JPS61125760A - Blend processing method for die for forming double-focus lens - Google Patents

Abstract

PURPOSE:To provide the whole circumferential edge with uniform mirror surface in high precision by rotating a metal die around the center of a small lens, by pressing a lap, which makes see-saw motion with the edge neighborhood as its fulcrum while reciprocating, to the edge of the joint part, and thereby eliminating surface defects and optical distortion. CONSTITUTION:A metal die holder 4 rotates a metal die 3 around the center of a small lens 1, and a lap 7 is coupled with a reciprocative mechanism 5 through a rotatable pin 6 fixed to the tip of a reciprocating mechanism 5 having an eccentric wheel 11 so as to produce a reciprocative and a see-saw motion in the neighborhood of the edge part of said small ball 1. This see-saw motion made freely with the edge neighborhood as its fulcrum provides free lapping motion from the tangential line of one sphere to another without application of any force of mechanical motive. Also the blend width and blend form can be changed to a certain degree by altering the see-saw angle and the stroke of reciprocation individually. This will give a mirror surface of extra high order, substantially free of steps, striation, optical distortion, etc.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention is a method of blending the joining edges of two spherical surfaces of a convex mold for molding a bifocal lens with small circular beads, making it unobtrusive. This relates to a new processing method for rounding.

(Prior Art) Figures 2 and 3 are a plan view and a front view, respectively, showing an example of a mold, in which 1 shows a small ball, 2 an edge portion, and 3 a mold, respectively.

4 and 5 are schematic diagrams of an apparatus for explaining the conventional blending method, and FIG. 6 shows the mold surface obtained by the method shown in FIGS. 4 and 5. This is an enlarged view.

The need to blend the two spherical surfaces of a bifocal lens in an inconspicuous manner is a natural requirement in the field of fashionable eyeglass lenses, but this type of processing method for plastic lens molds is There is no one that has been completed so far, but if you force it, you can rotate the mold around the center of the small ball and press it against the processing area with A6 hand wrap or an ultrasonic wrapper to perform blending processing, B, A.
Instead of holding the mold 3 by hand as shown in Figure 4,
is mechanically supported by a mold holder 4, and while the mold holder 4 is rotated about a rotating shaft 9, a reciprocating motion is applied to an ultrasonic wrapper 8 attached to a reciprocating mechanism 5 to perform blending processing. C9 As shown in Fig. 5, the radius of curvature is intermediate between the radii of curvature of the two spheres of the mold 3 (radius of curvature of the large ball (R+), radius of curvature of the small ball (R2)), that is, R1 < in Fig. 5. There is a method of blending using a wrap 10 with R<R2.

(Problems to be Solved by the Invention) However, the above method A has low work efficiency because it is done manually, and it is not possible to uniformly blend the entire circumference of the joint of the two balls, and this process takes a long time. During the seed work, he loses his attention and ends up damaging the spherical surface he has painstakingly polished.

In addition, in methods B and C, as shown in FIG. 6, the first edge E disappears, but new edges E' are created on both sides of edge E.
, E" are formed on both sides (here, the radius of curvature R of AA' is infinite in method B).

In other words, the conventional technology is insufficient as a mold blending method for products that have strict inspection standards such as eyeglass lenses.

The purpose of the present invention is to eliminate the deficiencies of the prior art as described above,
It is an object of the present invention to provide a method for easily blending the edge of the joint between two spheres of a mold for bifocal lenses without surface defects or optical distortion, and in a uniform and highly mirror-like state over the entire circumference of the edge. It's about doing.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following configuration.

That is, in a blending method for a mold for molding a bifocal lens, the mold is rotated around the center of a small ball, and while making a reciprocating motion on the edge of the joint of two spheres of the bifocal lens, and This is a blend processing method for a mold for forming a bifocal lens, characterized in that processing is carried out by pressing a lap that freely seesaws around the edge portion as a fulcrum.

In other words, it combines the two effects of a mirror-finishing effect similar to super-finishing using the rotating mold processing section and reciprocating laps, and a blending process between two spherical surfaces in a natural curve using free seesaw movement. This is how the above objective is achieved.

The present invention will be explained in more detail based on the drawings.

The present invention provides a blending method for uniformly rounding the edge portion 2 to a mirror surface so as not to be noticeable over the entire circumference.

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method of the present invention.

In the figure, 4 is a mold holder, which rotates the mold 3 about the center of the small ball 1 as an axis. On the other hand, lap 7 is eccentric wheel 1
1 is connected to the reciprocating mechanism 5 through a freely rotating bottle 6 attached to the tip of the reciprocating mechanism 5, so that reciprocating movement and seesaw movement are performed near the edge of the small ball 1. It is.

FIG. 7 is an enlarged view of the wrap portion for explaining the movement of the wrap 7.

In FIG. 7, the lap 7 is shown separated from the polishing surface for ease of understanding. As shown in FIG. 7, the wraps 7 come into contact near the edge E and perform a reciprocating motion and a seesaw motion at an angle γ. Note that the angle γ of the seesaw movement can be changed by changing the position of the eccentric wheel 11 from the position shown by the solid line to the position shown by the broken line shown in FIG.

As the reciprocating mechanism 5, a heart cam may be used instead of the eccentric wheel 11 shown in FIG. 1, but this is not preferable because the stroke adjustment mechanism becomes complicated and the vibration becomes large.

FIG. 8 is a diagram showing an embodiment of the reciprocating I7J mechanism,
(i) is a front view, and (b) is a plan view.

In the present invention, a reciprocating mechanism including a blend position adjustment mechanism using a differential screw 12 and an eccentricity (stroke width) adjustment mechanism 13 using a dovetail groove shown in FIG. 8 is preferably used.

Returning to FIG. 1, the wrap 7 comes into contact with the vicinity of the edge part and performs a reciprocating motion and a seesaw motion, but here the relationship between the number of rotations of the mold 3 and the number of reciprocating strokes of the wrap 7 is linear due to the abrasive grains. In order to obtain a scratch-free mirror surface, it is desirable to select a value such that the intersection angle α of the trajectory of the abrasive grains is between 30'' and 60°.

Figure 9 (a) shows the trajectory of the abrasive grains in the blend processing section (
FIG. 9'(b) is an enlarged view of the trajectory of the abrasive grains. The intersection angle α is the angle shown in FIG. 9, and approximately, the relationship between the stroke number 5 (St) Ill) and the work shaft rotation speed N (rilm), and the average cutting speed of the abrasive grains is 1 to 3011Z. It is desirable to set the value to about minutes.

Here, the abrasive grains refer to an abrasive material interposed between the lap 3 and the edge 2 of the mold 3.

As the abrasive grains, materials such as aluminum oxide, chromium oxide, and diamond paste can be used, but diamond paste is the best in terms of processing efficiency.

Further, it is desirable that the pressing force of the lap against the mold edge is 50 g to 1000 o in terms of polishing efficiency and polishing surface degree.

The extremely important point of the present invention is to perform a free seesaw movement using the vicinity of the edge as a fulcrum, so that no mechanical force is applied, and moreover, the two balls can wrap freely from tangent to tangent to each other. Do some exercise. Further, by individually changing the seesaw angle and reciprocating stroke amount of this seesaw movement, the blend width and blend shape can be changed to some extent.

(Effects of the Invention) Since the present invention has the above-mentioned configuration, it exhibits the following excellent effects.

That is, first of all, by using equipment, uniform processing can be easily performed with high efficiency compared to manual finishing. Furthermore, due to the structure of the rotation of the mold and the reciprocation of the lap, a superfinishing-like effect is produced, and an extremely high level of mirror surface can be obtained. By using a seesaw motion in addition to the reciprocating motion, edges can be blended cleanly with almost no steps, streaks, optical distortions, etc.

Example The test was carried out using the apparatus shown in Figure 1 under the conditions shown in the table below.

As a result, it was possible to achieve a blending process that was uniform over the entire circumference of the edge, had almost no surface defects, and was free from optical distortion.

table

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the blend processing method according to the present invention. FIG. 2 is a plan view of an example of a mold used in carrying out the method according to the present invention, and FIG. 3 is a front view thereof. Figures 4 and 5 are
FIG. 6 is a schematic diagram of an apparatus for explaining a conventional blending method, and FIG. 6 is an enlarged view of the mold surface obtained by the method of FIGS. 4 and 5. FIG. 7 is an enlarged view of the wrap portion for explaining the movement of the wrap 7. FIG. 8(a) is a front view showing one embodiment of the reciprocating mechanism;
Figure (B) is a plan view of Figure 8 (A). Figure 9 (a)
9 is a diagram showing the locus of abrasive grains, and FIG. 9(b) is an enlarged view of the abrasive grain locus of FIG. 9(a). Brief description of the drawings 1; Small ball 2: Edge 3; Mold 4; Mold holder 5; Reciprocating mechanism 6; Bin

Claims (1)

[Claims] In a blending method for a mold for molding a bifocal lens, the mold is rotated around the center of a small ball, and while reciprocating the edge of the joint between two spheres of the bifocal lens, A method for blending a mold for molding a bifocal lens, characterized in that processing is carried out by pressing a lap that makes a free see-saw movement using the vicinity of the part as a fulcrum.