Tire inspection apparatus

• US 3,918,816 A
• Filed: 04/22/1974
• Issued: 11/11/1975
• Est. Priority Date: 04/22/1974
• Status: Expired due to Term

• Current Assignee: Techmet Company
• Original Assignee: Donald L. Cullen, George B. Foster
• Inventors: Foster, George B., Cullen, Donald L.
• Primary Examiner(s): McGraw, Vincent P.
• Assistant Examiner(s): Godwin, Paul K.
• Application Number:
  US05/463,147
• Time in Patent Office: 568 Days
• Field of Search: 356/4,156,160,167 331/DIG.1 73/432L,146
• US Class Current: 356/602
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures

Abstract

There is disclosed a method and apparatus for rapid and convenient dimensional inspection of a tire. The method involves mounting the tire for rotation and impinging on its tread surface, a laser beam, analyzing the backscattered radiation to determine the position in space of the point of impingement and selectably scanning or positioning the laser to measure various positions on the tire surface. The apparatus includes the laser device, a mounting unit for the tire to be inspected and another mounting unit for the laser gauge. The first mounting unit permits rotation or angular indexing of the tire. The second mounting unit permits four separate gauge motions: radial or circular scan across the tread surface, lateral scan across the tread surface, rotation of the plane containing the laser beam and the backscattered beam and spacing normal to the axis of tire rotation. The former two motions are motor controlled, the latter two are manually controlled.

Claims

1. A method for non-destructively inspecting the geometry of a tire comprising the steps of:

mounting a tire to be inspected for rotation about its axis, transmitting a narrow energy beam through the atmosphere for impingement on a selected portion of the tire surface;

recovering a portion of said beam returning from the point of impingement;

analyzing said recovered beam portion to develop an electrical signal analog representative of the location in space with respect to a reference location of a selected portion of the tire surface for a particular rotation position;

controllably selecting the measurement location; and

controllably rotating said tire to allow inspection at any location on the tire surface.

2. A method as described in claim 1 further comprising selecting a series of inspection locations on the tire tread surface along the tire axis, rotating said tire through a complete revolution for each such axial position and developing a plurality of electrical signal analogs during each revolution.

3. A method as described in claim 2 further comprising sensing the angular position as said tire rotates and developing said electical signal analogs for predetermined angles of rotation.

4. A method as defined in claim 2 further comprising producing a visual plot of the tread profile from the succession of electrical signal analogs for at least one of said revolutions.

5. A method as defined in claim 2 further including generating a signal analog of the difference between the first signal analogs for the axial position corresponding to a tread groove and to the adjacent tread rib to produce a measure of the tread thickness.

6. A method as defined in claim 1 further comprising selecting a series of inspection angles around the circumference of said tire, rotating said tire to each of said measurement angles in succession and developing a series of said electrical signal analogs for selected portions of said tire surface in a plane including the tire axis for each insPection angle.

7. A method as defined in claim 6 wherein said signal analogs are developed at a plurality of spaced points on a line parallel to the tire axis for each inspection angle.

8. A method as defined in claim 6 wherein said signal analogs are developed at a plurality of spaced points on an arc lying in each of said planes.

9. A method as defined in claim 8 wherein each of said arcs lies on the circle defined by the tire tread radius.

10. A method as defined in claim 6 further comprising producing a visual plot of the tread profile from the succession of electrical signal analogs for at least one of said inspection angles.

11. A method as defined in claim 6 further comprising generating an electrical signal analog of the difference between the first signal analog corresponding to a tread groove and to the adjacent tread rib to produce a measure of the tread thickness.

12. Apparatus as defined in claim 1 wherein said energy beam is a light beam.

13. A method of non-destructively inspecting the geometry of a tire comprising the steps of mounting a tire to be inspected, adjustably positioning a measuring device including a laser and means for analyzing the back scattered laser light to determine the location in space of a point of impingement of a laser beam on the tire surface, adjusting the relative position of the tire under inspection and said measuring device and generating an electrical signal analog of the location in space of the tire surface for each of a succession of said relative positions.

14. A method as defined in claim 13 further comprising producing a visual plot of the tire tread profile from said succession of electrical signal analog.

15. A method as defined in claim 13 further including generating a signal analog of the difference between the first signal analogs for a relative position corresponding to a tread groove and to the adjacent tread rib to produce a measure of the tread thickness.

16. A method for non-destructively inspecting the geometry of a tire comprising the steps of:

mounting a tire to be inspected about its axis, developing an electrical signal analog representative of the location in space with respect to a reference location of a selected portion of the tire surface for a particular rotational position;

controllably selecting the measurement location and controllably rotating said tire to allow inspection at any location on the tire surface;

said step of developing said electrical signal analog comprising impinging a laser beam on a selected portion of the tire surface, recovering a portion of the backscattered light from the point of impingement, analyzing said recovered light to determine said location in space and generating said electrical signal pursuant to said analysis.

17. Apparatus for non-destructive inspection of the dimensions of a tire comprising:

a first mounting fixture for rotatably supporting a tire to be inspected;

a gauging system including means for transmitting a narrow beam of energy through the atmosphere for impingement on the surface of a tire mounted in said fixture, means to recover energy returning from said point of impingement, and means for developing an electrical signal representative of said point of impingement responsive to said recovered energy;

a second mounting fixture for the measuring portion of said gauging system;

drive means for moving said second mounting fixture to select the position on the tire at which the measurement is made; and

means for controlling the rotation of said tire mounting fixture.

18. Apparatus as described in claim 17 wherein said means for controlling the rotation of the tire mounting fixture comprises a motor, and position encoder means for generating electrical signals representing the angle of rotation of said mounting fixture.

19. Apparatus as defined in claim 17 wherein said gauging system includes means to generate a laser beam, means to direct said laser beam for impingement on the surface of the tiRe under inspection, means to recover a portion of the backscattered radiation from the point of impingement, and means for analyzing the pattern of said backscattered radiation and for generating an electrical signal correlating the position of the tire surface with said backscattered radiation pattern.

20. Apparatus as defined in claim 17 wherein said gauging means comprises means for generating a laser beam, means for directing said laser beam for impingement on the surface of the tire under inspection, optical means for observing light backscattered from said point of impingement from two different aspects relative to said laser beam, means to direct recovered backscattered light onto an image plane in the form of two light spots, the spacing of which is a function of the position in space of the tire surface, image conversion means responsive to said two light spots in said image plane to generate an electrical signal representative of the spot spacing.

21. Apparatus for non-destructive inspection of the dimensions of a tire comprising means for rotatably mounting a tire to be inspected, a measuring device, said measuring device including means for generating a laser beam, means for directing said laser beam for impingement on the surface of the tire under inspection, means for recovering a portion of the backscattered radiation from said point of impingement, and means to analyze the pattern of said backscattered radiation and to generate an electrical signal correlating the position of the point of impingement in space with said backscattered radiation pattern;

mounting means for said measuring device;

means for adjustably positioning said measuring device relative to the tire under inspection to select the point of impingement of said laser beam on the tire surface; and

means for establishing controlled relative motion between said measuring device and said tire to allow selected inspection of the entire tread surface of said tire.

22. Apparatus for non-destructive inspection of the dimensions of a tire comprising:

a first mounting fixture for rotatably supporting a tire to be inspected;

a gauging system including means for measuring the location in space of a selected portion of the surface of a tire mounted in said fixture, and means for developing an electrical signal representative of said measured location;

a second mounting fixture for the measuring portion of said gauging system;

drive means for moving said second mounting fixture to select the position relative to the tire at which the measurement is made;

means for controlling the rotation of said tire mounting fixture;

said second mounting fixture comprising an elongated beam, pivot means for rotatably supporting said beam at one end; and

said drive means including means for rotating said beam about said pivot, and position sensing means to provide electrical signal indication of the angular position of said member.

23. Apparatus as defined in claim 22 wherein the said means for rotating said beam comprises a threaded shaft and follower means mounted on said shaft, said follower means being connected to said beam to effect motion thereof as said shaft rotates.

24. Apparatus as defined in claim 23 including a slotted member secured to said beam, said follower including a first portion engaging said threaded shaft and a second portion engaging with said slot.

25. Apparatus as defined in claim 24 wherein said slotted member is so disposed that the slot therein lies parallel to the axis of elongation of said beam.

26. Apparatus as set forth in claim 23 further including mounting means for said follower, pivotally mounted to allow rotation thereof relative to said beam as said threaded shaft rotates.

27. Apparatus as set forth in claim 22 wherein said second mounting fixture further includes first carriage means, means for adjustably positioning said first carriage means along the length of said elongated beam, second carriage means, and support means on said first carriage means pErmitting adjustable positioning of said second carriage means;

and wherein said drive means further comprises means for positioning said second carriage means on its support means.

28. Apparatus as set forth in claim 27 wherein said adjustable positioning means for said first carriage comprises a pair of elongated shaft members mounted in spaced parallel relationship with the axis of elongation of said beam, and slide bushing means mounted on said first carriage means and coupled to said shafts for sliding motion thereon.

29. Apparatus as set forth in claim 27 wherein said adjustable positioning means for said second carriage means comprises a pair of support shafts mounted in spaced parallel relationship normal to the axis of elongation of said beam and a slide bushing means slidably coupling said second carriage means to said support shafts.

30. Apparatus as defined in claim 29 wherein said means for positioning said second carriage means comprises a threaded shaft mounted in spaced parallel relationship with said carriage support shafts and a follower mounted on said second carriage means and coupled to said threaded shaft.

31. Apparatus as defined in claim 27 wherein said second mounting fixture further includes gauge support means fixedly mounted on said second carriage means and including means for adjustably positioning thereon the measuring portion of said gauging system.

32. Apparatus as defined in claim 30 wherein said gauging means is characterized by an axis of elongation extending generally toward the tread surface of the tire under inspection, and wherein said gauge support means includes bearing means cooperating with a complementary portion of said gauge means to support said gauge means for angularly adjustable positioning about said axis of elongation.