PATENT DOCUMENT

Publication Number: US-8342228-B2
Application Number: US-62488609-A
Country: US
Kind Code: B2

Title: Systems and methods for insert-molding

Abstract:
The present invention includes systems and methods for insert-molding. In some embodiments, a hook can be formed in a metal part by passing die-steel of a die-cast mold through the metal part during a die-casting process. This may, however, result in a hole in the metal part that is beneath the hook area. When plastic material is insert-molded over the metal part, the plastic material may flow through the hole and into the metal part. Accordingly, in some embodiments the plastic material can be prevented from flowing through the hole during the insert-molding. As one example, a tape material can be coupled over the hole. As another example, a wedge can be press-fit into the hole. As yet another example, a plug can be inserted into the hole.

Claims:
1. A method comprising:
 injecting molten metal into a die-cast mold; 
 allowing the molten metal to harden to form a metal piece; 
 passing die steel of the die-cast mold through the molten metal during the injecting; 
 removing the metal piece from the die-cast mold, wherein the metal piece comprises a hook; 
 press-fitting a wedge into a hole passing through the metal piece, wherein the hole is formed as a result of the passing of the die steel; and 
 insert-molding a plastic material onto at least a portion of the metal piece, wherein the wedge prevents the plastic material from passing through the hole during the insert-molding and a gap in the wedge allows an external part that is coupled over the hook to move at least one of towards the hole and away from the hole. 
 
     
     
       2. The method of  claim 1 , wherein the hook is formed via the passing of the die steel through the molten metal during the injecting. 
     
     
       3. A method comprising:
 injecting molten metal into a die-cast mold; 
 allowing the molten metal to harden to form a metal piece, wherein the metal piece comprises a hole passing through it and wherein the hole was formed by passing die steel of the die-cast mold through the molten metal during the injecting; 
 removing the metal piece from the die-cast mold; 
 press-fitting a wedge into the hole; 
 insert-molding a plastic material onto at least a portion of the metal piece, wherein the wedge prevents the plastic material from passing through the hole during the insert-molding, and wherein the metal piece further comprises a hook formed via the passing of the die steel through the molten metal during the injecting; and 
 coupling a moveable part over the hook, and wherein the wedge comprises a gap providing space for the moveable part to shift position. 
 
     
     
       4. A method comprising:
 injecting molten metal into a die-cast mold; 
 allowing the molten metal to harden to form a metal piece, wherein the metal piece comprises a hole passing through it and wherein the hole was formed by passing die steel of the die-cast mold through the molten metal during the injecting; 
 removing the metal piece from the die-cast mold; 
 press-fitting a wedge into the hole; and 
 insert-molding a plastic material onto at least a portion of the metal piece, wherein the wedge prevents the plastic material from passing through the hole during the insert-molding, and wherein the wedge comprises zinc. 
 
     
     
       5. A method comprising:
 injecting molten metal into a die-cast mold; 
 allowing the molten metal to harden to form a metal piece, wherein the metal piece comprises a hole passing through it and wherein the hole was formed by passing die steel of the die-cast mold through the molten metal during the injecting; 
 removing the metal piece from the die-cast mold; 
 press-fitting a wedge into the hole; and 
 insert-molding a plastic material onto at least a portion of the metal piece, wherein the wedge prevents the plastic material from passing through the hole during the insert-molding, and wherein the wedge comprises a draft angle of two degrees. 
 
     
     
       6. The method of  claim 1 , wherein the metal piece is formed from a first metal and the wedge is formed from a second metal, and wherein the second metal is softer than the first metal. 
     
     
       7. A method comprising:
 die-casting a metal piece, wherein the metal piece includes a hole associated with a hook feature of the metal piece, and wherein the hole extends from a bottom surface of the metal piece to a top surface of the metal piece; 
 press-fitting a wedge having a gap into the hole such that the wedge occupies only a portion of the hole; and 
 insert-molding a plastic material onto at least a portion of the metal piece, wherein the wedge prevents the plastic material from passing through the hole during the insert-molding. 
 
     
     
       8. The method of  claim 7 , wherein the hook feature is positioned above the hole. 
     
     
       9. The method of  claim 7 , wherein press-fitting the wedge into the hole comprises:
 press-fitting the wedge from the bottom surface of the metal piece. 
 
     
     
       10. The method of  claim 7 , wherein press-fitting the wedge into the hole comprises:
 press-fitting the wedge from the top surface of the metal piece. 
 
     
     
       11. The method of  claim 7 , wherein the plastic material comprises at least one of a thermoplastic and a thermosetting plastic. 
     
     
       12. The method of  claim 7 , wherein insert-molding the plastic material further comprises:
 forming a protective barrier on the metal piece by insert-molding the plastic material onto the at least a portion of the metal piece. 
 
     
     
       13. A method comprising:
 die-casting a metal piece, wherein the metal piece includes a hole extending from a bottom surface of the metal piece to a top surface of the metal piece; 
 press-fitting a wedge into the hole; and 
 insert-molding a plastic material onto at least a portion of the metal piece, wherein the wedge prevents the plastic material from passing through the hole during the insert-molding, and wherein the metal piece comprises a volume less than 9 millimeters cubed. 
 
     
     
       14. The method of  claim 7 , wherein the die-casting comprises:
 injecting a molten metal in a die-cast mold; 
 allowing the molten metal to harden into the metal piece; and 
 removing the metal piece from the die-cast mold after the molten metal has hardened, wherein the hole is formed by passing die steel of the die-cast mold through the molten metal during the injecting of molten metal. 
 
     
     
       15. The method of  claim 14 , wherein the die-casting further comprises:
 forming the hook feature in the metal piece via the passing of the die steel through the molten metal during the injecting of molten metal. 
 
     
     
       16. A method comprising:
 injecting molten metal into a die-cast mold; 
 allowing the molten metal to harden to form a metal piece, wherein the metal piece comprises at least one hook; 
 passing die steel of the die-cast mold through the molten metal during the injecting; 
 removing the metal piece from the die-cast mold; 
 sealing a hole passing through the metal piece, wherein the hole is formed as a result of the passing of the die steel; and 
 insert-molding a plastic material onto at least a portion of the metal piece, wherein the sealing prevents the plastic material from passing through the hole during the insert-molding and a gap in the sealing allows an external component that is coupled over the at least one hook to move within an area between the hook and the hole. 
 
     
     
       17. The method of  claim 16 , wherein the sealing includes sealing the hole with a wedge. 
     
     
       18. The method of  claim 16 , wherein the sealing includes sealing the hole with a plug.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/117,423, filed on Nov. 24, 2008, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     This relates to systems and methods for insert-molding. In particular, this relates to systems and methods for insert-molding components having apertures through which it is desirable not to have material flow. 
     BACKGROUND OF THE DISCLOSURE 
     Metal parts may often be formed through, for example, techniques such as die-casting. To perform die-casting, molten metal can be forced under high pressure into a die-cast mold of a desired pattern. The molten metal may then be allowed to cool and harden into the metal part. After the molten metal has cooled, the die-cast mold can be “opened” or otherwise removed from around the metal part. 
     In some embodiments, a metal part including a hook feature can be created via die-cast molding. However, generally a hook may not be created directly through die-cast molding. For example, since the pieces of the die-cast mold can be removed outwards from the metal part, the pieces of the mold may rip or otherwise damage the hook when these pieces are removed. Accordingly, in some embodiments, an additional machining step can be performed to create a hook in a metal part after the die cast molding. For example, a Computer Numerical Control (CNC) tool-cutter or other suitable tool can be used to cut the metal part after the die-cast molding to form a hook in the metal part. 
     Although creating a hook in a metal part through a CNC tool or through any other suitable machining step can be functional, it can have several disadvantages. For example, using a CNC tool requires an additional step to make the hook, which may cost extra time, resources, or both. As another example, due to the continual miniaturization of electronics (e.g., cellular phones becoming smaller in size, laptops becoming smaller in size, cameras becoming smaller in size, and other electronics becoming smaller in size), metal parts used in these electronics are increasingly smaller in size. As these metal parts become smaller in size, CNC tools or other such tools may improperly cut the metal part or otherwise be unable to meet the high precision required to machine these small parts. Indeed, due to the smallness and precision of these metal parts, creating features such as hooks can be very difficult or even impossible through techniques such as CNC tool machining. 
     SUMMARY OF THE DISCLOSURE 
     This is directed to systems and methods for insert-molding. 
     In some embodiments, to form a hook area in a metal part, a piece of “die steel” from a die-cast mold may be passed directly through the metal part. As used herein, the term “die steel” refers to at least a portion of the die-cast mold. This can be an efficient way of forming such an undercut since, for example, it can form a hook in a single step, it may not rip or otherwise damage the hook when the die-cast mold is removed, and it can allow for the precise creation of a hook in small, metal parts. Creating a hook in a metal part in this manner may, however, result in a hole in the metal part beneath the hook area. 
     In some embodiments, a plastic piece may be created adjacent to the metal part that includes the hook. For example, the plastic piece may be created through insert-molding plastic material over at least a portion of the metal part. In insert-molding, a plastic material (e.g., a thermoplastic, a thermo-setting plastic, or any other suitable plastic material) can be heated, and then allowed to flow over a particular item or into a mold. The plastic material can then be allowed to cool and harden. As mentioned above, however, the metal part may include a hole beneath the hook area. In some embodiments, this hole may allow the plastic material to flow into the interior of the metal part during the insert-molding. 
     In some embodiments, the plastic material can be prevented from flowing through the hole (e.g., and into the interior of the metal part) during the insert-molding. For example, a piece of “tape” or other suitable material can be coupled over the hole. As another example, a wedge can be press-fit into the hole. As yet another example, a plug can be used to prevent the plastic material from flowing through the hole. In some embodiments, this plug can be removed after the insert-molding. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
         FIG. 1  is an illustrative metal part that may be created by die-casting and a plastic material that may be insert-molded in accordance with some embodiments of the invention; 
         FIG. 2  is an illustrative system of an insert-molded plastic material that is placed over a metal part with a hook in accordance with some embodiments of the invention; 
         FIGS. 3 and 4  are illustrative systems for creating a hook in a metal part in accordance with some embodiments of the invention; 
         FIG. 5  is an illustrative system for insert-molding plastic material over a metal part with a hook in accordance with some embodiments of the invention; 
         FIG. 6  is an illustrative system for using a tape material to prevent plastic material from flowing through a hole of a metal part in accordance with some embodiments of the invention; 
         FIG. 7  is an illustrative flowchart for using a tape material to prevent plastic material from flowing through a hole in a metal part in accordance with some embodiments of the invention; 
         FIGS. 8 and 9  are illustrative systems for using a press-fit metal wedge to prevent plastic material from flowing through a hole of a metal part in accordance with some embodiments of the invention; 
         FIG. 10  is an illustrative flowchart for using a wedge to prevent plastic material from flowing through a hole in a metal part in accordance with some embodiments of the invention; 
         FIG. 11  is an illustrative system for using a plug to prevent plastic material from flowing through a hole of a metal part in accordance with some embodiments of the invention; 
         FIG. 12  is an illustrative flowchart for using a plug to prevent plastic material from flowing through a hole in a metal part in accordance with some embodiments of the invention; and 
         FIGS. 13A and 13B  are illustrative systems for a metal part with a metal boss in accordance with some embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
       FIG. 1A  shows a simplified schematic of metal part  102  that may be created by, for example, die-casting. In die-casting, a molten metal may be injected into a die-cast mold of a particular shape. For example, as shown in  FIG. 1B , molten metal  120  can be injected into a die cast mold including mold piece  130  and mold piece  132 . After molten metal  120  has solidified, the die-cast mold may be removed from the resulting metal part  102  by removing mold pieces  130  and  132  outwards. Metal part  102  may include any metal that is suitable for die-casting, such as, for example, zinc, copper, aluminum, magnesium, lead, tin based alloys, or any other suitable metal. 
     In this manner, die-casting can be used to make metal parts. Moreover, die-casting can include many benefits such as creating metal parts that are consistent, that have precise details, and that have good surface quality. Die-casting may even create metal parts with good qualities such as these when the metal parts are significantly small in size. Furthermore, as electronic devices become increasingly smaller in size (e.g., as cellular phones become smaller in size, as laptops become smaller in size, and the like), the requirement for small metal parts with high precision features can become greater. 
     In some embodiments, after metal part  102  has been die-cast, a de-flashing process may be performed in order to remove “flash” that is remaining on metal part  102 . For example, flash may be created by excess molten metal that has leaked between the two surfaces of a mold (e.g., between mold piece  130  and mold piece  132 ) during the die-casting process. 
     After metal part  102  has been created (e.g., via die-casting), metal part  102  may be covered with plastic material  106 . Plastic material  106  may, for example, improve the aesthetic appearance of, provide structural support for, provide protection for, or in any other way benefit metal part  102 . 
     In some embodiments, plastic material  106  may be adhered to metal part  102  by using an adhesive (e.g., glue or other suitable adhesive) to couple plastic material  106  to metal part  102 . For example, plastic material  106  can be separately manufactured into a desired shape, and then subsequently coupled to metal part  102 . However, coupling plastic material  106  in this manner may sometimes cause errors or be detrimental to metal part  102 . For example, metal part  102  and plastic material  106  may be misaligned when they are attached. This defect may especially be apparent or have a high chance of occurring when metal part  102  and plastic material  106  are small in size and/or have small features (e.g., if this is a metal part being used in a small, electronic device). Additionally or alternatively, the adhesive itself may degrade over time, thus causing metal part  102  and plastic material  106  to separate. 
     To avoid the undesirable results that may occur from using an adhesive, in some embodiments plastic material  106  may be insert-molded over metal part  102 . During insert-molding, the plastic can be heated to a high temperature and then injected over metal part  102 . The heated plastic may then flow over metal part  102  and, after cooling, solidify into plastic material  106 . As it solidifies, plastic material  106  can adhere at least partially to metal part  102 . In addition to the natural adherence between plastic material  106  and metal part  102 , metal part  102  can include one or more locking features to improve the connection between metal part  102  and plastic material  106 . For example, during the insert-molding the heated plastic may flow into various structures of metal part  102  (e.g., indentations or hooks) such that, after the plastic has solidified, plastic material  106  has effectively been locked to metal part  102 . 
     In some embodiments, a metal part can include a hook. For example,  FIG. 2  shows metal part  202  that may include hook  204 . Plastic material  206  can be coupled to metal part  202 . Techniques for creating hook  204  in metal part  202  will be discussed in greater detail in the discussion to follow. Hook  204  may be used, for example, to latch metal part  202  to another suitable part such as, for example, a user-pressable button, another part in an electronic device or assembly, or any other suitable part. In this manner, hook  204  may provide a locking mechanism for attaching various parts of an assembly together. 
       FIG. 3  is an illustrative system for one way of creating hook  304  in metal part  302 . Metal part  302 , hook  304 , and plastic material  306  may correspond to, for example, metal part  202 , hook  204 , and plastic material  206  of  FIG. 2 . As mentioned above, metal part  302  may be created by die-casting the metal in a die-cast mold. However, this process alone may be insufficient to create hook  304 . For example, after metal part  302  is formed by die-casting, the die-cast mold can be removed outwards from the metal part. For example, the die steel of the die-cast mold can be removed outwards in direction  308 . In this case, die steel cannot be present in the area beneath hook  304  (e.g., the area including metal material  310 ). If die steel were present in this area beneath hook  304 , hook  304  could be ripped or otherwise damaged by the die steel as the die-cast mold is removed. In some cases, it may even be impossible to remove the die-cast mold (e.g., since the die-cast mold may become “locked” to metal part  302  through hook  304 ). 
     Accordingly, in some embodiments an additional machining step can be performed after the die-casting to create hook  304 . For example, after the molten metal has hardened and the die-cast mold has been removed, there may still be metal material  310  beneath hook  304 . Hook  304  may then be formed by removing metal material  310  after metal part  302  has been die-cast. For example, metal material  310  may be selectively removed through a tool such as Computer Numerical Control (CNC) tool-cutter  312 , or removed through any other appropriate machining or manufacturing process. However, although creating a hook in a metal part in this manner can be functional, it can require an extra machining step, extra time, extra resources, or any combination of the above. Furthermore, this technique may be unable to sufficiently form hooks and other fine features in small metal parts. For example, small metal parts are often used in electronic devices such as cellular phones, personal data assistants (“PDA&#39;s”) or other electronic devices. These small metal parts may have fine or miniature features. A tool such as a CNC may not have the required amount of precision or have a small enough degree of error to sufficiently create these small metal parts. 
     Accordingly, in some embodiments, more effective and efficient ways of creating hook  304  may be realized by passing the die steel of the die-cast mold directly through metal part  302 . For example,  FIG. 4  illustrates system  400  where die steel  402  of die-cast mold  403  can be “passed” through a metal part (although not pictured in  FIG. 4  for the sake of simplicity, one skilled in the art could appreciate that mold  403  can include a suitable top mold piece, for example, similar to mold piece  130  of  FIG. 1B , that is complementary to mold  403 ). In other words, after the molten metal has been injected into mold  403  and has hardened, die steel  402  can remain passed through the hardened, metal part. In particular, after the molten metal has hardened, this technique may result in section  406  that includes hook  408  and a separate section  410  (e.g., where section  410  can be coupled to section  406  around the periphery of die steel  402 , and where section  406  and section  410  may together make up the metal part). Mold  403  may then be removed from sections  410  and  406  by removing outwardly in direction  404 . In this manner, hooks can be formed in a metal part through a single, die-casting step. 
     Moreover, as the system illustrated by system  400  can benefit from the high precision of die-casting, small metal parts can be readily created with precise and accurate features such as miniature hooks. 
     Accordingly, since the system  400  can create hook  408  without a subsequent tooling step and instead utilizes die-casting to form this hook, this may be a valuable time efficient, cost efficient, and/or precise way of creating hook  408  in a metal part. For example, since a die-cast mold can create extremely fine and precise features, this technique can create hooks or other such features in metal parts with a high degree of accuracy and precision, even when the metal parts are small in size. As an illustration, this technique can accurately create hooks and features in small metal parts such as buttons, switches, and other parts of electronic devices. For example, a metal part with hooks and other features can be accurately formed that has a volume of 240 millimeters cubed (e.g., with dimensions of 3×4×20 millimeters, or any other suitable dimensions), a volume of 100 millimeters cubed (e.g., with dimensions of 2×5×10 millimeters, or any other suitable dimensions), a volume of 9 millimeters cubed (e.g., with dimensions of 3×3×1 millimeters, or any other suitable dimensions), or from any other suitable small, metal part. However, after die steel  402  has been removed (e.g., in direction  404 ), hole  412  may exist between section  406  and section  410  of the metal part. 
     As mentioned above, insert-molding can be a beneficial way of affixing a plastic material to a metal part. Additionally, passing die steel through a metal part can be an efficient way of creating a hook in this metal part. However, as shown in  FIG. 4 , if die steel  402  is passed through the metal part to create hook  408 , this may create hole  412  in the area beneath hook  408 . Accordingly, when insert-molding of plastic material is subsequently performed after the die-casting of the metal part, the hot plastic may flow through hole  412  and into the metal part (e.g., thus potentially deterring one from performing insert-molding after forming a hook as illustrated by system  400 ). In some cases, this may even result in preventing the use of insert-molding of a plastic material after creating a hook in the manner illustrated by  FIG. 4 . 
     For example, as illustrated in  FIG. 5 , metal part  502  may be created with hook  504 . If hook  504  was created by passing die steel through metal part  502 , there may be a resultant hole  506  beneath hook  504 . Thus, when plastic material  508  is insert-molded against metal part  502 , the plastic material may flow through hole  506  and into metal part  502 . In some embodiments, during insert-molding, plastic may be prevented from flowing through holes in a metal part by passing tool steel into these holes from the inner side of metal part  502  (e.g., the side against which plastic material  508  is not placed in contact). As used herein, the term “tool steel” can refer to at least a portion of a tool used during the insert-molding process such as, for example, a portion of a mold for the insert-molding, a portion of a tool used to clamp the metal part in place during the insert molding, and the like. However, due to hook  504 , the tool steel can be blocked from entering hole  506  (e.g., from the top direction). Thus, traditional methods such as tool steel may not be able to prevent plastic material from flowing through hole  506 . Rather, alternative methods can be used for preventing the plastic from flowing through hole  506 . 
       FIG. 6  shows illustrative system  600  for preventing plastic material from flowing through a hole in a metal part during insert-molding of the plastic material. Section  606 , hook  608 , section  610 , and hole  612  may, for example, correspond to section  406 , hook  408 , section  410 , and hole  412  of  FIG. 4 , respectively. Section  606  and section  610  may, for example, be coupled together around the periphery of hole  612  and together can make up the metal part. To prevent plastic from entering through hole  612 , in some embodiments tape material  602  may be coupled over hole  612 . Tape material  602  can, for example, be coupled over hole  612  after the metal part has been die-casted and removed from the die-cast mold and before plastic material  604  has been insert-molded. In this manner, when plastic material  604  is insert-molded over the metal part, plastic material  604  may be prevented from entering hole  612  by tape material  602 . 
     Tape material  602  can include any material that can sufficiently adhere to sections  606  and  610  during the insert-molding process. For example, tape material  602  can include Mylar, Polyethylene terephthalate (PET), thin sheets of plastic, or any other suitable material. In some embodiments, tape material  602  can remain in place after plastic material  604  has been insert-molded and can become a permanent fixture between plastic material  604  and sections  606  and  610 . In this case, as illustrated by  FIG. 6 , the presence of tape material  602  may reduce the relative thickness of plastic material  604 . For example, width  614  of plastic material  604  (where tape material  602  is located) may be smaller than width  616  (where tape material  602  is not located). Accordingly, it may be beneficial to choose a tape material  602  that is substantially thin in order to allow plastic material  604  to be as thick as possible. Doing so may, for example, reduce the risk of blemishes on the exterior surface of plastic material  604 . 
       FIG. 7  shows illustrative process  700  for using a tape material to prevent plastic material from flowing through a hole in a metal part. At step  702 , a metal part including at least one hole can be formed. For example, the metal part can be formed via die-cast molding. As another example, the hole can be positioned beneath a hook feature of the metal part, where the hook and hole can be formed by passing die-steel of the die-cast mold through the metal part during the die-casting. For example, the metal part can include a hook such as hook  608  of  FIG. 6 . 
     At step  704 , a tape material (e.g., tape material  602  of  FIG. 6 ) can be coupled over the at least one hole. The tape material can include, for example, Mylar, Polyethylene terephthalate (PET), thin sheets of plastic, or any other material suitable to adhere to the metal part and cover the at least one hole. In some embodiments, one piece of tape material can be used to cover the at least one hole. For example, when two or more holes are included in the metal part, one piece of tape material can be used to cover all of these holes. In some embodiments, multiple pieces of tape material can be used to cover the at least one hole. For example, three pieces of tape material can be used to cover three holes, two pieces of tape material can be used to cover three holes (e.g., where one piece of tape material may cover two holes), two pieces of tape material can both used to cover one hole, or any other suitable number of pieces of tape material can be used. 
     At step  706 , a plastic material, such as plastic material  604  of  FIG. 6 , can be insert-molded over at least a portion of the metal part. During step  706 , the tape material can prevent the plastic material from flowing through the at least one hole (e.g., and into the metal part) during the insert-molding. 
       FIG. 8  shows illustrative system  800  for preventing plastic material from flowing through a hole in a metal part during insert-molding of the plastic material. Similar to system  600  of  FIG. 6 , section  806 , hook  808 , section  810 , and hole  812  may, for example, correspond to section  406 , hook  408 , section  410 , and hole  412  of  FIG. 4 , respectively. Section  806  and section  810  may, for example, be coupled together around the periphery of hole  812  and together can make up the metal part. 
     As illustrated by  FIG. 8 , wedge  802  may be press-fit into hole  812  after the metal part has been die-cast and before plastic material  804  has been insert-molded onto the metal part. Although wedge  802  is illustrated in  FIG. 8  as being insertable from the bottom side of the metal part (e.g., from the side of the metal part adjacent to plastic material  804 ), one skilled in the art could appreciate that wedge  802  could alternatively or additionally be press-fit from the top of the metal part or from any other suitable direction. 
     In order to press-fit two metal pieces (e.g., the wedge and the metal part) together, the two pieces can be pushed against one another and the resulting static friction may then hold these pieces together. Additionally, the forces holding these press-fit metal pieces together may be greatly increased by compressing one metal piece against the other. Thus, it may be beneficial to use softer metals during the press-fitting in order to increase the compression between these metal pieces. Accordingly, wedge  802  can include any metal suitable for press-fitting such as, for example, zinc. As zinc is a softer metal, it may readily compress and thus increase the forces holding wedge  802  within hole  812 . In some embodiments, the metal part and wedge  802  can be made from the same type of metal. For example, when section  806 , section  810 , and wedge  802  are all made of zinc (e.g., or all made of the same type of any suitable metal), corrosion or other undesirable chemical reactions may be prevented from occurring where wedge  802  contacts section  810  and  806  of the metal part. 
     Wedge  802  may additionally be fabricated with draft angle Ø 1  and draft angle Ø 2 . Draft angle Ø 1  and draft angle Ø 2  may typically be chosen to allow for a generous slope in the sides of wedge  802  (e.g., 2 degrees, 3 degrees, or any other suitable angle of slope). Draft angle Ø 1  and draft angle Ø 2  may both be the same degree or may be different degrees. This slope may, for example, beneficially allow wedge  802  to slide more smoothly into hole  812 , help mitigate errors between the size of wedge  802  and hole  812 , and allow wedge  802  to be press-fit with a smaller amount of force. 
     In some embodiments, a part operative to move up and down (e.g., or move in any other suitable direction) during its use may be placed over hook  808 . As one illustration, a part incorporated by a user-pressable button may be latched over hook  808 . During use, the user-pressable button (e.g., and the part incorporated by the button that is latched over hook  808 ) may move up and down. Thus, in some embodiments, it may be beneficial to have a gap in wedge  802  in order to allow a part placed over hook  808  sufficient leeway to move up and down. 
     As an example,  FIG. 9  illustrates wedge  902  that can include gap  920 . In  FIG. 9 , plastic material  904 , section  906 , hook  908 , and section  910  may, for example, correspond to plastic material  804 , section  806 , hook  808 , and section  810  of  FIG. 8 , respectively. Moreover, part  922  can be placed over hook  908 . Part  922  can include, for example, a user-pressable button or any other suitable part that can move during operation. As can be seen from  FIG. 9 , gap  920  can allow part  922  leeway to move up and down (e.g., or move in any other suitable direction) around hook  908 . 
       FIG. 10  shows illustrative process  1000  for using a wedge to prevent plastic material from flowing through a hole in a metal part. At step  1002 , a metal part including at least one hole can be formed. For example, the metal part can be formed via die-cast molding. As another example, the hole can be positioned beneath a hook feature of the metal part, where the hook and hole can be formed by passing die-steel of the die-cast mold through the metal part during the die-casting. For example, the metal part can include a hook such as hook  808  of  FIG. 8 . 
     At step  1004 , a wedge such as wedge  802  of  FIG. 8  can be press-fit into the at least one hole. Generally, a single wedge can be press fit into each hole of the metal part. For example, one wedge can be used when the metal part includes one hole, two wedges can be used when the metal includes two holes, and so forth. However, one skilled in the art could appreciate that any suitable number of wedges could alternatively be used for any suitable number of holes (e.g., two wedges may be placed into a single hole, and the like). 
     The wedge can include any suitable material such as zinc, a soft metal, or any other suitable metal. In some embodiments, the wedge can include draft angle Ø 1  and draft angle Ø 2  that may be any suitable angle. For example, draft angle Ø 1  and draft angle Ø 2  may be 2 degrees, three degrees, or any other suitable angle. Moreover, draft angle Ø 1  and draft angle Ø 2  may each be the same angle or may be different angles. In some embodiments, the wedge can include a gap, such as gap  920  of  FIG. 9 . The gap may, for example, allow a part coupled over a hook of the metal part to move. 
     At step  1006 , a plastic material, such as plastic material  804  of  FIG. 8 , can be insert-molded over at least a portion of the metal part. During step  1006 , the wedge can prevent the plastic material from flowing through the at least one hole (e.g., and into the metal part) during the insert-molding. 
       FIG. 11  shows illustrative system  1100  for preventing plastic material from flowing through a hole in a metal part during insert-molding of the plastic material. Similar to system  600  of  FIG. 6 , section  1106 , hook  1108 , section  1110 , and hole  1112  may, for example, correspond to section  406 , hook  408 , section  410 , and hole  412  of  FIG. 4 , respectively. Section  1106  and section  1110  may, for example, be coupled together around the periphery of hole  1112  and together can make up the metal part. 
     As illustrated in  FIG. 11 , after die-casting the metal part, plug  1102  may be inserted into hole  1112  to prevent plastic from flowing through hole  1112  during insert-molding. Although plug  1102  is illustrated in  FIG. 11  as being insertable from the top side of the metal part (e.g., from the side of the metal part not adjacent to plastic material  1104 ), one skilled in the art could appreciate that plug  1102  could alternatively or additionally be inserted from the bottom of the metal part or from any other suitable direction. 
     In some embodiments, tool steel can be used to secure plug  1102  in place during the insert-molding. For example, tool steel of a mold used during the insert-molding can be pressed against plug  1102  to hold plug  1102  in hole  1112 . In some embodiments, plug  1102  can securely remain in place on its own during the insert-molding (e.g., the friction between plug  1102  and sections  1106  and  1110  may sufficiently secure plug  1102  into hole  1112 ). 
     In some embodiments, after the insert-molding has completed and plastic material  1104  has sufficiently hardened, plug  1102  may be removed from hole  1112 . Removing plug  1102  in this manner may allow a part (e.g., a user-pressable button) that has been placed over hook  1108  sufficient leeway to move up and down into hole  1112  (e.g., as described in connection with  FIG. 9 ). Moreover, removing plug  1102  can eliminate the possibility of plug  1102  subsequently becoming loose and falling into the metal part. 
     Plug  1102  may be created from any material that may suitably block hole  1112  and withstand the high temperatures of the insert-molding process. As one example, a softer metal such as silicon may be used. 
       FIG. 12  shows illustrative process  1200  for using a plug to prevent plastic material from flowing through a hole in a metal part. At step  1202 , a metal part including at least one hole can be formed. For example, the metal part can be formed via die-cast molding. As another example, the hole can be positioned beneath a hook feature of the metal part, where the hook and hole can be formed by passing die-steel of the die-cast mold through the metal part during the die-casting. For example, the metal part can include a hook such as hook  1108  of  FIG. 11 . 
     At step  1204 , a plug, such as plug  1102  of  FIG. 11 , can be inserted into the at least one hole. Generally, a single plug can be inserted into each hole of the metal part. For example, one plug can be used when the metal part includes one hole, two plugs can be used when the metal includes two holes, and so forth. However, one skilled in the art could appreciate that any suitable number of plugs could alternatively be used for any suitable number of holes (e.g., two plugs may be placed into a single hole, and the like). 
     At step  1206 , a plastic material, such as plastic material  1104  of  FIG. 11 , can be insert-molded over at least a portion of the metal part. During step  1206 , the plug can prevent the plastic material from flowing through the at least one hole (e.g., and into the metal part) during the insert-molding. 
     At step  1208 , the plug can be removed from the at least one hole. For example, removing the plug can provide additional room for a part (e.g., coupled over a hook of the metal part) to move. Additionally or alternatively, removing the plug can eliminate the possibility of the plug loosening and subsequently falling out of the hole. 
     The processes discussed above are intended to be illustrative and not limiting. Persons skilled in the art could appreciate that steps of the processes discussed herein can be omitted, modified, combined, or rearranged, and any additional steps can be performed without departing from the scope of the invention. For example, in some embodiments, step  1208  of process  1200  can optionally be omitted and the plug may remain in the hole of the metal part. 
     In some embodiments, a metal part that has been die cast may also be created with a small projection (e.g., a boss). For example, metal part  502  of  FIG. 5  may contain boss  510  and boss  512 . To join two parts together, the head of a boss may be deformed to create a retention head that then holds these two parts together. As one example, boss  510  and boss  512  may be used to join metal part  502  to a printed circuit board. 
     In some embodiments, the boss can be made from plastic. In this case, a process known as thermal staking may be used to create the retention head. In thermal staking, the boss can be heated to soften the plastic and pressure can then be applied from above, thus deforming the top of the boss into the retention head. In some embodiments, however, the boss can be made from metal (e.g., metal boss  510  and metal boss  512  of  FIG. 5 ). In this case, thermal staking may not be an appropriate approach. 
     Accordingly, in some embodiments, a metal boss can be deformed through swaging. During a swaging process, a swage tool can be applied to the boss to plastically deform the boss and create a retention head. For example, as illustrated in  FIG. 13A , metal part  1312  can include metal boss  1314 . Swage tool  1316  may be pressed into metal boss  1314 , thus deforming and bending metal boss  1314 . As it deforms, the head of metal boss  1314  may cave outwards to create head  1318 , thus affixing metal part  1312  to another part (e.g., retaining a printed circuit board placed around boss  1314  between metal part  1312  and head  1318 ). The amount of force necessary to deform the boss and form a retention head, however, may be substantial. Moreover, there may be a risk of cracking or fracturing other components adjacent to the boss (e.g., a circuit board retained by the boss). 
     To reduce the amount of force used for the swaging process, in some embodiments a hole may first be drilled into the metal boss. For example,  FIG. 13B  shows metal boss  1320  with hole  1322  drilled along the boss axis. Because hole  1322  may reduce the axial strength of boss  1320 , hole  1322  may beneficially allow the swaging process to be performed with a smaller amount of force. Additionally, the swaging process can provide a greater amount of retention since the retention head may cave outwards by a larger amount than if, for example, hole  1322  were absent. 
     It will be apparent to those of ordinary skill in the art that methods involved in the invention may be embodied in a computer program product that includes a machine readable and/or usable medium. For example, such a computer usable medium may consist of a read-only memory device, such as a CD ROM disk or conventional ROM device, or a random access memory, such as a hard drive device or a computer diskette, or flash memory device having a computer readable program code stored thereon. 
     The above-described embodiments of the invention are presented for purposes of illustration and not of limitation.

Metadata:
Filing Date: 20091124
Publication Date: 20130101
Grant Date: 20130101
Priority Date: 20081124
Inventors: SANFORD EMERY
HOLMAN ED
Assignee: APPLE INC
CPC Classifications: [{"code": "B29K2705/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/14778", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29C45/14336", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C45/14336", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C45/14778", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29K2705/00", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 42239134