Hand-held and hand-guided power tool having a working element releasably attached thereto, and working element in the form of a backing pad for such a power tool

Abstract

The invention refers to a plate-like backing pad member (9) for use with a hand-held and hand-guided power tool (1). The backing pad member (9) is adapted for releasable attachment to a driving shaft (27) of the power tool (1) by means of a mechanical form fit connection arrangement comprising a protrusion member (16) connected to the driving shaft (27) and a recess member (17) connected to the backing pad member (9). The form fit connection is releasable in an axial direction running parallel to a rotational axis (13) of the backing pad member (9). The protrusion member (16) is held in the axial direction within the recess member (17) by means of an axial holding arrangement. It is suggested that the axial holding arrangement comprises at least one permanent magnet (40) on the one hand and at least one ferromagnetic element (41) or at least one further permanent magnet on the other hand exerting a magnetic force for holding the protrusion member (16) in the axial direction within the recess member (17). The at least one permanent magnet (40) or the at least one ferromagnetic element (41) or the at least one further permanent magnet is located in or makes part of the recess member (17).

1 . Plate-like backing pad member ( 9 ) for use with a hand-held and hand-guided power tool ( 1 ) comprising a housing ( 2 ) with a driving motor ( 11 ) located therein for actuating a driving shaft ( 27 ) upon operation of the driving motor ( 11 ), the plate-like backing pad member ( 9 ) having a rotational axis ( 13 ), wherein the plate-like backing pad member ( 9 ) is adapted for releasable attachment to the driving shaft ( 27 ) by means of a mechanical form fit connection arrangement comprising at least one protrusion member ( 16 ) directly or indirectly connected to the driving shaft ( 27 ) and at least one recess member ( 17 ) connected to the plate-like backing pad member ( 9 ), the mechanical form fit connection arrangement being adapted for providing a torque proof connection between the at least one protrusion member ( 16 ) and the at least one recess member ( 17 ) in a plane extending perpendicular to the rotational axis ( 13 ) of the plate-like backing pad member ( 9 ), wherein the mechanical form fit connection arrangement is releasable in an axial direction running parallel to the rotational axis ( 13 ) of the plate-like backing pad member ( 9 ), wherein the at least one protrusion member ( 16 ) is held in the axial direction within the at least one recess member ( 17 ) by means of an axial holding arrangement, characterized in that the axial holding arrangement comprises at least one permanent magnet ( 40 ) and either least one ferromagnetic element ( 41 ) or at least one further permanent magnet exerting a magnetic force for holding the at least one protrusion member ( 16 ) in the axial direction within the at least one recess member ( 17 ), wherein the at least one permanent magnet ( 40 ), or the at least one ferromagnetic element ( 41 ), or the at least one further permanent magnet is located in or makes part of the at least one recess member ( 17 ). 
     
     
         2 . The plate-like backing pad member ( 9 ) according to  claim 1 , wherein the plate-like backing pad member ( 9 ) has two opposing surfaces extending in parallel to each other, the surfaces comprising a first bottom surface ( 9   a ) for releasable attachment of a sheet-like polishing or abrasive member ( 14 ) by means of a hook-and-loop fastener. 
     
     
         3 . The plate-like backing pad member ( 9 ) according to  claim 2 , wherein the opposing surfaces of the plate-like backing pad member ( 9 ) comprise an opposite top surface ( 9   b ) with a backing pad-connection arrangement ( 15 ) attached thereto, the backing pad-connection arrangement ( 15 ) comprising the at least one recess member ( 17 ). 
     
     
         4 . The plate-like backing pad member ( 9 ) according to  claim 1 , wherein the plate-like backing pad member ( 9 ) is made of a semi-rigid plastic material and comprises a metal insert moulded into the plastic material during production of the plate-like backing pad member ( 9 ) by means of a moulding or an injection moulding process, the metal insert forming at least part of the at least one recess member ( 17 ) and constituting the at least one ferromagnetic element ( 41 ) or the at least one further permanent magnet. 
     
     
         5 . The plate-like backing pad member ( 9 ) according to  claim 1 , wherein the at least one recess member ( 17 ) in the plane extending perpendicular to the rotational axis ( 13 ) of the plate-like backing pad member ( 9 ) has a circumferential form comprising two opposing arc-shaped sections ( 18   a ) of a circle with the rotational axis ( 13 ) running through the centre of the circle, and the plate-like backing pad member ( 9 ) further comprising two opposing straight walls ( 18   b ) running substantially parallel to one another and interconnecting the two opposing arc-shaped sections ( 18   a ). 
     
     
         6 . The plate-like backing pad member ( 9 ) according to  claim 1 , wherein the at least one recess member ( 17 ) in the plane extending perpendicular to the rotational axis ( 13 ) of the backing pad member ( 9 ) has a circumferential form comprising a circle with the rotational axis ( 13 ) running through the centre of the circle, and the plate-like backing pad member ( 9 ) further comprising two grooves extending on opposite sides of the circle radially outwards. 
     
     
         7 . The plate-like backing pad member ( 9 ) according to  claim 1 , wherein the at least one recess member ( 17 ) in the plane extending perpendicular to the rotational axis ( 13 ) of the plate-like backing pad member ( 9 ) has a circumferential form of a polygon, including a polygon having equal side lengths, with the rotational axis ( 13 ) running through the centre of gravity of the polygon. 
     
     
         8 . The plate-like backing pad member ( 9 ) according to  claim 1 , wherein a plurality of permanent magnets ( 40 ), including four permanent magnets, are located in the recess member ( 17 ) around and equidistant to the rotational axis ( 13 ) of the plate-like backing pad member ( 9 ), with neighbouring permanent magnets ( 40 ) having opposite polarities. 
     
     
         9 . The plate-like backing pad member ( 9 ) according to  claim 8 , wherein the plurality of permanent magnets ( 40 ) are located so that neighbouring permanent magnets ( 40 ) are in direct lateral abutment with one another. 
     
     
         10 . The plate-like backing pad member ( 9 ) according to  claim 8 , wherein the plurality of permanent magnets ( 40 ) are located in direct contact with one another along the rotational axis ( 13 ) of the plate-like backing pad member ( 9 ). 
     
     
         11 . The plate-like backing pad member ( 9 ) according to one of the  claims 8  to  10 , wherein each of the plurality of permanent magnets ( 40 ) is formed as a respective triangle having a respective vertex angle, including an isosceles triangle, and wherein all triangles are dimensioned so that the sum of all vertex angles is 360°. 
     
     
         12 . The plate-like backing pad member ( 9 ) according to  claim 8 , wherein each of the plurality of permanent magnets ( 40 ) is termed with a circular sector, and wherein all circular sectors are dimensioned so that all permanent magnets ( 40 ) together form a circle. 
     
     
         13 . Hand-held and hand-guided power tool ( 1 ) comprising a housing ( 2 ) with a driving motor ( 11 ) located therein for actuating a driving shaft ( 27 ) upon operation of the driving motor ( 11 ) and further comprising a backing pad member ( 9 ) performing a working movement about its rotational axis ( 13 ) in a working plane extending perpendicular to its rotational axis ( 13 ) upon actuation of the driving shaft ( 27 ), wherein the backing pad member ( 9 ) is attached to the driving shaft ( 27 ) by means of a mechanical form fit connection arrangement comprising at least one protrusion member ( 16 ) directly or indirectly connected to the driving shaft ( 27 ) and at least one recess member ( 17 ) connected to the backing pad member ( 9 ), the mechanical form fit connection arrangement being adapted for providing a torque proof connection between the at least one protrusion member ( 16 ) and the at least one recess member ( 17 ) in a plane extending perpendicular to the rotational axis ( 13 ) of the backing pad member ( 9 ), wherein the mechanical form fit connection arrangement is releasable in an axial direction running parallel to the rotational axis ( 13 ) of the backing pad member ( 9 ), wherein the at least one protrusion member ( 16 ) is held in the axial direction within the al least one recess member ( 17 ) by means of an axial holding arrangement, characterized in that the axial holding arrangement comprises at least one permanent magnet ( 40 ) and either at least one ferromagnetic element ( 41 ) or at least one further permanent magnet exerting a magnetic force for holding the at least one protrusion member ( 16 ) in the axial direction within the at least one recess member ( 17 ), wherein at least part of the axial magnetic holding arrangement ( 40 ,  41 ) forms an integral part of at least part of the mechanical form fit connection arrangement ( 16 ,  17 ). 
     
     
         14 . The hand-held and hand-guided power tool ( 1 ) according to  claim 13 , wherein the at least one permanent magnet ( 40 ), or the at least one ferromagnetic element ( 41 ), or the at least one further permanent magnet is located in or makes part of the at least one recess member ( 17 ). 
     
     
         15 . The hand-held and hand-guided power tool ( 1 ) according to  claim 13 , wherein the at least one ferromagnetic element ( 41 ), or the at least one further permanent magnet, or the at least one permanent magnet ( 40 ) is attached to or makes part of the at least one protrusion member ( 16 ). 
     
     
         16 . The hand-held and hand-guided power tool ( 1 ) according to  claim 13 , wherein the protrusion member ( 16 ) in the plane extending perpendicular to the rotational axis ( 13 ) of the backing pad member ( 9 ) has a circumferential form corresponding to the circumferential form of the at least one recess member ( 17 ). 
     
     
         17 . The plate-like backing pad member ( 9 ) according to  claim 2 , wherein the plate-like backing pad member ( 9 ) is made of a semi-rigid plastic material and comprises a metal insert moulded into the plastic material during production of the plate-like backing pad member ( 9 ) by means of a moulding or an injection moulding process, the metal insert forming at least part of the at least one recess member ( 17 ) and constituting the at least one ferromagnetic element ( 41 ) or the at least one further permanent magnet. 
     
     
         18 . The plate-like backing pad member ( 9 ) according to  claim 2 , wherein the at least one recess member ( 17 ) in the plane extending perpendicular to the rotational axis ( 13 ) of the plate-like backing pad member ( 9 ) has a circumferential form comprising two opposing arc-shaped sections ( 18   a ) of a circle with the rotational axis ( 13 ) running through the centre of the circle, and the plate-like backing pad member ( 9 ) further comprising two opposing straight walls ( 18   b ) running substantially parallel to one another and interconnecting the two opposing arc-shaped sections ( 18   a ). 
     
     
         19 . The plate-like backing pad member ( 9 ) according to  claim 2 , wherein the at least one recess member ( 17 ) in the plane extending perpendicular to the rotational axis ( 13 ) of the backing pad member ( 9 ) has a circumferential form comprising a circle with the rotational axis ( 13 ) running through the centre of the circle, and the plate-like backing pad member ( 9 ) further comprising two grooves extending on opposite sides of the circle radially outwards. 
     
     
         20 . The plate-like backing pad member ( 9 ) according to  claim 2 , wherein the at least one recess member ( 17 ) in the plane extending perpendicular to the rotational axis ( 13 ) of the plate-like backing pad member ( 9 ) has a circumferential form of a polygon, including a polygon having equal side lengths, with the rotational axis ( 13 ) running through the centre of gravity of the polygon.