JP4337063B2 - Sewing machine with thread trimmer - Google Patents

Description

  The present invention mainly relates to a sewing machine with a thread trimming device applied to a multi-needle cylindrical type sewing machine used for sewing a cylindrical portion such as a neck of a T-shirt, sewing a cuff, or covering. Specifically, it has a cylindrical bed suitable for sewing a cylindrical part, and is arranged at the free end of this cylindrical bed at a plurality of needle drop holes and before and after the needle drop holes orthogonal to the cylinder axis direction. A needle plate having a groove for a cloth feed dog that feeds the cloth in the axial direction is fixed, and a looper is provided at the lower part of the needle plate. The present invention relates to a multi-needle cylinder type sewing machine provided with a thread trimming device that draws and cuts the needle thread and looper thread that are positioned between them.

  The basic configuration of the thread trimming device installed in the above multi-needle cylinder type sewing machine has a thread hook at the tip, and the thread hook crosses the needle drop hole formed in the needle plate. A substantially slanted-shaped movable knife that is reciprocally driven and oscillated along a horizontal plane about the base end side axis, and when this movable knife oscillates in the forward drive, the hook is hooked on the thread hook. Between the fixed knife that cuts the needle thread that is transferred to the side of the needle drop hole of the needle plate by a shearing action with the movable knife, and the cut thread end between the tip of the movable knife And a yarn pinching plate for elastic pinching.

  In the sewing machine with a thread trimming device as described above, the needle thread or the needle thread and the looper thread are cut by the shearing action of the movable knife that swings back and forth and the cutting blade edge of the fixed knife. Therefore, it is a very important technical matter that the shearing force, that is, the sharpness is good and that the good sharpness is not deteriorated over time. As a means for achieving such an important technical matter, in the conventional thread trimmer, an elastic pressing member such as a spring plate that elastically presses the movable knife toward the fixed knife side is attached to the back surface of the fixed knife, and further, the aging of the sharpness is further improved. A movable knife pressing mechanism configured to be able to adjust the elastic pressing force of the elastic pressing member against the movable knife in order to compensate for the deterioration is employed (for example, see Patent Document 1).

  JP 2006-75552 A

  However, in the conventional sewing machine with a thread trimming device that employs the movable knife pressing mechanism configured as described above, the movable knife pressing mechanism itself is an elastic pressing member such as a spring plate, and an attachment member that attaches the elastic pressing member to the back surface of the fixed knife. In addition, a very large number of parts are required, such as elastic pressing force adjustment parts such as long holes and screws, and a thread pinch plate must be similarly installed in a narrow part on the back of the fixed knife to which the pressing mechanism is attached For this reason, there is a problem in that the installation of these many parts is complicated and the installation (assembly) operation itself becomes very difficult. In addition, due to the large number of parts, the elastic pressing force against the movable knife tends to vary due to the accumulation of manufacturing errors and assembly errors for each part. As a result, good and uniform sharpness as expected. In addition, there is a problem that variation is easily generated in the adjustment of the elastic pressing force, and the deterioration of the sharpness over time is unavoidable.

  The present invention has been made in view of the above circumstances, not only can reduce the number of parts, reduce cost and ease of assembly, rationalization, can ensure a good sharpness as expected, And it aims at providing the sewing machine with a thread trimming device which can maintain the favorable sharpness over a long period of time.

The sewing machine with a thread trimming device according to claim 1 of the present invention devised to achieve the above object has a distal end portion curved in a hook shape and has a thread hooking portion on the inner periphery of the curved distal end, and a proximal end portion. A substantially slanted-shaped movable knife that is reciprocally driven and swung along a horizontal plane so that the yarn hooking portion crosses a needle drop hole formed in the needle plate about the axis of A fixed knife that cuts the needle thread and / or looper thread that is hooked on the thread hook and transferred to the side of the needle drop hole of the needle plate by a shearing action with the movable knife when moving. In a sewing machine with a thread trimming device comprising a thread pinching plate that elastically clamps the thread end portion between the tip of the movable knife and a needle that is a part of a reciprocating drive swing path of the movable knife The position along the one side of the back of the plate is below the back of the needle plate at the front and back positions in the cloth feed direction. Portion projecting is formed into, between the back of the upper surface and the needle plate of the belt-shaped female push plate that is passed fixed hung over between the projecting portion to these lower, equal to the thickness of said movable knife or nearly equal slits have a vertical width is formed in a state having a stepped displaced upward with respect to the cutting blade edges of the fixed knife, shearing action between said fixed knife movable knife is go-around swing Only when cutting the needle thread and / or looper thread that has been hooked on the thread hooking portion and transferred to the needle drop hole side, both the front and back surfaces of the movable knife are formed on the back surface of the needle plate and the belt-shaped knife pusher plate. The tip of the movable knife is slidably contacted with the upper surface, and the tip of the movable knife is elastically displaced upward by the step with respect to the cutting blade edge of the fixed knife. It is elastically pressed and guided to the cutting edge. Further, the belt-shaped knife pusher plate has a return guide piece for returning the movable knife, which has come out of the slit and returned to the slit, before the thread is cut by a shearing action with the fixed knife. It is characterized by being connected continuously .

Further, a sewing machine with a thread trimming device according to claim 2 of the present invention devised to achieve the same object as described above for a multi-needle cylindrical type sewing machine is a free end of a cylindrical bed. In addition, a needle plate having a plurality of needle drop holes orthogonal to the cylinder axis direction and a groove for a cloth feed tooth that is arranged before and after the needle drop holes and feeds the cloth in the cylinder axis direction is fixed, A looper that reciprocally swings in the direction intersecting the cloth feeding direction is provided in the cylindrical bed at the bottom of the needle plate, the tip side is curved like a hook, and a thread hook is provided on the inner periphery of the curved tip. And the reciprocating rocking motion path of the looper and the needle so that the distal end thread hooking portion traverses the plurality of needle drop holes around a shaft provided on the back surface of the needle plate on the base end side. A movable knife having a substantially slanted shape that is reciprocally driven and swung along a horizontal plane between the back surface of the plate, When the movable knife of the forward movement swings in the forward direction, a plurality of needle threads and looper threads that are hooked on the thread hook and transferred to the side of the needle drop hole are cut by a shearing action with the movable knife. In a sewing machine with a thread trimming device, comprising: a fixed knife that performs cutting, and a thread pinching plate that elastically clamps the cut thread end between the movable knife and the tip of the movable knife. A portion that protrudes downward from the back surface of the needle plate is formed at the front and rear positions in the cloth feeding direction at a location along one side of the back surface of the needle plate that is a part of the path, and extends between these downward protruding portions. A slit having a vertical width equal to or approximately equal to the thickness of the movable knife is located above the cutting knife edge of the fixed knife between the upper surface of the band-shaped knife pressing plate fixed over the bridge and the back surface of the needle plate. displaced is formed in a state having a step, the friendly Only when cutting the needle thread and / or looper thread that has been reciprocally swung and is hooked on the thread hook by the shearing action with the fixed knife and transferred to the needle drop hole side. Both front and back surfaces of the movable knife are in sliding contact with the back surface of the needle plate and the upper surface of the belt-like knife pressing plate, and the tip of the movable knife is elastically displaced upward by the step relative to the cutting blade edge of the fixed knife, The tip of the movable knife is elastically pressed and guided against the cutting blade edge of the fixed knife with a force corresponding to the elastic return force. A return guide piece for returning the movable knife, which has swung out from the movable knife, into the slit before the yarn is cut by a shearing action with the fixed knife, is integrally provided .

  According to the sewing machine with a thread trimming device according to claims 1 and 2 of the present invention having the above-described characteristic configuration, the reciprocating drive swinging movement path of the movable knife cuts the fixed knife with respect to the back surface of the needle plate. Since it is fixedly regulated by a slit formed at a position closer to the blade edge, that is, at a position having a step above the cutting blade edge of the fixed knife, at the time of thread cutting by shearing action with the fixed knife Only the tip of the movable knife is elastically displaced by the level difference with respect to the cutting knife edge of the fixed knife, and the tip of the movable knife is elastically contacted with the cutting knife edge of the fixed knife with a force corresponding to the elastic return force. Is possible. That is, the slit plays a role of elastically pressing the movable knife toward the fixed knife side, and like the movable knife pressing mechanism in the conventional thread trimmer, the elastic pressing member such as a spring plate and the like, Does not require a large number of parts such as a mounting member to be attached to the back surface and an elastic pressing force adjusting part such as a long hole or a screw, for example, a belt-like shape between the back surface of the needle plate and the portion protruding downward from the back surface of the needle plate The movable knife pressing function for improving the sharpness can be exhibited by using simple processing such as bridging and fixing the knife pressing plate and using very few parts. In addition, the knife pusher plate for demonstrating the movable knife pusher function may be provided at a location slightly away from the thread clamp plate mounting location without concentrating it on the thread clamp plate mounting location on the back of the needle plate. Installation of the push plate and the thread pinch plate is complicated in a narrow space, and the installation work is not complicated.

In addition , when the movable knife advances to capture the needle thread and / or looper thread, the movable knife comes out of the slit and the elastic contact force against the cutting blade edge of the fixed knife is released, so that the conventional movable knife is released. Compared to the case where the tip of the movable knife is always elastically pressed to the fixed knife side using an elastic pressing member such as a spring plate like a knife pressing mechanism, the movable knife has its main threading function reliably demonstrated. The emphasis is on being done, and it is not necessary to place importance on the elastic pressing function to the fixed knife. Therefore, it is possible to reduce the pressing force of the tip threading portion of the movable knife to the fixed knife, reduce wear due to sliding of the movable and fixed knife, and maintain good sharpness over a long period of time. Therefore, not only can the cost be reduced by reducing the number of parts, but also the assembly can be facilitated and rationalized, and the elastic pressing force against the movable knife varies due to the accumulation of parts manufacturing errors and assembly errors. It is easy to ensure the desired sharpness as expected, and a slit with a fixed size such as the vertical width is always fixed without specially adjusting the pressing force. By simply forming the film, it is possible to suppress the deterioration of the sharpness over time as much as possible and to always ensure a good sharpness even in long-term use.

In addition, since the slit is formed between the back of the upper surface of the belt-shaped female push plate that is passed fixed hung over between portions projecting downward from the back surface of the needle plate the needle plate, the needle plate Although the number of parts and the number of processing steps are slightly increased as compared with the case in which the slit is formed in a penetrating state, it is advantageous in terms of processing and assembly.

Further, the belt-shaped knife pusher plate is integrally provided with a return guide piece for returning the movable knife moved out of the slit into the slit before the yarn is cut by a shearing action with the fixed knife. With this, the sliding contact range of the movable knife by the slit is reduced as much as possible to reduce the load applied to the drive mechanism of the movable knife, but the thread is reliably returned to the slit when cutting the thread and the thread cutting function is sharp. Can be exhibited reliably.

Further, in the sewing machine with a thread trimming device according to claim 1 or 2 , as described in claim 3 , by providing an adjusting piece capable of adjusting the elastic end clamping force of the thread end by the thread clamping plate, Regardless of the type of yarn and the number of yarns, the yarn end portion after cutting can be used in a state where it is always securely clamped elastically.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 is a schematic perspective view of an entire sewing machine when applied to a three-needle cylinder type sewing machine as a sewing machine with a thread trimming device according to the present invention, FIG. 2 is an exploded perspective view of components of the thread trimming device, and FIG. FIG. 4A is an enlarged longitudinal sectional view taken along the line AA in FIG. 3, and FIG. It is the B section enlarged view of Drawing 4 (A). This three-needle cylinder type sewing machine M has a sewing machine spindle, a needle drive mechanism and a presser drive mechanism (these are well-known and detailed structure) from the lower part of the machine bed part (sewing machine body) 2 to the front. The cylindrical bed 1 is extended along with the sewing machine arm portion 3 containing the same.

  As shown in FIGS. 1 and 2, the cylindrical bed 1 is formed by being divided into a lower bed portion 1A that opens upward and an upper cover portion 1B that covers the upper opening of the lower bed portion 1A. A plate-like inner cover 30 as shown in FIG. 3 is provided between the lower bed portion 1A and the upper cover portion 1B so as to be sandwiched and fixed. A needle plate 5 is fixed on the free end portion of the lower bed portion 1A of the cylindrical bed 1 via screws 4, and the lower portion of the needle plate 5 is as shown in FIG. 4 (A). The looper 6 and the looper driving mechanism that reciprocally swings in the bc direction intersecting (orthogonal) with the cloth feeding direction (sewing progression direction) a (this is well known, and the detailed structure and description thereof are omitted). And a bed cover 7 surrounding the looper 6 and the looper driving mechanism is provided at the free end of the cylindrical bed 1 so as to be detachable from the front end side.

  A needle bar 8 that is reciprocated up and down and a presser bar 9 that can be moved up and down are supported in a protruding state downward at the tip of the sewing machine arm 3. The three needles 11 are attached in parallel in a direction orthogonal to the cloth feeding direction a through the stopper 10 and the presser foot presses the sewing product against the needle plate 5 at the lower end portion of the presser bar 9. 12 is attached. The needle plate 5 has left and right sides 5a, 5a formed in parallel with the cloth feeding direction a. The needle plate 5 has three needle plates 5 orthogonal to the cylindrical axis direction of the cylindrical bed portion 2. Needle drop holes 13 are formed, and grooves 14 for cloth feed teeth (not shown because they are well-known) for feeding the cloth in the cylinder axis direction are formed on the front and rear sides and the left and right sides of the needle drop holes 13. An adjustment piece formed on the back surface of the needle plate 5 and capable of adjusting the elastic pinching force of the yarn end portion by the movable knife 15, the fixed knife 16, the yarn pinching plate 17, and the yarn pinching plate 17, which will be described later. A thread trimming device 18 having 27 as a main component is mounted.

  3, 5, and 6 show a specific structure of the thread trimming device 18, and the movable knife 15 is a hook that bends in a hook shape on the tip side and hooks a single looper thread LT on the inner periphery of the curved tip. A looper yarn hooking portion 15a and a hook-like needle yarn hooking portion 15b for hooking three needle threads NT are separately formed, and a base end portion 15c of the movable knife 15 is formed on the needle plate 5. The looper 6 is reciprocally swung so that the two hook-shaped thread hooks 15a and 15b cross the three needle drop holes 13 with the screw shaft 19 as the center. When reciprocatingly swinging in the direction of the arrow de in the horizontal plane between the dynamic movement path and the needle plate 5, the needle plate is swung backward to the retracted position shown by the solid line in FIGS. An outer peripheral edge 15d that does not protrude outward from one side 5a parallel to the cloth feed direction a of 5; 5 and 6, when the forward swing is made to the advance position indicated by the phantom line, it is configured in a substantially sloping ball shape having an inner peripheral edge 15 e located outside the cloth feed dog groove 14 of the needle plate 5. Yes.

  As described above, at the front and rear positions in the cloth feeding direction a at the position along the one side 5a of the back surface 5b of the needle plate 5 which is a part of the reciprocating drive swing movement path of the movable knife 15 configured in a substantially slanting shape. Are formed with portions 5c and 5c that protrude slightly downward from the back surface 5b of the needle plate 5, and a band-shaped female push plate 36 is interposed between the protruding portions 5c and 5c downward via screws 37. The slit 38 has a vertical width h that is equal to or substantially equal to the thickness of the movable knife 15 between the upper surface of the band-shaped knife pusher plate 36 and the back surface 5b of the needle plate 5. Is formed.

  The slit 38 is positioned slightly closer to the back surface 5b of the needle plate 5 than the cutting blade edge 16a of the fixed knife 16, that is, slightly above the cutting blade edge 16a of the fixed knife 16 and has a step. Is formed. Therefore, when the movable knife 15 is swung backward to the retracted position shown by the solid line in FIGS. 4 and 5 and the needle thread NT and the looper thread LT are cut by the shearing action with the fixed knife 16. The upper and lower opposing surfaces of the slit 38 (the back surface 5b of the needle plate 5 and the upper surface of the band-shaped knife pressing plate 36) are in sliding contact with both the front and back surfaces of the movable knife 15, specifically, the tip of the movable knife 15, specifically, FIG. As shown in FIG. 2, the hook-shaped looper yarn hooking portion 15a and the needle yarn hooking portion 15b are elastically displaced upward by the step relative to the cutting blade edge 16a of the fixed knife 16, and the elastic return thereof is performed. The yarn hooking portions 15a and 15b are elastically pressed and guided to the cutting blade edge 16a of the fixed knife 16 with a force corresponding to the force.

  Further, the movable knife 15 that has come out of the slit 38 and oscillated forward to the advance position indicated by the phantom line in FIGS. 4 and 5 is located substantially at the intermediate portion of the band-shaped knife push plate 36 from the advance position. A return guide piece 39 for returning to the inside of the slit 38 when the return swinging is integrally provided.

  The fixed knife 16 in the thread trimming device 18 moves backward when the movable knife 15 swings backward from the advanced position shown by the phantom line in FIGS. 5 and 6 to the retracted position shown by the solid line in FIG. When swinging in the direction d from e, one looper thread LT and three loop yarns that are hooked to the hook-like thread hooks 15a and 15b at the tip and transferred to the side of the needle drop hole 13 are transferred. The needle thread NT is cut by a shearing action with the movable knife 15 pressed against the fixed knife 16 side by the action of the slit 38, and the cloth is directed from the blade edge 16a toward the front side in the cloth feeding direction a. A mounting plate portion 16b formed integrally in a state parallel to the feed direction a is fixed to the back surface of the needle plate 5 via a screw member 28.

  The thread pinching plate 17 is elastically pressed and contacted with the lower surface of the movable knife 15 to elastically pinch and guide the swing of the movable knife 15 between the fixed knife 16 and the cut thread. The end is elastically clamped between the tip of the movable knife 15 and has a thread end clamp 17a that is slanted and straight at a position slightly retracted from the blade edge 16a of the fixed knife 16. A mounting plate portion 17b parallel to the cloth feeding direction a is integrally formed from the oblique linear thread end pinching portion 17a toward the front side in the cloth feeding direction a, and the two screw members 32a, It is attached to the back surface of the fixed knife 16 together with the adjusting piece 27 through 32b.

  Further, in the adjusting piece 27, a circular screw hole 27a is formed at a position corresponding to the head of one screw member 32a of the two screw members 32a and 32b, and the other screw member 32b. Is formed with an arc-shaped elongated hole 27b centered on the axis of the one screw member 32a. The screw member 32bb is slightly loosened and the head of the one screw member 32a is used as a fulcrum. By swinging in the direction of the symbol fg, the elastic pinching force of the yarn end portion by the yarn pinching plate 17 can be adjusted.

  On the other hand, a cylinder mounting block (not shown) is fixed to the upper surface of the inner cover 30 corresponding to the proximal end position of the cylindrical bed 1 by welding or the like, and the air cylinder 20 is mounted on the mounting block. The inner cover 30 can be fixedly installed via a screw 33 screwed from the lower surface side. At the tip of the movable rod portion 21 of the air cylinder 20, there is a drive connection link 26 disposed on the inner cover 30 and extending in the cloth feeding direction (sewing progress direction) a in the cylindrical bed 1. The end portion is pivotally connected via a stopper collar 22, a nut 23, a mounting block 24, and a support shaft 25, and the distal end portion of the drive connection link 26 protrudes near the proximal end portion 15c of the movable knife 15. The pin 34 is fitted and connected so as to be relatively rotatable.

  The above-described air cylinder 20 with the movable rod portion 21 and the drive connection link 26 constitute a movable knife driving mechanism. This movable knife driving mechanism is mounted on the inner cover 30 before the inner cover 30 is assembled into the cylindrical bed 1. The inner cover 30 is sandwiched and fixed between the lower bed portion 1A and the upper cover portion 1B of the cylindrical bed 1 without being exposed or protruding sideways from the cylindrical bed 1. It is assembled inside the cylindrical bed 1.

  Next, the sewing and thread trimming action by the three needle cylinder type sewing machine M provided with the thread trimming device 18 configured as described above will be described.

  For example, a cover ring or the like is sewn while the cylindrical portion of the sewing product inserted into the cylindrical bed portion 1 from its free end side is fed in a predetermined cloth feeding direction a via the cloth feeding teeth. When the predetermined sewing is completed, the movable knife 15 of the thread trimmer 18 is slidably guided and fixed so that the front and back surfaces of the movable knife 15 are slidably in contact with the upper and lower surfaces of the slit 38 and the upper surface of the belt-shaped knife pusher plate 36. The knife 16 swings along a certain horizontal plane via the pinching guide action with the thread pinching plate 17, and hook-shaped thread hooks 15 a and 15 b at the tip thereof cross the three needle drop holes 13 in the needle plate 5. 5. After the forward drive swing is made to the advance position shown by the phantom line in FIG. 6, the backward drive swing is made from this advance position to the retreat position shown by the solid line in FIGS. During the backward drive swing, the three needle threads NT passing through the needle drop hole 13 in the vertical direction are hooked on the thread hooking portion 15 b and one looper thread LT locked on the looper 6. Is hooked on the thread hook 15a and transferred to one side of the needle drop hole 13 and the feed dog groove 14.

  When the movable knife 15 swings backward, the movable knife 15 is vertically opposed to the slit 38 that has a step with the front and back surfaces slightly displaced with respect to the cutting blade edge 16a of the fixed knife 16. Since the inside of the slit 38 is swung while being in sliding contact with the back surface 5b of the needle plate 5 and the upper surface of the band-shaped female push plate 36, the hook-shaped looper thread hooking portion 15a and the needle thread at the tip thereof As shown in FIG. 7, the thread hooking portion 15b is elastically displaced upward by the step relative to the cutting blade edge 16a of the fixed knife 16, and the yarn hooking portion 15a and the thread hooking portion 15b are elastically restored by a force corresponding to the elastic return force. 15b is elastically pressed against the cutting blade edge 16a of the fixed knife 16, so that the looper thread LT and needle thread NT that are hooked and transferred by the thread hooks 15a and 15b elastically contact each other. Movable knife 5 and the cutting blade edge 16a of the fixed knife 16 are subjected to a strong shearing action to be sharply cut, and then each of the cut yarn ends is the tip of the movable knife 15 and the yarn of the yarn clamping plate 17 It is elastically pinched between the end pinching portions 17a.

  As described above, since the slit 38 formed on the back surface 5b side of the needle plate 5 serves to elastically press the movable knife 15 against the fixed knife 16 side, the movable knife pressing provided in the conventional thread trimming device is provided. A large number of parts such as an elastic pressing member such as a spring plate such as a mechanism, an attaching member for attaching the elastic pressing member to the back surface of the fixed knife, and an elastic pressing force adjusting component such as a long hole or a screw are unnecessary. Movable to improve the sharpness by using a very simple process and a very small number of parts such as a belt-like female push plate 36 is fixed between the back surface 5b and the protruding portions 5c, 5c of the back surface 5b of the needle plate 5. The knife pressing function can be demonstrated. Further, the fixing position of the knife pressing plate 36 for forming the slit 38 that exhibits the movable knife pressing function is not concentrated on the attachment position of the thread clamping plate 17 on the back surface 5b side of the needle plate 5, but the thread clamping plate 17 Since the attachment of the female pusher plate 36 and the thread pinching plate 17 is not complicated in a narrow space, the assembly work can be facilitated and streamlined. Can be planned.

  In addition, as described above, not only can the cost be reduced by reducing the number of component parts, but also the variation in the elastic pressing force against the movable knife 15 due to the accumulation of manufacturing errors and assembly errors of parts is extremely reduced. Moreover, since the tip thread hooks 15a and 15b of the movable knife 15 are elastically pressed against the cutting blade edge 16a of the fixed knife 16 only during the thread trimming operation, Wear due to sliding will be reduced, and the desired sharpness can be maintained over a long period of time, and even if there is no special adjustment mechanism for pressing force, the vertical width etc. By simply forming the slits 38 of a certain size fixedly, it is possible to suppress the deterioration of the sharpness over time and always ensure a good sharpness even in long-term use.

  The slit 38 may be formed by penetrating the needle plate 5 itself. In particular, as described in the above embodiment, the slit 38 uses the back surface 5b of the needle plate 5 and the band-shaped female push plate 36. Therefore, an advanced processing technique of penetrating and forming a slit in the relatively thin needle plate 5 is unnecessary, and although the number of components is slightly increased, it is advantageous in processing and assembling surfaces.

  Furthermore, in the above embodiment, the adjustment piece 27 is swung in the direction of the arrow fg with the head of one of the mounting screw members 32a as a fulcrum, so The elastic clamping force can be adjusted, and this ensures that the thread end after cutting is always between the movable knife 15 and the thread clamping plate 17 regardless of the type and number of threads. It can be used in a state of being elastically clamped.

  In the above embodiment, the three-needle cylinder type sewing machine M applied to the thread trimming apparatus has been described in detail. However, the two-needle cylinder type, the four-needle cylinder type, and the single needle cylinder are described. Of course, the present invention may be applied to a type sewing machine, and may be applied to a thread trimming device in various forms of sewing such as flat stitching.

  In the above embodiment, the looper thread hooking portion 15a and the needle thread hooking portion 15b are separately formed on the inner periphery of the curved tip of the movable knife 15, but one hook-like thread is described. You may comprise so that a needle thread | yarn and a looper thread | hook may be hooked on a hanging part.

  Further, as the reciprocating drive mechanism of the movable knife, the one described in the above embodiment is the most effective because it simplifies the configuration, reduces the cost, and facilitates the assembly work. A drive mechanism with any configuration may be used.

It is a schematic perspective view of the whole sewing machine at the time of applying to a three needle cylinder type sewing machine as a sewing machine with a thread trimming device concerning the present invention. It is a disassembled perspective view of the component of the thread trimming device in a sewing machine same as the above. It is a top view which crossed a part of sewing machine same as the above and centered on the thread trimming device vicinity which is the principal part. (A) is an enlarged vertical sectional view taken along line AA in FIG. 3, and (B) is an enlarged view of a portion B in FIG. 4 (A). It is an enlarged plan view of the principal part containing the same thread trimming apparatus. It is an expanded bottom view of the principal part containing a thread trimming apparatus same as the above. It is sectional drawing of the principal part explaining operation | movement of the movable knife in the same thread trimming apparatus.

DESCRIPTION OF SYMBOLS 1 Tubular bed 1A Lower bed part 1B Upper cover part 5 Needle plate 5b Back side of needle plate 6 Looper 13 Needle drop hole 14 Groove for cloth feed dog 15 Movable knife 15a, 15b Hook-shaped thread hook part 16 Fixed knife 16a Cutting edge 17 Thread clamp plate 18 Thread trimming device 27 Adjustment piece 36 Band-shaped knife pusher plate 38 Slit 39 Return guide piece a Cloth feed direction (sewing advance direction)
M Three needle cylinder type sewing machine LT Looper thread NT needle thread

Claims (3)

The tip side is curved like a bowl and has a thread hook on the inner periphery of the bent tip, and the thread hook crosses the needle drop hole formed in the needle plate about the base end axis. A substantially slanting-shaped movable knife that is reciprocally driven along and reciprocally driven, and when this movable knife swings forwardly, it is hooked on the thread hook and transferred to the side of the needle drop hole of the needle plate. A fixed knife that cuts the needle thread and / or looper thread by a shearing action with the movable knife, and a thread clamping plate that elastically clamps the cut thread end between the tip of the movable knife. In a sewing machine with a thread trimming device,
Portions extending downward from the back surface of the needle plate are formed at front and rear positions in the cloth feed direction at locations along one side of the back surface of the needle plate that forms part of the reciprocating drive swing path of the movable knife. between the upper surface and the rear surface of the needle plate of the passing fixed strip-shaped female push plate bridged over between the projecting portion of the slit to have a thickness equal to or nearly equal top and bottom widths of the movable knife is fixed knife The movable knife is reciprocally swung and hooked on the thread hook by the shearing action between the fixed knife and the needle. Only when cutting the needle thread and / or looper thread that has been transferred to the fall hole side, the front and back surfaces of the movable knife are in sliding contact with the back surface of the needle plate and the upper surface of the belt-shaped knife pusher plate, and the tip of the movable knife Part is the step with respect to the cutting blade edge of the fixed knife Only resiliently displaced upward, is configured such that its front end portion of the movable knife with a force corresponding to the elastic return force is guided pressing elastically the cutting blade edges of the fixed knife,
Further, the belt-shaped knife pusher plate is integrally provided with a return guide piece for returning the movable knife, which has come out of the slit and returned to the slit before the yarn is cut by a shearing action with the fixed knife. A sewing machine with a thread trimming device. At the free end of the cylindrical bed, there are a plurality of needle drop holes perpendicular to the cylinder axis direction and a groove for a cloth feed tooth that is arranged before and after the needle drop holes and feeds the cloth in the cylinder axis direction. The needle plate is fixed, and a looper that reciprocally swings in the direction intersecting the cloth feeding direction is provided in the cylindrical bed at the bottom of the needle plate. The looper reciprocates so that the distal end thread catching portion crosses the plurality of needle drop holes with a thread catching portion around the periphery and a base provided on the back surface of the needle plate on the base end side. An approximately slanted-shaped movable knife that is reciprocally driven and oscillated along a horizontal plane between the oscillating movement path and the back surface of the needle plate, and when the movable knife oscillates in the forward drive direction, the movable knife is pulled to the thread hook. A plurality of needle threads and looper threads that are hung and transferred to the side of the needle drop hole are connected to the movable knife. A fixed knife for cutting by shearing action, the thread cutting device with a sewing machine formed by and a yarn pinching plate elastically sandwiched between the tip portion of the movable knife to cut yarn ends,
The portion projecting downward from the back surface of the needle plate is formed in the longitudinal position of the cloth feeding direction of 箇 stations along the one side of the rear surface of the part to become the needle plate of the reciprocating drive rocking motion path of the movable knife, A slit having a vertical width equal to or approximately equal to the thickness of the movable knife is fixed between the upper surface of the band-shaped knife pressing plate fixed over the projecting portions downward and the back surface of the needle plate. It is formed in a state having a step by being displaced upward with respect to the cutting blade edge of the knife , and the movable knife is swung backward and is hooked on the thread hook by the shearing action with the fixed knife. Only when cutting the needle thread and / or looper thread that has been transferred to the needle drop hole side, the front and back surfaces of the movable knife are in sliding contact with the back surface of the needle plate and the upper surface of the belt-shaped knife pusher plate. The tip is the cutting blade edge of the fixed knife Elastically displaced upwardly by the difference, which is configured to be resiliently pressed against the guide the cutting blade edges of the tip fixed knife force at movable knife corresponding to the elastic restoring force,
Further, the belt-shaped knife pusher plate is integrally provided with a return guide piece for returning the movable knife, which has come out of the slit and returned to the slit before the yarn is cut by a shearing action with the fixed knife. A sewing machine with a thread trimming device. The thread trimming machine sewing machine according to claim 1 or 2, further comprising an adjustment piece capable of adjusting an elastic end clamping force of the yarn end by the thread clamping plate.

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