Study on Dynamic Stiffness of Machine Tool with Consideration of Friction Damping in Guide

2012 ◽  
Vol 497 ◽  
pp. 68-72 ◽  
Author(s):  
Miki Shinagawa ◽  
Eiji Shamoto
Keyword(s):  
Machine Tool ◽  
Friction Force ◽  
Machine Tools ◽  
Design Method ◽  
Dynamic Stiffness ◽  
Testing Machine ◽  
Variable Stiffness ◽  
Major Influence ◽  
Chatter Stability ◽  
Friction Damping

The purpose of this study is to acquire design method of machine tools with higher dynamic stiffness and consequently higher chatter stability. This study focuses on stiffness of main structures and friction damping in guide of a machine tool, because stiffness and friction damping are considered to have major influence on the dynamic stiffness. A special testing machine with variable stiffness and friction was developed to clarify effects of the stiffness of main structures and the friction in guide on the dynamic stiffness and therefore the chatter stability. The stiffness of main structures and the friction in guide were changed experimentally, and it was clarified that the optimal friction force exists at every stiffness condition, and that higher stiffness does not always lead to higher stability.

scholarly journals Analysis of Dynamic Characteristics for Machine Tools Based on Dynamic Stiffness Sensitivity

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2260
Author(s):  
Chunhui Li ◽  
Zhiqiang Song ◽  
Xianghua Huang ◽  
Hui Zhao ◽  
Xuchu Jiang ◽  
...  
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Dynamic Stiffness ◽  
Variable Stiffness ◽  
Structural Vibration ◽  
Dynamic Experiment ◽  
Machine Tool Structure ◽  
Analysis Experiment ◽  
Five Axis

Dynamic parameters are the intermediate information of the entirety of machine dynamics. The differences between components have not been combined with the structural vibration in the cutting process, so it is difficult to directly represent the dynamic characteristics of the whole machine related to spatial position. This paper presents a method to identify sensitive parts according to the dynamic stiffness-sensitivity algorithm, which represents the dynamic characteristics of the whole machine tool. In this study, two experiments were carried out, the simulation verification experiment (dynamic experiment with variable stiffness) and modal analysis experiment (vibration test of five-axis gantry milling machine). The key modes of sensitive parts obtained by this method can represent the position-related dynamic characteristics of the whole machine. The characteristic obtained is that the inherent properties of machine-tool structure are independent of excitation. The method proposed in this paper can accurately represent the dynamic characteristics of the whole machine tool.

Experimental Research Regarding the Influence of Hydraulic Resistances on the Hydrostatic Guideways Stiffness

2014 ◽  
Vol 657 ◽  
pp. 475-479
Author(s):  
Marius Pascu ◽  
Gheorghe Stan
Keyword(s):  
Machine Tool ◽  
Hydraulic Resistance ◽  
Experimental Research ◽  
Machine Tools ◽  
Dynamic Stiffness ◽  
Experimental Results ◽  
Graphical Form ◽  
Experimental Setup ◽  
Experimental Database ◽  
Supply Circuit

A very important factor for the hydrostatic guideways is given by the presence of the restrictor on the supply circuit, whose hydraulic resistance may have important effects on the lubricant film behaviour and implicitly, on the static and dynamic stiffness of the system. This paper presents a new method of experimental research regarding the hydrostatic guideway stiffness, depending on the hydraulic resistances values which supply each pocket. During the experiments which approach the influence of the hydraulic resistances values of the restrictors on the hydrostatic guideway stiffness, a centered constant loads of 20, 50 and 100 [daN] was used. The experiments were carried out on an experimental setup composed of an open hydrostatic guideway, having the pocket dimensions of 150x88 [m, supplied with liquid under pressure through means of a pack of adjustable restrictors. The obtained experimental results are presented in both tabular and graphical form and constitute an experimental database which can be used by the machine tools designers and manufacturers. The paper contains recommendations regarding the usage of hydraulic resistances values depending on the machine tool type and size. Also, from the obtained results, recommendations can be made with regard to the type of restrictors to be used, so that the lubricant filtration grade is comprised between admissible values.

scholarly journals INVESTIGATION OF NOISE TRANSMISSION OF A MACHINE TOOL ENCLOSURE

2019 ◽  
Vol 19 (3) ◽  
pp. 5-17
Author(s):  
Friedrich BLEICHER ◽  
Christoph REICHL ◽  
Felix LINHARDT ◽  
Peter WIMBERGER ◽  
Christoph HABERSOHN ◽  
...  
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Dynamic Stiffness ◽  
Measuring Method ◽  
Work Piece ◽  
Noise Emission ◽  
Mechatronic Systems ◽  
Major Interest ◽  
Noise Transmission ◽  
Moving Parts

Machine tools are highly integrated mechatronic systems consisting of dedicated mechanic design and integrated electrical equipment - in particular drive systems and the CNC-control - to realize the complex relative motion of tool towards work piece. Beside the process related capabilities, like static and dynamic stiffness as well as accuracy behavior and deviation resistance against thermal influence, safety aspects are of major interest. The machine tool enclosure must fulfill multiple requirements like retention capabilities against the moving parts of broken tools, lose work pieces or clamping components. In regular use, the noise emission have to be inhibited at the greatest possible extent by the machine tool enclosure. Nevertheless, the loading door and the moving parts of the workspace envelope are interfaces where noise transmission is harder to be avoided and therefore local noise emissions increase. The aim of the objective investigation is to analyse the noise emission of machine tools to determine the local noise transmission of a machine tool enclosure by using arrays of microphones. By the use of this measuring method, outer surfaces at the front, the side and on the top of the enclosure have been scanned. The local transient acoustic pressures have been recorded using a standard noise source placed on the machine table. In addition, an exemplary manufacturing process has been performed to analyse the frequency dependent location resolved sound emissions.

Design Optimization of a Beam Structure of Machine Tools

2019 ◽  
Author(s):  
Necmettin Kaya ◽  
M. Onur Genç
Keyword(s):  
Topology Optimization ◽  
Machine Tool ◽  
Machine Tools ◽  
Laser Cutting ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Optimization Technique ◽  
Beam Structure ◽  
Maximum Displacement ◽  
Cutting Machine

Abstract In order to improve the dynamic behavior and cutting accuracy of an industrial laser cutting machine tool, a new beam structure was designed using topology optimization technique. Beams hold the cutting head and laser beam mirrors of laser cutting machine tools. Weight, static and dynamic stiffness of the beam affect the dynamic performance of the machine tool. High weight and low dynamic stiffness in high acceleration and deceleration will result in the vibration of the machine body. In this paper, a new beam is designed using topology optimization to reduce the weight of the beam structure. Static stiffness and natural frequencies were obtained by finite element analyses. The mass reduction obtained was 18%, the maximum displacement is reduced by 13% and the first natural frequency of beam is increased by 29 % in comparison to the original beam. Also the use of aluminum instead of steel was examined and the results are compared.

Structure Analysis and Optimum Design of NC Grinding Machine Tool Bed

2011 ◽  
Vol 80-81 ◽  
pp. 909-912 ◽  
Author(s):  
Xing Wei Sun ◽  
Jun Wang ◽  
Xin Feng ◽  
Ke Wang
Keyword(s):  
Finite Element ◽  
Machine Tool ◽  
Design Method ◽  
Dynamic Stiffness ◽  
Element Model ◽  
Technology Support ◽  
Advanced Level ◽  
Grinding Machine ◽  
Nc Grinding ◽  
Element Theory

The modern design method based on the finite element theory has become the essential means of present machine design. In this paper, dynamics finite element model of NC grinding machine tool’s bed has been established with the finite element analytic technique. Dynamic characteristic of processing has been studied. The optimization program of structure to lower the vibratory response has been designed. This advances the dynamic stiffness of bed. This research provides an essential theory and technology support for achieving the advanced level of the international similar machine tool on the aspect of machining precision, reliability and security.

scholarly journals Cast Iron And Mineral Cast Applied For Machine Tool Bed - Dynamic Behavior Analysis

2015 ◽  
Vol 60 (2) ◽  
pp. 1023-1029 ◽  
Author(s):  
N. Kępczak ◽  
W. Pawłowski ◽  
Ł. Kaczmarek
Keyword(s):  
Cast Iron ◽  
Machine Tool ◽  
Machine Tools ◽  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Structural Elements ◽  
Static Structure ◽  
Static Rigidity

Abstract Cast iron and mineral cast are the materials most often used in the machine structural elements design (bodies, housings, machine tools beds etc.). The materials significantly differ in physical and mechanical properties. The ability to suppress vibration is one of the most important factors determining the dynamic properties of the machine and has a significant impact on the machining capabilities of a machine tool. Recent research and development trends show that there is a clear tendency to move away from the traditional iron casting to the mineral casting, due to better dynamic properties of the latter. However mineral cast as a structural material for the whole machine tools bed turns out to be insufficient due to its poor mechanical strength properties. The best solution should benefit from the advantages of the cast iron and mineral cast materials while minimizing their drawbacks. The paper presents numerical modal analysis of two lathe beds: the first one made of gray cast iron and the second one made of hybrid connection of cast iron and mineral cast. The analysis was conducted in order to determine the dynamic properties of two bodies of similar shapes made in the traditional (cast iron) and innovative hybrid (cast iron and mineral cast) technology. In addition, an analysis of the static structure rigidity of the two beds was performed. During the simulation studies it was found a significant increase in dynamic stiffness and static rigidity of the machine tool body made of hybrid connection of cast iron and mineral cast. The results of numerical simulations have confirmed the desirability of using hybrid construction because the dynamic properties of such a body are more advantageous in comparison with the conventional body made of cast iron.

Development of a Virtual Axis Cutter Grinder

2006 ◽  
Vol 304-305 ◽  
pp. 483-487
Author(s):  
Xian Guo Han ◽  
Wu Yi Chen ◽  
B. Huang ◽  
Shao Hong Wang
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Design Method ◽  
Parallel Machine ◽  
Design Parameters ◽  
Good Precision ◽  
Program System ◽  
Parallel Machine Tools ◽  
Parallel Machine Tool ◽  
New Machine

The development of a virtual axis cutter grinder was introduced. The main contents of this paper include layout design, parameters design method, control system and program system. The purpose of the development of the parallel machine tools is for cutter grinding. The dimension of the cutter and the translation workspace for cutter grinding usually is small and is therefore suitable for the parallel machine tool application. The new machine tool has high rigidity and good precision.

Optimum Size Consideration of Machine Tools

2007 ◽  
Vol 339 ◽  
pp. 337-342 ◽  
Author(s):  
N. Mishima
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Design Method ◽  
Design Guidelines ◽  
Design Tool ◽  
Design Parameters ◽  
Error Sources ◽  
Machine Performance ◽  
Small Machine ◽  
Tool Performance

As has been demonstrated in the “microfactory” which is a miniature manufacturing system proposed by the author’s research group, small machine tools that are comparable in size to their target products lead to large reductions in energy consumption and area. Experiments showed that they were capable of micro mechanical fabrication. However, the design of miniature machine tools has not been fully optimized. The author proposed a design method to estimate machine tool performance. In this paper, the design tool is applied to find miniaturizing strategies. By applying the design tool, it is possible to determine which of the design parameters and error sources would significantly affect machine performance. From the results of calculation, the tool can clarify the effect of machine tool sizes imposed on the machine performances. This leads to some suggestions regarding machine tool sizes. Finally, design guidelines for miniature machine can be obtained.

scholarly journals THERMAL STIFFNESS – A KEY ACCURACY INDICATOR OF MACHINE TOOLS

2021 ◽  
Vol 2021 (3) ◽  
pp. 4548-4555
Author(s):  
A. P. Kuznetsov ◽  
◽  
H. J. Koriath ◽  
Keyword(s):  
Machine Tool ◽  
Thermal Behavior ◽  
Thermal Energy ◽  
Machine Tools ◽  
Dynamic Stiffness ◽  
Structural Formula ◽  
Linear Expansion Coefficient ◽  
Thermoelastic Properties ◽  
Active Elements ◽  
Thermal Link

Static and dynamic stiffness [N/m] determine the ability of solids to resist constant and variable loads. Both elastic characteristics of a machine tool effect their quality assessment. Thermal stiffness (comprising heat stiffness and temperature stiffness) [W/µm] is a key accuracy indicator of the machine tool's ability to resist temperature influences. The proposed method creates the thermo-physical structure of a machine tool, based on a set of homogeneous heat-active elements and quasi-thermostable links. Quasi-thermostable links retain constant properties when the thermal state of the heat-active elements changes within a given range, building and determining their spatial and temporal relative position. The structural formula is given: < S-thermal link > -<F-function of the thermal behavior of a heat-active element > - <S-thermal link>. When exposed to heat, heat-active elements change their temperature and thermoelastic properties change their temperature and thermoelastic properties with stress, strain, distortion. Thermal behavior F-functions characterize these changes over time. Thermal energy causes a heat exchange in the machine tool and leads to temperature differences, thermoelastic stresses and geometrical deformations. The material used in machine tools enables the thermal conduction, convection and radiation due to its dimensions, volume and surface area, thermal conductivity. Elasticity effects base on thermal linear expansion coefficient, modulus of elasticity, thermal energy storage due to its heat capacity. The analysis of the structural formula defines and describes generalized thermal stiffness indicators of a machine tool as a reaction to thermal effects when the heat sources are constantly active and when the heat source is absent, but only the ambient temperature changes. This paper presents relationships between the thermal stiffness and the thermo-physical property indicators of the machine tool. Examples of thermal stiffness are described for several machine tool types.

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