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

Abstract

This invention relates to a method for controlling low-speed thread rejection during sewing of fabric using a sewing machine. The sewing machine's needle and take-up lever are driven by the main shaft. The method includes the following steps: S1, determining the thread rejection safety aperture D1; determining the time t required from the moment the needle leaves the fabric upwards until the needle eye retracts to the thread rejection safety aperture D1. D S2, let A be the name of the S2. T / T=ω n Within one operating cycle, determine the angle A1 corresponding to the main shaft when the needle leaves the fabric upwards, and determine the angle A2 corresponding to the main shaft when the take-up lever ends the take-up action; S3, set the function ω=f(A) of the main shaft angular velocity with respect to the main shaft angle within one operating cycle, and satisfy the following condition: f(0)=f(A) T f(A) is continuously differentiable, and f′(0) = f′(A) T In the interval 0 to A1, ω increases to ω n And it continues to increase; at t1 = A1 / ω n The initial axis angle is A1; the time t2 for rotation to A2 satisfies t2-t1≤t D At time T, the principal axis angle is A. T S4. During one operating cycle, the spindle angle is acquired in real time, and the spindle rotation is controlled by the function relationship ω=f(A).

Description

Technical Field

[0001] This invention relates to the field of sewing technology, 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 stitching is a common manufacturing defect in high-density fabric, manifesting as loose stitches, especially noticeable at low sewing speeds. However, this loose stitching disappears when a certain angular velocity is exceeded. Specifically, during the sewing process, the needle leaves a needle-sized eye in the fabric as it penetrates and is withdrawn.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 variable angular velocity of the main shaft, the thread take-up action is completed before the needle eye 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 of 0 to Δ within one cycle of the needle's operation. T The start time of the operating cycle is denoted as 0 to T, and 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, let A be the name of the S2. T / T=ω n Within one operating cycle, based on the thickness of the fabric to be sewn, determine the angle A1 corresponding to the main shaft when the needle leaves the fabric upwards, and determine the angle A2 corresponding to the main shaft when the take-up lever ends the take-up action;

[0008] S3. Spindle angular velocity setting: Set the spindle angular velocity as a function of the spindle angle ω = f(A) over a running cycle, and satisfy the following condition: f(0) = f(A) T f(A) is continuously differentiable, and f′(0) = f′(A) T In the interval 0 to A1, ω increases to ω n And it continues to grow. t1=A1 / ω n ; t2-t1≤t D ;

[0009] S4. Sewing operation control: During one operation cycle, the spindle angle is acquired in real time, and the spindle rotation is controlled by the function relationship ω=f(A).

[0010] Furthermore, in step S1, the critical diameter D0 of the needle eye hole for sewing the fabric in the sewing machine is first determined, and the safe diameter D1 without sewing 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, in step S3, within the interval 0 to A1, the angular acceleration of the main shaft first increases and then decreases.

[0015] Furthermore, in step S3, within the interval A1 to A2, the angular velocity ω of the main shaft first increases and then decreases.

[0016] Furthermore, in step S3, the angular acceleration of the main shaft gradually decreases in the interval A1 to A2.

[0017] Furthermore, in step S3, in A2 to A T Within the interval, the angular velocity ω of the principal axis gradually decreases, and the angular acceleration first decreases and then increases.

[0018] Further, step S4 includes: obtaining the angle of the spindle, obtaining the theoretical angular velocity of the spindle according to the functional relationship ω=f(A), obtaining the actual angular velocity of the spindle by measurement, judging the error between the actual angular velocity and the theoretical angular velocity, if the error meets the requirements, the spindle continues to rotate, if the error does not meet the requirements, adjusting the drive source of the spindle to correct the actual angular velocity of the spindle so that the error meets the requirements to match the theoretical angular velocity.

[0019] As can be seen from the above, the control method of the present invention has the following beneficial effects:

[0020] 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; the angular velocity change of the spindle is more uniform, which is more conducive to electronic control debugging and reduces vibration and noise.

[0021] 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.

[0022] 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

[0023] Figure 1 This is a schematic diagram of the main shaft, thread take-up lever, and needle of the sewing machine in this invention.

[0024] Figure 2 This is a diagram showing the eye of a needle left after the needle leaves the fabric upwards in a sewing machine.

[0025] 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.

[0026] Figure 4 This is a schematic diagram illustrating the thread take-up lever in a sewing machine.

[0027] 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.

[0028] Figure 6 This is a schematic diagram of the relationship between the angular velocity and angle of the spindle in this invention.

[0029] Figure 7 This is a schematic diagram showing the change of the spindle's angular velocity over time in this invention.

[0030] Figure 8 This is a schematic diagram of the spindle angle within one operating cycle in this invention.

[0031] Figure 9 This is a schematic diagram of the spindle angular acceleration curve within one operating cycle in this invention.

[0032] Figure 10 This is a schematic diagram of the control logic for the spindle angular velocity in this invention.

[0033] Explanation of icon numbers

[0034] 1. Spindle

[0035] 2. Line-lifting lever

[0036] 3 needles

[0037] 4. Fabric

[0038] 5 pinholes

[0039] 6-sided lines

[0040] 7 bottom lines Detailed Implementation

[0041] 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.

[0042] 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.

[0043] See Figures 1 to 10 This invention provides a method for controlling low-speed thread slippage during sewing of fabric using a sewing machine. 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 of the needle 3 from its lowest point upwards and then downwards 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 TTypically, 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 can be recorded.

[0044] The control method of the present invention includes the following steps:

[0045] 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 the phenomenon of the top thread 6 being incorrectly pulled out during thread take-off. Determine the time t required from the moment the needle 3 leaves the fabric 4 upwards until the needle eye 5 retracts to the safe, thread-free aperture D1. D Time 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 .

[0046] In this embodiment, the safe diameter D1 without thread throwing is determined based on the critical diameter D0 of thread throwing, where D1 ≥ D0. The critical diameter D0 of 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 threads / 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 6 is pulled out incorrectly during thread lifting. The diameter of the smallest needle hole 5 that does not exhibit this phenomenon is taken as the critical diameter D0 of 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.

[0047] 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. DIn other embodiments, other suitable methods may be used to determine this, such as through simulation calculations.

[0048] S2, let A be the name of the S2. T / T=ω n The average angular velocity of the main shaft 1 is determined; within one operating cycle, based on the thickness of the fabric 4 to be sewn, the angle A1 corresponding to the main shaft 1 when the needle 3 leaves the fabric 4 upwards is determined, and the angle A2 corresponding to the main shaft 1 when the take-up lever 2 ends the take-up action is determined.

[0049] In existing conventional techniques, uniform rotation is generally used during sewing, and the average angular velocity of the spindle 1 during one operating cycle is denoted as ω. n The average angular velocity ω n This also refers to the operating speed set on the sewing machine panel on the control panel. During the sewing process, the electronic control system needs to control the average angular velocity of the spindle 1 to be ω within one operating cycle. n Average angular velocity ω n The settings are pre-defined in the control system based on the specific sewing machine's sewing operations. Angles A1 and A2, once determined, are also set via the control panel and input into the electrical control system.

[0050] S3, Spindle 1 angular velocity setting: See Figures 6 to 9 Set a function ω = f(A) for the angular velocity of spindle 1 with respect to the angle of spindle 1 during the running cycle, and satisfy the following conditions:

[0051] (a)f(0)=f(A T f(A) is continuously differentiable, and f′(0) = f′(A) T Since the sewing machine needle 3, thread take-up lever 2, and main spindle 1 all run continuously in sequence according to the operating cycle, the starting angular velocity and angular acceleration of the main spindle 1 in one operating cycle must be the same, and the angular velocity curve of the main spindle 1 is also smoothly changing, that is, continuously differentiable.

[0052] (b) In the interval 0 to A1, ω increases from ω0 to ω n And continue to increase to ω1, the corresponding time is denoted as 0~t1, see [reference]. Figure 7 , t1=A1 / ω n That is, the time corresponding to the angle A1 of principal axis 1 is t1 = A1 / ω. n The integral of the angular velocity with respect to time is the angle rotated by principal axis 1, and A(t) is the function of angle and time.

[0053] (c) t2-t1≤t DIn other words, when the spindle rotates to angle A1, this condition is used to ensure that no parabolic curve will occur. When spindle 1 rotates to angle A1, the corresponding time is t1, and the angular velocity is ω1, which is greater than ω. n The needle 3 leaves the fabric 4. In subsequent rotations, the main shaft 1 will operate faster than in the normal constant-speed mode, thus driving the take-up lever 2 to lift the thread upwards at a faster speed. The time to reach angle A2 is t2, which is longer than the time A2 / ω required in the constant-speed mode. n It needs to be done much earlier. At this point, the line-picking lever 2 has already finished picking up the line, and the time spent during this period is t2-t1≤t. D That is, before the diameter of the resulting pinhole 5 has shrunk to the safe aperture D1 without the need for line throwing, the line take-up rod 2 has already finished taking the line, ensuring that the surface line 6 will not be pulled out incorrectly during the line take-up process, thereby avoiding the formation of line throwing.

[0054] (d) That is, the main shaft 1 rotates to angle A. T The time taken is exactly T; this condition is used to meet the setting requirements for the normal operating cycle of the sewing machine.

[0055] See Figures 6 to 9 As a preferred design, in this embodiment, within the interval 0 to A1, as the angle A of principal axis 1 increases, the angular acceleration of principal axis 1 first increases and then decreases; correspondingly, the angular acceleration of principal axis 1 changes with time t, first increasing and then decreasing. Within the interval A1 to A2, as the angle A of principal axis 1 increases, the angular velocity ω of principal axis 1 first increases and then decreases; correspondingly, the angular acceleration of principal axis 1 changes with time t, first increasing and then decreasing, and the angular acceleration of principal axis 1 gradually decreases, changing from a positive number to a negative number. Within the interval A2 to A... T Within the interval, as the angle A of principal axis 1 increases, the angular velocity ω of principal axis 1 gradually decreases. Correspondingly, the angular acceleration of principal axis 1 also increases and then decreases with time t, and the angular acceleration first decreases and then increases, gradually becoming flat and then becoming 0.

[0056] As a preferred design, t D A T ω n Parameters such as A1 and A2 are input into the electronic control system, and the constraints of the function ω=f(A) mentioned above are set. The electronic control system then automatically generates a suitable specific function.

[0057] S4. Sewing operation control: In one operating cycle, the angle of spindle 1 is acquired in real time, and the rotation of spindle 1 is controlled by the function relationship ω=f(A).

[0058] See Figure 10In this embodiment, preferably, the angle of spindle 1 is obtained through an electronic control system. The theoretical angular velocity of spindle 1 is obtained according to the functional relationship ω = f(A), and the actual angular velocity of spindle 1 is measured using a protractor. The error between the actual and theoretical angular velocities is determined. If the error meets the requirements (e.g., actual angular velocity = theoretical angular velocity), spindle 1 continues to rotate. If the requirements are not met, the drive source (motor) of spindle 1 is adjusted. Specifically, the motor speed is adjusted by adjusting the current to correct the actual angular velocity of spindle 1, ensuring the error meets the requirements to match the theoretical angular velocity. The angle of spindle 1 can be determined by the electronic control system through cumulative calculation of the motor driving spindle 1, or it can be measured by an additional sensor.

[0059] After the main spindle 1 completes one operating cycle, it enters the next operating cycle. In each operating cycle, the main spindle 1 rotates in the same way, and the thread take-up lever 2 and the needle 3 move in the same way, continuously cycling according to the operating cycle.

[0060] 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.

[0061] As can be seen from the above, the control method of the present invention has the following beneficial effects:

[0062] 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, reducing the time to complete the take-up and avoiding the phenomenon of the top thread 6 being pulled out incorrectly during the take-up due to the shrinkage of the fabric 4, thereby avoiding the phenomenon of thread throwing; the angular velocity change of the spindle 1 is more uniform, which is more conducive to electronic control debugging and reduces vibration noise.

[0063] 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.

[0064] 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.

[0065] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0066] 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 of 0 to A within one cycle of the needle's operation. T The starting time of the operating cycle is denoted as 0 to T, and its characteristic is: 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, let A T / T=ω n Within one operating cycle, based on the thickness of the fabric to be sewn, determine the angle A1 corresponding to the main shaft when the needle leaves the fabric upwards, and determine the angle A2 corresponding to the main shaft when the take-up lever ends the take-up action; S3. Spindle angular velocity setting: Set the spindle angular velocity as a function of the spindle angle ω = f(A) over a running cycle, and satisfy the following condition: f(0) = f(A) T f(A) is continuously differentiable, and f′(0) = f′(A) T In the interval 0 to A1, ω increases to ω n And it continues to grow. t1=A1 / ω n ; t2-t1≤t D ; S4. Sewing operation control: During one operation cycle, the spindle angle is acquired in real time, and the spindle rotation is controlled by the function relationship ω=f(A).

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 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 slickering is determined, which is time t. D .

6. The control method according to claim 1, characterized in that: In step S3, within the interval 0 to A1, the angular acceleration of the main shaft first increases and then decreases.

7. The control method according to claim 1, characterized in that: In step S3, within the interval A1 to A2, the angular velocity ω of the main shaft first increases and then decreases.

8. The control method according to claim 7, characterized in that: In step S3, the angular acceleration of the main shaft gradually decreases in the interval A1 to A2.

9. The control method according to claim 1, characterized in that: In step S3, in A2 to A T Within the interval, the angular velocity ω of the principal axis gradually decreases, and the angular acceleration first decreases and then increases.

10. The control method according to claim 1, characterized in that: Step S4 includes: obtaining the angle of the spindle, obtaining the theoretical angular velocity of the spindle according to the functional relationship ω=f(A), obtaining the actual angular velocity of the spindle by measurement, judging the error between the actual angular velocity and the theoretical angular velocity, if the error meets the requirements, the spindle continues to rotate, if the error does not meet the requirements, adjusting the drive source of the spindle to correct the actual angular velocity of the spindle so that the error meets the requirements to match the theoretical angular velocity.

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