JP4734874B2 - Sewing machine thread trimmer - Google Patents

Description

  In the present invention, even when a flocked pile member that prevents twisting of the upper thread is provided on the upper surface of the inner hook of the rotary hook, the upper and lower threads can be reliably caught by the thread catcher of the thread trimming device. About things.

  2. Description of the Related Art Conventionally, there has been provided a sewing machine including a thread trimming device for cutting an upper thread and a lower thread when sewing is interrupted or when sewing is completed. In this type of thread trimming device, the yarn catcher is provided so as to be able to reciprocate, the upper and lower yarns are caught by reciprocating the yarn catcher, and the captured upper and lower yarns are cut. It is.

  For example, the thread trimming device provided in the sewing machine of Patent Document 1 moves the thread catcher that can be reciprocated during thread cutting until the upper thread that has moved with the sword by the rotation of the outer hook is captured. During this period, the yarn catcher is temporarily stopped and waited. After that, the thread catcher is moved backward to catch the lower thread, and the upper thread and the lower thread captured by the thread catcher are cut at the same time in cooperation with a fixed cutting blade. is there.

By the way, in normal sewing, after the upper thread loop hooked by the sword of the rotary hook is pulled out from the inner hook, the upper thread loop is pulled up by a balance to form a seam. In some rare cases, the thread loop is loosened and twisted, and the upper thread loop is pulled up by the balance while the twisted state is formed to form a seam, resulting in a seam defect called a so-called towel seam ( For example, see Patent Document 2 (paragraph numbers [0006] and [0007]) .

Further, when the yarn catcher in the yarn trimming device catches the upper yarn, a catching error may occur due to the slack of the upper yarn loop. In order to prevent such poor sewing and catching error of the upper thread, a flocked pile member for lightly holding the upper thread loop from which the thread has been removed from the inner hook is attached to the upper surface of the inner hook, and the pile member There is a sewing machine in which measures are taken to prevent loosening of the upper thread loop and prevent twisting (see, for example, Patent Document 3 (paragraph numbers [0011] and [0020])) .

In addition, when embroidery sewing is performed without using the feed dog by the feed dog, the feed dog can be switched to a subsidence position that does not protrude from the upper surface of the needle plate in order to switch the cloth feed by the feed dog to an inactive state. Sewing machines provided with a feed dog subsidence mechanism are widely used (see, for example, Patent Document 4) .
JP 2003-284878 A (page 3, FIGS. 1 and 2) JP-A-11-342281 JP-A-7-5581 JP-A-4-371189

  In the thread trimming device provided in the sewing machine described in Patent Document 1 described above, a pile member is provided on the upper surface of the inner hook, a feed dog subsidence mechanism is provided, and the feed dog is sunk to the subsidence position by the feed dog subsidence mechanism. When sewing with the lower thread bobbin housed in the inner hook, the lower thread is always pressed against the pile member by the sinking feed dog, so the lower thread will sink into the pile member. Therefore, when the yarn catcher moves forward during yarn cutting, there is a problem that the lower yarn that has entered the inside of the pile member cannot be caught by the catching portion and the lower yarn cannot be cut.

  A thread trimming device for a sewing machine according to a first aspect is a thread trimming device disposed close to a rotary hook at a lower side of a needle plate of the sewing machine, and an upper thread and a lower thread extending from a cloth by reciprocating movement. In a thread trimmer having a thread catcher to be caught and a cutting blade for cutting an upper thread and a lower thread that have been caught by the thread catcher, the thread is pulled up by a balance of an upper thread loop removed from the inner hook of the rotary hook In this case, a flocked pile member for preventing twisting of the upper thread is provided on the upper surface of the inner hook, and a thread catching part for lifting the lower thread that has entered the pile member is provided on the thread catcher.

  When cutting the thread, even if the bobbin thread is embedded in the flocked pile member provided on the upper surface of the inner hook of the rotary hook, the thread hooking part provided on the thread catcher lifts the lower thread that has entered the pile member. Then, the floated lower thread is captured by the thread catcher, and the upper thread and the lower thread are cut in cooperation with the cutting blade.

  A thread trimming device for a sewing machine according to a second aspect of the present invention is the sewing machine according to the first aspect, wherein the thread catcher includes a first thread catcher that catches the upper thread and the lower thread on the fabric side, the upper thread and the bobbin side on the needle side. A second yarn catching portion that catches the lower yarn, and the lower end of the yarn hooking portion is formed lower than the lower end of the second yarn catching portion.

  A thread trimming device for a sewing machine according to a third aspect of the present invention is the sewing machine according to the second aspect, wherein the yarn hooking portion is separated from the second yarn catching portion by a predetermined distance downstream in the forward movement direction of the yarn catching body. The lower end portion of the yarn hooking portion is formed in an acute angle shape, and the tip portion formed in the acute angle shape is provided in a direction toward the second yarn catching portion side.

  A thread trimming device for a sewing machine according to a fourth aspect of the present invention is the sewing machine according to any one of the first to third aspects, wherein the yarn hooking section hooks the lower thread that has entered the pile member until the yarn catcher completes the forward movement. It is provided at a position to lift up.

  A thread trimming device for a sewing machine according to a fifth aspect of the present invention is the sewing machine according to any one of the first to fourth aspects, wherein the thread sliding contact portion from the yarn hooking portion to the base end portion of the yarn catching body is in sliding contact with the upper thread. It is a shape that is continuously connected by a movable straight line or curve.

  According to the first aspect of the present invention, a flocked pile member is provided on the upper surface of the inner hook so as to prevent twisting of the upper thread when the upper thread loop removed from the inner hook of the rotary hook is pulled up by the balance. Since the thread catcher has been provided in the thread catcher to lift the submerged lower thread, the lower thread is embedded in the flocked pile member provided on the upper surface of the rotary hook when cutting the thread. Even in this case, the thread hook provided on the thread catcher can lift the lower thread that has entered the pile member, and the raised lower thread can be captured by the thread catcher. The thread and the lower thread can be cut reliably.

  According to a second aspect of the present invention, the yarn catcher includes a first yarn catcher that catches the upper thread and lower thread on the fabric side, and a second thread catcher that catches the upper thread on the needle side and the lower thread on the bobbin side. Since the lower end of the yarn hooking portion is formed lower than the lower end of the second yarn catching portion, the effect of raising the lower yarn by the yarn hooking portion can be enhanced. First, the second yarn catching portion closer to the bobbin outlet side of the lower yarn than the first yarn catching portion can be caught, and subsequently, the lower yarn can also be caught by the first yarn catching portion. Other effects similar to those of the first aspect are obtained.

  According to the invention of claim 3, the yarn hooking portion is integrally formed with the yarn catching body at a predetermined distance downstream from the second yarn catching portion in the forward movement direction of the yarn catching body, and the lower end portion of the yarn hooking portion. Is formed in an acute angle shape, and the tip portion formed in the acute angle shape is provided in a direction toward the second yarn catching portion side, so that the yarn catching body sinks into the pile member when moving in the forward movement direction. The lower thread can be securely hooked and raised at the sharp tip of the thread hook, and when the thread catcher moves in the backward movement direction, the lower thread hooked by the thread hook is transferred to the second thread catcher. Can be captured. Other effects similar to those of the second aspect are achieved.

  According to the invention of claim 4, since the yarn hooking portion is provided at a position for hooking and lifting the lower thread that has entered the pile member by the time the forward movement of the yarn catcher is completed, the yarn catcher is moved forward. In the middle of movement, the lower thread that has entered the pile member is hooked and lifted by the thread hook, and can be held in the trapped state. The yarn can be transferred to and captured by the second yarn capturing section. Other effects similar to those of any one of claims 1 to 3 are provided.

  According to the invention of claim 5, the yarn sliding contact portion from the yarn hooking portion to the base end portion of the yarn catching body has a shape that is continuously connected by a straight line or a curve in which the upper yarn can slide and move. When the upper thread moves to the thread catcher along the thread catcher by the rotation of the rotary hook after the thread catcher has finished moving in the forward movement direction, the thread catcher is continuously formed. The thread catching portion can be held in a trapped state via a straight or curved thread sliding contact portion, and when the yarn catcher returns, the second thread catching portion catches the upper thread and the lower thread without any trouble. be able to. Other effects similar to those of any one of claims 1 to 4 can be achieved.

  The thread cutting device of the sewing machine according to the present embodiment hooks the lower thread with the thread hooking portion provided in the thread catcher even when the lower thread enters the flocked pile member provided on the upper surface of the inner hook of the rotary hook. After being lifted up, it can be caught by the yarn catcher.

  As shown in FIG. 1, the sewing machine 1 has a bed portion 2 having a horizontal plane, a pedestal column portion 3 erected upward from the right portion of the bed portion 2, and the pedestal column portion 3 so as to face the bed portion 2. The arm portion 4 extends horizontally.

  The arm portion 4 is provided with a liquid crystal display 5 with a touch panel, and a pattern to be sewn can be selected by display. A needle bar drive mechanism, a presser foot drive mechanism, a balance drive mechanism, a threading mechanism and the like (not shown) are provided at the left end portion in the arm portion 4.

  A lower shaft 6 facing in the left-right direction is disposed inside the bed portion 2, and is pivotally supported by a sewing machine frame (not shown). A feed dog drive mechanism (not shown) for driving the feed dog 7 in the front-rear direction and the up-down direction, a horizontal rotary hook 8, an upper thread 31, and a lower thread 30 are cut at the left end portion of the lower shaft 6. A feed dog subsidence mechanism (not shown) for switching the feed dog 7 so as to be held at the subsidence position is provided.

  A needle plate 9 is disposed on the bed portion 2 corresponding to the upper side of the horizontal rotary hook 8, and the needle plate 9 has a needle hole 9a (see FIG. 2) that allows a sewing needle (not shown) to move up and down. Is formed. The feed dog 7 is formed with an opening 7a for allowing the sewing needle to move up and down.

  Next, the thread trimming device 10 provided at the left end of the bed 2 will be described. The thread trimming device 10 is unitized by a base upper plate 11 and a base lower plate 12, and is disposed immediately to the left of the horizontal rotary hook 8.

  As shown in FIG. 2, the base upper plate 11 has through-holes 11 a extending in the left-right direction. A thin plate-shaped resin guide member 13 is formed around the through-holes 11 a on the upper surface of the base upper plate 11. Are fixed at multiple locations. Further, the lower end portion of the cutting blade 14 disposed in the left-right direction for cutting the upper yarn 31 and the lower yarn 30 in cooperation with the yarn catcher 15 described later is fixed to the right end portion on the front side of the guide member 13. ing. The blade portion of the cutting blade 14 is the right end portion.

  On the upper surface side of the guide member 13, a thread catcher 15 (see FIG. 8A) is disposed in the left-right direction, and is provided in a horizontal drive unit 15 a formed at the base end of the thread catcher 15. Further, two downwardly directed guide pins 16 and 17 are fitted in the through-hole 11a so as to be movable.

  As shown in FIG. 8-2, the first yarn catching portion that catches the upper thread 31 and the lower yarn 30 on the cloth side at the front end portion of the catching body portion 15 b that is linear and has a cross-sectional gate shape of the yarn catching body 15. 15e and a second thread catching portion 15f for catching the needle-side upper thread 31 and the lower thread bobbin 26-side lower thread 30 are formed. That is, the first yarn catching portion 15e is formed at the front end portion of the rear vertical wall 15c of the catching main body portion 15b, and the second yarn catching portion 15f is placed at the front end portion of the front vertical wall 15d of the catching main body portion 15b. A predetermined dimension is formed on the downstream side in the forward movement direction FD of the yarn catcher 15 with respect to the catcher 15e.

  As shown in FIGS. 5 and 6, the capturing main body portion 15 b having the above-described cross-sectional gate shape is disposed at a position so as to cover the cutting blade 14 fixed to the guide member 13 from above. When the yarn catcher 15 reciprocates in the left-right direction along the through long hole 11 a of the base upper plate 11, the catch body 15 b inner side reciprocates without contacting the cutting blade 14.

  In this way, the yarn catching body 15 reciprocates, whereby the lower yarn 30 and the upper yarn 31 are caught and then cut by the cutting blade 14. An inclined end portion is formed in a protruding shape at the front end portion of the first yarn catching portion 15e in the forward movement direction FD, so that the yarn catcher 15 can easily get over the lower yarn 30 when moving in the forward movement direction.

  By the way, as shown in FIG. 8B, the yarn catching portion 15g is separated from the second yarn catching portion 15f of the front vertical wall 15d by a predetermined distance downstream in the forward movement direction FD of the yarn catching body 15. 15 is integrally formed. Further, the yarn sliding contact portion 15h extending from the yarn hooking portion 15g to the base end portion of the catching main body portion 15b is formed in a continuous shape, and the lower end of the yarn hooking portion 15g is lower than the lower end of the second yarn catching portion 15f. Is also formed lower by a predetermined dimension t, and the lower end portion of the yarn hooking portion 15g toward the second yarn catching portion 15f is formed in an acute angle shape.

  As shown in FIGS. 5 and 6, the thread cutting motor 18 is fixed to the lower surface of the base lower plate 12 with screws, and the drive gear 20 fixed to the motor shaft is located above the base lower plate 12. . The drive gear 20 is meshed with a large-diameter gear 21 a of a resin transmission gear 21.

  On the other hand, as shown in FIGS. 2 and 3, the fan-shaped gear 23 disposed on the lower side of the base upper plate 11 is rotated at the base end portion thereof by the vertical support pins 24 fixed to the base upper plate 11. The fan-shaped gear 23 that is pivotally supported is meshed with the small-diameter gear 21b that is integrally formed with the large-diameter gear 21a.

  A base end portion of the swing lever 25 is pivotally supported on the support pin 24, and the sector gear 23 and the swing lever 25 are integrally fixed by a connecting pin 25a. Therefore, the sector gear 23 and the swing lever 25 swing together as the transmission gear 21 rotates. A long hole 25b is formed in the front end side portion (rear end side portion) of the swing lever 25, and the guide pin 16 on the left side of the yarn catcher 15 is fitted in the long hole 25b.

  When the thread cutting motor 18 rotates clockwise in a plan view, the thread catching body 15 is guided by the elongated hole 25b through the drive gear 20, the fan-shaped gear 23, and the swing lever 25, as shown in FIG. It moves in the forward movement direction FD to the maximum forward movement position shown. On the other hand, when the yarn cutting motor 18 rotates counterclockwise, the backward direction RD (the direction opposite to the forward direction FD) is reached to the standby position shown in FIG. Move to.

  By the way, the lower thread bobbin accommodated in the upper surface of the inner hook 8a of the horizontal rotary hook 8 described above and corresponding to the thread path of the lower thread 30 adjacent to the foremost end of the feed dog 7, that is, the inner hook 8a. As shown in FIGS. 2 and 9, a large number of bristles of a predetermined length are densely packed in the thread path of the lower thread 30 fed from 26 through the feed dog 7 to the needle hole 9 a of the needle plate 9. A rectangular pile member 28 is bonded and fixed in a plan view after planting. The pile member 28 is for preventing the upper thread 31 from being twisted when the upper thread 31 loop removed from the inner hook 8a is pulled up by a balance.

  Therefore, during normal sewing in which the feed dog 7 moves up and down, the lower thread 30 does not sink into the pile member 28 but moves near the surface of the pile member 28. However, at the time of sewing in which the feed dog 7 is held in its lowered position by the feed dog lowering mechanism, the lower thread 30 fed from the lower thread bobbin 26 is always pressed against the pile member 28 by the lower side of the feed dog 7. Therefore, the lower thread 30 from the lower thread bobbin 26 is fed out in a state where it has entered the inside of the pile member 28.

  Next, the operation and effect of the yarn catcher 15 at the time of yarn cutting will be described. In this case, however, it is assumed that the feed dog 7 is held at the sink position by the feed dog sinking mechanism. Therefore, as shown in FIGS. 10 and 11-2, the lower thread 30 from the lower thread bobbin 26 is fed out through a state where the lower thread 30 sinks into the pile member 28 due to the subsidence state of the feed dog 7.

  Thus, during the sewing operation in which the cloth feed by the feed dog 7 is not executed, the thread catcher 15 is waiting at the standby position shown in FIG. At the time of thread cutting at the end of sewing, as described above, the thread catching body 15 moves in the forward movement direction FD by the clockwise rotation of the thread cutting motor 18 (see FIGS. 11-1 and 11-2).

  As shown in FIGS. 12A and 12B, the first yarn catching portion 15e and the second yarn catching portion 15f are pile members in the middle of the yarn catching body 15 until the forward movement in the forward movement direction FD is completed. 28, the lower end of the yarn hooking portion 15g is formed lower than the lower end of the second yarn catching portion 15f, and the lower end portion of the yarn hooking portion 15g on the second yarn catching portion 15f side is an acute angle. Therefore, even if the lower thread 30 is submerged in the pile member 28, the thread hooking portion 15g extends below the submerged lower thread 30. Therefore, the acute angle of the thread hooking portion 15g is increased. The lower thread 30 that has entered the tip of the thread is securely hooked and lifted.

  At this time, the upper thread 31 is not captured by the sword (not shown) provided in the outer hook 8 b of the horizontal rotary hook 8. Therefore, the yarn catching body 15 moves backward by a predetermined distance in the backward movement direction RD, and the lower yarn 30 held in the catching state by the yarn hooking portion 15g is taken over by the second yarn catching portion 15f and then caught. The capturing body 15 temporarily stops near the center of the horizontal rotary hook 8.

  Thus, while the yarn catcher 15 is stopped, the upper thread 31 hooked on the tip of the sword moves to the tip end while sliding on the yarn slide contact portion 15h of the yarn catcher 15 due to the counterclockwise rotation of the sword tip. (See FIG. 12-2), and is held in the trapped state by the yarn hooking portion 15g.

  At this time, when the yarn catching body 15 starts to return again in the backward movement direction RD by driving the yarn cutting motor 18, as shown in FIGS. 13-1 and 13-2, the lower yarn 30 and the upper yarn 31 Both of which are caught by the second yarn catching portion 15f and the first yarn catching portion 15e and returning to the standby position, the lower yarn 30 between the first yarn catching portion 15e and the second yarn catching portion 15f. And the upper thread 31 come into contact with the cutting blade 14, and then the lower thread 30 and the upper thread 31 are simultaneously cut by the cutting blade 14.

  Thus, a flocked pile member 28 is provided on the upper surface of the inner hook 8a to prevent the upper thread 31 from being twisted when the upper thread loop is lifted by the balance of the upper thread loop removed from the inner hook 8a of the horizontal rotary hook 8. Since the thread catching portion 15g for lifting the lower thread 30 that has entered the member 28 is provided in the thread catcher 15, the pile member 28 provided on the upper surface of the inner hook 8a of the horizontal rotary hook 8 when the thread is cut. Even when the yarn catches in the pile member 28, the yarn catching portion 15 g provided in the yarn catcher 15 can lift the lower thread 30 that has entered the pile member 28, and the lower catcher 30 lifted up by the yarn catcher 15. Since it can be captured, the lower thread 30 and the upper thread 31 can be reliably cut in cooperation with the cutting blade 14.

  The yarn catcher 15 includes a first yarn catcher 15e that catches the upper thread 31 and the lower thread 30 on the cloth side, and a second yarn catcher 15f that catches the upper thread 31 on the needle side and the lower thread 30 on the bobbin side. Since the lower end of the yarn hooking portion 15g is formed lower than the lower end of the second yarn catching portion 15f, the lowering effect of the lower yarn 30 by the yarn hooking portion 15g can be enhanced, and the lower First, the thread 30 can be captured by the second thread capturing section 15f closer to the lower thread bobbin 26 outlet side of the lower thread 30 than the first thread capturing section 15e, and then also to the first thread capturing section 15e. The lower thread 30 can be captured.

  Further, the yarn hooking portion 15g is integrally formed with the yarn catching body 15 at a predetermined distance from the second yarn catching portion 15f on the downstream side in the forward movement direction FD of the yarn catching body 15, and the lower end portion of the yarn hooking portion 15g has an acute angle. Since the tip portion formed in the shape of an acute angle is provided in the direction toward the second yarn catching portion 15f side, the yarn catching body 15 sinks into the pile member 28 when moving in the forward movement direction. The lower thread 30 can be reliably hooked and lifted by the sharp-angled tip of the thread hooking portion 15g, and the lower thread 30 hooked by the thread hooking portion 15g is moved to the first position when the thread catcher 15 moves in the backward movement direction. The two yarn catcher 15f can take over and take over.

  Further, since the yarn hooking portion 15g is provided at a position where the lower yarn 30 that has entered the pile member 28 is hooked and lifted up until the forward movement of the yarn catcher 15 is completed, the yarn catcher 15 is moved in the forward movement direction. During the movement, the lower thread 30 that has entered the pile member 28 is hooked and lifted by the thread hooking portion 15g and can be held in the trapped state, and is held in the trapped state by the thread hooking portion 15g when the yarn trapping body 15 is moved back. The lower thread 30 can be transferred to and captured by the second thread capturing portion 15f.

  Further, the yarn sliding contact portion 15h from the yarn hooking portion 15g to the base end portion of the yarn catching body 15 has a shape that is continuously connected by a straight line in which the upper thread 31 can slide and move. After the movement in the forward movement direction is completed, when the upper thread 31 moves to the thread catching portion 15g along the thread catching body 15 by the rotation of the horizontal rotary hook 8, it is continuously formed on the thread catching body 15. The thread catching portion 15g can be held in the trapped state via the straight thread sliding contact portion 15h, and when the yarn trapping body 15 moves backward, the lower thread 30 and the upper thread 31 are trapped by the second thread catching portion 15f. Can be performed without any problems.

  Next, a modified form of the embodiment will be described.

  1] The yarn sliding contact portion 15h from the yarn hooking portion 15g of the yarn catching body 15 to the base end portion may have a shape that is continuously connected by a curved curve in which the upper yarn 31 is slidable and movable.

  2] The depth at which the lower thread 30 sinks into the pile member 28 varies depending on the thickness and length of the hair to be implanted in the pile member 28, the degree of density, the size of the pile member 28, and the like. It is desirable to appropriately set the dimension t for lowering the lower than the lower end of the second yarn catching portion 15f to a dimension larger than the depth of penetration.

  3) The present invention is not limited to the above-described embodiments and modifications thereof, and those skilled in the art can implement various modifications to the above embodiments without departing from the spirit of the present invention. The present invention includes such modifications.

It is a front view of the sewing machine concerning the example of the present invention. It is a top view of the thread trimmer provided in the sewing machine which concerns on the Example of this invention, and a horizontal rotary hook. It is a bottom view of a thread trimming device. It is a front view of a thread trimming device. It is a right view of a thread trimming device. It is a left view of a thread trimming device. It is a rear view of a thread trimming device. It is a top view of a thread catcher. It is a front view of a yarn catcher. FIG. 3 is a vertical side view taken along line II of FIG. 2 when the lower thread is on the upper side of a pile member. FIG. 10 is a view corresponding to FIG. 9 when the lower thread has entered the pile member. It is a top view of the thread | yarn catcher which moves to a horizontal rotary hook and a forward movement direction. It is a KK line longitudinal front view of Drawing 11-1. It is a top view of the thread | yarn catcher which completed the horizontal rotary hook and the moving direction. It is the LL line vertical front view of FIG. It is a top view of the thread catcher which completes a horizontal rotary hook and a backward movement. It is the MM line vertical front view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sewing machine 8 Horizontal rotary hook 8a Inner hook 9 Needle plate 10 Thread trimming device 14 Cutting blade 15 Thread catcher 15e First thread catcher 15f Second thread catcher 15g Thread hook 15h Thread sliding contact 28 Pile member 30 Lower thread 31 Upper thread 26 Lower thread bobbin

Claims (5)

A thread trimming device disposed near a rotary hook at a lower side of a needle plate of a sewing machine, and a thread catcher that catches an upper thread and a lower thread extending from a cloth by reciprocation, and a thread catcher In a thread trimmer having a cutting blade for cutting the captured upper thread and lower thread,
A flocked pile member is provided on the upper surface of the inner hook to prevent twisting of the upper thread when the thread is pulled by the balance of the upper thread loop removed from the inner hook of the rotary hook.
A yarn hooking portion for lifting the lower thread that has entered the pile member is provided on the yarn catcher.
A thread trimming device for a sewing machine.   The yarn catcher has a first yarn catcher for catching the upper thread and lower thread on the fabric side, and a second thread catcher for catching the upper thread on the needle side and the lower thread on the bobbin side. The sewing machine thread trimming apparatus according to claim 1, wherein a lower end of the sewing machine is formed lower than a lower end of the second thread catching portion.   The yarn hooking portion is integrally formed with the yarn catching body at a predetermined distance from the second yarn catching portion downstream in the forward movement direction of the yarn catching body, and the lower end portion of the yarn hooking portion is formed in an acute angle shape, The thread trimming device for a sewing machine according to claim 2, wherein a tip portion formed in an acute angle is provided in a direction toward the second yarn catching portion.   The said thread hook part is provided in the position which hooks and raises the bobbin thread which sunk in the said pile member by the time of the completion of the forward movement of a thread | yarn catcher, The Claim 1 characterized by the above-mentioned. Sewing machine for thread trimming. The yarn sliding contact portion from the yarn hooking portion to the base end portion of the yarn catching body has a shape that is continuously connected by a straight line or a curve in which the upper thread is slidable and movable. A thread trimming device for a sewing machine according to any one of the above.