A needle plate attaching/detaching mechanism includes: a needle plate fixing portion rotatably provided below a needle plate mounted on a sewing machine main body, and movable between a fixed position fixing the needle plate to the sewing machine main body and a non-fixed position where the fixing is released; a driving gear jointly rotatably coupled to the needle plate fixing portion; a transmission mechanism switchable between a transmission state transmitting driving force from a motor to the driving gear and a disconnection state disconnecting the transmission; and an operating member including a manual gear transmitting manual operating force to the driving gear. When the operating member is non-operating, the transmission mechanism is set to the transmission state, and the manual gear is disconnected from the driving gear. In the operating state, the operating member switches the transmission mechanism from transmission to disconnection, and the manual and driving gears are coupled.

In a sewing machine, a plurality of needle plate holes are formed in a needle plate. The needle plate holes are arranged at positions respectively corresponding to a plurality of blade-side rotation positions of a cutwork blade. In this manner, the needle plate hole is formed in a shape corresponding to a shape of a blade portion, and a direction of the needle plate hole can match a direction of the blade portion that is arranged above to face the needle plate hole. Specifically, a linear hole-side cutting surface corresponding to a blade-side cutting surface of the blade portion is formed in the needle plate hole, and the blade-side cutting surface and the hole-side cutting surface can be arranged to face each other in a direction orthogonal to both the surfaces in a plan view.

In a sewing machine, a plurality of needle plate holes are formed in a needle plate. The needle plate holes are arranged at positions respectively corresponding to a plurality of blade-side rotation positions of a cutwork blade. In this manner, the needle plate hole is formed in a shape corresponding to a shape of a blade portion, and a direction of the needle plate hole can match a direction of the blade portion that is arranged above to face the needle plate hole. Specifically, a linear hole-side cutting surface corresponding to a blade-side cutting surface of the blade portion is formed in the needle plate hole, and the blade-side cutting surface and the hole-side cutting surface can be arranged to face each other in a direction orthogonal to both the surfaces in a plan view.

In feed dog mounting/unmounting mechanism, lever is slidably provided to feed base in the front-rear direction, and is forced backward by a lever force-applying spring. Upon sliding lever rearward, fixing target portion of feed dog 22 is fixedly held by base-side fixing portion of feed base and lever-side fixing portion of lever arranged in the front-rear direction. Stopper is provided to feed base so as to be movable in the upper-lower direction, and holds lever. When feed dog is mounted, stopper is pressed downward by feed dog, which moves stopper so as to allow lever to slide. With this, lever is slid due to force applied by the lever force-applying spring, thereby allowing fixing target portion to be held, interposed between base-side fixing portion and lever-side fixing portion.

In feed dog mounting/unmounting mechanism, lever is slidably provided to feed base in the front-rear direction, and is forced backward by a lever force-applying spring. Upon sliding lever rearward, fixing target portion of feed dog 22 is fixedly held by base-side fixing portion of feed base and lever-side fixing portion of lever arranged in the front-rear direction. Stopper is provided to feed base so as to be movable in the upper-lower direction, and holds lever. When feed dog is mounted, stopper is pressed downward by feed dog, which moves stopper so as to allow lever to slide. With this, lever is slid due to force applied by the lever force-applying spring, thereby allowing fixing target portion to be held, interposed between base-side fixing portion and lever-side fixing portion.

In a sewing machine, a plurality of needle plate holes are formed in a needle plate. The needle plate holes are arranged at positions respectively corresponding to a plurality of blade-side rotation positions of a cutwork blade. In this manner, the needle plate hole is formed in a shape corresponding to a shape of a blade portion, and a direction of the needle plate hole can match a direction of the blade portion that is arranged above to face the needle plate hole. Specifically, a linear hole-side cutting surface corresponding to a blade-side cutting surface of the blade portion is formed in the needle plate hole, and the blade-side cutting surface and the hole-side cutting surface can be arranged to face each other in a direction orthogonal to both the surfaces in a plan view.

In a sewing machine, a plurality of needle plate holes are formed in a needle plate. The needle plate holes are arranged at positions respectively corresponding to a plurality of blade-side rotation positions of a cutwork blade. In this manner, the needle plate hole is formed in a shape corresponding to a shape of a blade portion, and a direction of the needle plate hole can match a direction of the blade portion that is arranged above to face the needle plate hole. Specifically, a linear hole-side cutting surface corresponding to a blade-side cutting surface of the blade portion is formed in the needle plate hole, and the blade-side cutting surface and the hole-side cutting surface can be arranged to face each other in a direction orthogonal to both the surfaces in a plan view.

In a needle plate, a needle plate hole is configured to include a hole-side cutting side that cuts a cutting target object together with a blade portion, and a relief side that allows a cut portion of the cutting target object to escape. Specifically, the needle plate hole has the hole-side cutting side that shears the cutting target object together with a blade-side cutting side of the blade portion, and the relief side that forms a gap between the blade portion to be inserted and the relief side. In this manner, in the former stage of cutting processing, the cutting target object can be cut by the hole-side cutting side and the blade-side cutting side.

In a needle plate, a needle plate hole is configured to include a hole-side cutting side that cuts a cutting target object together with a blade portion, and a relief side that allows a cut portion of the cutting target object to escape. Specifically, the needle plate hole has the hole-side cutting side that shears the cutting target object together with a blade-side cutting side of the blade portion, and the relief side that forms a gap between the blade portion to be inserted and the relief side. In this manner, in the former stage of cutting processing, the cutting target object can be cut by the hole-side cutting side and the blade-side cutting side.

An overlock sewing machine includes an operating shaft that is slidable between first and second positions, and configured such that interlock switching and position switching mechanisms are operated when it is turned. The interlock switching mechanism includes a rotor that is rotatable together with the operating shaft as a single unit, an interlock switching member, and a first engagement target portion formed in the rotor. In the interlock state, setting the operating shaft to the first position engages an engagement portion of the interlock switching member with the first engagement target portion, which restricts operating shaft rotation. Sliding the operating shaft to the second position releases the engagement state between the engagement and first engagement target portions, enabling rotation of the operating shaft.