JPWO2012132597A1 - Mold apparatus for multilayer molding and multilayer molded product - Google Patents

Abstract

Provided are a mold apparatus for multilayer molding and a multilayer molded article that can facilitate mold design and improve optical characteristics in lens molding. An intermediate molded product obtained by injecting molten resin into each of N mold cavities 6 formed by matching the molds of the first cavity block 2 and the second cavity block 3 and having different volumes from each other has a volume. When forming the N-layer multilayer molded article 15 by sequentially transferring and injecting it to the larger mold cavity 6, each of the mold matching state from the first layer to the mold matching state of the (N−1) -th layer The gates 7a to 7g in the mold-matching state are provided at positions where the gate traces of the gates do not appear on the outer surface of the multilayer molded product 15, and are for forming the Nth layer that maximizes the volume of the mold cavity. The gate for supplying the molten resin to the mold cavity in the mold-matching state is provided at a position corresponding to the outer surface of the multilayer molded product.

Description

  The present invention relates to a mold apparatus for performing multilayer molding and a multilayer molded article molded by the mold apparatus.

  Projector lenses such as LED lighting whose demand is increasing in recent years are thick lenses of 12 mm or more due to their light condensing characteristics. When such a thick plastic lens is molded as a conventional molding method, a long cooling time is required to reduce the influence on the optical characteristics of sink marks generated in the maximum thickness portion. As a means for solving this problem and shortening the molding time, a multilayer molding technique has been proposed.

  In Patent Document 1, a plurality of molds that are sequentially increased in thickness from any one side with respect to the thickness direction of the resin thick lens, and finally reach a specified thickness are disclosed. A multilayer technology is disclosed in which a resin is injected a number of times for each mold while forming and exchanging the mold on one side.

  Further, Patent Document 2 discloses a multilayering technique in which a convex lens having a thickness approximately equal to that of the insert is formed by performing secondary molding using a convex lens having a thickness of about ½ of the thickness of the finally obtained convex lens as an insert. It is disclosed.

JP 2001-191365 A Japanese Patent Publication No. 3-31124

  In the multilayer technology of Patent Document 1 and Patent Document 2 described above, injection filling for molding each layer is performed not from the optical surface of the lens but from the gate provided on the outer peripheral end surface of the lens. However, since the thickness dimension of the outer peripheral end face is extremely small due to the cross-sectional shape characteristics of the thick convex lens, it is difficult to provide all the gates of each layer in the multilayer molded product on the outer peripheral end face. Also, if multiple layers of gates are provided on the outer peripheral end face of the convex lens, the sectional area of the gates of each layer will be extremely small, so residual stress will concentrate on the molten resin at that location, leading to deterioration of optical properties. become. These problems become significant in the case of multi-layer molding of four or more layers that can sufficiently obtain the effect of multi-layering.

  The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a mold apparatus for multilayer molding that can facilitate mold design and improve optical characteristics in lens molding. To do.

  In the present invention, one or a plurality of first cavity blocks forming one side of a mold cavity with the same shape and size, and the other side of the mold cavity is a volume (volume). And a second cavity block that is formed of protrusions or recesses having different heights (depths) and that is paired with the first cavity block, one or a plurality of first templates that fix the first cavity block, and The second cavity block is fixed and the second mold plate is paired with the first mold plate, and the first cavity block and the second cavity block are all formed by mold matching and have a mutual volume. An intermediate molded product formed by injecting molten resin into each of a plurality of different (N) mold cavities is sequentially transferred to a mold cavity having a larger volume of the mold cavities and shot. In a multi-layer molding apparatus for molding a N-layer multi-layer molded product by repeating the above, the volume of the mold cavity is changed from the mold matching state for the first layer molding where the volume of the mold cavity is minimized. Each gate for supplying molten resin to each mold cavity in each mold matching state up to the mold matching state for the (N-1) th layer, which is one step before forming the Nth layer where the maximum is, Molten resin is applied to the mold cavity in the mold-matched state for molding the Nth layer, where the gate trace of the gate is provided at a position where it does not appear on the outer surface of the multilayer molded product, and the volume of the mold cavity is maximized. The gate to be supplied is provided at a position corresponding to the outer surface of the multilayer molded article.

  According to this configuration, since the gate trace of the gate for molding each layer is provided at a position where it does not appear on the outer surface of the multilayer molded product, the area where the gate can be installed becomes relatively wide. Therefore, the mold can be easily designed, and the gate can be provided at a position and in an optimum state for molding of each layer. In addition, there is an excellent effect that the degree of freedom in designing the molded product is improved and the design is facilitated. Moreover, since the gate traces of the respective gates from the first layer to the (N-1) th layer are covered by the subsequent layer molding or the Nth layer molding, the respective gates from the first layer to the (N-1) th layer are covered. The gate trace and the interface of the intermediate molded product are melted, and the minute unevenness and residual stress disappear. Therefore, when the multilayer molded article is an optical product such as a lens, there is an excellent effect that a multilayer molded article having excellent optical characteristics can be manufactured.

  According to the present invention, the depth dimension of the concave portion that forms one side of each mold cavity and has the same shape and the same dimension is set to the maximum depth of the concave portions that form the other side of each mold cavity. It is characterized by being configured to be smaller than the size.

  According to this structure, it becomes possible to reduce the processing cost of the recessed part which forms a metal mold cavity. In particular, when the multilayer molded product is an optical lens, it is necessary to make the concave portion an aspherical mirror surface, and the processing cost is high.

  The present invention is characterized in that the gate provided at a position where a gate mark does not appear on the outer surface of the multilayer molded article is a pin gate or a hot runner.

  According to this configuration, since the gate trace is relatively small, coating with a subsequent layer can be easily performed, and a multilayer molded product with excellent optical characteristics can be obtained, and the intermediate molded product can be easily separated at the gate and multilayer molded. Improve process efficiency.

  In the present invention, the difference between the maximum height or maximum depth of the protrusion or recess for forming the Nth layer and the maximum height or depth of the protrusion or recess for forming the (N-1) th layer is It is characterized by being configured to be smaller than the same difference between any layers in the younger layer order.

  According to this configuration, since the mold transferability of the mold cavity surface is improved, there is an excellent effect that a high-quality multilayer molded product can be obtained.

  The present invention is a multilayer molded product molded using the above-mentioned mold apparatus for multilayer molding, wherein the gate mark of the gate formed with the Nth layer is exposed on the outer surface thereof, and the gate formed with other layers is formed. The scar is not exposed.

  According to this configuration, the multilayer molded product of the present invention has an excellent effect of being excellent in appearance since the gate trace is exposed only in one place. Further, the gate trace of the inner layer gate that is indispensable for such a configuration melts and disappears at the interface, and only the gate trace of the gate formed with the Nth layer is exposed to the outer surface. There is an excellent effect that the characteristics are not deteriorated.

  The present invention is a multilayer molded product molded using the mold apparatus for multilayer molding, wherein the outer peripheral end of the multilayer molded product is formed in one or two layers, and the outer peripheral end of the multilayer molded product The portion except for is formed in the N layer.

  According to this configuration, the multilayer molded article of the present invention is formed with one or two outer peripheral ends even though the portion other than the outer peripheral end is a multilayer of three or more layers. That is, since the portion other than the outer peripheral end portion is a multilayer, the original function is exhibited, and the outer peripheral end portion that requires only the function as an attachment member is formed in the minimum necessary shape while maintaining the formability. Can do. Therefore, the multilayer molded article of the present invention has an excellent effect that the functional, characteristic and appearance are good.

  The present invention is a multilayer molded article molded using the multilayer molding die apparatus, wherein one surface of the multilayer molded article comprises a first layer of multilayer molding and has a small curvature or a planar shape. The other surface of the multilayer molded article is composed of an Nth layer of multilayer molding and has a curvature larger than that of the one surface.

  According to this configuration, the mold apparatus for molding the multilayer molded product of the present invention can reduce the processing cost by reducing the processing area of the concave portion on the side having the same shape and the same dimensions. Therefore, the mold apparatus can be manufactured at a low cost, and the multi-layer molded product of the present invention has an excellent effect that the price is low.

  The present invention is characterized in that the multilayer molded article is an optical lens.

  According to this configuration, there is an excellent effect that a high-quality optical lens can be obtained.

FIG. 1 is a side view of a partial cross section showing the configuration of an embodiment of the mold apparatus of the present invention. FIG. 2 is a front view showing a state of the first cavity block in which the mold cavities are opened after injection when there are eight mold cavities (eight layers). FIG. 3A is an enlarged front view showing details of the mold cavity (eighth layer) portion of FIG. 2. 3B is a cross-sectional view taken along the line IIIA-IIIA of FIG. 3A showing the mold cavity (eighth layer) of FIG. 4A is a front view of a mold cavity showing a first variation of the gate in FIG. 4B is a cross-sectional view of a mold cavity showing a first variation of the gate in FIG. FIG. 5 is a sectional view of a mold cavity showing a second modification of the gate in FIG. FIG. 6 is a sectional view of a mold cavity showing a third modification of the gate in FIG. FIG. 7 is a perspective view of a multilayer molded product molded by the mold apparatus shown in FIGS. FIG. 8 is a side view of a multilayer molded product having two outer peripheral end portions. FIG. 9 is a perspective view with a partial cross section of a multilayer molded product molded by a mold apparatus having a gate according to a fourth modified embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, parts corresponding to each other in all the drawings in this specification are denoted by the same reference numerals, and description of the overlapping parts will be omitted as appropriate.

  As shown in FIG. 1, the mold apparatus 1 of the present embodiment includes a pair of a first cavity block 2 and a second cavity block 3 that form a mold cavity 6 by matching with each other, and a first cavity block 2. Is composed of a pair of a first mold plate 4 for fixing the second mold plate 5 and a second mold plate 5 for fixing the second cavity block 3. As shown in FIG. 1, it is effective to provide a plurality of mold cavities 6 in the pair of first cavity block 2 and second cavity block 3 in terms of improving economy and workability. However, one mold cavity may be provided in the pair of first cavity block and second cavity block. At this time, the first mold plate and the second mold plate fix the same number of first cavity blocks and second cavity blocks to the predetermined positions as the number of layers (N) of the multilayer molded product to be obtained. Further, one or a plurality of pairs of a first cavity block and a second cavity block having one or a plurality of mold cavities may be fixed to one or a plurality of pairs of a first mold plate and a second mold plate, respectively. Furthermore, when there are a plurality of pairs of the first mold plate and the second mold plate, all the pairs of the first mold plate and the second mold plate are attached to the same mold clamping device, or the first mold plate and the second mold plate Either configuration, in which some pairs are distributed and mounted on other mold clamping devices, can be implemented. Thus, between the number of mold cavities, the number of first and second cavity block pairs, the number of first and second mold plate pairs, and the number of clamping devices. It goes without saying that various combinations can be implemented as long as the mold cavities are arranged with predetermined requirements as described later, and these are included in the scope of the present invention.

  As shown in FIG. 1, the mold cavity 6 includes a first cavity block 2 and a second cavity block 3, one side formed on the first cavity block 2 and the other side formed on the second cavity block 3. It is formed by integrating with mold matching. The number of mold cavities 6 is the same as the number of layers (N) of the multilayer molded product molded by the mold apparatus 1. All the concave portions forming one side of the mold cavity 6 in the first cavity block 2 have the same shape and the same dimensions. The protrusion 12 that forms the other side of the mold cavity 6 in the second cavity block 3 has a height dimension smaller than the depth dimension of the recess that forms one side of the mold cavity 6, and the mold alignment of the second cavity block 3 It protrudes from the surface and has an outer peripheral shape similar to the outer peripheral shape of the recess. As shown in FIGS. 2 and 3 (a), which is an example of N = 8, the height dimension and the outer peripheral diameter of the protrusion 12 protrude from the protrusion 12a corresponding to the mold cavity 6h from the mold cavity 6a. Both are set so as to decrease sequentially toward the portion 12h (indicated by a two-dot chain line and parentheses for convenience). However, the protrusion 12 may protrude to a negative height to form a recess. The shape of the protrusion at that time is represented not by volume and height but by volume and depth (the same applies hereinafter). The outer peripheral ends of the mold cavities 6 a to 6 h are opposed to the mold cavity surface of the second cavity block 3. Note that the height of the protruding portion 12h is zero in this embodiment. That is, the surface of the multilayer molded product molded by the mold cavity 6h is a flat surface. As shown in FIG. 2, the mold cavities 6a to 6h formed in this way are arranged at equal intervals on the circumference. The volumes of the mold cavities 6a to 6h are sequentially increased from the mold cavity 6a toward the mold cavity 6h. The mold cavities may be arranged not on the circumference but on a straight line.

  In the mold cavity 6a in which the volume of the protruding portion 12a is the largest and the volume of the mold cavity is the smallest, an intermediate molded product as the first layer is molded. The intermediate molded product is transferred from the mold cavity 6a to the adjacent mold cavity 6b where the volume of the mold cavity is larger by means such as rotating the first mold plate 4 when the mold is opened. In the mold cavity 6b, the substantial mold cavity 6b is formed by the surface on the second cavity block side of the intermediate molded product of the first layer, and the second layer is molded. In this way, the intermediate molded product molded from the first layer to the seventh layer corresponding to the mold cavity 6g from the mold cavity 6a is sequentially transferred to a mold cavity having a larger mold cavity volume. As shown in FIG. 3B, in the mold cavity 6h in which the volume of the projecting portion 12h is the smallest and the volume of the mold cavity is the largest, the eighth layer as the final layer in the case of N = 8 is molded, and the multilayer molding is performed. Products 15 and 16 are completed. Thereafter, the multilayer molded products 15 and 16 are released from the mold cavity 6h and taken out. In addition, although the convex lens was illustrated as the multilayer molded products 15 and 16, the multilayer molded product may be a light guide plate which is an optical product, or may be a non-optical product.

  By the way, the surface 19 as the Nth layer of the multilayer molded product 16 is formed by transfer molding with the protruding portion 12 when it is assumed that the concave portion deeper than the concave portion depth of the first cavity block 2 in the mold of FIG. The When the multilayer molded product 16 is an optical product, the transfer state of the surface 19 is an important factor that affects the characteristics of the multilayer molded product 16. A good transfer state appears when the surface shape of the protrusion 12 is faithfully transferred. To do so, it is necessary to mitigate the cooling effect when the Nth layer is formed. For this reason, the temperature of the protrusion 12 for forming the Nth layer is set higher than the temperature of the protrusions for forming other layers. Therefore, in order to unify the molding time of each layer from the first layer to the Nth layer, it is preferable to make the difference between the heights or depths of the protrusions 12 forming each layer uniform between the layers. In order to make the maximum thickness dimension of the N layer the smallest among the maximum thickness dimensions of the other layers, the maximum height or the maximum depth of the protrusion 12 (recess) for forming the Nth layer, ) A difference between the maximum height or the maximum depth of the layer-forming projecting portion 12 (concave portion) is configured to be smaller than the same difference between any layers in the order of younger layers.

  As shown in FIGS. 2 and 3, the gates 7 a to 7 g are provided at the end of the counter electrode with respect to the communicating portions of the resin passages 11 a to 11 g that protrude and communicate with the outer periphery of the mold cavities 6 a to 6 g. As shown in FIG. 1, runners 8 formed by drilling through the second cavity block 3 and the second template 5 are connected to the gates 7 and 7 a to 7 g. Each runner 8 can be cut from the gates 7 and 7 a to 7 g when the intermediate molded product is released from the second cavity block 3. The runner 9 is provided in the second template 5 so as to communicate with the runner 8. The runner 9 is preferably a hot runner or a cold runner. However, the runner 9 and the runner 8 may be taken out from a gap formed by dividing the second template 5 at the runner 9 portion. The sprue 10 is provided by being drilled in the second template 5 so as to communicate with the runner 9, and a nozzle of an injection device (not shown) is brought into contact with the opening end of the sprue 10 to inject molten resin. The gates 7a to 7g are preferably pin gates in that the gate marks are made as small as possible to facilitate separation from the intermediate molded product. Moreover, the structure which uses the gates 7a-7g as the hot tip of a hot runner is effective in that the separation of the intermediate molded product is further facilitated. The gates 7a to 7g are provided at positions that become the mold cavity surface of the Nth layer, but instead, the resin passages 11a to 11g are extended outwardly to the surface that becomes the outer peripheral end surface of the multilayer molded product. You may comprise so that it may provide. In this case, the gate of the 1st layer thru | or the (N-1) layer is provided in one surface of the outer peripheral end surface used as the two layers of the multilayer molded product, and the outer peripheral end surface used as the two layers of the multilayer molded product. The gate of the Nth layer is provided on the other surface.

  As shown in FIGS. 2 and 3, the resin passages 11 a to 11 g are connected to the outer peripheral end portions of the projecting portions 12 a to 12 g (concave portions) on the mold matching surface of the second cavity block 3 with the first cavity block 2. Based on the rod-shaped protrusions 13 (shown in parentheses for convenience) provided at the time of forming each layer. The resin passages 11a to 11g have sufficient cross-sectional area to reduce the stress based on the injection pressure remaining in the vicinity of the molten resin inlet to the mold cavities 6a to 6g, thereby improving the optical characteristics of the multilayer molded product. Has the effect of Further, the resin passages 11a to 11g can be adjusted in gate balance by changing their cross-sectional areas for the respective mold cavities 6a to 6g.

  As shown in FIG. 4, the gate 7i is a first modification of the gates 7a to 7g. The gate 7i is directly provided in a portion of the mold cavities 6a to 6g facing the second cavity block 3. That is, the gate 7i is provided on the surface of the mold cavity 6h for molding the eighth layer (Nth layer), and the gate trace is the latter and the interface is formed by molding the eighth layer as the Nth layer. Is melted, so that minute unevenness and residual stress disappear, and a multilayer molded article 15 having excellent optical characteristics can be manufactured. The gate 7i is preferably a pin gate. Since this configuration does not require a resin passage, it is very simple and a mold apparatus for multilayer molding can be easily configured.

  As shown in FIGS. 3 and 4, the gate 7 h is provided at a position corresponding to the outer peripheral end surface of the multilayer molded product 15 formed by the mold cavity 6 h of the eighth layer (Nth layer). The gate 7h is preferably a side gate having a relatively large cross-sectional area in order to reduce residual stress remaining on the outer peripheral end face of the multilayer molded product. On the outer peripheral end face of the multilayer molded article 15, as shown in FIG. 7, a gate mark 14 formed by the runner being cut and separated at the gate 7h portion appears. The molded product 15 molded by the mold apparatus shown in FIG. 4 is a molded part of the first layer, which is the molded part of the A layer 20 where the gate trace is not exposed, and the molded part of the eighth layer (Nth layer). It has an outer peripheral end portion composed of two layers with the B layer 21 from which the gate mark 14 is exposed. Although not shown, the gate 7h is provided not at a position corresponding to the outer peripheral end face of the multilayer molded product 15 but at a position corresponding to or near the outer peripheral end formed by molding the eighth layer (Nth layer). You may do it. Further, the mold apparatus shown in FIG. 4 is configured so as not to form the A layer 20 by molding the first layer, and the outer peripheral end of the molded product 15 is formed by molding the eighth layer (Nth layer). You may comprise only.

  As shown in FIG. 3, the mold cavity 6h for the eighth layer (Nth layer) includes the above-described intermediate molded products as the first to seventh layers, the resin passages 11a to 11g, and the gates 7a to 7a. 7g (gate 7i) is essentially one side. The molding of the eighth layer (Nth layer) into the mold cavity 6h covers the intermediate molded product as the first to seventh layers, the resin passages 11a to 11g, and the gates 7a to 7g (gate 7i). This is the final step of forming a multilayer molded product. Therefore, the traces of the gates 7a to 7g do not appear on the outer surface of the multilayer molded product, and only the gate trace 14 which is the trace of the gate 7h remains on the outer peripheral end face as shown in FIG. Further, the molded product 15 molded by the mold apparatus shown in FIG. 3 is a molded portion of the first layer, which is a molded portion of the A layer 20 where the gate trace is not exposed, and an eighth layer (Nth layer). It has an outer peripheral end portion composed of two layers with the B layer 21 from which the gate mark 14 is exposed. Although not shown, the gate 7h is provided not at a position corresponding to the outer peripheral end face of the multilayer molded product 15 but at a position corresponding to or near the outer peripheral end formed by molding the eighth layer (Nth layer). You may do it. Further, the mold apparatus shown in FIG. 3 is configured so as not to form the A layer 20 by molding the first layer, and the outer peripheral end of the molded product 15 is formed by molding the eighth layer (Nth layer). You may comprise only.

  In the step of the eighth layer (Nth layer) covering the intermediate molded product as the first layer to the seventh layer, the resin passages 11a to 11g, and the gates 7a to 7g (gate 7i), the flowing molten resin is the first Since the intermediate molded product as the layer to the seventh layer, the resin passages 11a to 11g, and the surfaces of the gates 7a to 7g (gate 7i) and the interfaces between them are melted, minute unevenness and residual stress are eliminated. A multilayer molded article having excellent optical characteristics can be produced. The gates 7a to 7g (gate 7i) can be set at any position corresponding to the optical surface that is the surface on which the mold cavity 6h for forming the eighth layer (Nth layer) is formed. This increases the degree of freedom in product design.

  FIG. 5 shows a second modification of the gates 7a to 7g. FIG. 5 shows a molded state of the third layer in the mold apparatus of FIG. The gate 7j is located at the tip of the runner 8 formed by drilling the protrusion 12 that forms each layer from the first layer to the (N-1) th layer. The surface facing the second cavity block 3 of the intermediate molded product formed by the projecting portion 12 becomes a mold cavity surface for forming the fourth layer as a later generation. Therefore, the gate 7j is provided on the mold cavity surface for subsequent layer molding of each layer. The gate 7j can be provided in one or a plurality of arbitrary mold cavities. Since the interface of the gate trace of the gate 7j generated by the molding of each layer is melted by the subsequent layer molding, minute unevenness and residual stress disappear, and the multilayer molded article 15 having excellent optical characteristics can be manufactured. . Further, as shown in FIG. 7, the molded product 15 molded by the mold apparatus having the configuration shown in FIG. 5 is the first layer molding portion A layer 20 where the gate trace is not exposed, and the eighth layer (Nth layer). The outer peripheral end portion is composed of two layers, namely, a B layer 21 where the gate mark 14 is exposed. Although not shown, the gate for forming the eighth layer (Nth layer) is a position corresponding to the outer peripheral end face of the multilayer molded product 15 or the outer peripheral end formed by molding the eighth layer (Nth layer). Or it can provide in the position equivalent to the vicinity. Further, the mold apparatus shown in FIG. 5 is configured so that the A layer 20 is not formed by molding the first layer, and the outer peripheral end of the molded product 15 is formed by molding the eighth layer (Nth layer). You may comprise only.

  FIG. 6 shows a third modification of the gates 7a to 7g. FIG. 6 shows a molded state of the seventh layer ((N-1) layer) in the mold apparatus of FIG. The gate 7k is provided on the mold cavity surface for the seventh layer molding corresponding to each layer molding from the first layer to the sixth layer. The gate 71 is located at the tip of a runner 8 formed by drilling in the second cavity block 3 for molding the seventh layer, and is provided on the mold cavity surface for molding the eighth layer (Nth layer). The gate marks of the gate 7k generated in each molding from the first layer to the sixth layer are melted at the interface by the subsequent molding of the seventh layer, so that minute unevenness and residual stress disappear, and the optical characteristics An excellent multilayer molded article can be produced. In the multilayer molded product molded by the mold apparatus shown in FIG. 6, the molded portion in the first layer is the A layer, the molded portion in the seventh layer is the C layer, and an eighth layer (Nth layer) not shown. ) Has a three-layer outer peripheral end portion which is a B layer. At this time, the gate for forming the eighth layer is provided at a position corresponding to the outer peripheral end surface of the multilayer molded product, or an outer peripheral end formed by molding the eighth layer (Nth layer) or a position corresponding to the vicinity thereof. Can do. Note that the mold apparatus shown in FIG. 6 is configured so that the outer peripheral end of the multilayer molded product is not formed by molding the first layer and the seventh layer, and the outer peripheral end of the multilayer molded product is the eighth layer (Nth layer). ) May be formed of only one layer.

  As described above, in the embodiment according to FIGS. 2 to 6, the depth dimension of the concave portion that forms one side of each mold cavity 6 and has the same shape and the same dimension is included in each protrusion 12. Is greater than the maximum height dimension. On the other hand, the depth dimension of the concave portion that forms one side of each mold cavity 6 and has the same shape and the same dimension is set to the maximum depth of the concave portions when the protruding portion 12 is concave. It can also be configured smaller than the dimensions. By comprising in this way, it becomes possible to reduce the processing cost of a recessed part. In particular, when the molded product is an optical lens, it is necessary to make the concave portion an aspherical mirror surface, and the processing cost is high.

  The multilayer molded product 16 shown in FIG. 8 is an optical lens molded by the multilayer molding die apparatus having such a configuration. The multilayer molded product 16 includes an aspherical or planar surface 18 having a small curvature that is transferred and molded by one of the concave portions having the same shape in the mold cavity, and a concave portion when the protruding portion 12 is concave. The surface 19 is formed of an aspherical surface 19 having a curvature larger than the curvature of the surface 18 which is transferred and molded in the concave portion having the maximum depth. The surface 18 is the first layer of the multilayer molded product, and the surface 19 is the Nth layer of the multilayer molded product. In addition, the molded product 16 has an outer peripheral end portion composed of two layers in which a molded portion in the first layer is an A layer 20 and a molded portion in the eighth layer (Nth layer) which is the final layer is a B layer 21. Have. Thus, according to the multilayer molding die apparatus having the configuration described in the previous section, both surfaces of the optical lens having different curvatures can be formed easily and at low cost.

  FIG. 9 shows a multilayer molded article 17 as another example of the multilayer molded article 16 shown in FIG. 8, and includes a fourth modification of the gate. The multilayer molded product 17 is molded by a mold apparatus different from the mold apparatus shown in FIG. That is, the gates 7a to 7g for supplying the molten resin to the mold cavities from the first layer to the seventh layer in FIG. 3 are provided at the end portions of the resin passages 11a to 11g toward the eighth layer mold cavity. It has been. On the other hand, in the mold apparatus for the multilayer molded product 17, the gate is provided at a portion of the resin passages 28 to 31 that extends to the outer peripheral end surface of the multilayer molded product 17. In the mold apparatus shown in FIG. 3, the mold layers are laminated in the order from the convex surface to the plane, whereas in the mold apparatus of the multilayer molded product 17, the layers are laminated in the order from the plane to the convex surface. The multilayer molded product 17 molded in this way has a gate trace 22 of a gate formed with the A layer 20 as the first layer not provided with a resin passage on one of the outer peripheral end surfaces formed into two layers. On the other of the outer peripheral end surfaces of the two layers, the gate trace 23 of the gate formed by molding the second layer 32 through the resin passage 28 and the gate trace 24 of the gate formed by molding the third layer 33 through the resin passage 29. The gate mark 25 of the gate formed by molding the fourth layer 34 through the resin passage 30, the gate mark 26 of the gate formed by forming the fifth layer 35 through the resin passage 31, the sixth layer 36 and the seventh layer. 37 has a gate mark (not shown), and a gate mark 27 of a gate formed with an eighth layer 38 (B layer 21) having no resin passage. As described above, the second layer to the seventh layer ((N-1) layer) forming each intermediate molded product in the first layer to the sixth layer ((N-2) layer) molding substantially Each mold cavity is provided with a resin passage that communicates radially from its outer periphery to the gate on the surface of the A layer 20 (first layer). Although the lamination of each layer from the third layer to the seventh layer is shown to cover the entire surface of the previous layer, the mold cavity may be configured to partially cover a part of the previous layer. In that case, the resin passage is provided on the surface of the intermediate molded product formed of a plurality of layers. The gate is preferably a side gate that is less affected by heat generation at the gate portion.

  As described above, all of the multilayer molded products shown in FIGS. 7, 8, and 9 have the flanges as the outer peripheral ends thereof from the first layer molded portion and the Nth layer molded portion as intermediate molded products. Are formed in one layer composed of a two-layer or N-th layer molding portion. In this case, the main part which is a part except the collar part in a multilayer molded product is an N layer. In the conventional mold apparatus, in order to form the main part of the N layer, a collar portion having a thickness corresponding to the thickness of the N layer is required. Therefore, since the outer peripheral end of the multilayer molded product of the present invention has one or two layers even if N is 3 or more, the excellent effect of the present invention is exhibited when N is 3 or more. .

  As is clear from the above detailed description, according to the multilayer molding die 1 of this embodiment, the mold cavity can be moved from the mold alignment state for the first layer molding where the volume of the mold cavity is minimized. Each of the molten resins is supplied to the respective mold cavities 6a to 6g in the respective mold-matching states up to the mold-matching state for the seventh layer, which is just before the eighth layer (N = 8) molding with the largest volume. Since the gate is provided at a position where the gate trace of the gate does not appear on the outer surface of the multilayer molded article 15, the area where the gate can be installed becomes relatively wide. Therefore, the mold can be easily designed, and the gate can be provided at a position and in an optimum state for molding of each layer. In addition, there is an excellent effect that the degree of freedom in designing the molded product is improved and the design is facilitated. Moreover, since the gate traces of the respective gates from the first layer to the (N-1) th layer are covered by the subsequent layer molding or the Nth layer molding, the respective gates from the first layer to the (N-1) th layer are covered. The gate trace and the interface of the intermediate molded product are melted, and the minute unevenness and residual stress disappear. Therefore, when the multilayer molded article is an optical product such as a lens, there is an excellent effect that a multilayer molded article having excellent optical characteristics can be manufactured.

  Further, in the multilayer molded product 15 molded by the multilayer molding die 1 of the present embodiment, the gate trace 14 of the gate formed with the Nth layer appears only at the outer peripheral edge portion or in the vicinity thereof, and the other surface appears on the outer surface. Since the trace of the gate formed with this layer does not appear, the optical characteristic of the multilayer molded product is remarkably improved despite the provision of the gate of the intermediate molded product on the optical surface.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

  For example, the present invention can be applied to a combination of various modifications of the gate described above.

DESCRIPTION OF SYMBOLS 1 Mold apparatus 2 1st cavity block 3 2nd cavity block 4 1st mold plate 5 2nd mold plate 6 Mold cavity 6a-6h Mold cavity 7 Gate 7a-7h Gate 7i Gate 7j Gate 7k Gate 7l Gate 11a- 11 g Resin passage 12 Protruding portion 12 a to 12 g Protruding portion 13 Bar-like protrusion 14 Gate trace 15, 16, 17 Multilayer molded product 18, 19 Surface 20 A layer 21 B layer 22 to 27 Gate trace 28 to 31 Resin passage

Claims (8)

One or a plurality of first cavity blocks that form one side of the mold cavity with the same shape and size, and the other side of the mold cavity is the volume (volume) and height ( A second cavity block which is formed of protrusions or recesses having different depths and is paired with the first cavity block, one or a plurality of first templates for fixing the first cavity block, and the second cavity block A plurality of (N) which are formed by matching the first cavity block and the second cavity block and have different volumes from each other (N The intermediate molded product formed by injecting molten resin into each of the mold cavities in (1) is sequentially transferred and injected into the mold cavities having a larger volume of the mold cavities. In multilayer molding die apparatus for molding a multilayer molded article of repeated N layer,
For the (N-1) th layer, which is just before the Nth layer molding where the volume of the mold cavity is maximized, from the mold matching state for the first layer molding where the volume of the mold cavity is minimized. Each gate for supplying molten resin to each mold cavity in each mold matching state up to the mold matching state is provided at a position such that the gate trace of the gate does not appear on the outer surface of the multilayer molded product,
The gate for supplying the molten resin to the mold cavity in the mold-matched state for forming the Nth layer where the volume of the mold cavity is maximized is provided at a position corresponding to the outer surface of the multilayer molded product. A mold apparatus for multilayer molding.   The depth dimension of the concave portion that forms one side of each mold cavity and has the same shape and the same dimension is smaller than the maximum depth dimension of the concave portions that form the other side of each mold cavity. The mold apparatus for multilayer molding according to claim 1, wherein the mold apparatus is configured.   The mold apparatus for multilayer molding according to claim 1 or 2, wherein the gate provided at a position where a gate mark does not appear on the outer surface of the multilayer molded article is a pin gate or a hot runner.   The difference between the maximum height or maximum depth of the protrusion or recess for forming the Nth layer and the maximum height or maximum depth of the protrusion or recess for forming the (N-1) th layer is smaller than the layer order 4. The mold apparatus for multilayer molding according to claim 1, wherein the mold apparatus is configured to be smaller than the same difference between any of the layers. A multilayer molded product molded using the multilayer molding die apparatus according to any one of claims 1 to 4,
A multilayer molded product characterized in that a gate mark of a gate formed with an Nth layer is exposed on an outer surface thereof, and a mark of a gate formed with another layer is not exposed. A multilayer molded product molded using the multilayer molding die apparatus according to any one of claims 1 to 4,
The outer peripheral edge of the multilayer molded article is formed in one layer or two layers,
The multilayer molded product is characterized in that a portion excluding the outer peripheral end portion of the multilayer molded product is formed in an N layer. A multilayer molded product molded using the multilayer molding die apparatus according to any one of claims 1 to 4,
One surface of the multilayer molded article has a small curvature or a planar shape made of the first layer of the multilayer molding, and the other surface of the multilayer molded article has the Nth layer of the multilayer molding. A multilayer molded article having a curvature larger than that of a surface.   The multilayer molded article according to any one of claims 5 to 7, wherein the multilayer molded article is an optical lens.

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