Metal alloy injection molding overflows

• US 9,027,631 B2
• Filed: 12/14/2012
• Issued: 05/12/2015
• Est. Priority Date: 10/17/2012
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Bornemann, Paul C., Master, Raj N., Lane, Michael Joseph, Too, Seah Sun
• Primary Examiner(s): Yoon, Kevin E
• Application Number:
  US13/715,229
• Publication Number:
  US 20140166227A1
• Time in Patent Office: 879 Days
• Field of Search: 164/113, 164/284, 164/303, 164/312, 164/359, 164/360
• US Class Current: 164/113
• CPC Class Codes: B22D 17/00 Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
• CPC Class Codes: B22D 17/08 Cold chamber machines, i.e. with unheated press chamber into which molten metal is ladled
• CPC Class Codes: B22D 17/14 Machines with evacuated die cavity
• CPC Class Codes: B22D 17/20 Accessories: Details
• CPC Class Codes: B22D 17/22 Dies manufacture, see the appropriate class, e.g. B23P15/24; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
• CPC Class Codes: B22D 17/2272 Sprue channels
• CPC Class Codes: B22D 17/32 Controlling equipment

Abstract

Metal alloy injection molding techniques are described. In one or more implementations, these techniques may also include adjustment of injection pressure, configuration of runners, and/or use of vacuum pressure, and so on to encourage flow of the metal alloy through a mold. Techniques are also described that utilize protrusions to counteract thermal expansion and subsequent contraction of the metal alloy upon cooling. Further, techniques are described in which a radius of edges of a feature is configured to encourage flow and reduce voids. A variety of other techniques are also described herein.

Claims

1. A method comprising:

injection molding an article using a metal alloy comprised primarily of magnesium using a molding device having a plurality of molding portions that form;

a cavity that defines an article to be molded using the metal alloy; and

one or more overflows that are positioned to bias flow of the metal alloy toward one or more features with protrusions opposite the features, the protrusions sized to counteract shrinkage of the article; and

removing the metal alloy collected in the one or more overflows from the metal alloy molded using the cavity to form the article.

2. A method as described in claim 1, wherein the features have a height that is greater than a thickness of a wall of the article that does not include the features.

3. A method as described in claim 2, wherein the features have a height that is less than the height of a perimeter of the article.

4. A method as described in claim 2, the features comprising one or more features that taper in width.

5. A method as described in claim 2, the features comprising one or more features having a circular cross section at the intersection of the feature and the wall.

6. A method as described in claim 2, the features comprising one or more features having a rectangular cross section at the intersection of the feature and the wall.

7. A method as described in claim 2, the features comprising a first feature having a circular cross section at the intersection of the first feature and the wall and a second feature having a rectangular cross section at the intersection of the second feature and the wall.

8. A method as described in claim 1, wherein at least one of the one or more overflows is positioned at a part of the cavity that is further away from a point at which the metal alloy is injected into the cavity than another part of the cavity that is not disposed proximal to the one or more overflows.

9. A method as described in claim 1, wherein at least one of the one or more overflows is positioned at a part of the cavity that defines features that cause increased turbulence to a flow of the metal alloy through the cavity than another part of the cavity that is not disposed proximal to the one or more overflows.

10. A method as described in claim 1, wherein the article is configured to have a thickness of less than one millimeter.

11. A method as described in claim 1, wherein the article is configured to have a length of at least 100 millimeters.

12. A method as described in claim 1, the injection molding further comprising using a vacuum device to create a negative pressure within the cavity, wherein the vacuum device is coupled to the molding portions at a location corresponding to the overflows.

13. A method as described in claim 1, wherein the cavity further defines one or more additional features along an edge of the article.

20. A method as described in claim 1, wherein the article is configured to have a thickness of less than one millimeter and a length of at least 100 millimeters.

14. A method comprising:

injection molding an article using a metal alloy comprised primarily of magnesium using a molding device having a plurality of molding portions that form;

a cavity that defines an article to be molded using the metal alloy, including protrusions sized to counteract shrinkage of the article; and

one or more overflows that are positioned to bias flow of the metal alloy toward one or more corners of the cavity; and

removing the metal alloy collected in the one or more overflows from the metal alloy molded using the cavity to form the article.

15. A method as described in claim 14, wherein the article is configured to have a length of at least 100 millimeters.

16. A method as described in claim 14, wherein the article is configured to have a thickness of less than one millimeter.

17. A method comprising:

injection molding an article using a metal alloy comprised primarily of magnesium using a molding device having a plurality of molding portions that form;

a cavity that defines an article to be molded using the metal alloy, the article comprising a wall, a perimeter having a thickness greater than the wall, two or more features having a thickness greater than the wall, and protrusions opposite the features, the protrusions sized to counteract shrinkage of the article; and

one or more overflows that are positioned to bias flow of the metal alloy toward parts of the cavity that correspond to the overflows; and

removing the metal alloy collected in the one or more overflows from the metal alloy molded using the cavity to form the article.

18. A method as described in claim 17, wherein the article is configured to have a length of at least 100 millimeters.

19. A method as described in claim 17, wherein the article is configured to have a thickness of less than one millimeter.