Contact stiffness of machine tool joints

1975 ◽  
Vol 8 (1) ◽  
pp. 9-14 ◽  
Author(s):  
P.P. Chikate(Mech.) ◽  
S.K. Basu
Keyword(s):  
Machine Tool ◽  
Contact Stiffness

scholarly journals Analysis on Dynamic Contact Characteristics and Dynamic Stiffness Estimating Method of Single Nut Ball Screw Pair Based on the Whole Rolling Elements Model

2020 ◽  
Vol 10 (17) ◽  
pp. 5795
Author(s):  
Ye Chen ◽  
Chunyu Zhao ◽  
Zhenjun Li ◽  
Zechen Lu
Keyword(s):  
Machine Tool ◽  
Mass Production ◽  
Contact Stiffness ◽  
Dynamic Stiffness ◽  
Dynamic Contact ◽  
Ball Screw ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Feed System ◽  
Stiffness Model

The purpose of this paper is investigating the characteristics of dynamic contact and dynamic stiffness of the single nut ball screw pair (SNBSP). Then a new sensorless method is proposed to extract the SNBSP dynamic contact stiffness of a mass production CNC machine tool feed system. First of all, the transformation relationship between each coordinate system of SNBSP is established. Secondly, the dynamic model of all ball–raceway contact pairs is established. Based on this, a dynamic contact stiffness model is established. The dynamic contact parameters are obtained by the numerical method. It is found that the influence of screw speed on screw and nut raceway normal force distribution are opposite. This will affect the variations of dynamic contact stiffness. It is also clear that the effect of axial load on dynamic stiffness is significant. Then, an effective method is proposed to estimate the dynamic contact stiffness of a mass production CNC machine tool feed system without any external sensors. The axial force of feed system is estimated by using torque current of servo motor. Current signals can be obtained through FANUC Open CNC API Specifications (FOCAS) library functions, and then dynamic contact stiffness can be calculated through the stiffness model without external sensors. Finally, a feed system dynamic model is built, and the contact model and sensorless stiffness estimating method are verified by experiments in this dynamic system.

The Vibration Characteristic Analysis of Feed System of CNC Machine Tool

2013 ◽  
Vol 482 ◽  
pp. 169-173
Author(s):  
Qin Wu ◽  
Jian Jun Yang
Keyword(s):  
Machine Tool ◽  
Lagrange Equation ◽  
Contact Stiffness ◽  
Ball Screw ◽  
Cnc Machine Tool ◽  
Test Bed ◽  
Cnc Machine ◽  
Characteristic Analysis ◽  
Feed System ◽  
Vibration Displacement

The mathematical model of feed system of CNC machine tool was established base of Lagrange Equation and energy principle, then uses the Runge-Kutta method to solve the equation, and analyzes the influence that the parameters to the vibration displacement of ball screw. According to the result of orthogonal test, it is concluded that the most important three factors which influence ballscrew vibration displacement were the ball screw's lead h, the table quality m and the longitudinal contact stiffness kn in the connection of workbench and ballscrew. On the feed system test-bed, the longitudinal amplitude, torsional amplitude and horizontal amplitude of ball screw were measured, the results show the larger the ball screw's lead and the quality of workbench, the greater the amplitude of ball screw, the bigger the longitudinal contact stiffness kn, and the smaller the amplitude of screw.

A Prediction Method for Dynamic Performance of Machine Tool Joint Surfaces

2013 ◽  
Vol 437 ◽  
pp. 8-12
Author(s):  
Yao Yang ◽  
Jun Tang Yuan ◽  
Zhen Hua Wang ◽  
Biao Yang
Keyword(s):  
Finite Element ◽  
Machine Tool ◽  
Contact Stiffness ◽  
Dynamic Performance ◽  
Prediction Method ◽  
Element Model ◽  
Multiple Point ◽  
Material Layer ◽  
Joint Surfaces ◽  
Relative Errors

The method for dynamic modeling of joint surfaces is proposed to predict dynamic performance of machine tool accurately by virtual material layer elements in this paper. For this process, the numerical relations of contact stiffness and virtual material layer parameters are obtained by finite element theory, and the finite element model is founded by virtual material layer elements and multiple point constrain technique (MPC). Modal analysis of a simple model under different contact stiffness is carried out. It has shown the relative errors between theoretical natural frequencies and simulated ones of this model are less than 2%.

Measurement of Contact Stiffness for Stiffness Estimation of Machine Tool Supports

2012 ◽  
Vol 523-524 ◽  
pp. 457-462 ◽  
Author(s):  
Daisuke Kono ◽  
Takahiro Inagaki ◽  
Atsushi Matsubara ◽  
Iwao Yamaji
Keyword(s):  
Machine Tool ◽  
Measurement Method ◽  
Contact Stiffness ◽  
Tool Support ◽  
Normal Contact ◽  
Tangential Contact ◽  
Longitudinal Elastic Modulus ◽  
Normal Contact Stiffness ◽  
Elastic Shear ◽  
Unit Normal

The contact stiffness is measured at interfaces of several materials that are often used for the machine tool support. Models of machine tool supports and contact stiffness are described. Then, a measurement method of the contact stiffness is proposed according to the model and demonstrated. The unit normal contact stiffness is 1-2×106 N/mm/mm2 for general steel and cast iron. The unit normal contact stiffness is pSuperscript textositively correlated with the longitudinal elastic modulus. The unit tangential contact stiffness is 1/10-1/5 of the unit normal contact stiffness and not correlated with the elastic shear modulus. The surface roughness of the specimen should be small to reduce the dispersion of the measured unit contact stiffness.

Evaluating Mobile Machine Tool Dynamics by Substructure Synthesis

2014 ◽  
Vol 1018 ◽  
pp. 373-380 ◽  
Author(s):  
Mohit Law ◽  
Hendrik Rentzsch ◽  
Steffen Ihlenfeldt
Keyword(s):  
Machine Tool ◽  
Contact Stiffness ◽  
A Priori ◽  
Numerical Verification ◽  
Combined System ◽  
Response Characteristics ◽  
Dynamic Substructuring ◽  
Tool Dynamics ◽  
Stiffness And Damping ◽  
Mobile Machine

Mobile machining solutions use autonomous machining units that can be transported to different part locations, making possible easy maintenance and repair of large industrial equipment. Every new part and location results in different boundary conditions for the mobile machine tool-part system; influencing the dynamics of the combined system and necessitating different strategies for part/machine referencing and clamping. To facilitate efficient mutability and modularity in mobile machining solutions, this paper presents a dynamic substructuring strategy that combines the response characteristics of the mobile machine unit with that of two different simulated base models under varying levels of contact stiffness and damping to obtain the synthesized mobile machine tool dynamic response. Numerical verification of the approach is provided. Framework presented can also combine measured response of parts for which models may not be available a priori. Methods presented provide experimental guidelines for establishing strategies for part/machine referencing, and planning of machining strategies based on the evaluated dynamics.

A Hybrid Contact Implementation Framework for Finite Element Analysis and Topology Optimization of Machine Tools

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Esra Yuksel ◽  
Ahmet Semih Erturk ◽  
Erhan Budak
Keyword(s):  
Finite Element ◽  
Topology Optimization ◽  
Structural Optimization ◽  
Machine Tool ◽  
Machine Tools ◽  
Optimization Problem ◽  
Optimization Problems ◽  
Contact Stiffness ◽  
Contact Forces ◽  
Implementation Framework

Abstract Machine tool contacts must be represented accurately for reliable prediction of machine behavior. In structural optimization problems, contact constraints are represented as an additional minimization problem based on computational contact mechanics theory. An accurate contact constraint representation is challenging for structural optimization problems: (i) “No penetration” rule dictated by Hertz-Signorini-Moreau (HSM) conditions at contacts is satisfied by varying the contact stiffness during a finite element (FE) solution without control of a user which causes increased contact stiffness “erroneously” to avoid penetration of contacting node pairs in an FE solution; and (ii) the reliability of solutions varies according to the chosen computational contact method. This paper is devoted to the topology optimization of machine tools with contact constraints. A hybrid approach is followed that combines the computational contact problem framework and an obtained stable contact stiffness function (analytically or experimentally). According to the proposed method, the existing optimization problem in FE literature is restated in a reliable form for machine tool applications. To avoid the existing computational challenges and reliability problems, contact forces are directly mapped onto an FE model used in the restated topology optimization problem with the help of proposed method. In this study, the existing and the proposed methods for contact are investigated by means of the solid isotropic material with penalization model (SIMP) algorithm for topology optimization. The effectiveness of the proposed method is demonstrated by comparing the experimental measurements on a prototype machine tool manufactured according to the optimization solutions of the proposed method and those of a conventional machine tool.

scholarly journals Stiffness model of machine tool supports using contact stiffness

2013 ◽  
Vol 37 (3) ◽  
pp. 650-657 ◽  
Author(s):  
Daisuke Kono ◽  
Takahiro Inagaki ◽  
Atsushi Matsubara ◽  
Iwao Yamaji
Keyword(s):  
Machine Tool ◽  
Contact Stiffness ◽  
Stiffness Model
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