EP0101224A2

EP0101224A2 - Water jet nozzle assembly

Info

Publication number: EP0101224A2
Application number: EP83304367A
Authority: EP
Inventors: Sadao Ebata
Original assignee: Kawasaki Steel Corp
Current assignee: JFE Steel Corp
Priority date: 1982-08-10
Filing date: 1983-07-28
Publication date: 1984-02-22
Also published as: FI73001B; FI832833A; EP0101224A3; AU1747983A; DE3375647D1; AU546810B2; FI73001C; EP0101224B1; FI832833A0

Abstract

A water jet nozzle assembly comprises a hollow cylindrical header being supplied with cooling water under pressure and formed in its both sides with a series of apertures, and two elongated curved plates having a substantially quadrantal cross-section secured to the header with one longitudinal sides of the plates adjacent to lower edges of the apertures formed in the header and with the other longitudinal sides of the plates upward extending.

In the other aspect of the invention, a water jet nozzle assembly comprises a U-shaped trough-like header, an elongated curved plate having a substantially semicircular cross-section formed in its bottom with a plurality of apertures with substantially equal intervals and arranged on the trough-like header so as to close an upper open side of the trough, with longitudinal sides of the curved plate upward extending, and converter plates arranged above and spaced apart from the respective apertures formed in the curved plate to turn water flows jetted from the respective apertures into substantially horizontal directions.

The water jet nozzle assembly according to the invention is able to effectively cool undersides of materials such as steel plates or strips.

Description

This invention relates to a water jet nozzle assembly, and more particularly to a nozzle assembly for jetting cooling water against undersides of materials such as steel plates and the like for cooling the materials.
In steel manufacture, steel plates have been treated to improve their mechanical properties by rapidly cooling them from high temperature or red heated condition, so-called "hardening" or "quenching" or rapid cooling treatment. In this treatment, cooling water is jetted against upper and under surfaces of steel plates to be cooled. In this case, particular precautions must be taken in order to cool the undersides of the plates effectively.
The cooling water jetted from nozzles onto upper surfaces of steel plates will stay thereon for required period of time, so that the overall upper surfaces are cooled in a substantially uniform and effective manner. In contrast herewith, on the undersides of the steel plates, however, the cooling effect occurs only at locations of the surfaces the jetted water initially impinges. After the water has impinged against the surfaces, it immediately drops away from the surfaces and thereafter it does not serve to cool the surfaces. It is therefore difficult to cool the undersides of the plates uniformly and effectively.
There have been various kinds of nozzles of the prior art such as spray nozzles, circular opening nozzles, laminar flow nozzles and the like. These nozzles have more or less encountered such a problem. How to solve this problem has been expected for many years.
Moreover, in cooling steel plates such as strip mill lines, it is difficult to arrange cooling nozzles under the plates to be cooled because of a short distance between table rollers on which the plates are trained.
It is a principal object of the invention to provide an improved water jet nozzle assembly which solves the problem in the prior art and is capable of effectively and rapidly cooling undersides of materials.
It is another object of the invention to provide a water jet nozzle assembly adapted to be arranged in a small space such as between table rollers for steel strip mill lines without affecting the cooling capacity.
A water jet nozzle assembly for cooling undersides of plate-like materials according to the invention comprises an elongated header in the form of a hollow cylinder having a substantially horizontal axis and being supplied with cooling water under pressure, guide means for guiding water flow jetted in substantially horizontal directions from said header to turn said flow upward toward said material to be cooled, and jetting means for substantially horizontally jetting said water flow from said header.
In a preferred embodiment of the invention, the hollow cylinder is formed in its both sides at a mid level with a plurality of apertures in substantially horizontal alignment with each other with substantially equal intervals to form the jetting means, and the guide means comprises two elongated curved plates having a substantially quadrantal cross-section which are secured to the cylinder with one longitudinal sides of the plates adjacent to lower edges of the apertures formed in the cylinder and with the other longitudinal sides of the plates upward extending.
In a further preferred embodiment of the invention the hollow cylinder comprises a U-shaped trough, the guide means comprises an elongated curved plate having a substantially semicircular cross-section arranged on the U-shaped trough so as to close an upper open side of the trough, with both longitudinal sides of the curved plate upward extending, and the jetting means comprises a plurality of apertures formed in a bottom of the curved plate with substantially equal intervals and converter plates arranged above and spaced apart from the respective apertures with spacers to turn the water flows jetted from said respective apertures of the curved plate into substantially horizontal directions.
The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings.

Fig. 1 is a partially sectional plan view of a first embodiment of the water jet nozzle assembly according to the invention;
Fig. 2 is a side view of the assembly shown in Fig. 1;
Fig. 3 is a cross-sectional view taken along a line III-III in Fig. 1;
Fig. 4 is a sectional view illustrating the cooling operation of the assembly shown in Fig. 1;
Fig. 5 is a partially sectional plan view of a second embodiment of the water jet nozzle assembly according to the invention;
Fig. 6 is a sectional view taken along a line VI-VI in Fig. 5;
Fig. 7 is a cross-sectional view taken along a line VII-VII in Fig. 6;
Fig. 8 is a sectional view illustrating the cooling operation of the assembly shown in Fig. 5; and
Fig. 9 is a cross-sectional view of a third embodiment of the water jet nozzle assembly according to the invention.

Referring to Figs. 1-3 illustrating a first embodiment of the invention, a water jet nozzle assembly 1 mainly comprises a header 2 and guide plates 3. The header 2 is in the form of an elongated pipe having a substantially horizontal axis and having an inner cross-sectional area required to jet supply water substantially uniformly over its length of the pipe. The header 2 is provided at its one end at the right end as viewed in Figs. 1 and 2 with a flange 2a adapted to be connected to a conduit (not shown) for supplying the water under pressure and is closed at the other end by a closure disc 2b.
The header 2 is further formed in its sidewalls with a plurality of apertures 2c in alignment with each other and in parallel with the axis of the header 2. The apertures 2c have diameters of, for example, in the order of 3-10 mm and are arranged with a predetermined interval.
The jetted water from the apertures 2c is turned upward by means of guide plates 3 later described to form upward jet water flow in the form of films or laminates. Although the apertures are shown circular, they may be square, rectangular and the like. Moreover, although directions of jetted water from the apertures are horizontal in this embodiment, they may be oblique relative to the horizontal with some angles.
The guide plates 3 are in the form of elongated plates curved in section as arcs of quadrants, as if they were ones obtained by dividing a circular pipe along its generators into four equal parts. The guide plates 3 are secured to the outer surfaces of the sidewalls of the header 2 with one longitudinal sides of the guide plates adjacent to lower edges of the apertures 2c and with the other longitudinal sides of the plates upward extending.
The guide plates have curved smooth upper surfaces and are secured to the header 2 such that tangential lines to the curved upper surfaces of the guide plates at the lower edges of the apertures are aligned with directions of the jetted water from the apertures 2c. The guide plates may be secured to the header as by welding.
The guide plates 3 serve to turn upward the bar-like water flows jetted from the apertures 2c and to widen the water flows into film-like water flows by gathering together the respective water flows jetted from the apertures.
Referring to Fig.-4 illustrating the operation of the water jet nozzle assembly according to the invention, the water flows W₁ , W₂ and W₃ jetted from the apertures 2c of the header 2 and guided by the guide plates 3 are cooling a material 4 trained on table rollers 5.
The water supplied into the header 2 is jetted from the apertures 2c in horizontal directions and guided and turned along the curved upper surfaces of the guide plates 3 upward toward the material 4 to be cooled. The upward flows unite recovered water flows W₃ later mentioned to form the jet water flows W₁ which impinge against the lower surface of the material 4 to be cooled.
When the jet water flow W₁ collides against the lower surface of the material, the flow W₁ is divided into two halves W₂ and W₃, one of which W₂ flows along the lower surface away from the water jet nozzle 1 to cool the material 4 and then falls and the remaining half flow W₃ flows along the lower surface in a direction opposite to the half flow W₂ to cool the material 4 and then collides against the water flow W'₃ coming from the opposite direction so that the water flows W₃ and W'₃ unite with each other and fall onto substantial center of the water jet nozzle assembly 1 to be recovered. When the united water flows W₃ and W'₃ fall on the center of the water jet nozzle assembly 1, they flow into separate directions along outer surfaces of the header 2 onto the guide plates 3 where they unite new water jets from the apertures 2c, respectively, and are energized by the new water jets to form the water flows W₁ which flow upward toward the material 4.
With this arrangement, the amount of the supplied water or water jetted from the apertures 2c is substantially equal to the amount of the water flow W₂ to be consumed or wasted after used for cooling. Accordingly, the amount of the recovered water W₃ to be reused is also substantially equal to the amount of the water jetted from the apertures 2c. These amounts of water are indicated in the following equation.
(water flow W_I) = (water flow jetted from the apertures 2c) + (water flow Wg) = (water flow jetted from the apertures 2c) x 2
Namely, the water flow cooling a material 4 is twice the supplied water flow.
It has been well known that a cooling rate of a material increases as jetted cooling water increases. Accordingly, the water jet nozzle assembly constructed as above described according to the invention can cool material very effectively and rapidly in comparison with nozzles of the prior art, because of twice amount of jetted water with the same amount of supply water. In one result of measuring the cooling capacity of the water jet nozzle assembly according to the invention, cooling rates of steel plates from temperature 800°C to 500°C with flow rate 500 ℓ/min-m² of the cooling water are approximately 1.5 times those of conventional spray nozzles under the same condition.
In the above embodiment, the jet water flow W₁ is directed vertically upward and the flows W₂ and W₃ are substantially equal in amount, in other words, the reused water ratio is 1 (one), that is, (all amount of flow W₂)/(all amount of supply water flow) = 1. However, guide plates 3 may be in section more than arcs of quadrants, so that the upper edges of the guide plates are directed toward each other as shown in phantom lines in Fig. 3. With this arrangement, the jet water flows W₁ are also inclined toward each other, resulting in (water flow W₃) > (water flow W₂). In this case, it is understood that the reused water ratio is more than one, so that more effective and rapid cooling can be carried out.
With the above embodiment, the header 2 and the two guide plates 3 are arranged side by side in a horizontal line, so that the two jetted waters W₁ directing upward along the inner surfaces of the guide plates 3 are properly spaced apart from each other. The water jet nozzle assembly according to the embodiment is therefore the most suitable for cooling materials as in slabbing mill lines whose table rollers are sufficiently spaced without any trouble for locating such water jet nozzle assemblies therebetween.
With this water jet nozzle assembly, however, between the two guide plates 3 is arranged the header 2 having the relatively large diameter so that the overall width L of the nozzle assembly is substantially large which makes it impossible to use for cooling materials as in strip mill lines whose table rollers are not sufficiently spaced.
Referring to Figs. 5-7 illustrating a second embodiment of the invention suitable for use in the strip mill lines, a water jet nozzle assembly 11 mainly comprises a header 15 in the form of a U-shaped trough, a guide plate 12 and converters 13. The guide plate 12 has a substantially U-shaped cross-section and is substantially horizontally arranged on the header 15 integrally therewith to close an upper open side thereof. The guide plate 12 serves to turn water flows jetted at the bottom of the plate upward in a smooth manner. Its cross-sectional shape may be semicircular, deep U-shaped, or shallow or widened U-shaped. The guide plate is formed in its bottom with a plurality of apertures 12a communicating with an interior of the header 15 for jetting cooling water supplied into the header 15. The apertures 12a are preferably circular having diameters of, for example, 3-10 mm with a predetermined interval. However, the apertures may be square or rectangular or longitudinally elongated slits or the like.
The converters 13 comprise spacers 14 integrally formed therewith which serve to arrange the converters 13 above the respective apertures 12a of the guide plate by welding to form clearances G between the guide plate and the converters. The converters 13 serve to turn the water flows from the apertures 12a into substantially horizontal directions.
The header 15 uniformly distribute the supply water and jet it from the apertures 12a. In this embodiment, the header is shown box-shaped in cross-section directly welded to the underside of the guide plate. However, the shape of the header 15 is not limited to that shown in the drawing.
Referring to Fig. 8 illustrating the operation of the water jet nozzle of the second embodiment, the water flows W₁, W₂ and W₃ jetted from the nozzle are cooling a material 16 trained on table rollers 17.
The water supplied into the header 15 is upward guided through the apertures 12a and divided at the converters 13 into horizontal flows. The horizontal flows turn their directions along the inner surfaces of the guide plate and impinge against the underside of the material 16.
With this embodiment, the water flows W₁, W₂, W₃ and W'₃ flow in substantially the same manner as in the first embodiment with exception of the united water flows W₃ and W'₃ fall onto the converters and flow into separate directions on the converters and onto the guide plate 12 where they unite new water jets from the apertures 12a.
In this embodiment, the water flow cooling a material 16 is twice the supplied water flow in the same manner as in the first embodiment. Accordingly, the water jet nozzle of this embodiment can cool material no less effectively than the first embodiment. In an experiment, it has been found that cooling rate of the water jet nozzle of the second embodiment is also about 1.5 times those of the conventional spray nozzles.
Moreover, the guide plate 12 may be circular in section more than semicircular so that upper edges of the guide plate are directed toward each other as shown in phantom lines in Fig. 7 to inwardly incline the water flow W₁ toward each other, thereby increasing the reused water flows to carry out the more effective cooling as in the first embodiment.
Fig. 9 illustrates a third embodiment of the invention in section which is a slight modification of the second embodiment. A water jet nozzle 31 includes modified converters 33. Each the converter 33 comprises a circular disc and a spacer 34 in the form of a hollow cylinder closed at its upper end by the circular disc and formed with through-holes 34b perpendicular to an axial hole 34a. The spacer or hollow cylinders 34 are inserted and fixed in a plurality of apertures formed in the bottom of the guide plate along its length with a predetermined interval such that the through-holes 34b extend in traverse directions of the length of the guide plate and lower edges of the through-holes 34b are at upper surface of the bottom of the guide plate.
With this arrangement shown in Fig. 9, the water flows guided through the axial holes 34a are jetted through the through-holes 34b into the horizontal directions and further advanced along the inner surfaces of the guide plate 32 changing their directions upward toward a material to be cooled. The flows and cooling operation thereafter are substantially the same as those explained with Fig. 8.
As can be seen from the above description, the water jet nozzle assembly according to the invention is capable of effectively cooling undersides of materials and applicable to cooling zones having not only wider table pitches as in slab mill lines but also narrower table pitches as in strip mill lines.
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details can be made therein without departing from the spirit and scope of the invention.

Claims

1. A water jet nozzle assembly for cooling undersides of plate-like materials, comprising an elongated header in the form of a hollow cylinder having a substantially horizontal axis and being supplied with cooling water under pressure, guide means for guiding water flow jetted in substantially horizontal directions from said header to turn said flow upward toward said material to be cooled, and jetting means for substantially horizontally jetting said water flow from said header.

2. A water jet nozzle assembly as set forth in claim 1, wherein said hollow cylinder is formed in its both sides at a mid level with a plurality of apertures in substantially horizontal alignment with each other with substantially equal intervals to form said jetting means, and said guide means comprises two elongated curved plates having a substantially quadrantal cross-section which are secured to said cylinder with one longitudinal sides of said plates adjacent to lower edges of said apertures formed in said cylinder and with the other longitudinal sides of the plates upward extending.

3. A water jet nozzle assembly as set forth in claim 2, wherein said other longitudinal sides of said curved plates extend upward so as to jet the water flow vertically.

4. A water jet nozzle assembly as set forth in claim 2, wherein said other longitudinal sides of said two curved plates extend upward slightly inclined to each other so as to jet the water flow slightly inclined.

5. A water jet nozzle assembly as set forth in claim 1, wherein said hollow cylinder comprises a U-shaped trough and said guide means comprises an elongated curved plate having a substantially semicircular cross-section arranged on said U-shaped trough so as to close an upper open side of said trough, with both longitudinal sides of said curved plate upward extending, and wherein said jetting means comprises a plurality of apertures formed in a bottom of said curved plate with substantially equal intervals and converter plates arranged above and spaced apart from the respective apertures with spacers to turn the water flows jetted from said respective apertures of said curved plate into substantially horizontal directions.

6. A water jet nozzle assembly as set forth in claim 5, wherein said elongated curved plate is circular in section more than semicircular so as to permit said. both longitudinal sides of the plate to extend upward slightly inclined to each other to jet the water flow slightly inclined.

7. A water jet nozzle assembly as set forth in claim 6, wherein each said converter comprises a circular disc and each said spacer comprises a hollow cylinder closed at its upper end by said circular disc and formed with horizontal through-holes in such directions that the water flow from said apertures formed in said bottom of said curved plate is jetted in horizontal directions traverse to a length of said guide plate when said hollow cylinder is inserted and fixed in said aperture formed in the bottom of said curved plate.