Light wear-resistant composite material needle cylinder for composite needle circular weft knitting machine and preparation method of light wear-resistant composite material needle cylinder

Abstract

The invention belongs to the technical field of textile machinery, and discloses a light wear-resistant composite material needle cylinder for a composite needle circular weft knitting machine and a preparation method of the light wear-resistant composite material needle cylinder, the light wear-resistant composite material needle cylinder comprises a base body and wear-resistant parts, the base body is a cylindrical carbon fiber preform, and the wear-resistant parts are a plurality of tubular hard alloy bushings; the wear-resistant part is embedded into the base body through a mounting hole reserved in the base body, and the outer surface of the wear-resistant part is combined with the base body in a mechanical interlocking mode. The preparation method comprises the following steps: after weaving a cylindrical carbon fiber preform, putting the cylindrical carbon fiber preform into a split steel mold, mounting a plurality of circular-tube-shaped hard alloy bushings with mechanical interlocking structures into preformed hole sites, closing the mold and locking; and heating the cylindrical carbon fiber preform to make the resin infiltrate the cylindrical carbon fiber preform, and then carrying out heating, heat preservation curing, demolding and precision processing to obtain the light wear-resistant composite material needle cylinder for the composite needle circular weft knitting machine. According to the invention, light weight is realized, and high rigidity, high wear resistance, good thermal conductivity and low thermal expansion coefficient are realized.

Description

Technical Field

[0001] This invention belongs to the field of textile machinery technology and relates to a lightweight wear-resistant composite material syringe for a composite needle circular weft knitting machine and its preparation method. Background Technology

[0002] With the increasing market demand for high-specification knitted fabrics, weft-knitted circular knitting machines are continuously developing towards higher gauge and higher speeds, which places higher demands on the overall performance of the core component, the needle cylinder. Traditional needle cylinders mostly use a single metal material, which has inherent defects in terms of lightweighting and wear resistance: on the one hand, high-density materials result in heavy needle cylinders and high rotational inertia, causing not only slow start-stop and speed adjustment responses and significantly increased energy consumption, but also bringing the risk of braking impact; on the other hand, a single material structure cannot simultaneously meet the extreme wear resistance requirements under high-speed conditions and the overall lightweight requirements, often at the expense of one. For example, high wear-resistant alloy steel is too heavy, while lightweight materials generally lack sufficient wear resistance. In addition, traditional needle cylinders are also prone to thermal deformation due to frictional heat during high-speed, long-term operation, further affecting accuracy and lifespan.

[0003] In the existing technology, relevant patents provide a variety of technical solutions, but all of them have certain limitations:

[0004] Patent CN201447554U discloses a needle bed for a warp knitting machine. This needle bed uses a carbon fiber composite matrix for lightweighting and employs a dovetail / T-slot mechanical locking structure combined with adhesive to fix the needle holder. It also uses segmented V / W-type positioning surfaces to reduce manufacturing difficulty. However, because it relies on the adhesive to bear the main shear force, fretting wear easily occurs at the segmented connections during high-speed reciprocating motion, leading to loosening or misalignment. Furthermore, the mechanical locking structure cannot effectively restrict the freedom of the needle holder along its length, resulting in insufficient connection reliability and dynamic stability. This technology is limited to lightweighting and connection improvements for warp knitting machine needle beds and cannot address the extreme performance requirements of rotating cylinders on weft knitting circular knitting machines under high gauge and high-speed conditions.

[0005] Patent CN223202027U discloses a needle bed assembly. This patent uses a hollow carbon fiber composite crossbar body, cured with epoxy resin, to replace traditional aluminum-magnesium alloy. This effectively reduces weight and utilizes the low coefficient of thermal expansion of carbon fiber to solve the problems of needle misalignment and thread breakage caused by thermal deformation during high-speed operation. However, this method has limitations: the hollow structure of the carbon fiber composite may weaken the overall torsional stiffness to some extent, and the epoxy resin may age under long-term high-speed operation, affecting the long-term reliability of the connection.

[0006] Patent CN219045010U discloses a wear-resistant double-sided circular knitting machine cylinder, with wear-resistant layers on both the outer and inner layers of the cylinder body. The bottom is connected to the base via a positioning rod and includes a rotating mechanism. However, the double-layer wear-resistant structure increases manufacturing costs and cylinder thickness, and places higher demands on the subsequent precision milling of the needle grooves. Furthermore, if the thermal expansion coefficients of the different material layers are not properly matched, thermal stress may affect the overall shape and position accuracy after high-speed operation and heat generation.

[0007] Patent application CN118814044A discloses a wear-resistant tungsten carbide material and its manufacturing process. This process modifies the alloy composition of existing tungsten carbide materials, enhancing the stability of the internal molecules and causing changes in grain structure during sintering, resulting in grain refinement. This improves the wear resistance and mechanical properties of the tungsten carbide material, leading to high overall performance. However, due to the presence of rare metals such as tantalum and yttrium, the raw material cost is high, making large-scale application economically unfeasible. Therefore, it is not suitable for cost-sensitive general applications.

[0008] Patent CN118086770B discloses a low-alloy high-wear-resistant steel and its preparation method. This method optimizes the alloy composition of the low-alloy high-wear-resistant steel to achieve a balance between wear resistance and toughness. However, while the low-alloy design effectively reduces costs, its wear resistance is inevitably lower than that of high-cobalt, high-carbon high-alloy steel. This means that the service life of syringes made from this material may become a bottleneck under extremely abrasive conditions such as weaving high-tensile yarns, glass fibers, or carbon fibers. Furthermore, the material's advantage lies only in achieving excellent cost-effectiveness under normal to moderate wear conditions.

[0009] Therefore, there is an urgent need in this field for a lightweight and wear-resistant composite material syringe for composite needle circular knitting machines and its preparation method, which can fundamentally break through the technical bottleneck that makes it difficult to achieve both lightweight and high wear resistance. Summary of the Invention

[0010] The purpose of this invention is to solve the problems existing in the prior art and to provide a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine and its preparation method.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A lightweight wear-resistant composite material syringe for a composite needle circular knitting machine includes a matrix and wear-resistant parts. The matrix is ​​a cylindrical carbon fiber preform. Since the wear-resistant parts directly bear friction, the wear-resistant parts of this invention are multiple cylindrical hard alloy bushings. The hard alloy has an HRC (Rockwell hardness) ≥68, and its hardness and wear resistance are significantly higher than those of traditional bearing steel for syringes, which greatly extends the needle groove life.

[0013] The substrate has pre-drilled mounting holes, and the wear-resistant parts are embedded into the substrate axially through the pre-drilled mounting holes. The RTM (Resin Transfer Molding) process is used to achieve integrated composite molding.

[0014] The outer surface of the wear-resistant part is mechanically interlocked with the substrate. For example, the outer surface of the wear-resistant part is provided with grooves, textures, or microporous structures. During the RTM (Resin Transfer Molding) process, the flowing resin fills and cures in these structures to form an anchoring structure, thereby achieving mechanical interlocking between the wear-resistant part and the substrate. In addition, this mechanically interlocked interface design can also ensure that complex mechanical stresses (such as the lateral impact force of knitting needles) can be reliably transmitted between two materials with significantly different physical properties, avoiding the risk of delamination that may occur with simple chemical bonding and ensuring the long-term reliability of the composite structure. The inner surface of the wear-resistant part forms a needle groove working surface for the movement of knitting needles.

[0015] As a preferred technical solution:

[0016] As described above, the lightweight wear-resistant composite material syringe for a composite needle circular knitting machine is made of cylindrical carbon fiber preforms obtained through three-dimensional weaving. During the weaving process, precise mounting holes are reserved for the wear-resistant parts, which ensures the accuracy of the hole positions (such as outer diameter tolerance ±0.002mm), and also avoids errors caused by post-processing.

[0017] The cylindrical carbon fiber preform has a fiber volume fraction of no less than 60% in both the circumferential and axial directions to ensure that the syringe has extremely high circumferential stiffness and axial bending stiffness under high-speed operation, resisting centrifugal force and yarn tension during high-speed operation, maintaining geometric stability, and undertaking the main heat conduction task.

[0018] As described above, the lightweight wear-resistant composite material syringe for a composite needle circular knitting machine has 4,000 to 6,500 tubular cemented carbide bushings, preferably 4,800 to 6,100, which are evenly distributed. Since the number, position, and spacing of the tubular cemented carbide bushings are determined by the syringe's serial number (e.g., E42, E44) (for example, an E44 syringe requires approximately 5,530 tubular cemented carbide bushings based on calculations (serial number 44 × syringe diameter 40 × 3.1416 ≈ 5529.6 needles), each corresponding to one needle groove), their distribution must be uniform and circumferentially symmetrical to ensure dynamic balance and needle groove accuracy. Furthermore, the tubular cemented carbide bushings, as hard points embedded in the matrix, affect the syringe's circumferential stiffness and impact resistance; uniform distribution avoids stress concentration and ensures uniform load transfer.

[0019] As described above, in a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine, the area where the wear-resistant parts are located accounts for 75-90% of the circumference of the syringe, meaning that a continuous area of ​​10-25% of the circumference of the syringe does not have wear-resistant parts.

[0020] The lightweight wear-resistant composite material syringe for a composite needle circular knitting machine, as described above, uses a tungsten-cobalt (WC-Co) alloy or free-cutting steel as the cemented carbide.

[0021] The cobalt content in tungsten-cobalt (WC-Co) alloys is 6-16 wt%, preferably 6-8 wt%.

[0022] The chemical composition of free-cutting steel, by mass percentage, includes: carbon (C) ≤ 0.5%, manganese (Mn) 1.00~1.30%, chromium (Cr) ≤ 0.2%, nickel (Ni) ≤ 0.2%, copper (Cu) ≤ 0.3%, sulfur (S) 0.04~0.09%, phosphorus (P) ≤ 0.04%, with the balance being Fe and unavoidable impurities.

[0023] As described above, this invention relates to a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine. Based on the principle of material thermal stress control, through proactive design and selection, the CTE (Coefficient of Thermal Expansion) of the wear-resistant component and the carbon fiber matrix is ​​made highly similar in value. Furthermore, to prevent localized thermal stress concentration, the distribution density and location of the wear-resistant component must be coordinated with the thermal expansion coefficient of the matrix. Therefore, the absolute value of the difference between the circumferential thermal expansion coefficients of the wear-resistant component and the matrix is ​​set to be no greater than 3.0 × 10⁻⁶. -6 / ℃, so that the thermal expansion and contraction of the two when the temperature changes tend to be synchronized, thereby fundamentally eliminating the destructive thermal stress at the interface caused by CTE mismatch, and avoiding the cracking of the bonding interface or the overall warping caused by thermal stress. This maintains the original machining accuracy of the pin groove for a long time and helps the overall thermal stability.

[0024] The present invention also provides a method for preparing a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine as described in any of the preceding claims, comprising the following steps:

[0025] (1) A cylindrical carbon fiber preform is woven using three-dimensional weaving technology to form a non-layered overall skeleton, which fundamentally solves the risk of delamination and also gives the matrix extremely high circumferential stiffness and tear resistance. In addition, during the weaving process, mounting holes are reserved on the cylindrical carbon fiber preform for wear-resistant parts. Since the carbon fiber composite (CFRP) matrix has the characteristics of low specific gravity, high specific strength and high specific modulus, after specific layup design, the coefficient of thermal expansion (CTE) of CFRP in its fiber direction can be adjusted to a very low level, even close to zero. This also ensures the overall lightweight of the syringe, facilitates energy saving during start-up and shutdown, provides extremely high structural stability, and ensures small deformation under high-speed rotation.

[0026] (2) A mechanical interlocking structure, such as grooves, textures or micropores, is processed on the outer surface of a cylindrical hard alloy bushing using a laser.

[0027] (3) First, place the cylindrical carbon fiber preform woven in step (1) into the split steel mold, and then accurately install the multiple cylindrical hard alloy bushings with mechanical interlocking structure pre-processed in step (2) into the reserved holes of the cylindrical carbon fiber preform, so that the end faces of all the cylindrical hard alloy bushings are flush with the end faces of the cylindrical carbon fiber preform. Then close the mold and lock it. The accuracy of the mold cavity determines the final external dimensions of the syringe. In mechanical manufacturing and engineering drawing, "end face" specifically refers to the two outermost planes of a cylindrical or cylindrical workpiece along its axial direction.

[0028] (4) Heat the mold to 100~120℃, and then inject the high-temperature resistant epoxy resin filled with thermally conductive filler into the mold cavity under an injection pressure of 0.5~0.8MPa. Keep it warm and pressurized for 30~60min so that the resin can fully impregnate the cylindrical carbon fiber preform and wrap the outer surface of the cylindrical hard alloy bushing. The glass transition temperature (Tg) of the high-temperature resistant epoxy resin is not lower than 150℃, the thermal conductivity of the high-temperature resistant epoxy resin filled with thermally conductive filler is not lower than 0.8W / (m·K), the filling ratio of the thermally conductive filler is 55~75wt%, and its own thermal conductivity is not lower than 10W / (m·K). When keeping it warm and pressurized, the resin will not only fill the micro-groove of the bushing, but it will actually cover and wrap the entire preform and the outer cylindrical surface and two end faces of all bushings. Therefore, it is necessary to design the mold to protect the inner hole of the bushing (the future working surface of the needle groove) from being completely blocked by resin. For example, a core can be used: during mold assembly, a high-precision metal core is inserted into the inner hole of each wear-resistant bushing. The outer diameter of these cores is matched with the inner hole of the bushing with a small clearance. After demolding, the core is removed, and the inner hole of the bushing will remain clean and resin-free, preparing for subsequent precision milling.

[0029] (5) Heat the mold to 160~180℃ and keep it under heat and pressure for 2~3 hours to allow the resin to fully cure. Its high thermal conductivity resin matrix and carbon fiber three-dimensional preform together form a three-dimensional thermally conductive network (that is, a continuous, three-dimensional fiber thermally conductive skeleton is established in space. Therefore, after curing, the structure formed by the two can be called a three-dimensional thermally conductive network), which can quickly diffuse the heat generated in the needle groove friction area to the entire syringe, and achieve efficient heat dissipation through contact with the external cooling system, fundamentally suppressing the thermal deformation caused by local overheating.

[0030] (6) After demolding, a composite syringe blank is obtained. The composite syringe blank is then precision machined to obtain a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine.

[0031] The interlocking mechanism of this invention involves first machining a mechanical interlocking structure on the outer surface of a cylindrical hard alloy bushing. Then, during the RTM process, resin is injected into a mold to fill these interlocking structures. After curing, the resin forms an "anchoring" effect within the grooves, mechanically locking the wear-resistant component to the substrate. This ensures that the interface will not delaminate or loosen under stress (such as needle impact) and thermal changes; in other words, these groove structures are filled with resin integrated with the substrate. Therefore, the mechanical interlocking is bidirectional; the wear-resistant component is embedded in the substrate resin through its surface structure, forming an interlock, rather than relying solely on chemical bonding. This improves the bonding strength and long-term reliability.

[0032] As a preferred technical solution:

[0033] The method for preparing a lightweight, wear-resistant composite needle cylinder for a composite needle circular knitting machine, as described above, uses aluminum nitride (AlN) and / or boron nitride (BN) surface-treated with a silane coupling agent as the thermally conductive filler, preferably boron nitride, because it not only has high thermal conductivity (sheet-like BN can reach 30~60) but also... It also possesses excellent electrical insulation, low dielectric constant and loss, and a graphite-like layered lubricating structure, which helps improve the processing fluidity of the composite material. When using a compound system (such as AlN and BN), the advantages of different fillers can be taken into account, and the filler packing density can be optimized, thereby constructing a thermally conductive network more efficiently. In addition, surface treatment with silane coupling agent can significantly improve the interfacial compatibility between inorganic fillers and organic resin matrix, enhance interfacial bonding, not only benefiting thermal conductivity but also reducing interfacial defects, improving the mechanical properties and long-term reliability of the composite material. The filling ratio of thermally conductive filler is preferably 60~70wt%. Within this range, it can ensure that the filler particles form a continuous thermally conductive path with sufficient contact, thereby significantly improving the thermal conductivity of the system, while ensuring that the resin system still has sufficient fluidity to complete the complete impregnation of the carbon fiber preform and avoiding difficulties in glue injection due to excessive viscosity.

[0034] Meanwhile, the particle size of the filler adopts a bimodal or wide distribution design. Large-diameter filler (i.e., D50 of 20~45μm) is used to form the main skeleton of the heat conduction network, while small-diameter filler (i.e., D50 of 1~5μm) is used to fill the gaps between large-diameter fillers, increase the packing density, and reduce phonon scattering. This particle size configuration can achieve relatively low viscosity and higher thermal conductivity at high filler content.

[0035] The preparation method of a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine, as described above, involves precision machining of the composite syringe blank as follows: first, the two end faces are precision machined with the outer circle of the substrate as a reference; then, the inner hole of the circular tubular carbide bushing is precision milled using a PCD tool to form a high-precision needle groove.

[0036] Beneficial effects:

[0037] (1) The present invention uses a cylindrical carbon fiber preform woven from carbon fiber material as the matrix, which achieves significant lightweighting and high structural stiffness, and its adjustable coefficient of thermal expansion ensures excellent thermal stability.

[0038] (2) The present invention adopts a composite structure design with a cylindrical carbon fiber preform as the matrix and multiple cylindrical hard alloy bushings as wear-resistant parts. Through the complementary advantages of materials rather than simple stacking, it systematically solves the technical problem that a single material cannot simultaneously achieve lightweight, high rigidity, high wear resistance, good thermal conductivity and low thermal expansion coefficient. It is especially suitable for high-gauge, high-speed weft knitting circular knitting machines.

[0039] (3) The present invention achieves a high-strength and high-stability bond between dissimilar materials by using the manufacturing process of "pre-embedded fitting + RTM integrated molding" and combining it with the mechanical interlocking interface, effectively solving the problem of interface failure caused by thermal expansion differences.

[0040] (4) The present invention uses high-performance wear-resistant alloy only in the most critical friction parts, which effectively controls the overall material cost. At the same time, it reduces downtime maintenance time due to its long life characteristics, showing good comprehensive economic benefits.

[0041] (5) The present invention uses a high thermal conductivity resin (thermal conductivity ≥0.8W / (m·K)) and directly fills the interface to form a continuous thermal conduction path, which can quickly diffuse the frictional heat and reduce the temperature rise by more than 57%.

[0042] (6) The pre-embedded fitting of the present invention ensures that the wear-resistant parts and the substrate are positioned at one time. After RTM curing, the overall accuracy is high, the dynamic balance level reaches G2.5, and the integrated structure has a long service life. In addition, when it is a split design, it is easier to replace in a modular way, and the maintenance cost is reduced by more than 70%. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the substrate on which the wear-resistant parts are installed in Embodiment 4 of the present invention;

[0044] Figure 2 This is a schematic diagram of the wear-resistant component being installed on the substrate in Embodiment 4 of the present invention;

[0045] Figure 3 This is a schematic diagram of an embodiment 4 of the present invention, which includes an interlocking structure and a pin groove;

[0046] Figure 4 This is a schematic diagram of the overall structure of the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine in Embodiment 3 of the present invention;

[0047] In the figure, 1-substrate, 2-wear-resistant part, 3-V-groove, 4-pin groove, 5-upper ring, 6-lower ring. Detailed Implementation

[0048] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0049] To ensure that the performance of the substances used in each embodiment is fully disclosed, the manufacturers and brands of the substances are specified. Other products from manufacturers and brands that conform to the limitations of this invention are also feasible.

[0050] The testing methods for the relevant performance indicators in the following embodiments are as follows:

[0051] Fiber volume fraction: The cross-section of the sample is analyzed by microscopic analysis (such as metallographic microscope, micro-CT) to identify and count the fibers in the axial and circumferential directions, and calculate their proportion in the region.

[0052] Thermal conductivity: The thermal conductivity of the sample was determined using a steady-state thermal conductivity meter (model: DRL-III) according to GB / T 10297-2015 "Determination of thermal conductivity of non-metallic solid materials by hot wire method". During the test, after the system reaches steady state, three sets of data need to be collected continuously, and the relative deviation of the three measurement results should not exceed 3%. The arithmetic mean was then taken as the final result unit W / (m·K). The test parameters were as follows: the sample size WE was a flat sample of 300mm×300mm×actual thickness made of the same material as the syringe base; the average test temperature was 50℃; the temperature difference between the hot and cold plates was 20℃ (hot plate 60℃, cold plate 40℃); the contact pressure was 2.5kPa; the test environment temperature was 23℃; and the relative humidity was 50%.

[0053] HRC of cemented carbide: The hardness of the samples was tested using a Rockwell hardness tester in accordance with GB / T 230.1-2018 "Metallic materials Rockwell hardness test - Part 1: Test method". The results were read directly on the Rockwell hardness tester based on the depth difference. The initial test force was 98.07 N, the main test force was 1471 N, the indenter type was a diamond conical indenter (apex angle 120°), and the ambient temperature was 20℃.

[0054] Needle groove wear depth: Select a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine to be tested for needle groove wear depth. Then, use the same hard alloy bushing as the syringe and embed it into a small carbon fiber preform sample. After curing using the same RTM process as the composite needle circular knitting machine lightweight wear-resistant composite material syringe, process it into a standard test block. Then, refer to GB / T 12444-2006 "Metallic Materials Wear Test Methods - Test Rings - Test Blocks - Sliding Wear Test" standard and use a ring-block wear tester (model: M-2000) to test the wear depth of the sample. This is done by measuring the wear mark width at the middle and both ends (1 mm from the edge), taking the arithmetic mean of three measurements, and calculating the volumetric wear (in mm) based on this. 3 The wear resistance of the sample is denoted as 12.32 mm (width) × 19.05 mm (length). The ambient temperature is 25℃. The test ring is GCr15 steel with a hardness of 62HRC. The load is 130N. The rotation speed is 200r / min. The total number of revolutions is 5000r. The lubrication condition is dry friction.

[0055] Example 1

[0056] A method for preparing a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine, applicable to a high-speed single-sided weft knitting circular knitting machine with a syringe diameter of 38 inches and a machine size of E44, the specific steps are as follows:

[0057] (1) Preparation of raw materials;

[0058] Carbon fiber: 24K carbon fiber, manufactured by Weihai Guangwei Composite Materials Co., Ltd., grade CCF700G;

[0059] Hard alloy: Tungsten-cobalt alloy, HRC 68, cobalt content in the tungsten-cobalt alloy is 8wt%;

[0060] Filler: Aluminum nitride, with a large particle size D50 of 25 μm and a small particle size D50 of 3 μm;

[0061] Silane coupling agent: KH-550;

[0062] High-temperature resistant epoxy resin: Manufacturer is D.E. (China) Investment Co., Ltd., brand name is HP-4710, glass transition temperature is 253℃;

[0063] (2) The carbon fiber is woven into a cylindrical carbon fiber preform with a thickness of 10 mm using three-dimensional weaving technology. During the weaving process, 5530 mounting holes are reserved on the cylindrical carbon fiber preform for wear-resistant parts.

[0064] The woven cylindrical carbon fiber preform has a fiber volume fraction of 65% in the circumferential direction and 65% in the axial direction.

[0065] (3) First, 5530 cylindrical cemented carbide bushings with an outer diameter of Φ4mm and an inner diameter of Φ2.2mm (with a final milling allowance) are precision ground. Then, grooves are machined on the outer surface of each cylindrical cemented carbide bushing using a laser. Each cylindrical cemented carbide bushing has 5 grooves, a groove depth of 0.15mm, a V-shaped groove, and a groove spacing of 0.5mm.

[0066] (4) First, place the cylindrical carbon fiber preform woven in step (2) into the split steel mold, and then precisely install the 5530 cylindrical hard alloy bushings with mechanical interlocking structure pre-processed in step (3) into the corresponding reserved holes of the cylindrical carbon fiber preform along the axial direction, so that the end face of all cylindrical hard alloy bushings is flush with the end face of the cylindrical carbon fiber preform. Then close the mold and lock it; wherein, all cylindrical hard alloy bushings are evenly distributed.

[0067] (5) First, the filler is surface-treated with a silane coupling agent to obtain a thermally conductive filler. Then, the thermally conductive filler is filled into a high-temperature resistant epoxy resin to obtain a high-temperature resistant epoxy resin filled with thermally conductive filler; wherein, the filling ratio of the thermally conductive filler is 55 wt%.

[0068] The obtained high-temperature resistant epoxy resin filled with thermally conductive filler has a thermal conductivity of 0.8 W / (m·K).

[0069] (6) Heat the mold to 100°C, and then inject the high-temperature resistant epoxy resin filled with thermally conductive filler into the mold cavity under an injection pressure of 0.5MPa. Keep it warm and pressurized for 30 minutes to allow the resin to fully impregnate the cylindrical carbon fiber preform and wrap the outer surface of the cylindrical hard alloy bushing.

[0070] (7) Heat the mold to 160°C and keep it under pressure for 2 hours to allow the resin to fully cure;

[0071] (8) After demolding, a composite syringe blank is obtained. Then, taking the outer circle of the base as the reference, the two end faces are precision machined. Then, the inner hole of the cylindrical carbide bushing is precision milled using a PCD tool to form a high-precision needle groove, and a lightweight wear-resistant composite material syringe for a composite needle circular weft machine is obtained. The cross-sectional shape of the needle groove is rectangular, the width of the needle groove is 2.2 mm, and the depth is 1.8 mm.

[0072] The final lightweight wear-resistant composite material needle cylinder for the composite needle circular knitting machine includes a matrix and wear-resistant parts; the matrix is ​​a cylindrical carbon fiber preform; the wear-resistant parts are 5530 cylindrical hard alloy bushings, whose outer surface is mechanically interlocked with the matrix, and whose inner surface forms a needle groove working surface for the movement of the knitting needles.

[0073] The wear-resistant part occupies 75% of the circumference of the lightweight wear-resistant composite material syringe barrel for composite needle circular weft knitting machines; the absolute value of the difference between the circumferential thermal expansion coefficients of the wear-resistant part and the matrix is ​​2.8 × 10⁻⁶. -6 / ℃;

[0074] Using the standard steel syringe of the QJZ126A-4 single-sided circular knitting machine from Shanghai No. 1 Textile Machinery as a comparison benchmark, the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine produced in this embodiment weighs only 45kg, a 72.7% reduction compared to the steel syringe (165kg). During continuous operation at 30rpm for 48 hours, the highest surface temperature of the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine in this embodiment remained stable at 68°C, with a temperature rise (ΔT) of only 17°C, far lower than that of the steel syringe (typically ΔT>40°C).

[0075] The needle groove wear depth of the cylindrical hard alloy bushing on the lightweight wear-resistant composite material syringe of the composite needle circular weft knitting machine is 4.8μm, which is much lower than that of the traditional nitrided steel syringe (usually >50μm).

[0076] Example 2

[0077] A method for preparing a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine, applicable to a high-speed single-sided weft knitting circular knitting machine with a syringe diameter of 34 inches and a gauge of E44, is disclosed below:

[0078] (1) Preparation of raw materials;

[0079] Carbon fiber: 24K carbon fiber, manufactured by Donghua Energy Co., Ltd., grade OEGQ4522;

[0080] Carbide: Free-cutting steel with an HRC of 69. The chemical composition of free-cutting steel by mass percentage includes: 0.5% carbon, 1.10% manganese, 0.2% chromium, 0.2% nickel, 0.3% copper, 0.06% sulfur, 0.04% phosphorus, with the balance being Fe and unavoidable impurities.

[0081] Filler: Boron nitride, with a large particle size D50 of 35 μm and a small particle size D50 of 1.5 μm;

[0082] Silane coupling agent: KH-550;

[0083] High-temperature resistant epoxy resin: Manufacturer is Jiangsu Sanmu Group Co., Ltd., brand name is SM-828-HT, glass transition temperature is 200℃;

[0084] (2) The carbon fiber is woven into a cylindrical carbon fiber preform with a thickness of 15mm using three-dimensional weaving technology. During the weaving process, 5530 mounting holes are reserved on the cylindrical carbon fiber preform for wear-resistant parts.

[0085] The woven cylindrical carbon fiber preform has a fiber volume fraction of 63% in the circumferential direction and 62% in the axial direction.

[0086] (3) First, 5530 cylindrical cemented carbide bushings with an outer diameter of Φ4.2mm and an inner diameter of Φ2.2mm (with a final milling allowance) are precision ground. Then, a raised texture is machined on the outer surface of each cylindrical cemented carbide bushing using a laser. The depth of the raised texture on each cylindrical cemented carbide bushing is 0.1mm.

[0087] (4) First, place the cylindrical carbon fiber preform woven in step (2) into the split steel mold, and then precisely install the 5530 cylindrical hard alloy bushings with mechanical interlocking structure pre-processed in step (3) into the corresponding reserved holes of the cylindrical carbon fiber preform along the axial direction, so that the end face of all cylindrical hard alloy bushings is flush with the end face of the cylindrical carbon fiber preform. Then close the mold and lock it; wherein, all cylindrical hard alloy bushings are evenly distributed.

[0088] (5) First, the filler is surface-treated with a silane coupling agent to obtain a thermally conductive filler. Then, the thermally conductive filler is filled into a high-temperature resistant epoxy resin to obtain a high-temperature resistant epoxy resin filled with thermally conductive filler; wherein, the filling ratio of the thermally conductive filler is 60 wt%.

[0089] The thermal conductivity of the obtained high-temperature resistant epoxy resin filled with thermally conductive filler is 0.9 W / (m·K);

[0090] (6) Heat the mold to 110°C, and then inject the high-temperature resistant epoxy resin filled with thermally conductive filler into the mold cavity under an injection pressure of 0.6MPa. Keep it warm and pressurized for 40 minutes to allow the resin to fully impregnate the cylindrical carbon fiber preform and wrap the outer surface of the cylindrical hard alloy bushing.

[0091] (7) Heat the mold to 170°C and keep it under pressure for 3 hours to allow the resin to fully cure.

[0092] (8) After demolding, a composite syringe blank is obtained. Then, taking the outer circle of the base as the reference, the two end faces are precision machined. Then, the inner hole of the cylindrical carbide bushing is precision milled using a PCD tool to form a high-precision needle groove, and a lightweight wear-resistant composite material syringe for a composite needle circular weft machine is obtained. The cross-sectional shape of the needle groove is rectangular, the width of the needle groove is 2.1 mm, and the depth is 1.8 mm.

[0093] The final lightweight wear-resistant composite material needle cylinder for the composite needle circular knitting machine includes a matrix and wear-resistant parts; the matrix is ​​a cylindrical carbon fiber preform; the wear-resistant parts are 5530 cylindrical hard alloy bushings, whose outer surface is mechanically interlocked with the matrix, and whose inner surface forms a needle groove working surface for the movement of the knitting needles.

[0094] The wear-resistant part occupies 80% of the circumference of the lightweight wear-resistant composite material syringe barrel used in composite needle circular knitting machines; the absolute value of the difference between the circumferential coefficients of thermal expansion between the wear-resistant part and the matrix is ​​2.5 × 10⁻⁶. -6 / ℃;

[0095] Using the standard steel syringe of the QJZ118A-4 single-sided circular knitting machine from Shanghai No. 1 Textile Machinery as a comparison benchmark, the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine produced in this embodiment weighs only 46 kg, which is 68.3% lighter than the steel syringe (145 kg). During continuous operation at 30 rpm for 48 hours, the highest surface temperature of the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine in this embodiment remained stable at 68°C, with a temperature rise (ΔT) of only 16°C, which is much lower than that of the steel syringe (usually ΔT>40°C).

[0096] The needle groove wear depth of the cylindrical hard alloy bushing on the lightweight wear-resistant composite material syringe of the composite needle circular weft knitting machine is 4μm, which is much lower than that of the traditional nitrided steel syringe (usually >50μm).

[0097] Example 3

[0098] A method for preparing a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine is disclosed. This method is applicable to a double-sided jacquard circular knitting machine with a barrel diameter of 34 inches and a gauge of E28. The syringe is a split-type composite syringe. The specific steps are as follows:

[0099] (1) Preparation of raw materials;

[0100] Carbon fiber: 24K carbon fiber, manufactured by Toray Industries, Inc. of Japan, grade T800S;

[0101] Hard alloy: Tungsten-cobalt alloy, HRC 70, cobalt content in the tungsten-cobalt alloy is 8wt%;

[0102] Filler: Boron nitride, with a large particle size D50 of 20 μm and a small particle size D50 of 5 μm;

[0103] Silane coupling agent: KH-550;

[0104] High-temperature resistant epoxy resin: Manufacturer is Momentive Advanced Materials (China) Co., Ltd., brand name is Eponex™ 1510, glass transition temperature is 205℃;

[0105] (2) The carbon fiber is woven into an upper ring and a lower ring using three-dimensional weaving technology. During the weaving process, 4800 mounting holes are reserved on the upper ring of the cylindrical carbon fiber preform for wear-resistant parts. The lower ring is a pure carbon fiber composite material structure. The thickness of the upper ring and the lower ring is 15mm.

[0106] The woven cylindrical carbon fiber preform has a fiber volume fraction of 65% in the circumferential direction and 63% in the axial direction.

[0107] (3) First, 4800 cylindrical cemented carbide bushings with an outer diameter of Φ4.1mm and an inner diameter of Φ2mm (with a final milling allowance) are precision ground. Then, a microporous structure is machined on the outer surface of each cylindrical cemented carbide bushing using a laser. The diameter of the microporous structure on each cylindrical cemented carbide bushing is 50μm and the depth is 0.2mm.

[0108] (4) First, place the upper and lower ring parts woven in step (2) into two open steel molds respectively. Then, accurately install the 4800 round tubular cemented carbide bushings with mechanical interlocking structure pre-processed in step (3) into the corresponding reserved holes of the upper ring part along the axial direction, so that the end face of all the round tubular cemented carbide bushings is flush with the end face of the upper ring part. Then close the mold and lock it. Among them, all the round tubular cemented carbide bushings are evenly distributed.

[0109] (5) First, the filler is surface-treated with a silane coupling agent to obtain a thermally conductive filler. Then, the thermally conductive filler is filled into a high-temperature resistant epoxy resin to obtain a high-temperature resistant epoxy resin filled with thermally conductive filler; wherein, the filling ratio of the thermally conductive filler is 65 wt%.

[0110] The thermal conductivity of the obtained high-temperature resistant epoxy resin filled with thermally conductive filler is 1 W / (m·K);

[0111] (6) Heat the two molds to 115°C, and then inject the high-temperature resistant epoxy resin filled with thermally conductive filler into the two mold cavities at an injection pressure of 0.7MPa. Keep the temperature and pressure for 50 minutes to allow the resin to fully impregnate the cylindrical carbon fiber preform and wrap the outer surface of the cylindrical hard alloy bushing.

[0112] (7) Heat the two molds to 180°C, keep them heated and pressurized for 2.5 hours to allow the resin to fully cure, and then take them out. Then connect and assemble them into a composite syringe blank by 12 M8×1.25 high-strength precision bolts evenly distributed in the circumference.

[0113] (8) After demolding, a composite syringe blank is obtained. Then, taking the outer circle of the base as the reference, the two end faces are precision machined. Then, the inner hole of the cylindrical carbide bushing is precision milled using a PCD tool to form a high-precision needle groove, and a lightweight wear-resistant composite material syringe for a composite needle circular weft machine is obtained. The cross-sectional shape of the needle groove is rectangular, the width of the needle groove is 2mm, and the depth is 1.9mm.

[0114] The final product is a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine. Figure 4 As shown, it includes a substrate 1 and a wear-resistant component 2;

[0115] The substrate 1 is a cylindrical carbon fiber preform; the cylindrical carbon fiber preform is composed of an upper ring 5 and a lower ring 6 connected by 12 M8×1.25 high-strength precision bolts evenly distributed around the circumference. The carbon fiber preform of the upper ring 5 has a wear-resistant bushing module corresponding to the E28 machine number embedded in it. The lower ring 6 is a pure carbon fiber composite material structure, which mainly plays the role of connection and transmission.

[0116] The wear-resistant part 2 consists of 4,800 cylindrical hard alloy bushings. Its outer surface is mechanically interlocked with the base 1, and its inner surface forms a needle groove 4 working surface for the movement of the knitting needles.

[0117] The area where wear-resistant part 2 is located occupies 85% of the circumference of the lightweight wear-resistant composite material syringe barrel for composite needle circular weft knitting machines; the absolute value of the difference between the circumferential coefficients of thermal expansion of wear-resistant part 2 and the matrix 1 is 3.0 × 10⁻⁶. -6 / ℃;

[0118] Compared to the standard steel syringe of the Mayer & Cie. OVJA 2.4 E double-sided jacquard circular knitting machine (34-inch cylinder diameter, machine number E28), the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine produced in this embodiment weighs only 49 kg, a 51.0% reduction compared to the steel syringe (100 kg). During continuous operation at 30 rpm for 48 hours, the highest surface temperature of the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine in this embodiment remained stable at 68°C, with a temperature rise (ΔT) of only 18°C, far lower than that of the steel syringe (typically ΔT>40°C).

[0119] The wear depth of the needle groove on the cylindrical hard alloy bushing of the lightweight wear-resistant composite material syringe used in composite needle circular knitting machines is 3μm, which is much lower than that of traditional nitrided steel syringes (usually >50μm).

[0120] Example 4

[0121] A method for preparing a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine, applicable to a high-speed single-sided weft knitting circular knitting machine with a syringe diameter of 30 inches and a machine size of E22, is disclosed below:

[0122] (1) Preparation of raw materials;

[0123] Carbon fiber: 24K carbon fiber, manufactured by Zhongfu Shenying Carbon Fiber Co., Ltd., grade SYT49;

[0124] Hard alloy: Tungsten-cobalt alloy, HRC 69, cobalt content in the tungsten-cobalt alloy is 6wt%;

[0125] Filler: Aluminum nitride, with a large particle size D50 of 45 μm and a small particle size D50 of 2 μm;

[0126] Silane coupling agent: KH-560;

[0127] High-temperature resistant epoxy resin: Manufacturer is Huntsman Advanced Materials, grade is Araldite® LY1564 / Aradur®3486, glass transition temperature is 210℃;

[0128] (2) The carbon fiber is woven into a cylindrical carbon fiber preform with a thickness of 10 mm using three-dimensional weaving technology. During the weaving process, 6100 mounting holes are reserved on the cylindrical carbon fiber preform for wear-resistant parts.

[0129] The woven cylindrical carbon fiber preform has a fiber volume fraction of 62% in the circumferential direction and 65% in the axial direction.

[0130] (3) First, 6100 cylindrical cemented carbide bushings with an outer diameter of Φ4mm and an inner diameter of Φ2.1mm (with a final milling allowance) are precision ground. Then, grooves are machined on the outer surface of each cylindrical cemented carbide bushing using a laser. Each cylindrical cemented carbide bushing has 5 grooves, a groove depth of 0.15mm, a V-shaped groove, and a groove spacing of 0.5mm.

[0131] (4) First, place the cylindrical carbon fiber preform woven in step (2) into the split steel mold, and then precisely install the 6100 cylindrical hard alloy bushings with mechanical interlocking structure pre-processed in step (3) into the corresponding reserved holes of the cylindrical carbon fiber preform along the axial direction, so that the end face of all cylindrical hard alloy bushings is flush with the end face of the cylindrical carbon fiber preform. Then close the mold and lock it; wherein, all cylindrical hard alloy bushings are evenly distributed.

[0132] (5) First, the filler is surface-treated with a silane coupling agent to obtain a thermally conductive filler. Then, the thermally conductive filler is filled into a high-temperature resistant epoxy resin to obtain a high-temperature resistant epoxy resin filled with thermally conductive filler; wherein, the filling ratio of the thermally conductive filler is 70 wt%.

[0133] The thermal conductivity of the high-temperature resistant epoxy resin filled with thermally conductive filler is 1.1 W / (m·K).

[0134] (6) Heat the mold to 120°C, and then inject the high-temperature resistant epoxy resin filled with thermally conductive filler into the mold cavity under an injection pressure of 0.8MPa. Keep it warm and pressurized for 60 minutes to allow the resin to fully impregnate the cylindrical carbon fiber preform and wrap the outer surface of the cylindrical hard alloy bushing.

[0135] (7) Heat the mold to 170°C and keep it under pressure for 2 hours to allow the resin to fully cure.

[0136] (8) After demolding, a composite syringe blank is obtained. Then, taking the outer circle of the base as the reference, the two end faces are precision machined. Then, the inner hole of the cylindrical carbide bushing is precision milled using a PCD tool to form a high-precision needle groove, and a lightweight wear-resistant composite material syringe for a composite needle circular weft machine is obtained. The cross-sectional shape of the needle groove is rectangular, the width of the needle groove is 2.1 mm, and the depth is 1.8 mm.

[0137] The final product is a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine. Figures 1-3 As shown, it includes a substrate 1 and a wear-resistant component 2; the substrate 1 is a cylindrical carbon fiber preform; the wear-resistant component 2 consists of 6100 cylindrical hard alloy bushings, the outer surface of which is mechanically interlocked with the substrate 1, the interlocking structure being a V-groove 3, and the inner surface forming a needle groove 4 working surface for the movement of knitting needles.

[0138] The area where wear-resistant part 2 is located accounts for 90% of the circumference of the lightweight wear-resistant composite material syringe barrel for composite needle circular weft knitting machines; the absolute value of the difference between the circumferential thermal expansion coefficients of wear-resistant part 2 and the matrix 1 is 2.9 × 10⁻⁶. -6 / ℃;

[0139] Using the standard steel syringe of the QJZ106C-2 single-sided circular knitting machine from Shanghai No. 1 Textile Machinery as a comparison benchmark, the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine produced in this embodiment weighs only 43kg, a 62.9% reduction compared to the steel syringe (116kg). During continuous operation at 30rpm for 48 hours, the highest surface temperature of the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine in this embodiment remained stable at 68°C, with a temperature rise (ΔT) of only 15°C, far lower than that of the steel syringe (typically ΔT>40°C).

[0140] The needle groove wear depth of the cylindrical hard alloy bushing on the lightweight wear-resistant composite material syringe of the composite needle circular weft knitting machine is 5μm, which is much lower than that of the traditional nitrided steel syringe (usually >50μm).

[0141] Example 5

[0142] A method for preparing a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine, applicable to a high-speed single-sided weft knitting circular knitting machine with a syringe diameter of 40 inches and a gauge of E28, is disclosed below.

[0143] (1) Preparation of raw materials;

[0144] Carbon fiber: 24K carbon fiber, manufactured by Toray Industries, Inc. of Japan, grade T700S;

[0145] Carbide: Free-cutting steel with an HRC of 68. The chemical composition of free-cutting steel by mass percentage includes: 0.5% carbon, 1.20% manganese, 0.2% chromium, 0.2% nickel, 0.3% copper, 0.07% sulfur, 0.04% phosphorus, with the balance being Fe and unavoidable impurities.

[0146] Filler: Boron nitride, with a large particle size D50 of 30 μm and a small particle size D50 of 4 μm;

[0147] Silane coupling agent: KH-560;

[0148] High-temperature resistant epoxy resin: Manufacturer is D.E. (China) Investment Co., Ltd., brand name is HP-4710, glass transition temperature is 253℃;

[0149] (2) The carbon fiber is woven into a cylindrical carbon fiber preform with a thickness of 20mm using three-dimensional weaving technology. During the weaving process, 5250 mounting holes are reserved on the cylindrical carbon fiber preform for wear-resistant parts.

[0150] The woven cylindrical carbon fiber preform has a fiber volume fraction of 64% in the circumferential direction and 62% in the axial direction.

[0151] (3) First, 5250 cylindrical cemented carbide bushings with an outer diameter of Φ4.2mm and an inner diameter of Φ2mm (with a final milling allowance) are precision ground. Then, a raised texture is machined on the outer surface of each cylindrical cemented carbide bushing using a laser. The depth of the raised texture on each cylindrical cemented carbide bushing is 0.08mm.

[0152] (4) First, place the cylindrical carbon fiber preform woven in step (2) into the split steel mold, and then precisely install the 5250 cylindrical hard alloy bushings with mechanical interlocking structure pre-processed in step (3) into the corresponding reserved holes of the cylindrical carbon fiber preform along the axial direction, so that the end face of all cylindrical hard alloy bushings is flush with the end face of the cylindrical carbon fiber preform. Then close the mold and lock it; wherein, all cylindrical hard alloy bushings are evenly distributed.

[0153] (5) First, the filler is surface-treated with a silane coupling agent to obtain a thermally conductive filler. Then, the thermally conductive filler is filled into a high-temperature resistant epoxy resin to obtain a high-temperature resistant epoxy resin filled with thermally conductive filler; wherein, the filling ratio of the thermally conductive filler is 75 wt%.

[0154] The thermal conductivity of the high-temperature resistant epoxy resin filled with thermally conductive filler is 1.2 W / (m·K).

[0155] (6) Heat the mold to 110°C, and then inject the high-temperature resistant epoxy resin filled with thermally conductive filler into the mold cavity under an injection pressure of 0.5MPa. Keep it warm and pressurized for 30 minutes to allow the resin to fully impregnate the cylindrical carbon fiber preform and wrap the outer surface of the cylindrical hard alloy bushing.

[0156] (7) Heat the mold to 160°C and keep it under pressure for 3 hours to allow the resin to fully cure.

[0157] (8) After demolding, a composite syringe blank is obtained. Then, taking the outer circle of the base as the reference, the two end faces are precision machined. Then, the inner hole of the cylindrical carbide bushing is precision milled using a PCD tool to form a high-precision needle groove, and a lightweight wear-resistant composite material syringe for a composite needle circular weft machine is obtained. The cross-sectional shape of the needle groove is rectangular, the width of the needle groove is 2.2 mm, and the depth is 1.9 mm.

[0158] The final lightweight wear-resistant composite material needle cylinder for the composite needle circular knitting machine includes a matrix and wear-resistant parts; the matrix is ​​a cylindrical carbon fiber preform; the wear-resistant parts are 5250 cylindrical hard alloy bushings, whose outer surface is mechanically interlocked with the matrix, and whose inner surface forms a needle groove working surface for the movement of the knitting needles.

[0159] The wear-resistant part occupies 80% of the circumference of the lightweight wear-resistant composite material syringe barrel for composite needle circular weft knitting machines; the absolute value of the difference between the circumferential thermal expansion coefficients of the wear-resistant part and the matrix is ​​2.8 × 10⁻⁶. -6 / ℃;

[0160] Using the standard steel syringe of the QJZ132B-2 single-sided circular knitting machine from Shanghai No. 1 Textile Machinery as a comparison benchmark, the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine produced in this embodiment weighs only 44kg, a 68.6% reduction compared to the steel syringe (140kg). During continuous operation at 30rpm for 48 hours, the highest surface temperature of the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine in this embodiment remained stable at 68°C, with a temperature rise (ΔT) of only 17°C, far lower than that of the steel syringe (typically ΔT>40°C).

[0161] The needle groove wear depth of the cylindrical hard alloy bushing on the lightweight wear-resistant composite material syringe of the composite needle circular weft knitting machine is 4μm, which is much lower than that of the traditional nitrided steel syringe (usually >50μm).

[0162] Example 6

[0163] A method for preparing a lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine is disclosed. This method is applicable to a double-sided jacquard circular knitting machine with a barrel diameter of 34 inches and a gauge of E28. The syringe is a split-type composite syringe. The specific steps are as follows:

[0164] (1) Preparation of raw materials;

[0165] Carbon fiber: 24K carbon fiber, manufactured by Toray Industries, Inc. of Japan, grade T800S;

[0166] Hard alloy: Tungsten-cobalt alloy, HRC 70, cobalt content in the tungsten-cobalt alloy is 8wt%;

[0167] The filler is composed of large-particle-size boron nitride (D50 = 20μm) and small-particle-size aluminum nitride (D50 = 5μm) in a mass ratio of 7:3.

[0168] Silane coupling agent: KH-550;

[0169] High-temperature resistant epoxy resin: Manufacturer is Momentive Advanced Materials (China) Co., Ltd., brand name is Eponex™ 1510, glass transition temperature is 205℃;

[0170] (2) The carbon fiber is woven into an upper ring and a lower ring using three-dimensional weaving technology. During the weaving process, 4800 mounting holes are reserved on the upper ring of the cylindrical carbon fiber preform for wear-resistant parts. The lower ring is a pure carbon fiber composite material structure. The thickness of the upper ring and the lower ring is 15mm.

[0171] The woven cylindrical carbon fiber preform has a fiber volume fraction of 65% in the circumferential direction and 63% in the axial direction.

[0172] (3) First, 4800 cylindrical cemented carbide bushings with an outer diameter of Φ4.1mm and an inner diameter of Φ2mm (with a final milling allowance) are precision ground. Then, a microporous structure is machined on the outer surface of each cylindrical cemented carbide bushing using a laser. The diameter of the microporous structure on each cylindrical cemented carbide bushing is 50μm and the depth is 0.2mm.

[0173] (4) First, place the upper and lower ring parts woven in step (2) into two open steel molds respectively. Then, accurately install the 4800 round tubular cemented carbide bushings with mechanical interlocking structure pre-processed in step (3) into the corresponding reserved holes of the upper ring part along the axial direction, so that the end face of all the round tubular cemented carbide bushings is flush with the end face of the upper ring part. Then close the mold and lock it. Among them, all the round tubular cemented carbide bushings are evenly distributed.

[0174] (5) First, the filler is surface-treated with a silane coupling agent to obtain a thermally conductive filler. Then, the thermally conductive filler is filled into a high-temperature resistant epoxy resin to obtain a high-temperature resistant epoxy resin filled with thermally conductive filler; wherein, the filling ratio of the thermally conductive filler is 65 wt%.

[0175] The thermal conductivity of the high-temperature resistant epoxy resin filled with thermally conductive filler is 1.32 W / (m·K).

[0176] (6) Heat the two molds to 115°C, and then inject the high-temperature resistant epoxy resin filled with thermally conductive filler into the two mold cavities at an injection pressure of 0.7MPa. Keep the temperature and pressure for 50 minutes to allow the resin to fully impregnate the cylindrical carbon fiber preform and wrap the outer surface of the cylindrical hard alloy bushing.

[0177] (7) Heat the two molds to 180°C, keep them heated and pressurized for 2.5 hours to allow the resin to fully cure, and then take them out. Then connect and assemble them into a composite syringe blank by 12 M8×1.25 high-strength precision bolts evenly distributed in the circumference.

[0178] (8) After demolding, a composite syringe blank is obtained. Then, taking the outer circle of the base as the reference, the two end faces are precision machined. Then, the inner hole of the cylindrical carbide bushing is precision milled using a PCD tool to form a high-precision needle groove, and a lightweight wear-resistant composite material syringe for a composite needle circular weft machine is obtained. The cross-sectional shape of the needle groove is rectangular, the width of the needle groove is 2mm, and the depth is 1.9mm.

[0179] The final composite needle cylinder for circular knitting machines, made of lightweight and wear-resistant composite materials, includes a matrix and wear-resistant components.

[0180] The matrix is ​​a cylindrical carbon fiber preform; the cylindrical carbon fiber preform is composed of an upper ring and a lower ring connected by 12 M8×1.25 high-strength precision bolts evenly distributed around the circumference. The upper ring of the carbon fiber preform has a wear-resistant bushing module corresponding to the E28 machine number embedded in it, and the lower ring is a pure carbon fiber composite material structure, which mainly plays the role of connection and transmission.

[0181] The wear-resistant part 2 consists of 4,800 cylindrical hard alloy bushings. Its outer surface is mechanically interlocked with the base 1, and its inner surface forms a needle groove 4 working surface for the movement of the knitting needles.

[0182] The area where wear-resistant part 2 is located accounts for 80% of the circumference of the lightweight wear-resistant composite material syringe barrel for composite needle circular weft knitting machines; the absolute value of the difference between the circumferential thermal expansion coefficients of wear-resistant part 2 and the matrix 1 is 2.8 × 10⁻⁶. -6 / ℃;

[0183] Compared to the standard steel syringe of the Mayer & Cie. OVJA 2.4 E double-sided jacquard circular knitting machine (34-inch cylinder diameter, machine number E28), the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine produced in this embodiment weighs only 44 kg, a 56.0% reduction compared to the steel syringe (100 kg). During continuous operation at 30 rpm for 48 hours, the highest surface temperature of the lightweight wear-resistant composite material syringe for the composite needle circular knitting machine in this embodiment remained stable at 63°C, with a temperature rise (ΔT) of only 13°C, far lower than that of the steel syringe (typically ΔT>40°C).

[0184] The needle groove wear depth of the cylindrical hard alloy bushing on the lightweight wear-resistant composite material syringe of the composite needle circular weft knitting machine is 2.4μm, which is much lower than that of the traditional nitrided steel syringe (usually >50μm).

[0185] In addition, thanks to the synergistic filling effect of large-particle boron nitride and small-particle aluminum nitride, the thermally conductive network of the resin matrix is ​​denser and the interfacial thermal resistance is lower, which reduces the thermal deformation of the entire bobbin under high-speed operation by 37.5% (measured radial runout ≤0.05mm), effectively ensuring the synchronization accuracy and loop formation stability of the high-gauge (E28) knitting needle movement.

Claims

1. A lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine, characterized in that: It includes a matrix and wear-resistant parts. The matrix is ​​a cylindrical carbon fiber preform, and the wear-resistant parts are multiple cylindrical cemented carbide bushings with an HRC ≥ 68. The substrate has pre-drilled mounting holes, and the wear-resistant parts are embedded into the substrate axially through the pre-drilled mounting holes. The RTM process is used to achieve integrated composite molding. The outer surface of the wear-resistant part is mechanically interlocked with the substrate, and the inner surface forms a needle groove working surface for the movement of the knitting needle.

2. The lightweight wear-resistant composite material syringe for a composite needle circular knitting machine according to claim 1, characterized in that, The cylindrical carbon fiber preform is obtained through three-dimensional weaving, with mounting holes reserved for wear-resistant parts during the weaving process; The volume fraction of fibers in the cylindrical carbon fiber preform is not less than 60% in both the circumferential and axial directions.

3. The lightweight wear-resistant composite material syringe for a composite needle circular knitting machine according to claim 1, characterized in that, The number of cylindrical cemented carbide bushings is 4,000 to 6,500, and the multiple cylindrical cemented carbide bushings are evenly distributed.

4. The lightweight wear-resistant composite material syringe for a composite needle circular knitting machine according to claim 3, characterized in that, The wear-resistant parts occupy 75-90% of the circumference of the lightweight wear-resistant composite material syringe barrel used in composite needle circular knitting machines.

5. A lightweight, wear-resistant composite material syringe for a composite needle circular knitting machine according to claim 3, characterized in that, Hard alloys are tungsten-cobalt alloys or free-cutting steels; The cobalt content in tungsten-cobalt alloys is 6-16 wt%. The chemical composition of free-cutting steel, by mass percentage, includes: carbon ≤0.5%, manganese 1.00~1.30%, chromium ≤0.2%, nickel ≤0.2%, copper ≤0.3%, sulfur 0.04~0.09%, phosphorus ≤0.04%, with the balance being Fe and unavoidable impurities.

6. The lightweight wear-resistant composite material syringe for a composite needle circular knitting machine according to claim 1, characterized in that, The absolute value of the difference between the coefficients of thermal expansion of the wear-resistant part and the substrate in the circumferential direction shall not exceed 3.0 × 10⁻⁶. -6 / ℃.

7. A method for preparing a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine as described in any one of claims 1 to 6, characterized in that... Includes the following steps: (1) A cylindrical carbon fiber preform is woven using three-dimensional weaving technology, and during the weaving process, mounting holes are reserved on the cylindrical carbon fiber preform for wear-resistant parts; (2) A mechanical interlocking structure is machined on the outer surface of a cylindrical hard alloy bushing using a laser; (3) First, put the cylindrical carbon fiber preform woven in step (1) into the split steel mold, and then accurately install the multiple cylindrical hard alloy bushings with mechanical interlocking structure pre-processed in step (2) into the reserved holes of the cylindrical carbon fiber preform, so that the end face of all the cylindrical hard alloy bushings is flush with the end face of the cylindrical carbon fiber preform. Then close the mold and lock it. (4) Heat the mold to 100~120℃, then inject the high-temperature resistant epoxy resin filled with thermally conductive filler into the mold cavity under an injection pressure of 0.5~0.8MPa, and keep it at the temperature and pressure for 30~60min to allow the resin to fully impregnate the cylindrical carbon fiber preform and wrap the outer surface of the cylindrical hard alloy bushing; the glass transition temperature of the high-temperature resistant epoxy resin is not lower than 150℃, the thermal conductivity of the high-temperature resistant epoxy resin filled with thermally conductive filler is not lower than 0.8W / (m·K), and the filling ratio of the thermally conductive filler is 55~75wt%; (5) Heat the mold to 160~180℃ and keep it under pressure for 2~3 hours to allow the resin to fully cure; (6) After demolding, a composite syringe blank is obtained. The composite syringe blank is then precision machined to obtain a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine.

8. The method for preparing a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine according to claim 7, characterized in that, The thermally conductive filler is aluminum nitride and / or boron nitride surface-treated with silane coupling agent; the filling ratio of the thermally conductive filler is 60~70wt%.

9. The method for preparing a lightweight wear-resistant composite material syringe for a composite needle circular knitting machine according to claim 8, characterized in that, The process of precision machining of composite syringe blanks is as follows: first, the two end faces are precision machined with the outer circle of the base as the reference; then, the inner hole of the cylindrical carbide bushing is precision milled using PCD tools to form a high-precision needle groove.

Images