Study on Fault Diagnosis and Repair Strategy of CNC Machine Tool

2013 ◽  
Vol 791-793 ◽  
pp. 967-970
Author(s):  
Guo Min Lin ◽  
Miao Shang ◽  
Wen Guang Zhang

CNC machine tool fault types, repair characteristics, the principle to be followed are described. The mechanical systems, Numerical control system, servo system fault diagnosis and repair for CNC machine tools are analyzed in detail. The strategy of the hardware faults such as main spindle part, the ball screw-nut pairs, cutter and tool change device, the strategy of the software repair are proposed.

2010 ◽  
Vol 97-101 ◽  
pp. 2914-2920 ◽  
Author(s):  
Qin Wu ◽  
Zhi Yuan Rui ◽  
Jian Jun Yang

The computer numerical control (CNC) machine tool was investigated and the dynamics model for the servo feed system was established. Based on the fixing constraint of the ball screw, the mathematical models of axial stiffness and torsion stiffness are constructed. According to the effects of stiffness on the dynamic performance, the simulation model for CNC machine tool feed system with stiffness considered was set up by the dynamic simulation tool Simulink, and a curve representing the performance of the system was obtained. To reduce the effect of stiffness on the system, the feedforward control strategy is used for stiffness compensation. The simulation results show that the stability and response performances of the system are improved and the steady-state error of the system is reduced by the control strategy.


2021 ◽  
Vol 11 (24) ◽  
pp. 11770
Author(s):  
Tao Sun ◽  
Wen Wang ◽  
Zhanfeng Chen ◽  
Yewen Zhu ◽  
Kaifei Xu ◽  
...  

Due to the errors of the servo system and the errors of the ball screw drive system, the positioning errors inevitably occur in the process of CNC machine tools. The measurement of traditional equipment is limited by a fixed measurement radius and a single degree of freedom, which can only be measured within a fixed plane. In this paper, four different positioning errors of CNC machine tools are first measured at full scale by using J-DBB (a modified double ball bar with one spherical joint connecting two bars) method. The J-DBB device uses a three-degree-of-freedom spherical joint as a connecting part, which realizes that the measurement radius can be continuously changed, and the measurement space is a spatial sphere. First, the principle of the J-DBB method is briefly introduced. Next, four typical positioning errors of CNC machine tools are analyzed and examined, which contain the uniform contraction error of ball screw and linear grating, periodic error of the ball screw and linear grating, interference of measurement devices error, and opposite clearance error. In the end, the trajectories of the CNC machine tool spindle with a single positioning error are simulated by using the J-DBB method. The results reveal that this method can be used for the positioning error of machine tools, which helps to better understand the spatial distribution of CNC machine tool errors and provides guidance for the reasonable selection of working areas to improve the machining accuracy of parts.


2013 ◽  
Vol 584 ◽  
pp. 208-213 ◽  
Author(s):  
Zhe Liu ◽  
Jing Chuan Dong ◽  
Tai Yong Wang ◽  
Bo Li ◽  
Yu Long Cui

From the middle of the 20th century, CNC(Computer numerical control) machine tool has brought a revolutionary change to the mechanical manufacturing industry. CNC machine tool is a kind of highly mechatronics product. It has the Characteristic of high precision and high productivity. Therefore it develops quite fast and improves various kind of the quality of the products. It speeds up the development of machinery industry. In order to meet the requirements of the processing accuracy and speed of modern society, the structure and components of the machine have also become complicated. In order to protect the safety of operators and reduce time of machine repaired as well as improve efficiency, the requirements of the reliability of CNC machine tool should be greatly improved. This study will briefly introduce the concept of reliability and put forward some measures to improve the reliability.


2010 ◽  
Vol 42 ◽  
pp. 335-338
Author(s):  
Hua Li Su ◽  
Xiao Peng Miao ◽  
Yong Zhang

With the continuous development of CNC technology, CNC machine tools run at the higher speed. Cutting force will be greater, which is bound to exacerbate the wear and tear of the machine tool guides. Therefore, new requirements of numerical control machine tool guide surface hardness are proposed. Using Laser surface heat treatment process to scan the guide surface of CNC Machine Tool, the guide can get high hardness hardened layer. After being casted iron HT300 was heat treated by the laser, the microstructure is homogeneous, very fine martensite. Its Surface hardness can get to HV832. The treatment enhances the surface abrasion resistance, scratch-resistant capacity.


2015 ◽  
Vol 4 (2) ◽  
pp. 28-46 ◽  
Author(s):  
Anoop Kumar Sahu ◽  
Nitin Kumar Sahu ◽  
Atul Kumar Sahu

In today's era, managerial decision making has become a very momentous component due to the leverage of attention on achieving organizational goal i.e. enhancing effective utilization of input assets, satisfying customers' demand and minimizing loss (maximize profit). The evaluation of the most appropriate Computer Numerical Control (CNC) machine tool has become one of the key factors for sustaining the organization/manufacturing sectors/production units at competitive global market place. Productivity, precision and accuracy etc. are the most important issues behind adaptation/exploration of CNC machine tools. So, in such a cases, subjective indices are considered beside the objective indices and complexity of the CNC machine tool evaluation decision problems is solved via subjective assessments (judgment) of expert panel, also called the decision-making group. In this reporting, TOPSIS (technique for order preference by similarity to ideal solution) based Multi-Criteria Decision Making (MCDM) approach has fruitfully applied to emphasize the decision making scenario at the subjective information evaluation index (indices) platform. So, TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) analytical methodology conjunction with Trapezoidal Fuzzy Number (TFN) has been explored for assessing and benchmarking the most preferable CNC machine tool from a group of preferred options/alternatives. Finally, an empirical case study has been carried out check the feasibility, efficiency and validity of proposed methodology and the benchmarking of preferred alternative machine tool has been derived in accordance with descending value of the ‘collective index'. Higher value of ‘collective index' reflects higher degree of performance extent.


Author(s):  
Y Q Zhou ◽  
X S Mei ◽  
G D Jiang ◽  
N G Sun ◽  
T Tao

Slide level has a lot of influence on computer numerical control (CNC) machine tool performance. The deterioration of slide level will result in torsional vibration of the feed-axis control system and lower CNC machine tool control precision. Hence, it is necessary to investigate evaluation technology for the slide level of CNC machine tools. In this article, a novel kind of sensorless evaluation method for machine tool slide level based on linear scale or motor encoder and AC servo motor current/output torque is proposed. To improve evaluation precision, a kind of filtering method based on empirical mode decomposition (EMD) technology is employed. The analysis results of the experiments show that it is simple, rapid, feasible, and reliable to use sensorless information for evaluating slide level based on the EMD method.


2021 ◽  
Author(s):  
Mohmad Iqbal ◽  
Ashok Kumar Madan

Abstract The efficiency of the Flexible Manufacturing System (FMS) is highly influenced by computer numerical control (CNC) machine tools. The most common causes of CNC machine tool failure is the bearing faults that influences the performance of manufacturing system. The detection and diagnosis of bearing defects are crucial to the reliable functioning of revolving machinery. This paper suggests an intelligent vibration-based condition and fault diagnostic technique for the identification of bearing faults in CNC machine tool. Investigational vibration data obtained for various bearings and operational requirements were analyzed in order to create a structure for the monitoring and classification of bearing defects in order to determine the health of the machine. Fault diagnosis was made using hybrid signal decomposition (HSD) methodology for the decomposition of the vibration signal. Vibration features derived from the received decomposed raw signal were chosen using the key component review to eliminate redundant features. Subsequently, these related features were input into support vector machines (SVM) and artificial neural network (ANN) for classification of various bearing faults in CNC machine tool. Experimental outcome suggest that the proposed approach has an immense capacity to prevent unplanned and unnecessary device shutdowns due to loss of bearings in CNC machine tool.


2010 ◽  
Vol 455 ◽  
pp. 621-624
Author(s):  
X. Li ◽  
Y.Y. Yu

Because of the practical requirement of real-time collection and analysis of CNC machine tool processing status information, we discuss the necessity and feasibility of applying ubiquitous sensor network(USN) in CNC machine tools by analyzing the characteristics of ubiquitous sensor network and the development trend of CNC machine tools, and application of machine tool thermal error compensation based on USN is presented.


2014 ◽  
Vol 945-949 ◽  
pp. 1707-1712
Author(s):  
Bin Shen ◽  
Shu Yu Zhao ◽  
Jia Hai Wang ◽  
Juergen Fleischer

Based on the authors previous work of developing an expert system for fault diagnosis of CNC machine tool, this paper studied the theory and method of CNC remote fault diagnosis expert system based on B/S, and presents schema and structure of the expert system in detailed. Case based reasoning is used for the multi-alarm diagnosis, and rule based reasoning is used for single-alarm diagnosis. At last fault diagnosis expert system was designed and developed making use of C# and ASP.NET.


Symmetry ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 686 ◽  
Author(s):  
Meng Duan ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
Yongquan Zhang ◽  
Zhangjie Li ◽  
...  

It is of great significance to study the dynamic characteristics of twin ball screw (TBS) feed system to improve the precision of gantry-type dual-driven computer numerical control (CNC) machine tools. In this paper, an equivalent dynamic model of the TBS feed system is established utilizing lumped mass method considering the stiffness of joints. Equivalent axial stiffness of screw-nut joints and bearing joints are both calculated by Hertz contact theory. Furthermore, a friction model is proposed because the friction force of the screw nut affects the stiffness of the joints. Then, the friction parameters are obtained by using the nonlinear system identification method. Meanwhile, a finite element model (FEM) is developed to assess the dynamic characteristics of TBS feed system under the stiffness of joints. Finally, validation experiments are conducted, and the results show that the positions of the nut and the velocities of worktable greatly affect the dynamic characteristics of the TBS feed system. Compared with the theoretical calculation, FEM and experiments indicate that the dynamic modeling proposed in this article can reach a higher accuracy.


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