RU2628805C2 - Rotary casting machine to produce copper workpiece in casting and rolling plant - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: rotary casting machine contains a frame on which a casting wheel and a tension wheel are mounted, which are covered by endless movable belt that, together with the calibre in the casting wheel, forms a movable crystalliser. The radial section of the crystalliser has trapezoidal shape with upper wide base 15 and a lower narrow base in the form of oblique triangle 17, which three lower corners β₁, β₂, β₃ equal to each other. In the casting wheel grooves an additional cavity 21 with a radius r is made which results in increase of cooling intensity in given area relative to the workpiece.

EFFECT: elimination of defects along cracks in the middle of the lower base of the workpiece trapezoidal cross-section, elimination of workpiece breaks along said cracks during casting and subsequent rolling of the workpiece.

2 cl, 3 dwg

Description

The invention relates to the field of metallurgy and can be used in the manufacture of copper wire rod in the combined process of casting and rolling.

A known method of casting a workpiece in a five-roller rotary casting machine, comprising forming a casting trough between the center wheel of the machine and the female tape and pouring liquid metal into the entrance of this trough; the entrance to the casting trough is horizontal (see the article “Strip casting and rolling units for the production of strips of non-ferrous metals.” AV Chebotarev, A.Yu. Shevchenko, AV Samsonov. Heavy engineering. 5/1997 Page 10. Position 1 in the figure).

The disadvantage of a five-roller machine is its large mass and cost.

A known method of casting aluminum billets in a two-roll casting machine, including the formation of a casting trough between the lower wheel and the enclosing tape (see article "Foundry-rolling units for the production of aluminum and copper wire rod". A.Yu. Shevchenko, VA Chebotarev and others Heavy Engineering 5/1997, p. 12. Position 1 in the figure).

The advantage of this method is less likely to get gas bubbles into the liquid metal during the casting process.

A disadvantage of the known technical solution is the likelihood of transverse temperature cracks in the middle of the lower base of the cross section of the cast billet.

The technical result from the use of the invention is the elimination of marriage through transverse cracks in the middle of the lower base of the trapezoidal cross section of the workpiece, as well as the elimination of breakage of the workpiece along these cracks during casting and subsequent rolling of the workpiece due to local reduction in the temperature of the workpiece in places where these cracks are localized due to an increase in the process cooling the workpiece in the specified area.

This technical result is achieved by using a rotary casting machine to obtain a copper billet in a casting and rolling unit, including a frame in which two wheels are installed: an upper tension and a lower calibrated foundry covered by an endless movable tape, which together with a caliber cut into the foundry the wheel, form a movable mold having a trapezoidal shape in radial section with upper wide and lower narrow bases, and at the entrance to the mold, the movable tape is pressed against the caliber, made in a casting wheel, using a pressure roller, the narrow base of the trapezoid is convex in the form of an isosceles triangle; the horizontal axis of the pinch roller is aligned with the horizontal axis of the casting wheel, and the trapezoid with a convex narrow lower base, which is a radial section of the caliber in the casting wheel, is characterized in that a groove is made in the creek of the calibrated casting wheel around the apex of an isosceles triangle, outlined with a radius r.

To illustrate the proposed technical solution, drawings are used.

FIG. 1. Scheme of a rotary machine, side view.

FIG. 2. The radial section (AA in Fig. 1) of the stream in the casting wheel of a rotary casting machine along with the cast billet.

FIG. 3. The lower base of the trapezoidal cross section of the cast billet.

The foundry machine includes: a frame 1 (Fig. 1), on which a casting wheel 2 and a tension wheel 3 are mounted, covered by an endless movable belt 4, which in combination with the casting wheel 2 forms a movable mold.

A mixer 5 is installed near the frame 1 (more precisely, in Fig. 1, the position 5 denotes the point relative to which the mixer is tipped over) with the bathtub 6 and the feeder tube 7. On the input side of the movable mold, the endless belt 4 is pressed against the casting wheel 2 with a pressure roller 8 driven by a pneumatic cylinder 9. A cast billet 10 (Fig. 2) emerging from the movable mold is shown by a dot-dash line 11 in the form of a trajectory of its movement.

The pressure roller 8 is designed to ensure the correct cross-sectional shape of the cast billet 10. For this purpose, its horizontal axis is aligned with the horizontal axis of the casting wheel 2.

Works installation for casting the workpiece as follows.

The liquid metal is poured into the mixer 5, from which it is fed into the bath 6 and then dispensed by the feeder tube 7 to the inlet of the movable mold. On the working length L of the mold when the casting wheel 2 is rotated clockwise (see arrow 12), the liquid metal solidifies, and at the exit 13 from the mold, a workpiece with a cross section (Fig. 2) is obtained in the form of a trapezoid with a convex narrow lower base, which is the radial section of the caliber in the casting wheel 2, and characterized in that all three lower corners in it are equal to each other. Continuously moving out of the mold, the workpiece moves along a curved path 11 and at the exit from the casting machine has the form of a workpiece 14, straightened in a straight line.

A radial section of the gauge in the casting wheel 2, having the form of a trapezoid with a convex narrow lower base and shown in FIG. 2, is characterized by the equality of angles β ₁ = β ₂ = β ₃ = β.

To build a mathematical expression that calculates the angle β, we use the following system of equations:

Δβ = (β ₁ -90 °) -α

Δβ = (180 ° -β ₂ ) / 2

Δβ ₁ = β ₂ ,

where Δβ is an intermediate parameter.

Solving this system of equations, we obtain the working formula:

β = 120 ° + 0.67α

If we take the angles of release, for example, α ₁ = α ₂ = α = 9 °, then the angles β can be calculated as follows:

β = 120 ° + 0.67⋅9 ° = 126 °

The cross section of the cast billet shown in FIG. 2 includes: an upper base 15, two lateral faces 16 and a convex lower base in the form of an isosceles triangle 17, the vertex 18 of which divides the lower base into two separate cooling zones 19 and 20.

,Around point 18, relative to the center of the semicircle, a protrusion 21 is outlined (Fig. 3), and the radius of the semicircle can be calculated by the empirical formula

,

where F ₀ is the cross-sectional area of the cast billet, mm ² .

We define the ratio α _{0 of the} cooled surface of the workpiece to the cooled volume (more precisely, the cooled perimeter to the cooled area).

We will do this with numerical examples: in the first of them, the cross-sectional area of the workpiece is F ₀ = 1000 mm ² , and in the second, F ₀ = 2500 mm ² .

In the first example, the cooled perimeter

C ₀ = 4a ₀ = 4⋅31.5 = 125 mm

where a ₀ = 31.5 mm is the side of the conditional square, which is found as

Perimeter to Square Ratio

α ₀ = C ₀ / F ₀ = 125/1000 = 0.125

The degree of cooling intensity of the workpiece as a whole

β ₀ = α ₀ = 0.125

The radius of the protrusion on the lower base of the cross section of the workpiece

The cooling perimeter on the protrusion of the lower base

C ₁ = (πr) = 3.14⋅4.0 = 12.5 mm

The cooled cross-sectional area of the protrusion 21 (Fig. 3)

F ₁ = (πr ^2/2) = 3,14⋅4,0 ^2/2 = 25.0 mm ²

The ratio of the cooled perimeter to the cooled area

α ₁ = C ₁ / (F ₁ ) = 12.5 / 25.0 = 0.500

The degree of intensity of cooling of the protrusion 21

β ₁ = α ₁ / K ₁ = 0.500 / 2 = 0.250

where K ₁ -2 is the coefficient of recharge of heat from the outside.

The ratio of the intensity of local cooling of the protrusion 21 to the average intensity of cooling of the workpiece as a whole

η = β ₁ / β ₀ = 0.250 / 0.125 = 2.0

In the second example (F ₀ = 2500 mm ² )

C ₁ = 3.14⋅5.0 = 15.7 mm

β ₁ = 0.400 / 2 = 0.200

C ₀ = 4⋅50 = 200 mm

α ₀ = 200/2500 = 0,080

β ₀ = α ₀ = 0.080

F ₁ = 3,14⋅5 ^2/2 = 39.3 mm ²

α ₁ = 15.7 / 39.3β ₀ = α ₀ = 0.080

F ₁ = 3,14⋅5 ^2/2 = 39.3 mm ²

α ₁ = 15.7 / 39.3 = 0.400

β ₁ = 0.400 / 2 = 0.200

η = 0.200 / 0,080 = 2,5

раза, а температура выступа 21 получается на 40…60°C ниже, чем в целом по заготовке 10.So, the intensity of local cooling on the protrusion 21 (Fig. 3) is 2.0 ... 2.5 times higher than in the workpiece as a whole. This is due to the fact that at the bottom of the caliber there is a depression with a radius r; as a result, the cooled perimeter increases in

times, and the temperature of the protrusion 21 is obtained at 40 ... 60 ° C lower than in the workpiece 10 as a whole.

This provides the following benefits:

a) eliminates the risk of transverse cracks in the middle of the lower base of the cross section of the workpiece, which arise in the process of its extension after leaving the mold;

b) as a result, gaps in the workpiece that arise during its casting, as well as during its subsequent rolling, are eliminated; and this eliminates emergency situations in the casting and rolling unit;

c) hidden cracks in the billet are eliminated, and subsequently in finished hire; and this excludes the receipt of defective products.

Claims (4)

1. A rotary casting machine for producing a copper billet in a casting and rolling unit, comprising a frame in which an upper tensioning wheel and a lower calibrated casting wheel are mounted, enclosed by an endless movable tape, which together with a caliber cut in the casting wheel forms a movable mold having in a radial section the shape of a trapezoid with upper wide and lower narrow bases, and the narrow base of the trapezoid is made with a hollow in the form of an isosceles triangle, characterized in that in the creek ibrovannogo casting wheel around the vertex of the isosceles triangle formed additional cavity having a cross-sectional view of a semicircle. 2. The rotary foundry machine according to claim 1, characterized in that the radius r of the additional cavity is determined by the dependence

, where F ₀ is the cross-sectional area of the caliber, mm ² .

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