JP2005278931A - Needle thread clamping mechanism of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a construction of a needle thread clamping mechanism so that a sewing machine becomes small, light and cheap and the needle thread clamped by the above mechanism is prevented to be sewn into a seam of a thread end section. <P>SOLUTION: The needle thread clamping mechanism of the sewing machine includes a first thread clamping plate 21 which is attached on a lower surface of a throat plate 12, a second thread clamping plate 22 which has a thread hole 22b to allow a sewing needle which penetrates a needle hole of the throat plate 12 to pass through and clamps the thread end section cooperating with the first throat plate 21, and a turning driving mechanism 35 which drives and turns the second thread clamping plate 22 covering a starting position where its thread hole 22b overlaps the needle hole of the throat plate 12, a clamping position where it clamps the thread end section cooperating with the first thread clamping plate 21, and a releasing position where the clamp of the thread end section is released, wherein the turning driving mechanism 35 has a thread clamping motor 36 which can perform the turning driving from the starting position to the clamping position and a thread releasing solenoid 49 which is used for the rotation driving from the clamping position to the releasing position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an upper thread clamping mechanism of a sewing machine, and in particular, when forming stitches for several stitches at the start of sewing, the thread end of the upper thread is clamped below the needle plate, and the stitch skipping at the start of sewing is performed. It relates to the thing which prevented it.

  Conventionally, in various types of sewing machines such as a bar-tacking machine that forms a bar-tacking seam, at the start of sewing, depending on the type of work cloth and upper thread, the upper thread may come off from the eye of the sewing needle due to the lifting of the balance, Seams may not be formed. Therefore, at the start of sewing, when the sewing needle descends from the uppermost position and passes through the needle hole of the needle plate and then moves to the upper side of the needle plate during the next upward movement, Various types of upper thread holding devices for sewing machines have been proposed in which the thread ends of the thread are held until several stitches are formed to prevent stitch skipping at the start of sewing.

  For example, an upper thread clamp device of a sewing machine described in Japanese Patent No. 2671478 is provided with a support block, a guide bar, an air cylinder, etc. on the lower side of a needle plate, and the thread clamp is aligned with the needle hole at the start of sewing. When the sewing machine moves to the first movement position and the sewing needle of the first stitch moves to the upper side of the needle plate, the thread clamp moves from the first movement position to the second movement position, and the thread end cooperates with the lower surface under the needle. When a predetermined number of stitches (for example, 2 stitches) are sewn, the thread clamp rotates and the thread retainer moves downward to release the upper end. (For example, refer to Patent Document 1).

Japanese Patent No. 2671478 (pages 2 and 3, FIG. 1)

  In the upper thread clamp device of the sewing machine described in the above-mentioned Japanese Patent No. 2671478, a plurality of air cylinders, support blocks, guide bars, etc. Since the upper thread gripping device is configured by providing a plurality of members, the upper thread gripping device is complicated and enlarged, the bed portion is enlarged, the manufacturing cost is increased, and the weight cannot be reduced. There are problems such as.

  An upper thread clamping mechanism of a sewing machine according to claim 1 is a needle thread clamping mechanism for a sewing machine that releasably clamps the thread end portion of the upper thread extending from the stitch hole of the sewing needle below the needle plate of the bed portion. And a second thread that has a thread hole that allows a sewing needle to pass through the needle hole of the needle plate and cooperates with the first thread clamping member to clamp the thread end. Driving means for moving the clamping member and the second thread clamping member over a start position for starting the clamping of the thread end, a clamping position for clamping the thread end, and a release position for releasing the clamping of the thread end. The drive means includes a stepping motor capable of executing movement from the start position to the clamping position and at least a solenoid actuator used for movement from the clamping position to the release position.

  When the second thread clamping member is at the start position, the thread hole of the second thread clamping member and the needle hole of the needle plate match, so that the sewing needle can pass and sewing is started. When the first sewing needle after the start moves to the upper side of the needle plate, the second thread clamping member is moved to the clamping position by the stepping motor of the driving means, so that the yarn end portion cooperates with the first thread clamping member. Is pinched. When the sewing for several stitches is executed, the second thread clamping member is moved to the release position by the solenoid actuator of the driving means, so that the thread end portion is released. Therefore, there is no skipping at the start of sewing.

  The upper thread clamping mechanism of the sewing machine according to a second aspect is the invention according to the first aspect, wherein the driving means drives the second thread clamping member to rotate between a start position, a clamping position, and a release position. In this case, the second thread clamping member is sequentially rotated over the start position, the clamping position, and the release position by the rotation of the driving unit.

  The upper thread clamping mechanism of the sewing machine according to claim 3 is the invention according to claim 2, wherein the first thread clamping member is pivotally attached to the needle plate by a vertical pin member, It is configured to be able to rotate between a clamping position for clamping the yarn end portion in cooperation and a release position for releasing the clamping of the yarn end portion. In this case, since the first thread clamping member is pivotally attached to the needle plate by the vertical pin member, the first thread clamping member cooperates with the first thread clamping member when rotating the second thread clamping member to the clamping position. Then, the yarn end is clamped, and when the second yarn clamping member is rotated to the release position, the first yarn clamping member is also rotated to the release position, and the clamping of the yarn end is released.

  The upper thread clamping mechanism of the sewing machine according to claim 4 is characterized in that, in the invention of claim 2, the clamping position is at a position where the second thread clamping member is rotated by a first angle with respect to the start position, and is relative to the clamping position. The release position is the position where the second thread clamping member is rotated by the second angle in the same direction as the first angle. In this case, the second thread clamping member rotates from the starting position to the clamping position by the rotation of the first angle, and further rotates from the clamping position to the release position by the rotation of the second angle in the same direction. Since the thread end portions at the clamping position and the release position are located to the side of the position of the sewing needle, the thread end portions are not sewn during sewing when the thread end portion is clamped.

  The upper thread clamping mechanism of the sewing machine according to claim 5 is the sewing machine according to claim 4, wherein the elastic member that biases the first thread clamping member toward the clamping position and the biasing force of the elastic member to the first thread clamping member. And a locking member that locks to the clamping position, and the second thread clamping member rotates from the clamping position to the release position by engagement when the second thread clamping member rotates from the clamping position to the release position. The engaging member to be operated is provided on the second thread clamping member.

  In this case, since the rotation of the first thread clamping member to a position other than the clamping position is suppressed by the urging force of the elastic member, the second thread clamping member rotated to the clamping position and the first position held at the clamping position are held. A yarn end is clamped with one yarn clamping member. When rotating the second thread clamping member from the clamping position to the release position, the first thread clamping member is engaged with the engaging member provided on the second thread clamping member, and released against the urging force of the elastic member. Although a large torque is required to rotate to the position, it is rotated at once to the release position by the large driving force of the solenoid actuator.

  The upper thread clamping mechanism of the sewing machine according to claim 6 is the invention according to any one of claims 3 to 5, wherein the rotation fulcrum of the first thread clamping member is provided on the root side in the length direction of the bed rather than the needle hole. In addition, the rotation fulcrum of the second thread clamping member is provided further on the root side than the rotation fulcrum of the first thread clamping member. In this case, when the second thread clamping member is rotated to the clamping position, the clamping part of the second thread clamping member and the clamping part of the first thread clamping member located at the clamping position overlap with each other. The part is pinched. However, when the second yarn clamping member is rotated to the clamping position, the two nip portions are displaced due to the difference of the rotation fulcrum, and the yarn hole of the second yarn clamping member is opened. The clamping of the part is released.

  The upper thread clamping mechanism of the sewing machine according to claim 7 is expanded to the moving side to the first thread clamping member at the tip end portion having the thread hole of the second thread clamping member according to any one of claims 1 to 6. And a part of the enlarged portion is superposed on the first yarn clamping member at least at the start position of the second yarn clamping member. In this case, since the enlarged portion formed on the moving side of the tip portion having the thread hole of the second yarn clamping member to the first yarn clamping member is superposed on the first yarn clamping member at least at the start position, When the second thread clamping member rotates to the clamping position, the second thread clamping member can smoothly move while maintaining a predetermined moving speed without colliding with the first thread clamping member through overlapping with the first thread clamping member of the enlarged portion. Move to the clamping position.

  The upper thread clamping mechanism of the sewing machine according to claim 8 is the invention according to any one of claims 1 to 7, wherein the origin position of the second thread clamping member associated with the initial setting of the stepping motor is set to a start position. Is. In this case, when the initial setting of the stepping motor is executed, the second thread clamping member rotates to the start position which is the origin position. Therefore, even if the sewing starts immediately at the start position, There is no interference with the thread clamping member.

  According to a ninth aspect of the present invention, the upper thread clamping mechanism of the sewing machine according to any one of the first to eighth aspects is provided with a first detection sensor for detecting that the second thread clamping member is at a start position. . In this case, the first detection sensor detects that the second thread clamping member has rotated to the start position.

  According to the first aspect of the present invention, the first thread clamping member, the second thread clamping member, and the driving means are provided, and the driving means is a stepping motor capable of executing movement from the starting position to the clamping position, and at least And a solenoid actuator used for movement from the clamping position to the release position, so that sewing is started when the second thread clamping member is moved to the start position by the stepping motor of the driving means, and the first sewing needle after the start is When the second thread clamping member is moved to the upper side of the needle plate, the second thread clamping member is moved to the clamping position, so that the thread end can be reliably clamped by the cooperation of the second thread clamping member and the first thread clamping member. it can.

  On the other hand, when the stitches for several stitches are executed, the second thread clamping member is moved to the release position by the solenoid actuator and the thread end is released, so that skipping at the start of sewing is reliably prevented. be able to.

  According to the second aspect of the present invention, the driving means rotationally drives the second thread clamping member over the start position, the clamping position, and the release position, so that the upper thread clamping is compared with a moving mechanism that moves linearly. The drive system of the mechanism can be simplified, the sewing machine can be reduced in size and weight, and further the cost can be reduced. Other effects similar to those of the first aspect can be obtained.

  According to the invention of claim 3, the first thread clamping member is pivotally attached to the needle plate by a vertical pin member so as to clamp the thread end portion in cooperation with the second thread clamping member. Since it is configured to be rotatable over the position and the release position for releasing the clamping of the yarn end portion, the yarn end portion cooperates with the first yarn clamping member when rotating the second yarn clamping member to the clamping position. Further, when the second thread clamping member is rotated to the release position, the first thread clamping member is also rotated to the release position, whereby the thread end portion can be released. In addition, the same effect as in claim 2 can be obtained.

  According to the invention of claim 4, the clamping position is at a position where the second thread clamping member is rotated by a first angle with respect to the start position, and the release position is at the first thread clamping member with respect to the clamping position. Since the thread end portion at the clamping position or the release position is located at the side of the position of the sewing needle by the first angle or the second angle because it is at the position rotated by the second angle in the same direction as the angle. When sewing with the thread end clamped, it is possible to reliably prevent the thread end from being sewn by the stitches. Other effects similar to those of the second aspect are achieved.

  According to the invention of claim 5, the elastic member for urging the first thread clamping member toward the clamping position, and the engagement for locking the first thread clamping member at the clamping position against the urging force of the elastic member. An engaging member that rotates the first thread clamping member from the clamping position to the release position by engaging the second thread clamping member when the second thread clamping member rotates from the clamping position to the release position. Since the first thread clamping member is provided, the rotation of the first thread clamping member to a position other than the clamping position is suppressed by the urging force of the elastic member. Therefore, the first thread clamping member is held at the clamping position and the second thread clamping member rotated to the clamping position. The yarn end can be securely clamped with the first yarn clamping member.

  Furthermore, when the second thread clamping member is rotated from the clamping position to the release position, the first thread clamping member is engaged with an engagement member provided on the second thread clamping member to resist the biasing force of the elastic member. A large torque is required to rotate to the release position. However, a small and inexpensive stepping motor can be used because it can be rotated to the release position at once by the large driving force of the solenoid actuator without using a stepping motor. Can do. Other effects similar to those of the fourth aspect are achieved.

  According to the sixth aspect of the present invention, the pivot point of the first thread clamping member is provided on the base side in the length direction of the bed rather than the needle hole, and the pivot point of the second thread clamping member is the first thread clamping point. Since it is provided further on the base side than the rotation fulcrum of the member, the clamping part of the second thread clamping member rotated to the clamping position overlaps with the clamping part of the first thread clamping member already located at the clamping position, The yarn end can be securely clamped by these clamping portions. On the other hand, when the second thread clamping member rotates to the clamping position, the two clamping parts are displaced due to the difference in the pivoting fulcrum. Therefore, the thread end of the second thread clamping member is clamped by opening the thread hole of the second thread clamping member. Can be reliably released. Other effects similar to those of any one of claims 3 to 5 are achieved.

  According to the invention of claim 7, the enlarged portion is formed on the moving side to the first yarn clamping member at the tip portion having the yarn hole of the second yarn clamping member, and enlarged at least at the start position of the second yarn clamping member. Since a part of the portion is overlapped with the first thread clamping member, when the second thread clamping member rotates to the clamping position, the first thread clamping member overlaps with the first thread clamping member through the first thread clamping member. While maintaining a predetermined movement speed without colliding with the yarn clamping member, smooth movement to the clamping position can be realized, and the clamping operation can be speeded up. Other effects similar to those of any one of claims 1 to 6 can be achieved.

  According to the eighth aspect of the present invention, since the origin position of the second thread clamping member associated with the initial setting of the stepping motor is set to the start position, the second thread clamping is performed when the initial setting of the stepping motor is executed. Since the member rotates to the start position which is the origin position, the sewing can be started immediately at the start position, and interference between the sewing needle and the second thread clamping member can be reliably prevented. Other effects similar to those of any one of claims 1 to 7 can be achieved.

  According to the ninth aspect of the present invention, since the first detection sensor for detecting that the second thread clamping member is at the start position is provided, the first detection sensor rotates the second thread clamping member to the start position. Can be reliably detected, and the detection signal from the first detection sensor can be effectively utilized for the upper thread clamping control at the start of sewing. Other effects similar to those of any one of claims 1 to 8 can be achieved.

  The upper thread clamping mechanism of the sewing machine in the present embodiment includes a first thread clamping plate having a first thread clamping part and a second thread clamping plate having a second thread clamping part and a thread hole on the lower surface of the bed part, respectively. The second thread clamping plate is pivotally mounted, and the second thread clamping plate is clamped by the thread clamping motor, and the thread end is clamped in cooperation with the start position where the thread hole matches the needle hole of the needle plate and the first thread clamping plate. It is made to drive rotationally to a clamping position and a release position for releasing the clamping of the yarn end.

  As shown in FIG. 1, the electronic tacking sewing machine 1 is placed on a work table 8, and includes a bed portion 2, a pedestal portion 5 erected upward from a rear end portion of the bed portion 2, and a pedestal portion. 5 is composed of an arm portion 6 that extends forward from the upper end of 5 so as to face the bed portion 2.

  An operation panel 9 (see FIG. 10) is provided on the work table 8. The operation panel 9 includes a liquid crystal display, a selection switch for selecting the type of stitches to be used for sewing and a stitch pattern, and an upper thread. There are provided various types of switches and lamps for setting various sewing conditions such as a thread holding mode switch for setting whether or not to hold the end of the thread, sewing speed, and the like.

  A sewing machine motor 67 (see FIG. 10) for driving the sewing needle 11 up and down through the needle bar 10 and the driving force of the sewing machine motor 67 are transmitted to the sewing needle 11 through the main shaft. A driving force transmission mechanism, a presser drive mechanism (not shown) that moves the presser foot 13 up and down via a presser foot mechanism (not shown), and the like are provided, and the needle bar 10 is moved up and down inside the front end portion of the arm portion 6. A needle bar up-and-down moving mechanism to be moved, a balance driving mechanism for driving a balance for pulling up the upper thread, and the like are provided. However, since this is a known technique, detailed description thereof is omitted here.

  The bed portion 2 includes a bed main body portion 3 on which a pedestal column portion 5 is erected and a cylinder bed portion 4 extending forward from the bed main body portion 3, and a needle plate having a needle hole 12 a on the upper surface of the cylinder bed portion 4. 12 is detachably fixed.

  Although not shown in the figure, the bed portion 2 includes a sewing presser 11 in addition to a presser foot mechanism having a presser foot 13 and a cloth feed mechanism that moves the feed plate 14 in the front-rear direction (Y direction) and the left-right direction (X direction). A vertical hook (half-turn hook) 15 that forms a tack-stopping seam in time with the vertical movement, a lower shaft 16 that transmits a half-rotation driving force to the vertical hook 15, an upper thread clamping mechanism 20 to be described later, A thread trimming mechanism (not shown) that cuts the upper thread and the lower thread at the end of sewing is provided.

  As shown in FIG. 3, the vertical hook 15 is arranged in a front-facing manner, and a vertical hook 15a attached to the sewing machine frame, a rotary hook 15b rotatably supported by the big hook 15a, The driver 15c is composed of a driver 15c and the like, and the driver 15c is driven by the lower shaft 16 by half rotation. A bobbin case 17 is accommodated in the inner hook 15b, and a sword tip 15d is formed.

  Here, a foot pedal 18 (see FIG. 10) is provided on the lower side of the work table 8, and when the operator depresses to the first presser position, the presser motor 68 is driven through the presser foot mechanism. Sewing control is started when the presser foot 13 is lowered from the raised position to the lowered position (pressed position) on the top surface of the needle plate 12 and is depressed to the second stage sewing position by the operator.

  Next, the upper thread clamping mechanism 20 provided in the bed part 2 will be described. The upper thread clamping mechanism 20 includes a first thread clamping plate 21 (which corresponds to the first thread clamping member) pivoted on the lower surface of the needle plate 12 and a second thread clamping plate 22 (which corresponds to the second thread clamping member). And a rotation drive mechanism 35 (which corresponds to the drive means) for driving the first and second thread clamping plates 21 and 22 to rotate.

  As shown in FIGS. 2 to 5, on the lower surface of the needle plate 12, the proximal end portion of the substantially L-shaped first thread clamping plate 21 is vertically rearward and leftward from the needle hole 12 a. A pin 23 (which corresponds to a pin member) is pivotally mounted so as to be rotatable. A first thread clamping portion 21b is formed at the front end of the clamping arm portion 21a of the first thread clamping plate 21, and a stopper portion 21d (this corresponds to a locking member) on the spring receiving portion 21c of the first thread clamping plate 21. ) Are integrally formed so as to protrude rearward.

  Further, on the lower surface of the needle plate 12, a base end portion of a substantially L-shaped second thread clamping plate 22 disposed below the first thread clamping plate 21 is located behind and behind the needle hole 12a. On the rear side (the base side in the length direction of the bed portion 2) of the rotation support point of the single thread clamping plate 21, it is pivotally attached by a vertical second pivot pin 24 (this corresponds to a pin member). ing. That is, the first thread clamping plate 21 is disposed on the lower surface of the needle plate 12, and the second thread clamping plate 22 is disposed immediately below the first thread clamping plate 21.

  A thread hole 22b that allows the sewing needle 11 and the upper thread 7 to pass therethrough is formed at the distal end of the gripping arm part 22a of the second thread clamping plate 22, and the second thread clamping part 22c is formed at the front end portion adjacent to the thread hole 22b. Is formed. An enlarged portion 22g is formed on the moving side (left side) to the first yarn clamping plate 21 in the second yarn clamping portion 22c in which the yarn hole 22b is formed. As shown in FIG. 4, when the second thread clamping plate 22 is located at the start position 22 (S), a part of the enlarged portion 22 g of the first thread clamping plate 21 is formed as shown in FIG. 5. It superposes | stacks on the 1st thread clamping part 21b from the lower side.

  A spring locking plate 25 is fixed to the rear end portion of the needle plate 12, and a tension coil spring 26 is hung between the spring locking plate 25 and the tip of the spring receiving portion 21c of the first thread clamping plate 21. Yes. Therefore, the first thread clamping plate 21 is elastically biased counterclockwise in a plan view by the spring force of the tension coil spring 26, that is, toward the clamping position 21 (K), but the stopper portion 21d is Abutting on an upward boss portion 22d formed at the base end portion of the second thread clamping plate 22 is locked at a clamping position 21 (K) shown in FIG.

  Here, the connecting portion of the connecting arm portion 22e of the second thread clamping plate 22 is disposed on the upper side of the connecting portion, which is the tip of a thread clamping linkage 45 of the rotation drive mechanism 35 described later, and is located on the upper side. An engagement hole 22f is formed in the connecting portion of the two-thread holding plate 22, and an upward connecting pin 46 is fixed to the connecting portion of the thread-holding linkage 45 located on the lower side. Therefore, the coupling pin 46 is fitted into the engagement hole 22f so that the connection can be released from the lower side, and the second thread clamping plate 22 and the thread clamping linkage 45 engage the coupling pin 46 and the engagement hole 22f. It is connected so that rotation is possible.

  Further, an engagement pin 27 (which corresponds to an engagement member) is fixed to the upper surface from the rear side of the thread hole 22b of the sandwiching arm portion 22a of the second thread sandwiching plate 22, and the second thread sandwiching plate 22 is shown in FIG. 6 is rotated from the clamping position 22 (K) shown in FIG. 6 to the release position (L) shown in FIG. 8, the engaging pin 27 engages with the clamping arm portion 21 a of the first thread clamping plate 21. The thread clamping plate 21 rotates from the clamping position 21 (K) shown in FIG. 6 to the release position 21 (L) shown in FIG. 8 against the spring force of the tension coil spring 26.

  Here, a fixed blade 30 having a blade portion is screwed to the lower surface of the needle plate 12, and a movable blade 31 having a blade portion is pivotally attached by a pivot pin 32. The rotary blade 0 is connected to the tip of the thread trimming linkage 33, and the thread trimming linkage 3 is moved forward via the thread trimming drive system by driving the thread trimming solenoid 69 when the thread is cut. The upper thread 7 and the lower thread are cut in cooperation with the fixed blade 30 and the details thereof are omitted.

  Next, the second thread clamping plate 22 is rotated through the thread clamping linkage 45 over the start position 22 (S), the clamping position 22 (K), and the release position 22 (L). The drive mechanism 35 is demonstrated based on FIG.1, FIG.2, FIG.4.

  A thread clamping motor 36 composed of a stepping motor is disposed downward on the bed main body 3 and is fixed to the frame via an attachment plate 37. The base end portion of the drive lever 38 is fixed to the drive shaft 36 a of the yarn clamping motor 36, and the base end portion of the L-shaped link plate 39 is connected to the tip end portion of the drive lever 38 by a connecting bolt 40. A rotation lever 41 having upper and lower connecting arm portions 41a and 41b is disposed on the side of the thread clamping motor 36, and is pivotally supported on the frame via a vertically-supported pivot shaft 42.

  The other end portion of the link plate 39 is connected to the lower connecting arm portion 41a of the rotating lever 41 by a connecting bolt 43, and one end portion of the thread clamping linkage 45 is connected to the upper connecting arm portion 41b of the rotating lever 41. They are connected by connecting bolts 44. A connecting pin 46 fixed to the upper surface of the tip end portion of the yarn clamping linkage 45 is fitted into the engaging hole 22f of the connecting arm portion 22e of the second yarn clamping plate 22 from below.

  On the other hand, an extension 45a is formed behind one end of the yarn clamping linkage 45, and a yarn release solenoid 49 is provided immediately behind the extension 45a. A slit having a width larger than the plate thickness of the yarn clamping linkage 45 is formed over a predetermined length at the tip of the plunger 45a of the yarn release solenoid 49, and the extension 45a is connected by a pin 49b in the slit. Yes.

  Here, as shown in FIG. 2, when the yarn release solenoid 49 is not driven and the plunger 49a is in the advanced state, the second yarn clamping plate 22 is at the start position 2 (S), and the yarn release is performed. When the solenoid 49 is driven and the plunger 49a is driven to retract, the second thread clamping plate 22 rotates at once to the release position 22 (L) via the clamping position 22 (K). Of course, even when the yarn release solenoid 49 is driven when the second yarn clamping plate 22 is at the clamping position 22 (K), the second yarn clamping plate 22 rotates to the release position 22 (L).

  The origin position of the second thread clamping plate 22 accompanying the initial setting of the thread clamping motor 36 is set to the start position 22 (S) shown in FIG. However, the start position 2 (S) of the second thread clamping plate 22 is the origin position at the time of initial setting of the thread clamping motor 36, and the thread hole 22b matches the needle hole 12a of the needle plate 12. This is the position where the sewing needle 11 and the thread end 7a can be inserted.

  Therefore, by driving a predetermined amount of the yarn clamping motor 36, the second yarn clamping plate 22 corresponds to the first angle from the start position 22 (S) in FIG. 4 to the clamping position 22 (K) shown in FIG. Rotate clockwise by α1. At this time, since the first thread clamping plate 21 is at the clamping position 21 (K), the second thread clamping part 22c of the second thread clamping plate 22 moved to the clamping position 22 (K) and the clamping position 21 (K). The thread end portion 7a extending from the eye hole 11a of the sewing needle 11 is clamped by the cooperation with the first thread clamping portion 21b of the first thread clamping plate 21 in the above.

  By driving the thread release solenoid 49, the second thread clamping plate 22 rotates clockwise by α2 corresponding to the second angle from the clamping position 22 (K) in FIG. 6 to the release position 22 (L) shown in FIG. Move. At this time, the engagement pin 27 of the second thread clamping plate 22 is engaged with the clamping arm portion 21a of the first thread clamping plate 21, and the first thread clamping plate 21 is clamped in FIG. It is rotated from the position 21 (K) to the release position 21 (L) shown in FIG.

  In this case, the distance from the rotation fulcrum of the second thread clamping plate 22 to the second thread clamping part 22c is larger than the distance from the rotation fulcrum of the first thread clamping plate 21 to the first thread clamping part 21b. In addition, since the engaging pin 27 engages with the holding arm portion 21a on the rotation fulcrum side with respect to the first yarn holding portion 21b of the first yarn holding plate 21, the first yarn holding portion of the first yarn holding plate 21 is engaged. Since 21b rotates more largely than the second thread clamping portion 22c of the second thread clamping plate 22, the thread hole 22b of the second thread clamping plate 22 has a first thread clamping portion 21b as shown in FIG. The yarn end portion 7a that has been nipped is released without being blocked by the opening.

  Incidentally, an origin detection sensor 48 (which corresponds to a first detection sensor) including a magnetic sensor (so-called proximity sensor) is provided between the detection arm portion 39a of the link plate 39 and the mounting plate 37. This origin detection sensor 48 detects the detection arm portion 39a of the link plate 39 when the second yarn clamping plate 22 is rotated to the start position 22 (S) by the driving of the yarn clamping motor 36. The level origin position detection signal is output. That is, when the origin position detection signal from the origin detection sensor 48 is at “H” level, the second thread clamping plate 22 is rotated to the start position 22 (S).

  Next, a control system of the electronic tacking sewing machine 1 will be described. As shown in FIG. 10, the control device 55 includes a computer including an input interface 56, a CPU 57, a ROM 58, a RAM 59, an output interface 60, drive circuits 61 to 66, and the like. The input interface 66 is connected to the first switch 18a and the second switch 18b of the foot pedal 18, the operation panel 9, the origin detection sensor 48, and the like.

  From the output interface 60 to the sewing machine motor 67 via the drive circuit 61, to the presser motor 68 via the drive circuit 62, to the thread clamping motor 36 via the drive circuit 63, and to the thread release solenoid 49 via the drive circuit 64. , The yarn feed solenoid 69 via the drive circuit 65, the X axis drive motor 70 for moving the cloth feed mechanism in the left-right direction (X direction) via the drive circuit 66a, and the cloth feed mechanism via the drive circuit 66b. A drive signal is output to each Y-axis drive motor 71 that moves in the direction (Y direction).

  The first switch 18a is turned on when the operator depresses the foot pedal 18 to the first presser foot position, and lowers the presser foot 13 from the raised position to the lowered position (pressed position) on the upper surface of the needle plate 12. . The second switch 18b is turned on when the foot pedal 18 is depressed to the second sewing position by the operator, and sewing control is started. The ROM 58 stores sewing data for various tacking stitches, and stores in advance a control program for sewing control for forming tacking stitches to be described later.

  Next, the sewing control executed by the control device 55 will be described based on the flowchart of FIG. In the figure, symbol Si (i = 11, 12, 13...) Indicates each step. However, when the power is turned on, the thread clamping motor 36 is rotated counterclockwise by a predetermined amount in plan view by the initial setting control, and the origin position of the second thread clamping plate 22 by a locking member (not shown). That is, the start position 22 (S) is determined.

  When the work cloth W to be sewn is placed on the needle plate 12 and the foot pedal 18 is depressed to the first presser position, the presser foot 68 is driven by the presser motor 68 based on the ON signal of the first switch 18a. The work cloth W is pressed by moving to the lowered position. Next, this control is started when the foot pedal 18 is depressed to the second stage sewing position.

  This control is started. First, when the second switch 18b is ON (S11: Yes) and the thread clamping mode switch of the operation panel 9 is ON, that is, when the thread end 7a is clamped ( S12: Yes), the yarn clamping motor 36 is driven by the origin detection control, and the second yarn clamping plate 22 is rotated to the start position 22 (S) (S13). Next, when the origin position detection signal from the origin detection sensor 48 is at the “H” level (S14: Yes), the sewing machine motor 67 is driven (S15), and the sewing process for the stitches selected in advance is performed. It starts (S16).

  By the way, when the origin position detection signal from the origin detection sensor 48 is “L” level (S14: No), since the position of the second thread clamping plate 22 is abnormal, an error message is displayed on the display of the operation panel 9. Error processing such as display is executed (S26), and this control is terminated.

  Next, when the sewing process is started and the first sewing needle 11 reaches the thread clamping timing above the needle plate 12, that is, in FIG. 12, the phase angle of the main shaft is in the range of about 360 ° to 30 °. In this case (S17: Yes), by driving the thread clamping motor 36, the second thread clamping plate 22 is rotated by α1 and rotated to the clamping position 22 (K) (S18).

  At this time, when the origin position detection signal of the origin detection sensor 48 is “L” level (S19: Yes), the second thread clamping plate 22 is normally rotated to the clamping position 22 (K). When the detection signal is not at the “L” level (S19: No), since it is abnormal, the drive of the sewing machine motor 67 is immediately stopped (S25), error processing is executed (S26), and this control is terminated.

  Next, when the stitch formation of a predetermined number of stitches (for example, three stitches) is completed by the sewing process (S20: Yes), it is not necessary to clamp the thread end 7a. While the power supply is stopped for a predetermined time, the thread release solenoid 49 is driven for a predetermined time (for example, about 1 second), and the second thread clamping plate 22 is further rotated by α2 to release the release position 22 (L ) (S21). In this case, since the second thread clamping plate 22 is reliably rotated to the release position 22 (L) by driving the thread release solenoid 49, the sewing process is continued.

  When the sewing process of the tacking seam is completed (S22: Yes), the movable blade 31 is driven via the thread trimming mechanism by driving the thread trimming solenoid 69, and the upper thread 7 and the lower thread are cut (S23). ). Next, the thread clamping motor 36 is driven in the reverse direction, and the second thread clamping plate 22 is rotated back to the start position 22 (S) at once (S24).

  By the way, when the yarn clamping mode switch is OFF and the yarn clamping is not performed (S12: No), the yarn release solenoid 49 is turned on while the power supply to the yarn clamping motor 36 is stopped for a predetermined time. Driven for a predetermined time, the second thread clamping plate 22 is rotated to the release position 22 (L) at a stroke via the clamping position 22 (K) (S27). Next, the sewing machine motor 67 is driven (S28), the sewing process is executed (S29), the thread trimming process is executed along with the end of the sewing process (S30), and this control is finished.

  Next, the operation and effect of the electronic tacking sewing machine 1 configured as described above will be described with reference to FIG.

  When the foot pedal 18 is depressed to the second sewing position, the second thread clamping plate 22 rotates to the start position 22 (S) shown in FIG. 4, so that the sewing needle 11 and the thread end 7a are accompanied with the start of sewing. Enters the needle hole 12a and the thread hole 22b. Then, the upper thread 7 is engaged with the sword tip 15d of the vertical hook 15, and the upper thread loop is expanded by the movement of the sword point 15d.

  When the first sewing needle 11 moves to the upper side of the needle plate 12 and the phase angle of the main shaft is about 360 ° to 30 °, that is, the upper thread 7 is tightened to some extent by the balance, and the length of the thread end 7a is about When the length is shortened to 2 to 3 cm, and at the time of thread clamping, the second thread clamping plate 22 is clamped by α1 corresponding to the first angle when the thread clamping motor 36 is driven by a predetermined amount. ) (See FIGS. 6 and 7), the yarn end portion 7a is securely clamped between the first clamping portion 21b of the first yarn clamping plate 21 and the second clamping portion 22c of the second yarn clamping plate 22. Then, the sewing process is continued.

  When the sewing process is continued with the yarn end portion 7a being clamped by the cooperation of the first and second yarn clamping portions 21b and 22c, the clamping position 21 by the first and second yarn clamping portions 21b and 22c. Since (K) and 22 (K) are located to the side of the position of the sewing needle 11, it is possible to reliably prevent the thread end 7a from being caught on the seam by being caught by the sword tip 15d during sewing. Can do.

  After that, when the sewing process proceeds and, for example, “3 stitches” stitches are formed, the thread release solenoid 49 is set to a predetermined value while the power supply to the thread clamping motor 36 is stopped for a predetermined time. It is driven for a time (for example, about 1 second), and the second thread clamping plate 22 is rotated to the release position 22 (L) by α2 corresponding to the second angle.

  At the same time, the first thread clamping plate 21 is also rotated to the release position 21 (L) through the engagement of the engagement pin 27 (see FIGS. 8 and 9). In this case, as described above, the thread hole 22b of the second thread clamping plate 22 is based on the fact that the rotation fulcrum of the first and second thread clamping plates 21 and 22 is shifted and the engagement position of the engagement pin 27. Is opened, the yarn end 7a can be reliably opened.

  By the way, the second thread clamping plate 22 and the thread clamping linkage 45 are provided with an upward connecting pin 46 at the tip of the thread clamping linkage 45 in the engagement hole 22f of the coupling arm portion 22e of the second thread clamping plate 22. Since it is only fitted from the lower side, that is, the connecting portion between the second thread clamping plate 22 and the thread clamping linkage 45 is configured to be disengaged, so that the thread dust adhered to the lower side of the needle plate 12 When the needle plate 12 is removed to clean the needle plate 12 and the like, the plurality of set screws fixing the needle plate 12 are removed, and the needle plate 12 is lifted upward, so that the engagement hole of the second thread clamping plate 22 is removed. The engagement of the connecting pin 46 of 22f and the thread clamping linkage 45 is easily released, and the needle plate 12 can be easily removed.

  As described above, the first thread clamping plate 21 and the second thread clamping plate 22 are arranged on the lower surface of the needle plate 12, and the first thread clamping plate 21 is pivotally attached to the first pivot pin 23 so as to be rotatable. The second thread clamping plate 22 is pivotally attached by the second pivot pin 24, and the second thread clamping plate 22 is rotated by the thread clamping motor 36 from the start position 22 (S) to the clamping position 22 (K). Since it is driven, sewing is started when the second thread clamping plate 22 is rotated to the start position 22 (S), and when the first stitching needle after the start is moved to the upper side of the needle plate, the second thread Since the clamping plate 22 is rotated to the clamping position 22 (K), the yarn end portion 7a can be reliably clamped by the cooperation of the second yarn clamping plate 2 and the first yarn clamping plate 21.

  On the other hand, when the sewing for several stitches is executed, the second thread clamping plate 22 is rotated to the release position 22 (L) by the thread release solenoid 49 and the clamping of the thread end 7a is released, so that the sewing starts. It is possible to reliably prevent skipping over time. In addition, since the second thread clamping plate 22 is merely rotated from the start position 22 (S) to the clamping position 22 (K) and further from the clamping position 22 (K) to the release position 22 (L), the upper thread clamping mechanism 20 Thus, the size and weight of the sewing machine can be reduced, and the cost can be reduced.

  Further, when the second thread clamping plate 22 is rotated from the clamping position 22 (K) to the release position 22 (L), the first thread clamping plate 21 is engaged with the engagement pin 27 provided on the second thread clamping plate 22. In combination, a large torque is required to rotate to the release position 22 (L) against the spring force of the tension coil spring 26, but without using a thread clamping motor, the large force of the thread release solenoid 49 can be used at once. A small and inexpensive thread clamping motor that can be rotated to the release position 22 (L) can be used.

  Further, the rotation support point of the second thread clamping plate 22 is shifted to the back side with respect to the rotation support point of the first thread clamping plate 21, and the first thread clamping by the engagement pin 27 of the second thread clamping plate 22. Since the engagement position of the plate 21 is set between the first clamping portion 21b and the rotation fulcrum, the clamping of the yarn end portion 7a is realized, so that the upper yarn clamping mechanism 20 is further simplified and reduced in size. be able to.

  Further, since the origin position of the second thread clamping member 22 associated with the initial setting of the thread clamping motor 36 is set to the start position 22 (K), when the initial setting of the thread clamping motor 36 is executed, the second thread is held. Since the clamping member 22 rotates to the origin position which is the start position 22 (K), sewing can be started immediately at the rotation position, and the interference between the sewing needle 11 and the second thread clamping member 22 is ensured. Can be prevented.

  Further, an enlarged portion 22g is formed on the moving side of the second holding portion 22c having the yarn hole 22b of the second yarn holding plate 22 to the first yarn holding plate 21, and a part of the enlarged portion 22g is the second yarn holding plate. 22 at least at the start position 22 (S), the first thread clamping plate 21 is superposed from the lower side. Therefore, when the second thread clamping plate 22 rotates to the clamping position 22 (K), the enlarged portion 22g Through superposition with the first yarn clamping plate 21, it is possible to realize a smooth movement to the clamping position 22 (K) while maintaining a predetermined movement speed without colliding with the first yarn clamping plate 21. It is possible to speed up the clamping operation.

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

  1) When the drive of the thread release solenoid 49 is stopped, the plunger 49a is configured to return to the advanced state by the spring force of a coil spring (not shown), and as shown in FIG. , The second thread clamping plate 22 is rotated from the starting position 22 (S) to the clamping position 22 (K), and the second thread clamping plate 22 is moved by the retracting drive of the thread release solenoid 49. To the release position 22 (L).

  With the end of the sewing process, the driving of the thread release solenoid 49 is stopped, the plunger 49a of the thread release solenoid 49 is advanced by the spring force of the coil spring, and the second thread clamping plate 22 is temporarily held at the clamping position 22 (K ) And the second thread clamping plate 22 may be returned to the start position 22 (S) by the reverse rotation driving of the thread clamping motor 36.

  2] The first thread clamping plate 21 is fixed to the lower surface of the needle plate 12, and the second thread clamping plate 22 is rotated from the start position 22 (S) to the release position 22 (L) through the clamping position 22 (K). When moved, the yarn hole 22b may be released by passing through the first yarn clamping plate 21, and the yarn end portion 7a may be released.

  3] The rotation direction of the second thread clamping plate 22 and the arrangement of the first thread clamping plate 21 are opposite to those in FIG. 4, and the second thread clamping plate 22 is rotated counterclockwise in plan view. Thus, the clamping position 22 (K) and the release position 22 (L) may be realized.

  4) Various electric actuators such as a DC motor capable of feedback control, a linear solenoid, and a linear solenoid instead of the thread release solenoid 49 may be used instead of the thread clamping motor 36. Good.

  5] The vertical hook 15 is not limited to a half rotary hook, but may be a full rotary hook.

  6] The shape of the thread hole is not limited to a circle, and may be various shapes such as an ellipse that is long on the left and right, a rectangle, and a polygon.

  7) A release detection sensor for detecting the release position 22 (L) of the second thread clamping plate 22 via the thread clamping linkage 45 is provided, and based on the release position 22 (L) detection signal output from the release detection sensor. Thus, the release position 22 (L) of the second thread clamping plate 22 may be configured to be detectable.

  8) The second thread clamping plate 22 may be configured to be switched to the start position 22 (S), the clamping position 22 (K), and the release position 22 (L) by moving linearly.

  9] The present invention is not limited to the above-described embodiments, 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.

  10] Of course, the present invention can be applied to various types of sewing machines having various upper thread clamping mechanisms having first and second thread clamping members attached to the lower side of the needle plate.

It is a side view of the electronic tacking sewing machine concerning the example of the present invention. It is a perspective view of an upper thread clamping mechanism. It is a front view of a bed part. It is a fragmentary top view of the cylinder bed part explaining a starting position. It is the EE line vertical front view of FIG. It is a fragmentary top view of the cylinder bed part explaining a clamping position. It is the GG line vertical front view of FIG. It is a partial top view of a cylinder bed part explaining a release position. It is the II sectional view front view of the II line | wire of FIG. It is a block diagram of the control system of an electronic tacking sewing machine. It is a flowchart of sewing control. It is a figure which shows the movement locus | trajectory of a balance and a needle bar with respect to the phase angle of a main axis | shaft. It is explanatory drawing about the rotation position of the 2nd thread clamping board by a thread clamping motor and a thread release solenoid. FIG. 14 is a diagram corresponding to FIG. 13 according to a modified embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic bar clamp sewing machine 2 Bed part 7a Thread end part 12 Needle plate 12a Needle hole 20 Upper thread clamping mechanism 21 First thread clamping board 21b First clamping part 21d Stopper part 22 Second thread clamping plate 22b Yarn hole 22c Second clamping Part 22f Engagement hole 22g Enlarged part 23 First pivot pin 24 Second pivot pin 26 Pulling coil spring 27 Connecting pin 35 Rotation drive mechanism 36 Thread clamping motor 45 Thread clamping linkage 48 Origin detection sensor 49 Thread release solenoid

Claims (9)

In the upper thread clamping mechanism of the sewing machine that releasably clamps the thread end of the upper thread extending from the stitch hole of the sewing needle under the needle plate of the bed part,
A first thread clamping member attached to the lower surface of the needle plate;
A second thread pinching member that has a thread hole that allows a sewing needle to pass through the needle hole of the needle plate and that clamps the thread end in cooperation with the first thread gripping member;
Driving means for moving the second yarn clamping member across a start position for starting clamping of the yarn end portion, a clamping position for clamping the yarn end portion, and a release position for releasing the clamping of the yarn end portion; With
The driving means includes a stepping motor capable of executing movement from the start position to the clamping position and at least a solenoid actuator used for movement from the clamping position to the release position. Pinching mechanism.   2. The upper thread clamping mechanism according to claim 1, wherein the driving unit rotationally drives the second thread clamping member across the start position, the clamping position, and the release position.   The first thread clamping member is pivotally attached to the needle plate by a vertical pin member, and a clamping position for clamping the thread end portion in cooperation with the second thread clamping member; and the thread end The upper thread clamping mechanism of the sewing machine according to claim 2, wherein the upper thread clamping mechanism of the sewing machine is configured to be rotatable over a release position where the clamping of the portion is released.   The clamping position is at a position where the second thread clamping member is rotated by a first angle with respect to the start position, and the release position is in the same direction as the first angle with respect to the clamping position. The upper thread holding mechanism of the sewing machine according to claim 2, wherein the upper thread holding mechanism is at a position rotated by a second angle.   An elastic member for urging the first thread clamping member toward the clamping position; and a locking member for locking the first thread clamping member at the clamping position against the urging force of the elastic member; An engagement member that rotates the first thread clamping member from the clamping position to the release position by engagement when the thread clamping member rotates from the clamping position to the release position is provided in the second thread clamping member. The upper thread clamping mechanism of the sewing machine according to claim 4.   The rotation support point of the first thread holding member is provided on the base side in the length direction of the bed rather than the needle hole, and the rotation support point of the second thread holding member is further than the rotation support point of the first thread holding member. The upper thread clamping mechanism of the sewing machine according to any one of claims 3 to 5, wherein the upper thread clamping mechanism is provided on a base side.   An enlarged portion is formed on the moving side to the first yarn clamping member at the tip end portion having the yarn hole of the second yarn clamping member, and a part of the enlarged portion is at least at the start position of the second yarn clamping member. The upper thread clamping mechanism according to any one of claims 1 to 6, wherein the upper thread clamping mechanism is superposed on a single thread clamping member.   The upper thread pinching mechanism of the sewing machine according to any one of claims 1 to 7, wherein an origin position of the second thread clamping member according to an initial setting of the stepping motor is set to the start position. The upper thread clamping mechanism according to any one of claims 1 to 8, further comprising a first detection sensor that detects that the second thread clamping member is at a start position.