Yarn feeding method of flat knitting machine

Abstract

The invention discloses a yarn feeding method of a flat knitting machine. The yarn feeding method comprises the following steps in sequence: a traction step: pulling yarns through a traction mechanism; primary buffering is conducted on the yarn through a main buffering piece close to the downstream position of the traction mechanism, and the main buffering piece always exerts lifting first tensioning force on the yarn guided by the main buffering piece through a yarn guiding part of the main buffering piece; secondary buffering is conducted on the yarn through a secondary buffering piece close to the upstream position of the yarn nozzle, and the secondary buffering piece always exerts lifting second tensioning force on the yarn guided by the secondary buffering piece through a yarn guiding part of the secondary buffering piece; a yarn supply step: guiding the buffered yarn to supply the yarn to a yarn bed through a yarn nozzle; and a knitting step: knitting the yarns provided by the yarn nozzle through a yarn bed. The yarn tension control device has the beneficial effect that the yarn tension stability is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a yarn feeding method, in particular a yarn feeding method for a flat knitting machine. BACKGROUND

[0002] In the yarn feeding process of a flat knitting machine, the process flow commonly adopted by the prior art is: the yarn is pulled out by a traction mechanism, then a single buffer link (such as a buffer rod driven by a torque motor) applies tension to the entire section of yarn, and finally the yarn is delivered to the yarn bed through the yarn nozzle for knitting. However, with the development of high-speed and fine knitting processes (such as sesame point jacquard processes that require high-frequency start-stop of the yarn), this single-stage buffering method exposes systematic deficiencies. Because the yarn path from the traction point to the knitting point is long and the inertial mass is large, the tension adjustment action of the single buffer link lags seriously when dealing with high-frequency switching conditions, and it cannot respond in real time to the high and low yarn feeding requirements of the yarn bed that change alternately within a millisecond interval. At the same time, the transition link of the yarn in the delivery path lacks optimized guidance, which is prone to friction loss and tension fluctuation. In addition, the functional steps (such as traction, buffering, and guidance) in the existing method are often relatively independent, lacking a coordinated control mechanism, making it difficult to achieve stable tension of the yarn from introduction to knitting. These problems result in defects such as inaccurate yarn feeding, pattern misplacement, or yarn breakage when implementing high-frequency switching knitting with the existing yarn feeding method, which restricts the improvement of production efficiency and product quality of the flat knitting machine. SUMMARY

[0003] The purpose of the present application is to provide a yarn feeding method for a flat knitting machine, which improves the stability of yarn tension.

[0004] The present application is achieved by the following technical solutions.

[0005] A yarn feeding method for a flat knitting machine, comprising the following steps implemented in sequence:

[0006] a traction step of pulling the yarn by a traction mechanism;

[0007] a main buffering step of performing primary buffering on the yarn by a main buffer close to the downstream of the traction mechanism, the main buffer always applying a first tensioning force upward to the yarn guided thereby through a yarn guiding portion thereof;

[0008] a secondary buffering step of performing secondary buffering on the yarn by a secondary buffer close to the upstream of the yarn nozzle, the secondary buffer always applying a second tensioning force upward to the yarn guided thereby through a yarn guiding portion thereof;

[0009] a yarn feeding step of guiding the buffered yarn to the yarn bed through the yarn nozzle;

[0010] a knitting step of knitting the yarn provided by the yarn nozzle by the yarn bed.

[0011] As a further improvement of the present application, it further comprises:

[0012] The thread guiding step: guiding the yarn sent from the yarn source through the thread guiding part of the thread guide rod and sending it to the traction mechanism.

[0013] As a further improvement of the present application, it further comprises:

[0014] The first guiding step: guiding the yarn between the traction step and the main buffering step, and through the first thread guide wheel;

[0015] The second guiding step: guiding the yarn between the main buffering step and the auxiliary buffering step, and through the second thread guide wheel.

[0016] As a further improvement of the present application, in the thread guiding step, the yarn is controlled to pass through the thread guiding part of the thread guide rod in a path of first lifting and then sinking;

[0017] In the first guiding step, the yarn is controlled to pass through the first thread guide wheel in a path of first lifting and then sinking;

[0018] In the second guiding step, the yarn is controlled to pass through the second thread guide wheel in a path of first sinking and then translation.

[0019] As a further improvement of the present application, the main buffering member is powered by a driver to drive the thread guiding part to exert a first tension force of lifting on the yarn, and the size of the first tension force is adjusted by controlling the driver.

[0020] As a further improvement of the present application, the auxiliary buffering member is powered by a resilient member to drive the thread guiding part to exert a second tension force of lifting on the yarn.

[0021] As a further improvement of the present application, the size of the first tension force exerted by the main buffering member and the size of the second tension force exerted by the auxiliary buffering member are controlled so that the first tension force is greater than the second tension force.

[0022] As a further improvement of the present application, it further comprises:

[0023] The detection and adjustment step: detecting the height of the thread guiding part of the main buffering member by the detector, and adjusting the traction speed of the traction mechanism according to the detected height information.

[0024] As a further improvement of the present application, in the weaving step, the high-frequency alternating switching between the high-yarn feeding state and the low-yarn feeding state is alternately switched when the yarn bed weaves.

[0025] As a further improvement of the present application, the interval time of the high-frequency alternating switching is 5ms to 50ms.

[0026] The beneficial effects of the present application:

[0027] By introducing the cooperative timing operation of the main buffering step and the auxiliary buffering step, the problem of response lag and insufficient tension control precision of the traditional single-stage buffering method in long-path yarn conveying is effectively solved, the tension stability is improved through process optimization, yarn breakage and knitting defects are reduced, the adaptability of the flat knitting machine to complex processes and the production efficiency are enhanced, and the controllability of the whole process from yarn introduction to knitting forming is improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] The preferred embodiments of the present application will be described in detail below with the help of the accompanying drawings, which are intended to help understand the purposes and advantages of the present application, in which:

[0029] Figure 1 is a structural schematic diagram of a flat knitting machine;

[0030] Figure 2 is a display diagram of a yarn path in a flat knitting machine;

[0031] Figure 3 is a schematic diagram of a traction mechanism and a main buffer;

[0032] Figure 4 is a schematic diagram of a yarn nozzle and an auxiliary buffer;

[0033] Figure 5 is a schematic diagram of the steps of a yarn feeding method. DETAILED DESCRIPTION

[0034] The present application will be further described in detail below according to the drawings and embodiments.

[0035] In this specification, the orientation terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or possibly mentioned are defined with respect to the structure shown in the drawings, and the words "inner" and "outer" refer to the direction towards or away from the geometric center of a particular component, which are relative concepts, so they can change accordingly according to their different positions, different use states. Therefore, these or other orientation terms should not be interpreted as restrictive terms.

[0036] The present embodiment shows a yarn feeding method of a flat knitting machine, referring to Figures 1-5 The method includes traction step, main buffering step, auxiliary buffering step, yarn feeding step and knitting step implemented in sequence.

[0037] In the traction step, the yarn a is pulled at a controllable speed by the traction mechanism 3 composed of the driving wheel 31 and the driven wheel 32, to ensure stable output of the yarn a from the yarn source.

[0038] In the main buffering step, the yarn a is initially buffered by the main buffer 4 arranged downstream of the traction mechanism 3. The main buffer 4 has a guide section 41, which always applies an upward first tension force when the yarn a passes through, in order to absorb macroscopic changes in the flow rate of the yarn a.

[0039] In the secondary buffering step, the yarn a is further buffered by the secondary buffer 5 arranged upstream of the yarn feeder 6. The secondary buffer 5 also has a guide section 51 and always applies an upward second tension to handle local tension fluctuations near the yarn feeder 6.

[0040] In the yarn feeding step, the yarn feeder 6 guides the buffered yarn a and precisely delivers it to the designated position on the yarn bed 7.

[0041] Finally, in the weaving step, the yarn bed 7 (including the needle bed and the looping mechanism) weaves the provided yarn a to form a fabric.

[0042] The yarn feeding method in this embodiment forms a complete yarn a processing flow through these sequentially connected steps. The coordinated implementation of the main buffering step and the secondary buffering step constitutes a layered buffering mechanism: when the traction mechanism 3 accelerates, causing an increase in the demand for yarn a, the main buffering step quickly absorbs the excess yarn a through its tension force to prevent slack; the secondary buffering step operates synchronously to compensate for downstream tension and ensure uniform delivery of yarn a. When the traction mechanism 3 decelerates or the yarn bed 7 switches to a low-demand state, the main buffering step releases the stored yarn a, and the secondary buffering step maintains local tension stability. This staged buffering method decomposes the tension management of long-path yarn a into two shorter segments, significantly reducing the influence of inertia and enabling the system to maintain a rapid response even under high-frequency switching conditions. By transforming the product structure into method steps, this embodiment highlights the temporality and synergistic effect of the operation process. The main buffering step focuses on global tension adjustment, while the secondary buffering step handles micro-fluctuations. The two share the load, thereby improving the tension control accuracy and system reliability, making it particularly suitable for complex weaving processes that require precise yarn feeding.

[0043] The yarn feeding method of this embodiment also includes a yarn take-up step, which is performed before the traction step. In the yarn take-up step, the yarn a fed from the yarn a source 1 (such as a yarn bobbin) is guided by the guide wire 21 of the take-up lever 2 and smoothly fed to the traction mechanism 3. The take-up lever 2 is configured as a rod-shaped structure with a certain degree of elasticity, and its guide wire 21 is formed by bending at the end of the rod-shaped structure, used to smoothly guide the yarn a from the yarn a source 1 to the entrance of the traction mechanism 3. The design of the take-up lever 2 allows it to maintain a certain tension through its elasticity, applying a slight tension force to the yarn a, ensuring that the yarn a does not loosen or become tangled in the free section. This step, performed before the traction step, provides initial guidance and stabilization for the entire yarn feeding process, preventing the yarn a from becoming tangled or loose in the free section, thus laying the foundation for subsequent precise feeding.

[0044] The yarn feeding method of this embodiment also includes a first guiding step and a second guiding step. The first guiding step is implemented between the traction step and the main buffering step, guiding the yarn a through the first guide wheel s1; the second guiding step is implemented between the main buffering step and the secondary buffering step, guiding the yarn a through the second guide wheel s2. Both the first guide wheel s1 and the second guide wheel s2 are rotatable pulleys mounted on a fixed shaft, and their bearing structure ensures smooth rolling. In actual operation, after the yarn a is output from the traction mechanism 3, it is turned via the first guide wheel s1 in the first guiding step and smoothly enters the main buffering step; subsequently, the yarn a, after being processed in the main buffering step, transitions to the secondary buffering step via the second guide wheel s2 in the second guiding step. These guiding steps convert the sliding friction between the yarn a and the components into rolling friction, significantly reducing wear and energy loss. Through staged guidance, the method ensures path optimization for the yarn a at key transition points (such as between the main and secondary buffer components 5), avoiding stress concentration caused by abrupt angle changes, thereby maintaining tension uniformity and supporting high-speed operation.

[0045] In this embodiment, based on the consideration of fine control of yarn path dynamics, the yarn feeding method defines the path trajectory of yarn a in the take-up step, the first guiding step, and the second guiding step. In the take-up step, yarn a is controlled to pass through the guide section 21 of the take-up lever 2 in a path that first rises and then sinks. That is, after being drawn from the yarn source, yarn a first rises and passes through the high point of the guide section 21, and then naturally sinks towards the traction mechanism 3, using gravity to eliminate initial slack. In the first guiding step, yarn a is controlled to pass through the first guide wheel s1 in a path that first rises and then sinks. That is, yarn a first rises and passes through the high point of the guide wheel from the outlet of the traction mechanism 3, and then sinks into the main buffer step. This helps to pre-tighten yarn a on the traction mechanism 3 side. In the second guiding step, yarn a is controlled to pass through the second guide wheel s2 in a path that first sinks and then moves horizontally. That is, yarn a first sinks and passes through the low point of the guide wheel from the outlet of the main buffer step, and then moves approximately horizontally into the secondary buffer step, using gravity to maintain natural tension. This path sequence optimizes the movement trajectory of yarn a, causing yarn a to undergo a tension-relaxation cycle at key nodes, dynamically balancing the tension. By controlling the path trajectory, this method reduces dependence on external driving forces, utilizes natural forces (such as gravity) to assist in tension maintenance, reduces energy consumption, and enhances the system's adaptability to speed changes, ensuring the stability and efficiency of the conveying process.

[0046] In this embodiment, to improve the controllability and adjustment flexibility of the main buffering step, a driver provides power to the main buffer 4, driving its guide wire 41 to apply an upward first tension force to the yarn a. The magnitude of the first tension force is adjusted by controlling the driver. The main buffer 4 is a rod-shaped structure with a pivot point, allowing it to swing up and down. The guide wire 41 of the main buffer 4 is a ring-shaped structure located at one end of the main buffer 4. The driver can be an electric actuator (such as a torque motor), which drives the main buffer 4 to swing up and down around the pivot point via a connecting rod or direct connection. During operation, the driver adjusts the output force in real time according to the tension requirements of the yarn a or external signals (such as detector feedback), thereby changing the magnitude of the first tension force. For example, in a high yarn feed state, the driver increases the output, increasing the upward amplitude of the main buffer 4 to absorb more yarn a; in a low yarn feed state, the output decreases, releasing the yarn a. This dynamic adjustment allows the main buffering step to precisely match the weaving requirements, improving the method's adaptability. By using a drive for control, the method achieves active tension management, avoiding the lag problem of traditional mechanical methods. Especially in high-frequency switching, the drive's rapid response ensures instantaneous tension adjustment, enhancing the reliability of the method.

[0047] In this embodiment, to simplify the implementation of the secondary buffering step and ensure its response speed, the secondary buffering member 5 is powered by an elastic element 52 to drive its guide wire portion 51 to apply an upward second tension force to the yarn a. The elastic element 52 can be a spring, which generates a continuous restoring force through elastic deformation. In operation, as the yarn a passes through, the secondary buffering member 5 automatically maintains the upward trend by relying on the power of the elastic element 52, applying a stable second tension force to the yarn a. This step requires no external power source, has a simple structure, and can quickly respond to small changes in the length of the yarn a, such as when the yarn feeder 6 starts or stops. The elastic element 52 absorbs vibration through expansion and contraction, preventing sudden tension changes. This method design reduces system complexity, improves the economy and reliability of the secondary buffering step, and its synergy with the main buffering step forms a complementary mechanism of "active adjustment + passive buffering," optimizing the overall tension control effect. More specifically regarding the yarn feeder 6 and the secondary buffer 5, the yarn feeder 6 is located at the lower part of the yarn feeder frame 61, and the upper part of the yarn feeder frame 61 is fitted with a torsion spring as an elastic element 52 via a mounting base 62. The secondary buffer 5 is a rod-shaped structure formed by extending one end of the torsion spring outward, and the guide wire portion 51 of the secondary buffer 5 is formed by bending the rod-shaped structure multiple times.

[0048] In this embodiment, based on considerations of tension gradient optimization and load distribution, the magnitude of the first tension applied by the main buffer 4 and the second tension applied by the secondary buffer 5 are controlled so that the first tension is greater than the second tension. During operation, the first tension of the main buffer step is stronger, undertaking the main tension adjustment task; the second tension of the secondary buffer step is weaker, responsible for local smoothing. This tension difference causes the tension of yarn a to exhibit a gradient distribution from high to low during the conveying process from the traction mechanism 3 to the yarn feeder 6, avoiding tension concentration.

[0049] The yarn feeding method in this embodiment also includes a detection and adjustment step: the height of the guide wire 41 of the main buffer 4 is detected by a detector, and the traction speed of the traction mechanism 3 is adjusted according to the detected height information. The detector is set as a position sensor (such as a photoelectric sensor or encoder), angle sensor or displacement sensor, which monitors the height of the guide wire 41 in real time; the control system adjusts the speed of the traction mechanism 3 according to the height data (e.g., a higher height indicates that the yarn a is slack, and a lower height indicates that it is too tight). This step is linked with the main buffer step and the traction step to form a closed-loop control. For example, when the height of the guide wire 41 is detected to rise, the traction speed is reduced; when the height is detected to fall, the traction speed is increased. This method enables the yarn feeding process to have adaptive capabilities, and can respond to changes in the tension of the yarn a in real time, ensuring the accuracy of yarn feeding. Especially in high-frequency switching, the detection and adjustment step provides rapid feedback, avoiding the lag of traditional open-loop control and improving the accuracy and efficiency of the method.

[0050] In this embodiment, during the weaving step, the yarn bed 7 is controlled to alternately switch between a high yarn feed rate state and a low yarn feed rate state at high frequency during weaving. The high yarn feed rate state corresponds to the weaving stage where the demand for yarn a is high (such as a dense pattern area), and the low yarn feed rate state corresponds to the stage where the demand is low (such as a sparse area).

[0051] It is important to note that this high-frequency switching is characteristic of complex weaving techniques such as sesame-dot jacquard. In these techniques, to create a dense, alternating dot pattern, the yarn bed 7 and its corresponding yarn feeder 6 need to start and stop at an extremely high frequency to rapidly switch between different yarns a or weaving actions. Under these conditions, the feeding and stopping of yarn a must be precisely synchronized with the switching of the yarn bed 7; any slight asynchrony can lead to defects such as pattern misalignment, yarn a accumulation, or breakage.

[0052] In existing technologies, a single buffer rod (or swing rod) is typically installed downstream of the traction mechanism 3. Driven by a torque motor, it applies tension to yarn a. The buffer rod needs to manage and control all yarn a from its own position, through the entire conveying path, to the yarn feeder 6, and finally to the weaving point of the yarn bed 7. This section of yarn a is relatively long and has a certain mass, thus generating significant inertia. When the yarn bed 7 switches frequently, for example, after a start and stop command with an extremely short interval (e.g., milliseconds), the yarn bed 7 can respond quickly, but the yarn a will continue to move or tend to move due to inertia. At this time, the buffer rod needs to overcome the inertia of the entire long section of yarn a to complete the lifting (yarn storage) or lowering (yarn release) action to adjust the tension. Due to the large total amount and inertia of the yarn a to be controlled, the physical movement (lifting / lowering) of the buffer rod will inevitably lag, unable to keep up with the high-frequency switching rhythm of the yarn bed 7. This lag directly causes the feedback signal (such as the position of the buffer rod) received by the speed regulation system of the traction mechanism 3 to be delayed, thus rendering the speed regulation itself ineffective. The end result is that when the yarn bed 7 needs yarn a, yarn a may not be delivered in time (the buffer rod sinks and releases yarn in time); when the yarn bed 7 stops, excess yarn a may be delivered (the buffer rod lifts and stores yarn in time), causing yarn a to be slack and uneven in tension, which seriously affects the implementation effect of weaving processes that require precise yarn supply, such as sesame jacquard, resulting in unclear patterns, mixed colors, or uneven fabric surfaces.

[0053] In this embodiment, the layered buffering system constructed by the main buffer 4 and the secondary buffer 5 fundamentally improves the dynamic response performance of the system under high-frequency switching conditions. The main buffer 4 is located downstream of the traction mechanism 3 and is mainly responsible for handling macroscopic yarn a flow changes from the traction mechanism 3 side; while the secondary buffer 5 is located upstream of the yarn feeder 6 and focuses on handling local yarn a tension fluctuations near the yarn feeder 6 and closer to the weaving point. This architecture effectively divides the "long path" of yarn a from the traction mechanism 3 to the yarn bed 7, which was originally controlled by a single buffer rod, into two relatively short segments: one segment from the traction mechanism 3 to the upstream side of the secondary buffer 5, mainly handled by the main buffer 4; and the other segment from the secondary buffer 5 to the yarn feeder 6 and the yarn bed 7, mainly handled by the secondary buffer 5. The length and total mass of yarn a that need to be controlled in each segment are significantly reduced, thereby greatly reducing the inertial effect of each yarn a segment.

[0054] When the yarn bed 7 alternates frequently, at the instant it switches from a stopped state to a working state, the yarn bed 7 begins weaving, requiring yarn a. At this time, the secondary buffer 5, due to its extremely close position to the yarn feeder 6, can almost instantaneously sense the decrease in yarn a tension and immediately, through the upward tensioning action of its guide section 51, quickly provides a portion of yarn a locally to meet the initial needs of the weaving point. Almost simultaneously, the detector at the main buffer 4 detects a change in the height of its guide section 41 (a downward trend) and quickly feeds this signal back to the control system, which then instructs the traction mechanism 3 to accelerate the delivery of yarn a. Since the amount of yarn a that the main buffer 4 needs to compensate for is limited to the section between it and the secondary buffer 5, its inertia is small, and its response speed is faster. Conversely, at the instant the yarn bed 7 switches from a working state to a stopped state, the yarn supply demand stops. The secondary buffer 5 can respond quickly, tightening the small amount of yarn a downstream of it through its upward force, preventing it from continuing to rush towards the yarn bed 7 due to inertia and causing slack. The main buffer 4 works in conjunction to absorb excess yarn a from upstream. Since the secondary buffer 5 has already taken on the task of quickly tightening the downstream yarn a, the amount of yarn a that the main buffer 4 needs to absorb is relatively reduced, the action is faster, and the lag is greatly reduced.

[0055] The detector configured in the main buffer 4 continuously monitors its height, providing real-time and accurate feedback for the speed adjustment of the traction mechanism 3. This allows the traction speed to be quickly and precisely matched with the actual needs of the yarn bed 7 (indirectly reflected through the state of the buffer system). The secondary buffer 5 is powered by an elastic element, and its response is inherently rapid, making it ideal for handling high-frequency, minute tension fluctuations. The synergistic and complementary operation of the main buffer 4 and the secondary buffer 5 ensures stable yarn tension and timely yarn supply even with extremely short switching intervals. Therefore, the flat knitting machine of this embodiment can significantly improve the implementation effect of knitting processes such as sesame jacquard that require high-frequency switching, ensuring accurate and clear patterns, high fabric quality, and reducing the risk of yarn breakage and downtime due to tension loss of control.

[0056] In this embodiment, to accurately define the operating parameters of high-frequency switching, the interval time for high-frequency alternating switching is set to 5ms to 50ms. This time range covers the requirements of most high-speed weaving processes. For example, in sesame dot jacquard, the start-stop frequency of the yarn bed 7 is extremely high, with intervals as short as milliseconds.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A yarn feeding method for a flat knitting machine, characterized in that, comprising sequentially implemented: a pulling step of pulling the yarn by a pulling mechanism; a main buffering step of primarily buffering the yarn by a main buffer located downstream of the pulling mechanism, the main buffer always applying a first tension force of lifting to the yarn guided therethrough by a wire guide thereof; a secondary buffering step of secondarily buffering the yarn by a secondary buffer located upstream of the yarn nozzle, the secondary buffer always applying a second tension force of lifting to the yarn guided therethrough by a wire guide thereof; a feeding step of feeding the buffered yarn to a yarn bed by the yarn nozzle; a weaving step of weaving the yarn provided by the yarn nozzle by the yarn bed.

2. The yarn feeding method according to claim 1, characterized by further comprising: a thread lifting step of guiding the yarn sent from a yarn source to the pulling mechanism by a wire guide of a thread lifting rod.

3. The yarn feeding method according to claim 2, characterized in that, further comprising: a first guiding step of guiding the yarn between the pulling step and the main buffering step by a first wire guide wheel; a second guiding step of guiding the yarn between the main buffering step and the secondary buffering step by a second wire guide wheel.

4. The yarn feeding method according to claim 3, characterized by in the thread lifting step, the yarn is controlled to pass through the wire guide of the thread lifting rod in a path of lifting first and then sinking; in the first guiding step, the yarn is controlled to pass through the first wire guide wheel in a path of lifting first and then sinking; in the second guiding step, the yarn is controlled to pass through the second wire guide wheel in a path of sinking first and then translating.

5. The yarn feeding method according to claim 1, characterized by the main buffer is powered by a driver to drive the wire guide thereof to apply the first tension force of lifting to the yarn, and the first tension force is adjusted by controlling the driver.

6. The yarn feeding method according to claim 1, characterized by the secondary buffer is powered by an elastic member to drive the wire guide thereof to apply the second tension force of lifting to the yarn.

7. The yarn feeding method according to claim 1, wherein the first tension force applied by the main buffer and the second tension force applied by the secondary buffer are controlled such that the first tension force is greater than the second tension force.

8. The yarn feeding method according to any one of claims 1 to 7, characterized in that, further comprising: a detection and adjustment step of detecting the height of the wire guide of the main buffer by a detector, and adjusting the pulling speed of the pulling mechanism according to the detected height information.

9. The yarn feeding method according to claim 8, characterized in that, in the weaving step, the yarn bed alternately switches between a high yarn feeding state and a low yarn feeding state at a high frequency.

10. The yarn feeding method according to claim 9, characterized by the interval time of the high frequency alternation is 5ms to 50ms.

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