SU505455A1 - Method for the production of hot rolled pipes on a machine with an automaton - Google Patents

Description

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The invention relates to pipe production, in particular to the production of seamless hot rolled pipes in installations with automatic mills.

There are known methods for producing hot-rolled pipes on plants with automatic mills, where they roll out the sleeve on a round mandrel successively in several round gauges (cages) or automatic machines, rolling the sleeve in two or three passes with a return to the front table (see ed. № 112973, class B 21L 17/04).

However, the shaping of the liner in the calibres of the automatic machine with two outlets limits the amount of stretching due to the formation of bulges (riots), which leads to the appearance of undercuts and scratches and to an increase in difference after the rolling mill.

A known method of producing pipeless pipes (see French Patent No. 2120229, class B 21L17/00), in which the blank is forgiven with 75–80% reduction, and the sleeve is rolled in one pass with 15-25% reduction. In this case, the area of influence of the gauge of the rolls of the rolling mill is minimized due to the formation of a riot on the surface of the pipes. In order to implement this method, the mandrel of the coaxial forgive mill, consisting of a nozzle and a working part, has an annular recess in the area corresponding to the nip of the rolls. The gauges of the rolls of the automaton are constructed by conjugation of two radii, and the radius at the vertex caliber is larger than the radius at the connector of the rolls. Mandrel automat has a spherical working surface.

In this method, the metal deforming scheme predetermines its flow in the release and, as a result, the transverse difference during rolling remains.

There is also a known method of producing hot-rolled pipes on a machine with an automatic machine, in which a sleeve, obtained by patching on a roll mill, is rolled in one pass in two consecutive cages of the automatic machine, and then rolled on rolling bevel mills.

This method limits the amount of exhaust due to the formation of bulges in the places of caliber outlets and leads to an increase in the thickness of the layer after the rolling mill, hindering the growth of plant capacity.

In order to increase the productivity of the installation according to the proposed method, the liner, when rolling in an automatic machine, is given a faceted shape with a number of faces that are multiple to the number of rolls of the rolling roll roller.

The method consists in that the shield sleeve is rolled on the automatic machine into a multi-faceted pipe in a multi-faceted caliber on

multifaceted mandrel. This ensures a uniform distribution of the bulges over the perimeter, which creates the necessary conditions for more uniform deformation during running. Moreover, the number of faces of the rolled sleeve should be a multiple of the number of rolls of the rolling mill. Therefore, for a three-roll rolling mill, the cross-section of the liner should be 3, 6, 9 ... facets, and for a two-roll rolling mill, 4,6,8 ... facets.

The outer and inner tube profiles have the shape of a rounded polyhedron.

The proposed metal deformation scheme significantly reduces the degree of non-uniformity of deformation due to the tangential flow of the metal over the entire perimeter. The amount of metal that is used to fill the outlet zone is significantly reduced, which makes it possible to reduce the gauge ovality and improve the quality of the pipes (reduce riots, undercuts, risks and increase the accuracy of the geometric dimensions).

The gripping of the metal of the liner by the rolls is significantly improved, which allows it to be accelerated by the rollers.

FIG. Figure 1 shows the deformation zone in the cell of the automaton, the cross section; on

FIG. 2 - deformation center of the rolling mill

while rolling a hex pipe 1 three

rolls 2, transverse section.

The round pipe obtained after the rolling mill can be calibrated or reduced.

Claims (1)

Invention Formula The method of producing hot-rolled pipes on a machine with an automatic machine, including flashing the billet into the sleeve, rolling it out at the automatic machine in one pass and running in the co-rotating mill, characterized in multiple to the number of rolls of the rolling Kosovalk mill.