JPS6047866B2 - Sewing machine cloth cutting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thread cutting device for a sewing machine, and more particularly to a thread cutting device that moves up and down in conjunction with an upper shaft via a clutch mechanism.

Conventionally, various thread cutting devices of this type have been provided, but they have had the disadvantage that the clutch mechanism has become complicated and large.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a thread cutting device for a sewing machine that has a simple structure and is equipped with a latch mechanism. Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings. In Figures 1 to 3 and Figure 11, 1
0 is an upper shaft rotating within an arm 12 of a sewing machine 11, and this upper shaft 10 is connected to the right end of a drive shaft 15 via an eccentric cam 13 and a first arm 14. The left end of the drive shaft 15 is connected to second arms 1 and 7 each having a pin 16 implanted in its tip.
is adapted to swing as the upper shaft 10 rotates.
Reference numeral 18 denotes a female shaft, which is adapted to vertically swing a first bush 20 and a second bush 21 fitted into the upper and lower parts of the jaw portion 19 of the arm 12.
An upper knife 23 attached to a knife stand 22 fixed to the lower end of the knife 8 cooperates with a lower knife (not shown) disposed on a bed 24 to cut the cloth.

A retainer 25 is fixed approximately at the center of the female shaft 18, and a spring 26 is tensioned between the retainer 25 and the second bush 21 to urge the female shaft 18 upward. . A clutch body 27 is rotatably provided on the female shaft 18, and is provided with a first protrusion 28 and a second protrusion 29 protruding in the radial direction at its upper and lower ends, respectively.

The clutch body 27 also includes a guide 31 on which a guide surface 30 is formed, a first groove 32 between the upper end of the guide 31 and the first projection 28, and a first groove 32 between the lower end of the guide 31 and the second A second groove 33 is formed between the protrusion 29 and the protrusion 29, respectively. A horizontal protrusion 34 extends from the retainer 25, and this horizontal protrusion 34 is fitted into the second groove 33. When the torsion spring 35 is stretched between the clutch body 27 and the retainer 25, the clutch body 25 is designed so that it does not move upward.

As shown in FIG. 4, rotation of the clutch body 27 in one direction by the torsion spring 35 is restricted by a stopper 37 fixed to the retainer 25 with a screw 36. Thus, the pin 16 and the clutch body 27 constitute a clutch 38, and when the pin 16 is engaged with the guide surface 30 of the clutch body 27 (FIG. 4), the clutch mechanism 38 does not act and the pin 16 clutch body 2
When the female shaft 18 is fitted into the first groove 32 of No. 7 (FIGS. 6 and 7), the clutch mechanism 38 is activated and the female shaft 18 moves up and down in conjunction with the upper shaft 10.

Reference numeral 39 denotes a face plate attached to the end face of the arm 12, which pivotally supports the lever 40.

However, Reba. The bush portion 40a is biased outward from the arm 12 by the 140-port return spring 41, and its tip portion 40b faces and can engage with the guide surface 30 of the clutch body 27. To describe the function of the above configuration, the clutch! When the mechanism 38 is not operating as shown in FIG. 4, even if the pin 16 swings as the upper shaft 10 rotates, the clutch body 27 only rotates alternately in one direction and the other direction. It is. Next, when the female shaft 18 is pressed downward, the clutch body Q27 descends against the spring 26 until the pin 16 engages with the first protrusion 28, as shown in FIG. When the pin 16 engages with the first protrusion 28, the clutch body 27 further rotates in one direction due to the action of the torsion spring 35 until it is stopped by the stopper 37. As shown in FIG. 7, it fits into the first groove 32 of the clutch body 27, and the clutch mechanism 38 operates. Therefore, if the sewing machine 11 is driven in this state, the pin 16 interlocked with the upper shaft 10 will swing, and the knife shaft 18 will move up and down, so the upper knife 23 fixed to the knife shaft 18 will cooperate with the lower knife. work to cut the cloth. Further, when the cloth has been cut, when the pressing part 40a of the lever 40 is pressed, the state changes from the state shown in FIGS. 6 and 7 to the state shown in FIGS. 8 and 9, as shown in FIG.
The tip 40b of the lever 40 engages with the guide surface 30, the clutch body 27 is rotated in the other direction, and the pin 16 is moved into the first protrusion 2.
8, and then separates from the first groove 32. However,
Since the female shaft 18 is always urged upward by the spring 26, the clutch body 27 rises while the guide surface 30 is in contact with the pin 16 (FIG. 10). If the pressing on the pressing part 40a is stopped, the lever 40 will not return to its original position due to the action of the return spring 41, and the clutch body 27 and female shaft 18 will also return to their original positions (
Figure 4). As described above, the present invention uses a spring to bias upwardly a female shaft having an upper knife fixed to its lower end, which cooperates with a lower knife disposed on a bed, and a clutch body provided with a guide surface and a groove. A pin provided on the shaft and swinging in conjunction with the upper shaft by rotating the clutch body in one direction by a torsion spring is brought into contact with the guide surface, and when the female shaft is pressed, the pin moves into the groove. to move the female shaft up and down, and press the lever against the guide surface to rotate the clutch body in the other direction against the torsion spring to remove the pin from the groove. Since the cloth cutting device of the sewing machine is constructed in this way, the construction of the clutch mechanism can be simplified and a great effect can be achieved.

[Brief explanation of the drawing]

Figure 1 is a top view including a partial cross section of the sewing machine arm, Figure 2 is a sectional view taken along line ■-■ in Figure 1, and Figure 3 is a cross-sectional view along line ■-■ in Figure 1.
The cross-sectional view taken along the line and FIGS. 4 to 10 are diagrams for explaining the operation of the clutch mechanism that constitutes the essential part of the present invention, and FIG. 7 is a cross-sectional view taken along the line ■-■ in FIG. 9 is a sectional view taken along the line 1--2 in FIG. 8, and FIG. 11 is a perspective view of the clutch mechanism. 10: Upper shaft, 16: Pin, 18: Female shaft, 23: Upper knife, 24: Bed, 25: Retainer, 26: Spring,
27: clutch body, 28: groove, 30: guide surface, 35 torsion spring, 37 stopper, 40: lever.

Claims (1)

[Claims] 1 A knife shaft 18 mounted on the sewing machine arm 12 so as to be movable up and down, a first protrusion 28, a first groove 32,
A guide 31 having a guide surface 30, a second groove 33, and a second protrusion 29 are formed, a clutch body 27 is rotatably mounted on the female shaft 18, and the clutch body 27 is fixed on the female shaft 18 and has a second groove 33 and a second projection 29. a retainer 25 provided with a horizontal protrusion 34 located below the clutch body 27 and always fitted into the second groove 33 of the clutch body 27; a retainer 25 located between the clutch body 27 and the retainer 25; a torsion spring 35 that always biases the clutch body 27 to rotate in one direction;
7, the torsion spring 35
A stopper 37 is fixed to the retainer 25 to prevent excessive rotation of the clutch body 27 in one direction due to the action of A pin 16 that swings due to the action, a spring 26 that constantly corrects the retainer 25 upward, and a spring 26 that faces the guide surface 30 of the clutch body 27 and that faces the guide surface 3 of the clutch body 27.
a lever 40 that rotates the clutch body 27 in the other direction against the torsion spring 35 when engaged with the lever 40;
An upper knife 23 that cuts the cloth in cooperation with a lower knife disposed in
, a cloth cutting device for a sewing machine.