AU619426B1 - Descaling nozzle - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION 42Form Form

(ORIGINAL)

FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: 00 a 0 0 o eo 0o 0 o* a o *00000 0 0 0000 0 00 e 00 o Q 0e Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: KYORITSU GOKIN MFG. CO., LTD.

00 4r 0 16-GO, 12-BAN YAMANAKA-CHO, IMAZU

NISHINOMIYA-SHI

HYOGO-KEN

JAPAN

Actual Inventor: Address for Service: GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: DESCALING NOZZLE.

The following statement is a full description of this invention including the best method of performing it known to me:- 1_KlMT ilrb JHLAUK e <JU_ PATENT AN D TRADE MARK ATTORNEYS MELBOURNE S Y D N E Y P E R T H DESCALING NOZZLE BACKGROUND'OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates to a descaling nozzle used, for example, for jetting out a high pressure fluid water) in band form against a surface of rolled steel plate to remove scales from the surface.

More particularly, the invention relates to a S 10 descaling nozzle having a straightener passage in which a flow straightener is mounted, an orifice, and S' throttle passages arranged coaxially between the ,,straightener passage and orifice and converging toward the orifice, with the orifice opening in the bottom of a groove formed in an end face of the nozzle, 2. DESCRIPTION OF THE RELATED ART A known descaling nozzle as noted above includes a straightener passage in which a flow straightener is mounted, an orifice, and a series of throttle passages arranged coaxially between the straightener passage and crifice and converging toward the orifice (see Japanese Patent Publication No. 1989-111464, for example).

In the known descaling nozzle, the series of throttle passages converging toward the orifice are -1 2.

provided to increase velocity of the fluid straightened in its flow through the straightener passage. However, the straightened fluid tends to become turbulent again as it flows through the throttle passages. This results in a jet of increased thickness emerging from the orifice, which imparts a diminished force of impingement to produce an unsatisfactory descaling effect.

1 0 SUMMARY OF THE INVENTION The present invention has been made having regard to the state of the art noted above, and its object is to provide a descaling nozzle including throttle passages having a devised configuration to minimize turbulence of a fluid flowing through the throttle passages while increasing velocity of the flow through the throttle passages after the fluid is straightened in its flow through a straightener passage.

The above object is fulfilled, according to the present invention, by a descaling nozzle as noted in the introduction hereof and comprising flow straightening passages formed axially intermediate between the throttle passages, the flow straightening passages having substantially the same diameter throughout and extending coaxially over a greater -2i ~u~ length than the throttle passages.

With this construction, a fluid becomes faster and turbulent again as it flows through the throttle passage upstream of the flow straightening passages.

Then the fluid enters and becomes straightened in the flow straightening passages having substantially the same diameter throughout. The presence of the throttle passage downstream of the flow straightening passages presents a resistance to and increases the pressure of the fluid. Thus, the fluid straightened and pressurized in the flow straightening passages enters the downstream throttle passage where the flow is accelerated, to jet out of the orifice.

The downstream throttle passage has the effect of increasing the flow rate of the fluid straightened in the flow straightening passages, while minimizing possibility of the flow becoming turbulent again in its movement through the downstream throttle passage.

Consequently, the fluid jetting out of the orifice has a reduced thickness and an increased force of impingement per unit area, thereby to remove scales efficiently.

Other features and advantages of the present invention will be apparent from the following description.

-3- ~YIII- BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view in vertical section of a descaling nozzle according to the present invention, Fig. 2 is a perspective view of a flow straightener, Fig. 3 is a plan view seen from an end the nozzle having a filter, Fig. 4 is a plan view from a tip end face of the S 10 nozzle, a Fig. 5 is a schematic view of a testing S4Iparatus, SFigs. 6 through 11 are graphs showing distributions of force of impingement in the direction of thickness of a fluid jet, respectively, and Fig. 12 is a graph showing a maximum force of j impingement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A descaling nozzle according to the present invention will be described in detail with reference to the drawings.

Fig. 1 shows a descaling nozzle for jetting out high pressure water against a surface of rolled steel plate to remove scales from the surface. This nozzle -4comprises a dome-shaped filter 2, a first passage forming member 1 having a tubular shape, a second passage forming member 9 also having a tubular shape, and a jet passage forming member 3 screwed to one another in the stated order.

The first passage forming member 1 defines a straightener passage A in which a flow straightener 4 is mounted, a first throttle passage B continuous from the straightener passage A in a downstream direction, and a first flow straightening passage D continuous from the first throttle passage B in the downstream direction. All these passages A, B and D have a common axis X.

The straightener passage A has a cylindrical shape with the same diameter throughout. The first throttle passage B has a shape of a truncated cone /"Oo with a diameter linearly diminishing in the downstream direction over an entire length thereof. The first flow straightening passage D has a cylindrical shape with the same diameter throughout.

The first throttle passage B in this embodiment has the following actual dimensions: passage length: 41.2mm, upstream end diameter: 12.9mm, downstream end diameter 7.6mm, angle 0 of the passage wall to the axis X: about 3 degrees 45 minutes.

The first flow straightening passage D in this embodiment has the following actual dimensions: passage length: 2.8mm, diameter: 7.6mm.

As also shown in Fig. 2, the flow straightener 4 includes a plurality of straightening plates 4A arranged radially and connected to one another. These plates 4A extend along the passage axis X and have a slightly greater length than the straightener passage A. The flow straightener 4 further includes conical projections 4B formed at axially opposite ends of a center core thereof, with the downstream end extending into the first throttle passage B. However, these conical projections 4B are not absolutely necessary, and the number of straightening plates 4A is variable.

The flow straightener 4 will serve the purpose as long as it performs a flow straightening function, and may define a center bore surrounded by a plurality of straightening plates 4A, with the conical projections 4B eliminated.

Outer peripheries of those portions of straightening plates 4A contained in the straightener passage A extend parallel to the passage axis X, so that the outer peripheries are in contact with ins' -e walls of the straightener passage A over the entire length of the outer peripheries. Outer peripheries of -6- I j -i I- the straightening plates 4A lying in the first throttle passage B are inclined toward the axis X as they extend downstream, so that these outer peripheries are in contact with inside walls of the first throttle passage B over the entire length of the outer peripheries.

The straightening plates 4A of the flow straightener 4 in this embodiment has a 16mm actual length where the first throttle passage B has the actual dimensions cited above.

cAs shown in Figs. 1 and 3, the filter 2 resembles a cap, with a dome-shaped plate material defining a o plurality of vertical slits 2A extending from positions adjacent an upper end to positions adjacent a lower end thereof and distributed equidistantly in the circumferential direction. The filter 2 is .srewed to the passage forming member 1 to cover an upstream region of the flow straightener 4.

The second passage forming member 9 defines a second flow straightening passage E continuous from the first flow straightening passage D on the same passage axis X. As does the first flow straightening passage D, the s cond flow straightening passage E has a cylindrical shape with the same diameter throughout.

The second passage forming member 9 is screwed to the -7- I downstream end of the first passage forming member 1 to render the first flow straightening passage D and second flow straightening passage E continuous.

The second flow straightening passage E in this embodiment has the following actual dimensions: passage length: 46.8mm, diameter: 7.6mm which is the same as the diameter of the first flow straightening passage D.

The jet passage forming member 3 includes a nozzle case 3A screwed to the downstream end of the o *second flow straightening passage E, a nozzle chip 3B formed of a wear-resistant hard metal which is press fit in a forward end of the nozzle case 3A and retained in place by a stepped portion 3b, and a bush 3C press fit in the nozzle case 3A. A groove 3a is formed to extend diametrically of forward end faces of the nozzle case 3A and nozzle chip 3B. The nozzle chip 3B defines a jet passage C2 with an orifice C1 thereof opening in the bottom of the groove 3a in a substantially elliptic shape extending longitudinally of the groove 3a as shown in Fig. 4.

The bush 3C defines a second throttle passage C continuous from the downstream end of the second flow straightening passage E, and a third flow straightening passage F extending from the downstream -8- ~-mll^ il~~ I- end of the second throttle passage C to the upstream and of the jet passage C2. These passages also are formed on the same passage axis X. The second throttle passage C has a shape of a truncated cone with a diameter linearly diminishing in the downstream direction over an entire length thereof. The third flow straightening passage F has a cylindrical shape with the same diameter throughout.

The second throttle passage C in this embodiment S 10 has the following actual dimensions: passage length: 4 o 0 12.5mm, upstream end diameter: 7.6mm, downstream end 0 diameter 7.1mm, angle d. of the passage wall to the 0 o O axis X: about 1 degree 8 minutes. The third flow straightening passage F has the following actual dimensions: passage length: 10.0mm, diameter: 7.1mm.

The jet passage C2 has a 7.1mm diameter at a portion 0, thereiof connected to the third flow straightening passage F.

The passage length, downstream end diameter, and angle o of the passage wall to the axis X of the second throttle passage C, the passage length and diameter of the third flow straightening passage F, and the diameter of the jet passage C2 should desirably be varied in accordance with flow rates of the fluid.

-9- ~II The descaling nozzle is mounted in an adapter 6 attached like a branch pipe to a main conduit 5, with the filter 2 lying inside the conduit 5. The nozzle case 3A includes, as integral parts thereof, a flange 3A1 for contacting an end face of the adapter 6 through a packing 7 to hold the descaling nozzle against axial movement, and rotation stopper projections 3A2 engaging grooves Ga defined in inside walls of the adapter 6. The flange 3A1 is fixedly pressed against the end face of the adapter 6 by a cap nut 8 screwed to the adapter 6.

Experiments carried out on che descaling nozzle of the present invention will be described next.

A testing apparatus as shown in Fig. 5 was used in the experiments. This apparatus included a header acting as the main conduit 5 and connected through a turbulence stimulating reducer 11 to a laminar flow pipe 15 having a 41.2mm inside diameter and a length, and a Bourdon gauge 12 attached to the pipe 15. The descaling nozzle was attached to the header through the adapter 6. In the experiments, variations were made in the number N of vertical slits 2A formed in the filter 2, slit length P along the passage axis X, slit width M, and total length L of flow straightening passages which is a sum of the s .1

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passage lengths of the first flow straightening passage D and second flow straightening passage E.

Jets were directed against lead plates 13 with the 2 basic conditions of jetting pressure: 120kg7/cm flow rate: 106.6 litre/min., and jetting distance 300mm.

Grooves 14 formed on the lead plates 13 by impingement of the jets were measured to determine distributions of force of impingement and maximum forces of impingement Fmax (unit: gf) in the direction of thickness T of the jets in a 7mm range midway in the direction of width of the jets.

The maximum force Fmax is based on a circular area of 1mm4, and represents a mean value of results of six tests conducted under the same condition.

Figs. 6 through 8 show measurements of the distributions and naximum force Fmax (unit: gf) of impingement obtained from N 18, P 35.4mm and M L being 2.8mm, 27.8mm and 49.6mm, respectively.

Figs. 9 through 11 show measurements of the distributions and maximum force Fmax (unit: gf) of impingement obtained from N 12, P 30.1mm and M L being 2.8mm, 27.8mm and 49.6mm, respectively.

Fig. 12 shows measurements of the distributions and maximum force Fmax of impingement obtained from descaling nozzles having two different slit widths M.

-11- The horizontal axis represents the total flow straightening passage length L (unit: mm) and the vertical axis the maximum force Fmiax of impingement (unit: gf).

These results show that the greater the total flow straightening passage length L is, the greater becomes the maximum force Fmax of impingement. Also, it is seen that the nmaximum force Fmax of impingement increases with decrease in the slit width M, increase in the number N of the vertical slits 2A, and increase in the slit length P along the passage axis X.

Preferably, the width of the vertical slits 2A is in the range of 0.3 to 3mm for practical purposes.

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Claims (8)

1. A descaling nozzle comprising; a flow straightener, a straightener passage having said flow straightener mounted therein, throttle passages arranged coaxially with and between said straightener passage and an orifice formed at a tip end of the nozzle, said throttle passages having jLameters diminishing toward said .I orifice, 1 0 characterized in that said orifice opens in a bottom of a troove formed on a tip end face of the nozzle, and flow straightening passages are formed axially intermediate between said throttle passages, said flow straightening passages having substantially the same diameter throughout and extending coaxially over a greater length than said throttle passages.

2. A descaling nozzle as claimed in claim 1, characterized in that said flow straightener includes a plurality of straightening plates arranged radially and connected to one another, said straightening plates having a slightly greater length than said -13- straightener passage.

3. A descaling nozzle as claimed in claim 2, characterized in tha'. said flow straightener further includes conical projections formed at axially opposite ends of a center core thereof,

4. .1 descaling nozzle as claimed in claim 2 or 3, characterized in that said orifice has a substantially elliptic shape extending longitudinally of said o groove.

A descaling nozzle as claimed in claim 4, characterized in that a filter is mounted upwardly of said straightener passage to cover an upstream region of said flow straightener.

6. A descaling nozzle as claimed in claim characterized in that said filter is a cap-like element including a plurality of vertical slits extending from positions adjacent an upper end to positions adjacent a lower end and equidistantly distributed circumferentially of a dome-shaped plate material. -14-

7. A descaling nozzle as claimed in claim 6, characterized in that each of said slits has a width ranging from 0.3 to 3mm.

8. A descaling nozzle as claimed in any one of claims 4 to 6, characterized in that said descaling nozzle is mounted in an adapter attached like a branch pipe to a piping, with said filter lying inside said piping, DATED THIS 2ND DAY OF JULY 1991 KYORITSU GOKIN MFG. CO., LTD. By its Patent Attorneys: GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia SI Ii