1.-20. (canceled)
21. A method of manufacturing a press-molded product using a preform comprising a pair of spaced side walls connected by a connecting wall, the preform having a prearranged portion with a cross sectional thickness and a protrusion, the method comprising:
pressing the preform within a mold cavity formed between a die portion and a punch portion received within the die portion, the cavity having a cross sectional thickness when the punch portion is fully received in the die portion that is greater than the cross sectional thickness of the prearranged portion; and
increasing the cross sectional thickness of the prearranged portion by compressing the protrusion to flow material of the protrusion into the connecting wall and at least one of the side walls.
22. The method according to claim 21, wherein the protrusion increases a cross sectional periphery of the preform along the prearranged portion, the step of increasing the cross sectional thickness of the prearranged portion further comprising:
reducing the cross sectional periphery of the preform along the prearranged portion until it is substantially the same as a cross sectional periphery of the preform adjacent the prearranged portion.
23. The method according to claim 21, further comprising:
arranging the preform over the punch portion;
arranging the die portion about the punch portion to create the mold cavity, such that a gap formed between the punch portion and the connecting wall and first portions of the side walls adjacent the connecting wall is greater than a gap formed between the punch portion and second portions of the side walls opposite the connecting wall;
supporting the second side wall portions by the punch portion and the die portion; and
pressing-in the connecting wall and first portions of the side walls toward the punch portion using the die portion to bend a center portion of the connecting wall toward the punch portion.
24. The method according to claim 23, further comprising:
restraining a bending degree of the connecting wall by supporting the center portion of the connecting wall during bending.
25. The method according to claim 24, the step of restraining further comprising:
positioning a supporting member within a space between the punch portion and the connecting wall to contact and support the center portion of the connecting wall after bending of the center portion begins; and
retracting the supporting member toward the punch portion while supporting the center portion of the connecting wall using the supporting member during bending of the center portion.
26. The method according to claim 21, wherein the protrusion protrudes from a distal second side wall portion opposite the connecting wall, the step of pressing the preform further comprising:
arranging the preform over the punch portion, such that the protrusion contacts a contacting surface extending radially from the punch portion and spaces the second side wall portion from the contacting surface;
bending the connecting wall by contacting the connecting wall with the die portion; and
guiding a corner portion connecting a first portion of the side wall opposite the second side wall portion and the connecting wall while pressing the first portion of the side wall with contacting surfaces of the punch portion and the die portion.
27. The method according to claim 21, wherein the protrusion is a bulge protruding from the connecting wall, such that the protrusion increases a cross sectional periphery of the preform along the prearranged portion, the step of increasing the cross sectional thickness of the prearranged portion further comprising:
reducing the cross sectional periphery of the preform along the prearranged portion until it is substantially the same as a cross sectional periphery of the preform adjacent the prearranged portion by flowing material of the protrusion into at least the pair of side walls.
28. The method according to claim 27, the step of pressing the preform further comprising:
arranging the preform over the punch portion, such that distal second side wall portions opposite the connecting wall contact a contacting surface extending radially from the punch portion.
29. The method according to claim 27, wherein the protrusion further protrudes from a distal second side wall portion opposite the connecting wall, the step of pressing the preform further comprising:
arranging the preform over the punch portion, such that the protrusion contacts a contacting surface extending radially from the punch portion and spaces the second side wall portion from the contacting surface.
30. The method according to claim 21, wherein the protrusion is a bulge protruding from a side wall, such that the protrusion increases a cross sectional periphery of the preform along the prearranged portion, the step of increasing the cross sectional thickness of the prearranged portion further comprising:
reducing the cross sectional periphery of the preform along the prearranged portion until it is substantially the same as a cross sectional periphery of the preform adjacent the prearranged portion by flowing material of the protrusion into at least the connecting wall.
31. The method according to claim 30, the step of pressing the preform further comprising:
arranging the preform over the punch portion, such that distal second side wall portions opposite the connecting wall contact a contacting surface extending radially from the punch portion; and
guiding a corner portion connecting a first portion of the side wall and the connecting wall and the side wall toward the connecting wall with the die portion.
32. The method according to claim 21, further comprising:
preparing the preform before pressing the preform and increasing the cross sectional thickness of the prearranged portion, the step of preparing the preform comprising:
arranging a plate-shaped material having the cross sectional thickness between the punch portion and the die portion and then mold-clamping to form the preform.
33. The method according to claim 21, further comprising:
increasing a hardness of the prearranged portion of the preform.
34. The method according to claim 21, wherein the preform is an elongated structure with a hat shaped cross section, opposing longitudinal ends and a longitudinally extending protrusion, the method further comprising:
controlling a movement of both longitudinal ends of the preform using a lateral mold during the step of increasing the cross sectional thickness of the prearranged portion.
35. The method according to claim 34, the step of increasing the cross sectional thickness of the prearranged portion further comprising:
restraining a material flow to a portion of the preform surrounding the prearranged portion.
36. The method according to claim 35, wherein the step of restraining is achieved by one of a through hole, a slit, a concave portion or a curved portion arranged adjacent a periphery of the prearranged portion and configured to mitigate transfer of a compression stress.
37. A method of manufacturing a press-molded product using an elongate preform having a plate thickness and comprising a pair of spaced side walls connected by a connecting wall to create a generally hat shaped cross section, the preform having a longitudinal prearranged portion with a protrusion that increases a cross sectional periphery of the preform along the prearranged portion, the method comprising:
pressing the preform within a mold cavity formed between a die portion and a punch portion received within the die portion and a lateral mold, the cavity having a cross sectional thickness when the punch portion is fully received in the die portion that is greater than the plate thickness, the lateral mold controlling a movement of opposing longitudinal ends of the preform; and
compressing the protrusion to flow material of the protrusion into the connecting wall and the side walls, such that the cross sectional periphery of the preform along the prearranged portion is substantially the same as a cross sectional periphery of the preform adjacent the prearranged portion, a cross sectional thickness of the prearranged portion is increased from the plate thickness, a cross sectional thickness of the preform excepting the prearranged portion remains at the plate thickness, and an length of the preform is substantially unchanged.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A superconducting coil unit for a magnet, said coil unit comprising:
(a) a coil;
(b) a thermal shield surrounding the coil;
(c) a vacuum vessel surrounding the coil, said vacuum vessel including a service port wall;
(d) a hollow tubular element having a wall which is at least partially flexible extending in an inward direction into the vessel from said service port wall to said shield, said hollow tubular element defining an interior space;
(d) a cryocooler having a first heat extraction element, said first heat extraction element being disposed within said tubular element when said cryocooler is in an operating position;
(e) a thermal conductor extending through the wall of said tubular element, said thermal conductor including an interior portion disposed in said interior space and a flexible exterior portion disposed outside of said tubular element and connected to said shield, said first heat extraction element of said cryocooler being attached to said interior portion of said thermal conductor for heat transfer therebetween, said flexible tubular element and said flexible exterior portion of said thermal conductor permitting movement of said cryocooler outwardly from said operating position to a retracted position.
2. A coil unit as claimed in claim 1 wherein said first heat extraction element is releasably attached to said interior portion of said thermal conductor.
3. A coil unit as claimed in claim 1 wherein said first heat extraction element is bolted to said interior portion of said thermal conductor.
4. A coil unit as claimed in claim 1 further comprising a cryogen reservoir disposed inside said thermal shield, said tubular element extending to said cryogen reservoir so that said interior space of said tubular element communicates with said cryogen reservoir, said cryocooler having a second heat extraction element disposed inward of said first heat extraction element in proximity to the cryogen reservoir.
5. A coil unit as claimed in claim 4 wherein said interior space within said tubular element communicates with the exterior of said vacuum vessel.
6. A coil unit as claimed in claim 4 wherein said cryocooler is not rigidly connected to said vacuum vessel, said shield or said cryogen reservoir.
7. A coil unit as claimed in claim 5 wherein said tubular element extends substantially vertically downwardly from said service port wall.
8. A coil unit as claimed in claim 6 further comprising a bracket supported above said service port wall, said cryocooler being supported by said bracket.
9. A method of assembling a magnetic resonance imaging magnet comprising the steps of:
(a) providing a ferromagnetic frame defining an axis;
(b) positioning each one of a pair of generally hoop-like coil units each including a coil and each having a central opening by advancing the coil unit in a lateral direction transverse to the axis until the central opening of the coil unit is aligned with the axis and then moving the coil unit axially; and
(c) after said positioning step, assembling at least a portion of at least one pole to the frame so as to form poles extending along said axis, each one of the coil units having an axial dimension larger than a clearance between the poles.
10. A method as claimed in claim 9 wherein, prior to said positioning step, said frame includes a pair of ferromagnetic pole stems projecting towards one another along the axis, said pole stems having ends confronting one another, said assembling step including mounting at least one pole cap to at least one of said pole stems.
11. A method as claimed in claim 9 wherein each said coil unit includes a superconducting coil and a generally toroidal vessel surrounding the coil and defining the central opening of the coil unit, said vessel having support extensions extending parallel to one another and transverse to the plane of the toroidal vessel, said frame includes a pair of walls extending transverse to the axis, and said step of moving each said coil unit axially includes engaging said support extensions within recesses in said walls.
12. A method as claimed in claim 9 further comprising the step of assembling at least one flux return member to said walls before positioning said coil units and assembling at least one other flux return member to said side walls after positioning said coil units.
13. A method of assembling a magnetic resonance imaging magnet comprising the steps of:
(a) positioning a pair of ferromagnetic walls substantially parallel to one another so that inner surfaces of the side walls confront one another; then
(b) positioning each one of a pair of generally hoop-like coil units each including a coil and each having a central opening by advancing the coil unit in a lateral direction parallel to the inner surfaces of the side walls until the central openings of the coil unit are aligned along an axis extending between the side walls; and
(c) after said positioning step, assembling at least one ferromagnetic flux return member with the side walls so that such flux return member extends between the side walls,
wherein each said coil unit includes a superconducting coil and a generally toroidal vessel surrounding the coil and defining the central opening of the coil unit, said vessel having support extensions extending parallel to one another and transverse to the plane of the toroidal vessel, and wherein the step of positioning each coil unit includes moving the coil unit parallel to the axis to engage the support extensions in recesses in the walls.