sewing machine

Abstract

We provide a sewing machine that allows for flexible adjustment of the thread cutting position. [Solution] The invention provides a needle 2, a needle plate 3 that supports the fabric from below and has a needle drop 31 through which the vertically moving needle 2 passes, a looper 4 located below the needle plate 3 that holds the looper thread and moves back and forth to entangle the looper thread with the needle thread, and a female part 55 that moves between the needle plate 3 and the looper 4 to cut the needle thread and the looper thread that are connected to the fabric after sewing. The female part 55 is capable of changing the cutting position relative to the needle plate 3, and a space is provided between the needle plate 3 and the looper 4 in which the female part 55 can be positioned in the changed position, in the posture before cutting.

Description

Technical Field

[0001] The present invention relates to a sewing machine provided with a thread cutting mechanism.

Background Art

[0002] Conventionally, as a sewing machine provided with a thread cutting mechanism, there is, for example, the sewing machine described in Patent Document 1. In Patent Document 1, an upper blade and a lower blade for cutting a thread (a needle thread and a looper thread) standby laterally with respect to the looper during a sewing operation, and later the combination of the upper blade and the lower blade advances up to substantially directly above the looper, where only the lower blade is further moved leftward to catch the thread and then returned rightward, and the upper blade is engaged therewith to cut the thread, and thereafter the combination of the upper blade and the lower blade is returned to the standby position. A thread cutting method for a double-loop sewing machine and an apparatus for implementing the method are described.

[0003] However, in the sewing machine described in Patent Document 1, the thread is cut at a position that is separated to the right from the needle drop of the needle plate, with respect to the operator's standard, by hooking with the lower blade and moving it rightward. In this configuration, since the thread has to be cut at a position separated from the needle drop, the thread remaining on the fabric becomes longer by the separated amount. Therefore, when the thread cut by the sewing machine is longer than the desired length, the operator may need to perform further processing such as cutting the thread manually later to tidy up the appearance, which has been time-consuming.

[0004] And in the configuration described in Patent Document 1, even if the cutting position is attempted to be moved leftward with respect to the operator's standard, as shown in FIG. 3 of Patent Document 1, there is thickness around the portion where the cutting is performed, and it interferes with the looper, so it was physically impossible.

[0005] Furthermore, there was also a demand from sewing machine users to set the length of the thread remaining on the fabric to a desired length, such as making it longer rather than shorter, from the viewpoints of preventing fraying and preventing the operator from accidentally damaging the fabric during the operation of tidying up the appearance. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 61-276597 (Figure 3) [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, in view of the above problems, the present invention aims to provide a sewing machine that can freely adjust the thread cutting position. [Means for solving the problem]

[0008] The present invention relates to a sewing machine comprising: a needle that moves up and down to penetrate the fabric to be sewn while holding the needle thread; a needle plate that supports the fabric from below and has a needle drop through which the moving needle passes; a looper that moves back and forth below the needle plate to hold the looper thread and entangle the looper thread with the needle thread; and a cutting part that moves between the needle plate and the looper and cuts the needle thread and the looper thread that are connected to the fabric after sewing, wherein the cutting position of the cutting part that cuts the needle thread and the looper thread can be changed relative to the needle plate, and a space is secured between the needle plate and the looper in which the cutting part can be positioned in the position before cutting in the changed position.

[0009] Furthermore, the female part may include a fixed female part that is immovable, and a movable female part that is rotatably mounted relative to the fixed female part so as to perform a scissor-like motion in combination with the fixed female part.

[0010] Furthermore, the position change can be made by adjusting the position of the fixed blade relative to the needle plate in the fabric feeding direction at the time of cutting the needle thread and the looper thread.

[0011] Furthermore, the female part is in a standby state away from the needle drop during sewing, and after sewing is completed, it moves into an advanced state below the needle drop and above the looper, and from that state a cutting operation is performed to cut the needle thread and the looper thread, after which it returns to the standby state.

[0012] Furthermore, the degree of opening of the fixed and movable scalpels when they are open can be adjusted. [Effects of the Invention]

[0013] In this invention, a space is provided between the needle plate and the looper that allows the cutting section, in its repositioned state before cutting, to be positioned. Therefore, unlike conventional methods, it is not necessary to cut at a position far from where the needle falls, and the cutting position can be changed to a desired location on the fabric after sewing to cut the needle thread and looper thread. Thus, the thread cutting position can be freely adjusted. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view showing a sewing machine according to one embodiment of the present invention, illustrating the case where the cutting blade is in a standby state. [Figure 2] This is a perspective view showing the case where the female part is in the extended position (before thread cutting). [Figure 3] This is a perspective view showing the point in time when the female part moves further from its advanced position to cut the thread. [Figure 4] This is a schematic perspective view showing the relationship between the cutting edge and the threads (needle thread and looper thread) in the aforementioned sewing machine, where (a) shows the state just before the threads are cut, (b) shows the state after one of the three needle threads and the looper thread have been cut, and (c) shows the state after all the threads have been cut. [Figure 5] This is a longitudinal cross-sectional view of the area around the tip (blade edge) of the female part of the sewing machine, viewed from the base end to the tip end, showing the vertical relationship between the fixed and movable blades of the female part and the looper. [Modes for carrying out the invention]

[0015] Next, we will describe one embodiment of the present invention. Regarding the front-to-back direction, the side closer to the sewing worker is referred to as the "front side," and the side further away is referred to as the "back side." That is, in this embodiment of the sewing machine, the worker is positioned on the front side as indicated in Figures 1 to 3. Furthermore, the up, down, left, and right directions are expressed as those seen from the worker's perspective of the sewing machine. "Horizontal direction" refers to the left-right direction from the worker's perspective. "Directly below" and "directly above" refer to the vertical direction of up and down.

[0016] -Overview of the sewing machine- The sewing machine 1 of this embodiment can, for example, perform double chain stitch sewing. However, it is not limited to this, and the present invention is applicable to all sewing machines that can perform sewing with needle thread Y1 and looper thread Y2 (see Figure 4(a)). Figures 1 to 3 are perspective views of the sewing machine 1 of this embodiment, showing the main parts related to thread cutting rather than the whole machine. For explanatory purposes, the illustrated state is with the cover removed and a part of the internal structure of the sewing machine exposed.

[0017] The sewing machine 1 of this embodiment includes a needle 2 that moves up and down to penetrate the fabric to be sewn (not shown) while holding the needle thread Y1 (see Figures 4(a) to (c)), a needle plate 3 that supports the fabric from below and has a needle drop 31 which is a through hole through which the up and down moving needle 2 passes, and a looper 4 located below the needle plate 3 that moves back and forth along a horizontal path perpendicular to the fabric feeding direction to entangle the looper thread Y2 with the needle thread Y1 in order to form a double chain stitch on the fabric. The configurations of these parts can be those of known sewing machines. Note that in Figures 4(a) to (c), only a portion of the looper thread Y2 necessary for explaining the cutting is shown, not the entire thread.

[0018] In the sewing machine 1 of the present embodiment, three needles 2 are used. The three needles 2 are arranged in parallel in the horizontal direction and are provided such that their vertical positions are different. However, the number of needles 2 is not limited to three and can be arbitrarily set. The needle plate 3 is provided with a fabric feeding mechanism (not shown). By moving the fabric feeding mechanism in the fabric feeding direction from the front side to the rear side while protruding above the needle plate 3, the fabric is pushed from above by a fabric presser (not shown), and the fabric with its vertical position held is fed. The driving force for reciprocating the looper 4 is supplied from a rotating shaft for driving each part in the sewing machine 1 via a looper shaft 41 that extends horizontally and moves horizontally while rotating about its axis. Note that the source of the driving force is not particularly limited. Also, the reciprocating range of the looper 4 includes a horizontal range that extends left and right so as to include the positions directly below the needle drops 31 (three horizontally arranged positions in the present embodiment), and can be appropriately set according to the form of the seam (double loop stitch in the present embodiment) formed by the needle thread Y1 and the looper thread Y2. The above-mentioned "horizontal flow line" regarding the looper 4 is the main flow line, and the looper 4 reciprocates in a form that also includes secondary flow lines related to the swinging of the looper 4 in the fabric feeding direction (front-rear direction) for entangling the looper thread Y2 with the needle thread Y1. This reciprocating motion of the looper 4 occurs along with the motion of the looper shaft 41.

[0019] - Cutting mechanism - The sewing machine 1 of the present embodiment includes a cutting mechanism 5 for cutting the needle thread Y1 and the looper thread Y2 at a position below the needle plate 3. The cutting mechanism 5 is provided inside the sewing machine 1 covered by a cover. Specifically, as shown in FIGS. 1 to 3 with the cover removed, it is provided in a region to the right of the needle drop 31 inside the sewing machine 1. The cutting mechanism 5 of the present embodiment includes a base portion 51, a closing activation portion 52, a first transmission portion 53, a second transmission portion 54, a cutting portion 55 (fixed cutter 551, movable cutter 552), a movable cutter operation portion 56, and an opening adjustment portion 57.

[0020] The base portion 51 is flat and arranged such that its upper surface is horizontal. The base portion 51 is fixed to the horizontal upper surface of the main body side portion of the sewing machine 1 by screwing and is stationary in the sewing machine 1. The base portion 51 is a portion that supports each part that moves relative to the base portion 51.

[0021] The closing activation portion 52 is a protrusion that projects upward with reference to the base portion 51. This closing activation portion 52 is provided at the front end portion of a support plate 511 that is attached to the left end portion of the base portion 51 so as to partially overlap. The closing activation portion 52 is substantially cylindrical. However, it is not limited to this shape. As the closing activation portion 52 moves forward to the side (left side) closer to the needle drop 31 of the second transmission portion 54, it abuts against the movable female operation portion 56, thereby starting the closing operation of the female portion 55.

[0022] The first transmission portion 53 is arranged above the base portion 51 and is an elongated plate-like body that extends in a direction substantially along the front-rear direction. The proximal end (rear end) of the first transmission portion 53 is rotatably connected to a female actuator A that reciprocates in the lateral direction. The first transmission portion 53 is supported by the base portion 51 at a rotation fulcrum portion 531 and rotates such that the proximal end portion and the distal end portion (the front side end portion) move along an arc-shaped locus. The distal end portion of the first transmission portion 53 has a constricted shape such that the width dimension is once reduced, and further on the distal end side, it has a substantially circular shape in which the diameter dimension is larger than the constricted portion.

[0023] The second transmission unit 54, in combination with the first transmission unit 53, forms a link mechanism and converts the driving force of the female actuator A into the forward and backward movement of the female part 55 relative to the needle drop 31 and the looper 4. The second transmission unit 54 is an elongated plate-like body that is positioned on the upper surface of the base unit 51 so as to intersect its longitudinal direction with that of the first transmission unit 53 and extends laterally. The female part 55 is provided at the tip of the second transmission unit 54. The second transmission unit 54 is slidably mounted relative to the base unit 51. The second transmission unit 54 has a recess 541 that extends in the width direction formed on its rear side, and the substantially circular portion at the tip of the first transmission unit 53 fits into this recess 541. Preferably, the dimensional relationship between the inner periphery of the recess 541 and the substantially circular portion of the first transmission unit 53 is such that sliding is permitted without causing lateral play. The recess 541 allows for changes in the angle between the longitudinal direction of the first transmission section 53 and the longitudinal direction of the second transmission section 54, as the tip of the first transmission section 53 moves along an arc-shaped trajectory as described above. Therefore, the second transmission section 54 can be moved laterally as the first transmission section 53 rotates. A chamfer is formed at the open end of the recess 541 to prevent interference between the first transmission section 53 and the second transmission section 54, even when the first transmission section 53 is tilted relative to the second transmission section 54. The aforementioned constricted portion of the first transmission section 53 is also provided to prevent interference.

[0024] The second transmission section 54 has a base-side elongated hole 542, which is a through hole extending laterally, on the base end side (right side) farther from the needle drop 31, and a tip-side elongated hole 543, which is a through hole extending laterally, on the tip side (left side) closer to the needle drop 31. Each elongated hole is formed to be longer than the range of movement of the second transmission section 54. A pin fixed to the base section 51 and protruding upward passes through each elongated hole. The diameter of this pin is enlarged above the second transmission section 54 to prevent the second transmission section 54 from floating upward from the base section 51. The combination of each elongated hole and each pin determines the range of movement of the second transmission section 54 in the lateral direction. This range of movement corresponds to the range of movement between the standby position and the extended position of the female section 55, which will be described later. The base-side elongated hole 542 has a shape that extends in the linear direction. On the other hand, the tip-side elongated hole 543 is bent at an obtuse angle, forming a roughly V-shape, with the side closer to the needle drop 31 (left side) facing forward. This shape of the tip-side elongated hole 543 allows the second transmission section 54 to perform a "swinging" motion, where the tip faces backward, as it moves to the right, away from the needle drop 31 (corresponding to the movement of the female section 55 to the standby state, as described later).

[0025] The reason for the aforementioned "swinging" motion is that the pivot point of the female part 55 is a thick part through which the shaft passes, and therefore it is necessary to avoid interference with the base end (right end) of the looper 4. In addition, an elongated hole (not shown) is provided in the base part 51 below the pin. This elongated hole is formed to be longer in the direction along the dough feeding direction. Therefore, by adjusting the fixing position of the pin to the base part 51 in the direction along the dough feeding direction, the range of the aforementioned "swinging" motion can be adjusted. Accordingly, even if the movable female part 552 changes position so that it is not directly above the path of movement of the looper 4 when extended, due to the adjustment of the opening degree of the female part 55 by the opening degree adjustment part 57 described later, the aforementioned "swinging" adjustment can be used to adjust the movable female part 552 so that it is directly above the path of movement of the looper 4 when extended. In this adjustment, the positions of both the fixed female part 551 and the movable female part 552 (the position of the entire female part 55) are adjusted.

[0026] The female part 55 moves between the needle plate 3 and the looper 4 as it moves as a link mechanism relative to the base part 51 of the first transmission part 53 and the second transmission part 54, cutting the needle thread Y1 and looper thread Y2 that are connected to the fabric after sewing. The female part 55 comprises a fixed female part 551 that is immovable and a movable female part 552 that is rotatable around an axis in the vertical direction relative to the fixed female part 551 so as to perform a scissor-like operation in combination with the fixed female part 551. The fixed female part 551 and the movable female part 552 are separate components from the second transmission part 54 and are detachable from the tip of the second transmission part 54. In this embodiment, each female part 551, 552 has a pointed tip, but the shape of the tip is not particularly limited. However, with respect to the movable female part 552, as shown in Figure 4(a), it is advantageous for the tip to be pointed so that it can be inserted into the loop portion formed by the needle thread Y1.

[0027] The fixed blade 551 is a long, narrow plate in the horizontal direction and has a blade for cutting thread. The fixed blade 551 is fixed to the tip (left end) of the second transmission section 54. This fixing is done by screw. Therefore, if the blade is worn or damaged, the entire fixed blade 551 can be replaced by removing the screw. The fixed blade 551 moves relative to the needle plate 3 and looper 4 in accordance with the movement of the second transmission section 54. The edge of the blade of the fixed blade 551 is straight in plan view and, as shown in Figures 1 and 2, is inclined to be located towards the rear as it approaches the tip of the fixed blade 551.

[0028] The movable scalpel 552 is a long, narrow plate in the horizontal direction and has a blade for cutting thread. The fixed scalpel 551 and the movable scalpel 552 are stacked in the thickness direction. The movable scalpel 552 is rotatable around its vertical axis relative to the fixed scalpel 551. The blades of the fixed scalpel 551 and the blades of the movable scalpel 552 are positioned to face each other in a V-shape in a plan view (Figures 1 and 2), and can overlap as the movable scalpel 552 rotates (Figure 3). At the rotation center position, the movable scalpel 552 is stacked above the fixed scalpel 551. Therefore, the rotation trajectory of the movable scalpel 552 around its axis is located above the fixed scalpel 551. Consequently, as shown in Figure 3, when the two scalpels overlap, the movable scalpel 552 is located above the fixed scalpel 551. Similar to commonly used scissors, when the fixed blade 551 and the movable blade 552 are in a closed state with overlapping blades, the blades of both blades overlap, allowing the threads Y1 and Y2, which are sandwiched between the two overlapping blades and extending in the vertical direction, to be cut.

[0029] The movable scalpel operating section 56 functions to rotate the movable scalpel 552 relative to the fixed scalpel 551. The movable scalpel operating section 56 is connected to the base end (right side) of the movable scalpel 552. The movable scalpel operating section 56 has an elongated shape, with a portion bent and curved towards the rear as it extends to the right. The intermediate section 561 of the movable scalpel operating section 56 has a shape that extends diagonally. The closing start section 52 and the opening adjustment section 57 abut against the rear side edge of this intermediate section 561. The return spring 544 provided on the second transmission section 54 abuts against the front end edge of the intermediate section 561. In this embodiment, a torsion coil spring is used as the return spring 544, and the coil portion is pivotally supported in the second transmission section 54 in the lateral and front-rear directions. Furthermore, the tip of the rear arm of the return spring 544, which extends linearly, abuts against the front edge of the intermediate portion 561 of the movable scalpel operating section 56. The tip of the front arm is fixed to the second transmission section 54.

[0030] The movable scalpel 552 and the movable scalpel operating section 56 are integrally connected by a screw. The integrated movable scalpel 552 and movable scalpel operating section 56 rotate relative to the second transmission section 54 and the fixed scalpel 551. The movable scalpel operating section 56 is slidably mounted relative to the second transmission section 54. Of the rotations of the movable scalpel 552 and the movable scalpel operating section 56, the rotation in the direction of closing the scalpel section 55 occurs when the second transmission section 54 moves to the left toward the needle drop 31. As the movable scalpel operating section 56 moves along with the second transmission section 54, it comes into contact with the closing start section 52, which is fixed relative to the base section 51, and receives a pressing force toward the front from the closing start section 52. Due to this pressing force, the movable scalpel operating section 56 moves toward the front relative to the second transmission section 54, so the movable scalpel 552 on the opposite side of the scalpel rotation pivot point 58 moves toward the rear, opposite to the movable scalpel operating section 56. This closes the scalpel section 55. Furthermore, after each thread Y1 and Y2 is cut, when the second transmission unit 54 moves to the right so as to move away from the needle drop unit 31, the moving blade operating unit 56 moves away from the closing start unit 52. At this point, the spring force of the return spring 544 acts on the moving blade operating unit 56, returning it to a state where it is in contact with the opening adjustment unit 57.

[0031] In the sewing machine 1 of this embodiment, the relationship between the blade mechanism 5 and the main body of the sewing machine 1 (excluding the blade mechanism 5) is such that, as shown in Figure 2, a space S (see Figure 5) is secured between the needle plate 3 and the looper 4, allowing the blade part 55, which is in its pre-cutting position with its position changed relative to the cutting position. That is, in the sewing machine 1 of this embodiment, the blade mechanism 5 is positioned such that the blade part 55 (in this embodiment, the part of the movable blade 552 that is thicker than the blade pivot point 58, which has a screw and nut such as a bolt) is located between the needle plate 3 and the looper 4 in the vertical direction (see Figure 2). Here, since the looper thread Y2 held by the looper 4 is entangled with the needle thread Y1 held by the needle 2 to form a stitch, it is difficult to change the design to move the looper 4 far away from the needle plate 3. For this reason, the space S between the needle plate 3 and the looper 4 is not very large. In other words, the space S is narrow. Even in such a confined space S, the sewing machine 1 of this embodiment makes it possible to position the cutting blade 55 between the needle plate 3 and the looper 4, as described above, by devising the shape of the cutting blade 55 and the trajectory of its movement.

[0032] Furthermore, the second transmission unit 54, the fixed blade 551, the movable blade 552, and the movable blade operating unit 56 are each plate-shaped and are stacked and assembled in the thickness direction. The assembly is done by fastening with bolts or the like. Due to this configuration, the blade unit 55 can move in and out (advance and retreat) into the space secured between the needle plate 3 and the looper 4. Therefore, the complicated setting of the sewing machine 1 of this embodiment, in which only threads Y1 and Y2 are drawn out between the needle plate 3 and the looper 4 and thread cutting is performed at a position away from the needle drop 31, as in the conventional method due to physical interference, is unnecessary.

[0033] -Operation of the female mechanism- The blade mechanism 5 operates as follows: When sewing is performed with the needle 2 and looper 4 working together, the blade section 55 is in the standby state shown in Figure 1. In the standby state, the blade section 55 is located laterally (to the right) away from the needle drop 31 and is at the far right end of its range of movement. After sewing is completed, the operator of the sewing machine 1 operates a switch (not shown) provided on the sewing machine 1, and the blade actuator A is activated. As a result, the blade section 55 moves into an extended state, below the needle drop 31 (directly below the needle drop 31, but not limited to this) and above the looper 4. In the extended state, as shown in Figure 2, the movable blade 552 is located directly above the movement path of the looper 4, and the fixed blade 551 is located behind the movement path of the looper 4. As mentioned above, since the looper 4 swings in the front-to-back direction, the position of the looper 4 in the front-to-back direction at the end of sewing is not fixed but within a range of width. Therefore, assuming that the looper 4 is located in the middle of its oscillation range, the position "directly above the movement line of the looper 4" is defined. The position where the looper 4 is in the middle of its oscillation range corresponds to the position directly below the needle drop 31. In this embodiment, after sewing is completed, at the point when the moving knife 552 enters the loop portion formed by the needle thread Y1 (see Figure 4(a)), the looper 4 is located at the leftmost position in its reciprocating motion range and in the middle of its oscillation range.

[0034] Regarding the statement "positioned behind the movement path of the looper 4," more specifically, the plate-shaped portion of the movable blade 552 that is closer to the tip than the pivot point of the blade section 55 is positioned directly above the movement path of the looper 4. However, because this portion is plate-shaped and thin, it can be positioned without any problems. This allows for the closing operation of moving the movable blade 552 relative to the fixed blade 551 to be performed without any problems. On the other hand, as shown in Figure 5, the fixed blade 551 is positioned in the space S behind the looper 4 without overlapping it above the looper 4, and therefore does not interfere with the looper 4. Furthermore, even if the position in the front-to-back direction changes due to the oscillation of the looper 4, the fixed blade 551 in the extended state is positioned so as not to interfere. In the extended state, as shown in Figure 4(a), the movable blade 552 enters into the loop portion formed by the needle thread Y1. The fixed blade 551 is positioned behind the loop portion.

[0035] As the second transmission unit 54 moves further forward from the aforementioned state, a cutting operation is performed (the female part 55 closes) from the state shown in Figure 4(b) to the state shown in Figure 4(c), thereby cutting the needle thread (upper thread relative to the fabric) Y1 and the looper thread (lower thread relative to the fabric) Y2 below the fabric. From the advancement state to the cutting of the threads, the female part 55 closes while moving forward (Figures 2 and 3). As a result, the fixed female part 551 moves to the left, and the tip portion of the moving female part 552 moves diagonally to the left and backward. The loop-shaped needle thread Y1 is cut at the rear of the loop portion by the closing female part 55 (see Figures 4(b) and 4(c)). At this time, along with the needle thread Y1 (three threads, corresponding to the number of needles 2 in this embodiment), the looper thread Y2, which is entangled with the needle thread Y1 and located near the loop formed by the needle thread Y1, is also cut. At this time, in order for the two blades 551 and 552 to overlap, the movable blade 552 approaches the fixed blade 551, and as the movable blade 552 hooks each thread Y1 and Y2 and moves them backward while cutting them. More precisely, after the movable blade 552 hooks each thread Y1 and Y2 and moves them backward, the blade section 55 closes and cuts each thread Y1 and Y2. In particular with respect to the needle thread Y1, it is shown that the rear part of the loop bulges backward as the movable blade 552 moves between the state shown in Figure 4(a) and the state shown in Figure 4(b). After cutting each thread Y1 and Y2, the blade section 55 returns to the standby state. As it returns, the movable blade operating section 56 moves away from the closing start section 52. Because the spring force of the return spring 544 is applied to the movable blade operating section 56, the blade section 55 returns to the open state.

[0036] -Adjustment mechanism for the female mechanism- Next, the position adjustment of each part will be explained. The closing start unit 52 is adjustable in the front-to-back direction relative to the base unit 51. The support plate 511 on which the closing start unit 52 is provided has an elongated hole 512. This elongated hole 512 is longer in the direction along the dough feeding direction. The support plate 511 is screwed to the base unit 51. By adjusting the fixing position when screwing using the elongated hole 512, the contact position of the closing start unit 52 with respect to the movable knife operating unit 56, which moves together with the second transmission unit 54, can be adjusted in the front-to-back direction. This makes it possible to adjust the start timing of the closing operation of the movable knife 552 with respect to the fixed knife 551, and the position in the lateral and front-to-back directions at which the closing operation begins.

[0037] Here, if the opening degree of the female part 55 is the same when open, if the closing operation starts earlier, the insertion of the movable blade 552 into the loop portion formed by the needle thread Y1 will be shallower. In this case, as the movable blade 552 approaches the fixed blade 551, the distance over which the movable blade 552 hooks each thread Y1, Y2 and moves them backward increases (because the distance from the blade pivot point 58 to each thread Y1, Y2 is long), and the length of each thread Y1, Y2 remaining in the fabric after cutting increases by the amount they were moved backward. Conversely, if the closing operation starts later, the insertion of the movable blade 552 into the loop portion formed by the needle thread Y1 will be deeper. In this case, as the movable blade 552 approaches the fixed blade 551, the distance over which the movable blade 552 hooks each thread Y1 and Y2 and moves them backward becomes shorter (because the distance from the blade pivot point 58 to each thread Y1 and Y2 is shorter). As a result, the length of each thread Y1 and Y2 remaining in the fabric after cutting is shortened by the amount they were moved backward. In this way, the length of each thread Y1 and Y2 remaining in the fabric can be adjusted by adjusting the position of the closing start unit 52 relative to the base unit 51.

[0038] Furthermore, by adjusting the timing of the closing operation to be earlier, for example, the working time until the thread cutting is completed can be shortened. Therefore, by adjusting the position of the closing start unit 52 relative to the base unit 51, the operation of the scalpel mechanism 5 can be optimized to match the desired cutting method.

[0039] The opening degree adjustment unit 57 is attached to the second transmission unit 54 and the fixed female 551. The opening degree adjustment unit 57 is substantially disc-shaped, with an operating lever 571 protruding radially that can be grasped during operation. The opening degree adjustment unit 57 has a shape in which the diameter dimension changes in the circumferential direction, and the contact position with the movable female operating unit 56 can be adjusted by changing the circumferential position when it is fixed to the second transmission unit 54. When the opening degree adjustment unit 57 is fixed at a position with a large diameter dimension, the opening degree of the female part 55 when open (for example, in the standby state, the most open state defined by the return spring 544 and the opening degree adjustment unit 57) can be reduced, and when the opening degree adjustment unit 57 is fixed at a position with a small diameter dimension, the opening degree of the female part 55 when open can be increased. Therefore, the opening degree adjustment unit 57 makes it possible to adjust the opening degree of the fixed female 551 and the movable female 552 when open.

[0040] Here, assuming that the left-right positions of the female part 55 in the female mechanism 5 are the same, a smaller opening of the female part 55 when it is open allows the overlapping position of the blade of the fixed female 551 and the blade of the movable female 552 in the closing start state of the female part 55 to be positioned closer to the needle drop 31 in the front-to-back direction compared to when the opening of the female part 55 is larger. More specifically, assuming that the movable female 552 is positioned directly above the path of movement of the looper 4 when the female part 55 is extended, the position of the edge of the blade of the fixed female 551 (the part where each thread Y1, Y2 is cut by the fixed female 551) just before the closing operation starts can be positioned closer to the needle drop 31 (in the front-to-back direction). Cutting the threads closer to the needle drop 31 reduces the length of each thread Y1, Y2 remaining in the fabric. Therefore, by adjusting the opening of the female part 55, the cutting position of each thread Y1, Y2 can be adjusted.

[0041] Furthermore, a secondary fixing screw 59 for fixing the fixing female 551 to the second transmission unit 54 is provided adjacent to the side (specifically, the left side) of the opening degree adjustment unit 57. Both the opening degree adjustment unit 57 and the secondary fixing screw 59 adjacent to the opening degree adjustment unit 57 can have their fixing positions adjusted by large-diameter holes (not shown). This allows adjustment of the fixing position of the fixing female 551 relative to the second transmission unit 54. Note that this can also be done using elongated holes instead of large-diameter holes.

[0042] -summary- In the knife mechanism 5 of this embodiment, configured as described above, the cutting position of the knife section 55 for cutting the needle thread Y1 and looper thread Y2 can be changed relative to the needle plate 3. This position change is performed by adjusting the position of the fixed knife 551 in the fabric feeding direction (front-back direction) relative to the needle plate 3 at the time of cutting the needle thread Y1 and looper thread Y2. This position change can be performed by changing the opening of the knife section 55 using the opening adjustment section 57.

[0043] Thus, the cutting position of the blade section 55, which cuts the needle thread Y1 and looper thread Y2, can be changed relative to the needle plate 3. A space is secured between the needle plate 3 and the looper 4 in which the blade section 55 can be positioned in its pre-cutting position after being repositioned. Therefore, in the sewing machine 1 of this embodiment, it is not necessary to cut at a position far from the needle drop 31, as in conventional machines, and the cutting position can be changed to a desired position relative to the fabric after sewing to cut the needle thread Y1 and looper thread Y2. Accordingly, the cutting position of each thread Y1 and Y2 can be freely adjusted.

[0044] Since the cutting positions of each thread Y1 and Y2 can be freely adjusted, shortening the length of each thread Y1 and Y2 remaining in the fabric after cutting eliminates the need for manual trimming of remaining threads to improve the appearance, thus reducing the amount of work required. Incidentally, with the sewing machine 1 of this embodiment, it is possible to make the length of each thread Y1 and Y2 extending from the fabric as short as approximately 3 mm. Conversely, it is also easy to make the length of each thread Y1 and Y2 remaining in the fabric longer from the perspective of preventing fraying. Therefore, the sewing machine 1 equipped with the cutting mechanism 5 of this embodiment can meet a variety of user demands.

[0045] -Modified Embodiments- Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

[0046] For example, the looper 4 in the above embodiment was configured to reciprocate along a lateral path perpendicular to the dough feeding direction. However, it is not limited to this, and for example, it may be configured to reciprocate along a forward-backward (vertical) path along the dough feeding direction. It may also be configured to perform a motion that combines lateral and vertical reciprocation. Furthermore, the reciprocation is not limited to linear motion, but may also be arc-shaped motion.

[0047] Furthermore, in the above embodiment, the female part 55 was formed in a scissor shape by a fixed blade 551 and a movable blade 552 that constitute the female part 55 as a single unit. However, it is not limited to this, and the fixed blade 551 and the movable blade 552 may be separated, and the movable blade 552 may move relative to the fixed blade 551 to cut each thread Y1, Y2. In this case, the direction of movement of the movable blade 552 may be in the direction along the fabric feeding direction (front and back direction) or in the side direction (left and right direction). In this case, the length of each thread Y1, Y2 left in the fabric can be adjusted by the distance in a plan view between the blades of the fixed blade 551 and the blades of the movable blade 552 and the needle drop 31.

[0048] Furthermore, the configuration of the first transmission unit 53 and the second transmission unit 54 is not limited to a link mechanism as in the above embodiment, but can be changed in various ways. For example, the female part 55 may be configured to move forward and backward using gears or chains. Moreover, the female part 55 may be configured to move forward and backward not by a physical configuration, but by electrical control.

[0049] Furthermore, the fixed scalpel 551 in the above embodiment was configured to be fixed at a fixed position at the tip (left end) of the second transmission section 54. However, it is not limited to this, and the fixing position of the fixed scalpel 551 to the second transmission section 54 may be adjusted by means of an elongated hole or the like. With this configuration, the overlapping position of the blade of the fixed scalpel 551 and the blade of the moving scalpel 552 can also be adjusted on the side of the fixed scalpel 551. [Explanation of Symbols]

[0050] 1 Sewing machine 2 needles 3 Needle Plate 31. Needle drops 4 Looper 41 Looper axis 5. Female mechanism 51 Base section 511 Support plate 512 Long hole (support plate) 52 Closing Start Unit 53. First Communication Department 531 Pivot point 54 Second Transmission Department 541 recess 542 Base end elongated hole 543 Elongated hole at the tip 544 Return spring 55 Female part 551 Fixed scalpel 552 Moving female 56 Moving knife operation section 561 Middle section 57 Opening adjustment part 571 Operating lever 58 Female pivot point 59 Sub-fixing screws A female actuator Y1 Needle and thread Y2 Looper Yarn S space

Claims

1. A needle that moves up and down to penetrate the fabric being sewn, while holding the needle thread, A needle plate that supports the fabric from below and has a needle drop through which the vertically moving needle passes, Below the needle plate, a looper reciprocates while holding the looper thread and entangling the looper thread with the needle thread, It comprises a female part that moves between the needle plate and the looper and cuts the needle thread and the looper thread that are connected to the fabric after sewing, The female part is capable of changing the cutting position relative to the needle plate for cutting the needle thread and the looper thread. A sewing machine in which a space is secured between the needle plate and the looper, in which the cutting part, in the position before cutting is performed after being repositioned, can be placed.

2. The sewing machine according to claim 1, wherein the female part comprises a fixed female part which is immovable, and a movable female part which is rotatably provided relative to the fixed female part so as to perform a scissor-like operation in combination with the fixed female part.

3. The sewing machine according to claim 2, wherein the position change is made by adjusting the position of the fixed blade relative to the needle plate in the fabric feeding direction at the time of cutting the needle thread and the looper thread.

4. The aforementioned female part is in a standby state, away from the needle drop point, when sewing is performed. After sewing is complete, the needle enters an advanced position below the needle drop and above the looper, and from this position, a cutting operation is performed to cut the needle thread and the looper thread. The sewing machine according to claim 1 or 2, wherein it subsequently returns to the standby state.

5. The sewing machine according to claim 2 or 3, wherein the opening degree of the fixed blade and the movable blade when they are open can be adjusted.

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