USING ADAMS FOR MECHANISM SIMULATION APPLICATION OF MULTIAXIS MACHINES

Transcription

1 USING ADAMS FOR MECHANISM SIMULATION APPLICATION OF MULTIAXIS MACHINES Yi-Ming Lee 1, Kuei-Shu Hsu 2 and Shyue-Bin Chang 1 1 Department of Mechanical and Automation Engineering, Kao Yuan University, Taiwan 2 Department of Applied Geoinformatics, Chia Nan University of Pharmacy & Science, Taiwan t30003@cc.kyu.edu.tw, kshsu888@mail.chna.edu.tw, t30029@cc.kyu.edu.tw ICETI 2012-V1007_SCI No. 13-CSME-88, E.I.C. Accession 3546 ABSTRACT The aim of this paper is to implement the efficiency of the new model multi-axis CNC machine by using a visual solid mechanism simulation methodology design. The advantage of this simulation design is to activate each running procedure simultaneously when a transient motion occurs in the mechanism system. Using the simplified elements of a conceptual dynamic mechanism simulated by ADAMS we will demonstrate the feasibility in design through kinematics analysis of the new five axis CNC model. Keywords: multiaxis; ADAMS; CNC. L APPLICATION DU SYSTÈME ADAMS POUR LA SIMULATION MÉCANIQUE DE MACHINES MULTIAXIALES RÉSUMÉ L objectif principal de cet article est de mettre en IJuvre l efficacité du nouveau modèle de machines multiaxiales CNC en utilisant un mécanisme de simulation méthodologique visuel et solide. L avantage de cette conception de simulation est d activer chaque processus simultanément quand un mouvement transitoire survient dans le système mécanique. En utilisant les méthodes simplifiées d un mécanisme conceptuel dynamique simulé par ADAMS, nous démontrons la faisabilité du concept par des analyses cinématiques du nouveau modèle à cinq axes CNC. Mots-clés : multiaxial ; ADAMS ; CNC. Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3,

2 1. INTRODUCTION During the past decade, the government introduced its policy to promote the development of advanced machine tool in design and quality. Currently in industrial application, the promotion relates to development of more advanced machine tool product in all respects, which should be compatible to the product from countries such as Germany and Japan in the global market. The basic A+ 0.1 mm precision class technology must be utilized with not only the extreme precision of machine itself, but also a high level of the reliability and quality of critical parts, in order to differentiate our products from the competing products produced by Korea and China. The accuracy of machining work during high speed cutting in production can be affected by various factors mainly from machine tool itself, machining method, and environmental condition. The machine tool factors include construction geometry errors, dynamic errors etc. The operation method factors include thermal strains, structure stress/strains, and so on. To fight against the thermal strains, some compensation ways had been developed under the joint efforts from industry and academic group, but in fact this solution is considered as a patch solution only rather than a solution to the root of the problem, there still needs certain specified ways to achieve. As for the environmental factors, they include environmental temperature, external vibration, etc. For the mechanism simulation of machines or devices, most methods use the homogeneous transformation matrix method or kinematic analysis method to derive the coordinate system. Liu simulated the dynamic behavior of multi-missile launcher vehicle by applying ADAMS software with which 3D launcher system was developed in graphic software, in which the relation of the bodies was defined through ADAMS/VIEW, and followed by analyzing the mechanism and control system [1]. Wang [2] demonstrated the simulation of high speed mechanism of the cutting tool system with cutter moving track by applying ADAMS visual graphic animation so as that the dynamic interference can be predicted through analysis. Chang [3] demonstrated the simulation of the model of multi connection truck of complex mechanism followed by computer analysis of motion status in which the combination of parameters was selected as input to the simulation software at different steering angles and speeds. Hung [4] established the kinematics analysis, defined the coordination system, derived the motion equation and observed the motion mode of machine tool simulated by 3D visual realty in order to detect the interference and collision in the motion. Din [5] constructed the track vehicle for the restricted condition of the movement by using ADAMS simulated dynamic software in order to improve the elements of the track system under the subjected forces. It is well recognized that observation on motion simulation can describe more complex sources and present a reliable model. The focus of this paper will be on the expression of the visual and practical effects of machine tool operation during the initial design process by applying the animated simulation method under defined machining operation condition [6, 7]. This study offers the possibility of doing error analysis by simulating against the effect of strains/stresses as cutting force is applied at different angles to the work piece. The result of the analysis will, in term, be capable of evolving the coefficient or comparison chart against errors as changes in force and/or direction and/or angle occurred. As a result, optimized design can be determined effectively. For example, the material can be selected to the use of composite material in the future providing not only weight reduction but also in devoting to the contribution to A+ machine tool base technology development. 2. MODEL CONSTRUCTION The example of study of multiaxis machine tool is illustrated and shown in Fig. 1. The multiaxis machine tool supports translation in three linear directions (X, Y, and Z axes), and also two rotations on the spindle and the work piece table respectively. Based on spindle head moving direction vertically or horizontally, the machine is classified as serial type and horizontal type. Each axle movement is driven by an individual servo motor with an independent control system Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3, 2013

3 Fig. 1. Schematic of multiaxis machine architecture. The serial type machine is superior in its versatility in combination of grouping the axes to adapt to various types of design articles to be machined. The objective of this study is to create the visualized and simulated movements on the visual five axis machine, and then verify the motion mode and kinematics derivatives followed by evolving the correlation of force with strains/stresses while changing the spindle force at different angles applied, based on the defined elasticity rotary spindle head. The appearance of the machine is defined as considerable freedom with three linear axes and two rotary angles in A and C respectively. In the transformation of movement in the mechanism with its application, in general, the incremental amount of movement and rotation expressed in the form of matrix can be described with great satisfaction. The cutting tool platform extends to the A axis while the latter is positioned to the Z axis linear platform and, finally, the cutting tool axis is positioned at a rotated platform on the A axis. According to the above arrangement, each parameter of the movement of the platform can be described as defined as bx, by, bz, qx, qy and qz. The transformation of coordination is presented in Fig. 2. Generally speaking, for kinematics analysis, the solution of kinematics for the serial type assembly mechanism is much easier than that of the parallel type. In order to obtain the object location and angle through the output of each driving shift, the kinematics analysis must be conducted in advance. In the movement of mechanism in kinematics, the track or amount of movement along with rotation must be expressed in matrix form. The following equations show how to define the original starting point all the way through the cutting tool by the coordination of cutting tool in matrix form (as can be seen from Eqs. 1 5): [ ref T tool ] = ref T x table x table T z table z table T a axis a axis T tool cosθ sinθ 0 b x = sinθ cosθ 0 b z O zay O at (1) In addition, by transforming from coordination of work piece to matrix form, the equation can then obtain the relation between the five axis machine cutting tool coordination system to the work piece coordination Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3,

4 Fig. 2. The coordination transformation in multiaxis system. system where P x P y P z 1 wp = [ ref T d ] 1 [ ref T tool ] P x P y P z 1 tool = [ ref T tool ] 4 4 [ [ ref [ T tool ] = ref R tool ] 3 3 [ ref A tool ] [ ref R tool ] 3 3 = cosθ cosα sinθ cosθ sinα sinθ cosα cosθ sinθ sinα sinα 0 cosα [ ref A tool ] 3 1 = cosθ(b x ) + sinθ(b z + O yb ) sinθ(b x ) + cosθ(b z + O yb ) Ozay Oat + b y + d ] q x q y q z 1 tool (2) (3) (4) (5) 1016 Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3, 2013

5 Fig. 3. The CAD design of assembly drawing. Fig. 4. The explosion drawing of the main structure. Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3,

6 Fig. 5. The solid model transfered into ADAMS from SolidWorks. 3. SYSTEM DESIGN The graph software SolidWorks is utilized to virtually establish a major part of each platform for its appearance and dimension, and conduct assembly according to inter relation positioning and visual requirement in the software, then pre-set up the basic motion limit. Next, upgrade the CAD to CAE from 3D data model in the SolidWorks file to higher level dynamic simulation software ADAMS. Before conducting the simulation test, the more complicated and precise motion limitation and simulation data shall be re-set up again. The tradition machine tool design is based on specific design data to pre-produce numbers of prototype of physical machine tool. The exact number is based on the needs of test objectives mainly for accumulating a huge amount set of comparative data, at relatively similar test condition, which is adequate enough for the analysis in order to feed back for design change and modification. This repetitive trial and error experimental approach is very much time consuming and costly in material or labor. In the process of developing a visual machine tool, high lever graphic software SolidWorks is used to create a simulated model with dimensions defined for each part, followed by assembling the parts and setting the relation of the motion of the parts. The proposed visual five axis machine features three linear translations through the travel gear driven by each independent servo motor and guided by linear slide rail along the axis. The platform (table) can not only move linearly along the axis but also rotate around the axis. The structure is presented in Fig. 3. This step will explain how to build up the machine tool model within design drawing software Solid- Works, and then derive the analysis software ADAMS for detail analysis. To create a visual solid model within SolidWorks software for each major component and/or part necessary for each of axis orientation with defined specification and dimensions for each part. After constructing the solid model for each part, the assembly can then be conducted by simulated positioning in accordance with SolidWorks assembly software. The explosion drawing of the simulated assembly is shown in Fig. 4. To transfer the original data file format *.sldasm to *.igs *.x_t by using file rendering function, load into the high lever analysis software ADAMS as shown in Fig. 5. The solid model is categorized into four types 1018 Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3, 2013

7 Fig. 6. The verification and simulation of drill operation performed in ADAMS. named as Rigid Bodies, Flexible Bodies, Point Masses and Ground Part. The rotation of axel of the work piece coordination is defined by Euler in which either the Body-fix or Space-fix method can be selected. After transforming the solid data model to dynamic analysis software ADAMS, the movement limitation module built inside the software shall be applied to allow the moving parts being properly limited to some degrees. In ADAMS, set the mechanism coordination system first, and then adjust the model accordingly between different software interfaces to avoid data loss and keep the unit consistent. The visual five axis machine s moveable platform has five degrees of freedom moving in X, Y, Z axes linear translation plus the rotation of the table (to which the work piece is attached) and the spindle (to which cutting tool is attached). Planning a moving path of platform (table) by a simulated drilling operation at 90, 45, and 0 degrees respectively is necessary, in which the 90 degrees and the 0 degree drill are single axis movement actions while the tilted 45 degrees drill is of two axis movement combined action. To verify that the behavior of the movement of the visual machine is more realistic, the computer numeric calculation is performed in the ADAMS software, and also the Step Function supported by ADAMS is applied to create the motion parameter necessary for conducting the simulation and analysis. During the simulation process, the sensors are used in connection with limitation setting to limit the travel of the movement. The simulated automatic Step Function features the sense of realistic as in the real machine operation. By substituting the parameter of motion of drive unit into the Step Function as STEP (time, 1, 0, 1*5, 30d), in which time is unit defining the amount of movement of 30 degrees within five second,and with the same method to define the motion of the unit on other axis, the combined movements make simulation possible. The verification and simulation of the 0 degrees drill operation is conducted by input parameters to the Step Function as shown in Fig. 6. By applying the finite element elastic method, PATRAN is used in structure design to model the construction of five axis machine. Then construct an elastic body by applying elastic structure analysis software PATRAN in more detail in a manner where the variances of strains/stresses can be detected when force applies to the spindle. To begin with, the selected body shall be netted as shown in Fig. 7. Finally, we verify the modules simulated numbers and the frequencies on the elastic head. Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3,

8 Fig. 7. The spindle head meshed by PATRAN. Fig. 8. Dynamic simulation for the cutting tool. 4. RESULT AND DISCUSSION To simulate the motion behaviors in the visual five axes machine, a drill operation of 90, 45, and 0 degrees is selected for demonstration. By writing in the function provided by ADAMS, it will generate the track charts from the simulated motion. By lapping the two motion data in one chart, one obtains the track of motion of cutting tool on the Y Z plane. The track of dynamic simulation for the cutting tool is shown as a photo image in Fig Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3, 2013

9 Fig. 9. Variances of (a) stress simulation and (b) strain simulation on the rotary spindle head. To simulate the change in strains/stresses to the cutter at different rotation angles and different amounts of movement under the same force applied, there are variances in strains/stresses at the 90 degrees angle to the vertical axis as indicated in Fig. 9 for the color contrast on block against the stress area subjected to forces on the rotary head. The strain/stress relation can be observed by a change of colors in different blocks. The amount of strain can be determined clearly by measuring the cutter position as errors occur. By measuring the tip of the cutter as recorded, the change in precision under the force applied can be determined. 5. CONCLUSIONS The prime objective of this paper is to analysis the simulation of the movement of multiaxis machine by applying simulation technology on a visual machine in a manner that is capable of conducting preliminary design functional test effectively. In this approach, the existing parameters of material property can be input in order to make the visual machine as real as possible. This new design process approach will make machine tool development much more effective both in time and cost. Simulation by utilizing finite element analysis elastic method other than solid application to the spindle head will be closer to the status of real machine operation, which indeed can reveal the variation of strain as the stress is applied to the spindle head. Through the measurement, the relations between cutting forces and variances of error can be obtained, on which the change in material and design is based. REFERENCES 1. Lue, P.-W., The dynamic analysis of multi-missile launcher system in the application of ADAMS simulation (2nd research), Chung-San Institute of Science and Technology, Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3,

10 2. Wang, S.-K., 3D motion simulation to the mechanism of 4 axis CNC machining center, Taiwan ADAMS User Seminar and Academic Thesis Delivery, Chang, C.-P., The simulation and analysis of joint truck in steering performance, The Military Combined Services-Logistic, Hung, J.-S., The kinematics and collision simulation and analysis of 6 axis CNC machining center, Master s Thesis, Mechanic Engineering, National Chung-Chang University, Ding, C.-J., 3D motion simulation and dynamic analysis of track vehicle, Master s Thesis, Department of Mechanical and Automation Engineering, Da-Yeh University, Fu, T.-N., Computer Aided Design ADAMS Basic Application Manual, Kao-Lie Book Company, Taipei, ROC, Shiah, S.-F., The rigidity analysis of visual dual axis linear guide platform, Master s Thesis, Department of Mechanical Engineering, National Yunlin University of Science and Technology, Transactions of the Canadian Society for Mechanical Engineering, Vol. 37, No. 3, 2013