Papers by Keyword: Static Stiffness

Abstract: The worktable and the mainframe of the flipping horizontal machining center can be separated. The performance of the mainframe largely determines the machining performance of the whole machine. The deformation of mainframe under the application of certain forces demonstrates its static characteristics, which helps to find the vulnerable points for improvements. This paper mainly discusses the modeling of ball screw interfaces by taking into account the interface modeling. Static analysis is made by using Workbench to provide guidance for structural improvements.This electronic document is a “live” template and already defines the components of your paper [title, text, heads, etc.] in its style sheet.

Abstract: There is a compelling need for development of a surface grinding machine for 450mm diameter silicon-wafers. The authors have developed a new surface grinding machine for the large scale silicon-wafers. The machine has a rotary work table equipped with a constant-flow hydrostatic water bearing. The table system has to attain high static stiffness to achieve higher loop stiffness. This paper investigates static performances of the rotary table by numerical computation. The obtained results are compared with the experimental ones. Accordingly, it is verified that the developed rotary table has sufficient static performances for the large scale silicon-wafer grinding machine.

Abstract: The finite element model of heavy-duty machine tool’s ram components has a large number of elements, many contact pairs for assembly and a large-scale optimization calculation, which make the optimization difficult to conduct. To solve this problem, a static stiffness optimization method of the large component based on the equivalent elastic modulus is put forward. The proposed method is applied to super-heavy-duty CNC floor-type milling and boring machine of TK6932 as a case study. Based on the principle of the equivalent stiffness, the ram assembly with complex constraints and contacts is equivalent to a ram part without other components, the calculation method of the equivalent elastic modulus is analyzed and the equivalent elastic modulus formula of the ram under the bending load is derived. Taking the four box-walls’ thickness and the three stiffened-plates’ thickness of the ram as the optimization variables, the minimal volume under static loading as the target and the maximal displacement and stress as the constraints, the optimized mathematical model of the ram’s equivalent static stiffness is established. The results of the optimization are rounded according to the sensitivity analysis. Besides, the optimization effect is proved by simulation through the finite element technology. The optimization procedure and results show that the simplified method based on equivalent elastic modulus presented in the paper can control the calculation scale effectively, and ensure the process of the optimization smooth.

Abstract: The worm geared transmission chain is widely employed in rotary feeding table of machine tools. This article proposes a static stiffness model and conducts sensitivity analysis of the transmission chain. Firstly, a unified static stiffness model is established, considering meshing stiffness, torsional stiffness and pre-load related axial stiffness of worm shaft. Then sensitivity with respect to individual stiffness element is derived based on partially differentiating method. Simulation results show that the closer to the end gear pair or shaft is, the more sensitive meshing stiffness or torsional stiffness is.

Abstract: Taking a grinding machine tool as an example, this paper obtained the static stiffness of the machine tool by finite element analysis method. The structure and technical parameters of the machine tool were introduced at first.Then, the finite element model of the machine tool was established. The static stiffness of the machine tool in x-, y-, and z-directions were simulated at last. The results show that, the static stiffness in x-direction is 2.0062×10⁷ N/m, the static stiffness in y-direction is 0.821×10⁷ N/m, and the static stiffness in z-direction is 0.2992×10⁷ N/m. This paper provides advices for structure optimization of the machine tool which is convenient for improving the machining accuracy.

Abstract: The fundamental theory about the constitutive relationship of hyperelastic model has been introduced and the model of super-elastic coating has been simulated in this paper. The static stiffness of different coating thickness has been calculated considering the hyperelasticy and viscoelasticity. Through the studying, because of the increasing of deformation, the compression static stiffness of the hyperelastic coating will be increased; while the tension static stiffness of the hyperelastic coating will be decreased. Moreover, the static stiffness is only related to the relative deformation not the absolute deformation.

Abstract: The implicit parametric method was briefly discussed in this paper. An implicit parametric 3D solid model and a finite element (FE) model of a body-in-white (BIW) were built up by this method. Low order natural vibration frequencies and modes, bending and torsional stiffness of the BIW were analyzed by FE calculation. A good agreement was acquired by comparing the prediction results with the test values. Results indicated that the implicit parametric model of the BIW established could be used for design and development of the BIW in concept design stage of the BIW.

Abstract: In this paper a model for the mechatronic position servo system with disturbance forces is presented. Static and dynamic stiffness for the proposed model is analyzed. An equation for analytical calculation of the static stiffness is developed. Correctness of the proposed equation is experimentally verified. Simulation of the influence of some parameters on the static and dynamic mechatronic position servo system stiffness is performed with simulation program MATLAB & SIMULINK.

Abstract: To reveal the static stiffness behavior of a 6-PTRT parallel robot and find out its change rule in order to provide the reasonable parameters for the structural design, the stiffness characteristics of this parallel mechanism was studied. Based on the influence coefficient method, a static stiffness model for 6-PTRT parallel robot was established. The proposed model considered not only the axis stiffness of actuator but also the stiffness of passive joints, and the change of Jacobian matrix and first-order influence coefficient brought about by tiny change of the parallel robot mechanism's configuration under external wrench. The static stiffness matrix of parallel robot in initial position and its stiffness distribution rules for a certain workspace were given by numerical calculation and finite element method, which comparatively verify the exactness of stiffness model.

Abstract: According to the spatial arbitrary cross-section beam simplification redundancy and coupled problem of model constraint mutually relation, for the variable cross-section beam of 5-axis gantry machine tools, a new beam simplification algorithm and the average second inertia concept is created by structural mechanics theory. Under gravity and cutting load of beam, It applied simplification algorithm and finite element analysis software (Nastran) to study the static and dynamic characteristic comparatively, deformation relative errors are less than 5%. The modal analysis of beams get the order natural frequency and vibration mode, contrast analysis with experimental value, the relative errors are less than 9% each other. Through theoretical analysis and experimental data shows that the simplification algorithm is practicability and accuracy, it play a role in the key components of machine tools analytical characteristics and machine tools of performance prediction.