JP4237338B2 - Sewing machine thread trimmer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting device for a sewing machine in which a heating element heated by flowing an electric current is brought into contact with a thread to be cut and melted.
[0002]
[Prior art]
Conventionally, an industrial sewing machine or the like is generally provided with a thread trimming device capable of automatically cutting a thread, and automatically cuts the thread at the end of sewing. As one of the thread trimming devices, for example, there is a device that includes a moving knife and a fixed knife, cuts the thread by moving the thread with the moving knife and sandwiching the handled thread between the moving knife and the fixed knife. However, in such a yarn trimming device, for example, when a twisted yarn composed of a plurality of single yarns is cut, each single yarn is separated from the cut portion after cutting, and the appearance of the cut portion of the yarn is deteriorated. There was a bug. In addition, when the specially coated yarn is cut, there is a problem that the cutting condition of the knife is dulled and a yarn breakage defect occurs. In order to solve such a problem, a thermal fusing type thread trimming device has been developed in which a heating element that generates heat by passing an electric current is brought into contact with the yarn to melt it.
[0003]
FIG. 9 is a bottom view of a conventional hot melt type thread trimming device as viewed from the lower side of the needle plate 101, and FIG. 10 is a sectional view taken along the line XX in FIG. The thread trimming device includes electrical cords 110 and 110, a cord attachment 109, a heating element 103, an insulating plate 107, a catching member 104, a thread trimming lever 112, a thread trimming link 111, and the like. A needle hole guide 102 is fixed to the needle plate 101, and a needle hole 102 c is provided at the center of the needle hole guide 102.
[0004]
The heating element 103 is a plate-like member made of, for example, stainless steel or nichrome, and connects the electric cords 110 and 110 to both terminals 103b and 103c at the rear end, and the other terminal from one terminal 103b through the tip 103a. The shape is such that current flows up to 103c. The tip portion 103a with which the yarn comes into contact is formed with a reduced width so that the amount of heat generated at that portion is increased.
[0005]
The heating element 103 is fixed to the needle plate 101 with a screw or the like (not shown). The tip portion 103a of the heating element 103 is fixed in the vicinity of the periphery of the needle hole in a form along a part of the periphery of the needle hole. The electric cords 110 and 110 are fixed to the needle plate 101 by a cord attachment 109.
[0006]
The catching member 104 is attached to the needle plate 101 so as to be pivotable about the pin 104c, and is provided with a catching portion 104b for catching a thread to be cut forward in the clockwise direction in the figure, while on the rear side. A separating portion 104a for separating the yarn not to be cut is provided.
[0007]
The thread trimming link 111 and the thread trimming lever 112 constitute a link mechanism that transmits the movement of the connecting rod 113 to the capturing member 104. The thread trimming lever 112 is supported at the center so as to be rotatable around the connecting pin 112b, and is connected to the connecting rod 113 so that one end thereof is rotatable around the rotating shaft 112a, and the other end is rotated. It is connected to the thread trimming link 111 so as to be rotatable about the shaft 112c. The other end side of the thread trimming link 111 is connected to the capturing member 104 so as to be rotatable. The connecting rod 113 is connected to a driving mechanism on the sewing machine side that is driven at the time of thread trimming.
[0008]
When the connecting rod 113 is moved in the direction in which the thread is cut when sewing by driving the drive mechanism on the sewing machine side, the movement is transmitted via the thread trimming lever 112 and the thread trimming link 111, and the catching member 104 is counteracted in the drawing. Rotate clockwise. By this rotation, first, the yarn (thread on the needle side of the upper yarn) that the separating portion 104a of the catching member 104 does not cut is further divided, and further, the remaining yarn to be cut (on the fabric side of the upper yarn) on the catching portion 104b. Thread and bobbin thread) are captured.
[0009]
Next, the connecting rod 113 is pulled downward in the figure, and the capturing member 104 rotates clockwise (in the direction of the arrow). The rotated capture member 104 stops at the position shown in the drawing, and the thread captured by the capture unit 104b is brought into contact with the tip 103a of the heating element 103. Immediately after the capture member 104 stops, a current is passed through the heating element 103 to heat it. After heating to a temperature necessary for fusing, the yarn is cut at the tip 103a of the heating element 103.
[0010]
In FIG. 10, reference numeral 21 denotes a sewn product. A gap is provided between the capturing member 104 and the heating element 103 so that the yarn passes therethrough, and the yarns 122 and 123 to be cut are drawn into the gap. The heating element 103 has a high temperature at the distal end portion 103a and a slightly lower temperature on the rear side from the distal end portion 103a. Therefore, the drawn yarns 122 and 123 are cut at the portion T that is in contact with the tip portion 103a.
[0011]
[Problems to be solved by the invention]
However, the above-described thread trimming device stops at the position shown in FIG. 10 after moving while contacting the threads 122 and 123 to the heating element 103 when the capturing member 104 rotates in the direction of the arrow. Since the heating element 103 is heated and the yarns 122 and 123 are melted, the cycle time until the end of thread trimming is extended by the time required for heating the heating element 103.
[0012]
In addition, if the heating element 103 starts to be heated before the capturing member 104 stops at the position shown in FIG. 10, the cycle time for that time can be shortened, but the threads 122 and 123 come into contact with the heating element 103. Therefore, if the time to reach the set temperature for fusing the yarns 122 and 123 varies due to the influence of the outside air temperature, the yarns 122 and 123 will blow out before the stop position of the capturing member 104. There is. In this case, the remaining length of the needle thread after thread trimming becomes short, and there is a problem that a stitch is not formed at the start of the next sewing.
[0013]
The present invention has been made in view of such problems, and an object of the present invention is to provide a thread trimming device for a sewing machine that can shorten the cycle time.
[0014]
Another object of the present invention is to provide a thread trimming device for a sewing machine capable of stable thread trimming so that the remaining length of the needle thread after thread trimming is constant.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a heating element that generates heat by passing an electric current, and a capturing member that captures a thread to be cut and moves it to a predetermined thread trimming position, the cutter is cut at the thread trimming position. In the thread trimming device for a sewing machine that melts the power yarn by bringing it into contact with the heating element, the heating element is disposed above the path where the capturing member captures the thread to be cut and then moves to the thread trimming position. The portion of the yarn to be cut that is located below the heating element after the tip of the yarn to be cut that is moved by the catching member passes through the heating element and reaches the yarn cutting position. There is provided a thread trimming device for a sewing machine provided with contact blocking means for preventing contact between the sewing machine and the heating element. Since the contact between the yarn and the heating element is prevented by this contact blocking means, the yarn does not touch the heated heating element when approaching the yarn to the thread trimming position, and therefore the yarn reaches the thread trimming position. It can be moved without being cut before.
[0016]
For example, the blocking means is disposed between the catching member and the heating element and moves in synchronism with the catching member in the vicinity of the thread trimming position.
[0017]
Before the yarn to be cut reaches the yarn cutting position, an electric current can be passed through the heating element to heat it.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a bottom view of a state in which a thread trimming device for a sewing machine according to an embodiment of the present invention is in a standby position, as viewed from the lower side of a needle plate 1. 2 is an enlarged bottom view of the main part of FIG. 1, FIG. 3 shows the main part of the apparatus of FIG. 1, (A) is a bottom view showing the needle hole guide 2 and the heating element 3, and (B). FIG. 3 is a side view showing the needle hole guide 2, and FIG. 3C is a side view showing the heating element cover 5 as seen from the direction C of FIG. 2.
[0019]
In these drawings, the thread trimming device of the present embodiment is attached to a needle plate 1 of a sewing machine. This thread trimmer includes a heating element 3, a capture member 4, a heating element cover 5 (contact blocking means), a heating element cover spring 6, insulating plates 7 and 8, cord attachments 9, electric cords 10 and 10, thread trimming links. 11 and a thread trimming lever 12 and the like.
[0020]
A needle hole 2 c is provided at the center of the needle hole guide 2 fixed to the needle plate 1. The needle hole guide 2 has a thread guiding role during stitch knotting and thread trimming. A notch 2b is formed in the boss portion 2a. This notch 2 b is for guiding the yarn to the heating element 3 reliably, and is provided at a position facing the heating element 3 when the needle hole guide 2 is attached to the needle plate 1.
[0021]
The heating element 3 is a plate-like member made of, for example, stainless steel or nichrome, and connects the electric cords 10 and 10 to both terminals 3b and 3c at the right end, and the other terminal 3c from one terminal 3b through the tip 3a. It is formed in a shape that allows current to flow. The tip 3a with which the yarn comes into contact is formed with a reduced width so that the amount of heat generated at that portion is increased.
[0022]
The heating element 3 is fixed to the needle plate 1 via an insulating plate 7 with screws or the like (not shown). Moreover, the front-end | tip part 3a of the heat generating body 3 is being fixed to the vicinity of the periphery of this needle hole in the form along a part of periphery of the needle hole 2c. The electric cord is fixed to the needle plate 1 by a cord attachment 9.
[0023]
The catching member 4 is attached to the needle plate 1 so as to be rotatable around a pin 4c, and provided with a catching portion 4b for catching a thread to be cut forward in the clockwise direction in the drawing, on the rear side. A separating portion 4a for separating the yarn not to be cut is provided. The tip 3a of the heating element 3 is disposed above the path where the catching portion 4b catches the yarn to be cut and then moves to the yarn trimming position described later.
[0024]
The heating element cover 5 is disposed between the capturing member 4 and the heating element 3 and is rotatable about the pin 4c. The heating element cover 5 is formed with a protruding portion 5a protruding downward on the side far from the needle hole 2c. The heating element cover 5 is positioned below the heating element among the yarns to be cut before reaching the thread trimming position after the leading end of the yarn to be cut drawn by the catching portion 4b passes through the heating element. This is to prevent the portion and the heating element 3 from contacting each other.
[0025]
One end of the heating element cover spring 6 is fixed to a spring fitting 6a fixed to the needle plate 1, and the other end is provided so as to contact the heating element cover 5. The heating element cover 5 is centered on the pin 4c. Always pressing in the counterclockwise direction. When the heating element cover 5 is pressed by the heating element cover spring 6 in this way, in the state shown in FIGS. 1 and 2, the protruding portion 5a of the heating element cover 5 contacts the capturing portion 4b, so that the capturing member 4 also generates heat. The body cover 5 and the body cover 5 are pressed in the same counterclockwise direction.
[0026]
The insulating plate 7 is for insulating the heating element 3 and the heating element cover 5, and is provided between the heating element 3 and the heating element cover 5. Moreover, it is for insulation of the needle plate 1 and the heat generating body 3, and the insulating plate 8 is provided between the needle plate 1 and the heat generating body 3 (see also FIG. 8). Since the throat plate 1 is directly touched by an operator, these insulating plates 7 and 8 are provided to prevent an electric shock during energization.
[0027]
The cord attachment 9 is for connecting the heating element 3 and the electric cords 10 and 10 and is fixed to the needle plate 1. The cord attachment 9 is made of an insulator and is insulated from the needle plate 1. The electric cords 10 and 10 are media for supplying a current necessary for heating the heating element 3, and are connected to a transformer (not shown).
[0028]
The thread trimming link 11 and the thread trimming lever 12 constitute a link mechanism that transmits the movement of the connecting rod 13 to the capturing member 4. The thread trimming lever 12 is supported at the center so as to be pivotable about the coupling pin 12b, and is connected to the coupling rod 13 with one end being pivotable about the pivot shaft 12a, and being threaded at the other end. The cut link 11 is connected so that the one end side can rotate. The other end side of the thread trimming link 11 is connected to the capturing member 4 so as to be rotatable about a rotation shaft 11a. The connecting rod 13 is connected to a driving mechanism on the sewing machine side that is driven at the time of thread trimming.
[0029]
The thread trimming device according to the present embodiment is a unit that can be attached to and detached from the sewing machine including the needle plate 1, and fixes the needle plate 1 to the sewing machine frame through a plurality of screw holes 1a, 1a,. At the same time, by connecting the connecting rod 13 to the thread trimming lever 12, the thread trimming device can be attached to the sewing machine. When this thermal cutting type thread trimming device is not used, it can be handled by removing the connecting rod 13 from the thread trimming lever 12, removing the device from the sewing machine together with the needle plate 1, and attaching another needle plate to the sewing machine. ing.
[0030]
The operation of the sewing machine thread trimming apparatus having the above configuration will be described. During sewing, on the basis of the thread trimming signal, a heating signal is sent to the transformer before the thread is actually cut. Due to this heating signal, a current is passed through the heating element 3 via the electric cords 10, 10, and heating of the tip 3 a of the heating element 3 starts. When the above thread trimming signal is sent, the thread trimming drive mechanism on the sewing machine side is driven. As a result, the connecting rod 13 is pushed upward in FIG. 1, and the catching member 4 rotates counterclockwise via the thread trimming lever 12 and the thread trimming link 11. At this time, since the heating element cover 5 is pressed against the capturing member 4 by the heating element cover spring 6, it rotates together with the capturing member 4.
[0031]
In this way, while the capturing member 4 is rotated counterclockwise, the heating element cover 5 stops at a position where the heating element cover 5 contacts the boss 2a of the needle hole guide 2 and hides the heating element 3. FIG. 4 is a bottom view showing a state in which the catching member 4 is further rotated counterclockwise after the heating element cover 5 comes into contact with the boss portion 2a. At this time, the yarn cutting device according to the present embodiment is In the capture position. In the illustrated example, the boss portion 2a of the needle hole guide 2 is a stopper of the heating element cover 5, but a stopper may be provided separately from the boss portion 2a. Thereafter, the capture member 4 continues to rotate counterclockwise. By this rotation, first, the thread 23b (upper thread on the needle side) that is not cut by the separating portion 4a of the capture member 4 is further divided, and further, the capture portion 4b. The remaining yarns 22 and 23a to be cut (the lower yarn and the upper yarn on the fabric side) are captured. In this way, the yarns 22 and 23a to be cut and the yarn 23b that is not cut are separated.
[0032]
Next, the connecting rod 13 is pulled downward in the figure, and rotates clockwise while catching the yarns 22 and 23a to be cut by the catching member 4 by the catching portion 4b. FIG. 5 is a bottom view showing a state in which the capturing member 4 is rotated clockwise and comes into contact with the protrusion 5 a of the heating element cover 5 again. At this time, the tip 3a of the heating element 3 has already been heated, and the yarn can be melted. On the other hand, since the heating element cover 5 is interposed between the yarns 22 and 23a to be cut and the heating element 3, even if the tips of the yarns 22 and 23a to be cut pass through the heating element, the yarn 22 at this stage , 23a is not cut because the portion located below the heating element does not contact the heating element.
[0033]
Thereafter, the catching member 4 is rotated in the clockwise direction together with the heating element cover 5, reaches the thread trimming position shown in FIGS. 7 is an enlarged bottom view showing the main part of FIG. 6, and FIG. 8 is a sectional view taken along the line ZZ of FIG. When reaching the above-described thread trimming position, the portions of the yarns 22 and 23a to be cut that are located below the heating element touch the tip 3a of the heating element 3, and the yarns 22 and 23a are instantaneously fused. The heating element 3 has a high temperature at the tip 3a, but is slightly lower on the rear side from the tip 3a. Therefore, the drawn yarn 22 is cut at the portion T that is in contact with the tip 3a.
[0034]
As is clear from the above description, when the thread trimming device is in the catch position, the heating element cover 5 is stopped in contact with the boss portion 2a as a stopper, but the thread trimming device is in another position, that is, waiting. When in the position and the thread trimming position, the heating element cover 5 pressed against the capturing member 4 by the heating element cover spring 6 rotates integrally with the capturing member 4 around the pin 4c. In other words, when the thread trimming device is in the standby position and the thread trimming position, the heating element cover 5 rotates around the pin 4 c in synchronization with the catching member 4. The heating element cover 5 prevents contact between the threads 22, 23a and the heating element 3 until the yarns 22, 23a to be cut reach the thread cutting position shown in FIGS. Therefore, even if an electric current is supplied to the heating element 3 and heated in advance, the yarns 22 and 23a are not cut at positions other than the yarn cutting position.
[0035]
Further, at the thread trimming position, the heating element cover 5 rotates around the pin 4c in synchronization with the catching member 4, so that the timing at which the threads 22, 23a contact the heating element 3 at the thread trimming position is always constant. It becomes possible to do. Therefore, the remaining length of the needle thread after thread trimming can be made constant, and stable thread trimming is possible.
[0036]
As shown in FIG. 8, in order to allow the heating element 3 to be arranged closer to the sewing product, the needle plate 1 is provided with a groove 1b in the thickness direction thereof. The heating element 3 is fitted and arranged in 1b.
[0037]
【The invention's effect】
According to the first aspect of the present invention, the contact blocking means for preventing contact between the yarn to be cut and the heating element until the yarn to be cut moved by the catching member reaches the yarn cutting position is provided. Therefore, the yarn can be moved closer to the yarn trimming position without touching the yarn with the heated heating element until the yarn trimming position is reached. Accordingly, as described in the third aspect, since the current to be heated can be supplied to the heating element before the yarn to be cut reaches the yarn cutting position, the cycle time can be shortened.
[0038]
According to a second aspect of the present invention, the blocking means is disposed between the catching member and the heating element and is configured to move in synchronization with the catching member in the vicinity of the thread trimming position. The timing of fusing by touching the heating element can be made constant. Therefore, the remaining length of the needle thread after thread trimming can be made constant, and stable thread trimming is possible.
[Brief description of the drawings]
FIG. 1 is a bottom view of a state in which a thread trimming device of a sewing machine according to an embodiment of the present invention is in a standby position, as viewed from below a needle plate.
FIG. 2 is an enlarged bottom view showing the main part of FIG.
3 shows the main part of the apparatus of FIG. 1, (A) is a bottom view showing a needle hole guide and a heating element, (B) is a side view showing the needle hole guide 2, and (C) is a heating element cover 5; FIG. 3 is a side view seen from the direction C in FIG. 2.
4 is a bottom view showing a state in which the apparatus of FIG. 1 is in a capturing position, and a state in which a capturing member is further rotated counterclockwise after a heating element cover comes into contact with a boss portion. FIG.
FIG. 5 is a bottom view showing a state in which the capturing member of the apparatus of FIG. 1 is rotated in the clockwise direction and again comes into contact with the protruding portion of the heating element cover.
6 is a bottom view showing a state in which the apparatus of FIG. 1 is in a thread trimming position. FIG.
FIG. 7 is a bottom view showing the main part of FIG. 6 in an enlarged manner.
8 is a cross-sectional view taken along line ZZ in FIG.
FIG. 9 is a bottom view of a conventional thread trimming device viewed from below the needle plate.
10 is a cross-sectional view taken along line XX in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Needle plate 1b Groove 2 Needle hole guide 2a Boss part 2b Notch 2c Needle hole 3 Heat generating body 3a Tip part 3b, 3c Terminal 4 Capture member 4a Scatter part 4b Capture part 4c Pin 5 Heat generating body cover (contact prevention member)
5a Protruding part 6 Heating element cover spring 6a Spring fixture 7, 8 Insulating plate 9 Cord fixture 10, 10 Electrical cord 11 Thread trimming link 11a Rotating shaft 12 Thread trimming lever 12a Rotating shaft 12b Connecting pin 13 Connecting rod 21 Sewing Item 22 Lower thread (thread to be cut)
23a Upper thread on the fabric side (thread to be cut)
23b Needle-side upper thread (thread that is not cut) 101 Needle plate 102 Needle hole guide 102c Needle hole 103 Heating element 103a Tip 103b, 103c Terminal 104 Capture member 104a Scatter part 104b Capture part 104c Pin 107 Insulation plate 109 Cord attachment 110 , 110 Electric cord 111 Thread trimming link 112 Thread trimming lever 112a Rotating shaft 112b Connecting pin 112c Rotating shaft 113 Connecting rod 122, 123 Thread to be cut

Claims (3)

A heating element that generates heat by passing an electric current;
A capture member that captures the thread to be cut and moves it to a predetermined thread trimming position;
In a thread trimming device for a sewing machine that melts a thread to be cut at the thread trimming position by bringing it into contact with a heating element,
The heating element is disposed above a path where the capturing member moves to the thread trimming position after capturing the thread to be cut.
The portion of the yarn to be cut that is located below the heating element after the tip of the yarn to be cut that is moved by the catching member passes through the heating element and reaches the yarn cutting position. A thread trimming device for a sewing machine provided with contact blocking means for preventing contact between the heating element and the heating element. The sewing machine thread trimming device according to claim 1,
A thread trimming device for a sewing machine, wherein the contact preventing means is disposed between the catching member and the heating element and moves in synchronism with the catching member in the vicinity of the thread trimming position.   3. A thread trimming apparatus for a sewing machine according to claim 1, wherein a current is supplied to the heating element to heat the thread to be cut before the thread to be cut reaches the thread trimming position. .

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