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Challenges in Girder Fabrication: Achieving Tolerances and Machining Process

This workshop discusses the difficulties in achieving tolerances in girder fabrication and presents a new machining process that improves precision. It covers the main parts of the girder, the properties of aluminum used, and the step-by-step process of the new machining technique.

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Challenges in Girder Fabrication: Achieving Tolerances and Machining Process

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  1. Girders fabrication: Difficulties to achieve tolerances and machining process Igor Madariaga (ESS-Bilbao) 13 September 2011 DTL mini-workshop, CERN

  2. Outline • Introduction to DTL • Girder´s properties • Girder´s new machining process • Improvements of the new machining process

  3. Introduction to DTL • Main Parts of the DTL • Drift tubes • Tank • Girder

  4. Introduction to DTL • Parts • Drift tubes • Tank • Girder • Drift tubes

  5. Introduction to DTL • Parts • Drift tubes • Tank • Girder • Tank

  6. Introduction to DTL • Girder Spend time machining the girder avoid post - alignments

  7. Girder´s properties • Girder main functions: • Fix the position of the DTs with high precision • Material • Aluminum EN AW-5083 H111 • Dimensions • 1924 x 150 x 177 mm • 2 machining process • The old one does not achieve the tolerances between critical holes

  8. Girder´s new machining process • Main parts of the process • Rough milling • Leaving 5 – 6 extra mm for each dimension • Stress releve • Thermal treatment • Pre finish • Finish

  9. Girder´s new machining process • Rough milling • Machine: Centro mecanizadoSoraluce • Be sure not to introduce any linear or torsional deformation Test with dial indicators • Avoid heating of the milling zone • Use 4 supports and 4 clamps Large quantity of coolant

  10. Girder´s new machining process • Definition oh holes and faces Stamp holes Top face Girder key Cooling holes Left/right face Hoist points Fit into the tank (Girder key) Bottom face

  11. Girder´s new machining process • Rough milling • Square the part to obtain parallel faces • Drill stemp and cooling holes (ø50 and ø40) • Mill girder key(80) Old machining process

  12. Girder´s new machining process • Pre finish • Machine: Mandrinadora SACEM-530 • Precision: +/- 0,01mm • Control room temperature +/- 0,5° C to avoid thermal dilatations. • Be sure not to introduce any linear or torsional deformation Test with dial indicators • Use 3 supports and 3 clamping points (L/5 and in the middle)

  13. Girder´s new machining process • 3 supports and 3 clamping points supporting the part in top face • Finish-mill ø35 pocket • Tap M-12 screw holes • Finish-drill ø40 holes cooling holes • Pre-Finish face B Right face Top face Hoist holes First low tolerance dimensions After high tolerance dimensions Old machining process

  14. Girder´s new machining process • Turn table 180 ° • Finish-mill ø35 pocket • Tap M-12 screw holes • Finish-drill ø40 holes cooling holes • Pre-Finish face C Left face Top face Hoist holes

  15. Girder´s new machining process • 3 supports and 3 clamping points supporting the part in right face • Rough-mill 15k6 to 15,5mm • Rough-mill 80h6 to 80,5mm • Finish-drill ø12,5 holes • Tap hoist drills M-12 • Finish-boring ø49,5 • Finish-boring 50 H7 • Pre-finish face A Bottom face Right face • Girder key • Hoist holes • Stamp holes Old machining process

  16. Girder´s new machining process • Turn table 180 ° • Finish-mill ø42 pocket • Rough-drill ø10H7 to ø8 • Finish-drill ø14 holes • Finish-mill ø35 pocket • Tap M-12 screw holes • Finish-mill ø70 • Finish-boring 50 H7 • Pre-Finish face D • Insert the bushes Top face Right face • Hoist holes Old machining process • Stamp holes

  17. Girder´s new machining process • Finish • Machine: DIXI 5S • Dimensions: • Axis X 2m • Axis Y 2m • Axis Z 1m • Precision: • Flatness 0,002 – 0,003 mm / 2 m • 0,001 mm distance between holes • Turn 0,0002 °

  18. Girder´s new machining process • Finish • Control of the temperature of the room +/- 0,25° C to avoid thermal dilatations. • Be sure not to introduce any linear or torsional deformation Test with dial indicators • Use 3 supports and 3 clamping points (L/5 and in the middle)

  19. Girder´s new machining process • 3 supports and 3 clamping points supporting the part in top face • Finish-mill face right face to high tolerance Reference face • 3 supports and 3 clamping points supporting the part in right face • Finish-boringø10 H7 • Finish-mill face D Right face Top face Top face Right face

  20. Girder´s new machining process • Turn table 180 • Finish-mill 80 h6 • Finish mill 15h6 • Finish-boring40 H6 and 39,8 H6 Bottom face Right face • Girder fit • Stamp holes

  21. Improvements of the new machining process • Better machine, with better tolerances • Temperature control: • Better control of the room´s temperature • Better temperature control in the milling zone Really important to avoid thermal dilatations • Different machining process • Don´t leave the small drills for the final

  22. Girders fabrication: Difficulties to achieve tolerances and machining process Igor Madariaga (ESS-Bilbao) 13 September 2011 DTL mini-workshop, CERN

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