Добірка наукової літератури з теми "Spindle axis reducer"

This paper presents a method to quantify and reduce thermal asymmetry of motorized spindles. Thermal asymmetry leads to angular and radial deflections at the tool center point. In contrast to simple thermal expansion issues, these effects are harder to compensate. Therefore, the causes of the asymmetries should preferably be evident in the construction phase. This paper introduces a newly developed mathematical formulation to quantify thermal asymmetry. Thermal asymmetry is observed along the longitudinal axis of a motorized spindle. The formulation quantifies thermal asymmetries as a difference of a geometrical centroid and a newly introduced thermal centroid. For this analysis, several motor spindles with different fluid cooling circulation systems were observed. In order to show the legitimacy of the formulation, the spindle’s calculated thermal asymmetries are compared with their respective radial tool center point displacements. The results show that the asymmetries correlate with the displacements. Furthermore, the quantification of the thermal asymmetry actually allows to locate its causes. In motor spindles the asymmetry is mostly caused by the complex fluid circulation system. The spindle with the worst cooling circulation showed a radial displacement of 26,32 µm. Through thermal asymmetry optimization of the circulation’s heat transfer, the displacement could be reduced to 0,66 µm. The developed method is not limited to motorized spindles. It will be investigated further to develop a generally valid formulation.

Electrical slow waves from cat or rabbit small intestine show more variability when recorded in vivo than in vitro. One pattern of variation is waxing and waning of amplitude, or "spindling," during which two rhythms of slightly different frequency come in and out of phase. Fourier power analyses of slow waves during spindles show two frequency peaks of slow waves differing by 0.4-5.0 waves/min and corresponding to measured spindle durations of 12-150 s. Spindles can be induced in vitro in rabbit intestine by K depolarization of approximately 15 mV. Histograms of intracellular recordings of slow nonspindling waves show variation of 0.5-1.0 s on either side of a mean slow wave duration. Spindles are abolished by treatments that reduce electrical coupling between cells, e.g., hypertonic sucrose or lowered pH, but changes in calcium do not alter spindles. Simultaneous recordings by two electrodes in the longitudinal axis show synchrony of spindles at 2- to 3-mm but not at 5-mm separation and synchrony circumferentially to the opposite side of a segment. Contractions, both in vivo and in vitro, correspond with electrical spindles in amplitude. Spindle durations were significantly shorter in vivo than in vitro, indicating a significantly greater difference in vivo in the competing frequencies at the point of recording (P less than 0.01). Three conditions favoring waxing and waning are slight depolarization, variation in slow wave frequency at a point, and electrotonic coupling between muscle fibers. Spindles provide for rhythms of contractions of a 1- to 2-min period.

This paper proposes a calibration method for continuous measurements with a double ball bar (DBB) used to identify the position-dependent geometric errors (PDGEs) of the rotary axes of five-axis machine tools. The different DBB installation modes for the rotary axes of the spindle and workbench are established, and the same initial DBB installation position is used for multiple tests. This approach minimizes the number of required DBB installations, which increases the measurement efficiency of the PDGEs of the rotary axes and reduces installation errors. PDGEs identification based on the adaptive least absolute shrinkage and selection operator (LASSO) method is proposed. By assigning coefficients to the PDGEs polynomial, the ill-conditioned problem of the identification process can be effectively avoided, thereby improving the identification accuracy. The measurement and identification methods proposed in this paper are verified by experiments on a five-axis machine tool. After compensation, the PDGEs are obviously reduced and the accuracy indexes of the circular trajectory tests performed under multiaxis synchronous control are obviously improved.

In the wood engraving industry, the double swing motor spindle or the double rotation motor spindle is often used as the spindle of five-axis wood engraving machine to achieve three-dimensional sculpture. However, the rough and motor spindle may interfere with each other during machining. Hence, many small regions of rough cannot be machined. To solve this problem, an anthropomorphic double-swing-head mechanism is designed. Instead of motor spindle, the designed mechanism is used as spindle of five-axis wood engraving machine. The level of automation and machining scope of the machine are improved. The workload of subsequent artificial modification is reduced. Then, the machining efficiency and quality of wood products are enhanced, and their production costs are reduced.

Root wilt disease (RWD) is a debilitating malady of coconut in India that is caused by phytoplasma. In RWD affected palms, leaf rot disease (LRD) is commonly superimposed. The LRD is due to fungi and this leaf rot phase forms an integral part of RWD complex. Control of LRD is important as it severely disfigures the palm and brings about rapid deterioration in its health and productivity. Control trial involving Phytosanitation of young leaves, pouring of broad spectrum - systemic fungicide, Contaf 5 E (Hexaconazole 5% EC) into the axil of spindle leaf besides a number of other measures was conducted to study their ameliorating effect on LRD. Prophylactic control trial, especially with the broad-spectrum fungicides was also conducted. Pouring of Contaf into the axil of spindles along with phytosanitory measures on the spindle and other young leaves significantly reduced the incidence of LRD in newly emerging spindles effecting cure. Application of the fungicide on RWD palms prior to the onset of LRD, offered prophylactic protection to emerging leaves against LRD. Relevance of practising integrated control measures, cure of LRD at an early stage itself, the need for strict adoption of crop management technology etc. for effective disease control are highlighted here.

A threaded gear in machine tools is a mechanical actuator that converts rotary motion into linear one of the machine axis using a recirculating ball-nut. It provides positioning accuracy, uniform motion, silent operation, reduced wear and an increased service life. The bearing assembly of the threaded spindles should provide load transfer (cutting forces and friction forces) while maintaining high guiding accuracy. Due to a high number of the threaded spindle revolutions and the presence of tension in the bearing and a high axial force originating from the cutting and friction forces, the increased heat load due to friction in the bearings is normally expected. For this reason, this paper presents a thermal analysis of the bearing assembly of the threaded spindle which is realized via an axial ball bearing with angular contact of the ZKLN type, produced by the German manufacturer Schaeffler (INA); in other words, a numerical thermal analysis has been performed.

Microtubule dynamics are influenced by interactions of microtubules with cellular factors and by changes in the primary sequence of the tubulin molecule. Mutations of yeast β-tubulin C354, which is located near the binding site of some antimitotic compounds, reduce microtubule dynamicity greater than 90% in vivo and in vitro. The resulting intrinsically stable microtubules allowed us to determine which, if any, cellular processes are dependent on dynamic microtubules. The average number of cytoplasmic microtubules decreased from 3 in wild-type to 1 in mutant cells. The single microtubule effectively located the bud site before bud emergence. Although spindles were positioned near the bud neck at the onset of anaphase, the mutant cells were deficient in preanaphase spindle alignment along the mother-bud axis. Spindle microtubule dynamics and spindle elongation rates were also severely depressed in the mutants. The pattern and extent of cytoplasmic microtubule dynamics modulation through the cell cycle may reveal the minimum dynamic properties required to support growth. The ability to alter intrinsic microtubule dynamics and determine the in vivo phenotype of cells expressing the mutant tubulin provides a critical advance in assessing the dynamic requirements of an essential gene function.

Abstract The experiments were designed by testing methods and orthogonal single factor experimental design. XK5032C CNC milling machine, the equipment to achieve X-axis, Y-axis and 3-axis Z direction of the automatic feed, spindle cooling method using water-cooled. In different processing parameters (spindle speed, depth of cut and feed rate), measurement of the surface temperature of diamond tools. In the testing experiment result analysis, we conclude, the depth of cutting is the biggest influence on the surface temperature. From the orthogonal experiment data analysis, we found that, the temperature was reduced with spindle rotation but opposite with two other factors. By linear regression analysis. We get the best cutting results by choosing a large spindle rotation and a small feed rate.

Rotor axis orbit measurement of the spindle under cutting process is the important basis of cutting quality judgment and spindle fault diagnosis. In the cutting process, the non-stationary characteristics of vibration measurement signal of spindle rotor has been particularly outstanding, under such circumstances it is difficult to draw spindle rotor axis orbit accurately. To solve this problem, a new method using EEMD (Ensemble Empirical Mode Decomposition) and harmonic wavelet is put forward to realize non-stationary signal purification and rotor axis orbit feature extraction under machine tool spindle cutting process. In order to filter out the high frequency noise of the measurement, the EEMD method has been used, in addition that the characteristics of the original signal is preserved well. However the signal after EEMD filter still contains a variety of frequency components, in order to solve it, the harmonic wavelet method is used to decompose the signal into several signals according to the different frequency components, through the signal reconstruction achieve rotor axis orbit feature extraction. Using this method, the machined workpiece has been cut under the speed of 12000r/min, the vibration of spindle has been measured and processed. The experiment results show that the new method can effectively reduce the high frequency interference noise signal, and also apparently the rotor axis orbit obtained is more clearly than the original rotor axis orbit.

We have studied microtubule behavior in late anaphase and telophase spindles of PtK1 cells, using fluoresceinated tubulin (DTAF-tubulin), microinjection, and laser microbeam photobleaching. We present the results of two novel tests which add to the evidence that DTAF-tubulin closely mimics the behavior of native tubulin in vivo. (a) Microinjected DTAF-tubulin was as effective as injected native tubulin in promoting division of taxol-dependent mitotic mutant cells that had been deprived of taxol. (b) Microinjected colchicine-DTAF-tubulin complex was similar to injected colchicine-native tubulin complex in causing depolymerization of spindles. Immediately after microinjection of DTAF-tubulin into wild-type cells during late anaphase or telophase, fluorescence incorporation by microtubules was seen in chromosomal half-spindles and just behind the chromosomes, but there was no fluorescence incorporation near the middle of the interzone. Over the next few minutes, tubulin fluorescence accumulated at the center of the interzone (the equator), becoming progressively more intense. In other experiments, cells were microinjected with DTAF-tubulin at prophase and allowed to equilibrate for 30 min. Cells that had progressed to late anaphase were then photobleached to reduce the fluorescence in the central portion of the interzone. Over a period of several minutes, the only substantial redistribution of fluorescence was the appearance of a bright area at the equator of the interzone. Both the site of fluorescence incorporation and the photobleaching data suggest that tubulin adds to the elongating spindle interzone near the equator where the plus ends of the interdigitated microtubules are located. In further experiments, several dark lines were photobleached perpendicular to the pole-to-pole axis of fluorescent anaphase-telophase spindles. Time-dependent changes in the spacings between the lines indicated that the two halves of the interzone lying on opposite sides of the spindle equator moved away from one another. This shows that the interdigitated microtubules, which make up most of the interzone, can undergo antiparallel sliding. Our data support a model for anaphase B in which plus end elongation of interdigitated microtubules and antiparallel sliding contribute to chromosome separation.

Структура та об’єм роботи. У магістерську дисертацію входить вступ, 4 розділи, загальні висновки, список використаної літератури. Робота складається з 96 сторінок тексту, 21 таблиці, 43 рисунків та 10 літературних джерел. Актуальність теми. Для сучасного виробництва одним з найважливіших аспектів є час оброблення деталей, тому що це напряму має вплив на економічну складову. Для виробництва, яке виготовляє складові для протезів нижніх кінцівок, час є найголовнішою проблемою через те, що реалізація деталей відбувається за рахунок проведення тендеру у якого є певні межі часу на виконання. Тому автору необхідно було надати рекомендації для скорочення операційного часу на 20%. Мета та завдання дослідження. Проаналізувати наявний метод виготовлення деталі складної конструкції «Корпус». Проаналізувати та надати рекомендації по модернізації технологічного процесу за рахунок використання сучасного технологічного оснащення. Дослідити, оптимізувати, та впровадити в роботу нові засоби виробництва. Об’єкт дослідження – технологічний процес виготовлення модуля гомілки регульовано-з`єднувального вузла який має складну конструкцію. Предмет дослідження – скорочення операційного часу для виготовлення однієї деталі. Методи дослідження: ознайомлення та аналіз технологічного процесу, дослідження виникнення проблем технологічної системи яка використовується, аналіз каталогів провідних компаній по виробництву оснащення для отримання повної інформації використання сучасних технологій, дослідження режимів роботи обладнання для можливості зробити рекомендації по оптимізації. Наукова новизна отриманих результатів: 1. Дослідження рекомендованих режимів роботи технологічного оснащення на прикладі працюючого виробництва, оптимізація цих режимів та встановлення похибки для подальшого її використання при впроваджені нового оснащення. 2. Розробка універсального методу визначення координат осі різального інструменту під час використання редукторів з поворотним кутом осі шпинделя та його впровадження в умовах реального виробництва. Практичне значення отриманих результатів. Отримані результати були впроваджені на виробництві підприємства ТОВ «КБ «Імпульс» та в повну міру використовуються в робочому процесі. В наявності є довідка з виробництва на якому впроваджені результати роботи. Також в наявності є екземпляр експериментального дослідження для підтвердження працездатності результатів.
Structure and scope of work. The master's thesis includes an introduction, 4 sections, general conclusions, a list of used literature. The work consists of 96 pages of text, 21 tables, 43 drawings and 10 literary sources. Actuality of theme. For modern production, one of the most important aspects is the time of machining of parts, because this direction has an impact on the economic component. For the manufacturing of components for lower limb prostheses, time is the main problem because parts are sold through a tender that has certain time limits for execution. Therefore, the author had to provide recommendations for reducing operating time by 20%. The purpose and objectives of the study. To analyze the existing method of manufacturing a part of complex construction "Hull". Analyze and provide recommendations for the modernization of the technological process through the use of modern technological equipment. Investigate, optimize, and deploy new production tools. The object of study - is the technological process of manufacturing the module of the shin of the adjustable-connecting node, which has a complex design. The subject of the study- is the reduction of operating time for the manufacture of one part. Research methods: familiarization and analysis of the technological process, investigation of the problems of the technological system used, analysis of the catalogs of leading equipment manufacturing companies to obtain complete information on the use of modern technologies, the study of equipment operating modes to be able to make optimization recommendations. Scientific novelty of the obtained results: 1. Investigation of the recommended operating modes of technological equipment on the example of a working production, optimization of these modes and establishment of an error for its further use when introducing new equipment. 2. Development of a universal method for determining the coordinates of the axis of the cutting tool when using gearboxes with a rotating angle of the spindle axis and its implementation in real production. The practical significance of the results obtained. The obtained results were implemented at the production of the enterprise of DO"Impulse" Co., Ltd and are fully used in the working process. There is a production certificate on which the results of work are implemented. A copy of the experimental study is also available to confirm the workability of the results.
Структура и объем работы. В магистерскую диссертацию входить введение, 4 главы, выводы, список использованной литературы. Работа состоит из 96 страниц текста, 21 таблиц, 43 рисунков и 10 литературных источников. Актуальность темы. Для современного производства одним из важнейших аспектов есть время обработки деталей, потому что это напрямую влияет на экономическую составляющию. Для производства которое производит составляющие для протезов нижних конечностей, время является самой главной проблемою из-за того, что реализация деталей происходит за счет проведения тендера у которого есть определенные сроки времени на выполнение. Поэтому автору необходимо было предоставить рекомендации для сокращения операционного времени на 20%. Цель и задачи исследования. Проанализировать имеющийся метод изготовления детали сложной конструкции «Корпус». Проанализировать и предоставить рекомендации по модернизации технологического процесса за счет использование современного технологического оборудования. Иследовать, оптимизировать, и внедрить в работу новые средства производства. Объект исследования - технологический процесс изготовления модуля голени регулировано-соединительного узла который имеет слжную конструкцию. Предмет исследования - сокращение операционного времени для изготовления одной детали. Методы исследования: Ознакомление и анализ технологического процесса, исследования возникновение проблем технологической системы которая используется, анализ каталогов ведущих компаний по производству оснастки для получение полной информации использование современных технологий, исследования режимов работы оборудования для возможности сделать рекомендации по оптимизации. Научная новизна полученных результатов: 1. Исследование рекомендованных режимов работы технологического оборудования на примере работающего производства, оптимизация этих режимов и установления погрешности для дальнейшего ее использование при внедрении нового оснащения. 2. Разработка универсального метода определения координат оси инструмента во время использование редукторов с поворотным углом оси шпинделя и его внедрение в условиях реального производства. Практическое значение полученных результатов. Полученные результаты были внедрены на производстве предприятия ООО «КБ« Импульс »и в полную меру используются в рабочем процессе. В наличии есть справка от производства на котором внедрены результаты работы. Также в наличии имеется экземпляр экспериментального исследования для подтверждения работоспособности результатов.

The introduction of CNC machines has radically changed the manufacturing industry. Curves are as easy to cut as straight lines, complex 3-D structures are relatively easy to produce, and the number of machining steps that required human action has dramatically reduced. With the increased automation of manufacturing processes with CNC machining, considerable improvements in consistency and quality can be achieved. CNC automation reduced the frequency of errors and provided CNC operators with time to perform additional tasks. CNC automation also allows for more flexibility in the way parts are held in the manufacturing process and the time required to change the machine to produce different components. In a production environment, a series of CNC machines may be combined into one station, commonly called a “cell”, to progressively machine a part requiring several operations. CNC controller is the “brain” of a CNC machine, whereas the physical configuration of the machine tool is the “skeleton”. A thorough understanding of the physical configuration of a machine tool is always a priority for a CNC programmer as well as the CNC machine tool manufacturers. This chapter starts with a historical perspective of CNC machine tools. Two typical types of CNC machine tools (i.e. vertical and horizontal machining centres) are first discussed. Tooling systems for a CNC machine tool are integral part of a CNC system and are therefore elaborated. Also discussed are the four principal elements of a CNC machine tool. They are machine base, machine spindle, spindle drive, and slide drive. What letter should be assigned to a linear or rotary axis and what if a machine tool has two sets of linear axes? These questions are answered later in the chapter. In order for readers to better comprehend the axis and motion designations, a number of machine tool schematics are given.

Servo actuated presses can provide maximum pressing force at any slide position in the same manner that hydraulic presses do, while offering several benefits in terms of precision, energy conversion efficiency and simplicity due to their lack of hydraulic circuitry and oil. Several press builders have developed electric-spindle actuated presses; however, issues relating to multi-axis architecture have been neglected. The present study proposes an innovative method of avoiding overconstrained architecture by implementing a kinematic mechanism that connects multiple servo axes to one slide. Servo axis design is developed by creating a dynamic model of a kinematic chain composed of a servo-motor, gearbox reducer and ball screw transmission. A study of a biaxial industrial servo press prototype with non-overconstrained architecture, currently under construction, is presented as proof of concept. It is shown that such a non-overconstrained multi-axis press can be constructed from commercially available components, achieving high energy efficiency at high load with relatively simple construction.

Abstract Machine tool spindle bearings are subjected to a large range of axial and radial loads due to the machining process. Further the rotating spindle must be extremely stiff to minimize the cutting tool’s deflection. The high spindle stiffness is achieved by applying a mechanical load to the bearings, the preload. In fixed preload spindles the bearing loads tend to increase with increasing spindle speed due to thermal expansion and it is well established that these thermally induced loads can lead to premature bearing failure. A model of thermally induced bearing load in angular contact bearing spindles is developed that includes an axis-symmetric reduced order finite element model of the heat transfer and thermal expansion within the spindle’s housing and shaft and the bearing and shaft dynamics. Nodal reduction is used in the reduced order model to minimize the number of temperature states and the computational load. The reduced order model’s calculated temperature and bearing load values are shown to closely match experimentally measured values over a wide range of spindle speeds. The paper ends with a parameter variation study which predicts a dramatic decrease in the thermally induced bearing load when silicon nitride balls are substituted for steel balls.

In this paper, two different simulataneous five-axis control motions were newly proposed to identify the ten inherent deviations in universal spindle head type multi-axis machines. The ball bar was used as a measuring device. Both of the two motions were carried out bu using a single setup which was a simple extension bar. This leads to reduce non-productive time of the operator within the machine work space. Three measurments were used to estimate the ten deviations in which two measurements were extracted by means of axial direction motion and the other by tangential direction motion. By using the axial direction motion, seven deviations were estiamted in which four deviations were estiamted by means of the observation equation and simple geometric relations were used for other three. Remaining three of the ten deviations was estimated by using tangential direction motion. The validity of the proposed methodology for identifying the ten deviations inherent to universal spindle head type five-axis machining centers is confirmed by simulations.

Abstract The rotating accuracy of a machine tool spindle directly affects the roundness of machined parts. Commonly, a precision arbor and one or two probes are used to inspect the spindle axis error motion. When a reference precision arbor is not available or when the spindle error motion is in the same order of magnitude as the accuracy of the reference arbor, it is imperative to separate the roundness error of the reference arbor from the spindle error. One of the most widely used method is the three-probe method. This paper presents an exact model and in-depth error analysis for the conventional three-probe method. The results show that contrary to conventional wisdom that a precise arbor is not needed with the three-probe method, the arbor accuracy should be at least ten times better than that of the axis motion. To reduce inaccuracy in the converted axis motion and arbor contour, it is also suggested that the mounting error of the probes should be less than one-fiftieth of the size of the axis motion and the arbor size. The exact geometric model developed in this paper can also be extended to analyze the precision aspect of other methods.

Many fields of active research such as biomedical engineering, electronics, and optics have need of small metallic parts less than 1mm in size, with features measured in hundreds or tens of microns, with tolerances as small as 0.1 micron. Such parts include devices for studying the processes in the human body, devices that can be implanted in the human body, small lenses, and other small components. Micromilling is a microscale manufacturing process that can be used to produce a wide range of small parts, including those that have complex 3-dimensional contours. Micromilling is a process that is, on the surface, similar to conventional-scale milling, except for the use of tools that are around two orders of magnitude smaller than conventional endmills, and spindle speeds that are one or two orders of magnitude faster than conventional milling spindles. However, the underlying physical processes which occur in micromilling are unique due to scale effects, which occur due to the unequal scaling of physical properties between the conventional and the micro scale. One of the more recently-uncovered scale effects in micromilling is the increased ratio of tool size to feature size [1]. This scale effect causes an exacerbation of a kind of geometric error known as chord error and places a fundamental limitation on achievable feedrates within allowable machining error constraints. In this research, we hypothesize that the increase of chord error in microscale milling can be alleviated by intelligent modification of the kinematic arrangement of the micromilling machine. Currently, all 3-axis micromilling machines are constructed with a Cartesian kinematic arrangement, in which three linear axes are mounted perpendicularly. In this paper, we propose an alternate kinematic arrangement consisting of two linear axes and one rotary axis, creating a Polar kinematic arrangement. Through numerical simulation, we show that there are distinct classes of curvilinear geometries in which the Polar kinematic arrangement is preferable, and allows significant gains in allowable feedrates and reduction in chord error, while other curvilinear geometries show reduced chord error with the Cartesian arrangement.

The introduction of multi-axis CNC machining has reduced machining time and increased production rates. However, optimizing simultaneous operations to produce quality parts and prolong tool life still possesses a challenge to engineers due to the mutual interactions of two tools removing material and the amount of factors and noise in a production environment. Since there are multiple factors and the sources of error are unknown, we use a statistical approach to obtain and organize information. A design of experiment study was implemented across twelve sensor responses to optimize the spindle speed, feed rate, inner diameter (ID) depth of cut and outer diameter (OD) depth of cut for simultaneous turning and boring roughing operations. The optimal machining conditions were obtained by a response optimizer from Minitab 16 statistical software. The optimized settings result in 13% reduced cutting and 10% reduced total power consumption for a 3% increase of average power. Future studies will cross correlate different responses to reduce the number of sensors in developing a robust adaptive controller for chatter detection and tool condition monitoring.

In order to achieve high area density of HDD to 10Tbit/in2, both radial and axial direction Repeatable Run-Out (RRO) and None repeatable Run-Out (NRRO) of spindle motor in HDD should be significantly reduced. That means the high performance spindle motor is need. Currently, the spindle motor used in HDD uses a rotating shaft FDB which structure likes slender cantilever beam to support the rotor and the problem of this kind of structure is reported in [1]. This structure cannot meet HDD high TPI requirements and should be replaced by the fixed shaft FDB spindle motor and the analytical model is shown in Fig. 1. Moreover, different types of Unbalance Magnetic Pull (UMP) of the Spindle motor and induced vibration should be fully studied. In order to fully understand motor vibration behavior, a thorough theoretical derivation of motor dynamics should be carried out as they can disclose clearly the global performance of the motor. Generally, four types of UMP reported in [1]–[3] can generate the motor lateral and axis vibration and produce motor acoustic noise. Researchers have studied vibration and acoustic signals in recent years[1]–[6]. In this paper, the PMSM mathematic model has introduced and validated by 12 slots and 5 pole-pairs PM surface mounting Synchronous motor M1 simulation case study. This type of Permanent Magnetic Synchronous motor (PMSM) is using in many applications, e.g.

Conventional machining of complex parts having three-dimensional curved surfaces is performed in two steps using a five-axis machining center and a grinding machine. There is a problem with productivity. Therefore, we developed a CNC lathe to cope with high-speed machining. The newly developed CNC lathe has four axes (X1, X2, Z, C). In this machining, the tool on the X axis follows the curved surface synchronously with the rotation angle of the spindle. This cutting method enables machining of the three-dimensional curved surface. By adopting a linear motor for the X axis, high-speed reciprocal motion of the tool is realized, and the machining time has been reduced to approximately 1/30, as compared with the conventional milling process. In this operation, since high-response motion is required for the tool positioning, a certain profile error remains even if repeated control is applied using the linear scale. In the present study, for the purpose of improving the contour accuracy of a three-dimensional curved surface, we report the result of compensation between the profile measurement method of workpiece and the desired profile accuracy. After machining a three-dimensional curved surface by the developed CNC lathe, a line laser displacement sensor is used to measure the workpiece profile on the machine without removing the workpiece. The position of the machining program is measured by synchronizing the controller of the CNC lathe and the line laser displacement gauge. In addition, the desired profile accuracy is improved by compensating for the error between the desired profile accuracy and the measurement result.

A new ultrahigh speed micro-spindle has been developed for micromachining that can be used at rotational speeds as high as 500,000 rpm. Since conventional ball bearings or fluid lubricated journal bearings cannot be used at speeds beyond 300,000 rpm for any extended period of time, the new spindle uses a set of journal and thrust foil bearings. The micro-spindle was integrated with a 3-axis micro-milling machine. Cutting experiments were performed on an aluminum alloy at speeds greater than 300,000 rpm using 50 and 300 micron end-mills. The increase in rotational speed to 450,000 rpm in micro-milling of aluminum alloy allowed an increase in feed rate to nearly 800 mm/min (the maximum feed rate available by the positioning stage), thus increasing the material removal rate by more than two orders of magnitude. The dimensional accuracy of several straight cuts made at different feed rates and depths of cut was measured. Theoretical models and research on machining of industrial ceramics have shown that high-speed machining allows for smaller depths of cut by each diamond grit, thus reducing the contact forces and resulting in a reduced possibility of detrimental chipping and subsurface machining damage. Therefore, micro-grinding was performed on dental ceramics to evaluate the feasibility ultrahigh speed machining. In these studies several ceramics used for preparation of dental restorations were cut with diamond tools. The propensity for generation of machining-related damage, such as surface and subsurface microcracks, were greatly reduced by machining at ultrahigh speeds and high feed rates. Micro-machining at such high speeds, and in combination with high feed rates, has never been achieved before.

This study refers to the investigation on the critical operating condition occurring on high productivity milling machines, known as chatter. This phenomenon is generated by a self-excited vibration, associated with a loss of stability of the system, causing reduced productivity, poor surface finish and noise. This study consists of the theoretical and experimental modeling of machining chatter conditions, in order to develop a real-time monitoring system able to diagnose the occurrence of chatter in advance and to dynamically modify the cutting parameters for process optimization. A prototype NC 3-axis milling machine was ad hoc realized to accomplish this task. The machine was instrumented by a dynamometer table, and a series of accelerometer sensors were mounted in the proximity of the tool spindle and the workpiece. An analytical model was developed, taking into account the periodic cutting force arising during interrupted cutting operation in milling. The system dynamical behavior was described by means of a set of delay differential equations with periodic coefficients. The stability of this system was analyzed by the semi discretization approach based on the Floquet theory. Lobe stability charts were evaluated and associated with frequency diagrams. Two chatter types were analytically and experimentally detected: period-doubling bifurcations and secondary Hopf bifurcations. Measurement data were acquired and analyzed in the time and frequency domain. Several tests were conducted in a wide range of operating conditions, such as radial immersion, depth of cut and spindle speeds and using different tools. Results are reported showing agreement between the numerical analysis and the related experimental tests.