Change in Dynamic Characteristics of Spindle for Machining Centers Caused by Chucking Mechanism of Clamped Toolholders

2012 ◽  
Vol 523-524 ◽  
pp. 521-526 ◽  
Author(s):  
Haruhisa Sakamoto ◽  
Yuhei Maeki ◽  
Shinji Shimizu
Keyword(s):  
Dynamic Characteristics ◽  
Transfer Functions ◽  
Dynamic Stiffness ◽  
Characteristic Parameters ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Machining Center ◽  
Vibration Model ◽  
Order Of Magnitude ◽  
Response Method

In this study, the effects of clamping toolholders on the dynamic characteristics of spindle systems are evaluated experimentally. In the experiments, the transfer functions are obtained by the impulse response method, and then, the dynamic characteristic parameters are identified based on the vibration model of single-degree of freedom. Two types of machining center spindles and four types of toolholders are evaluated. From the experimental results, the following are revealed: (1) the clamping toolholder enhances the vibration amplitude markedly compared with that of the spindle not clamping toolholder. (2) The different chucking mechanisms clearly change the dynamic stiffness of the spindle systems. (3) The order of magnitude of the dynamic stiffness of the spindle systems agrees well with that of the isolated toolholders. It is confirmed experimentally that clamping of the appropriate toolholder improves the dynamics stiffness of the spindle systems for machining centers.

Effect of Clamped Toolholders on Dynamic Characteristics of Spindle System of Machining Center

2012 ◽  
Vol 6 (2) ◽  
pp. 168-174 ◽  
Author(s):  
Haruhisa Sakamoto ◽  
◽  
Taiga Matsuda ◽  
Shinji Shimizu ◽  
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Physical Parameters ◽  
Characteristic Parameters ◽  
Spindle System ◽  
Press Fit ◽  
Equivalent Damping Coefficient ◽  
Response Method ◽  
Tooling System

In this study, dynamic characteristics are determined based on the impulse response method, the correction of discretization errors and the identification of equivalent physical parameters, as found in the vibration model having one degree of freedom. In the experiments, the test tool is cylindrical bar shaped and made from solid tungsten carbide, and four toolholders with chucking mechanisms, including the shrinkfit type, collet type, hydraulic type, and press-fit type, are used. Since it had been previously confirmed that one of the tool preparation jigs had dynamic characteristics similar to those of an actual machine tool’s spindle, the dynamic characteristics of the jig could be measured the way the spindle system is measured in this study. From the experimental examinations, the following were clarified. (1) Chucking of the tooling system enhances the first mode vibration of the spindle system markedly. (2) The type of tool chuck used changes the dynamic characteristics of the spindle system. The trend in the dynamic stiffness corresponds well with that in the equivalent damping coefficient but is opposite to that in the equivalent stiffness. (3) The magnitude order of the dynamic characteristic parameters of the spindle system corresponds well with the inherent values of the dynamic characteristic parameters of the toolholders themselves; that is, the inherent dynamic characteristics of the tooling system can be used as the criteria to estimate the effect on the dynamic characteristics of the spindle system.

An Eigenvalue Inclusion Principle for Simple, Rotationally Periodic Structures

1993 ◽  
Author(s):  
I. Y. Shen
Keyword(s):  
Linear Combination ◽  
Periodic Structure ◽  
State Vector ◽  
Transfer Functions ◽  
Periodic Structures ◽  
The State ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Inclusion Property ◽  
Single Degree

Abstract This paper describes an eigenvalue inclusion principle for a simple, rotationally periodic structure P whose i-th substructure Si is connected to a neighboring substructure Si+1 through a single-degree-of-freedom interface constraint Ii+1. The state vector vi+1 at the interface Ii+1, consisting of the displacement and the force at the interface, is represented in terms of the state vector vi at the interface Ii through transfer functions of the substructure Si. The periodicity of the structure P then requires that a linear combination of the transfer functions of Si be zero. As a consequence, a simple periodic structure P with period N will have exactly N eigenvalues lying between two consecutive eigenvalues of the substructure Si. Finally, this eigenvalue inclusion property is illustrated on a periodic structure with known exact eigensolutions.

Effectiveness of neoprene pad vibration isolators at high frequencies

2021 ◽  
Vol 263 (4) ◽  
pp. 2172-2183
Author(s):  
Jerry Lilly
Keyword(s):  
Natural Frequency ◽  
Insertion Loss ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Frequency Wave ◽  
Single Degree Of Freedom ◽  
High Frequencies ◽  
Vibration Isolators ◽  
Single Degree ◽  
Wide Range

The natural frequency, dynamic stiffness, and insertion loss of commercially available neoprene pad vibration isolators have been measured in a simple, single degree of freedom system over a wide range of pad loadings out to a maximum frequency of 10 kHz. The results reveal that dynamic stiffness can vary significantly with pad loading as well as the durometer of the material. It will also be shown that insertion loss follows the theoretical single degree of freedom curve only out to a frequency that is about 5 to 10 times the natural frequency, depending upon the pad durometer rating. Above that frequency wave resonances in the material cause the insertion loss to deteriorate significantly out to a frequency near 1 kHz, above which the insertion loss maintains a relatively constant value, again depending upon the pad durometer rating. In some instances the insertion loss values can approach 0 dB or even become negative at specific frequencies in the frequency region that is 10 to 20 times the natural frequency of the system.

3-DOF Outer Rotor Electromagnetic Spherical Actuator

2016 ◽  
Vol 10 (4) ◽  
pp. 591-598 ◽  
Author(s):  
Yusuke Nishiura ◽  
◽  
Katsuhiro Hirata ◽  
Yo Sakaidani ◽  
Keyword(s):  
Genetic Algorithm ◽  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Single Degree Of Freedom ◽  
Torque Density ◽  
Multiple Degrees Of Freedom ◽  
Single Degree ◽  
Outer Rotor ◽  
High Torque ◽  
Spherical Actuator

Conventionally, many single-degree-of-freedom (single-DOF) actuators have been used to realize devices with multiple-degrees-of-freedom (multi-DOF). However, this makes their structures larger, heavier, and more complicated. In order to remove these drawbacks, the development of spherical actuators with multi-DOF is necessary. In this paper, we propose a new 3-DOF outer rotor electromagnetic spherical actuator with high torque density and wide rotation angles. The dynamic characteristics are computed employing 3-D FEM and its effectiveness is verified by carrying out measurements on a prototype. Then, in order to realize further high torque density, the electromagnetic pole arrangement is optimized using Genetic Algorithm (GA) and the effectiveness of the optimized stator poles arrangement is verified.

The Determination of Dynamic Stiffness of Dish-Shaped Metal Corrugated Pipe by Use of Random Vibration Method

2012 ◽  
Vol 468-471 ◽  
pp. 1393-1397
Author(s):  
Li Ming Rui ◽  
Mei Sheng Zheng ◽  
Lian Jun Tian
Keyword(s):  
Random Vibration ◽  
Dynamic Stiffness ◽  
Static Stiffness ◽  
Mass System ◽  
Single Degree Of Freedom ◽  
Vibration Method ◽  
Single Degree ◽  
Wide Range ◽  
Random Vibration Method

This paper simplifies the dish-shaped metal corrugated pipe into a elastic element, constitutes a single degree of freedom spring-mass system, then applicants the random vibration method to measure its natural frequency, further to calculate the dynamic stiffness of dish-shaped metal corrugated pipe. At the same time its static stiffness test is done. By comparison of two results, static and dynamic stiffness values fit well, and dynamic stiffness is closer to the actual working conditions. Random vibration method for dynamic stiffness is convenient, accurate and has application values in a wide range of engineering.

Dynamic analysis of a ball screw feed system with time-varying and piecewise-nonlinear stiffness

2019 ◽  
Vol 233 (18) ◽  
pp. 6503-6518 ◽  
Author(s):  
Jianguo Gu ◽  
Yimin Zhang
Keyword(s):  
Dynamic Characteristics ◽  
Ball Screw ◽  
Time Varying ◽  
Feed System ◽  
Restoring Force ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Nonlinear Restoring Force ◽  
Abrupt Changes ◽  
Screw Feed

In this study, a single-degree-of-freedom model is established to investigate the dynamic characteristics of a single-nut double-cycle ball screw feed system by considering the contact states of the nonlinear kinematic joints. Based on fully considering the parameters of the ball screw feed system, the axial deformations and forces of the key components are calculated to construct a set of piecewise-nonlinear restoring force functions of the system displacement and worktable position. The variations of the contact stiffnesses of the kinematic joints and transmission stiffness of the system with different boundary conditions are analyzed and the results indicate that they all have abrupt changes when the system displacement reaches a critical value. The changing law of the system transmission stiffness in the whole stoke is discussed. Additionally, the effects of excitation force, worktable position and system mass on the dynamic characteristics of the system and its correlative components are analyzed.

Modeling and Load Capacity Analysis of Reciprocating Hybrid Linear Guideway With Annular Groove and Sloped Recesses

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Huanyu Du ◽  
Hongguang Li ◽  
Guang Meng
Keyword(s):  
Dynamic Characteristics ◽  
Normal Vibration ◽  
Linear Time ◽  
Load Capacity ◽  
Normal Direction ◽  
Capacity Analysis ◽  
Time Varying ◽  
Bearing Surface ◽  
Single Degree Of Freedom ◽  
Single Degree

Abstract In this work, we research a reciprocating hybrid linear guideway and study its load capacity. This hybrid guideway's bearing surface is designed with an annular groove and two sloped shallow recesses. The analysis is based on modeling by mass-conserving cavitation algorithm (p − θ cavitation algorithm), where a modified smoothing switch function is raised for better convergence. Focusing on the normal direction to reciprocation, the load-guideway system is simplified as a single-degree-of-freedom linear time-varying system and solved by Newmark-β method. Due to the hybrid guideway's time-varying dynamic characteristics, there is a normal vibration in reciprocation. By analyzing two typical load cases in detail, the results indicate that the hybrid guideway has greater load capacity than the hydrostatic guideway, and the normal vibration is small enough for most engineering situations.

Research on the Static and Dynamic Characteristics of the Sliding Rail Joint Surfaces of the Fe-Based Porous Oily Material

2014 ◽  
Vol 607 ◽  
pp. 422-426
Author(s):  
Jian Feng Ma ◽  
Qiang Li ◽  
Liang Sheng Wu ◽  
Chong Nian Qu
Keyword(s):  
Dynamic Characteristics ◽  
Unit Area ◽  
Test System ◽  
Joint Interface ◽  
Equivalent Stiffness ◽  
Characteristic Parameters ◽  
Single Degree Of Freedom ◽  
Joint Surfaces ◽  
Machine Tool Structures ◽  
Stiffness And Damping

The dynamic characteristics of joint interfaces have significant effect on both static and dynamic behaviors of the whole machine tool structures. A test system for identifying the unit area dynamic characteristic parameters of Fe-based joint interfaces in still and motion states were represented based on Equivalent Single Degree Of Freedom (ESDOF) system theory. Compared with the stiffness and damping parameters in stationary state, the stiffness is reduced and the damping is increased in motion. When the velocity increased, the equivalent stiffness and damping parameters of joint interface are both increased.

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