Manufacturing method for preventing single-board guitar panel from sinking downwards

Abstract

The invention discloses a manufacturing method for preventing a single-board guitar panel from recessing, and relates to the technical field of manufacturing for preventing the single-board guitar panel from recessing, and the method comprises the steps: carrying out the finite element stress simulation of a three-dimensional digital model of the single-board guitar panel, and determining a high-stress region in a stress state; according to the distribution characteristics of the high-stress area, generating a structure model of the bionic support network through topological optimization; preparing a lightweight support net with a bionic structure by adopting an additive manufacturing process based on the structure model; the method comprises the following steps: placing a to-be-processed veneer panel on a rigid mold with a preset curved surface, and carrying out plastic pre-deformation on the to-be-processed veneer panel under the action of vacuum negative pressure to obtain a pre-formed panel; a lightweight supporting net is fixed to a high-stress area on the inner side of the preformed panel; the modularized metal framework with preloaded stress is installed at a preset position in the guitar body to form a reverse acting force system which resists the downward sinking of the panel; and carrying out integral curing treatment on the guitar body provided with the supporting net and the metal framework to complete integrated manufacturing.

Description

Technical Field

[0001] This invention relates to the field of anti-dimpling manufacturing technology for solid wood guitar tops, and in particular to a method for manufacturing anti-dimpling guitar tops. Background Technology

[0002] Anti-concavity technology for solid wood guitar tops refers to a comprehensive process and method designed to systematically prevent, counteract, or compensate for the inward bending (concavity) tendency of solid wood guitar tops under long-term string tension.

[0003] In the field of preventing solid wood guitar top denting, traditional guitars rely solely on the strength of the wood itself and simple internal bracing to resist the immense tension continuously exerted by the strings. Under prolonged stress, the wood undergoes creep and stress relaxation, causing the top to gradually collapse downwards around the bridge, forming a permanent dent or dimple, which severely affects the instrument's structural stability and acoustic performance. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for preventing the top of a solid wood guitar from sagging, solving the problem that traditional guitars rely solely on the strength of the wood itself and simple internal bracing to resist the enormous tension continuously applied by the strings. Under long-term stress, the wood will undergo creep and stress relaxation, causing the top to gradually collapse downwards around the bridge, forming a permanent dent or dimple, which seriously affects the structural stability and acoustic performance of the instrument.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for manufacturing a method to prevent the top of a solid wood guitar from denting, comprising: Finite element stress simulation was performed on a three-dimensional digital model of a single-board guitar top to determine the high-stress areas under stress. Based on the distribution characteristics of high-stress regions, a structural model of a biomimetic support network is generated through topology optimization. Based on the structural model, a lightweight support mesh with a biomimetic structure was fabricated using additive manufacturing technology. The single panel to be processed is placed on a rigid mold with a pre-curved surface, and plastic pre-deformation is carried out by vacuum negative pressure to obtain a pre-formed panel. The lightweight support mesh is fixed to the high-stress area inside the preformed panel. A pre-stressed modular metal frame is installed at a predetermined position inside the instrument body to form a counterforce system that resists the concavity of the panel. The instrument body, which is equipped with a support mesh and metal frame, undergoes an overall curing process to complete integrated manufacturing.

[0007] As a preferred embodiment of the manufacturing method for preventing the concavity of a solid wood guitar top as described in this invention, the specific steps of performing finite element stress simulation on a three-dimensional digital model of the solid wood guitar top to determine the high-stress area under stress are as follows: Obtain a three-dimensional geometric model of the top panel of a single-board guitar, wherein the three-dimensional geometric model includes the precise topological structure of the guitar body outline, sound hole boundaries, and neck connection area; Define the anisotropic material properties of the wood used for the panel, including the modulus of elasticity parallel to the grain, the modulus of elasticity across the grain, the shear modulus, and Poisson's ratio; An equivalent total tension of the string is applied at the center of the bridge in the three-dimensional geometric model. The load is directed along the string axis toward the inside of the instrument to simulate the stress conditions during actual performance. Apply full-degree-of-freedom constraints to the connection boundary between the side panels and the back panel of the instrument body; Based on the fundamental equations of linear elastic statics, a set of governing equations is established in the finite element analysis system, where the stress tensor and strain tensor satisfy the generalized Hooke's law, and the displacement field satisfies the equilibrium differential equations. The solution domain is meshed using tetrahedral or hexahedral meshes. Perform statics analysis to obtain the full-field displacement and stress distribution of the structure under load; Extract the Mises equivalent stress distribution cloud map of the front surface of the panel, and identify and mark continuous areas with stress values ​​exceeding a preset threshold as high stress areas.

[0008] As a preferred embodiment of the manufacturing method for preventing the top of a solid wood guitar from denting as described in this invention, the step of generating a biomimetic support network structural model through topology optimization based on the distribution characteristics of high-stress areas includes the following specific steps: The high-stress region is taken as the design domain, and the material distribution within this region is defined as the optimization variable. An optimization model is established with the goal of minimizing structural mass, and the objective function is the integral of the material volume within the design domain; Structural stiffness constraints are set, requiring that under the same load conditions, the compliance of the optimized structure does not exceed the reference value of the original structure. Compliance is defined as the sum of the products of external load and corresponding displacement. Local stress constraints are introduced, and iterative solutions are performed using a SIMP-based variable density method. By introducing a penalty factor, the intermediate density value is made to approach 0 or 1, thus achieving a clear material distribution. During the iteration process, filtering techniques are used to smooth the design variables; The optimization is considered complete when the rate of change of the objective function and the constraints is lower than the convergence tolerance. The obtained continuous density field is thresholded to generate the geometric contour of the support network; The two-dimensional contour is stretched along the thickness direction and smoothed to construct a three-dimensional support network digital model. Its topology exhibits a hybrid feature of cellular units and truss rods, and the node connections are made with rounded transitions to reduce stress concentration.

[0009] As a preferred embodiment of the manufacturing method for preventing the top of a solid wood guitar from denting as described in this invention, the step of fabricating a lightweight support mesh with a biomimetic structure using additive manufacturing based on a structural model includes the following specific steps: The 3D digital model of the supporting network is converted into STL format and imported into additive manufacturing slicing software; Set the printing layer thickness, scanning speed, laser power, and infill path strategy, where the infill path uses contour parallelism or Hilbert curve to ensure structural continuity; A homogeneous mixture of photosensitive resin and short-cut carbon fiber is selected as the printing material. The composite material is cured by free radical polymerization under ultraviolet light irradiation. In stereolithography equipment, a scraper is used to evenly coat the mixed slurry onto the surface of the liquid tank to form a thin layer; The ultraviolet laser beam is controlled to selectively scan according to the cross-sectional data of the current layer, causing the slurry in the irradiated area to cross-link and solidify, forming a solid thin layer; The work platform descends by a preset layer thickness, and the coating and scanning processes are repeated to build up the shape layer by layer. After all layers have been formed, the printed part is peeled off from the substrate and the uncured residual paste is removed using a cleaning solution; The cleaned components are subjected to secondary ultraviolet light irradiation to allow the unreacted functional groups inside to continue cross-linking, thereby achieving the desired mechanical properties. After post-processing steps such as removing supports and grinding, a lightweight support mesh with precise geometry and stable physical properties is obtained, in which carbon fibers are oriented along the principal stress path.

[0010] As a preferred embodiment of the manufacturing method for preventing the concavity of a solid wood guitar panel according to the present invention, the step of placing the solid wood panel to be processed on a rigid mold with a pre-curved surface, and subjecting it to plastic pre-deformation through vacuum negative pressure to obtain a pre-formed panel, specifically includes the following steps: Prepare a rigid male mold corresponding to the target pre-deformed surface, wherein the mold surface has a calculated micro-convex curvature and its geometry can guide the panel to produce the expected residual deformation. The raw veneer without any internal reinforcement is laid flat on the surface of the male mold; It is covered with a flexible and airtight film, which can stretch with the deformation of the panel without producing wrinkles or local stress concentration. The edges of the film are firmly sealed within the sealing groove of the mold base to form a closed cavity; Start the vacuum pump to extract the air between the film and the mold, so that the air pressure inside the cavity is significantly lower than the external atmospheric pressure, forming a stable negative pressure difference; Under continuous negative pressure, the single board gradually bends and completely fits the mold surface under the pressure difference; Maintaining this bonded state for a period of time allows the wood cell walls to undergo viscoelastic flow and interfiber slippage under continuous stress, thus completing plastic deformation; Slowly release the vacuum, allowing the panel to spring back freely without external force. Due to the incomplete elastic recovery of the wood, the panel retains a stable residual micro-convex shape. The resulting panel is a pre-formed panel, whose initial curvature can effectively counteract the concave trend caused by future string tension, thus preventing deformation from the source.

[0011] As a preferred embodiment of the manufacturing method for preventing the top of a solid wood guitar from sagging as described in this invention, the specific steps of fixing the lightweight support mesh to the high-stress area inside the pre-formed panel are as follows: A high-strength two-component epoxy adhesive is formulated, wherein the high-strength two-component epoxy adhesive has good thixotropy, wettability and high shear strength after curing; Apply the adhesive evenly to the entire bottom surface of the lightweight support mesh; The adhesive-coated support mesh is precisely located in the high-stress area inside the preformed panel according to the design coordinates in the three-dimensional digital model. Apply uniform vertical pressure, and use a pressure block or vacuum bag to make the support mesh fully contact the panel surface, squeeze out the air bubbles in the adhesive layer, and form a continuous and dense adhesive interface. Allow the adhesive to stand at room temperature or with moderate heating to undergo the induction, gelation and post-curing stages, so that the molecular chains are fully cross-linked. After the adhesive joint reaches its initial strength, remove the pressure device to complete the fixation of the support mesh. At this point, the support mesh and the panel form a composite load-bearing system to jointly resist external loads.

[0012] As a preferred embodiment of the manufacturing method for preventing the top of a solid wood guitar from denting as described in this invention, the specific steps of installing a pre-stressed modular metal frame at a predetermined position inside the guitar body to form a counterforce system against the denting of the top are as follows: A U-shaped metal frame is provided, which is made of a lightweight alloy with a high elastic limit and whose free length matches the mounting spacing at the bottom of the instrument's internal cavity. The two ends of the U-shaped metal frame are fixed to the movable clamps of a special tensioning fixture, which is equipped with a displacement measurement and force feedback system. The loading mechanism of the driving tooling applies a controllable axial tensile displacement to the skeleton, causing it to elastically elongate and store strain energy inside. When the tensile displacement reaches the preset value, that is, when the restoring force generated by the skeleton meets the design requirements, a mechanical locking device is used to fix the tooling and maintain the tensile state of the skeleton. The pre-stretched frame, along with the tooling, is placed into the guitar cavity of the guitar that has been assembled. The position is adjusted so that the axis of symmetry of the frame coincides with the center line of the neck, and the two ends are aligned with the predetermined installation points on the inner wall of the side plate. High-toughness structural adhesive is used to firmly bond both ends of the frame to the installation points; Once the adhesive layer has reached sufficient strength, release the locking device of the fixture and remove it from the instrument body. At this point, the metal frame retains the pre-loaded restoring force within the instrument body.

[0013] As a preferred embodiment of the manufacturing method for preventing the top of a solid wood guitar from denting as described in this invention, the steps of integrally curing the guitar body, which is equipped with a support mesh and a metal frame, to complete the integrated manufacturing are as follows: The guitar body, with its internal components installed, is then placed smoothly into a curing chamber with controlled temperature and humidity. Adjust the ambient temperature in the curing chamber to a range suitable for the complete curing of the adhesive, while controlling the relative humidity at a suitable level to prevent additional stress on the wood due to swelling and shrinkage. Maintaining the set temperature and humidity conditions for a sufficient time allows the polymer matrix in all adhesive interfaces to complete the full cross-linking reaction, reaching the glass transition temperature and mechanical strength. Avoid sudden temperature changes and airflow disturbances during the curing process; After the curing cycle is completed, the instrument body is removed from the curing chamber. At this point, the connection between the components has reached a long-term stable state, forming a mechanically coordinated and performance-integrated overall structure, which fundamentally prevents the single-panel panel from denting and deforming during long-term use.

[0014] In a preferred embodiment of the manufacturing method for preventing the top of a solid wood guitar from denting as described in this invention, the restoring force generated by the metal frame under preload is calculated using the following formula: ; in, The elastic modulus of the metal skeleton material. For the cross-sectional area of ​​the skeleton, The applied axial strain; The axial strain is caused by the displacement applied by the tensioning fixture. Compared with the original length of the skeleton Decision, that is ; By precisely controlling displacement , making the restoring force This generates a torque that is opposite to the concave trend of the panel, which partially cancels out the bending moment generated by the chord tension, thereby reducing the net bending moment borne by the panel.

[0015] As a preferred embodiment of the manufacturing method for preventing the top of a solid wood guitar from denting as described in this invention, the topology optimization process of the supporting network structure model is characterized by a mathematical model composed of an objective function and constraints, including: The objective function is to minimize the material volume within the design domain, and its expression is: ; in, This indicates a design space defined based on high-stress areas. This represents the relative density of the material at each point within the space; Constraints include physical equilibrium equations, stiffness requirements, and strength limitations; Stiffness constraints control the total amount of work done by external forces through structural compliance; Strength constraints are achieved by monitoring the stress of finite element elements, and the Mises equivalent stress of all elements does not exceed the allowable stress of wood. The variable density method combined with a penalty factor is used to discretize and solve the continuum topology optimization problem, and the density field is updated iteratively. This continues until the objective function converges and all constraints are satisfied. The obtained optimal density distribution is thresholded and geometrically reconstructed to generate a three-dimensional support network digital model with well-defined boundaries.

[0016] The beneficial effects of this invention are as follows: the structural rigidity and deformation resistance of the panel are improved by using a biomimetic lightweight support mesh and pre-forming process. Furthermore, the introduction of a modular prestressed skeleton forms an active reverse torque, which counteracts the concave tendency caused by string tension from a mechanical perspective. The synergistic effect of each process step achieves super stability without sacrificing the panel's degree of freedom of vibration. This effectively solves the technical problems of heavy reinforcement structures, damaged tone, and poor long-term reliability in traditional processes, extends the lifespan of the guitar, optimizes acoustic response characteristics, and improves the overall performance and manufacturing precision of the instrument. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1This is a flowchart of the manufacturing method for preventing the top of a solid wood guitar from denting in Example 1. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0022] Example 1, referring to Figure 1 This embodiment of the invention provides a method for preventing the top of a solid wood guitar from denting, comprising the following steps: S1. Perform finite element stress simulation on the three-dimensional digital model of the single-board guitar top to determine the high-stress areas under stress. Furthermore, a three-dimensional geometric model of the solid wood guitar top is obtained, which includes the precise topological structure of the guitar body outline, soundhole boundaries, and neck connection area. Define the anisotropic material properties of the wood used for the panel, including the modulus of elasticity parallel to the grain, the modulus of elasticity across the grain, the shear modulus, and Poisson's ratio; An equivalent total tension of the string is applied at the center of the bridge in the three-dimensional geometric model. The load is directed along the string axis toward the inside of the instrument to simulate the stress conditions during actual performance. Apply full-degree-of-freedom constraints to the connection boundary between the side panels and the back panel of the instrument body; Based on the fundamental equations of linear elastic statics, a set of governing equations is established in the finite element analysis system, where the stress tensor and strain tensor satisfy the generalized Hooke's law, and the displacement field satisfies the equilibrium differential equations. The solution domain is meshed using tetrahedral or hexahedral meshes. Perform statics analysis to obtain the full-field displacement and stress distribution of the structure under load; Extract the Mises equivalent stress distribution cloud map of the front surface of the panel, and identify and mark continuous areas with stress values ​​exceeding a preset threshold as high stress areas. It should be noted that by establishing a high-precision finite element simulation model, the mechanical response of the panel under real string tension can be accurately predicted, avoiding misjudgment of the stress state in traditional empirical design. The identified high-stress areas provide clear design input for subsequent topology optimization, ensuring that the layout of the support structure has a scientific basis rather than relying on subjective experience, thus laying a reliable data foundation for the entire anti-dentation mechanism.

[0023] S2. Based on the distribution characteristics of high-stress areas, a structural model of a biomimetic support network is generated through topology optimization; Furthermore, by taking the high-stress region as the design domain, the material distribution within this region is defined as the optimization variable; An optimization model is established with the goal of minimizing structural mass, and the objective function is the integral of the material volume within the design domain; Structural stiffness constraints are set, requiring that under the same load conditions, the compliance of the optimized structure does not exceed the reference value of the original structure. Compliance is defined as the sum of the products of external load and corresponding displacement. Local stress constraints are introduced, and iterative solutions are performed using a SIMP-based variable density method. By introducing a penalty factor, the intermediate density value is made to approach 0 or 1, thus achieving a clear material distribution. During the iteration process, filtering techniques are used to smooth the design variables; The optimization is considered complete when the rate of change of the objective function and the constraints is lower than the convergence tolerance. The obtained continuous density field is thresholded to generate the geometric contour of the support network; The two-dimensional contour is stretched along the thickness direction and smoothed to construct a three-dimensional support network digital model. Its topology exhibits a hybrid feature of honeycomb units and truss rods, and the node connections are made with rounded transitions to reduce stress concentration. The topology optimization process supporting the network structure model is mathematically composed of an objective function and constraints, including: The objective function is to minimize the material volume within the design domain, and its expression is: ; in, This indicates a design space defined based on high-stress areas. This represents the relative density of the material at each point within the space; Constraints include physical equilibrium equations, stiffness requirements, and strength limitations; Stiffness constraints control the total amount of work done by external forces through structural compliance; Strength constraints are achieved by monitoring the stress of finite element elements, and the Mises equivalent stress of all elements does not exceed the allowable stress of wood. The variable density method combined with a penalty factor is used to discretize and solve the continuum topology optimization problem, and the density field is updated iteratively. This continues until the objective function converges and all constraints are satisfied. The obtained optimal density distribution is subjected to threshold extraction and geometric reconstruction to generate a three-dimensional support network digital model with well-defined boundaries; It should be noted that by using high-stress regions as the design domain and defining material distribution as a variable, targeted and resource-concentrated structural optimization was achieved. An optimization model aimed at minimizing mass was established to reduce the weight of the internal structure while ensuring performance. Compliance constraints were used to ensure that the overall stiffness did not deteriorate, guaranteeing the basic deformation resistance of the panels. Local stress constraints were introduced to prevent new weak points from appearing after optimization. The SIMP variable density method combined with a penalty factor was used to make the material distribution clear and convergent, avoiding the manufacturing difficulties caused by intermediate density. The application of filtering technology effectively suppressed numerical instability. A manufacturable support network model was generated through threshold segmentation and geometric reconstruction. Its honeycomb-truss hybrid topology and circular arc transition nodes not only improved the specific stiffness but also reduced local stress concentration, thus improving structural durability.

[0024] S3. Based on the structural model, a lightweight support mesh with a biomimetic structure is prepared using additive manufacturing process; Furthermore, the supporting network 3D digital model is converted into STL format and imported into additive manufacturing slicing software; Set the printing layer thickness, scanning speed, laser power, and infill path strategy, where the infill path uses contour parallelism or Hilbert curve to ensure structural continuity; A homogeneous mixture of photosensitive resin and short-cut carbon fiber was selected as the printing material. The composite material was cured by free radical polymerization under ultraviolet light irradiation. In stereolithography equipment, a scraper is used to evenly coat the mixed slurry onto the surface of the liquid tank to form a thin layer; The ultraviolet laser beam is controlled to selectively scan according to the cross-sectional data of the current layer, causing the slurry in the irradiated area to cross-link and solidify, forming a solid thin layer; The work platform descends by a preset layer thickness, and the coating and scanning processes are repeated to build up the shape layer by layer. After all layers have been formed, the printed part is peeled off from the substrate and the uncured residual paste is removed using a cleaning solution; The cleaned components are subjected to secondary ultraviolet light irradiation to allow the unreacted functional groups inside to continue cross-linking, thereby achieving the desired mechanical properties. After post-processing steps such as removing supports and grinding, a lightweight support mesh with precise geometry and stable physical properties is obtained, in which carbon fibers are oriented along the principal stress path. It should be noted that converting the 3D digital model into STL format and importing it into slicing software is a key interface for realizing digital manufacturing; setting printing parameters appropriately ensures molding accuracy and efficiency; using a composite material of photosensitive resin and chopped carbon fiber balances lightweight, high strength, and good processability; employing stereolithography to form layer by layer can accurately reproduce complex biomimetic mesh structures, breaking through traditional processing limitations; cleaning and secondary curing treatments ensure the chemical stability and mechanical properties of the components; post-processing ensures accurate product dimensions and a smooth surface; the resulting lightweight support mesh has carbon fibers oriented along the principal stress path, improving the load-bearing capacity in key directions and achieving structural-functional integration.

[0025] S4. Place the single panel to be processed on a rigid mold with a preset curved surface, and use vacuum negative pressure to make it plastically pre-deformed to obtain a pre-formed panel. Furthermore, a rigid male mold corresponding to the target pre-deformed surface is prepared, wherein the mold surface has a calculated micro-convex curvature and its geometry can guide the panel to produce the expected residual deformation. The raw veneer without any internal reinforcement is laid flat on the surface of the male mold; It is covered with a flexible and airtight film, which can stretch with the deformation of the panel without producing wrinkles or local stress concentration. The edges of the film are firmly sealed within the sealing groove of the mold base to form a closed cavity; Start the vacuum pump to extract the air between the film and the mold, so that the air pressure inside the cavity is significantly lower than the external atmospheric pressure, forming a stable negative pressure difference; Under continuous negative pressure, the single board gradually bends and completely fits the mold surface under the pressure difference; Maintaining this bonded state for a period of time allows the wood cell walls to undergo viscoelastic flow and interfiber slippage under continuous stress, thus completing plastic deformation; Slowly release the vacuum, allowing the panel to spring back freely without external force. Due to the incomplete elastic recovery of the wood, the panel retains a stable residual micro-convex shape. The resulting panel is a pre-formed panel, whose initial curvature can effectively counteract the concave trend caused by future string tension, thus preventing deformation from the source. It should be noted that a rigid male mold with a preset micro-convex curvature is used to provide precise deformation guidance for the panel; the original veneer begins to deform in a stress-free state, avoiding the influence of initial defects; the flexible and airtight film can uniformly transmit pressure without producing local wrinkles, ensuring consistent deformation; the sealing groove design ensures the long-term stability of the vacuum chamber; the negative pressure difference acts as a driving force uniformly on the entire panel surface, achieving globally controllable deformation; the continuous bonding process promotes viscoelastic flow and fiber slippage in the wood, completing plastic shaping; the slow release of vacuum allows stress to gradually relax, reducing residual internal stress; the formed residual micro-convex shape can be gradually flattened under future chordal tension, thereby offsetting the concave trend during long-term use and achieving active deformation compensation.

[0026] S5. Fix the lightweight support mesh to the high-stress area inside the preformed panel; Furthermore, a high-strength two-component epoxy adhesive was formulated, which has good thixotropy, wettability and high shear strength after curing. Apply the adhesive evenly to the entire bottom surface of the lightweight support mesh; The adhesive-coated support mesh is precisely located in the high-stress area inside the preformed panel according to the design coordinates in the three-dimensional digital model. Apply uniform vertical pressure, and use a pressure block or vacuum bag to make the support mesh fully contact the panel surface, squeeze out the air bubbles in the adhesive layer, and form a continuous and dense adhesive interface. Allow the adhesive to stand at room temperature or with moderate heating to undergo the induction, gelation and post-curing stages, so that the molecular chains are fully cross-linked. After the adhesive joint reaches its initial strength, remove the pressure device to complete the fixation of the support mesh. At this time, the support mesh and the panel form a composite load-bearing system to jointly resist external loads. It should be noted that a high-performance two-component epoxy adhesive is formulated to ensure that the adhesive layer has excellent bonding strength and durability; uniform application of the adhesive ensures uniform stress at the interface; the support mesh is precisely positioned based on a three-dimensional digital model to accurately reproduce the design intent; vertical pressure is applied and air bubbles are removed by pressing with blocks or vacuum bags to form a dense and defect-free adhesive layer; static curing under suitable conditions allows the adhesive to fully cross-link and achieve optimal performance; the fixing method forms a rigid-flexible coupled composite structure between the support mesh and the panel, which enhances local rigidity without affecting the overall vibration characteristics and effectively improves the resistance to collapse.

[0027] S6. Install the pre-stressed modular metal frame into the predetermined position inside the instrument body to form a counterforce system against the concavity of the panel. Furthermore, a U-shaped metal frame is provided, wherein the U-shaped metal frame is made of a lightweight alloy with a high elastic limit, and its free length matches the mounting spacing at the bottom of the instrument's internal cavity; The two ends of the U-shaped metal frame are fixed to the movable clamps of a special tensioning fixture, which is equipped with a displacement measurement and force feedback system. The loading mechanism of the driving tooling applies a controllable axial tensile displacement to the skeleton, causing it to elastically elongate and store strain energy inside. When the tensile displacement reaches the preset value, that is, when the restoring force generated by the skeleton meets the design requirements, a mechanical locking device is used to fix the tooling and maintain the tensile state of the skeleton. The pre-stretched frame, along with the tooling, is placed into the guitar cavity of the guitar that has been assembled. The position is adjusted so that the axis of symmetry of the frame coincides with the center line of the neck, and the two ends are aligned with the predetermined installation points on the inner wall of the side plate. High-toughness structural adhesive is used to firmly bond both ends of the frame to the installation points; Once the adhesive layer has reached sufficient strength, release the locking device of the tooling and remove it from the instrument body. At this time, the metal frame retains the pre-loaded restoring force inside the instrument body. The restoring force generated by the metal skeleton under preload is calculated using the following formula: ; in, The elastic modulus of the metal skeleton material. For the cross-sectional area of ​​the skeleton, The applied axial strain; Axial strain is the displacement applied by the tensioning fixture Compared with the original length of the skeleton Decision, that is ; By precisely controlling displacement , making the restoring force This generates a torque that is opposite to the concave trend of the panel, which partially cancels out the bending moment generated by the chord tension, thereby reducing the net bending moment borne by the panel. It should be noted that the U-shaped frame is made of a high-elasticity-limit lightweight alloy, which combines the advantages of high strength and low density; the special tensioning fixture is equipped with a displacement and force feedback system to achieve precise control of the preloading process; controllable axial tension allows the frame to store stable strain energy; the mechanical locking device maintains the pre-tensioned state until installation is complete; symmetrical positioning ensures the balance of the reverse torque and avoids additional torsion; high-toughness structural adhesive ensures a reliable connection between the frame and the instrument body; after the fixture is released, the frame continues to provide restoring force, forming a stable reverse torque system; this design actively intervenes in the mechanical balance of the instrument body, fundamentally reducing the net bending moment on the panel and improving long-term structural stability.

[0028] S7. The instrument body, which is equipped with a support mesh and metal frame, undergoes overall curing treatment to complete the integrated manufacturing process; Furthermore, the guitar body, with its internal components installed, is then placed smoothly into a curing chamber with controlled temperature and humidity. Adjust the ambient temperature in the curing chamber to a range suitable for the complete curing of the adhesive, while controlling the relative humidity at a suitable level to prevent additional stress on the wood due to swelling and shrinkage. Maintaining the set temperature and humidity conditions for a sufficient time allows the polymer matrix in all adhesive interfaces to complete the full cross-linking reaction, reaching the glass transition temperature and mechanical strength. Avoid sudden temperature changes and airflow disturbances during the curing process; After the curing cycle is completed, the instrument body is removed from the curing chamber. At this time, the connection between the components has reached a long-term stable state, forming a mechanically coordinated and performance-integrated overall structure, which fundamentally prevents the single-panel panel from denting and deforming during long-term use. It should be noted that placing the integrated instrument body into a temperature and humidity-controlled curing chamber provides a consistent curing environment for all adhesive interfaces; precise temperature and humidity control promotes full cross-linking of the adhesive while preventing additional stress caused by the expansion and contraction of the wood due to moisture; sufficient holding time ensures the complete completion of the polymerization reaction; sudden temperature changes and airflow disturbances are avoided to prevent thermal stress or vibration interference from affecting the curing quality; and the connections between the components reach a long-term stable state, forming a mechanically coordinated and performance-unified overall structure.

[0029] In summary, this invention enhances the structural rigidity and deformation resistance of the panel through a biomimetic lightweight support mesh and pre-forming process. Furthermore, it introduces a modular prestressed skeleton to form an active counter-torque, which counteracts the concave tendency caused by string tension from a mechanical perspective. The synergistic effect of each process step achieves superior stability without sacrificing the panel's degree of freedom of vibration. This effectively solves the technical problems of bulky reinforced structures, damaged tone, and poor long-term reliability in traditional processes, extending the guitar's lifespan. At the same time, it optimizes acoustic response characteristics and improves the overall performance and manufacturing precision of the instrument.

[0030] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for manufacturing a solid wood guitar top that prevents denting, characterized in that: include: Finite element stress simulation was performed on a three-dimensional digital model of a single-board guitar top to determine the high-stress areas under stress. Based on the distribution characteristics of high-stress regions, a structural model of a biomimetic support network is generated through topology optimization. Based on the structural model, a lightweight support mesh with a biomimetic structure was fabricated using additive manufacturing technology. The single panel to be processed is placed on a rigid mold with a pre-curved surface, and plastic pre-deformation is carried out by vacuum negative pressure to obtain a pre-formed panel. The lightweight support mesh is fixed to the high-stress area inside the preformed panel. A pre-stressed modular metal frame is installed at a predetermined position inside the instrument body to form a counterforce system that resists the concavity of the panel. The instrument body, which is equipped with a support mesh and metal frame, undergoes an overall curing process to complete integrated manufacturing.

2. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 1, characterized in that: The specific steps for performing finite element stress simulation on the three-dimensional digital model of the single-board guitar top to determine the high-stress areas under stress are as follows: Obtain a three-dimensional geometric model of the top panel of a single-board guitar, wherein the three-dimensional geometric model includes the precise topological structure of the guitar body outline, sound hole boundaries, and neck connection area; Define the anisotropic material properties of the wood used for the panel, including the modulus of elasticity parallel to the grain, the modulus of elasticity across the grain, the shear modulus, and Poisson's ratio; An equivalent total tension of the string is applied at the center of the bridge in the three-dimensional geometric model. The load is directed along the string axis toward the inside of the instrument to simulate the stress conditions during actual performance. Apply full-degree-of-freedom constraints to the connection boundary between the side panels and the back panel of the instrument body; Based on the fundamental equations of linear elastic statics, a set of governing equations is established in the finite element analysis system, where the stress tensor and strain tensor satisfy the generalized Hooke's law, and the displacement field satisfies the equilibrium differential equations. The solution domain is meshed using tetrahedral or hexahedral meshes. Perform statics analysis to obtain the full-field displacement and stress distribution of the structure under load; Extract the Mises equivalent stress distribution cloud map of the front surface of the panel, and identify and mark continuous areas with stress values ​​exceeding a preset threshold as high stress areas.

3. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 2, characterized in that: The specific steps for generating a biomimetic support network structural model based on the distribution characteristics of high-stress regions through topology optimization are as follows: The high-stress region is taken as the design domain, and the material distribution within this region is defined as the optimization variable. An optimization model is established with the goal of minimizing structural mass, and the objective function is the integral of the material volume within the design domain; Structural stiffness constraints are set, requiring that under the same load conditions, the compliance of the optimized structure does not exceed the reference value of the original structure. Compliance is defined as the sum of the products of external load and corresponding displacement. Local stress constraints are introduced, and iterative solutions are performed using a SIMP-based variable density method. By introducing a penalty factor, the intermediate density value is made to approach 0 or 1, thus achieving a clear material distribution. During the iteration process, filtering techniques are used to smooth the design variables; The optimization is considered complete when the rate of change of the objective function and the constraints is lower than the convergence tolerance. The obtained continuous density field is thresholded to generate the geometric contour of the support network; The two-dimensional contour is stretched along the thickness direction and smoothed to construct a three-dimensional support network digital model. Its topology exhibits a hybrid feature of cellular units and truss rods, and the node connections are made with rounded transitions to reduce stress concentration.

4. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 3, characterized in that: The lightweight support mesh with a biomimetic structure is fabricated using additive manufacturing based on a structural model. The specific steps are as follows: The 3D digital model of the supporting network is converted into STL format and imported into additive manufacturing slicing software; Set the printing layer thickness, scanning speed, laser power, and infill path strategy, where the infill path uses contour parallelism or Hilbert curve to ensure structural continuity; A homogeneous mixture of photosensitive resin and short-cut carbon fiber is selected as the printing material. The composite material is cured by free radical polymerization under ultraviolet light irradiation. In stereolithography equipment, a scraper is used to evenly coat the mixed slurry onto the surface of the liquid tank to form a thin layer; The ultraviolet laser beam is controlled to selectively scan according to the cross-sectional data of the current layer, causing the slurry in the irradiated area to cross-link and solidify, forming a solid thin layer; The work platform descends by a preset layer thickness, and the coating and scanning processes are repeated to build up the shape layer by layer. After all layers have been formed, the printed part is peeled off from the substrate and the uncured residual paste is removed using a cleaning solution; The cleaned components are subjected to secondary ultraviolet light irradiation to allow the unreacted functional groups inside to continue cross-linking, thereby achieving the required mechanical properties. After post-processing steps such as removing supports and grinding, a lightweight support mesh with precise geometry and stable physical properties is obtained, in which carbon fibers are oriented along the principal stress path.

5. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 4, characterized in that: The process involves placing the veneer panel to be processed onto a rigid mold with a pre-defined curved surface, and then subjecting it to plastic pre-deformation through vacuum negative pressure to obtain a pre-formed panel. The specific steps are as follows: Prepare a rigid male mold corresponding to the target pre-deformed surface, wherein the mold surface has a calculated micro-convex curvature and its geometry can guide the panel to produce the expected residual deformation. The raw veneer without any internal reinforcement is laid flat on the surface of the male mold; It is covered with a flexible and airtight film, which can stretch with the deformation of the panel without producing wrinkles or local stress concentration. The edges of the film are firmly sealed within the sealing groove of the mold base to form a closed cavity; Start the vacuum pump to extract the air between the film and the mold, so that the air pressure inside the cavity is significantly lower than the external atmospheric pressure, forming a stable negative pressure difference; Under continuous negative pressure, the single board gradually bends and completely fits the mold surface under the pressure difference; Maintaining this bonded state for a period of time allows the wood cell walls to undergo viscoelastic flow and interfiber slippage under continuous stress, thus completing plastic deformation; Slowly release the vacuum, allowing the panel to spring back freely without external force. Due to the incomplete elastic recovery of the wood, the panel retains a stable residual micro-convex shape. The resulting panel is a pre-formed panel, whose initial curvature can effectively counteract the concave trend caused by future string tension, thus preventing deformation from the source.

6. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 5, characterized in that: The specific steps for fixing the lightweight support mesh to the high-stress area inside the preformed panel are as follows: A high-strength two-component epoxy adhesive is formulated, wherein the high-strength two-component epoxy adhesive has good thixotropy, wettability and high shear strength after curing; Apply the adhesive evenly to the entire bottom surface of the lightweight support mesh; The adhesive-coated support mesh is precisely located in the high-stress area inside the preformed panel according to the design coordinates in the three-dimensional digital model. Apply uniform vertical pressure, and use a pressure block or vacuum bag to make the support mesh fully contact the panel surface, squeeze out the air bubbles in the adhesive layer, and form a continuous and dense adhesive interface. Allow the adhesive to stand at room temperature or with moderate heating to undergo the induction, gelation and post-curing stages, so that the molecular chains are fully cross-linked. After the adhesive joint reaches its initial strength, remove the pressure device to complete the fixation of the support mesh. At this point, the support mesh and the panel form a composite load-bearing system to jointly resist external loads.

7. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 6, characterized in that: The specific steps for installing the pre-stressed modular metal frame at a predetermined position inside the instrument body to form a counterforce system against the concavity of the panel are as follows: A U-shaped metal frame is provided, which is made of a lightweight alloy with a high elastic limit and whose free length matches the mounting spacing at the bottom of the instrument's internal cavity. The two ends of the U-shaped metal frame are fixed to the movable clamps of a special tensioning fixture, which is equipped with a displacement measurement and force feedback system. The loading mechanism of the driving tooling applies a controllable axial tensile displacement to the skeleton, causing it to elastically elongate and store strain energy inside. When the tensile displacement reaches the preset value, that is, when the restoring force generated by the skeleton meets the design requirements, a mechanical locking device is used to fix the tooling and maintain the tensile state of the skeleton. The pre-stretched frame, along with the tooling, is placed into the guitar cavity of the guitar that has been assembled. The position is adjusted so that the axis of symmetry of the frame coincides with the center line of the neck, and the two ends are aligned with the predetermined installation points on the inner wall of the side plate. High-toughness structural adhesive is used to firmly bond both ends of the frame to the installation points; Once the adhesive layer has reached sufficient strength, release the locking device of the fixture and remove it from the instrument body. At this point, the metal frame retains the pre-loaded restoring force within the instrument body.

8. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 7, characterized in that: The process of integrally solidifying the instrument body, which is equipped with a support mesh and a metal frame, to complete the integrated manufacturing involves the following steps: The guitar body, with its internal components installed, is then placed smoothly into a curing chamber with controlled temperature and humidity. Adjust the ambient temperature in the curing chamber to a range suitable for the complete curing of the adhesive, while controlling the relative humidity at a suitable level to prevent additional stress on the wood due to swelling and shrinkage. Maintaining the set temperature and humidity conditions for a sufficient time allows the polymer matrix in all adhesive interfaces to complete the full cross-linking reaction, reaching the glass transition temperature and mechanical strength. Avoid sudden temperature changes and airflow disturbances during the curing process; After the curing cycle is completed, the instrument body is removed from the curing chamber. At this point, the connection between the components has reached a long-term stable state, forming a mechanically coordinated and performance-integrated overall structure, which fundamentally prevents the single-panel panel from denting and deforming during long-term use.

9. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 8, characterized in that: The restoring force generated by the metal skeleton under preload is calculated by the following formula: ； in, The elastic modulus of the metal skeleton material. For the cross-sectional area of ​​the skeleton, The applied axial strain; The axial strain is caused by the displacement applied by the tensioning fixture. Compared with the original length of the skeleton Decision, that is ; By precisely controlling displacement , making the restoring force This generates a torque that is opposite to the concave trend of the panel, which partially cancels out the bending moment generated by the chord tension, thereby reducing the net bending moment borne by the panel.

10. The manufacturing method for preventing the top of a solid wood guitar from denting as described in claim 9, characterized in that: The topology optimization process of the supporting network structure model is mathematically composed of an objective function and constraints, including: The objective function is to minimize the material volume within the design domain, and its expression is: ； in, This indicates a design space defined based on high-stress areas. This represents the relative density of the material at each point within the space; Constraints include physical equilibrium equations, stiffness requirements, and strength limitations; Stiffness constraints control the total amount of work done by external forces through structural compliance; Strength constraints are achieved by monitoring the stress of finite element elements, and the Mises equivalent stress of all elements does not exceed the allowable stress of wood. The variable density method combined with a penalty factor is used to discretize and solve the continuum topology optimization problem, and the density field is updated iteratively. This continues until the objective function converges and all constraints are satisfied. The obtained optimal density distribution is thresholded and geometrically reconstructed to generate a three-dimensional support network digital model with well-defined boundaries.

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