ANGLE GRINDER INCLUDING NON-REMOVABLE GUARD

An angle grinder includes an output shaft defining a rotational axis, a housing from which the output shaft extends, and a flange coupled to the housing and surrounding the output shaft. The angle grinder further includes a first circumferential groove defined between the flange and the housing, a first array of radially outward-extending slots in the flange and in communication with the first circumferential groove, and a keyway defined in the housing. The keyway is positioned inline with a first of the radially outward-extending slots in the first array. The angle grinder further includes a guard with a second array of radially inward-extending projections and a key positionable within the keyway. The radially inward-extending projections are received in the radially outward-extending slots. The key is able to close the first radially outward-extending slot in the first array to prevent removal of the guard from the housing.

FIELD OF THE INVENTION

The present invention relates to hand-held power tools, and more particularly to angle grinders.

BACKGROUND OF THE INVENTION

Power tools, such as hand-held angle grinders, include rotating abrasive tool elements, or abrasive discs, that create debris during operation on a workpiece. Such angle grinders typically include a guard partially surrounding the abrasive disc to shield a user of the angle grinder from such debris. However, such guards are typically removable to unshroud the entire outer periphery of the abrasive disc for a grinding operation.

SUMMARY OF THE INVENTION

The invention provides, in one aspect, an angle grinder including an output shaft defining a rotational axis, a housing from which the output shaft extends, and a flange coupled to the housing and surrounding the output shaft. The angle grinder also includes a first circumferential groove defined between the flange and the housing, a first array of radially outward-extending slots in the flange and in communication with the first circumferential groove, and a keyway defined in the housing. The keyway is positioned inline with a first of the radially outward-extending slots in the first array. The angle grinder further includes a guard with a second array of radially inward-extending projections and a key positionable within the keyway. The second array of radially inward-extending projections is received in the first array of radially outward-extending slots. The key able to close the first radially outward-extending slot in the first array to prevent removal of the guard from the housing.

The invention provides, in another aspect, an angle grinder including an output shaft defining a rotational axis, a housing from which the output shaft extends, and a flange coupled to the housing and surrounding the output shaft. The angle grinder also includes a first circumferential groove defined between the flange and the housing, a first array of radially outward-extending slots in the flange and in communication with the first circumferential groove, and a guard including a second array of inward-extending projections. The inward-extending projections of the guard are configured to be received in the first array of the radially outward-extending slots. The angle grinder further includes a first stop disposed on the housing, and a second stop formed on the guard and engageable with the first stop. The second stop engages the first stop to prevent the re-alignment of the second array of radially inward-extending projections with the first array of radially outward-extending slots, which prevents the removal of the guard from the housing.

The invention provides, in another aspect, an angle grinder including an output shaft defining a rotational axis, a housing from which the output shaft extends, a guard coupled to the housing and partially surrounding the output shaft, and a guard locking flange coupled to the housing. The guard locking flange is permanently affixed to the housing and configured to axially retain the guard to the housing.

DETAILED DESCRIPTION

FIG.1illustrates a hand-held power tool, such as an angle grinder100, including a housing104defining, collectively, a motor housing portion114and a gear case portion116mounted to a front end of the motor housing portion114. In the illustrated embodiment, the gear case portion116includes a gear case118and a gear case cover120fastened to the gear case118with a plurality of gear case fasteners121. The angle grinder100also includes an output shaft122extending from the gear case portion116along a rotational axis126that is perpendicular to a longitudinal axis128defined by the motor housing portion114. The output shaft122is driven by a motor (not shown) positioned within the motor housing portion114and a gear train (also not shown) is positioned within the gear case portion116for transferring torque from the motor to the output shaft122. A grinding or abrasive disc (not shown) can be mounted to the output shaft122for co-rotation therewith about the rotational axis126.

With reference toFIG.2, the gear case cover120includes a flange130extending therefrom and encircling the rotational axis126. In some embodiments, the gear case portion116and motor housing portion114may be integrally formed as a single piece, with the flange130also being an integral piece of the housing104. In other embodiments, the flange130may be a separate component and may be selectively coupled to the housing104. The flange130includes an array of six radially outward-extending slots138and a keyway139coinciding or inline with a first of the slots138. The gear case cover120defines a circumferential groove134below and adjacent the flange130, such that the slots138are in communication with the circumferential groove134. One of the slots138is has a width greater than the remaining slots138and is therefore used as an alignment slot142as explained in detail below. In other embodiments of the angle grinder100, the flange130may include more or fewer slots138. In addition, the keyway139is shaped to receive a key141, which is used for axially retaining a guard146to the gear case cover120, as explained in further detail below.

With continued reference toFIG.2, the guard146partially surrounds the abrasive disc (not shown) when the disc is mounted to the output shaft122. And, the guard146is rotatable relative to the gear case cover120to adjust the orientation of the guard146relative to the housing104and expose different regions of the abrasive disc needed for a grinding operation. The guard146includes an array of six radially inward-extending projections150and five apertures155positioned radially about guard146. One of the projections150has a width greater than the remaining projections and is therefore used as an alignment projection158to be received within the alignment slot142in the flange130. The projections150on the guard146are aligned with, and therefore receivable through, the slots138in the flange130when the alignment projection158is aligned with the alignment slot142. After inserting the projections150within the slots138, the guard146is lowered until the projections150reach the circumferential groove134. Thereafter, the guard146can be rotated about the rotational axis126to misalign the projections150from the slots138, thereby axially securing the guard146to the gear case cover120. The guard146is thereby removable from the circumferential groove134only when the alignment projection158is re-aligned with the alignment slot142, at which time the remainder of the projections150will become re-aligned with the respective slots138.

Referring toFIG.3, the angle grinder100further includes a latch plate162for rotationally securing the guard146into a desired orientation relative to the gear case cover120. The latch plate162includes an actuating portion170and a detent member174. A compression spring182is positioned between a spring seat186on the gear case cover120and biases the detent member174toward the guard146. In the illustrated embodiment, the spring seat186is a recess and the compression spring182is positioned within the spring seat186. In alternative embodiments, the spring seat may be a post and the compression spring182may be positioned and seated around the post. The detent member174is receivable in one of the five apertures155in the guard146to rotationally secure the guard146relative to the gear case cover120. The latch plate162is biased by the spring182to position the detent member174in one of the apertures155upon installation of the guard146onto the gear case cover120as described above. The detent member174is removed from one of the apertures155in the guard146by applying a force to the actuating portion170of the latch plate162directed away from the guard146. The applied force removes the detent member174from one of the apertures155, after which time the guard146is free to rotate about the rotational axis126to a different rotational position relative to the gear case cover120. Upon releasing the actuating portion170, the spring182rebounds and pushes the detent member174back toward the guard146, thereby positioning the detent member174into the next aperture155that it encounters as rotation of the guard146continues to a desired position.

Referring toFIGS.4and5, when installed in the keyway139, the key141prevents the guard146from being removed from the gear case cover120. In practice, the guard146is installed as detailed above and then rotated to a position where none of the projections150block the keyway139, as shown inFIG.4, at which instance the keyway139is aligned with a slot between two adjacent projections150. When the keyway139is unobscured, the key141can be inserted into the keyway139. Once installed in the keyway139, the key141can be secured to the gear case cover120via a fastener or a pin (not shown) to make it difficult for unauthorized users to remove the key141. The fastener or pin (not shown) is installed in a hole184in the gear case cover120(FIG.5) with a tool (e.g., a hex driver) and secured into an aligned, corresponding hole188in the key141(FIG.4). In some embodiments, the hole184is oriented transverse to the rotational axis126. When the key141is installed, one of the slots138is blocked by a flange portion190of the key141(FIG.5), which prevents any one of the projections150from exiting through its designated slot138. Therefore, the guard146is prevented from being removed from the gear case cover120at any time. However, the rotational adjustment of the guard146is unhindered as the key141includes a circumferential groove192aligned with the circumferential groove134in the gear case cover120with an equal thickness as the circumferential groove134. As such, the guard146can freely rotate when the detent member174is removed from the apertures155.

An alternate embodiment of the angle grinder500is shown inFIGS.6A,6B, and7, with like features as the angle grinder100shown inFIGS.1-5being shown with like reference numerals. In the illustrated embodiment, the guard146is still rotatable about the rotation axis126, but not removable. The guard146is installed in a similar fashion to the angle grinder100, as described above. However, the key541does not include a hole, but instead includes a plurality of indents543against which a corresponding plurality of fasteners (e.g., set screws548) are clamped using a tool (e.g., a hex driver). Each of the indents543includes an angled surface544and an adjacent bottom surface545, as shown inFIG.7. When the key541is installed in a keyway539, the indents543are aligned to a plurality of holes584formed on a gear case cover520. The holes584are threaded and each receive a set screw548that is inserted into one of the indents543. In the illustrated embodiment, the set screws548have a conical end547. When the key541is not fully installed, the conical end547of the set screw548contacts the angled surface544. As the set screw548is further threaded, the conical end547moves along the angled surface544, which in turn moves the key541further into the keyway539. The key541is considered fully installed when it contacts a bottom550of the keyway539and the conical ends547of the set screws548contact both the bottom surface545and the angled surface544.

FIGS.8A and8Billustrate an alternate embodiment of a key541B and an alternate embodiment of a gear case cover520B. The key541B includes a single indent543, which can receive one set screw548. The set screw548can be received through a hole584in the gear case cover520B.

An alternate embodiment of an angle grinder300is shown inFIGS.9A-9B, with like features as the angle grinder100shown inFIGS.1-5being shown with like reference numerals. In the illustrated embodiment, the guard146is still rotatable but not removable. The guard146is installed in a similar fashion as detailed above with the angle grinder100. However, the guard146is non-removable from the gear case cover120due to interaction between a first stop393and the guard146. As shown inFIG.9B, the first stop393has an L-shaped cross-section and is attached to the gear case cover120with a fastener or a pin (not shown) that is not easily removable. When installed, a second stop394formed on the guard146, such as a radially outward extending projection, contacts a notch395defined on the first stop393to prevent rotation of the guard146past a certain degree. As a result, the guard146cannot be removed from the gear case cover120, because the projections150are not permitted to align with their respective slots138.

An alternate embodiment of a gear case cover420is shown inFIG.10, with like features as the gear case cover120shown inFIGS.1-5being shown with like reference numerals. In the illustrated embodiment, the guard146is axially retained by a guard-locking flange498. The guard locking flange498retains the guard146to the gear case cover420by connecting to a hub499on the gear case cover420through a pair of reverse threads, a press fit, a roll pin, or a combination of the three. In the illustrated embodiment, the guard-locking flange498includes a set of male reverse threads (not shown), while the hub499of the gear case cover420includes a set of corresponding female threads (not shown). If the guard locking flange498is installed onto the hub499of the gear case cover420, the guard locking flange498cannot be removed and the rotatable guard146is axially retained. In another embodiment, the guard-locking flange498is press-fitted to the hub499of the gear case cover420. Once press fitted, the guard-locking flange498cannot be removed and therefore axially retains the guard146.

FIG.11illustrates an alternate embodiment of a gear case cover620and an alternate embodiment of a guard locking flange698. The gear case cover620and the guard locking flange698include like features as the gear case cover420and the guard locking flange498shown inFIG.10being shown with like reference numerals. In the illustrated embodiment, the guard146is axially retained by the guard locking flange698. To axially secure the guard146, the guard146is first installed in a circumferential groove634. Next, the guard locking flange698is press-fit into the gear case cover620over the guard146, thus permanently affixing the guard locking flange698to the housing of the angle grinder. Once the guard locking flange698is fully installed into the gear case cover620, a pin652is press-fit through a first pin opening654in the gear case cover620and then through a second pin opening656in the guard locking flange698. The press-fit pin652subsequently prevents the removal of the guard locking flange698and the guard146, while still allowing for rotation of the guard146in the circumferential groove634. In other embodiments, the gear case cover620and the guard locking flange698may be threaded together before the pin652is inserted.