JP2002337206A - Method for injection/compression molding of spectacle lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for the injection/compression molding of a spectacle lens capable of molding the spectacle lens of high quality with high accuracy regardless of the shape characteristics of the lens. SOLUTION: In the injection/compression molding method, a mold is clamped so as to leave a set compression flap in a cavitry for the lens and the cavity is filled with a molten resin by injection and, before or after the injection filling of the molten resin is completed, the set compression flap is compressed. The set compression flap [little open quantity S (-)] at the time of molding of a minus lens is set so as to become larger than the set compression flap [little open quantity S (+)] at the time of molding of a plus lens. Since a wide cavity region is ensured even at the time of molding of the minus lens, the molten resin passes through the central part of the cavity to flow in the peripheral part of the cavity and, therefore, the generation of a weld mark at the central part of the cavity can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injection compression molding of a spectacle lens for obtaining a spectacle lens by injection compression molding of a thermoplastic resin. More specifically, the present invention relates to an injection compression molding method of a spectacle lens capable of molding a plus lens and a minus lens with high precision and high quality.

[0002]

BACKGROUND ART As a molding method for obtaining a lens from a thermoplastic resin, an injection compression molding method is known (for example, JP-A-2-26723 and JP-B-6-9826). For spectacle lenses, lens power + 4.00D-
A lens having a lens power range of about 8.00D is preferably used in this molding method. The injection compression molding method corrects the shrinkage of the molten resin, clamps the mold while leaving a compression allowance in the lens cavity, and obtains uniform and high shape accuracy. Is a molding method in which a molten resin is injected and filled, and then the compression margin is compressed to obtain a lens.

[0003]

By the way, the lens is
If the curvature is different between the front side and the rear side of the lens, the lens thickness causes a thickness difference, and assuming that there is a thickness difference, a plus lens whose center part is thicker than the peripheral part, and a center part whose thickness is the peripheral part There are two types: a thinner minus lens. The lens thickness differs depending on the design of the optical lens. For example, in the case of an aspherical lens having a refractive index of about 1.50, the center thickness is 4.2 mm at + 2.00D, the peripheral thickness is 1.0 mm, and the center thickness is -4.00D at 1 mm. A design value of about 0.4 mm and a peripheral thickness of about 7.9 mm can be set. However, when compression molding is performed on these lenses under the same conditions, the following problems occur due to the difference in the shape characteristics.

In molding a minus lens, the central portion of the lens is thinner than the peripheral portion, so that the flow resistance is large at the central portion of the cavity. Therefore, the molten resin injected into the cavity is difficult to flow in the central portion of the cavity, and diverges from the peripheral portion to the central portion, so that there is a problem that many weld marks are likely to be generated in the central portion. On the other hand, in molding a plus lens, if the difference between the volume of the cavity and the filling amount of the molten resin is too large, the fluidity of the molten resin is reduced, so that an unfilled portion is generated. A filling history of a resin called a flow mark is likely to occur in a critical portion between the resin and an unfilled portion.

An object of the present invention is to provide an injection compression molding method for a spectacle lens capable of molding a lens having an uneven thickness difference, that is, a plus lens and a minus lens with high accuracy and high quality regardless of the shape characteristics of the lens. Is to do. Another object of the present invention is to provide an injection compression molding method for a spectacle lens that can efficiently mold a plus lens and a minus lens from injection to release.

[0006]

According to the injection compression molding method for a spectacle lens according to the present invention, a mold is formed while leaving a preset compression allowance in a lens cavity space formed from an interchangeable optical insert. In the injection compression molding method of a spectacle lens, the molten resin is injected and filled into the lens cavity, and the set compression allowance is compressed at least after the time before the completion of the injection of the molten resin. The feature is that the set compression allowance when molding a minus lens thinner than the peripheral part is larger than the set compression allowance when molding a plus lens where the center part thickness is thicker than the peripheral part, increasing the fluidity of the molten resin in the cavity. I do. put it here,
The term "at least before the completion of the injection of the molten resin" means a time before the completion of the injection or after the completion of the injection.

In such a molding method, since the set compression allowance at the time of molding the minus lens is set to be larger than the set compression allowance at the time of molding the plus lens, a wider cavity area can be secured and the molten resin in the cavity can be secured. Since the fluidity is also improved, the molten resin that has reached the inside of the cavity flows into the peripheral portion through the center portion of the cavity without being shunted at the time of molding the minus lens. Therefore, it is possible to prevent the occurrence of a weld mark at the center portion, and to maintain a sufficient pressing force with the strength lens, thereby improving the transferability with the mold. Therefore, the plus lens and the minus lens can be formed with high precision and high quality regardless of the shape characteristics of the lens.

Further, in the above-mentioned injection compression molding method, it is necessary to set the set compression allowance at the time of molding the minus lens larger than the set compression allowance at the time of molding the plus lens. At that time, the setting of the compression allowance at the time of molding the minus lens is set in the same way as the setting of the compression allowance at the time of molding the plus lens, from the initial position where the compression allowance in the lens cavity is the maximum to the position where the compression allowance disappears. If the mold is set by further opening the mold by the set compression allowance after the mold is clamped, there is a problem in that the distance to open the mold by the set compression allowance is long and the time is inefficient.

Specifically, in the present invention, in the case of molding a plus lens, the set compression allowance is not large and is set to 0.8 mm or less. For example, for a lens of + 1.00D to + 3.00D, 0.1 mm to 0 mm is set. .2 mm is sufficient. On the other hand, in the case of minus lens molding, the set compression allowance is set to 5 mm to 15 mm, although it differs depending on the power and the performance after molding. Further, in the mold clamping control of the mold, for example, in the vertical molding machine, controlling the upward movement from the maximum compression position (lowest lower limit position) at a pitch of 0.1 mm due to the structure of the molding machine is an advanced control. Requires a long time for control. For example, it may take 10 seconds or more for a movement of 5 mm.
On the other hand, it is easy to move the mold from top to bottom,
Even within one second.

Therefore, in the injection compression molding method for a spectacle lens according to the present invention, the setting of the set compression allowance at the time of molding the plus lens is performed at a position where the compression allowance in the lens cavity is reduced from the initial position where the compression allowance is maximum. After closing the mold until the mold is further opened by the set compression allowance, the setting of the set compression allowance at the time of molding the minus lens is such that the compression allowance in the lens cavity is the maximum. The setting is performed by clamping the mold from the initial position to the position where the set compression margin is left.

In this way, the set compression allowance at the time of molding the minus lens can be set by clamping the mold from the initial position where the compression allowance in the lens cavity is maximum to the position where the set compression allowance is left. In other words, since there is no operation of opening the mold by the set compression allowance for a long distance, the set compression allowance can be set quickly and accurately. On the other hand, the set compression allowance for molding a plus lens is set by closing the mold from the initial position where the compression allowance in the lens cavity is maximum to the position where the compression allowance disappears, and then opening it for a short distance set compression allowance. Since it is possible, similarly, the setting of the set compression allowance can be performed quickly and with high accuracy.

In the above-mentioned injection compression molding method, the set compression allowance at the time of molding the minus lens is set larger than the set compression allowance at the time of molding the plus lens. As a result, the flow of the molten resin stops while leaving a large unfilled part, and a resin filling history called a flow mark occurs in the critical part between the filled part and the unfilled part in the molded lens after the pressing step. There is a problem that it is easy.

On the other hand, in the injection compression molding method for spectacle lenses according to the present invention, the compression of the set compression margin is started after the injection of the molten resin is completed at the time of molding the positive lens. By starting the compression at the set compression allowance before the resin injection is completed, the fluidity and transferability of the resin can be further improved. That is, at the time of molding the minus lens, the compression of the set compression margin is started before the injection of the molten resin is completed, and the volume of the lens cavity is reduced, so that the flowability of the molten resin is increased, and the injection filling of the molten resin is completed. Since a large unfilled portion is less likely to remain in the lens cavity at the time, the occurrence of a flow mark can be prevented.

At this time, at the time of molding the minus lens, the cavity for the lens including the sprue and the runner is immediately made into a closed space after the injection of the molten resin is completed, and at the time of molding the plus lens, before the compression of the set compression allowance is started, If the lens cavity including the sprue and the runner is a closed closed space, even if the molten resin in the lens cavity is pressurized by compression, the molten resin may flow back out of the lens cavity including the sprue and the runner. Because there is no
It is possible to obtain a high-precision, high-quality lens having excellent mold transferability and no striae or ejection history. Particularly, it is useful for molding a strong lens.

[0015] In the injection compression molding method for spectacle lenses according to the present invention, a movable die which opens and closes relative to a fixed die is mounted on a die mounting member and movably mounted on the die mounting member toward the fixed die. And an insert for movably fitted into an insert guide to form a lens cavity is provided inside the mold body, and a holding member for holding the insert is elastic. The member is constantly elastically urged in the opposite direction to the fixed mold and is brought into contact with the mold mounting member, and moves the mold mounting member toward the fixed mold while leaving a preset compression allowance in the lens cavity. The mold is moved forward to clamp the mold, and then the molten resin is injected and filled into the lens cavity, and at least after the time before the completion of the injection of the molten resin, the mold mounting member is moved toward the fixed mold. Advance by compressing the set compression margin,
Thereafter, the mold mounting member is retracted, the movable mold is opened from the fixed mold, and then the holding member is pressed and moved toward the fixed mold with an eject pin inserted into the mold mounting member. In the injection compression molding method for spectacle lenses that protrudes a lens molded product with an insert, the set compression allowance at the time of molding a minus lens where the thickness of the central part is thinner than the peripheral part,
The thickness of the central portion is larger than the peripheral portion, and is larger than a set compression allowance at the time of molding of the plus lens. At the time of retreating the mold mounting member, the eject pin is used to press and move the holding member toward the fixed mold side, thereby making the insert Is moved forward to the fixed mold side relative to the mold mounting member, thereafter, the movable mold is opened from the fixed mold, the holding member is pressed and moved by the eject pin, and the lens is inserted by the insert. It is characterized by protruding a molded product.

According to this molding method, in addition to the effect of preventing the occurrence of weld marks at the central portion, the plus lens and the minus lens can be molded with high accuracy and high quality regardless of the shape characteristics of the lens. The following effects can also be expected. That is, when the movable mold mounting member is retracted, the holding member is pressed and moved to the fixed mold side by the eject pin, whereby the insert advances to the fixed mold side relative to the movable mold mounting member. Therefore, a gap having the same size as the retreat amount of the mold mounting member does not occur between the lens molded product and the insert in the cavity, and therefore, the generation of excessive compressed air can be suppressed, and the lens molded product can be used. It is possible to prevent the pressure of the compressed air from acting. Therefore, there is no mold release defect such as breakage of a part formed by the sprue or runner or deviation from the mold at the time of mold release, and a lens molded product having high molding accuracy can be obtained.

Here, when the movable die mounting member is retracted, the holding member is pressed and moved by the eject pin to advance the insert toward the fixed die relative to the movable die mounting member. The amount of advance may be the same as the amount of retreat (slight opening) of the mold mounting member, and may be large, but smaller is more preferable.

If the amount of advance is smaller than the amount of retreat of the mold mounting member, a gap can be provided between the insert and the lens molded product. Therefore, even when the movable mold is opened from the fixed mold, the lens molded product is removed from the cavity. Without falling off,
Prevents damage to lens molded products due to falling off. In particular, the gap between the insert and the lens molded product is preferably 1 to 4 mm.
If the gap is less than 1 mm, there is a risk that the lens molded product will fall off. If the gap is larger than 4 mm, the effect of suppressing the generation of excessive compressed air is low.

That is, when the fastening force is released after the mold clamping, the compression margin is set to a large value, so that the retraction largely and abruptly retreats. In particular, the molding environment (mainly temperature) on the convex surface side of the lens greatly changes. Therefore, a phenomenon occurs in which a release force is strongly applied to a part of the lens surface to cause a release failure, or a sprue or a runner portion is broken. Therefore, by providing the intermediate ejecting function by setting the above-mentioned gap, it is possible to prevent the partial release action from being excessively applied to a part of the molded part. In particular, in the case of a plus lens, since the peripheral thickness of the lens is small, the strength of the joint with the runner is not structurally strong, so this ejecting method is effective.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a spectacle lens according to the present embodiment (a meniscus-shaped spectacle lens;
FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, showing a mold for injection compression molding used in an injection compression molding method (multifocal, progressive multifocal). The material of the spectacle lens molded here is a thermoplastic resin such as PMMA (polymethyl methacrylate) and PC (polycarbonate). In the present embodiment, low-output ejection is used to prevent striae and optical distortion.

In the injection compression molding mold, as shown in FIG. 1, two spectacle lens cavities 3 are provided between an upper mold 1 and a lower mold 2 which are vertically divided at a parting line PL. This is a mold for taking two formed lenses.

The upper mold 1 is a movable mold that closes and opens the mold vertically with respect to the fixed lower mold 2.
And a mold body 4 movably attached to the mold attaching member 16 toward the lower mold 2. Mold mounting member 16
Consists of an upper member 16A and a lower member 16B. Mold body 4
Consists of an insert guide 5 and template plates 6,7. The lower mold 2 includes a mold body 8 including an insert guide 9 and a mold plate 10, and a mold attachment member 15 to which the mold body 8 is attached. Inserts 11 and 12 forming the cavity 3 are accommodated inside the insert guides 5 and 9 so as to be slidable in a direction perpendicular to the parting line PL.

The mold body 4 of the upper mold 1 is connected to the mold mounting member 16 by bolts 17 shown in FIG. 2, and between the mold body 4 and the mold mounting member 16 is an outer periphery of the bolt 17. The inserted disc spring 17A is interposed. The mold mounting member 16 is moved up and down by a mold clamping cylinder (not shown). A gap S is provided between the mold body 4 and the mold mounting member 16, and the mold body 4 and the mold mounting member 16 are opened and closed up and down by the gap S while being guided by the guide pins 18. It is supposed to. A gap opening cylinder (not shown) is disposed below the mold mounting member 15, and the gap S is formed by the mold opening member 16 being pushed up against the clamping force of the mold clamping cylinder by the opening cylinder. It is supposed to be.

The mold mounting member 16 is provided with a downward hydraulic cylinder 19 so as to be vertically movable. Piston rod 21 connected to piston 20 of hydraulic cylinder 19
Is provided with a T-shaped clamp member 23 at the end thereof, penetrating through the inside of the back insert 22 fixed to the lower surface of the cylinder 19. The T-shaped clamp member 23 includes the insert 1
1 is removably engaged with a T-shaped groove 24 formed on the upper end surface. The mold mounting member 15 is provided with an upward hydraulic cylinder 26. The piston rod 28 connected to the piston 27 of the hydraulic cylinder 26 penetrates through the inside of the mold mounting member 15 and has a T-shaped clamp member 29 at its tip. The T-shaped clamp member 29 is connected to the insert 1.
2 is engaged with a T-shaped groove 30 formed on the lower end surface so as to be freely detachable.

A pressure receiving member 32 is fixed to the upper end of the hydraulic cylinder 19. When the pressure receiving member 32 is pushed down by the eject pin 34 inserted from the hole 33 formed in the mold attachment member 16, the hydraulic cylinder 19, the back insert 22 and the insert 11 are also pushed down, and the lens molded product molded in the cavity 3 is formed. The upper mold 1 and the lower mold 2 are protruded when the mold is divided. Here, a holding member that holds the insert 11 is configured by the back insert 22, the hydraulic cylinder 19, and the pressure receiving member 32. An eject bar 35 is disposed at the center of the mold mounting member 16 of the upper mold 1 so as to be vertically movable. A pressure receiving member 36 is fixed to an upper end of the eject bar 35. When the pressure receiving member 36 is pushed down by the eject pin 38 inserted from the hole 37 formed in the mold attaching member 16, the eject bar 35 is pushed down.

The spring force of the spring 40 wound around the outer periphery of the eject return pin 39 acts on the pressure receiving member 32 upward. Although not shown, the spring force of the spring wound around the outer periphery of the eject return pin also acts on the pressure receiving member 36 in an upward direction. Therefore, when the eject pins 34, 38 rise, the pressure receiving members 32, 36
Has also risen and returned to its former position. here,
The holding member constituted by the back insert 22, the hydraulic cylinder 19 and the pressure receiving member 32 is always elastically urged in a direction opposite to the lower mold 2 by a spring 40 which is an elastic member, and is in contact with the mold mounting member 16. .

Next, the operation of the present embodiment will be described. First, the inserts 11 and 12 are exchanged according to the type of lens to be molded. Inserts 11 and 12
In the replacement, the upper mold 1 including the mold attaching member 16 is raised and the mold is divided from the lower mold 2. Further, the piston rod 21 of the hydraulic cylinder 19 is lowered, and the piston rod 28 of the hydraulic cylinder 26 is raised.
The character clamp members 23, 29 are projected from the insert guides 5, 9.

The mold bodies 4, 8 of the upper mold 1 and the lower mold 2 are newly added.
The inserts 11 and 12 mounted on the insert are horizontally transferred while being held by a robot arm (not shown), and the T-shaped grooves 24 and 30 of the inserts 11 and 12 are inserted into the T-shaped clamp member 2.
3, 29 are engaged. Thereafter, the piston 11 is raised by raising the piston rod 21 of the hydraulic cylinder 19, and the piston 12 is lowered by lowering the piston rod 28 of the hydraulic cylinder 26. This allows
Inserts 11 and 12 are fitted to insert guides 5 and 9. In this manner, in the case of molding a plus lens (a lens having a central portion thicker than the peripheral portion), the inserts 11A and 12A shown in FIGS. 6 and 7, inserts 11B and 12 shown in FIGS.
Exchange each for B.

Now, in molding the lens, the operation proceeds according to the flowchart shown in FIG. First, FIG.
Then, the mold is closed as shown in FIG. That is, the upper mold 1 is lowered by the mold clamping cylinder, and the mold plate 6 of the upper mold 1 is brought into contact with the mold plate 10 of the lower mold 2 and the mold is closed so that the disc spring 17A is not compressed. In this state, the gap S is set to the maximum opening amount (about 15 mm), that is, the compression allowance in the cavity 3 is set to the maximum initial position. Next, an opening amount (set compression allowance) is set. At this time, in the molding of the plus lens, an opening amount S (+) of 0.8 mm or less is set.
In molding of a minus lens, an opening amount S (−) larger than 0.8 mm is set. That is, the set compression allowance at the time of molding the minus lens is set to be larger than the set compression allowance at the time of molding the plus lens.

Here, in the case of molding a plus lens, that is, when the opening amount S (+) of 0.8 mm or less is set, as shown in FIG. Is further lowered (at this time, the disc spring 17A is compressed), and the gap S is completely eliminated. Then, the mold mounting member 16 is opened by the slightly open cylinder against the closing force of the closing cylinder. Raise by S (+), and set the opening amount S (+). On the other hand, in the case of molding a minus lens, that is, when the opening amount S (−) larger than 0.8 mm is set, as shown in FIG. It is lowered to the position where the amount S (-) remains (at this time, the disc spring 17A is compressed), and stopped at that position to set the slightly open amount S (-).

Next, the molten resin is injected and filled. For this, the molten resin is injected from the nozzle of the injection molding machine connected to the sprue bush 57 and the sprue 58 and the runner 5
9 to fill the cavity 3. At this time, in the case of molding a plus lens (FIG. 4), the thickness of the central portion of the cavity 3 (the central portion of the lens) is large, so that the molten resin that has reached the inside of the cavity 3 is Through the center) to the periphery. On the other hand, in the case of molding a minus lens, since the opening S (−) larger than 0.8 mm is set, that is, the thickness of the central portion of the cavity 3 is set large, Reaches the peripheral portion through the central portion of the cavity 3 without shunting. Therefore, in any case, the weld mark at the central portion is suppressed.

Next, in the case of molding a plus lens (FIG. 4)
After the injection of the molten resin is completed, the space including the cavity 3, the runner 59, and the sprue 58 is closed to form a closed space, and then pressurized (compressed). That is, FIG.
As shown in (2), the mold mounting member 16 is lowered by the opening S (+) by the mold clamping cylinder. On the other hand, in the case of molding a minus lens (FIG. 6), pressurization (compression) is started before the injection of the molten resin is completed. Specifically, when about 90 to 95% of the molten resin to be injected has been injected, pressurization is started by the mold clamping cylinder, and as shown in FIG.
6 is lowered by the opening S (-). At this time, the nozzle is closed immediately after the injection of the molten resin is completed, and the space including the cavity 3, the runner 59, and the sprue 58 is made a closed space.

Next, after forming a plus lens or a minus lens in this way, these lenses are ejected. To this end, the mold mounting member 16 of the upper mold 1 is raised by the mold clamping cylinder, that is, raised from the lower mold 2,
An opening amount S is opened between the mold body 4 and the mold body 4. At this time, the eject pin 34 is lowered by the eject cylinder, and the pressure receiving member 32 is moved downward by the eject pin 34 with respect to the mold mounting member 16. This pressing movement amount is smaller than the opening amount S, and the opening amount S is, for example, 15
mm, the amount of pressing movement is 13 mm. In other words, when the mold mounting member 16 is raised, the insert 11
Is lowered toward the lower die 2 relative to the die mounting member 16.

As a result, when the mold mounting member 16 originally rises by the opening amount S, the rising amount of the insert 11 which rises by the same amount can be suppressed small.
For example, in minus lens molding, as shown in FIG.
The insert 11 has a slight gap A from the spectacle lens portion 44A of the lens molded product 44 molded in the cavity 3,
If the opening or pressing movement is the same as the numerical value, 2
It is separated by the gap A of mm.

Thereafter, as shown in FIG. 9, the mold mounting member 16 and the mold body 4 of the upper mold 1 are raised by the mold clamping cylinder, and the upper mold 1 is moved upward.
Is opened from the parting line PL with respect to the lower mold 2. Thereafter, a part of the lens molded product 44 exposed from the lower surface of the upper mold 1 is gripped by the gripping device, and the eject pin 3
4 and 38 are lowered by the respective eject cylinders, whereby the pressure receiving members 32 and 36 are pressed and moved, and the lens molded product 44 is protruded by the insert 11 and the eject bar 35. At the time of this protrusion, the lens molded product 4
Since the insert 11 is only apart from the spectacle lens portion 44A by a small gap A, the air entering the gap A is not compressed to a large pressure by the insert 11, and the compressed air is not compressed. The lens molded product 44 can be protruded from the upper mold 1 without applying a large pressure to the spectacle lens portion 44A.

That is, when the mold attaching member 16 of the upper mold 1 rises from the mold main body 4 by the opening S, the ejecting pin 34 does not press and move the pressure receiving member 32 downward. When the insert 11 is not lowered relatively, the spectacle lens portion 44A of the lens molded product 44
A gap having the same size as the opening size S is formed between the insert 11 and the insert 11, and when the insert 11 projects the spectacle lens portion 44A, the air in this gap is greatly compressed and excessive high-pressure air is generated. Although this acts on the spectacle lens portion 44A, which is a precision molded portion, in the embodiment according to the present invention, a slight gap A can be formed between the spectacle lens portion 44A and the insert 11, so that the insert 11 When the spectacle lens portion 44A of the lens molded product 44 is protruded, it is possible to suppress the generation of excessive compressed air and perform the protruding, and to break the mold at the part formed by the sprue 58 or the runner 59 or to release the mold. A highly accurate molding state of the spectacle lens portion 44A can be ensured without a mold release defect such as displacement.

According to the present embodiment, the opening amount S (-) when molding the minus lens is changed to the opening amount S when forming the plus lens.
Since the value is set to be larger than (+), a wider cavity area can be secured, and the fluidity of the resin in the cavity can be improved. Therefore, at the time of molding the minus lens, the molten resin that has reached the inside of the cavity 3 flows into the peripheral portion through the central portion of the cavity 3 without shunting, so that the occurrence of weld marks at the central portion can be prevented. Therefore, the plus lens and the minus lens can be formed with high precision and high quality regardless of the shape characteristics of the lens.

At this time, it is necessary to set the opening S (-) at the time of molding the minus lens larger than the opening S (+) at the time of molding the plus lens. Since the opening amount S (-) is set by lowering the mold mounting member 16 of the upper die 1 to the position where the opening amount S (-) is left, the opening amount S (-) is set. Can be performed quickly and with high accuracy. On the other hand, the opening amount S (+) at the time of molding a plus lens is the opening amount S (-) at the time of molding a minus lens.
Therefore, in this case, after lowering the mold mounting member 16 of the upper mold 1 from the initial position where the opening amount S is the maximum to the position where the opening amount S disappears, the opening amount S (+) Since the opening amount S (+) is set by opening, the opening amount S (+) can be set quickly and accurately.

Also, at the time of molding the minus lens, compression of the opening S (+) is started before the injection of the molten resin is completed, so that the volume of the cavity 3 is reduced before the injection of the molten resin is completed. Therefore, a large unfilled portion is unlikely to remain in the cavity 3 at the time of completion of the injection and filling of the molten resin, so that the occurrence of a flow mark can be prevented. That is,
If the opening size S (+) is set to a large value, the flow of the molten resin stops while leaving a large unfilled portion in the cavity at the time of completion of the injection filling of the molten resin, and the gap between the filled portion and the unfilled portion Although there is a problem that a filling history of a resin called a flow mark is likely to occur in the critical portion, the occurrence of the flow mark can be prevented by adopting the present embodiment.

When the mold mounting member 16 of the upper mold 1 is lifted from the lower mold 2, the holding member holding the insert 11 provided on the mold body 4 of the upper mold 1 is moved by the eject pin 34 to the lower mold 2. 2 to lower the insert 11 toward the lower mold 2 relative to the mold mounting member 16, so that when the lens molded product 44 is protruded by the insert 11, the generation of compressed air is suppressed. Since the protrusion can be performed, and the pressure of the high-pressure compressed air does not act on the lens molded product 44, the protrusion operation can be performed while securing the molding accuracy of the lens molded product 44 formed with high precision.

The mold attaching member 16 of the upper mold 1 is connected to the mold body 4.
When the pressure receiving member 32 is pressed and moved downward by the eject pin 34 to lower the insert 11 relative to the mold mounting member 16 when the distance from the
Since the descending amount is smaller than the ascending amount (dimension S) of the mold mounting member 16, the insert 11 and the lens molded product 44 are formed.
Can be provided with the spectacle lens portion 44A. Therefore, even when the upper mold 1 is opened from the lower mold 2, the lens molded article 44 does not fall out of the cavity 3, and damage to the lens molded article 44 due to the fall can be prevented.

Further, in this embodiment, the insert 11
The holding members of the inserts 11 including the back insert 22, the hydraulic cylinder 19, and the pressure receiving member 32 are elastically urged upward by a spring 40 independently for each insert 11. Thus, even if there is a difference in spring force between the springs 40 of the inserts 11, the structure is not affected by the difference in the spring force. Since these holding members are provided separately for each, the holding members which are independent of each other can be pressed and moved downward by the eject pins 34 as predetermined, and the two eyeglass lens portions of the lens molded product 44 can be formed by the two inserts 11. 44A can protrude.

In the embodiment described above, the set compression allowance is set based on the opening amount formed between the mold main body 4 and the mold mounting member 16, but other molds may be used. . For example, using a mold having a structure in which a cavity core projecting into the cavity 3 is provided, a set compression allowance is set from the position of the cavity core, and the cavity core is compressed by projecting the cavity core into the cavity 3. Is also good.

Further, in the above-described embodiment, the opening size is set to 0.8 mm or less for a plus lens and larger than 0.8 mm for a minus lens. What is necessary is just to determine arbitrarily according to a characteristic etc. Further, in the above-described embodiment, when the molten resin is injected by about 90 to 95% at the time of molding the minus lens, the compression of the opening amount S (-) is started. Volume, resin type,
What is necessary is just to determine arbitrarily according to the characteristics of a lens.

Further, in the above-described embodiment, when the mold mounting member 16 of the upper mold 1 has risen from the mold main body 4 by the opening amount S, and when the mold main body 4 has opened the mold away from the lower mold 2. In this case, the eject pin 34 is moved downward in a two-stage manner, but the opening movement of the mold mounting member 16 by the mold clamping cylinder and the opening movement of the mold body 4 from the lower mold 2 are continuously performed. When this is performed, the downward movement of the eject pin 34 is continuously performed, thereby
May be made to protrude as it is by increasing the amount of lowering of the insert 11 with respect to.

[0046]

According to the injection compression molding method for spectacle lenses of the present invention, the set compression allowance at the time of molding a minus lens is set to be larger than the set compression allowance at the time of molding a plus lens. , And the plus lens and the minus lens can be formed with high accuracy and high quality regardless of the shape characteristics of the lens.

When the movable mold mounting member is retracted from the fixed mold, the holding member holding the insert provided on the movable mold main body is pressed and moved toward the fixed mold by an eject pin. Since the insert is advanced toward the fixed mold relative to the mold mounting member, when the lens molded product is ejected by the insert, the ejection can be performed while suppressing generation of compressed air. Therefore, the pressure of air compressed to high pressure does not act on the lens molded product,
The protrusion operation can be performed while securing the molding accuracy of a lens molded product molded with high precision. Therefore, the process from injection to release can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an injection mold used in an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a flowchart showing a molding procedure in the embodiment.

FIG. 4 is a view showing a state before injection and filling of molten resin during molding of a plus lens in the embodiment.

FIG. 5 is a diagram showing a state after compression of a molten resin during molding of a plus lens in the embodiment.

FIG. 6 is a view showing a state before injection and filling of a molten resin during molding of a minus lens in the embodiment.

FIG. 7 is a diagram showing a state after compression of a molten resin during molding of a minus lens in the embodiment.

FIG. 8 is a view showing a state in which the upper mold mounting member is raised from the mold main body by a slight opening amount and the upper mold insert is relatively moved downward with respect to the mold mounting member by an eject pin in the embodiment. FIG.

FIG. 9 is a view showing a state where the upper mold and the lower mold are opened from the state of FIG. 8;

[Explanation of symbols]

Reference Signs List 1 upper mold (movable mold) 2 lower mold (fixed mold) 3 cavity 4 mold body 5, 9 insert guide 10, 11 insert 16 mold mounting member 19, 22, 32 Hydraulic cylinder constituting holding member,
Back insert and pressure receiving member 34, 38 Eject pin 40 Spring (elastic member) 44 Lens molded product 58 Sprue 59 Runner S Maximum opening (maximum compression allowance) S (+) Plus opening at lens molding (set compression allowance) ) S (-) Dimensional opening at minus lens molding (set compression allowance)

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[Procedure amendment]

[Submission date] May 10, 2002 (2002.5.1)
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Patent application title: Injection compression molding of spectacle lenses

[Claims]

3. A movable mold that opens and closes with respect to a fixed mold includes a mold mounting member, and a mold main body movably mounted on the mold mounting member toward the fixed mold. Inside the main body, there is provided an insert which is movably fitted into an insert guide to form a lens cavity, and a holding member for holding the insert is an elastic member which is always elastic in a direction opposite to the fixed type. Using a molding die pressed against the die mounting member
Mold a minus lens whose center thickness is thinner than the periphery
A molding method, wherein the mold mounting member is advanced to the fixed mold side to clamp the mold while leaving a preset compression allowance in the lens cavity, and then molten resin is injected into the lens cavity. Filling, compressing the set compression allowance by advancing the mold mounting member to the fixed mold side at least after the time before the completion of the injection of the molten resin, and thereafter, retreats the mold mounting member, from the fixed mold. After the movable mold is opened, in an injection compression molding method of a spectacle lens in which the holding member is pressed and moved toward the fixed mold side by an eject pin inserted into the mold mounting member and a lens molded product is protruded by the insert. , Set the compression allowance to different values depending on the lens power
And, compression of the set compression margin open before completion of injection of the molten resin
And, after the injection of the molten resin is completed, the lens cavity and the like.
And a sprue for supplying molten resin into the cavity,
The runner is a closed space, and when the mold mounting member is retracted, the eject pin is used to press and move the holding member to the fixed mold side, whereby the insert is relatively moved with respect to the mold mounting member. Wherein the movable mold is opened from the fixed mold, the holding member is pressed and moved by the eject pin, and a lens molded product is protruded by the insert. Law.

4. The injection compression molding method for a spectacle lens according to claim 3 , wherein the setting of the set compression allowance at the time of molding the minus lens is performed from the initial position where the compression allowance in the lens cavity is maximum. The injection compression molding method for spectacle lenses, wherein the mold mounting member is advanced to the fixed mold side to a position where a margin is left and the mold is clamped.

5. The injection compression molding method of a spectacle lens according to claim 3 or claim 4, when advancing the insert relatively the stationary mold side with respect to the fitment member, the said insert An injection compression molding method for a spectacle lens, characterized in that the mold mounting member is advanced by less than a retreat amount at the time of retreat, and a gap is provided between the insert and the lens molded product.

6. The injection compression molding method for an eyeglass lens according to claim 5 , wherein a gap between the insert and the lens molded product is 1 to 4 mm.

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injection compression molding of a spectacle lens for obtaining a spectacle lens by injection compression molding of a thermoplastic resin. More particularly, to an injection compression molding method of a spectacle lens may be molded Ma Inasurenzu with high accuracy and high quality.

[0002]

BACKGROUND ART As a molding method for obtaining a lens from a thermoplastic resin, an injection compression molding method is known (for example, JP-A-2-26723 and JP-B-6-9826). For spectacle lenses, lens power + 4.00D-
A lens having a lens power range of about 8.00D is preferably used in this molding method. The injection compression molding method corrects the shrinkage of the molten resin, clamps the mold while leaving a compression allowance in the lens cavity, and obtains uniform and high shape accuracy. Is a molding method in which a molten resin is injected and filled, and then the compression margin is compressed to obtain a lens.

[0003]

By the way, the lens is
If the curvature is different between the front side and the rear side of the lens, the lens thickness causes a thickness difference, and assuming that there is a thickness difference, a plus lens whose center part is thicker than the peripheral part, and a center part whose thickness is the peripheral part There are two types: a thinner minus lens. The lens thickness differs depending on the design of the optical lens. For example, in the case of an aspherical lens having a refractive index of about 1.50, the center thickness is 4.2 mm at + 2.00D, the peripheral thickness is 1.0 mm, and the center thickness is -4.00D at 1 mm. A design value of about 0.4 mm and a peripheral thickness of about 7.9 mm can be set. However, when compression molding is performed on these lenses under the same conditions, the following problems occur due to the difference in the shape characteristics.

In molding a minus lens, the central portion of the lens is thinner than the peripheral portion, so that the flow resistance is large at the central portion of the cavity. Therefore, the molten resin injected into the cavity is difficult to flow in the central portion of the cavity, and diverges from the peripheral portion to the central portion, so that there is a problem that many weld marks are easily generated in the central portion.
You.

An object of the present invention is to provide an injection compression molding method of a spectacle lens can be molded to Ma Inasurenzu in and high quality precision. Another object of the present invention is to provide an injection compression molding method of a spectacle lens can be molded efficiently between Inasurenzu from the injection to the release.

[0006]

According to the injection compression molding method for a spectacle lens according to the present invention, the thickness of the central portion is smaller than that of the peripheral portion.
A molding method Inasurenzu, the mold was clamping leaving setting compression margin set in advance in the O-flop Pharmaceutical cavity lens formed from the insert space, then injecting a molten resin into the lens cavity In the injection compression molding method of a meniscus-shaped spectacle lens for filling and compressing the set compression margin at least after completion of the injection of the molten resin, the set compression margin varies depending on the lens power.
Value before the injection of the molten resin is completed.
Starts the compression allowance and injects the molten resin
After completion, the lens cavity and this cavity
Closed space with sprue and runner for supplying molten resin inside
Characterized by a.

[0007] In such a molding method, increase the set compression margin at minus lens molding, that is, larger than the set compression margin during positive lens molding Then, with a wider cavity region can be secured, the molten resin in the cavity In molding the minus lens, the molten resin that has reached the inside of the cavity flows through the central portion of the cavity into the peripheral portion without shunting during molding of the minus lens.
Therefore, it is possible to prevent the occurrence of a weld mark at the center portion, and to maintain a sufficient pressing force with the strength lens, thereby improving the transferability with the mold. Incidentally, the setting compression margin at minus lens molding, larger than the set compression margin during positive lens molding result, the flow of the molten resin while leaving a large unfilled portion in the lens cavity in the injection filling completion of the molten resin This causes a problem that the filling history of the resin called a flow mark is likely to occur in the critical part between the filled part and the unfilled part in the molded lens after the pressing step. For this point, the injection compression molding method of a spectacle lens according to the present invention, when Ma Inasurenzu molding, it is so arranged to initiate compression of the set compression margin before completion of injection of the molten resin, the more the resin Fluidity and transferability can be improved. That is, at the time of molding the minus lens, the compression of the set compression margin is started before the injection of the molten resin is completed, and the volume of the lens cavity is reduced, so that the flowability of the molten resin is increased, and the injection filling of the molten resin is completed. Since a large unfilled portion is less likely to remain in the lens cavity at the time, the occurrence of a flow mark can be prevented. At this time, when the injection of the molten resin is completed during molding of the minus lens, the lens cavity including the sprue and the runner is immediately made into a closed space . Therefore , even if the molten resin in the lens cavity is pressurized by compression, the molten resin is sprued. Since there is no back flow out of the lens cavity including the runner, excellent mold transferability,
It is possible to obtain a high-precision, high-quality lens having no striae or ejection history. Particularly, it is useful for molding a strong lens.

[0008] In the above injection compression molding method, it is necessary to greatly set configuration compression margin at minus lens molding. At that time, the setting of the compression allowance at the time of molding the minus lens is set in the same way as the setting of the compression allowance at the time of molding the plus lens, from the initial position where the compression allowance in the lens cavity is the maximum to the position where the compression allowance disappears. After the mold was clamped, if the mold was set by opening the mold by the set compression allowance, the distance to open the mold by the set compression allowance was long,
The problem is that the efficiency is poor in terms of time.

[0009] By the way, set compression margin in the case of a positive lens molding is not large, 0.8mm or less under, for example, +
For 1.00D to + 3.00D lenses, 0.1mm to
0.2 mm is sufficient. On the other hand, if the negative lens molding varies depending frequency and performance after molding, set compression margin is preferably 5 mm to 15 mm. Further, in the mold clamping control of the mold, it is an advanced control to control the upward movement from the maximum compression position (lowest lower limit position) at a pitch of 0.1 mm in a vertical molding machine due to the structure of the molding machine. Requires a long time for control. For example, it may take 10 seconds or more for a movement of 5 mm. On the other hand, it is easy to move the mold from above to below, and even within 15 mm, it is within 1 second.

Accordingly, an injection compression molding method of a spectacle lens according to the present invention, the setting of the setting compression margin when Ma Inasurenzu molding, leaving the set compression margin from compression allowance is the maximum of the initial position in the lens cavity The position is set by clamping the mold to the position shown in FIG.

In this way, the set compression allowance at the time of molding the minus lens can be set by clamping the mold from the initial position where the compression allowance in the lens cavity is maximum to the position where the set compression allowance is left. from, that is, because there is no operation of opening the mold long distance setting compression allowance of, Ru can be done quickly and accurately set the setting compression margin.

Further, in the injection compression molding method for an eyeglass lens according to the present invention, a movable die which opens and closes with respect to a fixed die is mounted on a die mounting member and movably mounted on the die mounting member toward the fixed die. And an insert for movably fitted into an insert guide to form a lens cavity is provided inside the mold body, and a holding member for holding the insert is elastic. The member is always elastically urged in a direction opposite to the fixed mold and is formed by using a molding die abutted on the mold mounting member.
Molds a minus lens with a thinner central part than the peripheral part.
A molding method, wherein the mold mounting member is advanced to the fixed mold side to clamp the mold while leaving a preset compression allowance in the lens cavity, and then molten resin is injected into the lens cavity. Filling, compressing the set compression allowance by advancing the mold mounting member to the fixed mold side at least after the time before the completion of the injection of the molten resin, and thereafter, retreats the mold mounting member, from the fixed mold. After the movable mold is opened, in an injection compression molding method of a spectacle lens in which the holding member is pressed and moved toward the fixed mold side by an eject pin inserted into the mold mounting member and a lens molded product is protruded by the insert. , The set compression allowance, the lens power
Before injection of the molten resin is completed.
Start the compression of the set compression allowance at
After the resin injection is completed, the lens cavity and this
Sprues and runners to supply molten resin into the cavity
The insert is advanced toward the fixed mold side relative to the mold mounting member by moving the holding member toward the fixed mold side with the eject pin when the mold mounting member retreats as a closed closed space. Thereafter, the movable mold is opened from the fixed mold, the holding member is pressed and moved by the eject pin, and the lens molded product is protruded by the insert.

According to this molding method, to prevent the occurrence of weld mark in the central portion, in addition to the effect of forming the Ma Inasurenzu in and high quality precision, the following effects can be expected. That is, when the movable mold mounting member is retracted, the holding member is pressed and moved to the fixed mold side by the eject pin, whereby the insert advances to the fixed mold side relative to the movable mold mounting member. Therefore, a gap having the same size as the retreat amount of the mold mounting member does not occur between the lens molded product and the insert in the cavity.
The generation of excessive compressed air can be suppressed, and the pressure of the compressed air acting on the lens molded product can be prevented. Therefore, there is no mold release defect such as breakage of a part formed by the sprue or runner or deviation from the mold at the time of mold release, and a lens molded product having high molding accuracy can be obtained.

Here, when the movable die mounting member is retracted, the holding member is pressed and moved by the eject pin to advance the insert toward the fixed die relative to the movable die mounting member. The amount of advance may be the same as the amount of retreat (slight opening) of the mold mounting member, and may be large, but smaller is more preferable.

If the amount of advance is smaller than the amount of retreat of the mold mounting member, a gap can be provided between the insert and the lens molded product. Therefore, even when the movable mold is opened from the fixed mold, the lens molded product is removed from the cavity. Without falling off,
Prevents damage to lens molded products due to falling off. In particular, the gap between the insert and the lens molded product is preferably 1 to 4 mm.
If the gap is less than 1 mm, there is a risk that the lens molded product will fall off. If the gap is more than 4 mm, the effect of suppressing the generation of excessive compressed air is low.

That is, when the fastening force is released after the mold clamping, the compression margin is set to a large value, so that the retraction largely and abruptly retreats. In particular, the molding environment (mainly the temperature) on the convex side of the lens greatly changes. Therefore, a phenomenon occurs in which a release force is strongly applied to a part of the lens surface to cause a release failure, or a sprue or a runner portion is broken. Therefore, by setting the above clearance, by to have an intermediate ejection function, Ru der those partial release acting on a part of the molding part prevent such excessive.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a spectacle lens according to the present embodiment (a meniscus-shaped spectacle lens;
FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, showing a mold for injection compression molding used in an injection compression molding method (multifocal, progressive multifocal). The material of the spectacle lens molded here is a thermoplastic resin such as PMMA (polymethyl methacrylate) and PC (polycarbonate). In the present embodiment, low-output ejection is used to prevent striae and optical distortion.

In the injection compression molding mold, as shown in FIG. 1, two spectacle lens cavities 3 are provided between an upper mold 1 and a lower mold 2 which are vertically divided on a parting line PL. This is a mold for taking two formed lenses.

The upper die 1 is a movable die that vertically closes and opens the lower die 2 that is a fixed die.
And a mold body 4 movably attached to the mold attaching member 16 toward the lower mold 2. Mold mounting member 16
Consists of an upper member 16A and a lower member 16B. Mold body 4
Consists of an insert guide 5 and template plates 6,7. The lower mold 2 includes a mold body 8 including an insert guide 9 and a mold plate 10, and a mold attachment member 15 to which the mold body 8 is attached. Inserts 11 and 12 forming the cavity 3 are accommodated inside the insert guides 5 and 9 so as to be slidable in a direction perpendicular to the parting line PL.

The mold body 4 of the upper mold 1 is connected to the mold mounting member 16 by bolts 17 shown in FIG. 2, and between the mold body 4 and the mold mounting member 16 is an outer periphery of the bolt 17. The inserted disc spring 17A is interposed. The mold mounting member 16 is moved up and down by a mold clamping cylinder (not shown). A gap S is provided between the mold body 4 and the mold mounting member 16, and the mold body 4 and the mold mounting member 16 are opened and closed up and down by the gap S while being guided by the guide pins 18. It is supposed to. A gap opening cylinder (not shown) is disposed below the mold mounting member 15, and the gap S is formed by the mold opening member 16 being pushed up against the clamping force of the mold clamping cylinder by the opening cylinder. It is supposed to be.

The mold mounting member 16 is provided with a downward hydraulic cylinder 19 so as to be vertically movable. Piston rod 21 connected to piston 20 of hydraulic cylinder 19
Is provided with a T-shaped clamp member 23 at the end thereof, penetrating through the inside of the back insert 22 fixed to the lower surface of the cylinder 19. The T-shaped clamp member 23 includes the insert 1
1 is removably engaged with a T-shaped groove 24 formed on the upper end surface. The mold mounting member 15 is provided with an upward hydraulic cylinder 26. The piston rod 28 connected to the piston 27 of the hydraulic cylinder 26 penetrates through the inside of the mold mounting member 15 and has a T-shaped clamp member 29 at its tip. The T-shaped clamp member 29 is connected to the insert 1.
2 is engaged with a T-shaped groove 30 formed on the lower end surface so as to be freely detachable.

A pressure receiving member 32 is fixed to the upper end of the hydraulic cylinder 19. When the pressure receiving member 32 is pushed down by the eject pin 34 inserted from the hole 33 formed in the mold attachment member 16, the hydraulic cylinder 19, the back insert 22 and the insert 11 are also pushed down, and the lens molded product molded in the cavity 3 is formed. The upper mold 1 and the lower mold 2 are protruded when the mold is divided. Here, a holding member that holds the insert 11 is configured by the back insert 22, the hydraulic cylinder 19, and the pressure receiving member 32. An eject bar 35 is disposed at the center of the mold mounting member 16 of the upper mold 1 so as to be vertically movable. A pressure receiving member 36 is fixed to an upper end of the eject bar 35. When the pressure receiving member 36 is pushed down by the eject pin 38 inserted from the hole 37 formed in the mold attaching member 16, the eject bar 35 is pushed down.

The spring force of the spring 40 wound around the outer circumference of the eject return pin 39 acts on the pressure receiving member 32 upward. Although not shown, the spring force of the spring wound around the outer periphery of the eject return pin also acts on the pressure receiving member 36 in an upward direction. Therefore, when the eject pins 34, 38 rise, the pressure receiving members 32, 36
Has also risen and returned to its former position. here,
The holding member constituted by the back insert 22, the hydraulic cylinder 19 and the pressure receiving member 32 is always elastically urged in a direction opposite to the lower mold 2 by a spring 40 which is an elastic member, and is in contact with the mold mounting member 16. .

Next, the operation of this embodiment will be described. First, the inserts 11 and 12 are exchanged according to the type of lens to be molded. Inserts 11 and 12
In the replacement, the upper mold 1 including the mold attaching member 16 is raised and the mold is divided from the lower mold 2. Further, the piston rod 21 of the hydraulic cylinder 19 is lowered, and the piston rod 28 of the hydraulic cylinder 26 is raised.
The character clamp members 23, 29 are projected from the insert guides 5, 9.

New mold bodies 4 and 8 of upper mold 1 and lower mold 2
The inserts 11 and 12 mounted on the insert are horizontally transferred while being held by a robot arm (not shown), and the T-shaped grooves 24 and 30 of the inserts 11 and 12 are inserted into the T-shaped clamp member 2.
3, 29 are engaged. Thereafter, the piston 11 is raised by raising the piston rod 21 of the hydraulic cylinder 19, and the piston 12 is lowered by lowering the piston rod 28 of the hydraulic cylinder 26. This allows
Inserts 11 and 12 are fitted to insert guides 5 and 9. In this manner, in the case of molding a plus lens (a lens having a central portion thicker than the peripheral portion), the inserts 11A and 12A shown in FIGS. 6 and 7, inserts 11B and 12 shown in FIGS.
Exchange each for B.

Now, in molding the lens, the operation proceeds according to the flowchart shown in FIG. First, FIG.
Then, the mold is closed as shown in FIG. That is, the upper mold 1 is lowered by the mold clamping cylinder, and the mold plate 6 of the upper mold 1 is brought into contact with the mold plate 10 of the lower mold 2 and the mold is closed so that the disc spring 17A is not compressed. In this state, the gap S is set to the maximum opening amount (about 15 mm), that is, the compression allowance in the cavity 3 is set to the maximum initial position. Next, an opening amount (set compression allowance) is set. At this time, in the molding of the plus lens, an opening amount S (+) of 0.8 mm or less is set.
In molding of a minus lens, an opening amount S (−) larger than 0.8 mm is set. That is, the set compression allowance at the time of molding the minus lens is set to be larger than the set compression allowance at the time of molding the plus lens.

Here, in the case of molding a plus lens, that is, when the opening amount S (+) of 0.8 mm or less is set, as shown in FIG. Is further lowered (at this time, the disc spring 17A is compressed), and the gap S is completely eliminated. Then, the mold mounting member 16 is opened by the slightly open cylinder against the closing force of the closing cylinder. Raise by S (+), and set the opening amount S (+). On the other hand, in the case of molding a minus lens, that is, when the opening amount S (−) larger than 0.8 mm is set, as shown in FIG. It is lowered to the position where the amount S (-) remains (at this time, the disc spring 17A is compressed), and stopped at that position to set the slightly open amount S (-).

Next, the molten resin is injected and filled. For this, the molten resin is injected from the nozzle of the injection molding machine connected to the sprue bush 57 and the sprue 58 and the runner 5
9 to fill the cavity 3. At this time, in the case of molding a plus lens (FIG. 4), the thickness of the central portion of the cavity 3 (the central portion of the lens) is large, so that the molten resin that has reached the inside of the cavity 3 is Through the center) to the periphery. On the other hand, in the case of molding a minus lens, since the opening S (−) larger than 0.8 mm is set, that is, the thickness of the central portion of the cavity 3 is set large, Reaches the peripheral portion through the central portion of the cavity 3 without shunting. Therefore, in any case, the weld mark at the central portion is suppressed.

Next, in the case of molding a plus lens (FIG. 4)
After the injection of the molten resin is completed, the space including the cavity 3, the runner 59, and the sprue 58 is closed to form a closed space, and then pressurized (compressed). That is, FIG.
As shown in (2), the mold mounting member 16 is lowered by the opening S (+) by the mold clamping cylinder. On the other hand, in the case of molding a minus lens (FIG. 6), pressurization (compression) is started before the injection of the molten resin is completed. Specifically, when about 90 to 95% of the molten resin to be injected has been injected, pressurization is started by the mold clamping cylinder, and as shown in FIG.
6 is lowered by the opening S (-). At this time, the nozzle is closed immediately after the injection of the molten resin is completed, and the space including the cavity 3, the runner 59, and the sprue 58 is made a closed space.

Next, after forming a plus lens or a minus lens in this way, these lenses are ejected. To this end, the mold mounting member 16 of the upper mold 1 is raised by the mold clamping cylinder, that is, raised from the lower mold 2,
An opening amount S is opened between the mold body 4 and the mold body 4. At this time, the eject pin 34 is lowered by the eject cylinder, and the pressure receiving member 32 is moved downward by the eject pin 34 with respect to the mold mounting member 16. This pressing movement amount is smaller than the opening amount S, and the opening amount S is, for example, 15
mm, the amount of pressing movement is 13 mm. In other words, when the mold mounting member 16 is raised, the insert 11
Is lowered toward the lower die 2 relative to the die mounting member 16.

As a result, when the mold mounting member 16 originally rises by the opening amount S, the rising amount of the insert 11 which rises by the same amount can be suppressed to a small value.
For example, in minus lens molding, as shown in FIG.
The insert 11 has a slight gap A from the spectacle lens portion 44A of the lens molded product 44 molded in the cavity 3,
If the opening or pressing movement is the same as the numerical value, 2
It is separated by the gap A of mm.

Thereafter, as shown in FIG. 9, the mold mounting member 16 and the mold body 4 of the upper mold 1 are raised by the mold clamping cylinder, and the upper mold 1 is moved upward.
Is opened from the parting line PL with respect to the lower mold 2. Thereafter, a part of the lens molded product 44 exposed from the lower surface of the upper mold 1 is gripped by the gripping device, and the eject pin 3
4 and 38 are lowered by the respective eject cylinders, whereby the pressure receiving members 32 and 36 are pressed and moved, and the lens molded product 44 is protruded by the insert 11 and the eject bar 35. At the time of this protrusion, the lens molded product 4
Since the insert 11 is only apart from the spectacle lens portion 44A by a small gap A, the air entering the gap A is not compressed to a large pressure by the insert 11, and the compressed air is not compressed. The lens molded product 44 can be protruded from the upper mold 1 without applying a large pressure to the spectacle lens portion 44A.

That is, when the mold attaching member 16 of the upper mold 1 rises from the mold main body 4 by the opening S, the ejecting pin 34 does not press and move the pressure receiving member 32 downward. When the insert 11 is not lowered relatively, the spectacle lens portion 44A of the lens molded product 44
A gap having the same size as the opening size S is formed between the insert 11 and the insert 11, and when the insert 11 projects the spectacle lens portion 44A, the air in this gap is greatly compressed and excessive high-pressure air is generated. Although this acts on the spectacle lens portion 44A, which is a precision molded portion, in the embodiment according to the present invention, a slight gap A can be formed between the spectacle lens portion 44A and the insert 11, so that the insert 11 When the spectacle lens portion 44A of the lens molded product 44 is protruded, it is possible to suppress the generation of excessive compressed air and perform the protruding, and to break the mold at the part formed by the sprue 58 or the runner 59 or to release the mold. A highly accurate molding state of the spectacle lens portion 44A can be ensured without a mold release defect such as displacement.

According to the present embodiment, the opening amount S (-) at the time of molding a minus lens is changed to the opening amount S (at the time of molding a plus lens).
Since the value is set to be larger than (+), a wider cavity area can be secured, and the fluidity of the resin in the cavity can be improved. Therefore, at the time of molding the minus lens, the molten resin that has reached the inside of the cavity 3 flows into the peripheral portion through the central portion of the cavity 3 without shunting, so that the occurrence of weld marks at the central portion can be prevented. Therefore, the plus lens and the minus lens can be formed with high precision and high quality regardless of the shape characteristics of the lens.

At this time, it is necessary to set the opening amount S (-) at the time of forming the minus lens larger than the opening amount S (+) at the time of forming the plus lens. Since the opening amount S (-) is set by lowering the mold mounting member 16 of the upper die 1 to the position where the opening amount S (-) is left, the opening amount S (-) is set. Can be performed quickly and with high accuracy. On the other hand, the opening amount S (+) at the time of molding a plus lens is the opening amount S (-) at the time of molding a minus lens.
Therefore, in this case, after lowering the mold mounting member 16 of the upper mold 1 from the initial position where the opening amount S is the maximum to the position where the opening amount S disappears, the opening amount S (+) Since the opening amount S (+) is set by opening, the opening amount S (+) can be set quickly and accurately.

Also, at the time of molding the minus lens, since the compression of the opening size S (+) is started before the completion of the injection of the molten resin, the volume of the cavity 3 is reduced before the injection of the molten resin is completed. Therefore, a large unfilled portion is unlikely to remain in the cavity 3 at the time of completion of the injection and filling of the molten resin, so that the occurrence of a flow mark can be prevented. That is,
If the opening size S (+) is set to be large, the flow of the molten resin is stopped while leaving a large unfilled portion in the cavity at the time of completion of the injection filling of the molten resin, and the flow of the filled portion and the unfilled portion is stopped. Although there is a problem that a filling history of a resin called a flow mark is likely to occur in the critical part, the occurrence of the flow mark can be prevented by adopting the present embodiment.

When the mold mounting member 16 of the upper mold 1 is lifted from the lower mold 2, the holding member holding the insert 11 provided on the mold body 4 of the upper mold 1 is ejected by the eject pin 34. 2 to lower the insert 11 toward the lower mold 2 relative to the mold mounting member 16, so that when the lens molded product 44 is protruded by the insert 11, the generation of compressed air is suppressed. Since the protrusion can be performed, and the pressure of the high-pressure compressed air does not act on the lens molded product 44, the protrusion operation can be performed while securing the molding accuracy of the lens molded product 44 formed with high precision.

The mold attaching member 16 of the upper mold 1 is connected to the mold body 4.
When the pressure receiving member 32 is pressed and moved downward by the eject pin 34 to lower the insert 11 relative to the mold mounting member 16 when the distance from the
Since the descending amount is smaller than the ascending amount (dimension S) of the mold mounting member 16, the insert 11 and the lens molded product 44 are formed.
Can be provided with the spectacle lens portion 44A. Therefore, even when the upper mold 1 is opened from the lower mold 2, the lens molded article 44 does not fall out of the cavity 3, and damage to the lens molded article 44 due to the fall can be prevented.

Further, in this embodiment, the insert 11
The holding members of the inserts 11 including the back insert 22, the hydraulic cylinder 19, and the pressure receiving member 32 are elastically urged upward by a spring 40 independently for each insert 11. Thus, even if there is a difference in spring force between the springs 40 of the inserts 11, the structure is not affected by the difference in the spring force. Since these holding members are provided separately for each, the holding members which are independent of each other can be pressed and moved downward by the eject pins 34 as predetermined, and the two eyeglass lens portions of the lens molded product 44 can be formed by the two inserts 11. 44A can protrude.

In the embodiment described above, the set compression allowance is set based on the opening amount formed between the mold body 4 and the mold mounting member 16, but other molds may be used. . For example, using a mold having a structure in which a cavity core projecting into the cavity 3 is provided, a set compression allowance is set from the position of the cavity core, and the cavity core is compressed by projecting the cavity core into the cavity 3. Is also good.

In the above-described embodiment, the size of the opening is set to 0.8 mm or less for the plus lens and larger than 0.8 mm for the minus lens. What is necessary is just to determine arbitrarily according to a characteristic etc. Further, in the above-described embodiment, when the molten resin is injected by about 90 to 95% at the time of molding the minus lens, the compression of the opening amount S (-) is started. Volume, resin type,
What is necessary is just to determine arbitrarily according to the characteristics of a lens.

Further, in the above-described embodiment, when the mold mounting member 16 of the upper mold 1 has risen from the mold body 4 by the opening S, and when the mold body 4 has opened the mold away from the lower mold 2. In this case, the eject pin 34 is moved downward in a two-stage manner. However, the opening movement of the mold mounting member 16 by the mold clamping cylinder and the opening movement of the mold body 4 from the lower mold 2 are continuously performed. When the ejection is performed, the downward movement of the eject pin 34 is continuously performed.
May be made to protrude as it is by increasing the descending amount of the insert 11 with respect to.

[0043]

According to an injection compression molding method of a spectacle lens of the present invention, can be molded Ma Inasurenzu in and high quality precision.

When the movable mold mounting member is retracted from the fixed mold, the holding member holding the insert provided on the movable mold main body is pressed and moved toward the fixed mold by an eject pin. Since the insert is advanced toward the fixed mold relative to the mold mounting member, when the lens molded product is ejected by the insert, the ejection can be performed while suppressing generation of compressed air. Therefore, the pressure of air compressed to high pressure does not act on the lens molded product,
The protrusion operation can be performed while securing the molding accuracy of a lens molded product molded with high precision. Therefore, the process from injection to release can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an injection mold used in an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a flowchart showing a molding procedure in the embodiment.

FIG. 4 is a view showing a state before injection and filling of molten resin during molding of a plus lens in the embodiment.

FIG. 5 is a diagram showing a state after compression of a molten resin during molding of a plus lens in the embodiment.

FIG. 6 is a view showing a state before injection and filling of a molten resin during molding of a minus lens in the embodiment.

FIG. 7 is a diagram showing a state after compression of a molten resin during molding of a minus lens in the embodiment.

FIG. 8 is a view showing a state in which the upper mold mounting member is raised from the mold main body by a slight opening amount and the upper mold insert is relatively moved downward with respect to the mold mounting member by an eject pin in the embodiment. FIG.

FIG. 9 is a view showing a state where the upper mold and the lower mold are opened from the state of FIG. 8;

[Description of Signs] 1 Upper mold (movable mold) 2 Lower mold (fixed mold) 3 Cavity 4 Mold main body 5, 9 Insert guide 10, 11 Insert 16 Mold mounting member 19, 22, 32 Hydraulic cylinder constituting holding member,
Back insert and pressure receiving member 34, 38 Eject pin 40 Spring (elastic member) 44 Lens molded product 58 Sprue 59 Runner S Maximum opening (maximum compression allowance) S (+) Plus opening at lens molding (set compression allowance) ) S (-) Dimensional opening at minus lens molding (set compression allowance)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Asami 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo F-term in Hoya Corporation (reference) 4F206 AH74 AM36 AR075 JA03 JL02 JM02 JM04 JM05 JN33 JN41 JP17 JQ02 JQ81

Claims (10)

[Claims] 1. A mold is clamped while leaving a preset compression allowance in a lens cavity space formed from a replaceable optical insert, and then a molten resin is injected and filled into the lens cavity. In the injection compression molding method of a meniscus-shaped spectacle lens that compresses the set compression allowance at least after the time before the completion of the injection of the molten resin, the set compression allowance at the time of molding a minus lens having a central part thickness smaller than the peripheral part is An injection compression molding method for a spectacle lens, characterized in that the thickness of the central portion is larger than the peripheral portion, and is larger than a set compression allowance in molding a plus lens. 2. The injection compression molding method for an eyeglass lens according to claim 1, wherein the setting of the compression allowance at the time of molding the plus lens is such that the compression allowance in the lens cavity is set from an initial position where the compression allowance is maximum. After the mold is clamped to the position where it disappears, the mold is further set by opening the mold by the set compression allowance.The setting of the set compression allowance at the time of molding the minus lens is performed by setting the compression allowance in the lens cavity. An injection compression molding method for a spectacle lens, wherein the setting is performed by clamping the mold from a maximum initial position to a position where the set compression margin is left. 3. The injection compression molding method for an eyeglass lens according to claim 1, wherein, at the time of molding the minus lens, compression of the set compression margin is started before injection of the molten resin is completed. Injection compression molding of spectacle lenses. 4. The injection compression molding method of a spectacle lens according to claim 3, wherein after the injection of the molten resin is completed, the lens cavity and a sprue and a runner for supplying the molten resin into the cavity are formed in a closed space. Injection molding of spectacle lenses. 5. The injection compression molding method for a spectacle lens according to claim 1, wherein, at the time of molding the positive lens, compression of the set compression margin is started after injection of the molten resin is completed. Injection compression molding of spectacle lenses. 6. The injection compression molding method for an eyeglass lens according to claim 5, wherein before starting the compression of the set compression allowance, the lens cavity and a sprue and a runner for supplying a molten resin into the cavity are provided. An injection compression molding method for a spectacle lens, characterized in that it is a closed space. 7. A movable mold that opens and closes with respect to a fixed mold includes a mold attachment member, and a mold body movably attached to the mold attachment member toward the fixed mold. Inside the main body, there is provided an insert which is movably fitted into an insert guide to form a lens cavity, and a holding member for holding the insert is an elastic member which is always elastic in a direction opposite to the fixed type. The mold mounting member is pressed against the mold mounting member, and the mold mounting member is moved forward to the fixed mold side to clamp the mold leaving a preset compression allowance in the lens cavity. The molten resin is injected and filled therein, and at least after the time before the completion of the injection of the molten resin, the set compression allowance is compressed by advancing the mold mounting member to the fixed mold side, and thereafter, the mold is cooled. After the attached member is retracted and the movable mold is opened from the fixed mold, the holding member is pressed and moved toward the fixed mold by an eject pin inserted into the mold mounting member, and the lens molded product is formed by the insert. In the injection compression molding method for spectacle lenses that protrude, the set compression allowance at the time of molding a minus lens whose central part is thinner than the peripheral part is larger than the set compression allowance at the time of plus lens molding whose central part is thicker than the peripheral part. At the same time, by moving the holding member toward the fixed mold side with the eject pin when the mold mounting member is retracted, the insert is advanced toward the fixed mold side relative to the mold mounting member, Thereafter, the movable mold is opened from the fixed mold, the holding member is pressed and moved by the eject pin, and the lens molded product is pushed by the insert. Injection compression molding method of a spectacle lens, characterized in Succoth. 8. The injection compression molding method for an eyeglass lens according to claim 7, wherein the setting of the compression allowance at the time of molding the plus lens is such that the compression allowance in the lens cavity is set from an initial position where the compression allowance is maximum. The mold mounting member is advanced to the fixed mold side to a position where it disappears, the mold is clamped, and the mold mounting member is set by retreating by the set compression allowance. Eyeglasses wherein the mold allowance is set by advancing the mold mounting member to the fixed mold side and clamping the mold from the initial position where the compression allowance in the lens cavity is maximum to the position where the set compression allowance is left. Injection compression molding of lenses. 9. The injection compression molding method for an eyeglass lens according to claim 7, wherein the insert is moved toward the fixed mold relative to the mold mounting member. An injection compression molding method for a spectacle lens, characterized in that the mold mounting member is advanced by less than a retreat amount at the time of retreat, and a gap is provided between the insert and the lens molded product. 10. The injection compression molding method for an eyeglass lens according to claim 9, wherein a gap between the insert and the lens molded product is 1 to 4 mm.