Core locking assembly and method for orientation of asymmetric tooling

• US 7,935,280 B2
• Filed: 07/30/2009
• Issued: 05/03/2011
• Est. Priority Date: 12/30/2004
• Status: Active Grant

• Current Assignee: Bruce E. Lawton, Daniel P. Barrows
• Original Assignee: Bruce E. Lawton, Daniel P. Barrows
• Inventors: Barrows, Daniel P., Lawton, Bruce E.
• Primary Examiner(s): Del Sole; Joseph S
• Assistant Examiner(s): BODAWALA, DIMPLE N
• Application Number:
  US12/512,293
• Publication Number:
  US 20090289383A1
• Time in Patent Office: 642 Days
• Field of Search: 264/1.32, 264/219, 425/190, 425/192.R, 425/193, 425/195, 425/547, 425/556, 425/595, 425/577, 425/408, 425/451.9, 425/467, 425/468, 425/808, 249/63, 249/175, 249/177, 249/182, 164339-341, 164/397
• US Class Current: 264/1.32
• CPC Class Codes: B29C 45/2606 Guiding or centering means
• CPC Class Codes: B29C 45/2675 Mounting of exchangeable mould inserts
• CPC Class Codes: B29D 11/00125 Auxiliary operations, e.g. removing oxygen from the mould, conveying moulds from a storage to the production line in an inert atmosphere
• CPC Class Codes: B29D 11/0048 Moulds for lenses moulds for plastic articles in general B29C33/00
• CPC Class Codes: B29L 2011/0041 Contact lenses
• CPC Class Codes: Y10S 425/808 Lens mold

Abstract

An apparatus and method is provided for injection molding an ophthalmic lens mold section having an optical surface and a non-optical surface opposite the optical surface. The apparatus includes a non-optical tool assembly for forming the non-optical surface of the ophthalmic lens mold section. An optical tool assembly is in opposed relation to the non-optical tool assembly and together therewith forms a mold cavity for forming the ophthalmic lens mold section. In the preferred embodiment, the optical tool assembly includes a rotatably mounted core member and an optical insert removably secured the core member. The optical insert has an optical molding surface for forming an optical surface of the ophthalmic lens mold section opposite the non-optical surface thereof. A locking mechanism having, in a preferred embodiment, a locking pin selectively movable between a first position wherein the pin allows rotation of the core member and a second position wherein the pin prevents the core member from rotation.

Claims

1. A method for forming an ophthalmic lens, comprising the steps of:

providing an injection molding apparatus having a non-optical tool assembly for forming the non-optical surface of the ophthalmic lens mold section and an optical tool assembly in opposed relation to said non-optical tool assembly that together therewith forms a mold cavity for forming the ophthalmic lens mold section, said optical tool assembly includes a rotatably mounted core member;

an optical insert removably secured to said core member, said optical insert having an optical molding surface for forming an optical surface of the ophthalmic lens mold section opposite the non-optical surface; and

a locking mechanism selectively operable between an unlocked position and a locked position, wherein when in said unlocked position, said core member may be freely rotated, and when in said locked position said core member is in a selected rotatably fixed position;

injection molding said ophthalmic lens mold section in said mold cavity;

removing said molded ophthalmic lens mold section from said mold cavity;

matching said ophthalmic lens mold section with a mating ophthalmic lens mold section; and

cast molding an ophthalmic lens between said ophthalmic lens mold sections.

2. The method of claim 1 wherein said locking mechanism includes a locking pin and circumferentially spaced holes defined in said core member for receipt of said locking pin when in said locked position.

3. The method of claim 2 wherein each of said holes is positioned to be selectively, individually alignable with said locking pin by rotating said core member when said locking mechanism is in said unlocked position.

4. The method of claim 2 wherein said holes are defined in a proximal end of said core member.

5. The method of claim 1 wherein said locking mechanism is a solenoid-actuated locking pin that spring biases said pin in an extended position wherein said pin may be received in a selected one of a plurality of circumferentially spaced holes defined in said core member and thereby lock said core member in a rotatably fixed position, and movable, upon actuation of said solenoid-actuated locking pin, to a retracted position to allow rotation of said core member to a selected rotational position.

6. The method of claim 1 wherein said locking mechanism communicates the position of said locking pin to an associated injection molding machine to prevent injection molding when said locking pin is in said first position.

7. The method of claim 1 and further including a roller bearing assembly disposed adjacent said rotatably mounted core assembly to facilitate rotation thereof.

8. The method of claim 1 wherein said optical molding surface is a rotationally asymmetric molding surface.

9. The method of claim 1 wherein said core member includes a bore having internal threads which are threadedly engaged to threads on said optical insert which is received in said bore.

10. The method of claim 9 wherein said core member defines a cooling cavity spaced from said bore into which a cooling fluid is directed from cooling lines.

11. The method of claim 1 wherein said optical tooling assembly further includes:

a stripper member annularly received about said core member and moveable toward said non-optical tool assembly for removing a molded ophthalmic lens mold section from said optical insert.

12. The method of claim 1 wherein said mold cavity is shaped to form the ophthalmic lens mold as one of a posterior lens mold or an anterior lens mold.

13. A method for forming an ophthalmic lens, comprising the steps of:

providing an injection molding apparatus for forming a mold section which is subsequently used for forming an ophthalmic lens having an asymmetric surface, said injection molding apparatus having a core member rotatably mounted to an associated first mold plate;

an optical tool insert removably mounted to said core member, said optical tool insert having an asymmetric molding surface with an optical quality finish for forming an optical surface of the mold section;

a locking mechanism mounted to the associated first mold plate to allow toggling of said core member with said optical tool insert mounted thereto between being a fixed, selected rotational position and an alternate selected rotational position;

a non-optical tool mounted to an associated second mold plate opposite the associated first mold plate, said non-optical insert having a molding surface for forming a surface of the mold section opposite the optical surface; and

a water jacket surrounding said non-optical tool and mounted to the associated second mold plate;

injection molding said ophthalmic lens mold section in said mold cavity;

removing said molded ophthalmic lens mold section from said mold cavity;

matching said ophthalmic lens mold section with a mating ophthalmic lens mold section; and

cast molding an ophthalmic lens between said ophthalmic lens mold sections.

14. The method of claim 13 wherein said optical tool insert, said non-optical tool and said water jacket together form a mold cavity shaped to mold the mold section.

15. The method of claim 13 wherein said locking mechanism is a solenoid-actuated locking pin that is spring biased to an engaged position wherein said pin is received in one of a plurality of circumferentially spaced holes defined in said core member to rotatably lock said core member, and movable to a retracted position to allow rotation of said core member upon actuation of said solenoid-actuated locking pin.

16. The method of claim 13 wherein said water jacket and a stripper member annularly received about said core member and moveable toward said non-optical tool assembly for removing a molded ophthalmic lens mold from said optical insert together define a runner fluidly connected to said mold cavity for allowing molten resin to be injected into said mold cavity when injection molding the mold section.

17. The method of claim 13 wherein said core member is rotatable to align said asymmetric molding surface with a runner defined by at least one of said optical and non-optical tool assemblies.

18. A method for forming an ophthalmic lens, comprising the steps of:

providing an injection molding apparatus for forming a mold section which is subsequently used for forming an ophthalmic lens mold, said injection molding apparatus having a non-optical tool assembly for forming the non-optical surface of the ophthalmic lens mold;

a rotatably mounted optical tool assembly in opposed relation to said non-optical tool assembly that together therewith forms a mold cavity for forming the ophthalmic lens mold, said optical tool assembly includes an asymmetric optical molding surface for forming an optical surface of the ophthalmic lens mold opposite the non-optical surface; and

a locking mechanism having a locking pin selectively receivable in one of a plurality of circumferentially spaced holes defined in said rotatably mounted optical tool assembly to rotatably lock said optical tool assembly in a selected rotative position;

injection molding said ophthalmic lens mold section in said mold cavity;

removing said molded ophthalmic lens mold section from said mold cavity;

matching said ophthalmic lens mold section with a mating ophthalmic lens mold section; and

cast molding an ophthalmic lens between said ophthalmic lens mold sections.