Methods and apparatus for backgaging and sensor-based control of bending operation

• US 5,987,958 A
• Filed: 11/28/1997
• Issued: 11/23/1999
• Est. Priority Date: 11/09/1994
• Status: Expired due to Fees

• Current Assignee: Amada America, Inc. (Amada Company Limited), Amada Company Limited
• Original Assignee: Amada America, Inc. (Amada Company Limited), Amada Company Limited
• Inventors: Sturgas, Robert H. Jr., Hazama, Kensuke, Bourne, David Alan, Murray, Anne Marie, Moore, Richard M. Jr., Elkins, Kerry L.
• Primary Examiner(s): Larson, Lowell A.
• Assistant Examiner(s): TOLAN, EDWARD THOMAS
• Application Number:
  US08/980,301
• Time in Patent Office: 725 Days
• Field of Search: 72/16.8, 72/16.9, 72/17.3, 72/18.5, 72/18.6, 72/18.8, 72/19.4, 72/19.6, 72/31.1, 72/31.11, 72/31.12, 72/37, 72/389.1, 72/389.3 , 72/389.4, 72/420, 72/421, 72/422, 72/441, 72/443, 72/446, 72/702, 483/14, 483/15, 33/263, 33/282, 33/285, 33/286, 364/468.21, 364/469.03, 364/474.07
• US Class Current: 72/422
• CPC Class Codes: B21D 5/002 Positioning devices
• CPC Class Codes: B21D 5/02 on press brakes without making use of clamping means
• CPC Class Codes: B23Q 15/22 Control or regulation of position of tool or workpiece
• CPC Class Codes: B23Q 15/225 in feed control, i.e. approaching of tool or work in successive decreasing velocity steps
• CPC Class Codes: B23Q 17/225 of a workpiece relative to the tool-axis
• CPC Class Codes: B23Q 3/186 Aligning devices
• CPC Class Codes: B25J 9/1679 characterised by the tasks executed
• CPC Class Codes: G05B 2219/31103 Configure parameters of controlled devices
• CPC Class Codes: G05B 2219/31326 Database to manage communication networks
• CPC Class Codes: G05B 2219/37571 Camera detecting reflected light from laser
• CPC Class Codes: G05B 2219/39508 Reorientation of object, orient, regrasp object
• CPC Class Codes: G05B 2219/39528 Measuring, gripping force sensor build into hand
• CPC Class Codes: G05B 2219/39529 Force, torque sensor in wrist, end effector
• CPC Class Codes: G05B 2219/39532 Gripping force sensor build into finger
• CPC Class Codes: G05B 2219/39542 Plan grasp points, grip matrix and initial grasp force
• CPC Class Codes: G05B 2219/40054 Supply sheet to bending machine
• CPC Class Codes: G05B 2219/45143 Press-brake, bending machine
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

Several methods and subsystems are disclosed for aligning a workpiece as it is being loaded into a die space of a bending apparatus, and for performing sensor-based control of a robot as it moves a workpiece from one location to another within a bending apparatus environment. A backgaging mechanism is provided with finger gaging mechanisms having force sensors for sensing forces in directions perpendicular to and parallel to a die. In addition, a robot gripper sensor is provided for sensing either or both of shear forces and normal forces created by movement of a workpiece being held by the gripper. Several sensor-based control modules are disclosed, including a bend-following control module, a speed control module, a module for actively damping vibrations in a workpiece, a module for controlling active compliance/contact between a workpiece and an obstacle, a module for performing a guarded move to intentionally bring a workpiece into contact with an obstacle, and a module for detecting unintentional impacts between a workpiece and an obstacle. Several droop sensing methods and systems are also disclosed, including methods for performing droop sensing and compensation with the use of a vision-based droop sensor, a compound break-beam droop sensor, and a single break-beam droop sensor. In addition, an angle sensor is disclosed, along with a springback control method utilizing the disclosed angle sensor.

Claims

1. A system for loading a workpiece into a die space of a bending apparatus, said system comprising:

a measuring system that measures an amount of droop offset of a leading edge of said workpiece before said workpiece is loaded into said die space;

a system that moves said workpiece in an upward direction by the measured droop offset; and

a loading system that loads said workpiece into said die space.

2. The apparatus according to claim 1, wherein said measuring system comprises a back-lit vision-based droop sensor.

3. The apparatus according to claim 1, wherein said measuring system comprises a vision-based droop sensor.

4. The apparatus according to claim 1, wherein said measuring system comprises a mechanism for sensing when each of a plurality of light beams have been intersected by said workpiece as said workpiece is moved toward said die space.

5. The apparatus according to claim 1, wherein said measuring system comprises a single break-beam detecting mechanism for detecting when a single light beam has been broken by movement of said workpiece toward said die space.

6. The system of claim 1, said moving system moves said workpiece without rotation.

7. Apparatus for executing a bend on a malleable sheet workpiece with bend-following, said apparatus including a bending apparatus, said bending apparatus comprising a die, a tool punch, and a robot gripper for holding said workpiece, said apparatus comprising:

reading means for reading a position value indicative of the relative movement of said die with respect to said tool punch;

calculating means for calculating the location of said gripper as it holds onto said workpiece as a function of the position data read by said reading means;

speed control means for limiting the speed of said relative movement of said die with respect to said tool punch so that said calculated location does not change too rapidly;

means for detecting a force between said workpiece and said robot gripper during execution of said bend;

means for modifying the location calculated by said calculating means based upon the detected force;

robot control means for controlling movement of said robot to correspond to the calculated location; and

determining means for determining if a final bend angle has been reached signifying completion of the bend.

8. An angle sensor for detecting an angle of a flange portion of a workpiece as the flange portion is being bent by a bending apparatus, said angle sensor comprising:

a member having a reflective surface;

a holder that holds said member with said reflective surface against said flange portion of said workpiece;

a light emitter that emits a light beam onto said reflective surface; and

a light detector that detects a position of said light beam as said light beam is reflected by said reflective surface, the detected position being indicative of the angle of said flange portion of said workpiece.

9. An angle sensor for detecting an angle of a flange portion of a workpiece as the flange portion is being bent by a bending apparatus, the angle sensor comprising:

a member having a reflective surface;

a holder that holds the member with the reflective surface against the flange portion of the workpiece;

a light emitter that emits a light beam onto the reflective surface; and

a light detector that detects a position of the light beam as the light beam is reflected by the reflective surface, the detected position being indicative of the angle of the flange portion of the workpiece,

wherein the reflective surface is movable towards and away from the flange portion.

10. An angle sensor for detecting an angle of a flange portion of a workpiece as the flange portion is being bent by a bending apparatus, the angle sensor comprising:

a member having a reflective surface;

an arm for supporting the member, the arm being rotatable about an axis parallel to a bending line to be formed in the workpiece by the bending apparatus;

a light emitter that emits a light beam onto the reflective surface; and

a light detector that detects the position of the light beam as the light beam is reflected by the reflective surface, the detected position being indicative of the angle of the flange portion of the workpiece.