Creation of Computer Aided Manufacturing software from Computer

Creation of Computer
Aided Manufacturing
software from Computer
Aided Design software
in the milling process
JUAN CARLOS CARRASCO GARCÍA*
Abstract
The purpose of this paper is to
describe a new Graphical User Interface (GUI) for Design and Computer
Aided Manufacturing (CAD/CAM)
applications for academic context uses.
This application,created by the autor of
this paper, is developed for automatic
generation of Computer Numerical
Control (CNC) code of two dimensional drawing created in the commercial
software Autocad and using the Visual
Basic programming language.
In production environments, the machining of complex parts such as molds
and die cast that requires high production
rates and quality are tested before they
are manufactured using CAD/CAM
applications, where numerical control is
coded automatically and is transmitted to
the milling machine. These applications
are characterized by high accuracy.
The intuitive GUI proposed in this
work is an easy to use interface that
transforms two dimensional drawing
7$8!&%)+%5#!%('9(')!5$':%;<59=;>%?@!%
(*)
Grupo de Investigación IMTEF. Programa de Ingeniería Mecánica. Universidad Autónoma del Caribe. Barranquilla, Colombia. E-mail:
[email protected].
Este documento se ha construido a partir de la ponencia del mismo nombre presentada por los autores en el “I Congreso Internacional de Ingeniería
Mecatrónica y Automatización”, organizado por el Programa de Ingeniería Mecatrónica de la Facultad de Ingeniería de la Universidad Autónoma
de Occidente, con el apoyo del Capítulo ACOFI de los programas de Ingeniería Mecatrónica y de Automatización. El documento es inédito.
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81
Creation of Computer Aided Manufacturing software from
Computer Aided Design software in the milling process
Juan Carlos Carrasco García
!M5!+5)9+%>H %)+59%$%?@!%J9'C$5%5#$5%"$+%F!%
used directly in a Fanuc control installed in
a Benchman milling CNC machine.
Keywords: CNC, CAM, CAD/CAM,
AutoCAD, manufacturing, milling, computer numerical control.
1. Introduction
At present most metalworking projects are
drawn up and tested prior to manufacture, supported by powerful computational tools Design
and Computer Aided Manufacturing CAD/
CAM. This technology is used in many machining processes with or without metal removal in
the manufacture of complex parts, molds, dies
and prototypes that require a high dimensional
accuracy and quality of manufacture. There are
a wide range of CAD/CAM softwares in which
pieces are drawn, the machining is simulated
and is generated automatically the CNC code to
transmitting it to a machine for subsequent machining. As a reference of this kind of software,
A!% "$+% ?+&% B$75!'"$CD% E9F% =;>/=;BD% GH%
CAD/CAM (Carrasco, 2006). These applications
are very effective for machining by computer.
The following is an example of a small CNC
program that is transmitted to the CNC machine
to mechanizing the model (CNC Software, 1998;
Carrasco, 2001).
G90 G71 M3 S1200
G0 X0 Y0G1 Z-5 F50
G1 X10.0 Y10 F100
G2 X 15 Y15 R 5
G1 Y30
G1 X0 Y0
G0 Z2
M5
There are CAD software such as Autocad,
that allow to design the model and save the
&'$A)+I%)+%>H %J9'C$5%%K>'$A)+I%LM"#$+I!%?@!%
format), which is a sequence of ASCII values
J'9C%A#!'!%)5%"$+%9F5$)+%5#!%C9&!@N7%"#$'$"5!ristics such as the coordinates, radius, angles,
lengths, layers, colors, etc. AutoCAD was chosen
because is extensively used in academia and in
the industry. Furthermore AutoCAD allows to
save in ASCII format the coordinates and characteristics of the entities drawn (Ochoa, 2006).
M30
The information of the entities in the DXF
?@!%!M5!+7)9+%"$+%F!%9F5$)+!&%F:%('9I'$CC)+I%
software such as Visual Basic and convert this
information into codes Computer Numerical
Controlled (CNC) codes, for simulation and
milling of the workpiece.
G0: Lineal interpolation with fast movement
The CNC program is a set of codes represen5)+I%9'&!'7%I)8!+%59%5#!%C$"#)+!N7%C98!C!+57D%
such as the movement of the tool in the XYZ
axis, the spindle rotation speed, written in a
special language (code) composed of letters and
numbers. The numerical control (NC) interprets
5#!%('9I'$CN7%)+75'<"5)9+7D%$+&%5#!:%$'!%"9+8!'-
82
ted into signals that moves the devices of the
machine. This program can be obtained in two
ways: through manual programming, in this case,
coordinates are calculated manually and written
in a CAM software from which it transmits to the
control. On the other hand, it could be obtained
through a CAD/CAM software, where the part is
drawn on the computer, the simulation of mechanizing is done and allow to get ‘automatically’
the CNC program (Ochoa, 2006; Pacheco, 2001).
Here:
G90: Absolute programming
G71: Units in millimeters
M3: Spindle ON
M5: Spindle OFF
S: Revolutions/Minute
G1: Lineal interpolation with feed rate
G2: Clockwise circular interpolation
M30: End program
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displacement.
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Creation of Computer Aided Manufacturing software from
Computer Aided Design software in the milling process
Juan Carlos Carrasco García
2. Instructions of programming and use of
software
Initially the bidimensional sketch of the piece
is drawn in AutoCAD, then extract the coordinates of the displacement of the tool into the work
piece to be milled. These procedures are detailed
in the following 3 steps:
4%
Drawing of the work piece and creation of
the toolpaths mechanizing in AutoCAD.
4%
Conversion of coordinates to Numerical
Control (NC) codes.
4%
Use of AutoCNC Mill software and its
connection with the software Benchman
for milling.
4%
Milling the parts.
the hatch 4 in the D1 layer between the contours
of PERIFERIA and the rectangle of the stock,
that hatch should be selected as horizontal lines
and spacing line equal to or less than 80% of the
diameter of the cutter mill.
Select the D1 layer entities, ungroup them using
the command Modify/Explode (Carrasco, 2005).
S$8!%5#!%?@!%A)5#%$%>H %!M5!+7)9+%F:%7!@!"5)+I%S$8!%;7%"9CC$+&%666%$+&%7!@!"5)+I%?@!%5:(!%%
AutoCAD 2004 DXF (*.Dxf).
Figure 1. Drawing of the machining path in AutoCAD
(units: Millimeters)
2. 1 Drawing of the work piece and creation of the
toolpaths mechanizing in AutoCAD
Below is how to get the Toolpath of milling on the AutoCAD taking into account the
recommendations of (Ochoa, 2006; Pacheco,
200-R%S$'C$D%-TTTR%U)+%V%U)<D%-TT.R%O9I9'!7%
V%W5!'9D%2003X,
Create 4 layers of drawing named D1, A1,
PERIFERIA and PIEZA.
D1:%Y$C!%9J%5#!%@$:!'%9J%5#!%?'75%'9<I#)+I%
mill (if more roughing create layers D2, D3,
etc.).
Source: by the author (drawing done in Autocad V2012© software).
O#!%>H %?@!%#$7%5#!%)+J9'C$5)9+%$F9<5%@)+!7%
and arcs present in the drawing as follows:
A1:%Y$C!%9J%5#!%@$:!'%9J%5#!%?'75%?+)7#)+I%
C)@@% K)J% C9'!% ?+)7#)+I% "'!$5!7% @$:!'7%;2D%
A3, etc.).
For roughing lines:
PERIFERIA: Name of the layer for the
roughing limit.
AcDbEntity
PIEZA: Name of the layer for the final
drawing piece.
100
Draw a rectangle for the stock in the point 0.0
on the layer named "0". See Figure 1.
10
Draw the piece 1 in the PIEZA layer (the
length units are in millimeters). Convert the piece
into a polyline using the command PEDIT AutoCAD (Pacheco, 2001), in the A1 layer create an
equidistant contour of the part 1 with a distance
equal to the radius (r) of the mill, generate in
the PERIFERIA layer the equidistant 3 of the
work piece 1 equal to the sum of the oversize
J9'%?+)7#)+I%K$X%$+&%5#!%C)@@%'$&)<7%K$%Z%'XD%"'!$5!%
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D1
: Name of the layer
AcDbLine : Type of entity, in this case a line.
136.65 : (Xi) X coordinate of line start point
20
136.91 : (Yi) Y coordinate of line start point
30
0.0 : (ZI) Z coordinate of line start point
11
83
Juan Carlos Carrasco García
192.92 : (Xf) X coordinate of the endpoint
of the line
Creation of Computer Aided Manufacturing software from
Computer Aided Design software in the milling process
cutter mill, approaching distance, and diameter
of the cutter mill.
31
Then in the AutoCNC Mill, taking into
account the above coordinates and parameters,
the piece automatically was drawn. Using the
PRINT command, proceed to the generation of
Numerical Control codes (NC).
0.0 :
(Zf), Z coordinate of the endpoint
of the line
For example to generate the codes for an
anti-clockwise arc was programmed as follows:
21
136.91 : (Yf) Y coordinate of the endpoint
of the line
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\')+5%b%2D%cd3c%V%cHc%V%G$@%KHJX%V%c;Y>c%
V%G$@%KPJX%V%c^c%V%G$@%K^X
`#!'!D
AcDbPolyline
10
28.61 : (Xf) X coordinate of the endpoint
of the arc
20
43.72 : (Yf), Y coordinate of the endpoint
of the arc
42
0.22 : Tangent of a quarter of the angle swept
by the arc
Xf, Yf: X, Y coordinates of the end point of
the arc.
R: Radius of the arc.
2. 3 Use of Mill AutoCNC Mill software and its
connection with the software Benchman for mechanizing
Runs the AutoCNC Mill Software. See
Figure 2.
Figure 2. Drawing part and generating CNC codes in
AutoCNC Mill software
2. 2 Conversion of coordinates to Numerical Control (NC) codes
Using the Basic Language for Visual Basic
6.0 was developed software named AutoCNC
Mill. The programming is described below.
The coordinates of the lines, the centers, radius, angles of the arcs and circles was read from
5#!%>H %?@!%<7)+I%5#!%U[YL%[Y\]O%"9CC$+&%
K^!7!@C$+D%\!$7@!:%V%\'<+"#+)$_D%-TTTX,%
ArchivoDXF Open For Input As # 1
>9%`#)@!%Y95%LW %K-X%a%O'<!
Line Input # 1, variable
Source: image from AutoCnc Mill © Software.
Loop
Close # 1
The main cutting parameters are introduced
as variables in text boxes of the application.
These parameters are: Total depth of the work
piece, feed rate of the tool in the XY plane and
depth in the plane Z, Speed of rotation of the
84
Complete the following dialog box to introduce the cutting parameters.
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Creation of Computer Aided Manufacturing software from
Computer Aided Design software in the milling process
Juan Carlos Carrasco García
Figure 3. Table to introduce cutting parameters
The CNC code is displayed in the next window:
Figure 6.%=Y=%`)+&9A
Source: image from AutoCnc Mill © Software.
Source: image from AutoCnc Mill © Software.
Save the CNC code.
In the Figure 3, the parameters have the next
units:
Avance en XY(Feed rate in XY Plane), Avan"!%!+%Q%K !!&%'$5!%)+%Q%$M)7X,%eCC%/%C)+f6
Distancia de seguridad (Distance of approach), Profundidad total (Total depth), Profundidad de pasada (Depth of cut), Diámetro de
fresa (Mill diameter): mm. Rev/min (Revolutions
per minute): rev/min.
Then run the software Benchman, by the
W\LY%F<559+D%9(!+%5#!%('!8)9<7%?@!%A)5#%!M5!+7)9+6%Y=D%"9+?I<'!%5#!%+!"!77$':%($'$C!5!'7%$+&%
through the VERIFY button simulate the milling.
See Figure 7.
Figure 7. Simulation of milling in Benchman Software
Click on the Abrir DXF button, to open the
;<59=;>% ?@!6% S!@!"5% d!+!'$'% =Y=% F<559+% 59%
generate the CNC code. See Figure 4.
Figure 4. Buttons Abrir DXF, Generar CNC, Imprimir
Source: image from AutoCnc Mill © Software.
The drawing area displays the sketch.
Figure 5. Drawing area
Source: by the author (simulation in Benchman 4000 © Software).
After the simulation, mount the piece in a
CNC mill for machining.
2. 4 Milling the parts
The piece with dimensiones 70 x 60 x 30 mm.
is mounted in the Machining Center Benchman
VMC 4000 located in the Robotics Laboratory
at Universidad Autónoma del Caribe.
The original set point is established in the
piece to proceed to mill with an end mill 6 mm.
in diameter. See Figure 8.
Source: image from AutoCnc Mill © Software.
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85
Creation of Computer Aided Manufacturing software from
Computer Aided Design software in the milling process
Juan Carlos Carrasco García
3. Results
4. Discussion
In AutoCAD was created the methodology
of route generation of displacement of the mill.
It is very important to work with Autocad
because it allows to obtain the coordinates and
characteristics of entities drawn from DXF format, as this is the information needed to develop
applications that process the data and generate
results from-CAD-Software.
It was developed the AutoCnc Mill software
to convert the CAD software AutoCAD into a
CAM software, allowing generate the CNC codes from the bidimensional drawing of the piece.
As can be seen in Figure 7, the simulation
did not generates errors displacement of the tool,
which motivated us the mechanizing of the piece.
It can be seen the real machining and the
resultant piece in the Figure 8 and 9.
Figure 8. Milling the piece in the Mechanizing Center
The machining was successful with the quality and the expected parameters.
Software AutoCNC Mill, the product of this
research shows that in Colombia is possible to
"'!$5!% 79J5A$'!% )+% 5#!% ?!@&% 9J% "9C(<5!'g$)&!&%
manufacturing.
Using this methodology it is possible to create other applications in the areas of Architecture,
Civil Engineering, Robotics, Mechanical Design,
Turning Process among others.
AutoCNC Mill can be enhanced in the following aspects:
Source: by the author (image: Robotic Labs at Universidad Autónoma
del Caribe).
Figure 9. The milled wokpiece
4%
Make it independent of AutoCAD.
Drawing the part within the samesoftware.
4%
Generate 3D simulation software within
the AutoCnc Mill or AutoCAD.
4%
Generate the toolpath of three-dimensional surfaces.
4%
Generate Calculating Application for
machining times and costs.
4%
Extending the program to accept other
CAD format, such as the parasolid kernel
<7!&%F:%S9@)&%`9'_%$+&%S9@)&%L&I!6
References
Carrasco, J. C. (2001). Curso Práctico Interactivo de Mastercam. CD-ROM. Barranquilla,
Colombia.
Carrasco, J. C. (2005). Curso Multimedia de
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Colombia: Edición de Polilinea.
Carrasco, J. C. (2006). Tecnología Avanzada
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Visión Para la Ingeniería, 6, 75-81.
Source: by the author (image. Robotic Labs at Universidad Autónoma
del Caribe).
86
CNC Software, Inc. (1998). Mastercam –Mill
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!"#$%&'(")"!*"+,-./0*"1$2"34"5" 0('$"6"7&'/!"8("9:4;
Juan Carlos Carrasco García
Creation of Computer Aided Manufacturing software from
Computer Aided Design software in the milling process
h<5iD%j6D%S"#$'_<7D%L6%V%U9F!'5D%^6%K-T.1X6%
Tablas para la Industria Metalúrgica. (3 ed).
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U)+%;6%V%U)<D%j6%K-TT.X6%;<59C$5)"%I!+!'$tion of NC cutter path from massive data points.
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Manual del Usuario. 5-10. Retrieved from http://
www.docentes.unal.edu.co/lhochoag/docs/SoftwareDesarrollado/01 CAD-IGMAS.pdf.
Pacheco, J. (2001). Cómo usar Mastercam.
Barranquilla-Colombia. Capítulos 1, 4.
^!7!@C$+D%E6D%\!$7@!:D%^6%V%\'<+"#+)$_D%`6%
(1999). Descubre Visual Basic 6. Madrid, España.
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Sarma, S. (1999). The crossing function an its
application to zigzag toolpaths. Computer- Aided
Des., 14, (31), 881-890.
O9I9'!7D% ^6% V% W5!'9D% =6% K2003X6% Programación en AutoCAD con Visual Lisp. Madrid,
España. Chapters 17-18.
!"#$%&'(")"!*"+,-./0*"1$2"34"5" 0('$"6"7&'/!"8("9:4;
87