US3543775A - Apparatus for cleaning hot rolled steel - Google Patents

Description

United States Patent [72] Inventor [54] APPARATUS FOR CLEANING HOT ROLLED [50] Field of Search [5 6] References Cited UNITED STATES PATENTS 1,539,993 6/1925 Conley et al 134/64X 1,918,207 7/1933 Grobstein et al. 134/122UX 2,348,232 5/1944 Trautman et al. 134/1 22X 2,357,695 9/1944 Skowron 1 34/1 7X 2,359,088 9/1944 Croft 134/9 2,394,514 2/1946 Evans et a1. 134/17X 2,418,386 4/1947 Wood 134/122X 2,900,992 8/1959 Johnson 134/122 3,082,774 3/1963 Benton et al... l34/64X 3,129,712 4/1964 Thomas l34/64X Primary Examiner-Morris O. Wolk Assistant Examiner.loseph T. Zatarga Attorney-George A. Rolston ABSTRACT: Apparatus for cleaning strip metal such as hot rolled steel and the like to remove impinged shot and scale and also to remove grease and dirt by means of a very high pressure water spray and a water rinse, and a method of cleaning such strip metal by means of subjecting such strip metal to very high pressure water sprays raked at an angle to the path of movement of the metal, and also directed from the centre line of said strip in a fan shaped manner outwardly across the surface of the metal towards the side edges of the strip so as to provide an outwardly sweeping action of the water flowing over the surface of the metal.

Patented Dec. 1, 1970 Sheet g of 3 mm mm mm a Q. K 5 mm ow 2 m w.

INVENTOR ERNEST R. BODNAR Patented. 1, 1970 Sheet of 3 FIG INVENTOR ERNEST R. BODNAR 7 BY @flfl FIG 6 APPARATUS FOR CLEANING HOT ROLLED STEEL The present invention relates to apparatus for cleaning steel in the form of a continuous moving strip or piece of sheet and is concerned primarily with cleaning the strip after scale has been removed therefrom and is a Continuation-ln-Part of copending application, Ser. No. 611,285 filed Jan. 24, 1967, now abandoned.

When a strip of hot rolled steel comes from a rolling mill it ordinarily is covered by scale and other foreign matter. It has long been recognized that this scale must be removed prior to cold rolling operations. Various methods and apparatus have been provided for this purpose such as blasting and pickling; and successive blasting with metallic shot and grit. However, after such scale removal it is desirable, if not essential, to thoroughly cleanse the surface of the strip.

With this condition in mind the present invention has in view, as its foremost objective, the provision of such cleansing apparatus.

Another object of the invention is to provide cleansing apparatus of the type noted which includes, a high-pressure hydraulic spray tank, a hot water rinse tank and an air dryer, all successively arranged to be effective on the continuously moving strip in sequential order.

More in detail, the invention has as an object, the provision in cleansing apparatus of the type noted, of a high-pressure hydraulic spray tank including two horizontally arranged banks of spray nozzles between which the strip passes, means to recirculatc water in the tank and deliver it under high pressure to the spray nozzles, an overflow outlet, a supply of makeup water, and a bypass associated with the circulating system.

Still another object is to provide, in apparatus of the character aforesaid, a hot water rinse tank adapted to be primarily heated by gas and which includes a hot air conduit passing underneath the tank for supplemental heat and accurate control of the temperature thereof, together with a domelike cover mounted over the tank in spaced relation thereto and provided with an exhaust for vapors emanating from the tank.

Various other more detailed objects and advantages, such as arise in connection with carrying out the above noted ideas in a practical embodiment, will in part become apparent, and in part be hereinafter stated as the description of the invention proceeds.

For a full and more complete understanding of the invention reference may be had to the following description and accompanying drawings, wherein:

FIG. 1 is a side view, largely diagrammatic, of the cleaning apparatus of this invention;

FIG. 2 is a top plan view, also largely diagrammatic;

'FIG. 3 is an enlarged schematic plan view of the high-pressure spray showing a preferred spray pattern;

FIG. 4 is a side elevation of the structure of FIG. 3;

FIG. 5 is a diagrammatic view in plan of a further embodiments; and

FIG. 6 is a diagrammatic side elevation of the structure of FIG. 5.

Referring now to the drawing a strip of hot rolled steel is shown at 10. It will be understood that the strip 10 moves continuously and has had scale removed therefrom by apparatus that is not a part of this invention, It will also be understood that the invention may, also be employed in the cleaning of steel plate with minor modifications (not shown) in the means for supporting and moving the steel. The cleaning apparatus hereof comprises a high-pressure hydraulic spray tank H, a hot water rinse tank R, and an air dryer D, each of these assemblies being identified in its entirety by the respective reference character. According to a further embodiment the rinse tank may be combined with the spray'tank, as shown in FIGS. 5 and 6.

The tank H includes a bottom 11 supported by a floor 12. Upstanding from the bottom- 11 is a forward vertical wall 13, sidewalls 14 and 15, (FIG. 2) and rear wall 16. Supported by these walls is a top or cover 17. The sidewall 14 is provided with access doors at 18. The intended level of water when the tank is in use is represented at 19. The forward wall 13 is formed with an opening just above the level 19 and an overflow conduit 20 is received in this opening and has an open end within the tank.

The tank sidewall 15 is provided with a pair of openings just above the bottom 12 and recirculating pipes 22 and 23 (FIG. 2) have open ends within the tank with the pipes received in the openings with a sealing fit. The pipe 22 communicates with a low-pressure priming pump 24 driven by a motor 26. From the pump 24 a conduit 27 goes to a header 28. It will be understood that control valves are included at appropriate places to permit removal of any of the elements, as for repair or servicing. Such valves are illustrated but not particularly designated.

The pipe 23 is connected to a second priming pump 29 driven by motor 30 and from the pump 29 a conduit 31 goes to the header 28. The latter is connected to one side of a highpressure pump 32 driven by a motor 33. To the other side of pump 32 a conduit 34 is connected. A fitting 35 communicates with conduit 34 at 36. This fitting is vertically arranged and connected to the upper end thereof is a header 37. A similar header (not illustrated) is connected to the lower end of fitting 35. Pipes 38, 39 and 40, are connected to the header 37 and pass through openings in the tank wall 15. inside the tank the pipes 38, 39 and 40 are connected to an upper bank of spray nozzles 41, 42 and 43. A lower bank of spray nozzles 44, 45 and 46 are connected to the lower header by these pipes corresponding to pipes 38, 39 and 40.

While there are illustrated, three separate pipes for carrying upper and lower spray nozzles it will be understood that in most cases only one such pipe, carrying a sufficient number of nozzles, will be adequate, three pipes being shown here since it may be desirable in some cases to employ different numbers or sizes or nozzles for different applications, i.e. where the width of the steel strip varies, and the like.

In some cases an air curtain (not Shown) may be added which has a confining effect on the high-pressure spray coming from nozzles 41 to 46 inclusive which retains the same within tank I-I although this is generally unnecessary.

An inlet for makeup water is depicted diagrammatically at 53. Its purpose is to make up for water lost during operation and is automatically controlled by a float operated valve. Details of this device are not disclosed because such devices are well known.

The strip 10 passes beneath a guide roll 54 and thence through a pinch roll 55. From the latter it passes through a slot in the wall 13 and between the upper bank of high- pressure spray nozzles 41, 42 and 43 and lower bank 44, 45 and 46. The spray nozzles are angularly directed for counter current spraying onto the strip to achieve the best cleaning effects as described below. The strip 10 emerges from the tank H through a slot in the rear wall 16. It is then passed through pinch rolls 56 which are preferably formed of or coated with rubber or synthetic rubber to provide a squeegee" action similar to a wringer, and a return tray (not shown) is arranged to drain water back into tank H and over a carrier roll 57 to the hot water rinse tank R.

In order to achieve the most effective cleaning action it is necessary that high pressures be employed, and that the jets be directed at an angle to the strip. For the purposes of this invention high pressures are defined herein as pressures in excess of about 600 p.s.i., and pressures as high as 2000 p.s.i. or more may be employed with advantage. Water flow should preferably be from 10 to 30 gallons per minute from each noz zle, the nozzles being spaced so that approximately one gallon per minute is applied over between 5-10 square feet of steel. Given suitable pressures and nozzle pattern it is found that the invention can effectively clean steel moving at speeds of 2000 feet per minute or more. The angle or rake of the nozzles, and the spray pattern, is shown in FIGS. 3 and 4. Each nozzle is preferably raked so that when viewed in side elevation (FIG.

4) they are between and 60 relative to the plane of the steel and directed counter current to the direction of movement. In addition the nozzles are preferably arranged on their pipe 41 in a fan shaped manner when viewed in plan (FIG. 3) so that the jets apply an outwardly sweeping action to the steel surfaces. Each nozzle is preferably arranged to develop a jet of between and 30 spread which provides an overlap at the steel surface to ensure complete coverage. When arranged in this way it is usually found to be possible, to completely dislodge impacted shot and any remaining scale, or to remove the heavy grease from cold rolled steel, while using only one such pipe 41 on each side of the steel, At this point it will be noted that the invention has been described with reference to upper and lower surfaces, but it is equally applicable to treatment of steel being supported in a vertical plane, and must be so understood.

It has been found that if pressures substantially lower than 600 psi. are employed the cleaning action is incomplete and generally speaking, at pressures over 600 p.s.i. flow rates greater than about 30 gallons per minute at each nozzle are wasteful and unnecessary. As stated the nozzles should be raked at least 10 to provide counter current jets and when they approach the vertical the cleaning action becomes incomplete.

The tank R comprises an elongated, narrow shallow vat 58 supported by legs 59 from floor 12. The vat 58 includes a bottom 60 which of course determines the bottom plane of water in the tank. The top level is represented at 61.

Spaced inwardly from each end of the vat 58 are a pair of uprights 62, one of each pair being positioned on one side of the vat and theother of that pair on the other side. The uprights 62 are supported from the floor l2 and between each pair a guide roll 63 is pivotally mounted as indicated at 64. It is notable that the lowermost points of the rolls 63 are below the water level 61. The strip 10 passes over carrier roll 57 and below the guide rolls 63 which maintain the strip below the water level 61. Heating conduit means having an inlet at 65 and an outlet at 66 is positioned beneath the bottom 60 of the vat to supply heat, by means of which the temperature of the water may be accurately controlled.

It will be understood that such heat will generally only be required to ensure that the water is hot prior to operations, since the steel itselfwill usually still be hot enough to maintain such water at the desired operating temperature.

As the strip passes through the water tank R it agitates such water and the strip undergoes a washing and rinsing action in which the loosened shot and scale are washed away and fall to the bottom of the tank.

A domelike cover 67 is supported in spaced relation over the vat 58 by supports 68 which rest on the tank sides. An exhaust conduit 69 extends upwardly from the central part ofthe cover 67 and an exhaust fan may be included in the construction thereof at the zone 70.

The strip 10 passes beneath the guide roll 63 at the exit end and thence to pinch rolls 71 which are preferably formed of or coated with rubber or synthetic rubber to provide a squeegee action similar to a-wringer, and a return tray (not shown) is arranged to drain water back into tank R and also from the dryer D. The latter is supported from the floor 12 at strip level by a stand 72 and includes a blower 73 driven by a motor 74 (see FIG. 2). From the blower 73 a duct 75 goes to a manifold 76. An upper bank of knifelike air nozzles are designated 77, 78 and 79. They are all arranged on the same level and connected to the manifold 76 by conduits 80, 81 and 82. A lower bank of similar nozzles is shown in FIG. 1 as comprising nozzles 83, 84 and 85. Brackets 86 and 87 support the two banks of nozzles from the stand 72 in the arrangement illustrated.

From the dryer D the strip 10 passes over a carrier roll 88 and under roll 89 for subsequent handling.

According to a further embodiment of the invention shown in FIGS. 5 and 6 the rinse tank R may be dispensed with and a rinsing action may be induced with the spraying action in a common tank H which is preferably about double the length of the tank H of FIG. 1. In this embodiment the high-pressure spraying action is carried on as before. and the rinsing action is performed above tank water level by low-pressure flooding of large quantities of water from both sides of the steel to float off and wash away the loosened shot and scale. For this purpose one or more large diameter pipes 90 are provided on each side of the path of the steel having nozzles 91 arranged therealong directed substantially normal to the plane of the steel, connected to a pump 92 having a large flow capacity which in turn draws water through filter 93 from tank H by means of pipe 94. This combination of high-pressure spray and low-pressure rinse is found to be highly effective and capable of operation at high speeds. In addition the fact that the invention employs water as the washing medium means that the only residue that must be disposed ofis scale and shot, whereas in the prior art the acid cleaning processes consumed large quantities of acid which must then be reclaimed, or disposed of in some relatively expensive manner.

It is evident that the above apparatus is effective to thoroughly clean and dry the strip after descaling and prepare it for subsequent cold rolling operations.

The water in the spray tank is cool or at ambient temperature whereas the water in the rinse tank is hot, preferably at a temperature of about F. This relation of the respective temperature is believed to materially aid in the cleaning ac tion.

While the invention has been described particularly as used on hot rolled steel after it has been descaled it is also believed that it will find utility when used on cold rolledsteel strip particularly if grease should be present on the strip from the cold rolling operation. Such grease materially impairs the descaling operation.

The subject apparatus in its entirety, as well as components thereof, will also find utility between any uncoiler and recoiler of a continuously moving element such as a strip or wire and also on a rewind line, and for use with steel plate.

While a preferred specific embodiment of the invention is hereinbefore set forth it is to be clearly understood that the invention is note to be limited to the exact constructions, mechanism and devices illustrated and described because various modifications of these details may be provided in putting the invention into practise within the purview of the appended claims.

Iclaim:

1. Apparatus for cleaning a continuously moving strip element having right and left edges and two sides by high-pressure water spray and comprising: a tank defined by a bottom, sidewalls and a roof adapted to contain water at a predetermined level intermediate said bottom and roof; said walls being formed with an entrance aperture and an exit aperture through which said element passes on a predetermined path; a first bank of spray nozzles within said tank on one side of the path of said said element oriented to establish a predetermined zone of high-pressure water spray on a first side of said element angled relative thereto directing spray from said bank of nozzles onto said side countercurrent to said continuously moving element, the majority of said nozzles being arranged in separate right and left groups, said right group being angles outwardly to direct spray across said side towards said right edge of said element and said left group being angled outwardly to direct spray therefrom across said side towards said left edge of said element; a second bank of spray nozzles within said tank on the other side of the path of said element oriented to establish a predetermined zone of high-pressure water spray on a second side of said element angled relative thereto directing spray from said bank of nozzles onto said side countercurrent to said continuously moving element. the majority of saidnozzles being arranged in separate right and left groups, said right group being angled outwardly to direct spray across said side towards said right edge of said element and said left group being angled outwardly to 'direct spray therefrom across said side towards said left edge of said element; drain means communicating with the interior of said tank below said water level for returning water therein to a water supply pipe; a power driven high-pressure pump connected to said water supply pipe; header means connected between said high-pressure pump and said spray nozzles; and water rinse means arranged in the path of said element after the same leaves said high-pressure zone.

2. Cleaning apparatus as claimed in claim 1 wherein said nozzles are raked at an angle between and 60 of the plane of said predetermined path and directed countercurrent to the direction of movement of said element.

3. Cleaning apparatus as claimed in claim 1 wherein said high-pressure pump is adapted to supply water to said nozzles at a pressure of between 600 and 2000 psi.

4. Cleaning apparatus as claimed in claim 1 wherein said water rinse means comprises at least two further banks of spray nozzles located one 60 each of said predetermined path of said element, low-pressure pumping means connected to said further banks of nozzles, collecting tank means located below said predetermined path of said element, and means connecting said collecting tank means to said low-pressure pumping means.

5. The cleaning apparatus ofclaim 1 wherein said spray nozzles deliver said spray at ambient temperature and wherein said water rinse means comprises a hot water rinse tank and heating means therefor and having a predetermined water level and roller means guiding said strip therethrough below said level.

6. The cleaning apparatus of claim 1 wherein said water rinse means comprises a hot water rinse tank; and an air dryer, said tank containing said spray nozzles, rinse tank and dryer being in sequential alinement.

7. The cleaning apparatus of claim 1 including, an overflow drain immediately above the water level of said spray tank, and means to supply makeup water to said spray tank.

8. The cleaning apparatus of claim 1 including resilient pinch roll means arranged in the path of said continuously moving element adjacent the exit thereof from said tank for removing excess water from said element, and means for returning said excess water to said tank.

9. The cleaning apparatus of claim 1 wherein the majority of said nozzles are arranged in right and left groups, as aforesaid, and including an intermediate nozzle in each said bank located between said right and left groups, said nozzles in each said bank being arranged in a generally fan-shaped manner whereby to cause water flowing from said nozzles to move in an outwardly sweeping action over the respective said side of said element, towards the respective said edges thereof.

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