Casting cup assembly for forming an ophthalmic device
Disclosed in this specification is a casting cup assembly comprising frontcurve and basecurve molds which of which includes a ring that circumscribes the respective concave and convex mold surface. When the casting cup is assembled, the rings align and minimize de-centering and tilting of the concave and convex mold surfaces which, in turn, reduces edge defects.
1. A casting cup assembly for forming an ophthalmic device, the casting cup assembly comprising:
a front curve mold comprising:
a concave mold surface disposed on a top-side of the front curve mold;
a first flat annular ring with an inner periphery and an outer periphery, wherein the inner periphery of the first flat annular ring is surrounding and contiguous with the perimeter of the concave mold surface;
a first ring disposed on said first flat annular ring forming a dam;
a first transition zone disposed on the outer periphery of said first flat annular ring; and
a first plane comprising a first plurality of flat blades, wherein the first plane is disposed on the first transition zone; and
a base curve mold comprising:
a convex mold surface disposed on a bottom-side of the base curve mold, the convex mold surface having a perimeter that is surrounded by a bottom surface;
a second flat annular ring with an inner periphery and an outer periphery;
a second transition zone disposed on the outer periphery of said second flat annular ring; and
a second plane comprising a second plurality of flat blades, wherein the second plane is disposed on the second transition zone.
2. The casting cup assembly as recited in claim 1 , wherein the concave mold surface and convex mold surface have different curvatures such that a cavity is formed between the concave mold surface and the convex mold surface when the base curve mold is disposed on the front curve mold.
3. The casting cup assembly as recited in claim 2 , wherein the second flat annular ring has a terminus that is spaced away from the surface of the first ring by a first gap when the base curve mold is disposed on the front curve mold.
4. The casting cup assembly as recited in claim 3 , wherein the first plurality of flat blades is spaced away from the second plurality of flat blades by a second gap when the base curve mold is disposed on the front curve mold.
5. The casting cup assembly of claim 4 , wherein said first plurality of flat blades comprises four flat blades and said second plurality of flat blades comprises four flat blades.
6. The casting cup assembly as recited in claim 3 , wherein the first gap is less than about 0.050 millimeters.
7. The casting cup assembly as recited in claim 4 , wherein the second gap is in the range of about 0.050 to 0.4 millimeters.
8. The casting cup assembly of claim 5 , wherein said first plurality of flat blades comprises one blade that is thicker than the other blades of said plurality.
9. The casting cup assembly of claim 5 , wherein said second plurality of flat blades comprises one blade that is thicker than the other blades of said plurality.
10. The casting cup assembly of claim 1 , wherein one of said-first plurality of flat blades has an interface with a melt delivery means.
11. The casting cup assembly of claim 10 , wherein the interface has a runner feature chosen from troughs, beveled surface, and trench before bowl.