Method and apparatus for bending an elongate workpiece

• US 4,947,666 A
• Filed: 09/16/1988
• Issued: 08/14/1990
• Est. Priority Date: 09/16/1988
• Status: Expired due to Fees

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Trammell, Larry L., Hametner, Albert L.
• Primary Examiner(s): JONES, DAVID B
• Application Number:
  US07/245,455
• Time in Patent Office: 697 Days
• Field of Search: 72/9, 72/10, 72/12, 72/37, 72/702, 72/34, 29/407
• US Class Current: 72/37
• CPC Class Codes: B21D 5/004 with program control
• CPC Class Codes: G05B 19/401 characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes G05B19/19 takes precedence
• CPC Class Codes: G05B 19/408 characterised by data handling or data format, e.g. reading, buffering or conversion of data
• CPC Class Codes: G05B 2219/37403 Bending, springback angle
• CPC Class Codes: G05B 2219/37572 Camera, tv, vision
• CPC Class Codes: G05B 2219/45143 Press-brake, bending machine
• CPC Class Codes: G05B 2219/50063 Probe, measure, verify workpiece, feedback measured values
• CPC Class Codes: Y10S 72/702 Overbending to compensate for springback
• CPC Class Codes: Y10T 29/49769 Using optical instrument [excludes mere human eyeballing]

Abstract

Apparatus for bending an elongate workpiece to a desired configuration includes a memory for storing information representative of the desired configuration and information representative of bending operations to be performed by a bending machine. A position sensor is used to scan a workpiece that has been bent using the bending machine, and thereby generate information representative of the actual configuration of the workpiece. The information representative of the actual configuration of the workpiece is compared with the information representative of the desired configuration and, in the event that there is a difference between the actual configuration and the desired configuration, and the difference is beyond a predetermined tolerance, the information representative of bending operations is modified in a manner such as to reduce the difference.

Claims

1. Apparatus for bending an elongate workpiece to a desired configuration, comprising:

an automatic bending machine,

storage means for storing information representative of the desired configuration and information representative of bending operations to be performed by the bending machine in order to bend a workpiece to the desired configuration,

data collection means for automatically scanning a workpiece that has been bent using the automatic bending machine and generating information representative of the actual configuration of the bent workpice, said data collection means comprising position sensor means for sensing the position of a surface element of the workpiece along an axis that is stationary relative to the position sensor means, and transport means for transporting the position sensor means in directions along three mutually perpendicular axes, and

comparison means for comparing the information representative of the actual configuration of the bent workpiece with the information representative of the desired configuration and, in the event that there is a difference beyond a predetermined tolerance, modifying the information representative of bending operations in a manner such as to reduce the difference.

2. Apparatus according to claim 1, comprising control means for controlling the data collection means to scan the workpiece in at least one scanning stage by moving the position sensor means along all three axes.

3. Apparatus according to claim 1, comprising control means for controlling the data collection means to scan the workpiece in at least a first inspection stage and a second inspection stage, and for using information collected by the data collection means during the first inspection stage and the information representative of the desired configuration to define an inspection path to be followed by the position sensor means during the second inspection stage.

4. Apparatus according to claim 3, wherein the transport means are responsive to the control means to move the position sensor means along only one axis during the first inspection stage and to allow movement of the position sensor means along all three axes during the second inspection stage.

5. Apparatus according to claim 3, wherein the control means scan the workpiece at a first density in the first inspection stage and at a second density in the second inspection stage, the second density being greater than the first density.

6. Apparatus for bending an elongate workpiece to a desired configuration, comprising:

an automatic bending machine,

storage means for storing information representative of the desired configuration and information representative of bending operations to be performed by the bending machine in order to bend a workpiece to the desired configuration,

reference means for receiving a workpiece that has been bent using the automatic bending machine and supporting it in a location that is fixed relative to first, second and third mutually-perpendicular axes,

data collection means for automatically scanning a bent workpice received by the reference means and generating information representative of the actual configuration of the bent workpice, said data collection means comprising an optical scanner assembly for emitting light towards a reference plane defined by the first and second axes and receiving light, and means for generating a signal representative of the position, relative to the reference plane, of a surface from which light received by the optical scanner assembly has been reflected, and transport means for moving the scanner assembly relative to the reference means in a direction along the first axis, and

comparison means for comparing the information representative of the actual configuration of the bent workpiece with the information representative of the desired configuration and, in the event that there is a difference beyond a predetermined tolerance, modifying the information representative of bending operations in a manner such as to reduce the difference.

7. Apparatus according to claim 6, wherein the signal generating means comprise means for generating a first signal representative of the position of said surface relative to the optical scanner assembly and means for generating a second signal representative of the position of the optical scanner assembly relative to the reference plane.

8. Apparatus according to claim 6, wherein the optical scanner assembly comprises at least first and second scan heads, the first scan head being stationary relative to the transport means and the second scan head being movable relative to the transport means in directions along the second axis and along a third axis, which is perpendicular to the first and second axes.

9. Apparatus according to claim 8, comprising control means for causing the first and second scan heads to scan the workpiece at first and second densities respectively, the second density being greater than the first density.

10. Apparatus according to claim 8, wherein the second scan head is movable relative to the transport means by rotation about the third axis.

11. Apparatus according to claim 8, wherein the second scan head comprises at least one laser light source for providing an output light beam, a galvanometer for reflecting the light beam into a beam plane that intersects the reference plane and cyclically deflecting the beam within the beam plane, and at least one video camera having an optical axis that intersects the beam plane.

12. Apparatus according to claim 6 wherein the optical scanner assembly comprises at least one scan head that comprises a laser light source for providing an output light beam, a galvanometer for reflecting the light beam into a beam plane that intersects the reference plane and for cyclically deflecting the beam within the beam plane, and a video camera having an optical axis that intersects the beam plane.

13. A method of producing an elongate workpiece that has been bent to a desired configuration, comprising:

(a) bending a workpiece using a sequence of bend instructions,

(b) carrying out a first data collection and generating first information representative of the actual configuration of the workpiece,

(c) comparing the first information with information representative of the desired configuration,

(d) using the result of the comparison to estimate the location and orientation of the workpiece and determine an optimum path for scanning the workpiece,

(e) using a position sensor to carry out a second data collection, by transporting the position sensor along the optimum path, and generate second information representative of the actual configuration of the first workpiece,

(f) comparing the second information with the information representative of the desired configuration and, if the comparison indicates that the workpiece conforms to the desired configuration within a predetermined tolerance, bending at least one additional workpiece using said sequence of bend instructions, and otherwise adjusting the bend instructions.

14. A method according to claim 13, comprising bending a second workpiece using the adjusted bend instructions, and repeating steps (b)-(f).

15. A method according to claim 13, wherein step (b) comprises optically scanning the workpiece.

16. A method according to claim 13, wherein step (b) comprises placing the workpiece at an arbitrary location within an inspection volume and optically scanning the workpiece by translating an optical scanner assembly in a predetermined direction along an axis that is fixed relative to the inspection volume.

17. A method according to claim 16, comprising, before step (b), optically scanning the inspection volume in order to estimate the location of the workpice in the inspection volume.

18. A method according to claim 13, wherein the optimum path is defined such that the position sensor remains at a substantially constant distance from the workpiece.

19. A method according to claim 13, wherein the position sensor is movable along three mutually perpendicular axes, and the optimum path is defined such that the position sensor remains at a substantially constant distance from the workpiece along one of said axes.