JP2011101718A - Thread cutting device of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thread cutting device of a sewing machine to enable a stable thread cutting operation. <P>SOLUTION: The thread cutting device includes: a moving knife 2 supported such that the moving knife turns back and forth; a stand-by knife 3 supported such that the moving knife contacts the stand-by knife in a sliding manner and such that the stand-by knife turns back and forth; a cam mechanism 40 comprising a cam member 41 as a cam driver configured to rotate by obtaining power from a lower shaft 1, and a cam follower 44 configured to give a back and forth turning movement to the moving knife; an actuator 51 configured to connect and disconnect a power transmission between the cam mechanism and the moving knife by advancing the moving knife from the most retreated position and retreating the moving knife to the most retreated position; an interlocking mechanism 60 configured to interlock the stand-by knife with the advancing moving knife until the stand-by knife reaches its most advanced position; a stand-by mechanism 70 configured to hold the stand-by knife to prevent the stand-by knife from retreating when the moving knife retreats; a releasing means 24 for releasing the stand-by knife from the stand-by mechanism when the moving knife has passed the cutting position; and a returning means 12 for returning the stand-by knife to its most retreated position. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a yarn cutting device that cuts a yarn by cooperation of a moving knife and a standby knife.

A conventional thread cutting device for a sewing machine includes a moving knife that performs reciprocating rotation in the front-rear direction, a standby knife that advances and stands by to a cutting position, and performs thread cutting in cooperation with a moving knife that moves backward, and a shuttle shaft A cam mechanism for applying a reciprocating rotational motion to the moving knife with a drive source, an air cylinder for applying a forward movement operation from the initial position to the standby knife, and a moving direction provided in contact with the standby knife And a projection for interlocking the moving knife.
At the time of thread cutting, the air cylinder rotates the standby knife in the forward direction from its initial position, whereby the protrusion provided on the moving knife is pressed by the standby knife and the moving knife is also moved forward.
As a result, the cam roller that operates integrally with the moving knife enters the groove of the groove cam, and the forward movement of the moving knife is taken over by the cam mechanism. The cam mechanism reciprocally rotates the moving knife by the rotation of the cam shaft, captures the yarn when the moving knife moves backward, and draws the yarn to the cutting position.
Meanwhile, the standby knife is held at the cutting position by the air cylinder, and when the moving knife reaches the cutting position, the thread sandwiched between the blade edges is cut.

JP 2008-068004 A

However, in the yarn cutting device of Patent Document 1, the air cylinder has a function of advancing the standby knife to the cutting position, and a function of advancing the moving knife through the standby knife to guide the cam roller to the groove cam. And also has a function of holding the standby knife in cutting maintenance.
Since the moving knife is provided with a projection for interlocking with the standby knife, when the moving knife is retracted, the air cylinder is operated at an appropriate timing in order to avoid malfunction caused by the collision of the protrusion with the standby knife. The standby knife must be moved backward.
However, the air cylinder also has a function of holding the standby knife at the cutting position. If the standby knife is retracted too early, a cutting failure will occur. This makes it difficult to perform a good yarn cutting operation.
Also, depending on the type of thread, friction may occur when the standby knife moves backward after cutting, delaying the timing of the air cylinder's backward movement, making it difficult to adjust the operation timing of the air cylinder, and good thread cutting operation. It was difficult.

  An object of the present invention is to satisfactorily perform a yarn cutting operation.

  The invention according to claim 1 is a moving knife supported so as to be capable of reciprocating and rotating back and forth, a standby knife which is slidably contacted with the moving knife and supported so as to be capable of reciprocating and rotating back and forth, and retraction of the moving knife In a horizontal hook shuttle shaft or a sewing machine thread cutting device provided around it, which cuts the yarn in cooperation with the standby knife at the cutting position, the cam that rotates by obtaining power from the lower shaft A cam mechanism having an original cam body, a cam follower that imparts a back-and-forth reciprocating rotation to the moving knife, and connection and disconnection of power transmission of the moving knife to and from the cam mechanism, An actuator for giving each of the movement of the moving knife from the last retracted position and the backward movement to the last retracted position; and an interlocking mechanism linked to the moving knife that moves forward until the standby knife reaches its most advanced position. , When the moving knife moves backward A standby mechanism for waiting so that the standby knife does not move backward, a release means for releasing the standby state by the standby mechanism after passing the cutting position of the moving knife, and a return means for returning the standby knife to the last retracted position. It is characterized by that.

  The invention according to claim 2 has the same configuration as that of the invention according to claim 1, and the standby mechanism has a claw that locks the standby knife so as not to retract when the moving knife reaches the most advanced position. It is a latch mechanism, and the release means is a projecting body that moves backward together with the moving knife and moves the pawl in the releasing direction after passing the cutting position of the moving knife.

  The invention described in claim 3 has the same configuration as that of the invention described in claim 2, and the protruding body of the releasing means is formed of a separate member separable from the moving knife.

  The invention according to claim 4 has the same configuration as that of the invention according to any one of claims 1 to 3, and the interlocking mechanism is reciprocally rotated integrally with the moving knife or the moving knife. A member that performs an operation presses the standby knife or a member that performs a reciprocating rotation operation integrally with the standby knife, thereby causing only the movement in the forward direction of the moving knife to be interlocked with the standby knife. .

  The invention according to claim 5 has the same configuration as that of the invention according to any one of claims 1 to 4, and the actuator includes an operation unit that performs a reciprocating movement operation. The actuator is controlled so that the operating portion of the actuator can move freely according to an external force while being connected to the moving knife and being reciprocated by the cam mechanism. To do.

According to the first aspect of the present invention, the connection and disconnection of the power of the moving knife and the cam mechanism is switched by the actuator providing the longitudinal movement to the moving knife instead of the standby knife, so that it is the case of the prior art. In addition, there is no operational restriction that the actuator must be given a backward movement after waiting for the completion of the yarn cutting, and the cam mechanism and the actuator can be prevented from interfering with each other by appropriately adjusting the timing of the backward movement start of the actuator. Occurrence can be reduced, and a satisfactory cutting operation without any trouble can be realized.
In addition, since the actuator performs the back-and-forth operation on the moving knife instead of the standby knife, the influence of the delay of the standby knife operation due to the thread type can be reduced, and for this reason, a good cutting operation can be realized. It becomes possible.

  According to the second aspect of the present invention, the standby mechanism is a latch mechanism, and the projecting body that moves backward integrally with the moving knife releases the pawl of the latch mechanism. Unlike the case of synchronizing at this timing, the release timing at the time of the backward movement of the moving knife can always be made constant, and further satisfactory cutting operation can be realized.

  In the invention according to claim 3, since the projecting body of the release means is constituted by a separate member separable from the moving knife, the position of the moving knife can be adjusted without changing the release timing of the standby knife by the projecting body. Is possible.

  In the invention according to claim 4, since the moving knife and the standby knife are interlocked in the forward direction by the pressing contact between the knife or the members, only the forward direction of the moving knife and the standby knife is interlocked, and the backward direction is mutually free. The structure of the interlocking mechanism can be realized with a simple structure.

  According to the fifth aspect of the present invention, while the reciprocating motion is applied to the moving knife by the cam mechanism, the actuator is controlled so that the operating portion of the actuator can freely move according to the external force. It is possible to perform the operation of the cam mechanism without being affected by the actuator while eliminating the need for switching the interlocking between the moving knife and the cam mechanism.

It is a perspective view which shows the structure of the yarn cutting device in this embodiment. It is a perspective view which shows a moving knife and a moving knife support mechanism. It is the top view which notched a part of front-end | tip part of a moving knife. It is a disassembled perspective view of a standby knife support means. It is a top view around a waiting knife. It is a perspective view of a cam mechanism and an air cylinder mechanism. It is sectional drawing of the cam mechanism and air cylinder mechanism which showed the cross section which passes along the centerline of the moving knife link shaft of a moving knife shaft and a cam mechanism. It is a perspective view of the thread cutting device shown excluding the shuttle shaft. It is the perspective view which looked at the hook shaft stand from the lower part. It is operation | movement explanatory drawing at the time of a thread | yarn cutting | disconnection, and operation | movement advances in order of FIG. It is operation | movement explanatory drawing at the time of the thread | yarn cutting following FIG. 10, and operation | movement advances in order of FIG. 11 (A)-(C). It is operation | movement explanatory drawing at the time of the thread | yarn cutting following FIG. 11, and operation | movement advances in order of FIG. 12 (A)-(C). It is a perspective view which shows the other example of a reset means. It is a top view which shows the example which added the adjustment structure of the waiting knife.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.
The embodiments described below are provided with various technically preferable limitations for carrying out the present invention, but the scope of the invention is not limited to the following embodiments and illustrated examples. In the present embodiment, the direction of each part of the thread cutting device 10 of the sewing machine will be described with reference to the XYZ axes shown in the drawings. The Z-axis direction indicates the vertical vertical direction, and both the X-axis direction and the Y-axis direction indicate horizontal directions that are orthogonal to each other. The yarn cutting device 10 installed in the sewing machine will be described on the assumption that the sewing machine is installed on a horizontal plane and the longitudinal direction of the sewing machine bed portion is oriented parallel to the Y-axis direction. Shall.

(sewing machine)
In the present embodiment, the sewing machine is not particularly limited, but here, a case where the sewing machine is mounted on a general feed sewing machine will be described as an example. An integrated feed sewing machine (hereinafter simply referred to as a sewing machine), for example, synchronizes the up and down movement of the sewing needle by the needle up / down movement mechanism and the needle movement by the needle movement mechanism in order to prevent the displacement of the sewing product accompanying the feed operation. This is a sewing machine that feeds with a sewing needle pierced into a thick sewing object (for example, a skin) by synchronizing the needle feeding operation with the feeding operation by the upper feeding mechanism and the lower feeding mechanism.
Although not shown, the sewing machine is provided with a well-known needle up-and-down movement mechanism in the sewing machine arm part, and a horizontal hook is provided below the needle plate in the sewing machine bed part. The needle vertical movement mechanism is transmitted with the power of the sewing machine motor via the upper shaft, and the horizontal shuttle is transmitted with the power of the sewing machine motor via the lower shaft and the shuttle shaft. The upper shaft and the lower shaft are disposed in parallel with the Y-axis direction, and the shuttle shaft is disposed in parallel with the Z-axis direction. Further, the lower shaft and the shuttle shaft are each provided with a bevel gear that meshes with each other to transmit power.
Since various configurations generally mounted on other sewing machines are well known, the description thereof will be omitted here.

(Thread cutting device)
Next, the configuration of the yarn cutting device 10 in the present embodiment will be described in detail.
FIG. 1 is a perspective view showing the overall configuration of the yarn cutting device 10.
The thread cutting device 10 includes a hook shaft 11 that supports the hook shaft in the sewing machine bed, a moving knife 2 that reciprocally rotates back and forth, and a moving knife that can be reciprocated with respect to the hook shaft 11. The moving knife support mechanism 20 that supports the moving knife 2, the waiting knife 3 that slides back and forth while sliding in contact with the moving knife 2, and the waiting knife 3 that supports reciprocating rotation with respect to the hook shaft base 11 are supported. A standby knife supporting means 30 for performing the above operation, a cam mechanism 40 as a first operation applying mechanism for applying a reciprocating rotation operation to the moving knife 2, and a second operation applying mechanism for applying a reciprocating rotation operation to the moving knife 2. An air cylinder mechanism 50, an interlocking mechanism 60 that interlocks the standby knife 3 with respect to a forward movement (in the direction of the black arrow in FIG. 1) from a predetermined position before the most advanced position of the moving knife 2 to the most advanced position, and a moving knife. 2 backward movement (the white arrow in Fig. 1) ), A standby mechanism 70 that makes the standby knife 3 stand by so as not to retreat, a protrusion (projection) 24 as a release means that releases the standby state by the standby mechanism 70 after passing the cutting position of the moving knife 2, and a standby A return spring 12 is provided as return means for returning the knife 3 to the last retracted position.

(Cook shaft base)
The shuttle shaft base 11 is fixedly installed below a feed dog (not shown) in the sewing machine bed portion, and supports almost all components of the yarn cutting device 10. Further, the hook shaft base 11 has a through hole along the Y axis direction through which the lower shaft 1 is inserted, and a through hole along the Z axis direction through which the hook shaft is inserted adjacent to the through hole. Is formed. Power is transmitted from the lower shaft to the hook shaft via the cap gear, and a rotational force is applied to the horizontal hook provided at the upper end of the hook shaft (just above the hook shaft base 11). ing. A moving knife 2 to be described later is arranged to reciprocate and rotate just above the horizontal hook.

(Moving knife and moving knife support mechanism)
FIG. 2 is a perspective view showing the moving knife 2 and the moving knife support mechanism 20.
The moving knife support mechanism 20 includes a moving knife shaft 21 serving as a central axis of the rotating operation of the moving knife 2, a support plate 22 formed integrally with the upper end of the moving knife shaft 21, and an upper surface of the support plate 22. The moving knife base 23 is mounted by screwing, and the moving knife base 23 also holds the proximal end portion of the moving knife 2 by screwing.
The moving knife shaft 21 is rotatably supported with respect to the shuttle shaft base 11 via a hollow standby knife shaft 31 described later in a state parallel to the Z-axis direction. As a result, the moving knife 2 reciprocates around the Z axis, and the rotating end of the moving knife 2 reciprocates along the XY plane.

The support plate 22 has a flat plate shape along the XY plane, and includes a projecting portion 24 and an input portion 25 that extend outward in the radial direction around the moving knife shaft 21. .
The projecting portion 24 has its tip end linked to the backward rotation of the moving knife 2 (in the direction of the white arrow in FIG. 1) at a predetermined timing in a standby state (backward prevention state) of the standby knife 3 by a standby mechanism 70 described later. ), And its action will be described in detail in the description of the structure of the standby mechanism 70.
The input unit 25 is provided on its upper surface with a square piece 46 of a cam mechanism 40, which will be described later, so that it can be rotated around the Z axis by a step screw. 22 is performed.
Furthermore, an interlocking pin 61 of an interlocking mechanism 60 described later is provided on the lower surface of the support plate 22 so as to protrude downward adjacent to the moving knife shaft 21.
A positioning pin 26 of the moving knife base 23 is provided on the upper surface of the support plate 22 so as to protrude upward. The positioning pin 26 is provided so as to be concentric with the moving knife shaft 21 described above.

The moving knife base 23 is formed with a holding groove 27 for holding the base end of the moving knife 2, and the base end of the moving knife 2 is moved along the holding groove 27 and fixed with a set screw 28. This makes it possible to adjust the position in the same direction. The holding groove 27 is provided on the axis of the moving knife shaft 21 described above, and enables adjustment of the turning radius of the tip of the moving knife 2.
Further, the moving knife base 23 has a fitting hole (not shown) that fits the positioning pin 26 described above on the lower surface side thereof. The moving knife base 23 is attached to the support plate 22 through a through hole that is somewhat larger than the outer diameter of the set screw 29, and is rotated around the positioning pin 26 and fastened with the set screw 29. The angle of the moving knife 2 around the moving knife shaft 21 can be adjusted. By such angle adjustment, it is possible to adjust the most advanced position and cutting position of the moving knife 2.

The moving knife 2 has a base end 2a that extends straightly held by the moving knife base 23, and a cutting edge 2c that cuts a thread is formed at the distal end 2b that is greatly curved and extended from the base end 2a. ing. The moving knife 2 is rotatably supported by the moving knife support mechanism 20 described above, and moves forward (in the direction of the black arrow in FIG. 1) so that the tip of the moving knife 2 approaches the needle drop position. It moves in a direction away from the needle drop position by performing backward rotation (in the direction of the white arrow in FIG. 1).
Further, a locking portion for catching the thread is formed on the lower surface side of the distal end portion 2b of the moving knife 2, and the most advanced position in the rotation is the position where the locking portion of the moving knife 2 has the needle drop position. It is set to the position that passed the minute.
FIG. 3 is a plan view in which a part of the tip 2b of the moving knife 2 is cut away. The tip 2b of the moving knife 2 is formed in a sharp shape, and its longitudinal direction extends along an arc centered on the moving knife shaft 21. A through hole 2d is formed in the vicinity of the tip from the outer side surface to the inner side surface. The through hole 2d is formed so as to be inclined with respect to the outer side surface, and a portion of the end edge portion of the through hole 2d from the tip is a blade edge 2c. The cutting edge 2c has an acute angle by forming the through hole 2d obliquely, and the thread is cut by being sandwiched between the cutting edge 2c and the cutting edge 3a at the tip of the standby knife 3. Yes.

(Standing knife and waiting knife support means)
4 is an exploded perspective view of the standby knife supporting means, and FIG. 5 is a plan view of the vicinity of the standby knife.
The standby knife support mechanism 30 includes a standby knife shaft 31 serving as a central axis of the rotation operation of the standby knife 3, an arm-shaped standby knife base 32 fixedly mounted on the upper end portion of the standby knife shaft 31, and the shuttle shaft base 11. And a metal bearing 33 which is mounted in an opening formed along the Z-axis direction and supports the standby female shaft 31 rotatably.
As described above, the standby knife shaft 31 is formed in a hollow shape, and has a structure in which the moving knife shaft 21 is inserted and rotatably supported.
The base of the standby knife 32 is attached to the upper end of the standby knife shaft 31 by hugging, and the standby knife 3 is attached to the rotating end thereof.

Further, the standby knife base 32 is connected to a return spring 12 that constantly urges rotation in the backward rotation direction (the direction in which the standby knife 3 is separated from the needle drop position: the direction of the white arrow in FIG. 1). As long as an external force in the forward rotation direction is not applied, the apparatus stands by at the last retracted position (position shown in FIG. 5) in contact with the stopper 34.
The metal bearing 33 is provided with a height adjusting screw 37 for adjusting the height of the standby knife shaft 31 and the moving knife shaft 21 up and down via the bearing 33 (see FIGS. 1 and 7). The height adjusting screw 37 is rotatably supported through the shuttle shaft base 11 along the X-axis direction, and an eccentric protrusion is provided at the tip thereof. It is inserted into the provided recess. When the height adjusting screw 37 is rotated, the eccentric protrusion at the tip thereof changes in the vertical direction. Accordingly, the metal bearing 33 is also adjusted in the vertical direction, and the moving knife 2 and the standby knife 3 are also adjusted. Similarly, the height is adjusted.

The standby knife 3 has a flat plate shape along the outer side surface of the moving knife 2, and the tip thereof is a cutting edge 3 a. The cutting edge 3a of the standby knife 3 is arranged so as to be in sliding contact with the relative rotation of the moving knife 2 and the standby knife 3, and as described above, at the cutting position where the mutual cutting edge 2a and the cutting edge 3a face each other. The thread is cut.
The standby knife 3 is moved to the most advanced position (cutting position) close to the needle drop position by the forward rotation of the standby knife table 32, whereby the length of the remaining end portion of the thread from the sewing product after cutting is obtained. Can be made as short as possible.
In addition, a thread guide 35 is provided outside the standby knife 3, and the tip of the thread guide 35 is sandwiched between the blade tip 3a of the standby knife 3 and the blade tip 2c of the moving knife 2 and is not cut. So that the thread is guided.
In addition, as shown in FIG. 1, a clamp spring 36 is attached to the shuttle shaft base 11 via a clamp spring base 38. The clamp spring 36 is provided so as to be in pressure contact with the inner side surface of the moving knife 2, and holds the cut end portion of the thread extending from the horizontal hook side between the inner side surface of the moving knife 2 and the clamp spring 36. It has become.

(Cam mechanism)
6 is a perspective view of the cam mechanism 40 and the air cylinder mechanism 50, and FIG. FIG. 8 is a perspective view of the yarn cutting device 10 illustrated with the hook shaft 11 removed, and FIG. 9 is a perspective view of the hook shaft 11 as viewed from below.
The cam mechanism 40 is fixedly mounted on the lower shaft 1, and is supported by the cam body 41 serving as an original node having a cam groove 41 a formed on the outer peripheral surface thereof, and the shuttle shaft base 11 so as to be rotatable along the Z-axis direction. The moving knife link shaft 42, the moving knife driving arm 43 fixedly mounted on the lower end of the moving knife link shaft 42, and the cam provided upward at the rotating end of the moving knife driving arm 43. A cam roller 44 as a follower, a moving knife link arm 45 fixedly mounted on the upper end of the moving knife link shaft 42, and a movable knife link arm 45 engaged with the support plate 22 and the moving knife 2 to rotate. And a square piece 46 for transmission.

The cam body 41 has a cylindrical shape centered on the lower shaft 1, and a cam groove 41 a is formed on the outer peripheral surface thereof. The cam groove 41 a is formed with an entrance and an exit on one end face side of the cam body 41, and the cam roller 44 enters from the entrance of the cam groove 41 a by the rotation of the moving knife driving arm 43. .
The cam roller 44 is a cylindrical body formed along the Z-axis direction, and stands by at a position away from one end face of the cam body 41 when the yarn is not cut, and a moving knife driving arm is driven by an air cylinder mechanism 50 described later. 43 is rotated to the cam body 41 side and enters from the entrance of the cam groove 41a. Then, the cam roller 44 after entering gives a reciprocating rotation to the moving knife driving arm 43 according to the displacement of the cam groove 41a, and is discharged from the cam groove 41a. After discharging, the moving knife driving arm 43 is rotated in a direction away from the cam body 41 by the air cylinder mechanism 50 in the same manner as when entering, and the cam roller 44 is returned to the original standby position.

  The moving knife drive arm 43 extends outward in the radial direction with the moving knife link shaft 42 as the center, and holds a cam roller 44 at its extended end. The reciprocating rotation is given according to the displacement of the cam groove 41a through the cam roller 44, and the thread cutting operation by the reciprocating rotation is given to the moving knife 2 through the moving knife link shaft 42, the moving knife link arm 45 and the like. have. When the cam groove 41a is rotated, the moving knife driving arm 43 reciprocates in the clockwise direction (the direction of the black arrow) and the counterclockwise direction (the direction of the white arrow) in FIG. .

The moving knife link arm 45 is directly connected to the moving knife driving arm 43 by the moving knife link shaft 42 and rotates in conjunction with the moving knife link arm 45.
The moving knife link arm 45 is formed with a notch 45a having a long groove shape along the radial direction from the rotating end portion toward the moving knife link shaft 42 side. A square piece 46 is fitted inside the cutout 45a, and can be slid along the longitudinal direction of the cutout 45a. Accordingly, when the moving knife link arm 45 is rotated by the cam body 41, the square piece 46 moves along a locus of an arc centered on the moving knife shaft 21, so that the square piece 46 and the moving knife link shaft 42 are moved. However, the distance change is absorbed by the square piece 46 sliding along the notch 45a. Therefore, when the moving knife link arm 45 reciprocates, the support plate 22 also reciprocates around the moving knife axis, and the reciprocating operation is smoothly transmitted to the moving knife 2.
Since the moving knife link arm 45 and the support plate 22 rotate in opposite directions, the support plate 22 reciprocates in the order of counterclockwise and clockwise in FIG. That is, the moving knife 2 moves forward (in the direction of the black arrow in FIG. 6) by the cam groove 41a of the cam body 41 and then moves backward (in the direction of the white arrow in FIG. 6).

(Air cylinder mechanism)
The air cylinder mechanism 50 will be described with reference to FIGS. 1 and 6 to 9. The air cylinder mechanism 50 includes an air cylinder 51 as an actuator that is mounted with a bracket 52 fixed to the lower portion of the shuttle shaft base 11 so that the operation direction is directed in the Y-axis direction, and a plunger that moves the air cylinder 51 forward and backward. A joint 53 as an operating part attached to the tip, an input arm 54 whose base end is fixed to the lower end of the moving knife shaft 21 by being clamped, and a rotating end of the input arm 54 and the joint 53 are connected. The pin 55 is provided.

The input arm 54 is pivotally supported by the moving knife shaft 21, and its rotating end is connected to the joint 53 of the plunger of the air cylinder 51. That is, it has a structure in which a rotating operation is applied to the moving knife shaft 21 in accordance with the output of the advancing / retreating operation of the air cylinder 51.
While the joint 53 of the air cylinder 51 performs a rectilinear operation, the rotating end of the input arm 54 moves along an arc locus. However, since the air cylinder 51 is connected to the bracket 52 by a pin, the input arm 54 The displacement in the X-axis direction due to the arc movement of the arc 54 is absorbed, and the input arm 54 rotates smoothly by driving the air cylinder 51.

The main function of the air cylinder mechanism 50 is to move the moving knife 2 in the last retracted position forward so that the cam roller 44 of the cam mechanism 40 interlocked with the moving knife 2 enters the cam groove 41a of the cam body 41. The driving source of the pivoting operation is switched to the cam mechanism 40, and the reciprocating pivoting of the moving knife 2 by the cam mechanism 40 is completed, and the moving knife 2 is retracted to the last retracted position after the cam roller 44 is discharged from the cam groove 41a. In addition, the moving knife 2 is held at the last retracted position.
As the air cylinder 51, a so-called reciprocating type having individual air chambers for imparting forward movement and backward movement to the plunger is used. That is, during forward movement, compressed air is supplied to the forward-side air chamber and the backward-side air chamber is opened to the atmosphere. During backward movement, compressed air is supplied to the backward-side air chamber and forward-side air chamber. Are open to the atmosphere. That is, although not shown, the yarn cutting device 10 includes an air circuit capable of performing the above-described control with respect to the air cylinder 51, and an electromagnetic for performing the supply of the compressed air and the release of the atmosphere. The valve is controlled by a control circuit of the sewing machine.
Further, since the plunger 53 remains connected to the input arm 54 even after the driving source of the reciprocating motion of the moving knife 2 is transferred to the cam mechanism 40, the air cylinder 51 is moved by the cam mechanism 40. When the pivoting operation is applied to the shaft 21, the plunger of the air cylinder 51 also performs the front-rear operation through the input arm 54. Therefore, during the period when the reciprocating motion of the moving knife 2 is driven by the cam mechanism 40, both air chambers of the air cylinder 51 are opened to the atmosphere, and control is performed so that the plunger is in a free state. Thereby, the reciprocating rotation operation of the moving knife 2 by the cam mechanism 40 is smoothly performed without being influenced by the air cylinder 51. Then, when the reciprocating rotation by the cam mechanism 40 is completed and the cam roller 44 is discharged from the cam groove 41a, the compressed air is supplied to the backward air chamber and the forward air chamber is kept open to the atmosphere. The moving knife 2 is returned to the last retracted position.
The timing at which both air chambers of the air cylinder 51 are opened to the atmosphere and the timing at which the supply of compressed air is restored again is the timing at which the cam roller 44 enters the cam groove 41a and the timing at which it is discharged. It can be obtained by monitoring the angle or the lower axis angle. Therefore, the air cylinder 51 is controlled at an appropriate timing using an upper shaft angle detection device or the like normally mounted on the sewing machine.

(Interlocking mechanism)
As shown in FIGS. 1, 4, 5, and 8, the interlocking mechanism 60 includes an interlocking pin 61 fixedly provided on the lower surface of the support plate 22 and a fan-shaped standby knife fixing plate disposed at the upper end of the standby knife shaft 31. 62 and a set screw 63 for fixing the standby knife fixing plate 62 to the standby knife base 32.
That is, the standby knife fixing plate 62 includes a through hole into which the standby knife shaft 31 is inserted, and is rotatable about the standby knife shaft 31. Further, the standby knife fixing plate 62 is formed with a long hole 62a extending along an arc centering on the standby knife shaft 31, and the set screw 63 is attached to the standby knife base 32 in a state of being inserted into the elongated hole 62a. When fastened to the provided screw hole, the standby knife fixing plate 62 is fixed with respect to the standby knife shaft 31 so as to rotate integrally. Also, by loosening the set screw 63, The angle of the standby knife fixing plate 62 with respect to the standby knife shaft 31 can be adjusted within the range of the elongated hole 62a, and the cutting position can be adjusted by such angle adjustment.

The interlocking pin 61 is located away from the standby knife fixing plate 62 when the moving knife 2 is in the last retracted position, and when the moving knife 2 starts to rotate forward and reaches a predetermined angle, After that, the interlocking pin 61 presses the standby knife fixing plate 62 and maintains the relative position between the moving knife 2 and the standby knife 3 until the moving knife 2 reaches the most advanced position. These are simultaneously rotated. Since the interlocking pin 61 presses the standby knife fixing plate 62 to interlock, the interlocking state is released when the moving knife 2 starts to retract from the most advanced position.
At the time of thread cutting, there is a certain angle difference between the most advanced position of the moving knife 2 and the most advanced position of the standby knife 3 (in the case of the standby knife 3, the most advanced position is also the cutting position). 60, the positional relationship between the interlocking pin 61 and the standby knife fixing plate 62 is set so that the moving knife 2 and the standby knife 3 rotate in conjunction with the forward direction while maintaining the angular difference.

(Standby mechanism)
As shown in FIGS. 1, 5, and 8, the standby mechanism 70 includes a standby knife stopper 71 provided on the shuttle shaft base 11 adjacent to the standby knife fixing plate 62, and the standby knife stopper 71 locks the standby knife fixing plate 62. And a stopper spring 72 for urging in the direction.
The standby knife stopper 71 is pivotally supported by a step screw 73 along the Z-axis direction so as to be rotatable with respect to the shuttle shaft base 11, and a locking claw 74 is provided at the rotating end. It is equipped to protrude toward the waiting knife fixing plate 62.
When the standby knife 3 is located at the last retracted position, the tip of the locking claw 74 of the standby knife stopper 71 is pressed by the bias of the stopper spring 72 against the arcuate edge of the projection 24 provided on the support plate 22. The protruding portion 24 and the standby knife stopper 71 are arranged so as to contact each other (see FIG. 10A). When the standby knife 3 is rotated forward to the most advanced position, the standby knife fixing plate is arranged such that the end of the arc-shaped end edge of the standby knife fixing plate 62 passes through the locking claw 74 of the standby knife stopper 71. The attachment angle of 62 to the standby knife shaft 31 is adjusted. As a result, the locking claw 74 of the standby knife stopper 71 is locked to the terminal corner of the arc-shaped end edge of the standby knife fixing plate 62 by the biasing of the stopper spring 72, and the standby knife 3 moves backward from the most advanced position. It is held so as not to rotate (see FIG. 11B). That is, the standby mechanism 70 functions as a latch mechanism including the standby knife fixing plate 62. The standby knife 3 is always urged in the backward rotation direction by the return spring 12 via the standby knife base 32, but the moving knife 2 rotates in the backward rotation direction by holding by the standby mechanism 70 and interlocks. Even if the interlocking state by the mechanism 60 is released, the standby knife 3 maintains the most advanced position.

  The holding state of the standby mechanism 70 is released by the projection 24 provided on the support plate 22 described above. When the moving knife 2 rotates in the backward direction, the yarn is at a position (cutting position in the moving knife 2) where the cutting edge 3a of the standby knife 3 held by the holding mechanism 70 and the cutting edge 2c of the moving knife 2 retracted match. And after the moving knife 2 passes through at least this cutting position, the projection 24 comes into contact with the locking claw 74 of the standby knife stopper 71 and pushes back the locking claw 74 against the stopper spring 72. It has become. Thus, the holding state of the standby knife fixing plate 62 by the locking claw 74 is released, and the standby knife 3 is urged by the return spring 12 and returned to the last retracted position.

(Thread cutting operation by thread cutting device)
The yarn cutting operation of the yarn cutting device 10 having the above configuration will be described with reference to the operation explanatory diagrams of FIGS.
During sewing of the sewing machine, the moving knife 2 and the standby knife 3 are waiting at their last retracted positions. When a thread trimming signal is input after sewing the sewing machine, the air cylinder 51 is actuated to start the forward rotation of the moving knife 2 (FIG. 10A). At this stage, the interlocking pin 61 of the interlocking mechanism 60 has not yet reached the standby knife fixing plate 62, and the standby knife 3 is still in the standby state.
As the moving knife 2 rotates, the cam roller 44 of the cam mechanism 40 enters the cam groove 41a of the cam body 41, and the air cylinder 51 is controlled to be switched to the plunger free state. Then, when the moving knife 2 is switched to the operation by the cam mechanism 40 and then the moving knife 2 and the standby knife 3 reach a predetermined opening angle (angle difference between the most advanced positions), the interlocking pin 61 is moved to the standby knife fixing plate. When the contact knife 62 abuts on 62 (FIG. 10B) and is pressed, the standby knife 3 starts to rotate forward in conjunction with the moving knife 2 (FIG. 10C).

Then, the locking claw 74 of the standby knife stopper 71 of the standby mechanism 70 locks the end of the standby knife fixing plate 62 (FIG. 11A), and the moving knife 2 and the standby knife 3 are at their most advanced positions. It reaches (FIG. 11B). At this time, the tip of the moving knife 2 has entered the loop of the thread captured by the blade tip of the horizontal hook at the final needle.
And the cam mechanism 40 switches to provision of backward rotation, and the moving knife 2 starts backward rotation independently. As a result, the moving knife 2 captures the yarn and draws it toward the standby knife 3 that stands by at the cutting position (most advanced position).
When the moving knife 2 comes into contact with the cutting position, the thread is cut in cooperation with the standby knife 3 (FIG. 11C).

Further, when the moving knife 2 continues to retreat, the projecting portion 24 comes into contact with the locking claw 74 of the standby knife stopper 71 and pushes it back outward (FIG. 12A).
As a result, the standby knife fixing plate 62 is released, and the standby knife 3 is pulled back to the last retracted position by the return spring 12 (FIG. 12B).
Then, the cam roller 44 of the cam mechanism 40 is discharged from the cam groove 41a, and the air cylinder 51 is released from the free state of the plunger and driven backward. Thereby, the moving knife 2 is pulled back to the last retracted position, and the yarn cutting operation is completed (FIG. 12C).

(Effect of thread cutting device)
Since the thread cutting device 10 switches the connection and cutting of power between the moving knife 2 and the cam mechanism 40 when the air cylinder 51 imparts the longitudinal movement to the moving knife 2 instead of the standby knife 3. There is no need to retract the standby knife by the air cylinder at a very accurate timing with respect to the moving knife moving backward by the cam mechanism as in the case of the technology, and the timing for starting the backward movement of the air cylinder 51 is appropriately set. By adjusting, the occurrence of interference between the cam mechanism 40 and the air cylinder 51 can be reduced, and a satisfactory cutting operation without any trouble can be realized.
In addition, since the air cylinder 51 gives the longitudinal movement to the moving knife 2 instead of the standby knife 3, the influence of the operation delay of the waiting knife 3 due to the thread type is reduced, and the cutting operation is also good for this reason. Can be realized.

Further, the standby mechanism 70 is a latch mechanism that restricts the rotation of the standby knife 3 using the locking claw 74, and the protrusion 24 that moves backward together with the moving knife 2 releases the locking claw 74. Unlike the case where the knife 2 and the standby knife 3 are operated by separate drive sources and synchronized at a predetermined timing, the release timing at the time of the backward movement of the moving knife 2 can be made constant, and further excellent cutting operation Can be realized.
Furthermore, since the support plate 22 including the protrusion 24 is formed of a separate member that can be separated from the moving knife 2, the position of the moving knife 2 can be adjusted without changing the release timing of the standby knife 3 by the protrusion 24. It becomes possible.
Further, since the interlocking pin 61 operating integrally with the moving knife 2 and the standby knife fixing plate 62 operating integrally with the standby knife 3 are pressed against each other, the moving knife 2 and the standby knife 3 are linked in the forward direction. The structure of the interlocking mechanism that interlocks only the moving direction of the moving knife 2 and the standby knife 3 and makes the retracting directions free can be realized with a simple structure.
Further, while the reciprocating motion is applied to the moving knife 2 by the cam mechanism 40, the air cylinder 51 is controlled so that the joint 53 of the air cylinder 51 can freely move according to the external force. The cam mechanism 40 can be imparted without being affected by the air cylinder 51, without requiring a means for switching the interlocking between the air cylinder 51 or the moving knife 2 and the cam mechanism 40.

(Other)
In the yarn cutting device 10 described above, the return spring 12 is used as the return means. However, the present invention is not limited to this, and an actuator may be used.
For example, as in the example shown in FIG. 13, the air cylinder 12A may be used as an actuator as a return means. In this case, a joint attached to the plunger of the air cylinder 12A is connected to the rotation end of the input arm 13A that is connected to the standby knife shaft 31 (not shown in FIG. 13) and rotates together with the standby knife shaft 31, When the standby state of the standby mechanism 70 (not shown in FIG. 13) is released, the air cylinder 12A is operated to control the standby knife 3 to return from the most advanced position to the last retracted position. The moving knife 2 is driven by an air cylinder 12A connected to a rotating end of an input arm 13A that is connected to the moving knife link shaft 42 and rotates together with the moving knife link shaft 42.
Also in this configuration, it is desirable to control the pneumatic circuit so that the plunger is free while the standby knife 3 is rotating forward by the interlocking mechanism 60 (not shown in FIG. 13).

  Further, in the yarn cutting device 10, control is performed to make the plunger of the air cylinder 51 free during a period in which power is applied to the moving knife 2 by the cam mechanism 40. The air cylinder 51 may perform control to maintain the position of the plunger in the retracted position and the advanced position without releasing the atmosphere. In that case, the joint 53 and the input arm 54 are connected by an elastic member such as a spring so that the air cylinder 51 does not hinder the operation during the period in which the moving mechanism 2 is rotated by the cam mechanism 40. It is desirable to do. As a result, during the power application period of the cam mechanism 40, the input arm 54 can move away from the joint 53 while extending the spring. Alternatively, the joint 53 and the input arm 54 may be connected by a magnet or the like so that they can be separated from each other during the power application period of the cam mechanism 40. In any case, when the power application period of the cam mechanism 40 ends, the operating knife 2 can be returned to the last retracted position by driving the joint 53 of the air cylinder 51 to move backward again.

  In the above embodiment, the standby knife 3 is fixedly mounted on the rotating end of the standby knife base 32. However, as shown in the example shown in FIG. A long hole 3b generally extending in the moving radius direction may be formed and fastened to the rotating end of the standby knife base 32 with two set screws 3c through the long hole 3b. With such a structure, the standby knife 3 can be moved and adjusted along the rotational radius direction, and the engagement of the standby knife 3 and the moving knife 2 can be adjusted.

1 Lower shaft 2 Moving knife 3 Standby knife 10 Thread cutting device 12 Return spring (return means)
24 Projection (Release means, projecting body)
40 Cam mechanism 41 Cam body (original section)
44 Cam Roller (Cam Follower)
51 Air cylinder (actuator)
53 Joint (operation part)
60 Interlocking mechanism 61 Interlocking pin 62 Standby knife fixing plate 70 Standby mechanism 74 Locking claw

Claims (5)

A moving knife supported so as to be able to reciprocate back and forth,
A standby knife that is slidably contacted with the moving knife and supported so as to be capable of reciprocating back and forth;
In a thread cutting device for a horizontal hook, or a sewing machine provided in the periphery thereof, which performs thread cutting in cooperation with the standby knife at the cutting position when the moving knife moves backward,
A cam mechanism having a cam body serving as an original node of a cam that rotates by obtaining power from a lower shaft, and a cam follower that imparts a back-and-forth reciprocating rotation to the moving knife;
An actuator for providing connection and disconnection of power transmission of the moving knife to and from the cam mechanism, and each movement of the moving knife forward and backward to the last retracted position;
An interlocking mechanism that interlocks with the moving knife that moves forward until the standby knife reaches its most advanced position;
A standby mechanism for waiting so that the standby knife does not move backward when the moving knife moves backward;
Release means for releasing the standby state by the standby mechanism after passing through the cutting position of the moving knife;
A thread cutting device for a sewing machine, comprising: return means for returning the standby knife to the last retracted position. The standby mechanism is a latch mechanism having a claw that locks the standby knife so as not to retract when the moving knife reaches the most advanced position.
2. The sewing machine according to claim 1, wherein the releasing means is a protruding body that moves backward integrally with the moving knife and moves the claw in the releasing direction after passing the cutting position of the moving knife. Thread cutting device.   The thread cutting device for a sewing machine according to claim 2, wherein the protruding member of the releasing means comprises a separate member separable from the moving knife.   In the interlocking mechanism, the moving knife or a member that performs a reciprocating rotation operation integrally with the moving knife presses the standby knife or a member that performs a reciprocating rotation operation integrally with the standby knife. 4. The thread cutting device for a sewing machine according to claim 1, wherein only the movement of the moving knife in the forward direction is interlocked with the standby knife. 5. The actuator includes an operation unit that performs a reciprocating movement operation, and connects the operation unit to the moving knife.
5. The actuator according to claim 1, wherein the actuator is controlled so that an operating portion of the actuator can freely move according to an external force while the moving knife is reciprocated by the cam mechanism. The sewing machine thread cutting device according to any one of the preceding claims.

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