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Nowadays, direct-current (dc) non-transferred arc plasma torch has drawn significant interest from both academia and industry due to the capability to process products in an efficient and convenient way. The core of this technology is to clarify and manipulate the arc behavior at the interior of the dc plasma torch to produce ideal plasma jets for processing. To solve this problem, a quasi-steady axisymmetric model is built to simulate and compare the arc characteristics in different operating conditions and different nozzle structures of the plasma torch. The results uncover distinct aspects of the study on arc characteristics, including the detection of the primary arc attachment region and its spatial features caused by the choking effect of torch structure. The thermal efficiency focused on processing substrate is also calculated in this paper for estimating the performance of plasma processing. The calculated results show that increasing the mass flow rate brings better thermal efficiency and the greatest promotion is at least 6% in the same current value, whereas improving the arc current value causes the opposite result. Meanwhile, two types of nozzle are compared to the original design in thermal efficiency, where the wide nozzle is chosen for torch optimization due to its best power efficiency. The secondary arc attachment on the metal substrate is discovered though its impact scope is only within a radius of 10 mm from the torch axis, its effect on the processing could be ignored for the extremely low electric current value.

This paper studied the air film pressure field (AFPF) characteristics of aerostatic thrust bearing, in which we proposed the measurement equipment for the 2D AFPF and successfully verified the theoretical simulation results. The experimental results agreed well with the theoretical results. However, in the area between the distribution circle of orifice to the air film outlet boundary, the experimental air film pressure (AFP) was slightly higher than the theoretical one. While for the area between the distribution circle of orifice and the center of the bearing, it showed the opposite law. Besides, the increase ratio of the AFP was close to that of the external load with its increase.

Lightning rods are effective to prevent lightning damage in power systems. However, under the influence of severe weather conditions, they often face failure problems, mainly manifested as tilt and fracture caused by bolt loosening which can result in significant economic losses. Therefore, it is very meaningful to detect the loosening of the lightning rod. The vibration-based method is an effective method for bolt loosening detection and is suitable for use on large lightning rods. This paper built a finite element model of the lightning rod Flange-Bolt Structure Unit (FBSU) based on the virtual material method, designed an effective acquisition test of the vibration signal under different loosening conditions of the lightning rod FBSU. The experimental results showed that it was effective to establish the dynamic model of the lightning rod FBSU by using the virtual material method. According to the measured vibration signal, the frequency response function was obtained by TIME MDOF method, and the preliminary judgment of bolt loosening can be realized. This study lays the foundation for the precise positioning and the extent of loosening detection of lightning rod bolt loosening, and also provides a guideline for the vibration test design of large bolted structures similar to lightning rods.

During preliminary tea processing, moisture content is an important consideration affecting the tea quality. Traditionally, the moisture content of tea leaves was manually controlled by the joint action of multiple processing units, and maintaining stability was difficult. In this paper, a multi-unit collaborative strategy was proposed for controlling moisture content in preliminary tea processing. Multivariate methods including polynomial regression, radical basis function neural network (RBFNN), and least squares support vector machine (LSSVM) were used to establish models for moisture content prediction in the first fixation, second fixation, and drying units, with minimal root mean square errors (RMSEs) of 1.34%, 0.86%, and 0.13%, respectively. The combination of RBFNN and LSSVM, with a RMSE of 0.03%, was used to model the preliminary processing of whole tea. Rough set data mining technology was used to obtain the optimum ranges of moisture content and critical process parameters. Finally, a Monte Carlo simulation experiment was carried out within the optimum range, and moisture content design spaces for the single unit and the whole processing line were obtained. With the proposed approach, the stability of the final moisture content of tea can be improved, which is of great significance for improving tea quality and accelerating the automation of tea production.

The development of air bearing demands further research and certain guidance. The previous technical reviews focused on specific aspects, while bibliometric analysis employed in this paper gave a general overview on air bearing field and provided clearer research interest and development trend. The publications in the field of air bearing from 1990 to 2017 based on the Science Citation Index Expanded (SCIE) database were analyzed from the aspects of countries, institutions, research areas, journals, authors, keywords, reviews, and high cited papers, implemented by some representative and convincing indicators. The result showed that the USA held the dominant position in this field, followed by Japan and China. The University of California System held the top position in terms of total papers and h-indexes. It had shown a multi-disciplinary development trend of air bearings from the aspect of research area. Tribology related journal took high ranking of the list, in which “Journal of Tribology-Transactions of the ASME” ranked first. Bogy, D. B., made most contributions to the air bearing field, with the highest total citations and h-index. Thermal effects, foil bearing, dynamic analysis, and active compensation were hotspots. Reynolds equation, stability, optimization, load-carrying capacity, foil bearings, and aerostatic bearings were potential directions that might have greater opportunities for improvement. The improvement of air bearing requires common progress in multiple aspects.

Human reliability analysis (HRA) and optimization in manufacturing systems are effective to reduce system failure. The purpose of this study is to examine the HRA and optimization through a Bayesian network (BN) model and human factors experiments (HFEs). This study was applied to a flexible intermediate bulk container manufacturing plant. The human physiological and psychological factors consisting of personal abilities of flexibility, coordination, memory, and attention were regarded as the only performance shaping factors in this study. With the BN model, the relationship between human factors and human errors was described qualitatively and the impact of the human factor on system failures was judged quantitatively. Then the workers’ abilities training with HFEs based on the fault diagnosis results was carried out. The total numbers of errors have been decreased by 69.06% and the system failure rate has been reduced significantly after training.

In order to study the machining mechanism and process of abrasive flow machining for the titanium alloy artificial joint surface, the abrasive flow machining experimental platform and the curved surface profiling flow channel were established for the machining. The influence of various process parameters (abrasive particle size, abrasive particle concentration, and processing time) and interaction factors on surface roughness and surface micro-topography of the workpiece was quantitatively evaluated through response surface analysis, and a surface roughness prediction model was established. The experimental results show that coverage constraint abrasive flow machining can significantly improve the surface quality of the titanium alloy artificial joint surface, thereby improving the wear resistance and service life of the artificial joint. Using abrasive flow machining with a smaller abrasive particle size and a larger concentration can obtain smaller surface roughness. Under the experimental conditions, the influence of process parameters on the surface roughness is in descending order of processing time, abrasive particle concentration, and abrasive particle size. And the interaction of processing time and abrasive particle size is more effective during processing. The research results can provide the basis for optimizing the flow channel structure for the abrasive flow machining of the titanium alloy artificial joint surface and have a certain guiding significance on the process optimization.

Dynamic vibrations of air bearing motor spindles have significant influence on the surface quality in ultra-precision machining. In this article, the influence of the vibration caused by the unbalanced magnetic force on the diamond turning is investigated on the basis of the theoretical and experimental method. A permanent magnet motor model (10 poles and 12 slots) is built and then simulated to gain a periodic unbalanced magnetic force. The effects of unbalanced magnetic force on the inclination of the spindle shaft is analyzed, which would affect the surface quality of the workpiece, and the surface topography of the workpiece is predicted during an unbalanced magnetic force acting on air bearing motor spindle. The theoretical analysis and experimental turning results validate that the angle between the direction of unbalanced magnetic force and the feed direction has a certain relationship with the profile of the machined surface. Also, under different turning speeds and directions, the surface topography of the machined workpiece shows a 10-cycle-per-revolution pattern, which has good agreement with the simulations of periodic unbalanced magnetic force. This research work provides a theoretical foundation for the fault diagnosis of air bearing motor spindle caused by motor rotor eccentricity and its effect on surface generation in turning.

Air bearing spindles (ABS) can meet high accuracy demands for the precise rotation motion, which adopt air bearings to support spindle shaft, and the spindle shaft directly connects the motor rotor. The unbalanced electromagnetic force caused by motor rotor eccentricity (MRE) and air pressure fluctuation (APF) are two important influential factors to the dynamic performance of the spindle system and machining surface quality. This paper addresses the problems of measuring the MRE and APF in an ABS through testing machining surface topography. A permanent magnet synchronous motor (PMSM) was modelled by finite element simulation (FES). Through FES it found that the MRE between the motor rotor and stator hole produced a radial magnetic force (RMF), which could cause ABS to periodically vibrate in the axial direction. Besides, the change of the air supply caused the stiffness variation of ABS and result in the tilt error motions of the spindle shaft. A theoretical model of machining surface topography considering MRE and APF was then proposed for the first time, which revealed that the MRE and APF resulted in the periodic fluctuations of the machining surface topography. The overall surface topography then became grooved surfaces. The above findings were finally validated by measurement results of ultraprecision diamond turning experiments.

During the process of tea vibration sieving, the instability of tea flow has great influence on the sieving efficiency, which contains the sieving quality and sieving productivity. In this paper, the influence factors on the sieving efficiency in tea vibration sieving were studied. Firstly, the mechanism analysis of tea vibration sieving was conducted. Through the force and motion analysis of the tea particles, the sieving model of the stripe-shape tea particles was established to study the influence of vibration angle, rotation speed and acceleration in the sieving rate. Next, the tea vibration sieving process was simulated by the Matlab/Simulink to analyze the relationship between tea flow rate, rotation speed of tea vibration sieving machine and sieving efficiency. Finally, the theoretical analysis results were well verified by the experiments. The research results provide a certain theoretical foundation for designing and improving the tea vibration sieving machine, and can be used to guide the optimization of operation parameters.

Ribbed holes can serve to increase the efficiency of the heat exchangers and improve the performance of industrial equipment. Increasing demand for small ribbed holes is a key driver in manufacturing technology research. Electrochemical machining has been shown to be a promising method for this. In this paper, an intermittent low-frequency vibration tool is used to demonstrate significant improvement to the geometry of internal ribbed holes. The process stability, material removal rates, and uniformity of features along the flow direction are improved. Firstly, a 3D model of the flow field within the interelectrode gap was developed to calculate and governing flow regime in the interelectrode gap. The simulation demonstrated that the fluid velocity fluctuates periodically and this enhances electrolyte flushing in the interelectrode gap during the machining process. Then, experimental tests for the manufacture of spiral ribs on small holes (Ø1.5 mm and 20–40 mm depth) are also demonstrated with accompanying variation of the tool vibration amplitude and frequency, respectively. Results show that groove depth was most greatly influenced by the vibration amplitude and that better uniformity could be obtained at higher vibration frequencies. The groove depth increased by 15% over nonvibrating control tests with enhanced uniformity.

The performances of aerostatic spindle are highly affected by the fluid-structure interaction (FSI) between air film and solid structure. This paper proposes a novel modeling method to investigate the FSI of aerostatic spindle system, by which the structure deformation included by air film force can be acquired. Furthermore, a virtual weight loading method is proposed to estimate the stiffness of spindle with consideration of structure deformation and gravitational eccentricity. The reliability of the proposed method is verified by experiments. Based on the proposed FSI model, the influences of air film geometrical parameters and structure dimension on the performance of aerostatic spindle are further investigated and discussed to guide the design of air spindle.

Subsurface microstructure alteration has been a major concern to implement micromachining of titanium alloy in the high-tech industry. To quantitatively promulgate the underlying mechanisms of this alteration, a discrete dislocation dynamics-based model is proposed and used to simulate the subsurface defects and their evolution under different cutting conditions. The model considers the subsurface dislocation configuration and inner stress distribution during the orthogonal cutting of titanium alloy. The results show that subsurface defect structure consists of plenty of dislocation dipoles, twining dislocation bands, and refined grains after cutting. In the primary shear zone, two different characteristics of subsurface damage layers can be found, the near-surface damage layer and deep-surface damage layer, which have different structural natures and distribution features. Moreover, it is found that high cutting speed and small depth of the cut can suppress the formation and propagation of subsurface defects. A powerful inner stress state would promote the distortion of the lattice and result in a microcrack within the subsurface matrix. The simulation results have been compared with experimental findings on the machined surface and subsurface of similar materials, and strong similarities were revealed and discussed.

In ultra-precision diamond turning (UPDT), the spindle axial drift directly affects the machining accuracy. Due to the difficulty of measuring the spindle drift during the machining process, the spindle axial drift was rarely studied. In this paper, an experimental method is used to prove and measure the existence of the spindle axial drift at the machining process, and the influence of spindle drift error on the machined surface is further studied. A mechanical model of the spindle system is considering the mass eccentricity, and the dynamic behavior of the spindle in working conditions are simulated with the mathematical model. Periodicity whirl of the spindle is found in the simulation, which is verified by the end face turning experiments. Then, the influence of the spindle vibration on surface topography is discussed, considering the spindle rotation speed and its dynamic balance. Meanwhile, the vibration frequencies induced by the spindle rotation are detected by the signal analyzer, and the detected frequency has been found to agree well with the experimental wave period of the workpiece surface (WS). This study is quite meaningful for deeply understanding the influence rule of spindle unbalanced error from the viewpoint of machined surface and vibration frequency. The research results are useful for the spindle error control and machined surface error prediction.

In ultra-precision machining field, the air motorized spindle which is composed of a motor and an air bearing, plays a major role. In air motorized spindle, the motor eccentricity between the stator and the rotor is inevitably introduced during the manufacturing process, which directly affects the machining results of workpiece surface, and this phenomenon is particularly unwanted in machining. However, little attention has been paid to the motor eccentricity of air motorized spindle. In this paper, a new integrated electromechanical coupling method for estimating unbalanced force in air motorized spindle is presented, and the effects of motor rotor eccentricity on surface topography in ultra-precision processes are analyzed. An electromagnetic-mechanical method is used to study the coupling effects between the motor rotor and the aerostatic spindle. Meanwhile, the motor rotor and the aerostatic spindle are analyzed as a whole. In order to clearly describe the electromagnetic–mechanical method, the ultra-precision spindle for potassium dihydrogen phosphate crystal machining tool is selected as the research object, and the model of air motorized spindle and motor rotor eccentricity are presented. Besides, in order to assess the impact of the radial magnetic force caused by motor rotor eccentricity on the spindle performance, a range of rotor eccentricities is calculated. Additionally, the influence of the motor rotor eccentricity on the dynamic response of spindle is further analyzed. It is found that motor rotor eccentricity has a significant influence on the spindle vibration, which dramatically reduces the processing quality. Finally, the machining experiments are carried out, and the flatness errors of the workpiece caused by the motor rotor eccentricity are obtained by the wavelet method. The experimental results are consistent with the analysis results, which verifies the reliability of this method. This study is quite meaningful for deeply understanding the influence of motor rotor eccentricity on the machined surface.

The ultra-precision spindle is the key component of ultra-precision machine tool, which largely influences the machining accuracy. Its frequency characteristics mainly affect the frequency domain error of the machined surface. In this article, the error measurement setup for the ultra-precision aerostatic spindle in a flycutting machine tool is established. The dynamic and multi-direction errors of the spindle are real-time measured under different rotation speeds. Then, frequency domain analysis is carried out to obtain its regularity characteristics based on the measurement result. Through the analysis, the main synchronous and asynchronous errors with relatively large amplitude of the spindle errors are found, and the amplitude change law of these main spindle errors is obtained. Besides, the cause of the main synchronous and asynchronous errors is also analyzed and indicated. This study deepens the understanding of ultra-precision spindle dynamic characteristics and plays the important role in the spindle frequency domain errors’ control, machining process planning, frequency characteristics analysis and oriented control of the machined surface errors.

This article presents a novel calculation method for the bearing performance of the aerostatic thrust bearing. This method is provided while taking the fluid-structure coupling effect into account. High pressure air film leads to the structure deformation, thus the bearing clearance after deformation is utilized to estimate the real bearing performance. Furthermore, the influencing factors on the bearing performance, the thrust plate’s thickness, and the orifices’ location, are investigated on the basis of the fluid-structure coupling effect. The calculation method of the best gas film thickness is deduced and presented. Experimental results for validation highlight the reliability of this method.

The frequency domain error of the machined surface in the ultra-precision machining attracts more attention for its strong relationship with the functional requirements of the workpieces. As the key component of ultra-precision machine tool, the spindle error largely influences the machined surface errors. However, little attention has been paid to the influence of spindle error on the surface error formation mechanism in the frequency domain for ultra-precision flycutting. This paper deeply studies the influence of spindle error on the frequency domain error formation of machined surface in ultra-precision flycutting. The influence analysis of the spindle error is theoretically and experimentally carried out according to two different evaluation directions of the machined surface by flycutting, i.e., cutting direction and feed direction. The KDP crystal flycutting experiment is designed and conducted for the theoretical verification. The theoretical analysis has been found to agree well with the experimental results. This study is quite meaningful for deeply understanding the influence law of spindle error from the viewpoint of frequency domain. The research results are quite useful for the spindle error control, machined surface error prediction, machining process planning, and also show the potential use for the spindle (machine tool) design.

This article presents the dynamic design and thermal analysis of an ultra-precision flycutting machine tool. The hydrostatic bearings are used both in the spindle and slide to ensure the stiffness of the machine tool. The fluid–structure interaction method is used to obtain the actual clearance changes of the hydrostatic bearing. The dynamic and thermal performances of the machine tool are analyzed considering the effect of hydrostatic bearings. The influence of the thermal effect on the static and dynamic performance of the machine tool is further studied. The prototype machine tool is built. Preliminary machining trials have been carried out and provided evidence of fluid–structure interaction method being helpful to design the ultra-precision machine tool based on the hydrostatic technology.

Relative vibration between the cutting tool and the workpiece plays an important role in the surface generation in ultra-precision diamond machining. High-frequency vibration of the cutting tool has important influence on the surface roughness error, while the low-frequency vibration of machine tool structure affects the figure error. The previous related researches mainly focus on the first-mode frequency vibration of the machine tool. However, its multimode frequency vibration is rarely discussed. In this article, the multimode frequency vibration of the machine tool and its influences on the surface generation in flycutting are studied. The experimental results have been found to agree well with the simulation results.

Ultra-precision machine tool is the most important physical tool to machining the workpiece with the frequency domain error requirement, in the design process of which the dynamic accuracy design (DAD) is indispensable and the related research is rarely available. In light of above reasons, a DAD method of ultra-precision machine tool is proposed in this paper, which is based on the frequency domain error allocation. The basic procedure and enabling knowledge of the DAD method is introduced. The application case of DAD method in the ultra-precision flycutting machine tool for KDP crystal machining is described to show the procedure detailedly. In this case, the KDP workpiece surface has the requirements in four different spatial frequency bands, and the emphasis for this study is put on the middle-frequency band with the PSD specifications. The results of the application case basically show the feasibility of the proposed DAD method. The DAD method of ultra-precision machine tool can effectively minimize the technical risk and improve the machining reliability of the designed machine tool. This paper will play an important role in the design and manufacture of new ultra-precision machine tool.

A multi-objective optimal model of a K-H-V cycloid pin gear planetary reducer is presented in this article. The optimal model is established by taking the objective functions of the reducer volume, the force of the turning arm bearing, and the maximum bending stress of the pin. The optimization aims to decrease these objectives and obtains a set of Pareto optimal solutions. In order to improve the spread of the Pareto front, the density estimation metric (crowding distance) of non-dominated sorting genetic algorithm II is replaced by the k nearest neighbor distance. Then, the improved algorithm is used to solve this optimal model. The results indicate that the modified algorithm can obtain the better Pareto optimal solutions than the solution by the routine design.

This paper presents an error budget methodology for designing and characterizing machines used to manufacture or inspect parts with spatial frequency-based specifications. In this methodology, the static and dynamic error are considered in the error budget; the static error affects the figure accuracy, while the dynamic error introduces the spatial frequency domain error. The error caused by the components of the machine tool, the cutting process and the external interference, are considered in this paper. Using the error budget, it is able to minimize risk during initial stages by ensuring that the machine will produce components that meet specifications before the machine is actually built or purchased. This methodology is used to predict and improve the performance of an ultraprecision flycutting machine tool.

The flatness of the KH2PO4 (KDP) crystal has important effect on the inertial confinement fusion system. The method to improve the flatness of KDP crystal and its implementation in the machine tool design is presented in this paper. The finite element model of the whole machine tool is built up to describe the tool tip displacement with the cutting force along the cutting path. The influence of the axial and radial bearing stiffness of the aerostatic spindle on the machined surface flatness is discussed. Furthermore, a novel adjusting mechanism which is used to adjust the squareness between the spindle and the slide is designed, and a new machining process is proposed to improve the flatness of the machined surface. The machining trials are carried out to evaluate and validate the effectiveness of the presented approach and simulation.

In spite of the large body of work on error analysis in turning, there are very few references that directly address the relationship between the original frequency content of the different dynamic errors of the machine tool and of the machining process and the resulting spatial frequency content of the machined surface. In this paper, the dynamic errors of a machine tool are classified into two categories: (a) kinematics-induced and (b) vibration-induced dynamic errors. Through a theoretical analysis, it will be shown that the spatial frequency content of the turned surface is not directly influenced by the original frequency factors of the machine dynamic error components, but by the aliased frequency factors which will be explained in this paper. On the basis of the establishment of the deterministic mathematical relationship between the frequency contents of the machine dynamic errors in the volumetric error model and the spatial frequency content of the turned surface in radial directions, a method for obtaining the frequency spectrum of the machined surface error in radial directions is given. In addition, a method to influence the number of spatial frequency components of the surface error in radial directions and to predict and control their magnitude is put forward. A case study of a flat surface turning is presented to highlight the effectiveness of the theoretical analysis and of the proposed methods. This study has potential applications in predicting and controlling the spatial content of machined surfaces, in selecting proper machining conditions, as well as in designing machine tools for applications in which strict spatial frequency requirements are placed on the workpiece surface.

The waviness errors on the machined surfaces have significant impact on the performance of optical components. Mid-spatial frequency errors (amplitude near 10 nm, wavelength about 1 mm) are found on the machined surfaces along feeding direction, and the oil pressure fluctuations of the hydrostatic slide are confirmed to be the main source which produces such waviness errors. In this article, the influence of oil pressure fluctuations on the machined surface is studied quantitatively for the first time, and the corresponding experiments are carried out. Besides, the three-dimensional surface profile simulations of workpieces considering the oil pressure fluctuations are achieved. The simulation results have been verified by the experiments on an ultra-precision flycutting machine.

The surface waviness of the KH2PO4 crystal has important influence on its optical performance, but it is difficult to simulate by the current simulation models. This article presents an integrated machining performance forecasting method, which considers the interaction between manufacturing process and machine tool and integrates the cutting simulation, machine tool dynamic performance simulation and the control system. The profile and waviness prediction on the large area are achieved by this method with short time and high accuracy. The machining trials on a fly cutting machine tool are carried out to demonstrate the effectiveness of the proposed approach.

In order to overcome difficulties in non-uniform thickness distribution and cracking failure during rectangular tube quasi-static hydroforming, a new forming technology, named as electromagnetically assisted hydroforming, is put forward. Both experiment and finite element method were conducted to investigate corner deformability and deformation pattern and its effect mechanisms. Results indicate that both corner deformability and thickness distribution are improved greatly under electromagnetic-assisted hydroforming. The reason is that deformation behavior changed after electromagnetic force application. As electromagnetic force is applied, tine petal cross sections are periodically produced and flattened. Thus, petal-like preform continues to generate and play a useful role in corner filling. Such deformation pattern overcomes friction holding back defect and results in stress state going over from tensile stress to compressive stress, which helps to avoid cracking failure and greatly improve thickness uniformity. At the same time, it also contributes to improve surface quality and decrease forming pressure simultaneously.

Flycutting is a major machining process for flat-surface machining, which is a typical intermittent-machining process. This paper is dedicated to study the influence of the intermittent-machining force on the workpiece surface generation. In the present study, some defects are identified on the machined surface and found to be corresponded to the tool-tip vibration by the dynamic analysis and the surface-generation simulation. A theoretical model is proposed to capture the dominant factor based on the characteristic. It reveals that the defects are attributed to the changing period of the intermittent-machining force and the dynamic performance of the machine tool. Hence, a surface-generation model is proposed to take account of the tool-tip vibration and the changing of the cutting locus. The simulation results have been found to agree well with the experimental results.

This paper presents the design and dynamic optimization of an ultraprecision diamond flycutting machine tool for producing flat half-meter-scale optics. A novel tool holder is designed, which can achieve micron-level axial feeding and tool angle accurate adjustment, and new technology is also used to allow alignment of the spindle axis to the horizontal-slide travel. The design and characteristic analyses of this machine tool are presented, including the static, modal, harmonic, and rotor dynamic analysis for predicting its static and dynamic performance. A prototype is built based on the analysis and FE model considering the joint parameters. The machining test shows that this machine tool can successfully produce 415 × 415-mm surfaces on aluminum and crystalline optics, with 1.3-μm flatness and 2.4-nm rms roughness. Moreover, the differences of design concepts are discussed between the ultraprecision machine tool for optical parts machining and the conventional machine tool.

The five-axis machine tools are increasingly popular for meeting the demand of machining the workpiece with growing geometric complexity and high accuracy. This paper studies the volumetric error modeling and its sensitivity analysis for the purpose of machine design. The volumetric error model of a five-axis machine tool with the configuration of RTTTR is established based on rigid body kinematics and homogeneous transformation matrix, in which 37 error components are involved. The sensitivity analysis of volumetric error regarding 37 error components is carried out respectively. The analysis results are successfully used for the accuracy design and manufacture of a five-axis ultra-precision machine tool. The preliminary experiment of machining sine grid surface testifies the high accuracy and effectiveness of the designed five-axis machine tool.

This paper has designed a robust discrete gain scheduling controller for the linear systems by considering the parameter uncertainties and input saturation based on the invariant sets and linear matrix inequalities(LMIs). The proposed method can improve the dynamic performance by introducing a parameter. By the Lyapunov approach and the scheduling technology, the existence conditions for admissible controller are formulated in the form of LMIs. The numerical simulations illustrate the effectiveness of the proposed method.

The article presents a dynamic design approach of an ultra-precision machine tool based on the morphology requirements of the workpiece. Compared with common parts, optical parts not only have as many high requirements for surface finish and flatness, but also topographic properties, which leads to a big difference in design with traditional machine tools. This approach, from the topographic properties and functional requirements of the workpiece, demonstrates how to design and analyze the kinematic chain and configuration of the machine tool. Then, a finite element model and mathematical model are established to predict the topographic properties of the workpiece. The design and optimization of an ultra-precision flycutting machine tool is employed as a case study to elaborate the approach in detail. Preliminary machining trials have been carried out and provided evidence of the approach being helpful to design and optimize the ultra- precision machine tool used for optical parts machining.

In some industrial fields, the workpiece surface need to meet not only the demand of surface roughness, but the strict requirement of multi-scale frequency domain errors. Ultra-precision machine tool is the most important carrier for the ultra-precision machining of the parts, whose errors is the key factor to influence the multi-scale frequency domain errors of the machined surface. The volumetric error modeling is the important bridge to link the relationship between the machine error and machined surface error. However, the available error modeling method from the previous research is hard to use to analyze the relationship between the dynamic errors of the machine motion components and multi-scale frequency domain errors of the machined surface, which plays the important reference role in the design and accuracy improvement of the ultra-precision machine tool. In this paper, a fourier transform based dynamic error modeling method is presented, which is also on the theoretical basis of rigid body kinematics and homogeneous transformation matrix. A case study is carried out, which shows the proposed method can successfully realize the identical and regular numerical description of the machine dynamic errors and the volumetric errors. The proposed method has strong potential for the prediction of the frequency domain errors on the machined surface, extracting of the information of multi-scale frequency domain errors, and analysis of the relationship between the machine motion components and frequency domain errors of the machined surface.