Structure Improvement and Optimization of Gantry Milling System for Complex Boring and Milling Machining Center

To enhance the efficiency and machining precision of the TX1600G complex boring and milling machining center,a study was conducted on the structure of its gantry milling system.This study aimed to mitigate the influence of factors such as structural quality,natural frequency,and stiffness.The approach employed for this investigation involved mechanism topology optimization.To initiate this process,a finite element model of the gantry milling system structure was established.Subsequently,an objective function,comprising strain energy and modal eigenvalues,was synthesized.This objective function was optimized through multi-objective topology optimization,taking into account certain mass fraction constraints and considering various factors,including processing technology.The ultimate goal of this optimization was to create a gantry milling structure that exhibited high levels of dynamic and static stiffness,a superior natural frequency,and reduced mass.To validate the effectiveness of these topology optimization results,a comparison was made between the new and previous structures.The findings of this study serve as a valuable reference for optimizing the structure of other components within the machining center.

Optimization of micro milling electrical discharge machining of Inconel 718 by Grey-Taguchi method

The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and low working gap was investigated by the Grey-Taguchi method.The influences of peak current,pulse on-time,pulse off-time and spark gap on electrode wear（EW）,material removal rate（MRR） and working gap（WG） in the micro milling electrical discharge machining of Inconel 718 were analyzed.The experimental results show that the electrode wear decreases from 5.6×10-9 to 5.2×10-9 mm3/min,the material removal rate increases from 0.47×10-8 to 1.68×10-8 mm3/min,and the working gap decreases from 1.27 to 1.19 μm under optimal micro milling electrical discharge machining process parameters.Hence,it is clearly shown that multiple performance characteristics can be improved by using the Grey-Taguchi method.

NOVEL METHOD FOR DYNAMIC OPTIMIZATION OF STABILITY IN HIGH-SPEED MILLING SYSTEM

Considering the self-excited and forced vibrations in high-speed milling processes, a novel method for dynamic optimization of system stability is used to determine the cutting parameters and structural parameters by increasing the chatter free material removal rate （CF-MRR） and surface finish. The method is hased on the theory of the chatter stability and the semi-bandwidth of the resonant region. The objective function of the method is material removal rate（MRR）,the constraints are chatter stability and surface finish, and the optimizing variables are cutting and structural parameters. The optimization procedure is stated. The method is applied to a milling system and CF-MRR is increased 18.86%. It is shown that the influences of the chatter stability and the resonance are simultaneously considered in the dynamic optimization of the milling system for increasing CF-MRR and the surface finish.

INFLUENCE OF TOOL HELIX ANGLE ON STABILITY IN HIGH-SPEED MILLING PROCESS

An integrated dynamic model considering the influence of the helix angle is developed through dividing the cutting process into three cutting processes： uninterrupted, entry, and exit cutting processes. The semi-discretized technique is used to approximate the finite dimensional Floquet transition matrix of the dynamic control equation to determine the stability of milling process. The stability charts for helix mills are obtained. Results show that the helix angle plays an important role in the stability of milling process. The stability regions with helix angle become larger than those without helix angle. Some ＂islands＂ are presented in the stability charts, and ＂island＂ locations are determined by the relation between the axial depth of cut and the helix pitch. The ＂islands＂ are connected by the ＂bridge＂ by the effects of entry and exit cutting processes. The theoretical results are validated by milling experiments.

Modelling and simulation of high-speed milling chatter regeneration based on MATLAB

Considering the deficiency in milling process parameters selection, based on the modelling of dynamic milling force and the deduction of chatter stability limits, the chatter stability lobes simulation program for milling is developed with MAT- LAB. The simulation optimization application software of dynamics was designed using engineering simulation software Visio Basic. The chatter stability lobes for milling, which can be used as an instruction guide for the selection of process parameters, are simulated with frequency response functions （FRFs） gained by hammer test. The validation and accuracy of the simulation algorithm are verified by experiments. The simulation method has been used in a factory with an excellent application effect.

WORKPIECE LOCATING AND POST PROCESSING SYSTEMS ON 6-DOF CNC MILLING MACHINE

A conventional non-computerized numerical control （CNC） machine is updated by mounting a six degree-of-free （DOF） parallel mechanism on it, thus obtaining a new CNC one. The structure of this CNC milling machine is introduced, and the workpiece locating system and the post processing system of the cutter location （CL） data file are analyzed. The new machine has advantages of low costs, simple structure, good rigidity, and high precision. It is easy to be transformed and used to process the workpiece with a complex surface.

Engagement Angle Modeling for Multiple-circle Continuous Machining and Its Application in the Pocket Machining

The progressive cutting based on auxiliary paths is an effective machining method for the material accumulating region inside the mould pocket. But the method is commonly based on the radial depth of cut as the control parameter, further more there is no more appropriate adjustment and control approach. The end-users often fall to set the parameter correctly, which leads to excessive tool load in the process of actual machining. In order to make more reasonable control of the machining load and toolpath, an engagement angle modeling method for multiplecircle continuous machining is presented. The distribution mode of multiple circles, dynamic changing process of engagement angle, extreme and average value of engage- ment angle are carefully considered. Based on the engagement angle model, numerous application techniques for mould pocket machining are presented, involving the calculation of the milling force in multiple-circle continuous machining, and rough and finish machining path planning and load control for the material accumulating region inside the pocket, and other aspects. Simulation and actual machining experiments show that the engagement angle modeling method for multiple-circle continuous machining is correct and reliable, and the related numerous application techniques for pocket machining are feasible and effective. The proposed research contributes to the analysis and control tool load effectively and tool-path planning reasonably for the material accumulating region inside the mould pocket.

TK 5440 CNC VERTICAL BORING AND MILLING MACHINE

This machine tool produced by theQinchuan Machine Tool Worksincorporates all the commonmachining functions, and is equipped withan advanced CNC system. It can continuouslyfinish multiple working procedures such asdrilling, milling, boring, reaming and tappingwithin one clamping. Not only is it universaland efficient, but also it can machinecomplicated parts which cannot be machinedon general universal machines, such as variouskinds of precision molds, plates, disks,

Surface Roughness of Material Processing during Milling Process

To realize full automation in machining process, Computer Numerically Controlled （CNC） machine tools have been implemented during the past decades. The CNC machine tools require less operator input, provide greater improvements in productivity, and increase the quality of the machined part. End milling is the most common metal removal operation encountered. It is widely used to mate with other part in die, aerospace, automotive, and machinery design as well as in manufacturing industries. Surface roughness is an important measure of the technological quality of a product and a factor that greatly influences manufacturing cost. The quality of the surface plays a very important role in the performance of milling as a good-quality milled surface significantly improves fatigue strength, corrosion resistance, or creep life. Consequently, the desired surface roughness value is usually specified for an individual part, and specific processes are selected in order to achieve the specified finish. Purpose of the study is to develop a technique to predict a surface roughness of the part to be machined according to technological parameters. Such technique could be achieved by making mathematical model of machining. In this study as machining process the milling process is chosen, especially for end milling operation. Additionally to the study, one of the key factors, which differ from similar studies, is that as surface parameters the 2D, 3D surface parameters are used. In this study, all the surface parameters are expressed as 2D, 3D parameters. The 2D, 3D surface parameters give more precise figure of the surface; therefore it is possible to evaluate the surface parameters more precisely according to technological parameters. The result of the study, mathematical model of end-milling is achieved and qualitative analysis is maintained. Achieved model could help technologists to understand more completely the process of forming surface roughness.

Ensemble Model for Spindle Thermal Displacement Prediction of Machine Tools

Numerous factors affect the increased temperature of a machine tool, including prolonged and high-intensity usage,tool-workpiece interaction, mechanical friction, and elevated ambient temperatures, among others. Consequently,spindle thermal displacement occurs, and machining precision suffers. To prevent the errors caused by thetemperature rise of the Spindle fromaffecting the accuracy during themachining process, typically, the factory willwarm up themachine before themanufacturing process.However, if there is noway to understand the tool spindle’sthermal deformation, the machining quality will be greatly affected. In order to solve the above problem, thisstudy aims to predict the thermal displacement of the machine tool by using intelligent algorithms. In the practicalapplication, only a few temperature sensors are used to input the information into the prediction model for realtimethermal displacement prediction. This approach has greatly improved the quality of tool processing.However,each algorithm has different performances in different environments. In this study, an ensemble model is used tointegrate Long Short-TermMemory (LSTM) with Support VectorMachine (SVM). The experimental results showthat the prediction performance of LSTM-SVM is higher than that of other machine learning algorithms.

Grate-kiln pelletization of Indian hematite fines and its industrial practice

Indian hematite fines normally have a high iron grade and minor impurities; they are usually used as sinter fines for feeding into a blast furnace. In this work, the grindability properties of two kinds of Indian hematite fines and the roasting behaviors and induration characteristics of pellets made from these fines were revealed through experiments involving dry ball milling and small-scale and pilot-scale tests. In addition, the microstructures of the particles of ground India hematite fines and fired pellets were investigated using optical microscopy. On the basis of the results, a grate-kiln production line with an annual output of 1.2 Mt of oxidized pellets was established in India. This pellet plant operates stably and reliably, further confirming that preparing high-quality pellets with Indian hematite fines pretreated by dry ball milling is an industrially feasible process. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Electrode Wear Prediction in Milling Electrical Discharge Machining Based on Radial Basis Function Neural Network

Milling electrical discharge machining(EDM) enables the machining of complex cavities using cylindrical or tubular electrodes.To ensure acceptable machining accuracy the process requires some methods of compensating for electrode wear.Due to the complexity and random nature of the process,existing methods of compensating for such wear usually involve off-line prediction.This paper discusses an innovative model of electrode wear prediction for milling EDM based upon a radial basis function(RBF) network.Data gained from an orthogonal experiment were used to provide training samples for the RBF network.The model established was used to forecast the electrode wear,making it possible to calculate the real-time tool wear in the milling EDM process and,to lay the foundations for dynamic compensation of the electrode wear on-line.This paper demonstrates that by using this model prediction errors can be controlled within 8%.

Deformation Compensation of Ram Components of Super-heavy-duty CNC Floor Type Boring and Milling Machine

Ram is a very important component of super-heavy-duty computer numerical control （CNC） floor type boring-milling machine, and deformation of ram is a significant source causing errors in machining process. To compensate the deformation error of super-heavy-duty CNC floor type boring-milling machine, based on force analysis theory, the law and compensation measures of deformation of ram are researched. Based on the principle of torque （force） balance of the ram components, the formulas of compensation forces and compensation torques are derived, the relations between compensation forces （compensation torques） and the stroke distance of the ram are given. According to theoretical analysis results and the structural characteristics of super-heavy-duty CNC floor type boring and milling machine of TK6932, rods compensation, hydrostatic pressure compensation and wire rope compensation measures are taken to compensate the deformation error of ram. The experiments and computer simulation results show that the straightness of the ram at its overhanging end meets the national machinery industry standards.

Cutting force prediction for circular end milling process

A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other.

The Electrical Control System PLC Transformation of The XA6132 Milling

For the electrical control system of XA6132 milling machine circuit complexity, reliability and flexibility, high failure rate. Mitsubishi FX2N-40MR programmable controller is used to improve the performance and efficiency of the entire electrical control system by technological transformation. Mitsubishi FX2N-d0MRPLC on electrical control system transformation can expand link to the technological transformation of the similar equipments.