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 to be rotated so as to operate the interlock switching mechanism and the position switching mechanism,
• wherein the position switching mechanism comprises:
• a first switching portion provided such that it can be rotated together with the swing member as a single unit;
• a second switching portion provided on a reverse swing side of the swing member with respect to the first switching portion;
• and
• a pressing portion provided at a position that is eccentric with respect to the operating shaft such that it can be rotated together with the operating shaft as a single unit, and configured to be capable of pressing the first switching portion and the second switching portion,
• wherein, when the interlock state is set and the upper blade is set to the interlock position, upon turning the operating shaft toward one side around the axis of the operating shaft, the interlock switching mechanism displaces the other end portion of the rod so as to set the interlock release state, and the pressing portion presses the first switching portion such that the first switching portion swings the swing member toward a forward swing side, which moves the upper blade to the retraction position,
• and wherein, when the interlock release state is set and the upper blade is set to the retraction position, upon turning the operating shaft toward the one side around the axis of the operating shaft, the pressing portion presses the second switching portion such that the second switching portion swings the swing member toward the reverse swing side, which moves the upper blade to the interlock position, and the interlock switching mechanism displaces the other end portion of the rod so as to set the interlock state.