JPH0367717B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an automatic thread cutting device that can be used in a sewing machine to cut thread ends as short as possible.

[Conventional technology]

In recent years, needle thread,
It is equipped with a device that cuts the bobbin thread at the same time to improve the efficiency of sewing or embroidery.

For example, there are those disclosed in JP-A-51-88347, JP-A-52-34846, and JP-U-58-130680.

[Problem to be solved by the invention]

However, the known automatic thread cutting device has a complicated structure and operation, and cuts the thread by driving a movable blade against a fixed blade so as to press the fed-out thread between the fixed and movable blades. For this reason, one of the opposing blades that moves like scissors is fixed and only the other is movable, which has the advantage of determining the thread cutting position, but depending on the type of thread, the thread may slip between the two blades and cut securely. There are some things that cannot be done, and since the thread is cut at a position away from the thread insertion hole in the throat plate, the thread end is at most about 7 mm short. Therefore, even if automatic thread cutting is performed, a work step is required to cut off the excess thread end with scissors after embroidery.

The present invention cuts by swinging two opposing cutters toward and away from each other and with different swing amounts, and by cutting directly below or near the throat plate, the length of the cut thread end is 2 to 3 mm. The object of the present invention is to make it as close as possible and to eliminate the work of aligning thread ends with scissors after embroidery is completed.

[Means to solve the problem]

The present invention has been made in order to achieve the above-mentioned object.A hook that always swings ahead of one movable blade is fixed coaxially with one movable blade, and a pin provided on this movable blade is connected to the other movable blade. It is inserted into a long hole formed in the movable blade, and both movable blades are uncoupled within the permissible angle range through this long hole and pin, and the time difference between the pins moving in the long hole is set. The gist is that the two movable blades are connected in a swinging manner, and that two opposing movable blades are swinged toward and away from each other by rotation of the shaft to cut the thread. In addition, a hook is rotatably fixed integrally or coaxially so that it always swings ahead of one movable blade, and the other movable blade facing this movable blade is pivoted coaxially with the shaft. are vertically disposed on the lower surface of the throat plate, and the movable blades are synchronized and oscillated in the approaching and separating directions with different amounts of oscillation, thereby cutting the thread at a position below the needle hole of the throat plate.

[Effect]

A hook that always swings ahead of one movable blade is fixed coaxially with one movable blade, and this movable blade and the other movable blade are connected through a pin and an elongated hole with a time difference within an allowable angle range. The two movable blades are movably connected in an unconnected state, and the two opposing movable blades are swung toward and away from each other by rotation of the shaft to cut the thread, thereby ensuring reliable thread cutting. The yarn end length can be made as short as possible.

〔Example〕

The present invention will be explained below based on a first embodiment shown in FIGS. 1 to 4.

In the figure, reference numeral 1 denotes a lower body block of the sewing machine, inside which a hook shaft 2 is rotatably disposed as shown in the figure, and this shaft is rotatably driven by a drive source. In the case of a single-turn hook, the needle rotates once per one stroke of the hook, and in the case of a double-turn hook, it rotates twice in the same manner.The outer hook 3 is fixed to the tip of the hook shaft 2, and rotates together with the hook shaft 2. The inner hook 4 is fitted into the outer hook 3 so as to be movable. Although not shown in the drawings, a bobbin on which a bobbin thread is wound is provided inside the inner hook 4 so that it can be attached and detached via a bobbin case. The inner pot is always supported so that it remains stationary even when the pot rotates together with the hook shaft.

A needle thread hooking and feeding device is provided which hooks the needle thread from an outer hook and lets it out to a required length, and when cutting the needle thread, the needle thread is drawn out to the required length required for cutting. Since this needle thread hooking and letting-out method employs a conventional method, its explanation will be omitted.

A throat plate 6 is provided above the outer hook, that is, on the top surface of the lower main body block, in the same manner as in conventional sewing machines. Then, on the lower surface of this needle plate 6, as shown in FIGS. 1 and 2,
A device is provided to feed and cut the sewing thread. This mechanism is shown in a plan view with the throat plate removed in FIGS.
A lever 7 that hooks the bobbin thread on either the right or left side and lets it out to a required length, and two movable blades 8 and 9 that cut the fed out thread at a predetermined position.
Consists of.

Next, this automatic thread cutting device will be explained based on FIGS. 1 to 4.

A rotary solenoid 11 for swinging the hook is provided on the solenoid mounting plate 10 provided on the lower surface of the lower main body block 1, and a lever 12 is attached to the shaft of the solenoid.
is fixed, a hook 12F with a forked tip is bored in this lever 12, and the hook 12F is swung by driving the solenoid 11, and the tip of this hook is brought into contact with the front surface of the inner pot, and the hook 12F is fixed. A portion of the thread that is let out by the rotation is hooked onto this hook, and the thread is let out so that it has the length necessary for cutting.

The two movable blades 8 and 9 are slidably stacked on top of each other in vertical positions, and the base end side of one of the lower movable blades 8 is fixed to the upper end of a shaft 13 supported by a bearing 1B of the lower main body block 1. A drive rod 15 is locked to a lever 14 protruding from the lower end of this shaft 13, and by moving the rod 15 forward and backward, the lever 14 and the shaft 13 are moved.
The other upper movable blade 9 is disposed at the upper end of this shaft 13, and the base end thereof is connected to the lower body block 1 by a shaft 16. The two movable blades 8 and 9, which overlap each other vertically, are arranged in a V-shape so that the shaft 13 is the intersection point of the two movable blades, and are movable toward and away from each other. Then, the upper and lower movable blades 8 and 9 that face each other in a V-shape are slid toward and away from each other. The blades are cut so that their blade portions intersect with each other at a position almost directly below the insertion hole 6a. The base end of the upper movable blade 9 is slidably supported by the shaft 16 toward the lower block as described above. Therefore, even though the upper movable blade 9 and the lower movable blade 8 have different pivot axes, they act like scissors.

Further, a hook 7 is provided at the upper end of the shaft 13 and adjacent to the lower position of the lower movable blade 8, and is fixed to the lower movable blade 8 so as to form a V-shape at a fixed angle, that is, a predetermined angle. The thread insertion hole 6a of the throat plate is positioned on the swing locus of the hook 7, and a thread hooking notch 7a is formed to ensure that the thread is hooked. The upper movable blade 9 is not connected to the shaft 13, but the lower movable blade 8 and the upper movable blade 9 are inserted into the oblong hole 9H drilled in the upper movable blade 9. Pin 1 protruding from
5P and the upper movable blade 9 through the hole 9H.

Furthermore, this oval hole 9H allows the shaft 13 to rotate, and even if one of the lower movable blades 8 fixed thereto swings, the other upper movable blade 9 remains stationary, and the shaft 1
Even if the thread passed through the throat plate is hooked on the hook 7 fixed to the hook 3 and fed out toward the stopped upper movable blade, the thread will not come into contact with the upper movable blade 9, and the thread will not touch the upper movable blade 9. When the thread is let out for the required length by the rotation of the hook 13, the upper movable blade 9 begins to swing due to the action of the hole 9H and the pin 15P, and swings in the direction toward the lower movable blade 8. There is. The thread is then cut at the position where the blade portions of both the upper and lower movable blades 8 and 9 intersect.

Next, the operation of the present invention will be explained.

When cutting the thread, when the rod 15 is slid, the shaft 1 supported by the rod via the lever 14
3 rotates. First, the lower movable blade 8 swings in a direction toward the yarn. At this time, the hook 7 fixed to the shaft 13 also swings at the same time. Since this hook 7 has a V-shape at a predetermined angle with respect to the lower movable blade 8, the hook 7 always comes first. The thread is hooked onto the hook 7 and let out to the required length for cutting. When the lower movable blade 8 swings to a predetermined angle, the pin 15P comes into contact with the inner peripheral surface of the hole 9H, and further swinging of the lower movable blade 8 causes the pin 15P to come into contact with the inner peripheral surface of the hole 9H.
P will push the upper movable blade 9 that faces this through the hole circumferential surface. At this time, the pin 15P moves in the same direction as the lower movable blade 8 around the shaft 13, but the other upper movable blade 9 moves toward the shaft 16 at a position away from the shaft 13.
The upper movable blade 9 is pivotally connected to the lower movable blade 8.
It will swing in opposite directions. As a result, the opposing upper and lower movable blades 8 and 9 swing in the direction toward each other, and cut the thread that is hooked by the hook and let out by sandwiching the thread between them. At this time, the lower movable blade 8 always swings in advance of the upper movable blade 9, the swing angle is large, and the intersection of both blades is placed directly below the needle hole in the throat plate or close to it. The yarn can be cut reliably, and the length of the cut yarn end can be made as short as possible, which was not possible with conventional cutting positions.

After cutting the thread, the vertically movable blades 8, 9 and the hook 7 can be returned to their original positions by rotating the shaft 13 in the opposite direction to that during cutting.

Note that it is also possible to omit the hole 9H and pin 15P and provide the movable blade 9 with a driving device so as to drive it so as to meet the above-mentioned conditions. This second embodiment is shown in FIGS. 5 to 7.

In this second embodiment, the structure is almost the same except for the method of moving the upper movable blade 9 and the lower movable blade 8, and therefore, explanation of the same components as in the first embodiment will be omitted.

A long hole 8H is bored at the tip of the lower movable blade 8, and a pin 17 is fitted into this long hole 8H.
7 is established on the crank 18, and when the crankshaft 19, which is locked to the rod 22, rotates the crankshaft 19 by the sliding operation of the rod 22, the crank 18 turns around the crankshaft 19, and this As a result, the pin 17 also rotates around the crankshaft 19, causing the lower movable blade 8 to swing around the shaft 13 through the elongated hole 8H into which the pin 17 is fitted. The lower movable blade 8 is provided with a hook 7 on the shaft 13 so as to be in front of the lower movable blade 8, as in the first embodiment.

The upper movable blade 9 is pivoted to the same shaft 13 as the lower movable blade 8, respectively, and a pin 20 is fitted into an elongated hole 9H provided at the base end side of the upper and lower movable blades. This pin 20 projects from a block 21 fixed to the rod 15. And this action consists of two rods 2
1 and 22, their operating times, ie timings, are slightly shifted so that they operate in the same way as in the first embodiment.
Furthermore, the amount of swing of the lower movable blade 8 is set in advance to be smaller than that of the upper movable blade.

〔Effect of the invention〕

According to the present invention, a hook that always swings ahead of one movable blade is fixed coaxially with one movable blade, and this movable blade and the other movable blade are connected through a pin and an elongated hole within an allowable angle range. The two movable blades facing each other are connected in an unconnected state by the rotation of the shaft, and the two movable blades are swung toward and away from each other, with a time difference, and with different amounts of oscillation to cut the thread. Because of this, the length of the cut yarn end can be made as short as possible and cutting can be carried out reliably, and the work of aligning the yarn end after the work can be omitted, which has the advantage of improving work efficiency.

[Brief explanation of drawings]

Figures 1 to 4 show the first embodiment, where Figure 1 is a plan view without the throat plate, Figure 2 is a front view, Figure 3 is a side view, and Figure 4 is an explanatory diagram of the operation. . 5 to 7 show a second embodiment. FIG. 5 is an explanatory diagram as seen from the back side of the throat plate, and FIGS. 6 and 7 are explanatory diagrams of the driving parts of the upper movable blade and the lower movable blade. 4 is the inner hook, 5 is the hook stop, 6 is the throat plate, 7 is the lever, 8 is the lower movable blade, 9 is the upper movable blade, 9H is the hole, 1
3 is the shaft, 15 is the rod, and 22 and 23 are the rods.

Claims (1)

[Claims] 1. A hook that always swings ahead of one movable blade is fixed coaxially with one movable blade, and a pin provided on this movable blade is inserted into an elongated hole formed in the other movable blade. Through this elongated hole and the pin, both movable blades are in an uncoupled state within the allowable angle range, and the two movable blades are connected so that they swing with a time difference while the pin moves inside the elongated hole. An automatic thread cutting device for a sewing machine, wherein the thread is cut by swinging two opposing movable blades toward and away from each other by rotation of the shaft. 2. A shaft on which a hook is rotatably fixed integrally or coaxially so that it always swings ahead of one movable blade, and the other movable blade facing this movable blade is pivoted coaxially with said shaft. is installed vertically on the lower surface of the throat plate, and the movable blades are synchronously swung in the approaching and separating directions with different swing amounts and directions to cut the thread at the lower position of the needle hole in the throat plate. An automatic thread trimming device for a sewing machine, which is characterized by: