EP0237008A1 - Device for the continuous casting of quickly solidifying materials - Google Patents

Abstract

In the melt spinning process for the production of metal foils with an amorphous structure by casting molten metal through a slot-like nozzle (13) onto a wall (14) which moves quickly past the nozzle, a particularly rapid quenching and cooling rate of the solidifying melt is achieved by Nozzle (13) opposite side of the wall (14) with cooling pressure medium supplied with cooling support elements (17¹) are provided. The wall is advantageously designed as a thin-walled, somewhat elastically deformable cylinder shell (14), in the interior of which several rows of cooling support elements (17¹-17⁸) are provided, which are controlled by thickness and temperature profile sensors (25, 27, 29) can. This enables continuous production of amorphous metal foils.

Description

The invention relates to a device for the continuous casting of rapidly solidifying material, the liquid, hot material flowing through a slot-like nozzle onto a cooled wall of good heat-conducting material that is moving close to the nozzle, solidifying on this wall, and after a certain distance from it Wall is detached.

Such devices are known for example from US 4 142 571 or EP 2 785. They use a process known, for example, from the "Zeitschrift für Metallkunde", volume 64 (1973), pages 835-843, under the name "Melt Spin Process", which in turn is inspired by Sir Henry Bessemer and EH Strange and CA Pim are based.

Such a method is particularly suitable for the production of foils from metals or alloys, optionally with additions of fine, non-metallic particles, with extremely fine-grained or amorphous, glass-like structure, which can be achieved with conventional casting methods driving is not reachable. In order to achieve this structure and the associated new material properties, it is necessary that the melt solidifies on the moving cold wall extremely quickly, ie with an extremely high cooling rate of at least 10⁴, preferably of the order of 10⁶ ° C / sec, before the solidified film is detached from the cooled surface with a suitable device or by centrifugal force and is guided away for further use.

Because of the high incidence of heat on the moving wall, the first melt spinning devices that became known were only suitable for discontinuous operation, in which the heat capacity of the wall is sufficient to absorb the heat quantity of a batch produced. So that the heat generated can be easily absorbed by the wall, it was made of a good heat-conducting material, preferably copper or an alloy, e.g. Beryllium / copper made.

In order to maintain continuous operation, however, it would be necessary to cool the moving wall as well as possible. When cooling by means of gas streams blown onto the wall surface, however, only a small amount of heat can be removed. Cooling by means of water or other liquids on the wall surface on which the melt solidifies, however, easily leads to contamination of the surface, which impedes the casting process or even makes it impossible. In addition, the cooling was adjustable or varied across the width of the moving wall was neither possible nor recognized as desirable.

Another problem that arises during the production, in particular of wide films, is the constant thickness of the films produced. Experience has shown that the edges of thinner foils tend to thicken. In the case of previously known devices, attempts have been made to achieve a uniform thickness by adhering to certain gap dimensions and distances of the gap from the moving wall. However, it was not possible to correct deviations in film thickness and to comply with prescribed target values in a continuously working process.

From EP 8901 (= US 4 193 440) and FR 2 307 599 (= US 4 061 178 and 4 190 103) strip casting devices for low-melting metals are known, in which the melt is introduced into the gap between two water-cooled metal strips. The two belts are pressed against one another by pairs of cooling support elements in the running direction only at a certain distance after the point of addition of the melt. However, the cooling rate of the melt is not sufficient for the formation of a metal foil with an amorphous structure.

From EP 41 277 (= US 4,434,836) a casting method is also known in which molten metal is poured into a groove on the inside of a metal cylinder, which follows at a certain distance the addition point is cooled from the outside by means of cooling water nozzles. Here, too, the cooling rate is not sufficient to produce an amorphous structure. Thickness regulation is not provided at all.

Finally, US Pat. No. 3,712,366 describes a metal casting process in which the melt solidifies on the outer surface of a cylinder, which is cooled by water which is thrown uniformly onto the entire inside by means of centrifugal force. The cooling rate that can be achieved in this way is also insufficient for the formation of amorphous metal structures. No thickness control is disclosed here either.

In the continuous casting process described in FR 2 347 999 (= US 4 091 862), the molten metal is passed between two guide plates, which are cooled from the outside with cooling support elements. The rate of solidification is not sufficient in this process either.

The invention sets itself the task of eliminating the above-mentioned disadvantages of the prior art and, in particular, developing a device for the continuous casting of rapidly solidifying material on a moving wall during continuous operation in such a way that the cooling is more intensive and sufficiently large for casting amorphous metal foils and the film speed can be increased that cooling across the width of the web is adjustable and at the same time film thickness deviations from a setpoint can be compensated.

According to the invention, this object is achieved in that the wall is designed to be elastically yielding to a certain degree and is cooled directly opposite the nozzle on the side facing away from the nozzle by means of at least one cooling support element which is movable in a support direction perpendicular to the wall and which has at least one with the wall Cooling pressure medium supplied storage area and is supported on a fixed crossbar. The cooling support element arrangement directly on the opposite side of the wall at the same place where the melt is applied, results in particularly intensive cooling and an extremely high cooling rate.

The cooling support elements are advantageously supported on the crossmember by means of a pressure chamber supplied with cooling pressure medium and have pressure pockets on their bearing surface which are connected to the pressure chamber via bores, as a result of which coolant is concentrated directly on the point where the melt is applied.

It is advantageous to arrange a plurality of cooling support elements next to one another transversely to the direction of movement of the wall on its side facing away from the nozzle, said cooling support elements being individually movable perpendicularly to the wall in the support direction. These side by side cooling support elements can control separately from each other with cooling pressure medium baren pressure can be supplied, or via a common pressure line and a controllable throttle valve belonging to each element. In the case of an elastically resilient wall, not only is the cooling effect on the individual cooling support elements variable, but also, due to the slight deformation of the wall, the distance to the nozzle and thus also the outflowing mass and the local film thickness, or the thickness profile of the film.

A preferred embodiment is particularly advantageous in terms of construction, in which the elastically flexible wall is designed as a relatively thin-walled cylinder shell which is held on both sides by end disks and is rotatably mounted on the fixed crossmember. For this purpose, seals are also provided which seal the inside of the cylinder shell from the bearing and the bearing from the outside world, as well as a suitable drive for the cylinder shell. Since the end disks cause a certain local stiffening of the cylinder shell, the usable working width, i.e. the film width is slightly less than the total roll width.

In order to achieve particularly intensive cooling, it is advantageous to provide a plurality of rows of cooling support elements in the interior of the cylinder shell which are oriented in the axial direction. The best possible cooling is achieved if the rows of cooling support elements are provided distributed over the entire inner circumference of the cylinder shell.

The arrangement of several cooling support elements transversely to the material web movement next to one another with separate control allows the cooling and the distance from the nozzle to be regulated by controlling the coolant pressure in the individual elements by means of suitable thickness sensors which continuously record the film thickness profile at the film outlet and via a suitable control device or a computer Deliver control signals for the coolant pressure. In addition, temperature sensors can be provided transversely to the web, which control another row of cooling support elements, so that a desired temperature profile is created.

• Figur 1 eine Vorrichtung in Perspektive,
• Figur 2 einen Querschnitt durch eine andere Vorrich­tung, und
• Figur 3 einen Längsschnitt durch die Vorrichtung nach­Figur 2.

The invention is explained in more detail using the exemplary embodiments shown in the figures. Show it:

• 1 shows a device in perspective,
• Figure 2 shows a cross section through another device, and
• FIG. 3 shows a longitudinal section through the device according to FIG. 2.

In the device shown in FIG. 1, molten metal is fed to a container 1, in which it is heated by means of a high-frequency induction coil 2 approximately 100 ° above the melting temperature of the metal. The hot, liquid metal flows through a, possibly under a certain pressure slot-shaped nozzle 3 onto a cooled wall 4, which moves rapidly transversely to the slot direction. On the top of this wall 4, the molten metal is quenched and solidifies into a thin band 5, which is removed from the wall 4 after a certain cooling distance. In order to produce an amorphous or extremely fine-grained metal foil 5, the nozzle 3 is to be designed in a known manner, for example with a slot width of a few tenths of a millimeter and at a distance of a few tenths of a millimeter from the wall 4. With a movement speed of the wall in the range of 2 - 50 m / sec, for example of 10 - 20 m / sec, foils with a thickness in the range of about 20 - 50 micrometers can be produced in a width from the decimeter to the meter range.

In the illustrated embodiment, the wall 4 is designed as an endless belt guided over two rollers 6 1 and 6 2. This band 4 is made of a material and with such a wall thickness that it is deformed in the elastic region during circulation. In addition, it is selected so that it has the best possible thermal conductivity. When processing aluminum or alloys with a melting point in the range of 1100 ° C., for example, copper or a copper-beryllium alloy in particular has proven to be a suitable material for the strip 4. When processing materials with higher melting points, a suitable, different material must be selected for the material of the band 4.

The quenching or cooling rate of the melt is decisive for the production of an amorphous structure in the metal phase or even an extremely fine crystalline structure. An amorphous structure can usually only be achieved if this cooling rate is at least 10 ° C / sec. In order to achieve this extremely high cooling rate, a hydrostatic cooling support element 7 1 is provided directly opposite the nozzle on the side of the strip 4 facing away from the nozzle 3, and a further cooling support element 7 2 is provided behind the strip 4 to improve the cooling effect in the running direction. These cooling support elements 7 1 and 7 2 are on pressure spaces 8 1 and 8 2 which are connected via lines 9 1 and 9 2 with a coolant under pressure, e.g. Water, optionally with suitable additives, are supported in a cross member 10 which projects transversely through the band 4. On their underside of the band 4 side, the cooling support elements 7¹ and 7² are provided with hydrostatic bearing surfaces which are connected to the pressure chambers 8¹ and 8² by bores and pass cooling pressure medium to the underside of the band 4 via these. It is expedient to keep the escaping coolant away from the top of the belt by taking suitable precautions.

Since the coolant acts on the band 4 made of a good heat-conducting material directly at the point at which the hot molten metal is applied to the band 4 and the cooling effect is continuously continued in the running direction of the band 4, the device described is a continuous melt spinning process become possible with a significantly increased cooling rate with a value above 10 ° C / sec. With this device, a series of alloys of the elements iron, nickel, cobalt, aluminum, molybdenum, chromium, vanadium, boron, phosphorus, silicon and other foils up to approx. 20 - 50 micrometers thick with a completely amorphous structure and unusual properties could be produced, in a continuous process. The film thickness can be controlled by the coolant pressure and the variable distance of the band 4 from the nozzle 3.

FIGS. 2 and 3 show a particularly advantageous, preferred embodiment of a melt spinning device in which the wall rapidly moving past the slot-like nozzle 13 of the container containing the molten metal is designed as a rapidly rotating cylinder tube 14. The diameter of the cylinder tube 14 can be selected in the order of a few decimeters and its rotational speed can be in the order of up to approximately 50 revolutions per second, so that a movement speed of up to approximately 30 m / sec results. A particularly good heat-conducting metal is selected as the material of the cylinder shell 14, for example copper or a copper alloy, and its thickness is, for example, in the range of a few millimeters, so that a certain elastic deformability is given.

In the interior of the cylinder shell 14, a fixed cross member 20 is provided, on which in the direction of rotation tion several rows of cooling support elements 17¹ - 17⁸ are supported on corresponding pressure chambers 18. On the inside of the cylinder shell 14 side, the cooling support elements, as shown in the example of the first element 17¹, are provided with hydrostatic bearing pockets 16, which are connected to the pressure chamber 18 via throttle bores 12, which in turn are connected to a cooling pressure fluid by coolant lines 19 the traverse 20 are supplied from. Via these coolant lines 19, the pressure chambers 18, the throttle bores 12 and the bearing pockets 16, the coolant reaches the inside of the cylinder shell 14 and ensures constant cooling and heat dissipation, so that an extraordinarily high quenching and cooling rate also occurs here in a continuous process of the metal layer 15 applied to the surface of the cylinder shell 14. Since the entire inner circumference of the cylinder shell 4 can be provided with cooling support elements, the cooling effect is even more intensive here, so that the desired amorphous structure of the metal foil formed can be achieved with even greater certainty.

In the coolant supply lines 19 for the individual cooling support elements 17¹ - 17⁸ controllable valves 21¹ - 21⁸ are provided, with which the amount of the coolant supplied to the individual cooling support elements or its pressure can be regulated.

As shown particularly in Figure 3, the individual rows of cooling support elements 17¹ -17⁸ from several axially closely spaced, individually controllable support elements can be formed, as is shown, for example, by means of the upper support element row 17¹¹, 17¹², 17¹³ ... and the opposite row 17⁵¹, 17⁵², 17⁵³ ....

The ends of the cylinder shell are provided with end disks 22 which seal the inside of the cylinder from the outside world and are rotatably supported on the ends of the cross member 20 by means of suitable roller bearings 23 and are provided with a drive (not shown). The end disks 22 prevent coolant from escaping from the interior of the cylinder shell, so that the coolant cannot get to the outside and the metal foil formed, where it could give rise to undesirable reactions. Instead, the excess coolant is safely drained off through suitable holes in the crossmember. Otherwise, the solidification process can take place on the outside of the cylinder shell in an inert gas atmosphere.

The provision of several cooling support elements 17¹¹, 17¹², 17¹³ ... in the axial direction next to each other on the opposite side of the cylinder shell 14 to the slot-like nozzle 13 also allows automatic control of the thickness of the metal foil produced over the entire width in a particularly favorable further developed embodiment, which is particularly the case with the production of wide metal foils is important.

For this purpose, as shown in FIG. 2, after the film run-off, which can be done, for example, by means of a scraper 24 or an air nozzle, thickness sensors 25 are provided distributed over the width of the film produced. These thickness sensors 25 are connected to a control device 26, which controls the valves 21¹, 21³, 21⁵ and 21⁷ with appropriate control signals, for example with the aid of a suitably programmed microprocessor. The control device 26 or its program is set up so that when the film thickness measured by the thickness sensors 25 increases, the valves 21¹ and 21⁵ of the corresponding cooling support elements 17¹ and 17⁵ are opened somewhat at the corresponding point on the axis, so that a larger amount of pressure medium is supplied to the two cooling support elements 17¹ and 17⁵. At the same time, the valves 21³ and 21⁷ of the cooling support elements 17³ and 17⁷ arranged perpendicular thereto are throttled somewhat, so that the pressure of the coolant in these support elements decreases somewhat. As a result, the cylinder shell 14 is deformed a little bit elliptically, so that the gap between the cylinder shell 14 and the slit-like nozzle 13 is reduced somewhat at the point in question and less metal melt escapes at this point, so that the film thickness is automatically regulated to the predetermined desired value . The fact that two opposing cooling support elements are influenced in the same way eliminates the integral bending stresses of the cylinder shell, so that no forces are released that would have to be conducted via the side bearings. The design effort can be reduced by always having two opposing cooling support elements are fed via a common valve.

Since further rows 17², 17⁴, 17⁶ and 17⁸ are recommended to achieve very intensive cooling in addition to the four rows of cooling support elements mentioned, for example in the region of the bisector to the above-described axis cross, these additional rows of cooling support elements can be used to effect temperature regulation By a temperature sensor system 27 detects the temperature profile across the film width, it feeds it to a second control device 28, which in turn can be equipped with a suitable microprocessor, which in turn directs control pulses to the throttle valves 21², 21⁴, 21⁶ and 21⁸ of the corresponding cooling support elements, in the sense that e.g. more cooling liquid is supplied to the cooling support elements at the point of an elevated temperature and correspondingly less at points with a low temperature. Here, too, the structurally simplified circuit can be selected to control these cooling support elements in each longitudinal plane via a common valve. In addition, further elements can be provided in the circumferential direction, in the gaps between the said cooling support elements 17¹ - 17⁸, which are controlled with a suitable coolant pressure.

Depending on the type of film to be produced, it is important that the temperature profile of the moving wall is sufficiently balanced before entering the area of the slot-like nozzle 13. At this point, therefore a further temperature profile sensor system 29 can be provided, which also supplies the second control device 28 with corresponding signals. In this case, the program of the control device 28 is expediently selected such that a signal which is suitably weighted from the two measurement information items, depending on the product, serves as a control signal.

Claims (12)

1. Device for the continuous pouring of rapidly solidifying material, the liquid, hot material flowing through a slit-like nozzle (3, 13) onto a cooled wall (4, 14) of good heat-conducting material that is moved close to the nozzle (4, 14) solidifies and is detached from the wall after a certain distance, characterized in that the wall - (4, 14) is designed to be elastically flexible to a certain degree and directly opposite the nozzle (3, 13) on that of the nozzle (3, 13) opposite side is cooled by means of at least one cooling support element (7¹, 7²; 17¹ - 17⁸) which is movable in a support direction perpendicular to the wall (4, 14) and which is provided with at least one bearing surface (16 ) and is supported on a fixed crossmember (10, 20). 2. Device according to claim 1, characterized in that in addition to the on which the nozzle (3, 13), opposite side of the wall (4, 14) arranged cooling supporting elements (7¹, 17¹) in the direction of movement of the wall (4, 14) in addition to these at least another cooling support element (7², 17² - 17⁸) is arranged. 3. Device according to claim 1 or 2, characterized in that transverse to the direction of movement of the wall (4, 14) each have a plurality of cooling supports elements (17¹¹, 17¹² ..., 17⁵¹, 17⁵² ...) are arranged, which are independently supplied with cooling pressure medium. 4. Device according to one of claims 1-3, characterized in that the cooling support elements (7¹, 7²; 17¹ - 17⁸) each on a pressure chamber supplied with cooling pressure medium (8¹, 8²; 18) on the fixed crossmember (10, 20) are supported and each have at least one pressure pocket (16) on their bearing surface, which is connected to the pressure chamber (18) by a bore (12). Valve (21¹ - 21⁸) 5. Apparatus according to claim 4, characterized in that in the pressure medium supply lines (19) each have a controllable for the pressure chambers (18) is provided. 6. Device according to one of claims 1-5, characterized in that thickness sensors (25) for detecting the local value of the thickness of the film (5, 15) are provided over its width, and a control device controlled by the thickness sensors (25) (26), which is set up to regulate the pressure of the cooling pressure medium for the cooling support elements (7¹, 17¹) which are arranged on the side of the wall (4, 14) opposite the slot (3, 13), and thus one Deformation of the resilient wall (4, 14) and thus a change in the amount of material flowing out of the nozzle (3, 13) to cause. 7. Apparatus according to claim 6, characterized in that temperature sensors (27) are provided for detecting the temperature profile across the width of the web produced, and a further control device (28) which supply a cooling pressure medium to other cooling supporting elements (17², 17⁴, 17⁶ , 17⁸) regulates. 8. The device according to claim 7, characterized in that a further temperature profile sensor system (29) is provided, which detects the temperature profile of the moving wall (4, 14) across its width in front of the region of the nozzle (3, 13) and signals the further control device (28) emits, which forms a weighted signal for the supply of cooling pressure medium from the signals of both temperature sensor systems. 9. Device according to one of claims 1-8, characterized in that the wall (14) is designed as a thin-walled cylinder shell, which in its interior several rows distributed over the circumference of against a central cross member (20) supported cooling support elements (17¹ - 17⁸ ) having. 10. The device according to claim 9, characterized in that the cylinder shell (14) is sealed on both sides by end plates (22) against the outside atmosphere, the end plates (22) by means of bearings (23) on the crossmember (20) are rotatably mounted . 11. Apparatus according to claim 8 and 9, characterized in that the thickness sensors (25) the pressure of the cooling pressure medium in oppositely disposed rows of cooling supporting elements (17¹, 17⁵, 17³, 17⁷) control in the same way, the pressure right at an angle twisted cooling support elements, however, in the opposite sense, so that the cylinder shell (14) is deformed elliptically. 12. The apparatus of claim 7 and 11, characterized in that the temperature profile sensors (27) driven cooling supporting elements (17², 17⁴, 17⁶, 17⁸) in the region of the bisector of the driven by the thickness sensors (25) cooling supporting elements (17¹ , 17³, 17⁵, 17⁷) axis cross are arranged.

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