JPH05195271A - Method and device for descaling hot rolling metallic article - Google Patents

Abstract

Method for descaling a hot-rolled metal product in which a liquid agent is sprayed onto the surface of the product in the form of a plurality of coherent jets, parallel with one another and having a diameter of less than 2.5 mm. The set of jets is displaced in an alternating sweeping movement in a direction perpendicular to the displacement of the product. The supply pressure of the jets is less than 75 bar and is preferably between 20 bar and 60 bar. The frequency of the alternating movement is between 5 Hz and 50 Hz. The device comprises a plurality of spraying nozzles (8) directed, parallel with one another, towards the product to be descaled (1), means (6; 9) for supplying the spraying nozzles with pressurized liquid agent, as well as means (10) for imparting to the spraying nozzles (8) an alternating sweeping movement in the transverse direction. <IMAGE>

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for descaling hot-rolled metal products and an apparatus for carrying out the method.

[0002]

BACKGROUND OF THE INVENTION The descaling technique commonly used today is to jet a plane jet of high pressure water onto the surface of a rolled product. This jet is normally stationary and the product to be descaled travels longitudinally in front of the sprinkler. The water jet does not only cover the entire surface of the product, but may also be double covered by the overlap of adjacent water spray pipes.

This technique requires high injection pressures and therefore consumes considerable energy. Furthermore, water is also consumed in large quantities.

[0004]

DISCLOSURE OF THE INVENTION The object of the present invention is to remove the scale equal to or more than that which can be realized by the conventional method,
Moreover, it is an object of the present invention to provide a method which can be operated with lower hydraulic pressure and water consumption than the conventional method.

[0005]

Applicants have observed that correct descaling is possible without spraying pressured water on the entire surface of metal products, but the present invention is based on this unexpected observation. Is. In other words, even if the coverage of the method of the present invention is less than 100%, the result of 100% or more of the conventional method can be obtained. The coverage in this case is defined as the ratio of the surface part of the product which is in direct contact with the pressurized water jet to the total surface of the product.

The descaling method for hot-rolled metal products of the present invention is a method of injecting a liquid agent onto the surface of a product moving in a first direction, but in a compact manner with diameters less than 2.5 mm parallel to each other. The liquid material is jetted in the form of a plurality of jets, and the plurality of jets are moved so as to be alternately scanned in a second direction that is not parallel to the first direction.

As used herein, dense jet means a full jet having a substantially constant cross section. In other words, dense jets do not contain bubbles and do not have turbulence or breaks or increases in liquid veins.

The dense jet of this liquid is 0.8 to 2 m
It is advantageous to have a diameter of m.

In a particular embodiment, the jet is divided transversely to the product to be descaled according to a direction that is not parallel to the direction of travel of the product, but is preferably perpendicular.

The direction of the alternating movement of the dense jets on the descaling surface can in principle be in any direction which is not parallel to the direction of movement of the product. However, this alternating movement preferably takes place in a direction perpendicular to the direction of movement of the product, on the one hand for limiting the number of jets and on the other hand for traversing.

The supply pressure of the jet is less than 75 bar, preferably 20 to 60 bar.

Another feature of the invention is an apparatus for performing the descaling method just described.

The device of the invention essentially comprises a plurality of injection tubes arranged parallel to each other towards the product to be descaled,
It includes means for supplying a pressure liquid agent to the injection pipe and means for alternately scanning the injection pipe in a direction that is not parallel to the moving direction of the metal product.

The injection tube has an outlet orifice with a diameter of less than 2.5 mm, preferably 0.8 to 2 mm.

The spacing of the jet tubes (pas), ie the distance separating the jet tubes with respect to the direction of the alternating movement and the course of the jet tube during this movement, is such that the end jets are descaled at the tip of the scanning stroke. It must be properly adjusted to reach the very end of the product.

In one particular embodiment, the spacing between the injection tubes is 15.
To 80 mm. The distance of 15 mm practically corresponds to the minimum space required for the assembly of the injection tube. On the other hand, if the jet tube distance is 80 mm or more, an extremely long scan must be performed to cover the product to the required degree. In fact, the scanning stroke of the jets, which is based on the amplitude of the alternating movement, must be greater than the spacing of the jets so as not to leave a longitudinal region on the product that is not reached by two adjacent jets. ..

Other features and advantages of the present invention will become apparent from the more detailed description given below by way of example and the accompanying drawings.

FIG. 1 is a plan view showing the position of a prior art plane jet injection pipe, which is divided in the width direction of a strip steel to be descaled.

FIG. 2 is a front view showing the device of the present invention located on a strip steel.

FIG. 3 is a diagram showing a range defined by two adjacent water jets on the surface of a steel product.

FIGS. 4 and 5 are plan views of the strip steel of FIG. 2 and depict regions where two adjacent water jets descale. Jet diameters are different.

1 and 2 are unscaled conceptual diagrams and show only the elements necessary for understanding the present invention.
In particular, although the means for supplying the liquid agent and the means for applying the alternating motion are not shown, these may be of any known type.
The directions of movement of movable elements such as strip steel and injection pipes as well as the circulation direction of the liquid agent are indicated by appropriate arrows.

Although numbers are illustrated in FIGS. 3 and 4, these do not limit the scope of the invention.

FIG. 1 shows a product, in this case a strip steel 1 running longitudinally in the direction of the arrow 2. A fixed jet pipe 3 of a flat jet is arranged above the strip steel, which is divided over the width of the strip steel 1 and is inclined with respect to the moving direction of the strip steel. This arrangement of flat-jet jets is typical of the prior art, but the entire surface of the strip is directly exposed to the descaling liquid, in this case water. The non-negligible part of this surface is further hit twice directly with water due to the overlap of the jet tubes 3. FIG. 1 shows the zone 4 of the surface which is directly hit by each plane jet and the recovery zone 5 is shown by a line shadow. In practice, equipment coverage often reaches 1.1 to 1.3. Typically, the installation is operated with a feed pressure of 110 to 150 bar and a flow rate of 20 to 25 liters per m ^{2 of} strip steel surface. Such an amount of water considerably cools the product to be descaled, especially the strip steel.

FIG. 2 shows an outline of the apparatus according to the modified embodiment of the present invention. FIG. 2 also relates to descaling of the steel strip 1, which is cut in the lateral direction and moves according to the arrow 2. The device comprises a horizontal auxiliary tank 6 which is arranged laterally on the strip 1 and extends substantially over the width of the strip. A vertical tubular opening 7 is attached to this auxiliary tank 6, and this tubular opening 7 faces the steel strip and has an injection pipe 8 at its lower end. Pressure water is supplied to the auxiliary tank 6 by an appropriate means not shown by the arrow.

The assembled device consisting of the auxiliary tank 6, the pipe 7 and the injection pipe 8 is subjected to an alternating motion vibrating about the axis P. This movement is transverse to the direction of movement of the strip 1 and is indicated by the double arrow 10. This movement is, for example, a connecting rod device-a handle (commande a bille mannvel
le).

The distance between the injection pipes, that is, the distance in the width direction of the strip steel, D is 15 to 80 mm. In this embodiment, 2
It is preferably 5 mm. The scan stroke C, ie the amplitude of the lateral alternating movement, is 1 to 2 times the spray tube spacing and is therefore preferably 30 to 160 mm, in this particular case 37.5 mm.

FIG. 2 shows the average position of the device. In operation, this device oscillates alternately from one end of the strip to the other, to the dead end where the endmost position, ie the endmost jet pipe jet, effectively reaches each end of strip 1 and the velocity changes. ..

The jet pipe 8 is a jet pipe of a jet concentrated in a circular shape, and its outlet orifice has a diameter d of 0.8 to 2
mm. This jet has an almost constant diameter over its entire length, and the impact surface on the steel strip surface forms a circle of this same diameter d.

Combining the alternating movement of the injection tube 8 with the longitudinal travel of the strip 1 the impact surface of the water jet draws a sinusoidal range on the strip. Therefore, the surface of the steel strip that is directly hit by the jet exhibits a substantially sinusoidal trajectory, with two adjacent trajectories entering into each other more or less deeply according to the amplitude of the alternating motion of the corresponding injection tubes. The surface area of the product that is directly hit by the jet of diameter d will be n × d × l. l is the length of the trajectory. This part is only a part of the whole surface. That is, the coverage is always less than 100%. Figure 3
2 shows these two sinusoidal loci 11, 11 '. In this case, the diameter d of the jet is 0.95 mm, the inter-jet distance D is 30 mm, and the stroke C is 40 mm. Scanning frequency f
Is 12.4 Hz and the product, ie the billet in this case, moves at a speed v = 0.11 m / sec. The coverage under this condition is 29.8%.

On the other hand, it has been experimentally confirmed that the jet working area is larger than the direct impact surface of the jet on the strip steel. In fact, the width of the trajectory that is descaled by a jet of diameter d is 5d to 10d, depending on the impact pressure of the liquid, the speed of jet movement and the type of scale.

FIGS. 4 and 5 illustrate the surface area of the strip steel which is descaled by two adjacent jets, each having a different diameter.

In FIG. 4, the strip steel 1 has a velocity U from left to right in the figure.
= Move at 0.25 m / sec. Trajectories 11 and 11 ′ drawn by the two injection pipes 8.8 ′ are indicated by broken lines, and operating ranges 12, 12 ′ and 13, 13 ′ of jets discharged from the injection pipes are shown.
Is shown by a solid line. The injection pipe has a pipe interval of 25 mm and a scanning stroke of 37.5 mm in a direction perpendicular to the moving direction of the strip steel 1. Ranges 11 and 11 'are substantially sinusoidal. In this example, the frequency f was selected so that the tangent to the starting point of its sinusoidal angle d = 15 degrees with respect to the direction of movement of the injection tube 8.8 '. Considering the velocity v of the strip steel and the stroke C of the injection pipe, the moving frequency f of the injection pipe becomes 13.5 Hz. In terms of the actual speed of the hot rolled product, it is preferable that the frequency is 5 to 50 Hz in order to keep the distances close enough on the one hand and to limit the mechanical external force of this movable assembly on the other hand. .. 70 mm of pressurized water is supplied to the jet pipe.

In FIG. 4, the outlet diameter d of the injection pipe is 0.85.
mm, and the width L of the trajectory descaled by each injection pipe is 6 mm. Under the above conditions, it has been confirmed that the triangulation areas 14, 14 'remain outside the working area of the jets 8, 8'for each alternation.

In FIG. 5, the diameter d of the injection pipes 8 and 8'is 1.
All conditions are the same as in FIG. 4 except that it was 3 mm. In this case, the width L of each working area is 9 mm. As a result, the triangular areas 14 and 14 'are clearly reduced.

Triangular area 1 by varying one or more parameters of jet diameter d, thus width L, angle α, thus frequency f, stroke C or jet spacing D, feed water pressure P.
It can be easily understood that 4,14 'can be completely erased.

[Brief description of drawings]

FIG. 1 is a plan view showing a position of a prior art plane jet injection pipe, which is divided in a width direction of a strip steel to be descaled.

FIG. 2 is a front view showing the device of the present invention located on a strip steel.

FIG. 3 is a view showing a range defined by two adjacent water jets on the surface of a steel product.

FIG. 4 is a plan view of the strip steel of FIG. 2, illustrating a region where two adjacent water jets descale. Jet diameters are different.

FIG. 5 is a plan view of the strip steel of FIG. 2, illustrating a region where two adjacent water jets descale. Jet diameters are different.

[Explanation of symbols]

1 strip steel 2 traveling direction of strip steel 3 fixed jet pipe 4 fixed jet pipe zone of surface hit by jet 5 recovery area 6 auxiliary tank 7 tubular mouth 8 jet pipe 9 pressure water supply means 10 direction of scanning alternation movement 11, 11 'sinusoidal jet trajectory 12,12' range of jet working area 13,13 'range of jet working area 14,14' triangular area outside jet working area P It consists of auxiliary tank 6, tubular mouth 7 and injection pipe 8. Axis of the device D injection pipe spacing C injection pipe scanning stroke (amplitude of alternating scanning motion) α angle formed by the tangent line at the starting point of the sine curve to the movement direction of the injection pipe v speed of strip steel promotion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Pierre Simon, Belgium 4053 Au Ron Pre 34, Ambourg

Claims (10)

[Claims] 1. A method for descaling a hot-rolled metal product in which a liquid agent is sprayed onto the surface of the hot-rolled metal product longitudinally advancing along a first direction, wherein the hot-rolled metal products have a diameter of less than 2.5 mm and are parallel to each other A method for descaling, characterized in that a liquid agent in the form of a plurality of jets is ejected, and the plurality of jets are alternately scanned in a second direction that is not parallel to the first direction. 2. The descaling method according to claim 1, wherein the liquid jet has a diameter of 0.8 to 2 mm. 3. The descaling method according to claim 1, wherein the moving direction of the liquid agent jet is perpendicular to the first direction. 4. The descaling method according to claim 1, wherein the supply pressure of the liquid agent jet is less than 75 bar, preferably 20 to 60 bar. 5. The frequency of the alternation movement is 5 to 50 Hz.
The descaling method according to any one of claims 1 to 4. 6. A plurality of injection pipes (8) directed in parallel to each other to the product to be descaled (1), a means (6; 9) for supplying a pressurized liquid agent to the injection pipes, and a metal product (1). Descaling method according to any one of the preceding claims, characterized in that it comprises means (10) for transmitting an alternating scanning movement to the jet tube (8) in a direction which is not parallel to the longitudinal travel. A device for carrying out. 7. The outlet diameter of the injection pipe (8) is 2.5 m.
7. Device according to claim 6, characterized in that it is less than m, preferably 0.8 to 2 mm. 8. The distance (D) between the injection pipes (8) is 15 to 8.
Device according to claim 6 or 7, characterized in that it is 0 mm. 9. Device according to claim 8, characterized in that the amplitude (C) of the alternating scanning movement is 1 to 2 times the distance (D) of the injection tube (8). 10. An auxiliary tank (6) equipped with a tubular mouth (7) having an injection pipe (8), characterized in that the alternating movement is transmitted directly to the auxiliary layer (6). The device according to any one of 6 to 9.