Moriaki Sakakura

A Neural Network Approach to the Decision-Making Process for Grinding Operations

Summary In this paper, a decision making process model for grinding operations is proposed. It has a multistage structure and consists of different two types of neural network : the Feed-Forward network and the Brain-State-in-a-Box network. As an application example of the model. the relationship between the dressing conditions and the surface roughness of ground components is simulated. The results indicate that the proposed model is capable of learning the stochastic data of surface roughness and recalling the dressing conditions which attains the required surface roughness. The simulated process can be considered to be quite similar to the decision making process of experienced operators.

Intelligent Data Base for Grinding Operations

Summary This paper describes an intelligent data base system which performs an intelligent task like a skilled operator. The system consists of a grinding data base, a grinding rule base, a learning module and a reasoning module. The learning module extracts relationships between set-up parameters and results from grinding examples stored in the grinding data base using genetic algorithms. These relationships are expressed in the form of a fuzzy production rule and stored in the grinding rule base. The reasoning module provides suitable dressing and grinding parameters using those rules. A computer simulation is performed to confirm the effectiveness of the proposed system.

Form-Shaping Systems of Machine Tools: Theory and Applications

Abstract The form-shaping process is the main functional process performed by a machine tool. A theory of the form-shaping system (FSS) investigates interrelationships between, on the one hand, geometry and kinematics of the machine tool and, on the other, geometry and accuracy of the machined part. In this paper, the FSS theory is developed in the following ways: (1) the general approach spreads also to the FSS with parallel-type links (previously, only chain-type systems were discussed); (2) direct and inverse form-shaping problems are formulated.

Temperature distribution in a workpiece during cylindrical plunge grinding

In cylindrical plunge grinding, a large amount of heat flows into the workpiece continuously, accumulates and remains even after the process, which causes dimensional error. Therefore it is necessary to investigate the temperature distribution in the workpiece during grinding and analyze the influence of grinding heat on the dimension. Such an investigation has not been done enough, because the technology to measure the temperature distribution in the rotating workpiece has not matured. Considering such background, an in-process measuring system has been developed, which makes it possible to detect the temperature distribution in a wide range from the outer surface to the inside of the rotating workpiece. The system consists of small temperature sensors which are embedded into the workpiece, a micro computer attached on the workpiece which acquires the data from the sensors and transmits to a personal computer by a wireless communication device. Furthermore the contact type thermocouple which enables to measure the rotating surface temperature is added to the system. Measurement experiments revealed that the grinding heat conducts from the workpiece surface toward the center, accumulates, and remains in the workpiece even after the process. Heat conduction simulation was also performed. Good agreement was achieved between the simulated temperatures and experimental measurements.

Numerical Analysis for Thermal Deformation of Workpiece in Cylindrical Plunge Grinding

During the last decades, heat generation in grinding is one of the top concerns because high temperature under fabrication leads to less dimensional accuracy of a workpiece. Several studies with regard to grinding heat have been carried out, focused on micro phenomena of abrasive grains or macro phenomena of thermal deformation in grinding machines. However, these researches have been extensive, schematized information such as thermal deformation, and grinding temperature is indispensable for practical applications. In this study, we combined the simulation model of the plunge grinding process and the numerical analysis method with the differencing technique for the non-steady heat conduction problem, and have constructed the simulation technique for analyzing the heat problem in the workpiece. The simulation results provided information of the heat conduction, and the thermal deformation of the workpiece.

612 Improvement of accuracy in traverse grinding of a slender cylindrical workpiece

1. はじめに 軸部品の高精度な仕上げ加工には一般的に研削加工が行 われる.特に軸部品の中でも径に対して全長が長い「長尺」 と呼ばれる工作物の加工はトラバース研削で行われること が多い.長尺工作物は曲げ剛性が低いため,研削時の抵抗に よってたわみが生じやすく,工作物が砥石から逃げるために 実質的な切込み量が減少する.しかも,工作物の曲げ剛性は 軸方向の位置に応じて変化し,両端のセンタ近くに比べて中 央部分が低くなるため,工作物の仕上げ径が中央部で大きく なり,結果的に太鼓状になることがある.このような精度の 低下に対して,加工条件を調整したり,場合によっては振れ 止めを使用したりして工作物のたわみを抑制することが行 われる.しかし,そのような作業には熟練者の技能が要求さ れ,時間も要する.このような現状を踏まえ,本研究では長 尺円筒工作物のトラバース研削を対象に,加工精度を向上さ せるための加工条件の設定方法の確立を目指す.本報告では, そのツールとして構築したトラバース研削シミュレーショ ン・モデルについて述べ,その有効性を示す.

Simulation Analysis and In-Process Measurement of the Workpiece Temperature Distribution in Large Surface Grinding

In surface grinding, the shape error is occurred by the thermal deformation of a ground workpiece. To finish the workpiece with high accuracy, it is necessary to understand the temperature distribution of the workpiece during grinding process. However there is no study to analyze the temperature distribution of a large workpiece during surface grinding process. In this study, an advanced simulation analysis method of the temperature distribution for a large workpiece was developed. In the developed simulation analysis method, the temperature distribution was calculated from the power consumption of the wheel motor. The power consumption can be obtained easily without any specialized equipment. To evaluate the developed simulation analysis method, in-process measurement of the temperature distribution of a large workpiece was also carried out. A large workpiece ground in this study weights about 1.3 tons. The temperature distribution was measured with thermistors mounted in many places of the ground workpiece. At the area close to the grinding surface, it was found that temperature rises immediately after the passage of grinding wheel with measuring the developed in-process measurement system. On the other hand, at the area far from the grinding point, temperature does not change quickly. The in-process measured temperature distribution agreed well with the simulated results.