JP4822193B2 - Box bed double chain stitch machine - Google Patents

Description

  The present invention relates to a double chain stitch sewing machine including a box-shaped bed having a flat upper surface for placing a sewing fabric on both sides of a needle plate that holds the sewing fabric between the presser foot and the presser foot.

  One type of industrial sewing machine is a box bed double chain stitch machine. The sewing machine includes a box-shaped bed having flat upper surfaces on both sides of a needle plate. The flat upper surface of the bed stably supports the sewing fabric on both sides of the needle plate, and reduces the labor for the operator to support the fabric being sewn. Therefore, the box bed double chain stitch sewing machine can be conveniently used for sewing large-sized sewing fabrics. Some box bed double chain stitch machines have a cylindrical shape with a flat upper surface at the tip side of the needle plate. This type of sewing machine is a medium cylinder type box bed double chain stitch. It is called a sewing machine.

  As another type of industrial sewing machine, there is a feeding arm type flat stitch sewing machine. This sewing machine has a narrow cylindrical sewing bed extending in one direction at the lower part of the sewing machine frame, and a sewing arm extending in a different direction from the sewing machine bed at the upper part of the sewing machine frame. The delivery arm-shaped flat stitch sewing machine is used, for example, for the stitching of the crotch part of briefs and shorts. The stitching is performed by overlapping the edges of the two fabrics to be sewn up and down over a predetermined width and feeding them between the needle plate on the sewing machine bed and the presser foot lowered on the needle plate.

  The feeding arm-shaped flat stitch sewing machine includes a special presser foot equipped with a knife mechanism (see, for example, Patent Document 1). This presser foot has a presser foot main body and two presser feet. The presser body holds the sewing fabric with the needle plate. The two presser feet extend parallel to each other in front of the presser body. The knife mechanism includes a fixed knife fixed to one presser foot and a movable knife attached to the other presser foot. The fixed knife and the movable knife are opposed to each other in front of the needle drop position (position where the needle is lowered) set in the presser body.

  The movable knife is configured to reciprocate by transmission from a knife swinging shaft inside the sewing machine arm and to slidably contact the fixed knife. The movable knife is attached so as to partially protrude outside the presser foot, and the transmission mechanism from the knife swinging shaft is connected to the protruding part of the movable knife.

  The sewing fabric is fed between two presser feet with the edges on the sewing side aligned with each other and standing on the needle plate. The edge of the sewing fabric reaches the sliding contact position of the fixed knife and the movable knife and is trimmed. The presser body is fed to the needle entry position with the edges of the trimmed fabrics stacked one above the other. In this sewing machine, it is not necessary to adjust the overlap width by an operator's manual operation, and it is possible to stably carry out the stitching having a substantially constant sewing width.

Japanese Patent Publication No. 7-57272

  The above-described stitching is also performed in a box-type bed double chain stitch machine. In a box-type bed double chain stitch machine, as described above, since the sewing fabric is stably supported on the bed, conventionally, the overlap width is manually set by the operator at the front position of the needle plate. As a result, the stitching is carried out by adjusting the sewing machine, and there is a problem that the finished state varies depending on the skill of the operator.

  This problem can be solved by applying the presser foot with the knife mechanism that the feed arm flat stitch sewing machine has, but the bed of the box-type double-ring stitch machine has a large sewing fabric as described above. For the purpose of support, it has a flat upper surface that extends on both sides of the needle plate. In addition, the presser foot with a knife mechanism provided in the feed arm flat stitch sewing machine has a movable knife projecting to one side of the presser foot as described above, and the transmission mechanism is connected to this projecting portion. When this presser foot is applied to a box-type bed double chain stitch sewing machine, the transmission mechanism of the movable knife operates near the upper surface of the box-type bed.

  On the other hand, an operator who is performing a sewing operation generally assists the feeding of the sewing fabric by pressing the sewing fabric by hand near both sides of the presser foot and pressing it in the feeding direction. Such feeding assistance is particularly important in the sewing work of large sewing fabrics handled in a box bed double chain stitch sewing machine.

  However, when a presser foot with a knife mechanism is applied to a box bed double chain stitch sewing machine, the transmission mechanism of the movable knife operates on one side of the presser foot, and on the other side of the presser foot, Since a part of the fixed knife protrudes, it is difficult to carry out the above-described feeding assistance, and there is a possibility that the sewing work may be hindered.

  On the other hand, the operator can send out a large sewing fabric and sew it together using an arm-shaped flat stitch sewing machine. However, the feeding arm type flat stitch sewing machine has a small cylindrical bed, and when trying to carry out stitching of a large sewing fabric, the support of the sewing fabric by the cylindrical bed is insufficient. The operator is forced to support the entire sewing fabric, and it is difficult to perform the sewing work well.

  The present invention has been made in view of such circumstances, and is provided with a presser foot with a knife mechanism for trimming the edges of the sewing fabric, so that the stitching can be performed with a good finish regardless of the skill level of the operator. It is another object of the present invention to provide a box bed double chain stitch sewing machine that does not hinder the feeding assist work performed by the operator on both sides of the presser foot.

A box-shaped bed double chain stitch sewing machine according to a first aspect of the present invention includes a box-shaped bed having a flat upper surface for placing a sewing fabric on both sides in the width direction of a needle plate, and an upper portion of the bed. A needle bar and a presser bar supported by the sewing machine arm; a needle and a presser foot respectively attached to the lower ends of the needle bar and the presser bar; a feed mechanism and a looper provided in the bed below the needle plate; The needle that descends together with the presser bar is pressed onto the needle plate, and the needle that moves up and down together with the needle bar, the sewing fabric to which the feed mechanism applies the feed in the longitudinal direction of the needle plate, In a box bed double chain stitch sewing machine that is sewn by the looper that swings along the lower surface of the needle plate around a support shaft parallel to the feed direction, the presser foot is placed on the upper surface of the needle plate. Reciprocate along the direction crossing the feed direction Comprising a knife mechanism having a sliding contact with the fixed knife in moving knife and movable knife, the upper surface of the bed, in one side or both sides of the needle plate, characterized Citea Rukoto lower than the upper surface of the needle plate And

The box-type bed double chain stitch sewing machine according to the second aspect of the present invention is the step provided between the upper surface of the bed and the upper surface of the needle plate so as to avoid interference with the swinging area of the looper on both sides of the needle plate. It is characterized by being continuous by the part.

Further, the box bed double chain stitch sewing machine according to the third aspect of the present invention transmits the knife swinging shaft provided inside the sewing machine arm and the repetitive rotation of the knife swinging shaft to the movable knife, and the movable knife is moved back and forth. And a transmission mechanism.

The fourth box-shaped bed double chain stitch sewing machine according to the invention, the transmission mechanism in the third invention, Yes supported through the lower portion of the sewing machine arm in the vertical direction, the support for supporting the lower portion of the presser bar The transmission that includes a transmission cylinder that fits and holds a bush, and a transmission link that transmits repetitive rotation of the female swing shaft to the upper part of the transmission cylinder that is located inside the sewing machine arm, and that protrudes outside the sewing machine arm. A mounting portion for the movable knife is provided at a lower portion of the tube.

In the box bed double chain stitch sewing machine according to the first aspect of the present invention, the presser foot that holds the sewing fabric on the needle plate is provided with a knife mechanism having a fixed knife and a movable knife , and further has a box shape. the upper surface of the bed, in one side or both sides of the needle plate and lower than the upper surface of the needle plate, to ensure a gap between the protruding portion of the movable knife to the upper surface and the outer presser foot bed treasure, worker In this gap, a hand is attached to the sewing fabric within the gap to assist the feeding, and it becomes possible to carry out the stitching of the large sewing fabric with good quality without requiring skill .

In the box bed double chain stitch sewing machine according to the second aspect of the invention, the step portion provided between the upper surface of the needle plate and the upper surface of the box bed avoiding the swinging area of the looper swinging in the box bed. Therefore, the large-sized sewing fabric can be stably supported and stitched together.

In the box bed double chain stitch sewing machine according to the third aspect of the invention, since the repetitive rotation of the female swing shaft inside the sewing machine arm is transmitted to the movable knife through the transmission mechanism, the movable knife provided on the presser foot is surely Thus, the edge of the sewing fabric is trimmed and the stitching can be performed satisfactorily.

Further, in the box bed double chain stitch sewing machine according to the fourth aspect of the invention, the transmission mechanism for transmitting the repetitive rotation of the knife swinging shaft to the movable knife is provided with a transmission cylinder that also serves as a support member for the presser bar. The present invention has an excellent effect such that transmission from the swing shaft to the movable knife outside the sewing machine arm can be realized with a simple configuration.

It is an external appearance perspective view which shows the whole structure of the box-shaped bed double chain stitch sewing machine which concerns on this invention. It is explanatory drawing of the attachment state of a needle plate. It is front sectional drawing of the sewing machine bed in the attachment position vicinity of a needle plate. It is a perspective view of the drive mechanism to a movable knife. It is an external appearance perspective view which shows other embodiment of the box-shaped bed double chain stitch sewing machine which concerns on this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is an external perspective view showing the overall configuration of a box-shaped bed double chain stitch sewing machine according to the present invention. In the following description, the upper and lower sides and the left and right sides in FIG. 1 are used as they are, and the front side of the paper in FIG.

  As shown in FIG. 1, the box-shaped bed double chain stitch sewing machine includes a box-shaped sewing bed 1, a pedestal 2, and a sewing machine arm 3. The pedestal 2 is provided on the upper surface of the right end of the sewing machine bed 1 so as to rise substantially perpendicular to the upper surface. The sewing machine arm 3 is connected to the upper end of the pedestal 2 and extends to the left in parallel with the sewing machine bed 1. A needle bar 30 and a presser bar 31 are supported at the tip of the sewing machine arm 3.

  The needle bar 30 moves up and down by the operation of a needle bar drive mechanism (not shown) provided inside the sewing machine arm 3. The needle bar 30 protrudes below the sewing machine arm 3, and a plurality of needles 4, 4... Are attached to the lower end portion of the needle bar 30 via a needle stopper 40. These needles 4, 4... Rise and fall according to the vertical movement of the needle bar 30.

  The presser bar 31 protrudes below the sewing machine arm 3 on the rear side of the needle bar 30. A presser foot 5 configured as described later is attached to the protruding end portion of the presser bar 31. The presser bar 31 is supported inside the sewing machine arm 3 so as to be movable in the vertical direction. The presser bar 31 is moved in the vertical direction by an appropriate operation of the operator, and the presser foot 5 is raised and lowered in accordance with the vertical movement of the presser bar 31.

  A needle plate 10 is attached to the upper surface of the sewing machine bed 1 so as to correspond to the lowered positions of the needles 4, 4. FIG. 2 is an explanatory diagram of a state in which the needle plate 10 is attached. As shown in the figure, the needle plate 10 is a rectangular flat plate that is long in the front-rear direction. It is attached freely. A rectangular notch 12 is formed at the front edge of the needle plate 10 in the center in the width direction (left-right direction).

  The needle plate mounting base 11 is provided with a recess 12a wider than the notch 12 at a position aligned with the notch 12 when the needle plate 10 is attached. A mounting piece 14 is engaged. The guide mounting piece 14 is pressed upward by a pressing screw 15 screwed into the screw hole on the bottom surface of the recess 12a and pressed against the back surface of the needle plate 10, and is fixed below the notch 12. The guide mounting piece 14 has two screw holes arranged in the front and rear directions. The dough guide 16 is fastened and fixed to the guide mounting piece 14 by set screws 17 and 17 screwed into the screw holes, respectively. Yes. The dough guide 16 is a flat plate-like member that extends rearward from a fixed position by the set screws 17 and 17 and is arranged so as to rise vertically to the upper surface at the center of the upper surface of the needle plate 10 in the width direction.

  Further, the needle plate 10 is formed with feed dog holes 13, 13. The feed dog holes 13, 13... Are narrow rectangular openings that are long in the front-rear direction, and are distributed in two on the left and right sides. The feed dog holes 13, 13... Are provided for projecting feed dogs operating inside the sewing machine bed 1. The feed dog is a known feed element that performs an oval motion that combines a back-and-forth motion and a vertical motion by the operation of a feed mechanism inside the sewing machine bed 1. When the feed dog moves upward, the feed dog protrudes through the feed dog holes 13, 13... And moves rearward and then moves backward, and then moves downward and returns to the front. By this operation, intermittent feed is applied to the sewing fabric (not shown) on the needle plate 10 backward.

  2, the presser foot 5 and the needles 4, 4,. When the presser foot 5 is lowered due to the downward movement of the presser bar 31, the presser foot 5 is overlapped on the needle plate 10 as shown in the figure, and holds the sewing fabric between the presser plate 10. The presser foot 5 has a presser body 50 fixed to the lower end of the presser bar 31 and two presser feet 51 and 52. The presser feet 51 and 52 are connected to the left and right sides of the presser body 50 and extend parallel to each other toward the front. The presser feet 51 and 52 are opposed to each other with an appropriate gap on the front side of the presser body 50, and form a diameter of an introduction path for the sewing fabric.

  These presser feet 51 and 52 are equipped with a knife mechanism including a fixed knife 6a and a movable knife 6b. The fixed knife 6a is a plate-shaped knife fixed to the left presser foot 51. The fixed knife 6a is inserted and fixed in a rectangular holding hole 53 provided in the presser foot 51. In FIG. 2, the base portion of the fixed knife 6 a that protrudes outside the presser foot 51 is shown. The fixed knife 6a has a blade at the tip that protrudes into the introduction path between the presser feet 51 and 52.

Movable knife 6b is inserted and held in the holding hole 54 provided on the right side of the presser foot 52. The movable knife 6b is movable in the left-right direction under the guidance of the holding hole 54. The movable knife 6b has a blade at the tip that projects into the introduction path between the presser feet 51 and 52. The base of the movable knife 6b protrudes to the outside of the presser foot 52 and is fixed to the knife holder 75 at the lower end of the mounting base 74. The mount 74 and the female holder 75 constitute a part of the transmission mechanism 7 to be described later. The movable knife 6b reciprocates in the left-right direction in response to repeated rotation of the knife swing shaft 9 (see FIG. 4 ) transmitted through the transmission mechanism 7. The reciprocating movable knife 6b is in sliding contact with the blade of the fixed knife 6a in the introduction path.

  The needles 4, 4,... Descend to the rear side of the left and right presser feet 51, 52, and the needle holes provided in the presser body 50 and the needle holes 10a, 10a provided in the needle plate 10 (see FIG. 3). The inside of the sewing machine bed 1 is reached through. In the introduction path between the presser feet 51 and 52, two sewing fabrics are introduced in a posture in which the edges are aligned and rise vertically on the needle plate 10. The fixed knife 6a and the movable knife 6b cut and align the edges of the sewing fabric that has reached the sliding contact position. The cut and aligned fabrics are vertically overlapped by the action of the presser main body 50, sent to the lowered position of the needles 4, 4,.

  The cloth guide 16 described above reaches the inside of the introduction path between the presser feet 51 and 52, and functions to maintain the rising posture of the sewing cloth in the introduction path. The position of the dough guide 16 can be adjusted together with the guide mounting piece 14 by loosening the push screw 15. By adjusting the position of the fabric guide 16, the operator can adjust the introduction posture of the sewing fabric, and can perform the trimming with the fixed knife 6a and the movable knife 6b satisfactorily. The dough guide 16 can be removed together with the guide mounting piece 14 to the front of the sewing machine bed 1 by loosening the push screw 15. The fabric guide 16 is removed when performing other stitching. The other stitching is, for example, the stitching of one of two fabrics only by cutting the edge of one fabric with the fixed knife 6a and the movable knife 6b and stitching on the other fabric (one piece of stitching) Etc.).

  A guide plate 55 is attached to the upper surface of the right presser foot 52. The guide plate 55 is a curved plate that is vertically attached to the front part of the right presser foot 52 and attached to the left presser foot 53 so as to extend obliquely toward the rear part. The guide plate 55 guides the cut piece of the sewing fabric removed by aligning the fixed knife 6a and the movable knife 6b and discharges it to the outside of the left presser foot 53.

  As shown in FIG. 1, a suction pipe 56 is attached to the lower part of the left end surface of the sewing machine arm 3 via a mounting bracket 57. The suction pipe 56 is provided with a suction opening that opens toward the left rear portion of the presser foot 5, and a cut piece discharged by the action of the guide plate 55 is sucked into the suction opening and removed. The mounting bracket 57 of the suction pipe 56 can be opened around a vertical hinge pin 58 provided at the rear. The suction pipe 56 moves to a standby position away from the presser foot 5 by opening the mounting bracket 57. The suction pipe 56 that has moved to the standby position does not hinder attachment / detachment of the sewing fabric onto the sewing machine bed 1.

  As shown in FIG. 1, the sewing machine bed 1 has flat upper surfaces 20 on the left and right sides of the needle plate 10. In the present invention, the upper surface 20 of the sewing machine bed 1 is set lower than the upper surface of the needle plate 10. On the right side of the attachment position of the needle plate 10, there is provided a step portion 21 that is obliquely cut off as it is away from the needle plate 10. Further, as shown in FIG. 2, the needle plate 10 includes tapered chamfered portions 18 and 18 on both side edges in the width direction. The chamfered portion 18 on the right edge is continuous with the stepped portion 21 when attached to the sewing machine bed 1. The upper surface 20 of the sewing machine bed 1 is continuous with the upper surface of the needle plate 10 by the chamfered portion 18 and the stepped portion 21 or the chamfered portion 18.

  FIG. 3 is a front sectional view of the sewing machine bed 1 in the vicinity of the attachment position of the needle plate 10. A looper 8 is provided inside the sewing machine bed 1 below the needle plate 10. The looper 8 is attached to the tip of a looper base 81 whose base is fixed to the looper shaft 80. The looper shaft 80 is constructed at a position away from the needle plate 10 with the axial direction as the front-rear direction, and is repeatedly rotated within a predetermined angular range by transmission from the sewing machine main shaft. The looper base 81 and the looper 8 swing around the looper shaft 80 between a position indicated by a solid line and a position indicated by a broken line in the drawing in response to repeated rotation of the looper shaft 80.

  The looper 8 swings along the lower surface of the needle plate 10 in synchronism with the raising and lowering of the needles 4, 4,..., And the needles 4, 4,. A known operation of forming a seam is performed by capturing the needle thread held by the thread and entwining it with the looper thread. The looper 8 swings away from the needle plate 10 on both the left and right sides with the central portion of the needle plate 10 where the needles 4, 4. The step portion 21 of the sewing machine bed 1 is provided to avoid interference with the swinging region of the looper 8, and the upper surface 20 of the sewing machine bed 1 is made continuous with the upper surface of the needle plate 10 at a higher position. .

  In FIG. 3, a step portion 21 is provided on the right side of the needle plate 10, and the upper surface 20 of the sewing machine bed 1 on the same side is sufficiently lower than the upper surface of the needle plate 10 and is between the upper surface of the needle plate 10. A step shown as H in the figure is secured. As described above, the presser foot 5 descends on the upper surface of the needle plate 10 to hold the sewing fabric. The presser foot 5 is provided with a knife mechanism, and an end portion of a movable knife 6b held by the presser foot 52 and a knife holder 75 connected to the end portion are positioned outside the right presser foot 52. .

  In the present invention, since the step H is secured between the upper surface of the needle plate 10 and the upper surface 20 of the sewing bed 1, a gap more than the step H is generated from the knife holder 75 and the upper surface 20 of the sewing bed 1. Therefore, the operator uses this gap to press the sewing fabric by hand near the presser foot 5 and to push it backward while sliding along the upper surface 20 of the sewing machine bed 1 to assist the feeding of the sewing fabric. Can do.

  As shown in FIGS. 1 and 3, the upper surface 20 of the sewing machine bed 1 is formed by a front cover 22 attached so as to cover the upper part of the sewing machine bed 1 on the right side of the needle plate 10 from the front side. As shown in FIG. 3, the stepped portion 21 is formed by bending the edge of the front cover 22.

  The step portion 21 can be similarly provided on the left side of the needle plate 10. As a result, even on the left side of the presser foot 5, the operator presses the sewing fabric near the needle plate 10 without being troubled by the presence of the fixed knife 6a protruding outside the presser foot 51, and assists the feeding of the sewing fabric. be able to. The above-described stitching can be performed satisfactorily with the aid of such feeding.

  The above effects can be achieved with a simple configuration in which the upper surface 20 of the sewing machine bed 1 is lower than the upper surface of the needle plate 10. The upper surface 20 of the sewing machine bed 1 is only lowered, spreads on both sides of the needle plate 10, and maintains the function of supporting a large sewing fabric sewn on the needle plate 10 from below. Therefore, in the box-type bed double chain stitch sewing machine of the present invention, it is possible to sew the edges of the large-sized sewing fabric by overlapping them with a certain width.

  FIG. 4 is a perspective view of the transmission mechanism 7 to the movable knife 6b. In the figure, 9 is a knife swinging shaft. The knife swinging shaft 9 is a rotating shaft that is horizontally supported inside the sewing machine arm 3 and repeatedly rotates within a predetermined angle range by transmission from the sewing machine main shaft. A swing arm 90 that protrudes radially outward is fixed to one end of the knife swing shaft 9. The swing arm 90 swings in response to repeated rotation of the knife swing shaft 9.

  The transmission mechanism 7 includes a transmission cylinder 70 having a cylindrical shape. The transmission cylinder 70 has one end portion in the axial length direction having a large diameter, and is integrally provided with a female attachment arm 71 projecting radially outward from the large diameter portion. A transmission arm 72 is attached to the other end of the transmission cylinder 70 so as to protrude outward in the radial direction. As shown in FIG. 4, the transmission cylinder 70 is supported by a support cylinder 73 penetrating the lower wall of the sewing machine arm 2 with the female attachment arm 71 facing down so as to freely rotate around the central axis.

  The upper part of the transmission cylinder 70 protrudes inside the sewing machine arm 3. The transmission arm 72 is attached to the protruding end portion of the transmission cylinder 70 and is connected to the swing arm 90 of the female swing shaft 9 via a transmission link 91 having ball joints 92, 92 at both ends. The transmission link 91 transmits the swing of the swing arm 90 due to repeated rotation of the knife swing shaft 9 to the transmission arm 72. The transmission arm 72 swings according to the swing of the swing arm 90, and the transmission cylinder 70 to which the swing arm 72 is fixed rotates repeatedly within an angle range corresponding to the repeated swing of the female swing shaft 9. To do.

  As described above, the transmission cylinder 70 repeatedly rotates around the axis in accordance with the repeated rotation of the female swing shaft 9 transmitted through the swing arm 90, the transmission link 91, and the transmission arm 72. The ball joints 92 and 92 at both ends of the transmission link 91 are provided to absorb relative positional changes between the swinging arm 90 and the transmission arm 72 that swing around different axes.

  A knife mounting arm 71 provided at the lower end of the transmission cylinder 70 is positioned outside the sewing machine arm 3 and has a fixed seat 71a extending downward at the tip. A mounting base 74 is fixed to the fixed seat 71a, and the base of the movable knife 6b is attached to the female holder 75 provided at the lower part of the mounting base 74 as described above. The movable knife 6b is held by a presser foot 52 on the right side of the presser foot 5 so as to be able to reciprocate. The movable knife 6b reciprocates as the knife mounting arm 71 swings in response to repeated rotation of the transmission cylinder 70. The female holder 75 is biased downward by a coil spring 76 provided on the mounting base 74. The coil spring 76 presses the movable knife 6b attached to the knife holder 75 downward, and presses it against the fixed knife 6a inside the introduction path of the presser foot 5. The reciprocating movable knife 6b is in sliding contact with the fixed knife 6a while being pressed by the coil spring 76, and reliably cuts the edge of the sewing fabric.

In FIG. 4 , in order to clearly show the attachment state of the movable knife 6b, the attachment direction of the movable knife 6b is different from the actual direction. The movable knife 6b extends in parallel with the knife swinging shaft 9, and reciprocates in the direction of the sewing machine arm 3 on which the knife swinging shaft 9 is horizontally mounted, that is, in the left-right direction.

  The transmission cylinder 70 holds a cylindrical support bush 32 fitted therein, and a presser bar 31 is inserted into the support bush 32. The lower end of the presser bar 31 protrudes outside the sewing machine arm 3, and the presser foot 5 is attached to the protruding end as described above. The presser bar 31 moves in the vertical direction under the support of the support bush 32, and the presser foot 5 is raised and lowered by this movement.

  The knife drive device 7 includes a transmission cylinder 70 that penetrates the lower part of the sewing machine arm 3 in the vertical direction. The transmission cylinder 70 is repeatedly rotated by transmission from the knife swinging shaft 9, and the movable knife 6 b is connected to the transmission cylinder 70. It reciprocates according to repeated rotation. The transmission cylinder 70 holds a support bush 32 that supports the presser bar 31 so as to be movable up and down, and penetrates the sewing machine arm 3 coaxially with the presser bar 31. In this way, the knife driving device 7 transmits the transmission of the movable knife 6b provided on the presser foot 5 outside the sewing machine arm 3 from the knife swing shaft 9 inside the sewing machine arm 3 to the transmission cylinder that also serves as a support member for the presser bar 31. This is realized by a simple configuration using 70, and the movable knife 6b can be reliably reciprocated.

  FIG. 5 is an external perspective view showing another embodiment of the box bed double chain stitch sewing machine according to the present invention. The sewing machine shown in this figure is a middle cylinder type box-shaped bed double chain stitch sewing machine, and includes a sewing machine bed 1, a pedestal 2 and a sewing machine arm 3 in the same manner as the sewing machine shown in FIG. A needle bar 30 and a presser bar 31 are suspended from the tip of the sewing machine arm 3, and needles 4, 4,... And a presser bar 5 are attached to the lower ends of the needle bar 30 and the presser bar 31, respectively. A needle plate 10 is installed on the upper surface of the sewing machine bed 1 so as to correspond to the lowered positions of the needles 4, 4.

  As shown in the figure, the sewing machine bed 1 has different shapes on the left and right sides of the needle plate 10, and the right side (base end side) of the needle plate 10 extends beyond the needle plate 10 to an appropriate length. A box-like portion 1 a having a flat upper surface 20 extending is formed, and a left side (tip side) of the needle plate 10 is a cylindrical portion 1 b having a flat upper surface 20 within the length range of the needle plate 10.

  The upper surface 20 of the box-shaped portion 1a and the cylindrical portion 1b is both lower than the upper surface of the needle plate 10, and the upper surface 20 of the right-side box-shaped portion 1a is a chamfered portion provided at the right edge of the needle plate 10. 18 (see FIG. 2) and a stepped portion 21 that is obliquely cut away from the needle plate 10 and is continuous with the upper surface of the needle plate 10, and the upper surface 20 of the left tubular portion 1b is located on the left edge of the needle plate 10. The chamfered portion 18 (see FIG. 2) provided is continuous with the upper surface of the needle plate 10.

  As shown in FIG. 2, the presser foot 5 includes left and right presser feet 51 and 52 projecting forward from a presser body 50 attached to the lower end of the presser bar 31, and is held by these presser feet 51 and 52. A knife mechanism having a fixed knife 6a and a movable knife 6b is provided. This knife mechanism operates by driving the knife driving device 7 configured as shown in FIG. 4, and trims the edges of the sewing fabric introduced between the left and right presser feet 51, 52. The configuration and operation of the knife mechanism and knife drive device 7 are the same as those in the embodiment shown in FIGS.

  In the embodiment shown in FIG. 5 as well, the edge of the sewing fabric fed to the needle entry position is trimmed by the operation of the knife mechanism provided in the presser foot 5, so that the stitching with a substantially constant stitch width is performed. Can be implemented. Since the upper surface 20 of the sewing machine bed 1 is lower than the upper surface of the needle plate 10, the operator presses the sewing fabric near the both sides of the needle plate 10 and the presser foot 5 and feeds the sewing fabric. This makes it possible to reliably carry out the stitching of large-sized sewing fabrics.

  In the embodiment of FIG. 5, a cylindrical portion 1b is provided on the front end side of the sewing machine bed 1, and it is possible to cope with sewing of a cylindrical fabric that can be inserted into the cylindrical portion 1b.

1 Sewing bed 3 Sewing arm 4 Needle 5 Presser foot
6a Fixed knife
6b Movable knife 7 Transmission mechanism 8 Looper 9 Knife swing axis
10 Stitch plate
20 Top view
30 needle bar
31 Presser bar 32 Support bush
70 Transmission cylinder
74 Mounting base (Mounting part)

Claims (4)

A box-shaped bed having a flat upper surface for placing a sewing fabric on both sides in the width direction of the needle plate, a needle bar and presser bar supported by a sewing machine arm above the bed, and the needle bar and presser A needle and a presser foot respectively attached to the lower end of the bar; a feed mechanism and a looper provided in the bed below the needle plate; and the presser foot lowered with the presser bar is located on the needle plate. The sewing fabric to which the feed mechanism applies the feed in the longitudinal direction of the needle plate is attached to the lower surface of the needle plate around the needle that moves up and down together with the needle bar and a support shaft parallel to the feed direction. In the box-shaped bed double chain stitch sewing machine which is sewn by the looper swinging along,
The presser foot comprises a knife mechanism having a movable knife that reciprocates in the direction crossing the feeding direction along the upper surface of the needle plate and a fixed knife that slides on the movable knife .
Upper surface of said bed, said at one or both sides of the needle plate, the box-shaped bed double chain stitch sewing machine according to claim lower Citea Rukoto than the upper surface of the needle plate. 2. The box-shaped bed 2 according to claim 1 , wherein the upper surface of the bed and the upper surface of the needle plate are continuous by step portions provided on both sides of the needle plate so as to avoid interference with the swinging area of the looper. Double ring sewing machine. And female swing shaft provided inside the sewing machine arm, convey repetitive rotation of the female swing shaft to the movable knife, according to claim 1 or claim 2 and a transmission mechanism for reciprocating the movable knife Box bed double chain stitch machine. The transmission mechanism is
A transmission cylinder that is supported by penetrating the lower part of the sewing machine arm in the vertical direction, and that internally supports and holds a support bush that supports the lower part of the presser bar;
A transmission link that transmits repetitive rotation of the female swing shaft to the upper part of the transmission cylinder located inside the sewing machine arm;
The box-shaped bed double chain stitch sewing machine according to claim 3 , wherein a mounting portion for the movable knife is provided at a lower portion of the transmission cylinder protruding to the outside of the sewing machine arm.

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