A control method for low-speed non-thread throwing of a sewing machine when sewing fabric

Abstract

The present application relates to a kind of sewing machine sewing cloth low-speed non-throwing thread control method, the needle and thread tension lever of the sewing machine are driven by main shaft, comprising the following steps: S1, determine no-throwing thread safety aperture D1;Determine the time t required from the needle upwardly away from fabric to needle eye hole shrink to no-throwing thread safety aperture D1 D ;S2, parameter setting: set △A1 and △A2;Set △t1 and △t2, or set a1 and a2;In a running cycle, determine the corresponding phase angle A0 of main shaft when needle upwardly away from fabric, the phase angle A1 of main shaft when thread tension action ends;Set average speed ω0;Speed ω1 is set, ω1≥(A1-A0) / t D ;S3, calculate ω2;S4, when main shaft angle≤A0-A1, main shaft speed ω2;When A0-A1<main shaft angle≤A0, main shaft accelerates to ω1;When A0<main shaft angle≤A1, main shaft speed ω1;When A1<main shaft angle≤A1+△A1, main shaft decelerates to ω2;When main shaft angle>A1+△A1 degree, main shaft speed ω2.

Description

Technical Field

[0001] This invention relates to the field of sewing technology, and specifically to a method for controlling low-speed sewing without thread slippage when a sewing machine is sewing fabric. Background Technology

[0002] High-density fabric typically refers to a tightly woven fabric with a total warp and weft yarn density exceeding 800 threads / 10cm, characterized by fine yarns and small fiber gaps. Loose stitches are a common manufacturing defect in high-density fabric, manifesting as loose threads, especially noticeable at low sewing speeds. However, this loose stitching disappears at higher speeds. Specifically, during sewing, the needle leaves a small needle-like hole in the fabric as it penetrates and is withdrawn. (See Appendix) Figure 2 As shown, the size of needle holes in ordinary fabrics produced by machine needle punching remains largely unchanged (or shrinks very slightly) over time. However, due to its inherent characteristics—high warp and weft yarn density and tight weave—the needle holes in high-density fabrics gradually shrink over time; the higher the density, the faster the needle holes shrink. In the subsequent lockstitch formation process, the bobbin thread and top thread are successfully hooked together under the fabric using a rotary hook structure, completing the thread knot. The take-up lever then begins to take the thread up. (See Appendix) Figure 3 As shown, when the take-up lever is raised to retrieve the right-hand thread, the thread knot moves to the center of the fabric (i.e., into the needle eye). See attached diagram. Figure 4 As shown, the take-up is complete. When the take-up lever is taking up the right side of the top thread, if the eyelet is large, the right side of the top thread will not pull the left side of the top thread upwards. However, if the eyelet is too small, it will squeeze the top threads on both sides, causing them to come together under pressure. The right side of the top thread will then pull the left side of the top thread upwards, bringing it out as well. For ease of explanation, in this application, this phenomenon is referred to as the incorrect pulling out of the top thread during take-up. Because the take-up lever also feeds the fabric upwards, the fabric moves to the left. The top thread that has been pulled out on the left side may be held down by the presser foot. The low thread tension cannot pull out the top thread held down by the presser foot. Therefore, after feeding, there will be excess top thread (i.e., the portion held down by the presser foot). See Appendix. Figure 5 As shown, this results in thread sagging. For ease of explanation, in this application, the maximum diameter of the needle eye when the right-side thread moves upward, causing the left-side thread to move, is denoted as the critical diameter D0 for thread sagging. This critical diameter D0 is determined by the characteristics of the sewing machine, with key factors including thread take-up tension and thread thickness. Therefore, if the needle eye diameter is less than or equal to D0 after the needle leaves the fabric upward and the take-up lever begins to take in the thread, the aforementioned thread sagging problem will occur.

[0003] For high-density fabrics, the needle eye gradually shrinks after the needle leaves the needle plate. During low-speed sewing, if the needle eye shrinks too quickly, it may have already shrunk to less than or equal to the critical diameter D0 for thread slippage by the time the take-up lever begins to pull the thread up. This can lead to the take-up lever pulling up the right-side thread along with the left-side thread. During sewing, it's unavoidable to slow down at certain critical points. Slowing down in high-density fabrics can easily cause thread slippage, affecting garment quality. Currently, when encountering high-density fabrics, increasing thread tension is often used to mitigate thread slippage. However, increasing thread tension increases the probability of thread breakage, affecting the sewing effect and garment quality. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the technical problem to be solved by the present invention is to provide a control method for preventing thread slippage when sewing fabric at low speed. By controlling the spindle to move at a variable speed, the thread take-up action is completed before the needle eye hole shrinks to a certain extent, thus avoiding thread slippage.

[0005] To achieve the above objectives, the present invention provides a control method for preventing thread slippage at low speeds when sewing fabric with a sewing machine. The sewing machine's needle and take-up lever are driven by a main shaft, and the main shaft rotates at an angle A corresponding to one needle cycle. T The control method includes the following steps:

[0006] S1. Determine the safe, thread-free eye diameter D1 of the needle eye when sewing fabric in a sewing machine. Under this safe, thread-free eye diameter D1, the needle eye will not experience incorrect thread pull-out during thread take-up. Determine the time t required from the moment the needle leaves the fabric upwards until the needle eye shrinks to the safe, thread-free eye diameter D1. D ;

[0007] S2. Parameter Settings: Set the spindle's acceleration phase angle △A1 and deceleration phase angle △A2; set the acceleration time △t1 and deceleration time △t2, or set the acceleration a1 and deceleration a2; within one operating cycle, determine the phase angle A0 of the spindle when the needle leaves the fabric upwards, based on the thickness of the fabric to be sewn, and determine the phase angle A1 of the spindle at the end of the take-up action; set the average spindle speed ω0 within the operating cycle; set the speed ω1, where ω1 is the average speed of the spindle rotating from phase angle A0 to phase angle A1, and satisfies ω1≥(A1-A0) / t D ;

[0008] S3, according to A T / ω0=(A1-A0) / ω1+(A0+A T ω2 can be calculated by (-A1-△A0-△A1) / ω2+△t1+△t2; or by using A T / ω0=(A1-A0) / ω1+(A0+AT ω2 is obtained by calculating (-A1-△A0-△A1) / ω2+(ω1-ω2) / a1+(ω1-ω2) / a2;

[0009] S4. Sewing Operation Control: The spindle angle is acquired in real time. In one operating cycle, when the spindle angle is ≤ A0-A1, the spindle runs at a speed of ω2; when A0-A1 < spindle angle ≤ A0, the spindle speed is increased until ω1; when A0 < spindle angle ≤ A1, the spindle runs at a speed of ω1; when A1 < spindle angle ≤ A1+△A1, the spindle speed is decreased until ω2; when the spindle angle is > A1+△A1 degrees, the spindle runs at a speed of ω2 until the end of the operating cycle.

[0010] Furthermore, in step S1, the critical diameter D0 of the needle eye hole when the fabric is sewn in the sewing machine is first determined, and the safe diameter D1 without sizing is determined based on the critical diameter D0, where D1 ≥ D0.

[0011] Furthermore, in step S1, the critical diameter D0 of the parabolic trajectory and the time t D This was obtained through multiple simulation experiments.

[0012] Further, in step S1, the method for determining the critical diameter D0 for thread throwing is as follows: In the sewing machine, multiple needle holes of different diameters are drilled on the fabric according to a certain diameter gradient. In each needle hole of different diameters, the action of the needle moving upward and the take-up lever lifting the top thread is simulated when the needle leaves upward during normal sewing. The phenomenon of the top thread being pulled out incorrectly during take-up is observed. The diameter of the smallest needle hole that does not exhibit this phenomenon is taken as the critical diameter D0 for thread throwing.

[0013] Furthermore, in step S1, time t D The method for determining the needle eye size is as follows: In the sewing machine, for the fabric to be sewn, the needle is inserted into the fabric, and then the needle is moved upwards while recording the changes in the needle eye. The time elapsed from when the needle leaves the fabric until the needle eye shrinks to the safe diameter D1 without slickering is determined, which is time t. D .

[0014] Furthermore, the spindle is controlled by an electronic control system, and in step S1, time t D The values ​​are input to the electronic control system; in step S2, △A1, △A2, △t1, △t2, a1, a2, ω1, A0, and A1 are all input to the electronic control system; in step S3, the electronic control system automatically calculates ω2; in step S4, the electronic control system acquires and determines the spindle angle and controls the spindle movement.

[0015] Furthermore, the electronic control system includes a control panel, through which various parameters are set and input into the electronic control system.

[0016] Furthermore, in step S2, after ω1, A0, and A1 are input, the electronic control system automatically verifies whether ω1≥(A1-A0) / t is satisfied. D .

[0017] Furthermore, the fabric is a high-density fabric.

[0018] As described above, the control method of the present invention has the following beneficial effects:

[0019] 1. By changing the spindle speed within the cycle, the spindle speed within the angle range from the needle exiting the fabric to the end of the take-up is increased, reducing the time to complete the take-up and avoiding the phenomenon of incorrect thread pulling out during take-up caused by fabric shrinkage, thereby avoiding thread throwing.

[0020] 2. It can be well used for sewing high-density fabrics, overcoming the problem of easy thread breakage in high-density fabrics, and can broaden the adaptability to fabrics of different thicknesses and densities.

[0021] 3. No structural adjustments to the sewing machine are required; it can be adapted to different types of fabric simply by changing the control method, resulting in low improvement costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the main shaft, thread take-up lever, and needle of the sewing machine in this invention.

[0023] Figure 2 This is a diagram showing the eye of a needle left after the needle leaves the fabric upwards in a sewing machine.

[0024] Figure 3 This is a schematic diagram illustrating the operation of the thread take-up lever in a sewing machine as it begins to lift the thread upwards.

[0025] Figure 4 This is a schematic diagram illustrating the thread take-up lever in a sewing machine.

[0026] Figure 5 A schematic diagram illustrating the process of the presser foot in a sewing machine pressing down on the top thread to create a raised thread.

[0027] Figure 6 This is a schematic diagram of the relationship curve between spindle speed and spindle angle in this invention.

[0028] Figure 7 This is a schematic diagram of the relationship between the spindle speed and the spindle angle of the present invention.

[0029] Explanation of icon numbers

[0030] 1. Spindle

[0031] 2. Line-lifting lever

[0032] 3 needles

[0033] 4. Fabric

[0034] 5 pinholes

[0035] 6-sided line

[0036] 7 bottom lines Detailed Implementation

[0037] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0038] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0039] See Figures 1 to 7 This invention provides a method for controlling low-speed thread slippage when a sewing machine is sewing fabric 4. The sewing machine needle 3 and thread take-up lever 2 are driven by the main shaft 1. During normal sewing, the main shaft 1 rotates, causing the needle 3 and thread take-up lever 2 to move cyclically along a certain motion trajectory. In this invention, the movement process of the needle 3 moving upward from its lowest point and then downward back to its lowest point can be recorded as one operating cycle. The angle of rotation of the main shaft 1 within one operating cycle of the needle 3 is A. T A T Typically, it is 360°. Preferably, the movement of the main shaft 1 is controlled by the electronic control system of the sewing machine. The main shaft 1 is controlled by a motor, and the electronic control system is connected to the motor control system. By controlling the rotation speed of the motor, the rotation speed of the main shaft 1 is controlled, and the rotation angle of the main shaft 1 is recorded.

[0040] The control method of the present invention includes the following steps:

[0041] S1. Determine the safe, thread-free aperture D1 of the needle eye 5 when sewing fabric 4 in the sewing machine. Under the safe, thread-free aperture D1, the needle eye 5 will not experience incorrect thread pull-out during thread take-up. Determine the time t required from the moment the needle 3 leaves the fabric 4 until the needle eye 5 retracts to the safe, thread-free aperture D1. DTime t D The input is fed into the electrical control system. Preferably, the electrical control system includes a control panel, through which the time t is set. D The time t is then input into the electronic control system. When sewing different fabrics 4, the corresponding time t is modified and input through the control panel. D .

[0042] In this embodiment, the safe diameter D1 without thread throwing is determined based on the critical diameter D0 for thread throwing, where D1 ≥ D0. The critical diameter D0 for thread throwing can be determined through multiple simulation tests on fabric 4 in a sewing machine. Specifically, a low-density fabric 4 (e.g., fabric with a total warp and weft yarn density of less than 500 yarns / 10cm) can be used in the sewing machine. It is required that the needle holes 5 drilled on the fabric 4 will not shrink, or the shrinkage is less than the required value and can be ignored. Multiple needle holes 5 of different diameters are drilled in the low-density fabric 4, with the needle holes 5 set according to a certain diameter gradient from small to large, for example, the diameter gradient can be 0.1mm. The action of the needle 3 lifting the thread 6 upward after leaving the needle hole 5 during normal sewing is simulated in each needle hole 5 of different diameters, and it is observed whether the thread is incorrectly pulled out during thread lifting. The diameter of the smallest needle hole 5 that does not exhibit this phenomenon is taken as the critical diameter D0 for thread throwing. To allow for a safety margin, the safety aperture D1 without parabolic curves can also be chosen to be an appropriate value larger than the critical diameter D0 of the parabolic curve. In other embodiments, it can also be determined in other suitable ways, such as through simulation calculations.

[0043] In this embodiment, time t D The determination of the needle eye 5 can be achieved through multiple simulation experiments on fabric 4 in a sewing machine. Specifically, for the fabric 4 to be sewn, the needle 3 is inserted into the fabric 4 and then moved upwards. At the same time, the changes in the needle eye 5 can be recorded using methods such as high-frequency photography. Based on the captured images and time, the time elapsed from when the needle 3 leaves the fabric 4 until the needle eye 5 shrinks to the safe diameter D1 without thread spread is determined, which is time t. D In other embodiments, other suitable methods may be used to determine this, such as through simulation calculations.

[0044] S2. Parameter Settings: Set the acceleration phase rotation angle △A1 and deceleration phase rotation angle △A2 of spindle 1; set the acceleration time △t1 and deceleration time △t2, or set the acceleration a1 and deceleration a2; within one operating cycle, based on the thickness of the fabric 4 to be sewn, determine the phase angle A0 corresponding to spindle 1 when needle 3 leaves fabric 4 upwards, and determine the phase angle A1 corresponding to spindle 1 when take-up lever 2 ends the take-up action; set the average rotational speed ω0 of spindle 1 within the operating cycle; set the rotational speed ω1, ω1 as the average rotational speed of spindle 1 from phase angle A0 to phase angle A1, and satisfy ω1≥(A1-A0) / tD Starting from phase angle A1, the principal axis 1 is A0+A T The velocity within the angular range (i.e., within the range of A0 in the next running cycle) is denoted as ω2.

[0045] In existing conventional technology, sewing generally employs uniform motion. The average rotational speed of the spindle 1 within one operating cycle is denoted as ω0. This average rotational speed ω0 is also the design rotational speed set on the sewing machine's control panel. During the sewing process, the electronic control system needs to control the average rotational speed of the spindle 1 within one operating cycle to ω0. The average rotational speed ω0 is preset in the control system based on the specific sewing operation of the sewing machine.

[0046] join Figure 6 and Figure 7 In this invention, within one operating cycle, the main shaft 1 is switched to variable speed motion. After determining A0 and A1, a suitable rotational speed ω1 is determined as the average rotational speed of the main shaft 1 from phase angle A0 to phase angle A1, and ω1 ≥ (A1 - A0) / t is satisfied. D That is, t D ≥(A1-A0) / ω1, so when the main shaft 1 moves at a speed of ω1, after the needle 3 leaves the fabric 4, before the diameter of the resulting needle eye 5 shrinks to the safe diameter D1 without thread loss, the take-up lever 2 has already finished taking up the thread. Therefore, during the A0 to A1 stage, when running at a speed of ω1, there will be no phenomenon of incorrect thread being pulled out during take-up. The speed ω1 is set through the control panel and input to the electrical control system. After input, the electrical control system uses the formula ω1≥(A1-A0) / t to determine the speed. D Perform a second verification to avoid inputting incorrect data.

[0047] Within the remaining angular range of the operating cycle, spindle 1 primarily moves at a speed of ω2. Speed ​​ω1 is higher than the average speed ω0, while speed ω2 is lower than the average speed ω0. Therefore, spindle 1 experiences an acceleration phase near angle A0, increasing from speed ω2 to speed ω1. The angle traversed by spindle 1 during this acceleration phase is denoted as △A1. Correspondingly, to control the speed of acceleration, the corresponding acceleration time △t1 or acceleration a1 can be set. Similarly, spindle 1 experiences a deceleration phase near angle A1, decreasing from speed ω1 to speed ω2. The angle traversed by spindle 1 during this acceleration phase is denoted as △A2. Correspondingly, to control the speed of acceleration, the corresponding acceleration time △t2 or acceleration a2 can be set. △A1, △A2, △t1, △t2, a1, and a2 can be specifically set according to the characteristics of the motor driving spindle 1 to make the speed change process as smooth as possible. These parameters are set through the control panel and input into the electronic control system, which then automatically retrieves, calculates, and performs logical judgments.

[0048] S3, according to A T / ω0=(A1-A0) / ω1+(A0+A T ω2 can be calculated by (-A1-△A0-△A1) / ω2+△t0+△t1; or by using A T / ω0=(A1-A0) / ω1+(A0+A T ω2 is calculated by adding (ω1-ω2) / a1+(ω1-ω2) / a2. This method ensures that spindle 1 maintains an average rotation of ω0 within one operating cycle, meeting the operational requirements.

[0049] S4. Sewing operation control: See Figure 6 and Figure 7 The spindle 1 angle is acquired in real time. Within one operating cycle, the following judgments are made: When the spindle 1 angle ≤ A0-A1, spindle 1 operates at speed ω2; when A0-A1 < spindle 1 angle ≤ A0, the spindle 1 speed is increased until ω1; when A0 < spindle 1 angle ≤ A1, spindle 1 operates at speed ω2 to ensure that the top line is not incorrectly pulled out during line picking; when A1 < spindle 1 angle ≤ A1+△A1, the spindle 1 speed is decreased until ω2; when the spindle 1 angle > A1+△A1 degrees, spindle 1 operates at speed ω2 until the end of the operating cycle, then enters the next operating cycle, repeating the above process, i.e., the spindle 1 angle ranges from A1+△A1 to A0+A1 degrees. T Within the specified range, the spindle 1 rotates at a speed of ω2. In each operating cycle, the spindle 1, take-up lever 2, and needle 3 move in the same manner, continuously cycling according to the operating cycle.

[0050] The control method of the present invention can be used for sewing high-density fabric 4, and based on its principle, it can also be used for sewing low-density fabric 4.

[0051] As can be seen from the above, the control method of the present invention has the following beneficial effects:

[0052] 1. By changing the spindle speed within the cycle, the spindle speed of the spindle 1 is increased within the angle range from when the needle 3 exits the fabric 4 to when the thread take-up ends. This reduces the time required to complete the take-up and avoids the phenomenon of incorrect thread pulling out during take-up caused by the shrinkage of the fabric 4, thereby preventing thread slippage.

[0053] 2. It can be well used for sewing high-density fabric 4, overcoming the problem of easy thread breakage in high-density fabric 4, and expanding its adaptability to fabrics 4 of different thicknesses and densities.

[0054] 3. No structural adjustments to the sewing machine are required; it can adapt to different types of fabric simply by changing the control method. 4. The improvement cost is low.

[0055] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0056] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for controlling low-speed thread slippage during sewing of fabric in a sewing machine, wherein the sewing machine's needle and take-up lever are driven by a main shaft, and the main shaft rotates at an angle A corresponding to one operating cycle of the needle. T Its features are: The control method includes the following steps: S1. Determine the safe, thread-free eye diameter D1 of the needle eye when sewing fabric in a sewing machine. Under this safe, thread-free eye diameter D1, the needle eye will not experience incorrect thread pull-out during thread take-up. Determine the time t required from the moment the needle leaves the fabric upwards until the needle eye shrinks to the safe, thread-free eye diameter D1. D ; S2. Parameter Settings: Set the spindle's acceleration phase angle △A1 and deceleration phase angle △A2; set the acceleration time △t1 and deceleration time △t2, or set the acceleration a1 and deceleration a2; within one operating cycle, determine the phase angle A0 of the spindle when the needle leaves the fabric upwards, based on the thickness of the fabric to be sewn, and determine the phase angle A1 of the spindle at the end of the take-up action; set the average spindle speed ω0 within the operating cycle; set the speed ω1, where ω1 is the average spindle speed from phase angle A0 to phase angle A1, and satisfies ω1≥(A1-A0) / t D ; S3, according to A T / ω0=(A1-A0) / ω1+(A0+A T ω2 can be calculated by (-A1-△A0-△A1) / ω2+△t1+△t2; or by using A T / ω0=(A1-A0) / ω1+(A0+A T ω2 is calculated by (A1-△A0-△A1) / ω2+(ω1-ω2) / a1+(ω1-ω2) / a2; where ω2 is the principal axis starting from the phase angle A1, and A0+A T Speed ​​within the angular range; S4. Sewing Operation Control: The spindle angle is acquired in real time. In one operating cycle, when the spindle angle is ≤ A0-A1, the spindle runs at a speed of ω2; when A0-A1 < spindle angle ≤ A0, the spindle speed is increased until ω1; when A0 < spindle angle ≤ A1, the spindle runs at a speed of ω1; when A1 < spindle angle ≤ A1+△A1, the spindle speed is decreased until ω2; when the spindle angle > A1+△A1, the spindle runs at a speed of ω2 until the end of the operating cycle.

2. The control method according to claim 1, characterized in that: In step S1, the critical diameter D0 of the needle eye hole when the fabric is sewn in the sewing machine is first determined, and the safe diameter D1 without styling is determined based on the critical diameter D0, where D1 ≥ D0.

3. The control method according to claim 2, characterized in that: In step S1, the critical diameter D0 of the parabola and the time t are... D This was obtained through multiple simulation experiments.

4. The control method according to claim 3, characterized in that: In step S1, the method for determining the critical diameter D0 for thread throwing is as follows: In the sewing machine, multiple needle holes of different diameters are drilled on the fabric according to a certain diameter gradient. The action of the needle moving upward and the take-up lever lifting the top thread when the needle leaves upward during normal sewing is simulated in each needle hole of different diameters. The phenomenon of the top thread being pulled out incorrectly during take-up is observed. The diameter of the smallest needle hole that does not exhibit this phenomenon is taken as the critical diameter D0 for thread throwing.

5. The control method according to claim 3, characterized in that: In step S1, time t D The method for determining the needle eye size is as follows: In the sewing machine, for the fabric to be sewn, the needle is inserted into the fabric, and then the needle is moved upwards while recording the changes in the needle eye. The time elapsed from when the needle leaves the fabric until the needle eye shrinks to the safe diameter D1 without any slickness is determined, which is time t. D .

6. The control method according to claim 1, characterized in that: The spindle is controlled by an electronic control system. In step S1, time t D The values ​​are input to the electronic control system; in step S2, △A1, △A2, △t1, △t2, a1, a2, ω1, A0, and A1 are all input to the electronic control system; in step S3, the electronic control system automatically calculates ω2; in step S4, the electronic control system acquires and determines the spindle angle and controls the spindle movement.

7. The control method according to claim 6, characterized in that: The electrical control system includes a control panel, through which various parameters are set and input into the electrical control system.

8. The control method according to claim 6, characterized in that: In step S2, after ω1, A0, and A1 are input, the electronic control system automatically verifies whether ω1≥(A1 - A0) / t is satisfied. D .

9. The control method according to claim 1, characterized in that: The fabric is a high-density fabric.

Images