JP7352160B2 - Manufacturing equipment and manufacturing method for foamed resin molded products - Google Patents

Description

The present invention relates to an apparatus and method for manufacturing a foamed resin molded product.

A core-back method is known as a method for molding foamed resin molded products. According to this core-back method, a mold having a variable cavity volume is filled with a resin containing a foaming agent (hereinafter referred to as "foamed resin"). The foamed resin filled in the mold is cooled from the contact surface with the mold, forming a skin layer. Thereafter, when the temperature of the foamed resin within the cavity reaches an appropriate temperature, the volume within the cavity is expanded, thereby forming a core layer with a cellular structure inside the skin layer. The foamed resin molded product thus obtained is extruded from the mold by an ejector pin.

Japanese Patent Application Publication No. 5-42610

A resin molded product molded by the core-back method is extruded from the mold by an ejector pin provided on one of the molds. At this time, the force applied by the ejector pin is transmitted to the core layer through the skin layer, and the bubbles in the core layer are pressurized. As a result, the bubbles may burst due to the force applied by the ejector pin, the foaming gas in the area pushed by the ejector pin may spread to the surrounding area, causing the skin layer to separate from the core layer, or the surface of the foamed resin molded product may swell. The appearance of the molded product may be damaged.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a manufacturing apparatus and a manufacturing method that can eliminate the problems that may occur when taking out a foamed resin molded product from a mold, and can manufacture a foamed resin molded product that has an appearance of excellent quality. do.

In order to achieve this objective, the manufacturing apparatus according to the embodiment of the present invention increases the volume of the cavity formed on the separation surface of the first mold and the second mold from the first volume to the first volume. An apparatus for manufacturing a foamed resin molded product that foams a foaming agent contained in the resin filled in the cavity by increasing the volume to a second volume larger than the volume,
The separating surfaces of the first mold and the second mold are provided with a gate having one end communicating with the cavity,
The manufacturing device includes:
a first separating means that pushes the resin molded object filled in the cavity in a direction toward the first mold to separate the resin molded object from the second mold;
a second separating means that separates a molded part of the resin filled into the gate during molding from the molded resin before the first separating means separates the molded resin;
Equipped with
One of the first mold and the second mold has a first molding portion forming at least a part of the cavity,
The other of the first mold or the second mold has a second molding portion forming at least a part of the cavity,
The volume of the cavity can be changed from the first volume to the second volume by moving the second molded part in a reference direction with respect to the first molded part,
By moving the second molded part in the reference direction, the volume of the gate increases,
By separating the resin molded part filled in the gate from the resin molded body by the second separating means, gas is created between the gate and the resin molded part filled in the gate. A discharge path is formed .

Further, a manufacturing apparatus according to another embodiment of the present invention includes a plurality of molds that are separable in a reference direction, and injects a molding material into a cavity formed in a separation surface of the plurality of molds, thereby discharging the molding material into the cavity. A manufacturing device for obtaining a molded product having a shape corresponding to the
The plurality of molds have a first mold and a second mold,
A first cavity forming portion is formed on a first mold surface of the first mold that faces the second mold,
On a second mold surface of the second mold that faces the first mold, the first cavity forming portion is formed while the first mold and the second mold are in contact with each other. A second cavity forming portion is formed that cooperates with the cavity to form the cavity,
A first runner forming portion is formed on the first mold surface of the first mold,
A runner is formed on the second mold surface of the second mold in cooperation with the first runner forming portion while the first mold and the second mold are in contact with each other. A second runner forming portion is formed,
The second mold includes a gate that communicates the second runner forming part and the second cavity forming part,
The second mold includes a first ejector that can advance into the cavity from the second cavity forming part, and a first ejector that can advance from the second runner forming part before the first ejector advances into the cavity. and a second ejector capable of advancing into the runner ,
The second mold is movable forward and backward relative to the first mold, and in a state in which it is advanced toward the first mold, the second mold is connected to the first mold and the second mold. a first cavity space of a first volume is formed between the first mold and the second mold; having a cavity volume variable portion forming a second cavity space;
the second volume is larger than the first volume;
The second mold has a first runner having a first runner volume between the first runner forming part and the second runner forming part when the second mold is advanced toward the first mold. a runner that forms a space and forms a second runner space with a second runner volume between the first runner forming part and the second runner forming part when retracted from the first mold; has a volume variable part,
the second runner volume is larger than the first runner volume;
With the second mold retracted from the first mold, the second ejector advances into the runner to create a shape corresponding to the second runner space and the first runner space. A gas discharge passage is formed between the molded part and the molded part .

According to the present invention, the resin molded part filled in the gate is separated from the resin molded body filled in the cavity, and the gas in the core layer is discharged, so that when the foamed resin molded product is taken out from the mold. It is possible to provide a manufacturing apparatus and a manufacturing method that can solve the problems that may occur in the manufacturing process and can manufacture a foamed resin molded product having an appearance of excellent quality.

1 is a schematic diagram showing a schematic configuration of an injection molding apparatus for a foamed resin molded product according to an embodiment. 2 is a schematic diagram showing a schematic configuration of a mold of the injection molding apparatus shown in FIG. 1. FIG. 2 is a schematic diagram showing a schematic configuration of a mold of the injection molding apparatus shown in FIG. 1. FIG. 2 is a schematic diagram showing a schematic configuration of a mold of the injection molding apparatus shown in FIG. 1. FIG. 2 is a schematic diagram showing a schematic configuration of a mold of the injection molding apparatus shown in FIG. 1. FIG. FIG. 3 is a schematic diagram showing a schematic configuration of a mold of an injection molding apparatus for a foamed resin molded product according to another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an apparatus for manufacturing a foamed resin molded product according to the present invention will be described with reference to the accompanying drawings.

[Forming equipment]
FIG. 1 shows an outline of an injection molding apparatus for a foamed resin molded product according to an embodiment. The illustrated injection molding apparatus 10 has a first structure (injection section) 12 disposed on the right side of the figure and a second structure (molding section) 14 disposed on the left side of the figure.

The first structure 12 includes a molten resin injection section 16 . The molten resin injection section 16 has a substantially cylindrical cylinder (barrel) 18 extending in the left-right direction in the figure. Cylinder 18 has an injection nozzle 20 in the vicinity of second structure 14 . The injection nozzle 20 is connected to a resin injection port 22 (see FIGS. 2 to 5) provided in the second structure 14, which will be described later.

The cylinder 18 includes a heating section 24 that heats and melts the resin. The opposite side of the cylinder 18 to the injection nozzle 20 is connected to a foamed resin supply section 26 that supplies foamed resin.

The cylinder 18 has a built-in screw 28. The screw 28 is connected to a screw drive section 30.

The heating section 24, the foamable resin supply section 26, and the screw drive section 30 are connected to a control section 32, and their operations are controlled based on instructions from the control section 32.

[Molding mold]
The second structure 14 includes a mold 34 that molds the molten foamed resin supplied from the first structure 12 into a predetermined shape. The molding die 34 has an upper die (first die) 36 and a lower die (second die) 38. The upper mold 36, the lower mold 38, or both are supported so as to be movable in the vertical direction (reference direction). In the embodiment, the upper mold 36 is fixed. The lower mold 38 is supported so as to be movable up and down, and is drivingly connected to a mold drive section 40 that moves the lower mold 38 in the vertical direction.

[cavity]
As shown in FIG. 2, the upper mold 36 has an upper mold surface (first mold surface) 42 facing the lower mold 38, and the lower mold 38 has a lower mold surface 42 facing the upper mold 36. A mold surface (second mold surface) 44 is provided, and a mold separation surface formed by combining the upper mold surface 42 and the lower mold surface 44 is provided with a cavity having a shape corresponding to the external shape of the molded product. 46 is formed. The cavity 46 is formed by an upper cavity forming portion (first cavity forming portion or first molding portion) 48 formed on the lower mold opposing surface (first mold surface) of the upper mold 36 and a lower mold. The upper mold has a lower cavity forming portion (second cavity forming portion, second molding portion, or cavity volume variable portion) 50 formed on the upper mold opposing surface (second mold surface) of 38; With the upper mold surface 42 of the mold 36 and the lower mold surface 44 of the lower mold 38 in contact with each other, a molded body 110 (see FIGS. 4 and 5) is placed between the upper cavity forming part 48 and the lower cavity forming part 50. ) is formed.

In the embodiment, the upper cavity forming portion 48 consists of a concave portion toward the lower mold 38, and the lower cavity forming portion 50 consists of a convex portion toward the upper mold 36.

The upper cavity forming portion 48 is formed with an upper wall portion 52 extending in the left-right direction in the figure, and a first peripheral wall (inner wall) 54 extending in the reference direction from the outer peripheral end of the upper wall portion 52 toward the lower mold 38. There is. The lower cavity forming portion 50 includes a lower wall portion 56 extending in the left-right direction in the figure, and a second peripheral wall (outer wall) 58 extending in the reference direction from the outer peripheral end of the lower wall portion 56 toward the upper mold 36. There is. The first peripheral wall 54 and the second peripheral wall 58 have the same shape and size when viewed from the reference direction. The height of the first peripheral wall 54 (length in the reference direction) is greater than the height (length in the reference direction) of the second peripheral wall 58. Therefore, as shown in FIG. 2, when the upper mold surface 42 of the upper mold 36 and the lower mold surface 44 of the lower mold 38 are in contact with each other, the upper wall portion 52 of the upper mold 36 and the lower mold surface 44 of the lower mold 38 are in contact with each other. A first cavity space 60 consisting of a first closed space having a first volume is formed between the upper mold surface 42 of the upper mold 36 and the lower wall portion 56 of the upper mold 36. With the lower mold surface 44 of the mold 38 separated, the air is removed from a second closed space having a second volume between the upper wall 52 of the upper mold 36 and the lower wall 56 of the lower mold 38. A second cavity space 62 is formed.

In the embodiment, the lower wall portion 56 of the lower mold 38 is formed with one or more grooves (rib forming portions) 64 extending in the reference direction in a direction away from the upper mold 36 .

[Runner]
One or more runners 66 are formed around the cavity 46 . In the embodiment, the runner 66 includes a concave upper runner forming portion (first runner forming portion) 68 formed on the upper mold surface 42 and a concave lower runner forming portion (second runner forming portion) formed on the lower mold 38. As shown in FIG. 1, when the upper mold surface 42 of the upper mold 36 and the lower mold surface 44 of the lower mold 38 are in contact (the mold closed state), A runner 66 is formed between the upper runner forming portion 68 and the lower runner forming portion 70.

In the embodiment, for example, the interface between the upper mold 36 and the lower mold 38 (specifically, the upper mold surface 42 or the lower mold surface 44 or both) has one end communicating with the runner 66 and the other. A sprue 72, which is a resin supply passage whose end communicates with the resin injection port 22, and an air vent (not shown) for discharging air or gas within the cavity 46 during injection molding are formed.

[Tunnel Gate]
The lower mold 38 has a tunnel gate 74 formed therein that communicates the lower runner forming portion 70 and the lower cavity forming portion 50. In the embodiment, the tunnel gate 74 tapers from the lower runner forming portion 70 toward the lower cavity forming portion 50 . Further, the tunnel gate 74 is formed along an arch-shaped curve connecting the lower runner forming portion 70 and the lower cavity forming portion 50.

In this embodiment, the runners 66 are formed by concave upper runner forming portions 68 and lower runner forming portions 70 on the upper mold surface 42 of the upper mold 36 and the lower mold surface 44 of the lower mold 38, respectively. A concave runner forming portion may be formed only in one of the upper mold 36 and the lower mold 38, and a flat mold surface may be used for the runner forming portion of the other mold.

[Ejector]
The lower mold 38 also includes one or more first ejector passages 76 that extend straight downward (in a direction away from the upper mold 36) from the lower wall 56 of the lower cavity forming portion 50, and a lower runner. One or more second ejector passages 78 are formed that extend straight from the bottom of the forming portion 70 downward (in the direction away from the upper mold 36). As shown, at least one of the second ejector passages 78 is preferably located near the tunnel gate 74.

A first ejector pin (first ejector) 80 is inserted into the first ejector passage 76 . The first ejector pin 80 is connected to a first ejector pin drive section 82, and based on the drive of the first ejector pin drive section 82, as shown in FIGS. A lowered position where the upper end surface is located at the same height as the lower wall 56 of the lower cavity forming portion 50, and a raised position where the upper end of the first ejector pin 80 protrudes upward from the lower wall 56 of the lower cavity forming portion 50. It is designed to move between positions. In FIG. 5, the upper end of the first ejector pin 80 is located halfway from the lowered position to the raised position, and is configured to be able to move further toward the raised position.

A second ejector pin (second ejector, separation means) 84 is inserted into the second ejector passage 78 . The second ejector pin 84 is drivingly connected to a second ejector pin drive section 86, and based on the drive of the first ejector pin drive section 82, as shown in FIGS. The lowered position in which the upper end of the second ejector pin 84 is located at the same height as the bottom surface of the lower runner forming part 70, and the lowered position in which the upper end of the second ejector pin 84 is located at the same height as the bottom surface of the lower runner forming part 70, and the upper end of the second ejector pin 84 protrudes upward from the bottom surface of the lower runner forming part 70, as shown in FIG. It is designed to move between the raised position and the raised position.

[Cooling passage]
A first coolant circulation path 88 and a second coolant circulation path 90 for cooling the molten resin injected into the cavity 46 are formed in the upper mold 36 and the lower mold 38, respectively. A coolant circulation path 88 and a second coolant circulation path 90 are connected to a coolant supply and recovery device 94 via a coolant supply and recovery path 92 . Although not shown, the coolant supply and recovery device 94 includes a pump that circulates the coolant and a cooler that cools the coolant that has recovered heat through heat exchange with the high-temperature resin.

The mold drive unit 40 , the first ejector pin drive unit 82 , the second ejector pin drive unit 86 , and the coolant supply and recovery device 94 are connected to the control unit 32 , and respond to signals output from the control unit 32 . Based on this, the mold drive section 40, the first ejector pin drive section 82, the second ejector pin drive section 86, and the coolant supply and recovery device 94 are configured to be driven.

[Molding process]
The molding process based on the control of the control unit 32 will be explained.
The foamed resin supply section 26 stores foamed resin in which a resin and a foaming agent are mixed. As the resin, thermoplastic resins such as polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polyurethane (PUR), polycarbonate (PC), and nylon are used. The blowing agent may be a chemical blowing agent, a physical blowing agent, or an expandable microcapsule. When forming fine bubbles, it is preferable to use supercritical nitrogen or carbon dioxide as the blowing agent.

As shown in FIG. 1, the upper mold 36 and the lower mold 38 of the molding mold 34 are in a state where the upper mold surface 42 of the upper mold 36 and the lower mold surface 44 of the lower mold 38 are in contact with each other. Closed.

From this state, the control unit 32 supplies foamed resin from the foamed resin supply unit 26 into the cylinder 18 .

The control unit 32 drives the screw drive unit 30 to rotate the screw 28 around the axis. The control unit 32 also activates the heating unit 24 to heat and melt the foamed resin 96 introduced into the cylinder 18 . For example, polypropylene has a melting point of 165°C, so it is generally heated to 200-305°C.

Based on the rotation of the screw 28, the molten foamed resin 96 flows from one or more injection ports 22 of the mold 34 through the sprue 72, the runner 66, and the tunnel gate 74 into the cavity 46 (the first volume is The air or gas in the cavity 46 is replaced by the air or gas in the cavity 46. The replaced air or gas is exhausted through an air vent (not shown) (see FIG. 2).

The filled foamed resin 96 also fills the grooves 64 formed in the lower mold 38 to form reinforcing ribs 98.

At this time, the coolant supply and recovery device 94 is driven based on a command from the control unit 32, and the coolant is circulated in the coolant circulation paths 88 and 90 of the upper mold 36 and the lower mold 38. Therefore, the foamed resin 96 filled in the cavity 46 is cooled to about 70° C. to 120° C., particularly the resin portion that contacts the inner surface of the cavity 46, and a skin layer 100 is formed there.

Thereafter, the control section 32 drives the mold drive section 40 to lower the lower mold 38 (see FIG. 3). The amount of descent of the lower mold 38 is smaller than the height of the peripheral wall 58 of the lower cavity forming portion 50 in the lower mold 38. Thereby, the cavity 46 is expanded into a second cavity space 62 having a second volume larger than the first volume, and negative pressure is introduced into the cavity 46 . As a result, the foaming agent contained in the foamed resin 96 is foamed to form a core layer 102 made of a foam inside the skin layer 100. In the core layer 102, closed cells and open cells may exist alone, or a mixture of closed cells and open cells may be present.

Next, the control unit 32 drives the second ejector pin drive unit 86 to cause the second ejector pin 84 to protrude into the runner 66. (See FIG. 4) As a result, the molded portion 104 made of foamed resin filled in the runner 66 is pushed upward and lifted from the runner 66. At this time, tension is applied to the elongated molded portion 106 made of foamed resin filled in the tunnel gate 74 in its longitudinal direction. In the embodiment, the tunnel gate 74 gradually becomes thinner from the runner 66 toward the cavity 46, so the molded portion 106 filled in the tunnel gate 74 breaks at its tip (the connection between the tunnel gate 74 and the cavity 46). do. Further, the molded portion 106 of the tunnel gate 74 is pulled by the molded portion 104 of the runner 66 and moves away from the cavity 46, and a gas exhaust path 108 is formed around the molded portion 106 of the tunnel gate 74.

Therefore, when the molded part 106 of the tunnel gate 74 is separated from the molded body (foamed resin molded product) 110 formed inside the cavity 46, the gas contained in the core layer 102 causes the tunnel gate 74 of the molded body 110 to break. It is discharged from the department. As described above, since the core layer 102 includes not only closed cells but also open cells, gas escapes from the entire molded body 110.

Next, the control unit 32 moves the lower mold 38 downward to form a molded body removal space between the upper mold 36 and the lower mold 38, as shown in FIG. Subsequently, the control unit 32 drives the first ejector pin drive unit 82 to raise the first ejector pin 80 and separate the molded body 110 from the lower mold 38. (FIG. 5 shows that the upper end of the first ejector pin 80 is at a halfway position before reaching the raised position where the molded body 110 is separated from the lower mold 38.)

At this time, since the molded body 110 is in close contact with the lower mold 38, a large force is applied to the first ejector pin 80. In particular, when separating the molded body 110 having the reinforcing ribs 98, the force applied to the molded body 110 from the first ejector pin 80 is even greater. Further, the force applied to the molded body 110 from the first ejector pin 80 is transmitted from the skin layer 100 on the surface of the molded body to the core layer 102 inside the molded body, and applies pressure to the foam contained in the core layer 102. . However, as described above, since the excess gas in the core layer 102 has already been exhausted, the gas bubbles pushed by the first ejector pin 80 may burst, or the gas bubbles pushed by the first ejector pin 80 may burst. The gas will not spread to the surroundings and separate the skin layer 100 from the core layer 102, or will not break through the skin layer 100 and blow out. Therefore, the appearance of the molded body 110 made of foamed resin is not impaired.

[Other embodiments]
In the above description, the lower cavity forming part 50 is integrally formed in the lower mold 38, but as shown in FIG. It is composed of a lower mold part (main body part) 210 and a second lower mold part (movable part) 212 that can move forward and backward with respect to the upper mold 36, and the second lower mold part 212 is connected to the upper mold part. 36, the volume of the cavity 46 formed between the upper mold 36 and the lower mold 38 is divided into a first volume and a second volume larger than the first volume. It may be made to vary between.

Further, the above-mentioned upper mold and lower mold may each be divided into an arbitrary number of parts.

Further, the tunnel gate may be an arch-shaped gate (banana gate) as described above, or a linear gate (submarine gate) as shown in FIG. 6.

In the above description, in order to facilitate understanding of the invention, the ejector pin and the tunnel gate are provided in the lower mold, but the ejector pin and the tunnel gate may be provided in the upper mold instead of the lower mold. Alternatively, the molding mold may be separated into left and right parts, and the mold may be configured as a left mold and a right mold, and the ejector pin and tunnel gate may be formed in one mold.

10: Manufacturing equipment (injection molding equipment)
36: First mold (upper mold)
38: Second mold (lower mold)
46: Cavity 74: Gate 84: Separation means (second ejector pin)
106: Molded part of resin filled in the gate (molded part of tunnel gate)
110: Foamed resin molded product

Claims (7)

Filling the cavity by increasing the volume of the cavity formed on the separation surface of the first mold and the second mold from the first volume to a second volume larger than the first volume. An apparatus for manufacturing a foamed resin molded product that foams a foaming agent contained in a resin,
The separating surfaces of the first mold and the second mold are provided with a gate having one end communicating with the cavity,
The manufacturing device includes:
a first separating means that pushes the resin molded object filled in the cavity in a direction toward the first mold to separate the resin molded object from the second mold;
a second separating means that separates a molded part of the resin filled into the gate during molding from the molded resin before the first separating means separates the molded resin;
Equipped with
One of the first mold and the second mold has a first molding portion forming at least a part of the cavity,
The other of the first mold or the second mold has a second molding portion forming at least a part of the cavity,
The volume of the cavity can be changed from the first volume to the second volume by moving the second molded part in a reference direction with respect to the first molded part,
By moving the second molded part in the reference direction, the volume of the gate increases,
By separating the resin molded part filled in the gate from the resin molded body by the second separating means, gas is created between the gate and the resin molded part filled in the gate. A manufacturing device characterized in that a discharge path is formed . the first molded portion has a concave portion;
the second molded portion has a convex portion;
The manufacturing apparatus according to claim 1, wherein the convex portion is capable of moving forward and backward toward the concave portion. A runner communicating with the gate is formed on the separation surface of the first mold and the second mold,
The second separating means separates the resin molded part filled in the gate from the resin molded body filled in the cavity by pushing the resin molded part filled in the runner during molding. The manufacturing apparatus according to claim 1 or 2, characterized in that: . Using the manufacturing apparatus according to any one of claims 1 to 3 ,
forming the cavity having the first volume on a separation surface between the first mold and the second mold;
filling the resin into the cavity having the first volume through the gate;
foaming the foaming agent contained in the resin by increasing the volume of the cavity from the first volume to the second volume;
urging the resin molded part filled in the gate in a direction away from the cavity to separate it from the resin molded part filled in the cavity;
separating the first mold from the resin molded product while leaving the resin molded product in the second mold;
A method for manufacturing a foamed resin molded product, comprising pushing the resin molded product in a direction toward the first mold to separate the resin molded product from the second mold. A manufacturing apparatus comprising a plurality of molds that are separable in a reference direction, and injecting a molding material into cavities formed in separation surfaces of the plurality of molds to obtain a molded product having a shape corresponding to the cavities,
The plurality of molds have a first mold and a second mold,
A first cavity forming portion is formed on a first mold surface of the first mold that faces the second mold,
On a second mold surface of the second mold that faces the first mold, the first cavity forming portion is formed while the first mold and the second mold are in contact with each other. A second cavity forming portion is formed that cooperates with the cavity to form the cavity,
A first runner forming portion is formed on the first mold surface of the first mold,
A runner is formed on the second mold surface of the second mold in cooperation with the first runner forming portion while the first mold and the second mold are in contact with each other. A second runner forming portion is formed,
The second mold includes a gate that communicates the second runner forming part and the second cavity forming part,
The second mold includes a first ejector that can advance into the cavity from the second cavity forming part, and a first ejector that can advance from the second runner forming part before the first ejector advances into the cavity. and a second ejector capable of advancing into the runner ,
The second mold is movable forward and backward relative to the first mold, and in a state in which the second mold is advanced toward the first mold, the first mold and the second mold are connected to each other. a first cavity space of a first volume is formed between the first mold and the second mold; having a cavity volume variable portion forming a second cavity space;
the second volume is larger than the first volume;
The second mold has a first runner having a first runner volume between the first runner forming part and the second runner forming part when the second mold is advanced toward the first mold. a runner that forms a space, and forms a second runner space of a second runner volume between the first runner forming part and the second runner forming part when retracted from the first mold; has a volume variable part,
the second runner volume is larger than the first runner volume;
With the second mold retracted from the first mold, the second ejector advances into the runner to create a shape corresponding to the second runner space and the first runner space. A manufacturing apparatus characterized in that a gas exhaust path is formed between the molded part and the molded part . 6. The manufacturing apparatus according to claim 5, wherein the cavity volume variable portion is a part of the second mold that is integrally formed with the second mold. The second mold has a main body portion and a movable portion that can move forward and backward in the reference direction with respect to the main body portion,
6. The manufacturing apparatus according to claim 5 , wherein the main body portion constitutes the cavity volume variable portion.

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