JP6458662B2 - Billet manufacturing method and billet manufacturing equipment - Google Patents

Description

  The present invention relates to a billet manufacturing method and billet manufacturing equipment for manufacturing wire rods, steel bars and the like.

  Billets are used when performing wire rod rolling or bar rolling. As an example of a billet manufacturing method, first, a bloom obtained from a continuous casting machine is heated in a heating furnace. Subsequently, the heated bloom is rolled (hereinafter referred to as “bloom rolling”). Thereafter, the intermediate bloom which is a material to be rolled obtained by bloom rolling is further rolled (hereinafter referred to as “billet rolling”). Thereby, the billet which is an intermediate material of steel products is manufactured.

  As shown in Patent Document 1, generally, a hot scarf that removes surface defects such as scratches generated in an intermediate bloom is performed between a bloom rolling process and a billet rolling process. This removes surface defects in the intermediate bloom before billet rolling.

  As a technique related to the hot scarf, Patent Document 2 discloses an apparatus that removes the cutting chips adhering to the slab surface by injecting high-pressure water onto the slab at the downstream side of the hot scarf. Yes. Patent Document 3 discloses that a hot scarf is applied to four side surfaces of an oval billet in order to remove the decarburized layer on the billet surface layer.

JP-A-60-9502 JP 2006-68748 A JP-A-10-180309

  In the technique of Patent Document 1, there is a case in which the cutting-off blade generated when the hot scarf is carried out remains on the surface of the intermediate bloom after the hot scarf that is the material to be rolled. If billet rolling is performed in this state, a crack is generated on the billet surface, resulting in a reduction in product quality.

  Moreover, since the technique of patent document 2 is the scarf with respect to a slab, it is not disclosed at all about how it implements from the hot scarf process of a to-be-rolled material like an intermediate bloom to a billet rolling process. Moreover, although the method of the scarf of the 4 side surfaces of a billet is disclosed by patent document 3, it is not disclosed at all about the process to subsequent billet rolling.

  The present invention has been made in view of the above circumstances, suppresses the occurrence of nicks caused by the hot cutting residue remaining on the surface of the rolled material (for example, intermediate bloom) subjected to hot scarf, and It aims at carrying out subsequent billet rolling without a problem.

The present invention that solves the above problems is a billet manufacturing method for manufacturing a billet that is an intermediate material of a steel product, a hot scarf process for removing surface defects of the material to be rolled, and high-pressure water jetted onto the material to be rolled In this order, the cutting process includes a cutting cutting removal process for removing the cutting cutting stick adhering to the surface and a billet rolling process for rolling the material to be rolled, from the exit side of the hot scarf used in the hot scarf process, The distance to the entry side of the cutting blade removal device used in the cutting blade removal process is 3 m or more, and after the hot scarf process is completed, the cutting cutting blade removal process is started within 180 seconds, and the cutting blade removal is performed. In the process, high pressure water is jetted onto each surface of the material to be rolled to remove the cutting nose, and after completion of the nodding noble removal process, the billet rolling process is started after 30 seconds or more have elapsed. When To have.

  According to the present invention, by having a cutting-scraping removal step between the hot scarfing step and the billet rolling step, the cutting-slipping stick attached to the surface of the material to be rolled after the hot scarf is removed before the billet rolling. be able to.

Another aspect of the present invention is a billet manufacturing facility for manufacturing a billet that is an intermediate material of a steel product. In order, it is equipped with a cutting-blade removing device having a function of removing the blade and a billet rolling machine for rolling the material to be rolled , and the distance from the exit side of the hot scarf to the entry side of the cutting blade removal device is 3 m or more, and the above-mentioned cutting edge removing device is provided so as to start the cutting edge removal process within 180 seconds after the hot scarf on the material to be rolled. A plurality of the jet nozzles are provided so as to face each surface of the material to be rolled, and the billet rolling mill removes the cutting nodule of the material to be rolled by the above-mentioned cutting nose removing device. 30 seconds after It is characterized in that is provided so as to start the billet rolling process after the above elapsed.

  According to the present invention, it is possible to remove the cutting chips adhering to the surface of the material to be rolled before billet rolling. As a result, rolling can be performed in a state where no surface cutting is attached to the surface, and generation of nicks can be suppressed.

It is a figure which shows schematic structure of the billet manufacturing equipment which concerns on embodiment of this invention. It is a front view which shows schematic structure of the cutting-slipping device which concerns on embodiment of this invention. It is a figure which shows the effect of the hindrance suppression of the billet manufacturing equipment which concerns on this invention. It is a figure which shows the effect (according to the surface of a billet) of the whiskers suppression of the billet manufacturing equipment which concerns on this invention. It is a figure which shows the effect (according to the form of a flaw) of the whiskers suppression of the billet manufacturing equipment which concerns on this invention. It is a figure which shows the effect (according to the form of a flaw) of the whiskers suppression of the billet manufacturing equipment which concerns on this invention. It is a figure which shows the effect (according to the form of a flaw) of the whiskers suppression of the billet manufacturing equipment which concerns on this invention. It is a figure which shows the effect (according to the form of a flaw) of the whiskers suppression of the billet manufacturing equipment which concerns on this invention.

  Hereinafter, billet manufacturing equipment according to an embodiment of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the billet manufacturing facility 1 according to the present embodiment includes a heating furnace 10, a bloom rolling mill 20, a hot scurfer 30, a cutting-scraper removing device 40, and a billet rolling mill 50 from the upstream side of the conveyance line. The cooling floor 60 is arranged in order. The heating furnace 10, bloom mill 20, hot scurfer 30, billet rolling mill 50, and cooling bed 60 shown in FIG. 1 have the same structure as that of the conventional apparatus, and thus detailed description of the apparatus structure is omitted. To do.

  As shown in FIG. 2, the cutting edge removing device 40 according to the present embodiment includes a transport roller 41 that transports a square intermediate bloom B that is a material to be rolled after the hot scarf is performed. A pipe 42 through which water for removing the scale flows is provided around the intermediate bloom B to be conveyed. The pipe 42 is provided with four jet nozzles 43 that jet high-pressure water toward the intermediate bloom B. Each ejection nozzle 43 is attached so that one ejection nozzle 43 faces one surface with respect to each surface of the square intermediate bloom B having four surfaces (upper surface L, lower surface F, side surface S, side surface N). .

In addition, the cutting edge removing device 40 according to the present embodiment is configured such that the pressure of water ejected from the ejection nozzle 43 is, for example, 50 to 150 kgf / cm ² . By ejecting water at such a high water pressure, it is possible to remove not only the scale generated on the surface of the intermediate bloom B but also the cutting chips adhering to the intermediate bloom B after the hot scarf.

  It should be noted that the distance D from the exit side of the hot scurfer 30 to the entry side of the cutting chip removal device 40 is preferably secured to 3 m or more. Since the high-pressure water is used for the cutting-blade removing device, if the distance D is less than 3 m, even if a cover is provided, the high-pressure water is ejected from the gap between the cover and the intermediate bloom, and the ejected high-pressure water is hot. There is a possibility that the scarf 30 may be reached and adversely affect scarf cutting.

  The billet manufacturing facility 1 according to the present embodiment is configured as described above. Next, a billet manufacturing method using the billet manufacturing facility 1 will be described.

  As shown in FIG. 1, first, a 300 × 500 mm bloom obtained from a continuous casting machine (not shown) is heated to a predetermined temperature in a heating furnace 10 (heating step). Subsequently, the heated bloom is rolled into a 225-square intermediate bloom B by the bloom mill 20 (bloom rolling process). Thereafter, the intermediate bloom B, which is the material to be rolled, reaches the hot scarf 30 and hot scarf is carried out here (hot scarf process). Thereby, the surface defect produced in the intermediate bloom B is removed. However, at this time, a portion remains on the surface of the intermediate bloom B so as to stick the cutting edge.

  Subsequently, the intermediate bloom B reaches the welding chip removing device 40. Here, high-pressure water is ejected to the surface of the square intermediate bloom B. Thereby, the surface scale of the intermediate bloom B is removed (descaling step). Furthermore, in this embodiment, since the pressure of the water ejected from the ejection nozzle 43 of the cutting blade removal device 40 is high, the cutting blade remaining on the intermediate bloom surface after the hot scarf is also removed (the cutting blade removal). Process).

  At this time, it is desirable to remove the four surfaces of the intermediate bloom B. As a result, the remaining amount of the cutting nodule on the surface of the intermediate bloom can be surely reduced. As a result, it is possible to further suppress generation of nicks during billet rolling. Further, it is desirable to remove the cutting chips within 180 seconds after the hot scarf. This is because when 180 seconds have elapsed, the cutting edge is cooled and difficult to remove.

  Thereafter, the intermediate bloom B is rolled by the billet rolling mill 50 (billet rolling process). Thereby, a 122 square billet is manufactured. The intermediate bloom B that is rolled at this time is in a state in which the cutting chips adhering to the surface are removed. For this reason, even if billet rolling is carried out, nicks are unlikely to occur on the surface of the billet.

  The reason why high-pressure water is used for removing the cutting edge is that the processing speed is slow with a grinder or the like, and grinder grinding is difficult with a high-temperature steel material. However, the surface temperature of the intermediate bloom B is lowered when the cutting edge is removed using high-pressure water. For this reason, if billet rolling is attempted immediately after that, the load on the rolling mill becomes large, and rolling becomes difficult.

  In order to avoid this, it is necessary to start the billet rolling process after 30 seconds or more have elapsed after the end of the cutting cutting removal process. Thereby, billet rolling can be started after intermediate bloom B recuperates and surface temperature becomes high. If the surface temperature of the intermediate bloom B is approximately 900 ° C. or higher, there will be no hindrance to billet rolling.

  The billet rolled by the billet rolling machine 50 then reaches the cooling bed 60 and is cooled to a predetermined temperature. The billet manufacturing method according to the present embodiment is completed through the above steps.

  According to the billet manufacturing facility 1 according to the present embodiment, the billet manufacturing apparatus 1 having the function of removing the cutting nodule between the hot scurfer 30 and the billet rolling mill 50 is disposed, so that the billet Before carrying out the rolling, the cutting chips adhering to the intermediate bloom surface can be removed. Thereby, generation | occurrence | production of the nick which arises by billet rolling implemented after that can be suppressed.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, in the said embodiment, although it was set as a structure as shown in FIG. 1 regarding arrangement | positioning of the rolling mill etc. of the billet manufacturing equipment 1, a billet manufacturing equipment is not limited to the structure shown in FIG. In order to obtain the effect of suppressing the scratches according to the present invention, a cutting edge removing device 40 having a function of removing the cutting edge between the hot scurfer 30 and the billet rolling mill 50 is within the scope of the present invention. As long as it is arranged in the inside.

  Further, the billet size and shape are not limited to those described in the above embodiment.

  The billet manufactured using the conventional billet manufacturing facility and the number of nicks in the billet manufactured using the billet manufacturing facility according to the present invention were inspected.

  The conventional billet manufacturing facility is a facility that does not remove the cutting scrap between the hot skater and the billet rolling mill. In addition, the billet manufacturing facility according to the present invention has a function of removing the cutting nose on the four side surfaces of the billet between the hot scarf and the billet rolling mill that performs hot scarf on the four side surfaces of the billet. This equipment is equipped with a scraping machine. The billet manufacturing facility according to the present invention has a distance of 300 m from the hot scurfer to the cutting chip removal device and a distance from the cutting blade removal device to the billet rolling mill of 45 m. The billet transport time from the exit side of the hot scurfer to the entry side of the cutting scraper removal device is 150 seconds, and the billet transport time from the exit side of the cutting scraper removal device to the entrance side of the billet rolling mill is 40 seconds. Seconds.

  The inspection was conducted on a plurality of billets manufactured from molten steel produced on the same day. The billets to be inspected are as shown in Table 1 below. No. 1 and No. 2 are billets (BT) manufactured by conventional manufacturing equipment. On the other hand, No. 3 to No. 6 are billets (BT) manufactured by the manufacturing facility according to the present invention. In addition, about the billet of No. 3-No. 5, after the hot scarf complete | finished, the removal of the welding cutting was started within 180 seconds. On the other hand, with regard to the billet No. 6, the removal of the cutting chips was started after 210 seconds from the end of the hot scarf.

  The number of nicks generated on the billet surface was observed using a magnetic particle inspection method, and the number per billet of each No. was calculated. In the present embodiment, the number of counts is calculated by classifying the shape of the bruise into four types: “point hemegoz”, “round hemegiz”, “group hemegiz”, and “line mess”. did. Here, the “point mark” is a mark whose size is less than 2 mm. A “round hemkazu” is a nick of less than 5 mm. “Group Hegekizu” is a group of the above-mentioned “Point Hegekizu” and “Maruhegekizu”. A “line nick” is a linear dent.

  The evaluation results of the number of dents are shown in FIG. The vertical axis in FIG. 3 shows the ratio of the number of nicks per other billet based on the number of dents per No. 1 billet. In FIG. 3, the number ratio of No. 1 billet is set to 100, and the number ratio of other billets is shown. Note that the same expression method as that in FIG. 3 is used for the number ratio in the figures (FIGS. 4 to 8), which will be described later, showing the evaluation results of this example.

  As shown in FIG. 3, the number of nicks in the billet according to the present invention was smaller than the number of nicks in the conventional billet. That is, it can be seen that the production of billets can be suppressed more than ever by producing billets with the production facility according to the present invention. Moreover, generation | occurrence | production of the nick was able to be suppressed further about the billet of No.3-No.5 which started the removal of the cutting scraping within 180 seconds after completion | finish of a hot scarf.

  Next, the number of nicks by the surface of the billet was evaluated. The evaluation results are shown in FIG. As shown in FIG. 4, the billet according to the present invention tends to reduce the number of cracks in any aspect as compared with the conventional billet. In particular, the effect was remarkable on the lower surface (F surface) of the billet. Since the lower surface of the billet is in contact with the transport roller, it has been considered that the effect of suppressing the scratches according to the present invention cannot be expected. For this reason, the result shown in FIG. 4 overturned the original expectation.

  Next, it evaluated about the number for every form of a beige. 5 for the evaluation result of “Point Hegekizu”, FIG. 6 for the evaluation result of “Maruhegekizu”, and FIG. 7 for the evaluation result of “Group Hegekizu”. FIG. 8 shows the evaluation results of “”.

  As shown in FIGS. 5 to 8, it can be seen that the billet according to the present invention has a great effect of suppressing the generation of round nicks, group nicks, and line nicks. In particular, the effect of suppressing the group marks and the line marks is great. In addition, as described above, the number of group hems is counted as one in which the points and circles are gathered. For this reason, when each of the points and circles in a group of wounds is counted as one scratch, the points and circles of the billet according to the present invention shown in FIGS. The number ratio of dents is further reduced.

  As shown in the above embodiments, if the manufacturing facility according to the present invention is used, it is possible to significantly suppress the occurrence of nicks as compared with billets manufactured by a conventional manufacturing facility. In addition, after the hot scarf is finished, the removal effect of the cutting edge is started within 180 seconds, so that the effect of suppressing the cracking can be improved.

  The present invention can be applied to the manufacture of billets used as intermediate materials for steel products.

DESCRIPTION OF SYMBOLS 1 Billet manufacturing equipment 10 Heating furnace 20 Bloom rolling mill 30 Hot skar fur 40 Hot-melting fur removal apparatus 41 Conveyance roller 42 Piping 43 Injection nozzle 50 Billet rolling mill 60 Cooling bed B Intermediate bloom D Distance F Middle Bloom lower surface L Middle Bloom upper surface N Middle Bloom side S Middle Bloom side

Claims (2)

A billet manufacturing method for manufacturing a billet that is an intermediate material of a steel product,
A hot scarf process to remove surface defects of the material to be rolled;
A cutting-blade removal process for removing high-pressure water on the material to be rolled and removing the cutting-blade attached to the surface,
A billet rolling process for rolling the material to be rolled in order,
The distance from the exit side of the hot scarf used in the hot scarf process to the entry side of the cutting scraper removal apparatus used in the cutting scrap removal process is 3 m or more,
After the end of the hot scarf process, start the swarf removal process within 180 seconds,
In the above-mentioned welding cutting removal process, high pressure water is jetted onto each surface of the material to be rolled to remove the cutting cutting blade,
The billet manufacturing method of starting the billet rolling process after 30 seconds or more have elapsed after the end of the cutting and cutting process. A billet manufacturing facility for manufacturing billets that are intermediate materials of steel products,
A hot scarf to remove surface defects of the material to be rolled;
A cutting edge removing device having a function of removing the cutting edge adhered to the surface of the material to be rolled,
And a billet rolling machine for rolling the material to be rolled,
The distance from the exit side of the hot scurfer to the entry side of the welding scrap removal device is 3 m or more,
The above-mentioned cutting-slipping device is provided to start a cutting-slipping process within 180 seconds after the hot scarf on the material to be rolled,
The above-mentioned cutting-and-slipping device has an ejection nozzle that ejects high-pressure water,
A plurality of the ejection nozzles are provided to face each surface of the material to be rolled,
The billet rolling mill is a billet manufacturing facility provided so as to start a billet rolling process after 30 seconds or more have elapsed after removing the cutting scraps of the material to be rolled by the above-mentioned cutting scrap removal device.

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