JP2008120097A - Injection mold for plastic optical lens and method for producing plastic optical lens - Google Patents

Abstract

An injection mold having a simple structure and high molding accuracy is provided.
A moving side forming sesame 2 having a moving side forming surface 2a, a moving side outer sesame 1 that holds the moving side forming sesame 2 from the outside, and a moving side ball retainer 8 that holds a ball 9 in a ball holding cylinder 10. A fixed-side molded sesame 4 having a fixed-side molded surface 4 a, a fixed-side outer sesame 3 that holds the fixed-side molded sesame 4 from the outside, and a fixed-side ball retainer 8 that holds a large number of balls 9 in a ball holding cylinder 10. With the ball 9 interposed, the movable side molded sesame 2 and the movable side outer sesame 1 are aligned, and the fixed side molded sesame 4 and the fixed side outer sesame 3 are aligned, and the movable side outer sesame 1 is tapered. A concave portion 5 is provided, and a tapered fitting convex portion 6 is provided on the fixed-side outer sesame 3.
[Selection] Figure 1

Description

  The present invention relates to an injection mold for a plastic optical lens and a method for manufacturing a plastic optical lens.

  FIG. 4 is a sectional view of this kind of conventionally proposed injection molding mold. The injection mold 100 includes a fixed mold 101 and a movable mold 102, which are joined to each other at a joining surface 103 so as to be separable.

  The fixed side mold 101 includes a fixed side plate 104 and a mounting plate 105 to which the fixed side plate 104 is attached. A fixed side lens insert 107 having a lens molding surface is fitted to the fixed side plate 104 via a fixed side sleeve 106 and fixed to the fixed side plate mounting plate 105 with a bolt 108. Further, a taper bush 109 is fixed to the fixed plate attaching plate 105 at a position away from the fixed sleeve 106. A gate 113 that communicates with the spool 110, the runner 111, and the cavity 112 is provided at the center of the stationary plate 104.

  The moving side mold 102 includes a moving side plate 114 and a mounting plate 115 to which it is attached. A moving side lens insert 117 having a lens forming surface is fitted to the moving side plate 114 via a moving side sleeve 116. A spacer block 119 is interposed between the receiving plate 118 and the mounting plate 115 of the moving side plate 114, and protruding plates 120 and 121 are installed inside the spacer block 119. The rear end 122a of the protruding rod 122 is held by protruding plates 120 and 121, and the front end 122b of the protruding rod 122 is connected to the moving side lens insert 117 by screws.

  Further, the ejection plates 120 and 121 hold the rear end 123 a of the ejector pin 123, and the front end 123 b of the ejector pin 123 extends to the vicinity of the runner 111.

  The moving side plate 114 is provided with a taper guide 124, and this is fitted to the taper bush 109 to suppress the misalignment between the fixed side lens insert 107 and the moving side lens insert 117.

As for the injection mold, for example, there are proposals as described in Patent Documents 1 to 4 below.
JP-A-60-129229 (FIGS. 3 and 4) Japanese Patent Laid-Open No. 7-329133 (FIGS. 1 and 2) JP-A-8-118432 (FIG. 1) JP-A-9-267362 (FIG. 1)

  However, in this injection mold 100, the taper bush 109 and the taper guide 124 for suppressing the misalignment of the lens inserts 107 and 117 are located away from the lens inserts 107 and 117. , 117, a plurality of members are interposed, and the centering is performed indirectly.

  Further, when the fixed side lens insert 107 is attached to the fixed side plate 104, there is a slight clearance between the fixed side plate 104 and the fixed side sleeve 106 and between the fixed side sleeve 106 and the fixed side lens insert 107. In addition, since the fixed side lens insert 107 is fixed to the mounting plate 105 with the bolt 108, the fixed side lens insert 107 is biased.

  The same is true for the moving lens insert 117, and there is a slight clear land between the moving plate 114 and the moving sleeve 116 and between the moving sleeve 116 and the moving lens insert 117. In addition, since the moving lens insert 117 protrudes and is screwed by the tip 122b of the rod 122, the moving lens insert 117 is biased.

  For this reason, a misalignment occurs between the fixed side lens insert 107 and the moving side lens insert 117, and in the case of an optical lens, the misalignment appears as a shift of the optical axis, resulting in a reduction in molding quality. There is.

  An object of the present invention is to eliminate such problems of the prior art, and to provide an injection mold for a plastic optical lens having a simple structure and high molding accuracy, and a method for manufacturing the plastic optical lens.

  In order to achieve the above object, the first means of the present invention includes a stationary mold and a movable mold, at least the movable mold having a movable molding surface, A moving side holding member such as a moving side outer sesame, which will be described later, for holding the moving side molded sesame from the outside, and a moving side ball retainer that holds the ball rotatably on the peripheral wall of the ball holding cylinder, The moving-side ball retainer is inserted between the moving-side molded sesame and the moving-side holding member, and the moving-side formed sesame and the moving-side holding member are aligned by the ball, and the moving-side holding member or the fixed side Either one of the molds is provided with a fitting recess having a tapered surface on the peripheral surface, and either the stationary mold or the moving side holding member has a tapered surface on the peripheral surface and is fitted with the fitting recess. Features a mating projection that fits together It is intended to.

  According to a second means of the present invention, in the first means, the fixed-side mold holds a fixed-side molded sesame having a fixed-side molding surface and the fixed-side molded sesame from the outside, for example, a fixed side described later. A fixed-side holding member such as an outer sesame, and a fixed-side ball retainer that rotatably holds a ball on the peripheral wall of the ball holding cylinder with a space therebetween. The fixed-side ball retainer is formed of a fixed-side molded sesame and a fixed-side holding member. The fixed side molding sesame and the fixed side holding member are centered by interposing the ball between them.

  The third means of the present invention uses the injection mold of the first means or the second means, joins the fixed side mold and the moving side mold, and is in the cavity formed between them. A plastic optical lens is manufactured by injecting and filling a molten resin.

  According to the present invention, at least the centering between the movable side molding sesame and the movable side holding member is reliable, and the gap between the molding sesame and the holding member can be ensured uniformly, resulting in a smooth and stable movement. In addition, the fixed-side mold and the moving-side mold are accurately centered by taper fitting between the fixed-side mold and the moving-side holding member facing the fixed-side mold. In particular, since the ball retainers are provided in both the fixed side mold and the movable side mold, the centering of the fixed side molded sesame and the movable side molded sesame is more accurate.

  Therefore, it is possible to provide an injection mold for a plastic optical lens and a method for manufacturing the plastic optical lens, which have a simple structure and high molding accuracy as compared with the conventional one described in FIG.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of an injection mold according to the first embodiment, and FIG. 2 is an enlarged cross-sectional view of the vicinity of a ball retainer of the injection mold.

  First, the overall structure of the injection mold will be described with reference to FIG.

  A moving side lens sesame 2 is arranged inside the moving side outer sesame (moving side insert) 1, and a fixed side lens sesame 4 is arranged inside the fixed side outer sesame (fixed side insert) 3. The movable-side outer sesame 1 is separated from the fixed-side outer sesame 3 by opening and closing the mold.

  On the end face of the moving side outer sesame 1, there is provided a fitting recess 5 whose peripheral surface is tapered with the moving side lens sesame 2 as the center, and on the other hand, the fixed side lens sesame 4 is centered on the end face of the fixed side outer sesame 3. The fitting convex part 6 with which the surrounding surface became the taper shape is provided. The taper angle of the fitting concave portion 5 and the taper angle of the fitting convex portion 6 are substantially the same. As shown in the figure, when the mold is closed, the fitting convex portion 6 is inserted into the fitting concave portion 5 and when the insertion is completed. The peripheral surface of the fitting convex portion 6 is in close contact with the peripheral surface of the fitting concave portion 5.

  The lens sesame 2 and 4 have lens molding surfaces 2a and 4a having predetermined shapes at the tips thereof, whereby a cavity corresponding to the outer shape of the molded product is formed.

  Retainer accommodating portions 7 are respectively formed in the central portions of the outer sesame 1 and 3 into which the lens sesame 2 and 4 are inserted, and a ball retainer 8 is interposed there. As shown in FIG. 1, the ball retainer 8 includes a plurality of balls 9 arranged in five rows in the central axis direction, and a ball holding cylinder that rotatably holds the balls 9 on the peripheral wall at predetermined intervals. 10 is comprised.

  The ball 9 is made of, for example, bearing steel (hardness: HRC58), stainless steel (SUS440), and the like, and the ball holding cylinder 10 is made of various materials such as stainless steel, brass, hard synthetic resin, etc. High and light weight has a small motion inertia force, and is excellent in high-speed reciprocation in the axial direction (for example, reciprocation of the lens sesame 2 when protruding the lens sesame 2 from the outer sesame 1 to release the molded lens). . The arrangement of the balls 9 on the peripheral wall of the ball holding cylinder 10 includes five rows of staggered shapes (see FIG. 1), three rows of parallel shapes (see FIG. 2), and spiral shapes in the central axis direction. It is preferable to arrange in multiple rows in the direction.

  As shown in FIG. 2, a part of each ball 9 slightly protrudes from the outer peripheral surface and the inner peripheral surface of the ball holding cylinder 10, and a portion protruding from the outer peripheral surface of the ball holding cylinder 10 is the inner periphery of the outer sesame 1 (3). The portion that is in rolling contact with the surface and protrudes from the inner peripheral surface of the ball holding cylinder 10 is in contact with the outer peripheral surface of the lens sesame 2 (4).

  By using the ball 9 having a diameter slightly larger (for example, about several μm) than the gap X between the lens sesame 2 (4) and the outer sesame 1 (3) that holds the lens sesame 2 (4), the elasticity of the ball 9 is utilized. The central axis Y of the lens sesame 2 (4) and the outer sesame 1 (3) can be made coincident with each other, and the frames of the lens sesame 2 (4) and the outer sesame 1 (3) can be aligned. Can be ensured uniformly.

  It is desirable that the hardness of the ball 9 is slightly lower than the hardness of the outer sesame 1 and 3 and the lens sesame 2 and 4 with which the ball 9 rolls. By the rotation of the large number of balls 9, the lens sesame 2 (4) can move smoothly and stably in the axial direction with respect to the outer sesame 1 (3). In addition, by dispersing and holding a large number of balls 9 in the ball holding cylinder 10 in this way, there are few fluctuating loads and partial loads on the outer sesame 1, 3 and the lens sesame 2, 4, and the lens sesame 2 (4) is accurate. Straight movement is possible.

  The center axis Y of the outer sesame 1 and the lens sesame 2 is aligned with the center axis Y of the outer sesame 3 and the lens sesame 4 via the ball retainer 8, and the fitting recess 5 is formed around the lens sesame 2. Since the fitting convex portion 6 is formed around the lens sesame 4, the moving side lens sesame 2 and the fixed side lens sesame 4 are tapered by fitting the moving side outer sesame 1 and the fixed side outer sesame 3 to each other. Centering is inevitably performed. The optical lens 11 can be molded by injecting a molten transparent resin into a cavity formed by the lens molding surfaces 2a and 4a of the lens sesame 2 and 4, filling and holding the resin.

  In FIG. 1, reference numeral 24 denotes an adjustment sesame for adjusting the position of the lens sesame 2 and 4 in the axial direction.

  In this embodiment, the fitting concave portion 5 is provided on the moving-side outer sesame 1 and the fitting convex portion 6 is provided on the stationary-side outer sesame 3. On the contrary, the fitting convex portion 6 is provided on the moving-side outer sesame 1. A fitting recess 5 can also be provided in the fixed-side outer sesame 3.

  FIG. 3 is a sectional view of an injection mold according to the second embodiment of the present invention. In the figure, reference numeral 1 denotes a moving side outer sesame, and reference numeral 2 denotes a moving side lens sesame, which is held movably on the moving side outer sesame 1 via a ball retainer 8. Reference numeral 3 denotes a fixed-side outer sesame, and reference numeral 4 denotes a fixed-side lens sesame, which are integrated so that there is no clearance by being directly pressed into the fixed-side outer sesame 3 without a ball retainer.

  Reference numeral 12 denotes a guide bush, which is press-fitted into the fixed-side outer sesame 3 and integrated so that there is no clearance. A fitting recess 5 having a tapered surface on the peripheral surface is formed at the lower end opening of the guide bush 12. Is formed. Reference numeral 13 denotes a guide pin, which is press-fitted into the movable-side outer sesame 1 and integrated so that there is no clearance. The upper end portion of the guide pin 13 has a tapered surface on the peripheral surface, and the fitting recess The fitting convex part 6 which fits closely to 5 is formed.

  14 is a fixed side mounting plate, 15 is a fixed side template, 16 is a moving side template, 17 is a receiving plate, 18 is a spacer block, 19 is a moving side mounting plate, 20 is a protruding rod, 21 is an ejector pin, 22 is An ejector lock plate 23 is an ejector plate.

  In this embodiment, the guide bush 12 is press-fitted into the fixed-side outer sesame 3 and the guide pin 13 is press-fitted into the moving-side outer sesame 1, but the fitting recess 5 is formed integrally with the fixed-side outer sesame 3 or moved. The fitting convex part 6 can also be formed integrally with the side sesame 1.

  In this embodiment, the guide bush 12 (fitting recess 5) is provided on the fixed-side outer sesame 3 and the guide pin 13 (fitting protrusion 6) is provided on the moving-side outer sesame 1, but fixed on the contrary. It is also possible to provide the guide pin 13 (the fitting convex portion 6) on the side outer sesame 3 and the guide bush 12 (fitting concave portion 5) on the moving side outer sesame 1.

1 is a cross-sectional view of an injection mold according to a first embodiment of the present invention. It is an expanded sectional view near the ball retainer of the injection mold. It is sectional drawing of the injection mold which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the conventional injection mold.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movement side outer sesame 2 Movement side lens sesame 2a Molding surface of movement side lens sesame 3 Fixed side outer sesame 4 Fixed side lens sesame 4a Molding surface of fixed side lens sesame 5 Fitting recessed part 6 Fitting convex part 7 Retainer accommodating part 8 Ball retainer 9 Ball 10 Ball Holding Tube 11 Optical Lens 12 Guide Bush 13 Guide Pin

Claims (2)

A first mold and a second mold facing the first mold;
At least the first mold includes a first molding sesame having a molding surface, and a first holding member that holds the first molding sesame from the outside,
At least the second mold includes a second molding sesame having a molding surface, and a second holding member that holds the second molding sesame from the outside,
An injection mold, wherein a guide bush is provided on the first holding member, and a guide pin fitted to the guide bush is provided on the second holding member. Using the injection mold according to claim 1,
A method for producing an injection-molded article, comprising: joining the first mold and the second mold, and injecting and filling molten resin into a cavity formed between the first mold and the second mold.

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