JP2004196636A - Molding device for press molding and method for producing molding using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for production capable of surely and stably demolding an optical element requiring a very high molding precision, after molding, by keeping the precision. <P>SOLUTION: A device for press molding is provided with upper and lower molds having molding faces facing each other and capable of moving away from and getting closer to each other, and with a sleeve to control the upper and lower molds so as to make the axis of the upper mold collinear with that of the lower mold while it encloses the periphery of the molding faces of the upper and lower molds, when they get closer to each other. The upper or lower mold is provided on the periphery of the molding face with a guide part controlled by coming into contact with the sleeve when the upper and lower molds get closer and a non-guide part not coming into contact with the sleeve. Thereby, the device is equipped with a forced demolding means coming close to the molding face by coming near to the non-guide part when the upper and lower molds move away from each other after the press molding and demolding a press molding by coming into contact with at least a part of the periphery of the molding protruding from the non-guide part. The method for producing the press molding comprises steps of feeding a molding raw material to the press molding device, and press-molding the heated and softened molding raw material. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for press-forming an optical element with high precision, which do not require processing such as grinding and polishing after press-forming. In particular, the present invention relates to a molding apparatus and method suitable for molding a lens used in a laser optical system or the like, which has a narrow tolerance of eccentricity (tilt, decenter) related to the coincidence of the upper and lower mold optical axes.
[0002]
[Prior art]
By precision molding, an optical material such as glass or plastic is press-formed using a molding die having a highly mirror-finished molding surface to produce a press-formed body, for example, an optical element.
[0003]
For example, in a case where an optical element is manufactured by pressing and molding with an upper and lower mold while heating and softening a glass material, it is important to stably and surely release the optical element cooled to a predetermined temperature. In addition, in order to maintain high production efficiency, it is effective to release the mold as soon as possible when the temperature reaches a predetermined temperature (for example, when the temperature is lowered to Tg or less) in the cooling step after molding, and to take out the optical element. .
[0004]
However, depending on the material and shape of the molding surfaces of the upper and lower dies, the composition of the molding material, and the mold release temperature, the molded optical element (for example, a lens) sticks to the molding surface, making it impossible to automatically remove the optical element. In particular, when the mold has a convex shape, sticking is likely to occur due to the difference in the coefficient of thermal expansion between the glass and the mold. And, the convex mold is often used for the upper mold of the upper and lower molds, but the optical element stuck to the upper mold molding surface may fall out of a predetermined time or place, and as a result, The problem is large, such as when production stops.
[0005]
Patent Document 1 discloses that the glass material is pressurized so that the radius of the horizontal cross section of the glass molded body is larger than the radius of the outer periphery of the upper mold, and the upper mold is thermally shrunk in the cooling step after the pressurization. In the mold release step, it is arranged on the outer periphery of the upper mold, is in a non-contact state with the glass molded body at the time of pressurization, and moves relative to the upper mold to form an outer periphery of the upper mold forming surface. It describes a method of releasing a glass molded body in close contact with a molding surface by using a forced releasing means having a passing part.
[0006]
Further, in Patent Document 2, a barrel mold capable of regulating the movement axes of an upper mold and a lower mold to be on the same line, a glass molded body in close contact with a molding surface, by contacting a peripheral portion of the glass molded body. Forced release means to be released, and the forced release means is in contact with the peripheral edge of the glass molded body, so as to peel off the glass molded body from the molding surface, the forced release means with respect to the upper mold or lower mold A forming apparatus having moving means for relatively moving is disclosed.
[0007]
[Patent Document 1] JP-A-11-49523
[Patent Document 2] Japanese Patent Application Laid-Open No. 2001-192215
[0008]
[Problems to be solved by the invention]
In the method described in Patent Document 1, a sleeve (forcible release means) regulates the relative position of the upper die and the lower die, thereby preventing the vertical die from shifting. However, since the sleeve also has a function of dropping the glass molded body by a relative movement with respect to the upper mold (forced release), the sleeve is supported via a clearance slidable with the upper mold. Also, there is a slidable clearance between the lower die and the sleeve, and this sliding allows the lower die to approach the upper die. This double slidable clearance reduces the coaxiality of the upper and lower dies, and as a result, the optical axis shift (tilt, decenter) tends to occur in the molded lens. Since the sliding clearance is widened by repeating the molding, the optical axis shift is further deteriorated.
[0009]
In Patent Document 2, the above-mentioned problem is solved by providing a forced releasing means separately from a sleeve for guiding the upper and lower molds and separating functions. That is, as shown in FIG. 5 (corresponding to FIG. 8 of Patent Document 2), the relative position of the upper and lower molds is regulated by the sleeve 32, and only the lower mold slides on the sleeve. Therefore, the shaft displacement of the upper and lower molds is suppressed as compared with the case of Patent Document 1 in which both the upper and lower molds slide with respect to the sleeve. However, since the forcible mold release means is arranged around the upper mold forming surface, the contact surface where the sleeve regulates the upper mold is located very far from the molding surface, and even if the sleeve is slightly inclined, the upper and lower molds may be used. , That is, the decenter of the lens becomes large. When such an optical element is used for a lens for a laser optical system, for example, coma aberration is poor.
[0010]
The present invention provides a manufacturing apparatus and a method capable of reliably and stably performing mold release after molding, while maintaining the precision even for an optical element that requires extremely high molding precision. The purpose is to do. In particular, it is an object of the present invention to provide a molding apparatus and method excellent in the effect of improving the eccentricity accuracy (suppressing decenter and tilt). Another object of the present invention is to provide a manufacturing apparatus and method capable of shortening the molding cycle time and improving productivity.
[0011]
[Means for Solving the Problems]
The present invention for solving the above problems is as follows.
(1) In a press molding apparatus having upper and lower dies having opposite molding surfaces and capable of being separated and approached to each other,
When the upper mold and the lower mold approach each other, surround the outer periphery of the molding surface of the upper mold and the molding surface of the lower mold, and move the upper mold and the lower mold so that the axes of the upper mold and the lower mold are on the same line. With a regulating sleeve,
The upper mold or the lower mold has, on the outer periphery of the molding surface, a guide portion which is regulated by contacting the sleeve when the upper mold and the lower mold approach each other, and a non-guide portion which does not contact the sleeve,
After press molding, when the upper mold and the lower mold are separated, by approaching the non-guide portion, it is in close contact with the molding surface, and at least a part of the peripheral portion of the press molded body protruding from the non-guide portion. The apparatus according to claim 1, further comprising forcible release means for releasing the press-formed body by contact.
(2) The upper mold has the guide portion and the non-guide portion on the outer periphery of a molding surface, and the forcible mold release means is for releasing the press molded body in close contact with the upper mold molding surface. The apparatus according to (1), wherein:
(3) The method according to (2), further including a moving unit configured to move the forcible mold releasing unit relatively to the upper mold in conjunction with a movement of the upper mold and the lower mold separated after press molding. apparatus.
(4) The guide part of the upper mold forms an arc, and the inner periphery of the sleeve has a cylindrical shape. When the upper mold and the lower mold approach, the guide part comes into contact with the sleeve. The device according to (2) or (3), wherein the guide is regulated so that the axes of the upper mold and the lower mold are on the same line.
(5) an upper mold and a lower mold having opposite molding surfaces and capable of being separated and approached from each other;
A sleeve that surrounds the outer periphery of the molding surface of the upper mold and the lower mold to regulate the position of the upper and lower molds,
After press molding, if there is a press molded body in close contact with any of the molding surface, by contacting at least a part of the outer edge portion thereof, to a press molding device having forced release means for releasing the press molded body ,
In a method of manufacturing a press-formed body including supplying a forming material and performing press forming in a state where the forming material has been softened by heating,
The press molding apparatus has an upper die or a lower die on the outer periphery of a molding surface, a guide portion that contacts the sleeve when the upper die and the lower die approach each other, and a non-guide portion that does not contact the sleeve, The sleeve regulates the upper and lower dies so that the axes of the upper and lower dies are on the same line when approaching the upper and lower dies for press molding,
The press molding is performed so that at least a part of the formed press molded body peripheral portion protrudes from the non-guide portion of the molding surface, and
When the upper mold and the lower mold are separated from each other after press molding, the forced mold release means approaches the non-guide portion and, when there is a press molded body in close contact with a molding surface, the non-guide portion of the press molded body. The method according to any one of claims 1 to 3, wherein the press-formed body is released from the mold by contacting a portion of the press-formed body.
(6) The press-formed body includes a free surface in which a portion protruding from a non-guide portion is formed by press-forming, and the forcible mold release means releases the press-formed body by coming into contact with the free surface. The method according to (5), wherein
(7) the upper mold has a guide portion and a non-guide portion on the outer periphery of the molding surface,
The forcible mold release means, when there is a press molded body in close contact with the upper mold forming surface, releases the press molded body by contacting a portion of the press molded body that protrudes from the non-guide portion. The method according to claim 5, wherein
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the press forming apparatus of the present invention will be described.
The apparatus of the present invention has an upper mold and a lower mold that can be separated from and approached to each other, and the upper mold and the lower mold face each other, and a surface for molding a press-formed material (this is referred to as a molding surface). Have. The molding surface has a predetermined shape and surface accuracy, and may include a transfer surface that transfers the surface to the surface of the press-formed body, and a non-transfer surface around the transfer surface. The molding material is glass, plastic, or the like. The shaped body can be an optical element, for example a lens.
[0013]
Further, the apparatus of the present invention is provided with a forced release means for releasing the press-formed body when the press-formed material comes into close contact with one of the forming surfaces of the upper and lower dies after press-forming the press-formed material. Forcible mold release means, for example, in order to release the press molded body in close contact with the molding surface of the upper mold, provided around the upper mold, to release the press molded body in close contact with the molding surface of the lower mold Is provided around the lower mold. In the present invention, even if the press-formed body is in close contact with any of the molding surfaces of the upper mold and the lower mold, the upper mold and the lower mold are provided with forced release means so that the press-molded body can be released. You can also.
[0014]
Hereinafter, in the embodiment, in order to release the press molded body in close contact with the molding surface of the upper mold, for a device provided with a forced mold release means around the upper mold molding surface, using glass as a molding material, A description will be given of molding of a glass lens as an example.
[0015]
FIG. 1 is a schematic cross-sectional view of a side surface of a molding die, showing a configuration of an embodiment of a molding device of the present invention. FIG. 1 is a horizontal sectional view of a portion including an upper die and a release ring (forced release means), as viewed from the Y direction in FIG.
The molding apparatus includes a mold 10 shown in FIG. 1 and a transport mechanism including a cylinder or a servomotor for moving the lower portion 14 of the mold vertically, as will be described later, although not shown, and a mold. A heater (for example, a high-frequency coil) for directly or indirectly heating a predetermined member in 10 is provided. The molding die 10 is mounted in such a molding device.
[0016]
Each component member of the molding die 10 is substantially cylindrical, except in the case where details differ, and the lower plate 61 is formed by a molding die upper portion 12 fixed together with the upper plate 60 at a predetermined position and a cylinder (not shown). And a lower mold part 14 movable in the vertical direction.
In FIG. 1, the upper mold portion 12 and the lower mold portion 14 are in contact with each other, but are separated when supplying a glass material and taking out a glass lens, as described later.
The upper mold part 12 is mainly located concentrically with the hollow cylindrical upper mother mold 18, the upper mother mold 18, and presses the glass material at its lower end surface to form the upper mold 20, and concentric with the above members. And an upper sleeve 24 located at Further, a release ring 25 which is concentric with the upper die and the upper sleeve and which corresponds to a forced release means surrounding the outer periphery of the upper die is provided.
[0017]
The lower mold part 14 is located on a lower plate 61 fixed to a cylinder (not shown) at the lower surface thereof, and is formed concentrically with the lower mother mold 28 having a hollow cylindrical shape. A lower mold 30 adapted to receive a glass material at a molding surface which is an upper end surface, and a lower sleeve 34 which is concentric with the lower mold and the lower mold and surrounds the lower mold molding surface.
[0018]
The upper mold 20 and the lower mold 30 correspond to “an upper mold and a lower mold having opposing molding surfaces and capable of being separated from and approached to each other”.
Further, the lower sleeve 34 corresponds to “a sleeve that surrounds the outer periphery of the molding surface of the upper die and the molding surface of the lower die and regulates the axes of the upper die and the lower die so that they are on the same line”.
[0019]
The hollow cylindrical upper mother die 18 accommodates the upper die 20 and the upper sleeve 24 inside thereof, and has an inner peripheral surface in contact with the outer peripheral surface of the upper sleeve 24. . Further, the lower surface of the upper mother die 18 comes into contact with the upper surface of the lower mother die 28 when the glass material is pressed (at the time of molding) (FIG. 1 shows a state in which the upper mother die 18 is in contact with the upper surface). The lower end surface of the upper mold 20 is a molding surface, and the shape is processed based on one surface shape of a desired glass molded body.
[0020]
The upper sleeve 24 is provided with a protruding portion 44 protruding radially outward, and the spring 2 is disposed between the lower surface of the protruding portion and the protruding portion 19 protruding radially inward of the upper matrix 18. . As a result, the upper sleeve 24 is urged upward and abuts on the lower surface of the upper plate 60 to maintain the verticality. Further, when the upper mold and the lower mold that have been separated approach each other, the upper sleeve 24 fits into a donut-shaped hole formed by the lower sleeve 34 and the lower mother mold 28, which will be described later. Then, its inner peripheral surface comes into contact with the outer peripheral surface of the lower sleeve. (Note that, as described later, when press molding is performed with the upper and lower dies closer to each other, the upper die 20 is guided with higher accuracy by the lower sleeve 34 near the molding surface.)
[0021]
The lower mold 30 is positioned by the inner peripheral surface of the lower mold 28. The upper end surface of the lower die 30 is a molding surface, and the shape is processed based on the other surface shape of the desired glass molded body.
[0022]
The upper mold 20, the lower mold 30, the upper sleeve 24, and the lower sleeve 34 of the molding die 10 are made of, for example, metals such as Mo and W, WC (hard metal), silicon carbide, silicon, silicon nitride, and aluminum oxide. Or a cermet of titanium carbide, and it is preferable that a protective film is formed on the surface thereof for the purpose of improving oxidation resistance, durability, and fusion resistance. As the protective film, a thin film made of a noble metal material containing Pt, Rh, Au, Re, Os, Ir, etc., a hard carbon film, a carbon-based thin film such as diamond-like carbon, SiC, Si _Three N _Four And a thin film made of a ceramic material such as titanium carbide, titanium nitride, and alumina, and a composite material thereof. The protective film can be formed by, for example, a sputtering method, an ion plating method, a CVD method, or the like, and may be a single-layer film or a multilayer film made of different materials. In particular, the molding surfaces of the upper mold and the lower mold are formed by processing silicon carbide by a CVD method, and then forming an amorphous and / or crystalline graphite such as an i-carbon film by an ion plating method and / or diamond. It is preferable to form a carbon film composed of a single component layer or a mixed layer. The reason is that even if the molding is performed at a relatively high mold temperature, fusion does not occur, and the mold can be easily released at a relatively high temperature because of good releasability. The upper matrix 18 and the lower matrix 28 can be made of, for example, metal. Preferably, the upper matrix 18 and the lower matrix 28 are made of a material such as a tungsten alloy, and those that generate heat by induction of a high-frequency coil are used.
[0023]
The glass molded article manufacturing apparatus of the present invention has "forced mold release means for releasing the press molded article by contacting at least a part of the periphery of the press molded article" which is in close contact with the molding surface after press molding. However, in the apparatus shown in FIG. 1, the release ring 25 corresponds to a forced release means.
[0024]
In the apparatus for manufacturing a glass molded body of the present invention, in conjunction with the movement of the upper mold and the lower mold being separated, the forced mold releasing means is further moved relative to the upper mold or the lower mold (the upper mold in the embodiment shown in FIG. 1). In the device shown in FIG. 1, the spring 1 corresponds to the moving means.
[0025]
The forcible mold release means releases the glass molded body in close contact with the molding surface by coming into contact with at least a part of the periphery of the glass molded body. As will be described later, this contact is performed by moving the forcible release means relative to the upper mold by the action of the moving means so that the glass molded body in contact with the forcible release means is separated from the molding surface. Can be. That is, the forcible mold release means moves relative to the upper mold a distance such that the glass molded body is separated from the molding surface after press molding. Further, when the upper mold and the lower mold approach each other to press the glass material, the forcible mold release means is directly or indirectly pushed up by the lower mold and retracts, and the glass molding formed by pressurization. It can be in a state of non-contact with the body. This does not hinder the forming of the glass molded body. Then, only when the upper mold and the lower mold are separated from each other in order to release the glass molded body, the glass molded body comes into contact with the forced release means and is peeled off from the molding surface.
[0026]
The forcible mold release means described in this aspect is for releasing the glass molded body in close contact with the upper mold molding surface by contacting at least a part of the periphery of the glass molded body. The forcible mold release means may be, for example, a ring-shaped one that is externally fitted to the upper mold so as to be able to come into contact with at least a part of the peripheral edge of the glass molded body in close contact with the upper mold molding surface. it can.
[0027]
The moving means is forcibly released so that when the upper mold and the lower mold are separated from each other, the forced mold releasing means comes into contact with at least a part of the peripheral edge of the glass molded body and peels the glass molded body from the molding surface. This is for moving the mold means relatively to the upper mold. When the forcible release means is for releasing the glass molded body in close contact with the upper mold forming surface, the moving means is compressed by the forcible release means being directly or indirectly pushed up by the lower mold. Biasing means for storing the biasing force. Pushing up of the forced release means by the lower mold occurs when the upper mold and the lower mold approach when the glass material is pressed, and the forced mold release means also approaches the lower mold. Depending on the structure (components) of the molding apparatus, the lifting of the forced release means by the lower mold can be performed directly while abutting on the lower mold or indirectly via a lower sleeve or the like. Such an urging means can cause the forced mold releasing means to follow the lower mold when the upper mold and the lower mold are separated from each other. It comes into contact with the molded body and can be separated from the molding surface.
[0028]
The urging means may be an elastic body such as a spring, a bar spring, or a leaf spring. The moving means may be means other than the urging means (for example, a mechanism such as a servomotor for giving a vertical displacement to the releasing means may be provided). There is an advantage that the mounting and the configuration of the device can be simplified. The forced release means can be made of a heat-resistant material, for example, SUS (stainless steel) or a tungsten alloy. Further, the biasing means may be an elastic body made of a heat-resistant material, for example, a ceramic such as zirconia or a metal.
[0029]
As shown in FIG. 1, in this embodiment, the spring 1 is an urging means. The spring 1 is wound between the upper die 20 and the release ring 25, and the upper end thereof is in contact with the lower surface of the flange portion of the upper die 20, and the lower end is in contact with the release ring 25. Therefore, the release ring 25 is urged downward from the upper die.
[0030]
In the apparatus of the present invention shown in FIGS. 1 and 2, the upper mold has at least on the outer periphery of the molding surface a guide portion that is restricted by coming into contact with the sleeve and a non-guide portion that does not come into contact with the sleeve. When the upper and lower dies separate from each other after press molding, the forcible mold release approaches the non-guide portion, and when passing near the peripheral edge of the molding surface, when there is a press molded body that is in close contact with the molding surface, the peripheral portion is This can be released by contact.
[0031]
In the molding die 10 shown in FIG. 1, the release ring 25, which is a forced releasing means, is arranged around the outer periphery of the upper die 20 in order to release the molded body that is in close contact with the molding surface of the upper die 20. The guide portion and the non-guide portion are provided on the outer periphery of the molding surface of the upper mold 20. As shown in FIG. 1, when the upper and lower dies approach, the outer periphery of the molding surface of the upper die 20 is in contact with the inner peripheral surface of the lower sleeve 34. The portion in contact with corresponds to the guide portion of the upper die 20.
[0032]
FIG. 2 is a schematic cross-sectional view of a side surface of a molding die showing a configuration of one embodiment of the present invention similar to FIG. 1, and FIG. 1 is a horizontal cross-sectional view of a portion including an upper die and a release ring. 3 is a view from the Y direction, while FIG. 2 is a view from the X direction. 2A shows the state of the apparatus at the time of press molding, and FIG. 2B shows the state at the time of mold release after pressing.
[0033]
As shown in FIG. 2A, similarly to FIG. 1, when the upper and lower dies are approaching, the inner periphery of the lower sleeve 34 surrounds the outer periphery of the molding surface of the upper dies 20. The outer periphery of the molding surface is not in contact with the inner periphery of the lower sleeve. The portion of the outer periphery of the molding surface of the upper die 20 that is not in contact with the lower sleeve 34 corresponds to the non-guide portion of the upper die 20.
Here, the press-formed body pressed between the upper and lower dies is formed to project radially outward from the non-guide portion of the upper die.
[0034]
R1, r2, d, R and R2 in FIG. 3 mean the following dimensions.
r1: radius of guide
r2: distance from the center of the non-guide part
d: radius of release ring 25, which is a forced release means
R: radius of lens
R2: radius of the optical function surface of the lens
[0035]
More specifically, as shown in FIG. 3, the horizontal section of the guide portion on the outer periphery of the molding surface of the upper mold 20 is, for example, an arc having a radius r1 as shown in FIG. The inner circumference of 34 can also be an arc of radius r1. When the upper and lower dies are separated or approach by the guide portion, the arc portion comes into contact with the sleeve and is guided while sliding, so that the axes of the upper and lower dies are regulated to be the same line. The clearance between the lower sleeve 34 and the upper die guide portion is, for example, 0.5 to 10 μm, so that the vertical movement relative to the sleeve (here, the lower sleeve) can be performed without causing the upper die to tilt or shift its axis. It is preferable because it can be performed.
On the other hand, the lower mold 30 does not move up and down relative to the lower sleeve 34, and can be integrated with both. It should be noted that the molding surface may be formed as a separate body in terms of ease of processing, and in FIGS. 1 and 2, it is formed as a separate body.
[0036]
The non-guide portion has, for example, a portion where the distance from the center of the upper die to the non-guide portion is r2 on the horizontal cross section of the outer periphery of the upper mold forming surface. As shown in FIG. 3A, the distance (r2) from the center of the cross section of the upper die to the non-guide portion of the upper die 20 is slightly smaller than the radius r1 of the guide portion (r2 <r1). The non-guide portion does not contact the inner circumference of the lower sleeve 34 which is substantially equal to r1.
[0037]
As described above, the outer periphery of the molding surface of the upper mold has, in a horizontal cross section, a guide portion whose distance from the center is r1 and a non-guide portion whose distance from the center is smaller than r1. For example, as shown in FIG. 3 (a), the guide portion and the non-guide portion are provided with two guide portions and two non-guide portions at positions facing each other. Can be. The guide portion whose outer periphery has a radius of r1 is drawn in an arc, and as described later, during molding, the guide portion and the inner peripheral surface of the lower sleeve having an inner radius of approximately r1 are accurately (with lateral displacement and inclination). Without contact). On the other hand, the horizontal cross section of the non-guide portion whose distance from the cross section center of the upper die is r2 may be either a straight line or a curve. As shown in FIG. 3 (b), one guide portion and one non-guide portion are provided on the outer periphery of the molding surface of the upper die, or as shown in FIG. 3 (c), three guide portions are provided. And the three non-guide portions may be provided at alternately opposed positions. Further, the horizontal cross section of the upper mold may be a polygon other than the shapes shown in FIGS.
[0038]
In short, at the time of molding, at least a part of the outer periphery of the upper mold is guided by the sleeve, and a guide portion capable of moving up and down relative to the sleeve (here, the lower sleeve) without causing inclination or axial misalignment; The other part of the outer periphery of the mold is retracted from the guide part, so that a part of the peripheral part of the press-formed body that has been pressed can protrude outside the upper molding surface, and It is sufficient that the upper die has a non-guide portion that allows contact of the release ring.
[0039]
However, the cross-sectional shape of the upper mold (shape and arrangement of the guide part and the non-guide part) is such that as much as possible the outer peripheral surface of the upper mold is guided and regulated by the sleeve in order to prevent axial misalignment between the upper and lower dies. It is preferable to set the guide portion to be used.
[0040]
Further, in the device of the present invention, the distance between the forced release means and the non-guide portion on the horizontal cross section is set smaller than the distance between the sleeve and the non-guide portion.
As shown in FIG. 3 (a), the distance (gap) between the release ring and the non-guide portion (d-r2) is the distance (gap) between the lower sleeve and the non-guide portion, that is, the outer edge of the press-formed body. Smaller than the distance (R-r2) between the guide and the non-guide portion. As a result, the release ring comes into contact with the peripheral portion of the press-formed body that protrudes from the non-guide portion, and peels the press-formed body from the forming surface. That is, in the apparatus of the present invention, when the release ring has a portion whose distance from the center is d on a horizontal cross section and presses a press-formed body having an outer radius R, if R> d, The press-formed body can be released from the molding surface. It is preferable that R and r2 satisfy r2 + 1 mm ≧ R ≧ r2 + 0.1 mm from the viewpoint of reliably releasing the mold without making the optically functional surface of the press-formed body unnecessarily small.
[0041]
The clearance between the release ring 25 and the outer periphery of the upper mold needs to be large enough to allow the release ring 25 to pass over the upper mold forming surface in the guide portion. It is appropriate that the mold ring 25 is set so as to be able to come into contact with the vicinity of the peripheral edge of the press-formed body without contacting the upper die forming surface. It is appropriate that the clearance between the guide portion and the release ring is, for example, in the range of 0.05 to 0.5 mm. Further, it is appropriate that the clearance between the non-guide portion and the release ring is, for example, in the range of 0.05 to 0.3 mm. The clearance between the outer peripheral surface of the release ring and the inner peripheral surface of the upper sleeve can be 0.03 to 0.2 mm.
[0042]
Hereinafter, the operation of the molding apparatus configured as described above and the manufacturing method of the present invention will be described.
First, a glass material is supplied onto the molding surface of the lower mold 30 by a jig (not shown) that holds a molding material (for example, a glass material) in a state where the molding die lower portion 14 is lowered. . The glass material may be supplied at room temperature, or may be supplied after being heated to a predetermined temperature in advance. Preferably, a glass material previously heated to a viscosity suitable for a press can be supplied to the mold 10 preheated to a predetermined temperature. Further, the softening of the glass material by heating can be performed while the glass material is levitated by an air current.
[0043]
In a low-viscosity region where the glass material is deformed by its own weight, it is very difficult to prevent the glass from being fused with the jig holding the glass material during heating. On the other hand, a gas layer is formed between the jig surface and the glass material surface by ejecting gas from the inside of the jig, causing the glass material to float by the air current, and as a result, the jig and The glass can be softened by heating without reacting. Furthermore, when the glass material is a preform, it can be softened by heating while maintaining the shape of the preform. In addition, even if the glass material is a glass gob and has an irregular shape with surface defects such as wrinkles, it is possible to adjust the shape and erase the surface defects by floating by airflow while heating and softening. is there.
[0044]
The preheating temperature of the glass material is 10 ⁶ ~Ten ⁹ The temperature of the molding surface of the upper and lower molds is 10 ⁹ ~Ten ¹² Preferably, the temperature is equivalent to poise.
[0045]
In this way, when the glass material is supplied to the lower mold 30 and the upper and lower molds and the glass material are each at a predetermined appropriate temperature, the lower mold part 14 of the mold 10 is driven by a driving means such as a cylinder or a servomotor (see FIG. (Not shown) to engage the upper mold part 12. At this time, first, as the lower part 14 of the molding die rises, the lower side of the upper sleeve 24 is fitted into a donut-shaped hole between the lower sleeve 34 and the lower mother mold 28. That is, the lower sleeve 34 is guided inside the upper sleeve 24 and enters the inside of the upper sleeve 24. Since the upper sleeve 24 is pressed against the upper plate 60 by the spring 2, the inclination of the upper sleeve 24 can be prevented, so that the lower sleeve 34 also enters the inside of the upper sleeve 24 without being inclined.
[0046]
Next, the lower mold portion 14 is further pushed upward, so that the upper mold surface portion fits into the lower sleeve 34. Thereby, both the upper and lower dies are regulated by the lower sleeve 34 (the upper dies are regulated by the lower sleeve 34 by the guide portion). Moreover, the upper and lower dies are regulated by the lower sleeve 34 at a position very close to the molding surface, and the clearance required for sliding is only between the upper dies 20 and the lower sleeve 34 (the sliding portion in FIG. 1). And the lower mold are held with high coaxiality, and tilt (tilt) and optical axis shift (decenter) are suppressed.
[0047]
Thereafter, the molding surface, which is the lower end surface of the upper mold 20, comes into contact with the glass material, and the glass material is pressed. At this time, the lower part 14 of the mold is, for example, about 100 kg / cm by a piston or the like. ^Two The glass material is pressed with a moderate pressure.
[0048]
At the time of the press, the release sleeve 25 is moved upward against the spring 1 by pushing up the lower sleeve 34. Therefore, during the pressing, the release ring 25 is retracted upward, and does not come into contact with the press-formed body. The thickness of the press-formed body (lens) is determined in a state where the lower end surface of the upper mold 18 and the upper end surface of the lower mold 28 are in contact with each other. This is the state shown in FIGS. 1 and 2 (a).
[0049]
In this state, the outer radius R of the press-formed body is larger than r2 and does not exceed r1, as shown in FIG. Therefore, in the non-guide portion (the portion on the outer periphery of the upper molding surface and the distance from the center is r2), the outer edge portion of the press molded body projects slightly outside the molding surface of the upper die. Preferably, the outer peripheral radius of the pressed body is approximately r1.
[0050]
Also preferably, as shown in FIG. 4 (a), a portion of the natural surface formed at the outer edge of the pressed body when pressed by the upper mold forming surface (a portion not in contact with the forming surface of the forming die) or The amount of the glass material and the molding apparatus are adjusted so that only a part thereof projects from the upper mold forming surface. FIGS. 4A and 4B are partial cross-sectional views of the vicinity of a non-guide portion of a molding die including a press molded body.
[0051]
The portion (transfer surface) of the press-formed body pressed by the upper mold forming surface can be larger than the optical function surface of the press-formed body (lens). In other words, a lens having an optical function surface with a radius of r2 or less can be formed. (See Fig. 3 (a))
[0052]
Next, in the state shown in FIG. 1 or FIG. 2 (a), the formed lens is cooled at a predetermined cooling rate until the temperature becomes equal to or lower than the transition point of glass. The cooling rate is preferably 50 ° C./min or more.
[0053]
When the lens is cooled to a predetermined temperature (for example, around Tg), the lower part 14 of the mold 10 is lowered to release the lens.
[0054]
As the lower mold part 14 moves down, the release ring 25 of the upper mold part 12 is moved downward by the urging force of the spring 1. Therefore, when the release ring 25 is lowered, the above-described lens L that has adhered to the upper mold 20 comes into contact with the portion of the peripheral edge of the lens L that protrudes outside the upper mold forming surface non-guide portion. Is pushed downward. FIG. 2B shows a state immediately after the lens L is released from the upper die by the release ring. The movement of the portion within the circle A in FIG. 2B is shown in FIGS. 4A and 4B. FIG. 4A shows a state in which the release ring 25 is lowered and approaches the periphery of the lens L, and the lens L is attached to the upper mold forming surface. FIG. 4B shows a state in which the release ring 25 further descends and comes into contact with the lens L to be released. The release ring 25 is in contact with the free surface portion of the peripheral portion of the lens L to separate the lens L from the upper mold forming surface. Then, although not shown in FIG. 4, the lens L falls on the lower mold 30.
As shown in FIG. 3, since the part whose distance from the center of the release ring is d is slightly smaller than the radius R of the outer periphery of the molded lens, it contacts the outer edge of the lens and depresses the lens to release the mold. .
In this way, the release ring contacts the outer peripheral portion of the optical function surface, which is the peripheral portion of the lens to be molded, and separates the lens from the molding surface. Therefore, the optical function surface of the lens is not damaged.
[0055]
After the lens is released from the mold in this manner, the lower mold part 14 is lowered to a predetermined position, and the lens on the lower mold 30 is taken out using a take-out means such as a suction pad (not shown). The removed lens is annealed as needed.
[0056]
The press-formed body formed by the apparatus of the present invention can be, for example, an optical element, and more specifically, includes a concave lens, a convex lens, an aspheric lens such as a meniscus lens, and various optical elements such as a cylindrical lens. be able to. When the press-formed body obtained by the apparatus and the manufacturing method of the present invention is an optical element, the decenter can be 10 μm or less, preferably 5 μm or less, and the tilt can be 2 ′ (2 minutes) or less. Further, the press-formed body obtained by the apparatus and the manufacturing method of the present invention can be, for example, a disk substrate or the like.
[0057]
In the above description, the lens attached to the upper mold is released by the release ring arranged around the upper mold, but the lens attached to the lower mold side is arranged around the lower mold. It is also possible to release the mold by the same means.
[0058]
【The invention's effect】
In the present invention, since the molded lens is reliably released from the molding surface, that is, sticking to the molding surface is prevented, and an excellent effect of improving productivity is brought about.
In the present invention, a sleeve for accurately positioning the molding surface and a means for forcibly releasing the lens attached to the molding surface (a release ring in the above embodiment) are both disposed near the molding surface. Made it possible to do so. This can be achieved by coexisting a guide portion that is restricted by a sleeve and a non-guide portion that allows the release ring to approach on the outer periphery of the molding surface of the molding die (the upper die in the above embodiment). Was.
[0059]
If only the release ring is arranged in the vicinity of the molding surface as in the prior art, the sleeve for controlling the position of the upper mold cannot be arranged in the vicinity of the molding surface, and the optical axis shift (decenter) increases. On the other hand, if the release ring also serves as a position regulating function, it is necessary to slide both the upper and lower dies, so that the optical axis shift (decenter, tilt) of the upper and lower dies increases.
[0060]
The present invention has solved these problems and achieved stable production of a lens with high eccentricity. Particularly, it is usefully used for an optical disk optical type using laser light, which requires particularly strict coaxiality (eccentricity accuracy).
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a side surface of a mold, showing a configuration of an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a side surface of a molding die showing a configuration of an embodiment of the present invention, including a molded body, showing a state immediately after pressing (a) and a state at the time of releasing (b). is there.
FIG. 3 is a horizontal sectional view of a portion including an upper die and a release ring of a molding die according to an embodiment of the present invention.
FIG. 4 is an enlarged view of a circle of FIG. 2;
FIG. 5 corresponds to FIG. 8 of Patent Document 2.
[Explanation of symbols]
1,2 spring
10 Mold
12 Upper mold
14 Mold lower part
18 Upper mold
20 Upper type
24 Upper sleeve
25 Release ring
28 Lower mold
30 lower mold
34 Lower sleeve
60 Upper plate
61 Lower plate
L lens

Claims (7)

In a press molding apparatus having upper and lower dies having opposing molding surfaces and capable of being separated and approached to each other,
When the upper mold and the lower mold approach each other, surround the outer periphery of the molding surface of the upper mold and the molding surface of the lower mold, and move the upper mold and the lower mold so that the axes of the upper mold and the lower mold are on the same line. With a regulating sleeve,
The upper mold or the lower mold has, on the outer periphery of the molding surface, a guide portion which is regulated by contacting the sleeve when the upper mold and the lower mold approach each other, and a non-guide portion which does not contact the sleeve,
After press molding, when the upper mold and the lower mold are separated, by approaching the non-guide portion, it is in close contact with the molding surface, and at least a part of the peripheral portion of the press molded body protruding from the non-guide portion. The apparatus according to claim 1, further comprising forcible release means for releasing the press-formed body by contact. The upper mold has the guide portion and the non-guide portion on the outer periphery of a molding surface, and the forcible mold release means is for releasing the press molded body in close contact with the upper mold molding surface. The device according to claim 1, characterized in that: The apparatus according to claim 2, further comprising a moving unit configured to move the forced mold releasing unit relatively to the upper mold in association with a movement of the upper mold and the lower mold separated after press molding. The guide part of the upper mold forms an arc, and the inner periphery of the sleeve has a cylindrical shape, and when the upper mold and the lower mold approach, the guide part comes into contact with the sleeve and is guided. The apparatus according to claim 2, wherein the axes of the upper mold and the lower mold are regulated so as to be on the same line. An upper mold and a lower mold having opposing molding surfaces and capable of being separated from and approached to each other;
A sleeve that surrounds the outer periphery of the molding surface of the upper mold and the lower mold to regulate the position of the upper and lower molds,
After press molding, if there is a press molded body in close contact with any of the molding surface, by contacting at least a part of the outer edge portion thereof, to a press molding device having forced release means for releasing the press molded body ,
In a method of manufacturing a press-formed body including supplying a forming material and performing press forming in a state where the forming material has been softened by heating,
The press molding apparatus has an upper die or a lower die on the outer periphery of a molding surface, a guide portion that contacts the sleeve when the upper die and the lower die approach each other, and a non-guide portion that does not contact the sleeve, The sleeve regulates the upper and lower dies so that the axes of the upper and lower dies are on the same line when approaching the upper and lower dies for press molding,
The press molding is performed so that at least a part of the formed press molded body peripheral portion protrudes from the non-guide portion of the molding surface, and the forcible mold releasing means includes an upper die and a lower die after press molding. When separated, when there is a press-formed body approaching the non-guide portion and closely contacting the molding surface, the press-formed body comes into contact with a portion of the press-formed body that protrudes from the non-guide portion, and the press-formed body is released. The above-mentioned manufacturing method, characterized in that: The press-molded body includes a free surface in which a portion protruding from a non-guide portion is formed by press-molding, and the forcible mold release means releases the press-molded body by contacting the free surface. The method according to claim 5, wherein The upper mold has a guide portion and a non-guide portion on the outer periphery of the molding surface thereof, and the forcible mold release means includes, when there is a press molded body in close contact with the upper molding surface, the non-molded portion of the press molded body. The manufacturing method according to claim 5 or 6, wherein the press-formed body is released by contacting a portion protruding from the guide portion.

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