JP2017046758A - sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sewing machine capable of inhibiting the disordered movement of a needle thread which comes out upward from a hook and jumps up during sewing.SOLUTION: During sewing, an outer hook 8 rotates around a hook shaft 62 as a center. A hook point 71 of the outer hook 8 captures a needle thread loop, so that the needle thread loop is gradually enlarged. After the needle thread loop has fully turned around an inner hook 9, the hook point 71 of the outer hook 8 releases the needle thread loop. The needle thread loop is spirally twisted due to expansion and contraction when turning around the inner hook 9, the twists of a needle thread, or the like. The spirally twisted needle thread loop sometimes jumps upward due to momentum in the course of coming out from the inner hook. When the needle thread loop is twisted, the needle thread loop jumps up in various directions. An upper knife 27 of a thread cutting mechanism includes a body part 112 which is wide in a left-and-right direction, so that, even when the needle thread jumps up in any direction, it can be brought into contact with the undersurface of the body part 112. As a result, a sewing machine can inhibit the jumping-up of the needle thread coming out from the inner hook 9, so that it can prevent the needle thread from getting entangled with the upper knife 27.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sewing machine.

  The sewing machine includes a rotary hook below the needle plate. The rotary hook has an inner hook and an outer hook. The inner hook houses a bobbin around which a lower thread is wound. The outer hook is provided below the needle plate and supports the inner hook inside. When sewing the fabric, the outer hook rotates about the hook shaft extending horizontally as the sewing needle moves up and down. The outer hook catches the upper thread ring formed when the sewing needle ascends from the lowest point with the sword. The upper thread ring gradually expands around the inner hook. After the upper thread ring has gone around the inner hook, the sword tip of the outer hook releases the upper thread ring. The balance picks up the upper thread ring. The upper thread ring passes upward through the needle hole of the needle plate and entangles with the lower thread, forming a stitch on the cloth.

  The upper thread ring may expand and contract when it turns around the inner hook, and may be twisted in a helical shape by twisting the upper thread. The upper thread twisted in a spiral shape jumps upward with the momentum that has come out of the inner hook. When the upper thread is twisted, the direction in which the upper thread jumps is various and unpredictable. The sewing machine has a thread trimming mechanism between the needle plate and the shuttle. The thread trimming mechanism cuts the upper thread and the lower thread with the cooperation of the fixed knife and the moving knife. The fixed knife has a cutting edge at the tip and is disposed above the hook. The upper thread ring that has come out of the inner hook springs up vigorously upward and may fly over the fixed knife and close to the needle plate. At that time, the upper thread that has been twisted is entangled with the fixed knife, and as a result, thread tightening failure at the stitches is caused. The sewing machine described in Patent Document 1 forms a ring presser and a bulge at the free end of an upper spring provided in the outer hook. The ring presser extends beyond the tip of the sword in the direction of rotation of the outer hook. The bulging portion is provided on the ring presser and bulges toward the tip of the sword.

Japan Utility Model No.2-11000

  Since the sewing machine described in Patent Document 1 has a ring presser provided in the outer hook, the gap between the outer hook sword tip and the bulge part of the ring presser is narrow, and the upper thread is caught by the bulge part so that the sword tip is raised. The yarn may not be captured. Since the bulging portion is located on the rear end side of the hook shaft with respect to the tip of the sword tip, it does not hit the upper thread that jumps up unpredictably from the rotary hook, and as a result, the sewing machine cannot suppress the poor tightening.

  An object of the present invention is to provide a sewing machine that can suppress the rampage of an upper thread that jumps upward from a hook during sewing.

  A sewing machine according to claim 1 of the present invention includes a sewing needle that holds an upper thread and moves up and down, a needle plate having a hole through which the sewing needle passes, an inner hook that houses a bobbin around which a lower thread is wound, and the needle It is provided below the plate and supports the inner hook inside, rotates around the hook shaft extending horizontally as the sewing needle moves up and down, and captures the upper thread ring formed below the needle plate with a sword tip. Cooperation between the fixed blade and a fixed blade member provided below the needle plate, having a fixed blade at a tip portion close to the hole of the needle plate and provided above the outer hook and the needle plate In the sewing machine including a movable blade member having a movable blade that cuts the upper thread and the lower thread, the fixed blade member is at least on the tip end side and the upper thread ring of the outer hook is detached from the sword tip. Above the sword tip at the time, in a plan view, in a portion where the sword tip passes inside the upper thread ring. Characterized by comprising a large wide portion of the axis parallel to the direction of width of the hook shaft that. When the sewing machine sews the cloth, the outer hook rotates around the hook shaft. Since the sword tip of the outer hook captures the upper thread ring, the upper thread ring gradually expands. After the upper thread ring has gone around the inner hook, the sword tip of the outer hook releases the upper thread ring. The upper thread ring may expand and contract when it turns around the inner hook, and may be twisted in a helical shape by twisting the upper thread. The upper thread twisted in a spiral shape may spring up with the momentum that has come out of the inner hook. When the upper thread is twisted, the upward direction of the upper thread is varied. Since the fixed blade member has the wide portion, it can be applied to the wide portion regardless of the direction in which the upper thread springs up. Therefore, it is possible to prevent the upper thread that has come out of the inner hook from violating, so that the upper thread can be prevented from being entangled with the fixed blade member. Therefore, the sewing machine can effectively prevent the thread tightening failure.

  A sewing machine according to a second aspect of the present invention is the sewing machine according to the first aspect, wherein one end portion of the wide width portion opposite to the shuttle shaft side is located at the opposite end of the wide portion. It is located on the opposite side to the shuttle shaft. One end of the wide portion is positioned on the opposite side of the hook shaft from the sword tip of the outer hook. Therefore, the sewing machine can be applied to the wide portion regardless of the direction in which the upper thread that pulls out from the inner hook vigorously jumps upward.

  A sewing machine according to a third aspect of the invention has the configuration of the invention according to the first or second aspect, and is located below the needle plate and at a position aligned with the fixed blade member in the axial direction of the shuttle shaft. A threading member provided, the threading member extending the upper thread ring that has come out of the inner hook when the upper thread and the lower thread are cut by the fixed blade and the movable blade. It is located below the movement locus of the moving blade. The sewing machine is provided so that the threading member is aligned with the fixed blade member in the axial direction of the shuttle shaft. The threading member is positioned below the movement locus of the moving blade so as to spread the upper thread ring that has come out of the inner hook. Therefore, the sewing machine can also apply the upper thread that escapes upward from the vertical shuttle to the stringing member. That is, the wide portion can share the function of suppressing the upper thread rampage with the threading member. Therefore, since it is not necessary to unnecessarily widen the wide portion of the fixed blade member, it is possible to prevent the fixed blade member from becoming too rigid and causing the cutting failure of the upper thread and the lower thread due to the fixed blade and the moving blade.

The perspective view of the sewing machine 1. FIG. The front view around the rotary hook 61. FIG. The top view of the rotary hook 61, the upper knife 27, and the stringer 29 seen from the bed part side. The figure which abbreviate | omitted the upper knife 27 and the stringer 29 from FIG. The top view of the upper knife 27, the lower knife 28, and the stringer 29 seen from the bed part side. The top view of the upper knife 27. FIG. The front view around the rotary hook 61 when the upper thread 17 comes off the sword tip 71. FIG.

  Embodiments of the present invention will be described with reference to the drawings. In the following description, left, right, front, back, and top and bottom indicated by arrows in the figure are used. A sewing machine 1 shown in FIG. 1 is, for example, a lockstitch sewing machine.

  The outline of the structure of the sewing machine 1 will be described with reference to FIGS. The sewing machine 1 includes a bed portion 2, a pedestal column portion 3, an arm portion 4, and the like. The bed portion 2 extends in the left-right direction, and includes a lower shaft 21, a shuttle mechanism 6, a thread trimming mechanism 7 (see FIG. 2, omitted in FIG. 1) and the like. The pedestal 3 extends upward from the right end side of the bed 2 and includes a timing belt 31, a sewing machine motor 32, and the like inside. The arm part 4 extends leftward from the upper side of the pedestal part 3. The arm portion 4 faces the upper surface of the bed portion 2 and includes a main shaft 41 and the like inside. The sewing machine motor 32 rotates the main shaft 41 clockwise as viewed from the left side.

  The arm portion 4 includes a tip portion 5 on the left side. The distal end portion 5 includes a needle bar vertical movement mechanism 45, a balance drive mechanism 50, a needle bar drive mechanism 10 and the like. The right end of the main shaft 41 is connected to the sewing machine motor 32, and the left end is connected to the needle bar vertical movement mechanism 45. The sewing machine motor 32 rotates the main shaft 41. The main shaft 41 transmits the rotational force of the sewing machine motor 32 to the needle bar vertical movement mechanism 45 and the balance drive mechanism 50, and drives the needle bar vertical movement mechanism 45 and the balance drive mechanism 50. The balance drive mechanism 50 includes a balance 51. The balance 51 moves up and down during sewing to pull up the upper thread. The left side of the balance drive mechanism 50 is connected to the needle bar drive mechanism 10.

  The needle bar drive mechanism 10 includes a needle bar 11, needle bar support cylinders 12 and 13, a needle bar holder 14, and the like. The needle bar support cylinders 12 and 13 are fixed to a machine frame (not shown) of the sewing machine 1, respectively. The needle bar support cylinders 12 and 13 support the upper and lower parts of the needle bar 11, respectively, and guide the movement of the needle bar 11 in the vertical direction. The needle bar holder 14 holds the needle bar 11 at a position between the needle bar support cylinder 12 and the needle bar support cylinder 13. The needle bar holder 14 is connected to the needle bar vertical movement mechanism 45 via the balance drive mechanism 50. The needle bar vertical movement mechanism 45 transmits the driving force accompanying the rotation of the main shaft 41 to the needle bar holder 14. The needle bar holder 14 is driven in conjunction with the balance 51 to move the needle bar 11 up and down. The lower end of the needle bar 11 is exposed from the lower side of the tip 5 and extends downward. The needle bar 11 has a sewing needle 15 attached to its lower end. The sewing needle 15 is synchronized with the main shaft 41 (see FIG. 1), and its lower end moves up and down along a two-dot chain line A (see FIG. 2) and penetrates a needle hole 26 provided in the needle plate 25.

  The lower shaft 21 extends in the left-right direction and includes a pulley 23 at the right end. The main shaft 41 includes a pulley 42 at a position corresponding to the position of the pulley 23 of the lower shaft 21. The pulley 42 and the pulley 23 are connected via the timing belt 31. The sewing machine motor 32 rotates the main shaft 41 and rotates the lower shaft 21 clockwise via the timing belt 31 as viewed from the left side. The lower shaft 21 includes a lower shaft gear 22 on the left side of the pulley 23. The lower shaft 21 connects a cloth feed mechanism to the left side of the lower shaft gear 22. The cloth feeding mechanism is a well-known mechanism, and feeds the cloth 19 (see FIG. 2) in conjunction with the vertical movement of the needle bar 11.

  The hook mechanism 6 includes a rotary hook 61, a hook shaft 62, and a hook stopper member 16. The shuttle shaft 62 extends substantially horizontally in the left-right direction and is disposed in parallel with the lower shaft 21. The hook shaft 62 includes a hook shaft gear 63 at the right end. The hook shaft gear 63 meshes with the lower shaft gear 22 provided on the lower shaft 21. Therefore, the shuttle shaft 62 follows the lower shaft 21 and rotates counterclockwise as viewed from the left side. The left end of the hook shaft 62 is connected to the rotary hook 61. Therefore, the rotary hook 61 rotates together with the hook shaft 62. The hook stop member 16 stops the rotation of the inner hook 9 (see FIG. 2, described later) of the rotary hook 61. The rotary hook 61 is equipped with a bobbin case 64. The bobbin case 64 accommodates a bobbin (not shown) around which the lower thread is wound.

  The bed part 2 is provided with a needle plate 25 at the top. The shuttle mechanism 6 is located below the needle plate 25. The needle bar 11 is located above the needle plate 25. When the needle bar 11 is lowered, the lower end portion of the sewing needle 15 passes through the needle hole 26 opened in the needle plate 25 and reaches the rotary hook 61 of the hook mechanism 6. The rotary hook 61 entangles the lower thread pulled out from the bobbin case 64 with the upper thread held by the sewing needle 15. The balance 51 pulls the upper thread entangled with the lower thread onto the needle plate 25 and forms a stitch on the cloth 19 (see FIG. 2). The operation of the hook mechanism 6 during sewing will be described later.

  As shown in FIG. 2, the thread trimming mechanism 7 is provided between the needle plate 25 and the shuttle mechanism 6. The thread cutting mechanism 7 includes an upper knife 27, a lower knife 28, and a threading 29. The upper knife 27 is provided in front of the needle hole 26 and is fixed to a machine frame (not shown) of the sewing machine 1 provided below the bed 2. The upper knife 27 has a blade 114 at the tip. The lower knife 28 is provided behind the needle hole 26 and faces the upper knife 27 with a gap. The lower knife 28 includes a blade portion 128 (see FIG. 5). The lower knife 28 rotates the outer periphery of the rotary hook 61 along the rotation direction C (see FIG. 2) in a state where the upper thread and the lower thread are present in the gap with the upper knife 27. The lower knife 28 overlaps the lower side of the upper knife 27, and the blade portion 114 and the blade portion 128 are cut by sandwiching the upper thread and the lower thread. The stringer 29 is provided below the upper knife 27 and on the right side so as to be parallel to the upper knife 27 in the axial direction P of the shuttle shaft 62 (see FIG. 3). The threading 29 secures a thread remaining length of an amount that prevents the upper thread from coming off the sewing needle 15 at the start of sewing by pushing and expanding the upper thread ring formed at the time of thread trimming.

  The structure of the rotary hook 61 will be specifically described with reference to FIGS. In FIG. 4, the upper knife 27 and the stringer 29 shown in FIG. 3 are omitted. As shown in FIG. 2, the rotary hook 61 is located below the needle hole 26 provided in the needle plate 25. The rotary hook 61 is, for example, a vertical rotary hook. The front surface of the rotary hook 61 is arranged toward the left side of the sewing machine 1. The rotary hook 61 includes an outer hook 8 and an inner hook 9.

  The outer hook 8 is connected to the hook shaft 62 and rotates in the rotation direction B around the hook shaft 62 in synchronization with the vertical movement of the sewing needle 15. The rotation direction B is the counterclockwise direction when viewed from the left side, and is the positive rotation direction of the outer hook 8. The outer hook 8 has a substantially bottomed cylindrical shape that opens to the front side of the rotary hook 61. As shown in FIG. 4, the outer hook 8 includes a sword tip 71 and an upper spring 75 on the outer periphery. The sword tip 71 extends along the circumferential direction of the outer periphery of the outer hook 8. The tip of the sword tip 71 has a tapered shape facing the front in the rotation direction B, that is, the downstream side in the rotation direction B, and facing the rotation direction B. The sword tip 71 includes a hooking portion 73 (see FIG. 4) at the rear end portion in the rotation direction B. The hook portion 73 has a substantially hook shape and faces the tip of the sword tip 71 with a predetermined gap. The hook portion 73 is fixed to the outer peripheral portion of the outer hook 8 with a screw 77. When the needle bar 11 is lowered, the lower end portion of the sewing needle 15 reaches the rotary hook 61. The vertical movement of the sewing needle 15 and the rotation of the outer hook 8 are both synchronized with the rotation of the main shaft 41. When the sewing needle 15 is lowered, the outer hook 8 places the sword tip 71 at a position where it does not interfere with the tip of the sewing needle 15. The upper spring 75 is fixed to the outer periphery of the sword tip 71 with a screw 78. The upper spring 75 prevents the upper thread ring captured by the sword tip 71 from coming off from the base portion 72 of the sword tip 71 to the outside. The base portion 72 is a belt-like portion where the sword tip 71 passes through the inside of the upper thread ring, and is a portion excluding the tapered tip portion and the hooking portion 73 of the sword tip 71.

  As shown in FIGS. 2 and 4, the inner hook 9 is a rotating body that fits on the inner periphery of the outer hook 8 while being rotatable independently of the outer hook 8. Like the outer hook 8, the inner hook 9 has a substantially bottomed cylindrical shape that opens to the front side of the rotary hook 61. The inner hook 9 has a flange portion 85 that substantially makes a round along the circumferential direction on the outer side wall. The outer hook 8 has a groove portion 74 that substantially makes one round in the circumferential direction on the inner side wall. When the inner hook 9 is fitted to the inner periphery of the outer hook 8, the outer hook 8 is provided with a gap through which the upper thread passes during sewing. The flange portion 85 of the inner hook 9 engages with the groove portion 74 of the outer hook 8 to prevent the inner hook 9 from coming off. When the inner hook 9 rotates with respect to the outer hook 8, the groove portion 74 guides the flange portion 85. Therefore, the inner hook 9 rotates independently of the outer hook 8 and coaxially with the outer hook 8.

  The inner hook 9 is provided with a hook stop groove 80 in a front portion facing leftward. The hook stop groove 80 extends in the radial direction of the inner hook 9. The hook retaining groove 80 includes a lower thread passage 84 (see FIG. 4). The lower thread passage 84 is formed in a groove shape that is recessed toward the downstream side in the rotation direction B. The lower thread passage 84 arranges the lower thread pulled out from the bobbin and guides it above the rotary hook 61. By lifting the balance 51, the upper thread entangles the lower thread located in the lower thread passage 84 during sewing. The upper thread is pulled up together with the lower thread through the needle hole 26 to the position of the cloth 19 disposed on the needle plate 25 to form a stitch on the cloth 19. The bobbin case 64 can be attached to and detached from the inner side of the inner hook 9. The inner hook 9 has a shaft (not shown) that protrudes from the center of the inner bottom portion to the front side. The shaft rotatably supports the bobbin in the bobbin case 64. The sewing machine 1 can pull out the lower thread from the bobbin according to the sewing.

  The shape of the hook stop member 16 will be described with reference to FIGS. The hook stop member 16 is provided on the front upper portion of the rotary hook 61. The hook stop member 16 includes a proximal end portion 161 and a distal end portion 162. The base end portion 161 is formed in a substantially rectangular plate shape extending substantially horizontally from the front to the rear of the rotary hook 61. The base end portion 161 includes a fixing hole 168 penetrating in the vertical direction at the center in the left-right direction. The fixing hole 168 is a screw (not shown) for fixing to a machine frame (not shown) of the sewing machine 1 provided below the needle plate 25. The distal end portion 162 extends further rearward from the left rear end portion of the base end portion 161 and is disposed substantially horizontally with respect to the upper part on the front side of the rotary hook 61. The width in the left-right direction of the distal end portion 162 is narrower than the width in the left-right direction of the base end portion 161. The distal end portion 162 includes a hook stop piece 163 on the right side surface. The hook stop piece 163 protrudes upward from the top surface of the tip end portion 162 and is inserted into the hook stop groove 80. The hook stop piece 163 inserted into the hook stop groove 80 prevents the inner hook 9 from rotating following the outer hook 8.

  The shape of the upper knife 27 will be described with reference to FIGS. The upper knife 27 extends substantially horizontally in the front-rear direction of the sewing machine 1 and is formed in a substantially L shape in plan view. As shown in FIG. 6, the upper knife 27 includes a fixed portion 111, a main body portion 112, and a blade portion 114. The fixing portion 111 is formed in a substantially rectangular shape extending in the front-rear direction in plan view, and includes two fixing holes 118. The two fixing holes 118 are arranged side by side in the length direction of the fixing portion 111. The front side of the two fixing holes 118 corresponds to the position of the fixing hole 168 of the hooking member 16. The screw inserted through the fixing hole 168 is fastened to the machine frame of the sewing machine 1 through the fixing hole 118. Therefore, the hook stopper 16 and the upper knife 27 can be fixed below the needle plate 25. The front end portion of the fixed portion 111 is formed in a substantially arc shape in plan view. The rear end portion of the fixing portion 111 is close to the upper portion of the front outer peripheral portion of the rotary hook 61.

  The main body 112 is bent upward from the rear end portion of the fixed portion 111 and rises toward the top of the rotary hook 61 along the outer peripheral portion of the rotary hook 61 so as to be curved in a substantially arc shape when viewed from the left side. . The main body 112 has a plate shape. The width of the main body 112 (the length in the direction parallel to the axial direction P of the hook shaft 62 (see FIG. 4)) is the width of the base 72 (see FIG. 4) of the sword tip 71 of the outer hook 8 of the rotary hook 61. It is formed wider than the width. The left end portion 112 </ b> A of the main body portion 112 bulges leftward from the left end portion of the fixed portion 111. Therefore, the left end 112 </ b> A of the main body 112 is located to the left of the sword tip 71. A right end portion 112 </ b> B of the main body portion 112 is provided with a bent portion 117 having a substantially L shape in plan view between the right end portion of the fixing portion 111. The bent portion 117 is curved so as to be concave toward the left. The bent portion 117 is disposed at a position overlapping with the distal end side of the threading 29 described later in plan view. The main body 112 includes a right extending portion 115 on the distal end side (the rear side of the sewing machine 1) of the right end portion 112B. The right extending portion 115 is formed in a substantially rectangular shape in plan view extending rightward. The blade portion 114 is provided at the distal end portion of the main body portion 112. The blade 114 is formed in a substantially rectangular shape that is long in the left-right direction in plan view. The left end portion 112 </ b> A of the main body portion 112 bulges leftward from the left end portion of the blade portion 114.

  The shape of the lower knife 28 will be specifically described with reference to FIG. The lower knife 28 includes a base 121, a catching part 122, a thread receiving groove 123, a cut groove 124, an extending part 125, a through hole 126, a raised part 127, a blade part 128, a guide part 129, and the like. The base 121 is formed in a plate shape, and is curved in a substantially arc shape along the outer peripheral portion on the rotary hook 61 side (see FIG. 2). The base 121 includes two fixing holes 145 on the right end side. The fixing hole 145 is a hole for fixing the base 121 to a holder mechanism (not shown) with a screw (not shown). The holder mechanism is a known mechanism that supports the lower knife 28 so as to be rotatable around the rotary hook 61 along the rotation direction C. The base 121 includes an extension 125 on the left side of the front end. The extending portion 125 is formed in a plate shape, has a substantially rectangular shape in plan view, and curves in a substantially arc shape toward the front. The capturing part 122 is formed in a plate shape, and is curved in a substantially arc shape from the front end part of the base part 121 toward the front so as to be adjacent to the right side of the extending part 125. The thickness of the capture part 122 is thinner than the thickness of the base part 121. The front end portion of the capturing unit 122 is inclined so that the right end side is behind the left end side in plan view. The angle formed by the front end portion and the left end portion of the capturing portion 122 is an acute angle. The capturing unit 122 includes an end surface 141 on the left side of the front end. The end surface 141 is formed in a tapered shape that is inclined obliquely downward with respect to the upper surface of the capturing portion 122.

  The cut groove 124 is provided between the extending portion 125 and the capturing portion 122 and is formed by cutting backward in a substantially V shape in plan view. The yarn receiving groove 123 linearly extends rearward from the rearmost portion of the cut groove 124 to the vicinity of the rear end portion of the left end portion of the catching portion 122. The through hole 126 is provided at the rear end of the yarn receiving groove 123. The through hole 126 penetrates the upper surface and the lower surface of the base 121 and is inclined obliquely rearward from above to below. The raised portion 127 is provided so as to rise upward along a portion of the outer peripheral edge of the through hole 126 excluding the yarn receiving groove 123. The blade portion 128 is formed by the rear upper surface of the inner peripheral surface of the through hole 126 and the upper surface of the raised portion 127. The guide portion 129 extends in a substantially arc shape from the right side of the front end portion of the base portion 121 toward the front, and protrudes forward from the front end portion of the capturing portion 122.

  With reference to FIGS. 2 and 3, the position and shape of the threading 29 will be specifically described. FIG. 3 shows the threading 29 by a two-dot chain line. The stringer 29 is provided below the upper knife 27 and adjacent to the right side of the upper knife 27 in a plan view. The stringer 29 is located below the movement locus of the lower knife 28. The stringer 29 extends substantially horizontally in the front-rear direction of the sewing machine 1 and is formed in a substantially inverted L shape in plan view. The stringer 29 includes a fixed part 131 and a stringer 132. The fixing portion 131 is formed in a substantially rectangular shape extending in the front-rear direction in plan view. The fixing part 131 includes a fixing hole 133. The fixing hole 133 is a screw (not shown) for fixing the fixing portion 131 to the machine frame of the sewing machine 1 provided below the needle plate 25. The fixing portion 131 is disposed on the right side of the fixing portion 111 of the upper knife 27 in plan view. The rear end portion of the fixing portion 131 is close to the upper portion of the front outer peripheral portion of the rotary hook 61 below the upper knife 27. The stringing portion 132 bends from the rear end portion of the fixing portion 131 diagonally to the left in the plan view, bends upward, rises, and further toward the top of the rotary hook 61 along the outer peripheral portion of the rotary hook 61. Curved and extended in an arc. The distal end portion of the stringing portion 132 has a tapered shape in plan view, and is disposed so as to overlap below the main body portion 112 of the upper knife 27.

  With reference to FIG. 5, the thread trimming operation by the thread trimming mechanism 7 will be described. The lower knife 28 moves in the rotational direction C in accordance with the thread trimming operation instruction during sewing. The lower knife 28 approaches the upper knife 27. The end surface 141 of the catching portion 122 of the lower knife 28 enters the upper thread ring of the upper thread 17 formed by the operation of the hook mechanism 6 described later, and separates the upper thread 17 and the lower thread 18 into yarns. The threading part 132 of the threading 29 enters the upper thread ring of the upper thread 17 in cooperation with the operation of the catching part 122 of the lower knife 28 and gradually widens the upper thread ring. When the catching part 122 of the lower knife 28 spreads the upper thread ring of the upper thread 17, a thread loosening mechanism (not shown) works simultaneously so that an excessive force is not applied to the upper thread 17. Therefore, the feeding of the upper thread 17 from the yarn spool (not shown) becomes gentle. When the catching portion 122 spreads the upper thread ring of the upper thread 17, one of the upper thread rings of the upper thread 17 and the lower thread 18 are positioned on the cut groove 124 side. When the upper knife 27 and the lower knife 28 approach each other, the balance 51 pulls up the upper thread 17. The upper thread 17 is wound around the lower knife 28. The lower knife 28 holds the upper thread 17 in a fixed position.

  The lower surface of the right extending portion 115 of the upper knife 27 comes into contact with and slides on the upper surface of the guide portion 129 of the lower knife 28. The lower knife 28 overlaps the lower side of the upper knife 27. The blade portion 114 of the upper knife 27 moves rearward along the yarn receiving groove 123 from the cut groove 124 of the lower knife 28. The upper thread 17 and the lower thread 18 positioned on the cut groove 124 side are disposed along the thread receiving groove 123 and are sandwiched between the upper surface of the extension portion 125 of the lower knife 28 and the lower surface of the upper knife 27. To do. The upper thread 17 and the lower thread 18 reach the through hole 126. Immediately below the needle hole 26 (see FIG. 2), the blade portion 128 of the lower knife 28 and the blade portion 114 of the upper knife 27 cooperate to sandwich and cut the upper thread 17 and the lower thread 18. At this time, the balance 51 reaches the uppermost position. The amount of the upper thread 17 and the lower thread 18 secured at the end surface 141 of the lower knife 28 is the remainder of the upper thread 17 on the sewing needle 15 side after thread trimming and the remainder of the lower thread 18 on the bobbin case 64 side. The remaining length of the upper thread 17 is the length secured by the threading 29. Therefore, the sewing machine 1 can secure a thread remaining length of an amount that prevents the upper thread 17 from coming off the sewing needle 15 at the start of the next sewing.

  With reference to FIG. 1 to FIG. 4 and FIG. 7, the function of preventing the upper thread 27 from jumping up when the shuttle mechanism 6 is being sewn will be described. 1 to 4 omit the upper thread and the lower thread. As shown in FIG. 1, the sewing needle 15 moves up and down following the rotation of the main shaft 41. The main shaft 41 is driven by being directly connected to the sewing machine motor 32. The shuttle shaft 62 is driven in synchronization with the main shaft 41 via the lower shaft 21. The outer hook 8 of the rotary hook 61 rotates following the hook shaft 62.

  When the sewing needle 15 moves downward, the sewing needle 15 penetrates the cloth 19 and enters the rotary hook 61 through the needle hole 26 of the needle plate 25. The lower end portion of the sewing needle 15 reaches a hole 89 (see FIGS. 3 and 4) on the back side (right side) of the hook stop groove 80 of the inner hook 9. The sewing needle 15 holds the upper thread passed through the needle hole 26 and carries it to the back side of the hook retaining groove 80. When the sewing needle 15 moves upward, the upper thread hardly moves upward together with the sewing needle 15 due to frictional resistance with the cloth 19. Therefore, the upper thread loosens and forms a ring (hereinafter referred to as an upper thread ring). As the outer hook 8 rotates, the sword tip 71 of the outer hook 8 captures the upper thread ring. When the outer hook 8 further rotates, the upper thread ring captured by the sword tip 71 moves along a guide groove (not shown) on the outer periphery of the outer hook 8, and the clearance between the outer hook 8 and the inner hook 9 and the rotary hook 61. Pass the front side. The end of the lower thread pulled out from the bobbin case 64 is disposed in the lower thread passage 84 (see FIG. 3).

  The upper thread ring gradually expands while turning around the inner hook 9 and surrounds the outer periphery of the lower thread located in the hook retaining groove 80. The outer hook 8 rotates in a state where the upper thread ring is maintained by the upper spring 75 so as not to be detached from the sword tip 71. As shown in FIG. 7, the upper thread ring is detached from the sword tip 71 and finally hooked on the hooking portion 73 (see FIG. 3), and comes off from the hooking portion 73 when the bobbin case 64 is completely turned. The upper thread ring detached from the sword tip 71 jumps up to the front side of the needle hole 26 below the needle plate 25 by lifting the balance 51.

  While the sword tip 71 captures and gradually expands the upper thread ring, the upper thread ring causes friction of the sword point 71 of the rotating outer hook 8, expansion and contraction when turning around the inner hook 9, and twisting of the upper thread. For example, it may be twisted spirally. The upper thread ring twisted in a spiral shape jumps up vigorously while making an irregular movement so as to be violated when it comes off the sword tip 71. Therefore, the direction in which the upper thread jumps up is unpredictable in front of the needle hole 26.

  In the present embodiment, the main body portion 112 of the upper knife 27 is disposed below the needle plate 25 and in front of the needle hole 26 and above the sword tip 71 when the upper thread ring is detached from the sword tip 71. As described above, the width of the main body portion 112 is wider than the width of the base portion 72 of the sword tip 71. Therefore, the upper thread ring that has jumped up vigorously contacts the lower surface of the main body 112 of the upper knife 27 (see FIG. 7). That is, the upper knife 27 can prevent the upper thread ring from jumping up. Further, since the left end portion 112A of the main body portion 112 is located to the left of the sword tip 71, the lower surface of the main body portion 112 no matter which direction the upper thread that pulls upward from the inner hook 9 of the rotary hook 61 jumps up in any direction. Can be reliably contacted. Therefore, the momentum of the upper thread ring disappears. The balance 51 pulls up the upper thread that has lost its momentum. The upper thread entangles the lower thread located in the lower thread passage 84. The upper thread is pulled up to the position of the cloth 19 arranged on the needle plate 25 through the needle hole 26 to form a stitch. In the present embodiment, since the upper thread ring that springs up from the rotary hook 61 does not entangle with the upper knife 27, the sewing machine 1 can prevent the upper thread from being tightly tightened.

  With reference to FIG. 3, a description will be given of maintaining the flexibility of the upper knife 27 due to the combined use of the threading 29 with respect to the function of suppressing the jumping of the upper thread. As described above, since the upper thread ring springs up irregularly in a helically twisted state, the sewing machine 1 has a wider width of the main body portion 112 in order to reliably contact the lower surface of the main body portion 112 of the upper knife 27. May be. However, if the width of the main body 112 is too wide, the rigidity of the upper knife 27 becomes stronger than necessary. If the rigidity of the upper knife 27 becomes too strong, the upper knife 27 does not bend properly when in contact with the lower knife 28, which may cause a yarn cutting failure. A moderate deflection of the upper knife 27 is necessary for a good thread trimming operation. In the sewing machine 1 of the present embodiment, the threading 29 is provided next to the right side of the upper knife 27, so that the area below the needle plate 25 and in front of the needle hole 26 is widely covered with the upper knife 27 and the threading 29. be able to. Since the rigidity of the upper knife 27 does not become excessively strong, it is possible to prevent the upper thread from bouncing up widely while enabling the thread cutting mechanism 7 to perform a good thread cutting operation.

  Further, the upper knife 27 of the present embodiment is provided with an L-shaped bent portion 117 at a portion overlapping the stringing portion 132 of the stringing 29. In the portion where the bent portion 117 is provided, the width of the main body portion 112 can be reduced. Therefore, since the sewing machine 1 can suppress the upper thread from bouncing up widely while maintaining appropriate flexibility of the upper knife 27, it is possible to achieve both good thread trimming operation and prevention of thread tightening failure.

  Further, in the present embodiment, the width of the blade portion 114 provided at the distal end portion of the main body 112 can be increased by increasing the width of the main body 112 of the upper knife 27. Therefore, even if the positional relationship between the upper knife 27 and the lower knife 28 is shifted in the left-right direction due to the dimensional tolerances of the parts, the blade portion 114 of the upper knife 27 is surely relative to the blade portion 128 of the lower knife 28. Because of the contact, the upper thread 17 and the lower thread 18 can be cut reliably.

  In the above description, the upper knife 27 corresponds to the fixed blade member of the present invention, and the blade portion 114 corresponds to the fixed blade of the present invention. The lower knife 28 corresponds to the moving blade member of the present invention, and the blade portion 128 corresponds to the moving blade of the present invention. The main body 112 of the upper knife 27 corresponds to the wide portion of the present invention, and the stringer 29 corresponds to the stringer member of the present invention.

  As described above, the sewing machine 1 of the present embodiment includes the shuttle mechanism 6 below the needle plate 25. The rotary hook 61 of the hook mechanism 6 includes an outer hook 8 and an inner hook 9. The inner hook 9 accommodates a bobbin around which a lower thread is wound. The outer hook 8 supports the inner hook 9 on the inside, rotates around the hook shaft 62 as the sewing needle 15 moves up and down, and catches the upper thread ring formed below the needle plate 25 with the sword 71 and lower thread. Tangle with. The sewing machine 1 includes a thread trimming mechanism 7 between the needle plate 25 and the rotary hook 61. The thread trimming mechanism 7 includes an upper knife 27 and a lower knife 28. The upper knife 27 is provided below the needle plate 25, and has a blade portion 114 at a tip portion above the outer hook 8 and close to the needle hole 26 of the needle plate 25. The lower knife 28 has a blade 128 that cuts the upper thread and the lower thread in cooperation with the blade 114 of the upper knife 27. The upper knife 27 includes a main body 112 on the distal end portion side that is wider than the width in the direction parallel to the axial direction P of the hook shaft 62 in the base portion 72 of the sword tip 71 of the outer hook 8 in a plan view.

  When the sewing machine 1 sews the cloth 19, the outer hook 8 rotates around the hook shaft 62. Since the sword tip 71 of the outer hook 8 captures the upper thread ring, the upper thread ring gradually expands. After the upper thread ring has gone around the inner hook 9, the sword tip 71 of the outer hook 8 releases the upper thread ring. The upper thread ring may be helically twisted due to expansion and contraction when the inner hook 9 is rotated and twisting of the upper thread. The upper thread that is twisted in a spiral shape may spring up with the momentum that has come out of the inner hook 9. When the upper thread is twisted, the upward direction of the upper thread is varied. Since the upper knife 27 includes the wide main body 112, the upper thread can be brought into contact with the main body 112 in any direction. Therefore, since the sewing machine 1 can suppress the upper thread that has come out of the inner hook 9 from jumping up, the upper thread can be prevented from being entangled with the upper knife 27. Therefore, the sewing machine 1 can effectively prevent the thread tightening failure in the cloth 19.

  The present invention can be variously modified in addition to the above embodiment. The sewing machine 1 of the above embodiment is, for example, a lockstitch sewing machine, but the present invention can also be applied to other types of sewing machines, for example, a tacking sewing machine, a staggered sewing machine, a hole sewing machine, a button sewing machine, and the like. .

  In the present embodiment, the wide body part 112 is provided on the distal end side of the upper knife 27, but the length of the body part 112 may be further extended forward, for example. Further, in the present embodiment, the position of the bent portion 117 provided at the right end portion 112B of the main body portion 112 may be changed or the bent portion 117 may be omitted according to the positional relationship with the stringer 29. In that case, the right end portion 112B of the main body portion 112 and the right end portion of the fixing portion 111 may be substantially on the same straight line. The right extension 115 provided at the right end 112B of the main body 112 may be omitted.

  In the above embodiment, the stringer 29 may be omitted. When the threading 29 is omitted, the sewing machine 1 may increase the width of the main body 112 of the upper knife 27.

DESCRIPTION OF SYMBOLS 1 Sewing machine 6 Hook mechanism 8 Outer hook 9 Inner hook 15 Sewing needle 17 Upper thread 18 Lower thread 25 Needle plate 26 Needle hole 27 Upper knife 28 Lower knife 29 Threading 41 Main shaft 62 Hook shaft 71 Blade point 112 Main body 112A Left end 114 Blade Part 128 blade part

Claims (3)

A needle that holds the needle thread and moves up and down;
A needle plate having a hole through which the sewing needle passes;
An inner hook that houses a bobbin around which a lower thread is wound;
Provided below the needle plate and supporting the inner hook inside, rotating around the hook shaft extending horizontally as the sewing needle moves up and down, and catching the upper thread ring formed below the needle plate with the sword tip And an outer hook entangled with the lower thread,
A fixed blade member provided below the needle plate, having a fixed blade at a tip portion above the outer hook and close to the hole of the needle plate;
In a sewing machine comprising a moving blade member having a moving blade for cutting the upper thread and the lower thread in cooperation with the fixed blade,
The fixed blade member is
The axis of the shuttle shaft at a portion where the tip of the blade passes through the inside of the upper thread ring in plan view, at least on the tip side and above the tip of the outer hook when the upper thread ring of the outer hook is detached from the blade tip A sewing machine comprising a wide portion wider than a width in a direction parallel to the direction. The one end part located in the opposite side to the shuttle shaft side among the both ends of the width direction of the wide part is located in the opposite side to the shuttle shaft rather than the sword tip. sewing machine. A threading member provided below the needle plate and at a position aligned with the fixed blade member in the axial direction of the shuttle shaft,
The threading member is located below the movement locus of the moving blade so as to spread the upper thread ring that has come out of the inner hook when cutting the upper thread and the lower thread by the fixed blade and the moving blade. The sewing machine according to claim 1 or 2, wherein the sewing machine is located.

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