JP2007313546A - Heating furnace for extrusion die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To employ heating apparatuses having maximum heating temperatures higher than that of an electric heater and generating radiation heat, in a heating furnace for an extrusion die. <P>SOLUTION: The heating furnace for the extrusion die is provided with heating apparatuses 8 for heating the extrusion die 4 in a furnace body 1. Radiant tubes are used for the heating apparatuses 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heating furnace for an extrusion die used for, for example, aluminum extrusion.

Extrusion dies are preheated in a heating furnace before extrusion, set in the extruder at the time of extrusion, and then relatively pushed into billets to pass through the die holes to be used to produce the desired shape. It is done. A conventional heating furnace using an electric furnace is known (Patent Document 1).
Japanese Patent Laid-Open No. 5-31528, (sentence in paragraph number 0016)

  By the way, for example, when preheating a steel die, as shown in FIG. 3, the furnace atmosphere temperature is raised to the furnace use limit temperature of about 550 ° C. in the initial stage, and 550 ° C. is increased in the middle stage. The die is kept at a temperature suitable for extrusion by holding for a certain period of time and holding the atmosphere temperature in the furnace at about 450 ° C. in the latter stage, and about 4.5 hours as a whole. Therefore, if the time until the temperature is first raised to 550 ° C. can be shortened, the preheating time as a whole can be shortened. For this purpose, the electric heater of the electric furnace may be operated at as high a temperature as possible in the initial stage of preheating. However, the electric heater has a maximum temperature of about 800 ° C. because of its characteristics. Therefore, the difference between the maximum temperature and the furnace atmosphere temperature is small, and the furnace atmosphere temperature is difficult to reach 550 ° C.

  In addition, an electric heater is used in the heating device for an extrusion die heating furnace (electric furnace) because the air inside is heated by radiant heat, and the die is cleaned by circulating the heated air. This is because there is utility such as prevention.

  The present invention has been created in consideration of the above-mentioned circumstances, and the problem to be solved is to use a heating device that generates radiant heat at the highest temperature as compared with an electric heater in an extrusion die heating furnace.

  The present invention is characterized in that a radiant tube is used as a heating device in an extrusion die heating furnace provided with a heating device for an extrusion die in the furnace body.

  The radiant tube generates radiant heat, so it does not generate wrinkles like a burner. Therefore, when used in the heating device of an extrusion die heating furnace, the extrusion die does not become dirty and does not oxidize, and the maximum temperature Is about twice that of an electric heater, so that the time required to reach the desired furnace temperature can be shortened.

  As shown in FIG. 1 and FIG. 2, the extrusion die heating furnace is provided with a part of the furnace body 1 surrounding the periphery, ceiling and floor, for example, a front opening 2 that can be opened and closed by a door 3. Insert and remove the die 4 for use. In order to put it in and out, a table 5 on which the extrusion die 4 is placed is provided on the floor 6 at a substantially central portion in the furnace body 1, and the floor 6 can be moved along a rail 7 laid therebelow. It is provided. Further, a plurality of radiant tubes 8 as heating devices 8 of the extrusion die 4 are arranged at intervals in the front and rear sides inside the left and right inner wall surfaces of the furnace body 1, and further inside the left and right radiant tubes 8. A shielding plate 9 is provided.

  The shielding plate 9 is provided over a range from the inner wall front surface of the furnace body 1 to the rear surface of the inner wall to prevent the radiant heat from the radiant tube 8 from being directly applied to the extrusion die 4, and the floor 6 The space | interval which becomes the path | routes 10 and 11 of hot air with respect to the ceiling is opened. In order to provide the passages 10 and 11, the left and right shielding plates 9 are provided with reinforcing bars 12 between the upper portions thereof, and the reinforcing bars 12 are suspended from the ceiling of the furnace body 1 through the pipes 13. Is supported by floating from the floor 6. On the other hand, on the ceiling of the furnace body 1, a fan 14 is provided at a position corresponding to the position immediately above the extrusion die 4, and the shielding plate is used by the wind from the fan 14 and using the upper and lower passages 10 and 11 of the shielding plate 9. 9 generates a convection of hot air that circulates in and out of the inside of the furnace body 1 to keep the atmosphere inside the furnace body 1 uniform. Reference numeral 15 denotes a bearing mechanism of the fan 14, and reference numeral 16 denotes a drive unit (motor or the like) of the fan 14.

  The radiant tube 8 is concentrically arranged with the end of the outer tube closed, burns fuel in the inner tube, and discharges exhaust gas from the gap between the inner tube and outer tube to the root side of both tubes. It is guided and discharged out of the furnace body 1, and the maximum temperature is about 1700 ° C. When the extrusion die 4 is heated, as shown in FIG. 3, heating is started immediately after the extrusion die 4 is charged by a control unit (not shown). In the initial stage, the radiant tube 8 can be set to 1700 ° C. as much as possible. The inside of the furnace body 1 is heated close to the furnace so that the temperature inside the furnace is slightly higher than the target temperature, for example, 550 ° C., and finally the extrusion die 4 is brought to the target temperature, for example, about 450 ° C. When stabilized, the extrusion die 4 is extracted (discharged) from the furnace body 1, but the series of heating times can be shortened.

  In addition, when the current unit price of liquefied natural gas and electric power is reflected, the running cost is about 1/3 to 1/4 when the radiant tube 8 is used and when the electric heater is used.

  The die heating furnace for extrusion is not limited to the above embodiment. For example, the radiant tube 8 is suspended from the ceiling in a vertical state along the vertical direction, but may be provided in a horizontal state along the front-rear direction. The radiant tubes 8 may be provided outside the shielding plate 9 in two rows with a left and right spacing.

It is a longitudinal cross-sectional view of the front direction which shows the die heating furnace for extrusion of this invention. It is a longitudinal cross-sectional view of the side direction which shows the die heating furnace for extrusion of this invention. It is a graph which shows time transition with the atmosphere temperature in a furnace, and the temperature of the die for extrusion.

Explanation of symbols

1 furnace body, 2 openings, 3 doors, 4 extrusion dies, 5 units, 6 floors, 7 rails, 8 heating devices,
8 radiant tubes, 9 shielding plates, 10 passages, 11 passages, 12 reinforcing bars, 13 pipes,
14 fans, 15 bearing mechanism, 16 drive unit

Claims (1)

In the extrusion die heating furnace provided with the heating device (8) of the extrusion die (4) in the furnace body (1),
A die heating furnace for extrusion, wherein a radiant tube is used for the heating device (8).

Images