scholarly journals Actuator and Process Development for Vibration Assisted Turning of Steel

2021 ◽  
Author(s):  
Martin Schwarze ◽  
Carlo Rüger ◽  
Oliver Georgi ◽  
Hendrik Rentzsch ◽  
Holger Pätzold
Keyword(s):  
Process Development ◽  
Chip Thickness ◽  
Negative Influence ◽  
Ductile Materials ◽  
Industrial Project ◽  
System A ◽  
Feed Direction ◽  
Cyclic Movement ◽  
Tool Shank ◽  
Chip Breakage

Due to continuous tool engagement, turning processes tend to form long chips when machining ductile materials. These chip shapes have a negative influence on process performance and productivity. One approach to improve chip breakage is superimposition of vibrations in feed direction of the turning process, which leads to a modulation of uncut chip thickness. In a joint industrial project with Schaeffler Technologies AG & Co. KG, Fraunhofer IWU developed an oscillating actuator for turning. The actuator converts a rotational movement of a drive motor into a translational vibration via an eccentric gear. The tool shank is mounted in solid joint assemblies. With this prototypical system, a cyclic movement of the tool in feed direction can be realized. The typical operating parameters of the actuator is within the range of 1...100 Hz with adjustable vibration amplitudes up to 0.6 mm peak-to-peak. A significant improvement in chip breaking during the machining of steel 1.0503 was shown in cutting tests.

scholarly journals Disturbance of the Regenerative Effect by Use of Milling Tools Modified with Asymmetric Dynamic Properties

2020 ◽  
Vol 4 (3) ◽  
pp. 67
Author(s):  
Jonas Baumann ◽  
Andreas Wirtz ◽  
Tobias Siebrecht ◽  
Dirk Biermann
Keyword(s):  
Dynamic Properties ◽  
Constant Width ◽  
Chip Thickness ◽  
Stability Limit ◽  
Dynamic Compliance ◽  
Depth Of Cut ◽  
Regenerative Effect ◽  
The Stability ◽  
Tool Shank ◽  
Milling Tools

Milling processes are often limited by self-excited vibrations of the tool or workpiece, generated by the regenerative effect, especially when using long cantilevered tools or machining thin-walled workpieces. The regenerative effect arises from a periodic modulation of the uncut chip thickness within the frequencies of the eigenmodes, which results in a critical excitation in the consecutive cuts or tooth engagements. This paper presents a new approach for disturbing the regenerative effect by using milling tools which are modified with asymmetric dynamic properties. A four-fluted milling tool was modified with parallel slots in the tool shank in order to establish asymmetric dynamic characteristics or different eigenfrequencies for consecutive tooth engagements, respectively. Measurements of the frequency response functions at the tool tip showed a decrease in the eigenfrequencies as well as an increase in the dynamic compliance in the direction of the grooves. Milling experiments with a constant width of cut and constantly increasing axial depth of cut indicated a significant increase in the stability limit for the specific preparations of up to 69%.

scholarly journals IMPLEMENTATION OF PROCESS MANAGEMENT IN THE FIELD OF TRADE AS IMPORTANT SOCIO-ECONOMIC SYSTEM

2021 ◽  
Author(s):  
Oleksandr Olshanskiy ◽  
Svitlana Tkachova ◽  
Olha Tkachenko
Keyword(s):  
Economic System ◽  
Business Process ◽  
Process Management ◽  
Business Processes ◽  
Process Development ◽  
Reference Model ◽  
Negative Influence ◽  
Process Approach ◽  
Added Value ◽  
Management Decision

The article focuses on the analysis of the company process management in the framework of modern organizational and economic concepts. This approach contributes to creating an extraordinary possibility of leveling out the negative influence of the environment factors and achieving a stable position for the company in the services market. The paper offers the system vision of the company's process management problems as a set of interconnected and interacting elements of the system. In present time economic reality, this county's companies' performance is entirely dependent on the ability to transform the key company processes into strategic initiatives aimed at maximizing customer satisfaction and the company's ability to react and forecast market changes. At the same time, the environment unpredictability and rapid dynamics constantly change the conditions under which companies operate. In view of this, the urgent task of operational response to various kinds of change arises, since the timely reaction of the company management of to changes in the environment can provide a long-term sustainable development of the company. Bringing the level of companies’ business process management up to meet the requirements of the internal and external environment will contribute to improving the overall level of efficiency of its business activities. As a result of the research, the process management of the enterprise has been analyzed in the framework of modern organizational and economic concepts, namely, the process approach has been considered and implemented in the field of trade as important socio-economic system. It is proved that the implementation of the process approach in the theory of management decision-making contributed to the creation of the architecture of the business process system of enterprises. The main achievements of the theory of process management are implemented in the developed reference model of the business process "Development of a strategy for the development of trade enterprises", which ultimately allows to improve the system of development and strategic management decisions. The proposed reference model can be taken as a basis for modeling the main business processes that create added value of the enterprise. The interdisciplinary nature of the process management theory is constantly gaining volume and becoming one of its distinct competencies.

scholarly journals Electrospinning – 100 Years of Investigations and Still Open Questions of Web Structure Estimination

2018 ◽  
Vol 18 (4) ◽  
pp. 398-404 ◽  
Author(s):  
Virginija Kleivaitė ◽  
Rimvydas Milašius
Keyword(s):  
Process Development ◽  
Fibre Diameter ◽  
Negative Influence ◽  
Electrospinning Process ◽  
Product Introduction ◽  
Web Structure ◽  
Open Questions ◽  
History Of ◽  
Quality Of Structure

Abstract The article presents an overview of electrospinning process development from the first investigations in the field of behaviour of liquids in an electrostatic field to the electrospinning methods and investigations in the 21st century. The article presents the history of electrospinning process development, the main problems that are solved, and also indicates the gaps in the field of standardisation of nanofibrous web structure measurement and estimation. There are a lot of works in which authors analyse influences of various parameters on the electrospinning process or on the structure of electrospun web, whereas the majority of them do not analyse the quality of structure using mathematical criteria. Such a situation leads to different conclusions and makes it impossible to compare various works by different authors. Despite numerous studies in electrospinning, investigations in the electrospun nanofibrous web estimation are not sufficient. Until now, a unique standard method for measuring and estimating the fibre diameter and web porosity has not been developed. The necessity of such a method and standards is obvious, and the lack of such a standard could have a negative influence on the electrospun product introduction into the market.

Two Dimensional Vibration-Assisted Micro-Milling: Kinematics Simulation, Chip Thickness Computation and Analysis

2010 ◽  
Vol 97-101 ◽  
pp. 2779-2784 ◽  
Author(s):  
Hui Ding ◽  
Shi Jin Chen ◽  
Kai Cheng
Keyword(s):  
Amplitude Ratio ◽  
Chip Thickness ◽  
Normal Direction ◽  
Spindle Speed ◽  
Micro Milling ◽  
Two Dimensional ◽  
Simulation Studies ◽  
Feed Direction ◽  
Kinematics Simulation ◽  
Full Factorial

Two dimensional vibration-assisted machining is applied into micro-milling to improve cutting accuracy and prolong tool life. In this paper, the tool tip path of two dimensional vibration-assisted micro-milling (2-D VAMM) with different vibrating parameters is simulated and analyzed. And the computation module of chip thickness in 2-D VAMM is proposed, based on which the chip thickness characteristics is investigated using two evaluating indicators: free time ratio (FTR) and amplitude ratio (AR). The effects of vibrating parameters on FTR and AR are studied with the help of Full Factorial Design and analysis of variance. It is found that FTR can be increased by increasing the ratio of amplitude in normal direction to the feed and the ratio of frequency in normal direction to spindle speed, while AR will be enlarged with increase of the ratio of amplitude in feed direction to the feed and the ratio of frequency in feed direction to spindle speed. The simulation studies are the foundation for calculating cutting force, tool wear and surface roughness in 2-D VAMM and can also guide the further experiment.

Low Frequency Vibration Assisted Drilling of Aluminium Alloys

2013 ◽  
Vol 769 ◽  
pp. 131-138 ◽  
Author(s):  
Oliver Pecat ◽  
Ingo Meyer
Keyword(s):  
Cutting Force ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Low Frequency ◽  
Cutting Conditions ◽  
Machining Process ◽  
Drilling Process ◽  
Chip Shape ◽  
Vibration Drilling ◽  
Chip Breakage

In the present study the vibration drilling process of light weight materials and compound stacks has been investigated. Fiber-metal compound materials provide excellent mechanical properties which make them a major choice in lightweight applications. Especially in aircraft industry the use of multi-layer materials is significantly increased during the last few years. To join parts of dissimilar materials usually rivets or bolts are applied as fasteners. Therefore it is necessary to machine boreholes with partially very high quality requirements. Because of the different material properties the machining process of serial stacks imposes high demands to the cutting tools and requires certain process strategies. Previous investigations revealed that the bore surface can be damaged during the extraction of the hot and sharp metallic chips. Besides the risk of thermal damage the main issue lies in an erosive expansion of the borehole diameter due to the reaming of metallic chips at the borehole surface. The chip extraction can be significantly improved by low frequency assisted vibration drilling. In that case the axial tool movement is superimposed by a sinusoidal oscillation (in this case 1.5 per revolution) which is provided by the tool holder. Under certain cutting conditions this leads to a controlled chip breakage. Compared to conventional drilling the process parameters, cutting speed vc and feed f are supplemented with the amplitude A of the oscillation and the frequency f which represents the amount of vibrations per revolution of the tool. This causes radical changes to the kinematics of the process and therefore of the cutting conditions and chip formation. For a better understanding of the process a kinematic model for a two-flute cutter was developed which allows calculating the undeformed chip shape in dependency of the four cutting parameters vc, fz, A and f. The model also helps to predict whether a discontinuous cut will be achieved or not. To characterize the process and chip shape the following parameters are optionally calculated within the model: maximum chip thickness, chip radian, effective feed, feed speed at the moment of tool entrance and exit (for one chip). Experimental drilling trials in Al2024 T351 were used to evaluate the calculated parameters. The chip thickness and radian as well as the cutting time show a very good correlation to the calculations. It is interesting that the measured cutting forces are much lower compared to the theoretical values according to the Kienzle cutting force equation. Additionally it was found that the measured cutting force is strongly decreasing with an increasing cutting speed. Infrared images of the drilling process in Ti6Al4V were used to analyze the temperature close to the cutting zone and to observe the chip evacuation during the process. It was found that the cutting temperature is up to 50% lower when using vibration drilling. Furthermore it was shown that this effect is strongly dependent on the chip extraction. It is important that the chips do not stack in the drilling flute during the process. A chip breakage is facilitated by a decreasing ratio between feed and amplitude. At the same time an increasing material removal rate degrades the chip extraction even if the chips are separated. Besides the advantages of vibration drilling a major issue was found to be chipping at the cutting edges or even tool breakage. This could be avoided by a reduction of the oscillation amplitude and /or feed. Under consideration of these correlations the productivity of the drilling process and the bore hole quality in CFRP/Ti6Al4V-stacks could be significantly increased. The investigations have shown that vibration assisted drilling represents a huge opportunity, especially in the field of drilling composite materials. However further investigations are necessary to better understand this very complex process.

New Design for a Differentially Pumped Hydration Chamber for a Siemens IA

1971 ◽  
Vol 29 ◽  
pp. 44-45
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Water Vapor ◽  
Electron Diffraction ◽  
Water Vapor Pressure ◽  
Biological Materials ◽  
Thin Membrane ◽  
Reliable System ◽  
System A ◽  
Water Films ◽  
Aperture Opening

Electron microscopy and diffraction of biological materials in the hydrated state requires the construction of a chamber in which the water vapor pressure can be maintained at saturation for a given specimen temperature, while minimally affecting the normal vacuum of the remainder of the microscope column. Initial studies with chambers closed by thin membrane windows showed that at the film thicknesses required for electron diffraction at 100 KV the window failure rate was too high to give a reliable system. A single stage, differentially pumped specimen hydration chamber was constructed, consisting of two apertures (70-100μ), which eliminated the necessity of thin membrane windows. This system was used to obtain electron diffraction and electron microscopy of water droplets and thin water films. However, a period of dehydration occurred during initial pumping of the microscope column. Although rehydration occurred within five minutes, biological materials were irreversibly damaged. Another limitation of this system was that the specimen grid was clamped between the apertures, thus limiting the yield of view to the aperture opening.

Advanced TEM sample preparation techniques for submicron Si devices

1995 ◽  
Vol 53 ◽  
pp. 516-517 ◽  
Author(s):  
P. B. Basham ◽  
H. L. Tsai
Keyword(s):  
Sample Preparation ◽  
Process Development ◽  
Light Transmission ◽  
Specific Area ◽  
Turnaround Time ◽  
Small Hole ◽  
Area Of Interest ◽  
Transmission Electron ◽  
Polished Side ◽  
Preparation Techniques

The use of transmission electron microscopy (TEM) to support process development of advanced microelectronic devices is often challenged by a large amount of samples submitted from wafer fabrication areas and specific-spot analysis. Improving the TEM sample preparation techniques for a fast turnaround time is critical in order to provide a timely support for customers and improve the utilization of TEM. For the specific-area sample preparation, a technique which can be easily prepared with the least amount of effort is preferred. For these reasons, we have developed several techniques which have greatly facilitated the TEM sample preparation.For specific-area analysis, the use of a copper grid with a small hole is found to be very useful. With this small-hole grid technique, TEM sample preparation can be proceeded by well-established conventional methods. The sample is first polished to the area of interest, which is then carefully positioned inside the hole. This polished side is placed against the grid by epoxy Fig. 1 is an optical image of a TEM cross-section after dimpling to light transmission.

High-resolution electron microscopy of Cu2O surfaces

1986 ◽  
Vol 44 ◽  
pp. 396-397
Author(s):  
V. Castano ◽  
W. Krakow
Keyword(s):  
High Resolution ◽  
Natural Extension ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Initial Oxidation ◽  
System A ◽  
Resolution Electron ◽  
Surface Reconstructions ◽  
Atomic Surface ◽  
Au Thin Films

In non-UHV microscope environments atomic surface structure has been observed for flat-on for various orientations of Au thin films and edge-on for columns of atoms in small particles. The problem of oxidation of surfaces has only recently been reported from the point of view of high resolution microscopy revealing surface reconstructions for the Ag2O system. A natural extension of these initial oxidation studies is to explore other materials areas which are technologically more significant such as that of Cu2O, which will now be described.

Twin boundary structure of a Y-Ba-Cu-O superconductor

1989 ◽  
Vol 47 ◽  
pp. 168-169
Author(s):  
Yimei Zhu ◽  
Masaki Suenaga ◽  
R. L. Sabatini ◽  
Youwen Xu
Keyword(s):  
Twin Boundary ◽  
Fine Particles ◽  
Imaging Techniques ◽  
Fine Powder ◽  
Orthorhombic Phase ◽  
Boundary Structure ◽  
Crystallographic Axis ◽  
System A ◽  
High Resolution Structure ◽  
Electron Microscopes

The (110) twin structure of YBa2Cu3O7 superconductor oxide, which is formed to reduce the strain energy of the tetragonal to orthorhombic phase transformation by alternating the a-b crystallographic axis across the boundary, was extensively investigated. Up to now the structure of the twin boundary still remained unclear. In order to gain insight into the nature of the twin boundary in Y-Ba-Cu-O system, a study using electron diffraction techniques including optical and computed diffractograms, as well as high resolution structure imaging techniques with corresponding computer simulation and processing was initiated.Bulk samples of Y-Ba-Cu-O oxide were prepared as described elsewhere. TEM specimens were produced by crushing bulk samples into a fine powder, dispersing the powder in acetone, and suspending the fine particles on a holey carbon grid. The electron microscopy during this study was performed on both a JEOL 2000EX and 2000FX electron microscopes operated at 200 kV.

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