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Journal PROCEEDINGS IN MANUFACTURING SYSTEMS |
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ISSN 2343–7472 ISSN-L 2067-9238 |
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Journal PROCEEDINGS IN MANUFACTURING SYSTEMS
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Volume 17, Issue 1, 2022 · George-Christopher VOSNIAKOS, Ioannis PIERATOS, Theodore MITROPOULOS,
Panagiotis AVRAMPOS, Preliminary investigation on undamped open loop control
of a polishing jig for machining centres · Georgios SOTIRCHOS, George-Christopher VOSNIAKOS, Development of a programmable work-holding fixture for
laser welding of solar absorber sheets · Bruno RĂDULESCU, Laurențiu SLĂTINEANU, Mara RĂDULESCU,
Adelina HRIȚUC, Surface roughness when turning one-sheeted revolution
hyperboloid surface Cloud-based
system for surface roughness control in end-milling
 View full textPreliminary investigation on undamped open
loop control of a polishing jig for machining centres George-Christopher
VOSNIAKOS1,*, Ioannis PIERATOS2, Theodore MITROPOULOS3,
Panagiotis AVRAMPOS4 1) Prof., Manufacturing Technology Laboratory, School of Mechanical
Engineering, National Technical University of Athens, Athens, Greece 2) MSc graduate student, School of Mechanical Engineering, National
Technical University of Athens, Athens, Greece 3) MSc graduate student, School of Mechanical Engineering, National
Technical University of Athens, Athens, Greece 4) PhD Student, School of Mechanical Engineering, National Technical
University of Athens, Athens, Greece Abstract: In finishing of surfaces with
variable curvature the normal force must vary to control contact pressure. In
this work, a special jig that provided passive control when used on machining
centers was redesigned in order to support active force control. This was
achieved indirectly by controlling displacement of the spring – loaded
finishing tool by means of a stepper motor and a lead screw. An open loop
control system was implemented through a microcontroller and a stepper motor
driver. In order to synchronize the movement of the tool along its trajectory
with the spring displacement as appropriate, the necessary communication
between the microcontroller and the CNC controller was implemented through a
serial port. No damping has been used initially in order to investigate
adequacy of friction forces to dampen oscillations. Experiments were carried
out on a steel flat surface on a 3 axis machining center with different tools
and polishing paste grit sizes. Experiments proved the ability of the open
loop controller to follow desirable force variation patterns or two different
types, namely random and sinusoidal / periodic. In both cases the mean force
variation was close enough to the intended nominal one, but strong force
deviations were present pointing to the need to use external damping. Key
words: Polishing, Active Force Control, Machining
Center, Polishing Jig.
Development of a programmable work-holding
fixture for laser welding of solar absorber sheets Georgios
SOTIRCHOS1, George-Christopher VOSNIAKOS2,* 1) MSc graduate student, School of Mechanical Engineering, National
Technical University of Athens, Athens, Greece 2) Prof., Manufacturing Technology Laboratory, School of Mechanical
Engineering, National Technical University of Athens, Athens, Greece. Abstract: Production of solar absorbers
in significant quantities relies on laser welding of large, thin, aluminum
sheets. Dealing with multiple product variants requires setup time
minimization of the laser welding machine while preserving product quality. A
mechatronic work-holding fixture was developed as a solution to this problem.
The ultimate aim is to replace the manual setup method completely. The latter
was documented first, accompanied by user requirements and resulting
technical specifications including geometric limits and range of motion. The
proposed design was developed and optimized using CAD simulation. In
addition, a software interface was designed to allow fixture configuration
based on just the necessary dimensions of solar absorber variants. Fixture
tests proved achievement of desired precision and substantial reduction of
setup duration. Key
words: work-holding, programmable fixture,
microcontroller, laser welding, sheet metal.
Surface
roughness when turning one-sheeted revolution hyperboloid surface Bruno
RĂDULESCU1, Laurențiu SLĂTINEANU2, Mara
RĂDULESCU1, Adelina HRIȚUC2,* 1) Lecturer, Ph.D., Department of Machine Tools and Tools, “Gheorghe Asachi”
Technical University of Iași, România 3) Lecturer, Ph.D., Department of Machine Tools and Tools, “Gheorghe
Asachi” Technical University of Iași, România 4) Ph.D. Student, Department of Machine Manufacturing Technology,
“Gheorghe Asachi” Technical University of Iași, România Abstract: There are situations in industrial
practice when parts that must have a one-sheeted revolution hyperboloid
surface are necessary. Turning and milling are used as roughing processing
for such surfaces. The emergence and development of numerically controlled
lathes and milling machines have facilitated the machining of hyperboloidal
surfaces when the mathematical function that defines the hyperbola in the
axial plane of the hyperboloidal surface is available. In the case of turning
and when the tool corner moves along a path in the shape of a hyperbola
segment, it is found that there is a variation of the cutting speed along the
path of the tool corner. This variation of the cutting speed could lead to a
continuous change, within certain limits, of the values of some roughness
parameters, such as, for example, the arithmetic mean deviation Ra of the assessed
profile. To further investigate this variation in the value of the roughness
parameter Ra when changing the cutting speed, an experimental research
program was designed according to the requirements of a full factorial
experiment with three independent variables and two levels of variation. As
the independent variables, the corner radius of the lathe tool, the
longitudinal feed rate, and the cutting speed were taken into account.
Experimental tests were performed on aluminum test samples. The mathematical
processing of the experimental results confirmed the variation of the size of
the roughness parameter Ra along the hyperboloidal surface made by turning,
mainly due to the change in the cutting speed. Among the input factors
considered, it was found that the strongest influence on the size of the
roughness parameter Ra is exerted by the corner radius of the lathe tool,
followed by the size of the longitudinal feed. Key
words: hyperboloidal surface, turning, surface
roughness, corner radius, feed, cutting speed, empirical mathematical model.
Prediction
of surface roughness in milling based on acoustic signals using different
types of intelligent algorithms Goran
MUNĐAR1,*, Uroš ŽUPERL2 1) MSc Eng., Researcher, Laboratory
for Mechatronics, Faculty of Mechanical Engineering, University of Maribor,
Maribor, Slovenia 2) Assoc. Prof., Researcher, Laboratory for Mechatronics, Faculty of Mechanical Engineering,
University of Maribor, Maribor, Slovenia Abstract: Surface
roughness is playing very important role in the performance of finished part.
Roughness measurements are typically done off-line after the part has already
been machined, but recently the focus has changed to online monitoring.
Through advancements in the fields of computers and sensors, it is now
possible to measure and control the machining processes. With the advancement
of artificial intelligence and intelligent algorithms new system can be
build, that can describe complex, non-linear, multi-variant machining
processes. The main focus of this paper is to develop three different
prediction models for predicting surface roughness of machined parts during
milling. Prediction models will be able to predict surface roughness based on
four inputs: feed rate, spindle speed, depth of cut and vibration. For the
development of different intelligent prediction models MATLAB software tool
will be used. Prediction models will be based on artificial neural networks
(ANN) and adaptive neuro-fuzzy inference system (ANFIS). The results of developed
prediction models will be compared to statistical regression analysis results
and to experimental results. Key
words: Machining, Milling process, Surface roughness,
Artificial neural networks, ANFIS, Online monitoring system.
Cloud-based system
for surface roughness control in end-milling Uros ZUPERL,* 1, Miha KOVACIC2 1)
Assoc. Prof., University of Maribor, Faculty of Mechanical Engineering,
Maribor, Slovenia 2) Assoc.
Prof., Štore Steel, Štore, Slovenia, University of
Ljubljana, Faculty of Mechanical Engineering, Slovenia Abstract: The main purpose of this article is to
present the structure of the cloud-based platform for controlling the
roughness of the machined surface. The developed system connects computing
and service resources in the cloud with physical resources in the tool shop.
The connection of cloud resources and physical elements was the basis for the
formation of the two-stage cyber-physical roughness control system (CPrCS)
for end-milling. The two-stage CPrCS with its ability to
connect sensors and actuators to the cyber world is designed to maintain a
constant roughness of the treated surface by digitally adjusting the cutting
conditions. CPrCS with surface roughness control via cloud technologies
provides a new way to identify and eliminate defects on the machined surface
during the machining process. The physical part of
the CPrCS system combines a machine tool, piezoelectric sensor, and industrial computer to capture and transfer obtained
data to the IoT router in the cloud. The cloud system receives information
from the sensor, processes the information, performs edge computing
operations, analyses, and models surface roughness data, monitors the
process, visualizes the data and finally makes decisions about the necessary
correction of machining parameters. An artificial neural network (ANN) is
used to model and predict the surface roughness accurately. The ratios
between the measured cutting forces, the cutting conditions and the actual
surface roughness of the machined surface were determined using ANN. In the
future, the feasibility of the in-process surface quality control through
cloud technologies will be tested with additional experiments. Key words: machining, end milling, cloud technologies,
surface roughness, control.
Electronic mail: orgcom@icmas.eu |
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