Ophthalmic lens forming shell and process for manufacturing such a forming shell

Abstract

The ophthalmic lens forming shell (30) has two main surfaces (31, 32) and an edge surface (33) surrounding the main surfaces. The first of the main surfaces is adapted to face another forming shell during the formation of the ophthalmic lens. Further, the ophthalmic lens forming shell has: · a flat surface (34) extending along the outer edge of the first main surface; and · a first chamfer (36) extending along the outer edge of the flat surface between the flat surface and the edge surface.

Description

Technical Field

[0001] The present invention generally relates to the field of glasses.

[0002] Specifically, the present invention relates to a molding shell suitable for and intended to form an ophthalmic lens and having two main surfaces and an edge surface surrounding the main surfaces, wherein the first of the main surfaces is adapted to face another molding shell for forming an ophthalmic lens.

Background Art

[0003] Conventional molds for forming ophthalmic lenses have two molding shells around which an annular closing member that defines a molding cavity by these shells is disposed.

[0004] The two molding shells are generally made of a transparent material, while the closing member is made of a tape.

[0005] The main function of the tape is to close the space between the molding shells so as to maintain the monomer between these shells when the mold assembly is filled with the polymerized monomer.

[0006] The molding shells are usually manufactured by a computer numerical control device and polished in a polishing device.

[0007] Each molding shell has two main surfaces, the first of which is designed to generate the surface of the lens. Also, each shell has an edge surface located around these main surfaces.

[0008] The edge line of the first main surface disposed at the junction between this first main surface and the edge surface is circular or sharp around the main axis. However, its cross section (in the plane having this main axis) may become rounded due to the polishing tool, which generates a certain kind of chamfering.

[0009] This chamfered, rounded or sharp shape is not intentional, and its size is extremely uncontrollable and particularly very small.

[0010] The Applicant has observed that this rounded or sharp shape generates chips that minimize the life of the forming shell along the edge of this major surface.

[0011] The Applicant has also observed that it is important to provide a very specific size for the chamfer in order to facilitate the disassembly of the lens when the monomer is polymerized.

[0012] However, in practice, the control of the size of this chamfer is a difficult goal to achieve and this can make the forming shell very fragile. Summary of the Invention Means for Solving the Problems

[0013] In this context, the present invention provides a solution for the durability of the forming shell, which also improves the lens disassembly performance.

[0014] More specifically, the present invention has an ophthalmic lens forming shell defined in an introduction part, which - has a flat surface extending along the outer edge of the first major surface, and - has a first chamfer extending along the outer edge of the flat surface between the flat surface and the edge surface. has.

[0015] In other words, the Applicant has found a specific shape for machining around the first major surface in order to increase the durability of the forming shell without affecting its lens disassembly performance (i.e., without increasing the time required to form and disassemble the lens).

[0016] In addition, the applicant has also developed a machining process for generating this specific shape that allows for relatively good chamfer size consistency and relatively good mold edge quality, enabling a low scrap rate of the lens and good casting yield performance.

[0017] The formed shell obtained by using this process actually has a relatively large resistance force (and can be used twice as long as the formed shell currently in use), and has relatively few chips, thereby reducing the number of lenses to be discarded.

[0018] Other preferred features of the present invention are as follows. - The flat surface has a width equal to 0.5 mm with a tolerance of ±0.1 mm. - The edge surface extends around the central axis. - In each cross-section of the first chamfer in the plane passing through the central axis, the first chamfer is inclined at an angle of 40° with respect to the flat surface with a tolerance of ±5°. - The first chamfer has a width measured radially with respect to the central axis equal to 0.08 mm with a tolerance of ±0.05 mm. - The ophthalmic lens forming shell has a second chamfer disposed between the edge surface and the other main surface. - In each cross-section of the second chamfer in the plane passing through the central axis, the second chamfer is inclined at an angle of 45° with respect to the edge surface with a tolerance of ±5°. - The second chamfer has a width measured radially with respect to the central axis equal to 0.5 mm with a tolerance of +0.2 mm or -0.1 mm.

[0019] Furthermore, the present invention relates to a process for manufacturing an ophthalmic lens forming shell, which - Machining a raw piece to obtain a semi-finished molded shell having two main surfaces and an edge surface surrounding the main surfaces, wherein the first of the main surfaces is adapted to face another molding shell during the molding of an ophthalmic lens, and a preliminary chamfer is disposed between the edge surface and the first main surface; - Polishing, 〇 A flat surface extending along the outer edge of the first main surface, and 〇 A first chamfer extending along the outer edge of the flat surface between the flat surface and the edge surface; Polishing the preliminary chamfer and the edge surface to generate the flat surface and the first chamfer; and having.

[0020] Preferably, in the polishing step, a material thickness of at least 0.03 mm is removed from the edge surface and / or from the preliminary chamfer.

[0021] Preferably, the polishing step includes a first sub-step in which the preliminary chamfer is reduced and a flat surface appears, and a second sub-step in which the first chamfer is finished.

[0022] Preferably, at the end of the first sub-step, the flat surface has a width measured radially in relation to the central axis of the edge surface of 0.5 to 0.6 mm, and the first chamfer has a width equal to 0.13 mm with a tolerance of ±0.02 mm.

[0023] Preferably, at the end of the machining step, the preliminary chamfer is inclined at an angle of 40 degrees in relation to the edge surface with a tolerance of ±5 degrees.

[0024] Preferably, at the end of the machining step, the preliminary chamfer has a width measured radially in relation to the central axis of 0.8 mm with a tolerance of ±0.05 mm.

[0025] The following description, with reference to the accompanying drawings, which are given by way of non-limiting example, discloses what the invention consists of and the manner in which it may be reduced to practice.

[0026] The accompanying drawings are as follows.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0028] FIG. 1 shows a mold assembly 10.

[0029] This mold assembly 10 has two molding shells 20, 30 and an annular closing member 40 arranged around these shells.

[0030] Each molding shell 20, 30 has the shape of a thick transparent disk with two main surfaces 21, 22, 31, 32 and peripheral edge surfaces 23, 33.

[0031] The first main surfaces of the molding shells 20, 30 facing each other are referred to as "inner surfaces 21, 31". These inner surfaces are shaped to produce the main surfaces of an ophthalmic lens. One of these inner surfaces is convex and the other is concave.

[0032] The other main surfaces of the molding shells 20, 30, referred to as the outer surfaces 22, 32, can be planar (as shown in FIG. 1), or can exhibit different shapes (as shown in FIG. 2).

[0033] The peripheral edge surfaces 23, 33 of the molding shells 20, 30 here have the shape of a cylindrical rotation centered on the main axis A1.

[0034] The thickness of the peripheral edge surfaces 23, 33 is usually 3 millimeters to 6 millimeters.

[0035] The two edges of each peripheral edge surface 23, 33 have a circular shape.

[0036] The two molding shells 20, 30 are arranged in relation to each other in the molding process such that their inner surfaces 21, 31 face each other and their main axes A1 coincide and remain in that state.

[0037] The closing member 40 has the shape of a band wrapped and glued around at least a part of the peripheral edges of the two molding shells 20, 30.

[0038] This closing member maintains one molding shell at a predetermined distance from the other. Thus, the two molding shells 20, 30 and the closing member 40 together define a molding cavity 11 filled with a molding material (hereinafter referred to as a "monomer"), and this molding cavity 11 has a lens shape (with the unevenness reversed).

[0039] As a result, the inner surface of the closing member 40 presents two lateral portions glued onto the peripheral edge surfaces 23, 33 of the two molding shells 20, 30 and a central portion adapted to close the molding cavity.

[0040] Here, this closing member 40 has a length greater than the periphery of the peripheral edge surfaces 23, 33 of the respective molding shells 20, 30 in order to completely close the molding cavity 11 after this cavity is completely filled with the monomer.

[0041] Both molding shells 20, 30 are manufactured in the same manner so as to have similar characteristics. In the following, for the sake of clarity of explanation, only one of these molding shells 20, 30 will be described and represented in the figures.

[0042] This molding shell 30 has an internal main surface 31 that is concave.

[0043] The exact shape of the internal and external surfaces can be very diverse and will be omitted here. As shown in FIG. 2, it should only be noted here that this molding shell 30 has a certain thickness.

[0044] More specifically, the present invention relates to the shape of the area arranged at the joint between the internal main surface 31 and the peripheral edge surface 33 of the molding shell 30.

[0045] The shape of this area is actually important for ensuring good demolding of the lens and increasing the durability of the molding shell (since this area is subjected to strong stresses, it is often this area that requires replacement of the molding shell).

[0046] According to the present invention, as shown in FIGS. 3 and 4, the molding shell 30 has, within this area, - a flat surface 34 having one side that coincides with the outer edge line of the internal main surface 31, - a first chamfer 36 having one side that coincides with the outer edge line of the flat surface 34 and the other side that coincides with the inner edge line of the peripheral edge surface 33. and has.

[0047] Here, when the terms "inner" and "outer" mean a direction parallel to the main axis A1, it should be noted that the term "outer" means a direction that is radial in relation to this axis (the outer side is arranged in the direction opposite to this axis).

[0048] The flat surface 34 has a flat ring shape, and the first chamfer 36 has a truncated conical shape, and they extend between the inner main surface 31 and the peripheral edge surface 33. The first chamfer is arranged outside the flat surface 34 in relation to the main axis A1.

[0049] As shown in FIG. 3, the flat surface 34 extends in a plane perpendicular to the main axis A1 and has an annular shape with a constant width W3 centered on this main axis A1. As a result, both of its sides have a circular shape.

[0050] The width 3 measured radially in relation to the main axis A1 is preferably equal to 0.5 mm with a tolerance of ±0.1 mm.

[0051] As shown in FIG. 4 in a cross-section generated in a normal plane including the main axis A1, the first chamfer 36 is inclined at a constant angle α1 with respect to the flat surface 34 around all of the main axis A1.

[0052] This angle α1 is non-zero. It is preferably 40° with a tolerance of ±5°.

[0053] Also, the width W1 of this first chamfer 36 is also non-zero and remains constant around all of the main axis.

[0054] This width W1, measured radially in relation to the central axis A1, is preferably equal to 0.08 mm with a tolerance of ±0.05 mm.

[0055] In other words, the width W3 is more than three times larger than the width W1 and, preferably, more than five times larger than the width W1.

[0056] As shown in FIG. 3, on the other side of the peripheral edge surface 33, the forming shell 30 has a second chamfer 35 arranged between this edge surface 33 and the external main surface 32.

[0057] In each cross section generated in the plane containing the main axis A1, the second chamfer 35 is inclined in relation to the peripheral edge surface 33 by a non-zero angle α2, preferably 45°, with a tolerance of ±5°.

[0058] Also, the width W2 of this second chamfer 35 is also non-zero and remains constant in all directions around the main axis. Measured radially in relation to the central axis A1, this width W2 is equal to 0.5 mm, preferably with a tolerance of +0.2 mm or -0.1 mm.

[0059] The process of manufacturing the forming shell 30 is very special in that machining the exact flat surface 34 and the first chamfer 36 is extremely difficult.

[0060] For this purpose, this process has two main steps.

[0061] The first main step has a step of machining the raw piece so as to obtain a semi-finished forming shell 30' having only a preliminary chamfer 39, as shown in FIG. 5.

[0062] The second step has a step of polishing at least a part of this semi-finished forming shell 30' so as to obtain the above-described forming shell 30.

[0063] We can describe this process in more detail.

[0064] The raw fragment can have any shape, but its size is necessarily larger than that of the semi-finished formed shell 30' to be machined.

[0065] For example, this can have the shape of a thick disc of a certain thickness.

[0066] However, in a preferred embodiment, this raw fragment already has two main surfaces and edge surfaces presenting a shape similar to that of the above-mentioned formed shell 30. The main difference is that instead of having flat surfaces and a first chamfer, the raw fragment has rounded edges connecting the respective main surfaces and edge surfaces. This rounded edge has the shape of an arc of a circle with a radius of 2 mm in the cross-sectional plane.

[0067] The first step is preferably carried out by a CNC device so as to remove some material from the raw fragment in order to obtain the semi-finished formed shell 30'. This CNC device is preferably a ruining machine.

[0068] This is, for example, a Schaublin lathe (e.g., 302 Schaublin device).

[0069] In this first step, the edge surfaces are ground so as to reduce their diameter and to generate a preliminary chamfer 39.

[0070] As a result, at the end of the first step, as shown in FIG. 5, the semi-finished formed shell 30' has - two main surfaces 31, 32 (the reason for the reference numerals 31, 32 is that their shapes are similar to those of the main surfaces of the finished formed shell 30) and an edge surface 33' surrounding these main surfaces 31, 32, - a preliminary chamfer 39 arranged between the edge surface 33' and the first main surface 31, and.

[0071] The preliminary chamfer 39 has a truncated conical shape extending between the outer edge of the inner main surface 31 and the peripheral edge surface 33' (having rotational symmetry about the main axis A1).

[0072] In each cross-section generated in a plane containing the main axis A1, the preliminary chamfer 39 is inclined with respect to the peripheral edge surface 33' by a non-zero and constant angle α4, preferably 40°, with a tolerance of ±5°.

[0073] Also, the width W4 of this preliminary chamfer 39 is non-zero and remains constant around the main axis A1. Measured radially in relation to the central axis A1, this width W4 is greater than 0.1 mm. In this step, this width W4 is 0.2 - 0.3 mm.

[0074] The second step has a step of polishing the first main surface 31, the preliminary chamfer 39, and the peripheral edge surface 33 of the semi-finished formed shell 30' to remove material (along line 38 in FIG. 5) so as to generate the flat surface 34 and the first chamfer 36 (see FIG. 6).

[0075] For this purpose, at least a material thickness of 0.03 mm is removed from the peripheral edge surface 33 and from the preliminary chamfer 39.

[0076] Actually, this polishing step has a first sub-step in which the preliminary chamfer 39 is reduced and the flat surface 34 is generated, and a second sub-step in which the first chamfer 36 is finished.

[0077] The first sub-step is carried out using a polishing device such as a device sold under the brand "Kwangjin KJ-4 spherical polishing machine".

[0078] In this first sub-step, the semi-finished formed shell 30' is blocked on the support part, and its first main surface 31 is pressed in a state of being in pressure contact with the polishing pad, and then rubbed against it in a state of being in pressure contact therewith during reverse rotation. In other words, the grinding is carried out along an axis substantially parallel to the spindle A1.

[0079] In this process, the flat surface 34 has grown until it reaches the target size. At the same time, the preliminary chamfer 39 is also partially removed until it reaches another target size.

[0080] At the end of this first sub-step, the semi-finished formed shell 30' is - such that the flat surface 34 has a width that is non-zero and constant about the spindle, and preferably 0.5 to 0.6 mm when measured radially in relation to the central axis A1, and - the remaining part of the preliminary chamfer 39 (forming the first chamfer 36) also has a width that is non-zero and constant about the spindle, and preferably equal to 0.13 mm with a tolerance of ±0.02 mm when measured radially in relation to the central axis A1, and is polished.

[0081] There is no other finishing process for the flat surface 34.

[0082] The second sub-step is carried out using another polishing device, which is a device sold under the brand of "CP-8 Auto Lens Polishing Machine".

[0083] This device is separate from the previous ones because the forming shell is held in a different manner. In the first sub-step, the first main surface 31 is pressed only downward against the polishing tool or pad. Conversely, in this second sub-step, the forming shell is held by capturing it between two cylinders on the main surfaces 31, 32 in order to press the edge surface 33 against the lower polishing wheel.

[0084] In this sub-step, only the edge surface 33 of the forming shell is pressed in a pressing contact state against the polishing pad and rubbed against it in a pressing contact state in the opposite direction. In other words, the grinding is performed along an axis that is substantially radial with respect to the spindle A1 (or more radial than in the previous sub-step).

[0085] As a result, the edge surface 33 is polished and its diameter is reduced until it reaches the target size. At the same time, the first chamfer 36 is also partially removed until it reaches its target size (0.08 mm).

[0086] At the end of this second sub-step, the forming shell 30 is realized and has the shape described above.

[0087] The present invention is in no way limited to the described and illustrated embodiments. Specifically, the given widths and angles may vary slightly.

Claims

1. An ophthalmic lens forming shell (30) having two main surfaces (31, 32) and an edge surface (33) surrounding the main surfaces (31, 32), wherein a first one of the main surfaces (31) is adapted to face another forming shell (20) during the formation of the ophthalmic lens. In the ophthalmic lens forming shell (30), - a flat surface (34) extending along the outer edge of the first main surface (31); - a first chamfer (36) extending along the outer edge of the flat surface (34) between the flat surface (34) and the edge surface (33); The ophthalmic lens forming shell (30) is characterized by further comprising the above.

2. The ophthalmic lens forming shell (30) according to claim 1, wherein the flat surface (34) has a width (W3) equal to 0.5 mm with a tolerance of ±0.1 mm.

3. In a state where the edge surface (33) extends around the central axis (A1), in each cross-section of the first chamfer (36) in a plane passing through the central axis (A1), the first chamfer (36) is inclined at an angle (α1) of 40° with respect to the flat surface (34) with a tolerance of ±5°. The ophthalmic lens forming shell (30) according to any one of claims 1 to 2.

4. In a state where the edge surface (33) extends around the central axis (A1), the first chamfer (36) has a width (W1) measured in the radial direction with respect to the central axis (A1) equal to 0.08 mm with a tolerance of ±0.05 mm. The ophthalmic lens forming shell (30) according to any one of claims 1 to 3.

5. The ophthalmic lens forming shell (30) according to any one of claims 1 to 4, further comprising a second chamfer (35) disposed between the edge surface (33) and the other main surface (32).

6. In a state where the edge surface (33) extends around the central axis (A1), in each cross-section of the second chamfer (35) in a plane passing through the central axis (A1), the second chamfer (35) is inclined at an angle (α2) of 45° with respect to the edge surface (33) with a tolerance of ±5°. The ophthalmic lens forming shell (30) according to claim 5.

7. In a state where the edge surface (33) extends around the central axis (A1), the second chamfer (35) has a width (W2) measured in the radial direction in relation to the central axis (A1) equal to 0.5 mm, with a tolerance of +0.2 mm or -0.1 mm. The ophthalmic lens forming shell (30) according to any one of claims 5 or 6.

8. A process for manufacturing an ophthalmic lens forming shell (30), - A step of machining a raw piece to obtain a semi-finished forming shell (30') having two main surfaces (31, 32) and an edge surface (33) surrounding the main surfaces (31, 32), wherein the first of the main surfaces (31) is adapted to face another forming shell (20) during the forming of the ophthalmic lens, and a preliminary chamfer (39) is arranged between the edge surface (33) and the first main surface (31). The step of machining, - A step of polishing, 〇 A flat surface (34) extending along the outer edge of the first main surface (31), and, 〇 A first chamfer (36) extending along the outer edge of the flat surface (34) between the flat surface (34) and the edge surface (33), A step of polishing the preliminary chamfer (39) and the edge surface (33) to generate the above, A process having.

9. In the polishing step, at least 0.03 mm of material thickness is removed from the edge surface (33) and / or from the preliminary chamfer (39). The process according to claim 8.

10. The polishing step has a first sub-step in which the preliminary chamfer (39) is reduced and the flat surface (34) appears, and a second sub-step in which the first chamfer (36) is finished. The process according to any one of claims 8 to 9.

11. At the end of the first sub-step, the flat surface (34) has a width measured in the radial direction in relation to the central axis (A1) of the edge surface (33) that is 0.5 to 0.6 mm, and the first chamfer (36) has a width equal to 0.13 mm with a tolerance of ±0.02 mm. The process according to claim 10.

12. In a state where the edge surface (33) extends around the central axis (A1), at the end of the machining step, the preliminary chamfer (39) is - In relation to the edge surface (33), it is inclined by an angle (α4) of 40 degrees with a tolerance of ±5 degrees. - The process according to any one of claims 8 to 11, having a width (W4) measured radially in relation to the central axis (A1) of 0.8 mm with a tolerance of ±0.05 mm.

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