Power tool and method

Patent metadata

Field	Value
Publication number	US-11697200-B2
Application number	US-201816633200-A
Country	US
Kind code	B2
Filing date	Jun 28, 2018
Priority date	Jul 24, 2017
Publication date	Jul 11, 2023
Grant date	Jul 11, 2023

Abstract

A power tool, including a support structure, a pivot bearing arranged on the support structure, a shaft mounted on the support structure via the pivot bearing, a rotatable tool coupled to the shaft, in particular a saw blade, milling cutter or grinding wheel, a strain gauge arrangement for detecting a mechanical quantity which depends on a force emanating from the tool, and a control device which is adapted to recognize an event and/or a state of the power tool according to the detected mechanical quantity. The strain gauge arrangement is arranged on a stationary structure section coupled in a force-transmitting manner to the pivot bearing and is not arranged on the pivot bearing.

First claim

The invention claimed is:

1. A power tool comprising:
a support structure,
a pivot bearing arranged on the support structure,
a shaft mounted on the support structure via the pivot bearing,
a rotatable tool coupled to the shaft,
a strain gauge arrangement for detecting a mechanical vector quantity which depends on a force emanating from the tool, and
a control device adapted to recognize an event and/or a state of the power tool according to the detected mechanical vector quantity,
wherein the strain gauge arrangement is arranged on a stationary structure section coupled in a force-transmitting manner to the pivot bearing and is not arranged on the pivot bearing, wherein the stationary structure section is part of the support structure and/or is arranged directly on the support structure, wherein the strain gauge arrangement comprises a plurality of strain gauges which are distributed on a path running around the shaft, and wherein the strain gauge arrangement is adapted to detect the mechanical vector quantity as an at least two-dimensional vector by measuring a mechanical quantity underlying the mechanical vector quantity in at least two different spatial directions,
wherein the support structure comprises a bearing flange and the stationary structure section is part of the bearing flange, wherein the pivot bearing comprises an outer ring and an inner ring which is mounted so as to be rotatable relative to the outer ring, wherein the shaft is mounted on the inner ring and the pivot bearing abuts with the outer ring against an radially inward facing surface of the bearing flange, wherein the bearing flange has a pivot bearing receptacle section, in which a pivot bearing receptacle is located, in which the pivot bearing is inserted, and the bearing flange further has a collar section adjoining the pivot bearing receptacle section in an axial direction of the shaft, wherein the strain gauge arrangement is arranged on an radially outward facing outer surface of the collar section.

2. The power tool according to claim 1 , wherein the pivot bearing is arranged directly on the support structure.

3. The power tool according to claim 1 , wherein the support structure reaches around the pivot bearing and/or the stationary structure section reaches around the support structure.

4. The power tool according to claim 1 , wherein the strain gauge arrangement is arranged on a surface of the stationary structure section facing away from the pivot bearing and/or directed radially outwards, and/or is arranged on a radially inwardly directed surface of the stationary structure section.

5. The power tool according to claim 1 , wherein the strain gauge arrangement is arranged, in the axial direction of the shaft, in a same first axial region as the pivot bearing, in a second axial region adjoining the first axial region and/or in a third axial region spaced apart from the first axial region.

6. The power tool according to claim 1 , wherein the control device is adapted to recognize the event and/or the state of the power tool according to a direction and/or a change of direction of the mechanical vector quantity.

7. The power tool according to claim 1 , wherein the control device is adapted to recognize, as the event and/or the state to be recognized, a kickback, a forward sawing, a backward sawing, a plunging of the tool into a workpiece and/or a state of wear of the power tool.

8. The power tool according to claim 7 , wherein the control device is adapted to recognize, as the state to be recognized, a state of wear of the tool.

9. The power tool according to claim 1 , wherein the control device is adapted to provide a signal in response to the recognized event and/or the recognized state, in order to cause the tool to be braked and/or to cause the tool to be moved from an operating position into a safety position.

10. The power tool according to claim 1 , wherein the rotatable tool is a saw blade, a milling cutter or a grinding wheel.

11. The power tool according to claim 1 , wherein the at least two different spatial directions comprise a spatial direction parallel to a feed direction and a spatial direction perpendicular to the feed direction, wherein the feed direction is the direction in which the power tool is to be moved relative to a workpiece in order to machine the workpiece or in which a workpiece is to be moved relative to the power tool in order to machine the workpiece.

12. The power tool according to claim 1 , wherein the path runs around the shaft in circumferential direction of the shaft.

13. The power tool according to claim 1 , wherein the path lies within an axial range of the shaft.

14. A power tool comprising:
a support structure,
a pivot bearing arranged on the support structure,
a shaft mounted on the support structure via the pivot bearing,
a rotatable tool coupled to the shaft,
a strain gauge arrangement for detecting a mechanical vector quantity which depends on a force emanating from the tool, and
a control device adapted to recognize an event and/or a state of the power tool according to the detected mechanical vector quantity,
wherein the strain gauge arrangement is arranged on a stationary structure section coupled in a force-transmitting manner to the pivot bearing and is not arranged on the pivot bearing, wherein the stationary structure section is part of the support structure and/or is arranged directly on the support structure, wherein the strain gauge arrangement comprises a plurality of strain gauges which are distributed on a path running around the shaft, and wherein the strain gauge arrangement is adapted to detect the mechanical vector quantity as an at least two-dimensional vector by measuring a mechanical quantity underlying the mechanical vector quantity in at least two different spatial directions,
wherein the support structure is part of a gearbox housing of the power tool, wherein the pivot bearing comprises an outer ring and an inner ring which is mounted so as to be rotatable relative to the outer ring, wherein the shaft is mounted on the inner ring and the pivot bearing abuts with the outer ring against an radially inward facing surface of the gearbox housing, wherein the strain gauge arrangement is located on a radially outward facing surface of the gearbox housing.

15. A method for retrofitting a power tool with a retrofit arrangement, wherein the power tool comprises a pivot bearing, a shaft mounted via the pivot bearing, the pivot bearing having an outer ring and an inner ring which is mounted so as to be rotatable relative to the outer ring, wherein the shaft is mounted on the inner ring, and the power tool further comprises a rotatable tool coupled to the shaft, and wherein the retrofit arrangement comprises a bearing flange having a pivot bearing receptacle section for receiving the pivot bearing of the power tool, a collar section adjoining the pivot bearing receptacle section, and a strain gauge arrangement arranged on an radially outward facing outer surface of the collar section, the strain gauge arrangement comprising a plurality of strain gauges which are distributed on a path running around the collar section, and wherein the strain gauge arrangement is adapted to detect a mechanical vector quantity as an at least two-dimensional vector by measuring a mechanical quantity underlying the mechanical vector quantity in at least two different spatial directions, the method comprising the step of:
installing the retrofit arrangement in the power tool so that the pivot bearing is inserted into the pivot bearing receptacle section, the pivot bearing abuts with the outer ring a

Assignees

• Festool Gmbh

Inventors

• Rusch Marc
• Schmid Markus

Classifications

• H02K7/145

  Hand-held machine tool · CPC title

• B25B21/00 Primary

  Portable power-driven screw or nut setting or loosening tools; (details or components, e.g. casings, bodies, of portable power-driven tools not particularly related to the operation performed B25F5/00; {for mounting or dismounting wheels B60B29/006}); Attachments for drilling apparatus serving the same purpose (machines B23P19/06) · CPC title

• B25B23/14 Primary

  Arrangement of torque limiters or torque indicators in wrenches or screwdrivers (couplings for transmitting rotation or clutches F16D; devices for measuring torque per se G01L) · CPC title

• B25F5/001 Primary

  Gearings, speed selectors, clutches or the like specially adapted for rotary tools · CPC title

• B27G19/02

  for circular saws · CPC title