Permanent magnetic chucking device with large force differential

Patent metadata

Field	Value
Publication number	US-9570221-B2
Application number	US-201414529088-A
Country	US
Kind code	B2
Filing date	Oct 30, 2014
Priority date	Oct 30, 2014
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

An apparatus usable as a chucking device to temporarily couple two mechanical objects together. In one embodiment, the apparatus includes an arbor configured to receive an at least partially ferromagnetic object; and a magnet assembly. The magnet assembly includes multiple permanent magnets mounted in a soft ferromagnetic enclosure. The magnet assembly is rotatably coupled to the arbor such that the magnet assembly and the arbor are positionable relative to one another in locking and unlocking positions upon relative rotation therebetween. The magnet assembly is configured to exert a pulling force on the object in the locking position and a lesser force in the unlocking position.

First claim

What is claimed is:

1. An apparatus, comprising:
an arbor configured to receive an at least partially ferromagnetic object; and
a magnet assembly, the magnet assembly including multiple permanent magnets mounted in a soft ferromagnetic enclosure,
wherein the magnet assembly is rotatably coupled to the arbor such that the magnet assembly and the arbor are positionable relative to one another in locking and unlocking positions upon relative rotation therebetween,
wherein the magnet assembly is configured to exert a pulling force on the object in the locking position and a lesser force in the unlocking position,
wherein the arbor includes a number of ferromagnetic arms that inhibit a magnetic field generated by the magnet assembly from entering the object when in the unlocking position.

2. The apparatus as recited in claim 1 , wherein the arbor is rotatable and coupled to a motor.

3. The apparatus as recited in claim 1 , wherein the arbor is configured to suspend the object in spaced relation to the permanent magnets when the object is mounted on the arbor and the apparatus is in the locking position.

4. The apparatus as recited in claim 1 , wherein the arbor is configured to cause the object to contact the permanent magnets, or a layer between the object and the permanent magnets, when the object is mounted on the arbor and the apparatus is in the locking position.

5. The apparatus as recited in claim 1 , wherein the magnet assembly is closer to the arbor in the locking position than in the unlocking position.

6. The apparatus as recited in claim 5 , wherein the magnet assembly is actuated between the locking position and the unlocking position by rotation on a ramp or a screw-type thread.

7. The apparatus as recited in claim 5 , comprising a mechanism to selectively prevent rotation of the magnet assembly during the relative rotation, wherein the arbor rotates during the relative rotation.

8. The apparatus as recited in claim 5 , wherein top surfaces of the permanent magnets are flush with a top surface of the soft ferromagnetic enclosure.

9. The apparatus as recited in claim 5 , wherein pairs of the permanent magnets are spaced apart by a distance not less than 0.75 times an average diameter of the permanent magnets in each pair.

10. The apparatus as recited in claim 5 , wherein magnetizations of all of the permanent magnets are oriented in a same direction.

11. The apparatus as recited in claim 5 , wherein magnetizations of all of the permanent magnets are oriented parallel to an axis of the arbor.

12. The apparatus as recited in claim 5 , wherein the arbor is contoured to self-center the object onto the arbor.

13. The apparatus as recited in claim 1 , wherein the object is a tape reel.

14. The apparatus as recited in claim 1 , wherein the arbor is contoured to guide the at least partially ferromagnetic object onto the arbor.

15. The apparatus as recited in claim 1 , wherein angular displacement of the relative rotation between the locking and unlocking positions corresponds to the number of ferromagnetic arms of the arbor.

16. The apparatus as recited in claim 1 , wherein the magnet assembly comprises pairs of the permanent magnets that are magnetized in opposite directions, wherein the ferromagnetic enclosure is recessed with respect to surfaces of the permanent magnets facing the arbor.

17. A system comprising the apparatus as recited in claim 1 and the object, wherein the ferromagnetic arms of the arbor have a shape complementary to a lower surface of the object, such that the lower surface of the object is closer to the magnetic assembly than upper surfaces of the ferromagnetic arms when the object is mounted on the arbor.

18. The system as recited in claim 17 , wherein the object is a tape reel.

19. The apparatus as recited in claim 1 , comprising:
a motor coupled to the arbor;
a magnetic head;
a drive mechanism for passing a magnetic medium over the magnetic head; and
a controller electrically coupled to the motor.

20. An apparatus, comprising:
an arbor configured to receive an at least partially ferromagnetic tape reel; and
a magnet assembly having multiple permanent magnets mounted in a soft ferromagnetic enclosure,
wherein the magnet assembly is rotatably coupled to the arbor such that relative rotation therebetween causes the apparatus to move between locking and unlocking positions,
wherein the magnet assembly is configured to exert a magnetic pulling force on the tape reel in the locking position and a lesser force in the unlocking position,
wherein the arbor includes a number of ferromagnetic arms that inhibit a magnetic field generated by the magnet assembly from entering the object when in the unlocking position.

21. An apparatus, comprising:
an arbor; and
a magnet assembly rotatably coupled to the arbor, the magnet assembly including multiple permanent magnets mounted in a soft ferromagnetic enclosure,
wherein the magnet assembly and the arbor are positionable relative to one another in locking and unlocking positions upon relative rotation therebetween,
wherein a relative movement between the magnet assembly and the arbor towards and away from one another corresponds to movement between the locking and unlocking positions, respectively, wherein the arbor is configured to receive an at least partially ferromagnetic object thereon, wherein the arbor includes ferromagnetic arms that inhibit a magnetic field generated by the magnet assembly from entering the object when in the unlocking position.

22. The apparatus as recited in claim 21 , wherein the arbor is contoured to guide and self-center a ferromagnetic reel onto the arbor.

23. A chucking mechanism having two positions, the first position permitting locking a ferromagnetic reel to a rotatable arbor having precision reference surfaces, and the second position permitting releasing the ferromagnetic reel from the chucking mechanism, the chucking mechanism comprising:
the arbor on which the reel is placed; and
a permanent magnet assembly being movable relative to the arbor, the permanent magnet assembly exerting a pulling force on the reel in the first position and a relatively lesser force in the second position, the permanent magnet assembly including multiple permanent magnets enclosed in a soft ferromagnetic enclosure,
wherein a relative movement between the permanent magnet assembly and the arbor towards and away from one another corresponds to movement between the first and second positions, respectively, wherein the arbor includes ferromagnetic arms that inhibit a magnetic field generated by the magnet assembly from entering the reel when in the second position.

24. The chucking mechanism as recited in claim 23 , wherein at least one of the permanent magnet assembly and the arbor is actuated between the first position and the second position by rotation on a ramp or a screw-type thread.

25. The chucking mechanism as recited in claim 23 , wherein the arbor is contoured to guide and self-center a ferromagnetic reel onto the arbor.

26. The chucking mechanism as recited in claim 23 , wherein the arbor includes ferromagnetic arms that inhibit a magnetic field generated by the permanent magnet assembly from entering a ferromagnetic reel disposed on the arbor when in the second position, wherein the arms do not significantly inhibit the magnetic field generated by the permanent magnet assembly from entering a

Assignees

• IBM

Inventors

• Altknecht David J
• Best James
• Dyer William M
• Jubert Pierre-Olivier
• Labby Ronald R
• Mcclelland Gary M

Classifications

• G11B15/67

  by extracting end of record carrier from container or spool · CPC title

• H01F7/04 Primary

  Means for releasing the attractive force · CPC title

• G11B15/662 Primary

  Positioning or locking of spool or reel · CPC title

• H01F7/0252

  PM holding devices (H01F7/021, H01F7/0215, H01F7/0226 take precedence) · CPC title

• G11B15/672

  Extracting end of record carrier from container or single reel (G11B15/671 takes precedence) · CPC title