RU2412021C1 - Foamed aluminium sheet production method and line - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to powder metallurgy, namely, to production of foamed aluminium sheets and may be used in various branches of machine building. Proposed method comprises charging powder mix into shell, its heating, hot compaction of billet, cutting compacted billet into sheet billets, arranging said sheet billets into mould and subsequent high-temperature treatment. Note here that prior to hot compaction, powder mix is pre-compacted inside the shell with ratio between compaction source arc length and compacted billet thickness exceeding 1.5 by amount exceeding by 10%, and more, its thickness. Proposed line comprises powder mix charging section, powder mix feed section, continuous heating furnace, pre-compaction mechanism, hot-compaction stand, transverse cutting shears, section to feed sheet billets into furnace and furnace to foam sheet billers.

EFFECT: higher quality, reduced power consumption, increased sizes of foamed aluminium sheets.

4 cl, 3 dwg

Description

The invention relates to powder metallurgy and can be used in the manufacture of materials in the form of foam plates of increased length required in mechanical engineering, in particular in such industries as civil and industrial construction, aviation, shipbuilding, nuclear engineering and other industries.

Such materials require a combination of such properties as lightness, buoyancy, high sound insulation, containment of electromagnetic waves, high resistance to corrosion and temperature.

A known method, adopted as an analogue, to obtain porous semi-finished products ("foam") and finished products from powders of aluminum alloys (see, for example, patent RU 2154548 from 2000.08.20), where powders of aluminum alloys are mixed with porophores with a decomposition temperature exceeding solidus-liquidus temperature of aluminum alloy powder. Pour the mixture into a container of aluminum alloy, heat the container with a mixture of powders. Then carry out hot pressing, reheating, hot deformation of the pressed billet, its cooling and subsequent high-temperature processing in the form, re-cooling. The mixture of powders of aluminum alloys with porophores is pre-compacted. Heating the container with a compacted mixture of powders before hot pressing and heating the pressed billet before hot deformation is carried out to a solidus temperature of the lightest component of the aluminum alloy. High-temperature heat treatment is carried out by subjecting the preform to comprehensively uniform heating to a temperature of 40-70 ° C above the solid-liquid phase transition temperature. In addition, according to the second variant of the method, hot deformation of the pressed billet is carried out by rolling, giving it the shape of a sheet, and before high-temperature heat treatment it is heated to 350-450 ° C and maintained at this temperature, followed by shaping the finished product.

In the method, the second option deserves attention, where the pressed preform is subjected to hot rolling before high-temperature foaming treatment.

The known method has the following disadvantages:

- high energy costs due to additional heating;

- orientation to single-piece low-productivity rolling;

- the impossibility of producing plates of foam aluminum of large thickness (50-100 mm and above) and length (as, for example, in the proposed line up to 5000 mm and more).

Known technological line, adopted as an analogue, the production of porous and non-porous metal sheets (patent 10324904 A, B22F 3/18, B22F 3/11, H01M 4/8, from 02.27.1998, Japan), characterized in that it contains hopper with metal powder of vertical design, with horizontal design: belt conveyor, cold rolling mill, foaming heating furnace for cold rolled sheets, conveyor table, hot rolling mill and coiler for winding hot rolled sheets, while the belt conveyor is made receiving etallichesky powder from the hopper flowing along with it through a deformation zone stand cold-rolling and cold-rolled sheet conveying a foaming heating furnace.

The disadvantages of the known line include the presence of relatively high energy costs in the production of thick strips due to the need for very large rolling forces and the low quality of metal bonds both at the points of contact with a clean surface and at the points of contact through a metallized oxide film, due to low efficiency.

The known method and technological line, adopted as a prototype, realizing the production of porous semi-finished products from powders of aluminum alloys (patent RU No. 2200647, B22F 3/11, C22C 1/08, 03/20/2003), which include a powder mixture dispenser, through passage a heating furnace with a conveyor belt passing through it for receiving a cold powder mixture, transporting a heated powder mixture and dispensing a heated powder mixture into a vertical chute equipped with a heating and vibration-compaction powder mixture stroystvami, hopper - wiring and rolling mill of hot compacting of the powder mixture in a horizontal version, scissors transverse cutting to length goryachekompaktirovannoy slab and apparatus for foaming high temperature treatment goryachekompaktirovannoy slab.

The method and line allow hot compaction with sufficiently high deformations, however, the prototype has the following disadvantages:

- uneven mechanical properties across the width of the compacted sheet stock;

- high energy costs due to two heatings, additional heating and compacting of the powder mixture with significant heat transfer to the rolls;

- vertical execution of the technological line, requiring a specialized production building and complicating the combination of reliable process control with ensuring fire safety, as well as the need for protection for environmental cleanliness.

The technical result, which the method and line is aimed at, is to increase the efficiency of hot compacting of the workpiece in the closed caliber of the rolling rolls and, as a result, to the uniformity of the properties of the obtained foam sheets in width and length.

The technical result is achieved by eliminating the slowing down of the movement of granules in the central part of the shell with the powder mixture in the zone preceding the deformation zone ("outburst", according to the book by V.P. Severdenko, N.V. Shepelsky, V.Z. Zhilkin "Pressure treatment of granules of aluminum alloys ". M.," Metallurgy ", 1980, p. 150, 153-154), while prior to hot compacting the rolling stock in the closed caliber of the rolling rolls, pre-compaction of the rolling stock by a value of 10% or more of the thickness, which guarantees at temperament the formation of sintering sites on the granules, as well as with the ratio of the length of the arc of the compaction center to the thickness of the workpiece being compacted, is more than 1.5, which ensures the compaction process over the entire cross section of the workpiece. As a result, the powder mixture becomes still friable, but already monolithic, which ensures the subsequent compacting of the billet in the rolling mill with high compacting efficiency in the deformation zone both in width and in length.

A foam aluminum sheet production line that implements this method, comprising a powder mixture supply device for heating, a continuous heating furnace, a hot compacting stand for a rolled powder mixture, shears for transverse cutting of a compact rolled material into measured lengths of blanks, a discharge roller table and a foaming furnace for sheet blanks, characterized in that it is supplemented by a pre-compaction mechanism installed in front of the hot compaction stand. At the same time, in the production of foam aluminum sheets with a thickness of up to 15-20 mm, the pre-compaction mechanism is made in the form of a sealing stand with a diameter of work rolls of the order of 300 ... 600 mm, and in the production of foam aluminum sheets with a thickness of more than 20 mm, the pre-compaction mechanism is made in the form of a stamp with a return - progressive movement, providing a "step" seal.

Such a design of the foam aluminum sheet production line allows:

- to obtain the uniformity of the mechanical properties and geometric dimensions of the foam sheets in width and length due to an increase in the efficiency of compaction in the deformation zone due to the absence of “back pressure”;

- reduce energy consumption due to the lack of additional heating;

- create conditions for the maximum possible mechanization and automation of the production of foam sheets due to the stabilization of the operation of each line mechanism in time;

- receive panels of sufficiently large dimensions;

- reduce production space due to the completeness of the technological process in one production line from the supply of the powder mixture to obtain the finished product.

The proposed method and line for the production of foam sheets are shown in the drawings, where:

figure 1 shows the production line of foam sheets;

figure 2 shows a diagram of the implementation of the mechanism of pre-sealing by means of a sealing stand;

figure 3 shows a diagram of the implementation of the mechanism of pre-sealing by means of a stamp.

The proposed line of production of foam aluminum sheets, shown in figure 1, contains a plot of filling the powder mixture into a shell made of steel or aluminum alloys 1; a feed-through furnace 2, on which the rolling of the billet from the powder mixture in the shell is heated to a temperature of at least 500 ° C; mechanism for pre-compaction of the rolling stock 3; the hot compacting section of the rolling stock in the closed caliber of the rolling rolls 4; a section for cutting a compacted billet into sheet blanks of measured length 5; a section for placing sheet blanks in mold 6; plot high-temperature processing for the implementation of the process 7.

The work of the proposed line is as follows. In the shell made of steel or aluminum alloys, in section 1, the powder mixture is backfilled. In the continuous furnace 2, the workpiece is heated to a temperature of at least 500 ° C. The pre-sealing mechanism of the rolling stock 3 provides preliminary sealing of the rolling stock by an amount of 10% or more of the thickness, with the ratio of the length of the arc of the focus of the seal to the thickness of the compacted billet more than 1.5. In this case, the mechanism of pre-compaction 3 in the production of foam aluminum sheets with a thickness of up to 15-20 mm, in view of expediency, based on the rational weight of the equipment, is made in the form of a sealing stand, shown in figure 2, with a diameter of work rolls 8 of the order of 300 ... 600 mm pre-compaction of the rolling stock 9, and which includes the traditional composition of the equipment of the working stand, and in the production of foam aluminum sheets with a thickness of more than 20 mm, the pre-compaction mechanism is made in the form of a stamp 10, p shown in figure 3, carrying out the working stroke of the seal during its translational motion with a speed identical to the speed of the rolling stock 9, opening with a return stroke to its original position at a speed an order of magnitude higher than the working one, providing step sealing. Next, the compacted rolling billet is compacted in the closed gauge of the rolling rolls of section 4, followed by cutting into sheet pieces of measured length in the cutting section 5. Sheet blanks of measured length are placed in the mold in section 6 and foamed during high-temperature processing at the liquidus temperature of the powder alloy in section 7.

Thus, the pre-compaction before hot compaction is 10% or more of the thickness with the ratio of the arc length of the compaction center to the thickness of the preform being compacted over 1.5 and the implementation of the proposed method in the production line of foam aluminum sheets in the form of an installation of a preliminary mechanism in front of the hot compaction section of the rolled preform seals with its implementation in the production of foam aluminum sheets with a thickness of up to 15-20 mm in the form of a sealing stand with a diameter of work rolls of the order of 300 ... 600 m And in the production of aluminum foam sheet of a thickness exceeding 20 mm performing it in the form of a slide with reciprocating motion, the step providing a seal, allows:

- improve the quality of foam sheets,

- reduce energy consumption,

- increase the mechanization and automation of the process,

- receive panels of sufficiently large dimensions,

- reduce production space.

Claims (4)

1. A method for the production of foam aluminum sheets, including filling a powder mixture containing a powder alloy into a shell made of steel or aluminum alloy, heating the powder mixture in a shell in a continuous furnace to a temperature of at least 500 ° C, hot compacting the workpiece in a closed caliber of work rolls , cutting a compact rolled billet into sheet billets of measured length, placing sheet billets in a mold and subsequent high-temperature heat treatment at the liquidus temperature of the powder alloy, exl characterized in that prior to hot compaction of the workpiece in the closed caliber of the work rolls, the powder mixture is pre-compacted in the shell with a ratio of the length of the arc of the focus of the seal to the thickness of the compacted workpiece more than 1.5 by a value of 10% or more of its thickness. 2. The production line for implementing the method according to claim 1, comprising a portion for filling the powder mixture into the shell, a device for supplying the powder mixture in the shell for heating, a continuous heating furnace, a mechanism for pre-compaction of the powder mixture in the shell, a hot compaction crate for the workpiece, compact shears for transverse cutting rolling blanks on sheet blanks of measured length, a section for placing sheet blanks in a mold, and a furnace for foaming sheet blanks. 3. The production line according to claim 2, characterized in that for the production of foam aluminum sheets with a thickness of up to 15-20 mm, the preliminary sealing mechanism is made in the form of a sealing stand with a diameter of work rolls of 300 ... 600 mm. 4. The production line according to claim 2, characterized in that for the production of foam aluminum sheets with a thickness of more than 20 mm, the pre-compaction mechanism is made in the form of a press stamp installed with the possibility of reciprocating motion.

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