KR20030030912A - Method and apparatus for forming seams - Google Patents

Abstract

PURPOSE: To perform sewing not to make stitch thread appear on a surface of a sewing material when putting the surfaces of two sewing materials together, sewing the ends, then turning the sewn part to an inner side and splitting open the sewing materials in a thick leather material such as an automobile seat or furniture. CONSTITUTION: By a cloth feeder for a sewing machine forming stitches, the stitches are successively formed on cloth by repeating processings of forming a plurality of the stitches by feeding the cloth in one direction for n+1 stitches or more and then forming the stitches by feeding it in the opposite direction for n stitches by the same feed amount.

Description

Seam Forming Method and Apparatus {METHOD AND APPARATUS FOR FORMING SEAMS}

The present invention relates to a method and apparatus for forming a seam of a sewing machine, and in particular for sewing leather products, such as automobile seats and furniture, sewing two ends of the sewing material together to seal the ends thereof, and then sewing the sewing parts to the inside. The present invention relates to a seam forming method and apparatus for sewing materials which are used apart from each other.

In the case of sewing as described above by a conventional sewing machine, for example, as shown in FIG. 7, first, the upper fabric W1 and the lower fabric W2 are fitted together, and then the side ends of the upper and lower streams are arranged to cooperate with the needle and the drum. By the upper stitch NS and the lower stitch US with a lactitch seam. Thereafter, as shown in Fig. 9, the upper end W1 and the lower end cloth W2 are separated from each other with the sealing end inward and used.

However, as shown in Figs. 7 and 8, the strength of the fastening force is that the tension between the upper thread NS and the lower thread US, the frictional force at the nodal point between the upper thread NS and the lower thread US, and the outer and inner surfaces of the upper fabric W1 and the lower fabric W2. It is determined by the frictional force generated between the upper thread NS and the lower thread US, the upper fabric W1, and the lower fabric W2. Thus, the strength of the clamping force in these seams all depends on the strength of one thread.

In addition, when the suture breaks apart, the pull of upper thread NS and US, deformation of the nodal point between upper thread NS and lower thread US, compression of upper thread W1 and lower fabric W2 at the contact point of upper thread NS and lower thread US with upper thread W1, lower thread W2 .

Accordingly, when the suture is separated from each other, the contact surface of the suture of the upper fabric W1 and the lower fabric W2 opens, and as shown in FIG. there is a problem.

In addition, it is conceivable to increase the tension between the upper thread NS and the lower thread US while increasing the thickness between the upper thread NS and the lower thread US in order to strengthen the tightening force by the upper thread NS and the lower thread US.

However, in the lock stitch sewing machine, a nodule is formed at the center of the upper fabric and the lower fabric by the balance of the tension between the upper thread NS and the lower thread US, but the means for applying tension to the lower thread US arranged in the bobbin case is a thin plate spring. There is a limit in increasing the tension of the US, and as a result, there is a limit in strengthening the tightening force by the upper thread NS and the lower thread US because a large tension cannot be imparted to the upper thread NS and the lower thread US.

For example, even if the tension is increased with the tension as described above, if an impact is applied to the crack-opened portion, the nodal points of the upper thread NS, the lower thread US, or both appear on the outer surface of the upper fabric W1 and the lower fabric W2 as shown in FIG. there is a problem.

In addition, even if the fastening force is improved by a chain seam by a combination of several threads, such as a double chain stitch or a flat sewing, these chain seams are released therefrom when some of the threads are broken, which causes problems in durability.

In addition, it is conceivable to increase the strength of the fastening force by overlapping the one-sealed part of the seam once with the seam room and resealing it. In addition, there is a problem that it is difficult to insert a needle into the same position of the seam that has been sewn before, so that deformation of the nodal point between the upper thread NS and the lower thread US cannot be prevented.

Also, as shown in Fig. 10, it is conceivable to sew the upper fabric W1 and the lower fabric W2 by hand sewing the two threads HS1 and HS2, but this seam formation takes a lot of time to reduce sewing efficiency and at the same time limit the length of the thread. There are problems such as the inability to form long seams.

1 is a block diagram of a control circuit of the present invention.

2 is a cloth transfer mechanism diagram of a sewing machine as an example of the cloth transfer apparatus of the present invention.

FIG. 3 is an explanatory diagram showing each state of the transfer zero, forward feed and reverse feed in the cloth feed adjusting mechanism shown in FIG. 2; FIG.

4 is a seam of a first embodiment of the present invention.

Fig. 5 is a perspective view of a state where the seam of the cloth sewn with the seam of the present invention is cracked apart.

6 is a control flowchart of an embodiment of the present invention.

7 is a perspective view of a conventional seam.

8 is a cross-sectional view taken along line V-V of FIG.

FIG. 9 is a perspective view of a state in which the sewing material of FIG. 7 is separated from a seam.

10 is a cross-sectional view of another conventional seam.

※ Explanation of symbols about main part of drawing ※

3: Control device (control means) 6: Feed rate setting device

7: Feeding direction setter (cloth feeding device) 11: Feeding direction converter (cloth feeding device)

16: Direct drive motor 29: Cloth feed device

To solve the above conventional problem

The invention of claim 1 uses a sewing machine to form a lactitch to form a plurality of seams by sending the fabric in one direction (n + 1) by a fabric feed device, and then sends n needles in the opposite direction to one direction by the same feed amount. Seam formation method of the sewing machine to form a seam on the fabric by repeating forming a.

According to the invention as set forth in claim 1, the upper and lower stitches sewn by a lactitch seam where the thread is stitched every single needle form a plurality of nodal points at each sewing point, so that the tensile strength of the upper thread NS and the lower thread US is increased. At the same time, the frictional force at the nodal point between the upper thread NS and the lower thread US increases at each sewing point.

In addition, since the upper and lower threads US and the lower thread US span the outer and inner sides of the upper fabric W1 and the lower fabric W2, a large friction force is generated between the upper thread NS and the lower thread US and the upper fabric W1 and the lower fabric W2.

In addition, the strength of the fastening force is dispersed in a plurality of yarns.

When the suture is separated from the above, the pull of the upper thread NS and the lower thread US decreases, and the deformation of the nodal point between the upper thread NS and the lower thread US decreases, and the contact point between the upper thread NS and the lower thread US and the upper fabric W1, the lower fabric W2 The compression of the upper fabric W1 and the lower fabric W2 is also extremely small.

For this reason, it can prevent that the contact surface in the sealing part of the upper fabric W1 and the lower fabric W2 spreads when it separates apart a sealing part. In addition, even if an impact is applied to the gap between the sutures, the upper thread NS, the lower thread US, or both nodules do not appear outside the upper fabric W1 and the lower fabric W2, and thus the product value of the product is improved due to its impact resistance.

In addition, even if a part of the seam is broken, it is a lactitch seam, so there is no loosening at that part.

In addition, in this sewing method, since sewing can be performed continuously, there is an effect that the sewing work efficiency is improved.

In addition, it is possible to insert a needle into the same place of the seam that was previously sealed and to prevent the deformation of the nodal point between the upper thread NS and the lower thread US, thereby improving the quality of the product and improving the product value of the sewing product.

The invention of claim 2 is a seam forming method of a sewing machine in which the needle seam is sewn in one direction after sewing the cloth in one direction in the seam forming method according to claim 1.

The invention of claim 2 can more reliably achieve the effect described in claim 1.

The invention of claim 3 is to form a seam by sending the fabric 2n needles in one direction to the sewing machine for forming a lactitch seam by using a fabric feed device, and then n needles in the opposite direction to the one direction by the same feed amount. Seam forming method of the sewing machine to form a seam on the fabric repeatedly.

According to this invention of Claim 3, the same effect as the invention of Claim 1 can be acquired.

The invention of claim 4 is a seam forming method of a sewing machine in which at least one stitch stitch is formed at each seam in the seam forming method according to claims 1, 2, and 3.

In the invention of claim 4, since a stitch stitch having a strong nodule is formed at each sewing point, the effect of further improving the effect described in claim 1 can be obtained.

The invention of claim 5 is a sewing machine for forming a lactitch seam, a cloth feeding device for sending the cloth in a direction opposite to one direction, and n needles in a direction opposite to the one direction with the same feed amount after sending the cloth feeding device in one direction. It is a seam forming apparatus of the sewing machine of the structure which arrange | positioned the control means which continuously controls a cloth feed apparatus to send.

In the invention of claim 5, the same effects as those described in claim 1 can be obtained.

Next, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

The fabric conveying apparatus 29 shown in FIG. 2 has a structure similar to the fabric conveying mechanism of the conventionally well-known sewing machine in principle. Reference numeral 9 is a main shaft of the sewing machine, reference numeral 10 is an eccentric cam disposed on the main shaft (9).

Reference numeral 11 is a feed amount converter of the cloth, the center portion of which is supported by the shaft 12 so as to be free to rotate on a bed of a sewing machine (not shown). At the left end of the feed rate converter 11, the bases of two links 13 and 14 of the same length are supported to be freely rotatable to the shafts 13A and 14A of the coaxial core, and the tip ends of these links 13 and 14 are free. Are connected by a common shaft 15. These feed amount transducers 11, links 13 and 14, shafts 12 and 14 constitute a feed adjusting mechanism.

Reference numeral 16 denotes a linear motor fixed to a sewing machine frame (not shown), and the actuator 17 and the right end of the feed amount converter 11 are connected to each other so as to be freely rotated by a link 18. Reference numeral 19 is a vertical link, the upper end of which is connected to the eccentric cam 10, and the lower end thereof is freely connected to the shaft 15 at the tip of the links 13 and 14.

Reference numeral 20 is a horizontal feed shaft which is supported on the sewing machine bed (not shown) to be freely rotated, the lower end of the arm 21 protruding upward is fixed to the right end of the horizontal feed shaft 20, and protrudes upward on the left end The lower end of the arm 22 is fixed. Reference numeral 23 is a connecting link, one end of which is connected to the shaft 15 at the tip of the links 13 and 14 so as to be free to rotate, and the other end thereof to be connected to the tip of the arm 22 to be free to rotate. Reference numeral 24 denotes a cloth conveying arm, one end of which is free to rotate at the tip of the arm 22, and the two forked portions 25 of the other end are fitted to the upper and lower cams 27 arranged on the Shanghai coaxial shaft 26 with ease. . Reference numeral 28 is a tooth feed tooth fixed to the cloth feed arm 24.

When the sewing machine is driven and the main shaft 9 rotates, the cloth transfer mechanism 29 moves vertically to the vertical link 19 by the eccentric cam 10, and accordingly, moves a predetermined amount connected to the bottom of the vertical link 19.

The shanghai-dong of this shaft 15 is transmitted to the horizontal feed shaft 20 as follows, and sent to the cloth feed tooth 28 for movement.

That is, when the shafts 13A and 14A are on a straight line H connecting the upper end of the arm 21 and the shaft 15 (FIG. 3A), when the shaft 15 moves up and down by the vertical link 19, the link ( 13) and 14 swing about the axis 13A and 14A, but since the displacement of the upper end of the arm 21 does not cause a horizontal displacement, the tooth transfer gear 28 is stopped and no cloth transfer is performed.

In addition, when the shaft 13A, 14A is upward from the straight line H connecting the upper end of the arm 21 and the shaft 15 (FIG. 3B), the link when the shaft 15 is moved up and down by the vertical link 19 Since the shafts 13 and 14 swing around the shafts 13A and 14A, the shaft 15 connected to the ends of the links 13 and 14 becomes a swing trace as shown in FIG. This causes the displacement of the cloth feed tooth 28 to cause the cloth feed movement in the forward feed direction in a state of protruding from the upper surface of the needle plate (not shown). And the position of the shaft (13A) 14A is moved upward with respect to the straight line connecting the upper end of the arm 21 and the shaft 15, the horizontal displacement amount of the arm 21 increases, the positive feed of the feed tooth 28 The amount of cloth feed in the direction increases.

If the shafts 13A and 14A are below the straight line H connecting the upper end of the arm 21 and the shaft 15 (FIG. 3C), the link is moved when the shaft 15 is moved up and down by the vertical link 19. (13) (14) swings about the axis (13A) (14A), so the axis (15) becomes a swinging trajectory as shown in Figure 3C, so that the horizontal displacement of the reverse phase in the reverse phase as in Figure 3B on the top of the arm (21) This causes the cloth feed tooth 28 to cause the cloth feed movement in the reverse direction while protruding from the upper surface of the needle plate (not shown). And as the positions of the shafts 13A and 14A move downward with respect to the straight line connecting the upper end of the arm 21 and the shaft 15, the amount of cloth transfer in the reverse feed direction increases.

In this way, the direction and the amount of the transfer in the forward and reverse directions are determined by the positions of the shafts 13A and 14A, and the positions of the shafts 13A and 14A at the ends of the links 13 and 14 are linear motors. Controlled by (16).

That is, when the actuator 17 of the linear motor 16 positions the lower end of the link 18 so as to be an intermediate position where the positions of the shafts 13A and 14A are the same as the straight line H, the feed amount as described above. Becomes zero.

When the actuator 17 is lowered so that the position of the lower end of the link 18 is lowered than the intermediate position thereof, the cloth transfer transducer 11 rotates clockwise about the axis 12 and moves to the lowered position of the actuator 17. The positive feed direction and the feed amount are determined by determining the positions of the axes 13A and 14A that are above the straight line H.

In addition, when the actuator 17 of the linear motor 16 raises the position of the lower end of the link 18 from the intermediate position, the transition feed converter 11 rotates counterclockwise about the axis 12. As the positions of the axes 13A and 14A, which are further lower than the straight line H, are determined, the positions of the axes 13A and 14A are thereby determined, and the ascending position of the actuator 17 The feed amount is determined.

In other words, the transfer direction and the transfer amount are determined by the vertical position of the actuator 17 driven by the linear motor 16.

Fig. 1 is a block diagram of a control circuit as a control means in the present invention. Reference numeral 1 is a start stop switch disposed on a foot pedal. When the foot pedal is stepped on, the start signal is generated and the foot pedal is in the original position. A stop signal is generated by returning to. Reference numeral 2 denotes a needle position detector arranged on the main axis of the sewing machine, which detects the needle up and down position to generate a needle position signal, and inputs at least the lower level signal to the control means 3 constituted by ROM, RAM, and CPU, and the CPU It is counted by the internal counter of (not shown). This needle position detector 2 and an internal counter constitute a needle drop frequency detecting means.

In the ROM of the control means 3, a control program including both a function expression and a flow chart to be described later, such as a needle drop number n + 1 for forward feed and a needle drop number n for reverse feed, as described below And the control command so that the forward / backward feed amount and the data about the operation amount (position) of the linear motion motor 16 are stored, and the forward / backward cloth feed amount by the setting of the input means 8 under the control of the CPU. Occurs.

Reference numeral 5 is a sewing machine motor for driving and stopping the sewing machine, 4 is a driving circuit for driving and stopping the sewing machine motor 5, 6 is a driving circuit for driving and stopping the linear motor 16, and 7 is a linear motor 16 The control circuit controls the drive circuit 6 so that the operation position of the control position becomes the command position from the control means 3.

Reference numeral 8 denotes an input means for designating a seam method according to the present invention, which is input by the operator to the control means 3 by setting the needle drop number n or the forward feed amount for reverse feed.

Alternatively, the forward feed needle drop number and the reverse feed needle drop number may be set separately.

In addition, a pattern in which the number of forward seams and the number of reverse seams are set in advance may be stored in a ROM of the control means 3 or the like.

Next, the operation of the first embodiment of the present invention will be described. The first embodiment is an example of the case of (n + 1) needle drop in the forward direction and n needle drop in the reverse direction.

And the first embodiment is the case of n = 1.

First, n = 1 is input by the input means 8 by the input setting subroutine as the data of the needle drop count (S-1).

Next, the control circuit 7 is instructed to drive the drive amount corresponding to the input constant feed amount set by the drive circuit 6 to drive the linear motion motor 16 (S-1). As a result, the actuator 17 is lowered to set the predetermined feed amount in the forward direction.

Next, when the pedal is depressed and a start signal is generated from the start switch 1 (S-3), the sewing machine motor 5 is driven by the drive circuit 4 (S-4), and the sewing machine starts to form a seam. do. As long as the counter inside the control means 3 counts the needle position signal from the needle position detector 2, and the pedal is opened and the stop signal does not occur (S-5), the second needle drop is made. The counter counts n ₀ = n + 1. That is, the actuator 17 of the linear motor 16 is held in the lowered position until the next needle drop is performed after the first needle drop is performed in the forward direction.

Thereafter, the control circuit 7 is instructed to drive the drive amount corresponding to the input reverse feed amount, and the linear motion motor 16 is driven by the drive circuit 6 (S-7). As a result, the actuator 17 is raised and set in the reverse transfer direction of the transfer amount such as the forward direction.

When the counter counts n ₀ = 1 by the signal from the next needle position detector 2 (S-8), the linear motor 16 is driven to set the positive feed amount (S-9). Until the stop signal is input (S-5), the operation is performed in which the next needle drop is the reverse cloth transfer after the forward needle feed is performed between the two needle drops.

In other words, two needle drops are sent in the forward direction, and then the fabric is sent in the reverse direction with the same amount of cloth feed as the forward direction, and then one needle drop is repeatedly performed, thereby forming a duplicate seam.

Next, the actual seam formation state is demonstrated in FIG.

In the seam shown in Fig. 4, the upper thread NS1, NS2, NS3 and the lower thread US1, US2, US3 fall up and down with respect to the upper and lower surfaces of the upper fabric W1 and the lower fabric W2, but are actually strongly threaded every needle. Therefore, these upper and lower threads closely adhere to the upper and lower surfaces of the upper fabric W1 and the lower fabric W2.

The linear motor 16 is driven at the lowered position corresponding to the forward feed amount P. As shown in FIG. When the sewing machine motor 5 is driven, the needle first falls to the sewing point A of FIG. 4 to form the nodule 1A of the perfect stitch, and then the upper fabric W1 and the lower fabric W2 are sent by the feed amount P in the positive feed direction in the direction of the arrow X. This suture point B falls to form the nodule 2A of the perfect stitch.

The two needle drop times are counted by the counter (n ₀ = n + 1) and set to n = 1, so that n ₀ = 2, and from the control circuit 7 by the command from the control means 3 When the signal is generated, the actuator 17 of the linear motion motor 16 is in the ascending position corresponding to the reverse feed amount P equal to the forward feed amount, and the upper fabric W1 and the cloth fabric W2 are sent by the feed amount P in the reverse feed direction in the direction of the arrow Y, so that the needle Drop to suture point A to form a nodule 3A of the stitch stitch.

When the needle drop number n ₀ = 1 is counted at the sewing point A after the reverse feed, the actuator 17 of the linear motion motor 16 is set to the lowering position as the initial position, and is set to the forward feed amount P, and the upper fabric W1 and the lower fabric W2 is sent by the feed amount P in the positive feed direction in the direction of the arrow X, and the fourth needle drop is made at the sewing point B to form the nodule 4A of the perfect stitch. In addition, the upper fabric W1 and the lower fabric W2 are sent by the feed amount P in the positive feed direction, and the fifth drop of the needle is performed at the suture point C to form the nodule 5A of the perfect stitch.

When the number of needle drop times in the forward direction is counted by the counter, the actuator 17 of the linear motion motor 16 becomes the same upper position as the previous time and is reversed, and the upper fabric W1 and the lower fabric W2 are reversed in the direction of the arrow Y. The needle drop of the sixth time is sent to the sewing point B to form the nodule 4 of the quench stitch in the feeding direction.

Thus, in the formed seam, two perfect stitches and a single stitch stitch with strong nodular force are formed at one suture point (same needle drop position), such as suture point B and suture point C of FIG. In addition, three upper threads NS1, NS2, NS3, and lower threads US1, US2, and US3 exist between the pitches of the seams, respectively, and the frictional force at the contact surface between the upper thread and the upper fabric W1 and the lower thread and the lower fabric W2 is increased.

Since the seam is sealed by such a seam, even if the seam is opened apart as shown in Fig. 5, the contact surfaces at the seams of the upper fabric W1 and the lower fabric W2 do not open.

Although the first fixed sewing was not performed in the first embodiment, the first fixed sewing may be performed by an operator's operation signal.

For example, as fixed sewing at the start of sewing, send the same feed amount (pitch) in the reverse direction (X direction), and then form a seam by dropping the needle at the fixed sewing point, and then form a seam at the feed stitch A with the same pitch in the forward direction, and It is then sent back to the same pitch in the reverse direction to form a seam at the fixed suture point. The seam of the first embodiment is formed after the first fixed sewing is finished.

Moreover, you may make fixed sewing of the sewing finish complete.

In addition, the first fixed sewing and the last fixed sewing can be executed automatically by a signal input to the sewing machine control device, for example, a start signal and an end signal of the pedal that are set when the foot switch is set.

The needle drop count (seam count) of seam formation by forward feed and the needle drop count (seam count) of seam formation by reverse feed can be arbitrarily changed as shown in the above embodiment. For example, four needle drops may be performed by forward feed, followed by two needle drops by reverse feed. Accordingly, after the third needle drop, two perfect stitches and one quench stitch are formed at each needle drop point.

In addition, in each of the above-described embodiments, the needle drop number closed in the forward feed is higher than the needle drop number closed in the reverse feed. However, the needle drop frequency closed in the reverse feed is closed in the forward feed. The number of needle drops may be higher than that.

In addition, in the actual sewing machine, even if the feed rate is set to the same feed amount in the forward feed and the reverse feed, the actual feed amount may be precisely different, but it is almost the same needle dropping point, and can be said to be substantially the same needle dropping point.

Moreover, although the above-mentioned embodiment demonstrated the structure which sends upper fabric and side cloth by the cloth transfer mechanism of a sewing machine as a cloth transfer apparatus, this cloth transfer apparatus may be changed to the well-known X-Y transfer apparatus. Accordingly, the straight seam can be formed continuously in any shape seam such as a curved seam or a seam where the curve and the straight line are continuous.

In addition, the nodule of the upper thread NS and the lower thread US at each suture point can form a stitch stitch arbitrarily by controlling the upper thread NS, the lower thread US, the needle, or the like.

In particular, when the stitch stitch is not required, a well-known stitch stitch preventing mechanism, for example, a mechanism for rotating the needle bar and the drum in the axial direction to prevent seam formation in the region of the stitch stitch forming transfer direction, may be used. It is also possible to prevent the formation of the quench stitch at the suture point.

As described above, in the present invention, the upper fabric and the lower fabric stitched by the stitches of thread stitches every needle are formed with a plurality of nodal points at each needle drop point (sewing point), so that the tensile strength of the upper thread NS and the lower thread US is increased. At the same time, the frictional force at the nodal point between the upper thread NS and the lower thread US at each sewing point is also increased.

In addition, since the upper and lower thread US and the lower thread US span the outer and inner sides of the upper fabric W1 and the lower fabric W2, a large frictional force is generated between the upper thread NS and the lower thread US and the upper fabric W1 and the lower fabric W2.

In addition, the strength of the fastening force is dispersed in a plurality of yarns.

When the suture is separated from the above, the extension of the upper thread NS and the lower thread US decreases, and the deformation of the nodal point between the upper thread NS and the lower thread US decreases, and also in the contact portion between the upper thread NS and the lower thread US, the upper fabric W1, and the lower fabric W2. The compression of the upper fabric W1 and the lower fabric W2 is also extremely small.

Accordingly, in the present invention, it is possible to prevent the contact surface from the suture of the upper fabric W1, the lower fabric W2 when the suture is separated, and the nodal points between the upper thread NS, the lower thread US, or both appear on the outer fabric of the upper fabric W1, the lower fabric W2. As a result, the product value of the product is improved, and even if an impact is applied to the part that separates the sutures, the nodal points between the upper thread NS and the lower thread US do not appear on the upper fabric W1 and the lower fabric W2. have.

In addition, even if a part of the seam is broken, it is a lock stitched seam, so it is not loosened at that part, so it has excellent durability.

In addition, in this sewing method, since sewing can be performed continuously, there is an effect that the sewing work efficiency is improved.

In addition, the needle can be inserted in the same position as the needle drop point at the same time, and the deformation of the nodal point between the upper thread NS and the lower thread US can be prevented, thereby improving the product quality and improving the product value of the sewing product. have.

Moreover, since the stitch stitch which has a strong nodular force is formed in each suture point, the effect which further improves the effect described above can be acquired.

Claims (5)

For the sewing machine forming the lactitch, the fabric is sent by (n + 1) needles in one direction by the fabric feeder to form several seams, and then the needles are repeatedly sent in the opposite direction to one direction by the same feed amount to form the seams. Seam forming method of a sewing machine, characterized in that the seam is continuously formed on the cloth. The method of claim 1, Seam forming method of a sewing machine, characterized in that the seam is continuously formed on the cloth by sewing the needle in two directions in one direction and then sewing the needle in the opposite direction to one direction. For the sewing machine that forms the lactitch, the fabric is sent by 2n needles in one direction by a cloth feeder to form multiple seams, and then the n seams are sent in the opposite direction to one direction by the same feed to form seams. Seam forming method of a sewing machine, characterized in that the continuous forming. The method according to claim 1, 2, 3, A seam forming method for a sewing machine, characterized in that at least one stitch stitch is formed at each suture point. A sewing machine for forming a lactitch seam, a fabric feeder for sending the fabric in a direction opposite to one direction, and a fabric feeder for sending n needles in the opposite direction to the one direction by the same feed amount after the needle is sent in one direction (n + 1). Seam forming apparatus for a sewing machine, characterized in that the control means for continuously controlling the transfer device arranged.