RU2093288C1 - Rolled sheet production method - Google Patents

Abstract

FIELD: machine engineering, namely manufacture of blanks for rolling sheets and bars. SUBSTANCE: method comprises steps of heating hollow blank, flattening it and separating to sheets by cutting solid bridges; using waste steel tubes as hollow blanks. Hydraulic insulation coat and deposition of said steel tubes are preliminarily stripped at heating tubes until 550-700 C and mechanically descaling them. EFFECT: enhanced degree of metal economy. 2 cl, 2 dwg

Description

 The invention relates to the field of engineering and can be used to obtain blanks for the production of sheet and long products.

 A known method of producing rolled steel [1] including the processing of iron ore in melting furnaces, continuous casting of the resulting steel. Then the ingot is cut into billets of measured length with subsequent rolling on mills. The raw materials are iron and steel scrap, the process is based on the metallurgical method of steel smelting, which greatly complicates and increases the cost of the process of obtaining steel products from recycled materials.

 The closest technical solution is the method of obtaining products [2] from ingots, in which the shell is cut along the generatrix lying in a plane perpendicular to the direction of bending. The jumpers remaining in the notch under the action of a bending moment act as a plastic hinge and provide unhindered extension of the formed half rings. The final separation is carried out after bending. In this case, two products are obtained. The raw materials are large forgings and the shells obtained from them by rolling. But this method can not be obtained from used pipes and other used shells, since they require additional processing to clean the metal from deposits of any kind and kind.

 The present invention solves the problem of simplifying and reducing the cost of the process of obtaining sheet metal by using used steel pipes as the starting material.

The essence of the invention lies in the fact that in the known method of producing blanks for the production of sheet metal, including the heat treatment of a hollow billet, pressing it until completely flattened and cutting the ends of the billet to obtain two flat sheets, according to the invention, the former used as raw materials for producing hollow billets used steel pipes that are cleaned from the old waterproofing coating and deposits by heating to 550-700 ^o C followed by cutting to pipe zag by forging and descaling them mechanically.

 In FIG. 1 shows the source pipe; in FIG. 2 pipe after flattening.

The method is as follows. Depending on the length of the furnaces for heating and burning insulation, choose the length of the pipe whip (up to 19-27 m), which is heated to 550-700 ^o C depending on the properties of the pipe steel [3] According to experiments and operation below 550 ^o C there is a decrease in the qualitative characteristics of the metal, steel embrittlement takes place, therefore, it is impossible to keep the temperature below 550 ^o C. At temperatures from 550 to 700 ^o C there is a vacation, internal stresses in the metal are removed, while the properties of steel are improved. Above 727 ^o C there are quenching processes that can degrade the metal structure, therefore heating above 700 ^o C is undesirable for any grade of pipe steel. When heat treated at temperatures of 550-700 ^o C, the ductility of the metal and corrosion resistance increase, as well as the old insulation and paraffin-resinous deposits completely burn without the formation of unnecessary liquid smudges, and there is a partial detachment of the cinders and seal products from the metal surface.

The temperature limits of 550-700 ^o C are optimal for all types of pipe steels, but due to differences in the structure and properties of the used metal, as well as different deposits, individual studies of heat treatment processes are necessary for each type.

 Pipe lashes, cleaned from insulation, are cut by gas cutting into pipe blanks of the required length. The outer and inner surfaces of the tube billets, depending on the required degree of surface cleanliness, are cleaned of scale, insulation residues and slag inclusions by mechanical means, for example by tapping with a vibration hammer, sandblasting, etc. then the workpiece is flattened using a press and get a double sheet.

где D внутренний диаметр трубной заготовки;
δ толщина стенки трубной заготовки.The width of the double sheet is determined by the formula

where D is the inner diameter of the tube stock;
δ wall thickness of the tube billet.

 To obtain sheet metal, rounding and ends of double sheets are cut, and two sheets of rolled metal of a given size are made of stainless steel, bypassing the metallurgical process, steel smelting and rolling.

 The resulting material can be used in the construction, installation, reconstruction, operation of almost any large and small objects, for the manufacture of all kinds of frames, trusses, beams, floorings, flat and three-dimensional structures, where large quantities are consumed of structural sheet and steel, whose resources are limited .

 Tests of the method for producing sheet metal from pipes that were used at the Salavatneftemash NPO (Salavat) showed the feasibility of the method for producing sheet metal from used pipes, bypassing the metallurgical process. The properties of the rolled products corresponded to the Gost quality indicators of the original pipes; no deterioration in the properties of steel occurred.

 Provided that the process of heat treatment and utilization of combustion products is developed for each type of used pipe, the method can be widely used in the national economy.

Sources of information
1. Technology of metals and materials science / Ed. L.F. Mustache. M. Metallurgy, 1987, p. 31.

 2. A.S. USSR N 1344482, class B 21 C 5/00, publ. 10/15/87.

 3. Gulyaev L.P. Metallurgy. M. Metallurgy, 1977, p. 285, 271.

Claims (2)

1. A method of producing sheet metal, including heating a hollow billet, flattening it and dividing it into sheets by trimming solid bridges, characterized in that used steel pipes are used as a hollow billet, from which the waterproofing coating and deposits are previously removed by heating to 550,700 ^o C and subject them to descaling mechanically.  2. The method of claim 1, characterized in that before the flattening of the pipe is cut into pieces of the required length.

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