Magnetic base

Patent metadata

Field	Value
Publication number	US-11279019-B2
Application number	US-202016876808-A
Country	US
Kind code	B2
Filing date	May 18, 2020
Priority date	May 16, 2019
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

A magnetic base for an electric machine tool, in particular for a magnetic core drilling machine, having a body in which is accommodated at least one first permanent magnet, the magnetic force of which combines with the magnetic force of at least one second permanent magnet to form a resultant holding force, wherein the at least one second permanent magnet is supported in the body such that it can rotate about a rotation axis through an angle of rotation between a first position in which the resultant holding force of the magnetic base is maximized and a second position in which the resultant holding force of the magnetic base is minimized, and having a controller for rotating the second permanent magnet between the first position and the second position.

First claim

What is claimed is:

1. A magnetic base for an electric machine tool, the magnetic base comprising:
a body in which is accommodated at least one first permanent magnet, a magnetic force of which combines with a magnetic force of at least one second permanent magnet to form a resultant holding force, wherein the at least one second permanent magnet is supported in the body such that the at least one second permanent magnet rotates about a rotation axis through an angle of rotation between a first position in which the resultant holding force of the magnetic base is maximized and a second position in which the resultant holding force of the magnetic base is minimized;
a controller for rotating the at least one second permanent magnet between the first position and the second position, the controller being supported such that it pivots so as to pivot about a pivot axis through a pivot angle between a first end position in which the at least one second permanent magnet is located in the first position and a second end position in which the at least one second permanent magnet is located in the second position; and
a transmission configured such that a ratio between the pivot angle of the controller and the angle of rotation of the at least one second permanent magnet is between 1:3.6 and 1:1.5, the transmission being arranged between the controller and the at least one second permanent magnet,
wherein a spring element preloading the at least one second permanent magnet into the first position is arranged between the transmission and the body, and
wherein the pivot angle between the first end position and the second end position is between 50° and 120°.

2. The magnetic base according to claim 1 , wherein the pivot angle between the first end position and the second end position is 70°.

3. The magnetic base according to claim 1 , wherein the transmission has gear teeth whose gear ratio is constant.

4. The magnetic base according to claim 3 , wherein the gear teeth are composed of a first gear carrier and of a second gear carrier.

5. The magnetic base according to claim 4 , wherein the first gear carrier, which is connected in a rotationally fixed manner to the controller, is designed as a segment of a circle whose angle corresponds essentially to the pivot angle between the first end position and the second end position.

6. The magnetic base according to claim 4 , wherein the second gear carrier is circular.

7. The magnetic base according to claim 4 , wherein a number of teeth of the second gear carrier is between 4 and 8.

8. The magnetic base according to claim 4 , wherein at least one stop is associated with the body for limiting the pivoting of the controller.

9. The magnetic base according to claim 8 , wherein the at least one stop directly limits a motion of the transmission.

10. The magnetic base according to claim 8 , wherein the at least one stop is arranged in an interior of the body and limits a motion of the first gear carrier.

11. The magnetic base according to claim 1 , wherein the spring element is a torsion spring.

12. The magnetic base according to claim 1 , wherein a location of the controller in the first end position and/or in the second end position is defined by a detent connection between the body and the controller.

13. The magnetic base according to claim 12 , wherein the detent connection includes a first detent seat that defines the first end position of the controller, the first detent seat being arranged in the body.

14. The magnetic base according to claim 13 , wherein a second detent seat that defines an intermediate position in which the resultant holding force is between the minimum holding force and the maximum holding force is implemented between the first end position and the second end position.

15. The magnetic base according to claim 12 , wherein a detent projection that has at least one guide bevel is arranged on the controller.

16. The magnetic base according to claim 1 , wherein the controller is designed as a control lever.

17. The magnetic base according to claim 16 , wherein the control lever is adapted to be tilted against a force of a return element about a tilt axis that is oriented substantially perpendicularly to the pivot axis.

18. The magnetic base according to claim 1 , wherein a force indicator, to read out the resultant holding force, is arranged on an end face of the body facing away from the controller.

19. The magnetic base according to claim 18 , wherein the force indicator is connected in a rotationally fixed manner to the at least one second permanent magnet.

20. The magnetic base according to claim 1 , wherein the at least one second permanent magnet is embedded in an essentially cylindrical casing that is rotatably mounted in the body.

21. The magnetic base according to claim 1 , wherein a plurality of the at least one first permanent magnet is provided, and wherein the plurality of the at least one first permanent magnet are combined into a first subgroup and into a second subgroup, which are each accommodated in the body so as to be spatially separated from one another.

22. An electric machine tool comprising a magnetic base according to claim 1 .

23. A magnetic base for an electric machine tool, the magnetic base comprising:
a body in which is accommodated at least one first permanent magnet, a magnetic force of which combines with a magnetic force of at least one second permanent magnet to form a resultant holding force, wherein the at least one second permanent magnet is supported in the body such that the at least one second permanent magnet rotates about a rotation axis through an angle of rotation between a first position in which the resultant holding force of the magnetic base is maximized and a second position in which the resultant holding force of the magnetic base is minimized;
a controller for rotating the at least one second permanent magnet between the first position and the second position, the controller being supported so as to pivot about a pivot axis through a pivot angle between a first end position in which the at least one second permanent magnet is located in the first position and a second end position in which the at least one second permanent magnet is located in the second position; and
a transmission configured such that a ratio between the pivot angle of the controller and the angle of rotation of the at least one second permanent magnet is between 1:3.6 and 1:1.5, the transmission being arranged between the controller and the at least one second permanent magnet,
wherein a switching element for switching a switch that is connected to the magnetic base is associated with the at least one second permanent magnet.

24. The magnetic base according to claim 23 , wherein the switching element is a switching ball embedded in a casing, wherein the at least one second permanent magnet is also embedded in the casing.

25. A magnetic base for an electric machine tool, the magnetic base comprising:
a body in which is accommodated at least one first permanent magnet, a magnetic force of which combines with a magnetic force of at least one second permanent magnet to form a resultant holding force, wherein the at least one second permanent magnet is supported in the body such that the at least one second permanent magnet rotates about a rotation axis through an angle of rotation between a first position in which the resultant holding force of the magne

Assignees

• Fein C & E Gmbh

Inventors

• Scherrenbacher Stefan
• Denzel Sergej
• Huaylinos Dolderer Gabriel

Classifications

• H01F7/04

  Means for releasing the attractive force · CPC title

• B25H1/0071 Primary

  by magnetic means · CPC title

• H01F7/0252

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

• B25H1/00 Primary

  Work benches; Portable stands or supports for positioning portable tools or work to be operated on thereby · CPC title

• Y10T408/554

  Magnetic or suction means · CPC title