Deformation Analysis of Seamless Pipe during Empty Drawing

Posted by chase Liu on February 22nd, 2023

There will be deformation when the seamless pipe is drawn, and different deformations will occur in different situations, so what deformation does the seamless steel pipe have?

After emptying, the surface area of the outer surface of the seamless steel pipe increases, while the surface area of the inner surface decreases. And there must be a neutral layer between the inner and outer surface layers, and the surface area has been increased after the deformation of each layer between the outer surface and the neutral layer. The outer surface layer increases the most, and the surface area of each layer between the neutral layer and the inner surface decreases after deformation, and the inner surface decreases the most.

The above-mentioned changing nature of the surface area of each layer of the seamless steel pipe during empty drawing affects the inhomogeneity of metal deformation. One of its characteristics is that the natural extension of the layers along the pipe wall is inconsistent. The natural extension is the smallest on the outer surface layer of the seamless steel pipe, the largest on the inner surface layer of the seamless steel pipe, and the natural extension of the middle layers gradually increases from the outer surface layer to the inner surface layer. The second feature is that due to the relationship of integrity, the layers of the seamless steel pipe cannot have different extensions during deformation, so the layers must be mutually restrained.

Since the natural extension of the metal between the outer surface and the neutral layer (called the outer layer) is smaller than that of the metal between the neutral layer and the inner layer (called the inner layer), the outer layer must be restrained by the inner layer during deformation. Its actual extension is larger than the natural extension, and its thickness is reduced due to the increased extension. Instead, the extension of the inner layer is hindered by the outer layer, whose actual extension is smaller than the natural extension, while the thickness increases.

Seamless steel pipe is a steel pipe that is perforated by a whole round steel and has no welds on the surface. According to the production method, seamless steel pipes can be divided into hot-rolled seamless steel pipes, cold-rolled seamless steel pipes, cold drawn seamless tubing, extruded seamless steel pipes, and pipe jacking. According to the cross-sectional shape, seamless steel tubes are divided into two types: round and special-shaped, and special-shaped tubes have various complex shapes such as square, oval, triangular, hexagonal, melon-shaped, star-shaped, and finned tubes. Steel pipe dimension has a maximum diameter of 900mm and a minimum diameter of 4mm.