With the continuous progress of science and technology and the rapid development of modern production, the role of machinery and equipment as an important factor in determining the output, quality and cost of product production is becoming more and more obvious. The pants pulling machine will inevitably produce different degrees of wear, fatigue, distortion or damage in the process of use. Over time, their technical status will gradually deteriorate and their service performance will decline. As an important part of equipment management, equipment maintenance is an important guarantee to prolong the service time of the machine, ensure the normal operation of production and prevent accidents. By exploring the faults, it is found that most pants pulling machines have similar fault rate curves. This kind of fault curve is often called bathtub curve. According to this failure curve, the change of mechanical failure rate with time can be roughly divided into early failure period, accidental failure period and wear failure period.
Early failure period is also called running in period for mechanical products. During this period, the failure rate was high at the beginning, but the failure rate decreased rapidly over time. The faults occurred during this period are mainly caused by defects in design and manufacturing or improper use. In the period of accidental failure, the equipment failure rate is roughly in a stable state.
During this period, the fault occurrence is random, and its fault rate is stable, which is the normal working period or the best state period of the machine. Most of the failures occurred here are caused by improper design, use and poor maintenance. The failure rate can be reduced in the later stage of equipment use by improving design quality, management and maintenance. The failure rate continues to rise due to wear, fatigue, aging and corrosion of parts and components. Therefore, it is considered that if the overhaul is carried out at the beginning of the wear failure period, the failure rate can be reduced economically and effectively.
With the development of science and technology, a large number of new technologies and materials are emerging, especially the wide application of electronic technology and automation technology. The pants pulling machinery is developing in the direction of precision, automation and modernization. Its structure, the relationship between various work and the environment become more and more complex, which brings new problems to the maintenance work.
Through research, it is found that the fault law of some equipment configured with modern technology deviates from the bathtub curve. After nearly 30 years of exploration, there are five cases of mechanical failure rate of pulling pants in addition to the bathtub curve.
The first case shows a constant or slightly increased failure rate with a significant wear period. The second case shows a slowly increasing failure rate, but there is no obvious wear period. The third case shows that the failure rate of new equipment has increased sharply from the low failure rate just delivered to a constant failure rate. The fourth case shows that the failure of the equipment is a constant value, and the failure is often caused by accidental factors. The fifth case shows that the equipment begins to have a high initial failure rate, and then drops sharply to a constant or extremely slow growth failure rate. However, the mechanical failure rate depends on its complexity. The more complex it is, the closer its failure curve is to the last two cases.
If the mechanical failure of trousers is caused by improper design, use and poor maintenance, the failure rate can be minimized by improving the design quality, improving management and maintenance. If the overhaul is carried out at the beginning of the depletion failure period, the failure rate can be reduced economically and effectively. The observation curve tells us that if the device is prone to early failure, there is no need to worry about random or wear failure, and its service life ends in the early stage of operation itself. In order to keep up with market standards, measures must be taken to provide highly reliable and high-quality products. To ensure this reliability, the first step is to reduce early failures.