JPH0920925A - Hollow steel pipe heating equipment - Google Patents

Abstract

(57) Abstract: A heating apparatus for a hollow steel pipe is provided, which can suppress the flow of flame toward a carry-in port, a carry-out port, a smoke exhaust port, and the like, and can uniformly heat the hollow steel pipe. SOLUTION: The hollow steel pipe 1 carried into a heating furnace 21 is heated at a high temperature by the combustion heat of heating burners 33, 35 while being supported and conveyed by a roller 41 of a roller conveyor 40. heating furnace
When the hollow steel pipe 1 is being heated at 21 and the opening / closing doors 28 and 29 of the carry-in port 26 and the carry-out port 27 are opened, the flame from the heating burners 33 and 35 causes the carry-in port 26 side and the carry-out port 27. The flames from the heating burners 33 and 35 again try to flow to the side, but the smoke exhaust port 37
Although they tend to flow to the side, these flows can be suppressed by the heat shield walls 38 located in front of and behind the roller 41. It is possible to prevent the flames from the heating burners 33 and 35 from directly hitting the rollers 41, further prevent the heat from flowing out, and suppress the disturbance of the temperature in the furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow steel pipe, which is used for manufacturing a large-diameter steel pipe having a rectangular shape or a rectangular parallelepiped shape, which is used, for example, as a pillar material for construction. The present invention relates to a heating facility for a hollow steel pipe that is transported and loaded into a heating furnace, heated to a high temperature during transportation in the heating furnace, and then discharged from the heating furnace.

[0002]

2. Description of the Related Art Conventionally, large-diameter square steel pipes used for building pillars and the like have been obtained by the manufacturing method disclosed in Japanese Patent Publication No. 58-13245. That is, in this conventional method, one thick steel plate is transferred in the length direction to perform groove forming on both sides, and then a press is used to bend the portions corresponding to the four corners of the square steel pipe to form a square steel pipe. While forming into an approximate shape, then passing the approximate square steel pipe through multiple stages of forming rolls into a rectangular steel pipe shape, temporarily welding the groove abutting faces sequentially, and then welding the inner and outer surfaces of the groove member by automatic welding After that, strain relief is performed to obtain a large-diameter square steel pipe.

However, according to the large-diameter rectangular steel pipe manufactured by the cold forming described above, the hardness of the corner portion and the seam welded portion is considerably higher than that of the flat plate portion (base material).
Yield strength of the corners and seam welds increases, leading to a decrease in ductility. As a result, the mechanical properties are non-uniform and residual stress is generated, making it difficult to perform cutting, etc. .

Therefore, recently, a round steel pipe having a predetermined diameter, plate thickness and length commensurate with a large-diameter rectangular steel pipe is used as a raw pipe, and the raw pipe is heated by the combustion heat of a heating burner in a heating furnace and then heated. It is provided that a raw pipe is hot-formed in a round steel pipe forming mill to be a refined raw pipe, and the refined raw pipe is hot-formed in a square steel pipe forming mill to produce a large-diameter square steel pipe.

[0005]

However, in the above-mentioned manufacturing method using the round steel pipe as the raw pipe, when the opening / closing doors of the carry-in port and the carry-out port formed in the heating furnace are opened, they are placed in the vicinity of the open / close door. The flame from the installed heating burner flows to the carry-in side and the carry-out side, and the flame from the heating burner arranged near the smoke exhaust port formed in the heating furnace is the smoke exhaust port side. Will flow to. As a result, the flame from the heating burner directly hits the roller and becomes hot, resulting in damage to the roller. In addition, the heat efficiency is lowered due to the outflow of heat, and the temperature inside the roller is disturbed, so that the original pipe is not heated uniformly in the circumferential direction and the length direction. When the raw pipe is not heated uniformly as described above, the raw pipe may be bent.

Therefore, in the invention according to claim 1 of the present invention, the heating of the hollow steel pipe which can suppress the flow of flame toward the carry-in port, the carry-out port, the smoke exhaust port, etc. and can uniformly heat the hollow steel pipe The purpose is to provide facilities.

[0007]

In order to achieve the above-mentioned object, the heating equipment for a hollow steel pipe according to claim 1 of the present invention has a hollow steel pipe which is conveyed in its lengthwise direction to a heating furnace. A heating facility for hollow steel pipes that is carried in and heated to a high temperature by the combustion heat of a heating burner during transportation in this heating furnace, and then carried out from the heating furnace. In addition to the above, the opening and closing doors are provided at the carry-in port and the carry-out port, respectively, and a roller conveyor for conveying the hollow steel pipe is provided in the heating furnace, and a heat shield wall is provided at a predetermined position between the rollers of the roller conveyor. It is characterized by being provided.

Therefore, according to the first aspect of the invention, the hollow steel pipe carried into the heating furnace is supported by the roller group of the roller conveyor and conveyed in the heating furnace, and is heated to a high temperature by the combustion heat of the heating burner during the conveyance. You can Then, when the hollow steel pipe is being heated in the heating furnace, when the opening / closing doors of the carry-in port and the carry-out port are opened, the flame from the heating burner arranged in the vicinity of these opens the carry-in side and the carry-out port. The flame from the heating burner installed near the smoke exhaust port tries to flow to the smoke exhaust port side, but these flows are the heat shields located before and after the roller. It can be suppressed by the wall. Therefore, it is possible to prevent the flame from the heating burner from directly hitting the roller, further prevent the heat from flowing out, and suppress the disturbance of the temperature in the furnace.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 7, when manufacturing a large-diameter square steel pipe, for example, a round hollow steel pipe having a predetermined diameter, plate thickness, and length commensurate with the large-diameter square steel pipe is used as the raw pipe 1.
Be prepared on the loading floor 10 as. Here, the raw pipe 1 is manufactured in a state having the seam welded portion 2 by high-frequency welding, arc welding or the like, but this may be a seamless raw pipe 1. The loading floor 10 is of a conveyor type, and supports a plurality of raw tubes 1 in parallel and transports them in a direction transverse to the length direction.

The raw pipe 1 transferred to the end of the loading floor 10 is
It is carried into the heating equipment 20, is transported in the lengthwise direction in the heating equipment 20, and is heated to a high temperature during the transportation. The raw tube 1 heated to a predetermined temperature is carried out of the heating equipment 20,
Then, the welding seam position adjusting device 11 is delivered.

This welding seam position adjusting device 11 is composed of a support roll 12, a press roll 13, etc., and the raw pipe 1 is rotated around the pipe axis center via these rolls 12, 13.
The position of the seam weld 2 is aligned in a fixed direction. This fixed direction is the position where the seam welded portion 2 is always present near the center of the flat plate portion when the final large-diameter square steel pipe is obtained. In addition, when the seamless raw tube 1 is transported,
This part of the welding seam position adjusting device 11 is passed, and when only the seamless original pipe 1 is used, the process by the welding seam position adjusting device 11 is deleted.

Raw pipe 1 from welding seam position adjusting device 11
Is carried into the round steel pipe forming mill 14. Here, the raw pipe 1 is hot-formed into a drawing shape through a plurality of sizing rolls 15 and the like, and the raw pipe 1 is given a predetermined size so that the final large-diameter rectangular steel pipe (product) is finished with a given size. Purify to diameter. The required number of descaler devices 16 are provided around the round steel pipe forming mill 14 (required positions before and after the round steel pipe forming mill 14, only in front, only behind, between stands, etc.). This descaler device 16 is used for the refined raw tube 1.
A water is applied to A to spray water, and this water spray can remove mill scale and improve the surface texture.

The refined raw pipe 1A thus refined by the round steel pipe forming mill group 14 is carried into the square steel pipe forming mill 17. Here, the final hot forming (forming temperature A ₃ transformation point or higher) is performed through a plurality of stencil-shaped rolls 18 and the like, and at that time, the large-diameter rectangular steel pipe 3 immediately after hot forming is The part is formed in an outward arc surface along the joining surface.

Next, the hot-formed large-diameter rectangular steel pipe 3 is
Received in the cooling floor 19. This cooling floor 19 is of a conveyor type and supports a plurality of large-diameter rectangular steel pipes 3 in parallel,
Then, it is conveyed laterally with respect to the length direction. During the transportation on the cooling floor 19, the large-diameter rectangular steel pipe 3 is gradually cooled by the air cooling system. Due to this slow cooling, each flat plate portion of the large-diameter rectangular steel tube 3 is contracted so that the arcuate surface becomes a straight surface, and the R of the corner portion becomes sharp and the section modulus becomes high.

The large-diameter square steel pipes 3 groups are transported on the cooling floor 19
The large-diameter square steel pipes 3 adjacent to each other are conveyed in a separated state, or the large-square steel pipes 3 adjacent to each other are brought into contact with each other and clamped from both sides. As a result, large-diameter square steel pipe 3
Will be gradually cooled under the same ambient temperature, so that bending during cooling can be reduced. The large-diameter rectangular steel pipe 3 that has reached the end of the cooling floor 19 is conveyed to a straightening device, a tip cutting device, a rear end cutting device, a cleaning device, and a rust preventive device, which are not shown, and processed by each of them, and then the product. Is stored as.

As described above, hot forming is performed from a round tube to a square tube, and at that time, the heating equipment 20 includes a heating furnace 21 and a heating furnace 21.
A roller conveyor 40 for conveying a hollow steel pipe arranged in the heating furnace 21, a carry-in conveyor 60 for carrying the raw pipe 1 from the loading floor 10 into the heating furnace 21, and a raw pipe 1 from the heating furnace 21.
It is configured by a carry-out conveyor 61 and the like for carrying out the work.

As shown in FIGS. 1 to 5 and 7, the heating furnace 21 is a divided furnace body divided into a plurality of pieces in the length direction thereof.
Each of the divided furnace bodies 22 is composed of an assembly of 22 and each divided furnace body 22 has an inverted U-shaped upper furnace portion 22A and this upper furnace portion 22 in a longitudinal front view.
It is formed by left and right side furnace parts 22B extending downward from both lower ends of A, and a downward convex arcuate lower furnace part 22C located between the lower ends of these side furnace parts 22B. Here, the left and right side furnace parts 22B and the lower furnace part 22C are integrated, and the lower furnace part 22C is supported on the floor side via a base frame 23.

A heating furnace formed by the group of divided furnace bodies 22
In FIG. 21, both ends in the front-rear direction are closed by end furnace walls 24 and 25, and a through hole provided in these end furnace walls 24 and 25 provides a carry-in port 26 on the upper side (front end side) and a lower side. The carry-out port 27 is formed on the side (rear end side). Further, opening / closing doors 28 and 29 are provided at the carry-in entrance 26 and the carry-out exit 27, respectively.

The left and right side furnace sections 22B are formed at predetermined intervals by a block body 30.
Is configured so that it can be inserted into and removed from the side furnace portion 22B in the left-right direction. Then, it is constructed so that no gap is created when it is inserted. Through holes 31 are formed in each block body 30, and the rollers of the roller conveyor 40 described later are arranged through the through holes 31. At that time, the through holes 31 are formed at two positions in the front-rear direction with respect to one split furnace body 22,
Based on this, a plurality of rollers are arranged at a predetermined pitch P in the front-rear direction.

A lower heating burner 33 is arranged at the lower part of one side of the heating furnace 21 and at an intermediate position between the rollers of the roller conveyor 40. That is, mounting holes 34 are formed in the group of side furnace parts 22B on the left and right sides so as to be located between the above-mentioned block bodies 30, and a lower heating burner 33 is arranged by utilizing these mounting holes 34. There is. At that time, the mounting hole 34
The axial center of is set slightly lower than the axial center of the through hole 31.

Then, in the upper part on the other side of the heating furnace 21 and in the position facing the lower heating burner 33 in a staggered manner,
An upper heating burner 35 is provided. That is, the through hole 31 is formed in the other left and right parts of the upper furnace part 22A.
A mounting hole 36 is formed so as to be located right above, and the upper heating burner 35 is disposed by utilizing this mounting hole 36. In the divided furnace body 22 adjacent to the carry-out port 27, a vertical smoke exhaust port 37 is formed in the lower furnace part 22C.

Further, heat shield walls 38 are provided at predetermined positions between the rollers of the roller conveyor 40. This heat shield wall 38
For example, it is formed by stacking refractory bricks from the lower furnace part 22C. At that time, the heat shield wall 38 is arranged at two positions between the front and rear rollers and so that the lower heating burner 33 faces between the heat shield walls 38. Heating furnace by above 22-38
21 are composed.

The roller conveyor 40 has a plurality of rollers 41 arranged at a predetermined pitch P in the front-rear direction. That is, as shown in FIGS. 1 to 5, each roller 41 includes a cylindrical roller shaft portion 42, a hollow steel pipe support portion 43 fitted onto the roller shaft portion 42, and both ends of the roller shaft portion 42. It is configured by an integrated roller bearing portion 44 and the like. The outer surface of the hollow steel pipe support portion 43 is formed as a recessed support surface 46 in the direction of the roller shaft center 45. The roller 41 is configured by the above 42 to 46.

The roller 41 is disposed through the roller bearing portion 44 in the through hole 31 of the side furnace portion 22B described above, and the roller bearing portion 44 protruding outward is a pair of bearing devices.
It is supported on the base frame 23 side via 47. Here, the roller bearing portion 44 on the other side is interlocked with a rotary drive device (motor or the like) 49 via a coupling 48 or the like, and these rotary drive device 49 groups are configured to be synchronously driven. The heat shield wall 38 is a recessed support surface of the hollow steel pipe support portion 43.
It is formed such that its upper surface is slightly lower than 46.

As shown in FIGS. 1, 4, and 6, a smoke exhausting device 50 connected to the smoke exhaust port 37 is provided. That is, the main flue 51 is formed in the floor on the side of the heating furnace 21, and the starting end of the main flue 51 is connected to the smoke exhaust port 37 via the first smoke pipe 52. A second smoke pipe 53 is connected to the end of the main flue 51, and the second smoke pipe 53 is connected to the lower part of the chimney 55 via a fan 54. A damper 56 is provided in the middle of the second smoke pipe 53, and the operation of the damper 56 controls the atmospheric pressure in the heating furnace 21 to be lower than the atmospheric pressure. A smoke exhaust device 50 is configured by the above 51 to 56.

A heat exchanger 58 is provided in the main flue 51, and the air that has exchanged heat with the exhaust gas therein is supplied to the burners 33 and 35 through a pipe group 59. The carry-in conveyor 60
Is to transfer the raw pipe 1 from the loading floor 10 to the roller conveyor 40, and the carry-out conveyor 61 is to receive the raw pipe 1 from the roller conveyor 40. Here both conveyors 6
0 and 61 are configured by a roller type or the like.

The operation of the heating equipment 20 in the above embodiment will be described below. Loading floor 10 to loading conveyor 60
The opening / closing door 28 of the carry-in port 26 is opened immediately before the raw pipe 1 conveyed via the carry-in port 26 reaches the carry-in port 26. Then, the raw pipe 1 is carried into the heating furnace 21 through the carry-in port 26 and is supported by the group of rollers 41 of the roller conveyor 40. That is, the raw pipe 1 is supported and conveyed via the recessed support surface 46 of the group of rollers 41, and when the terminal end is completely carried in, the opening / closing door 28 of the carry-in port 26 is closed.

As described above, the raw pipe 1 is supported by the group of rollers 41 and conveyed in the heating furnace 21, and is heated to a high temperature during the conveyance. At that time, by placing a space L between the end faces of the raw pipe 1, it is possible to prevent the end faces from contacting (colliding) with each other due to the elongation of the raw pipe 1 during heating or the difference in the transport speed. If the distance L is too long, the efficiency becomes poor, so the distance L is controlled to 500 mm or less.

The above-mentioned heating is performed by the combustion heat of each burner 33, 35. At that time, the flame from the lower heating burner 33 flows from one lower part to the other lower part and then the other upper part. Will flow to the bottom heating burner 33 again
On the other hand, the flame from the upper heating burner 35 arranged at the positions facing each other in a staggered manner flows from the upper part of the other side to the upper part of the one side and then to the lower part of the one side. Therefore, the entire flame flows in a swirl shape when the heating furnace 21 is viewed from the vertical front side, and the swirl flow is smoothed by the circular inner surfaces of the upper furnace part 22A and the lower furnace part 22C without stirring the inside. To be done. As a result, the temperature difference in the furnace can be eliminated, and the temperature uniformity in the entire area of the furnace can be promoted, so that the raw tube 1 can be uniformly heated and the thermal efficiency can be further improved.

Further, since the lower heating burner 33 and the upper heating burner 35 are arranged at positions where the flame thereof does not directly hit the raw material pipe 1, uniform heating of the raw material pipe 1 can be promoted. In addition, the lower heating burner 33 and the upper heating burner 35
Is disposed at a position where the flame does not directly hit the roller 41, so that uniform heating of the raw pipe 1 can be further promoted.

[0031] By these, the original tube 1, which is carried into the heating furnace 21 at ambient temperature is gradually heated during transport in within the heating furnace 21, and 800 ℃ ~950 ℃ (A ₃ transformation point or higher) While maintaining a high temperature, the heating is performed at a uniform temperature in the circumferential direction and the length direction without bending. The raw pipe 1 heated to a predetermined temperature in this way is carried out from the heating furnace 21 through the carry-out port 27 by opening the opening / closing door 29, and then the welding seam position adjusting device.
You can bring it to 11. When the end of the raw tube 1 is completely unloaded, the opening / closing door 29 of the unloading port 27 is closed.

The hot smoke generated in the heating furnace 21 is discharged by the smoke exhaust device 50.
Can be discharged by. That is, the suction force acts on the smoke exhaust port 37 by the operation of the fan 54, whereby the smoke is sucked through the smoke exhaust port 37 to the first smoke pipe 52, and the main smoke passage 51 and the second smoke pipe.
After flowing to 53, it is discharged to the chimney 75 via the fan 54. Due to such suction and exhaust smoke, the inside of the heating furnace 21 has a negative pressure,
That is, when the pressure becomes lower than the atmospheric pressure, it is possible to prevent the raw pipe 1 from being bent. At that time, the degree lower than the atmospheric pressure can be controlled by adjusting the damper 56.

When hot smoke flows through the main flue 51, the heat is exchanged with the heat by the heat exchanger 58, and the air heated by this is supplied to the burners 33, 35 through the pipe group 59. . Therefore, the burners 33 and 35 perform efficient combustion by using the heated air as combustion air. Normally, the combustion air and fuel (gas, natural gas, gaseous fuel such as LPG, heavy oil,
Liquid fuel such as kerosene, solid fuel such as coal) is required,
The combustion efficiency is raised by these.

While the raw tube 1 is being heated in the heating furnace 21 as described above, the opening / closing door 2 of the carry-in port 26 and the carry-out port 27
When the valves 8 and 29 are opened, the flames from the heating burners 33 and 35 arranged in the vicinity of the valves 8 and 29 cause the inlet 26 side and the outlet 27.
However, the flames from the heating burners 33, 35 arranged near the smoke exhaust port 37 try to flow toward the smoke exhaust port 37 side, but at this time, they are located before and after the roller 41. These flows can be suppressed by the heat shield wall 38.

Therefore, it is possible to prevent the flames from the heating burners 33 and 35 from directly hitting the roller 41, and the roller 41 is prevented from becoming hot and damaged. Further, the heat outflow can be eliminated to improve the thermal efficiency, and the disturbance of the temperature in the furnace can be suppressed to uniformly heat the raw pipe 1 in the circumferential direction and the length direction.

In the above-mentioned embodiment, the heat shield wall 38 is arranged at two positions between the front and rear rollers 41 and the lower heating burner 33 is opposed between these heat shield walls 38. May be arranged between the rollers 41 in one or two steps, or in one place between the front and rear rollers 41.

In the above-mentioned embodiment, the heat shield wall 38 is
It is formed by stacking refractory bricks, but this may be made of materials other than refractory bricks, and the lower furnace part 22C.
It may be preformed integrally with the.

In the above-described embodiment, the circular original pipe 1 is shown as the hollow steel pipe, but it may be a square or rectangular hollow steel pipe. Further, in the above-mentioned embodiment, the heated raw pipe 1 is the large-diameter square steel pipe 3, but this may be the refined raw pipe 1A itself. In the above embodiment,
Although the lower heating burners 33 are arranged between all the adjacent rollers 41, they may be arranged one by one or two by two.

[0039]

According to the present invention having the above structure, the flame from the heating burner tries to flow to the opened inlet side or outlet side, and the flame from the heating burner is directed to the smoke outlet side. The tendency to flow can be suppressed by the heat shield walls located in front of and behind the roller. This can prevent the flame from the heating burner from directly hitting the roller, and prevent the roller from being damaged by high temperature. Further, heat can be prevented from flowing out, thermal efficiency can be improved, disturbance of the temperature in the furnace can be suppressed, and the hollow steel pipe can be uniformly heated in the circumferential direction and the length direction.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, and is a partially cutaway side view of a heating furnace in a heating facility for hollow steel pipes.

FIG. 2 is a vertical cross-sectional side view of a main part of a heating furnace in the heating equipment for hollow steel pipes.

FIG. 3 is a cross-sectional plan view of a main part of a heating furnace in the heating equipment for hollow steel pipes.

FIG. 4 is a vertical sectional front view of a heating furnace portion in the heating equipment for hollow steel pipes.

FIG. 5 is a vertical sectional front view of a heating furnace in the heating equipment for hollow steel pipes.

FIG. 6 is a plan view of smoke exhaust equipment in the heating equipment of the hollow steel pipe.

FIG. 7 is a perspective view of the steps of hot forming the hollow steel pipe.

[Explanation of symbols]

 1 Raw pipe (hollow steel pipe) 3 Large-diameter square steel pipe 11 Weld seam position adjusting device 14 Round steel pipe forming mill 17 Square steel pipe forming mill 20 Heating equipment 21 Heating furnace 22 Split furnace body 24 End furnace wall 25 End furnace wall 26 Carry-in port 27 Carry-out port 28 Open / close door 29 Open / close door 33 Lower heating burner 35 Upper heating burner 37 Smoke outlet 38 Heat shield wall 40 Roller conveyor 41 Roller 49 Rotation drive device 50 Smoke exhaust device 51 Main flue 60 Transport conveyor 61 Transport conveyor Predetermined pitch of P roller

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[Procedure amendment]

[Submission date] July 31, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

[0031] By these, the original tube 1, which is carried into the heating furnace 21 at ambient temperature is gradually heated during transport in within the heating furnace 21, and 723 ℃ ~950 ℃ (A ₃ transformation point or higher) While maintaining a high temperature, the heating is performed at a uniform temperature in the circumferential direction and the length direction without bending. The raw pipe 1 heated to a predetermined temperature in this way is carried out from the heating furnace 21 through the carry-out port 27 by opening the opening / closing door 29, and then the welding seam position adjusting device.
You can bring it to 11. When the end of the raw tube 1 is completely unloaded, the opening / closing door 29 of the unloading port 27 is closed.

Claims (1)

[Claims] 1. A hollow steel pipe which is conveyed in its length direction and is carried into a heating furnace, is heated to a high temperature by the combustion heat of a heating burner while being carried in the heating furnace, and is then carried out from the heating furnace. Of the heating furnace, the heating furnace is provided with a carry-in port, a carry-out port, and a smoke exhaust port, and opening and closing doors are provided at the carry-in port and the carry-out port, respectively, and a roller conveyor for transporting the hollow steel pipe is provided in the heating furnace. And a heat shield wall provided at a predetermined position between the rollers of the roller conveyor.