CA1119763A - Method of removing molded lenses from the mold - Google Patents
Method of removing molded lenses from the moldInfo
- Publication number
- CA1119763A CA1119763A CA000320134A CA320134A CA1119763A CA 1119763 A CA1119763 A CA 1119763A CA 000320134 A CA000320134 A CA 000320134A CA 320134 A CA320134 A CA 320134A CA 1119763 A CA1119763 A CA 1119763A
- Authority
- CA
- Canada
- Prior art keywords
- mold
- lens
- optical surface
- solid
- container
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D11/00—Producing optical elements, e.g. lenses or prisms
- B29D11/00932—Combined cutting and grinding thereof
- B29D11/00942—Combined cutting and grinding thereof 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
Landscapes
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Ophthalmology & Optometry (AREA)
- Mechanical Engineering (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
A METHOD OF REMOVING MOLDED
LENSES FROM THE MOLD
ABSTRACT OF THE DISCLOSURE:
A method of making plastic lenses by casting a liquid monomer in a container having the required optical curve on the bottom of the container, polymerizing the mono-mer to form a solid having an optical surface formed within the container and cutting a second optical surface on the solid lens material with the container supporting the lens material during the cutting and polishing operation.
Removing the lens from the casting container by applying force against the sides of the container to distort the container and stretching the surface to effect the release of the lens.
LENSES FROM THE MOLD
ABSTRACT OF THE DISCLOSURE:
A method of making plastic lenses by casting a liquid monomer in a container having the required optical curve on the bottom of the container, polymerizing the mono-mer to form a solid having an optical surface formed within the container and cutting a second optical surface on the solid lens material with the container supporting the lens material during the cutting and polishing operation.
Removing the lens from the casting container by applying force against the sides of the container to distort the container and stretching the surface to effect the release of the lens.
Description
ti;~
FIELD OF TIIE INV~NTION:
The use of plastic materials for making optical lenses has increased rapidly for the past ten years. This is due to the availability of better plastic materials and the physical advantages of the plastic resins for specific applications such as ophthalmic lenses. The technology for the production of high quality plastic lenses has not kept pace with the material supply industry. It is important to advance both areas if the full potential is to be realized.
Plastic lenses offer many advantages over glass lenses. They are much lighter in weight and resist breakage.
The cost of making high quality lenses has been high, due to the problems caused by the shrinkage of the monomer when polymerized, which often breaks the e~pensive molds.
ill97~3 The current lens molds are fabricated from steel or glass, each mold is individually ground and polished to the required specifications. To achieve accurate reproduction of the bifocal and lenticular molds is most difficult and expensive. This new process makes possible exact reproductions and has many other distinct advantages, which will become apparent from the following disclosure.
An object is to provide a process for making inexpensive molds which may be made to identical specifications.
Another object is to provide a process where by standard masters may be used to produce a large quantity of replica molds.
SUMMARY OF THE INVENTION:
In accordance with an aspect of the invention there is provided a method of casting and removing from a resinous lens mold an optical lens of polymeric material, said mold of resinous material having at one end a cup-like `~
molding cavity with an optical surface, comprising casting a monomer in the li~uid state in the molding cavity, polymerizing the monomer to form a rigid solid having a first optical surface adhering to the optical surface of the mold with sufficient adhesive strength to allow cutting and polishing of a second optical surface, cutting and polishing the surface of the polymerized solid on the side opposite the first optical surface to form a second optical surface while the polymerized solid is held by the mold, and then removing the thus formed lens from the mold by applying pressure against the mold to thereby distort the shape of the optical surface of the mold and stretch the mold material from the cast polymeric lens to thereby release the lens from the mold.
FIELD OF TIIE INV~NTION:
The use of plastic materials for making optical lenses has increased rapidly for the past ten years. This is due to the availability of better plastic materials and the physical advantages of the plastic resins for specific applications such as ophthalmic lenses. The technology for the production of high quality plastic lenses has not kept pace with the material supply industry. It is important to advance both areas if the full potential is to be realized.
Plastic lenses offer many advantages over glass lenses. They are much lighter in weight and resist breakage.
The cost of making high quality lenses has been high, due to the problems caused by the shrinkage of the monomer when polymerized, which often breaks the e~pensive molds.
ill97~3 The current lens molds are fabricated from steel or glass, each mold is individually ground and polished to the required specifications. To achieve accurate reproduction of the bifocal and lenticular molds is most difficult and expensive. This new process makes possible exact reproductions and has many other distinct advantages, which will become apparent from the following disclosure.
An object is to provide a process for making inexpensive molds which may be made to identical specifications.
Another object is to provide a process where by standard masters may be used to produce a large quantity of replica molds.
SUMMARY OF THE INVENTION:
In accordance with an aspect of the invention there is provided a method of casting and removing from a resinous lens mold an optical lens of polymeric material, said mold of resinous material having at one end a cup-like `~
molding cavity with an optical surface, comprising casting a monomer in the li~uid state in the molding cavity, polymerizing the monomer to form a rigid solid having a first optical surface adhering to the optical surface of the mold with sufficient adhesive strength to allow cutting and polishing of a second optical surface, cutting and polishing the surface of the polymerized solid on the side opposite the first optical surface to form a second optical surface while the polymerized solid is held by the mold, and then removing the thus formed lens from the mold by applying pressure against the mold to thereby distort the shape of the optical surface of the mold and stretch the mold material from the cast polymeric lens to thereby release the lens from the mold.
(2) B
~ .
:.
'7~i,L3 DESCRIPTION OF nRAWING:
Fig. 1 shows the sleeve, steel mold and resinous material.
Fig. 2 shows the resinous mo]d containing the liquid lens monomers with cover.
Fig. 3 shows the polymerized lens material with one optical surface molded on the resinous mold.
Fig. 4 shows the lens with the second optical surface cut and in the resinous mold.
THE LENSES ARE MADE AS FOLLOWS:
A master positive mold having the curvature required on the finished lens is made from glass~
stainless steel or other materials which withstand the molding pressures and temperature~ Materials which may be electroplated or plated by vacuum disposition have also been used.
DESCRIPTION OF THE PREFERRED EMBODIMF.NT:
The master mold, 1 Fig. 1 is placed in a sleeve, 4 Fig. 1, a molding grade of a resinous material such as polyimide, polycarbonate, polymethylpentene, polyethylene, polypropylene, (2a) - nylon or other molding material is placed in the sleeve, 4 Fig. 1. The sleeve and its' contents are heated to the soft-ening point of the molding material and pressure is applied to form the lens mold, 3 Fig. 1. The sides of the master mold, 1 Fig. 1, have been cut to a smaller diameter to pro-vide the opening, 5 Fig. 1. When sufficient heat and pres-sure have been applied, the molding compound, 3, will fill the area around the positive mold, 1, forming a cup-like cavity with a curved optical surface, 2 Fig. 1, at the bottom.
A concave opening, 10 Fig. 1, is provided in the rear of the negative mold. This opening may be conical, cylinderical or spherical in shape to provide for the distortion of the mold shape when sufficient pressure is applied against the sides, 11 and 12, Fig. 4, to collapse the rear of the mold.
The mold surface, 2 Fig. 4, will be stretched, releasing the lens. Either injection or compression molding may be `
~; used to produce cup, 3 Fig. 2, after removal of the master mold, 1 Fig. 1, a liquid or syrup monomer material contain-ing a suitable catalyst, 6 Fig. 2, is placed over the opti-cal surface, 2 Fig. 2, and covered to prevent evaporation with the cover, 7 Fig. 2. The space, 8 Fig. 2, is filled with nitrogen and the liquid monomer is polymerized to form a solid monolithic mass. Ultraviolet light, microwave ener-gy or heat may be used to speed the polymerization process.
Thermosetting and cross-linked hard materials may be used to produce lenses which are rigid and dimensionally stable and could not be made by injection or compression molding.
This process is also suitable for the production of soft contact lenses which cannot be made by compression or injec-tion molding techniques.
~r It is not necessary to remove the hardened plasticlens material, 6 Fig. 3, from the mold, 3 Fig. 3, before cutting the convex curve, 9 Fig. 3. The mold, 3 Fig. 3, may be placed in a - 3a -- . ~ . -.
'7~3 suita~le la~he ;lnd cllrvat~lle, 9 I-ig. 3, cut- ~nd polished. r~le finished lens, 6 Fig. 4, I-lavirlg the rnokled concave surface, 2, and ,lle conve~ curvature, 9, ~hich was cut and polished without being removed from the disposable mold, 3 Fig. 4, which acted as the holding device during the cutting and polishing of curve, 9 Fig. 4. The cup-like device has served as a container for the monomer, 6 Fig 2, provided the molded optical surface which for contact lenses may be aspheric or may be composed of two or more spherical segments providing the required optical zone and peripheral curves. The cup-like mold, 3 Fig. 3, also serves as the holding block to facilitate cutting to the required thickness.
The thickness of the cup bottom may be measured before adding the liquid monomers and measurements may be taken during the cutting operation and the lens thickness determined by subtracting the thickness of the cup bottom. The cup, 3 Fig. 3, also serves as a holding fixture during the polishing operation. The lens is supported by the optical surface present on the mold, therefore, the lens material must adhere strongly to the supporting mold in order to withstancl the forces of cutting and polishing. This adhesion may be controlled by:
1. Selecting the material from which the lens mold is made.
2. By coating the lens mold with an adhesive.
~ .
:.
'7~i,L3 DESCRIPTION OF nRAWING:
Fig. 1 shows the sleeve, steel mold and resinous material.
Fig. 2 shows the resinous mo]d containing the liquid lens monomers with cover.
Fig. 3 shows the polymerized lens material with one optical surface molded on the resinous mold.
Fig. 4 shows the lens with the second optical surface cut and in the resinous mold.
THE LENSES ARE MADE AS FOLLOWS:
A master positive mold having the curvature required on the finished lens is made from glass~
stainless steel or other materials which withstand the molding pressures and temperature~ Materials which may be electroplated or plated by vacuum disposition have also been used.
DESCRIPTION OF THE PREFERRED EMBODIMF.NT:
The master mold, 1 Fig. 1 is placed in a sleeve, 4 Fig. 1, a molding grade of a resinous material such as polyimide, polycarbonate, polymethylpentene, polyethylene, polypropylene, (2a) - nylon or other molding material is placed in the sleeve, 4 Fig. 1. The sleeve and its' contents are heated to the soft-ening point of the molding material and pressure is applied to form the lens mold, 3 Fig. 1. The sides of the master mold, 1 Fig. 1, have been cut to a smaller diameter to pro-vide the opening, 5 Fig. 1. When sufficient heat and pres-sure have been applied, the molding compound, 3, will fill the area around the positive mold, 1, forming a cup-like cavity with a curved optical surface, 2 Fig. 1, at the bottom.
A concave opening, 10 Fig. 1, is provided in the rear of the negative mold. This opening may be conical, cylinderical or spherical in shape to provide for the distortion of the mold shape when sufficient pressure is applied against the sides, 11 and 12, Fig. 4, to collapse the rear of the mold.
The mold surface, 2 Fig. 4, will be stretched, releasing the lens. Either injection or compression molding may be `
~; used to produce cup, 3 Fig. 2, after removal of the master mold, 1 Fig. 1, a liquid or syrup monomer material contain-ing a suitable catalyst, 6 Fig. 2, is placed over the opti-cal surface, 2 Fig. 2, and covered to prevent evaporation with the cover, 7 Fig. 2. The space, 8 Fig. 2, is filled with nitrogen and the liquid monomer is polymerized to form a solid monolithic mass. Ultraviolet light, microwave ener-gy or heat may be used to speed the polymerization process.
Thermosetting and cross-linked hard materials may be used to produce lenses which are rigid and dimensionally stable and could not be made by injection or compression molding.
This process is also suitable for the production of soft contact lenses which cannot be made by compression or injec-tion molding techniques.
~r It is not necessary to remove the hardened plasticlens material, 6 Fig. 3, from the mold, 3 Fig. 3, before cutting the convex curve, 9 Fig. 3. The mold, 3 Fig. 3, may be placed in a - 3a -- . ~ . -.
'7~3 suita~le la~he ;lnd cllrvat~lle, 9 I-ig. 3, cut- ~nd polished. r~le finished lens, 6 Fig. 4, I-lavirlg the rnokled concave surface, 2, and ,lle conve~ curvature, 9, ~hich was cut and polished without being removed from the disposable mold, 3 Fig. 4, which acted as the holding device during the cutting and polishing of curve, 9 Fig. 4. The cup-like device has served as a container for the monomer, 6 Fig 2, provided the molded optical surface which for contact lenses may be aspheric or may be composed of two or more spherical segments providing the required optical zone and peripheral curves. The cup-like mold, 3 Fig. 3, also serves as the holding block to facilitate cutting to the required thickness.
The thickness of the cup bottom may be measured before adding the liquid monomers and measurements may be taken during the cutting operation and the lens thickness determined by subtracting the thickness of the cup bottom. The cup, 3 Fig. 3, also serves as a holding fixture during the polishing operation. The lens is supported by the optical surface present on the mold, therefore, the lens material must adhere strongly to the supporting mold in order to withstancl the forces of cutting and polishing. This adhesion may be controlled by:
1. Selecting the material from which the lens mold is made.
2. By coating the lens mold with an adhesive.
3. By treating the mold surface with a solvent or re-lease agent prior to adding the lens material.
4. By treating the mold material with a solvent or re-lease agent before forming the material into a lens mold.
After the lens is processed to the required specifications, the lens is removed by sharply flexing the holding fixture, this is accomplished by applying pressure at points 11 and 12, Fig. 4, collapsing opening, 10 Fig. 4, and stretching surface, 2 Fig. 4.
Separating the finished optical lens, 6 Fig. 4~from it's sup-(4) 17~;~?;t. 3 Fig 4.
Various modifications can be made wi~hout dcpclrtlng rom the spirit of this invention or the scope of the appellded claims.
The constants set forth in this disclosure are given as exam.ples and are in no way final or binding. In view of the above, it will be seen that the several objects of the invention are ach-ieved and other advantages are obtained. As many changes could be made in the above constructions and methods without departing from the scope of the inven~ion, it is intended that all matter contained in the above description shall be interpreted as illus-trative and not in a limiting sense.
CHAP~ES W. NEEEE
PH: (915) 267-8214 (5?
After the lens is processed to the required specifications, the lens is removed by sharply flexing the holding fixture, this is accomplished by applying pressure at points 11 and 12, Fig. 4, collapsing opening, 10 Fig. 4, and stretching surface, 2 Fig. 4.
Separating the finished optical lens, 6 Fig. 4~from it's sup-(4) 17~;~?;t. 3 Fig 4.
Various modifications can be made wi~hout dcpclrtlng rom the spirit of this invention or the scope of the appellded claims.
The constants set forth in this disclosure are given as exam.ples and are in no way final or binding. In view of the above, it will be seen that the several objects of the invention are ach-ieved and other advantages are obtained. As many changes could be made in the above constructions and methods without departing from the scope of the inven~ion, it is intended that all matter contained in the above description shall be interpreted as illus-trative and not in a limiting sense.
CHAP~ES W. NEEEE
PH: (915) 267-8214 (5?
Claims
Claim 1.
A method of casting and removing from a resinous lens mold an optical lens of polymeric material, said mold of resinous material having at one end a cup-like molding cavity with an optical surface, comprising casting a monomer in the liquid state in the molding cavity, polymerizing the monomer to form a rigid solid having a first optical surface adhering to the optical surface of the mold with sufficient adhesive strength to allow cutting and polishing of a second optical surface, cutting and polishing the surface of the polymerized solid on the side opposite the first optical surface to form a second optical surface while the polymerized solid is held by the mold, and then removing the thus formed lens from the mold by applying pressure against the mold to thereby distort the shape of the optical surface of the mold and stretch the mold material from the cast polymeric lens to thereby release the lens from the mold.
A method of casting and removing from a resinous lens mold an optical lens of crosslinked polymeric material, said mold of resinous material having at one end a cup-like molding cavity with an optical surface and at the other end a collapsible opening comprising casting a monomer in the liquid state in the molding cavity, polymerizing the monomer to form a rigid crosslinked solid having a first optical surface adhering to the optical surface of the mold with sufficient adhesive strength to allow cutting and polishing of a second optical surface, cutting and polishing the surface of the crosslinked solid on the side opposite the first optical surface to form a second optical surface while the crosslinked solid is held by the mold, and then removing the thus formed lens from the mold by collapsing the opening in the end of the mold opposite the end having the molding cavity by applying pressure against the sides of the opening to thereby distort the shape of the optical surface of the mold and stretch the mold material from the cast crosslinked polymeric lens to thereby release the lens from the mold.
A method of casting and removing from a resinous lens mold an optical lens of polymeric material, said mold of resinous material having at one end a cup-like molding cavity with an optical surface, comprising casting a monomer in the liquid state in the molding cavity, polymerizing the monomer to form a rigid solid having a first optical surface adhering to the optical surface of the mold with sufficient adhesive strength to allow cutting and polishing of a second optical surface, cutting and polishing the surface of the polymerized solid on the side opposite the first optical surface to form a second optical surface while the polymerized solid is held by the mold, and then removing the thus formed lens from the mold by applying pressure against the mold to thereby distort the shape of the optical surface of the mold and stretch the mold material from the cast polymeric lens to thereby release the lens from the mold.
A method of casting and removing from a resinous lens mold an optical lens of crosslinked polymeric material, said mold of resinous material having at one end a cup-like molding cavity with an optical surface and at the other end a collapsible opening comprising casting a monomer in the liquid state in the molding cavity, polymerizing the monomer to form a rigid crosslinked solid having a first optical surface adhering to the optical surface of the mold with sufficient adhesive strength to allow cutting and polishing of a second optical surface, cutting and polishing the surface of the crosslinked solid on the side opposite the first optical surface to form a second optical surface while the crosslinked solid is held by the mold, and then removing the thus formed lens from the mold by collapsing the opening in the end of the mold opposite the end having the molding cavity by applying pressure against the sides of the opening to thereby distort the shape of the optical surface of the mold and stretch the mold material from the cast crosslinked polymeric lens to thereby release the lens from the mold.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US875,857 | 1978-02-07 | ||
| US05/875,857 US4155962A (en) | 1977-05-25 | 1978-02-07 | Method of removing molded lenses from the mold |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119763A true CA1119763A (en) | 1982-03-16 |
Family
ID=25366480
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000320134A Expired CA1119763A (en) | 1978-02-07 | 1979-01-23 | Method of removing molded lenses from the mold |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1119763A (en) |
| GB (1) | GB2014896B (en) |
-
1979
- 1979-01-11 GB GB7901070A patent/GB2014896B/en not_active Expired
- 1979-01-23 CA CA000320134A patent/CA1119763A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2014896B (en) | 1982-05-19 |
| GB2014896A (en) | 1979-09-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |