KR101018178B1 - Wire-rod Manufacturing Method - Google Patents

Abstract

A wire rod manufacturing method is provided that minimizes the occurrence of red scale.

The wire rod manufacturing method of the present invention, the raw material rolling step of rolling the heated material through rough rolling, finishing rolling (FM) and the final rolling (RSM) step; And a rolled material winding step of winding the rolled material; wherein, when the material cooling rate is 100% before the finishing rolling, before and after the final rolling, the final rolling step to minimize red scale generation Previously, the cooling rate of the material is characterized by consisting of 60 to 70%.

According to the present invention, the amount of material cooling water before the final rolling mill (RSM) before the wire rod water cooling is increased than before, and on the contrary, by controlling the inlet temperature of the final rolling mill of the material downward by minimizing the amount of material cooling water after the final rolling mill, The improved effect of minimizing the red scale of the coil product can be obtained.

Wire rod, red scale, final rolling, intensive cooling, final rolling inlet temperature control of material

Description

Wire Rod Manufacturing Method

The present invention relates to a wire rod manufacturing method, and more particularly, to increase the amount of material cooling water before the final rolling mill (RSM) prior to rolling wire water cooling, and to minimize the amount of material cooling water after the final rolling mill while minimizing the amount of material cooling water after the final rolling mill. The present invention relates to a wire rod manufacturing method which minimizes red scale generation of wire rod coil products.

Known wire rod production processes include roughing 160 × 160 mm billets, heated to a temperature of 900-1200 ° C, which can be rolled in a furnace, to rough, intermediate rough, intermediate finishing, finishing and final rolling (sizing Rolling), and a series of rolling processes.

This rolled material is finally made through a winding process to produce a wire rod having a diameter of about 5.5 to 50 mm.

In other words, the material passed through the heating furnace is hot rolled to a certain diameter through the series of rolling process described above, the rolled material is water-cooled through a water cooling stand to secure the target material, and the diameter of less than 14mm depending on the wire diameter Small diameter wire rods are wound and accumulated in the laying head, and large diameter wire rods having a diameter of 14 mm or more are wound in a reeler and finally produced as wire coil products.

By the way, in the conventional wire rod manufacturing process, the water-cooling form that determines the rolling temperature and material of the wire rod is filament rolling (FM, Finishing Mill)-> water cooling-> final rolling (RSM, Reducing & Sizing Mill) (sizing rolling)-> water cooling This was implemented.

By the way, in the case of conventional wire rod manufacturing, if the water cooling (concentration) is carried out in the step before the final rolling, it is possible to fear that the material size deviation occurs in the final rolling step. Subsequent cooling of the material was carried out in the subsequent water cooler.

For example, when the cooling rate of the raw material between finishing rolling after finishing rolling and after final rolling is 100%, the cooling rate of the raw material in the said stage before final rolling was less than 10%.

In addition, as can be seen in FIG. 1 to be described later, two water chillers are usually arranged after the final rolling mill to perform water cooling of the rolled material, and a size measuring device (T in FIG. 1) measuring the material size between the water chillers. In the actual process, intensive cooling of the material was performed in the water cooling stand disposed downstream of the size measuring device in consideration of the inflow of the cooling water into the material size measuring device T.

However, in the manufacture of such a conventional wire rod, thermal stress occurs in the material due to intensive water cooling after the final rolling mill and reduction of the use of the final rolling mill, resulting in severe red scale in the final wire rod coil. There was a problem that occurred (picture in Figure 3a).

Therefore, the red scale generated from the wire rods manufactured in the related art not only causes the quality of the wire rod product to deteriorate, but also causes various problems such as severe contamination of the pickling liquid during the wire pickling process at the customer, or a decrease in productivity. It became.

As a result, when the material is intensively cooled after the final rolling mill RSM as in the related art, the generation of thermal stress in the material, as well as the removal of the coolant concentrated in the pores of the surface of the material (see FIG. 4A), Since it was difficult, the cooling water remaining in this porous part was the main cause of red scale generation.

Therefore, the applicant of the present invention minimizes the cooling rate of the material after the final rolling step in the production of the wire rod, and the porosity generated in the material before the final rolling is peeled off the scale in the final rolling step to generate a red scale in the wire rod It has been proposed a method of manufacturing a wire rod of the present invention improved at least 50% or more.

The present invention has been proposed in order to solve the conventional problems as described above, an object of the present invention is to increase the amount of material cooling water before the final rolling mill (RSM) before the wire rod water cooling, and conversely, the amount of material cooling water after the final rolling mill is minimized. While controlling the entrance of the final rolling mill of the material downward, to provide a wire rod manufacturing method that minimizes the red scale generation of the wire rod coil products.

As one technical aspect for achieving the above object, the present invention, the raw material rolling step of rolling through the rough rolling, finishing rolling (FM) and the final rolling (RSM) step; And a rolled material winding step of winding the rolled material.
When the material cooling rate before the finishing rolling, before and after the final rolling is 100%, a wire rod manufacturing method comprising a cooling rate of the material to 60 ~ 70% before the final rolling step to minimize the red scale generation to provide.
Preferably, the temperature of the material entering the final rolling step is cooled to 830-900 ° C. to minimize red scale generation.
More preferably, when the material cooling rate before the finishing rolling, before and after the final rolling is 100%, the material is cooled at a material cooling rate of at least 10% before the finishing rolling.

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More preferably, the material is uniformly cooled at least on the finishing rolling side.

More preferably, at least one of the water coolers having an inner circular injector nozzle for uniformly cooling the material for uniform cooling of the material is disposed at the finishing rolling entrance, the final rolling entrance, and the exit side to realize uniform material cooling.

As described above, according to the method of manufacturing the wire rod of the present invention, the amount of material cooling water before the final rolling mill (RSM) before the wire coil water cooling is increased, and conversely, by controlling the entrance of the final rolling mill of the material downward while minimizing the amount of material cooling water after the final rolling mill. In addition, it is possible to reduce the red scale generation of the wire rod coil by at least 50%.

Therefore, the present invention eliminates the need for a reduction in product quality due to the red scale generated in the existing wire coil products, or additional work by the customer due to the red scale of the wire coil products.

As a result, the wire rod product of the present invention is to eliminate customer complaints.

Hereinafter, a preferred embodiment of the present invention according to the accompanying drawings.

First, looking at the wire manufacturing step according to the present invention in detail.

As shown in FIG. 1, after the billet is heated in a heating furnace, a rough rolling mill (not shown), an intermediate finishing mill (not shown), a finishing mill (FM) 10, and a final rolling mill 20 (RSM) are used. After passing through the hot rolling in order to produce a wire rod.

That is, the billet is charged into a heating furnace, heated to a temperature of 900 to 1200 ° C., then roughly rolled, and after roughly roughly rolled the raw material.

Next, as shown in FIG. 1, the raw material is cooled in the 1st water cooling stand (preliminary water cooling stand) 30 provided in the inlet side of the finishing mill 10, and is rolled by the finishing mill 10. FIG.

Then, the material is cooled at 830 to 900 ° C. in the first and second water cooling stages 40 and 50 at the inlet side of the final mill disposed between the finishing mill 10 and the final mill 20 to enter the final mill 20. The temperature of the material should be at least 900 ° C or less.

The reason why the temperature of the raw material at the inlet of the final mill 20 in the wire rod manufacturing step of the present invention is in the above range will be described in detail below.

Then, the raw material 2 which has passed through the final rolling mill 20 is cooled in the first and second water cooling stages 60 and 70 at the final mill exit side, and finally wound in the laying head 80, and the wound wire rod ( 2 ') is integrated into a wire coil 2 "in a reform tube 92 via a transfer table 90 which is air cooled.

For example, the wire rod manufacturing step of Figure 1 is a manufacturing step of the small diameter wire rod is wound in the laying head after the final rolling. (In the case of large diameter wire rod is integrated after winding while putting the raw material directly to the reeler in the medium-thin rolling.)

At this time, the finishing mill inlet-side water cooler 30, the final mill inlet-side first and second water cooler 40, 50, and the final mill outlet-side first, second water cooler 60, 70 is a stepwise material. The temperature is gradually lowered to prevent excessive temperature deviation of the material.

The water cooling units 30 to 70 are provided with a circular injector nozzle N inside the water cooling body B as shown in FIG. 2 to surround the material 2 to form the cooling water W. As shown in FIG. It can be provided in a form that makes it possible to perform uniform cooling of the rolled material (wire) 2 which is circular in cross section by spraying.

That is, the water coolers, in addition to the injector nozzle (N) for cooling the material by injecting the cooling water (W) in the material traveling direction, the stripper for spraying the cooling water (W) in the opposite direction of the material traveling direction to remove the material residual coolant It may be configured by including a water cooling stripper body (B ') having a nozzle (S).

Accordingly, the wire rod manufacturing step according to the present invention, the material rolling step of rolling the material (2) through rough rolling, finishing rolling (FM) and final rolling (RSM) step, and the rolled material winding the rolled material Consists of a winding step, it is characterized in that to form the temperature of the material at the inlet of the final mill entering the final mill 20 to 830 ~ 900 ℃, to minimize the red scale generation of the wire rod product.

For example, in the conventional wire rod manufacturing step, the final rolling inlet (for example, the finishing mill 10 and the final rolling mill) is not used in FIG. 1 without using the finishing mill 10 inlet water cooling stand 30 (preliminary water cooling stand). Although the first and second water cooling zones 40 and 50 are disposed on the (20) side, the cooling rate of the material is low.

Therefore, in the related art, the final sized rolled raw material 2 was cooled in the first and second water cooling zones 60 and 70 at the outlet side of the final rolling mill 20.

That is, conventionally, the temperature of the raw material 2 in the inlet which enters the last rolling mill 20 was about 960-1040 degreeC.

Therefore, since the temperature of the raw material entering the final rolling mill 20 of the present invention is higher than that of the present invention, the first and second water cooling stages 60 and 70 of the final rolling mill, in particular, the downstream side of the size measuring machine T. Intensive cooling in the second water chiller 70.

That is, the present invention concentrates the material in the finishing mill inlet-side first water cooler 30 and the final mill inlet-side first and second water cooler 40 and 50, which is not conventionally used. The characteristic is that temperature was adjusted to 830-900 degreeC.

This is because, after the final rolling mill 20, since the cooling rate of the material may be considerably lower than in the case of the present invention, the cooling rate of the material after the final rolling is lowered, and as shown in FIG. The cooling water residual ratio at is very low for the present invention.

4A and 4B are enlarged photographs of the surface of the conventional invention and the present invention. As shown in FIG. 4A, since the conventional cooling is concentrated after the final rolling, a large portion of pores that cause red scales are formed on the surface. It can be seen that the state, in the case of the present invention as shown in Figure 4b, because the concentrated material is cooled before the final rolling step, the final rolling step of peeling off the scale of the material, in the case of the present invention as shown in Figure 4b According to the equator, the cooling water remaining in the porous portion also decreases, indicating that little red scale is generated.

For example, as can be seen in the photo of Figure 3a, it can be seen that a large amount of red scale occurs in the wire rod coil manufactured in the prior art, in the case of the present invention as shown in Figure 3b it can be seen that almost no red scale occurs.

At this time, if the temperature of the raw material at the inlet of the final mill in the wire manufacturing step of the present invention is lower than 830 ℃, winding of the next wire is not normally made, if higher than 900 ℃, the material cooling width after the final rolling mill is substantially higher The same red scale occurrence problem occurs and there is a problem that the effectiveness is less.

Therefore, in the case of the present invention, the temperature of the raw material at the inlet of the final mill is controlled to be at least 900 ° C. or lower, so that concentrated cooling is avoided on the downstream side of the conventional final mill.

Meanwhile, in the manufacture of the wire rod of the present invention, the cooling rate of the material before and after finishing rolling (FM) and before final rolling (RSM), that is, the first water cooling stand 30 and the final rolling mill 20 at the inlet side of the finishing rolling mill 10. When the cooling rate of the material through the inlet and outlet side first and second water cooling zones 40, 50, 60 and 70 is 100%, it is preferable to cool the material before the final rolling (RSM) step. The material is cooled so that the rate is 60 to 70%.

The cooling rate of such a material may be a concept that interworks with the temperature range at the entrance of the final mill of the material.

On the other hand, in the prior art, there is no material cooling in the finishing mill inlet-side first water cooling zone 30, and in the final mill inlet-side first and second water cooling zones 40 and 50, the cooling rate of the material is 10% or less. In the rolling mill exit side 1st and 2nd water cooling zones 60 and 70, it concentrated-cooled so that the cooling rate of a raw material might be 90% or more.

In particular, the material was cooled to near 70% cooling rate in the second water cooling zone 70 downstream of the final mill exit side size gauge.

However, in the case of the present invention, the cooling rate of the material is configured to be 60 to 70% at least on the final mill inlet side so that the material temperature at the final mill inlet is maintained at 830 to 900 ° C.

That is, since the cooling rate of the raw material after the final rolling mill does not exceed the maximum of 40% unlike the conventional, it is to suppress the conventional problem, that is, red scale generation due to the concentrated cooling after the final rolling of the raw material.

On the other hand, in the present invention, the cooling rate of the material in the finishing mill inlet water cooler 30, which is not conventionally used, is at least 10%, preferably 10% or more. Since it is further controlled downward, it is desirable to prevent the quality problem caused by the sudden temperature drop of the material.

At this time, in the step before the final rolling, if the cooling rate of the material is less than 60%, the cooling rate of the material after the final rolling step is as high as conventional, the red scale is easily generated, in the step before the final rolling, the cooling of the material If the rate is higher than 70%, since the cooling rate is about 10% in the pre-finishing rolling step, and the material is rapidly cooled, it is difficult to substantially progress the normal process in the post-winding step.

Therefore, in the present invention, it is preferable to have the material cooling rate in the above range in the step before the final rolling.

And, of course, the cooling rate range of the raw material in the final pre-rolling stage is substantially related to the raw material temperature range at the inlet of the final rolling mill described above.

That is, the present invention is characterized in that in the step after the final rolling to determine the scale peeling and the final sizing of the material, the cooling width is lowered as much as possible to suppress the generation of the red scale as much as possible.

As described above, in the wire rod manufacturing step of the present invention, the material is uniformly cooled at least in the step before finishing the rolling, and the material is uniformly cooled at least 10%, that is, the material cooling rate of 10% or more.

At this time, if the cooling rate of the material in the pre-rolling step is lower than 10%, the cooling rate of the material in the step before the final rolling is sharply high will cause the problem described above.

Of course, the water cooling stages 30 to 70 of the finishing mill inlet side and the final mill inlet and outlet side of the present invention substantially spray the cooling water W while surrounding the material as described in FIG. 2. To achieve uniform cooling.

On the other hand, as shown in Figure 3a, the red scale is low in the winding temperature, especially in the case of the slow cooling material which is slowly cooled after the laying head 80, a lot occurs in low carbon carbon steel. For example, it is frequently generated in cold heading quality materials (SWRCH45F, SWRCH10A, etc.).

And, as shown in Figure 4a, there is a lot of porosity (porosity) in the scale layer of the conventional wire surface, the water molecules of the coolant flowed into the porous part is the transfer table 90 of FIG. When the material 2 'wound up is air-cooled, red scale is rapidly generated in contact with the air. Although not shown in the drawing, an air-cooling device that sucks air in the lower portion of the transfer table 90 is shown. There is a)]

As a result, if the amount of cooling water is concentrated after the final rolling step, the cooling water is concentrated and flows into the porous portion to increase the red scale.

Next, in Figure 5a when the wire rod manufacturing step of the prior art and the present invention, the red scale generation rate is shown as a graph.

For example, in FIG. 5A and FIG. 5B, as described above, in the case of SWRCH45F and SWRCH10A, which are cold-rolling materials, the red scale generation ratio is shown in a graph (in boxplot format) divided into the conventional and the present invention, respectively. The points in (box) are averages.

Therefore, in the case of FIGS. 5A and 5B, the red scale generation rate is reduced by 80% and 50%, respectively, in the case of the present invention.

Accordingly, according to the wire rod manufacturing method of the present invention, unlike the usual material water-cooled structure, by intensive cooling the material in the step before the final rolling, and in the step after the final rolling to implement a water cooling weak enough to meet only the winding temperature of the material, It can be seen that it is possible to suppress the generation of red scale that affects the quality of the wire rod products as much as possible.

While the invention has been shown and described in connection with specific embodiments so far, it will be appreciated that the invention can be varied and modified without departing from the spirit or scope of the invention as set forth in the claims below. It will be appreciated that those skilled in the art can easily know.

1 is a schematic diagram showing a wire rod manufacturing step according to the present invention.

2 is a block diagram showing the configuration of the water cooling stand of the present invention

Figure 3a and 3b is a photograph showing the state of the prior art and the present invention red scale wire rod

4A and 4B are enlarged photographs showing the surface of the wire rod according to the prior art and the present invention.

5A and 5B are graphs illustrating the conventional and the present invention red scale incidence rates divided into SWRCH45F and SWRCH10A, which are materials for cold pressing.

Explanation of symbols on the main parts of the drawings

10 .... Finishing mill 20 .... Final mill (sizing mill)

30 .... Water mill entering the finishing mill 40,50 .... Water mill entering the final mill

60,70 .... Final rolling mill exit water cooler 80 .... laying head

90 .... Winding material transfer table

Claims (5)

A raw material rolling step of rolling the heated material through rough rolling, finishing rolling (FM), and final rolling (RSM) step; And, A rolling material winding step of winding the rolled material; Including, When the material cooling rate before the finishing rolling, before and after the final rolling is 100%, the cooling rate of the material is configured to 60 to 70% before the final rolling step to minimize the red scale generation Wire rod manufacturing method. The method of claim 1, The method of manufacturing a wire rod, characterized in that to cool the temperature of the material entering the final rolling step to 830 ~ 900 ℃ to minimize the generation of red scale. The method of claim 1, When the material cooling rate before the finishing rolling, before and after the final rolling is 100%, the wire rod manufacturing method characterized in that for cooling the material at a material cooling rate of at least 10% before finishing rolling. The method according to any one of claims 1 to 3, A method for producing a wire rod, characterized in that the material is uniformly cooled at least at the end of the finishing rolling. The method of claim 4, wherein And at least one water cooler having an inner circular injector nozzle for uniformly cooling the material for uniform cooling of the material to be disposed at the finishing rolling entrance, the final rolling entrance and the exit.

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