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In the cylindrical grinding process, the residual grinding allowance is left owing to the rubbing of the abrasive grains and the elastic deformation of the grinding system caused by the large normal grinding force. Therefore, a sizing gauge is generally used to monitor the workpiece diameter during the process. However, the sizing gauge disturbs the grinding operations, such as loading and unloading the workpiece. In this study, a new method for estimating the grinding stock of a ground workpiece is proposed. In the proposed method, the grinding stock can be estimated without a sizing gauge. The removed volume of the workpiece can be calculated from the power consumption of the wheel motor, which is easily measured. Before the grinding experiments, the specific grinding energy is determined from several grinding results. During the grinding process, the grinding stock of the ground workpiece was estimated using the determined specific grinding energy. It was confirmed that the grinding stock could be accurately estimated under several grinding conditions.

During the cylindrical traverse grinding of a slender workpiece, the ground workpiece is easily bent by the normal grinding force owing to its low stiffness. Therefore, it is difficult to finish the slender workpiece with high accuracy. To prevent the elastic deformation of a workpiece during the grinding process, a steady rest is generally used. However, considerable skill of the worker is required to use a steady rest. Therefore, we developed a new traverse grinding method without any steady rest. In this method, the elastic deformation of a workpiece was kept constant by controlling the traverse speed of the workpiece. At the middle of the ground workpiece, where the elastic deformation increased easily, the traverse speed was slowed down. However, this method had a longer grinding cycle time because the average traverse speed decreased compared to that of the conventional method. To shorten the cycle time, the peripheral speed of the grinding wheel was increased to decrease the normal grinding force. Basic grinding experiments were carried out under several grinding conditions by changing the peripheral speed of the wheel. From these grinding experiments, it was confirmed that the normal grinding force and the form error of the ground workpiece decreased as the peripheral wheel speed increased. By using results obtained from basic experiments, grinding experiments involving changes in the traverse speed were carried out at two peripheral wheel speeds. The grinding cycle time was reduced successfully by increasing the peripheral wheel speed without an increment in the form error of the ground workpiece. Furthermore, a form error was observed at the end of the workpiece where the grinding wheel traveled away from the workpiece. The form error occurred because the normal grinding force decreased rapidly when the contact length between the workpiece and the wheel was decreased at the end of the workpiece. To prevent rapid changes in the normal grinding force, the traverse speed of the workpiece was increased at the end of the workpiece. By using this method, a ground workpiece with high form accuracy was obtained.

In the case of internal grinding of a deep hole, the inner surface of the hole was ground by a slender grinding wheel that has a high aspect ratio. A slender grinding wheel is bent by the normal grinding force during the grinding process. Therefore, the form accuracy of the ground workpiece is decreased especially when the aspect ratio of a wheel is high. In our previous study, it was confirmed that the biggest factor that generated the form error of the workpiece was the elastic deformation owning to the normal grinding force. To reduce the form error of the ground workpiece, it is effective to expand the spark-out duration. However, the expansion of the spark-out duration leads to the low productivity. In this study, the form of the grinding wheel was modified by a diamond dresser to improve the form accuracy of the workpiece without expanding the spark-out duration. The modified form of a wheel was determined to compensate the form error of the workpiece generated by the elastic deformation of the grinding wheel. Thorough several grinding experiment, it was confirmed that the form accuracy of the ground workpiece was successfully improved by modifying the form of a slender grinding wheel without expanding the spark-out duration.

In the case of traverse grinding of a slender workpiece, the ground workpiece is easily deformed by the normal grinding force due to its low stiffness. To reduce the form error caused by the elastic deformation of the workpiece, a steady rest is widely used. Generally, a steady rest is set to push the ground area of the workpiece. However, the stepped shape error is generated at the contact point where a steady rest pushed the workpiece because the pushing force of a steady rest is decreased after the material of the contact point is removed. In this study, to reduce the stepped shape error of the ground workpiece, we proposed a new method to set a steady rest. In this method, the steady rest was set to push the area where was not ground. In addition, the traverse speed of the workpiece was adjusted to keep the elastic deformation of the workpiece constant. The suitable method to control the traverse speed was estimated by using a beam model that could simulate the elastic deformation of the workpiece during the grinding process. It was confirmed that the new method could improve the form accuracy of a slender workpiece through grinding experiments.

In surface grinding of a large workpiece used for a sliding surface of the machine tool, high shape accuracy is required for the ground surface. Therefore, it is important to investigate the causes of the shape error observed in a large workpiece machined by surface grinding. In this study, we focused on the thermal deformation and residual stress as the causes of shape error. The in-process measurement of the workpiece temperature distribution was carried out to estimate the effect of the thermal deformation to the shape error. The estimated value of the shape error calculated from the measured temperature distribution was much less than the actual measured shape error. Therefore, the residual stress on the ground surface was measured with a portable X-ray stress measurement device. The residual stress was changed from compressed state to tensile state as the grinding pass increased. The ground shape was also deformed to concave shape as the grinding pass increased. The value of the shape error was finally reached to the constant value in several grinding conditions. From these experimental results, it is suggested that the shape error of the large workpiece is caused by the residual stress applied to the ground surface.

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.

In cylindrical traverse grinding of a long workpiece with high aspect ratio, the shape accuracy of a workpiece worsens due to its low stiffness. In this study, the grinding force was measured during grinding process to calculate the elastic deformation of a workpiece caused by the normal grinding force. By comparing calculated elastic deformation with the measured shape error of ground workpiece, the cause for the shape error in case of grinding a long workpiece was investigated experimentally. From experimental results, it is confirmed that the main factor of the shape error of the long workpiece is its elastic deformation during grinding process.

In cylindrical grinding, a sizing device is generally used to obtain the required dimension. However, the dimensional error can be caused by the thermal deformation of the workpiece even if grinding machine is controlled with the sizing device. To solve this problem, it is necessary to develop the grinding system that can consider the thermal deformation of the workpiece during grinding process. In this study, an advanced grinding system was developed, which can predict the net stock removal of ground workpiece immediately. The grinding experiment is carried out to verify the developed system.

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.

Grinding is one of the machining methods for finishing that is performed by using a large number of abrasive grains with irregular shapes and random distribution. While this feature enables accurate and high-quality machining, it complicates analysis of the grinding process. To solve this problem, a great number of computer simulations have been carried out using the Monte Carlo method. Most of them, however, statically calculate geometric interaction between a grain and a workpiece, and have not provided enough achievements for practical applications. In this study, taking this background into account, a simulation program has been developed based on the elastic support model of a grain in which the elasticity of grain support changes according to its location. The program focuses on the generation process of a workpiece surface, and simulates the interaction between grains and a workpiece, which includes the elastic and plastic deformation as well as the removal of workpiece material. Examples of the simulation shown in this study verify the fact that the simulation program facilitates analysis of the microscopic grinding phenomena, and can be used as a practical tool for predicting the grinding results and for optimizing grinding parameters.

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.

Twin axes synchronous controlled type CNC crankshaft pin grinder has been widely used, but grinding mechanism with this type of pin grinder is not cleared well. In this study, the grinding mechanism is analyzed, and it is found that the cylindrical plunge grinding process carries on. From the investigation of substantial surface speed of both the wheel and the workpiece, grinding speed ratio is formulated. Furthermore, a simulation method, which predicts the grinding results, is developed. In order to realize high precision pin grinding, two methods, which control workpiece rotation speed adequately, are proposed, such as the controlled grinding speed ratio method and the controlled residual stock method. From the analysis, it is made clear that stable grinding force and surface roughness are generated by the controlled grinding speed ratio method, and also high dimensional accracy will be realized by the controlled residual stock method.

A good part of grinding operations is still dependent on skilled operators. Against such a background, this study takes up cylindrical plunge grinding, and presents a skill-formation model based on the learning process similar to that in which a grinding operator acquires skills through trial and error. The model repeats learning by giving only the total grinding stock and initial infeed rate, changing infeed rate, and evaluating the size and the removal rate in the process end. The simulation result has proved that the model shows a skill-formation process similar to that of an operator and generates desirable infeed processes.

A learning model for the setup of grinding parameters had been developed by the authors using genetic algolithms and the fuzzy reasoning algorithm. Although the effectiveness of the model has been proven through a wide range of computer simulations, further practical investigations are required for industrial applications. In this respect, the performance of the model is investigated experimentally in this study. Since the performance of any learning model is affected by learning data, particular attention is paid to the influence of learning data. Ouality and quantity of the data obtained from the grinding process is discussed. The experimental results prove that the number of learning data has an influence on the rules obtained. Insufficient data cannot generate sufficient rules. On the other hand, an excessive amount of data degrades quality of the rules, which could be attributed to confliction of learning data.

This paper addresses a modeling method of quantitative relationships between grinding parameters and grinding results. With consideration of reasons why conventional empirical formulae are not accurate enough for practical use, a new model named the "adaptive causality model" is developed, which has adaptivity to time-varying conditions and robustness for unexpected change of conditions. As a case study, the developed model was applied to the relationship between certain dressing and grinding parameters and surface roughness of a ground workpiece, and an experimental analysis was carried out. In the experiment, wear of the edge of a single-point diamond dresser was considered as a time-varying condition. Moreover, workpieces of different material were often ground to simulate unexpected change of conditions. The experimental result proves that the "adaptive causality model" determines the quantitative relationship with sufficient accuracy in spite of change of the dresser edge and existence of some deviating data.

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.

Publisher Summary Grinding is one of the machining methods for finishing that is performed by using a large number of abrasive grains with irregular shapes and random distribution. While this feature enables accurate and high quality machining, it complicates analysis of the grinding process. In order to solve this problem, several computer simulations have been carried out using the Monte Carlo Method. Most of them statically calculate geometric interference between a grain and a workpiece, and have not provided enough achievements for practical applications. This chapter outlines the development of a simulation program based on the elastic behavior model of a grain. The program focuses on the generation process of a workpiece surface, and simulates the interaction of grains with a workpiece, which includes the elastic and plastic deformation and the removal of workpiece material. The simulation result is visualized using a three-dimensional graphics technique. The chapter illustrates an example, which verifies that the simulation program makes it easy to analyze the microscopic grinding phenomena, and can be used as a practical tool for predicting the grinding results and for optimizing grinding parameters.