JPH10193080A - Crucible-shaped automatic pouring furnace - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To adopt a crucible-type induction furnace that keeps a high-temperature molten metal or keeps it at a high temperature, and makes it possible to perform constant-rate tapping by tilting tapping. A crucible (1) has a hot water chamber (T) having a substantially rectangular cross-sectional shape, and at least tilted from the rated hot water quantity and rated from the vicinity of the surface of the crucible rear wall (12) when the hot water flows first. The rear wall 12 of the crucible between the vicinity of the surface of the crucible rear wall 12 in the tilted state when the amount of hot water is discharged is formed in an arc shape, and the side sectional shape of the hot water chamber T is formed in a substantially sector shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic pouring furnace for dispensing a fixed amount of molten metal into a mold using a crucible-shaped induction furnace.

[0002]

2. Description of the Related Art As an automatic pouring furnace for dispensing a fixed amount of molten metal into a mold while keeping a high temperature (around 1500 ° C.) of molten metal, a closed hot water chamber provided with a U-shaped grooved inductor opening on a wall surface near the bottom, It is an open duct that extends substantially horizontally from the end of a communication passage that opens into the hot water chamber and rises obliquely upward through the refractory that forms the hot water chamber, the upper surface of which is open, and the tap hole is opened at the lower part of the front end. A tap hole, a tap port that opens into the hot water chamber on the opposite side of the tap hole and communicates through a refractory with a hot water receiving section provided at a position higher than the tap hole, and is compressed at an upper portion of the closed hot water chamber. It consists of a pipe for supplying and discharging gas, and always keeps the closed hot water chamber at atmospheric pressure to keep the level of the closed hot water chamber, the tap hole, and the receiving port same, and at the time of tapping, first, a gas called pre-level pressure is used. Pressure is supplied to the closed hot water chamber through the gas pipe to press the surface of the closed hot water chamber. Lower, raise the level of the hot and cold outlets to the level of the inlet of the open duct of the hot tap, and then add the gas pressure corresponding to the hot water amount called the shot pressure to the pre-level pressure for a predetermined time to add the molten metal. A pressurized grooved type automatic pouring furnace that feeds the molten metal into the mold through an opening hole and discharges the gas pressure when the pouring is completed to return the pressure of the closed chamber to the atmospheric pressure and complete the pouring cycle is known. Have been.

Further, as another automatic pouring furnace, a crucible-type induction furnace having a closed furnace lid for sealing the upper portion of the crucible is used in the closed hot water chamber, and two tubes formed of a refractory called Stoke are used. One end of each is immersed in the molten metal in the bath room, and the other end is passed through the closed furnace lid while being kept airtight and connected to the outlet and the receiving port respectively. 2. Description of the Related Art A pressurized crucible-type automatic pouring furnace configured by connecting pipes for supplying and discharging is known. The pouring operation of the pressurized crucible type automatic pouring furnace is substantially the same as the pouring operation of the pressurized groove type automatic pouring furnace.

[0004]

However, in the construction of the conventional automatic pouring furnace, pressure control is required in any case, and in the former case using a grooved inductor, the temperature in the groove is changed to the temperature of the hot water chamber. Since the temperature of the molten metal in the hot water chamber is kept high or raised by heat conduction (50-150 ° C), the refractory of the grooved inductor will be even higher in furnaces pouring at a high temperature of around 1600 ° C. The exposure shortens the service life, and there is a problem that the inspection and maintenance take time and cost. In the case of using the latter stalk, the part left immersed in the molten metal has a short life, so the inspection and maintenance There is a problem that it takes time and effort.

A tilting-type crucible-type induction furnace is known as a pouring furnace which does not have these problems. However, in the conventional construction, the melting chamber of the crucible has the same cylindrical shape as that of the melting furnace and has a unit tilt angle per unit. Since the amount of hot water is not constant, it is difficult to control the tilt of the hot water in a constant amount, and thus it is difficult to perform automatic pouring. The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to employ a crucible-type induction furnace that keeps a high-temperature molten metal or keeps it at a high temperature, and determines the amount by tilting tapping. An object of the present invention is to provide a crucible-shaped automatic pouring furnace in which tapping can be easily performed.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a crucible made of a refractory, a tap hole for discharging molten metal in the crucible, and a crucible wound outside the crucible. In a crucible-type automatic pouring furnace comprising a heating coil for electromagnetically heating the molten metal in the crucible and a tilting device for tilting the crucible so as to tilt the crucible to discharge a fixed amount of water from a tap hole, The crucible in the tilted state when the rated hot water is discharged from the vicinity of the surface of the crucible rear wall at the time of tilting from the rated hot water and flowing out of the hot water for the first time while forming the cross section of the chamber into a substantially rectangular shape. By forming the rear wall of the crucible between the vicinity of the molten metal surface position of the wall in an arc shape and forming the side sectional shape of the hot water chamber into a substantially sector shape, the tapping amount per unit tilt angle is made substantially constant, Fixed quantity tapping control To allow in.

[0007] In the above structure, the arc-shaped portion of the rear wall of the crucible can be formed by an arc whose center is substantially one point from the tip of the tap hole to the contact point between the crucible and the tap hole. In addition, by providing an induction heating funnel between the automatic pouring furnace and a mold for casting the hot water discharged from the automatic pouring furnace, the crucible is tilted rapidly so that the amount of hot water for one time can be reduced in a short time. Reduces the drop in hot water temperature due to the long tapping time and allows the casting time to stay in the funnel in accordance with the speed at which the hot water is poured into the mold. Can be made substantially constant.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1A and 1B show the construction of a main part of an embodiment of the present invention. FIG. 1A is a sectional side view of a furnace body, and FIG. The figure which showed the gate by the virtual line is shown. In FIG. 1, reference numeral 1 denotes a crucible made of a refractory which holds a molten metal and tilts around a tilting fulcrum O by a tilting device (not shown), which will be described later. A tap hole 1b for tapping a molten metal corresponding to O, a tap port 1a and a crucible 1
2 is a heating coil wound in a rectangular shape along the outer periphery of the crucible 1 for inductively heating the molten metal, and 3 converges the magnetic flux of the heating coil 2 to reduce the leakage of the magnetic flux to the structure. 4 is a furnace shell for supporting the crucible 1, the heating coil 2 and the yoke 3, 5 is a furnace lid for suppressing heat loss from the crucible 1, and 6 is a molten metal.

The crucible 1 is arranged with respect to the axis of the tilting fulcrum O.
Front wall 11, rear wall 12, and bottom wall 13 having parallel inner wall surfaces
And a left side wall 14 and a right side wall 15 having a right inner wall surface, the cross section of the hot water chamber T is a quadrangular crucible, and the rear wall 12 of the crucible 1 is tilted from the rated hot water amount and initially The portion located between the vicinity of the surface of the molten metal 6 when the molten metal 6 flows out and the vicinity of the surface of the molten metal in the tilted state when the rated amount of molten metal is discharged is defined by the tip of the tap hole 1a, that is, the tilting fulcrum O as the center of the arc. It is formed of an arc-shaped portion 12a, which is formed by the arc-shaped portion 12a and a linear portion connected to the upper end. The lower end of the arc-shaped portion 12a is continuous with the bottom wall 13. Due to this wall shape, the hot water chamber T has a substantially fan-shaped side cross section.

On the outside of the crucible 1, there are a heating coil 2 and a yoke 3 which is divided into a plurality of parts on the outer periphery of the heating coil 2 and supports the heating coil 2 from outside. 4 are arranged at the outermost periphery. Although not shown, the furnace body thus configured is attached to a furnace frame having a tilt axis whose axis coincides with the tilt fulcrum O, and the furnace frame includes a bearing that receives the tilt axis. The furnace seat is provided with a hydraulic cylinder that pushes up the furnace frame from left and right. That is, the furnace frame, the furnace seat, the hydraulic cylinder and the like constitute a tilting device for the crucible 1.

In this embodiment, since the tilting fulcrum O coincides with the tip of the tap hole 1a, a fixed-point tapping into a mold (not shown) becomes possible, and pouring of the mold into the tap hole is facilitated. Similarly, as shown in FIG. 1B, the inner surfaces of the front, rear, left, and right walls of the crucible 1 are flat except for the corners, but the inner surfaces of the respective walls are slightly curved outward ( When the crucible is inflated, it is easy to form the crucible with the refractory.

Similarly, the cross section of the outer periphery of the crucible 1 is a quadrangle similar to the hot water chamber T, but may be circular. In this case, the heating coil 2 is also circular along the outer periphery of the crucible 1. Can be wound. FIG. 2 is a configuration diagram of a main part of another embodiment of the present invention. In FIG. 2, reference numeral 7 denotes a funnel made of a refractory formed by cutting the inside into a conical shape with a pointed tip facing downward, and forming a tap hole at a lower portion, 8 denotes a heating coil wound around the outer periphery of the funnel 7, and 9 denotes a molten metal. 1 shows a mold that is cast and cooled to form a casting. Other configurations are the same as those in FIG.

In the structure shown in FIG. 2, the molten metal discharged by the tilting of the crucible 1 can be poured while being received by the funnel 7 and keeping the temperature at the same time as the cup speed of the mold 9. That is, the crucible 1 is quickly tilted so that the amount of hot water for one time is discharged from the funnel 7 in a short time, thereby suppressing a drop in the hot water temperature due to a long tapping time. The funnel 7
The molten metal is poured into the mold in accordance with the speed at which the mold is swallowed. The temperature of the molten metal remaining in the funnel 7 during the pouring into the mold is compensated by the heating coil 8 on the outer periphery thereof. It has become. Therefore, the molten metal can be poured smoothly into the mold in accordance with the swallowing speed and at a substantially constant casting temperature.

FIG. 3 shows a change in the level of the molten metal when the crucible of FIG. 1 (or FIG. 2) is tilted. In FIG. 3, a portion surrounded by symbols O, 1b, A, B, and C is a tap hole 1a.
2 shows a side section of a hot water chamber T (see FIG. 1) of the crucible 1 including the crucible 1 (see FIG. 1). O indicates a tilting fulcrum, 1b indicates a contact point between the crucible and the tap hole 1a (see FIG. 1). Also, the radius R ₁
The arc of the trajectory of the contact point 1b when the crucible 1 is tilted, the radius R ₂ is also shown the trajectory of the arc-shaped portion 12a of the wall 12 of the crucible, it tilts the crucible as a fulcrum fulcrum of inclination O,
When the rated molten metal surface rises while keeping the horizontal level and the molten metal surface exceeds the contact point 1b, the molten metal is discharged along the tap hole 1a.

The tap hole 1a is connected to the crucible 1 from its tip.
A downward slope of γ ° with respect to the horizontal
And the rated molten surface rises while maintaining the level
Tilting of the molten metal 6 above the contact point 1b when the molten metal 6 begins to flow
Generally, the angle is set to γ ° or more. The hot water
The tilt angle at which the surface of the molten metal 6 begins to flow over the contact 1b
γ ° + σ °, and the molten metal surface goes out beyond the contact 1b once.
The angle at which the molten metal can be poured, for example, α ° + γ ° +
When it is tilted to σ °, the contact point 1b between the crucible and the tap hole becomes the point P
₁Go to Then point P from O₁Point from the extension line passing through
P₁The line obtained by subtracting σ ° from the starting point is the radius R_TwoArc of
The point of intersection with P_TwoAnd P₁The line drawn horizontally from is the radius
R_TwoThe point that intersects the arc of P_ThreeSurrounded by hatching
Area S ₁(Point P₁, P_Two, P_ThreeThe face of the sector surrounded by
Product) was taken out by tilting α ° + γ ° + σ °
It is proportional to the amount of molten metal. That is, the tilt angle α ° + γ ° + σ
Is the angle at which the molten metal does not flow, and α
(Corresponding to the line P sandwiching the angle α °)₁P_Three= X
₁And line P₁P_Two= Z (see FIG. 4)
Area of part S₁) Is proportional to the amount of hot water.

Similarly, when the tilt angle is α ° + γ ° + σ °
+ Δα °, the area S ₂ (see FIG. 4B) of the sector surrounded by the points P ₁₁ , P ₂₁ , and P ₃₁ is obtained, and S ₂ −S ₁ =
When ΔS is obtained, the ΔS is ΔΔ at α ° + γ ° + σ °.
It is proportional to the amount of molten metal discharged when additional tilting α °. In addition,
When calculating the areas S ₁ and S ₂ of the sector, even if this area is substituted for the area of the triangle P ₁ P ₂ P ₃ or P ₁₁ P ₂₁ P ₃₁ , the area of the arc-shaped part is negligible for Δα °. Since there is almost no error, S ₁ and S ₂ are substituted by the area of a triangle.

The area S ₁ of the triangle, as shown in FIG. 4 (a), between OP ₁ between R _1, OP ₂ R _2, an angle related to the pouring amount of the tilting angle alpha °, The tilt angle at which the rated molten metal level exceeds the contact point 1b after the level of the tap hole 1a becomes horizontal is σ.
°, when the linear OP ₃ and the angle of beta ₁ ° which makes with the horizontal line, S ₁ is a distance Y ₁ to perpendicular drawn from P ₂ intersects line P ₁ P ₃ high Satoshi line P ₁ P ₃ comprising a length X ₁ in the area of the triangle having the base.

Here, X ₁ is X ₁ = R ₂ × COS β ₁ ° -R
₁ × COS (α ° + γ °) and the line P ₁
Assuming that the length of P ₂ is Z, Y ₁ is Y ₁ = Z × sin α °
Is required. Further, when Z draws a line OQ which passes through the point O and is parallel to Z, the angle P ₁ OQ is σ °, so that the angle P ₂ O
If Q is ε °,

[0019]

## EQU1 ## Z = R ₂ × cos ε ° −R ₁ × cos σ °. Then, R ₂ × sinε ° = R ₁ × sin σ °
Therefore, sinε ° = R ₁ × sinσ ° /
R ₂ and therefore cos ε ° = [1- (R ₁ × sin σ)
° / R ₂ )] ^1/2 , and Z can be determined from the following equation that applies this to the previous equation.

[0020]

## EQU2 ## Z = R ₂ × [1- (R ₁ × sin σ ° /
R ₂ )] ^1/2 −R ₁ × cos σ ° Note that this Z, that is, the length of the line P ₁ P ₂ starts from the point P ₁ from the line passing through P ₁ from the point O and reaching the arc of radius R _2. Is the distance to the point where the line minus σ ° intersects the arc of radius R ₂ , and is constant regardless of the tilt angle.
That is, it is equal to the length of a line P ₁₁ P ₂₁ described later with reference to FIG.

Therefore, the area S ₁ of the triangle can be obtained by the following equation.

[0022]

[Equation 3] S₁= Y₁× X₁/ 2 = Z × sin α ° × [R_Two× cosβ₁° -R₁× cos (α ° + σ °)] / 2 Similarly, the area S of the triangle_TwoIs shown in FIG. 4 (b).
Sea urn, OP₁₁R between₁, OP_{twenty one}R between_TwoOf the tilt angle
The angle related to the amount of hot water is α ° + Δα °, and the tap 1a
Tilt angle at which the rated surface level exceeds contact 1b after leveling
To σ °, line OP ₃₁Is the angle formed by the_Two° and
Then S_TwoIs P_{twenty one}The perpendicular drawn from the line P₁₁P₃₁Exchange
Distance Y_TwoIs the height and the line P₁₁P₃₁Length X_TwoTo
It is the area of the triangle to be the base.

Where X_TwoIs X_Two= R_Two× COS β_Two° -R
₁× COS (α ° + γ ° + Δα °). Ma
As mentioned earlier, the line P₁₁P_{twenty one}Is the length in FIG.
Line P ₁P_TwoIs the same Z as the length of_TwoIs Y_Two
= Z × sin (α ° + Δα °). did
Therefore, the area S of the triangle_TwoCan be calculated by the following equation
it can.

[0024]

Equation 4] _{S 2 = Y 2 × X 2} /2 = Z × sin (α ° + Δα °) × [R 2 × cosβ 2 ° -R 1 × cos (α ° + γ ° + Δα °)] / 2 Then, R ₂ × sin β ₁ ° is R ₁ × sin (α ° + σ
°) or R ₂ × sin β ₂ ° is R ₁
We obtain a beta ₁ ° or beta ₂ ° using the equals × sin (α ° + σ ° + Δα °), and, R ₁ = 0.54
5 m, R ₂ = 1.251 m, Δα ° = 1 °, and for any α ° between the angle of 20 ° when the rated hot water is first started and the tilt angle 60 ° until the rated hot water is discharged. Table 1 shows S ₂ −S ₁ = ΔS obtained by setting Δα ° = 1 °, and ratios of ΔS at other tilt angles are displayed based on ΔS at a tilt angle of 20 ° as a reference (1.0).

[0025]

[Table 1] As shown in Table 1 above, the error of the tapping amount per unit tilting angle at each tilting angle is ± 2.4% at the maximum, and the tapping amount for the mold falls within the normally required tolerance of ± 3%. This has been confirmed on actual equipment.

On the other hand, as shown in FIGS. 5A and 5B,
The center of the arc of the arc-shaped portion 12a of the crucible rear wall is set in the above embodiment.
To the tip of the spout 1a, and the point of contact between the crucible and the spout
1b, the arc on the rear wall of the crucible is the contact 1b (= P
₁= P₁₁) And radius R _Three= R_Two-R₁Arc
become. Therefore, the area S₁Form the angle α °
Two sides P sandwiching₁P_TwoAnd P₁P_ThreeOr area S_TwoThe shape
Two sides P sandwiching the formed angle α ° + Δα °₁₁P_{twenty one}And P₁₁P
₃₁Is R_ThreeAnd the lengths are equal,
There is no error at any tilt angle of 60 °.
This is clear from the following equation.

[0027]

Equation 5] ^{_{ΔS = π × R 3 2 ×}} (α ° + Δα °) / 360-π × R 3 2 × α ° / 360 = π × R 3 2 × Δα ° / 360 That is, [Delta] S for the [Delta] [alpha] ° alpha ° independent of
The error due to the tilt angle becomes zero over the entire tilt range.

From the above, if the fulcrum of the arc is selected at any one point between the tip of the tap and the contact point between the tap and the crucible,
It can be seen that all can be made within the allowable error range ± 3%. That is, by forming the rear wall 12 of the crucible 1 in an arc shape having a point substantially between the tip of the tap hole 1a and the contact point 1b between the crucible and the tap hole, the tapping amount per unit tilt angle is substantially reduced. It becomes constant, and it becomes very easy to control the amount of hot water by controlling the tilt angle.

Referring to FIG. 3, the center of the arc of the arc-shaped portion 12a of the crucible rear wall is set at the tip of the tap hole 1a of the above embodiment (FIG. 1 or FIG. 2). In the case where the contact 1b is used, the total tapping amount, that is, the effective tapping amount (in the range of α ° = 20 to 60 °) is the difference _SD.
As shown by, the latter is reduced by about 6% (that is, the effective tapping amount is reduced to 94%) of the former, and the remaining tapping height, that is, the crucible height in the tilting state after tapping the effective tapping amounts of both, is , as shown by the difference C _H latter becomes about 10% less of the former. Therefore, in the latter case, it is necessary to increase the crucible width by about 6% or to increase the radius of the circular arc by about 3% in order to secure the same effective hot water amount as the former.

When the temperature is maintained in a tilted state, the area of the molten metal facing the heating coil is reduced by about 10% in the latter. That is, it is not preferable to simply increase the diameter of the arc of the rear wall of the crucible because it causes an increase in error. However, as shown in FIG. 1 or FIG. By forming the arc-shaped portion of the rear wall 12 with an arc having a large diameter, the height from the bottom of the crucible to the rated molten metal surface can be increased, and the molten metal facing the heating coil when keeping the temperature in a tilted state Because the area of can be enlarged,
Heating power can be easily supplied to the same amount of remaining hot water, so that the electric efficiency of the heating coil is improved and the running cost can be reduced. Further, the opening area of the crucible can be reduced, and the installation area can be reduced accordingly.

[0031]

According to the present invention, since the cross section of the hot water chamber of the crucible is formed in a substantially rectangular shape and the side cross section is formed in a substantially sector shape, the amount of hot water per tilt angle becomes substantially constant. By replacing the control of the amount of hot water with the control of the tilt angle, it is possible to discharge water with high accuracy, and it has the effect of making tilt control extremely easy during automatic pouring. It has the effect of being able to handle molten metal.

[Brief description of the drawings]

FIG. 1 shows a configuration of a main part of an embodiment of the present invention, (a) is a side sectional view of a furnace body, and (b) is a PP of (a).
A view of the pouring gate shown by a virtual line in the arrow view

FIG. 2 is a configuration diagram of a main part of another embodiment of the present invention.

FIG. 3 is a diagram showing a change in the molten metal level when the crucible of FIG. 1 is tilted.

FIG. 4 shows a partial view of FIG. 3, wherein (a) shows a tilt angle α °;
+ Γ ° + σ °, the change in the molten metal level, and (b) shows the change in the molten metal level when the tilt angle is α ° + γ ° + σ ° + Δα °.

FIG. 5 is a diagram showing a change in the molten metal surface when the center of the arc of the crucible rear wall is a contact point 1b between the crucible and the tap hole, and (a) shows a molten metal when the tilt angle is α ° + γ ° + σ °. Surface change diagram,
(B) is a change diagram of the molten metal surface when the tilt angle is α ° + γ ° + σ ° + Δα °.

[Explanation of symbols]

 Reference Signs List 1 crucible 1a tap hole 1b contact point between crucible and tap hole 2 heating coil 3 yoke 4 furnace shell 5 furnace lid 6 molten metal 7 funnel 8 heating coil 9 mold 11 front wall 12 rear wall 12a arc-shaped portion 13 bottom wall 14 left side wall 15 Right side wall T Yumuro

Claims (3)

[Claims] 1. A crucible made of a refractory, a tap hole for tapping the molten metal in the crucible, a heating coil wound around the outside of the crucible for electromagnetically heating the molten metal in the crucible,
In a crucible-type automatic pouring furnace having a tilting device for tilting the crucible and tilting the crucible so as to discharge a fixed amount of water from the tap hole, the crucible has a cross section of the hot water chamber formed in a substantially square shape, At least after the crucible between the vicinity of the surface of the crucible rear wall when tilting from the rated hot water and the first hot water flows and the vicinity of the surface of the crucible rear wall in the tilting state when the rated hot water is discharged. A crucible-shaped automatic pouring furnace, wherein a wall is formed in an arc shape and a side sectional shape of a hot water chamber is formed substantially in a sector shape. 2. The crucible-shaped automatic pouring furnace according to claim 1, wherein the arc-shaped portion of the rear wall of the crucible is substantially centered at one point between the tip of the tap hole and the contact point between the crucible and the tap hole. A crucible-shaped automatic pouring furnace characterized by being formed in an arc. 3. The crucible-type automatic pouring furnace according to claim 1, wherein an induction heating funnel is provided between the automatic pouring furnace and a mold for casting hot water discharged from the automatic pouring furnace. A crucible-shaped automatic pouring furnace.