JPS5836999B2 - Needle thread cutting device for cycle stitch sewing machine - Google Patents

Description

[Detailed Description of the Invention] The invention of ζ relates to a cycle stitch sewing machine such as a buttonhole sewing machine, and in particular, the invention relates to a cycle stitch sewing machine such as a buttonhole sewing machine, and in particular, after a predetermined cycle stitch is completed, a movable blade disposed on a presser foot is moved forward by mechanical action. cuts the upper thread that traverses the needle path and continues between the stitch and the needle in cooperation with the fixed blade, and at a predetermined time after the start of the next stitch formation, the movable blade cuts the needle thread by elastic force. This invention relates to a cycle stitch sewing machine equipped with a thread cutting mechanism that moves backward.

A cycle stitch sewing machine equipped with this type of thread cutting mechanism is known from Japanese Patent Application Laid-open No. 54456/1983.

However, in such a thread cutting mechanism, after the movable blade and the fixed blade engage and cut the thread, the wear resistance between the movable blade and the fixed blade and the cutting of the thread caught between them Depending on the edge, etc., the movable blade may not be able to move back using only elastic force, and this may make it impossible to cut the thread when forming that stitch, or when starting to form the next stitch, such as on a buttonhole sewing machine. If the movable blade moves back when the movement area of the movable blade deviates from the needle path due to movement of the presser foot, the movement area of the movable blade returns to the needle path just before the end of stitch formation. At this point, there is a drawback that the movable blade may accidentally move back due to vibration of the sewing machine or some kind of impact force and collide with the needle, resulting in damage.

This invention prevents the above-mentioned drawbacks by applying mechanical acting force to the movable blade in the direction of backward movement when the movable blade does not move back due to an accident during the backward movement due to the elastic force. With the goal.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.The needle bar 2 is driven via a start/stop mechanism (not shown) when the sewing machine is started, and the needle bar 2 supporting the needle 1 at its lower end is driven by the start/stop mechanism (not shown).
moves up and down at a fixed position, and its horizontal amplitude and base line change, and a cloth feeding mechanism (described later) reciprocates the cloth in a direction perpendicular to the direction of needle vibration to form a buttonhole stitch. Alternatively, on the upper surface of the bed 3 of the cycle sewing machine that stops after this formation, the base of the feed arm 5 whose tip is bent along the lower surface of the arm 4 is moved to the first position in conjunction with the drive of the sewing machine.
, 2 is rotatably connected to a feed mechanism (not shown) that reciprocates left and right as shown in FIG. A cloth presser foot 7 having a long needle through hole 6 formed in parallel to the moving direction of the feed arm 5 is supported.

The presser foot 7 holds the fabric between itself and a fabric support (not shown) provided on the base 3, and reciprocates the fabric from side to side in conjunction with the cyclic operation of the sewing machine.

A guide frame 8 is provided at the tip of the feed arm 5 so as to form a guide hole parallel to the moving direction of the feed arm 5 between the tip and the upper end surface of the feed arm 5. A lifting rod 9 protruding downward from the top is supported in a vertically movable manner, and at the lower end of the lifting rod 9, a roller 10 that fits into the guide hole at the tip of the feed arm 5σ is rotated on one side. The supported branch piece 11 is fixed.

This sewing rod 9 is moved up and down via a lifting mechanism (not shown) in the sewing machine arm in conjunction with the operation of a foot pedal (not shown) appropriately placed below the sewing machine table (not shown). As it descends, the tip of the feed arm 5 is pressed downward via the rollers 10 and the presser foot 7 is pressed against the fabric support, and as it rises, the tip of the feed arm 5 is pushed downward via the rollers 10 and the guide frame 8. The tip portion is lifted up and the presser foot 7 is raised from the cloth support.

As shown in FIG. 2, on one side of the feed arm 5, the tip of a support plate 12 is placed in relation to a horizontal axis (not shown) placed on the lower surface of the arm of the sewing machine parallel to the direction of movement of the feed arm 5. A bent support rod 13 is fixed so that its lower end extends below the chin, and a core string guide 14 is attached to the lower end of this support rod 13, and a tubular core string guide 14 whose tip protrudes close to the needle.
will be established.

This support plate 12 is arranged so that the position of the core string guide 14 is changed when the base line of the amplitude of the needle 1 is changed and when the sewing direction is reversed so that the core string guide 14 always precedes the needle 1 in the sewing direction. The conversion mechanism is as described in the specification of Japanese Patent Application No. 1972-1972 filed by this applicant, and its explanation will be omitted here.

As shown in FIGS. 4 and 5, the presser foot 7 is provided with a cutting mechanism for cutting the needle thread and core string of the buttonhole seam.

Therefore, to explain this cutting mechanism, a blade part 15a is formed in an L shape so as to surround two sides of the left end of the rectangular needle through hole 6 of the presser foot 7, and is perpendicular to the moving direction VC of the feed arm 5. A fixed blade 15 provided with a blade part 15b along the moving direction is positioned so that the blade part 15a is located leaving a certain distance in the stitch progressing direction from the final needle drop point, and the blade part 15b is located at the blade part 15a.
The center part of a movable blade 16 formed in an L-shape is fixed to be closer to the needle drop point than the needle drop point, and the center part of the movable blade 16 formed in an L shape is supported rotatably by a step screw 17, and one end of the movable blade 16 is fixed so as to be closer to the needle drop point. By rotating the movable blade 16 clockwise, one side edge of the
A blade that traverses the path of the needle thread that connects the stitch formed on the fabric and the needle 1, that is, the path of the needle 1, captures the needle thread, and cuts it in cooperation with one blade portion 15a of the fixed blade. A blade part 19 is formed to cross the path of the core string connected to the part 18, the seam, and the core string guide 14, capture the core string, and cut the core string in cooperation with the blade part 15a. By rotating the movable blade 16 in the counterclockwise direction, the edge captures the cut ends of the upper thread and core string protruding from the seam ends formed in the cloth, and cooperates with the other blade part 15b of the fixed blade. A blade portion 20 is formed to cut the cut end short, and a pin 21 is implanted on the upper surface of the other end of the movable blade 16.

A movable blade 16 and a fixed blade 15 each extend above one blade part 15a of the fixed blade 15 at the front and rear ends of the left end of the presser foot 7.
Before the weft is cut between the blade part 15a of the movable blade 16
Clamp plate 2 for clamping it between the top surface of
2 and a clamp plate 23 for clamping the core string between the movable blade 16 and the body of the movable blade 16 before the core string is cut.

Next, the operating mechanism of the thread cutting mechanism will be explained.

As shown in FIGS. 1 and 3, a locking pin 24 is provided on the other side of the tip of the feed arm 5 and protrudes laterally on the upper surface of the tip, and the pin 21 of the movable blade 16 is attached to the lower edge of the tip. A movable plate 26 provided with a forked portion 25 for fitting is supported so as to be horizontally movable from side to side, and a spring-loaded pin 27 is provided near the rear end.
A coil spring 29 is stretched between the movable plate 26 and a spring hanging piece 28 provided at the extended end of the guide frame 8, so that an elastic force is always applied to the movable plate 26 to the right in FIG.

Above the movable plate 26, a locking piece 30 for locking the locking pin 24 is formed on the lower edge of the distal end with its right edge side inclined, and a cam portion 31 is formed on the finger and the lower edge of the middle. The rear end of the locking plate 32 is supported by a step screw 33 so as to be rotatable around a horizontal axis perpendicular to the moving direction of the feed arm 5, and a spring 34 wound around the step screw 33 always rotates the locking plate 32 clockwise. An engaging pin 35 is implanted on the lower end side surface of the branch 11 of the lifting rod 9 to apply a rotational force and to be able to engage with the cam portion 31.

A connecting shaft 3 is provided with a guide pin 37 that projects laterally slightly below the upper end of the transmission link 36 at the intermediate side of the feed arm 5.
8 rotatably supports the feed arm 5 about a horizontal axis perpendicular to the moving direction thereof, and its lower end and the rear end of the moving plate 26 are rotatably connected by intermediate links 39, respectively.

One end of a connecting link 40 is rotatably connected to the intermediate portion of the transmission link 36, and the other end of the connecting link 40 has an L-shape with the intermediate portion rotatably supported on the side surface of the rear end of the sending arm 5. It is rotatably connected to one end of the operating link 41 extending upwardly.

Although the other end of this operating link 41 is not shown,
It is linked to the elevating mechanism of the hoisting rod 9, and before the hoisting rod 9 is raised by lifting the hoisting rod 9 using the foot pedal, this operating link 41 is rotated counterclockwise and the lifting lever 9 is Rod 9
The rotation is released by the lowering operation.

A guide pin 37 of the connecting shaft 38 is provided on the side of the jaw of the sewing machine.
A cam plate 44 formed with a cam groove 42 into which the
Rotatably supports one end of.

The present invention has the above configuration, and its operation will be explained next.

The state shown in FIG. 1 shows the state in which the seam formation has been completed, and at this time, the movable plate 26 is positioned to the right by the action of the coil spring 29, and the locking pin 24 is the locking piece of the locking plate 32. 30, and the engaging pin 3 of the branch 11 of the bar 9
5 is located away from the cam portion 31 of the locking plate 32 to the right, and the guide pin 37 of the connecting shaft 38 is located in the cam groove 4 of the cam plate 44.
It is located near the left end of 2.

In this state, if the lifting rod 9 is raised using the foot pedal, the operating link 41 is rotated counterclockwise at the initial stage of the operation, and the transmission link 36 is thereby connected to the connecting shaft 38 via the connecting link 40. The movable plate 26 is rotated clockwise around , and the movable plate 26 is moved to the left via the intermediate link 39 against the action of the coil spring 29.

Due to this movement of the moving plate 26, the locking pin 24 engages with the right edge of the locking piece 30 of the locking plate 32, and the locking plate 32 is pushed out counterclockwise against the action of the spring 34 and engaged. After the stop piece 30 moves to the left, the stop plate 32 rotates back clockwise due to the action of the spring 34, and at the same time, the rotation of the operating link 410 is stopped.

This movement of the movable plate 26 causes the forked portion 25 and the pin 2 to
1, the movable blade 16 is rotated clockwise in FIG.
One blade part 18 on one side edge captures the needle thread T that continues from the final needle drop point of the stitch formed on the cloth to the needle, and the other blade part 1
9 captures the core string S connected from the seam to the core string guide 14, and then clamps the needle thread T and the core string S between the lower surfaces of the clamp plates 22 and 23 and the upper surface of the movable blade 16, respectively, and
Each blade part 1B. 19 and one blade part 15a of the fixed blade 15 to cut the weft thread T and the core string S (see Figure A in Figure 7).
.

Therefore, when a new cloth is inserted into the lower surface of the presser foot 7 and the lifting rod 9 is lowered to form the next stitch, the rotation of the operating link 410 is released, but the moving plate 26 is Since the locking pin 24 is locked by the left edge of the locking piece 30 of the locking plate 32, it does not return to the right, and the movable blade 16 is maintained in the state shown in FIG. 7A.

When the sewing machine is driven, the feed arm 5 moves to the right in Figs. 1 and 6 (left in Fig. 2.5.7), and moves the core string from near the final needle drop point to the right. The stitch shape progresses as the S is sewn in.

When the needle drop point reaches outside the rotation area of the movable blade 16 as the stitch formation progresses, as shown in Fig. B of Fig. 7, the locking plate 32 is moved as shown in Fig. B of Fig. 6. The cam part 31 is the branch 1
The locking plate 32 is engaged with the first engagement pin 35 and the locking plate 32 is again pressed against the spring 34.
As a result, the locking pin 24 of the movable plate 26 is released from the locking pin 24 of the movable plate 26 by the locking piece 30, and the movable plate 26 returns to the right by the action of the coil spring 29. The movable blade 1
6 is moved back in the counterclockwise direction, and this back movement causes B in FIG.
As shown in the figure, the cut end of the clamped upper thread T and the cut end of the core string S are connected between the blade part 20 on the other side edge of the movable blade 16 and the other blade part 15b of the fixed blade 15. cut short.

Note that when the locking pin 24 is released by the locking piece 30, the blade portions 15a of the movable blade 16 and the fixed blade 15, the clamp plate 22,
If the movable plate 26 does not return due to the force of the coil spring 29 due to frictional resistance between the moving plate 26 and the cam plate 23, the upper front end of the transmission link 36 will engage the pressing pin 43 of the cam plate 44 due to further movement of the feed arm 5 after the above-mentioned release. As a result, the transmission link 36 is forcibly rotated counterclockwise by the pressing pin 43, and the movable blade 16 is reliably rotated by this rotational force and the acting force of the coil spring 29. Returned.

Then, as shown in Fig. 6C, the subsequent feeding arm 5
As a result of this movement, the cam plate 44 is rotated clockwise while being guided by the guide pin 37 of the connecting shaft 38, and the suppressing pin 43 is moved to a position out of engagement with the upper end of the transmission link 36.

In this case, when the thickness of the cloth to be sewn changes, the position of the tip of the feed arm 5 changes in the vertical direction via the cloth presser foot 7, but the cam plate 44 also changes via the guide pin 37 of the connecting shaft 38. The suppression pin 43 is rotated following the change, and the feed arm 5
It changes vertically in response to the vertical change of the transmission link 36 due to the vertical change of The forced return timing of the blade 16 can always be kept constant.

Therefore, when the feed arm 5 reaches the rightmost position and the sewing on one side of the buttonhole stitch is completed, one side of the bar tacking is performed, and then the base line of the needle bar 2 is changed and at the same time The moving direction of the feed arm 5 is reversed and moved to the left in Figures 1 and 6 (to the right in Figures 2, 5, and 7), and the other side sewing is performed, and the feed arm 5 moves to the original. When it has almost returned to its position, the other bar tacking is performed, the buttonhole stitch is completed, and the sewing machine stops.

After this stop, the lifting lever 9 is raised, and as described above, the upper thread T is connected to the final needle drop point of the stitch and the needle 1, and the core is connected to the end of the stitch and the core string guide 14. String S is movable blade 1
It is cut by the forward movement of 6.

As described above, this invention traverses the path of the needle and fixes the thread connected between the stitch and the needle by the reciprocation of the movable blade disposed on the presser foot or mechanical action after the completion of a predetermined cycle stitch. In a cycle sewing machine equipped with a thread cutting mechanism in which thread cutting is performed in cooperation with a thread cutting blade, and the movable blade moves back due to elastic force at a predetermined time after the start of the next stitch formation, the return of the movable blade is When the movable blade does not move back at the specified time, the movable blade is forcibly returned to its original position via the rotating transmission body due to the suppressing action of the suppressing part of the cam plate. Since the movable blade can be returned to its original position at the same time, the needle thread can be reliably cut when the stitch formation is completed.Especially, when the sewing machine starts to form the next stitch, as in the case of a buttonhole sewing machine, the needle thread can be reliably cut. If this is applied to a sewing machine in which the movable blade moves backward when the moving area of the movable blade deviates from the path of the needle due to the movement of Since the movable blade can be prevented from making an accidental return movement when it returns to the path, it is possible to prevent an accident in which the movable blade collides with the needle and causes damage, resulting in an excellent safety effect.

In addition, when the thickness of the cloth pressed by the presser foot changes, the vertical position of the tip of the feed arm changes, and the transmission body also displaces vertically, but the vertical displacement of the tip of the feed arm also changes. Since the pressing part of the cam plate is also moved up and down in conjunction with the movement, there is no change in the opposing relationship between the other end of the transmission body and the suppressing part, and the pressing timing of the movable blade can be changed.
In other words, the forced return timing can always be kept constant, and when the transmission body is displaced toward the ground, the suppressing portion engages with the intermediate portion of the transmission body, thereby preventing the movement of the feed arm and preventing the feed mechanism from moving. Accidents such as breakage can be prevented from occurring, and there are effects such as excellent safety.

[Brief explanation of the drawing]

Figure 1 is a left side view of the sewing machine, Figure 2 is a right side view of the sewing machine, Figure 3 is a perspective view showing the operating mechanism of the thread cutting mechanism, and Figure 4 is the presser foot mechanism and the thread cutting mechanism installed therein. FIG. 5 is a top view of the presser mechanism, FIG. 6 is an explanatory diagram showing the operating order of the thread cutting mechanism, and FIG. 7 corresponds to FIG. 5, and the operating order of the thread cutting mechanism. FIG.

Claims (1)

[Claims] 1. A cycle stitch sewing machine that is driven by a starting operation and stops after forming cycle stitches consisting of a fixed number of stitches,
A feed arm 5 that can reciprocate along the bed surface in conjunction with the drive of the sewing machine and whose tip can move up and down with respect to the bed surface, and a feed arm 5 that is supported at the tip of the feed arm and presses and releases the cloth by vertical movement of the feed arm. A cloth presser foot 7 that can move the cloth along the bed surface as the feeding arm moves during pressing; A movable blade 16 is supported on a presser foot so as to be able to reciprocate across the board, and a movable plate 26 is supported on the side surface of the tip end of the feed arm so as to be reciprocally slidable and has one end connected to the movable blade and has a locking pin 24. , a spring 29 stretched between the movable plate and the end of the feed arm, link mechanisms 40 and 41 whose one end is rotatably connected to a transmission link and the other end is connected to an operating mechanism such as a pedal; It is movably supported and has a retaining pin 35 at the lower end.
A lifting rod 9 is provided and connected to the presser foot, and a locking piece 30 whose base is rotatably supported on the side surface of the presser arm and which faces the locking pin of the movable plate at the free end and a locking rod 9 is connected to the pressing rod. A locking plate 32 formed with a cam portion 31 facing the coupling pin, a suppressing pin 43 facing the upper end surface of the transmission link whose base is rotatably supported on an arm, and loosely fitting into the connecting shaft of the transmission link. A cam plate 44 having a cam groove 42 formed therein, and an operation of the operating mechanism when the sewing machine is stopped moves the moving plate 26 in one direction via the link mechanisms 40, 41 and the transmission link 36 to move the movable blade. At the same time, the locking piece 30 and the locking pin 24 are engaged to lock the moving plate in the forward movement position of the movable blade, and the next sewing machine is started. When the presser arm moves forward, the cam portion of the locking plate engages with the locking pin of the lifting rod, and the locking pin is released from the locking piece, allowing the moving plate to move forward due to the spring. When the movable plate does not move back due to the above spring due to the subsequent forward movement of the presser arm, the upper end of the transmission link is brought into contact with the pressing pin of the cam plate, the transmission link is rotated, and the movable plate is moved in the opposite direction. The needle thread cutting mechanism of a cycle stitch sewing machine has various parts related to each other so that the blade moves back and forth.