Papers by Keyword: Multi-Body System

Abstract: Cause of machining error for NC Machine Tools is described, and principle of NC machinings error compensation on the basis of the existing in-line detection model of NC machine tools is analyzed in this paper. Regularity of error Modeling based on multi-body system is found,accordingly, we will find the corresponding characteristic matrix and transformation matrix if location features and sport features of the adjacent body are confirmed. Then, formula of error model is found, and we can get numerical solution and compensate error according to the identified error parameter. As a result, the machining accuracy of machine tools can be greatly improved.

Abstract: The machining accuracy of NC machine can be improved significantly through the error compensation. The kernels of (multi-body system)MBS theories are that the number arrays of low-order body are used to describe the topological structures which are taken to generalize and refine MBS, and the characteristic matrix are employed to represent the relative positions and gestures between any two bodies in MBS. Based on the theory of rigid body dynamics and homogeneous coordinate transformation techniques, the space error model of five-axis gantry NC machine can be established, the modified NC instructions can be obtained and it prepares well ready for the software error compensation and the practical application. Gyratory motion of five-axis NC machine will generate the coupling of translational motion, so it is different from the three-axis NC machine in the process of error compensation and we need to decoupling.

Abstract: In the past finite element analysis (FEA) and multi-body system simulation (MBS) were two isolated methods in the field of mechanical system simulation. Both of them had their specific fields of application. In recent years, it is urgent to combine these two methods as the flexible multi-body system grows up. This paper mainly focuses on modeling of the spindle system of hammer crusher, including geometric model, finite element model and multi-body dynamics (MBD) model. For multi-body dynamics modeling, the contact force between hammer and scrap steel was discussed, which is important to obtain the impact force. This paper also proposed how to combine FEA and MBS to analyze the dynamic performance of the spindle system by using different software products of MSC.Software.

Abstract: In this paper, we attempt to study the influence of the bushings (compliant joints) on the static behavior of the guiding system used for the rear axle of the vehicles. In fact, we are interested to determine the difference in behavior between the compliant model (with bushings) and the rigid model (bushings modeled as spherical joints) of the axle guiding mechanism. The static model, in which the car body is attached to ground, is a constrained, multi-body spatial mechanical system, in which the bodies are connected through geometric constraints, compliant joints, and force elements. The external loading is made by vertical forces applied to the wheels, in stationary regime. The study is made for the general groups of guiding mechanisms, with M=1 and M=2 degrees of mobility, by using the MBS (Multi-Body Systems) environment ADAMS of MSC Software.

Abstract: Based on multi-body system, the error model of gantry five-axis NC machine tools was discussed. The calculate method of precision process equation and NC instruction has been derived out. Based the above research works，make a emulate by using of geometry error compensation soft-ware. The result show machining precision can be improved through the error compensation method which is concluded in this paper.

Abstract: Analyzing some main errors of NC spiral bevel gear honing machine-tool, the elements of geometric error, thermal error and force error etc., which are constructed 39 error sources of the machine by stack method. Based on multi-body system theory, using homogeneous transfer matrix(HTM) method to present six feature matrixes that includes ideal-static matrix, ideal-kinematic matrix, ideal-static translation error matrix, ideal-static rotary error matrix, non-ideal rotary motion error matrix and non-ideal translation motion error matrix, which are built between of adjacent body. Finally, the synthetic volumetric error model of six-axis honing machine-tool is established.

Abstract: The paper presents a miniaturized two-spindle rapid denture repair system with applications on CAD/CAM dental restorations. The necessary functions possessed by denture processing system in medical treatment environment were defined, and the main technical parameters of the machining system were determined. The modal tests of the system structure were conducted for the key areas vibration mode. The volumetric geometric errors of the system were measured with laser interferometers. At last, the milling experiments of human molar crown denture were carried out with the mean surface roughness Ra value 0.8μm, which is consistent with the requirement of dental restoration.

Abstract: According to the multi-body system theory and geometric topology analysis method, combining the geometric structure and working principle of thread NC grinder, made the kinematics analysis for each parts of NC grinder. And the mathematical model for geometric topology structure of grinding machine system was established; the precision machining equations of NC grinder was deduced. Furthermore, the paper used the coordinate transformation principle of homogeneous to deduce the precision processing equation of NC grinder, all of that was based on the moving relationship of the machine tool, the workpiece and the grinding wheel, and got a kind of method that it can use multiple line grinding wheel to grind small radius, small screw pitch and multiple thread. This method laid a theoretical foundation for NC grinder machine processing which used multi-line grinding wheel to grind threads, and improve the grinding efficiency and precision of multi-line grinding wheel; in addition, this method has obtained good effect in grinding thread production.

Abstract: Kinematic accuracy is a key reason which influence workpiece's geometric error precision on traditional working process of precisely CNC（Computerized Numerical Control）P3G（polygon profile with 3 lobes） grinding machine. A systematic geometric error model has been presented for CNC P3G grinding machine， proposed multi-body system theory integrate with the structure of CNC P3G grinding machine tools, researched on the machine's space geometric errors. By means of separate geometric errors from the machine tools, build geometric mathematical error model. Then, identify 21 error parameters through method of 9 lines, analysis and calculate the total space geometric errors of the workpiece and wheel. Finally, formed a parameter-list and applied software error compensational technique ， achieved real-time control to the motions of workpiece and wheel. Experimental results shown that the geometrical error modeling technique is accurate and efficient, and the precision of CNC P3G grinding machine is highly raised 70%.

Abstract: With the first kind of Lagrange’s equations, this paper presents the dynamical equations of multibody system with friction constraints. The generalized forces of friction forces are described in the form of matrix. Considering numerical method is widespread to analyze the characteristics of multibody system dynamics, this paper compares the two friction laws for solving the multibody system problem with dry friction constraints. Using Baumgarte’s and augmentation method, the differential-algebraic equations are given in the form of differential equations matrix to raise calculating efficiency. The friction force for Coulomb’s friction law and the continuous friction law is denoted, which converts subsection smooth systems to continuous smooth systems. An example is given to evaluate the validity of continuous law of friction. The numerical simulation shows that continuous law of friction is an effective method to process multibody system friction problem. The work in this paper also provides a new direction to research the non-smooth multibody system dynamics equation.