Thermal Deformation Of Workpiece Research Articles

Thermally induced comprehensive error modeling and compensation for gantry machine tools with grating scale in large structure machining

In large structure machining by gantry machine tools, the long machining duration with large temperature variation affects the machining accuracy significantly. To reduce the machining error of large structure, a method to model and compensate thermally induced positioning error considering workpiece thermal deformation is proposed. The thermal expansion of the grating scale and the thermal deformation of the workpiece are first analyzed theoretically, and a mathematical model of the positioning error and workpiece deformation error is proposed. The comprehensive model is with regard to transient temperature data of particular sensors. Compensation experiment was conducted on a three-axis gantry machine tool, and the error compensation system was applied to large structure machining to verify the effectiveness of the comprehensive error model considering workpiece thermal deformation. And the machining accuracy after compensation was greatly improved over 60%, which indicates the practicability of the proposed modeling method. It shows great potential application in large structure machining.

Development of intelligent machining system with laptop computer that can consider thermal deformation of workpiece in cylindrical grinding

Development of intelligent machining system with laptop computer that can consider thermal deformation of workpiece in cylindrical grinding

Development of Intelligent Grinding System Considering Thermal Deformation of Workpiece in Cylindrical Grinding

Development of Intelligent Grinding System Considering Thermal Deformation of Workpiece in Cylindrical Grinding

Nanofluid as coolant for grinding process: An overview

This paper reviews the recent progress and applications of nanoparticles in lubricants as a coolant (cutting fluid) for grinding process. The role of grinding machining in manufacturing and the importance of lubrication fluids during material removal are discussed. In grinding process, coolants are used to improve the surface finish, wheel wear, flush the chips and to reduce the work-piece thermal deformation. The conventional cooling technique, i.e., flood cooling delivers a large amount of fluid and mist which hazardous to the environment and humans. Industries are actively looking for possible ways to reduce the volume of coolants used in metal removing operations due to the economical and ecological impacts. Thus as an alternative, an advanced cooling technique known as Minimum Quantity Lubrication (MQL) has been introduced to the enhance the surface finish, minimize the cost, to reduce the environmental impacts and to reduce the metal cutting fluid consumptions. Nanofluid is a new-fangled class of fluids engineered by dispersing nanometre-size solid particles into base fluids such as water, lubrication oils to further improve the properties of the lubricant or coolant. In addition to advanced cooling technique review, this paper also reviews the application of various nanoparticles and their performance in grinding operations. The performance of nanoparticles related to the cutting forces, surface finish, tool wear, and temperature at the cutting zone are briefly reviewed. The study reveals that the excellent properties of the nanofluid can be beneficial in cooling and lubricating application in the manufacturing process.

Minimization of dimensional error using simulation analysis of workpiece thermal deformation during cylindrical grinding

Minimization of dimensional error using simulation analysis of workpiece thermal deformation during cylindrical grinding

Development of intelligent cylindrical grinding system considering thermal deformation of workpiece

Development of intelligent cylindrical grinding system considering thermal deformation of workpiece

A molecular dynamics investigation into the mechanisms of material removal and subsurface damage of nanoscale high speed laser-assisted machining

Molecular dynamics is employed to study the mechanism of material removal and subsurface damage of monocrystalline silicon when it is under a nanoscale high-speed laser-assisted grinding of a diamond tip. Laser-assisted machining (LAM) is that the workpiece is locally heated by an intense laser beam before material removal. The effects of laser moving speed, laser pulse intensity and laser spot radius are thoroughly investigated in terms of atomic trajectories, phase transformation, temperature distribution, grinding temperature, grinding force and friction coefficient. The investigation shows that a higher laser moving speed reduces the subsurface damage and improves the material remove rate because of fewer atoms with five and six coordination atoms and more chips. Besides, both tangential grinding force (Fx) and normal grinding force (Fy) decrease as the laser moving speed increases. The distribution of high-temperature zone strongly depends upon the effect of laser pulse intensity and laser spot radius. Larger laser pulse intensity can make the material more fully softened before being removed. Moreover, as the laser pulse intensity becomes larger, the friction coefficients became smaller, the material remove rate improves and the depth of grinding increases. However, larger laser pulse intensity may result in a larger thermal deformation of workpiece. A larger laser spot radius reduces the grinding depth but increases the width of laser irradiation zone on machined surface. Thus, a suitable laser spot radius can improve the material removal rate. These results indicate that it is possible to control and adjust the laser parameters according to laser moving speed, laser pulse intensity and laser spot radius, and it provides a potential technology to improve a surface integrity and a smoothness of ground surface.

Thermal error compensation of dry hobbing machine tool considering workpiece thermal deformation

Dry hobbing is a new gear tooth forming process, which would replace the traditional wet hobbing process due to its high efficiency and environmental friendliness. However, due to the absence of metal cutting fluid in dry hobbing, temperature of hobbed workpiece is relatively high, which will lead to the increase of dimension errors, especially tooth thickness errors. In this paper, the features of workpiece thermal deformation errors are identified and an error compensation model is developed to compensate both machine tool thermal errors and tooth thickness errors which is induced by workpiece thermal deformation. In this model, the representative temperature variables of a dry hobbing machine tool are obtained based on experimental data with fuzzy clustering method. A compensation model is proposed to map the relationship between representative temperature variables and compensation value. In a series of experiments, the tooth thickness errors ranged from −22 to −59 μm. After implementing compensation of machine tool thermal errors, the tooth thickness errors ranged from −18 to −28 μm, which demonstrates that workpiece thermal deformation has a great influence on tooth thickness errors in dry hobbing. Furtherly, the tooth thickness errors ranged from −4 to 8 μm, after implementing compensation of both machine tool thermal errors and workpiece thermal deformation errors, which demonstrate that the compensation model is effective.

A Quality Function Deployment-Based Model for Cutting Fluid Selection

Cutting fluid is applied for numerous reasons while machining a workpiece, like increasing tool life, minimizing workpiece thermal deformation, enhancing surface finish, flushing away chips from cutting surface, and so on. Hence, choosing a proper cutting fluid for a specific machining application becomes important for enhanced efficiency and effectiveness of a manufacturing process. Cutting fluid selection is a complex procedure as the decision depends on many complicated interactions, including work material’s machinability, rigorousness of operation, cutting tool material, metallurgical, chemical, and human compatibility, reliability and stability of fluid, and cost. In this paper, a decision making model is developed based on quality function deployment technique with a view to respond to the complex character of cutting fluid selection problem and facilitate judicious selection of cutting fluid from a comprehensive list of available alternatives. In the first example, HD-CUTSOL is recognized as the most suitable cutting fluid for drilling holes in titanium alloy with tungsten carbide tool and in the second example, for performing honing operation on stainless steel alloy with cubic boron nitride tool, CF5 emerges out as the best honing fluid. Implementation of this model would result in cost reduction through decreased manpower requirement, enhanced workforce efficiency, and efficient information exploitation.

Grinding System Reducing the Influence of Thermal Deformation of Workpiece in Cylindrical Grinding

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.

The Numerical Simulation for Thermal Deformation in Grinding Hardening Thin Workpiece

The high temperature in grinding hardening induces workpiece thermal deformation. The thermal deformation causes a concavity on the ground profile and affects the grinding hardening depth. The paper uses ANSYS thermo-mechanical coupling module to simulate the thermal deformation in grinding hardening. The workpiece profile by simulated is compared with the test result.

Analysing the effect of cutting fluids on the mechanical properties of mild steel in a turning operation

Cutting fluids are used in machining for a variety of reasons such as improving tool life, reducing work-piece thermal deformation, improving surface finish. Mota and Machado (1995) concluded that reducing cutting tool cost and increased production can be achieved through the use of appropriate cutting fluids. In this work soluble oil, water and palm kernel oil were used as coolants in turning operations. Tungsten carbide and HSS cutting tools were employed as cutter with cutting speed of 355rpm. Turning was done under dry condition and also using 3 coolants. Temperature and Hardness values after each cut were recorded. The microstructure of all the specimen was also done and recorded. It was revealed that variation in the Hardness value of the samples with progress in machining time is more with the use of carbide tool compared to the HSS cutter .Samples cooled with water exhibited the highest hardness value. Palm kernel oil performed very well the specific functions of soluble oil as cutting fluid which includes good chip formation, reduction of heat generated and realization of a good surface finish The analysis are shown in tabular and graphical form in chapters 3 and 4

C23 円筒プランジ研削における工作物熱変形量の測定とシミュレーション解析(第1報) : 温度分布を考慮した熱変形量のシミュレーション解析(OS7 研削・砥粒加工(1))

The dimensional accuracy of workpiece worsens because of thermal deformation by grinding heat in the cylindrical grinding. Therefore, it is necessary to understand thermal deformation behavior of the workpiece, but temperature changes in the workpiece are not clarified sufficiently. In this study, temperature distribution and thermal deformation of workpiece are simulated, and validity of these simulated results was verified with comparing to measured results by developed measurement system of temperature in the workpiece.

C24 円筒プランジ研削における工作物熱変形量の測定とシミュレーション解析(第2報) : 表面温度の測定結果を用いた熱変形量の算出(OS7 研削・砥粒加工(1))

C24 円筒プランジ研削における工作物熱変形量の測定とシミュレーション解析(第2報) : 表面温度の測定結果を用いた熱変形量の算出(OS7 研削・砥粒加工(1))

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.

Improvement of flatness error in milling plate-shaped workpiece by application of side-clamping force

To improve flatness error of plate-shaped workpieces in milling under side clamp holding mechanisms, appropriate magnitudes of clamping forces and method of application are studied in this paper. The effect of side-clamping force on workpiece deformation is investigated by experimental and computational analyses for the case where the workpiece is clamped at a position higher than the neutral plane of bending of the plate-shaped workpiece. It is found that the thermal deformation and elastic deformation caused by clamping force are in two opposite directions. Then, an appropriate method is proposed to compensate for the workpiece thermal deformation caused by cutting heat with the opposite elastic deformation caused by the side-clamping force, so as to keep the machined top surface of the workpiece flat as much as possible. The proposed method has been confirmed through computational analyses and experiments. © 2000 Elsevier Science Inc. All rights reserved.

表面粗さの改善を促進させる熱変形速度制御研削法

In this paper, a new grinding technique, the thermal deformation rate control grinding, in which the thermal deformation rate of workpiece is controlled by changing the fluid flow rate at the beginning of spark-out state, is proposed in order to improve remarkably the surface roughness of workpiece. Main conclusions obtained as follows : (1) From a viewpoint of the surface roughness improvement, the most suitable fluid flow rate exists in spark-out state. For example, the surface roughness of workpiece can be improved 32 % at the point of 10 s spark-out time when the fluid flow rate is changed from 15L/min to 3L/min comparing with the constant fluid flow rate 15 L /min. (2) The surface roughness improvement'process in the thermal deformation control grinding is made clear by considering the relationship between the actual size generation rate and the surface roughness rate of workpiece. (3) An in-process measurement method by which the thermal deformation of workpiece can be estimate, is developed to make clear the surface roughness improvement process.

Accuracy of work-pieces produced by one-pass creep feed grinding

Work-piece profile and dimensional errors are caused by the following three major factors: elastic deflection between wheel and work-piece, wheel wear, and thermal deformation of work-piece. This paper aims to clarify comprehensively and quantitatively the effect of these factors on the accuracy of a work-piece produced by one-pass creep feed grinding ( cfg). Among these factors, the effect of the thermal deformation of the work-piece has not been well understood because of the inherent difficulty in predicting the temperature distribution of the work-piece. In the present study, the work-piece temperature distribution is analysed by a three-dimensional finite element method ( fem) where the cooling effect of the coolant is measured and the energy transfering as heat into the work-piece is timated by Jaeger's moving heat theory extended to include the cooling effect. From this, the thermal deformation of the work-piece is estimated by Jaeger's moving heat theory extended to include the cooling effect. From this, the thermal deformation of the work-piece is also predicted by fem.

研削熱による変形が寸法生成過程に及ぼす影響の研究

The size generation process in cylindrical plunge grinding is experimentally analyzed, taking the thermal deformation of workpiece into account. The thermal deformation of workpiece is first measured to make clear the variation of the thermal deformation of workpiece in one cycle of plunge grinding. The thermal deformation of workpiece increases in spark-in state, becomes constant in steady state and then decreases in spark-out state of plunge grinding. The thermal deformation rate of workpiece is then discussed to make clear the actual size generation rate, which is affected by the feed rate of wheel head and the thermal deformation rate. The actual size generation rate increases abruptly in spark-in state because of the thermal expansion of workpiece, and decreases significantly in spark-out state because of the thermal contraction of workpiece.

クリープフィード研削の加工精度

This paper aims to clarify comprehensively and quantitatively the effects of elastic deflection between wheel and workpiece, wheel wear and thermal deformation of workpiece on the profile and dimensional errors of workpiece which is produced in one pass creep feed grinding. The elastic deflection is determined from the experimentally obtained static stiffness between wheel and workpiece during grinding. Effects of grinding conditions on the wheel wear are examined experimentally, and it is shown theoretically and experimentally that the radial wheel wear depends almost solely on the metal removal. Workpiece temperature distribution is analyzed by using the finite element method and it is revealed to agree with the experimental result. From this the thermal deformation is calculated by the FEM. It is shown that the resultant errors coincide well with the actual profile and dimensional errors of workpieces. Effects of profiled wheel wear and the thermal deformation of workpiece being profile ground are also considered.