JP3164410B2 - Body mold for molding optical elements - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus for press-molding a heat-softened optical material with a pair of upper and lower molding dies.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 62-56326 discloses a document as a member for conveying an optical material used in a conventional optical element molding apparatus. The technical content described in this publication is to provide a fitting part for fitting with a pair of upper and lower molding dies on a molding die, and to fit a fitting part of a pair of upper and lower molding dies to this fitting part of the trunk. An optical element molding apparatus and a method for molding while fitting are described. This apparatus is an effective technique when an optical element including an aspherical surface is molded without being decentered.

[0003] However, in the barrel mold described in the above publication, since the entire apparatus is integrally formed of the same material, the coefficient of linear expansion of the barrel mold is, for example, WC (6.6 × 10 ^-6 mm / ° C). When a small material such as is used, for example, the inner diameter of the barrel when an optical material (7.8 × 10 ⁻⁶ mm / ° C.) is placed and heated to 520 ° C., and the optical element after molding If the outer diameter is 5 mm, the clearance between the barrel and the optical element after cooling to 20 ° C. is extremely small, 0.0015 mm, and it is difficult to remove the optical element from the barrel.

On the other hand, when a material having a large linear expansion coefficient such as a SUS material (18 × 10 ⁻⁶ mm / ° C.) is used, the inner diameter of the drum changes greatly each time heating and cooling are performed. . 20mm to 520 ° C with a 5mm inner diameter body made of SUS material
, The inner diameter becomes 5.045 mm. The molded optical element has an outer diameter equal to the inner diameter of the barrel, but when cooled, the shrinkage is smaller than that of the SUS material, so that the optical element cannot be taken out of the barrel because it fits tightly. If the optical element is taken out, the optical element may be damaged, resulting in a defective product.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in such a manner that the optical material to be molded and the members constituting the body mold have different linear expansion coefficients, and the By forming a gap corresponding to the coefficient of linear expansion, the optical material can be molded without eccentricity even during molding, and easily removed without causing damage to the molded optical element even after mold release after cooling It is an object of the present invention to provide a mold for molding an optical element that can be used.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a body mold used for molding an optical element for press-molding a heat-softened glass material between a pair of upper and lower molds, wherein the body mold is at least one of the molds. With a fitting part with
An optical element holding member having a holding surface for an optical element, and a body-shaped outer member having an inner peripheral surface in contact with an outer peripheral surface of the optical element holding member, wherein the linear expansion coefficient of the body-shaped outer member is the above-described optical element The linear expansion coefficient of the optical element holding member is smaller than the linear expansion coefficient of the optical material, and the inner peripheral surface of the optical element holding member and the outer peripheral surface of the optical material have a clearance at room temperature. Further, it is a barrel mold for molding an optical element that is closely fitted when heated.

[0007]

Embodiment 1 A specific example of a barrel for molding an optical element according to the present invention will be described with reference to the drawings. 1 to 6 are action diagrams of respective steps showing a molding step of an optical element using the barrel for molding an optical element of the present invention. FIG. 1 is a cross-sectional view from the front showing a state at normal temperature in which an optical material is placed in a body-shaped outer member and an optical element holding member. FIG. 2 is a sectional view from the front showing a heating state following FIG. FIG. 3 is a sectional view from the front showing a heating state following FIG. FIG. 4 is a cross-sectional view from the front showing a step following FIG. 3 and showing a state of being molded by upper and lower molds. FIG. 5 is a cross-sectional view from the front showing a step following FIG. 4 and showing a state of a cooling step after molding is completed. FIG. 6 is a cross-sectional view from the front showing a step following FIG. 5 and showing a state at normal temperature after cooling the optical element.

Reference numeral 1 shown in FIG. 1 denotes a glass material SF11 (a linear expansion coefficient of 7.8 × 10 ⁻⁶ mm) having a formed surface polished in advance.
/ ° C) is an optical material molded into a circular shape. An optical element holding member 2 formed of a material made of SUS310S (linear expansion coefficient: 18 × 10 ⁻⁶ mm / ° C.) and having a donut shape is provided with the optical material 1 inserted and mounted in the inner diameter. The optical element holding member 2 is dimensioned so that the edge of the lower end surface of the optical element 1 can be mounted on the upper surface of the step portion 15 formed on the inner peripheral edge of the donut-shaped lower end portion in the inner diameter direction (axial direction). Is formed. The upper end opening of the optical element holding member 2 is formed with a body fitting part 8 having a shape corresponding to the insertion and removal of the upper mold fitting part 10 formed on the outer periphery of the upper mold 6 as shown in FIG. Have been.

A desired space (clearance) is provided on the outer peripheral surface of the above-mentioned optical element holding member 2, and a plate made of a material made of cemented carbide (linear expansion coefficient 6.6 × 10 ^-6 mm / ° C.) is used. A body-shaped outer member 3 formed in a shape is fitted and fitted. That is, a dimension in which the lower end surface of the optical element holding member 2 can be mounted on the upper surface of the flange-shaped step 16 formed in the inner diameter direction (axial direction) at a position near the lower end of the inner diameter of the body type outer member 3. Is formed. The inner diameter of the step 16 has a lower die 7 described later.
Is formed to have dimensions allowing insertion and removal, and further provided with a trunk receiving portion 12 formed by bending a protruding inner peripheral end portion upward. The step 15 of the optical element holding member 2 facing the inner diameter of the bent-shaped body receiving portion 12
Desired clearance (clearance) 1
7 are configured. In addition, the step portion 1 of the body type outer member 3
The lower end surface side of the body 6 has a body-shaped fitting formed so as to fit and slide with the lower mold fitted portion 11 provided on the outer periphery of the lower mold 7 as shown in FIG. A part 9 is formed.
Further, an engaging portion 18 is formed on the outer peripheral surface of the upper end portion of the body-shaped outer member 3 so as to engage with the transfer arm 4 (shown in FIG. 4) which is formed in a flange shape.

In the present embodiment, the optical element holding member 2 and the barrel-shaped outer member 3 are collectively referred to as a barrel-shaped body for convenience. The values required to be described in the present embodiment are as follows.

D ₁ Body type outer member at room temperature (3) Inner diameter d ₂ Optical element holding member at room temperature (2) Outside diameter d ₃ Optical material outer diameter at room temperature d ₄ Optical element holding member at room temperature (3) Inner diameter α ₁ Optical material linear expansion coefficient α ₂ Optical element holding member (2) Linear expansion coefficient α ₃ Body type outer member (3) Linear expansion coefficient t _O room temperature (20 ° C.) t ₁ Optical material temperature at steady heating t ₂ Body at steady heating Mold temperature

A process for forming an optical element using the above-described barrel for molding will be described with reference to the drawings. FIG. 1 shows a state at normal temperature, in which a desired gap (clearance) is formed between the optical material 1 and the optical element holding member 2 and between the optical element holding member 2 and the body type outer member 3. It is in a state. That is, utilizing the linear expansion coefficients of the body-type outer member 3 and the optical element holding member 2, d ₁ and d ₁
Decide ₂ . A ₁ in this case is white tightening the barrel type outer member 3 and the optical element holding member 2 at the time of the heating furnace.

[0013]

(Equation 1)

As described above, the position of the barrel type outer member 3 with respect to the optical element holding member 2 is determined. Then, remembering clearance A ₂ to room temperature during the optical element holding member 2 and the optical element 1 in this state, and after molding, as impart a clearance A ₃ on the optical element holding member 2 and the optical element 5 at room temperature, Using the following equation 2, d ₃ and d ₄ at normal temperature are determined. The clearances A ₂ and A ₃ are desirably 0.01 mm or more.

[0015]

(Equation 2)

In the above arrangement, the heating step shown in FIG. 2 starts. In this state, since the linear expansion coefficient of the optical element holding member 2 is larger than that of the body-shaped outer member 3, the outer diameter expands in the direction indicated by the arrow and the gap (clearance) provided between the optical element holding member 2 and the body-shaped outer member 3. However, the outer diameter cannot be further expanded due to the restriction on the inner peripheral surface of the body-shaped outer member 3.

Further, by continuing to heat the optical material 1 and the barrel molds 2 and 3, the state shown in FIG. 3 is obtained. That is,
The optical element holding member 2 that cannot be expanded outward as indicated by the arrow in FIG. 3 expands (bold arrow) toward the inner peripheral surface side. This expansion eliminates the gap (clearance) provided between the optical material 1 and the optical element holding member 2. Thereby, the optical material 1 is densely disposed at the center position of the body dies 2 and 3.

The barrel dies 2, 3 in which the optical materials 1 heated in the above steps are densely arranged are transported by a transport arm 4 between a pair of upper and lower molding dies 6, 7 shown in FIG. . That is, the optical material 1 placed on the shaft cores of the barrel dies 2 and 3 transported to the molding points by the transport arm 4 is configured to be driven vertically by a drive unit (not shown). By lowering the mold 6 and raising the lower mold 7, the body-type fitting portion 8 and the upper-type fitted portion 10 and the body-type fitting portion 9 and the lower-type fitted portion 11 fit and slide, respectively. After the upper and lower molds 6, 7 and the optical element 1 are aligned,
The optical material 1 is pressed by the molding surfaces formed on the respective end surfaces of the upper mold 6 and the lower mold 7 to press-mold the optical element 5.

The body dies 2, 3 formed by the above-described forming step
The inner optical element 5 is placed on the transfer arm 4 by raising and lowering the upper mold 6 and the lower mold 7 and is conveyed to the outside from between the molding dies 6 and 7 to be subjected to the next external cooling step. Moved
Cooled. FIG. 5 shows a state during cooling in the cooling step. As shown by the arrow in FIG. 5, the optical element holding member 2 has a larger shrinkage than the optical element 5 (bold arrow), so that a tight fit continues but the shrinkage ratio is small (fine arrow). The gap 17 between the body receiving portion 12 having the bent portion provided on the outer mold member 3 and the step portion 15 protruding in the inner diameter direction of the optical element holding member 2 abuts and disappears, and the optical element holding member 2 has the inner diameter. When the shrinkage decreases, the shrinkage of the outer diameter increases.

FIG. 6 shows a normal temperature state of the optical element 5, the optical element holding member 2, and the body-shaped outer member 3 cooled in the cooling step described above. That is, as shown by the arrow, the outer diameter of the optical element holding member 2 is shrunk (bold arrow), so that the optical element holding member 2 is not bundled with the inner diameter of the body type outer member 3. Due to this contraction, the inward expansion of the optical element holding member 2 shown in FIG. 3 is released, and the inner diameter increases. This is because the shrinkage of the body-shaped outer member 3 is larger than the shrinkage of the inner diameter of the optical element holding member 2 (arrows in a small character). Therefore, when the space between the optical element holding member 2 and the optical element 5 is heated to 520 ° C., if the dimensions shown in FIG.
m clearance occurs.

The optical element 5 is formed by the above-described forming steps shown in FIGS. Since the optical material 1 is molded after being positioned by the molding dies 6 and 7, the optical element 5 with less eccentricity can be molded. In addition, there is an advantage in quality such that the optical element 5 can be taken out without being damaged due to a difference in shrinkage after molding.

[0022]

[Embodiment 2] In this embodiment, a member having the same shape as that of Embodiment 1 is used, and the optical element 5 is molded in the same molding step. Therefore, in the present embodiment, the first embodiment is used.
The description will be made using the same drawings. N is applied to the optical element holding member 2.
Using an i-base heat-resistant alloy (linear expansion coefficient: 13.4 × 10 ⁻⁶ mm / ° C.), the body outer member 3 is made of Si ₃ N ₄ (linear expansion coefficient: 4 × 10 ⁻⁶ m).
m / ° C.) to mold the optical element 5. The above-mentioned material has higher heat resistance than the material used in Example 1 and is suitable for use at high temperatures. In the present embodiment, the optical element holding member 2 and the trunk outer member 3 made of materials other than the materials of the optical element holding member 2 and the trunk outer member 3 used in the first embodiment are used. In this case, by selecting a material such that the linear expansion coefficient satisfies the relationship of the barrel-shaped outer member <the optical element <the optical element holding member, the same operation and effect as in the first embodiment described above can be obtained.

[0023]

Third Embodiment A third embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a front sectional view showing the configuration of the barrel die according to the third embodiment of the barrel die for forming an optical element of the present invention and the state of the molding step. FIG. 8 is a sectional view from the front showing a positioning state of each member in a molding step following FIG. FIG. 9 is a sectional view from the front showing a molding state of a molding step following FIG. In the drawings, the same members, the same shapes, and the same configurations as those in the first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 7, the configuration of this embodiment different from that of the above-described first embodiment is different from that of the first embodiment in that the optical element holding member 20 for mounting and holding the optical material 1 and the body-shaped outer member 26 have different shapes and fits. In particular, the shape and configuration of the trunk-shaped receiving portion 27 are different in that the portions to be combined are different. That is, the optical element 1
Is placed at the center hole position, and a donut-shaped optical element holding a body-shaped fitting portion 25 for positioning with the upper die fitting portion 10 provided on the upper die at the opening above the hole. A cross-sectional shape is formed on the outer peripheral surface of the edge of the upper end portion 21 of the member 20 in an inverted L-shape, and the distal end portion 27 of the trunk type outer member 26 is formed on the lower end surface.
Are inserted, and a flange-shaped body receiving portion 22 having a groove 23 formed so as to be fitted with a desired clearance is formed.

On the outer peripheral surface of the optical element holding member 20 formed as described above, a donut-shaped body type outer member 26 is fitted and mounted with a desired gap (clearance). An outer peripheral surface of a distal end portion (upper end portion) 27 of the body-shaped outer member 26 has a flange near a base end of a portion to be inserted and fitted into the fitting groove 23 provided in the distal end portion 21 of the optical element holding member 20. A step 28 having a shape is formed. Further, a stepped portion 29 is formed on the peripheral surface of the lower end of the inner diameter of the body-shaped outer member 26 so as to protrude in the axial direction, and the lower end surface of the optical element holding member 20 is mounted on the upper surface thereof. It is configured. Further, the inner diameter of the body outer member 26 matches the inner diameter of the optical element holding member 20 and is configured to correspond to the outer diameter of the lower mold 7, and the lower mold is inserted and slid during molding to form an optical element. The material 1 can be formed. Further, the lower die 7 is positioned on the lower end surface and the peripheral surface (the trunk die fitting portion) 9 of the inner diameter step portion 29 of the trunk die outer member 26 in order to position the lower die 7. A torso-shaped fitting portion 9 formed to have a size corresponding to the fitting and sliding is provided.

Even in the case where the shape of the optical element holding member 20 on which the optical material 1 is placed is frequently changed, only the optical element holding member 20 is changed and the body-shaped outer member 26 is commonly used. it can.

Next, a description will be given of a molding process according to this embodiment having the above-described structure. FIG. 7 shows the state of the process in which the optical material 1 is placed at the center of the optical element holding member 20 housed in the barrel outer member 26 at normal temperature. Under the normal temperature condition, the optical material 1, the optical element holding member 20, and the barrel outer member 26 are heated in the next heating step shown in FIG.
Is expanded and is conveyed between the upper mold 6 and the lower mold 7, and the body mold outer member 26, the optical element holding member 20, and the optical material 1 are positioned by the lowering and rising of the upper mold 6 and the lower mold 7. ing. FIG. 9 shows a state at normal temperature when the optical material 1 is molded and cooled to become the optical element 5. The other steps are the same as those in the first embodiment, and the description is omitted. According to the present embodiment having the above configuration and process, even when the object to be molded such as the size of the optical material 1 is changed,
Since the molding setup can be performed by changing only the optical element holding member 20, remarkable advantages in terms of time and cost can be obtained.

[0028]

According to the present invention having the above configuration and operation,
Since the molding die is composed of at least two members having different linear expansion coefficients, and a clearance corresponding to the linear expansion coefficient of each member is formed between the optical element to be molded and each member, without decentering the optical element during molding. Can be molded. In addition, the molded optical element can be taken out without causing any damage to the molded optical element at the time of mold release after molding, so that an optical element excellent in quality, productivity and cost can be molded.

[Brief description of the drawings]

FIG. 1 relates to Embodiment 1 of a barrel for molding an optical element of the present invention, and relates to a room temperature during a molding process in which an optical material is placed in a barrel formed by a barrel outer member and an optical element holding member. It is sectional drawing from the front which shows the state at the time.

FIG. 2 is a front sectional view showing a heating state of each member during a heating step following the step of FIG. 1;

FIG. 3 is a cross-sectional view from the front showing a heating state of each member during a heating step following the step of FIG. 2;

4 is a cross-sectional view from the front showing a main part of a molding step following the step of FIG. 3, and showing a molding state of molding with upper and lower molding dies.

FIG. 5 is a cross-sectional view from the front showing a cooling state of each member during a cooling step following the step of FIG. 4;

FIG. 6 is a front sectional view showing the state of each member at normal temperature, following the process of FIG. 5;

FIG. 7 relates to Embodiment 3 of the barrel for molding an optical element of the present invention, at room temperature during a molding step in which an optical material is placed in a barrel composed of a barrel outer member and an optical element member. It is sectional drawing from the front which shows a state.

8 is a sectional view from the front showing a molding positioning state of each member on the molding die after the molding step of FIG. 7;

9 is a cross-sectional view from the front showing a state in which each member has reached a normal temperature through a cooling step after the forming step in FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical element 2, 20 Optical element holding member 3, 26 Trunk type outer member 4 Transfer arm 5 Optical element 6 Upper die 7 Lower die 8, 9, 25 Trunk type fitting part 10 Upper die fitting part 11 Lower die coating Fitting portion 12, 22 Trunk receiving portion 14 Projection 15, 16, 28, 29 Step 17 Clearance (gap) 18 Engaging portion 21 Upper end portion 23 Fitting groove 24 Lower end surface 27 Tip end (Top end)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-74724 (JP, A) JP-A-63-95130 (JP, A) JP-A-62-56326 (JP, A) 7137 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) C03B 11/08

Claims (1)

(57) [Claims] 1. A barrel mold used for molding an optical element for press-molding a heat-softened glass material between a pair of upper and lower molds, the barrel mold having a fitting portion with at least one of the molds and an optical element. An optical element holding member having an element holding surface, and a body-shaped outer member having an inner peripheral surface that is in contact with an outer peripheral surface of the optical element holding member, wherein the linear expansion coefficient of the body-shaped outer member is the optical element holding member. The linear expansion coefficient of the optical element holding member is smaller than the linear expansion coefficient of the optical element holding member, and the inner peripheral surface of the optical element holding member and the outer peripheral surface of the optical material have a clearance at room temperature. A mold for molding an optical element, wherein the mold is closely fitted when heated.