Removing material from curved, round, or irregular surfaces creates many process challenges that need a special touch. Material removal applications such as gate grinding, filing, polishing, and others depend heavily on manual labor and take skill and experience to execute correctly. Because of their nuance and complexity, material removal operations like these seem “impossible to automate”.
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Sponsored by the Advanced Robotics for Manufacturing Institute (ARM), a group of engineers at The Robotics Institute of Carnegie Mellon discovered a way to tackle two of these challenging material removal operations in one solution. Their team included research and development experts from Siemens Technology as well as application guidance and support from Yaskawa. Together, these automation experts devised a breakthrough system that uses robots to remove weld beads from inside a tube.
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Material removal operations are quintessential to a variety of industries and range from very light finishing to heavy gate removal. Some processes are relatively simple, while some parts require a variety of tools and techniques over many hours to achieve the desired finish. Traditional material removal methods commonly utilize manual labor with hand tools, are prone to variability and quality inconsistencies, and put employees at risk of injury. Manufacturers can reduce costs and cycle times while increasing employee safety dramatically from automating these processes.
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Robotic material removal processes are increasing in adoption throughout a variety of industries. This is happening because technology is becoming more accessible while also becoming more flexible. We have more tools and techniques to overcome manufacturing challenges than ever before, and robots are becoming more affordable as well. With these advancements comes an opportunity for innovation of processes and techniques to produce safer solutions that are efficient and adaptable.
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Integrated compliance is one innovation that enables more precise automation of material removal tasks. Compliance can be either passive or active and allows a robot using a tool to respond to changes in the work surface in real time. Passive compliance is simple, like incorporating adjustable pneumatic pressure into the robotic tooling to adjust for part variation. Active compliance systems are more complex and provide specific force control in situations where processing requirements need to be exact.
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Lead by Changliu Liu, Assistant Professor at The Robotics Institute, a research team of students and engineering professionals developed an efficient robotic weld-bead removal system. Their objective was to produce a system that was not only safe and efficient, but also cost effective. The automatic weld-bead removal system they developed runs autonomously and can remove material quickly and effectively from tube-shaped welded parts.
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The team designed a fully-automated, active compliance system that was able to successfully locate, measure, and remove the weld bead from the tube’s interior and verify process completion. Their system included external vision technology to identify the weld bead first. Once located, the multi-axis feedback from an ATI Force/Torque (F/T) Sensor enables the Yaskawa arm to measure and react to the weld-bead, determine the correct amount of pressure to apply, and remove the bead with the cutting tool. Finally, a profilometer verifies that the removal meets specifications.
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In this application, the ATI F/T Sensor plays a pivotal role: it provides a comprehensive profile of the force and torque loads within the process for data analysis, and facilitates active compliance of the cutting tool on the work surface. With the force sensor, this robotic system becomes dynamic as it uses force feedback to detect, assess and grind the weld bead, while monitoring and adjusting the cutting force in real time. Integrated compliance, whether active or passive, makes programming robotic applications easier and produces a consistent finish despite variations in the part or path.
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For industrial manufacturers who must remain flexible to their customers’ demands, an affordable adaptable robotic cell is ideal. Together the Yaskawa robot, ATI’s Force/Torque Sensor, and modeling software can quickly and easily measure and remove a weld bead from an interior curve. The weld-bead removal system minimizes safety hazards, decreases cycle times, and improves overall process quality. The active compliance system provides a closed-loop process for maintaining and adjusting force control to ease programming efforts and ensure the desired result is achieved. Output quality is more consistent with this new system, but that is only part of the benefit to users. modeling software can quickly and easily measure and remove a weld bead from an interior curve. The weld-bead removal system minimizes safety hazards, decreases cycle times, and improves overall process quality. The active compliance system provides a closed-loop process for maintaining and adjusting force control to ease programming efforts and ensure the desired result is achieved. Output quality is more consistent with this new system, but that is only part of the benefit to users.
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The weld-bead removal system actually learns to improve based on the data it collects over time, which makes it very easy to program new parts and shapes. Low-volume, high-mix manufacturers want solutions that support the flexibility they need to stay competitive. The active compliance system streamlines the challenges of programming and executing heavy material removal and irregular shaped parts safely and efficiently, with room to grow. Projects like this one strike at the very core of ARM’s mission-which is to strengthen manufacturing through innovation.
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ATI’s F/T Sensor provides high-resolution measurements in real time and enables active compliance to allow the robot to maintain constant force on the part features. This ensures both a consistent finish and optimal cycle times, which can help manufacturers, streamline costs and increase productivity. In addition to Siemens, Changliu hopes to see this process implemented by other manufacturers in the metal fabricating industry in the near future.
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For more information about ATI's Force/Torque Sensors, click here!
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To watch a YouTube Video about this project, click here.
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To learn more about research efforts at the ARM Institute, click here.
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