RU2527547C2 - Production of unrestrictedly long bar from distilled calcium - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed process comprises loading calcium into mould container and compaction with welding of loaded calcium. Uniform mechanical properties without localised arc zone at whatever section of finished article are ensured by loading said calcium in said container of arbitrary shape and size with pre-compaction by crush seal, pressing at the rate of not over 5 mm/s with welding of consecutively loaded portions with press residue height not exceeding 0.2 diameter of the container. To facilitate ductility of finished bar, tool may be heated to 0.45 of calcium melting point, not over.

EFFECT: higher ductility of bar.

3 cl, 3 ex

Description

The invention relates to the processing of metals by pressure, and in particular to the manufacture of a continuous calcium bar by pressing.

Calcium and its alloys are needed in significant volumes for desulfurization, deoxidation of steels and cast irons, alloying of non-ferrous metal alloys. Currently, the most widespread method is the introduction of calcium and its composites with other substances into molten metals and alloys in the form of a wire or rod in a steel shell.

A known method of producing filler material with calcium in the form of a wire, consisting of a steel shell and a core of powdered silicocalcium or calcium carbide, granular calcium or granules of calcium alloys with aluminum, silicon, magnesium and other materials, which are first compacted and compacted, and then pressed or rolled in capsules (US Pat. No. 4,671,820). This method of manufacturing a shell wire with granular calcium filler involves preliminary mechanical grinding of distilled calcium to a powder of a certain fraction or granulation of the original distilled calcium from a metal melt, which significantly affects the yield of the product and the cost of manufacturing the shell wire.

There is a method of producing a composite wire of calcium in an aluminum sheath. Calcium is enclosed in an aluminum shell and extrusion (pressing) get a bar stock. The final product is obtained by subsequent repeated cold deformation by drawing the intermediate workpiece in an aluminum shell (patent SU 1807618).

Known two-stage method (patents RU No. 20111685) of obtaining products from calcium distilled in the form of a wire, which can be used to obtain a sheathed wire. According to this method, distilled calcium in a compact form with an uncast crystalline structure and a developed surface is used as a starting material. In a first step, distilled calcium is first heated and then pressed to form intermediate stocks in the form of a bar. Measured billets for the second stage of pressing are made from a bar. The final product in the form of a wire is made by extrusion from measured billets after their preliminary heating.

Closest to the claimed invention is a method for producing articles of calcium distilled in the form of a wire of the Russian Federation No. 2152834. In this method, the starting material for the calcium wire is compact distilled calcium in the form of cylindrical blanks. The method of producing wire involves the use of two stages of pressing and includes the first heating, the first stage of pressing distilled calcium to obtain intermediate preforms, the second heating and the second stage of pressing in continuous mode with welding of sequentially supplied intermediate preforms. Before the first heating, the outer surface of the distilled calcium preforms is first cleaned of oxides and contaminants, then it is heated in an atmosphere of air to a temperature of not more than 0.12 of the melting point of calcium. The second heating before pressing the wire is carried out in air to a temperature of not more than 0.18 melting points of calcium. Cleaning the outer surface of distilled calcium before the first heating, limiting the heating temperatures of the workpieces at the first and second stages is carried out to increase the mechanical characteristics of the wire in the sections corresponding to the weld zone and expand its range by making wires with a diameter of less than 10 mm. This wire can be used for the manufacture of sheathed wire.

Considering this method of producing continuous calcium wire, we note that the process of obtaining the finished product from compact distilled calcium is multi-stage, energy-intensive, time-consuming and requires a large number of pieces of equipment. Distilled calcium has a loose crystalline structure with a developed surface and, when heated in air, inevitably undergoes oxidation. In addition, preheating of the starting material in an atmosphere of air leads to significant metal losses during pressing in the first stage, because press residue from metal and oxides requires subsequent removal, disposal and processing. The production of measured billets from the bar after the first pressing also requires the disposal and processing of chips. The pressing of measured intermediate blanks at the second stage occurs with the formation of a localized welding zone, the mechanical properties of which differ from the properties of the metal. The formation of a localized zone is due to the fact that the intermediate blanks obtained by pressing in the first stage have a deeply deformed structure approaching a cast one, especially at the interface. In addition, when heated in air, calcium activity at the interface decreases and a weld zone is formed in the product, which has a reduced strength.

The aim of the invention is to obtain a product in the form of a bar of unlimited length distilled from calcium with high mechanical properties, in one stage of pressing, using a minimum amount of equipment, reducing energy costs, the complexity of the process and minimizing waste requiring additional processing and disposal.

The technical result is achieved by the fact that distilled calcium of arbitrary shape is used as a starting material, it is loaded without preliminary heating into a press container onto a press residue with a height of at least 0.2 container diameters and pressed at a speed of not more than 5 mm / s. The thermophysical properties, ductility and weldability of active distilled calcium with a press-limited size residue during the pressing process exclude the appearance of a localized welding zone (weld). In the inventive method, there is no need to preliminarily grind distilled calcium to a powder state by a mechanical method or by granulation of a molten metal, it is not necessary to manufacture intermediate measured billets, therefore, when implementing the proposed method, the smallest possible number of units of equipment is used, energy costs are reduced by an order of magnitude, and the process complexity is reduced. The proposed method allows the use of preforms prefabricated by compaction of the source of lumpy distilled calcium by any of the known methods of deformation compaction of the source material with deformation that ensures minimal adhesion of individual pieces to each other. Under the claimed conditions, it is not necessary to heat distilled calcium before pressing, which prevents oxidation of the wrought material and a decrease in its activity, thereby minimizing the amount and type of waste requiring utilization and processing. At the same time, since preliminary heating of calcium before pressing is not carried out, the process can be stopped at any time without removing the press residue, and then pressing with welding into a continuous bar can be continued by loading another portion of pieces of distilled calcium.

The inventive method has been successfully tested, products were obtained in the form of an unlimited length of a rod of distilled calcium with a diameter of 8 to 14 mm and a length of over 2000 meters each. From the obtained calcium rod is made of a sheathed wire in an iron shell.

Example 1

The method was tested on a vertical hydraulic press with a force of 15MN. Tool: single-channel dies with a round hole with a diameter of 8 mm, 9 mm and 14 mm and a pressing container with a diameter of 110 mm, 130 mm and 150 mm. Pieces of distilled calcium of arbitrary shape and size from 1 to 130 mm without preliminary heating were loaded into a container with a diameter of 130 mm and pressed at a speed of not more than 5.0 mm / s with hoods (µ) equal to 264, 210 and 80 for a bar with a diameter of 8 mm , 9 mm and 14 mm, respectively. Pressing from a 110 mm container was carried out with µ = 180, µ = 150, and µ = 60 for a bar with a diameter of 8 mm, 9 mm, and 14 mm, respectively. From a container with a diameter of 150 mm, pressing was performed with μ = 351 for a bar with a diameter of 8 mm.

A continuous bar was obtained by deformational welding of the press residue with the next portion of the loaded pieces of distilled calcium. The absence of a weld or a localized welded zone was ensured by the use of a limited pressing residue, the height of which corresponded to at least 0.2 diameter of the container for pressing. Reducing the height of the press residue led to the appearance of defects on the finished product in the form of cracks, tears, sinks, etc., which reduce the manufacturability of manufacturing a continuous wire rod from a continuous wire. The high initial calcium activity, the structure of the starting material, together with the deformation heating and speed limitation during pressing, provided uniform mechanical properties along the entire length of the finished bar.

Since there is no need for regulated heating of calcium before pressing, the process could be stopped for a long time, and then continue after loading the next portion of pieces of distilled calcium.

Example 2

The testing of the method according to example 1, but during pressing a single-channel matrix and a container for pressing with a diameter of 130 mm and 150 mm were subjected to constant heating to a temperature of not more than 350 ° C. Constant limited heating of the tool and deformational heating of calcium provided high ductility of the finished bar with a diameter of 8 to 14 mm, which is necessary for the high-quality formation of the sheathed wire. Tests of mechanical properties along the length of the bar showed that the yield strength (σ ₂ ) of at least 45 MPa, the elongation (δ) of at least 10%.

Example 3

The method was tested according to examples 1 and 2, but distilled calcium was pressed in the form of preforms with a diameter of up to 130 mm obtained by preliminary compaction of pieces of arbitrary shape and size from 1 to 100 mm. In this case, they solved the problem of maximizing the use of the useful volume of the container for pressing and reducing the complexity of the loading process. Compaction was carried out at room temperature in a collapsible container of cylindrical shape. The pieces were loaded into a container, after which an intermediate blank with a structure providing a minimum adhesion of individual pieces, which corresponded to a decrease in the bulk volume by about 25%, was formed on the pneumatic hammer by deformation sealing. The obtained intermediate preforms were pressed without preliminary heating at a speed of not more than 5.0 mm / s.

Claims (3)

1. A method of producing an unlimited length of a bar of distilled calcium, comprising pressing and welding of a calcium press sequentially loaded into a container, characterized in that the distilled calcium is loaded into a press container with pieces of arbitrary shape onto a press residue with a height of at least 0.2 container diameters, and pressing produce at a speed of not more than 5 mm / s. 2. The method according to claim 1, characterized in that the matrix and the press container are heated to a temperature of not more than 0.45 melting point of calcium. 3. The method according to claim 1 or 2, characterized in that before pressing the pieces of distilled calcium are compacted by means of a deformation seal.