JP5041284B2 - Sewing machine thread trimmer - Google Patents

Description

The present invention relates to a thread trimming device for a sewing machine used for cutting a needle thread and a looper thread after completion of a predetermined sewing operation using, for example, a flat stitch sewing machine or a double chain stitch sewing machine. For more information, has a thread catching portion for catching the needle thread and looper thread in the tip, room access to the rear side of the advance output and movement trajectory of the forward position and the looper has between its thread catching portion of the needle plate and the looper A movable knife capable of reciprocating between the retracted position, a reciprocating oscillating drive lever for reciprocatingly driving the movable knife between the two positions, and the movable knife after completion of a predetermined sewing operation. A fixed knife that cuts the needle thread and the looper thread captured by the thread trapping portion by a cooperative action with the movable knife, and the cut needle thread and the looper thread when moving forward from the forward position to the backward position. This invention relates to a thread trimming device for a sewing machine comprising a thread pinching plate that elastically clamps the end of the sewing machine between the end of the movable knife and the tip of the movable knife.

In the thread trimming device of the sewing machine configured as described above, in order to shorten the remaining length of the needle thread and the looper thread in the sewing product when the thread is cut after the sewing operation is finished, the movable knife, the fixed knife and the thread In order to move the pinch plate to the forward advance position close to the needle plate and the looper, and to prevent the fixed knife etc. from interfering with the operation of the looper during the next sewing operation after thread cutting, It is necessary to move the fixed knife, the movable knife and the thread clamp plate from the advanced position at the time of cutting the thread to the retracted position.

  Conventionally, as a means for moving to the rearward retracted position after the thread cutting, a knife holding base for holding a movable knife, a fixed knife and a thread clamp plate is provided between the forward and backward positions for thread cutting of the movable knife. It has been configured to recede to the retracted position linearly or almost linearly along the extended line of the reciprocating drive movement path (see, for example, Patent Documents 1 and 2).

  JP 2005-168563 A   Japanese Utility Model Publication No. 63-10149

However, in the conventional thread trimming apparatus in which the linear or substantially linear backward moving means is employed as described above, even when moved to the retracted position, as shown in FIG. 51 and the thread pinching plate 52 (hereinafter also referred to as a movable knife or the like) are in a positional relationship in which the distal end portion (left end portion) is very close to the left-right reciprocating motion trajectory (indicated by an arrow 54) of the looper 53. Further, since the looper yarn L whose cut end portion is elastically sandwiched between the distal end portion of the movable knife 50 and the yarn pinching plate 52 is stretched in a state of being overlapped with a substantially upper portion of the looper 53, the looper yarn L The triangular area to be formed becomes very small, and depending on the type of thread used, the needle (not shown in FIG. 7) does not drop into the triangular area of the looper thread L when the next sewing operation starts, Can cause Was Tsu.

Further, the looper in a state where the movable knife 50 or the like is moved to the retracted position, the looper 53, as shown in FIG. 8, is stopped in the rightmost its lateral reciprocating path 54 to the looper tip near the yarn hole 53a When the thread L is passed, the thread hole 53a is located in a very narrow and cramped portion between the tip of the movable knife 50 and the needle plate 56, and therefore, the tip of the movable knife 50 and the like. There is also a problem that the needle plate 56 becomes an obstacle and the threading operation through the thread hole 53a is difficult.

The present invention has been made in view of the above circumstances, when allowed to move to the retracted position, and reliably to form a large triangular area by the looper thread, the said triangle area reliably needle at the next sewing operation start It can be lowered to prevent the occurrence of stitch skipping, and the looper thread can be easily threaded through the thread hole, and it is durable with no rattling or damage due to local load. It is an object of the present invention to provide a thread trimming device for a sewing machine that can improve the performance.

In order to achieve the above object, a thread trimming device for a sewing machine according to the present invention has a yarn catching portion for catching a needle thread and a looper yarn at the tip, and the yarn catching portion advances between a needle plate and a looper. a movable knife that can reciprocate over between the advanced position and a retracted position retracts to the rear side of the moving path of the looper, and a reciprocating swinging reciprocating drive moves across the movable knife between the two positions When the movable knife moves backward from the forward movement position to the backward movement position after the end of a predetermined sewing operation, the needle thread and the looper thread captured by the thread capturing section cooperate with the movable knife. In a thread trimming device for a sewing machine, comprising: a fixed knife that cuts by a needle; and a thread pinching plate that elastically clamps the end of the cut needle thread and looper thread between the tip of the movable knife. The stand has the movable knife, fixed knife and thread clamp. Two long and short swings that can swing and displace the knife holding base for holding the plate between a forward advance position close to the needle plate and the looper and a retreat position obliquely rearward than that. A quadruple link mechanism comprising a link is provided, and when the drive lever further swings backward after the yarn is cut by the cooperative action of the movable knife and the fixed knife, the drive lever The four-link mechanism is operated in synchronization with a long rocking link so that the knife holding base is rocked and displaced from the advanced position to the retracted position.

  According to the thread trimming device of the sewing machine according to the present invention having the above-described characteristic configuration, the reverse drive is moved from the forward position to the reverse position through the swing of the reciprocating swing drive lever after a predetermined sewing operation. After the needle thread and the looper thread are cut by the cooperative action of the movable knife and the fixed knife, the four-link mechanism is operated in synchronization with the further backward swing of the drive lever. The movable knife, fixed knife and thread clamp plate after thread cutting through the holding base are swung to the retracted position obliquely backward with respect to the needle plate and looper, that is, offset to the obliquely backward position with respect to the needle plate and looper. Can be made. Therefore, the looper thread whose end is elastically sandwiched between the tip of the movable knife and the thread clamp plate after thread cutting does not overlap the looper substantially directly above the looper, and is slanted between the looper and the thread clamp plate. Therefore, it is possible to reliably form a large triangular area with the looper thread, and to ensure that the needle is in the triangular area of the looper thread at the start of the next sewing operation, regardless of the type of thread used. It is possible to reliably prevent the occurrence of stitch skipping and to perform good sewing as prescribed.

  In addition, because the movable knife, the fixed knife and the tip of the thread clamp plate are offset with respect to the needle plate and the looper, a sufficiently wide space can be secured around the thread hole of the looper on the left and right and up and down. The operation of passing the looper thread through the thread hole can be performed very easily without being interrupted by the needle plate, the movable knife, or the like.

  In addition, since the quadruple link mechanism consisting of two long and short rocking links is used for offset movement to the retracted position obliquely rearward of the knife holder, the guiding action by sliding between the long hole and the screw engaged therewith Compared to the case of offset movement, the occurrence of backlash is very small, and the sliding guide parts such as screws are overloaded and may be damaged or deformed. As a result, the durability of the entire apparatus including the movable component can be improved, and the elastic pinching function of the thread end after cutting can be stabilized.

Oite the thread cutting device of a sewing machine according to the present invention, between the intermediate portion of the long swing link of the quadruplicate link mechanism and the device mount, the swinging displacement to the advanced position of the female holder When providing a stopper mechanism that stops and allows adjustment of the stop position (Claim 2), the position of the movable knife or the like that has advanced to the advance position is reliably defined, and wear or the like occurs. Adjustment can be easily performed.

Further, Oite the thread cutting device of a sewing machine according to the present invention, wherein the pivot portion of the female holder of a short swing link of quadruplicate link mechanism, adjust the position before and after with respect to the female holder of the needle plate and the looper When a possible eccentric spacer is interposed (Claim 3), the advancing position and the retracting position of the tip of the movable knife or the like with respect to the needle plate and the looper can be easily adjusted to achieve a predetermined thread cutting performance and thread end clamping performance. It can be used in a state where it is always exerted reliably and stably.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an exploded perspective view of components constituting a thread trimming device 40 of a sewing machine according to the present invention, and FIG. 2 is a plan view of a main part in a state where the components of the thread trimming device 40 are assembled. The thread trimming device 40 is viewed from the side of the sewing manufacturer, and includes a throat plate having a needle drop portion 31 (which is well known and not shown), and a loop-like movement locus 32 (in a plan view) below the throat plate ( As shown in FIG. 5, it is arranged on the right side of the looper 33 that reciprocally swings left and right, and is fixed to the inside of the sewing machine bed (not shown) via the device mounting base 1.

The thread trimming device 40 has a hook-shaped thread catching portion 2a for catching a needle thread and a looper thread L (see FIG. 5) at the tip, and this thread catching portion 2a advances between the needle plate and the looper 33. 3 can be reciprocated in the left-right direction indicated by arrows ab between the forward position shown in FIG. 3 and the backward position shown in FIG. 2 retracted to the right (backward) side of the movement locus 32 of the looper 33. An intermediate part in the longitudinal direction is pivotally supported by a movable knife 2 and a device mounting base 1 via a step screw 3, and an extension drive source (not shown) such as a cylinder connected to one end in the longitudinal direction. Reciprocating rocking that can reciprocate in the left and right directions indicated by arrows cd with the axis of the stepped screw 3 as a fulcrum, and that causes the movable knife 2 to reciprocate between both positions by the reciprocating driving rocking. The movable drive lever 4 and the movable knife 2 are moved to the front of FIG. When moving backward from the position to the retracted position of FIG. 2, the fixed knife 5 that cuts the needle thread and the looper thread L captured by the thread capturing section 2 a by the cooperative action with the movable knife 2 is cut. A thread clamping plate 6 that elastically clamps the end portions of the needle thread and the looper thread L between the distal end portion of the movable knife 2 and the distal end portion of the thread clamping plate 6 is elastically pressed toward the movable knife 2 side. A thread clamping plate pressing spring 7 and a thread clamping plate pressing spring adjusting piece 8 disposed below the thread clamping plate pressing spring 7 are provided.

  A movable knife base 10 is fixed to the lower surface of the right end of the movable knife 2 via a screw 9. The movable knife base 10 is slidably contacted and supported on the upper surface of a knife holding base 13 fixed to the apparatus mounting base 1 via step screws 11 and screws 12. The drive lever 4 includes a long hole 4a formed at the other longitudinal end of the drive lever 4 and a step screw 14 inserted from below into a long groove 13a formed linearly in the left-right direction in the knife holding base 13. 4, the movable knife 2 is moved in the left-right direction ab along the long groove 13a in conjunction with the reciprocating drive swing of the drive lever 4 in the left-right direction cd. It is configured to move back and forth linearly.

  The fixed knife 5 is arranged on the upper part of the movable knife 2 and holds the knife through two right and left screws 16 penetrating the left and right elongated holes 5a and 6a formed in the fixed knife 5 and the thread pinching plate 6. It is supported on a fixed knife guide 15 fixedly held on the table 13. The middle part of the two left and right screws 16 penetrates through the long holes 5a and 6a and the knife holding base 13 and projects downward, and the projecting lower end thereof is substantially the middle part of the thread pinch plate pressing spring adjusting piece 8. An adjustment screw 17 that is screwed and connected is provided. By adjusting the tightening amount of the adjustment screw 17, the base end portion is supported by a screw 18 that penetrates the female holding base 13 and protrudes downward. The free end portion of the thread pinch plate pressing spring adjusting piece 8 is moved up and down to press the thread pinch plate pressing spring 7 against the thread pinching plate 6, and thus the tip portions of the thread pinching plate 6 and the movable knife 2. The elastic pinching force at the end of the cut yarn due to is adjustable. In addition, a long hole 7a in the left-right direction is formed in the right end portion of the thread pinch plate pressing spring 7, and the thread pinching spring mounting plate 20 is connected to the knife holding base 13 via a screw 19 that passes through the long hole 7a. The front and rear positions of the thread pinch plate pressing spring 7 can be adjusted by loosening the screw 19.

  The device mount 1 is provided with two long and short links 21 and 22 on the right and left sides of the drive lever 4. One end in the longitudinal direction of these two long and short links 21 and 22 is pivotally supported on the apparatus mounting base 1 through step screws 23 and 24 so as to be swingable to the left and right around the screw shaft centers. The other ends in the longitudinal direction of the swing links 21 and 22 are pivotally connected to the front and rear two places of the female holding base 13 via the stepped screw 11 and the screw 12 to constitute a four-link mechanism. The movable knife 2, the fixed knife 5, the fixed knife guide 15, the thread pinching plate 6, the thread pinching plate pressing spring 7 and the thread pinching plate are moved by the left and right swinging of the two long and short swing links 21 and 22 constituting the linkage mechanism. As shown in FIGS. 2 and 3, the knife holding base 13 that holds the pressing spring adjusting piece 8 is located in the forward (leftward) position close to the needle plate and the looper 33, and FIGS. As shown in FIG. It is swung displaceably configured over between a retracted position to the right rear).

  A bulging portion 21b that bulges toward the drive lever 4 is formed on the left side of the intermediate portion of the long swing link 21 constituting the four-link mechanism, and the movable knife 2 and the fixed knife 5 When the drive lever 4 is further swung backward in the right direction d after the yarn is cut by the cooperative action, the drive lever 4 comes into contact with the bulging portion 21b of the long rocking link 21 to cause the rocking link 21 to move. By pushing, the two oscillating links 21 and 22 of the four-link mechanism are oscillated in synchronization with the drive lever 4, and the knife holding base 13 is moved from the advanced position shown in FIGS. 6 through the route indicated by ef, and when the thread is cut after the next sewing operation, the drive lever 4 swings in the left direction c as shown in FIG. 2 through the route indicated by the arrow ef, and swing back to the advanced position shown in FIGS. It is configured to be.

Further, between the intermediate portion of the long swing link 21 constituting the four-link mechanism and the device mounting base 1, the swing displacement of the knife holding base 13 to the advance position is stopped, and A stopper mechanism that can adjust the stop position is provided. Specifically, a long hole 21a centering on the axis of the step screw 3 is formed at an intermediate portion of the long swing link 21, and a screw 25 and a washer 26 are attached to the device mounting base 1 in the long hole 21a. via, for example eccentric shaped stepped portion of the fixed stepped spacer 27 is fitted to and become, the eccentric shaped step portion to the advanced position of the long said by abutting the right end edge of the hole 21a knife holder 13 swings is stop, and, by rotating the stepped spacer 27 about the axis of the screw 25, adjustable the stopper mechanism is configured to the advanced limit position by the eccentric-shaped step portion .

  Further, a coil spring 29 is provided between the short swing link 22 constituting the four-link mechanism and the apparatus mounting base 1 so as to swing the biasing base 13 to the advanced position. In addition, an eccentric spacer 28 is interposed between the screw 12 for pivotally connecting the other end of the short swing link 22 to the female holding table 13 and the female holding table 13. The eccentric spacer 28 is connected to the screw 12. The advance position and the retracted position of the knife holding base 13 with respect to the needle plate and the looper 33 can be finely adjusted.

  Next, the yarn cutting operation, the subsequent retracting operation, and the next sewing operation of the yarn cutting device 40 configured as described above will be described.

Immediately after the end of the predetermined sewing operation, as shown in FIG. 2, the knife holding base 13 holding the movable knife 2, the fixed knife 5, the thread clamp plate 6 and the like is in front of the needle plate and the looper 33 (leftward). ) Has been moved to the advance position. In this state, the movable knife base 10 is linearly moved in the left direction a along the long groove 13a of the knife holding base 13 as the drive lever 4 is driven to swing in the left direction c. as shown in FIG. 3, the thread catching portion 2a of the distal end is forward stroke moved to the advanced position that advances between the needle plate and the looper 33. Thereafter, as the drive lever 4 moves backward in the right direction d, the movable knife 2 linearly moves backward in the right direction b along the same locus as that in the forward movement. The needle thread and the looper thread L captured by the thread capturing section 2a immediately before returning to the advanced position shown in FIG. 2 are cut by the cooperative action with the fixed knife 5, and each of the cut thread ends is a movable knife. 2 is elastically clamped between the tip of 2 and the thread clamp plate 6. At the time of this thread cutting, since the movable knife 2, the fixed knife 5 and the thread clamp plate 6 are in the advanced position close to the looper 33, the remaining length of the needle thread and the looper thread L in the sewing product is shortened, and good sewing is performed. It can be finished.

  After the above-described thread cutting and thread end clamping action, the drive lever 4 is continuously swung backward in the right direction d. During the backward swing, the drive lever 4 abuts against the bulging portion 21b of the long swing link 21 and pushes the swing link 21, so that the two swing links 21 and 22 of the four-link mechanism are coiled. The knife holding base 13 is swung rightward against the urging force of the spring 29, and the knife holding base 13 passes through the route ef shown in FIG. Oscillating displacement to the retracted position diagonally right rear with respect to 33, that is, offset to the diagonally right rear position with respect to the needle plate and looper 33.

  The next sewing operation is started in the state retracted to the offset position. At this time, as shown in FIG. 5, the distal ends of the movable knife 2, the fixed knife 5, the thread clamp plate 6, and the like are separated diagonally right rear with respect to the motion locus 32 of the looper 33. There is no possibility of interfering with the operation of the looper 33 or the like.

  In addition, the looper yarn L whose end is elastically sandwiched between the tip of the movable knife 2 and the yarn clamping plate 6 in accordance with the above-described yarn cutting is located substantially above the looper 33 as shown in FIG. A large triangular area E is formed by the looper thread L because the looper thread L and the loop end of the movable knife 2 and the thread end clamped by the thread clamping plate 6 are slanted without overlapping. It is surely formed. Therefore, regardless of the type of looper thread L to be used, at the start of the next sewing operation, the needle descending toward the needle drop portion 31 is reliably transferred to the triangular area E of the looper thread L to prevent the occurrence of skipping. Good sewing can be performed as prescribed.

  In addition, in a state where the distal ends of the movable knife 2, the fixed knife 5 and the thread clamp plate 6 are offset with respect to the needle plate and the looper 33, there is a sufficiently wide space around the thread hole of the looper 33 in the left and right and up and down directions. Therefore, the operation of passing the looper thread L through the thread hole can be performed very easily without being interrupted by the needle plate, the scalpels 2, 5 and the like.

  Further, when the knife holding base 13 is offset and moved to the retracted position diagonally right rear, a four-link mechanism comprising two long and short rocking links 21 and 22 is used. Compared to the case where the offset movement is performed by the guide action by sliding, the support 13 is firmly supported to reduce the occurrence of backlash and is concentrated on the sliding guide parts such as screws. The possibility of overloading and damage or deformation of the yarn can be greatly reduced, so that the durability of the entire yarn trimming device 40 can be improved and the elastic pinching function of the yarn end after cutting can be stabilized. Can be achieved.

  The thread trimming device of the present invention can be particularly effectively applied as a thread trimming device in a flat stitch sewing machine or a double chain stitch sewing machine, but may be applied to a thread trimming device in various other types of sewing machines. Of course.

  Moreover, in the said embodiment, the bulging part 21b which bulges to the drive lever 4 side is formed in the left side part of the intermediate part of the long rocking | fluctuation link 21 which comprises a quadruple link mechanism, This bulging part 21b Although the description has been made with the driving lever 4 contacting and pushing the long swing link 21, the bulging portion 21 b is not necessarily required, and the drive lever 4 is directly contacted with the left side portion of the swing link 21. Alternatively, a protrusion or a pin that contacts the swing link 21 may be provided on the drive lever 4 side.

It is a disassembled perspective view of the component which comprises the thread trimming device of the sewing machine which concerns on this invention. It is a top view of the principal part in the state in which the component parts of the same thread trimming device were assembled. It is a top view of the principal part which shows the state which the movable knife in the same thread trimming apparatus advanced to the advance position. It is a top view of the principal part which shows the state which the movable knife etc. of the thread trimming apparatus same as the above retracted to the retracted position. It is a top view of the principal part which shows the tension | tensile_strength state etc. of a looper thread | yarn when the movable knife etc. of the thread trimming apparatus same as the above retracted to the retracted position. It is a top view of the principal part explaining the advance / retreat route of the knife holding stand and movable knife of the same thread trimmer. It is a perspective view of the principal part which shows the positional relationship of a movable knife etc. and a looper when the movable knife etc. in the conventional thread trimming apparatus retracted to the retreat position. It is a perspective view of the principal part which shows the positional relationship of a movable knife etc. and a looper when the movable knife etc. in the conventional thread trimming apparatus have retracted to the retreat position and the looper has moved to the rightmost end.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Device mounting base 2 Movable knife 2a Thread catcher 4 Oscillating drive lever 5 Fixed knife 6 Thread clamp plate 13 Female holding base 21 Long oscillating link 22 Short oscillating link 28 Eccentric spacer 33 Looper 40 Thread trimmer L Looper thread

Claims (3)

It has a thread catching part that catches the needle thread and looper thread at the tip part, and the thread catching part has advanced between the needle plate and the looper, and the retracted position retracted to the rear side of the movement locus of the looper. A movable knife capable of reciprocating between the two positions, a reciprocating oscillating drive lever for reciprocatingly driving the movable knife between the two positions, and the movable knife retracts from the forward position after a predetermined sewing operation. A fixed knife that cuts the needle thread and the looper thread captured by the thread trapping portion by a cooperative action with the movable knife, and an end of the cut needle thread and the looper thread when moving forward to a position. In a thread trimming device for a sewing machine comprising a thread pinching plate that elastically clamps between the tip of the movable knife,
The device mounting base has a knife holding base for holding the movable knife, the fixed knife and the thread pinching plate between a forwardly advanced position close to the needle plate and the looper and a retracted position obliquely backward than that. A quadruple link mechanism comprising two long and short rocking links that can be rocked and displaced between them, and the drive lever after the yarn is cut by the cooperative action of the movable knife and the fixed knife. At the time of reverse swing, the drive lever comes into contact with the long swing link of the four-link mechanism so that the four-link mechanism is operated synchronously to swing and displace the knife holding base from the advanced position to the retracted position. A thread trimming device for a sewing machine, characterized by being configured. Between the intermediate portion and the device mount a long swing link of the quadruplicate linkage, to stop swings to the advanced position of the female holder, and can be adjusted its stop position The sewing machine thread trimming device according to claim 1, wherein the stopper mechanism is provided.   The eccentric spacer which can adjust the front-back position with respect to the needle plate and looper of the said female holding base is interposed in the pivotal support part to the female holding base of the short swing link of the four-link mechanism. The thread trimming device of the description sewing machine.

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