Abrading – Abrading process – Razor – knife – or scissors sharpening
Reexamination Certificate
1999-02-05
2001-03-27
Banks, Derris H. (Department: 3723)
Abrading
Abrading process
Razor, knife, or scissors sharpening
C451S349000
Reexamination Certificate
active
06206761
ABSTRACT:
TECHNICAL FIELD
This invention relates to a device for grinding the bedknife of a lawnmower, in particular lawn or grass mowers of the type having a cylindrical cutting unit comprising blades in part helical form. The invention also provides a method for grinding the bedknife of a lawnmower.
Cylindrical or reel mowers comprise one or more cylinders or reels bearing a plurality of part helical blades mounted for rotation about a horizontal axis transverse to the direction of motion of the mower. Each cylinder or reel cuts the grass in cooperation with an elongate bottom blade, commonly referred to as a bedknife, which is disposed in alignment with the reel and positioned for the grass to be positioned accurately allowing the helical blade to cut the grass in a transverse scything motion. The front face of the bedknife becomes worn during grass cutting and is required to be sharpened periodically by grinding.
The term lawnmower is used to encompass all mowers employing this blade configuration, whether they are tractor mounted, towed, or are walking mowers.
BACKGROUND ART
It is known to use magnets to secure the bedknife to the grinding device. However, the magnets may distort the bedknife during the grinding process leading to an imperfect cutting edge.
GENERAL DISCUSSION OF INVENTION
The present invention seeks to overcome or at least mitigate the problems of the prior art.
One aspect of the invention provides a device for grinding the bedknife of a lawnmower, which device comprises support means to support the bedknife during grinding, at least one electromagnet energized to hold the bedknife in a pre-selected position relative to the support means, grinding means to grind the bedknife and control means to automatically de-energize the or each electromaget upon commencement of grinding. Preferably, the or each electromagnet is energized by means of a manual switch.
According to another optional feature of this aspect of the invention, securing means is provided by end mounted brackets which secure the bedknife relative the support means. Preferably, one bracket is positioned adjacent each axial end of the bedknife. Even more preferably, at least one bracket is slidably fixed to secure the bedknife to the mounting bar.
According to another optional feature of this aspect of the invention a mounting bar may provide support along the entire length of the bedknife.
According to another optional feature of this aspect of the invention the electromagnets may be mounted flush with the top face of the mounting bar.
A second aspect of the invention provides a method for grinding the bedknife of a lawnmower, comprising placing the bedknife of the lawnmower on a mounting bar, manually energising at least one electromagnet, securing the bedknife to at least one mounting bracket, commencing the grinding of the bedknife at which time the or each electromagnet is automatically de-energized, ceasing grinding the bedknife at which time the or each electromaget is automatically energized, freeing the bedknife from the or each mounting bracket, manually de-energizing the or each electromagnet to permit the removal of the bedknife.
REFERENCES:
patent: 5685768 (1997-11-01), Bernhard et al.
patent: 5725415 (1998-03-01), Bernhard
patent: 5893792 (1999-04-01), Scott
Banks Derris H.
Marquis Harold L.
Schneider Ryan A.
Troutman Sanders LLP
LandOfFree
Bedknife grinding device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bedknife grinding device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bedknife grinding device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2442258