Design and research of CNC lathe reliability data collection and database establishment Beijing University of Science and Technology Jia Zhixin Ai Dongmei Jilin Industrial University Jia Yayi Yi Shangfeng N lathe failure situation was tracked. The reliability data was collected and the numerical control lathe reliability database was preliminarily established.
1 Introduction CNC machine tools are the basic equipment of modern manufacturing technology. Its technical level is an important indicator to measure the level of industrial modernization in a country. The reliability of CNC machine tools is the key to machine quality. At present, the reliability level of domestic CNC machine tools is significantly lower than that of foreign countries, which seriously affects the competitiveness of domestic CNC machine tools. Improving the reliability of domestic CNC machine tools has become a top priority.
Reliability analysis is based on a large amount of on-site data. By systematically and purposefully collecting data from various stages of the product life cycle, it analyzes and finds weak links in product reliability, improves design, and improves product quality, so it is reliable. The collection and analysis of sexual data plays an important role in reliability engineering. However, this aspect is a weak link in domestic reliability research. During the period from July 1, 1996 to December 31, 1996, we collected the reliability data of 42 N lathes of the Changchun Gear Factory of the Steam Group, and initially established the reliability database of CNC lathes. Taking this as an example, the method of collecting the reliability data of CNC machine tools and the method of establishing the database are explained.
2 Reliability Test Protocol Determination Reliability test is the main method to obtain reliability data. It is the basis for reliability design and analysis. In the past 30 years, the reliability test method has made great progress. Reliability testing is time consuming and expensive.
For CNC lathes, the main consideration is the test site and the test sample.
According to the test site, the reliability test is divided into two types: field test and laboratory test. Due to the complicated structure and many uncertain factors in the use conditions, the CNC lathe can use the field test method to collect the real reliability. Data reliability issues are a key issue in field trials. A complete collection plan must be developed in advance, and the data should be processed afterwards to eliminate unreasonable factors.
The reliability test can be divided into two types according to the sample size: full test and sample test. For the batch products of CNC lathes, it is impossible to carry out the full test, and only the test method of sampling and timing censoring can be used. In order to make the collected data representative and facilitate data collection, when selecting test samples, as many sample CNC lathes as possible should be selected as sampling samples, and the selected equipment should be concentrated. Therefore, this paper selects the Changchun Gear Factory of the automobile group with large amount of CNC lathes and relatively concentrated equipment as the test base, and takes 42 N lathes as samples to conduct a half-year follow-up investigation.
3 The reliability data is collected according to the “Criteria for Reliability Evaluation of CNC Lathesâ€, that is, the failure criterion of standard JB/GQ390 CNC lathe is: (1) Due to the quality defects of CNC lathe, the regulations cannot be completed under the specified conditions and within the specified time. Functional events become faults.
(2) Early failures before normal use by the user are not considered to be faults because they are outside the specified intercept range.
(3) Local minor faults that are temporarily unrelated or have little impact on the function of the whole machine are not counted as faults.
(4) Misuse failures caused by improper operation are not counted as failures.
Before data acquisition, the CNC lathe failure mode must first be clarified. While referring to the "Criteria for Reliability Evaluation of CNC Lathes", we have developed a numerical control lathe failure mode table (Table 1) according to the characteristics of the CNC lathe and the actual conditions in use.
The national key scientific and technological projects in the Ninth Five-Year Plan.
According to the determined test plan, data acquisition is carried out as follows: sequence number failure mode serial number failure mode moving parts crawling moving parts shaking moving parts abnormal sound moving parts brake failure moving parts gap excessive moving parts moving moving parts too tight moving parts Knocking moving parts, shifting failure, moving parts, over-speed moving parts, falling-off vibration, affecting workpiece quality, electromechanical interlocking mechanism, malfunctioning, locking parts, failure, fasteners, loosening, pre-tightening mechanism, loose positioning, failure, clamping device, failure, clamping device, early clamping, clamping device Loosen the clamping device in advance, the clamp is not tight, the clamping device is loose, the component is damaged, the component is zero, the component is deformed by zero, the component is loose, the component is detached, the bearing is damaged, the transposition is not operated, the transposition is not in place, the overtravel geometric accuracy exceeds the standard positioning accuracy. Exceeding standard work accuracy exceeds standard performance parameter drop back to zero is not allowed orientation is not allowed coordinate origin drift noise exceeds standard temperature rise too high gas, liquid control failure liquid, gas, oil leakage liquid, gas, oil blockage liquid, gas, oil component Damage to the seal damage to the guard plate, damage to the shield, protective door switch damage, the CNC system does not work properly The program is not executed according to the program instructions, the parameter memory function is disordered, the data transmission error, the component function is lost, the component malfunctions, the component is damaged, the component parameter drifts, the motor does not start, the motor cannot work normally, the motor overload motor is damaged, the false alarm line, the cable contact bad line, Cable break circuit, cable short-circuit fuse damage sensor parts failure wear parts overdue damage turret index inflexible air switch jump N parameter wrong other (1) reference "CNC lathe reliability assessment method", we compiled "CNC lathe The failure analysis report (Table 2) tracks each test lathe separately.
Workshop team year, month, day, equipment, equipment, equipment, age, equipment, equipment, equipment, name, fault, serial number, working environment, failure, failure, cause, treatment, start time, time, end, time, time, time, total, time, time, repair, repair, equipment, equipment, user, "CNC lathe failure analysis report" 》 Fill in the instructions: 1 From the beginning of the test, record the fault of the tested lathe, the second fault occurs, fill in the fault analysis report.
2 Fill in the fault serial number in the order in which the fault occurred.
3 The signatory is required to sign, and the user unit is stamped with the official seal to ensure the data is true and reliable.
(2) Set up an execution plan with the cooperative manufacturer, and the manufacturer will send a special person to fill in the failure analysis report. Once the fault occurs, immediately fill in the report according to the fault criteria and fault type, and continue to observe after the recovery.
(3) Conduct mid-way inspections at regular intervals to understand the situation on the spot and provide guidance on specific issues.
The main data items obtained from the field test are shown in Table 2. In this way, the reliability database of the CNC lathe can be established as needed to meet different data analysis requirements.
4 CNC lathe reliability database establishment reliability analysis is based on a large number of field data, only on the basis of real and reliable data, we can carry out fault analysis, reliability design, etc., in order to design and use the machine tool. Reasonable improvement suggestions such as maintenance. The accumulation of reliability data is a long-term and arduous process. In this process, the data must be effectively organized and managed, which is difficult to do by hand, and must rely on computer database technology. A database can be understood as a set of data that is operational on a computer and that is serviced by multiple users in one or more units. There are currently three popular types of databases: hierarchical, network, and relational. We used the relational database management system FOX PRO to establish a CNC lathe reliability database.
The main purpose of establishing the reliability database of CNC lathe is as follows: (1) Provide important information for the evaluation of reliability index of CNC lathes (2) Provide basic data for fault analysis and reliability design (3) Improve the maintainability of CNC lathes and improve Information on the effectiveness of the use of CNC lathes (4) Establish fault files for CNC lathes for comparison and prediction.
CNC lathe controllable lathe reliability database data structure serial number name type width serial number name type width machine code machine tool type machine name use manufacturer manufacturer fault phenomenon fault cause processing method fault date character date repair date fault time repair time repair time maintenance work time failure mode Fault Location Accumulation Time Fault Code Date The numeric character and numeric characters are used to meet the needs of data analysis. The field names it contains are different from the record item names in Table 2. Some of the fields are now explained as follows.
Fault date: The specific date when the CNC lathe fails (Year/Repair date: The specific date when the CNC lathe returns to normal operation. The fault time: The specific time when the fault occurs (Unit: h) Repair time: The specific time when the machine tool resumes normal operation Time (single repair time: refers to pure repair time (unit: Taiwan time) code name code name main drive system X feed system B axis feed system servo control unit cooling system table chuck and clamp spindle assembly Y feed System shaft feed system hydraulic system chip removal system exchange workbench other turret (tool magazine) Z-feed system N system pneumatic system power supply overall protection unknown manipulator A axis feed system PL system lubrication system external interface electrical system fault location: The faulty subsystems and components are represented by codes. The specific codes are shown in Table 4. Maintenance Hours: Hours of work (units: working hours) accumulated during maintenance: From the beginning of the test to the total working time of the faults Fault code: fault The fault serial number in the analysis report is composed of 8 digits, as shown in the figure on the right: According to the above data structure and internal coding method, the database file DAT ABAS. DBF is created. The following index files are generated by the database file DATABAS. DBF: IDX, etc. Using these index files, we can follow the data in the database according to the machine tool and the manufacturing plant. , use the factory, failure mode, fault location and other fields for retrieval or data reorganization to meet the data analysis requirements for different purposes.
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3 Yi Shangfeng. Research on reliability of CNC lathes. Jilin University of Technology master's degree thesis, the author: JIA new, No. 30, School of Mechanical Engineering, University of Science and Technology Beijing, College Road, Haidian District, Beijing, Zip Code: 100 083 (editor Dong Yaping)
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