JPH0221832B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a sewing thread cutting device for a sewing machine, and relates to a sewing thread cutting device for a sewing machine having multiple needles such as a single needle chain stitch sewing machine or a covered needle chain stitch sewing machine. Used for cutting empty threads on sewing machines, etc.

(Prior art) As a conventional device of this type, there is a device in which empty yarn is held between comb teeth and then cut with a scalpel (U.S. Patent No.
3025811) etc. are known.

(Problems to be Solved by the Invention) In recent years, sewing threads made of thermoplastic synthetic resin fibers have come into widespread use, and when cut with a scalpel, the cut portion frays, and when burned out with a hot wire, etc. There was an inconvenience that the thread burned and the end of the thread became carbonized and clumped together.

The present invention is designed to prevent such inconvenience from occurring when cutting the empty thread.

[Structure of the invention]

(Means for Solving the Problems) As a means for solving the above-mentioned problems, in the present invention, a thread cutting punch is provided behind the needle drop in the sewing machine feed direction, and is actuated by an external force and heated by external energization.

Then, a female member was fixed at a position below the bed surface corresponding to the punch, and a punch holder that was movable up and down with a spring and had a thread holding surface was integrally combined with the knife.

The thread holding surface of the punch holder is configured to be located slightly above the blade tip of the knife under normal conditions.

(Operation) After one sewing item is sewn, when the empty thread portion passes through the thread holding portion of the punch holder, the sewing machine is stopped and the punch is pushed down by external force. (At this time, the punch is heated by an attached heater that is supplied with electricity from the outside.) Therefore, the lower surface of the punch presses the empty yarn against the yarn holding surface.

Then, as the punch descends further, the punch holder is pushed down against the spring, and the lower surface of the punch comes into contact with the blade of the fixed scalpel to cut the thread.

Both cut ends of the cut thread are fused together by the heat of the punch.

(Example) In FIGS. 1 and 2, 1 is an arm of a chain stitch sewing machine, 2 is a bed, 3 is a needle bar, and 4 is a presser foot.

Reference numeral 5 denotes a bracket, which is fixed to the rear attachment surface of the arm 1 with screws 6, to which an air cylinder 7 is attached, and to the cylinder shaft 8 of which an operating member 9 is attached. 10 is a guide member, 11 is a punch, and the two are connected with a screw 13 with a mica-protected heater 12 interposed between them.

Thus, the guide member 10 has the guide pin 1
4 and 14' are fitted into the guide portions 9' and 9'' of the actuating member 9 via springs 15 and 15' and held by locking nuts 16 and 16'. Terminal board 1
Power is supplied from an external line 20 connected to a terminal 19 of the terminal 8.

Reference numeral 21 denotes a female attachment member, which is attached to the bed 2 with screws 21' and is provided with retaining plates 22, 22'.

23 is a punch holder, which is an angle material with thread holding surfaces 23' and 23'', and has guide pins 2 at both ends.
5 and 25' are fixed with screws 27 and 27'.

The guide pins 25, 25' are held by the retaining plates 22, 22' by screws 28, 28' through guide springs 26, 267 which are thinner than the springs 15, 15'.

Reference numeral 24 denotes a knife fixed to the knife attachment member 21, and the cutting edge of the knife 24 in the normal state is aligned with the punch 23.
The entire assembly is adjusted so that it is located approximately 1 to 2 mm below the thread holding surfaces 23, 23'.

〔Effect of the invention〕

In order to solve the above technical problem, a heater (heat wire) and a thread cutting knife were installed in parallel, and the thread was pressed from the top (1974-47496), and a punch heated by the heater was inserted into the lower knife. It is also possible to cut the thread by applying pressure to the thread, but in both of these methods, the heat bonding and cutting are done almost at the same time, so the thread may be cut before the fusion progresses. In addition, there was a risk that the thread would be burned out by the heat before being cut with a scalpel. In the present invention, the punch holder (empty thread holder) is located slightly above the blade surface of the scalpel, so the thread is pressed by the heated punch and the thread fusing operation is performed, and then the knife disconnected by. In addition, since the punch presses both sides of the knife, the end of the thread at the end of sewing and the end of the thread at the beginning of sewing are always fused to prevent fraying, resulting in a reliable and beautiful cut. It can also be cut. Furthermore, if this device has multiple needles such as a multi-needle quilt sewing machine, if the punch and female part are extended as they are and the length is made to accommodate the multiple needles, it will be possible to use the empty thread of each needle. It is extremely efficient, as each thread can be fused and cut at the same time with one punch, making it ideal for automatic sewing, etc.

[Brief explanation of drawings]

FIG. 1 is a side view of a sewing machine equipped with a thread cutting device of the present invention, viewed from the face plate side, and FIG. 2 is an exploded view of the structure of the device shown in the first figure. 7... Air cylinder, 9... Operating member, 10
... Guide member, 11 ... Punch, 12 ... Heater, 21 ... Female mounting member, 23 ... Punch holder, 24 ... Female.

Claims (1)

[Claims] 1. A thread cutting punch that is activated by an external force and heated by external electricity is provided behind the needle drop in the sewing machine feed direction, and a female member is fixed at a position corresponding to the punch below the bed surface, A hollow thread cutting device for a chainstitch sewing machine, in which a punch holder having a vertically movable spring and a thread holding surface is integrally combined with the scalpel, and the thread holding surface is normally positioned slightly above the blade edge of the scalpel. .