The firework process is a technology used to deal with thermal deformation, that is, heat treatment of steel, when the steel rises to a certain temperature, through firework processing and distortion correction by flame, the steel is formed into a specific shape. Since modern steel ships need to use a large number of corrective deformations in the manufacturing process, and the volume and mass of steel ships are relatively large, only firework can be used to correct the deformation.

 

 

The bending plate

 

1. Firework processing

 

Firework processing can be divided into two main methods, one is the overall heating and bending method, and the other is the local heating and bending method. The method of overall heating and bending refers to the overall heating of the workpiece placed in the heating furnace. The steel will be heated to a certain temperature, the strength will be reduced, and the plasticity will increase. At this time, the workpiece is forced to be bent, and the temperature of the workpiece is cooled, It will become a curved shape.

 

 

There are two main processing techniques for local heating and bending in hull buildings, namely flame bending and water-fire bending. Oxygen-acetylene flame is used when flame bending is used to process the workpiece, and the steel has the characteristics of thermal expansion and contraction. When the steel is heated to a certain temperature, the workpiece will be bent into shape; Sprinkle cold water on the workpiece to make the workpiece bend into shape.

 

 

2. Distortion correction by flame

 

The basic principles of distortion correction and firework process are the same, but the two constraints are different. Distortion correction can be regarded as the inverse process of pyrotechnics processing. Distortion correction is to correct the deformation by firework in the already deformed structure, thereby forming a new permanent deformation. To successfully complete the distortion correction, the local heating area of the component must be supplemented and the local heating area of the component must be enlarged.

 

 

The final result is that the metal heating part is affected by the characteristics of thermal expansion and contraction during heating, thereby forming permanent deformation. When the process is over, the part of the metal that is not heated by means will produce tensile stress. Under this action, the deformed structure will also deform, and eventually return to straightness. The magnitude and distribution of this tensile stress largely affect the quality and effect of structural correction, and the resulting stress state is determined by the heating form.

 

 

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