Abstract: A method for producing s connecting rod, wherein the vicinity of the bottom portion of a notch, which is planed to be broken in a pre-formed article for the connecting rod, is irradiated with a laser light, a plasma or the like, and when the irradiated bottom portion is allowed to cool in air, an austenite structure is transformed into a martensite structure, which results in the formation of a martensite portion in the vicinity of the bottom portion of a notch.

Abstract: A casing houses therein a laser oscillator for emitting a laser beam, and a tubular head is disposed coaxially with the laser oscillator and coupled to the casing. The laser beam emitted from the laser oscillator is converged by a condenser lens mounted on the head, and then reflected in a direction substantially perpendicular to the axis of the head by a reflecting mirror that is disposed in the head. The reflected laser beam is applied substantially perpendicular to the inner circumferential surface of a workpiece, forming grooves therein with the heat of the laser beam.

Abstract: A cracking apparatus has a pair of spreaders to be placed in a joint hole defined in a larger end of a connecting rod, a wedge that is pressed in between the spreaders, a preloading mechanism for imparting a preload to the wedge, and a loading mechanism for imparting an impact load to the wedge in the direction in which the wedge is pressed, by energizing a rotational drive source and transmitting rotational drive power from the rotational drive source through a shaft connected to the wedge, after the preload has been applied to the wedge by the preloading mechanism.

Abstract: When a rotary drive source on a body is energized, a drive pulley is rotated, and the rotary drive power from the drive pulley is transmitted to a driven pulley by a drive power transmitting belt. A slotting mechanism integrally coupled to the driven pulley is rotated and inserted into a larger end hole defined in a connecting rod. A cutting plate of the slotting mechanism forms a first slot having a substantially rectangular concave cross section in the inner circumferential surface of the larger end hole and then a second slot having a substantially rectangular concave cross section in the inner circumferential surface of the larger end hole at a position facing the first slot across the axis of the connecting rod. The first and second slots have a symmetrical shape.

Abstract: A preload is applied to a wedge pressed in between a pair of spreaders by a preloading mechanism to press the spreaders against an inner surface of a joint hole defined in a larger end of a connecting rod. While the spreaders are pressed against the inner surface of the joint hole, a movable table with weights placed thereon is caused to drop into impingement against a flange coupled to an end of a shaft. The shaft is pulled downwardly to apply an impact load to the wedge, which is coupled to the shaft, in the direction in which the wedge is pressed in, thereby fracturing the larger end into a cap and a rod.

Abstract: When a rotary drive source on a body is energized, a drive pulley is rotated, and the rotary drive power from the drive pulley is transmitted to a driven pulley by a drive power transmitting belt. A slotting mechanism integrally coupled to the driven pulley is rotated and inserted into a larger end hole defined in a connecting rod. A cutter of the slotting mechanism forms a first slot having a substantially V-shaped cross section in the inner circumferential surface of the larger end hole and then a second slot having a substantially V-shaped cross section in the inner circumferential surface of the larger end hole at a position facing the first slot across the axis of the connecting rod. The first and second slots have a symmetrical shape.