JP2008284704A - Mold and method of manufacturing optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold which can form a high-precision article, and has a core facilitating shape generation of a molding surface and handling. <P>SOLUTION: In the molding mold composed of a movable side mold part 1 and a fixed side mold part 2, a movable side core 7 and a fixed side core 8 composing a cavity C for molding a lens 13 by mutually opposing them, are made to be a structure of a plurality of layers composed of a first layer 7a, a second layer 7b, a third layer 7c, and the first layer 8a, the second layer 8b, the third layer 8c. The first layer 7a and the second layer 8a in contact with the lens 13 are constituted by a high rigid stainless steel, and the second layer 7b and the second layer 8b of the rear are constituted by a raw material such as glass or the like which has smaller coefficient of thermal conductivity than that of the first layer 7a and the first layer 8a. Breakage prevention by improving the strength of a lens molded surface 7a-1 and a lens molded surface 8a-1 formed on the first layer 7a and the first layer 8a and the accuracy improvement by gradually cooling of the thin walled part of the lens 13 are compatible with each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mold and a method for manufacturing an optical element, and more particularly to a mold molding technique for injection molding a molding object such as a high-precision resin lens.

  For example, a technique for efficiently mass-producing optical elements such as high-precision lenses by injection molding technology has been widespread. In this case, for example, it is important from the viewpoint of performing high-precision molding to make the cooling rate uniform during curing of the resin without being affected by the thickness of the lens.

  For this reason, for example, in the technique disclosed in Patent Document 1, a technique is disclosed in which a nest having a molding surface that is detachably attached to a mold and forms a cavity is formed of a material having low thermal conductivity. .

  According to the technique of this Patent Document 1, since the nesting is formed of a material having low thermal conductivity, the cooling and solidification of the thin portion of the plastic lens is delayed, and the difference in the solidification time from the thick portion can be reduced. Therefore, it is possible to obtain a highly accurate resin lens with little difference in deformation amount between lens parts.

  In the above-mentioned Patent Document 1, machinable ceramics and ceramics are applied as the material constituting the nesting, but these materials having low thermal conductivity are generally brittle materials. For this reason, the mechanical properties of the material are extremely fragile, and the molding surface that comes into contact with the lens during molding can be easily damaged with a slight impact. There has been a technical problem that the edge portion is lost during handling due to, for example, and there is a concern that it cannot be used as a mold.

Such breakage of the insert causes a decrease in the operating rate of the molding process due to the replacement operation of the insert, an increase in the manufacturing cost of the insert including the manufacture of the replacement insert, and a decrease in productivity of the molding process of the optical element. Will contribute.
Japanese Patent Laid-Open No. 5-200789

An object of the present invention is to provide a molding die having a nesting that allows easy creation of the shape of the molding surface and easy handling while obtaining a highly accurate workpiece.
Another object of the present invention is to provide a technique capable of reducing the frequency of replacement and remanufacturing due to breakage of the mold insert and improving the productivity of the optical element molding process.

A first aspect of the present invention is a mold including a nest in which a molding surface for molding a molding is formed,
The insert includes a first layer having the molding surface in contact with the workpiece, and a second layer adjacent to the first layer, and the second layer has a thermal conductivity higher than that of the first layer. A mold formed of a low material is provided.

According to a second aspect of the present invention, a step of forming a cavity by nesting formed by disposing a second layer having a lower thermal conductivity than the first layer on the back side of the first layer constituting the molding surface;
Pressing the plastic material into the cavity to obtain an optical element;
The manufacturing method of the optical element containing is provided.

  That is, in the present invention, as an example, in a mold for injection-molding a molded object such as a resin lens, the nesting constituting the cavity includes a first layer that contacts the resin lens and a second layer adjacent to the first layer. It is composed of a layer or more member. The first layer is formed of, for example, a metal material as a base material, and the second layer is formed of a material having a lower thermal conductivity than the base material constituting the first layer.

  As described above, the second layer is made of a material having a low thermal conductivity, so that, for example, the cooling and solidification of the thin portion of the optical element (molded body) such as a plastic lens is delayed, and the solidification with the thick portion is performed. Since the time difference can be reduced, it is possible to obtain a highly accurate resin lens with little difference in deformation amount between lens parts. In addition, the first layer in contact with the lens uses a metal material as a base material and has high fracture toughness, so that the edge portion of the mold is not easily chipped.

Further, the second layer can be formed of, for example, glass and welded to the first layer.
Thereby, the 2nd layer can be uniformly joined to the whole butt surface by welding to the 1st layer.

Further, the lens molding surface of the first layer can be covered with, for example, P—Ni plating or Ni—Cu—P plating.
Thereby, it is possible to easily obtain a highly accurate forming surface by cutting with a single crystal diamond tool.

  In the mold described above, the portion facing the first layer (the portion surrounding the first layer) of the template on which the insert is mounted is made of a material having a lower thermal conductivity than the material forming the first layer. can do.

  Thereby, by suppressing the thermal diffusion from the outer periphery of the first layer, the cooling delay action of the resin lens is enhanced, and the lens can be molded with higher accuracy.

ADVANTAGE OF THE INVENTION According to this invention, while providing a highly accurate to-be-molded object, the shaping | molding die provided with the nest | insert with which the creation of the shape of a molding surface and easy handling can be provided.
Further, it is possible to provide a technique capable of reducing the frequency of replacement or remanufacturing due to breakage of the mold insert and improving the productivity of the molding process of the optical element.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Embodiment 1]
FIG. 1 is a cross-sectional view of a mold which is an example of a mold used in an injection molding process for carrying out an optical element manufacturing method according to an embodiment of the present invention.

As an overall configuration, an injection molding die used in the embodiment is composed of a movable mold portion 1 and a fixed mold portion 2.
The movable mold part 1 has a structure in which a movable insert 7 inserted in a movable mold 5 is advanced and retracted in the opening and closing direction of the mold by the insert projecting means 10.

  The fixed-side mold part 2 has a fixed-side mold plate 6 fixed to a fixed-side mounting plate 4, and the fixed-side mold plate 6 is opposed to the movable side insert 7 on the fixed-side mold plate 6 side. The fixed-side insert 8 is inserted in the position to be. The fixed side insert 8 is fixed to the fixed side mounting plate 4 with bolts 12.

  The movable side template 5 and the fixed side template 6 are provided with heaters (not shown), and the movable side template 5 and the fixed side template 8 provided on the movable side template 5 and the fixed side template 6 are provided with desired heaters. It is possible to heat to the molding temperature, to cool, and to arbitrarily control the heating rate and the cooling rate.

The movable side mounting plate 3 is provided with a through-hole 3a for inserting a drive shaft that advances and retreats by a servo motor or a hydraulic cylinder (not shown).
A resin injection port 4 a is formed in the fixed side mounting plate 4. The fixed-side template 6 is provided with a pressure feed path 6a penetrating in the thickness direction at a position corresponding to the resin injection port 4a. The pressure feed path 6a communicates with a runner 5a described later. The pressure feed path 6a is provided with a draft that gradually increases in cross-sectional area toward the movable side mold plate 5, and the resin 20 filled in the pressure feed path 6a can be easily removed at the time of mold release. It has become.

Hereinafter, the details of the configuration of the movable mold part 1 will be described.
A receiving plate 11 and a movable side mold plate 5 are fixed to a movable side mounting plate 3 in the movable side mold part 1 via a spacer block 9. The nesting protrusion means 10 between the movable side mounting plate 3 and the receiving plate 11 includes a protruding plate 10a, a protruding plate 10b, and a protruding rod 10d. The protruding plates 10a and 10b are provided so as to be slidable in the mold opening / closing direction (left-right direction in FIG. 1).

  Further, the protruding rod 10 d is disposed through the protruding plate 10 b and the receiving plate 11, a bolt 10 c is inserted therein, and the tip of the bolt 10 c is screwed to the bottom surface of the movable side insert 7. The protruding plate 10b holds an ejector pin 10e penetrating the receiving plate 11 and the movable mold plate 5. The ejector pin 10e protrudes from the movable side mold plate 5 to extrude the molded product and release it.

Next, the configuration of the movable side insert 7 and the fixed side insert 8 in the first embodiment will be described in detail.
The movable side insert 7 according to the first embodiment includes a first layer 7a that comes into contact with the lens 13 that is a molded body, a third layer 7c that forms the bottom surface of the movable side insert 7, and a second layer sandwiched between them. 7b.

In this case, as an example, the first layer 7a and the third layer 7c of the movable side insert 7 are made of stainless steel as a base material.
The lens molding surface 7a-1 of the first layer 7a is provided with a coating layer made of, for example, P-Ni plating. The shape of the lens to be molded is highly accurate by any one of cutting, grinding, and polishing. The shape has been created.

The second layer 7b is made of glass having both end surfaces formed in a planar shape, and is bonded to the first layer 7a and the third layer 7c by glass welding.
The bottom surface portion of the third layer 7c is connected to the nesting protrusion means 10 via the bolt 10c as described above.

  The fixed side insert 8 has the same configuration as that of the movable side insert 7 described above, and the second layer 8b made of glass is sandwiched between the first layer 8a and the third layer 8c formed of stainless steel as a base material. It has become. Further, the bottom surface of the third layer is fixed to the fixed side mounting plate 4 via bolts 12.

  The first layer 8a is provided with a lens molding surface 8a-1 on which a coating layer by P-Ni plating is formed. Similarly to the above-described lens molding surface 7a-1, the lens molding surface 8a-1 is also shaped with high accuracy by any one of cutting, grinding, and polishing processes for the shape of the lens 13 to be molded.

  In the clamped state in which the movable side mold plate 5 and the fixed side mold plate 6 are in close contact with each other, molding is performed by the lens molding surface 7a-1 of the movable side insert 7 and the lens molding surface 8a-1 of the fixed side insert 8 facing each other. A cavity C is formed as a space.

  The cavity C communicates with one end of a runner 5 a engraved on the opposing surfaces of the movable side mold plate 5 and the fixed side mold plate 6. A gate 5b having a reduced diameter is provided at a communicating portion with respect to the cavity C of the runner 5a. The other end of the runner 5a communicates with the above-described pressure feed path 6a.

  In the present embodiment, the shape of the coupling surface of the first layers 7a and 8a of the movable side inserts 7 and 8 and the second layers 7b and 8b made of glass is not limited to a flat surface. 13 curved surfaces (optical surfaces) and approximate shapes may be used. Moreover, the coating layer by Ni-Cu-P plating, for example may be formed in the lens molding surfaces 7a-1 and 8a-1 of the first layers 7a and 8a.

  Next, the operation of the first embodiment will be described. In the injection mold according to the present embodiment configured as described above, first, the movable side mold plate 5 and the fixed side mold plate 6 are heated to a desired molding temperature.

Then, by bringing the movable-side mounting plate 3 closer to the fixed-side mold part 2, the mold-clamping state in which the movable-side mold plate 5 and the movable-side insert 7 come into contact with the fixed-side mold plate 6 and the fixed-side insert 8 respectively. Become.
As a result, the molten resin 20 passes through the resin injection port 4a, the pumping path 6a, the runner 5a, and the gate 5b into the cavity C formed between the lens molding surface 7a-1 and the lens molding surface 8a-1 facing each other. The lens 13 having an optical surface onto which the shapes of the lens molding surface 7a-1 and the lens molding surface 8a-1 are accurately transferred is molded.

  The lens 13 molded in the cavity C is cooled by lowering the temperatures of the movable side mold plate 5 and the fixed side mold plate 6. Then, after the lens 13 is cooled to a predetermined temperature, the movable side mold plate 5 is separated from the fixed side mold plate 6, and the movable side insert 7 and the ejector pin 10e are protruded, so that the lens 13 and the runner 5a connected to the lens 13 are provided. A mold release operation for separating the resin 20 from the cavity C and the movable side mold plate 5 is performed.

  Here, in the present embodiment, the movable side insert 7 and the fixed side insert 8 have a three-layer structure in the longitudinal direction as described above, and the lens forming surface 7a-1 (lens forming surface 8a- 1) is the second layer 7b (first layer) of the glass so as to be sandwiched between the first layer 7a (first layer 8a) and the third layer 7c (third layer 8c) made of stainless steel forming the bottom of the insert. Two layers 8b) are formed.

  The thermal conductivity k1 of the stainless steel forming the first layer 7a (first layer 8a) is 16 to 24 (W / m · K), and the thermal conductivity of the glass constituting the second layer 7b (second layer 8b). Since k2 is 0.5 to 1.5 (W / m · K) which is 1/10 or less, the temperature of the resin 20 filled in the cavity C is unlikely to decrease during the molding process of the lens 13. Become. As a result, the thin portion of the lens 13 is slowly cooled.

  That is, according to the present embodiment, in the molding process of the lens 13 such as a resin lens by the injection molding method, the cooling rate of the thin portion of the lens 13 becomes slow, so that the difference in cooling time from the thick portion is increased. By eliminating this, a highly accurate resin lens can be obtained.

  In the movable side insert 7 and the fixed side insert 8 constituting the cavity C, the lens forming surface 7a-1 of the first layer 7a and the lens forming surface 8a-1 of the first layer 8a are made of stainless steel having high fracture toughness. Since the base material is used, the edge portion is not easily chipped, a highly accurate nesting lens molding surface is obtained, and handling of the movable nesting 7 and the fixed nesting 8 is simplified.

  In other words, the material of the first layer 7a and the first layer 8a that are in contact with the lens 13 of the movable side insert 7 and the fixed side insert 8 is composed of a highly rigid non-brittle material having an arbitrary thermal conductivity k1. The second layer 7b and the second layer 8b that are in contact therewith are made of a material having a thermal conductivity k2 smaller than the above-described thermal conductivity k1, thereby increasing the strength of the lens molding surface 7a-1 and the lens molding surface 8a-1. It is possible to achieve both improvement and improvement of molding accuracy by controlling the cooling rate of the lens 13 in the cavity C.

Furthermore, since the strengths of the lens molding surface 7a-1 and the lens molding surface 8a-1 of the movable side insert 7 and the fixed side insert 8 are improved, the molding process is performed by the damage or replacement work of the movable side insert 7 and the fixed side insert 8. Stop frequency, and the frequency of re-creation due to breakage of the movable side insert 7 and the fixed side insert 8 is reduced, so that the operating rate of the molding process can be improved and the equipment cost can be reduced. As a result, the productivity of the molding process of the lens 13 is improved.
[Embodiment 2]
FIG. 2 is a cross-sectional view showing an injection mold according to another embodiment of the present invention. In addition, about the location similar to Embodiment 1 mentioned above, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the injection mold according to the second embodiment, among the inner peripheral surfaces of the through holes for inserting the movable side insert 7 and the fixed side insert 8 of the movable side template 5 and the fixed side template 6 respectively. The heat insulating member 14 and the heat insulating member having a lower thermal conductivity than the material constituting the first layer in a portion (the portion surrounding the first layer 7a and 8a) facing the first layers 7a and 8a of each nesting. 15 differs from the first embodiment described above. Other configurations are the same as those in the first embodiment.

That is, the cylindrical heat insulating member 15 is arranged at a position surrounding the first layer 8 a on the distal end side of the fixed side insert 8 on the opening end side of the insertion hole of the fixed side insert 8 in the fixed side template 6.
Similarly, on the opening end side of the insertion hole of the movable side insert 7 in the movable side template 5, a cylindrical heat insulating member 14 is disposed at a position surrounding the first layer 7 a on the distal end side of the movable side insert 7. .

The heat insulating member 14 on the movable template 5 side is formed with a gate 14a penetrating in the radial direction at a position corresponding to the runner 5a.
In the case of this Embodiment 2, as this heat insulation member 14 and the heat insulation member 15, the heat conductivity k3 is the heat conduction of materials, such as stainless steel which comprises the above-mentioned 1st layer 7a and 1st layer 8a, for example. The material is selected from materials such as glass, ceramics such as alumina, and other machinable ceramics that are smaller than the rate k1.

  In the second embodiment, the injection molding of the lens 13 such as a resin lens is performed by bringing the movable side mounting plate 3 close to the fixed side mold portion 2 in the same manner as in the first embodiment. The mold is clamped so that the movable side insert 7 comes into contact with the fixed side template 6 and the fixed side insert 8 respectively.

  As a result, the resin injection port 4a, the pressure feed path 6a, the runner 5a, and the gate 14a are passed through the cavity C formed between the first layer 7a of the movable side insert 7 and the first layer 8a of the fixed side insert 8. The molten resin 20 is supplied and the lens 13 is molded.

  In the second embodiment, as in the first embodiment, the cavity C is filled by the effect of heat insulation of the glass forming the second layers 7b and 8b of the movable side insert 7 and the fixed side insert 8, respectively. As a result, the temperature of the formed resin 20 is not easily lowered, and as a result, the thin portion of the lens 13 is slowly cooled.

  In addition, in the case of the second embodiment, since the heat insulating member 14 and the heat insulating member 15 are disposed, the cooling delay effect in which the thin portion of the lens 13 is slowly cooled is further enhanced.

  In the second embodiment, as in the first embodiment, the shape of the molded lens 13 is obtained by the effect of heat insulation of the glass that forms the second layers 7b and 8b of the movable side insert 7 and the fixed side insert 8, respectively. High accuracy can be achieved.

In addition, the heat insulating effect of the heat insulating member 14 and the heat insulating member 15 makes it possible to mold the lens 13 such as a resin lens with higher accuracy.
Similarly to the first embodiment, since the lens molding surface 7a-1 and the lens molding surface 8a-1 are made of stainless steel having high fracture toughness, the edge portion is not easily chipped and the movable side nesting is highly accurate. 7. Lens molding surfaces 7a-1 and 8a-1 of the fixed side insert 8 are obtained, and the handling of the movable side insert 7 and the fixed side insert 8 is simplified.

  As described above, according to each embodiment of the present invention, it is possible to perform injection molding processing of an optical element such as a high-precision resin lens, and since the fracture toughness of the lens forming surface of the nesting is high, the edge portion is It is hard to chip, and a highly precise nesting lens molding surface is obtained, and handling of the nesting is simplified.

Further, the frequency of replacement or remanufacturing due to breakage of the mold insert can be reduced, and the productivity of the optical element molding process can be improved.
Needless to say, the present invention is not limited to the configuration exemplified in the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, the optical element that is the object to be molded is not limited to the lens 13 and may be, for example, a prism or any other optical element.

It is sectional drawing of the metal mold | die which is an example of the shaping | molding die used by the injection molding process which implements the manufacturing method of the optical element which is one embodiment of this invention. It is sectional drawing which shows the injection mold of other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movable side mold part 2 Fixed side mold part 3 Movable side mounting plate 3a Through hole 4 Fixed side mounting plate 4a Resin injection port 5 Movable side mold plate 5a Runner 5b Gate 6 Fixed side mold plate 6a Pressure feed path 7 Movable side nesting 7a First layer 7a-1 Lens molding surface 7b Second layer 7c Third layer 8 Fixed side insert 8a First layer 8a-1 Lens molding surface 8b Second layer 8c Third layer 9 Spacer block 10 Nesting projection means 10a Projection plate 10b Projection plate 10c Bolt 10d Projection rod 10e Ejector pin 11 Receiving plate 12 Bolt 13 Lens 14 Thermal insulation member 14a Gate 15 Thermal insulation member 20 Resin C Cavity

Claims (9)

A mold including a nest in which a molding surface for molding a molding is formed,
The insert includes a first layer having the molding surface in contact with the workpiece, and a second layer adjacent to the first layer, and the second layer has a thermal conductivity higher than that of the first layer. A mold characterized in that it is made of a low material. The mold according to claim 1, wherein
The mold according to claim 1, wherein the first layer of the insert is made of a metal material, and the second layer is formed of glass and welded to the first layer. The mold according to claim 1, wherein
The molding die, wherein the molding surface of the first layer of the nesting is coated with P-Ni plating or Ni-Cu-P plating. The mold according to claim 1, wherein
A molding die characterized in that a portion surrounding the cavity formed by the molding surface of the first layer of the nesting is made of a material having a lower thermal conductivity than the material forming the first layer. The mold according to claim 1, wherein
The molding die is an optical element made of a resin. Forming a cavity by nesting formed by arranging a second layer having a lower thermal conductivity than the first layer on the back side of the first layer constituting the molding surface;
Pressing the plastic material into the cavity to obtain an optical element;
The manufacturing method of the optical element characterized by the above-mentioned. In the manufacturing method of the optical element according to claim 6,
The method of manufacturing an optical element, wherein the first layer of the insert is made of a metal material, the second layer is formed of glass, and is welded to the first layer. In the manufacturing method of the optical element according to claim 6,
The method of manufacturing an optical element, wherein the molding surface of the first layer of the insert is coated with P-Ni plating or Ni-Cu-P plating. In the manufacturing method of the optical element according to claim 6,
A method of manufacturing an optical element, wherein a member having a lower thermal conductivity than the first layer is disposed around the cavity constituted by the first layer.

Images