JP4029576B2 - Manufacturing method of spectacle lens - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a spectacle lens, and more particularly to a method for manufacturing a spectacle lens capable of creating surface shapes of all types of spectacle lenses by machining.
[0002]
[Prior art]
Among the eyeglass lenses, there are currently two main methods of manufacturing plastic lenses: a method of directly molding a finish lens formed on the final optical surface as a spectacle lens by transferring a mold by a casting method, and a casting method. A thick semi-finished lens whose surface is finished to the final optical surface by transfer of the casting mold is molded in advance, and the other surface is cut and polished into a predetermined lens surface shape to create a shape. The final optical surface is used as a method.
[0003]
In addition, spectacle lenses are roughly classified into single focus lenses and multifocal lenses. In the multifocal lens, a progressive multifocal lens having a progressive surface composed of a distance portion, a near portion, and a progressive portion in which the focal length continuously changes between them is the mainstream. A single focus lens mainly has factors such as spherical power, astigmatism power, and lens thickness, and a multifocal lens has factors such as spherical power, astigmatism power, astigmatism axis, addition power, and lens thickness. The combination of these factors becomes extremely large, and especially in a multifocal lens, it becomes a huge number of combinations. Therefore, the method of directly molding the finish lens by the casting method is limited to combinations with many orders, and many plastic lenses are manufactured by machining a semi-finished lens.
[0004]
In the machining of the semi-finished lens, it is necessary to first mold the semi-finished lens in advance. This semi-finished lens is a casting method using two molds, the convex side is created by transferring the mold to the spherical surface of a single focal lens or the progressive surface of a progressive multifocal lens, and the concave side is thicker than the finished dimensions, It is transferred by a mold into a shape that fits a certain range of prescriptions. Then, the concave surface of the semi-finished lens is machined using a so-called curve generator or a generator that can be developed to process a pseudo toric surface. Rough cutting is performed so as to obtain a surface shape and a predetermined thickness. After that, sanding process similar to lapping process is applied to finish the lens surface shape precisely. In this sanding process, the lens held in a dedicated jig is placed on a processing dish made of aluminum or the like with a polishing pad, and the processing dish is pressed firmly against the lens while pouring water onto the lens processing surface. The surface shape of the processing dish is transferred to the lens surface by relatively sliding it. The final lens surface shape with less unevenness can be obtained in the sanding process. Then, using the same apparatus as the sanding process, the surface unevenness is smoothed and mirror polishing is performed to the accuracy that the final optical surface can be obtained.
[0005]
[Problems to be solved by the invention]
However, in recent years, a so-called inner surface progressive multifocal lens has been proposed in which a concave surface on the eyeball side is provided with a progressive surface or a curved surface obtained by combining a progressive surface and a toric surface. This inner surface progressive multifocal lens can reduce fluctuations and distortions, which are disadvantages of the progressive multifocal lens, and can dramatically improve optical performance.
[0006]
However, the curve generator conventionally used for creating a concave surface on the eyeball side, etc. can only process either a spherical surface or a toric surface because of its structure. It is impossible to create a complex curved surface that combines the two. Moreover, in the sanding process, it is impossible to create a complicated curved surface such as a progressive surface because of the principle of transferring the shape of the processing dish by sliding with the processing dish.
[0007]
Therefore, development of a new spectacle lens manufacturing method capable of manufacturing a lens having a complicated curved surface such as an inner surface progressive multifocal lens with high productivity is demanded.
[0008]
The present invention has been made in view of the above demands, and an object of the present invention is to provide a method for manufacturing a spectacle lens capable of manufacturing all spectacle lenses including an inner surface progressive multifocal lens with high productivity.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention performs a lens shape creation process by machining by numerical control (NC), and the shape creation process approximates a spectacle lens substrate to a desired lens surface shape. Performs rough roughing process that approximates the surface shape quickly and then finishes the surface precisely to the desired lens surface shape, thereby synthesizing a progressive surface or progressive surface and toric surface from a simple spherical surface. All lens surface shapes up to complicated free-form surfaces such as curved surfaces can be created with high productivity.
[0010]
The cutting process by numerical control is to synchronize the relative positions of the cutting tool in the X direction and the Y direction with the rotation of the spectacle lens base material while rotating the spectacle lens base material with the rotation axis in the Y direction. With this, all kinds of surface shapes can be created.
[0011]
Using a numerically controlled machine tool that can switch between roughing and finishing tools, a roughing tool is used in the rough machining process, and a single cutting tool is used in the finishing process. A series of shape creation processes can be continuously performed by a machine.
[0012]
Since the lens base material is plastic in the processing of the lens base material, chipping may occur if the processing conditions are not properly selected according to the final shape and material of the lens base material. . Therefore, it is preferable to change the processing conditions according to the relative position of the blade and the spectacle lens substrate.
[0013]
In machining by numerical control, addition of prisms for prescription of spectacle lenses and addition of eccentricity can be handled by simply adding these data to the numerical control processing data without changing any processing jig.
[0014]
In addition, the shape creation process may include outer diameter processing and chamfering processing to reduce the outer diameter of the lens.
[0015]
Furthermore, in the shape creation process in the present invention, a lens surface shape based on prescription data of spectacle lenses can be obtained, but it is preferable to provide a mirror polishing process to finish the final optical surface.
[0016]
Therefore, the invention according to claim 1 is an eyeglass lens having a shape creation step of creating a lens surface shape based on a prescription of an eyeglass lens on the eyeglass lens base material by processing one or both surfaces of the eyeglass lens base material. In the manufacturing method, the shape creation step creates an approximate surface shape that approximates the lens surface shape based on the prescription of the spectacle lens on the spectacle lens base material by machining by numerical control based on the numerical control processing data An approximate machining surface rough cutting step, and a finish cutting step of creating a lens surface shape based on the prescription of the spectacle lens from the approximate surface shape by machining by numerical control based on numerical control machining data, the numerical value The cutting process by control rotates the spectacle lens base material while rotating the spectacle lens base blade and the spectacle lens base. And the relative position of the blade and the spectacle lens substrate in the direction orthogonal to the rotation axis are synchronized with the rotation of the spectacle lens substrate, and at least in the finishing step In the method of manufacturing a spectacle lens, the cutting process is performed while changing the feed pitch of the blade synchronized with the rotation according to the relative position of the spectacle lens base material and the blade changing according to the lens surface shape. Provided is a method for manufacturing a spectacle lens, wherein a feed pitch of the cutting tool at the outer peripheral part and / or the central part of the spectacle lens base material in a finishing cutting step is smaller than other parts.
[0017]
According to a second aspect of the present invention, in the finish cutting step, when the prescription of the spectacle lens substrate is astigmatism 2.00 D or more, the feed pitch of the cutting tool in the central portion of the spectacle lens substrate is the spectacle lens substrate. 2. The method for manufacturing a spectacle lens according to claim 1, wherein the feeding pitch is larger than the feed pitch in the other part.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a method for manufacturing a spectacle lens of the present invention will be described with reference to the drawings.
[0026]
The spectacle lens manufacturing method of the present invention can manufacture spectacle lenses having all kinds of desired lens surface shapes regardless of single focus lenses or multifocal lenses. Examples of the lens surface shape include a spherical surface, a rotationally symmetric aspheric surface, a toric surface, an aspheric astigmatic surface obtained by combining the toric surface and the aspheric surface, a progressive surface, and a curved surface obtained by combining the progressive surface and the toric surface. It is particularly suitable for manufacturing a so-called inner surface progressive multifocal lens in which a concave surface on the eyeball side is provided with a progressive surface or a curved surface obtained by combining a progressive surface and a toric surface. In the following, the manufacture of an inner surface progressive multifocal lens will be mainly described.
[0027]
The spectacle lens manufacturing method of the present invention is based on numerical control based on numerical control processing data for the lens surface shape of either one of the convex surface side (outer surface side), concave surface side (inner surface side) or both surfaces of the spectacle lens substrate. It has a shape creation process to create by machining.
[0028]
FIG. 1 is a flowchart showing an embodiment of a polishing process including a shape creation process in the method for manufacturing a spectacle lens of the present invention. Each process is accompanied by a schematic diagram showing lens processing in that process. As shown in FIG. 1, the polishing process includes a layout process, a blocking process, a shape creation process according to the present invention, a mirror finishing process, a deblocking process, a cleaning process, an inspection process, and the like.
[0029]
Before these polishing processes, the customer's spectacle lens prescription data is input to the host computer via the input means by transmission or direct input from the online terminal, and the prescription data is a lens based on the prescription data by the computer. The shape is designed and processed into numerical control processing data. The numerical control machining data is composed of outer diameter machining data, approximate surface machining roughing machining data, finishing machining data, and chamfering machining data.
[0030]
The outer diameter processing data is processing data for cutting an unnecessary outer peripheral portion of the semi-finished lens to reduce the diameter to a predetermined outer diameter.
[0031]
Approximate surface rough machining data creates an approximate surface shape that approximates the desired lens surface shape by cutting the concave or convex surface of the semi-finished lens to reduce the cutting margin in the next finishing process. At the same time, it is the processing data for cutting the thickness of the semi-finished lens having a considerable thickness and finishing it to a predetermined thickness.
[0032]
As the approximate surface shape, for example, a rough free-form curved surface that is similar to the lens surface shape based on the prescription data of the spectacle lens and slightly thicker than the final lens surface shape, or the final lens surface shape itself. The lens surface shape is calculated. Alternatively, a simple rough surface shape is calculated that slightly increases the allowance but reduces the allowance in the next finishing process. Specifically, when astigmatism is included in the prescription, the coordinates of the lens center in the final lens surface shape, the coordinates of the outer edge in the astigmatic axis direction, and the coordinates of the outer edge in the direction orthogonal to the astigmatic axis direction A toric surface for roughing is calculated so that the minimum finishing margin is obtained for each of the coordinates. On the other hand, if astigmatism is not included in the prescription, the coordinates of the lens center in the final lens surface shape, the coordinates of the thinnest part of the outer periphery, and the thickest of the outer periphery A spherical surface for roughing is calculated so that the minimum finishing allowance is obtained for each of the coordinates of the three positions of the coordinates of the thickened portion. As a result, the approximate surface shape is thicker than the final lens surface shape, for example, by about 0.1 to 5.0 mm, although the cutting margin differs depending on the part.
[0033]
Finishing data is a lens surface based on prescription data for spectacle lenses by cutting out a cutting margin of 0.1 to 5.0 mm from the above-mentioned rough curved free-form surface, toric surface or spherical rough approximate surface shape. This is processing data for creating a precise shape.
[0034]
Further, the chamfering data is processing data for chamfering the edge of the processed surface of the semi-finished lens.
[0035]
The numerical control machining data is transmitted from the computer for calculation to the host computer and stored in the host computer. At the time of processing, it is transmitted from a host computer to a numerically controlled machine tool that performs polishing and stored in a storage device in the numerically controlled machine tool.
[0036]
A semi-finished lens is mainly used as a spectacle lens substrate to be processed. When creating the shape of both surfaces of the lens, a simple cylindrical eyeglass lens substrate may be used. In the semi-finished lens, a gap between two glass molds facing each other with a predetermined gap is sealed with a tape or the like, and a monomer of a lens material is injected into the gap (cavity) and cured, Manufactured by removing the glass mold. In the case of a single focus lens or a normal multifocal lens, the convex surface side is transferred to the final optical surface with a glass mold, and the concave surface side is transferred to a shape that meets a prescription within a certain range. The semi-finished lens is formed much thicker than the finished thickness. In the case of an inner surface progressive multifocal lens, the convex surface is transferred with a glass mold so that the final optical surface has a spherical or aspherical shape by the casting method, and the concave surface is transferred with a glass mold to a shape that fits a certain range of prescriptions. ing. A considerable number of semi-finished lenses must be prepared from combinations of outer shape, thickness, and the like.
[0037]
Next, before the polishing process, the computer for calculation selects an optimal semi-finished lens to be processed based on the design of the lens shape from the stocked semi-finished lenses and transmits the selected semi-finished lens to the host computer. Pick the corresponding semi-finished lens manually or automatically using an automated warehouse or the like.
[0038]
In the polishing process shown in FIG. 1, in the layout process, a positioning mark is set for setting the selected semi-finished lens on the block jig. This layout process is necessary for toric processing and prism processing of a multifocal lens whose vertical direction is determined, and can be omitted in the case of a single focus lens having no directionality.
[0039]
Next, in the blocking step, as shown in FIG. 1A, a block material 30 such as a low-melting-point metal is placed on the convex surface or concave surface of the semi-finished lens 11 on a block jig 20 for attachment to a numerically controlled machine tool. Glue through. At this time, it arrange | positions so that the positioning mark attached | subjected to the semifinished lens 11 may become a predetermined position with respect to the block jig | tool 20. FIG.
[0040]
Next, the shape creation process, which is a feature of the present invention, is performed. This shape creation step is a step of creating a lens surface shape based on the prescription of the spectacle lens by cutting and processing one side of the semi-finished lens. In some cases, the final optical surface may be obtained in the shape creation process. However, if there are fine irregularities on the surface, a mirror polishing process is performed to smooth the irregularities on the surface after the shape creation process.
[0041]
The shape creation process in the present invention includes an outer diameter machining process, an approximate machining surface rough machining process, a finishing machining process, and a chamfering process. The outer diameter machining step is a step for cutting an unnecessary outer peripheral portion by cutting and reducing it to a predetermined outer diameter, and is also a step for shortening the rough cutting step and the finishing step. The approximate machining surface rough cutting step is a rough cutting step in which an approximate surface shape that approximates a desired lens surface shape is quickly created, and a semi-finished lens having a considerable thickness is quickly cut to a predetermined thickness. In the finish cutting process, a desired lens surface shape is precisely created by machining from the approximate surface shape. The chamfering process is a process of chamfering the edge because the edge of the lens after the finishing process is sharp and dangerous, and is easy to chip. The outer diameter machining step is normally performed before the approximate machining surface rough cutting step, but may be performed before or after the finishing machining step. The outer diameter processing is not performed when the outer diameter of the semi-finished lens matches the prescription diameter. Further, chamfering may not be necessary. Furthermore, when the shape of the semi-finished lens is very close to the lens surface shape based on the prescription data of the spectacle lens, the lens surface shape based on the prescription data of the spectacle lens may be obtained only by direct finishing without rough cutting. .
[0042]
As an apparatus for performing the shape creation process, a dedicated cutting apparatus can be used for each process. Since the type of tool and the movement of the tool are different in each process, it is possible to perform cutting with the best cutting conditions using the best tool by using a dedicated cutting device. Good and efficient cutting can be performed.
[0043]
In the outer diameter machining step, a dedicated numerically controlled outer diameter machining cutting device (not shown) can be used. The block jig 20 is set on the chuck of this apparatus, and the outside diameter machining data is input to the numerically controlled outside diameter machining cutting apparatus. Alternatively, the outer diameter processing data is requested to the host computer via the communication line, the data is transmitted, and the data is stored in the internal storage device. The numerically controlled outer diameter machining cutting device controls the position of the cutting tool with respect to the Y axis direction and the workpiece radial direction (X axis) while rotating the workpiece on the Y axis based on the outer diameter machining data. A semi-finished lens 12 is manufactured by applying a cutting tool to the side surface of the finish lens 11 to cut the outer diameter and cutting it down to a predetermined diameter as shown in FIG.
[0044]
In the approximate machining surface rough cutting process, a dedicated numerically controlled machine tool can be used. As an example of a numerically controlled machine tool, FIG. 2 shows a schematic configuration of a numerically controlled cutting apparatus. This numerically controlled cutting apparatus 200 includes an X-axis positioning unit 202 and a Y-axis positioning unit 210 on a bed 201. The X-axis positioning means 202 is driven in the X-axis direction (perpendicular to the paper surface) by an X-axis drive motor and encoder 204. A work axis rotating means 205 is provided on the X-axis positioning means 202, and the work chuck 208 attached to the work rotating shaft 207 can be driven to rotate by a work rotation axis driving motor and encoder 206. The rotational position is determined. The Y-axis positioning means 210 is driven in a substantially horizontal Y-axis direction by a Y-axis drive motor and encoder 211. On the Y-axis positioning unit 210, a Z-axis positioning unit 212 and a blade rotating unit 213 are provided via a Z-axis column 214. The blade (circular cutter) 215 is rotationally driven by the blade rotating means 213 via the blade rotating shaft 216. The cutting tool 215 and the cutting tool rotating means 213 can be moved up and down in the Z-axis direction by the Z-axis driving motor and the encoder 217 of the Z-axis positioning means 212. The Z-axis positioning means 212 is provided mainly for the purpose of aligning the core height of the workpiece 12 and the circular cutter 215. The semi-finished lens (workpiece) 12 is held by the work chuck 208 via a block jig (not shown).
[0045]
In this numerically controlled cutting apparatus 200, the X-axis positioning unit 202 and the Y-axis positioning unit 210 are controlled in synchronization with the rotational position of the workpiece 12, and the relative positions of the workpiece 12 and the cutting tool 215 in the X-axis direction and the Y-axis direction are determined. Be controlled.
[0046]
The approximate machining surface rough machining data is directly input to the numerically controlled cutting apparatus 200 or transmitted via a host computer to store the data. The center coordinate of the circular cutter 215 is positioned in the normal direction set at the workpiece machining point using the three axes of the X-axis positioning unit 202, the Y-axis positioning unit 210, and the workpiece axis rotating unit 205. By continuously positioning the central coordinates of the circular cutter 215 corresponding to the machining point, the rough surface of the free curved surface, spherical surface or toric surface shape is created based on the rough machining data of the approximate machining surface described above. .
[0047]
In the approximate machining surface rough cutting step, as shown in FIG. 1C, a semi-finished lens 13 having a rough surface with a surface roughness Rmax of 100 μm or less can be obtained.
[0048]
In the finishing process, for example, a device similar to the numerically controlled cutting device 200 described above is used, and a precise cutting from the rough surface to the desired final lens surface shape is performed based on the finishing data using the finishing tool under the finishing cutting conditions. To cut.
[0049]
In the finish cutting step, as shown in FIG. 1D, a semi-finished lens 14 having a surface roughness Rmax of about 0.1 to 10 μm can be obtained.
[0050]
In the chamfering process, a dedicated numerically controlled chamfering cutting device (not shown) can be used. The block jig 20 is set on the chuck of this apparatus, and chamfering data is input to the chamfering cutting apparatus. Alternatively, the chamfering data is requested from the host computer via the communication line, the data is transmitted, and the data is stored in the internal storage device. The numerically controlled chamfer cutting apparatus chamfers the edge of the processed surface of the semi-finished lens 14 by applying a bite to the end edge of the semi-finished lens 14 while rotating the semi-finished lens 14 based on the chamfering data.
[0051]
In the chamfering process, as shown in FIG. 1E, a chamfered semi-finished lens 15 is obtained.
[0052]
After the shape creation process, a mirror polishing process for smoothing the surface irregularities is performed if necessary. In the above-described finishing, the surface roughness Rmax can be processed to about 0.1 to 10 μm, and the final optical surface having a surface roughness Rmax of about several tens of nm is finished in the mirror polishing process. In the case of polishing the concave surface of a single focus lens or the concave surface of a multifocal lens having a progressive surface on the convex surface, the mirror polishing step is a spherical surface or a toric surface, and therefore a polishing method using a conventional processing dish may be adopted. it can. When a complicated curved surface is polished like the polishing of the inner surface of the inner surface progressive multifocal lens, the conventional polishing method using a processing plate cannot be adopted as described above.
[0053]
For polishing a complicated curved surface such as such an inner surface progressive multifocal lens, it is preferable to use a copying polishing tool as shown in FIG. The copying polishing tool 40 is attached to the housing 42 so that a rubber sheet 41 having a hemispheric shape and flexibility forms a sealed space between the rubber sheet 41 and the housing 42, and pressure gas or liquid is press-fitted into the sealed space. The rubber sheet has a structure capable of applying pressure from the inside of the rubber sheet so as to keep the rubber sheet in a hemispherical form. A polishing cloth such as a non-woven fabric is attached to the surface of the rubber sheet 41, and polishing is performed by supplying a polishing liquid between the rubber sheet 41 and the work 16 while applying pressure to the work 16 by rotating and swinging the casing 42.
[0054]
In the copying polishing tool 40, since the rubber sheet 41 contacts the surface of the workpiece 16 with a uniform pressure, even if the surface of the workpiece 16 is a complicated curved surface, the rubber sheet 41 follows the shape of the surface of the workpiece 16 and is uniformly polished. can do. Therefore, it is particularly suitable for polishing a free curved surface such as the inner surface of an inner surface progressive multifocal lens.
[0055]
A numerically controlled polishing machine can be used for polishing a complicated curved surface. Based on the NC machining data calculated in advance from the design shape of the lens, relative positioning of the polisher head and the workpiece is performed, and any part of the surface of the polisher head is aligned with the normal direction at the machining point of the workpiece. Then, the polisher head is strongly pressed and polished from that direction. Thereby, it is possible to polish the final optical surface without breaking the curved surface shape created in the shape creation step.
[0056]
A finish lens in which both surfaces are the final optical surfaces is completed by the mirror polishing process. Thereafter, since the block jig 20 is not necessary, as shown in FIG. 1 (g), a deblocking process for removing the finish lens 17 from the block jig 20 is performed, and a cleaning process is performed to remove further adhered dirt. Finally, an inspection is performed and the polishing process is completed.
[0057]
Thereafter, the lens is completed through a dyeing process, a hard coat film forming process, an antireflection film forming process, and the like.
[0058]
By performing the shape creation process by machining using such numerical control, the conventional sanding process becomes unnecessary, and all kinds of curved surface shapes can be created. Therefore, the sanding process eliminates the need for a large number of processing dishes required for each lens surface shape, and also eliminates the need for auxiliary materials such as abrasives and polishing pads, thereby reducing production costs.
[0059]
In the above description, a dedicated polishing apparatus is used for each polishing process. However, in the shape creation process according to the present invention, outer diameter machining, approximate machining surface rough machining, finish machining and chamfering that constitute the shape creation process are performed. This can be done using a single numerically controlled machine tool.
[0060]
FIG. 3 shows a schematic configuration of a numerically controlled turning apparatus as an example of the numerically controlled machine tool. This numerically controlled turning apparatus 300 includes an X-axis positioning unit 310 and a Y-axis positioning unit 320 on a bed 301. The X-axis positioning unit 310 is driven in the substantially horizontal X-axis direction by the X-axis drive motor and encoder 311. The position in the X-axis direction is determined by the encoder 311. A workpiece axis rotating means 312 is fixed on the X axis positioning means 310. A work chuck 313 is attached to the work shaft rotating means 312 and is driven to rotate by a work rotation shaft driving motor and an encoder 314. The rotation position of the work chuck 313 is determined by the encoder 314. A semi-finished lens (work) 11 is attached to the work chuck 313 via a block jig. The Y-axis positioning unit 320 is driven by a Y-axis driving motor and encoder 321 in a substantially horizontal Y-axis direction orthogonal to the X-axis positioning unit 310. The position in the Y-axis direction is determined by the encoder 321. On the Y-axis positioning means 320, two first tool rests 322 and a second tool rest 323 are fixed, and a rough cutting tool (cutting tool) 324 is fixed to the first tool rest 322, and a second tool rest. A finishing bit 325 is fixed to the H.323. The rough cutting tool 324 is made of, for example, cemented carbide, and the finishing tool 325 is made of, for example, single crystal diamond.
[0061]
The control method is to use the three axes of the X-axis positioning unit 310, the Y-axis positioning unit 320, and the workpiece axis rotating unit 312 to set the center coordinates of the tip of the cutting tool 324 or the cutting tool 325 in the normal direction set at the machining point of the workpiece 11. Position it. The shape creation based on the lens design shape is performed by continuously positioning the center coordinates of the tip of the cutting tool corresponding to the processing point. At this time, the work 11 is rotated by the work shaft rotating means 312 at a rotation speed between 100 and 3000 rpm depending on the shape, roughness, and finishing of the work. The rotational position is determined by the encoder 314, and the Y-axis positioning unit 320 and the X-axis positioning unit 310 are positioned in synchronization with the rotation of the workpiece 11. That is, while rotating the workpiece 11, the relative positions of the workpieces 11, which are the rotation axes of the workpiece 11, in the Y-axis direction, and the workpieces 11, and the relative positions of the workpieces 11, 324, 325, and the workpiece 11 are determined. This is synchronized with the rotation of the workpiece 11.
[0062]
This numerically controlled turning apparatus 300 is configured to perform cutting by switching between a roughing cutting tool 324 and a finishing cutting tool 325, and using the roughing cutting tool 324 to perform outer diameter processing and approximate machining surface roughing processing, Finishing cutting and chamfering are performed using a finishing bit 325.
[0063]
The numerically controlled turning apparatus 300 includes outer diameter machining data, approximate surface machining rough machining data, finishing machining data, and chamfering data calculated by a computer for calculation based on prescription data of spectacle lenses input from an input device. The numerical control machining data is transmitted via a host computer and stored in an internal storage device.
[0064]
A semi-finished lens 11 fixed to a block jig 20 as shown in FIG. 1A is fixed to a work chuck 313, and semi-finished based on outer diameter processing data given to the semi-finished lens 11. The lens 11 is cut with a roughing cutting tool 324 until the outer diameter of the lens 11 reaches a predetermined diameter. Subsequently, rough cutting with the surface roughness Rmax of 100 μm or less with the above-mentioned free-form surface, toric surface or spherical surface shape approximated to a desired lens surface shape based on rough surface cutting data on the rough surface using a roughing cutting tool 324. Is cut into a surface. Subsequently, the remaining 0.1 to 5.0 mm is cut based on the finish cutting data using the finishing bit 325 and based on the prescription data of the spectacle lens whose surface roughness Rmax is about 0.1 to 10 μm. The lens surface shape is processed. Subsequently, chamfering is performed based on the chamfering data using the finishing bit 325.
[0065]
Shape creation in which a series of shape creation processes are continuously performed without removing the workpiece from the work chuck using one numerically controlled machine tool 300 having two types of tools such as a roughing tool 324 and a finishing tool 325. The method has the following advantages as compared with the above-described method using different apparatuses for each process.
[0066]
Since the processes and devices are integrated into one machine and one process, a processing machine is not required for each process, and it is not necessary to place an operator for each machine. As a result, not only can the production cost be reduced by reducing labor costs, but also the yield can be improved and the yield can be improved and the quality can be stabilized and improved by preventing a decrease in yield and quality variations due to human error. Furthermore, it is possible to eliminate the need for inspection performed for each process.
[0067]
In the numerically controlled turning apparatus 300 described above, two types of cutting tools are used. However, three or more types of cutting tools are provided, and each cutting can be performed with a cutting tool dedicated to each processing. Moreover, it can be used as a dedicated device for each of approximate machining surface roughing and finishing using one type of tool. Furthermore, the workpiece is moved in the X-axis direction and the tool and the tool are moved relative to each other in the Y-axis direction. However, the work is placed at a fixed position, and the tool is placed in the X-axis direction and the Y-axis. You may make it move to an axial direction.
[0068]
Next, a procedure for creating numerical control machining data in the present invention will be described. FIG. 4 is a flowchart showing a procedure of calculation of numerical control machining data when creating a shape with a numerically controlled machine tool.
[0069]
First, in step 401, prescription data for a spectacle lens desired by a customer is acquired. In general, this prescription data includes S (spherical) power, C (astigmatism) power, astigmatic axis, addition power, prism, eccentricity, lens thickness, lens diameter, color and the like in the case of a progressive multifocal lens. . In the case of a single focus lens, S power, C power, astigmatism axis, prism, eccentricity, lens thickness, lens diameter, color, and the like are included. These prescription data are transmitted directly from a terminal provided in the spectacle retailer directly to the host computer of the manufacturing department of the lens manufacturer. Alternatively, the relay base receives prescription data from a retail store by a transmission means such as telephone and facsimile, and is transmitted online from the relay base. Furthermore, it is also possible to input directly to the host computer using input means.
[0070]
Next, in step 402, based on the prescription data input to the host computer, the prescription data is processed into production data for the production line by the calculation computer, and based on this production data, that is, based on the customer's prescription. The combination of curved surfaces is calculated, and the lens shape is designed as numerical data for each customer prescription.
[0071]
Next, in step 403, it is determined whether or not a prism is included in the prescription data of the spectacle lens. A prism is a vector, has a direction and a size, and is usually represented by a base direction (0 to 359 °) and a length. If a prism is included, in step 404, the prism amount data is added to the numerical data of the lens shape according to the prism amount, and correction is performed. Specifically, numerical data representing the processed surface (designed surface) is inclined by an arbitrary amount in the arbitrary direction by the prism amount, and numerical data of the lens shape is obtained based on the newly obtained processed surface.
[0072]
FIG. 5A conceptually shows a case where a prism is added by a conventional polishing method, and FIG. 5B conceptually shows a case where a prism is added by the polishing method of the present invention.
[0073]
The lens substrate 11 is bonded and fixed to the block jig 20 via a low melting point metal 30. The low-melting-point metal 30 is formed by being injected and solidified in a liquid state in a gap portion of a hollow jig (not shown) interposed between the adhesion surface of the lens substrate 11 and the block jig 20.
[0074]
When a prism is added by a conventional polishing method, it is necessary to incline the lens substrate 11 itself, so that a hollow jig corresponding to the amount of prism is necessary. In a multifocal lens having a progressive surface on the normal outer surface side, it is necessary to closely contact the convex surface side and the hollow jig, so a base jig of the lens base material, a hollow jig corresponding to the addition, is necessary, A huge number of hollow jigs are required. In addition, there was a large variation in alignment with the hollow jig manually, which was a cause of defects. After polishing, as shown in FIG. 5A, the optical center (fitting point, that is, the center of the pupil when framed in the frame) of the reference surface S of the block jig 20 and the processed surface. The tangent line L1 at the point) is parallel.
[0075]
On the other hand, in the manufacturing method of the present invention, as shown in FIG. 5 (b), the machining surface is in an arbitrary direction in an arbitrary direction with an intersection A between the machining rotation axis MC and the machining surface as a fulcrum (a point that defines the inclination). All you need to do is calculate the slope. Thereby, it is possible to create a machining surface in which the tangent line L2 at the optical center of the machining surface is inclined by an angle corresponding to a predetermined prism amount with respect to the reference surface S of the block jig 20. As a result, the prism can be added only by changing the numerical data, so that an enormous number of hollow jigs are not required and variations due to manual work do not occur.
[0076]
Returning to FIG. 4, next, in step 405, it is determined whether or not the spectacle lens prescription data includes eccentric processing. The eccentric processing is performed for the purpose of reducing the outer diameter of the lens. The amount of eccentricity is a vector and has a direction and a magnitude. Usually, it is represented by a base direction (0 to 359 °) and a prism amount. If eccentric processing is included, in the next step 406, the eccentricity data is added to the numerical data of the lens shape to perform correction. Specifically, numerical data representing the machining surface (design surface) is offset by an arbitrary amount in an arbitrary direction from the geometric center (a point located at the center when indexed from the lens outer diameter) by an eccentric amount, Based on the newly obtained processed surface, numerical data of the lens shape is obtained.
[0077]
FIG. 6A conceptually shows the case where the eccentric amount is added by the conventional polishing method, and FIG. 6B conceptually shows the case where the eccentric amount is added by the polishing method of the present invention.
[0078]
In the case of adding an eccentric amount by a conventional polishing method, it is necessary to fix the lens base 19a itself by decentering the optical center OC by a predetermined amount with respect to the processing rotation axis MC when blocking. Therefore, since it is necessary to incline and fix the lens base material 19a to the block jig 20, a hollow jig corresponding to the amount of eccentricity is required.
[0079]
After the polishing, as shown in FIG. 6A, the processing rotation axis MC of the block jig 20 and the geometric center of the processing surface coincide. The optical center OC and the processing rotation axis MC are separated by an eccentric amount. A huge number of hollow jigs are required as in the prism. In addition, there was a large variation in alignment with the hollow jig manually, which was a cause of defects.
[0080]
On the other hand, in the manufacturing method of the present invention, as shown in FIG. 6B, it is only necessary to perform a calculation for decentering the machining surface from the geometric center MC in an arbitrary amount. As a result, it is possible to create a processing surface in which the processing rotation axis MC of the block jig 20 and the optical center OC of the processing surface of the processed lens 19b are decentered. As a result, since the amount of eccentricity can be added only by changing the numerical data, an enormous number of hollow jigs are not required, and variations due to manual work do not occur.
[0081]
Next, in step 407 of FIG. 4, the processing conditions are selected. If the machining conditions of the numerically controlled machine tool are not appropriate, chipping (fine omission) occurs on the workpiece surface due to the machining resistance during shape creation machining. Since this chipping is difficult to remove in a later process, it is necessary to set processing conditions so as not to cause chipping. In particular, an extremely high refractive index material having a refractive index exceeding 1.74 or a brittle material such as a CR-39 lens tends to cause chipping.
[0082]
The machining conditions of the numerically controlled machine tool are the workpiece rotation speed, the feed pitch that is the amount of movement of the blade for each rotation of the workpiece, the cutting depth that is the depth at which the workpiece is difficult to be inserted, the peripheral speed, and the like. The computer for calculation is combined with machining conditions according to the shape and lens material of the lens based on spectacle lens prescription data in rough machining, finish machining, outer diameter machining, chamfering machining, etc. A plurality of processing patterns are stored. The calculation computer calculates the final lens shape numerical data by adding the prism and the eccentricity to the lens shape numerical data based on the spectacle lens prescription, and based on the final lens shape numerical data and the lens material. Select the optimum machining pattern from multiple machining patterns. Alternatively, the operator may select a processing pattern and input it to the computer for calculation.
[0083]
As specific processing conditions, in the case of a numerically controlled machine tool that controls the positions of the X-axis and Y-axis of the cutting tool in synchronization with the above-described workpiece rotation, the workpiece rotation speed is 100 to 3000 rpm for rough machining, and finish machining. 100 to 3000 rpm, the feed pitch is 0.005 to 1.0 mm / rev for rough machining, 0.005 to 0.2 mm / rev for finishing, and the cutting amount is 0.1 to 10.00 mm / rev for rough machining. In the pass and finish processing, the range is 0.05 to 3.0 mm / pass. In the case of a numerically controlled machine tool that performs two-axis synchronous processing of X and Y, such as outer diameter machining and chamfering, the workpiece rotation speed is 100 to 20000 rpm for rough machining, 100 to 20000 rpm for finishing, and the feed pitch is In the roughing process, 0.005-1.0 mm / rev, in the finishing process, 0.005-0.2 mm / rev, the cutting depth is 0.1-10.00 mm / pass in the roughing process, and 0.05 in the finishing process. It is the range of -3.0 mm / pass.
[0084]
The setting of the feed pitch is the most important among the machining conditions, and it is preferable to change the feed pitch according to the relative position between the workpiece and the cutting tool. For example, it is preferable to reduce the feed pitch in the outer peripheral portion where the distance from the center of rotation of the workpiece is large, that is, in the portion where the relative speed between the cutting tool and the workpiece is high, or in the portion where the surface shape changes greatly. On the other hand, when the feed pitch is increased, the productivity is increased. Therefore, when chipping that can be removed by finishing is generated, the feed pitch is increased as much as possible.
[0085]
7 and 8 show examples of feed pitch setting patterns. In each pattern graph, the horizontal axis represents the distance from the rotation center of the workpiece, and the vertical axis represents the feed pitch. The numerical values on the horizontal axis are examples. Since the cutting tool normally moves from the outer peripheral part to the inner peripheral part during cutting, each pattern will be described from the viewpoint of the movement of the cutting tool. FIG. 7 (1) shows a pattern in which the feed pitch is constant regardless of the distance from the center of the workpiece. In this case, the feed pitch is appropriately selected depending on the material and shape of the workpiece. (2) in FIG. 7 shows a pattern (solid line) and an inner circumference in which P1 is maintained at a constant feed pitch Po at the outer peripheral portion and the central portion of the workpiece, and P1 is maintained after the feed pitch is reduced to P1 when entering the inner peripheral portion. This is a pattern (broken line) that gradually decreases the feed pitch from P0 to P1. (3) in FIG. 7 is a pattern in which P0 is maintained by increasing the feed pitch to P0 at the entrance of the inner periphery at a constant feed pitch of P1 at the outer periphery. (4) in FIG. 7 shows a pattern (solid line) in which the feed pitch P0 is constant at the outer peripheral portion and the inner peripheral portion and the feed pitch is reduced to P1 at the central portion, and a constant feed pitch P1 at the outer peripheral portion and the inner peripheral portion. The pattern (broken line) increases the feed pitch to P0 at the center. In this case, the feed pitch between the outer peripheral portion and the inner peripheral portion may be different.
[0086]
(5) in FIG. 8 is a pattern in which the feed pitch is gradually changed linearly from the outer peripheral part to the inner peripheral part. The pattern (broken line) in which the feed pitch increases from the outer peripheral part to the inner peripheral part and the inner peripheral part to the inner peripheral part. It is a pattern (solid line) in which the feed pitch decreases over the part. (6) in FIG. 8 shows a pattern (solid line) in which the feed pitch is sharply reduced at the outer peripheral portion, and the feed pitch is gradually reduced at the central portion and the inner peripheral portion, and the feed pitch is gradually increased from the outer peripheral portion to the central portion. It is a pattern (broken line) that increases and the feed pitch suddenly increases in the inner periphery. (7) in FIG. 8 shows a continuous pattern (solid line) in which the feed pitch is the largest in the central portion and the feed pitch is small in the inner and outer peripheral portions and the feed pitch is the smallest in the central portion and the feed is sent in the outer and inner peripheral portions. It is a continuous pattern (broken line) in which the pitch increases. (8) in FIG. 8 shows a pattern (broken line) in which the feed pitch decreases stepwise from the outer peripheral portion to the inner peripheral portion and a pattern (solid line) in which the feed pitch increases stepwise from the outer peripheral portion to the inner peripheral portion.
[0087]
An appropriate feed pitch pattern is selected from these patterns according to the final lens shape, lens material, and the like. For example, in the rough machining of the approximate machining surface, even if chipping occurs, it can be removed during the finishing machining. Therefore, P1 = 0.05 to 0.20 mm / rev in the pattern of the broken line in FIG. P0 = 0.10 to 0.40 mm / rev can be employed.
[0088]
Further, in the finish cutting, the majority employs the pattern shown in FIG. 7 (1). For example, the range is P0 = 0.01 to 0.10 mm / rev. When the astigmatism is 2.00 D or more regardless of the refractive index of the lens, chipping is likely to occur, so the pattern shown in FIG. In this case, for example, P0 = 0.03 to 0.10 mm / rev and P1 = 0.01 to 0.07 mm / rev, and the range of the feed pitch of P1 is 5 to 15 mm from the outermost periphery.
[0089]
For brittle materials such as an ultra-high refractive index lens with a refractive index of 1.74 and CR-39, the pattern (1) is adopted regardless of the shape, and P0 = 0.05 mm / rev or less is desirable. When the astigmatism is 2.00 D or more, the outer peripheral portion has a lower pitch (3) in FIG. 7, the broken line in (5) in FIG. 8, the broken line in (6) in FIG. 8, and the (8) in FIG. The solid line pattern is adopted.
[0090]
Further, since the cutting tool is difficult to occur in the spherical surface and the asymmetric aspherical surface because the cutting tool advances only in one direction, P0 = 0.03 to 0.10 mm / rev is adopted in the pattern of FIG. In this case, the broken line pattern in FIG. 8 (6) that can achieve both high productivity and cutting quality may be used, and values of P0 = 0.07-0.20 mm / rev and P1 = 0.02-0.07 mm / rev are used. Use and approximate with quadratic function.
[0091]
For example, when the countermeasure for chipping is insufficient even if the feed pitch at the outer peripheral portion is lower than that at the inner peripheral portion as in the case of the pattern of FIG. 7 (3), a normal rotational speed, for example, 300 to 1000 rpm is set to 20 to 40. It is also effective to reduce it by about%.
[0092]
7 (2) and the broken line pattern in FIG. 7 (4) are easily peeled off at the center in the case of a plastic lens, the feed pitch is lowered at the center (P0 = 0.03-0.10 mm / rev, P1 = 0.01-0.03 mm / rev). In the broken line pattern of FIG. 7 (4), P1 may be different between the outer peripheral portion and the inner peripheral portion. For example, P1 = 0.03 mm / rev at the outer periphery and P1 = 0.01 mm / rev at the inner periphery.
[0093]
In addition, it is possible to control the peripheral speed to be constant by changing the work rotation speed in accordance with the position of the cutting tool in the work radial direction. Such a control method can effectively suppress the occurrence of chipping at the outer periphery.
[0094]
Finally, in step 408, the computer for calculation creates numerical control machining data used in the numerically controlled machine tool based on the obtained numerical data of the final lens shape and the machining pattern. The obtained numerical control machining data is transmitted to the host computer and stored. The shape creation process described above is performed based on the numerical control machining data.
[0095]
In the description of the creation of the numerical control machining data, the correction of the prism and the correction for decentration are performed in separate steps. However, both the correction is performed because the prism and the decentration are vectors. May be performed simultaneously.
[0096]
According to the embodiment of the eyeglass lens manufacturing method of the present invention, the shape creation process by machining is an outer diameter machining process, approximate machining surface rough machining process, finishing machining process, and chamfering process, each of which has different types and movements of tools. By dividing, it becomes possible to perform machining with optimum cutting conditions using the optimum cutting tool for each machining, and it is possible to create a shape with high accuracy and speed.
[0097]
In addition, at least approximate roughing and finishing processes are machined using a numerically controlled machine tool, so it is possible to create any lens curved surface shape, including the inner surface of an inner surface progressive multifocal lens with a complex curved surface. became.
[0098]
Furthermore, by using a numerically controlled machine tool that can selectively use at least two types of tools, that is, a finishing tool and a roughing tool, all processes in the shape creation process can be performed continuously with a single numerically controlled machine tool. This makes it possible to produce lenses with high quality and stable quality.
[0099]
Further, in the spectacle lens manufacturing method of the present invention, since the prism and eccentric processing can be dealt with only by computation without changing the jig, a spectacle lens having excellent processing accuracy can be manufactured with high productivity.
[0100]
In addition, the processing pattern can be changed according to the lens surface shape and lens material based on the spectacle lens prescription to increase the cutting speed while suppressing chipping. Property can be improved.
[0101]
【The invention's effect】
As described above, according to the spectacle lens manufacturing method of the present invention, it is possible to create a shape of a lens surface having a complicated curved surface with high productivity.
[Brief description of the drawings]
FIG. 1 is a flowchart showing steps of a method for manufacturing a spectacle lens according to the present invention, wherein (a) to (g) are schematic views showing processing in each step.
FIG. 2 is a side view showing a schematic configuration of a numerically controlled cutting apparatus used in the method for manufacturing a spectacle lens of the present invention.
FIG. 3 is a top view showing a schematic configuration of a numerically controlled turning apparatus used in the method for manufacturing a spectacle lens of the present invention.
FIG. 4 is a flowchart showing an example of a procedure for creating numerical control machining data.
FIGS. 5A and 5B are schematic side views showing the arrangement of a workpiece with respect to a block jig when a prism is added in a shape creation process, where FIG. 5A shows a conventional method and FIG. 5B shows a method of the present invention.
FIGS. 6A and 6B are a schematic side view and a top view showing an arrangement of a workpiece with respect to a block jig when adding eccentricity in a shape creation process, where FIG. 6A is a conventional method, and FIG. 6B is a method of the present invention. Show.
FIGS. 7A to 7D are graphs each showing a feed pitch pattern.
FIGS. 8A to 8D are graphs each showing a feed pitch pattern; FIGS.
[Explanation of symbols]
11 Semi-finished lens
12 Semi-finished lens after outer diameter processing
13 Semi-finished lens after rough machining of approximate surface
14 Semi-finished lens after finishing
15 Semi-finished lens after chamfering
16 Semi-finished lens during mirror finishing
17 Finish lens
20 Block jig
30 block material
40 Copy polishing tool
41 Rubber sheet
42 Case
200 Numerically controlled cutting equipment
201 beds
202 X-axis positioning means
204 X-axis drive motor and encoder
205 Work axis rotation means
206 Workpiece rotary shaft drive motor and encoder
207 Workpiece rotation axis
208 Work chuck
210 Y-axis positioning means
211 Y-axis drive motor and encoder
212 Z-axis positioning means
213 Cutting tool rotating means
214 Z-axis column
215 circular cutter
216 Blade rotation axis
217 Z-axis drive motor and encoder
300 Numerically controlled turning device
301 beds
310 X-axis positioning means
311 X-axis drive motor and encoder
312 Workpiece axis rotation means
313 Work chuck
314 Work Rotating Shaft Drive Motor and Encoder
320 Y-axis positioning means
321 Y-axis drive motor and encoder
322 First tool post
323 2nd tool post
324 Roughing tool
325 Finishing tool

Claims (2)

A spectacle lens manufacturing method comprising a shape creation step of creating a lens surface shape based on a prescription of a spectacle lens on the spectacle lens base material by processing either one or both surfaces of the spectacle lens base material,
Approximate machining surface roughening step in which the shape creation step creates an approximate surface shape that approximates the lens surface shape based on the prescription of the spectacle lens on the spectacle lens base material by machining by numerical control based on numerical control processing data And a finish cutting step of creating a lens surface shape based on the prescription of the spectacle lens from the approximate surface shape by a machining process by numerical control based on numerical control processing data,
The cutting process by the numerical control is performed by rotating the spectacle lens base material while rotating the spectacle lens base material in the direction of the rotation axis of the spectacle lens base material and the relative position of the spectacle lens base material and in the direction orthogonal to the rotation axis. It is performed by synchronizing the relative position of the blade and the spectacle lens substrate with the rotation of the spectacle lens substrate,
At least in the finish cutting step, the eyeglass lens is machined while changing the feed pitch of the blade synchronized with the rotation according to the relative position of the eyeglass lens base material and the blade changing according to the lens surface shape In the manufacturing method of
The method for manufacturing a spectacle lens, wherein a feed pitch of the cutting tool at the outer peripheral portion and / or the central portion of the spectacle lens base material in the finishing cutting step is smaller than other portions. In the finishing process,
When the prescription of the spectacle lens substrate is astigmatism 2.00D or more, the feed pitch of the cutting tool in the central portion of the spectacle lens substrate is larger than the feed pitch in other portions of the spectacle lens substrate, The method for manufacturing a spectacle lens according to claim 1.

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