KR101450870B1 - Heating apparatus for billet - Google Patents

Abstract

Achieves the heating ability and the thermal efficiency equal to or higher than the electromagnetic induction heating method. A main body case 2 made of a frame 3 in which a furnace wall is not provided but communicated inside and outside and a billet W A skid rail 5 attached to the body case 2 for supporting the billet W in its entirety and an outer surface extending over the entire circumference of the billet W, And a plurality of pure oxygen or oxygen enrichment burners 4 for heating the billet W by colliding with a combustion flame. The ratio D / L of the diameter D of the nozzle 12 to the distance L from the outer surface of the billet W to the nozzle 12 of the burner 4 is 0.02 to 0.04, The pitch P is set to 30 to 50 times the diameter D of the nozzle 12.

Description

{HEATING APPARATUS FOR BILLET}

The present invention relates to a billet heating apparatus for extrusion molding such as an aluminum alloy or a copper alloy.

A billet for extrusion molding (hereinafter referred to as a billet) made of a round bar such as an aluminum alloy or a copper alloy billet produced by continuous casting is heated by a billet heating apparatus to the entire billet at an extrusion molding temperature And then molded into a predetermined shape by an extrusion molding machine in the process on the downstream side.

Conventionally, as a method for heating a billet, there are an electromagnetic induction heating method and a burner-based combustion heating method. The electromagnetic induction heating method has a drawback that the heating ability is high, but the operation cost is high due to the power consumption. The combustion heating method using a burner has a lower operating cost than the electromagnetic induction heating method. However, since the heating capability is low, it is necessary to lengthen the length of the furnace to secure the heating time, .

Patent Literature 1 and Patent Literature 2 disclose a method of charging a billet into a furnace and heating the burner toward the outer peripheral surface of the billet. This type of heat transfer is the heat transfer from the furnace wall and convection heat from the flame.

Since the billet made of an aluminum alloy or a copper alloy has a low emissivity, the amount of radiant heat from the furnace wall is small, and the flame is heated toward the outer peripheral surface of the billet in order to compensate for this. However, since the flame from the burner is a combustion type by air, the amount of convective heat is small and it can not be heated in a short time like the electromagnetic induction heating system.

(Patent Document 1)

Microfilm of element 57-2613, Japan (Room 57-147256)

(Patent Document 2)

Japanese Patent No. 3085620

SUMMARY OF THE INVENTION It is an object of the present invention to provide a billet heating apparatus capable of achieving a heating capability and a thermal efficiency equal to or higher than an electromagnetic induction heating system.

In order to solve the above problems, a billet heating apparatus according to the present invention comprises:

A main body case made of a frame in which a furnace wall is not installed but which is communicated with the inside and outside,

A skid rail for supporting the billet loaded in the main body case to an atmospheric release state,

And a plurality of pure oxygen or oxygen enriching burners attached to the main body case for heating the billets by colliding with a combustion flame on the entire surface and the outer surface of the billet,

The ratio D / L of the diameter D of the nozzle to the distance L from the outer surface of the billet to the nozzle of the burner is 0.04 to 0.04, the pitch P of the nozzle is 30 to 50 times the diameter D of the nozzle ,
Wherein the skid rail is hollow and has a plurality of injection holes along its longitudinal direction inserted therein and injects water supplied to the pipe from the injection hole toward an inner surface of a portion supporting the billet, .

The pure oxygen or oxygen enrichment burner is preferably a water-cooled structure.

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The skid rail preferably has a triangular cross-section.

The billet is preferably an aluminum alloy or a copper alloy.

According to the present invention, the billet is supported in the atmospheric release state to eliminate the radiated heat from the furnace wall, and the flame burned with pure oxygen or oxygen-enriched burner by pure oxygen or oxygen-enriched burner is applied to the entire surface of the billet and the outer surface The billet is heated only by the convection heat from the flame, so that the heating ability and thermal efficiency over the electromagnetic induction heating system can be achieved.

Since the burner has a water-cooled structure, it can be protected from thermal shock during heating.

Since the skid rail has a water-cooled structure, it has good durability against thermal shock, and there is no fear of spalling in the case of refractories or melting loss in the case of metal.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 and 2 show a heating apparatus for a billet W according to the present invention.

This heating apparatus has a main body case 2 provided on a mount 1. The main body case 2 has a steel frame 3 having an inverted U-shape on the loading side of the billet W and on the extraction side. A plurality of (in the embodiment, six) oxygen or oxygen-enriched burner units 4 (hereinafter, simply referred to as burner units) having a water-cooled structure are attached to the inside of these frames 3 with both ends supported. The burner units 4 are arranged at equal intervals (equidistant intervals) in the circumferential direction and extend in the longitudinal direction of the main body case 2, that is, toward the extraction side from the charging side. There is no furnace wall in the main body case 2, and the inside and outside are communicated, and the burner unit 4 is attached in an atmospheric release state. On both sides of the burner unit 4 at the lowermost position, a pair of skid rails 5 for supporting the billet W is provided extending from the loading side to the extraction side.

A loading door 6 and a pusher 7 are provided on the loading side of the main body case 2. The loading door 6 can be raised and lowered by a lifting cylinder 8. The pusher 7 can load the billet W into the main body case 2 through the skid rail 5 and transport it toward an extruder (not shown) on the extraction side. On the extraction side of the main body case 2, an extracting door 9 is provided so as to be movable up and down by an elevating cylinder 10. An exhaust port (11) communicating with the inside of the main body case (2) is formed in the extraction door (9).

As shown in Fig. 3 (a), the burner unit 4 is formed with a plurality of flame spray nozzles 12 in a predetermined arrangement and pitch. The arrangement of the nozzles 12 is an equilateral triangle, but is not limited thereto. Each burner unit 4 is divided into a plurality of heating zones (four zones A to D in the embodiment) in the longitudinal direction, and the combustion capacity can be adjusted independently for each heating zone.

The convective average heat transfer coefficient Hcm of the combustion flame from the plurality of burner units 4 is set to P (m), the nozzle diameter D (m) when the discharge flow rate of the nozzle 12 is constant, , L (m) is the distance from the outer peripheral surface of the billet to the nozzle 12 of the burner unit 4, and k is an integer.

(Equation 1)

Hcm = k × 1 / P ^{0 .375} × D / L

The inventors carried out experiments to determine the optimal nozzle pitch P, the nozzle diameter D, and the distance L from the outer circumferential surface of the billet to the nozzle 12 based on Equation (1). As a result, the ratio D / L of the nozzle diameter D to the distance L from the outer surface of the billet W to the nozzle 12 is 0.02 to 0.04. When the D / L is 0.02 or less, the heating is insufficient and the heating ability equivalent to the electromagnetic induction heating can not be obtained. When D / L is 0.04 or more, the portion of the billet W directly contacting the flame is subjected to melting loss. On the other hand, the nozzle pitch P is set to 30 to 50 times the nozzle diameter D This is determined in order to satisfy both of the heating time and the thermal efficiency corresponding to the electromagnetic induction heating system, and is most preferably 40 times. For example, when the nozzle diameter D is 1 mm, the nozzle pitch P is 40 mm, and when the nozzle diameter D is 0.5 mm, the nozzle pitch P is 20 mm. The nozzle diameter D ranges from 1.0 mm to 0.5 mm. If it is 1.0 mm or more, the thermal efficiency becomes 37.1% or less, and the thermal efficiency equivalent to the electromagnetic induction heating system can not be secured. When the diameter is 0.5 mm or less, drilling becomes difficult. The flow rate of the flame from the nozzle 12 can increase the convective heat transfer rate as fast as possible, but it is 200 m / s or less. When it is more than 200 m / s, the combustion noise is high and the working environment is hindered.

As shown in Fig. 4, the skid rail 5 has a triangular hollow section in cross section and a pipe 13 inserted therein. The pipe 13 is provided with a plurality of injection holes 14 in the longitudinal direction so that the water supplied to the pipe is discharged from the injection hole 14 to the right corner portion (The vertex portion) of the nozzle. The water jetted from the pipe 13 is discharged from the discharge port 15 provided on the end face of the extraction side of the skid rail 5. The skirt rail 5 is not limited to a triangular shape but may be circular, rectangular, semicircular, or elliptical. In any shape, however, the injection hole 14 may be formed in a shape that supports the billet W To the inner surface of the part.

Next, the operation of the heating apparatus constructed as described above will be described.

The charging door 6 is opened to the lifting cylinder 8 and the billet W is charged into the main body case 2 by the pusher 7 through the skid rail 5 and then the charging door 6 is closed. The burning unit 4 is ignited by an ignition means (not shown), and the combustion capacity of the burning waterside of the burner unit 4 on the long- For example, 400 占 폚 and the temperature of the extracted single-side combustion zone is set to 500 占 폚, for example, by controlling the temperature of the inlet / outlet-side combustion zone of the billet W to be lower than the combustion capacity of the combustion zone .

Here, since the billet W is supported on the skid rail 5 in an atmospheric release state without a furnace wall, there is no radiated heat from the furnace wall. However, instead of combustion by air, a flame burned with pure oxygen or oxygen-enriched oxygen by the burner unit 4 is caused to collide with the entire surface of the billet W and the outer surface of the billet W, W), it is possible to achieve heating capability and thermal efficiency equal to or higher than that of the electromagnetic induction heating system.

Since the burner unit 4 is a water-cooled structure, it is protected from thermal shock during heating. The skid rail 5 also has a water cooling structure for supplying water to the inner surface of the right angle portion for supporting the billet W from the pipe 13 therein so that the durability against thermal shock is good, There is no fear of spoilage in the case of spalling or metal.

When the heating of the billet W is finished, the burner unit 4 is exhausted and the extracting door 9 is opened to the elevating cylinder 10 to push the heated billet W to the pusher 7 to the extruder disposed on the downstream side. Thereafter, the above described processing is intermittently executed.

Next, an experimental example relating to a heating apparatus for a billet (W) of the present invention will be described.

Six burner units 4 (4a to 4f) divided into four heating zones in the longitudinal direction A to D are arranged in the circumferential direction by 45 mm apart from the outer peripheral surface of the billet W of? 156 × 400 ^L Respectively.

The specifications of the burner unit 4 and the combustion capacity for each heating area are shown in Tables 1 and 2.

(Table 1)

Oxygen or oxygen enrichment burner unit specification

  Burner length    490mm   Number of nozzles    28 holes   Number of burners    6   fuel    LPG   Low calorific value 91 MJ / m ³ [nor] (21800 kcal / m ³ [nor])   Theoretical oxygen content 5.0 m ³ / m ³ [nor]   Oxidant    Pure oxygen (supplied from bomb)   Oxygen ratio    1.0 or 1.1   Cooling water flow rate 5 m ³ / h [nor] at 0.2 MPa

(Table 2)

The combustion capacity for each heating region of the burner unit

Zone      A      B      C      D     Sum Number of nozzles 4 holes × 6 units 8 holes × 6 units 8 holes × 6 units 8 holes × 6 units 28 holes × 6 units Combustion capacity
MJ / h     209     418     418     418     1463

Experimental example (1) in Table 3 is an example of heating the billet (W) at room temperature (30 占 폚) to 500 占 폚 and confirming the heating ability and thermal efficiency at that time. As shown in the following table, in the present invention, 37.1% is the method of impinging the high-temperature combustion flame injected from the burner unit 4 on the entire surface of the billet W and the outer surface of the billet W The billet W can be heated to 500 占 폚 in 79 seconds with a high thermal efficiency (heat reception amount / heat input amount).

(Table 3)

Heating capacity test 1

Combustion capacity
(MJ / h) heating
time input
calorie Heating rate Calories Thermal efficiency  A  B  C  D Sum  second  MJ   ℃  MJ   % Experimental Example (1) 209 418 418 418 1463  79 32.1   470 11.9   37.1

Heat input = combustion capacity × heating time

Heat quantity of water = temperature increase × average specific heat × billet weight

Experimental example (2) shown in Table 4 shows an experimental example in which oblique heating is performed on billet (W) preliminarily heated to 250 占 폚. This is an experiment in which it is assumed that the billet W carried by the continuous casting machine is to be obliquely heated. In the four heating zones A to D of the burner unit 4, B to D are ignited and only A As a result of heating without ignition, the temperature difference? T = 73 占 폚 / 400 mm between the front end portion and the rear end portion of the billet W at a heating time of 43 seconds and converted into a billet W of 1000 mm , The inclined heating is performed at an ideal temperature gradient (100 DEG C / 1000 mm) or more.

(Table 4)

Gradient heating test 2

Combustion capacity
(MJ / h) heating
time Early
Temperature Rear end
Temperature Front end portion
Temperature Temperature difference  A  B  C  D Sum  second  ℃   ℃   ℃   ℃ Experimental Example (2)  0 418 418 418 1254  43  255   419   492    73 Experimental Example (3)  0 418 418 418 1254  76   30   343   449   106

Experimental example (3) in Table 4 shows experimental examples in which the billet W at room temperature is subjected to oblique heating. As a result, the temperature difference DELTA T between the front end portion and the rear end portion of the billet W at room temperature was 76 seconds and the temperature difference DELTA T was 106 DEG C / 400 mm. As a result, W), this test also shows that the temperature is obliquely heated by an abnormal temperature gradient (100 DEG C / 1000 mm) or more.

Thus, according to the heating apparatus of the present invention, since the high temperature combustion flame using pure oxygen or oxygen-enriched air collides with the outer surface of the billet (W) It is possible to heat the billet to the extrusion molding temperature in a short period of time from the cold material) and to easily perform the inclined heating only by controlling the burning capacity of the burner unit in the longitudinal direction of the billet W Proved.

1 is a sectional view of a billet heating apparatus according to the present invention;

2 is a sectional view taken along the line II-II in Fig.

Fig. 3 is a front view (a) showing the nozzle arrangement of the burner unit, and Fig. 3 is a cross-sectional view showing the arrangement of the burner unit and the skid rail.

4 is a cross-sectional view (a) and a longitudinal section view (b) of the skid rail.

DESCRIPTION OF THE REFERENCE NUMERALS

2: Body case

3: Frame

4: Burner unit

5: Skid rail

12: Nozzle

13: Pipe

14:

W: billet

Claims (5)

A main body case made of a frame in which a furnace wall is not provided but which is communicated with the inside and outside, A skid rail for supporting a billet charged in the main body case to an atmospheric release state, A plurality of pure oxygen or oxygen enrichment burners attached to the body case for heating the billets by colliding a combustion flame against an outer surface extending over the entire length and the entire circumference of the billet, Lt; / RTI & Wherein the ratio D / L of the diameter D of the nozzle to the distance L from the outer surface of the billet to the nozzle of the burner is 0.02 to 0.04 and the pitch P of the nozzle is D To 30 times, Wherein the skid rail is hollow and has a plurality of injection holes along the longitudinal direction thereof inserted therein and injects water supplied to the pipe from the injection hole toward the inner surface of the portion supporting the billet, And discharging the billet from an outlet provided in an end surface of the skid rail. The billet heating apparatus according to claim 1, wherein the pure oxygen or oxygen enriched burner has a water-cooled structure. 2. The billet heating apparatus according to claim 1, wherein the skid rail has a triangular cross-section. The billet heating apparatus according to claim 3, wherein the billet is an aluminum alloy or a copper alloy. delete

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