Injection molding apparatus for producing a toric lens casting mold arbor

• US 5,110,278 A
• Filed: 11/30/1990
• Issued: 05/05/1992
• Est. Priority Date: 11/30/1990
• Status: Expired due to Term

• Current Assignee: Novartis Ag
• Original Assignee: Pilkington Visioncare Inc.
• Inventors: Bruker, Izi, Tait, John S.
• Primary Examiner(s): HEITBRINK, TIMOTHY W
• Application Number:
  US07/621,449
• Time in Patent Office: 522 Days
• Field of Search: 264/2.1, 264/2.5, 264/2.7, 264/225, 425/577, 425/808, 425/175, 425/180, 249/53 R, 249/58, 249/61, 249/144, 249/155, 249/159, 249/176
• US Class Current: 425/175
• CPC Class Codes: B24B 13/005 Blocking means, chucks or the like; Alignment devices
• CPC Class Codes: B29D 11/00942 where the lens material is mounted in a support for mounting onto a cutting device, e.g. a lathe, and where the support is of machinable material, e.g. plastics
• CPC Class Codes: Y10S 425/808 Lens mold

Abstract

Injection molding methods and apparatus for the production of casting molds for toric lenses having ballast oriented properly with respect to the cylinder axis of the toric surfaces. A calibrated rotatable ring mechanism is used within the injection molding body, for producing a slot or other alignment means on the lens casting mold at a point which is offset a predetermined number of degrees from the axis of the toric surfaces being formed in the casting mold. When the casting mold containing a newly cast lens is mounted on a precision lathe, the mating of the slot with a permanent ridge on the lathe spud ensures that the mold seats on the lathe at the same established place each time with respect to the position of the cutting tool. The offset between the toric axis and the position of the cutting tool has already been established, and therefore there is no need for the lathe operator to make any measurements or resetting of the cutting tool.

Claims

1. Injection molding apparatus for producing a lens casting mold arbor, said arbor having

i. hollow top and bottom portions separated by a finished element;

ii. exterior and interior lateral surfaces; and

iii. a bottom end surface carrying at least one alignment means for aligning said arbor on a lathe;

said injection molding apparatus comprising;

a. an injection molding body having an interior opening with a surface corresponding to said exterior lateral surface of said arbor;

b. a first core pin inserted in a bottom portion of said interior opening in said molding body, said first core pin having an external lateral surface corresponding to said interior lateral surface of said bottom portion of said arbor, said first core pin being spaced apart from said surface of said interior opening in said molding body to provide a cavity having the shape of said bottom portion of said arbor;

c. a toric core pin inserted in the upper portion of said interior opening of said molding body, said toric core pin having a bottom end shaped in the form of a toric lens curve having a predetermined toric axis, said toric core pin having an exterior lateral surface corresponding to said interior lateral surface said top portion of said arbor, said toric core pin being spaced apart from said surface of said interior opening of said molding body to provide a cavity having the shape of said top portion of said arbor, and being spaced apart from the upper end of said first core pin to provide a cavity having the shape of said finished element separating said top and bottom portions of said arbor;

d. alignment means formed in said toric core pin for mating with corresponding alignment means in the upper portion of said molding body, whereby said toric axis of said toric core pin is maintained in a stationary position;

e. a rotatable ring plate inserted in said molding body for forming said bottom end surface of said arbor, said rotatable ring plate having an upper surface corresponding to said bottom end surface of said arbor and having at least one alignment means in its said upper surface for forming said at least one alignment means in said bottom end surface of said arbor;

f. means for rotating and locking said rotatable ring plate at a point where said at least one alignment means in said ring plate is offset a predetermined number of degrees from said toric axis of said toric pin, whereby said at least one alignment means in said bottom end surface of said arbor will be offset a corresponding number of degrees from said toric axis; and

g. means for introducing resinous molding material into said cavities and applying heat and pressure to said molding material to produce said lens casting arbor.

2. The injection molding apparatus of claim 1 wherein said molding body is provided with a fixed locator pin and said rotatable ring plate is provided with a series of spaced holes around at least a portion of its circumference, said holes being adapted to mate with said locator pin in said molding body.

3. The injection molding apparatus of claim 1 wherein said alignment means in said upper surface of said rotatable ring plate is a ridge, and wherein said alignment means in said bottom end surface of said arbor is a slot.

4. Injection molding apparatus for producing a lens coating mold arbor, said arbor having

i. hollow top and bottom portions separated by a finished element;

ii. exterior and interior lateral surfaces; and

iii. a bottom end surface carrying at least one alignment means for aligning said arbor on a lathe;

said injection molding apparatus comprising;

a. a first molding body plate having an interior opening and serving as a base plate;

b. a second molding body plate, located above said first plate, having an interior opening with a lateral surface corresponding to said exterior lateral surface of said bottom portion of said arbor, said interior opening in said second molding body plate being in registration with said opening in said first plate;

c. a first core pin inserted in said openings of said first and second plates, said first core pin having an external lateral surface corresponding to said interior lateral surface of said bottom portion of said arbor, said first core pin being spaced apart from said lateral surface of said interior opening of said second molding body plate to provide a cavity having the shape of said bottom portion of said arbor;

d. a third molding body plate, located above said second plate, having an interior opening with a lateral surface corresponding to said exterior lateral surface of said top portion of said arbor, said interior opening in said third molding body plate being in registration with said interior openings in said first and second plates;

e. a toric core pin inserted in said interior opening of said third molding body plate, said toric core pin having a bottom end shaped in the form of a toric lens curve having a predetermined toric axis, said toric core pin having an exterior lateral surface corresponding to said interior lateral surface of the said top portion of said arbor, said toric core pin being spaced apart from said surface of said interior opening of said third molding body plate to provide a cavity having the shape of said top portion of said arbor, and said bottom end of said toric core pin being spaced apart from the upper end of said first core pin to provide a cavity having the shape of said finished element separating said top and bottom portions of said arbor;

f. at least one alignment ridge formed in said toric pin for mating with a corresponding alignment slot in said third plate, whereby the toric axis of said toric pin is maintained in a stationary position;

g. a rotatable ring plate inserted in said first plate for forming said bottom end surface of said arbor, said rotatable ring plate having an upper surface corresponding to said bottom end surface of said arbor and having at least one ridge in its said upper surface for forming an alignment slot in said bottom edge surface of said arbor;

h. means for rotating and locking said rotatable ring plate at a point where said ridge in said ring plate is offset a predetermined number of degrees from the toric axis of said toric pin, whereby said alignment slot in said bottom end surface of said arbor will be offset a corresponding number of degrees from said toric axis; and

i. means for introducing resinous molding material into said cavities and applying heat and pressure to said molding material to produce said lens casting arbor.

5. The injection molding apparatus of claim 4 wherein said first molding plate is provided with a fixed locator pin and said rotatable ring plate is provided with a series of spaced holes around at least a portion of its circumference, said holes being adapted to mate with said locator pin in said first molding plate.

6. The injection molding apparatus of claim 4 wherein said first, second and third molding plates are comprised of multiple sections which may be assembled and locked into place to provide a unitary molding body.