US2761997A - Apparatus for detecting surface discontinuities - Google Patents

Apparatus for detecting surface discontinuities Download PDF

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US2761997A
US2761997A US168214A US16821450A US2761997A US 2761997 A US2761997 A US 2761997A US 168214 A US168214 A US 168214A US 16821450 A US16821450 A US 16821450A US 2761997 A US2761997 A US 2761997A
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Prior art keywords
nozzle
conduit
particles
fluid
article
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Expired - Lifetime
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US168214A
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Forest Taber De
Henry N Staats
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Magnaflux Corp
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Magnaflux Corp
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Priority claimed from US701704A external-priority patent/US2515396A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/91—Investigating the presence of flaws or contamination using penetration of dyes, e.g. fluorescent ink
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B13/00—Measuring arrangements characterised by the use of fluids
    • G01B13/22—Measuring arrangements characterised by the use of fluids for measuring roughness or irregularity of surfaces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/34—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring roughness or irregularity of surfaces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/90—Investigating the presence of flaws or contamination in a container or its contents
    • G01N21/9054—Inspection of sealing surface and container finish

Definitions

  • the present invention relates to an apparatus for detecting surface discontinuities and more particularly to means for producing a finely particulated cloud of electrostatically charged particles suspended in a fluid n edium.
  • the present invention now provides an improved apparatus for forming an electrostatically charged cloud consisting of finely divided particulated material suspended in a fluid medium, preferably air.
  • the device disperses finely particulated material in a gaseous medium by the utilization of an aspirator, operating in accordance with the Bernoulli eltect.
  • the fluidsuspension of finely divided particles is then conveyed by suitable means to its point of use, an electrostatic charge being imparted to the particles, as by passing the particle clouds through a suitable rubber hose and nozzle or the like.
  • Another important object of the present invention is to provide aspirator means for forming a suspension of finely particulated solid material in a fluid and imparting an electrostatic charge to the particles while so suspended.
  • Figure 1 is a side elevational view, with parts broken away and in section of apparatus of the present invention
  • Figure 2 is a longitudinal sectional view of a modified form of nozzle for use with the apparatus of Figure 1;
  • Figure 3 is an additional modified form of nozzle
  • Figure 4 is a sectional view of still another modified form of nozzle.
  • reference numeral 10 refers generally to a containerof suitable shape provided with closed bottom and side walls and communicating through its upper Wall 11 with an upwardly diminishing passage 12 communicating with a reduced outlet orifice 13.
  • the container 10 has disposed therein a body 14 of finely particulated solid material.
  • the material i4 may be any finely divided solid, but we have found it preferable to employ non-hygroscopic inorganic substances capable of being highly charged electrostatically. Calcium carbonate, or precipitated chalk, has thus far been found to be one of best materials.
  • talc powdered mica, diatomaceous earth, clays such as kaolin, calcium sulfate, iron oxide, carbon black, aluminum powder, and many others.
  • the body 14 of particulated solid material within the container 10 is surmounted by a float plate 15 centrally apertured, as at 16, to receive a conduit or tube 1"] which in turn telescopically receives an upwardly extending flexible conduit or hose 18 formed of rubber or the like which extends through one of the side walls of the container 10 for communication with a source of fluid, such as air, under pressure through a supply pipe 19 and a valve 20.
  • the valve 20 communicates with a T fitting 21 in the supply line 19, and it will be seen that upon opening the valve 20 a charge of fluid under pressure is introduced into the container 10 directly upon the material 14 therein so that the material is agitated and will become suspended in fluid entering the container through the line 18.
  • the supply line 19 is provided with a second valve 22 located therein beyond the T-fitting 21, and the valve 22 is adapted to admit air under pressure into a reduced conduit 23 coaxial with and interiorly of an adapter fitting 24.
  • the adapter fitting 24 is provided with an intermediate depending reduced diameter conduit 24a which communicates with the reduced orifice 13 of the outlet passage 12 of the container 10 hereinbefore described.
  • the conduit 23 receiving air under pressure therethrough is supported in coaxial relation with the fitting 24 by means of a block 23a interposed therebetween, and the conduit 23 extends axially of the fitting 24 from the valve 22 to a point beyond the depending conduit 25.
  • the cooperating conduit 23 and the fitting 24 will function as an aspirator to produce a reduced pressure at the orifice 13 in accordance with the Bernoulli effect, and this reduced pressure will serve to draw the suspension of solids influid from'the container 14 into the fitting 24.
  • the cloud of suspended, finely particulated solid matter thus formed in the fitting 24 is conducted through a flexible conduit 25 which may be rubber to a pair of branched conduits 26 which-alsomay be rubber disposed immediately adjacent the upper portion of anarticle A to be tested.
  • the branched conduits 26 each terminate in a nozzle 27 immediately adjacent the article A.
  • the nozzles 27 each comprise a pair-of coaxial, axially extending stepped chambers 28 and 29, the larger of the chambers (29) receiving the-particulated cloud from the chamber 28 and'the conduit 26.
  • the nozzles 2'7 are preferably constructed ofhard rubber to produce an electrostatic' charge in the suspended solid matter of the cloud introduced therethrough as hereinbefore explained.
  • the nozzles may be made of phenol-tonnaldehyde resin, wood, paper, ethyl cellulose resin, or other similar materials capable of so producing an electrostatic charge.
  • the stepped bores 28 and 29 arereplaced by a single tapering bore 30 of increasing diameter toward the article A.
  • the nozzle 27 is formed of a first nozzle block 31 receiving the conduit 26 and a second cylindrical block 32 telescopically fitted over the nozzle block 31.
  • the nozzle block 31 is provided with an interior, generally cylindrical recess 33 and the nozzle 32 is pro vided with an internal axial bore 34 of greater diameter than the recess 33.
  • the nozzle 27 is substantially identical with that hereinbefore illustrated and described in Figure l with the addition of a terminal deflector block 35 telescopically mounted on the nozzle block 27 and provided with the downturned deflector tip 36.
  • the purpose of the stepped bores, or the frusto-conical bore of the embodiment of Figure 2 is to produce a spraying nozzle action to uniformly distribute the pewdered cloud acting through the nozzle over the surface of the article A to be tested.
  • the telescoping adjustment of the nozzle sleeve 32 relative to the block 31 makes possible the adjustment of the angle of the spray, thereby accommodating the employment of this form of nozzle to various sizes and types of articles being tested.
  • the deflector plate 36 insures the direction of the electrostatic cloud either along the entire length of the article A to be tested or to a specific portion of the article. It will be appreciated that the deflector block 35 is telescopically mounted on the nozzle 27 for axial adjustment for varying the angle of the spray and the location to which it is deflected.
  • thepresent-invention provides novel means for form ing a cloud of electrostatically charged solid particles suspended in a fluid medium.
  • a fluid medium for most applications it is desirable to employ compressed air for economic reasons.
  • any suitable fluid under pressure may be employed as desired.
  • An apparatus for spraying electrostatically charged particles over a wetted surface of glass or the like to deect surfacediscontinuities a conduit of electrical insulation material for a pressurized fluid medium having finely divided particulate materialdispersed therein, and a nozzle also of electrical insulation material on said conduit for directing the fluid medium and particulate material against the surfaceofan article under test, said nozzle being formed of adjustable telescoping portions defining a cylindrical inlet chamber and a cylindrical outlet chamber having a diameter substantially greater than the diameter of said inlet chamber, for obtaining increased turbulence in the fluid medium and increased frictional contact-of the particles with the interior surface of said nozzlewhile reducing the velocity of the fluid stream.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Description

Sept. 4, 1956 1-, DE FOREST EI'AL 2,761,997
APPARATUS FOR DETECTING SURFACE DISCONTINUITIES Original Filed Oct. '7, 1946 fziz arzfar" 5 7, 45, 79 DEAF-5,6587
1751/0) A. S urs ilnited States PatentO APPARATUS FOR DETECTING SURFACE DISCONTINUITIES Taber de Forest, Northbrook, and Henry N. Staats, Chicage, Ill., assignors to Magnaflux Corporation, Chicago, 111., a corporation of Delaware Original application October 7,1946, Serial No. 701,704. 136iit2iig and this application June 15, 1950, Serial No.
1 Claim. (Cl. 317-3) The present invention relates to an apparatus for detecting surface discontinuities and more particularly to means for producing a finely particulated cloud of electrostatically charged particles suspended in a fluid n edium.
This application is a division of our application of the same title, Serial No. 701,704, filed October 7, 1946, now U. S. Letters Patent 2,515,396, issued July 18, 1950, and a continuation-in-part of our application Serial No. 648,234, filed January 18, 1946, now U. S. Letters Patent No. 2,499,466, issued March- 7, 1950, both of said applications being assigned to the assignee of the instant invention.
We have found, as fully disclosed in the above identified applications, that surface discontinuities may be detected in poorly conductive articles, such as glass botties, or the like, by first wetting the bottles with water or a Water-miscible liquid; drying the surface superficially; introducing finely particulated electrostatic particles onto the superficially dried surface; and finally observing any concentration of particulated material at the surface of the article. Under the conditions above outlined, electrostatically charged particles accumulate at or on any surface discontinuities, or cracks in the article in well-defined comparatively dense conglomeratio-ns which are coextensive with the cracks. The resulting definite visual indication not only indicates the presence of cracks, but indicates the extent of such defects.
The present invention now provides an improved apparatus for forming an electrostatically charged cloud consisting of finely divided particulated material suspended in a fluid medium, preferably air. The device disperses finely particulated material in a gaseous medium by the utilization of an aspirator, operating in accordance with the Bernoulli eltect. The fluidsuspension of finely divided particles is then conveyed by suitable means to its point of use, an electrostatic charge being imparted to the particles, as by passing the particle clouds through a suitable rubber hose and nozzle or the like.
it is, therefore, an important object of the present invention to provide an improved apparatus for the de tection of surface discontinuities by the formation of a finely divided cloud of electrostatically charged particles and means for introducing the particles onto an article to be tested.
Another important object of the present invention is to provide aspirator means for forming a suspension of finely particulated solid material in a fluid and imparting an electrostatic charge to the particles while so suspended.
It is a further important object of the present invention to provide an apparatus for the detection of surface discontinuities in an electrically non-conductive material, including means for utilizing the Bernoulli eflect to form a suspension of finely particulated solid material in a fluid, directing the suspension against an article to be tested, and imparting an electrostatic charge to the suspension particles.
It is a still further important object of the present invention to provide an improved apparatus for forming a suspension of electrostatically charged solid particles in a fluid, including aspirator means for forming the suspension of solid material in a fluid stream, and anonconductive nozzle for directing the suspension against an article to be tested, the nozzle serving to impart to particles passing therethrough an electrostatic charge.
Other and further important objects of this invention will be apparent from the disclosures in the specification and accompanying drawings.
On the drawings:
Figure 1 is a side elevational view, with parts broken away and in section of apparatus of the present invention;
Figure 2 is a longitudinal sectional view of a modified form of nozzle for use with the apparatus of Figure 1;
Figure 3 is an additional modified form of nozzle; and
Figure 4 is a sectional view of still another modified form of nozzle.
As shown on the drawings:
In Figure 1 reference numeral 10 refers generally to a containerof suitable shape provided with closed bottom and side walls and communicating through its upper Wall 11 with an upwardly diminishing passage 12 communicating with a reduced outlet orifice 13. The container 10 has disposed therein a body 14 of finely particulated solid material. In general the material i4 may be any finely divided solid, but we have found it preferable to employ non-hygroscopic inorganic substances capable of being highly charged electrostatically. Calcium carbonate, or precipitated chalk, has thus far been found to be one of best materials. However, it is possible to employ talc, powdered mica, diatomaceous earth, clays such as kaolin, calcium sulfate, iron oxide, carbon black, aluminum powder, and many others.
The body 14 of particulated solid material within the container 10 is surmounted by a float plate 15 centrally apertured, as at 16, to receive a conduit or tube 1"] which in turn telescopically receives an upwardly extending flexible conduit or hose 18 formed of rubber or the like which extends through one of the side walls of the container 10 for communication with a source of fluid, such as air, under pressure through a supply pipe 19 and a valve 20. The valve 20 communicates with a T fitting 21 in the supply line 19, and it will be seen that upon opening the valve 20 a charge of fluid under pressure is introduced into the container 10 directly upon the material 14 therein so that the material is agitated and will become suspended in fluid entering the container through the line 18. The supply line 19 is provided with a second valve 22 located therein beyond the T-fitting 21, and the valve 22 is adapted to admit air under pressure into a reduced conduit 23 coaxial with and interiorly of an adapter fitting 24. The adapter fitting 24 is provided with an intermediate depending reduced diameter conduit 24a which communicates with the reduced orifice 13 of the outlet passage 12 of the container 10 hereinbefore described. The conduit 23 receiving air under pressure therethrough is supported in coaxial relation with the fitting 24 by means of a block 23a interposed therebetween, and the conduit 23 extends axially of the fitting 24 from the valve 22 to a point beyond the depending conduit 25.
It will be appreciated by those skilled in the art that the cooperating conduit 23 and the fitting 24 will function as an aspirator to produce a reduced pressure at the orifice 13 in accordance with the Bernoulli effect, and this reduced pressure will serve to draw the suspension of solids influid from'the container 14 into the fitting 24. The cloud of suspended, finely particulated solid matter thus formed in the fitting 24 .is conducted through a flexible conduit 25 which may be rubber to a pair of branched conduits 26 which-alsomay be rubber disposed immediately adjacent the upper portion of anarticle A to be tested. The branched conduits 26 each terminate in a nozzle 27 immediately adjacent the article A.
The nozzles 27 each comprise a pair-of coaxial, axially extending stepped chambers 28 and 29, the larger of the chambers (29) receiving the-particulated cloud from the chamber 28 and'the conduit 26. The nozzles 2'7 are preferably constructed ofhard rubber to produce an electrostatic' charge in the suspended solid matter of the cloud introduced therethrough as hereinbefore explained. Alternately, thenozzles may be made of phenol-tonnaldehyde resin, wood, paper, ethyl cellulose resin, or other similar materials capable of so producing an electrostatic charge.
In that form of nozzle illustrated in Figure 2, the stepped bores 28 and 29 arereplaced by a single tapering bore 30 of increasing diameter toward the article A. In Figure 3 the nozzle 27 is formed of a first nozzle block 31 receiving the conduit 26 and a second cylindrical block 32 telescopically fitted over the nozzle block 31. The nozzle block 31 is provided with an interior, generally cylindrical recess 33 and the nozzle 32 is pro vided with an internal axial bore 34 of greater diameter than the recess 33.
In Figure 4 of the drawings, the nozzle 27 is substantially identical with that hereinbefore illustrated and described in Figure l with the addition of a terminal deflector block 35 telescopically mounted on the nozzle block 27 and provided with the downturned deflector tip 36.
The purpose of the stepped bores, or the frusto-conical bore of the embodiment of Figure 2, is to produce a spraying nozzle action to uniformly distribute the pewdered cloud acting through the nozzle over the surface of the article A to be tested. In the embodiment of Figure 3, the telescoping adjustment of the nozzle sleeve 32 relative to the block 31 makes possible the adjustment of the angle of the spray, thereby accommodating the employment of this form of nozzle to various sizes and types of articles being tested. In the embodiment of Figure 4, the deflector plate 36 insures the direction of the electrostatic cloud either along the entire length of the article A to be tested or to a specific portion of the article. It will be appreciated that the deflector block 35 is telescopically mounted on the nozzle 27 for axial adjustment for varying the angle of the spray and the location to which it is deflected.
From the foregoing description, it will be appreciated that thepresent-invention provides novel means for form ing a cloud of electrostatically charged solid particles suspended in a fluid medium. Obviously, for most applications it is desirable to employ compressed air for economic reasons. However, any suitable fluid under pressure may be employed as desired.
It will be understood that modifications and variations may be eifected Without departing from the scope of the novel concepts of the present invention.
2 claim as my invention:
An apparatus for spraying electrostatically charged particles over a wetted surface of glass or the like to deect surfacediscontinuities, a conduit of electrical insulation material for a pressurized fluid medium having finely divided particulate materialdispersed therein, and a nozzle also of electrical insulation material on said conduit for directing the fluid medium and particulate material against the surfaceofan article under test, said nozzle being formed of adjustable telescoping portions defining a cylindrical inlet chamber and a cylindrical outlet chamber having a diameter substantially greater than the diameter of said inlet chamber, for obtaining increased turbulence in the fluid medium and increased frictional contact-of the particles with the interior surface of said nozzlewhile reducing the velocity of the fluid stream.
References Cited in the file of this patent UNITED STATES PATENTS 1,349,751 Cross Aug. 17, 1920 1,736,969 Greiser Nov. 26, 1929 1,928,963 Chafiee Oct. 3, 1933 2,058,218 Duccini et a1. Oct. 20, 1936 2,091,055 Roselund et a1. Aug. 24, 1937 2,114,682 Gumaer Apr. 19, 1938 2,165,946 Smith July ll, 1939 2,297,791 Ness Oct. 6, 1942 2,302,185 Campbell Nov. 17, 1942 2,396,533 Root Mar. 12, D46 2,477,947 Yadoff Aug. 2, 1949 2,590,534 Hampe Mar. 25, i952 2,657,339 Hampe Oct. 27, 1953 2,659,841 Hampe Nov. 17, 1953 OTHER REFERENCES Static Electricity, U. S. Dept. of Commerce, National Bureau of Standards, Circular C438.
US168214A 1946-10-07 1950-06-15 Apparatus for detecting surface discontinuities Expired - Lifetime US2761997A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3536514A (en) * 1963-06-13 1970-10-27 Ransburg Electro Coating Corp Electrostatic coating method
US3903321A (en) * 1972-01-25 1975-09-02 Hans J Schaad Method for charging plastic powder electrostatically by friction only
US6156392A (en) * 1999-07-13 2000-12-05 Nylok Fastener Corporation Process for triboelectric application of a fluoropolymer coating to a threaded fastener
US20070054052A1 (en) * 2005-06-01 2007-03-08 Gregory Alaimo Fluoropolymer coating compositions for threaded fasteners

Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1349751A (en) * 1919-02-12 1920-08-17 Harry N Cross Dust-fuel carbureter
US1736969A (en) * 1927-12-15 1929-11-26 Greiser Erich Atomizing device for pulverulent material
US1928963A (en) * 1925-01-12 1933-10-03 Donald W Salisbury Electrical system and method
US2058218A (en) * 1934-04-17 1936-10-20 Duceini Gaetano Apparatus for producing vitreous or metallic surfaces
US2091055A (en) * 1936-02-25 1937-08-24 Vilbiss Co Flock spraying apparatus
US2114682A (en) * 1935-06-28 1938-04-19 Percy W Gumaer Method and apparatus for electrical precipitation of dust
US2165946A (en) * 1936-07-30 1939-07-11 Wingfoot Corp Handling of dusts, etc.
US2297791A (en) * 1938-05-25 1942-10-06 Harold J Ness Atomizing device for pulverulent material
US2302185A (en) * 1940-07-27 1942-11-17 Union Oil Co Electrified spray apparatus
US2396533A (en) * 1943-05-24 1946-03-12 Root Mfg Company Dusting apparatus
US2477947A (en) * 1945-01-30 1949-08-02 Electronic Dusting Corp Method and device for projecting powders carrying electrostatic charges
US2590534A (en) * 1947-07-23 1952-03-25 Georges Truffaut Ets Apparatus for producing electrified powders by friction
US2657339A (en) * 1953-10-27 Method and apparatus for producing
US2659841A (en) * 1948-08-03 1953-11-17 Georges Truffaut Ets Means for electrifying pulverulent materials

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2657339A (en) * 1953-10-27 Method and apparatus for producing
US1349751A (en) * 1919-02-12 1920-08-17 Harry N Cross Dust-fuel carbureter
US1928963A (en) * 1925-01-12 1933-10-03 Donald W Salisbury Electrical system and method
US1736969A (en) * 1927-12-15 1929-11-26 Greiser Erich Atomizing device for pulverulent material
US2058218A (en) * 1934-04-17 1936-10-20 Duceini Gaetano Apparatus for producing vitreous or metallic surfaces
US2114682A (en) * 1935-06-28 1938-04-19 Percy W Gumaer Method and apparatus for electrical precipitation of dust
US2091055A (en) * 1936-02-25 1937-08-24 Vilbiss Co Flock spraying apparatus
US2165946A (en) * 1936-07-30 1939-07-11 Wingfoot Corp Handling of dusts, etc.
US2297791A (en) * 1938-05-25 1942-10-06 Harold J Ness Atomizing device for pulverulent material
US2302185A (en) * 1940-07-27 1942-11-17 Union Oil Co Electrified spray apparatus
US2396533A (en) * 1943-05-24 1946-03-12 Root Mfg Company Dusting apparatus
US2477947A (en) * 1945-01-30 1949-08-02 Electronic Dusting Corp Method and device for projecting powders carrying electrostatic charges
US2590534A (en) * 1947-07-23 1952-03-25 Georges Truffaut Ets Apparatus for producing electrified powders by friction
US2659841A (en) * 1948-08-03 1953-11-17 Georges Truffaut Ets Means for electrifying pulverulent materials

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3536514A (en) * 1963-06-13 1970-10-27 Ransburg Electro Coating Corp Electrostatic coating method
US4114564A (en) * 1963-06-13 1978-09-19 Ransburg Corporation Electrostatic coating apparatus
US3903321A (en) * 1972-01-25 1975-09-02 Hans J Schaad Method for charging plastic powder electrostatically by friction only
US6156392A (en) * 1999-07-13 2000-12-05 Nylok Fastener Corporation Process for triboelectric application of a fluoropolymer coating to a threaded fastener
US20070054052A1 (en) * 2005-06-01 2007-03-08 Gregory Alaimo Fluoropolymer coating compositions for threaded fasteners

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