PATENT DOCUMENT

Publication Number: US-8888940-B2
Application Number: US-201113049093-A
Country: US
Kind Code: B2

Title: Methods for forming composite housing frames

Abstract:
Electronic device frames may be formed from fiber composites. Carbon fiber material may be formed into frame members using pultrusion tools. Notches may be machined into the frame members. The machined frame members may be assembled to form a rectangular frame assembly using lap joints. Fiber tape may be wound around the periphery of the frame assembly. Following curing, additional parts such as a metal blank may be bonded to the frame assembly and machined.

Claims:
What is claimed is: 
     
       1. A method for forming an electronic device frame, comprising:
 forming frame members; 
 assembling the frame members to form a rectangular frame assembly for an electronic device; and 
 with a winding tool, winding fiber tape around the rectangular frame assembly, 
 wherein the fiber tape is formed from a continuous piece of binder preimpregnated tape wrapped around the winding tool. 
 
     
     
       2. The method defined in  claim 1  wherein forming the frame members comprises forming elongated frame members with a pultrusion tool. 
     
     
       3. The method defined in  claim 1  wherein forming the frame members comprises forming carbon fiber frame members. 
     
     
       4. The method defined in  claim 3  wherein assembling the frame members comprises attaching the frame members to each other using lap joints and adhesive. 
     
     
       5. The method defined in  claim 4  further comprising forming notches at ends of the frame members. 
     
     
       6. The method defined in  claim 5  further comprising heating the frame members of the rectangular frame assembly and the wound fiber tape to form a unitary fiber composite frame structure. 
     
     
       7. The method defined in  claim 6  further comprising attaching a metal blank to the unitary fiber composite frame structure. 
     
     
       8. The method defined in  claim 7  further comprising machining the metal blank. 
     
     
       9. The method defined in  claim 8  further comprising machining the unitary fiber composite frame structure. 
     
     
       10. The method defined in  claim 1 , further comprising attaching a metal blank to at least one of the frame members forming the rectangular frame assembly. 
     
     
       11. The method defined in  claim 10 , wherein the attaching of the metal blank comprises bonding an aluminum blank to the at least one of the frame members forming the rectangular frame assembly using adhesive. 
     
     
       12. the method defined in  claim 1 , wherein the frame members forming the rectangular frame assembly each include a longitudinal axis. 
     
     
       13. The method defined in  claim 12 , wherein the winding of the fiber tape around the rectangular frame assembly comprises:
 coupling the fiber tape to one of, a distinct frame member forming the rectangular frame assembly, or fiber tape wound around the distinct frame member forming the rectangular frame assembly, 
 wherein the fiber tape is in parallel alignment with the longitudinal axis of the distinct frame member forming the rectangular frame assembly. 
 
     
     
       14. The method defined in  claim 1 , further comprising curing at least one of the fiber tape, and the frame members forming the rectangular frame assembly. 
     
     
       15. The method defined in  claim 1 , wherein the substantially rectangular frame assembly for the electronic device includes substantially rounded corners. 
     
     
       16. A method for forming an electronic device frame, comprising:
 forming carbon fiber frame members; 
 forming notches at ends of the carbon fiber frame members; 
 assembling the carbon fiber frame members to each other using lap joints and adhesive to form a frame assembly; and 
 with a winding tool, winding fiber tape around the frame assembly. 
 
     
     
       17. The method defined in  claim 16  further comprising heating the frame members of the frame assembly and the wound fiber tape to form a unitary fiber composite frame structure. 
     
     
       18. The method defined in  claim 17  further comprising attaching a metal blank to the unitary fiber composite frame structure. 
     
     
       19. The method defined in  claim 18  further comprising machining the metal blank. 
     
     
       20. The method defined in  claim 17  further comprising machining the unitary fiber composite frame structure.

Description:
This application claims the benefit of provisional patent application No. 61/376,673 filed Aug. 24, 2010, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates to electronic devices such as computers, and more particularly, to housing structures for electronic devices. 
     Electronic devices such as cellular telephones, tablet computers, and laptop computers include housings. Typical housing structures are formed from plastic and metal. Some housing structures use fiber composites. 
     A typical electronic device housing forms a recess into which device components are mounted. In some devices, housings that contain displays are surrounded by metal bezels and metal bands. 
     In an effort to reduce weight, it may be desirable to minimize the use of metal housing structures. Unreinforced plastic parts may be lighter than metal, but are vulnerable to damage when a device is dropped or subjected to other unintended impact events. 
     Sheets of fiber composite material may exhibit satisfactory strength for forming an electronic device housing and may exhibit relatively low weight. Nevertheless, if care is not taken, fiber composite housing structures will not be aesthetically appealing, will be vulnerable to impact damage, and will not interface well with other housing structures in an electronic device. 
     It would therefore be desirable to be able to provide improved housing structures for electronic devices such as fiber-based housing structures. 
     SUMMARY 
     Fiber-based composites may be used in forming frames for electronic devices. The frames may be used in mounting planar device structures such as displays and rear housing plates. 
     The frames may be formed by winding tape around a mandrel and curing the wound tape. Grooves may be machined in the cured tape to form a frame. A metal blank such as an aluminum blank may be bonded to the frame and machined to form a finished frame. 
     The frames may also be formed from elongated frame members. A machining tool may be used to machine notches in the ends of the frame members. The notched frame members may be attached to one another at right angles using lap joints to form a four-sided rectangular frame assembly. Fiber tape may be wound around the frame assembly to form a hoop that encircles the frame assembly. A curing process may be used to co-cure the wound fiber tape and the frame members of the frame assembly to form a unitary fiber composite structure. A finished frame may be formed by bonding a metal blank to the unitary fiber composite structure and machining the blank and the composite frame. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a portable computer in accordance with an embodiment of the present invention. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a cellular telephone or other handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer in accordance with an embodiment of the present invention. 
         FIG. 4  is a cross-sectional side view of an electronic device having a peripheral housing member such as a bezel-shaped frame that runs around the upper periphery of the device sidewalls while leaving lower sidewall portions exposed in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of an electronic device having a peripheral housing member such as a rectangular frame with an L-shaped cross section in accordance with an embodiment of the present invention. 
         FIG. 6  is a cross-sectional side view of an electronic device having a peripheral housing member such as a rectangular frame with a T-shaped cross section forming vertical sidewalls and a horizontal shelf portion for mounting display structures and a rear housing plate in accordance with an embodiment of the present invention. 
         FIG. 7A  is a perspective view of an illustrative frame having a T-shaped cross section in accordance with an embodiment of the present invention. 
         FIG. 7B  is a cross-sectional side view of one of the edges of the frame of  FIG. 7A  in accordance with an embodiment of the present invention. 
         FIG. 8  is a top view of one of the corners of an illustrative rectangular frame with a cross-sectional shape such as a T-shape showing how fibers within the frame may be oriented so as to run parallel to the sides of the frame in accordance with an embodiment of the present invention. 
         FIG. 9  is a perspective view of a piece of fiber tape such as carbon fiber prepreg tape in accordance with an embodiment of the present invention. 
         FIG. 10  is a top view of an illustrative winding system showing how fiber tape may be wound around a mandrel to form a frame structure with fibers oriented parallel to the sides of the frame as shown in  FIG. 8  in accordance with an embodiment of the present invention. 
         FIG. 11  is a perspective cross-sectional view of a portion of a frame structure formed using a winding apparatus of the type shown in  FIG. 10  in accordance with an embodiment of the present invention. 
         FIG. 12  is a diagram showing how a machining tool may machine grooves in a frame structure of the type shown in  FIG. 11  to form a rectangular frame with a T-shaped cross-sectional shape of the type shown in  FIGS. 7A and 7B  in accordance with an embodiment of the present invention. 
         FIG. 13  is a perspective cross-sectional view of a portion of a frame of the type shown in  FIGS. 7A and 7B  that has been formed using a machining tool of the type shown in  FIG. 12  in accordance with an embodiment of the present invention. 
         FIG. 14  is a diagram showing illustrative equipment that may be used in forming a frame of the type shown in  FIGS. 7A and 7B  in accordance with an embodiment of the present invention. 
         FIG. 15  is a flow chart of illustrative steps involved in forming a frame using equipment of the type shown in  FIG. 14  in accordance with an embodiment of the present invention. 
         FIG. 16  is an exploded perspective view of two illustrative frame member having notches for forming a lap joint in accordance with an embodiment of the present invention. 
         FIG. 17  is a perspective view of a corner portion of an illustrative frame that has been formed from an assembly with frame members that are attached to each other using lap joints around which layers of fiber tape have been wound in accordance with an embodiment of the present invention. 
         FIG. 18  is a perspective view showing how fiber composite frame members such as frame members with a T-shaped cross-section may be formed using a tool such as pultrusion tool in accordance with an embodiment of the present invention. 
         FIG. 19  is a top view showing how a winding tool may be used to wind fiber tape around a frame assembly formed from lap-jointed pultrusion frame members in accordance with an embodiment of the present invention. 
         FIG. 20  is an exploded perspective view of two notched frame members having T-shaped cross sections that are being attached to each other using a lap joint in accordance with an embodiment of the present invention. 
         FIG. 21  is a perspective cross-sectional view of a portion of a frame that has been formed from T-shaped pultrusion frame members around which layers of fiber tape have been wound in accordance with an embodiment of the present invention. 
         FIG. 22  is a diagram showing illustrative equipment that may be used in forming a frame or other housing structure for an electronic device that includes co-cured pultrusion structures and wound fiber structures in accordance with an embodiment of the present invention. 
         FIG. 23  is a flow chart of illustrative steps that may be used in forming a frame using equipment of the type shown in  FIG. 22  in accordance with an embodiment of the present invention. 
         FIG. 24  is a perspective view of an illustrative frame structure formed from T-shaped pultrusion frame members around which layers of fiber tape have been wound in accordance with an embodiment of the present invention. 
         FIG. 25  is a perspective view of an illustrative frame structure of the type shown in  FIG. 24  following bonding of a blank of material such as metal in accordance with an embodiment of the present invention. 
         FIG. 26  is a perspective view of a finished frame for an electronic device that has been formed by machining the unfinished frame assembly of  FIG. 25  in accordance with an embodiment of the present invention. 
         FIG. 27  is a flow chart of illustrative steps involved in forming a frame for an electronic device by attaching a hoop-shaped frame structure such as a wound tape ring to a frame assembly such as a rectangular structure formed from four elongated frame members using adhesive in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     This relates to structures for electronic devices such as housing structures formed from composite materials. The composite materials may include one or more types of fiber bound together using a binder. Housing structures and other device structures formed from the composite materials may therefore sometimes be referred to as fiber-based composites or fiber composites. Examples of fiber-based composites include carbon fiber composites and fiberglass. 
     In general, any types of fibers and binders may be used in the composite materials. The fibers may, for example, include metal fibers (e.g., strands of steel or copper), glass fibers, plastic fibers (e.g., polymers such as aramid fibers, nylon, etc.), carbon fibers, nanotubes, etc. These fibers may be relatively thin (e.g., less than 20 microns or less than 5 microns in diameter as with some carbon nanotubes and carbon fibers) or may be thicker (e.g., metal wire). The fibers may be individual fibers or may be twisted bundles of smaller fibers (sometimes referred to as filaments). Regardless of their individual makeup (i.e. whether thick, thin, or twisted or otherwise formed from smaller fibers), the strands of material that are incorporated into the composite materials may be referred to herein as fibers. 
     Binder can be incorporated into fiber structures to provide these structures with rigidity and other suitable properties. The binder, which is sometimes referred to as a matrix, may be formed from epoxy or other suitable materials. These materials may sometimes be categorized as thermoset materials (e.g., materials such as epoxy that are formed from a resin that cannot be reflowed upon reheating) and thermoplastics (e.g., materials such as acrylonitrile butadiene styrene, polycarbonate, and ABS/PC blends that are reheatable). Both thermoset materials and thermoplastics and combinations of thermoset materials and thermoplastic materials may be used as binders for the composite materials if desired. 
     The electronic devices in which the composite materials are used may be tablet computers, cellular telephones and other handheld electronic devices, portable computers, other portable electronic devices, computer monitors, computer monitors with embedded computers, televisions, and other electronic equipment. In a typical configuration, the electronic device may be a portable computer, a handheld device such as a cellular telephone, or a tablet computer, so examples of these devices are sometimes described herein. This is, however, merely illustrative. Composite materials may be used in forming housing structures for any suitable electronic devices if desired. Moreover, housing structures formed from composite materials may, if desired, incorporate non-composite materials such as plastic, glass, metal, ceramic, etc. As an example, metal, glass, plastic, and ceramic structures may be attached to composite housing structures using screws and other fasteners, using adhesive such as pressure sensitive adhesive, using clips and other engagement structures, etc. 
       FIG. 1  is a perspective view of an illustrative electronic device such as a portable computer. As shown in  FIG. 1 , device  10  may have a housing  12 . Housing  12  may include upper housing portion  12 A and lower housing portion  12 B. Housing portions  12 A and  12 B may be connected using hinge structures in region  20  (sometimes referred to as a clutch barrel or clutch barrel structures). The hinges in clutch barrel  20  may allow upper housing  12 A to rotate relative to lower housing  12 B about rotational axis  22  in directions  24 . 
     Lower housing  12 B, which may sometimes be referred to as a base or base unit, may include components such as keyboard  16  and pointing device  14 . Pointing device  14  may be a track pad and may have associated buttons. Input-output ports may be provided in the housing for main unit  12 B. The interior of main unit  12 B may include components such as a main logic board, peripheral cards, a battery, communications circuits and busses, wireless transceiver circuitry, etc. 
     Upper housing  12 A, which may sometimes be referred to as a display housing, may include display  18 . Upper housing  12 A may also include other electrical components. These components may be mounted within clutch barrel  20 , behind display  18 , or in the peripheral region surrounding the outer periphery of display  18 . 
     Display  18  may have four peripheral edges (e.g., left edge  18 L, right edge  18 R, top edge  18 T, and bottom edge  18 B). These edges may be surrounded by one or more housing structures. For example, the edges of display  18  may be surrounded by peripheral housing member  26 . Housing member  26  may, for example, have a rectangular ring shape with four elongated sides. Display  18  may have a cover glass plate or other planar display structures that are mounted on the front surface of display housing  12 A (i.e., the side of housing  12 A that is visible in the example of  FIG. 1 ). A planar sheet material (e.g., a rear plate) may be nested within a groove in the rear side of housing member  26  (i.e., on the side of display housing  12 A opposite to that of display  18 ). 
     Peripheral housing member  26  or part of member  26  may serve as a cosmetic bezel (e.g., a bezel for display  18 ) or as a cosmetic trim structure. Peripheral housing member  26  may also serve as a structural support onto which other housing structures may be mounted. Peripheral housing member  26  of device  10  of  FIG. 1  (and the other illustrative electronic devices described herein) may therefore sometimes be referred to herein as a frame or support structure. 
     Some of frame  26  may be external. For example, frame  26  may have surfaces that are exposed along the front and rear faces of display housing  12 A and surfaces that are exposed and form sidewalls around the upper, lower, left, and right edges of display housing  12 A. In some arrangements, some or all of frame  26  may be mounted internally, within the interior of device  10 . Examples in which frame  26  has external surfaces are sometimes described herein as an example. In general, however, frame  26  may be an external frame (i.e., a frame with at least some external surfaces and some internal surfaces) or an internal frame (i.e., a frame that is enclosed within the interior of the housing of device  10 ). Frame  26  may cover substantially all of the sidewalls of display housing  12 A or may be provided in the form of a bezel that surrounds the front of display housing  12 A while leaving the rear portions of the display housing sidewalls uncovered. 
       FIG. 2  is a perspective view of a handheld electronic device. As shown in  FIG. 2 , electronic device  10  of  FIG. 2  may have a display such as display  18  that is mounted on the front of device  12 . Device  10  may be, for example, a cellular telephone, media player, or other handheld device. Opening  28  may form a speaker port for a cellular telephone ear speaker and buttons such as button  30  may serve as user input devices for device  10 . Display  18  may be a touch screen display. Housing  12  may include a peripheral housing member such as frame  26 . Frame  26  may be formed from a band-shaped member that surrounds the four peripheral edges of display  18 . Frame  26  may also form a bezel that runs around the top part of the sidewalls of device  10  while leaving the lower sidewalls of device  10  uncovered. 
       FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer. As shown in  FIG. 3 , housing  12  may include a peripheral housing member such as frame  26  that surrounds the four peripheral edges of display  18 . Button  30  may be used to supply user input to device  10 . Frame  26  may be implemented as a band-shaped member that covers all of the sidewalls of device  10  (i.e., extending from the front face that includes display  18  to the rear face of device  10  on the opposite side from display  18 ) or may be implemented as a bezel member that runs around the periphery of display  18  near the front face of device  10  while leaving the rear portions of the sidewalls of device  10  uncovered. 
       FIG. 4  is a cross-sectional side view of an illustrative arrangement for device  10  showing how device  10  may have a bezel-shaped frame  26  that surrounds display  18  near the front face of device  10  while leaving housing sidewalls such as housing sidewalls  12 SW substantially uncovered. Internal device components  28  may be mounted on housing rear wall  12 R in the interior of device  10 . 
     In the  FIG. 5  example, frame  26  of device  10  has an L-shaped cross section having vertical sidewall portions  26 S and rear wall portion  26 R. Rear housing wall  12 R may be mounted to rear wall portion  26 R of frame  26 . Interior components  28  may be mounted in the interior of device  10 . Display  18  may be mounted on the front face of device  10  and may have four peripheral edges that are surrounded by frame  26 . 
     As shown in  FIG. 6 , device  10  may have a frame with a T-shaped cross section. The stem of the T may form shelf portion  32  of frame  26 . The top of the T (i.e., vertical frame portion  38 ) may form vertical sidewalls for frame  26  that surround display  18 . Display  18  may be mounted on upper shelf surface  34  of shelf portion  32  using adhesive  30 . Rear housing plate  12 R may be a rectangular plate of glass, ceramic, metal, plastic, composite, other materials, or layers or other combinations of these materials. Rear housing plate  12 R may be mounted to lower shelf surface  36  of frame shelf  32  using adhesive  30 . 
       FIG. 7A  is a perspective view of an illustrative arrangement that may be used for frame  26 . As shown in  FIG. 26 , frame  26  may have the shape of a rectangular ring. Vertical sidewall portions  38  may run around the outside of shelf portion  32 . A cross-sectional view of frame  26  taken along line  42  and viewed in direction  40  of  FIG. 7A  is shown in  FIG. 7B . 
     In general, frame  26  may be formed from metal, glass, ceramic, plastic, composites, other materials, and combinations of these materials. With one suitable arrangement, at least part of frame  26  is formed from fiber-based composites to reduce weight while maintaining satisfactory strength and/or to increase strength. 
     To ensure that frame  26  and device  10  are resistant to damage when dropped or subjected to other impact events, it may be desirable to run the fibers in frame  26  smoothly around frame corners. An example of this type of arrangement is shown in  FIG. 8 . In the  FIG. 8  example, one of the four corners of frame  26  of  FIG. 7A  is shown in a top view. The solid lines in  FIG. 8  correspond to the inner and outer periphery of the frame (lines  46  and  44 , respectively) and the division between vertical sidewall portion  38  and shelf  32  (line  48 ). Dashed lines  50  are aligned with the longitudinal axes of the fibers in shelf portion  32  of frame  26 , whereas dashed lines  52  run parallel to the fiber axes of the fibers in vertical sidewall portion  38  of frame  26  (see, e.g.,  FIG. 7A ). 
     By orienting the fibers of frame  26  so that they run parallel to the outer peripheral wall  44  of vertical frame portion  38  and the inner wall  46  of frame shelf  32 , the fibers will be perpendicular to edge impacts in directions such as direction  54  and  56 . The fibers will also be perpendicular to a corner impact in direction  58 . Fibers oriented perpendicular to the direction of impact in this way will tend to maximize frame strength and thereby help to prevent damage to device  10  in the event of a drop event or other unintended impact. Wrapping the fibers of the frame in a rectangular ring shape so that the fibers run parallel to the edges of the frame may also help to distribute stresses along the fibers, spreading out loads. This tends to reduce the peak load that is experienced during a drop event, helping to protect internal components  28 , display  18 , and rear plate  12 R. 
     A frame structure with a fiber orientation of the type shown in  FIG. 8  may be formed by wrapping fiber tape that has been preimpregnated with binder (sometimes referred to as fiber prepreg or prepreg tape) around a mandrel in a tape winding tool.  FIG. 9  is a perspective end view of a piece of illustrative prepreg tape. Prepreg tape  60  of  FIG. 9  may have a width W, a thickness T, and a length L. The width W may be, for example, 0.1 to 10 mm or more (or less). The thickness T may be about 0.02 to 3 mm or more (or less). The value of L may be meters or longer prior to cutting (determined by the size of the storage spool from which tape  60  is dispensed). 
       FIG. 10  shows how tape  60  may be wound around mandrel  62  in direction  68  using dispensing rollers  64 . Tape  60  may be dispensed from spool  66 . Rollers  64  may be moved completely around the periphery of mandrel  62  one or more times (or the mandrel may be moved), until a desired number of tape layers have been formed for frame  26  (see, e.g., the illustrative tape layers  60  of frame portion  70  of  FIG. 11 ). 
     Following curing, machining tool  72  may use computer-controlled positioners  74  and rotating cutting heads  76  or other machining equipment to remove undesired portions of frame structure  70 , as shown in  FIG. 12 . In the example of  FIG. 12 , grooves  78  are being removed. Other features may be machined into frame structure  70  if desired. 
     Following machining operations with tool  72 , frame structure  70  of  FIG. 12  is transformed into frame structure  26  of  FIG. 13 . As shown in  FIG. 13 , frame  26  may be formed from numerous layers of fiber tape  60 . The lateral dimension of tape  60  (i.e., width W of  FIG. 9 ) may be oriented parallel to vertical dimension Z of frame  26  (see, e.g.,  FIG. 7A ). Because the fibers of tape  60  run parallel to its length L, forming frame  26  in this way will ensure that the fibers of frame  26  run parallel to the inner and outer frame edges, even around the corners of frame  26 , as described in connection with  FIG. 8 . 
     Equipment for forming this type of fiber-based composite electronic device frame is illustrated in  FIG. 14 . 
     Initially, fiber tape such as prepreg tape  60  is provided to winding machine  80 . Machine  80  winds tape  60  around a form such as mandrel  62  of  FIG. 10 . 
     Curing tool  82  may apply heat and/or pressure (e.g., using a mold) until the prepreg has cured (i.e., until the binder has become mixed with the fiber and has set). In systems in which a non-curing thermoplastic material is used, tool  82  may be used to apply heat and/or pressure so as to melt and resolidify the thermoplastic material (rather than to curing prepreg formed of a thermoset material). If desired, winding machine  80  may include heaters (e.g., heating elements that are incorporated into rotating arms, rollers, or other winding mechanisms). In this type of system, the tape that is being wound onto the mandrel may be melted or cured right as it is being applied to the mandrel, using the heaters of the winding tool. 
     The workpiece that is supplied by tool  82  may be machined (if desired) using machining tool  84  (e.g., a tool such as tool  72  of  FIG. 12 , a laser cutting tool, or other machining equipment). 
     It may be desirable to add parts to the machined frame assembly that is supplied by tool  84 . Additional parts may be attached using adhesive, screws, mating features, or other suitable fastening techniques. The additional parts that are attached may be pre-machined or may be blank, unfinished materials. Additional parts may be formed from plastic, glass, ceramic, metal, composites, other materials, or combinations of these materials. As one example, bonding tool  86  may be used to adhesively bond a layer of unfinished aluminum (i.e., an elongated rod of aluminum or other metal blank with a rectangular cross section) to one of the edges of frame  26 . 
     This assembly may be machined using machining tool (e.g., a computer-controlled milling machine). 
     Illustrative steps involved in forming frame  26  using equipment of the type shown in  FIG. 14  are set forth in the flow chart of  FIG. 15 . 
     At step  90 , fiber tape  60  such as prepreg tape (e.g., tape with longitudinally oriented carbon fibers in a binder such as epoxy or other carbon tape) may be wound over mandrel  62 . 
     At step  92 , a curing tool (e.g., a tool with a heated mold such as tool  82 ) may cure the wound tape structure by applying heat and pressure. 
     The resulting structure may be machined at step  94  (e.g., by using tool  84  of  FIG. 14  to create grooves and a shelf as shown in frame  26  of  FIG. 13 ). 
     At step  98 , an aluminum blank or other suitable additional parts may be bonded to the machined frame structure (e.g., using adhesive and bonding tool  86  of  FIG. 14 ). 
     The aluminum blank or other additional structures may be machined and the profile of the fiber portion of frame  26  may be machined during the operations of step  100  (e.g., using machining tool  88  of  FIG. 14 ). 
     If desired, frame  26  may be formed using fiber-based structures that have joints with perpendicularly oriented fibers. This type of scenario is illustrated in the example of  FIGS. 16 and 17 . 
     As shown in  FIG. 16 , frame  26  may be formed (at least partly) from frame members  26 - 1  and  26 - 2 . Frame member  26 - 1  may have fibers that run parallel to longitudinal frame member axis  102 . Frame member  26 - 2  may have fibers that run parallel to longitudinal frame member axis  104 . A joint such as a lap joint or other suitable joint may be used to attach frame member  26 - 1  to frame member  26 - 2  (e.g., using adhesive  112 ). Frame member  26 - 1  may have notch  106  and frame member  26 - 2  may have notch  108  to facilitate forming a lap joint when members  26 - 1  and  26 - 2  are joined along dashed lines  110 . 
     After members  26 - 1  and  26 - 2  are attached to one another, an outer fiber-based layer may be created to complete frame  26  while providing frame  26  with additional strength. The corner at which frame members  26 - 1  and  26 - 2  meet may be eased by machining away portions  114  of  FIG. 16  (if desired). 
     After the assembly formed by members  26 - 1  and  26 - 2  has been processed (e.g., by curing and optional machining), carbon tape or other tape  60  may be wound around the machined assembly to form outer frame member  26 - 3 . As illustrated by dashed lines  116  in  FIG. 17 , the fiber in outer frame portion  26 - 3  will run parallel to the inner and outer edges of portion  26 - 3 , thereby enhancing the strength of frame  26  as described in connection with  FIG. 8 . 
     In the example of  FIGS. 16 and 17 , frame portions  26 - 1  and  26 - 2  have substantially rectangular cross-sectional shapes. If desired, pultrusion techniques, machining techniques, or other techniques may be used to form frame members such as members  26 - 1  and  26 - 2  that have a T-shaped cross section (or other desired cross sections). 
       FIG. 18  shows how frame material  122  may be pulled and extruded in direction  118  through pultrusion tool  120  (e.g., by pulling fiber through a reservoir of binder while applying heat). Once cut into desired lengths and machined, strips of frame material  122  may serve as frame members  26 - 1  and  26 - 2 . Other techniques may be used for forming elongated frame members if desired (e.g., using lamination and compression techniques. 
       FIG. 19  shows how fiber tape  60  of  FIG. 9  may be wound by winding tool  134  around a frame assembly formed from fiber-based frame members  26 - 1  and  26 - 2  to form a rectangular peripheral frame portion with longitudinally aligned fibers such as frame portion  26 - 3  of  FIG. 17 . A curing tool (e.g., a heated mold) may be used to co-cure frame members  26 - 1 ,  26 - 2 , and  26 - 3  to form frame  26 . If desired, optional additional parts (e.g., aluminum blanks) may be bonded to the frame and machined and/or additional frame machining may be performed before frame  26  is used as part of device housing  12  in device  10 . 
       FIG. 20  illustrates how T-shaped frame members  26 - 1  and  26 - 2  or frame members with other suitable cross-sectional shapes may be attached to each other using a lap joint arrangement of the type described in connection with  FIG. 16 . 
       FIG. 21  is a perspective cross-sectional view of an edge segment of frame  26  of  FIG. 19 . As shown in  FIG. 21 , frame  26  may include portions such as member  26 - 2  (formed by pultrusion or other suitable techniques) and wound tape layers such as layers  60  in portion  26 - 3 . 
     Equipment that may be used in forming frame  26  of  FIG. 21  (e.g., using a combination of pultrusion and winding techniques or other techniques) is shown in  FIG. 22 . 
     As shown in  FIG. 22 , composite material (e.g., carbon fiber and binder) may be formed into strips (e.g., T-sections or elongated structures with other suitable cross-sectional shapes) for members  26 - 1  and  26 - 2  using pultrusion tool  120  (or other suitable equipment). 
     Following optional curing operations, machining operations may be performed by machining tool  128  (e.g., to form notches such as notches  106  and  108  in frame members  26 - 1  and  26 - 2  as shown in  FIG. 20 ). 
     Bonding tool  130  may use adhesive and pressure to attach pultrusion frames member  26 - 1  and  26 - 2  together to form a four-sided frame assembly (e.g., using lap joints). 
     Machining tool  132  may perform optional machining operations to form features in the frame assembly (e.g., screw holes, recesses, eased corners and edges, ledges, etc.). 
     Winding tool  134  may be used to wind fiber tape  60  around the assembly formed from the four pultrusion frame members. 
     Tool  136  (e.g., a curing tool or other tool for applying heat and pressure such as a heated mold) may apply heat and pressure to the wound tape and the rest of the frame assembly. When thermoset materials are being processed, the application of heat and pressure may co-cure the tape layers and the frame members (e.g., pultrusion frame members) together to form a unitary cured frame assembly. When thermoplastic materials are being processed, the application of heat and pressure may melt the tape layers and frame members together. 
     Bonding tool  138  may be used to bond an aluminum blank or other optional additional parts to the frame assembly with adhesive. 
     Machining tool  140  may be used to machine features into the bonded aluminum blank or other additional material that was bonded to the frame assembly and/or to the frame assembly frame members formed from the fiber-based material. 
     Illustrative steps involved in forming a frame using the equipment of  FIG. 22  are shown in the flow chart of  FIG. 23 . 
     At step  142 , frame members  26 - 1  and  26 - 2  (sometimes referred to as T-sections because they may have a T-shaped cross sections) may be formed using pultrusion tool  120  or using other suitable frame member fabrication equipment. 
     At step  144 , lap joint structures such as notches  106  and  108  may be formed in frame members  26 - 1  and  26 - 2  using machining tool  128 . Other types of notches, grooves, and mating surfaces may be formed if desired. The use of lap joint notches in joining frame members together is merely illustrative. 
     At step  146 , bonding tool  130  may be used to bond frame members  26 - 1  to  26 - 2  (e.g., using adhesive at each lap joint such as adhesive  112  of  FIG. 17 ) 
     At step  148 , machining tool  132  (which may be the same tool as tool  128  or a different tool) may be used to machine eased corners and other features into the bonded frame assembly. 
     At step  150 , the frame assembly formed from members  26 - 1  and  26 - 2  may be held in place (e.g., inside a mold in a winding tool) and may be covered with wound layers of tape  60  using the winding tool (e.g., winding tool  134 ). The wound layers of tape  60  form frame portion  26 - 3 . 
     The frame assembly with its wound layers of outer tape may be heated (e.g., using the mold in the winding tool or other tool  136 ) during the operations of step  154 . The heating process may cure and/or melt the frame members so that the frame members and the hoop-shaped structure formed from the tape are joined together. 
     At step  156 , bonding tool  138  (which may be the same as bonding tool  130  or which may be a separate bonding tool) may be used to bond aluminum blank  160  ( FIG. 25 ) on frame  26 . 
     During the operations of step  158 , machining tool  140  (which may be the same or different than tools  128  and  132 ) may be used to machine desired features into aluminum blank  160  and/or the fiber-based portions of frame  26 , thereby forming a completed frame. The finished frame may be assembled with other portions of device  10  (e.g., internal components  28  and display  18 ) to form a finished device  10 . Screws and other fasteners and adhesive may be used in attaching frame  26  to other portions of device  10 . 
       FIG. 24  is a perspective view of an illustrative frame assembly before attachment of aluminum blank  160 . 
       FIG. 25  is a perspective view of the frame assembly of  FIG. 24  following attachment of blank  160 . 
       FIG. 26  shows a finished version of frame  26  following machining of blank  160  and frame members  26 - 1 ,  26 - 2 , and  26 - 3 . 
     If desired, frames may be formed by using adhesives or other attachment mechanisms to attach a complete or substantially complete fiber-composite hoop structure to a preassembled frame assembly. A process of this type is shown in the flow chart of  FIG. 27 . 
     During the operations of step  162  of  FIG. 27 , tape (e.g., tape  60  of  FIG. 10 ) may be wound into a rectangular ring shape or other suitable shape. For example, tape may be wound around a mandrel to form a hoop of fiber-based material (e.g., a rectangular ring). The wound tape may be cured (e.g., when the tape is formed from a thermoset material) or heated and pressed into shape (e.g., when the tape is formed from a thermoplastic material). The hoop-shaped frame structure that is formed from the wound tape may be used in forming an outer rectangular ring (hoop) for frame  26 . 
     Frame members may be formed during the operations of step  164 . Frame members may have any suitable cross sectional shape (e.g., rectangular shapes, T-shaped shapes, L-shaped shapes, shapes with non-parallel sidewalls, circular shapes, shapes with both curved and straight sides, etc.). If desired, the lengths of the frame members (i.e., the longitudinal dimensions of the frame members when measured along their longitudinal axes) may be larger (e.g., 3 or more times larger, 10 or more times larger, etc.) than their widths (i.e., the frame members may be formed as elongated members suitable for forming a rectangular frame assembly for supporting a display or other rectangular electronic device component. 
     Frame members may be formed from fiber-based composites (as an example). Pultrusion techniques and other techniques may be used in forming elongated frame members. For example, frame members  26  may be formed by lamination and compression molding techniques or other suitable techniques. The use of pultrusion techniques to form frame members in connection with frame  26  is merely illustrative. 
     The frame members that are produced at step  164  may be cured before further processing or may be maintained in an uncured state (e.g., for curing during subsequent frame assembly steps). For example, prepreg frame members with interlocking corners may be formed during the operations of step  164  that are suitable for attaching together. Frame members of this type may be cured together using a curing tool. 
     A frame assembly may be formed from the elongated frame members during the operations of step  166 . For example, four frame members may be assembled into a unitary rectangular ring structure by curing the frame members together in a common mold or by heating and compressing four frame members of a thermoplastic material together using a heated press. Frame members may also be assembled to form a frame assembly using screws or other fasteners, springs, clips, engagement structures of other shapes, notches, grooves, adhesive, other fastening structures, and using combinations of these approaches. Frame members may have notches for forming lap joints or may be joined using other types of joints such as T-joints, butt joints, corners joints, edge joints, etc. 
     If desired, frame  26  may be formed from four elongated members that are joined together, but that are not surrounded by an outer hoop structure. To enhance strength and resistance to unintended impact events, however, it is generally preferably to mount the frame assembly within an outer hoop structure. As shown in  FIG. 27 , for example, after forming a hoop-shaped frame structure such as an outer rectangular ring structure during the operations of step  162  and after forming a frame assembly such as an inner rectangular ring frame assembly during the operations of steps  164  and  166 , the hoop and frame assembly may be joined (step  168 ). For example, the rectangular frame assembly of step  166  may be mounted within the hoop of step  162  using adhesive, fasteners, or other suitable attachment mechanisms. Additional structures may be added if desired (e.g., by bonding metal blanks, by machining bonded metal blanks, etc.). 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20110316
Publication Date: 20141118
Grant Date: 20141118
Priority Date: 20100824
Inventors: DIFONZO JOHN C.
KENNEY KEVIN
GARELLI ADAM T.
LIGTENBERG CHRISTIAAN A.
Assignee: APPLE INC
CPC Classifications: [{"code": "B29C65/48", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C70/545", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/1222", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/721", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C53/562", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29K2307/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/1224", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/52431", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C70/865", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/43421", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C70/84", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29L2012/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/7422", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C70/52", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2031/3481", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/52431", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2031/3481", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C70/52", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C70/545", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/721", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C70/865", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/7422", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C70/84", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29C53/562", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29L2012/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29K2307/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/1224", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/1222", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/48", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/43421", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 45696216