0000000000060008
AUTHOR
Octavian Bologa
Low-cost motion control solution for industrial manufacturing systems
This paperwork deals with a low-cost actuation solution, based upon induction motors, which was seldom used in the motion control systems, especially for the machine tools feed drives. A simulation approach, based upon a mathematical model of the induction motor, for tuning the controllers of the systems is presented. Experimental researches developed upon a two axes motion control system, both axes being driven by alternating current asynchronous motors were also performed in order to test the proposed strategies. The asynchronous motors, used as actuation devices were equipped with incremental rotary encoders and controlled by vector frequency inverters and DSP motion control cards were u…
Researches Regarding Optimizing the Accuracy of CNC Laser Cutting Machines
The experimental researches presented in this paper are aimed to improve the manufacturing accuracy of a contouring machine together with an approach to eliminate the errors which lead to a less precise part after machining.In order to eliminate the errors, the machine's feed drives were tuned leading to a more precise part. In order to validate the proposed approach, the accuracy of the machine was tested before and after the tuning process.
Researches Regarding the Usage of Titanium Alloys in Cranial Implants
In the last few decades, the concept of flexible manufacturing has started to gain more and more attention, as an adaptation of production methods to the increasingly varied demands by customers. Therefore, new procedures have been introduced as alternatives to the classical ones, a very promising one being incremental forming [. A possible application for this new procedure, targeted by the authors of this paper, is the manufacturing of custom-shaped prosthetic parts for use in various areas of human medicine. Such prostheses can have a functional role, when they target the replacing of a functional component of the human body, or an esthetic role, when they target the solving of problems …
Kinematic Solutions of a 7 DOF Robotic Arm Using Redundancy Circle and Fuzzy Models
In this paper we have presented a method to solve the inverse kinematics problem of a redundant robotic arm with seven degrees of freedom and a human like workspace based on mathematical equations, Fuzzy Logic implementation and Simulink models. For better visualization of the kinematics simulation a CAD model that mimics the real robotic arm was created into SolidWorks® and then the CAD parts were converted into SimMechanics model.
FEM Simulation of Laminated Lightweight Materials Processed through Single Point Incremental Forming
The aim of present paper is to realize the FEM simulation of laminated lightweight material processed through single point incremental forming. Thus a laminated material, aluminum - polypropylene - aluminum (Al-PP-Al), as sheet 1.2 mm thickness was used. For these material the hardening curve was determinate. These values were used to describe elastic-plastic behavior of the material during single point incremental forming process simulation. Single point incremental forming process simulation aimed to assess the distribution of values and maximum and minimum strains, the material thickness of the specimen and the technological force for the two strategies for obtaining the truncated cone s…
Adaptive neuro-fuzzy inference system for kinematics solutions of redundant robots
This written paper presents aspects concerning the implementation of the Adaptive Neuro-Fuzzy Inference System (ANFIS) in the resolution of a redundant serial robot kinematics. The kinematics solutions are divided into two categories: direct kinematics solutions and inverse kinematics solutions. To be able to control a robot the most important solutions are the ones for the inverse kinematics since one knows the position and the final orientation of the end effector and needs to determine the relative displacement or movements into the robot couplings. To obtain the optimal solutions for the inverse kinematics of a redundant robot the mathematical equations were based onto the redundancy ci…
Using the Analytic Hierarchy Process (AHP) in Evaluating the Decision of Moving to a Manufacturing Process Based Upon Continuous 5 Axes CNC Machine-tools
Abstract This paper represents the second part of the work described in the paper with the title “Decision-making tool for moving from 3-axes to 5-axes CNC machine-tool”. The problem of using either 3 axes CNC machine-tools or 5 axes CNC machine tools was presented in the first part, together with a fuzzy logic based decision support tool. This time, an AHP approach is used in order to evaluate the decision of moving to a manufacturing process based upon 5 axes machine tools. Three variants were taken into consideration and analysed. The consistency of the proposed approach was evaluated and a sensitivity analysis was also introduced.
Contributions Regarding Incremental Forming Process of Bimetallic Sheets
Incremental forming is a process with a high degree of novelty, so this paper describes first of all a series of theoretical principles of the incremental forming process. A main objective of the paper was the usage, as blanks in incremental forming process of bimetallic sheets. So the experimental researches have targeted the realising of parts with different shapes made from such type of blank. In the experimental researches was chosen as technological equipment for incremental forming the numerical controlled milling centre. The paper also present the tools used in incremental forming in order to obtain a hemispherical parts.
Low-cost solutions for manipulation tasks in manufacturing systems: balancing costs and performances
Abstract Industrial robots are distinguished from other types of machinery mainly on the basis of their programmability and adaptability to different tasks. However, the cost s of the state of the art solutions for every system within their structure became very high compared with some applications. This work presents two proposed solutions of so called robotic manipulators, which may fulfil some of the manipulating tasks specific to industrial robots while using low-cost solutions of transmission, actuation and automation systems.
Method for Estimating the Manual Nesting Process Efficiency for Profiling Machines, Based upon Image Processing Techniques
The paper presents a method for estimating the efficiency of the manual nesting process. By using the graphic file generated during the nesting process and using image processing techniques, the method allows the user to calculate the percentage of material used for manufacturing the parts. The method combines a manual approach - the user has to select some specific points on the graphic file with the mouse, with some image processing algorithms form Matlab software package.
Study of the Formability of Light Metallic Materials
There is a continuing interest in using laminated materials for the production of lightweight parts, the resulting parts having the same functionality and even an increased stiffness and length of operation compared to conventional materials. The present paper aims to study the forming behavior of the laminated materials that requires the unfolding of tests to determine the tensile mechanical properties and the intrinsic properties, determining the forming limit curves by means of the Nakajima test and the analysis of the behavior at unconventional incremental forming.
Inverse kinematics of a 7 DOF manipulator using Adaptive Neuro-Fuzzy Inference Systems
This paper was carried out objectively to explore and describe the inverse kinematics solutions of an anthropomorphic redundant robotic structure with seven degrees of freedom and human like workspace. Traditional inverse kinematics methods can have an unacceptably slow pace for the today's extremely redundant systems. The presented method uses the Adaptive Neuro-Fuzzy Inference Systems (ANFIS) editor and the Fuzzy Logic toolbox from MATLAB® which allow the investigation of various kinematical suitable solutions. ANFIS supports the determination of one degree of freedom, remaining therefore only six undetermined degrees. For better understanding of the simulations a CAD model that mimics th…
Comparative Study by Numerical Analysis on the Formability of Deep-Drawn Tailor-Welded Blanks
The realising of complex parts by welding together and then deep-drawing metal sheets made of different steel types or even different metal types can have many advantages, such as decreasing the part’s weight, reducing the manufacturing costs and an increased dimensional precision. In order to benefit from these results, a detailed knowledge of the metal sheets’ behaviour during deep-drawing is necessary. The current paper aims to compare, using numerical simulations based on the finite element method, the deep-drawing behaviour of parts made of steel sheets of different thicknesses welded together in three different manners and also of a part made of a monoblock blank.
Robot-Forming - An Incremental Forming Process Using an Industrial Robot by Means of DELMIA Software Package
The purpose of this research is to present an alternative method for manufacturing sheet metal parts using an asymmetric incremental forming process by means of an industrial robot. This method is based on designing, simulating and generating the toolpath for the tool attached to the robot using DELMIA software package. The proposed approach allows users to check for system collisions, robot joins limitations and singularity problems. After a comprehensive simulation of the movements of the robot is performed, the program code can be generated by means of a specific DELMIA function. The program can be used afterwards to control the robot during the experimental work. In order to demonstrate…
Simulated 3-axis versus 5-axis Processing Toolpaths for Single Point Incremental Forming
Abstract Accuracy and productivity of the parts manufactured by single point incremental forming (SPIF) are influenced by the proper selection of toolpaths. CAM software packages are often used for generating the toolpaths for the process. Literature survey have revealed that contour curves and spatial spirals are the most used toolpaths for SPIF. These toolpaths are generated using 3-axis approaches, meaning that the tool axis is maintained parallel to the vertical axis. The 3-axis approach was justified using 3-axis CNC milling machines as the main technological equipment for SPIF. However, nowadays, the wide spreading of both 5-axis CNC milling machines and industrial robots, with far su…
Sheet Metal Hydroforming Technology - State-of-the-Art
The present paper describes the current status of hydroforming technology in today’s global market that focuses on energy use in respect to increasing requirements especially from the automotive industry with its renaissance after the economic crisis. A vast hydroforming classification and the restrictions and drawbacks for a wider market share are also presented.
Mechatronic Contouring System for Unconventional Sheet Metal Forming Processes
This paperwork was developed in order to present the work concerning the use of mechatronic approach in the study of motion control systems for metal forming processes. The paper presents the use of low cost motion control systems, based upon induction motors, as driving systems in unconventional sheet metal forming processes. The main goal of this work was to implement a 2D contouring system for driving the active plate. The model of the system, simulations and some experimental work will be presented.
COMPARATIVE ANALYSIS OF RIGID AND FLEXIBLE STRUCTURES OF THE ECCENTRIC PRESSES
Abstract The aim of this paper is to make a comparative study of the static behaviour of the eccentric presses, using the finite elements method, on the rigid structure and on the flexible structure, respectively. The finite elements modelling of the component elements of the presses are done in two ways: node by node link type (rigid structure) or using a linking element spring damper type (flexible structure). On these two structures there is successively applied a number of static analyses, in order to determine the strain of working area and the design of the stiffness graph.
Experimental Research of the Formability of Lightweight Metallic Materials Used in Automotive Industry
This paper aims to study the plastic deformation behaviour of lightweight metallic materials in order to reduce the total weight of the vehicles without affecting their performances. For the theoretical and experimental researches presented here, among these materials the AZ31B magnesium alloy has been chosen, a representative alloy for the magnesium-zinc-aluminium alloy system. The results of the theoretical researches, made on finite elements models, were validated by means of experimental researches consisting of tensile tests, forming limit curves determination tests and AZ31B magnesium alloy drawing, respectively.
Computer assisted techniques for the incremental forming technology
The Asymmetric single point incremental forming (ASPIF) is a manufacturing technology with a high degree of novelty. Even if there are a significant number of research results reported in the literature, the industry has not been very enthusiastic to adopt and implement it on large scale. One of the main reasons for that is the lack of specific computer aided techniques and tools, which could be used to design and optimize the ASPIF process. The paper presents some methods to overcome this drawback, either by using some general purpose computer assisted tools or by developing new simple, yet effective methods. The proposed methods can be used in the preparation stage of computer automated m…
Experimental Testing of Some Polymer Materials
Abstract The research aims to test polymer materials as the plastic materials: UHMWPE and POM, to observe there characteristics, to determing how they can be used and what we can obtain from them. We wanted to see the strong and the weak values that characterize them, what kind of parts we can produce from them and in what case we can use it. By applying this tests is necessary in order to see real datas that can help you compare them, and lead you to conclusions. Using these methods of testing materials leads to the establishment of real properties of the material and to the establishment of new configurations necessary to be made to the manufactured parts.
Improving the Manufacturing Accuracy of the Profiling Machines
Abstract This paper presents the results of theoretical and experimental researches carried out with regard to the optimization of the dynamic behavior of a CNC laser cutting machine, in terms of cutting precision, for the case of flat metallic parts whose contours comprise right angles and which a profiling machine has to process continuously, without stopping in the corner points. It is aimed especially at detailing the influence of the numerical control equipment's setup on the size of the contouring errors and on the smoothness of the movement, factors that have a direct influence on the accuracy and that have been less addressed until now. The theoretical researches indicate that it is…
Inverse Kinematics for a 7 DOF Robotic Arm Using the Redundancy Circle and ANFIS Models
In this paper we have presented a method to solve the inverse kinematics problem of a redundant robotic arm with seven degrees of freedom and a human like workspace based on mathematical equations, ANFIS implementation and Simulink models. For better visualization of the kinematics simulation a CAD model that mimics the real robotic arm was created into SolidWorks® and then the CAD parts were converted into SimMechanics model.
Technological aspects regarding machining the titanium alloys by means of incremental forming
Titanium alloys are materials with reduced formability, due to their low plasticity. However, today there are high demands regarding their use in the automotive industry and in bio-medical industry, for prosthetic devices. This paper presents some technological aspects regarding the machinability of titanium alloys by means of incremental forming. The research presented in this paper aimed to demonstrate that the parts made from these materials could be machined at room temperature, in certain technological conditions.
Theoretical and Experimental Researches Regarding Multilayer Materials Used for Incremental Forming
Although this represents a relatively recent development in the industry, the composite multilayer sheets are currently encountered in almost all industrial domains, due to the density, mechanical strength and energy absorption properties that are higher than those of the blanks realised from a single material. These materials are useful especially in domains such a the automotive industry, where the vehicles must fulfil simultaneously conditions of increased passenger safety, increased comfort, increase of the loading capacity in conditions of a reduced energy consumption. First of all the paper shows the types of multilayer sheets and their areas and areas of use, then the paper analyzes …
Using an Adaptive Network-based Fuzzy Inference System to Estimate the Vertical Force in Single Point Incremental Forming
Manufacturing processes are usually complex ones, involving a significant number of parameters. Unconventional manufacturing processes, such as incremental forming is even more complex, and the establishment of some analytical relationships between parameters is difficult, largely due to the nonlinearities in the process. To overcome this drawback, artificial intelligence techniques were used to build empirical models from experimental data sets acquired from the manufacturing processes. The approach proposed in this work used an adaptive network-based fuzzy inference system to extract the value of technological force on Z-axis, which appears during incremental forming, considering a set of…
Method for improving the contouring accuracy for CNC profiling machines at the shop floor level
Computer Numerically Controlled (CNC) laser cutting machines are capable of producing high-quality precise parts. However, as cutting speeds is increased, in order to achieve higher productivity, the accuracy of the parts is affected. In order to improve the contouring accuracy of these machines, a simple straight-forward joint simulation and experimental strategy is proposed. The position controllers within the feed drives are considered the key factor in improving the dynamic behavior and consequently the contouring accuracy of a CNC laser cutting machine at the shop floor level.
Developing a Knowledge Base about the Technological Forces within the Asymmetric Incremental Forming Process
Asymmetric single point incremental forming (ASPIF) has been recognized as a solution with potential in manufacturing small batches or single sheet metal parts. The approach presented in this paper presents the development of a knowledge base regarding the values of the technological force within the ASPIF process and the influence of some technological parameters such as feed, speed of the punch, thickness of the part and step, upon them. The method is based on the use of the information provided by the CNC machine sensors. Relationships between the torques developed by the drive motors on each axes and the technological forces will be set in order to refine the raw information displayed o…
The inverse kinematics solutions of a 7 DOF robotic arm using Fuzzy Logic
This paper focuses on modeling resolving and simulations of the inverse kinematics of an anthropomorphic redundant robotic structure with seven degrees of freedom and a workspace similar to human arm. Also the kinematical model and the kinematics equations of the robotic arm are presented. A method of resolving the redundancy of seven degrees of freedom robotic arm is presented using Fuzzy Logic toolbox from MATLAB®.
Advanced Techniques used in Numerical Simulation for Deep-drawing Process
The present paper analyse the main characteristics of the numerical simulation by finite element method of the deep-drawing processes. Also the authors’ highlights the mathematical apparatus and the calculus method used for numerical simulations of metal forming processes in many of the current simulation software. The authors present the capabilities of the inverse analysis, direct analysis, implicit analysis (for springback simulation) and the optimisation analysis applied to explicit formulations.
Researches Regarding the Use of Fuzzy Controllers within CNC Feed Drives
This paper presents some simulation based upon a dynamic model of a feed-drive within the structure of a CNC machine tool. A DC servomotor was considered as actuation device for the feed drive. For a given set of parameters for the position controller, two fuzzy types of fuzzy controllers were tested by means of simulation. The first fuzzy controller was a proportional one, with one input and one output, while the second one was a two variables one, with two inputs and one outputp.
IMPROVING CNC MACHINE TOOLS ACCURACY USING MODELING AND COMPUTER SIMULATION TECHNIQUES
Abstract The position was one of the first parameters that required the introduction of automatic control process. One of the most representative applications is represented by the feed drives of the computer numerically controlled (CNC) machine tools. Today, it is possible to use computer simulation techniques in analysing and synthesising position control systems. Thus, the behaviour of the CNC machine tools feed drives can be treated much more realistically. It is the purpose of this paper to show how simulation can be used to accurately represent, predict and improve the performance of a CNC machine tool feed servo drives.
Motion control systems for machine tools - a mechatronic approach by means of simulation
Tuning the control parameters of the feed drives for existing state of the art CNC machine tools, or retrofitting obsolete machine tools requires a close understanding of the position control process. The use of a mathematical model of the feed drive, combined with a computer simulation process is needed in order to fulfill the above mentioned tasks. In this paper some simulation tools for studying the CNC motion control systems are presented. Both single axis positioning regime and biaxial linear and circular interpolation regime were taken into consideration. The main goal of the research was to offer a handson integrated simulation tools compatible and able to use for improving the perfo…
Zigler-Nicols PID Tuning Method for Position Control of a Mobile Robot
This paper presents the implementation and the tuning of PID controller for a mobile platform with differential steering. It presents a mobile platform built in the Department of Industrial Machinery & Equipment, of the Engineering Faculty of Sibiu for an European contest. In a first phase, a brief introduction to PID controller is made, followed by a description of the various robot's components and traction principles underlying locomotion of mobile platforms. At the end the paper contains several principles of tuning the PID controller for the mobile robot.
Another Approach for Redundancy Resolution of a 7 DOF Robotic Arm
In this paper we have presented a method to solve the inverse kinematics problem of a redundant robotic arm with seven degrees of freedom and a human like workspace based on mathematical equations, Fuzzy Logic implementation and Simulink models. For better visualization of the kinematics simulation a CAD model that mimics the real robotic arm was created into SolidWorks® and then the CAD parts were converted into SimMechanics model.
Experimental Researches Regarding Strain Measurement of Incrementally Formed Sheet Metal Parts Done Using an Industrial Robot
This paper aims to provide results regarding the measurement of the strains in the material of sheet metal parts which have been incrementally formed. The incremental forming of the steel sheets has been performed with the aid of a KUKA KR 6 industrial robot on a specially constructed stand, and the measurement of the strains has been done using ARAMIS optical measurement system. The trajectory of the forming punch which is attached to the robot was designed using CATIA V5 and the movements of the robot were designed and simulated in DELMIA software. DELMIA generated the program code needed for the robot to execute the desired movements in order to form the sheet metal parts.
Computer Simulation for the Study of CNC Feed Drives Dynamic Behavior and Accuracy
In the application of CNC feed drives it is desirable to predict the servo performance. By using computer simulation techniques it is possible to construct an accurate model of the servo drive. This simulation procedure makes it possible to anticipate machine design problems and correct them. This paper deals with a model of a feed drive, which consists of a motion control system driven by a DC motor. Both position and velocity feedback loops are present in the structure of the system. By means of MATLAB & Simulink software, simulation diagrams were built in order to test the behaviour of the system. Experimental data are also presented in order to confirm the accuracy of the theoretical mo…
ROUGHNESS CONTROL OF PARTS OBTAINED THROUGH INCREMENTAL SHEET FORMING
Abstract The present paper adresses the issue of controlling the quality of surface in the case of a new sheet metal forming process by which various curved shells are formed without the help of expensive dies. The roughness of the surface which comes in direct contact with the punch at incremental sheet forming suffers an obvious worsening compared to the initial blank surface roughness. The present paper discusses the measuring of the roughness of parts obtained through the previously mentioned process and highlights the factors that influence it. There were taken into account the initial roughness of the punch, the punch diameter and the friction coefficient between the punch and the bla…
Method for Manufacturing Custom-Shaped Prosthetic Parts from Titanium Alloys by Incremental Forming Using Industrial Robots
The last decade has shown an increasing interest in a new class of forming processes known as Incremental Sheet forming (ISF). A possible application for this new procedure, targeted by the authors of this paper, is the manufacturing of custom-shaped prosthetic parts for use in various areas of human medicine. Such prostheses can have a functional role, when they target the replacing of a functional component of the human body, or an esthetic role, when they target the solving of problems related to the appearance of the human body. In this paper the authors aim to determine the strain hardening curves for the titanium alloy Ti6Al4V at room temperature and at 800°C. The incremental forming …
Determination of Technological Forces in the Incremental Forming Process
The paper presents a joint theoretical and experimental approach to determine the technological forces within the asymmetric single point incremental forming ASPIF process, based upon a theoretical model, image processing and data acquisition. The first step of this approach was to develop a theoretical model of the forces within the process, based upon the model of a mechanical feed drive of a CNC milling machine. By means of this model, relationships between the resistant torque at the motor spindle level and the technological force on the movement axis could be determined. Using an image processing method, which allowed the user to extract information within the machines operator panel a…
Simulation approach for improving CNC milling machines accuracy for single axis motion
CNC milling machines are widely used in manufacturing processes. In time, their accuracy is decreasing, which directly influences the accuracy of the manufactured parts. This research proposes a simulation-based method for improving the accuracy of the above mentioned machines, which is suitable to be applied at the shop floor level. A model of the feed drive, using a dc servomotor as actuator, is the core of the proposed approach. Matlab & Simulink based simulation diagrams were built in order to test the behavior of the system.
From part to point cloud, the modelling of a 3D part
The present paper focuses on the development of the composite materials in the automotiv industry by making a comparative analysis between a 3D model of the part and a real part made by a composite material, measuring the part using the point cloud. The aim is to obtain a high modeling and a more clear visualization of the composite material part.
Model of a CNC Feed Drive for On-Site Tuning of the Controllers for Single Axis Motion
The accuracy of CNC machine-tools is heavily influenced by the correct tuning of the feed drives controllers. While an initial tuning is performed by the machine-tool manufactures, in time the values have to be changed by the user in order to preserve positioning and contouring accuracy of the machine. This paper presents a model of a CNC feed drive, for a particular CNC machine-tool, but with a high degree of generality. The objective is to provide the user the necessary knowledge, together with a simple, yet accurate simulation tool, in order to assist him in the process of tuning the controllers.
Decision-making Tool for Moving from 3-axes to 5-axes CNC Machine-tool
Abstract Nowadays most of the parts within machine-building industry are machines on CNC machine-tools. According to their mechanical and kinematic structure, CNC machine-tools can be divided into 3-axes and 5-axes ones. Each type has its advantages and drawbacks and choosing between them could be a very difficult process. This paper presents a decision support tool for aiding the process of selecting between using and/or buying either a 3-axes CNC milling machine or a 5-axes milling machine, based upon fuzzy logic. The tool was built using the Fuzzy Logic Toolbox and the fuzzy graphical user interface (GUI) within Matlab software package.
Motion control of medium size CNC machine-tools-A hands-on approach
This paperwork presents an integrated approach based upon simulation and experimental work for reducing the positioning errors of a small to medium size CNC machine-tools. The approach is intended to be used at the shop-floor level and therefore it is based upon a straight-forward model of the feed drive. The model was particularized with specific data from a CNC milling machine and simulation techniques were used to predict the behavior of the system. Only the control parameters of the feed drive which may be altered by the user, without modifying the structure of the CNC controller were taken into consideration and tuned. Simulation results and experimental data gathered before and after …
Modular device for determining forming limit curves – a cost effective aproach
Abstract The paper presents the realising and functioning of a modular device for testing the formability of metal sheets. By using the device it is possible to realise experimentally the tests needed for drawing the forming limit curves using the Nakajima and Marciniak methods, but there can be also done researchs on deep-drawing. The results gathered from the tests were validated by numerical simulations using the finite element method. The device was designed at the Research Center for Metal Forming of the “Lucian Blaga” University of Sibiu and realised with the support of S.C. Uzina Mecanica Marsa – Sibiu
Considerations on Cutting Regime Influence of NC Laser Cutting Machine Tool on Processed Surface Quality
This paper presents the study of the influence of cutting parameters on surface quality in laser cutting of metallic materials. In this paper, it is shown which of the cutting parameters have the greatest influence on the quality of the processed surfaces by measuring various roughness parameters. After the experimental research was carried out a ranking of the factors of influence on the response functions was made, also graphs of dependency to various parameters of roughness were made.
Building 3D Geometric and Kinematic Models of Five-Axis Machine-Tools for Manufacturing Prosthetic Devices
The paper presents the process of building and testing a geometric and kinematic model of a five-axis machining center, which can be used for accurate cutting processes simulation of complex parts. After building the model, it was be tested by simulating the machining process of a hip joint prosthetic device. The prosthetic device was chosen because of its complex shape and because it was obtained by a 3D scanning process, which means that the part was reconstructed using meshes, instead of surfaces, which makes the toolpath control more difficult.