JP2005074700A - Method and apparatus for molding resin molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the reduction of cost, the enhancement of a molding cycle and an increase in molding variation by simplifying the mold structure attached to an injection molding machine, in molding a resin molded product by pressing a resin plate-shaped product molded by the injection molding machine by the transfer plate arranged to the mold of a pressing machine to transfer a fine pattern to the resin plate-shaped product. <P>SOLUTION: The resin plate-shaped product A2 molded by the injection molding machine 1 is transferred to the gap between the mutually opposed molds 17 and 20 of the pressing machine 3 and the transfer plate 15 arranged to at least one of the molds 17 and 20 is brought into contact with/pressed to the transfer receiving surfaces B1 and B2 of the resin plate-shaped product A2 to transfer the fine pattern to the resin plate-shaped product A2. In this molding method of the resin molded product, the resin plate-shaped product A2 has a resin flow mark E on its transfer receiving surface B1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a molding method and a molding apparatus for a resin molded product in which a resin plate-like body molded by an injection molding apparatus is pressed by a transfer plate disposed in a mold of a press apparatus to transfer a fine pattern. Is.

  Conventionally, as a molding apparatus for a resin molded product that transfers a fine pattern by pressing a resin plate-like body that has been primarily molded with a transfer plate disposed in a die of a press apparatus, Patent Document 1, Patent Those described in Document 2 are known. Patent Document 1 describes that a light guide plate is obtained by compressing and pressing a resin sheet 1A with a resin molding machine. Although the method for forming the resin sheet 1A is not specified in Patent Document 1, generally, the resin sheet 1A is formed by an extruder, and the resin sheet 1A cut to a certain size by a cutting device is used. However, since the resin sheet 1A is extruded from the die of the extruder while the stress of the screw of the extruder remains, the resin sheet 1A formed by the extruder has a slightly wavy shape. Deflection occurs. And this wavelike bending becomes so remarkable that the resin sheet 1A becomes large area. Therefore, there is a problem that even if fine unevenness is transferred to the resin sheet 1A by a resin molding machine in a subsequent process, the transfer cannot be performed uniformly. Further, the molding of the resin sheet 1A by the extruder requires peripheral devices such as a take-up device and a cutting device, and requires a large facility.

As a solution to the above-mentioned problem, Patent Document 2 describes a press molding apparatus for an optical product that obtains an optical product by secondarily molding a resin plate A that has been primarily molded by an injection molding machine with a press molding apparatus 1. Has been. According to Patent Document 2, since the primary molded resin plate A is molded by an injection molding machine, there is no wave-like deflection as the resin plate molded by the above-described extruder. In the case where the resin plate A is molded by a conventional injection molding machine, the resin plate A is molded by a one-point side gate mold that does not leave a resin flow mark on the transfer surface of the resin plate A so as not to affect the optical characteristics of the optical product. A plate was being formed. However, molding the resin plate A, which is primarily molded using a one-point side gate mold, requires a longer resin flow path compared to molding using a direct gate mold, and the mold is installed by installing a hot runner. There is a problem that the structure becomes complicated and disadvantageous in terms of mold cost and running cost.
JP 2001-191348 A (Claim 1, FIG. 2, FIG. 4) JP 2003-1705 A (0002, 0011)

  Therefore, the present invention presses the resin plate-shaped body molded by the injection molding apparatus with a transfer plate disposed in the mold of the press apparatus, and when a resin molded product is molded by transferring a fine pattern, It is an object of the present invention to provide a molding method and a molding apparatus for a resin molded product which realizes cost reduction by simplifying a mold structure attached to an injection molding apparatus, an improvement in molding cycle, and an increase in molding variations.

  According to a first aspect of the present invention, there is provided a method for molding a resin molded article, wherein a resin plate-shaped body molded by an injection molding apparatus is transferred between opposing molds of a press apparatus, and the resin plate-shaped body is transferred. In a molding method of a resin molded product in which a fine pattern is transferred by abutting and pressing a transfer plate disposed on at least one of the molds to the surface, the resin plate-like body is a resin on the surface to be transferred. It is characterized by having flow marks.

  According to a second aspect of the present invention, there is provided a method for molding a resin molded product according to the first aspect, wherein the resin flow mark is a gate mark.

  According to a third aspect of the present invention, there is provided a method for molding a resin molded product according to the first aspect, wherein the resin flow mark is a weld mark.

  According to a fourth aspect of the present invention, there is provided a molding apparatus for a resin molded product, an injection molding apparatus for molding a resin plate-shaped body, a transfer device for transporting the resin plate-shaped body to a press apparatus, and a resin plate-shaped body. In a molding apparatus for a resin molded product, comprising: a press apparatus that transfers a fine pattern by abutting and pressing a transfer plate against a transfer surface; and the injection molding apparatus is a resin plate having a resin flow mark on the transfer surface A mold for molding the shaped body is provided, and the transfer device is configured to transfer the transfer surface of the resin plate-shaped body toward the transfer plate of the press device.

  The molding method and molding apparatus for a resin molded product according to the present invention transfer a fine pattern by pressing a resin plate-shaped body molded by an injection molding apparatus with a transfer plate disposed in a mold of a press apparatus. When molding resin molded products, the structure of the mold attached to the injection molding machine can be simplified by using a resin plate that is molded by the injection molding machine and having resin flow marks on the transfer surface. Can reduce costs, improve molding cycles, and increase molding variations.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic view showing a molding method and a molding apparatus for a light guide plate which is a resin molded product. FIG. 2 is a cross-sectional view of the press device. FIG. 3 is a view showing a resin plate that is injection-molded using a multipoint gate mold.

  An outline of a molding apparatus for a light guide plate, which is a resin molded product of the present embodiment, will be described with reference to FIG. Reference numeral 1 denotes an injection molding apparatus, and a fixed mold 7 and a movable mold 8 in which a cavity 6 is formed when the molds are aligned are respectively arranged on the fixed plate 4 and the movable plate 5. In this embodiment, the mold attached to the injection molding apparatus 1 has a gate 9 formed substantially at the center of the cavity forming surface 6a of the fixed mold 7, and a molten resin passage 11 is directed toward the injection apparatus 10 by a sprue bush (not shown). This is called a direct gate mold in which is formed. The cavity forming surface 6a of the fixed mold 7 is a portion that forms a transfer surface B1 of a sprue-shaped resin plate A1 with a sprue (hereinafter simply referred to as a resin plate A1) formed in the cavity 6. There are no stampers and special mirror finishes. In the present embodiment, the cavity forming surface 6b of the movable mold 8 is also a portion that forms the transfer surface B2 of the resin plate A1. The movable mold 8 is provided with an ejector device (not shown).

  In the injection molding apparatus 1 of the present embodiment, a fixed mold 7 and a movable mold 8 which are fixedly clamped so that the parting surfaces are in contact with each other are attached, and the resin plate A1 is molded. It is of the type to do. However, the injection molding apparatus 1 does not deny the use of an injection compression molding apparatus or an injection press molding apparatus that moves the movable mold after injection and compresses the molten resin in the cavity.

  In FIG. 1, 2 is a transfer device, which transfers the resin plate A1 molded by the injection molding device 1 to a press device 3 in a subsequent process. The transfer device 2 includes a gripping portion 12, an arm portion 13, a gate cut mechanism 14, and the like that suck and grip the resin plate A1, and each is operated by an actuator, air suction means, or the like (not shown). In this embodiment, the transfer device 2 has a function of taking out the resin plate A1 molded in the injection molding device 1, a gate cut function, and a resin plate A2 that is gate-cut to the press device 3 (hereinafter simply referred to as resin plate shape). Although it is abbreviated as the body A2, it is needless to say that the resin plate A2 corresponds to a resin plate formed by an injection molding apparatus. However, the functions of the transfer device 2 may be provided independently of each other or provided separately for the injection molding device 1 and the press device 3, respectively. For example, the injection molding apparatus 1 may have a gate cut function, and the resin plate A1 may be gate cut simultaneously with the opening of the movable mold 8.

  In FIG. 1, reference numeral 3 denotes a pressing device, which transfers and transfers a fine uneven pattern by bringing the transfer plate 15 into contact with and pressurizing the transfer surfaces B1 and B2 of the resin plate A2 transferred by the transfer device 2. The press device 3 will be described in detail with reference to FIG. 2. In the press device 3, the upper die 20 attached to the movable plate 19 is attached opposite to the lower die 17 placed on the bed 16. It has been. A ram 18 of a pressurizing cylinder, which is a pressurizing mechanism, is fixed to the movable platen 19, and the upper mold 20 is provided so as to be movable up and down with respect to the lower mold 17 by raising and lowering the ram 18. The pressurizing mechanism of the press device 3 is not limited to that using the ram 18 but may be another mechanism such as an electric motor.

  The lower mold 17 includes a cooling plate 21, a transfer plate 15 that performs transfer to the resin plate A2, and a transfer plate moving mechanism that moves the transfer plate 15 into and out of contact with the cooling plate 21. The parts of the lower mold 17 will be described in detail. The cooling board 21 mounted on the bed 16 has a plurality of temperature adjusting medium passages 22 formed therein and is controlled to a predetermined temperature. On the bed 16, holders 23 are attached in the vicinity of the cooling plate 21 in order to prevent a transfer plate 15 (described later) from being separated from the cooling plate 21 by a certain distance or more. Further, near the inner side of the holder 23 on the bed 16, one end of a spring 24 as a transfer plate moving mechanism for attaching and moving the transfer plate 15 to and from the cooling plate 21 is attached, and the other end of the spring 24 is attached to the other end of the spring 24. A holding portion 25 that holds the transfer plate 15 in contact with the holder 23 is fixed. As the transfer plate moving mechanism, an actuator such as a cylinder other than the spring 24 may be used.

  A plurality of electrodes are fixed to the holding portion 25, and the electrodes are connected to terminals 26, respectively. A transfer plate 15 is fixed to the holding portions 25 and 25. In this embodiment, the transfer plate 15 is a plate in which a rubber sheet 28 that is an insulator and is an elastic body is attached to the back surface of a stainless plate 27 having a thickness of 3 mm. The surface of the stainless steel plate 27 is a transfer surface 15a having fine unevenness for transferring a fine unevenness pattern to the transfer surface B1 of the resin plate A2. Further, the back surface of the rubber sheet 28 serving as the back surface of the transfer plate 15 is a contact surface with the surface of the cooling plate 21. Since the stainless plate 27 of the transfer plate 15 is thin, its heat capacity is smaller than that of the cooling plate 21. Further, the stainless steel plate 27 of the transfer plate 15 constitutes a heating mechanism together with the terminals 26 and the electrodes of the holding portion 25, and when the power is supplied from a power source (not shown) through the terminals 26 and the electrodes of the holding portion 25, resistance heat is generated. The

  In addition to the present embodiment, the transfer plate 15 may be one in which a stamper with a thickness of about 0.1 mm is separately attached to the surface of the stainless steel plate 27, and another metal plate is also provided on the back side of the rubber sheet 28. It may be arranged. As the fine unevenness of the transfer plate 15, it is possible to attach one that transfers various fine patterns such as dots and grooves that become the light exit surface of the light guide plate. The heating mechanism may be other methods such as induction heating.

  In the present embodiment, as with the lower mold 17, the upper mold 20 also has a cooling plate 21, a transfer plate 15 that generates resistance, and a transfer plate moving mechanism that moves the transfer plate 15 in contact with and away from the cooling plate 21. Is provided. A transfer plate 15 having fine irregularities may be disposed on one of the lower mold 17 and the upper mold 20, and a transfer plate having a mirror surface having no fine irregularities may be disposed on the other mold. The transfer plate 15 may not be disposed in other molds.

  Next, a method for forming a light guide plate which is a resin molded product of the present embodiment will be described. First, a transparent acrylic resin is supplied to the injection molding apparatus 1, and the resin plate A1 for the light guide plate is molded. However, the resin material used for the light guide plate may be polycarbonate, cycloolefin polymer, or the like. Also, the resin molded product molded from the resin material may be another optical product such as a light diffusion plate or a lens. Since the light guide plate formed in the present embodiment is a light guide plate having a uniform thickness, the resin plate-like body A1 formed by the injection molding apparatus 1 is also formed with a uniform thickness. When forming a wedge-shaped light guide plate, it is very difficult to form a wedge-shaped resin plate using an extruder, so the wedge-shaped resin plate formed by the injection molding apparatus 1 is used. Is done. Further, when the resin plate A1 is molded by using the injection molding apparatus 1, irregularities such as claw portions can be freely formed on the periphery of the light guide plate.

  The resin plate A1 is molded by the injection molding apparatus 1 in the cavity 6 formed between the fixed mold 7 which is a direct gate mold and the movable mold 8, as shown in (1) of FIG. The molten resin is injected and filled from the injection device 10 through the molten resin passage 11. The molten resin is cooled in the cavity 6 and in the molten resin passage 11, and a resin plate A1 having a sprue C fixed to the approximate center of the transfer surface B1 is formed. In this embodiment, by using the direct gate mold, it is possible to reduce the mold cost by simplifying the mold structure as compared with the one-point side gate mold. In addition, the direct gate mold can shorten the distance that the molten resin flows from the gate 9 into the cavity 6, so that the molding cycle can be improved by lowering the temperature of the molten resin, and the injection speed may be slow. There is also an effect.

  When the cooling of the resin plate A1 is completed, the mold is opened, and the resin plate A1 is projected by an ejector (not shown). At substantially the same time, the resin plate A1 is adsorbed by the grip portion 12 of the transfer device 2 and taken out from the injection molding device 1. In the present embodiment, the transfer surface B2 of the resin plate A1 is protruded by an ejector made of a normal protrusion pin, so that a protrusion mark is formed on the transfer surface B2. The protrusion mark is a press device 3 described later. It can be eliminated by molding.

  Next, as shown in FIG. 1 (2), the resin plate A1 taken out from the injection molding apparatus 1 by the transfer device 2 is gate-cut by the gate cut mechanism 14 of the transfer device 2, and the gate portion D The resin plate A2 and the sprue C are separated from the portion. However, the gate mark E, which is a resin flow mark, remains on the transfer surface B1 of the resin plate A2 for the light guide plate, and the entire transfer surface B1 is not completely uniform. (Thus, the direct gate mold corresponds to a mold in which the resin plate A2 having the gate mark E on the transfer surface B1 is formed.) Thereafter, the resin plate A2 is transferred to the press device 3 by the transfer device 2. The transfer plate 15 is placed with the transfer surface B1 on which the gate mark E remains remaining. In the example shown in FIG. 1, the transfer surface B1 of the resin plate A2 is directed to the right side in (2) of FIG. 1, but in FIG. 1 (3), the transfer surface B1 is the lower mold. 17 is transferred so as to be directed to the transfer plate 15 disposed at 17. In this embodiment, an example in which the resin plate A2 molded by the injection molding apparatus 1 is transferred to the press apparatus 3 as it is by the transfer apparatus 2 will be described. However, the resin plate body molded by the injection molding apparatus 1 is described. After a plurality of A2s are stocked, they may be continuously formed by the press device 3, and the forming place may be another place.

  In the press device 3, when the resin plate A2 is placed on the transfer plate 15, the transfer plate 15 and the cooling plate 21 are in a state of being separated by the extension of the spring 24. When the resin plate A2 is placed on the transfer plate 15 of the press device 3, the ram 18 is actuated to transfer the transfer plate 15 disposed on the upper mold 20 and the transfer surface of the resin plate A2. B2 (upper surface) is brought into contact, and the lowering of the upper mold 20 is stopped. At this time, the cooling plate 21 and the transfer plate 15 are still separated from each other. Then, the transfer plate 15 is energized, the transfer plate 15 is heated by resistance, and the transfer plate 15 is heated in a short time to a temperature higher than about 100 degrees which is the glass transition temperature of the resin plate A2 made of acrylic. Become. In this embodiment, when it is detected that the transfer plate 15 has reached a predetermined temperature (145 ° C. or 185 ° C. although the temperature rise temperature of the transfer plate 15 differs depending on the resin plate A2 to be molded), FIG. As shown in (4), the ram 18 is lowered again. When the transfer plate 15 and the cooling plate 21 come into contact with each other, the energization to the transfer plate 15 is stopped almost simultaneously, and a predetermined pressure (resin to be molded) is applied to the resin plate A2 via the transfer plate 15. The pressing force is different depending on the plate-like body A2 but is 1 MPa or 3 MPa. At the time of pressurization, energization to the transfer plate 15 is stopped as described above, and the transfer plate 15 and the cooling plate 21 are in contact with each other, so that the transfer plate 15 is rapidly cooled. The resin plate-like body A2 is pressed and pressed against the resin plate-like body A2 for a predetermined time (the pressure time varies depending on the resin plate-like body A2 to be molded, but 40 seconds or 80 seconds). Transfer is completed on the body A2, and a light guide plate on which a fine uneven pattern is formed is formed. At the end of pressurization, the temperature of the transfer plate 15 is about 40 ° C. or 65 ° C.

  Therefore, the press device 3 of the present embodiment can be heated to a high temperature in a short time by causing the transfer plate 15 to generate resistance heat, and the transferred surfaces B1 and B2 of the resin plate A2 that contacts the transfer plate 15 are in a molten state. Therefore, even if there is a gate mark E or a protruding mark on the transferred surfaces B1 and B2 of the resin plate A2, it can be easily eliminated. Then, by rapidly cooling the transfer plate 15 of the pressing device 3, it is possible to release the mold in a short time, and good transfer can be performed on the resin plate-like body A2. On the other hand, the press molding apparatus disclosed in Patent Document 2 cannot control the temperature of the stamper to be raised or lowered. Therefore, if pressurization is continued at a predetermined pressure or higher using a stamper in a high temperature state, it becomes difficult to release the mold, so that good transfer cannot be performed to the resin plate-like body, and the resin flow traces can be obtained in a short time. It was also difficult to eliminate such as.

  In the present embodiment, as described above, the light guide plate is formed by using the press device 3 in which the transfer plate 15 capable of changing and controlling the temperature is provided. It is not limited. For example, even if a heat press apparatus provided with a transfer plate whose temperature cannot be changed and controlled is used, it is possible to eliminate the gate mark E if the molding cycle is lengthened, and a transfer roller or the like is used as the press apparatus. It may be a thing.

  Next, the case where the resin plate-like body injection-molded using the multipoint gate mold is transferred by the press device 3 will be described with reference to FIG. A multi-point gate mold having a plurality of gates for one cavity is an effective mold for molding a resin plate having a small thickness and a large area, but is injected from each gate. Resin flow marks called weld marks remain in the portion where the molten resin collides. Therefore, conventionally, the multipoint gate mold has not been used for molding a resin plate for a light guide plate. Conventionally, a resin plate-like body for molding a light guide plate of about 14 inches or more keeps the gap in the thickness direction of the cavity before injection wider than the thickness of the resin plate-like body to be molded. After the molten resin was injected and filled into the cavity, it was molded by an injection press apparatus or the like to which an inlay mold for compressing the molten resin in the cavity was attached. However, the inlay mold and the injection press apparatus are complicated in structure, leading to an increase in cost. Also, the molding of the resin plate for molding a large light guide plate of 30 inches or more was difficult to inject and fill the molten resin into the cavity from the one-point side gate even using the inlay mold or the injection press device. Therefore, many products are manufactured by attaching an expensive prism sheet to a resin plate formed by an extruder.

  The multipoint gate mold in which the resin plate-like bodies A3 and A4 shown in (1) and (2) of FIG. 3 are molded solves the above problem. A resin plate A3 shown in (1) of FIG. 3 is molded by a multipoint gate mold in which side gates are provided on both sides of a cavity. Therefore, the resin plate A3 has runner portions F1 formed on both sides, and a weld mark G1 that is a groove having a depth of about 20 μm remains in the center of the resin plate A3. A resin plate A4 shown in (2) of FIG. 3 is molded by a multi-point gate mold in which four gates are formed in a portion of the cavity where the transfer surface is formed. Therefore, in the resin plate A4, the four runner portions F2 are fixed to the transfer surface B3, and the weld mark G2 remains in a portion where the molten resins injected and filled from the gates collide with each other. (Thus, the multipoint gate mold corresponds to a mold in which resin plate-like bodies A3 and A4 having weld marks G1 and G2 are formed on the transfer surface B3.)

  However, in the present invention, even if the resin plates A3 and A4 have the weld marks G1 and G2 as described above, the weld marks are formed by performing transfer molding with the press device 3 after the runner portions F1 and F2 are gate-cut. Resin flow traces such as G1 and G2 and gate traces after gate cutting can be eliminated. Therefore, by using the multipoint gate mold, the resin plate-like bodies A3 and A4 for the light guide plate can be molded without using a special high-cost one for the injection molding apparatus 1. Similarly to the direct gate mold, the multi-point gate mold can shorten the distance that the molten resin flows from the gate into the cavity compared to the single-point side gate mold. There are effects that the molding cycle is shortened by lowering the temperature and the injection speed may be slow. Furthermore, it becomes possible to easily mold resin plate-like bodies for large light guide plates of 30 inches or more with a multi-point gate mold, and it is possible to transfer and mold large light guide plates by pressing with a press device 3, and variations in molding are possible. Can be increased.

  As for the present invention, the case where the light guide plate which is an optical product is formed using a transparent resin material has been described in the above embodiment. However, the present invention is not limited to the molding. For example, when a fuel cell separator is molded from a resin material, the resin material contains a large amount of carbon and is opaque, and there is a problem in the fluidity of the molten resin. However, if the present invention is used, even if the material has a problem in fluidity, the resin material can be satisfactorily filled into the cavity by using the multipoint gate mold. For example, in a fuel cell separator, in order to increase the surface area, it is necessary to form a large number of fine uneven grooves on the surface. However, the press device 3 can form fine uneven grooves on the surface.

  Also, when molding resin molded products (including those with complicated shapes such as bends and cavities) such as personal computer frames by injection molding, weld marks and sink marks are used regardless of the number of gates. Resin flow traces such as these are likely to occur. However, according to the present invention, the surface of the resin molded product (resin plate-like body) after the injection molding is subjected to transfer molding again by the press device 3, so that the weld mark is processed while the surface is subjected to wrinkle processing or matte processing. You can make it less noticeable. In this example, the transfer plate is not limited to a perfect plane.

  The present invention is not enumerated one by one, but is not limited to the one described above, and it goes without saying that the present invention is also applied to those modified by a person skilled in the art based on the gist of the present invention.

It is the schematic which shows the shaping | molding method and shaping | molding apparatus of the light-guide plate which is a resin molded product. It is sectional drawing of a press apparatus. It is a figure which shows the resin plate-shaped object injection-molded using the multipoint gate metal mold | die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection molding apparatus 2 Transfer apparatus 3 Press apparatus 4 Fixed platen 5,19 Movable board 6 Cavity 6a, 6b Cavity formation surface 7 Fixed mold 8 Movable mold 9 Gate 10 Injection apparatus
DESCRIPTION OF SYMBOLS 11 Molten resin passage 12 Gripping part 13 Arm part 14 Gate cut mechanism 15 Transfer board 16 Bed 17 Lower mold 18 Ram 20 Upper mold 21 Cooling board 22 Temperature control medium path 23 Holder 24 Spring 25 Holding part 26 Terminal 27 Stainless steel board 28 Rubber sheet A1 Resin plate with sprue A2 Resin plate with gate cut A3, A4 Resin plate B1, B2, B3 Transfer surface C Sprue D Gate part E Gate trace F1, F2 Runner part G1, G2 Weld mark

Claims (4)

Transfer the resin plate molded by the injection molding device between the opposing molds of the press device,
Abutting and pressurizing a transfer plate disposed on at least one of the molds to the transfer surface of the resin plate-like body;
In the molding method of resin molded products that transfer a fine pattern,
The resin plate is
A method for molding a resin molded product, which has resin flow marks on a transfer surface.   The method for molding a resin molded product according to claim 1, wherein the resin flow trace is a gate trace.   The method for molding a resin molded product according to claim 1, wherein the resin flow mark is a weld mark. An injection molding apparatus for molding a resin plate,
A transfer device for transferring the resin plate-like body to a press device;
A press device for transferring a fine pattern by bringing a transfer plate into contact with and pressurizing the transfer surface of the resin plate-like body;
In a molding apparatus for resin molded products comprising:
The injection molding apparatus is provided with a mold for molding a resin plate-like body having resin flow marks on the transfer surface,
The said transfer apparatus transfers the to-be-transferred surface of a resin plate-shaped object toward the transfer plate of the said press apparatus, The molding apparatus of the resin molded product characterized by the above-mentioned.

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