First D2 cold mass engineering follow up (Video Conference)

Thursday 3 Mar 2016, 08:00 → 18:00 Europe/Zurich

CERN

- INFN - CERN discussion on current mechanical design of D2 dipole cold mass.

- Global review of the manufacture pending aspects related to collaring and yoking process.

- Plan for next meeting dedicated to mechanical design and assembly steps

D2-Shell INFN 2016-03.pdf

D2-Shell INFN 2016-03.pptx

D2 short model follow up meeting INFN-CERN (Video Conf.) – 03/03/2016 (rev 1.1)

Presents: P. Fabbricatore - PFE (INFN), S. Farinon - SFN (INFN), A. Foussat - AFT (CERN)

Distribution list: E. Todesco, F. Savary.

1. Yoke geometrical Shape: PFE presented an overall presentation the last case study of optimised iron yoke shape compatible with magnetic multipoles. The best proposed compromise shape is an elliptical shape combined with a filler structural material between yoke and cylindrical shell to be designed by CERN. The new current dimension of the elliptical yoke is confirmed by PFE at M 614 x m 544 mm

2. Assembly gap during yoking: SFN confirmed that the vertical assembly gap between yoke halves is 0.6 mm per side at room temperature and that at operating temperature 1.9 K this gap should be not less than around 0.1 mm (positive tolerance is allowed). What is important design requirement is to keep and control pressure and contact on horizontal plane sides of each collared coil.

3. Yoke assembly pressure: the final preload pressure shall be determines once the material of yoke will be confirmed.

4. Busbar layout : AFT asked PFE for the 2D cross section in order to propose location and design for busbars passage compatible with the circuit layout; 3D Cad models are been updated at INFN with latest yoke modifications;

5. CERN Shell Material: Aft confirms that the usual material used on shell is austenitic stainless steel, grade 316LN. kg. onto the 11T dipole the two shells form a shrinking cylinder, which sees after welding around the yoke a design azimuthal stress of about 200 MPa. The azimuthal stress increases to about 300 MPa after cool-down to 1.9 K. D2 does not need to see large preload during shell assembly and the value of pressure shall be confirmed once the yoke material is finalised.

6. CERN collar material: PFE confirmed that for D2 design point both solutions involving YUS 316S (Nippon Steel)
   or KHMN (by Kawasaki steel now JFE) are fine. Between the two options, KHMN is highly preferable because the thermal contraction from 300 K to 4.2 K.

As a reminder, the standard MB used the Nippon Steel YUS-130S is an austenitic steel grade with high content of Carbon, (CTE : 2.6e-3). This allowed Nippon Steel Company to avoid a costly refining process, with the counter-part of being a process difficult to master in order to ensure the quality of the grade. This is considered a valid solution for the quantity of steel that was required for the production of the LHC dipoles ( Enclosed Nippon Steel properties).

For the volume required for our application,  in case of storage shortage at CERN, European manufacturers could probably propose grades that are produced through electric furnaces and AOD decarburization converters which will undoubtedly impact the production cost which shall be confirmed when firms are contacted. The route of procurement, the steel grade shall be confirmed by CERN once the procurement plan and needs are clarified with INFN.

1. Aluminium 6000 series sleeve: the depth of unit ring is 50 mm and the assembly either welded or coupled, to be confirmed once it is under discussion with industry.

2. Short model test schedule: PFE confirmed that the short model 1.5m is planned to be delivered to CERN for test by end 2017.

3. D2 dipole envelop dimensions: PFE shall confirm in two weeks of the cold mass with the connections in order for CERN to check integration of dipole into the sector

Actions items:

1. AFT to check availability of standard collar laminations steel material at CERN and check with INFN the procurement needs and plan up to the D2 dipole series. ( Week 12)

2. CERN to initiate design of filling material with a plan of analysis by CERN or INFN to check the compliance with final shell assembly and coil operation.  (Week 15)

3. A dedicated CERN-INFN meeting to D2 mechanical assembly shall be organised at INFN premises to review the details of mechanical D2 design and analysis. The assembly steps and final C clamps installation with the welding of longitudinal bar shall be discussed against tooling and PED code requirements. ( to be organised by mid April)

Best regards, Arnaud Foussat