Patent Publication Number: US-2021187817-A1

Title: Reducing manufacturing defects of a wound filament product

Description:
FIELD OF THE DISCLOSURE 
     This disclosure relates to continuous fabrication methods, in particular, to filament winding. 
     BACKGROUND OF THE DISCLOSURE 
     Filament winding is a manufacturing process used to produce composite parts such as pipes or pressure vessels. The process includes dipping continuous fibers (for example, fiber filaments) in a matrix material and winding the fibers onto a mandrel. The fibers are wound until the surface of the mandrel is covered and the required thickness is achieved to form the final product. Manufacturing defects such as voids and uneven curing can affect the structural integrity and mechanical properties of the final product. 
     SUMMARY 
     Implementations of the present disclosure include a filament winding assembly that includes a rotating mandrel coupled to a shaft configured to rotate the rotating mandrel. The rotating mandrel includes a first perforated sleeve that defines holes and includes a winding surface. The rotating mandrel also includes a second perforated sleeve disposed inside the first perforated sleeve. The second perforated sleeve is attached to the shaft and defines an interior volume. The second perforated sleeve defines holes configured to form fluid pathways with the holes of the first perforated sleeve. The fluid pathways extend from the interior volume to the winding surface of the first perforated sleeve. The filament winding assembly also includes a filament configured to wound, under tension, around the winding surface of the first perforated sleeve. The filament winding assembly also includes a fluid source fluidically coupled to the interior volume of the second perforated sleeve. The fluid source is configured to exhaust fluid, through the fluid pathways, from the wound filament to reduce manufacturing defects of the wound filament. 
     In some implementations, the second perforated sleeve is configured to rotate with respect to the first perforated sleeve to align or misalign the holes of the second perforated sleeve with the holes of the first perforated sleeve to open or close the fluid pathways. The interior volume is open when the holes of the second perforated sleeve are aligned with the holes of the first perforated sleeve. The interior volume is at least partially closed when the holes of the second perforated sleeve are misaligned with respect to the holes of the first perforated sleeve. In some implementations, the fluid source is configured to vacuum, with the interior volume open, air from the wound filament to reduce voids in the wound filament. In some implementations, the fluid source or a different fluid source fluidically coupled to the interior volume is configured to flow, with the interior volume at least partially closed, steam into the interior volume to heat the rotating mandrel to help uniformly cure at least part of the wound filament. In some implementations, each hole of the second perforated sleeve is configured to align with each hole of the first perforated sleeve to form respective fluid pathways. In some implementations, the second perforated sleeve is tightly snug inside the first perforated sleeve to help prevent fluid from flowing between an outer surface of the second perforated sleeve and an inner surface of the first perforated sleeve. In some implementations, the mandrel includes a lock attached to the first perforated sleeve and the second perorated sleeve. The lock is actuable to prevent rotation of the second perforated sleeved with respect to the first perforated sleeve and actuable to allow rotation of the second perforated sleeved with respect to the first perforated sleeve. 
     In some implementations, the second perforated sleeve includes a first closed end opposite a second closed end. At least one of the first closed end or the second closed end is attached to the shaft to rotate the rotating mandrel. 
     In some implementations, the first perforated sleeve is a first perforated tube and the second perforated sleeve is a second perforated tube. The second perforated tube is axially coupled to the shaft. The second perforated tube and the first perforated tube are configured to rotate together with the shaft during winding of the filament. 
     In some implementations, the fluid source is configured to vacuum, with the interior volume open, air from the wound filament during a manufacturing process when the filament is being wound on the mandrel. 
     In some implementations, the shaft is a hollow shaft including apertures. The hollow shaft defines a second interior volume fluidically coupled, through the shaft apertures, to the interior volume of the second perforated sleeve. The fluid source is fluidically coupled, through a fluid conduit extending through the second interior volume of the hollow shaft, to the interior volume of the second perforated sleeve. 
     Implementations of the present disclosure include a method that includes winding, under tension and by a filament winding assembly, an impregnated filament on a winding surface of a rotating mandrel. The rotating mandrel includes 1) a first perforated sleeve defining holes and including the winding surface, and 2) a second perforated sleeve disposed inside the first perforated sleeve. The second perforated sleeve defines an interior volume and defining holes configured to form fluid pathways with the holes of the first perforated sleeve. The method also includes exhausting, by a fluid source of the filament winding assembly that is fluidically coupled to the interior volume, air through the fluid pathways from the winding surface of the first perforated sleeve to reduce manufacturing defects of the wound filament. 
     In some implementations, the second perforated sleeve is rotatable with respect to the first perforated sleeve to align or misalign the holes of the second perforated sleeve with the holes of the first perforated sleeve to open or close the fluid pathways. The interior volume is open when the holes of the second perforated sleeve are aligned with the holes of the first perforated sleeve and the interior volume is at least partially closed when the holes of the second perforated sleeve are misaligned with respect to the holes of the second perforated sleeve. In such implementations, the method also includes, with the interior volume closed, flowing fluid, by the fluid source or a different fluid source fluidically coupled to the interior volume, steam into the interior volume to heat the rotating mandrel to help uniformly cure at least part of the wound filament. In some implementations, rotating the second perforated sleeve with respect to first perforated sleeve includes rotationally unlocking the first perforated sleeve from the second perforated sleeve, rotationally locking the first perforated sleeve, and rotating the second perforated sleeve with respect to the first perforated sleeve. 
     In some implementations, exhausting the air through the fluid pathways includes vacuuming air from the wound filament to reduce voids in the wound filament. 
     Implementations of the present disclosure also feature a filament winding mandrel that includes a first perforated sleeve defining holes and including a winding surface. The mandrel also includes a second perforated sleeve disposed inside the first perforated sleeve. The second perforated sleeve is attached to a rotating shaft configured to rotate the filament winding mandrel. The second perforated sleeve defines an interior volume and defines holes configured to form fluid pathways with the holes of the first perforated sleeve. The fluid pathways extend from the interior volume to the winding surface of the first perforated sleeve. The second perforated sleeve is configured to be fluidically coupled to a fluid source configured to exhaust fluid, through the fluid pathways, from the winding surface of the first perforated sleeve to reduce manufacturing defects of a filament wound on the winding surface of the first perforated sleeve. 
     In some implementations, the second perforated sleeve is configured to rotate with respect to the first perforated sleeve to align or misalign the holes of the second perforated sleeve with the holes of the first perforated sleeve to open or close the fluid pathways. The interior volume is open when the holes of the second perforated sleeve are aligned with the holes of the first perforated sleeve and the interior volume is at least partially closed when the holes of the second perforated sleeve are misaligned with respect to the holes of the second perforated sleeve. In some implementations, each hole of the second perforated sleeve is configured to align with each hole of the first perforated sleeve to form respective fluid pathways. In some implementations, the second perforated sleeve is tightly snug inside the first perforated sleeve to help prevent fluid from flowing between an outer surface of the second perforated sleeve and an inner surface of the first perforated sleeve. In some implementations, the first perforated sleeve is a first perforated tube and the second perforated sleeve is a second perforated tube. The second perforated tube is axially coupled to the shaft. The second perforated tube and the first perforated tube are configured to rotate together with the shaft during winding of the filament. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front schematic view of a filament winding assembly. 
         FIG. 2  is a schematic cross-sectional view of a mandrel of the filament winding assembly of  FIG. 1 , taken along line  2 - 2  in  FIG. 1 . 
         FIG. 3  is a perspective schematic view of a portion of a mandrel. 
         FIG. 4  is a perspective front view of the portion of the mandrel of  FIG. 3 , with an interior volume of the mandrel open. 
         FIG. 5  is a perspective front view of the portion of the mandrel of  FIG. 3 , with the interior volume of the mandrel closed. 
         FIG. 6  is a flow chart of an example method of manufacturing composite parts. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The present disclosure describes filament winding methods and equipment that reduce manufacturing defects of composite products. A mandrel that is made of two concentric perforated tubes can close and open the interior volume of the mandrel. The perforated tubes have corresponding holes that form fluid pathways that extend from the interior volume. The perforated tubes can rotate with respect to each other to align or misalign their respective holes, opening and closing the fluid pathways. With the interior volume open, air can be vacuumed from the wound filament to reduce or eliminate voids and other manufacturing defects. With the interior volume closed, steam can be injected into the mandrel to partially and uniformly cure the wound filament. 
     Particular implementations of the subject matter described in this specification can be implemented so as to realize one or more of the following advantages. For example, vacuuming air out of the wound product can reduce voids and other manufacturing defects, improving the structural integrity of the final product. Injecting steam into the mandrel partially cures the composite product, allowing the product to be removed from the mandrel for additional processing. In addition, the mandrel of the present disclosure allows in-situ vacuuming and partially curing of the wound product, without moving the mandrel or the wound product to a different station. Additionally, the mandrel of the present disclosure can be used in helical winding machines and polar winding machines. The filament winding assembly or system of the present disclosure allows removing the trapped air from the wound product followed by steam injection, combining the advantages of both processes to allow easy composite part removal. 
       FIG. 1  shows a filament winding assembly  100  that includes a rotating mandrel  102  (for example, a mold core), a rotatable shaft  104 , a filament winding rig  103 , and at least one fluid source  112  fluidically coupled to the mandrel  102 . The mandrel  102  is axially coupled to the shaft  104  that rotates the mandrel  102  about a longitudinal axis ‘L’. The shaft  104  is rotationally coupled to the filament winding rig  103 . The rotating mandrel  102  includes a first perforated sleeve  106  with an exterior, winding surface  107  (for example, the winding surface of the mandrel). A continuous filament  116  is wound, under tension, on the winding surface  107  of the first perforated sleeve  106 . The filament  116  can be, for example, carbon fibers, glass fibers, or aramid fibers, such as the Kevlar® fibers provided by DuPont™, located in Midland, Mich., USA. The filament  116  is impregnated on a matrix material (for example, an epoxy resin) before winding the filament  116  on the mandrel  102 . After the filament  116  is wound on the mandrel  102  to a desired thickness, the wound filament  116  is further processed (for example, removed from the mandrel for additional processing steps) to form the final product. 
     The mandrel  102  also includes a second perforated sleeve  108  disposed inside the first perforated sleeve  106 . The second perforated sleeve  108  is attached to the rotating shaft  104  to rotate with the rotating shaft  104 . The second perforated sleeve  108  defines an interior volume  115  fluidically coupled, through a fluid conduit  114 , to the fluid source  112 . The fluid conduit  114  extends away from the mandrel  102  and can deliver fluid into the interior volume  115  or receive fluid from the interior volume  115 . 
     The fluid source  112  can be or include a vacuum source (for example, a vacuum pump) and a steam source (for example, a steam pump). In some implementations, as shown in  FIG. 1 , the fluid source  112  can only be a vacuum source and a second fluid source  110  fluidically coupled to the interior volume  115  can include the steam source. For example, the first fluid source  112  can be fluidically coupled, through a three-way valve  120 , to the second fluid source  110 . The first fluid source  112  and second fluid source  110  can be fluidically coupled, through the common fluid conduit  114 , to the interior volume  115  of the second perforated sleeve  108 . As further described in detail later with respect to  FIGS. 3-5 , the first fluid source  112  can vacuum or exhaust air  124  from the winding surface  107  (for example, from the wound filament  116 ) and the second fluid source  110  can inject steam  122  into mandrel  102  to at least partially cure the wound filament  116 . Vacuuming air from the filament  116  as the filament  116  is being wound (for example, during the manufacturing process) can help reduce voids and other manufacturing defects of the final product. One cause for void formation is the release of air or gases from the epoxy resin during curing. The air can be trapped in the resin during the winding process and if the air is not released prior to curing, the formed voids can compromise the structural integrity of the final product. Additionally, injecting steam into the same mandrel  102  (for example, after winding) can help uniformly cure the wound filament  116  to reduce manufacturing defects of the final product. 
     The mandrel  102  includes a first closed end  131  opposite a second closed end  133  to prevent fluid (for example, steam) from leaving the interior volume  115  through the ends  131  and  133  of the mandrel  102 . At least a portion of the rotating shaft  104  can be hollow to receive a portion of the fluid conduit  114 . The fluid conduit  114  can extend from an aperture of the rig  103 , through the hollow shaft  104 , and into the mandrel  102 . The portion of the shaft  104  inside the mandrel  102  can be hollow and include holes or apertures  113  that fluidically couple the interior of the shaft  104  to the interior volume  115  of the mandrel  102 . For example, the shaft  104  defines a second interior volume  117  fluidically coupled, through the shaft apertures  113 , to the interior volume  115 . Thus, fluid can flow from the interior volume  115  to the fluid conduit  114  through the interior volume  117  of the rotating shaft  104 , and from the fluid conduit  114  to the interior volume  115  of the mandrel  102  through the interior volume  117  of the shaft  104 . 
       FIG. 2  shows a cross-sectional view of the mandrel  102  taken along line  2 - 2  in  FIG. 1 . The first and second perforated sleeves  106  and  108  of the mandrel  102  can be concentric tubes that rotate together when winding the filament. The second perforated sleeve  108  of the mandrel  102  is tightly snug inside the first perforated sleeve  106  to help prevent fluid from flowing (for example, flowing laterally) between an outer surface  109  of the second perforated sleeve  108  and an inner surface  105  of the first perforated sleeve  106 . For example, the radius or diameter of the perforated sleeves  106  and  108  can have tight tolerances (for example, 0.0001 to 0.1 mm) to help prevent fluid from flowing laterally between the two sleeves. As further described in detail later with respect to  FIGS. 3-5 , respective holes  140  and  142  of the rotating sleeves align with each other to form fluid pathways. 
     The second perforated sleeve  108  has a cap  139  at each end  131  and  133  of the perforated sleeve  108  to help prevent steam from leaving the interior volume  115  and to help prevent air from entering the interior volume  115  from the sides of the mandrel  102 . The first perforated sleeve  106  can also have a cap at each end of the mandrel  102  to help prevent steam from leaving mandrel  102  and to help prevent air from entering the interior volume  115  from the sides of the mandrel  102 . To prevent the sleeves  106  and  108  from rotating with respect to each other during winding, both sleeves  106  and  108  can be connected by a lock  138  fixed to the caps of each perforated sleeve  106  and  108 . The lock  138  can be manually or automatically actuated to lock and unlock the sleeves  106  and  108  to prevent and allow the sleeves from rotating with respect to each other. For example, during winding, both sleeves  106  and  108  are rotationally locked with respect to each other to rotate together with the shaft  104 , and before injecting steam into the interior volume  115 , the lock can disengage the sleeves  106  and  108  to rotate the sleeves and close the interior volume  115 . The rotating shaft  104  is a concentric shaft attached, through wings  130  or rods, to an inside surface  111  of the second perforated sleeve  106  to rotate the mandrel  102 . 
       FIG. 3  shows a portion of the rotating mandrel  102 . The first perforated sleeve  106  of the mandrel  102  defines multiple perforations or holes  140  along the length (for example, on the curved surface) of the perforated sleeve  106 . The holes  140  extend from the winding surface  107  of the sleeve  106  to the inner surface  105  of the sleeve  106 . The holes of the first perforated sleeve  106  (and the second perforated sleeve  108 ) can have a diameter, for example, of between 3.37×10 −5  to 0.338 millimeters. Each perforated sleeve can have, for example, between 10 to 500 holes per square meter. Similar to the first perforated sleeve  106 , the second perforated sleeve  108  has holes  142  that extend from the outer surface  109  of the sleeve  108  to the inside surface  111  of the sleeve  108 . 
     Referring also to  FIG. 4 , the holes  142  of the second perforated sleeve  108  correspond with the holes  140  of the first perforated sleeve  106  to form fluid pathways  150  that open the interior volume  115  to the exterior surface of the mandrel  102 . For example, the holes  142  of the second perforated sleeve  108  form respective fluid pathways  150  with the holes  140  of the first perforated sleeve  106  when the holes  142  of the second perforated sleeve  108  are aligned with the holes  140  of the first perforated sleeve  106 . The fluid pathways  150  extend from the interior volume  115  of the second perforated sleeve  108  to the winding surface  107  of the first perforated sleeve  106 . 
     As shown in  FIGS. 4 and 5 , the second perforated sleeve  108  rotates with respect to the first perforated sleeve  106  to align or misalign the holes  142  of the second perforated sleeve  108  with the holes  140  of the first perforated sleeve  106  to open or close the fluid pathways  150 . For example, each hole  142  of the second perforated sleeve  108  is arranged to align with each hole  140  of the first perforated sleeve  106  to form respective fluid pathways  150 . The interior volume  115  is open when the holes  142  of the second perforated sleeve  108  are aligned with the holes  140  of the first perforated sleeve  106  and the interior volume 115  is at least partially closed when the holes  142  of the second perforated sleeve  108  are misaligned or offset with respect to the holes  140  of the first perforated sleeve  106 . To rotate the second perforated sleeve  108  with respect to first perforated sleeve  106 , the first perforated sleeve  106  can be rotationally locked while a hydraulic system (not shown) rotates the second perforated sleeve  108 . 
     As shown in  FIG. 4 , the fluid source  112  (see  FIG. 1 ) vacuums, through the interior volume (and with the interior volume open), air from the wound filament to reduce voids in the wound filament. As shown in  FIG. 5 , the fluid source  112  ora different fluid source  110  fluidically coupled to the interior volume  115  flows, with the interior volume  115  at least partially closed, steam  122  into the interior volume  115  to heat the rotating mandrel  102  to help uniformly cure at least part of the wound filament. 
       FIG. 6  shows a flowchart of an example method  600  that includes winding, under tension and by a filament winding assembly, an impregnated filament on a winding surface of a rotating mandrel, the rotating mandrel including 1) a first perforated sleeve defining holes and including the winding surface, and 2) a second perforated sleeve disposed inside the first perforated sleeve, the second perforated sleeve defining an interior volume and defining holes configured to form fluid pathways with the holes of the first perforated sleeve ( 605 ). The method also includes exhausting, by a fluid source of the filament winding assembly and fluidically coupled to the interior volume, air through the fluid pathways from the wound filament to reduce manufacturing defects of the wound filament ( 610 ). 
     Although the following detailed description contains many specific details for purposes of illustration, it is understood that one of ordinary skill in the art will appreciate that many examples, variations and alterations to the following details are within the scope and spirit of the disclosure. Accordingly, the exemplary implementations described in the present disclosure and provided in the appended figures are set forth without any loss of generality, and without imposing limitations on the claimed implementations. 
     Although the present implementations have been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the disclosure. Accordingly, the scope of the present disclosure should be determined by the following claims and their appropriate legal equivalents. 
     The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise. 
     As used in the present disclosure and in the appended claims, the words “comprise,” “has,” and “include” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps. 
     As used in the present disclosure, terms such as “first” and “second” are arbitrarily assigned and are merely intended to differentiate between two or more components of an apparatus. It is to be understood that the words “first” and “second” serve no other purpose and are not part of the name or description of the component, nor do they necessarily define a relative location or position of the component. Furthermore, it is to be understood that that the mere use of the term “first” and “second” does not require that there be any “third” component, although that possibility is contemplated under the scope of the present disclosure.