JP2009095501A - Thread cutter of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thread cutter of a sewing machine capable of securely cutting a looper thread. <P>SOLUTION: After sewing is completed, a movable knife 30 moves to an advance position for holding needle threads T2 and T3 and the looper thread T1, and retreats to a retreat position so as to cut the needle threads T2 and T3 and the looper thread T1 in conjunction with a fixed knife 31 provided in the retreat position. A thread branching guide part 32 is formed on a tip part 25 of the movable knife 30 so as to project downstream in an advance direction A1 in order to securely guide the looper thread T1 to a looper thread holding part 26. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a needle thread that is stretched between a needle plate and a looper and a thread cutting device for a sewing machine that captures and cuts the looper thread, and more particularly to a structure of a movable knife provided in the thread cutting device.

  FIG. 13 is a partial perspective view showing a thread cutting device 1 for a conventional sewing machine. A conventional thread trimming device 1 for a sewing machine is described in Patent Document 1, for example. In this prior art, the looper thread T1 and the needle threads T2 and T3 connected to the end of the seam formed on the workpiece are stretched from the needle drop hole of the needle plate over the looper 2 to form a series of stitches. Then, the movable knife 3 moves forward in the direction of the arrow A1, and the tension portion T1a of the looper thread T1 stretched over the looper 2 from the needle drop hole and the tension portions T2a of the needle threads T2, T3, T2b; after capturing T3a and T3b, retract in the direction of the arrow A2 and draw to the cutting edge 4a of the fixed knife 4 provided at the retracted position, and the cutting blade formed on the cutting edge 4a of the fixed knife 4 In cooperation with 4b, each tension portion T1a; T2a, T2b; T3a, T3b of each needle thread T1, T2, T3 is cut.

  The movable knife 3 is a plate-like longitudinal member having an upper surface and a lower surface arranged in parallel with a virtual plane substantially perpendicular to the movement path of the sewing needles 5 and 6 reciprocated up and down, and the upper surface is a needle plate. The lower surface faces the looper 2. A tapered tip end portion 7 is formed at one end of the movable knife 3 on the downstream side in the advance direction A1 toward the downstream side in the advance direction A1, and on the upstream side in the feed direction B of the sewing product from the tip portion 7. In the vicinity, a looper thread engaging recess 8 and a needle thread engaging recess 9 are formed.

  When the movable knife 3 moves forward after the sewing operation is stopped, the distal end portion 7 of the movable knife 3 enters between the stretched portions T3a and T3b of one needle thread T3 arranged on the most retracted position side. Further, the stretched portion T1a of the looper thread T1 passes through the upstream side B in the feed direction B of the sewing product from the stretched portion T1a of the looper thread T1, that is, the front side perpendicular to the paper surface of FIG. The guide surface 10 connected to the downstream side in the feed direction B of the sewing product is guided and captured by the looper thread engaging recess 8 and the stretched portions T2a and T3a of the needle threads T2 and T3 are The needle thread engaging recess 9 guides and catches it, and as described above, the retracting operation of the movable knife 3 in the direction of the arrow A2 causes each stretched portion T1a of all the threads T1, T2, T3 connected to the sewing product. , T2a, T2b; T3a, 3b draws to the retracted position, cutting in cooperation with the fixed knife 4.

Japanese Utility Model Publication No. 63-10149

  In the prior art, as described above, the movable knife 3 moves forward in the direction of the arrow A1 to capture the stretched portion T1a of the looper thread T1, and then moves backward in the direction of the arrow A2 to stretch the looper thread T1. When the portion T1a is cut together with the stretched portions T2a, T2b; T3a, T3b of the needle yarns T2, T3, the stretched portion T1a of the looper yarn T1 is wound around the looper 3 in a substantially U shape. The needle thread T2 can pass through the tension parts T2a and T2b and between the tension parts T3a and T3b almost certainly, but the tension part T1a of the looper thread T1 moves the movable knife 3 forward in the direction of the arrow A1. The looper thread T1 is guided and captured in the looper thread engaging recess 8 when it is in a state of being moved to the upstream side in the feed direction B of the workpiece from the movement path of the tip portion 7 due to vibration and other factors. There is a situation where you can't It is impossible to cut the looper thread T1 wants.

  An object of the present invention is to provide a thread trimming device for a sewing machine capable of reliably cutting a looper yarn.

The present invention has a yarn catching portion for catching a needle thread and a looper yarn at the tip, and a forward position where the thread catching portion enters between the needle plate and the looper, and a retracted position retracted from the forward position. A movable knife that reciprocates between
In cooperation with the movable knife, the needle thread and looper thread captured by the thread catching portion of the movable knife are retracted from the stretch position during sewing by moving the movable knife from the forward position to the backward position. In a thread trimming device for a sewing machine including a fixed knife for cutting,
A thread trimming device for a sewing machine, wherein the movable knife is formed with a yarn dividing guide portion for guiding a looper yarn to the yarn catching portion in a region closer to the tip than the yarn catching portion.

  According to the present invention, the movable knife is stretched between the needle plate of the looper thread and the looper when the movable knife moves in the forward direction by the yarn dividing guide portion formed on the tip side of the yarn catching portion of the movable knife. The tension part is guided to the thread catcher side, the looper thread is securely caught by the thread catch part, and the movable knife moves to the retracted position, so that the tension part of the captured looper thread cooperates with the fixed knife. And can be cut reliably.

  Further, according to the present invention, the yarn dividing guide portion is located on the tip of the movable knife at a position opposite to the side on which the yarn catching portion is formed with respect to a virtual plane including the axis of the movable knife, and from the retracted position to the advanced position. It is characterized in that it is formed so as to protrude downstream in the forward traveling direction.

  According to the present invention, the yarn dividing guide portion is formed at the distal end portion of the movable knife so as to protrude downstream in the forward direction from the retracted position to the advanced position, so that the looped portion of the looper yarn can be used for vibration of the looper and others. Due to the above factors, even when moving to the opposite side of the yarn catching portion with respect to the virtual plane including the axis from the tip of the movable knife, the stretched portion is guided to the yarn catching portion side with respect to the virtual plane, The looper yarn can be surely captured and cut.

  Further, according to the present invention, the thread dividing guide portion is formed on the distal end portion of the movable knife from the upper surface facing the needle plate of the movable knife on the side where the thread catching portion is formed with respect to a virtual plane including the axis of the movable knife. It is also characterized by being formed in a concave shape.

  According to the present invention, since the yarn dividing guide portion is formed at the distal end portion of the movable knife on the side where the yarn catching portion is formed with respect to the virtual plane, it is recessed from the upper surface. Is guided from the tip of the movable knife toward the yarn catching portion by the yarn dividing guide portion, and the looper yarn can be reliably caught and cut.

  Further, according to the present invention, the thread dividing guide portion is located on a side opposite to the side where the yarn catching portion is formed with respect to a virtual plane including the axis of the movable knife at the tip of the movable knife. It is formed to protrude from the upper surface facing the surface.

  According to the present invention, the yarn dividing guide portion is formed on the opposite side to the side on which the yarn catching portion is formed with respect to the virtual plane, and is formed so as to protrude from the upper surface. Can also be prevented from moving to the opposite side of the yarn catching portion with respect to the virtual plane, and can be guided to the yarn catching portion side by the yarn dividing guide portion, whereby the stretched portion of the looper yarn can be It is possible to guide the yarn catcher side and securely catch the looper yarn and cut it.

  According to the present invention, since the yarn dividing guide portion is formed at the distal end portion of the movable knife so as to protrude downstream in the forward direction from the retracted position to the forward position, the looped portion of the looper yarn can be used for vibration of the looper and other Due to the factor, it is possible to prevent the moving knife from moving to the opposite side of the thread catcher with respect to the virtual plane including the axis from the tip of the movable knife, and guide the stretched part to the thread catcher with respect to the virtual plane. Thus, the looper yarn can be reliably captured and cut.

  According to the present invention, since the yarn dividing guide portion is formed so as to protrude downstream in the forward direction, the tension portion of the looper yarn includes the axis line more than the tip of the movable knife due to the vibration of the looper and other factors. It is possible to prevent movement to the opposite side to the yarn catching portion with respect to one plane, guide the stretched portion to the yarn catching portion side with respect to the virtual one plane, and reliably catch and cut the looper yarn. it can.

  According to the present invention, since the yarn dividing guide portion is formed to be recessed from the upper surface of the movable knife, the stretched portion of the looper yarn includes the axis line more than the tip of the movable knife due to the vibration of the looper and other factors. Preventing the virtual one plane from moving to the opposite side of the yarn catching portion, guiding the stretched portion to the yarn catching portion side with respect to the virtual one plane, and reliably catching and cutting the looper yarn. Can do.

  According to the present invention, since the yarn dividing guide portion is formed to be recessed from the upper surface of the movable knife, the tension portion of the looper yarn includes the axis line more than the tip of the movable knife due to the vibration of the looper and other factors. It is possible to prevent movement to the opposite side to the yarn catching portion with respect to one plane, guide the stretched portion to the yarn catching portion side with respect to the virtual one plane, and reliably catch and cut the looper yarn. it can.

  FIG. 1 is a partial perspective view showing a thread trimming device 20 for a sewing machine according to an embodiment of the present invention. The thread trimming device 20 of the sewing machine according to the present embodiment is provided under the sewing machine bed of the double chain stitch sewing machine or the flat stitch sewing machine, and the needle drop of the needle plate 21 of the looper thread T1 and the needle threads T2 and T3 when the sewing operation is stopped. Of the stretched portions T1a; T2a, T2b; T3a, T3b extending between the holes 22, 23 and the looper 28, the stretched portions T1a connected to the workpiece are looped by the looper thread catching portion 26, and the needles T2a, T3a are stitched. The yarn catching section 27 is configured so that it can be cut at the retracted position where it is captured and retracted from the needle drop position.

  The thread trimming device 20 has a looper thread T1 and a needle thread capturing section 26 and a needle thread capturing section 27 for capturing the looper thread T1 and the respective needle threads T2 and T3 at the tip end section 25. These thread capturing sections 26 and 27 are needle plates. A movable knife 30 that reciprocates in the directions of arrows A1 and A2 between a forward position that has entered between 21 and the looper 28 and a backward position that has been retracted from the forward position, and a thread catcher 26 of the movable knife 30; The looper thread T1 and the needle threads T2, T3 captured by the belt 27 are retracted from the stretch position at the time of sewing by moving the movable knife 30 in the direction of the arrow A2 from the advance position to the retract position. A fixed knife 31 that cuts in cooperation with the knife 30 is included.

  In the movable knife 30 provided in such a thread trimming device 20, a looper thread T1 is provided on the tip side of the looper thread catching portion 26, that is, in a region on the downstream side in the arrow A1 direction (left side in FIG. 1). A yarn dividing guide portion 32 for guiding the yarn to the looper yarn catching portion 26 is formed.

  FIG. 2 is an enlarged plan view showing the vicinity of the tip 34 of the movable knife 30, and FIG. 3 is a plan view showing the entire movable knife 30. The thread dividing guide portion 32 includes a central axis L1 of the movable knife 30 at the distal end portion 34 of the movable knife 30, and is a virtual one plane perpendicular to the upper surface or the lower surface of the movable knife 30 (that is, perpendicular to the paper surface of FIG. 2). With respect to the side where the looper yarn catching portion 26 is formed (ie, the lower side in FIG. 2), the position is eccentric by a distance ΔL, and protrudes downstream in the forward direction A1 from the reverse position toward the forward position. It is formed.

  The fixed knife 31 fixed to the machine body of the sewing machine is laminated on the movable knife 30, and a drive lever (not shown) is connected to the base end portion 35 protruding from the fixed knife 31 in the backward direction A2. The movable knife 30 is displaced and driven in the forward direction A1 and the backward direction A2 by the lever. The free end of the thread presser spring 36 abuts elastically on the lower surface of the movable knife 30, and the base end of the thread presser spring 36 is fixed to a fixed knife mount (not shown). By such a thread presser spring 36, the start end portion of the next stitch of the looper thread T1 cut by the movable knife 30 and the fixed knife 31 is held.

  4 is an enlarged perspective view of the vicinity of the distal end portion 34 of the movable knife 30, and FIG. 5 is a rear view showing a state in which the looper yarn T1 is being guided to the looper yarn catching portion 26 side by the yarn dividing guide portion 32. As described above, since the yarn dividing guide portion 32 is formed on the tip side of the looper yarn catching portion 26 of the movable knife 30, when the movable knife 30 is moved in the forward movement direction A1 by the yarn dividing guide portion 32, The stretched portion T1a stretched between the needle plate 21 and the looper 28 of the looper yarn T1 is guided to the looper yarn catching portion 26 side, and the looper yarn T1 can be reliably caught by the looper yarn catching portion 26. it can. Therefore, when the movable knife 30 moves in the direction of the arrow A2 and is displaced to the retracted position, the stretched portion T1a of the looper thread T1 captured by the looper thread capturing section 26 is reliably cut in cooperation with the fixed knife 31. Can do.

  6 to 8 are views for explaining the operation of the thread trimming device 20. FIG. 6 (1) shows a state in which the looper 28 has moved to the forward movement position and has captured the needle threads T2 and T3. (2) shows a state immediately after the movable knife 30 moves to the forward movement position and guides the looper yarn T1 to the looper yarn catching section 26 side. FIG. 7A shows a state where the looper thread T1 is captured by the looper thread trapping portion 26 of the movable knife 30 moved to the forward movement position, and FIG. 7B shows that the movable knife 30 moves in the backward direction A2. A state immediately before cutting in which the looper thread T1 is drawn into the retracted position together with the respective needle threads T2, T3 is shown. Further, FIG. 8 (1) shows a state in which the looper thread T1 and the needle threads T2 and T3 are cut, and FIG. 8 (2) shows the T2b and T3b of the needle threads T2 and T3 after being cut on the sewing product. Shown in the raised state.

  When a series of stitches are formed, the reciprocating back and forth movement of the looper 28 along the directions of arrows A1 and A2 is stopped, and the movable knife 30 is retracted under the fixed knife 31 as shown in FIG. It moves in the forward direction A1 from the position and passes between the substantially U-shaped stretched portions T2a and T2b and between the stretched portions T3a and T3b of the needle threads T2 and T3 captured by the looper 28. 6 (2), even if the stretched portion T1a of the looper thread T1 is slightly displaced to the upstream side in the feed direction B with respect to the central axis L1 of the movable knife 30 (front side in FIG. 6 (2)). Then, the yarn dividing guide portion 32 turns around to the upstream side in the feeding direction B from the stretched portion T1a and is reliably guided to the looper yarn catching portion 26 side. As shown in FIG. T1a fits into the looper yarn catching portion 26 and is reliably caught.

  As shown in FIG. 7 (2), the tension portion T1a of the looper thread T1 captured in this way is drawn to the retracted position side together with the needle threads T2 and T3 when the movable knife 30 moves in the backward direction A2. As shown in FIG. 8A, after the needle threads T2 and T3 are cut, the looper thread T1 is cut, and the start portion of the next stitch of the looper thread T1 is moved by the thread presser spring 36. The needle thread T2b, T3b is pulled up onto the sewing product as shown in FIG.

  As described above, since the yarn dividing guide portion 32 is formed at the front end portion of the movable knife 30 so as to protrude downstream in the forward direction A1, the looper yarn T1 can be reliably captured and cut.

  FIG. 9 is a perspective view showing a part of a movable knife 30a used in a thread trimmer according to another embodiment of the present invention. FIG. 10 shows the looper thread T1 on the side of the looper thread catching section 26 by the thread dividing guide section 32. It is a rear view for demonstrating the state guided by. Note that portions corresponding to those of the above-described embodiment are denoted by the same reference numerals. In the thread trimming device according to the present embodiment, the yarn dividing guide portion 32 is provided on the side where the looper yarn catching portion 26 is formed at the distal end portion of the movable knife 30a with respect to a virtual plane including the axis L1 of the movable knife 30a. The upper end of the movable knife 30a facing the needle plate 21 is recessed.

  Thus, since the yarn dividing guide portion 32 is formed to be recessed from the upper surface of the movable knife 30a on the side where the looper yarn catching portion 26 is formed with respect to the virtual plane, the stretched portion T1a of the looper yarn T1 is formed. Due to the vibration of the looper and other factors, it is possible to prevent the imaginary plane including the axis from moving toward the opposite side to the yarn catching portion with respect to the imaginary plane including the axis. Can be guided to the yarn catching portion 26 side, and the looper yarn can be reliably caught and cut.

  FIG. 11 is a perspective view showing a part of a movable knife 30b used in a thread trimming apparatus according to still another embodiment of the present invention. FIG. 12 shows the looper thread T1 guided to the yarn dividing guide portion 32 of the movable knife 30b. It is a rear view for demonstrating the operation | movement performed. Note that portions corresponding to those of the above-described embodiment are denoted by the same reference numerals. In the thread trimming device of the present embodiment, the yarn dividing guide portion 32 is on the opposite side to the side where the looper yarn catching portion 26 is formed on the virtual flat plane including the axis of the movable knife 30b at the tip of the movable knife 30b. Thus, it is formed so as to protrude from the upper surface facing the needle plate 21 of the movable knife 30b.

  In this way, since the yarn dividing guide portion is formed on the opposite side to the side on which the looper yarn catching portion is formed with respect to the virtual plane, the stretched portion T1a of the looper T1 has the vibration of the looper. Due to other factors, it is prevented from moving to the opposite side of the thread catcher with respect to the virtual plane including the axis from the tip of the movable knife, and the tension portion T1a is moved to the thread catcher with respect to the virtual plane. It can guide to 26 side, can catch a looper thread | yarn reliably, and can cut | disconnect.

  In still another embodiment of the present invention, the first thread dividing guide portion 32 protruding in the forward direction A1 shown in FIGS. 1 to 8 and the upper surface shown in FIGS. Both the second thread dividing guide part 32 that is also recessed may be formed, and the first thread dividing guide part 32 protruding in the forward direction A1 shown in FIGS. 1 to 8 and FIGS. Both the third yarn dividing guide portion 32 raised from the upper surface shown in FIG. 9 and the second yarn dividing guide portion 32 recessed from the upper surface shown in FIG. 9 and FIG. Both the third yarn dividing guide portion 32 protruding from the upper surface shown in FIG. 12 may be formed, and further, the first yarn dividing guide portion 32 protruding in the advancing direction A1 shown in FIG. 1 to FIG. 9 and FIG. 10, the second thread dividing guide portion 32 recessed from the upper surface, and FIG. All the third yarn dividing guide portion 32 that protrudes from the upper surface shown in and Figure 12 may be formed. By appropriately combining these first to third yarn dividing guide portions and forming them at the tip of the movable knife, it is possible to more reliably prevent looper yarn catching mistakes.

1 is a partial perspective view showing a thread trimming device 20 for a sewing machine according to an embodiment of the present invention. FIG. 3 is an enlarged plan view showing the vicinity of a distal end portion 34 of a movable knife 30. 3 is a plan view showing the entire movable knife 30. FIG. 3 is an enlarged perspective view of the vicinity of a distal end portion 34 of the movable knife 30. FIG. 7 is a rear view showing a state where the looper yarn T1 is being guided to the looper yarn catching portion 26 side by the yarn dividing guide portion 32. FIG. FIGS. 6A and 6B are diagrams for explaining the operation of the thread trimming device 20, in which FIG. 6A shows a state in which the looper 28 has moved to the forward movement position to capture the needle threads T1 and T2, and FIG. The state immediately after 30 moves to the advance position and guides the looper yarn T1 to the looper yarn catching portion 26 side is shown. FIG. 7A is a view for explaining the operation of the thread trimming device 20. FIG. 7A shows a state in which the looper thread T1 is captured by the looper thread capturing section 26 of the movable knife 30 moved to the forward movement position. 2) shows a state immediately before cutting in which the movable knife 30 moves in the backward direction A2 and pulls the looper thread T1 into the retracted position together with the needle threads T2 and T3. FIGS. 8A and 8B are diagrams for explaining the operation of the thread trimming device 20, FIG. 8A shows a state in which the looper thread T1 and the needle threads T2 and T3 are cut, and FIG. A state in which the threads T2 and T3 are pulled up on the workpiece is shown. It is a perspective view which shows a part of movable knife 30a used for the thread trimming device of the sewing machine of the other form of implementation of this invention. 7 is a rear view for explaining a state in which the looper yarn T1 is guided to the looper yarn catching portion 26 side by the yarn dividing guide portion 32. FIG. It is a perspective view which shows a part of movable knife 30b used for the thread trimming device of the sewing machine of the further another form of implementation of this invention. It is a rear view for demonstrating the operation | movement by which the looper thread | yarn T1 is guided to the thread | yarn division guide part 32 of the movable knife 30b. It is a partial perspective view which shows the thread trimming device 1 of the prior art sewing machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Thread trimming device 21 Needle plate 22, 23 Needle drop hole 25 Tip part 26 Looper thread catching part 27 Needle thread catching part 28 Looper 30, 30a, 30b Movable knife 31 Fixed knife 32 Thread separation guide part 34 Tip part of movable knife 30 L1 Center axis of movable knife 30 T1 Looper thread T2, T3 Needle thread T1a; T2a, T2b; T3a, T3b

Claims (4)

There is a thread catching part that catches the needle thread and looper thread at the tip, and the thread catching part reciprocates between the advance position where it entered between the needle plate and the looper and the retracted position retracted from this advance position. A movable scalpel that moves,
In cooperation with the movable knife, the needle thread and looper thread captured by the thread catching portion of the movable knife are retracted from the stretch position during sewing by moving the movable knife from the forward position to the backward position. In a thread trimming device for a sewing machine including a fixed knife for cutting,
A thread trimming device for a sewing machine, wherein the movable knife is formed with a yarn dividing guide portion for guiding a looper yarn to the yarn catching portion in a region closer to the tip than the yarn catching portion.   The thread dividing guide portion is on the opposite side of the tip of the movable knife from the side where the yarn catching portion is formed with respect to a virtual plane including the axis of the movable knife, and downstream in the forward direction from the retracted position to the advanced position. The thread trimming device for a sewing machine according to claim 1, wherein the thread trimming device is formed so as to project from the sewing machine.   The thread dividing guide portion is formed at the distal end portion of the movable knife at a side where the thread catching portion is formed with respect to a virtual plane including the axis of the movable knife, and is recessed from the upper surface facing the needle plate of the movable knife. The thread trimming device for a sewing machine according to claim 1, wherein:   The thread dividing guide portion is raised from the upper surface facing the needle plate of the movable knife on the opposite side of the tip of the movable knife from the side on which the yarn catching section is formed with respect to a virtual plane including the axis of the movable knife. The sewing machine thread trimming apparatus according to claim 1, wherein the sewing machine thread trimming apparatus is formed as described above.

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