Carbon fiber composite case structure of acoustic electronic equipment and manufacturing method thereof

Abstract

The application discloses a kind of carbon fiber composite machine case structure of acoustic electronic equipment and manufacturing method thereof.The cabinet includes integrally molded side plate and top plate, which is carbon fiber-glass steel-carbon fiber sandwich structure, total wall thickness ≥8mm;Embedded in the sandwich with barbed aluminum alloy thread column, fixed by mold clamping, and with carbon fiber skin through conductive silver glue or tinning realizes electrical communication;Front panel contains 15mm aluminum alloy inner framework, 6mm outside protrusion forms installation step, and is equipped with 12 / 6mm thick carbon fiber outer frame, inner framework and outer frame are connected with embedded column and framework screw respectively;Bottom plate and back plate are aluminum alloy, and form hybrid structure with carbon fiber parts;Overall carbon fiber skin connects metal screw joint and conductive treatment to form electromagnetic shielding cage.The application is suitable for decoder, frequency divider, power amplifier and other acoustic equipment, compared with aluminum alloy cabinet, wallboard vibration is reduced by 25dB, signal-to-noise ratio is improved by more than 5dB, embedded part is not loose after-20°C to +80°C cycle 200 times, torque decay is less than 5%.

Description

Technical Field

[0001] This invention relates to the field of audio electronic equipment, and more particularly to a carbon fiber composite chassis structure for audio electronic equipment and its manufacturing method. Background Technology

[0002] The chassis of existing audio electronic equipment (such as preamplifiers, decoders, phono amplifiers, crossovers, power amplifiers, and excitation power supplies) are generally made of aluminum alloy profiles or thin steel plates. While these metal chassis offer good electromagnetic shielding and ease of manufacturing, they have inherent drawbacks in the following aspects:

[0003] 1. Microphonic Effect: Aluminum alloys have a low elastic modulus (about 70 GPa) and a wall thickness of only 1.5–2 mm. This makes the chassis wall panel prone to vibration under the magnetostriction of the internal transformer and external acoustic excitation, causing microphonic noise modulation in connectors, capacitors, and PCB boards, thus degrading the signal-to-noise ratio.

[0004] 2. Thermal expansion mismatch: The coefficient of thermal expansion of aluminum alloys is approximately 23 × 10⁻⁻⁻⁶. 6 / ℃) and internal PCB substrate (FR-4 approx. 14×10⁻ 6 The differences between the temperature (°C) and the crystal oscillator cause slight changes in the contact resistance of the connector and drift of the crystal oscillator frequency during temperature cycling.

[0005] 3. Structural assembly gaps: The splicing of aluminum alloy profiles relies on a large number of screws and corner brackets, resulting in assembly gaps. After long-term thermal cycling and transportation vibration, these gaps are prone to loosening, causing structural noise.

[0006] In recent years, some high-end audio products have begun to use carbon fiber as the chassis material. However, the existing technology is mostly a single-layer carbon fiber skin or thin-walled decorative parts, which mainly serve the purpose of weight reduction or aesthetic enhancement, but have not solved the comprehensive needs of load-bearing, vibration reduction, electromagnetic shielding and long-term reliability. Summary of the Invention

[0007] The purpose of this invention is to provide a carbon fiber composite chassis structure for audio electronic equipment and its manufacturing method, so as to solve the problems of significant micro-noise effect, thermal expansion mismatch and insufficient long-term reliability of existing aluminum alloy chassis.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A chassis structure for audio electronic equipment includes side panels and a top panel integrally molded from carbon fiber composite material. The side panels and top panel are a carbon fiber-fiberglass-carbon fiber sandwich structure, with the core material being randomly selected chopped strand mat fiberglass and a total wall thickness ≥8mm. The sandwich structure contains embedded aluminum alloy threaded posts with anti-rotation barbs. These aluminum alloy threaded posts are fixed during the integral molding process by mechanical locking within the mold, and are electrically connected to the carbon fiber outer skin through conductive silver paste or tin plating. The front panel includes a 15mm thick... The aluminum alloy inner frame has an outer edge that protrudes 6mm to form a step for mounting knobs or interfaces, and a carbon fiber outer frame with an edge thickness of 12mm and a panel thickness of 6mm. The aluminum alloy inner frame is connected to the pre-embedded aluminum alloy threaded post screws, and the carbon fiber outer frame is fixed to the outer surface of the aluminum alloy inner frame by screws. The bottom plate and back plate are both aluminum alloy plates, forming a mixed structure of different materials with the carbon fiber composite side plates / top plates. The interior of the chassis forms an electromagnetic shielding cage composed of an integral carbon fiber skin, metal screw nodes, and conductive treatment.

[0009] Preferably, the total wall thickness is 10mm, wherein the outer carbon fiber skin consists of 6 layers of prepreg and the core material is 4mm of random chopped strand mat fiberglass.

[0010] A method for manufacturing an audio electronic equipment chassis includes the following steps: S1: Preparation of carbon fiber prepreg - random chopped strand mat fiberglass - carbon fiber prepreg layup; S2: An aluminum alloy threaded column with anti-rotation barbs is fixed in the mold by mechanical positioning; S3: The ply and aluminum alloy threaded column are integrally molded to obtain the side plate and top plate; S4: Coat the contact surface between the aluminum alloy threaded post and the carbon fiber skin with conductive silver paste or tin plating. S5: Fix the 15mm aluminum alloy front panel inner frame to the aluminum alloy threaded post; S6: Fix the carbon fiber outer frame with an edge thickness of 12mm and a panel thickness of 6mm to the aluminum alloy inner skeleton.

[0011] Preferably, the conductive treatment is coating with conductive silver paste or tin plating. Beneficial effects

[0012] Compared with the prior art, the present invention has the following unexpected technical effects:

[0013] 1. Significantly Improved Structural and Acoustic Performance: Utilizing a 10mm carbon fiber-fiberglass-carbon fiber sandwich frame, the chassis wall vibration velocity is reduced by 25dB compared to a traditional 2mm aluminum alloy chassis. When the same audio electronic circuit board is installed in both the present invention's chassis and a traditional aluminum alloy chassis, the output signal-to-noise ratio is improved by more than 5dB, significantly suppressing secondary radiation from the chassis walls caused by transformers and external sound waves. This effect is not an inherent property of the carbon fiber material itself, but rather a synergistic effect of the sandwich structure, the pre-embedded anchoring method, and the overall composite front panel structure.

[0014] 2. Reliable electromagnetic shielding performance: Through the integrally connected carbon fiber skin, pre-embedded aluminum alloy threaded posts and conductive silver paste / tin-plated nodes, a continuous electromagnetic shielding cage is formed, which achieves the expected shielding performance in the 100MHz–1GHz frequency band without the need for additional independent metal shielding covers.

[0015] 3. Excellent long-term structural reliability: After 200 cycles at temperatures ranging from -20°C to +80°C, the embedded parts showed no loosening, and the screw torque attenuation was less than 5%. The low interlaminar shear strength of carbon fiber laminates and the interface failure of embedded parts in thick-walled sandwich structures under long-term thermal cycling are known engineering challenges. This invention solves this problem through a specific structure combining aluminum alloy threaded posts with anti-rotation barbs with mechanical clamping of the mold.

[0016] 4. Functional Zoning and Asymmetrical Hybrid Structure: The carbon fiber sandwich frame provides load-bearing, vibration damping, and shielding; the aluminum alloy base / back plate serves as the mounting and heat dissipation interface for electronic components; the aluminum alloy inner frame of the front panel supports knobs / interfaces and provides a precise mounting reference; and the carbon fiber outer frame maintains aesthetic consistency, achieving a separation and integration of structural function and aesthetic function. This invention is applicable to all audio electronic equipment such as preamplifiers, decoders, phono amplifiers, crossovers, power amplifiers, and excitation power supplies. Attached Figure Description

[0017] Figure 1 This is an exploded view of the overall structure of the chassis of the present invention; Figure 2 Partial cross-section of the side / top plate sandwich structure; Figure 3 Enlarged view of the pre-embedded aluminum alloy threaded column structure; Figure 4 This is a partial cross-section of the front panel composite structure; Figure 5 This is a schematic diagram illustrating the principle of electromagnetic shielding. Figure 6 This is a partial cross-section showing the connection between the base plate and the integrated frame. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0019] Example 1: Audio Electronic Equipment Chassis like Figure 1 As shown, the audio electronic equipment chassis of this embodiment includes an integrated frame (1) for the side and top panels, an aluminum alloy inner frame (2) for the front panel, a carbon fiber outer frame (3) for the front panel, an aluminum alloy bottom plate (4) and an aluminum alloy back plate (5). This embodiment is applicable to all audio electronic equipment such as preamplifiers, decoders, phono amplifiers, crossovers, power amplifiers, and excitation power supplies.

[0020] like Figure 2 As shown, the integrated frame (1) of the side panel and top panel is a carbon fiber-fiberglass-carbon fiber sandwich structure with a total wall thickness of 10mm. The outer carbon fiber skin (10) is a 6-layer carbon fiber prepreg with a thickness of about 2mm; the inner carbon fiber skin (12) is also a 6-layer carbon fiber prepreg with a thickness of about 2mm; the core material (11) is 4mm of random chopped strand mat fiberglass, which is composed of epoxy resin and random chopped strand mat. This sandwich structure is integrally molded, and the outer skin (10) and the inner skin (12) form a whole with the core material (11) during the molding process.

[0021] like Figure 3 As shown, before molding, the aluminum alloy threaded post (20) with anti-rotation barbs (21) is fixed in a predetermined position through the mechanical locking groove (22) in the mold. After molding, the aluminum alloy threaded post (20) is clamped in the fiberglass core material (25) by the outer carbon fiber skin (23) and the inner carbon fiber skin (24). Conductive silver paste or tin plating is applied to the contact surface between the aluminum alloy threaded post (20) and the carbon fiber skin (26) to form a low-resistance electrical connection.

[0022] like Figure 4 As shown, the front panel includes a 15mm thick aluminum alloy inner frame (30), with its outer edge protruding 6mm to form a mounting step (31) for mounting knobs or interfaces (35). The aluminum alloy inner frame (30) is fixed to a pre-embedded aluminum alloy threaded post by screws (34). The carbon fiber outer frame includes an edge portion (32, 12mm thick) and a panel portion (33, 6mm thick), which are fixed to the outer surface of the aluminum alloy inner frame (30) by screws (34).

[0023] like Figure 6 As shown, the aluminum alloy base plate (51) is connected to the pre-embedded threaded post on the edge (50) of the integrated frame by fixing screws (52), and is supplemented by edge connection flange (53) if necessary. Foot pad mounting positions are reserved on the base plate (51).

[0024] like Figure 5As shown, the electromagnetic shielding cage of the entire machine is composed of the following path: the carbon fiber skin (40) of the side plate / top plate is connected as a whole → the pre-embedded aluminum alloy threaded column (41) → the conductive treatment node (42, silver paste / tin plating) → the aluminum alloy base plate (43) / aluminum alloy back plate (44) → the aluminum alloy inner skeleton of the front panel (45) → the carbon fiber outer frame of the front panel (46) → the screw connection node (47). This continuous conductive path forms a Faraday cage, which shields the electromagnetic radiation generated by the internal PCB and transformer, while suppressing external radio frequency interference. Experimental data

[0025] Experiment 1 (Vibration Comparison): The same audio electronic equipment circuit board was installed in both a traditional 2mm aluminum alloy chassis and the chassis of this embodiment. The internal transformer was run at full load, and the vibration velocity of the wall panel was measured using a laser vibrometer. The vibration velocity of the chassis wall panel in this embodiment was 25dB lower than that of the aluminum alloy chassis.

[0026] Experiment 2 (Electromagnetic Shielding): The shielding effectiveness was tested in the 100MHz–1GHz frequency band according to the GB / T 12190 standard. The chassis in this embodiment meets the electromagnetic compatibility requirements of audio electronic equipment.

[0027] Experiment 3 (Temperature Cycling Reliability): The chassis of this embodiment was placed in an environmental chamber ranging from -20°C to +80°C for 200 cycles, with each cycle lasting 30 minutes. After the cycles, the pull-out force of the embedded parts and the torque of the screws were tested. The embedded parts were not loose, and the torque decay was less than 5%.

[0028] Experiment 4 (Signal-to-Noise Ratio): The same audio electronic equipment circuit board was installed in both a traditional aluminum alloy chassis and the chassis of this embodiment. The output noise was measured using an Audio Precision analyzer. The signal-to-noise ratio of the chassis of this embodiment is more than 5dB higher than that of the aluminum alloy chassis.

Claims

1. A chassis structure for audio electronic equipment, comprising a side panel and a top panel integrally molded from carbon fiber composite material, characterized in that: The side plate and top plate are carbon fiber-fiberglass-carbon fiber sandwich structure, with the core material being random chopped strand mat fiberglass, and the total wall thickness being ≥8mm. The sandwich structure has an embedded aluminum alloy threaded post with anti-rotation barbs. The aluminum alloy threaded post is fixed by mechanical positioning in the mold during the integral molding process, and the aluminum alloy threaded post and the carbon fiber skin are electrically connected by conductive silver paste or tin plating. The front panel includes an aluminum alloy inner frame with a thickness of 15mm, the outer edge of which protrudes 6mm to form a step for mounting knobs or interfaces, and a carbon fiber outer frame with an edge thickness of 12mm and a panel thickness of 6mm. The aluminum alloy inner frame is connected to the pre-embedded aluminum alloy threaded post screws, and the carbon fiber outer frame is fixed to the outer surface of the aluminum alloy inner frame by screws. Both the bottom plate and the back plate are made of aluminum alloy, forming a mixed structure of different materials with the carbon fiber composite side plates / top plates; The interior of the chassis forms an electromagnetic shielding cage composed of an integral carbon fiber skin, metal screw nodes, and conductive treatment.

2. The chassis structure according to claim 1, characterized in that: The total wall thickness is 10mm, with each outer carbon fiber skin consisting of 6 layers of prepreg and the core material being 4mm of random chopped strand mat fiberglass.

3. A method for manufacturing an audio electronic equipment chassis, characterized in that, Includes the following steps: S1: Preparation of carbon fiber prepreg - random chopped strand mat fiberglass - carbon fiber prepreg layup; S2: An aluminum alloy threaded column with anti-rotation barbs is fixed in the mold by mechanical positioning; S3: The ply and aluminum alloy threaded column are integrally molded to obtain the side plate and top plate; S4: Coat the contact surface between the aluminum alloy threaded post and the carbon fiber skin with conductive silver paste or tin plating. S5: Fix the 15mm aluminum alloy front panel inner frame to the aluminum alloy threaded post; S6: Fix the carbon fiber outer frame with an edge thickness of 12mm and a panel thickness of 6mm to the aluminum alloy inner skeleton.

4. The manufacturing method according to claim 3, characterized in that: The conductive treatment is to coat the surface with conductive silver paste or to plate it with tin.

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