Choon Nang Electrical Appliance Mfy., Ltd.

Kwok Kwong Ho

Tat Nin Lui

Heung Ching Ng

A battery pack for a power tool includes a casing housing rechargeable cells. A receiving bay in the casing receives slide-in parts of the power tool and of a recharging stand, to retain the battery pack. A pair of primary electrical contacts is located in or adjacent the receiving bay. A recess opens into the receiving bay. A supplementary electrical contact is located within the recess, and a user-manipulable catch is also located in the recess alongside the supplementary contact. That is, a single recess houses both the supplementary contact and the mechanical catch. The supplementary contact is usable when recharging the battery to relay battery temperature information to a recharging stand, but has no function when the battery pack is attached to the power tool. The catch, useful in retaining the battery pack on the power tool, has no function with the recharging stand.

Rechargeable battery pack

A drill bit capable of axial cutting as well as side cutting, having a generally cylindrical elongate body with a bit diameter, includes a frontmost drilling end for axial cutting, a cutting section extending from the drilling end for side cutting, and a shank extending from the cutting section. The cutting section is helically cut at a helix angle of substantially 15&deg;&plusmn;2&deg; to form one pair of diametrically opposite helical flutes whose outermost edges are sharpened to form respective cutting edges, arranged around a solid central core whose diameter is substantially directly proportional to the bit diameter. The length of the cutting edges in the axial direction of the drill bit body is calculated according to the formula: Cutting Edge&equals;Bit Diameter&times;&pgr;&times;C /Tan (Helix Angle), C being a constant in a range from 0.85 to 0.90.

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Hong Kong, China

Kwok Kwong Ho