JP2018065281A - Multilayered molding lens and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered molding lens exhibiting excellent optical characteristics, which causes its surface layer not to produce an irregular change of molten resin viscosity, and to provide a manufacturing method of the same.SOLUTION: A multilayered molding lens of three or more layers (N layers) exposes gate marks of the gate formed by molding a first layer and a Nth layer to a lens outer surface, and does not expose gate marks of the gate formed by molding each layer of from a second layer to a (N-1)th layer to the lens outer surface and a lens surface. Further, the gate marks of the first layer and the Nth layer are adjacent to each other at the same place of a lens outer peripheral end face.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a multilayer molded lens and a method of molding and manufacturing the same.

  In multilayer molding, for example, as disclosed in Patent Document 1, an intermediate molded product as a first layer formed by a mold cavity having a minimum volume among a plurality of mold cavities having different volumes is larger in volume. Then, the second layer is laminated and molded to the mold cavity, and then the intermediate molded product is sequentially transferred to the mold cavities up to the Nth layer to laminate and mold each layer. And the gate trace of the gate which shape | molded the Nth layer is exposed to the outer surface of the lens manufactured by multilayer molding. On the other hand, the gate traces of the gates formed from the first layer to the (N-1) th layer are not exposed to the outer surface of the lens because they are melted and disappeared in the subsequent layer forming.

JP 2013-107229 A

  However, since the first layer formed by the technique of Patent Document 1 and having no gate trace exposed is formed through a direct gate such as a hot runner nozzle, the molten resin at the tip of the hot runner nozzle forms a lens surface. It remains as cold slug in the first layer. Also, molding defects such as weld marks and jetting are likely to occur around the gate. Irregular changes in the viscosity of the molten resin due to such cold slugs and molding defects cause deterioration in the appearance quality of the lens and the optical characteristics of the lens.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a multilayer molded lens having good optical characteristics that does not cause irregular changes in the viscosity of the molten resin in the surface layer, and a method for manufacturing the same. .

  In order to achieve the above object, the invention according to claim 1, wherein the multilayer molded lens having three or more layers (N layers) has a gate mark of a gate formed with the first layer and the Nth layer formed on the outer surface of the lens. The gate traces of the gates formed by exposing and forming the layers from the second layer to the (N-1) th layer are not exposed to the lens outer surface and the lens surface.

  In this multilayer molded lens, the gate trace of the gate formed with the first layer and the Nth layer is exposed on the outer surface of the lens, and the gate trace of the gate formed with each layer from the second layer to the (N-1) th layer is formed. Do not expose to the lens outer surface or lens surface. Therefore, an irregular change in the melt resin viscosity due to molding defects such as cold slug, flow mark, jetting, etc. does not occur in the important part of the lens, so that the multilayer molded lens has excellent optical characteristics. There is an effect.

  According to the second aspect of the present invention, the gate traces of the first layer and the Nth layer are adjacent to each other at the same position on the outer peripheral end surface of the lens.

  According to this configuration, it is possible to cut the gate at once by integrating the two gate marks, and the productivity is improved, and the gate periphery of the first layer is melted by the molten resin of the Nth layer. The peripheral molten resin viscosity is made uniform, and the lens has an excellent effect of improving the appearance quality and optical characteristics of the lens.

  According to a third aspect of the present invention, an intermediate molded body as a first layer molded by a molding cavity having a minimum volume among a plurality of molding cavities having mutually different volumes is transferred to a molding cavity having a larger volume to form a second layer. Are laminated or insert molded, and thereafter, the intermediate molded body is sequentially transferred to the respective layer forming cavities up to the Nth layer, and laminated molding or insert molding is performed to manufacture a multilayer molded lens having three or more layers (N layers). A method of forming a first layer and an Nth layer by exposing a gate mark on the outer surface of the lens, and a layer forming step or an insert molding step of forming each of the other layers excluding the first layer and the Nth layer And a melting step of melting the gate marks generated in the layer forming step or the insert molding step so as not to appear on the lens surface in the subsequent layer forming.

  According to this manufacturing process, irregular changes in the viscosity of the molten resin due to cold slugs and molding defects do not occur in important portions of the first layer and the Nth layer that form the optical surface of the lens. This provides an excellent effect of improving the optical characteristics of the lens. In addition, in the inner layers from the second layer to the (N-1) th layer, cold slugs etc. melt and disappear together with the gate traces, so there is no effect on the optical characteristics, and the direct gate improves productivity and molds. There is an excellent effect that the structure can be simplified.

  According to a fourth aspect of the present invention, the gate marks of the first layer and the Nth layer are provided adjacent to the same portion of the lens outer peripheral end surface.

  According to this configuration, it is possible to cut the gate at once by integrating the two gate marks, and the productivity is improved, and the gate periphery of the first layer is melted by the molten resin of the Nth layer. The peripheral molten resin viscosity is made uniform, and the lens has an excellent effect of improving the appearance quality and optical characteristics of the lens.

  According to a fifth aspect of the present invention, the manufacturing process further includes a step of cooling the intermediate molded body with a cooling cavity provided adjacent to the one or more molding cavities in the transfer direction of the intermediate molded body.

  According to this manufacturing process, even if the layer is thicker than the other layers, the layer is sufficiently cooled, and the optical characteristics of the lens are improved by stabilizing the layer shape. Play. In addition, by cooling the intermediate molded body with the cooling cavity, the cooling time set for a relatively long time can be shortened corresponding to the layer with the largest wall thickness when the cooling cavity is not provided. There is an excellent effect that the time can be shortened and the productivity can be improved.

  The invention according to claim 6 is that the cooling cavity does not have a gate which is an injection port of molten resin.

  According to this configuration, there is an excellent effect that the mold apparatus can be configured easily.

  According to a seventh aspect of the present invention, there is provided a method of manufacturing a multilayer molded lens, the step of carrying an insert molded body that integrally constitutes each of the layers other than the first layer and the Nth layer into a mold apparatus and disposing it. An insert molding step of simultaneously molding the first layer and the Nth layer exposing the gate traces on the lens outer surface and surrounding the insert molded body with the first layer and the Nth layer, and the insert molding in the insert molding step. And a melting step of melting the surface of the insert molded body so that unevenness and gate traces on the body surface do not appear on the lens surface.

  According to this manufacturing process, since irregular changes in the viscosity of the molten resin such as cold slug do not occur in the important parts of the first layer and the Nth layer forming the lens surface, the appearance quality of the lens is improved and the lens Optical characteristics are improved. In addition, since the irregularities and gate traces on the surface of the insert molded body are melted and disappeared, the optical characteristics are not affected. Furthermore, since the molding cycle of the insert molded body can be made relatively short, there is an excellent effect that productivity can be improved.

  According to the eighth aspect of the present invention, when the first layer or the Nth layer is molded, the lens surface which is a surface of an important portion of the first layer or the Nth layer is transferred by transferring fine irregularities formed on the cavity surface. To form a fine uneven shape.

  According to this manufacturing process, the gates for the first layer and the Nth layer are set to have a relatively large cross-sectional area, so that the molding pressure of the molten resin can be uniformly transmitted to the molding cavity with a low pressure loss. it can. Therefore, the fine unevenness is accurately transferred and molded to the first layer or the Nth layer, and an excellent effect is obtained that a fine unevenness shape as close as possible to the fine unevenness can be formed on the lens surface.

It is a fragmentary sectional perspective view which expands and shows the multilayer molded lens shape | molded with the manufacturing method which concerns on 1st embodiment of this invention. It is a center sectional side view of the metal mold apparatus which shape | molds the multilayer molded lens shown in FIG. It is a top view by the III-III arrow of the metal mold apparatus shown in FIG. It is a top view by the IV-IV arrow of the metal mold | die apparatus shown in FIG. It is process drawing of the lamination molding which shows the manufacturing method which concerns on 1st embodiment of this invention. It is a partial cross-sectional perspective view which expands and shows the multilayer molded lens shape | molded by the manufacturing method which concerns on 2nd embodiment. FIG. 7 is a central sectional side view showing a mold apparatus together with a multilayer molded lens in a molded state (shown in FIG. 6). It is process drawing of insert molding and lamination molding showing the manufacturing method concerning a second embodiment. It is a center section side view showing a metallic mold device which performs a manufacturing method concerning a third embodiment of the present invention with a multilayer molded lens after fabrication. It is process drawing of insert molding which shows the manufacturing method which concerns on 3rd embodiment of this invention. It is the elements on larger scale of the cavity surface which shows the shape of the fine unevenness | corrugation in a modification. It is a partial expanded sectional view of the cavity surface which shows the other shape of the fine unevenness | corrugation in a modification.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. However, in all the drawings in this specification, portions corresponding to each other or portions having similar functions are denoted by the same reference numerals, and description of the overlapping portions will be omitted as appropriate.

[First embodiment]
A multilayer molded lens 20 shown in FIG. 1 is suitably used in a vehicle headlamp or the like, and is a thick lens having a maximum thickness of 12 mm or more due to required light collecting characteristics. When such a thick plastic lens is molded in a single layer as a conventional molding method, sink marks (deformation) generated in the maximum thickness portion have a great influence on the optical characteristics. Therefore, by introducing multilayer molding, the maximum wall thickness can be divided and distributed to each layer, the thickness of each layer is reduced, cooling time is shortened, production efficiency is improved, and generation of sink marks is suppressed. As a result, it is possible to produce a thick lens with good optical characteristics. This effect becomes significant in multilayer molding of three layers (N = three) or more.

  The mold apparatus 14 shown in FIG. 2 includes a first cavity block 3 and a second cavity block 4 that are matched with each other on a mold matching surface 18 and laminates and molds five layers (N = 5) of multilayer molded lenses 20. The mold device 14 is attached to a mold clamping device 15 including the first mold plate 1 and the second mold plate 2. An injection molding machine is configured by an injection device (not shown) and a mold clamping device 15 that generate and supply molten resin.

  As shown in FIGS. 2 and 3, cavity surfaces 5 a to 5 f are formed on the surface of the first cavity block 3 that faces the second cavity block 4.

  The cavity surface 5a is a substantially flat surface as shown in FIGS. As shown in FIG. 3, the cavity surface 5b is formed of a recess having the smallest outer diameter, depth, and curvature among the cavity surfaces 5b to 5d and 5f. As shown in FIG. 3, the cavity surface 5 c has recesses that are all larger than the outer diameter, depth, and curvature of the cavity surface 5 b. As shown in FIGS. 2 and 3, the cavity surface 5 d has recesses that are all larger than the outer diameter, depth, and curvature of the cavity surface 5 c. As shown in FIG. 3, the cavity surface 5e is formed of a recess having the same outer diameter, depth and curvature as the outer diameter, depth and curvature of the cavity surface 5d. As shown in FIG. 3, the cavity surface 5f is composed of a concave portion having the same outer diameter as that of the cavity surface 5a and a depth and curvature that are both larger than the depth and curvature of the cavity surface 5d.

  As shown in FIGS. 2 and 4, cavity surfaces 6 a to 6 f are formed on the surface of the second cavity block 4 facing the first cavity block 3. The cavity surfaces 6a to 6f are all the same in outer diameter, depth, and curvature, and have concave portions having the same shape.

  The cavity surfaces 5a to 5f and the cavity surfaces 6a to 6f are arranged so that the centers of the circles are equally divided on two circumferences set to the same diameter in each group. Therefore, when the first cavity block 3 and the second cavity block 4 are mold-matched by the mold-matching surface 18, the centers of the cavity surfaces 5a to 5f and the centers of the cavity surfaces 6a to 6f are aligned with each other. A cavity 7a, a molding cavity 7b, a molding cavity 7c, a molding cavity 7d, a cooling cavity 7e, and a molding cavity 7f are formed.

  As shown in FIGS. 1 to 4, the molding cavity 7 a is for the first layer 21, and molten resin is injected through the gate 8 a provided on the second cavity block 4 side of the die-matching surface 18 on the outer peripheral end surface thereof. Is done. As shown in the figure, the nozzle portion of the hot runner 10 is in contact with the gate 8a. Further, since the cross-sectional area of the gate 8a is set to be relatively large, the molding pressure of the molten resin can be uniformly transmitted to the molding cavity with a low pressure loss. Therefore, the shape of the molding cavity 7a can be faithfully transferred to mold the first layer 21 which is the surface layer, so that a multilayer molded lens with good optical characteristics can be molded. Since the first layer 21 has an annular flange 16 that protrudes in the shape of a hat on the outer periphery of the important portion 17 that is the optical surface of the lens, cold slug flows from the nozzle portion of the hot runner 10, Even if a molding defect such as jetting occurs, it remains in the flange 16. And since they do not flow into the important part 17 of the multilayer molded lens 20, a multilayer molded lens with good optical characteristics can be molded.

  The second cavity block 4 is rotatable in the direction of the arrow in FIG. 4 (counterclockwise direction) with the center of the circumference having the centers of the circles of the cavity surfaces 6a to 6f equally divided. The intermediate molded body formed in the molding cavity 7 a and remaining on the cavity surface 6 a of the molding cavity 7 a as the first layer 21 is transferred to the molding cavity 7 b by the rotation of the second cavity block 4. A substantial cavity formed by the intermediate molded body as the first layer 21 and the cavity surface 5 b is for the second layer 22. The volume of the substantial cavity is obtained by subtracting the volume of the molding cavity 7a from the volume of the molding cavity 7b. That is, the volume of the molding cavity 7b is substantially larger than the volume of the molding cavity 7a by the volume of the cavity. Molten resin is injected into the substantial cavity through the gate 8b. The nozzle portion of the hot runner 11 is in contact with the gate 8b.

  The hot runners 10 and 11 are runners that keep the molten resin existing therein in a molten state by keeping the temperature thereof with a heater (not shown). The hot runners 10 and 11 are provided at the tips of the hot runners 10 and 11 to open or close the nozzles that are in contact with the gates 8a to 8d and 8f with a mechanically or thermally operated valve to flow or block the molten resin. Therefore, since the hot runners 10 and 11 can take out only the molded product while leaving the runner part in the mold apparatus, a process of crushing or reusing the solidified runner is not necessary and complicated. Since arrangement | positioning of a runner can be avoided, the structure of a mold apparatus can be simplified. A sprue 13 communicates with and is connected to the hot runner 12 that communicates with the hot runners 10 and 11 at a right angle. The nozzle of the injection device comes into contact with the sprue 13 and the molten resin is supplied.

  The intermediate molded body formed in the molding cavity 7 b and remaining on the cavity surface 6 b of the molding cavity 7 b as the first layer 21 and the second layer 22 is transferred to the molding cavity 7 c by the rotation of the second cavity block 4. The substantial cavity formed by the intermediate molded body as the first layer 21 and the second layer 22 and the cavity surface 5 c is for the third layer 23. The volume of the substantial cavity is obtained by subtracting the volume of the molding cavity 7b from the volume of the molding cavity 7c. That is, the volume of the molding cavity 7c is substantially larger than the volume of the molding cavity 7b by the volume of the cavity. Molten resin is injected into the substantial cavity through the gate 8c. The nozzle portion of the hot runner 11 is in contact with the gate 8c.

  The intermediate molded body formed in the molding cavity 7c and remaining on the cavity surface 6c of the molding cavity 7c as the first layer 21, the second layer 22, and the third layer 23 is transferred to the molding cavity 7d by the rotation of the second cavity block 4. The The substantial cavity formed by the intermediate molded body as the first layer 21, the second layer 22, and the third layer 23 and the cavity surface 5 d is for the fourth layer 24. The volume of the substantial cavity is obtained by subtracting the volume of the molding cavity 7c from the volume of the molding cavity 7d. That is, the volume of the molding cavity 7d is substantially larger than the volume of the molding cavity 7c by the volume of the cavity. Molten resin is injected into the substantial cavity through the gate 8d. The nozzle portion of the hot runner 11 is in contact with the gate 8d.

  The intermediate molded body formed in the molding cavity 7d and remaining on the cavity surface 6d of the molding cavity 7d as the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24 is cooled by the rotation of the second cavity block 4. It is transferred to the cavity 7e. That is, the cooling cavity 7e is provided adjacent to the molding cavity 7d in the transfer direction of the intermediate molded body. Since the cooling cavity 7e has the same dimensions and the same shape as the molding cavity 7d, the cooling cavity 7e is formed by the intermediate molded body as the first layer 21, the second layer 22, the third layer 23 and the fourth layer 24 and the cavity surface 5e. The volume of the real cavity is zero. In the cooling cavity 7e, lamination molding is not performed, and the intermediate molded body is only cooled. Therefore, the cooling cavity 7e does not have a gate which is an injection port for molten resin.

  When the volume and shape of each layer are not uniform and the thickness of the fourth layer 24 is larger than the other layers as shown in FIG. 1, the molten resin of the fourth layer becomes insufficiently cooled, and the molten resin There is a concern that the optical characteristics of the lens will deteriorate because the solidification of the lens is delayed and the surface shape becomes unstable. Further, in order to avoid this, when the cooling time of the molding cycle is set to be relatively long corresponding to the cooling time of the fourth layer 24, the molding cycle time is significantly delayed, leading to a decrease in production efficiency. By providing the cooling cavity 7e, the fourth layer 24 is sufficiently cooled, the optical characteristics of the lens are improved by stabilizing the layer shape, and the cooling cavity 7e is used to cool the intermediate molded body. In the case where 7e is not provided, the cooling time set for a relatively long time corresponding to the fourth layer 24 having the largest thickness can be shortened, so that the molding cycle time can be shortened and the productivity can be improved. it can.

  The intermediate molded body cooled by the cooling cavity 7e and remaining on the cavity surface 6e of the cooling cavity 7e as the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24 is molded by the rotation of the second cavity block 4. It is transferred to the cavity 7f. The substantial cavity formed by the intermediate molded body as the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24 and the cavity surface 5f is for the fifth layer 25. The volume of the substantial cavity is obtained by subtracting the volume of the molding cavity 7d from the volume of the molding cavity 7f. That is, the volume of the molding cavity 7f is substantially larger than the volume of the molding cavity 7d by the volume of the cavity. Molten resin is injected into the substantial cavity through the gate 8f. The nozzle portion of the hot runner 10 is in contact with the gate 8f.

  The gate 8f is provided on the first cavity block 3 side of the die matching surface 18 on the outer peripheral end surface of the molding cavity 7f. Since the cross-sectional area of the gate 8f is set to be relatively large, the molding pressure of the molten resin can be uniformly transmitted to the molding cavity with a low pressure loss. Therefore, the shape of the molding cavity 7f can be faithfully transferred to mold the fifth layer as the surface layer, and a multilayer molded lens with good optical characteristics can be molded. Further, since the fifth layer 25 has an annular flange 16 protruding like a hat collar on the outer periphery of the important portion 17 which is the optical surface of the lens, cold slug flows or flows from the nozzle portion of the hot runner 10. Even if molding defects such as marks and jetting occur, they remain in the flange 16. And since they do not flow into the important part 17 of the multilayer molded lens 20, a multilayer molded lens with good optical characteristics can be molded.

  As shown in FIG. 3, the gate 8a and the gate 8f are respectively on a straight line connecting the centers of the circles of the molding cavity 7a and the molding cavity 7f and the center of the circle having the two center points on the circumference. Is provided. The gate 8 a is provided on the second cavity block 4 side in contact with the mold matching surface 18, and the gate 8 f is provided on the first cavity block 3 side in contact with the mold matching surface 18. Therefore, as shown in FIG. 1 after the fifth layer is formed, the gate mark 9a and the gate mark 9f generated by gate-cutting the gate 8a and the gate 8f are semi-circular or semi-elliptical bases, respectively. Are adjacent to each other and exposed at the same location on the outer peripheral end surface of the multilayer molded lens 20. Note that if one or both of the first layer gate and the fifth layer gate are not provided on the straight line, the gate marks of both gates are not integrated. However, even when both the first layer gate and the fifth layer gate are not provided on the straight line, both gates are provided when both are provided at the same position on the outer periphery of each cavity with respect to the straight line. The gate marks are integrated.

  As shown in FIG. 1, the gate marks 9a and 9f are semicircles or semi-elliptical. That is, the cross-sectional shapes of the gate 8a and the gate 8f are also semicircular or semielliptical. However, the cross-sectional shape of the gate may be a shape such as a rectangle, a trapezoid, a circle, or an ellipse as long as one side or one point is in contact with each other regardless of a semicircle or a semi-ellipse. In this way, the gate cut is performed once and facilitated by integrating the two gate traces, and the periphery of the gate of the first layer is melted by the molten resin of the fifth layer (Nth layer). As a result, the molten resin viscosity around the gate is made uniform and the appearance quality and optical characteristics of the lens are improved.

  Lamination molding of a multilayer molded lens is carried out by repeating one molding cycle of the injection molding machine a number of times corresponding to the number of laminations. In the present embodiment, since the five-layer multilayer molded lens 20 is molded by the mold apparatus 14 having five molding cavities and one cooling cavity, six molding cycles are required.

  Next, one molding cycle of the injection molding machine will be described.

  The mold clamping device 15 brings the second mold plate 2 close to the first mold plate 1 to close the mold, and molds the first cavity block 3 and the second cavity block 4. The mold clamping device 15 clamps the first cavity block 3 and the second cavity block 4 via the first mold plate 1 and the second mold plate 2.

  The injection device causes the nozzle to contact the sprue 13 and then simultaneously supplies the generated molten resin to the molding cavities 7a to 7d and 7f via the sprue 13 and the hot runners 12, 10, and 11 to execute the injection process. To do. Details of the injection process will be described later.

  The mold clamping device 15 starts the cooling process by starting the cooling time timer after the end of the injection process while continuing the pressure clamping of the first cavity block 3 and the second cavity block 4. The injection device also initiates a plasticizing process that produces molten resin for the next molding cycle.

  The mold clamping device 15 ends the cooling process when the preset cooling time of the cooling time timer has elapsed.

  The mold clamping device 15 opens the mold by separating the second mold plate 2 from the first mold plate 1. At this time, each intermediate molded body is released from each cavity surface of the first cavity block 3, and the gate of each layer is gate-cut from each nozzle portion of the hot runner to leave each gate trace.

  The mold clamping device 15 rotates the second cavity block 4 to transfer each intermediate molded body to the molding cavity or cooling cavity of the next layer.

  The intermediate molded body as a finished product including the fifth layer attached to the cavity surface 6f of the second cavity block 4 is released from the cavity surface 6f by the ejecting device, and is then transferred from the mold device 14 to the outside by the removing device. Be transported.

  Since the injection process of lamination molding is performed over each molding cycle, each injection process is explained in order of lamination based on FIG.

  (S1) The molten resin supplied from the injection device sequentially flows through the sprue 13, hot runner 12, hot runner 10, and gate 8 a, and then injection-fills the molding cavity 7 a for the first layer to form the first layer 21. Is formed. At this time, the gate 8a provided on the end face of the flange portion 16 leaves a gate mark 9a at that position. The gate mark 9 a is exposed on the outer peripheral end surface of the multilayer molded lens 20.

  (S2) In the next molding cycle, the molten resin supplied from the injection device sequentially flows through the sprue 13, the hot runner 12, the hot runner 11, and the gate 8b, and then the intermediate molded body and the cavity as the first layer 21 The second layer 22 is laminated and formed on the first layer 21 by injection filling the substantial cavity for the second layer composed of the surface 5b. At this time, the gate 8b of the cavity surface 5b which is the surface of the second layer 22 leaves a gate mark 9b at that position.

  (S3) In the next molding cycle, the molten resin supplied from the injection device sequentially flows through the sprue 13, hot runner 12, hot runner 11, and gate 8 c, and then as the first layer 21 and the second layer 22. A third layer 23 is formed on the second layer 22 by injection filling a substantial cavity for the third layer composed of the intermediate molded body and the cavity surface 5c. At this time, the gate 8c of the cavity surface 5c that becomes the surface of the third layer 23 leaves a gate mark 9c at that position. The gate mark 9b generated in the previous molding cycle is melted by lamination molding of the third layer 23 so as not to be exposed on the lens surface.

  (S4) In the next molding cycle, the molten resin supplied from the injection device sequentially flows through the sprue 13, the hot runner 12, the hot runner 11, and the gate 8d, and then the first layer 21, the second layer 22, and the first layer. A fourth layer 24 is laminated on the third layer 23 by injection filling a substantial cavity for the fourth layer composed of the intermediate formed body as the third layer 23 and the cavity surface 5d. At this time, the gate 8d of the cavity surface 5d serving as the surface of the fourth layer 24 leaves a gate mark 9d at that position. The gate mark 9c generated in the previous molding cycle is melted by lamination molding of the fourth layer 24 so as not to be exposed on the lens surface.

  (S5) In the next molding cycle, the intermediate molded body composed of the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24 generated in the previous molding cycle is cooled in the cooling cavity 7e. .

  (S6) In the next molding cycle, the molten resin supplied from the injection device sequentially flows through the sprue 13, the hot runner 12, the hot runner 10, and the gate 8f, and then the first layer 21, the second layer 22 and the third layer The fifth layer 25 is laminated and formed on the fourth layer 24 by injection filling a substantial cavity for the fifth layer composed of the intermediate molded body as the layer 23 and the fourth layer 24 and the cavity surface 5f. At this time, the gate mark 9d generated in the previous molding cycle is melted by lamination molding of the fifth layer 25 so as not to be exposed on the lens surface. Further, the gate 8f provided on the end face of the flange portion 16 leaves a gate mark 9f at that position. The gate mark 9 f is exposed on the outer peripheral end surface of the multilayer molded lens 20.

  As is clear from the above detailed description, the manufacturing process of the multilayer molded lens 20 in the first embodiment includes a laminated molding process in which the first layer and the Nth layer are formed by exposing gate marks to the lens outer surface, The layer molding process or insert molding process for forming each layer other than the first layer and the Nth layer, and the gate marks generated in the layer molding process or the insert molding process appear on the lens surface in the molding after the next layer. And a melting step of melting so as not to occur. Therefore, irregular changes in the viscosity of the molten resin such as cold slug do not occur in the important parts of the first layer and the fifth layer forming the lens surface, so that the appearance quality of the lens is improved and the optical characteristics of the lens are improved. . Also, in the inner layers from the second layer to the fourth layer, cold slug etc. melts and disappears along with the gate traces, so there is no effect on the optical properties, and direct gates improve productivity and simplify the die structure Can be planned.

  In the first embodiment, the gate marks 9a and 9f of the first layer and the fifth layer are provided adjacent to the same location on the outer peripheral end surface of the lens. Therefore, it is possible to cut the gate at once by integrating the two gate marks, and the productivity is improved, and the molten resin around the gate is melted around the gate of the first layer with the molten resin of the fifth layer. The viscosity is made uniform and the appearance quality and optical characteristics of the lens are improved.

  Moreover, the manufacturing process of the multilayer molded lens 20 in the first embodiment further includes a step of cooling the intermediate molded body with the cooling cavity 7e provided adjacent to the molding cavity 7d in the transfer direction of the intermediate molded body. Therefore, even when the fourth layer is thicker than the other layers, the layer is sufficiently cooled, and the optical characteristics of the lens are improved by stabilizing the layer shape. In addition, by cooling the intermediate molded body with the cooling cavity 7e, the cooling time set to a relatively long time can be shortened corresponding to the fourth layer having the largest wall thickness when the cooling cavity 7e is not provided. Therefore, the molding cycle time can be shortened and productivity can be improved.

  Further, in the first embodiment, the cooling cavity 7e does not have a gate that is an injection port of the molten resin, so that the mold apparatus can be configured easily.

[Second Embodiment]
The multilayer molded lens 20a shown in FIG. 6 is manufactured by insert molding so that the number N of multilayers is limited to three and the inserted second layer 22 is surrounded by the first layer 21 and the third layer 23. It is. The multilayer molded lens 20a includes an important portion 17 that is an optical surface of the lens, and an annular flange portion 16 that protrudes in the shape of a hat collar on the outer periphery thereof.

  As shown in FIG. 7, the mold apparatus 14a attached to the mold clamping apparatus 15 similar to that of the first embodiment includes a first cavity block 3a and a second cavity block 4a that perform mold matching on the mold matching surface 18. Become.

  On the mold matching surface 18 of the first cavity block 3 a, a cavity surface 5 g and a cavity surface 5 h are engraved on the center line of the mold matching surface 18. On the mold matching surface 18 of the second cavity block 4a, the cavity surface 6g and the cavity surface 6h are engraved on the center line of the mold matching surface 18 so as to face the cavity surface 5g and the cavity surface 5h, respectively. The second cavity block 4a is rotated or rotated every 180 degrees. Therefore, the cavity surface 6g alternately opposes the cavity surface 5g and the cavity surface 5h, and the cavity surface 6h alternately opposes the cavity surface 5h and the cavity surface 5g.

  The cavity surface 5g and the cavity surface 6g face each other and die match, thereby forming a molding cavity 7g. The cavity surface 5h and the cavity surface 6h face each other and are mold-matched to form a molding cavity 7h. The cavity surface 6g is the same as the cavity surface 6h in its outer diameter, depth, and curvature. The cavity surface 5g has the same outer diameter as the cavity surface 5h, but is configured to be smaller than the cavity surface 5h in depth and curvature.

  A gate 8g is provided at the outer peripheral end of the molding cavity 7g, corresponding to the end face 16 of the lens flange 16 and adjacent to the mold matching surface 18. A gate 8h is provided at the outer peripheral end portion of the molding cavity 7h, corresponding to the lens flange 16 and adjacent to the mold matching surface 18. The hot runners 10 and 12 have the same functions, operations, and effects as those of the first embodiment, and thus detailed descriptions thereof are omitted.

  Since the gates 8g and 8h have a relatively large cross-sectional area, the molding pressure of the molten resin can be uniformly transmitted to the molding cavity with a low pressure loss. Therefore, since the first layer 21 and the third layer 23 which are the surface layers can be molded by faithfully transferring the shape of the molding cavity, the multilayer molded lens 20a with good optical characteristics can be molded. Since the first layer 21 and the third layer 23 have an annular flange 16 projecting like a hat collar on the outer periphery of the important portion 17 which is an optical surface of the lens, cold slug flows from the nozzle portion of the hot runner 10. Even if a molding defect such as a flow mark or jetting occurs, it remains in the flange 16. Since they do not flow into the important part 17 of the multilayer molded lens 20a, the multilayer molded lens 20a with good optical characteristics can be molded.

  Next, a method for manufacturing the multilayer molded lens 20a will be described with reference to FIGS.

  As shown in FIG. 7, the mold apparatus 14a molds the first layer 21 with the molding cavity 7g and molds the third layer 23 with the molding cavity 7h. After this molding, the mold device 14a is opened, and the multilayer molded lens 20a molded in the molding cavity 7h is gate-cut and released from the cavity surface 6h.

  After the second cavity block 4a is rotated 180 degrees, the mold is closed, whereby the cavity surface 6g to which the first layer 21 is adhered is opposed to the cavity surface 5h to form a mold cavity 7j. Then, the cavity surface 6h from which the multilayer molded lens 20a has been released faces the cavity surface 5g and is mold-matched to form a first molding cavity 7i.

  (S11) Molten resin is injected and filled into the first molding cavity 7i through the sprue 13, the hot runner 10, and the gate 8g, and the first layer 21 is molded. As shown in FIG. 6, the gate mark 9g of the gate 8g formed with the first layer 21 is exposed on the outer peripheral end face of the multilayer molded lens 20a.

  (S12) After the mold is opened, the second cavity block 4a is rotated or rotated 180 degrees, whereby the first layer 21 molded in the molding cavity 7i is transferred to the molding cavity 7h.

  (S13) In the mold open state, the insert molded body as the second layer 22 molded in advance is placed on the opened surface of the first layer 21 attached to the cavity surface 6h of the molding cavity 7h by a robot or the like. . In order to easily execute this step, the mold clamping device 15 is preferably a vertical mold in which the mold matching surface 18 is horizontal. The second layer 22 is an insert-molded body that is pre-molded so that the outer edge dimension is smaller than that of the first layer 21 by injection molding, compression molding, or the like using the same resin material as the first layer 21. is there. Therefore, the second layer 22 may or may not have a gate mark. When the second layer 22 has a gate mark, the gate mark is preferably provided on the surface of the second layer 22 that does not contact the first layer 21. In this way, the gate trace is melted and disappears when the third layer is laminated. Further, the second layer 22 may be formed of multiple layers instead of a single layer.

  (S14) The molten resin is injected and filled into the molding cavity 7h having a larger outer edge size than the second layer 22 through the sprue 13, the hot runner 10, and the gate 8h. The third layer 23 is laminated and formed on the surface of the second layer 22 that does not contact the first layer 21 and the outer peripheral surface of the first layer 21 that does not contact the second layer 22. Thereby, the second layer is surrounded between the first layer and the third layer. FIG. 7 shows this state. As shown in FIG. 6, the gate mark 9h of the gate 8h formed with the third layer 23 is exposed on the outer peripheral end surface of the multilayer molded lens 20a. Although the gate mark 9h is exposed adjacent to the gate mark 9g at the same location on the outer peripheral end surface of the lens, the gates 8g and 8h may be disposed so as to be exposed at locations separated from each other.

[Third embodiment]
The N-layer multilayer molded lens manufacturing system according to the third embodiment includes a molding apparatus (not shown) that molds the insert molded body 26 by the method described in the first embodiment and a mold apparatus 14b shown in FIG. And a mold clamping device 15. The insert molded body 26 molded by the molding apparatus is carried into the mold apparatus 14b, disposed at a predetermined position in the cavities 7k and 7l, and then simultaneously injected and filled to form the first layer 21 and the third layer. 23 (Nth layer).

  Although the insert molded body 26 is shown as a single layer in FIG. 9 for convenience of illustration, it is preferably a multilayer of up to (N-2) layers. Even if the insert molded body 26 is a multilayer, the layers are in close contact with each other. Since the insert molded body 26 is surrounded by the first layer 21 and the third layer 23 in a subsequent process, it is preferable to mold the insert molded body 26 with a relatively short cooling time. As a result, the production efficiency is improved, but slight unevenness due to sink marks or the like occurs on the surface of the insert molded body 26. Moreover, the gate trace when the surface layer is molded may be exposed on the surface of the insert molded body 26.

  As shown in FIG. 9, the mold apparatus 14b includes a first cavity block 3b and a second cavity block 4b. A cavity 7k is formed by the cavity surface 5i of the first cavity block 3b and the cavity surface 6i of the second cavity block 4b, and the multilayer molded lens 20b is molded by the cavity 7k. A cavity 7l is formed by the cavity surface 5j of the first cavity block 3b and the cavity surface 6j of the second cavity block 4b, and the multilayer molded lens 20b is also molded by the cavity 7l. Since the cavity 7k and the cavity 7l have the same shape and the same dimensions, the two multilayer molded lenses 20b can be molded in one molding cycle. The number of the plurality of cavities can be arbitrarily changed according to the molding cycle time of the molding apparatus for the insert molded body 26.

  As described above, the gates 8i and 8j of the cavity 7k for molding the multilayer molded lens 20b are separated in the diameter direction, and the gates 8i and 8j of the cavity 7l are adjacent to each other. Therefore, the multilayer molded lens 20b has a structure in which the gate marks 9i and 9j are separated in the diameter direction and a structure in which the gate marks 9i and 9j are adjacent to each other. Although not shown, the multilayer molded lens 20b includes an important portion 17 and a flange portion 16 as in the multilayer molded lens 20 of the first embodiment and the multilayer molded lens 20a of the second embodiment.

  In order to form a space for the first layer 21 and the third layer 23, the insert molded body 26 is held by a side gate or a dummy tab included in the insert molded body 26 at substantially the center of each of the cavity 7k and the cavity 7l. It is arranged so that.

  A gate 8i is connected to the space for the first layer 21 of the cavity 7k, and a sprue 27 is connected to the gate 8i. The sprue 27 is opened at the end face of the second cavity block 4b, and a nozzle of the first injection device (not shown) is in contact therewith. A gate 8 i is connected to the space for the first layer 21 of the cavity 7 l, and the gate 8 i is connected to the sprue 27 by a runner 29. The runner 29 is appropriately provided so as not to interfere around the cavity 7k in the second cavity block 4b.

  A gate 8j is connected to the space for the third layer 23 of the cavity 7k, and hot runners 10 and 12 provided as necessary are connected to the gate 8j. A gate 8j is connected to the space for the third layer 23 of the cavity 7l, and hot runners 10 and 12 are connected to the gate 8j. A sprue 28 is connected to the hot runner 12. The sprue 28 is open on the side surface of the first template 1, and a nozzle of a second injection device (not shown) is in contact therewith.

  Next, a method for manufacturing the multilayer molded lens 20b will be described with reference to FIGS.

  (S21) The insert molded body 26 formed by the molding apparatus with the other layers except the first layer 21 and the third layer 23 (Nth layer) being integrally formed is carried into the mold apparatus 14b and disposed. A robot is preferably used to carry the insert molded body 26 into the mold apparatus 14b.

  (S22) The spaces for the first layer 21 and the third layer 23 formed in the cavities 7k and 7l by the insert molding 26 are the sprues 28 and 29 and the gates 8i and 8j from the first injection device and the second injection device. Are simultaneously injected and filled with a molten resin supplied via By this insert molding, the insert molded body 26 is surrounded by the first layer 21 and the third layer 23.

  (S23) In the insert molding step, the surface of the insert molded body 26 is melted with a molten resin so that irregularities and gate marks on the surface of the insert molded body 26 do not appear on the lens surface.

  As is clear from the above detailed description, in the manufacturing process of the multilayer molded lens 20b in the third embodiment, an insert molded body that integrally constitutes each other layer except the first layer and the Nth layer is used as a mold apparatus. A step of carrying in and disposing; and an insert molding step of simultaneously molding the first layer and the Nth layer exposing the gate traces on the outer surface of the lens and surrounding the insert molded body with the first layer and the Nth layer; And a melting step of melting the surface of the insert molded body so that irregularities and gate traces on the surface of the insert molded body do not appear on the lens surface in the insert molding step.

  Therefore, irregular changes in the viscosity of the molten resin such as cold slug do not occur in the important parts of the first and third layers forming the lens surface, so that the appearance quality of the lens is improved and the optical characteristics of the lens are improved. . In addition, since the irregularities and gate marks on the surface of the insert molded body 26 are melted and disappeared, the optical characteristics are not affected. Furthermore, since the molding cycle of the insert molded body 26 can be made relatively short, productivity can be improved.

[Modification]
In a headlamp of a vehicle or the like to which the multilayer molded lenses 20 and 20a are applied, a fine uneven shape is formed on the lens surface in order to improve color blurring near a light / dark boundary line in a predetermined light distribution pattern or to provide a blurring effect. May be required. In this modification, fine irregularities 19 are formed on the cavity surfaces 6a to 6j, 5f, and 5h to 5j for the first layer or the third layer (Nth layer) based on the first embodiment to the third embodiment. This is a modification. At the time of molding the first layer or the Nth layer, the molten resin transfers the fine irregularities 19 to form the fine irregularities 19a on the lens surface, which is the important part surface of the first layer or the Nth layer.

  As shown in FIGS. 11 and 12, the fine unevenness 19 is configured by an infinite number of unevenness of several micrometers to several millimeters, for example, having a shape similar to a half-wave rectified wave shape or a sine wave shape in cross-sectional view. It is. The fine irregularities 19 that are generally referred to as textures are provided on the entire surface of one of the first layer cavity surfaces 6a to 6j and the fifth layer cavity surface 5f or a part thereof. The fine irregularities 19 are provided on the entire surface of one of the first layer cavity surfaces 6g to 6j and the third layer (Nth layer) cavity surfaces 5f and 5h to 5j or a part thereof. In the first embodiment and the second embodiment, the fine irregularities 19 are not provided on the first-layer cavity surfaces 6a to 6h which are required to be six or two, but only one fifth layer or third layer. Preferably, it is provided on the cavity surfaces 5f and 5h for use. The reason is as follows. In order to manufacture one cavity surface having the fine irregularities 19, a processing cost of several million yen or more is required. Therefore, in the case where the fine unevenness 19 is applied to the first layer cavity surfaces 6a to 6h, which is required for only one fifth layer or third layer cavity surface 5f, 5h. , Cost 6 times or twice as much as several million yen.

  The gates 8a, 8f, 8g, and 8h for the first layer and the Nth layer are set to have a relatively large cross-sectional area, so that the molding pressure of the molten resin can be uniformly transmitted to the molding cavity with low pressure loss. Can do. Therefore, the fine unevenness 19 is accurately transferred and molded to the first layer or the Nth layer, and the fine unevenness shape 19a having a shape as close as possible to the fine unevenness 19 can be formed on the lens surface. This effect is the same even when the fine unevenness 19 is engraved on any cavity surface of the first layer or the Nth layer.

  In addition, this invention includes what can be implemented in the aspect which added various change, correction, improvement, etc. based on the knowledge of those skilled in the art. Further, it goes without saying that any of the embodiments to which the above-mentioned changes are added is included in the scope of the present invention without departing from the gist of the present invention.

  For example, in the first embodiment, the multilayer molded lens 20 has been described as having five layers, but the number of layers is not limited as long as the number of layers is an integer (N) of 3 or more. At that time, the number of molding cavities is N, which is the same as the number of layers.

  Further, in the first embodiment, it has been described that all the layers are formed by lamination molding. However, one or a plurality of layers other than the first layer and the Nth layer are replaced by lamination molding, and the second layer is formed. You may make it form by the insert molding demonstrated in embodiment. In that case, the molding cavity for the layer formed by insert molding becomes unnecessary. The insert molded body is placed on the surface of the intermediate molded body in the molding cavity for the next layer of the layer formed by insert molding after the second cavity block is opened and rotated.

  In the first embodiment, the example in which the surface curvature of the first layer of the multilayer molded lens 20 is smaller than the surface curvature of the fifth layer has been described. However, the surface curvature of the first layer is larger than the surface curvature of the fifth layer. You may comprise. In that case, the cavity surface of the first template may protrude from the mold alignment surface.

  In the first embodiment, the configuration has been described in which the end surfaces of the second layer 22, the third layer 23, and the fourth layer 24 that are the inner layers of the multilayer molded lens 20 are in contact with the inner layer side of the first layer 21. On the other hand, the inner layer can also be configured such that the end surface of the inner layer is in contact with the inner layer surface of the Nth layer.

  Moreover, although the example which arrange | positions a shaping | molding cavity on the periphery was shown in 1st embodiment, you may arrange | position a shaping | molding cavity on a straight line. Further, the second cavity block may be replaced manually or automatically in one molding cavity instead of arranging a plurality of molding cavities in advance.

  In the first embodiment, the inner layer gates 8b to 8d are shown in the central portion of each inner layer. However, the gate position of the inner layer is covered by lamination molding of the inner layer and subsequent layers. As long as it is in a position where it can be seen, it does not matter. In particular, when the inner layer is configured such that the end surface of the inner layer is in contact with the inner layer surface of the Nth layer, a gate can be disposed on the end surface of the inner layer.

  In the first to third embodiments, the gate traces 9a and 9f to 9j are provided on the end surface of the flange portion 16 as the outer peripheral end surface of the multilayer molded lenses 20 and 20a. However, the gate traces of the first layer and the Nth layer are provided on the outer surface of the lens, which is both surfaces or one of the surfaces excluding the end surface of the collar portion provided outside the important portion (optical surface) of the multilayer molded lens. You may do it. Further, the gate traces of the first layer and the Nth layer may be provided on the outer surface of the lens as the end face of the important part of the multilayer molded lens having no collar.

  In addition, in the first embodiment and the second embodiment, the heel part 16 is shown as an annular shape like a heel of a hat, but a part of the heel part 16 projects over one or more like a heel of a baseball cap. There may be.

  In the first embodiment, an example in which the hot runner 10 is in contact with the first layer 21 gate 8a and the fifth layer 25 gate 8f is shown. In the second embodiment, the first layer 21 gate 8g and the fifth layer 25 gate 8f The example in which the hot runner 10 is in contact with the gate 8h for the three layers 23 is shown. However, a side gate or the like may be used instead of the hot runner.

  In the first embodiment, the cooling cavity has been described as an example in which the cooling cavity 7e is provided for the intermediate molded body including the first to fourth layers. However, three or more cooling cavities can be provided for any one or more of the N molding cavities. In particular, when a cooling cavity is provided for the Nth layer, sink marks of the Nth layer, which is the outer layer, greatly affect the optical characteristics, so that the cooling cavity becomes more effective. Note that the cooling cavity is not essential, and the cavity block may be configured by only the molding cavity without providing the cooling cavity.

5a to 5j Cavity surface 6a to 6j Cavity surface 7a to 7d, 7f to 7l Molding cavity 7e Cooling cavity 8a to 8d, 8f to 8j Gate 9a to 9d, 9f to 9j Gate mark 14, 14a, 14b Mold device 17 Critical part 18 Mold matching surface 19 Fine unevenness 19a Fine uneven shape 20, 20a, 20b Multilayer molded lens 21 First layer 22 Second layer 23 Third layer (Nth layer)
24 4th layer 25 5th layer (Nth layer)

Claims (8)

A multilayer molded lens having three or more layers (N layers),
The gate mark of the gate formed with the first layer and the Nth layer is exposed on the lens outer surface,
A multilayer molded lens in which the gate marks of the gates formed from the second layer to the (N-1) th layer are not exposed on the lens outer surface and the lens surface.   The multilayer molded lens according to claim 1, wherein the gate marks of the first layer and the Nth layer are adjacent to each other at the same position on the outer peripheral end surface of the lens. An intermediate molded body as a first layer molded with a molding cavity having a minimum volume among a plurality of molding cavities having different volumes is transferred to a molding cavity having a larger volume and the second layer is laminated or insert molded. The intermediate molded body is subsequently transferred to each layer molding cavity up to the N-th layer and laminated molding or insert molding to produce a multilayer molded lens having three or more layers (N layers),
A layer forming step of forming a first layer and an Nth layer by exposing a gate mark on the outer surface of the lens;
Lamination molding process or insert molding process for forming each of the layers other than the first layer and the Nth layer;
A melting step for melting the gate marks generated in the laminate molding step or the insert molding step so as not to appear on the lens surface in the molding after the next layer; and
A method for producing a multilayer molded lens comprising:   4. The method of manufacturing a multilayer molded lens according to claim 3, wherein the gate mark of each of the first layer and the Nth layer is provided adjacent to the same portion of the lens outer peripheral end surface.   5. The method of manufacturing a multilayer molded lens according to claim 3, further comprising a step of cooling the intermediate molded body with a cooling cavity provided adjacent to one or a plurality of the molding cavities in a transfer direction of the intermediate molded body. .   6. The method of manufacturing a multilayer molded lens according to claim 5, wherein the cooling cavity does not have a gate which is an injection port for molten resin. A method for producing a multilayer molded lens having three or more layers (N layers),
A step of carrying in and disposing an insert molded body integrally forming each of the layers other than the first layer and the Nth layer into a mold apparatus;
An insert molding step of simultaneously molding a first layer and an Nth layer that expose a gate mark on the outer surface of the lens and surrounding the insert molded body with the first layer and the Nth layer;
A melting step of melting the surface of the insert molded body so that irregularities and gate traces on the surface of the insert molded body do not appear on the lens surface in the insert molding step;
A method for producing a multilayer molded lens comprising:   When molding the first layer or the Nth layer, the fine irregularities formed on the cavity surface are transferred to form a fine irregularity shape on the lens surface which is the surface of the first layer or the Nth layer. The manufacturing method of the multilayer molded lens as described in any one of Claims 3 thru | or 7.

Images