TW201335079A - Glass preform manufacturing method and glass preform, and optical device manufacturing method and optical device - Google Patents

Abstract

An upper mold (110) and a lower mold (130) are brought close to each other in a state where a lump of molten glass (YG) is floated on a molding surface (132) of the lower mold (130). A supply of gas to a gas ejection hole (133) is stopped until a molding surface of the upper mold (110) and the molding surface (132) of the lower mold (130) reach a press cutting position. In a state where the supply of the gas is stopped, the upper mold (110) and the lower mold (130) are brought closer to each other. The lump of molten glass (YG) is brought close to the molding surface (132) of the lower mold (130). In at least the press cutting position, press molding is performed to the extent that part of the lump of molten glass (YG) advances into the gas ejection hole (133) of the lower mold (130). By the glass preform (GP) manufacturing method, a glass preform (GP) having high reproducibility, low level variation and few wrinkles can be manufactured in a desired shape.

Description

Method for producing glass preform, glass preform, method for producing optical element, and optical element

The present invention relates to a method for producing a glass preform as a preform of an optical element (for example, an aspherical lens) and a glass preform, which is obtained by precision press molding to obtain an optical element (for example, an aspheric lens). A method of manufacturing an optical element and an optical element.

In the press molding, first, the raw materials (batch, glass shavings) of the glass are blended in a predetermined ratio, and the molten glass lump is supplied to the preform molding die through a melting, homogenizing, and clarifying step, thereby performing press forming, thereby obtaining and preforming. A glass preform having a shape corresponding to the shape of the molding surface of the body molding die. Next, the glass preform is supplied to a press molding die for precision press molding, whereby an optical element such as an aspherical lens is obtained.

As a manufacturing method of the glass preform, the manufacturing method disclosed by the patent document 1 (JP-A-2010-138052), the direct press method is known. In the direct pressing method, the molten glass flowing out from the outflow port of the outflow pipe is cut to obtain a molten glass lump, and the molten glass lump is supplied to the molding surface of the mold which is separated from the upper mold, and The molten glass piece is subjected to press molding between the upper mold and the lower mold to form a glass preform between the molding surfaces of the upper mold and the lower mold.

In the direct pressing method, when the molten glass lump is supplied to the molding surface of the mold which is lower than the molten glass lump, the portion of the molten glass lump which is in contact with the molding surface of the lower mold is sharply cooled due to the contact therebetween. The viscosity becomes higher. Therefore, after the glass preform is subjected to press molding, a difference in the temperature difference due to the molten glass lump and wrinkles occur in the boundary (neutral line) between the contact surface of the molten glass lump and the lower mold and the non-contact surface. The step and wrinkles of the glass preform are not completely eliminated in the subsequent step and remain on the optical surface of the optical element, so that the optical performance of the optical element is deteriorated and the yield is lowered.

In order to suppress the occurrence of the step and wrinkles of the glass preform, the method proposed in the patent document 2 (JP-A-2006-290702) is to form micropores for ejecting gas (upward gas) on the molding surface of the lower mold. The molten glass lump is supported in a non-contact manner, and in this state, the gas ejected from the molding surface of the upper die (pressurizing device) is blown onto the molten glass lump, thereby pressurizing the molten glass lump to obtain Glass preform.

However, since the molten glass lump is not in contact with the molding faces of the upper and lower dies at the time of pressurization, the shape of the molding surface cannot be accurately transferred on the glass preform, and a desired shape cannot be obtained, and the glass preform is not obtained. The shape deviation becomes large.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2010-138052

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-290702

The present invention has been made in view of the above problems, and an object thereof is to produce a glass preform having a reduced step and wrinkles in a desired shape with good reproducibility.

The present invention has been developed in view of the fact that the molten glass block is floated from a molding surface on which a plurality of gas ejection holes are formed, and the upper mold and the lower mold are brought close to each other to preheat the glass. When the molded body is subjected to press forming, the molten glass block and the lower portion can be stopped as long as the supply of the gas (upward gas) to the gas ejection hole is stopped until the molding surface of the upper mold and the molding surface of the lower mold are closest to the approaching position. The contact time of the molding surface of the mold is minimized to suppress the occurrence of the step and the wrinkles, and the shape of the molding surface of the molding die (the upper mold and the lower mold) is correctly transferred on the molten glass block, and the desired shape is obtained. The glass preform is produced with good reproducibility.

A method for producing a glass preform according to one aspect of the present invention is to use a molding surface having a facing shape and to be close to each other and to be separated from each other The mold and the lower mold have a plurality of gas ejection holes formed at least on the molding surface of the lower mold, and have a step of supplying a molten glass lump to the molding surface of the lower mold in a state where gas is ejected from the gas ejection holes of the lower mold. a step of supporting the molten glass block on the molding surface of the lower mold and supporting the upper mold and the lower mold in a state where the molten glass block is floated; when the molding surface of the upper mold and the molding surface of the lower mold reach an approach Before the position, stopping the supply of the gas to the gas ejection hole; and stopping the supply of the gas to the gas ejection hole, further bringing the upper mold and the lower mold into contact, and contacting the molten glass block with the molding surface of the lower mold; and at least In the approaching position, the step of press molding is performed to the extent that a part of the molten glass lump is allowed to enter in the gas ejection hole of the lower mold.

The press molding step can be carried out against the gas residual pressure in a state where the gas residual pressure is present after the supply of the gas to the gas ejection hole is stopped. Alternatively, the press molding step can be carried out in a state where the gas ejection from the gas ejection hole is completely stopped.

A glass preform according to one aspect of the present invention is produced by any one of the above-described methods for producing a glass preform, and a surface on a molding surface side of the mold under the glass preform is formed with a gas ejection hole. The convex part corresponding to the shape. Further, a concave portion formed by a curved surface is formed between adjacent convex portions.

A method of manufacturing an optical element according to one aspect of the present invention is The plurality of gas ejection holes are formed at least on the molding surface of the lower mold by using the opposite molding surfaces and capable of approaching and separating the upper mold and the lower mold, and having the following steps: discharging the gas from the gas ejection holes of the lower mold a step of supplying a molten glass lump to the molding surface of the lower mold, allowing the molten glass lump to float on the molding surface of the lower mold, and supporting the upper mold and the lower mold in a state where the molten glass lump is floated. The step of supplying gas to the gas ejection hole is stopped until the molding surface of the upper mold and the molding surface of the lower mold are closest to the approaching position; and the upper mold and the upper mold are further stopped while the gas supply to the gas ejection hole is stopped. a step of bringing the molten glass block into contact with the molding surface of the lower mold; at least in the approaching position, press forming a portion of the molten glass block in the gas ejection hole of the lower mold to obtain a molding in the lower mold a step of forming a glass preform having a convex portion corresponding to the shape of the gas ejection hole; and performing the finening of the obtained glass preform Press molding, an optical element and fine molding step after the disappearance of the protrusions was obtained.

The press molding step can be carried out against the gas residual pressure in a state where the gas residual pressure is present after the supply of the gas to the gas ejection hole is stopped. Alternatively, the press molding step can be carried out in a state where the gas ejection from the gas ejection hole is completely stopped.

An optical element according to an aspect of the present invention is the above A manufacturer of an optical component.

In the method for producing a glass preform according to one aspect of the present invention, the upper mold and the lower mold are adjacent to each other and have a facing surface, and at least a plurality of gas discharge holes are formed on the molding surface of the lower mold. The glass block is subjected to press molding to obtain a glass preform, and the glass preform is produced by supplying a molten glass block to a molding surface of the lower mold in a state where gas is ejected from a gas ejection hole of the lower mold. a step of supporting the molten glass block on the molding surface of the lower mold to support; after supplying the molten glass lump to the molding surface of the lower mold, stopping the supply of the gas to the gas ejection hole; and stopping the supply of the gas ejection hole In the state of the gas, the upper mold and the lower mold are brought close to each other, and the molten glass lump is brought into contact with the molding surface of the lower mold to perform press molding.

The step of stopping the supply of the gas is performed before the molding surface of the upper mold and the molding surface of the lower mold reach the approaching position.

The press forming step is performed at the approaching position.

A glass preform according to one aspect of the present invention is produced by any one of the methods for producing a glass preform, wherein the glass preform has a convex portion and a concave portion, and the convex portion and the concave portion are formed from the convex portion. The difference from the top to the bottom of the recess is below 20 μm.

The convex portion and the concave portion are formed to be the first difference from the top to the bottom of the convex portion formed at the central portion of the glass preform, and the second to the bottom portion of the convex portion formed by the peripheral portion of the glass preform The difference is greater.

According to the present invention, it is possible to produce a glass preform having a reduced step and wrinkles in a desired shape reproducibility.

100‧‧‧Glass preform molding

110‧‧‧上模

111‧‧‧Great Path Department

112‧‧‧Medium Department

113‧‧‧Little Trails Department

114‧‧‧ molding surface

120‧‧‧Upper model

121‧‧‧ Large diameter tubular

122‧‧‧Medium diameter tubular

123‧‧‧Small diameter tubular

124‧‧‧radial holes

130‧‧‧下模

131‧‧‧Annual section

132‧‧‧ molding surface

133‧‧‧ gas ejection holes (fine gas ejection holes, most holes)

140‧‧‧ Lower die support member

141‧‧‧The Great Trails Department

142‧‧‧Little Trails Department

143‧‧‧Cylinder space

144‧‧‧ lower end

150‧‧‧Down model

151‧‧‧ Large diameter tubular

152‧‧‧Small diameter tubular

153‧‧‧ upper end

160‧‧‧Precision press molding

161‧‧‧上模

161a‧‧‧ molding surface

162‧‧‧Down

162a‧‧‧ molding surface

163‧‧‧Model

170‧‧‧Rotary table

171‧‧‧arm

172‧‧‧Upper

200,230‧‧‧Glass preform manufacturing device

210‧‧‧Rotating table

220‧‧‧Combined body (forming die)

H‧‧‧ gas supply source

YG‧‧‧ molten glass block (softened glass block)

GP‧‧‧glass preforms

GT‧‧‧ convex

GR‧‧‧ recess

GTR‧‧‧ recess

Fig. 1 is a cross-sectional view showing the structure in which the upper mold and the lower mold of the preform molding die used in the method for producing a glass preform of the present invention are separated.

Fig. 2 is a cross-sectional view showing the structure of the upper mold and the lower mold of the preform molding die used in the method for producing a glass preform of the present invention.

Fig. 3 is a plan view showing the structure of a manufacturing apparatus of a rotary transfer type glass preform used in the method for producing a glass preform of the present invention.

Fig. 4 shows the steps of the method for producing a glass preform of the present invention. Fig. 4(A) shows the step of heating the lower mold by the halogen heater, and Fig. 4(B) shows the step of supplying the molten glass block from the feeder to the molding surface of the lower mold, and Fig. 4(C) shows The step of press-forming the glass preform by the molding surface of the upper mold and the lower mold, and the fourth (D) drawing shows the step of pressing the glass preform after press molding to make it cold, 4th ( E) shows the step of taking out the press-formed glass preform, and Figure 4(F) shows the lower mold after the glass preform is taken out. The steps to drop.

Fig. 5 is a view showing the microscopic phenomenon occurring in the molten glass lump in the press forming of the glass preform of Fig. 4(C). Fig. 5(A) shows a state before the molten glass lump is in contact with the molding surface of the lower mold, and Fig. 5(B) shows a state in which the molten glass lump is in contact with the molding surface of the lower mold.

Fig. 6 is a cross-sectional view showing the glass preform obtained by press molding in a state where the residual gas pressure from the gas ejection hole is present.

Fig. 7 is a cross-sectional view showing the glass preform obtained by press molding in a state where the gas ejection from the gas ejection hole is completely stopped.

Fig. 8 shows the construction of a precision press molding die.

Fig. 9 shows another embodiment in which a molten glass lump is cast into a molding die through another rotary table.

Fig. 10 shows a state in which the arm portion provided on the other rotating table is opened to supply the molten glass lump to the molding die.

Hereinafter, an embodiment of a method for producing a glass preform, a glass preform, a method for producing an optical element, and an optical element according to the present invention will be described with reference to the accompanying drawings. The vertical direction in the following description is based on the direction of the arrow line shown in the drawing.

"Method for producing glass preform and glass preform" (1) Construction of a glass preform molding die

Fig. 1 is a cross-sectional view showing the structure in which the upper mold and the lower mold of the preform molding die used in the method for producing a glass preform are separated. Fig. 2 is a cross-sectional view showing the structure in which the upper mold and the lower mold of the preform molding die used in the method for producing a glass preform are in close proximity. The glass preform molding die 100 includes an upper die 110, an upper die 120, a lower die 130, a lower die supporting member 140, and a lower die 150.

The upper mold 110 has, in order from the top, a large diameter portion 111, a smaller diameter inner diameter portion 112 than the large diameter portion 111, and a small diameter portion 113 having a smaller diameter than the intermediate diameter portion 112. A molding surface 114 (curvature radius R1) having a convex surface shape having a precise surface shape is formed on the lower surface of the small diameter portion 113. The upper mold 110 is made of, for example, a stainless steel (SUS) material having a release film.

The upper mold 120 is provided with a large-diameter cylindrical portion 121, a smaller-diameter cylindrical portion 122 having a smaller diameter than the large-diameter cylindrical portion 121, and a smaller diameter than the intermediate-diameter cylindrical portion 122. The tubular portion 123 is a tubular member that is open at both ends. The upper mold main shaft (not shown) is fixed to the through hole provided in the upper portion of the upper mold 110 in a state in which the lower end surface of the large diameter portion 111 of the upper mold 110 is brought into contact with the upper end surface of the small-diameter cylindrical portion 123. The upper mold main shaft and the upper mold dies 120 are integrated. The combination of the upper mold 110 and the upper mold 120 can be moved up and down in the vertical direction by an upper mold lifting mechanism (not shown).

In the lower mold 130, an annular segment portion 131 is formed in an intermediate portion of the outer peripheral surface, and a molding surface 132 (curvature radius R2) having a concave shape of a precise surface shape is formed on the lower surface. The radius of curvature R2 of the molding surface 132 of the lower mold 130 is formed to be smaller than the radius of curvature R1 of the molding surface 114 of the upper mold 110 (R1>R2). In the lower mold 130, along the molding surface of the lower mold 130 The concave shape of 132 is concentrically and regularly formed with a plurality of (many) gas ejection holes (fine gas ejection holes, a plurality of holes) 133 extending in the vertical direction (see FIG. 5).

The lower die supporting member 140 has a large diameter portion 141 and a small diameter portion 142 having a smaller diameter than the large diameter portion 141, and is a cylindrical member that forms a cylindrical space 143 that penetrates the vertical direction. The annular segment portion 131 is engaged with the upper end surface of the large diameter portion 141, and the lower mold 130 is supported by the lower die supporting member 140 to integrate the two. In the cylindrical space 143 in the lower die supporting member 140, only the vicinity of the upper end surface of the large diameter portion 141 is larger than the other portions, and most of the gas ejection holes 133 of the lower mold 130 are exposed in the cylindrical space 143. On the lower end side of the lower die supporting member 140, a gas supply source H for supplying a gas (inert gas) such as nitrogen gas (N ₂ gas) is connected. When the gas is supplied from the lower end surface side to the inside of the cylindrical space 143 of the lower mold supporting member 140 through the gas supply source H, the floating gas rises in the cylindrical space 143 of the lower mold supporting member 140, and enters. The gas ejection holes 133 of the lower mold 130 are supported by the upper end surface of the lower mold supporting member 140, and are ejected from the molding surface 132. That is, the cylindrical space 143 of the lower mold supporting member 140 serves as a gas flow path for the floating gas supplied from the gas supply source H.

The lower mold dies 150 have a large-diameter cylindrical portion 151 which is fitted to the outer peripheral surface of the large-diameter portion 141 of the lower mold 130 and the lower mold supporting member 140 with a clearance of a predetermined amount (for example, 200 μm). The outer peripheral surface of the small-diameter portion 142 of the lower die supporting member 140 is fitted with a small-diameter cylindrical portion 152 having a clearance of a predetermined amount (for example, 200 μm). Lower die 130 and lower die The combination of the support members 140 can be raised and lowered in the vertical direction in the cylindrical space 143 of the lower mold 150 by a lower mold lifting mechanism (not shown). Here, the position at which the lower mold 130 slightly protrudes from the upper end surface 153 of the lower mold dies 150 is the rising end of the lower mold 130 (refer to FIG. 4(A)), and the large-diameter cylindrical portion 141 of the lower mold supporting member 140. The lower end surface 144 abuts against the upper end surface 154 of the small-diameter cylindrical portion 152 of the lower mold dies 150 as the lower end of the lower mold 130.

(2) Construction of a manufacturing apparatus of a glass preform

Fig. 3 is a plan view showing the structure of a manufacturing apparatus 200 for a rotary transfer type glass preform. The glass preform manufacturing apparatus 200 has 12 treatment positions 1-12 arranged at intervals of 30° in the circumferential direction. In the manufacturing apparatus 200 of the glass preform, a rotary table 210 (intermittent indexing device) is provided, and the member on the lower mold side 130 of the glass preform molding die 100 is placed on the rotary table 210 (lower die 130 and lower die support) A combination of the member 140 and the lower mold dies 150, hereinafter also referred to as a molding die 220). The rotary table 210 is intermittently rotated counterclockwise by 30° every predetermined time by a drive source (not shown), whereby the molding die 220 placed on the rotary table 210 is sequentially transferred to the respective treatment positions 1-12. In other words, the manufacturing apparatus 200 for a glass preform of the present embodiment can simultaneously accommodate members (molding molds 220) on the lower mold 130 side of the glass mold preforms 100 of the twelve groups. On the other hand, at the treatment position 3 of the manufacturing apparatus 200 of the glass preform, the member on the upper mold 110 side of the glass preform molding die 100 (the combination of the upper mold 110 and the upper mold 120) is disposed.

(3) Method for producing glass preform

In addition to the above-described first to third figures, reference is made to the steps of the fourth (A) to the fourth (F) and the fifth (A) to the fifth (B), and the glass of the present embodiment is used. The manufacturing method of the preform is explained in detail. Fig. 4 shows the steps of a method of manufacturing a glass preform. Figure 4(A) shows the step of heating the lower mold by a halogen heater, and Figure 4(B) shows the step of supplying the molten glass block from the feeder to the molding surface of the lower mold, Fig. 4(C) The step of performing press forming of the glass preform by the molding surface of the upper mold and the lower mold is shown, and the fourth (D) drawing shows the step of performing the cold cooling by pressing the formed glass preform upward, and the fourth step (4) E) shows the step of taking out the press-formed glass preform, and Figure 4(F) shows the step of lowering the lower mold after the glass preform is taken out.

The method for manufacturing the glass preform of the present embodiment is carried out by preparing a molding surface 114 and a molding surface 132 which are opposed to each other and which can approach or separate the upper mold 110 and the lower mold 130 from each other, at least in the molding of the lower mold 130. The face 132 is formed with a plurality of gas ejection holes 133.

First, at the treatment position 1, as shown in Fig. 4(A), the lower mold 130 is raised to the rising end by a lower mold elevating mechanism (not shown), and the lower mold 130 is heated by a halogen heater. The heating temperature of the mold 130 heated by the halogen heater is, for example, 240 °C. The lower mold 130 after the end of the heating is lowered to the lower end by the lower mold lifting mechanism, and then the rotation of the rotary table 210 is transferred to the disposal position 2.

Next, at the treatment position 2, as shown in Fig. 4(B), the lower mold 130 is raised to a position slightly higher than the rising end by a lower mold lifting mechanism (not shown). At the lower pouring position, a molten glass lump (softened glass block) YG is supplied from the position directly above the molding surface 132 of the lower mold 130 by a feeder. Here, the lower end portion (front end portion) of the molten glass flow is received by the molding surface 132 of the lower mold 130. When the molten glass flows out in a predetermined amount, the lower mold 130 is sharply lowered by the lower mold lifting mechanism to cut the molten glass. The molten glass lump YG is supplied to the molding surface 132 (down-cut method). The temperature of the molten glass block YG supplied is, for example, equivalent to a temperature of 1 to 20 poise of glass viscosity. At this time, on the molding surface 132 of the lower mold 130, the floating gas supplied from the gas supply source H is ejected through the gas ejection hole 133 (gas flow rate at the time of pouring and floating: 0.20 L/min), when the lower end portion of the molten glass flow The molten glass which is received by the molding surface 132 of the lower mold 130 and the molten glass lump YG supplied on the molding surface 132 are supported on the molding surface 132 of the lower mold 130 in a floating state. That is, the floating gas is interposed between the lower end portion of the molten glass or the molten glass block YG and the molding surface 132 of the lower mold 130. In this step, the molten glass block YG is supplied onto the molding surface 132 of the lower mold 130 in a state where the floating gas is ejected from the gas ejection hole 133 of the lower mold 130, and the molten glass block YG is floated on the molding surface 132 of the lower mold 130. The step of supporting. Then, the rotary table 210 is rotated by 30°, and the lower mold 130 and the molten glass lump YG are transferred to the disposal position 3. When the glass preform GP is molded from the molten glass, the molten glass and the molten glass block YG supplied to the molding surface 132 of the lower mold 130 may be in instantaneous contact with the molding surface 132 of the lower mold 130. In the present specification, The molten glass and the molten glass lump YG are expressed by the contact of the lower mold 130 in a range where no fusion occurs, so that it is supported by floating or supported.

Next, at the treatment position 3, as shown in Fig. 4(C), the molding surface 132 of the lower mold 130 is lowered from the upper end surface 153 of the lower mold 150 by a predetermined amount, and the upper mold lifting mechanism (not shown) is used. The upper mold 110 is lowered. This step is a step of bringing the upper mold 110 and the lower mold 130 close to each other in a state where the molten glass lump YG is floated. At this time, the outer peripheral surface of the small-diameter portion 113 of the upper mold 110 is lowered so as not to contact the inner peripheral surface of the large-diameter cylindrical portion 151 of the lower mold dies 150. Then, the servo motor (not shown) is driven, and the molding surface 132 of the upper mold 110 is brought close to the molding surface 132 of the upper mold 110 to press the molten glass block YG, whereby the glass preform GP is press-formed. At the time of press molding, the position at which the upper mold 110 and the lower mold 130 are closest is represented by an approaching position which can be determined in consideration of the shape, thickness, and the like of the glass preform GP to be produced. In addition, the viscosity of the molten glass block YG at the time of press molding is set to, for example, 20 dPa. s~300dPa. s or so. Here, although the upper mold 110 and the lower mold 130 are brought close to each other, the lower mold 130 is lifted by the servo motor to press-form the glass preform GP, but it is also possible to obtain the upper mold 110 and the lower mold. The approach position of 130 causes the upper mold 110 to further descend to press-form the glass preform GP. Further, in press molding, it is preferable to increase the shape accuracy of the glass preform GP at the approaching position, but the upper mold 110 and the lower mold 130 are brought close to each other before reaching the approach position.

Here, the microscopic phenomenon of the molten glass lump YG in press molding of the glass preform GP will be described with reference to FIGS. 5(A) to 5(B). Fig. 5 is a view showing a microscopic phenomenon of a molten glass lump in press forming of the glass preform of Fig. 4(C). Fig. 5(A) shows a state before the molten glass lump is in contact with the molding surface of the lower mold, and Fig. 5(B) shows a state in which the molten glass lump is in contact with the molding surface of the lower mold. Further, in the fifth (A) to fifth (B) drawings, in order to make the content of the present invention easier to understand, the aperture and pitch of the gas ejection hole 133 are drawn more exaggerated than the actual situation.

When the upper mold 110 and the lower mold 130 are brought close to each other in a state where the molten glass lump YG is floated, first, as shown in Fig. 5(A), the upper surface of the molten glass lump YG is in contact with the molding surface 114 of the upper mold 110. On the other hand, the lower surface of the molten glass lump YG is ejected from the gas ejection hole 133 of the lower mold 130 without being in contact with the molding surface 132 of the lower mold 130, and the gas which has not entered the lower mold 130 by the molten glass lump YG is ejected. The molten glass lump YG is press-formed in the state inside the hole 133. The press molding at this time is different from the press molding described in the next paragraph, and the molten glass block YG is brought close to the molding surface of the upper mold 110 by bringing the molding surface 114 of the upper mold 110 into contact with the upper side of the molten glass lump YG. The shape of the 114-face shape is deformed, and the surface shape of the molding surface 114 of the upper mold 110 is transferred to the molten glass lump YG, and the lower surface of the molten glass lump YG and the molding surface 132 of the lower mold 130 are maintained in a non-contact state, and the floating surface is maintained. The gas is deformed in such a manner as to be close to the surface shape of the molding surface 132 of the lower mold 130.

In the present embodiment, the step of supplying the floating gas from the gas supply source H to the gas ejection hole 133 is stopped until the approaching position at which the molding surface 114 of the upper mold 110 and the molding surface 132 of the lower mold 130 are closest to each other is reached. When the step of stopping the supply of the floating gas is performed, for example, the upper mold 110 and the lower mold 130 are connected before the upper mold 110 and the lower mold 130 are brought close to each other. When the molding surface 112 of the upper mold 110 is brought into contact with the molten glass lump YG (at the start of the press molding described above), or the upper mold 110 and the lower mold 130 are further brought to the press molding. Here, as an example of the present embodiment, a case where the upper mold 110 and the lower mold 130 are brought close to each other and the supply of the floating gas is stopped during the press molding will be described.

When the supply of the floating gas to the gas ejection hole 133 is stopped in the above press molding, the molding surface 114 of the upper mold 110 is brought into contact with the molten glass YG in a state where the residual pressure of the floating gas from the gas ejection hole 133 exists, until the lower mold When the molding surface 132 of 130 is in contact with the molten glass YG, the outer diameter of the molten glass YG can be enlarged. At this time, the outer diameter of the molten glass YG may be equal to or smaller than the inner diameter of the large-diameter cylindrical portion 151 of the lower mold dies 150. If the upper mold 110 and the lower mold 130 are further brought closer in the state where the residual residual pressure of the floating gas is present, as shown in Fig. 5(B), a lower portion of the molten glass lump YG and the molding surface 132 of the lower mold 130 are formed. contact. In this step, in a state where the supply of the floating gas to the gas ejection hole 133 is stopped, the upper mold 110 and the lower mold 130 are further brought closer, and the molten glass block YG is brought into contact with the molding surface 132 of the lower mold 130.

In the present embodiment, as a final step, the molding surface 114 of the upper mold 110 and the molding surface 132 of the lower mold 130 are closest to each other, so that a part of the molten glass block YG is allowed to be in the gas ejection hole 133 of the lower mold 130 ( The step of press forming is performed to the extent that the portion not in contact with the molding surface 132 of the lower mold 130 enters. Thereby, the molten glass lump YG can be subjected to press molding to obtain a glass preform GP. At this time, the outer peripheral surface of the glass preform GP is restricted by the inner peripheral surface of the lower mold dies 150, and It is the desired size (the same diameter as the inner peripheral surface of the lower mold 150). Further, in the present embodiment, since the supply of the floating gas is stopped before the upper mold 110 and the lower mold 130 reach the approaching position, the molten glass lump YG can be floated for as long as possible. In this way, the step and wrinkles of the glass preform can be suppressed. Further, after the supply of the floating gas is stopped, the molten glass lump YG can be press-formed in a state of being in contact with the molding surface 132 of the lower mold 130, and the molding surface 132 of the lower mold 130 can be sucked from the molten glass block YG in press molding. By taking enough heat, a glass preform having a high shape accuracy (small step and wrinkle (shallow)) can be obtained. This is because, after supplying the molten glass lump YG, the molten glass lump YG is floated for as long as possible (in other words, until press molding), whereby the contact time of the molten glass lump YG and the molding surface 132 of the lower mold 130 can be made. shorten.

In the glass preform GP thus press-molded, a minute convex portion GT corresponding to the shape of the gas ejection hole 133 is formed on the surface of the molding surface 132 of the lower mold 130. That is, the press forming step as the final step is at least the approaching position of the molding surface 114 of the upper mold 110 and the molding surface 132 of the lower mold 130 so as to allow the molten glass block in the gas ejection hole 133 of the lower mold 130. A part of the YG (a portion that is not in contact with the molding surface 132 of the lower mold 130) is subjected to press molding, whereby a convex portion corresponding to the shape of the gas ejection hole 133 is formed on the surface of the molding surface 132 side of the lower mold 130. GT glass preform GP. Further, a minute recess GR formed by a curved surface is formed between the adjacent convex portions GT. The concave portion GR is a contact surface between the molding surface 132 of the lower mold 130 and the molten glass YG at the time of press molding, due to the temperature drop of the molten glass YG It is formed by shrinking the molten glass YG.

At this time, attention is paid to one of the molding faces 132 of the fifth (B) drawing, and more than the molten glass lump YG which is in contact with the central portion of the molding surface 132, compared with the molten glass lump YG which is in contact with both end portions of the molding surface 132. The heat is sucked away, so that more shrinkage occurs than the molten glass lump YG that is in contact with both end portions of the molding surface 132. Therefore, the concave portion GR is formed into a curved line (curved surface shape).

Next, attention is paid to one gas ejection hole 133 provided between the adjacent two molding faces 132 of the fifth (B) drawing. Among the molten glass lump YG in the one gas ejection hole 133 observed, the molten glass block YG entering the central portion of the gas ejection hole 133 has a resistance ratio higher than the end portion of the gas ejection hole 133 (the end of the molding surface 132). The molten glass block YG in the vicinity is small, and since it is not in contact with the molding surface 132 of the lower mold 130, it is not easily cooled, and the glass maintains a low-viscosity state and smoothly enters. Therefore, the entry distance (=the height of the mountain portion of the convex portion GT) into the gas ejection hole 133 of the molten glass lump YG entering the center portion of the gas ejection hole 133 is maximized. The inner ends of the adjacent two molding faces 132 are joined to each other by an imaginary straight line, which is the shortest distance from the straight line to the molten glass lump YG. On the other hand, among the molten glass lump YG entering the gas ejection hole 133 of the molding surface 132, the molten glass block YG which enters the end (periphery) of the gas ejection hole 133 is in contact with the end portion of the molding surface 132 of the lower mold 130. On the other hand, the glass is made to be highly viscous, so that the resistance is maximized and it is hard to enter the gas ejection hole 133. Further, from the molten glass block YG entering the central portion of the gas ejection hole 133 to the gas injection The molten glass block YG at the end of the exit hole 133 is formed with a smooth curve (curved surface) convex portion GT due to an increasing resistance at the time of entry. Further, the curve of the convex portion GT thus formed and the curve of the concave portion GR are connected to the end portion of the gas ejection hole 133. Therefore, the end portion of the gas ejection hole 133 of the lower mold 130 (the end portion of the molding surface 132) becomes an inflection point of the curve of the convex portion GT and the concave portion GR.

Based on this, the inventors of the present invention presume as follows. In the vicinity of the central portion of the molding surface 132, the molten glass lump YG shrinks the glass by the cooling effect generated by the contact with the lower mold 130, and the distance (depression depth) which is separated upward from the molding surface 132 becomes extremely large (extreme value). . On the other hand, in the vicinity of the center of the gas ejection hole 133, the cooling rate of the molten glass YG is the slowest and the low viscosity state is maintained, and the distance (the height of the mountain portion) from the molding surface 132 caused by the glass entering becomes extremely large. (extremum). Further, in the most peripheral portion of the gas ejection hole 133, the molding surface 132 is in contact with the glass, and the height between the two extreme values is obtained. Therefore, the inventors presume that the end portion of the gas ejection hole 133 of the lower mold 130 (molding surface 132) The end portion) becomes an inflection point of the curve of the convex portion GT and the concave portion GR.

Further, the position of the inflection point is an end portion (the end portion of the molding surface 132) of the gas ejection hole 133. However, the present invention is not limited thereto, and the gas ejection hole 133 of the lower mold 130 to be used depending on the molding conditions. The aperture or pitch may be offset by the position of the inflection point. Further, in the present embodiment, the case where the convex portion GT and the concave portion GR are connected by the inflection point is described, but the present invention is not limited thereto.

In the fifth (B) diagram, in order to facilitate understanding, the convex portion GT, The concave portion GR and the gas ejection hole 133 are enlarged. Actually, the convex portion GT, the concave portion GR, and the gas ejection hole 133 are formed to have a small diameter, and the concave shape along the molding surface 132 of the lower mold 130 is regularly (equal pitch) ) Configuration. The height of the mountain portion of the convex portion GT is the lowest in the vicinity of the center portion of the concave surface shape of the molding surface 132 of the lower mold 130, and tends to gradually increase toward the peripheral portion. This is based on the surface temperature distribution of the molten glass lump YG in press molding, which will be described below. That is, the lower surface of the molten glass lump YG is cooled by the floating gas from the time of pouring to the press forming, and therefore the glass which is in contact with the vicinity of the central portion of the concave shape of the molding surface 132 of the lower mold 130 becomes lower temperature at the start of press forming. That is, high viscosity. On the other hand, the glass which is in contact with the peripheral portion side of the concave shape of the molding surface 132 of the lower mold 130 is a glass which is supplied by extrusion from the inside of the molten glass lump Y in press molding, and is not cooled by the floating gas. The temperature is higher than the glass in contact with the vicinity of the center portion of the concave shape of the molding surface 132 of the lower mold 130, that is, it is low in viscosity. As described above, the height of the mountain portion of the convex portion GT is the lowest in the vicinity of the center portion of the concave surface shape of the molding surface 132 of the lower mold 130, and tends to gradually increase toward the peripheral portion. However, the difference in the height of the mountain portion of the convex portion GT, that is, the difference in the entering distance of the molten glass YG toward the gas ejection hole 133 of the lower mold 130, is the difference between the surface of the glass before pressing, or from the pressing. The difference in the surface regenerated by the glass floating on the surface of the molten glass YG is strictly changed discontinuously in the peripheral portion of the outer diameter of the molten glass lump YG before pressing.

Here, even after the supply of the floating gas from the gas supply source H toward the gas ejection hole 133 is stopped, the mold is branched under the gas flow path. The cylindrical floating space 143 of the receiving member 140 still has the supplied floating gas (there is residual pressure), so that the floating gas continues to be ejected from the gas ejection hole 133 for a predetermined period of time. The press molding of the fifth (B) diagram can be carried out in a state in which the discharge of the floating gas is continued, against the residual pressure of the floating gas, or in a state in which the discharge of the floating gas is completely stopped. In the former case, the molten glass block YG that has entered the gas ejection hole 133 can form a recess GTR, which will be described later, and can suppress the height of the convex portion GT (the amount of entry into the gas ejection hole 132). In the latter case, the convex portion GT and the concave portion GR can be connected by a smooth curve, and the glass preform GP having a step and a wrinkle can be formed. The press molding of Fig. 5(B) is carried out against the floating gas in a state where the discharge of the floating gas continues (the state in which the residual pressure exists), or in a state after the complete stop (the state without the residual pressure). Further, it is carried out in a state in which the amount of the floating gas is discharged, and can be appropriately set in accordance with the intended glass preform GP, the shape and performance of the optical element, and the like.

Fig. 6 is a cross-sectional view showing the glass preform GP obtained by press molding in a state where the residual gas pressure from the gas ejection hole is present. In other words, Fig. 6 shows a glass preform GP in which the press molding of Fig. 5(B) is carried out in a state where the discharge of the floating gas is continued, against the floating gas. On the lower surface side of the glass preform GP, a minute recess GTR is formed by the residual pressure of the floating gas at the tip end portion of each convex portion GT formed by the molding surface 132 of the lower mold 130. Further, it is formed on the upper surface side of the glass preform GP, which is similar to the radius of curvature R1 formed by the molding surface 114 of the upper mold 110, or has the same curvature. The curved surface formed by the radius R1 has a radius of curvature R1 on the upper surface side of the glass preform GP, and a radius of curvature R2 when the inflection point of each convex portion GT formed on the lower surface side of the glass preform GP is connected. Larger (R1>R2). Further, the press molding of the fifth (B) drawing is carried out against the floating gas in a state where the discharge of the floating gas is continued, and the step of the glass preform GP and the wrinkles can be suppressed regardless of the stop point of the gas supply. occur. At this time, the discharge amount and pressure of the floating gas are set in consideration of the height of the concave portion GTR and the convex portion GT formed in the glass preform.

Fig. 7 is a cross-sectional view showing the glass preform GP obtained by press molding in a state where the gas ejection from the gas ejection hole is completely stopped. That is, Fig. 7 shows a glass preform GP in which press molding of Fig. 5(B) is carried out without residual pressure. On the lower surface side of the glass preform GP, the tip end portion of each convex portion GT formed by the molding surface 132 of the lower mold 130 (see FIG. 5(B)) has a smooth curved shape. Further, the height of the unevenness of the glass preform GP is compared with the case where the press-molding of the fifth (B) diagram shown in Fig. 6 is carried out in the state where the discharge of the floating gas is continued, and the glass preform is carried out against the floating gas. The height of the bump of the body GP has a greater tendency. Further, a curved surface formed by the curvature radius R1 formed by the molding surface 114 of the upper mold 110 or a curved surface having the same curvature radius R1 is formed on the upper surface side of the glass preform GP. As described above, the radius of curvature R1 of the upper surface side of the glass preform GP is larger than the radius of curvature R2 when the inflection points of the convex portions GT formed on the lower surface side of the glass preform GP are connected (R1>). R2). In the description of Figures 6 and 7, it is explained R1>the aspect of R2, but the invention is not limited thereto. Further, the surfaces of both the upper side and the lower side of the glass preform GP may be formed in a convex shape.

After the press molding of the glass preform GP is completed, the upper mold 110 is raised by an upper mold elevating mechanism (not shown) to separate the upper mold 110 and the lower mold 130, and the gas supply source H is directed toward the gas after a predetermined period of time. The supply of the floating gas above the discharge hole 133 starts again. The "established time" here is a sufficient time from the completion of press molding to the time when the glass viscosity becomes desired viscosity. In this manner, the glass preform GP is detached from the molding surface 132 of the lower mold 130, and is supported on the molding surface 132 of the lower mold 130 in a non-contact floating manner. In this state, the rotary table 210 is rotated by a predetermined amount, and the glass preform GP and the lower mold 130 are transferred to the disposal position 4. Further, when the supply of the floating gas from the gas supply source H to the gas ejection hole 133 is started again, it can be set to any point after the completion of the press molding, and after the press molding is completed, it is transferred to the treatment position 4 (refer to Fig. 3). After that, the supply of the floating gas can be started again. When the supply of the floating gas is started again immediately after the press forming, it is preferable to adjust the gas flow rate to avoid deformation of the shape of the glass preform GP after molding.

At the disposal position 4, as shown in Fig. 4(D), the lower mold 130 is raised to the rising end by a lower mold elevating mechanism (not shown). At this time, the press-formed glass preform GP is ejected from the upper end surface 153 of the lower mold dies 150, and the contact between the lower mold dies 150 and the outer peripheral surface of the glass preform GP is terminated early, thereby preventing glass preforming. The outer peripheral surface of the body GP is excessively cooled. In this way, defects and cracks caused by a difference in cooling rate between the central portion and the outer peripheral surface of the glass preform GP can be suppressed. Then let The lower mold 130 is lowered, and a part of the outer peripheral surface of the glass preform GP is extended from the upper end of the large-diameter cylindrical portion 151 of the lower mold dies 150. In this state, the rotary table 210 is rotated to lower the lower mold 130 and the glass. The preform GP is transferred to the disposal site 5 and then sequentially transferred to the disposal site 6-10. By lowering the lower mold 130 from the ascending end, the outer peripheral surface of the glass preform GP is restricted by the inner peripheral surface of the large-diameter cylindrical portion 151 of the lower mold dies 150 at the time of transfer, and the glass preform GP is under The molding surface 132 of the mold 130 can be transferred while maintaining the position. At the disposal position 5-10, the press-formed glass preform GP is quenched. At this time, the gas ejection nozzle (not shown) disposed above the lower mold 130 can be placed at each treatment position to be quenched, and the position of the gas discharge nozzle disposed at each treatment position can be adjusted to obtain a predetermined cooling efficiency.

Here, although the example in which the lower mold 130 is lowered from the rising end is shown, the present invention is not limited thereto, and the lower mold 130 may be held at the rising end position to take out the glass preform GP, and the molding surface 132 may be formed on the molding surface 132. The positional deviation of the glass preform GP is prevented, for example, the lower mold 130 may be lowered by the processing position 8-10.

Next, at the disposal position 11, as shown in Fig. 4(E), the glass preform GP supported on the molding surface 132 of the lower mold 130 is supported by the suction pad having the suction function, and is moved to the surface of the lower mold 130. The exterior of the preform molding die 100 is taken out. Finally, at the disposal position 12, as shown in Fig. 4(F), the lower mold 130 is lowered to the lower end by a lower mold elevating mechanism (not shown).

As described above, the glass preform of the present embodiment is manufactured In the state in which the molten glass block YG is floated on the molding surface 132 of the lower mold 130, the upper mold 110 and the lower mold 130 are brought close to each other, and the molding surface 114 of the upper mold 110 and the molding surface 132 of the lower mold 130 reach the approaching position. Previously, the supply of the floating gas to the gas ejection hole 133 is stopped, and in the state where the supply of the floating gas to the gas ejection hole 133 is stopped, the upper mold 110 and the lower mold 130 are further brought closer, and the molding surface 132 of the molten glass block YG and the lower mold 130 is allowed. The contact is subjected to press molding to the extent that a part of the molten glass lump YG enters in the gas ejection hole 133 of the lower mold 130 at least in the approaching position. Thereby, the contact time between the molten glass lump YG and the molding surface 132 of the lower mold 130 is minimized, and the occurrence of the step and the wrinkles can be suppressed, and the glass preform GP having a desired shape can be reproducibly produced.

The method for producing a glass preform according to the present embodiment can be applied to all preforms such as a non-abrasive preform which is preformed into a flat shape (double convex curved shape), and is particularly suitable for production and optical elements as final products. Approximate shape preforms of similar shape. In the case of an approximately shape preform, it is necessary to form a glass material which is required to reduce the amount of deformation during precision press molding, and it is required to obtain a desired shape in the production stage of the glass preform. Further, it is also useful for the long life of the fusion preventing film formed on the precision press molding die and the precision press molding die caused by the reduction in the pressing temperature during precision press molding.

Further, in the case of a glass preform composed of a glass material which is easily fused with a molding die which is precisely press-molded, a coating for preventing fusion can be applied to the surface of the glass preform. However, when the amount of deformation (change rate) of the glass preform during precision press molding is large, When the coating is broken and the inner glass is poured out, the glass which is fused with the molding die causes defects in the surface of the precision pressed product, and an optical element having desired performance cannot be obtained. When glass fusion occurs on the surface of the molding die, the subsequent precision press molding becomes impossible. In view of this, in order to reduce the amount of deformation during precision press molding and to prevent cracking of the coating, it is required to obtain a desired shape in the production stage of the glass preform.

Then, in the method of producing the glass preform of the present embodiment, in the final stage of press molding, the molding surface 114 of the upper mold 110 is brought into contact with the upper surface of the molten glass block YG while the supply of the floating gas to the gas discharge hole 133 is stopped. The molding surface 132 of the lower mold 130 is brought into contact with the lower surface of the molten glass lump YG to perform press molding. In this way, an approximately shaped glass preform GP having a desired shape without stepping and wrinkle reduction can be produced. Further, since the amount of radial deformation of the glass preform GP at the time of precision press molding is small, the coating for preventing fusion of the glass preform GP is not damaged.

On the other hand, for example, in the above-mentioned Patent Document 2, since the molten glass lump is not in contact with the molding faces of the upper mold and the lower mold at the time of press molding, heat cannot be sucked away from the molten glass lump, and transfer on the glass preform cannot be performed. The shape of the molding surface does not limit the outer diameter of the glass preform, so that a desired shape cannot be obtained, and the shape deviation of the glass preform is large. Therefore, it is not suitable for manufacturing an approximately shape preform, and there is a problem that the coating for preventing fusion is broken during precision press molding.

"Method of manufacturing optical components and optical components"

The glass preform GP manufactured as described above is temporarily stored in a container such as a tray, and then supplied to a precision press molding mold through a predetermined step such as a washing step and a film forming step for preventing fusion.

Fig. 8 shows the structure of the precision press molding die 160 used in the present embodiment. The precision press molding die 160 is composed of an upper die 161, a lower die 162, and a die 163. The upper mold 161 and the lower mold 162 are formed of a small diameter portion and a large diameter portion larger than the diameter of the small diameter portion, and each of the small diameter portions includes a molding surface 161a having a convex surface shape having a precise surface shape and a concave surface. Shaped molding surface 162a. Further, the die 163 is formed in a cylindrical shape having both ends open.

The precision press molding die 160 is assembled as follows. First, the upper mold 161 is inserted inside the mold 163, and the lower surface of the large-diameter portion of the upper mold 161 is abutted on the upper surface of the small-diameter inner portion of the mold 163, whereby the upper mold 161 and the mold 163 are assembled in advance. . Next, in a state where the molding surface 162a of the lower mold 162 is opposed to the molding surface 161a of the upper mold 161, the lower mold 162 is inserted into the dies 163 from the lower side, and the upper mold 161, the lower mold 162, and the dies 163 are integrated. Chemical.

After the glass preform GP is supplied to the precision press molding die 160, precision press molding is performed by a press molding apparatus (not shown). In the following, a precision press molding method in which press molding and so-called isothermal press molding are performed by heating the precision press molding die 160 and the glass preform GP together. However, the precision press molding may be performed by separately preheating the precision press molding die 160 and the glass preform GP, and performing press molding, so-called non-isothermal press molding, and the method is not limited.

In the isothermal press molding, the precision press molding die 160 and the glass preform GP are first heated together to a temperature above the glass transition point (Tg) of the glass preform GP. Thus, the upper mold 161, the lower mold 162, and the glass preform GP are made isothermal to each other, and the glass viscosity of the glass preform GP is 10 ⁶ to 10 ¹² poise suitable for precision press molding. Further, it is more preferable to perform precision press molding by heating to a temperature of 10 ⁸ to 10 ¹¹ poise.

Then, the upper mold 161 is pressed by driving a pressurizing rod (not shown), and the upper mold 161 and the lower mold 162 are brought close to each other to press the glass preform GP to perform precision press molding. In this step, the obtained glass preform GP is subjected to precision press molding to cause the convex portion GT to disappear, thereby obtaining a precision molding step of the optical element. In this case, the glass preform GP can be accurately aligned in the plan view position (center axis) of the glass preform GP and the molding surface 161a of the upper mold 161 and the molding surface 162a of the lower mold 162 in a high-precision manner. The center of the center is properly suppressed.

The convex portion GT and the concave portion GR formed on the glass preform GP are completely eliminated by precision press molding. In other words, in the manufacturing stage of the glass preform GP, how to form the convex portion GT and the concave portion GR which can be surely eliminated by the precision press molding of the precision press molding die 160 on the glass preform GP is important. of. Here, the convex portion GT and the concave portion GR formed on the glass preform GP are eliminated by the precision press molding, and it is considered that the cross-sectional shape of the convex portion GT and the concave portion GR is wavy (considering the floating stability of the molten glass block YG) Arranging along the concave shape of the molding surface 132 of the lower mold 130, etc., so as to have a cross-sectional shape The shape becomes a shape in which the curvature gradually changes like a wave shape).

First, the present inventors produced the glass preform GP, and performed precision press molding using the obtained glass preform GP, and observed the obtained optical element to confirm the convex portion GT formed on the glass preform GP. And the recess GR has completely disappeared. At this time, the lower mold 130 used for molding the glass preform GP had a gas discharge hole diameter of 50 μm and a gas discharge hole pitch of 200 μm. In the case of using such a lower mold 130, the height from the tip end of the mountain portion of the convex portion GT to the bottom portion of the concave portion GR is 0.50 μm to 0.55 μm (first difference) in the vicinity of the central portion of the molding surface 132. The vicinity of the peripheral portion of the surface 132 is 1.60 μm to 1.70 μm (the second difference). This is a result of measurement of the glass preform GP of the same batch as the glass preform GP used for the precision press molding, and the inventors presume that the difference between the top of the convex portion GT and the bottom of the concave portion GR is specific. The present invention can be established by saying that it is 20 μm or less. Further, the smaller the difference between the top of the convex portion GT and the bottom portion of the concave portion GR, the more easily the convex portion GT and the concave portion GR disappear, and it is preferably 10 μm or less, more preferably 5.0 μm or less, and particularly preferably 2.0 μm or less.

Further, in the above example, the pitch of the top of the convex portion GT formed on the glass preform GP (the pitch of the gas ejection holes of the lower mold 130), the difference between the top of the convex portion GT and the bottom portion of the concave portion GR The ratio (%) of the value is in the range of 0.25% [(0.50 μm / 200 μm) × 100]) ~ 10% [(20 μm / 200 μm) × 100]), and the upper limit is preferably 5.0% [(10 μm / 200 μm) ) × 100]. In addition, the upper limit of the ratio can be set 2.5% [(5.0 μm/200 μm) × 100], 1.0% [(2.0 μm / 200 μm) × 100], 0.85% [(1.70 μm / 200 μm) × 100], 0.80% [(1. 60 μm / 200 μm) × 100], 0.275% [(0.55 μm / 200 μm) × 100]. From this ratio, it is understood that the ratio of the difference between the top of the convex portion GT and the bottom portion of the concave portion GR is small with respect to the pitch of the top portion of the convex portion GT formed on the glass preform GP of the present invention, and the maximum is only 10 %.

Further, the pitch of the gas ejection orifice and the gas ejection hole can be appropriately changed in consideration of the floating stability of the molten glass lump YG.

On the other hand, as in the above-described Patent Document 1, the glass preform produced by the direct compression of the conventional method has a step in which the cross-sectional shape is sharp, and the step is not eliminated by the precision press molding, and the optical is made optical. The optical performance of the component deteriorates.

After the precision press molding is completed, the precision press molding die 160 and the glass preform GP are cooled to a temperature lower than the glass transition point (Tg) of the glass preform GP. Further, after the precision press molding die 160 and the glass preform GP are cooled for a predetermined period of time, the lower die 162 of the precision press molding die 160 is pulled out from the die 163, and the completed optical component is formed from the molding surface 162a of the lower die 162 ( For example, an aspherical lens is taken out. The optical element thus obtained is an optical element having a high eccentricity accuracy after the molding surface 161a of the upper mold 161 and the molding surface 162a of the lower mold 162 are accurately transferred on the surface.

Optical components formed by precision press molding, temporarily The container accommodated in the holder or the like is subjected to core processing as needed. The core processing means that a known method can be employed for the grinding and polishing processing for removing unnecessary portions of the optical element.

In the above embodiment, at the treatment position 2 of the manufacturing apparatus 200 of the rotary transfer type glass preform, the molten glass lump YG is directly supplied from the position directly above the molding surface 132 of the lower mold 130 by the feeder. However, other embodiments can be employed as shown in FIGS. 9 and 10, that is, on the rotary table 170 different from the manufacturing apparatus 200 of the glass preform, the split mold is provided by the transmission arm portion 171 ( Hereinafter, the upper floating tray 172) is temporarily held by the molten glass lump YG, and then poured into the molding die 220 of the manufacturing apparatus 200 of the preform.

Fig. 9 shows another embodiment (the manufacturing apparatus 230 of the glass preform) in which the molten glass lump YG is poured into the molding die 220 through the other rotating table 170. Fig. 10 shows a state in which the molten glass lump YG is supplied to the molding die 220 after the arm portion 171 provided in the other rotating table 170 is opened. The turntable 170 includes a pair of arm portions 171 formed in a flat shape, and a pair of porous upper floating trays 172 provided at the front end portions of the arm portions 171, and is disposed more than the rotary table 210 of the above-described embodiment. Upper (close to the feeder side). The pair of arm portions 171 are openable and closable so as to be separable in the width direction. The pair of arm portions 171 are closed by an arm opening and closing mechanism (not shown) provided in the arm portion 171, and the molten glass block YG is supported in a floating state by the upper floating tray 172 (sending from below the upper floating tray 172) Above the floating gas, the molten glass block YG is supported by the floating glass), and after the arm portion 171 is opened, the upper floating plate 172 is supplied. The molten glass block YG is supported by the floating support. At this time, the molten glass lump YG is poured to a position higher than the above embodiment. Further, the gas flow rate at the time of pouring and at the time of floating was set to be 0.20 L/min which was the same as that of the above embodiment. The rotary table 170 is intermittently rotated clockwise for a predetermined time, and the arm portions 171 are sequentially passed through the positions 1 to 6. First, at the position 1, the arm portion 171 receives the molten glass lump YG (high-position casting) from the feeder by the upper floating tray 172 in a state where the front end portion is closed. Then, the arm portion 171 is moved to the position 2, and the front end portion is opened in the width direction (horizontal direction). At the treatment position 2 of the manufacturing apparatus 230 of the glass preform, the molten glass block YG that is supported by the floating tray 172 is released. The molding surface 132 is supplied to the lower mold 130 (Fig. 10). When the supply of the molten glass lump YG is completed, the arm portion 171 is kept open in the width direction (horizontal direction), or the arm portion 171 is closed after the position 3, and is sequentially transferred to the position 3-6 and returned to the position 1. At this time, the arm portion 171 is cooled by being transferred to the position 3-6, and is returned to the state at the position 1. In this manner, by supplying the molten glass lump YG to the glass preform molding die 100 through the rotary table 170, the temperature and shape of the molten glass YG can be made uniform, and a high-quality glass preform GP can be produced.

In the example described in the above embodiment, the lower mold 130 has concentric shapes along the concave surface shape of the molding surface 132 of the lower mold 130, and a plurality of (many) gas ejection holes penetrating the vertical direction thereof are regularly formed ( The fine gas ejection hole and the plurality of holes 133, but the diameter and pitch of the gas ejection hole 133 can be set to a desired size in accordance with the specific gravity of the glass material, the shape, size, and molding accuracy of the glass preform to be obtained.

In the above embodiment, at the time of press molding of the glass preform GP, the large-diameter cylindrical portion 151 of the lower mold 150 is located on the outer circumference of the molding surface 114 of the upper mold 110 and the molding surface 132 of the lower mold 130. Therefore, the outer peripheral surface of the glass preform GP abuts against the large-diameter cylindrical portion 151 of the lower mold dies 150, the outer diameter of the glass preform GP is restricted, the tolerance is reduced, and the thickness deviation of the glass preform GP is also Zoom out. When the glass preform GP thus formed is formed by precision press molding, even if a molding die having a side abutting method (a molding die provided with a die) is used, the glass preform GP cannot be placed. Problems in the molding die. Further, since the glass preform GP has high molding precision, a high-precision optical element can be formed.

On the other hand, the lower mold can have the same function as the mold, or the side free mode in which the mold is omitted. In the case where the side surface is not limited, since the outer diameter of the glass preform GP is not limited, the dimensional deviation (distribution) of the outer diameter and the thickness becomes larger than the side contact type. However, even if it is a molding die in which the side surface is not limited (a molding die in which a die is not provided), since the tilting correction mechanism is provided in the molding apparatus, although the outer diameter dimensional accuracy of the glass preform GP is inferior to that of the side surface contact mode, Appropriate treatment such as coring processing can also be used equivalently to the side contact method.

In the example shown in the above embodiment, the molding surface 114 of the upper mold 110 is brought into contact with the molten glass lump YG in a state where the floating gas is ejected, and then the supply of the gas is stopped before reaching the approaching position, but the invention is not limited thereto. The point is that it will indeed disappear through precision press molding. The convex portion GT and the concave portion GR are formed in the glass preform GP, for example, the supply of gas is stopped before the molding surface 114 of the upper mold 110 comes into contact with the molten glass block YG, and then it is brought to the approaching position. In this case, the molding surface 114 of the upper mold 110 may be brought into contact with the molten glass lump YG before the gas is completely stopped, and when the molding surface 132 of the lower mold 130 comes into contact with the molten glass lump YG, press molding is performed in a state where residual pressure exists. In addition, press molding can be carried out without residual pressure.

Further, the supply of the gas is stopped, and the molten glass YG may be brought into contact with the molding surface 132 of the lower mold 130 before the molding surface 114 of the upper mold 110 is in contact with the molten glass YG, in which case it remains in the glass after press molding. The present invention can be applied to the fact that the wrinkles of the preform GP are within a range which can be eliminated in the case of precision press molding. Preferably, the molten glass lump YG is brought into contact with the molding surface 114 of the upper mold 110 and the molding surface 132 of the lower mold 130 at the same time.

In the example shown in the above embodiment, the molding surface 114 of the upper mold 110 is formed into a convex shape, and the molding surface 132 of the lower mold 130 is formed into a concave shape. However, the shape is not limited thereto, and the shape of the molding surface can be appropriately changed. . For example, the molding surface 114 of the upper mold 110 can be formed into a concave shape or a planar shape, and the molding surface 132 of the lower mold 130 can be formed into a convex shape or a planar shape.

Further, in the example shown in the above embodiment, the radius of curvature R1 of the surface on the upper side of the glass preform GP is larger than the radius of curvature R2 of the surface on the lower side of the glass preform GP, but is not limited thereto, and glass preforming is not limited thereto. The shape of the body GP can also be formed so that the upper side of the glass preform GP The radius of curvature R1 of the face is smaller than the radius of curvature R2 of the face on the lower side of the glass preform GP. In addition, the surface on the upper side of the glass preform GP is a concave surface, and the surface on the lower side of the glass preform GP is a convex surface. However, the surface of the upper surface of the glass preform GP is not limited thereto, and the unevenness of the upper and lower surfaces may be reversed. Or the surface above the glass preform GP can be convex or concave.

The present invention can produce various optical components such as lenses, cymbals, and the like. The lens that can be made includes, for example, a concave lens, a convex lens, a lenticular lens, a biconcave lens, a plano-convex lens, a plano-concave lens, and the like. In the lens produced, the first surface and the second surface may be a spherical surface, an aspheric surface, or a combination thereof.

The surface of the optical element can be coated, chamfered, or coring processed by an antireflection film or the like as needed. Further, in order to improve the elongation of the glass material during press molding and to prevent fusion of the glass material and the molding die, a film such as a carbon film can be formed on the molding surface of the molding die. As the film formation method, a known method can be employed, and for example, sputtering, chemical vapor deposition (CVD), or the like can be employed.

The present invention is applicable to: when the molten glass lump is subjected to press molding, the molten glass block YG is brought into contact at the molding surface 132 of the lower mold 130, and the molding surface 132 of the lower mold 130 can be sucked away by heat from the molten glass lump. The surface shape applied thereon is transferred to the molten glass lump YG, and a range of desired shape accuracy can be obtained.

Finally, the embodiments of the present invention are summarized using drawings and the like.

Manufacturer of glass preform of embodiment of the present invention The method, as shown in Figures 1 to 7, uses opposing molding surfaces (114, 132) and is capable of approaching and separating the upper mold (110) and the lower mold (130), at least in the lower mold (130). The molding surface (132) is formed with a plurality of gas ejection holes (133), and includes the step of molding the lower mold (130) in a state where gas is ejected from the gas ejection holes (133) of the lower mold (130). a step of supplying a molten glass lump (YG) on the surface (132), supporting the molten glass lump (YG) on the molding surface (132) of the lower mold (130), and supporting the molten glass lump (YG) Next, the step of bringing the upper mold (110) and the lower mold (130) close; before the forming surface (114) of the upper mold (110) and the molding surface (132) of the lower mold (130) reach the approaching position, the pair is stopped. The gas ejection hole (133) supplies a gas; in the state where the supply of the gas to the gas ejection hole (133) is stopped, the upper mold (110) and the lower mold (130) are further brought closer to each other to make the molten glass block (YG) and the lower portion a step of contacting the molding surface (132) of the mold (130); and at least in the approaching position, to allow a portion of the molten glass block (YG) to enter in the gas ejection hole (133) of the lower mold (130) The step of press molding.

Further, as shown in Fig. 4, the press forming step is carried out in a state in which the supply of gas to the gas discharge hole (133) is stopped, and the gas residual pressure is present in a state where the residual gas pressure is present.

Further, as shown in Fig. 4, the press forming step is carried out in a state where the discharge of the gas from the gas discharge hole (133) is completely stopped.

Further, the glass preform of the embodiment of the present invention, As shown in FIGS. 5 to 7 , the glass preform (GP) produced by the method for producing a glass preform of the present embodiment is formed in a glass preform (GP) and ejected with a gas. The shape of the hole (133) corresponds to the convex portion.

Further, as shown in Fig. 6, it is preferable that a concave portion formed by a curved surface is formed between adjacent convex portions of the glass preform.

Further, in the method of manufacturing an optical element according to the embodiment of the present invention, as shown in FIGS. 1 to 8, the opposing molding surfaces (114, 132) are used and the upper molds (110) are accessible and separated from each other. The lower mold (130) forms a plurality of gas ejection holes (133) at least on the molding surface (132) of the lower mold (130), and includes the steps of: ejecting gas from the gas ejection holes (133) of the lower mold (130). The molten glass block (YG) is supplied to the molding surface (132) of the lower mold (130), and the molten glass block (YG) is floated and supported on the molding surface (132) of the lower mold (130). a step of bringing the upper mold (110) and the lower mold (130) close together in a state where the molten glass lump (YG) is floated; molding of the molding surface (114) and the lower mold (130) of the upper mold (110) Before the surface (132) reaches the approaching position, the gas supply to the gas ejection hole (133) is stopped; and when the gas supply to the gas ejection hole (133) is stopped, the upper mold (110) and the lower mold (130) are further brought closer. a step of contacting the molten glass block (YG) with the molding surface (132) of the lower mold (130); at least in the approaching position, allowing melting in the gas ejection hole (133) of the lower mold (130) A portion of the extent of glass blocks (YG) into the press molding is performed to obtain a lower mold (130) side of the molding surface (132) is formed with a surface a step of forming a glass preform (GP) corresponding to the shape of the gas ejection hole (133); and subjecting the obtained glass preform (GP) to precision press molding to obtain an optical after the disappearance of the convex portion The finishing step of the component.

Further, as shown in Fig. 4, the press forming step is carried out by reacting the residual pressure of the gas in a state where the gas residual pressure exists in the gas supply hole (133) after the gas supply is stopped.

Further, as shown in Fig. 4, the press forming step is preferably carried out in a state where the gas ejection from the gas ejection hole (133) is completely stopped.

Further, an optical element according to an embodiment of the present invention is manufactured by a method of manufacturing an optical element according to an embodiment of the present invention.

As shown in FIGS. 1 to 7 , the method for producing a glass preform according to the embodiment of the present invention uses an upper mold (110) having opposing molding surfaces (114, 132) and being close to and separated from each other and The lower mold (130) is formed with a plurality of gas ejection holes (133) at least on the molding surface (132) of the lower mold (130), and the molten glass block (YG) is subjected to press molding to obtain a glass preform, and the glass preform is formed. The manufacturing method of the body includes supplying a molten glass lump (YG) to the molding surface (132) of the lower mold (130) in a state where gas is ejected from the gas ejection hole (133) of the lower mold (130), and the lower mold ( 130) a step of supporting the molten glass lump (YG) on the molding surface (132); and supplying the molten glass lump (YG) to the molding surface (132) of the lower mold (130), stopping the gas ejection a step of supplying gas to the hole (133); and, stopping the spraying of the gas In a state where the outlet hole (133) supplies a gas, the upper mold (110) and the lower mold (130) are brought close to each other, and the molten glass block (YG) is brought into contact with the molding surface (132) of the lower mold (130).

Further preferably, the step of stopping the supply of the gas is performed before the molding surface (114) of the upper mold (110) and the molding surface (132) of the lower mold (130) reach the approaching position.

Further preferably, the press forming step is performed at an approaching position.

Moreover, the glass preform of the embodiment of the present invention is a glass preform (GP) manufactured by the method for producing a glass preform of the present embodiment as shown in FIGS. 5 to 7 . The glass preform (GP) has a convex portion (GT) and a concave portion (GR), and the convex portion (GT) and the concave portion (GR) are formed such that the difference from the top of the convex portion (GT) to the bottom portion of the concave portion (GR) Below 20μm.

Further, as shown in Fig. 6, the convex portion (GT) and the concave portion (GR) are preferably formed so as to be at the top of the convex portion (GT) formed at the central portion of the glass preform (GP). The first difference of the portion is larger at the second difference from the top to the bottom (GR) of the convex portion (GT) formed at the peripheral portion of the glass preform.

Further, in the glass preform of the embodiment of the present invention, the difference between the top of the convex portion (GT) and the bottom portion of the concave portion (GR) with respect to the pitch of the top portion of the convex portion (GT) formed at the glass preform GP The ratio (%) of the values may be in the range of 0.25% [(0.50 μm / 200 μm) × 100] ~ 10% [(20 μm / 200 μm) × 100]. In addition, the upper limit of the ratio It can be set to 5.0% [(10 μm / 200 μm) × 100].

Further, the upper limit of the ratio may be set to 2.5% [(5.0 μm/200 μm) × 100], 1.0% [(2.0 μm / 200 μm) × 100], 0.85% [(1.70 μm / 200 μm) × 100], 0.80% [(1.60 μm/200 μm) × 100], 0.275% [(0.55 μm / 200 μm) × 100].

The embodiments disclosed above are merely illustrative and not intended to limit the invention. The scope of the present invention is defined by the scope of the claims and the scope of the claims and the scope of the claims.

110‧‧‧上模

111‧‧‧Great Path Department

113‧‧‧Little Trails Department

114‧‧‧ molding surface

121‧‧‧ Large diameter tubular

130‧‧‧下模

132‧‧‧ molding surface

133‧‧‧ gas ejection holes (fine gas ejection holes, most holes)

YG‧‧‧ molten glass block (softened glass block)

GP‧‧‧glass preforms

GT‧‧‧ convex

GR‧‧‧ recess

Claims (14)

A method for producing a glass preform, wherein a plurality of gas ejection holes are formed on at least a molding surface of the lower mold by using a molding surface having a facing surface and capable of approaching and separating the upper mold and the lower mold, and having the following steps a step of supplying a molten glass lump to the molding surface of the lower mold in a state where the gas is ejected from the gas ejection hole of the lower mold, and supporting the molten glass block on the molding surface of the lower mold; a step of bringing the upper mold and the lower mold into close contact with the molten glass lump; and stopping the supply of gas to the gas ejection hole before the molding surface of the upper mold and the molding surface of the lower mold reach the approaching position And stopping the supply of the gas to the gas ejection hole, further bringing the upper mold and the lower mold into proximity, and contacting the molten glass block with the molding surface of the lower mold; and at least at the approaching position, in the foregoing The step of press molding the inside of the gas ejection hole of the lower mold to allow a part of the molten glass block to enter. The method for producing a glass preform according to the first aspect of the invention, wherein the press molding step is to prevent the gas residue from being present in a state in which the gas residual pressure is present after the gas supply to the gas discharge hole is stopped. Pressed and implemented. Manufacture of a glass preform as described in claim 1 In the method, the press forming step is carried out in a state in which the discharge of the gas from the gas ejection hole is completely stopped. A glass preform produced by the method for producing a glass preform according to any one of claims 1 to 3, wherein the glass preform is formed with the gas ejection hole The convex part corresponding to the shape. The glass preform according to claim 4, wherein a concave portion formed by a curved surface is formed between the adjacent convex portions. An optical element manufacturing method is characterized in that a plurality of gas ejection holes are formed on at least a molding surface of the lower mold by using opposing molding surfaces and capable of approaching and separating the upper mold and the lower mold, and having the following steps: a step of supplying a molten glass lump to the molding surface of the lower mold in a state where the gas is ejected from the gas ejection hole of the lower mold, and supporting the molten glass block on the molding surface of the lower mold; a step of bringing the upper mold and the lower mold into close contact with the molten glass block; and stopping the supply of gas to the gas ejection hole before the molding surface of the upper mold and the molding surface of the lower mold reach the approaching position; a step of stopping the supply of the gas to the gas ejection hole, further bringing the upper mold and the lower mold into proximity, and contacting the molten glass block with the molding surface of the lower mold; At least in the approaching position, press forming is performed to the extent that a part of the molten glass lump is allowed to enter in the gas ejection hole of the lower mold to obtain a surface on the molding surface side of the lower mold and the gas ejection hole is formed. a step of forming a glass preform of the convex portion corresponding to the shape; and subjecting the obtained glass preform to precision press molding to obtain a finishing step of the optical element after the disappearance of the convex portion. The method for producing an optical element according to the sixth aspect of the invention, wherein the press forming step is performed to prevent the gas residual pressure in a state where the gas residual pressure is present after stopping supply of the gas to the gas discharge hole. Implemented. The method of producing an optical element according to the sixth aspect of the invention, wherein the press forming step is performed in a state in which the discharge of the gas from the gas ejection hole is completely stopped. An optical element manufactured by the method for producing an optical element according to any one of claims 6 to 8. A glass preform is produced by using a relatively opposite molding surface and capable of approaching and separating the upper mold and the lower mold from each other, and at least forming a plurality of gas ejection holes on the molding surface of the lower mold to melt the glass block The glass preform is obtained by press molding, and the glass preform is produced by supplying a molten glass lump to the molding surface of the lower mold in a state where the gas is ejected from the gas ejection hole of the lower mold. The formation of the aforementioned lower mold a step of supporting the molten glass block on the molding surface and supporting the molten glass block on the molding surface of the lower mold, stopping the supply of the gas to the gas ejection hole; and stopping the gas ejection hole In the state in which the gas is supplied, the upper mold and the lower mold are brought close to each other, and the molten glass lump is brought into contact with the molding surface of the lower mold to perform press molding. The method for producing a glass preform according to claim 10, wherein the step of stopping the supply of the gas is performed before the molding surface of the upper mold and the molding surface of the lower mold reach an approaching position. The method for producing a glass preform according to claim 10, wherein the press forming step is performed at an approaching position. A glass preform produced by the method for producing a glass preform according to any one of claims 10 to 12, wherein the glass preform has a convex portion and a concave portion, and the convex portion and the convex portion The concave portion is formed such that the difference from the top of the convex portion to the bottom portion of the concave portion is 20 μm or less. The glass preform according to claim 13, wherein the convex portion and the concave portion are formed to be a first difference from a top portion to a bottom portion of the convex portion formed at a central portion of the glass preform. a top to bottom portion of the convex portion formed by a peripheral portion of the glass preform 2 the difference is larger.