[Lifting machinery] Structure of lifting machinery Safe operation of lifting machinery
Structure of lifting machinery
Lifting operation is an industrial process of transporting mechanical equipment or other objects from one place to another. Most lifting machinery starts a vertical or vertical and horizontal working stroke after the spreader retrieves materials. After arriving at the destination, it is unloaded, and then empty travels to the picking location to complete a working cycle, and then carries out the second lifting. Generally speaking, when the lifting machinery is working,the picking, transporting and unloading are carried out in sequence,The work of each corresponding mechanism is intermittent. sexual. Hoisting machinery is mainly used to transport items. When equipped with a grab bucket, it can transport bulk materials such as coal, ore, and grain. When equipped with a bucket, it can lift liquid materials such as molten steel. Some lifting equipment such as elevators can also be used to carry people. In some use cases, lifting equipment is also the main operating machinery. For example, cranes used for loading and unloading materials in ports and stations are the main operating machinery.
Working Principle of Hoisting Machinery
The hoisting machine lifts or lifts and moves through lifting hooks or other fetching devices heavy objects. The working process of lifting machinery generally includes steps such as lifting, running, descending and returning to the original position. The lifting mechanism lifts the heavy objects from the pickup location through the fetching device, shifts the heavy objects through operation, rotation or luffing mechanism, and lowers the heavy objects at the designated location before returning to the original position.
The structure of the hoisting machinery
The working mechanism includes: lifting mechanism, operating mechanism, luffing mechanism and rotating mechanism, which are called cranes. Four major institutions.
(1)The lifting mechanism is a mechanism used to realize the vertical lifting of materials. It is an important part of any crane. It is an indispensable part and therefore the most important and basic mechanism of the crane.
(2)The operating mechanism is a mechanism that realizes horizontal transportation of materials through the operation of a crane or a lifting trolley. , divided into trackless operation and tracked operation, according to its driving methodDifferent types are divided into two types: self-propelled and towed.
(3)The luffing mechanism is a unique working mechanism of the jib crane. The luffing mechanism changes the operating range by changing the length and elevation of the boom.
(4)The rotating mechanism makes the boom rotate around the vertical axis of the crane. Circular space moves materials. The crane achieves the purpose of transporting materials through the individual movement of a certain mechanism or the combined movement of multiple mechanisms.
1, Driver
Driver The device is used to drive the power equipment of the working mechanism. Common driving devices include electric drive, internal combustion engine drive and human power drive. Electric energy is a clean and economical energy source. Electric drive is the main drive type of modern cranes. Almost all rail cranes, lifts, elevators, etc. that operate within a limited range are driven by electric power. Mobile cranes that can move over long distances (such as tire cranes and crawler cranes) are often driven by internal combustion engines. Human power is suitable for some light and small lifting equipment, and is also used as an auxiliary, backup drive for some equipment and as a temporary power for accidents (or accident conditions). [1]
2, Object retrieval device
The pick-up device is a device that connects materials with a crane for lifting and transporting materials by lifting, grabbing, sucking, clamping, holding or other methods. Different types of fetching devices are used according to the different types, shapes, and volumes of the materials to be lifted. For example, hooks and rings are commonly used for finished items; grabs and hoppers are commonly used for bulk materials (such as grain, ore, etc.); cylinders and tanks are commonly used for liquid materials. There are also special hoists for special materials, such as hoists for hoisting long materials Overhead monorail systems cross beams and hoisting electromagnetic chucks for hoisting magnetically conductive materials, which are specially designed for Rotating hooks used in metallurgy and other departments, as well as retrieval devices such as spiral unloading and bucket wheel unloading, as well as special spreaders for containers, etc. A suitable retrieval device can reduce the labor intensity of workers and greatly improve work efficiency. Preventing the hanging objects from falling, ensuring the safety of the workers and ensuring that the hanging objects are not damaged are the basic requirements for the safety of the retrieval device.
3, Metal structure
Metal structures are made of steel rolled from metal materials (such as angle steel, channel steel, I-beam, steel pipe, etc.) and steel plates as basic components, and are assembled into certain groups through welding, riveting, bolting, etc.A steel structure connected regularly to bear the weight and load of the crane. The weight of the metal structure accounts for about 40%～70% of the weight of the entire machine, and heavy-duty cranes can reach 90 %; Its cost accounts for more than 30% of the total machine cost. According to their structure, metal structures can be divided into two types: solid belly type (made of steel plates, also called box structures) and lattice type (generally made of section steel, with common root frames and lattice columns), which form the metal structure of the crane. The basic stressed member of the structure. These basic force-bearing members include columns (axial force-bearing members), beams (bending members) and booms (pressure-bending members). Different combinations of various components form cranes with different functions. Complex forces, heavy weight, many consumables and overall mobility are the working characteristics of the crane’s metal structure.
4, Operating system
Through the electrical and hydraulic systems, the movements of each mechanism of the crane and the entire machine are controlled and controlled to perform various lifting operations. The control and manipulation system includes various manipulators, displays and related components and circuits, and is the interface for human-machine dialogue. The requirements of safe ergonomics are concentrated here. The status of this system is directly related to the quality, efficiency and safety of lifting operations.
The significant difference between a crane and other general machines is its large, movable metal structure and the combined work of multiple mechanisms. Characteristics such as intermittent cyclic operations, uneven lifting loads, inconsistencies in the movement cycles of various mechanisms, non-chronicity of mechanism loads, and cooperative operations involving multiple people have increased the complexity of the crane’s operations and potential safety hazards. Many, the danger range is large. There are many accident-prone points and the consequences of accidents are serious, so the safety of cranes is particularly important.
Safe operation of lifting machinery
1, Hoisting machinery usually has a large structure and complex mechanism, and can complete lifting and horizontal movements. For example, the bridge crane can complete the lifting, trolley operation and trolley operation3 movements; the portal crane can complete the lifting, luffing, slewing and trolley operation 4movements. During the operation, several movements in different directions are often operated simultaneously, which is technically difficult.
2. There are various types of heavy objects lifted by the lifting machinery, and the load is changing. Some heavy objects weigh hundreds of tons or even thousandsTons, some objects are tens of meters long, and their shapes are also very irregular. There are granular, hot-melted, flammable and explosive dangerous goods, etc. The lifting process is complicated and dangerous.
3. Most lifting machinery needs to operate within a large space, and some require Install tracks and wheels (such as tower cranes, bridge cranes, etc.); some need to be equipped with tires or crawlers to walk on the ground (such as truck cranes, crawler cranes, etc.); some need to walk on wire ropes (such as passenger and freight overhead ropeways) ), the space for activities is larger, and the scope of impact in the event of an accident is also larger.
4. Some lifting machinery needs to directly carry people to perform lifting movements on guide rails, platforms or wire ropes. (Such as elevators, lifting platforms, etc.), their reliability directly affects personal safety.
5. Hoisting machinery has many exposed and moving parts, and is often used in lifting operations Direct contact of personnel (such as hooks, wire ropes, etc.) may lead to many accidental hazards.
6. The operating environment is complex. From large iron and steel complexes to modern ports, construction sites, railway hubs, and tourist resorts, there are cranes in operation; workplaces often encounter dangerous factors such as high temperature, high pressure, flammable and explosive materials, power transmission lines, and strong magnetism. , posing a threat to equipment and operators.
7. Hoisting machinery operations often require the cooperation of multiple people. An operation requires the commanding, binding, driving and other operating personnel to cooperate skillfully, coordinate their movements, and take care of each other. Operators should have the ability to handle on-site emergencies. Close cooperation between multiple operators is usually difficult. The above working characteristics of the lifting machinery determine that it has a close relationship with safe production. If there is any negligence in the design, manufacturing, installation, use and maintenance of lifting machinery, it may cause casualties or equipment accidents. On the one hand, it causes casualties, on the other hand, it also causes great economic losses.
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