JP4707489B2 - Sewing hook mechanism - Google Patents

Description

  The present invention relates to a shuttle mechanism for a sewing machine in which an inner shuttle reciprocates.

A conventional sewing machine that performs main sewing is provided with a thread trimming device below the needle plate of the sewing machine bed, and further provided with a hook mechanism for entwining the lower thread with the upper thread below the thread trimming device. ing.
The hook mechanism is arranged on the bobbin case for storing the bobbin of the bobbin thread, the inner hook that reciprocates around the bobbin case, the cauldron that holds the inner hook so as to be reciprocatingly supported, and the upper part of the cauldron (For example, refer to Patent Document 1).

  In the hook mechanism, when the sewing needle descends inside the guide hole of the thread guide plate during sewing, the sword tip provided in the center hook catches the upper thread, and the loop of the upper thread is moved below the inner hook. Extend to. When the hook is rotated to a position where the sword tip slightly passes just below the hook, the rotation is switched in the reverse direction, and the upper thread is released from the captured state. When the upper thread is pulled by the balance at this timing, the upper thread loop is pulled up through the inner hook. As a result, the lower thread fed out from the bobbin case located inside the inner hook passes through the loop of the upper thread, thereby forming a knot and performing sewing.

On the other hand, the thread guide plate is formed with a guide hole through which the upper thread and the lower thread are inserted during sewing, and the guide hole is formed when the loop of the upper thread is extended downward by the inner hook. The upstream portion and the downstream portion are pushed open across the upper thread sword tip. In other words, this allows the loop to be formed without the upper thread being pinched between the intermediate hook and the cauldron.
Further, the yarn guide plate is formed with a lower yarn holding portion for holding an end portion of the lower yarn cut by the yarn cutting device.
The thread trimming device includes a moving knife that rotates, and a fixed knife that cuts a thread by being sandwiched between the moving knife, and the lower thread holding portion is moved toward the fixed knife by the moving knife. It has a structure that catches the lower thread.
That is, after the end of sewing, when the lower thread is cut by the thread trimming device, the lower thread holding portion of the thread guide plate captures the lower thread cutting end, It is possible to eliminate the setting of the lower thread.
JP-A-8-10484

  However, the lower thread holding part of the thread guide plate of the hook mechanism is formed at a position away from the lower thread feeding position by the bobbin case, and the lower thread is carried to the lower thread holding part by the moving knife of the thread trimming device. There was a problem that the bobbin thread was unwound from the bobbin until it was removed. For this reason, at the time of the next sewing, there was a problem that the thread tension was reduced and the knot was not formed well.

  It is an object of the present invention to ensure that the next sewing after cutting the lower thread is performed satisfactorily.

  The invention described in claim 1 includes a bobbin case for storing a bobbin for a bobbin thread, an inner hook that reciprocally rotates around the bobbin case, a cauldron that holds the inner hook in a reciprocating manner, and an upper portion of the cauldron The sewing machine hook mechanism is arranged below the thread trimming device in the sewing machine bed, and captures the lower thread to be paid by the moving knife of the thread trimming device. The lower thread holding part is provided, and the lower thread holding part is arranged closer to the lower thread lead-out part of the bobbin case than the lower thread passing position at the time of sewing with respect to the thread guide plate.

  It should be noted that the “bobbin case lower thread lead-out portion” refers to a portion where the lower thread restraint is separated from the guide means when the guide means for determining the yarn path of the lower thread from which the bobbin case is led out is provided.

  The invention described in claim 2 has a configuration similar to that of the invention described in claim 1, and adopts a configuration in which the lower thread holding portion is disposed above the lower thread leading portion of the bobbin case.

According to the first aspect of the present invention, in a state where the lower thread is drawn out from the bobbin case, the inner hook catches the upper thread from the sewing needle by the sword tip and extends the loop downward. The inner hook rotates in the opposite direction, and the upper thread is pulled by a balance provided on the sewing machine, thereby causing the inner hook and the bobbin case to pass through the loop. As a result, the lower thread is inserted into the upper thread loop to form a knot, and sewing is performed.
At the time of such sewing, the bobbin thread extends almost straight from the bobbin case bobbin thread lead-out portion toward the needle hole formed in the needle plate of the sewing machine, and is substantially constant with respect to the thread guide plate in the middle. Passing through the passing position.
When the lower thread is cut by the thread trimming device, the lower thread is moved and held from the lower thread passage position to the lower thread holding unit by the thread trimming device. At this time, since the lower thread is moved to the lower thread holding section closer to the lower thread lead-out section than the lower thread passage position, the lower thread feeding due to the movement is reduced.
Therefore, the lower thread end after cutting does not have an excessive length, and the occurrence of fluctuations in the thread tension can be suppressed during the next sewing, and a knot can be formed satisfactorily. This makes it possible to improve the sewing quality at the start of sewing.

  In the invention according to claim 2, since the lower thread holding part is arranged above the lower thread leading part, the lower thread holding part can be arranged closer to the lower thread leading part, and the lower thread holding part At this time, it is possible to further reduce the feeding of the extra lower thread and further improve the sewing quality in the next sewing.

(Overall configuration of the embodiment of the invention)
A shuttle mechanism 50 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing a main part of the sewing machine 10 on which the shuttle mechanism 50 is mounted.
Hereinafter, the direction parallel to the upper surface of the needle plate 11 described later and parallel to the shuttle shaft of the sewing machine 10 (not shown) is the Y axis direction, and the direction parallel to the upper surface of the needle plate 11 and perpendicular to the Y axis direction is the X axis. The direction of the sewing machine will be described with the direction perpendicular to the top surface of the needle plate 11 as the Z-axis direction.

The sewing machine 10 includes a frame 20 having a substantially U-shape as a whole. The frame 20 is located at a lower portion of the frame 20 and a vertical body portion that is raised from one end of the bed portion 21 and is not shown. And an arm part 22 extending in the same direction as the bed part 21 from the upper end of the vertical body part.
In the arm portion 22, an upper shaft is provided along the Y-axis direction to apply a vertical driving force to the needle bar that holds the sewing needle 12. A shuttle shaft for applying a driving force to 50 is disposed along the Y-axis direction.
The upper shaft performs full rotation in a fixed direction by a sewing machine motor, and transmits a reciprocating rotational driving force to the shuttle shaft through a transmission mechanism. Thus, the shuttle shaft is repeatedly rotated in the forward direction and in the reverse direction within a range of approximately half rotation in synchronism with the vertical movement of the sewing needle or at an integral multiple frequency.

FIG. 2 is a side view of one end portion of the bed portion 21 of the frame 20 as viewed from the line of sight along the Y-axis direction. As shown in the figure, a needle plate 11 is provided at a position below the sewing needle of the bed portion 21, and a needle hole 13 through which the sewing needle 12 is inserted during sewing is formed in the needle plate 11. Yes.
Further, a thread trimming device is disposed on the lower surface side of the needle plate 11, and a hook mechanism 50 is disposed below the thread trimming device while being built in the bed portion 21.

  The thread trimming device sandwiches a moving knife 14 rotatably supported on the lower surface side of the needle plate 11 and an upper thread and a lower thread D carried by the moving knife 14 between the moving knife 14. A fixed knife to be cut, a motor for rotating the moving knife 14 in a reciprocating direction, and a driving force transmission mechanism for connecting the motor and the moving knife 14 are provided.

The moving knife 14 is reciprocally rotated along the flat plate surface of the needle plate 12, and the reciprocating rotation range is set so as to pass vertically below the needle hole 13.
At the time of cutting, a portion of the needle thread 13 that hangs down from the sewing needle 12, a portion that folds back below the needle plate of the upper thread and heads toward the workpiece, and the lower thread D are inserted. Of these, it is necessary to cut the portion of the upper thread toward the workpiece and the lower thread D by folding back below the needle plate of the upper thread while leaving the portion of the upper thread hanging from the sewing needle 12.
Therefore, the moving knife 14 selects and captures only the portion of the upper thread that hangs down from the sewing needle 12 by the protrusion 14a in the reciprocating forward path, and on the reverse side of the upper thread needle plate on the opposite side of the protrusion 14a. It has a structure in which the part and the lower thread D which are folded back and go to the sewing object are captured and conveyed to the fixed knife.
In FIG. 4 to be described later, the moving knife 14 is shown at a stop position between the forward path and the return path. In FIG. 4, the moving knife 14 reciprocally rotates in the range of the arrow S, rotates clockwise in the figure on the forward path, and rotates counterclockwise on the return path.

(Hook mechanism)
3 is a perspective view of the shuttle mechanism 50, and FIG. 4 is a plan view.
As shown in FIG. 1, the hook mechanism 50 includes a bobbin case 51 that houses a bobbin 56 around which a lower thread D is wound, a middle hook 52 that reciprocates around the bobbin case 51, and a hook shaft to a middle hook. A driver 53 that transmits a driving force for reciprocating rotation to 52, a cauldron 54 that holds the inner hook 52 in a reciprocating manner and holds the inner hook 52 inside, and an inner hook press 55 for holding the inner hook 52 inside the cauldron 54. And a thread guide plate 60 for guiding the portion of the upper thread that hangs down from the sewing needle 12 and the portion of the upper thread that folds under the needle plate and heads toward the workpiece to be separated from each other.

As shown in FIG. 1, the cauldron 54 has a shape in which a large-diameter cylindrical part 54a and a small-diameter cylindrical part 54b are concentrically integrated. Is to be inserted.
Further, the large-diameter cylindrical portion 54a houses the inner hook 52, and a sliding surface is formed inside the inner hook 52 so as to slidably contact the outer peripheral portion of the inner hook 52 and guide its rotation. That is, the inner hook 52 is rotatably supported by the cauldron 54 by the sliding surface.

  The cauldron 54 is mounted on the sewing machine bed portion 21 so that the center line thereof is along the Y-axis direction, and the upper portion of the large-diameter cylindrical portion 54a is somewhat curved in the mounted state. Is formed. The substantially flat portion is cut out so as to penetrate to the inside, and a thread guide plate 60 is fixedly mounted on the substantially flat portion. Then, a lowered sewing needle is inserted into a notch formed in the substantially flat portion and a guide hole 65 described later formed in the thread guide plate 60, and the upper thread and the lower thread D are entangled and sewing is performed. It is like that.

The inner hook 52 is formed in a substantially fan shape, and a support shaft 52a is provided at the center thereof, and the bobbin 56 and the bobbin case 51 can be rotatably supported via the support shaft 52a. ing.
Further, the inner hook 52 is formed with a sliding contact surface that slides on the outer periphery of the outer hook 54 and a sharp sword tip 52b for catching the upper thread at one end of the outer periphery. Thus, the inner hook 52 reciprocates around the inner bobbin case 51, and the upper thread is captured by the sword tip 52b.

The driver 53 is housed inside the cauldron 54 together with the inner hook 52, and is fixedly supported by hugging at the tip of the hook shaft. The driver 53 is formed in a substantially fan shape, and at the time of reciprocating rotation by the hook shaft, one end portion and the other end portion of the driver 53 in the circumferential direction are alternately in contact with the inner hook 52, respectively. At the same time, reciprocal rotation is performed.
As described above, the inner hook 52 is not directly connected to the hook shaft but is pushed by the driver 53 connected to the hook shaft so as to reciprocate and rotate. Therefore, the inner hook 52 and the driver 53 are switched at the timing when the rotation direction is switched. By passing the upper thread loop through the gap with the inner hook 52, the inner hook 52 can be passed through the upper thread loop. As a result, the lower thread D fed out from the bobbin case 51 arranged inside the inner hook 52 can be inserted into the upper thread loop.
The inner hook 52 and the driver 53 are held in a large-diameter cylindrical portion 54 b of the cauldron 54 by an inner hook press 55 fixedly mounted on the end surface of the cauldron 54.

  The bobbin 56 includes a cylindrical central shaft portion around which the lower thread D is wound, and disk-shaped flange portions provided at both ends thereof, and the lower thread D is wound between the flange portions. The And it is supported by the inner hook 52 in a state where the support shaft 52a of the inner hook 52 is inserted into the cylindrical central shaft portion.

The bobbin case 51 is a cylindrical body with one end closed and the other opened, and the bobbin 56 can be stored inside thereof. The bobbin case 51 is mounted in the inner hook 52 with the bobbin 56 retracted, and is supported by the support shaft 52 a via the bobbin 56.
Further, on the closed end face side of the bobbin case 51, a rotation preventing projection 51a extending toward the outside in the radial direction is provided. The rotation preventing projection 51 a is fitted into a recess 55 a provided in the inner hook retainer 55 to prevent the bobbin case 51 and the bobbin 56 from rotating together with the inner hook 52.
Further, the protrusion 51a is bent at the tip end toward the back side, and a thread guide hole 51b is formed in the bent portion in a penetrating state. The bobbin case 51 has a through hole 51c formed on a cylindrical outer peripheral surface, and the lower thread D of the inner bobbin 56 is fed out from the through hole 51c and further inserted into the thread guide hole 51b. It is guided to the yarn guide plate 60 side. That is, the thread guide hole 51b is a guide means for determining the thread path of the lower thread D through which the bobbin case 56 is led out, and the outlet side (the upper end surface of the protrusion 51a) of the thread guide hole 51b Part.

(Thread guide plate)
As shown in FIG. 4, the thread guide plate 60 includes a main body plate 61 that is a rectangular flat plate, and a spring plate 62 having elasticity of a predetermined shape that is attached to the upper surface of the main body plate 61. The left and right ends are mounted on the upper portion of the cauldron 54 by two set screws 64. The spring plate 62 is fixed to the main body plate 61 by a set screw 64.

A guide hole 65 penetrating the front and back is formed in the center of the main body plate 61. The upper thread is guided to a predetermined position during sewing according to the shape of the guide hole 65, and the lower thread D is cut. Sometimes guides to a predetermined position.
The sewing needle 12 moves up and down with respect to a predetermined position of the guide hole 65 of the main body plate 61 (see FIG. 4), enters the inside of the cauldron 54 when the sewing needle 12 is lowered, and the upper thread inserted through the sewing needle 12 is in the middle. A loop is formed by being captured by the sword tip 52b of the hook 52. At this time, the inner shuttle 52 advances rightward with the sword tip 52b facing rightward in FIG. On the other hand, the main body plate 61 is formed with an upper thread distributing section 66 having a pointed tip in the direction opposite to the traveling direction of the sword tip 52b at the time of capturing the thread (left side in FIG. 4). Yes. That is, the guide hole 65 forms a thread path that is bifurcated with the upper thread distributing portion 66 interposed therebetween.
The upper thread caught by the sword tip 52b of the inner hook 52 by the upper thread allocating part 66 has a part on the upstream side and a part on the downstream side of the sword 52b on both sides of the upper thread allocating part 66, respectively. The upper thread loop is separated and spread. This prevents both side portions of the upper thread from being squeezed between the sliding contact portions of the inner hook 52 and the large hook 54 and causes the upper hook loop to pass through the inner hook until the sword tip 52b moves downward. It is possible to enlarge sufficiently.

Further, the lower thread D is inserted into the guide hole 65 of the main body plate 61 from below to above during sewing. In addition to the bifurcated path for guiding the upper thread, a path 68 for guiding the lower thread D to the lower thread holding portion 67 is formed in the guide hole 65.
The lower thread holding portion 67 is a part for holding the lower thread end portion after cutting at a predetermined length for the next sewing, and is described above at the end of the path 68 for guiding the lower thread D described above. The spring plate 62 is formed.
That is, the spring plate 62 includes a protrusion 62 a extending in a claw shape, and is disposed so that the protrusion 62 a crosses before the end of the path 68. Furthermore, the protrusion 62a appears to have its tip end substantially blocking the path 68 in a plan view, but when viewed from an obliquely upward direction inclined toward the tip end of the protrusion 62a, a gap for allowing the lower thread D to pass through the path 68 is formed. The tip position is adjusted so that.
When the lower thread D is cut, the lower thread D is moved along the path 68 by the moving knife 14 immediately before the cutting. At this time, the path passes through a narrow gap formed by the protrusion 62a. The end of 68 will be reached. After the cutting, the lower thread end portion is prevented from reverse movement by the protrusion 62a, and is thus held at the end of the path 68. That is, the region surrounded by the end of the path 68 and the protrusion 62 a is the lower thread holding portion 67.

The main body plate 61 has two folds W formed in accordance with the curved shape of the upper surface portion of the cauldron 64, and the main body plate 61 has three flat surfaces formed by the two folds W.
On the other hand, if the flat surface of the protrusion 62a of the spring plate 62 is not parallel to the flat surface on which the lower thread holding portion 67 of the three flat surfaces of the main body plate 61 is located, the tip of the protrusion 62a Is separated from the main body plate 61, the gap becomes excessively large, and the function of holding the lower thread cannot be performed.
For this reason, the projection 62a is arranged so as to be in the plane of the flat plate surface on which the lower thread holding portion 67 is located so that a large gap is not generated at the tip of the projection 62a, and the lower thread holding portion 67 is located. The spring plate 62 is fixed by a set screw 63 provided in the flat plate surface.

Further, the direction of the path 68 for guiding the lower thread D to the lower thread holding part 67 in the guide hole 65 and the arrangement setting of the lower thread holding part 67 will be described in detail.
As shown in FIG. 4, the path 68 for guiding the lower thread D to the lower thread holding portion 67 connects the needle drop position of the sewing needle 12 and the thread guide hole 51b (lower thread outlet portion) of the protrusion 51a in plan view. It is formed along a straight line.
Further, the moving knife 14 reciprocally rotates in the range of the arrow S shown in FIG. 4, but when the moving knife 14 rotates in the cutting direction, a position where the moving knife 14 contacts the lower thread D (lower thread passing position P described later). The arrangement of the moving knife 14 and the direction of the path 68 are set so that the tangential direction with respect to the arc-shaped movement trajectory of the moving knife 14 in FIG. Thereby, the lower thread D is moved to the thread holding part 67 side along the path 68 by contacting the moving knife 14 rotating in the cutting direction.

FIG. 5 is a sectional view taken along line VV in FIG. As shown in FIG. 5, the lower thread D forms a path that connects the thread guide hole 51b of the protrusion 51a to the needle hole 13 of the needle plate 11 with a substantially straight line during sewing. Therefore, the lower thread D passes through the thread guide plate 60 at a constant lower thread passage position P during sewing.
The lower thread holding portion 67 described above is desirably provided at a position closer to the thread guide hole 51b that is the lower thread lead-out section than the lower thread passage position P in plan view.
For example, in a plan view, the lower thread holding part 67 is more desirably on a line segment connecting the lower thread passing position P to the thread guide part 51b. In the present embodiment, the lower thread holding part 67 is arranged as a thread. It is set vertically above the guide hole 51b.

(Description of sewing machine operation)
The operation of the sewing machine 10 having the above configuration will be described.
In sewing, the sewing needle 12 inserted with the upper thread moves up and down, and when lowered, the sword tip 52b of the inner hook 52 captures the upper thread and stretches the loop downward. At this time, in the yarn guide plate 60, the upper yarn distributing section 66 of the yarn guide hole 65 pushes the loop of the upper yarn. When the sword tip 52b reaches the lowest position and the inner hook 52 is switched in the reverse direction, the upper thread loop away from the sword tip 52b is pulled up by a balance mechanism (not shown). As a result, the inner hook 52 Pass through the inside of the loop. Accordingly, the lower thread D is also inserted through the upper thread loop, a knot is formed, and sewing is performed.
Further, when the sewing is completed, the moving knife 14 is driven to perform thread trimming. First, the moving knife 14 is rotated by one way from the state in which the moving knife 14 is positioned on the stationary knife side and passes directly under the needle hole 13. As a result, the upstream portion (portion close to the upper yarn supply source) of the upper yarn that has been inserted through the needle hole 13 and the downstream portion of the upper yarn and the lower yarn D are distributed.
Next, the moving knife 14 rotates in a direction returning toward the fixed knife. As a result, the downstream portion of the upper thread and the lower thread D are captured by the moving knife 14 and carried to the stationary knife side. As a result, the lower thread D moves from the lower thread passage position P to the lower thread holding portion 67 along the path 68 and is held.
Further, the lower thread D and the upper thread move to the fixed knife and are cut.
Since the cut end portion of the lower thread D is held by the lower thread holding portion 67, it is not necessary to set the lower thread when performing new sewing after cutting.

(Effect of embodiment)
In the above configuration, in the shuttle mechanism 50, the lower thread holding portion 67 is provided vertically above the thread guide hole 51b that is closer to the thread guide hole 51b than the lower thread passage position P of the thread guide plate 60. In the movement of the lower thread D to the lower thread holding portion 67, the lower thread feeding amount from the bobbin 56 can be reduced.
Further, since the lower thread holding portion 67 is set vertically above the yarn guide hole 51b, the lower thread route from the yarn guide hole 51b to the lower thread holding portion 67 to the lower thread cutting position is bent and detoured. It is possible to reduce the amount of lower thread feeding until cutting.
Therefore, the lower thread end after cutting does not have an excessive length, and the occurrence of fluctuations in the thread tension can be suppressed during the next sewing, and a knot can be formed satisfactorily. This makes it possible to improve the sewing quality at the start of sewing.

It is a perspective view which shows the principal part of the sewing machine in which the shuttle mechanism is mounted. It is the side view which looked at the one end part of the bed part of a flame | frame with the eyes | visual_axis along the Y-axis direction. It is a perspective view of the shuttle mechanism disclosed in FIG. It is a top view of the shuttle mechanism disclosed in FIG. It is sectional drawing along the VV line in FIG.

Explanation of symbols

10 Sewing machine 11 Needle plate 12 Sewing needle 13 Needle hole 14 Moving knife 20 Frame 21 Bed (sewing machine bed)
50 Hook mechanism 51 Bobbin case 51a Projection 51b Thread guide hole (lower thread lead-out part)
52 Middle hook 54 Large hook 56 Bobbin 60 Thread guide plate 67 Lower thread holding part D Lower thread P Lower thread passage position

Claims (2)

A bobbin case for storing the bobbin of the lower thread;
An inner hook that reciprocates around the bobbin case;
A cauldron that holds the inner pot in a reciprocating manner and holds it inside;
A yarn guide plate disposed at the top of the cauldron,
In the hook mechanism of the sewing machine arranged below the thread trimmer in the sewing machine bed,
The thread guide plate is provided with a lower thread holding portion that captures a lower thread that is removed by the moving knife of the thread trimming device,
A sewing machine hook mechanism characterized in that the lower thread holding portion is disposed closer to the lower thread lead-out portion of the bobbin case than a lower thread passage position at the time of sewing with respect to the thread guide plate.   The sewing machine shuttle mechanism according to claim 1, wherein the lower thread holding portion is disposed vertically above the lower thread leading portion of the bobbin case.

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