A forming device and process for an axially composite fiber pipe connected by warp and weft weaving

Abstract

The application relates to a forming device and process of an axially composite fiber pipe material woven and connected by warp and weft, and belongs to the technical field of composite material forming. The device comprises a multi-axial warp knitting mechanism, an impregnation mechanism, a pultrusion die, a modular core mold system and a traction cutting mechanism arranged downstream of the pultrusion die and used for traction of the solidified pipe material and cutting of the pipe material according to a set length. The multi-axial warp knitting mechanism directly knits 0-degree axial yarn, + / - theta-degree woven yarn and 90-degree hoop yarn in a tubular space, changes a traditional process of "plane weaving -> cutting -> winding", realizes integrated jointless forming of a tubular preform, eliminates joints and lap joint areas, realizes continuous fiber without breakage, and significantly improves interlayer bonding strength.

Description

Technical Field

[0001] This application belongs to the field of composite material molding technology, specifically relating to a molding device and process for an axial composite fiber tube with warp and weft braided connection. Background Technology

[0002] Fiber-reinforced composite pipes are widely used due to their high strength, corrosion resistance, and design flexibility. The processing of composite fiber pipes involves a series of steps, including woven fabric preforms, resin impregnation, and pultrusion molding.

[0003] In the existing technology, the fabric preform is made of planar fabric that has undergone secondary processing such as cutting and winding, which results in seams in the fabric preform. This causes the reinforcing fibers to be discontinuously distributed in the circumferential or axial direction of the pipe, lacking integrity, resulting in low pipe strength and affecting the reliability of use.

[0004] Therefore, there is an urgent need to develop a device and process for integrated multiaxial braiding of tubular structures. Summary of the Invention

[0005] To solve the above problems, the technical solution adopted in this application is: The first aspect of this application provides an axial composite fiber tube forming device with warp and weft braided connections, comprising: Multiaxial warp knitting mechanism is used to directly knit in a tubular space to form a multiaxial integrated tubular fabric preform containing 0-degree axial yarn, ±θ-degree knitting yarn and 90-degree circumferential yarn; The impregnation mechanism, located downstream of the multi-axial warp knitting mechanism, includes a resin impregnation tank and a vacuum-assisted impregnation device. The vacuum-assisted impregnation device is connected to the impregnation tank and is used to draw a vacuum during the impregnation process to remove air bubbles. A pultrusion die is located downstream of the impregnation mechanism and is provided with a preheating zone, a gelation zone, a curing zone and a cooling zone in sequence along the axial direction, for heating and curing the impregnated tubular preform. A modular core mold system extends through the multi-axial warp knitting mechanism, the impregnation mechanism, and the pultrusion die; A traction cutting mechanism is located downstream of the pultrusion die and is used to pull the cured pipe and cut it to a set length.

[0006] Furthermore, the multi-axial warp knitting mechanism includes: A circular yarn frame, comprising multiple sets of yarn spindles evenly arranged along its circumference, the circular yarn frame including: The inner layer spindle group is used to supply 0-degree axial yarn, and the spindles in the inner layer spindle group are arranged parallel to each other along the axial direction. The middle layer spindle group is used to supply ±θ degree weaving yarn. The spindles in the middle layer spindle group are arranged at ±θ degree angles relative to the axial direction, and the θ angle is adjustable in the range of 15 to 75 degrees. The outer layer spindle group is used to supply 90-degree circumferential yarn, and the spindles in the outer layer spindle group are arranged in a circumferential direction; it is used to supply 0-degree axial yarn, ±θ-degree braided yarn and 90-degree circumferential yarn; A tubular looping mechanism, located downstream of the annular yarn frame, includes composite needles, comb bars, and sinkers arranged in a circumferential direction, used to bind yarns in each direction into a seamless integrated tubular fabric through a warp-knitted loop structure. A multi-layer weft laying device is set at different radial ring positions of the annular yarn frame, including at least 3 independently controlled weft laying trolleys. Each layer of weft laying trolleys is arranged in layers along the thickness direction of the tubular fabric and can rotate relative to each other around the axis of the tubular fabric. The weft yarn layers of adjacent weft laying trolleys form staggered overlaps with a staggered spacing of 1 to 5 loops in the longitudinal direction, so that the weft yarns of each layer are staggered in the thickness direction and bound by the warp knitting loops passing through the thickness direction. A pull-and-wind mechanism is located downstream of the tubular coiling mechanism and is used to continuously pull out the woven tubular fabric along the axial direction. In the tubular looping mechanism, the composite needle is a hook needle arranged circumferentially along the annular needle bed, the guide bar is a yarn guide bar arranged circumferentially along the annular needle bed, and the sinker is a sinker plate arranged circumferentially along the annular needle bed. The hook needle, the guide bar, and the sinker plate move in coordination to bind the 0-degree axial yarn, ±θ-degree knitting yarn, and 90-degree circumferential yarn into a warp-knitted loop structure.

[0007] Furthermore, the middle layer spindle group is provided with a knitting angle adjustment mechanism, the knitting angle adjustment mechanism including: An angle adjustment disc is installed on the spindle carrier of the middle layer spindle group; A servo motor drives the angle adjustment disk to rotate in order to change the yarn lead-out angle; An angle encoder is used to detect and provide feedback on the actual weaving angle of the ±θ degree woven yarn in real time, so that the deviation between the actual weaving angle and the set value is controlled within ±1 degree.

[0008] Furthermore, the modular core mold system includes: The core mold body is composed of multiple core modules spliced ​​along the axial direction, and the core modules are connected by a conical surface fit. The spiral guide groove is formed on the outer surface of the core mold body. It is a spiral groove that extends continuously along the outer surface of the core mold. The groove depth is 0.5mm to 3mm and the pitch is 10mm to 50mm. It is used to guide the resin to flow evenly in the axial and circumferential directions during the impregnation process.

[0009] Furthermore, the impregnation tank of the impregnation mechanism is an open impregnation tank, and a guide plate is provided in the tank to guide the resin flow; the impregnation mechanism also includes a resin circulation temperature control system to control the resin temperature in the impregnation tank between 20°C and 60°C.

[0010] Furthermore, in the pultrusion die, the temperature of the preheating zone is 80℃~120℃, the temperature of the gelation zone is 120℃~180℃, the temperature of the curing zone is 160℃~220℃, and the temperature of the cooling zone is 40℃~80℃; a heat insulation section is provided between each temperature zone.

[0011] The second aspect of this application provides a forming process for axial composite fiber tubing with warp and weft braiding, using the aforementioned axial composite fiber tubing forming device with warp and weft braiding, including the following steps: S1: Tubular Multiaxial Warp Knitting Forming Steps Within a tubular space, 0-degree axial yarn, ±θ-degree braided yarn, and 90-degree circumferential yarn are simultaneously woven using a multi-axial warp knitting mechanism to form a seamless integrated tubular fabric prefabricated body. Specifically, the 0-degree axial yarn is inserted parallel to the tube's axis, the ±θ-degree braided yarn interweaves at a ±θ-degree angle relative to the axis, and the 90-degree circumferential yarn is laid circumferentially along the tube. The yarns in each direction are bound together by a warp-knitted loop structure. At least three independently controlled weft-laying carriages are used for multi-layer weft laying. The weft yarn layers of adjacent weft-laying carriages form staggered overlaps with a staggered spacing of 1 to 5 loops, ensuring that the weft yarns of each layer are staggered in the thickness direction and bound together by warp-knitted loops that penetrate the thickness direction. S2: Continuous traction steps The woven tubular fabric preform is continuously pulled along the modular core mold system to the impregnation mechanism by the traction and winding mechanism. S3: Vacuum-assisted impregnation step Under the negative pressure environment provided by the vacuum-assisted impregnation device, the tubular fabric preform is introduced into the impregnation tank for resin impregnation; during the impregnation process, the resin flows uniformly along the axial and circumferential directions along the spiral guide groove on the outer surface of the modular core mold system, so as to achieve uniform distribution of resin in the tube wall thickness direction and circumferential direction. S4: Pultrusion curing step The impregnated tubular preform is continuously introduced into the pultrusion die and passes through the preheating zone, gelation zone, curing zone and cooling zone in sequence. Under the traction of the traction cutting mechanism, the pultrusion molding and curing are completed to obtain the composite fiber pipe product. S5: Traction Cutting Step The cured pipe is pulled and cut to a set length by a traction cutting mechanism to obtain the finished pipe.

[0012] Furthermore, in step S1: The fiber volume content of the 0-degree axial yarn is 30% to 60%, the fiber volume content of the ±θ degree braided yarn is 20% to 40%, and the fiber volume content of the 90-degree circumferential yarn is 10% to 30%. The braiding angle θ of the ±θ degree braided yarn is adjusted within the range of 15° to 75° according to the mechanical performance requirements of the pipe. The weaving density of the tubular fabric preform is 5 to 20 warp rows / cm, and the coil length of the warp-knitted coil structure is 2 mm to 8 mm.

[0013] Furthermore, in step S3: The vacuum-assisted impregnation device provides a vacuum level of -0.05 MPa to -0.1 MPa; The impregnation temperature is 20℃~60℃; Before step S3, select a core module of the appropriate specification according to the inner diameter of the target pipe, and adjust the core module body to the designed outer diameter through the expansion mechanism; After step S5, the outer diameter of the core mold body is reduced by shrinking the expansion mechanism, thereby achieving automatic demolding of the pipe and the core mold.

[0014] Furthermore, in step S4: The pultrusion speed is 0.1 m / min to 2 m / min; The temperature of the preheating zone is 80℃~120℃, the temperature of the gelation zone is 120℃~180℃, the temperature of the curing zone is 160℃~220℃, and the temperature of the cooling zone is 40℃~80℃. The compression ratio of the pultrusion die is 1.1 to 1.5, so that the impregnated tubular preform is subjected to radial compression when passing through the die; The 0-degree axial yarn, ±θ-degree braided yarn, and 90-degree circumferential yarn are selected from carbon fiber, glass fiber, aramid fiber, basalt fiber, or a mixture thereof; the resin is selected from epoxy resin, vinyl ester resin, or unsaturated polyester resin.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: 1. This application achieves seamless integrated molding of tubular preforms by directly weaving 0° axial yarn, ±θ° woven yarn and 90° circumferential yarn in a tubular space through a multi-axial warp knitting mechanism, eliminating seams and overlapping areas, ensuring continuous fiber without breaks, and significantly improving interlayer bonding strength.

[0016] 2. This application arranges the multi-axial warp knitting mechanism, impregnation mechanism and pultrusion die in series along the same axis, realizing continuous automated production from fiber to finished pipe, overcoming the defects of traditional processes with many steps and low efficiency, and greatly improving production efficiency.

[0017] 3. This application uses at least 3 independently controlled weft laying trolleys, with staggered overlaps between adjacent layers (staggered spacing of 1-5 coils longitudinally), so that the weft yarns of each layer are staggered in the thickness direction. By binding through the warp knitting coils in the thickness direction, the interlayer connection strength and anti-delamination performance are significantly improved, and the wall thickness can be adjusted to a wider range. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the device in this application; Figure 2 This is a front view of the device described in this application; Figure 3 This is a right view of the device described in this application; Figure 4 This is a top view of the device described in this application; Figure 5 for Figure 3 Sectional view along section AA; Figure 6 This is a structural diagram of the tubular coiling mechanism in this application; Figure 7 This is a front view of the tubular coiling mechanism in this application; Figure 8 This is a left view of the tubular coiling mechanism in this application.

[0019] In the diagram: 100. Multi-axial warp knitting mechanism; 110. Circular yarn frame; 111. Spindle; 112. Knitting angle adjustment mechanism; 120. Tubular loop forming mechanism; 121. Composite needle; 122. Guide bar; 123. Sinking plate; 124. Circular needle bed; 125. Boss; 126. Rotating ring; 127. Cam; 128. Spring; 129. Drive motor; 130. Multi-layer weft laying device; 131. Weft laying carriage; 140. Pull-and-wind mechanism; 20 0. Modular core mold system; 210. Core mold body; 211. Core module; 220. Expansion mechanism; 230. Spiral guide channel; 300. Impregnation mechanism; 310. Impregnation tank; 311. Guide plate; 320. Vacuum-assisted impregnation device; 330. Resin circulation temperature control system; 400. Pultrusion mold; 410. Preheating zone; 420. Gel zone; 430. Curing zone; 440. Cooling zone; 450. Insulation section; 500. Traction cutting mechanism. Detailed Implementation

[0020] The present application will be further described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present application.

[0021] Example 1 like Figures 1 to 8 As shown, this application provides an axial composite fiber tube forming device with warp and weft braiding connection, including a multi-axial warp knitting mechanism 100, an impregnation mechanism 300, a pultrusion die 400 and a traction cutting mechanism 500 arranged in series along the same axis, and a modular core mold system 200 passing through the aforementioned mechanisms.

[0022] The multi-axial warp knitting mechanism 100 includes a circular yarn frame 110, a tubular loop-forming mechanism 120, a multi-layer weft-laying device 130, and a pull-and-take-up mechanism 140. The circular yarn frame 110 has 48 sets of spindles 111 evenly arranged along its circumference, respectively supplying 0° axial yarn (carbon fiber, 12K), ±45° knitting yarn (carbon fiber, 12K), and 90° circumferential yarn (carbon fiber, 12K). The tubular loop-forming mechanism 120 has composite needles 121 (crochet needles), guide bars 122 (yarn guide bars), and sinkers 123 arranged along its circumference. The multi-layer weft-laying device 130 includes three independently controlled weft-laying carriages 131, each positioned at a different radial loop position within the circular yarn frame 110, with a staggered spacing of three loop lengths between adjacent weft-laying carriages 131. The middle layer spindle group is equipped with a weaving angle adjustment mechanism 112, which includes an angle adjustment disk, a servo motor and an angle encoder.

[0023] Specifically, the circular yarn frame 110 is the starting point of the entire warp knitting process. Its core function is to orderly draw out three different types of yarns with different directions and functions according to predetermined spatial positions and send them into the downstream loop forming area.

[0024] The inner layer spindle assembly is located at the innermost ring of the annular yarn frame 110, with its spindles arranged parallel to each other along the axial direction. The 0° axial yarn is drawn out from the spindle and inserted parallel to the tubular looping mechanism 120 along the tube's axial direction (i.e., the forming direction). This yarn is distributed straight along the length of the final tube and is the main load-bearing structure for the tube to withstand axial tensile and bending loads. Because the 0° axial yarn hardly buckles in the warp-knitted structure, its tensile modulus and strength can be maximized.

[0025] The middle layer of spindles is located in the middle loop of the annular yarn frame 110. The spindles are arranged at an angle of ±θ° relative to the axial direction, with the θ angle adjustable within the range of 15° to 75°. The ±θ° braided yarns are drawn from the spindles and enter the tubular looping mechanism 120 at a symmetrical inclination angle. During looping, the positive and negative angle yarns intersect to form a mesh-like braided structure. This yarn imparts torsion resistance, shear resistance, and circumferential support to the tube. The adjustability of the θ angle allows the mechanical properties of the tube to be customized according to specific working conditions.

[0026] The outermost spindle assembly is located at the outermost ring of the annular yarn frame 110, with its spindles arranged circumferentially. 90° circumferential yarns are drawn from the spindles and laid circumferentially along the tube, combining with the warp-knitted loop structure in the tubular looping mechanism 120. This yarn is primarily responsible for bearing the circumferential stress of the tube under internal pressure, and is a key reinforcing layer ensuring the tube's resistance to internal pressure.

[0027] The three-layer spindle assembly is arranged concentrically in space, without interfering with each other, enabling independent supply and tension control of the three types of yarn before they enter the looping area.

[0028] The tubular looping mechanism 120 is the core actuator of the entire multi-axial warp knitting mechanism 100. Its function is to bind the yarns introduced from the circular yarn frame 110 in all directions into a whole through the warp knitting loop structure.

[0029] The tubular looping mechanism 120 includes a composite needle 121, a guide bar 122, and a sinker 123 arranged circumferentially. All three are mounted on an annular needle bed 124, forming a complete annular working area. The composite needle 121 reciprocates with the needle bed 124 to hook and feed yarn. A spring 128 is installed at the end of the composite needle 121 to reset it. A boss 125 is provided on the composite needle 121. A rotating ring 126 is provided on one side of the needle bed 124, and is connected to the needle bed 124 by a bearing or sliding connection. The rotating ring 126 rotates inside or outside the needle bed 124. Several cams 127 are arranged circumferentially on the rotating ring 126, with each cam abutting against the boss 125. When the rotating ring 126 rotates, it rotates to the corresponding composite needle 124 to push the composite needle 124. When the cam 127 disengages from the boss 125, the composite needle 124 returns to the starting position under the action of the spring. A drive motor 129 is provided on one side of the rotating ring 126. The output end of the drive motor 129 is connected to the rotating ring 126. Specifically, it can be a gear transmission connection or a friction wheel connection. In this embodiment, a gear transmission connection is used. The drive motor 129 is used to drive the rotating ring 126 to rotate quickly.

[0030] The composite needle 121 is the core actuator in the warp knitting loop process. It adopts a hook needle structure and is arranged circumferentially along the circular needle bed 124.

[0031] The structure of the composite needle 121: The crochet needle has structural components such as a needle shank, a needle hook, and a needle tongue (or needle core). The needle hook is used to hook the yarn, and the needle tongue is used to open and close the needle mouth during the looping process, controlling the looping and unlooping of the yarn.

[0032] The function and movement process of compound needle 121: The compound needle 121 reciprocates during the loop-forming process, coordinating with the oscillation of the guide bar 122 and the pressing action of the sinker 123 to complete a full loop-forming cycle. The loop-forming cycle includes the following stages: The comb 122 is a yarn guiding element, arranged circumferentially along the annular needle bed 124, and configured as a yarn guiding comb.

[0033] Structure of the guide bar 122: The guide bar 122 is equipped with yarn guide needles, each of which guides one or a group of yarns (0° axial yarn, ±θ° braided yarn, or 90° circumferential yarn). The guide bar 122 can make limited oscillating movements around the axis of the circular needle bed 124.

[0034] Yarn positioning and distribution: The guide bar 122 uses guide needles installed on it to accurately position the yarns in each direction to the vicinity of the corresponding composite needle 121 according to the designed structure and arrangement, ensuring that each yarn is accurately supplied to the designated hook needle.

[0035] Yarn-laying motion: When the composite needle 121 rises to its highest point (after the loop is unwound), the guide bar 122 swings laterally, moving the yarn from between the needles to the needle hook position and wrapping it around the needle hook. The displacement of the yarn-laying motion (i.e., the lateral displacement of the guide bar) determines the loop length and weave structure.

[0036] Integration of multi-axial yarns: The comb 122 simultaneously guides the 0° axial yarn (parallel insertion along the axial direction), ±θ° braiding yarn (introduced obliquely), and 90° circumferential yarn (laid out circumferentially), incorporating the yarns in all three directions into the loop structure in one loop formation, achieving true three-dimensional multi-axial integrated molding.

[0037] The yarn padding method for comb 122: The yarn-laying motion of the guide bar 122 differs depending on the direction of the yarn: The padding yarn of the 0° axial yarn: During the loop formation process, it is clamped and bound by the warp knitting loops to maintain axial straightness and prevent buckling. ±θ° Yarn padding: Through the alternating lateral movement of the guide bars, the yarns at positive and negative angles interweave at the needle hooks. 90° circumferential yarn padding: introduced and fixed in the circumferential position of the loop structure in each looping row. The settling plate 123 is a ring-forming auxiliary element, arranged circumferentially along the annular needle bed 124.

[0038] Structure of settling plate 123: Settling plate 123 has a plate nose and plate throat, etc., and is installed between composite needles 121.

[0039] The function of settling plate 123: Yarn pressing function: During the loop forming process, the sinker 123 moves between the needles and presses down the newly formed yarn with the nose of the sinker to prevent it from floating up with the composite needle 121, ensuring that the yarn is stably woven in the loop forming position.

[0040] Holding and pulling: The throat of the settling plate 123 holds the settling arc portion of the coil during the coiling process, and in conjunction with the downward pulling force of the pulling and winding mechanism 140, the coil maintains appropriate tension and stable dimensions during the formation process.

[0041] Assisted loop removal: During the loop removal stage, the sinker 123 assists in supporting the old loop, allowing the old loop to be smoothly removed from the needle head of the composite needle 121 and put on the new yarn, avoiding the loop slippage or deformation.

[0042] Preventing yarn tangling: The sinker plate 123 effectively separates and positions each yarn in the looping area, preventing tangling and interference between yarns in different directions.

[0043] The annular needle bed 124 is an annular track-type base. The composite needles 121, combs 122 and sinkers 123 are all installed on the annular needle bed 124 and arranged in a ring along the circumference.

[0044] The function of the circular needle bed 124: Provides precise mounting positions and motion guides for all coiling components, ensuring the fitting accuracy of each component during high-speed operation; The weaving diameter of the tubular fabric is limited, which determines the basic dimensions of the tubular preform. It provides a stable annular working area, allowing the ring-forming process to proceed uniformly in the 360° circumference.

[0045] In the tubular loop-forming mechanism 120, the hook needle (composite needle 121), the guide bar (bar 122), and the sinker 123 move collaboratively on the circular needle bed 124 to complete the binding of the warp-knitted loop structure. The coordination sequence among the three is as follows: Coil removal phase: Compound needle 121 rises → sinker 123 moves backward → old coil slides to needle bar → comb bar 122 prepares to swing; Yarn padding stage: Compound needle 121 rises to the highest position → Comb bar 122 swings laterally → Guide needles wrap the yarn around the needle hook → Yarn padding is completed; Closing and looping stages: Composite needle 121 begins to descend → needle latch closes → sinker 123 moves forward to press down the yarn → old loop slides up the needle bar; Loop removal and loop formation stage: The composite needle 121 continues to descend to the lowest point → the old loop is removed from the needle tip and put on the new yarn → the new loop is stretched and shaped with the assistance of the sinker 123.

[0046] In the above process, the 0° axial yarn, ±θ° braiding yarn, and 90° circumferential yarn are simultaneously incorporated into the loop structure, and the binding and fixing of the yarns in three directions can be completed in one loop formation. Since the entire loop formation process is carried out continuously in the 360° circumferential direction within the tubular space, the woven tubular fabric is seamless, unbroken, and has continuous fibers.

[0047] The multi-layer weft laying device 130 is a key component for realizing multi-layer weft yarn laying and interlayer mechanical connection, and is set at different radial ring positions of the annular yarn frame 110.

[0048] The multi-layer weft-laying device 130 includes at least three independently controlled weft-laying carriages 131. Each layer of weft-laying carriages 131 is arranged in layers along the thickness direction of the tubular fabric, specifically: The first layer of weft laying carriage is located in the innermost layer, close to the outer surface of the core mold, and lays the innermost layer of weft yarn; The second layer weft laying trolley is located in the middle layer and lays the middle layer weft yarn; The third layer weft laying trolley is located on the outermost layer and lays the outermost weft yarn; A fourth or fifth floor can be added as needed.

[0049] Each layer of weft-laying carriage 131 is independently arranged at different radial loop positions on the annular yarn frame 110, and each layer of weft-laying carriage 131 can rotate independently relative to the axis of the tubular fabric.

[0050] The working principle of the weft-laying trolley 131 is as follows: Reciprocating weft laying: Each layer of weft laying carriage 131 reciprocates around the axis of the tubular fabric upstream of the tubular looping mechanism 120 (i.e., before the yarn enters the looping area). During the rotation, the weft laying carriage 131 carries the weft yarn and lays it circumferentially, spreading the weft yarn in a circumferential state at the corresponding thickness layer position of the preform.

[0051] Independent angle control: The rotation direction and speed of each layer of weft laying carriage 131 can be controlled independently, thereby realizing the independent laying of different layers of weft yarn without interference.

[0052] Continuous laying: The rotation of the weft laying trolley 131 is synchronized with the looping action of the tubular looping mechanism 120. As the tubular fabric moves forward continuously (pulled out by the pull-and-wind mechanism 140), the weft yarn is continuously laid in each looping row.

[0053] The weft-laying carriages 131 of adjacent layers form a staggered overlap, with a staggered spacing of 1 to 5 coil rows. The specific implementation method of the staggered overlap is as follows: Taking a 3-layer weft-laying carriage as an example, after the first layer (innermost layer) lays the weft yarn at a certain loop position, the second layer (middle layer) weft-laying carriage 131 is offset by a certain angle relative to the first layer (corresponding to 1 to 5 loops), laying the weft yarn at different positions in the circumferential direction; the third layer (outermost layer) is then offset by a certain angle relative to the second layer. Thus, the starting points and distribution positions of the weft yarns in each layer are staggered in the circumferential direction.

[0054] The forming process of staggered overlapping is as follows: Before entering the tubular looping mechanism 120, each layer of weft yarn is arranged at different radial positions in the tube wall thickness direction by the independent laying of different layer weft laying carriages 131. In the tubular looping mechanism 120, the coordinated movement of the composite needle 121, the comb 122, and the sinker 123 forms a warp-knitted loop; Warp-knitted loops pass through each layer of weft yarn in the thickness direction, simultaneously binding and fixing the weft yarns of the 1st layer, 2nd layer, 3rd layer, and so on; Because the weft yarns of each layer are staggered by 1 to 5 loops in the circumferential position, the weft yarns of adjacent layers will not overlap at the same loop position, but will form an interlaced arrangement in the thickness direction; Increased wall thickness: By laying multiple layers of weft yarn, the wall thickness of the pipe is no longer limited to the thickness of a single layer of weft yarn, and can be flexibly increased to meet different strength requirements.

[0055] Through-thickness binding: The warp knitting loops simultaneously penetrate each layer of weft yarn, forming a mechanical connection in the thickness direction, so that the layers are not only bonded by resin, but also physically bound together by the loop structure.

[0056] Improved anti-delamination performance: The staggered overlapping structure makes the interface between adjacent layers not a flat resin adhesive surface, but an interlocking mechanical locking structure, which greatly extends the crack propagation path between layers and significantly improves the anti-delamination ability.

[0057] Stress dispersion: The staggered overlapping structure disperses the stress transfer path between layers, avoiding stress concentration on the same cross section.

[0058] The pull-and-wind mechanism 140 is located downstream of the tubular coiling mechanism 120 and is used to continuously pull out the woven tubular fabric along the axial direction.

[0059] The function of the traction and winding mechanism 140: Providing tension: During the looping process, the composite needle 121 rises and tends to lift the fabric upwards. The pull-and-take mechanism 140 applies a continuous downward tension to ensure that the loops are effectively pulled out of the looping area during the looping process, maintaining the continuity and stability of the looping process.

[0060] Controlling braiding density: The pulling speed of the pull-winding mechanism 140 determines the longitudinal density of the coil (i.e., the number of coil rows per centimeter). The faster the pulling speed, the longer the coil is pulled, and the lower the longitudinal density; the slower the pulling speed, the shorter the coil is pulled, and the higher the longitudinal density.

[0061] Tension maintenance: Maintaining constant tension on tubular fabrics during the forming process to prevent deformation caused by fabric slack or excessive stretching.

[0062] Continuous production: The woven tubular fabric is continuously conveyed to the downstream impregnation unit 300 at a constant speed, achieving seamless connection between the weaving process and the subsequent impregnation and pultrusion processes.

[0063] The modular mandrel system 200 includes a mandrel body 210, an expansion mechanism 220, and a spiral guide groove 230. The mandrel body 210 consists of 10 axially connected mandrel modules 211, which are connected by a tapered surface fit. The expansion mechanism 220 is a hydraulic expansion sleeve located inside the mandrel body 210. The spiral guide groove 230 is formed on the outer surface of the mandrel body 210, with a groove depth of 1.5 mm, a pitch of 25 mm, and a semi-circular cross-sectional shape.

[0064] The impregnation mechanism 300 includes a resin impregnation tank 310 and a vacuum-assisted impregnation device 320. The impregnation tank 310 is an open impregnation tank with a guide plate 311 inside. The vacuum-assisted impregnation device 320 is connected to the impregnation tank 310. The impregnation mechanism 300 also includes a resin circulation temperature control system 330.

[0065] The pultrusion die 400 is provided with a preheating zone 410 (temperature 100°C), a gelation zone 420 (temperature 150°C), a curing zone 430 (temperature 190°C) and a cooling zone 440 (temperature 60°C) in sequence along the axial direction, and a heat insulation section 450 is provided between each temperature zone.

[0066] The traction cutting mechanism 500 is located downstream of the pultrusion die 400.

[0067] The process for forming axial composite fiber tubes using the above-mentioned device with warp and weft braiding includes the following steps: S1: Tubular Multi-Axial Warp Knitting Forming Step. Within the tubular space, the 0° axial yarn, ±45° braiding yarn, and 90° circumferential yarn are simultaneously woven using a multi-axial warp knitting mechanism 100 to form a seamless, integrated tubular fabric preform. The 0° axial yarn is inserted parallel to the tube's axis (45% fiber volume content), the ±45° braiding yarn is interwoven at an angle of ±45° relative to the axis (30% fiber volume content), and the 90° circumferential yarn is laid circumferentially along the tube (25% fiber volume content). The yarns in each direction are bound together by a warp-knitted loop structure. Multi-layer weft laying is performed using three independently controlled weft-laying carriages 131. The weft yarn layers of adjacent weft-laying carriages 131 form a staggered overlap with a spacing of three loops, ensuring that the weft yarns of each layer are staggered in the thickness direction. The weft yarns are bound together by warp-knitted loops that penetrate the thickness direction. The weaving density of the tubular fabric preform is 12 loops / cm, and the loop length of the warp-knitted loop structure is 5mm.

[0068] S2: Continuous traction step. The woven tubular fabric preform is continuously pulled along the modular mandrel system 200 to the impregnation mechanism 300 at a speed of 0.5 m / min by the traction and winding mechanism 140.

[0069] S3: Vacuum-assisted impregnation step. Under the negative pressure environment of -0.08MPa provided by the vacuum-assisted impregnation device 320, the tubular fabric preform is introduced into the impregnation tank 310 for epoxy resin impregnation at an impregnation temperature of 40°C. During impregnation, the resin flows uniformly along the axial and circumferential directions along the spiral guide grooves 230 on the outer surface of the modular mandrel system 200, achieving uniform resin distribution in the tube wall thickness direction and circumferential direction.

[0070] S4: Pultrusion Curing Step. The impregnated tubular preform is continuously introduced into the pultrusion die 400, passing sequentially through the preheating zone 410 (100°C), the gelation zone 420 (150°C), the curing zone 430 (190°C), and the cooling zone 440 (60°C). Pultrusion molding and curing are completed under the traction of the traction cutting mechanism 500. The compression ratio of the pultrusion die 400 is 1.3.

[0071] S5: Traction Cutting Step. The cured pipe is pulled and cut to a set length by the traction cutting mechanism 500 to obtain the finished pipe. Then, the outer diameter of the mandrel body 210 is reduced by shrinking the hydraulic expansion sleeve, realizing automatic demolding of the pipe and the mandrel.

[0072] The composite fiber pipe prepared in this application has a fiber volume content of 62% and an interlayer shear strength that is 32% higher than that of pipes prepared by the traditional planar braiding-winding process.

[0073] Example 2 The difference between this embodiment and Embodiment 1 is that the annular yarn frame 110 has 32 sets of spindles 111 arranged circumferentially. The 0° axial yarn is made of glass fiber (24K), the ±θ° woven yarn is made of glass fiber (24K), the θ angle is 60°, and the 90° circumferential yarn is made of glass fiber (24K). The fiber volume content is as follows: 50% for the 0° axial yarn, 25% for the ±60° woven yarn, and 25% for the 90° circumferential yarn.

[0074] The multi-layer weft laying device 130 includes 5 independently controlled weft laying trolleys 131, with a staggered spacing of 2 coils longitudinally.

[0075] The expansion mechanism 220 of the modular core mold system 200 is a mechanical expansion mechanism, which realizes the radial expansion and contraction of the core module 211 through threaded transmission. The spiral guide groove 230 has a rectangular cross-sectional shape, a groove depth of 2mm, and a pitch of 30mm.

[0076] The impregnation temperature of the impregnation mechanism 300 is 50°C, and the vacuum degree is -0.09MPa.

[0077] The preheating zone 410 of the pultrusion die 400 has a temperature of 90°C, the gelation zone 420 has a temperature of 140°C, the curing zone 430 has a temperature of 180°C, and the cooling zone 440 has a temperature of 50°C. The pultrusion speed is 0.8 m / min, and the compression ratio of the pultrusion die 400 is 1.2.

[0078] The glass fiber composite pipe produced in this embodiment is suitable for chemical pipelines and electrical insulation pipes.

[0079] Example 3 The difference between this embodiment and Embodiment 1 is that the annular yarn frame 110 has 56 sets of spindles 111 arranged circumferentially. The 0° axial yarn is made of aramid fiber, the ±θ° woven yarn is made of aramid fiber, the θ angle is 30°, and the 90° circumferential yarn is made of aramid fiber. The fiber volume content is as follows: 35% for the 0° axial yarn, 35% for the ±30° woven yarn, and 30% for the 90° circumferential yarn.

[0080] The multi-layer weft laying device 130 includes four independently controlled weft laying carriages 131, with a staggered spacing of four coil longitudinal rows.

[0081] The impregnation temperature of the impregnation mechanism 300 is 30°C, and the vacuum degree is -0.07MPa.

[0082] The preheating zone 410 of the pultrusion die 400 has a temperature of 110°C, the gelation zone 420 has a temperature of 160°C, the curing zone 430 has a temperature of 200°C, and the cooling zone 440 has a temperature of 70°C. The pultrusion speed is 0.3 m / min, and the compression ratio of the pultrusion die 400 is 1.4.

[0083] The aramid fiber composite tube prepared in this embodiment is suitable for aerospace structural components with high requirements for impact toughness and anti-delamination performance.

[0084] Example 4 The difference between this embodiment and Embodiment 1 is that the 0° axial yarn uses a hybrid combination of carbon fiber and glass fiber (12K carbon fiber and 24K glass fiber are mixed in a 1:1 volume ratio), the ±45° braided yarn uses carbon fiber (12K), and the 90° circumferential yarn uses basalt fiber. The resin used is vinyl ester resin.

[0085] The multi-layer weft laying device 130 includes 6 independently controlled weft laying trolleys 131 with a staggered spacing of 1.5 coils.

[0086] The spiral guide groove 230 has a groove depth of 1mm, a pitch of 20mm, and a trapezoidal cross-sectional shape.

[0087] The pultrusion speed is 0.6 m / min, and the compression ratio of the pultrusion die 400 is 1.35.

[0088] This embodiment achieves optimized matching of the mechanical properties of the pipe through hybrid fiber combination, taking into account both the high strength of carbon fiber and the cost-effectiveness advantages of glass fiber / basalt fiber.

[0089] Example 5 The difference between this embodiment and Embodiment 1 is that the θ angle of the ±θ° braided yarn is dynamically adjusted within the range of 15° to 75° according to the mechanical performance requirements of the pipe. When the pipe requires higher axial tensile strength, the θ angle is reduced to 20°; when the pipe requires higher circumferential support force and torsional strength, the θ angle is increased to 65°. The braiding angle adjustment mechanism 112 detects the actual braiding angle in real time through an angle encoder and performs closed-loop adjustment by driving the angle adjustment disk through a servo motor, so that the deviation between the actual braiding angle and the set value is controlled within ±1°.

[0090] The weaving density of the tubular fabric preform is 8 warp rows / cm, and the coil length of the warp-knitted coil structure is 6mm.

[0091] The embodiments of this application realize the on-demand designability of the mechanical properties of the pipe, and the fiber angle can be flexibly adjusted according to different working conditions.

[0092] Industrial applicability The forming device and forming process for axial composite fiber tubes with warp and weft braiding provided in this application enable continuous automated production from fiber to finished tube. It has high production efficiency, stable product quality, and wide applicability, and has good industrial practical value and application prospects.

[0093] Of course, the above embodiments are not intended to limit this application, and this application is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this application should also fall within the protection scope of this application.

Claims

1. A device for forming axial composite fiber tubes with warp and weft braided connections, characterized in that: include: A multi-axial warp knitting mechanism (100) is used to directly knit preforms within a tubular space; Impregnation mechanism (300) for impregnating woven preforms with resin; Pultrusion die (400) is used to form the impregnated woven preform; A modular core mold system (200) extends through the multi-axial warp knitting mechanism (100), the impregnation mechanism (300), and the pultrusion die (400). Traction cutting mechanism (500) for traction and cutting of pipes.

2. The axial composite fiber tube forming device with warp and weft braiding connection according to claim 1, characterized in that: The multi-axial warp knitting mechanism (100) includes: A circular yarn frame (110) is used to supply multi-axial braided yarn; The tubular coiling mechanism (120) includes composite needles (121), combs (122) and settling plates (123) arranged in a circumferential direction. The multi-layer weft laying device (130) includes at least three independently controlled weft laying trolleys (131), each layer of weft laying trolleys (131) is arranged in layers along the thickness direction of the tubular fabric and can rotate relative to each other around the axis of the tubular fabric. The pull-and-wind mechanism (140) is used to continuously pull out the woven tubular fabric preform along the axial direction.

3. The axial composite fiber tube forming device with warp and weft braided connection according to claim 2, characterized in that: The annular yarn frame (110) is provided with a knitting angle adjustment mechanism, including: an angle adjustment disk, which is installed on the yarn carrier of the middle layer yarn spindle group; a servo motor, which drives the angle adjustment disk to rotate to change the yarn lead-out angle; and an angle encoder, which is used to detect and feedback the actual knitting angle of the ±θ degree knitting yarn in real time, so that the deviation between the actual knitting angle and the set value is controlled within ±1 degree.

4. The axial composite fiber tube forming device with warp and weft braiding connection according to claim 1, characterized in that: The modular core mold system (200) includes: The core mold body (210) is composed of multiple core modules spliced ​​along the axial direction, and the core modules are connected by a conical surface fit. The spiral guide groove (230) is formed on the outer surface of the core mold body (210). It is a spiral groove that extends continuously along the outer surface of the core mold. The groove depth is 0.5mm to 3mm and the pitch is 10mm to 50mm. It is used to guide the resin to flow uniformly in the axial and circumferential directions during the impregnation process.

5. The axial composite fiber tube forming device with warp and weft braided connection according to claim 1, characterized in that: The impregnation mechanism (300) includes an impregnation tank (310) and a resin circulation temperature control system (330). The impregnation tank (310) is an open impregnation tank with a guide plate (311) inside to guide the resin flow. The resin circulation temperature control system (330) is used to control the resin temperature in the impregnation tank (310).

6. The axial composite fiber tube forming device with warp and weft braided connection according to claim 1, characterized in that: The pultrusion die (400) includes a preheating zone (410), a gelation zone (420), a curing zone (430), and a cooling zone (440). The temperature of the preheating zone (410) is 80℃~120℃, the temperature of the gelation zone (420) is 120℃~180℃, the temperature of the curing zone (430) is 160℃~220℃, and the temperature of the cooling zone (440) is 40℃~80℃. A heat insulation section (450) is provided between each temperature zone.

7. A forming process for axial composite fiber tubing with warp and weft braided connections, characterized in that: The axial composite fiber tube forming apparatus using the warp and weft braided connection as described in any one of claims 1 to 6 includes the following steps: S1: Tubular Multiaxial Warp Knitting Forming Steps Within the tubular space, 0-degree axial yarn, ±θ-degree braided yarn, and 90-degree circumferential yarn are simultaneously braided by a multi-axial warp knitting mechanism (100) to form a seamless integrated tubular fabric preform. Among them, the 0-degree axial yarn is inserted parallel to the tube axis, the ±θ-degree braided yarn is interwoven at a ±θ-degree angle relative to the axis, and the 90-degree circumferential yarn is laid circumferentially along the tube. The yarns in each direction are bound together as a whole by a warp knitting loop structure. At least three layers of independently controlled weft laying carriages (131) are used for multi-layer weft laying. The weft yarn layers of adjacent weft laying carriages (131) are staggered and overlapped. The staggered spacing is 1 to 5 loops in the longitudinal direction, so that the weft yarns of each layer are staggered in the thickness direction and bound by the warp knitting loops through the thickness direction. S2: Continuous traction steps The woven tubular fabric preform is continuously pulled along the modular core mold system (200) to the impregnation mechanism (300) by the traction and winding mechanism (140). S3: Vacuum-assisted impregnation step Under the negative pressure environment provided by the vacuum-assisted impregnation device (320), the tubular fabric preform is introduced into the impregnation tank (310) for resin impregnation; during the impregnation process, the resin flows uniformly along the axial and circumferential directions along the spiral guide groove (230) on the outer surface of the modular core mold system (200), so as to achieve uniform distribution of resin in the tube wall thickness direction and circumferential direction. S4: Pultrusion curing step The impregnated tubular preform is continuously introduced into the pultrusion mold (400), and passes through the preheating zone (410), gel zone (420), curing zone (430) and cooling zone (440) in sequence. Under the traction of the traction cutting mechanism (500), the pultrusion molding and curing are completed to obtain the composite fiber pipe product. S5: Traction Cutting Step The cured pipe is pulled and cut to a set length by the traction cutting mechanism (500) to obtain the finished pipe.

8. The forming process for axial composite fiber tubing with warp and weft braiding according to claim 7, characterized in that: In step S1, the fiber volume content of the 0-degree axial yarn is 30%–60%, the fiber volume content of the ±θ-degree braided yarn is 20%–40%, and the fiber volume content of the 90-degree circumferential yarn is 10%–30%. The braiding angle θ of the ±θ-degree braided yarn is adjusted within the range of 15°–75° according to the mechanical performance requirements of the tube. The braiding density of the tubular fabric preform is 5–20 warp rows / cm, and the loop length of the warp-knitted loop structure is 2mm–8mm.

9. The forming process for axial composite fiber tubing with warp and weft braiding according to claim 7, characterized in that: In step S3, the vacuum-assisted impregnation device (320) provides a vacuum of -0.05MPa to -0.1MPa; the impregnation temperature is 20℃ to 60℃; before step S3, a core module of the appropriate specification is selected according to the inner diameter of the target pipe, and the core mold body (210) is adjusted to the designed outer diameter by the expansion mechanism; after step S5, the outer diameter of the core mold body (210) is reduced by shrinking the expansion mechanism, so as to realize the automatic demolding of the pipe and the core mold.

10. The forming process for axial composite fiber tubing with warp and weft braiding according to claim 7, characterized in that: In step S4, the pultrusion speed is 0.1 m / min to 2 m / min; the temperature of the preheating zone (410) is 80℃ to 120℃, the temperature of the gelation zone (420) is 120℃ to 180℃, the temperature of the curing zone (430) is 160℃ to 220℃, and the temperature of the cooling zone (440) is 40℃ to 80℃; the compression ratio of the pultrusion die (400) is 1.1 to 1.5, so that the impregnated tubular preform is subjected to radial compression when passing through the die; the 0-degree axial yarn, ±θ-degree braided yarn and 90-degree circumferential yarn are selected from carbon fiber, glass fiber, aramid fiber, basalt fiber or a mixture thereof; the resin is selected from epoxy resin, vinyl ester resin or unsaturated polyester resin.

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