Modern construction machinery inspection and maintenance

Author: Chief Editor: Wang Qian et al
Publisher:
Publish Date: 1996-03-01
Features: Brief Introduction This book is compiled based on the principle of combining theory with practice, with a focus on practicality. In terms of theoretical explanations, it strives to be concise and to the point; in practical technology and the inspection and repair of typical construction machinery, it strives to be comprehensive, accurate, and detailed. The book focuses on preventive maintenance and fault detection. The entire book is divided into seven parts, totaling thirty-four chapters. Part 1 introduces the concept of mechanical aging and renewal technology, as well as economic analysis of maintenance. Part 2 discusses non-destructive testing, oil sample analysis, and vibration technology. Part 5 covers the repair techniques of parts. Parts 6 and 7 collect typical cases of fault diagnosis and non-destructive inspection of some construction machinery introduced in China since the 1980s. Excerpt: Chapter 1 Repair Organization Section 1 Mechanical Aging After being produced, machinery begins a gradual aging process until it is scrapped during storage and use. Studying the regularity of this aging process and exploring corresponding countermeasures that adapt to this regularity are the core content of mechanical repair science and the theoretical foundation guiding mechanical maintenance production. Section 1 Classification of Mechanical Aging 1. Tangible Aging The phenomenon where the physical integrity of mechanical parts deteriorates due to wear, deformation, fracture, or corrosion, resulting in reduced precision and performance, is called tangible aging. Among these, the first type of tangible aging refers to physical damage caused by wear, deformation, fracture, or corrosion during the operation of machinery. The second type of tangible aging refers to physical damage caused by natural forces such as metal rust, decay of wood and leather, or aging of rubber and plastic during idle periods. The first type of tangible aging is related to usage time and intensity, while the second type is related to idle time and storage conditions. Improving design, enhancing processing quality, adopting new durable materials, proper use, reasonable maintenance, and diligent storage can all delay the progress of tangible aging and extend the life of machinery. 2. Intangible Aging The phenomenon where the utility or reproduction cost of machinery decreases due to technological progress during use or idle periods is called intangible aging. The first type of intangible aging refers to a situation where the technical structure and economic performance of the equipment remain unchanged, but due to technological advancements, continuous improvements in production processes, or reduced costs of reproducing the machinery, the machinery becomes devalued. The second type of intangible aging occurs when new machinery with improved structure, better technical performance, higher productivity, and better economic efficiency is introduced, making the existing machinery technologically obsolete if continued in use. In technological development, if new materials are widely adopted or entirely different construction methods are used, the existing machinery may completely lose its utility and be phased out, resulting in rapid aging. It should be noted that intangible aging is a result of social productivity development. The faster the aging, the faster the technological progress of society, and it should be welcomed. Therefore, the task of mechanical maintenance personnel is not to prevent the intangible aging of machinery but to carefully study the laws of intangible aging and take appropriate measures to adapt to technological development. Section 2 Quantitative Indicators of Mechanical Aging Degree 1. Quantitative Indicators of Tangible Aging (1) Indicators of Part Aging Dominated by Wear The calculation formula for the aging degree of parts dominated by wear is as follows: In the formula, α represents the aging degree of the part; δpT represents the actual wear amount of the part; δm represents the maximum allowable wear amount of the part. (2) Indicators of Part Aging Dominated by Fatigue The calculation formula for the aging degree of parts dominated by fatigue is as follows: In the formula, TPT represents the actual operating time of the part; Tm represents the fatigue life of the part. (3) Indicators of Mechanical Aging Degree Based on Part Aging Degree Based on the calculation of the aging degree of each part, the aging degree of the machinery can be determined. In the following formula, economic indicators have greater practical value than physical aging degree.