US2753459A

US2753459A - Inspecting interior surfaces of glass

Info

Publication number: US2753459A
Authority: US
Publication date: 1956-07-03
Anticipated expiration: 1973-07-03

Description

INSPECTING INTERIOR SURFACES 0F GLASS CONTAINERS July 3, 1956 w. J. FEDORCHAK 2 Sheets-Sheet 1 Filed Dec.

f a w 2 Sheets Sheer,

W- J. FEDQFifii-iAK INSPECTING INTERIOR SURFACES OF GLASS CONTAINERS July 1956 Filed Dec.

Unite States Patent INSPECTING INTERIOR SURFACES OF GLASS (ZONTAINERS William J. Fedorchak, Granite Qity,

lit assignor to OWCIlS-lllllllOiS Glass Company,

My invention relates to methods and apparatus for inspecting the interior surfaces of containers such as glass bottles, jars, and the like, for the purpose of detecting surface fiaws such as sharp projections, known as spikes, and other surface defects including particles or fragments of glass either loose or adhered to the wall surface of the container. The invention is of use for inspecting containers made of various materials, including ceramics and the like and is of special utility for inspecting glass jars or containers in which food products or other commodities are packed. The ordinary methods of inspecting the interiors of such containers are inadequate and unreliable. On the other hand it is very important that such containers, particularly where used for packaging food products, be adequately inspected and any which contain fragments of glass or any so-called spikes or other jagged or protruding particles of glass, should be discovered and the article discarded. The occasional appearance of such defects in glass jars, for example, is unavoidable with present day methods of blowing the jars.

The present invention provides an apparatus designed for scanning the interior surfaces of open mouth containers in succession by means of a beam of light or radiant energy and causing the reflection of the beam from a surface defect to energize a photoelectric cell. The signal or impulse given by the cell is amplified and used to actuate any desired form of indicator and/or means for segregating the faulty article from those which pass the inspection.

Prior art methods and devices designed for inspecting the interiors of glass containers by means of a light beam for detecting interior surface flaws have proved to be unreliable and impractical. This is due in part to the fact that such devices are actuated by flaws and irregularities in the outer wall surfaces including seams, lettering or designs blown in the glass, color designs, etc., thereby giving false signals.

An object of the present invention is to overcome such difficulty. In its preferred form it provides means for directing a beam of radiation through the open mouth of the container and focusing it on the interior wall surface and causing the beam to scan such surface. In order to prevent the beam from being affected by exterior surface irregularities or flaws, it may be supplied by a source of ultra-violet radiation or radiation outside of the range of wave lengths to which the glass forming the container is transparent. As the radiation does not penetrate the glass, the beam is unaffected by the condition of the exterior surface of the container.

The apparatus may comprise a light source or source of radiation in the form of an electric arc lamp rich in ultraviolet rays. The light beam or beam of radiation is condenser and directed through the open mouth of the container and onto the interior surface of the container wall and is caused to scan said surface. To produce the scanning movement of the beam, the lamp is preferably mounted for oscillating movement by which the beam is caused to move radially across the bottom surface and vertically along the inner Wall surface. At the same time the con tainer is rapidly rotated about a vertical axis so that the beam traverses a spiral path and thus scans the entire interior surface of the container.

The radiation reflected from the inner wall surface of the container is passed through a condensing lens or lenses and directed against a photoelectric cell. Any foreign body such as a fragment of glass or other surface defect when brought into the light beam produces a sudden change or increase in the reflected radiation and thereby energizes the cell. The impulse from the cell is amplified and operates through suitable mechanism to automatically segregate the defective article from those which pass inspection.

This application discloses subject matter also disclosed in my copending applications, Serial No. 133,415, filed December 16, 1949, now Patent No. 2,649,500, Inspecting Method and Apparatus, and Serial No. 140,240, filed January 24, 1950, now Patent Nov 2,593,127, Electronic Inspection of Glass Containers.

Referring to the accompanying drawings:

Fig. 1 is a perspective view, with parts broken away and parts in section, illustrating an apparatus embodying the present invention;

Fig. 2 is a part sectional elevation showing means for rotating a container and mechanism for oscillating the lamp; and

Fig. 3 is a wiring diagram of the apparatus.

Referring to Figs. 1 and 2, the article 5 which is being inspected is shown as a glass jar. The jar is supported on a rotary disk or pad 6 attached to a stem 7 journaled in a stationary base 8. Keyed to the stem 7 is a pulley 9 driven by a belt 10 for rotating the jar during inspection. A post 12 rising from the base 8 provides a support for a photoelectric tube 13 and an amplifier 14. A light source 13 or source of radiant energy may consist of an arc lamp rich in ultra-violet radiation of a highly concentrated nature. The lamp is enclosed in a tubular holder 16 which comprises telescoping sections, the upper one containing condensing lenses 17 of quartz or other suitable material. The beam of radiation, after passing through the lenses, is reflected by a reflector 18 and the reflected beam 19 is directed through the open mouth of the container and focused to a spot at the point 20 on the inner wall surface of the container. This spot is near the focal point of the beam and may be, for example, approximately in diameter.

The lamp holder 16 is mounted on a rocking member 21 for oscillating or rocking movement in a vertical plane. The rocker 21 is carried on a pivot pin 22 mounted in a casing 23. A drive shaft 24 journaled in the casing carries a cam 25 on which runs a cam follower roll 26 on the rocker 21, said roll being held to the cam by a spring 27. As the cam rotates, it swings the lamp holder 16 from the full line position (Fig. 2) to the broken line position 16. When the lamp holder is in the full line position with the reflector 18 lowered, the light beam assumes a position 19 in which it is focused at the center of the floor 28 of the container. As the lamp carrier swings from such position, the beam traverses the bottom 28 of the container in a radial direction to the position 19' and thence upwardly along the inner vertical side Wall of the container.

While the beam is thus moving the container is rotated comparatively rapidly about its axis so that the spot of light is moved relative to the container in a spiral path and thus scans the bottom and side walls of the container. The speed of rotation of the container relative to the speed of the oscillating beam, is such that the entire surface under test is scanned by the spot of light or radiation. When a spike 30 or a fragment 31 of glass or the like, adhering to the container wall, comes into the light beam, there is a sudden change or increase in the amount of light or radiation reflected upwardly to the photoelectric cell. The reflected light is directed upwardly through condensing lenses 32 mounted in a tube 33 which may comprise telescoping sections permitting adjustment of the lens. The condensed beam of radiation is directed against the cathode 34 of the photoelectric cell. The cell is mounted in a shell 35 to cut off the ambient light.

The photoelectric cell is preferably chosen to have a sensitivity to radiation of comparatively short wave lengths and corresponding to the short wave radiation supplied by the lamp 15. I have found that a tube having a maximum sensitivity of between 2400 and 2500 angstroms and which cuts off at 3000 angstroms, gives highly satisfactory results in testing glass jars. The glass ordinarily used in the manufacture of such jars cuts off light transmission of wave lengths of about 3190 angstroms and shorter. Accordingly, the glass walls of the container are opaque to any radiation to which the photoelectric cell is sensitive, so that no signal can be transmitted to the cell from the outer wall surface of the container.

Referring to the wiring diagram (Fig. 3) power is supplied through a transformer comprising a primary coil 36,- and a secondary coil 37 connected to a rectifier 38, A secondary coil 39 supplies the current to the heater element 40 of the amplifier tube 14 and the heater 41 of a gas filled tube or Thyratron 42. A heating coil 43 for the rectifier 38 is supplied by a secondary coil 44.

When the photoelectric cell is actuated as above described, the impulse is amplified by the tube 14, the plate circuit of which feeds the Thyratron 42, and fires the latter. A signal lamp 45 and a relay coil 46 are connected in the plate circuit of the tube 42 so that when the tube is fired, the lamp 45 is lighted to give a signal. The coil 46 when energized, closes a relay switch 47.

The articles to be tested may be brought in rapid succession to the testing station by automatic mechanism (not shown), tested and conveyed from the testing station by a traveling conveyor. When the photoelectric cell is actuated as above described, the closing of the relay switch 47 establishes a circuit for a reject mechanism which is thereby set and operates to segregate the defective article from those which pass the test.

Modifications may be resorted to within the spirit and V scope of my invention.

I claim:

1. The method of inspecting the interior cylindrical wall surface of an open mouth container which comprises projecting a beam of radiation from a source of radiant energy, directing the beam through the open mouth of the container, focusing the beam to a small spot on the said surface, rotating the container about its axis and simultaneous'ly causing a relative movement of the said spot and the container in a direction parallel with said axis and thereby scanning the surface with said spot, and causing a flaw at said surface to reflect the radiation and direct it to a photoelectric cell sensitive to such radiation and thereby produce an electrical impulse, amplifying the impulse, and causing the amplified impulse to actuate a signal.

2. The method of inspecting an open mouth glass container for detecting fragments of glass or other foreign bodies or defects at the inner wall surface of the container, which method comprises projecting a beam of radiation from a source of radiation, condensing the beam and directing it through the open mouth of the container against the said inner wall surface, oscillating the beam in a plane of the axis of the container and simultaneously rotating the container about its axis and thereby causing the beam to scan said inner wall surface and causing any said surface defect to reflect radiation, directing the reflected radiation against the cathode of a photoelectric cell and thereby causing an electrical impulse in the cell circuit, amplifying said impulse, and actuating indicating means by the amplified impulse.

3. The method defined in claim 2', said method including shielding the photoelectric cell from radiation reflectedfrom any reflecting surfaces on the exterior of the container wall by maintaining the wave length of the radiation beam mainly below that to which the glass is transparent, the said radiation consisting mainly of ultra-violet rays to which the photoelectric cell is sensitive and to which the glass forming the container is opaque.

4. The method of inspecting the interior cylindrical wall surface of an open mouth container, which method comprises projecting a beam of radiation from a source of radiant energy, directing the beam through the open mouth of the container, focusing the beam to a small spot or area on the said surface, causing a relative rotation of said surface and spot about the axis of said cylindrical surface through a multiplicity of revolutions and a simultaneous relative movement of said surface and said spot in a direction parallel with the said axis, the relative speed and extent of said movements being such that substantially the entire area of said cylindrical surface between the starting and finishing revolutions is scanned by the said spot, and causing a flaw at said surface to reflect the radiation and direct it to a photoelectric cell sensitive to such radiation, thereby producing an electrical impulse.

5. The combination of a support journaled for rotation about the vertical axis of an open-mouth glass container supported thereon, means for rotating said support about the said axis and thereby rotating the container about its axis, a lamp mounted exterior to and laterally of the container, means for condensing a light beam from said lamp and directing the beam through the open mouth of the rotating container and thereby producing a spot of light on the inner wall surface of the container, means for oscillating the light beam in a substantially vertical plane simultaneously with the rotation of said container, and thereby causing the spot of light to scan said surface, a photoelectric cell mounted exterior to the container, means for condensing light reflected from a defect or foreign body at said surface and directing the reflected light to the photoelectric cell and thereby energizing the cell, said condensing means comprising condensing lenses mounted directly over the open mouth of the container.

6. The apparatus defined in claim 5, said apparatus comprising a holder in which the lamp is mounted, the directing means for the light beam comprising a reflector carried by said holder in the path of the light beam projected from the lamp and arranged to reflect the light beam and direct it into the container, the said means for oscillating the light beam comprising means for oscillating the lamp holder about a horizontal axis.

7. Apparatus for testing the inner wall surface of an open-mouth container, said apparatus comprising a horizontally disposed support for the container, said support mounted for rotation about the vertical axis of the con tainer while the container is supported in an upright position thereon, means for rotating the support and thereby rotating the container about its said axis, a source of radiant energy, means for supporting said source in a position exterior to the container, means for directing a beam of radiation from said source in a path which extends downwardly through the open mouth of the container and condensing and focusing the beam to a small spot on the said inner surface, means for oscillating said source of energy and with it the beam of radiation about an axis perpendicular to the axis of the container simultaneously with the rotation of the container about its axis and thereby causing the beam to scan said inner surface, a photoelectric cell sensitive to said radiation, means for mounting the cell over the mouth of the container in the path of radiation of said beam reflected upwardly through the mouth of the container by a foreign body at said surface, whereby the photoelectric cell is energized by said reflected radiation and an impulse produced in the cell circuit, means for amplifying the impulse, and signaling means actuated by the amplified impulse.

8. The apparatus defined in claim 7, the said container consisting of glass, said source of radiant energy consisting of an arc lamp rich in ultra-violet radiation of a wave length to which the glass is opaque.

9. The combination of a horizontally disposed supporting pad journaled for rotation about a vertical axis and forming a support for an open-mouth glass jar mounted in an upright position on the pad co-axial with the said pad, means for rotating the pad and the jar thereon about said vertical axis, a lamp mounted exterior to the said jar, means for condensing a light beam from said lamp, means for directing the beam in a path which extends above and downwardly through the open mouth of the rotating jar and thereby producing a spot of light on the inner wall surface of the jar, means for oscillating the said directing means about a horizontal axis and thereby oscillating the said light beam in a substantially vertical plane simulta neously with the rotation of the container and thereby causing this spot of light to scan said surface, a photoelectric cell, means for condensing light reflected from a defect or foreign body at said surface when brought within the path of said beam and directing the reflected light to the photoelectric cell and thereby energizing the cell.

10. Apparatus for inspecting the interior surface of an open-mouth glass container, said apparatus comprising means for supporting the container in a predetermined position, a lamp, a holder in which the lamp is mounted, said holder being positioned exterior to the container and laterally thereof and mounted for swinging movement about an axis perpendicular to the axis of the container, at condensing lens mounted in the holder for condensing a beam of radiation from said lamp, a reflector mounted in said holder in the path of the beam and positioned over the mouth of the container at an angle to direct the reflected beam through the open mouth of the container against said inner surface, means for rotating the container about its axis and simultaneously swinging said holder and parts mounted therein as a unit about the said axis of the holder and thereby causing the beam to scan said surface, a cell sensitive to radiation from said lamp, means for directing a portion of the radiation reflected from a flaw at said surface to the said cell when the flaw is brought into the path of said beam and thereby energizing the cell and producing an impulse in the circuit of said cell, and means for amplifying the impulse and producing a signal.

11. The method of inspecting a surface of transparent glass to detect loose glass or defects at said surface, which method comprises impinging on said surface incident radiation of wave length outside of the range of radiation transmissible through the glass and positioning an element sensitive to said radiation in the path of a portion of the radiation reflected in a predetermined direction by a defect at said surface when the defect is brought into the path of the incident radiation and thereby energizing said element and producing a signal.

12. The method defined in claim 11, the radiation consisting mainly of ultra-violet radiation and said element comprising a photoelectric cell.

13. The method defined in claim 11, said incident radia tion being in the form of a beam, the method including condensing the beam toward a focal point adjacent to said surface and relatively moving said surface and said beam in a path such that the beam is caused to scan the said surface.

14. The method of inspecting the interior surface of a hollow transparent glass container to detect defects or flaws at said surface, which method comprises generating radiation of a wave length not transmissible through the glass, directing a beam of said radiation from a point exterior to the container through the open mouth of the container to said interior surface and thereby impinging the beam on said surface, condensing the beam to a small spot at said surface, scanning the said surface with said spot, positioning an element sensitive to radiation of said wave length in the path of a portion of said radiation reflected by a flaw at said surface when the flaw is brought into the path of said beam, thereby producing a signal, and maintaining the path of said radiation beam entirely separate from the container Wails throughout said scanning except at the point of said impingement.

15. The method defined in claim 14, the said sensitive element comprising a photoelectric cell, the method including amplifying the impulse produced in said cell by the sudden change in the amount of said radiation striking the cell when the said flaw is brought into the path of the scanning beam, and actuating a signal device by said amplified impulse.

16. Apparatus for detecting foreign bodies on or at the inner surface of an open-mouth jar or container, said apparatus comprising a horizontally disposed support for the container mounted for rotation about a vertical axis while the container is supported thereon with its axis coinciding with that of the said support, an assembly comprising a light source, means for condensing a beam of radiation from said source and a reflector in the path of said radiation, means for mounting said assembly for oscillation at one side of the container, with said reflector above the mouth of the container and at an angle such that the beam reflected thereby is directed through the open mouth of the container to a point at said inner surface and with the walls of the container entirely outside of the path of said beam except at said point, means for oscillating said unit and simultaneously rotating said support and container and thereby causing said beam to scan said inner surface of the container, an element sensitive to said radiation positioned in the path of radiation reflected from a flaw at said surface when the flaw is brought into the path of said beam during the scanning, and signaling means actuated by said sensitive element.

17. The apparatus defined in claim 16, the walls of the containers being transparent and said light source comprising a lamp having short wave radiation to which the said walls of the container are opaque and thereby prevent the transmission of radiation to and from the exterior surface of the container.

18. The method of inspecting an open-mouth glass container for detecting fragments of glass or other foreign bodies or defects at the inner wall surface of the container, which method comprises projecting a beam of radiation and directing it through the open mouth of the container against the said surface, simultaneously causing relative motion between said beam and container in such a manner that the beam scans the said surface in. a spiral path, placing a detecting means sensitive to such radiation in position to receive a portion of the radiation reflected from said surface through the mouth of the container, and detecting a defect on the inner wall surface of said container by a signal given by said detecting means and caused by the sudden change in the radiation out of the mouth of said container produced by bringing the defect into contact with the said beam.

19. The method of inspecting an open-mouth glass container for detecting fragments of glass or other foreign bodies or defects at the inner wall surface of the container, which method comprises projecting a beam of radiation and directing it through the open mouth of the container against the inner wall surface, said radiation consisting mainly of ultra-violet rays to which the glass forming the container is opaque, oscillating the beam in a plane of the axis of the container and simultaneously rotating the container about its axis and thereby causing the beam to scan said inner wall surface, placing a detecting means sensitive to such radiation in position to receive a portion of the radiation reflected from said surface through the mouth of the container, and detecting a defect on the inner wall surface of said container by a signal given by said detecting means and caused by the sudden change in the radiation out of the mouth of said container produced by the movement of the defect into the path of the scanning beam.

20. The method of inspecting an interior surface of a glass container, comprising directing a narrow beam of ultraviolet light to said surface, substantially all of said light being of wavelengths impenetrable in said container, effecting both relative rotational movement and relative vertical movement simultaneously between said surface and said beam, and detecting changes in intensity of the reflection of said beam from said surface.

21. Apparatus for inspecting a surface of a glass body, comprising a source of ultraviolet light, means for directing a narrow beam of light from said source to said surface, photoelectric means positioned to intercept a part of said beam reflected from said surface, and means for detecting changes in the' output of said photoelectric means, substantially all of said light being of wave lengths of said beam reflected from said surface, and means for detecting changes in the output of said photoelectric means, substantially all of said light being of wave lengths impenetrable in said body.

References Cited in the file of this patent UNITED STATES PATENTS 1,648,058 Parker Nov. 8, 1927 10 1,897,141 Peters Feb. 14, 1933 2,184,157 Jones 1 Dec. 19, 1939 2,184,159 Stockbarger etal Dec. 19, 1939 2,193,606 1 Ulrey Mar. 12, 1940 2,454,411 Stoate Nov. 23, 1948 15 2,481,863 Owens Sept. 13, 1949 OTHER REFERENCES Portable Meters for the Measurement of Light and UV Energy, Luckiesh et al., G. E. Review, April 1941, pp. 217- 20 221.

Claims

1. THE METHOD OF INSPECTING THE INTERIOR CYLINDRICAL WALL SURFACE OF AN OPEN MOUTH CONTAINER WHICH COMPRISES PROJECTING A BEAM OF RADIATION FROM A SOURCE OF RADIANT ENERGY, DIRECTING THE BEAM THROUGH THE OPEN MOUTH OF THE CONTAINER, FOCUSING THE BEAM TO A SMALL SPOT ON THE SAID SURFACE, ROTATING THE CONTAINER ABOUT ITS AXIS AND SIMULTANEOUSLY CAUSING A RELATIVE MOVEMENT OF THE SAID SPOT AND THE CONTAINER IN A DIRECTION PARALLEL WITH SAID AXIS AND THEREBY SCANNING THE SURFACE WITH SAID SPOT, AND CAUSING A FLAW AT SAID SURFACE TO REFLECT THE RADIATION AND DIRECT IT TO A PHOTOELECTRIC CELL SENSITIVE TO SUCH RADIATION AND THERE-