Tool Displacement Research Articles

Study of the forming limit of 6063 aluminum alloy perforated sheet under in-plane and out-of-plane stretching conditions

The current investigation deals with the forming process of Perforated Sheet Metal (PSM) process. The goal of the work is to determine by experimental and numerical methods the Forming Limit Diagrams (FLDs) of an Al-Mg-Si aluminum alloy. In order to achieve this objective, Specimens of different widths, obtained by cutting portions from two opposite sides of a circular blank, were used. The FLDs were determined for the two forming tests: MARCINIAK and NAKAZIMA tests. This choice is motivated by the simplicity of the shapes of the blanks and punches used during these tests, but also in order to measure these curves in both flat (MARCINIAK) and curved (NAKAZIMA) zones. A measurement technique using Stereo-Digital Image Correlation (Stereo-DIC) was implemented. For the sake of comparison, the same tests were performed on Non-Perforated Sheet Metal (NPSM). The experimental FLDs were successfully assessed using simulations in Abaqus finite element code. It is namely found that the safe forming region obtained by NAKAZIMA test is higher than that obtained with MARCINIAK test. Furthermore, the maximum tool displacement in NAKAZIMA tests is double that of MARCINIAK tests for all perforated specimens.

Информационные свойства частотных характеристик динамической системы резания при диагностике износа инструментов

Introduction. One of the directions for increasing the efficiency of cutting is related to the creation of tool wear diagnostic systems. Algorithms and devices have been developed that evaluate wear based on analysis of the vibroacoustic emission signal. These algorithms, as a rule, do not reveal the nature of its formation and the reasons for the change as wear develops. Subject. The paper is devoted to the analysis of the reasons for changes in vibration properties with the development of tool wear. The aim of the work is to study the changes in the frequency characteristics of a dynamic cutting system caused by the development of wear, and to build diagnostic information models on this basis, as well as its use in industry. Method and methodology. The results of mathematical simulation of a perturbed dynamic cutting system are presented, in which the observed vibration sequences are a consequence of disturbances transformed by a dynamic system, the parameters of which depend on wear. Two frequency ranges are considered. Results and discussions. The first range includes frequencies that lie within the bandwidth of the instrument subsystem. The second is outside of it. In the first frequency range, it has been analytically and experimentally proven that the development of wear leads to fundamental changes in the frequency properties of the cutting system as a converter of disturbances into tool vibrations. There is a shift in the natural frequencies of the oscillatory circuits formed by the cutting system, a decrease in its quality factor, and as wear develops, some identified features of the vibration spectra appear, including the ratio of the low-frequency and high-frequency parts of the spectrum, etc. In the second frequency range, a model of force emission in the form of a random pulse sequence is considered and wear is displayed in it. The results of studying the coherence function between the forces acting on the tool and vibrational displacement are presented. Information models of wear are proposed, an example of an information model of wear and the results of its use in industry are given.

ВЛИЯНИЕ СМЕЩЕНИЯ ИНСТРУМЕНТА ПРИ СВАРКЕ ТРЕНИЕМ С ПЕРЕМЕШИВАНИЕМ НА МЕХАНИЧЕСКИЕ СВОЙСТВА И ОБРАЗОВАНИЕ ЗОН СВАРНЫХ СОЕДИНЕНИЙ АЛЮМИНИЕВОГО И МЕДНОГО СПЛАВОВ

The article examines the effect of welding tool displacement on copper and aluminum during friction stir welding on the formation of microstructure and mechanical properties of a dissimilar weld. The corresponding welding modes were considered in the work: welding tool rotation speed 900 rpm, welding speed 25 mm/min, mixing varied from 0 to 3 mm for copper or aluminum. The most optimal displacement during friction stir welding was the location of the pin of 0.5 and 1 mm on copper, which allows the formation of a composite structure of the core and the thermal deformation zone. At these positions of the tool pin relative to the line of contact of the metals, the mechanical properties of the weld are closer to those of the most ductile material (aluminum). The welding mode parameter (displacement) affects the formation and volumetric content of intermetallic layers. If the thickness of the intermetallic layers does not exceed 4-5 µm, then increased values of the mechanical strength of the welded dissimilar joint are observed.

METHODOLOGY FOR STUDYING ACCURACY PARAMETERS
 IN THE PROCESS OF RESTORING THE VALVE SEATS

In this article a methodology for researching the parameters of forming in the process of processing valve seats
 of an internal combustion engine valve timing gear in an automobile repair industry was described.
 The practical implementation of this methodology was carried out using laser triangulation sensors based on the
 developed device for boring valve seats. Experimental dependences of the cutting tool displacement on various processing modes were obtained. Practical recommendations were made on the selection of cutting mode ranges to ensure
 the required precision parameters when restoring valve seats.

Accuracy of instrument tip position using fiber optic shape sensing for navigated bronchoscopy

The purpose of this study was to evaluate the accuracy of a method for estimating the tip position of a fiber optic shape-sensing (FOSS) integrated instrument being inserted through a bronchoscope. A modified guidewire with a multicore optical fiber was inserted into the working channel of a custom-made catheter with three electromagnetic (EM) sensors. The displacement between the instruments was manually set, and a point-based method was applied to match the position of the EM sensors to corresponding points on the shape. The accuracy was evaluated in a realistic bronchial model. An additional EM sensor was used to sample the tip of the guidewire, and the absolute deviation between this position and the estimated tip position was calculated. For small displacements between the tip of the FOSS integrated tool and the catheter, the median deviation in estimated tip position was ≤5 mm. For larger displacements, deviations exceeding 10 mm were observed. The deviations increased when the shape sensor had sharp curvatures relative to more straight shapes. The method works well for clinically relevant displacements of a biopsy tool from the bronchoscope tip, and when the path to the lesion has limited curvatures. However, improvements must be made to our configuration before pursuing further clinical testing.

An experimental approach to characterize the performance of PCD and PCBN tools in milling nano Al-8081-Zr/Mg/TiO2 metal matrix composites using multi-sensor data fusion

To prevent the quality of the finished product from declining, precision manufacturing procedures need reliable cutting tool wear detection. Cutting tool material, workpiece attributes, cutting conditions and conditions, and excessive cutting forces creating vibrations causing chatter impacting tool wear finally leading to tool failure all have an impact on tool performance. This paper presents a multisensory data fusion approach that assigns sensors at nearfield sites during the machining process to monitor the tool condition. The study investigates the performance of polycrystalline diamond (PCD) and Polycrystalline Cubic Boron Nitride (PCBN) cutting tools during the machining of nano metal matrix composites reinforced with Zr/Mg/TiO2 (15%). The method correlates signal features with experimental results to provide a reliable empirical approach to monitor the cause of tool flank wear and displacement, leading to failure. The experimental investigation it is found the cutting forces showed significant effect on flank wear affecting surface finish and tool life. Tool performance was successful monitoring and predicted instantly based on the signature analysis of vibrations and forces during machining helped accurately analyzed factors affecting tool wear at uncertain cutting conditions using FDA analysis. The study provides insights into the PCD and PCBN tools’ performance characteristics.

A systematic approach for data acquisition for tool modelling and analysis of wear-dependent tool deflections during milling Inconel 718

Nickel-based superalloys are commonly used for components in the aerospace industry. Due to their favorable mechanical properties, such as high strength and corrosion resistance, these materials are suitable for use under extreme temperature conditions. However, the poor machinability results in high process forces and high tool wear, and, therefore, large tool displacements, so that high manufacturing tolerances are often difficult to achieve. Simulation systems can be used to optimize the process. The data acquisition for the development of the models required is challenging. In the following, a method for in-situ digitization of the tool is presented. Furthermore, the occurring tool deflections during the machining of Inconel718 are analyzed for different wear conditions to serve as basis for the parameterization of simulation models.

Design and Analysis of Ultra-Precision Smart Cutting Tool for In-Process Force Measurement and Tool Nanopositioning in Ultra-High-Precision Single-Point Diamond Turning.

Ultra-high-precision single-point diamond turning (SPDT) is the state-of-the-art machining technology for the advanced manufacturing of critical components with an optical surface finish and surface roughness down to one nanometer. One of the critical factors that directly affects the quality of the diamond-cutting process is the cutting force. Increasing the cutting force can induce tool wear, increase the cutting temperature, and amplify the positioning errors of the diamond tool caused by the applied cutting force. It is important to measure the cutting force during the SPDT process to monitor the tool wear and surface defects in real time. By measuring the cutting force in different cutting conditions, the optimum cutting parameters can be determined and the best surface accuracies with minimum surface roughness can be achieved. In this study a smart cutting tool for in-process force measurement and nanopositioning of the cutting tool for compensating the displacements of the diamond tool during the cutting process is designed and analyzed. The proposed smart cutting tool can measure applied forces to the diamond tool and correct the nanometric positioning displacements of the diamond tool in three dimensions. The proposed cutting tool is wireless and can be used in hybrid and intelligent SPDT platforms to achieve the best results in terms of optical surface finish. The simulation results are shown to be almost consistent with the results of the derived analytical model. The preliminary results pave the way for promising applications of the proposed smart cutting tool in SPDT applications in the future.

Process strategies for milling of dimples on tapered roller bearings

Frictional losses occur in tapered roller bearings, particularly at low rolling speeds, which pose a risk of wear. The increased friction losses are a result of insufficient lubricant film thicknesses in the rolling and rib contact. Micro-lubrication dimples can be used to induce additional lubricant into the contact zone and minimize friction. The aim of this paper is therefore to implement a suitable machining strategy for the production of defined microstructures for tribologically optimized applications and to identify relationships between geometry formation and process parameters. For this purpose, the microstructure milling process was first modelled with a material removal simulation, including tool displacement. Additionally the kinematic limits of the machine tool were determined. The tool displacement was determined experimentally for this purpose. Subsequently, the findings from the simulation were used to induce microstructures in a defined manner on tapered roller bearings made of hardened 100 Cr6 steel. The investigations showed that the defined generation of lubrication dimples is possible with the developed machining strategy. Due to the inclination of the inboard bearing, there is a deviating depth of engagement when the tool penetrates, which also increases the tool displacement. As a result of the microstructure milling process, burr formation occurs, which shows a dependence on cutting speed and structure alignment. Increased burr formation and tool wear at structure orientations of 45° and 70° were found.

Smoothing tool design and performance during subaperture glass polishing.

During subaperture tool grinding and polishing, overlaps of the tool influence function can result in undesirable mid-spatial frequency (MSF) errors in the form of surface ripples, which are often corrected using a smoothing polishing step. In this study, flat multi-layer smoothing polishing tools are designed and tested to simultaneously (1)reduce or remove MSF errors, (2)minimize surface figure degradation, and (3)maximize the material removal rate. A time-dependent convergence model in which spatial material removal varies with a workpiece-tool height mismatch, combined with a finite element mechanical analysis to determine the interface contact pressure distribution, was developed to evaluate various smoothing tool designs as a function of tool material properties, thicknesses, pad textures, and displacements. An improvement in smoothing tool performance is achieved when the gap pressure constant, h¯ (which describes the inverse rate at which the pressure drops with a workpiece-tool height mismatch), is minimized for smaller spatial scale length surface features (namely, MSF errors) and maximized for large spatial scale length features (i.e.,surface figure). Five specific smoothing tool designs were experimentally evaluated. A two-layer smoothing tool using a thin, grooved IC1000 polyurethane pad (with a high elastic modulus, E p a d =360M P a), thicker blue foam (with an intermediate modulus, E f o a m =5.3M P a) underlayer, and an optimized displacement (d t=1m m) provided the best overall performance (namely, high MSF error convergence, minimal surface figure degradation, and high material removal rate).

Stockpile Volume Estimation Calculation Based on Terrestrial Laser Scanner (TLS) Data Acquisition and 3D Surface Visualization

Stock taking is a series of activities to calculate the stock of goods that are still stored in the warehouse to be marketed. There are many activities covered in it, ranging from calculating the number of goods, conducting direct inspections, and structuring that will facilitate business operations when a certain product is needed. One of these activities is also carried out in the mining sector. Coal stock-taking is a survey activity carried out in the coal yard area to calculate the volume of the stockpile and coal tonnage after being multiplied by the density value. Large-dimensional coal stocking must be carried out quickly, accurately and in detail. The need for this can be obtained using laser scanner technology. Laser scanner is a tool designed to scan the surface of an object and represent it in 3D in the form of a height density point cloud. Based on this, in carrying out stock-taking calculation activities, measurements are needed which mainly aim to find out the stockpile volume and density in the fourth quarter of the Adipala PLTU Coal Yard. Stockpile measurement method using volumetric method. Measurement using a Laser Scanner tool to obtain the shape of the stockpile area is by seizing the entire surface of the Stockpile by setting the resolution of the density of coordinate points (x, y, z) as needed. Tool displacement when measurements are made on every detail of the Stockpile curve. Based on the calculation results, it is known that the volume value of the coal stockpile on the west side coal yard is 121,420,574 m3 and the east side coal yard is 88,230,355 m3 on. The total volume of coal amounted to 209,650,929 m3 then multiplied by the density of the bulk density survey results and obtained the tonnage of 180,384,417 MT.

Effect of Milling Processing Parameters on the Surface Roughness and Tool Cutting Forces of T2 Pure Copper.

In this paper, the responses of machined surface roughness and milling tool cutting forces under the different milling processing parameters (cutting speed v, feed rate f, and axial cutting depth ap) are experimentally investigated to meet the increasing requirements for the mechanical machining of T2 pure copper. The effects of different milling processing parameters on cutting force and tool displacement acceleration are studied based on orthogonal and single-factor milling experiments. The three-dimensional morphologies of the workpieces are observed, and a white-light topography instrument measures the surface roughness. The results show that the degree of influence on Sa (surface arithmetic mean deviation) and Sq (surface root mean square deviation) from high to low level is the v, the f, and the ap. When v = 600 m/min, ap = 0.5 mm, f = 0.1 mm/r, Sa and Sq are 1.80 μm and 2.25 μm, respectively. The cutting forces in the three directions negatively correlate with increased cutting speed; when v = 600 m/min, Fx reaches its lowest value. In contrast, an increase in the feed rate and the axial cutting depth significantly increases Fx. The tool displacement acceleration amplitudes demonstrate a positive relationship. Variation of the tool displacement acceleration states leads to the different microstructure of the machined surfaces. Therefore, selecting the appropriate milling processing parameters has a positive effect on reducing the tool displacement acceleration, improving the machined surface quality of T2 pure copper, and extending the tool's life. The optimal milling processing parameters in this paper are the v = 600 m/min, ap = 0.5 mm, and f = 0.1 mm/r.

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 the temperature rise of the Spindle from affecting the accuracy during the machining process, typically, the factory will warm up the machine before the manufacturing process. However, if there is no way to understand the tool spindle's thermal deformation, the machining quality will be greatly affected. In order to solve the above problem, this study aims to predict the thermal displacement of the machine tool by using intelligent algorithms. In the practical application, only a few temperature sensors are used to input the information into the prediction model for real-time thermal 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 to integrate Long Short-Term Memory (LSTM) with Support Vector Machine (SVM). The experimental results show that the prediction performance of LSTM-SVM is higher than that of other machine learning algorithms.

Inverse Analysis of Chatter Vibration Information of Circular End Milling Based on Two Dimensional Discrete Fourier Transform of Machined Surface Pattern Reconstructed from Multiple Images

It is known that chatter marks are formed on the machined surface when chatter vibration occurs during cutting. This paper proposes a method for inverse analysis of the frequency and phase difference of chatter vibration during cutting based on the periodicity of the chatter mark on circular machined surface analyzed by the two-dimensional discrete Fourier transform. The chatter mark on the circular machined surface was reconstructed on the image by projecting multiple images taken by a digital camera of the machined surface onto the circular machined surface on the computer, based on the camera calibration using the accurate table feed of the machine tool. The chatter vibration information, which was obtained by the proposed method based on the two-dimensional discrete Fourier transform of this reconstructed chatter mark image, was compared with the information analyzed from the tool displacement during cutting. As a result, the proposed process is found to be effective as an inverse analysis method to estimate the chatter vibration when end milling the curved surface.

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.

Analysis of automated surface roughness parameter support systems based on dynamic monitoring

Introduction. Domestic and foreign works on the milling of complex-profile surfaces with a ball-end tool were analyzed. Methods of surface quality control and ways to provide amplitude parameters of roughness, based on research data and field experiments, were considered. Theoretical provisions on the determination of cutting forces and the results of vibroacoustic diagnostics were presented.Materials and Methods. The methods of correlation analysis, comparison and generalization of the results were applied. The data were calculated at different tool angles, taking into account the instantaneous cutting forces, and were fixed in the range of values of the variable feed per tooth (fz) and the angle of inclination of the surface (γ). The vibroacoustic diagnostic data and theoretical data of the presented model at different tool inclination angles were verified by experiment. Consequently, such methods can be used to predict surface roughness parameters.Results. The relationship between cutting forces, tool inclination angle, and vibroacoustic diagnostics data was found. A model of the cutting force and tool displacements was formulated taking into account the inclination of the surface. The optimal range of the inclination angle of the tool to the surface to be machined, at which the minimum values of the amplitude parameters of roughness were achieved, was determined. The sound vibrations obtained empirically, presented in spectral and wave forms, were in good agreement with data from other sources. This allowed us to conclude about the feasibility of forecasting and monitoring roughness parameters in real time through acoustics.Discussion and Conclusions. It was established that the growth of forces in the direction ae(X) and fz(Y) was observed at γ > 40°. This was due to the distribution of the components of the cutting force along the cutting edge and depended on the inclination of the surface. The amplitude parameters decreased when the angle increased from 10 to 40 degrees. The found interrelations of force analysis, processing directions, and vibroacoustic diagnostics have validated the use of vibroacoustic diagnostics to predict surface roughness. Acoustic diagnostics, regardless of the layout of technological equipment, enables to quickly adjust the sound device and assess the impact of cutting modes on roughness parameters.

Implementation of DDS Cloud Platform for Real-Time Data Acquisition of Sensors for a Legacy Machine

Industry 4.0 (I4.0) is a multidisciplinary engineering principle combing the IoT (Internet of things), big data, and cloud computing to cope with the dynamic changing industry. In this paper, the DDS (data distribution service) communication protocol was employed to implement a cloud platform for data acquisition from various sensors on a precision legacy machine tool including an accelerometer and sound, temperature, brightness, and humidity sensors. The sensor signals were acquired using Raspberry Pi as the edge device, then published to the cloud using the DDS application, and stored in the MySQL database. Using the Django web server, the acquired sensor signals could be shown in real time on the webpage via a combination of MQTT and Node-RED. In addition, the motion displacement of the machine tool detected by the encoder could be recorded through the edge device for further performance examination. With the proposed DDS cloud platform, it is demonstrated that a legacy machine can enable sensing and communication abilities such that the development of a smart machine is achievable for future I4.0 application.

Necking limit analysis of thin wall aerosol can

Abstract Because of thin wall thicknesses and closed bottom ends of the extruded aerosol can, the necking limit analysis needs intensive investigation. The numerical analysis of the necking process of 0.45 mm thickness pure aluminum aerosol can was carried out. The result indicated that the length of the aerosol can wall, which is not fixed by the bottom die and the angle of inclination of necking tools are important factors that affect the development of deformation boundary limits due to plastic instability of local buckling. The fraction of taper angle of tool becomes more series parameter while necking at larger free length and it needs more concentration. Instead, the ratio of necking tool displacement to the total free length to initiate buckling was increased while increasing free length.

Piezoelectric active damper for surface roughness improvement in hard turning processes

Surface roughness and profile accuracy on rolling or sliding surfaces are critical for the wear and fatigue of a component. A high roughness or poor profile accuracy results in higher friction and higher wear rate of the surface. One of the major factors affecting the surface roughness is chatter vibrations. This paper presents a novel design and development of an active damper for chatter suppression of hard turning processes using a piezoelectric actuator and strain signal for chatter detection. The active damper consists of a piezoelectric actuator with an embedded strain gauge for measuring the vibration displacement. In this work, the radial strain signal as a result of radial chatter vibrations from the strain gauge is used as a feedback signal to the actuator using a feedback controller. A fixture was designed using special stiffeners such that it limited the tool displacements in the tangential and feed directions to only 0.2 µm and 0.4 µm, respectively, while allowing for movement in the radial direction in the actuator’s force direction. The experimental results showed a significant suppression in chatter vibrations and improvement of surface roughness using the proposed active damper. A reduction of 83% in surface roughness (Ra) was observed during the cutting process. The details of the tool design, control design, hardware implementation and system validation are given hereinafter.

Task Space Model Predictive Control for Vineyard Spraying with a Mobile Manipulator

In this paper, a Model Predictive Control (MPC)-based approach for vineyard spraying is presented, able to adapt to different vine row structures and suitable for real-time applications. In the presented approach, the mobile base moves along a row of vines while the robotic arm controls the position and orientation of the spray nozzle. A reference lawnmower pattern trajectory is generated from the vine canopy description, with the aim of minimizing waste while ensuring vine coverage. MPC is used to compute the trajectory of the vehicle along the row and the manipulator tool trajectory, which follow the spray reference, while minimizing vehicle acceleration and tool displacement. The manipulator tool velocity commands provided by the MPC algorithm are tracked using task space control. The presented approach is evaluated in two experiments: a vineyard spraying scenario and an external evaluation scenario in an indoor environment equipped with the Optitrack camera system.