scholarly journals Study on the dynamic identification method of the weak part of the bar-shaped combined structure

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199652
Author(s):  
Tieneng Guo ◽  
Lingjun Meng ◽  
Jinxuan Cao ◽  
Chunsheng Bai ◽  
Xu Hua ◽  
...  
Keyword(s):  
Machine Tool ◽  
Test Method ◽  
Fe Method ◽  
Dynamic Identification ◽  
Vibration Data ◽  
Weak Part ◽  
Combined Structure ◽  
Type Machine ◽  
Value Decomposition ◽  
Space Method

The weak part of the stiffness of machine tool combined structure is the key to improve the stiffness of machine tool. To overcome the static deformation with difficulty acquisition, the paper chooses machine tool combined structure which can be equivalent to one-dimensional bar structure, and a weakness index (WI) is proposed to identify the weak part of the stiffness by means of the dynamic hammer test method. Based on the bar structure as a numerical example, the weak parts are modeled as EA reduction in stiffness while the mass is maintained at a constant value. Thorough finite element (FE) method simulations are performed to assess the robustness and limitations of the method in several scenarios with single and multiple weakness. On the crossbeam of gantry type machine tool, the sensors are used to collect vibration data, the structural modal parameters are obtained by singular value decomposition (SVD) technique, and the dynamic characteristics are systematically reconstructed by using modal state space method to obtain stiffness data at zero-frequency. Then, the weak part of the structural stiffness is identified by the weakness index. Finally, the comparison of FE simulations and experiment results are provided to illustrate the working of the method.

An approach to identify the weak parts of stiffness for the machine tool cantilever structure

2021 ◽  
pp. 095440622199871
Author(s):  
Tieneng Guo ◽  
Lingjun Meng ◽  
Jinxuan Cao ◽  
Chunsheng Bai
Keyword(s):  
Machine Tool ◽  
Elastic Support ◽  
Structural Stiffness ◽  
Vibration Data ◽  
Stiffness Reduction ◽  
Fe Simulations ◽  
Cantilever Structure ◽  
Combined Structure ◽  
Space Method ◽  
Zero Frequency

Investigating weak parts of the structure is one of the most important issues for improving the stiffness of the machine tool. However, studies show that overcoming the static deformation is a challenging problem in practical structures. In the present study, the dynamic hammer testing approach is applied to analyze the cantilever structure of the machine tool with elastic support. Accordingly, a new weakness index (WI) is proposed to identify weak parts of the cantilever structure with an elastic support. Then the cantilever beam with the elastic support is numerically simulated and weak parts are modeled as stiffness reduction. In this regard, finite element (FE) simulations are carried out to evaluate the effectiveness of the WI method in several scenarios with single and multiple weaknesses, including the noise case. In the combined structure of the tailstock and the bed of the machine tool, sensors are utilized to collect vibration data. Furthermore, the dynamic characteristics are calculated through the modal state-space method to obtain the stiffness data at zero-frequency. Then, weak parts of the structural stiffness are identified based on the weakness index. It is found that the FE simulations are in an excellent agreement with the experiment. Therefore, it is proved that the WI can accurately identify the weak parts of the machine tool cantilever structure.

scholarly journals Research on the dynamic identification method of weak parts in cantilever structures

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110169
Author(s):  
Tieneng Guo ◽  
Lingjun Meng ◽  
Xu Hua ◽  
Cheng Zhou ◽  
Liwei Peng
Keyword(s):  
Machine Tool ◽  
Complex Problem ◽  
Static Deformation ◽  
Machining Accuracy ◽  
Test Machine ◽  
Dynamic Identification ◽  
Stiffness Reduction ◽  
Weak Part ◽  
Cantilever Structure ◽  
System Reconstruction

Determining the weak parts of a structure is one of the key issues in the field of machine tool stiffness improvement. However, studies show that overcoming the static deformation with acquisition difficulty is a complex problem in practical structures. This study considers the machine tool cantilever structure, as a cantilever beam and bar structure, where the objective is to propose a weakness index, to identify the weak part, using system reconstruction to extract the measured static deformation data and the fitting data. Stiffness reduction is used to simulate weak parts, while the effectiveness of the method is evaluated, in the case of various weakness values and of different noise levels, using the finite element simulation approach. The validity of the proposed method is illustrated through comparison of the theoretical results to the experimental ones, using the cantilever structure of a test machine tool. The research content provides some means of improving the machining accuracy of machine tools.

scholarly journals Autonomous Identification and Positioning of Trucks during Collaborative Forage Harvesting

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1166
Author(s):  
Wei Zhang ◽  
Liang Gong ◽  
Suyue Chen ◽  
Wenjie Wang ◽  
Zhonghua Miao ◽  
...  
Keyword(s):  
Field Experiments ◽  
Absolute Error ◽  
Identification Accuracy ◽  
Depth Image ◽  
Dynamic Identification ◽  
Random Sample Consensus ◽  
Harvesting Efficiency ◽  
Value Decomposition ◽  
Forage Harvester ◽  
Ransac Algorithm

In the process of collaborative operation, the unloading automation of the forage harvester is of great significance to improve harvesting efficiency and reduce labor intensity. However, non-standard transport trucks and unstructured field environments make it extremely difficult to identify and properly position loading containers. In this paper, a global model with three coordinate systems is established to describe a collaborative harvesting system. Then, a method based on depth perception is proposed to dynamically identify and position the truck container, including data preprocessing, point cloud pose transformation based on the singular value decomposition (SVD) algorithm, segmentation and projection of the upper edge, edge lines extraction and corner points positioning based on the Random Sample Consensus (RANSAC) algorithm, and fusion and visualization of results on the depth image. Finally, the effectiveness of the proposed method has been verified by field experiments with different trucks. The results demonstrated that the identification accuracy of the container region is about 90%, and the absolute error of center point positioning is less than 100 mm. The proposed method is robust to containers with different appearances and provided a methodological reference for dynamic identification and positioning of containers in forage harvesting.

scholarly journals A Non-Delay Error Compensation Method for Dual-Driving Gantry-Type Machine Tool

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 748
Author(s):  
Qi Liu ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
Yu Qiao ◽  
Qian Cheng ◽  
...  
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Prediction Method ◽  
Compensation Method ◽  
Industrial Robots ◽  
Numerical Control ◽  
Heavy Duty ◽  
Positioning Errors ◽  
Compensation Methods ◽  
Type Machine

The drive at the center of gravity (DCG) principle has been adopted in computer numerical control (CNC) machines and industrial robots that require heavy-duty and quick feeds. Using this principle requires accurate corrections of positioning errors. Conventional error compensation methods may cause vibrations and unstable control performances due to the delay between compensation and motor motion. This paper proposes a new method to reduce the positioning errors of the dual-driving gantry-type machine tool (DDGTMT), namely, a typical DCG-principle-based machine tool. An error prediction method is proposed to characterize errors online. An algorithm is proposed to quickly and accurately compensate the errors of the DDGTMT. Experiment results verify that the non-delay error compensation method proposed in this paper can effectively improve the accuracy of the DDGTMT.

Control of PLC for Paving Stock Mechanism of New-Type Machine Tool about Rapid Prototyping Manufacturing for Ceramic Parts

2010 ◽  
Vol 154-155 ◽  
pp. 1085-1090
Author(s):  
Dong Qiang Gao ◽  
Zhen Ya Tian ◽  
Fei Zhang
Keyword(s):  
Rapid Prototyping ◽  
Machine Tool ◽  
Machine Tools ◽  
Programmable Logic Controller ◽  
Programmable Logic ◽  
New Type ◽  
Type Machine ◽  
Working Principle ◽  
Rapid Prototyping Manufacturing ◽  
Automatic Manufacturing

With the development of the rapid prototyping manufacturing for ceramic parts, it is possible to shorten the manufacturing period of ceramic parts and improve the enterprise’s productivity efficiency. The development situation of the machine tools about rapid prototyping manufacturing for ceramic parts was introduced. A new-style device about rapid prototyping manufacturing for ceramic parts, which is based on the technology of laminated coalition and rapid concrete prototyping for ceramic parts, is designed. The basic constitutions, technical processing and working principle of the paving stock mechanism of the device have also been described. The PLC (programmable logic controller) is applied in the paving stock mechanism for controlling and runs well, which meets the requirements of automatic manufacturing for ceramic parts and improves the efficiency.

An investigation on modeling and compensation of synthetic geometric errors on large machine tools based on moving least squares method

2016 ◽  
Vol 232 (3) ◽  
pp. 412-427 ◽  
Author(s):  
Zihan Li ◽  
Wenlong Feng ◽  
Jianguo Yang ◽  
Yiqiao Huang
Keyword(s):  
Machine Tool ◽  
Least Squares ◽  
Error Compensation ◽  
Machine Tools ◽  
Geometric Error ◽  
Moving Least Squares ◽  
Geometric Errors ◽  
Position Accuracy ◽  
Type Machine ◽  
Large Machine

This article intends to provide an efficient modeling and compensation method for the synthetic geometric errors of large machine tools. Analytical and experimental examinations were carried out on a large gantry-type machine tool to study the spatial geometric error distribution within the machine workspace. The result shows that the position accuracy of the tool-tip is affected by all the translational axes synchronously, and the position error curve shape is non-linear and irregular. Moreover, the angular error combined with Abbe’s offset during the motion of a translational axis would cause Abbe’s error and generate significant influence on the spatial positioning accuracy. In order to identify the combined effect of the individual error component on the tool-tip position accuracy, a synthetic geometric error model is established for the gantry-type machine tool. Also, an automatic modeling algorithm is proposed to approximate the geometric error parameters based on moving least squares in combination with Chebyshev polynomials, and it could approximate the irregular geometric error curves with high-order continuity and consistency with a low-order basis function. Then, to implement real-time error compensation on large machine tools, an intelligent compensation system is developed based on the fast Ethernet data interaction technique and external machine origin shift, and experiment validations on the gantry-type machine tool showed that the position accuracy could be improved by 90% and the machining precision could be improved by 85% after error compensation.

Satellite Fault Detection and Isolation through Decoupling Parity Space

2011 ◽  
Vol 110-116 ◽  
pp. 4406-4414
Author(s):  
Zheng Wang ◽  
Yan Jun Li ◽  
Xiao Wei Sun
Keyword(s):  
Singular Value Decomposition ◽  
Singular Value ◽  
Fault Detection And Isolation ◽  
Actuator Fault ◽  
Actuator Faults ◽  
Eigen Value ◽  
Parity Space ◽  
Simulation Results ◽  
Value Decomposition ◽  
Space Method

In order to detect and isolate orbiting satellite actuator faults, a decoupling parity space method was extended. The decoupling parity vector was obtained using this method by singular value decomposition. Sometimes this vector may not exist, then by singular value substitution or generalized Eigen value method was used for solving the optimal approximation. The vector can easily make satellite actuator fault detected and isolated. The simulation results showed the effectiveness of the proposed algorithm.

Research on Cutting Stability of High-Efficiency Micro Turn-Milling Compound Machine Tool Based on Lobes

2019 ◽  
Vol 295 ◽  
pp. 59-65
Author(s):  
Zhong Peng Zheng ◽  
Xin Jin ◽  
Ye Wang Sun ◽  
Xin Yang Jiang ◽  
Zhi Jing Zhang ◽  
...  
Keyword(s):  
Machine Tool ◽  
High Efficiency ◽  
Cutting Parameters ◽  
Milling Process ◽  
Test Method ◽  
Cutting Process ◽  
Milling Machine ◽  
Cutting Stability ◽  
Milling Chatter ◽  
Turn Milling

In order to improve the cutting stability of high-efficiency micro turn-milling machine tools, avoid the chattering problem during the cutting process. In this paper, the chatter problem in the cutting process is studied based on the stable lobes. By analyzing the high-efficiency turn-milling machine tool mechanism and the turn-milling model, the micro turn-milling dynamic dynamic vibration model and the mathematical model of turn-milling chatter are obtained. Then, based on the hammer test method, the transfer function of the tool-workpiece system is obtained, and the turn-milling stable lobes of the high-efficiency micro turn-milling machine tool is constructed. Finally, the research on the stable zone of the turning main spindle parts, the turning back spindle parts and the high-frequency milling part are completed. The experimental research results guide and optimize the selection of cutting parameters for turn-milling process.

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