JP2022090582A - Lock stitch sewing machine having sewing thread control function - Google Patents

Abstract

To provide a sewing machine achieving a stable and moderate sewing force and stable repetition of a stitch shape suitable for a sewn product with respect to a seam quality of the sewn product.SOLUTION: A sewing machine controls stability of a sewing force and a stitch shape by detecting thickness of a sewn material such as cloth without completely relying on "miraculous balance based on empirical rule" depending on friction force, controlling amount (length) of a needle thread used for one stitch calculated from the thickness and movement amount of the sewn material; that is, feed amount of the sewing machine, forcibly reeling out the amount of needle thread, further detecting the thickness of the sewn material such as cloth, controlling amount (length) of a tightening bobbin thread of one stitch calculated from the thickness, and tightening the amount of the bobbin thread; in other words, by directly or indirectly calculating thread amount of the sewing thread consumed for one stitch and controlling the amount.SELECTED DRAWING: Figure 1

Description

It is a technique related to the structure of a sewing machine and sewing technology.

Problems to be solved by the present invention

For the seam quality of the sewn product, stable and appropriate suturing force and stable repetition of the first stitch morphology suitable for the sewn product are major evaluation requirements.

However, in the "current general" mechanism and process of seam formation and stitch force generation "(hereinafter referred to as" conventional method "), the sewing quality of the sewn product is as follows: sewing thread and cloth (sewing machine), sewing thread. It is based on the rule of thumb that the balance of frictional force between sewing thread and sewing thread and sewing machine parts is used better as it is closer to "miracle".

It is difficult to control the frictional force, and it is difficult to adjust the sewing machine in order to obtain a stable and appropriate stitching force and a stable repetition of the first stitch morphology suitable for the sewn product.

In order to solve such current problems, stable quality is achieved by controlling the amount of thread consumed in the first stitch without relying on the "miracle balance based on empirical rules" that depends on the frictional force. According to the present invention, the present invention relates to Japanese Patent Application No. 2020-66285 "seam stable bobbin thread control device" and Japanese Patent Application No. 2020-117384 "seam stable bobbin thread control device" for controlling the needle thread. Is presented as Japanese Patent Application No. 2020-199883 "Lockstitch sewing machine having a needle thread forced supply function".

However, in each case, the error between the calculated thread amount and the thread amount that should actually be used for the stitch is complemented by the frictional force of the bobbin thread if it is a needle thread and the needle thread if it is a bobbin thread. ing.

Means to solve problems

In the present invention, by using the needle thread control and the bobbin thread control of the above invention in combination, the thickness of the sewn object such as cloth can be adjusted without completely relying on the "miracle balance based on the empirical rule" depending on the frictional force. It detects and controls the amount (length) of the needle thread used for the first stitch calculated from the thickness and the movement amount of the sewing material, that is, the feed amount of the sewing machine, and forcibly feeds the needle thread amount. Further, by detecting the thickness of the sewn object such as cloth, controlling the bobbin thread tightening amount (length) of the first stitch calculated from the thickness, and tightening the bobbin thread amount, that is, it is consumed in the first stitch. By directly or indirectly calculating the thread amount of the sewing thread to be formed and controlling the amount, the stitching force and the stability of the stitch morphology are controlled.

Effect of the invention

By sewing using the lockstitch sewing machine having the sewing thread control function of the present invention, it is possible to realize a stable and appropriate suturing force and stable repetition of the first stitch form suitable for the sewn product. Good seam quality can be obtained.

Detailed description of the invention

First, the "conventional" seam forming process will be described using the modeled motion diagram of FIG.

The seam forming process starts from the top dead center phase (phase 1) of the balance, and the supply of the needle thread 13 inside the mechanism is started. After that, the required amount of the upper thread of the kettle is generated from the phase (phase 2) in which the thread hole of the needle passes through the needle plate (actually the sewn object), and the upper thread loop capture phase (phase 4) of the tip of the kettle sword and the upper thread. After passing through the loop through the phase (phase 8) in which the bobbin (bobbin thread storage portion) passes through, the balance rises from the balance bottom dead point phase (phase 7), and the needle thread 13 released in phase 8 begins to be collected. , The feed start phase (phase 6 = feed dog comes out to the upper surface of the needle plate), the needle thread 13 is tightened again at the balance top dead point phase (phase 1'), and the bobbin thread tightening phase (phase 9). The final stitch (bobbin thread) is tightened in, and the formation of the first stitch is completed.

In the motion diagram of FIG. 1, the feed end phase (phase 10 = feed dog sinks into the lower surface of the needle plate) comes after the bobbin thread tightening phase (phase 9), which is the bobbin thread 14 (upper thread). In order to prevent the sewn cloth and sewing thread from being pulled back by the tightening of 13), if the peak of the horizontal feed amount has passed at the time of the bobbin thread tightening phase (phase 9), the feed amount is the seam in this phase. It does not affect the morphology.

FIG. 2 and FIGS. Shown in 3.

Therefore, the "behavior of the needle thread 13 and the bobbin thread 14 accompanying the seam forming process" will be followed by using the motion diagram of FIG. 1 as an example.

The behavior of the needle thread 13 accompanying the seam forming process starts from the balance top dead center (phase 1) at which the needle thread supply (balance needle thread supply amount curve) to the mechanism in the sewing machine mechanism starts, and this phase is the stitch forming cycle. It becomes the starting point of. Next, absorption of the required upper thread of the mechanism (required curve of the upper thread of the hook) starts from the phase 2. The difference between the balance needle thread supply amount and the hook needle thread required amount in each phase is the "sag" of the needle thread 13, and this "slack" is absorbed by the thread take-up spring 17.

When the phase advances and the needle bar bottom dead point (phase 3) is passed, the required amount of the upper thread of the kettle continues to decrease as the needle rises, and the supply amount of the upper thread of the balance continues to increase, so that the "sag" continues to increase and the kettle continues to increase. In the needle thread loop capture phase (phase 4) of the sword tip, "sag" actually occurs beyond the absorption capacity limit of the thread take-up spring 17 (absorption capacity limit of the thread take-up spring stroke). The "sag" is a needle thread loop for the tip of the hook to catch.

After passing the needle thread loop capture phase (phase 4) at the tip of the hook sword, the required amount of hook needle thread starts to increase again, and the difference between the balance needle thread supply amount and the hook needle thread required amount is within the absorption capacity of the thread take-up spring 17. .. When the bobbin (bottom thread storage portion) slips through the loop of the needle thread 13 (phase 8), the needle thread 13 is released from the tip of the hook sword and decreases at once.

Further, the supply amount of the balance needle thread also decreases at once when the balance bottom dead center (phase 7) is passed. This decrease in the supply amount of the needle thread of the balance plays a role of pulling the needle thread 13 released from the tip of the hook sword to the upper surface of the cloth (sewing material).

Further, before and after such a phenomenon, the feed dog appears on the upper surface of the needle plate (phase 6), and the horizontal feed functions to feed (move) the sewing material and consume the needle thread 13. ..

FIG. 2 shows the seam form and the state of the sewing thread (upper thread 13, bobbin thread 14) of the phase (phase 1') at which the phase is further advanced and the balance top dead center is reached again.

Between phase 1 and phase 1', the amount of needle thread (thread amount from 21 to 22) that was used for feed and seam formation and was insufficient is from the balance bottom dead point (phase 7) to the balance top dead point (phase 1). In the process of tightening (recovering) the needle thread toward'), it is pulled out from the needle thread tensioner (direction 18) against the needle thread tension pressure. At this time, a stable and appropriate suture force affected by the needle thread tension pressure is generated at the seam.

The phase further advances, and in the bobbin thread tightening phase (phase 9), the needle thread 13 is pulled back into the cloth (seed) by the bobbin thread 14 to complete the seam form as shown in FIG.

That is, the stitch forming cycle of the "conventional method" starts from the top dead center of the balance (phase 1) and is completed at the final stitch (bob thread) tightening phase (phase 9) of about 400 °.

Next, the behavior of the bobbin thread 14 accompanying the seam forming process will be described.
The behavior of the bobbin thread 14 begins with the bobbin thread tightening phase (phase 9') of the previous seam. In this phase 9', the bobbin thread path is longer than the normal bobbin thread path by the bobbin thread tightening amount 12 in the motion diagram of FIG. 1 due to the cam surface 24 of the hook or the bobbin thread feeding lever. It has become.

Therefore, when the bobbin thread tightening phase (phase 9') is passed and the normal thread path is returned, the bobbin thread amount of the bobbin thread tightening amount 12 becomes "sag of the bobbin thread 14."

This "sag of bobbin thread 14" is consumed by "feeding the sewing material" or "entanglement with the needle thread 13", but the second "kama" (because the hook makes two rotations during 360 °). Since "feeding of the sewn material" and "entanglement with the needle thread 13" do not occur until the phase (phase 5) at which the "cam surface" 24 provided on the bobbin thread path comes to the bobbin thread path, the "bobbin thread""14slacks" are not consumed. That is, there is no tightening and feeding of the bobbin thread 14 in the phase (phase 5) when the second "cam surface provided in the hook" 24 comes to the bobbin thread path path. Also, in the bobbin thread feeding lever method, the movement of the bobbin thread feeding lever is independent of the movement of the hook, so that "the second" cam surface provided on the hook "comes to the bobbin thread path". There is no movement.
That is, in any of the methods, the behavior of tightening and feeding the bobbin thread 14 at the phase 5 on the motion diagram of FIG. 1 does not occur.

This "sag amount of bobbin thread 14" is sequentially consumed from the feed start phase (phase 6) of the sewing material as the feed amount increases, and the needle thread is consumed at the tightening phase of the needle thread (balance top dead point (phase 1')). It is raised to 13 and consumed. However, the amount of bobbin thread consumed by "feeding the sewing material" and "tightening the needle thread" is much larger than that of "the amount of slack in the bobbin thread 14", and is consumed after the "sag amount" is exhausted. As the (phase) advances, the bobbin thread 14 is slowly pulled out from the bobbin (bobbin thread storage portion) against the bobbin thread tension spring.

As a result, the bobbin thread 14 in the balance top dead center phase (phase 1') has the form shown in FIG. 2, and then in the bobbin thread tightening phase (phase 9), the bobbin thread 14 is tightened as shown in FIG. The seam form (20 to 23) is completed.

FIG. 4 shows an example in which the state of the bobbin thread 14 in the bobbin thread tightening phase (phase 9) is set to the cam surface 24 of the hook as the tightening mechanism. Further, FIG. 5 shows an explanatory diagram of the change in the stitch morphology of the transition from the balance top dead center phase (phase 1') to the bobbin thread tightening phase (phase 9).

The bobbin thread tightening phase (phase 9) in which the bobbin thread 14 of the range 25 shown by the broken line in the above figure, which is the seam form at the balance top dead point phase (phase 1'), is finally tightened and the stitch formation is completed. Although the stitch form in FIG. 5 is shown in the lower figure of FIG. 5, the "final stitch (bobbin thread) tightening amount" is not theoretically quantified, and the sewing quality of the sewn object is the sewing thread and the cloth (sewing). It relies on the frictional force of the needle thread and bobbin thread, the sewing thread and the peripheral members, and is secured by the "miracle balance based on the empirical rule" of the frictional force.

That is, since the "final stitch (bobbin thread) tightening amount" changes depending on the thickness of the object to be sewn, the bobbin thread tightening amount 12 in the bobbin thread tightening phase (phases 9 and 9') of the motion diagram of FIG. The bobbin thread amount is designed to be larger than the actual "final stitch (bobbin thread) tightening amount", and the "final stitch (bobbin thread)" consumed by the "miracle balance based on the empirical rule" of the frictional force. The "tightening bobbin thread amount", which is larger than the "tightening amount", is pulled out from the bobbin (bobbin thread storage portion) against the bobbin thread tension spring pressure.

From the seam forming process and the behavior of the needle thread 13 and the bobbin thread 14 as described above, a stable and appropriate suture force of the seam and a stable repetition of the first stitch form suitable for the sewn product can be obtained for the sewing thread and the cloth (sewing). It can be seen that the closer to the "miracle" the balance of the frictional force between the sewing thread and the sewing thread, and the sewing thread and the sewing machine parts, the better the rule of thumb is used.

However, it is difficult to control the frictional force, and it is difficult to adjust the sewing machine to obtain a stable and appropriate suture force and a stable repetition of the first stitch shape suitable for the sewn product. The thickness of the sewn material such as cloth is detected without completely relying on the "miracle balance based on the empirical rule" that depends on the frictional force, and it is calculated from the thickness and the movement amount of the sewn material, that is, the feed amount of the sewing machine. The amount (length) of the needle thread used in the first stitch is controlled, the needle thread amount is forcibly fed out, and the thickness of the sewn object such as cloth is similarly detected and calculated from the thickness. By controlling the bobbin thread tightening amount (length) of the first stitch and tightening the bobbin thread amount, that is, the thread amount of the sewing thread (upper thread 13 and bobbin thread 14) consumed in the first stitch is directly adjusted. Alternatively, it is intended to indirectly control the stitching force and the stability of the stitch morphology by indirectly calculating and controlling the amount.

Based on the motion diagram modeled in FIG. 1, the seam forming cycle and the seam morphology cycle will be described again.
The "conventional method" stitch forming cycle starts from the balance top dead point phase (phase 1), the supply of the needle thread 13 inside the mechanism is started, and then the thread hole of the needle is the needle plate (actually, the sewn object). ), The required amount of the upper thread of the kettle is generated from the phase (phase 2), and the upper thread loop capture phase (phase 4) of the tip of the kettle and the phase (phase 8) through which the bobbin (bobbin thread storage portion) passes through the upper thread loop. ), The needle thread 13 released in phase 8 is started to be collected by raising the balance from the balance bottom dead point phase (phase 7), and further, the feed start phase (phase 6 = feed dog comes out to the upper surface of the needle plate). After that, the needle thread 13 is tightened again in the balance top dead point phase (phase 1'), and the final stitch (bobbin thread) is tightened in the bobbin thread tightening phase (phase 9) to form the first stitch. It is a cycle of about 400 ° to finish.

On the other hand, as shown in FIG. 6, in the stitch form cycle 26, the next same stitch is started from the bobbin thread tightening phase (phase 9') of the stitch form in which the knot points of the upper and lower threads are positioned in the thickness of the sewing material. It is a 360 ° cycle up to the bobbin thread tightening phase (phase 9) showing the morphology.

In the present invention, the phase of each process is substantially the same as that of the "conventional method" except that the starting point of the stitch forming cycle is the bobbin thread tightening phase (phase 9'). That is, the seam forming cycle has exactly the same phase as the seam form cycle, "from the bobbin thread tightening phase (phase 9') of the stitch form in which the knot points of the upper and lower threads are positioned in the thickness of the sewing material, the next The cycle is 360 ° up to the bobbin thread tightening phase (phase 9) showing the same stitch form.

As shown in FIG. 7, in the bobbin thread tightening phase (phase 9'), this is a seam and a thread supply section (a thread feeder (18 direction) for the needle thread 13 and a bobbin thread storage section for the bobbin thread 14). This is possible by putting the sewing thread (upper thread and bobbin thread) between the bobbin)) into a tense state.

After the bobbin thread tightening phase (phase 9'), which is the end point of the previous seam forming cycle, a new seam forming cycle starting from the bobbin thread tightening phase (phase 9') starts, and the thickness of the sewn material such as cloth starts. Is detected, and the amount (length) of the needle thread used in the first stitch calculated from the thickness and the movement amount of the sewing machine, that is, the feed amount of the sewing machine, etc., is calculated as the balance top blind point phase (phase 1'). In the phase between and, the needle thread feeder (18 directions) sequentially forcibly supplies the yarn. Ideally, the amount of thread that makes the needle thread loop appropriate and stable in size for the pot sword tip to capture between the bobbin thread tightening phase (phase 9') and the needle thread loop capture phase (phase 4) of the pot sword tip. However, it is desirable that the remaining yarn amount is supplied between the balance bottom dead point phase (phase 7) and the balance top dead point phase (phase 1').

FIG. 8 shows the seam form of the balance top dead center phase (phases 1 and 1') and the state of the sewing thread (upper thread 13 and bobbin thread 14) near the seam. FIG. 8 shows the same morphology as that of FIG. 2 in which the seam morphology at the balance top dead center phase of the “conventional method” and the sewing thread (upper thread 13 and bobbin thread 14) in the vicinity of the stitch are in the same morphology as in FIG. It can be seen that the needle thread 13 is tightened in the phase (phase 1'and 1).

The forcibly supplied "amount (length) of the needle thread consumed in one stitch" is from 20 when the end point phase (bobbin thread tightening phase (phases 9 and 9')) in FIG. 7 is reached. It is consumed by the needle thread length of 23.

FIG. 8 shows the stitch morphology and the state of the sewing thread of the balance top dead point phase (phases 1'and 1) in the middle of the stitch forming cycle. The start point (end point) phase (FIG. 7) and the balance top dead point phase. The length of the needle thread "15 to the length of the balance thread hole 16 to 18" is significantly different from that of (FIG. 8), and the tightening tension of the needle thread is also generated and transmitted to the needle thread of 20 to 15 due to this difference. .. The relationship between the upper thread length of the end point (start point) phase (FIG. 7) and the balance top dead point phase (FIG. 8) in the middle of the stitch formation cycle is basically (20 to 23 to 15 to 19 in FIG. 7). (Length of balance thread holes 16 to 18 at the position of) = (lengths of balance thread holes 16 to 18 from 20 to 15 in FIG. 8).

布（被縫製物）の変形、及び、該張力による上糸１３の伸縮により吸収される。At this time, "the thickness of the sewn object such as cloth is detected, and the thickness and the amount of movement of the sewn object, that is, the sewing machine.

It is absorbed by the deformation of the cloth (sewing material) and the expansion and contraction of the needle thread 13 due to the tension.

Further, since the length of the needle thread from 20 to 15 differs depending on the thickness of the object to be sewn and the feed amount generated from the balance top dead point phase (phase 1') to the bobbin thread tightening phase (phase 9), the end point (end point (phase 1'). The end point phase (bobbin thread tightening phase (phase) corresponding to the change in the difference in the needle thread length from 20 to 15 between the start point) phase (FIG. 7) and the balance top dead point phase (FIG. 8) in the middle of the stitch formation cycle. 9 and 9')) The needle thread path length between 15 and 18 in FIG. 7 must be changed.

This can be dealt with by changing the position 19 of the balance thread hole 16. That is, the correspondence can be taken by changing the phase of the end point phase (bobbin thread tightening phase (phases 9 and 9') corresponding to the detected thickness of the sewing material.

On the other hand, the behavior of the bobbin thread 14 also starts from the bobbin thread tightening phase (phase 9') of the previous seam. I will explain using "Explanatory diagram".

In the bobbin thread tightening phase (phase 9'), which is the starting point of the seam forming cycle, the bobbin thread path is set to the bobbin thread tightening amount of the previous seam by the action while the stitch stable bobbin thread control member 27 is operating. The bobbin thread amount (b + c-a) is longer than the normal bobbin thread path.

Therefore, when the bobbin thread tightening phase (phase 9') is passed and the normal thread path is returned, the bobbin thread amount corresponding to the bobbin thread tightening amount of the previous stitch becomes "sag of the bobbin thread 14."

This "sag amount of bobbin thread 14" is sequentially consumed from the feed start phase (phase 6) of the sewn object as the feed amount increases, and the needle thread is consumed at the tightening phase of the needle thread (balance top dead point (phase 1')). It is raised to 13 and consumed. However, the amount of bobbin thread consumed by "feeding the sewing material" and "tightening the needle thread" is much larger than that of "the amount of slack in the bobbin thread 14", and after the "sag amount" is exhausted. As the consumption (phase) progresses, the bobbin thread 14 is slowly pulled out from the bobbin (bobbin thread storage portion) against the bobbin thread tension spring.

As a result, the bobbin thread 14 in the balance top dead center phase (phase 1') has the form shown in FIG. 8, and then in the bobbin thread tightening phase (phase 9), the bobbin thread 14 is tightened as shown in FIG. The seam form (20 to 23) is completed.

In the "conventional method", the "final stitch (bob thread) tightening amount" is not theoretically quantified, and the sewing quality is as follows: sewing thread and cloth (sewing), needle thread and bobbin thread, sewing thread and peripherals. It relies on the frictional force of the member and is ensured by the "miracle balance based on the rule of thumb" of the frictional force.

INDUSTRIAL APPLICABILITY The present invention stably improves sewing quality by quantifying the "final stitch (bobbin thread) tightening amount" and controlling the amount, and the method thereof will be described with reference to FIGS. 9 and 5. do.

FIG. 5 is also an explanatory diagram showing a state change of the sewing thread (upper thread 13 and bobbin thread 14) from the balance top dead center phase (FIG. 8) to the bobbin thread tightening phase (seam forming cycle end point phase (FIG. 7)). .. In the bobbin thread tightening phase, the bobbin thread 14 in the range 25 indicated by the broken line in the upper figure of FIG. The height 28 from the upper surface 30 of the needle plate of the presser 29 can be detected by using a differential transformer or the like. The bobbin thread tightening amount detected and calculated in this way is tightened by the method of FIG. 9 “Explanatory drawing of the basic form of the bobbin thread tightening function”.

In FIG. 9, since the distance a between the bobbin thread supply side thread path member 31 and the sewing material side thread path member 32 is always fixed and maintained at a constant value, the movement of the stitch stable bobbin thread control member 27 is controlled. By doing so, the amount of change in the amount of yarn between the yarn path members 31 and 32 b + c—a can be accurately obtained. That is, from the viewpoint of the stitch form cycle, by accurately tightening the extra bobbin thread amount, the bobbin thread amount required for the first stitch is accurately supplied.

This amount of change b + c-a corresponds to the amount of bobbin thread spent in the range 25 indicated by the broken line in the upper figure of FIG. 5 calculated by the height 28 from the needle plate upper surface 30 of the presser 29. Therefore, when the bobbin thread 14 is supplied from the thread supply side to the change amount b + ca of the thread amount between the thread path members 31 and 32, "(change amount b + ca of the thread amount between the thread path members 31 and 32). = (Amount of bobbin thread spent in the range 25 shown by the broken line in the upper figure of FIG. 5) ”does not hold, that is, the knot position of the upper and lower threads varies, the stitches are not stable, and the sewing quality deteriorates. In the tightening phase, the thread holding operating member 33 operates, fixes the bobbin thread 14, and cuts off the bobbin thread supply from the bobbin thread supply side.

より生ずる布（被縫製物）の変形、及び、該張力による下糸１４の伸縮により吸収される。In such a bobbin thread control process, the bobbin thread is calculated by detecting the thickness of the cloth (sewing material).

It is absorbed by the deformation of the cloth (seed) and the expansion and contraction of the bobbin thread 14 due to the tension.

を制御できることとなる。すなわち、布の厚み方向で消費される縫い糸の総量をＬとす

Will be able to be controlled. That is, let L be the total amount of sewing thread consumed in the thickness direction of the cloth.

The "seam crossing rate" is a numerical value indicating the percentage of the thickness of the sewn object when the knot point of the needle thread and the bobbin thread is viewed from the upper thread side of the sewn object, and the standard has been described so far. Although it is 50%, it is generally said that the "seam crossing rate of 60%" has a good "beauty" when the seam of the sewing material is seen from the needle thread side and does not affect the stitching force. It has been.

FIG. 1 is a motion diagram modeling the movement of a general sewing machine mechanism and the behavior of sewing threads (upper thread 13 and lower thread 14). FIG. 2 is a diagram showing a seam form of the balance top dead center phase (phases 1 and 1') of the "conventional method" and a state of the sewing thread (upper thread 13 and bobbin thread 14) in the vicinity of the seam. FIG. 3 is a diagram showing a stitch form of the bobbin thread tightening phase (phases 9 and 9') of the "conventional method" and a state of the sewing thread (upper thread 13 and bobbin thread 14) in the vicinity of the stitch. FIG. 4 is an explanatory diagram showing the state of the bobbin thread 14 in the bobbin thread tightening phase (phase 9) by using the tightening mechanism as the cam surface of the hook. FIG. 5 is an explanatory diagram of a change in the seam morphology of the transition from the balance top dead center phase (phase 1') to the bobbin thread tightening phase (phase 9). FIG. 6 is an explanatory diagram of a seam morphology cycle. FIG. 7 is a diagram showing a stitch form of the bobbin thread tightening phase (phases 9 and 9') of the present invention and a state of the sewing thread (upper thread 13 and bobbin thread 14) in the vicinity of the stitch. FIG. 8 is a diagram showing the seam form of the balance top dead center phase (phases 1 and 1') of the present invention and the state of the sewing thread (upper thread 13 and bobbin thread 14) in the vicinity of the seam. FIG. 9 is an explanatory diagram of a basic form of the bobbin thread tightening function.

1 and 1'... the top dead point phase of the balance, 2 ... the phase in which the thread hole of the needle passes through the needle plate (actually the sewn object), 3 ... the bottom dead point phase of the needle bar, 4.・ ・ Upper thread loop capture phase at the tip of the kettle sword, 5 ... The phase at which the second "cam surface provided in the kettle" comes to the bobbin thread path, 6 ... The feed start phase (feeder) Phase appearing on the upper surface of the needle plate), 7 ... Phase of the bottom dead point of the balance, 8 ... Phase of the bobbin (bobbin thread storage portion) passing through the needle thread loop, 9 and 9'... Bobbin thread tightening phase. 10, ... Feed end phase (phase in which the feed dog sinks into the lower surface of the needle plate), 11 ... Horizontal feed amount, 12 ... Bobbin thread tightening amount, 13 ... Upper thread, 14 ... Bobbin thread, 15 ... Contact point between needle thread and presser, 16 ... Balance thread hole, 17 ... Thread picking spring, 18 ... Direction to needle thread tensioner (thread feeder), 19. .. Balance thread hole position in bobbin thread tightening phase (phases 9 and 9)', 20 ... 1 stitch before stitch, 21 ... 22 position of stitch 1 stitch before, 22 ... on balance Needle thread reference position in dead point phase, 23 ... new stitch position, 24 ... cam surface provided in the kettle, 25 ... range of bobbin thread 14 tightened in bobbin thread tightening phase, 26 ... 1 stitch form cycle (1 stitch length), 27 ... stitch stable bobbin thread control member, 28 ... thickness of cloth (seed) (height from needle plate upper surface 30 on the lower surface of presser 29) S), 29 ... presser, 30 ... needle plate upper surface, 31 ... bobbin thread supply side thread path member, 32 ... sewing material side thread path member, 33 ... thread holding operating member

Claims (3)

The thickness (length) of the needle thread used for the first stitch calculated from the thickness of the sewn object such as cloth and the movement amount of the sewn object, that is, the feed amount of the sewing machine, etc., is used as the bobbin thread. In the phase between the tightening phase and the top dead point phase of the balance, the bobbin thread is forcibly supplied in sequence, and the thickness of the sewn object such as cloth is detected, and the tightening amount (length) of the bobbin thread calculated from the thickness. A lockstitch sewing machine having a sewing thread control function, which is characterized by tightening the bobbin thread in the tightening phase.

The lockstitch sewing machine according to claim 1.

1 lockstitch sewing machine.

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