Geometrical optimization of the broaching tools by leveling of the cutting forces

Subtractive machining has been one of the most extensively used manufacturing methods since the industrial revolution and the broaching operation is one of the ideal and oldest machining processes for accomplishing various applications such as turbine disc fir-tree slots, non-circular internal holes and keyways. Since the broaching operation accomplished by the linear cutting motion. Although broaching process is the only machining operation in order to machine complicated profiles without using a rotary motion, it is one of the least studied one in the literature. Due to nature of the broaching process, the broach tool design is the most important step during this operation since except cutting speed there is no any other flexibility. Therefore, modeling of the cutting process and predicting critical parameters before the design stage is crucial for optimum tool design. In previous studies, an optimized model without considering constant cutting forces for broaching tool design was presented. However, developing a method to generate an optimized broach tool design based on constant cutting forces can eliminate potential problems (i.e. reduced tool life and chipping, tooth breakage, poor surface quality etc.) while decreasing its length. In this study, a method is developed in order to minimize the length of the broach, increase tool life and quality of the final part leading to reduction of whole process cost by leveling of the cutting forces in each broaching process cycle, i.e. roughing, semi-finishing and finishing

Intelligent machining methods for Ti6Al4V: a review

Digital manufacturing is a necessity to establishing a roadmap for the future manufacturing systems projected for the fourth industrial revolution. Intelligent features such as behavior prediction, decision- making abilities, and failure detection can be integrated into machining systems with computational methods and intelligent algorithms. This review reports on techniques for Ti6Al4V machining process modeling, among them numerical modeling with finite element method (FEM) and artificial intelligence- based models using artificial neural networks (ANN) and fuzzy logic (FL). These methods are intrinsically intelligent due to their ability to predict machining response variables. In the context of this review, digital image processing (DIP) emerges as a technique to analyze and quantify the machining response (digitization) in the real machining process, often used to validate and (or) introduce data in the modeling techniques enumerated above. The widespread use of these techniques in the future will be crucial for the development of the forthcoming machining systems as they provide data about the machining process, allow its interpretation and quantification in terms of useful information for process modelling and optimization, which will create machining systems less dependent on direct human intervention.publishe

Професійна технічна термінологія у галузі машинобудування

Рецензенти: Д. В. Криворучко – доктор технічних наук, доцент, професор кафедри технології машинобудування, верстатів та інструментів Сумського державного університету; В. І. Шатоха – доктор технічних наук, професор, проректор із науково-педагогічної роботи Національної металургійної академії України.Навчальний посібник є важливою формою міждисциплінарної та міжвузівської інтеграції, створений для зацікавлення студентів у якісному та поглибленому вивченні спеціальних дисциплін та професійної англійської мови, розвитку вмінь самостійної роботи і навичок при написанні та оформленні науково-дослідних робіт, активізації пізнавальної й дослідницької діяльності, стимулює наукові пошуки, обмін досвідом засобами англійської мови у галузі машинобудування. Навчальний посібник призначений для інженерно-технічних і науково-педагогічних працівників, аспірантів і студентів інженерних спеціальностей вищих навчальних закладів.Розроблено в рамках виконання проекту Темпус «Модернізація вищої інженерної освіти в Грузії, Україні та Узбекистані відповідно до технологічних викликів» (ENGITEC 530244-TEMPUS-1-2012-1-SE-TEMPUS-JPCR

An in-process, non-contact surface finish sensor for high quality components generated using diamond turning

The object of this Ph.D. project was to design and construct an in-process, non contact surface finish sensor for high quality components generated using diamond turning. For this application the instrument must have the following properties: i rapid acquisition of data. ii capability of measuring translating and or rotating surfaces. iii ruggedness for in-process use. iv insensitivity to moderate vibrations. v remoteness from the surfaces to be measured. The remoteness requirement virtually excludes the otherwise ubiquitous stylus instrument, while the rapid gathering of data from rotating surfaces excludes other profiling techniques. The above mentioned properties strongly suggest an optical method. An optical diffraction technique has been chosen, since it produces an optical Fourier Transform of the surface. This transform is produced at the speed of light, since the optical system has the property of parallel data processing, unlike a typical electronic computer. With the aid of a microprocessor various surface finish parameters can be extracted from the optical transform. These parameters are respectively the rms surface roughness, slope and wavelength. The actual sensor consists of a measuring head and a minicomputer. It fulfils the above mentioned requirements. Its only limitations are: i limited to surface finishes up to 100nm ii presence of cutting fluids has to be avoided, although certain modern lubricating fluids can be tolerated. The algorithms devised to extract the surface finish parameters from the optical transforms have initially been tested on optical spectra produced by Thwaite. Comparison of the optical roughness values and the values quoted by Thwaite show close agreement. Thwaite's values are obtained by a stylus instrument. Rqopt (um) Rqstylus (um) 0.16 0.156 0.38 0.37 0.44 0.40 In addition a computer program has been devised which simulates the optical sensor head. The input data can be obtained by a profiling instrument, or generated by a computer program. This last option enables the creation of surface profiles with "controllable" machining errors. This program can be utilised to create an atlas, which maps optical diffraction patterns versus machine-tool errors

Професійна технічна термінологія у галузі машинобудування

Рецензенти: Д. В. Криворучко – доктор технічних наук, доцент, професор кафедри технології машинобудування, верстатів та інструментів Сумського державного університету; В. І. Шатоха – доктор технічних наук, професор, проректор із науково-педагогічної роботи Національної металургійної академії України.Навчальний посібник є важливою формою міждисциплінарної та міжвузівської інтеграції, створений для зацікавлення студентів у якісному та поглибленому вивченні спеціальних дисциплін та професійної англійської мови, розвитку вмінь самостійної роботи і навичок при написанні та оформленні науково-дослідних робіт, активізації пізнавальної й дослідницької діяльності, стимулює наукові пошуки, обмін досвідом засобами англійської мови у галузі машинобудування. Навчальний посібник призначений для інженерно-технічних і науково-педагогічних працівників, аспірантів і студентів інженерних спеціальностей вищих навчальних закладів.Розроблено в рамках виконання проекту Темпус «Модернізація вищої інженерної освіти в Грузії, Україні та Узбекистані відповідно до технологічних викликів» (ENGITEC 530244-TEMPUS-1-2012-1-SE-TEMPUS-JPCR

Nanoscale measurement with pattern recognition of an ultra-precision diamond machined polar microstructure

Due to the low resolution of pattern recognition and disorganized textures of the surfaces of most natural objects observed under a microscope, computer vision technology has not been widely applied in precision positioning measurement on machine tools, which needs high resolution and accuracy. This paper presents a systematic method to solve the surface recognition problem which makes use of ultra-precision diamond machining to produce a functional and polar-coordinate surface named ‘polar microstructure’. The unique characteristic of a polar microstructure is the distinctive pattern of any locations including rotation in the global surface which provides the feasibility of achieving precise absolute positions by matching the patterns by utilizing computer vision technology. A polar microstructure which possesses orientation characteristics is also able to measure the displacement of rotation angle. A series of simulation experiments including feature point extraction, orientation detection as well as resolution of pattern recognition was conducted, and the results show that a polar microstructure can achieve a resolution of 9.35 nm which is capable of providing a novel computer vision-based nanometric precision measurement method which can be applied in positioning on machine tools in the future

An Experimental Investigation in Hard Turning of AISI 4140 Steel

There is a growing demand for new and special alloys like nickel alloys, chrome- molybdenum alloys due to their special properties like high strength, light weight, and corrosive resistance. The present work is based on the experimental investigation of chrome-molybdenum alloy to study the effect of process parameters like cutting velocity, feed, and depth of cut on the output responses like force, surface roughness, tool wear. A full factorial design with 33 lay out with total 27 numbers of runs were carried out and optimum cutting condition for all three output responses was found out using grey relational analysis method. White layer formed in a hard turned component is mainly influenced by the abrasive wear of the tool. It has immense response on the performance of product so it is necessary to find out the white layer thickness. To investigate the machined surface properties like white layer and micro-hardness, the sliced machined surface was observed under scanning electron microscope (SEM) and micro-hardness tester respectively. It has been found that the as speed increases, the thickness of white layer increases due to increase in flank wear. Finally, a thermo-mechanical 2D model using finite element method available in Deform 2D TM has been prepared to investigate the output responses like force. Further, the model has been validated comparing the results of simulation with the measured results

Hot ultrasonically assisted turning of Ti-15V3Al3Cr3Sn: experimental and numerical analysis

Titanium alloys have outstanding mechanical properties such as high hardness, a good strength-to-weight ratio, excellent fatigue properties and high corrosion resistance. However, several inherent properties including their low thermal conductivity and high chemical affinity to tool materials impairs severely their machinability with conventional machining techniques. Conventional machining of Ti-based alloys is typically characterized by low depths of cuts and relatively low feed rates, thus adversely affecting the material removal rates during the machining process. Recently, a non-conventional machining technique known as ultrasonically assisted turning (UAT) was introduced to machine modern alloys, in which low-energy, high-frequency vibration is superimposed on the movement of a cutting tool during a conventional cutting process. This novel machining technique results in a multi-fold decrease in the level of cutting forces with a concomitant improvement in surface finish of machined modern alloys. Also, since the late 20th century, machining of wear resistant materials that soften when heated has been carried out with hot machining techniques. In this work, a new hybrid machining technique called Hot Ultrasonically Assisted Turning (HUAT) is introduced for processing of a Ti-based alloy Ti-15V3Al3Cr3Sn. In this technique, UAT is combined with a traditional hot machining technique to gain combined advantages of both schemes for machining of intractable alloys. HUAT of the studied alloy was analysed experimentally and numerically to demonstrate its benefits in terms of reduction in cutting forces over a wide range of industrially relevant speed-feed combinations. Thermal evolution in the cutting process was assessed, and the obtained results were compared with FE simulations to gain knowledge of temperatures reached in the cutting zone. The developed novel turning process appeared to improve dry turning of the Ti alloy with significant reduction of average cutting forces without any substantial metallurgical changes in the workpiece material. Nano-indentation, light microscopy and SEM studies were performed to get an insight into the development of hardness in a zone near the machined surface in the workpiece. Backscatter electron microscopy was also used to evaluate the formation of α-Ti during the novel HUAT. No grain changes or α-precipitation were observed in machined workpieces in conventional and hybrid turning processes. 3D elasto-plastic thermomechanically coupled finite-element models for the orthogonal turning process were developed for conventional turning (CT), hot conventional turning (HCT), UAT and HUAT, followed by a more realistic novel 3D finite-element model for the oblique turning process. These 3D models were used to study the effects of cutting parameters (cutting speed, feed rate and depth of cut, ultrasonic vibration, ultrasonic frequency, rake angle and tool nose radius) on cutting forces, temperature in the process zone and stresses. The later model was used to analyse the effect of vibration and heat on the radial and axial components of cutting forces in HUAT, which was not possible with the developed 3D orthogonal-turning model. Comparative studies were performed with the developed CT, HCT, UAT and HUAT finite-element models and were validated by results from experiments conducted on the in-house prototype and in literature. The HUAT for the Ti-15333 was analysed experimentally and numerically to demonstrate the benefits in terms of a significant reduction in the cutting forces and improvement in surface roughness over a wide range of industrially relevant speed-feed combinations

Cutting Mechanics of the Gear Shaping Process

In the machining industry, there is a constant need to increase productivity while also maintaining dimensional tolerances and good surface quality. For many classical machining operations (e.g. milling, turning, and broaching), research has been established that is able to predict the part quality based on process parameters, workpiece material, and the machine’s dynamic characteristics. This allows process planners to design their programs virtually to maximize productivity while meeting the specified part quality. To accomplish this, it is necessary to predict the cutting forces during the machining operation. This can be done using analytical equations for a lot of operations; however, in more recent research for complicated processes (e.g. 5-axis milling, gear hobbing), this is done by calculating the cutter-workpiece engagement with geometric CAD modellers and calculating incremental cutting forces along the cutting edge. With knowledge of the cutting forces, static deflections and dynamic vibrations of the tool and workpiece can be calculated which is one of the most prominent contributors to dimensional part inaccuracies and poor surface quality in machining. The research presented in this thesis aims to achieve similar goals for the gear shaping process. Gear shaping is one of the most prominent methods of machining cylindrical gears. More specifically, it is the most prominent method for generating internal gears which are a major component in planetary gear boxes. The gear shaping process uses a modified external gear as a cutting tool which reciprocates up and down to cut the teeth in the workpiece. Simultaneously, the tool and workpiece are also rotating proportionally to their gear ratio which emulate the rolling of two gears. During the beginning of each gear shaping pass, the tool is radially fed into the workpiece until the desired depth of cut is reached. In this study, the three kinematic components (reciprocating feed, rotary feed, and radial feed) are mathematically modelled using analytical equations and experimentally verified using captured CNC signals from the controller of a Liebherr LSE500 gear shaping machine. To predict cutting forces in gear shaping, the cutter-workpiece engagement (CWE) is calculated at discrete time steps using a discrete solid modeller called ModuleWorks. From the CWE in dexel form, the two-dimensional chip geometry is reconstructed using Delaunay triangulation and alpha shape reconstruction which is then used to determine the undeformed chip area along the cutting edge. The cutting edge is discretized into nodes with varying cutting directions (tangential, feed, and radial), inclination angle, and rake angle. If engaged in cutting during a time step, each node contributes an incremental three dimensional force vector calculated with the oblique cutting force model. Using a 3-axis dynamometer, the cutting force prediction algorithm was experimentally verified on a variety of processes and gears which included an internal spur gear, external spur gear, and external helical gear. The simulated and measured force profiles correlate very closely (about 3-10% RMS error) with the most error occurring in the external helical gear case. These errors may be attributable due to rubbing of the tool which is evident through visible gouges on the finished workpiece, tool wear on the helical gear shaper, and different cutting speed than the process for which the cutting coefficients were calibrated. More experiments are needed to verify the sources of error in the helical gear case. To simulate elastic tool deflection in gear shaping, the tool’s static stiffness is estimated from impact hammer testing. Then, based on the predicted cutting force, the elastic deflection of the tool is calculated at each time step. To examine the affect of tool deflection on the final quality of the gear, a virtual gear measurement module is developed and used to predict the involute profile deviations in the virtually machined part. Simulated and measured profile deviations were compared for a one-pass external spur gear process and a two-pass external spur gear process. The simulated profile errors correlate very well with the measured profiles on the left flank of the workpiece, however additional research is needed to improve the accuracy of the model on the right flank. Furthermore, the model also serves as a basis for future research in dyamic vibrations in gear shaping. The above-mentioned algorithms have been implemented into a tool called ShapePRO (developed in C++). The software is meant for process planners to be able to simulate the gear shaping operation virtually and inspect the resulting quality of the gear. Accordingly, the user may iterate the process parameters to maximize productivity while meeting the customer’s desired gear quality

Resource selection and route generation in discrete manufacturing environment

When put to various sources, the question of which sequence of operations and machines is best for producing a particular component will often receive a wide range of answers. When the factors of optimum cutting conditions, minimum time, minimum cost, and uniform equipment utilisation are added to the equation, the range of answers becomes even more extensive. Many of these answers will be 'correct', however only one can be the best or optimum solution. When a process planner chooses a route and the accompanying machining conditions for a job, he will often rely on his experience to make the choice. Clearly, a manual generation of routes does not take all the important considerations into account. The planner may not be aware of all the factors and routes available to him. A large workshop might have hundreds of possible routes, even if he did know it all', he will never be able to go through all the routes and calculate accurately which is the most suitable for each process - to do this, something faster is required. This thesis describes the design and implementation of an Intelligent Route Generator. The aim is to provide the planner with accurate calculations of all possible production routes m a factory. This will lead up to the selection of an optimum solution according to minimum cost and time. The ultimate goal will be the generation of fast decisions based on expert information. Background knowledge of machining processes and machine tools was initially required, followed by an identification of the role of the knowledge base and the database within the system. An expert system builder. Crystal, and a database software package, DBase III Plus, were chosen for the project. Recommendations for possible expansion of and improvements to the expert system have been suggested for future development