JPH0459314A - Mold releasing method of plastic lens and its device - Google Patents

Abstract

PURPOSE:To constitute the above method so that a flaw and crack are not generated, by a method wherein heating is performed by applying far infrared rays in a wave range where an absorption factor of a plastic lens becomes higher than that of a mold to the mold, and the plastic lens is released from the mold by a difference in thermal expansion. CONSTITUTION:After a removal of a gasket 3 and clip 5 from an assembled article 6 of lens molds, the assembled articles 6 of the lens molds constituted of glass molds 1, 2 having the coefficient of linear expansion of 9.5X10<-6> and plastic lens L having the coefficient of linear expansion of 14X10<-5> are put on a rack 25 at intervals of 30mm in a longitudinal direction and conveyed within a main body in the direction of an arrow view at a conveying speed of 0.3m/min. In other words, since it becomes that the mold is hard to absorb far infrared rays and the plastic lens is easy to absorb the far infrared rays, only the plastic lens is heated selectively. Furthermore, the outsides of the molds 1, 2 are cooled by the open air introduced into a heating chamber H by a ventilation fan 24. Therefore, mold release of the plastic lens becomes an easily-acceleratable state in the fitting chamber H.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for easily releasing from a mold a plastic lens that has been polymerized in a mold and is integrally attached to the mold. and improvements to its equipment.

[Prior Art] Conventionally, as shown in FIG. 3, the polymerization type of plastic lens consists of two glass molds 1.2 each having an uneven curved surface on both sides, and a protrusion 3a having a width S inside. It is inserted into a plastic gasket 3 having a mold and fixed with clips 5 from both sides of the mold while maintaining a gap S, and then a molten resin of a thermosetting monomer is poured into the gap S from the injection port 4, The mold 1.2, the gasket 3, and the entire molten resin were heated to form a polymerization mold.

The thus obtained plastic lens L after curing between the molds 1 and 2 has a shape suitable for a lens since both surfaces thereof are molded along the uneven curved surfaces of the molds J and 2. However, due to the polymerization process, mold 1. is formed on both sides of the plastic lens L.
2 are tightly stuck together and become one body (hereinafter, such a mold 1.2 and plastic lens L integrated together will be referred to as a lens mold assembly 6), and the gasket 3 is removed. There was also a problem that the plastic lens L could not be easily removed from the mold.

The conventional plastic lens mold release method and device used for such a lens mold assembly 6 are: A method of fixing it in a vise and inserting the tip of the cutter into the interface between the plastic lens L and the mold 1.2 to pry them apart. ■ A rack on which multiple lens mold assemblies 6 are placed is heated to about 80°C. The mold was released using the so-called heat shock method, in which the mold was immersed in a hot water tank filled with warm water, and then immediately cooled by spraying water or air.

[Problems to be Solved by the Invention] However, the method and device for releasing a plastic lens from a mold using a vise and a cutter described in (1) above do not involve directly applying a sharp cutter to the interface between the lens mold assembly and the mold. Since the mold must be inserted and then peeled off, the mold release process not only requires great skill, but also damages the outer peripheral surfaces of the plastic lens and mold, resulting in a decisive problem of poor quality and yield of the plastic lens. Moreover, there was a problem in that productivity was extremely low because the operator had to peel off the plastic lenses one by one from the lens mold assembly.

In addition, the above-mentioned mold release method using warm water and its equipment are as follows:
Because the plastic lens or mold is rapidly cooled after being immersed in a hot water tank, cracks may appear in the plastic lens or mold, and dirt that adhered to the lens mold assembly may become loose and accumulate in the hot water tank due to the immersion process, which involves changing electricity in the hot water tank. However, there were problems such as this dirt adhering to the plastic lens during the mold release process and causing quality problems, and this method did not solve the above problem.

This invention solves the above problems and eliminates the need for the operator to have any skill when releasing a plastic lens from a lens mold assembly (in addition, there are no scratches or cracks on the plastic lens or mold). It is an object of the present invention to provide a mold release method and a device for the mold release method that do not cause such problems.

[Means for Solving the Problems] In order to achieve the above object, the mold release device for plastic lenses according to the present invention has a structure in which a mold having a certain gap and made of an inorganic material has a heat-curing material in the gap. A plastic lens is formed by injecting and solidifying a plastic resin, and for a lens-shaped assembly in which the mold and the plastic lens are integrated, the absorption rate of the plastic lens is higher than the absorption rate of the mold. The present invention is characterized in that the plastic lens is released from the mold due to a difference in thermal expansion generated between the mold and the plastic lens by heating by irradiating far infrared rays in a large wavelength range.

Here, examples of the inorganic mold include glass as described in the prior art section, as well as ceramics and the like.

Examples of thermosetting resins that are materials for plastic lenses include diethylene glycol bisallyl carbonate, acrylic esters, diallyl esters, and triallyl isocyanate, which are commonly used as materials for plastic lenses.

The reason why plastic lenses emit far infrared rays in a wavelength range where the absorption rate is higher than that of molds is because the absorption rate of far infrared rays in this wavelength range is low for molds, but high for plastic lenses. In other words, a mold is difficult to absorb far infrared rays, whereas a plastic lens easily absorbs far infrared rays, so a difference in thermal expansion is likely to occur between the two. In order to generate this thermal expansion difference more effectively, it is preferable to select a wavelength range in which the absorption coefficient of the plastic lens is 10% or more higher than that of the plastic lens. Such a relationship with the far-infrared absorption chart wavelength range can be easily determined from the characteristic curves of the mold and plastic lens. Further, it is preferable that the heating temperature of the lens-shaped assembly is 60 to 150[deg.] C., since this will generate a sufficient difference in thermal expansion in the boundary layer between the two.

In this case, in order to generate a larger difference in thermal expansion between the two, from among the above mold and plastic lens, a mold with a linear expansion coefficient of 5x106 to 15x10-6 and a mold with a linear expansion coefficient of 5xio- 5~17x10-
Preferably, the plastic lens of No. 5 is selected to form a lens-shaped assembly. The coefficient of linear expansion of this mold and plastic lens can be measured using a linear dilatometer.

Further, when releasing a plastic lens from a lens mold assembly, the releasing operation becomes even easier if the following embodiments are used in combination.

The object to be processed in the present invention is a mold obtained by injecting resin into the cavity formed between the molds 1 and 2 and solidifying the resin, and then removing the gasket 3 and the clip 5, as explained in FIG. 1.2 and a plastic lens L.

■ The direction in which the lens-shaped assembly is placed on the conveying means is determined by the third direction.
Although there are the vertical direction shown in the figure, the horizontal direction rotated 90 degrees to the left or right from this state, or the diagonal direction, the vertical direction is preferable.

This is because when the lens mold assembly reaches the above temperature, the plastic lens slides off from the lens mold assembly due to gravity.

■ When far-infrared rays are irradiated while blowing cold air with a temperature of 40°C or less onto the lens-shaped assembly 6, the plastic side with a larger coefficient of linear expansion will heat up and expand first, which improves mold release properties and is more preferable. .

In addition, with this embodiment, the mold is pushed away from the lens mold assembly by the cold air, and the plastic lens can be cooled at the same time, making it easier to handle the plastic lens after it has been released. Mold work can be done efficiently.

Next, in order to achieve the above object, the mold release device for plastic lenses according to the present invention has a structure in which a thermosetting resin is injected into the gap of an inorganic mold having a certain gap and hardened to form a plastic lens. In a plastic lens mold release device for releasing the plastic lens from a lens mold assembly in which the mold and the plastic lens are integrated, (a) the lens mold assembly includes: a box forming a heating chamber; (b) a far-infrared heater provided within the box; (c) wavelength range adjustment means for the far-infrared heater; and (d) the lens-shaped assembly within the box. A conveyance means for carrying in and out, and the following.

Here, the box is a heating container for storing a far-infrared heater inside, and the box may be of any shape as long as it has an entrance/exit for the lens-shaped assembly. It also includes shapes and tunnels. usually,
Normally, such a box is equipped with a circulation fan, an exhaust fan, etc., and takes the form of a dryer, but the mold release device of the present invention uses a mold and a plastic lens as its release principle. Since this technology utilizes the difference in thermal expansion between the plastic lenses, the plastic lens is heated while the mold located on the outer surface is not provided with a circulation fan to promote the generation of this difference in thermal expansion. Rather, it is preferable to provide cooling means for the mold, such as a dedicated cooling fan or exhaust fan, to prevent hot air from filling the inside.

Far infrared heaters are not particularly limited;
For example, far-infrared heaters such as well-known sheathed heaters and plate heaters can be used.

In addition, the heating capacity of the far infrared heater is 6.
As long as it can be heated to a temperature of about 0 to 1508 C (Such heating capacity should be determined by taking into consideration the heat capacity of the lens-shaped assembly, the conveying speed of the conveying means, the amount of heat dissipated from the box, etc.) I can do it.

The far-infrared heater wavelength range adjustment means means means that can adjust the wavelength range of the far-infrared heater provided inside the box to a desired wavelength range. Since far-infrared rays emit far-infrared rays in a specific wavelength range corresponding to the heating temperature, as far-infrared wavelength range adjustment means, a voltage control method such as a thyristor, which is a known adjustment means to a desired heating temperature, can be used. A resistance control method such as a slider, a current control method, etc. can be used.

The transportation means refers to the means for transporting the lens-shaped assembly into and out of the box, for example, it may be simply a rack made of metal, wood, etc. that is manually inserted into the box by an operator as necessary. However, it is preferable to use a net conveyor, chain conveyor, bar conveyor, etc., which can be moved in and out of the box by a driving means such as a motor.

[Operation] The mold release method and device for a plastic lens of the present invention configured as described above is applicable to a lens mold assembly composed of an inorganic mold and a plastic lens. When the lens is heated by being irradiated with far-infrared rays in a wavelength range where the absorption rate is higher than that of the mold, the mold does not absorb much of the far-infrared rays, while the lens selectively absorbs the far-infrared rays. do.

Therefore, only the lens is heated intensively, a large difference in linear expansion occurs at the interface between the mold and the lens, peeling occurs at the interface between the two, and the lens is released from the mold.

[Example 1] Hereinafter, an example of a mold release method for a plastic lens and an apparatus therefor according to the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic vertical sectional view of a mold release device for plastic lenses according to the present invention.

In the figure, reference numeral 6 denotes the lens-shaped assembly shown in FIG. 3, and a plurality of them are placed on a metal rack 25 at a constant pitch in the vertical direction. 7 is a net conveyor that conveys the rack in the direction of the arrow in the figure, which has a constant width in the direction perpendicular to the plane of the paper, and is wound endlessly around guide rolls 8.9 and drive rolls 10. has been done. Drive roll 1
0 can be driven by a motor 12 with a transmission via a chino 11, and the lens-shaped assemblies 6 placed on a rack 25 can be transported one after another into the main body 13, which is a box. I can do it. Therefore, these racks 25, net conveyor 7, guide rolls 8.9, drive rolls 10,
A conveyance means is constituted by a chino 11 and a motor 12 with a transmission. In this example, the conveyance means has a width of 500 mm.
The net conveyor can be driven by a 0.75kW motor with a continuously variable transmission.

The main body 13 is a box-shaped heating container having walls of a constant thickness,
It has a heat insulating structure with a heat insulating material (not shown) provided on the inner wall surface, and on the left and right sides there are slit-shaped entrances 26 through which the lens-shaped assembly 6 placed on the net conveyor 7 enters and exits.
and an outlet 27 are provided. In this embodiment, the length between the inner walls of the main body is 3 m1, the opening width of the opening 26 and the outlet 27 is 550 mm, and the height thereof is 200 mm.

Inside the main body 13, a plurality of rod-shaped far-infrared heaters 18 supported by brackets 17 on an upper partition member 14 and a lower partition member 15, which will be described later, are arranged at a constant pitch along the traveling direction of the net conveyor 7. has been done. The far-infrared heater 18 is fixed to a bracket 17 together with a reflector 19, and since the bracket 17 can be moved vertically by a height adjustment section 20 provided on each partition member, the irradiation distance to the lens-shaped assembly 6 can be adjusted. can be adjusted. In this embodiment, as far-infrared heaters 18, 90 sheathed heaters each having a length of 500 mm are fixed at a position 70 mm above the lens-shaped assembly 6.

The upper partition member 14 and the lower partition member 15 provided at the upper and lower parts of the bracket 17 are for forming a heating chamber H in the mold release device by partitioning the inside of the main body with these two members. be.

Further, 21 connected to the upper partition member 14 is a suction duct for introducing outside air into the heating chamber H, and a lower partition member 1
5, 23 is an exhaust duct for discharging the outside air introduced into the heating chamber H, and 24 is an exhaust duct for discharging the outside air introduced into the heating chamber H to the outside through the exhaust duct 23. I'm a fan. Note that 22a and 22b are dampers that adjust the amount of outside air supplied and discharged, 22c is a damper that adjusts the amount of circulation within the heating chamber, and 16 is a perforated plate, for example, to uniform the flow of outside air within the heating chamber. This is a rectifying plate composed of , net screen, etc. Therefore, these members 16.21 to 24 constitute the cooling means for the mold 1.2.

The mold releasing method of the present invention was carried out in the following manner for the mold releasing apparatus of FIGS. 1 and 3 constructed as described above.

First, by adjusting the voltage of the far-infrared heater 18 with a voltage regulator (not shown) and setting its surface temperature to 200°C, the wavelength range of the far-infrared rays emitted from the heater is
7 μm and the temperature in the heating chamber H was adjusted to 120° C. with the exhaust fan 24 being driven.

Next, the gasket 3 and clip 5 are removed from the lens mold assembly 6.
After removing the
A lens mold assembly 6 consisting of a glass mold 1.2 of X10-6 and a plastic lens L2 of linear expansion coefficient of 14X10-5 is placed vertically at intervals of 30 mm, and It was transported into the main body at a transport speed of 0°3 m/min (approximately 10 minutes in far-infrared irradiation time).

Figure 2 shows the far-infrared absorption state of the mold 1.2 and the plastic lens I7 in the heating chamber H in this state. Explain.

Figure 2 shows the absorption rate of far infrared rays on the vertical axis and the wavelength of far infrared rays on the horizontal axis.As shown in this figure, when the wavelength range of far infrared rays is 5 to 7 μm, glass The absorption rate of a plastic mold is lower than that of a plastic lens, while the absorption rate of a plastic lens is high. In other words, the mold has difficulty absorbing far infrared rays, while the plastic lens has a tendency to absorb far infrared rays. Therefore, only the plastic lens is selectively heated. Furthermore, the outer surface of the mold 1.2 is cooled by outside air introduced into the heating chamber H by an exhaust fan 24. Therefore, in the heating chamber H, the mold release of the plastic lens is likely to be promoted.

Then, from the rack 25 that is sequentially carried out from the exit 27,
When the operator took out the lens mold assembly 6 and examined it, it was found that the plastic lens L had slipped from the mold 1.2 and had been released from the mold 1.2.

Incidentally, in order to confirm the effect of the mold release work using the mold release device of this example, we compared the conventional manual mold release work with the following tests: ■ Lens dirt, ■ Lens quality (occurrence of surface dirt, scratches, cracks, etc.). A comparison was made on four points: (1) production capacity, and (2) ease of mold release, and the results are shown in the following table.

Table As is clear from this table, the plastic lens mold release method and its device according to the present invention have significantly superior effects compared to the conventional mold release method and its device. I understand.

[Effects of the Invention] As explained above, the method for releasing a plastic lens according to the present invention is applicable to a lens mold assembly composed of an inorganic mold and a plastic lens. The mold is heated by irradiating far infrared rays in a wavelength range where the absorption rate of far infrared rays is higher than that of the mold, so the mold has difficulty absorbing far infrared rays, whereas the lens easily absorbs far infrared rays. As a result, a large difference in linear expansion occurs at the interface between the mold and the lens, and the lens can be easily released from the mold.

Furthermore, the mold release device for plastic lenses according to the present invention transports the lens mold assembly by a transport means into a box having a far-infrared heater therein, and adjusts the wavelength range of the heater by a wavelength range adjustment means. Therefore, when an operator releases a plastic lens from a lens mold assembly, no skill is required.

Furthermore, unlike conventional mold releasing methods and devices, the mold releasing method and its device of the present invention do not use a sharp knife or rapidly cool the lens after heating it with hot water when molding a plastic lens. Excellent effects such as no scratches or cracks on the mold can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view of a mold release device used to carry out the mold release method for plastic lenses according to the present invention, and FIG. 2 shows the far-infrared absorption state of the plastic lens and the glass mold. The characteristic diagram, FIG. 3, is a schematic longitudinal sectional view of the lens-shaped assembly shown in FIG. 1.2: Mold 3: Gasket 4: Inlet 5: Clip 6: Lens mold assembly 7: Net conveyor 8.9 Ni guide roll 10: Drive roll 11: Cheno 12: Motor main body with transmission Upper partition material Lower partition Material rectifier plate bracket Far-infrared heater: Reflector: Height adjustment section: Suction duct: Damper: Exhaust duct Exhaust fan rack Inlet outlet Heating chamber Plastic lens S: Gap 13:

Claims (5)

[Claims] (1) A plastic lens is formed by injecting and solidifying a thermosetting resin into the gap of an inorganic mold having a certain gap, and the mold and the plastic lens are integrated. By irradiating and heating the mold assembly with far infrared rays in a wavelength range in which the absorption rate of the plastic lens is higher than the absorption rate of the mold, a phenomenon occurs between the mold and the plastic lens. A method for releasing a plastic lens, the method comprising releasing the plastic lens from the mold using differential thermal expansion. (2) The wavelength range of far infrared rays is far infrared rays in a wavelength range where the absorption rate of the plastic lens is 10% or more higher than the far infrared absorption rate of the mold, and the heating temperature of the lens mold assembly is: The method for releasing a plastic lens according to claim 1, wherein the temperature is 60 to 150°C. (3) The linear expansion coefficient of the lens-shaped assembly is 5×10^-^6
~15×10^-^6 mold and linear expansion coefficient of 5×
10. The method for releasing a plastic lens according to claim 1, further comprising a plastic lens having a size of 10^-^5 to 17 x 10^-^5. (4) A plastic lens is formed by injecting and solidifying a thermosetting resin into the gap of an inorganic mold having a certain gap, and the mold and the plastic lens are integrated. A plastic lens mold release device that releases the plastic lens from the mold assembly includes: (a) a box forming a heating chamber for the lens mold assembly; and (b) a remote control provided inside the box. A plastic product comprising: an infrared heater; (c) a means for adjusting the wavelength range of the far-infrared heater; and (d) a conveyance means for carrying the lens-shaped assembly into and out of the box. Lens release device. (5) The mold release device for plastic lenses according to claim (4), further comprising a cooling means for cooling the mold.