JP3789447B2 - Injection mold and injection molding method - Google Patents

Description

  The present invention relates to an injection mold such as a plastic optical lens and an injection molding method.

  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. 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 for attaching it. 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.

  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 by fitting the taper guide 124 to the taper bush 109, an attempt is made to suppress misalignment between the fixed side lens insert 107 and the moving side lens insert 117.

In addition, regarding an injection mold, there are proposals as described in Patent Documents 1 to 4 as described below, for example.
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, 117 are located away from the lens inserts 107, 117. A plurality of members are interposed up to 117 so that the centering is performed indirectly.

  In order to attach the fixed side lens insert 107 to the fixed side plate 104, a slight clearance is provided 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. Moreover, since the fixed side lens insert 107 is fixed to the mounting plate 105 with the bolts 108, the fixed side lens insert 107 is biased.

  This is the same 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. Moreover, since the moving side lens insert 117 protrudes and is screwed by the tip 122b of the rod 122, the moving side 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. is there.

  An object of the present invention is to solve such problems of the prior art and provide an injection mold and an injection molding method having a simple structure and high molding accuracy.

In order to achieve the above object, the first means of the present invention comprises a stationary mold and a movable mold,
The moving side mold has a moving side forming sesame having a moving side forming surface, a moving side holding member for holding the moving side forming sesame from the outside, and a ball can be rotated with a space around a peripheral wall of the ball holding cylinder. It has a moving ball retainer that holds it,
The fixed-side mold has a fixed-side molded sesame having a fixed-side molded surface, a fixed-side holding member that holds the fixed-side molded sesame from the outside, and a ball that can rotate with a space around the peripheral wall of the ball holding cylinder. It has a fixed ball retainer that is held,
The moving side ball retainer is inserted between the moving side molded sesame and the moving side holding member,
The fixed side ball retainer is inserted between a fixed side molding sesame and a fixed side holding member,
Further, either one of the moving side holding member or the fixed side holding member is provided with a fitting recess having a tapered surface on the peripheral surface, and the other side of the fixed side holding member or the moving side holding member is provided on the peripheral surface. A fitting convex portion having a tapered surface and fitting with the fitting concave portion is provided.

  The second means of the present invention uses the injection mold of the first means, joins the fixed side mold and the moving side mold, and injects molten resin into a cavity formed between them. , Filled and molded.

  The present invention is configured as described above, and since the ball retainer is 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. is there. In addition, the fixed-side holding member and the moving-side holding member facing the fixed-side holding member are taper-fitted, so that the fixed-side mold and the moving-side mold are accurately centered. Therefore, it is possible to provide an injection mold and an injection molding method that have a simple structure and higher molding accuracy than 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.

  The end surface of the moving side outer sesame 1 is provided with a fitting recess 5 whose peripheral surface is tapered around the moving side lens sesame 2, while the fixed side lens sesame 4 is centered on the end surface of the fixed side outer sesame 3. A fitting convex portion 6 having a tapered peripheral surface 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, and the fitting convex portion 6 is inserted into the fitting concave portion 5 when the mold is closed as shown in FIG. The peripheral surface of the mating 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 large number of balls 9 arranged in five rows in the central axis direction, and a ball holding cylinder 10 that rotatably holds the balls 9 on a peripheral wall at a predetermined interval. Has been.

  The ball 9 is made of, for example, bearing steel (hardness: HRC58), stainless steel (SUS440) or the like, and the ball holding cylinder 10 is made of various materials such as stainless steel, brass, hard synthetic resin, etc., and is particularly high in rigidity and lightweight. The one having a small motion inertia force is excellent in high-speed reciprocation in the axial direction (for example, reciprocation of the lens sesame 2 when the lens sesame 2 is protruded 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 peripheral surface of the outer sesame 1 (3). The portion protruding 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 is little fluctuating load and uneven load on the outer sesame 1, 3 and the lens sesame 2, 4, and the lens sesame 2 (4) is accurately linearly moved. Is possible.

  The center axis Y of the outer sesame 1 and the lens sesame 2 is aligned through the ball retainer 8, the center axis Y of the outer sesame 3 and the lens sesame 4 are aligned, 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 aligned by taper fitting the moving side outer sesame 1 and the fixed side outer sesame 3. 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 and 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. A fitting recess 5 can also be provided in the 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. The fixed-side outer lens sesame is directly pressed into the fixed-side outer sesame 3 without a ball retainer so that there is no clearance.

  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 is formed at the lower end opening of the guide bush 12. Yes. Reference numeral 13 is a guide pin that is pressed into the moving side outer sesame 1 and integrated so that there is no clearance. The upper end of the guide pin 13 has a tapered surface on the peripheral surface, and is tightly connected to the fitting recess 5. The fitting convex part 6 which fits in 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 movable-side outer sesame 1, but the fitting recess 5 is formed integrally with the fixed-side outer sesame 3, The fitting convex part 6 can also be formed integrally with the outer sesame 1.

  Further, 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 movable-side outer sesame 1. It is also possible to provide the guide pin 13 (the fitting convex portion 6) on the sesame 3 and the guide bush 12 (the 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. 1 is a cross-sectional view of an injection mold according to a first embodiment of the present invention. It is sectional drawing of the conventional injection mold.

Explanation of symbols

  1: moving-side outer sesame, 2: moving-side lens sesame, 2a: moving-side lens sesame molding surface, 3: fixed-side outer sesame, 4: fixed-side lens sesame, 4a: fixed-side lens sesame molding surface, 5: fitting recess, 6: fitting convex part, 7: retainer accommodating part, 8: ball retainer, 9: ball, 10: ball holding cylinder, 11: optical lens, 12: guide bush, 13: guide pin.

Claims (2)

It has a fixed side mold and a moving side mold,
The moving side mold has a moving side forming sesame having a moving side forming surface, a moving side holding member for holding the moving side forming sesame from the outside, and a ball can be rotated with a space around a peripheral wall of the ball holding cylinder. It has a moving ball retainer that holds it,
The fixed-side mold has a fixed-side molded sesame having a fixed-side molded surface, a fixed-side holding member that holds the fixed-side molded sesame from the outside, and a ball that can rotate with a space around the peripheral wall of the ball holding cylinder. It has a fixed ball retainer that is held,
The moving side ball retainer is inserted between the moving side molded sesame and the moving side holding member,
The fixed side ball retainer is inserted between a fixed side molding sesame and a fixed side holding member,
Further, either one of the moving side holding member or the fixed side holding member is provided with a fitting recess having a tapered surface on the peripheral surface, and the other side of the fixed side holding member or the moving side holding member is provided on the peripheral surface. An injection mold having a taper surface and a fitting projection for fitting with the fitting recess. The injection mold according to claim 1 is used, the fixed mold and the movable mold are joined, and a molten resin is injected and filled in a cavity formed between the two molds. Injection molding method.

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