JPS6017553B2 - How to sew corners on a needle-feed lockstitch sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a corner stitching method for making corner stitches appropriate when corner stitching is performed using a sewing machine that forms regular stitches.

Conventionally, in needle-feed lockstitch sewing machines in which the needle swings backward in the cloth-feeding direction almost in synchronization with the lower feed dog to perform cloth-feeding motion and form a lockstitch in cooperation with a horizontal hook, corner For example, after the needle thread loop has been captured by the hook tip, the sewing machine is stopped at the lower needle layer at the main shaft rotation angle (point A in Figure 5) where the needle has slightly risen, and the fabric is moved around the needle in that lower layer. The sewing machine was driven again after turning at a predetermined angle, but when the sewing machine was driven after turning the fabric at the corner, the needle rose from point A and was placed above the throat plate, as is clear from Figure 5. After the needle comes out, the needle moves forward in the cloth feed direction together with the lower feed dog.
The thread take-up moves up behind the needle bar and pulls up the needle thread.

When the needle reaches the top dead center, the feed dog has moved forward in the cloth feeding direction together with the needle. For example, in Fig. 7, the needle hole of the feed dog has moved from point Na to point Nb, and the bobbin thread U is In order to pull up the needle thread T that is intertwined between the bobbin thread U between Nc and Nd, the thread take-up is It is necessary to pull U horizontally (in the direction of arrow a) toward needle drop point Na, and then pull it up further upwards, and it is necessary to pull it up with a force greater than the force required to pull it upwards as in normal straight stitching. However, since the thread take-up stroke is constant and the needle thread tension is normally set to match the pulling force during straight sewing, the needle thread tension (pulling force) is insufficient at the corners, and this lack of pulling force causes the sewing to fail. The knot points remained on the back side of the cloth, causing so-called "tangles" S. Also, when forming a corner stitch on a lockstitch sewing machine with two needles, for example, when the left needle is set to the inside of the corner stitch as shown in Figures 9 and 10, the inside (left) needle is placed at the needle drop point Nd. A needle lower counterfeit (point A in Figure 5) in which the upper layer is put into a rest state by a well-known means, and a predetermined number of stitches are continuously formed using only the outer (right) needle, and the needle tip pierces the fabric at the needle drop point Na. Stop the sewing machine, turn the fabric counterclockwise at a predetermined angle (Fig. 9) around the outer needle, and then start the sewing machine again.
After the outer stitch is formed to a position corresponding to the rest position Nd of the inner stitch, the inner needle is returned to its working state to perform double-needle stitching. Similarly, when using the right needle on the inside of a corner, the inner needle is at rest at the needle drop point corresponding to the inner corner, and a stitch is formed using only the outer needle to the needle drop point corresponding to the outer corner. Stop the sewing machine directly below the needle, turn the fabric clockwise at a predetermined angle, use the outside needle again to form an outside stitch to the position corresponding to the needle drop point corresponding to the inside corner, and then turn the inside needle again. I tried to return it to its working state and perform double needle stitching. When this two-needle lockstitch sewing machine has the above-mentioned needle feeding function, "tearing" S occurs at the outer corner for the same reason as mentioned above.

The object of the present invention is to prevent the above-mentioned "tangling" at the corners and improve the quality of sewn products. Embodiments of the invention will be described with reference to the drawings.

The sewing machine shown in Fig. 1 is a needle-feed lockstitch sewing machine, and the needle bars 2a and 2b, which have needles la and lb separately fixed to their lower ends and are arranged in parallel to the left and right (crossing the cloth feeding direction), are driven by a drive source. It is linked to a rotating main shaft (not shown) that is moved by a certain motor M (Fig. 4), and enables fabric feeding movement that moves up and down and reciprocates along the fabric feeding direction, cooperating with the lower feeding teeth 9. Although not shown, a pair of horizontal hooks equipped with a well-known bobbin thread absorbing means described in Japanese Utility Model Publication No. 11896/1989 etc. are equipped with both needles la and lb.
They are arranged below the throat plate (not shown) so that they can be worked separately to form the main stitch.

Further, one of the needles 2a and 2b can be put into a rest state individually at a predetermined position corresponding to the needle upper layer by a well-known needle resting mechanism 3. No. 1983-60330 (Unexamined Japanese Patent Publication No. 52-1431)
No. 47) Controlled by operating the operating lever 4 as described in the specification and drawings. When the operating lever 4 is in the intermediate position (Fig. 1), both needles la and lb are activated to perform double-needle sewing, and when it is in the one position where it is rotated clockwise, one needle, for example, in Fig. 1, is operated. The left needle lb is put in a resting state, and when the needle is in the other position for turning in the counterclockwise direction, the other needle, for example, the right needle la in FIG. 1, is put in a resting state to perform single-needle stitching. At the rear of the sewing machine, a cam plate 32 is fixed on the rotation axis of the operation lever 4, and a cam plate 32 is fixed to the rotation axis of the operation lever 4. The distal end of the engaging body 34 is formed into a forked shape, and is rotatably supported by the sewing machine frame 1 and is always subjected to an acting force to the left in FIG. The inner end surface of the locking portion 34a with one side bent forward is arranged opposite to the tip surface of the cam plate 32, and the operating lever 4
is at the intermediate position, the inner end surface of the engaging portion 34a engages with the protrusion 32a of the cam plate 32, and the engaging body 34 is moved to the right rotation position in FIG. 2 against the force of the coil spring. , and when the operating lever 4 is moved to one or the other position, the protrusion 32a of the cam plate 32 has the protrusion 32a on both sides of the protrusion 32b or 32.
c, and the engagement body 34 is moved to the second position by the force of the coiled spring.
While rotating to the left in the figure, the cam plate 32 is maintained at the rotating position against the acting force of the stop mechanism 8. A permanent magnet 35 is fixed to the upper part of the other side 34b of the two-pronged part of the engaging body 34, and the engaging part 34a is engaged with the cutout part 32b or 32c of the cam plate 32 facing above the permanent magnet 35. In other words, only when the engaging body 34 rotates to the left in FIG. 2, the permanent magnet 3
A magnetic sensing body 36 that senses magnetism No. 5 is fixed to the machine frame 1. Further, the tip of the plunger 38 of the electromagnet 37 is fixed to the support portion 34c that protrudes to the side of the engaging body 34, and the electromagnet 37
At the time of action, the plunger is sucked and the engaging body 34 is wound, and the engaging portion 34a engages the protrusion 3 of the cam plate 32 against the acting force of the spring.
2a so as to rotate to the right in FIG. 5 moves to the main axis and threads T of both needles la and lb
6 is a well-known thread tension device (main tension device) having a tension disc on the same axis so as to apply thread tension to needle threads Ta and Th separately. A pair of well-known thread tension devices (sub tension devices) are arranged so that the paths of the needle threads Ta, m on the side of the thread supply source are separated from the main tension device 6, and apply thread tension to each of the needle threads Ta, Th. It is.

The feed amount of the lower feed dog 9 and needle combs 2a, 2b is adjusted by a known feed adjustment cam body 10' shown in FIG.

That is, the adjustment cam body 10 supported on the machine frame so as to be rotatable about a support shaft 11 along the horizontal direction is connected to a link (not shown) that provides a feed motion to the lower feed dog 9 and the needle threads 2a, 2b in conjunction with the main shaft. ) to connect the spindle 12 to the dial and other operating members (
The cam surface is opposed to the tip of the adjustment shaft 13 that advances and retreats in the bag line direction (left and right direction in Figure 2) in connection with the operation of the cam (not shown). Engage the surface with the tip of the adjustment ball 13. Retract the shaft 13 (right side in Figure 3)
When the tip thereof is engaged with the cam surface 10a, the adjustment cam 1 is in the state shown in FIG. When the forward feed of the corresponding feed amount is performed and the adjusting shaft 13 is advanced to engage the tip end with the cam portion 10b, the feed amount becomes zero.

An elongated hole 14 is formed at the rear end of the adjustment cam 10. The elongated hole 14 extends vertically and extends along the parallax direction of the support shaft 11. Support shaft 11
An operating arm 16 whose rear end is rotatable about a support shaft 15 having an axis parallel to the rotation axis has a pin 17 fixed to its tip along the rotation axis direction, and swings the pin 17 into the elongated hole 14. The connecting body 18 whose upper end is locked to the middle part of the working arm 16 has its lower end connected to the plunger (not shown) of the electromagnet Mg2, and the middle part projects laterally to form an engaging part 18a.
The lower surface engageably faces the upper surface of a locking body 19 fixed to the machine frame. The working arm 16 repositions the pin 17 in the elongated hole 14 to allow rotation of the cam body 10 about the support shaft 11 when the electromagnet Mg2 is inactive, and engages the locking body 19 when the electromagnet Mg2 is energized. The connecting body 18 until the engaging portion 18a engages.
When the cam body 10 is in the normal feeding state as shown in FIG. Then, the cam plate 10 is rotated counterclockwise, and in the zero feed state (FIG. 3) or reverse feed state, the pin 17 only moves within the elongated hole 14, but the cam body 101 is not rotated. Next, the electric circuit will be explained.

NP is a needle position detection means, which separately detects the spindle rotation angle corresponding to the vertical position of the needle and generates an upper layer signal and a lower layer signal, and CS is a stitch number setting means, which detects the main shaft rotation angle corresponding to the vertical position of the needle and generates an upper layer signal and a lower layer signal. The number of stitches to be stitched by the needle is set, and a setting signal of a different digital code is generated corresponding to the set number. The LSW is a start switch that generates a start signal when a pedal (not shown) is depressed, and the skin SW is a start switch when the operating lever 4 is in the intermediate position (
This is a sewing state detection switch (magnetic sensor 36) which is turned off when the sewing machine is in a double-needle state, and turned on when one or the other is wrong (a single-needle state).

NC is the aforementioned Tokubuta No. 51-60330 (Tokukan Showa 52-1)
This is a corner stitching control circuit for performing automatic corner stitching described in No. 43147), and is a sewing state detection switch MISW.
The motor M is driven in conjunction with the generation of the on signal of the next start switch LSW, and the number of upper layer signals generated from the needle position detection means NP determines the number of stitches. When the value is equal to the set value of the means CS, the motor M is stopped so that the sewing machine is in the lower needle layer, and the motor M is driven in conjunction with generation of a start signal of the next start switch LSW;
When the number of upper layer signals is equal to the set value, electromagnet Mg1
The motor drive circuit MD and the electromagnetic actuation circuit MAI are controlled so as to energize (37).

TC is a needle thread control circuit, and each start switch LS
W, corner stitching control circuit NC, sewing condition detection switch skin SW
, and acts in conjunction with the generation of a start signal from the pedal start switch LSW at the outer corner, and controls the electromagnet Mg2 for a certain period of time △t required for the main shaft to rotate once at a low speed. The electromagnetic actuating circuit MA2 is controlled to operate. The present invention has the above structure, and its operation will be explained next. Start stitch formation from the double-needle sewing state with the operating lever 4 in the intermediate position, and at a predetermined position Nd in front of the corner of the fabric (not shown), at the main shaft rotation angle of the needle lower layer (point A in Figure 5). Stop the sewing machine and, for example,
As shown in Fig. 10, when sewing a corner using the left needle lb as the inner needle, when the operating lever 4 is rotated to one position, the pause mechanism 3 puts the needle thread 2b in the pause state and the cam plate 32 also moves to the second position. 2, the notch 32b engages and holds the engaging part 34a of the engaging body 34, and the magnetic sensing body 36 senses the magnetism of the permanent magnet 35, and the sewing state detection switch is activated. SW generates an on signal.

Further, the set value of the stitch number setting means CS is set to "3". In this state, when the pedal is depressed and a start signal is generated from the start switch W, the corner stitch control circuit NC drives the motor M via the motor drive circuit MD, and the outer needle la
In connection with generation of the third stitch upper layer signal from the needle position detecting means NP after a stitch is formed by the sewing machine, the motor M is stopped so as to stop the main shaft of the sewing machine at the rotation angle of point A in FIG.

The operator pulls up the presser foot 39 above the throat plate and moves it to the needle drop point N.
At step a, the cloth is turned at a predetermined angle in the counterclockwise direction (FIG. 9) around the outer needle la whose needle tip is introduced into the cloth. Next, when the presser foot 39 is lowered onto the throat plate and the pedal is depressed again, the stitches are continued to be formed only by the outer needle la in response to the activation signal from the activation switch LSW. Needle drop point Na
The needle la, which has been re-raised from the spindle rotation angle point A, gradually rises and comes out above the throat plate, and while this needle is positioned above the needle slope, the thread take-up 5 rises and pulls up the needle thread Ta. , when a starting signal is generated at the outer corner, the needle thread control circuit TC acts, and the electromagnet Mg2 acts for a certain period of time via the electromagnetic actuating circuit MA2, and the operating arm 16 rotates clockwise (Fig. 2) to activate the cam. The body 10 is rotated counterclockwise, and the feed amount of the needle bars 2a, 2b and the lower feed dog 9 is made zero.

Therefore, the needle thread Ta due to the rise of the thread take-up 5 at the outer corner
When the material is pulled up, the fabric feed amount becomes zero, the needle hole of the lower feed dog does not move at point Na, and the tension of the needle thread Ta is sufficient to pull the bobbin thread Ua upward. Create eye knots in the cloth.

In addition, in this example, the patent application No. 51-60 $0 (
This method performs corner stitching based on the corner stitching control device described in JP-A No. 52-143147), but a microcomputer controls the driving speed of the sewing machine and stops the sewing machine. The sewing may be controlled or the electromagnet Mg2 may be controlled.

Furthermore, in this embodiment, the explanation was given for corner stitching with the left needle on the inside, but the feed amount is zero at the outer corner when corner sewing with the right needle on the inside, or at the corner on a single needle needle feed sewing machine. A similar effect can be obtained in any case.

Further, in this embodiment, the feed adjustment cam 10 is controlled by the electromagnet Mg2, but it may be controlled by a stepping motor, a servo motor, or the like. As described above, according to the present invention, in a needle-feed lockstitch sewing machine that transfers the fabric along a straight line and knots the needle thread and bobbin thread to form a lockstitch line, the needle is moved after the fabric is transferred. When the fabric is stopped in the fabric penetration state, the fabric is rotated at a specific angle around the needle, and then the fabric is further transferred, the fabric feed amount can be adjusted only when the first stitch is formed after the fabric rotation. By setting it to zero, the needle hole of the feed dog does not move at the corner, so the needle thread can create a seam knot point in the fabric with tension that pulls the bobbin thread upward, just like when sewing a straight line. This has the effect of preventing "tangling" and making the seams vertical and improving the quality of the sewn product.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of the needle feed lockstitch sewing machine with two needles of this embodiment, Fig. 2 is a perspective view of the needle control mechanism, Fig. 3 is a front view of the feed adjustment section, and Fig. Figure 4 is an electric circuit, Figure 5 is an explanatory diagram showing a motion diaphragm of a needle feed sewing machine, Figure 6 is an explanatory diagram showing a lock stitch, Figure 7 is an explanatory diagram showing corner stitching by a needle feed lock stitch sewing machine, FIG. 8 is an explanatory diagram showing corner stitching using a twin needle, and FIGS. 9 and 10 are explanatory diagrams showing the case where corner stitching is performed using the left needle as the inner needle in a twin needle feed sewing machine.

Figure 2 Figure 3 Figure 1 Figure 4 Figure 6 Figure 7 Figure 8 Figure 5 Figure 9 Figure 10

Claims (1)

[Claims] 1. In a needle-feed lockstitch sewing machine that moves the fabric along a straight line and knots the needle thread and bobbin thread to form a lockstitch line, after the fabric is transferred and the needle stops moving through the fabric, , The corner of a needle-feed lockstitch sewing machine that makes the fabric feed amount zero only when forming the first stitch after rotating the fabric, when the fabric is rotated at a specific angle around its needle and then further transferred. How to sew.