JP4474003B2 - 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 is provided with a thread trimming device and automatically cuts a 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 thread trimming device, when cutting a twisted yarn composed of a plurality of single yarns, there is a problem that after cutting, each single yarn is separated from the cut portion, and the appearance of the cut portion of the yarn is deteriorated. there were. Further, 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 problems, there has been provided a thermal fusing type thread trimming device in which a heating element that generates heat by passing an electric current is brought into contact with the yarn for fusing.
[0003]
7 and 8 show an example of such a thermal fusing type yarn cutting device. This thread trimming device was proposed by the present applicant in Japanese Patent Application No. 11-119794. By driving a solenoid for thread trimming (not shown), the connecting rod 11 is pushed and moved upward in the figure, and movement is transmitted through the catching lever 9 and the catching link 8 so that the catching member 7 is counterclockwise in the figure. Rotate to. This counterclockwise rotation further divides the yarn (the needle-side upper thread 30a) that the yarn separating portion 7a of the catching member 7 does not cut, and further the remaining upper and lower yarns (cloth-side on the fabric side) to be cut in the catching portion 7b. The upper thread 30b and the lower thread 31) are captured.
[0004]
Next, the connecting rod 11 is pulled and moved downward in the figure, and the capturing member 7 rotates in the clockwise direction. As shown in FIG. 8, the upper and lower threads 30, 31 to be cut are guided into the notch 5 a of the lower insulating plate 5 while bringing the upper and lower threads 30, 31 to be cut into contact with the tip 4 a of the heating element 4 by the clockwise rotation of the capturing member 7. To do. After the capture member 7 is stopped at the clockwise rotation end shown in FIG. 7, a heating signal is sent to the transformer, a current is passed through the heating element 4 via the electric cords 2, 2, and the tip of the heating element 4 4a is heated. And when predetermined time passes, the up-and-down thread | yarns 30 and 31 which were contacting the front-end | tip part 4a of the heat generating body 4 are cut | disconnected in a predetermined | prescribed cutting location. If the rotation angle of the main shaft when the needle bar is at the top dead center position is 0 degrees and the rotation angle of the main shaft when the needle bar is at the bottom dead center position is 180 degrees, the rotation angle of the main shaft is around 50 degrees. When it becomes, the sewing machine is stopped. When the sewing machine is stopped, the catching member 7 is moved to the position shown in FIG. 8 (yarn cutting / standby position).
[0005]
[Problems to be solved by the invention]
However, in the conventional thermal cutting type thread trimming device, when the yarn is cut, the catch member 7 is stopped at a position away from the yarn cutting portion of the heating element 4 as shown in FIG. In some cases, 30a may come into contact with the yarn fusing part of the heating element 4 and cut.
[0006]
Originally, it is necessary to melt only the upper thread (upper thread on the cloth side) 30b between the catching member 7 and the heating element 4 to secure the upper thread (upper thread on the needle side) 30a remaining on the needle side. However, if the needle-side upper thread 30a comes into contact with the thread fusing portion of the heating element 4 in this way, the upper thread 30a does not remain on the needle side, so that a stable seam can be formed at the start of the next sewing. There was a problem that it was not possible.
[0007]
[Means for Solving the Problems]
According to the present invention in order to solve the above problems, a sewing needle that moves up and down in conjunction with the sewing machine main shaft, a needle plate for supporting the workpiece by reciprocating movement beneath the needle plate, to be cut Of the upper thread and lower thread on the side to be sewn, the upper thread and lower thread on the side continuous with the sewing object are captured on one side in the reciprocating direction , and the upper thread on the side continuous with the needle is captured on the other side A catching means for catching on, a boss portion fixed to the needle plate to form a needle hole, projecting downward at a lower end edge of the needle hole, and a thread guiding direction of the catching means A needle hole guide having a notch formed at a lower end of the boss part, and a lower surface of the needle plate so that a tip part is disposed on the thread guide direction side of the needle hole and in the vicinity of the needle hole guide. And a heating element that generates heat when an electric current flows, and is captured by the capturing means. In a thread trimming device for a sewing machine, in which the upper and lower threads brought into contact with the tip of the heating element are fused, the catching means is moved to a standby position and a forward movement in the opposite direction across the needle hole with respect to the standby position. And the one side surface and the other side surface of the heating element in the yarn guiding direction, the position of the one side surface being positioned on the yarn guiding direction side of the leading end portion of the heating element. And a moving means for stopping the movement to an intermediate position that hides the tip of the heating element, and when the current flows through the heating element, the capturing means is The needle thread is stopped at an intermediate position, the upper thread connected to the sewing object is brought into contact with the tip of the heating element by the catching means, and the upper thread connected to the raised needle contacts the tip of the heating element. Configured not to. The upper thread on the needle side is not melted because it does not contact the heating element.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings of FIGS.
[0009]
FIG. 1 is a bottom view of a thread trimming device for a sewing machine according to an embodiment of the present invention as viewed from the lower side of a needle plate 10 and shows a state where a catching member is in an intermediate position. FIG. 2 is an enlarged view of the vicinity of the needle hole guide of FIG. FIG. 3 is an explanatory view of a formation position of a notch portion of the needle hole guide of FIG. 4 is a cross-sectional view in the ZZ direction of FIG. FIG. 5 is an exploded perspective view showing the thread trimming drive mechanism of the apparatus of FIG. FIG. 6 is a bottom view showing a state where the capturing member of the apparatus of FIG. 1 is in the standby position.
[0010]
The thread trimmer 1 according to this embodiment includes an electric cord 2, 2, a cord attachment 3, a heating element 4, insulating plates 5, 6, a capture member 7, a capture link 8, a capture lever 9, etc. It is a unit constructed by attaching to. The thread trimming device 1 is a unit that can be attached to and detached from the sewing machine including the needle plate 10. And when this thread trimming device 1 is not used, it can be handled by removing the connecting rod 11 from the catching lever 9 and removing the needle plate 10 together with the needle plate 10 and attaching another needle plate to the sewing machine.
[0011]
Reference numeral 13 in FIG. 4 denotes a sewing needle that moves up and down in conjunction with a sewing machine main shaft (not shown). A needle hole guide 12 having a boss portion facing downward is fixed to the needle plate 10 of FIG. The needle hole guide 12 regulates the vertical movement of the sewing needle 13 to guarantee a constant needle drop point and to guarantee the formation of a needle thread loop formed in the Y direction (loop formation direction) shown in FIG. Is.
[0012]
As shown in FIG. 3, the boss portion 12a of the needle hole guide is formed with a notch 12b in a predetermined direction. It is preferable that this predetermined direction substantially coincides with the yarn guide locus (the S direction in the figure) by the capturing member (capturing means) 7.
[0013]
Further, the notch portion 12b of the needle hole guide boss portion is located within a predetermined angle range with respect to the needle thread loop forming direction Y. The predetermined angle range W is preferably 120 degrees and more preferably 90 degrees with respect to the axis X passing through the needle drop center point O and perpendicular to the loop forming direction. When the notch 12b is formed in the predetermined angle range W, the needle thread loop during sewing is reliably formed.
[0014]
Further, the width Q of the notch portion of the needle hole guide boss portion is set to a size capable of supporting the upper thread 30 and the lower thread 31 guided in the notch portion in parallel. This width Q needs to be changed according to the thickness of the upper and lower threads to be used. However, the thickness of the thread used is based on the thickness of the needle used. For this reason, it is necessary to change the needle hole guide as the thickness of the needle to be used is changed. In this case, the width Q of the notch portion of the needle hole guide is previously formed to a size corresponding to the thread to be used. Has been.
[0015]
Further, the notch upper end surface 12c of the needle hole guide boss portion is located in the vertical range P of the end surface of the upper insulating plate 6 in the vertical direction shown in FIG. For this reason, the upper and lower threads 30 and 31 captured by the capturing member 7 are guided to the heating element through the shortest path without being bent by the boss portion 12a of the needle hole guide. A wiper 14 is provided above the needle plate 10 to wipe the upper thread 30a on the sewing needle side after thread cutting.
[0016]
The capture member 7 of FIG. The capturing member 7 is rotatable with a predetermined amount of gap with respect to the needle plate 10. The catching member 7 is provided with a catching portion 7b for catching a yarn to be cut forward in the clockwise direction in the figure, while being provided with a yarn separating portion 7a for further separating the yarn not to be cut on the rear side. ing. The capture link 8 and the capture lever 9 constitute a link mechanism that transmits the movement of the connecting rod 11 to the capture member 7.
[0017]
The capture lever 9 is supported at the center so as to be rotatable about the connection pin 9b, is connected to the connection rod 11 at one end side so as to be rotatable about the rotation shaft 9a, and is connected to the capture link 8 at the other end side. It is connected to. The other end side of the capture link 8 is connected to the capture member 7 in a rotatable state. The connecting rod 11 is connected to a thread trimming drive mechanism that is driven at the time of thread trimming.
[0018]
The thread trimming drive mechanism has a solenoid 107 shown in FIG. The drive shaft 107a of the solenoid 107 is connected to one end of a lever 102 attached to a sewing machine frame (not shown) so as to be rotatable about a screw 149.
[0019]
A horizontal shaft 118 is attached to the sewing machine frame, and a link 165 is rotatably attached to the horizontal shaft 118 at one end thereof. A roller 138 is attached to the center of the link 165 by a bolt 139 and a nut 141, and the upper end of the vertical link 103 is connected to the other end via a nut 142 and a bolt 147. Further, an arm 166 is rotatably attached to the horizontal shaft 118. An abutting member 173 having a threaded portion at the tip is fixed to the arm 166 via a nut 175.
[0020]
The other end of the lever 102 is disposed at a position that can be engaged with the washers 122 and 123, and is configured to move the link 165 and the arm 166 to the left in the figure when the solenoid 107 is driven.
[0021]
The cam body 117 that rotates with an upper shaft (not shown) has a cam groove formed on the surface facing the roller 138. A contact body 167 having a stepped portion 167 a is fixed to the cam body 117 with a screw 176. The outer peripheral portion of the contact body 167 forms an arc shape, and the right outer peripheral portion 167b shown in the drawing protrudes from the outer periphery 117a of the cam body 117, and the left outer peripheral portion 167c is the outer periphery of the cam body 117. It is comprised so that it may not protrude from 117a.
[0022]
The contact member 173 attached to the arm 166 is urged in the direction of the center 117c of the cam body 117 by an elastic means (not shown), and the contact member 173 contacts the outer periphery 117a of the cam body 117 by a stopper (not shown). It is configured not to.
[0023]
One end of a link 125 is connected to the lower end of the vertical link 103 via a bolt 147 and a nut 142. A central portion of the link 125 is rotatably attached to the machine frame of the sewing machine by a bolt 150, and the connecting rod 11 is connected to the other end via a bolt 148 and a nut 143.
[0024]
The heating element 4 is a plate-like member made of, for example, stainless steel or nichrome, and connects the electrical cords 2 and 2 to both terminals 4b and 4c at the rear end, and the other from one terminal 4b through the tip 4a. It is formed in such a shape that current flows to the terminal 4c. And the front-end | tip part 4a makes a cross-sectional area small by making width | variety small, and the emitted-heat amount of the front-end | tip part 4a becomes large. For this reason, the calorific value required for yarn cutting can be obtained with low power. The electric cords 2 and 2 are connected to a transformer (not shown).
[0025]
As shown in FIG. 4, the heating element 4 is fixed to the needle plate by screws (not shown) while being sandwiched between the insulating plate 6 on the needle plate 10 side and the lower insulating plate 5. At this time, the front end portion 4a of the heating element has an arc shape along the needle hole guide boss portion, and can be attached close to the needle hole guide 12 fixed to the needle plate 10. Further, the tip 4a of the heating element can be provided close to the needle hole guide 12 even if it is linear.
[0026]
Further, the electric cords 2 and 2 are fixed to the needle plate 10 in a state where the electric cords 2 and 2 are connected to the heating element 4 by the cord attachment 3. Although a current flows through the heating element 4, as described above, since it is sandwiched and fixed between the insulating plates 5 and 6, safety is not impaired even if it is close to the vicinity of the needle hole.
[0027]
Further, the lower insulating plate 5 formed a notch 5 a along the yarn guide locus S of the upper and lower yarns 30 and 31 that are captured and moved by the capturing member 7. A gap is provided between the insulating member and the capturing member 7. This clearance reduces the resistance of the yarn when the upper and lower yarns 30 and 31 to be cut by the capturing member 7 are brought close to the heating element 4. Further, when the upper thread 30a on the sewing needle side is wiped by the wiper 14 after the thread is cut, no extra resistance is generated on the upper thread.
[0028]
The capturing member 7 is stopped at the standby position shown in FIG. 6 during sewing.
In the above configuration, when a thread trimming signal from the sewing pattern data is sent during sewing, the solenoid 107 is turned on and the thread trimming drive mechanism is driven. That is, in FIG. 5, the drive shaft 107a of the solenoid 107 is attracted, and the tip of the lever 102 rotates in the left direction (arrow A direction). Along with this, the link 165 and the arm 166 move to the left in the figure, and the roller 138 enters the cam groove of the cam body 117.
[0029]
The cam body 117 rotates with the rotation of the upper shaft (not shown), and the link 165 rotates around the horizontal shaft 118 via the roller 138 according to the shape of the cam groove and is connected to the other end of the link 165. 103 moves downward. As the vertical link 103 moves, the link 125 rotates and the connecting rod 11 moves to the left.
[0030]
When the outer peripheral portion 167 b of the contact body 167 moves to a position corresponding to the contact member 173 due to the rotation of the cam body 117, the outer peripheral portion 167 b of the contact body 167 contacts the contact member 173. Since the contact member 173 is biased in the direction of the contact body 167 by elastic means (not shown), a frictional force is generated between the contact member 173 and the contact body 167. Due to this frictional force, the link 165 is sandwiched between the arm 166 and the cam body 117 so that the roller 138 does not separate from the cam groove of the cam body 117.
[0031]
Thus, by driving the thread trimming drive mechanism, the connecting rod 11 is pushed and moves upward in FIG. 1, and the movement is transmitted via the catch lever 9 and the catch link 8, so that the catch member 7 is shown in FIG. It rotates in the clockwise direction R1. This counterclockwise rotation further divides the yarn (the needle-side upper thread 30a) that the yarn separating portion 7a of the catching member 7 does not cut, and further the remaining upper and lower yarns (cloth-side on the fabric side) to be cut in the catching portion 7b. The upper thread 30b and the lower thread 31) are captured. The capture member 7 moves to the forward movement position in the opposite direction across the needle hole 12d with respect to the standby position shown in FIG. 6 by the rotation in the counterclockwise direction R1.
[0032]
As the cam body 117 continues to rotate, the link 165, the upper and lower links 103, and the link 125 move in the opposite direction according to the shape of the cam groove, and the connecting rod 11 is pulled. The capture member 7 rotates in the clockwise direction R2. As shown in FIG. 4, the upper and lower threads 30 and 31 to be cut are guided by the notch 12 b of the needle hole guide 12 by the clockwise rotation of the capturing member 7, and then contact the tip 4 a of the heating element 4. However, it is guided into the notch 5a of the lower insulating plate 5. Next, the rotation of the spindle is stopped and the solenoid 107 is turned off. In the case of the conventional thread trimming device, as described above, when the rotation angle of the main shaft reaches around 50 degrees, the rotation of the main shaft is stopped, and the catching member is moved to the yarn cutting / standby position shown in FIG. . On the other hand, in the case of the present embodiment, the rotation is stopped when the rotation angle of the main shaft is close to 40 degrees on the top dead center side than before. As a result, as shown in FIGS. 1, 2, and 4, the capture member 7 stops at an intermediate position located at the end of the needle hole on the standby position side. At this intermediate position, the capturing member 7 is in a position that hides the distal end portion 4a of the heating element 4. Since the solenoid 107 is turned off, the tip of the lever 102 rotates to the right in FIG. 5, but the roller 138 is connected to the cam body 117 due to the frictional force between the contact member 173 and the contact body 167. The cam groove is maintained.
[0033]
After the capture member 7 stops at this intermediate position, a heating signal is sent to the transformer, a current is passed through the heating element 4 via the electric cords 2 and 2, and the tip 4a of the heating element 4 is heated. When a predetermined time elapses, the upper thread 30b and the lower thread 31 on the cloth side that are in contact with the tip 4a of the heating element 4 are cut at a predetermined cutting position. On the other hand, since the upper thread 30a on the sewing needle 13 side is not in contact with the thread fusing part 4a of the heating element 4, it remains uncut. This is because the capturing member 7 is closer to the tip portion 4a of the heating element 4 than in the case of FIG. The upper thread 30a on the sewing needle side after thread cutting is wiped by the wiper 14.
[0034]
Thus, in the present invention, when the current flows through the heating element 4, the capturing member 7 is stopped at the intermediate position so that the needle-side upper thread 30 a does not contact the heating element 4. The needle-side upper thread 30a is not melted.
[0035]
When the sewing machine main shaft rotates at the start of the next sewing, the capture member 7 further rotates clockwise R2 by the rotation of the cam body 117. When the outer peripheral portion 167 c of the contact body 167 moves to a position corresponding to the contact member 173, the contact between the contact body 167 and the contact member 173 is released. As a result, the roller 138 is detached from the cam groove of the cam body 117. In this way, when the sewing needle enters the hole 12d of the needle hole guide 12 as shown in FIG. 6, the capturing member 7 stops at a position where the sewing needle and the capturing member 7 are prevented from interfering with each other.
[0036]
As mentioned above, although this invention was demonstrated based on embodiment shown in drawing, this invention is not limited to this embodiment, but can be variously deformed.
[0037]
【The invention's effect】
According to the present invention, a sewing needle that moves up and down in conjunction with the sewing machine main shaft, a needle plate for supporting the workpiece by reciprocating movement beneath the needle plate, the upper thread of the workpiece side to be cut A catching means for catching the upper thread and the lower thread on the side connected to the sewing product on one side surface in the reciprocating direction , and capturing the upper thread on the side connected to the needle on the other side surface, A needle hole is formed by being fixed to the needle plate, and a boss portion projecting downward from a lower end edge of the needle hole, and a lower end of the boss portion along a yarn guiding direction of the catching means A needle hole guide having a formed notch, and fixed to the lower surface of the needle plate so that a tip portion is disposed on the thread guide direction side of the needle hole and in the vicinity of the needle hole guide; A heating element that generates heat by flowing the upper and lower threads captured by the capturing means. In a thread trimming device for a sewing machine that is melted by being brought into contact with the tip of a body, the capture means includes a standby position, a forward movement position in the opposite direction across the needle hole with respect to the standby position, and the one side surface. A position that is located on the yarn guide direction side of the tip of the heating element, and that the tip of the heating element is positioned between the one side surface and the other side surface in the yarn guide direction. A moving means for stopping movement to an intermediate position that hides the tip of the heating element and stopping the capturing means at the intermediate position when a current is passed through the heating element, Sewing machine thread configured such that the upper thread connected to the workpiece is brought into contact with the tip of the heating element and the upper thread connected to the raised needle is not in contact with the tip of the heating element. A cutting device is provided. Accordingly, the upper thread on the needle side is not melted and the upper thread remains on the needle side, so that a stable seam can be formed at the start of the next sewing.
[Brief description of the drawings]
FIG. 1 is a bottom view of a thread trimming device for a sewing machine according to an embodiment of the present invention as viewed from below a needle plate.
2 is an enlarged view of the vicinity of a needle hole guide in FIG.
FIG. 3 is an explanatory diagram of a formation position of a notch portion of the needle hole guide of FIG. 1;
4 is a cross-sectional view in the ZZ direction of FIG. 1;
5 is an exploded perspective view showing a thread trimming drive mechanism of the apparatus of FIG. 1. FIG.
6 is a bottom view showing a state in which the capturing member of the apparatus of FIG. 1 is in a standby position. FIG.
FIG. 7 shows an example of a thermal fusing type thread trimming apparatus.
8 is a cross-sectional view in the ZZ direction of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 4 Heating element 4a Tip part 5,6 Insulating plate 5a Notch part 7 Capture member (capturing means) 7a Thread separation part 7b Capture part 10 Needle plate 12 Needle hole guide 12a Boss part 12d Hole part 13 Sewing needle 14 Wiper 30 Upper thread 30a Needle Upper thread 30b on the fabric side Upper thread 31 Lower thread 66 Needle position 102 Lever 103 Vertical link 107 Solenoid 107a Drive shaft 117 Cam body 117a Outer periphery 117c Center 118 Horizontal shaft 125 Link 138 Roller 165 Link 166 Arm 167 Contact body 167a Step Part 167b outer peripheral part 167c outer peripheral part 173 contact member

Claims (1)

A sewing needle that moves up and down in conjunction with the sewing machine spindle,
A throat plate for supporting the workpiece,
By reciprocate below the needle plate, of the yarn and the lower yarn on the workpiece side to be cut, the yarn with one aspect of the lower thread the reciprocating direction on a side connecting to the workpiece Capturing means that captures the upper thread on the side connected to the needle on the other side;
A needle hole is formed by being fixed to the needle plate, and a boss portion projecting downward from a lower end edge of the needle hole, and a lower end of the boss portion along a yarn guiding direction of the catching means A needle hole guide having a notch formed;
A heating element that is fixed to the lower surface of the throat plate so that a tip portion is disposed in the thread guide direction side of the needle hole and in the vicinity of the needle hole guide, and that generates heat by passing an electric current. ,
In a thread trimming device for a sewing machine, in which the upper and lower threads captured by the capturing means are brought into contact with the tip of the heating element and melted,
The capture means includes a standby position, a forward movement position in the opposite direction across the needle hole with respect to the standby position, and a position where the one side surface is located on the yarn guide direction side of the tip of the heating element. An intermediate position where the leading end of the heating element is positioned between the one side surface and the other side surface in the yarn guiding direction so as to hide the leading end portion of the heating element. Make a moving means to stop moving,
When an electric current is passed through the heating element, the catching means is stopped at the intermediate position, and the upper thread connected to the sewing object is brought into contact with the tip of the heating element by the catching means and is raised. A thread trimming device for a sewing machine, characterized in that the upper thread connected to the needle does not contact the tip of the heating element.

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