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D2 interface follow up meeting (INFN)
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Description
The objective of the meeting was that INFN presents the current status of the conceptual assembly sequence of the D2 Short model.
CERN presented the current understanding of pending design items to be studied on the D2 prototype cold mass and its implementation plan.
April 25, 2016
Meeting Minutes
D2 interface follow up meeting (INFN.), 21-22/04/2016 (rev 1.0)
Participants:
INFN : P Fabbricatore – (PFE), S. Farinon – (SFN), R. Cereseto (RCO)
CERN: A. Foussat (AFT)
Distribution list: E. Todesco, F. Savary.
Introduction : The objective of the meeting was that INFN presents the current status of the conceptual assembly sequence of the D2 Short model. AFT to present the current understanding of pending design items to be studied on the D2 prototype cold mass and its implementation plan.
1 - D2 COLD MASS INTEGRATION presented by Arnaud Foussat
AFT addressed the D2 prototype cold mass design and integration pending issues, the schedule to resolve them. Some specific emphasis on the constraints related to the interface with the MCBRD correctors n the common cold mass.
LHe vessel shells assembly :
During the welding operation of the halve shells assembly it was confirmed that the design of D2 requires as low applied pressure as possible.
A01- CERN shall confirm what is minimum applied pressure required on the longitudinal welding press to perform the welding.
Longitudinal welding plane:
The current baseline foresees a welding in the vertical plane which would require a dedicated rotating tooling at 90 deg of the cold mass, some lifting tool with large aperture and some adapted lifting features interfaces.
The main reason why the welding is not planned in the horizontal plane is because of the permanent risk to burn the yoke inside the CM.
It was mentioned that the design would benefit of the presence of a cut slot (25 mm x 8 mm) which allows to protect the yoke and perform the weld in horizontal plane.
A02- INFN shall check what would be the impact of such a slot on the field quality.
Lifting interface
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The Short model weight is 2.5 tons and require standard lifting fixture onto top of cold mass. CERN to send drawing with dimension of lifting interface.
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The short model requires to be erected vertically for the cold test.
A03- CERN to send information on vertical lifting tool to see if it can be used. Alternative is to use eye bolts at extremities of handling tie rods.
Collar material
INFN confirmed that it is necessary that the collar material is same as for the series.
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Short model: The material of collar and yoke shall be available in September 2016. The cutting operation would start in February 2017.
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Prototype: The construction contract shall start in April 2018. The material of collar and yoke shall be available from June2018.
A04- CERN to send to INFN the Roxie B-h database for Cockerill iron
Coil dimension:
The dimension of the current coil CAD model at RT is 8034 mm with some provisional end plate of 50 mm thick to be compared with the allocated dimension on LHCLSXH__0010 layout drawing.
End Saddle material
SFN asked what could be the material specified for 30 MGy.
A05- AFT will inform INFN of potential candidate insulation material which can be used on D2 end saddles.
Fixed point:
AFT pointed out that the proposed central position of fixed point is causing issues of compensation on the QQS cryogenic side piping.
A06- Some assessment shall be performed to see if we can use the standard scheme of fixed point close to QQS.
Busbar routing and envelop cross section, splices
Aft presented the envelop 50 x 21 mm of the main 13kA main insulated busbars. The options of bus routing has been discussed, final decision shall be taken once further interface assessment is carried out at CERN.
Coil structure
INFN presented the new preload longitudinal structure relying on two central stainless steel rods ( OD: 30mm) and four external ones (OD: 25 mm). this update design allows to better support the coils end without bullet gages. The total nominal preload is 250 kN. The main contributor in the longitudinal stiffness is the collared coil pack in comparison with the tie rod assembly. The differential expected longitudinal elongation of coil during operation is about 1 mm.
The geometrical measurement of the coil shall be done under press at 70MPa.
The collaring operation targets an average stress of 90Mpa which relax down to 70 Mpa and reach 50 Mpa at cold.
The new design of collar section implies some spaces to be filled with non magnetic material at corners of the aluminum ring to respect the filling factor. The collar laminations packs are proposed to be 30 mm thick and the aluminum ring 60 mm thick.
In order to control the geometrical dimensions of the collared prototype coil some specification of deviation should be given in order of 0.3 mm/m.
As regard the collar material machining route, it was confirmed that the choice of fine blanking is to be selected for the prototype and the series unlike the short model which shall rely on wire cutting.
Elliptical to cylinder buffer piece:
An adaptation buffer piece made of stainless steel is designed to adapt form elliptical cold mass shape to cylindrical shell. It allows passage of handling tie rods. This piece shall be delivered at CERN on cold masses already installed. Some centering alignment features on top of vertical yoke split shall be designed by INFN and included to center the adaptation piece. If these pieces are pre installed on the coil before it is shipped to CERN, some interface with the lifting equipment shall be devised, for instance through slings attachments.
Quench heaters
The technology used on MB dipole will be chosen with interconnection wires to be accommodated at the end plates
Cold tubes
The short models shall be equipped two tubes to allow to perform the magnetic measurements
Electrical quality control tests
It was explained that the test voltage are derived from the fault voltage which is around 250 V to ground on D2. This will be documented by PFE once the fault analysis report is complete. AFT illustrated the standard electrical quality control performed on LHC dipoles which will be specified onto the short model and prototype technical specifications.
External leads
Conceptual design of exit jumper connections were presented by RCO. Some OFH copper is used to stabilized exit leads embedded into sliding protective G10 cassettes.
A07 -CERN to send standard design drawing of the external leads jumper connection to compare with present proposal onto the D2
Schedule
AFT presented the plan for integration of D2 cold mass, the need for cold mass drawings, the cryostating design. He highlighted the schedule to order the material starting from end 2016 to cover the needs of D2 and MCBRD short models, correctors prototype and then series needs.
PFE pointed out that the D2 series production is not committed yet.
The current schedule of parallel series production could be
challenging if the construction of the prototype will not reflect the
final design in every aspects. AFT mentioned that it would be important to be ready for next Cost and Schedule Hi luminosity review in October 2016 with a consolidated strategy.
A08- This matter will be discussed with WPs and Hi lumi project management.
CAD exchange
RCO informed that the CAD files are generated with Pro-engineer package which can be exchanged to CERN through IGS, STP formats readable by CATIA.
2- CAD ASSEMBLY SEQUENCE OF SHORT MODEL presented by Roberto Cereseto (INFN)
RCO presented the sequence of fabrication of D2 coils, the collaring phase the assembly of the two aperture through alignment keys. The insertion of half yoke around collared coils is performed under press to close the functional mid plane gap of 0.12 mm. The insertion of longitudinal C-clamps is followed by the longitudinal welding of a top stiffening bars holding the assembly. AFT pointed out that the space available to access to weld and guarantee quality should be checked. The handling tie rods compatible with the new collars geometry has been introduced. A conceptual design of leads external jumpers was presented attached to the end plate.
3- VISIT OF LHC DIPOLE MANUFACTURE TOOLING AT ANSALDO PREMISES:
A visit was organized by R. Marabotto to see what is the status of the remaining tools which were used on the production of LHC dipoles.
Amongst the operational tooling stored, a 6 m long curing and collaring press is available with its hydraulic units and control units.
One fully equipped winding machine is available. In terms of measurement, the AC mole magnetic measurement and the E modulus module equipments are also operational.
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