Sewing machine cutting mechanism

Claim 2

A sewing machine comprising a cutting station disposed in a feed path of material to be sewed, a power operated material feeding apparatus for feeding material along said feed path, a manually operable change speed device connected to the feeding apparatus for varying its operating speed, a selectively actuatable override control mechanism operative for operating the change speed device, and sensing means responsive to the presence of material at a predetermined point in said feed path for actuating the override control mechanism and automatically governing the operation of the change speed device to positively control the advance of material through the cutting station.

Claim 3

The machine of claim 1 wherein the change speed device includes power operated drive means drivingly connected to the material feeding apparatus and a manually movable variable speed control operatively connected to the power operated drive means.

Claim 4

The machine of claim 2 wherein the override control mechanism includes an actuating cylinder and an extensible and retractable piston rod operated by the cylinder, and a link connected to the piston rod for engaging the manually movable variable speed control and automatically moving it to a preselected operating position responsive to actuation of the piston rod to one of its extended and retracted positions, the piston rod upon being actuated to said one position constraining the manually movable variable speed control against manual operation. 4, The machine of claim 3 further including a solenoid operated valve actuated by the sensing means for operating the actuating cylinder, and means responsive to the completion of a cutting operation for de-energizing the valve and deactivating the cylinder to return the change speed device to manual operation.

Claim 5

The machine of claim 3 further including adjustment means for varying the displacement of the link upon actuation of the piston rod for selectively establishing the operating position of the speed control for preselecting the operating speed of the material feeding apparatus.

Claim 6

The machine of claim 2 wherein the power operated drive means includes a clutch-brake unit connected to the manually movable variable speed control for driving the material feeding apparatus and, alternatively, for applying a braking action to stop the material feeding apparatus, and wherein the override control mechanism drivingly engages the manually movable variable speed control upon actuation by the sensing means to automatically override manual control by an operator to establish positive automatic control over the advance of material through the cutting station.

Claim 7

The machine of claim 6 including adjustment means for selectively establishing the positioning of the manually movable variable speed control upon its being engAged by the override control mechanism for presetting the operating speed of the material feeding apparatus upon actuation of the override control mechanism.

Claim 8

The machine of claim 7 wherein the adjustment means has a range of adjustment for varying the speed of the material feeding apparatus between a maximum operating speed and complete stoppage.

Claim 9

The machine of claim 1 wherein a cutting mechanism is operatively mounted in said feed path of material for operation synchronized with the passage of material along said feed path, wherein the sensing means comprises a photoelectric device disposed in said feed path of material upstream of the cutting mechanism and operable in response to passage of material past the photoelectric device, and wherein photoelectrically responsive means are provided for actuating the override control mechanism.

Claim 10

The machine of claim 9 further including a second photoelectric device disposed in said feed path of material downstream of the cutting mechanism and means operable in response to passage of material past the second photoelectric device for deactivating the override control mechanism.

Claim 11

The machine of claim 9 further including knife operating means automatically actuatable by the photoelectric device for operating the cutting mechanism to cut material in timed relation to passage of such material through the cutting station.

Claim 12

The machine of claim 1 wherein the cutting station includes a cutting mechanism for severing material and power operated means for operating the cutting mechanism, and wherein actuating means are provided for actuating the power operated means in response to passage of material through the cutting station in synchronism with the actuation of the override control mechanism.

Claim 13

The machine of claim 12 wherein actuation of the override control mechanism by the sensing means operates the change speed device to automatically terminate operation of the material feeding apparatus to effect precise severing of the material in a stationary condition at the cutting station.

Claim 14

The machine of claim 12 wherein actuation of the override control mechanism by the sensing means operates the change speed device to automatically effect operation of the material feeding apparatus at a controlled given speed for continued feeding of material through the cutting station in timed relation to operation of the cutting mechanism.