Spindle Speed Variation Research Articles

The Effect of Process Parameters on the Energy Consumption in Single Point Incremental Forming

Recently, environmental and sustainability concerns have gathered considerable attention in the academic world. Some contributions have been made in this field, but for manufacturing processes, and specially for forming processes this concern has just begun. For this reason, in the present work the influence of the variation of several process parameters in Single Point Incremental Sheet forming has been carried out. Thus, a campaign of experiments with its corresponding statistical analysis has been done. The calculation of CO2 emissions for the ISF-formed part, under the Spanish framework, has been also carried out. Spindle speed variation is the most significant parameter, followed by the material and incremental step. From results, an improvement of the combination of process parameters in order to minimize energy consumption will be possible.

Application of spindle speed variation for chatter suppression in turning

In the present paper the chatter instability of variable speed machining is studied. Though, there exist numerical methods for the computation of the stability lobes for variable speed machining, especially in turning processes the potential of an active spindle speed variation for chatter suppression is mostly unexploited. In the case of a slowly time-varying spindle speed, which is practicable on a real machine tool, the stability behavior with a time-varying spindle speed is connected to the stability behavior with constant spindle speeds. This so-called frozen time approximation helps to understand the stabilizing mechanism of turning with spindle speed variation. Strategies for tuning the parameters of the speed variation for an optimal stabilization are developed. The results presented here are useful for a practical implementation of variable speed machining to increase the productivity without any negative effect due to the variation of the spindle speed.

Stability analysis for variable spindle speed milling with helix angle using an improved semi-discretization method

Chatter in milling is still a main obstacle in surface finish, machining accuracy and tool life. Its prediction and avoidance are challenging subjects in the machining field. In this paper, an improved semi-discretization method is proposed to predict variable spindle speed milling with helix angle. Based on tool geometry and machining theory, the cutting region is divided into five different cases to calculate the cutting force. The influences of radial immersion rate and modulation parameters relative to variable spindle speed milling are explored. By comparison with constant spindle speed, the simulation results show that the variable spindle speed scheme can obtain a larger range of stability. In short, the helix angle and variable spindle speed play an important role in the stability of milling process.

Suppressing Chatter in a Plunge Grinding Process: Application of Variable Rotational Speed of Workpiece

This paper investigates the regenerative chatter in a plunge grinding process. The effect of the contact force on the onset of chatter vibration is clarified by a proposed continuation algorithm, and the boundary for the chatter-free region in which the grinding process is stable is obtained. By varying the rotational speed of the workpiece continuously, the chatter vibration with the values of the system parameters being near the boundary is suppressed, namely, the chatter-free region is expanded by this spindle speed variation control strategy.

Intermittency and multiscale dynamics in milling of fiber reinforced composites

We have analyzed the variations in cutting force during milling of a fiber-reinforced composite material. In particular, we have investigated the multiscale dynamics of the cutting force measured at different spindle speeds using multifractals and wavelets. The multifractal analysis revealed the changes in complexity with varying spindle speeds. The wavelet analysis identified the coexistence of important periodicities related to the natural frequency of the system and its multiple harmonics. Their nonlinear superposition leads to the specific intermittent behavior. The workpiece used in the experiment was prepared from an epoxy-polymer matrix composite reinforced by carbon fibers.

Stability predictions of milling with variable spindle speed using an improved semi-discretization method

During milling, mechanical vibrations known as “chatter” result in lessened productivity, poorer product surface finish, and decreased cutting life of the tool. Thus, it is desirable to predict and avoid the onset of this instability. In this paper, we propose an improved semi-discretization method, based on the Floquet theory, to predict the sinusoidal spindle speed modulation of milling processes. Compared with the non-improved semi-discretization method, the accuracy and efficiency of the proposed algorithm are verified. In addition, stability is predicted using benchmark examples. The stability charts for variable spindle speed milling are compared with those for constant spindle speed milling. The results show that chatter can be effectively suppressed by varying the spindle speed.

Theoretical modelling of slurry erosive wear testing of HVOF thermally sprayed Inconel-Titania coatings

Material loss due to slurry erosion is a serious problem in many industrial applications like hydraulic turbines, slurry pumps, pipe lines, etc. where the ideal choice of engineering materials is a real challenge. Lightweight aluminum alloys are finding wi de applications in the field of aerospace automobile, defence, etc. due to improved physical, mechanical and tribology properties. HVOF (High velocity oxy fuel ) Sprayed coatings provide protection against corrosion, erosion and wear. Inconel-718 is a metallic coating which has good wear and erosion resistance. This was sprayed on to mild steel substrate and then subjected to slurry erosive wear tests. It is observed that the slurry wear rates of mild steel decreased on coating the substrate material with-718. The tests were conducted in a slurry erosive wear tester at varying spindle speeds (500 -1500rpm) at different intervals of time .The wear loss was recorded experimentallycompared with theoretical values and graphs are plotted to check accuracy. For this comparison, various parameters such as impinging particle size, velocity of solid particles, concentration of slurry bath, h ardness of mild steel, time are correlated to o btain a theoretical formulation. A non -dimensional analysis is also done to reduce the number of parameters influencing the wear rate.

Research on Technology of Variable Spindle Speed Noncircular Turning

To improve the stability and precision of noncircular manufacture process, the variable spindle speed turning is applied to noncircular turning process. The variable spindle turning system is designed. The character of variable spindle speed is analyzed. The linear servo unit available for variable speed noncircular turning process is designed. An active disturbance rejection control technique is applied to servo unit. The experiment results show that surface quality and tracking error of variable spindle speed noncircular turning are better than constant speed machining. The linear servo unit is able to track the desired trajectory of cutting tool motion.

Spindle speed variation in turning: technological effectiveness and applicability to real industrial cases

Spindle speed variation is a well-known technique to suppress regenerative machine tool vibrations especially for low spindle speeds. Although a lot of research effort was made over the years the technique is not widespread in real turning applications. In this paper, the reasons that can limit the diffusion of the spindle speed variation were investigated. Therefore, the analysis of spindle speed variation strategy was not only focused on its chatter suppression properties but also on some more general technological aspects: the surface quality of the machined components, the cutting edge-spindle bearings load and the thermal overload the electrical spindle motor is subjected to when the speed modulation is used. A time-domain numerical model of the turning process was developed and exploited to support the analysis. A lot of cutting tests were also performed both to validate the numerical model and to evaluate the effect of variable spindle speed on surface quality. Finally, some real industrial applications were analyzed focusing on thermal overload issue of the spindle motor.

Simulative Parameterization of Dead Time Variable Rotation Speed Behavior to Improve Process Stability in High Performance Cutting

A common method to improve process stability in machining operations with geometrically defined cutting edges is the variation of dead time behavior of tooth engagement, which is the most responsible influence on regenerative force amplification. In this paper a simulation model in time domain is presented, considering the effect of active and passive spindle speed variation (SSV) with regard to the calculation of process stability. The simulation approaches have been validated by experimental cutting tests on a longitudinal turning process in C45N. Beside the improvement of simulation technique, this paper points out the potential of process stabilization by high rates of SSV, even though variation frequencies and amplitudes nowadays are still limited by the drive power of machine tool systems. Additionally, a theoretical approach is presented describing the influence of process and SSV parameterization on the chip thickness modulation as well as the achievable improvement of process stability.

An Experimental Investigation of the Effects of Spindle Speed Variation on Tool Wear in Turning

Spindle Speed Variation (SSV) is a well known technique to suppress regenerative chatter vibration both in turning and milling operations but a lack of knowledge regarding the effects of non stationary cutting conditions is still limiting its diffusion in the industrial scenario. In this paper an experimental study regarding the effects of Spindle Speed Variation technique on tool wear in steel turning is presented. The experimental tool wear tests were arranged and performed following a full factorial design: the cutting speed and the cutting speed modulation were the main investigated factors. The flank wear width was the main considered process response and it was monitored continuously during wear tests up to the end of the tool life. The effects of the factors were analyzed through the Analysis of Variance (ANOVA) approach.

Tool Wear Classification Using Fuzzy Logic for Machining of Al/SiC Composite Material

Tool wear state classification has good potential to play a critical role in ensuring the dimensional accuracy of the work piece and prevention of damage to cutting tool in machining process. During machining process, tool wear is an important factor which contributes to the variation of spindle motor current, speed, feed and depth of cut. In the present work, online tool wear state detecting method with spindle motor current in turning operation for Al/SiC composite material is presented. By analyzing the effects of tool wear as well as the cutting parameters on the current signal, the models on the relationship between the current signals and the cutting parameters are established with partial design taken from experimental data and regression analysis. The fuzzy classification method is used to classify the tool wear states so as to facilitate defective tool replacement at the proper time.

Study on Online Intelligent Control of Cutting Vibration in Milling Process

To realize online and real-time suppressing vibration amplitude in milling, an open architecture intelligent controller is designed and developed, which is modular and can achieve machining parameters' online adjustment based on acceleration constraint condition. According to the idea of the velocity control, a spindle speed control model is constructed. This controller can realize both the right codes translation and assume the effective coordination and synchronization among the thread of adaptive control, interface display and interpolation and so on. A series of fuzzy control rules have been designed to reduce the vibration amplitude about stepped-weir work-piece, and some actual experiments based on acceleration constraints have been also completed. The results show the open architecture variable spindle speed controller can be used in the practical machining, and the spindle speed can realize online real-time adjustment based on the acceleration constraint condition. All these technologies can effectively suppress the cutting vibration, which protect the machine and work-piece tool system.

Timing and Written-In Errors Characterization for Bit Patterned Media

Synchronous writing in BPMR has been recognized as a crucial yet challenging issue. It has been shown that position jitter and switching field distribution can lead to spatially uncorrelated random write failures. On top of that, the spindle speed variation and other mechanical vibration may lead to accumulative phase drift during writing which causes long streams of insertion/deletion write failures. However no experiments have been conducted to quantitatively testify the later concept, nor provide precise written-in error characteristics when both phenomena are present in BPMR systems. This gap of understanding is filled by this work through spinstand and hard disk measurements and analysis. It is shown that timing inaccuracy not only introduces insertion/deletion write failures but also given rise to substantial increase of substitution (random) write errors. It also reveals that instead of the commonly accused spindle motor speed variation, timing error in BPMR based HDD may well be the result of estimation error due to limited or improperly configured timing preambles.

The Antivibration of Deeper Solt Milling System Experiment Research

The cutting vibration is a very harmful phenomenon, which destroys the surface finish and dimensional integrity of workpieces and quickens the wear of cutting tool. The cutting vibration can be suppressed or reduced by applying the variable spindle speed cutting. In order to investigate the effect of variable spindle speed parameters and cutting conditions on suppressing the vibration, the deeper slot milling tests have been conducted. The results have shown that the vibration occurring in deeper slot milling can be reduced by applying the method of variable spindle speed milling, as long as the variable speed parameters are elected suitably. The values of speed variation amplitude Δn/n0 and speed variation frequency fn of spindle speed trajectory parameter have a great effect on antivibration. Under this article test condition, the amplitude Δn/n0 of variable spindle speed is 20% and frequency fn of variable spindle speed is 0.3Hz.

Stability of systems with time-periodic delay: application to variable speed boring process

The stability of systems with fluctuating delay is studied. The aim is to demonstrate that, greater depths of cut may be achieved in a boring process, when the speed of the spindle is modulated sinusoidally instead of being kept constant. Since the variation of spindle speed is small and independent of the tool motion, by expanding the delay terms about a finite mean delay and augmenting the system, the time-dependent delay system can be written as a system of non-linear delay equations with fixed delay. The augmented system of equations is autonomous and has two pairs of pure imaginary eigenvalues without resonance. The centre-manifold and normal form methods are then used to obtain an approximate and simpler four-dimensional system. Analysis of this simpler system shows that periodic variations in the delay lead to larger stability boundaries.

A New Vari-Speed Cutting Scheme for Chatter Suppression

From the view of implementation and machine protection, this paper presents a novel scheme of programming spindle-speed variation for regenerative chatter suppression. It is based on the research of the necessary conditions of chatter, from a new perspective. Through standard test method, research are carried on the influence of the interval time and the speed variation amplitude on vibration suppression effectiveness. In this work, cutting process keeps relatively more stable without motor continuous overload, which is verified by theoretical analysis and experiments.

The Trial Research on Suppressing the Chatter by Variable Speed Milling

The vibration occurring in cutting process is a very harmful phenomenon, which destroys the surface finish and dimensional integrity of workpieces and quickens the wear of cutting tool. Cutting chatter can be suppressed or reduced by applying the method of suppressing chatter by variable speed cutting. In order to investigate the effect of variable speed parameters and cutting conditions on suppressing the chatter in face milling, the tests have been conducted.The results have shown that cutting with variable spindle speed cutting in face milling will suppress the development of chatter. If chatter occurs in cutting process, the vibration amplitude of variable speed cutting can reduce by 3-6 times lower than that of constant speed cutting, as long as the variable speed parameter are selected suitably.The values of speed variation amplitudeΔn/noand speed variation frequency fnof spindle speed trajectory parameter have great effect on suppressing chatter,Δn/no= 15- 20% andfn= 0.4 - 0.5Hz are suitable.

Application of continuous spindle speed variation for chatter avoidance in roughing milling

This paper investigates the effectiveness of the continuous spindle speed variation (CSSV) technique as a chatter-suppression strategy in the milling process. For this purpose, a two-fold study was carried out: on the one hand, a simulation analysis, and on the other, experimental tests. First, the semidiscretization method has been extended to n-mode systems in any spatial direction and modified to include simulation capabilities concerning spindle speed variation with different waveforms. A new kind of stability map for different amplitude and frequency variations is proposed in order to optimize the parameter selection when machining. Finally, the effectiveness of the CSSV technique is verified through experimental tests.

Stability Analysis of Machining with Spindle Speed Variation

In this paper the chatter stability of turning and full-immersion milling operations with spindle speed variation is studied. We present a method to calculate the stability lobes in the limit of very low and very high frequencies of the delay modulation. These approximations help to classify the results of numerically exact methods, as for example semi-discretization or multi-frequency approaches. For slowly time-varying delay, the position of the stability lobes is understandable from a simple connection between the lobes for constant and time-varying delay. Furthermore, this method can be used to estimate the efficiency of an application of spindle speed variation and helps to find optimal parameters for it.