Influence of Machine Tool Covers on Feed Drives

2011 ◽  
Author(s):  
Petr Kolar ◽  
Jan Masek ◽  
Jiri Sveda ◽  
Jan Hudec
Keyword(s):  
Machine Tool ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Reaction Force ◽  
Point Of View ◽  
Feed Drive ◽  
Feed Drives ◽  
Maximum Reaction ◽  
Stiffness And Damping ◽  
Multi Body

Machine tool covers are important parts of the machine. From the point of view of feed drives, a cover is an additional multi-body system that influences the dynamic properties of the feed drive and the positioning accuracy of the machine. The advantages of covers connected to the machine table with flexible elements are shown on simulation and experimental results. A mathematical model of the cover and its connection to the machine table is described. Optimization of the stiffness and damping ratio for the connection, using a model of the cover, is suggested. The optimal connection parameters cause decreasing of maximum reaction force acting from the cover to the feed drive. This phenomenon is presented on simulation example and also on the experiment results.

Improvement of horizontal borer control system

2020 ◽  
Vol 2020 (7) ◽  
pp. 41-48
Author(s):  
Dmitriy Petreshin ◽  
Viktor Khandozhko ◽  
Andrey Dubov ◽  
German Dobrovolsky
Keyword(s):  
Control System ◽  
Machine Tool ◽  
Feed Drive ◽  
Feed Drives ◽  
System Improvement

The control system improvement of a machine-tool is considered. The necessity in control system updating is substantiated. There is shown a procedure for horizontal borer updating. A problem on adjustment of modern digital electrical feed drives is presented. A sample of electrical feed drive and NC device adjustment is presented.

scholarly journals Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System

2021 ◽  
Vol 11 (14) ◽  
pp. 6407
Author(s):  
Huiqi Liang ◽  
Wenbo Xie ◽  
Peizi Wei ◽  
Dehao Ai ◽  
Zhiqiang Zhang
Keyword(s):  
Negative Correlation ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Testing ◽  
The Body ◽  
Structural Vibration ◽  
Pedestrian Dynamics ◽  
Structure Interaction ◽  
Mass Spring ◽  
Stiffness And Damping

As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

Researches Regarding the Use of Fuzzy Controllers within CNC Feed Drives

2015 ◽  
Vol 772 ◽  
pp. 229-234
Author(s):  
Radu Eugen Breaz ◽  
Octavian Bologa
Keyword(s):  
Machine Tool ◽  
Fuzzy Controller ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Fuzzy Controllers ◽  
Feed Drive ◽  
Feed Drives ◽  
Simulation Based ◽  
Position Controller ◽  
Dc Servomotor

This paper presents some simulation based upon a dynamic model of a feed-drive within the structure of a CNC machine tool. A DC servomotor was considered as actuation device for the feed drive. For a given set of parameters for the position controller, two fuzzy types of fuzzy controllers were tested by means of simulation. The first fuzzy controller was a proportional one, with one input and one output, while the second one was a two variables one, with two inputs and one outputp.

Second Paper: An Investigation into the Mechanism of the Frictional Damping of Machine Tool Slideways

1969 ◽  
Vol 184 (1) ◽  
pp. 1088-1096 ◽  
Author(s):  
R. Bell ◽  
M. Burdekin
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Machine Tool ◽  
Instantaneous Velocity ◽  
Feed Drive ◽  
Feed Drives ◽  
Frictional Damping ◽  
Major Emphasis

The damping action of a plain slideway is considerably influenced by a number of parameters and is difficult to assess. It has been necessary, therefore, to obtain experimental data from adequately scaled experiments. The major emphasis is placed on the influence of polar additive lubricants as they offer considerable advantages in stabilizing feed drives at low feed speeds. This paper describes an investigation into the mechanism of the interaction between vibration in the direction of motion and the vibration normal to the plane of the slideway interface. Steady-state characteristics do not give an adequate guide to the damping action of a machine tool slideway. All the work discussed in this paper is restricted to vibration amplitudes that do not cause the instantaneous velocity of the feed drive to be reversed.

The twist axis of frames with particular application to motorcycles

2016 ◽  
Vol 230 (17) ◽  
pp. 3026-3039 ◽  
Author(s):  
Alberto Doria ◽  
Luca Taraborrelli
Keyword(s):  
Dynamic Properties ◽  
Critical Role ◽  
Point Of View ◽  
Experimental Results ◽  
General Definition ◽  
Hydraulic Actuator ◽  
Laser Sensors ◽  
Definition Of ◽  
Stiffness And Damping ◽  
Reference Plate

The static and dynamic properties of the frame and the front fork of a single track vehicle play a critical role from the point of view of vehicle stability. A turning point in the study of motorcycle stability was established by the introduction of lumped stiffness elements to characterize the critical compliances of the motorcycle elements, this approach being still in use with advanced multibody codes. Nonetheless, up to now very few scientific studies have been carried out to identify the parameters that account for the stiffness and damping properties of motorcycle front forks and frames. This work addresses the problem of identifying the parameters needed for developing lumped element models of motorcycles from experimental results. Two motorcycle frames are studied performing static, dynamic, and modal tests by means of a specific testing equipment. The frames have been tested in two different conditions: fixing them at the steering head or at the swing-arm pivot. In the first section of the paper a general definition of the twist axis, based on the concept of “Mozzi” or instantaneous screw axis, is presented. The twist axis is used for characterizing the deformation patterns of the tested frames. The static twist axis is identified loading the frames at low rate by means of a servo-hydraulic actuator and measuring the deformation of a reference plate by means of three laser sensors; the dynamic twist axis is identified exerting an impulsive excitation and measuring the vibration of a reference plate by means of three accelerometers. In the last section of the paper, experimental results obtained on motorcycle frames are shown. A method to identify the stiffness properties of the frames from the measured twist axes is presented. Results obtained with the proposed method are in good agreement with the ones presented in literature.

scholarly journals Dynamic Properties of Pretreated Rubberized Concrete under Incremental Loading

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2183
Author(s):  
Aijiu Chen ◽  
Xiaoyan Han ◽  
Zhihao Wang ◽  
Tengteng Guo
Keyword(s):  
Stress Level ◽  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Rubberized Concrete ◽  
Rubber Content ◽  
Rubber Particles ◽  
Energy Dissipation Capacity ◽  
Stiffness And Damping ◽  
Incremental Loading

Recycling scrap tyres as alternative aggregates of concrete is an innovative option. To clarify the dynamic properties of the pretreated rubberized concrete with some cumulative damage, the natural frequency, flexural dynamic stiffness, and damping ratio of the specimens under incremental stress level were investigated in this paper. The results indicated that the pretreatment of rubber particles improved the strength, ductility, and crack resistance of the rubberized concrete. The reduction of the flexural dynamic stiffness was clarified with the increase of concrete stress level. The addition of the pretreated rubber particles enhanced the concrete energy dissipation capacity during the destruction, and the specimen dissipated more energy with the increase of rubber content before its failure.

Analysis and Simulation of Screw Joint in CNC Machine Tool

2011 ◽  
Vol 141 ◽  
pp. 203-207
Author(s):  
Ya Wei Zhang ◽  
Wei Min Zhang
Keyword(s):  
Machine Tool ◽  
Fem Simulation ◽  
Cnc Machine Tools ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Feed Drive ◽  
Screw Joint ◽  
Drive Systems ◽  
Multi Body ◽  
Feed Drive System

CNC machine tools has always screw joints in its feed drive systems; In order to obtain good performance of CNC machine tool, it is necessary to model the screw joint with more accuracy and to research its influence on the vibration characters of the feed drive system. In this paper, the screw joint is analyzed by multi-body system theory and is modeled as flexible multi-body; Its mathematical describe of constraint condition is given by the modeling of screw joint. A revise factor is introduced into the process of FEM simulation to reflect the deformation in the screw joint. By this way, the effect of deformation in the screw joint is researched in the modeling under the ANSYS circumstance, the harmonic response under considering deformation contrast to that of without deformation. From the analysis in the simulation, it is necessary to take the deformation of screw joint into account.

scholarly journals Testing and Modelling of Elastomeric Element for an Embedded Rail System

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6968
Author(s):  
Qianqian Li ◽  
Roberto Corradi ◽  
Egidio Di Gialleonardo ◽  
Stefano Bionda ◽  
Andrea Collina
Keyword(s):  
Dynamic Properties ◽  
Reaction Force ◽  
Time History ◽  
Wide Frequency Range ◽  
Equivalent Stiffness ◽  
Zener Model ◽  
Elastomeric Material ◽  
Rail System ◽  
Non Linear ◽  
Stiffness And Damping

Modelling of elastomeric elements of railway components, able to represent stiffness and damping characteristics in a wide frequency range, is fundamental for simulating the train–track dynamic interaction, covering issues such as rail deflection as well as transmitted forces and higher frequency phenomena such as short pitch corrugation. In this paper, a modified non-linear Zener model is adopted to represent the dependences of stiffness and damping of the rail fastening, made of elastomeric material, of a reference Embedded Rail System (ERS) on the static preload and frequency of its deformation. In order to obtain a reliable model, a proper laboratory test set-up is built, considering sensitivity and frequency response issues. The equivalent stiffness and damping of the elastomeric element are experimentally characterised with force-controlled mono-harmonic tests at different frequencies and under various static preloads. The parameters of the non-linear Zener model are identified by the experimental equivalent stiffness and damping. The identified model correctly reproduces the frequency- and preload-dependent dynamic properties of the elastomeric material. The model is verified to be able to predict the dynamic behaviour of the elastomeric element through the comparison between the numerically simulated and the experimentally measured reaction force to a given deformation time history. Time domain simulations with the model of the reference ERS demonstrate that the modelled frequency- and preload-dependent stiffness and damping of the elastomeric material make a clear difference in the transient and steady-state response of the system when distant frequency contributions are involved.

Dynamic Characteristics of a Machine Tool at Working Positions in Operating Test

2011 ◽  
Author(s):  
Huimin Dong ◽  
Yang Tan ◽  
Delun Wang ◽  
Yali Ma
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Dynamic Properties ◽  
Vibration Energy ◽  
Testing Method ◽  
Spring Element ◽  
Machining Center ◽  
Brick Element ◽  
Stiffness And Damping

A machine tool is an assembly structure fitted by some moveable substructures, which the relative motion between the substructures creates normal and limit operating positions. Along with the substructures moving, the distributions of masses, stiffness and damping of the machine in space vary, leading to variety of structure distributions and dynamic properties. For exploring the dynamic properties distributions of machine tools, this paper presents a testing method under practical operational excitations, which is under operating excitations from remaining unbalanced value in the spindle, and collecting vibration signals of time and frequency at the spindle foreside at working positions. To identify resonance characteristics, a judging matrix is established by comparing vibration energy and vibration amplitude at 1st octave. By this method, MDH50 active pole horizontal machining center is tested, and the dynamic characteristics is determined. It reveals that dynamic characteristics of resonance come from the substructure independent resonance and their superposition in operating excitation. For verifying this result, FEA is conducted, in which 20 nodes brick element and spring element are applied to build the model entities and interfaces. The analysis result by FEM is consistent to the testing results. The research provides foundation for how setting up machining programs to avoid the resonance vibration of the machine in the operating.

Dynamic model for large multi-flexible-body space structures

2014 ◽  
Vol 14 (03) ◽  
pp. 1350072 ◽  
Author(s):  
D. X. Li ◽  
W. Liu ◽  
Y. J. Lei ◽  
X. Y. Sun
Keyword(s):  
Structural Model ◽  
Dynamic Properties ◽  
Structural Models ◽  
Space Structures ◽  
Flexible Body ◽  
Structural Dynamic ◽  
Solar Arrays ◽  
Set Up ◽  
Stiffness And Damping ◽  
Multi Body

Large multi-flexible-body space structures, such as space solar arrays, comprise of multiple flexible substructures that are connected by joint hinges. Unlike traditional continuous structural models, a noncontinuous multi-flexible-body structural model with joint hinges is set up for the multi-flexible-body structure herein. In contrast to the general multi-body structural models in which each substructure is taken as a rigid body, the elastic deformation of every substructure in the multi-flexible-body structural model is taken into account. Furthermore, the connection stiffness and friction damping of joint hinges are considered as they affect the structural dynamic properties. All of the aforementioned considerations make the dynamic modeling of this multi-flexible-body structural system rather difficult. To solve the problem, an innovative semi-analytical model is developed for each flexible substructure. A four-node massless spring-damper element is built up for each joint hinge, in which the stiffness and damping coefficients of the hinge are calibrated by experiments. By comparing the computed results with experimental results, it can be concluded that the method proposed herein is correct and efficient.

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