Spindle Of Milling Machine Research Articles

Computational and Experimental Investigation of Thermal Generation in CNC Milling Machine Spindle Βearing with the Oil-Air Lubrication Method

This study investigates the thermal generation dynamics in the spindle unit of a CNC milling machine. The main objective is to analyze the heat transfer from the bearings to the housing during operation, using simulations and experiments. An air-oil-cooled lubrication system is employed, which enables the airflow to dissipate some of the heat produced. Before conducting the experiment, heat generation and transfer are accurately predicted. The air-oil mixture, formed by pressurized air atomizing oil droplets, is effective in cooling high-temperature regions. A spindle ER16-80SK 24k is integrated with a CNC machine for real-time data acquisition, including parameters such as spindle speed and temperature. The results show significant temperature rises in all bearings, which reach a steady state after an hour of operation. There are noticeable differences in range, from 6.1% to 43.4%, between the experimental and simulated maximum temperatures, indicating possible real factors not considered in the simulation. The environmental impacts of oil particle emission are also discussed, which require proper ventilation management during operations. This research provides valuable insight into the thermal dynamics of CNC milling machine spindles and establishes a solid basis for further research and development in this important field of machining technology.

Nonlinear Lyapunov-based control of a misaligned heteropolar magnetic bearing system

ABSTRACT The dynamic behavior of an active magnetic bearing (AMB) mounted rotor was investigated through an analytical study conducted as part of this research work. A biased AMB model was developed, in which six electromagnets were supplied with a bias current I0 , and their respective control currents. The magnetic load was obtained through a differentiated driving mode based on the virtual displacement principle. Motion equations were formulated, and simulations were performed to investigate the dynamic response of the misaligned AMB mounted on a high-speed rotor, considering rigid body motion, elastic motion, gyroscopic effect, shear deformation effect, and internal damping. Subsequently, a nonlinear novel direct Lyapunov-based controller derived from an energetic approach was applied and compared to an optimal regulator based on Hamilton-Jacobi-Bellman (HJB) equations. The Linear Quadratic Riccati (LQR) method required less energy, as expected, but the Lyapunov method was more efficient and demonstrated its ability to asymptotically control the plant instability as well as the misalignment effect. Finally, the method was applied to a milling machine spindle, and the controller was still able not only to handle the cutting forces generating disturbances but also to overcome the defect effect without any oscillation.

Prediction using multi-objective slime mould algorithm optimized support vector regression model

Different from the traditional neural network models based on empirical risk minimization principle, support vector regression (SVR) minimizes the upper limit of generalization error by the structural risk minimization principle. SVR is suitable for solving nonlinear, small-sample, high-dimensional modelling, and pattern recognition problems. However, the selection of hyperparameters of SVR can significantly affect the prediction accuracy and computational time. This paper proposes a method to optimize the SVR hyperparameters through an intelligent optimization algorithm, specifically multi-objective slime mould algorithm (MOSMA). MOSMA is a new multi-objective optimization algorithm with strong global search ability and fast convergence. The principle and calculation process of MOSMA are first described in detail. The analytical method for transforming the SVR hyperparameter optimization problem into a multi-objective problem is then presented. The process of optimizing two SVR hyperparameters (the penalty coefficient and radial basis function kernel parameter) based on MOSMA is described in steps. Meanwhile, the procedures of algorithm parameter setting, fitness function design, and population update are given. To investigate the characteristics and performance of MOSMA-SVR, two datasets are used to predict the vibration trend of the spindle of CNC milling machine in one and the maximum bending normal stress in the cutting process in the other. The performance of MOSMA-SVR is evaluated by multiple statistical indexes and compared with seven other prediction models (GA-SVR, PSO-SVR, ABC-SVR, GWO-SVR, SSA-SVR, SMA-SVR and MOWOA-SVR).

Thin Wall Manufacturing Improvement using Novel Simultaneous Double-Sided Cutter Milling Technique

Thin-walled parts are commonly used in the aerospace sector. However, there are serious machining challenges, such as deflection, deformation and vibration. The final thin-walled component machining will deteriorate the dimensional accuracy and surface quality. This is due to the vibration and deformation that occurs during flexible milling of thin-walled structures since the workpiece rigidity is lower than the cutting forces of the milling cutter. The gradual reduction of the thin-wall thickness during the end milling process results in significant deflections and deformations due to its low rigidity and low stiffness. In recent years, different approaches have been used to deal with these challenges. This paper presents a new technique for machining thin-walled parts with great accuracy, excellent flatness and straightness properties, and good productivity. The authors have developed a new milling technique using simultaneous double-sided cutter milling, in which synchronized vertical double end milling cutter finishes and machines both thin-wall surfaces simultaneously. This produces lower cutting thrust forces on the walls, as each cutting thrust force cancels out the other. The rotation of the milling machine spindle is transmitted to the double cutters by an in-house double-axis adapter. Surface errors are minimized, flatness and straightness properties are significantly improved, and the thin-wall deflection can be neglected, as shown in our results. The thin wall can be finished in only one pass, and a 50% reduction in machining time can be achieved. In addition, thin-wall flatness is improved about two to three times, compared to the conventional milling procedure.

Performance analysis of and test research on decommissioned milling machine spindle after repair

After laser cladding the spindle of the decommissioned milling machine, the surface is sprayed with nickel-based alloy powder suitable for its working hardness. After the repair, the surface microstructure is observed, with the surface hardness, residual stress, friction and wear properties tested. It is found that the repair not only improved the surface hardness but also made up for the defects of the previous external dimensional wear, and that after annealing the surface residual stress is reduced in turn. But as the depth of the thin layer increases, the overall residual stress value becomes larger. From the detection of wear scar shape, depth and area, it can be seen that under different loads, the wear time is different, the depth of the wear scar is different, and the depth of the wear scar changes as the load increases and the wear time becomes longer; but the wear depth is in the micron range. This proves that the overall performance of the remanufactured machine tool shaft parts has been improved compared to the performance of the new product, and can be used as a new product.

The Design and Implementation of Fan Chips as Cooling for Milling Process on Aluminum Alloy 5086 to Increase Tool Life

In the metal machining process, especially in the milling process, the parameters that affect the quality milling process results are cooling media because it affects the tool life used. This paper aims to determine the performance of using fan chips as the coolant in the dry milling process area. The method used is the computational fluid dynamic (CFD) method and the experimental milling process on a workpiece made from aluminum alloy 5086. In experimental testing using a variation of the milling machine spindle rotation. The simulation test results on the fluid flow character on fan chips with a protector producing a central character with a small area. In contrast, fan chips without a protector make a central character with a broader area. The wind speed data in simulation testing and experimental testing produced the same trend graph. The results of the performance of fan chips after experimented with variations in spindle rotation, cooling process on area occurs when the motor spindle rotates above 1120 Rpm on the fan chips with a protector, and the engine spindle rotates above 770 Rpm on the fan chips without a protector. The effect of fan chips on tool life affects increasing tool life by 8 minutes on installing fan chips with a protector and increasing tool life by 12 minutes on installing fan chips without a protector.

The vibration analysis of the CNC vertical milling machine spindle system considering nonlinear and nonsmooth bearing restoring force

The performance improvement of the computer numerically controlled (CNC) vertical milling machine is constrained by limited understanding of the dynamic behaviors of the spindle system. In order to study the dynamic characteristics of the CNC vertical milling machine spindle system under unbalanced force, the lumped mass method is applied to propose a novel dynamic model. In this comprehensive model, Hertz contact, radial clearance and time-varying stiffness of rolling bearings are considered. According to the contact behaviors of rolling bearings supporting the spindle, restoring force is a nonsmooth and nonlinear function of displacements and bearing radial clearance. Then, governing differential equations of the eighteen-degree-of-freedom system are derived using the Lagrange equation. In addition, the effectiveness of this dynamic model is verified by experiments. The influences of spindle speed and the bearing parameters on the vibration behaviors and stability of the spindle are analyzed by amplitude-frequency curve, bifurcation diagram, time domain waveform, spectrum diagram, trajectory and Poincaré. Moreover, we discussed how the dynamics of the spindle are affected by the eccentricity of the belt pulley, the extended length of the milling tool, and the position of the intermediate bearing set. The research results can benefit the structural design of the spindle, optimize the bearings selection, as well as improve the machining accuracy.

Thermal error modeling of CNC milling machining spindle based on an adaptive chaos particle swarm optimization algorithm

The thermal error of machine tool spindle system has become an important factor affecting machining accuracy. Measurement experiments of a 3-axis vertical milling machine spindle system were conducted to assess temperature fields and thermal errors. The fuzzy clustering and gray correlation algorithms were adopted to cluster the temperature measuring points and identify the temperature-sensitive points. Based on the adaptive chaos particle swarm optimization algorithm, thermal error models were established in the axial and radial directions for the spindle system, and the compensation effects were evaluated by the workpiece machining accuracy. The results showed that the number of temperature measuring points was reduced from 12 to 6. The residual range of measured and predicted thermal error values in the axial direction was 6.17–4.19 μm, and the modeling accuracy was 95.53%. The radial residual ranges were − 2.75–3.05 μm and − 2.10–2.15 μm, and the modeling accuracies were 90.74% and 91.10%, respectively. The model compensation effect was demonstrated remarkably in the verification experiments. The thermal error models showed high prediction precision, could improve machining accuracy and had strong engineering application value.

Modal interactions for spindle, holders, and tools

This paper describes the interaction between vibration modes associated with the machine-spindle and those associated with the holder-tool when the holder-tool combination is inserted in the milling machine spindle. It is shown that when the bending natural frequency of the holder-tool is near a machine-spindle natural frequency, there is a combined two mode frequency response (similar to a dynamic absorber) for the assembly that exhibits increased dynamic stiffness over those situations when the interaction is absent. Experimental results are provided. The variation in tool point frequency response with tool extension length is then used to calculate the corresponding stability maps. These maps are evaluated to determine the effect of interactions between machine-spindle and holder-tool modes on milling stability. Conclusions are presented.

Коррекция частоты вращения шпинделя при фрезеровании по данным численного моделирования системы: приспособление-инструмент-заготовка

Abstraсt: Machining operations are unavoidably accompanied with oscillations, which, in case of their coincidence with the natural oscillations of one of the elements of the system, can cause a resonance. The latter results in the premature failure of expensive equipment, tools and tool attachment, reduces the quality characteristics of the finished product as well as leads to rejects. Therefore, the question is raised on controlling the natural oscillation frequencies of the elements of the machine-tool system, a tool and a workpiece. Based on the finite element model of the machine-tool-device-tool-workpiece system oscillations the recommendations for choosing non-resonant rotational speeds of the milling machine spindle have been developed. The studies employed experimental, analytical, and finite element modeling methods with the use of Femap automated engineering calculation system. The experiments were carried out using Polytec measuring equipment, National Instruments LabVIEW software package, Sound and Vibration module. We have obtained the finite-element models of the device-tool-workpiece system oscillations, on the basis of which recommendations are given on setting the permissible spindle rotational speeds. The approach can find application in adjusting cutting modes when milling box-type workpieces or panel-type parts, whose workpiece geometric shape and weight differ significantly from the finished part ones.

One Abstraction Method for Displacement Response in the Sweep-Frequency Testing of Rotating Spindle

ion Method for Displacement Response in the Sweep-Frequency Testing of Rotating Spindle Guo Yuzhu1,a*, Chen Tianning1,b, Wang Xiaopeng1,c and Xu Yanfei11 State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, 710049 Xi’an, China aguoyuzhu@126.com, btnchen@mail.xjtu.edu.cn, cxpwang@mail.xjtu.edu.cn Keywords: Rotating spindle; Sweep-frequency measurement; Error separation. Abstract. In the measurement of motorized spindle dynamic performance, the non-contact sweep-frequency excitation is adopted to obtain the displacement response of spindle rotor under high speed rotating. Due to the shape error at measurement section, eccentric error and random vibration, the illusory signals is introduced to the practical measured signal, which makes it difficult to analyze the displacement response. To effectively separate the error, a new method combining template signal and slip filtering is presented. After analyzing the characteristics of displacement response and illusory signals in time-frequency domain, the template signal constructed by the non-superposing portions between response and error is employed to eliminate the error in superposing portions. And a band-pass filter which can slip in time-frequency domain is employed to eliminate the other error. A spindle of CNC milling machine is tested at 7000 r/min, and the analysis result shows that the displacement response can be abstracted successfully from the original signal measured by rotating spindle.

Analysis of the mechanical dynamic performance for the CNC machine spindle remanufacturing

ABSTRACTIn this paper, the CNC machine spindle after remanufacturing is researched as a object on the multi-constrained state. At first, it is established a three-dimensional simulation model for a CNC milling machine spindle system in theory, secondly this article uses the CATIA software of finite element analysis function to analysis the remanufacturing of machine spindle system static. Through dynamic analysis function of CATIA software, it has carried on the dynamic simulation of slender shaft, get the remanufacturing dynamic characteristic parameters of machine spindle system. Modal analysis was carried out on the remanufacturing machine tool spindle system, get the machine spindle system modal frequency and vibration mode in different order number. The paper contrast theoretical analysis and the modal analysis, validate the correctness of theoretical analysis.

Estimation of the in-plane vibrations of a rotating spindle, using out-of-plane laser vibrometry measurements

A method for estimating the in-plane vibrations of a rotating spindle using out-of-plane laser vibrometry measurements is described. This method enables the possibility to obtain the two orthogonal radial vibration components of a rotating spindle. The method uses the fact that the laser vibrometer signal is a total surface velocity of the measurement point in the laser direction.Measurements are conducted on a rotating milling machine spindle. The spindle is excited in a controlled manner by an active magnetic bearing and the response is measured by laser vibrometer in one of the two orthogonal directions and inductive displacement sensors in two orthogonal directions simultaneously. The work shows how the laser vibrometry crosstalk can be used for resolving the in-plane vibration component, that is the vibrations in the laser vibrometer cross direction. The result is compared to independent measurement signals from the displacement sensors.The measurement method can be used for vibration measurements on rotating parts, for example, where there is lack of space for orthogonal measurements.

Design and analysis of spindle head for micro milling machine

We are well known of phrase “World is becoming so smaller” i.e. the current era is of micro parts and the sizes of the parts are reducing day by day. On the other hand these small parts required to be manufactured with great accuracy and high surface finish. Usually these complex, three dimensional shapes are manufactured with the special milling machine called micro milling. The problems associated with micro milling are, increase in spindle run out & its vibrations with increase in speed. Also, critical design of high speed bearings & drive system adds to its complex nature. Thus challenge lies with controlling the stated noise factors. It is proposed to have friction disc drive for micro milling machine spindle. In the present work the emphasis is laid on controlling the spindle run out by proper design. Also, analysis of spindle by FEM (Finite element method) is undertaken. The results obtained for designed spindle under stipulated conditions of cutting force (3-7 N) are motivating. The maximum run out for spindle in this case found to be 20μ & minimum is 13μ. The analysis carried out takes in to account the linear as well as non linear aids. The speed adopted in current case is in the range of 1600 to 9600 rad/sec. However it is recommended to use speed in the range of 4000 to 4800 rad/sec. the stiffness of air bearing is kept in the range of 8×10 4 to 8.8×10 5 N/m. it is recommended to keep stiffness of air bearing between 5.2×10 5 to 7.2×10 5 . The diameter of tool shank must be in the range of 2.5 to 3.2mm. Length of tool shank is to be kept in between 38 to 50mm & the tool with young’s 6.8×10 11 N/m 2 must be used so as to have minimum spindle run out.

Performance Evaluation of Machine Tool Probe for In-process Inspection of 2D and 3D Geometries

Abstract Dimensional measurement of work piece in between the manufacturing process is an essential method to achieve the precision components. The machine tool probing system can measure machined features of work piece placed on the machine table after partial or final machining operation. The in-process machine tool probing system is helpful in minimising the lead time of component by eliminating the unloading time on the machine and loading and inspection time on the measuring instrument. It also improve the part quality through process control. In this research, the component inspection is performed by optical machine tool probe when position into the spindle of CNC milling machine. The relative movement between the probe and job are programmed by developing a CNC part program. The probe touches the machined surface as per the program codes and the optical machine interface (Transceiver) receives signal data through infrared optical waves and these signals transformed into the CNC controller through wired network. The CNC controller displays the data points on the screen. These data points were transferred into CAD system for generating lines, curves and thereafter surfaces and these generated surfaces were analysed against CAD model of the designed component for dimensional evaluation. The results obtained by this machine tool probe for 2D features are validated through digital height gauge and 3D features are by coordinate measuring machine (CMM). It was found that the optical probing system can be employed during in-process inspection and can be replaced measurement by costly CMMs for inspection of 3D features of low precision components.

Phase correction for frequency response function measurements

Abstract In modal testing, an impulse is often used to excite the structure and a linear transducer is used to measure the response. For these impact tests, two signals are measured: the impulsive force and the vibration response. Any lack of synchronization in the time domain acquisition of the two signals results in a frequency-dependent phase error in the frequency response function, or FRF. However, knowledge of the time delay may be used to correct the corresponding phase error. In this research, tests were conducted to measure the frequency-dependent phase error for a capacitive sensor and a frequency domain technique is proposed to correct the FRF. The method was validated using an FRF measurement of a cylindrical artifact mounted in a milling machine spindle.

TH6213 CNC Boring and Milling Machine Spindle System Thermal Equilibrium Analysis

The thermal deformation of machine tools has a great influence on machining accuracy. Studied on thermal effects of TH6213 CNC boring and milling machine spindle system, bearing heat grows with load and boring spindle extending length, and brings about a changeable temperature difference, which is hard to reduce. A subsection cooling scheme was proposed to reduce the spindle system temperature as well as the temperature difference to reduce the thermal deformation effects.

Dynamics Analysis of Milling Machine Spindle

The paper takes the numerical control milling machine xk8140 as the research object. The machine tools spindle system digital model is established in UG. The spindle systems natural frequency is obtained throng dynamics analysis of milling machine spindle under specific working conditions, as well as the relational of vibration and error in harmony response situation. In view of the result the rational appraisal to the spindle system structure rationality is made. Accordingly, the irrational causes removed, that noise increasing, processing quality reducing obviously and so on attribute to the irrational structure of the spindle system machine tools when the spindle rotational speed achieve 4000rpm or higher.

Development of Parrametric Modeling for the Spindle of NC Milling Machine Based on ANSYS

With the development of manufacturing technology, modern CNC machine tools are greatly improved in machine processing range, dynamic performance, the processing precision and reliability with the help of the modern design technology, process intensification and the new function part. The research object is mainly based on a CNC milling machine spindle system, using ANSYS software for the spindle of machine tool modeling, and then puting the design parameters into the already built parameterized model. It is known that the spindle is in high speed operation of the deformation and vibration characteristics by analyzing, the some unreasonable parameters were improved using some assumptions, so that the spindle is more stable and reliable in high speed and super high speed running dynamic performance, thus improving the processing precision fastly. Through the model analysis, this step is simplified in manufacturing prototype, thereby simplifying the cost, shorten the design cycle.

A New Approach to CNC Milling Machine Spindle Design

During the technological development, some equipments remain mostly the first days design besides most of others change repeatedly. CNC Milling machines spindle design is one of these which remains mostly the same. With the existing design, in order to obtain the desired torque for metal milling process, the body of the spindle is made huge and heavy which causes the whole machine body to be constructed huge and heavy. In this study a new approach to CNC Milling Machine Spindle Design is made. The design changes the hob to be held indirectly instead of to be held directly at the lower end of the spindle. The huge spindle motor is fixed to the ceiling over the machine and a flexible steel rope is used to transfer the rotational motion. At the end of the steel rope, a planetary gearbox is fixed which is also fixed to the mobile part of the CNC construction. By this way, the required torque is obtained just at the milling process takes place and the motion transmission parts can be made light in weight like the whole construction would be made.