Method for monitoring proper fastening of an article of assembly at more than one location

• US 7,062,831 B2
• Filed: 02/27/2004
• Issued: 06/20/2006
• Est. Priority Date: 11/19/2001
• Status: Expired

• Current Assignee: Wildcat Licensing WI LLC (Wildcat Licensing LLC)
• Original Assignee: Lms-Walt, Inc.
• Inventors: Walt, II, Michael A., Walt, Samuel A.
• Primary Examiner(s): COZART, JERMIE E
• Application Number:
  US10/789,307
• Publication Number:
  US 20040163227A1
• Time in Patent Office: 844 Days
• Field of Search: 294/070.1, 294/070.2, 294/070.5, 294/070.9, 294/071, 295/25, 295/250.1, 295/251.1, 297/07, 297/08, 297/09, 297/12, 297/14, 297/20, 297/21, 297/87, 297/95, 298/22, 298/24, 292/435, 292/70, 292/40, 470/1, 470/2, 738/620.8, 738/622.1, 738/622.3, 173/5, 173/6, 173/180, 173/81
• US Class Current: 29/407.02
• CPC Class Codes: B23P 19/066 by electrical means
• CPC Class Codes: B25B 23/14 Arrangement of torque limiters or torque indicators in wrenches or screwdrivers couplings for transmitting rotation or clutches F16D; devices for measuring torque per se G01L
• CPC Class Codes: B25H 1/0021 Stands, supports or guiding devices for positioning portable tools or for securing them to the work B23B41/00 takes precedence
• CPC Class Codes: B25H 1/0028 Tool balancers
• CPC Class Codes: G05B 2219/37459 Reference on workpiece, moving workpiece moves reference point
• CPC Class Codes: G05B 2219/37555 Camera detects orientation, position workpiece, points of workpiece
• CPC Class Codes: G05B 2219/45022 Auto seat, dentist chair, roll wheel chair
• CPC Class Codes: Y10T 29/49719 Seal or element thereof
• CPC Class Codes: Y10T 29/49766 torquing threaded assemblage or determining torque herein
• CPC Class Codes: Y10T 29/49769 Using optical instrument [excludes mere human eyeballing]
• CPC Class Codes: Y10T 29/49771 Quantitative measuring or gauging
• CPC Class Codes: Y10T 29/4978 Assisting assembly or disassembly
• CPC Class Codes: Y10T 29/49947 by applying separate fastener
• CPC Class Codes: Y10T 29/5303 Responsive to condition of work or product
• CPC Class Codes: Y10T 29/53039 with control means energized in response to activator stimulated by condition sensor
• CPC Class Codes: Y10T 29/53052 including position sensor
• CPC Class Codes: Y10T 29/53074 with means to fasten by elastic joining
• CPC Class Codes: Y10T 29/53087 with signal, scale, illuminator, or optical viewer
• CPC Class Codes: Y10T 29/53091 for work-holder for assembly or disassembly
• CPC Class Codes: Y10T 29/53383 and means to fasten work parts together
• CPC Class Codes: Y10T 29/53417 : Means to fasten work parts together
• CPC Class Codes: Y10T 29/53548 : and work carrying vehicle

Abstract

A more reliable and fool-proof method and apparatus for assembling an article of assembly (e.g. with predetermined screw torque requirements) in which the article of assembly has multiple fastening locations. The method comprises holding the article of assembly fixed while providing at least two different types of targets fixed relative to the article of assembly that correspond to the individual fastening locations. Fasteners are fastened into the article of assembly at the fastening locations. When fastening is occurring at one of the fastening locations, one of the targets is being sensed. Based on the target sensed, a target output is generated that differentiates between different types of targets thereby indicating fastening location of the fastening tool. The electronic target output is used for electronic control such as for stopping a conveyor to keep the article of assembly at an assembly station until the fastening operations have been completed.

Claims

1. A method for assembling an article of assembly, the article of assembly having a plurality of fastening locations including first and second fastening locations in spaced apart relation, comprising:

holding the article of assembly in a predetermined position;

providing a plurality of targets including at least a first target fixed relative to the article of assembly corresponding to the first fastening location of the article of assembly and a second target fixed relative to the article of assembly corresponding to the second fastening location, the second target having a different characteristic than the first target;

manually fastening fasteners into the article of assembly at the first and second fastening locations; and

sensing the first and second targets when said fastening is occurring at the first and second locations, respectively, and generating an electronic target output based upon said sensing that differentiates between the first and second targets thereby indicating when a fastening tool is in either of the first and second fastening locations.

2. The method of claim 1 further comprising conveying the article of assembly through an assembly station.

3. The method of claim 2 further comprising:

intermittently stopping the article of assembly at the assembly station for said fastening; and

monitoring the location of said fastening to ensure proper fastening of fasteners at the fastening locations.

4. The method of claim 3 further comprising:

maintaining the fixture at the assembly station and not releasing the fixture for further conveying out of the assembly station until the fastening tool has properly fastened fasteners into the article of assembly at the first and second fastening locations.

5. The method of claim 4, wherein the fasteners are threaded fasteners, further comprising:

measuring torque applied to the fasteners;

electronically indicating measured torque applied to the fasteners at at least one of the fastening locations;

determining the location of said fastening that corresponds to the indicating of measured torque;

electronically comparing measured torque with predetermined torque values for the at least one of the fastening locations; and

providing an output indicating whether the predetermined torque values for at least one of the fastening locations have been reached.

6. The method of claim 5, further comprising:

releasing the article of assembly and conveying the article of assembly out of the assembly station when the predetermined torque values have been reached.

7. The method of claim 1, further comprising:

monitoring a sequence of said fastening;

electronically comparing the monitored sequence with a predetermined sequence of fastening among the fastening locations; and

providing a sequence output indicating whether the predetermined sequence has been achieved.

8. The method of claim 2 further comprising transporting the articles of assembly through the assembly station substantially without stopping on a continuous basis.

9. The method of claim 8, further comprising:

providing at least two types of first and second targets, each different type corresponding to one of the articles of assembly;

generating said target output that differentiates between the at least two types of first and second targets; and

electronically determining the article of assembly subject to said fastening by differentiating between the different types of the first and second targets.

10. The method of claim 8 wherein the assembly station has an input location receiving fixtures from an upstream station and an output location delivering fixtures to a downstream station, wherein said fastening is conducted in a range between the input location and the output location, further comprising:

electronically sensing when articles of assembly are exiting the assembly station and providing a fixture position output indicating when fixtures have exited the assembly station through the output location;

electronically determining whether said fastening has been properly conducted on each article of assembly exiting the assembly station; and

outputting an electronic alarm signal when one of the articles of assembly has exited the assembly station without proper fastening at the first and second fastening locations.

11. The method of claim 10, further comprising temporarily stopping the conveying of the articles of assembly in response to the electronic alarm signal so corrective action may be performed on the article of assembly.

12. The method of claim 10, wherein the fasteners are threaded fasteners, wherein said proper fastening comprises:

measuring torque applied to the fasteners;

electronically indicating measured torque applied to the fasteners at at least one of the fastening locations;

determining the location of said fastening that corresponds to the indicating of measured torque;

electronically comparing measured torque with predetermined torque values for the at least one of the fastening locations; and

providing an output indicating whether the predetermined torque values for at least one of the fastening locations have been reached.

13. The method of claim 10 wherein said proper fastening comprises:

monitoring a sequence of said fastening;

electronically comparing the monitored sequence with a predetermined sequence of fastening among the first and second fastening locations; and

providing a sequence output indicating whether the predetermined sequence has been achieved.

14. The method of claim 10 further comprising:

assigning adjacent articles of assembly different types of the first and second targets for purposes of differentiation according to a predetermined fixture sequence;

determining the article of assembly subject to fastening operations based upon the predetermined sequence.

15. The method of claim 1 wherein said sensing is accomplished with a machine vision camera and wherein the targets have different visual characteristics, further comprising electronically differentiating between the different visual characteristics contained in the electronic target output to determine the location of the fastening tool.

16. The method of claim 15 wherein the targets are selected from the group consisting of geometric shapes, colors and alphanumeric characters.

17. The method of claim 2 wherein said sensing is accomplished with a laser and laser sensing device, said fastening being accomplished with the fastening tool movable in a plane spaced from the article of assembly to selectively position the fastening tool at the fastening locations, the laser and laser sensing device being movable with the fastening tool in said plane, the targets comprising reflective material spaced at different distances perpendicular to said plane.

18. The method of claim 17 wherein the fastening tool plunges along a fastening axis perpendicular to said plane, the laser and laser sensing device remaining stationary during plunging of the fastening tool.

19. The method of claim 18 wherein the article of assembly is carried by a conveyor, the fastening tool being movable horizontally relative to the conveyor, the laser and laser sensing device being restricted to horizontal movement along a horizontal axis along with the fastening tool, further comprising a reflective panel extending in the horizontal axis in reflective communication with the laser and laser sensing device with a reflective surface aligned at an oblique angle relative to said plane providing the targets.

20. The method of claim 1 wherein the article of assembly comprises an automotive seat comprised of at least two parts, the fasteners comprising threaded fasteners for fastening the at least two parts together.

21. The method of claim 1 further comprising:

enabling the fastening tool when one of the targets is sensed; and

disabling the fastening tool when none of the targets are sensed.

22. A method for assembling an article of assembly, the article of assembly having a plurality of fastening locations including first and second fastening locations in spaced apart relation, comprising:

holding the article of assembly in a predetermined position;

manually fastening fasteners into the article of assembly using a fastening tool at the first and second fastening locations according to a predetermined fastening sequence;

sensing the position of the fastening tool;

electronically comparing the sensed position of the fastening tool with a predetermined sequence of fastening among the first and second fastening locations; and

providing a sequence output indicating whether the predetermined sequence has been achieved.

23. The method of claim 22, wherein the article of assembly comprises a vehicle seat.

24. The method of claim 22, further comprising enabling the fastening tool when the fastening tool is at one of the first and second locations and a predetermined fastening sequence is followed, and disabling the fastening tool when the predetermined fastening sequence is not followed.

25. The method of claim 24, further comprising disabling the fastening tool when not at a fastening location.

26. The method of claim 24, further comprising monitoring torque applied during said manual fastening, providing an electronic torque output indicating whether at least one predetermined torque value has been reached.

27. The method of claim 26, enabling the fastening tool when the fastening tool is at one of the first and second locations and a predetermined fastening sequence is followed, and disabling the fastening tool when the predetermined fastening sequence is not followed.

28. The method of claim 27, further comprising disabling the fastening tool when a predetermined torque value is not reached for one of the fastening locations in the predetermined sequence and the fastening tool is at a fastening location other than said one of the fastening locations.

29. The method of claim 22, wherein said sensing comprises sensing targets including first and second targets arranged in relation to the first and second fastening locations, the first and second targets being sensed when said fastening is occurring at the first and second fastening locations, respectively;

and generating an electronic target output based upon said sensing that differentiates between the first and second targets thereby indicating when the fastening tool is in either of the first and second fastening locations.

30. The method of claim 29, wherein said sensing is conducted with one of a machine vision camera and a laser sensing device.