JPWO2012111381A1 - Rotary injection molding machine for multilayer molded article, molding method for multilayer molded article, and multilayer molded article - Google Patents

Abstract

Provided are a rotary injection molding machine and a method for molding a multilayer molded product, which can form a thick multilayer molded product with high efficiency by forming each layer simultaneously. A fixed plate (11) for mounting one of the male and female molds (4) constituting n mold cavities (18) arranged at equal intervals on the circumference, and a male and female mold facing the fixed plate (11). A rotating disk (9) for attaching the other of the mold (4) to one of the male and female molds (4) so that the mold can be matched, a rotating device (5) for rotationally driving the rotating disk (9), and the matched male and female molds A mold clamping device (2) for clamping the mold (4), and an injection device (3) for injecting molten resin into the mold cavity (18) of the clamped male and female mold (4). One of the male and female molds (4) forming the mold cavity (18) has the same shape, and the other of the male and female molds (4) gradually increases from the smallest cavity volume to one side in the circumferential direction, The rotating device (5) is provided only on one side in the circumferential direction in which the cavity volume formed by the other of the male and female molds (4) increases sequentially. To rolling.

Description

  The present invention relates to a rotary injection molding machine for multilayer molded articles, a molding method for multilayer molded articles, and multilayer molded articles.

  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 by a conventional injection molding machine, the maximum thickness portion requires a long cooling time, so that the molding time is considerably long. For example, a thick plastic lens of about 25 mm requires a molding time of 15 minutes or more. Moreover, despite such a long molding time, sink marks remain in the thick portion, and the performance as a good lens could not be exhibited.

  In order to solve such a problem, Patent Document 1 discloses that the thickness is sequentially increased from one of the surfaces in the thickness direction of the resin thick lens, and finally the specified thickness. A multilayer technology is disclosed in which a plurality of dies are formed so as to reach the above, and the resin is injected a number of times for each dies while changing the dies on one side.

  Further, Patent Document 2 discloses a first mold plate that replaceably holds a core block for forming the back surface of a plastic molded product, and the first mold plate that can be freely opened and closed. A second mold plate that replaceably holds a cavity block for forming a portion excluding the portion, and a plurality of cavity blocks for forming the inner and outer layers of the plastic molded product, The core block is formed by a plurality of core blocks corresponding to the respective cavity blocks, and each of the core blocks and the respective cavity blocks are selectively used, and the first template and A multilayering technique in which the second template is held is disclosed.

JP 2001-191365 A JP 2001-322143 A

  However, the techniques of Patent Document 1 and Patent Document 2 described above are such that the core part of the mold is exchanged for each injection filling or the intermediate molded product up to the previous layer is placed in the cavity in order to form the next layer. There are a number of problems in that it requires a large number of processes and is extremely inefficient, requires a large number of cores to be stocked, and generates a lot of dust.

  The present invention has been made in view of the above-described problems, and a rotary injection molding machine capable of forming a multilayered product with high efficiency by simultaneously forming each layer of a multilayer by a single injection filling, and It aims at providing the shaping | molding method of a multilayer molded article.

  The present invention includes a first mold plate for mounting one of a plurality of (n) mold cavities arranged at equal intervals on the circumference, and the male and female facing the first mold plate. A second mold plate that attaches the other of the molds to one of the male and female molds so that the molds can be matched, a rotating device that rotationally drives one of the first mold plate and the second mold plate, and the mold A rotary injection molding machine comprising: a mold clamping device that clamps the combined male and female molds; and one or a plurality of injection devices that inject molten resin into the mold cavities of the clamped male and female molds The part of the male and female molds forming the mold cavities has the same shape, and the part of the male and female molds forming the mold cavities has the smallest cavity volume. The cavity volume increases sequentially from one side to the other in the circumferential direction. A cavity volume having the largest cavity volume and a cavity having the smallest cavity volume are provided adjacent to each other in the circumferential direction, and the rotating device has a cavity volume of each mold cavity formed by the male and female molds. The injection device rotates only to one side in the circumferential direction, and the injection device simultaneously injects and fills molten resin into each mold cavity formed based on the rotation of the rotation device to form each layer. A multilayer molded product having the same number of layers as the number n of the mold cavities is formed.

  According to this configuration, the mold cavities are provided at equal intervals on the circumference so as to sequentially increase the cavity volume, and the rotating device rotates one of the male and female molds without reversing the direction in which the cavity volume sequentially increases. Therefore, the sequential transfer of the intermediate molded product from the first layer formed by the mold cavity having the minimum cavity volume to the nth layer formed by the mold cavity having the maximum cavity volume can be carried out very smoothly and without dead time. Can do. Further, since each layer is uniform and relatively thin by this configuration, the cooling time at the time of forming each layer is shortened. Therefore, there is an excellent effect that a multilayer molded product in which each layer is laminated can be molded with high efficiency.

  The present invention is characterized in that the number n of the mold cavities is four to eight.

  According to this structure, a multilayer molded product can be molded efficiently and economically.

  According to the present invention, the depth dimension of the same shape part forming each mold cavity on one side of the male and female molds is the maximum depth of the part forming each mold cavity on the other side of the male and female molds. It is characterized by being smaller than the height dimension.

  According to this configuration, the area required for precision machining of the recesses forming the mold cavities is reduced, so that the mold machining cost can be reduced.

  The present invention is characterized in that at least one of the injection devices supplies molten resin to a plurality of mold cavities via a hot runner.

  According to this configuration, in-mold gate cutting is possible, yield can be improved by reducing runner loss, and gate balance generated when at least one of the injection devices supplies molten resin to the plurality of mold cavities is improved. Each mold cavity can be filled uniformly.

  The present invention is characterized in that at least one of the injection devices supplies molten resin to the plurality of mold cavities via branch pipes.

  According to this configuration, at least one of the injection devices can effectively and economically supply the molten resin to the plurality of mold cavities.

  The present invention is a multilayer molded article molded using the rotary type injection molding machine, wherein one surface of the multilayer molded article is composed of 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 a multilayer molded n-th layer and has a curvature larger than the curvature of the one surface.

  According to this configuration, it is possible to easily and inexpensively obtain a multilayer molded product in which the curvatures of both surfaces are different from each other.

  The present invention is a method of forming a multilayer molded article using the rotary injection molding machine, wherein molten resin is injected from the injection device into all the mold cavities when the male and female molds are pressed. The method further comprises n steps of separating the one and the other of the male and female molds from each other and rotating the rotating device 360 degrees / n only in the direction in which the volume of the mold cavity increases sequentially.

  According to this method, the rotation of 360 degrees / n in the direction in which the volume of the mold cavity is sequentially increased by the rotating device is performed by converting an intermediate molded product formed by a mold cavity having a small cavity volume into a mold having a larger cavity volume. Since the transfer to the cavity sequentially and the transition of the n-th layer process for forming the finished product to the intermediate layer product and the first layer process without the finished product are performed simultaneously, The direction of rotation of the device is the same. Therefore, the transfer of the intermediate molded product and the transition of the process are executed extremely smoothly and without a waste time. Further, this method makes each layer uniform and relatively thin, so that the cooling time at the time of forming each layer is shortened. Therefore, there is an excellent effect that a multilayer molded product in which each layer is laminated can be molded with high efficiency.

  The present invention is characterized in that the resin raw materials used in the injection apparatus are of the same type in all the injection apparatuses.

  According to this method, a molded product of one resin raw material can be molded with high efficiency.

  The present invention is characterized in that the resin raw materials used in the injection device are of different types in the injection device corresponding to both the first layer and the n-th layer or at least one of the first to n-th layers.

  According to this method, it is possible to easily form a layer having functions such as surface protection, filter, polarization, antireflection, and chromatic aberration suppression.

  The present invention is characterized in that the resin material used for the injection device is suitable for an optical lens.

  According to this method, a thick plastic lens can be molded with high efficiency.

FIG. 1 is a side view of a partial cross section showing a configuration of an injection molding machine (an example having eight mold cavities) according to an embodiment of the present invention. FIG. 2 is a side view of a partial cross section showing a state when the injection molding machine of FIG. 1 is opened. 3 is a cross-sectional view taken along the line III-III of FIG. 2 showing a mold cavity disposed on the rotating disk. FIG. 4A is a cross-sectional view showing a first layer mold cavity. FIG. 4B is a cross-sectional view showing a second layer mold cavity. FIG. 4C is a cross-sectional view showing a third layer mold cavity. FIG. 4D is a cross-sectional view showing a fourth layer mold cavity. FIG. 4E is a cross-sectional view showing a fifth layer mold cavity. FIG. 4F is a cross-sectional view showing a sixth layer mold cavity. FIG. 4G is a cross-sectional view showing a seventh layer mold cavity. FIG. 4H is a cross-sectional view showing an eighth layer mold cavity. FIG. 5 is a plan view showing a branch pipe together with another example of a male and female mold. FIG. 6 is a side view of a molded product molded with the most preferred male and female molds.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the injection molding machine 1 of this embodiment includes a mold clamping device 2, an injection device 3, a male and female mold 4, and a rotating device 5. The mold clamping device 2 includes a pressure-clamping / opening / closing mechanism (not shown), a movable platen 10, a rotating plate 9 rotatably attached to the movable platen 10, and a fixed platen 11 arranged to face the rotating plate 9. The fixed platen 11 and the tie bar 12 fixed to the pressing / opening / closing mechanism. The mold clamping device 2 clamps the male and female molds 4 through a movable plate 10 that slides on a fixed plate 11 and a rotating plate 9 and a tie bar 12 for mounting the male and female dies 4 by the action of a clamping and opening / closing mechanism. As shown in FIG. 2, the mold is opened. A known mechanism such as a hydraulic cylinder device or a toggle device is employed as the pressure clamping / opening / closing mechanism of the mold clamping device 2. The rotating device 5 includes a rotating disk 9, a servo motor 6, a pulley 7, and a belt 8. The rotating apparatus 5 rotates and positions the rotating disk 9 at an arbitrary rotation angle. The servomotor 6 is preferably employed in order to obtain a positioning rotation angle arbitrarily and accurately, but it may be based on a mechanism such as a cam. The rotating plate 9 and the rotating device 5 are illustrated as being provided on the movable platen 10, but may be provided on the fixed platen 11. Moreover, although the mold clamping apparatus 2 was illustrated as a horizontal type, it may be a vertical type.

  The male and female mold 4 includes a female mold plate 13 into which eight female cavity blocks 14a to 14h are inserted, and a male mold plate 16 into which eight male core blocks 15a to 15h are inserted. As shown in FIGS. 4A to 4H, the female cavity blocks 14a to 14h are formed so that the recesses have the same depth, and as shown in FIG. It is arranged. As shown in FIGS. 4A to 4H, the male core blocks 15a to 15h are formed so that the height of the projecting portion is sequentially reduced from 15a to 15h, and the circumference is the same as the female cavity blocks 14a to 14h. It arrange | positions so that it may become a space | interval. Therefore, the female cavity blocks 14a to 14h and the male core blocks 15a to 15h can be mold-matched in any combination based on the operation of the rotating device 5 and the mold clamping device 2. Then, as shown in FIGS. 4A to 4H, mold cavities 18a to 18h are formed so that the cavity volume sequentially increases in the rotation direction of the rotating device 5 (that is, in the present embodiment, the mold cavities of the mold cavities). The number n is 8.) Furthermore, the mold cavities 18a to 18h are sequentially increased from one having the smallest cavity volume (corresponding to the first layer) in one direction on the circumference, and having the largest cavity volume (corresponding to the eighth layer). The cavity volume is provided so as to be the smallest. The mold cavities 18 a to 18 h are provided with a gate 24 that communicates with the mold mating surface of the male and female molds 4. A hot runner 17 is embedded in the male mold plate 16 to freely open and close the molten resin passage between the nozzle 19 and the gate 24 of the injection device 3 to cut the mold gate. In addition, as shown in FIG. 5, it does not have an opening / closing function in place of the hot runner 17, but if the branch pipe 20 is used, it may be economically effective. Although the branch pipe 20 has shown an example of bifurcating, it may be branched into three or more. In addition, it is natural that the mounting positions of the male and female molds 4 and the embedding positions of the hot runner and the like change according to different forms of the mold clamping device 2 and the rotating device 5.

  Thus, the Example which provided the eight metal mold cavities 18a-18h in the one male and female metal mold | die 4 was demonstrated based on FIG. 1 thru | or FIG. 4A-FIG. On the other hand, as shown in FIG. 5, four male and female molds 21a to 21d having one mold cavity are placed on the turntable 9 so that the cavity blocks 22a to 22d are equally spaced on the circumference. You may arrange in. This configuration is effective in the case of a relatively large multilayer molded product, and the mold clamping device is often a vertical type. Further, in this configuration, the branch pipe 20 can be effectively employed instead of the nozzle 19.

  As described above, the concave portions forming the respective mold cavities in the female cavity block of the male and female mold 4 have the same shape, and the protrusions forming the respective mold cavities in the male cavity block of the male and female mold 4 have the same shape. The height dimension is smaller than the depth dimension of the recess of the female cavity block. However, the protrusions forming the respective mold cavities in the male cavity block of the male and female mold 4 may be changed so as to be concave. In addition, the depth dimension of each recess having the same shape in the female cavity block may be smaller than the depth dimension of the recess that is the largest of the protrusions or recesses forming each mold cavity in the male cavity block. Good. Such an arrangement is effective in reducing the processing cost of the recess. In particular, when the molded product is an optical lens, since the concave portion is an aspherical mirror surface, a remarkable effect is obtained.

  If the depth dimension of each recess of the same shape in the female cavity block is smaller than the depth dimension of the recess that is the largest of the protrusions or recesses forming each mold cavity in the male cavity block, the same shape The intermediate molded product molded by the mold cavity including the concave portions is the first layer of the multilayer molded product. Then, the intermediate molded product as the first layer is transferred to the mold cavity of the female cavity block to be matched with the male cavity block having a concave portion with a deeper concave portion as the rotating device 5 rotates. In the mold cavity to which the intermediate molded product as the first layer has been transferred, the second layer is laminated so as to overlap the first layer. Such a molding process is repeated until the n-th layer molding process which is the final molding process.

  The molded product 25 shown in FIG. 6 is an optical lens molded by a rotary injection molding machine for multilayer molded products equipped with a male and female mold having the configuration described in the previous section. The molded product 25 forms a lens surface 26 that is an aspherical or planar surface with a small curvature formed by one of the concave portions having the same shape in the female cavity block, and each mold cavity in the male cavity block. The lens surface 27 is an aspheric surface formed by the largest concave portion of the concave portions and having a curvature larger than the curvature of the lens surface 26. The lens surface 26 is the first layer of the multilayer molded product, and the lens surface 27 is the nth layer of the multilayer molded product. As described above, according to the male and female molds having the configuration described in the previous section, both lens surfaces having different curvatures of the optical lens can be formed easily and at low cost.

  The injection device 3 has a known mechanism such as a screw type or a plunger type, and is connected via a nozzle 19 or a branch pipe 20 to a male and female mold 4 which is molded and pressed with a molten resin produced by plasticizing a resin raw material. And injected into the cavities 18a to 18h. As shown in FIGS. 1 and 5, it is advantageous in terms of cost to provide a single injection device 3 for a plurality of mold cavities. However, it is possible to improve the added value of the product and control / moldability of injection filling. A plurality may be provided for improvement. In particular, when one injection device is provided for each mold cavity, the controllability and moldability of injection filling are improved.

  Next, the operation of multilayer molding using this injection molding machine 1 will be described.

  First of all, since the resin raw material supplied to the injection device 3 is made in order to solve the problems in the thick plastic lens molding, it is needless to say that those suitable for optical lenses are preferable. It is obvious that a thick molded product can be produced with high efficiency even when it is molded by the technique of the present invention using another resin raw material that is not for optical lenses.

  In the injection molding machine 1 shown in FIG. 1, the molten resin is injected from the injection device 3 into the male and female molds 4 clamped by the mold clamping device 2, and the mold cavities 18a to 18h are black in FIGS. 4A to 4H. As shown by the solid coating, each is simultaneously filled with a molten resin that flows over the entire surface. Thereafter, the intermediate molded product as the first layer formed in FIG. 4A is opened as it is attached to the female cavity block 14a as shown in FIG. 2, and the female mold plate 13 is rotated (360 degrees / 8) clockwise. And re-close to move to a position corresponding to the female cavity block 14b to prepare for the molding of FIG. 4B. Similarly, the intermediate molded product of FIG. 4B is sequentially transferred to FIG. 4C, and the intermediate molded product of FIG. 4G is sequentially transferred to FIG. 4H. The molded product of the eighth layer (n-th layer) that has been transferred eight times and molded in FIG. 4H is a finished product, and as shown in FIG. 2, the protruding means not shown together with the sprue 23 connected to the hot runner 17. The mold is released from the female cavity block 14h and taken out. That is, when the male and female molds 4 are pressed, the molten resin is injected from the injection device 3 into all the mold cavities 18a to 18h, the female plate 13 is separated from the male plate 16, and the rotating device 5 is moved. One multilayer molded article is molded by repeating a series of molding processes that are rotated only in a direction (360 degrees / 8) so that the volume of the mold cavity increases sequentially, eight times. Then, the rotation of the rotating device 5 after the molded product as a finished product molded in FIG. 4H is taken out is a transition to the next series of molding steps, and is performed simultaneously with the transfer of the intermediate molded product. Therefore, the rotation direction is such that the volume of the mold cavity is sequentially increased as in the previous molding step. That is, the rotating device 5 always rotates only in the same rotational direction during continuous molding.

  In each of the mold cavities 18b to 18h excluding the mold cavity 18a, an intermediate molded product is inserted. 4A to 4H, the outer shape of each of the mold cavity 18a and the substantial mold cavities 18b to 18h is such that the curvature of the lens as a multilayer molded product is different for each layer. However, since the outer shape of the multilayer molded product is the same, the substantial volume of the mold cavity 18a and each of the mold cavities 18b to 18h is a protrusion that sequentially changes in the male core blocks 15a to 15h. If the amount of change in height of the parts is the same, they are substantially the same. However, the substantial outer shape of each mold cavity may be reduced to be similar to the outer shape of the multilayer molded product by changing the shape of the convex portion of the male core block. At this time, the substantial volume of each mold cavity can be made uniform by adjusting the height of the convex part of the male core block.

  Making the volume of the mold cavity 18a substantially equal to the volume of each of the mold cavities 18b to 18h and making the substantial volumes of all the mold cavities substantially the same is effective for molding, in particular This is effective when injection and filling a plurality of mold cavities with a single injection device. It is also necessary to make the time of each process n times (n is the number of mold cavities) to be uniform and shortest. However, the front and back surfaces of the multilayer molded article or at least one of the layers, that is, both the first layer and the eighth (n) layer or only the first layer to at least one of the eighth to (n) layers are other layers. And may have a different thickness. In addition, the front and back surfaces of the multilayer molded product or at least one of the layers is molded using a resin raw material different from the resin raw materials of the other layers to provide functions such as surface protection, filter, polarization, antireflection, and chromatic aberration suppression. Sometimes it does. For example, by molding using two resin materials having different refractive indexes, it becomes possible to easily manufacture a laminated lens product such as an achromatic lens that suppresses chromatic aberration. In this case, it goes without saying that a separate injection device is required for each resin material.

  As is clear from the above detailed description, according to the rotary injection molding machine 1 of the present embodiment, all the portions of the male and female molds 4 forming the mold cavities 18a to 18h have the same shape. In the other part of the male and female molds 4, the mold cavities 18 a to 18 h are formed so that the cavity volume sequentially increases from the smallest cavity volume to one side in the circumferential direction, and the largest cavity volume and the cavity The rotating device 5 has a shape in which the smallest volume is provided adjacent to the circumferential direction, and the rotating device 5 has the circumferential direction in which the cavity volumes of the respective mold cavities 18a to 18h formed by the male and female dies 4 are sequentially increased. The injection device 3 rotates only on one side, and the injection device 3 simultaneously injects and fills molten resin into each mold cavity 18a to 18h formed based on the rotation of the rotation device 5. (In this embodiment n = 8) the number n of the mold cavity 18a~18h molding the same number of layers of the multilayer molded article by forming a layer. That is, the respective mold cavities 18a to 18h are provided at equal intervals on the circumference so as to sequentially increase the cavity volume, and the rotating device 5 does not invert one of the male and female molds 4 in the direction in which the cavity volume increases sequentially. Since the rotation is performed, the sequential transfer of the intermediate molded product from the first layer formed by the mold cavity 18a having the minimum cavity volume to the eighth layer formed by the mold cavity 18h having the maximum cavity volume can be performed extremely smoothly and without dead time. Can be executed. Further, since each layer is uniform and relatively thin by this configuration, the cooling time at the time of forming each layer is shortened. Therefore, there is an excellent effect that a multilayer molded product in which each layer is laminated can be molded with high efficiency.

  Further, according to the method for molding a multilayer molded product of the present embodiment, when the male and female molds 4 are pressed, the molten resin is injected from the injection device 3 into all the mold cavities 18a to 18h, and the male and female molds are formed. The step of rotating the rotating device 5 360 degrees / n (360/8 = 45 degrees in this embodiment) only in the direction in which the volume of the mold cavity is sequentially increased is n. There are 8 times (8 times in this embodiment). According to this method, the rotation of 360 ° / n in the direction in which the volume of the mold cavity is sequentially increased by the rotating device 5 causes the intermediate molded product formed by the mold cavity having a small cavity volume to be a mold having a larger cavity volume. Since the transfer to the mold cavity is sequentially performed and the process of the nth layer for forming the finished product is shifted to the process of the first layer without the intermediate formed product and the finished product at the same time. The rotating direction of the rotating device 5 is the same. Therefore, the transfer of the intermediate molded product and the transition of the process are executed extremely smoothly and without a waste time. Further, this method makes each layer uniform and relatively thin, so that the cooling time at the time of forming each layer is shortened. Therefore, there is an excellent effect that a multilayer molded product in which each layer is laminated can be molded with high efficiency.

  When a plastic lens having a thickness of 25 mm is molded with the male and female mold 4 having the eight mold cavities 18a to 18h described in this embodiment, the mold is closed, the male and female mold 4 is pressed, injected, cooled, A series of molding times of opening the mold, rotating the rotating disk, and taking out the molded product was 1 minute. If this is compared with 15 minutes which is the molding time by the conventional injection molding machine, it can be understood how highly efficient the injection molding machine of the present invention is.

  Therefore, if the number n of mold cavities is increased, the thickness of each layer is reduced accordingly, so that the cooling time is shortened and the efficiency becomes higher. However, for example, when molding a thick plastic lens having a thickness of 25 mm, the maximum thickness of each layer is 25 / n, and if there are eight mold cavities, the maximum thickness of each layer is about 3 mm. Moreover, the substantial thickness of the cavity is reduced in the gate direction on the outer periphery due to the convex lens shape. In order to allow the molten resin to flow well in such a narrow substantial cavity, the maximum thickness of each layer is preferably 3 mm or more. In consideration of the cost increase due to the additional mold cavities, the upper limit of the number n of mold cavities is eight. On the other hand, when the number of mold cavities is three, the maximum thickness of each layer is 8.3 mm, and the cooling time is not sufficiently shortened and the efficiency cannot be improved. Therefore, the preferable range of the number n of mold cavities is 4 to 8.

  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.

DESCRIPTION OF SYMBOLS 1 Injection molding machine 2 Clamping device 3 Injection device 4 Male and female metal mold 5 Rotating device 9 Rotating disc 10 Movable disc 11 Fixed disc 14a-14h Female cavity block 15a-15h Male core block 17 Hot runner 18a-18h Mold cavity 20 Branch Tube 22a-22h Cavity block 25 Molded product

Claims (10)

A first mold plate for mounting one of a plurality of (n) mold cavities arranged at equal intervals on the circumference, and the other of the male and male molds facing the first mold plate Is attached to one of the male and female molds so that they can be matched with each other, a rotating device that rotationally drives one of the first and second molds, and the matched male and female. In a rotary type injection molding machine comprising: a mold clamping device for clamping a mold; and one or a plurality of injection devices for injecting molten resin into the mold cavity of the clamped male and female molds,
All of the portions forming the mold cavities on one side of the male and female molds have the same shape,
The portion of each of the male and female molds that forms each of the mold cavities gradually increases from the smallest cavity volume to the one circumferential side, the largest cavity volume and the smallest cavity volume. Have a shape that is adjacent to the circumferential direction,
The rotating device rotates only on one side in the circumferential direction in which the cavity volume of each mold cavity formed by the male and female molds increases sequentially,
The injection apparatus is configured to form a plurality of layers by simultaneously injecting and filling molten resin into substantially each mold cavity formed based on the rotation of the rotating apparatus, thereby forming a multilayer having the same number of layers as the number n of the mold cavities. A rotary injection molding machine characterized by molding a molded product.   The rotary injection molding machine according to claim 1, wherein the number n of the mold cavities is four to eight.   The depth dimension of the same shape part that forms each of the mold cavities on one side of the male and female molds is smaller than the maximum depth dimension of the part that forms the respective mold cavities on the other side of the male and female molds. The rotary injection molding machine according to claim 1 or 2.   The rotary injection molding machine according to any one of claims 1 to 3, wherein at least one of the injection devices supplies molten resin to the plurality of mold cavities via a hot runner.   The rotary injection molding machine according to any one of claims 1 to 3, wherein at least one of the injection devices supplies molten resin to the plurality of mold cavities via branch pipes. A multilayer molded product molded using the rotary injection molding machine according to claim 3,
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. A method for molding a multilayer molded article using the rotary injection molding machine according to any one of claims 1 to 5,
When the male and female molds are clamped, molten resin is injected from the injection device to all the mold cavities, one and the other of the male and female molds are separated from each other, and the rotating device is moved to the mold cavity. A method for forming a multilayer molded product, comprising a step of rotating 360 degrees / n only in a direction in which the volume of the product gradually increases, n times.   The method for molding a multilayer molded product according to claim 7, wherein the resin raw materials used in the injection device are of the same type in all the injection devices.   The resin raw material used for the injection device is different in the injection device corresponding to both the first layer and the n-th layer or at least one of the first to n-th layers. A method for forming a multilayer molded article.   The method for molding a multilayer molded product according to any one of claims 7 to 9, wherein a resin raw material used for the injection device is suitable for an optical lens.

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