JPH0796527A - Production of front surface mirror - Google Patents

Abstract

PURPOSE:To obtain a front surface minor enhanced in accuracy while reducing the remaining of air and strain by holding a plate to be processed between a mold and a lid to heat the same and evacuating the space between the plate to be processed and the mold to supply a fluid into the space between the lid and the plate to be processed under pressure and gradually cooling the plate to be processed thereafter to coat the same with a mirror surface forming material. CONSTITUTION:A mold 12 having a molding surface 13, the lid 9 of a cavity 10, the fluid compressor supplying a compressed fluid into the cavity 10 and the vacuum pump 2 discharging the air in the space 101 between a resin plate 11 and the molding surface 13 are provided. After the mold is heated by a heating device 3 and the cavity 10 is evacuated by the vacuum pump 2, pressurization is started by the fluid compressor 1 before the resin plate reaches its deformation temp. As a result, the close contact of the resin plate 11 with the mold 12 from the end part of the mold to the center part and vent hole 18 of the mold is performed and the remaining of air between the resin plate and the mold is eliminated to press the rear surface 15 of the resin plate 11 to the molding surface 13 to enable the molding of the resin plate. The resin plate is cooled to curing temp. while pressurization and evacuation are performed or after evacuation is stopped. Then, a mirror surface is formed on the resin plate by the vapor deposition of aluminum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a surface mirror used for a solar furnace, a display, etc. by condensing or collimating light from the sun, laser, etc.

[0002]

2. Description of the Related Art Conventionally, a method for manufacturing a surface mirror has been disclosed in Japanese Patent Laid-Open No. HEI-2
As shown in No. 235729, there is a pressing method using a die in which two or more sets of upper die and lower die which face each other are provided.

[0003]

However, in order to obtain an accurate mirror surface, the surface of the die has to be processed into a mirror surface, and the cost of the apparatus becomes very high. Also,
In addition to this, vacuum forming or pressure forming is conceivable, but a slight air residue occurs between the forming die and the processing plate, and this air residue becomes a cause of a shape error in high-precision surface mirror fabrication.

Further, since the processed plate expands when heated and contracts when cooled, the conventional clamping method of simply sandwiching the processed plate causes problems such as air leakage during pressurization and distortion during contraction. There is.

[0005]

In order to solve the above-mentioned problems, the first invention provides a molding die having a molding die surface corresponding to the shape of a surface mirror to be obtained, and a space on the molding die surface side. A vacuum that makes the space between the closing plate, the fluid pressurizing device for supplying fluid to the space between the lid and the processing plate to be processed, and the mold surface of the molding die a vacuum state. Using a forming device equipped with a vacuum pump for pulling and a heating device for heating the processed plate, the processed plate is sandwiched between the molding die and the lid, the processed plate is heated by the heating device, and the processed plate is processed by the vacuum pump. The vacuum of the space between the mold and the mold surface is started, and the space between the lid and the work plate is set by the fluid pressure device before the work plate reaches the heat deformation temperature while the work plate remains heated. Fluid is supplied and pressurized to form a work plate, and heating is stopped after the work plate reaches the specified temperature. Pressurization / vacuum drawing or gradual cooling in a state where vacuum drawing is stopped while pressure is applied, then take out the processed plate molded into the shape of a surface mirror from the molding die and coat the surface with a mirror-forming material. It adopts technical means.

Further, according to the second aspect of the present invention, even if the thickness of the working plate changes during molding of the working plate, the space between the lid and the working plate and the space between the working plate and the mold surface of the forming die. The technical means of using a molding apparatus provided with a plate thickness fluctuation absorbing mechanism that secures the seal of (1) and expands and contracts the lid pressing the processing plate according to the plate thickness fluctuation of the processing plate. Further, the third aspect of the present invention employs technical means in which the fluid pressurizing device and the heating device are both used by the hot air generating device. In this case, first, only hot air is supplied without applying pressure, and thereafter, pressurization with hot air is started before the processed plate reaches the heat distortion temperature.

Further, the fourth aspect of the present invention employs a technical means in which the applied pressure is gradually increased and the pressurization pattern reaches a predetermined pressure. The fifth aspect of the present invention takes the technical means of rapidly increasing the pressing force after the completion of the close contact of the work plate with the molding die surface. The sixth aspect of the present invention takes the technical means of using a molding apparatus having a molding die surface in which variations in the thickness of the machined plate after molding have been offset in advance.

[0008]

According to the first aspect of the present invention, the forming die and the working plate are the last so that the working plate plucks the vacuum drawing hole of the forming mold and adheres closely to the forming die surface without air remaining, and hardly deforms even after cooling and taking out. A surface mirror is obtained. According to the second aspect of the present invention, sealing can be surely performed.

In the third aspect of the invention, the fluid pressurizing device and the heating device are integrated, so that the entire device becomes compact. In the fourth aspect of the present invention, since the processed plate is more closely adhered to the surface of the molding die, the distortion of the surface mirror after cooling and extraction is further reduced. Book 5
In the invention, since the working plate is pressed with a small force when it is deformed, it is possible to block the vacuum drawing hole first before the working plate is completely adhered to the molding die surface without being molded at once. Disappear.

In the sixth aspect, the shape error of the surface mirror can be reduced.

[0011]

EXAMPLES Examples of the present invention will be described below. In the example, an example using a resin plate as a processed plate will be described. First, as shown in FIG. 1, a forming die 12 having a forming die surface 13 corresponding to the shape of a surface mirror to be obtained in consideration of the plate thickness after forming, and a forming die 12 which is a first space. The lid 9 for closing the upper part of the cavity 10 and the cavity 1
Second space 1 between the fluid pressurizing device 1 for supplying the pressurized fluid 14 to the inside of the 0, the back surface 15 of the resin plate 11 and the mold surface 13.
The vacuum pump 2 and the heating device 3 for discharging the air 01 are prepared.

The molding die 12 is made of metal, and the molding die surface 13 is accurately cut in consideration of the variation in the plate thickness due to the molding of the resin plate 11. An air vent hole 18 is formed through the center of the mold 12.
It is preferable that the diameter of the air vent hole is small enough not to affect the surface 17 of the resin plate 11 due to the resin meat being pulled by vacuuming. As shown in FIG. 4, if only the diameter on the molding die surface 13 side is reduced, the degree of vacuum can be increased and the hole diameter can be reduced.

A ring type seal 1 is provided between the lid 9 and the front surface 17 of the resin plate 11 and between the molding die surface 13 and the back surface 15 of the resin plate 11.
6 are arranged. The seal 16 is made of heat resistant rubber. In addition, as shown in FIGS. 3A and 3B, the upper plate 5 and the lid 9 have bolt insertion holes 22 and 23, respectively.
Are fastened by bolts 4 as shown in the figure. The spring 8 expands and contracts when the thickness of the resin plate 11 changes, and the lid 9 moves up and down with respect to the bolt 4 to perform an appropriate seal against pressure and vacuum drawing. Here, the bolt 4, the upper plate 5,
The spring 8, the lid 9, and the seal 16 constitute a plate thickness fluctuation absorbing mechanism that can appropriately perform processing and vacuuming even when the resin plate plate thickness changes.

The heating device 3 may be a device that uses electric heating or hot air. As the fluid pressurizing device 1, a pump,
There is a compressor, etc., and the pressure can be controlled by a valve or the like. The pressurized fluid may be a fluid such as nitrogen or air. The material of the resin plate 11 is acrylic resin, ABS
A thermoplastic amorphous resin such as a resin is used. The thickness of the resin plate is preferably about 3 mm. If it is too thin, it will be difficult to maintain its shape, and if it is too thick, molding will be difficult.

A glass material such as Pyrex glass may be used as the material of the processed plate. Next, a method of manufacturing the surface mirror will be described. First, the seal 16 and the resin plate 11 to be molded are placed on the molding die 12, and the lid 9 with the seal 16 is fitted.
Is closed, the spring 8 is arranged on the upper surface of the lid 9, and the peripheral portion of the resin plate is fixed with the upper plate 5, the lid 9 and the molding die 12 by the bolt 4.

FIG. 2 shows molding conditions for heating, pressurizing and vacuuming. First, heating by the heating device 3, by the vacuum pump 2,
Start evacuation. Although the resin plate temperature rises as shown in FIG. 2, before the time t _{1 at} which the temperature T1 at which the resin begins to deform due to heating is reached, the fluid pressurizing device 1 starts pressurizing at time t ₂ . (T ₂ <t ₁ ) By applying pressure at the above timing, as shown in FIG. 6, the resin plate 11 and the molding die 12 are moved from the die end portion 19 to the die center portion to the air vent hole 18 in the arrow direction 20. Can be closely adhered to each other, and the back surface 15 of the resin plate 11 is fixed to the mold surface 1 so that no air remains between the resin plate 11 and the molding die 12.
It can be molded by pressing to 3.

If pressure is applied at the timing of t ₂ ≧ t ₁ , the resin plate 11 is sucked into the air vent hole 18 as shown in FIG. After that, the resin plate is cured by cooling it to the curing temperature of the resin while pressing the resin plate while pressing the resin plate or pressing the resin plate while stopping the vacuuming while pressing the resin plate. Then, the pressurization and the vacuum evacuation are stopped, the pressurized fluid in the cavity 10 is caused to flow out, and the molded and cured resin plate is removed from the cavity 1
Take out from within 0. Then, a mirror surface is formed on the surface 17 of the resin plate by aluminum vapor deposition, plating or the like to obtain a resin surface mirror.

In the second embodiment, as shown in FIGS. 5 (a) and 5 (b), the vacuum drawing may be a multi-point drawing. In one-point drawing, the resin is pulled from there and the shape error due to the plate thickness distribution becomes large, but by performing multi-point drawing as described above, uniform vacuum drawing is possible and the plate thickness difference becomes small. In the third embodiment, the pressing force is not kept constant from the beginning, and the pressing force is gradually increased at a low pressure as shown in FIG. 8 at the time when the adhesion of the resin plate 11 to the molding die surface 13 is completed. By rapidly increasing the applied pressure from t ₃ and then applying a constant pressure, ideal adhesion of the resin plate backside to the mold surface can be performed so that the resin plate is not drawn into the air vent hole 18 during molding. .

As a fourth embodiment, as shown in FIG. 9, the heating device 3 may be provided inside the molding die 12 and the lid 9. Also in this example, the structure of the device is small, and a surface mirror with high accuracy can be formed. In the fifth embodiment, the die surface is made of a porous material as shown in FIG. Also in this example, a uniform vacuum can be drawn as in the other examples.

As a sixth embodiment, as shown in FIG. 11, a hot air generator 3 may be used as a liquid pressure device and a heating device. Also in this example, the surface mirror can be formed with a small structure and high precision. In the seventh embodiment, the molding die surface is formed by offsetting the plate thickness distribution when the concave surface is formed. FIG. 12 shows the plate thickness distribution when the concave surface is formed. Since the central portion is thinner, the offset of the mold surface 13 may be shallower toward the central portion.

[0021]

According to the first aspect of the present invention, it is possible to realize a surface mirror in which no air residue is left between the work plate and the molding die and the distortion is small during cooling, and it is possible to manufacture a highly accurate surface mirror. .
According to the second aspect of the present invention, the sealing at the time of suction / pressurization becomes reliable, so that reliable molding can be performed and the defective rate of the product can be reduced.

According to the third aspect of the invention, the device is simplified,
Can be miniaturized. According to the fourth and fifth aspects of the present invention, since the working plate is firmly attached to the molding die surface, it is possible to manufacture the surface mirror with higher accuracy. According to the sixth aspect of the present invention, it is possible to preliminarily correct variations in the plate thickness of the processed plate, so that it is possible to manufacture a surface mirror with extremely high accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view of a molding apparatus used in a first embodiment of the present invention.

FIG. 2 is a graph showing molding conditions such as heating, pressurizing and vacuuming according to the present invention.

3A is a plan view of an upper plate 5, and FIG. 3B is a plan view of a lid 9.

FIG. 4 is a vertical sectional view of a forming die.

5A is a plan view of a molding die according to a second embodiment of the present invention, and FIG. 5B is a sectional view of the molding die.

FIG. 6 is a sectional view illustrating a molding process according to the first embodiment.

FIG. 7 is a cross-sectional view showing a molded state of a resin plate when pressure is applied after reaching a resin deformation temperature.

FIG. 8 is a graph showing a pressurizing pattern of the liquid pressurizing device according to the third embodiment.

FIG. 9 is a sectional view of a molding apparatus used in the fourth embodiment.

FIG. 10 is a cross-sectional view of a molding device used in the fifth embodiment.

FIG. 11 is a cross-sectional view of a molding device used in the sixth embodiment.

FIG. 12 is a graph showing a plate thickness distribution when a concave surface is formed according to the seventh embodiment.

[Explanation of symbols]

1 Fluid Pressurizing Device 2 Vacuum Pump 3 Pressurizing Device 4, 5, 8, 9, 16 Bolt, Upper Plate, Spring, Lid, Seal (Plate Thickness Variation Absorbing Mechanism) 10 Cavity (First Space) 11 Resin Plate ( Processed plate) 12 Mold 13 Mold surface 101 Second space

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area // B29L 11:00

Claims (6)

[Claims] 1. A molding die having a molding die surface corresponding to the shape of a surface mirror to be obtained, a lid closing a space on the molding die surface side, and the lid and a work plate to be formed. Fluid pressurizing device for supplying fluid to the space, a vacuum pump for vacuuming the space between the working plate and the mold surface of the mold, and heating for heating the working plate. Using a molding device provided with a device, sandwiching the processing plate between the molding die and the lid, heating the processing plate by the heating device, the mold of the processing plate and the molding die by the vacuum pump The vacuuming of the space between the surface and the surface is started by the fluid pressurizing device in the space between the lid and the processing plate before the processing plate reaches the heat deformation temperature in the heated state of the processing plate. Fluid is supplied and pressurized to form the work plate, and the work plate is heated to a predetermined temperature. After reaching the temperature, the heating is stopped and gradually cooled in a pressurized state, then, the processed plate molded into the shape of a surface mirror is taken out from the molding die, and the surface thereof is coated with a mirror surface forming material. Surface mirror manufacturing method. 2. Even if the plate thickness of the work plate changes at the time of forming the work plate, the space between the lid and the work plate and the space between the work plate and the mold surface of the forming die are sealed. The method for manufacturing a surface mirror according to claim 1, wherein a molding apparatus having a plate thickness fluctuation absorbing mechanism that expands and contracts a lid that presses the processing plate according to a plate thickness fluctuation of the processing plate is used. 3. The method for manufacturing a surface mirror according to claim 1, wherein the fluid pressurizing device and the heating device are both used by the hot air generating device. 4. The method of manufacturing a surface mirror according to claim 1, wherein the pressing force is gradually increased to reach a predetermined pressure. 5. The method of manufacturing a surface mirror according to claim 1, wherein the pressing force is set small until the working plate is brought into close contact with the molding die surface. 6. The method of manufacturing a surface mirror according to claim 1, wherein the surface mirror is manufactured by a molding apparatus having a molding die surface in which variations in the plate thickness of the processed plate are offset in advance.