Reliability Analysis and Improvement of ATCs of CNC Lathes

2010 ◽  
Vol 37-38 ◽  
pp. 939-943 ◽  
Author(s):  
Yi Qiang Wang ◽  
Xiao Jun Wang ◽  
Shun Ming Hua
Keyword(s):  
Failure Analysis ◽  
Block Diagram ◽  
Numerical Control ◽  
Coding System ◽  
Failure Data ◽  
Cnc Lathe ◽  
Automatic Tool Changer ◽  
Automatic Tool ◽  
Set Up ◽  
Field Failure

An automatic tool changer (ATC) is one of the most important subsystems of a computerized numerical control (CNC) lathe. The field failure analysis is very important to improve the reliability of the ATC. The structure and mechanism of an ATC is briefly introduced. Its brief reliability block diagram is set up. With this understanding, through the collection of the field failure data, a coding system to code failure data is devised and a failure analysis database of CNC lathes is accrued. The failure mode and cause are analyzed to indicate the weak subsystem of the ATC. Some suggestions on improving the reliability have been proposed.

Application of Tree Graph Method for Reducing the Total Time of Tool Changing in Milling and Boring Machine Tools

2013 ◽  
Vol 371 ◽  
pp. 431-435 ◽  
Author(s):  
Claudiu Obreja ◽  
Gheorghe Stan ◽  
Lucian Adrian Mihaila ◽  
Marius Pascu
Keyword(s):  
Machine Tools ◽  
Design Method ◽  
Machining Process ◽  
Cnc Machine Tools ◽  
Tree Graph ◽  
Cnc Machine ◽  
High Productivity ◽  
Automatic Tool Changer ◽  
Automatic Tool ◽  
Set Up

With a view of increasing the productivity on CNC machine tools one of the main solution is to reduce, as much as possible, the auxiliary time consumed with the set-up and replacement of the tools and work pieces engaged in the machining process. Reducing the total time of the tool changing process by the automatic tool changer system can be also achieved through minimizing the number of movements needed for the actual exchange of the tool, from the tool magazine to the machine spindle (the optimization of the tool changing sequences). This paper presents a new design method based on the tree-graph theory. We consider an existing automatic tool changing system, mounted on the milling and boring machining centre, and by applying the new method we obtain all the possible configurations to minimize the tool changing sequence of the automatic tool changer system. By making use of the method proposed we obtain the tool changing sequences with minimum necessary movements needed to exchange the tool. Reconfiguring an existing machine tool provided with an automatic tool changer system by making use of the proposed method leads to obtaining the smallest changing time and thus high productivity.

Integrated reliability and maintainability analysis of Computerized Numerical Control Turning Center considering the effects of human and organizational factors

2019 ◽  
Vol 26 (1) ◽  
pp. 87-103
Author(s):  
Rajkumar Bhimgonda Patil
Keyword(s):  
Organizational Factors ◽  
Numerical Control ◽  
Content Type ◽  
Failure Data ◽  
Turning Center ◽  
Maintainability Analysis ◽  
Human And Organizational Factors ◽  
Mean Time ◽  
Best Fit ◽  
Field Failure

Purpose Reliability, maintainability and availability of modern complex engineered systems are significantly affected by four basic systems or elements: hardware, software, organizational and human. Computerized Numerical Control Turning Center (CNCTC) is one of the complex machine tools used in manufacturing industries. Several research studies have shown that the reliability and maintainability is greatly influenced by human and organizational factors (HOFs). The purpose of this paper is to identify critical HOFs and their effects on the reliability and maintainability of the CNCTC. Design/methodology/approach In this paper, 12 human performance influencing factors (PIFs) and 10 organizational factors (OFs) which affect the reliability and maintainability of the CNCTC are identified and prioritized according to their criticality. The opinions of experts in the fields are used for prioritizing, whereas the field failure and repair data are used for reliability and maintainability modeling. Findings Experience, training, and behavior are the three most critical human PIFs, and safety culture, problem solving resources, corrective action program and training program are the four most critical OFs which significantly affect the reliability and maintainability of the CNCTC. The reliability and maintainability analysis reveals that the Weibull is the best-fit distribution for time-between-failure data, whereas log-normal is the best-fit distribution for Time-To-Repair data. The failure rate of the CNCTC is nearly constant. Nearly 66 percent of the total failures and repairs are typically due to the hardware system. The percentage of failures and repairs influenced by HOFs is nearly only 16 percent; however, the failure and repair impact of HOFs is significant. The HOFs can increase the mean-time-to-repair and mean-time-between-failure of the CNCTC by nearly 65 and 33 percent, respectively. Originality/value The paper uses the field failure data and expert opinions for the analysis. The critical sub-systems of the CNCTC are identified using the judgment of the experts, and the trend of the results is verified with published results.

Braking Solution for a Hydraulically Driven Linear Pallet Changer Mechanism

2014 ◽  
Vol 657 ◽  
pp. 485-489
Author(s):  
Lucian Mihăilă ◽  
Gheorghe Stan
Keyword(s):  
Medium Size ◽  
Kinematic Parameters ◽  
Two Stage ◽  
High Productivity ◽  
Counter Pressure ◽  
Pressure Limitation ◽  
Automatic Tool Changer ◽  
Hydraulic Cylinders ◽  
Automatic Tool ◽  
Set Up

The use of machining centres is predominant in the case of small and medium size batch manufacturing, their advantages being materialised in high productivity. The productivity is owed, mainly, to the small auxiliary times consumed with the tool and material change, times which are served by the automatic tool changer system and the automatic pallet changer. The purpose of this article researches aims to determine the kinematic parameters of an hydraulically driven linear pallet changer in two cases (when the deceleration is carried out through a throttle and when the deceleration is made through a new solution). Thus, an experimental set-up, which matches an hydraulically driven linear pallet changer, was designed and built. The experiments aimed toward using a classic braking method of hydraulic cylinders and a new two-stage braking with counter-pressure limitation.

Influence of relative humidity and air temperature on the stopping position of the automatic tool changer in a CNC machine when using a pneumatic cylinder

2021 ◽  
pp. 2140013
Author(s):  
Hung Pham Van ◽  
Duong Nguyen Thuy
Keyword(s):  
Relative Humidity ◽  
Friction Force ◽  
Air Temperature ◽  
Numerical Control ◽  
Pneumatic Cylinder ◽  
Cnc Milling ◽  
Cnc Machine ◽  
Cnc Milling Machine ◽  
Automatic Tool Changer ◽  
Automatic Tool

The automatic tool changer (ATC) in computerized numerical control (CNC) milling machine often uses pneumatic dynamic sources. Friction in the pneumatic cylinder affects the ATC’s stopping position; this friction depends on many factors, including the air environment’s relative humidity and temperature. This paper presents the results of research on the effects of relative humidity (RH) and air temperature (T) on the stopping position of an ATC using a pneumatic cylinder. Studies were conducted at temperatures of [Formula: see text]C, [Formula: see text]C and [Formula: see text]C and relative humidity values of 51%, 75% and 99% for different speeds of the pneumatic cylinder (30, 50 and 100 mm/s). The results show that when the humidity increases from 51% to 99% and the temperature increases from [Formula: see text]C to [Formula: see text]C, the friction force decreases. The friction force is related to the relative humidity and temperature of the air. Thus, the deviation of the ATC’s stopping position depends on the relative humidity and temperature of the area under investigation.

Track-based analysis for profile generation on globoidal cam in automatic tool changer of CNC machining center

2019 ◽  
Vol 39 (2) ◽  
pp. 369-379 ◽  
Author(s):  
Kuldeep Verma ◽  
R.M. Belokar ◽  
Vinod Kumar Verma ◽  
Klimis Ntalianis
Keyword(s):  
Practical Implication ◽  
Cnc Machining ◽  
Numerical Control ◽  
Practical Implementation ◽  
Cnc Machines ◽  
Content Type ◽  
Automatic Tool Changer ◽  
Cam Profile ◽  
Measuring Machine ◽  
Automatic Tool

PurposeThis paper aims to propose an elementary approach towards the measurement of a globoidal cam profile used in an automatic tool changer (ATC) of computer numerical control (CNC) machines.Design/methodology/approachA simple and unique online method has been designed for the profile metrology of the cam. This simple methodology will replace the traditional methodology of profile metrology of cam by coordinate measuring machine (CMM). A globoidal cam with an indexable turret and roller follower (rotating in an enclosed track) has been evaluated in our analysis. This analysis plays a significant role in the performance determination of the cam as well as the ATC of CNC machines.FindingsA novel model has been designed and implemented to investigate the profile of a globoidal cam. The proposed methodology becomes an enhancement over the old methodology, i.e. measurement through CMM. Theoretical analysis and practical implementation prove the significance of the method.Originality/valueAn enhanced methodology to effectively measure the globoidal cam profile has been proposed. The practical implication of the proposed methodology remains for the CNC machine tool and ATC manufacturers. Finally, analytical explorations have been carried out to prove the validity of the proposal.

A Note on the Early Failure Period for CNC Machining Tools

2012 ◽  
Vol 605-607 ◽  
pp. 734-738
Author(s):  
Zhi Cheng Jia ◽  
Zhao Jun Yang
Keyword(s):  
Cnc Machining ◽  
Distribution Model ◽  
Early Failure ◽  
Reliability Level ◽  
Failure Data ◽  
Tracing Test ◽  
Automatic Tool Changer ◽  
Main Fault ◽  
Automatic Tool ◽  
Fault Mode

Through the plentiful authentic early failure data collected by field tracing test of 30 CNC machining tools with ATC (Automatic Tool Changer), we searched for the rules and distribution of early failure of the CNC machining tools. Main fault mode and facts which usually make a great possible impact on the reliability of these products are identified based on an analysis of these early failure data. The distribution model of early failure is found by analyzing and processing these data with the method of regression analysis and hypothesis testing as well as Bayesian forecasting of early fault phenomena. Suggestions how to enhance reliability level of these products are proposed.

Early Failure Mode Effect and Criticality Analysis for CNC Machining Tools

2013 ◽  
Vol 303-306 ◽  
pp. 1653-1656 ◽  
Author(s):  
Zhi Cheng Jia ◽  
Zhao Jun Yang ◽  
Gui Xiang Shen
Keyword(s):  
Cnc Machining ◽  
Weak Links ◽  
Early Failure ◽  
Failure Data ◽  
Mode Effect ◽  
Automatic Tool Changer ◽  
Main Fault ◽  
Automatic Tool ◽  
Fault Mode ◽  
Criticality Analysis

According to the plentiful early failure data collected on the spots of 30 CNC machining tools with ATC (Automatic Tool Changer), FMECA method is used to analyze the main fault mode and facts which usually make a great possible impact on the reliability of these products during early failure period.We find out the fault positions and the ratios of the fault modes and fault causes. We further analyze the fault modes and fault causes which frequently arise in the subsystems and parts. Through the analyses of FMECA, we learn the weak links of CNC machining tools and provide bases for removing the products faults. Suggestions how to enhance reliability level of these products are proposed.

Fault Detection System and Reliability Analysis for Chain-Type Tool Magazine

2012 ◽  
Vol 542-543 ◽  
pp. 941-944
Author(s):  
Ye Hu ◽  
Zhao Jun Yang ◽  
Xiao Ming Zeng ◽  
Peng Fei Song ◽  
Yu Peng Ma ◽  
...  
Keyword(s):  
Fault Detection ◽  
Reliability Analysis ◽  
Large Scale ◽  
Detection System ◽  
Tool Magazine ◽  
Failure Data ◽  
Automatic Tool Changer ◽  
Automatic Tool ◽  
A Chain ◽  
Chain Type

By analyzing the structure features and tool changing process of a large-scale national Automatic Tool Changer (ATC) with a chain-type tool magazine, a chain-type tool magazine reliability test bench is designed with a new fault detection system, where a new failure data collecting method is applied for taking failure data statistics and reliability analysis. This set of fault detecting and reliability analyzing system not only provides a way for ATC to predict system faults, but also creates good conditions for further ATC reliability research.

Reliability Evaluation of Chain-Type Tool Magazine and ATC

2012 ◽  
Vol 271-272 ◽  
pp. 461-465 ◽  
Author(s):  
Xiao Hong Lu ◽  
Peng Zhuo Han ◽  
Wen Yi Wu
Keyword(s):  
Reliability Evaluation ◽  
Evaluation Index ◽  
Tool Magazine ◽  
Failure Data ◽  
Machining Center ◽  
Automatic Tool Changer ◽  
The Mean ◽  
Automatic Tool ◽  
Mean Time ◽  
Chain Type

As the tool magazine and automatic tool changer (ATC) are the important function units to reserve and change tools for the machining center, the tool-changing rate affects their reliability life which directly influences the performance level of the machining center. However, the reliability of the tool magazine and ATC has not yet got a reasonable evaluation index. Directing at the features of the tool magazine and ATC system, the mean tool change numbers between failures evaluation index is proposed, which is used to calculate the mean time to repair and estimate the collected failure data of the chain-type tool magazine and ATC. It can be seen that the tool magazine with continuous tool-changing adopts the mean tool change numbers between failures as the reliability evaluation index.

Reliability Evaluation of Circular Tool Magazine and Automatic Tool Changer

2012 ◽  
Vol 630 ◽  
pp. 245-248 ◽  
Author(s):  
Xiao Hong Lu ◽  
Peng Zhuo Han ◽  
Wen Yi Wu ◽  
Wei Jie
Keyword(s):  
Reliability Evaluation ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Mean Time Between Failures ◽  
Tool Magazine ◽  
Failure Data ◽  
Automatic Tool Changer ◽  
Automatic Tool ◽  
Availability Index ◽  
Mean Time

Tool magazine and automatic tool changer is important parts to fulfill the machining center tool reserve and automatic changing of the spindle tool. The reliability of them directly affects the performance of the host. But recently there are no researches on the reliability evaluation methods, so considering this situation, the reliability evaluation researches on CNC machine tools and their main parts at home and abroad are analyzed and concluded. Combining the collected failure data of the circular tool magazine and automatic tool changer, use MTBF (Mean Time between Failures), MTTR (Mean Time To Repair) and the inherent availability index to realize the reliability evaluation of the circular tool magazine and automatic tool changer. Thus put forward a method to study the reliability evaluation of circular tool magazine and automatic tool changer.

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