JP4370996B2 - Descaling method and descaling equipment in hot rolling - Google Patents

Description

  The present invention relates to a descaling method and descaling equipment for removing scale generated on the surface of a material to be rolled by jetting high-pressure water in a hot rolling line for hot rolling steel or the like.

  In the hot rolling line, oxidized scale is generated on the surface of the hot rolled material, and if it is caught in the rolling mill as it is, wrinkles enter the surface of the roll and the rolled material, reducing the quality. It is necessary to remove this scale before it is bitten, and usually the surface of the material to be rolled by injecting high pressure water from the injection nozzle onto the surface of the material to be rolled from the downstream side to the upstream side of the conveying line of the material to be rolled. Descaling equipment is provided to remove the scale generated in the system.

  At that time, the spray water scatters after colliding with the surface of the material to be rolled and flows to the upstream side of the conveying line, and the scattered water lowers the temperature of the material to be rolled, causes equipment erosion, When a plurality of rows of spray nozzles are used in the transport line direction, there is a problem in that the scattered water from the downstream spray nozzle interferes with the spray water from the upstream spray nozzle and reduces the descaling efficiency. . Therefore, conventionally, a plate-shaped scraper (draining plate) for scooping up and collecting the scattered water after colliding with the surface of the material to be rolled is installed upstream of the spray nozzle, and the lower end of the scraper is placed on the surface of the material to be rolled. Although the scattered water is collected by contacting the scraper, the scraper has a considerable weight in order to counter the high-pressure jet water, and there is a risk of wrinkling the material to be rolled by the lower end of the scraper.

  Therefore, in order to prevent wrinkling of the material to be rolled, a scraper is arranged on the upstream side of the injection nozzle with a slight clearance from the surface of the material to be rolled, and the surface of the material to be rolled is further upstream of this scraper. There has been proposed a descaling facility in which a draining roll that blocks the flow of scattered water passing through the gap of the scraper is disposed (see, for example, Patent Document 1).

Similarly, a first-stage scraper is disposed on the upstream side of the injection nozzle with a slight clearance from the surface of the material to be rolled, and in contact with the surface of the material to be rolled on the further upstream side of the scraper, the clearance of the scraper is arranged. There has been proposed a descaling facility in which a lightweight second-stage scraper that collects scattered water that has passed through is disposed (see, for example, Patent Document 2).
Japanese Utility Model Publication No. 61-107409 Japanese Utility Model Publication No. 05-044304

  However, in the descaling equipment shown in Patent Document 1 and Patent Document 2, it is necessary to dispose a draining roll or a second-stage scraper further upstream of the scraper disposed upstream of the injection nozzle. The equipment configuration becomes complicated. Also, the installation space for the descaling equipment is usually limited in relation to other equipment, and it is difficult to arrange the draining roll or the second-stage scraper in the limited space. Furthermore, when a plurality of rows of spray nozzles are used in the direction of the transport line, since the scattered water is not sufficiently collected by the first-stage scraper, the descaling efficiency due to the spray water from the upstream spray nozzle is low. There is a problem of lowering.

  The present invention has been made in view of the above circumstances, and in the descaling equipment that removes the scale generated on the surface of the material to be rolled by jetting high-pressure water, the scattered water after colliding with the surface of the material to be rolled is removed. An object of the present invention is to provide a descaling method and descaling equipment in hot rolling that can be accurately recovered with a simple equipment configuration without wrinkling the material to be rolled.

  As a result of intensive studies to solve the above problems, the inventors have determined a predetermined injection angle by a predetermined injection pressure from the injection nozzle toward the upstream side of the material to be rolled to obtain an appropriate descaling effect. The high-pressure water sprayed on the surface of the material to be rolled in does not flow on the surface of the material to be rolled toward the upstream side of the conveyance line after colliding with the surface of the material to be rolled, but at a certain height above the surface. I found that it was mostly scattered. Specifically, it has been found that most high-pressure water scatters in the angular direction of 0.8 ° or more upward from the horizontal direction toward the upstream side of the material to be rolled. And if the scraper is installed so that most of the scattered water that scatters away from the surface of the material to be rolled can be collected in this way, it is possible to accurately collect the scattered water without bringing the scraper into contact with the surface of the material to be rolled. I found out that I can.

  The present invention has been made based on the above idea, and has the following features in order to solve the above problems.

  [1] The high pressure water having an injection pressure of 10 MPa or more is injected from the injection nozzle to remove the scale generated on the surface of the material to be rolled, and the high pressure is applied by a scraper installed on the material conveying line upstream of the injection nozzle. A descaling method for recovering water, wherein a relationship between a distance from a material to be rolled at the scraper position and an amount of the high-pressure water scattered upward is obtained in advance, and the high-pressure water is recovered based on the relationship A descaling method comprising adjusting a gap between the lower end of the scraper and the surface of the material to be rolled so that the rate becomes 80% or more.

  [2] An injection nozzle for removing the scale formed on the surface of the material to be rolled by injection of high-pressure water having an injection pressure of 10 MPa or more, and a target of the injection nozzle for recovering water injected from the injection nozzle. It is a descaling equipment provided with a scraper installed on the upstream side of the rolling material conveyance line, and provides a gap Sg between the lower end of the scraper and the surface of the material to be rolled, and high pressure injected from the injection nozzle A descaling facility characterized in that the distance Ls in the direction of the material to be rolled between the position where water collides with the surface of the material to be rolled and the lower end of the scraper, and the gap Sg satisfy the following equation.

100mm ≦ Ls ≦ 700mm
tan ⁻¹ (Sg / Ls) ≦ 0.8 °

  In the present invention, since an appropriate gap is provided between the scraper and the surface of the material to be rolled, corresponding to the scattering state of the scattered water after colliding with the surface of the material to be rolled, The splashed water after colliding with the surface of the material to be rolled can be accurately collected without wrinkling the material.

  An embodiment of the present invention will be described with reference to the drawings.

  Drawing 1 is an explanatory view of the descaling equipment of hot rolling concerning one embodiment of the present invention. In the figure, 1 is a material to be rolled, 3 is an injection nozzle header, 4 is an injection nozzle for injecting high-pressure water onto the material to be rolled 1, 5 is high-pressure water (injection water) injected from the injection nozzle 4, and 5 'is injection Spattered water after the water 5 has collided with the surface of the material 1 to be rolled, 6 is a scraper provided upstream of the material to be rolled on the material transport line of the spray nozzle 4 to collect the scattered water 5 ', and 20 is a transport table. Laura.

The injection nozzle 4 is inclined by a predetermined angle α from the vertically lower side to the upstream side so as to be injected obliquely from the downstream side to the upstream side of the material to be rolled, and from the injection nozzle 4. A gap Sg is provided from the surface of the material to be rolled 1 above a position separated by a distance Ls from the position A where the jet water 5 collides with the surface of the material to be rolled 1 in the conveying direction of the material to be rolled, and the lower end B of the scraper 6 Is located. That is, β = tan ⁻¹ (Sg / Ls) where β is an angle formed by a line connecting the collision point A of the jet water 5 and the lower end B of the scraper 6 with the horizontal direction.

  In this embodiment, the horizontal distance Ls from the collision point A of the jet water 5 to the lower end B of the scraper 6 and the angle β from the collision point A of the jet water 5 to the lower end B of the scraper 6 are reduced. The expression is satisfied.

100mm ≦ Ls ≦ 700mm
0.5 ° ≦ β ≦ 0.8 °
Here, the reason why the distance Ls is set to 100 mm or more is that since the momentum of the scattered water 5 ′ is strong when the distance Ls is closer, the scraper 6 needs to have a considerably strong structure. On the other hand, the reason why it is set to 700 mm or less is that if it is further away, the facility space becomes too wide.

  Further, the angle β is set to 0.8 ° or less, as will be described later, most of the splashed water 5 ′ is 0.8 ° or more upward from the horizontal direction toward the upstream side of the material to be rolled. This is because most of the scattered water 5 ′ can be recovered by lowering the position of the lower end B of the scraper 6 so that the angle β is 0.8 ° or less. On the other hand, the reason why the angle β is set to 0.5 ° or more is that if the lower end B of the scraper 6 is lowered too much, there is a possibility of coming into contact with the surface of the material to be rolled 1 being conveyed. It is.

  And since the clearance gap Sg between the surface of the to-be-rolled material 1 and the lower end B of the scraper 6 is represented by Sg = Ls · tanβ, for example, assuming that Ls = 300 mm, 0.5 ° ≦ β ≦ 0.8 ° Then, Sg = 2.6 mm to 4.2 mm.

Here, as described above, the result of measuring the scattering state of the scattered water 5 ′ after colliding with the surface of the material 1 to be rolled is shown in FIG. In FIG. 2, the total of the scattered water 5 ′ scattered in the angle direction equal to or greater than the angle θ, with the horizontal axis being the angle θ that scatters upward from the horizontal direction from the collision point A toward the upstream side of the workpiece conveyance line. The relationship between the flow rate Qθ and the flow rate ratio Qθ / Q _T between the total flow rate Q _T of the scattered water 5 ′ is shown on the vertical axis. According to this, at the scattering direction angle θ = 0.8 °, the flow rate ratio Qθ / Q _T = 80%. That is, it can be seen that 80% of the entire scattered water 5 ′ is scattered in the angular direction in which the scattering direction angle θ is 0.8 ° or more.

  Therefore, if the scraper 6 is installed such that the angle β from the collision point A of the jet water 5 toward the lower end B of the scraper 6 is 0.8 °, 80% of the entire scattered water 5 ′ can be recovered. Further, if the position of the lower end B of the scraper 6 is lowered so that the angle β is 0.8 ° or less, 80% or more of the entire scattered water 5 ′ can be recovered.

  In normal descaling equipment, in order to obtain an appropriate descaling effect, it is common to inject high-pressure water with an angle α of the injection nozzle 4 of 10 ° to 15 ° and an injection pressure of 10 MPa or more. However, in that range, the scattered state of the scattered water 5 ′ was not different from that shown in FIG.

  Therefore, by disposing the lower end B of the scraper 6 at the position as described above, in normal descaling, even if the scraper 6 is not brought into contact with the surface of the material 1 to be rolled, 80% or more of the scattered water is scattered. Water can be recovered.

  As a result of changing the recovery rate of the splashed water 5 ′ and observing the temperature drop of the material 1 to be rolled, if at least 80% of the entire splashed water 5 ′ is collected, the material 1 to be rolled by the splashed water 5 ′. In the case where multiple rows of spray nozzles are used in the transport line direction, the scattered water from the downstream spray nozzle and the spray water from the upstream spray nozzle are eliminated. It has been confirmed that the problem that the descaling efficiency is reduced due to the interference with the above can be solved, and the function required for the scraper can be sufficiently achieved.

  In this embodiment, the reason that the angle β is 0.5 ° or more is that the lower end B of the scraper 6 is in contact with the surface of the material to be rolled 1 being conveyed due to the thickness variation of the material 1 to be rolled. This is to ensure a certain interval so that there is no occurrence. Here, when the distance Ls is set to 240 mm in consideration of fluctuations in the thickness of the material 1 to be rolled, warping and undulation of the leading and trailing end unsteady portions, vibration of the material being rolled, etc. Even if the distance between the material 1 and the lower end B of the scraper 6 varies by ± 1 mm, the lower end B of the scraper 6 is prevented from coming into contact with the surface of the material 1 being conveyed. However, if the lower end B of the scraper 6 does not come into contact with the surface of the material to be rolled 1 being conveyed from the equipment arrangement (distance Ls) and the plate thickness accuracy (plate thickness fluctuation), the angle β May be less than 0.5 °. Thereby, the recovery rate can be further improved.

  Thus, in this embodiment, an appropriate gap Sg is provided between the scraper 6 and the surface of the material to be rolled 1 in correspondence with the scattering range of the scattered water 5 ′ after colliding with the surface of the material to be rolled 1. Therefore, the scattered water 5 ′ can be accurately collected with a simple equipment configuration having only one stage of scraper without wrinkling the material 1 to be rolled.

  Further, based on the above concept, a relationship between the distance from the material to be rolled 1 and the amount of high-pressure water 5 scattered upward at the position of the scraper 6 is obtained in advance (for example, FIG. 2). The clearance Sg between the lower end B of the scraper 6 and the surface of the material 1 to be rolled is adjusted so that the recovery rate of the scattered water 5 ′ is 80% or more based on the simple equipment configuration. Splashing water after colliding with the surface of the material to be rolled can be accurately collected without causing wrinkles on the material.

  In order to confirm the effect of the above embodiment, the line connecting the collision point A of the jet water 5 and the lower end B of the scraper 6 is the horizontal direction when a plurality of rows of jet nozzles are arranged in the transport line direction. The angle β formed was changed, and the recovery rate of the scattered water 5 ′ in that case, the scale defect (de-scaling failure), and the generation state of the soot due to the scraper were investigated. At that time, the distance Ls between the collision point A of the jet water 5 and the lower end B of the scraper 6 in the conveyance direction of the material to be rolled is 240 mm, and the angle β is 0.4 °, 0.5 °, 0.8 °, 1 .4 levels of 2 °. Incidentally, the gap Sg between the surface of the material to be rolled 1 and the lower end B of the scraper 6 is Sg = 240 tan β (mm).

  As shown in Table 1, when the angle β is 0.5 ° and 0.8 °, the recovery rate of the scattered water 5 ′ is 80% or more, and the scattered water from the downstream injection nozzles. And the jet water from the upstream jet nozzle are avoided, and a good descaling efficiency is obtained, so that the occurrence of the scale defect due to the descaling failure is suppressed. In addition, even if the gap Sg has a thickness variation, warpage, vibration, etc. (± 1.0 mm) of the material to be rolled, the lower end B of the scraper 6 is a value that does not contact the material to be rolled. There is no occurrence of a pickpocket.

  On the other hand, when the angle β is 0.4 °, the recovery rate of the scattered water 5 ′ is 88%, and the occurrence of the scale defect due to the descaling failure is suppressed, but the gap Sg is the material to be rolled. It is not sufficient with respect to fluctuations in plate thickness, warpage, vibration, etc. (± 1.0 mm), and generation of scratches by a scraper is observed.

  Further, when the angle β is 1.2 °, the recovery rate of the scattered water 5 ′ is less than 80%, and the interference between the scattered water from the downstream injection nozzle and the injection water from the upstream injection nozzle is caused. Therefore, the descaling efficiency is lowered, and the scale defect due to the descaling failure is not suppressed.

  From the above results, the effect of the above embodiment could be confirmed.

It is explanatory drawing of the descaling equipment of the hot rolling which concerns on one Embodiment of this invention. It is a figure which shows the scattering state of scattered water.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolled material 3 Injection nozzle header 4 Injection nozzle 5 Injection water 5 'splash water 6 Scraper 20 Conveyance table roller

Claims (2)

  The high pressure water with an injection pressure of 10 MPa or more is injected from the injection nozzle to remove the scale generated on the surface of the material to be rolled, and the high pressure water is recovered by a scraper installed on the material conveying line upstream of the injection nozzle. In this descaling method, a relationship between the distance from the material to be rolled at the scraper position and the amount of the high-pressure water scattered upward is obtained in advance, and the recovery rate of the high-pressure water is 80 based on the relationship. %. The descaling method characterized by adjusting the clearance gap between the lower end of the scraper and the surface of the material to be rolled so as to be at least%. An injection nozzle for removing the scale generated on the surface of the material to be rolled by jetting high-pressure water having an injection pressure of 10 MPa or more, and the material to be rolled of the jet nozzle for recovering the water jetted from the nozzle. A descaling facility including a scraper installed on the upstream side of the line, wherein a gap Sg is provided between a lower end of the scraper and the surface of the material to be rolled, and high-pressure water sprayed from the spray nozzle is covered with A descaling facility characterized in that the distance Ls in the direction of the material to be rolled between the position of the rolled material that collides with the surface of the rolled material and the lower end of the scraper, and the gap Sg satisfy the following equation.
100mm ≦ Ls ≦ 700mm
tan ⁻¹ (Sg / Ls) ≦ 0.8 °

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