Model of Mechatronics Robots Tool with Controlled Geometry Tadeusz Mikolajczyk1,a, Lukasz Romanowski1,b, Sebastian Sojka1 1
University of Technology and Life Sciences, Bydgoszcz, Poland a
[email protected],
[email protected]
Keywords: robot machining, mechatronics tool, polystyrene foam, hot wire cutting
Abstract. The paper presents a model of tool with controlled geometry of the active surface. This tool is very suitable for use with an industrial robot, for example, to form polystyrene foam. The tool was built in the form of two discs mounted on axes stepper motors positioned in the frame. This discs combined using two wires with feature a compensation its length. It was made using the spiral spring. Tool geometry was set by rotating one of the discs at a specific angle (0-180o). After starting the both engines, concurrently at the same direction, active surface of tool is obtained in the form of hyperboloid. To run the tool uses stepper motors connected to a computer equipped with an interface card and specially developed control software. Tool joined to the IRb60 robot wrist can obtain curved surface as a superposition of the kinematics of tool and robot wrist. Introduction The modern industrial robots were used in different jobs [1-15]. Robots are implemented not only to typical applications: automation welding jobs [4], assembling [4] and painting. Recently, the rapidly expanding use of robots for machining tasks can be observed. Many robots equipped with special tools for surface machining are used in cutting [1,3,4,7,11] and grinding [2,4,6,8-10] processes. These solutions are cheaper than conventional numeric control machine tool systems. Most surface processing with robots are programmed with CAM systems [4]. It is possible to use adaptive control of machining the unknown shape surfaces by using a special reverse engineering system [4,5] and system for surface recognition [6,8-10]. The new idea is the use of the robot equipped with tool for turning [4,7]. New approaches are using an industrial robot for rapid prototyping large sand moulds [4,12-14]. Rapid prototyping of models using robot was made from metal [12] and non metallic [4,13,14] materials. In rapid prototyping industrial robots are used for shaping, especially large model. in polystyrene foam [15-18] using hot wire. In this paper the technique of using robots for shaping polystyrene foam models have been discussed. Was presented a model of special mechatronics tool for industrial robot elaborated in the Department of Production Engineering, University of Technology and Life Sciences (Bydgoszcz Poland). This tool can change its active surface and in future will be used to shaping of polystyrene foam. Using of robot to polystyrene foam shaping Work is continuing towards the use of robots to form models of polystyrene foam by thermal cutting with hot wire. Tools are used by means of a straight wire (Fig. 1) [15,18] as well as special edges (Fig. 2) [16]. Presented is also the solution with controlled geometry of a flexible edge (Fig. 3) [17]. To ensure high accuracy in cutting with hot wire trajectory parameters must take account the formation slot, the width of which depends on the value of the current and feed rate (Fig. 4) [15]. For the purpose of modeling the wire rectilinear solid material developed a special methodology to generate models of a specific error e % reduced triangles using straight hot wire as a tool (Fig. 1) [18]. To increase the kinematics possibility was used 6 axis robot associated with a controlled two angle table [18] (Fig. 1). This system supports to create objects with complex surfaces. Examples of models shown in Figure 5.
Fig. 1 Tool with a straight wire for free cutting polystyrene foam - 6-axis robot works with two axial table - Michelangelo kinematics [18]
Fig. 2 Tool for thermal constrained cutting of polystyrene foam joined to the robots wrist [16] 1,60 1,40
crack k, mm
1,20 1,00 0,80 0,60 0,40 0,20 0,00 1,5
2
2,5
3
3,5
4
amperage, A
Fig. 3. Analogue geometrically flexible tool for polystyrene foam shaping [17]
60 mm/min
125 mm/min
200 mm/min
630 mm/min
1250 mm/min
1600 mm/min
Fig. 4. The influence of the electrical current and the feed on the slot in polystyrene foam forming [15]
Fig. 5. Model of head [18]: a) simplified model (s = 0.5%, 138 triangles), b) comparison of the original model (1390 triangles) and a) Idea of shaping curvilinear surfaces using line tool There is the possibility to the curvilinear surface form with a straight edge tool [19]. This is done by using oblique edge rotation which creates the rotational hyperbole as the active surface of the tool (Fig. 6). Different shape of hyperboloid depends on the inclination angle of oblique straight and its radius. In figure 7 was presented the sketch of the developed tools idea. Was used wire connected to the bases of a cylinder of diameter 2R and height L.
Fig. 6. Rotational hyperboloid created by rotation a oblique straight [19,20]
Fig. 7. Sketch for developed tool analysis
Right base of a cylinder with radius R and height L has been rotated by an angle comparison the left of the base, thereby causing a change in the position of the wire from |BB'| to |CB'|. From triangle AIC using trigonometric relationships determines the length of the triangle side |AI| = Ri AI cos (1) 2 AC therefore, by transformation distance of oblique straight from the axis x is: Ri
R cos
2 It is also the radius of the apex of the hyperbola. The angle of inclination of the oblique straight angle by rotation right base at 2 CI tan L
Since CI
R sin
2 R sin a tan
hence, the
2
(2) angle: (3)
angle can be determined from the formula:
2
(4) L At the constant distance of basis the wire length depending on the inclination angle: (5)) Li=Lcos By rotation the oblique straight obtained hyperboloid of revolution which is described by the formula: y 2 x2 z2 1 (6) a 2 b2 c 2 For z = 0 we obtain the equation of the hyperbole suitable for analysis and presentation of curvature of the arc: y 2 x2 1 (7) a 2 b2 The real axle of hyperbole is: (8) a Ri Imaginary axle of hyperbole: Ri b (9) tan After substituting a and b hyperbole parameter equation takes the form:
y2 Ri 2
x 2 tan 2 Ri 2
1
(10)
Because of y
angle value depends on
R cos
2
x
1 2
angle value after the substitution we obtain:
2
(11)
4 L tan
2
60
60,00
50
50,00
40
40,00 [o]
Ri [mm]
2 Equation (11) illustrates the nature of the tool - by changing the angle of rotation of the discs mutual gain changing the shape of a hyperboloid, which represents an axial section of a tool in the form of a hyperbola. The curvature of the resulting hyperbole can be calculated as the radius of the circle close to the hyperbolic tangent [20]: b2 Rh (12) a By substituting the hyperbole parameters: a (8), b (9) and simplification is obtained: Ri Rh (13) tan 2 After substituting the model data to (13) obtained formula: L2 Rh (14) 4 R tan sin 2 2 This relationship is useful for setting the tool in order to achieve a given curvature of the hyperbola apex rubber. Obtained relations were presented graphically (Fig. 8-12). Figure 8 shows influence of an angle value on Ri =a value. For using this tool to profiling of surface especially important value the radius of the circle close tangent to the hyperbola (Fig. 10) and influence of angle on hyperbole profiles (Fig. 12).
30 20
30,00 20,00
L=80
10,00
L=100
10 0
0
20 40 60 80 100 120 140 160 180 o
Fig. 8. Influence of angle value on Ri =a value (R=50 mm)o
Fig. 9. Influence of angle value on angle value (R =50 mm) at another value of L 150
1000
L=50
140
L=100
800 Rh [mm]
L=120
0,00
20 40 60 80 100 120 140 160 180 [o]
L=150
600 400 200
Li [mm]
0
130 120 110
0
100
0
40
80 [o]
120
160
Fig. 10. Influence of angle value on the Rh radius of circle close tangent to hyperbole
0
20
40
60
80 100 120 140 160 180
Fig. 11. Influence of angle value on Li length of wire for L=100 mm and R=50 mm
60 0 20
y, [mm]
50
40
40
60 80
30
100 120
20
140
10
160 180
0 -50 -40 -30 -20 -10
0
10
20
30
40
50
x [mm] Fig. 12. Hyperbole profile for different values of
angle
Design of hyperboloid tool Concepts of the tool shown in figure 13. This is a mechatronics tool with geometric and kinematics flexibility [21]. The tool was built in the form of two discs mounted on axis stepper motors FA-344-2 (4 phases, current: 4.6 A, jump rating: 1.8 °, torque: 1.8 NM ), company MIKROMA (Poland) placed in the frame (Fig. 13). Discs are combined with wire. Was used a compensation system of wire length using the spiral spring. Set the geometry of the hyperboloid surface was made by rotating one of the discs at a specific angle (0-180o) obtained by the inclusion of one of the engines. Hyperboloid surface is obtained when the position of the wire is oblique (Fig. 7). After concurrent starting the of both engines active surface of tool is obtained in the form of hyperboloid. The developed tool can change their active surface from the cylindrical surface to the hyperbole any profile (Fig. 12). The tool is controlled using a PC via a card stepping motors (SMI) OBR's USN (polish), together with a specially made power supply. At figure 14 was presented view of made tool. Presented design of mechatronics tool is under development. This model was made for verification of the control concept tool. Was used control its active surface by rotating the oblique position of the wire and then rotation with two engines. The work will be built to allow the power supply wire work on thermoformed polystyrene foam. frame
stepper motor
stepper motor
disc wire
disc
monitor
fedder
SMI
PC
Fig. 13. Hyperboloid tool and its computer control system
frame stepper motor stepper motor disc disc wire
Fig. 14. View of IRb60 robot wrist equipped with presenting tool Tools simulation Tools simulation system shown in Figure 15. It is made using the special software HiperTool written in VB 6. The program introduces the data of the angle of rotation of the disc, and data movement tools working. The developed software allows you to preset the tool by rotation one of the discs to a specific angle to obtain the desired oblique position of the wire. Was shown the angle value (first panel Fig. 15) for tools L and R parameter (second panel). The third panel of this form lets you specify the speed of the tool and simulation time. The developed software enables the visualization of running the tools (Fig.15). Visualisation of the surface of the tool, made in CAD software, as shown for example in Figure 16. This surface can be changed during the rotation of the tool. Presented simulation software will be used in the next jobs to make special system to control stepper motor of presenting mechatronics tool adequate as [18] and with control of industrial robot IRb60 [4,19]. Traffic shaping is performed by moving the robot tool using IRb60. To control the robot using a special form of program that allows both manual and using control file.
Fig. 15. Main form of HiperTool software
Fig. 16. Visualisation of the active surface of hyperboloid tools active surface
Conclusions The developed tool is a mechatronics flexible geometry kinematics solution [11,21]. It uses the original design involving the simultaneous use stepper motors to control the shape of the tool active surface and to driving the working traffic. The concept of the tool can be found universally used in the machining of the surface shapes. Presented theoretical analysis of proposed tool is the basis for tools shape control. Diameter of apex of hyperbole change in value of angle rotation accordance with relation (2). It is possible to use all parts of cutting wire for machining curvilinear surface with hyperbole profile using formula (11) or use only the central part for formation circle using formula (14). The design of the tool must provide the ability of surface shaping. Presented design makes possible change the shape of tools active surface in time of machining process. In the further work, need use of the tool to practice. For example, the formation a polystyrene foam model with hot wire using - this requires equipment of tool in system for current supply wires for the implementation of thermal cutting. Need practical experiments to research of shaping process of polystyrene foam with this tool using an industrial robot. References [1] Y. H. Chen, Y. N. Hu, Implementation of a Robot System for Sculptured Surface Cutting. Part I Rough machining. Int. J. Adv. Manuf. Techn., vol. 15, (1999), pp. 624-629 [2] Y. N. Hu, Y. H. Chen, Implementation of a Robot System for Sculptured Surface Cutting. Part II. Finish machining. Int. J. Adv. Manuf. Techn., vol. 15, (1999), pp. 630-639 [3] H. Latos, T. Mikolajczyk, Surface Shaping with Industrial Robot. OPTIROB’2006, Predeal, Romania, University "POLITEHNICA" of Bucharest, (2006), pp. 265-269 [4] T. Mikolajczyk, Manufacturing Using Robot. Advanced Materials Research, vol. 463-464, (2012) pp. 1643-1646 [5] T. Mikolajczyk, Robot Application to Surface Finishing, Journal of Polish CIMAC, Vol. 5, Nr 3, (2010), pp. 107-112 [6] T. Mikolajczyk, Indication of Machining Area with the Robot's Camera Using, Applied Mechanics and Materials, vol. 282 , (2013), pp. 146-151 [7] T. Mikolajczyk, Robot-Turner. Advanced Materials Research, vol. 463-464, (2012), pp. 16821685 [8] T. Mikolajczyk, System to Surface Control in Robot Machining. Advanced Materials Research, vol. 463-464 (2012), pp. 708-711 [9] T. Mikolajczyk, Videooptical Surface Shape and Integrity Estimation in Robots Machining, Applied Mechanics and Materials, vol. 332, (2013), pp. 431-436 [10] T. Mikolajczyk, P. Wasiak, Machining with Image Recognition Using Industrial Robot. Applied Mechanics and Materials, vol. 186, (2012), pp. 50-57 [11] H. Latos, T. Mikolajczyk, Virtual Aid to Design of Geometric and Kinematics Flexible Tools. XII Workshop on Superv. and Diagn. of Mach. Sys.. Virtual Manuf., Karpacz, Poland, (2001), pp. 145-152 [12] F. Ribeiro, J. Norrish, Case Study of Rapid Prototyping using Robot Welding. http://repositorium.sdum.uminho.pt/bitstream/1822/3083/1/12%20PROBOT~2.pdf [13] T. Mikolajczyk, J. Lewandowski, Kszta towanie przyrostowe z zastosowaniem robota przemys owego. (Rapid Prototyping Using Industrial Robot.) In ynieria i Aparatura Chemiczna, nr 3, (2011), pp. 51-57, (in polish)
[14] Giant Robot Prints Chairs from Ground-Up Refrigerators [Video] http://www.fastcodesign.com/1662793/giant-robot-prints-chairs-from-ground-up-refrigeratorsvideo?partner=co_newsletter [15] T. Miko ajczyk, P. Milko, Shaping of Polystyrene Foam Products with Industrial Robots. OPTIROB, Predeal, University “POLITECHNICA” of Bucharest, (2006), pp. 261-264 [16] A. Pusthuma, Development of a Novel Robotically Effected Plastic Foam Sculpting System for Rapid Prototyping and Manufacturing http://ir.canterbury.ac.nz/handle/10092/1209 [17] I. Horváth, S. Joris, M. Vergeest, I. Juhász, Finding the Shape of a Flexible Blade for FreeForm Layered Manufacturing of Plastic Foam Objects http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.27.4242&rep=rep1&type=pdf19 [18] J. Zhu, R. Tanaka, T. Tanaka, Y. Saito, An 8-Axis Robot Based Rough Cutting System for Surface Sculpturing, The 11th International Conference on Precision Engineering (ICPE), Tokyo, Japan, No.16-18, (2006-8), pp 139-144 [19] H. Latos: Zastosowanie ostrzy o prostoliniowych krawedziach do obrobki powierzchni, (Implementation of Straight Cutting Edges for Surface Machining). Zeszyty naukowe Akademii Techniczno-Rolniczej nr 51, Mechanika 19, Bydgoszcz 1978, (in polish) [20] J. Bronsztein, K. Semendaiev K., Matematyka. Poradnik Encyklopedyczny. (Mathematics. Encyclopedic Handbook), PWN Warszawa, wyd. XX, 2004 (in polish) [21] H. Latos: Elastycznosc geometryczno-kinematyczna narzedzi skrawajacych, (Geometrics and Kinematics Flexibility of Cutting Tools) . Wydawnictwo Uczelniane Akademii TechnicznoRolniczej, Bydgoszcz, 1997 (in polish) [22] T. Mikolajczyk, L. Kamieniecki, PC Controlled Turning Tool. Applied Mechanics and Materials, vol. 325-326, (2013), pp.1110-1114 [23] T. Mikolajczyk, Modernisation of IRb60 Industrial Robot Steering System. OPTIROB'2007, Predeal, Romania, University "POLITEHNICA" of Bucharest, (2007), pp.149-152
