MAGNETIC CHUCK AND METHOD FOR PRODUCING A MAGNETIC CHUCK

• US 20150279536A1
• Filed: 03/26/2015
• Published: 10/01/2015
• Est. Priority Date: 03/31/2014
• Status: Active Grant

• Current Assignee: SOPH Inc.
• Original Assignee: Soph International Limited
• Inventors: Ding, Hong
• Granted Patent: US 9,601,250 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23Q 3/1546 using permanent magnets
• CPC Class Codes: H01F 7/0252 PM holding devices H01F7/021, H01F7/0215, H01F7/0226 take precedence
• CPC Class Codes: Y10T 29/49075 including permanent magnet or core

Abstract

The invention is directed to a magnetic chuck and a method for producing a magnetic chuck. The magnetic chuck comprises an upper base made of a single piece of magnetic-conductive material and having a top surface, sidewalls extending orthogonally from the top surface, a cavity formed within the upper base with an open end opposite to the top surface and an opposite closed end directed toward the top surface. A plurality of cores extends orthogonally from the top surface and into the cavity, wherein a plurality of permanent magnets is arranged in the cavity. A reversible magnet is arranged between each of the cores and a lower base; and an excitation coil is arranged around the circumference of each reversible magnet. A portion of the cavity between the permanent magnets and the closed end of the cavity is filled with non-magnetic-conductive material.

Claims

1-15. -15. (canceled)

16. A magnetic chuck, comprising:

an upper base made of a single piece of magnetic-conductive material and having a top surface, sidewalls extending orthogonally from the top surface, a cavity formed within the upper base with an open end opposite to the top surface and an opposite closed end directed toward the top surface, and a plurality of cores extending orthogonally from the top surface and into the cavity;

a lower base;

a plurality of permanent magnets arranged within the cavity;

a reversible magnet arranged between each of the cores and the lower base; and

an excitation coil arranged around the circumference of each reversible magnet;

wherein a portion of the cavity between the permanent magnets and the closed end of the cavity is filled with a non-magnetic-conductive material.

17. The magnetic chuck according to claim 16, wherein an extension of the upper base between the top surface and the closed end of the cavity in a direction orthogonal to the top surface is between 0.1 mm and 5 mm.

18. The magnetic chuck according claim 17, wherein the extension of the upper base between the top surface and the closed end of the cavity in a direction orthogonal to the top surface is between 3 mm and 4 mm.

19. The magnetic chuck according to claim 17, wherein the extension of the upper base between the top surface and the closed end of the cavity in a direction orthogonal to the top surface is between 1 mm and 2 mm.

20. The magnetic chuck according to claim 16, wherein the portion of the cavity between the permanent magnets and the closed end of the cavity has an extension in a direction orthogonal to the top surface of about 5-10 mm.

21. The magnetic chuck according to claim 20, wherein the portion of the cavity between the permanent magnets and the closed end of the cavity has an extension in a direction orthogonal to the top surface of about 6 mm.

22. The magnetic chuck according to claim 16, wherein the portion of the cavity between the permanent magnets and the closed end of the cavity has an extension in a direction parallel to the top surface that is smaller than the extension of the permanent magnets in the same direction.

23. The magnetic chuck according to claim 22, wherein the extension of the closed end of the cavity in the direction parallel to the top surface is less than 50% smaller than the extension of the permanent magnets in the same direction.

24. The magnetic chuck according to claim 16, wherein a spacer comprising a non-magnetic-conductive material is arranged within the portion of the cavity between each permanent magnet and the closed end of the cavity.

25. The magnetic chuck according to claim 24, wherein the spacer is made of pre-cured epoxy resin.

26. The magnetic chuck according to claim 24, wherein the spacer has an extension in a direction orthogonal to the top surface of 5-10 mm.

27. The magnetic chuck according to claim 26, wherein the spacer has an extension in a direction orthogonal to the top surface of about 6 mm.

28. A method for producing a magnetic chuck, the method comprising the steps of:

providing a single piece of magnetic-conductive material having an upper base with a top surface;

forming a cavity with an open end opposite to the top surface and an opposite closed end directed toward the top surface into the upper base such that from a top surface, sidewalls extend orthogonally from the top surface, and a plurality of cores extend orthogonally from the top surface and into the cavity;

arranging a plurality of permanents magnet in the cavity to form a portion in the cavity between the permanent magnets and the closed end of the cavity;

arranging a reversible magnet between each of the cores and a lower base;

arranging an excitation coil around the circumference of each reversible magnet;

filling the portion of the cavity between the permanent magnets and the closed end of the cavity with a non-magnetic-conductive material; and

filling a remaining volume of the cavity with non-magnetic-conductive material.

29. The method according to claim 28, wherein the portion of the cavity between the permanent magnets and the closed end of the cavity is filled with non-magnetic conductive material before the permanent magnets are placed into the cavity.

30. The method according to claim 28, wherein the cavity is formed such that the portion of the cavity between the permanent magnets and the closed end of the cavity has an extension in a direction parallel to the top surface that is smaller than the extension of the permanent magnets in the same direction.

31. The method according to claim 28, wherein a spacer comprising a non-magnetic-conductive material is arranged within the portion of the cavity between the permanent magnets and the closed end of the cavity before the permanent magnets are placed into the cavity.