JPS6112954Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a thread cutting device for a blind sewing machine, and particularly to a thread cutting device for a blind sewing machine that is used when cutting sewing machine thread after one step of a blind sewing operation.

Technical background of the invention Generally, when sewing the hem of pants, a blind stitch is performed, and a blind sewing machine is used at that time. FIG. 1 is a schematic diagram of a blind sewing machine, and a general explanation will be given using this diagram.

In other words, like a normal lockstitch sewing machine, pulley 1
is provided on the upper shaft 2, the upper shaft 2 has a needle swing eccentric 3 and a looper crank 4, and a looper 6 is provided via a looper mounting shaft 5.

On the other hand, a needle (not shown) is provided at the tip of the needle swing rod 7, needle swing shaft arm 8, needle swing shaft 9, and needle swing arm 10. 11 is a presser foot rest. Further, a push-up rod 13 is provided to the upper shaft 2 via a pen sensor set screw 12, and a push-up plate detent 14 is connected via a series of links. This push-up plate rotation stopper 14 is provided with a push-up shaft 15, and a push-up plate 16 is attached to the tip of the push-up shaft 15. Therefore, the swinging motion of the push-up rod 13 is transmitted to the push-up shaft 15, and further converted into a horizontal swinging motion of the push-up plate 16 via the push-up shaft 15.

In this type of blind sewing machine, it is necessary to cut the thread each time one process is completed, and in consideration of this situation, a thread cutting device shown in FIG. 2 has already been proposed. That is, 17 is a thread cutting device, in which an extrusion shaft 18 is inserted into a body portion 19 by a spring (not shown), a knife 21 is fixed to a clamping portion 20 that is integrated with the shaft 18, and these are attached to a bracket 22. is supported by In addition, 23 is the head, and by pressing this part the knife 21
protrudes against the spring, hooks the thread to the hook-shaped part at the tip of the knife, and uses the spring's repulsive force to cut the thread. This thread cutting device is installed in the third
As shown in the figure.

FIG. 3 is a schematic view seen in the X-X′ direction of FIG. 1, and shows the presser foot supports 1 on both sides of the needle swing arm
Bracket 22 on one 11' of 1', 11''
It is tilted and fixed by. Then, cut the thread as shown in FIG.

That is, FIG. 4a shows the sewing machine needle 24 attached to the tip of the needle swing arm 10 when the operation of the blind sewing machine is stopped.
When the looper 6 and the looper 6 are in the relative positions shown in the figure, the knife 21 of the thread cutting device 17 is inserted into the loop of the thread 25 supported by the looper 6, and the thread is cut as shown in FIG. 4b. The thread is cut by the repulsive force of the spring.

Problems with the Background Art In the case of the conventional thread cutting device having the above configuration, the knife 21 is made to protrude by pushing the head 23 by hand, and the thread is cut using the repulsive force after the thread is tied. A force is applied when the thread is pulled. In this case, if the fabric being blind stitched is thin, the entire fabric will be tightened, and since the tightening force of the thread is used, it is difficult to cut.

Purpose of the invention The present invention was made to solve the above-mentioned problems, and its purpose is to provide a thread cutting device for a blind sewing machine that easily cuts threads without applying force to the fabric.

Summary of the invention In this invention, a scissor section is provided at the tip of the shaft.
The blades of the scissors close in response to the extrusion of the shaft, allowing the thread to be cut without applying any force to the thread.

Embodiments of the invention An embodiment will be described below with reference to the drawings. FIG. 5 is an overall perspective view of an embodiment of a thread cutting device for a blind sewing machine according to the present invention.

In FIG. 5, reference numeral 26 denotes a thread cutting device, which is composed of, for example, a square body portion 27, a shaft 28 passing through the inside thereof, a head portion 29, and a scissor portion 30 . A spring (not shown) is provided inside the body portion 27, and is normally subjected to a force in the direction of arrow A in the drawing due to the elasticity of the spring. The scissors part 30 is composed of a rotating blade 31 and a fixed blade 32, of which the rotating blade 31 is connected to a pin 33 provided on the side wall of the body part 27.
and a guide groove 34 having a curvature.

On the other hand, the fixed blade 32 is fixed to a fixed part 28' provided at the end of the shaft with a screw 36, and the rotating blade 31 is rotated to the end of the shaft with a screw 35 through a hole (not shown) in the fixed blade 32. Supported for free movement. Here, the screw 35 only passes through a hole (not shown) in the fixed blade 32 and does not fix it in any way, and as described above, the fixed blade 32 is attached to the fixed part 28' provided at the end of the shaft only by the screw 36. Fixed.

In FIG. 6, a and b are diagrams for explaining the operation,
Figures 6a and b are side views and plan views before operation;
Figures c and d are a side view and a plan view after operation. As shown in FIG. 6a, the upper position is normally maintained by the spring in the body 27, and therefore the rotary blade 31 is moved in the guide groove 34 and by the screw 35. The blade is in an open state (Fig. 6b). Next, when the head 29 is pushed down against a spring (not shown), the shaft 28 protrudes downward from the body 27, and the fixed blade 32 and the rotating blade 31 also start moving downward accordingly (sixth Figure c). At this time, the pin 33 of the rotating blade 31 moves along the inside of the guide groove 34 while drawing a curvature, and as a result, the rotating blade 31 moves with the screw 35.
Close using the fulcrum as the fulcrum (Fig. 6 d). Therefore, the scissors 30 are sequentially closed as the shaft 28 is pushed down, and the thread can be cut when the shaft 28 is pushed down the most.

FIG. 7 is a diagram showing how the thread cutting device is installed. A cut groove 37 is bored in the main body side of the needle swinging arm 10, and the body 27 is inserted into the cut groove 37 and fixed with a screw 38.

In the above embodiment, it was explained that the head of the thread cutting device was pressed down by hand, but the present invention is not limited to this, and as shown in FIG. Also good.

That is, an electric contact 40 may be provided that becomes "on" when the footboard of the sewing machine is pressed backward, and this may energize the solenoid 39 to push down the head of the thread cutting device. Of course, the specific configuration can be made arbitrarily.

Effects of the Invention As explained above, according to the present invention, the scissors are configured to close in response to the pushdown of the shaft, so it is possible to easily cut the thread without applying straining force, and therefore, it is possible to cut thin fabrics easily. To provide an extremely efficient thread cutting device for a blind sewing machine, which allows sewing work to be performed without damaging the sewing machine.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the main parts and operating principles of a blindstitch sewing machine, Fig. 2 is an overall perspective view of a conventional thread trimming device, Fig. 3 is a diagram showing the installation state of the conventional thread trimming device, and Fig. 4 The figure is a diagram explaining the conventional thread trimming state.
The figure is an overall perspective view of the thread cutting device of the blind sewing machine according to the present invention, and FIG. 6 is a diagram illustrating the operating state.
Figures 6a and b show the state before operation, and Figures 6c and d
7 is a diagram showing the state after operation, FIG. 7 is a diagram showing the installed state, and FIG. 8 is a diagram for electrically driving the thread cutting device. 1... Pulley, 2... Upper shaft, 3... Needle swinging eccentric, 4... Looper crank, 5... Looper mounting shaft, 6... Looper, 7... Needle swinging rod,
8... Needle swing shaft arm, 9... Needle swing shaft, 10... Needle swing arm, 11 ... Presser foot holder, 11', 11''... Presser foot rest support, 12... Pen sensor set screw, 1
3... Thrust rod, 14... Thrust plate rotation stopper, 15... Thrust shaft, 16... Thrust plate, 1
7, 26 ... Thread cutting device, 18, 28... Shaft, 19, 27... Body part, 20... Clamping part, 21
...Knife, 22...Bracket, 23, 29...
...Head, 24...Sewing machine needle, 25...Thread, 28'
... Fixed part, 30 ... Scissors part, 31 ... Rotating blade, 32 ... Fixed blade, 33 ... Pin, 34 ... Guide groove, 35, 36, 38 ... Screw, 37 ... Cut groove, 39... Solenoid, 40... Electric contact.

Claims (1)

[Scope of utility model registration request] In a thread cutting device for a blind sewing machine, in which a shaft inserted into a body moves against a spring, and a thread cutting means is activated in accordance with the movement of the shaft, the thread cutting means is composed of a rotating blade and a fixed blade. The rotary blade is provided with a guide groove having a curvature and is slidably locked to the side wall of the body by a pin, and the fixed blade is fixed to the end of the shaft. A thread cutting device for a blind sewing machine, characterized in that a rotary blade is supported by a screw at the end of the shaft.