Hoisting chain is an essential and important hoisting device of a crane. The length of the chain can be adjusted according to the hoisting height of the heavy object, which plays an important role in improving the working efficiency of the crane and expanding the working scope of the crane. It is mainly used for hoisting hoist and other hoisting equipment, is one of the important hoisting rigging for hoisting and pulling operations. It has been widely used in manufacturing, mining, transportation and other fields.
Hoisting chain specifications and load is in many aspects, there are materials, specifications, grade decided, for example, 26mm*78mm specifications hoisting ring chain, limit working load 21.3T, minimum broken load 850KN. Specifications for 8*24mm hoisting chain, load capacity of 2 tons, strength can reach 80. The surface can be polished, blackened, dipped, hung plastic, electroplating treatment.
What are the common heat treatment methods of hoisting chain
Annealing, normalizing, hardening, tempering, carburizing, nitriding, carburizing, boronizing. Aging treatment has artificial aging treatment, natural aging treatment. Natural aging treatment, the workpiece placed at room temperature or natural conditions for a long time storage and aging phenomenon, known as natural aging treatment. Artificial aging treatment, the workpiece is heated to a higher temperature, and a shorter time for aging treatment of aging treatment process, called artificial aging treatment.
1. Annealing: heat the chain to 30-50 degrees above Ac3, keep it warm for a certain time, and cool it in the space with the furnace slowly to 500 degrees below.
2. Normalizing: An operation in which the chain is heated to above Ac3 or Acm and then removed from the furnace for cooling in the air after insulation.
3. Quenching: Heat the chain to more than Ac3 or Ac1, and cool it quickly in water or oil and other coolant after heat preservation to obtain unstable structure.
4. Tempering: heat treatment process of reheating the hardened hoisting chain to a temperature below Ac1 and cooling it to room temperature after heat preservation.
Description of hoisting chain
1. Transmission chain: mainly used for transmission of power chain.
2. Conveying chain: mainly used for conveying materials.
3. Drag chain: mainly used for dragging and hoisting chain.
4. Special special chain: mainly used for special mechanical devices, with special function and structure of the chain.
The hoisting chain adopts forging because the mechanical properties of castings are lower than those of forgings made of the same material. Because the structure and properties of the metal after liquefaction have completely changed, in addition, forging processing can ensure the continuity of the metal fiber organization, so that the fiber organization of the forgings is consistent with the shape of the forgings, and the metal streamline is complete.
Hoisting chain forging can ensure that the chain ring has good mechanical properties and long service life, the use of precision die forging, cold extrusion, temperature extrusion and other processes to produce forgings, are incomparable to the casting forgings are metal pressure, through plastic deformation to shape the required shape or the appropriate compression force of the object. This force is typically achieved by the use of a hammer or pressure.
It seems that the hoisting chain after forging not only can ensure its strength, but also can further increase the compactness of the internal structure, so that its density is further, the strength also increases a lot, which is unable to do casting, so the hoisting chain will use forging treatment more.