JPH101320A - Mold and molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of stably producing many pieces of molded articles having uniform shapes and a mold capable of executing this method. SOLUTION: This mold has an upper mold 2 having a molding surface on its rear surface, a lower mold 4 having a molding surface on its front surface, >=1 intermediate molds 3a, 3b having molding surfaces on both front and rear surfaces and inter-mold space determining means. This molding method includes stages of introducing a previously heated and softened blank 1 for molding between the molding surfaces facing each other of the two adjacent molds of the mold or introducing the blank 1 for molding, softening the blank by heating, applying a pressure on the upper mold 2 or the lower mold 4 or both thereof and setting the spacings between the respective molds by the inter-mold space determining means 5a, 5b, 5c, thereby press molding the blank 1 for molding, then cooling the molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a molding die and a molding method. In particular, the present invention relates to a technique for precisely molding an optical lens or a glass optical element having a fine groove or a concavo-convex pattern on the surface.

[0002]

2. Description of the Related Art In recent years, a method of molding a glass lens with high precision without polishing after pressure molding has been actively practiced. One example of such a method is disclosed in JP-A-52-45.
No. 613 discloses a method. According to this method, first, the temperature of the glass material and the mold are raised to near the softening point of the glass in a non-oxidizing atmosphere. Then, when the temperature of the glass and the mold becomes substantially equal, the glass is pressed by the mold.
Thereafter, the mold temperature is lowered to the glass transition point or lower while maintaining the pressure, and the molded product is taken out by cooling under normal pressure. Although this method does not require polishing after removing the molded product, it has a problem that the cycle time required for molding is extremely long.

[0003] Therefore, a method for efficiently producing many molded products was studied, and a new molding die was developed. For example,
Japanese Patent Application Laid-Open No. 63-64931 discloses a molding die having an upper die, a plurality of intermediate dies, and a lower die arranged in order in the axial direction of the pressing force and having a body die surrounding these. If a molding material is introduced between the upper mold and the middle mold and between the middle mold and the lower mold, and heat-softened and pressure-molded, a large number of molded articles can be manufactured at one time. Further, Japanese Patent Laid-Open No.
No. 176240 also discloses a mold having an upper mold, an intermediate mold, a lower mold, and a body mold surrounding them.

[0004]

However, when pressure molding is performed using these molding dies, since the pressing force is not evenly transmitted to the molding material, the elongation of the molding material differs depending on the molding location. Problem. If the molding material is excessively stretched, the molding material may protrude to the boundary between the body die and the molding die, and the corners of the molding die may be damaged, so that stable molding cannot be expected. In addition, the molded product to be manufactured is a thin defective product in which the protruding portion is missing. Conversely, if the elongation of the molding material is too small, a defective product having a large thickness and a small diameter will be produced.

[0005] Due to these problems, satisfactory methods cannot be efficiently produced by the conventional method. Also, there is no literature that suggests a solution to such a problem. Accordingly, the present inventors have conducted intensive studies to address these problems and to provide a method for efficiently producing a large number of satisfactory molded products and a mold capable of implementing the method. Was. In addition, the present inventors have made the operation during molding easier,
The present inventors have conducted intensive studies for the purpose of providing a method capable of stably producing a large number of molded articles having a uniform shape and a mold capable of implementing the method.

[0006]

These objects have been achieved by the present invention described below. That is, the present invention relates to an upper die having a molding surface on a lower surface, a lower die having a molding surface on an upper surface, one or more intermediate dies having molding surfaces on both upper and lower surfaces, and a molding die having a mold interval determining means. Furthermore, the present invention introduces a pre-heat-softened molding material between facing molding surfaces of two adjacent molds of a molding die, or introduces a molding material and heat-softens the upper mold, The present invention relates to a molding method including a step of applying pressure to a lower mold or both of them to set each mold interval to an interval set by a mold interval determining means, thereby pressing and molding a molding material, and a cooling step.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a mold and a molding method of the present invention will be described in detail in order. Mold The mold according to the present invention is characterized in that it has a mold interval determining means. The mold interval determining means is means for determining the interval between the upper mold and the intermediate mold, the interval between the intermediate mold and the adjacent intermediate mold when there are a plurality of intermediate molds, and the interval between the intermediate mold and the lower mold.
When molding using the molding die of the present invention, first, a molding material is introduced between the dies. At this time, the space between the molds is usually opened by the thickness of the introduced molding material. Thereafter, when pressure is applied, the space between the molds is reduced, and the mold and the mold space determination means come into contact with each other and are maintained at a constant mold space. At this time, the molding material is compressed into a space surrounded by the lower surface of the upper mold, the upper surface of the lower mold, and the mold interval determining means. As described above, the mold interval determining means determines the mold interval during pressure molding. That is, the mold interval determining means determines the thickness of the molded product and plays a role in preventing the molding material from protruding during the pressure molding. Further, the mold interval determining means also plays a role of preventing the upper and lower molding surfaces from being displaced due to the inclination of the intermediate mold during the pressure molding. Such a mold interval determining means has never existed in a conventional molding die.

[0008] The shape of the mold interval determining means is appropriately determined according to the shape of the mold and the molding surface provided on the mold. For example,
If the mold and the molding surface are circular, the mold interval determining means is generally formed in a ring shape. Further, the mold interval determination means may be fixed in advance to either the upper mold or the lower mold. Further, the mold interval determining means may be provided as an independent member for each mold, or one member may determine between a plurality of molds. As an example of the latter, for example, a single member fixed to both the upper and lower surfaces of the intermediate mold, whereby the distance between the intermediate mold and the mold above it, and the distance between the intermediate mold and the mold below it Can be determined.

The material of the mold interval determining means is selected from those which can withstand heating during the molding process. In particular, it is preferable to use a material having a larger coefficient of thermal expansion than the molding material to be used. If the mold interval determining means of such a material is provided, it is possible to cool under pressure while keeping the upper and lower portions of the molded body in contact with the mold after the pressure molding. That is, since the shrinkage of the mold interval determining means due to cooling is greater than the shrinkage of the molded body, pressure from above and below the molded body is directed to the molded body instead of the mold interval determining means. Therefore, by adopting such an embodiment, it is possible to contact the upper and lower surfaces of the molded body with the mold and to cool the molded body through the transition point in a pressurized state, thereby improving the surface accuracy. However, in this case, the volume of the molding material to be introduced into the molding die is set such that part or all of the outer peripheral portion of the molded body does not come into contact with the inside of the mold interval determination means at the time of pressure molding, and further, in the cooling step, Care should be taken that the compact is not clamped against the mold spacing determining means whose inner diameter has shrunk. This is because it is difficult to take out the compact that has been clamped by the mold interval determining means whose inner diameter has contracted.

The upper mold, the lower mold and the intermediate mold constituting the mold of the present invention may be of conventional shapes and materials. For example, JP-A-63-64931
And lower molds and intermediate molds specifically described in Japanese Unexamined Patent Application Publication No. Hei. The material is selected from those that do not undergo excessive deformation or deterioration due to heating during the molding process. For example, a cemented carbide hardly containing a metal binder can be used. Molding surfaces are provided on the lower surface of the upper die, the upper and lower surfaces of the intermediate die, and the upper surface of the lower die. The shape of the molded product is determined by the combination of the lower surface of the upper die and the upper surface of the intermediate die, the lower surface of the intermediate die and the upper surface of the intermediate die adjacent thereto, and the lower surface of the intermediate die and the upper surface of the lower die. Generally, one molding surface is provided on each of the lower surface of the upper die, the upper and lower surfaces of the intermediate die, and the upper surface of the lower die, but a plurality of molding surfaces may be provided. Further, the intermediate mold having the molding surfaces on both surfaces may be a mold in which two molds each having a molding surface on one surface are bonded together through the back surface. The molding surface is set in consideration of shrinkage of the molding material after heat molding. The processing of the molding surface can be performed using a technique well known in the field of the present invention, and examples thereof are given in Examples described later.

The number of intermediate molds constituting the mold of the present invention is one.
Above. If the number of intermediate molds is m and the number of molding surfaces provided on one surface of the mold is n, (m + 1) at a time
× n molded articles can be manufactured at one time. However, if the number m of the intermediate mold is excessively increased, care must be taken since unevenness in pressure propagation during pressure molding and lateral displacement of the mold are likely to occur, making it difficult to produce a uniform molded product.
However, the combined use of the mold sliding guide means and the lateral displacement prevention means described later is effective for preventing lateral displacement of the molding die, and the number m of the intermediate molds can be determined as appropriate in consideration of the presence or absence of the combined use.

The mold according to the present invention may be provided with mold sliding guide means. The mold sliding guide means is a means for guiding the sliding of the mold when the molding material is introduced or when pressure is applied. By providing the mold sliding guide means, the force due to pressurization can be uniformly applied to the mold without escaping in the lateral direction. Therefore, lateral displacement of the mold can be prevented, and a uniform molded product can be more reliably and efficiently manufactured. The mold sliding guide means is combined with the mold interval determining means to
It may be configured as one member, or different single members may each have a function as a mold sliding guide means and a function as a mold space determination means. Further, the mold of the present invention may be further provided with means for preventing the mold from laterally shifting. By providing the lateral displacement prevention means, it is possible to prevent deflection of the entire molding die due to pressurization and lateral displacement of the die. For this reason, as in the case of the mold sliding guide means, a uniform molded product can be more reliably and efficiently manufactured by installing the lateral displacement prevention means.
The lateral displacement prevention means may also have a function of guiding the mold sliding like a sleeve surrounding the upper mold, the intermediate mold, the lower mold and the mold interval determining means (third embodiment).

Molding method The molding method of the present invention is carried out using the above-mentioned molding die of the present invention. Since the type of molding material to be used is not particularly limited, a glass material or the like can be widely used. Typically, one type of molding material is used for one molding die. However, in some cases, two or more types of molding materials may be properly used according to the molding surface. The molding material is introduced between the opposing molding surfaces of two adjacent molds of the molding die to be heated and softened, or is heated and softened in advance and introduced. The introduction may be carried out as appropriate while assembling the molding die, or may be introduced into a previously assembled molding die. Next, pressure is applied to the upper mold, the lower mold, or both to set each mold interval to an interval set by the mold interval determining means. At this time, the pressure may be applied by pressing the center of the upper mold with a rod-shaped body or by applying pressure to the entire surface of the upper mold. Since the material for molding must be softened during pressurization, pressurization may be performed while heating. After the pressure molding in this manner, a molded product is obtained by cooling. Pressure molding and cooling are preferably performed in a nitrogen atmosphere because of high efficiency. In the present invention, when the forming material is a glass material, there is no limitation on the type of the glass material, and the forming conditions (softening temperature and pressurizing time of the glass at the time of forming) and cooling are determined according to the type of the glass. Conditions and the like can be determined as appropriate. The shape of the molded article obtained by the present invention is not particularly limited, and any molded article which has been known to be able to be molded by a precision press molding method can be similarly molded.

[0014]

The present invention will be further described with reference to the following examples. Example 1 FIG. 1A is a cross-sectional view of a molding die of the present invention into which glass materials 1a, 1b, and 1c have been introduced. This mold is made of heavy-crown optical glass (transition point: 515 ° C, yield point: 545 ° C)
Meniscus lens with an aspherical surface on one side (outer diameter 3
(0 mm, center thickness 4 mm). The heavy crown optical glass is 100 to 300.
The coefficient of thermal expansion measured at ° C. is 89 × 10 ⁻⁷ / ° C. The mold includes an upper mold 2 having a molding surface on a lower surface, intermediate dies 3a and 3b having molding surfaces on both upper and lower surfaces, a lower mold 4 having a molding surface on an upper surface, and a ring-shaped member (mold interval determining means + mold sliding). Guide means) 5aa, 5b and 5c. Type 2, 3
The molding surfaces 6 provided at a, 3b and 4 are formed by forming a platinum-based alloy thin film on an optical mirror surface. Looking from above,
The molds 2, 3a, 3b, 4 are circular, and the ring-shaped members 5
The clearances between a, 5b, 5c and the dies 2, 3a, 3b, 4 are narrowed to such an extent that no axial deviation of the molded product occurs. For these members, a cemented carbide containing almost no metal binder is used (thermal expansion coefficient 49 × 10 4).
^-7 / ° C).

Outside each molding surface 6, flat portions 7a, 7b,
7c, 9a, 9b, 9c are provided,
a, 7b, 7c so that the ring-shaped members 5a, 5c
b and 5c are provided respectively. Upper mold 2, middle mold 3
a and 3b can slide up and down on the inner surfaces of the rings of the ring-shaped members 5a, 5b and 5c. That is, the ring-shaped member also has a function of guiding the mold sliding. The downward sliding can be performed until the flat portions 9a, 9b, 9c outside the molding surface come into contact with the flat portions 8a, 8b, 8c of the ring-shaped member.

Using this mold, an optical glass was formed by the following method. The glass material was used as a molding material. This glass material 1a, 1b, 1c
As shown in FIG. 1A, between the upper mold 2 and the middle mold 3a, between the middle mold 3a and the middle mold 3b, and between the middle mold 3b and the lower mold 4
Between each introduced. The capacity of the introduced glass material was such that the peripheral portion 11 was rounded without the glass material protruding from the inner end portion 10 of the ring-shaped member at the time of pressure molding described later. After the introduction of the glass material, the upper mold 2 was pressed downward at 600 ° C. in a nitrogen atmosphere. After pressing for 1 minute, the flat portions 9a, 9b, 9c outside the molding surface come into contact with the flat portions 8a, 8b, 8c of the ring-shaped member.
The state shown in FIG. After cooling, the optical glass was taken out. As a result of repeating this molding method, the center thickness became constant, and an optical lens having good quality and performance required for a high-precision lens could be stably manufactured. All the molded products were within the allowable tolerance, and no defective products were out of the intended specifications.

Example 2 Using the mold described in Example 1, the optical glass was molded in accordance with the method described in Example 1, after changing the conditions a or b below. [Method a] Instead of a glass material that was not softened, a glass material that had been softened by heating to 600 ° C. in advance was introduced. [Method b] The step of pressing the glass material was performed in a vacuum state. Also in the case of the methods a and b of this embodiment, high-quality optical glass could be stably produced as in the case of the first embodiment.

Embodiment 3 FIG. 2 is a sectional view of another molding die of the present invention into which glass materials 1a, 1b, and 1c are introduced. This mold has ring-shaped members 5a, 5a on the outer periphery of the mold of Example 1 shown in FIG.
b, 5c are provided. The sleeve 12 plays a role as a means for preventing lateral displacement. Using this mold, an optical glass was formed in the same manner as in Example 1. The molded product after cooling was taken out by holding the sleeve, pushing up the lower mold 2 with an extruding rod, and sequentially disassembling it. As a result, it was confirmed that the use of the mold shown in FIG. 2 increased the stability of setting and pressure molding.

(Embodiment 4) FIG. 3 shows glass materials 1a and 1a.
It is sectional drawing of further another shaping | molding die of this invention which introduced b and 1c. This mold includes an upper mold 2, an intermediate mold 3a, 3b, a lower mold 4, a ring-shaped member (mold interval determining means) 5a, 5b, 5
c, and a sleeve 12. The sleeve 12 has a function of preventing lateral displacement of the mold and guiding the mold sliding. The ring-shaped members 5a, 5b, 5c
It has the function of determining the thickness of the molded product and preventing inclination of the upper and lower surfaces. For the molds 2, 3a, 3b, 4 and the sleeve 12, a cemented carbide containing almost no metal binder is used, and its thermal expansion coefficient is 49 × 10 ⁻⁷ / ° C. The ring-shaped members 5a, 5b, 5c have a size at the outer edge of the mold that does not protrude from the circumference, and have a thermal expansion coefficient of 180.
It is formed of stainless steel of × 10 ^-7 / ° C.

Each of the molding surfaces of the dies 2, 3a, 3b, and 4 has a platinum-based alloy thin film formed on an optical mirror surface. Outside each molding surface 6, as in FIG. 1, flat portions 7a, 7b, 7c,
9a, 9b and 9c are provided. The area of these flat parts is larger than the area of the flat parts of the ring-shaped members 5a, 5b, 5c that come into contact with each other. The clearance between the molds 2, 3a, 3b, 4 and the sleeve 12 is narrow, and the ring-shaped member 5
The clearance between a, 5b, 5c and the sleeve 12 is set so as to be narrow at the temperature at the time of pressure molding. Using this mold, an optical glass was molded according to the method described in Example 1. Glass material is 10
The coefficient of thermal expansion measured at 0 to 300 ° C. is 89 × 10 ⁻⁷ / ° C.
Was used. The capacity of the glass material was set to such an amount that the peripheral portion 11 of the glass material did not contact the inner end portion 10 of the ring-shaped member at the time of pressure molding. For this reason, cooling could be performed without the glass molded body being fastened to the ring-shaped member and with the upper and lower surfaces thereof being in contact with the molding surfaces of the respective molds. As a result, an optical glass having higher surface accuracy than in the case of Example 1 was stably manufactured.

Embodiment 5 FIG. 4A is a cross-sectional view of still another molding die of the present invention into which glass materials 1a to 1e have been introduced. This molding die is used for pressure-molding a flat product with a diffraction grating having a fine uneven surface pattern (outer diameter 64 mm, center thickness 1 mm). The molding die includes an upper die 2, intermediate dies 3a to 3d, a lower die 4, and a ring-shaped member (die interval determining means).
5a to 5e, an upper support 13, a lower support 14, and four cylinders 15. Among them, molds 2, 3a to 3d,
4. The material of the supports 13 and 14 is silicon carbide prepared by the CVD method. 5 is formed by first polishing a flat surface, applying a resist, transferring a fine pattern to the resist by a contact exposure method using a photomask, and forming a groove width of 1 to several μm by a reactive ion etching method. , Groove depth 0.2 ~
This was performed by forming a pattern of 0.3 μm (resist was removed) and forming a hard carbon thin film as a surface layer.
Four holes are formed in the outer peripheral portion of each mold and the mold support, and a cemented carbide column 15 penetrates these holes. This prevents axial displacement and displacement between the upper and lower molding surfaces. Further, ring-shaped members 5a to 5e for determining the thickness of the molded product and preventing the upper and lower surfaces of the molded product from being inclined are inserted into each column 15. FIG. 6 shows an example of the ring-shaped member. The material of the ring-shaped members 5a to 5e is stainless steel having a thermal expansion coefficient of 180 × 10 ⁻⁷ / ° C.].

A glass product with a fine pattern was prepared using a flat glass material having a mirror surface. First, the cylinder 15 is inserted into the lower support 13 and fitted therein, and the dies 2, 3a to 4d, the ring-shaped members 5a to 5e, and the coefficient of thermal expansion 89 × 10 ^−7.
/ ° C glass materials 1a to 1e are alternately stacked and FIG.
The structure shown in (a) was assembled. The flat glass material was arranged so that the glass material did not contact the inner end portion 10 of the ring-shaped member during pressure molding. This operation can also be performed by mechanically introducing a glass material with a gap between the molds, and mechanically positioning the introduced glass material from the outside so that the introduced glass material is positioned at the center of the mold. In this state, it was set in a molding machine and molded under pressure at 640 ° C. under vacuum. By the pressing for about 1 minute, the intermediate mold and the upper mold contacted the upper flat surface of each ring-shaped member, and the wall thickness was determined. The elongation before this thickness was determined was about 50 μm. As a result of repeating this molding, it was confirmed that the obtained molded article had no gas trap because it was pressurized in a vacuum state. Further, the transferability of the fine pattern was extremely good, and all necessary quality performances including the thickness were good. Further, prevention of lateral displacement and rotation was sufficient.

[0023]

According to the molding die and the molding method of the present invention, it is possible to prevent the upper and lower molding surfaces from being displaced due to the inclination of the intermediate mold and to prevent the shape of the molded product from being varied depending on the molding location. Therefore, according to the present invention, it is possible to stably manufacture a large number of molded articles having a uniform shape.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold according to the present invention described in Example 1.

FIG. 2 is a cross-sectional view of the mold of the present invention described in Example 3.

FIG. 3 is a sectional view of a mold according to the present invention described in Example 4.

FIG. 4 is a cross-sectional view of a mold according to the present invention described in Example 5.

FIG. 5 is an enlarged sectional view of a molding surface of a molding die of the present invention described in Example 5.

FIG. 6 is a plan view of a molding die of the present invention equipped with the ring-shaped member described in Example 5.

[Explanation of symbols]

1: Material for molding 2: Upper mold 3: Intermediate mold 4: Lower mold
5: Ring-shaped member 6: Forming surface 7, 8, 9: Flat portion 10: Inner end of ring-shaped member 11: Peripheral portion of molded product 12: Sleeve 13: Upper support 1
4: Lower support 15: Column

Claims (11)

[Claims] 1. A mold having an upper mold having a molding surface on a lower surface, a lower mold having a molding surface on an upper surface, at least one intermediate mold having molding surfaces on both upper and lower surfaces, and a mold having a mold interval determining means. 2. The molding die according to claim 1, wherein the mold interval determining means is a member located between outer edges of two adjacent dies. 3. The molding die according to claim 1, further comprising a die sliding guide means. 4. The molding die according to claim 3, wherein the mold interval determining means is fixed to an inner surface of the mold sliding guide means. 5. The molding die according to claim 1, further comprising means for preventing lateral displacement of the molding die. 6. The molding die according to claim 1, wherein a coefficient of thermal expansion of the mold interval determining means is larger than a coefficient of thermal expansion of the molding material. 7. The molding die according to claim 1, wherein the molding surface has a mirror surface or a fine pattern. 8. A molding material heated and softened in advance or a molding material is introduced between opposed molding surfaces of two adjacent molds of the molding die according to any one of claims 1 to 7. Heating and softening; pressing the upper mold, the lower mold or both of them to set each mold interval to the interval set by the mold interval determining means, and press-cooling the molding material. And a molding method. 9. The molding material is a glass material.
Molding method. 10. The molding method according to claim 8, wherein the volume of the molding material to be introduced is such that part or all of the outer peripheral portion of the molded body does not come into contact with the mold interval determining means during pressure molding. 11. The molding method according to claim 8, wherein the molding material is molded under pressure under reduced pressure.