The solution to the deformation of the black steel seamless pipe during the production process

Black steel seamless pipes are uncoated steel pipes, also known as black steel. The dark color comes from iron oxide that forms on its surface during the manufacturing process. When a steel pipe is forged, a black scale forms on its surface, giving it the finish seen on this type of pipe.

1. Causes

The main reason for the deformation of the black steel seamless pipe during the production process is that the quality of the pipe material is not good, and there is deformation itself.Or there are inclusions, serious scratches and cracks on the surface, and there are edges and corners at the grinding place, which will be deformed by extension after drawing. In order to avoid deformation, the quality of the pipe material should be improved and attention should be paid to inspection and grinding.

2. Solution

1)Free correction and mold correction

Free correction is to place the black seamless steel pipe on a flat plate or a special simple tire mold, and beat it with a hammer until the size and shape meet the requirements. Mostly used for small and medium pieces.Castings are generally straightened on designated straightening equipment. Before the correction, the deformation law of the casting should be mastered, and the necessary correction molds suitable for the geometry and size of the correction part of the casting should be equipped.Mold straightening is to place the casting in the forming mold (generally divided into upper and lower molds), and use the selected pressure on the selected straightening machine to rectify the casting as a whole.During the overall correction, lifting equipment or manipulators are generally used to load or remove the casting into the correction mold. The correction mold for overall correction needs to be specially designed and manufactured, with high precision requirements, suitable for mass production line production, high production efficiency, low labor intensity, and small size deviation of the corrected castings.

2) Cold straightening and hot straightening

Cold straightening is the straightening of normal temperature castings by hammering, manual presses, jacks, friction presses or hydraulic presses. It is suitable for medium and small thin-walled castings with simple geometry and small deformation, or as-cast aluminum alloy castings with large deformation but good plasticity, and quenched aluminum alloy castings with large deformation.When the structure of the casting is complex, it can be corrected with the help of a correction mold. Thermal correction is divided into local heating and overall heating. When cold straightening of some black steel pipe fittings is difficult, it can be corrected by hammering or pressing after local heating.Thick-walled large castings should be corrected by overall heating, and the amount of deformation to be corrected should be measured before correction.Then put it on the horn in the heat treatment furnace, put appropriate pads on it, apply an appropriate load on the part to be corrected, and correct the deformation by the action of the load during the heat treatment process.

seamless pipe means a pipeline with a hollow section and is used in large quantities as a pipeline for transporting fluids, such as pipelines for transporting oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, the steel pipe is lighter in weight when the bending and torsional strength is the same, and is an economical section steel.
It can improve the utilization rate of materials, simplify the manufacturing process, save materials and processing time, and have been widely used in steel pipe manufacturing.

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