JP5275707B2 - Injection molding apparatus and molded product take-out method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin lens, injection-molding apparatus, and method of ejecting molded article in which the resin lens can be released from a mold without sacrificing an optical property in injection molding of the resin lens. <P>SOLUTION: A molded article 10 having a product part 2 to be a resin lens 1 held in a movable mold 8 when opening the mold, is ejected by ejection pins 71, 72, 73, and an insert mold 50 having a surface for forming the product part 2. The ejection pin 71 pushes a part to be pushed 6 connected to the product part 2 of the molded article 10. The ejection pin 72 pushes a runner part 4 of the molded article 10, and the ejection pin 73 pushes a sprue part 5 of the molded article 10. After the molded article 10 is ejected from the movable mold 8, the product part 2 is released from the insert mold 50 by operating the ejection pins 71, 72, 73 in a state where the insert mold 50 is stopped. In this case, the product part 2 is in a state where pushed from both of the runner part 4 and the part to be pushed 6. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to an injection molding apparatus capable of maintaining an optical shape suitable for required optical characteristics and preventing optical characteristics from deteriorating due to generation of strain based on a force acting upon release from a mold. The present invention relates to a method for taking out a molded product .

  In recent years, for example, a resin lens made of a thermoplastic resin has been used as an objective lens used in an optical pickup device for reading and writing of an optical disk such as a Blu-ray disc, DVD, or CD, instead of a glass mold lens. Such an objective lens is molded by injection molding.

Such an objective lens made of resin is composed of an optical function part (lens part) that functions as an optical element and a flange part that is formed around the periphery of the optical function part. The flange portion is used for positioning and fixing when the objective lens is attached to the optical pickup device.
In the injection molding of the objective lens, the injection mold includes, for example, a movable mold (first mold) and a fixed mold (second mold), and the movable mold opens and closes with respect to the fixed mold. Operate. Then, after the injection molding, the movable mold is moved to the open side with respect to the fixed mold of the injection mold to open the mold, and the molded product is taken out from the injection mold. In general, the shape of the molded product is designed so that the molded product remains on the movable mold side when the mold is opened. After the mold is opened, the molded product is taken out from the movable mold.

  That is, it is necessary to take out a molded product remaining in one mold (movable mold) after opening the mold. When taking out, for example, the part that forms the objective lens of the movable mold is a nest, and the part can be moved into and out of the movable mold main body. A method of taking out from a mold is known (for example, refer to Patent Documents 1 and 2).

The mold is provided with a cavity for molding the objective lens, and a sprue and runner for supplying resin to the cavity. The resin injected into the sprue passes through the runner toward the cavity and enters the cavity. Will be filled. Further, a mold forming surface serving as a cavity is formed on the tip surface of the insert. The tip connected to the cavity of the runner is narrower in diameter than the rear part, and this part is generally called a gate. The gate is a part of the runner that supplies resin to the cavity. Become.
Corresponding to the structure of the mold, the molded product is connected to the product part that is molded in the cavity and becomes the objective lens, the runner part that is connected to the product part and formed by the runner, and the runner part And a sprue portion formed by the sprue.
The tip of the runner portion is formed by the gate as a part of the runner, and the runner portion includes the gate portion.

And the said nest | insert pushes out a product part and takes out a molded article from a metal mold | die.
Further, in the injection molding, the molded product is taken out from the mold by using an eject pin (extrusion member) for extruding the molded product instead of pushing out the molded product by nesting as described above.
The eject pin pushes not the product part but the runner part in the vicinity of the product part so as not to damage the product part when molding an optical component, for example. The part closest to the product part in the runner part is the gate part, but in extremely small products such as the objective lens of an optical pickup, the gate part is small in diameter and fragile and difficult to push out with an eject pin. Usually, a portion having a large diameter is pressed with an eject pin on the rear side of the gate portion of the runner portion.

  In the injection molding of optical parts, when the product part is extruded directly with an eject pin, the entire product part is extruded as described above with a nest having a formation surface of the product part so that the product part is not damaged. Thus, when the product portion is pushed out by the above-described nesting, the nesting functions as an eject pin.

  In addition, in the objective lens of the optical pickup device, for example, two or more Blu-ray discs, DVDs and CDs having different laser wavelengths and different distances to the focal point can be used together, In order to be able to cope with a change in the refractive index due to an influence or the like, it is known that a lens is provided with a ring zone as a fine stepped surface (see, for example, Patent Document 3).

  Further, there is known one in which a concave portion along the circumference is formed between the optical function portion of the objective lens and the flange portion (for example, see Patent Document 4). That is, in such an objective lens, the thickness of the outer flange portion of the convex optical function portion on the surface on the light source side is thicker than the thickness of the outer peripheral edge portion of the optical function portion. Since the flange portion is higher in the thickness direction than the outer peripheral edge portion, a recess is formed in the boundary portion from the optical function surface to the flange surface.

Japanese Patent Laid-Open No. 2002-200508 JP 2004-130703 A Japanese Patent Laid-Open No. 2002-200652 Japanese Patent Laid-Open No. 2002-200654

By the way, the objective lens of the conventional optical pickup device for DVD has an aperture ratio (numerical aperture NA) of about 0.6, whereas the aperture ratio of the objective lens of the optical pickup device for Blu-ray disc is about 0.85. ing.
For this reason, an objective lens having a condensing function as an optical function for Blu-ray has a convex shape curved with a smaller radius of curvature than that of an objective lens for DVD. For example, a surface facing the light source (a surface facing the optical disc) The inclination of the tangential line orthogonal to the circumferential direction in the outermost peripheral part of the optical function part on the opposite side) is about 75 degrees with respect to the plane orthogonal to the optical axis.

In addition, the inclination with respect to the plane orthogonal to the optical axis of the tangent line along the direction orthogonal to the circumferential direction of the optical function portion is greatest at the outermost peripheral portion.
Moreover, in the objective lens for DVD, for example, the inclination of the tangent line along the direction orthogonal to the circumferential direction at the outermost peripheral portion of the optical function portion is about 60 degrees.
In the objective lens, the radius of curvature of the lens surface facing the optical disc is large, while the radius of curvature of the lens surface facing the light source (in which light from the light source is incident) is small. Therefore, the objective lens has a shape that protrudes greatly toward the light source side.
In injection molding, the smaller the radius of curvature, the wider the contact surface between the mold and the molded product, the higher the resistance in the take-out direction per unit area, and the harder the mold release. Therefore, it is generally set so that the surface on the light source side with a small radius of curvature that is difficult to release from the objective lens faces the movable mold side, and when the mold is opened, the surface on the light source side with a small radius of curvature is the movable mold. To be left in.

In addition, since the lens having a smaller radius of curvature as described above is less likely to be released, the Blu-ray disc objective lens is less likely to be released than the DVD objective lens.
In addition, as described above, when there is an annular recess between the optical function portion and the flange portion of the objective lens, or there is a ring zone in the objective lens, and the optical function surface has a fine concave shape due to the ring zone. When the concave portion is formed, the objective lens as a molded product is difficult to release. The mold for forming the annular recess as described above has an annular projection that enters the annular recess.

  This is because when the thermoplastic resin is molded and cured while being cooled from the molten state during injection molding, the thermoplastic resin contracts due to a decrease in temperature. At this time, the molded product is contracted in a state where the annular convex portion of the mold enters the annular concave portion of the molded product, and the annular shape of the molded product is compared with the annular convex portion of the mold. The recess of the diameter is reduced. As a result, the outer peripheral side of the inner surface of the annular concave portion of the molded product is pressed so as to clamp the outer peripheral side of the outer surface of the annular convex portion of the mold, and the mold release such as friction between these surfaces that are in contact with each other Resistance force against will be generated. Note that even if the concave portion of the molded product or the convex portion of the mold is not annular, if the convex portion of the mold enters the concave portion of the molded product, one of them will be formed on the inner surface of the concave portion and the outer surface of the convex portion. A pressing force due to contraction of the molded product acts between the portions, and a resistance force to the mold release occurs.

  Therefore, even if the molded product is pushed out from the movable mold by the insert for forming the product portion that becomes the objective lens as in the conventional case, the product portion may not be smoothly taken out from the insert. That is, even if the insert for molding the product portion is pushed out, no force acts on the product portion in the mold release direction, so that the product portion remains attached to the insert and it becomes difficult to smoothly take out the molded product.

  When the product part that becomes the objective lens is released from the movable mold by pushing the runner part with the eject pin, if the objective lens has the structure as described above, a large resistance acts, and the product part is smoothly moved. It cannot be released. In particular, since the gate part between the product part and the runner part has a small diameter and a weak structure, when the runner part is pushed to release the product part, the diameter of the runner part with a narrow diameter is reduced. There is a possibility that the gate portion which is the tip portion is bent.

When the gate part is bent in some molded products and the molded product is deformed, when the objective lens is separated from the product part by cutting the gate part in the post-molding process, Since the shapes do not match, it becomes difficult to automatically cut the gate portion, and there is a risk of hindering the post-molding process.
In addition, distortion occurs in the molded product when the gate part bends, but if this distortion reaches the objective lens that is the product part, the optical characteristics of the objective lens may deteriorate due to this distortion. There is a risk of lowering performance and yield.

  The present invention has been made in view of the above circumstances, and even if it is a resin lens that is difficult to release after injection molding, such as an objective lens for a Blu-ray disc, it is reliable without deteriorating the optical characteristics of the resin lens. It is another object of the present invention to provide an injection molding apparatus, a method for taking out a molded product, and a lens that can be released smoothly.

In order to achieve the object, an injection molding apparatus according to claim 1 is a mold including a first mold and a second mold that are opened, and a molded product that is held when the mold is opened. An injection molding apparatus for molding a resin lens, comprising a mold release unit that is provided in one mold and releases a molded product from the first mold.
The mold includes a cavity for molding a product part to be a resin lens, a runner connected to the cavity and supplying resin to the cavity, and connected to the cavity and supplied with resin through the cavity. One pressed shape forming part,
The mold release means has a forming surface to be a cavity of a first mold, and a insert for extruding a product part molded by the cavity of the molded product from the first mold,
A runner extruding member for extruding a runner portion formed by the runner of the molded product from the first mold;
Including at least one pressed portion pushing member that pushes out the pressed portion formed by the pressed shape forming portion of the molded product from the first mold,
The mold release means is configured to advance the insert, the runner extruding member, and the pressed member extruding member at substantially the same moving speed and extrude the molded product from the first mold, and then release the mold.
By changing the moving speed of the nest and the moving speeds of the runner push-out member and the pressed portion extruding material so as to be relatively different while the nest is moved without being stopped , the runner The product portion of the molded product is pushed out from the insert and released from the mold by setting the insert relatively backward with respect to the push member and the pressed member push member.

  In the first aspect of the present invention, when the molded product having the product portion that becomes the resin lens is released from the mold that is opened, the insert that molds the product portion and the runner that pushes out the runner portion A release part and a pressed part extrusion member that extrudes a pressed part that is formed by supplying resin from the product part for release, and releasing the molded article smoothly by releasing the molded article can do.

  Here, by operating the insert, the runner pushing member, and the pressed member, the molded product can be smoothly released from the mold excluding the insert. The product part in which a relatively large resistance force may act upon releasing from the insert is formed by, for example, operating the runner push member and the pressed part push member against the insert. After taking out the whole from a 1st metal mold | die, the product part of a molded product can be taken out from a nest | insert with a runner extrusion member and a to-be-pressed part extrusion member.

  At this time, the runner portion can be extruded at a plurality of locations of the runner portion of the molded product and at least one pressed portion by a plurality of extruded members of the runner push member and at least one pressed portion push member. The stress is not concentrated only on the gate portion connected to the product portion at the end of the runner portion as in the case of pushing only the gate portion, and the gate portion can be prevented from bending.

And, by preventing the gate portion from bending, in the subsequent process, when the gate portion and the pressed portion are cut from the product portion, a molded product having a bent gate portion is mixed, thereby reducing workability. It is possible to smoothly cut the gate part and the pressed part from the product part.
In addition, distortion occurs in the molded product when the gate part bends, but this distortion reaches the product part and deteriorates the optical characteristics of the resin lens by preventing the gate part from bending as described above. Can be prevented.
In addition, for example, even when a large resistance occurs when the product part is released from the surface where the insert is formed due to the shape of the product part that becomes a resin lens, the product part is reliably and smoothly released from the insert. It becomes possible.

  In addition, with respect to the product portion, the portions pressed by the extrusion members of the runner portion and the pressed portion need not overlap in the mold release direction of the molded product, and the runner portion and the pressed portion are And extending in a direction substantially perpendicular to the mold release direction.

Further , after the insert, the runner pushing member, and the pressed portion pushing member are advanced at substantially the same moving speed at the same time to extrude the molded product from the first mold and release the mold, By changing the moving speed and the moving speed of the runner push-out member and the pressed portion extrusion material so as to be relatively different, the nesting moves backward relative to the runner push-out member and the pressed portion push-out member. By setting it as a state, the said product part of the said molded product can be extruded from the said nest | insert, and can be released.
For example, the operations after releasing the molded product from the first mold include the following.

That is, the runner extruding member and the pressed portion extruding member remain at the moving speed when the molded product is released from the first mold, and the nest moving speed is released from the first mold. It will decelerate from the moving speed. At this time, nesting may be stopped. Furthermore, the moving direction of the nesting may be reversed. In other words, the moving speed of the nest may be negative. By setting it as the above moving speeds, a nest | retreating retracts relatively with respect to a runner extrusion member and a to-be-pressed part extrusion member.
Alternatively, the runner extruding member and the pressed portion extruding member increase the moving speed from the moving speed when the molded product is released from the first mold, and the nest is kept at the same speed or decelerated.

Or after a runner pushing member, a to-be-pressed part pushing member, and a nest | stop are stopped, only a nest | insert may be moved to a reverse direction.
Even these way, relatively nesting is retracted relative to the runner pushing member and the pushed portion pusher member.
Even if it is other than the above-mentioned case, it is relatively nested with respect to the runner extruding member and the pressed portion pushing member so that the nest is retracted relatively with respect to the runner pushing member and the pushed portion pushing member. Any speed may be used as long as the speed is reduced. At this time, any of the movement speeds of the runner pushing member, the pressed member pushing member, and the insert may be 0 or may be minus (reverse direction).

  Also, when the product part is released from the insert, the part other than the product part of the molded product is already released, so when the product part is released from the insert, It is not affected by the state of mold release of the molded product. In other words, when it is assumed that the entire molded product including the product part is released at the same time, if a part of the molded product is delayed in release, stress may be concentrated on the product part and the gate part. There is sex. However, in this invention, since parts other than the product part of a molded product are released from the first mold before releasing the product part from the insert, the product part can be released smoothly.

An injection molding apparatus according to claim 2 is the invention according to claim 1 ,
The resin lens has a convex shape having a light collecting function,
In the portion corresponding to the outermost peripheral portion of the optical functional surface having the optical function of the resin lens, the nest forming surface is molded with respect to a plane perpendicular to the optical axis direction of the resin lens. The tangent perpendicular to the circumferential direction of the resin lens is 65 degrees or more and 85 degrees or less.

In a second aspect of the present invention, in a portion corresponding to the outermost peripheral portion of the optical functional surface having the optical function of the resin lens, the surface of the insert is formed in the optical axis direction of the resin lens. A tangent line orthogonal to the circumferential direction of the resin lens molded with respect to an orthogonal plane (a plane orthogonal to the mold release direction for releasing the molded product from the first mold) is 65 degrees or more and 85 degrees or less. Therefore, it is possible to mold a product part to be a resin lens with a small radius of curvature, and even this causes a relatively large resistance to be generated when the product part is released from the forming surface of the insert. Since the product part can be reliably and smoothly released by extruding the runner part, the product part, and the pressed part as described above, for example, for molding a resin lens having a high aperture ratio such as an objective lens for a Blu-ray disc. Also use It is possible.
The angle is preferably 70 degrees or more and 80 degrees or less, and as an objective lens for a Blu-ray disc, the angle is preferably about 75 degrees (for example, 73 to 77 degrees). .
Moreover, when the said angle becomes 85 degree | times or more, there exists a possibility that mold release may become difficult.

Moreover, in the invention according to claim 1 or claim 2, the injection molding device according to claim 3 is provided with a convex portion that faces the molded product along the mold release direction on the surface of the insert. It is provided.

In the invention according to claim 3 , an annular recess is formed at the boundary between the optical function portion and the flange portion of the resin lens by providing a convex portion toward the molded product along the mold release direction. Or an optical function part can be provided, and even if the resistance when releasing the product part from the insert is increased, the runner part and the product part are By extruding the pressed part with certainty, the product part can be reliably and smoothly released. For example, in the objective lens for Blu-ray Disc, the optical characteristics based on the shape by providing the concave part and the ring zone are reliably expressed. Can be made.
In other words, it is possible to manufacture a resin lens having an annular recess without sacrificing optical characteristics in order to obtain a shape that is easy to release.

According to a fourth aspect of the present invention, when the resin lens is injection-molded with a mold having a first mold and a second mold that are opened, the molded product is held when the mold is opened. 1. A molded product release method for releasing a molded product from a mold,
The injection mold includes a cavity that molds a product portion that becomes a resin lens, a runner that is connected to the cavity and supplies resin to the cavity, and is connected to the cavity and supplied with resin through the cavity. And at least one pressed shape forming part.
In addition, the first mold has a forming surface to be a cavity of the first mold, an insert for extruding a product portion formed by the cavity of the molded product from the first mold, and the molded product At least one of the runner pushing member that pushes out the runner portion formed by the runner from the first mold and the pressed portion formed by the pressed shape forming portion of the molded product from the first die. Two pressed parts pushing member,
During mold opening operation or after mold opening, the molded product is pushed out from the first mold by the insert, the runner pushing member, the pressed portion extrusion material, and the molded product is released from the mold,
After the nest, the runner push member, and the pressed portion push member are advanced at the same moving speed at the same time to extrude the molded product from the first mold and release the mold,
By changing the moving speed of the nest and the moving speeds of the runner push-out member and the pressed portion extruding material so as to be relatively different while the nest is moved without being stopped , the runner The product portion of the molded product is pushed out from the insert and released from the mold by setting the insert relatively backward with respect to the push member and the pressed member push member.

In the invention according to claim 4 , the same effect as that of the invention according to claim 1 can be obtained.

The resin lens is an injection molded resin lens,
A mold used for injection molding that opens into a first mold and a second mold includes a cavity for molding a product portion to be the resin lens, and a runner that is connected to the cavity and supplies resin to the cavity. And at least one pressed shape forming part connected to the cavity and supplied with resin through the cavity,
The molded product molded by the mold includes at least one pressed part formed by the product part molded by the cavity to be a resin lens, the runner part formed by the runner, and the pressed shape forming part. With
When the mold is opened, the entire product part, the runner part, and the pressed part are pushed out of the mold from the first mold that holds the molded product, thereby releasing the molded product.
A runner cutting part that cuts the runner part by cutting the runner part and the pressed part from the product part of the molded product, and a pressed cutting part that cuts the pressed part. Have

  The resin lens is a resin lens having required optical characteristics and having no distortion in the optical function portion having an optical function.

In the resin lens, the tangent angle orthogonal to the circumferential direction at the outermost peripheral portion of the convex optical functional surface having a light collecting function is 65 degrees or more and 85 degrees or less with respect to the plane orthogonal to the optical axis. ing.

The resin lens is a resin lens suitable as an objective lens of an optical pickup device for a Blu-ray disc.

The resin lens includes an optical function part having an optical function and a flange part formed around the optical function part, and an optical function of a surface to be held by the first mold An annular recess is formed in the boundary portion between the first portion and the flange portion along the mold release direction from the first mold.

According to the resin lens, there is no structure in which an annular recess is not provided in order to facilitate release, and the optical function part is distorted at the time of release by providing the annular recess. Therefore, it is possible to obtain a resin lens having an optimum structure that satisfies the required optical specification.

The resin lens includes an optical functional surface having an optical function,
An annular zone is formed on the optical functional surface held by the first mold, and an annular recess is formed by the annular zone in a state of being recessed from the first mold along the releasing direction. It is characterized by that.

According to the resin lens, it is not necessary to eliminate the annular zone in order to facilitate mold release, or to change the annular zone to a structure that does not allow a concave structure, and the optical characteristics required by the annular zone are achieved. It can be set as the resin lens of the optimal structure to satisfy.

  According to the present invention, when a resin lens having a high aperture ratio used for an objective lens of an optical pickup device for a Blu-ray disc is injection-molded and released, it can be reliably and smoothly released. It is possible to prevent a situation in which distortion occurs in the resin lens during molding and the optical characteristics deteriorate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a molded product that is a resin lens of the present embodiment, that is, a molded product that is molded by the injection molding apparatus of this example and is released by the molded product extraction method of this example will be described. 1 and 2 show the entire molded product, FIGS. 3 and 4 are enlarged views of main parts of the molded product, and FIGS. 5 and 6 show a resin lens (product part) separated from the molded product. It is.
As shown in FIGS. 1 to 6, this molded product 10 becomes, for example, a resin lens 1 used as an objective lens of an optical pickup device for a Blu-ray disc, and a mold (movable mold 8, fixed mold 9). : Product part 2 formed by cavity 2a in FIG. 10 and subsequent figures), gate part 3 formed by mold gate 3a described later, runner part 4 formed by mold runner 4a, A sprue portion 5 formed by a sprue 5a of a mold and a pressed portion 6 formed by a pressed shape forming portion 6a of a mold are provided. The gate 3a is a part of the runner 4a, and the gate part 3a is a part of the runner part 4a and is included in the runner part 4a.

In molding, for example, a thermoplastic resin (hereinafter abbreviated as resin) is injected to the base end side of the sprue 5a, and the resin flows from the sprue 5a to the runner 4a, passes through the gate 3a of the runner 4a, and then cavities. 2a is filled with resin. Further, the resin overflows from the cavity 2a and fills the pressed shape forming portion 6a.
Therefore, the runner portion 4 is connected to the tip of the sprue portion 5, the product portion 2 is connected to the gate portion 3 of the runner portion 4, and the pressed portion 6 is connected to the product portion 2.

Further, in this example, four resin lenses 1 are taken from one molded article 10, and in a direction perpendicular to the axial direction of the sprue part 5 from the tip part of the sprue part 5 and radially in four directions. A runner portion 4 is formed to extend. And the product part 2 is connected to the front-end | tip of the gate part 3 which is the front-end | tip part of the runner part 4. FIG. Further, in this example, each product part 2 is provided with a pressed part 6, and the pressed part 6 is arranged on an extension line of the shaft of the runner part 4, and the pressed part 6 and the runner part 4 is in a state of being opposed to the gate portion 3 at the tip of 4 with the product portion 2 interposed therebetween.
The pressed part 6 includes a circular part 62 that is pressed by an eject pin 71 described later, and a connection part 61 that connects the circular part 62 and the product part 2.

Here, the connecting portion 61 of the pressed portion 6 and the connecting portion of the product portion 2 and the connecting portion of the runner portion 4 and the gate portion 3 and the product portion have cross-sectional shapes similar to each other and cross-sectional areas similar to each other. It has become. The same shape and the same area may be used. In this way, when the above-mentioned two connecting portions have substantially the same cross-sectional shape and substantially the same cross-sectional area, when the pressed portion 6 and the runner portion 4 are pressed almost uniformly by the eject pins 71 and 72, either It is possible to prevent stress from concentrating on one connecting portion and to press in a balanced manner, and to more reliably prevent the gate portion 3 from bending at the time of mold release.
The mold is composed of a movable mold 8 and a fixed mold 9 that are opened as will be described later. The boundary between the movable mold 8 and the fixed mold 9 is arranged on the substantially central axis of the runner portion 4. It has become so.
The base end side of the sprue portion 5 where the resin is injected is disposed in the fixed mold 9, and the distal end portion of the sprue section 5 is disposed on the movable mold 8 side beyond the runner portion 4.

The sprue part 5 is longer on the fixed mold 9 side to which the resin is supplied than the movable mold 8 side and is on a truncated cone that is long in the axial direction. On the side, the circumference is formed in a columnar shape with almost no inclination, and the diameter is larger than that of the fixed mold 9.
Further, the gate part 3, the product part 2 and the pressed part 6 are formed on the movable mold 8 side from the center line part of the runner part 4. That is, the gate part 3, the product part 2, and the pressed part 6 are arranged so as to be biased toward the movable mold 8 side from the boundary portion between the movable mold 8 and the fixed mold 9.

Further, a columnar protrusion 41 (runner lock) is formed on the movable side from the center between the sprue portion 5 and the gate portion 3 of the rod-like runner portion 4 toward the movable side.
Thus, on the movable mold 8 side of the molded product, half of the runner part 4, the protrusion 41 of the runner part 4, the thick cylindrical part of the sprue part 5, the gate part 3, the pressed part 6 and the product part 2 Thus, the molded product 10 remains in the movable mold 8 when the mold is opened as described later.

Then, as shown in FIGS. 3 to 6, the product portion 2 to be the resin lens 1 has an optical function in which light (laser) actually passes and has an optical function (in this example, condensing), as shown in FIGS. Part 11 and a flange part 12 provided around the optical function part 11 in a bowl shape and positioned and fixed to the optical pickup device.
In the optical pickup device, the optical function unit 11 includes a first optical functional surface 13 that is irradiated with light from the light source side, and a second optical functional surface 14 that faces the optical disc.
And the focal position of condensing exists in the front side of the 2nd optical functional surface 14, and the light which injects from the 1st optical functional surface 13 and radiate | emits the 2nd optical functional surface 14 is condensed. Become.

  As shown in FIG. 5, the first optical functional surface 13 has a small curvature radius and a large curved shape, and has a convex shape that protrudes greatly in the optical axis direction from the outer peripheral portion toward the central portion. ing. On the other hand, the second optical functional surface 14 has a large curvature radius, a slightly curved and gently convex shape, and slightly protrudes in the optical axis direction from the outer peripheral portion toward the central portion. ing.

  And the angle of the tangent line orthogonal to the circumferential direction in the outermost peripheral part (boundary part with the flange part 12) of the 1st optical functional surface 13 with a small curvature radius of the optical function part 11 of the resin lens 1 is, for example, light It is set to 75 degrees with respect to a plane orthogonal to the axial direction. In other words, the angle between the direction of releasing the resin lens 1 from the movable mold 8 parallel to the optical axis of the resin lens 1 and the plane perpendicular to the moving direction of the movable mold 8 relative to the fixed mold 9 is 75 degrees. It has become. This is the shape of the objective lens of an optical pickup device for a Blu-ray disc having an aperture ratio of about 0.85. For example, in the objective lens of an optical pickup device for DVD having an aperture ratio of about 0.6, The angle of the tangent along the circumferential direction of the outer periphery is about 60 degrees.

That is, the resin lens 1 of this example is formed so as to be usable as an objective lens of a Blu-ray disc, and for this reason, the angle of the tangent is large.
In this example, the first optical functional surface 13 side faces the movable mold 8 side, and the first optical functional surface 13 forms a later-described insert 50 forming surface 51 of the movable mold 8 when the mold is opened. It is in a state attached to.
In addition, due to the injection molding apparatus and the molded product taking-out method, even when the angle is 65 to 85 degrees, a stress is applied to the resin lens 1 at the time of mold release to cause distortion and a decrease in optical characteristics. The resin lens of this example is suitable as an objective lens for a Blu-ray disc.

Further, in the resin lens 1 of the present invention, on the first optical functional surface 13 side, that is, on the movable mold 8 side, an annular shape along the circumferential direction is formed at the boundary portion between the optical functional portion 11 and the flange portion 12. A recess 15 is formed.
In the resin lens 1 of the present invention, a plurality of annular zones 16 and 17 are formed on the first optical functional surface 13. Here, the annular zones 16 and 17 have different shapes on the central side and the outer peripheral side of the first optical functional surface 13. Here, the general basic shape of the annular zones 16 and 17 is along the convex surface (first optical functional surface 13) of the resin lens 1 when viewed in a cross section along the diameter direction of the resin lens 1. However, the inclination of the portion that contacts the step board between the steps is different between the annular zone 16 on the central side and the annular zone 17 on the outer peripheral side.

  That is, in the annular zone 16 on the central side, the slope where the tread plate portion falls from the inner peripheral side to the outer peripheral side of the convex surface of the resin lens 1 (the slope in the direction approaching the parting line between the fixed mold 9 and the movable mold 8). It has become. As a result, there is no structure that is recessed in the optical axis direction. On the other hand, in the annular zone 17 on the outer peripheral side, the portion that contacts the tread of the staircase is an inclined surface (an inclined surface in a direction away from the parting line) that rises from the inner peripheral side toward the outer peripheral side. Thereby, in the annular zone 17, each stepped step portion has an annular fine protrusion structure, and an annular fine recess is provided adjacent to the inner peripheral side of the protrusion. .

That is, since the first optical functional surface 13 is basically a convex surface, it becomes a slope inclined downward from the center side toward the outer peripheral side. There is a portion that slopes up as it goes to, and a concave structure is formed between the slope that slopes down and the slope that slopes up adjacent to the outer periphery.
These concave structures change the optical characteristics of the resin lens, and the design of the lens varies depending on whether these structures are formed or not. In the case of a structure necessary for realizing a functional function, for example, if these structures are modified in order to improve the releasability, that is, if the structure is such that the concave portion is eliminated, the optical characteristics are somewhat deteriorated. There is a possibility, and in some cases, it may be a marginal requirement or may not satisfy the requirement.

Further, the product part 2 to be the resin lens 1 is connected to the gate part 3 and the pressed part 6. In the resin lens 1 taken out from the molded product 10 as shown in FIG. Thus, the first cutting portion 18 (gate cutting portion) and the second cutting portion 19 (pressed cutting portion) obtained by cutting the base end portion of the pressed portion 6 are formed.
Here, the pressed portion 6 becomes a portion pressed by the eject pin 71 for the pressed portion 6 when the molded product 10 is taken out from the movable mold 8 that opens the mold. In this example, when the molded product 10 is released from the movable mold 8, the insert 50 provided with the forming surface 51 that constitutes the movable mold 8 side of the cavity 2 a and the pressed portion 6 are pressed. The molded product 10 is pushed out by an eject pin 71 as a pressing portion pushing member and an eject pin 72 as a runner pushing member that pushes the columnar protrusion 41 of the runner portion 4.
As shown in FIG. 10 and the like, the movable mold 8 is further provided with an eject pin 73 that presses the tip of the sprue portion 5.

Moreover, the to-be-pressed part 6 provided in the product part 2 is not restricted to one, Two or more two or more may be sufficient. For example, when there are two pressed parts 6, two eject pins 71 that press the pressed part 6 are also provided.
Further, as shown in the modification of this example in FIG. 7, when there are two pressed parts 6, the resin lens 1 has one and two first pressed parts 18 that cut the gate part 3 described above. Two second cut portions 19 obtained by cutting the portion 6 are formed.

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In FIG. 7, one first cutting portion 18 and two second cutting portions 19, 19 are arranged with a substantially equal interval. That is, one first cutting part 18 and two second cutting parts 19, 19 are arranged symmetrically. Here, the space | interval of the two 2nd cutting parts 19 and 19 (two pressed parts 6) is narrowed, and the 1st cutting part 18 and each 2nd cutting | disconnection from the space | interval of these 2nd cutting parts 19 and 19 mutually. You may lengthen the space | interval to a part. At this time, in the resin lens 1, the two second cut portions 19 and 19 are symmetrical with respect to a plane along the optical axis direction that passes through the center of the left and right of the gate 18 and the center of the resin lens 1. It is preferable to arrange | position.

Thereby, when the 1st cutting part 18 is used for positioning etc. at the time of attachment of the resin lens 1, it becomes possible to distinguish the 1st cutting part 18 and the 2nd cutting parts 19 and 19 easily. Further, at this time, for example, the angle formed by the first cutting section 18 and the second cutting section 19 is set to about 1.5 times or more than the angle formed by the two second cutting sections 19, 19. Thus, the first cutting part 18 and the second cutting part 19 can be easily distinguished even by appearance.
In addition, in the resin lens 1 shown in FIG. 7, it becomes the same structure as the resin lens 1 shown in FIG.5 and FIG.6 except the structure where the 2nd cutting part 19 is provided two instead of one (plurality). Yes.

FIG. 8 and FIG. 9 are modifications of the resin lens 1 (product part 2) of this example, in which the annular zones 16 and 17 are not provided. In the case where the ring zones 16 and 17 are not provided, it becomes difficult to cope with a change in the bending rate due to a temperature change and a plurality of wavelengths and a plurality of focal lengths. For example, an optical pickup device for a Blu-ray disc It can be used as an objective lens.
The resin lens 1 shown in FIGS. 8 and 9 has the same configuration as the resin lens 1 of this example shown in FIGS. 5 and 6 except that the annular zones 16 and 17 are not provided.
Although not shown, the resin lens 1 shown in FIGS. 5 to 9 may have a configuration in which the concave portion 15 is not provided between the optical function portion 11 and the flange portion 12.

That is, in the resin lens 1, the second cutting portion 19 (the pressed portion 6 in the molded product 10) may be one or more than two, or may not be provided as the configuration in which the annular zones 16 and 17 are provided. It is good also as a structure which does not provide as a structure which provides the recessed part 15, or may provide.
However, in the injection molding apparatus and the method for taking out the molded product of the present invention, it is possible to deal with the molded product 10 having the resin lens 1 (product part 2) that is more difficult to release, and the annular zones 16 and 17 and the concave portions. 15 and the resin lens 1 shown in FIGS. 5 and 6, which will be difficult to release as described later, and the resin lens 1 shown in FIG. 7.
In addition, when it is difficult to release the mold, a resin lens having a plurality of second cut portions 19 due to a plurality of pressed portions 6 is preferable.
In addition, the resin lens 1 is made of a thermoplastic resin in this example, but the composition of the thermoplastic resin is determined in accordance with the optical characteristics, and any composition of the thermoplastic resin is used. Also good.

Next, the injection molding apparatus of the present invention will be described.
As shown in FIGS. 10 to 13, the basic structure of the injection molding apparatus is such that the mold has a movable mold 8 and a fixed mold 9 as in the prior art.
In order to form the molded product 10, the mold is formed with a sprue 5a, a runner 4a (including the gate 3a) cavity 2a, and a pressed shape forming portion 6a.
The sprue 5a, the runner 4a, the gate 3a, the cavity 2a, and the pressed shape forming portion 6a are divided into the movable mold 8 and the fixed mold 9, but the gate 3a, the cavity 2a, the pressed shape are formed. Most of the recesses that become the shape forming portion 6a are formed on the movable mold 8 side, and the fixed mold 9 side is substantially flat and has a shape that closes the recess.

  The sprue 5a is formed in a long shape along the releasing direction of the movable mold 8, and the runner 4a is radially plural from the tip of the sprue 5a in a direction perpendicular to the axial direction of the sprue 5a, four here. The runner 4a is extended and formed. The base end portion of the runner 4a communicates with the tip end portion of the sprue 5a. Further, the runner 4a is provided with a shape for forming the above-described protrusion 41.

The gate 3a is connected to the tip of the runner 4a, and the runner 4a and the gate 3a communicate with each other. A cavity 2a is continuously formed on the distal end side of the gate 3a, and a pressed shape forming portion 6a is provided on the opposite side of the cavity 2a from the gate 3a. When a plurality of pressed parts 6 are formed, a plurality of pressed shape forming parts 6a are formed. In this case, a plurality of pressed shape forming parts 6a are formed at intervals.
In the fixed mold 9, a portion that becomes the formation surface of the cavity 2 a is a nest 54.
Further, in the fixed mold 9, the portions on the fixed mold 9 side of the base end portions of the cavity 2 a and the runner 4 a are nested 55.

When the fixed mold 9 and the movable mold 8 are opened, the molded product 10 remains on the movable mold 8 side and is held.
In the movable mold 8, a portion that becomes the formation surface of the cavity 2 a is a nest 50.
Further, the movable die 8 is pushed to push the circular portion 62 of the pressed portion 6 formed by the pressed shape forming portion 6 a of the molded product 10 along the moving direction of the mold opening of the movable die 8. An eject pin 71 as a member is provided.

Further, the movable mold 8 has an eject pin 72 as a runner pushing member that pushes the protrusion 41 of the runner portion 4 formed by the runner 4 a of the molded product 10 along the moving direction of the mold opening of the movable mold 8. Is provided.
Further, the movable mold 8 is provided with an eject pin 73 as a sprue pushing member that pushes the sprue portion 5 formed by the sprue 5a of the molded product 10 along the moving direction of the mold opening of the movable mold 8. .

The insert 50, the eject pin 71, the eject pin 72, and the eject pin 73 are movable in the same direction as each other, that is, in a direction parallel to the moving direction when the movable mold 8 is opened. (A direction approaching the fixed mold 9) and a retreat (a direction away from the fixed mold 9) are possible. That is, it is driven back and forth.
In addition, the eject pins 71, 72, 73 can move forward a longer distance than the insert 50.

In such an injection molding apparatus, as shown in FIG. 10, the molten thermoplastic resin is injected from the sprue 5a side with the fixed mold 9 and the movable mold 8 attached to each other, and the sprue 5a, the runner 4a, The gate 3a, the cavity 2a, and the pressed shape forming portion 6a are filled with a thermoplastic resin. Then, when the filled resin is cooled and solidified to some extent, the movable mold 8 is moved away from the fixed mold 9 to open the mold as shown in FIG.
As a result, the molded product 10 made of the filled thermoplastic resin remains on the movable mold 8 side and is released from the fixed mold 9.

Next, as shown in FIG. 12, in the movable mold 8, the insert 50 and the eject pins 71, 72, 73 are advanced toward the fixed mold 9 side substantially simultaneously and at the same speed.
Thereby, the sprue part 5 is pushed out from the sprue 5a on the movable mold 8 side, the runner part 4 is pushed out from the runner 4a, the pushed part 6 is pushed out from the pushed shape forming part 6a, and the product part 2 is moved to the movable mold. Extrude from 8. At this time, the gate portion 3 is also pushed out from the gate 3a.

  Therefore, the sprue part 5, the runner part 4, the gate part 3, and the pressed part 6 of the molded product 10 are in a released state. However, the tip surfaces of the eject pins 71, 72, 73 are in contact with the circular portion 62 of the pressed portion 6, the protrusion 41 of the runner portion 4, and the rear end of the sprue portion 5. However, these contact surfaces are substantially flat surfaces orthogonal to the release direction, and the circular portion 62 of the pressed portion 6 and the protruding portion of the runner portion 4 with respect to the tip surfaces of the eject pins 71, 72, 73. 41 and the rear end of the sprue portion 5 can be easily removed.

  Further, since the product part 2 has a cavity 2a on the movable mold 8 side for molding the product part 2 formed on the distal end surface of the insert 50, the product part 2 is in this state the cavity 2a on the movable mold 8 side. It is not in a released state. Further, the cavity 2a on the movable mold 8 side is in a state of being recessed in a dome shape, and the product part of the molded product 10 is in a state of protruding in a dome shape having the same shape as that of the cavity 2a. Is in a state where it cannot be released.

In particular, in this example, in the resin lens 1 of the product part 2 as described above, the angle of the tangential direction orthogonal to the circumferential direction in the outermost peripheral part of the optical function part 11 is relative to the plane orthogonal to the optical axis. Since it is about 75 degrees, the resistance when releasing the product part 2 from the cavity 2a is large.
Further, the product part 2 is provided with an annular recess 15 at the boundary between the optical function part 11 and the flange part 12, and a part of the formation surface of the cavity 2 a is formed in the recess 15 of the product part 2. The annular ridge (convex part) is in a state of entering. That is, the nest 50 of the movable mold 8 is provided with a convex portion that faces the molded product 10 along the mold release direction. Here, the thermoplastic resin cooled from the molten state contracts in the mold.

At this time, the annular protrusion on the surface on which the cavity 2a is formed does not shrink as much as the molded product 10, whereas the annular recess 15 in the state where the annular protrusion is inserted shrinks. The diameter is reduced. As a result, the annular ridge is tightened by the annular recess 15 having a reduced diameter.
Thereby, the resistance at the time of releasing the product part 2 from the cavity 2a increases.

Similarly, in the annular zone 17, a concave structure is formed as described above, and the nest 50 of the movable mold 8 is directed to the molded product 10 along the mold release direction so as to enter the concave structure. An annular ridge (projection) is provided. Then, due to the shrinkage of the molded product 10 to be cooled in the same manner as in the case of the concave portion 15, the annular protrusion (convex portion) on the formation surface of the cavity 2a is tightened, and the product portion 2 is released from the cavity 2a. The resistance when doing so increases.
From these things, when extruding the molded product 10, there is a great resistance to releasing the product part 2 from the formation surface at the tip of the insert 50.
On the other hand, in this example, as described above, the entire molded article 10 is pushed out by the insert 50 and the eject pins 71, 72, 73 as described above, but in this state, the product is still on the forming surface at the tip of the insert 50. The surface of the part 2 on the side of the movable mold 8 is in contact.

At this stage, as shown in FIG. 13, the insert 50 is stopped, and only the eject pins 71, 72, 73 are further advanced. At this time, the eject pins 71, 72, 73 are simultaneously advanced at the same speed. As a result, the product part 2 is released from the formation surface of the cavity 2 a on the distal end surface of the insert 50.
When releasing the product part 2 from the insert 50, the moving speed of the insert 50 and the moving speed of the ejector pins 71, 72, 73 are changed so as to be different from each other, and the above-mentioned molded product is used. The tip of the insert 50 is located behind the tip of the ejector pins 71, 72, and 73 with respect to the traveling direction (push-out direction) of the insert 50 and the ejector pins 71, 72, and 73 when the 10 is pushed out. What should I do?

Therefore, for example, the insert 50 may be pulled back with the eject pins 71, 72, 73 stopped.
When releasing the product part 2 from the insert 50 as described above, the runner part 4 and the sprue part 5 are not only pushed by the eject pins 72 and 73 but also connected to the product part 2 at a position away from the runner part 4. Since the pressed portion 6 is pushed out by the eject pin 71, stress concentrates on the thin and fragile gate portion 3 between the product portion 2 and the runner portion 4 as when only the runner portion 4 side is pushed. Can be prevented.

As a result, stress concentrates on the gate portion 3 and the gate portion 3 bends, as in the case where only the runner 4a side is pushed out against the resistance force acting between the product portion 2 and the formation surface of the cavity 2a. Can be prevented.
As a result, the shape of the molded product 10 does not change every time it is molded, so that the molded product 10 has a stable shape. Therefore, in the subsequent process of forming the resin lens 1 by cutting the product portion 2 from the molded product 10, a stable shape is obtained. Since the molded article 10 is supplied, it is possible to stably perform the processing and to reduce the cost.

Further, when distortion occurs in the gate part 3 due to the concentration of stress such that the gate part 3 bends, or when distortion occurs due to actual bending of the gate part 3, the distortion occurs in the product part 2, particularly in the product part. It is possible to prevent the optical characteristics of the resin lens from deteriorating by reaching the optical function part 11 of the resin lens 1 which is 2.
Further, when the product part 2 is released from the forming surface of the insert 50, the part of the molded product 10 excluding the product part 2 is already released, and the product part 2 is formed of the insert 50. When releasing from the surface, the release state of other parts of the molded product 10 is not affected. That is, it is not hindered that the product part 2 is pulled up simultaneously by the pressed part 6 and the gate part 3 due to, for example, the release of the pressed part 6 being delayed from the gate part 3 or vice versa. As a result, it is possible to prevent stress from concentrating on the boundary portion of the pressed portion 6 of the product portion 2 or concentrating stress on the boundary portion of the product portion 2 with the gate portion 3.

  Therefore, as described above, the tangent angle is approximately 75 degrees, and the resin lens 1 that is difficult to be released by the recess 15 and the annular zone 17 can be easily manufactured without deteriorating the optical characteristics. It becomes possible to do. In other words, the resin lens 1 has the recessed portion 15 and the annular zone 17 and has the pressed portion 6 at the time of molding as described above even when the angle of the outer peripheral portion is large, and the product portion 2 is gated. By having a shape that allows the pressed portion 6 to be extruded at the same time as the runner portion 4 that is connected via the portion 3 is extruded, it can be manufactured at low cost and has sufficient optical characteristics. Can be provided.

It is a top view which shows the molded article containing the resin lens which concerns on embodiment of this invention. It is sectional drawing which shows the said molded article. It is a principal part expanded bottom view which shows the said molded article. It is a principal part expanded side view which shows the said molded article. It is sectional drawing which shows the said resin lens. It is a top view which shows the said resin lens. It is a top view which shows the modification of the said resin lens. It is sectional drawing which shows another modification of the said resin lens. It is a top view which shows the said modification of the said resin lens. It is principal part sectional drawing which shows the injection molding apparatus of embodiment of this invention. It is principal part sectional drawing which shows the said injection molding apparatus. It is principal part sectional drawing which shows the said injection molding apparatus. It is principal part sectional drawing which shows the said injection molding apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin lens 2 Product part 2a Cavity 3 Gate part 3a Gate 4 Runner part 4a Runner 5 Sprue part 5a Spru 6 Pressed part 6a Pressed shape formation part 15 Recess 16 Ring zone 17 Ring zone 50 Nesting (release means)
71 Eject Pin (Pressed Part Extruding Member)
72 Eject pin (runner extrusion member)

Claims (4)

A mold provided with a first mold that opens and a second mold, and a first mold that holds the molded product when the mold is opened, and the molded product is released from the first mold. An injection molding apparatus for molding a resin lens having a release means,
The mold includes a cavity for molding a product part to be a resin lens, a runner connected to the cavity and supplying resin to the cavity, and connected to the cavity and supplied with resin through the cavity. One pressed shape forming part,
The mold release means has a forming surface to be a cavity of a first mold, and a insert for extruding a product part molded by the cavity of the molded product from the first mold,
A runner extruding member for extruding a runner portion formed by the runner of the molded product from the first mold;
Including at least one pressed portion pushing member that pushes out the pressed portion formed by the pressed shape forming portion of the molded product from the first mold,
The mold release means is configured to advance the insert, the runner extruding member, and the pressed member extruding member at substantially the same moving speed and extrude the molded product from the first mold, and then release the mold.
By changing the moving speed of the nest and the moving speeds of the runner push-out member and the pressed portion extruding material so as to be relatively different while the nest is moved without being stopped , the runner An injection molding apparatus characterized in that the product portion of the molded product is pushed out of the insert and released from the mold by moving the insert relative to the push member and the pressed member push member. The resin lens has a convex shape having a light collecting function,
In the portion corresponding to the outermost peripheral portion of the optical functional surface having the optical function of the resin lens, the nest forming surface is molded with respect to a plane perpendicular to the optical axis direction of the resin lens. 2. The injection molding apparatus according to claim 1, wherein a tangent line orthogonal to the circumferential direction of the resin lens is 65 degrees or more and 85 degrees or less.   The injection molding apparatus according to claim 1 or 2, wherein a convex portion directed to the molded product along the mold release direction is provided on a surface on which the insert is formed. Molded product mold release for releasing a molded product from a first mold that holds the molded product when the mold is opened when a resin lens is injection molded by a mold having a first mold and a second mold that are opened. A method,
The injection mold includes a cavity that molds a product portion that becomes a resin lens, a runner that is connected to the cavity and supplies resin to the cavity, and is connected to the cavity and supplied with resin through the cavity. And at least one pressed shape forming part.
In addition, the first mold has a forming surface to be a cavity of the first mold, an insert for extruding a product portion formed by the cavity of the molded product from the first mold, and the molded product At least one of the runner pushing member that pushes out the runner portion formed by the runner from the first mold and the pressed portion formed by the pressed shape forming portion of the molded product from the first die. Two pressed parts pushing member,
During mold opening operation or after mold opening, the molded product is pushed out from the first mold by the insert, the runner pushing member, the pressed portion extrusion material, and the molded product is released from the mold,
After the nest, the runner push member, and the pressed portion push member are advanced at the same moving speed at the same time to extrude the molded product from the first mold and release the mold,
By changing the moving speed of the nest and the moving speeds of the runner push-out member and the pressed portion extruding material so as to be relatively different while the nest is moved without being stopped , the runner Molded product mold release characterized in that the product part of the molded product is pushed out of the insert and released by making the nesting relatively retract with respect to the extruded member and the pressed portion extruded member. Method.

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