CONTINUOUS CASTING MOULD

Abstract

The mould contains a casting wheel, on the outer surface of which an open channel is made, a continuous tape adjacent to the casting wheel from its outer surface in such a way as to close the specified open channel, as well as a cooling system able of adjustable supply of coolant to the casting wheel and the continuous tape at least on the outer surface, on the inner surface and on both side surfaces of the wheel, in which the ratio of the coolant flow on the inner surface of the wheel to the coolant flow on the outer surface of the wheel is 1.9-3.0, and the ratio of the total coolant flow on the side surfaces of the casting wheel to the coolant flow on the inner surface of the casting wheel is 1.3-1.7.

Claims

1. Continuous casting mould (1) containing: a casting wheel (6), on the outer surface (15) of which an open channel is made, having a cross-section in the form of an isosceles trapezoid, and the ratio of the length of the large base (19) of the trapezoid to the length of the small base (20) of the trapezoid is in the range of 1.3-1.6; a continuous belt (4) adjacent to the casting wheel (6) on the side of its outer surface (15) in such a way as to close the specified open channel; a cooling system made with the possibility of adjustable supply of coolant to the casting wheel (6) and the continuous belt (4) located at least on the side of the outer surface (15), the inner surface (17) and both side surfaces (16) of the wheel (6), and the ratio of the coolant flow on the side of the inner surface (17) of the wheel to the coolant flow on the side of the outer surface (15) of the wheel (6) is 1.9-3.0, and the ratio of the total coolant flow on the side of the side surfaces (16) of the casting wheel (6) to the coolant flow on the side of the inner surface (15) of the casting wheel (6) is 1.3-1.7.

2. A mould according to claim 1, in which the cooling system includes at least four arc-shaped tubular sprinklers located along the outer (15), inner (17) and side surfaces (16) of the casting wheel (6) and made with the possibility of adjustable coolant supply: the external sprinkler (11) is located on the side of the outer surface (15) of the casting wheel (6) and the continuous belt (4) and is used to supply coolant to them; the internal sprinkler (12) is located on the side of the inner surface (17) of the casting wheel (6) and is used to supply coolant to it; the right-side sprinkler (10) and the left-side sprinkler (13) are located on the side of the right and left-side surfaces (16) of the casting wheel, respectively, to supply coolant to them.

3. The mould according to claim 2, in which the tubular sprinklers (10, 11, 12, 13) are divided into independent zones by means of internal transverse partitions, in each of which they provide individual control of the coolant flow for regulated supply of coolant independently to each zone.

4. The mould according to claim 2, in which the controlled supply of coolant is carried out through nozzles (7) distributed along the entire length of each sprinkler (10, 11, 12, 13).

5. The mould according to claim 4, in which the coolant flow is regulated by controlling the shut-off valves and the corresponding flow control nozzle units (7).

6. The mould according to claim 4, in which coolant is supplied through flat-flame nozzles with individual coolant flow control units.

7. The mould according to claim 1, in which water is used as a coolant.

8. The mould according to claim 1, which is used for the solidification of aluminium alloys containing at least one alloying element selected from a group including iron, silicon, magnesium, zirconium, scandium, manganese, titanium, copper, nickel and chromium, and the structure of the cast ingot is an aluminium matrix with particles of eutectic origin distributed in it.

9. A method for cooling a continuous cast ingot in the mould according to claim 1, including an adjustable supply of coolant to the casting wheel (6) of the mould (5) and the continuous belt (4) located at least on the sides of the outer surface (15), the inner surface (17) and both side surfaces (16) of the wheel (6) when regulating its flow according to the following ratios: the ratio of the flow rate on the side of the inner surface (17) of the casting wheel (6) to the flow rate on the side of the outer surface (15) of the wheel (6) is in the range of 1.9-3.0; the ratio of the total coolant flow on the side of the side surfaces (16) of the casting wheel to the coolant flow on the side of the inner surface (17) of the casting wheel (6) is in the range of 1.3-1.7.

10. The method according to claim 9, in which coolant is supplied through at least four arc-shaped tubular sprinklers (10, 11, 12, 13), located along the outer (15), inner (17) and side (16) surfaces of the casting wheel (6) and made with the possibility of adjustable coolant supply: an external sprinkler (11) located on the side of the outer surface (15) of the casting wheel (6) and the continuous belt (4) and used to supply coolant to them; an internal sprinkler (12) located on the side of the inner surface (17) of the casting wheel and used to supply coolant to it; and the right-side sprinkler (10) and the left-side sprinkler (13), located on the side of the right and left-side surfaces (16) of the casting wheel (6), respectively, and used to supply coolant to them.

11. The method according to claim 10, in which the tubular sprinklers (10, 11, 12, 13) are divided into independent zones by means of internal transverse partitions, in each of which they provide individual control of the coolant flow for unregulated supply of coolant independently to each zone.

12. The method according to claim 10, in which coolant is supplied through nozzles (7) distributed along the entire length of each sprinkler (10, 11, 12, 13).

13. The method according to claim 12, in which the control of the coolant flow is carried out by controlling the shut-off valves and the corresponding flow control units of the nozzles (7).

14. The method according to claim 12, in which coolant is supplied through flat-flame nozzles with individual coolant flow control units.

15. The method according to claim 9, wherein water is used as the coolant.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0048] The essence of the invention is explained by graphic materials.

[0049] FIG. 1 shows a general view of the mould as part of the casting line, where: 1—continuous cast ingot; 2—metal supply system to the mould wheel; 3—tension wheel of the continuous belt; 4—continuous belt; 5—mould; 6—casting wheel; 7—cooling system nozzles, 8—coolant filter; 9—pressure roller of the continuous belt.

[0050] FIG. 2, including view A, shows the coolant distribution pattern (cooling system) of a mould, where: 4—continuous belt; 6—casting wheel; 10—right-side sprinkler; 11—external sprinkler; 12—internal sprinkler; 13—left-side sprinkler; 14—sprinkler nozzles; 15—outer surface of the wheel; 16—side surfaces of the wheel; 17—inner surface of the wheel, view A shows the second side surface 16.

[0051] FIG. 3 shows a mould in a cross-section, where: 4—continuous belt, 6—casting wheel, 10—right-side sprinkler; 11—external sprinkler; 12—internal sprinkler; 13—left-side sprinkler; 18—casting wheel attachment rings; 19—large base of trapezoidal cross-section, 20—small base of trapezoidal cross-section.

IMPLEMENTATION OF INVENTION

[0052] The following are examples of specific embodiments of the invention.

EXAMPLE 1

Justification of the Choice of Geometric Dimensions of the Cross-Section of the Open Channel of the Casting Wheel Forming a Continuous Cast Ingot in the Form of an Isosceles Trapezoid Using the Procast Software Package

[0053] The purpose of the example is to choose the ratio of the lengths of the bases of the trapezoidal (i.e., in the form of a trapezoid) cross-section of the open channel of the casting wheel ensuring uniform solidification of the metal in a continuous cast ingot.

[0054] The following parameters were used as solidification uniformity criteria with a high production capacity of the casting of at least 2 t/hour: [0055] the presence/absence of vectors of internal tension stresses, primarily in the corners of the large base of the trapezoid; [0056] the depth of the sump of the solidifying melt, the value of which controls the presence/absence of central shrinkage porosity. [0057] the absence of significant thermal gradients within the solidification interval.

[0058] In the presence of multidirectional vectors of tension stresses, the probability of destruction of the ingot (or of occurrence of cracks) during solidification is high.

[0059] In case of a deep sump, the formation of centreline shrinkage porosity is likely due to a change in the thermal gradient during the actual cooling process. The calculations are valid for the cross-section in the range of 1000-3600 mm.sup.2.

[0060] If there is at least one parameter with the maximum result, there is a high risk of getting an unusable ingot. Qualitative modelling results are shown in Table 1.

TABLE-US-00001 TABLE 1 Results of modelling the selection of the trapezoid cross-section The ratio of the Criteria length of the large Multidirection Value of base of trapezoid to of the vector of tension the length of the tension stresses stresses in the small base of in the corners corners of the Item trapezoidal Sump of the large base large base of No cross-section depth of the trapezoid the trapezoid 1 1.1 maximum minimums maximum 2 1.3-1.6 medium medium medium 3 >2.0 minimums maximum medium

[0061] As can be seen from Table 1, with the ratio of the length of the large base to the length of the small base of the trapezoid equal to 1.1, there is a high probability of formation of a deep central sump during solidification, which can lead to the appearance of maximum shrinkage porosity. When the ratio of the length of the large base of the trapezoid to the length of the small base of the trapezoid is about 1, extraction of the ingot from the mould becomes difficult.

[0062] With the ratio of the length of the large base of the trapezoid to the length of the small base of the trapezoid is in the range of 1.3-1.6, the formation of a deep sump is excluded and there are no critical tension stresses.

[0063] If the ratio of the length of the large base of the trapezoid to the length of the small base of the trapezoid is higher than 2, the formation of a deep sump is excluded, however, there is a multidirectional vector of tension stresses in the corners of the large base of the trapezoid, which will contribute to the destruction of the ingot during deformation. At the same time, it should be noted that there is a thermal gradient in the corners of the large base of the trapezoid, which will contribute to the formation of segregation zones and, as a result, to the heterogeneity of the chemical composition of the ingot.

[0064] Based on the results obtained, a mould 5 was made (FIG. 1) with an open channel having a trapezoidal cross-section with a large base 19 and a small base 20, as shown in FIG. 3. The mould 5 contains a casting wheel 6, a continuous belt 4 and a cooling system. The continuous tape 4 is wound through a tightening wheel 3. The belt pressure roller 9 presses the belt 4 to the wheel 6. The casting wheel 6 is installed using attachment rings 18.

[0065] The manufactured mould was installed as part of a cast and rolling mill for the production of wire rods made of aluminium and its alloys with a capacity of 2-5 t/hour. The continuous cast ingot was rolled in the stands of a rolling mill to obtain an aluminium wire rod with a diameter of 9.5; 12; 22 mm at the output.

[0066] During the operation of the mould 5, liquid metal is fed through the metal supply system 2 into the open channel of the casting wheel 6 of the mould 5, then as a result of metal solidification, a continuous cast ingot 1 is formed between the walls of the channel and the continuous belt 4, which is cooled during the entire solidification process by means of a coolant supplied to the outer surface 15, inner surface 17, side surfaces 16 of the casting wheel 6 and the continuous belt 4 through the nozzles 7 of the cooling system.

[0067] The cooling system of the mould 5 includes four arc-shaped tubular sprinklers located along the outer 5, inner 17 and both side surfaces 16 of the casting wheel 6 and made with the possibility of adjustable coolant supply (FIG. 2 with view A):

[0068] an external sprinkler 11 located on the side of the outer surface 15 of the casting wheel 6 and the continuous belt 4 and used for supplying coolant to them;

[0069] an internal sprinkler 12 located on the side of the inner surface 17 of the casting wheel 6 and used for supplying coolant to it;

[0070] a right-side sprinkler 10 and a left-side sprinkler 13 located on the side of the right-side surface and the left-side surface 16 of the casting wheel 6, respectively, and used for supplying coolant to them.

[0071] Nozzles 7 are located: on the internal sprinkler 12 (FIG. 2), divided by internal partitions into three independent zones; on the external sprinkler 11, also consisting of three independent internal zones, as well as on two side sprinklers 10, 13, each of which consists of two independent zones. Each of the above independent zones is provided with an individual water supply control used to control the supply of water to this zone. The cooling control system is configured individually for each independent zone.

[0072] The choice of the type of nozzles is determined by the chosen design of the sprinklers and the wheel (wheel size, distance between the sprinklers and the wheel, etc.), since the nozzles form a jet of coolant of a certain shape. In each specific case, the necessary shape of the jet is determined, according to which the type of nozzle is selected. In this case, flat-flame nozzles were installed.

[0073] For a more accurate individual adjustment of the water flow, a control unit with a needle valve is installed upstream of each nozzle.

[0074] For quick installation/removal of the belt, the right sprinkler and the inner sprinkler can be moved to the side by 20° using a rotary stand (not shown in the drawings).

[0075] The parameters of the cooling system of the mould 5 with water used as the coolant are shown in Table 2.

TABLE-US-00002 TABLE 2 Cooling system parameters 1 Nr. of nozzles 158 pcs. 2 Maximum water flow of the water-cooling system 9.9 l/min

[0076] A self-cleaning filter 8 (for example, a water filter) can be provided in the coolant (for example, water) supply system (FIG. 1).

[0077] Water flow control is carried out in manual and automatic modes. The temperature of the cooling water is controlled before and after the mould 5.

EXAMPLE 2

Determination of the Conditions Ensuring the Obtainment of a Defect-Free Ingot

[0078] A series of studies was carried out showing the influence of various settings of the cooling system, and those parameters of coolant flow control of the system were found that ensure the production of defect-free continuous cast ingots during solidification.

[0079] The melting was performed using an alloy of 6101 type (No 1) and technical aluminium (No 2) as examples, the chemical composition of which is given in Table 3.

TABLE-US-00003 TABLE 3 Chemical composition of alloys, wt. % Item Total content of all No Si Mg Fe Other (each) other impurities 1 0.6 0.5 0.2 <0.05 0.1 2 0.06 <0.001 0.14 <0.05 0.1

[0080] The following parameters were used as quality evaluation criteria of the ingot: [0081] absence of shrinkage holes with a line production capacity of no less than 2 t/hour.

[0082] Coolant (water) control parameters are given in Table 4.

TABLE-US-00004 TABLE 4 Parameters for regulating the ratio of the flow (quantity) of coolant supplied on the sides of the small and large bases of the trapezoid The ratio of the amount of coolant supplied on the sides of the small and large bases of the trapezoid Note 1 <1.9 Production capacity is more than 1.5 t/hour 2 1.9-2.4 Production capacity is more about 2 t/hour 3 2.4-3.0 Production capacity is more than 4 t/hour 4 <3.0 Production capacity is more than 2 t/hour, presence of shrinkage holes in the central part of the ingot

[0083] From the analysis of the results given in Table 4, it follows that when the ratio of the amount of coolant supplied from the small and large base of trapezoidal cross-section of the open channel of the casting wheel is less than 1.9, it is not possible to achieve a production capacity of more than 1.5 t/hour of defect-free cast ingots.

[0084] With the ratio of the amount of coolant supplied from the small and large base of trapezoidal cross-section of the open channel of the casting wheel (the coolant flow from the internal sprinkler to the coolant flow from the external sprinkler) in the range of 1.9-3.0, it is possible to completely eliminate the formation of defects in the form of shrinkage holes and to ensure a line production capacity of more than 2 tons/hour of ingots (more than in the prototype), which was confirmed by metallographic studies of the internal structure of the templates of continuous cast ingots.

[0085] The most preferable is the ratio of the flow rate (amount) of coolant supplied on the sides of the small and large bases of trapezoidal cross-section of the open channel of the casting wheel (the coolant flow from the internal sprinkler to the coolant flow from the external sprinkler) in the range of 1.9-2.4, which ensures the maximum production capacity of the casting line.

[0086] The analysis of the templates showed that when using a mould containing a casting wheel with an open channel of the proposed trapezoidal cross-section, with the specified adjustment settings of the mould cooling system, namely, the ratio of water flow on each sprinkler, it is possible to exclude defects of crystallisation origin in the form of shrinkage holes, cracks of crystallisation origin, while the number of segregates in the corners of large base of the trapezoid (wheel channel cross-section) turned out to be minimal, this was confirmed by the results of a metallographic study of the internal structure of the templates of a continuous cast ingot and is acceptable from the point of view of the ingot quality.

[0087] Analysis of the microstructure of a cast ingot made of alloy 6101 (composition No 1 in Table 3) showed that the typical structure of the ingot is represented by an aluminium solution of silicon and magnesium in aluminium and veins of eutectic iron-containing phases. Analysis of the structure of a cast ingot made of technical aluminium (composition No 2 in Table 3) showed that the structure is represented by an aluminium solution with veins of eutectic iron-containing phases. At the same time, the calculated cooling rate within the solidification interval of 6101 alloy and technical aluminium (Table 3) in the entire cross-section was at least 10 K/s. Due to the high cooling rate implemented when using the proposed mould, the structure of the known industrial alloys containing iron, silicon, magnesium, zirconium, scandium, manganese, titanium, copper, nickel and chromium will be represented mainly by an aluminium solution and eutectic phases formed by the corresponding alloying elements.

[0088] The use of the claimed mould allows to obtain a continuously cast ingot of high quality (practically without defects), which can be further processed into a product with lower production costs, i.e., the claimed mould allows to increase the manufacturability of the ingot. At the same time, a high production capacity of more than 2 t/hour of the casting line is ensured.