Drilling-free assembly process for passenger car

Abstract

The invention provides a drilling-free assembly process for a passenger car, relates to the field of passenger car assembly, and aims to solve the problem that a single and static rigid connection structure adopted between a passenger car interior trim panel and a car body framework is not matched with a complex and dynamic assembly environment at present. The hole position layout can adapt to the temperature difference change in winter and summer, the interior trim panel has enough freedom degree to stretch out and draw back when the temperature changes, the flanging structure formed by the holes in the framework effectively makes up the section inertia moment loss of the pipe, and the smooth flanging forms a blind insertion guide face so that installation can be completed without accurate visual alignment. Clamping stagnation and repeated adjustment are avoided, the problem that blind insertion is difficult is solved, the back face of the interior trim panel is prevented from being scratched by sharp orifices, the guiding and strength problems are solved at the same time through stamping and flanging, the thermal expansion problem is solved in cooperation with data planning, and a flexible drilling-free assembly system low in cost, high in efficiency and high in reliability is constructed.

Description

Technical Field

[0001] This invention relates to the field of bus assembly, and specifically to a bus assembly process that eliminates the need for drilling. Background Technology

[0002] In the traditional assembly of bus interiors, the "on-site measurement and on-site drilling" work mode is commonly used. While this avoids the alignment problems caused by frame welding errors to some extent, it has serious inherent drawbacks. First, it poses high safety and corrosion risks. Blind drilling on-site can easily damage the wiring harnesses embedded inside the body frame, causing potential electrical short circuits. At the same time, if the iron filings generated during drilling are not thoroughly cleaned, they will remain in the frame gaps, leading to rust and corrosion of the body structure due to alternating humidity and heat. Second, it results in low work efficiency and inconsistent quality. This method is highly dependent on the operator's experience, the hole positions are highly arbitrary, and the cumbersome drilling, tapping, or core-pulling riveting processes severely restrict the assembly cycle, making it difficult to meet the needs of modern flexible bus manufacturing.

[0003] To address these issues, existing technologies have begun to explore pre-drilling elongated holes in the frame to achieve drill-free assembly. However, current basic drill-free technologies still have significant limitations. In terms of structural strength, directly drilling elongated holes in a rectangular tube frame without reinforcement reduces the moment of inertia of the tube section, weakening the frame's local load-bearing capacity. Regarding assembly operations, ordinary pre-drilled planar holes lack guiding structures, making alignment difficult when blind insertion is performed with interior trim panels obstructing the view, easily leading to jamming or scratching of the trim panels. In terms of physical performance, the commonly used single-material rigid fasteners have a rigid contact with the metal frame, lacking buffering and sealing media. Vibrations during vehicle operation can easily induce high-frequency noises, and it is difficult to prevent condensation leakage. Furthermore, for long interior trim parts, existing fixing methods fail to adequately consider the differences in material thermal expansion coefficients. During drastic temperature changes between winter and summer, there is a lack of effective space for thermal deformation release, often resulting in arching or tearing of the interior trim panels. In summary, whether it is the traditional on-site drilling process or the existing basic drill-free technology, the existing technologies mostly rely on a single, static, rigid connection structure to cope with the complex dynamic assembly environment full of variables. In terms of process, they cannot adapt to the welding tolerance of the skeleton, and in terms of geometry, they cannot be compatible with the blind insertion operation of workers and the thermal expansion and contraction of materials. Furthermore, they cannot buffer the dynamic vibration of the crane, which affects the assembly efficiency and assembly quality. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a bus assembly process that does not require drilling, which utilizes a stamping and flanging process to form mounting holes with smooth flanges and reinforcing ribs, thereby improving assembly efficiency and quality.

[0005] The first objective of this invention is to provide a drill-free assembly process for passenger vehicles, which employs the following solution: include: Based on the assembly dimension chain and the difference in thermal expansion coefficients of the materials between the interior panels and the body frame, prefabricated holes are planned on the body frame. Mounting holes are obtained by drilling holes at the pre-fabricated holes in the vehicle frame, and a stamping and flanging process is carried out simultaneously to form a smooth flanging that extends into the frame at the edge of the hole. The smooth flanging forms a blind insertion guide surface and a hole perimeter reinforcing rib. Adjust the interior trim to the assembly position, and use the guiding effect of the blind insertion guide surface to press the fasteners into the mounting holes to achieve the connection between the interior trim and the body frame.

[0006] Furthermore, the mounting hole includes a reference positioning hole corresponding to the center of the interior trim part, and an elongated hole extending from the reference positioning hole to both ends with the length increasing with the distance. The elongated hole is a thermal expansion release hole, used to absorb the longitudinal cumulative error generated by the welding of the vehicle body frame.

[0007] Furthermore, when installing the fasteners, first install the fasteners corresponding to the reference positioning holes, and then install the fasteners in sequence in the elongated holes on both sides of the reference positioning holes.

[0008] Furthermore, the fastener includes a rigid toothed body and a soft elastic buffer layer located at the bottom of the umbrella cap. After the fastener engages with the mounting hole, it locks the interior trim and the vehicle body frame. The soft elastic buffer layer is compressed and filled between the interior trim panel and the fastener umbrella cap.

[0009] Furthermore, the interior trim panel has grooves formed at the positions of the pre-drilled holes, and the edges of the grooves have locally thickened protrusions.

[0010] Furthermore, before pressing the fastener into the mounting hole, the fastener is pre-installed into the groove, so that the fastener is in a floating state.

[0011] Furthermore, the area where the soft elastic buffer layer is compressed comprises two parts: the first part is located between the interior panel and the buckle umbrella cap, and the second part extends into the groove to form a seal.

[0012] Furthermore, the smooth flange of the mounting hole forms a transition rounded corner to guide the tip of the fastener into the center of the hole.

[0013] Furthermore, the hard barb body is a multi-layered umbrella-shaped barb structure, and the outer diameter of the barb structure is larger than the inner diameter of the positioning hole after it is flanged.

[0014] Furthermore, the elastic deformation of the barbed structure enables an interference fit with the smooth inner wall of the flange.

[0015] Compared with the prior art, the advantages and positive effects of this invention are: To address the mismatch between the current single, static, rigid connection structure between bus interior panels and the vehicle frame and the complex, dynamic assembly environment, a pre-planned approach based on differences in thermal expansion coefficients ensures that the hole layout can adapt to temperature variations between winter and summer. The interior panels have sufficient freedom to expand and contract with temperature changes. The flanged structure formed by the holes in the frame effectively compensates for the loss of the tubing's cross-sectional moment of inertia, ensuring that the local load-bearing capacity of the vehicle frame does not decrease after the holes are opened. The smooth flange forms a blind insertion guide surface, allowing installation without precise visual alignment. Even if the buckle position has a slight deviation within the guide radius, it can still smoothly slide into the hole, avoiding jamming and repeated adjustments, solving the problem of difficult blind insertion, and preventing sharp holes from scratching the back of the interior panels. The stamped flange simultaneously solves the guidance and strength issues, and combined with data planning, it addresses the thermal expansion problem, constructing a low-cost, high-efficiency, and highly reliable flexible drill-free assembly system. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0017] Figure 1 This is a schematic flowchart of the bus assembly process without drilling in an embodiment of the present invention. Detailed Implementation

[0018] In a typical embodiment of the present invention, such as Figure 1 As shown, a drilling-free assembly process for passenger cars is presented.

[0019] This application provides a drill-free assembly process for passenger vehicles, including: Based on the assembly dimension chain and the difference in thermal expansion coefficients of the materials between the interior panels and the body frame, prefabricated holes are planned on the body frame. Mounting holes are obtained by drilling holes at the pre-fabricated holes in the vehicle frame, and a stamping and flanging process is carried out simultaneously to form a smooth flanging that extends into the frame at the edge of the hole. The smooth flanging forms a blind insertion guide surface and a hole perimeter reinforcing rib. Adjust the interior trim to the assembly position, and use the guiding effect of the blind insertion guide surface to press the fasteners into the mounting holes to achieve the connection between the interior trim and the body frame.

[0020] In practical applications, the planning of prefabricated holes based on the assembly dimension chain between the interior trim panel and the vehicle body frame, as well as the difference in the coefficients of thermal expansion of the materials, determines the specific distribution of the holes based on the geometric relationship between the interior trim panel and the vehicle body frame, and the expansion characteristics of the materials under different temperature conditions. For example, finite element analysis can be used to simulate the deformation behavior of materials under extreme temperature conditions, thereby optimizing the hole layout to adapt to dimensional changes caused by thermal expansion. The main purpose is to achieve proactive adaptability of the hole design to the thermal expansion effect and avoid assembly failures caused by temperature differences.

[0021] Drilling holes at pre-fabricated locations on the vehicle body frame and simultaneously performing a stamping and flanging process can be achieved in various ways. For example, the flanging can be performed simultaneously with the drilling using a CNC punch press, or the required geometry can be formed at the edge of the hole using hydroforming equipment. Smooth flanging can employ an arc-shaped transition structure or a gradient curvature design to ensure effective guidance of the fastener into the center of the hole during blind insertion. Furthermore, the flanging functions as a reinforcing rib around the hole; its height or thickness can be increased to further strengthen the local structural strength, thereby offsetting the impact of the drilling on the frame's load-bearing capacity.

[0022] After the interior trim parts are positioned for assembly, the fasteners are pressed into the mounting holes using the guiding action of the blind-fit guide surface. This process can be completed manually by workers or by automated equipment. For example, a pneumatic riveting tool can be used to quickly press the fasteners into the holes, or a robotic arm can be used for precise positioning and pressing. The blind-fit guide surface can be designed with an inclined or tapered surface structure to reduce the difficulty of aligning the fasteners during insertion, thereby improving assembly efficiency.

[0023] By integrating design and manufacturing processes, this approach systematically addresses the safety hazards and efficiency issues inherent in traditional assembly methods, and overcomes the structural deficiencies of existing drill-free technologies. First, prefabricated hole positions are planned based on the assembly dimension chain and differences in material thermal expansion coefficients, enabling proactive adaptation of the hole layout to thermal expansion effects and overcoming the lack of a thermal deformation release mechanism in existing technologies. Second, the simultaneous implementation of a stamping and flanging process creates smooth flanges, providing precise guidance for blind insertion operations and strengthening the local structural integrity of the skeleton, thus resolving the reduced load-bearing capacity caused by the lack of reinforcement in existing elongated holes. Finally, the guiding mechanism formed by the flanging enables rapid positioning and connection of fasteners, fundamentally avoiding the risks of wire harness damage and metal shavings residue, while significantly improving assembly efficiency and quality consistency.

[0024] Based on the assembly dimension chain and the difference in thermal expansion coefficients between the interior trim panels and the vehicle body frame, pre-fabricated holes are planned on the vehicle body frame. This process fully considers the dynamic deformation characteristics of materials under temperature changes, enabling the hole layout to actively adapt to dimensional fluctuations caused by thermal expansion. This avoids the arching or tearing of the interior trim panels due to temperature differences between winter and summer, and solves the problem of the lack of a thermal deformation release mechanism in existing technologies.

[0025] Mounting holes are created by drilling pre-drilled holes in the vehicle body frame, and a stamping and flanging process is simultaneously implemented to form a smooth flanged edge extending inwards from the edge of the hole towards the frame. This simultaneous process ensures the geometric consistency between the flanged edge and the hole position. The smooth flanged edge serves as a guide surface for blind insertion, effectively guiding the fastener to slide smoothly into the center of the hole even when visibility is obstructed, significantly reducing the risk of jamming during blind insertion and the probability of scratching the interior panels. At the same time, the flanged edge acts as a reinforcing rib around the hole, strengthening the local cross-sectional stiffness of the frame, offsetting the weakening effect of the hole on structural strength, and overcoming the defect of reduced load-bearing capacity caused by the lack of reinforcement in existing long holes.

[0026] After the interior trim parts are positioned for assembly, the guide surface of the blind-fitting guide is used to press the fasteners into the mounting holes, thus connecting the interior trim parts to the vehicle body frame. The precise guiding mechanism created by the flange enables rapid positioning and connection, eliminating the need for on-site drilling and fundamentally avoiding the risks of wire harness damage and metal shavings residue. At the same time, the simplified blind-fitting operation significantly improves assembly cycle time and quality consistency, effectively addressing the inefficiencies and quality fluctuations caused by reliance on manual experience in traditional processes.

[0027] The bus assembly process without drilling not only solves the problems of wire harness damage, iron filings corrosion risk and low assembly efficiency caused by on-site drilling in bus interior assembly, but also overcomes the defects of existing drilling-free technologies, such as insufficient structural strength due to lack of reinforcement for long holes, difficulty in blind insertion operation and poor adaptability to thermal expansion.

[0028] The mounting holes include a reference positioning hole corresponding to the center of the interior trim part, and an elongated hole extending from the reference positioning hole to both ends with the length increasing with the distance. The elongated hole is a thermal expansion release hole, used to absorb the longitudinal cumulative error generated by the welding of the body frame.

[0029] Specifically, a reference hole is a fixed hole located at the center of an interior trim component. It serves as a reference point during assembly, ensuring the accuracy and stability of the initial positioning of the trim component. In practical applications, reference holes can be positioned and drilled using machining equipment to guarantee their geometric accuracy and assembly reliability. The length of different elongated holes increases with distance from the reference hole, allowing for greater flexibility at locations further away to accommodate deformation caused by differences in material thermal expansion coefficients and temperature changes. The design purpose of these elongated holes is to compensate for manufacturing tolerances and thermal stress through an elastic release mechanism, preventing warping or tearing of the interior trim panel.

[0030] The optimized layout of the mounting holes enables adaptive management of thermal deformation and errors. The reference positioning holes, serving as the core datum points for assembly, first ensure the initial alignment accuracy between the interior trim parts and the body frame, providing a reliable positioning foundation for subsequent operations. Furthermore, the elongated holes effectively absorb longitudinal cumulative errors generated during the welding process of the body frame and provide sufficient space for thermal expansion release during temperature changes, preventing damage to the interior trim panels due to thermal stress. In addition, the gradually increasing length design of the elongated holes enhances the release capacity further away from the center area, better adapting to the assembly requirements of long interior trim parts. This structural design, combined with the smooth flanging process on the body frame, further improves assembly efficiency and connection reliability, while solving the problem that traditional rigid connection methods struggle to cope with complex dynamic assembly environments.

[0031] When installing the fasteners, first install the fasteners corresponding to the reference positioning holes, and then install the fasteners in sequence through the elongated holes on both sides of the reference positioning holes. By using the reference positioning holes and the elongated holes in conjunction with a specific fastener installation sequence, precise assembly of the interior trim parts is achieved. First, the fasteners corresponding to the reference positioning holes are installed first, locking the center position of the interior trim parts, thus providing a stable reference for subsequent assembly. Based on this, the fasteners in the elongated holes on both sides of the reference positioning holes are installed sequentially from the inside out. This allows the elongated holes to gradually expand their fixing range while absorbing welding errors and thermal expansion deformation, thereby ensuring that the interior trim parts remain evenly distributed and stably connected throughout the assembly process. Furthermore, the combination of the elongated holes and the fastener installation sequence effectively solves the problem of overall misalignment caused by accumulated errors, while improving assembly efficiency and accuracy.

[0032] The fastener consists of a rigid toothed body and a soft, elastic buffer layer located at the bottom of the umbrella cap. After the fastener is fitted with the mounting hole, it locks the interior trim and the body frame together. The soft, elastic buffer layer is compressed and filled between the interior trim panel and the fastener umbrella cap.

[0033] Specifically, the rigid countersunk tooth body ensures a secure lock after the fastener mates with the mounting holes, providing a stable mechanical connection base; the soft elastic buffer layer is a material layer with a certain degree of elasticity and softness, which can be made of materials such as rubber or silicone, and can absorb vehicle vibration energy to reduce the transmission of high-frequency abnormal noises, while forming a sealing layer to prevent condensation from seeping in.

[0034] In the bus assembly process without drilling, the fasteners achieve a secure lock by engaging with the mounting holes using a rigid, toothed body, thus reliably connecting the interior trim to the vehicle frame. The soft, elastic buffer layer at the bottom of the umbrella-shaped vent is compressed after the fastener is pressed into the mounting hole, filling the gap between the interior trim panel and the fastener vent. The rigid body provides a stable mechanical connection, while the soft buffer layer provides dynamic cushioning and static sealing. This combination not only avoids the defects of rigid contact but also effectively solves the problem of high-frequency noises during vehicle operation and achieves effective sealing against condensation.

[0035] The interior trim panel features grooves corresponding to pre-drilled holes, with locally thickened protrusions along the edges of these grooves. The grooves are strip-shaped recesses machined into the interior trim panel at the locations corresponding to the pre-drilled holes, and can be achieved through stamping, injection molding, or machining. These grooves provide floating space and precise positioning for the fasteners, facilitating alignment with the mounting holes during blind insertion and reducing the risk of scratches. The locally thickened protrusions are structures that increase material thickness at the edges of the grooves. These can be achieved through integral molding or subsequent welding reinforcement, enhancing the structural strength of the groove edges, preventing deformation or damage during installation, and ensuring smooth sliding of the fasteners.

[0036] Before pressing the fastener into the mounting hole, pre-install the fastener into the groove, allowing it to float. In practical applications, this step can be done manually or with the help of automated equipment, providing precise initial positioning for the subsequent pressing action and thus reducing assembly difficulty.

[0037] In the no-drill assembly process for buses, a pre-installation platform for fasteners is first provided by a sliding groove structure, allowing workers to quickly and accurately place the fasteners in the predetermined positions. Furthermore, the floating state of the fasteners within the groove enables them to automatically adjust. During blind insertion, the fasteners can self-adjust according to the actual position of the mounting hole, effectively avoiding jamming or scratches caused by positional deviations. The combination of the pre-installation mechanism and the sliding groove structure not only improves assembly accuracy but also significantly increases assembly efficiency. Simultaneously, this solution, in conjunction with the smooth flanges on the vehicle body frame and the locally thickened bosses on the interior panels, constitutes a complete assembly system, solving the alignment problem in blind insertion operations and ensuring a smooth assembly process.

[0038] The compressed area of ​​the soft, elastic cushioning layer comprises two parts: the first part is located between the interior trim panel and the buckle cap, and the second part extends into the groove to form a seal. During actual assembly, when the buckle is pressed into the mounting hole, the first part of the soft, elastic cushioning layer is compressed first, ensuring tight contact between the interior trim panel and the buckle cap, thus inheriting the original cushioning function. Simultaneously, the second part of the soft, elastic cushioning layer extends into the groove, directly filling the gaps in the groove area, forming a continuous sealing barrier, effectively preventing condensation leakage, and also improving overall sealing performance.

[0039] The smooth flange of the mounting hole forms a transition fillet to guide the pin tip into the center of the hole. The transition fillet is an arc-shaped transition area formed at the junction of the smooth flange and the hole opening, which can be achieved using arc surfaces with different radii of curvature. In practical applications, the transition fillet provides a smoother entry transition, allowing the pin tip to naturally guide to the center of the hole, avoiding misalignment or jamming.

[0040] As the fastener approaches the mounting hole, the rounded corner first contacts the tip of the fastener and gradually guides it to the center of the hole, ensuring smooth entry of the fastener, significantly reducing assembly resistance and preventing component damage. Simultaneously, this process, combined with the smooth flange and blind insertion guide surface, improves assembly efficiency while ensuring reliability, effectively solving potential jamming or misalignment issues during fastener assembly and enhancing overall assembly quality and efficiency.

[0041] The rigid barb body features a multi-layered umbrella-shaped barb structure, with the outer diameter of the barb structure larger than the inner diameter of the positioning hole after flangering. The rigid barb body can be made of rigid plastic, with multiple layers of umbrella-shaped barbs formed through injection molding. This increases the number and density of engagement points, thereby enhancing the locking force between the fastener and the mounting hole. The multi-layered umbrella-shaped barb structure design ensures elastic deformation during installation, achieving a reliable interference fit. The outer diameter of the barb structure being larger than the inner diameter of the positioning hole after flangering allows the barb to undergo moderate elastic compression when entering the mounting hole, thus returning to its original shape after passing through the hole, forming a strong locking effect.

[0042] The barbed structure achieves an interference fit with the inner wall of the smooth flange through elastic deformation. The barbed structure provides sufficient elastic deformation capacity to smoothly slide into the mounting hole during installation, while ensuring that it recovers its shape after deformation to form a tight fit. Specifically, when the rigid barbed body is pressed into the mounting hole, its multi-layered umbrella-shaped barb structure undergoes elastic deformation, causing the barbs to contract inwards as they enter the hole, thereby reducing installation resistance. Once the barbs have completely passed through the smooth flange, due to their elastic recovery characteristics, they open outwards and form an interference fit with the inner wall of the flange. This not only ensures a strong connection but also absorbs vibrations from vehicle operation through elastic deformation, effectively preventing loosening and abnormal noises caused by vibration. Furthermore, the soft elastic buffer layer is compressed during the fastener installation process, and its extension into the groove forms a reliable seal to prevent condensation leakage.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A drill-free assembly process for passenger vehicles, characterized in that, include: Based on the assembly dimension chain and the difference in thermal expansion coefficients of the materials between the interior panels and the body frame, prefabricated holes are planned on the body frame. Mounting holes are obtained by drilling holes at the pre-fabricated holes in the vehicle frame, and a stamping and flanging process is carried out simultaneously to form a smooth flanging that extends into the frame at the edge of the hole. The smooth flanging forms a blind insertion guide surface and a hole perimeter reinforcing rib. Adjust the interior trim to the assembly position, and use the guiding effect of the blind insertion guide surface to press the fasteners into the mounting holes to achieve the connection between the interior trim and the body frame.

2. The bus assembly process without drilling as described in claim 1, characterized in that, The mounting holes include a reference positioning hole corresponding to the center of the interior trim part, and an elongated hole extending from the reference positioning hole to both ends with the length increasing with the distance. The elongated hole is a thermal expansion release hole, used to absorb the longitudinal cumulative error generated by welding the body frame.

3. The bus assembly process without drilling as described in claim 2, characterized in that, When installing the fasteners, first install the fasteners corresponding to the reference positioning holes, and then install the fasteners in sequence through the elongated holes on both sides of the reference positioning holes.

4. The bus assembly process without drilling as described in claim 1, characterized in that, The fastener includes a rigid toothed body and a soft elastic buffer layer located at the bottom of the umbrella cap. After the fastener is engaged with the mounting hole, it locks the interior trim and the vehicle body frame. The soft elastic buffer layer is compressed and filled between the interior trim panel and the fastener umbrella cap.

5. The bus assembly process without drilling as described in claim 4, characterized in that, The interior trim panel has grooves formed at the positions of the pre-drilled holes, and the edges of the grooves are formed with locally thickened protrusions.

6. The bus assembly process without drilling as described in claim 5, characterized in that, Before pressing the fastener into the mounting hole, pre-install the fastener into the groove so that the fastener is in a floating state.

7. The bus assembly process without drilling as described in claim 5 or 6, characterized in that, The compressed area of ​​the soft, elastic buffer layer comprises two parts: the first part is located between the interior panel and the buckle umbrella cap, and the second part extends into the groove to form a seal.

8. The bus assembly process without drilling as described in claim 4, 5, or 6, characterized in that, The smooth flange of the mounting hole forms a transition rounded corner to guide the tip of the fastener into the center of the hole.

9. The bus assembly process without drilling as described in claim 8, characterized in that, The hard barb body is a multi-layered umbrella-shaped barb structure, and the outer diameter of the barb structure is larger than the inner diameter of the positioning hole after it is flanged.

10. The bus assembly process without drilling as described in claim 9, characterized in that, The barbed structure achieves an interference fit with the smooth inner wall of the flange through elastic deformation.

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