JP2006075552A - Sewing machine with thread cutter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a thread cutting mechanism having no projection from a needle plate, dispensing with the formation of a side swelling part on a cylindrical bed, easily and smoothly inserting a cylindrical portion in a cylindrical bed, performing a predetermined sewing, distributing a cutting load, and constantly providing superior cutting performance for a long period of time. <P>SOLUTION: A blade edge 16a of a fixed knife 16 and a free end 17a of a thread clamp plate 17 constituting a thread cutter 18 are formed diagonally linearly long along an inclination direction gradually separating from a cloth feed groove 14 toward the rear side of the cloth feed direction (a), so that the swinging across the full reciprocating drive swinging range of a movable knife 15 is clampedly guided between the fixed knife 16 and the thread clamp plate 17 while changing the contact point with the movable knife between a tip thread hanging part 15a and its base end part according to the reciprocating drive swinging of the movable knife 15. The fixed knife 16 and the thread clamp plate 17 are fixed to the rear face of the needle plate 5 in a state not to outward project from one side of the needle plate 5 having both sides 5a parallel to the cloth feed direction (a). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sewing machine with a thread trimming device that is applied to sewing of a cylindrical portion such as a neck of a T-shirt, sewing of a cuff, or covering. Specifically, it has a cylindrical bed suitable for sewing a cylindrical part, and feeds the needle end holes and the cloth in the cylindrical axis direction to the free end of the cylindrical bed perpendicular to the cylindrical axis direction. A needle plate having a groove for the cloth feed dog is fixed, and a looper is provided at the lower portion of the needle plate, and a needle thread located between the needle plate and the looper after sewing is provided on the side of the needle plate. The present invention relates to a multi-needle cylinder type sewing machine provided with a thread trimming device that pulls a looper thread to the side and cuts it.

  This type of thread trimming device in a multi-needle cylinder type sewing machine has a tip portion that is curved in a hook shape and has a thread catching portion on the inner periphery of the curved tip. A movable knife that is reciprocally driven and swung in a horizontal plane so as to cross the hole, and a plurality of needles that are hooked on the tip thread hook and transferred to the side of the needle drop hole when the movable knife is reciprocally swung. A fixed knife that cuts the thread and looper thread by a shearing action between the movable knife and a movable knife that comes into contact with the movable knife and elastically sandwiches and guides the swing of the movable knife between the knife and the knife. And a thread pinching plate capable of elastically holding the thread end part between the movable knife front end part.

  In a sewing machine with a thread trimming device comprising the above-described components, conventionally, a mounting base is provided on the side portion of the needle plate, and a movable knife whose tip is curved like a hook on the vertical axis provided on the mounting base. The yarn hooking portion that supports the base end portion and has the movable knife formed on the inner periphery of the curved distal end is configured to be capable of reciprocating and swinging in a horizontal plane so that it crosses a plurality of needle drop portions. It is known that a strip-shaped fixed knife and presser spring (thread pinching plate) are arranged and fixed in a state where the edge of the blade and the free end of the spring face the needle thread passing through the needle drop hole in the vicinity of the needle plate. (For example, refer to Patent Document 1).

  The base of the movable knife with a hook knife (thread hook) at the back of the needle plate fixed to the top of the free end of the cylindrical bed is adjacent to the groove for the cloth feed dog The movable knife is pivotally attached to the position where it can be pivoted back and forth along the horizontal surface of the back surface of the needle plate, and the fixed knife and clamp spring (thread pinching plate) are arranged on the back surface of the needle plate in front of the cloth feed dog groove. ) With the blade edge and spring free end edge positioned linearly parallel to the cloth feed direction, and the rotation of the movable knife is not obstructed by the needle plate and part of the cylindrical bed. Also known are those that bulge laterally (see, for example, Patent Document 2).

  Japanese Utility Model Publication No. 1-79477   No. 7-18392

  In this type of sewing machine with a thread trimmer, the movable knife is smooth and stable along a certain horizontal plane without fluctuation over its entire reciprocating drive swing range so that troubles such as contact and collision with other parts do not occur. It is important that the movable knife be swung well. For this purpose, means for elastically holding the movable knife between the fixed knife and the thread clamp plate (referred to as a presser spring) is used to guide the swing. It has been.

  In adopting such a pinch guide means, in the former conventional example shown in Patent Document 1, the pinch guide point of the fixed knife and the thread pinch plate with respect to the movable knife changes according to the swing of the movable knife. Using a strip-shaped fixed knife and a thread clamp plate with a small blade edge width and a free end edge width so that the blade edge and the free end edge of the thread clamp plate are sequentially moved from the free edge of the blade edge to the proximal end portion thereof. It was arranged in a posture along the inclined direction so that the full length direction was gradually separated from the needle drop hole of the needle plate toward the base end side. It is necessary to provide a mounting base on the side portion of the needle plate separately from the needle plate in order to largely protrude into the portion and to fix and support the protruding base end portion. As a result, not only the number of parts and assembly man-hours are increased, but also the base end portion of the mounting base, the fixing knife and the thread clamp plate protrudes to one side of the cylindrical bed, and the protruding portion is When trying to fit inside the shaped bed, a part of the tubular bed bulges out to the side. Therefore, when inserting the cylindrical part of the product to be sewn into the cylindrical bed from its free end side and performing the predetermined sewing, the cylindrical part is caught on the protruding part or the bed bulging part, etc. As a result, there is a problem that it is difficult to perform predetermined sewing reliably and smoothly. Therefore, the minimum diameter of the cylindrical portion that can be sewn is naturally limited, and the applicable range is narrow accordingly.

  Moreover, in the latter conventional example shown in Patent Document 2, it is not necessary to use a mounting base separate from the needle plate, and the number of parts and assembly man-hours can be reduced as compared with the former conventional example. Although it is possible, since the needle plate and a part of the cylindrical bed are bulged laterally so as not to hinder the movement of the movable knife, the cylindrical part of the sewing product is placed on the cylindrical bed. There is a problem similar to the former example of the former, such as being caught when inserted from the free end side and performing the predetermined sewing, the minimum diameter of the cylindrical part that can be sewn is naturally limited, the former example of the former The application range is narrow as well.

  In addition, in both the former and the latter conventional examples, a plurality of needle threads and looper threads that are hooked by the thread hook of the movable knife and transferred to the side are cut at once with the narrow blade edge of the fixed knife. Therefore, the cutting load is very large, the blade edge wears out in a short period of time (so-called blade spillage) or deforms, resulting in reduced sharpness and frequent replacement of the fixed knife. There was a common problem of becoming.

  The present invention has been made in view of the above-described circumstances, and each component is accommodated within the width of a standard throat plate that has been generally used, and a part of the cylindrical bed is inflated laterally. It is not necessary to form a protruding part, and even a small-diameter cylindrical part can be easily and smoothly inserted into the cylindrical bed without being caught, and can be sewn in a predetermined manner. An object of the present invention is to provide a sewing machine with a thread trimming device that can always ensure a sharp thread cutting function even when used for a long time without replacement.

  In order to achieve the above object, a sewing machine with a thread trimming device according to the present invention has a plurality of needle drop holes and a front and rear sides of the needle drop holes at a free end of a cylindrical bed perpendicular to the cylinder axis direction. A needle plate having a groove for a cloth feed tooth that is arranged and feeds the cloth in the cylinder axis direction is fixed, and reciprocally swings in a direction intersecting the cloth feed direction in a cylindrical bed below the needle plate. A looper is provided, the tip side is curved like a hook, and has a thread hooking portion on the inner periphery of the curved tip, and the tip thread hook is centered on an axis provided on the back side of the needle plate A movable scalpel that is reciprocally driven and swung in a horizontal plane between the looper reciprocating rocking motion path and the needle plate so that the section traverses a plurality of needle drop holes, A plurality of needle threads and loops that are hooked on the thread hook and transferred to the side of the needle drop hole A fixed knife that cuts the thread by a shearing action with the movable knife, and elastically sandwiching and guiding the swing of the movable knife between the movable knife and the fixed knife, and the cut yarn end In a sewing machine with a thread trimmer equipped with a thread clamping plate that can be elastically clamped between the tip of the movable knife and the movable knife, the blade edge of the fixed knife is movable at the elastic contact point with the movable knife. The movable knife swings between the fixed knife and the thread clamp plate over its entire reciprocating drive swing range while changing between the tip thread hook and its proximal end in response to the swing of the knife. So that the rear side of the cloth feeding direction is formed in a slanting straight line along the inclined direction gradually separating from the cloth feeding groove, and the free end edge of the thread pinching plate is The movable knife swings over the entire reciprocating drive swing range of the movable knife. In order to sandwich and guide between the fixed knife and the blade edge of the fixed knife, it is formed in a slanting linear shape along the inclined direction at substantially the same plane position as the fixed knife, and the fixed knife and the thread pinching plate are made of cloth. It is characterized by being fixed to the back surface of the needle plate so as not to protrude outward from one side of the needle plate having both sides parallel to the feed direction.

  According to the present invention having the above-described characteristic configuration, the blade edge of the fixed knife and the free end edge of the thread clamp plate that pinch and guide the swing of the movable knife are pinched by a pinch guide point by both (fixed knife and thread clamp plate). In accordance with the reciprocating drive swing of the movable knife, the rear side of the cloth feed direction is inclined along the inclination direction gradually away from the groove for the cloth feed teeth so that it changes between the front end thread hook part and the base end part. Since it is formed in a straight line, it is possible to move the movable knife without causing the proximal ends of the fixed knife and the thread pinching plate to protrude to the side part of the needle plate as in the conventional example shown in Patent Document 1. It is possible to reliably perform the pinch guide operation and the thread trimming operation of the thread, and the fixed knife and the thread pinching plate are accommodated within the width of a standard throat plate not provided with a thread trimming device and fixed to the back surface thereof. be able to. Therefore, it is not necessary to provide a mounting base for fixing the base end of the fixed knife and the thread clamp plate separately from the needle plate, so that the number of parts and assembly man-hours can be reduced, and it can be moved to a part of the cylindrical bed. There is no need to form a bulge to the side so as not to disturb the swinging movement of the knife, and the cylindrical bed can be made as small and small as possible. Even if it is a small-diameter cylindrical part of the product to be sewn, it can be easily and smoothly inserted into the cylindrical bed without being caught from its free end side, and the predetermined sewing can be performed. The applicable range can be expanded by reducing the minimum diameter of the cylindrical portion that can be sewn by the sewing machine.

  In addition, it is possible to cut a plurality of threads that are hooked on the thread hook of the movable knife and transferred to the side while moving along the long blade edge of the fixed knife. Since the thread cutting load can be distributed without concentrating the load on the location, it is possible to suppress blade edge wear (so-called blade spillage) and sharpness degradation due to deformation, and the troublesome work of frequently changing the fixed knife Even if it is not, there is an effect that it is possible to ensure a thread cutting function that is always sharp over a long period of time.

  In the sewing machine with a thread trimming device according to the present invention, the fixing attachment structure of the fixed knife and the thread pinching plate to the back surface of the needle plate is any structure as long as the attachment portion does not protrude from the side of the needle plate. In particular, as described in claim 2, the fixed knife and the thread pinching plate may be provided with a cloth feeding direction from the oblique straight blade edge and the free edge to the front in the cloth feeding direction. A mounting plate that is sufficiently long in a narrow space is formed by integrally forming parallel or substantially parallel mounting plates, and fixing the fixed knife and thread clamp plate to the back of the needle plate with a screw member. The fixing knife and the thread pinching plate can be firmly fixed to the back surface of the needle plate so as not to be damaged or deformed even when subjected to a cutting load.

  In addition, the movable knife in the sewing machine with a thread trimming device according to the present invention may have any shape in which at least the tip side is curved in a hook shape. In particular, the movable knife as described in claim 3 An outer peripheral edge that does not protrude outwardly from one side of the needle plate having both sides parallel to the cloth feeding direction when it is swung back to the maximum by the thread cutting position by the shearing action with the fixed knife. A curved shape having an inner peripheral edge located on the outer side of the groove for the cloth feed dog when the tip threading portion of the movable knife is swung as far as possible to the threading position crossing the plurality of needle drop holes What is formed in is preferable. In the movable knife having such a shape, as described above, while using a standard throat plate not provided with a thread trimming device, the movable knife is not partially protruded from the side of the throat plate. In addition to being able to be swung, the base end portion can be made as wide as possible so that it can be configured as a movable knife having high strength despite being thin.

  Furthermore, in the sewing machine with a thread trimming device according to the present invention, as described in claim 4, from the point in time when the leading thread hooking portion of the movable knife hooks a plurality of needle threads and looper threads and starts transfer. Until each thread is cut by the shearing action of the movable knife and the fixed knife, the feeding of a plurality of needle threads is restricted at a position upstream of the needle drop hole of the needle plate in the thread supply path. It is preferable to provide a needle thread presser device that prevents the cut end of the needle thread from being elastically clamped between the movable knife tip and the thread pinching plate. In this case, by restricting the feeding of a plurality of needle threads until the thread cutting with the movable knife and the fixed knife is completed, it is hooked on the thread hook of the movable knife and transferred to the side for cutting. Since the cut end of the needle thread is not clamped between the tip of the movable knife and the thread clamp plate, the end of the cut thread can be suspended as a free end, so that the sewing is completed. When pulling out the cylindrical part from the cylindrical bed, the resistance due to the elastic clamping force does not work, and the cylindrical part that has been sewn can be pulled out of the cylindrical bed easily and smoothly. Can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic perspective view of an entire three-needle cylinder type sewing machine with a thread trimming device according to the present invention, and FIG. 2 is a plan view crossing a part of the sewing machine and centering around a thread trimming device which is a main part. FIGS. 3 and 3 are enlarged longitudinal sectional views taken along line XX in FIG. This three-needle cylinder type sewing machine M has a sewing machine main shaft, a needle drive mechanism and a presser drive mechanism (they are well-known, and the detailed structure and description thereof are directed from the lower part of the sewing machine bed 2 to the front. The cylindrical bed portion 1 is extended together with a sewing machine arm portion 3 that is built in, and a needle plate 5 is fixed on the free end portion of the cylindrical bed portion 1 with screws 4. In addition, a looper 6 and a looper driving mechanism that reciprocally swings in a bc direction intersecting (orthogonal) with the cloth feeding direction (sewing progress direction) a and a looper driving mechanism (this is well-known and detailed) And the bed cover 7 surrounding the looper 6 and the looper drive mechanism is detachable from the front end side of the free end of the cylindrical bed 1. Is provided.

  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. A thread trimming device 18 having a movable knife 15, a stationary knife 16, a thread clamp plate 17 and the like, which will be described later, as main components is mounted on the back surface of the needle plate 5 that is formed.

  3 and 4 to 6 show a specific structure of the thread trimming device 18, and the movable knife 15 is curved in a hook shape on the tip side and has a hook-shaped thread hook 15a on the inner periphery of the curved tip. In addition, the base end portion 15b is fixed to the back surface of the needle plate 5 via a screw shaft 19, and the hook-shaped thread hook portion 15a at the tip centering on the screw shaft 19 has three needle drop holes 13. The retreat position shown in the phantom line of FIGS. 5 and 6 can be reciprocally swung in the horizontal direction between the looper 6 reciprocating rocking motion path and the needle plate 5 in the direction of arrow de. To the outer peripheral edge 15c that does not protrude outward from the one side 5a parallel to the cloth feed direction a of the needle plate 5 and the advanced position shown by the solid line in FIGS. When it is swung in the forward direction, it has a shape having an inner peripheral edge 15d located outside the cloth feed groove 14 of the needle plate 5. To have.

  As clearly shown in FIG. 2, an air cylinder 20 that extends and contracts in the direction of the arrow gg is attached to the outer surface of one side of the sewing machine bed portion 2, and a connecting block 22 is connected to the movable rod 21 of the air cylinder 20. A drive rod 25 that is interlocked and connected via a shaft 23 and a swing connection link 24 and reciprocally driven in the direction of the arrow fg is inserted and supported in the cylindrical bed portion 1. The movable knife 15 can be reciprocally driven in the reciprocating direction in the direction of the arrow de through the air cylinder 20 by fitting and connecting it to a pin 26 protruding near the base end 15b of the movable knife 15. It is configured.

  On the other hand, the fixed knife 16 in the thread trimming device 18 moves backward from the advance position shown by the solid line in FIGS. 5 and 6 to the retreat position shown by the phantom line in FIG. When swinging in the direction d from the arrow e, three needle threads and one looper thread that are hooked on the hook-shaped thread hook 15a at the tip and transferred to the side of the needle drop hole 13 are transferred. The thread scissor plate 17 is cut by a shearing action with the movable knife 15, and the thread pinching plate 17 is elastically pressed and contacted with the lower surface of the movable knife 15 via a spring plate 27, so that the movable knife 15 swings. It is elastically clamped and guided between the fixed knife 16 and the cut yarn end is elastically clamped between the tip of the movable knife 15.

  The fixed knife 16 having the above-described function has a blade edge 16a whose tip is in the vicinity of the thread hooking portion 15a and its base end when the elastic contact point with the movable knife 15 is reciprocally driven by the movable knife 15. The cloth feed direction a so that the swing of the movable knife 15 is sandwiched and guided between the fixed knife 16 and the thread pinching plate 17 over the entire reciprocating drive swing range while changing between the portions close to the portion 15b. The rear side of the cloth is formed in a slanting linear shape along an inclination direction gradually separating from the groove 14 for the cloth feeding teeth, and the cloth is formed from the slanting straight blade edge 16a toward the front side in the cloth feeding direction a. A mounting plate portion 16b parallel to the feed direction a is integrally formed, and the fixing knife 16 is fixed to the back surface of the needle plate 5 via the screw member 28 in the mounting plate portion 16b.

  Further, the free end edge 17 a of the thread pinching plate 17 sandwiches and guides the swing of the movable knife 15 with the fixed knife 16 over the entire reciprocating drive swing range of the movable knife 15. The position of the fixed knife 16 is substantially the same plane as the edge 16a of the fixed knife 16, specifically, as shown in FIG. A mounting plate portion 17b parallel to the cloth feeding direction a is integrally formed from the slanted straight free end edge 17a toward the front side in the cloth feeding direction a. The mounting plate portion 17b The thread pinching plate 17 includes a slanting straight free end edge 27a that elastically presses the free end edge 17a of the thread pinching plate 17 and a mounting plate portion 27b that overlaps the mounting plate portion 17b. A spring plate 27 having a substantially similar shape, and It is fixed to the back surface of the fixed knife 16 via the screw member 30 in a square shape state where the pressing plate 29 was polymerized for. A long hole 27c is formed in the mounting plate portion 27b of the spring plate 27 so that the elastic pressing position of the thread pinching plate 17 can be adjusted. A concave groove 5A is formed on the back surface of the needle plate 5 to which the fixed knife 16, the thread pinching plate 17, the spring plate 27, and the pressing plate 29 are attached.

  Further, as shown in FIG. 1, three needle threads 31 (see FIG. 1) supplied toward the three needles 11 are provided at the position of the tip of the sewing machine arm portion 3 in the three-needle cylinder type sewing machine M. Then, a needle thread presser 32 capable of restricting and releasing the supply of the feed-out shown in FIG. 8 and FIG. 9 is provided. As shown in FIGS. 8 and 9, the needle thread presser device 32 includes a needle thread presser plate mounting base 35 having one end fixed to a face plate 33 at the tip of the sewing machine arm 3 via a screw member 34, and One end of the needle thread pressing plate mounting base 35 is disposed opposite to the front portion of the needle thread pressing plate mounting base 35 via a spring 37 interposed between the head portion of the screw member 36 with the head screwed and fixed to the face plate 33. The movable needle thread pressing plate 38 elastically biased to swing toward the needle thread pressing plate mounting base 35 with the portion as a fulcrum, and the movable needle thread pressing plate 38 resists the elastic biasing force of the spring 37. And an air cylinder 39 that is driven to swing away from the needle thread pressing plate mounting base 35.

  As is apparent from the timing chart of FIG. 10, the needle thread presser 32 is attached to the needle thread presser plate as shown in FIG. 8 by the extension operation of the air cylinder 39 during normal sewing. It is driven and swung away from the table 35 to allow (unregulate) the supply of the three needle threads 31 and the air cylinder 39 contracts simultaneously with the start of the thread trimming operation by the thread trimming device 18 after the end of sewing. In accordance with the operation, the movable needle thread pressing plate 38 is swung toward the needle thread pressing plate mounting base 35 side as shown in FIG. 9 by the elastic biasing force of the spring 37, and the three needle threads 31 are moved to the movable needle thread pressing plate 38 and the needle. As shown in FIG. 8, the air cylinder 39 is again extended by the extension operation of the air cylinder 39 simultaneously with the end of the yarn trimming operation by the yarn trimming device 18 by pressing and holding between the yarn pressing plate mounting base 35 and the yarn trimming device 18. Needle thread 31 And it operates so as to release the restriction of supply.

  Next, the sewing and thread trimming actions of the three needle cylinder type sewing machine M provided with the thread trimming device 18 and the needle thread presser 32 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 the 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 trimming device 18 has the hook-shaped thread hooking portion 15a at the tip thereof traversing the three needle drop holes 13 in the needle plate 5 as shown in FIGS. The forward drive is swung to the advance position indicated by the solid line, and then the reverse drive is swung from the advance position to the retreat position indicated by the phantom line in FIGS. During the backward drive swing, the three needle threads 31 passing through the needle drop hole 13 in the vertical direction and the looper thread (not shown) locked to the looper 6 are hooked thread hooks 15a. And is transferred to one side of the needle drop hole 13 and the feed dog groove 14 and is cut by the shearing action between the movable knife 15 and the fixed knife 16, and the cut yarn end portion Is elastically sandwiched between the tip of the movable knife 15 and the free end edge 17a of the thread pinching plate 17.

  In the entire reciprocating drive swing range between the advance position and the retract position of the movable knife 15 as described above, the movable knife 15 is pinched and guided between the fixed knife 16 and the thread pinching plate 17 and swings. In this state, the rocking is performed smoothly and stably along a certain horizontal plane. Here, in the present invention, the blade edge 16a of the fixed knife 16 that guides the swing of the movable knife 15 and the free end edge 17a of the thread clamp plate 17 are pinching guide points by both (the fixed knife 16 and the thread clamp plate 17). The groove 14 for the cloth feed teeth is located toward the rear side in the cloth feed direction a so that the distance between the distal end portion including the hook-shaped thread hooking portion 15a and the base end portion changes according to the reciprocating drive swing of the movable knife 15. Since the base portion of the fixed knife 16 and the thread pinching plate 17 does not protrude from the side portion of the needle plate 5, the movable knife 15 It is possible to reliably perform the pinching guide operation and the thread trimming operation. The fixed knife 16 and the thread pinching plate 17 are provided with a thread trimming device in which both sides 5a and 5a are formed in parallel to the cloth feeding direction a. Fits within the width of the standard throat plate 5 It can be fixed to the rear surface thereof. This eliminates the need to use a special mounting base to fix the base end of the fixed knife 16 and the thread pinching plate 17 and can reduce the number of parts and the number of assembling steps. There is no need to form a side bulging portion, and the cylindrical bed portion 1 can be made as small and small as possible. As a result, the small-diameter cylindrical portion of the product to be sewn can be obtained. However, it can be easily and smoothly inserted into the cylindrical bed portion 1 without being caught from its free end side, and predetermined sewing can be performed.

  Further, the three needle threads 31 and the looper thread that are hooked on the hook-shaped thread hook 15 a of the movable knife 15 and transferred to the side are cut while moving along the long blade edge 16 a of the fixed knife 16. Since the thread cutting load can be distributed along the blade edge 16a without concentrating the cutting load on a specific portion of the blade edge 16a, the blade edge 16a is worn out (so-called blade spillage) Deterioration of sharpness due to deformation is suppressed, and a thread cutting function that is always sharp for a long period of time can be ensured without troublesome work such as frequent replacement of the fixed knife 16.

  Further, the above-described needle thread presser 32 is provided, and the leading thread hooking portion 15a of the movable knife 15 in the thread trimming apparatus 18 hooks the three needle threads 31 and the looper thread to start the transfer. By restricting the supply of the three needle threads 31 from the start time to the end time of the thread trimming operation where the cutting of the movable knife 15 and the fixed knife 16 by the shearing action is completed, the movable knife 15 is controlled. The cut end portions of the three needle threads 31 that are hooked on the yarn hooking portion 15a, transferred to the side, and cut are sandwiched between the distal end portion of the movable knife 15 and the free end edge 17a of the yarn clamping plate 17. It is possible to prevent the cutting needle thread end portion from hanging down as a free end below the needle plate 5, so that the cylindrical portion that has been sewn can be turned into the cylindrical bed portion. When pulling out from 1, elastic Not work resistance by lifting force, effortlessly tubular portion sewn completed, and can be withdrawn smoothly from the cylindrical bed 1.

  In addition, in the said embodiment, although what was applied to the three needle cylinder type sewing machine M was explained in full detail, you may apply to a two needle cylinder type sewing machine.

  Further, in the above-described embodiment, the description has been given of the one equipped with the needle thread presser device 32 in addition to the thread trimmer device 18, but even when the needle thread presser device 32 is not provided, the thread trimmer device 18 performs. The effect can be achieved.

  Further, in the above embodiment, the start timing of the needle thread presser operation by the needle thread presser device 32 is made coincident with the start timing of the thread trimmer operation by the thread trimmer device 18, and the needle thread presser operation by the needle thread presser device 32 is performed. In the above description, the end timing of the needle thread presser 32 is made to coincide with the end time of the thread trimming operation performed by the thread trimming device 18. However, as indicated by the dotted line in FIG. It is set so as to be slightly before the start timing of the thread trimming operation by the device 18, and the end timing of the needle thread presser operation by the needle thread presser device 32 is slightly less than the end timing of the thread trimming operation by the thread trimming device 18. It may be set to be later.

1 is a schematic perspective view of an entire three needle cylinder type sewing machine with a thread trimming device according to the present invention. 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. FIG. 3 is an enlarged longitudinal sectional view taken along line XX in FIG. 2. It is a disassembled perspective view of the thread trimming device in a sewing machine same as the above. It is an enlarged plan view of the yarn trimming device. It is an enlarged bottom view of the yarn trimming device. It is an expanded longitudinal cross-sectional view of the principal part of the thread trimming device. It is an enlarged plan view which shows the state at the time of normal sewing of the needle thread presser device in a sewing machine same as the above. It is an enlarged plan view showing a needle thread presser operating state by the needle thread presser. It is a timing chart of the needle thread presser.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical bed part 5 Needle plate 5a Side part 6 of a needle plate Looper 11 Needle 13 Needle drop hole 14 Feed dog groove 15 Movable knife 15a Hook-like thread hook part 15b Base end part 16 Fixed knife 16a Blade edge 16b Attachment Plate portion 17 Thread pinching plate 17a Free end edge 17b Mounting plate portion 18 Thread trimming device 19 Screw shaft 28, 30 Screw member 31 Needle thread 32 Needle thread presser device a Cloth feed direction (sewing advance direction)
M Three needle cylinder type sewing machine

Claims (4)

At the free end of the cylindrical bed, there are a plurality of needle drop holes perpendicular to the cylinder axis direction and grooves for cloth feed teeth that are arranged before and after the needle drop holes and feed the cloth in the cylinder axis direction. A needle plate is fixed, and a looper that reciprocally swings in a direction crossing the cloth feeding direction is provided in a cylindrical bed at the bottom of the needle plate, and the tip side is curved in a bowl shape. A reciprocating swinging motion of the looper having a thread hooking portion on the inner periphery of the tip and so that the tip yarn hooking portion traverses a plurality of needle drop holes around an axis provided on the back side of the needle plate A movable knife that is reciprocally driven and swung in a horizontal plane between the path and the needle plate, and when this movable knife is reciprocally swung, it is hooked on the thread hook and transferred to the side of the needle drop hole. A fixed knife that cuts a plurality of needle threads and looper threads by a shearing action with a movable knife; A thread pinch plate that contacts the knife and elastically holds and guides the swing of the movable knife between the fixed knife and elastically holds the cut thread end portion between the tip of the movable knife; In a sewing machine with a thread trimming device provided with
The fixed knife has its blade edge swinging the movable knife while the elastic contact point with the movable knife changes between the tip threading portion and the proximal end portion according to the reciprocating drive swing of the movable knife. The rear side of the cloth feed direction becomes longer and slanted linearly along the inclination direction gradually away from the cloth feed groove so as to be pinched and guided between the fixed knife and the thread clamp plate over the entire reciprocating drive swing range. Formed,
The thread clamping plate has a blade edge of the fixed knife so that its free end edge pinches and guides the swing of the movable knife between the movable knife and the fixed knife over the entire reciprocating drive swing range of the movable knife. And is formed in a slanting straight line along the inclined direction at substantially the same plane position,
In addition, the fixed knife and the thread pinching plate are fixed to the back surface of the needle plate in a state in which they do not protrude outward from one side of the needle plate having both sides parallel to the cloth feeding direction. Sewing machine with cutting device.   The fixed knife and the thread pinching plate are integrally formed with a mounting plate portion that is parallel or substantially parallel to the cloth feed direction from the oblique straight blade edge and the free end edge toward the front side in the cloth feed direction. The sewing machine with a thread trimming device according to claim 1, wherein a fixing knife and a thread pinching plate are fixed to the back surface of the needle plate via a screw member in these mounting plate portions.   When the movable knife is swung backward to the maximum by the shearing action with the fixed knife, the outer side of the needle plate having both sides parallel to the cloth feeding direction is outward. The outer peripheral edge that does not protrude and the inner peripheral edge that is located outside the groove for the cloth feed dog when the tip thread hook of the movable knife is swung as far as possible to the thread hook position that crosses the plurality of needle drop holes The sewing machine with a thread trimming device according to claim 1 or 2, wherein the sewing machine is formed in a curved shape.   From the time when the tip threading portion of the movable knife hooks a plurality of needle threads and looper threads to start transfer, until the time when cutting of each thread by the shearing action of the movable knife and the fixed knife is completed, A plurality of needle threads are held and held at a position upstream of the needle drop hole of the needle plate, and the feeding thereof is restricted, so that the needle thread end after cutting becomes the tip of the movable knife and the thread. The sewing machine with a thread trimming device according to any one of claims 1 to 3, further comprising a needle thread presser device that prevents elastic pinching between the pinch plates.

Images