KR20090129052A - Structure for preventing surface pollution of hearth roll - Google Patents

Abstract

PURPOSE: A structure for preventing surface contamination of a hearth roll is provided to protect a hearth roll from contamination due to contact with a strip surface. CONSTITUTION: A plurality of hearth rolls(200) are installed in an annealing furnace to transfer strips. A structure for preventing surface contamination of the hearth rolls comprises screw threads(220) which are formed on the hearth roll surface in the longitudinal direction to reduce the contact area with the strips. The screw thread has a width of 10~12mm, a pitch of 140~160mm, and a height of 10~12mm.

Description

Hearth roll surface contamination prevention structure {STRUCTURE FOR PREVENTING SURFACE POLLUTION OF HEARTH ROLL}

The present invention relates to a hearth roll surface contamination prevention structure, and more particularly, to improved hearth, in order to minimize foreign substances such as an oxidation scale attached to the surface of a ceramic hearth roll without interruption of operation in a continuous annealing line of a grain-oriented electrical steel sheet. It is related with a roll surface contamination prevention structure.

The surface of the hearth roll which continuously advances the strip (thickness 0.28 ~ 0.5t) along the line in high temperature condition of 850 ~ 1,300 ℃ when annealing high oriented electrical steel sheet generally used in electric equipment such as ballast. Due to contact with the strip, foreign substances such as oxide scales are attached.

1 is a view illustrating a process in which the strip 21 is transported along a hearth roll 22 installed in the horizontal high temperature annealing furnace 20, and the plurality of hearth rolls 22 are connected to the chain 24 together. It is driven simultaneously by the motor 23.

FIG. 2 shows that the foreign material mark S2 is convexly generated on the surface of the strip 21 under high temperature conditions due to the foreign material S1 attached to the surface of the hearth roll 22.

The foreign material mark generated on the surface of the strip as described above forms a space in the surface of the strip to be insulated in order to ensure insulation, thereby lowering the adhesion of the coating solution, and further during preliminary annealing and core punching for stress relief. Not only the insulation coating layer is easily peeled off, but also the adhesion (drop ratio) between the cores stacked a lot, there is a problem that the eddy current loss occurs.

Conventionally, in order to solve this problem, the same annealing conditions as in the production of the product are continuously set, that is, the heating table 880 ~ 900 ℃, cracking zone 855 ~ 860 ℃, reducing zone 650 ~ 700 ℃, cooling table 150 ~ 300 ℃ , Dew point: 70 to 80 ° C, brushed steel sheet (thickness 0.8 to 0.95t) in an annealing furnace under oxidizing atmosphere gas conditions of about 50 vol% hydrogen and 50 vol% nitrogen, and after stopping the line, the hearth roll was 20 to 30 mpm ( By rotating in the reverse direction (ie, the reverse direction of the strip) at a low speed such as the strip moving distance per minute, the foreign matter adhering to the surface of the hearth roll was removed by the frictional force with the brushed steel plate located at the top of the hearth roll.

However, in this case, softening of the steel sheet material occurs due to repeated use of the brushed steel sheet, which makes it difficult to control the tension of the brushed steel sheet in the annealing furnace and the steel sheet is easily broken during the brushing operation.

In addition, since the brushing operation is performed after the line stops, there is a problem that productivity decreases significantly as the number thereof increases.

In addition, when the brushing operation is frequently performed, there is a problem in that a special coating layer on the surface of the ceramic hearth roll is damaged prematurely, thereby shortening the hearth roll change cycle.

The present invention has been proposed to solve this problem, to reduce the contact area with the strip proceeds by processing the helical protrusion in the hull roll surface to prevent contamination of the heart roll without interruption of continuous annealing line to close contact with the strip surface. There is a problem to provide a hearth roll surface contamination prevention structure to protect the hearth roll is contaminated.

The present invention provides a means for achieving the above object, in a hearth roll structure for preventing the surface contamination of a plurality of hearth rolls installed in the annealing furnace to move the strip; The hearth roll surface contamination prevention structure is characterized in that the plurality of threads in the continuous form in the form of protruding to reduce the contact area with the strip in the longitudinal direction of the hearth roll.

At this time, the screw thread is also characterized in that the width 10-12mm, pitch 140-160mm, protruding height 10-12mm.

In addition, the hearth roll is also characterized by being driven individually by a number of drive motors corresponding thereto.

According to the method as described above, the foreign matter contamination of the surface of the hearth roll in the online state in the high temperature annealing furnace is minimized, thereby reducing the number of brushing operations, thereby increasing productivity, reducing the need for brushed steel sheet and reducing downtime for separate brushing operations. The effect can be obtained.

In addition, since the contamination of the strip is prevented, the insulation coating property, the interlayer eddy current prevention, and the dripping rate of the electrical steel sheet are improved.

Furthermore, cost reduction can be achieved by extending the use period of the hearth roll.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

3 is a perspective view of an exemplary installation of the device according to the present invention, and FIGS. 4 and 5 are exemplary views showing main parts of the device according to the present invention.

As shown in FIG. 3, the apparatus according to the invention, unlike the prior art, is individually installed in all, preferably approximately sixteen, hearth rolls 200 installed in the annealing furnace 100 for strip S gratings. It includes a structure in which the drive motor 210 that can be driven is installed respectively.

That is, in the conventional method, the hearth roll was simultaneously driven in a block unit concept by connecting several drive motors in a chain, but in the present invention, the strips S have a time difference from the adjacent hearth roll 200 through the individual drive motors 210. It is a type that can be individually driven for the mail order.

This is because the hearth roll driven by the block unit concept minimizes the phenomenon that the strip (S) plate is intermittently intermittent when the adjacent block is driven when one block is finished, thereby ensuring the smoothness of the plate, and furthermore, the generated oxidation This is to further increase the efficiency of the separate discharge of the scale.

In addition, even if a defect occurs in the strip (S) mailings to be able to quickly respond to it, for example, because the hearth roll was driven in the unit of the conventional strip (S) at the end point of one block This can be repaired only out of this, but according to the present invention has the advantage that can be repaired immediately in the state that the strip (S) to leave only the corresponding hearth roll (200).

And, the hearth roll 200 according to the present invention, as shown in Figures 4 and 5, the thread 220 having a predetermined size on the surface is protruded.

Since the thread 220 protrudes from the surface of the hearth roll 200, it is possible to minimize the contact area with the strip S that is plated.

At this time, the screw thread 220 is designed with a predetermined width for this purpose because it should not leave a trace on the surface of the strip (S) at the time of contact with the strip (S).

That is, as shown in Figure 5, the width (W) of the screw thread 220 is 10-12mm, and the pitch (P) that is the distance between the valleys and valleys or the floor and floor of the thread 220 is 140-160mm, In addition, the protrusion height (H) of the screw thread 220 is preferably designed to 10-12mm.

The reason for the numerical limitation of the structure of the screw thread 220 is that if the width W of the screw thread 220 is smaller than the above range, the marks left on the surface of the strip S become clear, thereby increasing the defective rate, and the width W. If this becomes larger, the range is preferable because the pitch (P) is reduced to reduce the discharge capacity of the oxidizing scale.

In the case of the pitch P, the above range is most preferable because it is designed to be associated with the width W and is the most efficient interval for oxidizing scale discharge.

In addition, in the case of the protrusion height (H), when the lower part protrudes lower than the above range, a part of the strip (S) that is being plated is in contact with a part of the space of the pitch (P), that is, the portion other than the thread (220) of the hearth roll (200). When it protrudes more than that, and protrudes more than that, since the fluctuation | variation of the strip S is severe and a board | substrate rapidly falls, the said range is the most reasonable.

EXAMPLE

In order to test the effectiveness of the hearth roll according to the present invention, 16 hearth rolls according to the present invention were installed in the annealing furnace, and the sheet was annealed while passing the strip under the same conditions and conditions as before.

However, in the present invention, the hearth rolls were individually driven.

In addition, the strips used in the experiment were 0.04 to 0.07 wt% of carbon (C), 2.5 to 4.0 wt% of silica sand (Si), 0.5 to 0.25 wt% of manganese (Mn), 0.03 wt% or less of phosphorus (P), and sulfur (S). ) Cold rolled steel strip for oriented electrical steel sheet consisting of 0.02 wt% or less, aluminum (Al) 0.1 wt% or less, nitrogen (N) 0.01 wt% or less, remaining Fe and other unavoidable impurities. Set the same annealing conditions as the product production, that is, heating table 880 ~ 900 ℃, cracking table 855 ~ 860 ℃, reducing table 650 ~ 700 ℃, cooling table 150 ~ 300 ℃, dew point: 70 ~ 80 ℃, hydrogen 50vol The experiment was carried out for a long time under the condition that nitrogen gas was injected at a flow rate of 0.2 to 2.0 N㎥ / hr, which is about 50% by volume and 50 vol% nitrogen.

As a result, the service life of the hearth roll according to the present invention was approximately three times longer than the conventional hearth roll.

This is because contaminants such as the oxidized scale transferred from the strip are not easily adhered to the surface of the hearth roll by reducing the contact area between the thread protruding from the hearth roll and the strip that is seated and progressed to approximately 1/10. In addition, it has been found to reduce the pollution cyclically by falling to the bottom of the annealing furnace through the space of pitch P.

In other words, the strip is not directly in contact with the surface of the hearth roll, it is likely to be because it is seated on the thread and only contact the width so that the foreign matter that is stuck to the surface of the hearth roll is eliminated.

1 is a schematic view of the annealing plant according to the prior art,

2 is an exemplary photograph showing the contamination of the hearth roll surface according to the prior art,

3 is a perspective view of an exemplary installation of the device according to the invention;

4 and 5 illustrate the main parts of the device according to the invention.

♧ description of the symbols for the main parts of the drawing ♧

100 ... annealing furnace 200 ...

210 .... Drive motor 220 ... Screw thread

Claims (3)

A hearth roll structure for preventing surface contamination of a plurality of hearth rolls installed in an annealing furnace to move a strip; And a plurality of threads formed on the surfaces of the plurality of hearth rolls so as to protrude a plurality of threads so as to reduce the contact area with the strip in the longitudinal direction of the hearth roll. The method according to claim 1; The screw thread has a width 10-12mm, pitch 140-160mm, protruding height 10-12mm, characterized in that the Hurdle roll surface contamination prevention structure. The method according to claim 1; And the hearth roll is individually driven by a number of drive motors corresponding thereto.

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