Sewing machine

Abstract

A sewing machine includes a needle, a needle bar which supports the needle, an upper feeding foot operable to feed the workpiece interlockingly with an up and down movement of the needle bar, a presser foot operable to press the workpiece, a holding bar which supports the presser foot, an actuator including an operating member operable to be changed to a first state, a second state or a no-load state, and a connecting portion which couples the operating member and the holding bar. The holding bar is constantly biased downward by a biasing force. The actuator moves the presser foot up against the first biasing force when the operating member is in the first state, and moves the presser foot down when the operating member is in the second state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a vicinity of a needle bar of a sewing machine according to a first embodiment.

FIG. 2 is a side view showing the vicinity of the needle bar shown in FIG. 1.

FIG. 3 is a perspective view showing a vicinity of an air cylinder of the sewing machine shown in FIG. 1.

FIG. 4 is an explanatory view showing a bobbin, a thread take-up, a shuttle of the sewing machine shown in FIG. 1.

FIG. 5 is a pneumatic circuit diagram of the air cylinder shown in FIG. 3.

FIG. 6 is a block diagram showing a control constitution of the sewing machine shown in FIG. 1.

FIG. 7 is a perspective view showing a state in which a piston rod of the air cylinder shown in FIG. 3 is rearwardly moved.

FIG. 8 is a timing chart showing an example of an operation of the sewing machine shown in FIG. 1.

FIG. 9 is a perspective view showing a modified example of the sewing machine shown in FIG. 1.

FIG. 10 is a perspective view showing another modified example of the sewing machine shown in FIG. 1.

FIG. 11 is a perspective view showing a vicinity of an air cylinder of a sewing machine according to a second embodiment.

FIG. 12 is a pneumatic circuit diagram of the air cylinder shown in FIG. 11.

FIG. 13 is a pneumatic circuit diagram showing a forwardly moved state of the air cylinder shown in FIG. 12.

FIG. 14 is a pneumatic circuit diagram showing a neutral state of the air cylinder shown in FIG. 12.

FIG. 15 is a pneumatic circuit diagram showing a rearwardly moved state of the air cylinder shown in FIG. 12.

FIG. 16 is a perspective view showing a restricted state of a biasing member shown in FIG. 11.

FIG. 17 is a perspective view showing a moved up state of a presser foot shown in FIG. 11.

FIG. 18 is a timing chart of an operation of the sewing machine shown in FIG. 11.

FIG. 19 is a perspective view showing a modified example of the sewing machine shown in FIG. 11.

FIG. 20 is a pneumatic circuit diagram of the modified example of the sewing machine shown in FIG. 12.

FIG. 21A through FIG. 21D are explanatory views showing operations of an upper feeding foot, a presser foot and feeding teeth when a workpiece is fed in a sewing machine of a related art.

FIG. 22 is a perspective view showing a vicinity of a needle bar of the sewing machine of the related art shown in FIG. 21.

FIG. 23 is a perspective view showing a state in which a piston rod of the air cylinder is rearwardly moved in the sewing machine shown in FIG. 22.

Claims

1. A sewing machine comprising: a needle operable to penetrate a workpiece on a throat plate and operable to form a stitch with a shuttle;a needle bar which supports the needle at a lower end thereof and operable to move up and down;an upper feeding foot operable to contact with the workpiece from above and operable to feed the workpiece interlockingly with an up and down movement of the needle bar;a presser foot operable to press the workpiece;a holding bar which supports the presser foot at a lower end portion thereof, the holding bar being constantly biased downward by a first biasing force;an actuator including an operating member operable to be changed to a first state, a second state or a no-load state; anda connecting portion which connects the operating member and the holding bar,wherein the actuator moves the presser foot up against the first biasing force when the operating member is in the first state, and moves the presser foot down when the operating member is in the second state.

2. The sewing machine according to claim 1, further comprising: a control portion operable to control the operating member,wherein, when a sewing starts, the control member brings the operating member into the no-load state, andwhen the needle penetrates through the workpiece and forms a first stitch, the control member brings the operating member into the first state for a predetermined time period, and thereafter, brings the operating member into the second state.

3. A sewing machine comprising: a needle operable to penetrate a workpiece on a throat plate and operable to form a stitch with a shuttle;a needle bar which supports the needle at a lower end thereof and operable to move up and down;an upper feeding foot operable to contact with the workpiece from above and operable to feed the workpiece interlockingly with an up and down movement of the needle bar;a presser foot operable to press the workpiece;a holding bar which supports the presser foot at a lower end portion thereof, the holding bar being constantly biased downward by a first biasing force;an actuator including an operating member operable to be changed to a first state, a second state or a no-load state;a connecting portion operable to connect the operating member and the holding bar, and a gap is provided in a connecting path of the connecting portion; andan biasing member which applies a second biasing force in a direction of reducing the gap,wherein the second biasing force is smaller than the first biasing force,the actuator moves the presser foot up against the first biasing force when the operating member is in the first state, andthe presser foot is moved down by the first biasing force when the operating member is in the second state.

4. The sewing machine according to claim 3, further comprising: a control portion operable to control the operating member,wherein, when a sewing starts, the control member brings the operating member into the no-load state, andwhen the needle penetrates through the workpiece and forms a first stitch, the control member brings the operating member into the first state for a predetermined time period, and thereafter, brings the operating member into the second state.

5. The sewing machine according to claim 3, wherein the biasing member includes an elastic member.