Vision system with reflective device for industrial parts

• US 20020125450A1
• Filed: 05/06/2002
• Published: 09/12/2002
• Est. Priority Date: 10/07/1999
• Status: Active Grant

• Current Assignee: Logical Systems, Inc.
• Original Assignee: Logical Systems, Inc.
• Inventors: Gochar, Joseph P. Jr.
• Granted Patent: US 6,784,447 B2
• Time in Patent Office: Days
• US Class Current: 250/559.45
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination
• CPC Class Codes: G01N 21/89 in moving material, e.g. running paper or textiles G01N21/90, G01N21/91, G01N21/94 take precedence
• CPC Class Codes: G01N 21/909 in opaque containers or opaque container parts, e.g. cans, tins, caps, labels
• CPC Class Codes: G01N 21/95 characterised by the material or shape of the object to be examined G01N21/89 - G01N21/91, G01N21/94 take precedence

Abstract

A machine vision inspection system for industrial parts such as plastic molded caps or the like can reliably detect defects at very high inspection rates on the order of 1600 per minute of a variety of cap colors and liners including previously difficult to inspect combinations. Advantageously, the system includes an inclined inspection ramp which provides separation between the caps which are processed through an inspection station to provide accurate imaging of each individual cap without interference from adjacent caps. Further, the inspection station includes a reflective device which provides accurate and reliable imaging of numerous views of caps with a single color to detect and identify defects.

Claims

1. A system for inspecting a work piece, the system comprising:

an inspection platform adapted to support the work piece;

a light source adapted to illuminate the work piece on the inspection platform;

a camera adapted to produce an image of the work piece illuminated by the light source and positioned on the inspection platform;

a reflective device positioned within a field of view of the camera;

wherein the image includes a reflected portion of the work piece which is reflected off of the reflective device;

a processing unit operably coupled to the camera to analyze the image of the work piece generated by the camera with respect to predetermined quality control standards; and

a rejection mechanism operably coupled to the processing unit to receive a control signal from the processing unit, the rejection mechanism being operable to remove the work piece from the platform based on the control signal.

2. The system of claim 1 wherein the reflective device is nonplanar.

3. The system of claim 1 wherein the reflective device is conical.

4. The system of claim 3 wherein the conical reflective device is a truncated cone with a central aperture there through.

5. The system of claim 1 wherein the reflected portion is a 360°

view of the work piece.

6. The system of claim 1 further comprising:

an adjustable mounting mechanism coupled to the reflective device in which a distance from the reflective device to the platform is adjustable.

7. The system of claim 1 further comprising:

an adjustable mounting mechanism coupled to the camera in which a distance from the camera to the platform is adjustable.

8. The system of claim 1 wherein the image includes both a direct portion that is not reflected off of the reflective device and the reflected portion.

9. The system of claim 1 wherein the reflected portion of the image is a view of a portion of the work piece that is not oriented generally orthogonal to a line of sight of the camera.

10. The system of claim 1 for inspecting each of a series of serially fed work pieces in a stream of such work pieces, wherein the platform further comprises:

an inspection ramp inclined downwardly with respect to a horizontal plane and having a top end and a bottom end, each of the work pieces being serially received at the top end and discharged at the bottom end, each of the work pieces separating a distance from the adjacent work pieces and maintaining contact with an upper surface of the inspection ramp as it moves from the top end to the bottom end.

11. The system of claim 10 wherein the upper surface of the inspection ramp is generally planar and stationary.

12. The system of claim 10 further comprising:

a feed conveyor in communication with the top end to serially feed the work pieces each of which is in contact with adjacent work pieces on the feed conveyor; and

a discharge conveyor in communication with the bottom end to receive and discharge each of the work pieces at the bottom end.

13. The system of claim 1 further comprising:

a trigger operably coupled to the camera and positioned relative to the inspection platform to detect a position of the work piece and send a trigger signal to the camera to take an image of the work piece.

14. The system of claim 1 wherein the light source is positioned on a back side of the work piece and opposite from the camera to back light the work piece and at least a portion of the inspection platform is at least translucent to permit light from the light source to pass there through and illuminate the work piece.

15. The system of claim 1 wherein the camera is positioned generally perpendicularly with respect to the inspection platform.

16. The system of claim 1 wherein the image includes an interior portion of the work piece contained within a perimeter of the work piece and the light source illuminates the interior portion.

17. The system of claim 16 wherein the interior portion is not oriented generally orthogonal to a line of sight of the camera.

18. The system of claim 1 wherein the image is produced with only the single camera.

19. The system of claim 1 further comprising:

a viewing cylinder in which the reflective device is mounted.

20. A system for inspecting each of a series of serially fed work pieces in a stream of such work pieces , the system comprising:

an inspection ramp inclined downwardly with respect to a horizontal plane and having a top end and a bottom end, each of the work pieces being serially received at the top end and discharged at the bottom end, each of the work pieces separating a distance from the adjacent work pieces and maintaining contact with an upper surface of the inspection ramp as it moves from the top end to the bottom end, wherein the upper surface of the inspection ramp is generally planar and stationary;

a light source adapted to illuminate the work piece on the inspection platform;

a single camera adapted to produce an image of the work piece illuminated by the light source and positioned on the inspection platform;

wherein the camera is oriented generally perpendicularly with respect to the inspection platform;

wherein the light source is positioned on a back side of the work piece and opposite from the camera to back light the work piece and at least a portion of the inspection ramp is at least translucent to permit light from the light source to pass there through and illuminate the work piece;

a conical reflective device positioned within a field of view of the camera;

wherein the image includes a reflected portion of the work piece which is reflected off of the reflective device and a direct portion that is not reflected off of the reflective device;

wherein the image further includes an interior portion of the work piece contained within a perimeter of the work piece and the light source illuminates the interior portion;

an adjustable mounting mechanism coupled to the reflective device and the camera in which a first distance from the reflective device to the platform is adjustable as well as a second distance from the camera to the platform is adjustable;

a processing unit operably coupled to the camera to analyze the image of the work piece generated by the camera with respect to predetermined quality control standards;

a trigger operably coupled to the camera and positioned relative to the inspection ramp to detect a position of the work piece and send a trigger signal to the camera to take an image of the work piece; and

a rejection mechanism operably coupled to the processing unit to receive a control signal from the processing unit, the rejection mechanism being operable to remove the work piece from the platform based on the control signal.

21. The system of claim 20 further comprising:

a feed conveyor in communication with the top end to serially feed the work pieces each of which is in contact with adjacent work pieces on the feed conveyor; and

a discharge conveyor in communication with the bottom end to receive and discharge each of the work pieces at the bottom end.

22. A method of inspecting a work piece, the method comprising the steps of:

positioning the work piece on an inspection platform;

illuminating the work piece on the inspection platform with a light source;

activating a camera to produce an image of the work piece illuminated by the light source;

reflecting at least a portion of the field of view of the camera so that the image includes the reflected portion of the work piece;

analyzing the image with respect to predetermined quality control standards; and

removing the work piece from the inspection platform in a first direction if the image thereof does not satisfy the predetermined quality control standards and in a second direction if the image does satisfy the predetermined quality control standards.

23. The method of claim 22 wherein the image includes at least an interior portion of the work piece within a perimeter of the work piece.

24. The method of claim 22 wherein the illuminating further comprises back lighting the work piece from a position generally opposite from the camera, at least a portion of the inspection platform is at least translucent to permit passage of light from the light source through the inspection platform to illuminate the work piece.

25. The method of claim 22 wherein the reflecting further comprises:

positioning a reflective device in the field of view of the camera, wherein a shape of the reflective device is selected from the group consisting of non-planar, arcuate and conical shapes.

26. The method of claim 22 wherein each of a series of work pieces is inspected, the method further comprising:

feeding the work pieces to a top end of a downwardly inclined inspection ramp, wherein each of the work pieces is in contact with an adjacent work piece at the top end;

moving each of the work pieces downwardly along the inspection ramp, over the inspection platform and toward a bottom end of the inspection ramp; and

generating a spacing distance on the at the inspection platform between each of the work pieces and adjacent work pieces.

27. The method of claim 26 wherein the moving of the work pieces downwardly along the inspection ramp is accomplished by gravity and the inspection ramp is generally planar and stationary.

28. A method of inspecting each of a series of plastic molded caps each having a liner therein, the method comprising the steps of:

feeding the caps to a top end of a downwardly inclined inspection ramp, wherein each of the caps is in contact with an adjacent cap at the top end;

moving each of the caps downwardly along the inspection ramp, over the inspection platform and toward a bottom end of the inspection ramp;

wherein the moving of the caps downwardly along the inspection ramp is accomplished by gravity and the inspection ramp is generally planar and stationary;

generating a spacing distance on the inspection ramp between each of the caps and adjacent caps;

illuminating the cap on the inspection ramp with a light source;

activating a camera to produce an image of the cap illuminated by the light source;

wherein the illuminating further comprises back lighting the cap from a position generally opposite from the camera, at least a portion of the inspection platform is at least translucent to permit passage of light from the light source through the inspection platform to illuminate the cap;

positioning a reflective device in the field of view of the camera, wherein a shape of the reflective device is selected from the group consisting of non-planar, arcuate and conical shapes;

reflecting at least a portion of the field of view of the camera so that the image includes the reflected portion of the cap;

wherein the image includes at least an interior portion of the cap within a perimeter of the cap;

analyzing the image with respect to predetermined quality control standards; and

removing the cap from the inspection platform in a first direction if the image thereof does not satisfy the predetermined quality control standards and in a second direction if the image does satisfy the predetermined quality control standards.