Effect of guide rail profile errors on the motion accuracy for a heavy-duty hydrostatic turntable

2019 ◽  
Vol 233 (15) ◽  
pp. 5350-5362 ◽  
Author(s):  
Yongsheng Zhao ◽  
Hongchao Wu ◽  
Congbin Yang ◽  
Ligang Cai ◽  
Zhifeng Liu
Keyword(s):  
Machine Tool ◽  
Reynolds Equation ◽  
Machining Accuracy ◽  
Guide Rail ◽  
Heavy Duty ◽  
Motion Equations ◽  
Rotating Speed ◽  
Proposed Model ◽  
Reaction Forces ◽  
Profile Errors

The motion accuracy of hydrostatic turntable is the key in improving the machining accuracy of heavy-duty machine tool. However, the motion accuracy of hydrostatic turntable depends not only on the offset load but also on the rotating speed of the turntable as well as the profile errors of the guide rails. In this paper, a simulation model is developed to analyze the effect of guide rail profile errors on the motion accuracy of hydrostatic turntable. The reaction forces of preload thrust bearing and hydrostatic circular oil pads are obtained based on the Reynolds equation of the lubricant film. The motion equations of hydrostatic turntable are derived in which the profile errors of two guide rails are considered. The results show that the motion accuracy of hydrostatic turntable can be affected by wavelength, amplitude of profile errors and speed, and offset load of turntable. Finally, the motion accuracy of heavy-duty hydrostatic turntable used in XCKA28105 type turning and milling composite machine tool is obtained by using the presented method. Comparing with the experimental results, the proposed model can be used to predict the machining accuracy caused by the profile errors of guide rails for any heavy-duty hydrostatic turntable.

A Novel Error Equivalence Model on the Kinematic Error of the Linear Axis of High-End Machine Tool

2021 ◽  
Author(s):  
Xinxin LI ◽  
Zhi-Min Li ◽  
Sun Jin ◽  
Jichang Zhang ◽  
Siyi Ding ◽  
...  
Keyword(s):  
Machine Tool ◽  
Elastic Deformation ◽  
Numerical Control ◽  
Small Displacement ◽  
Kinematic Error ◽  
Guide Rail ◽  
Linear Guide ◽  
Proposed Model ◽  
Equivalence Model ◽  
Kinematic Errors

Abstract The kinematic errors of the linear axis play a key role in machining precision of high-end CNC (Computer Numerical Control) machine tool. The quantification of error relationship is still an urgent problem to be solved in the assembly process of the linear axis, especially considering the effect of the elastic deformation of rollers. A systematic error equivalence model of slider is proposed to improve the prediction accuracy for kinematic errors of the linear axis which contains the base, the linear guide rail and carriage. Firstly, the geometric errors of assembly surface of linear guide rail are represented by small displacement torsor. According to the theory of different motion of robots, the error equivalence model of a single slider is established, namely the geometric error of assembly surface of linear guide rail and the pose error of slider is equivalent to the elastic deformation of roller. Based on the principle of vector summation, the kinematic error of a single slider is mapped to the carriage and the kinematic error of the linear axis is obtained. Besides, experiments validation of kinematic error model of the linear axis is carried out. It is indicated that the proposed model is accurate and feasible. The proposed model can provide an accurate guidance for the manufacturing and operation performance of the linear axis in quantification, and a more effective reference for the engineers at the design and assembly stage.

Characteristics evaluation of gas film in the aerostatic thrust bearing within rarefied effect

2016 ◽  
Vol 231 (2) ◽  
pp. 149-157 ◽  
Author(s):  
Dongju Chen ◽  
Shuai Zhou ◽  
Jihong Han ◽  
Jinwei Fan ◽  
Qiang Cheng
Keyword(s):  
Machine Tool ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Film Flow ◽  
Machining Accuracy ◽  
Aerostatic Bearing ◽  
Supply Pressure ◽  
Slip Regime ◽  
Key Factor ◽  
Gas Supply

The characteristic of gas film is a key factor in the performance of the aerostatic bearing. Because the gas film flow is in the slip regime, influence of the rarefied effect is significant. The modified Reynolds equation suitable for compressible gas in the rarefied effect is deduced through introducing the flow factor in the rarefied effect to the Reynolds equation. Pressure distribution, capacity, and stiffness of the gas film under the rarefied effect are analyzed. With the increase of gas pressure, the gas film capacity and stiffness of bearing would also increase. However, the greater the gas supply pressure, the more intense the gas film vibration, so it was important to select a reasonable gas supply pressure for achieving the optimal gas film characteristic. Finally, the gas rarefied effect is verified by the experiment indirectly, which agreed well with the analytical results and provided a theoretical guidance for the machining accuracy of the machine tool.

Study on the Thermal Characteristics Simulation and Error Compensation of Long Rail of Heavy Numerically-Controlled Machine Tool

2014 ◽  
Vol 577 ◽  
pp. 187-191
Author(s):  
Ming Yue Xiao ◽  
Zhong Ping Hua ◽  
Shui Sheng Cheng
Keyword(s):  
Finite Element ◽  
Machine Tool ◽  
Error Compensation ◽  
Thermal Deformation ◽  
Thermal Characteristics ◽  
Machining Accuracy ◽  
Guide Rail ◽  
Ansys Software ◽  
Working Process ◽  
Main Factors

In the working process of numerically-controlled machine tool, the generation of heat by friction between the guide rail and the workbench will cause the thermal deformation under the high temperature, which impacts on the machining accuracy of machine tool. Through the finite element modeling for the guide rail of machine tool by the ANSYS software, the thermal characteristics is simulated in the process of guide rail, then the main factors of thermal deformation is analyzed, finally the corresponding measures focusing on the error compensation is proposed.

Error correction technique for numerical control machine tools based on the simplex method

2021 ◽  
pp. 095440542110281
Author(s):  
Hongwei Liu ◽  
Rui Yang ◽  
Pingjiang Wang ◽  
Jihong Chen ◽  
Hua Xiang
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Simplex Method ◽  
Tool Path ◽  
Repeated Measurements ◽  
Numerical Control ◽  
Machining Accuracy ◽  
Correction Technique ◽  
Fluctuation Range ◽  
Nc Machine

The objective of this research is to develop a novel correction mechanism to reduce the fluctuation range of tools in numerical control (NC) machining. Error compensation is an effective method to improve the machining accuracy of a machine tool. If the difference between two adjacent compensation data is too large, the fluctuation range of the tool will increase, which will seriously affect the surface quality of the machined parts in mechanical machining. The methodology used in compensation data processing is a simplex method of linear programming. This method reduces the fluctuation range of the tool and optimizes the tool path. The important aspect of software error compensation is to modify the initial compensation data by using an iterative method, and then the corrected tool path data are converted into actual compensated NC codes by using a postprocessor, which is implemented on the compensation module to ensure a smooth running path of the tool. The generated, calibrated, and amended NC codes were immediately fed to the machine tool controller. This technique was verified by using repeated measurements. The results of the experiments demonstrate efficient compensation and significant improvement in the machining accuracy of the NC machine tool.

scholarly journals Recurrent neural networks with long term temporal dependencies in machine tool wear diagnosis and prognosis

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Jianlei Zhang ◽  
Yukun Zeng ◽  
Binil Starly
Keyword(s):  
Neural Network ◽  
Tool Wear ◽  
Machine Tool ◽  
Recurrent Neural Network ◽  
Machine Tools ◽  
Prediction Performance ◽  
Sequential Data ◽  
Diagnosis And Prognosis ◽  
Proposed Model

AbstractData-driven approaches for machine tool wear diagnosis and prognosis are gaining attention in the past few years. The goal of our study is to advance the adaptability, flexibility, prediction performance, and prediction horizon for online monitoring and prediction. This paper proposes the use of a recent deep learning method, based on Gated Recurrent Neural Network architecture, including Long Short Term Memory (LSTM), which try to captures long-term dependencies than regular Recurrent Neural Network method for modeling sequential data, and also the mechanism to realize the online diagnosis and prognosis and remaining useful life (RUL) prediction with indirect measurement collected during the manufacturing process. Existing models are usually tool-specific and can hardly be generalized to other scenarios such as for different tools or operating environments. Different from current methods, the proposed model requires no prior knowledge about the system and thus can be generalized to different scenarios and machine tools. With inherent memory units, the proposed model can also capture long-term dependencies while learning from sequential data such as those collected by condition monitoring sensors, which means it can be accommodated to machine tools with varying life and increase the prediction performance. To prove the validity of the proposed approach, we conducted multiple experiments on a milling machine cutting tool and applied the model for online diagnosis and RUL prediction. Without loss of generality, we incorporate a system transition function and system observation function into the neural net and trained it with signal data from a minimally intrusive vibration sensor. The experiment results showed that our LSTM-based model achieved the best overall accuracy among other methods, with a minimal Mean Square Error (MSE) for tool wear prediction and RUL prediction respectively.

Dynamic Analysis and Experimental Research of Laser Cutting Machines

2014 ◽  
Vol 915-916 ◽  
pp. 31-34
Author(s):  
Qing Ping Zhang ◽  
Zheng Ru Wang ◽  
Yan Fang Wang
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Laser Cutting ◽  
Machining Accuracy ◽  
Dynamics Analysis ◽  
Theoretical Base ◽  
Test Results ◽  
Cutting Machine ◽  
Manufacturing Errors ◽  
Theoretical Results

Vibration is one of the most important problems in laser cutting machine tool, which causes the manufacturing errors, also influences the machining accuracy of the parts. Modal analysis can calculate vibration type of structures. The paper presents how to use the powerful FEA software ANSYS to do the modal analysis on laser cutting machine tool and also studies the undamped free vibration on laser cutting machine tool. Finally, the test results and theoretical results were compared to verify the rationality of the modal, these provide theoretical base and conditions for dynamics analysis and optimal design.

Sensitivity Analysis of Geometric Errors for Five-Axis CNC Machine Tool Based on Multi-Body System Theory

2012 ◽  
Vol 271-272 ◽  
pp. 493-497
Author(s):  
Wei Qing Wang ◽  
Huan Qin Wu
Keyword(s):  
System Theory ◽  
Sensitivity Analysis ◽  
Machine Tool ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Body System ◽  
Cnc Machine ◽  
Multi Body ◽  
Five Axis

Abstract: In order to determine that the effect of geometric error to the machining accuracy is an important premise for the error compensation, a sensitivity analysis method of geometric error is presented based on multi-body system theory in this paper. An accuracy model of five-axis machine tool is established based on multi-body system theory, and with 37 geometric errors obtained through experimental verification, key error sources affecting the machining accuracy are finally identified by sensitivity analysis. The analysis result shows that the presented method can identify the important geometric errors having large influence on volumetric error of machine tool and is of help to improve the accuracy of machine tool economically.

Mathematical Model for the Influence of Machine Tool Parts Deformation on Machining Accuracy

2014 ◽  
Vol 556-562 ◽  
pp. 1354-1357
Author(s):  
Li Gong Cui ◽  
Gui Qiang Liang ◽  
Fang Shao
Keyword(s):  
Mathematical Model ◽  
Mathematical Method ◽  
Machine Tool ◽  
Cutting Tool ◽  
Lower Surface ◽  
Design Stage ◽  
Machining Accuracy ◽  
Cutting Point ◽  
The Mathematical Model

This paper presents a mathematical method to analyze the influence of each machine tool part deformation on the machining accuracy. Taking a 3-axis machine tool as an example, this paper divides the machine tool into the cutting tool sub-system and workpiece sub-system. Taking the deformation of lower surface of the machine bed as the research target, the mathematical model of the deformation on the displacement of the cutting point was established. In order to distribute the stiffness of each part, the contribution degree of each part on the machining accuracy was analyzed. Using this mathematical model, the stiffness of each part can be distributed at the design stage of the machine tool, and the machining accuracy of the machine tool can be improved economically.

Application of Multifunctional Materials for Machine Tool Structures

2009 ◽  
Author(s):  
Francesco Aggogeri ◽  
Angelo Merlo ◽  
Marco Mazzola ◽  
Nicola Pellegrini
Keyword(s):  
Thermal Stability ◽  
Machine Tool ◽  
Metal Foam ◽  
Operating Time ◽  
Weight Ratio ◽  
Material Behavior ◽  
Time Range ◽  
Machining Accuracy ◽  
Machine Component ◽  
Latent Heat Storage

The competition on the international markets pushes manufacturers towards shorter design cycles and decreasing manufacturing times and costs for their products. This trend generates a demand for smart, flexible and faster machining systems, easy to set up and configure, which are able to drastically reduce machining time and improve the final accuracy. This paper rises from these considerations evaluating the possible application of multifunction materials in machine tool (MT) design and building. These solutions can provide a fundamental impact on functionality and reliability of a manufacturing system. In particular, use of innovative materials in today’s technology continues to grow steadily. Numerous reasons for this growth include light weight, superior insulating abilities, energy absorbing performance, excellent strength/weight ratio and low cost. This paper aims to investigate a possible application of multifunction materials in realisation of structure components for Machine Tools. There are many aspects that affect the machining accuracy and the cutting conditions of a high performance MT. The most important issues are related to the static, dynamic, mechatronic and thermal behavior of the machines. In particular, a strict requirement that a machine tool has to fulfill in order to drastically reduce operating time while improving the final accuracy is the thermal stability. This paper shows a complete study and testing validation on prototypes (plates and beam) based on sandwiches with core made of metal foam (open and closed cells) materials impregnated by a PCM (Phase Material Change) wax. Metal foams represent a class of materials with low density and novel physical, mechanical, thermal, electrical and acoustic proprieties. They offer potential for lightweight structures, for energy absorption and thermal management. PCMs are latent heat storage materials that absorb heat keeping constant the temperature of a machine component in a defined time range. The authors have designed, realized and tested the prototypes developing thermal trials, and then evaluating the comparison between experimental data and simulative analysis (FEM). The trials consisted to process the prototypes at a variation of temperature in order to assess the PCM proprieties to absorb heat and maintain thermal stability in a defined time range. The paper shows also a simulative study on PCM material behavior and their application in MT design supported by experimental trials and data analysis. The significant advantages and perspectives that can be obtained in applying of these MT structures complete the developed study.

Model Research on Special Metal Cutting NC Machine Tool

2007 ◽  
Vol 10-12 ◽  
pp. 806-811
Author(s):  
Tong Zhao ◽  
P.Q. Ye ◽  
H. Zhang ◽  
X.K. Wang
Keyword(s):  
Machine Tool ◽  
Metal Cutting ◽  
Relation Module ◽  
Nc Machine Tool ◽  
Model Research ◽  
Unit Model ◽  
Proposed Model ◽  
Control Research ◽  
Function Unit ◽  
Nc Machine

In this paper the model of special metal cutting NC machine Tool is presented, which consists of a base module, an overall control module, particular functional modules as well as a relation module. Each module involved in aforementioned model will be composed by software, hardware and mechanical parts, so as to combine the convergence of the ideas of modularization and mechanical-electrical integration into current understanding of special NC machine tool through the proposed model. Specially, the relation module is introduced to deal with the linking among all the other modules. The presented model aims to broaden the perspective of machine designers intending to increase the efficiency in machine design. By giving the so-called function unit model a novel modeling approach is delivered to carry out control research of special metal cutting NC machine, which is followed by the formalization description method presented as a possible abstraction methodology towards the efficient description and identification of special metal cutting NC machine tool.

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