JP2007068893A - Thread-winding-out apparatus of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thread-winding-out apparatus of a sewing machine by which the lower thread can be taken off with a single tread-winding cam at the same timing for items to be sewed with different thicknesses to prevent a decrease in operation efficiency and an increase in cost. <P>SOLUTION: This thread-winding-out apparatus 100 has a sprawl wire-driving shaft 1, a swing arm 2, a pair of cam members 6 which swings along the swinging action of the swinging arm 2, forms a cam face 61 for winding out a lower tread T by changing its position against a tread hole 91 for a tread guide 9 and has a tread-pulling section 62 and a winding-out section 63 on the cam face 61, a tread-taking-off section 7, and a tread-guiding base 8. The tread-guiding base 8 is constituted to allow its fixing position and fixing angle to be controlled so that the timing for taking off the lower tread T by the read-taking-off section 7 during the retrocession of a looper 24 is kept constant even when the timing for taking off the lower tread T by the tread-pulling section 62 during the progression of a looper 24 is changed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thread feeding device for a sewing machine.

  In a sewing machine that performs chain stitch, it is necessary to drop a needle through which an upper thread has passed through a lower thread loop formed by a lower thread that has passed through a looper. At this time, if the tension is not sufficiently applied to the lower thread loop, the lower thread loop is loosened, and it is difficult to make the lower thread loop fall well. Therefore, a yarn feeding device is provided to apply tension to the lower thread loop when the needle is dropped. The yarn feeding device is provided behind the looper in the backward direction, and has a looper shaft that reciprocates the looper back and forth as a drive source. As shown in FIG. Cams 301 and 302 are juxtaposed in the front and back direction with respect to the paper surface of FIG. That is, when the looper shaft swings, the looper reciprocates back and forth, and the yarn reeling cams 301 and 302 swing in the same direction as the looper shaft.

A thread removing member 304 for removing the lower thread 303 is provided between the pair of yarn reeling cams 301 and 302, and the thread removing member 304 is fixed to the sewing machine body. Further, thread guides 305 and 306 are provided so as to sandwich the pair of thread reeling cams 301 and 302 from the outside, and the lower thread 303 guided by these thread guides 305 and 306 is at the upper edge of the thread reeling cams 301 and 302. It is locked. The yarn reeling cams 301 and 302 are formed in a substantially mountain shape that protrudes upward most in the vicinity of the center in the front-rear direction, and the lower yarn 303 is detached by exceeding the protruding portions 301a and 302a.
Then, when the yarn reeling cams 301 and 302 move forward due to the swing of the looper shaft, the lower thread 303 moves rearward along the upper edge of the yarn reeling cams 301 and 302, and the lower yarn 303 is released at the protruding portions 301a and 302a. . The released lower thread 303 is sandwiched between the thread reeling cams 301 and 302 and the thread removing member 304 as shown in FIG. 9B, and the tension of the lower thread 303 is increased by moving the thread reeling cams 301 and 302 backward. By applying and further retreating, the lower thread 303 can be removed at the protrusions 301a and 302a (see, for example, Patent Document 1).
Japanese Patent Publication No. 5-50955

By the way, when sewing is performed using the sewing machine as described above, since the thickness of each sewing product is different, it is necessary to change the stroke of the needle in accordance with the thickness. In sewing, the looper picks up the upper thread. It is preferable that the timing and the timing at the time of needle drop are constant regardless of the stroke of the needle. For this purpose, it is necessary to change the movement amount of the looper in accordance with the needle stroke.
However, in the yarn feeding device, both the looper and the yarn feeding cam are driven by the swinging of the looper shaft, and therefore the swinging amount of the yarn feeding cam changes when the movement amount of the looper is adjusted. At this time, the timing at which the lower thread is removed when the looper is retracted can be adjusted by changing the attachment position of the thread removing member to the sewing machine body. However, the timing at which the lower thread is removed when the looper is advanced changes the shape of the thread take-up cam. Therefore, it is necessary to manufacture a plurality of thread reeling cams according to the thickness of the sewing product and replace them appropriately according to the sewing product to be sewn, resulting in a decrease in work efficiency and an increase in cost. .

  Accordingly, the present invention has been made to solve the above-mentioned problems, and even for sewing products having different thicknesses, the bobbin thread can be removed at the same timing with a single thread reeling cam, resulting in a reduction in work efficiency. An object of the present invention is to provide a sewing machine yarn feeding device capable of suppressing an increase in cost.

  In order to solve the above-described problems, the invention according to claim 1 is provided on a balance drive shaft that reciprocally moves a looper that swings around an axis and entangles a lower yarn with an upper yarn, and the balance drive shaft. A swing arm that swings in accordance with the swing operation of the balance drive shaft, a thread guide that is arranged in parallel at a predetermined interval and that has a thread hole through which a lower thread is inserted, and the swing A cam surface is formed on the arm that swings with the swinging motion of the swinging arm at a position between the thread guide thread holes and feeds the lower thread by displacement with respect to the thread hole. Is disposed between the pair of cam members, and a pair of cam members having a yarn pulling portion that removes the lower thread when the looper moves forward, and a feeding portion that feeds the lower thread when the looper moves backward And holds the lower thread fed by the feeding section when the looper is retracted Both a thread removing member for removing the lower thread fed by the feeding section at a predetermined timing, and a thread guide base provided on the sewing machine body to which the thread guide and the thread removing member are attached. In the feeding device, the thread guide base may be configured so that the timing at which the lower thread is removed by the thread removal member when the looper is retracted when the timing at which the lower thread is removed by the thread pulling portion when the looper moves forward is changed In order to maintain, the attachment position and the attachment angle to the sewing machine main body are configured to be adjustable.

According to the first aspect of the present invention, when the balance driving shaft is swung around the axis, and the looper that entangles the upper thread with the lower thread is reciprocated, the swing arm provided on the balance driving shaft is: Oscillates as the scale drive shaft swings. By swinging the swing arm, the thread pulling portion of the cam member removes the lower thread when the looper moves forward, and the feeding portion feeds the lower thread when the looper moves backward. Further, the thread removing member holds the lower thread fed by the feeding section when the looper moves backward, and removes the lower thread fed by the feeding section at a predetermined timing.
Here, when the thickness of the sewing product to be sewn changes, it is necessary to change the stroke of the needle according to the thickness, and as the needle stroke changes, the thread removal member is attached to the thread guide base. It becomes necessary to change the timing of removing the lower thread by changing the position and the shape of the thread drawing portion.
Even in such a case, when changing the timing at which the lower thread is removed by the yarn pulling portion when the looper moves forward, the yarn guide base keeps the timing at which the lower thread is removed by the yarn removing member when the looper moves backward. Since the attachment position and attachment angle to the sewing machine body can be adjusted, the thickness of the sewing product to be sewn can be increased by changing the attachment position and attachment angle to the sewing machine body. Even if it changes, the timing to remove the lower thread can be kept constant, and even with different thicknesses, it is possible to remove the lower thread at the same timing with a single thread reel cam, resulting in lower work efficiency and cost. Can be suppressed.

  According to a second aspect of the present invention, in the yarn feeding device for the sewing machine according to the first aspect, the thread guide base is configured to move when the looper is retracted when the mounting angle of the cam member with respect to the balance drive shaft is changed. The attachment position to the sewing machine main body and the attachment angle can be adjusted so that the timing at which the lower thread is removed by the thread removal member is kept constant.

According to the second aspect of the present invention, when the attachment angle of the cam member to the balance drive shaft is changed, the attachment position of the yarn removing member to the yarn guide base and the shape of the yarn pulling portion are matched to the attachment angle. Therefore, it is necessary to change the timing for removing the lower thread.
Even in such a case, the thread guide base is attached to the sewing machine main body so that the timing at which the lower thread is removed by the thread removal member when the looper is retracted is kept constant when the mounting angle of the cam member with respect to the balance drive shaft is changed. The attachment position and attachment angle of the cam member can be adjusted, so that the attachment angle of the cam member to the scale drive shaft can be changed by changing the attachment position and attachment angle of the thread guide base to the sewing machine body. The timing for removing the lower thread can be kept constant, and the lower thread can be removed at the same timing with a single thread-feeding cam, so that reduction in work efficiency and increase in cost can be suppressed.

  A third aspect of the present invention is the yarn feeding device for the sewing machine according to the first or second aspect, further comprising an adjustment mechanism that can adjust an attachment position and an attachment angle to the sewing machine body, and the adjustment mechanism includes A groove formed in the thread guide base, an eccentric collar that is fitted at least in the groove so as to be rotatable and slidable, and a fastening member that is inserted through the eccentric collar and fixes the thread guide base to the sewing machine body; It is characterized by having.

According to the invention described in claim 3, since the fastening member for attaching the thread guide base to the sewing machine body is inserted through the eccentric collar, the eccentric collar can be rotated or slid in the groove. The attachment position and the attachment angle of the thread guide base to the sewing machine main body will change.
As a result, if it is necessary to change the timing of removing the lower thread by changing the attachment position of the thread removing member to the thread guiding base or the shape of the thread pulling portion, the sewing machine main body of the thread guiding base is moved by moving the eccentric collar. The timing to remove the lower thread can be kept constant by changing the attachment position and angle to the lower thread, so it is possible to remove the lower thread at the same timing with a single thread reel cam, reducing work efficiency and increasing costs. Can be suppressed.

  According to a fourth aspect of the present invention, in the yarn feeding device for a sewing machine according to the third aspect, a plurality of the eccentric collars are provided in the groove, and the same number of the fastening members as the eccentric collars are provided. .

According to the invention described in claim 4, by providing a plurality of eccentric collars, the range in which the posture of the thread guide base with respect to the sewing machine body can be expanded.
Therefore, the range in which the timing for removing the lower thread can be adjusted can be expanded, and the versatility of the sewing machine can be improved.

  According to the first aspect of the present invention, the timing for removing the lower thread can be kept constant even when the thickness of the sewn product to be sewn changes, The bobbin thread can be removed at the same timing by the thread take-up cam, and a reduction in work efficiency and an increase in cost can be suppressed.

  According to the second aspect of the present invention, the timing for removing the lower thread can be kept constant even if the mounting angle of the cam member with respect to the balance drive shaft changes, and the lower thread is removed at the same timing with a single reel cam. It is possible to suppress a decrease in work efficiency and an increase in cost.

  According to the third aspect of the present invention, when there is a need to change the timing of removing the lower thread by changing the attachment position of the thread removal member with respect to the thread guide base or the shape of the thread drawing portion, the eccentric collar is moved. By changing the attachment position and angle of the thread guide base to the sewing machine body, the timing to remove the lower thread can be kept constant, so the lower thread can be removed at the same timing with one thread reeling cam. Reduction in efficiency and increase in cost can be suppressed.

  According to the invention described in claim 4, the range in which the timing for removing the lower thread can be adjusted can be expanded, and the versatility of the sewing machine can be improved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode of a thread feeding device for a sewing machine according to the present invention will be described in detail with reference to the drawings.
<Configuration of the thread feeding device>
As shown in FIG. 1, a thread take-up device 100 is provided on a balance drive shaft 1 that swings around an axis by a drive force from a sewing machine motor (not shown) as a drive source. A proximal end portion of the swing arm 2 is attached to a distal end portion of the balance driving shaft 1 by a set screw 3. Here, since the swing arm 2 can be freely rotated with respect to the balance drive shaft 1 and can be fixed by a set screw 3 at an arbitrary position, the swing arm 2 is attached to the balance drive shaft 1. The angle can be changed. A yarn reel adjusting cam 4 is attached to the tip of the swing arm 2 by a set screw 5. A pair of large cams 6, 6 as a pair of cam members are attached to the front end portion of the swing arm 2 by a set screw 5 on the back side of the yarn reel adjusting cam 4. The large cams 6 and 6 swing along with the swinging motion of the swinging arm 2 at a position between the thread guides 91 (described later) of the thread guide 91 and feed the lower thread T by displacement with respect to the thread hole 91. Cam surfaces 61 and 61 are formed.

  As shown in FIG. 2, the cam surfaces 61 and 61 of the large cams 6 and 6 are formed in front of the large cams 6 and 6 (on the looper 24 side), and are used to remove the lower thread T when the looper 24 moves forward. A pulling part 62 and a feeding part 63 for feeding the lower thread T when the looper 24 moves backward are formed behind the large cams 6 and 6. The yarn pulling portion 62 is formed in a substantially mountain shape that protrudes most upward in the vicinity of the center in the front-rear direction, and the lower yarn T comes off when the lower yarn T crosses the protruding portion 62a. The feeding portion 63 formed at the rear of the yarn drawing portion 62 is formed so as to hang downward, and is formed so as to intersect with the upper end edge of the yarn removing finger 7 (described later).

  The pair of large cams 6 and 6 holds the lower thread T fed by the feeding section 63 when the looper 24 moves backward, and removes the lower thread T fed by the feeding section 63 at a predetermined timing. A thread removal finger 7 as a member is provided. The yarn removal finger 7 has a curved surface with a smooth upper end edge, and a rear end portion thereof is an inclined surface 71 that inclines upward rapidly. The inclined surface 71 is formed so as to extend at least at the upper end of the feeding portion 63, that is, above the boundary position between the yarn drawing portion 62 and the feeding portion 63. This prevents the lower thread T from being caught behind the thread removal finger 7 when the lower thread T locked to the feeding part 63 extends over the yarn pulling part 62.

The thread release finger 7 is attached to a thread guide base 8 provided in the sewing machine body, and the thread release finger 7 can be attached to the thread guide base 8 at a plurality of positions. A groove 81 is formed in the base end portion of the yarn guide base 8 along the vertical direction when the yarn guide base 8 is attached. In the groove 81, a plurality of at least rotating and sliding movements within the groove 81 are possible. (For example, two) eccentric collars 82 are fitted. Here, the eccentric collar 82 includes a substantially cylindrical shaft portion 82a fitted in the groove 81, and a substantially disk-shaped collar portion 82b formed at the tip of the shaft portion 82a. The shaft portion 82a is formed with a screw hole penetrating from the front end toward the rear end at a position eccentric with respect to the axis. Further, the collar portion 82b is formed with a screw hole penetrating from the front end toward the rear end at a position eccentric with respect to the axis thereof, and the screw hole is formed coaxially with the screw hole of the shaft portion 82a. Has been.
The thread guide base 8 is fixed to the sewing machine main body by inserting a set screw 83 as a fastening member into the collar portion 82b of each eccentric collar 82 and the screw hole of the shaft portion 82a. The groove 81, the eccentric collar 82, and the set screw 83 constitute an adjustment mechanism 80 that can adjust the attachment position and the attachment angle of the thread guide base 8 to the sewing machine body. That is, by changing the fitting position of the eccentric collar 82 in the groove 81 and attaching it to the sewing machine main body, it is possible to adjust the attachment position of the thread guide base 8 with respect to the sewing machine main body, and the eccentric collar 82 is rotated in the groove 81 to adjust the sewing machine main body. The attachment angle of the thread guide base 8 with respect to the sewing machine body can be adjusted.

Here, a method of adjusting the attachment position and the attachment angle of the yarn guide base 8 to the sewing machine body by the adjustment mechanism 80 will be described.
As shown in FIGS. 3 and 4, the set screw 83 is loosened from the state where the thread guide base 8 is attached along the vertical direction of the sewing machine (the two-dot chain line in FIG. 3), and the eccentric collar 82 is rotated and slid. Let The fixing position of the set screw 83 to the sewing machine main body is not changed, and the screw hole through which the set screw 83 is inserted in the eccentric collar 82 is formed at an eccentric position. 81 is pushed out by the eccentric collar 82 so as to be inclined. For example, as shown in FIG. 3, when each eccentric collar 82 is rotated 90 ° counterclockwise, the groove 81 is pushed by the shaft portion 82a of each eccentric collar 82 so as to incline to the left, as shown in FIG. In addition, the yarn guide base 8 is inclined to the left (solid line in FIG. 3). Therefore, the inclination angle of the yarn guide base 8 can be changed according to the rotation angle of the shaft portion 82 a of the eccentric collar 82 and the movement distance in the groove 81.

  By this adjusting mechanism 80, the thread guide base 8 removes the lower thread T by the thread removal finger 7 when the looper 24 moves backward when the timing at which the lower thread T is removed by the thread pulling portion 62 is changed when the looper 24 moves forward. The timing can be kept constant. Further, when the attachment angle of the large cams 6 and 6 with respect to the balance drive shaft 1 is changed by the adjusting mechanism 80, the timing at which the lower thread T is removed by the yarn removal finger 7 when the looper 24 moves backward is constant. Will be able to keep on.

  Three thread guides 9, 9, 9 are provided outside the pair of large cams 6, 6 so as to sandwich the pair of large cams 6, 6 at a predetermined interval. A thread hole 91 through which the lower thread T is inserted is formed at the tip of each thread guide 9, 9, 9. The lower thread T inserted through the thread hole 91 is connected to the cam surfaces 61, 6 of the large cams 6, 6. It is locked to 61 and reaches the looper 24. Each thread guide 9, 9, 9 is attached to a thread guide arm 10, and this thread guide arm 10 is attached to a thread guide base 8 with a set screw 12 via a bracket 11.

<Configuration of looper mechanism>
As shown in FIG. 1, the balance driving shaft 1 is provided with a looper mechanism 200. A base end portion of a looper arm 21 is attached to the balance driving shaft 1, and a looper shaft 22 is connected to a distal end portion of the looper arm 21. Here, the looper shaft 22 is arranged so that its axis is substantially perpendicular to the balance drive shaft 1 and the looper arm 21, and reciprocates along the axial direction by the swing of the balance drive shaft 1. It has become. A looper base 23 is attached to the tip of the looper shaft 22, and a looper 24 is attached to the looper base 23 with a set screw 25.

<Operation of the thread feeding device>
Next, the operation of the yarn feeding device 100 will be described.
5A to 5F individually correspond to FIGS. 6A to 6F.
As shown in FIG. 5A, when the needle 30 is at the bottom dead center, the looper 24 is in the rearmost position. At this time, as shown in FIG. 6A, the lower thread T is in the thread drawing portions 62 and 62 on the cam surfaces 61 and 61 of the large cams 6 and 6.
Next, as shown in FIG. 5 (b), as the needle 30 moves up and the looper 24 moves forward, the lower thread T moves to the thread drawing portions 62, 62 as shown in FIG. 6 (b). It moves gradually backward while being locked.
Next, as shown in FIG. 5C, when the needle 30 is at the top dead center, the looper 24 is in the foremost position. At this time, as shown in FIG. 6C, the lower thread T is in the feeding portions 63 and 63 on the cam surfaces 61 and 61 of the large cams 6 and 6.

Next, as shown in FIG. 5 (d), as the needle 30 descends and the looper 24 moves backward, the lower thread T pushes against the feeding portions 63 and 63 as shown in FIG. 6 (d). Then, tension is started to be applied to the lower thread T. As a result, the lower thread loop is not loosened.
Next, as shown in FIG. 5 (e), as the needle 30 is further lowered and the looper 24 is moved backward, the lower thread T is fed from the feeding portions 63 and 63 as shown in FIG. 6 (e). When the transition is made toward the yarn drawing portions 62, 62 and the yarn drawing portions 62, 62 are changed, the tension acting on the lower yarn T becomes zero, and then the lower yarn T is moved to the yarn drawing portions 62, 62. Move forward. Thus, the tension of the lower thread T is lost.
Next, as shown in FIG. 5 (f), the needle 30 is further lowered, and the looper 24 is further moved rearward. Accordingly, as shown in FIG. 6 (f), the lower thread T moves forward and returns to the state of FIG. 6 (a).

<Effect>
According to the yarn feeding device 1 according to the embodiment, when the balance driving shaft 1 is swung around the shaft, and the looper 24 that entangles the lower yarn T with the upper yarn is reciprocated, the swing provided on the balance driving shaft 1 is swung. The moving arm 2 swings with the swing operation of the balance drive shaft 1. Due to the swing of the swing arm 2, the thread pulling portions 62, 62 of the large cams 6, 6 remove the lower thread T when the looper 24 moves forward, and the feeding portions 63, 63 move downward when the looper 24 moves backward. The thread T is fed out. Further, the yarn removing finger 7 holds the lower yarn T fed by the feeding portions 63 and 63 when the looper 24 moves backward, and removes the lower yarn T fed by the feeding portions 63 and 63 at a predetermined timing.

Here, when the thickness of the sewing product to be sewn changes, it is necessary to change the stroke of the needle 30 in accordance with the thickness, and as the needle 30 changes, the thread guide of the thread removal finger 7 is changed. It is necessary to change the timing for removing the lower thread T by changing the mounting position with respect to the base 8 and the shape of the cam surface 61 of the thread drawing portions 62 and 62.
Even in such a case, when the timing for removing the lower thread T by the thread pulling portions 62 and 62 is changed when the looper 24 moves forward, the thread guide base 8 is lowered by the thread removal finger 7 when the looper 24 moves backward. Since the attachment position and attachment angle to the sewing machine body can be adjusted so as to keep the timing for removing T constant, the thread guide base 8 is attached by changing the attachment position and attachment angle to the sewing machine body. Even if the thickness of the sewing product to be sewn changes, the timing for removing the lower thread T can be kept constant, and even with different thicknesses, one large cam 6 and 6 can be used at the same timing. The lower thread T can be removed, and a decrease in work efficiency and an increase in cost can be suppressed.

When the attachment angle of the large cams 6 and 6 with respect to the balance drive shaft 1 changes, the attachment position of the yarn removal finger 7 with respect to the yarn guide base 8 and the shape of the yarn pulling portions 62 and 62 are matched to the attachment angle. Therefore, it is necessary to change the timing for removing the lower thread T.
Even in such a case, the thread guide base 8 has a constant timing for removing the lower thread T by the thread removal finger 7 when the looper 24 is retracted when the mounting angle of the large cams 6 and 6 with respect to the balance drive shaft 1 is changed. Since the attachment position and the attachment angle to the sewing machine main body are configured to be adjustable so that the thread guide base 8 is attached to the sewing machine main body by changing the attachment position and the attachment angle to the sewing machine main body, Even if the attachment angle of the balance drive shaft 1 changes, the timing for removing the lower thread T can be kept constant, and the lower thread T can be removed at the same timing by one large cam 6, 6. Reduction and increase in cost can be suppressed.

Further, since the set screw 83 for attaching the thread guide base 8 to the sewing machine body is inserted through the eccentric collar 82, the thread guide base can be rotated by rotating or sliding the eccentric collar 82 in the groove 81. The attachment position and the attachment angle to the sewing machine main body of 8 will change.
As a result, the eccentric collar 82 is moved when it is necessary to change the timing at which the lower thread T is removed by changing the attachment position of the thread release finger 7 to the thread guide base 8 or the shape of the thread pulling portions 62, 62. By changing the attachment position and the attachment angle of the thread guide base 8 to the sewing machine main body, the timing for removing the lower thread T can be kept constant, so the lower thread T is removed at the same timing with one large cam 6, 6. It is possible to suppress a decrease in work efficiency and an increase in cost.

Further, by providing a plurality of eccentric collars 82 and 82 in the groove 81 of the yarn guide base 8, the range in which the posture of the yarn guide base 8 with respect to the sewing machine body can be changed is compared with the case where the eccentric collar 82 is one. Can be enlarged.
Therefore, the range in which the timing for removing the lower thread T can be adjusted can be expanded, and the versatility of the sewing machine can be improved.

Further, as shown in FIG. 7, when the center of the swing amplitude of the large cams 6 and 6 is on the same plane as the axis of the swing shaft 2 (so-called sorting), the large cams 6 and 6 are removed before the lower thread T is removed. 6 needs to be swung more than the distance L1, but when the swing position of the large cams 6 and 6 is closer to the front of the large cams 6 and 6 (when rotated counterclockwise), the large cams 6 and 6 The distance until the lower thread T comes off is shorter than L1, and as shown in FIG. 8, the swinging width of the large cams 6 and 6 to the right side can be reduced and the swinging width of the left side can be increased. Thereby, the distance to which the large cams 6 and 6 are swung before the lower thread T is released can be shortened from L1 to L2. Next, by keeping the relative positions of the thread hole 91 and the large cams 6 and 6 the same, the thread guide base 8 is tilted according to the inclination of the large cams 6 and 6 and the thread removal finger 7 is adjusted, When adjusting the timing at which the lower thread T is removed when the large cams 6 and 6 move to the left, the thread removal timing when the large cams 6 and 6 move to the right can be kept at the same timing as before. .
Note that the present invention is not limited to the above-described embodiment, and can be freely replaced and changed within the scope of the invention.

The perspective view which shows the structure of a thread | yarn delivery apparatus and a looper mechanism. The figure which shows the relationship between a large cam and a thread removal finger. The figure explaining an adjustment mechanism. The figure which shows the thread | yarn guide base which adjusted the attachment position and the attachment angle. The figure which shows the formation procedure of a seam. The figure explaining operation | movement of a large cam and a bobbin thread corresponding to the formation procedure of the seam in FIG. The figure which shows the positional relationship of a large cam and a thread | yarn guide base when the swing position of a large cam is divided. The figure which shows the positional relationship of a big cam and a thread | yarn guide base when the swing position of a big cam is made to the front of a big cam. The figure explaining operation | movement of the large cam and lower thread in a prior art.

Explanation of symbols

1 Balance drive shaft 2 Swing arm 6 Large cam (cam member)
7 Thread removal finger (thread removal member)
8 Thread guide base 9 Thread guide 24 Looper 61 Cam surface 62 Thread drawing part 63 Feeding part 80 Adjustment mechanism 81 Groove 82 Eccentric collar 83 Set screw (fastening member)
91 Thread hole 100 Thread feeding device 200 Looper mechanism T Lower thread

Claims (4)

A balance drive shaft that swings around an axis and reciprocally moves a looper that entangles the upper thread with the lower thread;
A swing arm provided on the balance drive shaft and swinging with a swing operation of the balance drive shaft;
Thread guides arranged in parallel at predetermined intervals, each having a thread hole through which a lower thread is inserted,
A cam surface is formed on the swing arm and swings with the swing operation of the swing arm at a position between the thread guide thread holes and feeds the lower thread by displacement with respect to the thread hole. A pair of cam members, the cam surface having a yarn pulling portion for removing a lower thread when the looper moves forward, and a feeding portion for feeding the lower thread when the looper moves backward;
A yarn removing member that is disposed between the pair of cam members, holds the lower thread fed by the feeding section when the looper is retracted, and removes the lower thread fed by the feeding section at a predetermined timing;
A thread guide base provided in a sewing machine body to which the thread guide and the thread removing member are attached;
In a thread unwinding device for a sewing machine comprising:
When changing the timing of removing the lower thread by the yarn pulling portion when the looper advances, the yarn guide base keeps the timing of removing the lower thread by the yarn removal member constant when the looper moves backward. A sewing machine thread feeding device characterized in that the attachment position and the attachment angle to the sewing machine main body are adjustable.   The thread guide base is attached to the sewing machine main body so as to keep constant the timing of removing the lower thread by the thread removing member when the looper is retracted when the angle of attachment of the cam member to the balance drive shaft is changed. 2. The sewing machine yarn feeding device according to claim 1, wherein the position and the mounting angle are adjustable. An adjustment mechanism that enables adjustment of an attachment position and an attachment angle of the thread guide base to the sewing machine main body;
The adjusting mechanism is
A groove formed in the yarn guide base;
An eccentric collar fitted in the groove so as to be at least rotatable and slidable in the groove;
A fastening member that is inserted through the eccentric collar and fixes the thread guide base to the sewing machine body;
The sewing machine yarn feeding device according to claim 1, wherein   The sewing machine thread feeding device according to claim 3, wherein a plurality of the eccentric collars are provided in the groove, and the same number of the fastening members as the eccentric collars are provided.

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