Method for eliminating polishing marks on vehicle paint finishes

Abstract

This invention relates to the field of vehicle body painting technology, specifically providing a polishing method for eliminating polishing marks on vehicle paint surfaces, aiming to solve the problems of large quality fluctuations and missed detection of hidden defects in existing manual paint polishing methods. To this end, the polishing method of this invention includes the following steps: pre-treating the vehicle paint surface; performing fixed-point rough polishing on the paint surface using an eccentric polishing machine; and performing circular fine polishing on the paint surface using the same eccentric polishing machine. This polishing method uses a standardized, segmented polishing process with an eccentric polishing machine to address paint surface defects. A single complete polishing operation is divided into two fixed processes, with the total operation time strictly locked at 12-15 seconds. The entire process, including actions, duration, and speed, is standardized. Through this quantitative process of fixed speed, fixed duration, and fixed actions, it completely eliminates reliance on manual experience, allowing new employees to quickly learn and achieve standardized operation, and completely eliminating paint quality fluctuations caused by differences in personnel skills.

Description

Technical Field

[0001] This invention relates to the field of vehicle body painting technology, specifically providing a polishing method for eliminating polishing marks on vehicle paint surfaces. Background Technology

[0002] Polishing and finishing the vehicle body paint is a crucial post-processing step in the mass production of vehicle painting. After the topcoat has cured, appearance defects such as raised particles and localized runs that occurred during the painting process typically need to be repaired through polishing. The quality of the polishing operation directly affects the overall vehicle appearance acceptance level and the final delivery quality.

[0003] Currently, mass production painting workshops in the industry generally use 3200RPM concentric polishing machines in conjunction with traditional manual polishing processes. However, this process has gradually revealed technical shortcomings in multiple dimensions, including equipment, processes, and testing, making it difficult to meet the high-quality, flawless delivery standards for high-end vehicle paint finishes. Specific technical deficiencies are as follows:

[0004] 1. Traditional polishing equipment has inherent hardware defects.

[0005] Traditional 3200RPM concentric polishing equipment has limited cutting power, and the abrasive maintains a fixed-point, one-sided friction with the paint surface for extended periods. This results in poor smoothing and removal of deep scratches and grooves, hindering the improvement of first-pass polishing yield. Furthermore, the coaxial, fixed-point rotation of concentric polishing machines easily leads to localized heat accumulation. Conventional solid polishing cotton lacks a heat dissipation structure, preventing timely heat dissipation and easily causing micro-burns to the clear coat layer, resulting in large areas of polishing haze after polishing. Existing equipment cannot simultaneously remove deep scratches and suppress haze; defect rectification often requires multiple polishing passes, further increasing the risk of paint damage.

[0006] 2. Lack of a standardized system for polishing processes.

[0007] Currently, the polishing industry lacks unified and quantifiable standardized operating procedures. Key operational parameters such as polishing trajectory, operation time, and polishing force rely entirely on the individual experience of technicians. Existing technological optimizations mostly focus on improving single consumables, lacking an integrated solution that combines equipment parameter matching, segmented time control, standardized operation, and quality control. Variations in manual operation lead to significant fluctuations in polishing scratches and haze defects on the entire vehicle's paint surface, making it impossible to achieve stable source control of polishing defects.

[0008] According to mass production defect data statistics, polishing scratches on large flat covering parts such as the hood and tailgate account for 59% of the total number of polishing defects in the whole vehicle, making them high-incidence areas for polishing defects. Among all polishing defects, sanding scratches account for 91.4% and polishing haze accounts for 8.6%. Trace defects are the main stubborn problems in the painting and polishing process.

[0009] 3. There are obvious shortcomings in the methods for detecting paint defects.

[0010] Current paint quality inspection mainly relies on visual inspection under natural light. However, defects such as subtle, hidden scratches caused by polishing and high-temperature-induced haze are difficult to effectively identify under natural light conditions. A large number of hidden defects flow into subsequent processes or the end market, and appearance flaws will be exposed shortly after vehicle delivery, leading to after-sales repairs and customer complaints, significantly increasing the overall vehicle after-sales maintenance costs. Summary of the Invention

[0011] The present invention aims to solve the above-mentioned technical problems, namely, to solve the problems of large quality fluctuations and missed detection of hidden defects in existing manual polishing methods for paint surfaces.

[0012] This invention provides a polishing method for eliminating polishing marks on vehicle paint surfaces. The polishing method includes the following steps: pre-treating the paint surface of the vehicle; performing point-to-point coarse polishing on the paint surface using an eccentric polishing machine; and performing circular fine polishing on the paint surface using the eccentric polishing machine.

[0013] Furthermore, the pretreatment step of the paint surface includes: assembling fine wet sandpaper onto the sanding end of the sander; wet sanding and smoothing out the raised defects on the paint surface, and sanding evenly.

[0014] Furthermore, the eccentric polishing machine is equipped with an eccentric rotating shaft with an eccentric distance of 12mm; the output end of the eccentric rotating shaft is equipped with a non-porous hard polishing disc; polishing cotton with distributed ventilation micropores is attached and installed on the non-porous hard polishing disc.

[0015] Furthermore, the step of performing fixed-point rough polishing on the paint surface includes: starting the eccentric polishing machine, vertically and tightly adhering the polishing cotton to all the polishing points of the paint surface; maintaining the eccentric polishing machine at a set speed, and performing fixed-point polishing on the paint surface for a first set time.

[0016] Furthermore, the first set duration is 5 to 6 seconds; the set rotation speed is 5000 RPM.

[0017] Furthermore, the step of using the eccentric polishing machine to perform circular fine polishing on the paint surface includes: the eccentric polishing machine maintaining a set rotation speed, and performing circular reciprocating polishing on the paint surface with the polishing point as the center, and the polishing lasting for a second set duration.

[0018] Furthermore, the second set duration is 7 to 9 seconds.

[0019] Furthermore, after performing ring-shaped uniform polishing on the paint surface using the eccentric polishing machine, the process also includes a full-area re-inspection of the paint surface by immersion in alcohol. The step of performing a full-area re-inspection of the paint surface by immersion in alcohol includes: cleaning the paint surface, and then wiping and immersing the polished area and the surrounding paint surface with anhydrous alcohol; observing the condition of the paint surface under natural light to check whether the paint surface has scratches and haze marks.

[0020] Furthermore, the lighting environment for observing the paint surface is configured with a CIE-D65 standard artificial daylight source to simulate diffused natural light; when inspecting the paint surface, the distance between the operator's eyes and the paint surface is no more than 50cm.

[0021] Furthermore, if the paint surface still has defects after inspection, the paint surface is repeatedly subjected to fixed-point rough polishing and circular fine polishing.

[0022] By employing the above technical solution, this invention enables standardized, segmented polishing of paint defects using an eccentric polishing machine. A single complete polishing operation is divided into two fixed processes, with the total operation time strictly locked at 12-15 seconds. The entire process, including actions, duration, and speed, is standardized. Through this quantified process of fixed speed, duration, and actions, reliance on manual experience is completely eliminated, allowing new employees to quickly master the standard operation and completely eliminating paint quality fluctuations caused by differences in personnel skills. The subsequent anhydrous alcohol wiping and re-inspection process alters the optical properties of the clear coat surface through alcohol immersion, simulating actual outdoor lighting conditions for vehicles. This makes subtle polishing marks and hidden haze, previously concealed under natural light, clearly visible, preventing defective products from flowing into the next process and forming a closed-loop quality control system from processing to inspection. Attached Figure Description

[0023] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0024] Figure 1 This is a schematic flowchart of a polishing method for eliminating polishing marks on vehicle paint surfaces, as described in an embodiment of this application.

[0025] Figure 2 This is a flowchart illustrating step 100 of the polishing method for eliminating polishing marks on vehicle paint surfaces in an embodiment of this application.

[0026] Figure 3 This is a schematic diagram showing the movement trajectories of the polishing cotton in the eccentric polishing machine and the polishing cotton in the concentric polishing machine in the embodiments of this application;

[0027] Figure 4 This is a bar chart comparing the paint surface working temperature of the polishing method in this application embodiment with that of the concentric polishing machine;

[0028] Figure 5This is a flowchart illustrating step 200 of the polishing method for eliminating polishing marks on vehicle paint surfaces in an embodiment of this application.

[0029] Figure 6 This is a schematic diagram illustrating the effects of point-to-point coarse polishing and circular fine polishing in the polishing method for eliminating polishing marks on vehicle paint surfaces, as described in the embodiments of this application.

[0030] Figure 7 This is a flowchart illustrating step 400 of the polishing method for eliminating polishing marks on vehicle paint in an embodiment of this application.

[0031] Figure 8 These are actual photos comparing paint surface defects detected by wiping with alcohol in the embodiments of this application.

[0032] Figure 9 Pareto chart showing the distribution of paint polishing defects on car bodies during production. Detailed Implementation

[0033] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0034] First, it should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "vertical," "horizontal," "longitudinal," "inner," and "outer," which indicate directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] like Figure 1 As shown in the figure, this application provides a polishing method for eliminating polishing marks on vehicle paint surfaces. The polishing method includes the following steps:

[0037] Step S100: Pre-treat the paint surface of the vehicle.

[0038] Before pre-treating the vehicle's paint surface, it is usually cleaned to remove adhering dust, fine particles, mold release residue, fly ash, and other impurities. After cleaning, the paint surface is dried, and then defects on the vehicle's paint surface are inspected. In the embodiments of this application, the paint surface defects inspected before pre-treatment are mainly raised defects, such as residual particle protrusions after the topcoat has cured, and minor runs.

[0039] like Figure 2 As shown, step 100 further includes the following steps:

[0040] Step 110: Fit the fine wet sandpaper onto the sanding end of the sander;

[0041] Step 120: Wet sanding is used to smooth out any raised defects on the painted surface, and the surface is sanded evenly.

[0042] Light wet sanding with 2000-grit sandpaper can be used to smooth the surface, sanding it at a uniform speed. This is specifically designed for pre-smoothing defects on the paint surface, such as paint spray particles and minor runs, providing a smooth base for subsequent standardized polishing processes. At the same time, by controlling the sanding force and stroke, over-sanding can be avoided to prevent the creation of new deep grooves and scratches on the paint surface.

[0043] Step S200: Use an eccentric polisher to perform spot rough polishing on the paint surface.

[0044] The eccentric polishing machine for point rough polishing is equipped with an eccentric shaft with a 12mm eccentricity, offset from the center of the polishing disc. The output end of the eccentric shaft is fitted with a non-perforated hard polishing disc, on which polishing cotton with distributed ventilation micropores is attached. During polishing, the eccentric polishing machine must ensure a rotational speed of 5000 RPM to guarantee polishing quality.

[0045] like Figure 3 As shown, the eccentric structure relies on a 12mm eccentric composite motion to disperse frictional heat, and combined with porous polishing cotton to achieve heat dissipation, thus solving the defect of high-temperature haze on the paint surface. In the figure, the concentric polishing machine on the left has a single concentric circle trajectory, with concentrated friction points, which is prone to producing local high-temperature scratches; the eccentric polishing machine on the right forms an interlaced cycloidal motion trajectory, with friction points evenly distributed, which can simultaneously polish and eliminate sandpaper residue and sanding marks.

[0046] Furthermore, such as Figure 4 As shown, under the same rotation speed and working time, the local peak temperature of concentric polishing is significantly higher; while the eccentric polishing fixture in this embodiment disperses heat, resulting in a lower paint surface temperature and avoiding high-temperature heat damage that could cause fogging.

[0047] like Figure 5As shown, step 200 further includes the following steps:

[0048] Step 210: Start the eccentric polishing machine and make sure the polishing cotton is in close vertical contact with all the polishing points on the paint surface.

[0049] Furthermore, the set speed is 5000 RPM.

[0050] Step 220: Position the eccentric polisher at the set speed and perform spot polishing on the paint surface for the first set time.

[0051] Furthermore, the initial setting time for the fixed-point rough polishing of the paint surface is 5 to 6 seconds.

[0052] Start the eccentric polishing equipment and make the polishing cotton vertically and tightly adhere to the polishing point (a certain defect) on the paint surface. Keep the speed of the eccentric polishing machine stable at 5000 RPM and maintain a fixed point of uniform cutting operation on the polishing point for 5-6 seconds. Quickly and thoroughly smooth out the deep grooves and obvious scratches on the paint surface produced by the water polishing process, and complete the basic repair of defects.

[0053] Step S300: Use an eccentric polisher to perform circular fine polishing on the painted surface.

[0054] Step S300 includes: the eccentric polishing machine maintains a set speed and performs circular reciprocating polishing on the paint surface with the polishing point as the center, and the polishing continues for a second set time.

[0055] Furthermore, the second set time for the circular polishing of the paint surface is 7 to 9 seconds.

[0056] like Figure 6 As shown, during the circular fine polishing of the paint surface, the eccentric polishing machine maintains the same rotation speed as the fixed-point rough polishing. A specific defect on the paint surface is selected as the polishing point, and the polishing is performed in a uniform circular motion for 7-9 seconds, centered on this point. During this process, the microporous heat dissipation structure of the polishing cotton evenly dissipates residual heat, eliminating polishing stress marks and surface haze. The total time for both the fixed-point rough polishing and the circular fine polishing processes is strictly controlled within 12-15 seconds to ensure the consistency of polishing quality for every defect on the paint surface.

[0057] Step 400: After performing a circular polishing of the paint surface using an eccentric polishing machine, the paint surface is then subjected to a full-area re-inspection by immersing it in alcohol.

[0058] like Figure 7 As shown, step 400 further includes the following steps:

[0059] Step 410: Clean the paint surface, and then use anhydrous alcohol to wipe and moisten the polished area and the surrounding paint surface.

[0060] Step 420: Observe the paint surface under natural light to check for scratches and haze.

[0061] Furthermore, the lighting environment for observing the paint surface is equipped with a CIE-D65 standard artificial daylight source to simulate diffused natural light. This allows for the simulation of natural lighting on the production line to inspect the polishing effect of the paint surface and accurately identify hidden haze marks and fine polishing scratches that are not visible to the naked eye. When inspecting the paint surface, the operator's eyes must be no more than 50cm away from the paint surface.

[0062] like Figure 8 As shown, the left side is under normal natural light for routine visual inspection (without using anhydrous alcohol). The subtle polishing marks and shallow haze hidden inside the paint surface have no obvious color difference and cannot be identified by the naked eye, which can easily lead to missed defects. The right side is under the condition of re-inspection after using anhydrous alcohol. After the alcohol changes the optical refraction effect of the paint surface, all hidden defects are clearly revealed, which can intercept defective products in advance and prevent rework problems after delivery.

[0063] Furthermore, after the paint surface inspection is passed, the vehicle can be transferred to the next painting process. If the vehicle still has defects after the paint surface inspection, the unqualified areas of the paint surface are repeatedly rough polished and fine polished in a circular pattern.

[0064] The polishing method for eliminating polishing marks on vehicle paint disclosed in this application employs a pneumatic eccentric polishing machine with a working speed of up to 5000 RPM. It features a polishing disc with an eccentricity of 12 mm and porous polishing cotton on the disc for heat dissipation. The eccentrically positioned polishing disc enables a large eccentric oscillating composite motion trajectory, expanding the polishing coverage area. High-speed cutting quickly smooths paint grooves while dispersing single-point frictional heat. The polishing cotton, with its distributed ventilation micropores, allows airflow to continuously exchange heat through the pores during operation, preventing localized high-temperature accumulation on the paint surface and avoiding heat burns and haze formation in the clear coat. The polishing disc has a solid, one-piece structure, ensuring polishing support rigidity and operational stability, and lacks heat dissipation holes. This approach simultaneously suppresses two core defects—grinding scratches and high-temperature haze—from both hardware and consumable perspectives, balancing polishing efficiency and paint protection.

[0065] Furthermore, this polishing method abandons the traditional, irregular, and uncontrolled manual polishing mode. A single complete polishing operation is broken down into two fixed processes—fixed-point rough polishing and circular fine polishing—with the total operation time strictly locked at 12-15 seconds. The entire process, including actions, duration, and speed, is standardized, completely eliminating reliance on human experience. The initial fixed-point rough polishing (5-6 seconds) focuses on cutting deep grooves left by sandpaper grinding, quickly filling scratches; the subsequent circular reciprocating polishing (7-9 seconds) uses low-speed circular polishing to continuously dissipate heat and eliminate polishing haze. Mass production verification has shown that this two-stage standardized process can reduce the overall vehicle polishing defect rate from 14.3% to below 0.5%, resulting in a significant quality improvement.

[0066] In actual production, Pareto chart data on polishing defects in mass production can be used to accurately identify high-risk areas for polishing large flat surfaces such as the hood and tailgate. During operations, a standardized two-stage polishing process is prioritized for areas with high defect rates, specifically addressing the problem of concentrated localized polishing defects. This achieves precise control over mass production defects and reduces the overall defect rate of the vehicle. Figure 9 As shown, Pareto statistics were used to analyze the polishing defects in high-frequency defect areas such as the hood and tailgate of the vehicle. Polishing marks accounted for 59% of all paint defects. Among them, sanding scratches accounted for 91.4% of polishing defects and polishing haze accounted for 8.6%. This data supports the core pain point that this invention needs to address.

[0067] Moreover, this polishing method innovatively adds a post-polishing anhydrous alcohol full-area wiping and re-inspection process. By immersing the product in alcohol, the optical properties of the clear coat surface are changed, simulating the actual outdoor lighting conditions of the vehicle. This makes the subtle polishing marks and hidden haze that are hidden under natural light clearly visible, thus preventing defective products from flowing into the next process in advance and forming a closed-loop quality control system of "processing-inspection".

[0068] The polishing method for eliminating polishing marks on vehicle paint surfaces disclosed in the embodiments of this application is used on the vehicle production line:

[0069] 1. Significantly improves mass production yield and boasts extremely high quality stability: Verified in mass production of complete vehicles, this invention reduces the paint polishing defect rate from 14.3% to below 0.5%, eradicating high-frequency defects such as polishing scratches and haze, and significantly improving the first-pass yield of the entire vehicle's paint surface. Simple to implement; only the polishing equipment needs to be replaced, requiring no modification to existing workstation tooling, and easy for employees to learn.

[0070] 2. High production line adaptability and extremely low modification cost: The entire set of polishing tools and standardized processes are fully compatible with existing coating and sanding production lines. No modifications to the workshop assembly line layout or additional specialized equipment are required. It can be quickly implemented and promoted across all personnel and production lines without significant modification costs. This reduces sanding and touch-up repairs, saving labor and polishing consumables.

[0071] 3. Standardized operations reduce the skill threshold for manual workers: Through a quantitative process with fixed rotation speed, fixed duration, and fixed actions, the reliance on the experience of senior technicians is completely eliminated. New employees can quickly get started and meet the standards, completely eliminating the fluctuations in paint quality caused by differences in personnel skills.

[0072] 4. Reduce costs and increase efficiency, and reduce resource consumption: Effectively reduce the frequency of paint surface rework and sanding, reduce the repeated consumption of auxiliary materials such as polishing cotton, sandpaper, and alcohol, and at the same time reduce the man-hours of rework stations, continuously optimizing workshop manufacturing costs and production rhythm.

[0073] 5. Closed-loop management throughout the entire process to eliminate after-sales risks: Through a triple management model of "pre-process precision polishing in zones + multi-hole heat dissipation and temperature control + final alcohol immersion re-inspection", polishing defects are intercepted throughout the entire process from production and processing to quality inspection, completely avoiding the risk of rework of paint defects and customer complaints after vehicle delivery.

[0074] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A polishing method for eliminating polishing marks on a vehicle finish, characterized in that, Includes the following steps: Pre-treatment of the vehicle's paint surface; The paint surface was rough polished at specific points using an eccentric polishing machine; The painted surface is subjected to ring-shaped fine polishing using the eccentric polishing machine.

2. The polishing method according to claim 1, wherein The pretreatment steps for the paint surface include: Fit fine wet sandpaper onto the sanding end of the sander; The raised defects on the paint surface are smoothed by wet sanding and polished evenly.

3. The polishing method according to claim 2, characterized in that, The eccentric polishing machine is equipped with an eccentric rotating shaft with an eccentric distance of 12mm; The output end of the eccentric shaft is provided with a non-porous hard polishing disc. Polishing cotton with distributed ventilation micropores is attached and installed on the non-porous hard polishing disc.

4. The polishing method according to claim 3, characterized in that, The step of performing targeted rough polishing on the paint surface includes: Start the eccentric polishing machine and make the polishing cotton fit vertically and tightly against the polishing points of the paint surface; The eccentric polishing machine is maintained at a set speed, and the paint surface is polished at specific points for a first set time.

5. The polishing method according to claim 4, characterized in that, The first set duration is 5-6 seconds; The set speed is 5000 RPM.

6. The polishing method according to claim 5, characterized in that, The step of performing circular fine polishing on the paint surface using the eccentric polishing machine includes: The eccentric polishing machine maintains a set rotation speed and performs circular reciprocating polishing on the paint surface with the polishing point as the center, and the polishing continues for a second set time.

7. The polishing method according to claim 6, characterized in that, The second set duration is 7 to 9 seconds.

8. The polishing method according to claim 7, characterized in that, After performing ring-shaped uniform polishing on the paint surface using the eccentric polishing machine, the process also includes a full-area re-inspection of the paint surface by immersion in alcohol. The steps for performing a full-area re-inspection of the painted surface by immersion in alcohol include: Clean the paint surface, and then use anhydrous alcohol to wipe and moisten the entire paint surface of the polished area and its surroundings. Observe the paint surface under natural light to check for scratches and haze.

9. The polishing method according to claim 8, characterized in that, The lighting environment of the painted surface was observed using a CIE-D65 standard artificial daylight source to simulate diffused natural light; When inspecting the paint surface, the distance between the operator's eyes and the paint surface should not exceed 50cm.

10. The polishing method according to claim 9, characterized in that, If the paint surface still has defects after inspection, the paint surface is repeatedly subjected to fixed-point rough polishing and circular fine polishing.

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