Spindle Revolution Research Articles

APPLICATION OF THE MONTE CARLO METHOD FOR THE OPTIMIZATION OF MATHEMATICAL MODEL OF SURFACE ROUGHNESS

<p style="text-align: justify;">This paper shows optimization by using the Monte Carlo method, the mathematical model of roughness, or the mean arithmetic deviation of the profile. Optimization means finding the best of all possible solutions. According to the experiment plan, an experiment<br />was previously performed. Based on the results of the experiment and the plan matrix, the coefficients of the mathematical model were determined. An adequate and nonlinear mathematical model, suitable for optimization, gives the dependence of the mean arithmetic deviation of the profile from the number of main spindle revolutions, feed rate, tool diameter and cutting depth. The Monte Carlo method simulates action or proces by performing number of fictitious experiments using random numbers. The application of Monte Carlo method in optimization is not original. However, using MS Excel as a technique shown in this paper is original, reliable and simple. The disadvantage is imprecision. It is recommended to use Monte Carlo method as a control method in relation to some other method.</p>

Mechanism to suppress regenerative chatter vibration due to the effect of air-cutting and multiple regeneration during low frequency vibration cutting

Recently, the application of low frequency vibration has been attempted in the turning process. The tool is vibrated in the feed direction by numerical control to break up long continuous chips that adversely affect the surface quality and tool wear, etc., by generating a duration of cutting edge leaving workpiece. In order to achieve higher machining efficiency in vibration cutting, however, it is necessary to focus on chatter stability. When chattering occurs, a higher frequency chatter vibration is superimposed on the low-frequency tool vibration caused by the feed motion of the servo drive. However, the chatter amplitude decreases due to system damping, because the cutting force does not act in the air-cutting section of vibration cutting. In addition, tool displacement is regenerated not only before one spindle rotation, but also before two or more rotations in vibration cutting. Therefore, the application of low frequency vibration has an important influence on the chatter stability. The purpose of this study is to reveal the detailed effects of vibration conditions on the stability limit, and identify the vibration conditions that achieve high chatter stability. We consider the effect of the air-cutting and multi-rotation delayed regeneration described above, in which chatter displacement occurring more than two spindle rotations before is regenerated, and analyze regenerative chatter vibration during vibration cutting in the frequency domain. In this study, the phase difference φ of tool motion in vibration cutting is focused as an important vibration condition parameter that affects the stability limit. In the conventional condition (φ = π), the air-cutting ratio is limited to a relatively low value, and only the dynamic displacements before one and two spindle revolutions are regenerated. On the other hand, setting φ appropriately under the condition φ≠π, the air-cutting ratio is increased. Furthermore, the dynamic displacement is regenerated not only before one and two spindle rotations but also before three or more spindle rotations. These results indicate that proper setting of the phase difference φ is effective in suppressing regenerative chatter vibration due to the effects of both the air-cutting phenomenon and multi-rotation delay. Finally, cutting experiments show that the phase difference φ specified by the analysis was effective in suppressing chatter vibration. In summary, the application of low frequency vibration with an appropriately set phase difference φ is an effective strategy for suppressing chatter vibration without reducing the material removal rate in the turning process.

Surface roughness analysis of high speed milling in grooving

High-speed milling is a machining method with a low cutting depth, high feed rate, high cutting speed and high spindle speed. It also has the advantages of small thermal deformation, low cutting force resistance, and low tool wear. In this experiment, the cutting of S45C medium carbon steel was tested. This study used four factors in Taguchi’s experimental design regulations, and each factor used three level configurations. An L9 (34) orthogonal table was used to configure the factors and levels. In this study, experiments were conducted on CNC machine tools to explore the difference in the surface roughness of a work piece after cutting with different cutting parameters. It was found that high-speed cutting could indeed obtain quite excellent surfaces. After the experiment, the Taguchi method was analyzed and the results were obtained under different cutting parameters. The experiment is to use milling parameters as variables to analyze the surface roughness, and then the results were analyzed to derive the relationship between the milling parameters and surface roughness. When the feed per edge of the end mill was larger and the number of spindle revolutions was slower, the surface roughness value was larger. The process parameter combination with the best surface quality was 0.1 mm/tooth per edge and a cutting speed of 550 m/min. The best surface roughness of the work piece could be obtained under the combination of a cutting depth of 0.2 mm and a spindle speed 6500 rpm.

Database for Optimal Selection of Cutting Conditions, Forces and Power Consumption in Machining Processes (Dept.M)

Selecting the cutting data (cutting speed, feed, depth of cut) and the proper cutting tools play a significant role in achieving minimum production time, consistent quality and in controlling the overall cost of manufacturing. However, searching for a proper tool/insert-job combination calls for a huge amount of data and an extensive knowledge base and may take a long time and effort if it is done manually. In this paper, a software has been designed and established using Microsoft Visual Basic.Net and SQL server to store all different types of tool grades with their available cutting data, inserts, and tool holders for all materials and some machining operations (turning, drilling and milling) in a database. The software is capable of selecting the suitable cutting data, tool grade, insert and tool holders for each operation in two cases. The first case uses the maximum cutting speed of the tool grade (minimum tool life) while the second case uses the minimum cutting speed (maximum tool life). In the two cases, the software considers the constraints of power, efficiency, and maximum spindle revolution of the machine as well as the required surface roughness of the workpiece. The software is capable of calculating the machining time, intermittent time, force, torque, power, spindle revolution and total production time and cost for each operation. In addition, the workpiece material, required operations, cutting data, force, torque, power, the suitable tool grade and its manufacturer, insert and tool holder are displayed in a single report as a process sheet. Another report can be used to show the total production time and the total cost. A case study has been done to test the proposed software and it was found that about 34% of the total production time could be saved by using the maximum cutting speed, compared with the minimum cutting speed. On the other hand, about 28% of the total production cost could be saved by using the minimum cutting speed, compared with the minimum cutting speed.

Quality assurance in the process of machining of parts made of heat-resistant alloys with the help of abrasive electrochemical grinding

For the purpose of efficient treatment of heat-resistant alloys, an abrasive electrochemical part grinding method is proposed using an advanced abrasive wheel cleaning method by means of abrasive wheel contamination assessment. The process was researched and it was revealed that a parameter which is a ratio of cutting force against the ECT (electrochemical treatment) phase duration within one round of spindle revolution is versatile, which means it does not dependent on the EDM electrode cutting feed rate, the depth of treatment, and is an independent value.

Online chatter detection in milling process based on VMD and multiscale entropy

Chatter is a kind of self-excited vibration, which always has a negative impact on production efficiency. In this paper, a novel online chatter detection method for milling processes is proposed. In this method, firstly, the spindle revolution period component is extracted by angular synchronous averaging (ASA) the vibration signals generated in different cutting conditions. Then, the residual part related to chatter is calculated by subtracting the periodic component. Subsequently, the filtered signal is decomposed into a set of intrinsic mode functions (IMFs) using variational mode decomposition (VMD) to obtain chatter information. Finally, the multiscale permutation entropy (MPE) and multiscale power spectral entropy (MPSE) of the selected IMFs are calculated, and Laplacian score (LS) for feature selection is applied to select the optimal sensitive scale features with generalization. Online chatter detection based on selected sensitive scale features by splitting signal up into overlapping frames in milling process. The analysis results show that the proposed method can effectively detect the chatter under stable cutting conditions and variable cutting conditions.

A novel online chatter detection method in milling process based on multiscale entropy and gradient tree boosting

Abstract In the milling process, chatter, which results in poor surface quality, dimensional errors, reduced cutter and machine life, is one of the main limitations on performance. In this paper, a novel method of online chatter detection for milling processes is developed. In this method, first, the spindle revolution period component is obtained via angular synchronous averaging (ASA). Then, the residual part related to chatter information is calculated by subtracting the periodic component. Secondly, the multiscale permutation entropy (MPE) and multiscale power spectral entropy (MPSE) of the residual part are calculated, and the Laplacian score (LS) for feature selection is applied to select the optimal sensitive scale features with generalization. Online chatter detection that is based on selected sensitive scale features by splitting signal up into (overlapping) frames in milling process. Finally, a trained gradient tree boosting (GTB) can be used to intelligent diagnosis of the chatter severity level. The analysis results show that the proposed method can effectively detect the onset of chatter under stable cutting conditions and variable cutting conditions, which is simpler and more robust than the existing methods.

Prediction of Surface Roughness for Development of Smart Milling Machine

The primary aim of manufacturing industry is to reduce manufacturing costs to the level that is as low as possible without reducing the quality of products. In the machining process of metal parts and features, smart milling process is being projected for materials removal process of both metal and non-metal with complex forms and finishing well. Measuring a quality of an efficient milling process is normally to be a base on the quality of the finished surface roughness. The affect several attributes of components of the surface roughness, such as ability to distribute the lubricant, load bearing capacity, heat transmission, light reflection, the contact causing surface friction, load bearing capacity, light reflection, coating or resisting fatigue with the aim to increase the quality of machined products and to reduce the cost of production in manufacturing. These can be achieved by determining the parameters of the metal cutting and machining process correctly and accurately. In this review paper, a comparative study is proposed in the form of regression method that is able to predict the surface roughness at several cutting parameters such as spindle revolution, cutting speed, feeding speed, depth of cut (DOC), length of cut (LOC), helix angle and nose radius of cut.

A THERMAL ANALYSIS OF THE THREADED SPINDLE BEARING ASSEMBLY IN NUMERICALLY CONTROLLED MACHINE TOOLS

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.

Pulse Efficiency and Gap Status of Rotary Ultrasonic Assisted Electrical Discharge Machining and EDM Milling

This study proposed an ultrasonic assisted (UA-EDM) and rotary ultrasonic assisted EDM (RU-EDM) spindle with ultrasonic transducer for die sinking EDM and EDM milling processes. The research includes investigation of the ultrasonic amplitude effects, spindle revolution speed, peak current, feed-rate control of EDM on the removal rate and tool wear rate for machining of SKD 61 steel. The significant factors that affect the removal efficiency and the tool wear are further verified. Especially, the fundamental studies of the gap status including gas bubble morphology and movement, debris expelling efficiency and waveform of voltage and current pulses are also investigated through experiments with a transparent observation window. Experiment results reveal that RU-EDM is superior to conventional EDM in removal rate in both sinking and milling EDM, but with the cost of a larger tool wear rate. Explanation from gap status and characteristics of the EDM pulse trains with and without rotary ultrasonic waves are compared.

Relationship between Cutting Heat and Tool Edge Temperature in End Milling of Titanium Alloy

In this study, tool edge temperature was measured by a two-color pyrometer with an optional fiber. During one revolution of spindle, the tool edge passes over the fine hole at workpiece after cutting workpiece. An optical fiber inserted into the fine hole transmits infrared ray radiated from tool edge to two detectors with different spectral sensitivities. One peak signal from each detector can be obtained by each spindle revolution. The tool edge temperature can be calculated by taking the ratio of outputs from these two detectors. The relation between cutting heat calculated from cutting force and tool edge temperature was discussed. The tool edge temperature at the same cutting heat could be compared. The wet cutting condition caused lower tool edge temperature than the others at the same cutting heat. MQL and dry showed almost same tool edge temperature. The dispersion of tool edge temperature in wet cutting is wider than that in dry cutting and MQL cutting.

Adaptive control in high-speed electric drives of a lathe feed for noncircular turning

Problems of upgrading high-speed electric drives of a lathe feed for machining such bulk and precise products of engineering industry as internal combustion engine pistons with a complex ovate-barrel-like shape are considered. It is shown that these electric drives must have astaticism with respect to chip loading to decrease shape errors. When machining the piston surface, there are both uninterrupted cutting zones and cutting zones with an interruption on part of the spindle revolution as well (for example, when passing bores by a cutter etc.). It is shown that, at the same time, it is reasonable to have the structure with an integrally proportional controller and in the case of cutting interruption with a proportional controller. A controller is proposed with the structure changed as a function of the cutting feature. Application of the adaptive controller with the variable structure in the control system of lathe feed drives for noncircular turning decreases the shape error caused by uninterrupted cutting by 5–20 times in comparison with the linear integrally proportional controller. The additional effect of the application of the adaptive control is attained due to a significant (by several times) increase in the useful life of an expensive diamond cutting tool. The control of the controller structure is effective both in systems with the software formation of controlling actions and in systems using self-training principles.

Analysis of the Face Milling Process Based on the Imitation Modelling

The results of simulation modeling of the face milling process allowed to analyze the surface finish dependence on cutting conditions. It is noted that the surface irregularity in the form of unevenness appears in face milling. Besides, the ratio of feed rate to spindle revolutions speed influences dimensions of surface roughness. The data received are experimentally confirmed.

서보모터방식 마찰용접을 이용한 TiAl 합금과 SCM440의 접합에 미치는 용접조건의 영향

Abstract In this study, characteristics of TiAl alloy and SCM440 (Cr-Mo steel) have been investigated with thevarious joining condition by servo motor type friction welder. The experimental factors of friction welder used inthis study are spindle revolution, friction speed, and distance, upset speed and distance, respectively. Servomotor type friction welder could be controlled by the level of oil pressure, and it could be performed by positioncontrol dependence of electrical energy. Mechanical properties and morphology of welded interface were charac-terized by various joining condition. This aroused due to the bond strength dependence on friction heat and sizeof the heat affected zone. Therefore, it is necessary to have enough friction heat and decreased heat affectedzone for good friction welding between dissimilar metals. An optimum bond was obtained between TiAl alloy andSCM440 by controlling friction speed and distance. At the spindle revolution 4,000 rpm, friction speed 120 mm/min, friction distance 15 mm, the bond strength was found to be 312 MPa.(Received February 11, 2016; Revised February 17, 2016; Accepted February 25, 2016)Key words : TiAl alloy, SCM440, Servo-motor type friction welding, Joining factors

Hydro-abrasive Disintegration of Alloy Monel K-500 – the Influence of Technological and Abrasive Factors on the Surface Quality

The paper deals with the hydroabrasive disintegration of rotating workpiece of alloy Monel K-500. The aim of the paper is to analyze the impact of technological factors (traverse speed of cutting head, spindle revolution) and abrasive factors (abrasive mass flow rate, MESH) on the surface quality and material removal rate using planning experiment. Roughness parameters (Ra, Rq, Rz) were measured by optical profilometer and analyzed using mathematical-statistic methods. The presented results demonstrate, that the main influence on the final surface quality represent traverse speed of cutting head and abrasive mass flow rate. The influence of spindle speed and MESH of abrasive particles was not strong. The traverse speed of cutting head and abrasive mass flow rate influenced the material removal rate the most.

Tangential turning of Incoloy alloy 925 using abrasive water jet technology

The paper deals with tangential abrasive water jet (AWJ) turning of Incoloy alloy 925. The aim of the experiment was to analyze the impact of the AWJ traverse speed (1.5–9 mm/min) on the surface quality in terms of micro-structure formed on the created surface. The water pressure was set to 400 MPa and the spindle revolution to 34 rpm. Australian garnet (MESH 80) was used as an abrasive component. The surfaces were visualized and qualitatively described using a laser confocal microscope. Basic roughness parameters of the surfaces (Ra, Rq, Rz) were measured using an optical profilometer. The presented experimental results demonstrate that the technology of abrasive water jet turning is an appropriate tool for rough machining of difficult-to-machine materials.

SM45C 중실축의 마찰용접 기계적 특성에 관한 연구

AbstractIn the presented study, SM45C carbon steel parts were joined by friction welding. The welding process was carried out under optimized conditions using statistical approach. The study of SM45C is conducted with various combinations of process parameters. Parameter optimization, microstructure and mechanical property correlation are the major contribution of the study. The welded joints were produced by varying spindle revolution speed, friction pressure, upset pressure and burn-off length. Tension tests were applied to welded parts to obtain the strength of the joints. Fracturs properties were additionally obtained experimentally under fluctuated tensile loads. Microstructures using microphotographs were examined in the weld interface and weld region and heat affected zone and base metal and flash zone of welded parts. Finally, Hardness variations in welding zone and base metal were also obtained. Through these tests, the optimum conditions of parameters for ∅20 SM45C in friction welding were obtained when the friction spindle revolution was 1,950 rpm, the friction pressures was 30 MPs, upset pressures was 50 MPs.

Tool Wear, Hole Characteristics, and Manufacturing Tolerance in Alumina Ceramic Microdrilling Process

Microdrilling is an essential process in the electronics, aviation, and semiconductor industries. Since microdrills have low rigidness and a high aspect ratio, precise drilling parameters are required to prevent tool breakage from excessive thrust force or torque. This study implements thousand-micron grade microdrilling experiments in alumina ceramic to investigate the effects of drilling parameters on hole characteristics. Because ceramic has poor machinability, the holes must be fabricated by peck-drilling at shallow depths and continuous cooling. The drilling parameters analyzed included the spindle revolution speed, drill feed rate, peck-drilling return distance, and centering drill depth. Characteristics of the hole diameter and roundness were measured by a computer numerical control (CNC) image measurement device. The optimal parameters combination was derived by a two-stage Taguchi's experiment. This study also observes tool wear on chisel edge and generalizes manufacturing tolerance to obtain stable quality characteristics. This article presents valuable process data for thousand-micron grade microholes drilled in sintered alumina ceramic.

Modeling, measurement, and evaluation of spindle radial errors in a miniaturized machine tool

Miniaturized machine tools have been established as a promising technology for machining the miniature components in wider range of materials. Spindle of a miniaturized machine tool needs to provide extremely high rotational speed, while maintaining the accuracy. In this work, a capacitive sensor-based measurement technique is followed for assessing radial errors of a miniaturized machine tool spindle. Accuracy of spindle error measurement is affected by inherent error sources such as sensor offset, thermal drift of spindle, centering error, and form error of the target surface installed in the spindle. In the present work, a model-based curve-fitting method is proposed for accurate interpretation and analysis of spindle error measurement data in time domain. Experimental results of the proposed method are presented and compared with the commonly followed discrete Fourier transform-based frequency domain-filtering method. Proposed method provides higher resolution for the estimation of fundamental frequency of spindle error data. Synchronous and asynchronous radial error values are evaluated in accordance with ANSI/ASME B89.3.4M [9] standard at various spindle speeds and number of spindle revolutions. It is found that the spindle speed and number of spindle revolutions does not have much influence on synchronous radial error of the spindle. On the other hand, asynchronous radial error motion exhibits a significant speed-dependant behavior with respect to the number of spindle revolutions.

Role of component configuration in evaluation of accelerated rolling contact fatigue of ball bearings

Abstract Four-ball testers are widely used for determining the rolling contact fatigue life of bearing components. The tester simulates the rolling conditions in the bearing where the upper ball and the cup simulate the inner and outer rings, respectively, and the planetary balls represent the rolling elements in the bearing. However, in many studies the upper ball is utilized as the ball whose rolling contact fatigue (RCF) life is investigated, mainly to speed up the fatigue process. In this paper, a four-ball tester is used to study the effect of ball configuration, i.e. upper ball versus the planetary ball, on the RCF life. It was observed that the 52100-steel upper ball's L 10 life is 7.4 times shorter than that of 52100-steel lower planetary balls. For M50 tool steel, the L 10 life of the upper ball was 5.9 times shorter than that of the lower planetary ball. The lesser number of stress cycles per revolution of tester's spindle and the skid of lower balls resulting in rolling on multiple rolling tracks are the contributing factors to the longer RCF life of planetary balls.