Powered tool sharpener with multi-speed abrasive

Patent metadata

Field	Value
Publication number	US-9808902-B2
Application number	US-201715430252-A
Country	US
Kind code	B2
Filing date	Feb 10, 2017
Priority date	Feb 12, 2016
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Method and apparatus for sharpening a cutting tool. In some embodiments, a sharpener has a guide assembly adjacent a moveable abrasive medium. The medium is advanced at a first speed relative to the guide assembly during a coarse sharpening operation in which a user presents the cutting tool against the medium to shape a side of the cutting tool and generate distended material from the cutting edge (e.g., burrs). The medium is subsequently slowed to a lower, second speed for a fine sharpening operation in which the user presents the cutting tool against the medium to remove the distended material and provide a sharpened cutting edge.

First claim

What is claimed is:

1. A sharpener for sharpening a cutting tool having a cutting edge, comprising:
a moveable abrasive medium having an abrasive surface;
a guide assembly adjacent the abrasive medium configured to support a cutting tool thereagainst;
a drive assembly configured to move the abrasive medium with respect to the guide assembly responsive to a control input value; and
a control circuit configured to provide a first control input value to move the medium at a first speed relative to the guide assembly during a coarse sharpening operation in which a user presents the cutting tool against the medium using the guide assembly to shape a side of the cutting tool and generate distended material from the cutting edge, and to subsequently provide a second control input value to transition the medium from the first speed to a lower second speed relative to the guide assembly during a fine sharpening operation in which the user presents the cutting tool against the medium using the guide assembly to remove the distended material and provide a sharpened cutting edge.

2. The sharpener of claim 1 , wherein the drive assembly comprises an electric motor and a transfer assembly to transfer mechanical torque generated by the motor to the medium.

3. The sharpener of claim 1 , wherein the abrasive medium is an endless abrasive belt.

4. The sharpener of claim 1 , wherein the abrasive medium is a rotatable abrasive disc.

5. The sharpener of claim 4 , wherein the rotatable abrasive disc is a flexible abrasive disc, wherein centrifugal forces during rotation of the disc place the disc in a neutral plane.

6. The sharpener of claim 1 , wherein the guide assembly comprises at least one stationary edge guide configured to contactingly engage a portion of the cutting edge of the tool during presentation thereof against the medium.

7. The sharpener of claim 1 , wherein the guide assembly comprises at least one rotatable edge guide configured to rotatingly engage a portion of the cutting edge of the tool during presentation thereof against the medium.

8. The sharpener of claim 1 , wherein the control circuit further directs the transfer assembly to move the medium in a first direction with respect to the guide assembly during the coarse sharpening operation and directs the transfer assembly to move the medium in an opposing, second direction with respect to the guide assembly during the fine sharpening operation.

9. The sharpener of claim 1 , further comprising a sensor adjacent the guide assembly, the sensor configured to sense a presence of the cutting tool within the guide assembly in contact with the abrasive medium.

10. The sharpener of claim 9 , wherein the control circuit further comprises a counter circuit configured to accumulate a count value comprising a total number of successive strokes of the cutting tool through the guide assembly and against the belt by the user while the medium is moved at the first speed, and wherein the control circuit outputs the second control input value to move the medium at the second, lower speed responsive to the accumulated count value reaching a predetermined threshold value.

11. The sharpener of claim 9 , wherein the sensor is configured to detect a change in a characteristic of the cutting edge during the coarse sharpening process, and the control circuit transitions the medium from the first speed to the second speed responsive to the sensor.

12. The sharpener of claim 1 , wherein the control circuit further comprises a timer circuit configured to denote a predetermined elapsed time interval, wherein the control circuit outputs the second control input value to transition the medium from the first, higher speed to the second, lower speed responsive to the timer circuit indicating a conclusion of the predetermined elapsed time interval.

13. The sharpener of claim 1 , wherein the guide assembly is characterized as a first guide assembly adjacent a first side of the abrasive medium, the sharpener further comprising a second guide assembly adjacent an opposing second side of the abrasive medium, the control circuit transitioning from the first speed to the second speed responsive to the user sequentially placing the cutting tool in each of the first and second guide assemblies.

14. The sharpener of claim 1 , further comprising a user indicator device configured to output different visual indications to the user to place and subsequently remove the cutting tool from the guide assembly during continued movement of the abrasive medium.

15. A method for sharpening a cutting tool, comprising:
advancing a moveable abrasive medium having an abrasive surface along a path at a first speed relative to a guide assembly;
presenting the cutting tool against the medium using the guide assembly to apply a coarse sharpening operation to the cutting tool;
reducing a speed of the moveable abrasive medium to a lower, second speed relative to the guide assembly; and
subsequently presenting the cutting tool against the medium using the guide assembly to apply a fine sharpening operation to the cutting tool, wherein a transfer assembly and an electric motor are used to transfer mechanical torque generated by the motor to the medium responsive to a first control input value from the control circuit to establish movement of the medium at the first speed and responsive to a different, second control input value from the control circuit to establish movement of the medium at the second speed.

16. The method of claim 15 , wherein the medium is an endless abrasive belt.

17. The method of claim 16 , wherein the belt is arranged to pass over at least first and second rollers each rotatable about an associated roller axis, the guide assembly having at least one edge guide surface configured to present the cutting edge of the cutting tool along a presentation line that is non-parallel to said roller axes.

18. The method of claim 15 , wherein a burr is formed during the presenting step and the burr is removed during the subsequently presenting step.

19. The method of claim 15 , wherein the abrasive medium is a rotatable abrasive disc.

20. The method of claim 19 , wherein the rotatable abrasive disc is a flexible abrasive disc, and wherein centrifugal forces during rotation of the disc place the disc in a neutral plane.

21. The method of claim 15 , wherein the control circuit directs the transfer assembly to move the medium in a first direction with respect to the guide assembly during the coarse sharpening operation and directs the transfer assembly to move the medium in an opposing, second direction with respect to the guide assembly during the fine sharpening operation.

22. The method of claim 15 , further comprising using a sensor adjacent the guide assembly to output an electrical signal responsive to detection, by the sensor, of a presence of the cutting tool within the guide assembly in contact with the abrasive medium.

23. The method of claim 15 , further comprising using a counter circuit configured to accumulate a count value comprising a total number of successive strokes of the cutting tool through the guide assembly and against the medium by the user while the medium is moved at the first speed, and transitioning the medium from the first speed to the second speed responsive to the accumulated count value from the counter circuit reaching a predetermined threshold value.

24. The method of claim 15 , further comprising using a sensor to de

Assignees

• Darex Llc

Inventors

• Dovel Daniel T

Classifications

• B24B21/002

  for grinding edges or bevels · CPC title

• B24B3/54 Primary

  of hand or table knives · CPC title

• B24B51/00

  Arrangements for automatic control of a series of individual steps in grinding a workpiece (if applicable to other machine tools, G05B takes precedence) · CPC title

• B24B41/066

  adapted for supporting work in the form of tools, e.g. drills · CPC title

• B24B49/10

  involving electrical means (B24B49/02, B24B49/08 take precedence) · CPC title