JPS6058150B2 - Binding wire supply method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a binding wire supply method and apparatus for a binding machine.

In particular, the present invention relates to a method and apparatus for automatically supplying a binding wire before winding the wire around a winding hobbin. First, a binding machine incorporating the binding wire supply method and device of the present invention will be explained.

Six winding bobbins 210 are mounted equidistantly on a rotatable turret disk 1, and a wire binding device 4, a wire hooking device 5, a bobbin drive device ( (not shown), a binding device 7, a terminal processing device 8, and a roll take-out device 9 are provided.

When a plurality of binding wires 400 for binding windings are sequentially attached by the binding wire supplying device 4 to one of the winding bobbins 210 provided on the turret disk 1 which is stopped at a predetermined position, the turret disk 1 rotates by a predetermined angle, and at the same time, the winding bobbin 210 moves to the wire hooking position, the wire hooking device 5 and the bobbin drive device hook the winding bobbin, and the wire rod 50 of a predetermined length is attached to the bobbin. It is wound and then bent and cut. The winding bobbin 210 on which the wire rod 50 has been wound as described above is sent to the next binding position as the turret disc 1 rotates, and at this position, the binding device 7 winds the wire onto the bobbin, and the wound wire is wound at multiple locations. The wires are sequentially bundled with binding wires, and then sent to the terminal processing position, where the terminal processing device 8 sequentially processes the ends of the plurality of binding wires and one winding, thereby processing the wound wire. After completion of the winding process, further rotation of the turret disk 1 causes the winding bobbin to be sent to the winding object take-out position, and the winding object is taken out from the winding bobbin by the winding object take-out device 9 and transferred to the belt conveyor 910. placed on top. As described above, the wire binding device of the present invention constitutes the first step in a series of steps of the binding machine.

Conventionally, binding wire to a winding bobbin has been either automatically supplied after the wire has been wound on the bobbin, or mainly manually when it has been done before the wire is wound on the bobbin. It was extremely inefficient.

The present invention aims to eliminate the above-mentioned deficiencies.

First, the configuration of the present invention will be explained based on the accompanying drawings. The bundled wire supply device of the present invention is composed of 1 a bundled wire cutting section, 2 a bundled wire pull-out section, 3 a bundled wire holding section, 4 a bundled wire push-in section, and 5 an index fixing section, all of which include a cam device as a common part. There is.

These configurations will be explained below.

The binding wire 400 is pulled out from the supply bobbin 401 and guided directly below the take-up bobbin 210 through the adjustment roller group 402. An adjustment table 403 is provided close to the supply bobbin 401, and the adjustment roller group 40 is mounted on the adjustment table 403.
In addition to 2, a guide flock 404 and a cutting device 405 are installed.

The cutting device 405 is driven by a cam 406 and consists of two bladed levers 407 and 408 that cross the path of the binding wire 400 on the front surface of the guide block 404, and the bladed levers 407 and 408 are, respectively, Its legs are connected to rotating shafts 409, 410.

The rotation shafts 409 and 410 are each rotatably mounted on a frame 411 on the adjustment table 403. Further, the guide block 404 is also fixed on the frame 411. Gears 412 and 413 having the same pitch circle are fixed to the ends of rotating shafts 409 and 410, and both gears mesh with each other. A lever 414 is fixed to the other end of one rotating shaft 409. To open and close the cutting device 405, a cam 406 pivotally supported by the frame 0 is used (the rotational drive device for the cam is omitted).

The cam 406 includes cams 441, 471, and 4, which will be explained in sequence below.
39 is mounted on a common camshaft 418. The lever 415 that is in contact with the outer periphery of the cam 406 is
One end of the cam 406 is hinged to the frame 0, and is always biased by a spring 416 so as not to separate from the surface of the cam 406. The tips of the levers 414 and 415 are hingedly connected by a rod 417. Kamreba 4
15 is a cam follower 415″ that is in contact with the cam 406
will be established. Next, a gripper for grasping and pulling out the cut end of the binding wire 400 and its driving device, that is, a drawing device will be explained.

The drawing device 420 has the following structure.

The slide base 421 has a link mechanism gripper 422 and a cylinder 423 installed on its upper part. A gripper 422 disposed below the winding bobbin 210 in its axial direction is attached to the side of the end binding wire supply bobbin 401 of the slide base 421, and is connected to a pair of fixing pins 426 provided on the slide base 421 and Pin i: A pair of open/close links 424 rotatably attached, one end of each of which is rotatably connected to the open/close link with a pair of pins 426'', and the other ends are mutually rotatable with a pin 428. a pair of interlocking links 427 connected to the pin 4;
28, and the middle part is rotatably connected to the slide base 4.
A pair of guide blocks 43 attached to the top of 21
0 and an opening/closing rod 429 that is slidably supported. Further, the tip of the cylinder rod 434 of the cylinder 423 and the rear end of the opening/closing rod 429 are connected with a pin.

Therefore, as the cylinder rod 423 expands and contracts, the tip 425 of the opening/closing link 424 is opened and closed, and the end of the binding wire 400 can be grasped or released. At the lower part of the slide base 421, a front block 431 is attached to the front part, a rear brake link 432 is attached to the rear part, and two slide rods 433 having a circular cross section are attached in parallel between them.

The slide rod 433 penetrates into a rod guide block 434 attached to the frame 0 and can slide back and forth. A shaft 435 is fixed to the lower part of the frame 0, and a swing lever 436 is swingably attached to this shaft.

The swing lever 436 is urged by a spring or the like (not shown) so as to be pressed against the outer periphery of another cam 439 attached to the camshaft 418 described above. What actually comes into contact with the outer periphery of the cam is a roll follower 437 attached to the middle part of the swing lever 436, which contacts the cam shaft 418.
The swing lever 436 swings via the cam 439 and the follower 437 due to the rotation of the swing lever 436 . The tip of the swing lever 436 and the lower part of the rear block 432 are hingedly connected via a connecting rod 438.

The cutting device 405 and the pulling device 420 described so far have two cams 406 and 43 attached to a common camshaft 418.
9, two cams 441 and 471 are further attached to the shaft 418 in parallel. Further, two swing levers 443 and 473 are rotatably attached to a common support shaft 444 fixed to the frame 0, and a cam follower 44 is installed in the middle of each swing lever.
2,472, and these cam followers are in contact with the outer peripheral surfaces of the cams 441, 471, respectively.

Each of the above-mentioned levers is biased by a respective spring means (not shown) so that the cam surface and the cam follower maintain contact. The binding wire holding device 440 has a pair of opening/closing wings 448 whose tip portions have a shape that almost matches the inner profile of the winding bobbin 210, and the lower part of the opening/closing wings is connected to a pair of parallel shafts 4, respectively.
It is fixed at 49.

The pair of shafts 449 are each rotatably supported by a pair of support blocks 447 fixed to the frame 0, and a spur gear 450 having the same number of teeth is attached to one end of each shaft so as to be meshable. One end of the opening/closing lever 446 is attached to the other end of one shaft 449. Also, opening/closing lever 446
The other end and the tip of the swing lever 443 are the intermediate rod 4
They are hinged together via 45. The binding wire pushing plate 470 is guided at its outer side by six grooved guide rollers 474 rotatably supported by the frame 0, so that it can slide up and down.

The upper tip 47' of the pushing plate 470 has almost the same shape as the inner surface profile of the winding bobbin 210 like the opening/closing blade 448 described above, and can open/close so as to pass through the gap between the pair of shafts 449 of the opening/closing blade 448. It is installed between the wings 448.

In addition, the lower part of the push plate 470 and the swing lever 473
is hinged to the distal end of the intermediate shaft 475. Next, the structure of the index fixing device 320 at the wire binding supply position and the structure of members related thereto will be explained.

As mentioned above, there are winding bobbins in the disc bracket 11 at three locations, the two adjacent positions and the farthest position when viewed from the winding position, that is, the binding wire supply position 4, the binding position 7, and the terminal processing position 8. An indexer is provided for rotation by 113 increments and a fixing device is provided to prevent the rotation. The disk bracket 11 is provided with an L-shaped bracket 321, and a block 322 is attached to the tip thereof.

A through shaft 323 and a shaft 324 are rotatably supported in the block 322 by a pair of bearings 325 and 326, respectively. A small gear 327 that meshes with a large gear 328 is provided at the tip of the through shaft 323. Also, the large gear 328 has lever 3.
A notch 330 is provided at the tip of this lever 329, and a transmission pin 331 attached to the plate cam 14 is fitted into the notch 330.

Further, a swinging lever 333 having a protrusion 332 at its tip is fixed to the opposite side of the small gear 327 of the through shaft 323, and can swing around a pin 335 provided at the tip of the swinging lever 333. A hook 338 is attached to the distal end of the attached latch 334, and the rear end of the hook 338 abuts a pin 336 erected on the swing lever. A spring 337 is tensionably provided between the intermediate portion of the latch 334 and the protrusion 332 of the swing lever. Also, the bracket 33 attached to the disc bracket 11
9 is provided with a pin 340.

A stop lever 341 having a protrusion 342 at its tip is rotatably attached to this pin 340. A roller 343 rotatably attached to the rear end of the stop prepper 341 is brought into contact with the concave surface of the plate cam.
A torsion spring 344 is attached between the bracket 339 and the stop lever 341 so as to surround the pin 340, and urges the stop lever in the direction of arrow A in FIG. The bracket 10 provided on the outside of the drive shaft 310 of the turret disc 1 has a disc bracket 11 on a plane orthogonal to the turret axis, corresponding to the position where the first flange 272 provided on the control section 270 is normally located. is fixed to form a A ring-shaped auxiliary bracket 12 having the same outer diameter as the disc bracket 11 is attached to the disc bracket via a ring spacer 39. The first
Movement of the flange 272 in the axial direction is restricted. In addition to the auxiliary bracket 12, three first columnar brackets 13 and three second columnar brackets 15 are each installed on the disk bracket 11 at equal distances from the center line of the turret disk drive shaft 310. The first bracket 15 is shorter in length than the second columnar bracket. Both brackets have donut-shaped plate cams 16 and 14 in guide grooves 38 and 14, respectively.
37, it is held rotatably. Also plate cam 16
, 14 are attached to the main body frame 0. The cylinders 24, 23 are swingably attached to the common bracket 40.
The pins 28 and 27 are hinged to pieces 30 and 29 provided at the ends of the rods 26 and 25, respectively. The rotating shaft 251 of the winding bobbin is attached to one end of the winding bobbin.
A control section 270 is installed at the other end of the bobbin 210, and an intermediate section thereof is rotatably supported by a bearing section 250. Control unit 2
To explain the configuration of 70, a first flange 272 and a second flange 273 are provided on both sides of a roller 271, and the first flange 272 has three flared ends at positions that equally divide the circumference of the outer diameter part into three parts. A triangular notch 276 is provided.

Further, roll pins 277 are rotatably provided on the second flange 273 at positions dividing the circumference of the side surface into three equal parts. Also, three triangular notches 278 are provided on the outer periphery of the second flange 277 on the outside of the roll pin.

Next, the structure of the winding bobbin 210 to which the binding wire is supplied by the apparatus of the present invention will be described.

The winding bobbin has a small flange 211, a large flange 213,
It consists of a cylindrical portion 215 that forms a connecting portion between these parts.

Three holes 233 are bored in the blade 220 of the large flange 213 at points equally divided into three on the same circumference, and the center axis of these holes is parallel to the center axis of the bobbin. A shallow groove 234a with a narrow width is located on the line of intersection between the surface formed by the cylindrical portion 215, small flange 211, and large flange 213 of the winding bobbin and three half planes including the center axis of the hole 233 and the bobbin center axis. , 234b, and 234c are continuously drilled from the outermost part of the small flange 211 to the outermost part of the large flange 213.Therefore, the grooves 234 are provided radially at three locations each on the large and small flanges, and three grooves are provided on each of the large and small flanges. One location is also provided on each curved surface portion 216 of the divided cylindrical portion 215. Therefore, when the small flange 211, the cylindrical portion 215, and the large flange 213 are combined to form the winding bobbin 210, three continuous grooves 234a, 234b, and 234c are formed at equal intervals on the inner peripheral surface of the winding bobbin. is formed. Further, the cylindrical portion 215 has grooves 237 whose widths are unequally spaced from each other in the curved surface portion 21.
6. These grooves 237a, 237b, 23
7c serves to hook the end of the winding wire when it begins to wind on the winding bobbin. Further, the groove 234 is used to push the binding wire 400 in and lock the binding wire using the device of the present invention. The operation of the wire binding device of the present invention will be explained in relation to the wire binding step.

The binding wire 400 wound around the supply bobbin 401 is manually pulled out in advance, passes between the adjustment roller 402 and the guide block 404, and when it reaches the cutting device with the blade levers 407 and 408 open. When the feeding device of the present invention is operated, the cam 439 attached to the camshaft 418 comes into contact with the cam follower 437 provided on the swing arm 436 as the camshaft rotates, so that the swing arm rotates around the shaft 435. Since it moves to the left (toward FIG. 4), it passes through the connecting rod 438 and the rear block 432.
A slide bar 433 connected to the swing bar 436 slides to the left (toward FIG. 4) within a slide block 434, and is connected to a front block 431 and a rear block 432 at the end of the slide bar. It moves in the same direction together with the slide base 421. At the same time, the gripper 422 provided on the slide base 421 also moves in the same direction, and the end of the binding wire 400 that has reached the cutting device 405 as described above is connected to the tip of the pair of opening/closing links 424 of the gripper 422. When the portion 425 closes, it is held by the gripper 422. The opening/closing link tip 425 is opened/closed by the opening/closing rod 429 sliding back and forth within a guide block 430 provided on the slide base 421 by the operation of the cylinder 423. When the binding wire 400 is clamped by the tip 425 of the gripper 422, the swing bar 436 is moved in the opposite direction (toward the right in FIG. 4) about the shaft 435 due to the contact between the cam 439 and the follower 437. and swing lever 4.
Since the related member connected to 36 is moved rightward, the binding wire 400 is pulled out from the supply bobbin 401 and placed under the winding bobbin 210 under tension.

In this state, the cutting device 405 and the opening/closing holding device 440 are in an open state, and the pushing plate 470 is located below the opening/closing holding device 440. (See Figure 4)
. Next, the opening/closing holding device 440 in the open state is closed and the binding wire 400 is held. When the other swing lever 443 is pushed upward about the support shaft 444 due to the contact between the rotating cam 441 and the cam follower 442, the other swing lever 443 opens and closes as well as the intermediate rod 445 connected to this swing lever 443 at its end. Since the pair of shafts 449 are rotated via the opening/closing lever 446 connected to the shaft 449 of the holding device 440, the pair of spur gears 450 attached to the ends of these shafts mesh with each other.
Since they rotate in opposite directions, the pair of opening/closing wings 448 of the opening/closing holding device are brought into a closed state, and the binding wire 400 is held on both inner surfaces thereof. Next, the blade levers 407 and 408 of the cutting device 405 are moved inwardly (towards FIG. 2B).
It is activated to shear one end of the binding wire held by the opening/closing wing 448 of the opening/closing holding device as described above.

The shearing operation is performed as follows.

As the shaft 418 rotates, the cam 406 attached to the camshaft 418 comes into contact with the cam follower 415'' provided on the lever 415 and pushes the lever 415 upward. This upward movement causes the rod 417 and the lever 414 to move upward. rotating shaft 4 through
09, and the gear 412 provided at the end of this rotating shaft 409 and the other rotating shaft 410
The gear 413 provided at the end of the shaft rotates in directions opposite to each other. Therefore, the pair of bladed levers 407 and 408 attached to the pair of rotating shafts 409 and 410 operate inward, shearing the binding wire 400.

When the shearing operation is completed, the swing lever 473 interlocked with the pusher plate 470 is pushed upward about the support shaft 444 due to contact between the cam 471 and the cam follower 472, and the pusher plate 470 moves toward the guide 474.
The binding wire 400, one end of which is clamped by the gripper 422, is pushed up by the upper end 47'' of the plate, and the binding wire is wound up to the small flange 211 of the bobbin 210, the cylindrical portion 215, It is pushed into a groove, for example 234a, connected to the large flange 213 from below. The pushed-in binding wire is locked in the groove in the shape of an irises. Just before the cut binding wire 400 is pushed into the groove by the pushing plate 470, the gripper 442 of the pulling device 420 moves the opening/closing link tip 425 by the forward movement of the opening/closing rod 429.
opens, and the clamping of the binding wire 400 is released.

As the swing lever 473 descends, the push-in plate 470 repeats the opposite movement to the above-mentioned upward movement and returns downward to its original position.

Furthermore, the opening/closing wing 448 of the opening/closing holding device and the swing lever 443
The lowering movement causes the opening/closing lever 446 to be lowered via the intermediate rod 445, so that the opening/closing lever 446 repeats the opposite movement to the upward movement and returns to the original open state.

The binding wire 400 cut to a certain length in this manner is locked in a continuous groove, for example 234a, of the winding bobbin 210 in an irises shape.

When the above series of operations is completed, the winding bobbin is rotated by a predetermined angle by the action of a separately provided indexing and fixing device.
Furthermore, a new continuous groove, for example, 234b opening/closing holding device 440
Since the binding wire 400 is moved to the upper position, the binding device can supply the binding wire 400 to this new continuous groove 234b in the same manner as described above.

Next, the binding wires are sequentially supplied to the remaining continuous grooves 234c in the same manner, thereby completing the action of supplying the binding wires to all the winding bobbins.
The operation of the indexing and fixing device for the winding bobbin 210 is as follows.

First, the rocking motion of the plate cams 16, 14 will be explained.

The cylinders 24 and 23 erected on the bracket 40 provided on the frame operate, and the rods 26 and 23 connected to them operate.
When the cams 25 are moved up and down, respectively, the plate cams 16 and 14 swing at a predetermined angle via the pieces 28 and 27 which are pivotally attached to the pieces 30 and 29 at the tip of the rod. As the tip plate cam 14 moves to the left (toward FIG. 11), the notch 3
A lever 329 fitted at 30 rotates, and a large gear 328 fixed to this lever via a shaft 324 rotates. When the small gear 327 fixed to one end of the through shaft 323 meshes with the large gear 328 and rotates in the opposite direction, the swing lever 333 attached to the other end of the through shaft 323 also rotates in the same direction. 323 as the center, so as the swinging lever 333 rotates, the hook 338 pivoted to the pin 335 of this lever also moves upward (toward FIG. 11) while being supported by the spring 337. It is pushed up, and its hook 338 is hooked onto one of the three roll pins 277 erected on the second flange 273 of the control device located at the upper position. Next, when the plate cam 14 moves in the opposite direction, that is, to the right, the related members return to their original positions due to an action completely opposite to that described above.

Therefore, the hook 338 returns to its original position while hooking one of the roll pins 277, and together with the roll pin 277, the control unit 270 is rotated by a predetermined angle (1200 degrees in this embodiment). , the control section 270 sequentially and intermittently rotates by the number of roll pins 277 (three times in this embodiment). Therefore, the winding bobbin 210 connected to the control section 270 via the shaft 251 also rotates intermittently. The winding bobbin is rotated intermittently in the same direction by a predetermined angle.As described above, before the control unit rotates the winding bobbin by a predetermined angle, the control unit 270 uses an indexing device to lock the winding bobbin at a predetermined position. is necessary.

This purpose is to prevent the stopper 3 from sliding on the uneven surface of the cam 16.
This is achieved by 41. That is, before the cam 14 makes a swinging motion and the hook 338 is hooked on the roll pin 227, another cam 16 moves to the left (toward FIG. 8).
When the roller 343 of the stopper 341 moves, the cam 16
Since the stop 341 rides on the convex surface rather than the concave surface of the stop 341, the stop 341 rises upward with the pin 340 as the center, working together with the action of the torsion spring 344 wound around the pin 340 and biased in the direction A. The protrusion 342 is the second
It engages with one of the three grooves 278 bored in the outer circumferential surface of the second flange so as to be located outside of the roll pin 2774 erected on the flange 273, thereby regulating the rotation of the second flange. Therefore, through this regulation, the winding bobbin 210 can be stopped at a fixed position. Stopper 341 to the groove 278
The locked state of the protrusion 342 continues until the hook 338 of the swing lever 333 rises to the position of one of the roll pins 277 and is hooked on this pin due to the swing of the cam 14 as described above.

When the plate cam 16 is then moved to the right, the roller 343 of the stopper 341 moves onto the concave surface of the cam 16, and the stopper 341 tilts downward against the elastic force of the torsion spring 344. (See FIG. 12) The protrusion 342 of the stopper 341 comes out of the groove 278.

According to the apparatus and method of the present invention, an appropriate number of binding wires can be automatically supplied to the winding bobbin before winding the wire rod, and unlike the conventional example, the wire rod is wound around the winding bobbin. Compared to the method of tying these together afterwards, this method allows the tying work to be performed easily and quickly using a tying wire, and has the effect of eliminating inefficient work such as manual work.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate embodiments of the invention.

Fig. 1 is a front view of the binding machine of the present invention, Fig. 2A is a side view of the cutting device, Fig. 2B is a front view of the cutting device, Fig. 3 is a detailed partial view of the cutting device, and Fig. 4 is a bundling device. FIG. 3 is a side view of a wire drawing device, a wire binding device, and a wire binding device. Fig. 5 is a plan view of the gripper of the wire binding device as seen in the direction of arrow A in Fig. 4, Fig. 6 is a side view showing a partial cross section of Fig. 5, and Fig. 7 is B in Fig. 5. 8 is a front view of the wire binding device, and FIG. 9 is a front view of the wire binding device and the pushing device. FIG. 10A is a detailed cross-sectional view of the index fixing device;
Figure B is a front view of the second flange of the control unit, Figure 11 is a route map of the rotation indexing part, Figure 12 is a route map of the rotation regulating part, and Figure 1 is a route map of the rotation regulating part.
3A is a side view of the winding bobbin, FIG. 3B is a front view, and FIG. 3C is a partial view of the large flange cylindrical portion. 0 is a frame, 2 is a turret disk, 4 is a binding wire supply device, 5 is a wire hooking device, 8 is a terminal processing device, 9 is a winding material take-out device, 10 is a cylinder bracket, 11 is a disk bracket, 14, 16 is a plate cam, 210 is a winding bobbin, 211 is a small flange, 213
215 is a large flange, 215 is a cylindrical portion, 234 is a continuous groove, 23
7 is a groove, 270 is a control section, 272 is a first flange, 27
3 is a second flange, 277 is a roll pin, 278 is a notch, 320 is an index fixing device, 327 is a small gear, 328
is a large gear, 329 is a lever, 332 is a protrusion, 333 is a swinging lever, 341 is a stopper, 400 is a binding wire, 405 is a cutting device, 407, 408 are bladed levers, 409 is a shaft, 414, 415 are levers, 417 is a rod, 420 is a drawing device, 422 is a gripper, 423 is a cylinder, 43
3 is a slide block, 436 is a swing lever, 440
443 is a swing lever, 445 is a handle, 446 is an opening/closing lever, 448 is an opening/closing wing, 449 is a shaft, 470 is a push plate, 473 is a swing lever, 474 is a guide roller, and 475 is an intermediate shaft.

Claims (1)

[Scope of Claims] 1. In an apparatus for forming a winding material on a winding bobbin and tying it at a plurality of places, when supplying a binding wire for binding the wire material in advance before winding the wire material on the winding bobbin, The binding wire that has been pulled out from the bobbin and cut to a certain length is wound up and held in a holding device that is arranged so as to face one of the multiple grooves that are continuously formed in the axial direction on the inner peripheral surface of the bobbin. Then, a pushing plate that is slidably attached to this holding device and has a tip having the same shape as the continuous groove formed on the inner circumferential surface of the bobbin is advanced, and the binding wire is inserted into the groove with the tip. A method for supplying a binding wire, characterized in that the wire is pushed in, and then the take-up bobbin is rotated to expose another adjacent groove to the position of the holding device. 2. In a device in which a winding bobbin winds a wire to form a wound wire, and before the winding bobbin is bound at a plurality of locations, the wire is supplied to the winding bobbin in advance. The tip is wound around a pair of shafts connected to the drive lever mechanism. A binding wire holding device is provided with a pair of opening/closing blades rotatably mounted in a shape substantially matching the inner profile of the take-up bobbin, and the opening/closing blades are provided close to the inner circumferential surface of the take-up bobbin; A pushing plate having the same shape as the tip of the opening/closing blade slides up and down in the gap between the pair of opening/closing blades, and in its raised position, a plurality of continuous plates are formed on the inner surface of the winding bobbin at equal angles from the center of rotation of the bobbin. a drive lever mechanism that is actuated to engage the groove;
A binding wire supply device comprising a binding wire pushing device having a binding wire supply position indexing device using a ratchet mechanism that rotates the bobbin intermittently by an angle formed by one of the continuous grooves and an adjacent groove.