High resolution electronic automatic imaging and inspecting system

• US 4,583,854 A
• Filed: 07/13/1983
• Issued: 04/22/1986
• Est. Priority Date: 07/15/1982
• Status: Expired due to Fees

• Current Assignee: Carboloy Incorporated
• Original Assignee: General Electric Company
• Inventors: Lozar, Boris
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Saitta, Thomas C.
• Application Number:
  US06/513,486
• Time in Patent Office: 1,014 Days
• Field of Search: 356/237, 356/69, 356/445, 73/104, 250/224, 350/523, 350/612, 350/618, 350/622
• US Class Current: 356/237.1
• CPC Class Codes: G01B 11/022 by means of tv-camera scanning
• CPC Class Codes: G01B 11/2433 for measuring outlines by shadow casting
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination

Abstract

In a high resolution optical electronic imaging system to detect defects and dimensional changes in articles of manufacture for example, metal cutting tool inserts, a convergent blade-shaped laser light beam emitted by a laser passes through a focusing optical system and is then directed to a revolving head which contains a mirror system. The focusing and mirror system scans the apex of the blade beam along the cutting edges of an insert so that edge defects and dimensional changes cause reflection and refraction of the laser beam. High resolution and contrast television camera and optic system receives the reflections and refractions and creates an image of the device with sharply contrasted defects.

Claims

1. An imaging system for dimensional inspection and edge defect detection of metal inserts for machining operations having a pair of parallel surfaces and a planar edge surface defining a cutting edge therewith comprising in combination:

(a) support means supporting an insert in a darkened environment;

(b) optical means to project a single blade shaped light beam angularly across said insert cutting edge, said beam having a minimum width and corresponding maximum intensity at an area coincident with said cutting edge;

(c) said optical means includes a laser light source and a lens arrangement to provide a single triangular shaped beam which coverges in the direction of the insert so that the apex of the beam falls essentially on a point on said cutting edge;

(d) said optical means including a revolving head and revolving means therefor to move said light beam along said cutting edge said insert so that edge defects become a source of perturbations of the single blade shaped beam to provide light scattering and diffusion; and

(e) electronic detection means to record and display said light scattering as a measurement of said defect or a dimensional change of said insert.

2. The invention as recited in claim 1 wherein said electronic detection means is an imaging system which creates an enlarged image of said insert based on said light scattering or diffusing and a computer means to provide dimensional inspection, defect counting and insert classification.

3. An imaging system according to claim 1 wherein said optical means includes a revolving head which is equipped with a plurality of mirrors positioned to make said single blade-shaped beam impinge against a cutting edge of an insert with a given inclination angle corresponding to an angle between said blade-shaped beam and a supporting plane of said insert, said mirrors transforming said light beam into the blade-shaped beam impinging against the said cutting edge of the insert, through two reflections having angles which are respectively, the first being the sum of 90°

and the inclination angle of the blad-shaped beam in respect to said supporting plane of the insert and the second being the double of said inclination angle.

4. An imaging system according to claim 3 characterized in that the inclination angle between the said blade-shaped beam and said supporting plane is selected equal to 30°

in a manner that the reflection angles of the said two mirrors are 120° and

60°

respectively.

5. The invention as recited in claim 1 wherein said revolving head and revolving means therefor includes a mirror system to direct said light beam at a slight angle of incidence along peripheral cutting edges of said insert, said head being co-axially spaced from said insert and axially adjustable thereto.

6. An imaging system according to claim 5 wherein said optical means includes a focusing system comprising a lens system, the distance between said lens system and the cutting edge of the insert fixed, in a manner so that, when a polygon insert is being inspected, the distance between the periphery of the insert and revolving head will change in a given value in one direction while the distance between the lens system and the revolving head will change in an equal value in the opposite direction.

7. An imaging system according to claim 6 characterized in that the distance between the lens system and the said revolving head and the distance between said revolving head and the said supporting plane are changed in such a manner that a change in "h", the axial distance between the revolving head and the supporting plane, will correspond a change "h/sinα

" of the distance between the lens system and revolving head, wherein "α

" is the inclination angle of the blade-shaped ray in respect to the supporting plane.

8. An imaging system of claim 6 characterized in that an angle "α

", the inclination angle of the blade-shaped ray in respect to the supporting plane, is selected equal to 30°

in such a manner that a change in "h", the distance between revolving head and the insert supporting plane, will correspond a change "h" of the distance between revolving head and the insert supporting plane will correspond a change "2h" between the system and revolving head.

9. An imaging system according to claim 6 wherein a hollow sleeve incorporates the lens system and is equipped with two threads having respectively opposite directions and different pitches, one of said threads engaging a complementary thread supporting said rotary head and the other of said threads engaging a complementary thread on a co-axial sleeve so that rotation of said co-axial sleeve moves the lens system in one direction and the head to an opposite direction, so that indicating by "f" the pitch of the thread allowing the movement of the optical group and by "F" the pitch of the thread allowing the motion of the revolving head the ratio between said pitches is defined by the formula:

space="preserve" listing-type="equation">f=F (1-sinα

)

wherein angle "α

" is the inclination angle of the blade-shaped ray in respect to the supporting palne.

10. An imaging system according to claim 6 characterized in that said distance changes are provided by two racks having tooth pitch ratio equal to the pitch ratio of the threads of claim 9.

11. An imaging system according to claim 6 characterized in that the two distance changes are provided by two stepping motors, having revolution ratio equal to the one mentioned in said claim 9.

12. An imaging system according to claim 6 wherein a hollow sleeve incorporates the lens system and is equipped with two threads having respectively opposite directions and different pitches, one of said threads engaging a complementary thread supporting said rotary head and the other of said threads engaging a complementary thread on a co-axial sleeve so that rotation of said co-axial sleeve moves the lens system in one direction and the head to an opposite direction, so that indicating by "f" the pitch of the thread allowing the movement of the optical group and by "F" the pitch of the thread allowing the motion of the revolving head and wherein an angle "α

", the inclination angle in the blade-shaped ray in respect to the supporting plane, is made equal to 30°

so that the ratio among the pitches of the threads and/or among the distance changes will result f=1/2F.

13. An imaging system for dimensional inspection and edge defect detection of a polygon-shaped body having a pair of parallel opposed surface and edge surfaces comprising:

(a) rotary support plane means adapted to support the polygon-shaped body having a pair of parallel opposed surfaces and edge surfaces, with one parallel surface resting on said support plane;

(b) a pair of leaser beam means laterally disposed from said support plane and at an oblique angle thereto, said laser beam means providing triangular shaped beams directed at an inclined angle to opposite edge surfaces so that the apex of each said beam is substantially coincident with a separate edge of the edge surface to which it is directed; and

the two beams converge concentrically over one of said parallel surfaces;

(c) said beams being refracted by opposed edge surfaces and being oppositely and perpendicularly reflected by said opposed edge surfaces;

(d) means to rotate said rotary support so that reflections and refractions occur around the periphery of said body; and

(e) an electro optical group adapted to receive said reflections and refractions and to thereby identify defects and dimensional changes.

14. The invention as recited in claim 13 wherein said electro optic group comprises a plurality of TV cameras which provide an enlarged image of said insert.

15. The invention as recited in claim 13 wherein said electro optical group includes three T.V. cameras, one of which is positioned coaxial with said insert to receive refractions of said beams which converge between said insert and said camera, and the other two cameras are aligned one each with said oppositely and laterally disposed laser sources to receive perpendicular reflections from the edge surfaces.