RIA Robotic Engine Deburring Article - December 2004

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Engine Deburring System Focuses on Flexibility and Expansion

During Spring 2003, Genesis Systems Group, LLC., was asked by one of their best robotics customers to work on a custom robotic deburring system. While the majority of projects undertaken at Genesis focus on welding processes, their designers and engineers are experienced in engine deburring and cosmetic weld finishing automation and rose to the challenge to successfully complete this system.

The robotic system for the project was designed to work with engine blocks having a variety of features and areas to be deburred. The engine blocks ranged in size from four to five cylinders, however, the system was designed with the ability to work with blocks having up to six cylinders. It was then integrated into an existing powered conveyor line falling between the honing and finish washing operations and networked with the customer's manufacturing computer. The ultimate cycle time goal for the operation was 124 seconds (2.1 minutes) per block in order to keep pace with the planned future production requirements of the line. However, the initial production volume was lower and will ramp up over time as the speed of the line is increased.

Phase I: Research and Development

At the beginning of the design process, a model block was created to simulate the deburring process. Acceptance levels and expectations were established to serve as a baseline for each block going through the process. Due to the controlled machining processes prior to deburring, engine blocks entering the robotic system were deemed consistent, displaying little variation in the pre-deburred edges from one block to another. With the assistance and input from Osborn Brush representatives, a variety of deburring brushes were tested manually in order to gain a thorough understanding of their function and the time needed for them to work properly. Numerous programs and processes were used to examine multiple variables, including brush type, brush diameter, brush grit, brush wear, pressure, speed, and coolant needs.

Phase II: Deburring Process

Each engine block entering the robotic system for this application requires deburring on all six sides. The deburred areas include entry and exit edges of numerous size holes. Some of the engine block holes are blind, while others are through holes, requiring deburring at both the leading and bottom edges. In addition, edges at the intersection of machined and cast surfaces, as well as cross-drilled holes in the lifter bores are included in the process.

Once all of the surfaces, cylinder bores, pump bores and oil holes on an engine block are deburred, it is picked up and the completed block is returned to the conveyor line. Upon completion, the sharp edges of the engine block surfaces have been rounded and thinned, and the loosely attached metal flakes have been removed. The rounding of sharp edges will help prevent cuts during assembly, while the removal of the metal flakes will prevent the blocks from contaminating the oil and oil filter during normal engine operation. From this point, the block is ready to proceed to the finish/washing operation. The success of the deburring process was determined by conducting multiple tests by examining an acceptably removed burr or sharp edge through finger touch, rag drag, cotton drag or boroscope.

Equipment

This application utilizes a two-robot work cell with the flexibility to add an additional robot as production needs of the system increase. The robots for the system have weight capacities of 175 kg and 225 kg. Robot one (a pick and place robot) was designed to be responsible for all of the material handling and positioning requirements of the engine blocks within the work cell. This robot picks up the raw engine blocks from the conveyor line and places them in the work cell using a pneumatic gripper. In addition, it provides all repositioning throughout the deburring process. Through sensors in the gripper, the system is able to adjust to the engine block size accordingly. While the gripper is currently programmed to work with four and five cylinder blocks, it is designed to have the ability to work with six cylinder blocks as well when production needs change.

The second robot is equipped with a 15 hp spindle motor containing an automatic tool changer. With the assistance of the automatic tool changer, robot two handles the deburring processes through the use of a Pushcorp servomotor with an automatic collet that is incorporated with an Active Force Device. The system includes the ability to exchange eight different tools and control the force and speed for which the tools are used, thus allowing the use of the appropriate abrasive media on each edge. The control system allows the ability to edit these parameters from a touch screen panel located on the main operator console at the front of the cell, and also monitor the deburring servo- motor speed, temperature, and current. Handshaking signals between the robot controllers enable the robots to communicate interference situations.

Both robots included in the work cell are fully "dressed" and have the ability to provide coolant to the brushes. This is done through a pan and grating system placed as its floor to collect and re-circulate the coolant. In addition, the system includes nine-foot sealed fencing to help prevent coolant from escaping. Both the pan and grating system and the sealed fencing were designed and built by Automation Guarding Systems.

The tooling for the system integrates two engine-block holding fixtures for the deburring robot, which includes one nest per table design, a part-present sensor, and pneumatic clamping. The tooling included for the brush deburring station provides two air motors with bearing guides and tooling adapters, one sliding motor base with prox sensor to indicate an incomplete stroke, and two solenoid valves.

Conveyor Line Integration/Networking

Critical to the success of the project was the ability for the robot system to be integrated and networked with the existing conveyor line to provide a seamless flow between the honing, deburring, and finish/washing operations. To allow the deburring system to have control over a segment of the conveyor line, signals are shared between the system controller and the conveyor controller. This enables the deburring cell to bypass or mute conveyor signals, allowing the engine blocks to be picked-up or placed without causing unexpected movement on the conveyor.

Part of the integration of this system included networking with the factory's manufacturing computer. To ensure that quality is maintained to the highest level, each roughcast engine block is consistently labeled with a barcode before it can enter into the machining area. As it passes through each operation, the manufacturing network system tracks the processes that have been completed for each block. As a block enters the deburring work cell, the barcode is scanned, and the information is sent to the system process controller. The code is then sent via Ethernet to the factory's main computer to ensure that all of the previous processes have been completed. If the correct last operation number is received by the system controller, the pick and place robot is allowed to move the engine block into the cell. If the last operation number does not match, an error prompts the operator to bypass the block, rescan the barcode, or allow the block to enter into the deburring cell.

From the barcode, the number of cylinders included on the block is determined and the appropriate robot programs and tools are selected. After the engine block is placed on one of the two fixture tables, the pick and place robot sends a start signal to the deburring robot, allowing it to run through its assigned program. The pick and place robot returns to its home position where it waits for the signal to pick up the next engine block from the conveyor.

After the deburring robot completes its cycle, it sends a signal back to the pick and place robot to prompt it to return to the fixture table and retrieve the finished engine block. Before the pick and place robot places the engine block on the exit conveyor, it completes the deburring process by holding the block in front of a deburring table. At this station, pneumatic motors rotate two long, thin brushes as they push through the oil passages that run the length of the block. This is done to clear away or break loose any remaining metal chips.

After the engine block is placed on the exit conveyor, the system process controller relays the bar code information back to the manufacturing network system and waits for approval to release the engine block to the next operation.

Conclusion

The custom deburring project has successfully accomplished the goals set forth by the customer. The system is able to effectively round out the sharp edges contained on the engine blocks. This helps ensure safety and removes the existing metal flakes that could potentially contaminate the oil and oil filter during normal engine operation. In addition, the customer has a system with flexibility built into the design and programs to accommodate for their future production needs. Their system works seamlessly with their existing conveyor line and barcode system and they will be able to utilize the work cell for various size engine blocks as they are introduced.

About the Author and Contributor

Dave Bergmann
Dave Bergmann is an Applications Engineer at Genesis Systems Group. He has 17 years of experience in robotic welding integration and custom automation. He received his Bachelor of Science Degree from Southern Illinois University in Electronic Systems Technology and his Associates of Applied Science Degree from Clinton Community College, Clinton, Iowa in Electronics Engineering Technology. He is a certified AWS Welding Inspector and has received a patent for Robot Alignment Apparatus & Method of Operation.

John De Leon
John De Leon is a Project Manager at Genesis Systems Group. He has seven years of experience in robotic welding and custom system integration. He has a Bachelor of Science degree in Mechanical Engineering from Iowa State University and has worked on a variety of projects at Genesis, including deburring and custom automation systems. He is currently working with customers in the United States, Mexico and Canada.

About Genesis Systems Group

Genesis Systems Group is an industry leader in the design, manufacture, and building of robotic systems for welding, cutting, and custom applications. Founded in 1983, Genesis is the largest robotic arc welding work-cell integrator in North America. The company has installed more than 2,000 robotic welding systems in more than 36 states and seven countries.