Determining the dimensions of the plane semifinished materials for bent parts suing LabView applications.
Savu, Tom ; Abaza, Bogdan ; Spanu, Paulina 等
1. INTRODUCTION
The special preoccupation of researchers in finding new solutions
to improve the technologies for the processing of the products obtained
through cold plastic deformation procedures are justified by the
increase in the ever grater weight of usage of such products in all
industrial fields. The time allowed to designing of the processing
technology can be significantly shortened, if various "designing
tools" are employed, which are simple to use and, at the same time,
capable to ensure high speed and precision. The applications developed
with LabView graphic programming language satisfy the requirements of
all the engineers and researchers in the field and do not necessary need
them to have software programming knowledge, thus ensuring an easy to
use interface. Applications developed with LabView are used in research
and development activities and are made available to students and
teachers over the E-Learning platform of the Faculty of Technological
System Engineering and Management, in the form of executable files, so
that each E-Learning user may use these "design tools" without
the LabView software installed on their PC.
2. LABVIEW APPLICATIONS FOR CALCULATING THE DIMENSIONS OF PLANE
SEMIFINISHED MATERIAL AT BENDING
Bending is the process of cold plastic deformation without
intentional modification of the thickness of the material consists of
bending the plane semifinished around certain rectilinear edges (Braha
et al., 2003).
The analysis of a part technologiticy in terms of its shape and
technical conditions implies the determination of the shape and
dimensions of the plane semifinished material of which the part is to be
executed. For bent parts with bending radius other than zero, the length
of the plane semifinished is equal with the length of the neutral layer
(the layer whose shape changes, but whose length remains constant) is
determined with the formula 1 (Sindila, 2001):
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (1)
where:
L--unfolded length of the part;
[l.sub.i]--length of rectilinear portions of the neutral layer;
l[[phi].sub.i]--length o neutral layer over the bent portions of
the part, determined with the formula 2 (Sindila, 2007):
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (2)
where:
[[phi].sub.i]--bending angle;
[r.sub.i]--internal bending radius;
x--neutral layer displacement coefficient;
g--part thickness.
These apparently simple calculation formulas need precise calculus,
as they are specific for each type of part that can be manufactured
through bending. An application developed with LabView graphic
programming language, to be made available to users in the form of an
executable file, will solve this problem, regardless of shapes and
dimensions of the parts, facilitating the attaining of a high level of
precision in a very short time. The graphic programming environment
LabView is used both for the monitoring and control of industrial
processes, and for specific activities in the academic and research
environment, offering special benefits compared to traditional
programming languages.
The graphic application in LabView used to determine the dimensions
of the plane semifinished for parts obtained through bending is made of
two components: the user interface (front panel) and the block diagram where the logic of the applications was described using icons and
connection threads.
Using the elements on the panel, the user sends input data to the
programme and then displays the output data resulting from running the
programme, as indicator elements (figure 1).
[FIGURE 1 OMITTED]
To determine the dimensions of the plane semifinished, the user
will follow five steps:
* step 1. in the numerical control element, specify the value of a
rectilinear portion in mm. By pressing a Boolean type of command
element, the numerical value of the rectilinear portion will be added,
so that it may be visualized, in the List box type of element. Depending
on the part type, the user may introduce as many values as are needed.
If the user introduces a wrong or useless value, the user has the
possibility to eliminate it from the list and exclude it from the size
calculation, by selecting the value concerned and then pressing the
delete button;
* step 2. using control elements similar with those described in
step 1, the user specifies the value of the angles of the bent portions.
He may also add an unlimited angle values and delete any wrong ones.
Virtually, by running the application the user will generate a string of
numerical values to be taken into account when calculating the
dimensions according to formula 1;
* step 3. the user specifies the values of the bend radiuses
corresponding to the bent portions, and will have the possibility to
visualize the values introduced and to delete the wrong ones;
* step 4: user specifies the thickness of the material. Depending
on thickness and the value of the bending radiuses the software will
calculate, for each bent portion, the relative radius.
* Step 5. in the numerical control element, the user specified the
values of the displacement coefficient x, according to the values
displayed in the indicator element of Multicolonlist box type, as
recommended by the specialized literature.
After running the application, the numerical indicator element will
display the value of the length of the plane semifinished material,
expressed in millimeters.
The diagram is the window in which the user has opened the
algorithm based on which the application will make the calculations and
lines of reasoning as are necessary for processing the information
(figure 2).
The application for the determination of plane semifinished
material's dimensions uses the "structure case", which is
a Wile type of repetitive structure, driven by the Stop button, as well
as functions for converting numerical type of data into text type of
data, functions for converting text data into numerical data, property
nodes for Listbox type of elements with Item Names property, functions
that operate with values of numerical values string type such as Build
Array, Delete from Array, Add Array Elements, functions performing
simple arithmetical operations such as Divide, Compound Arithmetic, and
numerical and Array type of constants.
[FIGURE 2 OMITTED]
3. ACCESSING THE APPLICATION OVER THE INTERNET
Apart from being used as a standalone application, the VI can be
embedded in a HTML page to be remotely accessed over the Internet. To
allow the users to access the remote application, the VI has to be open
on the server where the HTML page is hosted and the LabView Web Server
has to be enabled (figure 3).
[FIGURE 3 OMITTED]
If only one user is allowed to have the application's control,
the feature can be enabled on the LabView Web Server and the embedded
application can be used only after the control is requested and granted
(figure 4).
[FIGURE 4 OMITTED]
4. CONCLUSION
This application made in the graphic programming environment
LabView may be successfully used to improve the design activities of the
cold plastic deformation technologies. Using this tool, which is
available on the E-learning platform of the IMST faculty, users can
determine the dimensions of the plane semifinished with high precision,
following only five steps, for any type of parts without be necessary
mathematical calculations laborious.
5. REFERENCES
Braha, V.; Naga^, Gh. & Negoescu, F. (2003) Cold pressing
technology, Publisher ESD, ISBN, Iasi, Romania
Sindila, G. (2001). Manufacturing technologies by cold pressing,
Publisher BREN, ISBN, Bucharest, Romania
Sindila, G. (2007). Processing technology design by plastic
deformation, Publisher BREN, ISBN, Romania
*** (2010) http://www.ni.com--National Instruments, Accessed on:
2010-07-10
*** (2010) http://www.ctamn.pub.ro--Advanced Technology Center for
New Materials, Accessed on: 2010-06-08
