Granted Patent B2

US 8,925,473 · App. 12/680,736 · Granted Jan 6, 2015

Abstract

Claims (56)

1. A method for cutting at least an upper thread of a sewing machine, wherein a length of the thread consumed for a cut can be set within a predetermined interval, said sewing machine having a thread feeder for the upper thread, a thread cutter, a fabric clamping member, a processor for controlling said thread cutter, thread feeder, and fabric clamping member, and a memory, the sewing machine also having an adjustable height presser foot, the method comprising:

feeding by said thread feeder a predetermined length (x) of said upper thread to be consumed in a cut sequence,

pulling out the upper thread said predetermined length by displacing a displacement of said fabric clamping member from a first position to a second position,

instructing the processor to execute at least one program sequence stored in the memory, the at least one program sequence configured to operate said thread cutter to perform a cut of at least said upper thread.

2. The method according to claim 1 , further comprising:

setting said predetermined length (x) of thread to be consumed to be d<x≦L=2k, wherein d is the thread length consumed in a cut when said feeding and pulling is not performed and k is a maximum possible displacement of a needle within the fabric clamping member whereby said consumed thread can be set within the interval d to d+L, depending on the position of the needle when performing said cut.

3. The method according to claim 1 or 2 , wherein said at least one program sequence executed by the processor of the sewing machine includes an algorithm having the steps of:

providing the predetermined amount of thread (x) to be consumed in the cut sequence;

moving the fabric x/2 mm in a set direction; and

moving the fabric clamping member −x/2 mm to the position it had before the start of the cut sequence.

4. The method according to claim 3 , wherein the processor is instructed to execute a program sequence having an algorithm including the steps of:

S1: Set upper thread control system in tension mode;

C1: Upper thread control system in reached tension mode;

S2: Set the presser foot in DOWN pos;

S3: Set a main shaft of the sewing machine in SECTOR 0 ;

C2: Main shaft stopped in SECTOR 0 ;

S4: Set the fabric feeder in pos. 0 ;

C3: Presser foot in DOWN pos;

C4: Fabric feeder in pos. 0 ;

S5: Start a thread fetcher of the thread cutter, motion 1 ;

C5: Motion 1 performed;

S7: Set thread tension;

C7: Thread tension set;

S6: Set a main motor of the sewing machine in SECTOR 12 ;

C6: Main motor passed SECTOR 12 ;

S12: Set the presser foot in LIFT pos;

C11: Presser foot in LIFT pos;

S13: Set the upper thread control system in feeding mode;

C12: Feeding mode set;

S14: Provide the amount of extra thread (x) to be consumed in the cut sequence

C13: Delay (approx. 200 ms.)

S15: Move the embroidery frame x /2 mm in a set direction;

C14: Embroidery frame position set;

C15: Thread feed performed;

S8: Start thread fetcher of the thread cutter, motion 2 ;

C8: Motion 2 performed;

S16: Set the upper thread control system in tension mode;

C16: Tension mode set

S9: Set thread tension

C9: Thread tension set

S17: Set the presser foot in LOWERED pos

C17: Lowered pos. set

S10: Start thread fetcher, motion 3

C10: Motion 3 performed

S11: Calibrate the thread fetcher motor

C18: Calibration performed

S18: Set the presser foot in PIVOT pos;

C19: PIVOT pos. set;

S19: Move the embroidery frame −x/2 mm (to the pos. it had before the cut sequence started);

C20: Embroidery frame position set.

5. A computer program product coded with the steps for performing said method including the steps of the algorithms in any of claim 3 or 4 .

6. A sewing machine comprising:

a thread feeder for the upper thread,

a thread cutter,

a fabric clamping member,

a processor for controlling said thread cutter, said thread feeder and said fabric clamping member for performing the method of claim 1 .

Assignments (16)