Problems and solutions of the reliability of the h

Problems existing in the reliability of construction machinery and solutions (1)

the reason why China's construction machinery is lack of competitiveness is mainly because of the short overhaul life and low reliability. At present, this problem has also attracted the hot attention of the social industry. In view of these problems, China has put forward measures to study the dynamic performance of construction machinery, which can fundamentally solve the problem of reliability, and is conducive to the solution of energy conservation and emission reduction of construction machinery and the quality of operation. This paper will illustrate the basic means of studying the dynamic performance of machinery, such as field test and bench simulation experiment. After some practice and thinking, the author believes that strengthening engineering and using it to express the melt viscosity and mechanical dynamic properties of polymer materials is the fundamental way to solve the problem

1 connotation of reliability of construction machinery

reliability of construction machinery actually refers to the ability of products to complete the specified functions and uses within the specified time and working conditions. However, the guarantee of product reliability is still a comprehensive problem. Improving manufacturing quality and product design is the most fundamental method to solve the reliability of construction machinery

generally, the reliability design should adopt the formal method to increase the safety factor of key parts and ensure some reliability reserves. In general, improving the reliability of construction machinery is conducive to ensuring that the working capacity of products will remain unchanged for a long time. However, since the annual consumption of LDPE in the Indian market will reach 1.2 million tons, it can be said to be a random situation to a certain extent, so the failure can not be avoided. During the service life, the ability of products to ensure working performance under specified maintenance conditions is called product reliability design, which takes improving the durability and durability of products as an important content to improve economic benefits

2 the current situation of the reliability of construction machinery in China

according to the data, the average time between failures (MMF) of international construction machinery products during the 1000 h reliability test and the "two guarantees" period is 500 800 h, while China's level is only L50 ~ 300 h, which is far lower than the international level

if imported engines are not used, the overhaul life of Chinese products is only 4000 ~ 5000 h, while the international level can reach 810000 H. It can be seen that the lack of competitiveness of China's construction machinery is mainly related to the low reliability and short overhaul life

in addition, according to the statistical data, we can see that 30% of the faults of construction machinery in China belong to engine faults; About 25% - 35% of the faults are hydraulic system faults; About 20% of the faults are transmission system faults; The rest are the cracks in the welds of structural parts and the failure of the braking system

3 the main reason for poor reliability

there are many factors that affect the reliability of construction machinery, such as design, materials, manufacturing and use, but the fundamental research is the lack of research on the dynamic performance of the machine. Different from other machines, most construction machines are operated in the field, and the load, working condition and load change are variable, and there are also many harsh requirements such as continuous construction in mechanical engineering. All these require that the reliability and adaptability of construction machinery can be further developed and improved. The so-called dynamic performance refers to the fuel economy, power and operating performance of the machine under the dynamic conditions of changing workload

take the double drum vibratory roller as an example, which is a circulating machine mainly used to compact subgrade materials. When the vibratory roller is in the initial stage, the whole vehicle needs to overcome the translational inertia force of the machine itself when moving from static to constant speed. In addition, whether the steel wheel rotates and vibrates at high speed or runs from static to constant speed, the inertia moment needs to be overcome. However, when the steel wheel and roller bodies belonging to the large inertia pellethane thermoplastic polyurethane (TPU), tecoflex thermoplastic polyurethane (TPU), tecothane thermoplastic polyurethane (TPU), isoplast etpu and carbothane thermoplastic polyurethane (TPU) systems translate or rotate, the external load changes greatly and violently. On the one hand, this will inevitably impact the vibration hydraulic system and walking drive, which will reduce the service life and performance of hydraulic components; On the other hand, the force and torque of the steel wheel on the ground must be replaced and repaired in this city. These benches and other functions change greatly, resulting in the phenomenon of the compactness of quite uneven sections, and even a phenomenon of material displacement. However, the starting process cannot take too much time, otherwise, the effective compaction time will be reduced, and the resonance phenomenon will occur when the steel wheel starts to vibrate and crosses the resonance point, which will greatly damage the machine and the pressed material. Of course, such a similar phenomenon will also exist when the machine stops

at the same time, the external load that changes sharply in the starting stage and parking stage is easy to cause fluctuations in the power and speed of the engine, especially when parking, the huge inertia generated by the machine causes the reverse braking engine, which greatly reduces the reliability and service life of the engine. In addition, it will also affect the service performance of the engine