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Volume 16 (2022): Issue 1 (April 2022)

Volume 15 (2021): Issue 1 (October 2021)

Volume 14 (2021): Issue 1 (April 2021)

Volume 13 (2020): Issue 1 (October 2020)

Volume 12 (2020): Issue 1 (April 2020)

Volume 11 (2019): Issue 1 (October 2019)

Volume 10 (2019): Issue 1 (April 2019)

Volume 9 (2018): Issue 1 (October 2018)

Volume 8 (2018): Issue 1 (April 2018)

Journal Details
Format
Journal
eISSN
2601-5773
First Published
30 Dec 2018
Publication timeframe
2 times per year
Languages
English

Search

Volume 14 (2021): Issue 1 (April 2021)

Journal Details
Format
Journal
eISSN
2601-5773
First Published
30 Dec 2018
Publication timeframe
2 times per year
Languages
English

Search

12 Articles
Open Access

Applicability of Procedural Variants in Ultrasonic Testing

Published Online: 05 Aug 2021
Page range: 1 - 9

Abstract

Abstract

Ultrasonic testing (UT) is essentially the transmission of high-frequency (0.25…20 MHz) sound waves (mechanical vibration and energy) into a material, in order to interact with the macro-structural constituents of the material which reflect and/or weaken it. Ultrasonic testing – as one of the most common nondestructive material testing (NDT) methods – thanks to its many variants, is able to operate in a mobilized and highly automated fashion; it can be performed on most material types; high accuracy and reproducibility can be achieved in error detection, and it is generally enough if only one side is accessible; changes in elevation can also be verified with this method besides distance measurement, and it is also suitable for determining certain material characteristics. The present article reviews the application technology characteristic of the procedural variants.

Keywords

  • mechanical vibration
  • coupling
  • transmitter
  • receiver
  • discontinuity
  • fault signal
Open Access

The Story of a Re-Operating Windmill

Published Online: 05 Aug 2021
Page range: 10 - 17

Abstract

Abstract

Research on the history of the development of grain milling structures is a priority topic of the Department of Technical Sciences of the Transylvanian Museum Association. Quite a few publications and study volumes contain the results of the research. The present dissertation presents another grinding structure, the windmill, its reconstruction, creating a connection between the theoretical foundations and the practical implementation. Although it was built as a museum and tourist object, it is also a significant work from the point of view of technical history.

The Felsőszentiván windmill is powered by a 14-meter-diameter windmill. The mill has a two-stage accelerator gear that increases the low, non-grinding speed of the wind turbine for the rotation typical of grindstone mills.

The upper stones of a pair of grindstones rest on a vertical axis, and by raising this the gap between the stones can be adjusted. This determines the particle size of the grind. The windmill consists of three functional parts: a windmill, an accelerator gear and a grain mill made up of a pair of grindstones.

Keywords

  • windmill
  • gear transmission
  • grinding
  • grindstone pair
Open Access

Industry and Research: New Collaborative Perspectives in the Industry 4.0 Era

Published Online: 05 Aug 2021
Page range: 18 - 22

Abstract

Abstract

The paper presents some challenges of developing DIHs (Digital Innovation Hubs) based on the Industry 4.0 principles in Transylvania (Romania). DIHs have proven to be successful as knowledge transfer centers especially in information technologies, but they are still a novelty in the field of manufacturing technologies and industrial engineering in many regions. The paper presents conceptual possibilities of developing a manufacturing technology based DIH in Romania, based on cooperation among local organizations.

Keywords

  • Digital Innovation Hub
  • Industry 4.0.
  • R&D cooperation
Open Access

The Improvement of the Precision of the Archimedean Spiral Toothline Gear Cutting Mill

Published Online: 05 Aug 2021
Page range: 23 - 29

Abstract

Abstract

The precision of gears has a major influence on the quality of the transmission. If the gear cannot be finished by grinding, the precision of the generating tool becomes essential. Archimedean spiral toothline cylindrical gears are obtained by reciprocate meshing using a milling cutter built up by individual cutters, organized in groups. The profiles of edges must be realized with a minimal profile error. In order to ensure the quality and the precision of the meshed tooth surface, and also the profile constancy after re-sharpening, relief faces must be realized by a grinding relieving operation. A secondary effect of the kinematics of relieving end the spatial extent of the grinding wheel a post undercut results and this produces an inevitable profile error. The present paper discusses a possible grinding wheel setting that produces a maximum theoretical profile error under 1μm along the whole re-sharpening reserve of the cutter. The proposed setting can be realized on a classical relieving lathe.

Keywords

  • gear cutting
  • milling head
  • relieving
  • profile error
Open Access

The Conditions of Undercut By Shaping Using a Rounded Profile Gear Shaper Cutter

Published Online: 05 Aug 2021
Page range: 30 - 36

Abstract

Abstract

The present paper deals with the cases of undercut when not only the linear but the curved segment of the generatrix curve is also taken in consideration. The literature admits the approximation of the root fillet with a circular arc with a radius of 0,38 m. In this paper, instead of this approximation, the real envelope realized by the rounded rack-head is computed. In analyzing the undercut there are two classical synthetic geometrical models supporting Litvin’s general equations that describe the condition of avoiding the undercut: one for the linear and one for the rounded part of the generatrix. The scope of exact computing of the root fillet curve consists in optimizing the cutting toll tooth topland geometry to obtain the best rigidity. The numerically evaluated models allow us to conclude that profile shifting can be pushed below the undercut limits stated in the classical literature, without the appearance of the well-known fracture point on the meshed tooth profile.

Keywords

  • rack
  • profile parameters
  • meshing
  • root fillet
  • undercut
Open Access

Thermal Behaviour Analysis of Complex Joints for an Energy Efficient School Building

Published Online: 05 Aug 2021
Page range: 37 - 43

Abstract

Abstract

Energy-efficient buildings have received increasing attention in recent times as they represent a direction that promotes the objectives of a sustainable, competitive and decarbonized energy policy. In order to meet the minimum requirements of the nearly zero-energy buildings (nZEB) the thermal characteristics of the envelope play an important role. The aim of the paper is to present and analyse the thermal behaviour of complex joints for an energy efficient school building, for which the formation of thermal bridges has been reduced by applying improved geometrical and technological solutions. Since most of the thermal bridge catalogues did not provide updated details for the studied joints, numerical calculations, as two-dimensional finite elements thermal simulations, were performed to determine thermal transmittance coefficients and the U-value..

Keywords

  • energy efficiency
  • thermal bridges
  • complex joints
  • thermal transmittance coefficient
Open Access

An Analysis of Manufacturing Precision of Involute Worms Using a Kinematical Model

Published Online: 05 Aug 2021
Page range: 44 - 50

Abstract

Abstract

The manufacturing precision of involute worms constitutes a major requirement. On the one hand, the worm constitutes the input element of the worm drive; secondly, the involute helical surface is the basic surface of an involute worm-hob. This paper presents an analytic comparison between the involute surfaces obtained using theoretical equations, kinematic simulation of the cutting and the surface charged with errors. The surface error is considered the distance along the normal direction to the theoretical surface, measured between this and the surface charged with simulated manufacturing errors. The main sources of errors are considered the center-error of the edge plane, the edge profile error and deviation of the axial feed direction from the axis of the worm. The theoretical results allow us to conclude that the influence of the edge profile error is the largest. It is followed by the parallelism error between the feed direction and the axis of the worm, and finally, the center error of the tool edge.

Keywords

  • involute worm
  • profile error
  • positioning error
Open Access

Design and Wind Simulation of Steel Structures in a Parametric Environment

Published Online: 05 Aug 2021
Page range: 51 - 59

Abstract

Abstract

Nowadays, parametric design and various simulation methods are gaining ground in almost every engineering and creative profession. This paper investigates the practical applicability of the combination of these methods, by analysing a specific free-form structure with Grasshopper 3D and OpenFOAM and points out the differences between the results of a CFD simulation and the recommended methods of the Eurocode, highlighting the new perspectives that are opening up in the field of structural design, especially in the examination of wind effects.

Keywords

  • parametric structural design
  • wind simulation
  • computational fluid dynamics
Open Access

Study of Three-Point Linkage of Power Machine

Published Online: 05 Aug 2021
Page range: 60 - 64

Abstract

Abstract

The three-point linkage serves to interconnect the power machine and the suspended or semi-suspended work machine. It has a role in the operation of the machine group, in towing and in the setup of the machines. Part of the weight of the suspended machine is loaded on the driven wheels, thus increasing the adhesion weight which results in an increase in the tractive force. Understanding the operation of this equipment it is necessary for horticulture, agronomy and landscape architecture future engineers. In this thesis we model the effect of connection points of the three-point linkage on the tractive force in a specific case: that of the suspended plow.

Keywords

  • three-point linkage
  • adhesion weight force
Open Access

Investigations of Surface Qualities of Wire EDM Machined Tool Steels

Published Online: 05 Aug 2021
Page range: 65 - 70

Abstract

Abstract

In the EDM process an electrical discharge occurs between an anode (graphite or copper) and a cathode (material to be machined) in a dielectric medium. Developments in EDM technologies have opened a new path towards high-precision, more productive machining of high alloyed, high hardness and high strength steels [1]. Wire EDM offers an efficient and cost effective alternative to traditional machining in tool and component manufacturing [2]. EDM machining removes electrically conductive material with rapid and repetitive spark emissions using a dielectric fluid. As a result, the surface of the raw material is subject to erosion. The quality of the machined surface depends to a large extent on the parameters of the machining technology [3]. In the testing experiments, wire EDM machining was performed on two tool steel grades using different machining parameters. After each machining step, hardness and roughness tests were performed on the surface of the workpiece. Scanning electron microscopy was performed on the machined surface. The tests confirmed that the surface quality of the tools is significantly influenced by the parameters set during the EDM. The change of parameters was achieved by performing multiple cutting threads. By using the multiple cutting thread, tools with favourable surface roughness have been produced for tool steels with a high hardness of quenched and tempered heat treatment state.

Keywords

  • wire EDM
  • tool steel
  • surface roughness
  • scanning electron microscopy.
Open Access

Reliability Question of New Material Used in Vehicle Engineering

Published Online: 05 Aug 2021
Page range: 71 - 76

Abstract

Abstract

In-vehicle engineering, several types of materials can be used to build vehicles of different sizes and for different uses. Traditionally those materials can be iron, aluminium, steel, rubber, glass, copper, leather, and others. These materials have been in constant development over the years, and this development has accelerated during the last ten years as manufacturers strive to compete on the issue of reliability of these new innovative materials. Reliability requires the production of materials with minimal (or well-known) variations in properties or dimensions. Parts made from these materials must be manufactured using processes that have also been proven to be reliable. This aim of this paper is to explain how reliability criteria can only be obtained if there are means of control suited to the most used materials (metals and polymers).

Keywords

  • reliability
  • automotive manufacture
  • vehicle engineering
  • metals
Open Access

Control of an Electric Vehicle Hybrid Energy Storage System

Published Online: 05 Aug 2021
Page range: 77 - 88

Abstract

Abstract

In electric vehicles battery life can be prolonged by using hybrid energy storage systems (HESS ), which combine high energy density batteries with supercapacitors, characterized by high power density. This paper deals with the control of electronic power converters from an active parallel HESS. The load of the HESS is the electrical motor drive of an electric vehicle. The interfaces between the DC-link and the power sources are four-phase bidirectional DC-DC converters driven in current control mode, based on the current references supplied by an active parallel HESS power distribution algorithm. We present a rule-based fuzzy energy management algorithm for a HESS powered electric vehicle and its simulation in MATLAB/Simulink® environment using the Quasi-Static Simulation (QSS ) and Fuzzy Logic toolboxes. Also, simulation results in driving and regenerative braking operation modes of the electric vehicle are presented.

Keywords

  • hybrid energy storage systems
  • energy management algorithm
  • bidirectional 4-phase DC-DC converter
  • power distribution control structure
12 Articles
Open Access

Applicability of Procedural Variants in Ultrasonic Testing

Published Online: 05 Aug 2021
Page range: 1 - 9

Abstract

Abstract

Ultrasonic testing (UT) is essentially the transmission of high-frequency (0.25…20 MHz) sound waves (mechanical vibration and energy) into a material, in order to interact with the macro-structural constituents of the material which reflect and/or weaken it. Ultrasonic testing – as one of the most common nondestructive material testing (NDT) methods – thanks to its many variants, is able to operate in a mobilized and highly automated fashion; it can be performed on most material types; high accuracy and reproducibility can be achieved in error detection, and it is generally enough if only one side is accessible; changes in elevation can also be verified with this method besides distance measurement, and it is also suitable for determining certain material characteristics. The present article reviews the application technology characteristic of the procedural variants.

Keywords

  • mechanical vibration
  • coupling
  • transmitter
  • receiver
  • discontinuity
  • fault signal
Open Access

The Story of a Re-Operating Windmill

Published Online: 05 Aug 2021
Page range: 10 - 17

Abstract

Abstract

Research on the history of the development of grain milling structures is a priority topic of the Department of Technical Sciences of the Transylvanian Museum Association. Quite a few publications and study volumes contain the results of the research. The present dissertation presents another grinding structure, the windmill, its reconstruction, creating a connection between the theoretical foundations and the practical implementation. Although it was built as a museum and tourist object, it is also a significant work from the point of view of technical history.

The Felsőszentiván windmill is powered by a 14-meter-diameter windmill. The mill has a two-stage accelerator gear that increases the low, non-grinding speed of the wind turbine for the rotation typical of grindstone mills.

The upper stones of a pair of grindstones rest on a vertical axis, and by raising this the gap between the stones can be adjusted. This determines the particle size of the grind. The windmill consists of three functional parts: a windmill, an accelerator gear and a grain mill made up of a pair of grindstones.

Keywords

  • windmill
  • gear transmission
  • grinding
  • grindstone pair
Open Access

Industry and Research: New Collaborative Perspectives in the Industry 4.0 Era

Published Online: 05 Aug 2021
Page range: 18 - 22

Abstract

Abstract

The paper presents some challenges of developing DIHs (Digital Innovation Hubs) based on the Industry 4.0 principles in Transylvania (Romania). DIHs have proven to be successful as knowledge transfer centers especially in information technologies, but they are still a novelty in the field of manufacturing technologies and industrial engineering in many regions. The paper presents conceptual possibilities of developing a manufacturing technology based DIH in Romania, based on cooperation among local organizations.

Keywords

  • Digital Innovation Hub
  • Industry 4.0.
  • R&D cooperation
Open Access

The Improvement of the Precision of the Archimedean Spiral Toothline Gear Cutting Mill

Published Online: 05 Aug 2021
Page range: 23 - 29

Abstract

Abstract

The precision of gears has a major influence on the quality of the transmission. If the gear cannot be finished by grinding, the precision of the generating tool becomes essential. Archimedean spiral toothline cylindrical gears are obtained by reciprocate meshing using a milling cutter built up by individual cutters, organized in groups. The profiles of edges must be realized with a minimal profile error. In order to ensure the quality and the precision of the meshed tooth surface, and also the profile constancy after re-sharpening, relief faces must be realized by a grinding relieving operation. A secondary effect of the kinematics of relieving end the spatial extent of the grinding wheel a post undercut results and this produces an inevitable profile error. The present paper discusses a possible grinding wheel setting that produces a maximum theoretical profile error under 1μm along the whole re-sharpening reserve of the cutter. The proposed setting can be realized on a classical relieving lathe.

Keywords

  • gear cutting
  • milling head
  • relieving
  • profile error
Open Access

The Conditions of Undercut By Shaping Using a Rounded Profile Gear Shaper Cutter

Published Online: 05 Aug 2021
Page range: 30 - 36

Abstract

Abstract

The present paper deals with the cases of undercut when not only the linear but the curved segment of the generatrix curve is also taken in consideration. The literature admits the approximation of the root fillet with a circular arc with a radius of 0,38 m. In this paper, instead of this approximation, the real envelope realized by the rounded rack-head is computed. In analyzing the undercut there are two classical synthetic geometrical models supporting Litvin’s general equations that describe the condition of avoiding the undercut: one for the linear and one for the rounded part of the generatrix. The scope of exact computing of the root fillet curve consists in optimizing the cutting toll tooth topland geometry to obtain the best rigidity. The numerically evaluated models allow us to conclude that profile shifting can be pushed below the undercut limits stated in the classical literature, without the appearance of the well-known fracture point on the meshed tooth profile.

Keywords

  • rack
  • profile parameters
  • meshing
  • root fillet
  • undercut
Open Access

Thermal Behaviour Analysis of Complex Joints for an Energy Efficient School Building

Published Online: 05 Aug 2021
Page range: 37 - 43

Abstract

Abstract

Energy-efficient buildings have received increasing attention in recent times as they represent a direction that promotes the objectives of a sustainable, competitive and decarbonized energy policy. In order to meet the minimum requirements of the nearly zero-energy buildings (nZEB) the thermal characteristics of the envelope play an important role. The aim of the paper is to present and analyse the thermal behaviour of complex joints for an energy efficient school building, for which the formation of thermal bridges has been reduced by applying improved geometrical and technological solutions. Since most of the thermal bridge catalogues did not provide updated details for the studied joints, numerical calculations, as two-dimensional finite elements thermal simulations, were performed to determine thermal transmittance coefficients and the U-value..

Keywords

  • energy efficiency
  • thermal bridges
  • complex joints
  • thermal transmittance coefficient
Open Access

An Analysis of Manufacturing Precision of Involute Worms Using a Kinematical Model

Published Online: 05 Aug 2021
Page range: 44 - 50

Abstract

Abstract

The manufacturing precision of involute worms constitutes a major requirement. On the one hand, the worm constitutes the input element of the worm drive; secondly, the involute helical surface is the basic surface of an involute worm-hob. This paper presents an analytic comparison between the involute surfaces obtained using theoretical equations, kinematic simulation of the cutting and the surface charged with errors. The surface error is considered the distance along the normal direction to the theoretical surface, measured between this and the surface charged with simulated manufacturing errors. The main sources of errors are considered the center-error of the edge plane, the edge profile error and deviation of the axial feed direction from the axis of the worm. The theoretical results allow us to conclude that the influence of the edge profile error is the largest. It is followed by the parallelism error between the feed direction and the axis of the worm, and finally, the center error of the tool edge.

Keywords

  • involute worm
  • profile error
  • positioning error
Open Access

Design and Wind Simulation of Steel Structures in a Parametric Environment

Published Online: 05 Aug 2021
Page range: 51 - 59

Abstract

Abstract

Nowadays, parametric design and various simulation methods are gaining ground in almost every engineering and creative profession. This paper investigates the practical applicability of the combination of these methods, by analysing a specific free-form structure with Grasshopper 3D and OpenFOAM and points out the differences between the results of a CFD simulation and the recommended methods of the Eurocode, highlighting the new perspectives that are opening up in the field of structural design, especially in the examination of wind effects.

Keywords

  • parametric structural design
  • wind simulation
  • computational fluid dynamics
Open Access

Study of Three-Point Linkage of Power Machine

Published Online: 05 Aug 2021
Page range: 60 - 64

Abstract

Abstract

The three-point linkage serves to interconnect the power machine and the suspended or semi-suspended work machine. It has a role in the operation of the machine group, in towing and in the setup of the machines. Part of the weight of the suspended machine is loaded on the driven wheels, thus increasing the adhesion weight which results in an increase in the tractive force. Understanding the operation of this equipment it is necessary for horticulture, agronomy and landscape architecture future engineers. In this thesis we model the effect of connection points of the three-point linkage on the tractive force in a specific case: that of the suspended plow.

Keywords

  • three-point linkage
  • adhesion weight force
Open Access

Investigations of Surface Qualities of Wire EDM Machined Tool Steels

Published Online: 05 Aug 2021
Page range: 65 - 70

Abstract

Abstract

In the EDM process an electrical discharge occurs between an anode (graphite or copper) and a cathode (material to be machined) in a dielectric medium. Developments in EDM technologies have opened a new path towards high-precision, more productive machining of high alloyed, high hardness and high strength steels [1]. Wire EDM offers an efficient and cost effective alternative to traditional machining in tool and component manufacturing [2]. EDM machining removes electrically conductive material with rapid and repetitive spark emissions using a dielectric fluid. As a result, the surface of the raw material is subject to erosion. The quality of the machined surface depends to a large extent on the parameters of the machining technology [3]. In the testing experiments, wire EDM machining was performed on two tool steel grades using different machining parameters. After each machining step, hardness and roughness tests were performed on the surface of the workpiece. Scanning electron microscopy was performed on the machined surface. The tests confirmed that the surface quality of the tools is significantly influenced by the parameters set during the EDM. The change of parameters was achieved by performing multiple cutting threads. By using the multiple cutting thread, tools with favourable surface roughness have been produced for tool steels with a high hardness of quenched and tempered heat treatment state.

Keywords

  • wire EDM
  • tool steel
  • surface roughness
  • scanning electron microscopy.
Open Access

Reliability Question of New Material Used in Vehicle Engineering

Published Online: 05 Aug 2021
Page range: 71 - 76

Abstract

Abstract

In-vehicle engineering, several types of materials can be used to build vehicles of different sizes and for different uses. Traditionally those materials can be iron, aluminium, steel, rubber, glass, copper, leather, and others. These materials have been in constant development over the years, and this development has accelerated during the last ten years as manufacturers strive to compete on the issue of reliability of these new innovative materials. Reliability requires the production of materials with minimal (or well-known) variations in properties or dimensions. Parts made from these materials must be manufactured using processes that have also been proven to be reliable. This aim of this paper is to explain how reliability criteria can only be obtained if there are means of control suited to the most used materials (metals and polymers).

Keywords

  • reliability
  • automotive manufacture
  • vehicle engineering
  • metals
Open Access

Control of an Electric Vehicle Hybrid Energy Storage System

Published Online: 05 Aug 2021
Page range: 77 - 88

Abstract

Abstract

In electric vehicles battery life can be prolonged by using hybrid energy storage systems (HESS ), which combine high energy density batteries with supercapacitors, characterized by high power density. This paper deals with the control of electronic power converters from an active parallel HESS. The load of the HESS is the electrical motor drive of an electric vehicle. The interfaces between the DC-link and the power sources are four-phase bidirectional DC-DC converters driven in current control mode, based on the current references supplied by an active parallel HESS power distribution algorithm. We present a rule-based fuzzy energy management algorithm for a HESS powered electric vehicle and its simulation in MATLAB/Simulink® environment using the Quasi-Static Simulation (QSS ) and Fuzzy Logic toolboxes. Also, simulation results in driving and regenerative braking operation modes of the electric vehicle are presented.

Keywords

  • hybrid energy storage systems
  • energy management algorithm
  • bidirectional 4-phase DC-DC converter
  • power distribution control structure

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