HK1133409B - Slurry blasting apparatus for removing scale from sheet metal - Google Patents

Description

Slurry blasting apparatus for descaling sheet metal

Technical Field

The present invention relates to a process for removing undesired surface substances from planar substances in flat or continuous form. In particular, the present invention relates to an apparatus and method for driving a scale removing medium, particularly a liquid/particle slurry, against opposite sides of a sheet metal passing through the apparatus to remove scale from the surface of the sheet metal being processed.

Background

The processed sheet metal is sheet metal that is ready for use in making cold rolled sheet metal and for use in processing some products. Sheet metal of this type is used in the processing of products requiring a full range of sheet steel thicknesses, such as agricultural equipment, automotive parts, steel containers and bed frames.

Before sheet metal is used by manufacturers for processing, it is typically prepared by a hot rolling process. In the hot rolling process, the carbon steel is heated to a temperature above 1500 ° F (815 ℃). The heated steel is passed through successive pairs of opposed rollers to reduce the thickness of the steel sheet. Once the hot rolling process is complete, the temperature is reduced by quenching the treated metal sheet or hot rolled steel, typically in water, oil or a polymeric liquid, all of which are well known in the art. The processed sheet metal is then coiled for storage and transport to the hands of the end user of the processed sheet metal, i.e., the aircraft manufacturer, the automobile manufacturer, the appliance manufacturer, or the like.

In the cooling process step of the hot rolled sheet metal, an iron oxide layer, which is generally called scale, is generated on the surface of the sheet metal due to the interaction of the sheet metal with oxygen in the air and moisture generated in the cooling process. The cooling rate of the sheet metal and the overall temperature drop from the hot rolling process affect the amount and composition of scale formed on the surface of the sheet during the cooling process.

In most cases, before a manufacturer can use the sheet metal, the surface of the sheet metal must be treated to provide a surface suitable for the product to be worked, so that the sheet metal can be, for example, sprayed or coated (coating). The most common method of removing oxides from the surface of a hot rolled or heat treated metal sheet prior to coating the surface of the metal sheet is a process known as "pickling" (pickling). In this oxide removal process, a metal sheet that has been hot rolled and then reduced to ambient temperature is unrolled and drawn through an acid bath to chemically remove scale from the surface of the metal sheet. After descaling by an acid bath, the sheet metal is cleaned, dried, and immediately "oiled" to protect the surface of the sheet metal from oxidation or rusting. The oil provides a film layer barrier to air, thereby preventing exposure of the bare metal surface of the sheet metal to air and moisture. Oiling of the sheet metal immediately after the pickling process is extremely important since the bare metal surface starts to oxidize almost immediately when exposed to air and moisture.

The "pickling" process is capable of removing substantially all of the oxide layer or scale from the treated sheet metal. However, the "pickling" treatment has some drawbacks. For example, the acidic species in acid baths for metal sheets are corrosive; it can be a damaging to equipment, a hazard to people, and an environmentally hazardous, particularly limited chemical substance to store and dispose of. Furthermore, the acid bath stage of the process requires a significant area of the sheet metal handling facility.

Accordingly, there is a need in the industry for an improved apparatus and method for surface treating processed sheet metal that is capable of removing oxides or scale from the surface of the sheet metal without the need for floor space for the prior art "pickling" processes and without the use of hazardous chemicals such as acids.

Disclosure of Invention

The present invention overcomes the disadvantages associated with prior apparatus and methods for removing scale from processed sheet metal by providing a process for removing scale that is simpler and does not require the use of hazardous chemicals. The apparatus of the present invention receives a previously processed "i.e. hot rolled" sheet metal and performs the method of the present invention to remove the entire scale from the surface of the sheet metal. The "metal plate" means all forms of metal plates such as plate-shaped or strip-shaped carbon steel or stainless steel materials.

The apparatus of the present invention may employ a leveler that is capable of substantially flattening or flattening the length of sheet metal received from the coil. The leveler may be a stretch leveler or a roll leveler, or both.

The length of sheet metal is moved from the leveler to the descaler of the apparatus. The descaler includes a plurality of pairs of centrifugal impellers, referred to herein as wheels, arranged together and spaced above and below the length of sheet metal passing through the descaler. The rotating wheel is supplied with an abrasive descaling medium, i.e., a slurry of liquid and particles. The rotating wheels drive the media at high speed against the flat surface of the length of sheet metal and the slurry impacts the sheet metal as it passes through the descaler to remove scale from the surface of the sheet metal.

The apparatus may also optionally include a brusher or sweeper according to Voges patent 6,814,815. In most cases, there is at least one cleaning device for receiving the length of sheet metal from the descaler or the brush section. The brush section rotates the brushes and sprays clean water against the opposite surfaces of the sheet metal and assists in removing residual material from the abrasive treatment of the descaler. The impact of the rotation of the brush on the opposite surface of the sheet metal may also be provided for further adjusting the surface material or surface texture of the sheet metal surface.

The length of sheet metal then passes through a "dryer" that dries or otherwise removes residual liquid from the sheet metal.

The dried length of sheet metal is then optionally immediately passed through a coating apparatus that applies an oil film or other protective layer to the surface of the dried sheet metal to immediately prevent re-oxidation of the surface and to provide lubrication for subsequent processing and to prevent damage from contact between the two metal surfaces in a coil of sheet material that results when the length of sheet material is dried and oiled before it is moved to a re-coiler for coiling back the length of sheet metal. The descaled and oiled coil of sheet material is then in a convenient storage condition until needed for subsequent processing.

The full scale removal process performed by the apparatus of the present invention can complement other sheet processing, for example, the process of U.S. Pat. No.6,814,815, which is capable of controlled removal of a portion of the scale, resulting in a corrosion-inhibiting surface suitable for some products that do not require full scale removal, such as some galvanizing operations.

The descaler apparatus and method provide a new method of removing scale from processed metal that has some commercial advantages over the prior art. The apparatus and method of operation are less expensive to operate than, for example, prior art pickling processes, do not require hazardous substances, and do not leave hazardous cleaning residues on the sheet metal. There is no need to change the speed or other parameters of the process line to remove more stable oxides at the edges of the strip or at the end of the coil where air exposure or longer temperature increases promote oxidation.

The dephosphorizing apparatus can be used independently of the sheet metal processing line speed with relaxed operating time limits without the same disadvantages of line stop, cleaning, or over-pickling of sheet metal, which have been commonly associated with pickling processes. With the new treatment, small surface stains such as debris (slivers) and foam (seeds) can be removed. In the pickling process, loose metal flakes (loose steelflaps) are usually held on the plate, covering a certain area. The flakes fall off during subsequent flattening, coating or annealing operations, which places greater customer obligations on the steel processor.

The apparatus and method of the present invention may also be used for single sided applications.

The apparatus of the present invention and method of use thereof may also be used to control the surface texture of the processed sheet metal material. The apparatus of the present invention may be employed to control the surface texture to achieve a target surface texture. Texture is a key parameter in high add-on products. Board consumers typically specify a strict range of Ra and Rpc values for the purchased board based on the processing and end use of the material. To improve the weight control of coating or zinc adhesion in the media for heavy coating weight galvanizing lines, a higher Ra value in the 150 micro-inch range is required, for example, a 70 micro-inch Ra value with a high peak count is required to improve lubrication in the drawing or stamping process, or to create an attractive surface after final spraying.

The apparatus can also be used to obtain different target textures on opposite surfaces of the strip of sheet metal. This is used in the examples where the interior surface of the part is primarily required to have a thick lubricant film for drawing and a thick polymer coating film for abrasion and corrosion inhibition, while the exterior surface of the part is required to provide an attractive smooth painted surface. This technique has been used in the past for body panels in limousines, but could be used in other applications as well. The ability to adjust the surface texture of the sheet is important because a rough surface texture generally improves the adhesion of the coating, but requires more coating. The adjustment to the texture enables the user of the device to adjust the surface texture depending on which of the desired adhesion or plating amounts is more important.

The apparatus is capable of providing a more uniform surface texture relative to the surface of sheet metal obtained by pickling, which tends to have a mixed topography, particularly in the range of textures known as micro-roughness. The apparatus of the invention can be easily adjusted to efficiently adapt to sheet metal strips of different widths. The width of the spray zone where the slurry contacts the surface of the sheet metal can be reduced for narrower materials, but still substantially the full design energy of the wheels of the apparatus can be used, allowing the sheet metal processing line to process narrower materials at faster speeds.

The use of stainless steel particles in the slurry improves the corrosion characteristics of the metal sheet. This is said to be due to a reduction in free iron ions on the surface of the metal, resulting in passivation of the surface.

The apparatus and method of the present invention provide more consistent performance than dry-sprayed sheet metal because the abrasive particles in the slurry used in the apparatus do not degrade as quickly as the same or equivalent particles used in dry-spraying. The liquid in the slurry used in the present apparatus reduces damage caused by accidental impact between non-targeted abrasive particles, thereby resulting in longer service life of the abrasive particles. Similarly, the liquid reduces wear between the abrasive particles and the equipment components, thereby resulting in longer service life of the equipment components. Also unlike dry spraying, the apparatus of the present invention does not generate dust, thereby providing a more suitable working environment, reducing the risk of fire, and generating less noise in operation.

The apparatus of the present invention also provides a cleaner strip surface than a dry spray process which leaves a series of residues on or embeds residues in the sheet metal surface. These dry spray residues can include metal stains that are very difficult to remove. In addition, surface contaminants that are located on the sheet metal material prior to dry spraying may become embedded in the surface of the sheet metal material. Furthermore, unlike dry blasting, wet spots on the incoming sheet metal strip do not cause the problem of clumping of loose scale or debris on the surface of the strip, which can further cause a series of defects in the strip. The resulting mass may be applied to a strip of sheet metal or to a processing drum in a line.

The problem of dry blasting which would raise the local temperature of the strip of sheet material causing distortion of the strip of sheet material and/or spark rusting of the strip of sheet material does not arise in the apparatus of the present invention.

The apparatus of the present invention is capable of using a wide range of scale removing media, e.g., a wide range of particle sizes, relative to dry blasting. The apparatus of the present invention may also increase the processing options for sheet metal. For example, the surface of the metal sheet may be treated with the slurry with a rust inhibitor as the liquid in the slurry. A cleaning agent may also be added to the liquid of the slurry to degrease or clean the surface of the sheet metal for reprocessing defective material resulting from other processes.

The apparatus of the present invention is capable of distributing the abrasive more evenly across the width of the sheet metal material than other slurry blasting devices. In a preferred embodiment, the slurry stream driven by each wheel of the apparatus covers the full width of the sheet metal.

The apparatus of the present invention is also easily adjustable to accommodate sheet metal of different widths. The apparatus is capable of using its full energy for a wide range of sheet metal widths.

The apparatus is more efficient in terms of energy consumption than a gas injection slurry blasting system. The gas injection system requires multiple discharge nozzles to cover the width of a common industrial sheet material strip. With the present invention, there is no discontinuity at the edge position of the slurry spray pattern of the individual streams contacting the sheet metal and at the overlapping position of the individual patterns or at the beginning and end thereof.

The centrifugal impeller plate descaling apparatus of the present invention also has fewer parts than other slurry blasting apparatuses. The complexity of most of the individual components of the apparatus is also reduced compared to alternative slurry blasting apparatus. Furthermore, for systems with the same total flow sum of slurry, the relative surface area of the components in contact with the moving abrasive in the configuration of the present invention is much smaller compared to other slurry blasting devices, resulting in lower overall wear.

Drawings

Further features of the method and apparatus of the present invention are described in the following detailed description of the invention and in the accompanying drawings.

FIG. 1 shows a schematic side view of an apparatus for descaling processed sheet metal and a method of operating the same according to the present invention;

FIG. 2 shows a schematic top view of the apparatus shown in FIG. 1;

FIG. 3 shows a side view of the descaler of the apparatus shown in FIG. 1;

FIG. 4 shows an end view of the descaler as viewed from the upstream end of the descaler;

FIG. 5 shows an end view of the descaler as viewed from the downstream end of the descaler;

FIG. 6 shows a view of a portion of the descaler as shown in FIGS. 4 and 5;

fig. 7 shows a view of a further part of the descaler as shown in fig. 4 and 5.

Detailed Description

FIG. 1 shows a schematic view of the apparatus of the present invention for performing the method of the present invention for removing scale from the surface of processed sheet metal. As will be explained, the sheet metal passes through the apparatus shown in fig. 1 from left to right in a downstream direction. The constituent parts of the apparatus shown in fig. 1 are the preferred embodiment of the present invention. It will be understood that variations and modifications can be made to the described preferred embodiment without departing from the scope of protection defined by the claims of the present application.

Referring to FIG. 1, a coil of previously processed sheet metal (e.g., hot rolled sheet metal) 12 is positioned adjacent an apparatus 14 to supply the apparatus with a length of sheet metal 16. The roll of sheet metal 12 may be supported using any existing equipment capable of selectively unwinding the length of sheet metal 16 from the roll of sheet metal 12 in a controlled manner. Alternatively, the apparatus may be supplied with sheet metal in the form of individual sheets.

A leveler 18 of the apparatus 14 is positioned adjacent the coil 12 to receive the length of sheet metal 16 unwound from the roll. The leveler 18 is constructed of a plurality of rolls 22, 24 having gaps. Although only a roller leveler is shown, other types of levelers may be used in the apparatus and process of the present invention.

From the leveler 18, the length of sheet metal 16 being processed is transferred into the descaler 26 of the present invention. In fig. 1 and 2, the pair of descaling cells 26 is formed by two pairs of matched centrifugal impeller systems, one pair mounted for processing each of the two planes of the sheet, shown as being arranged in succession in the downstream direction of movement of the sheet metal 16. Since the two descaling cells 26 are constructed in the same manner, only one descaling cell 26 will be described in detail. The number of descaling cells depends on the desired line speed of the apparatus, and ensures adequate scale removal and subsequent surface texture adjustment.

Fig. 3 shows an enlarged horizontal side view of the descaler 26 removed from the apparatus shown in fig. 1 and 2. In fig. 3, the downstream direction of movement of the length of sheet metal is from left to right. The descaler 26 is mainly constituted by a hollow box 28. As shown in fig. 3-5, a portion of the length of sheet metal 16 passes through the descaler box 28. The length of sheet metal 16 is shown oriented in a generally horizontal direction as it passes through the descaler box 28. It should be understood that the horizontal orientation of the sheet metal 16 shown in the drawings is not required for proper operation of the present invention. The sheet metal may be oriented to pass through the descaler apparatus in a vertical direction or any other direction. Thus, terms such as "top" and "bottom", "above" and "below", "upper" and "lower" and the like should not be construed as limiting the orientation of the apparatus or the orientation of the length of sheet metal suitable for operation of the apparatus.

The upstream end wall 32 of the box has a narrow open entrance slot 34 for receiving the width and thickness of the length of sheet metal 16. The opposite downstream end wall 36 of the box has a narrow outlet opening 38 sized to receive the width and thickness of the length of sheet metal 16. Fig. 4 shows the inlet opening 34 and fig. 5 shows the outlet opening 38. The opening has a sealing device designed to retain the slurry in the tank when the sheet material is processed. The descaler box 28 also has a top wall 42, a series of bottom wall panels 44, and a pair of side walls 46, 48 that enclose the interior volume of the box. For clarity, the interior of the box 28 is substantially empty, except for pairs of opposed rollers 52, 54 for supporting the length of sheet metal 16 as it passes through the box interior from the inlet opening 34 to the outlet opening 38. In many cases, a shrink support device is used to assist in threading the end of the sheet through the machine. The bottom of the tank 28 is provided with a drain slot 56 having a drain opening to the interior of the tank. The discharge chute 56 may be used for the outflow of material removed from the length of sheet metal 16 and the collection of used slurry from the interior of the box 28.

A pair of driven centrifugal impellers 68 are mounted in lined shells, shrouds or shrouds 58, 62 provided on the top wall 42 of the box. The shrouds 58, 62 have a hollow interior that can communicate with the interior of the tank through an opening in the tank top wall 42.

As shown in fig. 3-5, the slurry impeller casing shrouds 58, 62 are not arranged side-by-side, but are instead arranged in a staggered arrangement on the top wall of the box 42. This arrangement is to ensure that the slurry discharged from one impeller does not interfere with the slurry discharged from the other impeller of a pair. A pair of motors 64 are mounted on the pair of shrouds 58, 62. Each motor has an output shaft 66 extending through the side wall of the shroud 58, 62 to which it is attached and into the interior of the shroud. The construction and operation of the descaling wheels and associated shrouds is similar to the slurry discharge heads disclosed in the following U.S. patents, inventors No.4,449,331, No.4,907,379, and No.4,723,379 to MacMillan; the inventors of the present invention are No.4,561,220 to Carpenter et al; inventors No.4,751,798 to McDade; and Lehane, No.5,637,029, the above patents are incorporated by reference in this application.

The slurry is discharged from the impeller at a speed in the range of 280 feet per minute. A slurry of water and #20 wire cut pellets may be used in the first descaling unit to optimize the descaling process for the hot rolled carbon steel strip. A series of softer stainless steel shot was used in the second descaler cell to adjust the surface texture produced. Satisfactory results have been demonstrated using a mixture of #30 and #10 pills. If the treated board is not oiled after treatment, a corrosion inhibitor such as that sold under the "Oakite" trademark by Oakite Products inc. The selection of a particular product is based on the subsequent use of the sheet being processed and the level of protection required.

If the surface of the incoming material has oil, commercial alkali or other cleaning or degreasing agents can be added to the water of the slurry without changing the efficiency of the slurry impingement process. Other abrasive media may be selected by those skilled in the art. The average size, size distribution, shape and material of the abrasive material to be mixed into the slurry mixture is determined based on the material of the sheet being processed and the desired surface result/condition.

Rotation of the motor shaft 66 causes rotation of a descaling wheel 68 attached to the shaft. While the motor 62 is used as the preferred drive source for the descaling wheels 68, other means of rotating the descaling wheels 68 may be used.

A second pair of centrifugal slurry impellers 88 are provided on the bottom wall panel 44 of the descaler box 28. The basic function and dimensions of the cell pair are the same as the centrifugal impeller on the top wall.

The shafts of the first and second pairs of impellers 68, 88 and their assembly are mounted on the descaler box 28 in a direction oblique to the direction of the length of sheet metal 16 passing through the descaler box 28. The shafts 98, 102 of the second pair of motors 84 are also inclined to the plane of the length of sheet metal 16 passing through the descaler cell 28. This angle is selected to ensure a stable slurry flow and to reduce interference between rebounding particles and particles that have not yet impacted the sheet surface, as well as to improve the scouring action of the abrasive, to improve the efficiency of material removal, and to reduce the forces that tend to embed the material into the sheet that needs to be removed in subsequent impacts.

The supply of the scale removing medium 104 communicates with each of the shrouds 58, 62 at the center portions of the descaling wheels 68, 84 in the same manner as described in the previously referenced Lehane patent, or in other equivalent manners. The scale removing medium in the preferred embodiment of the invention is a slurry of fine steel particles and water. The supply of the scale removing medium 104 is shown schematically in FIG. 3 to illustrate various known methods of supplying different types of abrasive slurry removal media to the interior of the descaler box 28.

The upper pair of descaling wheels 68 drives the scale removing medium 105 downwardly toward the length of sheet metal 16 passing through the descaling cell 28. With the design of the previously referenced patents, the solid and liquid components of the slurry are effectively targeted at the same area on the sheet, and the driven scale removing medium 105 impacts and removes scale from the upper surface 106 of the length of sheet metal 16. In the preferred embodiment, each wheel of any pair of descaling wheels is turned in opposite directions. For example, if the descaling wheels 68 on the left side of the sheet metal upper surface 106 rotate counterclockwise as the length of sheet metal 16 moves in the downstream direction, the descaling wheels 68 on the right side of the sheet metal upper surface 106 rotate clockwise. This causes each of the descaling wheels 68 to drive the scale removing medium 105 into contact with the upper surface 106 of the length of sheet metal 16, wherein the contact surface of the scale removing medium 105 driven by each of the descaling wheels 68 extends fully across and slightly beyond the width of the length of sheet metal 16. The spraying is allowed to slightly exceed the edges of the sheet in order to ensure the most even coverage. This is illustrated by the two almost rectangular areas of impact 112, 114 of the scale removing medium 105 with the upper surface of the length of sheet metal 16 shown in FIGS. 6 and 7. Since the direction of slurry movement driven by the descaling wheels relative to the width of the strip varies with the location of slurry discharge along the diameter of the descaling wheels, some directional corresponding texture is produced for the location of slurry impact furthest from the descaling wheels. In a preferred embodiment of the invention this is compensated for by using a pair of wheels rotating in opposite directions so that each portion of the sheet first passes through the slurry jet of the first wheel, and all directional effects produced by the slurry of the first jet are then compensated for by the impact of the second jet of slurry ejected from the second wheel, the second jet of slurry having an oppositely balanced cross-sheet velocity component to the first jet of slurry.

The axially staggered position of the upper pair of descaling wheels 68 also axially spaces the two impact regions 112, 114 on the upper surface 106 of the sheet metal. This allows the scale removing medium 105 to impact the full width of the sheet metal without interfering contact between the medium 105 propelled from each of the descaling wheels 68. In addition, the positioning of the pair of descaling wheels 68 and 84 can be adjusted to be away from or close to the upper surface 106 of the sheet metal passing through the descaler. This can provide a second adjustment for different widths of sheet metal material. By moving the motor 64 and wheels 68 away from the upper surface of the sheet metal material, the width of the impact areas 112, 114 with the upper surface 106 of the sheet metal material is increased. By moving the motor 64 and its wheels 68 towards the upper surface 106 of the sheet metal material, the width of the impact areas 112, 114 with the upper surface 106 of the sheet metal material is reduced. This adjustment of the position of the motor 64 and its descaling wheels 68 makes the apparatus suitable for descaling sheet metal of different widths. Another way to width-adjust the slurry impact area of the sheet metal surface is to move the angle of the inlet nozzle 104 relative to the impeller housing/shroud. This approach is described in the patents cited above. A third option is to rotate the impeller pairs about an axis 116 perpendicular to the axis of rotation of the impellers relative to the direction of movement of the sheet material so that the elliptical impact area of slurry from each wheel, while maintaining the same length, is not at right angles to or transverse to the direction of movement of the sheet material. The movement towards or away from the sheet material also changes the impact energy of the slurry stream.

In addition, the angled orientation of the axles 78, 82 of the descaling wheels 68 also causes the impact of the scale removing medium 105 to be angled relative to the surface of the sheet metal 16. The angle at which the impact of the scale removing medium 105 makes with the surface of the sheet metal 16 is selected to optimize the efficiency of the scale removal. An angle of 15 deg. has proven satisfactory.

In addition, adjusting the characteristics of the scale removing medium 104 may be used to adjust the surface texture of the length of sheet metal passing through the descaler. For example, a combination of particle sizes, particle shapes, or particle materials in the slurry of the scale removing medium 104 may be adjusted to produce different desired surface textures on the sheet metal.

As shown in FIGS. 3 and 7, the lower pair of descaling wheels 88 direct the descaling slurry 105 against the lower surface 108 of the sheet metal 16 in the same manner as the upper pair of descaling wheels 68. In this configuration, the area of impact 105 of the scale removing medium to the lower surface 108 of the length of sheet metal 16 is directly opposite the areas of impact 112, 114 to the upper surface of the sheet metal. This balances the load of the slurry flow from the upper and lower portions to which the sheet is subjected, thereby improving the stability of the line tension. Thus, the lower descaling wheels 88 operate in the same manner as the upper descaling wheels 68 to descale the lower surface 108 of the sheet metal 16 passing through the descaler 26.

In the embodiment of the apparatus line shown in fig. 1 and 2, two injection units 26 are arranged in sequence along the path of the metal sheet 16 through the line. After leaving the two spraying units 26, the metal sheet 16 will be further processed.

A brusher (brush) 122 is positioned adjacent the spray unit 26 for receiving the length of sheet metal 16 from the descaler. The brusher 122 may be of the type disclosed in U.S. patent No.6,814,815 to Voges, which is incorporated herein by reference. The brusher 122 is comprised of a plurality of rotating brushes arranged across the width of the sheet metal 16. As the sheet metal passes through the brusher 122, the rotating brushes contained in the brusher 122 contact the opposed upper 106 and lower 108 surfaces of the length of sheet metal 16 and create a unique surface that is sprayed and brushed, typically with a low degree of roughness and with some directionality. The rotating brushes cooperate with the water sprayed in the brusher 122 to treat the opposite surface of the sheet metal to adjust or change the surface texture produced by the spray unit 26.

A dryer 124 is provided adjacent the brusher 122 for receiving the length of sheet metal 16 from the brusher, or directly from the slurry blasting device in the event that a brush unit is not installed or detected. The dryer 124 dries the surface liquid of the length of sheet metal 16 as the sheet metal passes through the dryer. The liquid residue self-cleaning procedure.

A coiler 126 receives the length of sheet metal 16 from the dryer 124 and winds the length of sheet metal into a coil for transport or storage of the sheet metal.

In an alternative in-line arrangement/embodiment, the length of sheet metal processed by the apparatus may be further processed by a coating applied to the surface of the sheet metal, such as a galvanised coating or a paint coating.

The length of sheet metal can likewise be passed a second time through the line system as in figures 1 and 2 and thus be further processed.

It should also be understood that different devices may be used to treat the opposite surfaces of the length of sheet metal, such as by providing different scale removing media to the upper and lower portions of the length of sheet metal passing through the device.

The descalers of the apparatus may be arranged at different positions in the line, instead of in the manner shown in figures 1 and 2. For example, a descaler may be arranged after the brusher.

The above-described dephosphorizer apparatus 14 provides a means for removing substantially all scale from the processed sheet metal (i.e., previously hot rolled or otherwise processed) that requires less floor space and less expense than existing descaling techniques, which primarily involve pickling.

To summarize the basic procedure of the present invention, the length of sheet metal is first flattened to provide a substantially flat surface.

The length of sheet metal is then descaled by subjecting the opposite upper and lower surfaces of the length of sheet metal to a slurry spray through at least one centrifugal pump and a slurry circulation system, typically a slurry of water and particulates. The slurry is driven against the surfaces of the length of sheet metal to descale the opposite upper and lower surfaces of the length of sheet metal.

The water remaining on the length of sheet metal is then dried from the upper and lower surfaces. The descaled sheet metal may then optionally be oiled and then coiled for storage or transport of the sheet metal.

Additional features of the method of the invention include brushing the opposing upper and lower surfaces after the descaling process. The brushing applies a second treatment to the opposite upper and lower surfaces of the length of sheet metal, and optimizes the surface condition by adjusting the surface texture resulting from the descaling process, and provides an alternative way to create two product families from the same equipment.

The treatment according to the invention also has the advantage of being completely environmentally friendly, i.e. without the need for hazardous chemicals required by existing pickling treatment techniques. Likewise, the apparatus and method of the present invention requires only about 100 feet of in-line floor space, as compared to 500 feet of floor space typically required for pickling processes.

Although the method and apparatus of the present invention have been described herein by way of illustration of the preferred embodiments of the invention, it is to be understood that modifications and variations may be made to the basic concepts of the invention without departing from the scope of the following claims.

Claims (29)

1. An apparatus for removing scale from sheet metal, the apparatus comprising:

a descaler that receives each length of sheet metal and removes scale from at least one surface of the length of sheet metal as the length of sheet metal moves in a first direction through the descaler;

a scale removing medium supply mechanism in communication with and supplying scale removing medium to the descaler, the scale removing medium comprising a slurry of liquid and hard-grain based particles;

a pair of wheels on the descaler positioned adjacent at least one surface of the length of sheet metal passing through the descaler, a first wheel and a second wheel of the pair of wheels having first and second axes of rotation, respectively, the first and second wheels positioned on the descaler to receive a descaling medium from the supply of descaling medium; and the number of the first and second groups,

at least one power source operatively connected to the first and second wheels to rotate the first and second wheels such that rotation of the first wheel causes scale removing medium received by the first wheel to be driven from the first wheel across the at least one surface of the length of sheet metal passing through the descaler and rotation of the second wheel causes scale removing medium received by the second wheel to be driven from the second wheel across the at least one surface of the length of sheet metal passing through the descaler;

wherein the first wheel rotates in a first rotational direction and the second wheel rotates in a second rotational direction, the first rotational direction being opposite the second rotational direction;

wherein the second wheel is spaced from the first wheel in the first direction a sufficient distance such that the scale removing medium driven from the second wheel does not substantially interfere with the scale removing medium driven by the first wheel; and is

Wherein the first and second wheels are positioned adjacent opposite side edges defining a width of the length of sheet metal with the length of sheet metal centered therebetween; and

wherein substantially all of the scale is removed from the at least one surface of the sheet metal.

2. The apparatus of claim 1, further comprising:

adjustably positioning the first wheel on the descaler for movement toward or away from the length of sheet metal passing through the descaler; and the number of the first and second groups,

adjustably positioning the second wheel on the descaler for movement toward or away from the length of sheet metal passing through the descaler.

3. The apparatus of claim 1, further comprising:

the first wheel and the second wheel are equidistant from the length of sheet metal.

4. The apparatus of claim 1, further comprising:

the descaler is included as part of a sheet metal processing line that includes a brusher for receiving the length of sheet metal from the descaler.

5. The apparatus of claim 4, further comprising:

the descaler is included as part of a sheet metal processing line that also includes a dryer for receiving the length of sheet metal from the brusher.

6. The apparatus of claim 4, further comprising:

the descaler is positioned adjacent one surface of the length of sheet metal and the brusher is positioned adjacent an opposite surface of the length of sheet metal.

7. A method for removing scale from a length of sheet metal, comprising:

positioning a first wheel having a first axis of rotation adjacent a first surface of the length of sheet metal;

positioning a second wheel having a second axis of rotation adjacent the first surface of the length of sheet metal;

supplying a slurry comprising liquid and hard particles to the first and second wheels as a descaling medium;

rotating the first wheel about the first axis of rotation such that scale removing medium supplied to the first wheel is driven by the rotation of the first wheel toward a first area extending across the first surface of the length of sheet metal; and

rotating the second wheel about the second axis of rotation such that the scale removing medium supplied to the second wheel is driven by the rotation of the second wheel toward a second area extending across the first surface of the length of sheet metal;

rotating the first and second wheels in opposite directions;

positioning the first and second wheels relative to the length of sheet metal, wherein the first region is spaced from the second region along the length of sheet metal;

positioning the first and second wheels along the vicinity of opposite side edges defining the width of the length of sheet metal with the length of sheet metal centered between the first and second wheels; and

wherein substantially all of the scale is removed from the first surface of the length of sheet metal.

8. The method of claim 7, further comprising:

moving the length of sheet metal in an axial direction through the scale removing medium driven by the first and second wheels to remove scale from and clean the length of sheet metal.

9. The method of claim 7, further comprising:

adjustably positioning the first and second wheels away from or adjacent the length of sheet metal to adjust the surface finish of the length of sheet metal.

10. The method of claim 7, further comprising:

the first and second wheels are combined with a sheet metal scrubbing device and the scrubbing device is used to completely descale the length of sheet metal and adjust the surface texture of the length of sheet metal.

11. The method of claim 7, further comprising:

the first and second wheels are combined with a sheet metal scrubbing apparatus and the length of sheet metal is completely descaled and the surface texture of the length of sheet metal is adjusted by using different slurries in the first and second wheels and using the scrubbing apparatus.

12. The method of claim 7, further comprising:

combining the first and second wheels with a sheet metal scrubbing device, selectively removing a scale layer from the length of sheet metal material and adjusting the surface texture of the length of sheet metal material by selectively employing different combinations of the first and second wheels and the scrubbing device.

13. The method of claim 12, further comprising:

and only one surface of the section of metal plate is brushed by adopting the brushing device, and slurry is driven to the opposite surface of the one surface of the section of metal plate by adopting the first wheel and the second wheel.

14. The method of claim 12, further comprising:

and adopting the brushing device to brush the two opposite surfaces of the section of the metal plate, and adopting the first wheel and the second wheel to drive slurry to only one surface of the section of the metal plate.

15. The method of claim 7, further comprising:

reversing a direction of movement of the length of sheet metal passing through the apparatus to provide a range of surface finishes on the length of sheet metal.

16. The method of claim 7, further comprising:

the first and second wheels are coupled to a sheet metal scrubbing device and at least one sheet metal leveler.

17. The method of claim 7, further comprising:

adjusting rotation of the first and second wheels to change the surface roughness of the length of sheet metal.

18. The method of claim 7, further comprising:

combining the first and second wheels on one face of the length of sheet metal with the third and fourth wheels on the opposite face of the length of sheet metal to create a rough surface on the one face of the length of sheet metal and a smooth surface on the opposite face of the length of sheet metal.

19. The method of claim 7, further comprising:

combining the first and second wheels with a rotating brush and reducing surface roughness and selectively removing a scale layer from the length of sheet metal by using the brush.

20. An apparatus for removing scale from sheet metal comprising:

a descaler for receiving a length of sheet metal, the sheet metal having a width transverse to a length of the sheet metal, the descaler operable to descale the top and bottom surfaces of the length of sheet metal across an entire width of the length of sheet metal as the length of sheet metal passes through the descaler;

a descaler liquid slurry supply mechanism which is communicated with the descaler and supplies liquid slurry to the descaler, and withdraws and circulates the liquid slurry supplied to the descaler;

a first rotating impeller having a rotating shaft, the first rotating impeller being positioned on the descaler to receive the slurry provided by the liquid slurry supply mechanism and to centrifugally drive the slurry toward an impact area across the width of the sheet metal in the top surface of the length of sheet metal as the length of sheet metal passes through the descaler;

a second rotating impeller having a different rotational axis than the rotational axis of the first rotating impeller, the second rotating impeller being positioned on the descaler to receive the slurry provided by the liquid slurry supply mechanism and to centrifugally drive the slurry toward an impact region across the width of the sheet metal in the top surface of the length of sheet metal as the length of sheet metal passes through the descaler;

a third rotating impeller having a rotating shaft, the third rotating impeller being positioned on the descaler to receive the slurry provided by the liquid slurry supply mechanism and to centrifugally drive the slurry toward an impact area across the width of the sheet metal in the bottom surface of the length of sheet metal as the length of sheet metal passes through the descaler;

a fourth rotating impeller having a different rotational axis than the rotational axis of the third rotating impeller, the fourth rotating impeller being positioned on the descaler to receive the slurry provided by the liquid slurry supply mechanism and to centrifugally drive the slurry toward an impact region across the width of the sheet metal in the bottom surface of the length of sheet metal as the length of sheet metal passes through the descaler;

wherein the first and second rotating impellers are positioned as symmetrical mirror images across the width of the length of sheet metal top surface to centrifugally drive the slurry across the width of the sheet metal toward the top surface of the length of sheet metal in the shape of a symmetrical mirror image of the slurry being driven;

wherein the third and fourth rotating impellers are positioned as symmetrical mirror images across the width of the length of sheet metal bottom surface to centrifugally drive the slurry across the width of the sheet metal toward the bottom surface of the length of sheet metal in the shape of a symmetrical mirror image of the slurry being driven;

wherein the second rotating impeller is spaced from the first rotating impeller along the length of the sheet metal a sufficient distance such that scale removing medium driven from the second rotating impeller does not substantially interfere with scale removing medium driven by the first rotating impeller;

wherein the first and second rotating impellers are positioned adjacent opposite side edges defining a width of the length of sheet metal, and the length of sheet metal is centered between the first and second rotating impellers;

wherein the third rotary impeller is spaced from the fourth rotary impeller along the length of the sheet metal a sufficient distance such that scale removing medium driven from the third rotary impeller does not substantially interfere with scale removing medium driven from the fourth rotary impeller;

wherein the third and fourth rotating impellers are positioned adjacent opposite side edges defining a width of the length of sheet metal centered between the third and fourth rotating impellers; and

wherein substantially all of the scale is removed from the top and bottom surfaces of the sheet metal.

21. The apparatus of claim 20, further comprising:

at least one of the first, second, third and fourth rotating impellers is movable towards and away from the respective surface of the length of sheet metal to adjust the impact strength and impact area.

22. The apparatus of claim 20, further comprising:

the descaler is included as part of a sheet metal processing line that includes a brushing apparatus for further removing scale from the length of sheet metal, removing slurry debris from the length of sheet metal, and adjusting the surface texture of the length of sheet metal.

23. The apparatus of claim 20, further comprising:

the descaler is used as a part of a sheet metal processing line, and the line comprises a sheet metal rolling device and a sheet metal coating device.

24. The apparatus of claim 20, further comprising:

the first and second pairs of rotating impellers are disposed on opposite sides of the length of sheet metal and create slurry impingement areas on aligned opposite surfaces of the length of sheet metal to minimize deflection of the length of sheet metal.

25. A method for slurry bombardment of metal comprising:

positioning a first impeller having a first axis of rotation adjacent a first surface of a metal object;

positioning a second impeller having a second axis of rotation adjacent to the first surface of the metal object, the second axis of rotation being different from the first axis of rotation;

supplying slurry to the first and second impellers; and

rotating the first and second impellers about the respective first and second axes of rotation, whereby slurry supplied to the first and second impellers is driven towards a first region and a second region, respectively, of a first surface of the metal object by rotating the first and second impellers;

positioning a third impeller having a third axis of rotation proximate a second surface of the metal object opposite the first surface of the metal object;

positioning a fourth impeller having a fourth axis of rotation adjacent to the second surface of the metal object, the fourth axis of rotation being different from the third axis of rotation;

feeding the third and fourth impellers with the slurry;

rotating the third and fourth impellers about the respective third and fourth axes of rotation, thereby driving the slurry supplied to the third and fourth impellers towards third and fourth regions, respectively, of the second surface of the metal object by rotating the third and fourth impellers;

wherein the first and second impellers are positioned such that the first and second regions are symmetrical mirror images across the width of the metal object, and the third and fourth impellers are positioned such that the third and fourth regions are symmetrical mirror images across the width of the metal object;

wherein the second impeller is spaced from the first impeller along the length of the first surface of the metal object a sufficient distance such that scale removing medium driven from the second impeller does not substantially interfere with scale removing medium driven from the first impeller;

wherein the first and second impellers are positioned adjacent opposite side edges defining a width of the metal object with the metal object centered between the first and second impellers;

wherein the third impeller is spaced from the fourth impeller along the length of the metal object a sufficient distance such that scale removing medium driven from the third impeller does not substantially interfere with scale removing medium driven from the fourth impeller;

wherein the third and fourth impellers are positioned adjacent to opposite side edges defining a width of the metal object, and the metal object is centered between the third and fourth impellers; and

wherein substantially all of the scale is removed from the first and second surfaces of the metal object.

26. The method of claim 25, further comprising:

adjusting rotation of the first and second impellers to change a surface roughness of the first surface of the metal object.

27. The method of claim 25, further comprising:

creating a rough surface on the first surface of the metal object by the slurry driven towards the first surface and creating a smooth surface on the second surface of the metal object by the slurry driven towards the second surface.

28. The method of claim 25, further comprising:

the first and second impellers are combined with a rotating brush that is employed to reduce the roughness of the surface and to selectively remove scale layers from the metal object.

29. The method of claim 25, further comprising:

positioning a brusher adjacent a second surface of the metal object opposite the first surface; and the number of the first and second groups,

and brushing the second surface of the metal object by a brushing machine.