Abstract: A circular saw blade has a frame, which includes a plurality of recesses and a groove. The circular saw blade also has at least two arc-shaped blade strips, each having a plurality of sawteeth formed on the outer rim and at least one bump and a protruding piece on the inner rim, such that each bump is configured for mating with its corresponding recess on the frame and the protruding piece is formed extending along the circumference of the inner rim for insetting into the groove of the frame.

Abstract: An electric saw device includes a first saw blade and a second saw blade. The first and the second saw blades are respectively driven by a small transmission shaft and a large transmission shaft to rotate in opposite directions. A round rib is disposed on an inner end surface of the first saw blade, and at least three recessed holes are arranged in a top end surface of the round rib at equal angle intervals. A steel ball is accommodated in each of the recessed holes, and protrudes out of the recessed hole. Protruding ends of the steel balls urge against an inner surface of the second saw blade, so as to limit a distance between the first saw blade and the second saw blade, and form a rolling friction when the first and the second saw blade rotate in the opposite directions.

Abstract: An electric saw device having two saw blades being arranged for allowing the two saw blades to be driven to rotate in opposite directions. The two saw blades are respectively formed with circular grooves on their inner surfaces at positions corresponding to each other while enabling the centers of the two circular grooves to aligned with the rotation axes of corresponding saw blades. The electric saw device has a plurality of steel balls, each being sandwiched between the two saw blades while insetting into the circular grooves simultaneously, by that the saw blades are separated from each other by a specific interval. Accordingly, when the two saw blades are rotating in opposite direction, each of the steel balls is acting as a roller bearing for maintaining the two saw blades to be properly separated from each other, and thus preventing the two saw blades from overheating and softened by friction.

Abstract: A circular saw blade with changeable blade strips, comprising: a frame, configured with a plurality of recesses and a groove formed on the circumferential surface of the frame; at least two arc-shaped blade strips, each having a plurality of sawteeth formed on the outer rim thereof while providing the inner rim thereof to be formed with at least one bump and a protruding piece in a manner that each bump is configured for mating with its corresponding recess on the frame and the protruding piece is formed extending along the circumference of the inner rim for insetting into the groove of the frame; and a plurality of bolts; wherein, the at least two blade strips are fixed to the circumference of the frame by screwing the plural bolts through the corresponding via holes on the protruding piece and then into their corresponding screw holes on the frame.