US20070013105A1 - Post-Forming of Thermoplastic Ducts - Google Patents

Abstract

An apparatus and method are provided for thermoplastically forming a contour in a thermoplastic duct defining a passage. The apparatus includes a longitudinal collar that defines a cavity and a rigid inner support structure extending longitudinally in the cavity. The collar and/or the inner support structure define a mold contour. One or more heaters are configured to heat at least a formation portion of the duct to a formation temperature. An expansion member, such as an expandable elastomer, which is disposed between an inner surface of the collar and an outer surface of the inner support structure, is configured to urge the formation portion of the duct against the mold contour to thermoplastically form the duct.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application is a divisional of U.S. application Ser. No. 10/215,780, filed Aug. 9, 2002, which is hereby incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
• 1) Field of the Invention
• The present invention relates to apparatuses and methods for forming thermoplastic materials and, more specifically, for post-forming features in thermoplastic ducts.
• 2) Description of Related Art
• Ducts provide transport passageways for a wide variety of applications. For example, tubular ducts are widely used for air flow in aircraft environmental control systems. Similarly, ducts provide passageways for transporting gases for heating and ventilation in other vehicles and in buildings. Water distribution systems, hydraulic systems, and other fluid networks also often use ducts for fluid transport. In addition, solid materials, for example, in particulate form can be delivered through ducts. Ducts for the foregoing and other applications can be formed of metals, plastics, ceramics, composites, and other materials.
• One conventional aircraft environmental control system utilizes a network of ducts to provide air for heating, cooling, ventilation, filtering, humidity control, and/or pressure control of the cabin. In this conventional system, the ducts are formed of a composite material that includes a thermoset matrix that impregnates, and is reinforced by, a reinforcing material such as Kevlar®, registered trademark of E.I. du Pont de Nemours and Company. The thermoset matrix is typically formed of an epoxy or polyester resin, which hardens when it is subjected to heat and pressure. Ducts formed of this composite material are generally strong and lightweight, as required in many aircraft applications. However, the manufacturing process can be complicated, lengthy, and expensive, especially for ducts that include contours or features such as beads and bells. For example, in one conventional manufacturing process, ducts are formed by forming a disposable plaster mandrel, laying plies of fabric preimpregnated with the thermoset material on the mandrel, and consolidating and curing the plies to form the duct. The tools used to mold the plaster mandrel are specially sized and shaped for creating a duct of specific dimensions, so numerous such tools must be produced and maintained for manufacturing different ducts. The plaster mandrel is formed and destroyed during the manufacture of one duct, requiring time for curing and resulting in plaster that typically must be removed or destroyed as waste. Additionally, the preimpregnated plies change shape during curing and consolidation and, therefore, typically must be trimmed after curing to achieve the desired dimensions. The jigs required for trimming and for locating the proper positions for features such as holes and spuds are also typically used for only a duct of particular dimensions, so numerous jigs are required if different ducts are to be formed. Like the rotatable tools used for forming the mandrels, the jigs require time and expense for manufacture, storage, and maintenance. Additionally, ducts formed of conventional thermoset epoxies typically do not perform well in certain flammability, smoke, and toxicity tests, and the use of such materials can be unacceptable if performance requirements are strict.
• Features such as beads typically must be post-formed, or added after the formation of the duct, by disposing a fiberglass rope and/or additional plies on the outer surface of the duct and curing the rope and/or plies. This additional step requires additional manufacture time and labor, adding to the expense of the duct, and the additional materials add to the weight of the duct. As an alternative to post-forming, features can also be formed by providing a corresponding contour on the disposable mandrel, for example, by using a tapered mandrel to form a bell shape in the duct. However, this further complicates the process of preparing the mandrel. Also, the shape or size of the plies can change during curing, resulting in unpredictable changes to the placement of the feature.
• Thus, there exists a need for an improved apparatus and method of forming features such as beads and bells in ducts. The method should not require the laying of individual plies on a disposable plaster mandrel. Preferably, the method should be compatible with thermoplastic ducts, including reinforced thermoplastic ducts formed from flat sheets, which provide high strength-to-weight ratios and meet strict flammability, smoke, and toxicity standards. Further, the method should preferably not require the addition of added materials for forming the features.
SUMMARY OF THE INVENTION
• The present invention provides an apparatus and method for thermoplastically forming contours in ducts. The ducts can be formed of a thermoplastic material, such as flat sheets of reinforced thermoplastic laminate, and the contour can be formed by post-forming the duct. Thus, individual plies need not be laid on a disposable plaster mandrel, and additional materials do not need to be added to the duct for forming the features. Additionally, the thermoplastic material can be lightweight, strong, and perform well in flammability, smoke, and toxicity tests. Further, the method is compatible with ducts that are formed by consolidation joining thermoplastic laminates.
• According to one embodiment, the present invention provides an apparatus for thermoplastically forming a contour in a thermoplastic duct defining a passage. The apparatus includes a longitudinally extending collar with an inner surface that defines a cavity. An inner support structure, which can be rigid, extends longitudinally in the cavity and has an outer surface that opposes the inner surface of the collar. The collar and/or the inner support structure define a mold contour. An expansion member, which can be formed of an elastomeric material, is disposed between the inner and outer surfaces and partially or continuously around the inner support structure, such that the expansion member can urge a formation portion of the duct against the mold contour and thereby thermoplastically form the duct. Additionally, a heater can be configured to heat the formation portion of the duct to a formation temperature, and an alignment device can be configured to support the duct along a longitudinal axis collinear with that of the collar.
• According to one aspect of the invention, the expansion member is configured to expand radially and urge the formation portion of the duct radially outward against the mold contour, which is defined by the inner surface of the collar. The mold contour can define a bead shape characterized by a continuous slot extending around the outer support. The inner support structure can define a channel for receiving the expansion member, and the channel can be adjustable in the longitudinal direction to compress the expansion member and urge the expansion member radially toward the mold contour. For example, the inner support structure can include a first portion with a face defining an aperture for receiving a second portion longitudinally, the face and the second portion defining the channel so that insertion of the second portion adjusts the width of the channel. An actuator can be provided for adjusting the portion(s) of the inner support structure to expand the expansion member. The expansion member can also be an inflatable bladder that is configured to receive a fluid for inflating so that the bladder expands radially outward from the channel and urges the formation portion of the duct toward the mold contour. According to another aspect, the expansion member is configured to urge the formation portion of the duct radially inward against the mold contour, which is defined by the outer surface of the inner support. For example, the inner support can define a tapered bell contour.
• The expansion member can be formed of elastomeric material that expands when heated. A plurality of heaters can extend at least partially through the inner support structure, and one or more heaters can be positioned radially outside said cavity and configured to radiate heat radially inward to the duct. An insulative material can also be included proximate to the collar to retain heat in the cavity.
• According to another aspect of the invention, the apparatus includes a rigid inner support structure that is configured to extend longitudinally in the passage of the duct and has an outer surface configured to correspond to a desired configuration of the duct. A heater assembly, such as a heater positioned within the inner support structure, is configured to heat a formation portion of the duct to at least a formation temperature. A heat shrinkable tape is configured to be disposed circumferentially on the formation portion of the duct. The outer surface of the inner support structure defines a mold contour and the heat shrinkable material is adapted to contract radially when heated and urge the formation portion of the duct radially inward against the mold contour to thermoplastically form the duct. Further, a consolidation joining head can be configured to adjust radially against an interface portion defined by longitudinal edges of the duct. The head urges the interface portion against the inner support, heats the interface portion to at least a glass transition temperature, and thereby consolidation joins the interface portion.
• The present invention also provides a method of thermoplastically forming a contour in a thermoplastic duct. According to one embodiment, the method includes providing a thermoplastic duct between a collar and an inner support structure, for example, a cured thermoplastic duct formed of a reinforced thermoplastic composite material. A formation portion of the duct is heated to a formation temperature such as a glass transition temperature, and an expansion member is urged against the duct to thermoplastically form the formation portion of the duct radially against a mold contour defined by the collar and/or the inner support structure. Portion(s) of the collar can be separably adjusted to remove the duct therefrom.
• The expansion member can be expanded radially outward or inward against the formation portion of the duct to urge the formation portion against the collar or inner support structure. According to one aspect of the invention, a longitudinal width of a channel can be adjusted to compress the expansion member in the longitudinal direction and expand the expansion member radially outward. For example, fluid can be delivered to an inflatable bladder to inflate the bladder and expand the bladder radially outward against the formation portion of the duct.
• The duct can be heated by electrically energizing at least one resistive heater to generate heat and conducting the heat to the formation portion of the duct. The heat can also expand the expansion member radially to form the formation portion of the duct. Additionally, after heating the duct, and at least partially concurrent with the urging of the duct, the joint can be cooled to a temperature less than a glass transition temperature.
• According to another aspect of the invention, a rigid inner support structure is configured to extend longitudinally in a passage of the duct such that a mold contour defined by an outer surface of the inner support structure and corresponding to a desired configuration of the duct is located proximate to a formation portion of the duct. Heat shrinkable tape is disposed circumferentially around the formation portion of the duct. The tape and at least a formation portion of the duct are heated to at least a formation temperature, such that the tape contracts radially inward urging the formation portion of the duct radially against the mold contour and thermoplastically forms the duct. Further, a consolidation joining head can be adjusted radially inward against an interface portion of the duct defined by longitudinal edges of the duct. The interface portion is thereby urged against the inner support and heated to at least a glass transition temperature, thus, consolidation joining the interface portion.
BRIEF DESCRIPTION OF THE DRAWINGS
• Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
• FIG. 1 is a perspective view of a forming apparatus according to one embodiment of the present invention;
• FIG. 2 is a perspective view of a thermoplastic duct with a bead formed according to one embodiment of the present invention;
• FIG. 3 is a perspective view of a thermoplastic duct with a bell formed according to one embodiment of the present invention;
• FIG. 4 is a perspective view of the mold collar and heater of the forming apparatus ofFIG. 1;
• FIG. 5 is plan view of the first portion of the mold collar ofFIG. 4;
• FIG. 6 is an exploded perspective view of the holder of the forming apparatus ofFIG. 1;
• FIG. 7 is an exploded perspective view of the alignment supports of the forming apparatus ofFIG. 1;
• FIG. 8 is a perspective view of the first portion of the inner support structure of the forming apparatus ofFIG. 1;
• FIG. 9 is a perspective view of the second portion of the inner support structure of the forming apparatus ofFIG. 1;
• FIG. 10 is a section view of the forming apparatus ofFIG. 1;
• FIG. 11 is a section view of the forming apparatus ofFIG. 1 with the second portion of the inner support structure inserted into the first portion from its position inFIG. 10;
• FIG. 12 is an elevation view of an inner support structure according to one embodiment of the present invention;
• FIG. 13 is a partially cut-away side view of the right side of the inner support structure ofFIG. 12;
• FIG. 14 is a perspective view of a forming apparatus according to one embodiment of the present invention;
• FIG. 15 is a section view of a forming apparatus according to one embodiment of the present invention;
• FIG. 15A is a perspective view of the duct with an unjoined portion for forming according to one embodiment of the invention;
• FIG. 16 is a perspective view of a forming apparatus according to another embodiment of the present invention;
• FIG. 17 is a perspective view of the inner mandrel of the forming apparatus ofFIG. 16;
• FIG. 18 is a perspective view of the inner mandrel, duct, and elastomeric layer of the forming apparatus ofFIG. 16;
• FIG. 19 is an exploded view of the outer mandrel of the forming apparatus ofFIG. 16;
• FIG. 20 is a perspective view of a forming apparatus according to another embodiment of the present invention; and
• FIG. 21 is a perspective view of a forming apparatus according to another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
• The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
• Referring now toFIG. 1, there is shown a formingapparatus10 for forming features in a thermoplastic member, such as aduct12 with apassage13, according to one embodiment of the present invention. For example, the formingapparatus10 can be used to formbeads14 and/orbells15 inducts12 as shown inFIGS. 2 and 3 respectively. Preferably, theduct12 is formed of a composite laminate that includes a thermoplastic matrix and a reinforcing material. Thermoplastic materials are characterized by a transition to a plastic state when heated above a glass transition temperature. For example, theduct12 can be formed of polyetherimide (PEI) or polyphenol sulfide (PPS), both of which can be thermoplastic. Thermoplastic PEI is available under the trade name Ultem®, a registered trademark of General Electric Company. According to one embodiment of the present invention, theduct12 is formed of a composite material that includes a matrix of thermoplastic PEI that is reinforced with a fabric or fibers that are formed from a reinforcing material such as carbon, glass, or an aramid such as Kevlar®. Alternatively, theduct12 can be formed of other thermoplastic materials, which can be reinforced by other reinforcing materials, or can include no reinforcing materials. Theduct12 can be used in numerous applications including, but not limited to, environmental control systems of aerospace vehicles, in which air is delivered through thepassage13 of theduct12 to provide heating, cooling, ventilation, and/or pressurization of an aircraft cabin. Theduct12 can be connected to other ducts or other devices such as ventilators, compressors, filters, and the like. Thebeads14 andbells15 can be used to secure theduct12 to other ducts and devices. For example, thebead14 can correspond to an interior contour of a coupling device such as a clamp that is used to join twoducts12. Similarly, thebell15 can receive an end of anotherduct12, and the twoducts12 can be held together by friction, glue, fasteners, consolidation joining, or other methods. Additionally,multiple ducts12 can be connected so that a longitudinal axis of eachduct12 is configured at an angle relative to the longitudinal axis of the adjoining duct(s)12. Thus, theducts12 can be connected to form an intricate duct system (not shown) that includes numerous angled orcurved ducts12 for accommodating the devices connected by the duct system and for meeting layout restrictions as required, for example, on an aircraft where space is limited.
• The formingapparatus10 includes amold collar20, which is shown inFIGS. 4 and 5. Themold collar20 extends longitudinally from afirst end22 to asecond end24 and defines aninner surface26 directed toward acavity28. Preferably, thecavity28 has a circular cross section and corresponds to the outer diameter of theduct12, but thecavity28 can also be non-circular, for example, for formingducts12 that have rectangular, triangular, or elliptical cross-section shapes. In this embodiment, thecavity28 extends through thecollar20 from thefirst end22 to thesecond end24, but in other embodiments thecavity28 can extend partially therethrough. Themold collar20 can include a single monolithic member or multiple members, such as first and secondseparable portions30,32. Theportions30,32 defineholes36 for receiving bolts (not shown) that connect theportions30,32, though other fasteners or clamps can similarly be used. Preferably, themold collar20 is formed of a thermally conductive material, such as aluminum, steel, titanium, and alloys thereof, and theportions30,32 can be assembled tightly around theduct12 such that theinner surface26 of themold collar20 contacts theduct12 and heat can be conducted through themold collar20 to theduct12 during processing. Theinner surface26 of themold collar20 defines amold contour34, i.e., a contour that corresponds to a desired feature of theduct12. Preferably, themold collar20 defines acontinuous mold contour34 that extends circumferentially around theinner surface26. For example, themold contour34 of thefirst portion30 shown inFIG. 5 is a bead shape that corresponds to the desiredbead14 ofFIG. 2. With the first andsecond portions30,32 assembled as shown inFIG. 4, the bead shapedmold contour34 ofFIG. 5 is a continuous slot defined by bothportions30,32 of themold collar20 that extends around a longitudinal axis of themold collar20. Alternatively, themold contour34 can comprise multiple non-continuous sections and can extend longitudinally.
• As shown inFIG. 4, anouter heater50 can be positioned around themold collar20. For illustrative clarity, theouter heater50 andmold collar20 are shown assembled without theduct12 inFIG. 4. Preferably, theouter heater50 is configured to be positioned and secured upon themold collar20 such that theouter heater50 is proximate to and aligned with themold contour34. Theouter heater50 can be any of a number of different kinds of heaters and can include a single heating device or multiple heating devices, such electrical resistive heaters. Theouter heater50 can include two separable segments, as shown inFIG. 4, that are secured around themold collar20 by bolts or another fastening or clamping mechanism. For example, theouter heater50 can be an adjustable clamp heater such as a mica band heater available from Heatron, Inc., Leavenworth, Kans. Alternatively, theouter heater50 can be an integral part of themold collar20.
• Aninsulative holder60, shown inFIG. 6, defines anaperture68, which is used to support theduct12 with themold collar20 andouter heater50. Theholder60 can be formed of a phenolic material, i.e., a material formed of a thermoset resin, or other heat resistant materials. Preferably, theholder60 insulates themold collar20 to minimize heat loss from theduct12 during heating. As illustrated inFIG. 6, theholder60 can comprise first andsecond members62,64 that can be separated to facilitate the insertion and removal of theduct12,mold collar20, andouter heater50. Bolt holes66 can receive bolts (not shown) for securing themembers62,64. Theholder60 can also define aninner contour70 within theaperture68 that corresponds to theduct12,mold collar20, and/orouter heater50. For example, theinner contour70 can define channels, pockets, or other contours that receive at least one of theduct12,mold collar20, andouter heater50. Thus, theaperture68 and theinner contour70 can be configured such that theholder60 retains theduct12,mold collar20, andouter heater50 therein.
• Similarly, theholder60 can be configured to retain one or more longitudinal alignment supports80, shown individually inFIG. 7. Eachsupport80 comprises a partial hollow cylinder or another shape that correspond to the outside of theduct12. Eachsupport80 also includes arib82 or other mechanism for engaging or connecting to theholder60. Theribs82 correspond with theinner contour70 of theholder60 such that the alignment supports80 can be configured to align theduct12, longitudinally in this embodiment, with themold collar20. Alternatively, the alignment supports80 can be connected directly to themold collar20. The supports80 can be formed of a variety of materials including, for example, aluminum, steel, ceramics, polymers, and the like.
• The formingapparatus10 also includes aninner support structure90, which can be formed of various materials such as aluminum, steel, titanium, and alloys thereof. Preferably, at least part of theinner support structure90 is formed of a thermally conductive material so that heat can be conducted radially outward to theduct12 as described below. In one embodiment, theinner support structure90 includes first andsecond portions94,96 which are separable, as shown inFIGS. 8 and 9, respectively. Thefirst portion94 defines anouter surface92 that corresponds to the inside of theduct12. A bore98 extends through theinner support structure90 in order to provide a material savings and to correspondingly reduce the weight, but the bore can also extend only partially through thesupport structure90 or be omitted from thesupport structure90. Thefirst portion94 has aface100 that defines anaperture102 for receiving thesecond portion96. Thesecond portion96 also defines aface104 that, when directed towardface100 of thefirst portion94, can be received by thefirst portion94. Alip106 limits the extent to which thesecond portion96 can be inserted intoaperture102 of thefirst portion94. Thesecond portion96 also includes one ormore studs108, six shown inFIG. 9, which extend throughcorresponding holes110 of thefirst portion94 when thesecond portion96 is inserted into thefirst portion94. Nuts (not shown) can be threaded onto thestuds108 such that the nuts retain thestuds108 in theholes110 and retain thesecond portion96 in theaperture102 of thefirst portion94. Thestuds108 also serve to align the first andsecond portions94,96.
• Anexpansion member130 is disposed on thesecond portion96 proximate to thelip106. When the nuts are tightened on thestuds108, as illustrated byFIGS. 10 and 11, thesecond portion96 is pulled further into theaperture102 of thefirst portion94 until theexpansion member130 contacts theface100 of thefirst portion94. Further tightening of the nuts compresses theexpansion member130 in the longitudinal direction between theface100 and thelip106. Preferably, theexpansion member130 is formed of an elastomeric material such as rubber, silicon, neoprene, or latex that is elastically deformable. For example, theexpansion member130 can be formed of a moldmaking silicone, such as Shin-Etsu 1300T. Thus, by tightening the nuts, theexpansion member130 can be expanded radially outward from thesecond member96 to urge theduct12 against themold collar20.
• According to one method of operation, theinner support structure90 is positioned in thepassage13 of theduct12 as shown inFIG. 1 such that theouter surface92 of thefirst portion94 is positioned within and contacts thepassage13 of theduct12. Theinner support structure90 can include a bore (not shown) to receive analignment guide38, which extends from thefirst end22 of themold collar20, so that theinner support structure90 can be positioned in a predetermined angular position in theduct12. At least oneheater120 is provided within thepassage13 of theduct12 to heat theduct12 during forming. For example, as shown inFIG. 10, rod, or cartridge,heaters120 are disposed in thefirst portion94 of theinner support structure90 and extend from theface100 into theaperture102. Onesuch heater120 is a 500 watt cartridge heater manufactured by Watlow Electric Manufacturing Company, St. Louis, Mo. Correspondingholes122 in thesecond portion96 of theinner support structure90 are structured to receive therod heaters120. Preferably, therod heaters120 extend to a position proximate to theexpansion member130, and theexpansion member130 is positioned at a longitudinal position in thepassage13 of theduct12 that corresponds to the longitudinal position of themold contour34 of themold collar20, for example, as shown inFIGS. 10 and 11. Thus, aformation portion16 of theduct12, i.e., theportion16 of theduct12 that is to be thermoplastically formed to make the bead, is disposed between theexpansion member130 and themold contour34 of themold collar20, and therod heaters120 are positioned proximate to and generally aligned with theformation portion16 of theduct12.
• Therod heaters120 can be connected to apower supply124, and theouter heater50 can be connected to thepower supply124 or a different source of power. Theheaters50,120 are preferably energized such that theformation portion16 of theduct12 is heated to a formation temperature, such as a temperature higher than the glass transition temperature of thethermoplastic duct12. For example, in one embodiment, theduct12 is formed of a composite thermoplastic material comprising PEI reinforced with Kevlar® aramid and has a glass transition temperature of about 417° F. The duct can be formed at temperature less than the glass transition temperature, for example, about 350° F., but preferably is formed at higher temperatures to minimize stress on the reinforcing Kevlar® aramid. For example, in one advantageous embodiment, theduct12 is formed at a temperature of between about 460° F. and 480° F., for a hold or processing time of between about 20 and 45 minutes.
• Before or concurrently with the heating of theformation portion16 of theduct12, theexpansion member130 is expanded radially to urge theformation portion16 of theduct12 against themold contour34. For example, a tightening adjustment of thenuts109, illustrated byFIG. 11 relative toFIG. 10, results in the radially outward expansion of theexpansion member130. As shown, the tightening of thenuts109 advances thesecond portion96 of theinner support structure90 into theaperture102 of thefirst portion94, thereby compressingexpansion member130 longitudinally and expanding theexpansion member130 radially against theduct12. While theduct12 is at the formation temperature, theexpansion member130 urges theformation portion16 against themold contour34 and thermoplastically forms theformation portion16 to the desired shape of theduct12, which defines a bead in this embodiment. After processing at the formation temperature, theduct12 can be at least partially cooled in the formingapparatus10, for example, to a temperature less than the glass transition temperature.
• In another embodiment of the present invention, illustrated inFIGS. 12 and 13, aninner support structure140 comprises a single structure that defines achannel142. Disposed in thechannel142 is an expansion member, which is an elastomericinflatable bladder144 defining at least oneinternal chamber146. Theinflatable bladder144 is configured to receive a fluid, such as air, into theinternal chamber146 and thereby be expanded radially outwards. Thus, theinner support structure140 can be positioned within thepassage13 of theduct12, and theduct12 can be positioned in themold collar20,outer heater50, andholder60 as described above in connection withFIG. 1. A fluid source (not shown) can be fluidly connected to theinflatable bladder144, for example, via thefluid line146, andheaters148, similar to theheaters120 described above, can be connected to a power supply (not shown), for example, viawires152. Theheaters148 can be used to heat theduct12, and theinflatable bladder144 can be used to urge theformation portion16 of theduct12 against themold contour34 and thereby thermoplastically form theformation portion16 to the desired shape of theduct12.
• Although the formingapparatus10 is illustrated in the foregoing figures as a bead forming apparatus, theapparatus10 can also be used to form other features by changing the configuration of themold contour34. For example, the shape of themold contour34 can define other continuous shapes extending arcuately around theinner surface26 of themold collar20, one or more non-continuous shapes, longitudinally extending shapes, and the like. Additionally, it is understood that the placement of theduct12 in the formingapparatus10 determines the position and, in part, the shape of the resulting feature. Therefore, theduct12 can be inserted into the formingapparatus10 according to the desired placement of the feature. For example, as shown inFIG. 10, thefirst portion94 of theinner support structure90 is wider than theduct12, and theduct12 does not extend through thefirst portion94 but rather is inserted to abut thefirst portion94. Theduct12 can also be inserted to a lesser extent, i.e., so that theduct12 does not abut thefirst portion94. Alternatively, thefirst portion94 of theinner support90 can fit within thepassage13 of theduct12 so that theduct12 can extend, for example, to thefirst end22 of themold collar20, or even beyond themold collar20. Thus, theinner support structure90,mold collar20, or an additional component of the formingapparatus10 can function as a placement reference for theduct12 so that theformation portion16 of theduct12 is positioned proximate to themold contour34 and the feature is imparted onto theduct12 at the desired location. Further, the positioning of theduct12 in the formingapparatus10 can affect the shape of the feature if theduct12 is inserted such that theformation portion16 occurs at the end of theduct12 and only part of the feature is imparted onto theduct12. For example, themold contour34 shown inFIG. 5, which typically forms thebead14 on theduct12, can also be used to form a short, outwardly flared, or bell shaped, feature by inserting theduct12 so that theduct12 extends only partially through themold contour34 and theformation portion16 occurs at the end of theduct12.
• A bell feature can also be formed according to the present invention using a formingapparatus150 such as the one shown inFIG. 14. The formingapparatus150 includes abase structure152 that supports amandrel160 and aclamping mechanism170. Themandrel160 is configured within theclamping mechanism170 such that theduct12 can be inserted therebetween. As shown inFIG. 15, themandrel160 defines anouter surface162 that tapers from a first diameter d₁to a second, smaller diameter d₂. Preferably, theduct12 corresponds to the second diameter d₂and at least a portion of the duct can be configured to correspond to the larger first diameter d₁. For example, as shown inFIG. 15A, theduct12 can include aninterface portion17 defined by unjoined and overlappinglongitudinal edges18,19 of theduct12, e.g., a portion of theedges18,19 that were left unjoined in a prior joining process as discussed in U.S. application Ser. No. ______, titled “Consolidation Joining of Thermoplastic Laminate Ducts,” filed concurrently herewith, the entirety of which is incorporated by reference. The unjoined edges18,19 allow theduct12 to be inserted onto themandrel160 and configured, at least partially, to the first diameter d₁.
• The mandrel includes aheater164 disposed in the wall of themandrel160, though in other embodiments, theheater164 can instead be positioned within acentral bore166 of themandrel160 or otherwise located in theapparatus150. Theclamping mechanism170 at least partially surrounds themandrel160, and theduct12 can be inserted axially into theapparatus150, e.g., from the right inFIG. 15, so that thepassage13 of theduct12 receives themandrel160, and theduct12 is retained tightly between theclamping mechanism170 and themandrel160. Thebase structure152, theclamping mechanism170, and themandrel160 can be formed of any material with sufficient strength for supporting theduct12 during processing, for example, aluminum, steel, titanium, and alloys thereof.
• Preferably, theinner surface174 of theclamping mechanism170 is defined by anelastomeric layer176 such that theelastomeric layer176 can be urged radially toward theduct12 and retained between theclamping mechanism170 and themandrel160. Theheater164 is configured to heat theduct12 to a formation temperature, e.g., the glass transition temperature, and theelastomeric layer176 preferably can be expanded to urge theduct12 againstouter surface174 of the mandrel. For example, theelastomeric layer176 can comprise a heat expandable material that is axially restrained byend plates178. With theduct12 positioned in the formingapparatus150, theheater164 can be used to heat theformation portion16 of theduct12 to a formation temperature and heat the heat expandableelastomeric layer176. Theelastomeric layer176 expands radially and forces theduct12 against themandrel160. Thus, theduct12 is thermoplastically formed to the shape of theouter surface162 of themandrel160, for example, thebell15. In other embodiments, theelastomeric layer176 can instead comprise an inflatable member similar to theinflatable bladder144 described above. Theelastomeric layer176 can also comprise a solid elastomer, and the formingapparatus150 can include a mechanism for compressing the elastomer, for example, in the axial direction, to thereby expand the elastomer radially inwards. Additionally, theinterface portion17 of theduct12 can be heated to at least the glass transition temperature and thelongitudinal edges18,19 can be consolidation joined by the compressive force exerted thereon by theelastomeric layer176 as described in U.S. application Ser. No. ______, titled “Consolidation Joining of Thermoplastic Laminate Ducts.”
• According to another embodiment of the present invention, analternative forming apparatus200, illustrated inFIGS. 16-19, can be used to at least partially encapsulate theduct12, heat theduct12 to a forming temperature, and form theduct12 against aninner mandrel204. As shown inFIG. 17, theinner mandrel204 has anouter surface206 that corresponds to the desired shape of theduct12. In the illustrated embodiment, theouter surface206 defines a bell shape, though other mold contours and shapes can similarly be provided including beads, ribs, channels, and the like.Bores208 in theinner mandrel204 are configured to receive rod orcartridge heaters210, which are connected to apower supply212, and generate resistive heat. Theinner mandrel204 is inserted into theduct12 as shown inFIG. 18, and anelastomeric layer214 is disposed over theduct12. Theelastomeric layer214 preferably is formed of a heat resistant material that elastically expands when heated, and can be preformed to a hollow cylindrical shape as shown. Anouter mandrel216, which can comprise separable sections as shown inFIG. 19, is then configured to surround theelastomeric layer214. Theouter mandrel216 is secured in abase support structure218, as shown inFIG. 16, which includesend plates220, that are secured bybolts222 or other fasteners. Preferably, theinner mandrel204 is formed of a thermally conductive material, such as aluminum, steel, titanium, or alloys thereof, to conduct heat radially outward from theheaters210 to theduct12. Theouter mandrel216 andbase support structure218 are preferably sufficiently rigid to support theduct12 during processing, and theelastomeric layer214 and/or theouter mandrel216 can be thermally insulative to reduce heat loss from the formingapparatus200.
• During operation, theheaters210 are connected to thepower supply212 and heat the duct to the formation temperature. Theelastomeric layer214 expands radially between theouter mandrel216 and theduct12, and preferably provides sufficient expansive force at the formation temperature to urge theduct12 against theouter surface206 of theinner mandrel204. Additionally, theinterface portion17 of theduct12 can be heated above the glass transition temperature, and theelastomeric layer214 can consolidation join theedges18,19 as discussed above in connection withFIG. 15. After a holding period at the formation temperature, theduct12 can be at least partially cooled in the formingapparatus200, for example, to a temperature less than the glass transition temperature.
• Theclamping mechanism170 and theouter mandrel216 of theapparatuses150,200, respectively, can comprise a variety of devices that resist the radial force of theelastomeric layers176,214. For example, tape (not shown) can be disposed on the exterior of either of theelastomeric layers176,214 before theelastomeric layer176,214 is heated. Preferably, the tape is sufficiently inelastic so that the tape resists the outwardly radial expansion of theelastomeric layer176,214 forcing theelastomeric layer176,214 to expand radially inward against theduct12.
• Alternatively, heat shrinkabletape230 can be used to configure theduct12 to the desired configuration. As shown inFIG. 20, a forming apparatus200acan be configured by positioning a rigidinner support structure204a, similar to theinner mandrel204, longitudinally in thepassage13 of theduct12 so that anouter surface206aof thesupport structure204 corresponds to theformation portion16 of theduct12. For example, theouter support surface206acan define a bell section, as shown inFIG. 20, a bead, or the like. The heat shrinkabletape230 is disposed circumferentially around theformation portion16 of theduct12, and thetape230 can be disposed in one or more layers on theduct12. In operation, thetape230 and theduct12 can be heated byheaters210a, which are connected to apower supply212a. Preferably, thetape230 is configured to shrink when heated to the formation temperature of theduct12 so that thetape230 contracts in length and urges theformation portion16 of theduct12 radially inward against thesupport structure204a. Further, as shown inFIG. 20, the forming apparatus200acan include aconsolidation joining head232, which extends longitudinally and is adapted to be adjusted radially inward against theinterface portion17 of theduct12, i.e., in a direction indicated byreference numeral240. Thehead232 is preferably configured to urge theinterface portion17 against thesupport structure204aand heat theinterface portion17 to at least a glass transition temperature of theduct12, thereby consolidation joining theedges18,19 at theinterface portion17, as provided in U.S. application Ser. No. ______, titled “Consolidation Joining of Thermoplastic Laminate Ducts.” Thehead232 can comprise numerous types of heaters, for example, a flexible heater disposed on an elastomeric block, as discussed in U.S. application Ser. No. ______, titled “Preforming Thermoplastic Ducts,” filed concurrently herewith, the entirety of which is incorporated by reference.”
• While the above formingapparatuses10,150,200,200aare generally described as manually operated devices, eachapparatus10,150,200,200acan also be automated or partially automated. For example,FIG. 21 illustrates a formingapparatus10asimilar to the formingapparatus10 above. The formingapparatus10aincludes at least onehydraulic actuator40 for actuating diehalves30a,30b. Like themold collar20 described previously, the die halves30a,30bdefine amold contour34a, which corresponds to a desired configuration of theduct12. The die halves30a,30balso support a plurality ofheaters120a, which are connected to apower supply124aand heat theduct12 during processing. Thefirst actuator40 is configured to adjust at least one of the die halves30a,30bto an open position relative to aninner support structure90aso that aduct12 can be inserted into the formingapparatus10aand to a closed position so that theduct12 can be retained between the die halves30a,30band theinner support structure90a. A second actuator (not shown) is configured to adjust afirst portion94aand/or a second portion (not shown) of theinner support structure90ato thereby expand anexpansion member130a, as described above in connection withFIGS. 10 and 11. Similarly, actuators can be used to control other functions of the formingapparatuses10,150,200.
• Theduct12 can be formed from a preform (not shown) comprising a flat sheet of thermoplastic laminate, which defines connection features for connecting spuds, brackets, and the like to theduct12. The preform can define a geometric pattern that corresponds to a desired shape or configuration of theduct12, and the geometric pattern can be determined by projecting the desired shape of theduct12 onto a flat laminate sheet. Methods and apparatuses for forming preforms and for determining geometric patterns that correspond to ducts are provided in U.S. application Ser. No. ______, titled “Thermoplastic Laminate Duct,” filed concurrently herewith, the entirety of which is incorporated herein by reference. It is also appreciated that marks can be provided on the preform, for example, to accurately identify the location of post-formed features such as bead and bells or to facilitate the manufacture or assembly of the ducts, as also provided in U.S. application Ser. No. ______, titled “Thermoplastic Laminate Duct.”
• The preform can be bent, or preformed, to the desired shape of the duct and longitudinal ends of the preform can be joined to form the duct. Methods and apparatuses for configuring preforms to the bent, or preformed, configuration are provided in U.S. application Ser. No. ______, titled “Preforming Thermoplastic Ducts.” Methods and apparatuses for consolidation joining preforms to form ducts are provided in U.S. application Ser. No. ______, titled “Consolidation Joining of Thermoplastic Laminate Ducts.”
• Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (18)

1. A method of thermoplastically forming a contour in a thermoplastic duct, the method comprising:

providing a thermoplastic duct between a collar and an inner support structure;

heating at least a formation portion of the duct to at least a formation temperature; and

urging an expansion member against the duct to thermoplastically form the formation portion of the duct radially against a mold contour defined by one of the collar and inner support structure.

2. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, wherein said providing step comprises providing a cured thermoplastic duct formed of a reinforced thermoplastic composite material.

3. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, wherein said heating step comprises heating the formation portion of the duct to a temperature of at least a glass transition temperature.

4. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, wherein said urging step comprises expanding the expansion member radially outward against the formation portion of the duct to urge the formation portion against the collar.

5. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 4, wherein said expanding step comprises adjusting a longitudinal width of a channel to compress the expansion member in the longitudinal direction and expand the expansion member radially outward.

6. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 4, wherein said urging step comprises delivering fluid to an inflatable bladder to inflate the bladder and expand the bladder radially outward against the formation portion of the duct.

7. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, wherein said urging step comprises expanding the expansion member radially inward against the formation portion of the duct to urge the formation portion against the inner support structure.

8. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, wherein said urging step comprises heating the expansion member to expand the expansion member radially to form the formation portion of the duct.

9. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, further comprising separably adjusting at least one portion of the collar to remove the duct therefrom.

10. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, wherein said heating step comprises electrically energizing at least one resistive heater to generate heat and conducting heat from the at least one heater to the formation portion of the duct.

11. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, further comprising, subsequent to said heating step and at least partially concurrent to said urging step, cooling the joint to a temperature at least less than a glass transition temperature.

12. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, further comprising providing the collar and the inner support structure, the collar extending longitudinally from a first end to a second end and having an inner surface extending at least partially between the first and second ends, the inner surface defining a cavity, the inner support structure extending longitudinally in the cavity and having an outer surface opposing the inner surface of the collar, the collar defining a mold contour, the expansion member being formed of an elastomeric material, the inner support structure defining a channel for receiving the expansion member, and a width of the channel being adjustable in the longitudinal direction of the collar to compress the expansion member in the longitudinal direction and urge the expansion member radially toward the mold contour such that the expansion member is configured to urge a formation portion of the duct against the mold contour and thereby thermoplastically form the duct.

13. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 12 wherein said heating step comprises providing a plurality of heaters extending at least partially through the inner support structure and configured to heat a formation portion of the duct to at least a formation temperature.

14. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1, further comprising providing the inner support structure, the inner support structure being a rigid structure extending longitudinally in a cavity of the collar and including first and second portions, the first portion defining a face having an aperture configured to at least partially and longitudinally receive the second portion, and at least one heater extending at least partially through the inner support structure and configured to be disposed within the passage of the duct.

15. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1 wherein said heating step comprises heating the duct with a plurality of heaters extending at least partially through said inner support structure.

16. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 1 wherein said heating step comprises heating the duct with at least one heater positioned radially outside the collar and configured to radiate heat radially inward to the duct.

17. A method of thermoplastically forming a contour in a thermoplastic duct, the method comprising:

configuring a rigid inner support structure to extend longitudinally in a passage of the duct such that a mold contour defined by an outer surface of the inner support structure and corresponding to a desired configuration of the duct is located proximate to a formation portion of the duct;

disposing heat shrinkable tape circumferentially around the formation portion of the duct; and

heating the heat shrinkable tape and at least a formation portion of the duct to at least a formation temperature, such that the tape contracts radially inward urging the formation portion of the duct radially against the mold contour and thermoplastically forming the duct.

18. A method of thermoplastically forming a contour in a thermoplastic duct according toclaim 17, further comprising adjusting a consolidation joining head radially inward against an interface portion of the duct defined by longitudinal edges of the duct to urge the interface portion against the inner support and heating the interface portion to at least a glass transition temperature, thereby consolidation joining the interface portion.

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