JP4232096B2 - Needle thread guide structure of multi-needle sewing machine - Google Patents

Description

  According to the present invention, when moving a needle bar case on which a plurality of needle bars are mounted, the upper thread portion extending from the sewing needle mounted on each needle bar to the thread holding portion is not caught by the threading guide of the threading mechanism. Further, the present invention relates to an upper thread guide structure for guiding the upper thread portion.

  Conventionally, there has been proposed a sewing machine including a threading means that can automatically thread a sewing needle. For example, in Patent Document 1, in a state where a thread is guided by a thread guide groove or the like and held by a thread holding portion or the like, the thread is captured by a threading hook that is inserted into the eye of a sewing needle, and the threading hook is used. A technique is described in which a thread is passed through an eye by pulling out the eye from the eye.

  Further, Patent Document 2 includes needle bar support means (needle bar support case) that supports a plurality of needle bars, and by moving the needle bar support means, a desired needle bar (sewing needle) is brought into a use position. It describes the technology to move, and after the thread trimming operation at the end of sewing, etc., and the technology to wipe the end of the cut thread from the cloth and guide it with the thread clamp and grip the thread end with the thread clamp. Yes.

JP-A-8-173676 (pages 3-6, FIGS. 1-6) JP-A-6-254279 (pages 3 to 5, FIGS. 1 to 3)

  However, the threading device of Patent Document 1 is a threading device intended to thread a single sewing needle, and it is practical to apply this technique to a multi-needle sewing machine having a plurality of needle bars. It is not a thing. That is, in a multi-needle sewing machine, since a plurality of needle bars are adjacent to each other, when each of the plurality of needle bars is provided with a threading hook advancing and retracting mechanism as in Patent Document 1, needles that support the plurality of needle bars are provided. Since the bar support means (needle bar support case) is increased in size and the number of parts is increased by providing the number of advance / retreat mechanisms corresponding to the number of needle bars, the technique described in Patent Document 1 is applied to a multi-needle sewing machine. It was impossible to do.

  Therefore, a single threading device having a threading hook and a threading hook advancing / retreating mechanism is provided, and needle bar support means (needle bar support case) for supporting a plurality of needle bars is relative to the threading device. It is conceivable to perform threading by moving the needle bar on which the sewing needle to be threaded is attached to the threading hook.

  However, in the multi-needle sewing machine, as described in Patent Document 2, a thread passed through a sewing needle that is not used for sewing does not fall out of the eye of the sewing needle or hang down on the work cloth. In addition, the thread end of the thread that has passed through the eye hole is held by the thread clamp. On the other hand, since the threading hook of the threading device needs to be able to penetrate and detach from the eye of the sewing needle, it is necessary to dispose the threading hook close to the sewing needle. A threading hook advancing / retreating mechanism for advancing / retreating (penetrating / removing) is also required to be disposed close to the sewing needle.

  In order to select a sewing needle used for sewing or a sewing needle for threading from among a plurality of sewing needles, it is necessary to move the needle bar support means. During this movement, the thread extending from the eye of the sewing needle extends. There is a possibility that the thread held by the grip will be caught by the threading hook advance / retreat mechanism and the thread end may come off the thread grip.

  In order to cope with this problem, it may be possible to arrange the threading hook advance / retreat mechanism sufficiently away from the sewing needle, but this makes it difficult to correctly advance and retract the threading hook into the eye of the sewing needle. It is necessary to increase the accuracy of parts of the threading hook advancing / retreating mechanism and the threading hook for correctly moving the threading hook back and forth in the eye hole.

  An object of the present invention is to perform threading with a threading mechanism reliably in a multi-needle sewing machine having a needle bar case to which a plurality of needle bars are mounted and a thread holding part that holds a thread end of an upper thread extending from a sewing needle. When moving the needle bar case, it is possible to reliably prevent the thread extending from each sewing needle to the thread holding section from being caught by the threading guide of the threading mechanism and the thread end from coming off the thread holding section. Providing an upper thread guide structure.

  In the needle thread guide structure of the multi-needle sewing machine according to claim 1, the needle bar case to which a plurality of needle bars are mounted and the needle bar case is moved so that any one of the plurality of needle bars is selectively used. Needle bar switching mechanism for switching, threading mechanism for passing the upper thread through the eye of the sewing needle mounted on the needle bar at the use position, and thread holding for retaining the thread end of the upper thread extending from each sewing needle behind the sewing needle The threading mechanism includes a threading hook that can be penetrated from the rear side into the eye of the sewing needle in the use position, and a threading hook that is provided on the rear side of the sewing needle and is in the retracted position. A threading guide that is switchably guided over a protruding position penetrating the stitch hole of the sewing needle, and provided with a thread avoiding portion having at least a convex spherical surface on the front end portion of the threading guide, When moving the needle bar case with the bar switching mechanism, it extends from each sewing needle to the thread holder. It is characterized in that the upper thread portion configured to guide by the yarn avoiding unit.

  A plurality of sewing needles are attached to the plurality of needle bars attached to the needle bar case, and upper threads extending from upper thread supply sources such as a plurality of thread spools are passed through the plurality of sewing needles, respectively. The needle bar case is moved by the needle bar switching mechanism, and one of the plurality of needle bars is selectively switched to the use position. The thread end of the upper thread extending from each sewing needle is held by the thread holding portion on the rear side of the sewing needle so that the upper thread does not come off from the eye hole of each sewing needle other than the sewing needle in use.

  In the threading mechanism, a threading guide is provided on the rear side of the sewing needle, and a threading hook is guided by the threading guide so as to be switched between a retracted position and a protruding position penetrating through the stitch hole of the sewing needle. . When the threading hook is switched to the protruding position, the needle threaded through the sewing needle at the use position, and when the threading hook at the protruding position is switched to the retracted position, the upper thread is hooked and the upper thread is sewn to the sewing needle. The eye is passed through.

  Now, when the needle bar case is moved by the needle bar switching mechanism, even if there is a possibility that the upper thread part extending from each sewing needle to the thread holding part may be caught by the front end part of the threading guide, at least the front end part of the threading guide By providing a thread avoiding portion with a convex spherical surface on the upper surface, the upper thread portion extending from each sewing needle to the thread holding portion is guided by this thread avoiding portion, so that the upper thread portion is at the front end of the threading guide. The yarn end does not come off from the yarn holding portion due to being caught.

  The upper thread guide structure of the multi-needle sewing machine according to claim 2 is characterized in that, in the invention of claim 1, the thread avoidance portion is detachably attached to the threading guide. A thread avoidance portion can be easily provided at the front end of the threading guide of the threading mechanism.

  The upper thread guide structure of the multi-needle sewing machine of claim 3 is characterized in that, in the invention of claim 2, a fitting hole into which the front end portion of the threading guide is fitted is formed in the thread avoidance portion. Is. The front end portion of the threading guide is fitted into the fitting hole of the thread avoiding portion, and the thread avoiding portion is attached to the threading guide.

  An upper thread guide structure of a multi-needle sewing machine according to a fourth aspect is the invention according to the third aspect, wherein a guide pin fixed to the threading hook is slidably engaged with at least a front end portion of the threading guide. A mating groove is formed, and an engaging hook that engages with the engaging groove is formed in a portion facing the fitting hole inside the yarn avoiding portion. The engagement hook of the thread avoidance portion engages with the engagement groove of the threading guide, and the thread avoidance portion is attached to the threading guide.

  The upper needle guide structure of the multi-needle sewing machine according to claim 5 is the invention according to claim 4, wherein a protruding portion protruding forward is formed at a front end portion of the threading guide, and a fitting hole inside the yarn avoiding portion. An engagement hole for engaging with the protruding portion is formed in a portion facing the surface. The protruding part of the threading guide engages with the engagement hole of the thread avoiding part, and the thread avoiding part is attached to the threading guide.

  According to the upper thread guide structure of the multi-needle sewing machine according to claim 1, in particular, the front end portion of the threading guide of the threading mechanism is provided with a thread avoiding portion having at least a convex spherical surface, and the needle bar switching mechanism uses the needle bar case. Since the upper thread portion extending from each sewing needle to the thread holding portion is guided by the thread avoiding portion when the needle is moved, the threading guide of the threading guide that guides the threading hook is brought close to the sewing needle. Improves guideability and allows the threading hook to pass through the eye of the sewing needle at the position of use to enable threading. When moving the needle bar case with the needle bar switching mechanism, each sewing needle moves to the thread holding section. It is possible to reliably prevent the extending upper thread portion from being caught by the threading guide and the thread end of the upper thread from coming off the thread holding portion.

  According to the needle thread guide structure of the multi-needle sewing machine according to claim 2, since the thread avoidance portion is detachably attached to the threading guide, the thread avoidance portion can be easily attached to and detached from the front end portion of the threading guide of the threading mechanism. It becomes.

  According to the upper thread guide structure of the multi-needle sewing machine according to claim 3, since the fitting hole into which the front end portion of the threading guide is fitted is formed in the thread avoiding portion, the front end portion of the threading guide is formed as the thread avoiding portion. The thread avoiding portion can be easily attached to the threading guide.

  According to the upper thread guide structure of the multi-needle sewing machine according to claim 4, at least a front end portion of the threading guide is formed with an engaging groove in which a guide pin fixed to the threading hook is slidably engaged, Since the engagement hook that engages with the engagement groove is formed in the part facing the fitting hole inside the thread avoidance part, the engagement hook of the thread avoidance part is engaged with the engagement groove of the threading guide, The thread avoidance part can be securely attached to the threading guide so that it cannot be easily removed, and the engagement groove of the threading guide with which the guide pin engages is used effectively, simplifying the structure and manufacturing costs. Also advantageous.

  According to the upper thread guide structure of the multi-needle sewing machine according to claim 5, a projecting portion protruding forward is formed at the front end portion of the threading guide, and the projecting portion is projected at the portion facing the fitting hole inside the thread avoiding portion. Since the engagement hole that engages the part is formed, the protruding part of the threading guide is engaged with the engagement hole of the thread avoiding part, and the thread avoiding part is securely attached to the threading guide without rattling. Can do.

  The needle thread guide structure of the present embodiment is applied to a multi-needle sewing machine having a needle bar case, a needle bar switching mechanism, a threading mechanism, and a thread holding portion. A threading hook that can penetrate the eye hole from the rear side, and a threader that is provided on the rear side of the sewing needle and guides the threading hook so as to be switchable between a retracted position and a protruding position that penetrates the eye hole of the sewing needle. An upper thread extending from each sewing needle to the thread holding section when the needle bar switching mechanism is moved by the needle bar switching mechanism. The portion is configured to be guided by the yarn avoiding portion.

  As shown in FIG. 1, in this multi-needle sewing machine M, a leg portion 1 that supports the entire sewing machine is provided, and a leg column portion 2 is erected from the rear end portion of the leg portion 1, and The arm part 3 extends forward from the upper part. A needle bar case 4 with a synthetic resin cover is attached to the front side of the arm part, and a cylinder bed 5 extends from the lower part of the pedestal column part 2 to the lower side of the front needle bar case 4.

  As shown in FIGS. 1 and 2, the needle bar case 4 has six needle bars 10 mounted in a left and right row, a sewing needle 11 is mounted on the lower end of each needle bar 10, and the needle bar case Four balances 12 are attached to 4 in a left and right row. A synthetic resin thread tension frame 13 that is slightly inclined rearward and upward is fixed to the upper end of the needle bar case 4, and six thread tensioners 14 are provided on the thread tension frame 13. Six piece stands 15 are provided on the upper side of the arm section 3, and six yarn pieces (not shown) as thread supply sources are attached to these piece stands 15, and upper yarns T extending from the respective yarn pieces correspond to the pieces. It is hung on the thread tension device 14 and the balance 12 and supplied to the sewing needle 11.

  Here, the needle bar case 4 is driven to move in the left-right direction integrally with the thread tension frame 13 by a needle bar switching mechanism (not shown), whereby one of the six needle bars 10 and the balance 12 is driven. The needle bar 10 and the balance 12 are alternatively switched to the use position. When the sewing machine motor (not shown) is driven, the needle bar 10 and the balance 12 at the use position are driven up and down, and in cooperation with a rotary hook (not shown) provided inside the cylinder bed 5, the cylinder bed 5. A stitch is formed by the upper thread T and the lower thread on the work cloth disposed on the upper side of the thread.

  The work cloth to be used for sewing is held in a state of being stretched on an embroidery frame (not shown), and this embroidery frame is attached to the frame mounting base 16 and set. The frame mount 16 is driven to move in the left-right direction by a left-right drive mechanism (not shown) provided inside the movable case 17, and the front-rear drive mechanism (not shown) provided inside the leg portion 1. Is driven to move in the front-rear direction. In this way, the embroidery frame is driven to move back and forth and right and left together with the frame mount 16 to feed the work cloth. The multi-needle sewing machine M is provided with a liquid crystal display 18 for displaying various screens in order to operate / stop the multi-needle sewing machine M, select an embroidery pattern, and the like.

  2 to 8, the multi-needle sewing machine M includes a threading mechanism 20 for passing the upper thread T through the eye hole 11 a of the sewing needle 11 mounted on the needle bar 10 at the use position, and each sewing needle 11. A thread holding portion 35 that holds the thread end of the extending upper thread T on the rear side of the sewing needle 11, and a wiper mechanism 40 that hooks the upper thread T extending from the sewing needle 11 at the use position and holds the thread end on the thread holding portion 35. And a yarn avoiding cap 50 corresponding to a yarn avoiding portion whose upper surface is convex spherical is provided at the front end of the threading guide 28 of the threading mechanism 20.

  As shown in FIGS. 4, 5, 7, and 8, the threading mechanism 20 includes an output gear 21 a that is guided by the threading motor 21 and the sewing machine frame 19 so as to move up and down and is driven by the threading motor 21. A vertically elongated rack member 22 that meshes with each other, a spring member 23 that elastically urges the rack member 22 upward, a link member 24 whose upper end is pivotally connected to the lower end of the rack member 22, and the link member 24 A link block 26 rotatably connected to the lower end via a first guide pin 25, a second guide pin 27 fixed to the link block 26, and an engagement groove in which the guide pins 25, 27 are slidably engaged. The threading guide 28 formed with 28a, 28b, a pair of left and right threading members 29 fixed to the link block 26, and a pair of threading members 29 fixed to the sewing needle 11 at the use position. Threading pierceable from the rear side to the hole 11a and a hook 30 or the like.

  The threading guide 28 is fixedly provided on the sewing machine frame 19 on the rear side of the sewing needle 11. The threading guide 28 has an engagement groove 28a formed horizontally from the front end portion thereof, and the engagement groove 28b is engaged. The guide grooves 25a and 27b are slidably engaged with the engagement grooves 28a and 28b so as to be inclined rearward and continuously on the rear side of the joint groove 28a. The threading hook 30 together with the thread hooking member 29 is guided so as to be switchable between a retracted position (see FIG. 7) and a protruding position (see FIG. 4) penetrating the eye 11a of the sewing needle 11.

  Here, a threading cap 50 is attached to the tip of the threading guide 28, but the guide pin 27 is positioned forward as much as possible without interfering with the threading cap 50, and the threading hook 30. Is in the protruding position. Further, a protruding portion 28 c that protrudes forward is formed at the front end portion of the threading guide 28.

  When the threading needle 11 for threading is switched to the use position and the threading switch (not shown) is operated while the threading hook 30 is positioned at the retracted position in FIG. 7, the threading motor 21 is driven. Then, the rack member 22 moves downward, the thread hooking member 29 and the threading hook 30 move downward and forward, and change from the forward leaning posture inclined downward to the front to the horizontal posture, and switched to the protruding position. The threading hook 30 penetrates the sewing needle 11 and the pair of thread hooking members 29 protrudes forward of the sewing needle 11 so as to sandwich the sewing needle 11.

  Here, on the lower front side of the needle bar case 4, six blades 32 and six thread end holding portions 33 corresponding to the six sewing needles 11 are provided, and the thread hooking member 29 and the threading hook 30 protrude. In the state of switching to the position, the upper thread T on which the predetermined thread has been hooked is hung from the lower side on the pair of thread hooking members 29 on the front side of the sewing needle 11, and the upper thread portion on the downstream side of the upper thread T corresponds to the corresponding blade 32. And the yarn end of the upper yarn T is held by the yarn end holding portion 33.

  Thereafter, the threading motor 21 is driven, the rack member 22 moves upward, the threading hook 30 hooks the upper thread T and moves to the retracted position side, then comes out of the eye hole 11a of the sewing needle 11, and the upper thread T is passed through the eye hole 11a. Subsequently, the threading hook 30 moves to the retracted position side, but temporarily stops at the middle thread passing position (see FIG. 8), and the upper thread T hung on the threading hook 30 is wiped by the wiper mechanism 40. 44, and then moves to the retracted position.

  Next, the thread holding portion 35 is disposed on the rear side of the six sewing needles 11 at a position slightly higher than the portion where the engagement groove 28a of the upper thread guide 28 is formed, and is a pair elongated in the left-right direction. Velcro tapes (registered trademark), and these velcro tapes are provided facing each other. An L-shaped attachment frame 36 with a lower portion bent rearward is fixed to the lower side of the needle bar case 4, and a thread holding portion 35 is attached to the attachment frame 36. 35 can hold the end of the upper thread T.

  As shown in FIGS. 3 to 8, the wiper mechanism 40 has a drive motor 41, a sector gear member 42 that meshes with an output gear 41 a that is driven by the drive motor 41, and an upper end that can be rotated at the rear end of the sector gear member 42. A link member 43 that is pin-coupled to the web, a wiper coupling portion 44 that is pivotally coupled to the lower end of the link member 43, and a wiper 45 that is integrally formed with the wiper coupling portion 44 and that has a thread hook 45a at the tip. A wiper guide 46 is provided for guiding the wiper 45 so as to be switchable between a retracted position (see FIG. 4) and a protruding position (see FIG. 8).

  Here, a needle bar release mechanism 49 is provided for releasing the needle bar 10 in the use position from a state where it is interlocked with a needle bar vertical movement mechanism (not shown). The drive motor 41, the output gear 41a, and the sector gear member 42 are This is common to both the needle bar release mechanism 49 and the wiper mechanism 40. A detailed description of the needle bar release mechanism 49 will be omitted.

  The wiper mechanism 40 holds the thread end of the upper thread T passed through the eye hole 11a of the sewing needle 11 by the threading mechanism 20 in the thread holding part 35, and replaces the upper thread T after sewing (other needles). This is a mechanism for holding the yarn end of the upper yarn T cut by the yarn cutting mechanism (not shown) in the yarn holding portion 35 when the rod 10 is switched to the use position, and the operation is as follows. .

  First, when the thread holding mechanism 35 holds the thread end of the upper thread T that is passed through the eye hole 11a of the sewing needle 11 by the threading mechanism 20, as shown in FIG. In a state where the upper thread T is hooked and stopped at the thread passing position, the drive motor 41 is driven, and the wiper 45 moves from the retracted position to the protruding position through the pair of magic tapes of the thread holding portion 35. The thread hooking portion 45a of the wiper 45 hooks the upper thread portion Ta between the sewing needle 11 and the threading hook 30 and then passes the thread holding portion 35. The yarn end of the yarn T is held in contact with the yarn holding portion 35.

  Next, when exchanging the upper thread T after sewing, if the thread end of the upper thread T cut by the thread cutting mechanism is held by the thread holding portion 35, before cutting the upper thread T, The work cloth is fed, and the upper thread T extending from the sewing needle 11 to the work cloth is set to an appropriate position and posture where the upper thread T can be hooked by the thread hooking portion 45a of the wiper 45. Thereafter, the same operation as described above is performed.

  As shown in FIGS. 5 and 7 to 15, the front end portion of the threading guide 28 of the threading mechanism 20 is provided with a thread avoiding cap 50 made of a synthetic resin having a convex spherical upper surface. The upper thread guide structure is configured such that the upper thread portion Ta extending from each sewing needle 11 to the thread holding portion 35 is guided by the thread avoidance cap 50 when the needle bar case 4 is moved in the left-right direction by the needle bar switching mechanism. Has been.

  As shown in FIGS. 9 to 15, the thread avoidance cap 50 is detachably attached to the front end of the threading guide 28, and the thread avoidance cap 50 has a substantially horizontal bottom 51 and a convex spherical shape. A convex spherical surface 52 constituting the upper surface, a fitting hole 53 into which the front end portion of the threading guide 28 is fitted, a pair of left and right engaging hooks 54 and 55 engaged with the front end portion in the engaging groove 28a, threading An engagement hole 56 is formed in which the protruding portion 28c at the front end of the guide 28 is engaged in an internal fit.

  The bottom 51, the convex spherical portion 52, and the pair of engaging hooks 54, 55 are integrally formed. The upper surface of the convex spherical portion 52 is formed as a convex spherical surface that is about 1/4 of an elliptical spherical surface. The rear end face is the same vertical face. The fitting hole 53 is a hole whose rear side is open to the outside, and its wall is formed by a recess 51 a formed in the bottom 51, a recess 52 a formed in the convex spherical surface 52, and a pair of engagement hooks 54 and 55. Is formed.

  The pair of engagement hooks 54, 55 are formed in a portion facing the fitting hole 53 inside the yarn avoidance cap 50, and extend rearward from the left and right side portions of the engagement hole 56 in the convex spherical portion 52. A gap is formed between the pair of engaging hooks 54 and 55 and the convex spherical portions 52 on both left and right sides thereof, and the engaging hooks 54 and 55 can be elastically deformed left and right, respectively. The engagement hole 56 is a hole whose front side opens to the outside, and is formed in a portion facing the fitting hole 53 inside the yarn avoidance cap 50.

  When the threading cap 50 is attached to the tip of the threading guide 28, the tip of the threading guide 28 is fitted into the fitting hole 53 of the threading cap 50. At this time, first, the threading guide 28 hits the tapers 54a and 55a formed in the rear end inner portions of the pair of engagement hooks 54 and 55, whereby the pair of engagement hooks 54 and 55 are separated from each other. Elastically deform in the left-right direction.

  Subsequently, when the threading guide 28 is fitted into the threading cap 50, the pair of engaging hooks 54 and 55 are maintained in an elastically deformed state in the middle, and finally, the threading guide 28 is finally obtained. When the projecting portion 28c of the thread is engaged with the engagement hole 56, the front end portion of the engagement groove 28a of the threading guide 28 becomes the same longitudinal position as the rear end portions of the pair of engagement hooks 54, 55. The engagement hooks 54 and 55 are restored and engaged with the front end portion of the engagement groove 28 a, and the threading cap 50 is attached to the distal end portion of the threading guide 28. Thus, the threading cap 50 can be easily attached to the tip of the threading guide 28.

The operation and effect of the upper thread guide structure of the multi-needle sewing machine M will be described.
A plurality of sewing needles 11 are attached to the plurality of needle bars 10 attached to the needle bar case 4, and the plurality of sewing needles 11 have upper threads extending from upper thread supply sources such as a plurality of thread pieces to the eye holes 11a. T is passed through and supplied, and the needle bar case 4 is moved in the left-right direction by the needle bar switching mechanism, and one of the plurality of needle bars 10 is selectively switched to the use position. The thread ends of the upper threads T extending from the respective sewing needles 11 are arranged on the rear side of the sewing needles 11 by the thread holding portions 35 so that the upper threads T are not pulled out from the eye holes 11a of the respective sewing needles 11 other than the sewing needles 11 in use. Is retained.

  In the threading mechanism 20, a threading guide 28 is provided on the rear side of the sewing needle 22, and a threading hook 30 is guided by the threading guide 28, and a protruding position that penetrates the eye 11 a of the sewing needle 11. It can be switched over. When the threading hook 30 is switched to the projecting position, the threaded needle 11 penetrates the eye 11a of the sewing needle 11 at the use position, and when the threading hook 30 is switched from the projecting position to the retracted position, the upper thread T is hooked. The upper thread T is passed through the eye hole 11 a of the sewing needle 11.

  Now, when the needle bar case 4 is moved in the left-right direction by the needle bar switching mechanism, even when there is a possibility that the upper thread portion Ta extending from each sewing needle 11 to the thread holding portion 35 is caught on the front end portion of the threading guide 28, This can be avoided by providing a thread avoiding portion 50 having a convex spherical surface on the front end portion of the threading guide 28. That is, as shown in FIG. 16, when the needle bar case 4 moves in the left-right direction, the upper thread portion Ta extending from each sewing needle 11 to the thread holding portion 35 also moves in the left-right direction in this state, and this upper thread portion Ta Hits the convex spherical upper surface of the yarn avoidance cap 50, and the upper thread portion Ta is guided upward by the convex spherical upper surface.

  Therefore, as shown in FIG. 17, the upper thread portion Ta smoothly moves upward along the upper surface of the yarn avoiding cap 50, and the upper thread portion Ta is stretched, but when there is slack, The slack portion is stretched, and even if there is not much slack, the upper thread T is pulled out slightly from the sewing needle 11 side, the upper thread portion Ta is stretched, and the upper thread portion Ta becomes the thread avoidance cap 50. After that, the upper thread portion Ta can smoothly pass over the yarn avoiding cap 50 without any tension being applied to the upper thread portion Ta.

  As described above, according to the upper thread guide structure, in particular, the front end portion of the threading guide 28 of the threading mechanism 20 is provided with the thread avoiding cap 50 having a convex spherical surface on the upper surface, and the needle bar switching mechanism provides a needle bar case. Since the upper thread portion Ta extending from each sewing needle 11 to the thread holding portion 35 is guided by the thread avoidance cap 50 when the needle 4 is moved in the left-right direction, the threading guide 28 is moved closer to the sewing needle 11, The guideability of the threading guide 28 that guides the threading hook 30 is improved, and the threading hook 30 is surely passed through the eye 11a of the sewing needle 11 at the use position so that the threading can be threaded. When the bar case 4 is moved in the left-right direction, the upper thread portion Ta extending from each sewing needle 11 to the thread holding portion 35 is caught by the threading guide 28, and the thread end of the upper thread 28 is detached from the thread holding portion 35. Surely prevent It can be.

  Since the thread avoidance cap 50 is detachably attached to the threading guide 28, the thread avoidance cap 50 can be easily attached to and detached from the front end portion of the threading guide of the threading mechanism. Since the fitting hole 53 into which the front end portion of the threading guide 28 is fitted is formed in the thread avoiding cap 50, the front end portion of the threading guide 28 is fitted into the fitting hole 53 of the yarn avoiding cap 50, The thread avoidance cap 50 can be easily attached to the threading guide 28.

  At least a front end portion of the threading guide 28 is formed with an engaging groove 28a in which a guide pin 27 fixed to the threading hook 30 is slidably engaged, and is formed in the fitting hole 53 inside the thread avoiding cap 50. Since the pair of engaging hooks 54 and 55 that engage with the engaging groove 28a are formed in the facing portion, the engaging hooks 54 and 55 are engaged with the engaging groove 28a of the threading guide 28 to avoid the thread. The cap 50 can be securely attached to the threading guide 28 so that it cannot be easily removed, and the engagement groove 28a of the threading guide 28 with which the guide pin 27 engages is effectively used, so that the structure is simple. This is advantageous in terms of manufacturing cost.

  A protruding portion 28c that protrudes forward is formed at the front end of the threading guide 28, and an engagement hole 56 that engages with the protruding portion 28a is formed in a portion that faces the fitting hole 53 inside the yarn avoiding cap 50. Therefore, the protruding portion 28c of the threading guide 28 is engaged with the engagement hole 56 of the thread avoiding cap 50, so that the thread avoiding cap 50 can be securely attached to the threading guide 28 without rattling.

  Note that the size and shape of the thread avoidance cap 50 are appropriately changed according to the size and shape of the tip of the threading guide 28. In addition, as a modified example in which the above-described embodiment is partially changed, a yarn avoiding portion may be integrally formed at the tip of the threading guide instead of the yarn avoiding cap 50. In addition to the upper surface of the threading guide, other surfaces (lower surface and the like) may be formed in a convex spherical shape. In addition, in the range which does not deviate from the meaning of this invention, it implements by adding various changes and can apply to various multi-needle sewing machines.

1 is a perspective view of a multi-needle sewing machine according to an embodiment of the present invention. It is a front view of a needle bar case. It is a left view of the principal part of a multi-needle sewing machine. It is a right view of the principal part of a multi-needle sewing machine. It is a front view of the principal part of a multi-needle sewing machine. It is a top view of the principal part of a multi-needle sewing machine. It is operation | movement explanatory drawing at the time of threading of a multi-needle sewing machine. It is operation | movement explanatory drawing at the time of threading of a multi-needle sewing machine. It is a perspective view from the front diagonally upper side of the yarn avoidance cap. It is a perspective view from the back diagonally upper side of the thread avoidance cap. It is a front view of a thread avoidance cap. It is a rear view of a thread avoidance cap. It is a left view of a thread avoidance cap. It is the XIV-XIV sectional view taken on the line of FIG. It is the XV-XV sectional view taken on the line of FIG. It is explanatory drawing at the time of guiding an upper thread | yarn with a thread | yarn avoidance cap. It is explanatory drawing at the time of guiding an upper thread | yarn with a thread | yarn avoidance cap.

Explanation of symbols

M Multi-needle sewing machine 4 Needle bar case 10 Needle bar 11 Sewing needle 11a Stitch 20 Threading mechanism 27 Guide pin 28 Threading guide 28a Engaging groove 28c Protrusion 35 Thread holding part 30 Threading hook 50 Thread avoidance cap 53 Fitting Hole 54, 55 Engagement hook 56 Engagement hole

Claims (5)

A needle bar case with multiple needle bars, a needle bar switching mechanism that selectively moves one of the needle bars to the operating position by moving the needle bar case, and a needle bar at the operating position In a multi-needle sewing machine comprising a threading mechanism for passing an upper thread through the stitch hole of the sewing needle and a thread holding part for retaining the thread end of the upper thread extending from each sewing needle on the rear side of the sewing needle,
The threading mechanism includes a threading hook that can be penetrated from the rear side into the eye hole of the sewing needle at a use position, a retracted position that is provided on the rear side of the sewing needle and that extends through the eye hole of the sewing needle, and A threading guide that is switchably guided over
A thread avoidance portion having at least an upper surface convex spherical shape is provided at the front end portion of the threading guide,
An upper thread guide for a multi-needle sewing machine configured to guide the upper thread portion extending from each sewing needle to the thread holding portion by the thread avoiding portion when the needle bar case is moved by the needle bar switching mechanism. Construction.   The upper thread guide structure of the multi-needle sewing machine according to claim 1, wherein the thread avoiding portion is detachably attached to a threading guide.   The upper thread guide structure of the multi-needle sewing machine according to claim 2, wherein a fitting hole into which a front end portion of a threading guide is fitted is formed in the thread avoiding portion. At least a front end portion of the threading guide is formed with an engaging groove for slidably engaging a guide pin fixed to the threading hook,
4. The upper thread guide structure of the multi-needle sewing machine according to claim 3, wherein an engagement hook that engages with the engagement groove is formed in a portion facing the fitting hole inside the thread avoiding portion. A protruding portion protruding forward is formed at the front end portion of the threading guide,
The upper thread guide structure of the multi-needle sewing machine according to claim 4, wherein an engagement hole for engaging the protruding portion is formed at a portion facing the fitting hole inside the thread avoiding portion.