Here is the actual patent, be warned its long...........
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United States Patent 6,270,394
Visaisouk , et al. August 7, 2001
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Apparatus and method for continuous ice blasting
Abstract
The invention provides an apparatus and method for continuously delivering ice particulates at high velocity onto a substrate for treating the surface of the substrate. The apparatus includes a refrigerated curved surface that is brought into contact with water to form a thin, substantially uniform, ice sheet on the surface. This ice sheet is of such thickness as to contain stresses so that the sheet is predisposed to fracture into particulates. A doctor-knife is mounted to intercept a leading edge of the ice sheet and to fragment the ice sheet to produce ice particulates. These ice particulates enter into at least one ice-receiving tube that extends substantially along the length of the doctor-knife. Once in the tube, the ice particulates are fluidized by a constant flow of air and are carried into a hose for delivery through an ice-blasting nozzle under pressure. The flow path for the ice particulates in the tube and the delivery hose has a substantially constant cross-sectional area, and flow surfaces are smooth to minimize the likelihood of blockages. Advantageously, the apparatus is able to function for extended periods of time without ice blockages occurring.
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Inventors: Visaisouk; Sam (Mercer Island, WA); Fisher; Norman W. (Bellevue, WA)
Assignee: Universal Ice Blast, Inc. (Kirkland, WA)
Appl. No.: 465211
Filed: December 14, 1999
Current U.S. Class: 451/39; 62/346; 62/354; 222/146.6; 241/DIG17; 451/53; 451/60; 451/99; 451/446
Intern'l Class: B24B 001/00; B24C 001/00
Field of Search: 451/38,39,53,60,99 62/345,346,354 134/6,7 222/146.6 241/DIG. 17
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References Cited [Referenced By]
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U.S. Patent Documents
2549215 Apr., 1951 Mansted.
2699403 Jan., 1955 Courts.
2749722 Jun., 1956 Knowles.
2758451 Aug., 1956 Lauterbach.
2860490 Nov., 1958 Taylor.
3403532 Oct., 1968 Knowles.
4389820 Jun., 1983 Fong.
4512160 Apr., 1985 Mas.
4538428 Sep., 1985 Wilkerson.
4617064 Oct., 1986 Moore.
4703590 Nov., 1987 Westergaard.
4744181 May., 1988 Moore et al.
4965968 Oct., 1990 Kelsall.
5196034 Mar., 1993 Ono et al.
5203794 Apr., 1993 Stratford et al.
5249426 Oct., 1993 Spivak et al.
5448894 Sep., 1995 Niblock et al.
5520572 May., 1996 Opel et al.
5623831 Apr., 1997 Mesher et al.
Foreign Patent Documents
1321748 Aug., 1993 CA.
4115142 Nov., 1992 DE.
94/14572 Jul., 1994 WO.
94/16861 Aug., 1994 WO.
96/35913 Nov., 1996 WO.
Other References
GM Investigates Ice-Impact Technology, p. 2, Metalworking, Jul. 7, 1993.
Brochure: MAJA Fine Ice Producing Units, SA 50 E--SA 6000 TL, MAJA Equipment Co. Inc, undated.
Brochure: A-1 Flake Ice Machines, A-1 Refrigeration Co., undated.
"Ice Blast! The Most Effective Deburring and Degreasing System Available," Brochure, Ice Blast.RTM. International, Inc.
Primary Examiner: Eley; Timothy V.
Attorney, Agent or Firm: Christensen O'Connor Johnson Kindness PLLC
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Parent Case Text
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This application is a continuation of prior application Ser. No. 09/050,616, filed Mar. 30, 1998, which issued Dec. 14, 1999, as U.S. Pat. No. 6,001,000, which was a continuation-in-part of prior application Ser. No. 08/660,905, filed Jun. 7, 1996, which issued Jun. 22, 1999, as U.S. Pat. No. 5,913,711, priority from the filing dates of which is hereby claimed under 35 U.S.C. .sctn. 120.
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Claims
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The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A method of continuously producing a stream of ice particulates, comprising:
(a) continuously freezing water into a thin sheet of ice onto a surface of a rotating refrigerated element while controlling a thickness of the sheet, a rate of rotation of the refrigerated element and a contour defined by the sheet so that the sheet self fragments into particles upon removal from the surface;
(b) continuously harvesting the self fragmenting sheet from the surface of the refrigerated element with a knife blade to form particles;
(c) directly entraining the harvested particles into a stream of air with sufficient velocity to fluidize the particles; and
(d) continuously ejecting the particles from the nozzle.
2. The method of claim 1, further comprising partitioning the fluidized particles into a plurality of substreams and continuously ejecting the particles in the substreams through a corresponding plurality of nozzles.
3. The method of claim 2, further comprising individually controlling the plurality of nozzles.
4. The method of claim 3, wherein the velocity of the particles being discharged from the nozzles is controlled on an individual nozzle basis.
5. The method of claim 2, wherein one or more of the nozzles is operated to automatically traverse a surface of a substrate that is impinged by the particles.
6. The method of claim 2, wherein the plurality of substreams flow through a plurality of divided sections of a receiving tube, each terminating in a corresponding nozzle.
7. A method of continuously producing a stream of ice particulates comprising:
(a) continuously freezing water into a thin sheet of ice onto a surface of a rotating refrigerated element;
(b) continuously harvesting the sheet from the surface of the refrigerated element with a knife blade to form particles;
(c) directly entraining the harvested particles into at least one stream of air within at least one receiving tube with sufficient velocity to fluidize the particles;
(d) partitioning the fluidized stream of particles into a plurality of substreams; and
(e) continuously ejecting the particles in the plurality of substreams through a corresponding plurality of nozzles.
8. The method of claim 7, further comprising individually controlling the plurality of nozzles.
9. The method of claim 8, wherein the velocity of the particles being discharged from the nozzles is controlled on an individual nozzle basis.
10. The method of claim 7, wherein one or more of the nozzles is operated to automatically traverse a surface of a substrate that is impinged by the particles.
11. The method of claim 7, wherein the plurality of substreams flow through a plurality of divided sections of a receiving tube, each terminating in a corresponding nozzle.
12. An apparatus for delivering ice particulates, the apparatus comprising:
(a) a refrigerated cooling element mounted to rotate about a central axis, the refrigerated cooling element defining a contoured surface on which a thin sheet of ice is continuously frozen, the refrigerated element defining a speed of rotation and the sheet of ice defining a thickness;
(b) a refrigerant supply for supplying refrigerant to the refrigerated element to cool the contoured surface of the refrigerated element to at least 0.degree. C.;
(c) a water supply for continually introducing water to the contoured surface of the refrigerated element;
(d) a controller for controlling the speed of rotation of the refrigerated element and the thickness of the ice sheet, the contour of the surface of the refrigerated element being selected and the controller being operated so that the ice sheet formed on the surface of the refrigerated element self fragments upon removal from the surface;
(e) a knife blade mounted in close proximity to the contoured surface of the refrigerated element, and extending along a length of the surface of the refrigerated element, to continuously harvest the ice sheet from the surface of the refrigerated element to form particles;
(f) an ice receiving conduit having an inlet aperture adjacent the knife blade to continuously collect the particles as they are harvested from the surface of the refrigerated element into the inlet aperture defined by the ice receiving conduit, the ice receiving conduit being supplied by a stream of air passing through the conduit from the inlet aperture to an outlet with sufficient velocity to fluidize the particles there within; and
(g) a nozzle at the outlet of the ice receiving conduit for continuously ejecting the ice particles from the nozzle.
13. The apparatus of claim 12, wherein the ice receiving conduit is partitioned into a plurality of sections, further comprising a plurality of nozzles, each section of the conduit supplying a corresponding nozzle.
14. The apparatus of claim 13, comprising a controller for controlling the flow of particulates through the plurality of nozzles.
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Description
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FIELD OF THE INVENTION
The invention provides an apparatus and method for blasting small ice particulates onto surfaces, for cleaning, decontaminating, deburring, or smoothing the surfaces. More particularly, the invention provides ice particulates within a narrow range of size distribution supplied through an apparatus that makes these particulates and motivates them to a required velocity, without intermediate storage of the particulates.
BACKGROUND OF THE INVENTION
In recent years there has been increasing interest in the use of ice blasting techniques to treat surfaces. For certain applications, ice blasting provides significant advantages over chemical surface treatment, blasting with sand or other abrasive materials, hydro-blasting, and blasting with steam or dry ice. The technique can be used to remove loose material, blips and burrs from production metal components, such as transmission channel plates after machining, and even softer material, such as organic polymeric materials, including plastic and rubber components. Because water in either frozen or liquid form is environmentally safe, and inexpensive, ice blasting does not pose a waste disposal problem. The technique can also be used for cleaning surfaces, removing paint or stripping contaminants from a surface, without the use of chemicals, abrasive materials, high temperatures, or steam.
Because of these apparent advantages, ice blasting has generated significant commercial interest which lead to the development of a variety of technologies designed to deliver a high pressure spray containing ice particulates for performing particular surface treatment procedures. Some of these technologies are shown, for example, in U.S. Pat. Nos. 2,699,403; 4,389,820; 4,617,064; 4,703,590; 4,744,181; 4,965,968; 5,203,794; and 5,367,838. Despite all the effort devoted to ice-blasting equipment, the currently available equipment still suffers significant shortcomings that lead to job interruption and downtime for equipment maintenance. This is a particular disadvantage in using ice blasting in a continuous automated production line to treat surfaces of machined parts.
In general, in the prior art equipment, the ice particulates are mechanically sized, a process that can cause partial thawing of ice particulates so that they adhere together, producing larger particulates. As a result, there is not only a wide distribution in the size of ice particulates produced, and the velocity at which these particulates are ejected from a nozzle onto the surface to be treated, but also frequent blockages that necessitate equipment downtime for clearing the blocked area. Moreover, in the available equipment, the ice particulates are retained in storage hoppers, where they are physically at rest, while in contact with each other. This results in ice particulates cohering to form larger ice blocks that ultimately cause blockages with resultant stoppage of the ice blasting operation due to an insufficient supply of ice particulates to the blasting nozzle. In other equipment, the ice particulates flow along a path with abruptly varying cross-sectional area for flow. This frequently causes the accumulation of fine ice particulates in certain low pressure areas. This accumulation also ultimately results in blockage of the apparatus, causing the ice blasting operation to come to an unscheduled stop.
There yet exists a need for ice-blasting apparatus, and a method of ice blasting, that can be carried out continuously, with minimal risk of unscheduled stoppages due to ice blockages forming in the apparatus. Such an apparatus, and method of its operation, will allow more efficient ice-blasting operations, reducing labor costs for unscheduled stoppages, labor costs incurred in freeing the equipment of blockages, and permit more ready integration of ice blasting into an automated production line.
SUMMARY OF THE INVENTION
The invention provides an apparatus for producing ice particulates within a narrow size distribution, and delivering these ice particulates at a predetermined velocity onto a substrate, thereby treating the surface of the substrate to remove contaminants, to deburr, or to otherwise produce a smooth, clean surface. The apparatus of the invention may be operated continuously, with significantly reduced risk of blockage by accumulated ice, as compared to currently-available ice-blasting equipment.
In general, the invention provides an ice particulate-making apparatus that has a curved, refrigerated surface on which a thin ice sheet is formed, which is then fragmented into ice particulates that are fluidized and carried in a conduit of flowing air to impact onto the surface to be treated. The conduit is preferably smooth, and of substantially uniform cross-sectional area for flow, to minimize or eliminate ice particulate agglomeration and consequent clogging of the apparatus. To further reduce the risk of apparatus blockages, the invention prefers (but is not limited to use of transport air at a temperature above about 32.degree. F. This temperature minimizes the risk of valves, for example freezing after prolonged use, and is yet sufficiently low that significant ice melting does not occur while the ice is in contact with the transport air.
In accordance with one embodiment of the invention, the apparatus includes a refrigerated device with a curved surface, such as a cylindrical drum that is preferably rotatably mounted with outer surfaces adapted to form a thin layer of ice. In one embodiment, the drum is horizontally mounted in a basin of water. As the drum, that is refrigerated to a surface temperature of at least 0.degree. C., rotates in the basin, a thin curved ice sheet forms on the cylindrical outer surfaces of the drum. An ice breaking tool, such as a doctor-knife, is mounted near the side of the drum that is ice-coated, and extends along the length of the drum. The knife is oriented to intercept a leading edge of the ice sheet and fragment it into ice particulates as the drum rotates. An ice-receiving tube is located adjacent, and extends along the length of, the doctor-knife and is oriented so that a longitudinal slot in the tube is able to receive the ice particulates formed. In preferred embodiments, a vibrator device is attached to or integral with the tube to reduce the risk of ice agglomeration on the tube. One end of the tube is coupled to a hose supplying cold air, and the other end is coupled to an ice delivery hose that applies suction to the interior space of the tube. The delivery hose terminates in an ice blasting nozzle. As ice particulates enter into the ice-receiving tube, the particulates are carried by a continuously flowing stream of cold air into the delivery hose and thence into the ice-blasting nozzle. The flow conduit of the ice particulates (tube and hoses) has a substantially smooth (i.e. free of obstructions and surface irregularities) inner surface, and substantially uniform cross-sectional area for flow, thereby avoiding low velocity spots where ice particulates may settle, accumulate, and cause blockages.
In another embodiment, the refrigerated drum is sprayed with water to form the thin ice sheet. The drum may be horizontally mounted, as preferred to form a uniform thickness ice-sheet, or may be inclined at an angle. In one such embodiment of the invention, the refrigerated drum is vertically-oriented and water is sprayed onto the drum to form a thin curved ice sheet. As explained above, a doctor-knife extends along the length of the drum to fragment ice particulates from the sheet into an adjacent co-extensive ice-receiving tube.
In a further alternative embodiment of the invention, the refrigerated cylindrical surface is the interior surface of an annulus. At least one spray nozzle is mounted to direct water onto the cylindrical walls of the annulus to form a thin ice sheet. As before, a doctor-knife extending along the length of the cylindrical wall is used to fragment ice particulates of narrow size distribution from the ice sheet into a slot in an ice-receiving tube that is adjacent to and co-extensive with the knife.
In a yet further alternative embodiment of the invention, the entire apparatus for making ice particulates is enclosed in a pressurized vessel. The vessel may be maintained at a pressure in the range from about 20 to about 150 psig. Moreover, in this embodiment of the invention pressurized air, or another gas, is supplied to the apparatus to fluidize the ice particulates, and carry the ice particulates to a nozzle, or a plurality of nozzles, for blasting onto a surface.
According to the method of the invention, ice particulates may be prepared by freezing water into a thin, curved sheet of ice. This thin, curved ice sheet, already stressed as a result of the curvature, is relatively easily fragmented into ice particulates that are sized dependent on ice sheet thickness and radius of curvature. These ice particulates are drawn by suction pressure into a stream of cold, dry air that fluidizes and sweeps the particulates into a smooth surfaced flow conduit having a substantially constant cross-sectional area for flow. At a terminal end of this flow conduit the ice particulates are ejected onto a surface of a substrate through a nozzle at high velocity to perform deburring, cleaning, or other operations, depending upon the velocity of the ice particulates and air stream.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is an illustration of a worker blasting a surface with ice particulates from an ice blasting device of the invention;
FIG. 2 is a simplified schematic of the ice particulate-making equipment of the invention;
FIG. 3 is a schematic perspective view of an embodiment of an ice-blasting apparatus in accordance with the invention;
FIG. 4A is an end view of an embodiment of the invention showing details of the ice removal tool and ice-receiving tube of the invention;
FIG. 4B is an end view of an embodiment of the invention including water spray nozzles for forming an ice sheet on a cylindrical surface of a rotating refrigerated drum;
FIG. 4C is a schematic perspective view of an embodiment of the ice-receiving tube of the invention, equipped with an optional window; |
