Difference between revisions of "Statement of Work for the 100% engineering drawings"

Revision as of 10:51, 12 November 2007

Statement of Work for the engineering design of the Hall-D Tagging Magnets and Vacuum Chamber system

Draft v.2 (11/07/07)

This Statement of Work is to develop detailed engineering drawings and all required material calculations for the Hall D Tagging Magnets and Vacuum Chamber system based on the design goals stated in version 4 of 5/7/07 of the document entitled “Hall D Tagged Photon Spectrometer: Technical Description and Specification” [1] and the conceptual design drawings (on the 34% level) provided the Institute for High Energy Physics in Moscow [2]. The scope of this statement of work will be detailed in the following sections. A clear separation between the engineering design and fabrication is required according to the procurement rules of the U.S. Department of Energy (DOE). The contractor for this statement of work may in the future bid for the contract to manufacture the system, but this expectation is not a requirement.

The Hall D tagging magnets and vacuum chamber system includes the following parts:

1. Two dipole magnets including coils and cooling system
2. Vacuum box including flanges for thin windows and external supporting structures
3. Quadrupole magnet including coils and table support
4. Strongback support structure for the dipole magnets and the detector hodoscopes. The design of the hodoscopes themselves is not part of this contract.

The engineering design shall be performed in three stages. Stage 1 collects all of drawings that were produced for the 35% conceptual design and applies to them the revisions that were requested when these drawings were reviewed at Jefferson Lab in May, 2007 (see Addendum). Stage 2 entails a detailed design on the 65% level, including mechanical stress and magnetic field uniformity calculations. In stage 3, detailed drawings of all parts of the system are produced, such that these design drawings can directly be used to manufacture the parts.

A finite element analysis (FEA) must be performed for all parts that are subjected to strong forces. In particular, the goal of this analysis is to optimize the number and position of fasteners (bolts and brackets) holding the magnet yokes, pole shoes and vacuum box in place, and to optimize the rib structure which stiffens the vacuum box. The design drawings for the dipole magnets shall assume the upper and lower magnet yokes consisting of one single piece of iron each.

Calculations of the magnetic field in the quadrupole and two dipole magnets are required in order to complete the stress analysis. The contractor may chose to carry out these magnetic field calculations independently, or they may rely on the University of Glasgow to compute the magnetic fields based upon models provided by the contractor. The results of the stress analysis will be the basis for defining the machining and fabrication tolerances for the magnets and support structures.

The drawing models must be produced in 3-dimensional form using a professional CAD program. Layout and detail drawings will be in 2-dimensional form generated from the 3-dimensional models whenever possible. Input files used for stress analysis and field calculations must be delivered in electronic form. Jefferson Lab will provide a numbering scheme to facilitate their inclusion into the Hall D design database. Further details concerning interfacing with Jefferson Lab’s designing scheme will be provided.

This statement of work requires that deliverables be received and approved in 3 separate stages. In order to ensure that work remains on track, monthly phone conferences between designers and Jefferson Lab personnel / Hall-D collaborators are required. These meetings, together with the review and approval process at the completion of each contract stage, will be coordinated by a Tagger Design Coordinator to be designated by the Hall D group leader. The work on each stage must not begin until the deliverables from the previous stage have been received and approval granted by the coordinator. The transfer of funds for the ongoing design will follow upon this approval. The envisioned due dates for deliverables are:

1. February 29, 2008, for completion of stage 1;
2. May 31, 2008, for completion of stage 2;
3. September 30, 2008, for completion of stage 3.

Upon delivery the drawings will be reviewed by Jefferson Lab personnel / Hall-D Collaborators and reported to the contractor within less than one month. The due date for the completion of stage 2 is not negotiable due to an external DOE review in summer 2008.

Stage 1 – Revision of conceptual design drawings

This revision entails the collection and assessment of the drawings produced for the 35% conceptual design [2] in the light of the Hall D tagger specification [1]. Full compliance with the specifications described in reference [1] and the revisions, listed in the addendum, are mandatory for the completion of this stage. Jefferson Lab will provide drawings describing the interfaces to the upstream and downstream electron beamline (electron entry and exit ports), to the photon beamline, and to the tagger hodoscope. The following drawings are subject to this revision.

1. Top level drawings of the complete tagging spectrometer system including quadrupole, two dipole magnets, vacuum system and strong-back support.
2. Vertical section through a dipole showing how the pole shoes and yoke parts fit together.
3. Top view of a dipole showing the numbers, sizes and locations of the bolts required to hold the structure together.
4. Individual drawings of the pole shoes, top and bottom yokes, and back yoke, showing details of bolt locations and tolerances on all dimensions. Particular attention should be given to the tolerances on the relative alignment of the two dipoles and the vacuum-sealing lips on the vacuum chamber that mate to the pole shoes.
5. Individual drawings of the pole shoes showing the placement of the vacuum tensioning brackets and the coil support brackets.
6. Layout of the vacuum chamber showing how the top and bottom surfaces, the back wall and output flange are welded together. The input port, the photon beam exit pipe, and the main electron beam output ports shall be shown in their revised configuration.
7. Individual drawings of the top and bottom lids, and the back-wall of the vacuum chamber showing where the fixing holes for taking the vacuum tensioning brackets are located.
8. Top and side view drawings of the quadrupole magnet and its table support.
9. Top and side view drawings of the strongback support for the dipole magnets.
10. Drawings showing progressive stages of assembly and disassembly of the dipole magnets and vacuum chamber system, including temporary features which maintain the required alignment during this sequence.

Stage 2 – Engineering design at the 65% level

The engineering design of the dipole magnets shall be performed including FEA of the energized magnet. Special care has to be taken for the pole shoe design, the attachment of the vacuum box, and torques on bolts such they are not overloaded. The design drawings for the dipole magnets shall assume that the upper and lower magnet yokes consist of one single piece of iron each.

The engineering design of the vacuum box shall be performed including a FEA showing that the rib structure for stiffening the vacuum box is optimized to meet the specified requirements. Special attention should be paid to the degree of compression of the vacuum o-ring to ensure that it does not exceed the specified tolerances at any point during the assembly process or in the final configuration under varying amounts of current in the coils.

The drawings should show the markings on the pole shoes that are used to align them, and the procedure to be employed during assembly to transfer their coordinates to external references that enable the spectrometer to be properly positioned within the site-wide coordinate system in the tagger hall.

The engineering design of the quadrupole and strongback support structure shall be performed. The engineering design includes as well the table support for the quadrupole. A stress analysis must be performed to confirm that the strongback design is sufficiently rigid to maintain the required alignment of the magnets and vacuum chamber.

Stage 3 – Complete detailed engineering design

The complete engineering design of the Hall D tagger magnet and vacuum chamber system shall be performed. The design drawings from this stage must be sufficiently detailed and accurate that a firm other than the design contractor could manufacture the system from these drawings with no further documentation.

References

[1] Hall_D_Tagger_Spec_v4.doc (gluex document 821) GlueX_tagger_specification

[2] IHEP AutoCAD drawings 35%_drawing_by_IHEP_provided_in_April/May_2007

Addendum: Revisions to the IHEP drawings [2]

The following items were discussed upon review of the conceptual design drawings by IHEP and have to be corrected in the revision process (stage 1):

1. Top and bottom magnet yokes consist of a single piece of iron each.
2. The electron beam entry flange has to be positioned correctly (position from Yang's drawings or accelerator coordinate system?)
3. The electron beam exit flange has to be a large rectangular shape of 2" height and 6" width expanding towards the focal plane (interface drawing by Tim)
4. The exit pipe for the photon beam has to follow exactly the direction of the upstream electron beampipe. The photon beam pipe is directly connected to the vacuum chamber (no window).
5. The gap between vacuum chamber and pole shoes has to be sufficiently large to ensure the proper placement and contraction of the sealing o-ring.
6. ...