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.

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.

Influence of Bolted Joint on Dynamic Characteristics of Combined Three-Section Crossbeam

2010 ◽  
Vol 37-38 ◽  
pp. 534-539
Author(s):  
Tie Neng Guo ◽  
Dong Liang Guo ◽  
Li Gang Cai ◽  
Bin Song ◽  
Jing Nan Zhao
Keyword(s):  
Machine Tool ◽  
Dynamic Analysis ◽  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Bolted Joints ◽  
Experimental Result ◽  
Bolted Joint ◽  
Cnc Milling ◽  
Characteristic Parameters

The combined three-section crossbeam is an important component in the heavy gantry CNC milling-lathing machine tool and the dynamic characteristics are key precision factors for the machine tool. Three sections of the combined crossbeam are bolted by large industrial bolts and the influence of bolted joints should be evaluated in the dynamic analysis of the combined crossbeam. The dynamic characteristics of the combined three-section crossbeam were extracted by the modal experiment. The FEM of the monolithic crossbeam was modeled to analyze the dynamic characteristic parameters. The comparison of the analysis result and experimental result were shown. The experimental result matched well with the FEM of the monolithic crossbeam without bolted joints. As a result, the influence of the bolted joints could be ignorable in dynamic characteristic for the combined three-section crossbeam.

Method of Improvement in Identification Accuracy of the Dynamic Characteristics of Joints in Jointed Structure

2012 ◽  
Vol 523-524 ◽  
pp. 451-456
Author(s):  
Shinji Shimizu ◽  
Yoshiaki Kabaya ◽  
Haruhisa Sakamoto ◽  
Kenichi Yamashita
Keyword(s):  
Dynamic Characteristic ◽  
Influencing Factors ◽  
Dynamic Characteristics ◽  
Vibration Mode ◽  
Relative Displacement ◽  
Identification Accuracy ◽  
Characteristic Parameters ◽  
Characteristic Values

In this study, we examined influencing factors on the identification accuracy and improving method of the identification accuracy. As a result, the influence of the condition of the dynamic characteristic values is large and these values should correspond to the tangential and vertical directions. The influence of treating dynamic characteristic parameters of the same plural joints is also large, and then the parameters of the same plural joints should have the same value. In addition, the tangential dynamic characteristics should be identified from the vibration mode which has large tangential relative displacement between the joint interfaces. Similarly, the vertical one should be identified from the vibration mode which has large vertical relative displacement between the joint interfaces. Finally, the identification accuracy can be improved greatly by considering these influences.

Identification Method of Dynamic Characteristics of Joints in Jointed Structures

2013 ◽  
Vol 7 (2) ◽  
pp. 221-227
Author(s):  
Shinji Shimizu ◽  
◽  
Yoshiaki Kabaya ◽  
Haruhisa Sakamoto ◽  
Kenichi Yamashita ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Transfer Function ◽  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Vibration Mode ◽  
Joint Model ◽  
Characteristic Parameters ◽  
Element Analysis ◽  
Spring Element

In this paper, we propose a method of identifying the dynamic characteristics of joints in jointed structures. We first consider a joint model for finite element analysis. We then propose, based on the consideration, a method of identifying dynamic characteristic parameters of the joint, such as the spring stiffness and damping coefficient, with the joint model. As a result, we obtain a joint model with the spring and damping elements in vertical and tangential directions between a pair of nodes with changeable numbers and locations. The number and location of these elements can be determined so that the vibration mode and the inertance transfer function of the jointed structure obtained from finite element analysis with infinite stiffness of the spring element agree with those of the structure without joints. In addition, we identify the dynamic characteristic parameters of the joint so the experimental inertance transfer function and vibration mode agree with those obtained from the finite element analysis.

Research on the Dynamic Characteristics of NC Boring Machine Spindle System Based on Finite Element Analysis

2013 ◽  
Vol 819 ◽  
pp. 71-75
Author(s):  
Feng Jiao ◽  
Guang Ming Sun ◽  
Jian Hui Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Characteristics ◽  
Hydrodynamic Lubrication ◽  
Dynamic Stiffness ◽  
Element Analysis ◽  
Spindle System ◽  
Machine Performance ◽  
Machine Spindle ◽  
The Impact

In this paper, elastic hydrodynamic lubrication theory was introduced into bearing dynamic stiffness calculation process to take into account the impact of the oil film on the rolling stiffness. Dynamic characteristics of NC boring machine spindle system dedicated to the manufacturing of bearing retainer were studied based on finite element analysis software. The rationality of the structural design of spindle was verified in the paper. The research provided a theoretical basis for the improvement of machine performance and dynamic design of NC boring machine spindle.

scholarly journals Study on Dynamic Characteristics of Aerostatic Bearing with Elastic Equalizing Pressure Groove

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xiao-long Zhao ◽  
Hao Dong ◽  
Zhou Fang ◽  
Deng-di Chen ◽  
Jun-an Zhang
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Coupling Model ◽  
Damping Coefficient ◽  
Aerostatic Bearing ◽  
Equivalent Damping ◽  
New Type ◽  
Equivalent Damping Coefficient ◽  
Control Equation

Microvibration has an important influence on the dynamic performance of aerostatic bearings. Dynamic stiffness and equivalent damping coefficient are the main indexes to evaluate the dynamic characteristics of the aerostatic bearing. In order to study the dynamic characteristics of a new type of aerostatic bearing with the elastic equalizing pressure groove (EEPG), the dynamic characteristics of the new type of bearing are studied by theoretical calculation and experiment. First, the dynamic gas-solid coupling control equation is established. Then, the steady term and the perturbation term are decomposed by the perturbation method. By solving the coupling model, the dynamic characteristics of the bearing are calculated and analyzed. The calculation results show that the perturbation frequency has a significant effect on the dynamic stiffness and equivalent damping coefficient of the aerostatic bearing with EEPG. The dynamic stiffness increases with the increase of frequency, and the equivalent damping coefficient decreases with the increase of frequency. The experimental results are basically the same with the theoretical results, which effectively verify the correctness of the theoretical analysis.

Dynamic Characteristic of HSK Tooling System

2006 ◽  
Vol 315-316 ◽  
pp. 440-444
Author(s):  
Gui Cheng Wang ◽  
S.L. Wang ◽  
Hong Jie Pei ◽  
Wei Guo Wu ◽  
X.J. Hua
Keyword(s):  
Dynamic Characteristic ◽  
Rotational Speed ◽  
High Speed ◽  
Dynamic Stiffness ◽  
Loading Capacity ◽  
High Speed Machining ◽  
Depth Analysis ◽  
Tooling System ◽  
The Relationship ◽  
High Speed Machine

According to in-depth analysis of the interface between HSK shank and the spindle, the dynamic characteristic of HSK tool system in high speed machining is studied and numerical simulation is carried out with FEM. The HSK tool system deformation, contact stress and the change law of dynamic stiffness were opened out systematically. The relationship between the dynamic stiffness and loading capacity was given. The rotational speed per minute when HSK taper coordination position fails can be named limit maximum rotational speed Nmax of HSK. This provides the foundation for the design of the high speed machine tool.

scholarly journals Analysis of the dynamic characteristics of downsized aerostatic thrust bearings with different pressure equalizing grooves at high or ultra-high speed

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110180
Author(s):  
Ruzhong Yan ◽  
Haojie Zhang
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Rotation Speed ◽  
Dynamic Stiffness ◽  
Simulation Method ◽  
Perturbation Amplitude ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Ultra High Speed ◽  
Air Film

This study adopts the DMT(dynamic mesh technology) and UDF(user defined functions) co-simulation method to study the dynamic characteristics of aerostatic thrust bearings with equalizing grooves and compare with the bearing without equalizing groove under high speed or ultra high speed for the first time. The effects of air film thicness, supply pressure, rotation speed, perturbation amplitude, perturbation frequency, and cross section of the groove on performance characteristics of aerostatic thrust bearing are thoroughly investigated. The results show that the dynamic stiffiness and damping coefficient of the bearing with triangular or trapezoidal groove have obvious advantages by comparing with that of the bearing without groove or with rectangular groove for the most range of air film thickness, supply pressure, rotation speed, perturbation amplitude, especially in the case of high frequency, which may be due to the superposition of secondary throttling effect and air compressible effect. While the growth range of dynamic stiffness decreases in the case of high or ultra-high rotation speed, which may be because the Bernoulli effect started to appear. The perturbation amplitude only has little influence on the dynamic characteristic when it is small, but with the increase of perturbation amplitude, the influence becomes more obvious and complex, especially for downsized aerostatic bearing.

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