JPH0467918A - Method and apparatus for molding plastic lens - Google Patents

Abstract

PURPOSE:To prevent a gate mark and a flange piece from remaining by filling two molds constituted separately with a resin and curing the resin in one mold and matching the cured resin with the uncured resin in the other mold so as to position the optical surface thereof on the outside and curing the uncured resin. CONSTITUTION:Molds 3, 4 are held to room temp. and a thermosetting resin 20 is injected in the respective molding cavities 1, 2 of the molds 3, 4 is proper quantities from the corresponding resin injectors 13, 14. A temp. control medium 11 heated to high temp. is supplied to the temp. control pipe 9 of the mold 3 in which the thermosetting resin 20 is injected to heat the mold 3 and the injected thermosetting resin 20 is cured to obtain a half lens 22. The thermosetting resin 20 injected in the mold 4 is set to an uncured state without heating the mold 4. Since the half lens 22 comes into contact with the uncured thermosetting resin 20 from the surface top part of the convex thermosetting resin 20 from the surface top part of the convex surface 23 thereof, the mixing of air with the space between the lens 22 and the resin 20 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic lens molding method and a plastic lens molding apparatus used in the molding method.

[Prior Art] Injection molding is a known method for molding plastic lenses. That is, a lens-shaped cavity is formed in a mold, molten resin is injected into the cavity through a gate, and the mold is cooled to harden the resin to mold a plastic lens. This type of injection molding requires a gate to serve as an inlet for the molten resin, so a thick part or flange remains at the end of the molded plastic lens as a mark of the gate, making it difficult to use for cameras, endoscopes, etc. This makes it unsuitable for implementation in equipment whose size is limited. Therefore, it is necessary to mold plastic lenses without leaving gate marks.
A device such as that disclosed in Publication No. 19 is developed.

FIG. 11 shows this molding device, in which a pair of molds 1
01 and 102 form a lens-shaped cavity 103
A runner 104 for injecting molten resin into the cavity 103 is formed above the cavity 103. In this device, mold 1
01 and 102 to form a gate I05 that communicates the runner 104 and the cavity 103,
Molten resin is injected into the cavity 103 from the runner 104 through the gate 105, and then the mold is clamped to separate the runner 104 and the cavity 103 as shown in the figure and eliminate the gate 105, leaving no trace of the gate. I try not to leave any residue behind.

FIG. 12 shows a molding device that is a further improvement on this conventional technique, in which a flange 1 is formed on the outer peripheral surface of a lens-shaped cavity 103.
06 to prevent damage to the mold.

[Problem to be solved by the invention]

However, in the conventional molding apparatus shown in FIG. 11, the end 10 of the cavity corresponding to the part where the lens optical surface changes.
7 needs to be a knife edge, which causes the problem that this end portion 107 is easily damaged. On the other hand, in the molding apparatus shown in FIG. 12, since the flange 106 is formed, there is no need for a knife, but there is a problem in that the flange piece corresponding to the flange 106 remains on the plastic lens.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a molding method and a molding apparatus for the same, which can easily mold a plastic lens without leaving gate marks or flange pieces. With the goal.

[Means to solve the problem]

In order to achieve the above object, the molding method of the present invention includes the steps of filling two separately constructed molds with resin, curing the resin in one mold, and displacing the optical surface of the hardened resin on the outside. It is characterized by comprising a step of combining the uncured resin in another mold so as to be located at the same position as the mold, and a step of curing the uncured resin.

Moreover, in order to achieve the above object, the molding apparatus of the present invention includes:
A mold for molding a half lens having one optical surface of a plastic lens, a mold for molding a half lens having the other optical surface of a plastic lens, and a molded half lens having one optical surface and the other optical surface. and a means for integrating a half lens having a half lens.

[For production]

According to the molding method of the present invention having the above configuration, a half lens having one optical surface can be molded by curing the resin in one mold. In addition, by combining this half-lens with the resin of the other mold so that the optical surface is located on the outside, and curing the resin of the other mold, it is possible to mold a plastic lens in which the half-lenses are integrated with each other. can.

Further, according to the molding apparatus of the present invention having the above configuration, since it has means for integrating half lenses having optical surfaces,
This is an apparatus that can suitably implement the above molding method.

〔Example〕

Embodiments of the present invention will be specifically described below with reference to the drawings. In addition, in each embodiment, the same elements are given the same reference numerals and corresponded to each other, thereby omitting redundant explanation.

(First Embodiment) FIGS. 1 to 3 show a first embodiment of the present invention. The molding apparatus of this embodiment includes separately constructed molds 3 and 4, as shown in FIGS. 1 and 2.

These molds 3 and 4 have molding recesses 1 and 2 formed on their upper surfaces, respectively.
The bottom surface of the lens molds the optical surface 5.6 of the plastic lens. These molds 3 and 4 mold a half lens of a plastic lens by filling the respective molding recesses 1 and 2 with resin.

Furthermore, temperature control tubes 9 and 10 are formed through the molds 3 and 4, respectively. The temperature control tubes 9 and 10 are connected to respective temperature control machines (not shown), and fluid such as oil set to an arbitrary temperature is supplied from each temperature control machine, whereby molds 3 and 4 are individually controlled. , independent temperature adjustment is possible.

An upper mold 21 is arranged above one of the molds 3. This upper mold 21 is connected to an air cylinder (not shown) via a support rod 21a, and is movable in the vertical direction by driving the air cylinder. The upper mold 21 has one resin injection path in the vertical direction whose outlet portion faces the molding recess I of the mold 3.
At the same time, a resin injector 13 filled with thermosetting resin 20 is attached to the upper surface of the resin injector 13, and by feeding fluid such as air into the resin injector 13 and pressurizing it, the thermosetting resin 20 is molded. It can be injected into the molding recess 1 of No. 3. In this case, the upper mold 21 at the outlet of the resin injection path
The lower surface of is formed into a concave surface.

Furthermore, the mold 3 is connected to a rotating shaft 16 via a connecting rod 15. The rotating shaft 16 rotates together with a large-diameter driven sprocket 17.
The rotation of the mold 6 rotates the mold 3 so that it collides with the mold 4.

The rotation of the rotating shaft 16 is controlled by the small diameter drive sprocket 1.
A chain (or belt) 19 is connected between the drive sprocket 18 and the driven sprocket 17 on the rotating shaft 16 side.
The hangings are passed endlessly. Furthermore, when the molds 3 and 4 collide with each other due to the rotation of the rotating shaft 16, it is necessary to align the molding recesses 1 and 2, and for this reason, a taper pin 7 is formed protruding from the upper surface of the mold 3. Along with
A tapered hole 8 into which the taper pin 7 fits is formed in the lower surface of the mold 4.

In contrast to such mold 3, the other mold 4 is fixed to the main body of the apparatus, and a resin injector 14 filled with thermosetting resin 20 is disposed above it.

The resin injector 14 is connected to an air cylinder (not shown) via the support port 7 door 14a, and is movable to retreat from above the mold 4 by driving the air cylinder.

The resin injector 4 functions to push the thermosetting resin into the molding recess 2 of the mold 4 by feeding fluid such as air and pressurizing the inside thereof.

Next, a method of molding a plastic lens using this molding apparatus will be explained.

In the state shown in FIG. 1, the molds 3 and 4 are kept at room temperature, and the corresponding resin injectors 13 and 14 are inserted into the molding recesses 1 and 2 of the molds 3 and 4, respectively.
Thermosetting resin 20 from 'iI! Inject 1 amount. At this time, the thermosetting resin 20 stored in the resin injector is pressurized with a gas such as air, and the amount of thermosetting resin 20 injected can be controlled by controlling the pressure and pressurization time. . The injected thermosetting resin 2 is heated by supplying the temperature regulating medium 11 heated to a high temperature to the temperature regulating tube 9 of the mold 3 into which the thermosetting resin 20 is injected and heating the mold 3.
0 is cured to obtain a half lens 22. At this time, the upper mold 21
is not heated, and the resin in the resin injection path is not cured, leaving it ready for the next injection.

On the other hand, the mold 4 is not heated (the injected thermosetting resin 20 is left in an uncured state).The half lens 22 hardened and molded in the mold 3 has a shape as shown in FIG. A convex surface 23 is molded on the back side of the optical surface. After molding the half-I nons, the upper mold 21 and the resin injector 14 are respectively retracted in the direction of the arrow in FIG. 1. Then, they are driven by a motor. By rotating the subrokent 18, the mold 3 is rotated in the direction of the mold 4. When the mold 3 is rotated, the mold 3 is turned upside down, but the half lens 2 in the molding recess l
2 and the optical surface 5 are in close contact with each other without a gap, and there is no air between them. Therefore, the weight of the half lens 22 is held in the molding recess 1 at atmospheric pressure, and it falls from the mold 3. Never.

As the mold 3 rotates, the taper pin 7 fits into the tapered hole 8, and the molds 3 and 4 are positioned relative to each other, whereby the half lens 22 of the mold 3 is placed in the molding recess 2 of the mold 4 in an inverted state. and is brought into contact with the uncured thermosetting resin 20 in the recess 2 . At this time, since the half lens 22 contacts the uncured thermosetting resin 20 from the top portion of its convex surface 23, it is possible to prevent air from entering between them.

Additionally, the thermosetting resin 2 is injected into the mold 4 by the resin injector 14.
By controlling the injection amount to zero, the thermosetting resin 20 in the mold 4 will not be pushed by the half lens 22 and overflow from the mold 4. After that, the temperature control medium heated to a high temperature is transferred to the temperature control tube 10.
By heating the casting mold 4, the thermosetting resin 20 in the mold 4 is cured. By this curing, a half lens having an optical surface is molded, and this half lens and the half lens 22 of the mold 3 are integrated to form a plastic lens having optical surfaces on both sides.

In the first embodiment, a plastic lens can be molded without leaving any gate marks or flange pieces, and the relative positioning of the molds 3 and 4 can be determined by fitting the taper pin 7 and the tapered hole 8. Therefore, the misalignment between the optical surfaces 5 and 6 of these types can be made extremely small. In addition, since the back surface of the half lens 22 molded in the mold 3 is molded into a convex surface, and this convex surface is combined with the uncured thermosetting resin in the mold 4, air may enter or remain between them. It is possible to mold good plastic lenses without any problems.

4 and 5 show a modification of this first embodiment. A half lens 22 whose tip portion is inside the molding recess of the mold 3
A stopper 24 or a plurality of stoppers 24 that come into contact with the outer peripheral portion of the mold 3 are attached so as to be movable forward and backward in the circumferential direction of the mold 3.

This stopper 24 is urged to move in the direction of contact with the outer peripheral portion of the half lens 22 by a spring 25, and due to the contact with the half lens 22, the half lens 24 is moved when the mold 3 is rotated.
This prevents the objects from falling. The stopper 24 also slides in the retracting direction with respect to the half lens 22.

For this purpose, a pin hole 24a is formed in the stopper 24 in an oblique direction, and a pin 26 to be inserted into the pin hole 24a is formed to protrude in the diagonal direction at a position opposite to the mold 4. The pin 26 is inserted into the bottle hole 24a when the mold 3 collides with the mold 4, so that the stopper 24 is retracted from the half lens 22 when the molds 3 and 4 collide (see FIG. 5). , without interfering with the integration of the half lenses.

Note that a recess 11 into which the stopper 24 is inserted is formed on the upper surface of the mold 4 corresponding to the stopper 24;
A similar recess (not shown) is also formed in the upper mold 21 that contacts the mold 3 from above.

By providing such a stopper 24, it is possible to reliably prevent the half lens 22 from falling. For example, when molding a plastic lens with a large self-weight such as a large diameter lens or a lens with a large specific gravity, the half lens 22 can be prevented from falling. Fall prevention can be performed.

(Second Embodiment) FIGS. 6 to 8 show a molding apparatus in a second embodiment of the present invention.

As shown in FIG. 6, in this molding apparatus, both molds 3 and 4 are fixed to the main body, and a chuck 27 is disposed between these molds 3 and 4. As will be described later, the chuck 27 chucks the half lens 22 that has been hardened and molded in the mold 3, and also holds the half lens 22 at 180 mm in this chuffed state.
The half lens 22 is reversed by one rotation, and is connected to a suitable motor.

In addition to such a chuck 27, a slider 12 is provided above the molds 3 and 4. The slider 12 is driven above the molds 3 and 4 to reciprocate between them, and a suction device 28 is attached to the slider 12 so as to move integrally therewith.

The suction device 28 takes out the hardened and molded half lens 22 from the mold 3 and conveys it to the chuck 27.
The half lens 22 that has been inverted by the rotation is conveyed to the molding recess 2 of the mold 4. To carry out these operations, the suction device 28 is moved up and down by an air cylinder or the like.

Next, a method of molding a plastic lens using the molding apparatus of the second embodiment will be explained. After injecting the thermosetting resin 20 into the molding recess 1 of the mold 3, 20 thermosetting resin 2
0 is heated and cured while applying a predetermined pressure from the resin injector 13. This pressure can be adjusted by controlling the pressure of the gas sent to the resin injector 13. During curing in this mold 3, the thermosetting resin 20 in the resin injection path of the upper mold 21 is not cured, as in the first embodiment.

On the other hand, the resin injector 1 is also placed inside the molding recess 2 of the other mold 4.
4, a predetermined amount of thermosetting resin 20 is injected. By curing the thermosetting resin 20 in the mold 3, a half-lens similar to 22 shown in FIG. 3 is molded (FIG. 7), and this half-lens is sucked by a sucker 28, which is then moved upward. By this,
Release the half lens from the mold 3. Then, the half lens is conveyed to the chuck 27, the chuck 27 is chucked, and the suction device 28 is separated from the half lens. After that, the chuck 27 rotates 180'', so that the half lens is turned upside down by the chuck 27, so that the surface on which the optical surface 5 has been transferred is placed on top.
to release the chuck from the chuck 27.

Next, the half lens sucked by the suction device 28 is moved above the molding recess 2 of the mold 4, the suction device 28 is moved downward, and the half lens is transferred to the uncured thermosetting resin 20 of the mold 4. Bring it into close contact. This half-lens can evenly apply pressure to the thermosetting resin 20 in the mold 4 through its convex surface 23. In this state, the mold 4 is heated to harden the unhardened thermosetting resin 20 and are integrated with the half lens to form a plastic lens (FIG. 8).

In this case, the pressure applied to the thermosetting resin 20 in the mold 4 is determined by the force of the adsorber 28 pushing the half lens, the size of the convex surface 23 of the half lens (i.e., the concave surface of the upper mold 21), and the pressure applied to the thermosetting resin 20 in the mold 4.
The amount of thermosetting resin rIri20 injected can be arbitrarily changed. According to the second embodiment, after inverting the half lens and producing the plastic lens, the thermosetting resin 20 for the next stage molding is injected into the mold 3, and the next stage molding is performed within the mold 3. A half lens can be made.

Therefore, it is possible to shorten the takt time.

Furthermore, since pressure is applied to the thermosetting resin 20 in the molds 3 and 4, the transfer accuracy of the optical surfaces 5 and 6 of the molds 3 and 4 is improved, making it possible to mold lenses with high precision. .

In the first and second embodiments as described above,
It is also possible to use thermoplastic resins instead of thermosetting resins. In this case, when injecting the thermoplastic resin into the other mold 4, by heating the mold 4 and keeping the surface temperature of its optical surface 6 higher than the melting point of the thermoplastic resin,
After bringing the half lenses together in an uncured state, the mold 4 is cooled and the thermoplastic resin is cured to form a plastic lens. In addition, in the case of the first embodiment, types 3 and 4
Alternatively, an ultraviolet curable resin can be used by making the upper mold 21, or the mold 3 or the upper mold 21 in the case of the two-force cylinder 2 embodiment, from a material that can transmit ultraviolet rays, such as glass.

(Third Embodiment) FIGS. 9 and 10 show a molding apparatus according to a third embodiment of the present invention. In this molding device, a molding recess 1 for molding one optical surface is formed on the upper surface of one lower mold 33, and a molding recess 2 for molding the other optical surface is formed in the other lower mold 34, These lower molds 33 and 34 have an upper mold 35,
36 are arranged facing each other. In addition, these lower molds 33.3
4 is vertically movable relative to the upper molds 35 and 36.

In addition, the upper mold 35, 36 has a gate 37 for injecting resin 39 into the molding recess 1.2 of the opposing lower mold 33, 34.
．． 38 is formed. These gates 37 and 38 are mechanisms (not shown) for plasticizing and injecting the thermoplastic resin 39, such as screws and cylinders of general injection molding machines.
The plasticized resin 39 is injected into each molding recess 1.2. In this case, a conical recess 40 is formed at the resin outlet portion of the gate 37 of one of the upper molds 35 . moreover,
Near the other lower mold 34, an ultrasonic transmitter 41 equipped with a horn 42 is provided so as to be movable vertically and horizontally, and below this ultrasonic transmitter 41, a positioning jig 43 is movable vertically and horizontally. possible.

In this third embodiment, a plastic lens is molded by injection molding, and includes lower molds 33, 34 and upper molds 35.3.
6 and 6 are clamped together, resin is injected to mold half lenses 44 and 45, respectively.

In this case, a small conical protrusion corresponding to the recess 40 is formed on the half lens 44 formed by one of the lower mold 33 and the upper mold 35. This half-lens 44 is superimposed on the half-lens 45 of the other lower mold 34 with the small protrusions facing down, using the chuck 27 and suction device 28 as in the second embodiment. At this time, the half lens 44 is
and the half lens 45 so as to align the center of the half lens 44
to be fixed.

After that, the horn 42 is brought into contact with the upper surface of the half lens 44,
Ultrasonic vibrations are applied from an ultrasonic transmitter 41 to the half lens 44 through the horn 42, and the half lenses 44 and 45 are welded around the small protrusion of the half lens 44. Thereby, the half lenses 44 and 45 can be integrated to form a plastic lens.

In this embodiment, since the half lens is molded by injection molding, it is possible to mold a plastic lens on which the optical surface is transferred with high precision.

〔Effect of the invention〕

As described above, according to the molding method of the present invention, it is possible to easily mold a plastic lens without leaving gate marks or flange pieces. Moreover, according to the molding apparatus of the present invention, the above molding method can be carried out suitably.

[Brief explanation of drawings]

The first part is a side sectional view showing the first embodiment of the molding device of the present invention, the second part is a side sectional view showing its operation, the third part is a sectional view showing a molded half lens, and the fourth part is FIG. 5 is a cross-sectional view showing a modification of the first embodiment and a cross-sectional view of its operation, FIG. 6 is a partially cutaway side view showing a second embodiment of the molding apparatus of the present invention, and FIGS. 7 and 8 9 and 10 are sectional views showing a third embodiment of the molding apparatus of the present invention and sectional views showing its operation, and FIGS. 11 and 12 are sectional views showing the conventional molding apparatus. It is a sectional view showing each piece. 3.4... Mold 5.6... Optical surfaces 33, 34... Lower mold Figure Figure ■ ~ 26 Figure Field

Claims (2)

[Claims] (1) The process of filling resin into two separately configured molds, the process of curing the resin in one mold, and the process of filling the resin in the other mold so that the optical surface of the cured resin is located on the outside. A method for molding a plastic lens, comprising a step of combining with a cured resin and a step of curing the uncured resin. (2) A mold for molding a half-lens having one optical surface of a plastic lens, a mold for molding a half-lens having the other optical surface of a plastic lens, and a molded half-lens having one optical surface and the other. 1. An apparatus for molding a plastic lens, comprising means for integrating a half lens having an optical surface.