JPS6248512B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a horizontal hook type sewing machine, and more particularly to a horizontal hook type sewing machine equipped with an automatic thread cutting device that simultaneously cuts upper and lower threads.

For sewing machines equipped with an automatic thread cutter, the upper and lower threads remaining on the back side of the fabric after the thread has been cut should be as short as possible, and the stitches should be made so that skipped stitches do not occur in the first stitch of the next sewing. In addition, it is necessary to pull out the necessary amount of needle thread remaining on the needle side after thread trimming.

For this reason, conventionally, when the hook part at the tip of the hook moved farthest from the needle, when the hook turned more than 180 degrees,
The upper thread was pulled out to the maximum by passing through the outer circumference of the bobbin case, and a movable knife for sorting the upper thread was formed so as to protrude into the upper thread loop.

At this time, in the horizontal hook type sewing machine, as shown in FIGS. 8 and 9, the needle thread loop 126 that goes around the outer periphery of the bobbin case 40 is parallel to the surface of the throat plate 28, and the needle hole of the feed dog 24 is Upper thread 124 that should be cut directly below the needle, and upper thread 12 that should not be cut so as to remain on the needle.
2 are in close contact with each other, and it is extremely difficult to insert the tip of the movable knife 64 into them.
The upper threads 122 and 124 are mis-captured, and the lower thread 128 which intersects just below the needle hole 26 of the feed dog 24 is mis-captured, making it impossible to perform complete thread trimming. For this reason, the upper thread is usually 12
The movable knife 64 that selects and captures the needle thread 124 and the bobbin thread 128 is operated below the flat part of the upper surface of the bobbin case 40, and the movable knife is operated at a position where the loop 126 of the needle thread that goes around the outer circumference of the bobbin case 40 is expanded as much as possible. As a result, the distance between the movable knife 64 and the needle hole 26 of the feed dog 24 increases, and the thread leg remaining on the back side of the cloth after thread cutting becomes longer, which reduces the commercial value of the sewn product. Not only did this result in a decrease in the number of threads, but it also required the thread to be trimmed again based on subsequent input. Furthermore, since the movable knife 64 is positioned downward, the movable knife 64 and the tip of the hook 38 may come into contact and damage the sewing machine.
It is also necessary to move the position downward, which also causes problems in sewing.
In addition, in the conventional method, since the movable knife 64 is located below the flat surface of the bobbin case 40, the waiting blade 10 engages with the movable knife 64 to cut the thread.
The position 0 needs to be provided away from the needle hole 26 of the feed dog 24, which does not come into contact with the upper surface of the hook portion 42 at the tip of the hook 38, and as a result, the position where the movable knife 64 and the standby blade 100 are engaged, that is, the thread cutting The position of the feed dog 24 was further away from the throat plate 28, and the thread leg remaining on the back side of the cloth after the thread was cut was also abnormally long, detracting from the commercial value of the sewn product. Furthermore, the movable knife 64 needs to operate when the needle threads 122, 124 turn around the outer circumference of the hook 38.
The sewing machine is driven by transmitting the thread trimming signal, and the hook 38
The operation of the movable knife 64 is waited until the movable knife 64 has rotated approximately 180 degrees, and the movable knife 64 is returned to its original position during a very short cycle after the movable knife 64 is operated and the take-up is at the top. Various problems have arisen, such as the high operating speed of the scalpel 64, which creates strain on the drive transmission path and even causes damage to the sewing machine.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a hook-shaped sewing machine that does not make thread cutting errors, can cut threads at appropriate lengths, and can cut threads smoothly and reliably. The purpose of the present invention is to provide an automatic thread cutting device.

In order to achieve the above object, the present invention cuts the upper thread and the lower thread by engaging a movable knife that is horizontally movable with respect to the throat plate surface and a standby blade in response to a thread trimming activation signal. In a horizontal hook-type thread trimming machine, the needle bar is raised to create a vertical loop of upper thread at the bottom of the needle hole of the feed dog, and the pointed head is inserted into the upper thread and lower thread that need to be trimmed. The present invention is characterized in that a movable knife for sorting and capturing threads and a waiting blade that engages with the movable knife to cut the thread are located above the upper surface of the bobbin case, and the movable knife is capable of linear operation.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

The present invention is shown in FIGS. 1 to 7, and the same members as in FIGS. 8 and 9 will be described with the same reference numerals.

10 is a bed, 12 is a sewing machine arm provided with a needle bar 14 that moves back and forth according to the sewing cycle, and needles 16 are inserted at a predetermined pitch at the lower end of the needle bar 14.
A needle holder 18 for attaching the holder is detachably attached. A lower shaft 20 is rotatably supported by a bearing 22 provided on the bed 10, and is linked by a timing belt (not shown) with an upper shaft rotatably supported by the sewing machine arm 12. It rotates in synchronization with this upper shaft. Reference numeral 24 denotes a feed dog that feeds the work cloth together with the presser foot 25, and is mounted so as to be adjustable in position on a feed base that swings vertically and horizontally in accordance with the sewing cycle of a sewing machine (not shown). . Also, this feed dog 24
A needle hole 26 through which the needle 16 passes is provided in both of the overhanging portions. 28 is a set screw 30 on the top surface of the bed 10.
This is the throat plate that is removably attached to the feed dog 2.
A feed dog groove 32 is provided so that 4 can be operated by a predetermined amount. Reference numeral 34 denotes a swing stand attached to the bottom surface of the bed 10 so that its position can be adjusted.
A shaft portion 39 of a hook 38 is supported by a bearing 36 provided in the bearing 36 . This hook 38 is attached horizontally to the surface of the bed 10, and its outer periphery is designed to catch an upper thread loop 126 formed near the needle hole 26 of the needle 16 and pass around the outer periphery of a bobbin case 40, which will be described later. A hook portion 42 is provided for making the connection. The tip of the side peripheral portion 44 of this hook portion 42 is formed into a sharp sword-point shape, and a bearing groove 46 is provided inside the hook 38.
Reference numeral 48 denotes a small screw gear attached to the vicinity of the middle of the shaft portion 39 of the hook 38 with a set screw 50, and this small screw gear 48 is connected to the large screw gear 5 attached to the lower shaft 20.
2, and the rotation of the lower shaft 20 gives the hook 38 a predetermined rotation. 54 is the hook stand 34
The camshaft is rotatably supported by a bearing 56 provided in the camshaft, and a screw gear 58 installed in the middle meshes with the machine screw gear 48 of the hook 38, and a set screw 60 is attached to the end to cut the thread. A hook 62 is attached. This thread cutting hook 62 operates the movable knife 64 only during automatic thread cutting, and is provided with a cam groove 66. Reference numeral 68 denotes a guide stand having a sliding groove, and is attached to the peripheral surface of the hook stand 34 side with a cover plate 69 with a set screw 70.

Reference numeral 72 denotes a scalpel table, and a sliding portion 74 located in the sliding groove of the guide table 68 is provided. A movable knife 64 is detachably attached to the knife table 72 with a set screw 75, and a connecting link 78 is attached to the end of the sliding portion 74 with a stepped screw 76. Reference numeral 80 denotes a drive arm for driving the knife table 72, which is attached to a shaft 82 which is supported by the hook table 34, and whose end portion is connected to the connecting link 78, and when the shaft 82 rotates, the knife table 72 is moved. is operated in parallel to the hook stand 34, so that the movable knife 64 can plunge into the needle thread loop 126 formed at the lower surface of the needle hole 26 of the feed dog 24 during thread trimming. 84 is a cam arm attached to the shaft 82, and a joint arm 86 is swingably connected to the cut portion of the cam arm with a pin, and the cam groove 66 of the thread trimming cam 62 is attached to the tip of the joint arm 86. A roller 88 that engages with is rotatably mounted. Reference numeral 90 denotes a rotary solenoid attached to the cam arm 84, and by the elastic force of a spring provided in the solenoid 90, the roller 88 of the joint arm 86 is activated by the cam of the thread cutting cam 62 when the rotary solenoid 90 is demagnetized. It is located away from the groove 66 and operates the joint arm 86 by excitation, causing the roller 88 to enter and engage the cam groove 66, thereby converting the rotation of the thread trimming cam 62 into the operation of the movable knife 64. be.

The tip of the movable knife 64 is connected to the needle hole 26 of the feed dog 24.
It has a pointed shape so that it can easily penetrate into the upper thread loop 126 created at the lower part, and a hook part 94 and a blade part 96 are located in the middle of the sloped part 92 slightly away from the tip.
is provided. The hook portion 94 is connected to the upper thread loop 1.
26 and sort out the needle thread 124 to be cut and the needle thread 122 to be removed to the outside of the blade surface of the blade part 96 in order to leave it on the needle 16 side after thread cutting at the slope part 92, and then
As the movable knife 64 advances, the upper threads 122, 124
The upper thread 122 is pulled out from the bobbin winding source, and a predetermined amount of the lower thread 128 is pulled out from the lower thread outlet hole 98 of the bobbin case 40. In particular, in the present invention, the point of the movable scalpel 64 and the blade part 108 of the standby blade 100 are located above the flat surface of the upper surface of the bobbin case 40, and at the position closest to the needle hole 26 of the feed dog 24. It is designed so that it becomes This is the needle thread 1 that remains on the back side of the fabric after thread trimming.
This is to make the thread leg 22 as short as possible. 1
00 is a standby blade, which is fixed with a set screw 106 to a cutter mount 104 which is attached to the hook stand 34 with a set screw 102 so that the height can be adjusted.
4 moves forward, and the blade part 96 of the movable knife 64 and the waiting blade 1
00, the upper thread 124 and the lower thread 12
8 cuts are made. Reference numeral 110 denotes an inner hook, which is rotatably supported by a race groove inside the hook 38, and a fitting shaft portion 114 is provided in the center to hold a bobbin 112 wound with a large amount of bobbin thread 128. A rotation stopper 118 is provided on the side wall portion to engage with a stopper groove 116 provided at one location of the throat plate 28, and the inner hook 110 is formed to be prevented from rotating when the hook 38 is rotated. . Bobbin case 4
0 is fitted onto the fitting shaft portion 114 of the inner hook 110, and then is prevented from coming off from the inner hook 110 by a latch 120. The bobbin thread 128 wound around the bobbin 112 stored in the inner hook 110 is stored in the bobbin case 40.
The upper thread 122 is taken out from the lower thread exit hole 98 provided in the flat part of the upper surface, and is threaded through the sewing machine sewing cycle.
124 and is drawn out to the upper surface of the throat plate 28 through the needle hole 26 of the feed dog 24 to form a seam.

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

When the sewing machine operation is stopped by operating the pedal provided at the bottom of the table, a signal is sent to the control circuit of the motor for stopping the needle setting position, and the sewing machine operation stops with the needle bar 14 lowered to the lowest position. .

Thereafter, when the pedal is operated to perform automatic thread trimming, the sewing machine starts rotating at a low speed until it slightly passes the uppermost position of the needle bar 14. When the needle bar 14 rises slightly during the rotation of the sewing machine, the needle 16 and the hook portion 42 of the hook 38 match below the needle hole 26 of the feed dog 24, and the needle hole of the needle 16 aligns with the hook portion 42 of the hook 38, as in a normal sewing machine. Needle thread loop 1 created around 26
26, and the hook part 42 sequentially catches the upper thread as it rotates around the outer periphery of the bobbin case 40 as the hook 38 rotates. , Upper thread 12 left on the needle 16 side
2 and the upper thread 124 to be cut are tensioned to the maximum,
As shown in FIG. 7, the needle hole 2 of the feed dog 24 is
6, a vertical needle thread loop 126 is formed. At this time, the rotary solenoid 90 is energized, the joint arm 86 is activated, and the roller 88
is thrust into engagement with the cam groove 66 of the thread cutting cam 62.

The cam shaft 54 also rotates as the sewing machine rotates, and the knife table 72 is operated by the drive arm 80 and the connecting link 78 via the roller 88 according to the amount of displacement of the thread trimming cam 62. The tip of the needle thread enters into the needle thread loop 126, and as described above, as the movable knife 64 advances, its sloped portion 92 guides the needle thread 124 to be cut to the hook portion 94,
Needle thread 12 on the side left on the needle, which has nothing to do with the waiting blade 100
2 is guided to the outside of the movable knife 64 so that it comes off from the blade surface part 108 of the waiting blade 100 when it engages with the waiting blade 100, and the upper thread 124 is guided into the hook part 94 by the slope part 92, and the needle thread 124 is guided into the hook part 94 by the slope part 92 and removed from the cutting blade 100. 100, so as to come into contact with the blade surface portion 108 of the waiting blade 100.

Furthermore, as the movable knife 64 advances, the upper thread 122 is pulled out from the bobbin winding source by the hook part 94 so as not to cause skipped stitches in the sewing after thread trimming, and then the upper thread 122 is pulled out from the bobbin thread exit hole 98 of the bobbin case 40 by the feed dog. The lower thread 128 reaching the needle hole 26 of No. 24 is captured by the hook portion 94 and pulled out. After sufficiently taking out the upper thread 122 and lower thread 128, the blade part 96 of the movable knife 64 and the waiting blade 1 are removed.
00 are engaged with each other, and only the upper thread 122 and bobbin thread 128, which are guided by the hook part 94 and located approximately in the center between the movable knife 64 and the blade part 96, are transferred to the movable knife 64 directly below the needle hole 26 of the feed dog 24. and the blade surface part 1 of the waiting blade 100
Since the thread is cut when the needle thread 08 is engaged, the needle thread 124 remaining on the back side of the cloth after thread cutting can be shortened to the minimum possible length.

In the present invention, when the sewing machine starts driving, the hook portion 42 of the hook 38 captures the needle threads 122 and 124, and the needle threads 122 and 124 are vertically threaded by the side circumferential portion 44 of the hook portion 42 directly below the needle hole 26 of the feed dog 24. Needle thread loop 12 created
6, the pointed head of the movable scalpel 64 and the blade surface part 108 of the waiting blade 100 can be positioned above the flat upper surface part of the bobbin case 40, and in particular, the waiting blade 100 comes into contact with the hook 38. There is no danger,
It can be installed at the position closest to the needle 16, and the thread leg remaining on the back side of the cloth after thread cutting can be minimized.

Furthermore, in the present invention, the needle thread 1 is cut by the hook portion 42 of the hook 38 immediately after the sewing machine starts rotating in response to a thread trimming signal.
Since the movable scalpel 64 operates when capturing 22, 124, it is possible to lengthen the time required for thread trimming, and as a result, there is no need for sudden operation of each thread trimming mechanism, and the operation is extremely smooth. As a result, we can expect longer life and stable operation of the entire sewing machine.

As described above, the present invention not only improves operational stability and workability, but also extends the life of the sewing machine itself.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway front view including the main parts of the sewing machine, Figure 2 is a side view of the same, Figure 3 is an enlarged plan view of the same,
Figure 4 is an enlarged front view of the main parts, and Figure 5 is the same as in Figure 4.
6 is an enlarged front view showing the upper thread being caught by the movable knife, FIG. 7 is a sectional view taken along the line -- in FIG. 6, and FIGS. 8 and 9 show the conventional device. FIG. 8 is a plan view, and FIG. 9 is a sectional view taken along the line -- in FIG. The same members in each figure are given the same reference numerals, 14 is the needle bar, 24 is the feed dog, 26 is the needle hole, 28 is the throat plate, 4
0 is a bobbin case, 64 is a movable knife, 100 is a waiting blade, 122 is an upper thread to be left on the needle side, 124 is an upper thread to be cut, 126 is an upper thread loop, and 128 is a lower thread.

Claims (1)

[Claims] 1 In a horizontal hook-type thread trimming machine that trims upper and lower threads by engaging a movable knife that can move horizontally with respect to the throat plate surface and a standby blade in response to a thread trimming operation signal, the needle bar is raised. A movable knife that inserts its pointed head into the needle thread loop created vertically on the lower surface of the needle hole of the feed dog to selectively capture the needle thread and bobbin thread that require thread cutting; A horizontal hook type thread trimming sewing machine characterized in that a waiting blade that engages with a movable knife to cut thread is located above the top surface of a bobbin case, and the movable knife can be operated in a straight line.