Knitting device for dynamically adjusting surface knitting angle of annular knitting body

Abstract

The invention relates to a knitting device for dynamically adjusting a knitting angle on the surface of an annular knitted body. The knitting device comprises a spool module, a special-shaped guide ring and a dynamic eccentric mandrel, wherein the spool modules are uniformly arranged on the concentric circumference of the plane of the spool of the annular knitting machine; the special-shaped guide ring is positioned on one side of the spool module, and the center of the special-shaped guide ring is coaxial with the center of a spool plane of the annular knitting machine; an elliptical weaving ring is arranged on the special-shaped guide ring; the dynamic eccentric mandrel is located on one side of the special-shaped guide ring, and the position of the dynamic eccentric mandrel relative to the center of the special-shaped guide ring can be dynamically adjusted. Through the synergistic effect of the special-shaped guide ring and the dynamic eccentric mandrel, the falling point distance of fibers in the weaving process is dynamically adjusted, so that the weaving angle distribution is optimized, bending wrinkles of a cylindrical composite material preformed part are reduced, and the situation that due to the defect, friction, sliding and other interaction between the fibers are caused, and durability is reduced is avoided.

Description

Technical field

[0001] The invention relates to a component device of an annular braiding machine, in particular to a braiding device for dynamically adjusting the braiding angle on the surface of an annular braided body, and belongs to the technical field of composite material preparation. [Background Technology]

[0002] A cylindrical composite preform rotational braid generally requires tightly wound fibers to form a braid. However, the preform produced by such braiding may form wrinkles during bending.

[0003] Wrinkling is a serious defect. During composite manufacturing, wrinkles can easily form due to changes in fiber orientation, especially in curved sections. For example, during vacuum-assisted resin infusion, when a braided preform is bent, the braid angle on the compression side increases, while the braid angle on the tension side decreases. This change in fiber orientation can easily cause wrinkles. During bending, the inner side of the braided tube is subjected to compression and the outer side to tension. When these forces exceed certain limits, they can cause fiber shear and slippage, leading to wrinkle formation. Furthermore, during the resin infusion and curing processes, resin flow and curing shrinkage can also exert additional forces on the fibers, further exacerbating wrinkle formation.

[0004] For example, wrinkles during the production process can cause voids in curved areas, which in turn can reduce the strength and stiffness of composite materials, impacting their load-bearing capacity and durability. Wrinkles can also make the composite surface uneven, affecting the product's appearance and quality, and can lead to dimensional deviations, affecting the precision of fit with other components. Fiber accumulation and stress concentration in wrinkles can become the initiation source of fatigue cracks, reducing the composite's fatigue life and increasing the risk of fatigue failure. Furthermore, resin accumulation and fiber exposure in wrinkles can reduce the composite's corrosion resistance, making it susceptible to erosion by environmental media.

[0005] The existing circular braiding machine usually adopts a fixed core shaft and a homogeneous braiding ring, which causes a sudden change in the fiber angle when bending, which easily leads to the above-mentioned slippage and wrinkling problems; while increasing the braiding tension to suppress wrinkles easily leads to fiber breakage.

[0006] Reducing wrinkles can prevent the reduction in composite material strength and stiffness caused by wrinkles, thereby improving its load-bearing capacity and durability. Reducing wrinkles also smooths the composite surface, improving the product's appearance and quality, and reduces dimensional deviation, ensuring good fit with other components. Avoiding fiber accumulation and stress concentration in wrinkles reduces the initiation of fatigue cracks, thereby increasing the fatigue life of the composite. Reducing resin accumulation and fiber exposure improves the composite's corrosion resistance, making it less susceptible to environmental media.

[0007] Therefore, in order to solve the above problems, it is necessary to provide an innovative braiding device that can dynamically adjust the braiding angle on the surface of the annular braided body to overcome the above defects in the prior art. [Summary of the invention]

[0008] The object of the present invention is to provide a weaving device for dynamically adjusting the weaving angle of the surface of an annular braided body, which dynamically adjusts the landing distance of the fibers during the weaving process through the synergistic action of a special-shaped guide ring and a dynamic eccentric core shaft, thereby optimizing the weaving angle distribution, reducing the bending and wrinkling of the cylindrical composite material preform, and preventing the durability from being reduced due to the interaction of friction, slippage, etc. between the fibers caused by such defects.

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a weaving device for dynamically adjusting the weaving angle of the surface of a circular braided body, which includes a yarn barrel module, a special-shaped guide ring and a dynamic eccentric core shaft; wherein, the yarn barrel module is evenly arranged on the concentric circles of the plane of the circular braiding machine axis; the special-shaped guide ring is located on one side of the yarn barrel module, and its center is coaxial with the center of the plane of the circular braiding machine axis; an elliptical weaving ring is provided on the special-shaped guide ring; the dynamic eccentric core shaft is located on one side of the special-shaped guide ring, and it can dynamically adjust its position relative to the center of the special-shaped guide ring.

[0010] The braiding device for dynamically adjusting the braiding angle on the surface of an annular braided body of the present invention further comprises: a ratio of the major axis a to the minor axis b of the elliptical braiding ring is 1.2 to 3.0.

[0011] The braiding device for dynamically adjusting the braiding angle on the surface of an annular braided body of the present invention further comprises: the special-shaped guide ring is made of titanium alloy, and a shape memory alloy is implanted therein.

[0012] The weaving device for dynamically adjusting the weaving angle on the surface of the annular braided body of the present invention is further as follows: the dynamic eccentric core shaft is driven by a six-degree-of-freedom robotic arm, and the six-degree-of-freedom robotic arm can dynamically adjust the position of the core shaft relative to the center of the special-shaped guide ring, as well as the withdrawal speed of the core shaft, to achieve dynamic adjustment of the weaving angle.

[0013] The braiding device for dynamically adjusting the braiding angle of the annular braided body of the present invention further comprises: a specific method for dynamically adjusting the position of the core shaft relative to the center of the special-shaped guide ring is as follows: when the braided body enters the bending area for braiding, the manipulator drives the core shaft to deflect κ·e to the compression side. max , where κ is the real-time curvature of the braid, e max is the maximum eccentricity; at the same time, the mandrel pulling speed is reduced from the reference value v0 to 0.8v0; the stretching side is offset in the reverse direction and the pulling speed is increased to 1.2v0.

[0014] The braiding device for dynamically adjusting the braiding angle of the annular braided body surface of the present invention further comprises: a specific method for controlling the mandrel withdrawal speed is as follows: when the mandrel enters a high curvature section with a curvature κ>0.15mm-1, the pulling speed is increased to v'=v0(1+0.5κ), and the carrier rotation speed is reduced to ω'=ω0 / (1+0.3κ), and by maintaining v' / ω'≈C, where C is the tension equilibrium constant, the fiber tension fluctuation is ensured to be less than 5%; the eccentricity e is dynamically adjusted according to the real-time curvature: e=min(κ·K e ,e max ), where K e is the curvature compensation coefficient, which expands the braiding angle adjustment range from the conventional ±8° to ±18°.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The weaving device for dynamically adjusting the weaving angle of the surface of the annular weaving body of the present invention makes the distribution of fibers in different directions more reasonable by setting an elliptical weaving ring, thereby reducing wrinkles caused by changes in fiber orientation. Specifically, the use of a special-shaped guide ring can pre-adjust the angle of the fiber during the weaving process, so that in the subsequent bending process, the angle change of the fiber is more uniform, thereby reducing the formation of wrinkles; after bending, the sample using the elliptical weaving ring can suppress the change of the weaving angle on the compression side to a certain extent compared with the circular weaving ring, and the thickness of the special-shaped weaving ring sample is more uniform, which effectively reduces the formation of wrinkles.

[0017] 2. The weaving device for dynamically adjusting the weaving angle of the surface of the annular braided body of the present invention can change the angular distribution of the fibers in the circumferential direction of the weaving ring by setting a dynamic eccentric core shaft, so that during the bending process, the angle change of the fibers is more in line with actual needs and the formation of wrinkles is reduced; specifically, by adjusting the position of the core shaft, the angles and tensions of the fibers in different directions can be made more reasonable during the weaving process, thereby reducing the shearing and slippage of the fibers in the subsequent bending process and reducing the risk of wrinkle formation.

[0018] 3. The high-performance composite material preforms produced by the weaving device for dynamically adjusting the weaving angle of the surface of the annular braided body of the present invention are widely used in a variety of fields such as aerospace, rail transportation, wind power generation, automobile manufacturing, medical equipment, sporting goods, construction, and electronics, so as to meet the needs of different industries for composite materials with characteristics such as light weight, high strength, high temperature resistance, corrosion resistance, and high toughness.

Brief Description of the Drawings

[0019] Figure 1 It is a perspective view of a braiding device for dynamically adjusting the braiding angle on the surface of an annular braid according to the present invention.

[0020] Figure 2 yes Figure 1Front view of the fiber guide ring, showing the dynamic adjustment of the fiber path with the eccentric position of the mandrel.

[0021] Figure 3 yes Figure 1 side view.

[0022] Figure 4 This is a diagram of the braiding angle changes of special-shaped guide rings of different sizes, showing that the angle change of the compression side fiber is smoother under the special-shaped structure.

[0023] Figure 5 It is a schematic diagram of the axial gradient parameters of the dynamic eccentric mandrel, marking the eccentricity range (0-30mm) of each section that can be adjusted independently and its influence on the braiding angle.

[0024] Figure 6 This is an example diagram of a special-shaped guide ring.

[0025] Figure 7 This is an example diagram of a special-shaped guide ring in another embodiment. [Specific implementation method]

[0026] Please refer to the instruction manual Figure 1 To the attached Figure 7 As shown, the present invention is a braiding device for dynamically adjusting the braiding angle on the surface of an annular braided body, which is composed of several parts such as a yarn tube module 1, a special-shaped guide ring 2 and a dynamic eccentric core shaft 3.

[0027] The yarn drum modules 1 are evenly arranged on the concentric circumference of the circular braiding machine's bobbin plane 5. Each yarn drum contains a fiber bundle 4, which is guided through a shaped guide ring 2 for trajectory correction before being wound onto the core shaft to form a composite preform.

[0028] The special-shaped guide ring 2 is located on one side of the yarn tube module 1, and its center is coaxial with the center of the circular braiding machine bobbin plane 5. An elliptical braiding ring 21 is provided on the special-shaped guide ring 2. Using an elliptical braiding ring instead of a circular braiding ring for braiding can produce two different braiding angles on the large diameter and small diameter of the elliptical braiding ring 21. Due to the different distances from the elliptical braiding ring 21 to the braiding landing point on the core shaft, different braiding angles are achieved on the offset plane. The braid angles and the changes in the braid angles measured after bending these braids are optimized, because the braid angles on the tensile and compression sides are different from the angles along the neutral axis.

[0029] Furthermore, the ratio of the major axis a to the minor axis b of the elliptical braiding ring is 1.2 to 3.0, and the specific ratio is dynamically adjusted according to the target braiding angle. When the fiber 4 passes through the major axis endpoint of the ellipse, the radius of its motion trajectory increases to R_max = 1.2D (D is the reference diameter). At this time, according to the braiding angle formula α = arctan (v / ωr), it can be calculated that under the condition of constant core shaft pulling speed v, the increase in contact point radius r will directly lead to a 15%-22% reduction in the braiding angle. Conversely, when the fiber passes the minor axis endpoint, the trajectory radius is reduced to 0.8D, causing the braiding angle to increase by 18%-25% year-on-year, forming a periodic angle fluctuation.

[0030] In this embodiment, when the ratio a / b of the elliptical braiding loop is 1.5, the initial braiding angle is ±41° when braiding with the elliptical braiding loop, and the braiding angle on the compression side increases to approximately ±45° after bending. When using circular braiding loops, the initial braiding angle is ±45°, and the braiding angle on the compression side increases to approximately ±54° after bending. After bending, the average thickness of the samples using the elliptical braiding loop on the compression side is 0.75 mm, while the average thickness of the samples using the circular braiding loop on the compression side is 1.27 mm, resulting in a more uniform thickness and effectively reducing the formation of wrinkles.

[0031] In this embodiment, the profiled guide ring 2 is made of titanium alloy to reduce wear caused by fiber friction and lower inertia. It must withstand high temperatures (typically ≥200°C) during high-speed weaving or resin curing to avoid deformation or performance degradation. It also has a tensile strength of ≥500 MPa to ensure it remains stable under dynamic tension.

[0032] Shape memory alloy (SMA) is implanted in the special-shaped guide ring 2. When a special braiding angle requirement is detected, the long-axis ratio of the guide ring is continuously adjustable within the range of 1.05-1.25 through current excitation, and a dual control mechanism is formed in conjunction with the core shaft offset. Experiments have shown that this design further expands the dynamic adjustment range of the braiding angle to 15°-65°, and shortens the angle switching response time by 40%. The entire system is connected to the host computer via industrial Ethernet, supports the direct import of three-dimensional models and automatically generates motion trajectory parameters, and realizes fully automatic braiding of complex special-shaped components.

[0033] The dynamically eccentric mandrel 3 is located on one side of the shaped guide ring 2 and can dynamically adjust its position relative to the center of the shaped guide ring 2, that is, dynamically adjust the eccentric distance of the mandrel. In other words, the position offset of the mandrel 3 relative to the center of the guide ring 2 can be dynamically adjusted during the winding and extraction process of the mandrel 3.

[0034] The dynamic eccentric core shaft 3 is specifically driven by a six-degree-of-freedom robotic arm, which can dynamically adjust the position of the core shaft 3 relative to the center of the special-shaped guide ring 2 and the withdrawal speed of the core shaft 3 to achieve dynamic adjustment of the braiding angle.

[0035] Among them, the specific method of dynamically adjusting the position of the mandrel relative to the center of the special-shaped guide ring is as follows: when the braid enters the bending area for weaving, the robotic arm drives the mandrel to offset κ·emax toward the compression side, where κ is the real-time curvature of the braid and emax is the maximum eccentricity; at the same time, in conjunction with this offset action, the mandrel pulling speed is reduced from the reference value v0 to 0.8v0, and the fiber winding density is increased by reducing the axial stretching rate. Experimental data show that this strategy can increase the braiding angle on the inner side of the bend from the reference 45° to 58°±2°, and reduce the fiber slip rate by 37%. At the same time, the tensile side reduces the braiding angle to 32°±2° by reverse offset and increasing the pulling speed to 1.2v0, forming a gradient angle distribution.

[0036] Furthermore, the mandrel pulling speed and the carrier rotation speed are controlled inversely, that is, when the mandrel enters a high curvature bending section, the mandrel pulling speed is increased while the carrier rotation speed is reduced, and the fiber tension balance is maintained by a speed difference compensation algorithm; the eccentricity e increases or decreases with the change of curvature, further expanding the braiding angle adjustment range. Specifically. The specific control method of the mandrel withdrawal speed is: when the mandrel enters a high curvature section with a curvature κ>0.15mm-1, the pulling speed is increased to v'=v0(1+0.5κ), and the carrier rotation speed is reduced to ω'=ω0 / (1+0.3κ), and by maintaining v' / ω'≈C, C is the tension balance constant, ensuring that the fiber tension fluctuation is <5%; the eccentricity e is dynamically adjusted according to the real-time curvature: e=min(κ·K e ,e max ), where K e is the curvature compensation coefficient, which expands the braiding angle adjustment range from the conventional ±8° to ±18°.

[0037] In this embodiment, when the eccentricity of the dynamic eccentric mandrel 3 is 25 mm, the braiding angle on the compression side after bending increases from the initial ±41° to about ±45°, which is similar to the effect of the special-shaped braiding ring, thereby achieving the optimization of the local braiding angle. When braiding to the bending area of the preform, the robotic arm offsets the mandrel toward the compression side (such as e=20 mm) according to the preset model, while reducing the pumping speed (such as v=1 mm / s), and increasing the braiding angle in this area (±45°→±50°) to suppress fiber slippage. The tensile side simultaneously reduces the eccentricity (e=10 mm) and increases the pumping speed (v=3 mm / s), reduces the braiding angle (±45°→±40°), and reduces the tensile stress.

[0038] In summary, the present invention, by changing the shape of the braiding ring 21, makes the distribution of fibers in different directions more reasonable, thereby reducing wrinkles caused by changes in fiber orientation. Specifically, the use of a special-shaped braiding ring allows the fiber angle to be pre-adjusted during the braiding process, so that the fiber angle changes more evenly during the subsequent bending process, thereby reducing the formation of wrinkles. After bending, the sample using the special-shaped braiding ring can suppress the braiding angle change on the compression side to a certain extent compared to the circular braiding ring, and the thickness of the special-shaped braiding ring sample is more uniform, effectively reducing the formation of wrinkles.

[0039] An eccentric mandrel position can change the angular distribution of the fibers around the braiding ring, ensuring that the fiber angle changes during bending more accurately meet actual needs and reduce wrinkle formation. Specifically, by adjusting the mandrel position, the angles and tensions of the fibers in different directions can be more optimal during braiding, thereby reducing fiber shearing and slippage during subsequent bending, lowering the risk of wrinkle formation.

[0040] The above specific implementation methods are only preferred embodiments of this creation and are not intended to limit this creation. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this creation should be included in the scope of protection of this creation.

Claims

1. A braiding device for dynamically adjusting the braiding angle on the surface of an annular braid, characterized by: It includes a yarn barrel module, a special-shaped guide ring and a dynamic eccentric core shaft; wherein the yarn barrel module is evenly arranged on the concentric circles of the annular braiding machine's bobbin plane; the special-shaped guide ring is located on one side of the yarn barrel module, and its center is coaxial with the center of the annular braiding machine's bobbin plane; an elliptical braiding ring is provided on the special-shaped guide ring; the dynamic eccentric core shaft is located on one side of the special-shaped guide ring, and its position relative to the center of the special-shaped guide ring can be dynamically adjusted.

2. The braiding device for dynamically adjusting the braiding angle on the surface of an annular braid according to claim 1, characterized in that: The ratio of the major axis a to the minor axis b of the elliptical braided ring is 1.2 to 3.

0.

3. The braiding device for dynamically adjusting the braiding angle on the surface of an annular braid according to claim 1, characterized in that: The special-shaped guide ring is made of titanium alloy, and shape memory alloy is implanted therein.

4. The braiding device for dynamically adjusting the braiding angle of the annular braid according to claim 1, characterized in that: The dynamic eccentric mandrel is driven by a six-degree-of-freedom robotic arm, which can dynamically adjust the position of the mandrel relative to the center of the special-shaped guide ring and the withdrawal speed of the mandrel to achieve dynamic adjustment of the braiding angle.

5. The braiding device for dynamically adjusting the braiding angle on the surface of an annular braid according to claim 4, characterized in that: The specific method of dynamically adjusting the position of the core shaft relative to the center of the special-shaped guide ring is as follows: when the braid enters the bending area for braiding, the manipulator drives the core shaft to deflect to the compression side κ·e max , where κ is the real-time curvature of the braid, e max is the maximum eccentricity; at the same time, the mandrel pulling speed is reduced from the reference value v0 to 0.8v0; the stretching side is offset in the reverse direction and the pulling speed is increased to 1.2v0.

6. The braiding device for dynamically adjusting the braiding angle on the surface of an annular braid according to claim 5, characterized in that: The specific control method of the mandrel extraction speed is as follows: when the mandrel enters a high curvature section with a curvature κ>0.15mm-1, the pulling speed is increased to v'=v0(1+0.5κ), and the carrier rotation speed is reduced to ω'=ω0 / (1+0.3κ). By maintaining v' / ω'≈C, where C is the tension equilibrium constant, the fiber tension fluctuation is ensured to be less than 5%; the eccentricity e is dynamically adjusted according to the real-time curvature: e=min(κ·K e ,e max ), where K e is the curvature compensation coefficient, which expands the braiding angle adjustment range from the conventional ±8° to ±18°.

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