Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
  • B29C70/32—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core on a rotating mould, former or core
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D23/00—Producing tubular articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/76—Cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2101/00—Use of unspecified macromolecular compounds as moulding material
  • B29K2101/10—Thermosetting resins

Definitions

• This invention relates generally to mandrels for forming hollow parts from a heat curable material.
• Elongate hollow machine parts are increasingly constructed from non-metal materials, such as composite materials.
• composite materials are constructed by a heat curing process.
• mandrels are typically made from steel, and therefore have a much larger coefficient of thermal expansion than the non-metal material.
• This may cause the lateral projection of the non-metal part to prematurely disengage from the support provided by the lateral member. Such premature disengagement frequently leads to porosity, delaminations and/or other laminate quality problems in the non-metal part.
• the invention satisfies this need.
• the invention is a mandrel suitable for forming a hollow part, wherein the part is made from a heat curable material having a first coefficient of expansion, has an elongate body with a longitudinal axis and has a lateral projection attached to the body which extends away from the body, the mandrel comprising (a) an elongate central member having a first end, an opposed second end, a longitudinal axis, an outer surface and a second coefficient of expansion which is different than the first coefficient of expansion, (b) a lateral member disposed at a first location and projecting away from the outer surface of the central member, the lateral member being slidably attached to the central member such that the lateral member is slidable along a path parallel to the longitudinal axis of the central member, and (c) a rigid elongate strut member having a first end, a second end and a coefficient of expansion substantially similar to the first coefficient of expansion, the first end of the
• Figure 1 is a perspective view of a first mandrel having features of the invention
• Figure 2 is a side view of the mandrel illustrated in Figure 1 ;
• Figure 3 is an end view of the mandrel illustrated in Figure 1;
• Figure 4 is a cross-sectional side view of the mandrel illustrated in Figure 3, taken along line 4-4;
• Figure 5 is a perspective view of a second mandrel having features of the invention.
• Figure 6 is a cross-sectional side view of the mandrel illustrated in Figure 5.
• the invention is a mandrel 10 suitable for forming a hollow part, wherein the part is made from a heat curable material having a first coefficient of expansion, an elongate body with a longitudinal axis and has a lateral projection attached to the body which extends away from the body.
• the heat curable material can be a composite of a fiber and a matrix.
• Fiber materials include carbon, graphite, fiberglass, quartz, ceramic, aramid, nanno fiber, UHMWPE, basalt, and other structural reinforced fibers.
• Matrices can include epoxy, polyimide, bismaleimide, pheolic, thermoplastic, polyester, vinyl ester, cyanate ester, ceramics or other polymeric composite matrix. The fiber and the matrix can be in any combination.
• the mandrel 10 comprises an elongate central member 12, one or more movable lateral members 14 and at least one rigid elongate strut member 16.
• the central member 12 is elongate and has a first end 18, an opposed second end 20, a longitudinal axis 22 and an outer surface 24. Typically, the central member 12 is between about four feet and about 20 feet in length, most typically between about three feet and about eight feet in length ⁇ such as about five feet in length.
• the central member 12 is made from steel. However, other alloys can be used, such as aluminum or nickel-steel alloys such as Invar®.
• the central member 12 in many applications can also be made from a carbon reinforced composite or carbon composites.
• the central member 12 has a coefficient of expansion which is markedly different than the first coefficient of expansion. The difference in coefficient of expansion would result in detriment during the curing of the composite. Typically, the coefficient of expansion is "markedly different,” meaning that the coefficient of expansion of the central member differs from the first coefficient of expansion by at least 5%.
• the outer surface 24 of the central member 12 has circular cross-sections throughout the length of the central member 12.
• the outer surface 24 of the central member 12 is a right circular cylinder having equal circular cross-sections throughout the length of the central member 12.
• the circular cross- sections of the outer surface 24 of the central member 12 is larger at the first end 18 than at the second end 20.
• the outer surface 24 of the central member 12 can have many other shapes, including shapes having elliptical cross-sections and polygon cross-sections (such as square cross-sections, rectangular cross-sections, octagonal cross-sections, etc.).
• Central members 12 having irregular cross-sections can also be used in the invention.
• the central member 12 defines an internal passageway 26 having circular cross-sections.
• the central member 12 defines an internal passageway 26 which is a right circular cylinder, having the same circular cross-sections throughout the length of the central member 12.
• the central member 12 defines an internal passageway 26 having circular cross-sections, but the internal passageway 26 at the first end 18 of the central member 12 is larger in diameter than the passageway at the second end 20.
• the lateral member 14 is disposed at a first location 28 and projects away from the outer surface 24 of the central member 12.
• the lateral member 14 is slidably attached to the central member 12, such that the lateral member 14 is slidable along a path parallel to the longitudinal axis 22 of the central member 12 and in the direction of a second location 30 spaced apart from the first location 28.
• the mandrel 10 further comprises a second lateral member 32 disposed at the second location 30 and projecting away from the outer surface 24 of the central member 12.
• the second lateral member 32 is slidably attached to the central member 12 such that the second lateral member 32 is slidable along a path substantially parallel to the longitudinal axis 22 of the central member 12.
• the second lateral member 32 can be rigidly affixed to the central member 12.
• Embodiments with a second lateral member 32 allow the mandrels 10 to form parts having opposed lateral projections, such as a pair of opposed end flanges.
• the elongate strut member 16 is rigid, has a first end 34, a second end 36 and a coefficient of expansion substantially similar to the first coefficient of expansion.
• substantially similar it is meant that the coefficient of expansion of the strut member 16 is close enough to cause sufficient positive contact between the part and the lateral member 14 of the mandrel 10 during curing and cool-down of the part to prevent detriment in the finished part.
• the elongate strut member 16 has a coefficient of expansion within about 5% of the first coefficient of expansion.
• the strut member 16 is made from the same material as the part.
• the coefficient of expansion is identical to the first coefficient of expansion.
• many other materials can be used to form the strut member 16, so long as the strut member 16 has a coefficient of expansion substantially similar to the first coefficient of expansion. Examples of such other materials include composite materials having fibers of carbon, graphite, fiberglass, quartz, ceramic, aramid, nanno fiber, UHMWPE, basalt, and other structural reinforced fibers, and having matrices of epoxy, polyimide, bismaleimide, pheolic, thermoplastic, polyester, vinyl ester, cyanate ester, ceramics or other polymeric composite matrix.
• the first end 34 of the strut member 16 is affixed to the lateral member 14 and the second end 36 of the strut member 16 is affixed at the second location 30.
• the strut member 16 is disposed substantially parallel to the longitudinal axis 22 of the central member 12.
• the elongate strut member 16 comprises a plurality of rigid elongate strut members 16.
• the mandrel 10 comprises three elongate strut members 16.
• the mandrel 10 comprises six elongate strut members 16.
• the strut members 16 are affixed at the second location 30 to the slidable second lateral member 14.
• the strut members 16 can be affixed to a non-slidable second lateral member disposed at the second location 30. In still other embodiments, the strut member 16 can be attached at the second location 30 to a plate or wall not part of the mandrel 10 but rigidly disposed with respect to the central member 12.
• the elongate strut member 16 is typically a solid cylindrical member, the embodiments illustrated in the drawings, the elongate strut members 16 are right circular cylinders having cross-sectional diameters, typically between about 0.1 inch and about 4 inches.
• the invention is also a method of using the mandrel 10 described above.
• the mandrel 10 is used to form a hollow part made from a heat curable material having a first coefficient of expansion, wherein the part comprises (i) an elongate body with a first end, a second end and a longitudinal axis, and (ii) a lateral projection attached to the body which extends away from the body, the method comprising the steps of (a) providing the mandrel 10 of the invention, (b) forming the body of the part by applying heat curable material to the outer surface 24 of the central member 12 of the mandrel 10, (c) forming a lateral projection by applying the heat curable material to an inner surface 38 of the lateral member 14, (d) tightly retaining the body of the part and the lateral projection of the part to the mandrel 10 while heating the curable material to an elevated temperature while maintaining contact between the lateral projection and the inner surface of the lateral member 14, and (e) after the part has cured, cooling the
• the invention solves the problems discussed in the Background Section, above. Because the lateral member 14 is allowed to slide along the central member 12, and because the elongate strut member 16 has a coefficient of expansion substantially similar to the coefficient of expansion of the part being formed with the mandrel 10, in the heating and cooling of the mandrel 10 and the part does not cause a premature disengagement of the part from the lateral member 14 of the mandrel 10. Also, because the lateral member 14 is allowed to slide along the central member 12, there is no danger of the lateral member crushing the lateral projection during cool-down.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Moulding By Coating Moulds (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Rod-Shaped Construction Members (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 2011
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