Automatic lock screw machine is through various types of electric, pneumatic components to achieve automatic screwing, screwing, testing and other processes, through the equipment to simplify the screw fastening process, to reduce the number of labor and reduce the adverse factors caused by manual misuse. Is a typical non-standard automation equipment. Automatic Bench Locking Screw Machine Automatic Bench Locking Screw Machine,Locking Screw Machine Dongguan Jaten Instrument Co.,LTD(HK TT:Jaten Technology Co.,Ltd ​) , https://www.jatentech.com
During the design process, by analyzing various factors that may cause system failure, including hardware, software, environment, human factors, etc., draw a logical block diagram (ie, fault tree) to determine various possible combinations of system failure causes and The probability of occurrence, in order to calculate the probability of system failure, take corresponding corrective measures, and improve the reliability of the system.
With the continuous advancement of modern science and technology, the work undertaken by many machines and systems is becoming more and more complicated. The products are used in a wider range of places and the environment is more severe. The purpose of complication is to make the technical equipment have higher performance. However, the complication of equipment will cause a significant increase in the chances of failure of the entire system due to failure of any part of each other, and the entire system failure will cause economic risks and even personal safety risks. Therefore, there is a sharp contradiction between complexity and reliability. Reliability is an important indicator for measuring product quality. It is a big problem that directly affects production, economy and personal safety. Therefore, it is highly valued abroad and is as amazingly developed as computer and environmental science.
China's application research on mechanical product reliability theory and technology started late. In view of the high failure rate, low life span, poor maintainability and high maintenance cost of some major mechanical products in China, the application research of reliability technology is carried out in time. Improving the quality of mechanical products is an urgent task. Cylindrical gear reducers are widely used in mechanical systems. Its stability directly affects the performance of the entire mechanical system. It is of great significance to study its reliability.
2 Cylindrical gear reducer system fault tree establishment Before the establishment of the system fault tree, the definition of the reliability of the cylindrical gear reducer is given: the life that can be operated normally under the allowable working load and speed and other specified working conditions. Generally, the performance evaluation of the spur gear reducer has the following indicators: 1) bearing capacity (power and torque that can be transmitted); (2) torque in the transmission ratio range, multiple of the speed reduction); 3) transmission efficiency (or power) Loss) (4) Smoothness of operation (vibration) (5) Noise; (0 life. Among them, the first five conditions are performance indicators, and the sixth indicator is that the reliability index is more scientific and easier to assess. In fact, If there are many faults and the life is not guaranteed, even if the above five performance indicators such as carrying capacity and efficiency are advanced, it does not make any sense. Mistakes in design, manufacturing, and maintenance will be potential factors for failure. Quantitative reliability indicators are necessary.
The fault tree is based on the causal relationship between the system and the components. Using various logic gates to use the deductive method to organically connect the top event and the intermediate event to each related basic event into an inverted event tree. The most undesired event is usually called the top event (that is, the system failure), and the event that is decomposed into no longer decomposable is called the bottom event. The top event of the system is the failure of the reducer and the fault tree of the system. The bottom event (fault link) represented by A to M is shown in Table 1.
Table 1 overload fatigue rubber plastic peeling tooth surface point installation normal cooling oil-free oil circuit fault deformation deformation wear failure wear device oil unqualified plug failure 3 qualitative analysis of the fault tree Any set of basic events that can cause the top event to occur is called A cut set, which is a collection of minimal basic events that can cause a top event to occur. The minimum cut set solution of the fault tree is a top-down fault tree search method (ie, Fussell algorithm). According to the logic and the gate only increase the cutting capacity, the logic or the gate increases the number of cut sets. When the AND gate meets, the input events under the AND gate are arranged in a row. When the OR gate is encountered, the input events under the OR gate are arranged into One column until it can't be decomposed. The following is the minimum cut set of the fault tree () solved by the Fussell algorithm. The results are shown in Table 2. Table 2 AKMALUAM is generated by the AND gate, that is, when the two events occur simultaneously, the upper event will occur; Events are generated by OR gates, that is, any one event will cause a system top event to occur. Engineeringly, the minimum cut set characterizes the sufficient and necessary conditions for system failure. The number of basic fault events that make up the minimum cut set is the order of the minimum cut set. The smaller the order, the greater the impact of the minimum cut set on system failure.
It can also be seen from the minimum cut set that A overload and B fatigue fracture appear 5 times and 4 times respectively, which have a great influence on the occurrence of the top event, which is also in line with the fact that overload and fatigue fracture occur in the cylindrical gear reducer. The most likely cause of the failure.
4 Reliability analysis of cylindrical gear reducers According to the Fussell algorithm, the minimum cut set can be obtained, in many cases more than one. The element in the minimum cut set is the logical AND relationship, that is, the fault occurs when every event in the minimum cut set occurs. The ratio of the product of the failure probability of each element of the minimum cut set to the top event failure probability (ie, the minimum cut set importance) can be used as the sorting criterion of the minimum cut set, and the minimum cut set importance is prioritized. Since the failure probability of the mechanical component is difficult to obtain, the minimum cut set importance is calculated by approximating the failure probability of the component (bottom event).
Before solving with the minimum cut set, make the following assumptions: (1) the bottom events are independent of each other; (2) the bottom event and the top event only consider two states: occurrence or non-occurrence, that is, normal and fault states; 3) The probability of failure of the bottom event is Ci is the minimum cut set of the known fault tree, ie: Ci = A, C2 = B, ..., cB = AM; where the bottom event p (> 0 = l - eM. Know that for the exponential distribution value, you can get the probability of failure of the system: Pa) = P (A + B + ... + AM) i = Therefore, the reliability of the column gear reducer system R = 1 - P (T) can be Calculated. Where t is the continuous working time of the column gear reducer.
5 Conclusion Through the analysis method of fault tree, it is concluded that A overload and B fatigue fracture are the most likely causes of failure of the column gear reducer. It also provides a formula for quantitative calculation of the reliability R of the column gear reducer system, namely: R=1-P(T). This method provides an idea for the detection and analysis of column gear reducers and similar systems, finding fault sources, and predicting possible failure causes. In this way, precautions can be taken against possible failures, designed and manufactured in a targeted manner to effectively improve product quality, safety and cost.
Lu Tingxiao, Zheng Pengzhou. Reliability design and analysis. Beijing: National Defense Industry Press, Zhu Jizhou. Fault tree principle and application. Xi'an: Xi'an Jiaotong University Press, Li Guangfu. Reliability analysis of cylindrical gear reducers. Technical supervision of the petroleum industry, Zhu Dage. Research on fault diagnosis method based on minimum cut set of fault tree. Data collectors refer to the march (5 male, postgraduate students, the main research direction is computer integrated manufacturing and manufacturing information, mechanical system testing and control.
Yang Mingzhong (1943-), male, professor, Ph.D.
Automatic lock screw machine is mainly divided into: hand-held lock screw machine, multi-axis automatic lock screw machine, coordinate automatic lock screw machine.
The automatic lock screw machine is mainly used for locking the M1-M8 screws. Because it belongs to non-standard automation equipment and has customizable features, products involving screw fastening can obtain corresponding solutions and have a wide range of applications.
Research on Reliability of Cylindrical Gear Reducer Based on FTA