The client of the project group is Airborne, which is a company that provides composite solutions/services to aerospace, maritime and automation problems. The main function of airborne is to manufacture composites.
Sheets of carbon fibre are delivered to the company in different shapes. On both sides of these sheets a layer of protective foil is applied. This foil differs on both side. Before the sheets can be handled, these foil layers have to be removed. This takes a lot of time when done by hand.
The assignment is to create a system that automatically removes the layers of protective foil. The sheet cannot be damaged during the process. In the result, it will be possible to insert a sheet into the system by hand, the system will remove the foil layer and the sheet can be taken out of the system by hand. The foil will be discarded.
- The system can handle different shapes of sheet.
- The sheet may not be damaged.
- The minimum speed of the process has to be equal or higher than the speed of a person removing the foil.
- The sheet has to be checked to see if the entire foil layer has been removed.
The concept that is chosen is based on the principle of “grabbing” the foil with a vacuum plunger and pulling it of the prepreg.
The ‘end of arm tool’ consist of one compliant vacuum plunger and one pneumatic gripper. The setup consist of an aluminium and wooden plate with two build in vacuum plungers, camera linked to vision software and a light resistance sensor.
A piece of prepreg is placed on the aluminium plate. The camera takes a picture from above and through the vision software the location of the prepreg is found. With the use of the vacuum plunger on the ‘end of arm tool’ the robot moves the prepreg over the build in vacuum plungers which will hold the prepreg in place. The robot (still holding on to the sheet) moves away and pulls of the upper layer of foil. Because the build in vacuum plungers take a hold on the bottom layer of foil the corner of the prepreg will “curl” up. The sensor will detect whether or not the prepreg “curled” up enough. If it is enough the robot will position the pneumatic gripper on the ‘end of arm tool’ and grab the prepreg. The robot will now move away, pulling of the prepreg from the bottom layer of foil and position the prepreg outside of the system for further processing.
The design is shown in the following pictures. You can see the ‘end of arm tool’ as well as the entire setup.
Results and conclusion
The results of the tests that were run showed that the principle works quit well. Yet several problems surfaced. The main problem being the vision software. The software with which was worked (In-sight explorer) is not sufficient enough. Shape/corner detection has been the most important part of the project, but with the used software this could not be detected precise enough. Squares and rectangles could be detected well. Also some shapes that didn’t deviate to much from a square worked as well, but those formed the limit.
The second problem was the speed with which the process was carried out. The robot that was used (a universal robot) did not fit the requirements. When the speed was turned up, it resulted in error messages that showed the robot was not able to perform the movement at those speeds. This slowed down the process drastically.
When the results are compared with the requirements there can be concluded that not all requirements have been met. Though the results to meet the requirements can be achieved with this concept.
The system is able to move the foil from two sides, this means that this requirement and even the wish set for this project are met. Also the following requirements have been met; removed foil needs to be stored, the sheet may not be damaged and the sheet has to be checked to see if the entire foil layer has been removed.
The removed foil can be placed wherever needed, the sheet is not damaged by the proceedings and during the process the prepreg is checked to see if al foil has been removed.
Two requirements have not been met; The system can handle different shapes of sheet and the minimum speed of the process has to be equal or higher than the speed of a person removing the foil. To still achieve the desired results it is recommend to use different vision software and to use a different robot. If equipment is used that is not limited in the way the current equipment is, this principle/concept can still be used to meet all the requirements.