PATENT DOCUMENT

Publication Number: US-10201105-B2
Application Number: US-201615140177-A
Country: US
Kind Code: B2

Title: Combination injection molding and hydroforming

Abstract:
Manufacturing methods that combine molding processes and shaping processes are described. The systems and methods described can be used to form composite parts using a single manufacturing process. In some embodiments, the methods involve positioning a workpiece within a mold cavity, then injecting a moldable material within the cavity at pressures sufficient to deform the workpiece such that features, such as protrusions or cavities, are formed within the workpiece. The resultant composite part includes the workpiece molded to a molded material. In some embodiments, the workpiece is a layer of metal material and the molded material is a structurally rigid plastic material, such that the composite part is a structurally rigid plastic with a metal coating. In some embodiments, multiple workpieces are molded within a composite part.

Claims:
What is claimed is: 
     
       1. A method of forming a composite part, the method comprising:
 positioning a workpiece within a mold cavity of a mold; 
 closing a valve within the mold cavity to at least partially define an enclosed portion of the mold cavity, the enclosed portion being less than an entirety of the mold cavity; 
 while the valve is closed, injecting a first amount of a moldable material into the enclosed portion of the mold cavity, thereby filling the enclosed portion and deforming a portion of the workpiece against a wall of the mold; 
 opening the valve; 
 while the valve is open, injecting a second amount of the moldable material into the mold cavity; and 
 hardening the first amount and the second amount of the moldable material, thereby bonding the moldable material to the workpiece. 
 
     
     
       2. The method of  claim 1 , further comprising, prior to the operation of injecting the first amount of the moldable material, preconditioning the workpiece such that the workpiece is more deformable. 
     
     
       3. The method of  claim 2 , wherein the preconditioning includes heating the workpiece or chemically treating the workpiece. 
     
     
       4. The method of  claim 1 , wherein the workpiece includes at least one of metal, a polymer material, glass, ceramic, or a composite material. 
     
     
       5. The method of  claim 1 , wherein the moldable material includes of one or more of metal, a polymer material, glass, ceramic, or a composite material. 
     
     
       6. The method of  claim 1 , wherein the workpiece includes a same material as the moldable material. 
     
     
       7. The method of  claim 1 , wherein the workpiece includes a different material than the moldable material. 
     
     
       8. The method of  claim 1 , wherein the mold wall includes a protruding feature. 
     
     
       9. The method of  claim 1 , further comprising, after the operation of injecting the second amount of the moldable material, removing at least a portion of the moldable material from the composite part. 
     
     
       10. The method of  claim 1 , wherein:
 the mold comprises multiple valves within the mold cavity; and 
 the enclosed portion of the mold cavity is further defined by the multiple valves when the multiple valves are in a closed state. 
 
     
     
       11. A method of forming a composite part, the method comprising:
 while a valve within a mold cavity is closed, injecting a polymer material at a first pressure into a first region of the mold cavity, the first region separated from a second region of the mold cavity by the valve, thereby deforming a workpiece within the mold cavity; 
 changing a position of the valve; and 
 after changing the position of the valve, injecting the polymer material at a second pressure, less than the first pressure, into the first region and the second region of the mold cavity. 
 
     
     
       12. The method of  claim 11 , wherein the polymer material bonds with the workpiece. 
     
     
       13. The method of  claim 11 , wherein the workpiece includes at least one of metal, a polymer material, glass, ceramic, or a composite material. 
     
     
       14. The method of  claim 11 , wherein:
 the mold cavity is a first mold cavity; and 
 the method further comprises:
 removing the composite part from the first mold cavity; 
 positioning the composite part within a second mold cavity, wherein the polymer material is a first polymer material; and 
 injecting a second polymer material into the second mold cavity such that the second polymer material bonds with the first polymer material. 
 
 
     
     
       15. The method of  claim 11 , further comprising: removing the composite part from the mold cavity; and performing a machining operation or a surface finishing operation on the composite part. 
     
     
       16. The method of  claim 11 , wherein the composite part is an enclosure for an electronic device, wherein the workpiece corresponds to a cosmetic exterior coating of the enclosure. 
     
     
       17. A method of forming a composite part, comprising:
 positioning a workpiece within a mold cavity of a mold, the workpiece comprising a gate feature projecting into the mold cavity and separating the mold cavity into a first molding region and a second molding region; 
 injecting a first amount of a polymer at a first pressure into the mold cavity, thereby:
 molding a region of the workpiece within the first molding region against a feature of the mold; and 
 bending the gate feature to join the first molding region and the second molding region; and 
 
 injecting a second amount of the polymer at a second pressure, less than the first pressure, into the mold cavity. 
 
     
     
       18. The method of  claim 17 , wherein the workpiece is formed of a metal. 
     
     
       19. The method of  claim 17 , wherein the gate feature is integrally formed with the workpiece. 
     
     
       20. The method of  claim 17 , wherein the gate feature is fastened to the workpiece.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority under 35 U.S.C § 119(e) to U.S. Provisional Application No. 62/183,129, entitled “COMBINATION INJECTION MOLDING AND HYDROFORMING,” filed on Jun. 22, 2015, and to U.S. Provisional Application No. 62/202,672, entitled “COMBINATION INJECTION MOLDING AND HYDROFORMING,” filed on Aug. 7, 2015, each of which is incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This disclosure relates generally to injection molding systems and methods. In particular, injection molding systems and methods that involve intentional deformation of a workpiece, similar to hydroforming techniques, are described. 
     BACKGROUND 
     Injection molding is a process that involves injecting a moldable material, such as thermoformable resin, into a mold under pressure such that a resultant part has a shape conforming to a mold cavity of the mold. After the moldable material cools and solidifies, the part is removed from the mold. 
     Hydroforming is a process whereby a pressurized hydraulic fluid is applied to a ductile material such as some metals to shape the material. Hydroforming is typically used to shape tubing and other large structures. After the forming process is complete, the hydraulic fluid is removed from the shaped part. Combining aspects of injection molding and hydroforming techniques can improve manufacturing efficiency and cost of some product lines. 
     SUMMARY 
     This paper describes various embodiments that relate to manufacturing methods that combine molding processes and shaping processes. The systems and methods described can be used to form composite parts using a single manufacturing process. 
     According to one embodiment, a method of forming a composite part is described. The method includes positioning a workpiece within a mold cavity of a mold. The method also includes injecting a moldable material within the mold cavity such that an applied pressure exerted on the workpiece by the moldable material deforms the workpiece to take on a predetermined shape. The moldable material bonds with the workpiece to form the composite part. 
     According to another embodiment, a method of forming a composite part is described. The method includes injecting a polymer material into a mold cavity of a mold such that a flow of polymer material is directed toward a surface of a workpiece positioned within the mold cavity. An applied pressure associated with the flow deforms the workpiece to create a protruding feature on the workpiece corresponding to a recessed feature of the mold. 
     According to a further embodiment, an enclosure for an electronic device is described. The enclosure includes a polymer base that includes a protruding feature integral to the polymer base. The enclosure also includes a cosmetic coating that covers at least a portion of a surface of the polymer base, wherein the cosmetic coating continuously covers the protruding feature. 
     According to an additional embodiment, an enclosure for an electronic device is described. The enclosure includes an exterior layer having a recessed feature. The enclosure also includes a polymer base bonded to the exterior layer. The polymer base has a protruding feature, wherein the recessed feature surrounds the protruding feature of the polymer base. 
     These and other embodiments will be described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements. 
         FIGS. 1A-1D  show cross-section views of a composite part being formed using a molding process in accordance with some described embodiments. 
         FIGS. 2A-2B  show cross-section views of a composite part having multiple workpieces being formed using a molding process in accordance with some described embodiments. 
         FIGS. 3A-3D  show cross-section views of a composite part having multiple molded materials being formed using a molding process in accordance with some described embodiments. 
         FIGS. 4A-4D  show cross-section views of another composite part having multiple workpieces and molded parts being formed using a molding process in accordance with some described embodiments. 
         FIG. 5  shows a flowchart that indicates a process for forming composite part using a molding process in accordance with described embodiments. 
         FIGS. 6A-6B  show cross-section views of a composite part having an insert being formed using a molding process in accordance with some described embodiments. 
         FIGS. 7A-7D  show cross-section views of a composite part having antenna elements being formed using a molding process in accordance with some described embodiments. 
         FIGS. 8A-8B  show cross-section views of a composite part having mechanical interlocks being formed using a molding process in accordance with some described embodiments. 
         FIGS. 9A-9B  show cross-section views of a composite part having micro-pore interlocks being formed using a molding process in accordance with some described embodiments. 
         FIGS. 10A-10B  show cross-section views of a composite part having functional features being formed using a molding process in accordance with some described embodiments. 
         FIGS. 11A-11B  show cross-section views of a composite part formed using a molding process using a mold with segregation features, in accordance with some described embodiments. 
         FIGS. 12A-12B  show cross-section views of a composite part formed using a molding process using a mold with shutoff valves, in accordance with some described embodiments. 
         FIGS. 13A-13B  show cross-section views of a composite part formed using a molding process using a mold with sacrificial relief valves, in accordance with some described embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, they are intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Described herein are manufacturing processes that involve coupling a moldable material with a workpiece while simultaneously changing a shape of the workpiece. Methods involve injecting the moldable material within a mold such that a flow of the moldable material is directed at a surface of the workpiece and at an applied pressure sufficiently high to deform the workpiece to a predetermined shape. The methods can involve deforming the workpiece in a controlled manner to reduce the formation of cosmetic defects within the workpiece. 
     One of the advantages of the methods described herein over conventional injection molding processes is that a shape of the workpiece is intentionally changed during the injection molding process. Thus, injection molding and shaping can be accomplished in a single manufacturing process. One of the differences of the some of the procedures described herein and hydroforming processes is that hydroforming fluid does not remain bonded to a workpiece. That is, the hydraulic fluid used in hydroforming is only used as a medium to apply pressure and deform a metal material. In contrast, the moldable material in embodiments described herein is applied at pressures sufficient to deform a workpiece, and also becomes bonded with the workpiece as part of the final composite part. 
     It should be noted that the methods described herein differ from insert molding techniques. Insert molding involves molding plastic material around an insert such the insert become integrated within the part. In insert molding, care is taken to assure that the molding process does not deform the insert. Unlike insert molding, the embodiments described herein involve intentionally deforming a workpiece by the molding process. In particular, embodiments, the workpiece is deformed in a manner such that the workpiece takes on a predetermined shape. 
     Methods described herein are well suited for manufacture of consumer products. For example, the methods described herein can be used to form housings or components for computers, portable electronic devices, wearable electronic devices, and electronic device accessories, such as those manufactured by Apple Inc., based in Cupertino, Calif. 
     These and other embodiments are discussed below with reference to  FIGS. 1A-13B . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIGS. 1A-1D  show cross-section views of a composite part being formed using a molding process in accordance with some described embodiments.  FIG. 1A  shows a portion of mold  100 , which includes first mold portion  100   a  and second mold portion  100   b , prior to an injection molding process. First mold portion  100   a  and second mold portion  100   b  together form mold cavity  104  wherein a moldable material is injected. Mold cavity  104  is defined by cavity walls  106 . First mold portion  100   a  includes opening  108  that acts as an inlet into mold cavity  104  for a moldable material. Second mold portion  100   b  includes mold feature  110  that corresponds to a recess within second mold portion  100   b.    
     Prior to the injection molding process, workpiece  102  is positioned within mold cavity  104 . Workpiece  102  can be positioned relative to mold feature  110  such that pressure from injecting a moldable material can causes deformation of workpiece  102  into mold feature  110 . In some embodiments, the position of workpiece  102  is secured relative to first mold portion  100   a  and/or second mold portion  100   b  to prevent movement of workpiece  102  during a subsequent injection molding process. For example, portions of first mold portion  100   a  and second mold portion  100   b  (not shown) can clamp down on and secure workpiece  102 . Alternatively or additionally, workpiece  102  can be secured to portions of first mold portion  100   a  and/or second mold portion  100   b  using an adhesive (not shown). 
     Workpiece  102  can be made of any suitable material that is deformable during a subsequent molding process. In some embodiments, workpiece  102  is made of one or more of metal, polymer material, glass, ceramic, and composite materials (e.g., fiberglass). In a particular embodiment, workpiece  102  is made of an aluminum or aluminum alloy. The thickness T of workpiece  102  can vary depending on a number of factors such as the material of workpiece  102  and an amount of pressure that will be applied to workpiece  102  during the subsequent molding process. For example, workpiece  102  that is made of brittle material, such glass and ceramic, may be required to be very thin in order to deform without fracturing. In a particular embodiment, workpiece  102  includes a very thin layer (e.g., 10 to 30 micrometers) of zirconia or other ceramic material, which can be sufficiently deformed without cracking due to its thinness. In some embodiments, workpiece  102  is a metal material that has a thickness T on the scale of millimeters or more. 
     It should be noted that workpiece  102  can have any suitable shape and is not limited to the substantially flat shape shown in  FIGS. 1A-1D . For example, instead of a substantially flat sheet of material, workpiece  102  can have a spherical, oblong, or block shape. In some embodiments, workpiece  102  has a uniform thickness, such as shown in  FIGS. 1A-1D , while in other embodiments workpiece  102  has a varied thickness. 
     In some embodiments, workpiece  102  undergoes one or more preconditioning processes prior to the molding process that can make workpiece  102  more deformable. In some embodiments, the preconditioning process involves heating workpiece  102 . For example, brittle materials such as glass and ceramic can be heated to a temperature sufficient to put the glass or ceramic in a moldable and flexible state. Metals and polymer materials can also be heated to make them more moldable. Workpiece  102  is placed within mold cavity  104  while in the moldable state such that when a moldable material is injected into mold cavity  104  and applied pressure to workpiece  102 , workpiece  102  conforms to walls  106  of mold  100  without breaking or cracking. In some embodiments, the one or more of first mold portion  100   a  and second mold portion  100   b  are configured to heat workpiece  102  while within mold cavity  104 . In addition to making workpiece  102  more deformable, heating workpiece  102  may make a subsequently molded moldable material bond more effectively with workpiece  102 . 
     Another type of preconditioning process can include chemical treatment, such as a chemical etching process. In a particular embodiment, surface  102   a  of workpiece  102  is etched to form an irregular or porous textured surface that can form a more effective bond with a subsequently molded-on moldable material. 
       FIG. 1B  shows mold  100  during an injection molding process where moldable material  112  is injected into opening  108  and into mold cavity  104 . Moldable material  112  is injected within mold cavity  104  at a pressure P sufficient to couple and bind moldable material  112  to workpiece  102 . A flow of moldable material  112  is directed toward surface  102   a  of workpiece  102 , and an applied pressure P associated with the flow of moldable material  112  is sufficiently high to deform workpiece  102 . In particular, the shape of workpiece  102  changes from a substantially flat shape prior to injection molding to a shape in conformance with second mold portion  100   b  including mold feature  110 . That is, a portion of workpiece  102  is forced into mold feature  110  and takes on a shape in accordance with mold feature  110 . In this way, workpiece  102  can take on a predetermined shape defined by mold feature  110 . 
     Moldable material  112  can be made of any suitable material that can be in a flowable state during the molding process. In some embodiments, moldable material  112  is made of one or more of polymer material (e.g., thermoformable resin), metal, glass, ceramic, and composite material. Moldable material  112  should also be made of a material that can bond with workpiece  102  during the injection molding process. Thus, the material of moldable material  112  may depend, in part, on the material of workpiece  102 . In particular embodiments, moldable material  112  is made of a polymer material and workpiece  102  is made of a metal material (e.g., aluminum or aluminum alloy). 
     The pressure P at which moldable material  112  is injected into and applied onto workpiece  102  can vary depending, in part, on the material and thickness T of workpiece  102 . The applied pressure P should be sufficiently high to deform workpiece  102  to take on a shape corresponding to the shape of second mold portion  100   b . However, too high of pressure P can cause workpiece  102  to tear or create defects within workpiece  102 . Thus, the thickness and material strength of workpiece  102  should be taken into consideration. In some cases where workpiece  102  is made of metal, too high of pressures used during the molding process can cause grain elongation of the metal material, which can negatively affect the cosmetic appearance of workpiece  102 . For example, workpiece  102  may take on a wavy or rippled appearance. Thus, the applied pressure P can be tuned to achieve sufficient deformation while preventing or mitigating structural or cosmetic defects within workpiece  102 . 
     In some embodiments, a computer simulation program, such as a viscous burst test, may be used to model the formability of workpiece  102  to a desired cavity shape of mold cavity  104 . The computer simulation can evaluate variables such as the thickness T of workpiece  102 , the shape of mold cavity  104 , the pressure of the moldable material, and the temperature of the mold process. The computer simulation can be used to predict an optimal flow rate and pressure of the moldable material during the forming process to reduce cosmetic surface imperfections such as grain elongation as well as prevent defects from forming in workpiece  102 . 
     In some embodiments, the pressure P at which moldable material  112  is applied onto workpiece  102  is done in stepwise manner. For example, initial pressures and speed at which moldable material  112  flows into mold cavity  104  can be relatively low such that workpiece  102  can be allowed to mold into and conform to the shape of mold feature  110  without breaking or tearing. Once workpiece  102  is molded within and substantially in conformance with mold feature  110 , the pressure P and speed of flow of moldable material  112  can be increased to densely compact moldable material  112  within mold cavity  104  and against workpiece  102 . 
     Note that since the molding process can involve high pressures, the molding process in itself can create thermal energy that heats workpiece  102  and makes workpiece  102  more deformable compared to room temperature conditions. Thus, in some embodiments, the molding process can add sufficient heat to workpiece  102  to provide good deformation and bonding capability to workpiece  102  such that a preconditioning heating process is not necessary. However, in some embodiments, the thermal energy from the injection molding is not sufficient to heat workpiece  102  to a sufficient temperature for deformation without cracking or breaking workpiece  102 . In these cases, the preconditioning heating process can be used to preheat workpiece  102  prior to injection molding. For example, workpiece  102  made of some metal materials may be sufficiently heated during the molding process such that a preconditioning heating process is not needed. However, workpiece  102  made of some glass or ceramic materials may need the preconditioning heating process so that workpiece  102  adequately deforms without cracking. After the injection molding process is complete, moldable material  112  is allowed to cool and harden forming a hardened molded material that is bonded to the workpiece. 
       FIG. 1C  shows composite part  114  after removal from mold  100 . Composite part  114  includes feature  115  that has a shape corresponding to the shape of mold feature  110 . In particular, feature  115  is a protruding feature that matches the recessed mold feature  110 . In other embodiments, recessed features can be formed within composite part  114  by using a mold with a corresponding protruding feature in a similar manner. As shown, in some embodiments, composite part  114  includes vestige  116  remaining on molded material  112  where moldable material  112  entered mold cavity  104 . 
       FIG. 1D  shows composite part  114  after vestige  116  is removed using one or more machining and/or surface finishing operations (e.g., sanding, polishing or buffing) forming a finished surface  112   a . Additionally or alternatively, composite part  114  can undergo a machining operation to provide a final shape to composite part  114  or to form more features (e.g., holes, indentations, etc.) in composite part  114 . In some embodiments, workpiece  102  of composite part  114  undergoes a post-molding finishing operation to remove cosmetic inconsistencies caused by the shaping and molding process, such as grain elongation and other cosmetic defect described above. For example, a sanding, polishing and/or buffing operation can be used to smooth out any waviness or rippled appearance as an artifact of the pressurized shaping process. 
     In some embodiments, composite part  114  is an enclosure, or part of enclosure, for an electronic device. For example, exposed surface  102   b  of workpiece  102  can correspond to an exterior surface of the enclosure, with surface  112   a  of molded material  112  corresponding to an interior surface of the enclosure that supports internal components of the electronic device and is hidden from view from a user. In a particular embodiment, workpiece  102  corresponds to a layer of metal material that covers an entire surface, or a portion of a surface, of molded material  112  such that workpiece  102  serves as a cosmetic covering to composite part  114 . Molded material  112  can be a structural portion of the enclosure that provides strength and structural integrity to the enclosure. 
     As described above, one of the advantages the molding processes described herein over conventional injection molding processes is that workpiece  102  can be shaped and molded and material  112  can be coupled to workpiece  102  in one manufacturing process. This is in contrast to conventional processes where workpiece  102  would be shaped in a first manufacturing process, such as a stamping or hydroforming process, and then coupled to molded material  112  in a second manufacturing process, such as an injection molding process. Thus, combining these processes into one manufacturing process, as described herein, saves costs related to manufacturing time and cycle time. In addition, the first and second manufacturing processes would require different tools, e.g., a stamping or hydroforming tool and an injection molding tool. Hence, combining these processes into a single process using one tool can save costs related to additional equipment. 
     An advantage of the molding processes described herein over conventional machining processes where feature  115  is machined within part  114  is that such machining processes would result in a large amount of material waste. That is, areas of workpiece  102  surrounding feature  115  would have to be machined away and discarded. In contrast, the methods described herein can mainly involve material manipulation rather than bulk material removal, resulting in large cost savings related to material waste. 
     It should be noted that the volume of feature  115 , indicated in  FIG. 1D  by distance D that feature protrudes from composite part  114 , includes both the material of workpiece  102  and molded material  112 . This can provide an advantage over situations where the entire volume of feature  115  is only made of workpiece  102 . For example, if molded material  112  is made of a material that is more rigid and has more structural strength than the material of workpiece  102 , having a portion feature  115  made of molded material can add rigidity and structural strength to feature  115 . This can make feature  115  more robust and less easily deformed during the use of composite part  114 . For example, in embodiments where composite part  114  is a portion of a housing or enclosure of a portable electronic device, feature  115  would be less likely to be deformed from a drop event. 
     In some embodiments, the methods described herein are used to mold multiple workpieces together, where one or more of the workpieces are intentionally deformed during the injection molding process.  FIGS. 2A-2B  show cross-section views of composite part  200  having multiple workpieces  202  and  204  being formed using the methods described herein.  FIG. 2A  shows first workpiece  202  and second workpiece  204  positioned within mold cavity  104  of mold  100 . First workpiece  202  and second workpiece  204  can correspond to sheets of material that are stacked together in a laminar form. In some embodiments, an adhesive positioned between first workpiece  202  and second workpiece  204  to adhere first workpiece  202  with second workpiece  204  together. First workpiece  202  and second workpiece  204  can each be made of any suitable material, and can be made of the same material or different materials. 
     At  FIG. 2B , moldable material  206  is injected into mold cavity  104  such that injection pressure P of moldable material  206  is applied onto first workpiece  202  and second workpiece  204  such that first workpiece  202  and second workpiece  204  conform to a shape of second mold portion  100   b , including mold feature  110 . After the injection molding process is complete and moldable material  206  is hardened, composite part  200  can be removed from mold  100 . In some embodiments, second workpiece  204  is made of a cosmetically appealing material and will correspond to a visible portion of composite part  200 , with first workpiece  202  made of a more structurally rigid material and cosmetics being of lesser importance since first workpiece  202  can be hidden from view by second workpiece  204  on one side and moldable material  206  on another side. In a particular embodiment, second workpiece  204  is made of an aluminum alloy and first workpiece  202  is made of a stainless steel. 
     Note that in some embodiments, instead of a laminar configuration where first workpiece  202  and second workpiece  204  are both deformed during the injection molding process, the multiple workpieces includes an insert-molded piece that is not substantially deformed during the injection molding process. 
       FIGS. 3A-3D  show cross-sections views of a composite part being formed using multiple molding operations, in accordance with some embodiments.  FIG. 3A  shows a cross-section view of first mold  100  with workpiece  302  positioned within mold cavity  104 . At  FIG. 3B , first moldable material  304  is molded within mold cavity  104  at a prescribed pressure P such that workpiece  302  conforms to second mold portion  100   b , including within mold feature  110 . After first moldable material  304  is cooled and hardened and sufficiently bonded to workpiece  302 , molded material  304  and workpiece  302  are removed from mold  100 . In some embodiments, first molded material  304  and workpiece  302  are then subjected to one or more shaping processes (not shown), such as a machining and/or surface finishing operations. 
       FIG. 3C  shows first molded material  304  and workpiece  302  placed into second mold  310 , which includes first mold portion  310   a  and second mold portion  310   b , which define a second mold cavity  312 . First mold portion  310   a  has opening  308 , which is configured to accept a second moldable material during an injection molding process. Second mold portion  310   b  includes mold feature  311  that is shaped to accept shaped workpiece  302 . 
       FIG. 3D  shows second moldable material  306  injected into second mold cavity  312 , thereby forming composite part  300 . As shown, first moldable material  304  become sandwiched between second moldable material  306  and workpiece  302 . In some embodiments, first moldable material  304  is made of the same material as second moldable material  306 . In other embodiments, first moldable material  304  is made of a different material than second moldable material  306 . In some embodiments, first moldable material  304  is made of a more rigid material than second moldable material  306 , and second moldable material  306  is made of a more cosmetically appealing material than first moldable material  304 . After second moldable material  306  is sufficiently hardened, composite part  300  is removed from second mold  310 . 
       FIGS. 4A-4D  show cross-section views of a composite part having multiple molded materials and multiple workpieces being formed using methods described herein.  FIG. 4A  shows first mold  100  with first workpiece  402  being deformed during an injection molding process where first moldable material  404  is molded onto first workpiece  402  at a prescribed pressure P. During the molding process, first workpiece  402  is deformed so as to conform to the shape of mold feature  110 . After first moldable material  404  is cooled and hardened, first moldable material  404  and first workpiece  402  are removed from first mold  100 . 
       FIG. 4B  shows first molded material  404  and first workpiece  402  positioned within second mold  410 , which includes first mold portion  410   a  and second mold portion  410   b . First mold portion  410   a  includes opening  407  as an inlet for a second moldable material. Second mold portion  410   b  includes mold feature  412 , which is configured to accommodate the shape of first workpiece  402 . First mold portion  410   a  and second mold portion  410   b  define second mold cavity  405 . Second workpiece  406  is positioned second mold cavity  405  adjacent to first molded material  404 . 
       FIG. 4C  shows second moldable material  408  injected into second mold cavity  405 , thereby forming composite part  400 . As shown, first molded material  404  and second workpiece  406  become sandwiched between second moldable material  408  and first workpiece  402 . In some embodiments, each of first workpiece  402 , first molded material  404 , second workpiece  406 , and second moldable material  408  are made of different materials that attribute different structural or cosmetic qualities to composite part  400 . For example, first molded material  404  and second workpiece  406  can provide structural support for composite part  400 , while workpiece  402  and second moldable material  408  provide cosmetic attributes to composite part  400 .  FIG. 4C  shows composite part  400  after removal from second mold  410 . Composite part  400  can optionally undergo one or more post-molding machining and/or surface finishing processes. 
     It should be noted that composite structures and methods described herein are not limited to those described above with reference to  FIGS. 1A-4C , and that variations of these can fall within the scope of the inventions described herein. In addition, any suitable combination of the composite structures and methods described above with reference to  FIGS. 1A-4C  can be used. 
       FIG. 5  shows flowchart  500  indicating a process for forming a composite part in accordance with some described embodiments. At  502 , a preconditioning operation is optionally performed on a workpiece. The preconditioning can include one or more processes that make the workpiece more moldable and flexible for shaping during a subsequent molding operation. Additionally or alternatively, the preconditioning includes one or more processes that improve bonding with a subsequently molded-on moldable material. Suitable preconditioning operations can include heating the workpiece and/or exposing the workpiece to a surface etching process (e.g., chemical or laser etching). 
     At  504 , the workpiece is positioned in a mold. In some embodiments, two or more workpieces are placed within the mold. The mold includes walls that define a shape of the composite part. The workpiece can be positioned proximate to a mold feature, such as a recess or protrusion of the mold, so that the workpiece will deform in accordance with a shape of the mold feature. The mold can be designed to secure the workpiece during a subsequent injection molding process. 
     At  506 , a moldable material is injected within the mold so as to deform the workpiece and bond with the workpiece, thereby forming the composite part. In this way, the molding process accomplished two manufacturing tasks in one manufacturing operation: shaping the workpiece and bonding the moldable material with a moldable material. If two or more workpieces are used, the two or more workpieces are coupled together by the moldable material. Materials of each of the moldable material and the workpiece can be chosen based on desired cosmetic and/or structural qualities. In some embodiments, the workpiece is metal (e.g., aluminum alloy) and is chosen based on cosmetic appearance and durability, while the moldable material is a polymer material chosen based on structural soundness and rigidity. After the moldable material is hardened, the composite part can be removed from the mold. 
     At  508 , a post-molding process is optionally performed on the composite part. The post-molding process can include one or more shaping operations to create a final shape of the composite part. For example, surfaces of the composite part can be machined and/or finished to remove molding vestiges, grain irregularities, and other cosmetic defects from the molding process. In some embodiments, features such as holes and designs are formed on the composite part. 
     At  510 , another injection molding process is optionally performed on the composite part. The additional molding process can include molding on a second moldable material onto the composite part. In some embodiments, a second workpiece is also incorporated into the composite part during the second molding operation. 
       FIGS. 6A and 6B  show cross-section views of formation of a composite part using methods described above with insert molding.  FIG. 6A  shows mold  600  with workpiece  602  positioned therein prior to the molding process. Workpiece  602  has features  614  and  616  that can be positioned on surface  602   a  of workpiece  602  or partially within workpiece  602 . Features  614  and  616  can be located in an area between first mold portion  600   a  and second mold portion  600   b . In some cases, features  614  and  616  are situated where workpiece  602  is deformed during the molding process in conformance with mold feature  610 , which is defined by cavity walls  606 . 
     Features  614  and  616  can be made of any suitable material depending on a desired function of features  614  and  616 . In some embodiments, features  614  and  616  are made of one or more of metal, polymer material, glass, ceramic, and composite materials (e.g., fiberglass). Features  614  and  616  can be part of workpiece  602 , or features  614  and  616  can be additional components positioned on surface  602   a  of workpiece  602  prior to the molding process. In some embodiments, features  614  and  616  are formed from workpiece  602  through any suitable method, such as machining of workpiece  602 . In further embodiments, features  614  and  616  are secured to surface  602   a  of workpiece  602 , for example, using one or more of adhesive, welding, form fitting, and threaded coupling. In some embodiments, features  614  and  616  are designed to fasten separate components together during the molding process. For example, features  614  and  616  can be housing chassis components, brackets, nuts, and other features designed to fasten components together. 
       FIG. 6B  shows mold  600  during an injection molding process where moldable material  612  is injected through opening  608  against workpiece surface  602   a . As a result, features  614  and  616  are over-molded by moldable material  612 , and insert molded within moldable material  612 . Features  614  and  616  are displaced with workpiece surface  602   a  as workpiece  602  is deformed to conform to mold cavity  604 . Moldable material  612  bonds to workpiece  602  and features  614  and  616  forming a composite part. Features  614  and  616  can increase a bond strength between moldable material  612  and workpiece  602  by increasing the surface area over which moldable material  612  bonds. 
     In some embodiments, features  614  and  616  are exposed through one or more processes subsequent to the molding process, allowing for access to features  614  and  616 . For example, holes can be formed through moldable material  612  to features  614  and  616  using a machining operation. In embodiments where the composite part is a housing for an electronic device, access to features  614  and  616  may allow for fastening to other housing components or functional elements of the electronic device. 
       FIGS. 7A-7D  show cross-section views of formation of a composite part having antenna elements.  FIG. 7A  shows mold  700  having antenna features  714  and  716  separated with respect to each other by separation distance “S” before molding. S can be chosen to allow optimal performance of antenna features  714  and  716  in the final composite part. In some embodiments antenna features  714  and  716  are within an area defined by mold feature  710 . In some embodiments, workpiece  702  is made of a metal material than can functionally cooperate with antenna features  714  and  716 . In other embodiments, workpiece  702  is made of a radio frequency (RF) transparent material such as plastic, glass or ceramic. 
     At  FIG. 7B , moldable material  712  is molded onto workpiece  702  and antenna features  714  and  716 . During the molding process, moldable material  712  is injected into mold cavity  704  through opening  708 . Moldable material  712  can be made of an RF transparent material to allow radio access to antenna features  714  and  716  contained within moldable material  712 . Relative positioning of antenna feature  714  to antenna feature  716  (separation distance S) can remain constant during the molding process. In some embodiments, the pressure P at which moldable material  712  is applied to workpiece  702  is varied such that deformation of workpiece  702  is minimized during the molding process in order to assure S remains constant. For example, a first lower pressure can be applied to displace the workpiece  702  against mold cavity walls  706 , minimally deforming workpiece  702  as it conforms to mold feature  710 , then a higher pressure can be applied. By controlling the pressure and rate of deformation, relative positioning of features  614  and  616  can be maintained during the mold process. 
     In other embodiments, the molding process changes the separation distance S of antenna features  714  and  716  from a pre-molding separation distance to a post-molding separation distance. A pre-molding process separation distance S between antenna features  714  and  716  can be chosen such that the molding process positions antenna features  714  and  716  into a desired post-molding separation distance. The post-molding separation distance may be greater than or less than a pre-molding separation distance. 
       FIG. 7C  shows composite part  718  after removal from mold  700  with antenna features  714  and  716  embedded therein. Composite part  718  includes feature  715  that has a shape corresponding to the shape of mold feature  710 . In some embodiments, some of moldable material  712  is removed from composite part  718  to expose antenna features  714  and  716  as shown in  FIG. 7D . This can be accomplished using any suitable technique, including one or more machining operations. In some embodiments, portions of antenna features  714  and  716  and/or workpiece  702  are also removed. Remaining molding material  712   a  can define cavity  713  that exposes remnant antenna features  714   a  and  716   a  of antenna features  714  and  716 . In this way, remnant antenna features  714   a  and  716   a  can be formed within composite part  718  a predefined separation distance S from each other. 
       FIGS. 8A and 8B  show cross-section views of formation of a composite part using mechanical interlocks. At  FIG. 8A  workpiece  802  is positioned within mold  800 . Workpiece  802  is preconditioned to form mechanical interlocks  814  on surface  802   a  of workpiece  802 . Mechanical interlocks  814  can increase the surface area of surface  802   a , thereby increasing a bond between a subsequent applied moldable material to workpiece  802 . In some embodiments, mechanical interlocks  814  have dimensions on the scale of millimeters. Mechanical interlocks  814  can be formed using any suitable method for shaping surface  802   a , such as machining or etching (e.g., chemical or laser etching). In some embodiments mechanical interlocks  814  are in the form of grooves or pits. In some cases, mechanical interlocks  814  have undercut geometries (as shown) to enhance the bonding between workpiece  802  and the subsequently molded-on moldable material. In particular, mechanical interlocks  814  can have a smaller opening at surface  802   a  than within mechanical interlocks  814 . 
       FIG. 8B  shows moldable material  812  injected through opening  808  of first mold portion  800   a  and into mold cavity  804 . Pressure P exerted on moldable material deforms workpiece  802  such that workpiece  802  conforms to second mold portion  800   b , including within mold feature  810 . Pressure P should be sufficiently high and/or moldable material  812  should have sufficiently low viscosity such that moldable material  812  at least partially flows within mechanical interlocks  814 . In some cases, moldable material  812  is substantially fully molded within mechanical interlocks  814 . If mechanical interlocks  814  have undercut geometries, moldable material  812  engages with internal surfaces of mechanical interlocks  814 , further securing moldable material  812  to workpiece  802 . Once hardened, molded material  812  is permanently bonded to the workpiece  802  since separation may be destructive to moldable material  812  or workpiece  802 . 
     In further embodiments, the mechanical interlocks are on the scale of nanometers as shown in  FIGS. 9A and 9B .  FIG. 9A  shows workpiece  902  having micro-pore interlocks  914  positioned between first mold portion  900   a  and second mold portion  900   b  of mold  900  prior to injection molding. Micro-pore interlocks  914  can be formed using, for example, chemical or laser etching, mechanical techniques (e.g., pitting or blasting), and/or thermal processes. These methods can be used to form micro-pore interlocks  914  having engagement features (divots and protrusions) on the scale of nanometers. Micro-pore interlocks  914  can have irregular shapes caused by the micro-pore interlocks  914  forming process. In some cases, the irregular shapes of the micro-pore interlocks  914  can further strengthen the bond between workpiece  902  and moldable material  912 . 
     During the molding process, at  FIG. 9B , moldable material  912  is injected through opening  908  into mold cavity  904  at prescribed pressure P. Moldable material  912  is injected at a sufficient pressure to deform workpiece  902  such that workpiece  902  conforms to cavity walls  906  and mold feature  910 . Moldable material  912  flows into micro-pores interlocks  914 , bonding to the increased surface area of surface  902   a  of workpiece  902 . The viscosity of moldable material  912  should be sufficiently low and/or pressure P should be sufficiently high such that moldable material  912  at least partially flows within micro-pores interlocks  914 . Controlling a heating of moldable material  912  can further control the viscosity of moldable material  912 . 
       FIGS. 10A and 10B  show composite part  1000  includes functional features, in accordance with some embodiments. Composite part  1000  includes moldable material  1012  and workpiece  1002  having feature  1015  formed thereon using one or more of the molding processes described above. At  FIG. 10B , functional feature  1014  is formed from within surface  1012   a  of moldable material  1012  using, for example, a machining process. In some embodiments, functional feature  1014  is formed within an area of moldable material  1012  defined by feature  1015 . That is, functional feature  1014  can have a shape roughly corresponding to a shape of feature  1015 , as shown in  FIG. 10B . Functional feature  1014  can include various facets  1016 , which can have certain functional purposes for composite part  1000 . For example, facets  1016  can mate with or otherwise engage with a corresponding part. In some embodiments, composite part  1000  is a device housing and functional feature  1014  can be used to couple composite part  1000  to other housing components or internal device components. Feature  1015  can increases the thickness of composite part  1000  allowing for a larger functional feature  1014  to be formed in moldable material  1012 . 
     In some embodiments, the molding process includes methods to segregate the deformation of the workpiece into different areas.  FIGS. 11A and 11B  show mold  1100  having segregation features  1114  that define an area of workpiece  1102  affected by the molding process. At  FIG. 11A , workpiece  1102  is situated between first mold portion  1100   a  and second mold portion  1100   b  of mold  1100 . First mold portion  1100   a  has segregation features  1114  that contact surface  1102   a  of workpiece  1102  during the molding process forming “Shut offs” as shown in  FIG. 11A . In some embodiments, segregation features  1114  function as locators, interacting with features in workpiece  1102  to locate workpiece  1102  within mold  1100 . 
     At  FIG. 11B , moldable material  1112  is injected at pressure P into opening  1108  defined by workpiece  1102  and first mold portion  1100   a , which includes segregation features  1114 . Moldable material  1112  is restrained within cavity  1104  by segregation features  1114  and exerts pressure P only on a portion of workpiece  1102  within cavity  1104 . This portion of workpiece  1102  can be referred to as a mold-formed zone. Restricting the flow of moldable material  1112  allows for a reduction in pressure exerted on workpiece  1102  away from mold feature  1110 . In this way, moldable material  1112  bonds to workpiece  1102  only in the area defined by segregation features  1114 . 
     In some embodiments, it is desirable to deform only a portion of a workpiece within a mold to alleviate unnecessary pressure on areas of workpiece that do not require deformation.  FIGS. 12A and 12B  shows mold  1200  having shutoff valves  1214  that can be manipulated to control the flow of moldable material  1212  within mold  1200  in conjunction with opening  1208 . In particular, shutoff valves  1214  can be manipulated mid-cycle to control the flow of moldable material  1212 .  FIG. 12A  shows shutoff valves  1214  in a closed state and  FIG. 12B  shows shutoff valves  1214  in on open state. Shutoff valves  1214  can be slideably moved between a closed state ( FIG. 12A ) and an open state ( FIG. 12B ). 
     At  FIG. 12A , shutoff valves  1214  are in a closed state. Shutoff valves  1214  can be positioned on surface  1202   a  of workpiece  1202  so as to constrain the flow of moldable material  1212  within region  1204   a  of the mold cavity. As such, moldable material  1212  exerts pressure only on the portion of workpiece  1202  over and/or around mold feature  1210 . During this initial injection process, pressure P 1  of moldable material  1212  deforms workpiece  1202  in conformance with mold feature  1210 . 
     Once workpiece  1202  has been sufficiently deformed in accordance with mold feature  1210 , at  FIG. 12B  shutoff valves  1214  are moved to an open state. This allows moldable material  1212  to flow within region  1204   a  as well as region  1204   b  of the mold cavity, completing the formation of the composite part. Pressure P 2  of moldable material  1212  can be different than P 1  during the initial injection process of  FIG. 12A . For example, pressure P 1  during the initial injection can be higher than pressure P 2  during the subsequent injection. This higher pressure P 1  can be sufficient to cause workpiece  1202  to deform and conform sufficiently to mold feature  1210 . Once a desired deformation has been achieved, a lower pressure P 2  allows for moldable material  1212  to flow into region  1204   b  of the mold cavity to bond moldable material  1212  with surface  1202   a  of workpiece  1202 . 
     In some embodiments a sacrificial relief valve is used to control pressure and control the flow of moldable material.  FIGS. 13A and 13B  show mold  1300  with sacrificial relief valves  1314 .  FIG. 13A  shows sacrificial relief valves  1314  in an intact state and  FIG. 12B  shows sacrificial relief valves  1314  in a buckled state. At  FIG. 13A , sacrificial relief valves  1314  close off region  1304   a  such that moldable material  1312  flows in to region  1304   a  of the mold cavity. Moldable material  1312  is applied at pressure P 1 . Sacrificial relief valves  1314  can be coupled to or part of workpiece  1302 . For example, sacrificial relief valves  1314  can be integrally formed with workpiece  1302  and be made of the same material as workpiece  1302 . In other embodiments, sacrificial relief valves  1314  are adhered to workpiece  1302  using an adhesive, welding or other fastening mechanism. In some embodiments, sacrificial relief valves  1314  are part of mold portion  1300   a  of mold  1300 . 
     Sacrificial relief valves  1314  can be shaped to yield and buckle when the pressure of moldable material  1312  reaches a pressure P 2 , as shown in  FIG. 13B . This allows moldable material to flow into region  1304   b  of the mold cavity. In some embodiments, sacrificial relief valves  1314  have tapered bottom portions, as shown, that are designed to yield in a direction in accordance with the flow (indicated by arrows) of moldable material  1312 . Pressure P 2  at which sacrificial relief valves  1314  yield can be greater than pressure P 1  at which deformation of workpiece  1302  in conformance with mold feature  1310  occurs. For example, sacrificial relief valves  1314  can restrain moldable material  1312  at pressure P 1  sufficient to deform workpiece  1302  in conformance with mold feature  1310 . Then, the pressure is increased to P 2  sufficient to cause sacrificial relief valves  1314  to yield. In some embodiments, sacrificial relief valves  1314  remain attached to workpiece  1302  after yielding. In some embodiments, sacrificial relief valves  1314  are insert molded features of the resultant composite part. In other embodiments, sacrificial relief valves  1314  decouple from workpiece  1302  when buckled, or are removed from the composite part after the molding process is complete. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20160427
Publication Date: 20190205
Grant Date: 20190205
Priority Date: 20150622
Inventors: MESCHKE, ANDREW J.
BUSTLE, BENJAMIN SHANE
KRASS, DEREK C.
JOHANNESSEN, THOMAS
Assignee: APPLE INC
CPC Classifications: [{"code": "B29C45/1418", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29C45/14377", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2791/007", "inventive": false, "first": false, "tree": "[]"}, {"code": "B21D26/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2043/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2043/3238", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/1679", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2031/34", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49805", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2009/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49805", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49805", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K5/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29L2031/34", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2791/007", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2043/3238", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2043/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/1679", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/14377", "inventive": false, "first": false, "tree": "[]"}, {"code": "B21D26/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/1418", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29C2791/007", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2031/34", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2009/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2009/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/1418", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 57587377