4. DESCRIPTION

Technical Field of the Invention

The invention relates to the painting technology in automotive industry. More specifically, it relates to the inkjet supply system of paint up to print head mounted on a robotic system.

Background of the Invention

In various painting processes, such as automotive painting, achieving high-quality results can be a time-consuming and challenging task. Conventional methods often involve using air-pressured spray guns that emit a conical spray pattern. However, these methods have limitations when it comes to efficiency and precision.

When using spray guns positioned at a distance from the target surface, the spray coverage becomes wider but slower. As a result, the paint may not effectively reach the surface, leading to inconsistencies and reduced uniformity in the paint coating. Additionally, the limited distance range for optimal spraying further compromises efficiency and prolongs the overall painting process.

To overcome these limitations and improve painting efficiency, there is a need for a paint supply system that can deliver paint directly to a print head mounted on a robotic system. Such a system offers several advantages, including zero material wastage, cost-effectiveness, time-saving, and the elimination of masking requirements. Additionally, this system enables extremely fast painting speeds of up to 2 meter per second, resulting in enhanced productivity and reduced painting time. By utilizing a robotic system-mounted drop on demand print head and an accessory efficient paint supply system, the invention addresses these challenges and aims to revolutionize the painting industry. The system enables precise control and direct application of paint, eliminating the need for additional masking and ensuring consistent and high-quality paint coatings. It also significantly reduces material wastage, lowers painting costs, and minimizes environmental pollution associated with traditional painting methods.

Overall, the invention aims to enhance painting processes, improve efficiency, and deliver superior paint results in various applications, including automotive painting and other commercial and domestic settings.

Brief Summary of the Invention

The following presents a simplified summary of the disclosure in order to provide a basic understanding to the reader. This summary is not an extensive overview of the disclosure, and it does not identify key/critical elements of the invention or delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to the more detailed description that is presented later.

Objects of the Invention:

Efficiency: The primary object of the invention is to provide a high transfer efficient painting system that reduces manual labor and improves productivity. By automating the paint application process, the system eliminates the need for manual painting, resulting in time and cost savings. Precision: Another object of the invention is to achieve precise and consistent paint application. Ensuring a uniform and accurate distribution of paint onto the desired surface.

Waste Reduction: The invention aims to minimize paint wastage and spillage. By accurately controlling the amount of paint supplied and removing excess paint from the print head, the system significantly reduces waste, leading to cost savings and environmental benefits.

Applications of the Invention:

Industrial Painting: The robotic painting system finds extensive application in industrial settings, such as automotive manufacturing, aerospace, and furniture production. It streamlines the painting process, enhances efficiency, and improves the overall quality of painted products.

Construction and Infrastructure: The system can be used in construction and infrastructure projects for painting large surfaces like walls, ceilings, and facades. It ensures uniform and precise paint application, reducing the need for manual labor and ensuring a professional finish.

Art and Design: The robotic painting system also has applications in the field of art and design. Artists and designers can utilize the system to automate repetitive painting tasks or create intricate and precise patterns with ease.

According to an aspect of the present invention, a robotic painting system is disclosed. The system comprises a control unit, a bulk reservoir, an inlet tank, feed pumps (1&2), a suction pump, an inlet pressure transmitter, a suction pressure transmitter, and a print head. In operation, the bulk reservoir tank is filled with paint to be supplied to the print head. The paint is transferred from the bulk reservoir to the inlet tank through feed pump 1 with a controlled flow rate of 100+/- 10 ml/min and a pressure head of 1 bar. This controlled transfer ensures a consistent and regulated supply of paint to the drop on demand print head.

To maintain a differential pressure between the inlet and outlet of the print head, the control unit receives pressure data from the inlet pressure transmitter and the suction pressure transmitter. Based on the received data, the control unit operates the feed pumps (1&2) accordingly. The inlet pressure transmitter ranges from 0 to 1 bar with an output range of 0 to 5VDC, while the suction pressure transmitter ranges from -1 to 1 bar with an output range of 0 to 5VDC.

The feed pump 2 of the system supplies paint to the print head through the inlet pressure transmitter with a specified flow rate and a pressure. This controlled supply ensures accurate and precise paint application by the print head onto the desired surface.

The print head plays a crucial role in the system by applying the paint to the required surface in a controlled and even manner. As the painting process concludes, the suction pump with a specified flow rate and a suction pressure is employed to remove excess paint from the print head through the outlet pressure transmitter. This prevents dripping or over-application of paint and ensures a clean and well-defined painting outcome. The excess paint recovered from the print head is then efficiently returned to the bulk reservoir for future use or recycling, reducing wastage and spillage compared to existing processes.

The robotic painting system of the present invention offers several advantages over conventional painting techniques. By positioning the system components away from the robotic system, except for the print head which is mounted on the system, the system provides flexibility and ease of operation. Moreover, the system eliminates the need for masking as it ensures controlled and even painting, resulting in enhanced productivity and efficiency. Additionally, the system reduces paint wastage and spillage, contributing to cost savings and environmental sustainability.

In summary, the present invention discloses a robotic painting system and method that enable efficient and controlled paint application in the automotive industries. By utilizing a control unit, pressure transmitters, and strategically positioned feed pumps and suction pump, the system ensures regulated paint supply, accurate differential pressure control, and effective removal of excess paint. The print head, mounted on the robotic system, applies the paint to the desired surface, eliminating the need for masking. The system's features result in enhanced productivity, reduced paint wastage, and improved environmental sustainability compared to existing processes.

Advantages of the Invention:

Enhanced Efficiency: By automating the painting process, the robotic system reduces the time and effort required for painting tasks. This results in increased productivity, allowing businesses to complete projects more quickly and efficiently.

Improved Quality: The precise control and uniform paint distribution provided by the system lead to improved quality and aesthetics of the painted surfaces. It eliminates inconsistencies and imperfections that may arise from manual painting, ensuring a high-quality finish.

Cost Savings: The system helps reduce material wastage and spillage, resulting in cost savings for paint supplies. Additionally, the automation of painting tasks reduces the need for manual labor, minimizing labor costs and improving overall operational efficiency.

Safety and Ergonomics: By automating the painting process, the robotic system reduces the exposure of workers to potentially hazardous paint fumes and repetitive motion injuries associated with manual painting. It creates a safer and more ergonomic working environment.

Overall, the robotic painting system offers numerous benefits, including increased efficiency, improved quality, cost savings, and enhanced worker safety. Its applications span various industries and can revolutionize the way paint is applied to surfaces, making it a valuable invention in the field of automated painting technology.

Brief Description of the Drawings

The invention will be further understood from the following detailed description of a preferred embodiment taken in conjunction with an appended drawing, in which:

Fig. 1 illustrates the block diagram of a robotic supply system, according to the exemplary embodiment of the present invention;

Fig. 2 illustrates the print head pressure regulation of desired range for optimal performance between -10 to lOkPa according to the exemplary embodiment of the present invention.

Detailed Description of the Invention It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

The use of “including”, “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. Further, the use of terms “first”, “second”, and “third”, and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

This detailed description of the invention highlights the key components, their functionalities, the method of operation, and the advantages offered by the robotic painting system and method according to the present invention.

According to an exemplary embodiment of the present invention, a control system for robotic painting is disclosed. In accordance with the aspect of the present invention, wherein the system comprises a control unit, a bulk reservoir, an inlet tank, feed pumps (1&2), a suction pump, a set of two dampers, an inlet pressure transmitter, a suction pressure transmitter, a print head, plurality of pressure sensors configured to regulate pressures at the print head based on the changes in the vertical height from the print head center.

In accordance with the exemplary embodiment of the present invention, the said pressure sensors are provided at inlet and outlet of the print head to monitor and regulate pressures. In accordance with the exemplary embodiment of the present invention, the said bulk reservoir tank stores paint to be supplied to the print head, and the paint is transferred from the bulk reservoir to the inlet tank through feed pump 1.

In accordance with the exemplary embodiment of the present invention, the said control unit receives pressure data from the pressure transmitters and operates the pumps to maintain a differential pressure between the inlet and outlet of the print head.

In accordance with the exemplary embodiment of the present invention, the feed pump 2 supplies paint to the print head through the inlet pressure transmitter. A set of dampers are connected between feed pump 2 and input pressure transmitter as well as between suction pump and outlet pressure transmitter to reduce pulsation and promote stable jetting behavior and the control signals of the feed pumps are varied based on the feedback from control unit.

In accordance with the exemplary embodiment of the present invention, the print head is responsible for applying paint to the desired surface. The said print head operates in X, Y and Z directions regulating the flow rate of the paint supply based on the feedback of sensors. The control unit regulates the pressure with respect to height to maintain pressure consistency. The suction pump removes excess paint from the print head through the outlet pressure transmitter after the painting process, and the excess paint is returned to the bulk reservoir through a damper.

In accordance with the exemplary embodiment of the present invention, wherein the components of the system are positioned away from the robotic system, except for the print head and the pressure transmitter which is mounted on the robotic system. In accordance with the exemplary embodiment of the present invention, wherein the system reduces wastage and spillage of paint compared to existing processes and eliminates the need for masking as it ensures controlled and even painting.

In accordance with the exemplary embodiment of the present invention, wherein the system comprising a controller that adjusts the flow rate of paint supplied.

In accordance with the exemplary embodiment of the present invention, wherein the control unit of the system adjusts the operation of the feed pumps to compensate for variations in paint viscosity, ensuring a consistent and controlled paint flow.

In accordance with the exemplary embodiment of the present invention, wherein the pressure sensors of the system at the inlet and outlet of the print head provide realtime feedback to the control unit, allowing for precise regulation of the paint pressure and preventing issues such as paint splattering, drooling, bubbles or inadequate coverage.

In accordance with the exemplary embodiment of the present invention, wherein the suction pump of the system operates at variable speeds based on the feedback from the outlet pressure transmitter, effectively removing excess paint while minimizing paint loss and waste.

In accordance with the exemplary embodiment of the present invention, the control unit of the system monitors and adjusts the paint flow and pressure in real-time, compensating for changes in the surface geometry or contours being painted to ensure uniform paint application.

In accordance with the exemplary embodiment of the present invention, a user interface that allows operators to input painting parameters, select paint colors, adjust paint thickness, designs and monitor the painting process, with the control unit executing the desired settings.

In accordance with the exemplary embodiment of the present invention, the system is configured to operate in conjunction with an automated surface scanning system that captures surface data, enabling the control unit to dynamically adapt the painting process to irregular or complex surfaces.

In accordance with the exemplary embodiment of the present invention, the inlet tank of the system is equipped with a level sensor that provides feedback to the control unit, ensuring a continuous paint supply by activating the feed pumps when the paint level is low.

In accordance with the exemplary embodiment of the present invention, the system comprises a paint filtration mechanism positioned between the bulk reservoir and the inlet tank, ensuring that the paint supplied to the print head is free from contaminants or impurities.

In accordance with the exemplary embodiment of the present invention, the control unit of the system utilizes machine learning algorithms to analyze real-time feedback from the pressure sensors and optimize the paint flow and pressure settings for improved painting efficiency and quality.

In accordance with the exemplary embodiment of the present invention, the control unit of the system is configured to monitor the paint consumption and provide alerts or notifications when the paint level in the bulk reservoir or inlet tank is low, enabling timely refill and uninterrupted painting operation. In accordance with the exemplary embodiment of the present invention, the system comprises an automated cleaning mechanism/purging for the print head, ensuring efficient paint color changeovers and minimizing color contamination during the painting process.

In accordance with the exemplary embodiment of the present invention, the control unit of the system integrates with a remote monitoring and control system, enabling remote access, monitoring, and control of the robotic painting system from a central location or through a connected device.

In accordance with the exemplary embodiment of the present invention, the robotic system carrying the print head is equipped with additional sensors or cameras to provide real-time feedback on the position, orientation, or distance between the print head and the target surface, enhancing the precision and accuracy of the painting process.

In accordance with the exemplary embodiment of the present invention, the control unit of the system employs predictive maintenance algorithms to monitor the health and performance of the pumps, pressure sensors, and other components, facilitating proactive maintenance and reducing downtime.

Now referring to the Fig’s. 1-2,

Fig. 1 illustrates the transfer of paint from the bulk reservoir (102) to the inlet tank (106) through feed pump 1 (104). A plurality of pressure sensors are provided at inlet and outlet of print head (112). The feed pump 1 (104) and bulk reservoir (102) are positioned away from the main unit to ensure convenience and flexibility. Subsequently, the paint is supplied to the print head (112) from the inlet tank (106) through feed pump 2 (108) and the print head inlet, dampers (126&128) and pressure transmitter (110). The print head inlet pressure transmitter (110) accurately measures the pressure at the print head (112) inlet manifold to maintain optimal meniscus pressure, which may vary depending on the type of fluid being used.

During the operation of the system, the recirculation print head (112) effectively removes any excess fluid from the print head (112) using the suction pump (116) through the suction pressure transmitter (114). The excess paint is then directed back to the bulk reservoir (102) for efficient recycling or future use.

The system consists of various components, wherein the flow of fluid starts at the input feed pump 2, which pushes the fluid towards the print head after passing through a filter and damper to ensure a clean and consistent flow.

The system focuses on maintaining optimal pressure within the print head. Pressure regulation is crucial to prevent issues like bubble formation or fluid drooling. Pressure sensors are strategically placed at the inlet and outlet of the print head to provide real-time feedback on pressure levels. This feedback enables precise control and adjustment of the input feed pump 2 to keep the pressure within the desired range.

After passing through the print head, the excess fluid exits through an outlet using suction pressure. This suction pressure facilitates efficient fluid collection and directs it back to the inlet tank for reuse, minimizing waste.

Additionally, the system considers the movement of the print head in different directions during the printing process. Changes in position can impact the pressure within the print head, potentially causing drooling or bubbling. To address this, the system incorporates pressure feedback from the sensors. By continuously monitoring the pressure levels and making real-time adjustments to the input feed pump 2, the system maintains a consistent meniscus pressure at the print head nozzles. This helps enhance print quality and prevent operational issues.

Overall, the system described aims to overcome challenges related to maintaining optimal fluid pressure within the Drop on demand (DOD) inkjet print head, ensuring a smooth and efficient printing process.

Fig. 2 illustrates the print head pressure regulation of desired range for optimal performance. The operating pressure range is maintained to avoid the formation of bubbles on recirculation side or drooling from print head. The pressure sensors are provided at inlet and outlet of the print head. The real-time feedback sensors provide data regarding pressure level, enabling precise control and inlet pump adjustment.

The movement of print head in X, Y and Z directions during printing process effects the pressure within print head. The supply system incorporates pressure feedback sensors and constantly monitors the pressure level and making real time adjustments to input feed pump 2.

The control unit of the supply system described is a feedback loop that utilizes pressure sensors, robot pose information, and a closed-loop PID control system to regulate and adjust the pressures across the print head.

The control unit considers the vertical height of the print head, which affects the atmospheric pressure at the printhead nozzle plate. Based on the robot's pose and the change in vertical height, the pressures across the print head (input pressure, Pin, and recirculation pressure, Pout) need to be adjusted accordingly.

The control signals of the pumps in the supply system are varied based on the feedback parameters. The pressure values across the print head are calculated using specific formulas, ensuring that they fall within the desired range. These calculated values of Pin and Pout are used to determine the duty cycles of the pumps through a closed-loop PID control system.

The control unit employs a Digital Signal Processor (DSP) to implement the feedback loop. The PID controller is tuned to maintain the pressures across the print head within the desired range, ensuring optimal performance. The control system is also designed to be robust, capable of handling environmental changes such as temperature variations or changes in the viscosity of the ink.

In summary, the control system described in the patent documentation ensures a continuous and consistent supply of ink for drop on demand inkjet print heads. By effectively regulating the pressures and incorporating a closed-loop PID control system, the system overcomes issues like drooling and bubbling, leading to improved print quality and performance, particularly in applications such as automobile paint printing.

The detailed working procedure of the system can be summarized in a step-by-step process:

Step 1 : Fill the bulk reservoir tank (102) with paint to be supplied to the print head (H2).

Step 2: Position the pressure sensors at the inlet and outlet of the print head (112) to monitor and regulate pressures within the range of -10 to +10kPa.

Step 3: Configure the plurality of pressure sensors to regulate the pressure at the print head (112) based on changes in vertical height.

Step 4: Transfer the paint from the bulk reservoir (102) to the inlet tank (106) using feed pump 1 (104).

Step 5: Supply paint to the print head (112) from the inlet tank (106) using feed pump 2 (108) and the inlet pressure transmitter (110). Step 6: Maintain a differential pressure between the inlet and outlet of the print head (112) by adjusting the operation of the feed pumps (104&108) based on feedback from the control unit.

Step 7: Apply the paint to the desired surface using the print head (112), which operates in X, Y, and Z directions.

Step 8: Remove excess paint from the print head (112) using the suction pump (116) and the outlet pressure transmitter (114).

Step 9: Return the excess paint to the bulk reservoir (102).

This continuous process eliminates the need for masking, minimizes material wastage and spillage, and promotes an environmentally friendly painting process.

Overall, the described robotic painting system and method offer a streamlined and efficient approach to painting, ensuring precise paint application, reduced material wastage, and a sustainable working environment.

The supply system, Pulse Width Modulation (PWM) pumps on both the input and recirculation sides of print head adjust the flow rate of ink to maintain a constant pressure difference. The input pressure is maintained within the range -10 to lOkPa. This ensures a consistent and stable pressure for delivering ink to the print head, resulting in improved print quality and reduced ink waste.

The present invention described controlled supply system for drop on demand recirculation inkjet print head which has a distinct design component, pressure regulation, and applications.

In terms of design and components, the present invention system focuses on regulating pressure within the print head and collecting excess fluid. It includes an input pump, filter, damper, pressure sensors, and an inlet tank. On the other hand, the CISS consists of ink reservoirs, ink tubes, modified ink cartridges or printheads, and air vents or valves. Its design facilitates continuous ink supply using gravity and pressure differentials.

Regarding pressure regulation, the present invention system utilizes pressure sensors at the inlet and outlet of the print head to monitor and regulate the pressure within a specific range. This ensures optimal performance and prevents issues like bubbling or drooling. In contrast, the CISS does not specifically focus on pressure regulation. Instead, it relies on gravity and pressure differentials to maintain a continuous/recirculation flow of ink, with the ink reservoirs positioned above the printer to facilitate gravity-assisted flow.

In terms of applications, the present invention system is specifically designed for drop on demand inkjet print heads, with a particular focus on applications such as printing paint on automobiles. Its design and functionality aim to maintain pressure and ink supply during movement, ensuring optimal print quality. The CISS, on the other hand, is a versatile ink supply system be used as an alternative to traditional ink cartridges in home and office printing environments. It offers extended printing capacity and cost savings.

Overall, while both systems provide continuous ink supply, they differ in their design, pressure regulation methods, and target applications. The present invention described system is specialized for drop on demand (DOD) inkjet print heads and focuses on pressure regulation, but it can also suitable as general ink supply system for various inkjet printers, emphasizing extended printing capacity and cost efficiency.

Sequence of steps followed by the program: Step 1: The control unit of the supply system is a feedback loop that takes in pressure sensors at the input and recirculation end, as well as the robot's pose.

Step 2: Based on the pose, the change in vertical height from the print head center affects the atmospheric pressure at the print head nozzle plate, resulting in the need to adjust the pressures across the print head (i.e., input (Pin) and recirculation (Pout)).

Step 3: The pressure values across the print head (Pin and Pout) are calculated using the following two conditions which is specific to the drop on demand print head used with inkjet supply system.

Pressure at first nozzle < ((Pin + Pout) / 2) - specific gravity of ink * gravity * vertical height < Pressure at last nozzle and

|Pin - Pout < (as per print head manufacturer (constant)) kPa |

Step 4: Calculate the error in the pressure readings.

Step 5: Based on the readings, tune the PWM using PID controller

TEST RESULTS:

Working Fluid: Isobutyl Propionate

Viscosity (MPa): 15

Density (g/cc): 1

Operating Temperature (°C): 25

Test Conditions:

Input Feed Pump (108) PWM%: varied between 37 and 100

Recirculation Pump (suction) PWM%: varied between 5 and 25

Input Pressure (kPa): ranged from 0.072 to 0.093

Recirculation Pressure (kPa): ranged from -0.02 to 0 Remarks and Observations:

Observations:

With lower feed pump 2 PWM% (37-40) and lower recirculation pump PWM% (5), there were pulsations and drooling.

Increasing the feed pump 2 PWM% (45-100) and recirculation pump PWM% (6-25) reduced drooling and pulsations.

At higher feed pump 2 PWM% (100) and recirculation pump PWM% (20-25), there were occasional pulsations and drooling observed.

Some tests showed few bubbles in the recirculation, but no significant issues were observed.

Overall, the test results indicate that adjusting the pump PWM% values and maintaining the appropriate pressure ranges can help reduce drooling, pulsations, and bubbles in the system. Fine-tuning the pump control parameters can lead to improved performance and more stable paint supply during the painting process.