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•Proposes an analytical dynamic model of face-milling for spiral bevel gear.•Investigates the un-deformed chip geometry and static cutting force for spiral bevel gear.•Discusses the ...dynamic equation and semi-discretization method for chatter stability analysis.•Validates the proposed model through the simulation and experiment.
For an efficient and precise machining of spiral gear, the special face-milling process for spiral bevel gear is developed and widely used, exhibiting great difference from the general milling process in cutting machine, cutter and cutting kinematics. The un-deformed chip geometry, cutting force model and regenerating mechanism are hence complexly different, bringing great challenge to the modeling of cutting dynamics. In this regard, no relevant work can be found at present.
To overcome this problem, through fully investigating the cutting force regenerating mechanism under complicated cutting kinematics, this paper first develops an analytical cutting force prediction model by classifying the chip geometry into 6 cases, and then a simplified dynamic chip model by assuming the chip geometry cases unchanged and ignoring edge alteration.
On such basis, the model for prediction of the cutting dynamics and the chatter stability are developed and validated. Besides, the 3D stability lobe for face-milling of spiral bevel gear is presented and the cutting system tends to be stable with high cutter gear ratio and cutting speed.
Spheroidal graphite cast irons have increased ductility, tensile strength, and toughness compared to other cast irons. Additionally, it can be mentioned that choosing spheroidal graphite cast iron ...over steel material has a better machining feature. In this study, Face milling operations were carried out using GGG60 material and different inserts, feed, and depth of cut. The Taguchi method was used for the experimental design, and 27 experiments were carried out. During the experiments, a thermal camera measured the temperature from the cutting zone. Experimental results were evaluated with analysis of variance and graphics, and cutting parameters were optimized. As a result of the optimization, optimum parameters for minimum temperature, TiAlN coated insert, 300 m/min cutting speed, 0.30 mm/tooth feed rate, and 0.5 mm depth of cut were found. According to the results obtained from the study, the most influential parameter affecting the temperature was the cutting speed. In addition, the TiAlN-coated insert has been observed as the most suitable coating type for minimum temperature.
Multi-blade face milling cutters are widely used in the finish machining of mechanical parts. The cutting force in the milling process is a crucial factor that promotes the chatter of the machine ...spindles, which can be used to predict the machined surface roughness. In this paper, a novel cutting force prediction model based on non-uniform rational basis splines (NURBS) and finite element method (FEM) is proposed. Single blade cutting forces under different parameters are simulated by FEM, and a cutting force model of the single blade is established by the NURBS interpolation method. Then, combined with the tool tip motion model, the cutting force of the multi-blade face milling cutter can be predicted. To verify the correctness of the cutting force predicted by the proposed method, the common coefficient-based cutting force mathematical prediction method is utilized as benchmark for comparison with the predicted results. The accuracy is verified by comparison with experimental data. According to the collected experimental data, the proposed model is proved to be an accurate and efficient method to predict the cutting force of the multi-blade face milling cutter in the milling process.
Friction stir butt welding between A6061 and SPC270 sheets with a thickness of 1 mm was investigated in this study. The welding conditions, including the clearance, offset, welding speed, and tool ...rotation speed, were optimized and the highest tensile strength of 235.0 MPa can be achieved using the welding parameters proposed by this study. In addition, the influence of the end-face state of the SPC270 specimen was also studied. The results show that the tensile strength of the welding joints can be improved to 240.7 MPa by increasing the contact area between A6061/SPC270. Moreover, the input heat can be decreased with end-face milling of the SPC270 specimen, and a thin IMC layer with 150 nm in thickness was confirmed. In contrast, the IMC layer obtained using the welding specimen without end-face milling was 1130 nm in thickness. The temperature at the welding interface and the load added to the works during welding were also measured to reveal the influence of end-face milling.
Abstract
Most of existing researches related to ultrasonic machining on material removal mechanism are focused on single-grainultrasonic scratch and undeformed chip thickness. In this study for the ...rotary ultrasonic face milling (RUFM), two material removal modes of single and its adjacent abrasive grain with spindle speed were investigated. The impact and scratch with high-frequency vibration has been illustrated by the kinematic of multi-grain movement. We conducted the RUFM experiment to verify the proposed material removal modes. Experimental result shows that the high-frequency impact can increase surface roughness as undeformed chip thicknessdecrease, and high-frequency scratch can reduce the surface roughness as undeformed chip thickness turns up.
The increasing environmental and health concerns of conventional emulsion flood coolants have motivated the use of vegetable oil in the form of minimum quantity lubrication (MQL) in machining. This ...paper presents comparative evaluation of high oleic soybean oil (HOSO)–based MQL flow rates at 10, 30, 50, 70, and 90 ml/h with a mineral oil–based emulsion flood coolant as a benchmark in face milling of Inconel 718 using AlTiN/TiN-coated carbide inserts. Cutting forces, tool wear, and surface roughness were measured and analyzed. The results show that MQL oil flow rate at 70 ml/h gave the longest tool life comparable to that of mineral oil–based emulsion flood cooling, while 10 ml/h flow rate gave the shortest tool life. Also, 70 ml/h flow rate gave the lowest resultant cutting force among all MQL oil flow rates and conventional emulsion cooling at tool life. Increasing HOSO-based MQL flow rate improves surface roughness and reduces tool wear by providing enough thin lubrication film but also leads to an increase in chip affinity and formation of large built-up edges (BUEs) as the MQL flow rate reaches 90 ml/h. At lower HOSO-based MQL flow rate, tool wear mechanism is predominantly abrasion due to large surface friction, while at higher HOSO-based MQL flow rate, tool wear mechanism is adhesion leading to excessive BUEs. HOSO-based MQL flow rate of 70 ml/h and air pressure of 4.14 bar are recommended when face milling Inconel 718 and are demonstrated to be a potential replacement of mineral oil–based conventional emulsion flood cooling strategy for machining of difficult-to-cut metals.
In 5-axis machining, the existing tool’s axis vector optimization methods are limited since they only consider the global collision between the tool and the workpiece while aiming at the ball-nosed ...cutter. A multi-factor vector optimization method for the face milling cutter shaft is proposed to solve this problem. This method comprehensively considers machining global collision, cutting force, the angular displacement of a rotating shaft, and angular speed. An improved global collision detection method of cutter axis vector based on the NURBS surface principle is developed, and a global collision detection algorithm is employed to determine the cutter machining global collision. The relationship model between the end-milling cutter axis vector and cutting force variation is established to optimize the cutting force. In addition, an optimization model of angular displacement and velocity of the machine tool’s rotating axis is proposed based on Dijkstra optimal path algorithm. The CAM software simulation and experimental validation are conducted using a large propeller with a complex surface. The tool’s axis vector optimization algorithm is applied to the propeller results. Comparing the tool’s axis vector optimization results to those obtained without optimization, it is discovered that the surface workpiece’s machining quality has significantly increased.
In face milling processes, the surface roughness of the machined part reflects the cutting performance of face milling cutter. Surface roughness depends on different factors including feed direction, ...axial and radial run-out errors, and cutting tool geometry. In this paper, an algorithm considering the effects of static and dynamic factors on surface roughness for predicting the surface roughness is proposed. This work is focusing on straight-edged square insert. The dynamic characteristics of the milling process are also introduced. An electronic impact hammer is used to identify the dynamic parameters of the cutting system. Milling experiments are conducted to validate the prediction model. Results show that the prediction model can estimate the surface roughness of the machined parts after face milling. This paper provides an in-depth understanding of the relationship between machined surface roughness and process conditions especially for axial and radial run-out errors induced by static deformation and
Z
-axial relative displacement induced by forced vibration. The outcome of this research will lead to methodologies for cost-effective monitoring and surface roughness control.
The denoising of mechanical system is always an indispensable process in sensor signal analysis. It directly affects the result of subsequent tool state monitoring and identification. Therefore, a ...denoising framework is proposed to solve this problem. Bayesian nonparametric estimation instead of the Gaussian fitting distribution of CycleGAN can ensure the quality of denoising data to the greatest extent. The experiment of milling 42CrMo steel was carried out, and the proposed method was verified. Compared with the wavelet packet threshold, the signal-to-noise ratio (SNR) obtained by the propose model is increased by 4.71 dB on average, and RMSE ranges from 0.0210 to 0.0642. UKF-CycleGAN model has better denoising effect than other methods. The model proposed in this paper improves the accuracy of tool wear identification. At the same time, the process of selecting the parameters for denoising model by manual experience can be reduced. This provides the possibility for online denoising of sensor signals in milling process, which has certain guiding significance for tool state monitoring in machinery industry.
EN-31 is one of the difficult-to-cut steels that has applications in the manufacturing of die-casting moulds, high-strength bearing, and several heavy automobile parts. Generation of heat while ...cutting such material is the principal cause of tool wear and diminishing surface qualities of a machined part. The application of lubricant lowers the temperature of machining but the excess use of lubricant is responsible for increasing the overall cost of machining. Also, due to health and environmental concerns related to lubricant exposure, the application of the Minimum Quantity Lubrication (MQL) technique as an alternative to flood cooling is increased in recent times. In this work, an attempt is made to increase the effectiveness of the MQL technique by optimizing the parameters associated with it. The face milling experimentation on EN-31 steel is accomplished by arranging MQL parameters using Taguchi’s method-based L18 orthogonal array. CRITIC approach is exploited to determine the correlation between the tool flank wear and cutting temperature. The optimum parameter setting for tool flank wear is discovered as 150 ml/h lubricant flow rate, 40 mm spraying distance, 60 % lubricant concentration, and 45° nozzle elevation angle. A reduction of 2.10 % in the value of the flank wear is achieved at the optimal MQL parametric settings.
