining fluid, and to reuse machining fluid is designed. To reproduce water efficiently, the order of arranging the filter is changed. In consequence, it has been efficient when the filtration filter is set up first, and the activated carbon filter is set up in the second. In addition, the reproduction of the water when the supply pressure is 0.75 MPa is verified by using this system. As a result, the water which passed a water recycle system, the impurities such as iron, conductivity, turbidity, colour decreased, and purification of the water is possible for this system. And, 5.2 L/min refined water recycle is achieved.

Lapping of electrical discharge machining processed tool steel surface using elliptical tool motion

A prototype lapping machine, which finishes surfaces by applying elliptical motions to a lapping tool in the presence of diamond compound, is developed. This paper describes the structure of the lapping machine, the 2-dimensional tool motions measured on the machine, the behavior of the diamond compounds between the tool and lapping surfaces, and the fundamental lapping performance. The tool motions are measured using a laser Doppler vibrometer and the proportional constants that are needed to obtain an objective tool motion are determined with the regression technique. The motion behavior of the diamond abrasive grains for each tool motion is directly observed with a microscope through a glass plate. Lapping experiments are conducted under the conditions with and without the work-feed. After lapping, the workpiece surface is measured using a surface profilometer for surface roughness and profile information. As a result, a surface roughness of less than 0.1 μmRa is achieved using a 3 μm compound and near-circular tool motion of 12.5 μm radius.

Development of a New Truing Device Based on Electro-Contact Discharge Machining for Metal Bond Grinding Wheels

Metal bond grinding wheels can retain their shape and size under extreme grinding conditions. On the other hand, it is difficult to true them accurately and efficiently due to the severe wear of truing tools. To solve the problem, this paper proposes a new truing device based on electro-contact discharge machining. The device is designed so that the position of the electrode working face remains unchanged even if the electrode is worn. Some truing experiments were carried out using a prototype truing device for a metal bond diamond wheel of grain size #1000 under dry conditions. As a result, relatively high truing accuracy has been achieved in combination with an additional truing by a GC stone.

Grinding Characteristics of Waspaloy with High-Speed Reciprocation Grinding

Grinding machines that employ a high-speed reciprocating worktable or wheel head are known as high-speed reciprocation grinding. Grinding heat generated in the high-speed reciprocation grinding process is low. Therefore, it is considered that the high-speed reciprocation grinding is suitable for grinding material of low thermal conductivity. In this study, the high-speed reciprocation grinding is applied to grind nickel-based super alloy “Waspaloy” which is known as difficult-to-cut material. And grinding characteristics of Waspaloy are investigated. As a result, it is found that the effect of grinding heat is smaller than the effect of grain depth of cut in grinding process of Waspaloy.

Development of electric rust preventive machining method system – safe water using for machining fluid: complete removal of bacteria (Legionella pneumophila) and assay

In manufacturing, machining fluid as cutting oil or grinding fluid is used for machining. This fluid contains several chemicals such as oil, surface active agent, extreme pressure agent (chlorine, phosphorus, sulphur, etc.), rust preventive agent, antiseptic agent, germicide and so on for improvement machining performance. However, it is not good for human body and environment. It is afraid that workers health hazard is occurred by fluid mist absorption in breath and splash contacting. In addition, waste fluid needs disposal treatment (incineration or coagulative precipitation and landfill, etc.) that is high cost and heavy environmental load. Therefore, environmental friendly and harmless machining is proposed for nanomanufacturing and green manufacturing. The electric rust preventive machining method system is developed in this investigation. This method system use only water (tap water, under ground water, industrial water) as machining fluid. Water only machining lead to greatly decreasing of waste fluid treatment and petroleum oil resources saving. In addition, complete removal of bacteria (Legionella pneumophila) for safe machining water by improvement water recycle system installed reverse osmosis membrane and ultraviolet radiation unit with non-using chemicals is evaluated by biological cultivation assay. And artificially contaminated tank water bacteria amount tendency is estimated.