JP4173142B2 - Cooling method for heated steel pipe - Google Patents

Description

  The present invention relates to various methods for cooling a heated steel pipe, such as a hot-formed heated steel pipe and an annealed (tempered) heated steel pipe.

Conventionally, as this type of cooling method, a heated steel pipe is water-cooled, gas-cooled (air-cooled), or gradually cooled (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 7-150247 (page 7)

  However, among the conventional cooling methods described above, in water cooling or gas cooling, water or gas (air) is usually cooled from the entire circumferential direction (up and down, left and right) to the heated steel pipe, In this case, the steel pipe is twisted or bent because forced cooling is performed at once by the cooling means. In the slow cooling, the cooling is usually performed at room temperature. In this case, the cooling time is long, so the efficiency is low, and a wide space is required for the slow cooling.

Therefore, according to the first aspect of the present invention, the heated steel pipe can be cooled efficiently and compactly without causing any twisting or bending, and particularly when the plate is thick and heated to a high temperature by hot forming. It is an object of the present invention to provide a method for cooling a heated steel pipe suitable for cooling a heated steel pipe.

In order to achieve the above-described object, the method for cooling a heated steel pipe according to claim 1 of the present invention is a method for cooling a heated steel pipe, and the cooling processing device includes a first cooling processing section and a second cooling processing section. In the first cooling processing unit, a cooling fluid that is a mixture of liquid and gas is sprayed from above on the heated steel pipe to cool it, and each of the first cooling processing unit includes a plurality of spray zones. And the hold zone are arranged at the intersection, and the heated steel pipe is alternately moved to the spray zone and the hold zone in order to cool in stages in the spray zone group, and in the hold zone group in the preceding spray zone. hold at chilled allowed temperature state, heating the steel pipe taken out of the hold zone in the final stage is transferred to the second cooling unit, a second cooling unit, cooling to a predetermined temperature by the first cooling unit Heating the steel pipe is obtained by said cooling immersed in liquid.

Therefore, according to the first aspect of the present invention, in the first cooling processing unit, the heating steel pipe can be cooled to a predetermined temperature by spraying a cooling fluid, which is a mixture of liquid and gas, onto the heating steel pipe from above. At that time, a slight temperature difference occurs in the circumferential direction and length direction during cooling in each stage, and the cooling temperature of the heated steel pipe cooled in a non-uniform (uneven) shape is uniform during the hold in each stage. It is possible to prevent the occurrence of distortion. Moreover, in a 2nd cooling process part, a heated steel pipe can be cooled from predetermined temperature to water temperature (normal temperature) by immersing and cooling the heated steel pipe cooled to predetermined temperature in the 1st cooling process part.

The method for cooling a heated steel pipe according to claim 2 of the present invention is characterized in that, in the configuration according to claim 1 , the first cooling treatment section cools the heated steel pipe to 250 ° C. or lower. .

Therefore, according to the second aspect of the present invention, the cooling by immersing the heated steel pipe in the liquid in the second cooling section is from 250 ° C. or lower to the water temperature (room temperature), so that most of the distortion, bending and deformation occur. It can be done without.

Furthermore, the method for cooling a heated steel pipe according to claim 3 of the present invention is characterized in that, in the configuration according to claim 1 or 2 , the liquid is water and the gas is air.

Therefore, according to the invention of claim 3 , cooling water and liquid can be provided at low cost.
Moreover, the method for cooling a heated steel pipe according to claim 4 of the present invention is characterized in that, in the configuration according to any one of claims 1 to 3 , the heated steel pipe is a hot-formed steel pipe. is there.

Therefore, according to invention of Claim 4 , a hot hot-formed steel pipe can be cooled suitably.

According to the first aspect of the present invention described above, in the first cooling processing unit, the cooling fluid, which is a mixture of liquid and gas, is sprayed onto the heated steel pipe from above, thereby cooling the heated steel pipe to a predetermined temperature. Can be performed without twisting or bending. At that time, a slight temperature difference occurs in the circumferential direction and length direction during cooling in each stage, and the cooling temperature of the heated steel pipe cooled in a non-uniform (uneven) shape is uniform during the hold in each stage. Therefore, it is possible to obtain a homogeneous heated steel pipe that is hardly twisted, bent, or deformed while being cooled to a predetermined temperature. Thereby, it is possible to provide a cooling method that is particularly suitable for cooling a heated steel pipe having a large plate thickness and heated to a high temperature by hot forming or the like. In the second cooling processing unit, the heated steel pipe cooled to the predetermined temperature in the first cooling processing unit is immersed in the liquid and cooled, so that the heating steel pipe is cooled from the predetermined temperature to the water temperature (normal temperature). , Twisting, bending, and deformation. In addition, the active cooling in the cooling processing apparatus enables efficient cooling as compared with slow cooling, and the cooling space can be made compact.

According to the second aspect of the present invention described above, the cooling by immersing the heated steel pipe in the liquid in the second cooling treatment section is cooling from 250 ° C. or lower to the water temperature (normal temperature), so that it is twisted, bent and deformed. Can be performed in a state in which almost no occurrence occurs.

Further, according to the third aspect of the present invention, cooling water and liquid can be provided at low cost.
Moreover, according to the fourth aspect of the present invention, a hot hot-formed steel pipe can be suitably cooled.

  As shown in FIGS. 2 and 4 (a), a long rough square steel pipe 1 is prepared. The rough rectangular steel pipe 1 is formed to have a predetermined thickness T and an outer surface radius of curvature LR that is larger than the outer surface radius of curvature R of the corner portion of the long steel pipe in the final product shape. The rough rectangular steel pipe 1 is cold-formed, and a butt weld 2 by butt welding is formed on one flat plate at that time. Further, the coarse rectangular steel pipe 1 is semi-molded as an outer dimension LE slightly longer than the outer dimension E in the final product shape.

As shown in FIGS. 2 and 3, the rough rectangular steel pipe 1 is transferred to the carry-in floor 11 and is conveyed. The coarse rectangular steel pipe 1 transported to the end portion of the carry-in floor 11 is transferred to a roller conveyor (an example of a transport means) 12 and transported on a transport path 12 a formed by the roller conveyor 12. During this conveyance path 12a, the crude rectangular steel pipe 1 and the heating means 15 for heating the entire A ₃ transformation point (e.g., 850-1,050 ° C.) than the dimensions of the coarsely braided RHS 1 heated normalized and shape And forming means 21 for hot forming.

  That is, the heating means 15 is a combustion heating method in which the coarse rectangular steel pipe 1 is put in a heating furnace 16, and at both ends in the front-rear direction of the heating furnace 16, a carry-in port and a carry-out port are formed by through holes, Open / close doors 17 are provided at the carry-in port and the carry-out port, respectively. A lower heating burner 18 is disposed at a lower portion on one side of the heating furnace 16 and at an intermediate position between the rollers of the roller conveyor 12, and is staggered on the other upper side of the heating furnace 16 and with respect to the lower heating burner 18. An upper heating burner 19 is disposed at a position opposite to the upper heating burner 19. An example of the heating means 15 is configured by the above 16-19 and the like.

As described above, the coarse rectangular steel pipe 1 conveyed to the terminal portion of the carry-in floor 11 is transferred to the roller conveyor 12 and is carried into the heating furnace 16 of the heating means 15 by the roller conveyor 12. The coarse rectangular steel pipe 1 is gradually and uniformly heated H from the outer surface side by the combustion heat of the burners 18 and 19 while being conveyed on the conveying path 12a in the heating furnace 16 (see a in FIG. 4). ). The heating H when the crude RHS 1 is performed so that the above A ₃ transformation point.

In this way, the coarsely braided square steel 1 heated to A ₃ transformation point or above the temperature, the opening and closing door 17 by causing the opening motion can be unloaded from the furnace 16 through the outlet port into the molding unit 21. When the end of the coarse rectangular steel pipe 1 is completely carried out, the opening / closing door 17 of the carry-out port is closed.

  As described above, the coarse rectangular steel pipe 1 heated by the heating means 15 is conveyed to the forming means 21 and hot formed into a normal size and shape by the forming means 21. That is, as shown in FIGS. 2, 3, and 4 (b), the forming means 21 is provided in four front and rear stages (single stage or plural stages). Each forming means 21 heats the rough square steel pipe 1 in a drawing shape through a pair of upper and lower and left and right forming rolls 23 that can be adjusted or exchanged with respect to the machine frame 22 side. It is made to form between.

  It should be noted that a necessary number of descaler devices 25 are provided around the forming means 21 at necessary places (before and after the forming means 21, only the front, only the back, between the stands, etc.). This descaler device 25 injects water with water pressure applied to the rough rectangular steel pipe 1 being formed, and the water scale can be removed to remove the mill scale and improve the surface skin.

  Therefore, the rough rectangular steel pipe 1 heated and carried into the forming means 21 is hot-formed into a drawing shape by the forming rolls 23 group. At this time, the hot forming is gradually (stepwise) performed by the plurality of forming means 21. ). By such hot forming, a hot-formed steel pipe (an example of a heated steel pipe) 3 having an outer dimension E between normal outer surfaces and a corner portion having a normal outer surface radius of curvature R can be obtained.

  The square hot-formed steel pipe 3 obtained in this way is transferred to the cooling processing device 30, where the cooling processing device 30 includes a first cooling processing unit 31 and a second cooling processing unit 37. That is, as shown in FIGS. 1 to 3, the first cooling processing unit 31 is provided with a cooling bed 32, and this cooling bed 32 is a conveyor type and supports a plurality of hot-formed steel pipes 3 in parallel. And it is made to convey in the horizontal direction with respect to the length direction on the cooling path 32a orthogonal to the conveyance path 12a.

  Three (a plurality of) spray zones 33A, 33B, and 33C and hold zones 34A, 34B, and 34C are formed (arranged) in the first cooling processing section 31 in an intersecting manner. At that time, the spray zones 33A, 33B, and 33C and the hold zones 34A, 34B, and 34C are set to the same zone length. The first-stage spray zone 33A is positioned at the start end of the cooling path 32a, and the last-stage hold zone 34C is positioned at the end of the cooling path 32a.

  Further, in each of the spray zones 33A, 33B, and 33C, a cooling fluid S that is a mixture of water (an example of liquid) and air (an example of gas) is disposed above the hot-formed steel pipe 3. The fluid spraying devices 35A, 35B, and 35C for spraying in a spray form are disposed. The spray zones 33A, 33B, and 33C are configured to cool the hot-formed steel pipe 3 stepwise by spraying the cooling fluid S in a spray form from the fluid spray devices 35A, 35B, and 35C.

  That is, the hot-formed steel pipe 3 heated to about 950 ° C., for example, is cooled to about 700 ° C. by spraying the cooling fluid S from the fluid spraying device 35A corresponding to the first stage spray zone 33A. The hot-formed steel pipe 3 at around 700 ° C. can be cooled to around 450 ° C. by spraying the cooling fluid S from the fluid spraying device 35B corresponding to the intermediate-stage spray zone 33B. The hot-formed steel pipe 3 at around 450 ° C. can be cooled to around 200 ° C. (less than 250 ° C.) by spraying the cooling fluid S from the fluid spraying device 35C corresponding to the zone 33C. .

  At the boundary between the spray zones 33A, 33B, 33C and the hold zones 34A, 34B, 34C, the spray-like cooling fluid S from the fluid spray devices 35A, 35B, 35C in the spray zones 33A, 33B, 33C is held. An air shutter or the like is provided to prevent scattering to the zones 34A, 34B, and 34C. An example of the first cooling processing unit 31 is configured by the above 32 to 35A, 35B, 35C and the like.

  The second cooling processing section 37 is provided with a conveyor-type transfer device 38, which receives the hot-formed steel pipe 3 sent from the end of the cooling bed 32, that is, the final hold zone 34C. And is transported in a direction transverse to the length direction. And the water tank (pool shape) 39 is formed in the part of the 2nd cooling process part 37, and the said conveying apparatus 38 is comprised so that the intermediate part may be located in the water tank 39. FIG.

  Cooling water (an example of a liquid) W is stored in the water tank 39 at a predetermined level, and the hot-formed steel pipe 3 having a temperature of about 200 ° C. sent from the last hold zone 34C is immersed in the cooling water W. Thus, the water temperature (room temperature) can be cooled. Here, the cooling water W in the water tank 39 is always drained while being supplied with water, and thus a constant water temperature (normal temperature) is maintained. An example of the second cooling processing unit 37 is configured by the above 38-39 and the like. An unloading device (conveyor) 41 for unloading the cooled product steel pipe 3a is disposed at the end portion of the conveying device 38.

  As described above, after hot forming, the square hot-formed steel pipe 3 conveyed to the end portion of the roller conveyor 12 is transferred to the cooling bed 32 of the first cooling processing unit 31, and in this cooling bed 32. While being conveyed on the cooling path 32a, it is cooled by the cooling fluid S in each of the spray zones 33A, 33B, 33C. At that time, the hot-formed steel pipe 3 is moved alternately to the blowing zones 33A, 33B, and 33C and the hold zones 34A, 34B, and 34C in order and cooled in stages by the blowing zones 33A, 33B, and 33C. At the same time, the hold zones 34A, 34B, 34C are configured to be able to hold in the temperature state cooled in the preceding blowing zones 33A, 33B, 33C.

  That is, for example, the hot-formed steel pipe 3 heated to around 950 ° C. is first sprayed with a cooling fluid S from the fluid spraying device 35A corresponding to the first spray zone 33A in a spray form from above. The whole is cooled so that the temperature falls to around 0 ° C. The hot-formed steel pipe 3 cooled to around 700 ° C. is moved to the first hold zone 34A and is held in an atmosphere around 700 ° C. Next, the hot-formed steel pipe 3 at around 700 ° C. is moved to the intermediate-stage spray zone 33B, and the cooling fluid S from the fluid spray device 35B is sprayed from above to form a whole so that the temperature is lowered to around 450 ° C. To be cooled. The hot-formed steel pipe 3 lowered to about 450 ° C. is moved to the intermediate stage hold zone 34B and held in an atmosphere of about 450 ° C. The hot-formed steel pipe 3 having a temperature of about 450 ° C. is moved to the final spray zone 33C, and the cooling fluid S from the fluid spray device 35C is sprayed from above so that the temperature is lowered to about 200 ° C. To be cooled. The hot-formed steel pipe 3 lowered to about 200 ° C. is moved to the final stage hold zone 34C and held in an atmosphere of about 200 ° C.

  Thus, in each hold zone 34A, 34B, 34C, by hold | maintaining in the temperature state lowered | hung by the blowing zone 33A, 33B, 33C of the front | former stage, in the circumferential direction and length direction of the hot-formed steel pipe 3 The heating temperature can be made uniform.

  That is, the hot-formed steel pipe 3 that has been cooled to around 700 ° C. in the first-stage spray zone 33A is held in an atmosphere at around 700 ° C. in the first-stage hold zone 34A, so that the first-stage spray zone 3A When cooling at 33A (around 700 ° C.), a slight temperature difference occurs in the circumferential direction and length direction, and the temperature of the hot-formed steel pipe 3 that is cooled in a non-uniform state (uneven shape) is made uniform during the hold. And the occurrence of distortion can be prevented.

  In addition, the hot-formed steel pipe 3 cooled to about 450 ° C. in the intermediate stage blowing zone 33B is held in an atmosphere at about 450 ° C. in the intermediate stage hold zone 34B, thereby cooling the intermediate stage blowing zone 33B. Some temperature difference occurs in the circumferential direction and length direction (around 450 ° C), and the temperature of the hot-formed steel pipe 3 cooled in a non-uniform (non-uniform) shape can be made uniform during the hold, Can be prevented.

  Further, the hot-formed steel pipe 3 cooled to about 200 ° C. in the final stage blowing zone 33C is held in an atmosphere of about 200 ° C. in the final stage hold zone 34C, thereby cooling the final stage blowing zone 33C. Some temperature difference occurs in the circumferential direction and length direction (around 200 ° C), and the temperature of the hot-formed steel pipe 3 cooled in a non-uniform state (uneven shape) can be made uniform during the hold, Can be prevented.

In addition, the movement between the zones of the hot-formed steel pipe 3 in the first cooling processing unit 31 is efficiently performed simultaneously (synchronously).
As described above, the hot-formed steel pipe 3 held at around 200 ° C. in the final hold zone 34C is taken out of the hold zone 34C and transferred to the second cooling processing unit 37. That is, the hot-formed steel pipe 3 taken out from the last-stage hold zone 34C is received by the transfer device 38. Then, the hot-formed steel pipe 3 at around 200 ° C. is immersed in the cooling water W of the water tank 39 and is cooled while being conveyed in the transverse direction with respect to the length direction by the conveying device 38. Can be cooled.

  The final product steel pipe 3a obtained by such cooling is taken out from the water tank 39 and then transferred to the carry-out device 41, where water droplets are removed by, for example, air blowing. The product steel pipe 3a that has reached the end of the carry-out device 41 is transported to a straightening device, a leading edge cutting device, a trailing edge cutting device, a cleaning device, and a rust prevention device (not shown), and after being processed as necessary. Is stored as a product. In addition, the product steel pipe 3a processed in this way is used as a steel pipe pillar of a steel structure, for example.

  Thus, in the 1st cooling process part 31, in the 1st cooling process part 31, the fluid S for cooling which is a mixture of a liquid and gas is sprayed on the hot-formed steel pipe 3 from the upper direction. The hot-formed steel pipe 3 can be cooled to a predetermined temperature without causing twisting or bending. Moreover, in the 2nd cooling process part 37, the hot-formed steel pipe 3 in the 2nd cooling process part 37 is cooled by immersing the hot-formed steel pipe 3 cooled to the predetermined temperature in the 1st cooling process part 31 in the cooling water W. Since the cooling is performed from a predetermined temperature to a water temperature (room temperature), it can be performed in a state in which almost no twisting, bending, or deformation occurs. In addition, the active cooling in the cooling processing apparatus enables efficient cooling as compared with slow cooling, and the cooling space becomes compact.

  In addition, a plurality of spray zones 33A, 33B, 33C and hold zones 34A, 34B, 34C are arranged in the first cooling processing unit 31 so that the hot-formed steel pipe 3 is sprayed with the spray zones 33A, 33B, 33C. By alternately moving to the hold zones 34A, 34B, and 34C and cooling in stages in the spray zones 33A, 33B, and 33C, and in the hold zones 34A, 34B, and 34C groups, the preceding spray zones 33A, 33B, By holding in the temperature state cooled at 33C, a slight temperature difference occurs in the circumferential direction and length direction during cooling in each stage, and the hot-formed steel pipe is cooled in a non-uniform (uneven) shape. The cooling temperature of 3 can be made uniform during the hold in each stage, and the occurrence of distortion can be prevented, so that the twist, bend and deformation are almost impossible. Homogeneous hot forming steel pipe 3 to Flip obtained in a state in which cooled to a predetermined temperature. Thereby, it becomes a cooling method suitable especially for cooling of the hot-formed steel pipe 3 with the thick plate | board thickness T and being heated to high temperature by hot forming.

  Then, by cooling the hot-formed steel pipe 3 to about 200 ° C. (250 ° C. or less) in the first cooling processing unit 31, cooling in the cooling water W in the second cooling processing unit 37 is about 200 ° C. Therefore, it can be performed in a state in which almost no twisting, bending or deformation occurs.

Further, by using water or cooling water W as the liquid and air as the gas, the cooling running water S or the cooling water W can be provided at low cost.
Moreover, when the heated steel pipe is the hot-formed steel pipe 3, the high-temperature hot-formed steel pipe 3 can be suitably cooled.
[Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG.

  The first cooling processing unit 31 is provided with only the fluid spraying device 35 over a certain length, and no hold zone is formed. For example, the rectangular heated steel pipe 5 heated to about 600 ° C. by annealing (tempering) is transferred to the cooling floor 32 of the first cooling processing unit 31, and the cooling floor 32 is placed on the cooling path 32 a. The cooling fluid S from the fluid spraying device 35 is sprayed from the upper side in a sprayed state, so that the whole is cooled to about 200 ° C. Then, the heated steel pipe 5 at around 200 ° C. taken out from the first cooling processing unit 31 is transferred to the second cooling processing unit 37, immersed in the cooling water W of the water tank 39 and gradually cooled, so that the water temperature (room temperature) is reached. To obtain the final product steel pipe 5a.

In such a second embodiment, since the first cooling processing unit 31 is not formed with a hold zone, the entire cooling unit 31 can be configured to be shorter and more compact. In particular, the first cooling processing unit 31 is thin and heated to a high temperature. It is suitable for cooling the heated steel pipe 5 and the heated steel pipe 5 heated to a low temperature such as annealing regardless of the plate thickness.
[Embodiment 3]
Next, Embodiment 3 of the present invention will be described with reference to FIG. 6 as a state adopted in a round steel pipe. That is, a long round steel pipe (an example of a heated steel pipe) 6 that has been hot-formed or annealed has a regular outer surface diameter D over its entire length, and butt-welded at one place in the circumferential direction. A weld 7 is formed.

  The round steel pipe 6 is hot-formed in the same manner as in the first embodiment, then cooled in the cooling processing device 30, and annealed in the same manner as in the second embodiment, and then the cooling processing device 30. In the cooling process.

  In the first embodiment described above, the three cooling zones 33A, 33B, and 33C and the hold zones 34A, 34B, and 34C are formed (arranged) in the first cooling processing unit 31 so that the hot-formed steel pipe 3 is formed. In this case, the spray zones 33A, 33B, and 33C and the hold zones 34A, 34B, and 34C are alternately moved sequentially to cool the spray zones 33A, 33B, and 33C in stages, and the hold zones 34A, 34B, and 34C groups. Although it is held in the temperature state cooled in the blowing zones 33A, 33B, and 33C in the previous stage, that is, the target temperature is lowered step by step as 200 ° C, the number of steps and the temperature drop Is optional, and the stepwise cooling temperature difference is also arbitrary.

  In the above-described first to third embodiments, in the first cooling processing unit 31, the hot-formed steel pipe 3, the heated steel pipe 5, and the round steel pipe 6 are cooled at around 200 ° C. (250 ° C. or lower) as a predetermined temperature. However, the predetermined temperature is arbitrarily set according to the material, thickness, heating temperature, etc. of the heated steel pipe.

In the first and second embodiments described above, a liquid other than water may be used as the liquid, and a gas or the like may be used as the gas.
In the above-described first embodiment, the hot-formed steel pipe 3 is used as a heated steel pipe, and in the second embodiment, the heated steel pipe 5 that is heated and heated by annealing is round as a heated steel pipe in the third embodiment. Each of the steel pipes 6 is shown, which is intended for various heated steel pipes.

  In the first and second embodiments described above, as the hot-formed steel pipe 3 and the heated steel pipe 5, for example, a one-seam square steel pipe by roll forming, a two-seam square steel pipe in which a pair of groove-shaped members by press forming are face-to-face welded, A two-seam square steel pipe formed by welding a pair of rolled grooves, a two-seam square steel pipe obtained by welding a pair of rolled chevrons facing each other, and the like are appropriately used.

  In the first and second embodiments described above, a square steel pipe having a regular tetragonal cross section is adopted as the hot-formed steel pipe 3 or the heated steel pipe 5, but this can also be adopted as a rectangular steel pipe having a rectangular cross section. It is. Furthermore, it can be similarly applied to various polygonal square steel pipes such as regular pentagons and regular hexagons.

  In the first and second embodiments, the hot-formed steel pipe 3 and the heated steel pipe 5 include a large-diameter and thick-walled square steel pipe, a large-diameter and thin-walled square steel pipe, a small-diameter and thick-walled square steel pipe, and a small-diameter It may be a thin square steel pipe. For example, a square steel pipe having an outer dimension E between regular outer surfaces of 300 to 700 mm and a sheet thickness T of 9 to 70 mm. In this case, the outer surface radius of curvature R of the corner portion is 1.0 to 3.0 times the sheet thickness. It is formed so as to be sharp.

  Steel, iron, etc. are employ | adopted as raw materials, such as the hot-formed steel pipe 3 in Embodiment 1 mentioned above, the heating steel pipe 5 in Embodiment 2, and the round steel pipe 6 in Embodiment 3. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of the present invention and is a schematic side view of a cooling processing device portion in a method for cooling a heated steel pipe. It is a partially cutaway perspective view of a hot forming facility including a cooling processing device portion in the method for cooling the heated steel pipe. It is a schematic plan view of the hot forming equipment including the cooling processing device part in the cooling method of the heating steel pipe. At the time of hot forming in the cooling method of the heating steel pipe, (a) is a front view of the heating means portion, (b) is a front view of the forming means portion. It is Embodiment 2 of this invention, and is a schematic side view of the cooling processing apparatus part in the cooling method of a heated steel pipe. It is Embodiment 3 of this invention, and is a front view of the round steel pipe in the cooling method of a heated steel pipe.

Explanation of symbols

1 Coarse square steel pipe 3 Hot-formed steel pipe (heated steel pipe)
3a Product steel pipe 5 Heated steel pipe 5a Product steel pipe 6 Round steel pipe (heated steel pipe)
11 Loading floor 12 Roller conveyor (conveying means)
DESCRIPTION OF SYMBOLS 15 Heating means 16 Heating furnace 21 Forming means 23 Forming roll 30 Cooling processing device 31 1st cooling processing part 32 Cooling floor 32a Cooling path 33A First stage blowing zone 33B Middle stage blowing zone 33C Last stage blowing zone 34A First stage Stage hold zone 34B Intermediate stage hold zone 34C Final stage hold zone 35 Fluid spraying device 35A Fluid spraying device 35B Fluid spraying device 35C Fluid spraying device 37 Second cooling processing unit 38 Transport device 39 Water tank S Cooling fluid W Cooling water (liquid)

Claims (4)

A method for cooling a heated steel pipe, wherein the cooling processing device includes a first cooling processing unit and a second cooling processing unit, and the first cooling processing unit supplies a cooling fluid that is a mixture of a liquid and a gas to the heating steel pipe. A plurality of spray zones and hold zones are arranged in the first cooling processing section, respectively, and the heated steel pipes are alternately and alternately arranged in the spray zones and the hold zones. It is moved and cooled step by step in the blowing zone group, and in the hold zone group, the heated steel pipe taken out from the last holding zone is held in the second cooling stage while being held in the temperature state cooled in the preceding blowing zone. The method for cooling a heated steel pipe, wherein the method is moved to the processing section, and the second cooling processing section cools the heated steel pipe cooled to a predetermined temperature in the first cooling processing section by immersing it in a liquid. The method for cooling a heated steel pipe according to claim 1, wherein the first cooling treatment section cools the heated steel pipe to 250 ° C or lower . The method for cooling a heated steel pipe according to claim 1 or 2 , wherein the liquid is water and the gas is air . The method for cooling a heated steel pipe according to any one of claims 1 to 3, wherein the heated steel pipe is a hot-formed steel pipe .

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