JP2008207478A - Mold for molding for lenses, and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To conduct working of a flange molding unit and working of a mark molding unit in the same process by deteriorating no surface accuracy of a reference surface. <P>SOLUTION: A bump structure unit 25 projected from a reference surface molding surface 23a is formed in the flange molding unit 23 of a body mold 13 for molding the flange part, etc. of a plastic lens, and a mark molding unit 27 for molding a mark for distinguishing the mold is formed on the upper surface of this bump structure unit 25. Working of the mark molding unit 27 is carried out during the same cutting process as that of the flange molding unit 23, working of carving of only the mark part, such as characters, etc. may be carried out, and, accordingly, it can be completed in a shorter time as compared with a prior art. Since the plastic lens molded in this mold for molding is molded with the mark at the position withdrawn position from the reference surface, it does not affect the surface accuracy of the reference surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mold for molding a lens and a manufacturing method thereof, and more particularly to a lens molding mold having a mark molding portion for molding a mold identification mark on a flange portion of a lens and a manufacturing method thereof.

  As shown in FIG. 6, the conventional plastic lens 2 includes an optical function surface 3 provided at the center and a flange portion 4 provided on the outer periphery of the optical function surface 3. The flange portion 4 is formed so as to be orthogonal to the lens optical axis L 1, and provided with a reference surface 5 that serves as a reference for attachment to a lens barrel or the like and an outer diameter surface 6 that serves as an outer diameter reference for the plastic lens 2. It has been. The reference surface 5 is provided with a concave mark 7 for identifying a molding die used for molding the plastic lens 2.

  In conventional plastic lens molds, a mark is formed without impairing the function as a reference surface. Therefore, a convex mark forming part is formed on the reference surface forming surface, and a concave mark is formed on the reference surface. I am doing so. The convex mark forming portion is formed by finely removing the entire periphery of the convex shape by performing electric discharge machining using an electrode obtained by compressing metal powder.

As a conventional method for forming a mark on a molded workpiece, a mark-shaped protrusion is formed on an eject pin that ejects the molded workpiece from a molding die, and the protrusion is pressed simultaneously with the ejection to form a mark. A method is known (see, for example, Patent Document 1). In addition, a method is known in which an electric discharge machining is performed on a molding die using a die-sculpting electrode having a mark shape to form a mark forming portion including a mark-shaped concave portion (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 06-143360 JP 09-039042 A

  In the method of depositing and forming a convex mark forming part by electric discharge machining, there is a problem that the surface around the discharge mark forming part becomes rough because the metal melted from the electrode adheres to the surroundings. Further, in manufacturing a molding die, there is a problem that manufacturing time and cost increase because processing of the flange forming portion for forming the flange portion and electric discharge processing of the mark forming portion are performed in separate steps.

  Further, in the method of forming a mark with an eject pin, the size of the mark that can be formed is limited. Further, since it is necessary to provide a hole through which the eject pin is inserted into the molding die and a mechanism for moving the eject pin, the cost and manufacturing man-hour of the molding die increase. Further, the method of forming a concave mark forming portion by electric discharge machining cannot be adopted because the mark protrudes from the reference surface.

  In order to solve the above problems, the present invention provides a lens molding die that can perform the processing of the flange molding portion and the processing of the mark molding portion in the same process without deteriorating the surface accuracy of the reference surface. And a method for manufacturing the same.

  In order to solve the above-described problems, a lens mold according to the present invention has an optical function surface and a flange portion provided on the outer periphery of the optical function surface, and the flange portion includes a reference surface orthogonal to the lens optical axis. And a mold for molding a lens provided with an outer diameter surface that defines an outer diameter of the lens, each having an optical function surface molding portion for molding an optical function surface and a flange molding portion for molding a flange portion, At least one of the fixed mold and movable mold in which a cavity corresponding to the lens is formed when fastened and at least one flange molding section of the fixed mold and movable mold is provided, and protrudes from the reference surface molding surface to be the upper part Are formed of a stepped portion having a marking surface and a concave mark forming portion provided on the marking surface for forming a mark for mold identification.

  Further, the height of the stepped portion is made larger than the depth of the mark forming portion.

  Further, when the lens is provided on the outer periphery of the optical function surface and has a connecting portion that connects the flange portion, a fixed portion and a movable die are provided with a connecting portion forming portion that forms the connecting portion, and this connecting portion molding is performed. A stepped portion is connected to the outer periphery of the portion.

  Moreover, the manufacturing method of the molding die for lenses of this invention forms a flange molding part, a level | step difference part, and a mark molding part by the same cutting process.

  According to the lens molding die of the present invention, since the mark molding portion is provided at the stepped portion protruding from the reference surface, the molded lens is formed with a mark at a position retracted from the reference surface. Thereby, the mark does not affect the surface accuracy of the reference surface.

  Further, since the mark is formed at the position where the mark is retracted from the reference surface by the stepped portion, the mark forming portion can be formed in a concave shape. Since the height of the stepped portion is made larger than the depth of the mark forming portion, the mark does not protrude from the reference surface in the lens after molding.

  In addition, since the stepped portion is connected to the connecting portion, a part of the connecting portion can be used as the stepped portion, and an area larger than the engraved surface obtained only by the stepped portion can be obtained. Easy marks can be formed.

  Further, according to the method for manufacturing a lens molding die of the present invention, since the mark molding part is concave, it can be processed by engraving only the mark molding part in the same cutting process as the flange molding part and the like. It can be processed in a very short time as compared with the conventional process of cutting the entire periphery while leaving the mark forming part.

  A molding die 10 shown in FIG. 1 is a molding die for injection molding a plastic lens, and includes a fixed die 11 and a movable die 12. The movable mold 12 is movable between a mold split position that is separated from the fixed mold 11 and a mold clamping position that is joined to the fixed mold 11. When the movable mold 12 is in the mold clamping position, a cavity 22 corresponding to a plastic lens is formed between the movable mold 12 and the fixed mold 11, and the cavity 22 is filled with molten plastic.

  The fixed mold 11 and the movable mold 12 are inserted into body molds 13 and 14 for molding a flange portion of a plastic lens and the like, and mounting holes 15 and 16 formed in the body molds 13 and 14 to mold an optical functional surface. It comprises core molds 17 and 18 and molds 19 and 20 for holding main body molds 13 and 14 and core molds 17 and 18, respectively.

  As shown in FIGS. 2 and 3, the body die 13 is formed on the outer periphery of the core die 17 to form a flange forming portion 23 for forming the flange portion, and a connecting portion for connecting the optical functional surface and the flange portion. The connecting portion forming portion 24, the step portion 25 formed to be connected to the outer periphery of the connecting portion forming portion 24, the marking surface 26 provided on the upper surface of the step portion 25, and the concave shape provided on the marking surface 26. And a mark forming portion 27. Note that the height H of the step portion 25 from the reference surface molding surface 23 a is larger than the depth D of the mark molding portion 27.

  By forming the step portion 25 so as to be connected to the connecting portion forming portion 24, a part of the upper surface of the connecting portion forming portion 24 can be used as the marking surface 26. Thereby, since the marking surface 26 having a larger area than the size of the stepped portion 25 can be obtained, the mark forming portion 27 can be enlarged or the number of characters can be increased.

  Since the mark forming portion 27 has a concave shape, it can be processed in the same cutting process as the flange forming portion 23 and the like. As shown in FIG. 4, the main body mold 13 is set on a milling machine, the flange forming portion 23 and the stepped portion 25 are processed using a thick end mill 30, and the mark forming portion 27 is processed by replacing the thin end mill 31. Thereby, the manufacturing cost and manufacturing man-hour of a shaping die can be reduced.

  As shown in FIG. 5, the plastic lens 40 molded by the molding die 10 includes an optical function surface 41 provided at the center, a flange portion 42 provided on the outer periphery of the optical function surface 41, an optical function surface 41, and the like. A connecting portion 43 provided between the flange portions 42 and connecting the two is provided.

  The flange portion 42 is formed so as to be orthogonal to the lens optical axis L, and is provided with a reference surface 44 that serves as a reference for attachment to the lens barrel and the like and an outer diameter surface 45 that serves as a reference for the outer diameter of the plastic lens 40. It has been. The reference surface 44 is provided with a notched portion 46 formed by the stepped portion 25 and notched at a depth reaching the connecting portion 43, and a convex mark 47 is provided in the notched portion 46. The marking part 48 provided with is formed. The mark 47 is used for identifying the molding die 10 used for molding the plastic lens 40.

  Since the plastic lens 40 is provided in the marking portion 48 in which the mark 47 is retracted from the reference surface 44, the surface of the reference surface 44 is compared with the conventional plastic lens 2 (see FIG. 6) in which the mark is provided on the reference surface 44. The accuracy is improved, and the positional deviation or the like when the lens barrel is assembled can be reduced. Further, since the height H of the stepped portion 25 of the main body mold 13 is larger than the depth D of the mark forming portion 27, the mark 47 formed in a convex shape does not protrude from the reference surface 44.

  In the above-described embodiment, the molding die in which the optical function surface is molded with the core mold is described as an example. However, the present invention can also be applied to a molding die that does not use the core mold. Further, although the step portion is provided to be connected to the connecting portion, it may be provided apart from the connecting portion, or in the case of a molding die having no connecting portion, it is connected to the side surface of the optical function surface forming portion. A step portion may be provided on the surface, and is preferably provided at a position where the surface accuracy of the reference surface and the outer diameter surface is not affected. Furthermore, although an injection mold has been described as an example, the present invention can also be applied to a press mold. Further, the plastic lens has been described as an example, but it can also be used for press molding of a glass lens.

It is sectional drawing which shows the schematic structure of the shaping die of this invention. It is an external appearance perspective view which shows the structure of a fixed type | mold. It is sectional drawing which shows the structure of a fixed type | mold. It is explanatory drawing which shows the cutting process of a fixed-type main body type | mold. It is an external appearance perspective view of the plastic lens shape | molded by the shaping die of this invention. It is an external appearance perspective view of the plastic lens shape | molded by the conventional shaping die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Molding die 11 Fixed type 12 Movable type | mold 13,14 Main body type | mold 15,16 Mounting hole 17,18 Core type | mold 22 Cavity 23 Flange molding part 23a Reference surface molding surface 24 Connecting part molding part 25 Step part 26 Marking surface 27 Mark molding Part 30 End mill 40 Plastic lens 41 Optical functional surface 42 Flange part 43 Connection part 44 Reference surface 45 Outer diameter surface 46 Notch part 47 Mark 48 Marking part

Claims (4)

A lens having an optical function surface and a flange portion provided on an outer periphery of the optical function surface, and a reference surface orthogonal to a lens optical axis and an outer diameter surface defining a lens outer diameter provided on the flange portion. In the mold for molding
A fixed mold and a movable mold each having an optical function surface molding portion for molding the optical function surface and a flange molding portion for molding the flange portion, and forming a cavity corresponding to the lens when the mold is clamped When,
A step portion provided on at least one of the flange molding portions of either the fixed die or the movable die, protruding from a reference surface molding surface for molding the reference surface, and having a marking surface on the top;
A lens molding die, comprising a concave mark molding portion provided on the marking surface and molding a mold identification mark.   The lens molding die according to claim 1, wherein a height of the step portion is larger than a depth of the mark molding portion.   When the lens has a connecting portion that is provided on the outer periphery of the optical function surface and connects the flange portion, the fixed mold and the movable mold are provided with a connecting portion forming portion that forms the connecting portion, 3. The molding die for a lens according to claim 1, wherein the step portion is provided so as to be connected to the outer periphery of the connecting portion molding portion. In the manufacturing method of the molding die for lenses according to any one of claims 1 to 3,
The method for manufacturing a molding die for a lens, wherein the flange forming portion, the stepped portion and the mark forming portion are formed by the same cutting process.

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