A pre-oiling auxiliary device for placing thin spring clips

Abstract

This invention relates to a pre-oiling auxiliary device for placing thin, lightweight spring pieces, belonging to the field of precision assembly technology. It includes a robotic arm, an oiling mechanism, a vision system, and a reflective analysis module. The oiling mechanism and vision system are mounted on the robotic arm, which is used to pick up and place the spring pieces. The oiling mechanism performs an oiling action before placing the spring pieces onto the workpiece. The vision system includes an industrial camera, a ring-shaped coaxial light source, and a polarizer. The industrial camera is mounted on the robotic arm, and the ring-shaped coaxial light source and the industrial camera are coaxially nested. The polarizer is attached to the output surface of the light source. The industrial camera is connected to the reflective analysis module, which uploads the captured oiling image of the workpiece to the reflective analysis module. The reflective analysis module determines the effectiveness of the oiling by identifying the brightness enhancement characteristics of the oiled area relative to the unoiled area. The adhesive force generated by the pre-oiling solves the problem of thin, lightweight spring pieces being easily affected by airflow and static electricity, causing them to fall or be misaligned, fundamentally improving the physical stability of placement.

Description

Technical Field

[0001] This invention belongs to the field of precision assembly technology, specifically relating to a pre-oiling auxiliary device for placing thin and light spring pieces. Background Technology

[0002] In the assembly processes of precision electronics, microelectromechanical systems (MEMS), and micro connectors, it is often necessary to handle tiny, thin metal springs. These springs typically serve as electrical contacts, mechanical sensing elements, or elastic support structures, and the accuracy and reliability of their mounting position directly determine the performance and yield of the final product. However, the automated handling of these thin springs faces significant challenges, including static electricity issues and high airflow sensitivity.

[0003] The contact spring is prone to triboelectric charging. Its extremely small mass and ultra-thin thickness result in a very high surface area to volume ratio, making it easy for static charge to accumulate and difficult to dissipate. During the pickup process, static electricity can cause the contact spring to abnormally adhere to the tray or carrier belt, making pickup difficult. During the placement process, the static force will resist the release action, causing the contact spring to fail to detach smoothly from the nozzle, or after detachment, it may deviate from the preset position due to the electrostatic adsorption effect, resulting in missed placement or positional deviation.

[0004] Currently, mainstream automation solutions such as four-axis robotic arms typically use end-effector negative pressure suction nozzles for suction. However, for smooth, ultra-thin spring sheets, the effective contact area between the nozzle end face and the spring sheet is small, resulting in weak and potentially uneven suction force. This makes the spring sheets prone to displacement or detachment during equipment acceleration / deceleration or vibration. Solutions primarily rely on closing the negative pressure and / or applying brief positive pressure. Closing the negative pressure cannot effectively overcome electrostatic adhesion; applying air introduces a strong, uncontrollable airflow, which can easily blow away or deviate the thin spring sheets, especially when there is ambient airflow interference, making success rates difficult to guarantee.

[0005] Therefore, a pre-oiling auxiliary device is needed to stably and accurately complete the picking and placing of shrapnel. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a pre-oiling auxiliary device for placing thin and light spring sheets. This solves the problem that existing ultra-thin spring sheets are easily affected by airflow and static electricity during the picking and placing process, leading to inaccurate picking and placing positions, and the easy occurrence of missing or misaligned placement.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A pre-oiling auxiliary device for placing thin spring pieces includes a robotic arm, an oiling mechanism, a vision system, and a reflectivity analysis module; the oiling mechanism and the vision system are mounted on the robotic arm, which is used to pick up and place the spring pieces, and the oiling mechanism is used to perform an oiling action before placing the spring pieces onto the workpiece;

[0009] The vision system includes an industrial camera, a ring-shaped coaxial light source, and a polarizer. The industrial camera is mounted on the robotic arm, and the ring-shaped coaxial light source and the industrial camera are coaxially nested. The polarizer is attached to the output surface of the light source. The industrial camera is connected to the reflection analysis module, which uploads the captured oil-spraying image of the workpiece to the reflection analysis module. The reflection analysis module determines the effectiveness of oil spraying by identifying the brightness enhancement feature of the oil-sprayed area relative to the unsprayed area.

[0010] Preferably, the oiling mechanism includes an oil tank, an oil pump, a nozzle, and a control valve. The oil pump delivers viscous oil from the oil tank to the nozzle, the nozzle applies oil to the workpiece surface, and the control valve controls the opening and closing of the nozzle.

[0011] Preferably, the viscous oil is a silicone-based viscous oil with added titanium dioxide reflective particles.

[0012] Preferably, the nozzle has a conical diffusion cavity at its outlet end, which makes the sprayed oil droplets form an annular protrusion structure that is thin in the center and thick at the edges. The inclination angle of the conical diffusion cavity is 45°±5.

[0013] Preferably, the reflectivity analysis module performs the following operations:

[0014] Polarization difference processing: Acquire reference images with the light source on and without polarization, feature images under orthogonal polarization, and generate difference images;

[0015] Feature region extraction: Select the target point oil region and adjacent oil-free regions in the difference image;

[0016] Brightness enhancement verification: If the average gray value of the oil-sprayed area is greater than the average gray value of the adjacent unsprayed area, it is determined that there is brightness enhancement.

[0017] Preferably, it also includes an intelligent fuel quantity mapping controller, which has a pre-stored three-dimensional mapping table of fuel film area-injection quantity-adhesion force, and executes:

[0018] a) Based on the oil film area measured by the oil film reflection analysis module, the target fuel injection quantity level is determined by consulting the mapping table: small area → low fuel injection quantity; medium area → medium fuel injection quantity; large area → high fuel injection quantity.

[0019] b) Convert the injection quantity level to the control valve pulse width: low injection quantity → short pulse; medium injection quantity → medium pulse; high injection quantity → long pulse.

[0020] Preferably, the annular coaxial light source is a multispectral tunable light source, including blue and red light bands, and the contrast between the oil film and the background is optimized by switching the light source bands.

[0021] Preferably, it also includes a pressure sensor and a status analysis unit disposed on the robotic arm;

[0022] The pressure sensor is used to monitor the pressing force applied to the spring in real time when the spring is placed;

[0023] The status analysis unit is connected to the industrial camera and the pressure sensor, and performs the following operations:

[0024] a) When the pressing force reaches a preset pressure threshold, the industrial camera is triggered to take a picture of the workpiece after the spring is placed, and to obtain an image of the spring status.

[0025] b) Analyze the state image of the spring piece, identify the edge features of the spring piece and compare them with the preset placement position to determine whether the spring piece has a positional offset or warping;

[0026] c) If a positional offset or warping exceeding the threshold is detected, the current workpiece is marked as defective.

[0027] Preferably, the vision system further includes a liquid lens module disposed in the optical path of an industrial camera, and the liquid lens module is controlled by voltage.

[0028] The beneficial effects of this invention are as follows:

[0029] The adhesive force generated by the pre-oiling in this application solves the problem of thin and light springs being easily affected by airflow and static electricity, leading to displacement, drifting, and misalignment. It fundamentally improves the physical stability of placement. The optical analysis module detects the effectiveness of oiling in real time, ensuring that the adhesive force is reliably present before each placement, avoiding placement problems caused by oiling failure, greatly reducing the risk of missed placement or misalignment, effectively solving the core interference factors in the picking and placing process and ensuring oiling quality. It greatly reduces product defects or subsequent assembly failures caused by inaccurate spring position, missed placement, or misalignment, directly improving product yield and the overall reliability of the production line. Attached Figure Description

[0030] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the pre-oiling auxiliary device control provided in one embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the pre-oiling auxiliary device provided in one embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the vision system structure provided in one embodiment of the present invention;

[0034] Legend: 1. Robotic arm; 21. Nozzle; 3. Vision system; 31. Industrial camera; 32. Ring coaxial light source; 33. Polarizer. Detailed Implementation

[0035] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0036] like Figures 1-3 As shown, a pre-oiling auxiliary device for placing thin spring clips includes a robotic arm 1, an oiling mechanism, a vision system 3, and a reflectivity analysis module. The oiling mechanism and vision system 3 are mounted on the robotic arm 1, which is used to pick up and place the spring clips. The oiling mechanism is used to perform an oiling action before placing the spring clips onto the workpiece. Utilizing the physical properties of oil, before the spring clips are placed at the target workpiece position, the oiling mechanism sprays a small amount of oil onto the corresponding position of the target workpiece. The oil film generates a slight adhesive force. When the robotic arm 1 places the spring clips at the target position, this adhesive oil film can effectively increase the adhesion between the spring clips and the workpiece surface, preventing slight airflow from blowing the spring clips out of place. At the same time, the oil film, as a physical contact layer, helps to release or neutralize static charge, reducing the problems of spring clips jumping up, shifting, or adhering to the nozzle due to electrostatic repulsion / attraction.

[0037] The vision system 3 includes an industrial camera 31, a ring-shaped coaxial light source 32, and a polarizer 33. The industrial camera 31 is mounted on the robot arm 1, and the ring-shaped coaxial light source 32 and the industrial camera 31 are coaxially nested. The polarizer 33 is attached to the output surface of the light source. The industrial camera 31 is connected to a reflection analysis module, which uploads the captured oil-spraying image of the workpiece to the reflection analysis module. The reflection analysis module determines the effectiveness of oil spraying by identifying the brightness enhancement characteristics of the oil-sprayed area relative to the unsprayed area. The reflection analysis module utilizes the phenomenon that the oil film changes the surface optical reflection characteristics. Under specific lighting conditions, the intensity and distribution of reflected light differ between the oil-sprayed area (with oil) and the unsprayed area (substrate). The oil film usually forms a smooth surface, producing more concentrated specular reflection, or changes the diffuse reflection characteristics, causing it to exhibit higher local brightness in the processed image than the surrounding unsprayed area. By determining whether the oil-sprayed area has the expected brightness enhancement pattern, the effectiveness of the oil spraying can be determined. If the oil spraying is ineffective, it is recorded as a defect rate, and the workpiece will not be assembled in subsequent assembly processes. This achieves the desired processing quality.

[0038] In summary, the adhesive force generated by pre-oiling solves the problem of thin springs being easily affected by airflow and static electricity, leading to displacement, drifting, and misalignment. This fundamentally improves the physical stability of placement. The optical analysis module detects the effectiveness of oiling in real time, ensuring that the adhesive force is reliably present before each placement. This avoids placement problems caused by oiling failure, greatly reduces the risk of missed placement or misalignment, effectively solves the core interference factors in the picking and placing process, and ensures the quality of oiling. It greatly reduces product defects or subsequent assembly failures caused by inaccurate spring positions, missed placements, or misalignment, directly improving product yield and the overall reliability of the production line.

[0039] In one embodiment, the oil dispensing mechanism includes an oil tank, an oil pump, a nozzle 21, and a control valve. The oil pump delivers viscous oil from the oil tank to the nozzle 21, which dispenses oil onto the workpiece surface. The control valve controls the opening and closing of the nozzle 21. The oil tank stores a sufficient amount of dedicated viscous oil, and the oil pump provides stable and adjustable pressure to extract the viscous oil from the oil tank and deliver it to the nozzle 21 pipeline. The nozzle 21 is the terminal component that performs the oil dispensing action. When the control valve is opened, high-pressure oil flows through the nozzle 21. When the oil flow is ejected at high speed from the tip of the nozzle 21, its kinetic energy overcomes the surface tension and viscosity of the oil itself, forming a tiny oil droplet. The control valve is installed between the oil pump and the nozzle 21. After receiving the oil dispensing command signal, the solenoid valve coil is instantly energized, and the valve core moves at high speed, opening the oil passage. High-pressure oil flows through the valve to the nozzle 21, and begins to spray oil droplets.

[0040] In one embodiment, the viscous oil is a silicone-based viscous oil with added titanium dioxide reflective microparticles. The oil film alters the light reflection characteristics of the workpiece. Compared to an oil-free, rough, or diffusely reflective surface, a smooth oil film produces stronger specular reflection. The sheet-like microparticles in the silicone oil tend to align parallel to the substrate surface of the workpiece, allowing the flat surfaces of the microparticles to act like countless tiny mirrors, directionally and efficiently reflecting incident light back towards the light source and camera. Compared to spherical particles, sheet-like particles have a lower specific surface area and a more regular reflective surface, reducing diffuse scattering of light and concentrating the reflected light.

[0041] In summary, by adding titanium dioxide reflective microparticles to silicone-based viscous oil, the oil dispensing effect detection principle of this pre-dispensing auxiliary device has been upgraded from relying on "brightness changes caused by the weak specular reflection of the oil film itself" to detecting "significantly bright marks formed by the directional arrangement of highly reflective microparticles." This design actively enhances the optical signal to be detected, resulting in a comprehensive improvement in detection reliability, accuracy, speed, and anti-interference capability. This makes the "reflective analysis module" more accurate in judging the effectiveness of oil dispensing, thereby further ensuring the accuracy of the placement of thin spring sheets and the yield of the entire production process.

[0042] In one embodiment, the nozzle 21 has a conical diffusion cavity at its outlet end, which causes the sprayed oil droplets to form an annular protrusion structure that is thin in the center and thick at the edges. The inclination angle of the conical diffusion cavity is 45°±5°. When the viscous oil flows at high speed through the end of the nozzle 21 under pressure, it suddenly encounters the conical diffusion cavity with an inclination angle of 45°. According to the principle of fluid dynamics, the conical cavity causes the oil flow to suddenly enter the open space from the narrow outlet, the flow velocity drops sharply, the pressure is released, and the oil diffuses radially along the inclination angle of the conical surface, forming a thin laminar flow that spreads outwards. The wetting effect between the viscous oil and the conical cavity wall generates adhesion, which further pushes the oil to move along the conical surface to the outer edge. The central part of the oil flow continues to move forward due to inertia, but lacks the support of the cavity wall. Under the action of gravity and surface tension, it quickly collapses and thins, forming a depression. When the oil reaches the edge of the conical cavity, it is constrained by the tension balance of the gas-liquid-solid three-phase interface, and the contact line is restricted to the edge corner. The subsequent oil is continuously transported, accumulating to form a thick annular protrusion.

[0043] Due to the large thickness of the oil film, the annular raised area forms a dense reflective layer at the edge, which appears as a bright white high-contrast ring under polarized light imaging. The thin oil area in the center reflects very little light, forming a clear dark center in the image. Together with the bright ring, it constitutes a "dual feature of light and dark", providing a precise target for vision system 3.

[0044] In one embodiment, the reflectivity analysis module performs the following operations:

[0045] Polarization difference processing: Acquire reference images with the light source on and without polarization, feature images under orthogonal polarization, and generate difference images;

[0046] Feature region extraction: Select the target point oil region and adjacent oil-free regions in the difference image;

[0047] Brightness enhancement verification: If the average gray value of the oil-sprayed area is greater than the average gray value of the adjacent unsprayed area, it is determined that there is brightness enhancement, and the effective oil-sprayed area contains... The microparticle oil film produces depolarized reflection, and its gray value in the differential image is significantly higher than that of the oil-free area, which deeply integrates optical physical properties with intelligent algorithms.

[0048] In one embodiment, it also includes an intelligent oil quantity mapping controller, which has a three-dimensional mapping table of oil film area-injection quantity-adhesion force stored in it, and executes the following: The mapping table is established through a large amount of experimental, simulation or empirical data, and records the optimal injection quantity required to achieve the best adhesion force effect under a specific oil film area, taking into account the influence of various factors such as the characteristics of lubricating oil, surface condition, temperature and other factors on adhesion force.

[0049] a) Based on the oil film area measured by the oil film reflection analysis module, the target oil injection quantity level is determined by querying the mapping table: small area → low oil injection quantity; medium area → medium oil injection quantity; large area → high oil injection quantity. The oil film reflection analysis module monitors the state of the lubricating surface in real time, especially measuring the area of ​​the currently formed lubricating oil film, and transmits these measurement results to the intelligent oil quantity mapping controller in real time.

[0050] b) Convert the fuel injection quantity level into the control valve pulse width. The opening and closing of the fuel injection valve is usually controlled by an electrical pulse signal. The pulse width directly determines the length of time the valve is open, which in turn determines the final amount of fuel injected: low fuel injection quantity → short pulse; medium fuel injection quantity → medium pulse; high fuel injection quantity → long pulse.

[0051] The intelligent oil volume mapping controller uses the oil film area measured by the reflection analysis module to query the optimal oil injection parameters through a three-dimensional mapping table of oil film area-injection quantity-adhesion force. For example, a low oil injection quantity is used for small oil film areas to avoid oil contamination, while a high oil injection quantity is used for large oil film areas to ensure coverage integrity. Instead of using a fixed oil injection quantity or simple open-loop control, it can dynamically adjust the oil injection quantity according to actual lubrication needs. While ensuring that key components are adequately lubricated, it reduces unnecessary lubricant consumption and potential pollution, which helps to improve the overall efficiency and operational reliability of the equipment.

[0052] In one embodiment, the annular coaxial light source 32 is a multispectral tunable light source, including blue and red light bands. By switching the light source bands, the contrast between the oil film and the background is optimized. The multispectral tunable light source achieves dynamic optimization of the contrast between the oil film and the background through the synergistic effect of blue and red light. The working principle is based on the difference in optical characteristics of the two bands, which respectively enhance the surface reflection of the oil film and the details of the workpiece, thereby improving the detection accuracy and equipment adaptability, and providing support for the high-precision placement of thin and light springs.

[0053] In one embodiment, it also includes a pressure sensor and a state analysis unit disposed on the robotic arm 1;

[0054] The pressure sensor is used to monitor the pressing force applied to the spring in real time when placing the spring, and to monitor the pressing force value at the end of the robot arm 1 in real time. It converts the physical assembly force into an electrical signal, provides a dynamic reference for triggering detection, and solves the problem of missed detection caused by traditional fixed-sequence photography. The state analysis unit serves as the core of data processing and establishes the linkage logic between the pressure signal and visual detection.

[0055] The status analysis unit connects to the industrial camera 31 and the pressure sensor, and performs the following operations:

[0056] a) When the pressing pressure reaches the preset pressure threshold, the industrial camera 31 is triggered to take a picture of the workpiece after the spring is placed, and the spring status image is obtained. When the pressure value is greater than the threshold, it indicates that the spring has stably contacted the workpiece surface. Taking pictures at this time can avoid image blurring caused by the vibration of the robotic arm and ensure the accuracy of the detection timing.

[0057] b) Analyze the image of the spring clip state, extract the coordinates of the corner points of the spring clip outline, calculate the Euclidean distance with the preset reference position, calculate the deformation through the warping angle, and transform subjective visual inspection into objective quantitative indicators;

[0058] c) If a positional offset or warping is detected to exceed the threshold, the workpiece is marked as a non-conforming item based on the offset / warping amount exceeding the tolerance, so that the current workpiece is not assembled in the next process assembly.

[0059] In one embodiment, the vision system 3 further includes a liquid lens module disposed in the optical path of the industrial camera 31. By voltage-controlled liquid lens module, the curvature of the liquid surface is adjusted by changing the voltage of the liquid lens electrode to achieve rapid zoom. During the placement of the spring, the lens first shoots the oil dot area in telephoto mode, and then switches to short-focus mode to detect the edge details of the spring. Dynamic focusing eliminates vibration interference caused by mechanical movement and improves image clarity.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A pre-oiling auxiliary device for placing thin spring clips, characterized in that, It includes a robotic arm, an oiling mechanism, a vision system, and a reflectivity analysis module; the oiling mechanism and the vision system are mounted on the robotic arm, which is used to pick up and place spring clips, and the oiling mechanism is used to perform an oiling action before placing the spring clips onto the workpiece; The vision system includes an industrial camera, a ring-shaped coaxial light source, and a polarizer. The industrial camera is mounted on the robotic arm, and the ring-shaped coaxial light source and the industrial camera are coaxially nested. The polarizer is attached to the output surface of the light source. The industrial camera is connected to the reflection analysis module, which uploads the captured oil-spraying image of the workpiece to the reflection analysis module. The reflection analysis module determines the effectiveness of oil spraying by identifying the brightness enhancement feature of the oil-sprayed area relative to the unsprayed area. The reflection analysis module performs the following operations: polarization difference processing: acquiring reference images with the light source on and without polarization, and feature images under orthogonal polarization, and generating a difference image; Feature region extraction: Select the target point oil region and adjacent oil-free regions in the difference image; Brightness enhancement verification: If the average gray value of the oil-sprayed area is greater than the average gray value of the adjacent unsprayed area, it is determined that there is brightness enhancement.

2. The pre-oiling auxiliary device for placing thin spring pieces according to claim 1, characterized in that, The oiling mechanism includes an oil tank, an oil pump, a nozzle, and a control valve. The oil pump delivers viscous oil from the oil tank to the nozzle, which then applies oil to the surface of the workpiece. The control valve controls the opening and closing of the nozzle.

3. The pre-oiling auxiliary device for placing thin spring pieces according to claim 2, characterized in that, The viscous oil is a silicone-based viscous oil with added titanium dioxide reflective particles.

4. The pre-oiling auxiliary device for placing thin spring pieces according to claim 2, characterized in that, The nozzle has a conical diffusion cavity at its outlet end, which makes the sprayed oil droplets form an annular protrusion structure that is thin in the center and thick at the edges. The inclination angle of the conical diffusion cavity is 45°±5.

5. The pre-oiling auxiliary device for placing thin spring pieces according to claim 1, characterized in that, It also includes an intelligent fuel quantity mapping controller, which has a pre-stored three-dimensional mapping table of fuel film area-injection quantity-adhesion force, and executes: a) Based on the oil film area measured by the oil film reflection analysis module, the target fuel injection quantity level is determined by consulting the mapping table: small area → low fuel injection quantity; medium area → medium fuel injection quantity; large area → high fuel injection quantity. b) Convert the injection quantity level to the control valve pulse width: low injection quantity → short pulse; medium injection quantity → medium pulse; high injection quantity → long pulse.

6. The pre-oiling auxiliary device for placing thin spring pieces according to claim 1, characterized in that, The annular coaxial light source is a multi-spectral adjustable light source, including blue and red light bands, and the contrast between the oil film and the background is optimized by switching the light source bands.

7. The pre-oiling auxiliary device for placing thin spring pieces according to claim 1, characterized in that, It also includes a pressure sensor and a status analysis unit installed on the robotic arm; The pressure sensor is used to monitor the pressing force applied to the spring in real time when the spring is placed; The status analysis unit is connected to the industrial camera and the pressure sensor, and performs the following operations: a) When the pressing force reaches a preset pressure threshold, the industrial camera is triggered to take a picture of the workpiece after the spring is placed, and to obtain an image of the spring status. b) Analyze the state image of the spring piece, identify the edge features of the spring piece and compare them with the preset placement position to determine whether the spring piece has a positional offset or warping; c) If a positional offset or warping is detected that exceeds the threshold, the current workpiece is marked as a defective product.

8. The pre-oiling auxiliary device for placing thin spring pieces according to claim 1, characterized in that, The vision system also includes a liquid lens module disposed in the optical path of an industrial camera, and the liquid lens module is regulated by voltage.

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