Mechanical Engineering Handbook: Special Machinery Volume (II)

Author: Chief Editor: Qi Fujiang
Publisher:
Publish Date: 1997-11-01
Features: The Mechanical Engineering Handbook (Second Edition) consists of 18 volumes and 152 chapters, divided into Basic, Engineering Materials, Design, Processes and Equipment, Electrical and Electronic Instruments, General Mechanical Products, and Specialized Machinery. This volume is part of the Specialized Machinery section. It includes 5 chapters: Engineering Construction Machinery, Mining Machinery, Metallurgical Machinery, Petroleum Drilling and Refining Machinery, and Chemical Engineering Machinery. This handbook is primarily intended for a broad range of mechanical engineering technicians with intermediate to advanced technical skills, serving as a reference for comprehensive research and handling of technical issues in their profession and related fields. It can also be used as a reference for university teachers and students, as well as other relevant personnel.
Excerpt:
Chapter 1 Introduction Machinery used for earthwork, rockwork, lifting and loading, and mechanized construction and operations in various engineering projects are referred to as engineering construction machinery.
1 Classification of Engineering Construction Machinery Engineering construction machinery is classified based on its product function, structural characteristics, and usage scenarios as follows:
1. Excavating Machinery Used for excavating earth and loading blasted rock. Includes cyclic and continuous operation types.
2. Earth-moving and Loading Machinery Through interaction with the ground via the walking mechanism, it performs earth excavation, leveling, and short-distance transportation. Includes bulldozers, loaders, scrapers, grinders, and dump trucks.
3. Engineering Hoisting Machinery Through the composite motion of vertical and horizontal movements of the hoist hook, it converts the position of heavy objects according to engineering requirements. Includes truck-mounted cranes, tire-mounted cranes, crawler-mounted cranes, and tower cranes (see Material Handling Equipment Volume, Part 2).
4. Compacting Machinery Used to enhance the density of media (soil and mixed materials). Includes road rollers and tamping machines.
5. Piling Machinery Used for pile foundation engineering. Includes pile drivers and drilling machines.
6. Industrial Material Handling Vehicles Composed of self-propelled wheeled chassis and working or carrying units, primarily used for internal transportation and loading in ports, stations, warehouses, and various enterprises. Includes various forklifts, stackers, transporters, straddle carriers, AGVs, and tractors (see Material Handling Equipment Volume, Part 4).
7. Decoration Machinery Used for interior and exterior decoration of buildings. Includes mortar preparation and spraying machines, coating spray machines, ground grinders, roof construction machinery, decorative platforms, scaffolds, building handheld tools, and other decoration machinery.
8. Rock Drilling Machinery Used for drilling holes in parent rock and ore for blasting. Includes rock drills, rock drilling rigs,s, and breakers.
9. Pneumatic Tools Used to replace manual operations in industrial production support tasks, powered by compressed air. Includes rotating, impact, and other pneumatic tools.
10. Pavement Machinery Used for construction and maintenance of road subgrades and pavement layers. Includes subgrade construction machinery, asphalt pavement construction machinery, cement pavement construction machinery, and maintenance machinery. This type of machinery is also widely used in airport, port, sports field, and plaza construction projects.
11. Reinforcement Machinery Used for processing reinforcement bars in the production of prefabricated concrete components and in concrete construction. Includes reinforcement straightening, bending, cutting, tying, prestressing, and welding equipment.
12. Concrete Machinery Used for the preparation, transportation, pouring, and vibration of concrete in construction. Includes concrete mixers and batching plants (concrete preparation machinery), concrete pumps and concrete transporters (transport machinery), and various vibrators and vibration tables (vibration machinery).
13. Railway Line Machinery Used for laying, dismantling, replacing, and maintaining railway tracks.
14. Municipal Engineering Machinery Used for municipal engineering construction and operations. Includes greening machinery, waste collection machinery, and street sweeping machinery.
2 Characteristics of Engineering Construction Machinery Engineering construction machinery has the following characteristics:
(1) Wide range of working environments, harsh conditions. The working and operational environments of engineering construction machinery vary greatly, from plains to plateaus, from tropical to cold regions, from rainy swamps to arid deserts, from open areas to underground, from land to underwater, etc. The climatic and geographical geological conditions differ significantly, requiring the performance and quality of engineering construction machinery to have broad environmental adaptability. The working objects of engineering construction machinery are diverse, such as soil and rock for excavating machinery. Soil includes hard soil, soft soil, weathered rock soil, and frozen soil, with excavation resistance varying by more than 10 times. Rock includes gravel, blasted rock, and various ores. Therefore, the operational load on excavating machinery is complex and highly random, with severe vibration and wear. Additionally, engineering construction machinery often operates in the field, exposed to dust, large temperature differences, and wind and rain, resulting in harsh operating conditions. Thus, engineering construction machinery requires extremely high reliability, a well-designed cab for safety and comfort, and special requirements for dustproofing and corrosion resistance.
(2) Great differences in specifications among similar engineering construction machinery, such as the driving power of crawler-mounted bulldozers ranging from 40 kW to 1,000 kW, the bucket capacity of single-arm hydraulic excavators from 0.02 m3 to 34 m3, and the lifting capacity of truck-mounted cranes from 5 t to 1,000 t. This is determined by the different working objects and types of engineering requiring varying construction and operational requirements.
(3) One machine with multiple interchangeable working units. To reduce product costs and meet the needs of various construction and operational tasks, different working units are replaced on the same chassis to achieve different types of construction and operations. For example, on a single-arm hydraulic excavator chassis, various units such as backhoes, front shovels, grabs, hoisting units, log grabs, breakers, pile drivers, and drilling machines can be exchanged. Similarly, on a loader chassis, log clamps can be replaced for wood loading, and large forklift units can be installed to achieve different functions in forest loading and off-road forklift operations. Some types of engineering construction machinery can even install two working units simultaneously on the same chassis. For instance, an excavator-loader installs a backhoe at the rear of the wheeled chassis and a loading unit at the front, serving as both an excavator and a loader. A crawler-mounted bulldozer installs a ripper at the rear, capable of both ripper and bulldozer functions.
(4) Use of complete sets of products among various types. General construction projects involve multiple process steps, and a single engineering construction machinery often cannot complete all tasks. It is necessary to use corresponding different products for continuous operation of different processes to complete the entire project. Only when the functions and operational rates of different machine types are scientifically matched can continuous mechanized construction be carried out rationally and economically, improving efficiency, shortening production cycles, and reducing costs. Depending on the specific construction requirements of different projects, complete sets of engineering construction machinery can be used for comprehensive mechanized construction, partial products can be used for mechanized construction of certain processes, or single machines can be used for mechanized construction of critical processes.
3 Development Trends of Engineering Construction Machinery
(1) Specialized production of components is expanding and developing. Engineering construction machinery has many varieties, with relatively small production batches for each type. Through optimized design, the generalization rate of major components can be improved, increasing production batches, quality, and reducing costs. Examples include torque converters, power-shift transmissions, general transmissions, various clutches and brakes; drive axles and steering axles, track assemblies, torque limiters, forklift forks and masts, instrument panels, cabs, driver seats, bucket teeth, and cutting edges, each with unique manufacturing processes, suitable for specialized batch production. The market for general components of engineering construction machinery is expanding and developing, with the self-production rate of original equipment manufacturers gradually decreasing, generally below 40%.
(2) Safety and protection devices are becoming increasingly perfect. To protect the operator's safety, anti-overturning cabs are being increasingly used on engineering construction machinery such as bulldozers and loaders during driving and operating tasks. Torque limiters are widely used on engineering cranes to ensure safe operation. Various electronic alarm devices are also being developed and improved, with remote control and unmanned driving of engineering construction machinery being developed for special environmental construction and operations.
(3) Products are developing toward both large-scale and miniaturized extremes. From the perspective of improving economic efficiency, projects such as mines and power plants are becoming increasingly large; from the perspective of reducing labor intensity and saving labor, various small-scale decentralized projects in cities and rural areas also use engineering construction machinery for construction. This situation determines that engineering construction machinery products will develop in both directions—toward large-scale and miniaturized. For example, wheeled loaders will develop products with bucket capacities above 5 m3 and small products below 0.5 m3. Crawler-mounted bulldozers will develop products with driving power above 400 kW and small products below 80 kW. Single-arm hydraulic excavators will develop products with bucket capacities above 8 m3 and small products below 0.4 m3.
Chapter 2 Basic Theories and Common Technologies of Engineering Construction Machinery
1 Ground Mechanics Ground mechanics primarily studies the interaction between the walking and working units of engineering construction machinery and soil, as well as their travel performance and operational performance (e.g., compaction, cutting), providing a theoretical foundation for product design and use. Soil consists of solid particles, as well as the liquid and gas between particles. Depending on different conditions and research purposes, soil can be assumed to be an elastic body, an elastoplastic body, a viscoelastic body, and a viscoplastic body, etc. For example, soil stress analysis during cutting or compaction assumes soil as an elastic body; during vibration compaction analysis, soil is assumed as a viscoelastic body, etc.
1.1 Principles of Soil Cutting
1.1.1 Cutting Elements and Soil Cutting The cutting elements of working units such as the blade of a bulldozer and the bucket of an excavator (Figure 1.2-1) are generally wedge-shaped blades, which can be toothed or smooth. The working surface is usually flat, and the blade edge is straight. The geometric parameters (Figure 1.2-2) include the cutting angle α, edge angle β, and rear angle δ, while the working parameters include cutting depth h, cutting width b, and cutting speed v.