Laser hardening method and related components for improving local wear resistance of circular knitting machines

Abstract

This invention provides a laser quenching method and related components for improving the local wear resistance of circular knitting machines. The laser quenching method includes the following steps: S1, inspecting the appearance and dimensions of the part to be quenched, performing material analysis to determine matching process parameters, and performing preliminary heat treatment on the part; pre-treating the surface of the part; S2, clamping the part to be quenched, planning the laser scanning path, and preset the laser process parameters; S3, scanning the area to be quenched with the laser beam along the preset path to reach the target temperature, and then rapidly cooling after removing the laser beam to complete the quenching. This method can achieve the required hardness of the parts with minimal deformation, overcoming various drawbacks of traditional heat treatment processes.

Description

Technical Field

[0001] This invention relates to the field of textile circular knitting machine technology, specifically to a laser quenching method and related components for improving the local wear resistance of circular knitting machines. Background Technology

[0002] In the textile industry, circular knitting machines primarily work by evenly arranging needles and blades on the surface of a circular housing (commonly known as a needle cylinder). Through a specific cam structure, the needles and blades form a specific motion curve, causing the fed yarn to form interlocking loops, ultimately forming the fabric surface. Therefore, the movement between the needles / blades and the needle cylinder is through direct contact and friction. The industry practice is to make the stiffness of the needles / blades lower than the stiffness of certain areas of the needle cylinder, and to treat them as consumable parts.

[0003] Laser hardening, also known as laser phase transformation hardening, falls under the category of surface heat treatment. It involves irradiating the workpiece surface with a high-energy-density laser beam, rapidly heating it to above the phase transformation temperature but below the melting point to form austenite. The heat is then quickly transferred to the matrix for rapid cooling, resulting in a highly hardened layer with extremely fine martensite and other structural features. Based on the solid-state phase transformation recrystallization strengthening mechanism, laser-hardened layers exhibit superior hardness, wear resistance, and ductility compared to traditionally hardened layers. Furthermore, laser hardening offers excellent controllability in the shape, size, and location of the hardened area, as well as the depth of the hardened layer.

[0004] Laser hardening technology stands out in multiple fields due to its unique advantages. It boasts rapid heating and cooling speeds, short process cycles, and eliminates the need for external quenching media, making it highly efficient and environmentally friendly. Its instantaneous localized heating characteristic results in minimal workpiece deformation while ensuring a clean working environment. Furthermore, the processed workpiece requires no further finishing and its size is not limited by heat treatment equipment. Notably, laser hardening achieves a hardness 5-20% higher than conventional hardening processes, with controllable hardening depth, allowing for large-area laser heat treatment. Its heat-affected zone is only about 0.3-1.0 mm, with minimal deformation and a tight bond between the hardened layer and the substrate. During laser heat treatment, the distance between the processing head and the workpiece surface can reach 100-300 mm, making the process convenient and flexible. More importantly, the integration of laser hardening technology with robotic equipment makes the production process more efficient and significantly reduces labor costs.

[0005] In a circular knitting machine, the needles reciprocate up and down in the cylinder. Due to the horizontal radial tension of the fabric, sliding friction occurs between the outer end of the cylinder nozzle and the back of the needle. Similarly, the Schenker sheet reciprocates horizontally in the groove of the Schenker ring, and the vertical tension of the fabric causes sliding friction between the bottom surface of the Schenker sheet and the bottom of the Schenker groove. These frictions can cause indentations due to factors such as the surface hardness of the parts, the age of the machine, lubrication effectiveness, fabric tension, and machine maintenance frequency, ultimately leading to defects such as vertical streaks and dark lines on the fabric surface.

[0006] In traditional industries, solutions for syringe heat treatment technology are generally categorized as follows: Technical Solution 1: Carburizing and quenching are used to achieve the designed hardness, wear resistance, and other properties. A certain amount of carburized layer allowance is left, and deformation is controlled by grinding. Controlled atmosphere heat treatment is used for carburizing. By controlling the furnace temperature, holding time, and carbon potential, a suitable mandrel is selected for quenching heat treatment to ensure the required deformation of the syringe's outer diameter after carburizing and quenching. This solution has high requirements for the workpiece material composition, degree of carburizing, and temperature. Inaccurate control can lead to excessive carbon content and brittle fracture.

[0007] Technical Solution Two: A quenching inductor is used for quenching to ensure that the hardness, effective hardening depth, and deformation after quenching meet the technical requirements of the drawings. Through a structural design scheme for the quenching inductor, a method is provided that avoids melting or cracking caused by high-power inductors, allowing the material layer on the edge of the syringe to be heated to the quenching temperature and depth in one pass, followed by immediate water cooling to achieve the required quenched surface hardness.

[0008] There are two methods for quenching and heating high-frequency syringes: The first method is simultaneous heating and quenching, which involves heating the entire surface of the syringe nozzle that needs to be quenched at the same time, followed by rapid cooling.

[0009] The shortcomings of this method are: (1) different parts require different sensors, resulting in poor processing flexibility; (2) the parts are prone to uneven heating, leading to an excessively deep or shallow hardened layer, which cannot achieve the required hardness and depth.

[0010] The second method is sequential continuous heating and quenching, which involves using induction heating to heat a small portion of the surface of the syringe nozzle while the syringe rotates circumferentially to sequentially heat and cool the surface.

[0011] Comparing the two induction hardening methods, integral hardening will cause the problem of dimensional shrinkage and deformation; although sequential hardening can improve the above drawbacks, it still has the problem of excessive hardening depth, which will cause overall brittleness in thin-walled structures with fine needle pitch.

[0012] Based on the above points, laser hardening is a heat treatment process that can control the amount of deformation, resulting in a hard surface and internal toughness. By controlling the focusing size, power, and relative rotation speed of the laser relative to the cylinder, a uniform hardness layer with a hardness of 58~62HRc can be achieved.

[0013] In view of this, the inventors of this application have designed a laser quenching method and related components to improve the local wear resistance of circular knitting machines, in order to overcome the above-mentioned technical problems. Summary of the Invention

[0014] The technical problem to be solved by this invention is to overcome the shortcomings of existing technologies, such as the easy generation of dents and fabric defects caused by sliding friction of various parts during the operation of circular knitting machines, and the pain points of traditional carburizing and induction hardening processes, which have high parameter control requirements, are prone to brittleness, have poor processing flexibility, uncontrollable hardened layer depth, and are prone to deformation or poor adaptability. There is a lack of heat treatment solutions that can take into account the precise control of the hardened layer, small workpiece deformation, no risk of brittleness, and adaptability to multiple specifications of parts. This invention provides a laser hardening method and related components to improve the local wear resistance of circular knitting machines.

[0015] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides a laser hardening method for improving the local wear resistance of a circular knitting machine. The method comprises the following steps: S1. Inspecting the appearance and dimensions of the part to be hardened, performing material analysis to determine matching process parameters, and performing pre-heat treatment on the part; pre-treating the surface of the part; S2. Clamping the part to be hardened, planning the laser scanning path, and pre-setting the laser process parameters; S3. Scanning the area to be hardened along the preset path with the laser beam until the target temperature is reached, and then rapidly cooling after removing the laser beam to complete the hardening process.

[0016] According to one or more embodiments of the present invention, after step S3, the following steps are further included: S4, performing post-processing on the quenched area, conducting quality inspection and performance verification.

[0017] According to one or more embodiments of the present invention, the component to be quenched includes an outer Sinking ring, a needle plate, and a syringe body structure; the quenching area of ​​the outer Sinking ring is the upper end face of the extension section of the groove bottom structure of the outer Sinking ring; the quenching area of ​​the needle plate is the pre-set circumferential annular band of the needle plate; the quenching area of ​​the syringe body structure is both sides of the top nozzle thin-walled structure of the syringe body structure.

[0018] According to one or more embodiments of the present invention, step S1 includes the following steps: S 111. Confirm that the part to be quenched is free of cracks, porosity, and deformation; measure the dimensions of the area to be quenched; determine the required depth and hardness of the hardened layer; confirm the steel grade of the part to be quenched, assess its hardenability, and formulate matching process parameters; 2. Normalize the part to be quenched; 12 First, wipe the surface of the parts to be quenched to remove oil, grind to remove rust and remove oxide scale, and ensure that the surface is dry and clean. Then, apply a light-absorbing coating to the surface of the parts to be quenched to improve the laser absorption rate. Finally, pass an inert gas through the surface of the parts to be quenched for protection.

[0019] According to one or more embodiments of the present invention, step S2 includes the following steps: S 21 The parts to be quenched are fixed to the CNC worktable using tooling clamps; 22 Plan the scanning path and set the spot overlap rate to ensure a continuous and uniform hardened layer; S 23 1. Pre-set laser process parameters to match the requirements of the material and the hardened layer; laser process parameters include laser power, scanning speed, spot diameter, and defocusing amount.

[0020] According to one or more embodiments of the present invention, step S3 includes the following steps: S 31 The laser beam rapidly heats the surface layer to the austenitizing temperature, and the heating rate must ensure that only the surface layer undergoes a phase transformation, while the substrate temperature remains below the phase transformation temperature; S 32 The laser beam scans at a uniform speed along a preset path, controlling the heat input power and speed to ensure a uniform hardened layer; S 33 Once the laser beam is removed, the high temperature on the surface is cooled through heat conduction to the substrate, transforming austenite into martensite.

[0021] According to one or more embodiments of the present invention, step S 31 In the process, the laser beam has a rectangular spot shape and is focused on the surface of the component. When quenching the upper surface of the disc-shaped component, the laser beam spot is oriented at an angle α with the radius or axial direction of the disc-shaped component. When quenching the outer surface of the cylindrical component, the laser beam spot is oriented at an angle β with the axial direction of the disc-shaped component.

[0022] According to one or more embodiments of the present invention, step S4 includes the following steps: S 41 Remove residual light-absorbing coating and clean the surface; remove internal stress after quenching; perform fine grinding to ensure dimensional accuracy and surface roughness; S 42 1. Detect surface hardness; 2. Microscopically examine the hardened layer structure; 3. Detect surface cracks and ablation, and measure the deformation; 4. Perform wear resistance and fatigue strength tests.

[0023] The present invention also provides an outer Schenker ring for a circular knitting machine, characterized in that the upper part of the outer Schenker ring of the circular knitting machine has a semi-swallowtail-shaped first groove structure, the lower part of the first groove structure is connected to a first groove bottom platform, a first extension section is provided on the inner side of the first groove bottom platform, and the upper end surface of the first extension section is quenched by the laser quenching method described above for improving the local wear resistance of the circular knitting machine.

[0024] The present invention also provides a needle plate for a circular knitting machine, characterized in that the needle plate of the circular knitting machine has a pre-set circumferential annular belt at the mouth, and the pre-set circumferential annular belt is quenched by the laser quenching method described above for improving the local wear resistance of the circular knitting machine.

[0025] The present invention also provides a main body structure for a circular knitting machine, characterized in that a second groove structure is provided on the upper part of the thin-walled structure at the top of the main body structure, the lower part of the second groove structure is connected to a second groove bottom platform, and the inner side of the second groove bottom platform has a trumpet-shaped groove; the outer vertical surface of the thin-walled structure at the top, the vertical surface above the inner trumpet-shaped groove of the thin-walled structure at the top, and the upper surface near the inner side of the second groove bottom platform are quenched using the laser quenching method described above to improve the local wear resistance of the circular knitting machine.

[0026] The present invention also provides a main body structure of a cylinder for a circular knitting machine, characterized in that a second groove structure is provided on the upper part of the thin-walled structure of the nozzle at the top of the main body structure of the cylinder, the bottom surface of the second groove structure is connected to a second groove bottom platform, and a second extension section is provided on the inner side of the second groove bottom platform; the outer vertical surface of the thin-walled structure of the nozzle and the upper surface of the second extension section are quenched by the laser quenching method described above for improving the local wear resistance of the circular knitting machine.

[0027] The present invention also provides a circular knitting machine, characterized in that the circular knitting machine includes the outer Schenker ring as described above, the needle plate as described above, and the main body structure of the needle cylinder as described above.

[0028] The positive and progressive effects of this invention are as follows: The laser hardening method and related components for improving the local abrasion resistance of circular knitting machines of the present invention have at least the following advantages: This invention applies a precise and controllable laser hardening process to the core friction areas of the outer Schenck ring, needle plate, and needle cylinder of a circular knitting machine. On the one hand, at the process level, it achieves precise customization of the hardened layer depth and hardness, minimal workpiece deformation, no need for customized tooling to adapt to multiple specifications of parts, and environmentally friendly and efficient processing. It solves the inherent defects of traditional carburizing and quenching, such as easy brittleness, uncontrollable hardened layer of induction hardening, and poor processing flexibility. On the other hand, at the product level, it significantly improves the wear resistance and service life of the core moving parts, avoids quality defects such as vertical stripes and dark patterns on the fabric surface caused by friction indentations, and reduces subsequent finishing costs and equipment maintenance costs, taking into account multiple requirements of processing feasibility, product performance, and economy. Attached Figure Description

[0029] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features, wherein: Figure 1 This is a schematic cross-sectional view of the three-dimensional structure of the needle cylinder in one embodiment of the circular knitting machine of the present invention.

[0030] Figure 2 This is a cross-sectional structure and laser quenching schematic diagram of an embodiment of the outer Schenck loop of the circular knitting machine of the present invention.

[0031] Figure 3 This is a cross-sectional structure and a schematic diagram of laser quenching of a needle plate of a circular knitting machine according to an embodiment of the present invention.

[0032] Figure 4 This is a cross-sectional structure and a laser quenching schematic diagram of an embodiment of the main body structure of the needle cylinder of the circular knitting machine of the present invention.

[0033] Figure 5 This is a cross-sectional structure and a laser quenching schematic diagram of another embodiment of the main structure of the needle cylinder of the circular knitting machine of the present invention.

[0034] Figure 6 This is a schematic flowchart of an embodiment of the laser quenching method for improving the local wear resistance of a circular knitting machine according to the present invention.

[0035] Figure 7 This is a schematic diagram of the laser quenching spot layout on the upper surface of a disc-shaped component in one embodiment of the laser quenching method for improving the local wear resistance of a circular knitting machine according to the present invention.

[0036] Figure 8 This is a schematic diagram of the laser quenching spot layout on the upper surface of a cylindrical component in one embodiment of the laser quenching method for improving the local wear resistance of a circular knitting machine according to the present invention.

[0037] Figure 9This is a schematic cross-sectional view of the needle plate layout of an embodiment of the needle plate of the circular knitting machine of the present invention.

[0038] [Attached image labels]

[0039] 100. Laser beam

[0040] 110. Light spot

[0041] 200, Outer Schenck Circle

[0042] 210. First trench structure

[0043] 220. First trench bottom platform

[0044] 221. First extension

[0045] 300, needle plate

[0046] 310. Pre-set circumferential annular belt

[0047] 400. Syringe body structure

[0048] 410. Thin-walled structure of the mouth

[0049] 411. Second trench structure

[0050] 412. Second trench bottom platform

[0051] 413. Trumpet-shaped groove

[0052] 414. Second extension

[0053] 500, Quenched Surface

[0054] 510. Hardened area on the outer surface

[0055] 520. Inner end round quenched surface Detailed Implementation

[0056] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0057] Reference will now be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used in all the drawings to denote the same or similar parts. Furthermore, although the terminology used herein is selected from commonly known and used terms, some terms mentioned in this specification may have been chosen by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of the description herein. Moreover, the invention should be understood not only by the actual terminology used, but also by the meaning implied by each term. Also, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale.

[0058] In a circular knitting machine, the needles reciprocate up and down within the cylinder. Due to the horizontal radial tension of the tubular fabric along the upper surface of the Schenker plate, sliding friction occurs in the contact area between the outer end of the cylinder nozzle and the needle back. Similarly, the Schenker plate reciprocates horizontally within the groove of the Schenker ring, and the vertical tension of the fabric increases sliding contact friction between the bottom surface of the head and tail of the Schenker plate and the bottom surface of the Schenker groove. This friction can lead to wear and indentations in the cylinder assembly due to factors such as service life, lubrication effectiveness, fabric tension, and machine maintenance frequency.

[0059] Laser hardening of parts is a precision heat treatment process that uses a high-energy-density laser beam to rapidly heat the surface of a part, followed by self-cooling of the substrate to achieve hardening. The core process includes pretreatment → clamping and positioning → laser scanning heating → rapid cooling → post-processing and inspection. The entire process is precisely controllable with minimal deformation. Figure 6 As shown in the image.

[0060] See Figure 6 This invention provides a laser hardening method for improving the local abrasion resistance of a circular knitting machine, the laser hardening method comprising the following steps: Step S1: Perform appearance and dimensional inspection on the parts to be quenched, conduct material analysis to determine matching process parameters, and perform preheating treatment on the parts to be quenched; perform surface pretreatment on the parts to be quenched.

[0061] Step S1 above is a preliminary preparation and preprocessing step. Preferably, step S1 includes the following steps: Step S 11 First, confirm that the part to be quenched is free of cracks, pores, and deformation; measure the dimensions of the area to be quenched; and determine the required depth and hardness of the hardened layer. Second, confirm the steel grade of the part to be quenched, assess its hardenability, and formulate matching process parameters. Third, normalize the part to be quenched.

[0062] Step S 12 First, wipe the surface of the parts to be quenched to remove oil, grind to remove rust and remove oxide scale, and ensure that the surface is dry and clean. Then, apply a light-absorbing coating to the surface of the parts to be quenched to improve the laser absorption rate. Finally, pass an inert gas through the surface of the parts to be quenched for protection.

[0063] The above step S 11 The preferred procedures for the inspection and evaluation of syringe workpieces are as follows: Appearance and dimensional inspection: Confirm that the parts are free of cracks, pores, and deformation, measure the dimensions of the quenched area, and clarify the depth and hardness requirements of the hardened layer.

[0064] Material analysis: Confirm the steel grade, determine hardenability, and formulate matching process parameters.

[0065] Preparatory heat treatment: Normalize the syringe parts first to refine the grains, reduce internal stress, and improve the stability of laser quenching.

[0066] The above step S 12 For the surface pretreatment step, the preferred operation is as follows: Cleaning and stain removal: Wipe with alcohol / acetone to remove oil, sand with sandpaper to remove rust and oxide scale, and ensure the surface is dry and clean.

[0067] Apply a light-absorbing coating: The laser reflectivity of metal surfaces is 60%-90%, so a graphite emulsion or phosphate coating needs to be applied to increase the absorption rate to over 80%.

[0068] Protective treatment: Purge with nitrogen or argon gas to prevent oxidation during heating.

[0069] Step S2: Clamp the part to be quenched, plan the laser scanning path and preset the laser process parameters.

[0070] Step S2 above is the clamping and programming positioning step. Preferably, step S2 includes the following steps: Step S 21 The parts to be quenched are fixed to the CNC worktable by tooling clamping; Step S 22 Plan the scanning path and set the spot overlap rate to ensure the hardened layer is continuous and uniform; Step S 23 1. Pre-set laser process parameters to match the requirements of the material and the hardened layer; laser process parameters include laser power, scanning speed, spot diameter, and defocusing amount.

[0071] The above step S 21 For the tooling clamping process, the preferred operation is as follows: The parts are fixed on the CNC worktable (rotary / five-axis linkage), and thin parts are protected from deformation with fixtures to ensure that the quenching area is precisely aligned with the laser focus.

[0072] The above step S 22 For programming paths, the preferred steps are as follows: Plan the scanning path (parallel / spiral / partitioned) according to the shape of the syringe, and set the spot overlap rate to ensure that the hardened layer is continuous and uniform.

[0073] The above step S 23 For parameter presetting steps, the preferred operation is as follows: Input laser power, scanning speed, spot diameter, defocusing amount, and matching material and hardening layer requirements.

[0074] Step S3: The laser beam scans the area to be quenched along a preset path to reach the target temperature. After the laser beam is removed, rapid cooling is performed to complete the quenching process.

[0075] Step S3 above is the laser hardening core processing step. Preferably, step S3 includes the following steps: Step S 31 The laser beam rapidly heats the surface layer to the austenitizing temperature. The heating rate must ensure that only the surface layer undergoes a phase transformation, while the substrate temperature remains below the phase transformation temperature.

[0076] Step S 32 The laser beam scans at a uniform speed along a preset path, controlling the heat input power and heat input speed to ensure a uniform hardened layer.

[0077] Step S 33 Once the laser beam is removed, the high temperature on the surface is cooled through heat conduction to the substrate, transforming austenite into martensite.

[0078] Preferably, see Figure 7 and Figure 8 In step S 31 In the laser beam, the spot 110 is rectangular in shape, and the laser beam is focused on the surface of the component.

[0079] like Figure 7 As shown, when the upper surface of the disk-shaped component is quenched, the laser beam spot 110 is oriented at an angle α with the radius or axial direction of the disk-shaped component.

[0080] like Figure 8 As shown, when the outer surface of the cylindrical component is quenched, the laser beam spot 110 is oriented at an angle β with the axial direction of the disc component.

[0081] The above step S 31 For the rapid heating step, the preferred operation is as follows: A rectangular laser beam is focused onto a surface. For hardening the upper surface of disc-shaped parts, an angle α is required with the radial (or axial) direction; for hardening the outer surface of cylindrical parts, an angle β is required with the axial direction. This is used to solve the tempering problem at the junction of the two ends, such as... Figure 7 and Figure 8 As shown. Energy density > 10 4 W / cm², the surface layer is rapidly heated to the austenitizing temperature (approximately 900-1100℃), with a heating rate of up to 10 5 -10 6 ℃ / s, only surface phase change, low matrix temperature.

[0082] The above step S 32 For the scanning quenching step, the preferred operation is as follows: The laser scans at a uniform speed along a preset path, controlling the heat input: power determines the heating depth, and speed determines the heating time; the two work together to ensure a uniform hardened layer.

[0083] The above step S33 For the rapid cooling step, the preferred operation is as follows: The cooling method is self-cooling; after the laser is removed, the high surface temperature is rapidly cooled through heat conduction from the substrate (cooling rate > 10). 4 (℃ / s), austenite directly transforms into martensite without the need for an external medium.

[0084] Preferably, the step S3 is followed by the following step: Step S4: Perform post-processing on the quenched area, conduct quality inspection, and verify performance.

[0085] Step S4 above is a post-processing and quality inspection step. Preferably, step S4 includes the following steps: Step S 41 Remove residual light-absorbing coating and clean the surface; remove internal stress after quenching; finely grind to ensure dimensions and surface roughness.

[0086] Step S 42 1. Detect surface hardness; 2. Microscopically examine the hardened layer structure; 3. Detect surface cracks and ablation, and measure the deformation; 4. Perform wear resistance and fatigue strength tests.

[0087] The above step S 41 For post-processing steps, the preferred operation is as follows: Cleaning: Remove any remaining light-absorbing coating and clean the surface.

[0088] Stress relief: Generally no tempering is required; high carbon steel / complex parts can be stress relieved at low temperature (150-200℃) to prevent cracking.

[0089] Finishing: Lightly grind parts with high precision requirements (such as the cutting edge of the mold) to ensure dimensions and surface roughness.

[0090] The above step S 42 For the quality inspection steps, the preferred operation is as follows: Hardness testing: Surface hardness is measured using a Rockwell / Vickers hardness tester.

[0091] Hardened layer detection: Depth is measured by microhardness test, and the microstructure (martensite + a small amount of retained austenite) is observed by metallography.

[0092] Defect detection: Visual / penetration inspection of surface cracks and ablation, and coordinate measuring machine measurement of deformation.

[0093] Performance verification: Abrasion resistance and fatigue strength tests were conducted to confirm compliance with standards.

[0094] As a preferred embodiment of the laser quenching method for improving the local wear resistance of a circular knitting machine according to the present invention, the component to be quenched includes an outer Schenker ring 200, a needle plate 300, and a needle cylinder main body structure 400.

[0095] The area to be quenched in the outer Schenck ring 200 is the upper end face of the extension section of the groove bottom structure of the outer Schenck ring 200.

[0096] The area to be quenched in the needle plate 300 is the pre-set circumferential annular belt 310 of the needle plate 300.

[0097] The areas to be quenched in the main body structure 400 of the syringe are the two sides of the thin-walled structure 410 at the top of the syringe body structure 400.

[0098] The following is a specific embodiment of the laser quenching method for improving the local wear resistance of a circular knitting machine according to the present invention.

[0099] For a large circular machine needle barrel with a diameter of 30″ made of 38MnSi4 alloy steel, a standard process flow of local laser quenching that allows direct machine tool application is selected, strictly meeting the following requirements: Quenching hardness: 58~62 HRC; Hardened layer depth: 0.5~1.0 mm; I. Applicable Conditions and Prerequisites The syringe has been precision machined to the required standard in terms of size, roundness, and end face runout; it is free of cracks, air holes, and burrs; only the working surfaces are hardened (the working surface of the syringe needle track and the contact surface of the Schenker plate track, but not the inside of the needle groove).

[0100] II. Pretreatment Process

[0101] Cleaning and degreasing: Thoroughly wipe the quenched area with alcohol / acetone / cleaning agent; ensure that there is no oil, cutting fluid, or impurities.

[0102] Surface pretreatment: lightly polish off the oxide scale without changing the dimensions; uniformly spray / brush on a light-absorbing coating (graphite emulsion or special coating), with a coating thickness of 0.05-0.1 mm, thin and uniform.

[0103] III. Clamping and Positioning

[0104] Special rotary fixture + chuck clamping; control radial and end face runout ≤0.05 mm; laser head vertically aligned with the working surface, fixed focal length.

[0105] IV. Laser Quenching Process Parameters

[0106] Laser power: 2.0~2.4 KW; scanning linear speed: 8~12mm / s; spot diameter: Φ3~4 mm; spot overlap rate: 20%~25%; scanning method: syringe rotation + laser head axial stepping.

[0107] Cooling method: Self-cooling of the substrate, no water or oil spraying required.

[0108] The above process parameters can be stably achieved on 38MnSi4 steel: hardness: 58~62 HRC; hardened layer depth: 0.5~1.0 mm.

[0109] V. Quenching Operation Steps

[0110] Test quenching: Quench a section on the non-working surface of the syringe first, and check: hardness, depth of hardened layer, presence of burns, cracks, and deformation.

[0111] Formal local quenching: Quench only the working surface of the syringe, avoiding the needle groove; continuous circumferential scanning, step by step; ensuring no soft spots, no missed quenching, and no overheating.

[0112] Cooling: After quenching, allow it to air cool to room temperature.

[0113] 38MnSi4 alloy steel generally does not require tempering under these parameters.

[0114] VI. Post-processing

[0115] Remove light-absorbing coating; lightly polish / finish (without altering dimensions)

[0116] Re-inspection: roundness, runout, flatness

[0117] VII. Quality Acceptance Standards

[0118] Surface hardness: 58~62 HRC

[0119] Effective hardened layer depth: 0.5–1.0 mm

[0120] Surface: No cracks, no ablation, no oxidation peeling

[0121] Deformation amount: ≤ 0.05 mm

[0122] This invention relates to a laser quenching method for improving the local wear resistance of circular knitting machines. By applying laser quenching technology, parts can achieve the required hardness with minimal deformation, thus overcoming various drawbacks of traditional heat treatment processes.

[0123] See Figures 1-2 The present invention also provides an outer Schenker ring 200 for a circular knitting machine. The upper part of the outer Schenker ring 200 has a semi-dovetail-shaped first groove structure 210. The lower part of the first groove structure 210 is connected to a first groove bottom platform 220. A first extension section 221 is provided on the inner side of the first groove bottom platform 220. The upper end face of the first extension section 221 is quenched by the laser quenching method described above for improving the local wear resistance of the circular knitting machine.

[0124] In the knitting industry, no heat treatment process is generally performed on the outer Schenck loop 200 structure. However, for machines with high speed requirements, it is necessary to ensure that the bottom of the Schenck loop groove has sufficient hardness and wear resistance.

[0125] In view of this, such as Figure 2 The diagram shows a cross-sectional structure of the Schenker ring seat installed at the upper outer side of the syringe body; this structure is the outer Schenker ring 200 structure. According to production requirements, a circular blank is first forged, then machined and ground to obtain a smooth circular ring with the required dimensional and positional tolerances. Finally, a high-hardness saw blade on a sawing machine is used to evenly divide the grooves radially, forming the first groove structure 210.

[0126] Taking into account the Schenker plate's movement stroke and clamping method, the first groove structure 210 adopts a semi-dovetail-shaped cross-section. This structure ensures that the lower end face has sufficient area for heat treatment, while the protruding structure at the upper end can effectively guide the Schenker plate, ensuring its stability and accuracy by guiding the radial reciprocating motion of the Schenker plate.

[0127] The dimensions of the semi-dovetail portion of the first groove structure 210 can be adjusted according to the stroke and shape of the Schenker plate. Additionally, the upper surface of the first extension 221 is used as the quenching surface 500, and surface hardening is performed using a laser quenching process. The power and spot size of the laser beam can be adjusted accordingly based on actual conditions.

[0128] The semi-dovetail structure of the outer Schenker ring 200 not only satisfies the laser hardening of the low-end contact surface, but also provides support for the movement of the Schenker sheet.

[0129] See Figure 3 and Figure 9 The present invention also provides a needle plate 300 for a circular knitting machine, wherein the preset circumferential annular belt 310 of the needle plate 300 is quenched by the laser quenching method described above for improving the local wear resistance of the circular knitting machine.

[0130] The laser hardening process of the needle plate 300 is similar to that of the outer Schenck ring 200. If... Figure 2 The outer Schenk circle 200 is replaced with Figure 3 The needle plate 300 and the outer Schenker ring 200 can be combined with the main body of the needle cylinder to form a double-sided knitting machine needle cylinder assembly. The needles on the needle plate are evenly arranged in the upper needle groove, and move in accordance with the corresponding trajectory of the needle cylinder needles to form a specific fabric surface from the fed yarn.

[0131] Preferably, this solution reserves a circumferential annular stitch strip of a certain width and flush with the bottom of the knitting groove at the mouth of the needle plate 300 as a pre-set circumferential annular strip 310 for laser quenching process, to ensure the hardness and wear resistance of the bottom surface of the annular strip, and to solve the problem of short life of the needle plate 300 caused by high-speed friction of the knitting needles.

[0132] Figure 9 The diagram shows the knitting operation when the needle plate 300, the main body structure 400 of the needle cylinder, the knitting needles, the Schenker plate, and other structures work together.

[0133] Regarding the syringe body structure 400, the present invention designs the following two structures, such as... Figure 4 and Figure 5 As shown.

[0134] See Figure 4 The present invention provides a cylinder body structure 400 for a circular knitting machine. The upper part of the nozzle thin-walled structure 410 at the top of the cylinder body structure 400 is provided with a second groove structure 411. The lower part of the second groove structure 411 is connected to a second groove bottom platform 412. The inner side of the second groove bottom platform 412 has a trumpet-shaped groove 413. The outer vertical surface of the thin-walled mouth structure 410, the vertical surface above the inner trumpet-shaped slot 413 of the thin-walled mouth structure 410, and the upper surface near the inner side of the second slot bottom platform 412 are quenched using the laser quenching method described above to improve the local wear resistance of the circular knitting machine.

[0135] exist Figure 4 In the middle, the main structure 400 of the syringe is also a pre-forged part that is processed by machining and grinding. Combined with the steel sheets uniformly inlaid in the reserved grooves in the vertical direction of the surface to form several needle receiving cavities, thus forming the second groove structure 411.

[0136] The design of the second groove structure 411 at the top of the syringe body structure 400 corresponds to... Figure 2 The first groove structure 210 in the middle can realize that the tail of the Schenck tablet is placed in the first groove structure 210 of the outer Schenck ring 200, while the head of the Schenck tablet is placed in the second groove structure 411 at the upper end of the syringe body structure 400, thereby ensuring that the Schenck tablet can stably perform reciprocating load action.

[0137] The nozzle thin-walled structure 410 on the upper end face of the syringe body structure 400 is relatively wide. Considering the risk of local shrinkage during local heat treatment, it is designed as a funnel-shaped groove 413.

[0138] The top of the outer end face of the syringe main body 400 undergoes circumferential rotational heat treatment by setting relevant parameters of the laser beam 100, i.e., quenching the outer surface hardened area 510 to achieve the required surface hardness. Addressing the issue of wear between the lower end face of the Schenker disc head and the bottom of the second groove structure 411, the laser beam 100 is angled to ensure the laser beam can irradiate the bottom surface of the groove wall. This allows for hardening treatment of the bottom end face and vertical surface of the groove. Figure 4 The inner end round quenching surface 520 is composed of the bottom end face of the groove and a vertical surface. The vertical surface is the vertical surface above the inner trumpet-shaped groove 413 of the thin-walled structure 410, and the bottom end face of the groove is the upper surface near the inner side of the second bottom platform 412.

[0139] See Figure 5 The present invention provides a cylinder body structure 400 for a circular knitting machine. A second groove structure 411 is provided on the upper part of the nozzle thin-wall structure 410 at the top of the cylinder body structure 400. The bottom surface of the groove structure 411 is connected to a second groove bottom platform 412. A second extension section 414 is provided on the inner side of the second groove bottom platform 412.

[0140] The outer vertical surface of the mouth thin-walled structure 410 and the upper surface of the second extension 414 are quenched using the laser quenching method described above to improve the local wear resistance of the circular knitting machine.

[0141] Figure 5 The main body structure of the syringe 400 and Figure 4 The difference lies in the narrower width of the thin-walled structure 410 at the mouth. Since the total wall thickness remains unchanged, the transverse length of the bottom end face of the Schenker slot can be extended, forming the second extension section 414. It is easy to use the laser beam quenching process of the vertical end face, and only horizontal heat treatment is needed to achieve the hardening requirements.

[0142] The top design of the two syringe body structures 400 enables laser hardening, thereby improving the performance of the parts.

[0143] The present invention also provides a circular knitting machine, which includes the outer Schenker 200 as described above, the needle plate 300 as described above, and the needle cylinder body structure 400 as described above.

[0144] Figure 1 The figure shown is a three-dimensional cross-sectional view of the syringe structure, which consists of the outer Schenker ring 200, the needle plate 300, and the syringe body structure 400.

[0145] This invention utilizes laser quenching technology to perform localized heat treatment on key friction areas such as the needle running grooves and sinker (or needle plate knitting) mating surfaces on needle cylinder components, including the external Schenker ring 200, needle plate 300, and needle cylinder main structure 400. By leveraging the high energy density of the laser beam, selective heating and rapid cooling quenching of localized areas of the components are achieved, forming a high-hardness martensitic structure only in the target working area, thus avoiding component deformation and toughness loss caused by overall heat treatment.

[0146] After laser quenching, the surface hardness of the key friction surfaces of the components can be significantly increased to HRC 58-62, while maintaining the good toughness and impact resistance of the substrate. This makes the wear resistance of the components more than 3 times that of traditional quenching and tempering treatment, effectively extending the service life of the whole machine.

[0147] The laser quenching process used in this invention can be perfectly adapted to the complex annular groove structure in the needle cylinder component, achieving uniform strengthening of the precision mating surfaces such as the side wall and bottom of the needle groove, ensuring the running accuracy and stability of the knitting needle and sinker in high-speed reciprocating motion, and reducing the knitting defect rate.

[0148] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A laser hardening method for improving the local abrasion resistance of a circular knitting machine, characterized in that, The laser quenching method includes the following steps: S1. Perform appearance and dimensional inspection on the parts to be quenched, conduct material analysis to determine matching process parameters, and perform preheating treatment on the parts to be quenched; perform surface pretreatment on the parts to be quenched. S2. Clamp the part to be quenched, plan the laser scanning path and preset the laser process parameters; S3. The laser beam scans the area to be quenched along a preset path to reach the target temperature. After the laser beam is removed, rapid cooling is performed to complete the quenching process.

2. The laser hardening method for improving the local wear resistance of a circular knitting machine as described in claim 1, characterized in that, Following step S3, the following steps are also included: S4. Perform post-processing on the quenched area, conduct quality inspection, and verify performance.

3. The laser hardening method for improving the local wear resistance of a circular knitting machine as described in claim 2, characterized in that, The component to be quenched includes an outer Schenker ring, a needle plate, and a main body structure of the syringe. The area to be quenched in the outer Schenker ring is the upper end face of the extension section of the groove bottom structure of the outer Schenker ring. The area to be quenched on the needle disc is a pre-set circumferential annular band on the needle disc; The areas to be quenched in the main body structure of the syringe are the two sides of the thin-walled structure at the top nozzle of the main body structure of the syringe.

4. The laser hardening method for improving the local wear resistance of a circular knitting machine as described in claim 1, characterized in that, Step S1 includes the following steps: S 11 First, confirm that the part to be quenched is free of cracks, pores, and deformation; measure the dimensions of the area to be quenched; and determine the required depth and hardness of the hardened layer. Second, confirm the steel grade of the part to be quenched, assess its hardenability, and formulate matching process parameters. Third, normalize the part to be quenched. S 12 First, wipe the surface of the parts to be quenched to remove oil, grind to remove rust and remove oxide scale, and ensure that the surface is dry and clean. Then, apply a light-absorbing coating to the surface of the parts to be quenched to improve the laser absorption rate. Finally, pass an inert gas through the surface of the parts to be quenched for protection.

5. The laser hardening method for improving the local wear resistance of a circular knitting machine as described in claim 1, characterized in that, Step S2 includes the following steps: S 21 The parts to be quenched are fixed to the CNC worktable by tooling clamping; S 22 Plan the scanning path and set the spot overlap rate to ensure the hardened layer is continuous and uniform; S 23 1. Pre-set laser process parameters to match the requirements of the material and the hardened layer; laser process parameters include laser power, scanning speed, spot diameter, and defocusing amount.

6. The laser hardening method for improving the local wear resistance of a circular knitting machine as described in claim 1, characterized in that, Step S3 includes the following steps: S 31 The laser beam rapidly heats the surface to the austenitizing temperature. The heating rate must ensure that only the surface undergoes a phase transformation, while the substrate temperature remains below the phase transformation temperature. S 32 The laser beam scans at a constant speed along a preset path, controlling the heat input power and heat input speed to ensure a uniform hardened layer. S 33 Once the laser beam is removed, the high temperature on the surface is cooled through heat conduction to the substrate, transforming austenite into martensite.

7. The laser hardening method for improving the local wear resistance of a circular knitting machine as described in claim 6, characterized in that, Step S 31 In this design, the laser beam has a rectangular spot shape and is focused on the surface of the component. When quenching the upper surface of a disk-like component, the laser beam spot is oriented at an angle α with the radius or axial direction of the disk-like component. When quenching the outer surface of cylindrical parts, the laser beam spot is oriented at an angle β with the axial direction of the disc-shaped parts.

8. The laser hardening method for improving the local wear resistance of a circular knitting machine as described in claim 2, characterized in that, Step S4 includes the following steps: S 41 Remove residual light-absorbing coating and clean the surface; remove internal stress after quenching; perform fine finishing and polishing to ensure dimensional accuracy and surface roughness; S 42 1. Detect surface hardness; 2. Microscopically examine the hardened layer structure; 3. Detect surface cracks and ablation, and measure the deformation; 4. Perform wear resistance and fatigue strength tests.

9. An outer Schenker loop for a circular knitting machine, characterized in that, The upper part of the outer Schenker ring of the circular knitting machine has a semi-dovetail-shaped first groove structure. The lower part of the first groove structure is connected to a first groove bottom platform. A first extension section is provided on the inner side of the first groove bottom platform. The upper end surface of the first extension section is quenched using the laser quenching method for improving the local wear resistance of the circular knitting machine as described in any one of claims 1-8.

10. A needle plate for a circular knitting machine, characterized in that, The needle plate of the circular knitting machine has a pre-set circumferential annular belt at its opening. The pre-set circumferential annular belt is quenched using the laser quenching method described in any one of claims 1-8 to improve the local wear resistance of the circular knitting machine.

11. A cylinder body structure for a circular knitting machine, characterized in that, The upper part of the thin-walled structure of the nozzle at the top of the main body of the syringe is provided with a second groove structure, and the lower part of the second groove structure is connected to a second groove bottom platform. The inner side of the second groove bottom platform has a funnel-shaped groove. The outer vertical surface of the thin-walled mouth structure, the vertical surface above the inner trumpet-shaped slot of the thin-walled mouth structure, and the upper surface near the inner side of the second slot bottom platform are quenched using the laser quenching method for improving the local wear resistance of a circular knitting machine as described in any one of claims 1-8.

12. A cylinder body structure for a circular knitting machine, characterized in that, The upper part of the thin-walled structure at the top of the syringe body is provided with a second groove structure, the bottom surface of the second groove structure is connected to a second groove bottom platform, and a second extension section is provided on the inner side of the second groove bottom platform. The outer vertical surface of the thin-walled structure of the mouth and the upper surface of the second extension are quenched using the laser quenching method for improving the local wear resistance of a circular knitting machine as described in any one of claims 1-8.

13. A circular knitting machine, characterized in that, The circular knitting machine includes the outer Schenker as described in claim 9, the needle plate as described in claim 10, and the cylinder body structure as described in claim 11 or 12.

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