Patent Application
20170209980
Conventional grinder guards are commonly fixed in position or operate on a spring return from a full guard position of a grinder blade to a retractable operating position of the grinder guard. The grinder guard may be pushed aside by an operator's hand or by a workpiece which keeps the guard retracted. However, the spring tension on a retracted grinder guard is felt by the operator as a force against the workpiece which interferes with the operator's craftsmanship. Worse, the spring force against the grinder guard during its retraction can create a temptation by the operator to bypass the guard and hold it fully retracted by his hand or to remove it from the grinder completely to obviate the retracting spring force and an interfering grinder guard all together. Fixed and non-adjustable grinder guards require the operator to get into ackward or even dangerous body positions to accomplish certain work.
Some grinder guards therefore present an interference in the operation of the grinder at best and present a grave safety hazard at worst. An operator may have his fingers damaged and cut or even severed by the grinder in attempts to pull the guard out of contact with a work piece. On the other hand, the operator may have dangerous shavings or debris thrown into his or her face and eyes by an unguarded grinder blade or wheel. Not only are there personal risks to unguarded operation but safety restrictions and legal ramifications pursue from OSHA (Operational Safety and Health Administration) and an operator's ability to work for contracts requiring OSHA compliance.
Some conventional grinder guards include limiters configured to put boundaries on how far a grinder guard can retract and therefore allow less spring force and tension to a workpiece. Such limiters help alleviate the before mentioned issues in grinder guards but do not completely alleviate a retracting guard and the issues associated therewith. Therefore, and for other reasons not specifically described herein, there has been a long felt need in the market for a non-retracting grinder guard that does not interfere in an operator's work and craftsmanship.
A grinder guard assembly is disclosed for a grinder that includes a dialable grinder guard having indexed and chamfered holes adjacent to an inner ring thereof. An “L” edge on a portion of an outer circumference thereof forms a guard by retaining grinding debris and preventing outside intervention. The grinder guard assembly also includes an annulus forming a single member with an inside washer and an outside washer and a space there between configured to slidably retain the indexed grinder guard in a common plane with the washers. The annulus is axially attached to a hub of the grinder. The grinder guard assembly further includes torque sensitive conical pins or bumps mounted from the outside washer. The conical pins or bumps (protrusions) are configured to lock with the chamfered holes of the indexed grinder guard and retract therefrom based a torque on the indexed grinder guard relative to the annulus. The grinder guard assembly therefore adjustably locks into place relative to the grinder and may be dialed into various placements according to a torque force in balance with a spring force or torsion in opposition thereto.
A method for guarding a grinder is also disclosed. The disclosed method includes providing a dialable grinder guard defining a plurality of indexed and chamfered holes adjacent to an inner ring thereof. An “L” edge configured on a portion of an outer circumference thereof forms a guard by retaining grinding debris and preventing outside intervention. The disclosed method additionally includes axially attaching to a hub of the grinder an annulus forming a single member with an inside washer and an outside washer. A space between the washers retains the dialable grinder guard in a common plane with the washers. The disclosed method further includes dialing in a plurality of torque sensitive keepers mounted from the outside washer, the keepers configured to lock with the chamfered holes of the dialable grinder guard and retract therefrom based a torque on the indexed grinder guard relative to the annulus.
Other aspects and advantages of embodiments of the disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the disclosure herein.
Throughout the description, similar and same reference numbers may be used to identify similar and same elements in the several embodiments and drawings. Although specific embodiments of the invention have been illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the invention is to be defined by the claims appended hereto and their equivalents.
Reference will now be made to exemplary embodiments illustrated in the drawings and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Alterations and further modifications of the inventive features illustrated herein and additional applications of the principles of the inventions as illustrated herein, which would occur to a person of ordinary skill in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention.
Throughout the present disclosure, the term “torque sensitive” refers to the ability of the disclosure to sense the torque force necessary to twist or turn and dial the grinder guard into a locking position relative to the annulus which is clamped onto a grinder hub. The torque force necessary is just enough to urge the grinder guard from one locked position into another different locked position but also enough to overcome most operating forces on the grinder guard such as resulting from grinding debris and operator bumping motions thereto. Also throughout the present disclosure, the term “adjustable locking” refers to a locking mechanism that allows adjustments to various positions between locking into a semi-temporary placement for operation of a grinder. The grinder referred to in the present disclosure can be a portable handheld unit or it can be a table top fixed unit. The grinder guard assembly and device as disclosed operates and functions in the same and similar manner regardless of the status of the grinder. In fact, the disclosure may be equally and similarly applied to any circular or rotary power tool where protection from debris created by an abrasive wheel or cutting blade is found.
An embodiment of the disclosed grinder guard device is included wherein the torque sensitive keepers comprise a static frictional load against the chamfered holes of the dialable grinder guard 2. The static frictional load is less than a torque applied to the grinder guard relative to the grinder annulus to change a locked position of the grinder guard relative to the grinder. Additionally, or in the alternative, the torque sensitive keepers comprise a spring loaded pin having a spring load less than a torque applied to the grinder guard relative to the grinder annulus to urge a pin out from a locked position in the chamfered hole of the grinder guard.
An embodiment of the disclosure includes the annulus 4, separated from the washer 3 by a slot between ends 10a to 10b defined along a portion of the circumference of the annulus 4. The slot is configured to allow a compression of the annulus 4 around the axial hub of the grinder. A clamping device including parts 7a and 7b on the annulus 4 is separated from the outside washer 3 by the slot ends 10a to 10b. The clamping device is configured to frictionally and axially attach the annulus on the hub or boss of a grinder based on a mechanical pressure there between derived by the clamping device. The clamping device also comprises two opposing lips 7a and 7b, one on each of two sides formed in the annulus portion separated from the outside washer by the slot. A screwing fastener adjustably compresses the opposing lips together thus clamping the annulus ring on the hub of the grinder mechanism.
In an additional embodiment of the disclosure, the torque necessary to move an outer washer protrusion, pin or bump from a chamfered hole of the grinder guard comprises a nominal 10 ft-lbs to 15 ft-lbs torque force on the grinder guard with respect to the grinder annulus and grinder hub, plus or minus a 10% manufacturing tolerance. This torque force is usually provided by the operator of the grinder in order to adjust the guard to a position relative to the grinder that provides him or her the maximum protection from grinder debris. The torque necessary to dial in or adjust the grinder guard 2 into a locked position with respect to the grinder annulus is based on a helical adjustment of the protrusion penetration relative to a chamfered hole in the grinder guard 2. The helical adjustment may be via an adjusting plug or screw which puts pressure directly or indirectly on a protrusion spring or on a torsional relation of the grinder guard to the inside and outside washers 1 and 3. Additionally, the helical adjustment of a spring coil length acting on the protrusion relative to a chamfered hole in the grinder guard varies the torque force on the grinder guard with respect to the grinder annulus and therefore the grinder hub.
Disclosed in another embodiment of the present disclosure, the torque sensitive protrusions 5 referred also herein as 5a, 5b and 5c comprise a spring loaded cone 18 or pin having a spring load less than a torque applied to the grinder guard 2 relative to the grinder annulus 4 and the grinder to change a locked position of the grinder guard 2 relative to the grinder. Optionally, the torque sensitive protrusions 5 comprise bumps having a static frictional load less than a torque applied to the grinder guard 2 relative to the grinder annulus 4 and the grinder to change a locked position of the grinder guard 2 relative to the grinder and grinder hub. Yet still, the torque sensitive protrusions 5 comprise a spring loaded ball bearing having a spring load less than a torque applied to the grinder guard 2 relative to the grinder annulus 4 and the grinder to change a locked position of the grinder guard 2 relative to the grinder and grinder hub to which the assembly or device is attached. That is, a torque force in the plane of the grinder guard 2 and the washers 1 and 3 urges the cone pin or the ball bearing out of the chamfered hole in the grinder guard so that an operator can dial in a new placement of the grinder guard 2 in the index of holes relative to the annulus 4 for various jobs and needs the operator may have.
The torque force is sufficient to urge the cone pin 18 to retract from the chamfered hole 19. The torque sensitive spring 17 supplies enough counter force to the movement of the cone pin to offset the retracting motion and allow the cone pin to lock into subsequent index chamfered hole based on the operator. Therefore, the static friction between the cone pin and the chamfered hole is overcome by the torque force applied thereto but is subsequently itself overcome by the spring force or spring constant of the torque sensitive spring. This interplay of forces allows a new locking formation in a subsequent chamfered hole chosen by the operator applying the torque force. Therefore, the grinder guard assembly and device is sensitive to a torque force for dialing in a locking position of the grinder guard relative to the annulus clamped on the hub of the grinder.
The spring force enables the dialing and locking motion to occur over and over again. However, the spring constant of the torque sensitive spring is not greater than the force resulting in retracting the cone pin from the chamfered hole in the grinder guard 2. A bump protrusion implementation may draw spring force from the torsional movement of the inside and outside washers against the grinder guard 2. A ball bearing implementation may draw spring force from a torque sensitive spring between the ball bearing in the chamfered hole and the helical plug.
An embodiment of the disclosed method for guarding a grinder comprises urging a torque sensitive keeper, having a spring load less than a torque applied to the grinder guard relative to the grinder annulus and the grinder, out from a locked position in the chamfered hole of the grinder guard. The embodied method may further comprise clamping the annulus around the axial hub of the grinder via a separating slot defined between the outside washer along a portion of the circumference of the annulus, the slot configured to allow a compression of the annulus around the axial hub of the grinder.
The non-obvious and novel features and advantages of the present disclosure are not limited to a handheld or table top grinder, abrasive blades or circular saws but may also be used in other types of rotary tools for piping, commercial and residential construction and the like. The present disclosure satisfies the long felt need in the market place for an adjustable yet locking grinder guard. The present disclosure is very portable, can be small or large, is effective and easy to use and only requires a reasonable torque force relative to a fixed grinding reference. It may be used for large volume industrial piping or in the field where it is more practical to carry a hand held grinder.
Although the operations of the method(s) herein are shown and described in a particular order, the order of the operations of each method may be altered so that certain operations may be performed in an inverse order or so that certain operations may be performed, at least in part, concurrently with other operations. In another embodiment, instructions or sub-operations of distinct operations may be implemented in an intermittent and/or alternating manner.
Notwithstanding specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the invention is to be defined by the claims and their equivalents included herein or by reference to a related application.
