Walking-beam type heating furnace

Abstract

In a heating furnace 10 where elongate workpieces fed into the heating furnace are sequentially transferred on fixed beams by walking beams from an inlet area to an outlet area, concaves to retain the workpieces are formed at least on the walking beams. A concave in the inlet area for heating the workpieces is increased in width in a transfer direction, while a concave in the outlet area where the heated workpieces are wholly heated to a uniform temperature and retained in position is formed in a corrugated configuration. Despite curving of an elongate workpiece being heat treated as transferred by walking beams in a direction crossing a longitudinal direction of the workpiece, this ensures that the curved workpiece is properly transferred and adequately corrected for the curving.

Claims

1. A walking-beam type heating furnace comprising fixed beams which retain workpieces fed into the heating furnace and are laid in a furnace length direction, and walking beams which sequentially transfer said workpieces on the fixed beams from an inlet area to an outlet area and are laid in the furnace length direction, wherein for said walking beams to transfer elongate workpieces placed in a direction crossing a transfer direction, concaves to retain said elongate workpieces are formed at least on said walking beams, and wherein the concaves on the walking beams in the inlet area for heating the workpieces fed into the heating furnace have a flat horizontal bottom surface with two vertical sides and are increased in width in the transfer direction to ensure that a workpiece curved in the transfer direction crossing the longitudinal direction thereof is out of contact with a workpiece retained in the adjoining concave, while the concaves on the walking beams in the outlet area allowing the heated workpieces to be wholly heated to a uniform temperature and retained in position are formed in a corrugated configuration.

2. The walking-beam type heating furnace according to claim 1, wherein said workpiece is an elongate tubular member.

3. The walking-beam type heating furnace according to claim 1, wherein the concave formed on said inlet-side walking beam has a greater width in the transfer direction than that of the concave formed on said outlet-side walking beam.

4. The walking-beam type heating furnace according to claim 1, wherein the corrugated concave formed on said outlet-side walking beam has a V-groove corrugated configuration.

5. The walking-beam type heating furnace according to claim 1, wherein a pitch between the concaves formed on said outlet-side walking beam is smaller than a pitch between the concaves formed on said inlet-side walking beam, and wherein a distance that the outlet-side walking beam reciprocally moves in the transfer direction of the workpiece is shorter than a distance that the inlet-side walking beam reciprocally moves in the transfer direction of the workpiece.

6. The walking-beam type heating furnace according to claim 1, wherein said fixed beams are formed with concaves to retain said workpieces, and wherein the concave formed on the fixed beam in the inlet area for heating the workpiece fed into the heating furnace and the concave formed on the fixed beam in the outlet area allowing the heated workpiece to be wholly heated to the uniform temperature and retained in position are in correspondence to the concaves formed on said walking beams.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic cross-sectional view of a walking-beam type heating furnace according to one embodiment of the invention taken along the longitudinal line of the furnace;

(2) FIG. 2 is a schematic vertical sectional view of the walking-beam type heating furnace of the above embodiment taken along the width line of the furnace;

(3) FIG. 3 is a fragmentary explanatory diagram of the walking-beam type heating furnace according to the above embodiment in which walking beams are divided into inlet-side walking beams and outlet-side walking beams, and concaves formed on the inlet-side walking beams and concaves formed on the outlet-side walking beams have different configurations;

(4) FIG. 4 is a fragmentary explanatory diagram of the walking-beam type heating furnace according to the above embodiment in which concaves formed on inlet-side fixed beams and concaves formed on outlet-side fixed beams have different configurations;

(5) FIG. 5 is a fragmentary explanatory diagram of the walking-beam type heating furnace according to the above embodiment in which workpieces composed of an elongate tubular member are transferred by the walking beams from an inlet area to an outlet area of the heating furnace;

(6) FIG. 6 is a fragmentary explanatory diagram of a fixed beam of the walking-beam type heating furnace according to the above embodiment, on which an outlet-side concave formed in a V-groove corrugated configuration and adjoining an inlet-side flat-bottomed concave increased in width in a transfer direction has an upstream-side slope increased in length;

(7) FIG. 7 is a fragmentary explanatory diagram showing an exemplary modification of the walking-beam type heating furnace according to the above embodiment, in which the walking beam is not divided and the concaves on the inlet side and the outlet side of the walking beam have the same pitch but are only varied in configuration; and

(8) FIG. 8 is a fragmentary explanatory diagram of the walking-beam type heating furnace according to the above exemplary modification, in which the concaves on the inlet side and the outlet side of the fixed beam have the same pitch but are only varied in configuration.

BEST MODES FOR CARRYING OUT THE INVENTION

(9) A walking-beam type heating furnace according to an embodiment of the invention will hereinbelow be described in detail with reference to the accompanying drawings. It is to be noted that the walking-beam type heating furnace according to the invention is not limited to the following embodiments and the invention can be carried out in various ways without departing from the spirit and scope of the invention.

(10) In a walking-beam type heating furnace of the embodiment, as shown in FIG. 1, an inlet port 12 that allows a workpiece W composed of an elongate tubular member such as steel pipe into a heating furnace 10 is provided at an end of a side wall 11 of the heating furnace 10 in a furnace length direction, and an outlet port 13 for discharging the heat-treated workpiece W from the heating furnace 10 is provided at the other end of the side wall in the furnace length direction. The inlet port 12 and outlet port 13 are provided with opening and closing doors 12a, 13a, respectively.

(11) Carrying-in rollers 14 are provided at an area where the above-described workpiece W is fed into the heating furnace 10 in a longitudinal direction of the workpiece through the above inlet port 12. Further, carrying-out rollers 15 are provided at an area where the heat-treated workpiece W is discharged from the heating furnace 10 in the longitudinal direction of the workpiece through the above outlet port 13.

(12) In this heating furnace 10, as shown in FIG. 1 and FIG. 2, a plurality of fixed beams 20 extending in a furnace length direction, or a transfer direction of the workpiece W, are mounted on fixing supports 21 standing upright on a hearth 16 and are juxtaposed in a furnace width direction with required spacing. Further, a plurality of walking beams 30 extending in the transfer direction of the workpiece W are mounted on driving supports 31 extending upward through the hearth 16 from walking-beam driving means 40 disposed under the hearth 16 and are juxtaposed in the furnace width direction with the required spacing.

(13) The individual walking beams 30 described above are driven into walking motion by the walking-beam driving means 40. Specifically, the walking beams 30 are reciprocally moved in the vertical direction and the transfer direction of the workpiece W so that the workpieces W fed into the heating furnace 10 are sequentially transferred on the fixed beams 20 from an inlet area at the inlet port 12 to an outlet area at the outlet port 13.

(14) For the workpieces W composed of the elongate tubular member such as steel pipe to be sequentially transferred on the fixed beams 20 by the above walking beams 30, concaves 22, 32 for retaining the workpieces W are formed on the above-described fixed beams 20 and walking beams 30 respectively and are arranged in the transfer direction of the workpiece W. In this embodiment, as shown in FIG. 1 and FIG. 3, the above walking beams 30 are divided into an inlet-side walking beam 30a that allows the workpiece fed into the heating furnace 10 to be heated, and an outlet-side walking beam 30b that allows the heated workpiece to be wholly heated to a uniform temperature and retained in position.

(15) A flat-bottomed concave 32a increased in width in the transfer direction is formed on the inlet-side walking beam 30a that allows the workpiece W to be heated. On the other hand, a concave 32b having a V-groove corrugated configuration is formed on the outlet-side walking beam 30b that allows the heated workpiece W to be wholly heated to the uniform temperature and retained in position. A pitch pa between the concaves 32a on the inlet-side walking beam 30a is greater than a pitch pb between the concaves 32b on the outlet-side walking beam 30b.

(16) Also on the above-described fixed beam 20, as shown in FIG. 1 and FIG. 4, a flat-bottomed concave 22a increased in width in the transfer direction is formed in the inlet area for heating the workpieces W, just as on the above inlet-side walking beam 30a. In the outlet area where the heated workpieces W are wholly heated to the uniform temperature and retained in position, on the other hand, a concave 22b having a V-groove corrugated configuration is formed just as on the above outlet-side walking beam 30b. A pitch pa between the concaves 22a on the inlet-side fixed beam 20 is greater than a pitch pb between the concaves 22b on the outlet-side fixed beam 20.

(17) The walking-beam driving means 40 for driving the walking beams 30 into the walking motion is divided into one for the inlet-side walking beams 30a and one for the outlet-side walking beams 30b. The inlet-side walking beams 30a are driven into the walking motion by first walking-beam driving means 40a. On the other hand, the outlet-side walking beams 30b are driven into the walking motion by second walking-beam driving means 40b.

(18) A distance that the inlet-side walking beams 30a are reciprocally moved by the first walking-beam driving means 40a in the transfer direction of the workpiece W is longer than a distance that the outlet-side walking beams 30b are reciprocally moved by the second walking-beam driving means 40b in the transfer direction of the workpiece W so that the workpieces W in the concaves 32a of the inlet-side walking beams 30a may be sequentially fed into the concaves 22a of the inlet-side fixed beams 20 in an appropriate manner and that the workpieces W in the concaves 32b in the outlet-side walking beams 30b may be sequentially fed into the concaves 22b of the outlet-side fixed beams 20 in an appropriate manner.

(19) In this manner, the workpieces W composed of the elongate tubular member such as steel pipe are fed into the heating furnace 10 via the inlet port 12 and are sequentially transferred on the fixed beams 20 by the above-described inlet-side walking beams 30a and outlet-side walking beams 30b in the direction crossing the longitudinal direction of the workpiece W. In this case, as shown in FIG. 5, if the workpieces W in the inlet area become significantly curved in the direction crossing the longitudinal direction thereof due to difference in heating temperatures in the inlet area of the heating furnace 10, the curved workpieces W are properly retained in the flat-bottomed concaves 32a of the inlet-side walking beams 30a and the flat-bottomed concaves 22a of the fixed beams 20 in the inlet area, the concaves 32a, 22a having the width increased in the transfer direction. Hence, the curved workpieces W are properly transferred to the outlet area without protruding into the adjoining concaves 22a to collide against or overlap with the adjoining workpieces W. During the course of transfer of the curved workpieces W to the outlet area, the whole bodies of the above workpieces W so curved are gradually heated so that the workpieces W are gradually decreased in the curving.

(20) The workpieces W thus decreased in the curving are sequentially transferred on the fixed beams 20 in the outlet area by the outlet-side walking beams 30b. In this process, the above-described second walking-beam driving means 40b transfer the above workpieces W little by little via the narrow-pitched concaves 32b on the outlet-side walking beams 30b and the narrow-pitched concaves 22b on the fixed beams 20 in the outlet area. In addition, the above workpieces W progressively rotate in the V-groove corrugated concaves 32b on the outlet-side walking beams 30b and the V-groove corrugated concaves 22b on the fixed beams 20 in the outlet area, so that the whole bodies of the workpieces W are uniformly heated. The workpieces W are adequately corrected for the curving so as to be properly heat treated. Thus, the heat-treated workpieces W in straightened form can be discharged from the above outlet port 13.

(21) In order to ensure that the workpiece W retained in the flat-bottomed concave 32a of the inlet-side walking beam 30a, which is increased in width in the transfer direction, is properly fed into the V-groove corrugated concave 22b of the fixed beam 20 in the outlet area, it is preferred in the above embodiment, as shown in FIG. 6, that the V-groove corrugated concave 22b of the outlet-side fixed beam 20 which adjoins the flat-bottomed concave 22a increased in width in the transfer direction and formed on the inlet-side fixed beam 20 has an upstream-side slope A increased in length.

(22) In the walking-beam type heating furnace according to the above embodiment, the walking beams 30 are divided into the inlet-side walking beam 30a and the outlet-side walking beam 30b and the pitch pa between the concaves 32a on the inlet-side walking beam 30a is greater than the pitch pb between the concaves 32b on the outlet-side walking beam 30b. Alternatively, as shown in FIG. 7, the walking beams 30 may not be divided while the concaves 32a, 32b formed on the inlet side and the outlet side of the walking beam 30 may have the same pitch p. Only the configuration may be varied between the concaves 32a, 32b on the inlet side and outlet side of this walking beam 30. Further, the walking beams 30 may be driven into the walking motion by one walking-beam driving means 40. In this case, as shown in FIG. 8, the concaves 22a, 22b formed on the inlet side and the outlet side of the fixed beam 20 may have the same pitch p but be varied only in the configuration so as to correspond to those of the above walking beam 30.

(23) In the case where the heating furnace has this structure, the walking-beam driving means 40 can be unified because there is no need for providing the first walking-beam driving means 40a, the second walking-beam driving means 40b and the mechanism for varying the distance of reciprocal movement of the walking beam 30 in the transfer direction of the workpiece W between the inlet-side walking beam 30a and the outlet-side walking beam 30b. In this structure, however, the workpiece W in the outlet area of the heating furnace 10 is transferred at the same pitch as in the inlet area. It is therefore preferred to take a measure such as to increase the length of the outlet area of the heating furnace 10 in order to secure adequate time to achieve uniform heating of the workpieces W.

REFERENCE SIGNS LIST

(24) 10: HEATING FURNACE 11: SIDE WALL 12: INLET PORT, 12a: OPENING AND CLOSING DOOR 13: OUTLET PORT, 13a: OPENING AND CLOSING DOOR 14: CARRYING-IN ROLLER 15: CARRYING-OUT ROLLER 16: HEARTH 20: FIXED BEAM 21: FIXING SUPPORT 22: CONCAVE, 22a: INLET-SIDE CONCAVE, 22b: OUTLET-SIDE CONCAVE, A: SLOPE 30: WALKING BEAM, 30a: INLET-SIDE WALKING BEAM, 30b: OUTLET-SIDE WALKING BEAM 31: DRIVING SUPPORT 32: CONCAVE, 32a: INLET-SIDE CONCAVE, 32b: OUTLET-SIDE CONCAVE 40: WALKING-BEAM DRIVING MEANS, 40a: FIRST WALKING-BEAM DRIVING MEANS, 40b: SECOND WALKING-BEAM DRIVING MEANS p: PITCH BETWEEN CONCAVES, pa: PITCH BETWEEN INLET-SIDE CONCAVES, pb: PITCH BETWEEN OUTLET-SIDE CONCAVES W: WORKPIECE