Auxiliary feed mechanism for sewing machines

In combination with a sewing machine having a motor means, a stitch forming instrumentality driven by said motor means, means for advancing a workpiece to said stitch forming instrumentality, control means for actuating said machine at timed intervals, and an auxiliary feed mechanism means comprising:

• feed roller means;
• drive means associated with said feed roller means for moving same;
• sensing means for producing a first signal representative of the speed of said drive means;
• and
• an electrical circuitry means comprising:
• first operative means responsive to actuation by said control means and operable to actuate said drive means at a first predetermined speed, including means for producing a second signal representative of said first predetermined speed;
• second operative means responsive to actuation by said control means and operable to drive said drive means at a second predetermined speed including means for producing a third signal representative of said second predetermined speed;
• means adapted to receive and compute the difference between said first signal and said second or third signal including means operative to influence actuation of said drive means according to the difference in values therebetween.

In combination with a sewing apparatus having various operating parameters, an auxiliary feed mechanism means comprising, a feed roller means, a motor means operatively coupled with said feed roller means for driving the latter at various speeds, and an arrangement for controlling the speed of the motor means in accordance with a particular operating parameter of said sewing apparatus comprising:

• first signal furnishing means furnishing, as a function of one operating parameter of said sewing apparatus, a first signal signifying the desired feed rate of said workpiece during said one operating parameter;
• second signal furnishing means furnishing a signal signifying the speed of said motor means;
• third signal furnishing means furnishing as a function of a second operating parameter of said sewing apparatus, a second signal signifying the desired feed rate of said workpiece during said second operating parameter;
• and
• means connected to said first, second and third signal furnishing means for comparing the first or second signal means against the signal signifying the speed of said motor means and furnishing a speed signal to said motor means signifying the difference between said signal signifying the speed of said motor means and said first or second signal whereby increasing or decreasing the speed of said motor means upon receipt of said speed signal.

In combination with a machine including a tool for performing operations on a workpiece, a drive motor for actuating said tool, means for producing a first electrical output signal representative of the speed of said drive motor and an apparatus for positioning said workpiece relative said tool comprising:

• means for advancing said workpiece past said tool;
• at least one auxiliary motor adapted to drive said means for advancing at various speeds;
• means for producing a second electrical output signal representative of the speed of said auxiliary motor;
• bracket means adapted to mount said advancing means for movement between two positions, in one of which said advancing means is operative to move said workpiece past said tool and in the other of which said advancing means is rendered ineffective to transmit motive power to said workpiece;
• and
• means adapted to vary the speed of said auxiliary motor in a predetermined manner so as to initially effect displacement of said workpiece in a predetermined manner relative said tool and then drive said auxiliary motor and said drive motor at a preselected ratio whereby the workpiece is moved past said tool according to the speed of the drive motor.

In combination with a sewing machine having a frame, a needle for performing operations on a workpiece, a drive motor for actuating said needle, means for producing a first electrical output signal representative of the speed of said dirve motor, and an apparatus for positioning said workpiece relative said needle comprising:

• means for advancing said workpiece past said needle;
• at least one auxiliary motor adapted to drive said means for advancing at various speeds;
• means for producing a second electrical output signal representative of the speed of said auxiliary motor;
• and
• means adapted to vary the speed of said auxiliary motor in a predetermined manner so as to initially effect displacement of said workpiece in a predetermined manner relative said needle and then drive said auxiliary motor and said drive motor at a preselected ratio different from the above speed whereby the workpiece is moved past said needle according to the speed of the drive motor.