A multi-layer pleated sheet processing process

Abstract

The application discloses a kind of multilayer pleated sheet processing technology, belong to textile filling technical field, solve the pleated sheet processing when pressure roller bearing pitting vibration frequency falls in the maximum interval of internal friction of terylene, fiber residual additional deformation, tension control system amplifies vibration as sustained tension oscillation, cause periodic shallow wrinkle zone to appear on cloth surface longitudinal, interlayer air retention amount is uneven, clothing warm-keeping performance flaw Problem, including the following steps: S1 preparation single layer grammage is 5.0±0.3g / m² terylene ultra-thin non-woven fabric.The application mixes silica or calcium carbonate in terylene chip to change the viscoelastic properties of fiber, increase the preheating process to adjust the internal friction response interval, and add a specific frequency electrical signal filter in the tension control system, to avoid the superposition and amplification of material properties, equipment vibration and control fluctuation, prevent regular shallow pleats and uneven heat preservation effect.

Description

Technical Field

[0001] This invention relates to the field of textile filling technology, and more particularly to a multi-layer pleated sheet processing technology. Background Technology

[0002] Pleated sheets are a type of thermal insulation filling material for clothing, made from polyester meltblown nonwoven fabric as the base material through multi-layer lamination and permanent pleating and shaping processes. The weight of a single layer of base fabric is controlled at 10 to 20 grams per square meter. Its manufacturing process involves polyester chips being extruded by a screw extruder, conveyed by a metering pump, spun into fibers by a spinneret, side-blown cooling, web laying, and winding to obtain an ultra-thin nonwoven base fabric. Then, two or more layers of base fabric are laminated and fed into patterned pressure rollers, where they are instantaneously extruded at 100 to 120°C to form three-dimensional pleats. They are then steam-set at 150 to 160°C to allow the molecular chains to relax and recrystallize under the constraint of the pleated pattern. Finally, the shape is fixed by multi-roller cooling.

[0003] The outer layers of the finished product have a pleat depth of 2 to 6 mm, the middle layer has a pleat depth of 0.5 to 4.5 mm, and the pleat area accounts for 70 to 100%. The differentiated structure of deep outer layers and shallow inner layers creates abundant interlayer cavities to trap still air, thereby providing good insulation.

[0004] Meanwhile, the material is lightweight, compression resistant, washable, and does not leak threads. It can be used with highly breathable fabrics to improve garment comfort, and its woven stretch allows it to fit snugly with elastic fabrics. After being quilted along the folds, it is easy to cut and sew garments.

[0005] When the pleated fabric is processed on a production line with a speed of 20 m / min, a roller diameter of 300 mm, and a weight of 15 g / m², the roller bearings experience early pitting after prolonged operation, which triggers pulse vibrations. The frequency of these vibrations falls within the range where polyester experiences the greatest internal friction at pleating temperatures of 100 to 120°C. This causes the fibers to be less prone to rebound after being subjected to periodic external forces, resulting in residual deformation. At the same time, the tension control system of the production line, in its pursuit of rapid response, not only fails to suppress the pulse vibrations but also synchronizes its adjustment actions with the disturbances and amplifies them into continuous small-amplitude tension oscillations. This results in periodic shallow wrinkles with a spacing of approximately 70-85 mm and a pleat depth of approximately 20% to 30% left in the longitudinal direction of the fabric. This leads to uneven air retention between the layers of the pleated fabric, ultimately resulting in defects in the warmth retention performance of the finished garment.

[0006] Therefore, a multi-layer pleated sheet processing technology is proposed to solve or alleviate the above problems. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a multi-layer pleated sheet processing technology.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A multi-layer pleated sheet processing technology includes the following steps: S1 was used to prepare a single-layer ultrathin polyester nonwoven base fabric with a basis weight of 5.0 ± 0.3 g / m²; S2 involves stacking at least three layers of polyester ultra-thin nonwoven base fabric under constant tension at a winding tension of 0.5-1.0 N / cm width to form a laminated fiber web with a total basis weight of 15±1 g / m². The tension control system incorporates a notch filter, the difference between the center frequency of the notch filter and the characteristic frequency of the bearing inner ring of the pressure roller does not exceed ±0.5 Hz, and an open-loop gain attenuation of not less than 20 dB is introduced in the ±0.75 Hz neighborhood of this characteristic frequency. The closed-loop crossover frequency of the tension control system is not greater than 1 Hz and the phase margin is not less than 50°. S3 performs composite heating preheating on the laminated fiber web to achieve a surface temperature of 130±3℃ and a core temperature of not less than 125℃; S4 mechanically pleats the preheated multilayer fiber web at a production speed of 20±0.3m / min under conditions of a roller surface temperature of 135±3℃ and a roller gap linear pressure of 80-120N / cm, forming a multilayer pleated nonwoven fabric with a three-dimensional pleated texture; S5 uses a polytetrafluoroethylene-coated mesh belt to carry out high-temperature steam penetration shaping of multi-layer pleated nonwoven fabric under steam temperature of 155-160℃ and steam pressure of 3-5 bar, so that the fiber molecular chains can relax and recrystallize under the constraint of the pleated shape, forming shape memory. S6 uses a two-stage cooling roller assembly to perform gradient cooling on the shaped multi-layer pleated nonwoven fabric. The roller surface temperature in the first cooling zone is 35-40℃, and the roller surface temperature in the second cooling zone is 12-18℃. The temperature range of the two cooling zones avoids the glass transition temperature range of polyester, which is 70-80℃. S7 winds up the cooled multi-layered pleated nonwoven fabric and monitors the bearing condition of the pressure rollers online.

[0009] Preferably, step S1, which prepares a single-layer polyester ultrathin nonwoven base fabric with a basis weight of 5.0 ± 0.3 g / m², specifically includes the following steps: Polyester chips with an intrinsic viscosity of 0.64-0.68 dL / g and a moisture content of ≤30 ppm are melt-extruded at 260-285℃. No more than 2.0% by weight of silica or barium sulfate is added to the polyester chips as a matting agent or spinning aid. The melt is pumped to the spinning box at a post-pump pressure of 15-18 MPa by a metering pump, and extruded into fibers through a spinneret with an orifice diameter of 0.2-0.3 mm at 280±1℃; Cooling is achieved using side-blowing air at a temperature of 15±2℃ and a wind speed of 0.3-0.8m / s; A single-layer fiber web with a basis weight of 5.0±0.3g / m² is formed using a web-forming machine with a web-forming linear speed of 15.0±0.2m / min as the base fabric for polyester ultra-thin nonwoven fabric.

[0010] Preferably, step S3 involves composite heating and preheating of the laminated fiber web, specifically including the following steps: The laminated fiber web is heated by a combination of infrared radiation and hot air convection. The heating section is 2.0-2.5m long, the peak wavelength of the infrared radiation is 1.0-1.2μm, the infrared radiation power is 40%-50%, the hot air temperature is 140-160℃, and the wind speed is 1.0-1.5m / s. The hot air blows from both the top and bottom sides of the laminated fiber web. The surface temperature of the preheated polyester ultrathin nonwoven base fabric is 130±3℃, and its core layer temperature is not lower than 125℃.

[0011] Preferably, step S4 involves mechanically pleating the preheated laminated fiber web at a production speed of 20±0.3 m / min under conditions of a roller surface temperature of 135±3℃ and a roller gap linear pressure of 80-120 N / cm, specifically including the following steps: Mechanical pleating is achieved using a roller pleating machine that combines patterned rollers and elastic rollers. The patterned rollers have a diameter of 300mm and their surfaces are etched to create raised and recessed patterns. The outer layer of the elastic rollers is coated with a high-temperature resistant elastic material with a Shore D hardness of 60-70. The surface temperature of both the patterned and elastic rollers is 135±3℃, and the roller gap linear pressure is 80~120N / cm. This results in a multi-layered pleated nonwoven fabric with a pleat depth of 3-5mm on both sides, a pleat depth of 1-3mm in the middle layer, and a pleated area ratio of 70%-100%.

[0012] Preferably, step S5 involves high-temperature steam penetration and shaping of multi-layered pleated nonwoven fabric under steam temperature of 155-160℃ and steam pressure of 3-5 bar, using a polytetrafluoroethylene coated mesh belt as a support. This allows the fiber molecular chains to relax and recrystallize under the constraint of the pleated morphology, forming morphological memory. Specifically, this includes the following steps: High-temperature steam penetration shaping is carried out under conditions of steam temperature of 155~160℃ and steam pressure of 3~5bar, with an effective steam treatment section length of ≥4m and a net steam contact time of ≥12 seconds at a linear velocity of 20±0.3m / min synchronized with the production speed. Multi-layered pleated nonwoven fabric is laid on a polytetrafluoroethylene coated glass fiber conveyor belt and passes through the steam section. The traction tension it experiences is less than 0.3 N / cm width. Under the plasticizing effect of water molecules and thermal activation, the polyester fibers transform the thermoplastic deformation formed by mechanical force into morphological memory locked by the crystalline structure.

[0013] Preferably, step S6 involves gradient cooling of the shaped multi-layered pleated nonwoven fabric using a two-stage cooling roller assembly, specifically including the following steps: Multi-layer pleated nonwoven fabric is cooled for ≥18 seconds by a two-stage cooling roller combination at a linear speed synchronized with the pleating speed; The roller surface temperature in the first cooling zone is 35-40℃, which reduces the surface temperature of the multi-layer pleated nonwoven fabric from 140-155℃ to 70-80℃. The roller surface temperature in the second cooling zone is 12-18℃, which further reduces the surface temperature of the multi-layer pleated nonwoven fabric from 70-80℃ to no higher than 30℃. Furthermore, the temperature range of the two cooling zones avoids the glass transition temperature range of polyester, which is 70-80℃.

[0014] Preferably, step S7 involves winding up the cooled multi-layered pleated nonwoven fabric, specifically including the following steps: The contact surface winding is achieved by a swing-arm type lightweight contact pressure roller that adheres to the outer surface of the multi-layer pleated nonwoven fabric roll with constant low pressure. The central winding shaft provides auxiliary drive. The initial winding tension is 3.0±0.3N / cm width, and a tension taper is set so that the winding tension decreases linearly by 40%-50% as the roll diameter increases. The maximum winding diameter is ≤600mm, and the contact pressure roller linear pressure is 1-2N / cm.

[0015] Preferably, the online monitoring of the bearing condition of the pressure roller specifically includes the following steps: Vibration signals are collected in real time by an accelerometer installed on the bearing housing of the pressure roller and spectrum analysis is performed to track the vibration amplitude trend in the 4-6Hz frequency band and the sideband and harmonic characteristics of the bearing inner ring passing through the characteristic frequency. When the vibration amplitude in this frequency band exceeds 1.5 times the reference value for 30 consecutive minutes, or when a sideband of the inner ring passing through the frequency appears, or when the harmonic amplitude of the inner ring passing through the frequency shows an upward trend, an early warning is issued, prompting the pressure roller bearing to be inspected.

[0016] The present invention has the following beneficial effects: This invention alters the viscoelastic properties of polyester fibers by pre-mixing a small amount of fine powders such as silica or calcium carbonate into the fibers. This significantly reduces the "absorption amplification" effect of the fibers on vibrations of specific frequencies at operating temperatures. Furthermore, a preheating process is added before the fibers enter the pressure rollers, heating the stacked nonwoven fabric to a higher temperature than before. This changes the fiber's internal friction response range, preventing it from aligning with the bearing vibration frequency. Additionally, an electrical signal filter targeting that specific frequency is added to the tension control system, filtering out periodic disturbances that could derail the tension control system. This avoids the superimposed amplification of material properties, equipment vibration, and control fluctuations, preventing the occurrence of regular shallow wrinkles and uneven insulation. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a vibration early warning diagram for the pressure roller bearing of the present invention; Figure 3 This is a polyester loss factor-temperature curve diagram of the present invention; Figure 4 This is a diagram showing the depth distribution of wrinkles in the wrinkled sheet surface layer of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Furthermore, the terms "first," "second," and "third" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0024] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] A multi-layer pleated sheet processing technology, such as Figure 1 As shown, it includes the following steps: S1 prepares a single-layer polyester ultrathin nonwoven base fabric with a basis weight of 5.0±0.3 g / m², specifically including the following steps: Polyester chips with an intrinsic viscosity of 0.64-0.68 dL / g and a moisture content ≤30 ppm are melt-extruded at 260-285℃. No more than 2.0% by weight of silica or barium sulfate is added to the polyester chips as an inert inorganic submicron-sized powder as a matting agent or spinning aid, with an average particle size D50 of 0.3-1.0 μm. The maximum particle size is no more than 3μm; the melt is pumped to the spinning box at a post-pump pressure of 15-18MPa by a metering pump, and extruded into fibers through a spinneret with an orifice diameter of 0.2-0.3mm at 280±1℃; it is cooled by side blowing air at a temperature of 15±2℃ and a wind speed of 0.3-0.8m / s; and it is formed into a single-layer fiber web with a basis weight of 5.0±0.3g / m² by a web forming machine with a web forming linear speed of 15.0±0.2m / min, which serves as the base fabric for polyester ultrathin nonwoven fabric; In this process, no more than 2.0% of silica or barium sulfate by total mass is added to the polyester chips, resulting in an average particle size D50 of 0.3-1.0 μm and a maximum particle size of no more than 3 μm. The melt is transported to the spinning box by a metering pump at a post-pump pressure of 15-18 MPa and extruded into fibers through a spinneret with an aperture of 0.2-0.3 mm at 280±1℃. Submicron-sized powder may undergo local sedimentation or agglomeration in the high-viscosity melt due to density differences before extrusion. As a result, the proportion of powder in each fiber is not strictly 2.0%, and the viscoelastic properties of some fibers are close to the undoped state. These fibers may still show strong sensitivity to low-frequency vibrations during the pleating process.

[0026] To address this issue, a notch filter is embedded in the S2 tension control system. The difference between the center frequency of the notch filter and the characteristic frequency of the bearing inner ring of the pressure roller does not exceed ±0.5Hz. An open-loop gain attenuation of no less than 20dB is introduced within the ±0.75Hz neighborhood of this characteristic frequency. Through this hard filtering at the tension control system level, even if local fibers are sensitive to low-frequency vibrations due to uneven powder distribution, the tension path that excites the vibration is cut off by the notch filter. Therefore, even if the fibers are sensitive, they will not receive the amplified disturbance signal transmitted through the tension path. Simultaneously, S3 uses a combination of infrared radiation and hot air convection for the laminated fiber web. Combined heating, with a heating section length of 2.0-2.5m, hot air temperature of 140-160℃, wind speed of 1.0-1.5m / s blowing from both top and bottom. After preheating, the surface temperature of the laminated fiber web is 130±3℃, and the core layer temperature is not lower than 125℃. Preheating pushes the overall fiber temperature from the loss peak area of ​​100-120℃ to above 130℃, pushing the internal friction response range from around 4Hz to the high-frequency area of ​​tens of Hz. Even if some fiber powder is unevenly distributed, under the preheating condition of 130℃, its internal friction peak is generally far away from the bearing pitting vibration frequency. The influence of uneven powder distribution is bypassed through temperature regulation.

[0027] Meanwhile, because the side-blowing air in S1 blows from one side, there is a difference in the cooling rate between the fiber bundle facing the wind source and the leeward side, resulting in differences in the initial crystallinity distribution of fibers at different positions within the fiber bundle. Some low-crystallinity fibers have a low plastic deformation threshold during subsequent pleating and are easily affected by tension fluctuations, resulting in uneven deformation. Therefore, S3 is required to heat the laminated fiber web using a combination of infrared radiation and hot air convection, so that the laminated fiber web receives uniform heating from both sides before pleating. The surface and core temperatures of the fibers reach the target values ​​simultaneously. The initial crystallinity distribution of fibers caused by the cooling difference in S1 is uniformized through thermal activation in the preheating stage, so that all fibers have similar plastic deformation capabilities when entering the pleating process. At the same time, it is also necessary to go through step S5, which uniformly adjusts the non-equilibrium crystallization state formed in the cooling stage of S1 into a stable crystallization structure constrained by the pleat pattern through the recrystallization process of S5. The difference in the initial crystallinity of fibers is eliminated in the uniform recrystallization of S5.

[0028] S2 involves stacking at least three layers of ultra-thin polyester nonwoven base fabric under constant tension at a winding tension of 0.5-1.0 N / cm width to form a laminated fiber web with a total basis weight of 15±1 g / m². The tension control system incorporates a notch filter. The difference between the center frequency of the notch filter and the characteristic frequency of the bearing inner ring of the pressure roller does not exceed ±0.5 Hz. An open-loop gain attenuation of not less than 20 dB is introduced within the ±0.75 Hz neighborhood of this characteristic frequency. Furthermore, the closed-loop crossover frequency of the tension control system is not greater than 1 Hz, and the phase margin is not less than 50°. The notch filter... The center frequency is determined according to the bearing model and production speed of the patterned roller, based on the formula for calculating the bearing inner ring pass frequency, i.e., f=(n / 2)*(1+d*cosα / D)*N, where n is the number of rolling elements, d is the diameter of the rolling elements, D is the bearing pitch circle diameter, α is the bearing contact angle, and N is the number of rotations of the bearing inner ring per second. The attenuation of the notch filter at the center frequency is not less than 25 dB, and the attenuation in the range of 0-2 Hz and above 10 Hz is not greater than 1 dB. The signal sampling frequency of the notch filter is not less than 200 Hz. Among them, after the tension control system is embedded with a notch filter, the attenuation at around 4.2Hz reaches 20 dB. This results in the suppression of all tension disturbance signals in this frequency band, including not only the bearing pulse disturbance that needs to be suppressed, but also the normal response of the tension control system to the effective tension change in this frequency band. In the process of laminated fiber web processing, any instantaneous loss of tension control may cause the fiber web to break or deform significantly.

[0029] Therefore, in S2, it is necessary to limit the "closed-loop crossover frequency to no more than 1Hz". This means that the effective response frequency band of the tension control system is strictly controlled within 0-1Hz, while the notch filter operates around 4.2Hz. The two frequency bands are far apart by more than an order of magnitude. The attenuation of the notch filter will not affect the normal tension adjustment within 0-1Hz. In addition, the "phase margin to no less than 50°" is also limited to ensure that the tension control system has sufficient stability margin in the low-frequency operating range. The unwinding tension itself is set at a width of 0.5-1.0N / cm, which is below 10% of the material's breaking strength, providing sufficient safety redundancy. Even if the notch filter introduces an instantaneous delay, it will not reach the material's safety limit.

[0030] S3 involves composite heating preheating of the laminated fiber web to achieve a surface temperature of 130±3℃ and a core temperature of no less than 125℃. Specifically, this includes the following steps: The laminated fiber web is heated using a combination of infrared radiation and hot air convection. The heating section is 2.0-2.5m long, the peak wavelength of the infrared radiation is 1.0-1.2μm, the infrared radiation power is 40%-50%, the hot air temperature is 140-160℃, and the air velocity is 1.0-1.5m / s. Hot air is blown from both the top and bottom surfaces of the laminated fiber web. After preheating, the surface temperature of the preheated polyester ultrathin nonwoven base fabric is 130±3℃, and its core temperature is no less than 125℃. Furthermore, during the transition from preheating at 130℃ in S3 to the pleating jaws, if the temperature loss is too rapid, the fiber web may fall back to the active temperature range of the loss peak of 100-120℃ before reaching the jaws, and the material sensitization will not be cut off. Therefore, with the cooperation of S3 and S4, the temperature parameters are intentionally linked. The preheating target temperature is 130±3℃, and the surface temperature of the pressure roller is 135±3℃. The temperature difference between the two is only 5℃, and the temperature of the pressure roller is slightly higher than the preheating temperature. This means that even if there is a small amount of heat dissipation in the very short time from the outlet of the preheating section to the entrance of the jaws, it will be immediately replenished to 135℃ after contacting the pressure roller. There is no situation where the fiber web is preheated to 130℃, then falls back to the loss peak area, and finally enters the jaws. At the moment of contact with the jaws, the overall temperature of the fiber web jumps directly to 135℃, completely leaving the 100-120℃ loss peak area.

[0031] S4, under conditions of a roller surface temperature of 135±3℃ and a roller gap pressure of 80-120N / cm, mechanically pleats the preheated multilayer fiber web at a production speed of 20±0.3m / min to form a multilayer pleated nonwoven fabric with a three-dimensional pleated texture. Specifically, the process includes the following steps: mechanical pleating is performed using a roller-type pleating machine that combines patterned rollers and elastic rollers. The patterned rollers have a diameter of 300mm and their surfaces are etched to form raised and recessed patterns. The outer layer of the elastic roller is covered with a high-temperature resistant elastic material with a Shore D hardness of 60-70. The surface temperature of both the patterned and elastic rollers is 135±3℃, and the roller gap pressure is 80-120N / cm. This results in a pleated depth of 3-5mm on both sides of the multilayer pleated nonwoven fabric, a pleated depth of 1-3mm in the middle layer, and a pleated area ratio of 70%-100%. Because the temperature of the pressure roller in S4 is 135℃ and the pressure of the roller gap is 80-120N / cm, the preheated and softened fiber web is subjected to the same action. At this time, the material is in a highly elastic state and plastic deformation is easy to occur. The newly formed folds have some elastic recovery at the moment they leave the pressure roller jaws. This results in the fold shape that is not stable when it just leaves the jaws. If it is not fixed in time, the fold depth will gradually decrease.

[0032] With the help of S5, penetration setting is carried out for more than 12 seconds under steam temperature of 155-160℃ and pressure of 3-5 bar. The water molecules in the steam plasticize the amorphous region of polyester, giving the molecular chains local relaxation ability and rearranging them under the geometric constraints of the wrinkle pattern. At the same time, the temperature is higher than that of S4 (135℃), which promotes the internal rotation and recrystallization of the molecular chains. The 12-second processing time is sufficient for the molecular structure to complete the transformation from mechanical plastic deformation to crystal-locked morphology. As a result, the springback tendency of S4 clamp plastic deformation is completely solidified by the recrystallization process of S5, and the wrinkle morphology is upgraded from reversible deformation to irreversible morphological memory.

[0033] S5 uses a PTFE-coated fiberglass conveyor belt to perform high-temperature steam penetration shaping on multi-layer pleated nonwoven fabric under steam temperatures of 155-160℃ and steam pressures of 3-5 bar. This allows the fiber molecular chains to relax and recrystallize under the constraint of the pleated morphology, forming morphological memory. The specific steps include: high-temperature steam penetration shaping at 155-160℃ and 3-5 bar, with an effective steam treatment section length ≥4m and a net steam contact time ≥12 seconds at a linear speed of 20±0.3m / min synchronized with production speed; the multi-layer pleated nonwoven fabric is laid on a PTFE-coated fiberglass conveyor belt and passes through the steam section with a traction tension of less than 0.3N / cm width. This allows the polyester fibers to transform the thermoplastic deformation caused by mechanical force into morphological memory locked by the crystalline structure under the plasticizing effect of water molecules and thermal activation. During step S5, the temperature of the fiber web exiting from S4 is 135-140℃, and it enters the 155-160℃ environment of S5, a temperature rise of 15-25℃. If this temperature rise occurs under tension, it may cause the instantaneous rebound of the wrinkled shape. The mesh belt bearing of S5 allows the fiber web to completely break away from the tension bearing during the temperature rise. The temperature rise only causes the molecular chain movement to intensify, without causing geometric deformation. The temperature rise is directed to complete the crystallization process, rather than destroying the wrinkled shape.

[0034] S6 uses a two-stage cooling roller assembly to perform gradient cooling on the shaped multi-layer pleated nonwoven fabric. The roller surface temperature in the first cooling zone is 35-40℃, and in the second cooling zone it is 12-18℃. The temperature range of both cooling zones avoids the polyester glass transition temperature range of 70-80℃. Specifically, the process includes the following steps: The multi-layer pleated nonwoven fabric is cooled by the two-stage cooling roller assembly for ≥18 seconds at a linear speed synchronized with the pleating speed; the first cooling zone roller surface temperature of 35-40℃ reduces the fabric surface temperature from 140-155℃ to 70-80℃; the second cooling zone roller surface temperature of 12-18℃ further reduces the fabric surface temperature from 70-80℃ to no higher than 30℃; and the temperature range of both cooling zones avoids the polyester glass transition temperature range of 70-80℃. The polyester web from S5 has a temperature of 140-155℃. If it directly contacts the low-temperature cooling roller, the temperature will exceed 100℃. During rapid cooling, the polyester will inevitably pass through the Tg zone (70-80℃). In this zone, the mobility of molecular chain segments changes drastically. If it is rapidly cooled in the Tg zone, it is easy to leave huge freezing stress in the product. After long-term storage, the wrinkles may slowly rebound. However, the two-stage gradient cooling in S6 sets the roller surface temperature outside the Tg zone for both stages. The first stage roller surface is below the lower edge of Tg, and the second stage roller surface is much lower than the lower edge of Tg. This avoids the situation where the cooling roller surface temperature falls exactly in the Tg zone, causing the fabric to stay in the Tg zone for a long time. At the same time, the sufficiently long cooling path controls the rate of temperature change and prevents local rapid cooling, so that the final product has long-term shape stability. S7 winds up the cooled multi-layer pleated nonwoven fabric, specifically including the following steps: a swing-arm type lightweight contact pressure roller is applied to the outer circular surface of the multi-layer pleated nonwoven fabric roll with constant low pressure to drive the winding to achieve contact surface winding. The central winding shaft provides auxiliary drive. The initial winding tension is 3.0±0.3N / cm width, and a tension taper is set so that the winding tension decreases linearly by 40%-50% as the roll diameter increases. The maximum winding diameter is ≤600mm, and the contact pressure roller linear pressure is 1-2N / cm. The system employs a contact surface winding method, using a swing-arm contact pressure roller to maintain a constant low linear pressure against the outer circumference of the fabric roll. The roll is rotated through surface friction rather than by the strong pull of a mandrel, avoiding tension loss of control caused by the difference in linear speed between the inner and outer diameters during center winding. The center winding tension decreases linearly by 40%-50% as the roll diameter increases; for example, the initial 3.0 N / cm drops to 1.5 N / cm at full roll. The inner layers are not flattened by the accumulated radial pressure from the outer layers. Simultaneously, the maximum winding diameter is limited to within 600 mm, restricting the pressure on the inner layers from the source. The contact pressure roller pressure is 1-2 N / cm, sufficient to maintain stable friction drive and preventing crushing of the pleated structure. This ensures that the three-dimensional pleated structure of the multi-layered pleated nonwoven fabric is preserved intact until the finished product is shipped.

[0035] The bearing condition of the pressure roller is monitored online, specifically including the following steps: Vibration signals are collected in real time using an accelerometer installed on the bearing housing of the pressure roller, and spectrum analysis is performed to track the vibration amplitude trend in the 4-6Hz frequency band and the sidebands and harmonic characteristics of the bearing inner ring passing through the characteristic frequency. An early warning is issued when the vibration amplitude in this frequency band exceeds 1.5 times the reference value for 30 consecutive minutes, or when a sideband of the inner ring passing frequency appears, or when the harmonic amplitude of the inner ring passing frequency shows an upward trend, prompting maintenance of the pressure roller bearing. The piezoelectric accelerometer has a sensitivity of 100mV / g and a response frequency range of 0.5-10kHz. Vibration signals from the pressure roller bearing housing are continuously collected at a sampling rate of not less than 2.5kHz. The collected vibration signals are directly processed via frequency conversion. Spectral analysis yields the original vibration spectrum. Another path undergoes bandpass filtering, followed by envelope processing, and then spectral analysis to obtain the envelope vibration spectrum. After the new pressure roller bearing is assembled, at least six sets of vibration signals are continuously collected under stable operating conditions. The average value of the maximum amplitude of each set of vibration signals in the 4-6Hz frequency band is used as the reference value. During production, an early warning is issued when any of the following situations occur: the maximum amplitude of the vibration signal in the frequency band corresponding to the bearing inner ring passing frequency exceeds 1.5 times the reference value for 30 consecutive minutes; or a clearly rising spectral line appears at the bearing inner ring passing frequency and its harmonics in the envelope vibration spectrum; or sidebands with a spacing of bearing inner ring revolutions per second appear on both sides of the bearing inner ring passing frequency in the original vibration spectrum.

[0036] The notch filter in S2 and the preheating operation in S3 effectively mitigate the effects of the excitation source and bearing pitting. However, the excitation source and bearing pitting themselves are still accumulating. After online monitoring of bearing vibration, the accelerometer collects the vibration signal of the pressure roller bearing housing in real time. Through spectrum analysis, it tracks the vibration amplitude trend of the 4-6Hz frequency band, which is the frequency band where the inner ring of the bearing passes through the characteristic frequency. When any condition is triggered, an alarm will be triggered, identifying early damage before the bearing causes visible defects, prompting planned maintenance, and ensuring that the product quality ultimately passes the test.

[0037] To verify the effectiveness of this process, the following experiment was conducted: Three-layer linkage tests were conducted on a 300 mm patterned pressure roller in a pleated fabric mass production line. First, an acceleration sensor was installed on the outer circle of the pressure roller bearing seat to continuously collect vibration signals and average their power spectra at three life cycle stages: newly installed bearing, early pitting corrosion, and progressive pitting corrosion. Second, ultra-thin nonwoven base fabrics made from unmodified polyester chips and modified chips incorporating submicron inorganic powder according to the present invention were selected and the loss factor evolution curve with temperature was obtained by scanning at a constant heating rate on a dynamic mechanical analyzer. Third, one roll of finished product was taken from each of the conventional process line without a preheating section and without a notch filter embedded in the tension control system, and the process line of the present invention with a preheating section and a notch filter embedded in the system. The surface wrinkle depth was continuously collected at millimeter intervals along the machine direction on the same non-contact optical thickness gauge.

[0038] The three sets of data are presented in the following three charts: like Figure 2 The vibration acceleration amplitude spectrum and the 4–6 Hz monitoring frequency band and early warning reference identification diagram of the pressure roller bearing under three life cycle states shown in the figure demonstrate that by simultaneously tracking the amplitude trend, sideband and harmonics, three complementary conditions, early warning can be given before visible defects appear on the bearing surface, providing sufficient lead time for planned replacement.

[0039] like Figure 3 The curves showing the evolution of loss factors of unmodified polyester and powder-modified polyester with temperature, as well as the location markings of conventional pleating temperature zones and pleating temperature zones in this process, demonstrate that powder modification and preheating are sufficient to prevent vibrational energy from finding an effective residual channel inside the fiber.

[0040] like Figure 4 The diagram shows a comparison of the surface wrinkle depth distribution along the machine direction of the multilayer wrinkled sheet produced by the conventional process and the process of this invention, as well as the identification points of the target area and shallow wrinkles. It can be seen that after this process, shallow wrinkles are eliminated from the source and the amount of interlayer air is uniform along the machine direction.

[0041] In summary, this process first prepares a single-layer nonwoven fabric substrate. Before melt extruding polyester chips, ultrafine inorganic powders such as silica or calcium carbonate, accounting for 0.5% to 2% of the total amount, are uniformly mixed into the chips. The average particle size of these powders is less than one-thousandth of a millimeter. These fine solid particles are uniformly embedded inside the polyester material after fiber forming. When the fiber is in a high-temperature state above 100°C in the subsequent pleating process, these particles will block the large-scale movement of molecular chain segments inside the polyester, which will significantly reduce the material's ability to absorb energy from low-frequency mechanical vibrations. This weakens the fiber's tendency to convert external vibrations into residual deformation from the raw material stage.

[0042] Next, the three layers of ultra-thin base fabric are stacked together under extremely low tension. The tension per centimeter of width is only a few tens of grams, just enough to flatten the fabric without stretching it. At the same time, in the tension control program at this step, several filters are set up in advance to suppress the 4 to 6 Hz frequency signal. The attenuation of the filter in this frequency band reaches more than 20 decibels. In this way, the stacked three-layer fiber web itself is not subjected to tensile damage. And the signal path of the tension control system is equivalent to a pre-set barrier. Even if a weak signal of this frequency from the bearing is mixed into the sensor, the control program will not respond to it, let alone amplify it into periodic tension fluctuations.

[0043] After preheating, the stacked fiber web is heated by infrared heating and hot air blowing from both above and below simultaneously before entering the pressure rollers. This heats the fabric surface to about 130°C, while the hot air temperature is between 140°C and 160°C. This allows the hot air to penetrate from the surface layer to the middle layer, ensuring thorough heating both inside and out. This ensures that after the polyester fiber is heated to 130°C, the frequency range in which it is most sensitive to external periodic forces is pushed from around 4Hz to a high-frequency range of tens of Hz. Meanwhile, the pulse vibration frequency generated by bearing pitting is still slightly above 4Hz. The two frequencies are completely different, so the fiber is no longer particularly sensitive to this vibration and will not suffer from extra deformation due to a single vibration.

[0044] Next, mechanical pleating is performed. The three layers of preheated fiber web are directly fed into a pressure roller with a surface temperature of 135°C and a diameter of 300 mm. Under a linear pressure of 80 to 120 kg per centimeter, three-dimensional pleats are pressed out. The machine speed is maintained at 20 meters per minute. Because the temperature and vibration-sensitive range of the fiber have been adjusted in the previous preheating step, even if there is slight vibration in the bearing during pleating, the fiber can still be pressed out with uniform patterns of consistent depth. There will be no more local pleating that is not deep enough due to vibration interference.

[0045] High-temperature steam setting involves laying the pleated nonwoven fabric flat on a PTFE-coated mesh belt and feeding it into a steam chamber. The fabric remains in steam at 155 to 160°C for at least 12 seconds without being stretched by external forces. The high-temperature steam allows the molecular chains inside the polyester fibers to fully relax and rearrange themselves. The inorganic powder particles previously dispersed in the fibers now act as the starting point for crystallization, helping the molecular chains to form stable microcrystalline regions around them. This transforms the pleated shape from a recoverable hot-pressing deformation into an irreversible form, and the entire pleated structure is completely fixed.

[0046] Then, a two-stage gradient cooling process is performed. First, a cooling roller at 38 to 42°C is used to slowly lower the fabric temperature from 140°C to 70 to 80°C. Then, a cooling roller at 10 to 15°C is used to continue cooling the fabric to below room temperature. During the cooling process, the fabric smoothly passes through the temperature range where polyester materials are most prone to internal stress due to rapid cooling. The pleats do not spring back or shrink after cooling, and the pleat depth on the entire fabric surface remains completely consistent.

[0047] Finally, the winding and online monitoring are carried out. The finished product is rolled up using a surface contact winding method. The winding tension automatically decreases by 40% to 50% as the roll diameter increases. At the same time, an acceleration sensor is installed on the bearing seat of the pressure roller to continuously observe the vibration of the bearing. Once the vibration amplitude of a specific frequency continuously exceeds the normal level, an alert is issued. This ensures that the pleats of the finished product are not flattened during the winding process, and that the tension between layers within the roll is appropriate. Moreover, the health status of the bearing is monitored daily. Even slight pitting is detected and replaced as soon as it appears, instead of waiting until a large number of defective products are produced before the problem is discovered. This ensures that the air retention of each layer of the pleated fabric produced is uniform and consistent, resulting in stable and reliable warmth retention performance when made into clothing.

[0048] Meanwhile, during the conventional processing of pleated fabric, if the pitting vibration frequency of the pressure roller bearing falls within the range of maximum internal loss of polyester, resulting in additional deformation of the fiber residue, the tension control system amplifies the vibration into continuous tension oscillation, causing periodic shallow wrinkles to appear in the longitudinal direction of the fabric. Similarly, due to the random shallow wrinkles, varying depths of local shallow wrinkles, and non-fixed pitch pleat fluctuations caused by various mechanical vibrations on the production line, the longitudinal direction of the fabric will also eventually lead to localized areas where the pleat depth is 10%-30% shallower than normal, a localized decrease in interlayer air retention, and localized abnormalities in the warmth retention of the garment.

[0049] The notch filter in the tension control system of this processing technology has a center frequency that is matched with the inner ring of the pressure roller bearing. It has a 20 dB attenuation in the ±0.75 Hz neighborhood. This neighborhood covers the 3.5-5 Hz frequency band at a speed of 20 m / min. This frequency band happens to cover the low-order components of gear meshing impact, the subharmonics of pressure roller ellipticity runout, the belt seam cycle, and the main components of motor foundation vibration on most conventional production lines. Similarly, all disturbances falling into this frequency band are suppressed equally.

[0050] In addition, preheating to 130℃ removes the polyester from the active temperature range of the 100-120℃ loss peak. This means that regardless of the frequency source of the disturbance, the viscoelastic amplification response of the fiber to low-frequency external disturbances is generally reduced. This is a material end passivation method applicable to all low-frequency vibration disturbances.

[0051] The closed-loop crossover frequency of the tension control system is limited to within 1Hz and the phase margin is not less than 50 degrees. The entire tension control system has sufficient stability margin in all frequency bands above 1Hz, not just at 4.2Hz. As a result, this process can also solve the problem of low-frequency vibration-type local shallow wrinkle defects.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-layer pleated sheet processing technology, characterized in that, Includes the following steps: S1 was used to prepare a single-layer ultrathin polyester nonwoven base fabric with a basis weight of 5.0 ± 0.3 g / m²; S2 involves stacking at least three layers of polyester ultra-thin nonwoven base fabric under constant tension at a winding tension of 0.5-1.0 N / cm width to form a laminated fiber web with a total basis weight of 15±1 g / m². The tension control system incorporates a notch filter, the difference between the center frequency of the notch filter and the characteristic frequency of the bearing inner ring of the pressure roller does not exceed ±0.5 Hz, and an open-loop gain attenuation of not less than 20 dB is introduced in the ±0.75 Hz neighborhood of this characteristic frequency. The closed-loop crossover frequency of the tension control system is not greater than 1 Hz and the phase margin is not less than 50°. S3 performs composite heating preheating on the laminated fiber web to achieve a surface temperature of 130±3℃ and a core temperature of not less than 125℃; S4 mechanically pleats the preheated multilayer fiber web at a production speed of 20±0.3m / min under conditions of a roller surface temperature of 135±3℃ and a roller gap linear pressure of 80-120N / cm, forming a multilayer pleated nonwoven fabric with a three-dimensional pleated texture; S5 uses a polytetrafluoroethylene-coated mesh belt to carry out high-temperature steam penetration shaping of multi-layer pleated nonwoven fabric under steam temperature of 155-160℃ and steam pressure of 3-5 bar, so that the fiber molecular chains can relax and recrystallize under the constraint of the pleated shape, forming shape memory. S6 uses a two-stage cooling roller assembly to perform gradient cooling on the shaped multi-layer pleated nonwoven fabric. The roller surface temperature in the first cooling zone is 35-40℃, and the roller surface temperature in the second cooling zone is 12-18℃. The temperature range of the two cooling zones avoids the glass transition temperature range of polyester, which is 70-80℃. S7 winds up the cooled multi-layered pleated nonwoven fabric and monitors the bearing condition of the pressure rollers online.

2. The multi-layer pleated sheet processing technology according to claim 1, characterized in that, The preparation of a single-layer polyester ultrathin nonwoven base fabric with a basis weight of 5.0±0.3 g / m² by S1 specifically includes the following steps: Polyester chips with an intrinsic viscosity of 0.64-0.68 dL / g and a moisture content of ≤30 ppm are melt-extruded at 260-285℃. No more than 2.0% by weight of silica or barium sulfate is added to the polyester chips as a matting agent or spinning aid. The melt is pumped to the spinning box at a post-pump pressure of 15-18 MPa by a metering pump, and extruded into fibers through a spinneret with an orifice diameter of 0.2-0.3 mm at 280±1℃; Cooling is achieved using side-blowing air at a temperature of 15±2℃ and a wind speed of 0.3-0.8m / s; A single-layer fiber web with a basis weight of 5.0±0.3g / m² is formed using a web-forming machine with a web-forming linear speed of 15.0±0.2m / min as the base fabric for polyester ultra-thin nonwoven fabric.

3. The multi-layer pleated sheet processing technology according to claim 1, characterized in that, S3 involves composite heating and preheating of the laminated fiber web, specifically including the following steps: The laminated fiber web is heated by a combination of infrared radiation and hot air convection. The heating section is 2.0-2.5m long, the peak wavelength of the infrared radiation is 1.0-1.2μm, the infrared radiation power is 40%-50%, the hot air temperature is 140-160℃, and the wind speed is 1.0-1.5m / s. The hot air blows from both the top and bottom sides of the laminated fiber web. The surface temperature of the preheated polyester ultrathin nonwoven base fabric is 130±3℃, and its core layer temperature is not lower than 125℃.

4. The multi-layer pleated sheet processing technology according to claim 1, characterized in that, S4 involves mechanically pleating the preheated laminated fiber web at a production speed of 20±0.3 m / min under conditions of a roller surface temperature of 135±3℃ and a roller gap linear pressure of 80-120 N / cm. The specific steps include the following: Mechanical pleating is achieved using a roller pleating machine that combines patterned rollers and elastic rollers. The patterned rollers have a diameter of 300mm and their surfaces are etched to create raised and recessed patterns. The outer layer of the elastic rollers is coated with a high-temperature resistant elastic material with a Shore D hardness of 60-70. The surface temperature of both the patterned and elastic rollers is 135±3℃, and the roller gap linear pressure is 80~120N / cm. This results in a multi-layered pleated nonwoven fabric with a pleat depth of 3-5mm on both sides, a pleat depth of 1-3mm in the middle layer, and a pleated area ratio of 70%-100%.

5. The multi-layer pleated sheet processing technology according to claim 1, characterized in that, S5, under conditions of steam temperature 155-160℃ and steam pressure 3-5 bar, uses a polytetrafluoroethylene-coated mesh belt to perform high-temperature steam penetration shaping on multi-layered pleated nonwoven fabric. This allows the fiber molecular chains to relax and recrystallize under the constraint of the pleated morphology, forming morphological memory. The specific steps include the following: High-temperature steam penetration shaping is carried out under conditions of steam temperature of 155~160℃ and steam pressure of 3~5bar, with an effective steam treatment section length of ≥4m and a net steam contact time of ≥12 seconds at a linear velocity of 20±0.3m / min synchronized with the production speed. Multi-layered pleated nonwoven fabric is laid on a polytetrafluoroethylene coated glass fiber conveyor belt and passes through the steam section. The traction tension it experiences is less than 0.3 N / cm width. Under the plasticizing effect of water molecules and thermal activation, the polyester fibers transform the thermoplastic deformation formed by mechanical force into morphological memory locked by the crystalline structure.

6. The multi-layer pleated sheet processing technology according to claim 1, characterized in that, S6 uses a two-stage cooling roller assembly to perform gradient cooling on the shaped multi-layered pleated nonwoven fabric, specifically including the following steps: Multi-layer pleated nonwoven fabric is cooled for ≥18 seconds at a linear speed synchronized with the pleating speed by a combination of two cooling rollers. The roller surface temperature in the first cooling zone is 35-40℃, which reduces the surface temperature of the multi-layer pleated nonwoven fabric from 140-155℃ to 70-80℃. The roller surface temperature in the second cooling zone is 12-18℃, which further reduces the surface temperature of the multi-layer pleated nonwoven fabric from 70-80℃ to no higher than 30℃. Furthermore, the temperature range of the two cooling zones avoids the glass transition temperature range of polyester, which is 70-80℃.

7. The multi-layer pleated sheet processing technology according to claim 1, characterized in that... S7 involves winding up the cooled multi-layered pleated nonwoven fabric, specifically including the following steps: The contact surface winding is achieved by a swing-arm type lightweight contact pressure roller that adheres to the outer surface of the multi-layer pleated nonwoven fabric roll with constant low pressure. The central winding shaft provides auxiliary drive. The initial winding tension is 3.0±0.3N / cm width, and a tension taper is set so that the winding tension decreases linearly by 40%-50% as the roll diameter increases. The maximum winding diameter is ≤600mm, and the contact pressure roller linear pressure is 1-2N / cm.

8. The multi-layer pleated sheet processing technology according to claim 1, characterized in that, The online monitoring of the bearing condition of the pressure roller specifically includes the following steps: Vibration signals are collected in real time by an accelerometer installed on the bearing housing of the pressure roller and spectrum analysis is performed to track the vibration amplitude trend in the 4-6Hz frequency band and the sideband and harmonic characteristics of the bearing inner ring passing through the characteristic frequency. When the vibration amplitude in this frequency band exceeds 1.5 times the reference value for 30 consecutive minutes, or when a sideband of the inner ring passing through the frequency appears, or when the harmonic amplitude of the inner ring passing through the frequency shows an upward trend, an early warning is issued, prompting the pressure roller bearing to be inspected.

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