JP3104076B2 - sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine capable of performing loop stitching on a cloth, and more particularly, to a sewing machine capable of changing the length of a loop to be long or short.

[0002]

2. Description of the Related Art A conventional sewing machine of this type has a vertical movement range of a needle bar which is moved upward or downward as a whole, that is, a vertical movement of a hook needle which moves up and down integrally with the needle bar. In FIG. 7B in which the range is indicated by the reference symbol R, the bottom dead center L is raised almost in parallel with the rise of the top dead center U, so that a long loop or a short loop is sewn. I do it. (For example, Japanese Patent Publication No. 64-
No. 2396)

[0003]

In this conventional sewing machine, sewing of a long loop and sewing of a short loop can be performed without trouble in the case of a normal thread. However, when trying to sew long or short loops in the case of a thicker thread,
Some of the fibers in the thread do not catch on the hooks of the hooks, and as shown in FIG. 5C, some of the fibers 71a that did not catch on the hooks were sufficiently pulled up from the cloth 70. There was a problem that the sewing was not performed properly. That is, there is a problem in that the yarn to be used is restricted.

The present invention has been made to solve the above-mentioned problem (technical problem) of the prior art, and the width of the vertical movement of the needle bar is decreased from the bottom dead center with the rise of the top dead center. It is an object of the present invention to provide a sewing machine which can appropriately sew any kind of thread from a long loop to a short loop.

[0005]

The sewing machine according to the present invention has a vertically movable needle bar having a hook at the lower end above a needle plate, and a rotatable looper below the needle bar. And a drive mechanism connected to the looper so that the needle bar can be sewn on the cloth on the needle plate by the vertical movement of the needle bar and the rotation of the looper. A driving lever for performing a swinging motion, and a linkage mechanism for transmitting the swinging motion of the driving lever to the needle bar by changing the swinging motion into a vertical movement, and the linkage mechanism includes a needle. As the top dead center of the rod rises,
Adjustment means for changing the vertical movement width of the needle bar so that the bottom dead center is sequentially lowered is provided.

[0006]

When the drive lever swings, the needle bar is moved up and down via the linkage mechanism. On the other hand, the looper is also rotated by its drive mechanism. As a result, the cloth is loop-stitched.
When the upper dead center of the needle bar is changed to be higher or lower by the adjusting means, the lower dead center is correspondingly deeper or shallower, and the upper dead center of the needle bar is changed to be higher or lower with respect to the rotation of the hole of the hook. Even though the yarns are consistent, the hook is constant irrespective of the type of yarn, the loops formed on the cloth are beautiful, and the length is longer or shorter respectively.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing FIG. 8 showing an embodiment of the present invention, FIGS. 1 to 7 showing related technical matters will be described. In FIG. 1, reference numeral 1 denotes a needle plate, reference numeral 2 denotes a needle hole, and reference numeral 3 denotes a well-known looper provided below the needle plate 1, which is horizontally reciprocated, for example, by a driving mechanism (not shown). Reference numeral 4 denotes a sewing head provided above the needle plate 1. Hereinafter, the sewing machine head will be described. 5 is a frame, 6 is the front side of the frame 5 (left side in FIG. 1)
, A needle bar mounted on the support frame 6 so as to be vertically movable, 8 is a drive mechanism provided on the frame 5,
This is for moving the needle bar 7 up and down, and is operated in conjunction with the looper drive mechanism. The drive mechanism 8 will be described. A drive shaft 9 is continuously rotated by a main motor (not shown). Ten
Is a drive lever which swings at a fixed angle. Reference numeral 11 denotes a linking mechanism for transmitting the swinging motion of the driving lever 10 to the needle bar 7 by changing it into a vertical motion.
The adjustment means attached to the above is for changing the vertical movement width of the needle bar 7. Reference numeral 13 denotes a nipple holding cylinder mounted on the support frame 6 so as to be vertically movable.

The needle bar 7 and its related structure will be described in detail. Reference numeral 15 denotes a well-known hook attached to the lower end of the needle bar 7, the lower end of which is configured as shown in FIG.
That is, reference numeral 16 denotes a hook portion, 17 denotes a hole portion, and 18 denotes a sewing thread catching portion. Returning to FIG. 1, reference numeral 20 denotes a needle bar guide cylinder, which is rotatably mounted on the support frame 6 and which is prevented from coming off by a stopper 21. The needle bar 7 is housed inside the guide tube 20 so as to be vertically movable. A vertically long connecting groove 22 is formed in the upper part of the guide cylinder 20, and a direction control shaft for controlling the direction of the hook 16 of the hook 15 through a pair of connecting gears 23 in the middle part.
Connected to 24.

Next, a description will be given of the drive lever 10 and the related structure between the drive lever 10 and the drive shaft 9. The drive lever 10 has one end pivotally connected to the frame 5 by a pivotal fixture 26. FIG.
26a is a bearing metal. The free end of the driving lever 10 is provided with a connecting portion 27 as shown mainly by broken lines in FIG. In this example, the connecting portion 27 is formed in a forked shape as shown in the figure. Reference numeral 28 denotes a main cam mounted on the drive shaft 9 and having a cam groove 29, and a guide 30 mounted on an intermediate portion of the driving lever 10 is located in the cam groove 29. Rollers are used as the guides 30 in order to reduce friction with the cam grooves 29.

Next, the linking mechanism 11 will be described. Reference numeral 31 shown in FIG. 1 denotes an elevating frame, which is vertically movably mounted in a vertically long guide groove 32 formed on the back surface of the support frame 6. 33 is the lifting frame
A window formed in 31 allows the direction control shaft 24 to pass therethrough. Reference numeral 34 denotes an engagement piece provided at the upper end of the lifting frame 31. Next, reference numeral 35 denotes a connecting device for connecting the lifting frame 31 and the needle bar 7 to each other. 36 is a main body of the connecting device,
And is attached to the needle bar guide tube 20 so as to be vertically movable. Reference numeral 37 denotes an engagement groove provided around the main body 36, and the engagement piece 34 is engaged with a part of the engagement groove. Reference numeral 38 denotes a needle bar gripping frame which surrounds the needle bar 7, a part of which is located in the connecting groove 22, and is connected to the main body 36 with a set screw 39. Reference numeral 40 denotes a fastener screwed to the main body 36, and a fastener 41 is provided at the tip thereof.
The holding frame 38 is used to integrate the main body 36 and the needle bar 7.

Reference numeral 44 denotes a transmission lever in the link mechanism 11 for transmitting the movement of the driving lever 10 to the lifting frame 31. A connecting member 45 connects the driving lever 10 and the transmission lever 44 to each other. Transmission lever above
44 is rotatably mounted on a control shaft 54 of the adjusting means 12 which will be described later. 47 and 48 are a pair of interlocking members for interlocking the elevating frame 31 and the transmission lever 44. In this example, a bifurcated interlocking body 47 is attached to the elevating frame 31 and a pin is attached to one end of the interlocking lever 44. Is engaged with the interlocking body 47. However, their relationships may be reversed. Reference numeral 50 denotes a connecting portion provided at the other end of the interlocking lever 44, which is formed bifurcated in this embodiment. Next, as shown in FIG. 3, the link 45 is engaged with the link 27 of the drive lever 10, that is, the drive lever link 51 located inside the fork in this example, and the link in the transmission lever 44. A transmission lever connecting portion 52 that engages similarly to the portion 50 is provided.

Returning to FIG. 1, the adjusting means 12 will be described.
54 is a control shaft for controlling the vertical movement width of the needle bar, 55 is an eccentric cam fixed to the control shaft 54, 56 is a bearing, which is rotatably mounted on the cam 55 via a bearing metal 57. , FIG.
The intermediate portion of the connecting member 45 is attached to the support body 56 as shown in FIG. In FIG. 3, 58 and 59 indicate positioning collars mounted on the control shaft 54, 60 and 61 indicate thrust washers, and 62 indicates a bearing provided between the control shaft 54 and the transmission lever 44, respectively. 63 is a control motor connected to the control shaft 54, for example, a stepping motor is used, and a control means for controlling the length of the loop to be sewn, such as a computer, controls the rotation angle. .

Next, referring back to FIG. 1, the relation of the nipple holding cylinder 13 will be described. 65 is a guide cylinder attached to the support frame 6,
Along with this, the nipple holding cylinder 13 moves up and down. A well-known nipple 66 is provided at the lower end of the nipple holding cylinder 13.
The upper end is provided with a connecting portion 67 with a control member 68 for moving the holding cylinder 13 up and down.

Next, the vertical movement of the needle bar 7 when sewing on a cloth by the sewing machine having the above-described configuration will be described. By the rotation of the drive shaft 9, the drive lever 10 repeats the swinging motion at a certain angle via the main cam 28 and the guide 30 as shown in FIGS. The movement of the driving lever 10 is transmitted to the transmission lever 44 via the connecting member 45, and the lever 44 swings about the shaft 54. The swinging motion is a pair of interlocking members 4
It is transmitted to the lifting frame 31 via 7 and 48, and the lifting frame 31 moves up and down. The vertical movement of the lifting frame 31 is transmitted to the main body 36 of the connecting tool 35 through the engagement between the engagement piece 34 and the engagement groove 37, and further, the grip frame 38
To the needle bar 7, and the needle bar 7 moves up and down.

The control of the direction of the hook 16 in the hook 15 is as follows. When the direction control shaft 24 rotates by a predetermined angle, the guide cylinder 20 rotates by a corresponding angle via the gear 23. The rotation is transmitted to the holding frame 38 located in the groove 22,
The needle bar 7 rotates by the same angle as the guide cylinder 20. as a result,
The hook 16 of the hook 15 is oriented in a predetermined direction. The setting of the direction is well known, and when performing loop stitching, the hook 16 is directed in the same direction as the moving direction of the cloth. If the direction is reversed, well-known chain stitching can be performed.

Next, the sewing of a loop to the cloth 70 on the needle plate 1 will be described. The nipple 66 is moved up and down in conjunction with the operation of the needle bar 7 as described above, and the looper 3 is reciprocally rotated as shown in FIG. 4, and the thread 71 sent out through the vertical groove 3a for guiding the sewing thread in the looper 3. As a result, as shown in FIG.
The sewing of the loop 72 is performed for 70. In FIG. 4, the rotation angle of the drive shaft indicates the rotation angle from 0 ° when the state immediately before the needle bar 7 starts descending from the top dead center is 0 °. The rotation angle of the drive shaft 9 of the needle bar 7 is approximately 130 °.
Is the bottom dead center. The state of the looper 3 reciprocatingly rotating in conjunction with the drive shaft 9 and the state of the thread 71 fed from the longitudinal groove 3a in the looper 3 are shown corresponding to various rotation angles of the drive shaft 9. . Reference numeral 73 indicates a point at which the thread 71 is connected to the cloth 70. The rotation angle of the drive shaft 9 of the looper 3 is 0.
The clockwise rotation is performed as the angle increases from ゜, and when the rotation angle of the drive shaft becomes about 210 °, the clockwise rotation angle becomes maximum, and the stopped state is maintained until the rotation angle of the drive shaft is about 225 °. Then, as the rotation angle of the drive shaft increases, the motor rotates counterclockwise, and returns to the original position when the rotation angle of the drive shaft reaches 360 °. The direction and angle of rotation of the looper are set in various sewing machines.

When the sewing is performed as described above, when the rotation angle of the drive shaft 9 is 190 °, that is, immediately before the clockwise rotation angle of the looper is maximized, the operation is performed as shown in FIG. As shown, the portion 18a immediately above the sewing thread catching portion 18 of the hook 15 in the ascending process passes through the position of the thread 71 (the thread between the outlet of the vertical groove 3a in the looper 3 and the cloth 70), and the drive shaft When the rotation angle of the looper 3 becomes the maximum, that is, 210 degrees, the gouge 17 of the hook 15 rises to the position of the thread 71. In this process, the thread 71 is in a sufficiently stretched state, so that the thread 71 surely falls into the sewing thread catching section 18 and enters the scooping section 17 without fail.
That is, all of the yarn 71 enters the undercut 17.
As a result, unlike the conventional example shown in FIG. 5 (C), an accident that some fibers 71a are not sufficiently lifted from the cloth 70 does not occur, and is shown in FIG. 5 (B). Like, thread
At 71, the entirety of the fiber is reliably pulled up from the cloth 70, and an appropriate loop 72 is formed.

Next, the change of the loop length will be described. When changing the loop length to be longer, the control shaft 54 is rotated by a predetermined angle by the motor 63 according to a command from the control means. Then, the support body 56 is displaced by the eccentric cam 55, and the connecting member 45 is repositioned in the connecting portion 27 of the driving lever 10 in a direction away from the pivot attachment 26. For example, it moves from a position indicated by reference numeral 45a in FIG. 6 to a position indicated by 45b. As a result, even if the swing angle θ1 of the drive lever 10 is constant,
The transmission lever 44, which used to have a small swing width as indicated by reference numeral 44a in FIG. 6, swings with a large swing width as indicated by reference numeral 44b. As a result, the vertical movement range of the needle bar 7 increases. In this case, in this embodiment, the displaceable direction of the connecting member 45 in the connecting portion 27 of the driving lever 10, that is, the center line of the gap in the bifurcated connecting portion 27, and the connecting member 45 in the connecting portion 50 of the transmission lever 44. , That is, the center line of the gap in the bifurcated connecting portion 50 is overlapped with the needle bar 7 at the bottom dead center, so that the vertical movement width of the needle bar 7 is as described above. Is increased, the position of the bottom dead center of the needle bar 7 does not change, and only the position of the top dead center gradually increases. As described above, when the position of the top dead center of the needle bar 7 rises, the hook 16 of the hook needle 15 is lifted from the needle plate 1 to a higher position, so that a long loop (for example,
11 mm). On the other hand, when the loop length is shortened in the opposite manner, the control shaft 54 is rotated by another predetermined angle, and the connecting element 45 is positioned at the connecting portion 27 of the driving lever 10 close to the pivot attachment 26. Is displaced. Then, the swing angle of the transmission lever 44 decreases, and the vertical movement width of the needle bar 7 decreases. Also in this case, the position of the bottom dead center does not change, and only the position of the top dead center is lowered. As a result, the hook 16 of the hook 15
Is raised, and a short loop (for example, 3 mm) is formed.

FIG. 7A shows a case where the loop length is changed as described above. The arrow R indicates the vertical movement range of the hook 16 in the hook 15, U indicates the top dead center, and L indicates the position of the bottom dead center. As is apparent from this figure, the position L of the bottom dead center is kept substantially constant even when the position U of the top dead center rises. As described above, the position of the hook 16 at the time when the rotation angle of the drive shaft 9 becomes approximately 190 ° (just before the rotation angle of the looper becomes the maximum) is indicated by a symbol P in the drawing. Position. Therefore, in both cases where the position U of the top dead center is low and a short loop is formed, and where the position U of the top dead center is high and a long loop is formed, the thread is sufficiently formed as described above. In a stretched state, the sewing thread catching section 18 and the undercut section 17 move up the position of the thread 71, and as a result, the thread 71 is securely hooked on the undercut section 17. Therefore, even when a short loop or a long loop is sewn using a thicker yarn, proper sewing can be performed.

Next, the relationship between the connecting portion 27 of the driving lever 10 and the connecting member 45 is such that the connecting member 45 can be moved far and near with respect to the swing center of the driving lever 10 (the center position of the pivotal attachment 26). Other structures can be used as long as the structure is used. The same applies to the relationship between the connecting portion 50 and the connecting member 45 in the transmission lever 44.

FIG. 8 shows an embodiment of the present invention. The configurations of these linkage mechanisms and adjustment means are different from those described above. In the figure, reference numeral 80 denotes a transmission, which is attached to the lifting frame. Reference numeral 81 denotes a support for the connecting element 45e, which is mounted on the frame 5e so as to be displaceable in the direction toward and away from the swing center of the driving lever 10e as indicated by an arrow. Reference numeral 82 denotes a long groove formed in the support body 81, which is formed to be long in a direction intersecting with the above-mentioned displacement direction, for example, in a direction perpendicular to the direction of displacement, and the long groove 82 is provided with a connecting element 45e to freely displace in the longitudinal direction of the groove. . Reference numeral 83 denotes a threaded rod in the adjusting means 12e, which is provided in a state oriented in a direction parallel to the displacement direction of the support body 81,
It is rotatably mounted on a support portion 84 provided in 5e, and is screwed into a screw hole 85 formed in the support body 81. Further, in this example, when the rotation angle of the drive shaft becomes approximately 190 °,
The displaceable direction of the connecting member 45e at 27e and the displaceable direction of the connecting member 45e at the connecting portion 50e match as shown in the drawing.

In such a construction, the transmission 80 moves up and down via the connecting member 45e by the swing of the driving lever 10e, and the needle bar 7e connected to it moves up and down. Loop sewing is performed as described above. Change the loop length with a screw rod
This is performed by rotating the 83 with the knob 83a. When the screw rod 83 rotates, the support body 81 is displaced in the direction of the arrow.
Then, the link 45e is displaced far and near with respect to the pivot point of the driving lever 10e. As a result, the vertical movement width of the transmission 80 is changed. In this case, since the displaceable direction of the link 45e in each of the link 27e and the link 50e is set to match the above case, the vertical movement width Re of the needle bar is set as shown in FIG. When changing, the bottom dead center position Le falls with the rise of the top dead center position Ue. And the rotation angle of the drive shaft is about 19
The position Pe of the hook portion of the hook at the time when it reaches 0 ° is a substantially constant position. As a result, even in the case of sewing a short loop or a long loop, the timing of the thread meeting the undercut of the hook is good, and the hooking is more reliable. Therefore, there is a feature that a longer loop can be formed than that described above. In addition, portions that are considered to have the same or equivalent configuration as those in the previous figure in terms of function are denoted by the same reference numerals as in the previous figure with the letter e, and redundant description is omitted.

[0023]

As described above, according to the present invention, the cloth 70 can be loop-stitched by the vertical movement of the needle bar 7e and the rotation of the looper 3, as a matter of course.

In the case of the above loop sewing, a long loop can be sewn by raising the top dead center of the needle bar 7e by the adjusting means 12e, and a short loop can be sewn by lowering the top dead center. This has the effect that a loop can be formed.

In addition, in the case of forming the above long loop or short loop, the lower dead center of the needle bar 7e is set lower as the upper dead point becomes higher. The thread 7 on the loop side to the undercut 17 at 15e
The timing of meeting 1 is constant both in a long loop and a short loop, and is not limited to the case where the sewing thread is a normal twisted yarn, but also the case where the sewing thread is a weakly twisted yarn. In addition to properly performing both the sewing of the short loop and the sewing of the short loop, there is a utility that a longer loop can be formed in forming a long loop.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a sewing machine.

FIG. 2 is a diagram illustrating a state of a linkage mechanism when a needle bar is at a top dead center.

FIG. 3 is a sectional view taken along line III-III in FIG. 1;

FIG. 4 is an explanatory diagram of the operation of the looper.

5A is a partial view showing a relationship between a hook and a thread, FIG. 5B is a sectional view showing a sewing state of a loop on a cloth, and FIG. 5C is a sectional view showing a sewing state of a loop on a cloth in a conventional example. FIG.

FIG. 6 is a diagram showing, by a line drawing, an operation relationship of the link mechanism in the case of changing the loop length.

FIG. 7A is a diagram showing a vertical movement range of a hook portion of a hook and a change state thereof in the present embodiment, and FIG. 7B is a diagram showing a similar state in a conventional example.

FIG. 8 is a partially broken partial view showing a different embodiment.

FIG. 9 is a diagram showing a state similar to FIG. 7A in the example of FIG. 8;

[Explanation of symbols]

 1 Needle plate 3 Looper 7 Needle bar 10 Drive lever 11 Linkage mechanism 12 Adjusting means 15 Hook needle U Top dead center L Bottom dead center R Vertical movement range

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) D05C 15/20 D05B 55/14 D05C 15/32

Claims (1)

(57) [Claims] 1. A vertically movable needle bar having a hook at a lower end is provided above a needle plate, and a rotatable looper is provided below the needle plate. A drive mechanism is connected to the needle bar and the looper, respectively. Thus, in a sewing machine in which the sewing on the cloth on the needle plate can be performed by the vertical movement of the needle bar and the rotation of the looper, the drive mechanism for the needle bar includes A linking mechanism for transmitting the swinging motion of the driving lever to the needle bar by changing it into a vertical motion, and the linking mechanism is provided with the rising of the top dead center of the needle bar. A sewing machine provided with adjusting means for changing the vertical movement width of the needle bar so as to sequentially lower the bottom dead center.