A partition-strengthened compound structure cam for a compound needle circular weft knitting machine and a forming method thereof

Abstract

The present application belongs to the technical field of textile machinery, and discloses a partition-strengthened composite structure cam for a compound needle circular weft knitting machine and a forming method thereof. The partition-strengthened composite structure cam for the compound needle circular weft knitting machine comprises a working surface area, a toughness transition area and a mounting base area. The working surface area, the toughness transition area and the mounting base area respectively adopt high-carbon high-chromium free-cutting steel, medium-carbon medium-chromium free-cutting steel and low-carbon low-chromium free-cutting steel. The preparation method comprises the following steps: first, a precision die is designed according to a three-dimensional model of the cam, a die cavity is isolated into the working surface area, the toughness transition area and the mounting base area according to functions, and free-cutting steel powder with corresponding components is accurately filled into each die cavity; then, cold isostatic pressing forming, high-temperature vacuum sintering, heat treatment and finishing are performed to obtain the partition-strengthened composite structure cam for the compound needle circular weft knitting machine. The present application systematically solves the technical problem that the traditional cam is difficult to simultaneously consider high wear resistance, high impact resistance and excellent processing workability, and significantly improves the service life and reliability of the cam.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of textile machinery and relates to a partition-strengthened composite structure cam for a composite needle circular weft knitting machine and a forming method thereof. BACKGROUND

[0002] As a key loop-forming component, the performance of the cam of a weft knitting large circular machine directly affects the speed, efficiency and fabric quality of the knitting machine. With the development of knitting equipment towards high gauge and high speed, the working environment of the cam is increasingly harsh. On the one hand, the speed of the knitting needle on the cam track can reach 30-40 m / s, and the knitting needle needs to bear thousands of high-frequency and high-strain cyclic impact loads per minute, which is prone to generate fatigue cracks at stress concentration sites. On the other hand, the severe friction between the knitting needle and the working surface of the cam can cause serious wear. Especially under the condition of high gauge, the machining precision of the working surface of the cam is required to be extremely high (the tolerance is usually controlled within ±0.01 mm), and micron-level wear can cause the dynamic trajectory of the needle hook to deviate, resulting in needle collision, needle missing and other problems, which seriously affect the fabric quality.

[0003] In the prior art, related patents provide various technical solutions, but all have certain limitations.

[0004] The patent application with the application publication number CN120624882A discloses a copper-based powder metallurgy friction material and a preparation method thereof. The method significantly improves the friction stability, wear resistance and heat decay resistance of the copper-based friction material under high-speed heavy-load conditions (such as 400 km / h braking) through unique multi-component design (such as adding chromium iron, nickel-coated tungsten disulfide, etc.) and process optimization. However, the overall composition of the material is single and uniform, which cannot realize functional partitioning (such as high wear resistance on the friction surface and high thermal conductivity in the matrix), limiting the performance breakthrough under more complex working conditions. This "one-size-fits-all" design approach cannot meet the evolutionary needs of modern high-end equipment for gradient and multi-functional integration of friction materials.

[0005] The patent with the authorization publication number CN104384503B discloses an iron-copper-based powder metallurgy antifriction material and a preparation method thereof. The method prepares a composite material with wear resistance and low friction coefficient by adding various components (such as bronze powder, aluminum oxide, fluorinated graphite, etc.). The method shows the flexibility of powder metallurgy technology in material composition design, but the composition design is uniformly mixed, resulting in isotropic homogeneous material. Moreover, the material does not involve the technology of realizing composition gradient change through partition powder loading, so it cannot manufacture integrated cam components with significant performance differences in different areas of the same part, and cannot fundamentally solve the problem of differentiated needs of different functional areas of the cam for material performance.

[0006] Patent with authorization announcement No. CN101755060B discloses a functionally segmented powder metal component, which realizes lightweight and performance optimization of the part and avoids cost and process problems caused by using multiple materials or complex assembly by manufacturing functionally segmented, performance different regions such as high strength region and high wear resistance region on the same powder metallurgical component through single material powder and differential subsequent processing such as selective cooling or heat treatment. However, it also has limitations: process control is complex, precision of heat treatment or cooling is extremely high, and it is difficult to ensure uniformity and stability of performance of different regions; and it may not be suitable for occasions requiring extreme performance difference.

[0007] Patent with authorization announcement No. CN104017965B discloses a strengthening and toughening heat treatment method of Cr12MoV steel, which aims to improve hardness, impact toughness and wear resistance of the steel by optimizing quenching temperature and adopting deep cryogenic treatment and subsequent tempering process. The method improves the problem of insufficient toughness of traditional Cr12MoV steel to some extent, but its essence is still the overall heat treatment of single homogeneous material. For the triangular structure with complex structure and different performance requirements of different parts, the method cannot realize the coordination of ultra-high wear resistance of the working surface and high impact resistance of the matrix, and the performance improvement is limited.

[0008] Patent application with application announcement No. CN103882370A discloses a soft nitriding surface treatment method of 42CrMo steel rotary drive part, which forms a high-hardness compound layer on the surface of the part by nitrocarburizing to improve the surface wear resistance and fatigue strength. However, the surface strengthening layer is usually thin (usually only a few microns to tens of microns), and under the condition of continuous strong impact and wear of high-speed knitting needles, there is a risk of peeling of the layer and insufficient durability. Once the protective layer fails, the wear resistance will decrease sharply, and the process cannot improve the toughness and processing performance of the core of the part.

[0009] Therefore, there is an urgent need for a partitioned reinforced composite structure triangular for a compound needle circular weft knitting machine and a forming method thereof, which can break through the performance limitations of a single material system, realize the coordinated optimization of high wear resistance of the working surface, high toughness of the transition zone and excellent processing performance of the installation zone, and fundamentally solve the harsh requirements of high-speed weft knitting large circular machines on the comprehensive performance of the triangular part. SUMMARY

[0010] The purpose of the present application is to solve the problems existing in the prior art and provide a partitioned reinforced composite structure triangular for a compound needle circular weft knitting machine and a forming method thereof.

[0011] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0012] A partitioned reinforced composite structure cam for a compound needle circular weft knitting machine, comprising a working surface area, a toughness transition area and a mounting base area;

[0013] The working surface area can directly bear the impact and friction of the knitting needle, and high-carbon high-chromium free-cutting steel is adopted to ensure that a sufficient amount of hard carbide (such as M7C3 and MC type carbide) is formed to provide excellent wear resistance; the toughness transition area surrounds and supports the working surface area, and medium-carbon medium-chromium free-cutting steel is adopted, the amount of carbide is moderate, the toughness of the base is improved, and the impact energy of the knitting needle can be effectively absorbed to prevent cracks from expanding from the working surface area with high hardness; the mounting base area constitutes the main frame and the mounting and fixing part of the cam, and low-carbon low-chromium free-cutting steel is adopted to significantly improve the cutting performance of the material, facilitate mechanical processing operations such as drilling and tapping, and improve manufacturing efficiency; the chemical composition of the high-carbon high-chromium free-cutting steel contains Mo and S elements, and the appropriate amount of sulfur element improves the cutting machinability of the material, facilitates final precision grinding, and avoids cracks during processing; the chemical composition of the medium-carbon medium-chromium free-cutting steel contains Mo element; the chemical composition of the low-carbon low-chromium free-cutting steel contains Ca and S elements, which significantly improves the cutting property while ensuring firm combination with the transition area through sintering;

[0014] The working surface area, the toughness transition area and the mounting base area are obtained by integrated forming, and the three functional areas are not simply mechanically combined, but are metallurgically combined at the atomic diffusion level through the powder metallurgy process of partitioned powder loading and precision sintering, and an integrated structure with continuous gradient transition of composition and performance is formed at the combination interface, which avoids stress concentration caused by performance mutation and improves the reliability of the overall structure, thereby fundamentally solving the performance contradiction of each area; near the interface from the working surface area to the toughness transition area (i.e. the transition zone within a certain width range on both sides of the interface), the contents of C, Cr and Mo are continuously distributed from high to low; near the interface from the toughness transition area to the mounting base area, the contents of C and Cr are continuously distributed from high to low.

[0015] The shape and structure of the cam of the present application are the same as those of the prior art, and all include three functional parts of working surface, transition area and mounting area, which are determined by the basic requirements of the motion trajectory of the knitting needle of the circular weft knitting machine and the fixed installation. However, the cam of the prior art is often treated as a homogeneous whole, and a single material (such as Cr12MoV steel) is used to improve performance through overall heat treatment or surface treatment (such as nitriding), which exactly leads to the performance bottleneck. The unique feature of the present application is the "partitioned reinforcement" design of the internal material structure and the integrated forming process. Based on the understanding of the stress state and failure mechanism of the different functional areas inside the cam, the present application creatively proposes the design concept of "function matching and gradient transition" at the material design and manufacturing level, and precisely partitions the traditional cam into functional areas. The internal material distribution and performance are continuously graded, thereby realizing the performance improvement.

[0016] In traditional triangular alloys, increasing hardness often sacrifices toughness, leading to brittle fracture. In this invention, the working surface hardness reaches HRC 62-64, while the impact toughness in the transition zone is no less than 25 J (good impact resistance). Bench tests show that the wear resistance is more than 2.5 times that of the traditional Cr12MoV triangular alloy, and the impact fatigue resistance is improved by more than 50%. This simultaneous achievement of high hardness and high toughness is difficult to attain with existing technologies.

[0017] The superior machinability of the mounting area in this invention (increasing machining efficiency by 40%) reduces manufacturing costs, while the gradient transition combined with the high-toughness zone avoids interface cracking caused by machining stress. The overall structure exhibits no stress concentration under high-speed impact, significantly improving reliability.

[0018] As a preferred technical solution:

[0019] The composite needle circular knitting machine with a triangular reinforced composite structure as described above uses high-carbon, high-chromium free-cutting steel with the following chemical composition by mass percentage: C: 0.95~1.10%, Cr: 5.5~6.5%, Mo: 0.8~1.2%, V: 0.2~0.4%, Mn: ≤0.6%, Si: ≤0.6%, S: 0.10~0.14%, with the balance being Fe and unavoidable impurities. The high-carbon, high-chromium free-cutting steel used in the working area, after vacuum oil quenching and multiple deep cryogenic tempering treatments, has a metallographic structure consisting of a tempered martensitic matrix with uniformly distributed M7C3 and MC type carbides. Its macroscopic hardness can reach HRC 62~64, and its impact toughness (AKU) is not less than 8J.

[0020] The composite needle circular knitting machine with a triangular partitioned reinforced composite structure, as described above, uses medium-carbon, medium-chromium free-cutting steel with the following chemical composition by mass percentage: C: 0.45~0.55%, Cr: 2.5~3.5%, Mo: 0.4~0.6%, Mn: 0.6~0.9%, Si: 0.2~0.4%, S: 0.06~0.09%, with the balance being Fe and unavoidable impurities. The medium-carbon, medium-chromium free-cutting steel used in the toughness transition zone has a hardness controlled at HRC 52~54 after heat treatment, and its impact toughness (AKU) is significantly higher than that of the working surface zone, not less than 25J, effectively acting as a resistance zone for crack propagation.

[0021] The chemical composition of the low-carbon low-chromium free-cutting steel according to the low-carbon low-chromium free-cutting steel of the composite needle circular weft knitting machine partitioned reinforced composite structure cam as described above, by mass percentage, is: C: 0.15~0.25%, Cr: 0.8~1.2%, Mn: 0.9~1.2%, S: 0.24~0.28%, Ca: 0.002~0.006%, and the balance is Fe and inevitable impurities; the low-carbon low-chromium free-cutting steel used for the installation base area has a hardness of HRC 28~32 after heat treatment, and the relative cutting machinability (with 45 steel as 100%) can reach 150~180%, and the subsequent processing such as drilling and tapping is extremely easy.

[0022] The C content gradually decreases from 0.95~1.10% to 0.45~0.55%, the Cr content gradually decreases from 5.5~6.5% to 2.5~3.5%, and the Mo content gradually decreases from 0.8~1.2% to 0.4~0.6% along a transition zone of 50~200 microns wide on both sides of the interface from the working surface area to the toughness transition area of the composite needle circular weft knitting machine partitioned reinforced composite structure cam as described above.

[0023] The C content gradually decreases from 0.45~0.55% to 0.15~0.25%, and the Cr content gradually decreases from 2.5~3.5% to 0.8~1.2% along a transition zone of 50~200 microns wide on both sides of the interface from the toughness transition area to the installation base area.

[0024] The present application also provides a forming method of the composite needle circular weft knitting machine partitioned reinforced composite structure cam as described above, first, a precision die is designed according to the three-dimensional model of the cam, the die cavity is isolated into three independent powder cavities of the working surface area, the toughness transition area and the installation base area in turn according to the function, and the free-cutting steel powder of the corresponding composition is accurately filled into each powder cavity; then, cold isostatic pressing, high-temperature vacuum sintering, heat treatment and finishing are sequentially performed to obtain the composite needle circular weft knitting machine partitioned reinforced composite structure cam.

[0025] The temperature of the high-temperature vacuum sintering is above 1250℃.

[0026] First, the free-cutting steel powders of different formulations are separated and compacted by a partition, and then the partition is removed for high-temperature sintering. In an environment above 1250℃, the metal atoms (such as Cr) and C atoms on both sides will actively penetrate and migrate, and after a long time of heat preservation, a fusion zone with continuous and gradual changes in composition and performance is generated at the original interface, so that the different parts are truly metallurgically combined into a whole.

[0027] As a preferred technical solution:

[0028] The forming method of the composite needle circular weft knitting machine partitioned reinforced composite structure cam as described above has the following specific steps:

[0029] (1) Mould design and powder filling: According to the three-dimensional model of the cam, a precision mould is designed, and the mould cavity is divided into three independent powder cavities, namely, the working surface area, the toughness transition area and the mounting base area, in sequence by the partition plate. The corresponding components of the free-cutting steel powder are accurately filled into each powder cavity, and the powder stacking density of each area is ensured to be uniform;

[0030] (2) Cold isostatic pressing: Two-way pressing is carried out under the pressure of 300-600 MPa to obtain the cam green body with high density and high strength;

[0031] (3) High-temperature vacuum sintering: The cam green body is placed in a vacuum sintering furnace at 1250-1280℃, and the temperature is maintained for 90-120 minutes. In this process, since the components of the free-cutting steel in each area are not independently selected but are matched based on the overall performance, the powders in different areas are firmly metallurgically combined through atomic diffusion (i.e., interaction and atomic diffusion behavior between the powders in each area), and a composition gradient transition zone with a width of 50-200 μm is formed at the interface, realizing perfect composition gradient transition and metallurgical bonding. After effectively eliminating the stress concentration caused by performance mutation, the sintered blank is obtained;

[0032] (4) Heat treatment and finishing: The sintered blank is first heat treated, and then the working track of the working surface of the heat-treated sintered blank is ground and polished to make the surface roughness Ra ≤ 0.2 μm to meet the running requirements of the high-gauge knitting needle, thereby obtaining the partition-strengthened composite structure cam for circular weft knitting machine.

[0033] The forming method of the partition-strengthened composite structure cam for circular weft knitting machine as described above, in step (1), the mould cavity is accurately divided into three independent powder cavities, namely, the working surface area, the transition area and the mounting area, by the embedded partition plate.

[0034] The forming method of the partition-strengthened composite structure cam for circular weft knitting machine as described above, in step (2), the density of the cam green body is 85-92% of the theoretical density, and the compressive strength is 150-250 MPa;

[0035] Theoretical density = 1 / Σ (Wi / ρi);

[0036] Wherein, Wi is the mass fraction of the i-th component in the free-cutting steel, ρi is the density of the i-th pure substance, and Σ represents the summation of all components.

[0037] The forming method of the partition-strengthened composite structure cam for the compound needle circular weft knitting machine as described above, in step (4), the heat treatment process is: first heat the sintered blank to 1030 DEG C and keep for 30-60 minutes, then immerse in oil to quench to room temperature, then heat the quenched sintered blank to 520 DEG C, keep for 90-120 minutes and then cool to room temperature, then heat again to 520 DEG C, keep for 90-120 minutes and then cool to room temperature.

[0038] Advantages:

[0039] (1) The present application solves the technical problem that the traditional cam cannot simultaneously consider high wear resistance, high impact resistance and excellent processing performance by accurate partition design of material composition, significantly improves the service life and reliability of the cam, and is especially suitable for high-gauge and high-speed weft-knitting circular machines.

[0040] (2) The present application adopts partition composition design in cam manufacturing, optimizes the material formula according to the functional requirements of different parts, and realizes the best combination of wear resistance, toughness and processing performance (i.e. high hardness and good wear resistance of the working surface; sufficient toughness and impact resistance of the transition zone; easy processing and low cost of the mounting zone).

[0041] (3) The present application adopts partition powder metallurgy process to realize the integrated forming of complex composition structure, avoiding the bonding strength problem caused by secondary processing such as welding and inlaying.

[0042] (4) The present application uses high-alloy materials only in the working surface, reducing the consumption of precious elements; near-net forming reduces material waste; excellent processing performance improves production efficiency, and the comprehensive cost is reduced by more than 30%.

[0043] (5) Due to the stress buffering effect of the gradient transition zone, the vibration and noise of the partition-strengthened composite structure cam for the compound needle circular weft knitting machine are reduced under high-speed operation (needle speed 30-40 m / s), the dynamic balance level reaches G2.5 level, the radial runout amount is less than 0.015 mm, ensuring the stable operation of high-gauge needles. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a schematic diagram of the partition-strengthened composite structure cam for the compound needle circular weft knitting machine of the present application;

[0045] Figure 2 is a schematic diagram of the partition-strengthened composite structure cam for the compound needle circular weft knitting machine of the present application at different angles; Figure 1

[0046] In the figure, 1 is the working surface area, 2 is the toughness transition zone, and 3 is the mounting base area. DETAILED DESCRIPTION

[0047] ​The application will be further described below with reference to the specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content of the application, and these equivalent forms also fall within the scope defined by the appended claims.

[0048] In order to ensure the performance of the substances used in each embodiment and comparative example, the manufacturer and brand of the substance are specified, and other products of the manufacturer and brand defined in the application are also feasible.

[0049] The test methods of the relevant performance indicators in each of the following embodiments and comparative examples are as follows:

[0050] Surface roughness: the composite needle circular weft knitting machine with the partition-strengthened composite structure triangle prepared in each embodiment is used as a sample, then a contact type surface roughness measuring instrument (model MarSurf M 300 C, Germany Mar, equipped with a diamond stylus with a needle radius of 2 μm and a cone angle of 90°) is used to test the surface roughness of 5 samples prepared in the same embodiment according to the standard GB / T 1031-2009 “Product Geometric Technical Specification (GPS) Surface Structure Profile Method Surface Roughness Parameter and Its Numerical Value”, and the average value is finally obtained, Ra unit is μm; wherein the length (lr) of each sample is 0.8 mm, and the test is measured at 5 different positions uniformly distributed on each working surface track during the test, and the arithmetic mean value is taken as the final result.

[0051] Hardness: the composite needle circular weft knitting machine with the partition-strengthened composite structure triangle prepared in each embodiment is used as a sample, then the hardness of the working surface area, the toughness transition area and the installation base area of the sample is tested respectively according to the standard GB / T 230.1-2018 “Metallic Materials Rockwell Hardness Test Part 1: Test Method”, and the result is directly read on the Rockwell hardness tester according to the depth difference; wherein the initial test force is 98.07 N, the main test force is 1471 N, the indenter type is diamond cone indenter (apex angle 120°), and the environmental temperature is 20℃.

[0052] Impact toughness: the same raw material formula of the composite needle tricot machine with partitioned reinforced composite structure triangle of each example is used to prepare the corresponding independent standard sample (55 mm x 10 mm x 10 mm) of the working surface area, the toughness transition area and the mounting matrix area respectively, and then the working surface area and the toughness transition area of each sample are tested for impact toughness (i.e. impact energy absorption) according to GB / T 229-2020 "Metallic materials Charpy impact test" standard, i.e. the energy absorbed by the sample when it breaks is measured by a pendulum hitting the standard notched sample once; wherein the sample notch type is a standard V-shaped notch (depth 2 mm), the test temperature is 25℃, the impact instantaneous speed of the pendulum is 5.3 m / s, and the pendulum blade edge curvature radius is 8 mm.

[0053] Wear resistance: the composite needle tricot machine with partitioned reinforced composite structure triangle prepared in each example is used as a sample, and then the wear resistance of the sample is tested according to GB / T 12444-2006 "Metallic materials Wear testing method Ring-block sliding wear test", which is to measure the wear scar width in the middle and both ends of the wear scar (1 mm from the edge), take the average of three measurements, and calculate the volume wear (unit: mm 3 ) according to the average value, i.e. the wear resistance of the sample; wherein the sample size is 12.32 mm (width) x 19.05 mm (length), and the environmental temperature is 25℃.

[0054] Impact fatigue life: the composite needle tricot machine with partitioned reinforced composite structure triangle prepared in each example is used as a sample, and then the impact fatigue life of the sample is tested by a multiple impact tester (model DC-150), until a macroscopic crack with a length of more than 1 mm appears on the sample, and the impact cycle number of the sample from the start to the failure is recorded, i.e. the impact fatigue life; wherein the impact energy is 5 J, the impact frequency is 2 Hz,

[0055] Dynamic balance grade: the composite needle tricot machine with partitioned reinforced composite structure triangle prepared in each example is used as a sample, and then the dynamic balance grade of the sample is tested by a single-sided vertical balancing machine (model YYW-300, balance accuracy grade G6.3) according to GB / T 9239.11-2025 "Mechanical vibration Balancing of rotors Part 11: Balancing methods and tolerances for rigid rotors" standard; wherein the test speed is 80% of the rated speed.

[0056] Radial runout amount: the composite needle circular weft knitting machine with the partitioned reinforced composite structure cam prepared in each example is respectively taken as a sample, the sample is reliably installed on the mandrel, the position of the indicator of the measuring frame (model MarStand 818 series) is adjusted, the measuring head is perpendicular and contacts the working surface area (i.e. the needle tracing curve) of the sample, then the mandrel is slowly and uniformly rotated for one revolution, at the same time, the maximum value and the minimum value of the indicator are recorded, and the radial runout amount of the sample is calculated (i.e. radial runout amount = maximum reading of the indicator - minimum reading of the indicator), at the same time, the radial runout amount of the sample obtained is compared with the linear profile tolerance of 0.05 mm of the needle tracing curve of the cam relative to the positioning reference in the standard FZ / T97010-2016 “General technical conditions for cams of circular weft knitting machines”, if the radial runout amount of the sample is less than the tolerance, it can also be determined that the composite needle circular weft knitting machine with the partitioned reinforced composite structure cam of the application is qualified; wherein the measurement reference is to take the positioning reference surface (i.e. the positioning pin hole) of the cam as the measurement reference.

[0057] Mechanical processing efficiency: the composite needle circular weft knitting machine with the partitioned reinforced composite structure cam prepared in each example is respectively taken as a sample, then the sample is weighed using a precision balance (precision 0.1 g, model Sartorius Quintix35-1S), then the sample is cut using a numerical control machining center (model Haas VF-2 series), after cutting, the cut sample is weighed again using a precision balance, then the cutting volume is obtained according to the weight of the sample before and after cutting (i.e. mass difference / material density), finally the material removal rate (MRR, unit: cm³ / min) is used to quantitatively evaluate the mechanical processing efficiency, and the material removal rate calculation formula is: material removal rate = cutting volume / effective cutting time; wherein the cutter is a 3-blade hard alloy milling cutter with a diameter Φ of 10 mm, the cutting speed (Vc) is 80 m / min, the feed per tooth (fz) is 0.1 mm / tooth, the axial cutting depth (ap) is 2 mm, the radial cutting depth (ae) is 10 mm (full blade cutting), and the cooling method is to use water-based emulsion (concentration 8wt%) under the condition of pressure 0.5 MPa and flow rate 50 L / min.

[0058] Example 1

[0059] A composite needle circular weft knitting machine with a partitioned reinforced composite structure cam, as shown in Figure 1 、 Figure 2 , comprising a working surface area 1, a ductile transition area 2 and a mounting base area 3.

[0060] The working face area 1 adopts high-carbon high-chromium free-cutting steel, and the chemical composition of the high-carbon high-chromium free-cutting steel is as follows in terms of mass percentage: C: 0.95%, Cr: 6%, Mo: 1%, V: 0.3%, Mn: 0.6%, Si: 0.5%, S: 0.1%, and the balance of Fe and inevitable impurities;

[0061] The toughness transition area 2 adopts medium-carbon medium-chromium free-cutting steel, and the chemical composition of the medium-carbon medium-chromium free-cutting steel is as follows in terms of mass percentage: C: 0.5%, Cr: 3%, Mo: 0.5%, Mn: 0.6%, Si: 0.2%, S: 0.06%, and the balance of Fe and inevitable impurities;

[0062] The mounting base area 3 adopts low-carbon low-chromium free-cutting steel, and the chemical composition of the low-carbon low-chromium free-cutting steel is as follows in terms of mass percentage: C: 0.2%, Cr: 1%, Mn: 0.9%, S: 0.24%, Ca: 0.002%, and the balance of Fe and inevitable impurities;

[0063] The working face area 1, the toughness transition area 2 and the mounting base area 3 are obtained by integrated forming;

[0064] From the interface on both sides of the working face area 1 to the toughness transition area 2, along a 50-micron-wide transition zone, the C content gradually decreases from 0.95% to 0.45%, the Cr content gradually decreases from 5.5% to 2.5%, and the Mo content gradually decreases from 0.8% to 0.4%;

[0065] From the interface on both sides of the toughness transition area 2 to the mounting base area 3, along a 50-micron-wide transition zone, the C content gradually decreases from 0.45% to 0.15%, and the Cr content gradually decreases from 2.5% to 0.8%.

[0066] The forming method of the partition-strengthened composite structure cam of the circular weft knitting machine as described above is as follows:

[0067] (1) Mould design and powder filling: according to the three-dimensional model of the cam, a precision mould is designed, and the mould cavity is partitioned into the working face area, the toughness transition area and the mounting base area in sequence by embedded partition plates according to functions, and the free-cutting steel powder of corresponding composition is accurately filled into each powder cavity;

[0068] (2) Cold isostatic pressing forming: two-way pressing is carried out under a pressure of 300 MPa to obtain a cam green body;

[0069] The compressive strength of the obtained cam green body is 150 MPa, and the theoretical density is 7.5 g / cm 3, the density is 85% of the theoretical density; wherein, the calculation formula of the theoretical density is: theoretical density = 1 / Σ (Wi / ρi), wherein, Wi is the mass fraction of the i-th component in the free-cutting steel, and ρi is the density of the pure substance of the i-th component;

[0070] (3) High-temperature vacuum sintering: the triangular green body is placed in a vacuum sintering furnace with a vacuum degree of 1.0 x 10 -1 Pa and a temperature of 1250 DEG C for 90 minutes, to obtain a sintered body;

[0071] (4) Heat treatment and finishing: the sintered body is first heated to 1030 DEG C and kept for 30 minutes, then immersed in oil for quenching to 20 DEG C, then the quenched sintered body is heated to 520 DEG C, kept for 90 minutes and cooled to 20 DEG C, then heated to 520 DEG C again, kept for 90 minutes and cooled to 20 DEG C, then the working track of the working surface of the cooled sintered body is ground and polished to make the surface roughness Ra 0.1 μm, to obtain the composite needle tricot machine partition-strengthened composite structure triangular.

[0072] The hardness HRC of the working surface area of the finally prepared composite needle tricot machine partition-strengthened composite structure triangular is 62, the hardness HRC of the toughness transition area is 52, the hardness HRC of the mounting base area is 28, the impact toughness of the working surface area is 8 J, and the impact toughness of the toughness transition area is 25 J;

[0073] The wear resistance of the composite needle tricot machine partition-strengthened composite structure triangular is 0.3 mm 3 , the impact fatigue life is 75000 times, the dynamic balance grade is G2.5 grade, and the machining efficiency is 11 cm 3 / min; the radial runout of the working surface area of the composite needle tricot machine partition-strengthened composite structure triangular is 0.005 mm.

[0074] The composite needle tricot machine partition-strengthened composite structure triangular obtained above can be used for the composite triangular of a 46-inch diameter, E44 high-speed single-face weft-knitting large circular machine.

[0075] Example 2

[0076] A composite needle tricot machine partition-strengthened composite structure triangular, comprising a working surface area, a toughness transition area and a mounting base area;

[0077] The working surface area is made of high-carbon high-chromium free-cutting steel, and the chemical composition of the high-carbon high-chromium free-cutting steel is as follows in terms of mass percentage: C: 1%, Cr: 5.5%, Mo: 0.8%, V: 0.2%, Mn: 0.55%, Si: 0.55%, S: 0.12%, and the balance is Fe and unavoidable impurities;

[0078] The toughness transition zone adopts a medium-carbon medium-chromium free-cutting steel, and the chemical composition of the medium-carbon medium-chromium free-cutting steel is as follows in terms of mass percentage: C: 0.45%, Cr: 2.5%, Mo: 0.4%, Mn: 0.75%, Si: 0.3%, S: 0.075%, and the balance of Fe and inevitable impurities;

[0079] The installation base zone adopts a low-carbon low-chromium free-cutting steel, and the chemical composition of the low-carbon low-chromium free-cutting steel is as follows in terms of mass percentage: C: 0.15%, Cr: 0.8%, Mn: 1.05%, S: 0.28%, Ca: 0.004%, and the balance of Fe and inevitable impurities;

[0080] The working face zone, the toughness transition zone and the installation base zone are obtained through integrated forming;

[0081] From the interface on both sides of the working face zone to the toughness transition zone, along a 125-micron-wide transition zone, the C content gradually decreases from 1.025% to 0.5%, the Cr content gradually decreases from 6% to 3%, and the Mo content gradually decreases from 1% to 0.5%;

[0082] From the interface on both sides of the toughness transition zone to the installation base zone, along a 125-micron-wide transition zone, the C content gradually decreases from 0.5% to 0.2%, and the Cr content gradually decreases from 3% to 1%.

[0083] The forming method of the partition-strengthened composite structure cam for the compound needle circular weft knitting machine as described above is as follows:

[0084] (1) Mould design and powder filling: a precision mould is designed according to the three-dimensional model of the cam, the mould cavity is partitioned into the working face zone, the toughness transition zone and the installation base zone through embedded partition plates in sequence, and the free-cutting steel powder of corresponding composition is accurately filled into each powder cavity;

[0085] (2) Cold isostatic pressing forming: two-way pressing is performed under a pressure of 400 MPa to obtain a cam green body;

[0086] The compressive strength of the obtained cam green body is 200 MPa, the theoretical density is 7.75 g / cm 3 , and the density is 88.5% of the theoretical density; wherein, the calculation formula of the theoretical density is: theoretical density = 1 / Σ (Wi / ρi), wherein, Wi is the mass fraction of the i-th component in the free-cutting steel, and ρi is the density of the pure i-th component;

[0087] (3) High-temperature vacuum sintering: the cam green body is placed in a vacuum sintering furnace with a vacuum degree of 5.0×10 -2 Pa and a temperature of 1260℃, and is kept for 100 minutes to obtain a sintered body;

[0088] (4) Heat treatment and finishing: First, heat the sintered blank to 1030℃ and hold for 50 minutes, then immerse it in oil and quench it to 22.5℃. Then heat the quenched sintered blank to 520℃, hold for 105 minutes and cool it to 22.5℃. Then heat it to 520℃ again, hold for 105 minutes and cool it to 22.5℃. Then grind and polish the working track of the working surface of the cooled sintered blank to make the surface roughness Ra 0.15μm, thus obtaining the triangular composite structure with partition reinforcement for the composite needle circular weft machine.

[0089] The final composite needle circular weft machine has a working surface area hardness of HRC 63, a toughness transition area hardness of HRC 53, a mounting base area hardness of HRC 30, an impact toughness of 9J in the working surface area, and an impact toughness of 26J in the toughness transition area.

[0090] The wear resistance of the triangular composite structure with partitioned reinforcement used in composite needle circular knitting machines is 0.4mm. 3 It has an impact fatigue life of 97,500 cycles, a dynamic balance grade of G3.7, and a machining efficiency of 14 cm. 3 / min; The radial runout of the working surface area of ​​the triangular composite structure of the composite needle circular weft machine is 0.01mm.

[0091] The composite needle circular knitting machine with partitioned reinforced composite structure triangle obtained above can be used in composite triangles for high-speed single-sided circular knitting machines with a cylinder diameter of 46 inches and a machine size of E44.

[0092] Example 3

[0093] A triangular composite structure with partitioned reinforcement for a composite needle circular weft knitting machine includes a working surface area, a toughness transition area, and an installation base area;

[0094] The working surface area is made of high-carbon, high-chromium free-cutting steel. The chemical composition of the high-carbon, high-chromium free-cutting steel by mass percentage is: C: 1.1%, Cr: 6.5%, Mo: 1.2%, V: 0.4%, Mn: 0.5%, Si: 0.6%, S: 0.14%, with the balance being Fe and unavoidable impurities.

[0095] The toughness transition zone uses medium-carbon, medium-chromium free-cutting steel. The chemical composition of the medium-carbon, medium-chromium free-cutting steel, by mass percentage, is: C: 0.55%, Cr: 3.5%, Mo: 0.6%, Mn: 0.9%, Si: 0.4%, S: 0.09%, with the balance being Fe and unavoidable impurities.

[0096] The installation base area adopts low-carbon and low-chromium free-cutting steel, and the chemical composition of the low-carbon and low-chromium free-cutting steel is as follows in percentage by mass: C: 0.25%, Cr: 1.2%, Mn: 1.2%, S: 0.25%, Ca: 0.006%, and the balance of Fe and inevitable impurities;

[0097] The working surface area, the toughness transition area and the installation base area are obtained by integrated forming;

[0098] From the interface between the working surface area and the toughness transition area to both sides, along a 200-micron-wide transition zone, the C content gradually decreases from 1.1% to 0.55%, the Cr content gradually decreases from 6.5% to 3.5%, and the Mo content gradually decreases from 1.2% to 0.6%;

[0099] From the interface between the toughness transition area and the installation base area to both sides, along a 200-micron-wide transition zone, the C content gradually decreases from 0.55% to 0.25%, and the Cr content gradually decreases from 3.5% to 1.2%.

[0100] The forming method of the partition-strengthened composite structure cam for the compound needle circular weft knitting machine as described above is as follows:

[0101] (1) Mould design and powder filling: according to the three-dimensional model of the cam, a precision mould is designed, and the mould cavity is partitioned into the working surface area, the toughness transition area and the installation base area by embedded partitions in sequence, and the free-cutting steel powder of corresponding composition is accurately filled into each powder cavity;

[0102] (2) Cold isostatic pressing forming: two-way pressing is performed under a pressure of 600 MPa to obtain a cam green body;

[0103] The compressive strength of the obtained cam green body is 250 MPa, the theoretical density is 8 g / cm 3 , and the density is 92% of the theoretical density; wherein, the calculation formula of the theoretical density is: theoretical density = 1 / Σ (Wi / ρi), wherein, Wi is the mass fraction of the i-th component in the free-cutting steel, and ρi is the density of the pure substance of the i-th component;

[0104] (3) High-temperature vacuum sintering: the cam green body is placed in a vacuum sintering furnace with a vacuum degree of 1.0×10 -3 Pa and a temperature of 1280℃, and is kept for 110 minutes to obtain a sintered body;

[0105] (4) heat treatment and finishing: first heat the sintered blank to 1030 DEG C and keep for 60 minutes, then immerse in oil to quench to 25 DEG C, then heat the quenched sintered blank to 520 DEG C, keep for 120 minutes and cool to 25 DEG C, then heat again to 520 DEG C, keep for 120 minutes and cool to 25 DEG C, then grind and polish the working track of the working face of the cooled sintered blank, so that the surface roughness Ra is 0.2 μm, thus the partition-strengthened composite structure cam for circular weft knitting machine is obtained.

[0106] The hardness HRC of the working face area of the finally prepared partition-strengthened composite structure cam for circular weft knitting machine is 64, the hardness HRC of the toughness transition area is 54, the hardness HRC of the mounting base area is 32, the impact toughness of the working face area is 10 J, and the impact toughness of the toughness transition area is 27 J;

[0107] The wear resistance of the partition-strengthened composite structure cam for circular weft knitting machine is 0.5 mm 3 , the impact fatigue life is 120000 times, the dynamic balance grade is G5.0 grade, and the machining efficiency is 17 cm 3 / min; the radial runout of the working face area of the partition-strengthened composite structure cam for circular weft knitting machine is 0.015 mm.

[0108] The partition-strengthened composite structure cam for circular weft knitting machine obtained above can be used for the composite cam of a high-speed single-face weft-knitting large circular machine with a cylinder diameter of 46 inches and a machine gauge of E44.

[0109] Example 4

[0110] A partition-strengthened composite structure cam for circular weft knitting machine, comprising a working face area, a toughness transition area and a mounting base area;

[0111] The working face area is made of high-carbon high-chromium free-cutting steel, and the chemical composition of the high-carbon high-chromium free-cutting steel is as follows in terms of mass percentage: C: 1.05%, Cr: 5.8%, Mo: 1.1%, V: 0.25%, Mn: 0.58%, Si: 0.52%, S: 0.11%, and the balance of Fe and inevitable impurities;

[0112] The toughness transition area is made of medium-carbon medium-chromium free-cutting steel, and the chemical composition of the medium-carbon medium-chromium free-cutting steel is as follows in terms of mass percentage: C: 0.52%, Cr: 2.8%, Mo: 0.55%, Mn: 0.8%, Si: 0.25%, S: 0.07%, and the balance of Fe and inevitable impurities;

[0113] The mounting base area adopts low-carbon and low-chromium free-cutting steel, and the chemical composition of the low-carbon and low-chromium free-cutting steel is as follows in percentage by mass: C: 0.23%, Cr: 0.9%, Mn: 1%, S: 0.26%, Ca: 0.003%, and the balance of Fe and inevitable impurities;

[0114] The working surface area, the toughness transition area and the mounting base area are obtained by integrated forming;

[0115] From the interface between the working surface area and the toughness transition area to both sides, along a transition zone of 80 microns wide, the C content gradually decreases from 1.05% to 0.48%, the Cr content gradually decreases from 5.8% to 2.8%, and the Mo content gradually decreases from 0.9% to 0.45%;

[0116] From the interface between the toughness transition area and the mounting base area to both sides, along a transition zone of 150 microns wide, the C content gradually decreases from 0.51% to 0.18%, and the Cr content gradually decreases from 2.75% to 0.9%.

[0117] The forming method of the partition-strengthened composite structure cam for the compound needle circular weft knitting machine as described above is as follows:

[0118] (1) Mould design and powder filling: according to the three-dimensional model of the cam, a precision mould is designed, and the mould cavity is partitioned into the working surface area, the toughness transition area and the mounting base area three independent powder cavities in sequence through embedded partition plates according to functions, and the free-cutting steel powder of corresponding composition is accurately filled into each powder cavity;

[0119] (2) Cold isostatic pressing forming: two-way pressing is carried out under a pressure of 500 MPa to obtain a cam green body;

[0120] The compressive strength of the obtained cam green body is 175 MPa, the theoretical density is 7.6 g / cm 3 , and the density is 87% of the theoretical density; wherein, the calculation formula of the theoretical density is: theoretical density = 1 / Σ (Wi / ρi), wherein, Wi is the mass fraction of the i-th component in the free-cutting steel, and ρi is the density of the pure substance of the i-th component;

[0121] (3) High-temperature vacuum sintering: the cam green body is placed in a vacuum sintering furnace with a vacuum degree of 7.5×10 -2 Pa and a temperature of 1270℃, and is kept for 120 minutes to obtain a sintered body;

[0122] (4) heat treatment and finishing: first heat the sintered blank to 1030 DEG C and keep for 40 minutes, then immerse in oil to quench to 23 DEG C, then heat the quenched sintered blank to 520 DEG C, keep for 100 minutes and cool to 23 DEG C, then heat to 520 DEG C again, keep for 98 minutes and cool to 23 DEG C, then grind and polish the working track of the working face of the cooled sintered blank, so that the surface roughness Ra is 0.16 μm, thus a partition-strengthened composite structure cam for a compound needle circular weft knitting machine is obtained.

[0123] The hardness HRC of the working face area of the finally prepared partition-strengthened composite structure cam for a compound needle circular weft knitting machine is 62.5, the hardness HRC of the toughness transition area is 53.5, the hardness HRC of the mounting base area is 31, the impact toughness of the working face area is 9 J, and the impact toughness of the toughness transition area is 26 J;

[0124] The wear resistance of the partition-strengthened composite structure cam for a compound needle circular weft knitting machine is 0.35 mm 3 , the impact fatigue life is 85000 times, the dynamic balance grade is G3, the radial runout amount is 0.008 mm, and the machining efficiency is 13 cm 3 / min; the radial runout amount of the working face area of the partition-strengthened composite structure cam for a compound needle circular weft knitting machine is 0.008 mm.

[0125] The partition-strengthened composite structure cam for a compound needle circular weft knitting machine obtained above can be used for a compound cam of a 46-inch diameter, E44 high-speed single-face weft-knitting large circular machine.

[0126] Example 5

[0127] A partition-strengthened composite structure cam for a compound needle circular weft knitting machine, comprising a working face area, a toughness transition area and a mounting base area;

[0128] The working face area is made of high-carbon high-chromium free-cutting steel, and the chemical composition of the high-carbon high-chromium free-cutting steel is as follows in terms of mass percentage: C: 0.98%, Cr: 6.2%, Mo: 0.9%, V: 0.32%, Mn: 0.6%, Si: 0.58%, S: 0.13%, and the balance is Fe and unavoidable impurities;

[0129] The toughness transition area is made of medium-carbon medium-chromium free-cutting steel, and the chemical composition of the medium-carbon medium-chromium free-cutting steel is as follows in terms of mass percentage: C: 0.47%, Cr: 3.2%, Mo: 0.46%, Mn: 0.7%, Si: 0.35%, S: 0.08%, and the balance is Fe and unavoidable impurities;

[0130] The installation base area adopts low-carbon and low-chromium free-cutting steel, and the chemical composition of the low-carbon and low-chromium free-cutting steel is as follows in percentage by mass: C: 0.18%, Cr: 1.1%, Mn: 1.1%, S: 0.27%, Ca: 0.005%, and the balance of Fe and inevitable impurities;

[0131] The working surface area, the toughness transition area and the installation base area are obtained by integrated forming;

[0132] From the interface between the working surface area and the toughness transition area to both sides, along a 150-micron-wide transition zone, the C content gradually decreases from 1% to 0.53%, the Cr content gradually decreases from 6.3% to 3.2%, and the Mo content gradually decreases from 1.1% to 0.55%;

[0133] From the interface between the toughness transition area and the installation base area to both sides, along a 75-micron-wide transition zone, the C content gradually decreases from 0.47% to 0.22%, and the Cr content gradually decreases from 3.25% to 1.1%.

[0134] The forming method of the partition-strengthened composite structure cam for the compound needle circular weft knitting machine as described above is as follows:

[0135] (1) Mould design and powder filling: according to the three-dimensional model of the cam, a precision mould is designed, and the mould cavity is partitioned into the working surface area, the toughness transition area and the installation base area three independent powder cavities in sequence through embedded partition plates according to functions, and the free-cutting steel powder of corresponding composition is accurately filled into each powder cavity;

[0136] (2) Cold isostatic pressing forming: two-way pressing is carried out under a pressure of 450 MPa to obtain a cam green body;

[0137] The compressive strength of the obtained cam green body is 225 MPa, the theoretical density is 7.9 g / cm 3 , and the density is 91% of the theoretical density; wherein, the calculation formula of the theoretical density is: theoretical density = 1 / Σ (Wi / ρi), wherein, Wi is the mass fraction of the i-th component in the free-cutting steel, and ρi is the density of the pure substance of the i-th component;

[0138] (3) High-temperature vacuum sintering: the cam green body is placed in a vacuum sintering furnace with a vacuum degree of 2.5×10 -2 Pa and a temperature of 1265℃, and is kept for 105 minutes to obtain a sintered body;

[0139] (4) heat treatment and finishing: first heat the sintered blank to 1030℃ and keep for 45 minutes, then immerse in oil to quench to 24℃, then heat the quenched sintered blank to 520℃, keep for 110 minutes and cool to 24℃, then heat again to 520℃, keep for 112 minutes and cool to 24℃, then grind and polish the working track of the working surface of the cooled sintered blank, so that the surface roughness Ra is 0.18μm, thus the partition-strengthened composite structure cam for circular weft knitting machine is obtained.

[0140] The hardness HRC of the working surface area of the finally prepared partition-strengthened composite structure cam for circular weft knitting machine is 63.5, the hardness HRC of the toughness transition area is 54.6, the hardness HRC of the mounting base area is 29, the impact toughness of the working surface area is 10J, and the impact toughness of the toughness transition area is 27J.

[0141] The wear resistance of the partition-strengthened composite structure cam for circular weft knitting machine is 0.45mm 3 , the impact fatigue life is 105000 times, the dynamic balance grade is G4, the machining efficiency is 16cm 3 / min, and the radial runout of the working surface area of the partition-strengthened composite structure cam for circular weft knitting machine is 0.012mm.

[0142] The partition-strengthened composite structure cam for circular weft knitting machine obtained above can be used as a composite cam for a 46-inch E44 high-speed single-face weft-knitting circular machine.

Claims

1. A triangular composite structure with partitioned reinforcement for a composite needle circular weft knitting machine, characterized in that: This includes the working surface area, the toughness transition area, and the mounting substrate area; The working surface area uses high-carbon, high-chromium free-cutting steel, the toughness transition area uses medium-carbon, medium-chromium free-cutting steel, and the mounting base area uses low-carbon, low-chromium free-cutting steel. The chemical composition of high-carbon, high-chromium free-cutting steel includes Mo and S elements; the chemical composition of medium-carbon, medium-chromium free-cutting steel includes Mo element; and the chemical composition of low-carbon, low-chromium free-cutting steel includes Ca and S elements. The working surface area, the toughness transition area, and the mounting base area are obtained through integrated molding; Along a transition zone 50–200 micrometers wide, from the interface between the working surface and the tough transition zone, the C content gradually decreases from 0.95–1.10% to 0.45–0.55%, the Cr content gradually decreases from 5.5–6.5% to 2.5–3.5%, and the Mo content gradually decreases from 0.8–1.2% to 0.4–0.6%. Along the interface between the tough transition zone and the mounting substrate zone, along a transition zone 50-200 micrometers wide, the C content gradually decreases from 0.45-0.55% to 0.15-0.25%, and the Cr content gradually decreases from 2.5-3.5% to 0.8-1.2%.

2. The triangular composite structure for a composite needle circular knitting machine with partitioned reinforcement according to claim 1, characterized in that, The chemical composition of high-carbon, high-chromium free-cutting steel, by mass percentage, is as follows: C: 0.95~1.10%, Cr: 5.5~6.5%, Mo: 0.8~1.2%, V: 0.2~0.4%, Mn: ≤0.6%, Si: ≤0.6%, S: 0.10~0.14%, with the balance being Fe and unavoidable impurities.

3. The triangular composite structure with partitioned reinforcement for a composite needle circular weft knitting machine according to claim 2, characterized in that, The chemical composition of medium carbon and medium chromium free-cutting steel, by mass percentage, is as follows: C: 0.45~0.55%, Cr: 2.5~3.5%, Mo: 0.4~0.6%, Mn: 0.6~0.9%, Si: 0.2~0.4%, S: 0.06~0.09%, with the balance being Fe and unavoidable impurities.

4. The triangular composite structure for a composite needle circular weft knitting machine with partitioned reinforcement according to claim 3, characterized in that, The chemical composition of low-carbon, low-chromium free-cutting steel, by mass percentage, is as follows: C: 0.15~0.25%, Cr: 0.8~1.2%, Mn: 0.9~1.2%, S: 0.24~0.28%, Ca: 0.002~0.006%, with the balance being Fe and unavoidable impurities.

5. A method for forming a triangular composite structure with partitioned reinforcement for a composite needle circular knitting machine as described in any one of claims 1 to 4, characterized in that: First, a precision mold is designed based on the three-dimensional model of the triangle. The mold cavity is divided into three independent powder cavities according to the functional partitions: the working surface area, the toughness transition area, and the mounting base area. Each powder cavity is precisely filled with free-cutting steel powder of the corresponding composition. Then, it is subjected to cold isostatic pressing, high-temperature vacuum sintering, heat treatment, and precision machining to obtain the triangular partitioned reinforced composite structure for composite needle circular knitting machines. The temperature for high-temperature vacuum sintering is above 1250℃.

6. The method for forming a triangular composite structure with partitioned reinforcement for a composite needle circular weft knitting machine according to claim 5, characterized in that, The specific steps are as follows: (1) Mold design and powder filling: Based on the three-dimensional model of the triangle, a precision mold is designed. The mold cavity is divided into three independent powder cavities in sequence according to the functional area: the working surface area, the toughness transition area and the mounting base area. Each powder cavity is precisely filled with free-cutting steel powder of the corresponding composition. (2) Cold isostatic pressing: bidirectional pressing is performed under a pressure of 300~600 MPa to obtain a triangular green blank; (3) High-temperature vacuum sintering: Place the triangular green billet in a vacuum sintering furnace at 1250~1280℃ and hold for 90~120 minutes to obtain the sintered billet; (4) Heat treatment and finishing: First, heat treatment is performed on the sintered blank, and then the working track of the working surface of the heat-treated sintered blank is ground and polished to make the surface roughness Ra ≤ 0.2 μm, thus obtaining the triangular parted reinforced composite structure for composite needle circular weft machine.

7. The method for forming a triangular composite structure with partitioned reinforcement for a composite needle circular weft knitting machine according to claim 6, characterized in that, In step (1), the mold cavity is precisely divided into three independent powder cavities: the working surface area, the transition area, and the installation area, by an embedded partition.

8. The method for forming a triangular composite structure with partitioned reinforcement for a composite needle circular weft knitting machine according to claim 6, characterized in that, In step (2), the density of the triangular green body is 85-92% of the theoretical density, and the compressive strength is 150-250 MPa; Theoretical density = 1 / Σ (Wi / ρi); Where Wi is the mass fraction of the i-th component in the free-cutting steel, and ρi is the density of the i-th component as a pure substance.

9. The method for forming a triangular composite structure with partitioned reinforcement for a composite needle circular weft knitting machine according to claim 6, characterized in that, In step (4), the heat treatment process is as follows: first, heat the sintered billet to 1030℃ and hold it for 30~60 minutes, then immerse it in oil and quench it to room temperature, then heat the quenched sintered billet to 520℃, hold it for 90~120 minutes and then cool it to room temperature, then heat it again to 520℃, hold it for 90~120 minutes and then cool it to room temperature.

Images