Hand-held and hand-guided power tool having a working element releasably attached thereto, and for such a power tool

• US 10,661,407 B2
• Filed: 03/21/2019
• Issued: 05/26/2020
• Est. Priority Date: 03/21/2018
• Status: Active Grant

• Current Assignee: Guido Valentini
• Original Assignee: Guido Valentini
• Inventors: Valentini, Guido
• Primary Examiner(s): Rose, Robert A
• Application Number:
  US16/360,569
• Publication Number:
  US 20190291233A1
• Time in Patent Office: 432 Days
• Field of Search: 451357, 451359, 451344
• CPC Class Codes: B24B 23/03 the tool being driven in a combined movement
• CPC Class Codes: B24B 23/04 with oscillating grinding tools; Accessories therefor
• CPC Class Codes: B24B 45/006 Quick mount and release means for disc-like wheels, e.g. on power tools

Abstract

A hand-held machine tool (1) for sanding or polishing a workpiece features a housing (2); a motor (4) for rotating a tool shaft (5) of the machine tool about its axis of rotation (6); and a backing pad (3) for releasable attachment of a sanding or polishing element thereto and eccentrically attachable to the tool shaft by an eccentric element (11) to allow the backing pad to perform a working movement. The machine tool implements different working movements of the backing pad attached thereto. The housing includes first magnetic elements (16) facing the backing pad. The backing pad attached to the eccentric element includes second magnetic elements (17) facing the housing. The machine tool implements a first working movement if a magnetic force is active between some first and second magnetic elements and a second working movement if no magnetic force is active between the first and second magnetic elements.

Claims

1. Hand-held machine tool (1) for sanding or polishing a workpiece, the hand-held machine tool (1) comprising:

a housing (2),

a motor (4) for actuating a tool shaft (5) of the hand-held machine tool (1) and for making the tool shaft (5) rotate about its axis of rotation (6), and

a backing pad (3) for releasable attachment of a sanding element or a polishing element thereto and eccentrically attachable to the tool shaft (5) by means of an eccentric element (11) in such a way as to allow the backing pad (3) to perform a working movement,

wherein the hand-held machine tool (1) is adapted for realizing two different types of working movements of the backing pad (3) attached thereto,

wherein the housing (2) of the hand-held machine tool (1) comprises a plurality of first magnetic elements (16) facing the backing pad (3), and that the backing pad (3) attached to the eccentric element (11) comprises a plurality of second magnetic elements (17) facing the housing (2), and

wherein the hand-held machine tool (1) is adapted for realizing a first type of working movement if a magnetic force is active between at least some of the plurality of the first and second magnetic elements (16, 17) and a second type of working movement if no magnetic force is active between the plurality of the first and second magnetic elements (16, 17).

2. Hand-held machine tool (1) according to claim 1, wherein the hand-held machine tool (1) is adapted for realizing the first type of working movement if the backing pad (3) with the plurality of second magnetic elements (17) facing the housing (2) is attached to the eccentric element (11) and the second type of working movement if another backing pad (3) without the plurality of the second magnetic elements (17) is attached to the eccentric element (11).

3. Hand-held machine tool (1) according to claim 2, wherein the plurality of the first magnetic elements (16) is embodied as permanent magnets.

4. Hand-held machine tool (1) according to claim 1, wherein the plurality of the first magnetic elements (16) is embodied as solenoids, and wherein the hand-held machine tool (1) is adapted for realizing the first type of working movement if the solenoids (16) are activated and generate a magnetic force acting on at least some of the plurality of the second magnetic elements (17) of the backing pad (3) attached to the eccentric element (11) and a second type of working movement if the solenoids (16) are deactivated and generate no magnetic force.

5. Hand-held machine tool (1) according to claim 1, wherein the plurality of the second magnetic elements (17) is embodied as permanent magnets or pieces of ferromagnetic material.

6. Hand-held machine tool (1) according to claim 1, wherein the backing pad (3) attached to the eccentric element (11) is able to freely rotate about its longitudinal centre axis (9) in respect to the eccentric element (11), and wherein the longitudinal axis (9) of the backing pad (3) is spaced apart from and runs essentially parallel to the axis of rotation (6) of the tool shaft (5).

7. Hand-held machine tool (1) according to claim 6, wherein the backing pad (3) is attached to a rotary element (8) in a torque proof manner in respect to the longitudinal axis (9), and wherein the rotary element (8) is attached to the eccentric element (11) freely rotatable about the longitudinal axis (9).

8. Hand-held machine tool (1) according to claim 7, wherein the torque proof attachment of the backing pad (3) to the rotary element (8) is realized by positive locking in a plane extending essentially perpendicular in respect to the longitudinal axis (9), and wherein the backing pad (3) is releasably fixed to the rotary element (8) in the direction of the longitudinal axis (9) by means of a screw (8a) or by means of magnetic force.

9. Hand-held machine tool (1) according to claim 6, wherein the second working movement is a random orbital movement.

10. Hand-held machine tool (1) according to claim 1, wherein the first working movement is a purely orbital movement, and wherein the backing pad (3) is held in a discrete rotational position in respect to the longitudinal axis (9) by means of magnetic force resulting from interaction between at least some of the plurality of the first and second magnetic elements (16, 17).

11. Hand-held machine tool (1) according to claim 1, wherein the plurality of the first magnetic elements (16) of the housing (2) are located around the axis of rotation (6) of the tool shaft (5), the plurality of the first magnetic elements (16) having the same given distance to the axis of rotation (6) and being circumferentially evenly spaced apart from one another.

12. Hand-held machine tool (1) according to claim 1, wherein the second magnetic elements (17) of the backing pad (3) are located around a longitudinal centre axis (9) of the backing pad (3), the plurality of the second magnetic elements (17) having the same given distance to the longitudinal axis (9) and being circumferentially evenly spaced apart from one another.

13. Hand-held machine tool (1) according to claim 1, wherein the positions of the plurality of the first magnetic elements (16) and of the plurality of the second magnetic elements (17) are such that in respective discrete rotational positions of the backing pad (3) at least some of the plurality of the second magnetic elements (17) face corresponding first magnetic elements (16).

14. Hand-held machine tool (1) according to claim 13, wherein sizes of surfaces of the plurality of the first and second magnetic elements (16, 17) are designed such that during a purely orbital movement of the backing pad (3) the surfaces of the plurality of the second magnetic elements (17) are each in continuous coverage with corresponding surfaces of the plurality of the first magnetic elements (16).

15. Hand-held machine tool (1) according to claim 14, wherein the surfaces of the plurality of the first and second magnetic elements (16, 17) have a circular form, and a diameter (2×

R₁₆;

2×

R₁₇) of the surfaces of the plurality of the first or second magnetic elements (16;

17) is at least the size of a diameter (2×

R₁₇;

2×

R₁₆) of corresponding surfaces of other second or first magnetic elements (17;

16) plus the size of the orbit (2×

R₂₅), which the backing pad (3) performs during its purely orbital movement.

16. Hand-held machine tool (1) according to claim 2, wherein the plurality of the second magnetic elements (17) is embodied as permanent magnets or pieces of ferromagnetic material.

17. Hand-held machine tool (1) according to claim 2, wherein the backing pad (3) attached to the eccentric element (11) is able to freely rotate about its longitudinal centre axis (9) in respect to the eccentric element (11), and wherein the longitudinal axis (9) of the backing pad (3) is spaced apart from and runs essentially parallel to the axis of rotation (6) of the tool shaft (5).

18. Hand-held machine tool (1) according to claim 7, wherein the second working movement is a random orbital movement.

19. Hand-held machine tool (1) according to claim 8, wherein the second working movement is a random orbital movement.

20. Hand-held machine tool (1) according to claim 2, wherein the first working movement is a purely orbital movement, and wherein the backing pad (3) is held in a discrete rotational position in respect to the longitudinal axis (9) by means of magnetic force resulting from interaction between at least some of the plurality of the first and second magnetic elements (16, 17).