Abstract At the plant of Outokumpu Stainless Tubular Products AB in Molkom a wide range of butt weld fittings are produced. These are aimed mainly for the process industries and one of the products are ninety degree bend elbows in various dimensions. The elbows are made from stainless sheet metal and when formed to a tube they need to be welded along its inner radius. This is made by a pick and place type industrial robot working in a closed compartment. The assignment given by Outokumpu aims to investigate and suggest a new concept for a more reliable manufacturing process within the work cell. The cell consists of five main areas chronologically listed as passed by the elbow: · Automated, vibrating conveyor.· Fixture with the purpose to serve the robot with one elbow at a time, placed in the correct position.· Industrial robot to pick up the elbow and drag it along the welding head.· TIG inverter with a stationary welding head· A hydraulic press with a template of the final shape of the elbow corrects flaws. Almost every problem in the cell and defects on the products coming out of it can be traced back to the fixture and in some cases also to the robots pick up tooling. The focus of the task was therefore put mainly on those two areas. As the work proceeded Outokumpu chose to develop a new tool for the robot themselves which they did with good results. I chose to incorporate it into my study and change focus to the fixture instead. The problems and possible causes to them were identified and discussed with my tutor: The elbows fall incorrectly into or beside of the fixture. Fixtures are old and worn down. The elbows path between conveyor and fixture are somewhat out of control The smaller dimensions have room enough to slip past the fixture. Edges to be welded are to far from each other or badly shaped Commissioning time, some start up steps is more complex then they need to be. Some of the setting possibilities in the working cell are unnecessary and can be fixed instead. The positions of pick up and welding head are not really fixed in the robot software, these are reprogrammed every time elbow size are changed. · Various errors at weldingo Robot managed to pick incorrectly placed elbow Proposals to solve the above specified problems: All parts in contact with the elbows are to be made of harden able steel. A suitable one is C45E which can be casehardened to about 700HV. On the outer edge of the conveyer a support are placed to prevent excessive wear. The fixture is partially redesigned with a support to control the elbows path better. Guide arms with dual purpose are added. First they guide the elbow into the fixture and secondly they turn it to the correct angle towards the robot. Pins are used along with quick lock clamps to obtain faster and easier commissioning. The pick and place tool developed by Outokumpu are used.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kau-4628 |
| Date | January 2009 |
| Creators | Hinders, Fredrik |
| Publisher | Karlstads universitet, Fakulteten för teknik- och naturvetenskap |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | Karlstad University Studies, 1403-8099 |
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