Produktions- och konstruktionsanalys av acceleratortekniska komponenter

Abstract

A particle accelerator consists of a large number of components, which among other things includes several acceleration modules, which consists of one or several cavities. A cavity is a complex and essential part in the accelerations process and is usually made of oxygen-free copper (OFC) or niobium. These two materials are special when it comes to metal cutting, it´s hard to find information about these materials in general but also how to machine them.
The goal with this master thesis is to perform a construction and productions analysis for a cavity to find out how it can be produced in an easy and simple way. An essential part of this thesis is to find out information about OFC and niobium and how to machine them.
To examine how to improve the production of the cavities a systematic development method was developed. In this method all the different production stages were listed; what kind of machining, tolerance requirements, function controlled or production critical operation. This was made to find out which operations cannot be changed because of the functionality and which operations or tolerances that can be changed. Furthermore examples were given of different operations that can be changed to make the cavity easier to produce. This method can also be used for other components than the cavity.
Selection of cutting data and tools that were used in the experiment were based on literature studies for the materials. One of the performed experiments was steps with increasing feeds while cutting depth and speed remained constant, cutting forces were measured during the experiment. In another experiment surface finishes were measured, for OFC cutting speed and feed varied while cutting depth was constant. For the niobium experiments it was only the feed that varied. These experiments were repeated for different kinds of tools were the geometry of the tool differed or if the tools were coated/uncoated carbide or diamond tool.
From the results of the experiments a cost analysis was performed for a cavity. The time it takes to manufacture one cavity is calculated with the cutting data that are based on the results which satisfies the requirements of the surface finish. From the calculated manufacturing time and other calculated or estimated variables we calculated the manufacturing cost for one cavity.
Our conclusions from the results were that all of the tools from the copper experiments can be used to achieve a surface finish of Ra 0.8 μm or better which is a requirement for the cavity. The tools that showed the best result were the uncoated carbide tools. Calculated cutting resistance that is based on the measured cutting forces from the experiment seemed to be surprisingly high, which can have connections to the ring of material that the tools pushed ahead of itself during the operation. From the results from the niobium experiments our conclusions are that it´s hard to achieve a good surface finish because of the adhesion of chips on the workpiece. There was a big variation in the measured Ra values for the tools with a nose radius of 0.4 and 0.8 mm. The best achieved Ra average value was 0.78 μm with the tool that had a 1.2 mm nose. Calculated cutting resistance was high for the niobium, similar to the OFC cutting resistance.

• author: Andersson, Anders and Olsson, Mike
• supervisor: Jan-Eric Ståhl; Claes Fahlander; Volodymyr Bushlya; Fredrik Schultheiss
• organization: Production and Materials Engineering
• course: MMTM01 20131
• year: 2013
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• report number: CODEN:LUTMDN/(TMMV-5259)/1-77/2013
• language: Swedish
• id: 4053783
• date added to LUP: 2013-09-18 15:12:08
• date last changed: 2013-09-18 15:12:08