Overlock sewing machine

An overlock sewing machine comprising:

• an upper blade configured such that it can be moved between an interlock position at which it is driven in an upper-lower direction together with a rotation of a main shaft and a retraction position to which it is to be retracted downward from the interlock position;
• a rod configured such that it extends in a direction that is orthogonal to an axial direction of the main shaft, and arranged such that one end portion is coupled to the main shaft by an eccentric cam, which allows the rod to be swung by a driving force applied by the main shaft;
• a swing member supported by a support shaft arranged in parallel with the axial direction of the main shaft such that it can be swung, coupled to the upper blade via another member, comprising a fitting portion configured such that it can be fitted into a fitting target portion provided to the other end portion of the rod, and configured such that, when the fitting portion is fitted into the fitting target portion, the swing member is reciprocally swung accompanying a swinging of the rod according to a rotation of the main shaft, so as to drive the upper blade in the upper-lower direction when the upper blade is set to the interlock position;
• an interlock switching mechanism configured to operate to switch a state to an interlock state, in which the fitting target portion is fitted into the fitting portion so as to allow the upper blade to be driven together with the main shaft, or otherwise an interlock release state, in which a fitting state between the fitting target portion and the fitting portion is released so as to release the interlock state;
• a position switching mechanism configured to operate such that a position of the upper blade is switched to the retraction position or otherwise the interlock position;
• and
• an operating shaft configured such that it can be slid between a first position and a second position to which it is to be slid from the first position in the axial direction, and such that, by turning the operating shaft, the interlock switching mechanism and the position switching mechanism are operated,
• wherein the interlock switching mechanism comprises:
• a rotor provided such that it can be rotated together with the operating shaft as a single unit;
• an interlock switching member coupled to the fitting target portion, including an engagement portion protruding toward the rotor side, and configured to operate according to the rotation of the rotor so as to switch the state to the interlock state or otherwise the interlock release state;
• and
• a first engagement target portion formed in the rotor such that it can be engaged with the engagement portion,
• wherein, in the interlock state, upon setting the operating shaft to the first position, the engagement portion is engaged with the first engagement target portion so as to restrict the rotation of the operating shaft,
• and wherein, upon sliding the operating shaft to the second position, the engagement state between the engagement portion and the first engagement target portion is released so as to enable the rotation of the operating shaft.