WO2009096085A1 - レンズ用鋳型の製造方法 - Google Patents
レンズ用鋳型の製造方法 Download PDFInfo
- Publication number
- WO2009096085A1 WO2009096085A1 PCT/JP2008/071352 JP2008071352W WO2009096085A1 WO 2009096085 A1 WO2009096085 A1 WO 2009096085A1 JP 2008071352 W JP2008071352 W JP 2008071352W WO 2009096085 A1 WO2009096085 A1 WO 2009096085A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- mold
- temperature
- molding
- glass material
- region
- Prior art date
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B23/00—Re-forming shaped glass
- C03B23/0026—Re-forming shaped glass by gravity, e.g. sagging
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B25/00—Annealing glass products
- C03B25/04—Annealing glass products in a continuous way
- C03B25/06—Annealing glass products in a continuous way with horizontal displacement of the glass products
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B29/00—Reheating glass products for softening or fusing their surfaces; Fire-polishing; Fusing of margins
- C03B29/04—Reheating glass products for softening or fusing their surfaces; Fire-polishing; Fusing of margins in a continuous way
- C03B29/06—Reheating glass products for softening or fusing their surfaces; Fire-polishing; Fusing of margins in a continuous way with horizontal displacement of the products
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D11/00—Producing optical elements, e.g. lenses or prisms
- B29D11/00009—Production of simple or compound lenses
- B29D11/0048—Moulds for lenses
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2909/00—Use of inorganic materials not provided for in groups B29K2803/00 - B29K2807/00, as mould material
- B29K2909/08—Glass
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2011/00—Optical elements, e.g. lenses, prisms
- B29L2011/0016—Lenses
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
Definitions
- the present invention relates to a method for producing a lens mold by a hot sag molding method.
- Glass molds for spectacle lenses are molded using a heat-resistant mold created by mechanical grinding and polishing, or electrical machining such as mechanical grinding or electrical discharge machining.
- the hot drooping molding method involves placing a glass material on a mold, heating it to a temperature above its softening point, softening the glass material and bringing it into close contact with the mold, thereby transferring the shape of the mold onto the upper surface of the glass material.
- This is a molding method for obtaining a molded product having a surface shape.
- heating of a glass raw material can be performed in a batch type heating furnace or a continuous heating furnace, the continuous heating furnace is widely used from the point of productivity.
- the temperature inside the furnace is controlled so as to have a predetermined temperature distribution in the transfer direction, so that the temperature rising process, the high temperature holding process, the temperature falling process, etc.
- a series of processes can be continuously performed in a furnace.
- the continuous heating furnace has a temperature distribution in the conveying direction as described above, the amount of deformation tends to be nonuniform in each part of the surface of the heating object.
- a glass material is formed by a hot drooping molding method in a continuous heating furnace having a temperature distribution such that the temperature increases from the inlet to the outlet, the glass material becomes higher in temperature earlier and increases in deformation. If the amount of deformation varies depending on the position of the glass material, the timing of close contact with the molding surface varies greatly depending on the position of the lower surface of the glass material. The error may become asymmetric and the wearing feeling of the glasses may be reduced.
- Japanese Patent Application Laid-Open No. 63-306390 is for ceramic products being fired, metallized, brazed and joined in a continuous heating furnace. It has been proposed to increase the uniformity of heating by rotating an object to be heated in a furnace. However, in the molding of the glass material by the hot sag forming method, the molding accuracy may be lowered if the glass material in the middle of softening is rotated greatly.
- an object of the present invention is to provide a spectacle lens mold capable of forming a spectacle lens having excellent wearing feeling by a hot droop molding method using a continuous heating furnace.
- a progressive addition lens having a progressive surface whose refractive power continuously changes from the upper part to the lower part is widely used as a bifocal lens.
- the near portion has a large curvature (the curve is deep), and the far portion has a small curvature (the curve is shallow). Therefore, the molding surface of the mold for forming the progressive surface also has a large curvature at the near portion molding portion and a curvature at the far portion molding portion.
- the molding surface of the mold for molding the mold molding surface by the hot droop molding method also has a large curvature at the part corresponding to the near part molding part of the mold molding surface, and corresponds to the far part molding part.
- the curvature becomes smaller at the part where it goes. Therefore, the present inventors utilize this shape characteristic and the non-uniformity of heating in the continuous heating furnace, and in the region where the temperature rises in the direction of conveyance of the mold in the continuous heating furnace, the near part molding.
- the present invention introduces a molding die in which the glass material to be molded is placed on the molding surface into a continuous heating furnace, and heat treatment while transporting the inside of the furnace, the upper surface of the glass material to be molded,
- a method for producing a lens mold which is molded into a molding surface shape for forming a surface including a progressive surface, Controlling the temperature of the continuous heating furnace so as to include a temperature rising region having a temperature distribution in which the temperature rises in the mold conveyance direction; Using a mold having a curvature distribution on the molding surface as the mold; and In the above temperature rising region, the portion on the side of the conveyance direction that is perpendicular to the conveyance direction of the mold and bisected by the virtual straight line passing through the geometric center of the molding surface includes a portion having the maximum curvature on the molding surface. Conveying the mold to It is related with the said manufacturing method containing.
- the conveyance in the temperature rising region can be performed such that the direction in which the average curvature is maximum from the geometric center of the molding surface toward the peripheral portion is substantially equal to the conveyance direction.
- the temperature of the continuous heating furnace can be controlled from the mold inlet side so that the temperature raising region, the constant temperature holding region, and the cooling region are arranged in this order.
- the manufacturing method may include rotating and swinging the mold.
- the swing angle and amplitude in the rotational swing can be determined based on the addition refractive power and / or inset amount of the lens.
- the swing angle in the rotational swing can be in the range of ⁇ 5 to 45 ° with respect to the transport direction, and the amplitude can be in the range of 0.01 to 1 Hz.
- the constant temperature holding region has a curvature on the molding surface at a portion opposite to the conveyance direction side that is perpendicular to the conveyance direction of the mold and is bisected by a virtual straight line passing through the geometric center of the molding surface. Rotating the mold to include the largest portion can be included.
- the temperature of the glass material to be molded placed on the mold that is conveyed in the constant temperature holding region can be equal to or higher than the glass transition temperature of the glass.
- the surface including the progressive surface may be a composite surface of a toric surface and a progressive surface.
- the mold may have two points on the imaginary straight line where the curvature is maximum on the straight line, at opposite positions where the distance from the geometric center is substantially equal, and the method includes: As the continuous heating furnace, a continuous heating furnace including a side heating region in which heat sources are arranged on both side surfaces is used, and in the side heating region, the mold conveyance direction is substantially the virtual line. Conveying the mold so as to be orthogonal to each other.
- the side heating region may be a region in which the glass material to be molded is heated to a temperature higher than the glass transition temperature of the glass.
- the glass material to be molded is a glass whose bottom surface is spherical, flat or aspherical with central symmetry, glass whose top and bottom surfaces are spherical, or glass having any one of the above shapes, and an astigmatism component ( Glass containing toric) can be used.
- a lens mold capable of forming a spectacle lens having excellent wearing feeling can be manufactured with high productivity.
- the present invention introduces a molding die in which a glass material to be molded is placed on a molding surface into a continuous heating furnace, and performs heat treatment while conveying the inside of the furnace.
- the present invention relates to a method for manufacturing a lens mold (hereinafter also referred to as “Aspect I”) in which the upper surface of the glass material to be molded is formed into a molding surface shape for forming a surface including a progressive surface.
- the temperature of the continuous heating furnace is controlled so as to include a temperature rising region having a temperature distribution in which the temperature rises in the mold conveying direction.
- the mold produced according to aspect I can be a progressive power lens mold.
- a progressive power lens is a lens that has a distance portion and a near portion, and has a progressive surface in which the refractive power gradually changes from the distance portion to the near portion.
- the progressive power lens includes a convex (outer surface) progressive power lens in which a progressive surface is disposed on a convex surface and a concave (inner surface) progressive power lens in which a progressive surface is disposed on a concave surface.
- the convex progressive-power lens has a progressive surface on the convex surface, and forms a progressive refractive power by the surface shape of the optical surface of the convex surface.
- the concave refractive power lens is the same except for the difference in the unevenness.
- the progressive-power lens that can be molded by the mold manufactured according to the present invention may be any of the above-described embodiments.
- the lens mold is manufactured by a thermal drooping method.
- FIG. 1 shows an explanatory diagram of the hot sag forming method.
- the heat treatment is performed in a state where the glass material to be molded is arranged on the mold (FIG. 1 (a)) so that the glass material lower surface center part and the mold surface are separated. Apply.
- the lower surface of the glass material to be molded is deformed by its own weight and is in close contact with the molding surface (FIG. 1B), and the shape of the molding surface is transferred to the upper surface of the glass material. It can be formed into a shape.
- the produced mold can be used as an upper mold or a lower mold of a mold for producing a plastic lens by a casting polymerization method. More specifically, the mold is assembled by combining the upper mold and the lower mold with a gasket or the like so that the upper surface of the glass material molded by the hot droop molding method is placed inside the mold, and the plastic lens is inserted into the cavity of the mold.
- a lens having a progressive surface can be obtained by injecting the raw material liquid and performing a polymerization reaction.
- the curvature is maximum (the radius of curvature is minimum) in the near portion, and the curvature is minimum (the radius of curvature is maximum) in the distance portion. Therefore, also on the molding surface of the mold (the surface disposed inside the mold cavity during casting polymerization), the curvature is maximized in the near portion molding portion and the curvature is minimized in the distance portion molding portion. And also in the molding surface of the mold for hot drooping molding for producing the mold, the curvature is maximum in the near part molding part equivalent part (the part for molding the upper surface of the glass material into the near part molding part).
- the curvature is minimized in the portion corresponding to the near portion forming portion (the portion for forming the upper surface of the glass material into the distance portion forming portion). That is, the molding die has a curvature distribution on the molding surface, and has different curvatures at any two points on at least a part of the molding surface. In this way, in order to bring the molding surface with different curvatures in the surface into close contact with the lower surface of the glass material to be molded, the portion to be brought into close contact with the near portion forming portion is largely deformed, and the distance portion forming portion is equivalent. The deformation of the part to be in close contact with the part should be small.
- the continuous heating furnace is temperature-controlled so as to include a temperature rising region having a temperature distribution in which the temperature rises in the mold conveying direction, and in the temperature rising region, the mold conveying direction It is necessary to greatly deform the part on the side of the conveyance direction, which is divided by a virtual straight line passing through the geometric center of the molding surface, in order to closely contact the portion having the maximum curvature on the molding surface, that is, the molding surface.
- the mold is conveyed so that a certain part is included.
- the object to be heated is rotated so that the heating state becomes uniform as a countermeasure against the heating non-uniformity due to the temperature distribution in the continuous heating furnace.
- the progressive heating lens is used by using the continuous heating furnace.
- the mold for use can be mass-produced with high productivity.
- a method for producing a lens mold for forming a lens having a composite surface of a toric surface and a progressive surface as a surface including a progressive surface (hereinafter, also referred to as “embodiment II”) is given.
- the embodiment II relates to a method for producing a lens mold for molding a lens having a composite surface of a toric surface and a progressive surface.
- Aspect II introduces a molding die in which the glass material to be molded is placed on the molding surface into a continuous heating furnace, and heat treatment while transporting the inside of the furnace, the upper surface of the glass material to be molded, Forming into a molding surface shape for forming the composite surface;
- the molding die two points on the imaginary straight line having a curvature distribution in the plane and passing through the geometric center, the two points having the maximum curvature on the straight line, and opposing positions having substantially the same distance from the geometric center
- a mold having a molding surface As the continuous heating furnace, a temperature distribution in which a continuous heating furnace including a side heating region in which heat sources are arranged on both side surfaces is used, and the temperature of the continuous heating furnace rises in the mold conveyance direction.
- Temperature controlled to include a temperature rising region having Conveying the mold so that the mold conveyance direction is substantially orthogonal to the virtual straight line in the side heating region; and In the temperature rising region, the mold is transported so that the part of the transport direction side orthogonal to the mold transport direction and bisected by the virtual straight line includes a portion having the maximum curvature on the molding surface. , Is further included.
- the molding surface of the mold for forming the progressive surface also has a large curvature at the near portion molding portion and a curvature at the far portion molding portion.
- the molding surface of the mold for molding the mold molding surface by the hot droop molding method also has a large curvature at the part corresponding to the near part molding part of the mold molding surface, and corresponds to the far part molding part.
- the spectacle lens has two points with the maximum curvature at symmetrical positions on the main meridian on the toric surface. At the point where the curvature is maximum on the main meridian, the curve is deepest on the main meridian.
- the molding surface of the mold for forming such a toric surface also has two points on the axis corresponding to the main meridian that have the maximum curvature at symmetrical positions.
- two points on the axis corresponding to the main meridian are maximized on the axis corresponding to the main meridian, It has a symmetrical position. That is, on the mold forming surface, there are two axes at which the curvature is maximum and an axis having a symmetrical position with respect to the geometric center.
- the present inventors utilize the shape characteristics of the forming surface for forming the progressive surface and the nonuniformity of heating in the continuous heating furnace, and In the region where the temperature rises in the direction of conveyance of the mold in the heating furnace, the molding die (glass material is placed on the molding surface so that the near part molding part equivalent side is the front and the far part molding part equivalent side is the rear. It was newly found that the deformation by heat softening can be controlled and the molding surface can be easily formed. Furthermore, the present inventors utilize the shape characteristics of the molding surface for forming the toric surface, and place the molding die in which the glass material to be molded is placed in a continuous heating furnace in which heat sources are arranged on both sides.
- a molding surface can be easily formed by controlling deformation due to heat softening by passing an axis corresponding to the main meridian so as to be substantially orthogonal to the conveying direction. For example, in a continuous heating furnace having a temperature distribution such that the temperature increases from the inlet to the outlet, if the glass material to be molded is placed on the molding surface having the above shape and then molded, the conveyance direction side (high temperature side) Because it deforms quickly, the timing of close contact with the molding surface varies greatly depending on the position of the lower surface of the glass material, and astigma that is unnecessary for spectacle correction occurs, or the error from the design value becomes asymmetrical and the wearing feeling of the glasses decreases. There are things to do.
- a spectacle lens mold having a composite surface of a toric surface and a progressive surface is produced by a thermal drooping method.
- a spectacle lens having a composite surface of a toric surface and a progressive surface a double-sided aspheric type progressive addition lens can be mentioned.
- Such spectacle lenses have a composite surface having an axially symmetric shape including toric and a non-symmetrical shape including progressive elements.
- the composite surface is, for example, symmetrical with respect to an axis passing through the main meridian, and the meridian direction is not symmetrical but has a different curvature.
- the convex surface of a double-sided aspherical progressive-power lens has an axisymmetric shape with respect to the meridian passing through the geometric center, and the sagittal height at the position farthest away from the meridian has a shape in which one curvature increases in the meridian direction. And the opposite direction has an asymmetric shape with a small curvature.
- a shape having a large curvature corresponding to the near refractive power is included in only one side of the main meridian that is symmetrical with respect to the main meridian.
- the maximum direction of curvature having axial symmetry and the maximum curvature having no symmetry are respectively specified and correspond to the specified reference position. Then, the conveying direction of the mold is determined. Details of the transport method will be described later.
- the lens having the composite surface has two points on the principal meridian that have the maximum curvature, and symmetrical positions (positions having substantially the same distance from the geometric center). That is, on the main meridian, there are two points where the curve is deepest, at symmetrical positions.
- two points having the maximum curvature exist on the axis corresponding to the main meridian at symmetrical positions.
- two points on the axis corresponding to the main meridian are the same as the mold molding surface, It exists in a symmetrical position.
- deformation control on the toric surface is performed as described above.
- the deformation control on the progressive surface is performed as described above.
- the timing of contact between the lower surface of the glass material and the molding surface can be made uniform in the surface. If the timing at which the lower surface of the glass material and the molding surface are in close contact with each other is significantly different in each part of the surface, stigma that is not necessary for correction of spectacles may occur, or the error from the design value may become asymmetrical, reducing the wearing comfort of the glasses.
- a mold capable of forming a spectacle lens having excellent wearing feeling can be obtained.
- the glass material that forms the upper surface by passing through the continuous heating furnace is preferably a glass material in which the shape of the lower surface to be brought into close contact with the molding surface is a spherical surface, a plane surface, or an aspheric surface having central symmetry. It is. This is because, for example, the lower surface of a spherical glass material has a constant curvature within the surface, and therefore, when closely contacting a molding surface having a different curvature within the surface, the difference in the amount of deformation within the surface becomes particularly obvious. Because. The same applies to the case where the lower surface of the glass material is an aspherical surface having a plane and central symmetry.
- the amount of heat deformation of the glass material can be controlled in the continuous heating furnace. Furthermore, a glass material having a lower surface of the above shape and containing an astigmatic component (toric) on the upper surface is also suitable as the glass molding material.
- the lower surface shape of the glass material to be molded is as described above.
- the shape of the upper surface of the glass material to be formed is not particularly limited, and may be various shapes such as a spherical surface, a flat surface, and an aspheric surface.
- the glass material to be molded has a spherical shape on the upper surface and the lower surface. Since a glass material having a constant curvature on both the upper and lower surfaces is easy to process, the use of the glass material having the above shape is effective in improving productivity.
- the glass material is preferably a glass material having a concavo-convex surface having a spherical shape and having an equal thickness or substantially equal thickness in the normal direction.
- substantially equal thickness in the normal direction means that the rate of change of the thickness in the normal direction measured at least at the geometric center on the glass material is 1.0% or less, preferably 0.8% or less. Say something. A schematic cross-sectional view of such a glass material is shown in FIG.
- the glass material 206 has a meniscus shape having an uneven surface, and the outer shape is circular. Furthermore, the glass material concave surface 202 and the convex surface 201 are both spherical in shape.
- the normal direction on both surfaces of the glass material indicates a direction in which an angle formed with the glass material surface at an arbitrary position on the glass material surface is vertical. Therefore, the normal direction changes depending on each position on the surface.
- the direction 204 in FIG. 2 represents the normal direction at the point 208 on the concave surface of the glass material, and the intersections between the normal direction 204 and the concavo-convex surface are 208 and 209, respectively. It becomes the thickness in the direction.
- the normal directions thereof are a direction 203 and a direction 205, respectively.
- the distance between 210 and 211 is the thickness in the normal direction
- the distance between 212 and 213 is the thickness in the normal direction.
- the normal direction spacing between the upper and lower surfaces is thus the same value. That is, in a glass material having an equal thickness in the normal direction, the upper and lower surfaces are part of a spherical surface sharing the same center (207 in FIG. 1).
- the substantially circular glass material as described above has a shape having central symmetry at the geometric center.
- the molding surface has a shape corresponding to the molded product (mold)
- the curve corresponding to the near part molding part is large, and the curve corresponding to the distance part molding part is smaller than that.
- the glass material shape change amount is large in the direction of higher temperature in the thermal softening process in response to the temperature non-uniformity unique to the continuous heating furnace in which the temperature rises in the traveling direction of the workpiece.
- the glass material can be approximated to a viscoelastic body as described in WO2007 / 058353A1, the entire description of which is specifically incorporated herein by reference, it is normal before and after heat softening by the hot drooping molding method. Since the glass thickness in the direction does not substantially change, the use of a glass material having an equal thickness in the normal direction also has an advantage of easy shape control during heat softening.
- the outer diameter of the glass material is sufficiently large with respect to the thickness in the normal direction of the glass material, and the glass material with respect to the vertical deformation amount of the glass. It is preferable that the outer diameter is sufficiently large.
- the thickness of the glass material used in the present invention is preferably 2 to 10 mm, more preferably 5 to 7 mm.
- the outer diameter of the glass material is preferably 60 to 90 mm, and more preferably 65 to 86 mm.
- the outer diameter of a glass material shall mean the distance of the arbitrary points of the lower surface peripheral edge part of a glass raw material, and the point which opposes on a peripheral edge part.
- group, etc. are suitable.
- glass glass components first, for example, SiO 2 , B 2 O 3 and Al 2 O 3 are included, and the glass material composition is SiO 2 45 to 85% and Al 2 O 3 4 to 4 by mole percentage.
- Na 2 O + Li 2 O 8-30% (where Li 2 O is 70% or less of Na 2 O + Li 2 O), and the total amount of ZnO and / or F 2 is 2-13% (where F 2 ⁇ 8 %)
- Li 2 O + Na 2 O / Al 2 O 3 is 2/3 to 4/1
- SiO 2 + Al 2 O 3 + Na 2 O + Li 2 O + ZnO + F 2 > 90% is suitable.
- the glass material composition is 50 to 76% SiO 2 , 4.8 to 14.9% Al 2 O 3 , and 13.8 to 27.3% Na 2 O + Li 2 O in terms of mole percentage.
- Li 2 O is 70% or less of Na 2 O + Li 2 O
- the total amount of ZnO and / or F 2 is 3 to 11% (where F 2 ⁇ 8%)
- Li 2 O + Na 2 O / Al 2 O 3 A glass having a ratio of 2/3 to 4/1, SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + Li 2 O + ZnO + F 2 > 90% is suitable.
- SiO 2 (63.6%), Al 2 O 3 (12.8%), Na 2 O (10.5%), B 2 O 3 (1.5%), ZnO ( A glass composition composed of 6.3%), Li 2 O (4.8%), As 2 O 3 (0.3%), and Sb 2 O 3 (0.2%) is more preferable.
- other metal oxides such as MgO, PbO, CdO, B 2 O 3 , TiO 2 , ZrO 2, and colored metal oxides may be used for stabilizing glass, facilitating melting, coloring, etc. within a range not exceeding 10%. Can be added for.
- the thermal properties are a strain point of 450 to 480 ° C., a cooling point of 480 to 621 ° C., a softening point of 610 to 770 ° C., a glass transition temperature (Tg) of 450 to 620 ° C.
- the point (Ts) is 535 to 575 ° C.
- the specific gravity is 2.47 to 3.65 (g / cm 3 )
- the refractive index is Nd 1.52300 to 1.8061
- the thermal diffusion ratio is 0.3 to 0.4 cm 2.
- a strain point of 460 ° C. a cooling point of 490 ° C., a softening point of 650 ° C., a glass transition temperature (Tg) of 485 ° C., a yield point (Ts) of 535 ° C., a specific gravity of 2.47 (g / cm 3 ), and refraction.
- the rate is Nd1.52300, the thermal diffusion ratio is 0.3576 cm 2 * min, the Poisson ratio is 0.214, the photoelastic constant is 2.82 ⁇ 10E-12, the Young's modulus is 8340 kgf / mm 2 , and the linear expansion coefficient is 8.5 ⁇ 10E.
- a glass material of ⁇ 6 / ° C. is particularly suitable.
- the heat source of the continuous heating furnace is provided above and / or below the heating object conveyance path.
- surfaces can be provided in a continuous heating furnace.
- This region is preferably at least a region where the softening deformation of the glass proceeds, and more preferably a region where the glass material to be molded is heated to the glass transition temperature or higher of the glass.
- the side heating region can be at least a temperature rising region, preferably a temperature rising region and a constant temperature holding region, and more preferably a furnace including a temperature rising region, a constant temperature holding region and a cooling region. It can be the entire area.
- the conveyance of the mold in the lateral heating region is a straight line passing through the geometric center on the molding surface of the mold, and has two points where the curvature is maximum on the straight line, from the geometric center. Assuming a virtual straight line at opposite positions where the distances are substantially equal, this virtual straight line is carried out so that the transport direction is substantially orthogonal.
- the mold for spectacle lenses manufactured according to aspect II is for molding a spectacle lens having a composite surface of a toric surface and a progressive surface.
- the toric surface has two points with the maximum curvature at symmetrical positions on the main meridian.
- the mold forming surface for forming this toric surface has a straight line transferred to the main meridian.
- a straight line corresponding to the straight line transferred to the main meridian that is, a line corresponding to the main meridian of the toric surface of the spectacle lens also exists on the mold forming surface for forming the mold forming surface.
- the virtual straight line is a line corresponding to the main meridian of the toric surface of the spectacle lens. If the side heating region is passed so that the virtual straight line and the conveying direction are orthogonal, two deep curves can be heated evenly, and the timing of adhesion between the glass material lower surface and the mold forming surface can be controlled. Can be made uniform within.
- “the distance from the geometric center is substantially equal” includes that the distance from the geometric center is the same and that the distance differs by about 1 mm or less.
- the transport direction in the lateral heating region may be the above direction, but considering workability, it is preferable that the transport direction is the above direction from the time of introduction of the continuous heating furnace.
- a part of the period during which the imaginary straight line and the conveyance direction are not substantially orthogonal may be included, but for the deformation control, the period is 10% to 15%. It should be suppressed to the extent, preferably in the constant temperature holding region, more preferably in the region heated to Tg or more.
- the virtual straight line is, for example, a straight line corresponding to an axis in the maximum curvature direction that is symmetrical with the spectacle lens on the molding surface. Or it can also identify from the three-dimensional shape measurement of a shaping
- the heat source provided on the side surface of the heating furnace is a shape in which surface or rod-like heaters are arranged in parallel and vertically, and the height is higher than the heating object.
- a plurality of ones can be arranged in the direction of the lateral side of the object. Heating from the heat sources on both sides is preferably performed by controlling the temperature by using one to a plurality of heater zones arranged in the traveling direction or height direction, and under the same conditions from both sides in order to increase the uniformity of heating. .
- a mold capable of forming a spectacle lens having excellent wearing feeling can be obtained.
- the portion where the curvature is maximized is a portion corresponding to the near portion molding portion on the molding surface. More specifically, it may be a position corresponding to the near-site measurement reference point on the molding surface.
- a refractive power measurement reference point is defined in JIS T7315, JIS T7313, or JIS T7330.
- the refractive power measurement reference point is a portion surrounded by a circle having a diameter of, for example, about 8.0 to 8.5 mm on the object side or eyeball side surface of the spectacle lens.
- the spectacle lens that can be molded by the mold manufactured according to the present invention has two refractive power measurement reference points, a distance measurement reference point and a near measurement reference point.
- An intermediate region located between the distance measurement reference point and the near measurement reference point of the progressive power lens is called a progressive zone, and the refractive power changes progressively.
- the near-field measurement reference point is arranged at a position corresponding to the convergence of the eyeball at either the left or right position from the main meridian, and it is determined whether it is arranged at the right or left of the main meridian according to the right or left division of the eyeball.
- the “position corresponding to the refractive power measurement reference point” of the molding surface of the mold is preferably a method in which a portion of the upper surface of the glass material that is transferred to the refractive power measurement reference point of the spectacle lens on the mold surface to be manufactured is preferably a method.
- the part which adheres to the glass material lower surface which opposes in a line direction shall be said.
- FIG. 3 shows an arrangement example of “position corresponding to the distance measurement reference point” and “position corresponding to the near measurement reference point” on the molding surface of the mold.
- the mold in the temperature rising region, is so shaped that the portion on the molding surface that has the maximum curvature is included in the portion in the conveyance direction that is perpendicular to the conveyance direction of the mold and is divided by the virtual straight line.
- Transport for example, in the aspect shown in FIG. 3, the portion having the maximum curvature on the molding surface is included in a position corresponding to the near portion measurement reference point.
- the line corresponding to the main meridian coincides with the mold conveying direction in the temperature rising region in the continuous heating furnace, it is orthogonal to the mold conveying direction and passes through the geometric center of the molding surface.
- the imaginary straight line is a straight line (line A in FIG.
- the present invention is not limited to a mode in which the line corresponding to the main meridian in the temperature rising region is conveyed so as to coincide with the mold conveying direction.
- the conveyance in the temperature rising region is performed such that the direction in which the average curvature is maximum from the geometric center of the mold forming surface toward the peripheral edge is substantially equal to the conveyance direction.
- the direction in which the average curvature is maximized from the geometric center of the mold surface to the peripheral portion is, for example, the direction indicated by the white arrow on the molding surface in the embodiment shown in FIG. The direction is toward the position corresponding to the reference point.
- this direction is the direction with the strongest curve on the molding surface, it is preferable to make this direction substantially coincide with the conveying direction in the temperature rising region in order to obtain a mold capable of molding a spectacle lens with good wearing feeling.
- the above “substantially equal” and “substantially coincide” include cases where they differ by about ⁇ 5 ° or less.
- a method for determining the conveyance direction in the temperature rising region in the continuous heating furnace first, a method (Method 1) for calculating and specifying the direction of the maximum curvature from the three-dimensional shape measurement of the molding surface, Can include a method (method 2) of specifying from the prescription value of the spectacle lens based on the astigmatism axis, the near-distance measurement reference point, and the far-distance measurement reference point.
- the conveyance direction may be determined based on the molding surface design value of the mold so that the position corresponding to the near-site measurement reference point is arranged on the high temperature side in the temperature rising region with the astigmatic axis as a reference.
- the method 1 will be described below.
- the approximate radius of curvature of the lens cross section in this direction is calculated from the coordinates of three or more points on a straight line passing through the geometric center of the mold surface.
- the radius of curvature in all directions is calculated by this calculation method, and the minimum radius of curvature and its direction are specified from the result.
- the approximate curvature radius is calculated by solving simultaneous equations from three points or calculating an approximate curvature radius from the coordinates of three or more points using the least square method.
- the surface shape of the molding surface of the mold can be represented by a numerical value of the height on each lattice of a lattice matrix obtained by dividing the height of the molding surface vertically and horizontally.
- the shape type is a free-form surface including a progressive surface shape. This free-form surface can be expressed using a B-spline function shown in the following equation 1 in order to obtain a coordinate value at an arbitrary position.
- Equation 1 m is the rank of the spline function (m ⁇ 1: degree), h and k are the number of nodes of the spline function ⁇ 2 m, cij is a coefficient, Nmi (x), and Nmj (y) are B-splines of the mth order. It is.
- spline function For details on the spline function, reference can be made to the document "Series: Mathematics 20 of New Applications, Spline Functions and Their Applications", authors Kozo Ichida, Fuji City Yoshimoto, published by Education Publishing. The entire description is hereby specifically incorporated by reference.
- the approximate radius of curvature in the cross section is calculated from the simultaneous equations of the circle equation using the coordinate values of the three points AOB on the straight line passing through the geometric center of the mold surface and connecting the ends.
- the three points used for the calculation are A (X1, Y1), O (X2, Y2), and B (X3, Y3)
- the coordinate value of the ZX cross section is A (X1, Z1), O (X2, Z2), B (X3, Z3).
- the approximate radius of curvature is obtained for the U1, U2,...
- the angle ⁇ can be set to 0.1 to 1 °, for example.
- a and b are the W and Z coordinate values of the center of the circle, r is the radius of the circle, and the coordinate values of W1, W2 and W3 are the same in all directions. Therefore, Z1, Z2, and Z3 are expressed by Equation 4 from the B-spline function.
- Table 1 shows an example of calculating the radius of curvature in a total of 18 directions with a pitch of 10 degrees on each axis on the progressive surface in the above method.
- P1, P2, and P3 are coordinate values on the axis
- the axial direction represents “an angle (deg) between the cross section to be calculated and the X-axis direction”. From Table 1, it can be specified that the direction of 60 degrees is the maximum curvature direction (minimum curvature radius direction).
- Equation 5 In order to obtain the equation of the circle closest to the n coordinate values, the simultaneous equations of Equation 5 below are solved using the least square method. However, it is a condition that all these points are not on a straight line in the ZX section.
- Equation 5 a and b are the X and Z coordinate values of the center of the circle, and r is the radius of the circle.
- Equation 5 When the S in Equation 5 is the smallest, it is the most approximate circle equation. Therefore, to obtain a, b, and r that minimizes S, S is differentiated with respect to a, b, and r, set to 0, and these are solved simultaneously as shown in Equation 6 below.
- the approximate radius of curvature is obtained for the U1, U2,...
- the angle ⁇ can be set to 1 °, for example.
- FIG. 9 when n coordinate points used for calculation in the direction of the angle ⁇ are (X1, Y1), (X2, Y2),..., (Xn, Yn), FIG. As shown, the coordinate values of the ZW cross section are (W1, Z1), (W2, Z2),..., (Wn, Zn).
- the following simultaneous equations are solved using the least square method. However, it is a condition that all these points are not on a straight line in the ZW cross section. If a and b are the W and Z coordinate values of the center of the circle, and r is the radius of the circle, the following equation 7 is obtained.
- each Z value (Z1, Z2, Z3) is obtained from the B-spline function (formula 9 below).
- the maximum curvature direction at three or more points can be specified in the same manner as the calculation at three points by the above method. Or, for example, three or more coordinate values, for example, four coordinate values, are arranged on a line segment between the geometric center and the end of the molding die forming surface, and the approximate curvature radius in the cross section is set.
- the maximum curvature radius may be specified by calculation.
- a continuous heating furnace is an apparatus that has an inlet and an outlet, and performs heat treatment by allowing a workpiece to pass through a furnace having a temperature distribution set by a conveyor such as a conveyor for a certain period of time.
- the temperature distribution inside the furnace can be controlled by a plurality of heaters taking into consideration heat generation and heat dissipation and a control mechanism of the air circulation in the furnace.
- heaters are installed at the upper and lower portions of the in-furnace transport path, but as described above, at least a part of the present invention can be provided with regions where heat sources are arranged on both side surfaces.
- the PID control can be used for temperature control of each sensor and heater of the continuous heating furnace.
- the PID control is a control method for detecting a deviation between a programmed desired temperature and an actual temperature and returning (feedback) the deviation from the desired temperature to zero.
- the PID control is a method of obtaining “proportional”, “integral”, and “differential” when calculating the output from the deviation.
- the general formula of PID control is shown below.
- e is a deviation
- K is a gain (a gain of a subscript P is a proportional gain
- a gain of a subscript I is an integral gain
- a gain of a subscript D is a differential gain
- ⁇ t is a sampling time (sampling time, control cycle)
- a subscript n indicates the current time.
- the continuous heating furnace is not limited as long as the desired temperature control is possible, but is preferably a continuous charging electric furnace.
- the conveyance method is a non-sliding method
- the temperature control is PID control
- the temperature measuring instrument is “Platinum K thermocouple 30 points”
- the maximum operating temperature is 800 ° C
- the normal operating temperature is 590 to 650 ° C
- the internal atmosphere is dry Air (oil dust free)
- atmosphere control can use an inlet air curtain, furnace purge, outlet air curtain
- temperature control accuracy is ⁇ 3 ° C.
- a cooling method is air cooling.
- a suction part for suction described later can be provided at, for example, three positions in the furnace.
- a glass material in a continuous heating furnace, can be heated to a desired temperature by radiation from a heat source in the furnace and secondary heat emitted from secondary radiation from the inside of the furnace.
- the temperature of the continuous heating furnace is controlled so as to include a temperature rising region having a temperature distribution in which the temperature rises in the mold conveyance direction.
- the glass material on the mold can be heated to a temperature at which the glass material can be deformed, preferably a temperature higher than the glass transition temperature of the glass constituting the glass material.
- the temperature raising region can be a predetermined region starting from the inlet of the continuous heating furnace.
- the temperature in the continuous heating furnace it is preferable to control the temperature in the continuous heating furnace so that a temperature rising region, a constant temperature holding region, and a cooling region are included from the inlet (molding die inlet) side.
- the glass material passing through the temperature-controlled furnace in this way is heated to a temperature that can be deformed in the temperature rising region, and molding of the upper surface proceeds in the constant temperature holding region, and then cooled in the cooling region and discharged outside the furnace. Is done. What is necessary is just to set suitably the length of each area
- the temperature of the glass material is preferably maintained at a temperature equal to or higher than the glass transition temperature of the glass constituting the glass material to be molded.
- the temperature of the glass material in the constant temperature holding region is preferably a temperature exceeding the glass transition temperature and below the glass softening point in terms of formability.
- the glass material temperature does not necessarily have to be kept constant in the constant temperature holding region, and the glass material temperature may change by about 1 to 15 ° C. in the region.
- the cooling region it is preferable to gradually cool the glass material formed in the constant temperature holding region to lower the temperature to room temperature.
- the heating or cooling temperature described below refers to the temperature of the upper surface of the glass material.
- the temperature of the upper surface of the glass material can be measured by, for example, a contact-type or non-contact-type thermometer.
- the conveyance direction in the above temperature rising region is set as described above.
- a molding die in which a glass material is arranged continuously so that a portion on the molding surface that has a maximum curvature is included in a portion on a conveyance direction side that is orthogonal to the conveyance direction of the molding die and is divided by the virtual straight line. It is introduced from the entrance of the regenerative heating furnace to the inside, and is continuously conveyed in the same direction inside the furnace.
- a glass material is placed on the molding surface.
- the glass material can be placed on the molding die so that the glass material contacts the molding surface at least at a part of the peripheral edge of the lower surface of the glass material and the center of the lower surface of the glass material is separated from the molding die.
- the molding die used in the present invention has molding surfaces with different curvatures in the plane as described above. In order to stably dispose a glass material having a spherical lower surface on such a molding surface, it is preferable to arrange the glass material so that at least three points on the peripheral edge of the lower surface are in contact with the molding surface.
- At least two points on the peripheral edge of the lower surface of the glass material on the position side corresponding to the distance refractive power measurement reference point of the spectacle lens and one point on the near refractive power measurement reference point side are in contact with the molding surface.
- a glass material is placed on the mold.
- the surface of the mold that is the upper surface of the glass material is transferred to the spectacle lens. .
- the “position corresponding to the refractive power measurement reference point” on the lower surface of the glass material refers to a glass that faces a portion of the upper surface of the glass material that is to be transferred to the refractive power measurement reference point of the spectacle lens on the obtained mold surface.
- the part on the lower surface of the material in order to stably arrange the glass material on the molding surface with the three points as supporting points, the lower surface of the glass material is an average curvature at the distance refractive power measurement reference point of the spectacle lens to be finally obtained. It is preferable to form a spherical shape having substantially the same average curvature.
- FIG. 11 is an explanatory view of the contact between the lower surface of the glass material and the mold forming surface for manufacturing the progressive-power lens mold.
- support points A, B, and C are contact points with the molding surface of the lower surface of the glass material.
- the support points A and B above the line corresponding to the horizontal line (also referred to as horizontal reference line or main meridian) of the lens passing through the two alignment reference positions are on the position side corresponding to the distance refractive power measurement reference point.
- the support point C below the meridian is one point on the position side corresponding to the near refractive power measurement reference point. As shown in FIG.
- the two points on the position side corresponding to the distance refractive power measurement reference point are symmetrical with respect to the line corresponding to the main meridian passing through the distance refractive power measurement reference point of the spectacle lens on the lower surface of the glass material. It is preferable to be located at. Further, as shown in FIG. 11, the support point on the position side corresponding to the near power measurement reference point is disposed at a position opposite to the near power measurement reference point with respect to the line corresponding to the main meridian. It is preferable.
- the “line corresponding to the main meridian passing through the distance refractive power measurement reference point” on the lower surface of the glass material means the portion of the upper surface of the glass material that is transferred to the portion where the main meridian of the spectacle lens is located on the mold surface.
- a closing member can be arranged on the mold on which the glass material is arranged, and the molding surface side open part of the mold on which the glass material is arranged can be closed. This can prevent the upper surface of the glass material from being contaminated by foreign matter such as dust in the air or dust in the furnace while passing through the continuous heating furnace. Details of the occluding member usable in the present invention are described in, for example, WO2007 / 058353A1.
- the mold conveying direction in the temperature rising area is as described above, but the position in the left-right direction of the mold may be kept constant during the conveyance in the temperature rising area, and it is rotated and swung at a predetermined angle and amplitude. You may let them. In consideration of the fact that the temperature distribution may not completely match on the left and right with respect to the central portion in the transport direction, it may be preferable to rotate and swing in order to increase the uniformity of heating in the left and right direction.
- the curvature of the intermediate region (progressive zone) existing between the distance portion and the near portion is defined by the addition refractive power and / or the inset amount. .
- the curvature increases as the addition power and / or inset amount increases.
- the rotation and swinging is performed within a range in which the above-described virtual straight line and the conveyance direction can be maintained substantially orthogonal.
- the swing angle during rotation swing is set in the range of ⁇ 5 to 45 ° with the transport direction as the reference (0 °).
- the amplitude is preferably set in the range of 0.01 to 1 Hz.
- the swing angle can be ⁇ 45 °
- the addition power 2D can be ⁇ 25 °
- the addition power 1D can be ⁇ 5 °.
- the mold In the temperature rising region, the mold is transferred so that the part to be greatly deformed is located on the high temperature side, but in the continuous heating furnace temperature controlled so that the temperature rising region, the constant temperature holding region, and the cooling region are positioned in this order. Takes a V-shaped temperature gradient, so that after a certain portion, the rear side becomes high in the conveying direction. Therefore, in the present invention, it is preferable to rotate the mold at a predetermined position so that the portion to be greatly deformed is located on the high temperature side even after the temperature rising region.
- the maximum temperature area in the furnace is in the constant temperature holding area, so in the constant temperature holding area, it is perpendicular to the conveyance direction of the mold and opposite to the conveyance direction side divided by a virtual straight line passing through the geometric center of the molding surface. It is preferable to rotate the molding die so that the portion on the side includes the portion having the smallest curvature on the molding surface.
- the mold in a relatively initial region in the constant temperature region, the mold can be inverted 180 ° preferably after the glass material temperature becomes equal to or higher than the glass transition temperature.
- the side heating area is included in the constant temperature holding area, the conveyance is continued so that the virtual straight line and the conveyance direction are substantially orthogonal after the rotation.
- the continuous heating furnace used in the present invention has a rotation mechanism that can rotate 180 ° to the left and right in order to enable the above-mentioned rotation swing and the above rotation.
- a rotation shaft can be provided on the base (support) on which the mold is placed so as to be positioned at the geometric center of the mold.
- the driving force can be transmitted and controlled by connecting the rotating shaft to a driving motor outside the furnace.
- the rotating mechanism can be arranged at an arbitrary position in the furnace, but it is also preferable that the rotating mechanism is arranged only in a suction part described later.
- a mold having a through-hole penetrating from the molding surface to the surface opposite to the molding surface is used, and suction is performed through the through-hole during molding. Can also be done.
- the mold having a through hole is described in detail in WO2007 / 058353A1. Since the temperature range in which the deformation promoting effect by suction can be remarkably obtained is usually the constant temperature holding region, in the present invention, it is preferable to perform the above suction in the constant temperature holding region.
- the temperature control in the continuous heating furnace is performed with a predetermined time as one cycle. Below, an example of temperature control which makes 17 hours 1 cycle is demonstrated. However, this invention is not limited to the aspect shown below.
- Temperature control in the furnace can be performed in seven steps.
- the first step is (A) a preliminary heating step
- the second step is (B) a rapid heating step
- the third step is (C) a slow heating step
- the fourth step is (D) constant temperature.
- the holding step and the fifth step are (E) a low-speed cooling step
- the sixth step is (F) a rapid cooling step
- the seventh step is (G) a natural cooling step.
- step (A) preliminary heating step fixing is performed at a constant temperature near room temperature for 90 minutes. This is to make the temperature distribution of each part of the glass material uniform and to easily reproduce the heat distribution of the glass material by controlling the temperature of heat softening.
- the fixing temperature is about room temperature (about 20-30 ° C.).
- the second step is a (B) rapid heating temperature raising step from room temperature (for example, 25 ° C.) to glass transition temperature (hereinafter also referred to as Tg) ⁇ 50 ° C. (hereinafter also referred to as T1), for example at a rate of 4 ° C./min. For about 90 minutes.
- Tg glass transition temperature
- T1 glass transition temperature
- T2 glass transition temperature
- T1 glass transition temperature
- T2 glass transition temperature
- T1 glass transition temperature
- T1 glass transition temperature
- T2 glass transition temperature
- the glass material heated at the temperature T2 is heated for 30 minutes in the constant temperature holding step. Further, heating is performed at temperature T2 for 30 minutes.
- suction processing from the through hole of the mold can also be performed in the latter half of 30 minutes.
- the suction process can be performed by operating a suction pump installed outside the electric furnace. When the suction pump performs suction, a negative pressure is generated, and the negative pressure sucks the glass material placed on the mold through the through hole of the mold.
- a pressure of, for example, 80 to 150 mmHg ( ⁇ 1.0 ⁇ 10 4 to 1.6 ⁇ 10 4 Pa) is applied by a suction port of a predetermined heat-resistant matrix. Aspirate with.
- the fifth step (E) which is a cooling step, is a low-speed cooling step, which cools to a Tg of ⁇ 100 ° C. (hereinafter also referred to as T3), for example, at a rate of 1 ° C./min for about 300 minutes, thereby fixing the shape change due to softening.
- This slow cooling process also includes an annealing element that removes the distortion of the glass.
- cooling is performed to about 200 ° C. at a rate of about 1.5 ° C./min.
- the glass and the mold that have been softened may be damaged due to differences in their thermal expansion coefficients with respect to their own thermal shrinkage and temperature changes. Therefore, it is preferable to reduce the temperature change rate to such an extent that it does not break.
- a natural cooling step (G) which is a seventh step, is performed.
- G In a natural cooling process, when it becomes 200 degrees C or less, it will cool to room temperature by natural cooling after that.
- the lower surface of the glass material and the molding surface are in a male-female relationship.
- the upper surface of the glass material is deformed according to the shape deformation of the lower surface of the glass material, and a desired optical surface is formed.
- the glass material can be removed from the mold and a molded product can be obtained.
- the molded product thus obtained can be used as a spectacle lens having a composite surface of a toric surface and a progressive surface, and preferably as a mold for a double-sided aspherical progressive-power lens.
- a part such as a peripheral portion may be removed and used as the spectacle lens mold.
- the continuous heating furnace including the side heating region described above can be used without being limited to the method for manufacturing a lens mold of the present invention.
- Examples of the method for producing a lens mold using the continuous heating furnace include the following modes (hereinafter referred to as “reference mode A”).
- a toric surface is formed on the upper surface of the glass material to be molded by introducing a mold having the glass material to be molded on the molding surface into a continuous heating furnace and carrying out heat treatment while transporting the inside of the furnace.
- a method for producing a lens mold having a toric surface, which is molded into a molding surface shape for As the molding die a molding die having two molding points on the virtual straight line passing through the geometric center and two opposing points at which the distance from the geometric center is substantially equal on the straight line is used.
- the continuous heating furnace a continuous heating furnace including a region (side heating region) in which heat sources are arranged on both side surfaces is used, and in the region, the mold conveyance direction is substantially orthogonal to the virtual straight line. Conveying the mold so that, The said manufacturing method containing.
- the side heating region may include a region in which the glass material to be molded is heated to the glass transition temperature or higher of the glass.
- the lens mold produced according to Reference Aspect A can be an astigmatic power lens mold.
- the glass material to be molded formed in Reference Aspect A is a glass whose bottom surface is spherical, flat or aspherical with central symmetry, glass whose top and bottom surfaces are spherical, or glass having any one of the above shapes. Further, the glass can contain an astigmatism component (toric) on the upper surface.
- toric astigmatism component
- a spectacle lens having a toric surface there is a lens for correcting astigmatism in addition to a double-sided aspherical progressive-power lens as described in aspect II.
- These spectacle lenses having a toric surface have two points at which the curvature becomes maximum at symmetrical positions on the main meridian. At the point of maximum curvature, the curve is deepest on the main meridian.
- the molding surface of the mold for forming such a toric surface also has two points on the axis corresponding to the main meridian that have the maximum curvature at symmetrical positions.
- the molding surface of the molding die for molding the mold molding surface by the hot droop molding method two points on the axis corresponding to the main meridian are maximized on the axis corresponding to the main meridian, It has a symmetrical position. That is, on the mold forming surface, there are two axes at which the curvature is maximum and an axis having a symmetrical position with respect to the geometric center. Therefore, as described in the aspect II, the present inventors utilize the shape feature and use a continuous heating furnace in which a molding die having the molding surface on which the glass material to be molded is disposed is disposed on both sides.
- the molding surface can be easily formed by controlling deformation due to heat softening by passing the inside through the inside so that the axis is substantially perpendicular to the conveying direction.
- a continuous heating furnace having a temperature distribution such that the temperature increases from the inlet to the outlet
- the conveyance direction side high temperature side
- the timing of close contact with the molding surface varies greatly depending on the position of the lower surface of the glass material, and astigma that is unnecessary for spectacle correction occurs, or the error from the design value becomes asymmetrical and the wearing feeling of the glasses decreases. There are things to do.
- a continuous heating furnace is provided with a region where heat sources are arranged on both sides, and the molding die is conveyed to this region so that the axis and the conveying direction are substantially orthogonal to each other, the greatest deformation should occur.
- the portion can be heated evenly on the left and right, and the timing of close contact between the lower surface of the glass material and the molding surface can be made uniform in each part of the surface.
- Reference embodiment A was completed based on the above findings. According to the reference aspect A, a spectacle lens mold capable of forming an astigmatism correcting lens having excellent wearing feeling can be manufactured with high productivity.
- the virtual straight line is preferably specified based on the astigmatic axis of the prescription value.
- the optical surface of the spectacle lens generally has a non-centrosymmetric shape except for a single focus lens composed only of spherical refractive power.
- a lens including a toric component has symmetry with respect to a straight line passing through the optical center (hereinafter also referred to as having axial symmetry).
- the necessary size of the toric component is appropriately determined depending on the degree of astigmatism.
- the astigmatism magnitude and the astigmatism axis direction are included in the prescription value, and can be specified and referred to in the prescription when the lens is ordered.
- the astigmatism refractive power and the direction of the astigmatism axis differ for each lens order.
- the maximum and minimum axis directions of the lens surface curvature are in the toric axis direction regardless of the size of the toric component. Only depends.
- the maximum and minimum axial directions can be specified by referring to the prescription. For example, when the astigmatic refractive power of the prescription value is negative, the astigmatic axis direction has the maximum radius of curvature.
- the axial direction having the minimum radius of curvature is a direction orthogonal to the astigmatic axis. Therefore, the axial direction in which the deformation amount of the glass material is large as the shape of the mold can be specified as the direction orthogonal to the astigmatic axis of the prescription value.
- the astigmatic refractive power display of the prescription value is +
- the direction coinciding with the astigmatic axis of the prescription value is the axial direction having the minimum radius of curvature. Therefore, as the shape of the mold, the axial direction in which the amount of deformation of the glass material is large can be specified as the direction that coincides with the astigmatic axis of the prescription value.
- the mold can be arranged in the transport direction or in the direction perpendicular to the transport direction.
- Reference Aspect A After forming the glass optical surface, the glass material can be removed from the mold and a molded product can be obtained.
- the molded product thus obtained can be used as a spectacle lens having a toric surface, preferably a spectacle lens for correcting astigmatism, and more preferably a mold for an astigmatic power lens.
- a part such as a peripheral portion can be removed and used as a spectacle lens mold.
- the lens mold for correcting astigmatism can be easily manufactured with high productivity.
- the temperature measurement position was set so that the preform peripheral part at the center and the outer peripheral side was 10 mm inside from the outer periphery, and the minimum number was set as the electric furnace outlet side.
- the sensor of the number 16 which is not shown in FIG. 12 is a sensor for room temperature measurement. Insert the normal mass production input into the electric furnace with the sensor as described above, and place dummy ceramic molds before and after the sensor position, then control the inside of the furnace to the temperature distribution shown in the specific embodiment above The electric furnace was operated.
- FIG. 13 shows an electric furnace layout.
- FIG. 14 shows temperature measurement (center part) deviation results measured by the sensors of Nos. 11, 12, 13, and 14.
- the center temperature of each of the six preforms in the lateral direction was suppressed to ⁇ 5 ° C. in the range of 600 ° C. or higher, and the range of temperature increase from the glass transition temperature Tg (485 ° C.) to the maximum temperature.
- Tg glass transition temperature
- a difference of about ⁇ 15 ° C. was observed.
- the traveling direction side was 15 ° C. higher than Tg and the traveling direction side was 5 ° C. lower on average around the maximum temperature with the traveling direction of the electric furnace as the axis.
- FIG. 15 shows the results of measuring the temperature of all six preforms in the lateral direction and evaluating the temperature distribution in the direction perpendicular to the traveling direction on the lens in the electric furnace.
- the temperature difference before and after the traveling direction on the preform was the largest in the heating temperature raising step, and the temperature difference was reduced at the highest temperature equal to or higher than Tg as the final stage of the heating temperature raising step.
- the temperature difference became 0 at the initial stage of the low temperature holding step, and the temperature on the side of the one-turn traveling direction became low. Thereafter, the temperature difference state was maintained from the low-speed cooling step to the rapid cooling step.
- Example 1 Molding of two types of glass preforms with a double-sided spherical surface and the same thickness in the normal direction, corresponding to a double-sided aspherical progressive-power lens having a composite surface of a toric surface, a distance portion, and a progressive surface including a near portion It was arrange
- the angle formed by the straight line corresponding to the astigmatic axis of the toric surface of the molding die forming surface and the conveying direction was 90 °.
- the temperature control in the electric furnace was performed in the same manner as the above-described specific mode.
- suction from the mold and 180 ° reversal of the mold were performed.
- the shape error (measured value ⁇ design value) from the design value of the upper surface shape of the glass material discharged out of the furnace was measured by Talysurf. The results are shown in FIG.
- Example 1 the error amount was 0.03D or less, and the absolute amount of error could be reduced. Further, in the embodiment, the symmetry of the error distribution is maintained. By maintaining the symmetry of the error amount in lens manufacturing, it is possible to suppress the occurrence of stigma that is unnecessary for correcting glasses. At the same time, it is possible to reduce the uncomfortable feeling in the spectacle lens wearing state caused by the asymmetry of the error amount. On the other hand, as shown in FIG. 17, in Comparative Example 1, no symmetry was found in the error, and the error amount was large.
- a progressive-power lens mold more specifically, a double-sided aspherical progressive-power lens mold can be easily manufactured with high productivity.
- An explanatory view of a hot droop forming method is shown.
- An example (cross-sectional view) of glass having substantially the same thickness in the normal direction is shown.
- molding die molding surface and the position equivalent to the near measurement reference point is shown.
- the layout in the electric furnace when confirming the temperature distribution in the continuous heating furnace is shown.
- the confirmation result temperature measurement (center part) deviation result) of the temperature distribution in the continuous heating furnace is shown.
- the confirmation result temperature distribution in the direction orthogonal to the traveling direction and the traveling direction) of the temperature distribution in the continuous heating furnace is shown.
- molded in Example 1 is shown.
- molded in the comparative example 1 is shown.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
- Eyeglasses (AREA)
Abstract
Description
眼鏡レンズ用ガラスモールドの成形方法としては、機械的研削研磨法や、機械的研削法や放電加工等の電気的加工法により作成した耐熱性母型を用い、これにガラスブランクスを接触加熱軟化させて母型の面形状を転写する方法等、得ようとする面形状ごとに研削プログラムを用いたり、対応する面形状を有する母型を成形する方法が採用されている。
そこで本発明の目的は、連続式加熱炉を使用した熱垂下成形法によって、優れた装用感を有する眼鏡レンズを成形可能な眼鏡レンズ用鋳型を提供することにある。
多焦点眼鏡レンズの中でも、屈折力が上部から下部へ向かって連続的に変化する累進面を有する累進屈折力レンズは、遠近両用レンズとして広く使用されている。上記累進面では、近用部では曲率が大きく(カーブが深く)、遠用部では曲率が小さい(カーブが浅い)。従って、累進面を形成するためのモールドの成形面も、近用部成形部では曲率が大きく、遠用部成形部では曲率が小さくなる。更には、熱垂下成形法により上記モールド成形面を成形するための成形型の成形面においても、モールド成形面の近用部成形部に対応する部分では曲率が大きく、遠用部成形部に対応する部分では曲率が小さくなる。
そこで本発明者らは、この形状的特徴および連続式加熱炉における加熱の不均一性を利用し、連続式加熱炉内の成形型搬送方向に向かって温度が上昇する領域において、近用部成形部相当側が前方、遠用部成形部相当側が後方となるように成形型(成形面上にガラス素材が配置されている)を搬送することにより、加熱軟化による変形を制御し、モールド成形面を容易に形成できることを新たに見出した。これは、熱垂下成形法により累進面を形成する場合、近用部成形側の変形量は大きく、遠用部成形側の変形量は小さいため、大きく変形させるべき近用部成形部相当側を高温側へ配置することにより、炉内の温度分布を利用し変形量を制御できるからである。
本発明は、以上の知見に基づき完成された。
前記連続式加熱炉を、成形型搬送方向に向かって温度が上昇する温度分布を有する昇温領域が含まれるように温度制御すること、
前記成形型として、成形面上で曲率分布を有する成形型を使用すること、ならびに、
上記昇温領域において、成形型の搬送方向と直交し、かつ成形面の幾何中心を通過する仮想直線によって二分される搬送方向側の部分に成形面上で曲率が最大となる部分が含まれるように成形型を搬送すること、
を含む前記製造方法
に関する。
本発明は、被成形ガラス素材を成形面上に配置した成形型を連続式加熱炉内へ導入し、該炉内を搬送しながら加熱処理を施すことにより、上記被成形ガラス素材の上面を、累進面を含む面を形成するための成形面形状に成形する、レンズ用鋳型の製造方法(以下、「態様I」ともいう)に関する。態様Iは、連続式加熱炉を、成形型搬送方向に向かって温度が上昇する温度分布を有する昇温領域が含まれるように温度制御すること、前記成形型として、成形面上で曲率分布を有する成形型を使用すること、ならびに、上記昇温領域において、成形型の搬送方向と直交し、かつ成形面の幾何中心を通過する仮想直線によって二分される搬送方向側の部分に成形面上で曲率が最大となる部分が含まれるように成形型を搬送すること、を含む。
図1に、熱垂下成形法の説明図を示す。
通常、熱垂下成形法では、被成形ガラス素材を、ガラス素材下面中央部と成形型成形面が離間した状態となるように成形型上に配置した状態(図1(a))で加熱処理を施す。これにより、被成形ガラス素材の下面は自重により変形し成形型成形面と密着し(図1(b))、成形型成形面形状がガラス素材上面に転写され、その結果、ガラス素材上面を所望形状に成形することができる。製造された鋳型は、注型重合法によりプラスチックレンズを製造するための成形型の上型または下型として使用することができる。より詳しくは、熱垂下成形法により成形されたガラス素材上面が成形型内部に配置されるように、上型および下型をガスケット等により組み合わせて成形型を組み立て、この成形型のキャビティへプラスチックレンズ原料液を注入し重合反応を行うことにより、累進面を有するレンズを得ることができる。
そこで態様Iでは、連続式加熱炉を、成形型搬送方向に向かって温度が上昇する温度分布を有する昇温領域が含まれるように温度制御するとともに、上記昇温領域において、成形型の搬送方向と直交し、かつ成形面の幾何中心を通過する仮想直線によって二分される搬送方向側の部分に、成形面上で曲率が最大となる部分、即ち成形面と密着させるためには大きく変形させる必要がある部分が含まれるように成形型を搬送する。前述の特開昭63-306390号公報に記載の方法では、連続式加熱炉内の温度分布による加熱の不均一性への対策として、加熱状態が均一となるように加熱対象物を回転させていたのに対し、態様Iでは連続式加熱炉内の加熱の不均一性を利用し、同一加熱対象物における加熱変形量を意図的に変えることにより、連続式加熱炉を使用し累進屈折力レンズ用鋳型を生産性よく量産することができる。
前記成形型として、面内に曲率分布を有し、かつ幾何中心を通過する仮想直線上に、該直線上で曲率が最大となる点を2点、幾何中心からの距離が略等しい対向する位置に有する成形面を有する成形型を使用すること、
前記連続式加熱炉として、両側面に熱源が配置された側方加熱領域を含む連続式加熱炉を使用し、かつ前記連続式加熱炉を、成形型搬送方向に向かって温度が上昇する温度分布を有する昇温領域が含まれるように温度制御すること、
上記側方加熱領域において、成形型搬送方向が上記仮想直線と略直交するように成形型を搬送すること、および、
上記昇温領域において、成形型の搬送方向と直交し、かつ上記仮想直線によって二分される搬送方向側の部分に成形面上で曲率が最大となる部分が含まれるように成形型を搬送すること、
を更に含む。
一方、上記眼鏡レンズは、トーリック面において主経線上の対称の位置に、曲率が最大となる点を2点有する。主経線上で曲率が最大となる点では、主経線上で最もカーブが深くなる。このようなトーリック面を形成するためのモールドの成形面も、主経線に対応する軸上に、曲率が最大となる点を2点、対称の位置に有する。更には、熱垂下成形法により上記モールド成形面を成形するための成形型の成形面においても、モールド成形面と同様に主経線に対応する軸上に、曲率が最大となる点を2点、対称の位置に有する。即ち、上記成形型成形面では、曲率が最大となる点を2点、幾何中心を基準として対称の位置に有する軸が存在する。
更に本発明者らは、トーリック面形成用の成形型成形面の形状的特徴を利用し、被成形ガラス素材を配置した成形型を、両側面に熱源を配置した連続式加熱炉内に、上記主経線に対応する軸が搬送方向とほぼ直交するように通過させることにより、加熱軟化による変形を制御し、モールド成形面を容易に形成できることを新たに見出した。例えば入口から出口に向かって高温となるような温度分布を有する連続式加熱炉内で、被成形ガラス素材を上記形状の成形面上に配置して成形しようとすると、搬送方向側(高温側)ほど早く変形するため、ガラス素材下面の位置によって成形型成形面と密着するタイミングが大きく異なり、眼鏡矯正に不要なアスティグマが発生したり、設計値からの誤差が非対称となり眼鏡の装用感が低下することがある。これに対し、連続式加熱炉内に両側面に熱源を配置した領域を設けた上で、この領域に上記軸と搬送方向がほぼ直交するように成形型を搬送すれば、大きく変形させるべき部分を左右均等に加熱することができ、ガラス素材下面と成形型成形面との密着のタイミングを面内各部で揃えることができる。
態様IIは、以上の知見に基づき完成された。
態様IIでは、上記複合面を形成するための成形面を有する成形型において、軸対称性を有する曲率の最大方向と、対称性がない最大曲率をそれぞれ特定し、前記特定された基準位置に対応して成形型の搬送方向を決定する。搬送方法の詳細は後述する。
そこで態様IIでは、成形型成形面の対称性を利用し、連続式加熱炉内に両側面に熱源を配置した領域を設け、この領域での成形型搬送方向が上記仮想直線と略直交するように成形型を搬送する。これにより、同一軸上で大きく変形させるべき2箇所を均等に加熱変形することが可能となる。
本発明において連続式加熱炉内を通過させることにより上面を成形するガラス素材は、成形型成形面と密着させるべき下面の形状が球面、平面または中心対称性を有する非球面であるガラス素材が好適である。これは、例えば球面形状のガラス素材下面は、面内で曲率が一定であるため、面内で曲率が異なる成形型成形面と密着させる際、面内での変形量の違いが特に顕在化するからである。ガラス素材下面が平面および中心対称性を有する非球面の場合も同様である。このような場合であっても、先に説明したように本発明によれば、連続式加熱炉内においてガラス素材の加熱変形量を制御することができる。更に、被ガラス成形素材としては、前記形状の下面を有するとともに上面に乱視成分(トーリック)を含むガラス素材も好適である。
ガラス素材両面の法線方向とは、ガラス素材表面上の任意の位置でガラス素材表面となす角度が垂直である方向を示す。従って法線方向は面上の各位置によって変化する。例えば図2の方向204はガラス素材凹面上の点208における法線方向を表し、法線方向204が凹凸面となす交点がそれぞれ208および209となるため、208と209との間隔が、法線方向の厚みとなる。一方、他のガラス凹面上の位置として例えば210や212があり、その法線方向はそれぞれ方向203と方向205である。法線方向203上では210と211の間隔が、法線方向205では212と213の間隔が、法線方向の厚みとなる。法線方向に等厚なガラス素材では、このように上下面の法線方向間隔が同一の値となる。つまり、法線方向に等厚なガラス素材では、上下面が同一の中心(図1中の207)を共有する球面の一部となる。
通常、連続式加熱炉の熱源は、加熱対象物搬送経路の上方および/または下方に設けられる。これに対し、本発明では、連続式加熱炉内に、両側面に熱源が配置された領域(側方加熱領域)を設けることができる。この領域は、少なくとも、ガラスの軟化変形が進行する領域とすることが好ましく、被成形ガラス素材を該ガラスのガラス転移温度以上に加熱する領域であることが更に好ましい。本発明では、連続式加熱炉を、入口から出口に向かって、昇温領域、定温保持領域、冷却領域、がこの順に位置するように温度制御することが好ましい。上記一連の領域を通過させることによりガラス素材の加熱処理を連続的に行うことができる。この場合、側方加熱領域は、少なくとも昇温領域とすることができ、好ましくは昇温領域および定温保持領域とすることができ、更に好ましくは昇温領域、定温保持領域および冷却領域を含む炉内全領域とすることができる。
本発明では、連続式加熱炉内の成形型搬送方向に向かって温度が上昇する温度部分を有する昇温領域において、成形型の搬送方向と直交し、かつ成形面の幾何中心を通過する仮想直線によって二分される搬送方向側の部分に成形面上で曲率が最大となる部分が含まれるように成形型を搬送する。このようにガラス素材を、最も大きく変形させるべき部分が炉内の高温側に位置するように搬送することにより、成形面とガラス素材下面と密着のタイミングのばらつきを低減し、変形を制御することが可能となる。ガラス素材下面と成形面とが密着するタイミングが面内各部において大きく異なると、眼鏡矯正に不要なアスティグマが発生したり、設計値からの誤差が非対称となり眼鏡の装用感が低下することがあるのに対し、本発明によれば優れた装用感を有する眼鏡レンズを成形可能な鋳型を得ることができる。
眼鏡レンズの屈折率を測定する基準点として、JIS T7315、JIS T7313またはJIS T7330に屈折力測定基準点が規定されている。屈折力測定基準点は、眼鏡レンズの物体側または眼球側の面上の例えば直径8.0~8.5mm程度の円で囲まれる部分である。本発明により製造される鋳型によって成形可能な眼鏡レンズには、遠用部測定基準点と近用部測定基準点という2つの屈折力測定基準点が存在する。累進屈折力レンズの遠用部測定基準点と近用部測定基準点の間に位置する中間領域は累進帯と呼ばれ、屈折力が累進的に変化している。さらに近用部測定基準点は主子午線から左右いずれかの位置の眼球の輻輳に相当する位置に配置されており、眼球の左右区分に応じて主子午線の左右いずれに配置されるかが決定される。熱垂下成形法によりガラス素材が成形され鋳型となった場合、該鋳型では、ガラス素材上面(成形面と密着した面とは反対の面)であった面が眼鏡レンズに転写される。成形型成形面の「屈折力測定基準点に相当する位置」とは、製造される鋳型表面において眼鏡レンズの屈折力測定基準点に転写される部分となるガラス素材上面の部分に、好ましくは法線方向において対向するガラス素材下面に密着する部分をいうものとする。成形型成形面上の「遠用部測定基準点に相当する位置」および「近用部測定基準点に相当する位置」の配置例を図3に示す。
以下に、方法1について説明する。
図4に示すように成形型成形面の幾何中心を通り端と端を結んだ直線上の3点AOBの座標値を使用してその断面における近似曲率半径を、円の式の連立方程式から算出する。計算に使用する3点をA(X1,Y1)、O(X2,Y2)、B(X3,Y3)とすると図4に示すように、ZX断面の座標値は、A(X1,Z1)、O(X2,Z2)、B(X3,Z3)となる。この3点AOBを通る円の式を求めるには、以下の連立方程式を解く。ただし、この3点がZX断面において直線上にないいことが必要条件となる。a、bをそれぞれ円の中心のX、Z座標値、rは円の半径とすると、連立方程式は下記式2となる。
図8に示すように、成形型成形面の幾何中心を通り端と端を結んだ直線上の3点以上の座標値を使用してその断面における近似曲率半径を円の式に最小二乗法で近似して算出する。図8中のA~I点のように3点以上のn個の点で計算に使用する座標点を(X1,Y1),(X2,Y2),・・・,(Xn,Yn)とすると、図8に示すようにZX断面の座標値は(X1,Z1),(X2,Z2),・・・,(Xn,Zn)となる。このn個の座標値に最も近い円の式を求めるには最小二乗法を使用して下記式5の連立方程式を解く。ただし、この全ての点がZX断面において直線上にないことを条件とする。式5中、a、bはそれぞれ円の中心のX、Z座標値、rは円の半径とする。
次に、連続式加熱炉の温度制御について説明する。
連続式加熱炉とは、入口と出口を有しており、コンベアー等の搬送装置によって設定された温度分布の炉内に被加工物を一定時間で通過させて熱処理を行う装置である。連続式加熱炉では、発熱と放熱を考慮した複数のヒーターと炉内空気循環の制御機構によって、炉内部の温度分布を制御することができる。通常、ヒーターは炉内搬送経路の上部および下部に設置されるが、前述のように本発明では少なくとも一部に、両側面に熱源を配置した領域を設けることができる。
PID制御を用いることにより、投入された処理物形状および数量による熱量分布の変化に対する炉内温度の温度制御精度を高くすることができる。また電気炉内における搬送は、無摺動方式(例えばウォーキングビーム)を採用することができる。
上記では、少なくとも3点が接触点(支持点)となる態様について説明したが、4点以上で接触(支持)することももちろん可能である。
以下に、17時間を1サイクルとする温度制御の一例を説明する。但し、本発明は以下に示す態様に限定されるものではない。
被成形ガラス素材を成形面上に配置した成形型を連続式加熱炉内へ導入し、該炉内を搬送しながら加熱処理を施すことにより、上記被成形ガラス素材の上面をトーリック面を形成するための成形面形状に成形する、トーリック面を有するレンズ用鋳型の製造方法であって、
前記成形型として、幾何中心を通過する仮想直線上に、該直線上で曲率が最大となる点を2点、幾何中心からの距離が略等しい対向する位置に有する成形面を有する成形型を使用すること、および、
前記連続式加熱炉として、両側面に熱源が配置された領域(側方加熱領域)を含む連続式加熱炉を使用し、かつ、上記領域において、成形型搬送方向が上記仮想直線と略直交するように成形型を搬送すること、
を含む前記製造方法。
トーリック面を有する眼鏡レンズとしては、態様IIについて説明したような両面非球面型累進屈折力レンズのほかに、乱視矯正用レンズがある。これらトーリック面を有する眼鏡レンズは、主経線上の対称の位置に、曲率が最大となる点を2点有する。曲率が最大となる点では、主経線上で最もカーブが深くなる。このようなトーリック面を形成するためのモールドの成形面も、主経線に対応する軸上に、曲率が最大となる点を2点、対称の位置に有する。更には、熱垂下成形法により上記モールド成形面を成形するための成形型の成形面においても、モールド成形面と同様に主経線に対応する軸上に、曲率が最大となる点を2点、対称の位置に有する。即ち、上記成形型成形面では、曲率が最大となる点を2点、幾何中心を基準として対称の位置に有する軸が存在する。
そこで本発明者らは、態様IIについて説明したように、この形状的特徴を利用し、被成形ガラス素材を配置した上記成形面を有する成形型を、両側面に熱源を配置した連続式加熱炉内を、上記軸が搬送方向とほぼ直交するように通過させることにより、加熱軟化による変形を制御し、モールド成形面を容易に形成できることを新たに見出した。例えば入口から出口に向かって高温となるような温度分布を有する連続式加熱炉内で、被成形ガラス素材を上記形状の成形面上に配置して成形しようとすると、搬送方向側(高温側)ほど早く変形するため、ガラス素材下面の位置によって成形型成形面と密着するタイミングが大きく異なり、眼鏡矯正に不要なアスティグマが発生したり、設計値からの誤差が非対称となり眼鏡の装用感が低下することがある。これに対し、連続式加熱炉内に両側面に熱源を配置した領域を設けた上で、この領域に上記軸と搬送方向がほぼ直交するように成形型を搬送すれば、最も大きく変形させるべき部分を左右均等に加熱することができ、ガラス素材下面と成形型成形面との密着のタイミングを面内各部で揃えることができる。参考態様Aは、以上の知見に基づき完成された。参考態様Aによれば、優れた装用感を有する乱視矯正用レンズを成形可能な眼鏡レンズ用鋳型を高い生産性をもって製造することができる。
炉内全域にわたって上下両側面に板状のヒーターを配置した連続式加熱炉内でのガラス素材の温度分布の評価を下記条件にて行った。
内部に横方向に2列、縦方向に54タクトを有し、横方向の2列には耐熱ステンレスの上に各3個のセラミックス型とプリフォーム(ガラス素材)を載せることができる電気炉を使用した。それぞれについて、各プリフォーム表面上に最大4方向と中心の温度分布測定を行った。搬送系に問題のないと思われる最大数のセンサー19本を用いて測定を行った。図12に、横方向のセンサーレイアウトを示す。測温位置は中心と外周側のプリフォーム周辺部は外周より10mm内側とし、最小番号を電気炉出口側として配置した。尚、図12中、図示しない番号16のセンサーは、室温測定用センサーである。
上記のようにセンサーを配置した電気炉に、通常量産投入時を挿入し、センサー位置の前後にはダミーのセラミックス型を配置した後、炉内を前述の具体的態様に示した温度分布に制御し電気炉を稼動させた。図13に、電気炉内レイアウトを示す。
両面球面で法線方向に等厚な2種類のガラスプリフォームを、トーリック面と遠用部と近用部を含む累進面との複合面を有する両面非球面型累進屈折力レンズに対応する成形面を有する成形型の成形面上に配置した。次いで、プリフォームを配置した成形型を、成形面の幾何中心から周縁部へ向かって平均曲率が最大となる方向が搬送方向と一致するように電気炉内へ導入し炉内で搬送した。この状態で、成形型成形面の、トーリック面の乱視軸に相当する直線と搬送方向とのなす角度は、90°であった。電気炉内の温度制御は前述の具体的態様と同様にした。定温保持工程中、プリフォームの温度がTgを超えた時点で成形型からの吸引および成形型の180°反転を行った。炉外へ排出されたガラス素材の上面形状の設計値からの形状誤差(測定値-設計値)をタリサーフによって測定した。結果を図16に示す。
電気炉導入時の成形型の向きを180°変えた点以外は実施例1と同様の2種類のガラスプリフォームの加熱成形を行った。実施例1と同様に炉外へ排出されたガラス素材の上面形状の設計値からの形状誤差を測定した。結果を図17に示す。
これに対し、図17に示すように比較例1では誤差に対称性がみられず、誤差量も大きかった。
Claims (12)
- 被成形ガラス素材を成形面上に配置した成形型を連続式加熱炉内へ導入し、該炉内を搬送しながら加熱処理を施すことにより、上記被成形ガラス素材の上面を、累進面を含む面を形成するための成形面形状に成形する、レンズ用鋳型の製造方法であって、
前記連続式加熱炉を、成形型搬送方向に向かって温度が上昇する温度分布を有する昇温領域が含まれるように温度制御すること、
前記成形型として、成形面上で曲率分布を有する成形型を使用すること、ならびに、
上記昇温領域において、成形型の搬送方向と直交し、かつ成形面の幾何中心を通過する仮想直線によって二分される搬送方向側の部分に成形面上で曲率が最大となる部分が含まれるように成形型を搬送すること、
を含む前記製造方法。 - 前記昇温領域における搬送は、成形面の幾何中心から周縁部へ向かって平均曲率が最大となる方向が搬送方向と略等しくなるように行われる請求項1に記載の製造方法。
- 前記連続式加熱炉を、成形型導入口側から、前記昇温領域、定温保持領域、および冷却領域がこの順に配置されるように温度制御する請求項1または2に記載の製造方法。
- 上記昇温領域において、成形型を回転揺動することを含む請求項1~3のいずれか1項に記載の製造方法。
- 上記回転揺動における揺動角度および振幅は、前記レンズの加入屈折力および/またはインセット量に基づき決定される請求項4に記載の製造方法。
- 前記回転揺動における揺動角度は搬送方向を基準として±5~45°の範囲であり、かつ振幅は0.01~1Hzの範囲である請求項4または5に記載の製造方法。
- 前記定温保持領域において、成形型の搬送方向と直交し、かつ成形面の幾何中心を通過する仮想直線によって二分される搬送方向側と反対側の部分に成形面上で曲率が最大となる部分が含まれるように成形型を回転することを含む請求項3~6のいずれか1項に記載の製造方法。
- 前記定温保持領域において搬送される成形型上に配置された被成形ガラス素材の温度は、該ガラスのガラス転移温度以上の温度である請求項3~7のいずれか1項に記載の製造方法。
- 前記累進面を含む面は、トーリック面と累進面との複合面であり、
前記成形型は、前記仮想直線上に、該直線上で曲率が最大となる点を2点、幾何中心からの距離が略等しい対向する位置に有し、
前記連続式加熱炉として、両側面に熱源が配置された側方加熱領域を含む連続式加熱炉を使用すること、および、
上記側方加熱領域において、成形型搬送方向が上記仮想直線と略直交するように成形型を搬送すること、
を更に含む請求項1~8のいずれか1項に記載の製造方法。 - 前記側方加熱領域は、被成形ガラス素材を該ガラスのガラス転移温度以上に加熱する領域である請求項9に記載の製造方法。
- 前記被成形ガラス素材として、下面が球面、平面または中心対称性を有する非球面であるガラスを使用する請求項1~10のいずれか1項に記載の製造方法。
- 前記被成形ガラス素材として、上面および下面が球面であるガラスを使用する請求項11に記載の製造方法。
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/677,699 US20110304064A1 (en) | 2008-01-31 | 2008-11-25 | Method of manufacturing lens casting mold |
JP2009551402A JP5319555B2 (ja) | 2008-01-31 | 2008-11-25 | レンズ用鋳型の製造方法 |
EP08871636.0A EP2248646A4 (en) | 2008-01-31 | 2008-11-25 | METHOD FOR MANUFACTURING MOLD FOR LENS |
CN2008801259590A CN101965256B (zh) | 2008-01-31 | 2008-11-25 | 透镜用铸型的制造方法 |
BRPI0822108-1A BRPI0822108A2 (pt) | 2008-01-31 | 2008-11-25 | Método para fabricar um molde de moldagem de lente |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2008-020860 | 2008-01-31 | ||
JP2008-020875 | 2008-01-31 | ||
JP2008020860 | 2008-01-31 | ||
JP2008020921 | 2008-01-31 | ||
JP2008020875 | 2008-01-31 | ||
JP2008-020921 | 2008-01-31 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2009096085A1 true WO2009096085A1 (ja) | 2009-08-06 |
Family
ID=40912445
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2008/071352 WO2009096085A1 (ja) | 2008-01-31 | 2008-11-25 | レンズ用鋳型の製造方法 |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP2248646A4 (ja) |
JP (1) | JP5319555B2 (ja) |
CN (1) | CN101965256B (ja) |
BR (1) | BRPI0822108A2 (ja) |
WO (1) | WO2009096085A1 (ja) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2010098136A1 (ja) * | 2009-02-27 | 2010-09-02 | Hoya株式会社 | レンズ用鋳型の製造方法および眼鏡レンズの製造方法 |
EP2402133A1 (en) * | 2009-02-27 | 2012-01-04 | Hoya Corporation | Method of producing mold for lens and method of producing eyeglass lens |
US8197727B2 (en) | 2005-11-30 | 2012-06-12 | Hoya Corporation | Method of manufacturing formed article, covering member, and forming apparatus comprising the same |
US8277704B2 (en) | 2005-11-18 | 2012-10-02 | Hoya Corporation | Method of manufacturing formed article, mold and method of manufacturing the same |
JP2013237261A (ja) * | 2012-03-26 | 2013-11-28 | Hoya Corp | モールド用成形型、モールド及び眼鏡レンズの製造方法 |
US9242889B2 (en) | 2005-11-18 | 2016-01-26 | Hoya Corporation | Method of manufacturing formed article, glass material, and method of determining shape of glass material and mold |
US9242888B2 (en) * | 2011-04-21 | 2016-01-26 | Hoya Corporation | Manufacturing method of glass blank for magnetic disk, manufacturing method of glass substrate for magnetic disk, glass blank for magnetic disk, glass substrate for magnetic disk, and magnetic disk |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP6106035B2 (ja) * | 2012-06-29 | 2017-03-29 | Hoya株式会社 | ガラス塊の製造装置、ガラス塊の製造方法、ガラス成形品の製造方法及び光学素子の製造方法 |
CN104297943B (zh) * | 2014-10-09 | 2017-09-05 | 河南工业职业技术学院 | 光学玻璃渐进多焦点镜片及其制作方法和应用 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS63306390A (ja) | 1987-06-03 | 1988-12-14 | 日本特殊陶業株式会社 | 熱処理方法 |
JPH10291828A (ja) * | 1997-04-21 | 1998-11-04 | Asahi Glass Co Ltd | ガラス板の成形装置 |
WO2006095007A1 (fr) * | 2005-03-10 | 2006-09-14 | Glaverbel | Procede de bombage de feuilles de verre |
WO2007058353A1 (ja) | 2005-11-18 | 2007-05-24 | Hoya Corporation | 成形品の製造方法、ガラス素材、ならびにガラス素材および成形型の面形状決定方法 |
WO2007063735A1 (ja) * | 2005-11-30 | 2007-06-07 | Hoya Corporation | 成形品の製造方法、閉塞部材およびそれを含む成形装置 |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5147437A (en) * | 1988-07-25 | 1992-09-15 | Bristol Alexander C | Invisible flat-top mold blank and method for manufacturing same |
JPH04275930A (ja) * | 1991-02-26 | 1992-10-01 | Asahi Optical Co Ltd | 熱軟化性物質の熱垂下成形方法及び成形装置 |
JPH06130333A (ja) * | 1992-10-20 | 1994-05-13 | Toray Ind Inc | 多焦点眼鏡レンズ用ガラスモールドの製造方法 |
JPH1149528A (ja) * | 1997-06-06 | 1999-02-23 | Minolta Co Ltd | ガラス素子の成形方法 |
-
2008
- 2008-11-25 JP JP2009551402A patent/JP5319555B2/ja not_active Expired - Fee Related
- 2008-11-25 EP EP08871636.0A patent/EP2248646A4/en not_active Withdrawn
- 2008-11-25 BR BRPI0822108-1A patent/BRPI0822108A2/pt not_active IP Right Cessation
- 2008-11-25 WO PCT/JP2008/071352 patent/WO2009096085A1/ja active Application Filing
- 2008-11-25 CN CN2008801259590A patent/CN101965256B/zh not_active Expired - Fee Related
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS63306390A (ja) | 1987-06-03 | 1988-12-14 | 日本特殊陶業株式会社 | 熱処理方法 |
JPH10291828A (ja) * | 1997-04-21 | 1998-11-04 | Asahi Glass Co Ltd | ガラス板の成形装置 |
WO2006095007A1 (fr) * | 2005-03-10 | 2006-09-14 | Glaverbel | Procede de bombage de feuilles de verre |
WO2007058353A1 (ja) | 2005-11-18 | 2007-05-24 | Hoya Corporation | 成形品の製造方法、ガラス素材、ならびにガラス素材および成形型の面形状決定方法 |
WO2007063735A1 (ja) * | 2005-11-30 | 2007-06-07 | Hoya Corporation | 成形品の製造方法、閉塞部材およびそれを含む成形装置 |
Non-Patent Citations (1)
Title |
---|
See also references of EP2248646A4 * |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8277704B2 (en) | 2005-11-18 | 2012-10-02 | Hoya Corporation | Method of manufacturing formed article, mold and method of manufacturing the same |
US9242889B2 (en) | 2005-11-18 | 2016-01-26 | Hoya Corporation | Method of manufacturing formed article, glass material, and method of determining shape of glass material and mold |
US8197727B2 (en) | 2005-11-30 | 2012-06-12 | Hoya Corporation | Method of manufacturing formed article, covering member, and forming apparatus comprising the same |
WO2010098136A1 (ja) * | 2009-02-27 | 2010-09-02 | Hoya株式会社 | レンズ用鋳型の製造方法および眼鏡レンズの製造方法 |
EP2402133A1 (en) * | 2009-02-27 | 2012-01-04 | Hoya Corporation | Method of producing mold for lens and method of producing eyeglass lens |
US8641937B2 (en) | 2009-02-27 | 2014-02-04 | Hoya Corporation | Method of manufacturing lens casting mold and method of manufacturing eyeglass lens |
EP2402133A4 (en) * | 2009-02-27 | 2014-10-15 | Hoya Corp | DEVICE FOR PRODUCING A FORM FOR A LENS AND METHOD FOR PRODUCING A GLASS GLASS |
JP5615799B2 (ja) * | 2009-02-27 | 2014-10-29 | Hoya株式会社 | レンズ用鋳型の製造方法および眼鏡レンズの製造方法 |
US9242888B2 (en) * | 2011-04-21 | 2016-01-26 | Hoya Corporation | Manufacturing method of glass blank for magnetic disk, manufacturing method of glass substrate for magnetic disk, glass blank for magnetic disk, glass substrate for magnetic disk, and magnetic disk |
JP2013237261A (ja) * | 2012-03-26 | 2013-11-28 | Hoya Corp | モールド用成形型、モールド及び眼鏡レンズの製造方法 |
US9676157B2 (en) | 2012-03-26 | 2017-06-13 | Hoya Corporation | Manufacturing method for mold die, mold and eyeglass lens |
Also Published As
Publication number | Publication date |
---|---|
EP2248646A1 (en) | 2010-11-10 |
CN101965256B (zh) | 2013-11-13 |
JP5319555B2 (ja) | 2013-10-16 |
JPWO2009096085A1 (ja) | 2011-05-26 |
EP2248646A4 (en) | 2014-10-01 |
BRPI0822108A2 (pt) | 2015-06-30 |
CN101965256A (zh) | 2011-02-02 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5319555B2 (ja) | レンズ用鋳型の製造方法 | |
JP5615799B2 (ja) | レンズ用鋳型の製造方法および眼鏡レンズの製造方法 | |
JP5496179B2 (ja) | レンズ用鋳型の製造方法および眼鏡レンズの製造方法 | |
JP5042032B2 (ja) | 成形品の製造方法、ガラス素材、ならびにガラス素材および成形型の面形状決定方法 | |
CN101312920B (zh) | 成形品的制造方法、玻璃坯料、以及玻璃坯料及成形模型的面形状决定方法 | |
JP5393664B2 (ja) | レンズ用鋳型の製造方法 | |
US20110304064A1 (en) | Method of manufacturing lens casting mold | |
CN101321700B (zh) | 成形品的制造方法、密封部件以及包括其的成形装置 | |
JP2013533190A (ja) | 貼り付けられる成形ガラス物品およびその製造方法 | |
JP5042033B2 (ja) | 成形品の製造方法、保持部材および成形装置 | |
RU2412915C2 (ru) | Способ производства формованного изделия, стекломатериал и способ определения формы стекломатериала и шаблона | |
JP2013227176A (ja) | 光学素子の成形装置及び成形方法 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200880125959.0 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 08871636 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2009551402 Country of ref document: JP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 12677699 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2008871636 Country of ref document: EP |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 5378/CHENP/2010 Country of ref document: IN |
|
ENP | Entry into the national phase |
Ref document number: PI0822108 Country of ref document: BR Kind code of ref document: A2 Effective date: 20100730 |