Views:1 Author:Site Editor Publish Time: 2021-03-29 Origin:Site
"Lightweight" was originally proposed in the automotive industry. Due to the correlation between vehicle weight and fuel consumption, "lightweight" has gradually led the trend of vehicle design. Since then, the "lightweight" trend has spread to other manufacturing industries, such as crane design and manufacturing. In order to meet actual needs, modern hoisting machinery is developing in the direction of large lifting capacity. Lightweight technology is to reduce the weight of the crane while ensuring the weight of the crane. The weight of Chinese cranes is usually 20%-50% heavier than foreign cranes. Based on this, we can see that there is a huge weight gap between Chinese cranes and European cranes. In terms of lightweight crane design, China still has a lot of room for improvement.
The lightweight of cranes is mainly reflected in five aspects:
(1) The crane design method is usually the allowable stress method. In order to ensure the safety of crane products, a larger safety factor is usually used in the actual design, which leads to the increase of the weight of the crane product and the larger size, resulting in a waste of resources. The limit state design method should be widely used to improve the calculation accuracy and make the calculation results closer to the state of the metal structure in actual work; modern design methods such as finite element method and fuzzy optimization design should be used to analyze and dynamically simulate the mechanics and dynamics of steel structures. Material properties.
(2) For the non-mainly stressed components in the crane, I-beam, channel steel, etc. can be used; welding structures can be used instead of castings, and welding techniques such as robot welding are used. Compared with manual welding, it can ensure the quality of welding at the same time. It can reduce the use of solder: heat treatment and other processes are used to improve the surface strength of crane gears and other components to ensure that the crane has sufficient safety when the structure is optimized.
(3) In order to ensure the safety of the designed products, designers often increase the thickness of the steel plate and design additional reinforcement structures, thereby increasing the weight of the lightweight crane. Related foreign crane companies use aluminum alloy materials to manufacture the main components of cranes. Compared with steel cranes, aluminum alloy cranes can reduce weight by more than 30%: different materials are used for different types of components, and H-type is used as much as possible. Replacing plates with steel saves structural steel and improves the bending strength of the structure.
(4) Traditional cranes can be divided into truss-type and box-shaped structures. They usually use section steel and steel plates as the main components. The connection of different components is realized by welding or threaded connection. These structures emphasize stability and safety. With less economic considerations, steel sections are used instead of welded beams: a flexible trolley frame is adopted, and the "Tic Tac Toe" beam structure is changed to an "I-shaped" beam structure; the overall height of the trolley is reduced, and "all-in-one" is adopted "The trolley operating mechanism, in this way, under the premise of ensuring structural stability and safety, part of the crane structure has been improved to reduce the crane's own weight.
(5) Improve the crane structure and electrical system, adopt a compact lifting mechanism, select high-speed motors and use a brake with a small braking torque; use frequency conversion speed regulation technology to improve the energy-saving effect of the crane; the lifting mechanism can be electric Hoist; select the appropriate magnification according to the different lifting height and lifting speed.
Then, how to realize the "lightweight" of the crane?
can proceed from three aspects: lightweight structural design, lightweight application of new materials and new processes, and enhancement of computer design effects.
Lightweight structure design mainly focuses on the optimization of crane specifications and models. It is usually necessary to ensure the structural strength and functional design of the crane machinery to make the crane structure more compact and lightweight as possible.
The lightweight applications of new materials and new processes are mainly to replace existing materials with lightweight materials such as aluminum, magnesium, ceramics, plastics, and carbon fiber composite materials, and to improve, promote and promote the corresponding lightweight design through new processing and manufacturing processes. achieve.
As for the enhancement of the design effect of the computer, it is mainly because the computer can play more accurate and complete functions in the design of the crane with its huge computing power, especially the computer functions such as finite element analysis method and local enhancement design.