Overlock tape presser foot air gap noise reduction device and overlock machine presser foot feeding mechanism

Abstract

This utility model discloses a noise reduction device for overlock sewing machine presser foot gaps. Using simulation analysis, a finite element model and a dynamic model of the presser foot mechanism module of an overlock sewing machine are built. Through professional noise detection equipment, presser foot noise is collected and analyzed, and the noise contribution spectrum characteristics are identified. The source of the noise generation mechanism is located and confirmed to identify the noise gaps in the overlock sewing machine, thus obtaining an effective and precise presser foot structure for noise reduction. The device includes a noise reduction filling area on the base plate of the presser foot. The noise reduction filling area includes three composite material filling areas: area I, area II, and area III. A composite material filling layer is provided within the noise reduction filling area, with a thickness ratio of 10%-50%. Composite material filling area I is located at the tail end of the presser foot; composite material filling area II is located at the front end area where the base plate of the presser foot contacts the differential teeth; and composite material filling area III is located at the front end of the presser foot.

Description

Technical Field

[0001] This utility model belongs to the field of sewing machine noise reduction technology, specifically relating to a noise reduction device for overlock sewing machine presser foot and a presser foot feeding mechanism for overlock sewing machines. Background Technology

[0002] In modern garment manufacturing, overlock sewing machines, as key equipment, are widely used in the edge sewing and binding processes of various garments. Their high efficiency and stable performance greatly improve the efficiency and quality of garment production. However, the noise generated by overlock sewing machines during the presser foot's empty sewing process has caused many problems for enterprises and garment factories, and has always been an urgent issue for the industry to solve. The noise generated by the presser foot's empty sewing during overlock sewing mainly originates from the high-frequency vibration and collision of mechanical parts under no-load conditions;

[0003] In the existing technology: the current industry's noise reduction methods for gap noise rely on subjective evaluation during the qualitative observation stage: observing the pressure foot agitation amplitude (error ±0.08mm) with a high-speed camera (1000fps) and combining it with subjective human ear scoring (1-10 points), which cannot accurately match the time-frequency domain characteristics of the noise signal.

[0004] Because of the lack of analysis, identification, and demonstration of the true root cause of the pressure foot noise and the key sources of the mixed noise, it is impossible to overcome and improve it in a targeted manner, and it is impossible to effectively reduce the noise. Often, the vibration reduction of all components is done blindly, which is costly and ineffective. Utility Model Content

[0005] This invention aims to provide a noise reduction device for the presser foot of an overlock sewing machine. By using simulation analysis, a finite element model and a dynamic model of the presser foot mechanism module of the overlock sewing machine are built. Through professional noise detection equipment, the presser foot noise is collected and analyzed, and the noise contribution spectrum characteristics are identified. The source of the noise generation mechanism is found and confirmed to be the noise of the overlock sewing machine, thereby obtaining an effective and accurate presser foot structure for noise reduction.

[0006] This application provides a noise reduction device for the presser foot of a seam overlock tape, wherein a noise reduction filling area is provided on the bottom plate of the presser foot;

[0007] The noise reduction filling area includes composite material filling area I, composite material filling area II, and composite material filling area III;

[0008] A composite material filling layer is set in the noise reduction filling area. On the normal cross section of the noise reduction filling area of ​​the pressure foot, the thickness of the composite material filling layer is 10%-50%.

[0009] The composite material filling area I is located at the tail end of the pressure foot, in the wear area of ​​the main feed tooth and auxiliary tooth;

[0010] Composite material filling area II is located in the front end area where the base plate of the pressure foot contacts the differential tooth;

[0011] Composite material filling region III is located at the front end of the pressure foot.

[0012] The technical solution provided in this application also has the following technical features:

[0013] Preferably, in one embodiment of this application, the front end of the presser foot's base plate is provided with an arc surface to guide the fabric to pass smoothly during sewing, and the composite material filling area III is provided on the arc surface.

[0014] Preferably, in one embodiment of this application, the thickness of the base plate of the presser foot is 1-6 mm, and the filling depth of the composite material in the noise reduction filling area is 1-2 mm.

[0015] Preferably, in one embodiment of this application, the composite material filling depth of the noise reduction filling area is 1.5 mm.

[0016] Preferably, in one embodiment of this application, the composite material filling region I partially surrounds the threaded hole I, and the threaded hole I is used to connect the pressure plate.

[0017] Preferably, in one embodiment of this application, the presser foot base plate is equipped with a presser foot bracket, a presser plate, a presser foot claw, and an auxiliary presser foot.

[0018] Preferably, in one embodiment of this application, the composite material filling region II partially surrounds the threaded hole II, and the threaded hole II is used to fix the presser foot claw on the presser foot base plate.

[0019] Preferably, in one embodiment of this application, the presser foot is provided with a U-shaped groove, a bent needle relief groove, a threaded hole II, and a threaded hole III;

[0020] The composite material filling area Ⅲ is located outside the threaded hole Ⅲ, which is used to fix the auxiliary presser foot on the presser foot base plate;

[0021] The bent needle clearance groove is located between threaded hole I and U-shaped groove. The U-shaped groove is used for the mating of the presser foot and the presser foot bracket.

[0022] Preferably, in one embodiment of this application, a presser foot feeding mechanism for an overlock sewing machine includes a presser foot assembly, a toothed feeding assembly, and a presser bar assembly. The presser foot assembly includes the aforementioned overlock tape presser foot noise reduction device.

[0023] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

[0024] 1. This application utilizes simulation analysis and testing methods to accurately locate noise sources, obtain key noise frequency bands, and identify key areas of vibration radiation response; by utilizing vibration response distribution, it identifies target areas for improvement, thereby providing effective improvements for noise reduction; and by strategically deploying composite damping materials, it eliminates or reduces vibration response in target areas, achieving noise reduction effects.

[0025] 2. Based on simulation analysis, this application proposes an improved presser foot mechanism. After implementation, professional testing equipment is used to collect and lock the main noise frequency bands to achieve the expected noise reduction effect, resulting in a presser foot base plate structure with precise noise reduction. Attached Figure Description

[0026] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0027] Figure 1 This utility model relates to a presser foot assembly for a noise reduction device for overlock seams with presser foot;

[0028] Figure 2 This utility model relates to a presser foot base plate mechanism for a noise reduction device with presser foot and open seam covering.

[0029] Figure 3 This is a schematic diagram of a presser foot feeding mechanism for an overlock sewing machine according to the present invention. Figure 1 ;

[0030] Figure 4 This is a schematic diagram of a presser foot feeding mechanism for an overlock sewing machine according to the present invention. Figure 2 ;

[0031] Figure 5 This is a schematic diagram of the contact force between the presser foot and the needle plate.

[0032] Figure 6 A schematic diagram of the contact force between the presser foot and the teeth;

[0033] Figure 7 A contour plot of the maximum stress value of the existing presser foot within one operating cycle;

[0034] Figure 8 The displacement contour map of the presser foot base plate before improvement;

[0035] Figure 9 Vibration response curve for a point on the surface of the existing presser foot base plate;

[0036] Figure 10 Analysis diagram of the ERP of the existing presser foot base plate surface;

[0037] Figure 11 A comparison chart of the noise spectrum of an existing machine with pressure foot under open and no-load conditions;

[0038] Components in the diagram:

[0039] 11-1, Presser foot bracket

[0040] 11-2, Wire clamping plate

[0041] 11-3, Presser foot plate

[0042] 11-4. Foot presser

[0043] 11-5. Auxiliary presser foot

[0044] 11-3-1, Composite Material Filling Region I

[0045] 11-3-2, Threaded Hole I

[0046] 11-3-3, U-shaped groove

[0047] 11-3-4, Bent Needle Clearance Groove

[0048] 11-3-5, Composite Material Filling Region II

[0049] 11-3-6, Threaded Hole II

[0050] 11-3-7, Threaded Hole III

[0051] 11-3-8, Composite Material Filling Region III

[0052] 1. Handwheel

[0053] 2. Spindle

[0054] 3. Main differential gear frame

[0055] 4. Eccentric shaft

[0056] 5. Differential slider assembly

[0057] 6. Differential crank

[0058] 7. Fabric feeding assembly

[0059] 8. Lower blade holder

[0060] 9. Needle plate pad

[0061] 10. Needle plate

[0062] 11. Presser foot assembly

[0063] 12. Compression bar assembly

[0064] 13. Pressing foot arm

[0065] 14. Presser foot shaft

[0066] 15. Displaced teeth

[0067] 16. Main delivery of teeth

[0068] 17. Tooth-lifting slider

[0069] 18. Main feeding linkage

[0070] 19. Main feed crank. Detailed Implementation

[0071] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings. These embodiments are only for illustrating this application and are not intended to limit the scope of this utility model.

[0072] In the description of this utility model, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this utility model. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0073] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 utility model according to the specific circumstances.

[0074] Furthermore, in the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0075] like Figure 1-2 A noise reduction device for overlock seams with presser foot, wherein a noise reduction filling area is provided on the bottom plate of the presser foot;

[0076] The noise reduction filling area includes composite material filling area I 11-3-1, composite material filling area II 11-3-5, and composite material filling area III 11-3-8;

[0077] A composite material filling layer is set in the noise reduction filling area. On the normal cross section of the noise reduction filling area of ​​the pressure foot, the thickness of the composite material filling layer is 10%-50%.

[0078] The composite material filling area Ⅰ11-3-1 is located at the tail end of the pressure foot, in the wear area of ​​the main feed tooth and auxiliary tooth;

[0079] The composite material filling area II11-3-5 is located in the front end area where the base plate of the pressure foot contacts the differential tooth;

[0080] The composite material filling area Ⅲ11-3-8 is located at the front end of the presser foot.

[0081] When implementing this application, the key points are as follows:

[0082] This application aims to improve the noise reduction structure of the presser foot base plate. By combining structural optimization design, material selection, finite element simulation, and acoustic experimental verification, it systematically achieves the noise reduction goal. The complete technical principles and implementation path are as follows:

[0083] Noise source analysis and improvement area identification:

[0084] The noise generated by the presser foot during sewing mainly stems from the following mechanisms: mechanical impact with the fabric / needle plate; amplification of vibration noise caused by its own structural resonance; and "knocking" sound generated by the periodic collision with the feed dog.

[0085] Through simulation, using finite element modeling and surface acoustic radiation analysis, the key areas of vibration response are determined, and damping composite materials are precisely arranged on the base plate structure of the pressure foot.

[0086] By avoiding structural resonance, improving impact resistance, reducing impact noise between the pressure foot and the base plate, the source of noise from the gap was accurately identified, and damping composite materials were matched for the target frequency band to achieve precise noise reduction.

[0087] Specifically, in one embodiment of this application, the thickness of the presser foot's base plate ranges from 1 to 6 mm, and the composite material filling depth of the noise reduction filling area is 1 to 2 mm, which can meet the noise reduction requirements of most sewing equipment.

[0088] Specifically, in one embodiment of this application, the front end of the presser foot's base plate is provided with an arc surface to guide the fabric to pass smoothly during sewing, and the composite material filling area Ⅲ11-3-8 is provided on the arc surface;

[0089] The composite material filling depth in the noise reduction filling area is 1.5mm;

[0090] The composite material filling area Ⅰ11-3-1 partially surrounds the threaded hole Ⅰ11-3-2, and the threaded hole Ⅰ11-3-2 is used to connect the pressure plate 11-2;

[0091] The presser foot base plate 11-3 is equipped with a presser foot bracket 11-1, a presser plate 11-2, a presser foot claw 11-4, and an auxiliary presser foot 11-5.

[0092] The composite material filling area Ⅱ11-3-5 partially surrounds the threaded hole Ⅱ11-3-6, and the threaded hole Ⅱ11-3-6 is used to fix the presser foot claw 11-4 on the presser foot base plate 11-3;

[0093] The presser foot is provided with a U-shaped groove 11-3-3, a bent needle clearance groove 11-3-4, a threaded hole II 11-3-6, and a threaded hole III 11-3-7;

[0094] The composite material filling area Ⅲ11-3-8 is located outside the threaded hole Ⅲ11-3-7, and the threaded hole Ⅲ11-3-7 is used to fix the auxiliary pressure foot 11-5 on the pressure foot base plate 11-3;

[0095] The bent needle clearance groove 11-3-4 is set between the threaded hole I 11-3-2 and the U-shaped groove 11-3-3. The U-shaped groove 11-3-3 is used for the mating of the presser foot and the presser foot bracket.

[0096] Specifically, in one embodiment of this application, a presser foot feeding mechanism for an overlock sewing machine includes a presser foot assembly, a toothed feeding assembly, and a presser bar assembly. The presser foot assembly includes the aforementioned overlock tape presser foot gap noise reduction device.

[0097] Specifically, in one embodiment of this application, the implementation process is as follows:

[0098] First, a rigid body dynamics model of the presser foot mechanism and the toothed feeding structure is built, such as... Figure 3 , 4 As shown, it includes a handwheel 1, a main shaft 2, a main differential tooth holder 3, an eccentric shaft 4, a differential slider assembly 5, a differential crank 6, a fabric feeding assembly 7, a lower knife holder 8, a needle plate pad 9, a needle plate 10, a presser foot assembly 11, a presser rod assembly 12, a presser foot arm 13, a presser foot shaft 14, a differential tooth 15, a main feed tooth 16, a tooth lifting slider 17, a main feed connecting rod 18, a main feed crank 19, and matching components;

[0099] Assign material parameters to each part. The material parameters of a part generally include Young's modulus E (describing the stiffness of the material), Poisson's ratio V (describing the degree of lateral contraction or expansion of the material under tension or compression), and material density P (describing the mass per unit volume of the material).

[0100] The connection relationship between parts is defined by adding kinematic pairs, mainly using revolute joints, cylindrical joints, planar joints, prismatic joints, and fixed joints. Correspondingly, a typical motion mechanism usually also needs to set some contact characteristics and external force loading. In the model of this utility model, the focus is on the noise generation mechanism when the presser foot is not in contact. The presser foot and the teeth, as well as the presser foot and the needle plate, will cyclically generate contact collisions during operation. Therefore, contact characteristics need to be established between them to simulate the collisions between parts in actual operation.

[0101] The Penalty Method, combined with the Coulomb friction model, is used to calculate contact forces. This method, also known as the spring-damped model, simulates contact forces by treating the contact process as the action of a virtual spring and damper. Elastic force simulates the restoring force generated by the deformation of the contacting object (similar to Hooke's law); damping force simulates the energy dissipation during the contact process (such as frictional heat generation during collision); and frictional force is based on Coulomb's law of friction, considering both static and dynamic friction stages.

[0102] Contact types also include point-to-surface contact: approximating the contact surface with discrete points and calculating the penetration depth between the point and the surface; and surface-to-surface contact: discretizing the contact surface into a mesh (such as triangular elements) and calculating the penetration and contact force distribution between elements.

[0103] The contact force Fcontact consists of two parts: the normal force and the tangential frictional force.

[0104] The expression is:

[0105] Fcontact=Fn·n+Ft·t

[0106] n: Unit vector normal to the contact surface;

[0107] t: Tangential unit vector of the contact surface (direction opposite to relative sliding or tendency).

[0108] Based on the parameters required in the above calculation formula, during actual modeling, appropriate values ​​are determined according to the geometric matching relationship and material properties of the two contacting parts. The materials of the needle plate, teeth, and presser foot base plate are all 20Cr. When setting the contact characteristics, the contact characteristics between steel are selected, and the stiffness coefficient is set to 100000, the damping coefficient to 10, the dynamic friction coefficient to 0.2, the stiffness exponent to 1.5, the springback damping coefficient to 0.25, and the maximum step size factor to 10. The contacts between the presser foot base plate plane and the needle plate plane, and between the presser foot base plate plane and the main differential teeth are established respectively.

[0109] The presser arm assembly contains a compression spring that applies force to the presser foot arm, ensuring that the presser foot keeps the fabric pressed tightly during sewing. In the dynamic modeling, a spring force is applied, and the spring stiffness coefficient, damping coefficient, and initial length of the spring are set. The software automatically detects the real-time change in distance between the marked points at both ends of the spring force and calculates the spring force according to Hooke's Law.

[0110] F = -k·x

[0111] F: The elastic force acting on the spring;

[0112] k: The spring constant, which reflects the stiffness of the spring;

[0113] x: Deformation of the spring, i.e., elongation or compression (initial length of the spring set - actual distance between the marked points at both ends of the spring during movement);

[0114] The negative sign (-) indicates that the direction of the elastic force is opposite to the direction of the deformation (the direction of the spring's restoring force always points to the equilibrium position).

[0115] By adding a rotary drive to the spindle and running the dynamic model of the presser foot mechanism, the contact forces between the presser foot base plate and the needle plate, as well as between the presser foot and the teeth, can be obtained in the results file. Figure 5 , 6 As shown in the results curve, the contact force between the presser foot base plate and the needle plate is affected by the tooth shape and the movement of the teeth. The striking force shows an irregular trend and the force value is relatively large. In contrast, the needle plate is fixed to the lower cutter seat through the needle plate pad. The contact area between the presser foot base plate and the needle plate plane is large, and the contact force is more regular and shows periodic changes. The analyzed overlock sewing machine has three adjustable tooth trajectory settings. The main difference between the three settings is the change in tooth height and inclination, corresponding to thin material sewing, medium-thick material sewing, and thick material sewing, respectively. Through kinematic force analysis and comparison in the three modes, it is preliminarily determined that in the thin material sewing mode, the contact force between the presser foot and the needle plate is less than the contact force between the presser foot and the needle plate, and the main noise contribution is the sound of the impact between the teeth and the presser foot. In the medium-thick material sewing and thick material sewing modes, the contact force between the presser foot and the needle plate is greater, and the main noise contribution is the sound of the presser foot hitting the needle plate.

[0116] Figure 5 The contact force between the presser foot and the needle plate. Figure 6 This refers to the contact force between the presser foot and the teeth.

[0117] By using a rigid body dynamics model of the presser foot structure, the contact and collision forces between the presser foot and the needle plate, and between the presser foot and the teeth, were obtained. Further analysis involved establishing a finite element model of the presser foot base plate, making the base plate flexible, and incorporating it into the dynamic model of the presser foot structure to obtain the stress distribution of the presser foot in its working state, identifying the main impact force areas of the presser foot at different times. In this model, the length and width dimensions of the presser foot base plate are approximately 17*50mm. Its 2D mesh size is set to 0.5mm triangular mesh elements, and the 3D mesh type is tetrahedral mesh. 20Cr material parameters are assigned, and rigid elements are established to define the interface points connecting the finite element body of the presser foot base plate and the presser foot frame.

[0118] After setting the parameters, the finite element file of the presser foot plate is converted into a modal neutral file using modal synthesis. This file is then imported into the rigid body dynamics model of the presser foot mechanism, replacing the previously described pure rigid presser foot plate, resulting in a rigid-flexible coupled dynamics model of the presser foot mechanism. The advantage of modal synthesis is that it decomposes the elastic deformation of the flexible body into a series of modes, reducing computational complexity through modal coordinates. Additionally, there is a finite element flexible body (FE-Flex) model, which directly imports finite element meshes and is suitable for complex geometry and local stress analysis. The choice of which flexible body modeling method to use depends on the specific analysis conditions, balancing accuracy and resource efficiency. In the rigid-flexible coupled dynamics model, we focus on the stress distribution region and changes in the presser foot plate, choosing modal synthesis. The flexible body dynamics equations are primarily based on the Lagrange equations, and the motion of the flexible body is expressed as:

[0119] Mq¨+Cq˙+Kq=F+Fcontact

[0120] q: Generalized coordinate vector (including rigid body position / attitude and elastic modal coordinates)

[0121] M: Mass matrix

[0122] C: Damping matrix;

[0123] K: Stiffness matrix

[0124] F: External force (such as gravity, driving force);

[0125] Fcontact: Contact force

[0126] The most commonly used rigid-flexible body contact mechanics model is an extension of the Hertz-Mindlin model, namely Fn=kn·δp+cn·δ˙ (δ>0). The key is the value of δ, which is the depth to which the flexible body node penetrates the surface of the rigid body (calculated by the contact detection algorithm).

[0127] When modeling a rigid-flexible coupling dynamic model, it is essential to confirm that the initial contact state between the presser foot base plate and the teeth and needle plate has not resulted in penetration.

[0128] When establishing a contact model for rigid-flexible coupling, the maximum penetration value should be set to within 0.3.

[0129] Running the rigid-flexible coupling dynamic model yields the stress distribution of the presser foot base plate during operation when it collides with the needle plate and teeth, and provides the vibration displacement response and vibration velocity response of the presser foot base plate surface.

[0130] Figure 7The maximum stress value of the presser foot during one operating cycle is shown in the cloud diagram. The maximum stress is 134.3 MPa.

[0131] Figure 8 This is a displacement cloud diagram of the pressure foot plate caused by collisions and impacts during operation.

[0132] Figure 9 It is the speed response curve of the presser foot plate at a point during operation.

[0133] Sound power is proportional to the square of the vibration velocity. The greater the velocity response, the more sound energy is radiated per unit time, and the stronger the sound is.

[0134] Therefore, at the same frequency, the greater the velocity response, the greater the sound intensity, and the "louder" the sound. For regions with large velocity responses, it is necessary to design and add damping materials to reduce their vibration response.

[0135] After the pressure foot plate is made flexible, surface vibration acoustic radiation ERP is a very useful method for analyzing vibration sound generation. The normal velocity of the vibrating surface, as the sound source, directly determines the sound radiation intensity.

[0136] According to acoustic theory, the normal velocity distribution vn(r,t) of the vibrating surface and the radiated sound pressure p(r,t) satisfy the Rayleigh integral relationship:

[0137]

[0138] Where ρ0 is the medium density, ω is the angular frequency, k is the wave number, and S is the vibrating surface area.

[0139] Figure 10 The surface vibration acoustic radiation ERP cloud map of the presser foot base plate shows that the vibration response is most obvious at the foremost edge of the presser foot base plate during operation.

[0140] Theoretically, the mechanism of sound generation during a collision is the conversion of mechanical energy into sound energy, involving multi-physical field coupling such as solid vibration, sound wave radiation, and energy transfer, including multiple links such as contact mechanics, structural vibration, and acoustic radiation. Its core mechanisms include: elastic modal excitation: the collision force drives the structure to vibrate at its natural frequency; nonlinear effects: the nonlinearity of contact / friction introduces harmonic components; energy transfer: vibrational energy is converted into sound energy through damping dissipation and sound radiation; environmental coupling: the propagation and reflection of sound waves in the medium further modulates the sound characteristics. In engineering, noise suppression can be achieved through modal frequency avoidance, increasing damping, and optimizing the contact interface. Through the above finite element analysis and dynamic analysis of the presser foot mechanism, the magnitude of the collision force and stress distribution characteristics of the presser foot during operation are identified. By comparing the main noise-contributing mechanism with the three-position adjustable teeth, feasible noise improvement schemes are determined. Simultaneously, professional noise testing equipment is used to collect the overall noise of the machine under the open state of the presser foot. Through narrowband spectrum, 1 / 3 octave band, and ColorMap analysis, the main contributing frequency band of the presser foot impact noise is identified as the high-frequency band above 1000Hz.

[0141] Specifically, in one embodiment of this application, Figure 11 The comparison of noise spectrum between the machine with pressure foot open and unloaded states verifies that impact noise has the characteristics of wide bandwidth and rich high-frequency components, and that the amplitude and duration of structural vibration directly determine the noise intensity. High-frequency vibrations are more easily absorbed by damping materials because the friction between molecules is more intense at high frequencies. The role of damping materials is to absorb this energy during vibration transmission, reducing the amplitude and duration of vibration, thereby reducing noise. Therefore, damping materials are effective in this regard. Different damping materials have different effects on vibrations of different frequencies. For wide-band noise, a composite structure of multiple damping materials can be used to better cover noise reduction across various frequency bands. The core parameter for measuring the energy dissipation capacity of a material is its loss factor (η). The larger the η, the higher the efficiency of energy conversion into heat energy. A wide-temperature-range viscoelastic polymer damping material with an η of 0.5 or higher is selected.

[0142] Specifically, in one embodiment of this application, based on the analysis results, through a reasonable presser foot structure design and matching of multi-layer damping composite materials, broadband noise reduction is achieved by superimposing the damping peak frequency bands of different materials; wherein the presser foot assembly structure is as follows: Figure 1 As shown, the detailed structure of the presser foot base plate is as follows: Figure 2As shown. The main material of the presser foot base plate is 20CrMo. Its tail end is the area that directly contacts the main feed tooth and auxiliary teeth. During the entire movement, the front half of the main feed tooth and the rear half of the differential tooth have the most contact with the presser foot. Secondly, the main feed tooth is the first to contact the presser foot, so there are more wear areas between the presser foot and the main feed tooth. Here, a composite material filling area I 11-3-1 is designed, with a filling depth of 1.5mm; the tail end of the presser foot base plate is connected to the pressure plate 11-2 through the threaded hole 11-3-2, and the adjacent area is the bent needle relief groove 11-3-4; the U-shaped groove 11-3-3 is the mating point between the presser foot and the presser foot frame, ensuring that the presser foot base plate is in a flexible rotating state during operation; composite material filling area II 11-3-5 The filling depth is 1.5mm in the front area where the presser foot base plate contacts the differential teeth, which is also the area where stress is relatively concentrated during operation. The presser foot claw 11-4 is fixed to the presser foot base plate 11-3 through threaded hole 11-3-6, and the auxiliary presser foot 11-5 is fixed to the presser foot base plate 11-3 through threaded hole 11-3-7. The frontmost part of the presser foot base plate is an arc surface to guide the fabric to pass smoothly during sewing and reduce resistance. The composite material filling area Ⅲ11-3-8 is designed with a filling depth of 1.5mm. The presser foot base plate includes a total of three composite material filling areas, cleverly designed at the front, middle and rear of the presser foot base plate, effectively reducing the noise caused by high-frequency vibration generated by the periodic collision between the presser foot and the needle plate and teeth during operation.

[0143] This invention utilizes professional simulation analysis methods to construct finite element and dynamic models of the presser foot mechanism module of an overlock sewing machine. This allows for the acquisition of the contact forces between the presser foot and the needle plate during operation, as well as the magnitude of the contact forces with the teeth. It also identifies the main noise-contributing mechanisms in three different tooth trajectory modes. Furthermore, by making the presser foot base plate more flexible, its rigidity can be assessed, and it can be determined whether resonance occurs during operation, leading to a surge in energy and increased noise levels. By analyzing the vibration response of the presser foot surface during operation, a damping embedded structure scheme for the presser foot base plate can be developed. Simultaneously, professional noise detection equipment is used to collect and analyze presser foot noise, identify the noise contribution spectrum characteristics, and pinpoint the broadband spectrum of presser foot impact noise. This allows for the design of presser feet with composite structures of multiple damping materials that provide better vibration absorption in this frequency range.

[0144] In summary, this utility model aims to solve the noise reduction problem of sewing equipment. This application adopts a variety of technical means such as simulation and actual measurement data verification. Through analysis and positioning, the target area for improvement is given. By locking the frequency band and matching the composite noise reduction damping material, the purpose of precise noise reduction and efficient noise reduction is achieved. This utility model provides a more reasonable and effective noise reduction structure for the presser foot plate.

[0145] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. A serging tape presser foot open-slit noise reduction device, characterized in that, The base plate of the presser foot is equipped with a noise-reducing filling area; The noise reduction filling area includes composite material filling area I (11-3-1), composite material filling area II (11-3-5), and composite material filling area III (11-3-8); A composite material filling layer is set in the noise reduction filling area. On the normal cross section of the noise reduction filling area of ​​the pressure foot, the thickness of the composite material filling layer is 10%-50%. The composite material filling area I (11-3-1) is located at the tail end of the presser foot, in the wear area of ​​the main feed tooth and auxiliary tooth; The composite material filling area II (11-3-5) is located in the front end area where the base plate of the pressure foot contacts the differential tooth; The composite material filling area Ⅲ (11-3-8) is located at the front end of the presser foot.

2. The serging tape presser foot open-senning noise reduction device of claim 1, wherein, The presser foot has an arc surface at the front end of its base plate to guide the fabric to pass smoothly during sewing. The composite material filling area Ⅲ (11-3-8) is located on the arc surface.

3. The serging tape presser foot open-senning noise reduction device of claim 1, wherein, The thickness of the presser foot's base plate ranges from 2 to 6 mm, and the composite material filling depth of the noise reduction filling area is 1 to 2 mm.

4. The serging tape presser foot open-senning noise reduction device of claim 3, wherein, The composite material filling depth of the noise reduction filling area is 1.5mm.

5. The serging tape presser foot open-senning noise reduction device of claim 4, wherein, The composite material filling area I (11-3-1) partially surrounds the threaded hole I (11-3-2), and the threaded hole I (11-3-2) is used to connect the pressure plate (11-2).

6. The serging tape presser foot open-senning noise reduction device of claim 4, wherein, The presser foot base plate (11-3) is equipped with a presser foot bracket (11-1), a presser plate (11-2), a presser foot claw (11-4), and an auxiliary presser foot (11-5).

7. The serging tape presser foot open-senning noise reduction device of claim 4, wherein, The composite material filling area II (11-3-5) partially surrounds the threaded hole II (11-3-6), and the threaded hole II (11-3-6) is used to fix the presser foot claw (11-4) on the presser foot base plate (11-3).

8. The serging tape presser foot open-senning noise reduction device of claim 2, wherein, The composite material filling area Ⅲ (11-3-8) is located outside the threaded hole Ⅲ (11-3-7), and the threaded hole Ⅲ (11-3-7) is used to fix the auxiliary presser foot (11-5) on the presser foot base plate (11-3).

9. The serging tape presser foot open-senning noise reduction device of claim 1, wherein, The presser foot is equipped with a U-shaped groove (11-3-3), a bent needle clearance groove (11-3-4), a threaded hole II (11-3-6), and a threaded hole III (11-3-7); The bent needle clearance groove (11-3-4) is set between the threaded hole I (11-3-2) and the U-shaped groove (11-3-3). The U-shaped groove (11-3-3) is used for the mating of the presser foot and the presser foot bracket.

10. A feed mechanism for a presser foot of a serging machine, characterized in that It includes a presser foot assembly, a toothed feeding assembly, and a presser bar assembly. The presser foot assembly includes the overlock tape presser foot noise reduction device as described in any one of claims 1-9.

Images