JP2766047B2 - Sewing machine thread cutting device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting device for cutting a thread at the time of conversion of a sewing thread or at the end of sewing, for example, in an industrial embroidery sewing machine.

[Conventional technology]

FIG. 6 is a plan view showing a conventional yarn cutting device.
As is apparent from this drawing, the fixed knife 144 has a cutting blade formed above the shuttle 16 and formed toward the front side of the shuttle 16.
146. On the other hand, the moving knife 156 is reciprocated around the axis of the knife drive shaft 160 as a fulcrum in a range between a standby position X 'shown by a solid line in FIG. 6 and a thread dividing position Y' shown by a virtual line. It is possible. Further, the moving knife 156 has a cutting blade 158 using the inner peripheral edge of the through hole 157 opened at its free end.

FIGS. 7 and 8 are schematic perspective views showing the outlines of a thread splitting start state and a thread cutting start state by the conventional thread cutting device, respectively. First, as apparent from FIG. 7, the needle 16 is rotated by about 180 ° after the needle thread has been caught by the blade point of the shuttle 16 so that a part of the shuttle 16 that has rotated upward in the drawing has a needle-side needle thread. T1 and the cloth side upper thread T2 are separated. At this time, the moving knife 156 starts to rotate from the standby position X 'to the thread dividing position Y', and the needle side upper thread T1 is hooked by the thread dividing locking portion 168 of the moving knife 156, and the thread dividing position is changed. Carried to Y '
A so-called thread dividing process is performed.

Subsequently, as shown in FIG.
When the thread 156 starts rotating from the thread dividing position Y 'toward the standby position X', the cloth side upper thread T2 and the lower thread T3 are hooked by the thread trimmer 1666 of the moving knife 156, and the standby position X Carried to the end. In the process of rotating the moving knife 156 at this time, the respective cuttings 146 and 146 of the fixed knife 144 and the moving knife 156,
158 cuts the cloth side upper thread T2 and lower thread T3.

In addition, the thread end of the lower thread T3 pulled out from the bobbin in the shuttle 16 after cutting is fixed to the lower surface of the moving knife 156 at the standby position X 'in FIG. It is pinched.

[Problems to be solved by the invention]

In the conventional thread cutting device, during the thread dividing process shown in FIG. 7, the needle-side upper thread T1 is carried toward the front side of the shuttle 16 by the thread dividing locking portion 168 of the moving knife 156. Therefore, the needle-side upper thread T1 and the cloth-side upper thread T2 located on the front side of the shuttle 16 are more strongly crossed with each other, and thread entanglement is likely to occur during thread splitting.

In the thread cutting process shown in FIG. 8, the cloth side upper thread T2 and lower thread T3
Are transported to the back side of the shuttle 16 so that these yarns T2 and T3
The needle-side upper thread T1 located closer to the back of the shuttle 16 may be brought in together.

The main cause is the yarn entanglement at the time of the yarn splitting and the carry-in of the needle-side upper thread T1 at the time of the cutting process.
T1 may also be cut along with the cloth side upper thread T2 and lower thread T3. That is, in this case, since the loop-shaped thread is cut at two places, the size of the needle-side upper thread T1 is insufficient, leading to a sewing error and thread waste.

Even if the thread is cut properly, the thread end of the bobbin thread T3 pulled out from the bobbin in the shuttle 16 after cutting is directed to the rear side of the shuttle 16 by the thread presser 150 and the moving knife 156. If the holding of the lower thread T3 is not appropriate, this also causes a sewing error.

The technical problem of the present invention is to avoid a situation in which the needle-side upper thread is brought together with the thread at the time of thread splitting or thread cutting, and a sewing error or thread waste caused by the needle-side upper thread being erroneously cut. The thread end of the lower thread pulled out of the bobbin in the shuttle after thread cutting is guided to the front side of the shuttle, so that even if the thread end is not properly held, sewing can be started. The present invention provides a sewing machine thread cutting device capable of performing the cutting properly.

[Means for solving the problem]

In order to solve the above problems, a thread cutting device for a sewing machine according to the present invention is configured as follows.

That is, a hook is arranged below the needle plate of the hook base, and a fixed knife fixed to the hook base side between the needle plate and the hook,
A moving knife provided rotatably in the range of the thread splitting position and the standby position, and a fixed knife and a moving knife when rotated from the thread splitting position to the standby position, a predetermined lower portion of the needle plate is provided. Is cut. The thread to be cut is an upper thread (hereinafter referred to as a cloth-side upper thread) and a lower thread connected to the sewing end portion of the cloth to be sewn.

In the above configuration, the fixed knife has a cutting blade formed on the front side of the shuttle and toward the rear side. The cutting blade formed on the free end of the moving knife is located on the front side of the shuttle when the moving knife is rotated to the standby position.

At the edge of the moving knife, a thread trimmer engaging portion for hooking the cloth side upper thread and lower thread to be cut and moving the moving knife to the front side of the shuttle when the moving knife rotates toward the standby position. Are formed. Similarly, an upper thread connected to a sewing needle when the moving knife rotates toward the thread splitting position (hereinafter referred to as a needle-side upper thread) is provided on an edge of the moving knife that is opposite to the thread cutting locking portion. Is hooked and is moved to the rear side of the shuttle to form a thread dividing locking portion.

[Action]

According to the configuration, the moving knife is rotated from the standby position to the thread dividing position, that is, from the front side to the rear side of the shuttle, so that the needle-side upper thread is hooked on the thread dividing locking portion. It is carried to the back side of the kettle. The needle side upper thread at this time is
It is pulled in a direction to uncross (separate) with the cloth side upper thread located on the front side of the shuttle. Therefore, the yarn dividing process can be properly performed without causing the needle-side upper yarn, the cloth-side upper yarn, and the lower yarn to become entangled with each other.

In addition, when the moving knife is rotated from the thread dividing position to the standby position, the moving knife is hooked on the cloth side upper thread and the thread trimmer engaging portion, and is carried to the front side of the shuttle. The upper and lower threads on the cloth side are cut by the respective cutting blades. That is, since the cloth side upper thread and the lower thread located on the front side of the shuttle with respect to the needle side upper thread are further moved to the front side and cut, it is avoided that the needle side upper thread is brought together. You.

This prevents the needle-side upper thread from being cut along with the cloth-side upper and lower threads, and eliminates stitching mistakes and thread waste due to insufficient dimensions of the needle-side upper thread.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS.

First, FIG. 1 shows a partially cutaway plan view of the yarn cutting device, and FIG. 2 shows a cross-sectional view taken along the line II-II of FIG.
In these drawings, a needle plate 12 is attached to the upper surface of the pot base 10 as shown in FIG. This needle plate
Numeral 12 is attached with screws (not shown) screwed into a plurality of screw holes 14 (see FIG. 1) formed in the pot base 10. The needle plate 12 has a needle hole 13 at a position corresponding to a sewing needle 36 described later. The needle hole 13 is indicated by a virtual line in FIG.

Below the needle plate 12, a shuttle 16 is arranged. This pot
The 16 hook shafts 18 are rotatably supported by a bearing metal 20 with respect to the hook base 10. The rotational force of the drive shaft 24 penetrating through the hook base 10 is transmitted to the shuttle shaft 18 through meshing of gears 22 and 26 fixed on the respective shafts.

Further, the base end of the wide picker 28 is attached to the side wall 10a of the pot base 10 by a shaft 30. The wide picker 28 rotates between the solid line position and the virtual line position in FIG. 2 around the axis of the shaft 30 in conjunction with the operation of the plunger 34 by the on / off control of the solenoid 32.

In the hook base 10, a base plate 40 is provided with a bolt 42 in a recess 10b formed slightly lower than the lower surface of the needle plate 12.
Has been fixed by. A fixed knife 44 and a bracket 52 of a thread presser 50 are fixed to the base plate 40 by bolts 48 and 54, respectively. Similarly, a part of the base plate 40 is inserted with an upper end of a female drive shaft 60 rotatably supported by the protrusion 10c of the shuttle base 10 (see FIG. 2). At the upper end of the knife drive shaft 60, the base end of the moving knife 56 is screwed from the upper surface side of the base plate 40.
Has been fixed by. As shown in FIG. 2, a drive arm 64 is connected to the lower end of the knife drive shaft 60, and a link member (not shown) of a knife drive system is connected to the drive arm 64. .

FIG. 3 is an enlarged plan view showing the relationship between the fixed knife 44, the thread presser 50, and the moving knife 56 together with the shuttle 16. As is clear from FIG. 3, the edge of the tip of the fixed knife 44 is a cutting blade 46. The cutting blade 46 is located on the front side of the shuttle 16 and faces the rear of the shuttle 16.

The moving knife 56 has a standby position X indicated by a solid line in FIG. 3 (or FIG. 1) with the axis of the knife drive shaft 60 as a pivot point.
Reciprocatingly rotates within the range between the thread dividing position Y indicated by the virtual line.
The thread presser 50 is a moving knife that has been rotated to the standby position X.
It is arranged at a position where it contacts a part of the lower surface of 56.

The moving knife 56 also has a through hole at its free end.
A cutting blade 58 is formed using the inner peripheral edge of the cutting edge 57. The cutting blade 58 is used to rotate the moving knife 56 from the thread dividing position Y toward the standby position X.
In cooperation with 46, the cloth-side upper thread T2 and lower thread T3, which will be described later, can be cut. The cutting blade 58 of the moving knife 56 is located on the front side of the shuttle 16 when the moving knife 56 rotates to the standby position X.

At both edges of the free end of the moving knife 56, a thread cutting locking portion 66 and a thread dividing locking portion, each of which is cut into a concave shape, are provided.
68 are formed. When the moving knife 56 rotates from the thread dividing position Y toward the standby position X,
The cloth side upper thread T2 and lower thread T3 to be cut are hooked and hooked.
Move to the front side of 16. Further, when the moving knife 56 rotates from the standby position X to the thread dividing position Y, the thread dividing and locking portion 68 hooks a needle-side upper thread T1 described later and moves it to the rear side of the shuttle 16.

FIGS. 4 and 5 schematically show the thread splitting start state and the thread cutting start state, respectively, in external perspective views. 4th
In the state shown in the figure, the rotation of the shuttle 16 causes the upper thread captured by the inspection destination to be carried under the lower thread T3, as is well known.
At this time, the needle-side upper thread T1 connected to the sewing needle 36 is located on the back side of the shuttle 16 with respect to the cloth-side upper thread T2 and the lower thread T3 connected to the sewing end portion of the fabric, and intersects with this.

In the state shown in FIG. 5, the sewing needle 36 is being raised, and the loop formed by the upper threads T1 and T2 is reduced accordingly. By securing this loop as large as possible and cutting the cloth side upper thread T2 and bobbin thread T3 at a position close to the cloth, the needle side upper thread T1 has a sufficient size and sewing error is prevented. .

Therefore, the yarn cutting by the yarn cutting device having the above configuration will be described. First, in the state shown in FIG. 4, after the upper thread is caught by the point of the hook of the shuttle 16, the shuttle 16 is rotated by about 180 °, so that the needle 16 The side upper thread T1 and the cloth side upper thread T2 are separated. At this time, the moving knife 56 starts rotating from the standby position X toward the thread dividing position Y, and the needle-side upper thread T1 is hooked on the thread dividing locking portion 68 of the moving knife 56 and moves to the rear side of the shuttle 16. Carried. That is, the needle-side upper thread T1 is pulled in a direction in which it crosses the cloth-side upper thread T2 and the lower thread T3, which are located on the front side of the shuttle 16 further. Therefore, needle side upper thread T1, cloth side upper thread T2 and lower thread
The thread splitting process is performed properly without causing the thread to be entangled with T3.

At a point shortly before as shown in FIG. 4, the wide picker 28 rotates around the shaft 30 from the solid line position to the virtual line position in FIG. Thereby, the upper thread moving on the front surface of the shuttle 16 in FIG. 4 is secured on the front side of the shuttle 16 by a dimension corresponding to the width of the wide picker 28. As a result, the size of the needle-side upper thread T1 after thread cutting, which will be described next, becomes longer by the amount secured by the wide picker 28, and the above-described sewing mistake is more reliably prevented.

After the thread dividing process, the moving knife 56 is rotated from the thread dividing position Y to the standby position X. Thereby, the cloth side upper thread T2 and the lower thread T3 located on the front side of the shuttle 16 with respect to the needle side upper thread T1.
5 is hooked on the thread cutting locking portion 66 of the moving knife 56 as shown in FIG. Therefore, it is avoided that the needle side upper thread T1 is brought together.
In this process, the lower surface of the fixed knife 44 is
56 passes, and the cloth side upper thread T2 and lower thread T3 are cut by the mutual cutting blades 46, 58.

After the cutting, the thread end of the bobbin thread T3 pulled out from the bobbin (not shown) in the shuttle 16 is connected to the thread presser 50 and the moving knife 56 on the front side of the shuttle 16 in preparation for the next sewing.
It is sandwiched between.

Further, by eliminating the entrainment of the needle-side upper thread T1 during the thread cutting, the fixed knife 44 can be arranged close to the needle hole 13 of the needle plate 12, and the width of the moving knife 56, particularly with the cutting blade 58. The dimension between the thread cutting and locking portion 66 can be set large. Thereby, the length of the needle-side upper thread T1 after the cutting is more sufficiently ensured, and the remaining thread lengths of the upper thread and the lower thread remaining on the fabric side are shortened.

〔The invention's effect〕

As described above, in the present invention, the thread splitting process is performed by transporting the needle-side upper thread to the rear side of the shuttle, and the thread is cut in the process of transporting the cloth-side upper thread and the lower thread to the front side of the shuttle. In addition, it is possible to avoid a situation in which the needle-side upper thread is brought together with the thread at the time of thread splitting or thread cutting, thereby preventing stitching errors or generation of thread waste due to cutting of the needle-side upper thread.

Also, since the thread end of the lower thread pulled out from the bobbin in the shuttle after thread cutting is guided to the front side of the shuttle, sewing can be performed properly even if the thread end is not properly held. Will be

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a plan view showing a part of a yarn cutting device in a cutaway view, FIG. 2 is a sectional view taken along the line II-II of FIG. FIG. 3 is an enlarged plan view of a main member of FIG. 1, FIG. 4 is an external perspective view schematically showing a thread splitting start state, and FIG. 5 is an external view schematically showing a thread cutting start state. It is a perspective view. FIG. 6 is a plan view showing a conventional yarn cutting device in correspondence with FIG. 1, and FIGS. 7 and 8 are schematic diagrams of a conventional yarn splitting start state and a conventional yarn cutting start state, respectively. It is each appearance perspective view represented by correspondence with a figure. 10… Hot base 12… Needle plate 16… Hook 44… Fixing knife 46… Cutting blade 56… Moving knife 58… Cutting blade 66… Thread cutting locking part 68… Thread split locking part T1… Needle side upper thread T2… Cloth Upper needle thread T3 ... Bobbin thread X ... Stand-by position Y ... Thread splitting position

Claims (1)

(57) [Claims] A shuttle is disposed below the needle plate of the shuttle base, and a fixed knife fixed to the shuttle base between the needle plate and the shuttle is rotatable in a range of a thread dividing position and a standby position. A moving knife provided with a moving knife provided, and a sewing knife for cutting a cloth side upper thread and a lower thread at a lower portion of the needle plate by the fixed knife and the moving knife when rotated from the thread dividing position to the standby position. A cutting blade formed on the front side of the shuttle with respect to the fixed knife toward the rear side, and formed at a free end of the moving knife, and when the moving knife is rotated to the standby position. A cutting blade positioned on the front side of the shuttle and a hook formed on an edge of a moving knife, which hooks a cloth-side upper thread and a lower thread to be cut when the knife rotates toward the standby position. Thread trimmer to be moved to the front side of the knives, and also to the opposite side of the thread trimmer to the moving knife A thread dividing hook formed on an edge of the sewing machine, and hooking the needle-side upper thread to move to the rear side of the shuttle when the moving knife rotates toward the thread dividing position; apparatus.