CA2531672A1 - Jet spray tool - Google Patents

Jet spray tool Download PDF

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Publication number
CA2531672A1
CA2531672A1 CA002531672A CA2531672A CA2531672A1 CA 2531672 A1 CA2531672 A1 CA 2531672A1 CA 002531672 A CA002531672 A CA 002531672A CA 2531672 A CA2531672 A CA 2531672A CA 2531672 A1 CA2531672 A1 CA 2531672A1
Authority
CA
Canada
Prior art keywords
carbon dioxide
nozzle
supply unit
jet
spray tool
Prior art date
Legal status (The legal status 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 status listed.)
Abandoned
Application number
CA002531672A
Other languages
French (fr)
Inventor
Peter Nielsen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TECH APS AG
Original Assignee
AG TECH APS
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 AG TECH APS filed Critical AG TECH APS
Publication of CA2531672A1 publication Critical patent/CA2531672A1/en
Abandoned legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B08CLEANING
    • B08BCLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B7/00Cleaning by methods not provided for in a single other subclass or a single group in this subclass
    • B08B7/0064Cleaning by methods not provided for in a single other subclass or a single group in this subclass by temperature changes
    • B08B7/0092Cleaning by methods not provided for in a single other subclass or a single group in this subclass by temperature changes by cooling
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24CABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C1/00Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
    • B24C1/003Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods using material which dissolves or changes phase after the treatment, e.g. ice, CO2
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24CABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C5/00Devices or accessories for generating abrasive blasts
    • B24C5/02Blast guns, e.g. for generating high velocity abrasive fluid jets for cutting materials

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Nozzles (AREA)

Abstract

Jet spray tool for carbon dioxide snow comprising a jet nozzle connected to a carbon dioxide supply and comprising a precooling arrangement for precooling the jet nozzle before ejection of a jet of carbon dioxide snow from the nozzle. Preferably, the precooling arrangement comprises a intermediate chamber between the carbon dioxide supply and the nozzle and a valve between the intermediate chamber and the nozzle, where the intermediate chamber is located close to the nozzle and the intermediate chamber is configured to be filled with carbon dioxide for rapid supply of carbon dioxide gas to the nozzle upon opening of the valve.

Description

Jet spray tool FIELD OF THE INVENTION
The present invention relates to a jet spray tool for treating surfaces, especially clean-ing surfaces using a carbon dioxide snow stream.
BACKGROUND OF THE INVENTION
Carbon dioxide snow jets or jets of pellets are known as cleaning means for surfaces, for example before further surface treatment. For example, such a system is disclosed in International patent application WO 01/76778 by Nielsen.
In International patent application WO 00/74897 by Werner and Zorn, a jet spray tool with a concentric dual nozzle system is disclosed. The dual nozzle system produces a supersonic stream of support gas for the ejected carbon dioxide snow. This system is complicated and expensive to produce.
Other complicated systems are disclosed in European patent application EP 332 by Kozo et al. and Japanese patent application JP 54015623 with publication no. JP
55106538 by Yamauchi Hiroshi.
DESCRIPTION / SUMMARY OF THE INVENTION
It is the object of the invention to provide a novel jet spray tool which is easy and cheap to produce and yet reliable to use.
This object is achieved with a jet spray tool for frozen carbon dioxide particles com-prising a supply unit containing carbon dioxide gas under high pressure, for example 40-60 bar, a jet nozzle connected to the supply unit for receiving pressurised carbon dioxide gas from the supply unit and for producing a jet of frozen carbon dioxide par-ticles due to the expansion of the gas when exiting the nozzle, and a connection be-°' ~~F~~~~ ~'' tween the supply unit and the jet nozzle for transporting the pressurised carbon diox-ide gas from the supply unit to the jet nozzle.
In the above stated prior art, liquid carbon dioxide is supplied to the carbon dioxide snow producing nozzle. However, this has led to rather complicated arrangements.
In connection with the invention, it has surprisingly turned out, that carbon dioxide in gas form successfully can be used to produce frozen carbon dioxide at a nozzle due to the expansion of the pressurised gas. Typically such pressure is 40-60 atmospheres.
As experiments have indicated, an arrangement according to the invention, as de-scribed below, results in formation of a fast jet of carbon frozen dioxide particles leav-ing the nozzle. This jet behaves differently than typical snow jets known from ar-rangements, where liquid carbon dioxide is used. The effect has not yet been fully understood, but there are indications of frozen carbon particles in a physical/chemical phase that has not yet been observed foi° this kind of jet formation but which has proved to be very efficient for cleaning surfaces.
In practice, the supply unit may contain carbon dioxide gas and carbon dioxide liquid.
However, to assure gas extraction and not liquid extraction, the connection is con-nected to the supply unit above the carbon dioxide liquid level in the supply unit.
Thus, the connection may be connected to the supply unit at the uppermost point of it.
In order to control the release of snow from the nozzle, a valve is located between the supply unit and the nozzle.
If the length of the connection is very long, it takes a substantial length of time and waste of carbon dioxide, until a carbon dioxide particle jet forms at the nozzle. This is a disadvantage for intermitted operation of a jet spray nozzle. Therefore, the supply unit should be near to the nozzle, for example at a distance less than 500 mrn, such that the length of the connection is short. In a practical embodiment, the applied dis-tance between the extraction point of the supply unit and the nozzle has been set to 70 mrri, which has been proven to be particularly useful. However, a length of less than 200 mm can in certain instances be sufficient.
The rapid transport of gas from the intermediate chamber to the nozzle due to the short distance of the connection cools the nozzle so fast and efficient that a jet can be formed within less than a second after opening of the valve. Therefore, this system is easy to construct, cheap to produce and yet very reliable and precise even for intermit-tent jet application.
As a supply unit, a carbon dioxide bottle or tank can be used directly connected to the nozzle at a short distance. However, due to the short length of the connection between the supply and the nozzle, a large tank is disadvantageous near the nozzle.
Therefore, in a further embodiment, the carbon dioxide tank may be located at a larger distance and be connected to the supply unit for supply of carbon dioxide from the tank to the supply unit as an intermediate chamber close to the jet nozzle. This is especially useful where the distance between the carbon dioxide tank and the supply unit is much longer than the distance between the supply unit and the jet nozzle, for example more than an order of magnitude larger.
In experiments for cleaning surface, the internal volume of the intermediate chamber was about 50 cubic centimetres, and depending of the need, it is proposed to use a volume of the order of between 5 ccm and 500 ccm.
In the supply unit as an intermediate chamber, carbon dioxide is received and stored before further use at the nozzlee There may be stored carbon dioxide liquid in the in-termediate chamber together with carbon dioxide gas for extraction.
It may in some circumstances be an advantage that the intermediate chamber and the gas therein are cooled during the storage time, which in most circumstances is rela-tively short. For this cooling, the intermediate chamber has an opening into atmos-phere for exhaust of carbon dioxide, which causes cooling.
A. typical nozzle that has been used with success is tubular and comprises a lateral groove across the exit hole at the front end of the nozzle.
As an extra. feature, the jet spray tool according to the invention may comprise pre-y cooling arrangement for precooling the jet nozzle before ejection of a jet of frozen carbon dioxide particles, for, example in the form of snow, from the nozzle.
Such a precooling can be accomplished by, for instance, by a Peltier cooling element in ther-mal contact with the nozzle or by a container with liquid Helium in thermal contact with at least part of the nozzle. In this case, the nozzle can be precooled to a tempera-tore of at least below =40°C and preferably to the boiling temperature of liquid carbon dioxide.
SHORT DESCRIPTION OF THE DRAWINGS
The invention will be explained in more detail with reference to the drawing, where FIG. 1 is a diagram of the jet spray system with the spray tool, FIG. 2 is a sketch of a possible embodiment of the nozzle, FIG. 3 is a micrograph of an aluminium surface, FIG. 4 shows two micrographs in connection with a first cleaning process of an alu-minium surface using a slit nozzle with 0.8 mm size, FIG. 5 shows two micrographs in connection with a second cleaning process of an aluminium surface using a slit nozzle with 1.1 mm size, FIG. 6 shows two micrographs in connection with a third cleaning process of an alu-minium surface using a nozzle with a round exit hole with a diameter of 1.2 DETAILED DESCRIPTION l PREFERRED EMBODIMENT
Fig. 1 is a diagram of the jet spray system with a jet spray tool according to the inven-tion. The jet spray system 1 comprises a storage tank 2 for carbon dioxide liquid and gas, typically at a pressure of 40-60 atmospheres. The storage tank 2 is connected to a nozzle arrangement 9 with a nozzle 10, through which a jet of frozen carbon,dioxide particles 11 is ejected when carbon dioxide gas is supplied under high pressure. The connection 4, 6, 8 between the storage tank 2 and the nozzle 10 can be accomplished by stiff and/or flexible tubing that generally is used for this kind of arrangements. The carbon dioxide supply from the storage tank can be controlled by a valve 3.
5 Inserted between the storage tank 2 and the nozzle 10 is an intermediate chamber 5, where carbon dioxide supplied from the storage tank 2 can be stored for rapid extrac-tion. From the intermediate chamber, carbon dioxide gas can be supplied to the nozzle through the tubing 6, 8 when valve 7 is opened, where the extraction of carbon dioxide from the intermediate chamber 5 through the tubing 6 is above the liquid level 18 in the intermediate chamber in order to assure gas extraction. Alternatively, the extrac-tion can be from the top of the intermediate chamber in order always to assure gas extraction. As the intermediate chamber is only 70 mm from the nozzle, the supply of carbon dioxide gas to the nozzle from the intermediate chamber 5 is rapid enough to cause a fast cooling of the nozzle resulting in a formation of a carbon dioxide particle jet after a very short initial phase of cooling of less than a second. This is very suited .
for sequential spraying with time scales in the order of few seconds. The intermediate chamber 5 further comprises an opening 17 into atmosphere.
A nozzle arrangement 9 that can be used in a system according to the invention is i1-lustrated in Fig. 2. The nozzle arrangement 9 is connected to the tubing 8 by a stan-dard connection, for example a threaded fitting 13. The nozzle arrangement 9 com-prises a tubular nozzle 10 with a simple jet exit hole 16 inserted into a nozzle holder 14 fastened to the tube fitting 13. This nozzle arrangement 9 with the nozzle 10 is very simple in nature, though still providing a satisfactory jet 11 of carbon dioxide parti cles.
An improvement of the jet formation has been observed for nozzles 10 that are pro-vided with a lateral groove 15 across the front end of the nozzle 10 with the ejection hole 16, which is shown in an enlarged head-on perspective in Fig. 2b.
In the following, some experimental results are presented which are achieved with an arrangement according to the invention.
In FIG. 3, a micrograph of an aluminium surface is shown without a surface treatment with a jet tool. The width of the image is 1 micrometer. Three pieces of aluminium have been treated with three different jet tool nozzles in an arrangement according to the invention. The results are shown in FIG. 4, 5 and 6 for three different dies. For each of FIG. 4, 5, and 6, the right image shows an untreated part of the surface and the left image shows a corresponding surface treated with a carbon dioxide jet according to the invention. Beware that the width of the right images is 1 micrometer, whereas the left images have a width of 0.5 micrometer.
The dies used for FIG. 4 and 5 had slit formed nozzle holes with widths of 0.8 and 1.1 mm, respectively, whereas the die used for FIG. 6 had a circular nozzle exit hole with a diameter of 1.2 mm. Useful nozzle exit hole sizes have .been tested primarily in the range of 0; 8 to 3 mm. Nozzles with hole diameters of up to 10 mm have been used, however, the amount of carbon dioxide for a jet cleaning process increases largely for such large nozzles.
The form of the nozzle exit hole or holes depend on the desired use. For example, a nozzle has been used with a central hole formed as a slit and two side round holes. The distances from the nozzle to the probe were typically 15-25 mm and the gas pressure 60 bar.
As can be seen from FIG. 4, 5 and 6 in mutual comparison, the result in FIG. 6 is more pronounced than the other two results. As the crystals on the aluminium surface were distinctively smaller, a higher surface tension was achieved resulting in a more smooth glue layer on the surface.
In the experiment, where aluminium pieces afterwards were glued together, it turned out that the strength of the glue after the jet tool treatment as shown in FIG. 6 was comparable to the strength of glue after initial cleaning with isopropanol (IPA) which is the normal way used in industry. For steel and aluminium surfaces, strengths of more than 19 MPa were achieved. This is a great advantage, because cleaning with alcohol implies high costs and is environmentally disadvantageous. Thus, by the in-vention, a simple way with low costs has been found to substitute the undesired use of IPA in cleaning processes of surfaces, for example metal surfaces such as aluminium surfaces or steel surfaces.
Cleaning with IPA resulted in surfaces with approximately 2-3% of chemical rem-nants on the surface. In contrast, the cleaning with the carbon dioxide particle jet yielded a much cleaner surface, where the amount of remnants was less than 0.1 making this method highly useful for surfaces where the cleaning is critical.
The jet from the nozzle has been observed to behave differently than normal snow jets from prior art nozzles. Also, supply of liquid carbon dioxide to the nozzle did not lead to successful results. This indicates that the expansion of the highly pressurised gas leads to a special phase of carbon dioxide which has not yet been completely under-stood.
A nozzle according to the invention may comprise a central stop in front of the nozzle exit hole. This would result in a hollow conical jet which is suited for cleaning of sur-faces, where certain areas of the surface should not be hit by the jet. Such surfaces may be printed circuit boards with delicate electronic components.

Claims (10)

1. Jet spray tool for frozen carbon dioxide particles comprising - a supply unit containing carbon dioxide gas under high pressure, - a jet nozzle connected to the supply unit for receiving carbon dioxide gas under high pressure from the supply unit and for producing a jet of frozen carbon dioxide parti-cles, - a connection between the supply unit and the jet nozzle for transporting carbon diox-ide gas from the supply unit to the jet nozzle.
2. Jet spray tool according to claim 1, wherein the supply unit contains carbon dioxide gas and carbon dioxide liquid and where the connection is connected to the supply unit above the carbon dioxide liquid level in the supply unit to assure gas extraction from the supply unit.
3. Jet spray tool according to claim 1 or 2, wherein a valve is located between the sup-ply unit and the nozzle.
4. Jet spray tool according to according to any preceding claim, wherein the pressure of the carbon dioxide gas is 40-60 bar.
5. Jet spray tool according to according to any preceding claim, wherein the distance from the supply unit to the nozzle is less than 500 mm.
6. Jet spray tool according to any preceding claim, wherein the distance from a gas extraction point of the supply unit to the exit of the jet nozzle is less than 200 mm.
7. Jet spray tool according to any preceding claim, wherein the jet spray tool com-prises a carbon dioxide tank connected to the supply unit for supply of carbon dioxide from the tank to the supply unit as an intermediate chamber close to the jet nozzle, and where the distance between the carbon dioxide tank and the supply unit is more than an order of magnitude larger than the distance between the supply unit and the jet noz-zle.
8. Jet spray tool according to claim 7, wherein the internal volume of the intermediate chamber is of the order of between 0.05 and 10 decilitre.
9. Jet spray tool according to claim 7 or 8, wherein the intermediate chamber has an opening into atmosphere for evaporation of carbon dioxide.
10. Jet spray tool according to anyone of the preceding claims, wherein the nozzle is tubular and comprises a lateral groove across the exit hole at the front end of the noz-zle.
CA002531672A 2003-07-10 2004-07-09 Jet spray tool Abandoned CA2531672A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DKPA200301048 2003-07-10
DKPA200301048 2003-07-10
PCT/DK2004/000500 WO2005005064A1 (en) 2003-07-10 2004-07-09 Jet spray tool

Publications (1)

Publication Number Publication Date
CA2531672A1 true CA2531672A1 (en) 2005-01-20

Family

ID=34042635

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002531672A Abandoned CA2531672A1 (en) 2003-07-10 2004-07-09 Jet spray tool

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CA (1) CA2531672A1 (en)
WO (1) WO2005005064A1 (en)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1813733A (en) * 1928-07-30 1931-07-07 James J Freeman Hose nozzle
SE451362B (en) * 1985-08-09 1987-10-05 Hans Bengt Folke Moss BLASMUNSTYCKE
DE19615333A1 (en) * 1995-07-24 1997-01-30 Hewlett Packard Co Gas analyser partic. for human breath - incorporates an in-situ system using carbon di:oxide snow for cleaning optical surfaces and thus allowing the analysis chamber to remain closed
US5928434A (en) * 1998-07-13 1999-07-27 Ford Motor Company Method of mitigating electrostatic charge during cleaning of electronic circuit boards
JP4210045B2 (en) * 2001-06-25 2009-01-14 横河電機株式会社 Cleaning device

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Publication number Publication date
WO2005005064A1 (en) 2005-01-20

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