JPH09206825A - Manufacture of steel tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable shortening passing time of a tube stock at a carrying in- entry and a carrying out-exit in spite of being a hot forming system and to enable carrying during heat without any generation of scratch from carrying together with enabling being hard to be subjected to damage the tube stock carrying apparatus side within a heating furnace. SOLUTION: A hollow tube stock 1 is carried toward horizontal direction B in right angle to the length direction and thereby, open times of the carrying in-entry or the carrying out-exit are made shorten. The hollow tube stock 1 within the heating furnace 10 is carried at intervals of prescribed pitch from front end side to back end side and intermittently and progressively as a stationary state with a movable furnace body 22 doing not almost accept thermal influence by ascending and descending or moving before and behind with an intermittent and progressive transfer device 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a large-diameter rectangular steel pipe having a rectangular shape or a rectangular parallelepiped shape used for a column material for construction, a steel pipe used for manufacturing a round steel pipe, or the like. It is about the method.

[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. Molded into an approximate shape,
Next, while passing the approximate square steel pipe through multiple stages of forming rolls to form a square steel pipe, the groove abutting faces are sequentially tack welded, and the inner and outer surfaces of the groove are welded by automatic welding, then strain relief is performed. By doing so, a large-diameter square steel pipe is obtained.

However, in the square 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), so that the corner portion and the seam welded portion are The yield strength is increased, and the ductility is reduced. Since the mechanical properties are nonuniform and residual stress is generated, it is difficult to perform cutting work.

Therefore, recently, a round steel pipe having a predetermined diameter, plate thickness and length commensurate with a large-diameter square steel pipe is used as a raw pipe, and the raw pipe is conveyed in the length direction thereof to the front end of the heating furnace. In this heating furnace, the raw pipe is heated while being continuously conveyed in its lengthwise direction, the heated raw pipe is taken out from the rear end of the heating furnace, and then heated in a round steel pipe forming mill. It is provided that the refined raw pipe is hot-formed in a square steel pipe forming mill by hot forming into a refined raw pipe.

[0005]

However, in the above-mentioned manufacturing method for heating the raw pipe, the raw pipe is conveyed in the heating furnace at a low speed in the length direction thereof, and therefore the carry-in port at the front end thereof is provided. At the rear end, the passage time of the original pipe becomes longer, that is, the opening and closing time of the opening and closing door becomes longer, and it is arranged on the carry-in side and the carry-out side that are long open, and near the carry-in and carry-out ports. There is a problem that a flame flows from the installed heating burner and heat is discharged, which causes a decrease in thermal efficiency.

[0006] Further, the rollers and bearings of the roller conveyor device are directly hit by the flame from the heating burner and become high in temperature, which is liable to be damaged, and when a thick and large diameter raw pipe having a large unit weight is heated, There is a risk that a large load will be applied to each roller and the roller shaft will be deformed, and furthermore, the heated raw tube on the roller conveyor device may cause roller scratches due to linear contact with the rollers during transportation. There was such a problem.

Therefore, the invention of claim 1 of the present invention can shorten the passage time of the raw pipe at the carry-in port and the carry-out port, even though it is a hot forming system, and damages the raw pipe carrier device side in the heating furnace. It is an object of the present invention to provide a method for manufacturing a steel pipe which can be made difficult and can be heated and transported without causing transport scratches.

[0008]

In order to achieve the above-mentioned object, in the method for manufacturing a steel pipe according to claim 1 of the present invention, a hollow raw pipe is formed in a transverse direction perpendicular to its longitudinal direction. Transport it and put it in the front end of the heating furnace through the opening that can be opened and closed.
In this heating furnace, the hollow raw pipe is intermittently conveyed to the rear end side in a transverse direction perpendicular to its length direction by an intermittent sequential feeding device in which the movable furnace body moves up and down and moves back and forth. This is characterized in that after heating, the heated raw raw tube is taken out from the rear end of the heating furnace through an openable / closable carry-out port, and then hot-formed by a steel pipe forming machine to obtain a steel pipe.

Here, a large-diameter rectangular steel pipe is mainly manufactured, but a medium-diameter or small-diameter rectangular steel pipe or a round-shaped steel pipe can be manufactured in the same manner. Therefore, according to the invention of claim 1,
By conveying the hollow raw tube in the transverse direction perpendicular to its length and loading it into the front end of the heating furnace and unloading it from the rear end of the heating furnace, the opening time of the loading port and the loading port can be reduced. The length of the flame can be shortened, and the flow of flame from the heating burners disposed near these inlets and outlets toward both ports can be reduced.

By moving the movable furnace body downward and advancing it to the front end side, the loaded raw raw tube can be supported on the bottom furnace wall side. In this state, by operating the intermittent feeding device, the movable furnace body is first moved upward to lift the hollow raw tube supported on the bottom furnace wall side, and then the movable furnace body is moved backward to move the hollow raw tube. It is conveyed to the rear end side by a predetermined pitch, and the movable furnace body is moved down to pass the hollow raw tube to the bottom furnace wall side, and then the empty movable furnace body is moved forward and returned to the front end side by a predetermined pitch. .

As a result, the hollow raw pipe in the heating furnace is moved forward through the movable furnace body, which is hardly affected by heat, by the operation of the intermittent feeding device in the lateral direction perpendicular to the lengthwise direction. From the side to the rear end side, it is possible to carry out forward feeding intermittently at a predetermined pitch. At that time, the sequential feeding is basically performed with the hollow raw tube being in a stationary state, so that the heating feeding without causing the feeding scratch can be performed. In addition, even a large-diameter hollow raw pipe with a large load can always be stably conveyed without damaging the intermittent feeding device.

Then, the hollow raw tube discharged from the heating furnace is
A steel pipe having a predetermined size is obtained by carrying it into a steel pipe forming machine and performing hot forming.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. As shown in FIG. 7, when manufacturing a large-diameter rectangular steel pipe, for example, a round-shaped steel pipe 1 having a predetermined diameter, plate thickness and length commensurate with the large-diameter rectangular steel pipe is prepared as a hollow original pipe on the loading floor 5. It Here, the round steel pipe 1 is
Although it is manufactured in a state having a seam welded portion 2 by high frequency welding, arc welding, or the like, this may be a seamless round steel pipe 1.

The loading floor 5 is a conveyor type installed on the floor 6, supports a plurality of round steel pipes 1 in parallel, and extends in a transverse direction B perpendicular to the longitudinal direction A. And carry. The round steel pipe 1 conveyed to the terminal end of the loading floor 5 is carried into the heating furnace 10, and in the heating furnace 10, while being conveyed in the lateral direction B perpendicular to the length direction A, A
It is heated to H above ₃ transformation points.

As shown in FIGS. 1, 2 and 6, the heating furnace 10 has a bottom furnace wall whose upper surface forms a support surface 11a.
11, side furnace walls 12 standing from both left and right ends of the bottom furnace wall 11, and front furnace walls standing from the front end of the bottom furnace wall 11.
13 and the rear furnace wall 14 that is erected from the rear end of the bottom furnace wall 11
And a ceiling furnace wall 15 provided between the upper ends of the side furnace wall 12, the front furnace wall 13, and the rear furnace wall 14, etc., to form a box shape. The heating furnace 10 is supported on the floor 6 side via a support frame 7 and the like.

The front furnace wall 13 has a carry-in port 16 and the rear furnace wall 13
A carry-out port 17 is formed at 14, and these carry-in port 16 and carry-out port 17 are provided.
Opening / closing doors 18 and 19 are provided in each. Here, the carry-in port 16 and the carry-out port 17 are the minimum dimensions that allow the round steel pipe 1 having the maximum diameter and length to be heated to pass in the transverse direction B perpendicular to the length direction A thereof. And is formed in a shape. A predetermined number of heating burners 20 are arranged at predetermined positions such as the furnace walls 12 to 15. Also, the ceiling furnace wall 15
In the part adjacent to the carry-out port 17 of
21 are formed.

On the side of the bottom furnace wall 11 is provided a movable furnace body 22 that moves up and down and moves back and forth. That is, slits 23 having a width in the left-right direction are formed at a plurality of positions in the left-right direction of the bottom furnace wall 11 (four positions in the embodiment) over substantially the entire length in the front-rear direction, and each of these slits 23 has a movable furnace body. 22 is fitted so that it can be moved up and down and moved back and forth. Further, on the upper surface of the movable furnace body 22, recessed arc-shaped lifting surfaces 22a are formed at a pitch corresponding to a predetermined pitch described later.

On the side of the support surface 11a supported by the bottom furnace wall 11,
Rotating protrusions 24 are provided at a predetermined number or positions. The rotating projection 24 receives the round steel pipe 1 that has moved downward (described later) before the support surface 11a, and automatically rotates (rotates) the round steel pipe 1 in a semi-rotating state. The heating furnace 10 has an inclined surface in which the front end side is the upper side and the rear end side is the lower side. The heating furnace 10 is configured by the above 11 to 24 and the like.

A carry-in means 25 is arranged outside the carry-in entrance 16, and a carry-out means 26 is arranged outside the carry-out exit 17. The carry-in means 25 and the carry-out means 26 are of a clamp type, a lift type, or the like, and may be omitted by utilizing the conveyor conveying force of the carry-in floor 5.

The round steel pipe 1 carried into the heating furnace 10 is
By the intermittent sequential feeding device 30 for moving the movable furnace body 22 up and down and moving back and forth, the transverse direction B perpendicular to the length direction A thereof is obtained.
At this time, high temperature heating H is performed while being intermittently conveyed to the rear end side. That is, a recess 8 is formed on the floor 6 side below the bottom furnace wall 11, and a base frame 31 is arranged at the bottom of the recess 8. A plurality of support rods 32 are erected from the base frame 31,
The bottom side of the bottom furnace wall 11 is supported by the upper ends of these support rods 32.

A movable body 33 that moves up and down and moves back and forth is arranged so as to avoid the group of support rods 32. The movable body 33 includes a lower frame 34 and a plurality of left and right lower frames 34 in the left-right direction. A support rod 35 is provided upright from a plurality of front and rear portions at a location (four locations in the embodiment), a support plate 36 provided between the upper ends of the front and rear support rods 35 at each location, and the like.
The movable furnace body 22 is fixed to the upper surface of 36.

The raising / lowering device 37 for raising and lowering the movable body 33 is composed of a plurality of levers provided at a plurality of positions in the front-rear direction so as to be swingable in the front-rear direction via lateral pins 38 on the base frame 31 side. 39, a push-pull rod 40 in the front-rear direction connected between the lower ends of these levers 39, and the push-pull rod 40.
Lifting cylinder 41 connected to one end of each and each lever
The roller 42 is pivotally attached to the upper end of 39 and is in contact with the lower surface of the lower frame 34 of the movable body 33. A pair of left and right lifting devices 37 are arranged as a pair, and at that time, both lifting cylinders 41 are operated in synchronization.

A forward / backward movement cylinder 43 for moving the movable body 33 back and forth is provided between the base frame 31 and the arm body 44 which is continuously connected forward from the lower frame body 34. The forward / backward movement cylinder 43 and the lifting / lowering movement cylinder 41 are connected to a corresponding connecting member so as to be swingable relative to each other. The intermittent feeding device 30 is configured by the above 31 to 44. It should be noted that the gap formed while changing to the portion of the slit 23 by the operation of the movable furnace body 22 is appropriately closed by a sealing device (not shown) or the like.

As described above, the round steel pipe 1 transported to the end of the loading floor 5 has the loading means 25 after the opening / closing door 18 is opened.
Is carried in the transverse direction B perpendicular to the lengthwise direction A, and is carried into the heating furnace 10 through the carry-in port 16. At this time, the movable furnace body 22 is moved down and moved forward toward the carry-in port 16 side. Therefore, the loaded round steel pipe 1
2 is supported by the support surface 11a of the bottom furnace wall 11 as shown in FIG. 2, and the opening / closing door 18 is closed after loading.

In this state, the group of levers 39 is swung by the contraction of the lifting / lowering cylinder 41, and the rollers 42 are moved upward.
By raising the movable body 33 through the group, this movable body 33
Moving the movable furnace body 22 group in the slit 23 through the
Then, as shown in FIG. 3, the round steel pipe 1 supported by the support surface 11a can be lifted via the lifting surface 22a. Then, due to the extension of the cylinder 43 for forward and backward movement,
By moving the movable body 33 supported by the 42 group backward, the movable furnace body 22 group is moved backward E in the slit 23 through the movable body 33, and as shown in FIG. twenty two
The round steel pipe 1 lifted and supported via a is conveyed to the rear end side by a predetermined pitch.

Then, the lever 39 group is swung by the extension of the ascending / descending cylinder 41, and the movable body 33 is lowered via the roller 42 group which is swung downward, whereby the movable furnace body 22 is moved through this movable body 33. The group is moved down F in the slit 23,
Thus, as shown in FIG. 5, the round steel pipe 1 supported by the lifting surface 22a can be passed to the support surface 11a. Thereafter, the movable body 33 supported by the group of rollers 42 is moved forward by contraction of the front-rear movement cylinder 43, and the movable furnace body 22 group is moved forward G in the slit 23 via the movable body 33, Thus, as shown in FIG. 2, the empty lifting surface 22a can be returned to the front end side by a predetermined pitch.

As a result, the round steel pipe 1 can be carried into the heating furnace 10 through the carry-in port 16 which is opened for a short time. Then, in the heating furnace 10, the round steel pipe 1 is moved in the lateral direction B perpendicular to the length direction A by the operation of the intermittent feeding device 30 through the movable furnace body 22 which is hardly affected by heat. , From the front end side to the rear end side, it is possible to carry out forward feeding intermittently at a predetermined pitch. Then, during the transportation in the heating furnace 10, the flame from the heating burner 20 can heat at a high temperature H above the A ₃ transformation point.

At this time, in the heating furnace 10, a plurality of round steel pipes 1 can be sequentially fed and conveyed. The progressive transport is basically performed while the round steel pipe 1 is in a stationary state, so that the heating transport can be performed without causing transport scratches. Further, at a predetermined position, the round steel pipe 1 that is moved down F is brought into contact with the inclined surface of the rotating projection 24, and is automatically rotated in a semi-rolled state by rolling on the inclined surface and then supported. surface
It will be accepted by 11a. As a result, the round steel pipe 1 is rotated a single time or a plurality of times during heating to change the surface to be supported, so that the heating can be homogenized.

The round steel pipe 1 thus heated and conveyed to the vicinity of the carry-out port 17 passes through the carry-out port 17 which is opened for a short period of time at the time of the above-described downward movement F at the timing of the descending motion F described above. By the operation, it is carried out in the lateral direction B perpendicular to the length direction A, and then taken out from the heating furnace 10 onto the conveyor 45. Then, the open / close door 19 is closed after being carried out.

As described above, the round steel pipe 1 which has been heated to a predetermined temperature in the heating furnace 10 and carried out has the shape shown in FIGS.
As shown in, the welding seam position adjusting device 46 is passed.
The welding seam position adjusting device 46 is composed of a support roll 47, a press roll 48, etc., and the round steel pipe 1 is rotated around the pipe axis via the rolls 47, 48 to position the seam weld portion 2. Are aligned in a certain direction. This fixed direction is a position where the seam welded portion 2 is always present near the center of the flat plate portion when the large-diameter square steel pipe that is the final product is obtained. When the seamless round steel pipe 1 is conveyed, the portion of the welding seam position adjusting device 46 is passed, and when only the seamless round steel pipe 1 is used,
The process by the welding seam position adjusting device 46 is deleted.

The round steel pipe 1 from the welding seam position adjusting device 46 is carried into the round steel pipe forming machine 50. Here, the round steel pipe 1 is hot-formed into a draw shape through a plurality of sizing rolls 51 and the like, and the round steel pipe 1 is made to have a predetermined diameter so that a square steel pipe as a final product is finished with a predetermined size. The refined round steel pipe 1A is obtained by refining. Round steel pipe forming machine
Necessary locations around 50 (before and after round steel pipe forming machine 50,
The necessary number of descaler devices 53 are provided only in the front, only in the back, and between the stands. The descaler device 53 is for injecting water under hydraulic pressure onto the refined round steel pipe 1A, and can remove mill scale and the like to improve the surface texture.

The refined round steel pipe 1A refined by the group 53 of round steel pipe forming machines in this way is the former-stage square steel pipe forming machine 55.
Be delivered to. Here, hot forming (forming temperature A ₃ transformation point or higher) is performed through a plurality of zigzag rolls 56, and at that time, each flat plate portion of the polygonal hollow steel pipe 3 immediately after hot forming is continuous. It is formed into an outward arc surface along the face.

Next, the polygonal hollow steel pipe 3 is carried into a post-stage square steel pipe forming machine (steel pipe forming machine) 57. In this post-stage rectangular steel pipe forming machine 57, hot forming (forming temperature, A ₃ transformation point or higher) is performed through a plurality of flat rolls 57, and the latter stage (final stage) of the polygonal hollow steel pipe 3 is reduced. Molding takes place,
As a result, a large-diameter rectangular steel pipe (steel pipe) 4 having a predetermined size and serving as a final product is hot-formed.

The hot-formed rectangular steel tube 4 is received by the cooling floor 60. The cooling floor 60 is of a conveyor type and supports a plurality of square steel pipes 4 in parallel and conveys them in a direction transverse to the length direction. This cooling floor 60
During the transportation in, the square steel pipe 4 is radiated by the air cooling method I, that is, gradually cooled. By this slow cooling, each flat plate portion of the square steel pipe 4 is contracted so that the arc surface becomes a straight surface, and the corner portion has a rounded shape.
Becomes sharper and the section modulus becomes higher. The rectangular steel pipe 4 reaching the end of the cooling floor 60 is conveyed to a straightening device, a tip cutting device, a rear end cutting device, a cleaning device, and a rust preventive device (not shown), processed by each of them, and then stored as a product. To be done.

In the above embodiment, the heated round steel pipe 1 is the square steel pipe 4, but the refined round steel pipe 1A itself may be a product. Next, another embodiment of the present invention will be described with reference to FIG.

That is, for example, when manufacturing a large-diameter square steel pipe, a square steel pipe (or rectangular steel pipe) 3A having a predetermined diameter, plate thickness, and length commensurate with this square steel pipe is placed on the loading floor 5 as a hollow original pipe. Be prepared. And loading floor 5
The square steel pipe 3A conveyed to the end portion of is conveyed into the heating furnace 10, and in this heating furnace 10, while being conveyed in the transverse direction B perpendicular to the length direction A, the A ₃ transformation point The high temperature heating H is performed as described above.

At this time, the upper surface of the movable furnace body 22 is formed as a flat lifting surface 22b. Further, the square steel pipe 3A carried out from the heating furnace 10 is not passed through the round steel pipe forming machine 50, but is passed through the conveyor 45 from the pre-stage square steel pipe forming machine 55 to the post-stage square steel pipe forming machine 57 to generate heat. Molded between.

In the above embodiment, the refined round hollow steel pipe 1
The hot forming from A to the square steel pipe 4 or the hot forming from the square steel pipe 3A to the square steel pipe 4 is performed by the front-stage square steel pipe forming machine 55 and the rear-stage square steel pipe forming machine 57 in two stages, front and rear. However, this may be hot-formed by only one, or may be hot-formed by two or more stages.

In the above-mentioned embodiment, the large-diameter square steel pipe 4 is manufactured, but the medium-diameter or small-diameter square steel pipe 4 can be manufactured in the same manner. Further, in the above-described embodiment, the square steel pipe 4 having a square cross section is manufactured, but the square steel pipe 4 having a rectangular cross section can be manufactured similarly. Furthermore, by changing the roller arrangement of the double-sided steel pipe forming machines 55, 57, it is possible to perform hot forming of polygonal steel pipes such as pentagonal steel pipes and hexagonal steel pipes.

[0040]

According to claim 1 of the present invention described above, the opening time of the carry-in port and the carry-out port can be shortened when the hollow raw pipe is carried into the front end of the heating furnace or carried out from the rear end. The flow of flames from the heating burner to the carry-in and carry-out ports can be reduced,
Thermal efficiency can be improved. In addition, by moving the movable furnace body up and down or moving back and forth by the intermittent sequential feeding device, the hollow raw pipe in the heating furnace is moved to a predetermined pitch from the front end side to the rear end side through the movable furnace body that is hardly affected by heat. It is possible to carry out sequential feeding intermittently. At that time, the progressive feeding can be performed basically with the hollow raw tube in a stationary state without causing transport scratches, and even with a large load and thick raw large diameter hollow raw tube,
The intermittent feeding device can always be carried stably without damaging it.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a vertical cross-sectional side view of a heating furnace portion in a method for manufacturing a steel pipe.

FIG. 2 is a vertical sectional side view of a carry-in port portion of a heating furnace in the method for manufacturing the steel pipe.

FIG. 3 is an explanatory view when the steel pipe is moved upward in the manufacturing method of the steel pipe.

FIG. 4 is an explanatory diagram when the steel pipe is moved backward in the manufacturing method of the same.

FIG. 5 is an explanatory view when the steel pipe is moved downward in the method for manufacturing the steel pipe.

FIG. 6 is a vertical sectional front view of a heating furnace portion in the method for manufacturing the steel pipe.

FIG. 7 is a process perspective view in the method for manufacturing the steel pipe.

FIG. 8 is a process explanatory view in the method for manufacturing the steel pipe.

FIG. 9 shows another embodiment of the present invention and is a vertical cross-sectional side view of a carry-in port of a heating furnace in a method for manufacturing a steel pipe.

[Explanation of symbols]

 1 Round steel pipe (hollow raw pipe) 1A Refined round steel pipe 3 Polygonal hollow steel pipe 3A Square steel pipe (hollow raw pipe) 4 Square steel pipe (steel pipe) 5 Carrying bed 6 Bed 10 Heating furnace 11 Bottom furnace wall 11a Support surface 16 Carrying port 17 Carrying port 18 Opening / closing door 19 Opening / closing door 20 Heating burner 22 Movable furnace body 22a Recessed arcuate lifting surface 22b Flat lifting surface 24 Rotating projection 25 Loading means 26 Unloading means 30 Intermittent sequential feeding device 33 Moving body 37 Lifting Actuator 43 Front-rear cylinder 57 Rear-stage rectangular steel pipe forming machine (steel pipe forming machine) 60 Cooling floor A Length direction B Lateral direction D Upward movement E Backward movement F Downward movement G Forward movement H High temperature heating I Heat dissipation

Claims (1)

[Claims] 1. A hollow raw tube is conveyed in a transverse direction at a right angle to its lengthwise direction and is inserted into a front end of a heating furnace through an openable / closable inlet, and the hollow raw tube is placed in the heating furnace. , The movable furnace body is moved up and down and moved back and forth by an intermittent feeding device to heat it while intermittently conveying it to the rear end side in a lateral direction at a right angle to its length direction. A method for producing a steel pipe, comprising: taking out from a rear end of a heating furnace through an openable / closable carry-out port and then hot forming the steel pipe by a steel pipe forming machine.