CA1049818A - Apparatus for the manufacture of contact lenses - Google Patents
Apparatus for the manufacture of contact lensesInfo
- Publication number
- CA1049818A CA1049818A CA295,342A CA295342A CA1049818A CA 1049818 A CA1049818 A CA 1049818A CA 295342 A CA295342 A CA 295342A CA 1049818 A CA1049818 A CA 1049818A
- Authority
- CA
- Canada
- Prior art keywords
- blank
- support
- lens
- tool
- machine
- 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
Landscapes
- Turning (AREA)
- Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The specification describes an apparatus for manufacturing a contact lens from a lens blank, the machine comprising a lens blank support rotatable about an axis, a first material removal tool mounted on a radius arm and arranged to traverse the support in an arc about an axis to form a first curved lens surface on a blank held by the support and a second material removal tool arranged to be movable radially of the support into engagement with the blank so as to machine a generally frusto-conical peripheral surface defining with the first curved surface a peripheral portion of substantially uniform circumferential thickness, the support and the tools being arranged so that the machining movements of both tools may be effected without removing the blank from the support.
The specification describes an apparatus for manufacturing a contact lens from a lens blank, the machine comprising a lens blank support rotatable about an axis, a first material removal tool mounted on a radius arm and arranged to traverse the support in an arc about an axis to form a first curved lens surface on a blank held by the support and a second material removal tool arranged to be movable radially of the support into engagement with the blank so as to machine a generally frusto-conical peripheral surface defining with the first curved surface a peripheral portion of substantially uniform circumferential thickness, the support and the tools being arranged so that the machining movements of both tools may be effected without removing the blank from the support.
Description
--- . 1049818 This invention relates ~o the manufacture of so-called soft contact lenses, namely lenses formed from hydrophilic polymeric materials in the form of a gel and containing a sub-- stantial proportion of water. Examples of such swollen hy-drogels are found in Canadian Application No. 201,017 filed May 28, 1974 and elsewhere.
Contact lenses are currently produced by a machining or moulding process from lens blanks formed of the appropriate plastic hydrogel in a substantially non-hydrated condition so that the blanks are sufficiently hard to be worked to form the lens. After working is complete the lens is immersed in a suitable liquid to bring it to the soft condition as known to those skilled in this art. In one current machining process, a lens lathe is employed to machine a first curved lens surface , on the blank, the blank is removed and repositioned and the second lens surface is machined. The circumferential edge surface is formed by the intersection of the first and second curved surfaces, or by shearing through the peripheral portion of the partly formed lens. The resulting circumferential edge surface then generally has to be polished to the desired profile and dimensions. Alternatively, a yet further machining operation is performed on the partly formed lens in a
Contact lenses are currently produced by a machining or moulding process from lens blanks formed of the appropriate plastic hydrogel in a substantially non-hydrated condition so that the blanks are sufficiently hard to be worked to form the lens. After working is complete the lens is immersed in a suitable liquid to bring it to the soft condition as known to those skilled in this art. In one current machining process, a lens lathe is employed to machine a first curved lens surface , on the blank, the blank is removed and repositioned and the second lens surface is machined. The circumferential edge surface is formed by the intersection of the first and second curved surfaces, or by shearing through the peripheral portion of the partly formed lens. The resulting circumferential edge surface then generally has to be polished to the desired profile and dimensions. Alternatively, a yet further machining operation is performed on the partly formed lens in a
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" 104~818 lens-edging machine, to machine the desired circumferential edge surface. This involves a further re-positioning step in a machine.
One object of the present invention is to provide an apparatus for manufacturing a contact lens in which a circumferential edge lens surface of desired ~rofile, dimen-sion, and accuracv may more readily be achieved and reproduced.
Canadian Patent Application Serial N~. 210,694, filed on October 3, 1974, of which this is a division, is directed to a method of manufacturing a contact lens and the lens manufactured thereby. The present invention is directed to a machine for manufacturing a contact lens from a contact lens blank.
The present invention may be broadly defined as , a contact lens lathe for manufacturing a contact lens from a lens blank, the lathe comprising a lens blank support rotatable about an axis passing through the support blank, a fir~t material removal tool mounted on a radius arm and arranged to t~averse the support in an arc about an axis to form a first curved lens surface on a blank held by the support, and a second material removal tool arranged to be - movable radially of the support into engagement with the blank so as to machine a generally frusto-conical peripheral surface defining with the first curved surface a peripheral portion of substantially uniform circumferential thickness, the support and the tools being arranged so that the machining movements of both tools may be effected without removing such blank from the support.
Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings in which:
- : , . . - . . .
.. ~ . - . .
' .
' FI~,URES 1, 2, 3, 4, 5, 6, 7, ~ and 9 show schematical-ly inside elevation consecutive steps in the manufacture of a soft contact lens accordinq to the invention, the curvature of the lens being rather exaggerated to assist explanation;
FIGURE 4A shows a modification of the step of FIGURE
4; and, FIGURE 10 iS a schematic plan view of a machine according to the invention for machining contact lenses.
Referring to the drawings, FIGURE 1 shows a lens blank 10 of the appropriate plastic material in a machinable condition as discussed above. The blank 10 is mounted to a rotatable support 11, suitabl~ by means of a thermo-104981~, plastic adhesive 12. The support 11 is adapted for receptionin a chuck or -the like of a material removal machine such as a lens lathe. A particular preferred machine for carrying out the invention will be described below with reference to FIGURE 10. The blank 10 is preferably in the form of a right circular cylinder with a pre-moulded dished end 13.
It will be understood that the soft contact lenses in their finished form, as shown in FIGURE 9, present a concave lens surface 90 intended in use to sit peripherally against the eye ball, an opposite convex lens surface 91 of appropriate curvature to ameliorate the vision defect of the user and a circumferential edge surface 92 of tangible thickness. A frusto-conical surface 93 is also preferably provided and all the boundaries between the surfaces 90,91,92 and 93 are polished to a smooth condition.
Referring back to FIGURE 1 a first step is preferably to reduce the blank 10, or at least a portion of the length thereof, to a desired diameter, e.g. 7 mm. This step also serves accurately to centre the rotating blank. The machine may be effected by axial , . .:: .
traversal of a cutting tool 14 a while the supported blank 10 is :. :. , .
; 20 rotated about its longitudinal axis by the machine.
..
Referring to FIGURE 2 the first concave lens surface 90 is machined by traversal of a radius cutting tool 20 in an arc about an axis 21.
Referring to FIGURE 3 an edge forming tool 30 machines the desired circumferential edge surface 92 on the rotating sup-ported blank 10. The tool 30 is conveniently fed forwards into material moving engagement with the blank immediately after the tool 20 has finished each traverse in its machining of surface 90 as shown in Fig. 3. The tool 30 is conveniently mounted on a pb - 5 -104981~
radius arm together with tool 20 to pivot about the same axis 21.
The lens blank material in its hard machinable state is somewhat brittle and for best results care is taken to traverse the tool 30 at controlled speed.
One defect of the currently used process is that it is difficult to machine an accurate edge surface after machining both the curved lens surfaces. In the method according to the present invention it will be appreciated that the circumferential edge surface 92 is machined while still bodily supported by the bulk 32 of the blank material behind the edge surface 92. That material 32 is then subsequently machined away to provide the convex surface 91 as will be described below. In addition, it will be appreciated that both the concave surface 90 and the edge surface 92 are machined without removing and repositioning the blank in the machine. ~hat leads to enhanced accuracy in profile and dimensions of the edge surface 92, to enhanced accuracy in positioning of surface 92 relative to surfaces 90 and 91, and to enhanced ease in achievement and reproduceability of a desired surface 92.
It is possible in an alternative embodiment to machine the convex surface 91 and the edge surface 92 while the blank is in its first supported position and then subsequently to machine the concave surface 90: however the particularily described and illustrated method is preferred at the present time.
Referring to FIGURE 4, a further tool 40 is then moved radially in to work on the rotating partly formed lens to machine a frusto-conical surface 93 and simultaneously to machine a right circular cylindrical surface 41. As with the edging step shown in FIGURE 3 the best results are achieved by taking care to feed pb - 6 -- : -, .. .
; . :
104981~
tool 40 at a controlled speed in view of the thinness of the tangible edge of the lens.
As shown in FIGURE 5, the circumferential boundaries 50 between the concave surface 90 and the edge surface 92, and between the edge surface 92 and -the frusto-conical surface 93 are then polished to round them slightly.
Referring to FIGURE 6, the polished partly-worked blank from FIGURE 5 is moved from its support 11 and re-positioned the other way round with machined concave surface 90 stuck e.g.
with thermoplastic adhesive 60 to a second support 61. A micro-scope 62 is then used to view the crown 63 of the concavity through the body of the material (which is of course transparent) perpendicular to the lens axis, as shown by vision line 64. The microscope is mounted to the machine and thus its position can be accurately determined by a dial gauge or the like when the crown 63 is centered in the cross-wires of the microscope. This use of a microscope 62 eliminates the necessity for physical measure-ments on the lens at this stage.
Referring to FIGURE 7, a further tool 70 is then set 20 in accordance with the indication of the position of the micro-scope 62, and traversed as shown by arrows 71 about axis 72 to machine the convex lens surface 91.
The machined lens 80 is then removed from the support 61 and boundaries 81 between the surface 91 and frusto-conical surface 93 are polished, to result in the finished machined lens 90 shown in FIGURE 9. As known to those in the art, the lens 90 is then swollen in a saline solution or the alkaline salt solu-tion described in the aforementioned Canadian application Serial ~o. 201,017, to achieve its operative soft position.
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1049~3~8 Thetools referred to are preferably diamond cutters but tungsten carbide or steel tools may sometimes be used instead.
FIGURE 4A shows a modification in which a tool 45 is substituted for tool 40. As shown this forms only the frusto-eonieal surface 93. The mieroscope 62 can then be positioned to view the crown 63 through the original substantially eylindrieal blank surface 46 if desired.
Referring to FIGURE 10 there is shown very schemati-eally a maehine for making soft contact lenses according to the invention. The machine bed is basically that of a lens lathe and eomprises a motor 100 for rotating a ehuck 101 on a head stoek 102. The ehuek 101 is shown gripping the support 11 of FIGURES 1 to 5. ~ools 20 and 30 are shown mounted on a table 103 on a radius arm 104 for movement as deseribed about axis 21.
The tools are adjustable as shown by arrows 105, 106 ana 107, and gauges 108 indieate their longitudinal positions. Tool 40 and mieroseope 62 are movable as shown by arrows 109 and 110.
An adjustable tool 111 serves to reduee the original blank 10 to a desired diameter as a first step as deseribed. The surfaee93 may be maehined slightly rounded by appropriate shaped tools 40,45.
This applieation is a division of eo-pending Canadian Patent Applieation Serial No. 210,694, filed on Oetober 3, 1974.
pb - 8 -.. , , .. . . ~ , : . . - , , - - - : :
::
. ' :
.. , ,~ , . : ~ ' .-. .
. , . ; : , . . :
- ,, ~ . ' : : ,: ~ : , .
,. ,, , . ~ .
" 104~818 lens-edging machine, to machine the desired circumferential edge surface. This involves a further re-positioning step in a machine.
One object of the present invention is to provide an apparatus for manufacturing a contact lens in which a circumferential edge lens surface of desired ~rofile, dimen-sion, and accuracv may more readily be achieved and reproduced.
Canadian Patent Application Serial N~. 210,694, filed on October 3, 1974, of which this is a division, is directed to a method of manufacturing a contact lens and the lens manufactured thereby. The present invention is directed to a machine for manufacturing a contact lens from a contact lens blank.
The present invention may be broadly defined as , a contact lens lathe for manufacturing a contact lens from a lens blank, the lathe comprising a lens blank support rotatable about an axis passing through the support blank, a fir~t material removal tool mounted on a radius arm and arranged to t~averse the support in an arc about an axis to form a first curved lens surface on a blank held by the support, and a second material removal tool arranged to be - movable radially of the support into engagement with the blank so as to machine a generally frusto-conical peripheral surface defining with the first curved surface a peripheral portion of substantially uniform circumferential thickness, the support and the tools being arranged so that the machining movements of both tools may be effected without removing such blank from the support.
Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings in which:
- : , . . - . . .
.. ~ . - . .
' .
' FI~,URES 1, 2, 3, 4, 5, 6, 7, ~ and 9 show schematical-ly inside elevation consecutive steps in the manufacture of a soft contact lens accordinq to the invention, the curvature of the lens being rather exaggerated to assist explanation;
FIGURE 4A shows a modification of the step of FIGURE
4; and, FIGURE 10 iS a schematic plan view of a machine according to the invention for machining contact lenses.
Referring to the drawings, FIGURE 1 shows a lens blank 10 of the appropriate plastic material in a machinable condition as discussed above. The blank 10 is mounted to a rotatable support 11, suitabl~ by means of a thermo-104981~, plastic adhesive 12. The support 11 is adapted for receptionin a chuck or -the like of a material removal machine such as a lens lathe. A particular preferred machine for carrying out the invention will be described below with reference to FIGURE 10. The blank 10 is preferably in the form of a right circular cylinder with a pre-moulded dished end 13.
It will be understood that the soft contact lenses in their finished form, as shown in FIGURE 9, present a concave lens surface 90 intended in use to sit peripherally against the eye ball, an opposite convex lens surface 91 of appropriate curvature to ameliorate the vision defect of the user and a circumferential edge surface 92 of tangible thickness. A frusto-conical surface 93 is also preferably provided and all the boundaries between the surfaces 90,91,92 and 93 are polished to a smooth condition.
Referring back to FIGURE 1 a first step is preferably to reduce the blank 10, or at least a portion of the length thereof, to a desired diameter, e.g. 7 mm. This step also serves accurately to centre the rotating blank. The machine may be effected by axial , . .:: .
traversal of a cutting tool 14 a while the supported blank 10 is :. :. , .
; 20 rotated about its longitudinal axis by the machine.
..
Referring to FIGURE 2 the first concave lens surface 90 is machined by traversal of a radius cutting tool 20 in an arc about an axis 21.
Referring to FIGURE 3 an edge forming tool 30 machines the desired circumferential edge surface 92 on the rotating sup-ported blank 10. The tool 30 is conveniently fed forwards into material moving engagement with the blank immediately after the tool 20 has finished each traverse in its machining of surface 90 as shown in Fig. 3. The tool 30 is conveniently mounted on a pb - 5 -104981~
radius arm together with tool 20 to pivot about the same axis 21.
The lens blank material in its hard machinable state is somewhat brittle and for best results care is taken to traverse the tool 30 at controlled speed.
One defect of the currently used process is that it is difficult to machine an accurate edge surface after machining both the curved lens surfaces. In the method according to the present invention it will be appreciated that the circumferential edge surface 92 is machined while still bodily supported by the bulk 32 of the blank material behind the edge surface 92. That material 32 is then subsequently machined away to provide the convex surface 91 as will be described below. In addition, it will be appreciated that both the concave surface 90 and the edge surface 92 are machined without removing and repositioning the blank in the machine. ~hat leads to enhanced accuracy in profile and dimensions of the edge surface 92, to enhanced accuracy in positioning of surface 92 relative to surfaces 90 and 91, and to enhanced ease in achievement and reproduceability of a desired surface 92.
It is possible in an alternative embodiment to machine the convex surface 91 and the edge surface 92 while the blank is in its first supported position and then subsequently to machine the concave surface 90: however the particularily described and illustrated method is preferred at the present time.
Referring to FIGURE 4, a further tool 40 is then moved radially in to work on the rotating partly formed lens to machine a frusto-conical surface 93 and simultaneously to machine a right circular cylindrical surface 41. As with the edging step shown in FIGURE 3 the best results are achieved by taking care to feed pb - 6 -- : -, .. .
; . :
104981~
tool 40 at a controlled speed in view of the thinness of the tangible edge of the lens.
As shown in FIGURE 5, the circumferential boundaries 50 between the concave surface 90 and the edge surface 92, and between the edge surface 92 and -the frusto-conical surface 93 are then polished to round them slightly.
Referring to FIGURE 6, the polished partly-worked blank from FIGURE 5 is moved from its support 11 and re-positioned the other way round with machined concave surface 90 stuck e.g.
with thermoplastic adhesive 60 to a second support 61. A micro-scope 62 is then used to view the crown 63 of the concavity through the body of the material (which is of course transparent) perpendicular to the lens axis, as shown by vision line 64. The microscope is mounted to the machine and thus its position can be accurately determined by a dial gauge or the like when the crown 63 is centered in the cross-wires of the microscope. This use of a microscope 62 eliminates the necessity for physical measure-ments on the lens at this stage.
Referring to FIGURE 7, a further tool 70 is then set 20 in accordance with the indication of the position of the micro-scope 62, and traversed as shown by arrows 71 about axis 72 to machine the convex lens surface 91.
The machined lens 80 is then removed from the support 61 and boundaries 81 between the surface 91 and frusto-conical surface 93 are polished, to result in the finished machined lens 90 shown in FIGURE 9. As known to those in the art, the lens 90 is then swollen in a saline solution or the alkaline salt solu-tion described in the aforementioned Canadian application Serial ~o. 201,017, to achieve its operative soft position.
pb - 7 -: .~ .. ". .
-:' . , : ~ : ., .
1049~3~8 Thetools referred to are preferably diamond cutters but tungsten carbide or steel tools may sometimes be used instead.
FIGURE 4A shows a modification in which a tool 45 is substituted for tool 40. As shown this forms only the frusto-eonieal surface 93. The mieroscope 62 can then be positioned to view the crown 63 through the original substantially eylindrieal blank surface 46 if desired.
Referring to FIGURE 10 there is shown very schemati-eally a maehine for making soft contact lenses according to the invention. The machine bed is basically that of a lens lathe and eomprises a motor 100 for rotating a ehuck 101 on a head stoek 102. The ehuek 101 is shown gripping the support 11 of FIGURES 1 to 5. ~ools 20 and 30 are shown mounted on a table 103 on a radius arm 104 for movement as deseribed about axis 21.
The tools are adjustable as shown by arrows 105, 106 ana 107, and gauges 108 indieate their longitudinal positions. Tool 40 and mieroseope 62 are movable as shown by arrows 109 and 110.
An adjustable tool 111 serves to reduee the original blank 10 to a desired diameter as a first step as deseribed. The surfaee93 may be maehined slightly rounded by appropriate shaped tools 40,45.
This applieation is a division of eo-pending Canadian Patent Applieation Serial No. 210,694, filed on Oetober 3, 1974.
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::
. ' :
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Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A contact lens lathe for manufacturing a contact lens from a lens blank, said machine comprising a lens blank support rotatable about an axis passing through the blank support, a first material removal tool mounted on a radius arm and arranged to traverse said support in an arc about an axis to form a first curved lens surface on a blank held by said support, and a second material removal tool arranged to be movable radially of the support into engagement with the blank so as to machine a generally frusto-conical peripheral portion of substantially uniform curved surface a peripheral portion of substantially uniform circumferential thickness, said support and said tools being arranged so that the machining movements of both tools may be effected without removing such blank from said support.
2. A lathe according to claim 1, in which a further tool is arranged so as to be traversable in an arc about an axis, the further tool being positioned to machine a circum-ferential edge on the blank after the or each traversal of the first tool.
3. A lathe according to claim 2, in which the further tool is mounted on the same radius arm as the first tool.
4. A contact lens lathe for manufacturing a contact lens from a contact lens blank, said machine comprising a lens blank support rotatable about an axis passing through the blank support, a radius arm having mounted thereon a first material removing tool and a second material removing tool, said radius arm being traversable in an arc about an axis and adapted to permit said first tool to contact said lens blank and machine a curved lens surface thereon, and to permit said second tool thereafter contact said blank and machine a circumferential edge surface thereon without removing the blank from the support, and a third material removing tool adapted to advance transversely of the axis of rotation of the blank support and to form a generally frusto-conical surface on the blank at its periphery.
5. A lathe according to claim 1, 2 or 3, including a viewing device arranged to view and determine a position on the crown of the machined first curved lens surface on such blank through the body of the blank in a direction perpendicular to the lens axis, a gauge to indicate such determined position and a further material removal tool settable in accordance with said determined position for traversal of said support to machine a second curved lens surface opposite to said first curved lens surface.
6. A lathe according to claim 4, including a viewing device arranged to view and determine a position on the crown of the machined first curved lens surface on such blank through the body of the blank in a direction perpen-dicular to the lens axis, a gauge to indicate such determined position and a further material removal tool settable in accordance with said determined position for traversal of said support to machine a second curved lens surface opposite to said first curved lens surface.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB4677573A GB1488001A (en) | 1973-10-06 | 1973-10-06 | Contact lenses |
| CA210,694A CA1028881A (en) | 1973-10-06 | 1974-10-03 | Manufacture of contact lenses |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1049818A true CA1049818A (en) | 1979-03-06 |
Family
ID=25667710
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA295,342A Expired CA1049818A (en) | 1973-10-06 | 1978-01-20 | Apparatus for the manufacture of contact lenses |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1049818A (en) |
-
1978
- 1978-01-20 CA CA295,342A patent/CA1049818A/en not_active Expired
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