CLAMP ASSEMBLY INCLUDING PERMANENT MAGNETS AND COILS FOR SELECTIVELY MAGNETIZING AND DEMAGNETIZING THE MAGNETS

• US 20130285399A1
• Filed: 04/30/2012
• Published: 10/31/2013
• Est. Priority Date: 04/30/2012
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology, The Boeing Co.
• Original Assignee: Massachusetts Institute of Technology, The Boeing Co.
• Inventors: Sarh, Branko, Rus, Daniela Lucia, Marchese, Andrew Dominic
• Granted Patent: US 8,912,872 B2
• Time in Patent Office: Days
• US Class Current: 294/65.5
• CPC Class Codes: B21J 15/142 Aerospace structures
• CPC Class Codes: B21J 15/30 Particular elements, e.g. supports; Suspension equipment specially adapted for portable riveters
• CPC Class Codes: B21J 15/42 Special clamping devices for workpieces to be riveted together, e.g. operating through the rivet holes
• CPC Class Codes: B23Q 3/1543 using electromagnets
• CPC Class Codes: B23Q 3/1546 using permanent magnets
• CPC Class Codes: B25B 11/002 Magnetic work holders
• CPC Class Codes: B25B 31/005 for temporarily connecting sheets before or during assembly operations
• CPC Class Codes: B25B 5/145 for plates
• CPC Class Codes: B25J 15/0608 with magnetic holding means
• CPC Class Codes: H01F 7/0226 PM with variable field strength H01F7/0284 takes precedence
• CPC Class Codes: H01F 7/04 Means for releasing the attractive force
• CPC Class Codes: H01F 7/18 Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings
• CPC Class Codes: H01F 7/1805 Circuit arrangements for holding the operation of electromagnets or for holding the armature in attracted position with reduced energising current for holding relay armature in attracted position with reduced energising current H01H47/04; quick energising of electro-dynamic machines H02P9/08; for quickly de-energising of dynamo-electric generators H02P9/123

Abstract

A clamp assembly comprises a first clamp including a plurality of magnet devices. Each magnet device includes a permanent magnet and a coil surrounding the permanent magnet. The clamp assembly further comprises a controller for pulsing the coils to selectively magnetize and demagnetize the permanent magnets.

Claims

1. A clamp assembly comprising:

a first clamp including a plurality of magnet devices, each magnet device including a permanent magnet and a coil surrounding the permanent magnet; and

a controller for pulsing the coils to selectively magnetize and demagnetize the permanent magnets.

2. The assembly of claim 1, further comprising a second clamp that forms an air gap with the magnets of the first clamp, the second clamp providing a flux path.

3. The assembly of claim 2, wherein the second clamp includes a plate for providing the flux path.

4. The assembly of claim 2, wherein the second clamp includes a plurality of the magnet devices whose permanent magnets are aligned with corresponding permanent magnets in the first clamp.

5. The assembly of claim 1, wherein each permanent magnet includes iron alloy.

6. The assembly of claim 1, wherein the permanent magnets are arranged symmetrically about a process axis.

7. The assembly of claim 1, further comprising at least one keeper for holding the permanent magnets about a process axis, the keeper also providing a flux path between the permanent magnets.

8. The assembly of claim 7, wherein a plurality of keepers extend radially outward from the process axis.

9. The assembly of claim 7, wherein the at least one keeper arranges the permanent magnets in a circular pattern about the process axis.

10. The assembly of claim 1, wherein the permanent magnet of at least one magnet device is bent, and the coil is at one end of the bent permanent magnet.

11. The assembly of claim 1, wherein the controller is configured to supply pulses to selected coils to promote and demote magnetic domain alignment of the permanent magnets.

12. The assembly of claim 11, wherein the controller includes a closed loop control, response to an air gap sensor, for controlling control coil current duration and amplitude for each coil to achieve a target flux density of each permanent magnet.

13. The assembly of claim 1, further comprising a capacitor system for pre-storing energy for pulsing the coils.

14. A system comprising:

a robot end effector including a plurality of magnet devices about a process axis, each magnet device including a permanent magnet and a coil surrounding the permanent magnet; and

a controller for pulsing the coils to selectively magnetize and demagnetize the permanent magnets.

15. The system of claim 14, wherein the end effector includes a tool assembly for performing at least one manufacturing operation along the process axis.

16. The system of claim 14, further comprising a flux-conducting structure for forming an air gap with the magnet devices.

17. The system of claim 16, further comprising at least one robot for positioning the clamp and the flux-conducting structure.

18. A method of clamping a stack, the method comprising:

positioning permanent magnets against a first surface of the stack;

placing a flux-conducting structure against a second surface of the stack; and

applying external magnetic field pulses to the permanent magnets to magnetize and demagnetize the permanent magnets.

19. The method of claim 18, wherein the permanent magnets are positioned about a process axis.

20. The method of claim 18, wherein pulse duration is on the order of milliseconds, and clamping cycle is at least ten seconds.