LU87465A1 - METHODS AND APPARATUS FOR MANUFACTURING CAST OR MOLDED OBJECTS, IN PARTICULAR CORRECTIVE GLASSES - Google Patents

Description

7 ζ g * GRAND DUCHY OF LUXEMBOURG

/ * t V J

Dear Minister * of March 2, 1989________ JayC of Economy and the Middle Classes

jjiçJW Intellectual Property Service Title issues ...................................... LUXEMBOURG

Invention Patent Application ____________________________________________ (1) I. Request îâ-fiQfiiâ £ â_ ^ ltex-JŒLKINGIOKJiaS10EIG2ÆE-HOIJBÏN6ST-Sil ^ --- (2) 2420 Sand Hill Road, Menlo gark ^ -Californla 9402S- | EtatS "-URis - d1 America), represented by_MQnsleur_ Jacques., From Mnysar__________________________ acting as agent________________________________________________________________________ (3) deposits! Nt) this dayfrom ^ ^ ______________________________________________ (4) at 15 ._____________ ..... hours, at the Ministry of 'Économie et des Classes Moyennes, in Luxembourg: 1. this request for obtaining a patent for an invention concerning: "Processes and apparatus for the production of cast or_______________ (5) molded objects, in particular corrective lenses." .................................................. ...................................

2. the description in ... French __________________________________________________ of the invention in triplicate; 3. .............................. 3 ................. .................. drawing boards, in triplicate; 4. the receipt of the taxes paid to the Registration Office in Luxembourg, on March 1..QÇ ....... 19 8 9___________; 5. the delegation of power, dated ......................................... .................................................. ....... the.......................................... ..........................................—; 6. the successor document (authorization); declares! nt) assuming responsibility for this declaration, that the inventor (s) is (are): (6) claims (s) for the above patent application the priority of one (or more) application (s) s) from (7) .................................. M®.Y®..1r.® .................................................. .................................. deposited (s ^ S (8) in..United States.ni on (9) ......... 2 ...... March ...... 1988 ......... (No ........ 163.308). .................................................. .................................................. ........

236HHtPqsQ ..and ....... on ....... 3 ....... March ...... 1988 ........ (Νο. ".-. .16.3 .... 7-7 · 1 ·) __________________________________________________ — ............................

in the name of (il) iJjtoxsafciaur ........................................... .................................................. .................................................. ................................................

elect) domicile for him / her and, if designated, for his / her representative, in Luxembourg__________________________________________________ 35, boulevard ...... Royal ..................... .................................................. .................................................. .................................................. ............................................ (12) requests (nt ) the issuance of an invention patent for the subject described and represented in the abovementioned appendices, _ ^ averâjohrnement of this issuance to ..................... ....... ........................ LL .................. .................................................. .......................... ........................ ......................month. (13)

The depositor at / agent: ............................................ .................................................. .................................................. .................................................. .................................................. ....................... (14) \. V yV V V) \ l l) 4 · Deposit Report

The abovementioned request for a brief declaration was filed with the Ministry of the Economy and the Middle Classes, Service de ra Intellectual Property ^^ 'CQxembourg, dated: 2 Mar S 1989 -Ifl'. ·.

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/ J * "Λ« · «« * \ "0 *: ^ \% \. Pr. The Minister of Economy and the Middle Classes, to .................................... ..... hours ψ; ξ J? i p. d.

% 3 j? / The head of the intellectual property department, ¥ v ’'-v.- ·' # S? · V * ... · ***? ·> ,? · ........ · 'A 68007 * * · ί "j" \ i' y

EXPLANATION OF THE FORM

(1) if applicable "Application for a certificate of addition to the main patent, to the main patent application No ............ of .......... .. ”- (2) enter the surname, first name, profession, address of the applicant, when the latter is an individual or company name, legal form, address of the head office, when the applicant is a legal person - (3) enter the last name, first name, address of the professional representative, industrial property attorney, with special powers, if applicable: "represented by ............ acting as representative "s, - (4) date of filing in full - (5) title of the invention - (6) enter the names, first names, addresses of the inventors or the indication" (see) separate designation (will follow) ”, when the designation / dd * gnation is or will be made in a separate document, or the indication "not to mention", when the inventor signs or signs a document of non-mention to be attached to a designation f / / séoarée nrresentâ mi future - (7) patent, cert at addition, utility model, hr ^ ver t "nrnniSen rnRF.V nrnferrîivi intr" mnrinnnie ΙΡΓΓΠ - ίίΜ Ftnt rinn "Ipnnel lenremierriénnt has been rented; , .- 89 / B.52.805

CLAIM OF PRIORITY

of the patent application / dîtcmaksdSKibJikiiôi XBïi In the United States of America

Of March 2, 1988 (No. 163.308) and • of March 3, 1988 (No. 163.771) Brief Description filed in support of a request for

PATENT

at

Luxembourg on behalf of: pilkington visioncare holdings, inc.

Menlo Park, California 94025 (United States of America) for: π processes and apparatus for making cast or molded objects, including corrective lenses. "* ·" * "Μ 5

Processes and apparatus for manufacturing cast or molded objects, including corrective lenses

The present invention relates to methods and apparatuses for the production of castings or objects. molded, and in particular corrective lenses.

In the field of the production of ophthalmic lenses and the like, there is great interest in the development of simple and inexpensive manufacturing methods, yielding quality glasses requiring only a reduced or even non-existent finish after manufacturing. To this end, development efforts have concentrated on the casting and molding of glasses from thermoplastic and thermosetting materials and from merisable poly-20 materials, given the economies of scale and the possibilities of reduction in handling. and labor costs during these processes.

In casting and molding processes generally, the molds of a front surface and a rear surface are used so that they give the plastic optical surfaces suitable for the desired ophthalmic correction. In casting processes in general, the molds are fixed to each other by a packing or the like, with the desired spacing, and a liquid casting material is introduced into the cavity delimited by the molds and can then polymerize and harden into a glass. A primordial factor is constituted by the lining, and a very large number of linings are required, allowing cooperation and sealing with a large number of different optical surfaces of various molds, and also delimiting the desired spacing of the molds (and the glass thickness). Thus, the investments necessary for the linings and their tools as well as for the molds for forming the optical surfaces used in the casting process are very important.

In molding processes generally, more robust molds are used for the compression of a moldable material in a closed mold cavity, with the formation of optical surface patterns on the material when it hardens by a thermal process. or chemical. In general, an excess of molding material must be introduced into the cavity so that it allows displacement of the molds with compression, and a device must allow the excess material to be evacuated from the cavity and the formation material passage channels. Furthermore, as in the casting process, the molds must be pushed together, with the proper spacing, so that the glass has the desired thickness. The quantity of the molding material, the evacuation of excess material and the final thickness of the glass are related factors which require precise adjustment of the process for the production of high quality glasses for ophthalmic applications.

It is obvious that a primordial factor for the molding of glasses is constituted by the molding members themselves. Generally, a large number of molds of the front and rear surfaces should be available, each having an original characteristic of optical surface formation. According to a particular ophthalmic prescription, molding members suitable for the front surface and for the rear surface are chosen, an optimal thickness of glass is calculated for the two molds chosen, and a lining or the like. is selected or manufactured in such a way that the molds are fixed to each other and delimit the molding cavity. The cavity is then filled with a glass composition which is hardened or polymerized by heat, radiation or chemical action, and the finished glass is removed from the assembly.

The method indicated above requires a very large number of molds for the front and rear surfaces, depending on the hundreds of thousands of ophthalmic prescriptions which are commonly required. In addition, a large number of linings is necessary in this opera-tion, since the linings must form a tight seal with various curved edge configurations of the molding members, and the thickness of the glasses must be determined by the spacing * of the molding members provided by the linings. In this regard, the space-ment of the molds is generally measured between the optical surfaces with regard to the shaping of the molding members. It is essential that the spacing of the molds is greater than a predetermined minimum value, both for obtaining a glass of sufficient thickness and mechanical strength, and so that the molds do not crush and do not not destroy each other.

The large number of molding members and fittings which must be kept in stock for the implementation of the method described above, require considerable investments which are difficult to recoup by commercial sales. Consequently, it has been necessary in the prior art to simplify the process by reducing the number of elements kept in stock. The most obvious simplification is the molding of glasses having the desired front surface and a reference rear surface (or vice versa) which can be polished into the desired final glass in an optical dispensing laboratory or the like. This tactic introduces a cost of labor after manufacture and requires experienced personnel for the production of high quality glasses. Furthermore, it is not an improvement of the molding technology of the prior art but rather an expedient intended to make this technology commercially usable. There is clearly a need for a molding methodology which reduces the number of molding elements while allowing the fulfillment of the large number of common ophthalmic prescriptions.

• 1 · »4

The present invention relates · generally - a method and an apparatus for molding or pouring ophthalmic glasses or the like. The important features of the invention are the provision of a simplified method and apparatus automatically determining the appropriate amount of a pouring composition or ’. molding remaining in the finished glass and which also determines the spacing of the casting or molding molds and thus the thickness of the finished glass.

The apparatus comprises several molds intended for front and rear surfaces, having different optical shaping surfaces and identical peripheral configurations at their edges. In the compression molding process, any pair of front and rear surface molds is sealingly and slidably housed in the bore of the molding apparatus. At least one of the two molds has at least one pouring channel formed at its peripheral edge parallel to the axis of the bore between the optical shaping surface and a location adjacent to the opposite external mold surface . The pouring channel is a vent device allowing the evacuation of the excess molding composition from the molding cavity when the molds are brought together. When the mold having the runner is fully inserted into the bore, the opening of the runner to the outside is closed by the surface of the bore so that the evacuation effect is completed and a predetermined amount of the molding material is retained in the molding cavity. The molding material is then solidified by thermal or chemical reaction and forms the finished glass. Thus, the invention allows an intrinsic adjustment of the thickness · of the molded part, with also positive evacuation of the excess of the molding material.

During the casting process, the molds are partially introduced into the bore of a casting apparatus so that they slide tightly and the pouring channel constitutes an injection channel allowing 5 • 1 * ft both the introduction of the casting composition into the cavity. The molds are pushed towards each other in the bore, the pouring channel being first used for the evacuation of the excess of the pouring composition and of the gas from the pouring cavity. Maximum introduction into the bore causes the opening of the pouring channel * to be sealed against the exterior by the wall of the bore, so that the evacuation effect is completed and a predetermined amount of the pouring material is kept in the cavity. The material is then polymerized or hardened by a thermal or chemical reaction so that the finished glass is formed. The invention therefore allows intrinsic adjustment of the thickness of the casting part, while allowing easy filling of the casting cavity and evacuation of excess material and gas from the cavity.

The present invention also relates to a method for producing the molding elements and in particular glass molding elements. An important feature of the invention is that it reduces the number of molds, compared to conventional molding technology, necessary for the production of the same variety of ophthalmic lenses. In addition, in molding processes requiring fittings or the like for fixing two molding members to each other so that they delimit the molding cavity, the number and variety of fittings required are reduced by very importantly.

The method of producing a molding apparatus, intended in particular for molding glasses and the like, comprises delimiting a nominal mold reference curve disposed between two mold members having curved and smooth surfaces placed opposite so that 'they define between them a molding cavity. It is possible to determine a single value of the reference curve so that all the glasses of an example of nominal family are intersected by this imaginary surface without interference, that is, that is, for all »positive vergence glasses, we have front curvature> reference curvature £ rear curvature and for all negative vergence glasses, we have 5 rear curvature £ reference curvature £ front curvature This phenomenon is the result of the optical and physical uniformity of the characteristics of the face and of the human eye, and it has been described in the prior art.

Several concave and convex molding members 10 are produced, all having different curvatures from their molding surface and an identical spacing between the respective curved surface and the nominal reference curve, measured from the point of greatest approximation of the curved surface. and the reference curve (that is to say between the center of a diverging lens and the reference curve or between the edge of a converging lens and the reference curve).

Any pair of concave and convex molding surfaces have the same spacing from the reference curve and thus from each other so that, for example, a universal pad can be used for holding of two paired convex and concave molding members with precise spacing, whatever the curvature of the molding surfaces. Thus, any glass formed by implementing the method according to the invention comprises two indivisible parts, a front part going from the reference curve to the front surface and a rear part going from the reference surface to the rear surface.

Other characteristics and advantages of the invention will be better understood on reading the following description of embodiments, made with reference to the accompanying drawings in which: Figure 1 is an exploded perspective of a example of a glass molding apparatus according to the invention; Figure 2 is a plan view of a mold for molding an ophthalmic lens, made according to the invention; »\« »'7 la. Figure 3 is an enlarged partial side elevation of the mold of Figure 2, showing the pouring channel formed at its peripheral edge; Figures 4 to 6 are successive sections in elevation illustrating a glass molding operation according to the invention; Figures 7 to 9 are successive sections in elevation illustrating the casting method <3rd glass according 1'invention; FIG. 10 is a perspective view of a glass formed by implementing the invention, showing the pouring jet formed in the pouring channel before its removal; FIG. 11 is a section in elevation of a glass molding assembly, produced by implementing the method for producing parametric molds according to the invention and using a packing sleeve for the connection of the molding members in a casting assembly; and FIG. 12 is a sectional elevation of a glass molding assembly implementing the method of producing a parametric mold according to the invention, and using compression molding elements for forming a glass .

The present invention relates generally to a method and apparatus for making ophthalmic lenses and the like, by molding and casting techniques. As indicated in the figures there 3, the apparatus intended for the implementation of a molding process according to the invention comprises a cylindrical member 11 having a bore 12 disposed axially. A mold 13 forming a front surface and a mold 14 forming a rear surface are also arranged so that each of them has optical shaping surfaces whose configuration allows the formation of a complementary optical surface and the delimitation of the optical properties of the glass to be manufactured. As is known in the art, a large number of molds 13 and 14 are arranged, each having "8. * "Fr original surfaces of optical shaping so that the invention allows the production of various ophthalmic lenses covering the whole range of current correction prescriptions. A characteristic common to all the molds of the front and rear surfaces is that their peripheral edges 16 and 17 have dimensions and configuration allowing them to slide in the bore 12 and their sealed cooperation out of respect 1 for tight tolerances.

An important characteristic of the present invention is the presence of at least one pouring channel 18 formed in part of the peripheral edge of at least one of the molds 13 and 14. In the embodiment of FIGS. 1 to 3 , two casting channels 18 are formed in the part 16 of the edge of the mold 13 of the front surface. (Any mold can have the runners and the number of runners is not essential). The runners are oriented parallel to the axis of the cylindrical peripheral edge 16 and are diametrically opposite. The casting channels 18 are narrow and each subtend an angle of a few degrees around the cylindrical axis of the mold. Each channel intersects the optical shaping surface at a first end and joins a location adjacent to the opposite external surface 21 of the mold as best shown in Figure 3. The end of the channel and the adjacent external surface 21 of the mold define between them an intermediate lip19.

The apparatus of Figures 1 to 3 is used in a glass molding process illustrated schematically successively in Figures 4 to 6. As shown in Figure 4, a mold 13 of the front surface and a mold 14 of the rear surface are placed opposite one another in the bore 12 of the cylindrical member 11 and delimit a closed glass molding cavity. A charge of glass molding material 22 is placed in the cavity between the molds. The molding material can be injected into the cavity. Alternatively, the molding material can be s * -9

Jk loaded into the cavity after one of the molds has been placed in the bore and before the other is placed there. In any case, generally an amount of the molding material should be used which is greater than the amount of material which forms the finished glass so that subsequent compression of the molds ensures the formation of the optical forming surfaces in the material with the realization of the desired molded optical surfaces.

After the different molding elements and materials have been assembled as shown in FIG. 4, the molds 13 and 14 are pressed against each other by compression, with application of sufficient pressure to the molding material 22. This material flows under the action of this pressure and takes the form of the optical forming surfaces 15 and also flows towards the outside of the pouring channels 18 as shown in FIG. 5. The pouring channels 18 constitute vent devices allowing the excess of the molding material 22 to be evacuated, the displacement of the molding material from the cavity also allowing the molds to penetrate further into the bore while approaching and to give approximately 1 spacing corresponding to the thickness desired for the finished glass. When the mold 13 in particular is introduced into the bore a sufficient distance for the external surface 21 to approach the end of the bore, the lip 19 of each channel 18 penetrates into the bore 12. At this point at the time of the introduction of the molds, the external openings of the channels 18 are closed in a leaktight manner by the wall of the bore 12, and no additional evacuation can be carried out by the casting channels. An additional compressive force applied to the molds does not allow their greater approximation and simply ensures the application of greater pressure to the molding material. When the molding material 35 has solidified (for example by cooling to a temperature below the glass transition temperature, by catalytic reaction or the like), the molds 10 are removed from the bore and the finished glass is separated from the molds .

It should be noted that the penetration depth of the mold 13 is adjusted by the length of the neck channels 18, and that the depth of introduction of the mold determines the thickness of the finished lens. Furthermore, the insertion depth of the mold is relatively independent of the initial amount of molding material placed in the molding cavity since the excess material is removed from the cavity. Thus, the apparatus implements a process ensuring the production of finished glass of uniform thickness in a self-regulating manner without a precise adjustment of the initial quantity of the molding material being necessary.

15 -, The method described above is suitable for molding thermoplastic materials such as polycarbonates or thermosetting materials or other materials which can be polymerized or hardened by application of pressure, under the action of heat or by chi reaction -20 mique, inside the mold cavity.

A slight variant can be used for pouring ophthalmic lenses using casting compositions known in the art such as the composition "CR39" and its equivalents. As shown in FIGS. 7 to 9, the mold 13 of the front surface and the mold 14 of the rear surface are arranged and produced as described above, with the casting channels 18 formed at the peripheral edge of one of the molds at the less. The molds are housed in the cylindrical bore 34 of a cylin-30 drique tubular sleeve 33 and cooperate by sliding in leaktight manner with the wall of the bore. The sleeve 33 has a thinner side wall than the cylindrical member 11 since very low pressure is used in the casting process.

Initially, the molds 13 and 14 are partially introduced into the bore 34, the casting channels 18 leaving the bore 34. The casting channels can be used. as input channel for. The introduction of a charge of a viscous liquid material 32 for casting into the cavity delimited by the molds and the wall of the bore as shown in FIG. 7. After a sufficient quantity of material of casting has been placed in the cavity, the molds are pushed back into the bore 34 and brought close to each other, using a relatively low force applied to the molds. This action1 causes a decrease in the pouring cavity, with initially evacuating unwanted air or other gases from the cavity, then evacuating the excess of the pouring material so that it is evacuated through the channels 18 as shown in Figure 8.

When the molds are completely introduced into the bore 34, the casting channels 18 cooperate in leaktight manner with the wall of the bore 34 as indicated in the previous embodiment. Then, no additional quantity of the pouring material can be removed from the cavity as shown in Figure 9, and the thickness of the glass to be formed is determined by the amount of the pouring material remaining in the cavity. A low force (exerted by a spring device or the like, in a manner known in the art) is then applied to the molds so that these are kept applied to the casting material when the latter undergoes polymerization and solidification, under the action of heat and / or by chemical reaction. When the glass has been fully formed, the molds are removed from the sleeve 33 and the finished lens is separated from the molds.

As noted with reference to the above embodiment, the depth of introduction of the mold 13 is controlled by the length of the pouring channels 18, and the depth of introduction of the mold determines the thickness of the finished glass. In addition, the insertion depth of the mold 35 is relatively independent of the initial quantity of the casting material placed in the cavity since the excess of the material is evacuated from the cavity. The device therefore allows i „1. , · 12 thus the implementation of a manufacturing process. of * y> finished glass of uniform thickness of self-regulating type without ‘that a precise adjustment of the initial quantity of the casting material is necessary.

j 5 The glass 36 which is formed by the casting or j molding process described above in the appearance indicated in j in FIG. 10. Several casting jets 37 protrude from the edge: peripheral of the glass, due to a jet ' by pouring channel formed in the molds. The pouring jets 37 are narrow and fragile and can be easily removed from the glass by cutting or manually by separation by breaking at their base. The casting jets can also form a convenient "handle" facilitating manual transfer or "| by machine and handling of the finished glass. Since 3 1 15 since all ophthalmic lenses are machined to their | edge so that they fit in the spectacle frames, j the pouring jets 37 are removed from the finished lens and do not | show no discomfort in the final product.

| The present invention also relates to a method of | 20 production of molding elements and in particular of elé! glass molding elements. The method relates to a system for molding glasses allowing the satisfaction of a product! significant portion of the most ophthalmic prescriptions ”; common, using molds in numbers much lower than that required in other techniques! for molding glasses.

! We refer to Figure 11; the invention highlights; works several molds intended for molding the front surface, j represented by the mold 111 having a concave surface 112 ij 30 of optical molding, and several molds intended for molding a rear surface, represented by the mold 113 which has a convex surface 114 optical molding. The molding surfaces 112 and 114 can be produced by rectification and polishing of a glassy or metallic material, or by electrodeposition on previously formed optical surfaces, these two techniques being well known. In the embodiment of FIG. 11, the two molds have a generally cylindrical shape, the axes, of the cylinders generally passing through the central parts of them; Respective molding surfaces. The mold 111 has a flange 116 projecting radially outward from the mold and placed axially at a certain distance from the surface 112, and the mold 113 has a flange 114 also protruding radially outside the mold and placed at a certain axial distance from the surface 1141 The flanges 116 and 117 have annular surfaces 118 and 119 respectively which are placed at a distance and facing each other.

The invention also relates to a sleeve or a lining! ture 121 intended to connect the two molds in one! casting set. The sleeve has a general cylindrical configuration, its diameter being sufficient to ensure leaktight cooperation at the peripheral surfaces of the two molds, the ends of the sleeve 121 being in abutment against the flanges 116 and 117. The length of the sleeve , between the two flanges 116 and 117, is generally constant and it is the same for any combination of molds 111 and 113.

An important feature of the invention is the establishment of a reference curve 122 arranged between the molding surfaces 112 and 114. The reference curve represents the plane nominal curve of the glasses produced by this process, that is to say - say that a flat glass has its front and rear surfaces which are parallel to the reference curve. The reference curve 122 is also used to establish the proper spacing of the molds and the molding surfaces 112 and 114. For the various molds 111 and 113, the distance between the surface 112 and the reference curve 122 is fixed and is always the same, and the distance between the surface 114 and the reference curve 122 is also fixed and always the same. The distance between the surfaces 112 or 114 and the reference curve is measured from the point of greatest approximation of the molding surface and the reference curve. This factor determines either the center of a diverging lens, or the edge of a converging lens, molded according to the invention, having a fixed thickness, throughout the range of ophthalmic prescriptions.

It is important to note that the flange 116 is at a predetermined axial distance from the surface 112, and the flange 117 is itself placed at a predetermined axial distance from the surface 114. Thus, the distance X between. the surface 118 of the flange and the reference curve and the distance Y between the surface 119 of the flange 10 and the reference curve are determined in the casting assembly by the sleeve, whatever the molds chosen for the formation of a special glass.

During the implementation of the invention described with reference to FIG. 11, the molds 111 and 113 are selected according to the ophthalmic prescription, and a sleeve 121 is chosen with a length which ensures the placing of the surfaces 112 and 114 for optical shaping at the predetermined fixed distance from the reference curve. A casting composition is then introduced into the cavity 20 delimited by the molding surfaces and the internal surface of the sleeve, by injection or the like, and the composition is hardened or polymerized so that it forms the finished glass. The sleeve is then removed and the glass is separated from the molds. These can then be cleaned and stored before reuse.

Another embodiment of the present invention, illustrated by FIG. 12, is intended for the formation of glasses by compression molding by applying the principles described with reference to embodiment 30 of FIG. 11. Two molds 111 ′ and 113 ′ have optical shaping surfaces 112 ′ and 114 ′ as described above. In this embodiment, the molds have smooth peripheral walls and have dimensions such that they can slide in the bore 132 of a cylindrical sleeve 131. As indicated above, the molding surfaces 112 'and 114' are placed at a fixed constant distance from a reference curve 121 '. The mold 111 'I. 15! '· J is fixed to a piston 133 aligned coaxially on the sleeve j 131, and the mold 113 is fixed to a coaxial piston 134. Two .3' ·] piston stops 136 and 137 are also intended to limit * displacement from the respective pistons 133 and 134 towards the i '| 5 reference curve 121 ', at distances X1 and Y'. These j distances X 'and Y' are calculated so that the molding surfaces 112 'and 114' can be displaced by the respective pistons towards the single reference curve- • | up to the distance limit fixed by the curve of | 10 reference.

] In the embodiment of Figure 12, two molds 114 and 113 'are chosen according to the prescription ·] ophthalmic, and the molds are mounted on the respective pistons]. A charge of a glass-forming material is introduced into the bore 132 between the molds, and the molds are brought together by the pistons so that the material is compressed and molded to the shape determined by! surfaces 112 ’and 114’. The material is then solidified i; by hardening, polymerization, cooling or the like, depending on the composition and properties of the material. The pistons are then removed and the finished glass j is separated from the molds. These can then be removed, cleaned and stored before further use.

In the process illustrated in FIG. 12, the material intended to form the glass can be injected into the cavity inside the cylinder, the molds being introduced up to the limit determined by the stops 136 and 137, as in known injection molding techniques. Likewise, a hybrid glass-forming technique using injection of the material and then compression of the molds can also be used in the context of the invention.

It should be noted that the principle of runner molds is well suited for adjusting the depth of insertion of a mold into a bore as described previously, and the runner molds are an advantageous device for the determination of the predetermined distances 16 min between the molding surfaces and the curve.

reference. The invention combines the principles of the use of · several pour channel molds having a family of parametric molding surfaces, in a device for manufacturing glasses.

The method described with reference to FIGS. 11 and 12, concerning the parametric production of the molds, not only gives glasses of uniform thickness but also minimizes the number of molds necessary for the manufacture of a whole range of glasses with several focal points , either in the form of glasses in stock (without cylindrical vergence), or in the form of finished glasses having a cylindrical vergence. For example, the following table allows the comparison of a parametric production method with a glass molding system of the prior art, during the manufacture of 75 mm glasses formed from "CR39", in a range of vergences between - 4.00 δ and +4.00 δ. The powers vary in fractions from 0.25 δ up to +3.00 δ, and the cylindrical vergences cor-20 respond to variations from 0.25 δ up to -2.00 δ.

Number of items required

Simple vision Several homes without vergence with cylindrical cylindrical vergence

Parametric front surfaces 5 65 65

Parametric 2Q rear surfaces 153 17 153 TOTAL 158 82 218

Front surfaces "CR39" 33 429 429

Rear surfaces "CR39" 63 7 63 oo TOTAL 96 436 492 I.

I. . . .

1 '-' I.

! . 17 t

The process for making. parametric molds> j thus requires 458 molds for the production of the whole | range of glasses whereas the process of the prior art requires 1024 molds. Thus, it appears that the \ ‘| 5 present invention allows significant savings not - "p only in investment cost necessary for the provision of molds but also for 1 · 'maintenance of a very large number of molds. In addition, the invention prevents contact between the molds during the molding operation, S 10 this operation occasionally appearing in the known molding systems and causing destruction of the molds.

Of course, various modifications can be made by those skilled in the art to the methods and apparatuses which have just been described only by way of nonlimiting examples without departing from the scope of the invention.

Claims (14)

1. Process for manufacturing molded objects, character- | laughed at in that it includes the following steps:! forming a bore (12) in a molding apparatus, arranging a pair of molds (13, 14) housed in the bore so that they can slide therein tightly, one of the at least molds having an object-forming surface, an opposite external surface and a peripheral edge surface intended to be in leaktight and sliding contact with the bore, the formation of at least one pouring channel (18 ) in the surface of the peripheral edge, this pouring channel starting from an intersection with the object-forming surface 15 and joining a point adjacent to the external surface of the mold ,. the partial introduction of the molds (13, 14) into the bore, one opposite the other, with a charge of a fluid molding material placed between them, the object-forming surface being in contact with the molding material, forcing the molds together so that the load of the molding material is compressed and the molding material flows and takes the configuration of the object-forming surface, the compression of the molding material also causing the flow of excess molding material into the casting channel and its evacuation through this channel, the greater introduction of the mold into the bore so that the casting channel is tightly closed and the evacuation by this pouring channel is interrupted, and the solidification of the molding material so that a finished object is formed. 2. Method according to claim 1, characterized in that it further comprises the formation of two pouring channels (18) in the mold (13). . 19!>, »*» 3. Method according to claim 1, characterized in that the object is an optical glass, and the object-forming surface of the mold is an optical forming surface. 4. Method according to claim 1, characterized in that the pouring channel (18) at least is generally parallel to the axis of the bore. 5. Apparatus for manufacturing molded objects, characterized in that it comprises a bore (12) formed in a molding apparatus, a pair of molds (13, 14) intended to penetrate into the bore so that they cooperate sealingly by sliding with it, at least one of the molds having an object-forming surface, an opposite external surface, and a surface of a peripheral edge intended to cooperate sealingly by sliding with the bore, at least one pouring channel (18) formed in the surface of the peripheral edge, the pouring channel having an internal end intersecting the object-forming surface and being directed towards the external end, close to but not intersecting the outer surface of the mold, and a device for bringing the molds together in the bore so that a molding material present therein is compressed and the excess of the mold material molding is discharged through the runner at least. 6. Apparatus according to claim 5, characterized in that the pouring channel (18) at least is generally parallel to the axis of the bore. 7. A method of manufacturing cast objects, characterized in that it comprises the following steps: the formation of a bore (12) in a casting apparatus, the formation of two casting molds (13, 14) which are housed in the bore so that they can slide there by sealed cooperation, at least one of the molds! \ * ··. ·; ; . '20 having a shaping surface, object, an opposite external surface and a peripheral edge surface which cooperate sealingly by sliding with the bore, forming at least one casting (18) into the peripheral edge surface, the pouring channel being disposed at an intersection with the object forming surface at a location adjacent to the external surface of the mold, the introduction of the molds partially into The bore opposite one another so that they delimit between them a pouring cavity, the injection of a load (22) of a flowable flow material through the pouring channel and into the pouring cavity, bringing the molds together so that the load of the pouring material is compressed and this material flows and takes the configuration of the object-forming surface, the compression of the pouring material 20 causing also the flow of excess pouring material and gas into the pouring channel and their evacuation by this channel, the introduction of the whole mold into the bore so that the pouring channel is closed in a sealed manner and that the evacuation is interrupted by this pouring channel, and the solidification casting material so that it forms a finished object. 8. Apparatus for manufacturing cast objects, characterized in that it comprises a bore (12) formed in a casting apparatus, two molds (13, 14) for casting which can be introduced into the bore with which they cooperate sealingly by sliding, at least one of the molds 35 having an object-forming surface, an opposite external surface and a peripheral edge surface arranged in leaktight cooperation by sliding with the bore, ij \ ^ * * - "i {'* a 5 * j * 21 s" 4! at least one pouring channel (18) formed in the sur- ΐ t face of the peripheral edge, the channel having one end: j internal intersecting the object-forming surface and | being directed towards an external end which is adjacent to 3 j 5 the external surface of the mold but which does not intersect this | surface, and - - j, a device intended to bring together the molds in the bore so that a casting material placed between them is compressed and that the excess of the casting material 1. is evacuated through at least the casting channel. 9. Method for manufacturing ophthalmic lenses,] characterized in that it comprises the following stages: la | provision of a first set of molds (13) for the molding of front surfaces and having concave surfaces of optical shaping, provision of a second set of molds (14) ) for molding rear surfaces having convex optical shaping surfaces, selecting a front surface mold (13) and a rear surface mold (14) from; ; 20 sets of molds, the delimitation of a reference curve! molding rence (122), the arrangement of the selected molds; opposite in a molding assembly, the concave optical shaping surface being at a first fixed distance from the molding reference surface and the convex optical shaping surface being at a second fixed distance; of the molding reference curve, then molding a! : glass between the molds. • 10. Method according to claim 9, characterized in that the first distance fixes to the reference curve! 30 (122) and the second distance fixed to the reference curve; . are both constant regardless of the molds among the first and second set of molds. 11. Method according to claim 10, characterized in that the reference curve is placed between the opposite molds (111, 113). 12. Method according to claim 11, characterized in that it comprises the provision of a sleeve (121); . '22s intended. à · connect the molds chosen in a set of k 4 -; casting of glass, the mold maintaining the first and the second fixed distance from the molds to the reference curve. 13. The method of claim 11, characterized in that it further comprises the formation of a bore (132) intended to accommodate the selected molds (111 ', 113') * so that they can move by sliding in a compression molding assembly. 14. A method of manufacturing ophthalmic lenses, characterized in that it comprises the following steps: the provision of a first set of molds (111 ') for molding front surfaces having concave surfaces for optical shaping , providing a second set of molds (113 ′) for molding rear surfaces having convex surfaces for placing! form, optics, the selection of a mold (111 ') for molding a front surface and a mold (113') for molding a [rear surface among the sets of molds, the delimitation of 'a molding reference curve (121'), the arrangement of the molds chosen opposite in a set of i: molding, the concave surface of optical shaping being}: at a first fixed distance from the curve of molding reference and the convex optical shaping surface being at a second fixed distance from the molding reference curve, at least one of the chosen molds having a peripheral edge surface and an opposite external surface, the realization at least one runner in the peripheral edge surface, the runner being disposed between an intersection with the respective optical shaping surface and a location adjacent to the outer surface, providing a bore (132) intended to house the molds chosen from the assembly molding, the partial introduction of the molds into the bore opposite one another with a charge of a fluid molding material placed between them, the contact surface! : c * * ‘'I · * | · 23 j shape being in abutment against the molding material, 5 c S the approximation of the molds so that the load 4 * 1 of the molding material is compressed and that the material ". the molding flows and takes the configuration of the shaping surface, the compression of the molding material, also causing the excess of the molding material to flow through the runner and its discharge through this channel, the introduction of the whole mold into the bore 10 so that the pouring channel is sealed and the evacuation ensured by the casting channel 8] is stopped, and j solidifying the molding material so that a finished glass is formed. i 'i to i t