JP5704172B2 - Molding equipment - Google Patents

Description

The present invention relates to a preferred molding equipment for molding a lens with high accuracy.

  In recent years, a light capable of recording and / or reproducing information (hereinafter referred to as “recording / reproducing”) on a high-density optical disk using a blue-violet semiconductor laser having a wavelength of about 400 nm. Pickup devices have been developed and are already on the market. As an example of a high-density optical disc, an optical disc for recording / reproducing information with specifications of NA 0.8 to 0.95 and a light source wavelength 405 nm, so-called Blu-ray Disc (hereinafter referred to as BD), DVD (NA 0.6, light source wavelength). It is possible to record 25 GB of information per layer on an optical disk having a diameter of 12 cm, which is the same size as 650 nm and a storage capacity of 4.7 GB.

  By the way, it is preferable to mold the objective lens used in such an optical pickup device with a resin because mass production is possible at a low cost. However, since such an objective lens inherently has a high NA, desired optical characteristics are obtained. For this purpose, for example, it is necessary to accurately suppress the positional deviation of the optical surface. This is because, in the case of a BD objective lens having a large NA, the amount of coma generated when the optical surface is displaced is the same as that of the optical surface of the DVD or CD objective lens. This is because it is much larger than the amount of coma aberration generated in the above. For this reason, it is necessary to suppress the positional deviation of the optical surface with high accuracy, particularly in a BD objective lens having a large NA. On the other hand, Patent Document 1 discloses a molding apparatus that uses a taper bush and a taper guide to align the fixed side mold and the movable side mold, and thereby suppress the displacement of the transfer surface of the insert. .

JP-A-9-267362

According to the technique of Patent Document 1, the positional displacement of the nesting transfer surface is suppressed by using two or more pairs of the taper bush and the taper guide for alignment of the fixed side mold and the movable side mold. When a temperature difference between the fixed side mold and the movable side mold occurs, a difference in thermal expansion occurs, which causes a problem that the arrangement of the taper bush and the taper guide is shifted. As a result, there is a risk that two pairs of taper bushes and taper guides or one taper bush and taper guides cannot be fitted (also referred to as engagement). In addition, when a cylindrical or conical fitting member such as a taper bush is used, the taper fitting part is in contact with the line, the rigidity for positioning is inferior to the structure in which the surface is in contact, and the positioning accuracy decreases. is there. In particular, in the case of a cylindrical or conical fitting member, the accuracy of hole machining in the mold directly affects the fitting accuracy of the fitting member when it is incorporated into the die, so the position of the fitting member must be adjusted after installation. It is very difficult to fine tune. The combination of mating members is important for high-accuracy positioning, and it is necessary to align the mating direction. However, if the mating member has a cylindrical or conical shape, pay attention to the direction of rotation when assembling. There is a need. If a cylindrical or conical fitting member is used, the processing accuracy, assembly time, and processing cost of the fitting member will be increased. Furthermore, there is a demand for further reducing the cost by reducing the weight of the mold.
In addition, when the molds are closed with the fitting members being misaligned, one contact is caused, and if a high mold closing pressure is applied in this state, a large load is generated on the fitting members, and the fitting members themselves are affected. It will cause distortion. In particular, in the case of per line, the load is larger than that per surface. When a molded product that requires high transfer accuracy, such as an objective lens used in an optical pickup device, is injection molded with resin, a long holding time is required to improve transferability. As the length becomes longer, the distorted state becomes longer, resulting in a larger amount of distortion.

The present invention, while suppressing the number of processes and costs, and to provide a molding equipment which can allow the molding of high-precision lens.

Molding apparatus according to claim 1, in the molding apparatus for transferring molded lenses,
A first mold and a second mold each having a lens transfer surface and relatively movable;
A convex portion provided on one of the first mold and the second mold, and having an engagement plane;
A recess provided with an engagement plane provided on the other mold of the first mold and the second mold;
When the first mold and the second mold are clamped, the convex portion and the concave portion are engaged with each other by bringing the engaging plane into contact with each other, and the mold is formed along the engaging plane. The engagement position can be shifted in a direction orthogonal to the tightening direction.

  According to the present invention, since the positioning of the first mold and the second mold is performed by engaging the engagement planes of the concave portion and the convex portion, the positioning repeatability is good, Eccentricity between the lens molding surfaces of both molds can be effectively suppressed. Furthermore, since the concave portion and the convex portion can shift the engagement position in a direction orthogonal to the clamping direction along the engagement plane, the direction in which the mold thermally expands and the shiftable direction are aligned. Thus, the shift due to the temperature difference of the mold, that is, the shift due to the difference in thermal expansion can be suppressed without any load on the mold. Therefore, the present invention is particularly useful in the case of a BD lens having a large NA that needs to accurately suppress the positional deviation of the optical surface.

  Further, when the engaging portion is cylindrical or conical as in the prior art, a line hit is caused. However, since the convex portion and the concave portion make the engaging planes contact each other, the engaging portion comes into contact with each other. Increased rigidity. In the case of contact per surface compared to contact per line, the forcing force to eliminate the deviation between the fixed side mold and the movable side mold can be increased, so that the positioning accuracy can be improved. Further, since the load on the engaging portion can be reduced, the amount of wear is reduced, which is effective in extending the life of the engaging convex portion and the concave portion.

  Since the shift range of the convex portion to be engaged only needs to be wider than the thermal expansion difference, the engagement plane length in the shiftable direction of the convex portion does not have to pursue high accuracy, so the cost is reduced. Can be planned. In addition, the engaging concave portion similarly does not have to pursue high precision in the length of the engaging plane in the shiftable direction, so that the cost can be reduced. In other words, if the protrusions and the recesses are processed so that (the length of the engaging protrusions in the shiftable direction + the difference in thermal expansion <the length of the engaging recesses in the shiftable direction) is satisfied. It is possible to make play when assembling the mold, the convex part, and the concave part in the shiftable direction, and the part can be easily assembled. Therefore, processing accuracy and assembly time can be reduced.

In addition, when a molded product that requires high transfer accuracy, such as an objective lens used in an optical pickup device, is injection-molded with a resin, a long pressure holding time is required. In the present invention, as described above, since the concave portion and the convex portion can shift the engagement position in the direction perpendicular to the clamping direction along the engagement plane, the direction in which the mold thermally expands and the By aligning with the shiftable direction, it is possible to suppress the deviation due to the temperature difference of the mold, that is, the deviation due to the difference in thermal expansion without any load on the mold. Even if the mold can be closed without causing distortion and the pressure holding time becomes longer, there is no fear that the amount of distortion of the convex part and the concave part will increase. Thus, the present invention is also useful in injection molding that requires a long holding time.
As described above, as a result, according to the present invention, it is possible to manufacture a highly accurate BD lens with little coma aberration over a long period of time.

A molding apparatus according to a second aspect is characterized in that, in the invention according to the first aspect, the NA of the lens is 0.8 to 0.95.
The “lens with NA of 0.8 to 0.95” includes, for example, a BD, DVD and / or CD compatible lens in addition to a BD dedicated lens for an optical pickup device. The “engagement plane” does not necessarily need to be completely flat, and may have a recess in a part of the plane. For example, a groove for applying a lubricant such as grease may be provided. Further, “the convex portion and the concave portion engage with each other by bringing the engaging plane into contact with each other” is preferable.

According to a third aspect of the present invention, in the molding apparatus according to the first or second aspect, the first mold and the second mold include a lens transfer surface on a polygonal surface, and the convex portion. Is provided in the vicinity of the corner of the polygonal surface of the one mold, and the recess is provided in the vicinity of the corner of the polygonal surface of the other mold.

  By providing the convex portion and the concave portion in the vicinity of the corner of the polygonal surface of the mold, where unused space is often provided, such space can be used effectively. This can reduce the weight and reduce the cost. If the weight reduction of the mold is promoted, the part for holding the mold in the molding apparatus can be reduced in weight, and the inertial force of the movable part can be reduced and the addition can be reduced, so that the molding can be stably performed. The “polygonal surface” means a triangular surface or more, and particularly preferably a rectangular surface.

The molding apparatus according to claim 4 is the invention according to any one of claims 1 to 3 , wherein at least a portion of the convex portion and the concave portion to be engaged is perpendicular to a shiftable direction. It has a uniform shape along the direction. Thereby, stable engagement can be obtained regardless of the shift position.

  For example, in the manufacturing process of the convex part and the concave part, a convex bar material having a uniform cross section and being long in the direction in which the convex part is shifted, and a concave bar material having a uniform cross section and long in the direction in which the concave part is shifted, A plurality of the convex portions and the concave portions can be manufactured by cutting each required length, whereby the convex portions and the concave portions having the same engagement shape can be processed. For this reason, stable engagement can be realized.

According to a fifth aspect of the present invention, in the invention of the fourth aspect , the uniform shape is a rectangular shape. For example, when the lens to be molded has a diffractive structure having a micron-order fine shape, when the first mold and the second mold are opened after molding, the lens is orthogonal to the optical axis direction of the lens. Even a slight displacement may damage the diffractive structure formed on the optical surface of the lens. On the other hand, if the cross section of the convex part and the concave part perpendicular to the shiftable direction is rectangular, the first mold and the second mold can be changed to the lens by guiding on the side surface. The mold can be accurately opened along the optical axis direction.

According to a sixth aspect of the present invention, in the invention of the fourth aspect , the uniform shape is a trapezoidal shape. If it is such a shape, the said convex part and the said recessed part will be easy to engage at the time of mold clamping. The trapezoidal shape includes one whose one surface is parallel to the clamping direction.

A molding apparatus according to a seventh aspect is the invention according to any one of the first to sixth aspects, wherein the convex portion has a first convex block and a second convex block, and the concave portion is the first convex portion. A first concave block that engages with the convex block, and a second concave block that engages with the second convex block, and a shiftable direction between the first convex block and the first concave block is the first It is characterized by being orthogonal to the shiftable direction of the two convex blocks and the second concave block. Thus the shift along the two shiftable direction perpendicular is acceptable. Thus, the alignment direction can be forced using a plurality of pairs of blocks, and the rigidity of the engaging portion can be increased, and the alignment accuracy between the molds can be increased.

A molding apparatus according to an eighth aspect of the present invention is the invention according to any one of the first to seventh aspects, wherein the convex portion is a separate body from the one mold and is a recess formed in the one mold. And / or the recess is separate from the other mold and is attached to a recess formed in the other mold. By forming the mold or the concave portion separately from the mold, it can be formed with low cost and high accuracy. The “recess” is a recess provided in the mold, and includes a shape in which the peripheral surface is connected and a shape in which the peripheral surface is not connected. Of the “recesses”, the shape where the peripheral surfaces are connected is called a “hole”. There are “recesses” that penetrate the mold and those that do not penetrate. Further, the “indentation” is preferably a rectangular shape having directionality.

According to a ninth aspect of the present invention, in the invention of the eighth aspect , at least one of the convex portion and the concave portion is press-fitted into the recess. By press-fitting, the backlash between the molds can be eliminated, and high-precision molding can be performed.

According to a tenth aspect of the present invention, in the invention according to the eighth or ninth aspect , at least one of the convex portion and the concave portion is formed by combining block pieces having the same shape. .
When at least one of the convex part and the concave part is formed by combining block pieces having the same shape, that is, when a divided structure is used instead of an integrated structure, a forcing force to restore the deviation from the integrated structure is restored. It becomes possible to enlarge. For example, if there is only one block that forms a recess, the force is only for the block, but if the recess is formed from two block pieces, the mold will not be able to be separated even if the two block pieces that form the recess are separated from each other. forcing reed example Komutame mold acts large, hence when the divided structure, it becomes possible to increase the forcing.

The molding apparatus according to claim 1 1, characterized in that in the invention of any one of claims 8 to 10, wherein the recess and the convex portion, which are formed by combining the block pieces of the same shape And Since thereby formed using the same block piece and said concave portion and said convex portion, while low cost, can form protrusions and recesses of good compatibility with high accuracy.

The molding apparatus according to claim 1 2, in the invention of any one of claims 8-1 1, the thermal expansion coefficient of the convex portion is larger than the thermal expansion coefficient of the one mold, and In addition, the thermal expansion coefficient of the recess is larger than the thermal expansion coefficient of the other mold. As a result, at normal temperature, it is easy to assemble by providing a predetermined clearance between the indentation and the convex part or the concave part, and when the mold is heated and expanded at the time of molding, etc. At the same time, since the convex portion or the concave portion is heated and expanded more greatly in the recess, the clearance between the concave portion and the concave portion is reduced, so that the convex portion or the concave portion can be held more reliably. .

Forming apparatus according to claim 1 3 is the invention according to any one of claims 1 to 7, wherein the convex portion is integral with the one mold, and / or the recess said other mold It is characterized by being integral with. Thereby, the number of parts can be reduced. In addition, when forming a convex part in a metal mold | die, it can carry out using wire electric discharge machining.

Forming apparatus according to claim 1 4 is the invention according to any one of claims 1 to 1 3, at least one of the convex portion and the concave portion, characterized by applying a preload during mold clamping. Thereby, the shift function of the metal mold | die by the said convex part and the said recessed part is fully securable. “Applying preload” means that the convex portions and / or the concave portions are elastically deformed in the mold clamping direction to accumulate elastic force. For example, the convex portions and / or the concave portions are several. It is in a state of shrinking by about μm.

Forming apparatus according to claim 1 5, in the invention of any one of claims 1 to 1 4, shiftable direction and the convex portion and the concave portion, the first mold or the second It is characterized by being parallel to a radial line from the center of thermal expansion of the mold. This makes it possible to align the direction in which the convex portion and the concave portion can be shifted and the direction of thermal expansion of the first mold or the second mold in parallel. It is possible to reliably suppress the load without any load.

In the case of horizontal molding, the mold is likely to expand in the direction of gravity.For example, when a convex part and a concave part that can be shifted in the gravitational direction and a convex part and a concave part that can be shifted in a direction perpendicular to the gravitational direction are used, It is considered that the load applied to the convex part and the concave part that can be shifted in the direction orthogonal to the gravitational direction is larger than that in the gravitational direction. Here, the convex portion and the concave portion are provided in the vicinity of a corner portion of a quadrangular surface of the mold, and the shiftable direction between the convex portion and the concave portion is determined according to the first mold or the second mold. When parallel to the radial line from the center of thermal expansion of the mold, it is possible to equalize the load applied to each of the convex portions.
In the case where a plurality of convex portions are used, if the load applied to the respective convex portions is not uniform, it is considered that the degree of progress of wear varies, thereby reducing the positioning accuracy. On the other hand, if the load applied to each convex portion can be made uniform, the amount of wear can be reduced, and the progress of wear can be made uniform. Therefore, it is possible to extend the life of the convex portion and to increase the positioning accuracy.

Molding apparatus according to claim 1 6 is the invention according to any one of claims 1 to 1 5, wherein the lens is characterized by an objective lens for the optical pickup device.
The present invention is particularly useful when the lens requires high molding accuracy, such as an objective lens for an optical pickup device.

The molding apparatus according to claim 17 is characterized in that, in the invention according to any one of claims 1 to 16 , an optical path difference providing structure is formed on at least one optical surface of the lens. .
The “optical path difference providing structure” in this specification is a general term for structures that add an optical path difference to an incident light beam. The optical path difference providing structure also includes a phase difference providing structure for providing a phase difference. The phase difference providing structure includes a diffractive structure.
In the case of a lens formed with an optical path difference providing structure, in order to fill the structure with resin with good transferability, a longer holding time is required in molding. However, as described above, a lens that requires a long holding time. The present invention is also useful in the injection molding. Therefore, even a lens having an optical path difference providing structure can be molded with high accuracy.
In addition, in the case of a lens in which an optical path difference providing structure is formed, the allowable range with respect to the positional deviation of the optical surface becomes more severe, and the present invention is useful.

The molding apparatus according to claim 18 is the invention according to any one of claims 1 to 17 , wherein the lens has a maximum length in the optical axis direction of 4 mm or less and a direction orthogonal to the optical axis direction. The maximum length is 6 mm or less.
The present invention is useful because the smaller the lens size, the greater the influence of the displacement of the mold on the lens performance.

Forming apparatus according to claim 1 9, in the invention of any one of claims 1 to 1 8, characterized in the lens to satisfy the following expression.
0.8 ≦ d / f1 ≦ 1.5
However, d represents the thickness (mm) on the optical axis of the lens, and f1 represents the focal length (mm) of the lens in a light beam having a wavelength of 500 nm or less.
When dealing with an optical disk with a short wavelength and high NA such as BD, the objective lens has a problem that astigmatism easily occurs and coma aberration also easily occurs. Generation of point aberration and coma aberration can be suppressed. Therefore, according to the present invention, it is possible to provide a lens that has good astigmatism in addition to coma. In addition, when a thick lens that satisfies the above conditional expression is molded, a longer pressure holding time is required compared to a thin lens, but the present invention is also applied to a lens having a long pressure holding time as described above. Since it is useful, even a lens that satisfies the above conditional expression can be molded with high accuracy.

  According to still another aspect of the present invention, there is provided a molding apparatus for transferring and molding a lens having an NA of 0.8 to 0.95. Each of the molding apparatuses includes a lens transfer surface and a relatively movable first mold and first mold. Two molds, a convex portion provided on one of the first mold and the second mold and provided with an engagement plane; the first mold and the second mold; And having a concave portion provided with an engagement plane, and when the first mold and the second mold are clamped, the convex portion and the concave portion are The engagement planes are brought into contact with each other and engaged, and the engagement position can be shifted along the engagement plane extending in a direction orthogonal to the mold clamping direction.

  The molding method according to still another aspect of the present invention includes a first mold and a second mold, which are each provided with a lens transfer surface and are relatively movable, and the first mold and the second mold. A protrusion provided on one of the molds and having an engagement plane; and a recess provided on the other of the first mold and the second mold and having an engagement plane. When the first mold and the second mold are clamped, the convex portion and the concave portion are fitted with the engagement plane in contact with each other and orthogonal to the clamping direction. A lens having a NA of 0.8 to 0.95 is transferred and molded using a molding apparatus capable of shifting the fitting position in the direction along the engagement plane.

According to the present invention, while suppressing the number of processes and costs, it is possible to provide a molding equipment which can allow the molding of high-precision lens.

It is a one part perspective view of the shaping | molding apparatus which concerns on 1st Embodiment. It is an axial sectional view of a part of the molding apparatus according to the first embodiment. 5 is a diagram showing a part of the manufacturing process of the convex block 15 and the concave block 25. FIG. It is a figure which shows the dimensional relationship of the convex block 15 and the concave block 25. FIG. It is the figure which looked at the structure of FIG. 2 in the arrow V direction. It is a figure which shows the dimensional relationship of the convex block 15 and the concave block 25. FIG. It is a figure which shows the dimensional relationship of the convex block 15 and the concave block 25. FIG. FIG. 2 is an enlarged perspective view showing the relationship between the cutout portion and the escape portion, but is upside down from FIG. FIG. 2 is an enlarged perspective view showing the relationship between the cutout portion and the escape portion, but is upside down from FIG. It is a one part perspective view of the shaping | molding apparatus which concerns on 2nd Embodiment. It is a perspective view which shows a block piece. It is a perspective view which shows a block piece. It is a figure which shows the modification of a convex block and the concave block 25. FIG. It is a figure which shows the assembly modification which looked at the convex block and the concave block 25 in the shiftable direction. It is a figure which shows the assembly modification which looked at the convex block and the concave block 25 in the shiftable direction. It is sectional drawing of a part of the shaping | molding apparatus which concerns on 3rd Embodiment which performs the shaping | molding method of this invention. It is the fragmentary sectional view which cut | disconnected the structure of FIG. 15 by the arrow II-II line | wire, and looked at the arrow direction. It is the front view which cut | disconnected the structure of FIG. 15 by the arrow III-III line | wire, and looked at the arrow direction. It is a perspective view which shows a template and a block. It is a one part perspective view of the shaping | molding apparatus which concerns on 3rd Embodiment. It is a perspective view which shows a block piece. It is a perspective view which shows a block piece. FIG. 5 is a diagram showing a part of the manufacturing process of the convex block 25 and the concave block 13. It is a figure which shows the dimensional relationship of the convex block 25 and the concave block 13. FIG. It is a figure which shows the dimensional relationship of the convex block 25 and the concave block 13. FIG. It is a figure which shows the dimensional relationship of the convex block 25 and the concave block 13. FIG. It is an expansion perspective view which shows the relationship between a hole and an escape part. It is an expansion perspective view which shows the relationship between a hole and an escape part. It is a one part perspective view of the shaping | molding apparatus which concerns on 4th Embodiment. It is a figure which shows the modification of a convex block and a concave block. It is a figure which shows the assembly modification which looked at the convex block and the concave block in the shiftable direction. It is a figure which shows the assembly modification which looked at the convex block and the concave block in the shiftable direction. It is a partial cross section figure of the shaping | molding apparatus which concerns on 5th Embodiment. It is a fragmentary sectional view of the forming device concerning a 6th embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is a perspective view of a part of a molding apparatus according to a first embodiment for executing the molding method of the present invention. FIG. 2 is a sectional view in the axial direction of a part of the molding apparatus according to the first embodiment. 1 and 2, the mold clamping direction is the vertical direction, that is, the Z direction, and the mold clamping orthogonal direction is defined as the X direction and the Y direction. In FIG. 1, a fixed mold 10 as a first mold has a rectangular housing shape, is fixed to a frame (not shown), forms four transfer surfaces 12 on an upper surface 11, A notch 14 is formed so as to be exposed at each side surface 13. Each notch 14 is a rectangular parallelepiped recess having the same shape, and houses a convex block 15 therein. The thermal expansion coefficient of the convex block 15 forming the convex part is larger than the thermal expansion coefficient of the fixed mold 10. Each transfer surface 12 is connected to the central recess 17 via a radial runner path 16. Further, the rigidity of the convex block 15 is preferably larger than the rigidity of the fixed mold 10.

  On the other hand, the movable mold 20 as the second mold is similarly a rectangular casing, is fixed to a frame (not shown), and forms four transfer surfaces 22 (see FIG. 2) on the lower surface 21. In addition, a notch 24 is formed so as to be exposed on the lower surface 21 and each side surface 23. Each cutout 24 is a rectangular parallelepiped recess having the same shape and houses a concave block 25 therein. The thermal expansion coefficient of the concave block 25 that forms the concave part is larger than the thermal expansion coefficient of the movable mold 20. Each transfer surface 22 is connected to a sprue 27 penetrating the movable mold 20 through a radial runner path 26 so as to face the central recess 17. Further, the rigidity of the concave block 25 is preferably larger than the rigidity of the movable mold 20.

  FIG. 3 is a diagram illustrating a part of the manufacturing process of the convex block 15 and the concave block 25. When manufacturing the convex block 15, it can manufacture by forming the convex bar | burr material M15 with a uniform cross section of a longitudinal direction, and cutting this with a predetermined dimension. The convex block 15 is provided with a tapered portion 15c having a pair of inclined surfaces (engagement planes) 15a and a top surface 15b inclined in opposite directions on a rectangular parallelepiped.

  On the other hand, when manufacturing the concave block 25, it can manufacture by forming the concave bar material M25 with a uniform cross section of a longitudinal direction, and cutting this with a predetermined dimension. The concave block 25 forms a groove 25c having a pair of inclined surfaces (engagement planes) 25a and a bottom surface 25b inclined in opposite directions in a rectangular parallelepiped. The inner shape of the groove portion 25c substantially matches the outer shape of the tapered portion 15c. The inclination angle of the slope 15a of the convex block 15 and the inclination angle of the slope 25a of the concave block 25 may be the same angle or different angles. In the case of the same angle, the inclined surface 15a and the inclined surface 25a come into contact with each other uniformly, so that highly accurate positioning can be performed without causing unnecessary competition.

  The inner dimension of the notch 14 of the fixed mold 10 is slightly larger than the outer dimension of the convex block 15. Therefore, by assembling the shim SM, which is a thin plate material as an adjustment mechanism having an appropriate thickness, on the bottom surface and any one of the side surfaces of the notch portion 14, the convex block 15 is assembled to the notch portion 14, The taper portion 15c can be positioned in the mold clamping direction (Z direction) and in the direction orthogonal to the mold clamping direction (either the X direction or the Y direction). In the assembled state, the axis L1 (the center line of the taper portion 15c) of the two convex blocks 15 (here, the first convex block) facing each other across the transfer surface 12 coincides and extends in the Y direction. The axis L2 of the two convex blocks 15 (here, the second convex block) extends in the X direction perpendicular to the axis L1.

  Further, the inner dimension of the cutout 24 of the movable mold 20 is slightly larger than the outer dimension of the concave block 25. Accordingly, by assembling the shim SM, which is a thin plate material as an adjustment mechanism having an appropriate thickness, on the bottom surface and any one of the side surfaces of the notch portion 24, the concave block 25 is assembled to the notch portion 24. Positioning of the groove portion 25c in the mold clamping direction (Z direction) and the direction orthogonal to the mold clamping direction (either the X direction or the Y direction) can be performed. In the assembled state, the axis L3 (center line of the groove 25c) of the two concave blocks 25 facing each other across the transfer surface 22 coincides and extends in the Y direction, and the axis L4 of the other two concave blocks 25 extends. Extends in the X direction perpendicular to the axis L3.

  In addition, by using an adjustment mechanism (such as a shim), it is possible to make adjustments so as to eliminate deviations such as a height position when the convex block 15 and the concave block 25 are fitted. Moreover, since the shiftable direction may be rough positioning at that time, there is an advantage that adjustment is easy. Furthermore, since there is an adjustment mechanism, it is not necessary to obtain a high accuracy in the processing accuracy of the attaching portion of the convex block 15 and the concave block 25 to the mold. Therefore, processing accuracy and assembly time can be reduced.

Here, the dimensional relationship between the convex block 15 and the concave block 25 is as follows. Referring to FIG. 4, the dimension in the longitudinal direction (axis L1, L2 direction) of the groove 25c of the concave block 25 is a1, and the convex in the same direction. When the dimension of the block 15 is b1, and the dimension of the tapered portion 15c in the same direction is c1, it is preferable that the following expression is satisfied.
a1> b1 = c1

  In addition, when assembling the convex block 15 and the concave block 25 to the notches 14 and 24, the bolts can be fixed without using shims. In such a case, the upper surface 11 of the fixed mold 10 and the lower surface 21 of the movable mold 20 are in close contact with the convex block 15 and the concave block 25 being temporarily fixed, and the inclined surface 15a of the tapered portion 15c of the convex block 15 is secured. However, it may be adjusted and bolted so as to be in contact with the inclined surface 25a of the groove 25c of the concave block 25. In addition, even if the slope 15a of the convex block 15 and the slope 25a of the concave block 25 contact, the top surface 15b and the bottom face 25b do not contact.

  FIG. 11 is a perspective view showing a block piece according to a modification of the present embodiment. As shown in FIG. 11A, the block piece 125 has a substantially quadrangular prism shape in which the surfaces are orthogonal to each other, and includes a high upper surface 125a, a lower upper surface 125b that is parallel to the upper surface 125a and provided at a lower position, And an inclined slope 125c connecting the lower upper face 125b. Here, the width α of the high upper surface 125a and the width β of the lower upper surface 125b are equal (α = β). The high upper surface 125a is orthogonal to the long side surface 125d, and the low upper surface 125b is orthogonal to the short side surface 125e parallel to the long side surface 125d.

  As shown in FIG. 11B, when the same block piece 125 is combined with the long side surfaces 125d facing each other, the convex block 15 is formed. On the other hand, if the same block piece 125 is combined with the short side surfaces 125e facing each other, the concave block 25 is formed. A highly accurate block piece 125 having the same shape can be easily produced. Therefore, if the convex block 15 and the concave block 25 are formed by combining the block pieces 125, even if the inclination angle of the inclined surface 125c with respect to the high upper surface 125a is slightly deviated from the target angle (for example, 45 degrees), As long as there is no difference in the inclination angle of the slope 125c between the block pieces 125, the inclination angle of the slope 125c is uniform even in the combined state, and the slope of the convex block 15 and the slope of the concave block 25 are in uniform contact. Therefore, highly accurate positioning can be performed without causing unnecessary competition.

  Next, the operation of the present embodiment will be described. First, as shown in FIG. 1, the movable mold 20 is moved closer to the fixed mold 10 by a driving device (not shown) from the state where the movable mold 20 is separated from the fixed mold 10. Here, if the fixed-side mold 10 and the movable-side mold 20 are heated in advance by a heater (not shown), during normal temperature assembly, the notch 14 and the convex block 15 and the notch 24 and the concave block 25 are interposed between them. Even when a predetermined clearance is provided, the convex block 15 and the concave block 25 expand more greatly, and such clearance can be eliminated, thereby enabling highly accurate positioning.

  First, the inclined surface 15 a of the tapered portion 15 c of the convex block 15 is fitted so as to contact the inclined surface 25 a of the groove portion 25 c of the concave block 25, and the movable side mold 20 is fixed to the fixed side mold 10. Since it is guided to the position, the mold can be clamped so that the centers of the transfer surfaces 12 and 21 coincide with each other with high accuracy. Note that a preload may be applied to the tapered portion 15c during mold clamping. The positional deviation can be suppressed by increasing the rigidity of the tapered portion 15c. Usually, the taper portion 15c is adjusted so that it fits into the groove portion 25c at the position where the fixed die 10 and the movable die 20 are clamped, but the taper portion 15c is elastically deformed by several μm by the clamping force. It is preferable to adjust the fitting position in advance.

  After the mold clamping, the axis L1 overlaps with the axis L3, the axis L2 overlaps with the axis L4, and the inclined surfaces 15a and 25a extend in parallel thereto. The direction of the overlapping axis is defined as a shiftable direction. When the fixed side mold 10 and the movable side mold 20 are heated for molding and different expansions occur, as shown in FIG. 5, they are projected in the shiftable direction (that is, the X direction or the Y direction). The block 15 and the concave block 25 can be relatively shifted while maintaining the fitted state. However, since the thermal expansion difference is generally small, the center displacement of the transfer surfaces 12 and 22 can be ignored.

  In addition, it is preferable that the shiftable direction of the convex block 15 and the concave block 25 is parallel to the radial line from the center of thermal expansion of the fixed mold 10 or the movable mold 20. That is, the method of arranging the convex block 15 and the concave block 25 on the fixed side mold 10 and the movable side mold 20 is not limited to FIG. 1, and the shiftable direction and the radial line from the center of thermal expansion are What is necessary is just to arrange | position a convex block and a concave block so that it may become parallel. Here, the center of thermal expansion can be considered to be the center of the sprue 27 and the center of the central recess 17 as the center of thermal expansion.

  In the present embodiment, as shown in FIG. 1, four convex blocks 15 and four concave blocks 25 are used. However, the number of convex blocks and concave blocks is not limited to four. If the shiftable directions are not on the same straight line, two or more blocks can be used. Here, when the number of blocks is increased, the load on one block can be reduced, which is effective in extending the life of the blocks. On the other hand, when the number of blocks is reduced, the convex block and the concave block can be more smoothly fitted.

  Here, since the convex block 15 and the concave block 25 have a dimensional relationship such that a1> b1 = c1 with reference to FIG. 4, the convex block 15 and the concave block 25 are relatively moved in the shiftable direction. However, the taper portion 15c can be prevented from protruding from the groove portion 25c.

  After the lower surface 21 of the movable-side mold 20 is moved until it comes into close contact with the upper surface 11 of the fixed-side mold 10 and the mold is clamped, the sprue 27, the central recess 17, the runner path 16, After filling the resin formed in the cavity formed by the transfer surfaces 12 and 22 through 26 and solidifying, the movable mold 20 is separated from the fixed mold 10 as shown in FIG. Thus, an objective lens for an optical pickup device having NA = 0.85 to 0.95 can be molded.

  According to the present embodiment, since the positioning of the fixed side mold 10 and the movable side mold 20 is performed by fitting the convex block 15 and the concave block 25, the positioning repeatability is good, and both molds 10 , 20 can effectively suppress the eccentricity between the lens molding surfaces. Furthermore, since the convex block 15 and the concave block 25 can be shifted in the X direction or the Y direction while being fitted, by aligning the direction of thermal expansion of the molds 10, 20 and the shiftable direction, the mold 10, Deviation due to the temperature difference of 20, that is, deviation due to thermal expansion difference can be suppressed without any load on the mold.

  Further, according to the present embodiment, the slope 15a of the convex block 15 and the slope 25a of the concave block 25 are in contact with each other, thereby increasing the rigidity of the fitting portion and improving the positioning accuracy. In addition, since the load on the fitting portion can be reduced, there is an effect in extending the life of the fitting member.

  Since the shift range (a1-b1) of the convex block 15 is wider than the thermal expansion difference, the component length in the shiftable direction of the convex block 15 does not need to be highly accurate, so that the cost can be reduced. Similarly, the recessed block 25 to be fitted does not have to require high accuracy in the length of the component in the shiftable direction, so that the cost can be reduced. That is, referring to FIG. 4, the convex block 15 and the concave block 25 may be processed so that a1> b1 = c1, and the molds 10, 20 and the convex block 15 and the concave block 25 are assembled in the shiftable direction. It is possible to make time play, and assembling can be done easily. Therefore, processing accuracy and assembly time can be reduced.

FIG. 6 is a diagram showing a dimensional relationship between the convex block 15 and the concave block 25 according to a modification of the present embodiment. The dimensional relationship between the convex block 15 and the concave block 25 according to the modification is as follows. The longitudinal dimension of the groove 25c of the concave block 25 is a2, the dimension of the convex block 15 in the same direction is b2, and the tapered part in the same direction. When the dimension of 15c is c2, it is preferable that the following formula is satisfied.
a2 = b2> c2

FIG. 7 is a diagram illustrating a dimensional relationship between the convex block 15 and the concave block 25 according to another modification. The dimensional relationship between the convex block 15 and the concave block 25 according to the modification is as follows. The longitudinal dimension of the groove 25c of the concave block 25 is a3, the dimension of the convex block 15 in the same direction is b3, and the tapered part in the same direction. When the dimension of 15c is set to c3, it is preferable to satisfy | fill the following formula | equation.
a3>b3> c3

  However, the dimension in the longitudinal direction of the groove 25c of the concave block 25 may be made equal to the dimension of the convex block 15 in the same direction. In this case, it is desirable to provide a relief portion as shown in FIGS. More specifically, in the example of FIG. 8, a rectangular parallelepiped opening 24 ′ is formed as a recess in the lower surface 21 instead of the notch portion to which the concave block 25 is attached, and a wall between the opening 24 ′ and the side surface 23 is formed. A relief portion 28 is formed by cutting it into a rectangular shape. The bottom surface of the escape portion 28 is preferably flush with or deeper than the bottom surface 25b of the groove portion 25c of the concave block 25 (far from the lower surface 21). This example is effective when a convex block (not shown) of the same size shifts outward with respect to the concave block 25 due to thermal expansion between molds.

  On the other hand, in the example of FIG. 9, a rectangular parallelepiped opening 24 ′ is formed as a recess in the lower surface 21 instead of the notch for attaching the concave block 25, and the lower surface 21 opposite to the side surface 23 is further rectangularly sandwiched by the opening 24 ′. The escape portion 28 is formed by notching the shape. The bottom surface of the escape portion 28 is preferably flush with or deeper than the bottom surface 25b of the groove portion 25c of the concave block 25 (far from the lower surface 21). This example is effective when a convex block (not shown) of the same size shifts inward with respect to the concave block 25 due to thermal expansion between molds. The escape portion 28 may be provided on both sides of the opening 24 ′. In addition, when it is difficult to predict the difference in thermal expansion between the movable mold and the fixed mold, relief portions 28 may be provided at both ends of the concave portion, which is a combination of FIGS. .

[Second Embodiment]
FIG. 10 is a perspective view similar to FIG. 1 according to the second embodiment. In the present embodiment, the fixed side mold 10 ′ is integrally formed with a tapered portion 15c as a convex portion, and the movable side mold 20 ′ is integrally formed with a groove portion 25c as a concave portion. ing. In the present embodiment, the transfer surface 22 is formed on the end face of the insert C1, and the insert C1 is inserted into the opening 10a ′ of the fixed mold 10 ′. A transfer surface (not shown) opposite to the transfer surface 22 is formed on the end face of the insert C2, and the insert C2 is inserted into the opening 20a ′ of the movable mold 20 ′.

  In addition, the inserts C1 and C2 are not directly inserted into the openings of the molds 10 ′ and 20 ′, for example, reference numerals shown in FIGS. 1, 2, 5, and 6 of Japanese Patent Application Laid-Open No. 2004-168209. The insert may be inserted into the opening via a member such as 34,35. In this case, the number of balls of the rolling bearing is preferably about 50 to 200.

  Further, as shown in FIG. 10, a circular nesting C3 surrounding the entire transfer surface 22 may be provided in the circular opening 30a ′ of the fixed mold 10 ′. Similarly, a circular nesting C4 that surrounds the entire transfer surface (not shown) facing the transfer surface 22 may be provided in the opening 40a ′ of the movable mold 20 ′. Furthermore, the circular inserts C3 and C4 are not directly inserted into the circular openings of the molds 10 ′ and 20 ′, for example, FIG. 1, FIG. 2, FIG. 5, and FIG. A circular nest may be inserted into the circular opening via a member described as 34, 35 in the above. In this case, the number of balls of the rolling bearing is preferably about 50 to 200.

  FIG. 12 is a perspective view showing a convex block 15 ″ and a concave block 25 ″ according to a modification of the above-described embodiment. In the present embodiment, the concave block 25 ″ has a rectangular cross-sectional groove 25c ″ having a side surface 25a ″ and a bottom surface 25b ″ parallel to each other. That is, the cross section orthogonal to the shiftable direction is rectangular. On the other hand, the convex block 15 ″ has a projection 15c ″ having a side surface 15a ″ and a top surface 15b ″ parallel to each other. That is, the cross section orthogonal to the shiftable direction is rectangular. Such convex blocks 15 "and concave blocks 25" can be used in the same manner in the mold of the embodiment described above.

  At the time of molding, the protrusion 15c ″ fits into the rectangular cross-sectional groove 25c ″ while the side surface 15a ″ of the convex block 15 ″ slides with respect to the side surface 25a ″ of the concave block 25 ″. Thereby, positioning of metal mold | dies can be performed. When the mold is opened after molding, the side surfaces 15a "and 25" guide the mold so that the mold can be opened accurately along the optical axis direction of the molded lens. This is particularly effective when a diffractive structure is formed on the lens.

  For example, as shown in FIG. 13, the concave block 25 may be arranged so as to protrude from the lower surface 21 of the movable mold 20, or the concave block 25 may be disposed on the movable mold 20 as shown in FIG. 14. You may arrange | position so that it may draw in from the lower surface 21 to the back side. Note that a concave block may be provided on the fixed mold, and a convex block may be provided on the movable mold.

[Third Embodiment]
FIG. 15 is a partial cross-sectional view of a molding apparatus according to the third embodiment for executing the molding method of the present invention. 16 is a partial cross-sectional view of the configuration of FIG. 15 taken along the line II-II and viewed in the direction of the arrow. FIG. 17 is a front view of the configuration of FIG. 15 taken along line III-III and viewed in the direction of the arrow. FIG. 18 is a perspective view showing a template and a block. Although a horizontal molding apparatus is shown here, a vertical molding apparatus may be used. Here, the mold clamping direction is the Z direction, and the mold clamping orthogonal direction is the X direction and the Y direction.

  In FIG. 15, the fixed-side mounting plate 11A is fixed to a frame (not shown). On the left side of the fixed-side mounting plate 11A, a rectangular plate-shaped fixed-side template 12A is fixed by a bolt (not shown). Four rectangular holes 12aA (see FIG. 18) are formed through the rectangular surface 12tA of the fixed side template 12A, and a lens transfer surface 12bA is formed between the rectangular holes 12aA. . Each rectangular hole 12aA that can be formed by electric discharge machining or the like is disposed in the vicinity of the corner portion P1 of the fixed-side template 12A, and the center lines of the rectangular holes 12aA that are symmetrically disposed with respect to the center of the fixed-side template 12A are mutually connected. They overlap and pass through the corner P1 (see FIG. 17). Each transfer surface 12bA is connected to a sprue 12dA penetrating the fixed side mold plate 12A and the fixed side mounting plate 11A through a radial runner path 12cA.

  16 and 18, a concave block 13A is provided in each rectangular hole 12aA. Although the details will be described later, the concave block 13A is formed of two parts (block pieces to be described later), and each is fixed by screwing a bolt 15A inserted from the back side of the fixed side mounting plate 11A into the screw hole. Has been. However, both parts may be fixed to each other and one may be fixed with a single bolt. The thermal expansion coefficient of the concave block 13A that forms the concave is larger than the thermal expansion coefficient of the fixed-side template 12A. The fixed-side mold 10A is formed by the fixed-side mold plate 12A and the concave block 13A. Moreover, it is preferable that the rigidity factor of the concave block 13A is larger than the rigidity factor of the fixed side template 12A.

  On the other hand, the movable side attachment plate 21A is fixed to a drive unit (not shown). On the right side of the movable side mounting plate 21A, the spacer block 22A and the receiving plate 23A are fixed in this order. Further, on the right side of the receiving plate 23A, a rectangular plate-like movable side template 24A is provided by a bolt (not shown). It is fixed. Four rectangular holes 24aA (see FIG. 18) are formed through the rectangular surface 24tA of the movable side template 24A, and a lens transfer surface 24bA is formed between the rectangular holes 24aA. . Each rectangular hole 24aA that can be formed by electric discharge machining or the like is disposed in the vicinity of the corner P2 of the movable side mold plate 24A, and the center lines of the rectangular holes 24aA that are symmetrically disposed across the center of the movable side mold plate 24A are mutually connected. While overlapping, it passes through the corner P2. Each transfer surface 24bA is connected to the central recess 24dA via a radial runner path 24cA.

  16 and 18, a convex block 25A is provided in each rectangular hole 24aA. Although the details will be described later, the convex block 25A is formed of two parts (a block piece to be described later), and each has a height adjusting spacer 27A interposed by a bolt 26A inserted from the back side of the receiving plate 23A. While being screwed into the screw hole, it is fixed. However, both parts may be fixed to each other and one may be fixed with a single bolt. The thermal expansion coefficient of the convex block 25A forming the convex part is larger than the thermal expansion coefficient of the movable side template 24A. The movable side mounting plate 21A, the spacer block 22A, the receiving plate 23A, the movable side mold plate 24A, and the convex block 25A are moved integrally. The movable mold 20A is formed by the movable mold 24A and the convex block 25A. Further, it is preferable that the rigidity of the convex block 25A is larger than the rigidity of the movable mold 20A.

  Note that a height adjusting spacer may be provided in the rectangular hole 12aA formed in the fixed side template 12A. Further, a spacer for adjusting the position of the concave block 13A or the convex block 25A with respect to the direction orthogonal to the shiftable direction may be provided in each rectangular hole 12aA, 24aA, or in a direction parallel to the shiftable direction. A spacer for adjusting the position may be provided. As described above, by using a position adjusting mechanism such as a spacer in each of the rectangular holes 12aA and 24aA, adjustment can be performed so as to eliminate a shift in the height position or the like when the concave block 13A and the convex block 25A are engaged. it can. At this time, since the shiftable direction may be rough positioning, there is an advantage that adjustment is easy. Furthermore, since there is an adjusting mechanism, the processing accuracy of the rectangular holes 12aA and 24aA formed in the fixed side mold plate 12A and the movable side template 24A does not need to be high. Therefore, processing accuracy and assembly time can be reduced.

  Referring to FIG. 18, in the assembled state, the axis L1A of two convex blocks 25A (here, the first convex block) facing each other across the center of the movable side template 24A coincides with each other in the X direction. The axis L2A of the other two convex blocks 25 (here, the second convex block) extends and extends in the Y direction that is orthogonal to the X direction. Further, in the assembled state, the axis L3A of the two concave blocks 13A (here, the first concave block) facing each other across the center of the fixed side template 12A coincides and extends in the X direction, and another The axis L4A of the two concave blocks 13A (here, the second concave block) coincides and extends in the Y direction orthogonal to the X direction.

  FIG. 19 is a perspective view showing a block piece constituting the convex block and the concave block of the present embodiment. As shown in FIG. 19A, the block piece 125 has a substantially quadrangular prism shape in which the surfaces are orthogonal to each other, and includes a high upper surface 125aA, a lower upper surface 125bA that is parallel to the upper surface 125aA and provided at a lower position, and a higher upper surface 125aA. And an inclined surface 125cA connecting the low upper surface 125bA. Here, the width αA of the high upper surface 125aA and the width βA of the lower upper surface 125bA are equal (αA = βA). The high upper surface 125aA is orthogonal to the long side surface 125dA, and the low upper surface 125bA is orthogonal to the short side surface 125eA parallel to the long side surface 125dA.

  As shown in FIG. 19B, when the same block piece 125A is combined with the long side surfaces 125dA facing each other, a convex block 25A is formed. On the other hand, if the same block piece 125A is combined with the short side faces 125eA facing each other, the concave block 13A is formed. A highly accurate block piece 125A having the same shape can be easily produced. Therefore, if this block piece 125A is combined to form the convex block 25A and the concave block 13A, even if the inclination angle of the inclined surface 125cA with respect to the high upper surface 125aA is slightly deviated from the target angle (for example, 45 degrees), As long as there is no difference in the inclination angle of the inclined surface 125cA between the block pieces 125A, the inclined angle of the inclined surface 125cA is uniform even in the combined state, and the inclined surface of the convex block 25A and the inclined surface of the concave block 13A are in uniform contact. Therefore, highly accurate positioning can be performed without causing unnecessary competition.

  The convex block 25A and the concave block 13A can be formed from a single unit. FIG. 20 is a diagram illustrating a part of the manufacturing process of the convex block 25A and the concave block 13A according to the modification. When manufacturing the convex block 25A concerning a modification, it can manufacture by forming the convex bar material M25A with a uniform cross section of a longitudinal direction, and cutting this with a predetermined dimension. The convex block 25A is provided with a tapered portion 25cA having a pair of inclined surfaces (engagement planes) 25aA and a top surface 25bA inclined in opposite directions on a rectangular parallelepiped. When such a block piece 125A is used in a molding apparatus as shown in FIGS. 15 to 17, 16 block pieces 125A are used.

  On the other hand, when manufacturing the concave block 13A, it can be manufactured by forming the concave bar M13A having a uniform cross section in the longitudinal direction and cutting it with a predetermined dimension. The recessed block 13A forms a groove 13cA having a pair of inclined surfaces (engagement planes) 13aA and a bottom surface 13bA inclined in opposite directions in a rectangular parallelepiped. The inner shape of the groove 13cA substantially matches the outer shape of the tapered portion 25cA. The inclination angle of the slope 25aA of the convex block 25A and the inclination angle of the slope 13aA of the concave block 13A may be the same angle or different angles. When the angles are the same, the inclined surface 25aA and the inclined surface 13aA come into contact with each other uniformly, and therefore, highly accurate positioning can be performed without causing unnecessary competition.

Here, the dimensional relationship between the convex block 25A and the concave block 13A is as follows. Referring to FIG. 21, the dimension of the groove 13cA of the concave block 13A in the longitudinal direction (axis L3, L4 direction) is a1A. When the dimension of the block 25A is b1A and the dimension of the tapered portion 25cA in the same direction is c1A, it is preferable that the following expression is satisfied.
a1A> b1A = c1A

  This dimensional relationship can also be applied to the case where the convex block 25A or the concave block 13A is composed of a plurality of block pieces (the same applies to the following modified examples). In addition, even if the slope 25aA of the convex block 25A and the slope 13aA of the concave block 13A are in contact, the top surface 25bA and the bottom surface 13bA are not in contact with each other.

  Next, the operation of the present embodiment will be described. First, as shown in FIGS. 15 and 16, the movable mold 20 </ b> A is moved closer to the fixed mold 10 </ b> A from the state in which the movable mold 20 </ b> A is separated by a driving device (not shown). Here, if the fixed side mold 10A and the movable side mold 20A are heated in advance by a heater (not shown), during assembly at room temperature, the rectangular hole 24aA and the convex block 25A and the rectangular hole 12aA and the concave block 13A are interposed. Even when a predetermined clearance is provided, the convex block 25A and the concave block 13A expand more greatly, and the clearance can be eliminated, thereby enabling highly accurate positioning.

  Here, first, the inclined surface 25aA of the tapered portion 25cA of the convex block 25A is engaged with the inclined surface 13aA of the groove portion 13cA of the concave block 13A, and the movable side die 20A is fixed to the fixed side die 10A. Since the position is guided, the mold can be clamped so that the centers of the transfer surfaces 25bA and 13bA coincide with each other with high accuracy. At this time, since a preload is applied to the tapered portion 25cA during mold clamping, the taper portion 25cA contracts due to elastic deformation. Further, the rigidity of the tapered portion 25cA can be increased to suppress the positional deviation. Normally, the taper portion 25cA is adjusted to engage with the groove portion 13cA at the position where the fixed side mold 10A and the movable side die 20A are clamped, but in advance, the taper portion 25cA is elastically deformed by several μm by preload. It is preferable to adjust the engagement position.

  After clamping, the axis L1A overlaps with the axis L3A, the axis L2A overlaps with the axis L4A, and the inclined surfaces 25aA and 13aA extend in parallel thereto. The direction of the overlapping axis is defined as a shiftable direction. When the fixed side mold 10A and the movable side mold 20A are heated for molding and different expansions occur, as shown in FIG. 17, it is convex in the shiftable direction (that is, the X direction or the Y direction). The block 25A and the concave block 13A can be relatively shifted while maintaining the engaged state. However, since the thermal expansion difference is generally small, the center displacement of the transfer surfaces 25bA and 12bA can be ignored.

  In addition, it is preferable that the shiftable direction of the convex block 25A and the concave block 13A is parallel to the radial line from the center of thermal expansion of the fixed mold 10A or the movable mold 20A. That is, the method of arranging the convex block 25A and the concave block 13A on the fixed mold 10A and the movable mold 20A is not limited to FIG. 15, and the shiftable direction and the radial line from the center of thermal expansion are as follows. What is necessary is just to arrange | position a convex block and a concave block so that it may become parallel. Here, the center of thermal expansion can be considered as the center of thermal expansion by the center of the sprue 12dA or the center of the central recess 24dA.

  In this embodiment, as shown in FIG. 15, four convex blocks 25A and four concave blocks 13A are used. However, the number of convex blocks and concave blocks is not limited to four. The shape may be a polygon, and a plurality of blocks may be provided in accordance with the corners. Here, when the number of blocks is increased, the load on one block can be reduced, which is effective in extending the life of the blocks. On the other hand, when the number of blocks is reduced, the engagement between the convex blocks and the concave blocks can be performed more smoothly.

  Here, since the convex block 25A and the concave block 13A have a dimensional relationship such that a1A> b1A = c1A with reference to FIG. 21, the convex block 25A and the concave block 13A move relative to each other in the shiftable direction. However, it is possible to avoid the taper portion 25cA from protruding from the groove portion 13cA.

  After moving the movable mold 20A until the surface of the movable mold 20A comes into close contact with the fixed mold 10A and clamping the mold, a sprue 12dA, a central recess 24dA, runner paths 12cA, 14cA are supplied from a supply source (not shown). Then, after filling the resin formed in the cavity formed by the transfer surfaces 12bA and 24bA and solidifying it, as shown in FIG. 15, the movable mold 20A is separated from the fixed mold 10A. An objective lens for an optical pickup device with NA = 0.85 to 0.95 can be molded.

  According to the present embodiment, the fixed mold 10A and the movable mold 20A are aligned by engaging the convex block 25A and the concave block 13A, so that the positioning repeatability is good and both molds 10A are aligned. , 20A can effectively suppress the eccentricity of the lens molding surfaces. Further, since the convex block 25A and the concave block 13A can be shifted in the X direction or the Y direction while being engaged, the mold 10A, 20A can be shifted by aligning the direction of thermal expansion of the mold 10A, 20A with the shiftable direction. Deviation due to the temperature difference of 20A, that is, deviation due to thermal expansion difference can be suppressed without any load on the mold.

  Further, according to the present embodiment, the slope 25aA of the convex block 25A and the slope 13aA of the concave block 13A are in contact with each other, thereby increasing the rigidity of the engaging portion and improving the positioning accuracy. In addition, since the load on the engaging portion can be reduced, it is effective in extending the life of the engaging member.

  Since the shift range (a1A-b1A) of the convex block 25A is wider than the thermal expansion difference, the component length in the shiftable direction of the convex block 25A does not need to be highly accurate, so that the cost can be reduced. Similarly, the concave block 13A to be engaged does not have to require high precision in the length of the component in the shiftable direction, so that the cost can be reduced. That is, referring to FIG. 21, the convex block 25A and the concave block 13A may be processed so that a1A> b1A = c1A, and the molds 10A and 20A, the convex block 25A, and the concave block 13A are assembled in the shiftable direction. It is possible to make time play, and assembling can be done easily. Therefore, processing accuracy and assembly time can be reduced.

  In addition, by providing the convex block 25A and the concave block 13A near the corners P1 and P2 of the rectangular surfaces of the molds 10A and 20A, the unused space can be used effectively. It can be made more compact, thereby reducing weight and cost. If the weight reduction of the molds 10A and 20A is promoted, the part for holding the mold in the molding apparatus can be reduced in weight, and the inertial force of the movable part can be reduced and the addition can be reduced, so that the molding can be stably performed. . Furthermore, since the convex block 25A and the concave block 13A are inserted into the holes 24aA and 12aA of the template plates 24A and 12A, respectively, deformation in the opening direction that may occur, for example, when inserted into the notch can be suppressed, and high accuracy is achieved. Can be molded.

FIG. 22 is a diagram showing a dimensional relationship between the convex block 25A and the concave block 13A according to the modification of the present embodiment. The dimensional relationship between the convex block 25A and the concave block 13A according to the modified example is that the longitudinal dimension of the groove 13cA of the concave block 13A is a2A, the dimension of the convex block 25A in the same direction is b2A, and the tapered part in the same direction. When the dimension of 25 cA is c2A, it is preferable that the following formula is satisfied.
a2A = b2A> c2A

FIG. 23 is a diagram illustrating a dimensional relationship between a convex block 25A and a concave block 13A according to another modification. The dimensional relationship between the convex block 25A and the concave block 13A according to the modified example is that the longitudinal dimension of the groove 13cA of the concave block 13A is a3A, the dimension of the convex block 25A in the same direction is b3A, and the tapered part in the same direction. When the size of 25 cA is c3A, it is preferable that the following formula is satisfied.
a3A>b3A> c3A

  However, the dimension in the longitudinal direction of the groove 13cA of the concave block 13A may be equal to the dimension of the convex block 25A in the same direction. In this case, it is desirable to provide a relief portion as shown in FIGS. 24 and 25 in the mold provided with the concave block 13A. More specifically, in the example of FIG. 24, adjacent to the outside of the hole 12aA to which the concave block 13A is attached, the relief portion 12bA is formed by cutting out into a rectangular parallelepiped shape. The bottom surface of the escape portion 12bA is preferably flush with or deeper than the bottom surface 13bA of the groove portion 13cA of the concave block 13A (far from the convex block 25A). This example is effective when a convex block (not shown) of the same size is shifted outward with respect to the concave block 13A due to thermal expansion between molds. Further, the escape portion 12bA may be formed so as to penetrate out of the mold. In other words, the escape portion 12bA may be formed so as to be exposed on the side surface of the template.

  On the other hand, in the example of FIG. 25, adjacent to the inside of the hole 12aA to which the recessed block 13A is attached, the relief portion 12bA is formed by cutting out into a rectangular parallelepiped shape. The bottom surface of the escape portion 12bA is preferably flush with or deeper than the bottom surface 13bA of the groove portion 13cA of the concave block 13A (far from the convex block 25A). This example is effective when a convex block (not shown) of the same size is shifted inward with respect to the concave block 13A due to thermal expansion between the molds. The escape portion 12bA may be provided on both sides of the hole 12aA. When it is difficult to predict the difference in thermal expansion between the movable side mold and the fixed side mold, relief portions 12bA may be provided at both ends of the concave portion, which is a combination of FIGS. .

[Fourth Embodiment]
FIG. 26 is a perspective view similar to FIG. 18 according to the fourth embodiment. In the present embodiment, the fixed side mold 10′A is integrally formed with a tapered groove (not shown) as a concave portion, and the movable side mold 20′A is a tapered portion 25cA as a convex portion. Is integrally molded. In the present embodiment, the movable transfer surface 24bA is formed on the end surface of the cylindrical insert C1A, and the insert C1A is fitted in the opening 24fA of the movable mold plate 24A. On the other hand, a transfer surface (not shown) opposite to the transfer surface 24bA is formed on the end face of the cylindrical insert C2A, and the insert C2A is inserted into the opening 12fA of the fixed side template 12A.

  The inserts C1A and C2A are not directly inserted into the openings of the molds 10′A and 20′A, for example, FIG. 1, FIG. 2, FIG. 5, FIG. The insert may be inserted into the opening through a member described as 34, 35. In this case, the number of balls of the rolling bearing is preferably about 50 to 200.

  Further, as shown in FIG. 26, a circular nesting C3A surrounding the entire transfer surface 24bA may be provided in the circular opening 24gA of the movable side mold plate 24A. Similarly, a circular nesting C4A that surrounds the entire transfer surface (not shown) facing the transfer surface 24bA may be provided in the opening 12gA of the stationary-side template 12A. Furthermore, the circular inserts C3A and C4A are not directly inserted into the circular openings of the molds 10′A and 20′A, for example, FIG. 1, FIG. 2, FIG. A circular nesting may be inserted into the circular opening through a member described as reference numerals 34 and 35 in FIG. In this case, the number of balls of the rolling bearing is preferably about 50 to 200.

  FIG. 27 is a perspective view showing a convex block 25 "A and a concave block 13" A according to a modification of the above-described embodiment. In the present embodiment, the concave block 13 ″ A has a rectangular cross-sectional groove 13c ″ A having a side surface 13a ″ A and a bottom surface 13b ″ A that are parallel to each other. That is, the cross section orthogonal to the shiftable direction is rectangular. On the other hand, the convex block 25 ″ A has a protrusion 25c ″ A having a side surface 25a ″ A and a top surface 25b ″ A that are parallel to each other. That is, the cross section orthogonal to the shiftable direction is rectangular. The convex block 25 "A and the concave block 13" A can be similarly used in the mold according to the above-described embodiment.

  At the time of molding, the side surface 25a "A of the convex block 25" A slides with respect to the side surface 13a "A of the concave block 13" A, and the protrusion 25c "A engages (fits) with the rectangular cross-sectional groove 13c" A. ) Thereby, positioning of metal mold | dies can be performed. When opening the mold after molding, the side surfaces 25a "A, 13a" A guide the mold so that the mold can be opened with high precision along the optical axis direction of the molded lens. This is particularly effective when a diffractive structure is formed on the lens.

  For example, as shown in FIG. 28, the concave block 13A may be arranged so as to protrude from the surface of the movable mold 20A, or as shown in FIG. 29, the concave block 13A is arranged on the surface of the movable mold 20A. You may arrange | position so that it may draw in from the back side. Furthermore, it is desirable to provide chamfered portions TP at the insertion ends of the convex blocks 25A and the concave blocks 13A that are press-fitted into the holes 24aA and 12aA of the templates 24A and 12A, or at the edges of the holes 24aA and 12aA. When a chamfered portion is provided on one side, a straight portion slightly narrower than the width of the other side is preferably provided on the end portion or the edge portion. Note that a concave block may be provided on the fixed mold, and a convex block may be provided on the movable mold.

[Fifth Embodiment]
FIG. 30 is a cross-sectional view similar to FIG. 16 of the molding apparatus according to the fifth embodiment. In the embodiment shown in FIG. 30, the convex block 25A is provided on the fixed side, the concave block 13A is provided on the movable side, and the receiving plate 23A and the concave block 13A are disposed in the hole 24aA of the movable side mold plate 24A. In addition to providing a spacer 27A therebetween, a spacer 14A is also disposed between the fixed side mounting plate 11A and the convex block 25A in the hole 12aA of the fixed side template 12A. Thereby, more detailed positioning becomes possible. Note that the spacer 14A may be disposed only between the fixed-side mounting plate 11A and the concave block 13A.

[Sixth Embodiment]
FIG. 31 is a cross-sectional view similar to FIG. 16 of the molding apparatus according to the sixth embodiment. In the embodiment shown in FIG. 31, a single convex block 25A and concave block 13A are used. For this, the convex block 25A and the concave block 13A manufactured by the manufacturing method shown in FIG. 20 can be used. Only one of the convex block 25A and the concave block 13A may be a single unit.

  It describes below about the corner | angular part vicinity of the polygonal surface in this specification. When the polygonal surface is a regular polygonal surface, the area included in each circle when a circle with a radius of 0.60A centered on each vertex is drawn, where A is the length of one side. Is called near the corner of the polygonal surface. If the polygonal surface is not a regular polygonal surface, the length of the longer side of the two sides forming one vertex is A ′, and a circle with a radius of 0.60 A ′ centered on that vertex When each is drawn at each vertex, the region included in the circumference is called the vicinity of the corner of the polygonal surface.

10, 10 'fixed side mold 11 upper surface 12 transfer surface 13 side surface 14 notch 15 convex block 15a "side surface 15a slope 15b top surface 15c" taper portion 15c "projection 16 runner path 17 central recess 20, 20' movable side mold 21 Lower surface 22 Transfer surface 23 Side surface 24 Notch portion 24 Opening 25 Concave block 25a "Side surface 25a Slope 25b Bottom surface 25c Groove portion 25c" Rectangular section groove 26 Runner path 27 Sprue 28 Escape portion 125 Block piece C1, C2 Nesting M15 Convex rod M25 Concave rod Material SM Shim 10A Fixed side mold 11A Fixed side mounting plate 12A Fixed side mold plate 12aA Rectangular hole 12bA Transfer surface 12cA Runner path 12dA Sprue 12fA Opening 12gA Opening 13A Concave block 13a "A Side surface 13aA Slope 13bA, 13" A Bottom surface 13cA Groove 14A Spacer 15A Bolt 20A Movable Side mold 21A Movable side mounting plate 22A Spacer block 23A Receiving plate 24A Movable side plate 24aA Rectangular hole 24bA Transfer surface 24cA Runner path 24dA Central recess 24fA Opening 24gA Circular opening 25A Convex block 25a "A Side surface 25aA Slope 25bA, 25" A Top surface 25cA Tapered portion 25c "A Protrusion 26A Bolt 27A Spacer 125A Block piece 125aA High upper surface 125bA Low upper surface 125cA Slope 125dA Long side surface 125eA Short side surface C1A, C2A Nesting C3A, C4A Nesting M13A Concave rod material M25A Convex bar material TP Chamfer

Claims (19)

In a molding device for transfer molding a lens,
A first mold and a second mold each having a lens transfer surface and relatively movable;
A convex portion provided on one of the first mold and the second mold and provided with an engagement plane;
A recess provided on the other of the first mold and the second mold and provided with an engagement plane;
When the first mold and the second mold are clamped, the convex portion and the concave portion are fitted with the engagement plane in contact with each other in a direction perpendicular to the clamping direction. A molding apparatus characterized in that the fitting position can be shifted along the extending engagement plane.   The molding apparatus according to claim 1, wherein the lens has an NA of 0.8 to 0.95. The first mold and the second mold include a lens transfer surface on a polygonal surface,
The convex portion is provided in the vicinity of a corner portion of the polygonal surface of the one mold,
The molding apparatus according to claim 1, wherein the concave portion is provided in the vicinity of a corner portion of a polygonal surface of the other mold.   The at least a portion of the convex portion and the concave portion to be fitted has a cross section orthogonal to the shiftable direction having a uniform shape along the shiftable direction. The molding apparatus as described.   The molding apparatus according to claim 4, wherein the uniform shape is a rectangular shape.   The molding apparatus according to claim 4, wherein the uniform shape is a trapezoidal shape.   The convex portion has a first convex block and a second convex block, and the concave portion is a first concave block that engages with the first convex block, and a second concave that engages with the second convex block. The shiftable direction of the first convex block and the first concave block is orthogonal to the shiftable direction of the second convex block and the second concave block. The shaping | molding apparatus in any one of 1-6.   The convex part is separate from the one mold, and is attached to a recess formed in the one mold, and / or the concave part is separate from the other mold, The molding apparatus according to claim 1, wherein the molding apparatus is attached to a recess formed in the other mold.   The molding apparatus according to claim 8, wherein at least one of the convex portion and the concave portion is press-fitted into the recess.   The molding apparatus according to claim 8 or 9, wherein at least one of the convex portion and the concave portion is formed by combining block pieces having the same shape. The said convex part and the said recessed part are each formed combining the block piece of the said same shape, The shaping | molding apparatus in any one of Claims 8-10 characterized by the above-mentioned.   The thermal expansion coefficient of the convex portion is larger than the thermal expansion coefficient of the one mold, and / or the thermal expansion coefficient of the concave portion is larger than the thermal expansion coefficient of the other mold. The molding apparatus according to any one of claims 8 to 11.   The molding apparatus according to claim 1, wherein the convex portion is integral with the one mold and / or the concave portion is integral with the other mold.   The molding apparatus according to claim 1, wherein a preload is applied to at least one of the convex portion and the concave portion during mold clamping.   The shiftable direction between the convex portion and the concave portion is parallel to a radial line from the thermal expansion center of the first mold or the second mold. The molding apparatus in any one of.   The molding apparatus according to claim 1, wherein the lens is an objective lens for an optical pickup device.   The molding apparatus according to claim 1, wherein an optical path difference providing structure is formed on at least one optical surface of the lens.   18. The molding according to claim 1, wherein the lens has a maximum length in the optical axis direction of 4 mm or less and a maximum length in a direction orthogonal to the optical axis direction of 6 mm or less. apparatus. The molding apparatus according to claim 1, wherein the lens satisfies the following expression.
0.8 ≦ d / f1 ≦ 1.5
However, d represents the thickness (mm) on the optical axis of the lens, and f1 represents the focal length (mm) of the lens in a light beam having a wavelength of 500 nm or less.

Images