WO2016075645A2 - A method and apparatus for removing an outer layer from an elongate body of metal - Google Patents

A method and apparatus for removing an outer layer from an elongate body of metal Download PDF

Info

Publication number
WO2016075645A2
WO2016075645A2 PCT/IB2015/058737 IB2015058737W WO2016075645A2 WO 2016075645 A2 WO2016075645 A2 WO 2016075645A2 IB 2015058737 W IB2015058737 W IB 2015058737W WO 2016075645 A2 WO2016075645 A2 WO 2016075645A2
Authority
WO
WIPO (PCT)
Prior art keywords
abrading medium
rollers
sheet metal
abrading
metal
Prior art date
Application number
PCT/IB2015/058737
Other languages
French (fr)
Other versions
WO2016075645A3 (en
Inventor
Gerhardus Janse COETZER
William Brian LEHANE
Eric Clancy LEHANE
Original Assignee
Coetzer Gerhardus Janse
Lehane William Brian
Lehane Eric Clancy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Coetzer Gerhardus Janse, Lehane William Brian, Lehane Eric Clancy filed Critical Coetzer Gerhardus Janse
Publication of WO2016075645A2 publication Critical patent/WO2016075645A2/en
Publication of WO2016075645A3 publication Critical patent/WO2016075645A3/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
    • B24C1/08—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for polishing surfaces, e.g. smoothing a surface by making use of liquid-borne abrasives
    • B24C1/086—Descaling; Removing coating films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C11/00—Selection of abrasive materials or additives for abrasive blasts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C3/00—Abrasive blasting machines or devices; Plants
    • B24C3/08—Abrasive blasting machines or devices; Plants essentially adapted for abrasive blasting of travelling stock or travelling workpieces
    • B24C3/10—Abrasive blasting machines or devices; Plants essentially adapted for abrasive blasting of travelling stock or travelling workpieces for treating external surfaces
    • B24C3/14—Apparatus using impellers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C9/00—Appurtenances of abrasive blasting machines or devices, e.g. working chambers, arrangements for handling used abrasive material
    • B24C9/003—Removing abrasive powder out of the blasting machine
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C9/00—Appurtenances of abrasive blasting machines or devices, e.g. working chambers, arrangements for handling used abrasive material
    • B24C9/006—Treatment of used abrasive material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Definitions

  • the method may include the further step of pre-cleaning the metal body by spraying under pressure the body with a pre-cleaning liquid comprising any one or more selected from the group consisting of water, steam and a cleaning agent, and any combination thereof, onto the outer surface of the body.
  • a pre-cleaning liquid comprising any one or more selected from the group consisting of water, steam and a cleaning agent, and any combination thereof, onto the outer surface of the body.
  • the temperature of the pre-cleaning liquid is elevated to a level above room temperature, further preferably 50 degrees Celsius.
  • figure 11 is a front perspective view showing internal components of the blasting chamber of the abrading unit of figure 7;
  • figure 20 is a detailed view of circle E shown in figure 18;
  • the blast wheels 54 are provided on each side of the sheet metal 26 and secured to the blasting chamber 38 as illustrated in figures 7, 8, and 27. This provides the blast wheels 54 adjacent the second and third set of rollers 52B and 52C respectively and are angled to blast the medium inwardly and towards a central location between the rollers 52A and 52B to form a first blast zone, and 52B and 52C respectively to form a second blast zone. These positions and orientations ensure that the abrading medium is blasted onto the sheet metal 26 at or towards a substantially central location in the blasting chamber 38. The abrading medium will furthermore be blasted from both sides of the sheet metal 26 and onto a specific area of the sheet metal 26 with a defined pattern which will increase the effectiveness of the scale removal.
  • the blast wheels will be angled to operatively blast the abrading medium onto the sheet metal at an angle of 10 to 15 degrees.
  • the blast impact is enhanced by this angle at which the abrasive is propelled towards the surface as shown in Figure 27 in that it allows for the abrasive to cut and slice the outer layer of the surface (scale) instead of hitting it at an angle of 90 degrees.
  • This angled blasting furthermore results in reduced compressive stresses as opposed to the high compressive stresses of peening operations. This reduced stress consequently reduces the mechanical deformation of the sheet metal and furthermore at least partially limits the incidence of warping.
  • the blast wheels will be further configured to project the abrading medium onto the surfaces of the sheet metal angled relative to the horizontal and vertical, in other words blasted from above and below the sheet metal, as well as along and against the direction of movement of the sheet metal. This ensures that the sheet metal is blasted from at least four angles. This at least partially prevents non-directional metal deformation and results in a relatively consistent surface finish profile and predictable pattern everywhere on the blasted surface.
  • Minimal use of liquid in the operation also provides better results in the abrading process in that the liquid does not provide an additional barrier upon being projected onto the surface of the metal body, even should the elongate metal body be in a horizontal position.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Cleaning In General (AREA)

Abstract

This invention relates to a blasting system, apparatus and method for removing an outer layer, including but not limited to iron oxides (mill scale), from an elongate body of metal. The invention further relates to a damp particulate abrading medium for use in such a system, apparatus and method; and a method and components for recycling said medium.

Description

A METHOD AND APPARATUS FOR REMOVING AN OUTER LAYER FROM AN ELONGATE BODY OF METAL
FIELD OF THE INVENTION
This invention relates to a blasting system, apparatus and method for removing an outer layer, including but not limited to iron oxides (mill scale), from an elongate body of metal. The invention further includes a damp particulate abrading medium for use in such a system, apparatus and method.
BACKGROUND TO THE INVENTION
Various processes for mechanically removing an outer layer, particularly iron oxides, (otherwise known as mill scale), from the surface of an elongate metal body, such as a horizontally orientated length of sheet metal or strip from coil, are known in the art.
These processes typically involve passing an elongate body of metal through a scale removing apparatus, sometimes known as a wheelabrator or a turbine blaster. Such a known scale removing apparatus typically includes a plurality of spaced apart rollers, being driven whilst in frictional engagement with the metal body to move the metal body horizontally past opposing blast wheels projecting scale removing medium normally consisting of dry metal abrasives manufactured from carbon steel or stainless steel onto the opposite surfaces of the metal body. The impact of the scale removing medium onto the said surfaces removes the scale from the surfaces as the metal body passes through the scale removing apparatus.
In an operationally similar process referred to as slurry blasting (or also referred to in the art as wet blasting), such as the process described in US Patent no. 7,601 ,226 (Voges), the scale removing medium usually comprises a slurry mixture of liquid and solid particles. The liquid typically includes any one or more of water, a corrosion inhibitor and a cleaning agent. The solid particles typically include known metal abrasives such as those made from stainless or carbon steel. Blasting dry abrasives with air under pressure as propellant of the abrasive has also been traditionally a means to remove scale from metal surfaces and could use metal, slag, garnet, sand or glass as abrasive agents but expressly without the addition of any liquid. This process is stationary and normally excludes the use of conveying rollers as it is a manual process usually aimed at larger bodies of manufactured metal assemblies that cannot be transported continuously on conveying rollers.
The known processes and apparatus however have a number of associated disadvantages.
A disadvantage of known processes in terms of slurry or wet blasting is the requirement of relatively high energy input with associated high costs in respect of pumping the scale removing medium which is provided in a slurry form that consists of high volumes of water to the blast wheels. These operations require the provision and constant operation of a pump, such as a positive displacement pump, to actively pump the slurry to the blast wheels.
Furthermore, in use, when the rotating blast wheels are fed with scale removing medium in the form of high liquid volume content slurry, the wheels propel a relatively large volume of liquid as opposed to solids onto the surface from which the scale is to be removed. This reduces the available energy left in the blast wheel to propel onto the surface the solid abrasive particles that actually perform the scale removal and which constitutes only a relatively small part of the total volume of the slurry. This diminishes the efficiency of blasting, slows the scale removal process down and increases the energy required of operating the blast wheels with resulting cost increase.
With slurry blasting, a spout is used to distribute the slurry inclusive of the small percentage of solid abrasives suspended therein onto the individual rotating blade of the blast wheel. This way of operation results in the lack of a timed injection of the solids onto the rotating blade. It floods the operative parts of the blast wheel with slurry and makes the achievement of a defined abrasive distribution pattern onto the surface being blasted impossible, thus diminishing efficiency and scale removal speed whilst increasing wear on the entire blast wheel and the surrounding blast cabinet resulting in high frequency of replacement and thus high maintenance costs and frequent down times.
Another disadvantage of the scale removing medium used in wet or slurry blasting operations is that it is provided in a slurry form during blasting and thus dispenses high volumes of liquid onto the surface being blasted. This results in the building up of a masking layer on the surfaces of the sheet metal (or at least an upper surface in the case where the sheet is blasted in horizontal orientation) which the solid abrasive media must penetrate in order to remove the scale. This masking layer further diminishes the efficiency of the blasting and scale removing process. This layer includes the spent slurry liquid, fine particulate scale and solid content of the scale removing medium. This is undesirable because it remains stationary on the upper surface and shields the surface against the sequential impact of the scale removing medium from the next set of blast wheels, resulting in inefficient removal of scale from the surface. Furthermore, in an attempt to alleviate this undesired condition, high volumes of liquid must be pumped onto the upper surface to remove these masking or shielding material whilst blasting in order to improve efficiency. This raises the energy, water and chemical consumption of the process resulting in higher energy cost and slows down the rate of removing the scale increasing the running costs of the slurry blasting apparatus.
A further disadvantage in wet or slurry blasting operations is that due to the fact that the blast wheels rotate in and propel large quantities of liquids as opposed to solids, the chemicals, such as corrosion-inhibitors, or detergents that are used in combination with water easily cause excessive and system operation limiting foam.
Excessive foaming furthermore leads to the unnecessary down-time of the apparatus and associated costs thereof because the foaming necessitates intermittent cleaning and maintenance of the apparatus. A further disadvantage of wet or slurry blasting operations is that the slurry consists mainly of liquid which inhibits the effectiveness of the direct contact of the suspended solid abrasive particles in the slurry on impact with the surfaces of the elongate metal body being blasted, in this instance the abrasive solids are in suspension with the liquid. When the slurry is projected against the metal body the liquid therefore, in most instances, contacts the metal body first before the abrasive solid particles in the slurry. This contributes to decreased effectiveness of the operation.
Another disadvantage includes the requirement of a dryer to dry the surfaces of the sheet metal emanating from the apparatus. This increases the installation, energy, maintenance and operational costs.
The disadvantages of a layer build-up, the requirement for drying and/or the operation of stationary shielding elements removal processes are furthermore aggravated by the elongate body of metal being operated in the scale removing apparatus with the plane of the metal body extending in a substantially horizontal orientation.
A major disadvantage of dry blasting is that it leads to unwanted dust pollution in the area of operation and that it suffers from the build up of a dust layer on the surfaces being blasted that contain non-visible chemical contaminants like soluble salts containing chlorides and/or sulphates. These render the surface in many cases unsuitable for applying paint directly onto that contaminated surface without further and secondary cleaning. Furthermore, energy and maintenance costs increase due to the obligatory operation and installation of a dust collection system. Consequential disposing of the collected dust in an environmentally friendly way increases the running cost of dry blasting systems.
Furthermore, the mechanical impact of the metal abrasive removes the scale from the steel and creates an activated exposed surface which is relatively very difficult if not impossible to be passivated during the same process. This surface remains highly reactive and will tend to corrode very soon after blasting. This is aggravated severely if the surface of the steel had been corroded in any way prior to blasting.
Surfaces contaminated with any oily substance are not suitable for dry blasting as the abrasive becomes contaminated with the oily substance on impact and if reused will disperse the oil onto further surfaces being blasted. In extreme cases the oil causes the abrasive to clog and coagulate which may damage the scale removing apparatus or render it inefficient. The oil that is so dispersed and left on the surface deters future coatings from adhering to the metal surface and results in a surface that has to be cleaned in a secondary process. This further adds to the cost of the process.
Another disadvantage of all of the known processes includes the occurrence of warping or bending of the metal surface, in particular where the sheet metal is fairly thin. This negatively affects the flatness of the sheet metal and leads to an undesired or unsuitable product that is unusable for many downstream manufacturing processes like laser cutting for example. The costs of replacing elongate metal parts bent and thus damaged by or during the blasting process or by the scale removal apparatus exceeds the value added by removing the scale therefrom by at least ten times.
OBJECT OF THE INVENTION It is an object of the present invention to provide a blasting system, apparatus and method for removing an outer layer, including but not limited to iron oxides (mill scale), from an elongate body of metal and a damp particulate abrading medium for use in such a system, apparatus and method with which the above disadvantages could at least partially be overcome or alleviated and/or to provide a more useful alternative to the known apparatus and method.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a method of removing an outer layer from an elongate body of metal, the method including the steps of: providing a supply of abrading medium;
- feeding the abrading medium to at least one centrifugal blast wheel; and projecting the abrading medium onto an outer surface of the body, the method being characterised in that the abrading medium comprises a plurality of gravity settled damp solid particles.
The method may be further characterised in that the solid particles are gravity settled in a liquid selected from the group consisting of water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof. The alkaline cleaning agent may be a low foaming non-silicated alkaline cleaning agent including amines and surfactants.
Further according to the invention, the step of feeding the abrading medium to the centrifugal blast wheel includes the step of gravity feeding said abrading medium without the use of a positive displacement pump.
Further according to the invention, the step of providing the abrading medium includes the steps of:
- providing a settlement tank to which the solid particles suspended in a carrier liquid is fed; and
- allowing the bulk of the solid particles to settle out of suspension into the bottom of the tank. Further according to the invention, the step of feeding the abrading medium to the wheel includes the step of providing at least one outlet passage at the bottom of the tank and allowing the already gravity settled damp solid particles constituting the abrading medium to move under gravity from the bottom of the tank to the wheel. The solid particles may be in the form of any ferrous or non-ferrous abrasive of which the density is at least three times that of water. Preferably the solid particles may be of a metal selected from the group consisting of stainless steel and carbon steel and a combination thereof. Further according to the invention the carrier liquid includes any one or more liquids selected from the group consisting of water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof. The alkaline cleaning agent may be a low foaming non-silicated alkaline cleaning agent including amines and surfactants. Yet further according to the invention the step of projecting the abrading medium onto an outer surface of the body includes the step of projecting said medium onto the outer surface of the body at an angle relative to the body, preferably angled relative to the longitudinal and transverse axes of the body; and at an angle of 10 to 15 degrees. The method may include the further step of pre-cleaning the metal body by spraying under pressure the body with a pre-cleaning liquid comprising any one or more selected from the group consisting of water, steam and a cleaning agent, and any combination thereof, onto the outer surface of the body. Preferably the temperature of the pre-cleaning liquid is elevated to a level above room temperature, further preferably 50 degrees Celsius.
The cleaning agent includes any one or more liquids selected from the group consisting of water, alkaline cleaning agent, detergent, surfactants, amines, de- foaming agents and mixtures thereof. The alkaline cleaning agent may be a low foaming non-silicated alkaline cleaning agent including amines and surfactants.
The method may include the further step of washing the abraded surface by rinsing under pressure, cleaning and treating the surface with a liquid comprising any one or more selected from the group consisting of water, and/or steam and a cleaning agent. The liquid includes any one or more liquids selected from the group consisting of water, alkaline cleaning agent, detergent, surfactants, amines, and a mixture thereof. The alkaline cleaning agent may be a low foaming non-silicated alkaline cleaning agent including amines and surfactants.
The method may include the further optional step of applying a film onto the abraded, rinsed, cleaned and treated outer surface of the metal body. The film may be provided as a relatively long term corrosion-inhibitor including amine additives. The corrosion-inhibitor may be pre-heated to between about 40 to 70 degrees Celsius.
According to a second aspect of the invention there is provided an abrading medium for removing an outer layer from an elongate body of metal, the medium being characterised in that the medium comprises a plurality of gravity settled damp solid particles.
The solid particles may be selected from the group consisting of any ferrous or non- ferrous abrasive of which the density is at least three times that of water and a mixture thereof. Preferably the solid particles may be of a metal selected from the group consisting of stainless steel and carbon steel. Further according to the invention the outer surface of the solid particles is cleaned, rinsed and passivated by being gravity settled through a liquid selected from the group consisting of any one or more of the following water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof. The alkaline cleaning agent may be a low foaming non-siiicated alkaline cleaning agent including amines and surfactants.
According to a third aspect of the invention there is provided a method of removing an outer layer from an elongate body of sheet metal including the steps of:
orientating the elongate body of sheet metal longitudinally and with the plane of the sheet metal arranged in an orientation of from 0 to 9 degrees relative to the vertical;
- tensioning at least part of the body of sheet metal in order to inhibit deformation of the sheet; and
projecting an abrading medium onto at least one surface of the body of sheet metal whilst in tension.
The step of tensioning at least part of the body of sheet metal may include the steps of providing at least two sets of spaced apart rollers, the rollers of each set being biased towards one another in order to frictionally engage the body of sheet metal between them; and rotating the respective sets of rollers at different relative speeds with a leading set of rollers rotating at a relatively higher speed than a lagging set of rollers such as to apply tension to the part of the body of sheet metal located between the respective sets of rollers.
Further according to the invention, the leading set of rollers comprises a first and second set of rollers. The first and second set of rollers may be driven at 100% and 98% of a predetermined speed respectively while the lagging set of rollers may be driven at 96% of the predetermined speed.
Yet further according to the invention the step of projecting an abrading medium onto at least one surface of the body of sheet metal includes projecting the abrading meaium onto said body at an angle relative to the longitudinal and transverse axes of the body; and at an angle of from 10 to 15 degrees. The abrading medium may be projected onto the surfaces of the body both along and against the general direction of movement of the body. The step of projecting the abrading medium onto the body of sheet metal include the further step of projecting the abrading medium onto opposite surfaces at or towards a central location by means of at least two sets of opposing blast wheels, the central location correlating to a position on the surface disposed between the set of blast wheels on each side.
According to a fourth aspect of the invention there is provided an apparatus for removing an outer layer from an elongate body of sheet metal including:
- a leading and a lagging set of elongate rollers wherein the rollers of each set are biased towards one another in order to frictionally engage the body of sheet metal between them to operatively drive the elongate body of sheet metal along the apparatus and wherein the elongate body of sheet metal is orientated longitudinally and with the plane of the sheet metal arranged in an orientation of from 0 to 9 degrees relative to the vertical; and
- a centrifugal blast wheel for projecting an abrasive or abrading medium onto at least one surface of the sheet metal,
characterised in that the leading set of rollers are rotatable at a relatively higher speed than the lagging set of rollers such as to apply tension to the part of the body of sheet metal disposed between the leading and lagging sets of rollers. Further according to the invention, the leading set of rollers comprises a first and second set of rollers to define a first blast zone between the second set of rollers and the lagging set of rollers, and a second blast zone defined between the first and second set of rollers. The first and second set of rollers may be driven at 100% and 98% of a predetermined speed respectively while the lagging set of rollers may be driven at 96% of the predetermined speed.
Further according to the invention the blast wheel comprise a plurality of blast wheels configured to project the abrading medium onto the surface of the body at an angle relative to the longitudinal and transverse axes of the body; and at an angle of 10 to 15 degrees. The abrading medium may be projected onto the surfaces of the body both along and against the general direction of movement of the body. The invention yet further provides for the blast wheels to be provided as two sets of blast wheels configured to project the abrading medium onto opposite surfaces at or towards a central location, the central location correlating to a position on the surface disposed between the set of blast wheels on each side.
According to a fifth aspect of the invention there is provided an apparatus for removing an outer layer from an elongate body of metal comprising:
a pre-cleaning chamber for cleaning an outer surface of the metal by removing loose solids and oils by projecting a cleaning liquid onto the surface;
a blasting chamber provided with a device for propelling abrading medium onto at least one surface of the body of metal to blast the said outer surface;
a washing chamber for removing any loose solids, metallic fines, salts consisting of chlorides and sulphates from the blasted surface; and an auger conveyor disposed proximate the floor of the pre-cleaning and washing chambers configured to operatively dispose the spent solids, metallic fines, salts and removed loose scale from the cleaning and washing chambers, the auger being provided with an elongate internal axial passage having a liquid inlet and a plurality of outlet nozzles arranged radially along the length of the auger conveyor.
The blasting chamber may further include a shaft having a liquid inlet and a plurality of outlet nozzles arranged radially along the length of the shaft. Further according to the invention the shaft to be integral with the axial passages of the auger conveyor in the pre-cleaning and washing chambers.
The blasting chamber may further include a receptacle for receiving the used abrading medium, removed scale and also the spent liquids from the pre-cleaning and washing chambers. The receptacle may include an outlet passage through which the liquids, removed scale and the used abrading medium is moved under gravity and fed by venturi into a continuously pumped carrier liquid in a pipeline connecting the clean part of a filtration unit and the inlet of a settlement tank. The apparatus may further include a protective film application chamber for operatively applying a protective film to the body of metal.
According to a sixth aspect of the invention there is provided an abrading medium settlement tank for use in an apparatus to remove an outer surface of an elongate metal body, the apparatus having a blasting chamber and a blast wheel for projecting abrading medium onto the said surface, the settlement tank being configured to receive spent solid particles suspended in a carrier liquid; the tank having at least one outlet passage at the bottom of the tank to allow gravity settled, rinsed and passivated damp solid particles constituting the abrading medium to move under gravity from the bottom of the tank to the blast wheel.
The outlet passage may include an adjustable flow valve to regulate the flow of abrading medium to the blast wheel. The settlement tank may incorporate an overflow weir and at least one further dispensing outlet disposed proximate the operative top of the tank through which the carrier, cleaning and washing liquid, unwanted removed scale and other relatively smaller and lighter solid particles are dispensed. The dispensing outlet may be in fluid communication with a filtration unit.
The invention further provides for the settlement tank to be divided in two operative bottom compartments each having two outlet passages. According to a seventh aspect of the invention there is provided a method for recycling an abrading medium emanating from apparatus for removing an outer layer from an elongate metal body, the apparatus having a blast wheel for projecting abrading medium onto the said surface, the method including the steps of: transporting spent abrading medium and discharged pre-cleaning and washing liquids to a settlement tank disposed in a position elevated relative to the blast wheel;
allowing the bulk of the larger solid particles to settle out of suspension by gravity into the bottom of the settlement tank thus forming damp, rinsed, cleaned and passivated solid particles constituting the abrading medium; and
- feeding the damp solid particles constituting the abrading medium to the blast wheel without the use of a positive displacement pump.
The invention further provides the further steps of transporting by gravity the overflow of carrier, pre-cleaning and washing liquid separated from the relatively larger solid particles that settled into the bottom of the settlement tank to a filtration unit; and filtering relatively lighter solid particles still in suspension from the liquid through a magnetic separator and/or a filter; and transporting the filtered liquid back through a storage tank to the apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described further by way of a non-limiting example with reference to the accompanying drawings wherein: figure 1 : illustrates a diagrammatic flow diagram of the pathway of elongate metal bodies and the recycling of waste material according to an aspect of the invention;
figure 2: shows a front perspective view of a blasting system for removing an outer layer from elongate bodies of metal according to a preferred embodiment of the invention;
fi igure 3: illustrates a detailed perspective view of square A of figure 2; fi igure 4: is a rear perspective view of the blasting system of figure 2; fi igure 5: illustrates a detailed perspective view of square B of figure 4; fi igure 6: is a plan view of the blasting system of figure 2;
fi igure 7: is a front perspective view of the abrading unit of the system of figure 2; figure 8: is a rear perspective view of the abrading unit of the system of figure 7;
figure 9: is a front perspective view showing internal components of a pre-cleaning chamber of figure 7;
figure 10: is a perspective rear view showing internal components of the pre-cleaning chamber of figure 9;
figure 11 : is a front perspective view showing internal components of the blasting chamber of the abrading unit of figure 7;
figure 12: is a perspective rear view of the blasting chamber of figure 1 1 showing internal components;
figure 13: shows a perspective view of a centrifugal blast wheel of the abrading unit of figure 7;
figure 14: is a front perspective view showing internal components of a washing chamber and a protective film application chamber of the abrading unit of figure 7;
figure 15: is a perspective rear view showing internal components of the washing and protective film application chambers of figure 14; figure 16: is a perspective rear view showing internal components of the washing and protective film application chambers of figure 14; figure 17 is a detailed view of circle C shown in figure 16;
figure 18: is a front perspective view showing internal components of the washing and protective film application chambers of figure 14; figure 19 is a detailed view of circle D shown in figure 18;
figure 20 is a detailed view of circle E shown in figure 18;
figure 21 is an end view of a settlement tank of the blasting system of figure 2;
figure 22: shows a perspective view of a filtration unit of the blasting system of figure 2;
figure 23 illustrates a plan view of the filtration unit of figure 22;
figure 24 is a side view of the filtration unit of figure 22;
figure 25 is a front end view of the filtration unit of figure 22;
figure 26 shows a sectioned view along the lines A-A of figure 25; and figure 27 shows a plan view of the blasting chamber with blast wheel patterns and vertical roller set directions. DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
As shown in the accompanying drawings, a blasting system according to a preferred embodiment of the invention is generally designated by reference numeral 10. The blasting system 10 comprises five main components namely an inlet conveyor assembly 12; an abrading unit 14; filtration unit 16; a settlement tank 18 and an outlet conveyor assembly 20.
Figure 1 illustrates a diagrammatic flow diagram of the system and method according to the invention. As shown, the elongate metal bodies are driven on its pathway from the inlet conveyor assembly 12 through the abrading unit 14, where it is treated accordingly, and to the outlet conveyor assembly 20.
The abrading unit 14 comprises four chambers namely a pre-cleaning chamber 36, the blasting chamber 38, a washing chamber 40 and a protective film application chamber 42.
All waste material comprising solids and liquids of the first three chambers is moved towards and gravity fed into a receptacle 64 underneath the blasting chamber 38 of the abrading unit 14. From the receptacle 64 the waste material is gravity and venturi fed into a continuously pumped carrier liquid in a pipeline connecting the clean part of the filtration unit 16 and the inlet of a settlement tank 18. From there the gravity settled damp solid particles are gravity fed back to and re-used in the blasting chamber 38 whereas the liquid containing relatively lighter, unwanted solid particles comprising the waste material is overflowed to the filtration unit 6 where it is passed through magnetic separator 74 and a filter in tank 76.
The recycled/filtered liquid is transported back for re-use in any one or more of the pre-cleaning 36, blasting 38, washing 40 and protective film application 42 chambers and is pumped as a carrier liquid into the continuously pumped pipeline between the clean part of the filtration unit 16 and settlement tank 18 passing underneath receptacle 64.
The blasting system 10 will now be described in more detail. The blasting system 10 is useful in removing an outer layer from the outer surfaces of elongate metal bodies. In particular, the system 10 provides the scale removal of iron oxides. Elongate metal bodies include various forms of steel such as profiled long metal sections like I-beams and lipped channels and metal in flat forms like sheet or plate. The system 10 is configured to provide two separate parallel extending paths for the elongate metal bodies in the direction of the arrows as illustrated in figures 2, 4 and 6, one path for receiving long and profiled metal sections and one for receiving sheet or plate metal. As seen in figures 2 to 5, the first part of the inlet conveyor assembly 12 includes a frame 22 on which a plurality of spaced apart bases 24 are hinged to receive a length of sheet metal 26. The bases 24 are each operable by a hydraulic cylinder 28 to move the bases 24 between horizontal and vertical orientations. In operation, the sheet metal 26 is placed on the bases 24 and moved to a substantially vertical orientation i.e. with the plane of the sheet metal 26 extending between 0 and 9 degrees relative to the vertical. The sheet metal 26, in the vertical orientation, are disposed on a series of spaced apart horizontal rollers 30 configured to drive the sheet metal along the inlet conveyor assembly 12 and to the abrading unit 14. The horizontal rollers 30 are chain-driven by a suitable motor (not shown). The horizontal rollers 30 are also provided along the operative path of the sheet metal 26, i.e. through the abrading unit 14 and along the length of the outlet conveyor assembly 20, to provide support and to enable the sheet metal 26 to be driven along the operative path in the substantially vertical orientation. The frame 22 also includes a vertical portion 32 which has a series of vertical rollers
34 to facilitate movement of the sheet metal 26 along the inlet conveyor assembly 12 and to the abrading unit 14 in order to maintain the sheet metal 26 in the substantially vertical orientation. In this embodiment the length and width of sheet metal that can be accommodated are as long as 13 meters in length and 2 meters in width, however the length and width, as well as the number of bases 24, can be adapted to the requirements of a particular installation.
The abrading unit 14 is divided into four subunits, namely the pre-cleaning chamber 36; blasting chamber 38; washing chamber 40 and protective film application chamber 42. Each chamber of the abrading unit 14 is provided as separate and closed chambers each having openings 44 through which the sheet metal 26 is movable. The openings 44 also include polyurethane seals 46 to isolate said chamber from adjacent chambers. The inlet conveyor assembly 12 ensures that a leading end of the sheet metal 26 is aligned with opening 44 of the abrading unit 14 configured to the width and thickness of the length of sheet metal 26. The sheet metal 26 is driven by two sets of vertical rollers 48 along the length of the pre-cleaning chamber 36. Each set of vertical rollers 48 is provided as two oppositely disposed counter- rotating rollers to receive the length of sheet metal 26 therebetween. The rollers 48 are inwardly biased and lagged with a layer of neoprene to frictionally engage and maintain sufficient friction between the rollers 48 and the sheet metal 26. In this embodiment the rollers 48 are biased by pneumatic cylinders (not shown), but it is understood that hydraulic cylinders would also be useful to provide the requisite effect. The degree of bias will be provided such that the rollers 48 form a pinch effect on the sheet metal 26 through the neoprene lagging without damaging or otherwise affecting the integrity of the sheet metal 26, but the pinch effect will be to such an extent that the sheet metal 26 is prevented from slipping and therefore driven by the rollers 48 through the pre-cleaning chamber 36. The rollers 48 are chain driven through gear motors. The bias of the rollers 48 allows metal sheets 26 of various thicknesses to be accommodated in the system 10. The thickness of the sheet metal can be up to 12mm in this embodiment but it is understood that it can be up to any other thickness in subsequent embodiments.
The pre-cleaning chamber 36 is also provided with a series of vertically orientated spray nozzles 50 disposed on opposite sides of the sheet metal 26 and directed inwardly to operatively spray anyone one or more liquids selected from the group consisting of water and chemicals onto the surfaces of the sheet metal 26. The chemicals may include, but are not limited to, an alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof. The alkaline cleaning agent is a low foaming non-silicated alkaline cleaning agent including amines and surfactants. The liquid may be at a temperature above room temperature and preferably above 50 degrees Celsius. The sheet metal 26 is cleaned from oil, grease and loose solids such as dirt, dust and loose rust, and prepared for the blasting operation when passing through the pre-cleaning chamber 36.
The metal surface is simultaneously exposed to the chemical effects of the alkalines and amines in the cleaning liquid on any possible oxidisation or corrosion that might have occurred on the sheet metal surface. The process of passivating such a surface starts in the cleaning chamber 36. The same liquid is also used in the blasting, washing and auger rinsing operations described below. The time of exposure of this surface to these chemical effects will thus be prolonged and optimised. Furthermore, the outer surface of the damp solid abrasive comprising the abrading medium have also been cleaned, washed and passivated with the same liquid by being gravity settled through it prior to blasting. This not only protects the metallic solid abrasive particles from corroding or coagulating themselves, but allows it to continue the passivation process in the blasting chamber 38 by being a carrier of the chemicals onto the blasted surface on impact. In these further instances the passivation process thus continues on the active and exposed blasted surface.
The sheet metal 26 is driven further along its path by the rollers 48 to the blasting chamber 38. The blasting chamber 38 is separated from the pre-cleaning chamber
36 by a shared opening and seals 46 through which the sheet metal 26 enters the blasting chamber 38.
The blasting chamber 38 is provided with three sets of rollers 52A, 52B and 52C which are chain driven by suitable motors (chains not shown). As shown in figures 1 1 , 12 and 27, these rollers are housed in casings 53 which protect the rollers from the abrading medium that is propelled onto the sheet metal 26, as discussed below. The rollers 52A, 52B, and 52C, as with rollers 48 of the pre-cleaning chamber 36, are inwardly biased to maintain sufficient friction between the rollers 52A, 52B and 52C and the sheet metal 26 and to ensure the pinch effect described above.
As shown in Figure 27, the blasting chamber 38 includes two sets of oppositely disposed and inclined centrifugal blast wheels 54 for projecting an abrasive that is in this case provided as an abrading medium consisting of a plurality of gravity settled, damp solid particles (not shown) onto the surfaces of the sheet metal 26. As shown in figure 13, the blast wheels 54 include a plurality of blades or vanes 56 which receive an abrasive or abrading medium through a feed 58 that leads the abrasive or abrading medium into a control cage and then an impeller (not shown separately) that times the injection of the abrasive onto the blade or vane. These blast wheels are generally used to propel dry abrasives but are used in this embodiment to propel the abrading medium emanating from the settlement tank. The blades 56 are driven by a motor 59 to propel the abrasive or abrading medium at high velocity onto the surface of the sheet metal 26. The impact of the abrasive or abrading medium onto the sheet metal removes the scale from the surfaces of the sheet metal as it passes through the blasting chamber 38.
The blast wheels 54 are provided on each side of the sheet metal 26 and secured to the blasting chamber 38 as illustrated in figures 7, 8, and 27. This provides the blast wheels 54 adjacent the second and third set of rollers 52B and 52C respectively and are angled to blast the medium inwardly and towards a central location between the rollers 52A and 52B to form a first blast zone, and 52B and 52C respectively to form a second blast zone. These positions and orientations ensure that the abrading medium is blasted onto the sheet metal 26 at or towards a substantially central location in the blasting chamber 38. The abrading medium will furthermore be blasted from both sides of the sheet metal 26 and onto a specific area of the sheet metal 26 with a defined pattern which will increase the effectiveness of the scale removal. This will also facilitate the collection of waste material as will be described in more detail below. The blast wheels will be angled to operatively blast the abrading medium onto the sheet metal at an angle of 10 to 15 degrees. The blast impact is enhanced by this angle at which the abrasive is propelled towards the surface as shown in Figure 27 in that it allows for the abrasive to cut and slice the outer layer of the surface (scale) instead of hitting it at an angle of 90 degrees. This angled blasting furthermore results in reduced compressive stresses as opposed to the high compressive stresses of peening operations. This reduced stress consequently reduces the mechanical deformation of the sheet metal and furthermore at least partially limits the incidence of warping. The blast wheels will be further configured to project the abrading medium onto the surfaces of the sheet metal angled relative to the horizontal and vertical, in other words blasted from above and below the sheet metal, as well as along and against the direction of movement of the sheet metal. This ensures that the sheet metal is blasted from at least four angles. This at least partially prevents non-directional metal deformation and results in a relatively consistent surface finish profile and predictable pattern everywhere on the blasted surface.
The abrading medium is provided as a plurality of gravity settled damp solid particles. The solid particles of the abrading medium may be stainless or carbon steel abrasives and may have a mean maximum diameter of from 10 micrometer to 5 millimeter. The solid particles are rinsed, cleaned and passivated by it being gravity settled through a liquid consisting of any one or more of the following water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof. The abrading medium will therefore be useful to remove scale from the surfaces of the sheet metal whilst simultaneously transferring the active passivating chemical elements onto the blasted surface on impact.
To at least partially further alleviate the problem of warping, the rollers 52A, 52B and 52C in the blasting chamber 38 are drivable at different speeds to provide for the tensioning of the sheet metal 26 as shown in Figure 27. The rollers 52A, 52B and 52C are operable at a predetermined speed. Roller 52A, which is the first or lagging roller located on the operative path in the blasting chamber 38, will be operated at a speed 96% of the speed while the second and third rollers 52B and 52C i.e. leading rollers, are driven at speeds of 98% and 100% respectively. This variable drive causes variable torque between the rollers thereby tensioning the sheet between the rollers. The tensioning of the sheet in turn prevents, or at least minimizes the incidence of warping of the sheet metal as a result of the medium being propelled against its outer surfaces.
The floor, walls and roof of the blasting chamber 38 are manufactured from Manganese steel and further lined with 10mm Manganese plates which may be further lined with 12.5mm thick abrasive resistant cast alloy tiles to reduce wear and tear of the chamber thereby increasing the lifespan thereof. Following the blasting of the sheet metal 26 in the blasting chamber 38, the leading edge of the sheet metal is further driven to the washing chamber 40 where spray nozzles 50 are also provided to spray water and/or a washing liquid provided as a non-silicated alkaline cleaning agent with an amine and a surfactant onto the sheet metal 26 to wash any remaining abrading medium, other loose solids from the scale removed, metallic fines, invisible surface contaminants in the form of salts, like chlorides and sulphates from the surfaces of the sheet metal 26 before it is driven to the protective film application chamber 42. The liquid may be at a temperature above room temperature and preferably above 50 degrees Celsius. The squeegeeing effect of the neoprene lagged double pinch rollers 48 and latent heat retained on the sheet metal 26 resulting from these steps also ensures that the sheet metal 26 is substantially dry before entering the optional protective film application chamber 42. A dryer is therefore not required in these operations with a consequent saving in installation and operational costs.
The protective film application chamber 42 is also provided with spray nozzles 50 but operatively sprays a relatively long-term corrosion-inhibitor or other appropriate coating pumped from a tank underneath this chamber onto the surfaces of the sheet metal 26. These coatings may also include amine additives which inhibits corrosion of the sheet metal 26. The corrosion inhibitors are heated to between about 40 to 70 degrees Celsius by a suitable heat element in that tank (not shown). Chambers 40 and 42 are also separated by openings and seals similar to 46 in the pre-cleaning chamber. Figures 14 and 15 also illustrate walls 51 which separate the chambers 40 and 42. It will be understood that these walls are similarly provided in the other chambers 36 and 38.
The liquid/solid mixture emanating from the first three chambers of the abrading unit i.e. water, chemicals and abrading medium, sprayed or propelled onto the outer surfaces of the sheet metal 26 are recycled as follows. As shown in Figure 18 and 19 an auger conveyor 60 is provided along the length of the floors of the pre- cleaning chamber 36 and washing chamber 40. The auger conveyor 60 has an elongate axial passage having an inlet and outlet nozzles 62 provided radially and in a helical pattern along the length of the auger which operatively spray cleaning liquid into the respective chambers as the shaft of the auger is rotated. The sprayed cleaning liquid from the rotating nozzles 62 operatively loosens and drives solid ^
particles trapped underneath the helix of the auger and simultaneously washes the roof, walls and floors of the chambers and facilitates the collection of the waste material, i.e. the spent media, on the auger conveyor 60. The liquid may be at a temperature above room temperature and preferably above 50 degrees Celsius.
The auger conveyor 60 is configured to convey the waste material into a receptacle 64 of the blasting chamber 38 where it is collected. The abrading medium blasted from the blast wheels 54 in the blasting chamber 38 collects in the receptacle 64 and no screw blade of the auger conveyor 60 is therefore provided in the blasting chamber 38, however the nozzles 62 are provided to facilitate the collection of waste material in the receptacle 64 as well as the cleaning of the walls and floors of the chamber 38. The collected waste material in the receptacle 64 is subsequently fed by gravity and venturi into outlets 66 and transported to the settlement tank 18 located above the blasting chamber 38 for further processing.
The waste material, consisting of liquid and solid particles, will be allowed to at least partially separate by gravity in the settlement tank 18. The relatively larger and heavier solid abrasive particles which settle at the bottom of the tank 18 will be sufficiently rinsed and cleaned by the detergents in the liquid component, whilst also being passivated by the alkaline and amine components of the liquid to be reused as abrading medium The relatively smaller and lighter solid particles comprise mainly spent abrasive, loose scale and rust solid particles and do not gravity settle into the bottom of the tank, but overflow from the tank in suspension with the liquid that after having overflowed, is gravity fed to the filtration unit 16. Simultaneously at the bottom of the tank 18, the abrading medium moves by gravity into the blasting chamber 38 through the blast hoses or pipes between outlets 68 and the feeds 58 of the blast wheels 54 as shown in Figures 7 and 8. The usable elements in the waste material can therefore by re-used as abrading medium as described above whilst the unwanted loose solids that would detract from the effectiveness of blasting are filtered out as soon as it becomes too small and light to be effective.
This gravitational feeding of the abrading medium results in no energy required to specifically pump the abrading medium from the settlement tank 18 to the blast wheels 54 resulting in substantial cost savings in terms of installation and operational costs. The settlement tank 18 bottom outlets are provided with adjustable flow control valves 69 to regulate the flow of abrading medium to the blast wheels 54. This allows for controlling the operational energy consumption of the blast motors by controlling the amount of abrading medium that is allowed to move into each individual wheel. The effectiveness of scale removal and energy usage can thus be balanced and overblasting avoided. Thinner flat sheet material can thus be blasted without necessarily warping or bending the sheet. It will be understood that the provision of abrading medium from the onset of the operation will be provided in a similar fashion. In this instance the solid particles will be provided in a carrier liquid and provided to the settlement tank 18. In this instance, the carrier liquid will be provided as water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof, the alkaline cleaning agent being a low foaming non-silicated alkaline cleaning agent including amines and surfactants. The bulk of the solid particles will be allowed to settle at the bottom of the tank 18 and provided to the blast wheels accordingly.
The settlement tank 18 is furthermore divided into two compartments, as shown in figures 20 and 21 , to feed the abrading medium (whether from the onset or as recycled material) to the blast wheels 54 on either side of the sheet metal 26. The solid particles are therefore provided upfront and recycled and re-used in the system 10. It will be understood that the recycled abrading medium will be substantially identical, or have substantially identical properties compared to the abrading medium described above.
The liquid waste material will at least partially separate from the solid particles and collect in the operatively top portion of the settlement tank 18. The overflow of the liquid in the tank 18 flows through outlet 70 of the settlement tank 18 to the filtration unit 16 where it is filtered as described below. As shown in figures 7, 8, 14 and 15, the settlement tank 18 includes a plurality of covers 72 to prevent the ingress of unwanted material into the settlement tank 18 and to retain the temperature of the heated liquid by minimising evaporation. Outlet 70 of the settlement tank 18 extends further to form an inlet of the filtration unit 16. The filtration unit 16 includes a magnetic separator 74 through which the liquid waste material is passed to magnetically separate any metal particles, which may have been blasted from the surfaces of the sheet metal from the liquid waste material. The metal particles are therefore substantially removed from the liquid which liquid then settles in tank 76. The liquid is further pumped from the bottom of tank 76 in pipe 78 through a filter bed in the lower part of tank 76 to clean tank 80 of the recycling unit 16 to store the cleaned liquid for further, recycled use. In this instance, the vacuum pump 77 draws water through the filter medium. The filtered liquid is pumped with a reclaim pump 79 through outlets 82 back to the settlement tank 18 by passing underneath the receptacle 64 where it draws in the waste material by venturi into the pipeline 66 and transports same into the settlement tank 18. Another pump 75 pumps clean liquid from the clean tank 80 to the pre-cleaning 36 and washing 40 chambers through pipeline 81 and into the nozzles 62 of auger 60.
The abrading unit 14 of the system 10 therefore provides for the pre-cleaning, blasting, washing and optional filming of the sheet metal before it exits the protective film application chamber 42 through opening 44 to be driven along the outlet conveyor assembly 18.
The outlet conveyor assembly 18 is similar in construction to the inlet conveyor assembly 12 in that it is also provided with the frame 22 having a series of spaced apart horizontal rollers 30 to remove and drive the sheet metal 26 from the abrading unit 14. Also similar to the inlet conveyor assembly 12, the frame 22 includes a vertical portion 32, which maintains the sheet metal in the vertical orientation as it is received from the abrading unit 14. The vertical portion 32 includes the series of vertical rollers 34 which facilitates movement of the sheet metal 26 along the outlet conveyor 18.
Once the sheet metal is driven out of the abrading unit 14 through an outlet opening 44, any one or more of the bases 24, as required, are moved by each of its associated hydraulic cylinders 28 to orientate the sheet metal from the vertical to the horizontal in order to rest on the frame 22. The cleaned and/or treated sheet metal 26 is removed from the outlet conveyor assembly 20 and transported to its desired location.
In the case where a beam such as an I-beam is to be operated, the I-beam (not shown) will be placed on a separate path on the system 10 illustrated herein as a second series of horizontal rollers 30, to be driven along to the abrading unit 14. The system 10 is therefore provided with two separate pathways configured to operate, in similar manner, sheet metal and long steel sections such as beams. Spray nozzles 50 and blast wheels 54 identical to those provided for the length of sheet metal 26 are provided in a vertical, but also a horizontal orientation in order to direct the cleaning, scale removal or filming media, as the case may be, to the surfaces of the I-beam. It will be understood that the system 10 allows for the chambers of the abrading unit
14 to be operated separately to allow for optional treatment of the elongate metal bodies. For example, the nozzles 50 of the protective film application chamber 42 may be disengaged in cases where no coating of the metal body is required. The various drives in the system 10 are variable to operate at a line speed of between 0.5 to 12 meters per minute.
In an alternative embodiment, the use of water is substituted with the use of steam. In this instance, less water input into the system is required which will result in a cost saving. Further in such instance, the filtration unit will not be required to provide as much filtration, or may not be required at all, as the overall use of liquid is reduced.
It is accordingly asserted that the disadvantages associated with known processes could at least partially be overcome or alleviated with the blasting system and method according to the invention.
Less energy input, compared to the prior art operations, is required in the current invention in that the feeding of abrading medium occurs under gravity and in the absence of a positive displacement pump. The abrading medium is provided as a damp particulate medium of solids with minimal liquid, yet each abrasive particle has been rinsed, cleaned and passivated with the water/chemical solution every time it is used or reused. This abrading medium is propelled by normal blast wheels intended for dry abrasives consisting only of solid abrasive particles and is thus highly effective when removing scale compared to the disadvantages associated with slurry blasting. In this system that uses a damp abrading medium also consisting predominantly of solids, blasting and scale removing efficiency is thus not compromised by liquid entering the wheel uncontrolled and flooding the blast wheels or the accompanying liquid shielding the mechanical impact of the solid abrasive particle.
Yet the process is free from dust and the blasted surface is washed and passivated simultaneously unlike in dry blasting systems. Furthermore, surfaces contaminated with oily substances or grease can be blasted in this process as it allows for the abrading medium to blast onto wet surfaces as the pre-cleaned surface emanating from the pre-clean chamber will naturally be.
The foaming disadvantage has also been largely solved due to the lack of liquid containing chemicals that may cause foaming going through and being propelled and thus being agitated by the blast wheels.
Minimal use of liquid in the operation also provides better results in the abrading process in that the liquid does not provide an additional barrier upon being projected onto the surface of the metal body, even should the elongate metal body be in a horizontal position.
Minimal use of liquid also means that the metal body needs no dryers to be installed in the system 10, but still overcomes to disadvantage of dust pollution in the area of operation.
The invention furthermore provides for the waste material formed in the process to be recycled and re-used in the system 10.
The vertical orientation of the sheet metal furthermore alleviates the disadvantages of a blast masking layer build up, the requirement for drying and further facilitates the recycling process as the various media will collect on the floors of the chambers as a result of gravity and, the majority of the media will collect proximate the auger conveyor 60 where it is recycled as mentioned above.
The tension drive of the rollers 52A, 52B and 52C will alleviate the disadvantage of warping of the metal surface.
The provision of angled blasting, rather than the normal peening processes of the prior art also reduces mechanical deformation and facilitates non-directional metal flow/deformation.
It will be appreciated that in terms of the invention, variations in details are possible without departing from the scope of this disclosure.

Claims

2T CLAIMS
1. A method of removing an outer layer from an elongate body of metal, the method including the steps of:
providing a supply of abrading medium;
- feeding the abrading medium to at least one centrifugal blast wheel; and
- projecting the abrading medium onto an outer surface of the body, the method being characterised in that the abrading medium comprises a plurality of gravity settled damp solid particles.
2. A method according to claim 1 wherein the solid particles are gravity settled in a liquid selected from the group consisting of water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof.
3. A method according to claim 2 wherein the alkaline cleaning agent is a low foaming non-silicated alkaline cleaning agent including amines and surfactants.
4. A method according to claim 1 , 2 or 3 wherein the step of feeding the abrading medium to the centrifugal blast wheel includes the step of gravity feeding said abrading medium without the use of a positive displacement pump.
5. A method according to any one of the preceding claims wherein the step of providing the abrading medium includes the steps of:
- providing a settlement tank to which the solid particles suspended in a carrier liquid is fed; and
- allowing the bulk of the solid particles to settle out of suspension into the bottom of the tank.
6. A method according to any one of the preceding claims wherein the step of feeding the abrading medium to the wheel includes the step of providing at least one outlet passage at the bottom of the tank and allowing the already gravity settled damp solid particles constituting the abrading medium to move under gravity from the bottom of the tank to the wheel.
7. A method according to any one of the preceding claims wherein the solid particles are in the form of any ferrous or non-ferrous abrasive of which the density is at least three times that of water.
8. A method according to claim 7 wherein the solid particles are in the form of a metal selected from the group consisting of stainless steel and carbon steel and a combination thereof.
9. A method according to any one of claims 5 to 8 wherein the carrier liquid includes any one or more liquids selected from the group consisting of water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof.
10. A method according to claim 9 wherein the alkaline cleaning agent is a low foaming non-silicated alkaline cleaning agent including amines and surfactants.
1 1 . A method according to any one of the preceding claims wherein the step of projecting the abrading medium onto an outer surface of the body includes the step of projecting said medium onto the outer surface of the body at an angle relative to the longitudinal and transverse axes of the body.
12. A method according to claim 1 1 wherein the angle is from 10 to 15 degrees.
13. A method according to any one of the preceding claims including the further step of pre-cleaning the metal body by spraying under pressure the body with a pre-cleaning liquid comprising any one or more selected from the group consisting of water, steam and a cleaning agent, and any combination thereof, onto the outer surface of the body.
14. A method according to claim 13 wherein a temperature of the pre-cleaning liquid is elevated to a level above room temperature.
15. A method according to claim 14 wherein the temperature is 50 degrees Celsius.
16. A method according to any one of claims 13 to 15 wherein the cleaning agent includes any one or more liquids selected from the group consisting of water, 23 alkaline cleaning agent, detergent, surfactants, amines, de-foaming agents and mixtures thereof,
17. A method according to claim 16 wherein the alkaline cleaning agent is a low foaming non-silicated alkaline cleaning agent including amines and surfactants.
18. A method according to any one of the preceding claims wherein the method includes the further step of washing the abraded surface by rinsing under pressure, cleaning and treating the surface with a liquid comprising any one or more selected from the group consisting of water and/or steam and a cleaning agent.
19. A method according to claim 18 wherein the liquid includes any one or more liquids selected from the group consisting of water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof.
20. A method according to claim 19 wherein the alkaline cleaning agent is a low foaming non-silicated alkaline cleaning agent including amines and surfactants.
21. A method according to any one of claims 18 to 20, as read with any one of claims 13 to 17, including the further step of applying a film onto the abraded, rinsed, cleaned and treated outer surface of the metal body.
22. A method according to claim 21 wherein the film is provided as a corrosion- inhibitor including amine additives.
23. A method according to claim 22 wherein the corrosion-inhibitor is pre-heated to between about 40 to 70 degrees Celsius.
24. An abrading medium for removing an outer layer from an elongate body of metal, the medium being characterised in that the medium comprises a plurality of gravity settled damp solid particles.
25. An abrading medium as claimed in claim 24 wherein the solid particles are selected from the group consisting of any ferrous and non-ferrous abrasive of which the density is at least three times that of water and a mixture thereof.
26. An abrading medium as claimed in claim 25 wherein the solid particles are in the form of a metal selected from the group consisting of stainless steel and carbon steel.
27. An abrading medium as claimed in any one of claims 24 to 26 wherein the outer surface of the solid particles is cleaned, rinsed and passivated by being gravity settled through a liquid selected from the group consisting of any one or more of the following water, alkaline cleaning agent, detergent, surfactants, amines, and mixtures thereof.
28. An abrading medium as claimed in claim 27 wherein the alkaline cleaning agent is a low foaming non-siltcated alkaline cleaning agent including amines and surfactants.
29. A method of removing an outer layer from an elongate body of sheet metal including the steps of:
orientating the elongate body of sheet metal longitudinally and with the plane of the sheet metal arranged in an orientation of from 0 to 9 degrees relative to the vertical;
- tensioning at least part of the body of sheet metal in order to inhibit deformation of the sheet; and
projecting an abrading medium onto at least one surface of the body of sheet metal whilst in tension.
30. A method according to claim 29 wherein the step of tensioning at least part of the body of sheet metal includes the steps of providing at least two sets of spaced apart rollers, the rollers of each set being biased towards one another in order to frictionally engage the body of sheet metal between them; and rotating the respective sets of rollers at different relative speeds with a leading set of rollers rotating at a relatively higher speed than a lagging set of rollers such as to apply tension to the part of the body of sheet metal located between the respective sets of rollers.
31. A method according to claim 30 wherein the leading set of rollers comprises a first and second set of rollers and wherein the first and second set of rollers are driven at 100% and 98% of a predetermined speed respectively while the lagging set of rollers are driven at 96% of the predetermined speed.
32. A method according to any one of claims 29 to 31 wherein the step of projecting an abrading medium onto at least one surface of the body of sheet metal includes projecting the abrading medium onto said body at an angle relative to the longitudinal and transverse axes of the body.
33. A method according to claim 32 wherein the angle is from 10 to 15 degrees.
34. A method according to any one of claims 29 to 33 wherein the step of projecting the abrading medium onto the body of sheet metal include the further step of projecting the abrading medium onto the surfaces of the body both along and against the general direction of movement of the body.
35. A method according to any one of claims 29 to 34 wherein the step of projecting the abrading medium onto the body of sheet metal include the further step of projecting the abrading medium onto opposite surfaces at or towards a central location by means of at least two sets of opposing blast wheels, the central location correlating to a position on the surface disposed between the set of blast wheels on each side.
36. A method according to any one of claims 29 to 35 wherein the abrading medium comprises a plurality of gravity settled damp solid particles.
37. An apparatus for removing an outer layer from an elongate body of sheet metal including:
- a leading and a lagging set of elongate rollers wherein the rollers of each set are biased towards one another in order to frictionally engage the body of sheet metal between them to operatively drive the elongate body of sheet metal along the apparatus and wherein the elongate body of sheet metal is orientated longitudinally and with the plane of the sheet metal arranged in an orientation of from 0 to 9 degrees relative to the vertical; and a centrifugal blast wheel for projecting an abrasive or abrading medium onto at least one surface of the sheet metal,
characterised in that the leading set of rollers are rotatable at a relatively higher speed than the lagging set of rollers such as to apply tension to the part of the body of sheet metal disposed between the leading and lagging sets of rollers.
An apparatus according to claim 37 wherein the leading set of rollers comprises a first and second set of rollers to define a first blast zone between the second set of rollers and the lagging set of rollers, and a second blast zone defined between the first and second set of rollers.
39. An apparatus according to claim 38 wherein the first and second set of rollers are operatively driven at 100% and 98% of a predetermined speed respectively while the lagging set of rollers are driven at 96% of the predetermined speed.
40. An apparatus according to any one of claims 37 to 39 wherein the blast wheel comprise a plurality of blast wheels configured to project the abrading medium onto the surface of the body at an angle relative to the longitudinal and transverse axes of the body.
41 . An apparatus according to claim 40 wherein the angle is from 10 to 15 degrees.
42. An apparatus according to claim 40 or 41 wherein the blast wheels are configured to project the abrading medium onto the surfaces of the body both along and against the general direction of movement of the body.
43. An apparatus according to any one of claims 40 to 42 wherein the blast wheels are provided as two sets of blast wheels configured to project the abrading medium onto opposite surfaces at or towards a central location, the central location correlating to a position on the surface disposed between the set of blast wheels on each side.
44. An apparatus for removing an outer layer from an elongate body of metal comprising: a pre-cleaning chamber for cleaning an outer surface of the metal by removing loose solids and oils by projecting a cleaning liquid onto the surface;
a blasting chamber provided with a device for propelling abrading medium onto at least one surface of the body of metal to blast the said outer surface;
a washing chamber for removing any loose solids, metallic fines, salts consisting of chlorides and sulphates from the blasted surface; and an auger conveyor disposed proximate the floor of the pre-cleaning and washing chambers configured to operatively dispose the spent solids, metallic fines, salts and removed loose scale from the cleaning and washing chambers, the auger being provided with an elongate internal axial passage having a liquid inlet and a plurality of outlet nozzles arranged radially along the length of the auger conveyor.
45. An apparatus according to claim 44 wherein the blasting chamber further includes a shaft having a liquid inlet and a plurality of outlet nozzles arranged radially along the length of the shaft.
46. An apparatus according to claim 45 wherein the shaft is integral with the axial passages of the auger conveyor in the pre-cleaning and washing chambers.
47. An apparatus according to any one of claims 44 to 46 wherein the blasting chamber further includes a receptacle for receiving the used abrading medium, removed scale and also the spent liquids from the pre-cleaning and washing chambers.
48. An apparatus according to claim 47 wherein the receptacle includes an outlet passage through which the liquids, removed scale and the used abrading medium is moved under gravity and fed by venturi into a continuously pumped carrier liquid in a pipeline connecting the clean part of a filtration unit and the inlet of a settlement tank.
49, An apparatus according to any one of claims 44 to 48 further including a protective film application chamber for operatively applying a protective film to the body of metal.
50. An abrading medium settlement tank for use in an apparatus to remove an outer surface of an elongate metal body, the apparatus having a blasting chamber and a blast wheel for projecting abrading medium onto the said surface, the settlement tank being configured to receive spent solid particles suspended in a carrier liquid; the tank having at least one outlet passage at the bottom of the tank to allow gravity settled, rinsed and passivated damp solid particles constituting the abrading medium to move under gravity from the bottom of the tank to the blast wheel.
51. A tank according to claim 51 wherein the outlet passage includes an adjustable flow valve to regulate the flow of abrading medium to the blast wheel.
52. A tank according to claim 50 or 51 wherein the tank includes an overflow weir and at least one further dispensing outlet disposed proximate the operative top of the tank through which the carrier, cleaning and washing liquid, unwanted removed scale and other relatively smaller and lighter solid particles are dispensed.
53. A tank according to claim 52 wherein the dispensing outlet is in fluid communication with a filtration unit.
54. A tank according to any one of claims 50 to 53 wherein the tank is divided in two operative bottom compartments each having two outlet passages.
55. A method for recycling an abrading medium emanating from apparatus for removing an outer surface of an elongate metal body, the apparatus having a blast wheel for projecting abrading medium onto the said surface, the method including the steps of:
- transporting spent abrading medium and discharged pre-cleaning and washing liquids to a settlement tank disposed in a position elevated relative to the blast wheel;
- allowing the bulk of the larger solid particles to settle out of suspension by gravity into the bottom of the settlement tank thus forming damp, rinsed, cleaned and passivated solid particles constituting the abrading medium; and
- feeding the damp solid particles constituting the abrading medium to the blast wheel without the use of a positive displacement pump.
56. A method according to claim 55 including the further steps of transporting by gravity the overflow of carrier, pre-cleaning and washing liquid separated from the relatively larger solid particles that settled into the bottom of the settlement tank to a filtration unit; and filtering relatively lighter solid particles still in suspension from the liquid through a magnetic separator and/or a filter; and transporting the filtered liquid back through a storage tank to the apparatus.
57. A method of removing an outer layer from an elongate body of sheet metal substantially as herein described with reference to the accompanying figures.
58. An abrading medium for removing an outer layer from an elongate body of metal substantially as herein described with reference to the accompanying figures.
59. An apparatus for removing an outer layer from an elongate body of metal substantially as herein described with reference to the accompanying figures.
60. An abrading medium settlement tank for use in an apparatus to remove an outer surface of an elongate metal body substantially as herein described with reference to the accompanying figures.
61. A method for recycling an abrading medium emanating from apparatus for removing an outer surface of an elongate metal body substantially as herein described with reference to the accompanying figures.
PCT/IB2015/058737 2014-11-12 2015-11-12 A method and apparatus for removing an outer layer from an elongate body of metal WO2016075645A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA2014/08306 2014-11-12
ZA201408306 2014-11-12

Publications (2)

Publication Number Publication Date
WO2016075645A2 true WO2016075645A2 (en) 2016-05-19
WO2016075645A3 WO2016075645A3 (en) 2016-07-21

Family

ID=54695806

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2015/058737 WO2016075645A2 (en) 2014-11-12 2015-11-12 A method and apparatus for removing an outer layer from an elongate body of metal

Country Status (2)

Country Link
WO (1) WO2016075645A2 (en)
ZA (4) ZA201508373B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3101005A1 (en) * 2019-09-25 2021-03-26 Alter Ego A method of treating wooden barrels using a shot-based abrasive and a treatment device for its implementation
KR102234205B1 (en) * 2020-07-20 2021-03-31 주식회사 디케이씨 Shot Blast Machine for Vertical Type Pickling
CN112677053A (en) * 2020-12-21 2021-04-20 盐城成越环保设备有限公司 High-efficiency shot blasting machine driven by electromagnetism
EP4274708A4 (en) * 2021-05-11 2024-05-22 The Mat Works Ltd Descaling cell component and method

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7601226B2 (en) 2006-09-14 2009-10-13 The Material Works, Ltd. Slurry blasting apparatus for removing scale from sheet metal

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4216405A1 (en) * 1992-05-18 1993-11-25 Henkel Kgaa Pumpable alkaline cleaner concentrates
US5637029A (en) * 1993-11-22 1997-06-10 Lehane; William B. Method and apparatus for shot blasting materials
DE10149148B4 (en) * 2000-10-11 2006-06-14 Chemetall Gmbh A method of coating metallic surfaces with an aqueous polymer-containing composition, the aqueous composition, and the use of the coated substrates
US8764513B1 (en) * 2011-01-05 2014-07-01 Richard L. Spears Media recycling apparatus and process for wet media blast operations

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7601226B2 (en) 2006-09-14 2009-10-13 The Material Works, Ltd. Slurry blasting apparatus for removing scale from sheet metal

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3101005A1 (en) * 2019-09-25 2021-03-26 Alter Ego A method of treating wooden barrels using a shot-based abrasive and a treatment device for its implementation
WO2021058147A1 (en) * 2019-09-25 2021-04-01 Alter Ego Method for treating wooden barrels using a grit-based and/or slag-based abrasive, and treatment device for implementing same
KR102234205B1 (en) * 2020-07-20 2021-03-31 주식회사 디케이씨 Shot Blast Machine for Vertical Type Pickling
CN112677053A (en) * 2020-12-21 2021-04-20 盐城成越环保设备有限公司 High-efficiency shot blasting machine driven by electromagnetism
CN112677053B (en) * 2020-12-21 2022-02-18 盐城成越环保设备有限公司 High-efficiency shot blasting machine driven by electromagnetism
EP4274708A4 (en) * 2021-05-11 2024-05-22 The Mat Works Ltd Descaling cell component and method

Also Published As

Publication number Publication date
ZA201508374B (en) 2016-12-21
ZA201508375B (en) 2017-02-22
ZA201508373B (en) 2016-12-21
WO2016075645A3 (en) 2016-07-21
ZA201508372B (en) 2016-12-21

Similar Documents

Publication Publication Date Title
US5637029A (en) Method and apparatus for shot blasting materials
EP2416926B1 (en) Method of producing rust inhibitive sheet metal through scale removal with a slurry blasting descaling cell
US8074331B2 (en) Slurry blasting apparatus for removing scale from sheet metal
WO2016075645A2 (en) A method and apparatus for removing an outer layer from an elongate body of metal
CN101516532B (en) Slurry blasting apparatus for removing scale from sheet metal
US8062095B2 (en) Method of producing rust inhibitive sheet metal through scale removal with a slurry blasting descaling cell having improved grit flow
US8764513B1 (en) Media recycling apparatus and process for wet media blast operations
US5575705A (en) Slurry blasting process
US6854169B2 (en) Method for the descaling of metal
EP2480373A1 (en) Scale removal with a slurry blasting descaling cell having improved grit flow
US3900968A (en) Mobile cleaning and polishing device
US20200406423A1 (en) Part processing and cleaning apparatus and method of same
JP6195751B2 (en) Automatic roller tilting water cleaning device for falling object receiving plate of endless belt conveyor
CN105643470A (en) Wet type steel strip acidless descaling technology and equipment of technology
KR101928700B1 (en) Shot Blast System with Continuance Belt Conveyor Type
WO2006088807A2 (en) Blast head for loosening or removing scale on a metal surface
US5259890A (en) Washing device for machine parts and method of using the device
JP3272201B2 (en) Conveyor belt surface cleaning device
JP2021123449A (en) Belt conveyor washer
US20120298138A1 (en) Process for cleaning surfaces using dry ice
JP2004130415A (en) Grinding/polishing/cleaning device
US3242618A (en) Method for surface treating articles
US3122863A (en) Scalloped edge on settling tank for grit blasting
KR101127234B1 (en) System of shot blast
KR20240005672A (en) Scale removal device and method for removing scale

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 15798247

Country of ref document: EP

Kind code of ref document: A2

DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 15798247

Country of ref document: EP

Kind code of ref document: A2

32PN Ep: public notification in the ep bulletin as address of the adressee cannot be established

Free format text: NOTING OF LOSS OF RIGHTS PURSUANT TO RULE 112(1) EPC

122 Ep: pct application non-entry in european phase

Ref document number: 15798247

Country of ref document: EP

Kind code of ref document: A2