KR100915282B1 - Buttonhole sewing machine - Google Patents

Abstract

In the buttonhole sewing machine, the thread end length of the lower thread is held and cut so as to be as short as possible, and is secured in the next stitch.

The cloth feed table 13, the looper base 31, the needle plate 32 having the needle hole 32b, the turning mechanism 15 for turning the looper base 31, and the bobbin thread after the sewing is finished It is a buttonhole sewing machine 10 having a lower thread cutting device 30, and a lower thread holding means for holding the lower thread to be cut. The lower thread retaining means comprises a lower thread guide surface 32f of the needle plate 32 and a lower thread pressing member 27, and the lower thread cutting device 30 is provided on the looper base 31 and the lower thread near the lower thread retaining means. To cut. The needle plate 32 is provided with an opening 32c which is continuously opened in one direction from the needle hole 32b. Furthermore, it is provided with the guide means which consists of the turning mechanism 15 and the cloth conveyance stand 13 which guide | induce the lower thread after the completion | finish of sewing to be hold | maintained by the lower thread holding means from the opening part 32c.

Description

Buttonhole Sewing Machine {BUTTONHOLE SEWING MACHINE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buttonhole sewing machine for forming a buttonhole stitch by chain stitching, and more particularly, to cutting and retaining the lower thread.

Background Art Conventionally, a buttonhole sewing machine is known which forms a buttonhole by starting operation of a sewing machine and simultaneously performs buttonholehole stitching with a chain stitch around the hole. In such a buttonhole sewing machine, the sewing needle penetrated by the upper thread is moved and shaken, and the looper penetrated by the lower thread is operated to form a stitch around the hole by the cooperation of both.

In a buttonhole sewing machine, as described in Japanese Patent Application Laid-Open No. 9 (1997) -225166, after cutting a stitch, the lower thread (looper thread) connected between the looper and the fabric is cut, and then the looper-side thread end. Mechanism is provided to hold the needle to the next stitch. In the keyhole-shaped buttonhole sewing machine described in the above publication, a guide groove is formed on the needle plate, and after the formation of the stitch, the processing cloth on the needle plate is transferred in a predetermined direction, whereby The lower thread leading to the looper is guided to the inside of the guide groove, and is cut at a position close to the stitched end while the lower thread is held in a holding part provided at the rear end of the needle plate. The looper-side thread end held by the holding portion is embedded in the stitch as the cloth is moved by the progress of the stitch when the next sewing is started.

However, the lower thread cutting and holding mechanism of the above publication has the following problems.

(1) In order to guide the lower thread into the guide groove by moving the upper fabric of the needle plate, the lower thread must be drawn out from the looper by transferring the processing fabric a considerable distance before cutting the lower thread. When the lower thread is drawn out in this way, the thread is wasted, and the end of the thread that needs to be embedded by the next stitch is also long, and the appearance of the stitch is deteriorated, or the end of the thread may be protruded from the stitch formation, thereby degrading the product value.

(2) The lower thread held in the holding portion is slowly driven into the stitch and released from the holding portion as the next stitch proceeds. The bobbin thread that is out of the holding part is on the guide groove, but since the upper part of the guide groove is open and free, it is easy to sew out of the stitch forming part. It is necessary to cut the protruding thread tip by hand.

In the keyhole button-hole sewing machine, since the sewing needle and the needle plate are synchronously pivoted at the keyhole-shaped portion, when the end of the thread that needs to be stuck is long, the end of the thread reaches the turning portion. When the direction of the needle plate relative to the cloth changes, it is easy to escape from the stitches.

(3) The position of the guide groove on the needle plate is the needle drop position (inner needle) on the buttonhole side and the needle drop position (outside needle) on the far side of the buttonhole to guide the thread tip firmly into the stitch. It is formed in between.

By the way, in the buttonhole sewing machine, a sewing machine having a specification that allows a central thread to pass between an upper thread and a lower thread is known. A central threaded hole formed in the needle plate for guiding the central thread into the stitch is formed between the inner needle and the outer needle. That is, since the center thread hole is formed at approximately the same position as the guide groove of the publication, the needle plate on which the guide groove is formed cannot be used for the stitch into which the center thread is driven.

On the other hand, as a lower thread cutting device of a buttonhole sewing machine, one described in Japanese Patent Laid-Open No. 2001-232086 is also known. The lower thread cutting device described in the above publication is installed in a fabric feed table for conveying a processing cloth. After the stitch is finished and the fabric feed table is transferred to a constant home position, the lower thread is cut at the vertically below the stitch end of the fabric.

However, since the lower thread cutting device is fixed to the cloth feeder, when the length of the stitch is changed, it is very cumbersome because the position adjustment or replacement of the parts constituting the lower thread cutting device is necessary. In other words, the stitch length had to be constant.

An object of the present invention is to make a thread end length of a lower thread remaining on a looper after cutting as short as possible in a buttonhole sewing machine having a cutting and holding mechanism of a lower thread, to be secured in the next stitch.

In addition, another object of the present invention is that it is not necessary to adjust the position or replace the parts related to the lower thread cutting, it is possible to cope with various stitch lengths, and to realize the common use of the parts with or without the central thread.

In order to solve the above problems, the invention described in claim 1 is, for example, as shown in Figs.

The needle drop position, which is installed on the sewing machine arm (arm portion 14b), moves up and down while supporting the needle (sewing needle 18) through which the upper thread penetrates, and is further away from the buttonhole where the needle is formed in the fabric. A needle bar 11 for performing a swing motion of the needle in a predetermined needle swing direction so as to alternately fall to the inner needle drop position close to

A conveying means (fabric feed table 13) installed in the sewing machine bed (bed portion 12) and for conveying the processing cloth in at least one direction orthogonal to the needle swing direction;

A looper base 31 provided on the sewing machine bed opposite to the needle bar and provided with a looper (left looper 6, right looper 5) for cooperating with the needle bar to entangle the lower thread to the upper thread;

A needle plate 32 which is provided on the looper base so as to be positioned above the looper, and has a needle hole 32b including two points which are the inner needle drop position and the outer needle drop position;

Turning means (turning mechanism 15) for turning the needle bar and the looper base when stitching,

Lower thread cutting means (lower thread cutting device 30) for cutting the lower thread leading from the looper to the fabric after the buttonhole stitching is finished;

Maintains the lower thread leading to the looper before cutting with the lower thread cutting means, and after cutting, the fabric is conveyed by the conveying means when stitching the next buttonhole, so that the thread end is naturally embedded into the stitch. With means;

In the buttonhole sewing machine 10 which stitches the circumference of the buttonhole H,

Lower thread holding means is installed around the needle plate,

The needle plate is provided with an opening 32c which is continuously opened in one direction from the needle hole.

After the stitch is finished, the lower thread leading from the looper to the processing cloth through the needle hole before cutting the lower thread is provided with guide means for guiding the lower thread to be retained by the lower thread retainer.

According to the invention as set forth in claim 1, after the buttonhole stitching is finished, the lower thread leading from the looper to the processing cloth through the needle hole is led out by the guide means from the opening of the needle plate, and is provided around the needle plate. The lower thread is cut between the looper and the fabric by the lower thread cutting means in this state.

That is, as described in Japanese Laid-Open Patent Publication No. 9 (1997) -225166, the lower thread does not need to be transported a considerable distance before cutting the lower thread to guide the lower thread into the guide groove, so that the lower thread is removed from the needle hole. Since it is only guided to the lower thread holding means around the needle plate, it is not drawn out like the above-mentioned publication.

Therefore, the bobbin thread leading from the looper to the processing cloth can be cut in a very short state by the bobbin cutting means. That is, the end of the thread remaining on the processed fabric can be about the distance from the end point of the stitch to the needle plate, and the end of the thread remaining on the looper side held by the lower thread holding means can be shortened to the length to the needle plate. Therefore, the end of the thread to be embedded in the next stitch is short, so that it can be surely inserted without deteriorating in appearance.

Moreover, the amount of drawout of the lower thread is small, and the waste of thread is also less.

Here, the "transferring the processing cloth in at least one direction substantially orthogonal to the needle swing direction" with respect to the conveying means means that it may be comprised so that it may move to another direction.

In addition, the lower thread holding means may be provided around the needle plate, and specifically, the needle plate itself may be deformed, or a plate spring shape member capable of fitting the lower thread to the needle plate may be attached.

Alternatively, as in claim 2, the needle plate and another member may be configured.

That is, the invention described in claim 2 is a buttonhole sewing machine according to claim 1,

Lower thread holding means,

A lower thread guide portion (lower thread guide surface 32f) which is installed on the needle plate and guides the end portion of the cut lower thread into the stitch to be formed next;

It is characterized by consisting of a lower thread pressing member (lower thread presser 27) to press the lower thread relative to the lower thread guide portion.

According to the invention according to claim 2, the lower thread is inserted into and supported by the lower thread guide portion being pressed by the lower thread pressing member, and is guided by the lower thread guide portion when forming the next stitch, so that it is surely embedded in the stitch. In addition, when the needle plate is made small, the needle hole, which is the position at which the stitches are formed, and the lower thread guide portion are brought close, and the end of the thread can be kept until just before being completely embedded in the stitch, and it does not escape from the stitch.

In addition, since the lower thread holding means also serves as a guide member as well as holding, the configuration is simplified accordingly.

In the invention according to claim 3, in the buttonhole sewing machine according to claim 2, the lower thread pressurizing member is driven by a driving means (upper thread cutting driving means 60) common to the lower thread cutting means, so that the lower thread with respect to the lower thread guide portion Press to paste.

According to the invention of claim 3, since the lower thread pressing member is driven by a driving means common to the lower thread cutting means, the entire structure can be simplified. Moreover, since the drive source is the same, it is hardly deviated by adjusting only once regarding the timing of the lower thread pressurization and the lower thread cutting.

The invention according to claim 4 is the buttonhole sewing machine according to claim 2 or 3,

Upper thread cutting means (upper thread cutting device 7) for cutting the upper thread after the buttonhole stitching is finished, and upper thread cutting driving means 60 for driving the upper thread cutting means,

At least one of the lower thread cutting means and the lower thread pressurizing member is driven by the upper thread cutting driving means.

According to the invention of claim 4, at least one of the lower thread cutting means and the lower thread pressing member is driven by the upper thread cutting driving means, thereby simplifying the overall structure.

The invention according to claim 5 is the buttonhole sewing machine according to any one of claims 2 to 4,

And an adjusting means (stopper screw 21 and nut 22) capable of adjusting the minimum distance that the lower thread guide portion and the lower thread pressing member approach to maintain the lower thread.

According to the invention of claim 5, since the minimum distance that the lower thread guide portion and the lower thread pressurizing member approach to maintain the lower thread can be adjusted by the adjusting means, an appropriate holding force can be achieved according to the thickness or property of the lower thread to be maintained. Therefore, the holding force is weak, so that the lower thread does not come out at the start of sewing or, on the contrary, the holding force is so strong that the lower thread is not cut.

In other words, since the force when the lower thread pressing member is in contact with the lower thread guide portion can be adjusted, the impact on the needle plate, which is an important component when holding the lower thread, can be prevented.

The invention according to claim 6 is the buttonhole sewing machine according to any one of claims 1 to 5,

The guide means comprises the pivot means and the conveying means, and after the buttonhole stitching is finished, the lower thread leading from the looper to the fabric through the needle hole is first conveyed by the conveying means to the fabric of the needle plate. It moves to the opening, and then guides the lower thread holding means along the outer circumferential surface of the needle plate by turning the looper base together with the needle plate by the turning means.

According to the invention as set forth in claim 6, the lower thread penetrating the needle hole is first introduced by the conveying means to the opening portion, and then the turning needle plate is rotated by the turning means to induce the lower thread along the outer circumference of the needle plate and the lower thread holding means. Induce. That is, since the mechanism originally installed in the buttonhole sewing machine is used instead of installing a new mechanism only for the induction means, cost and space can be saved as compared with the case of installing a dedicated mechanism.

In addition, by appropriately controlling the conveying amount by the conveying means, the withdrawal amount of the lower thread can be changed, and as a result, the length of the lower thread remaining on the fabric cloth can be selected.

In this case, the movement of the conveying or turning may be performed only for the guidance of the lower thread. In addition, an operation for starting the next buttonhole stitch can also be used. In this case, it is efficient in that it does not require time of operation only for induction of the lower thread in terms of time.

The invention according to claim 7, in the buttonhole sewing machine according to any one of claims 1 to 6,

The lower thread holding means is provided so as to substantially coincide with the up and down plane perpendicular to the straight line between the straight line connecting the inner needle drop position and the outer needle drop position inside the needle hole.

According to the invention as set forth in claim 7, the lower thread holding means is provided between the inner needle dropping position inside the needle hole and the straight line connecting the outer needle dropping position so as to substantially coincide with the plane in the vertical direction orthogonal to the straight line. The lower thread held by the means is naturally guided between the inner needle drop position and the outer needle drop position at the start of the stitch and securely embedded in the stitch.

The invention according to claim 8 is the buttonhole bet sewing machine according to any one of claims 1 to 7,

The lower thread retaining means is provided below the needle hole.

According to the invention as set forth in claim 8, since the lower thread holding means is provided below the needle hole, it is easy to form a hole for passing the center thread through the needle plate so that the parts can be shared regardless of the need of the center thread. have.

The invention according to claim 9 is the buttonhole sewing machine according to any one of claims 1 to 8,

The said lower thread cutting means is characterized by cutting the lower thread after the lower thread is held by the lower thread holding means and before the fabric is conveyed by the conveying means.

According to the invention according to claim 9, the lower thread cutting means cuts the lower thread leading from the looper to the processing cloth after the lower thread is held by the lower thread holding means and before the processing cloth is transferred. 9 (1997) -225166, the lower thread leading from the looper to the fabric is not drawn out long. Accordingly, the lower thread cutting means cuts the lower thread leading from the looper to the processing cloth in a very short state. That is, the end of the thread left on the fabric is about the distance from the end point of the stitch to the needle plate, and the end of the thread held by the lower thread holding means, i.e., the end of the thread left on the looper side, is shortened to the length of the needle plate. As a result, the end of the thread to be embedded in the next stitch is short, so that the appearance can be secured without deterioration.

Moreover, the amount of withdrawal of the lower thread is small, so there is less waste of thread.

The invention according to claim 10 is the buttonhole sewing machine according to any one of claims 1 to 9, wherein the lower thread cutting means is provided on a looper base.

According to the invention according to claim 10, since the lower thread cutting means is provided on the looper base, the cutting position is constant so that the lower thread cutting tool can be made independent of the sewing length, and thus the parts of the lower thread cutting tool are adjusted according to the sewing length. · There is no need to change it and there is no restriction that the sewing length should be constant.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail based on drawing.

The buttonhole sewing machine 10 (hereinafter simply referred to as the sewing machine 10), which is an example of the present invention shown in FIG. 1, forms a buttonhole stitch with a chain stitch by automatic control. The sewing machine 10 may form various stitches by selecting a pattern. Here, for example, a stitch W is formed around the buttonhole H made up of the keyhole portion h1 and the linear straight portion h2 shown in Fig. 9B. The stitch W consists of a right sewing portion w1, a keyhole sewing portion w2 around the keyhole shape portion h1, a left sewing portion w3, and a straight fastening portion w4.

The sewing machine 10 of FIG. 1 is mainly comprised of the bed part 12 which comprises a substantially rectangular box shape, the vertical body part 14a which stands up from the back part of the bed part 12, and the vertical body part ( It has an arm portion 14b which protrudes forward from 14a) and protrudes, and is placed on the sewing machine table (not shown) with the bottom cover 16 interposed therebetween. In the front part of the arm part 14b, the needle bar 11 provided with the sewing needle 18 which the upper thread passes through is provided in the lower end part, and it is possible to move up and down, and to move the needle in the left-right direction (X direction of FIG. It is installed to allow oscillating motion.

Furthermore, the sewing machine 10 includes an operation panel 90 for the operator to make various settings, and a control device 110 for controlling a series of sewing operations of the sewing machine 10 (see FIG. 7).

Although not shown, the upper shaft is installed in the arm portion 14b so as to extend in the front-rear direction. On the other hand, inside the bed 12 is installed so that the lower axis extends in the front and rear direction. The upper shaft and the lower shaft are connected via a timing belt, and are rotated in synchronism with the main shaft motor 81.

The needle bar 11 is connected to the upper shaft through a needle bar up and down drive mechanism and a needle swing mechanism inside the arm portion 14b. In addition, since the needle swing mechanism is similar to the well known swing mechanism provided with a conventional buttonhole sewing machine in which the swing width of the needle can be mechanically adjusted, a description thereof will be omitted. In other words, in the present embodiment, the swing width is set in advance by mechanical adjustment.

Inside the bed 12, a looper base 31 having a left looper 6 through which the lower thread passes and a right looper 5 to assist the left looper 6 is provided to face the needle bar 11. . The left and right loopers 6 and 5 are connected to the lower shaft via a drive mechanism not shown. The needle bar 11 and the looper base 31 operate synchronously as in the conventional sewing machine, and form a stitch by intertwining the lower thread on the upper thread by the cooperation of both.

In addition, the needle bar 11 and the looper base 31 are connected to the swing motor (a swing pulse motor) 84 and a swing mechanism (a swing means; 15) having a timing belt, and rotate about a vertical axis. Thus, a radial stitch (keyhole sewing portion; w2) is formed at the periphery of the keyhole shape h1 of the button hole H. As shown in FIG.

On the upper surface of the bed portion 12, a fabric feed table (transfer means) 13 on which a processing cloth is set is installed. On the upper surface of the cloth feed table 13, cloth presses 2 for pressing the fabric on both sides of the buttonhole to be formed are provided.

The cloth feed table 13 constitutes a thin rectangular box body as a whole, and is formed by the drive mechanism composed of the X-axis motor 82, the Y-axis motor 83, and the like installed inside the bed 12. Under control, it is possible to move in the left-right direction (X direction) and the front-rear direction (Y direction).

In a state where the position of the cloth feed table 13 is determined at a predetermined home position, a fixed scalpel (not shown) and a scalpel base 4 are disposed above and below a predetermined position for buttonhole formation of the fabric to be placed on the upper surface thereof. Is set to face.

The scalpel base 4 is provided behind the needle bar 11, and a fixed scalpel is provided on the bed portion 12 so as to face the scalpel base 4. The scalpel base 4 is driven up and down by a cloth cutting motor (pulse motor) 85 provided above.

At the time of sewing, first, the cloth cutting motor 85 is driven at the origin position to lower the scalpel base 4 toward the fixed scalpel, and the cutting cloth set between the scalpel base 4 and the fixed scalpel is pressed to cut the button hole. (Here, a keyhole-shaped button hole H) is formed.

Then, the cloth transfer table 13 is vertically downward of the sewing needle 18 of the processing cloth placed at the sewing start position, that is, the cloth transfer table 13, from the home position forward by the operation of the start switch 92 (FIG. 7). Driven to move. The stitches around the button hole H start from the lower end of the right sewing part w1, go through the keyhole-shaped sewing part w2, to the left sewing part w3, and finally, the straight fastening part w4 Are sewn in order. In order to sew in this order, the cloth feed table 13 starts to move from the sewing start position in the Y direction so that the apex of the button hole H (the tip of the keyhole shape h1) It moves forward until it becomes a corresponding state, and it returns to the sewing end position which is substantially the same as a sewing start position toward the back after that.

When sewing is finished, the cloth transfer table 13 is controlled to return to the home position from the sewing end position. In this embodiment, when setting the processing cloth, the cloth feed table 13 moves to a predetermined setting position.

The sewing machine 10 is provided with an upper thread cutting device 7 and a lower thread cutting device 30 for cutting the upper thread and the lower thread, respectively, on the looper base 31. As will be described later, in the sewing machine 10, after the sewing is finished, the upper thread is cut by the upper thread cutting device 7 before the cloth feed table 13 starts to move to the origin, and the lower thread is cut at the intermediate position toward the origin. The lower thread is cut by the device 30.

In the present invention, since the upper thread cutting device 7 is composed of a conventional known structure, detailed description thereof will be omitted. However, since the lower thread cutting device 30 characteristic of this invention uses the drive source common to the upper thread cutting device 7, in this embodiment, the drive mechanism of the upper thread cutting device 7 is demonstrated below first. .

The upper thread cutting device 7 as the upper thread cutting means is formed by arranging each member in the front and rear direction inside the bed portion 12 and the upper thread cutting scalpel 78 on the looper base 31 as shown in FIG. It consists of the upper thread cutting drive means (60).

The upper thread cutting operation arm 78a for operating the upper thread cutting blade 78 can rotate about an axis parallel to the front and rear direction of the sewing machine 10 with respect to the attachment member 31a fixed to the looper base 31. It is attached so that. The upper thread cutting blade 78 is fixed to the upper portion of the upper thread cutting operation arm 78a. In FIG. 2, the lower thread cutting device 30 is briefly shown, and the bed part 12 is only a schematic shape of a dashed line.

The upper thread cutting operation arm 78a has one end of a spring for an operation arm not shown in the drawing, and is pressed by the operating arm spring to rotate in a predetermined direction, so that the upper thread cutting blade 78 is placed in a predetermined cutting standby position. It is supposed to be located. In addition, the rotation point of the upper thread cutting operation arm 78a is the center rotation shaft 42 which will be described later.

The upper thread cutting operation arm 78a is provided with a projection 78c, the projection 78c is pressed downward by the upper thread cutting driving means 60, and the upper thread cutting operation arm 78a is opposed to the spring for the operation arm. The upper thread cutting scalpel 78 performs the upper thread cutting operation by rotating in a direction opposite to the predetermined direction.

The upper thread cutting drive means 60 is comprised by the thread cutting cylinder 86, the thread cutting link 61, the thread cutting drive shaft 64, the thread cutting drive arm 69, etc.

The base end of the seal cutting cylinder 86 is supported by the cylinder bracket 66 fixed to the bed part 12 by the fixing screws 66a and 66a so that rotation is possible. In addition, the thread cutting cylinder 86 is made to advance and retract the rod 86a attached to the front part, and the extrusion amount of the rod 86a is always constant.

One end of the thread cutting link 61 formed in a substantially T-shape is rotatably connected to the distal end of the rod 86a via a cylinder knuckle 67. The intermediate part of the thread cutting link 61 is supported by the rotating shaft 61a so that rotation to the bed part 12 is possible. On the other hand, the other end part of the thread cutting link 61 is connected to the thread cutting drive shaft 64 which extends in the substantially up-down direction so that rotation is possible. The thread cutting drive arm 69 is provided in the upper end of the thread cutting drive shaft 64. In addition, when the looper base 31 is located at a rotation angle of 180 degrees, the thread cutting drive arm 69 and the protrusion 78c of the upper thread cutting blade 78 overlap vertically, and if it is 0 degrees, the lower thread cutting device 30 described later The protruding pin 26d and the thread cutting drive arm 69 overlap each other.

According to the upper thread cutting drive means 60, the thread cutting drive arm 69 operates in conjunction with the shanghai movement of the thread cutting drive shaft 64 by the driving force of the thread cutting cylinder 86. FIG.

That is, as shown in FIG. 2, when the thread cutting cylinder 86 is in an OFF state, the rod 86a is extruded, and the thread cutting drive arm 69 will be stopped at the top dead center at this time. On the other hand, when the thread cutting cylinder 86 is turned on, the rod 86a is retracted, and the thread cutting drive arm 69 moves downward by the counterclockwise rotation of the thread cutting link 61 to stop at the bottom dead center. It becomes a state. At this time, when the looper base 31 is in the rotational position of 180 degrees, the upper thread cutting scalpel 78 located at the cutting standby position is operated by the thread cutting driving arm 69 pressed downward to operate the upper thread. This is cut. When the thread cutting cylinder 86 is turned off again, the thread cutting drive arm 69 moves to the top dead center and the upper thread cutting blade 78 returns to the cutting standby position by the pressing force of the spring for the operating arm. do.

When the looper base 31 is in the rotational position of 0 degrees, the lower thread cutting device 30 is driven by the thread cutting drive arm 69 to cut the lower thread. This will be described later.

Next, the lower thread cutting device 30 which is a lower thread cutting means is demonstrated.

First, the structure is demonstrated based on FIG. The lower thread cutting device 30 is installed on the looper base 31, and is composed of a lower thread cutting blade 20, a lower thread presser 27, and the like, and is machined with the left looper 6 in the vicinity of the needle plate 32 after sewing. The lower thread is cut between the fabrics. The left looper 6 is fixed to the looper attachment rod 6a shown in FIG. 4 so that the lower thread passes. Further, the looper attachment stand 6a is configured to be able to swing the central rotation shaft 42 to be described later in the plane orthogonal to the ground of FIG. 4. As a result, the left looper 6 performs a predetermined reciprocating motion under the needle plate 32 during sewing. The right looper 5 also reciprocates in synchronism with the left looper 6, and assists the motion that the lower thread penetrating the left looper 6 is entangled with the upper thread penetrating the sewing needle 18.

The lower thread cutting blade 20 is formed in a substantially hook shape, and is fixed to the lower thread cutting blade arm 26 by a fixing screw 41 at its proximal end so as to operate together with the lower thread cutting blade arm 26.

The blade part 20a which cuts a lower thread is formed in one end part of the lower thread cutting blade 20. On the other hand, the other side is the avoidance part 20b (FIG. 5) polished so that it may not be cut | disconnected even if a lower thread contacts.

The lower thread cutting scalpel 26 extends from the main body portion 26a to which the lower thread cutting scalpel 20 is fixed and slightly bent along the right side of FIG. 3 from the main body portion 26a to a screw hole (not shown). Screw support portion 26b through which the first stopper screw 33 is inserted, and pin support portion 26c on which protruding pins 26d extending from the main body portion 26a to the left and protruding backward are fixed. do.

The lower part of the main body part 26a is attached so that it may rotate about this center of rotation with respect to the center axis of rotation 42 inserted into the attachment member 31a so as to be rotatable.

The 1st stopper screw 33 of the screw support part 26b is screwed a predetermined amount with the screw hole of the screw support part 26b, and the lower surface part 33a is in contact with the looper base 31. As shown in FIG. In addition, one end of the lower thread cutting spring 25 (only a part of which is shown in FIG. 3 and the other part is indicated by a broken line) is caught in the middle of the screw support part 26b, and the other end of the lower thread cutting spring 25 is connected to the looper base 31. Is hanging The lower thread cutting female arm 26 is always pressed clockwise in FIG. 3 by the lower thread cutting spring 25, and in the initial state, the lower surface portion 33a of the first stopper screw 33 is attached to the looper base 31. As shown in FIG. It stops in contact but it is retracted so that the lower thread cutting | disconnection scalpel 20 may not be in the position which interrupts sewing. That is, the height H1 of the 1st stopper screw 33 which protrudes below from the screw support part 26b determines the initial position of the lower thread cutting | disconnection scalpel 26. As shown in FIG.

The protruding pin 26d of the pin support part 26c overlaps with the said thread cutting drive arm 69 up and down when the rotational position of the looper base 31 is 0 degree | times (FIG. 4).

The second stopper screw 34 is screwed a predetermined amount through the pin support portion 26c so as to penetrate up and down, and the lower surface portion 34a protrudes from the pin support portion 26c. At the time of cutting the lower thread, the rotational position of the looper base 31 becomes 0 degrees, and when the protruding pin 26d is pressed by the lowering of the thread cutting drive arm 69, the lower thread cutting scalpel 26 is the lower thread cutting spring. Against counter 25 and driven counterclockwise in FIG. At this time, when the lower surface portion 34a of the second stopper screw 34 abuts on the looper base 31, it can no longer be rotated counterclockwise. The length of the second stopper screw 34 protruding downward from the pin support 26c in this way is such that the lower thread cutting scalpel 20 is rotated by a necessary distance so that the lower thread is cut firmly and no unnecessary operation is performed. The operation end position of the scalpel 26 is determined.

The recessed surface 26e which is a flat recessed part is formed in the place shown with the oblique line on the back surface of the main body part 26a. The side surface (hereinafter concave side surface) 26f which forms this concave surface 26e fits the screw 36 which can rotate coaxially with this at the time of counterclockwise rotation of the lower thread cutting female arm 26. It touches and pressurizes in the same direction.

The lower thread presser 27 is provided so that it may oppose the lower thread cut | disconnect scalpel 20 between the needle plates 32 mentioned later. As shown in Fig. 6, the lower thread presser 27 holds the lower thread by pressing the lower thread pressing surface 27a formed on the tip portion 27f with the lower thread guide surface 32f of the needle plate 32.

The lower thread presser 27 passes through the lower thread presser pin 28 at its center portion. Both ends of the lower thread presser pin 28 are supported by the lower thread presser attachment 24 so that the lower thread presser 27 can pivot about the lower thread presser pin 28 with respect to the lower thread presser attachment 24. do. The lower thread presser attachment base 24 is formed in a substantially square shape when viewed from the rear and in a substantially triangular shape when viewed from the side.

In addition, a lower thread presser return spring 23 is provided below the lower thread presser mounting base 24, and the lower thread presser return spring 23 is in contact with the lower thread presser mounting base 24 and the looper base 31. In the direction of widening, that is, the lower thread presser attachment base 24 is pressed toward the needle plate 32.

The screw hole 24a is formed in the side surface of the lower thread presser attachment stand 24 (FIG. 5), and the stopper screw 21 is inserted through the said screw hole 24a. The tip of the stopper screw 21 is in contact with the side surface 31b of the attachment member 31a. By changing the screwing amount of the stopper screw 21 with respect to the screw hole 24a, the distance to the side surface 31b of the lower thread presser mounting base 24 is changed, thereby causing the needle plate 32 of the tip portion 27f. The distance with respect to the center axis of rotation 42 is changed. Specifically, the lower thread pressing surface 27a of the lower thread presser 27 and the lower thread guide surface 32f of the needle plate 32 have a stopper screw ( The stopper screw 21 is fixed by adjusting 21 and tightening the nut 22 in that state. That is, the adjusting means of this invention is comprised by the stopper screw 21 and the nut 22. As shown in FIG.

In addition, as mentioned above, the lower thread presser mounting stand 24 and the lower thread presser 27 are pressurized by the lower thread presser return spring 23 in the direction in which the lower thread pressurizing surface 27a is close to the lower thread guide surface 32f. . However, when the stopper screw 21 is in contact with the side surface 31b of the attachment member 31a, the lower thread stopper 27 is prevented from further facing the needle plate 32. That is, it can also be prevented that the lower thread stopper 27 exerts a strong impact on the needle plate 32 by adjusting by an adjustment means.

In addition, about the distance between the lower thread pressurizing surface 27a and the lower thread guide surface 32f, for example, if the lower thread is to be strongly retained, the distance may be approximately 0 mm, and if the lower thread is quite thick, the distance of the thickness of the lower thread may be provided. .

The lower thread presser 27 is bent in the way so that the tip part 27f may face the lower thread guide surface 32f of the needle plate 32. Details of the tip portion 27f will be described later.

The lower end part 27g of the lower thread stopper 27 is bifurcated, an inverted U-shaped opening is formed, and a stopper pin 29 passes through the opening (FIGS. 3 and 4). The head part of the stopper pin 29 is caught by the lower end part 27g as shown in FIG. 3, and the front end is being fixed to the lower thread presser attachment base 24. As shown in FIG. Furthermore, the lower thread presser spring 40 is attached to the inner side of the lower end portion 27g around the axis of the stopper pin 29. The lower end portion 27g of the lower thread presser 27 swings backward by the lower thread presser spring 40, so that the side surface 32h of the needle plate 32 side 32h (dot display portion in FIG. 6) is moved. It is pressurized by the opposing surface 27d which opposes the said side surface 32h in the triangular pyramid part 27c of the tip part 27f. However, the lower end portion 27g is pressed by the lower thread presser spring 40 to abut against the rear surface of the head portion of the stopper pin 29, so that the lower end portion 27g of the lower thread presser 27 goes further backward. It cannot swing, and the opposing surface 27d is not pressed against the side surface 32h excessively.

In addition, (b) of FIG. 11 expands and shows the state which the side surface 32h and the opposing surface 27d contact.

The inner side of the lower thread presser attachment base 24 projects continuously to the lower side of the screw 37, and becomes the continuous protrusion 24c. The continuous protrusion 24c overlaps the protrusion, and furthermore, the flat lower thread presser point base 35 formed to a size extending to the lower inner side of the main body portion 26a of the lower thread cutting female arm 26 overlaps the continuous protrusion 24c. 24c and the lower thread stopper point base 35 are being fixed substantially integrally by the screw 36. Further, in the continuous projection 24c, a longitudinal hole is formed in the longitudinal direction for inserting the screw 36, and the continuous projection 24c (the lower thread presser attachment 24) of the lower thread release point stand 35 is formed. In the state where the height position is adjusted, it is fixed by the screw 36.

The central rotary shaft 42 is inserted into the lower portion of the lower threader presser stand 35, and the lower threader presser stand 35 and the lower threader presser mounting stand 24 are rotatable about the central pivoter 42. have.

The concave side surface 26f presses the lower thread presser point base 35 and the lower thread presser attachment base 24 and the screw 36 when the lower thread cutting female arm 26 rotates counterclockwise, thereby lowering the presser thread. The mounting table 24, that is, the lower thread presser 27, is rotated counterclockwise about the central rotation shaft 42. As shown in FIG.

As shown in FIG. 6, the needle plate 32 has a needle hole 32b through which the sewing needle 18 is inserted, and is supported by a leg 38 having a screw hole 38a formed at the center thereof. The needle plate 32 is fixed to the attachment member 31a by the screw 37 in the screw hole 38a.

The needle hole 32b is elongated horizontally so that the sewing needle 18 can swing in the needle hole 32b when stitching. In Fig. 5, the needle dropping positions inside the needle hole 32b are indicated by points P1 and P2. At the time of sewing, the point P1 is at the inner needle drop position close to the button hole, and the point P2 is at the outer needle drop position far from the button hole (see FIG. 9 (d)). In addition, the specific positions of the points P1 and P2 with respect to the needle hole 32b can be changed as appropriate.

The opening part 32c is formed so that a part of the needle plate 32 may be cut | disconnected continuously to the needle hole 32b. 6, the peripheral part 32e on the left side from the needle hole 32b is formed in substantially circular arc shape, and the lower edge part 32d (part shown with a thick line) is chamfered and polished. As will be described later, the lower thread is relatively out of the opening 32c and toward the lower thread guide surface 32f along the lower edge 32d before cutting after sewing, since the lower edge 32d is circular and polished. The bobbin thread can move smoothly without being pulled out more than necessary.

In the leg part 38, the upper side of the screw hole 38a is formed narrower, and the lower thread guide surface (lower thread guide part; 32f) is formed in the side surface so that it may continue to the lower surface of the needle plate 32. As shown in FIG. The lower thread guide surface 32f sandwiches the lower thread after cutting between the lower thread pressing surface 27a formed at the tip portion 27f of the lower thread stopper 27. That is, the lower thread holding means of the present invention is constituted by the lower thread guide surface 32f and the lower thread presser 27.

The lower thread guide surface 32f is provided in a plane perpendicular to the straight line in the middle of the straight line connecting the inner needle drop position P1 and the outer needle drop position P2 inside the needle hole 32b. The lower thread held by the lower thread retaining means is approximately coincident with the plane and is guided into the stitch naturally when sewing is started.

Moreover, the protruding surface 27b is formed in the front-end | tip part 27f of the lower thread presser 27 so that it may protrude more than the lower thread pressing surface 27a. The protruding surface 27b is in surface contact with the rear side surface 32g formed at a step with the lower thread guide surface 32f on the upper rear of the leg portion 38. On the other hand, as described above, a triangular pyramid-shaped triangular pyramid portion 27c is formed on the upper surface of the tip portion 27f, and the opposite surface 27d of the triangular pyramid portion 27c is the side of the peripheral portion 32e of the needle plate 32. It is in contact with (32h).

When the lower thread is sandwiched between the lower thread guide surface 32f and the lower thread pressing surface 27a, each of the protruding surface 27b, the rear side 32g, the opposing surface 27d and the side surface 32h abuts, The bobbin thread will never come out.

7 is a view showing the control device 110 of the sewing machine 10.

The control device 110 shown in FIG. 7 includes a ROM (Read Only Memory) 111, a RAM (Random Access Memory; 112), a CPU (Central Processing Unit; 113), and an EEPROM (Electrically Erasable and Programmable Read Only Memory; 115). And so on.

The control unit 110 is connected to the operation panel 90 and the start switch 92 via an interface I / F 114, and the main shaft motor 81, the X-axis motor 82, and the Y-axis motor 83. Various actuators, such as the turning motor 84, the cloth cutting motor 85, and the thread cutting cylinder 86, are connected.

In addition, a spindle motor for driving each motor between the interface 114 and the spindle motor 81, the X-axis motor 82, the Y-axis motor 83, the turning motor 84, and the cloth cutting motor 85. The driving circuit 81a, the X-axis motor driving circuit 82a, the Y-axis motor driving circuit 83a, the turning motor driving circuit 84a, the cloth cutting motor driving circuit 85a exist, and the interface 114 and the seal A seal cutting cylinder drive solenoid valve 86a exists between the cutting cylinders 86.

In addition, the control device 110 includes an X for detecting the home position of each of the X-axis motor 82, the Y-axis motor 83, the turning motor 84, and the cloth cutting motor 85 through the interface 114. The axis origin sensor 82b, the Y axis origin sensor 83b, the swing origin sensor 84b, and the cloth cutting origin sensor 85b are connected.

The ROM 111 controls various actuators such as the spindle motor 81, the X-axis motor 82, the Y-axis motor 83, the turning motor 84, the cloth cutting motor 85, and the thread cutting cylinder 86. The control program and the control data for sewing are written.

The EEPROM 115 stores a plurality of pattern data and, when the value of the data item in the pattern data is changed through the operation panel 90, also stores the value and the like. Moreover, the RAM 112 functions as a memory area temporarily used at the time of various processes during sewing. The pattern data refers to a series of setting data necessary for forming buttonhole sewing, such as sewing length and the number of needles, for example.

When the start signal is input from the start switch 92, the CPU 113 relates to buttonhole sewing including cutting, sewing, and upper thread cutting and bobbin cutting processing according to the control program and control data of the ROM 111. Control a series of processes.

That is, the CPU 113 drives the rotation control of the spindle motor 81 by the spindle motor drive circuit 81a connected through the interface 114. The main shaft motor 81 drives the upper shaft which drives the sewing needle 18 up and down or oscillates left and right, or the looper mechanism which forms a stitch in cooperation with the sewing needle 18.

In addition, the CPU 113 drives the X-axis motor 82 and the Y-axis motor 83 by the X-axis motor driving circuit 82a or the Y-axis motor driving circuit 83a connected through the interface 114. While controlling, the cloth feed table 13 is driven in a predetermined direction.

Further, the CPU 113 controls and drives the swing motor 84 by the swing motor drive circuit 84a connected through the interface 114. The sewing needle 18 and the looper base 31 rotate (rotate) by this turning motor 84, and the keyhole sewing part w2 which is a radial stitch around the keyhole shape h1 (FIG. 9) b)).

In addition, the CPU 113 drives the cloth cutting motor 85 by the cloth cutting motor drive circuit 85a connected through the interface 114 to move the scalpel base 4 up and down.

In addition, the CPU 113 drives the thread cutting cylinder 86 by the thread cutting cylinder drive solenoid valve 86a connected through the interface 114 at a predetermined timing after the end of sewing.

In the series of processing described above, the CPU 113 detects the states of the X-axis origin sensor 82b, the Y-axis origin sensor 83b, the swing origin sensor 84b, and the cloth cutting origin sensor 85b, respectively. By driving the axial motor 82, the Y-axis motor 83, the turning motor 84, and the cloth cutting motor 85, the movement position of the cloth feed table 13, the needle bar 11 or the looper base 31 The turning angle, the lowering position of the scalpel base 4, and the like are controlled.

Next, the operation of the sewing machine 10 having the above-described configuration will be described with reference to FIGS. 3 and 4 and 8 to 13 with respect to the lower thread cutting device 30. In FIGS. 8 and 9, members such as button holes H and stitches W formed in the work cloth S and FIG. 4, and the needle plate 32 under the work cloth S are shown. In addition, the lower thread T derived from the left looper 6 is indicated by a dotted line and a black circle, and in particular, the black circle indicates the position of the lower thread T at approximately the same height as the needle plate 32. The upper thread leading from the stitches W to the sewing needle 18 is omitted.

The sewing of the buttonhole H and the stitch W is finished by the sewing of the linear fixation part w4. At this time, as shown in Fig. 8A, the looper base 31 is rotated such that the longitudinal direction of the needle hole 32b of the needle plate 32 is parallel to the needle swing direction of the linear fastening portion w4. The position is in a state of 270 degrees. The positional relationship with the lower thread cutting | disconnection scalpel 20, the tip part 27f of the lower thread stopper 27, and the needle plate 32 of the looper 6 at this time is as shown. This is the state of FIG. 3. The lower thread guide surface 32f of the needle plate 32 and the lower thread pressing surface 27a of the lower thread presser 27 are in contact with each other.

Subsequently, the swing mechanism 15 is driven by the swing motor 84 so that the looper base 31 is rotated 90 degrees clockwise and the rotational position is 180 degrees. At this time, the lower thread T in the needle hole 32b comes to the position which sees the opening part 32c rearward. In the rotational position of 180 degrees, the upper thread is cut by the upper thread cutting scalpel 78 by driving the thread cutting cylinder 86.

Next, by driving the Y-axis motor 83, the cloth feed table 13 is moved backwards by a predetermined distance (corresponding to a distance from the needle hole 32b to the inlet of the opening 32c, for example, 4 mm). As shown in Fig. 8 (c) or Fig. 10, the lower thread T leading to the sewing end position of the stitch W is also moved to reach the opening 32c. As shown in FIG. 10, the protruding pins 26d of the lower thread cutting female arm 26 are at positions opposite to the thread cutting driving arm 69. In addition, the white circle | round | yen near the needle board 32 of FIGS. 10-12 shows the lower thread T in the state before one.

Thereafter, the looper base 31 is pivotally driven at a rotational position of 0 degrees. As a result, the needle plate 32 rotates clockwise, and the lower thread T, which has reached the opening portion 32c, has the periphery 32e of the needle plate 32 as shown in FIGS. 8D and 11. In contact with the lower edge part 32d, it is guide | induced relatively counterclockwise.

Finally, as shown in FIGS. 8E and 12, the rotational position is 0 degrees, and the lower thread T is the lower thread guide surface 32f of the needle plate 32 and the lower thread pressing surface of the lower thread presser 27. It reaches to the position which enters between (27a). The above-mentioned FIG. 4 is a state of the rotation position of said 0 degree | times, and the protruding pin 26d of the lower thread cut | disconnected female arm 26 is located under the thread cutting drive arm 69. As shown in FIG. In this way, the lower thread (T) is guided by the movement of the swing mechanism (15) and the cloth feed table (13), and these are the guide means of the present invention.

The dotted lines A, B, and C of FIG. 4 show the relative movement of the lower thread T with respect to the needle plate 32 when the looper base 31 is rotated. That is, in Figs. 8A and 8B, the lower thread T is inside the needle hole 32b as indicated by the dotted line A. Figs. Next, in the state of FIG. 8C after the cloth feed table 13 moves, the opening 32c reaches the opening 32c. Furthermore, as the needle plate 32 is rotated 180 degrees, the state becomes the state of FIG. 8E, and at this time, the swing path of the lower thread cutting scalpel 20 is blocked as indicated by the dotted line C of FIG. 4.

After (e) of FIG. 8, the thread cutting drive arm 69 descends by pushing the thread cutting cylinder 86, and presses the protruding pin 26d downward. As a result, the lower thread cutting blade 20 starts to rotate counterclockwise in FIG. 3 along with the lower thread cutting blade arm 26 against the pressing force of the lower thread cutting spring 25. At this time, it avoids, removing it so that the lower thread T may not be cut | disconnected by the avoidance part 20b of the lower thread cutting | disconnection scalpel 20. FIG.

The screw 36 is pressed by the concave side 26f inside the lower thread cutting female arm 26 during rotation, and the lower thread presser 27 together with the lower thread presser mounting base 24 is also in the same direction about the central rotation shaft 42. Go to the meeting. Thereby, as shown in FIG.8 (f), the blade part 20a of the lower thread cutting | disconnection scalpel 20 totally jumps over the lower thread T, and the tip part 27f of the lower thread presser 27 is also removed from the needle plate 32. As shown in FIG. Slightly falls The lower thread fixed at the part which the lower thread presser 27 and the needle board 32 contact | connects will be in contact with the lower thread guide surface 32f like FIG. The rotation operation of the lower thread cutting blade arm 26 (the lower thread cutting blade 20) and the lower thread stopper 27 stops at a position where the second stopper screw 34 abuts on the looper base 31 as shown in FIG.

In addition, although the lower end presser 27 is pressurized so that the tip part 27f may face the needle board 32 by the lower thread presser spring 40 as mentioned above, it restrict | limits with the stopper pin 29 so that it may not progress excessively. Since the tip portion 27f does not exceed the most protruding portion of the peripheral portion 32e formed in an arc shape.

When the thread cutting cylinder 86 returns to its original state, the thread cutting drive arm 69 returns upward. Thus, the lower thread cutting blade 20 and the lower thread cutting blade arm 26 are driven by the pressing force of the lower thread cutting spring 25, and the lower thread clamp 27 and the lower thread clamp mounting bracket 24 are the lower thread clamp return spring 23. The return operation is started by the pressing force of.

In the return operation, since the lower thread presser 27 is pressed by the lower thread presser spring 40 so that the tip portion 27f faces the needle plate 32, the opposing surface 27d of the triangular pyramid portion 27c is a needle. It moves while contacting the peripheral part 32e of the board 32. As shown in FIG. When the lower thread presser 27 returns to the position where the stopper screw 21 abuts against the side surface 31b of the attachment member 31a, the lower thread T across the lower thread guide surface 32f is moved to the lower thread pressing surface 27a. Press to hold both. At this time, each of the protruding surface 27b, the rear side surface 32g, the opposing surface 27d and the side surface 32h also comes into contact with each other so that the lower thread T cannot come out.

Immediately after the lower thread T is sandwiched between the lower thread guide surface 32f and the lower thread pressing surface 27a, the blade portion 20a of the lower thread cutting scalpel 20 cuts the lower thread T, and FIG. Return to the initial position as shown.

Thereafter, as shown in FIG. 9B, the cloth feed table 13 is driven by the X-axis pulse motor 82 and the Y-axis pulse motor 83 to return to the home position at the rear side.

When the next sewing is started, first, the cloth cutting motor 85 is driven at the origin position of the cloth transfer table 13 to form a buttonhole H, and then the cloth transfer table 13 is moved to a predetermined sewing position. It is sent to the front and starts sewing from the right side sewing part w1 as shown in FIG.9 (c). The lower thread T leading to the left looper 6 cut and held after the previous sewing has a guide surface formed of the lower thread guide surface 32f and the lower thread pressurizing surface 27a from the inner needle drop position of the needle hole 32b. Since it is between the outer needle dropping positions, as the needle plate 32 moves relatively backwards, it is naturally embedded in the stitch as shown in FIG. 9 (d).

In addition, in FIG.9 (c), (d), a white circle shows the position of the needle in sewing, and the bobbin thread used for sewing supplied from the left looper 6 is abbreviate | omitted.

According to the above sewing machine 10, after completion of the stitch, the lower thread T leading from the left looper 6 to the processing cloth S through the needle hole 32b is first opened by the cloth transfer table 13 by the opening 32c. ), Then the needle plate 32 is rotated by the turning mechanism 15 to guide the lower thread guide surface 32f along the lower edge portion 32d of the outer circumference of the needle plate 32. The lower thread cutting device 30 cuts the lower thread held by the lower thread guide surface 32f and the lower thread pressurizing surface 27a of the lower thread presser 27 in the vicinity thereof before being transferred by the fabric transition cloth feed table 13. do.

That is, since the lower thread T is only guided from the needle hole 32b to the lower thread guide surface 32f behind the needle plate 32 via the opening 32c, the above-described Japanese Patent Application Laid-Open No. 9 (1997)- It is not withdrawn as long as 225166.

Therefore, the thread end remaining on the fabric cloth after cutting is about the distance from the end point of the stitch to the needle plate 32, and the thread end remaining on the left looper 6 side held by the lower thread holding means is the needle plate 32. Can be as short as Thereby, the external appearance does not become bad because the end of the thread which gets stuck in the next stitch is short.

Furthermore, since the lower thread cutting device 30 is provided on the looper base 31, the lower thread can be cut at a constant position with respect to the end position of the stitch. If the cutting position is a fixed position with respect to the end of the stitch, it means that the lower thread cutting tool and the sewing length are not related.There is no need to adjust or replace the parts of the lower thread cutting tool according to the sewing length. There is no need to keep constant, so you can sew to free length.

In addition, the amount of drawout of the lower thread is small, so there is less waste of the thread.

The short end of the thread, the lower thread is pressed to the lower thread guide surface 32f by the lower thread pressurizing surface 27a of the lower thread presser 27, and it is held firmly, and the lower thread guide surface 32f is inside the needle hole 32b. Due to the fact that it is provided in the vertical plane perpendicular to the straight line at the middle of the straight line connecting the needle drop position P1 and the outer needle drop position P2, the bobbin thread is guided firmly in the next stitch and is naturally embedded in the stitch. .

Furthermore, if the needle plate 32 is made small or if the lower thread pressing surface 27a and the lower thread guide surface 32f opposed thereto are formed as long as allowed in the direction of the needle hole 32b, the stitches are formed. Since the needle hole 32b and the lower thread guide surface 32f are close to each other, it can be maintained until just before the thread tip is completely nailed in.

On the other hand, by appropriately controlling the feed amount by the cloth feed table 13, the remaining length of the lower thread of the processing cloth S side can be selected, it can be made constant, or can be changed suitably, and the degree of freedom is high.

In addition, since the lower thread is guided using the cloth feed table 13 or the turning mechanism 15 which is originally installed in the buttonhole sewing machine, the cost and space can be saved as compared with the case where a guide-only mechanism is provided.

Furthermore, since the thread is connected to the left looper 6 from the working cloth S to the left looper 6 and cannot be moved freely, the lower thread is first maintained, so that it can be reliably maintained. In addition, since the bobbin thread is kept in tension and is cut, it can be surely cut.

Since the lower thread presser 27 and the lower thread cutting blade 20 are driven by the driving means common to the upper thread cutting drive means 60, the overall structure can be simplified. In addition, if only one adjustment is made regarding the timing of clamping of the bobbin thread and cutting of the bobbin thread, the driving source is the same, so that there is almost no deviation.

In addition, since the minimum distance that the lower thread presser 27 approaches the lower thread guide surface 32f can be adjusted by the adjusting means composed of the stopper screw 21 and the nut 22, the holding force is appropriate for the thickness or the property of the lower thread to be maintained. Since the holding force is weak and the lower thread is released when starting sewing, the holding force is so strong that the lower thread is not cut. In other words, since the force when the lower thread presser 27 comes into contact with the lower thread guide surface 32f can be adjusted, it is possible to prevent the impact of the needle plate 32, which is an important component when the lower thread is held. have.

Since the lower thread guide surface 32f is provided below the needle hole 32b, it is also possible to form a hole for passing the central thread in approximately the same plane as the needle hole 32b of the needle plate 32. For example, what is necessary is just to form the hole which lets a center thread pass in the position shown by the code | symbol R of FIG. Therefore, the parts can be shared regardless of whether the center seal is required.

In addition, this invention is not limited to said embodiment.

For example, in the present embodiment, the bobbin cutting means is provided on the looper base to shorten the thread tip leading from the looper to the processing cloth, and is configured so that it is not necessary to adjust or replace parts of the bobbin cutting mechanism or the like depending on the sewing length. The lower thread cutting means is not limited to the above-described configuration as long as the thread tip leading from the looper to the processing cloth is shortened. That is, since the lower thread holding means can hold the lower thread without drawing the lower thread long when the processing cloth is held, the lower thread cutting means is a lower thread cutter fixed to a conveyer as described in, for example, Japanese Patent Laid-Open No. 2001-232086. Even if the bobbin thread is driven after the bobbin thread is retained, the bobbin cutting tool from the looper to the bobbin can be shortened by driving the bobbin cutter tool.

Further, it may be applied to a buttonhole sewing machine for forming a keyhole of a shape different from the above example or for making a keyhole-shaped buttonhole which does not sew the sewing machine. It can also be applied to a sewing machine.

Incidentally, in the above description, the lower thread is cut immediately after the holding. However, if the lower thread is cut before the fabric is moved, it may not be necessary immediately after the holding.

Moreover, in the above embodiment, the lower thread after cutting is configured to be held by the lower thread guide surface 32f of the needle plate and the lower thread pressing surface 27a of the lower thread presser, but a retaining member made of a leaf spring or the like is provided on the rear of the needle plate. It may be. If comprised in this way, the said lower thread stopper 27 will become unnecessary, and a structure can be simplified more.

Moreover, although the lower thread part was guided by the lower edge part 32d of the needle plate 32 periphery part 32e, the lower thread which led out of the needle plate 32 from the opening part 32c of the needle plate 32 was removed. And other members such as the attachment member 31a.

According to the invention as set forth in claim 1, after the buttonhole stitching is finished, the lower thread leading from the looper to the processing cloth through the needle hole is led out from the opening of the needle plate by guide means, and is installed around the needle plate. It is held by the lower thread holding means, in which the lower thread can be cut between the looper and the fabric by the lower thread cutting means. That is, since the lower thread is only guided from the needle hole to the lower thread holding means around the needle plate, the lower thread is not drawn out as long as Japanese Patent Laid-Open No. 9-225166.

Therefore, the bobbin thread leading from the looper to the processing cloth can be cut in a very short state by the bobbin cutting means. That is, the end of the thread remaining on the fabric can be made about the distance from the end point of the stitch to the needle plate, and the end of the thread remaining on the looper side held by the lower thread holding means can be shortened to the length to the needle plate. Therefore, the end of the thread to be embedded in the next sewing is short, so that the appearance can be securely inserted without deterioration.

Moreover, the amount of drawout of the lower thread is small, and the waste of thread is also less.

According to the invention according to claim 2, the lower thread is inserted into and supported by the lower thread guide portion being pressed by the lower thread pressing member, and is guided by the lower thread guide portion when forming the next stitch, so that it is surely embedded in the stitch. In addition, when the needle plate is made small, the needle hole, which is the position at which the stitches are formed, and the lower thread guide portion are close to each other, so that the end of the thread can be maintained until it is completely embedded in the stitch, so that it does not escape from the stitch.

Further, since the lower thread holding means also serves as a guide member as well as holding, the configuration is simplified accordingly.

According to the invention of claim 3, since the lower thread pressing member is driven by a driving means common to the lower thread cutting means, the entire structure can be simplified. Moreover, since the drive source is the same, it is hardly deviated by adjusting only once about the timing of the lower thread pressurization and the lower thread cutting.

According to the invention of claim 4, at least one of the lower thread cutting means and the lower thread pressing member is driven by the upper thread cutting driving means, thereby simplifying the overall structure.

According to the invention of claim 5, since the minimum distance that the lower thread guide portion and the lower thread pressurizing member approach to maintain the lower thread is adjusted by the adjusting means, an appropriate holding force can be achieved in accordance with the thickness or property of the lower thread to be maintained, Low holding force prevents the lower thread from slipping out at the start of sewing or, conversely, the holding force is so strong that the lower thread is not cut.

In other words, since the force when the lower thread pressurizing member is in contact with the lower thread guide portion can be adjusted, the impact can be prevented from being applied to the needle plate, which is an important component when the lower thread is held.

According to the invention as set forth in claim 6, first, the lower thread penetrating the needle hole is introduced to the opening by the conveying means, and then the needle plate is rotated by the turning means to guide the lower thread along the outer circumference of the needle plate to maintain the lower thread. To the. That is, since the mechanism originally installed in the buttonhole sewing machine is used instead of installing a new mechanism only for the induction means, cost and space can be saved as compared with the case of installing a dedicated mechanism.

In addition, since the withdrawal amount of the lower thread can be changed by appropriately controlling the conveying amount by the conveying means, and thus the length of the lower thread remaining on the fabric cloth can be selected, it can be made constant or appropriately changed and the degree of freedom is high.

According to the invention as set forth in claim 7, the lower thread holding means is provided between the inner needle drop position inside the needle hole and the straight line connecting the outer needle drop position so as to substantially coincide with the up and down plane perpendicular to the straight line. The lower thread held by the holding means is naturally guided between the inner needle drop position and the outer needle drop position at the start of the stitch and is firmly embedded in the stitch.

According to the invention as set forth in claim 8, since the lower thread holding means is provided below the needle hole, it is easy to form a hole for passing the center thread through the needle plate so that the parts can be shared regardless of the need of the center thread. have.

According to the invention as set forth in claim 9, the lower thread cutting means cuts the lower thread leading from the looper to the processing cloth after the lower thread is held by the lower thread holding means and before the processing cloth is transferred. Like -225166, the bobbin thread from the looper to the fabric is not drawn out long. Accordingly, the lower thread cutting means cuts the lower thread leading from the looper to the processing cloth in a very short state. As a result, the thread end remaining on the fabric cloth is about the distance from the end point of the stitch to the needle plate, and the thread end remaining on the looper side held by the lower thread holding means is shortened to the length to the needle plate. As a result, the end of the thread to be lodged in the next stitch is short, so that the appearance is not deteriorated and can be lodged surely.

Moreover, since the amount of drawout of the lower thread is small, there is less waste of the thread.

According to the invention of claim 10, since the lower thread cutting means is provided on the looper base, the cutting position is constant so that the lower thread cutting tool can be made independent of the stitch length, so that the parts of the lower thread cutting tool are adjusted according to the sewing length.・ There is no need to change and there is no restriction that the sewing length should be constant.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an example of a buttonhole sewing machine of the present invention, where (a) is an overall perspective view and (b) is a side view showing a broken part of the bed.

2 is a plan view showing the configuration of the upper thread cutting driving means.

3 is a plan view with the lower thread cutting device in front.

4 is a side view illustrating the lower thread cutting device of FIG. 3.

5 is a plan view seen from above of the lower thread cutting device.

6 is a perspective view of the needle plate member.

7 is a control block diagram of the buttonhole sewing machine shown in FIG.

8 is a view showing in sequence the operation of the lower thread cutting device shown in FIG.

9 is a continuation of FIG. 8.

10 is a plan view seen from above showing details of the lower thread cutting device in FIG. 8C.

FIG. 11 is a plan view seen from above showing details of the lower thread cutting device in FIG. 8 (d). FIG.

FIG. 12 is a plan view seen from above showing details of the lower thread cutting device in FIG. 8 (e).

It is a figure which shows the state in which the 2nd stopper pin of the lower thread cutting | disconnection cutting | arm arm of the lower thread cutting device abutted on the looper base just before cutting the lower thread.

Description of the main parts of the drawing

5: Right Looper 6: Left Looper

7: upper thread cutting device (upper thread cutting means) 10: buttonhole sewing machine

11: needle bar 12: bed portion (sewing machine bed)

14b: arm part (sewing machine arm) 15: swing mechanism (turn means)

18: sewing needle (needle) 13: cloth feed table (feeding means)

20: lower thread cutting blade 21: stopper screw (adjustment means)

22: Nut (adjustment means) 24: Lower thread presser attachment stand

26: cutting arm of the lower thread 26d: protruding pin

27: Lower thread presser (bottom thread pressurizing member) 27a: Lower thread pressurized surface

30: lower thread cutting device 31: looper base

32: needle plate 32c: opening

32d: lower edge 32e: periphery

32f: Lower thread guide surface (lower thread guide) 60: Upper thread cutting drive means

69: thread cutting drive arm 86: thread cutting cylinder

78: upper thread cutting blade 81: spindle motor

W: Stitch H: Buttonhole

Claims (10)

It is provided on the sewing machine arm and moves up and down while supporting the needle penetrated by the upper thread, and the needle alternately falls to the inner needle drop position close to the far outer needle drop position with respect to the button hole formed in the processing cloth. A needle bar for performing a swinging motion of the needle in the needle swinging direction, A conveying means installed in the sewing machine bed and conveying the processing cloth in at least one direction orthogonal to the needle swing direction; A looper base provided on the sewing machine bed opposite to the needle bar and having a looper for cooperating with the needle bar to entangle the lower thread to the upper thread; The looper base is provided so as to be located above the looper, and has a needle hole including two points which are the inner needle drop position and the outer needle drop position, and is continuously opened in one direction from the needle hole. A needle plate provided with an opening, Turning means for turning the needle bar and the looper base when stitching, Lower thread cutting means for cutting the lower thread leading from the looper to the fabric after the buttonhole stitching is finished; It is installed around the needle plate, and retains the lower thread leading to the looper before cutting with the lower thread cutting means, and after cutting, the fabric is conveyed by the conveying means at the next buttonhole stitching, so that the thread tip is inserted into the stitch. A lower thread holding means for keeping the nail in; After the buttonhole stitching is finished, the lower thread leading from the looper to the processing cloth through the needle hole before cutting the lower thread is provided with guide means for guiding the lower thread to be held by the lower thread holding means, As a buttonhole sewing machine which stitches the circumference of a buttonhole, The guide means comprises the turning means and the transfer means, and after the buttonhole stitching, the lower thread leading from the looper to the workpiece fabric through the needle hole is first transferred to the opening of the needle plate by transferring the workpiece cloth by the transfer means. A buttonhole sewing machine, characterized in that it is guided to the lower thread holding means along the outer circumferential surface of the needle plate by moving and then turning the looper base together with the needle plate by the turning means. The method of claim 1, wherein the lower thread holding means, A lower thread guide part installed at the needle plate to guide the end of the cut lower thread into the next stitch to be formed; A buttonhole sewing machine, characterized in that consisting of a lower thread pressing member for pressing the lower thread relative to the lower thread guide portion. The lower thread pressing member of claim 2, A buttonhole sewing machine characterized in that it is driven by a driving means common to the lower thread cutting means and presses the lower thread against the lower thread guide portion. The upper thread cutting means for cutting the upper thread after the buttonhole stitching is finished, and the upper thread cutting driving means for driving the upper thread cutting means, At least one of the lower thread cutting means and the lower thread pressing member is driven by the upper thread cutting drive means. The buttonhole sewing machine according to claim 2 or 3, further comprising adjusting means for adjusting a minimum distance that the lower thread guide portion and the lower thread pressing member approach to maintain the lower thread. 4. The lower thread holding means is installed so as to coincide with an up and down plane perpendicular to the straight line between a straight line connecting the inner needle drop position and the outer needle drop position inside the needle hole. A buttonhole sewing machine, characterized in that. The buttonhole sewing machine according to any one of claims 1 to 3, wherein the lower thread holding means is provided below the needle hole. 4. The lower thread cutting means according to any one of claims 1 to 3, wherein the lower thread cutting means cuts the lower thread after the lower thread is held by the lower thread holding means and before the fabric is transferred by the transfer means. Buttonhole sewing machine. The buttonhole sewing machine according to any one of claims 1 to 3, wherein the lower thread cutting means is provided on a looper base. delete