JPH11198014A - Manufacture of plastic lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cutting precision and polishing precision without depending on a shape of a lens by fixing an overall convex surface of a workpiece on a block jig by using a thermoplastic resin. SOLUTION: A workpiece 30 is stopped at a position where a side surface of the workpiece 30 is roughly buried by pouring a thermoplastics resin 50 in a melted or half-melted state in to a form 20 of a fixing jig 1, lowering the workpiece 30 and making it intrude into the thermoplastic resin 50 after setting the fixing jig 1 in a prescribed attitude by arranging it at a prescribed position. The workpiece 3, is fixed in a state where it is buried in a block material at prescribed inclination and in an astigmatic axial direction relative to a block jig 10. A lens 31 the thickness of which is extremely reduced is manufactured by cutting all of the side surface of the workpiece 30 from the original workpiece 30 before cutting and proceeding cutting until the state where a diameter is reduced smaller than the original workpiece 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a plastic lens for forming a lens surface by cutting a resin-made work.

[0002]

2. Description of the Related Art In recent years, light plastic lenses have become the mainstream for spectacle lenses, and this is particularly remarkable for multifocal lenses for bifocals. A multifocal lens is a lens in which one lens has different powers.For example, the upper side of the lens is a distance portion for seeing far away, and the lower side is a near portion for seeing close up. Progressive multifocal lenses in which the power of the lens continuously changes from a distance portion to a near portion, and further to an intermediate portion for viewing an intermediate distance between them are becoming common.

In such a multifocal lens, the lens surface is cut and polished in accordance with necessary conditions such as the power and the astigmatic angle according to the individual prescription of the user. In this case, a semi-finished lens in which a curved surface corresponding to the power is formed on the convex surface side of the lens is manufactured, and adjustment of the astigmatic angle, prism angle, and the thickness of the entire lens is performed in accordance with the prescription. There is a polishing manufacturing system for cutting and polishing the inner concave side of a finish lens to finish it into a finished lens. For a multifocal lens, a lens horizontal line serving as a reference in the horizontal and vertical directions when worn is determined. Since the amount of prism and the axis of astigmatism vary from person to person, each lens is formed on the concave side according to the prescription.

A conventional method of manufacturing a plastic lens in such a semi-finish system is shown in FIGS.
0 will be described. The manufacturing process consists of a blocking step of fixing a blank (working work) to a blocking jig, a cutting step of cutting the work piece fixed to the blocking jig with a cutting wheel, and a block jig of the processed work piece after the cutting step. And a deblocking step of removing the work from the block jig.

FIG. 5 shows a fixing jig used for fixing a work to be a plastic lens. The fixing jig 100 includes a block jig 110 for setting in a cutting device or a polishing device and a prism ring 12.
It is composed of 0 combinations. Block jig 110
Is a block material injection port 111 for injecting a low melting point metal.
And is fixed in a fixed direction when set in a cutting device or a polishing device.
The prism ring 120 has a box shape composed of a circular bottom plate and a peripheral wall surrounding the bottom plate. The block jig 110 is fitted to a hole formed in the bottom plate and used in combination. The upper edge of the peripheral wall of the prism ring 120 is
It is formed diagonally to set the prism amount on the completed lens according to the prescription of the user, and the inclination θ from the horizontal direction
Are formed. Since the amount of prism differs for each user, a prism ring having a different inclination θ for each amount of prism is prepared because there is no inclination.

[0006] As shown in Fig. 5, the block jig 110 and the prism ring 120 are fitted together. Then, as shown in Fig. 6, the block jig 110 is used to determine the axis of astigmatism.
The prism ring is rotated at a predetermined angle according to the prescription while keeping the fixed. Then, the convex side of the work 130 is placed on the prism ring 120 so that the reference line 121 of the prism ring 120 and the work reference line 131 are aligned. Next, the block material injection port 11 of the block jig 110
The low-melting metal 140 melted from 1 is poured into a cavity formed by the work 130, the prism ring 120 and the block jig 110, and the low-melting metal 140 is solidified. Thereafter, the prism ring 120 is removed, and as shown in FIG. 7, the processing work 130 is moved through the block jig 110 via the block material 141 made of the low melting point metal 140.
Is fixed so as to have a predetermined prism amount and a predetermined astigmatic axis.

In the cutting step, as shown in FIG. 8, the block jig 110 is fixed to a cutting machine (not shown) and the concave side of the work 130 is cut by a rotating cutting wheel 150 so as to have a predetermined lens surface. . In this cutting step, as shown in FIG. 9, in order to reduce the thickness of the lens, cutting is performed until the diameter becomes smaller than the original work 130 shown by the broken line, and the special lens 131 of the knife etch having no edge thickness is used. Sometimes it is processed.

In the polishing step, as shown in FIG. 10, a polishing surface is polished by rubbing a polishing cloth 151 stuck on a polishing jig 150 with a cutting surface of a work 132 to perform mirror finishing.

After the polishing step is completed, the work 132
Is performed to separate the low-melting-point metal 140 from the completed work, thereby obtaining a lens having a completed shape.

[0010]

However, the above-mentioned conventional method of manufacturing a plastic lens has the following problems.

First, in the blocking step, a large number of prism rings 120 must be prepared, and there is a problem that the step cannot be automated. Prism ring 120
Determines the setting direction for setting the astigmatic axis of the work 130, sets the amount of prism required for the completed lens, and functions as a mold for the low melting point metal used for the block material. Therefore, it is necessary to prepare an enormous number of prism rings 120 depending on the combination of the amount of prism, the type of lens diameter, the curved surface shape of the convex side of the work, and the type of refractive index of the lens.

Using a large number of prism rings as described above,
In addition, since the setting direction of the work piece is adjusted, the blocking step is a manual operation, and there is a problem that the production efficiency is low.

Next, in the cutting step, there is a problem that the cutting accuracy is low. The blocking material 141 is a low-melting metal, and the cutting foil 150 is damaged when it hits the cutting foil 150. Therefore, the diameter of the blocking material 140 needs to be smaller than the convex surface of the work 130. Therefore, as shown in FIG. 8, the outer peripheral portion of the work 130 that is not supported by the blocking material 140 is
At the time of cutting at 50, a phenomenon occurs in which the cutting wheel 150 is pressed by the cut amount of the cutting wheel 150 and bends as indicated by an arrow. As a result, the cutting accuracy of the outer peripheral portion of the work 130 is reduced,
There is a problem that the curvature accuracy deteriorates. The effect of this problem increases as the thickness of the outer peripheral portion of the work 130 decreases. In addition, since the bending of the outer peripheral portion of the processing work 130 also has an adverse effect on the processing accuracy of the central portion and is not cut into a shape as designed, at present, a correction derived from experience is performed, and a shape as designed is obtained. Is being done.

Further, in the case of processing into a knife etch as shown in FIG. 9, since the thinned knife etch portion is in a floating state, the processing accuracy is further deteriorated. They are changed to achieve the desired quality and accuracy, but the cutting conditions are changed according to the shape, which is a complicated operation. Also, when processing into a knife etch, the block material must be formed using a prism ring with a small diameter according to the amount to be cut in order to make it smaller than the diameter of the original work piece. Has become an element of many types.

In the polishing step, as shown in FIG. 10, the outer peripheral portion of the workpiece is pressed by the pressure of rubbing with the polishing jig and deforms in the direction of the arrow, so that residual polishing and sagging at the outer peripheral portion easily occur. There is a problem that appearance quality deteriorates.
Also, when processed into a knife etch, the polishing cloth or polishing jig may be damaged by the etch, and the processed work is likely to be chipped or cracked at the knife-etched portion. There is a problem that the quality is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a plastic lens which can be automated by eliminating a large number of prism rings required in a blocking step, and which can obtain the processing accuracy and quality required in a cutting step and a polishing step. It is an object of the present invention to provide a method for producing the same.

[0017]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that using a thermoplastic resin as a block material in place of a conventional low melting point metal, the entire convex surface of the work piece is used. It has been found that the above-mentioned problems can be solved by fixing to the block jig.

That is, when a thermoplastic resin is used as a block material, the thermoplastic resin can be cut together with the work to be processed. Therefore, unlike a low melting point metal, it is not necessary to make the diameter of the work to be smaller than the diameter of the work. Can be fixed to a block jig with a thermoplastic resin, and the work can be fixed to the block jig in a state where the work is half-buried in the thermoplastic resin.

For fixing the work to the block jig, for example, a box-shaped fixing jig is formed by combining a frame mold and a block jig, and a molten thermoplastic resin is poured into the fixing jig. This can be facilitated by arranging the work to be processed, solidifying the thermoplastic resin, and then removing the frame from the block jig.

For this reason, the inclination of the processed work with respect to the block jig for giving the prism amount can be easily achieved by, for example, solidifying the thermoplastic resin while the fixing jig is inclined. Further, the angle of astigmatism can be easily given by rotating the work or the block jig.
Therefore, it is not necessary to use a prism ring, which is conventionally required in many cases, and these operations can be automated by an automatic device by numerical control.

In the cutting step and the polishing step, since the entire convex surface of the work is fixed, the outer peripheral portion of the work is not bent by the pressing force at the time of cutting or polishing. Therefore, cutting and polishing can be performed with high accuracy. In addition, in knife-etch processing, the knife-etch portion is always fixed with a block material, so it can be cut and polished with the same precision as a lens with a regular edge, and is resistant to chips and cracks, and is made of high-quality plastic. Finding that a lens can be manufactured,
The present invention has been made.

Accordingly, the present invention provides a blocking step of fixing one entire surface of a resin-made work to be a plastic lens to a block jig via a thermoplastic resin, and disposing the block jig in a cutting device. And a cutting step of cutting the other surface of the processed work to form a lens surface.

[0023]

Embodiments of the present invention will be specifically described below with reference to the drawings. As described above, the plastic lens manufacturing method of the present invention includes a blocking step of fixing one entire surface of a resin-made work to be a plastic lens to a block jig via a thermoplastic resin, and the block jig. Is placed on the cutting device,
Cutting the other surface of the work to form a lens surface.

The work to be processed may be a so-called semi-finished blank in which a curved surface is formed in advance as a multifocal lens of a thermosetting synthetic resin and the concave surface is not particularly processed.

FIG. 1 shows an embodiment of a fixing jig for fixing a work to be used in a blocking step. The fixing jig 1 is configured by a combination of a block jig 10 and a frame mold 20. The block jig 10 has a fitting portion 11 for fitting and fixing in a predetermined direction to a cutting machine or a polishing machine.
And a disk-shaped receiving plate 12 slightly larger than the diameter of the work to be processed. Further, the frame mold 20 is a flat bottomed cylindrical shape, the inner diameter is substantially equal to the outer diameter of the receiving plate 12 of the block jig 10,
The bottom plate 21 has an opening through which the fitting portion 11 of the block jig 10 passes. As shown in FIG. 1, the block jig 10 and the frame die 20 pass through the fitting portion 11 of the block jig 10 through the opening of the frame die 20, and the receiving plate 12 of the block jig 10 Used to assemble to fit in the bottom of.

FIG. 2 shows a method of blocking the work 30 using the fixing jig 1 shown in FIG. In the blocking step, a positioning control device (not shown) is used. This positioning control device includes a vertical positioning function for moving the work suction jig 40 up and down to stop at a predetermined position, a rotation positioning function for rotating the work suction jig 40 in a predetermined direction and stopping, and a fixing jig. 1, a tilt positioning function for tilting a holder (not shown) at a predetermined angle, a rotation positioning function for rotating the holder in a predetermined direction and stopping, and a horizontal function for moving the holder in the XY directions by a predetermined amount. It has a direction positioning function, and can perform these controls by numerical control so that the work suction jig 40 and the holder can be arranged at predetermined positions.

Then, the work 30 is set on the work suction jig 40, and the fixing jig 1 is set on the holder (not shown). By driving the positioning control device,
In order to give a prism amount set in advance according to a prescription, the fixing jig 1 is given an inclination θ at a predetermined angle from the horizontal. Further, in order to determine the axis of astigmatism of the work 30, the suction jig 40, that is, the work 30 and the fixing jig 1 are relatively rotated at a predetermined angle and arranged at a predetermined angle. Further, in order to correct the displacement between the center axis of the block jig 10 and the center of the work 30 due to the inclination of the fixing jig 1, the fixing jig 1 is moved in a horizontal direction by a predetermined amount.
Match the two.

After the fixing jig 1 is arranged at a predetermined position and has a predetermined posture, a molten or semi-molten thermoplastic resin 50 is poured into the frame 20 of the fixing jig 1. Next, the work 30 is lowered to enter the thermoplastic resin 50, and as shown in FIG.
Stop at a position where the 0 side is almost buried. The positional relationship between the processing work 30 and the fixing jig 1 is controlled by the positioning control device so as to be a position according to a set value. The thermoplastic resin 50 is cooled and solidified while maintaining the state. The work 30 and the fixing jig 1
2 may be arranged at the position shown in FIG. 2, and then the molten thermoplastic resin 50 may be injected into the frame mold 20.

After the thermoplastic resin 50 has hardened, the frame mold 20
Is removed from the block jig 10. As a result, as shown in FIG. 3, the block material 51 made of a thermoplastic resin is fixed on the receiving plate 12 of the block jig 10, and the work 30 is inclined at a predetermined inclination angle with respect to the block jig 10. Is fixed in a state of being buried in the block material 51 with the astigmatic axis direction.

In the cutting step, for example, a cutting device having a cutting wheel 150 shown in FIG. 8 is used. For example, the block jig 10 is arranged on the block jig fixture of the cutting device, and the separation distance between the cutting foil and the work is adjusted while changing the position of the concave surface of the work 30 with respect to the fixed cutting wheel 150. To form a concave portion for correcting astigmatism. In this cutting, the block material 51 is also cut at the same time.

FIG. 4 shows the final shape of the workpiece 31 and the block material 52 in the case of a knife-etching process by eliminating the edge thickness. The entire side surface of the work 30 is cut from the original work 30 shown by the broken line before cutting, and the cutting is advanced to a state in which the diameter is smaller than that of the original work 30 to manufacture the lens 31 having an extremely reduced thickness. It is an example.

The work piece cut into a predetermined shape is polished on the concave surface by using a polishing apparatus as shown in FIG. 10 while being fixed to a block jig, and the processed surface is mirror-finished. .

After the polishing step, the block material 52 is heated with, for example, hot air, hot water, or the like, and is melted or dissolved in a solvent to perform a deblocking step of removing the work 31 from the block jig 10, and then forming a lens. The workpiece with the completed shape is cleaned, inspected, and sent to the next process. The thermoplastic resin used as the block material 52 is:
What has been melted when the work 31 is removed can be reused immediately, and the cutting powder cut together with the work 31 is heated to be separated from the cutting powder of the work, which is a thermosetting resin, and re-used. Can be used.

As the thermoplastic resin constituting the above-described block material, the work 30 is fixed to the fixing jig 1 and is cut and polished together with the work 30 in a cutting step or a polishing step. It is preferable that the material has good properties, has a high adhesive strength, a low heat shrinkage rate, is easy to clean for removal of a substance adhered to a work, and is easy to collect after use. Softening point is 50 to 150 from workability
C., particularly preferably in the range of 60 to 110C. As such a thermoplastic resin, for example, paraffin, EVA, or various waxes obtained by mixing pine tar and the like with a dense wax can be suitably used. Examples of the wax include Shift Wax 663, Acwax 442 and the like.

According to the method of manufacturing a plastic lens described above, in the blocking step of fixing the work 30 to the fixing jig 1, the prism ring, which had to be prepared in large numbers, is no longer necessary, and the diameter of the lens is reduced. It suffices to prepare several types of frame molds 20 according to the requirements. In addition, it becomes possible to use a positioning control device, complete automation can be performed by numerical control, and the productivity of the blocking step, which has been a manual operation, can be greatly improved.

In the cutting step, the entire convex surface of the work 30 is fixed by the block material 51, and further the block material 5 is fixed.
Since 1 is supported by the receiving plate 12 of the block jig 10, the outer peripheral portion of the work 30 is not bent by the pressing force of the cutting roll as in the related art, and the precision of grinding is greatly improved. In particular, in the case of knife etching as shown in FIG. 4, since the block material 51 is cut together with the work 30, the peripheral edge of the work 30 is always a block material even if the thickness of the outer peripheral portion of the work 30 is reduced. It is fixed at 52. Therefore, since the thickness of the block material 52 and the thickness of the receiving plate 12 of the block jig 10 support the work 31, even if the periphery of the work 31 becomes a knife-etch, the work 31 does not bend and is accurately bent. Cutting can be performed.
Further, not only the peripheral edge of the processed workpiece but also the grinding accuracy of the central portion is improved with the improvement of the cutting accuracy of the peripheral edge. As a result, even in knife etching, it is possible to perform cutting with the same cutting accuracy as a lens having a normal edge. Therefore, it is not necessary to change the setting of the cutting conditions depending on the shape, the processing conditions are simplified, and automation is facilitated.

Further, in the polishing step, as in the prior art, the peripheral edge of the processed workpiece having been knife-etched is fixed to the blocking material and does not bend by the pressing force of the polishing jig as in the case of cutting. In addition to preventing damage to the polishing jig, the occurrence of defects such as chipping and cracking of the processed work, sagging of the outer peripheral portion and residual polishing is reduced, and accordingly, the occurrence of defects that the chipped surface of the processed work is reduced. .

In the method for manufacturing a plastic lens, the blocking step, the cutting step, the polishing step, and the deblocking step can be automated, so that these steps can be consistently automated.

In the above description, the work has been described as an example in which the lens surface of the multifocal lens is formed on the convex surface side.
The method of the present invention is applicable to cutting any kind of plastic lens. Further, although the concave side is cut, it is of course possible to fix the concave side to a jig and process the convex side.

In the case where the work piece is fixed by inclining the fixing jig, an example in which the fixing jig is inclined has been described. However, the same is achieved by keeping the fixing jig horizontal and inclining the suction jig. I can do it.

[0041]

According to the method for producing a plastic lens of the present invention, the blocking step, which has been a manual operation, can be automated by eliminating the prism ring, and the cutting precision and polishing precision can be improved regardless of the lens shape. And a high quality plastic lens can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 shows an example of a fixing jig for fixing a work to be used in a method of manufacturing a plastic lens according to the present invention.
(A) is a plan view and (b) is a cross-sectional view.

FIG. 2 is an explanatory view showing a method of fixing a work and a fixing jig with a thermoplastic resin.

FIG. 3 is a cross-sectional view showing a state in which a work is fixed to a fixing jig with a thermoplastic resin.

FIG. 4 is a cross-sectional view showing a state in which a workpiece is knife-etched by the method of the present invention.

5A and 5B show a fixing jig used in a conventional blocking step, wherein FIG. 5A is a plan view and FIG. 5B is a cross-sectional view.

6A and 6B show a state in which a processing work is fixed to a fixing jig in a conventional blocking step, wherein FIG.
(B) is a sectional view.

FIG. 7 is a cross-sectional view showing a state in which a processed work is fixed to a block jig with a low melting point metal in a conventional blocking step.

8 is a cross-sectional view showing a state in which a work to be processed fixed to the block jig shown in FIG. 7 is cut.

FIG. 9 is a cross-sectional view showing a state in which a work piece fixed to a block jig by a conventional blocking method is knife-etched.

FIG. 10 is a cross-sectional view showing a state in which a work piece fixed to a block jig is polished by a conventional blocking method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixing jig, 10 ... Block jig, 11 ... Fitting part, 1
2 ... receiving plate, 20 ... frame type, 30 ... processed work, 40 ... suction jig, 50 ... thermoplastic resin, 51 ... block material

Claims (4)

[Claims] 1. A blocking step of fixing one entire surface of a resin-made processing work to be a plastic lens to a block jig via a thermoplastic resin; and disposing the block jig in a cutting device and performing the processing. Cutting the other surface of the workpiece to form a lens surface. 2. The method of manufacturing a plastic lens according to claim 1, wherein in the cutting step, the thermoplastic resin is also cut at the same time. 3. The blocking step comprises forming a box-shaped fixing jig by combining a frame mold and the block jig,
3. The method according to claim 1, further comprising: pouring the melted thermoplastic resin into the fixing jig, arranging the work, solidifying the thermoplastic resin, and then removing the frame from the block jig. Manufacturing method of plastic lens. 4. The method of manufacturing a plastic lens according to claim 1, wherein, in the blocking step, the workpiece is fixed to the block jig with an inclination.