| 摘要 |
A sewing machine comprises a stepped cutting device for stepwise cutting of the edges of the material parallel to the seam. The device has two upper blades which move vertically and a lower blade (18) which co-operates with one of the upper blades. The lower blade is mounted on a blade carrier (20) which is parallel to the sewing plate (10) of the sewing machine and which can be adjusted transversely to the stitching direction. An actuator (22) inserts the lower blade between the layers of fabric (32, 34). The needle plate (10) is provided near the cutting point with an opening connected to a suction device. A nozzle (26, 28) which can be connected by an actuating device (38, 36) to a compressed air source (25) is arranged above the needle plate (10) so that its axis (30) is directed toward the edges of the fabric at the point where the lower blade (18) is inserted between the layers of fabric. A control device (24) for the actuator (22) and the actuating device (38, 36) are mutually coupled so that the air jet leaving the nozzle (26, 28) reaches the edges of the fabric immediately before the lower blade (18) is inserted. |
