JP7266780B2 - Lockstitch sewing machine with sewing thread control function - Google Patents

Description

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

Problems to be solved by the present invention

For the seam quality of sewn products, a stable and moderate sewing force and stable repetition of the single stitch shape suitable for the sewn products are major evaluation requirements.

However, the current general 'mechanism and process of forming seams and generating sewing force' (hereafter referred to as 'conventional method') does not improve the sewing quality of the sewing product between sewing thread and cloth (material to be sewn), It is based on empirical rules that use the balance of the frictional force between the sewing thread and the sewing thread and the sewing machine parts so well that it is almost a "miracle".

At present, it is difficult to control the frictional force, and it is difficult to adjust the sewing machine to obtain a stable and appropriate sewing force and a stable repetition of the single stitch shape suitable for the sewn product.

In order to solve such current problems, stable quality is achieved by controlling the amount of thread consumed in one stitch without relying on the "miraculous balance based on empirical rules" that depends on the frictional force. Regarding the control of the bobbin thread, the inventors of the present invention have applied Japanese Patent Application No. 2020-66285 "Stitch Stabilizing Bobbin Thread Control Device" and Japanese Patent Application No. 2020-117384 "Stitch Stabilizing Bobbin Thread Control Device". Regarding this, Japanese Patent Application No. 2020-199883 "Lockstitch Sewing Machine Having Needle Thread Forced Supply Function" is presented.

However, in any case, the error between the calculated amount of thread and the amount of thread that should actually be used for stitching is compensated for by the frictional force of the lower thread in the case of a needle thread, or the upper thread in the case of a lower thread. ing.

Means to solve problems

According to the present invention, by using both the needle thread control and the bobbin thread control according to the above invention, the thickness of the material to be sewn such as cloth can be adjusted without completely relying on the "miracle balance based on empirical rules" that depends on the frictional force. The amount (length) of the needle thread used for the first stitch calculated from the thickness and the amount of movement of the material to be sewn, i.e., the feed amount of the sewing machine, etc., is controlled, and the amount of needle thread is forcibly fed out. Furthermore, by detecting the thickness of the material to be sewn 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, the amount of bobbin thread consumed in the first stitch. By directly or indirectly calculating the thread amount of the sewn thread to be sewn and controlling the amount, it is intended to control the stitching force and the stability of the stitch form.

Effect of the invention

By performing sewing using the lockstitch sewing machine having the sewing thread control function of the present invention, it is possible to realize a stable and moderate sewing force and a stable repetition of the single stitch shape suitable for the sewn product. good seam quality can be obtained.

Detailed description of the invention

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

The stitch forming process starts from the take-up top dead center phase (phase 1) and the feeding of the needle thread 13 inside the mechanism is started. After that, from the phase (phase 2) in which the thread hole of the needle passes through the throat plate (actually, the material to be sewn), the required amount of needle thread is generated, the needle thread loop capture phase (phase 4) at the blade point of the hook, and the needle thread After a phase (phase 8) in which the bobbin (bobbin thread storage section) passes through the loop, the needle thread 13 released in phase 8 is recovered by the take-up lever rising from the take-up thread take-up bottom dead center phase (phase 7). , through the feed start phase (phase 6 = the feed dog comes out to the upper surface of the throat plate), the needle thread 13 is tightened again at the take-up top dead center phase (phase 1'), and the bobbin thread tightening phase (phase 9). At , the final stitch (bobbin thread) is tightened to complete the formation of the first stitch.

In the motion diagram of FIG. 1, the feeding end phase (phase 10 = the feed dog sinks into the bottom surface of the throat plate) comes after the bobbin thread tightening phase (phase 9). This is to prevent the sewn cloth and sewing thread from being pulled back by the tightening of 13). It does not affect morphology.

Fig. 2 shows the state of the stitches (needle thread 13 and bobbin thread 14) near the stitches in the top dead center phases of the balance (phases 1 and 1') and the looper thread tightening phases (phases 9 and 9'). 3.

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

The behavior of the needle thread 13 associated with the stitch forming process begins in the sewing machine mechanism from the take-up top dead center (Phase 1) where the needle thread supply to the mechanism (the take-up needle thread supply curve) begins, and this phase is the stitch forming cycle. is the starting point of Then, from phase 2, the absorption of the upper thread requirement of the mechanism (hook upper thread requirement curve) begins. The difference between the thread take-up needle thread supply amount and the required hook thread amount in each phase is the "slack" of the needle thread 13. This "slack" is absorbed by the thread take-up spring 17.

When the phase advances past the bottom dead center of the needle bar (phase 3), as the needle rises, the required amount of upper thread on the hook continues to decrease, and the amount of upper thread on the thread take-up continues to increase. In the needle thread loop catching phase (phase 4) of the tip of the blade, the absorption capacity limit of the thread take-up spring 17 (absorption capacity limit of the stroke of the thread take-up spring) is exceeded, and "slack" actually occurs. The "slack" becomes a needle thread loop to be caught by the blade point of the hook.

After passing the needle thread loop capture phase (phase 4) of the blade point of the hook, the needle thread required amount starts to increase again, and the difference between the thread take-up needle thread supply amount and the hook needle thread required amount falls within the absorption capacity of the thread take-up spring 17. . The needle thread required amount continues to increase, and when the bobbin (bobbin thread storage portion) slips through the loop of the needle thread 13 (phase 8), the needle thread 13 is released from the blade point of the hook and suddenly decreases.

Further, the thread take-up thread supply amount also decreases at once when the thread take-up bottom dead center (phase 7) is passed. This decrease in the supply amount of the upper thread of the take-up lever serves to pull up the upper thread 13 released from the blade point of the hook to the upper surface of the cloth (material to be sewn).

Concurrently with this phenomenon, the feed dog appears on the upper surface of the throat plate (phase 6) and the horizontal feed functions, thereby feeding (moving) the material to be sewn and consuming the needle thread 13. .

FIG. 2 shows the stitch form and the state of the sewing thread (needle thread 13, bobbin thread 14) at the phase (phase 1') when the phase further advances and the balance top dead center is reached again.

During the period from phase 1 to phase 1′, the amount of needle thread (thread amount from 21 to 22) which is used for feeding and stitch formation is increased from the bottom dead point of the take-up (phase 7) to the top dead point of the take-up (phase 1 '), the upper thread is pulled out from the upper thread tension device (direction 18) against the upper thread tension pressure in the process of tightening (retrieving) the upper thread. At this time, a stable and appropriate sewing force is generated in the seam affected by the tension pressure of the upper thread.

In a further phase, in the bobbin thread tightening phase (phase 9), the needle thread 13 is pulled back into the fabric (workpiece) by the bobbin thread 14 to complete the stitch form as shown in FIG.

That is, the "conventional method" stitch forming cycle is approximately 400° starting from the top dead center of the thread take-up (phase 1) and ending at the final stitch (bobbin thread) tightening phase (phase 9).

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

Therefore, when the bobbin thread tightening phase (phase 9') passes and the normal thread path path is returned to, the bobbin thread amount corresponding to the bobbin thread tightening amount 12 becomes "slack in the bobbin thread 14".

This "slack in the bobbin thread 14" is consumed by "feeding the material to be sewn" or "entanglement with the needle thread 13". Until the phase (phase 5) where the cam surface 24 provided in the lower thread path comes to the lower thread path, "feeding of the material to be sewn" and "entanglement with the upper thread 13" do not occur, so the "lower thread 14 slacks" are never consumed. That is, there is no tightening and payout of the bobbin thread 14 at the second phase (phase 5) when the "cam surface provided on the shuttle" 24 comes to the bobbin thread path. In addition, in the bobbin thread feeding lever method, since the movement of the bobbin thread feeding lever is independent of the movement of the hook, it is possible to make sure that the "cam surface provided on the hook" comes to the bobbin thread path for the second time. no movement.
That is, in either method, the behavior of tightening and paying out the bobbin thread 14 at phase 5 on the motion diagram of FIG. 1 does not occur.

This "slack amount of the bobbin thread 14" is consumed sequentially from the feed start phase (phase 6) of the material to be sewn as the feed amount increases. It is raised to 13 and consumed. However, the amount of bobbin thread consumed by "feeding the material to be sewn" and "tightening the needle thread" is much larger than the "slack amount of the bobbin thread 14", and after the "slack amount" is consumed, As the (phase) advances, the bobbin thread 14 is pulled loosely from the bobbin (bobbin thread storage portion) against the bobbin thread tension spring.

As a result, the bobbin thread 14 in the take-up top dead center phase (phase 1') assumes the form shown in FIG. The helical stitch configuration (20 to 23) is completed.

FIG. 4 shows an example of the state of the bobbin thread 14 in the bobbin thread tightening phase (phase 9) using the cam surface 24 of the hook as the tightening mechanism. FIG. 5 shows an explanatory diagram of a change in the stitch form during transition from the take-up 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 in the area 25 indicated by the dashed line in the upper diagram of FIG. 5 is finally tightened and the stitch formation is completed. 5, the "final stitch (bobbin thread) tightening amount" is not theoretically quantified, and the sewing quality of the material to be sewn depends on the sewing thread and the cloth (the material to be sewn). It relies on the frictional force between the needle thread and the bobbin thread, the sewing thread and the peripheral member, and is secured by the "miraculous balance based on empirical rules" of the frictional force.

That is, since the "final stitch (bobbin thread) tightening amount" varies depending on the thickness of the material to be sewn, the bobbin thread tightening amount 12 in the bobbin thread tightening phases (phases 9 and 9') in 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) ) The "tightening bobbin thread amount" larger than the "tightening amount" is pulled out from the bobbin (bobbin thread storage portion) against the bobbin thread tension spring pressure.

From the above stitch forming process and the behavior of the needle thread 13 and the bobbin thread 14, a stable and moderate stitching force of the seam and a stable repetition of the single stitch shape suitable for the sewn product are obtained. It can be seen that it is based on empirical rules that skillfully use the balance of the frictional force between sewing thread and sewing thread, and sewing thread and sewing machine parts, so that it is almost a "miracle".

However, it is difficult to control the frictional force, and it is currently difficult to adjust the sewing machine to obtain a stable and moderate sewing force and to stably repeat the single stitch shape suitable for the sewn product. Detect the thickness of the material to be sewn, such as cloth, without relying entirely on the "miraculous balance based on empirical rules" that depend on the frictional force, and calculate from the thickness and the amount of movement of the material to be sewn, that is, the feed amount of the sewing machine. It controls the amount (length) of the upper thread used for the first stitch, forcibly feeds out the upper thread amount, and similarly detects the thickness of the material to be sewn, such as cloth, and calculates from the thickness. By controlling the bobbin thread tightening amount (length) of the first stitch and tightening the bobbin thread amount, that is, the amount of sewing thread (needle thread 13 and bobbin thread 14) consumed for the first stitch can be directly adjusted. Alternatively, it is intended to control the stability of the suturing force and stitch form by indirectly calculating and controlling the amount.

Based on the motion diagram modeled in FIG. 1, the stitch forming cycle and the stitch form cycle will be explained again.
The stitch forming cycle of the "conventional method" starts from the take-up top dead center phase (phase 1), and the needle thread 13 starts to be supplied inside the mechanism. ), the necessary amount of needle thread is generated from the phase (phase 2), the needle thread loop capture phase (phase 4) at the blade point of the hook, and the phase (phase 8) in which the bobbin (bobbin thread storage section) passes through the needle thread loop (phase 8). ), the thread take-up is lifted from the bottom dead center phase (phase 7), and the upper thread 13 released at phase 8 is recovered. ), the needle thread 13 is tightened again in the take-up top dead center phase (phase 1'), and the final stitch (bobbin thread) is tightened in the bobbin thread tightening phase (phase 9) to form the first stitch. is a cycle of approximately 400° ending with .

On the other hand, the stitch form cycle 26, as shown in FIG. 6, starts from the bobbin thread tightening phase (phase 9') in which the knot point of the bobbin thread is located in the thickness of the material to be sewn and the next same stitch is sewn. 360° cycle to bobbin thread tightening phase (phase 9) showing morphology.

In the present invention, the phases of each process are substantially the same as in the "conventional method" except that the starting point of the stitch forming cycle is the bobbin thread tightening phase (phase 9'). That is, the stitch formation cycle is completely the same in phase as the stitch formation cycle. A cycle of 360° up to the bobbin thread tightening phase (phase 9) showing the same stitch configuration.

As shown in FIG. 7, in the bobbin thread tightening phase (phase 9'), the stitches and the thread supply section (the thread feeder (18 direction) for the needle thread 13, and the bobbin thread storage section ( This is possible by tensioning the sewing thread (needle thread and bobbin thread) between the bobbin).

After passing the bobbin thread tightening phase (phase 9'), which is the end point of the previous stitch forming cycle, a new stitch forming cycle starts from the bobbin thread tightening phase (phase 9'), and the thickness of the material to be sewn such as cloth is started. is detected, and the amount (length) of the upper thread used for the first stitch calculated from the thickness and the amount of movement of the material to be sewn, that is, the feed amount of the sewing machine, etc. In the phase between , the needle thread feeder (direction 18) sequentially forcibly feeds the yarn. Ideally, between the bobbin thread tightening phase (phase 9') and the needle thread loop catching phase (phase 4) at the blade point of the hook, the needle thread loop to be caught by the blade point of the hook is of an appropriate and stable size. However, it is desirable that the remaining amount of yarn be supplied between the take-up bottom dead center phase (phase 7) and the take-up take-up top dead center phase (phase 1').

FIG. 8 shows the stitch pattern at the top dead center phase of the balance (phases 1 and 1') and the state of the stitch threads (needle thread 13 and bobbin thread 14) near the stitch. Fig. 8 shows the same form as Fig. 2, which is the stitch form at the take-up top dead center phase of the "conventional method" and the state of the sewing thread (needle thread 13 and bobbin thread 14) in the vicinity of the seam. It can be seen that the upper thread 13 is tightened in phases (phases 1' and 1).

The "amount (length) of needle thread consumed in one stitch" forcibly supplied varies from 20 to Consumed by 23 top thread lengths.

The stitch form and the state of the sewing thread at the take-up top dead center phases (phases 1' and 1) in the middle of the stitch forming cycle are shown in FIG. (Fig. 8) The length of the needle thread "15 to the length of the thread take-up thread holes 16 to 18" differs greatly, and due to this difference, the tightening tension of the needle thread is generated and transmitted to the needle threads of 20 to 15. . The relationship between the end point (start point) phase (Fig. 7) and the thread take-up top dead center phase (Fig. 8) in the middle of the stitch forming cycle is basically (20 to 23 to 15 to 19 in Fig. 7). The length of the thread take-up thread holes 16 to 18 at the position of )=(the length of the thread take-up 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 material to be sewn such as cloth is detected, and the thickness and the amount of movement of the material to be sewn, that is, the sewing machine

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

In addition, since the needle thread length from 20 to 15 differs depending on the thickness of the material to be sewn and the feed amount generated from the thread take-up top dead center phase (phase 1') to the bobbin thread tightening phase (phase 9), the end point ( The starting point phase (Fig. 7) and the end point phase (bobbin thread tightening phase (phase 9 and 9')) The upper thread path length between 15-18 in FIG. 7 must be changed.

This can be dealt with by changing the position 19 of the thread take-up thread hole 16 . That is, by changing the phase of the end point phase (bobbin thread tightening phase (phases 9 and 9')) in accordance with the detected thickness of the sewing material, the countermeasure can be taken.

On the other hand, the behavior of the bobbin thread 14 also starts from the bobbin thread tightening phase (phase 9') of the previous stitch. Explain using an explanatory diagram.

In the bobbin thread tightening phase (phase 9'), which is the starting point of the stitch forming cycle, the bobbin thread guide member 27 is operated, and the bobbin thread path is adjusted to the bobbin thread tightening amount of the previous stitch. The bobbin thread amount (b+ca) is longer than the normal bobbin thread path.

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

This "slack amount of the bobbin thread 14" is consumed sequentially from the feed start phase (phase 6) of the material to be sewn as the feed amount increases. It is raised to 13 and consumed. However, the amount of bobbin thread consumed by "feeding the material to be sewn" and "tightening the upper thread" is much larger than the "amount of slack in the bobbin thread 14". As the consumption (phase) progresses, the bobbin thread 14 is pulled loosely from the bobbin (bobbin thread storage portion) against the bobbin thread tension spring.

As a result, the bobbin thread 14 in the take-up top dead center phase (phase 1') assumes the form shown in FIG. The helical stitch configuration (20 to 23) is completed.

In the "conventional method", the "final stitch (bobbin thread) tightening amount" is not theoretically quantified. It relies on the frictional force of the members, and is ensured by the "miracle balance based on empirical rules" of the frictional force.

The present invention quantifies the "final stitch (bobbin thread) tightening amount" and controls the amount to stably improve the sewing quality. do.

FIG. 5 is also an explanatory diagram showing changes in the state of the sewing thread (needle thread 13 and bobbin thread 14) from the take-up top dead center phase (FIG. 8) to the bobbin thread tightening phase (stitch formation cycle end point phase (FIG. 7)). . In the bobbin thread tightening phase, the bobbin thread 14 is tightened in the area 25 indicated by the dashed line in the upper diagram of FIG. A height 28 of the presser foot 29 from the upper surface 30 of the throat plate can be detected using a differential transformer or the like. The bobbin thread tightening amount thus detected and calculated is tightened by the method shown in FIG.

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

This amount of change b+c−a corresponds to the bobbin thread amount spent in the range 25 indicated by the broken line in the upper diagram of FIG. Therefore, if the bobbin thread 14 is supplied from the thread supply side to the amount of change in the amount of thread b+c−a between the thread guide members 31 and 32, then "(the amount of change in the amount of thread between the thread guide members 31 and 32 b+c−a) = (amount of bobbin thread used in range 25 indicated by the dashed line in the upper diagram of FIG. 5)” does not hold true. In the tightening phase, the thread holding/operating member 33 operates to fix the bobbin thread 14 and cut 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 thickness of the cloth (material to be sewn) is detected and the calculated lower

It is absorbed by the deformation of the cloth (material to be sewn) caused by the tension 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

can be controlled. In other words, let L be the total amount of sewing thread consumed in the thickness direction of the cloth.

The "stitch crossing ratio" is a numerical value that indicates what percentage of the thickness of the material to be sewn, when viewed from the upper thread side of the material, where the knot point of the needle thread and the bobbin thread is located. However, it is generally said that a "seam crossing ratio of 60%" is good for the "beauty" of the seams of the material to be sewn when viewed from the upper thread side, and does not affect the sewing force. It is

FIG. 1 is a motion diagram that models the movement of a general sewing machine mechanism and the behavior of sewing threads (needle thread 13 and bobbin thread 14). FIG. 2 is a diagram showing the stitch pattern of the "conventional method" at the top dead center phases of the balance (phases 1 and 1') and the state of the sewing thread (needle thread 13 and bobbin thread 14) in the vicinity of the seam. FIG. 3 is a diagram showing the stitch form of the bobbin thread tightening phase (phases 9 and 9') of the "conventional method" and the state of the sewing thread (needle thread 13 and bobbin thread 14) near the seam. FIG. 4 is an explanatory view showing the state of the bobbin thread 14 in the bobbin thread tightening phase (phase 9) by using the cam surface of the hook as the tightening mechanism. FIG. 5 is an explanatory diagram of a change in the stitch pattern during the transition from the top dead center phase of the thread take-up (phase 1') to the bobbin thread tightening phase (phase 9). FIG. 6 is an explanatory diagram of the stitch form cycle. FIG. 7 is a diagram showing the stitch configuration of the looper thread tightening phases (phases 9 and 9') of the present invention and the state of the sewing thread (needle thread 13 and looper thread 14) in the vicinity of the seam. FIG. 8 is a diagram showing the stitch pattern of the top dead center phases of the balance (phases 1 and 1') and the state of the stitch threads (needle thread 13 and bobbin thread 14) in the vicinity of the stitches of the present invention. FIG. 9 is an explanatory diagram of the basic form of the bobbin thread tightening function.

1 and 1': top dead center phase of the balance, 2: phase in which the thread hole of the needle passes through the throat plate (actually, the material to be sewn), 3: bottom dead center phase of the needle bar, 4. . . . Needle thread loop capture phase of hook blade point, 5 . 7: thread take-up bottom dead center phase; 8: phase in which the bobbin (bobbin thread storage section) passes through the needle thread loop; 9 and 9': bobbin thread tightening phase , 10 . Lower thread 15 Contact point between upper thread and presser 16 Thread take-up hole 17 Thread take-up spring 18 Direction to upper thread tension device (thread supplier) 19. ..Take-up thread hole position in bobbin thread tightening phase (phases 9 and 9)', 20 . Needle thread reference position at dead point phase 23 New stitch position 24 Cam surface provided on hook 25 Range of bobbin thread 14 to be tightened at bobbin thread tightening phase 26 1 stitch form cycle (1 stitch length), 27 . 29: Presser, 30: Upper surface of the throat plate, 31: Thread path member on the bobbin thread supply side, 32: Thread path member on the side of the material to be sewn, 33: Thread holding operation member

Claims (3)

The thickness of the material to be sewn, such as a cloth, is detected, and the amount (length) of the upper thread used for the first stitch calculated from the thickness and the amount of movement of the material to be sewn, that is, the feed amount of the sewing machine, etc. In the phases between the tightening phase and the take-up top dead center phase, the bobbin thread is forcibly fed in sequence, the thickness of the material to be sewn such as cloth is detected, and the tightening amount (length) of the bobbin thread is calculated from the thickness. is tightened in a bobbin thread tightening phase.

2. The lockstitch sewing machine according to claim 1.

1 lockstitch sewing machine.

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