Molding mold and its manufacturing method

Abstract

To prevent deformation of a shell mold by backing up the shell mold sufficiently with a backup mold, and to increase vacuum suction efficiency by connecting all vacuum suction holes in the shell mold to a ventilation groove.SOLUTION: A mold for molding includes a shell mold with a plurality of vacuum suction holes 5 and a backup mold. A back surface of a shell body part 3 and a surface of a backup body part 11 are identically shaped and mated. A vent groove 13 is formed on a surface of the backup body part 11 or a back surface of the shell body part 3, leaving a receiving surface 14 to receive a mating surface. On a back surface of the shell body part 3 or a surface of the backup body part 11, a plurality of striations 6 with a feed pitch of 0.5 to 5.0 mm and a machining depth of 0.01 to 0.4 mm and a protrusion 7 between the striations are formed. The vacuum suction hole 5 and the vent groove 13 are connected through the striations 6.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a molding die having a vacuum suction function. [Background technology]

[0002] Many molding dies capable of vacuum-suctioning a sheet onto a mold surface are comprised of a relatively thin shell mold with multiple vacuum suction holes and a backup mold that backs up the shell mold. This is because multiple vacuum suction holes are easy to form in a relatively thin shell mold. On the other hand, the backup mold must be designed to support the shell mold while providing an air passage that communicates with the vacuum suction holes.

[0003] The backup mold described in Patent Document 1 has a storage recess that is slightly larger than the back surface of the shell mold and multiple support protrusions that protrude from the storage recess, which support the back surface of the shell mold. The storage recess serves as an air passage that communicates with the vacuum suction hole of the shell mold, reducing the pressure in the storage recess from outside the mold. However, with this backup mold, the support protrusions are unable to adequately support the shell mold when the molding pressure is high, which could cause the shell mold to deform.

[0004] The backup mold described in Patent Document 2 has a surface that matches the back surface of the shell mold, and has ventilation grooves recessed into the surface, leaving multiple receiving surfaces, which support the back surface of the shell mold. The vacuum suction holes in the shell mold are connected to ventilation grooves that function as air passages, and pressure is reduced in the ventilation grooves from outside the mold through the ventilation holes. This backup mold can adequately support the shell mold and prevent deformation of the shell mold even under high molding pressure. However, with this backup mold, not all vacuum suction holes are necessarily connected to the ventilation grooves, and some vacuum suction holes may be completely blocked by the receiving surfaces, reducing the overall vacuum suction efficiency. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 61-14922 [Patent Document 2] Patent Publication No. 2021-53920 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to sufficiently back up the shell mold with a backup mold to prevent deformation of the shell mold, and to connect all of the vacuum suction holes in the shell mold to the ventilation grooves, thereby improving the vacuum suction efficiency. [Means for solving the problem]

[0007] [1] Molding mold A molding die includes a shell mold having a plurality of vacuum suction holes and a backup mold that backs up the shell mold, and the back surface of the shell mold and the front surface of the backup mold are fitted together with the same shape, A ventilation groove is formed on the surface of the backup mold or the back surface of the shell mold, leaving a receiving surface for receiving the mating surface; A plurality of grooves with a feed pitch of 0.5 to 5.0 mm and a processing depth of 0.01 to 0.4 mm and ridges between the grooves are formed on the back surface of the shell mold or the surface of the backup mold (however, the surface on which the ventilation grooves are processed is referred to as the "receiving surface"); A molding die characterized in that vacuum suction holes and ventilation grooves communicate with each other via grooves.

[0008] <effect> Since the rear surface of the shell mold and the front surface of the backup mold, which have the same shape, come into contact with each other at the protrusions, the shell mold can be sufficiently backed up by the backup mold, preventing deformation of the shell mold. Since the vacuum suction holes and the ventilation grooves are connected via the grooves, all the vacuum suction holes of the shell mold can be connected to the ventilation grooves, thereby improving the vacuum suction efficiency. By providing multiple grooves with a feed pitch of 0.5 to 5.0 mm and a processing depth of 0.01 to 0.4 mm, it is possible to achieve both vacuum suction efficiency and shell mold rigidity. If the processing pitch is less than 0.5 mm and the processing depth is less than 0.01 mm, vacuum suction efficiency will decrease. If the processing pitch is more than 5.0 mm and the processing depth is more than 0.4 mm, when this is formed into a shell mold, the shell mold will deform slightly due to the pressure during molding, affecting the dimensional accuracy of the molded product and the durability of the mold.

[0009] [2] Manufacturing method of molding die A method for manufacturing a molding die including a shell die having a plurality of vacuum suction holes and a backup die that backs up the shell die, wherein the back surface of the shell die and the front surface of the backup die are fitted together to form the same shape, A ventilation groove is machined on the surface of the backup mold or the back surface of the shell mold, leaving a receiving surface for receiving the mating surface; A manufacturing method for a molding die, characterized in that the rear surface of the shell mold or the surface of the backup mold (however, the surface on which the ventilation grooves are machined is referred to as the "receiving surface") is machined with an end mill with a non-flat tip, leaving multiple lines with a feed pitch of 0.5 to 5.0 mm and a machining depth of 0.01 to 0.4 mm, along with ridges between the lines, as machining marks.

[0010] <effect> By cutting the back surface of the shell mold or the surface of the backup mold in one direction with an end mill with a non-flat tip, it is possible to efficiently form multiple lines with a feed pitch of 0.5 to 5.0 mm and a processing depth of 0.01 to 0.4 mm, as well as protrusions between the lines, as cutting marks. [Effects of the Invention]

[0011] According to the molding die of the present invention, the shell mold can be sufficiently backed up by the backup mold, thereby preventing deformation of the shell mold, and all of the vacuum suction holes in the shell mold can be connected to the ventilation grooves, thereby improving the vacuum suction efficiency. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 shows the surface side of the shell mold in the molding die of Example 1, where (a) is a perspective view and (b) is a partially enlarged perspective view. [Figure 2] FIG. 2 shows the rear side of the shell mold, where (a) is a perspective view and (b) is a partially enlarged perspective view. [Figure 3] FIG. 3 shows cutting work, where (a) is a perspective view during rough cutting, (b) is a perspective view during semi-finishing, and (c) is a perspective view during finish cutting. [Figure 4] FIG. 4 shows the front surface side of the backup mold in the molding die of Example 1, where (a) is a perspective view and (b) is a partially enlarged perspective view. [Figure 5] FIG. 5 is a cross-sectional view of the backup type. [Figure 6] FIG. 6 shows the molding die of Example 1 in which the shell die is attached to the backup die, (a) being a perspective view and (b) being a cross-sectional view. [Figure 7] 7(a) is an enlarged cross-sectional view of a main part of the molding die of the comparative example, (b) is an enlarged cross-sectional view of a main part of the molding die of Example 1, and (c) is an enlarged cross-sectional view of a main part of the molding die of Example 1 cut in a different direction. [Figure 8] FIG. 8 is a cross-sectional view of a resin sheet during vacuum forming using the molding die of Example 1. [Figure 9] FIG. 9 is a perspective view showing the front surface side of the backup mold in the molding die of Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0013] <1> Shell type Examples of shell molds include those formed by electroforming, casting, cutting, electrical discharge machining, etc. Those formed by electroforming are preferred because they have advantages such as high manufacturing efficiency, the ability to easily form a concave-convex pattern by transferring it from a model, and the ability to form vacuum suction holes during electroforming. The thickness of the shell mold is not particularly limited, but is preferably 2 to 6 mm, and more preferably 2.5 to 5 mm, because it is easy to manufacture by electroforming or the like, and it is also easy to form vacuum suction holes. The material of the shell mold is not particularly limited, but examples include metals (nickel, steel, etc.) and ceramics.

[0014] By forming a textured pattern on the surface (mold surface) of the shell mold, the textured pattern can be transferred to the surface of the skin that is vacuum-sucked onto the surface of the shell mold. The textured pattern is not particularly limited, but examples include a leather grain pattern, a stitch pattern, and a repeating arrangement of multiple geometric unit patterns.

[0015] The shell mold is preferably attached to the backup mold in a replaceable manner, and examples of the attachment structure include screwing and fitting.

[0016] <2> vacuum suction hole The vacuum suction holes are not particularly limited, but examples include those formed during electroforming by the methods described in JP-A-60-152692, JP-A-9-249987, etc., those formed by mechanical processing (drilling, etc.), and those formed by high-energy beam processing (laser processing, electron beam processing, ion beam processing, etc.). The diameter of the vacuum suction holes is not particularly limited, but is preferably 0.1 to 0.3 mm on the front surface side of the shell mold and 0.1 to 5 mm on the back surface side of the shell mold.

[0017] <3> Backup type The backup mold is not particularly limited, but examples thereof include those formed by casting, cutting, electric discharge machining, and the like. The thickness of the backup mold is not particularly limited, but is preferably 10 mm or more, and more preferably 20 mm or more, because this provides high rigidity. The material of the backup type is not particularly limited, but examples thereof include metals (aluminum alloys, steel, etc.) and ceramics.

[0018] <4> Ventilation groove The ventilation grooves can be formed on either or both of the surface of the backup mold or the back surface of the shell mold. However, it is preferable to form them on only one of them in terms of processing efficiency, etc., and it is more preferable to form them only on the surface of the backup mold in order to reduce the risk of a decrease in mold strength.

[0019] Examples of the ventilation grooves include those formed by machining (cutting, etc.), electrical discharge machining, etching, etc. The pattern of the ventilation grooves is not particularly limited, but examples include one or more lines, a net shape (such as a square lattice shape, a triangular lattice shape, or a hexagonal lattice shape as described in Patent Document 2), and the like. It is preferable that the air grooves extend in a direction intersecting the direction of the creases, because the air grooves communicate with a plurality of the creases.

[0020] The depth of the ventilation groove is not particularly limited, but is preferably 0.2 to 3 mm, more preferably 0.2 to 2 mm, and most preferably 0.3 to 1 mm. If the ventilation groove depth is 0.2 mm or more, the ventilation is good, and if it is 3 mm or less, the strength of the backup mold is less likely to decrease. The width of the ventilation groove (opening width) is not particularly limited, but is preferably 1 to 7 mm, more preferably 1 to 5 mm. If the width of the ventilation groove is 1 mm or more, the ventilation is good, and if it is 7 mm or less, the strength of the backup mold is less likely to decrease.

[0021] <5> Grains and ridges The striations and ridges can be formed on either or both the back surface of the shell mold or the front surface of the backup mold. However, forming them on both reduces the fitting accuracy of the two molds, so it is preferable to form them on only one of them, and it is more preferable to form them only on the back surface of the shell mold, as this reduces the amount of processing required on the shell mold.

[0022] The direction of the creases and ridges may be in one direction over the entire surface on which they are formed (the rear surface of the shell mold or the surface of the backup mold), or the direction may vary among multiple regions set on the surface. The end mill having a non-flat tip is not particularly limited, but examples thereof include a ball end mill and a radius end mill. The blade diameter of the end mill is not particularly limited, but may be 15 to 20 mm, for example.

[0023] As described above, the multiple scores have a feed pitch of 0.5 to 5.0 mm and a processing depth of 0.01 to 0.4 mm, but more preferably a feed pitch of 1.0 to 3.0 mm and a processing depth of 0.02 to 0.15 mm. The relationship between the feed pitch and the processing depth is not particularly limited, but the feed pitch is preferably 20 to 50 times the processing depth.

[0024] <6> mold for molding The molding die of the present invention can be embodied as a die for various molding processes (including, but not limited to, vacuum molding, compressed air molding, insert injection molding, blow molding, stamping molding, press molding, slush molding, etc.) that mold polymeric materials while utilizing a vacuum suction function. [Example]

[0025] Hereinafter, specific examples of the present invention will be described with reference to the drawings. Note that the materials, configurations, and numerical values ​​described in the examples are merely examples and can be changed as appropriate.

[0026] [Example 1] The molding die 1 of Example 1 shown in FIGS. 1 to 8 is a vacuum molding die. The molding die 1 includes a shell mold 2 having a plurality of vacuum suction holes 5 and a backup mold 10 that backs up the shell mold 2, and the back surface of the shell mold and the front surface of the backup mold have the same shape and are fitted together as shown in Figures 6 and 7(b) and (c).

[0027] As shown in Figures 1 and 2, the shell mold 2 is formed into a shell shape with a thickness of 2 to 6 mm by nickel electroforming, and consists of a female (concave) shell main body 3 and a flange portion 4 around the shell main body 3.

[0028] A large number of vacuum suction holes 5 are formed and dispersed throughout the entire shell body 3, and are not formed in the flange 4. The vacuum suction holes 5 are formed during nickel electroforming. The diameter of the vacuum suction holes 5 is 0.1 to 0.3 mm on the front surface of the shell mold 2, and increases toward the back surface, reaching 3 to 5 mm on the back surface of the shell mold 2. The vacuum suction holes may also be formed by post-processing (machining, high-energy beam processing).

[0029] 1, a concave-convex pattern 8 is formed on the surface (mold surface) of the shell main body 3 during electroforming. The concave-convex pattern 8 in the illustrated example is a leather grain pattern.

[0030] As shown in Fig. 2, a plurality of scores 6 with a feed pitch of 0.5 to 5.0 mm and a processing depth of 0.01 to 0.4 mm and ridges 7 between the scores are formed on the back surface of the shell mold 2. These scores 6 and ridges 7 are formed as cutting marks by cutting the back surface of the shell mold 2 with an end mill 20 having a non-flat tip, as shown in Figs. 3(a) and 3(b). The method for this will be described in detail after the backup mold 10 is explained.

[0031] As shown in Figures 4 and 5, the backup mold 10 consists of a backup main body 11 cast from an aluminum alloy to a thickness of 10 to 30 mm, and a box-shaped case 17 that covers the back side of the backup main body with a space between them.

[0032] The surface of the backup main body 11 has a concave shape that is the same as the convex shape of the back surface of the shell main body 3. A temperature control pipe 12 is cast into the back surface of the backup main body 11, and a temperature control fluid can be passed through the temperature control pipe 12. The temperature control pipe 12 is made of, for example, flexible stainless steel pipe.

[0033] On the surface of the backup body 11, ventilation grooves 13 are machined into a rectangular lattice pattern, leaving a receiving surface 14 that receives the back surface of the shell body 3. The ventilation grooves 13 include ventilation grooves that extend parallel to the direction of the striations 6 (FIG. 7(b)) and ventilation grooves that extend in a direction that intersects with the direction of the striations 6 (FIG. 7(c)). For example, the ventilation grooves 13 are 0.2 to 3 mm deep and 1 to 7 mm wide, and the receiving surface 14 is a group of squares measuring 5 mm square to 20 mm square.

[0034] A plurality of ventilation holes 15 are formed in the backup main body 11, which communicate from the ventilation groove 13 to the space on the rear side. The diameter of the ventilation holes 15 is, for example, 5 to 10 mm. The case portion 17 is provided with a vent plug 18 that connects the space to the outside of the mold, so that a vacuum suction device (not shown) outside the mold can be connected.

[0035] As shown in Figure 6, the shell body 3 fits into and abuts against the backup body 11, and the flange 4 fits into the counterbore of the backup body 11 and is fastened with a screw, so that the shell mold 2 is replaceably attached to the backup mold 10. In this attached state, all of the vacuum suction holes 5 communicate with the ventilation grooves 13 via the grooves 6, as shown in Figures 7(b) and (c).

[0036] The molding die 1 configured as above is manufactured by the following method. The rear surface of the shell main body 3 and the front surface of the backup main body 11 must have the same shape for proper fitting, and precision in fitting is ensured by cutting one or both of them.

[0037] To achieve this, the process typically involves three steps: rough machining (see Fig. 3(a)), semi-finishing (see Fig. 3(b)), and finishing (see Fig. 3(c)), ultimately achieving a smooth surface and improving fitting accuracy. Specifically, for example, a ball end mill with a cutting diameter of 16 mm is used, and in rough machining, the feed pitch P1 is set to more than 5.0 mm and the machining depth H1 is set to more than 0.4 mm. In the subsequent semi-finishing machining, the feed pitch P2 is set to 0.5 to 5.0 mm and the machining depth H1 is set to 0.01 to 0.4 mm. In the subsequent finishing machining, the feed pitch P3 is set to less than 0.5 mm and the machining depth H1 is set to less than 0.01 mm. However, when both the back surface of the shell main body 3 and the front surface of the backup main body 11 are subjected to the finishing process (c) to make them nearly smooth, some of the vacuum suction holes 5 are completely blocked by the receiving surface 14 (center of the figure), as shown as a comparative example in Figure 7(a).

[0038] Therefore, in this embodiment, cutting is performed as follows. The surface of the backup main body 11 is subjected to the finishing process shown in FIG. 3(c) to approach a smooth surface. The back surface of the shell body 3 is stopped after rough machining (a) and semi-finishing machining (b), and finish machining (c) is not performed, leaving a plurality of grooves 6 with a feed pitch P2 of 0.5 to 5.0 mm and a machining depth H1 of 0.01 to 0.4 mm, and ridges 7 between the grooves as cutting marks. Even if these cutting marks are left, the required fitting precision is ensured. 7(b) and (c), all the vacuum suction holes 5 communicate with the ventilation grooves 13 via the creases 6, and no vacuum suction holes are completely blocked by the receiving surface 14, thereby improving the suction efficiency in vacuum forming. In particular, as shown in FIG. 7(c), many creases 6 communicate with the ventilation grooves 13 that extend in a direction intersecting the direction of the creases 6.

[0039] Using the molding die 1 configured as above, a resin sheet can be vacuum molded by the following method. As shown in Fig. 8, a thermoplastic resin sheet 21 that has been softened by heating is placed against a molding die 1, and is pressed against the surface of the shell main body 3 by a male die 22. Next, the space inside the backup die 10 is depressurized by the vacuum suction device (not shown) described above, and the resin sheet 21 is vacuum-sucked onto the surface of the shell main body 3 through the vacuum suction holes 5 via the ventilation holes 15, ventilation grooves 13, and grooves 6, thereby forming the resin sheet 21. At this time, due to the high suction efficiency described above, the uneven pattern 8 of the shell main body 3 is faithfully transferred onto the resin sheet 21, and a realistic uneven pattern is formed.

[0040] [Example 2] Next, the molding die of Example 2 shown in Figure 9 differs from Example 1 only in that the ventilation grooves 13 of the backup main body 11 are three linear ventilation grooves 13 extending in a direction intersecting the direction of the creases (see Figure 2), but the rest is the same as Example 1. Each ventilation groove 13 communicates with each ventilation hole 15. 7(c), this ventilation groove 13 also communicates with all the vacuum suction holes 5 via the grooves 6. Therefore, the second embodiment also provides the same effects as the first embodiment.

[0041] The present invention is not limited to the above-described embodiments, and can be embodied by making appropriate modifications within the scope of the invention, for example, as follows. (1) The ventilation groove 13 and the receiving surface 14 may be formed on the rear surface of the shell main body 3. In this case, it is preferable that the ventilation groove and the receiving surface are not formed on the front surface of the backup main body 11. (2) The grooves 6 and ridges 7 may be formed on the receiving surface 14 of the backup main body 11. In this case, it is preferable that the grooves and ridges are not formed on the rear surface of the shell main body 3. [Explanation of symbols]

[0042] 1 Molding mold 2. Shell type 3 Shell body 4 Flange 5 Vacuum suction hole 6 Lines 7 ridges 8 Textured 10 Backup type 11 Backup main unit 12 Temperature control piping 13 Ventilation groove 14 Receiving surface 15 ventilation holes 17 Case part 18 Ventilation plug 20 End Mill 21 Resin sheet 22 male type

Claims

1. A molding die includes a shell mold (2) having a plurality of vacuum suction holes (5) and a backup mold (10) that backs up the shell mold (2), and the back surface of the shell mold (2) and the front surface of the backup mold (10) are fitted together with the same shape, A ventilation groove (13) is formed on the surface of the backup mold (10) or the back surface of the shell mold (2), leaving a receiving surface (14) for receiving the mating surface; A plurality of grooves (6) with a feed pitch of 0.5 to 5.0 mm and a processing depth of 0.01 to 0.4 mm and protrusions (7) between the grooves are formed on the back surface of the shell mold (2) or the surface of the backup mold (10), This molding die is characterized in that the back surface of the shell mold (2) and the surface of the backup mold (10) are in contact with each other at a protrusion (7), and the vacuum suction holes (5) and the ventilation grooves (13) on the back surface side of the shell mold (2) are in communication with each other via grooves (6).

2. 2. A molding die according to claim 1, wherein the ventilation grooves (13) are formed only on the surface of the backup die (10).

3. 3. The molding die according to claim 1, wherein the ventilation grooves (13) include ventilation grooves (13) extending in a direction intersecting the direction of the scores (6).

4. 4. A molding die according to claim 1, 2 or 3, wherein the grooves (6) and the ridges (7) are formed only on the back surface of the shell mold (2).

5. A method for manufacturing a molding die includes a shell die (2) having a plurality of vacuum suction holes (5) and a backup die (10) that backs up the shell die (2), and the back surface of the shell die (2) and the front surface of the backup die (10) are fitted together with the same shape, A ventilation groove (13) is machined on the surface of the backup mold (10) or the back surface of the shell mold (2), leaving a receiving surface (14) for receiving the mating surface; The rear surface of the shell mold (2) or the surface of the backup mold (10) is machined with an end mill (20) having a non-flat tip, leaving a plurality of grooves (6) with a feed pitch of 0.5 to 5.0 mm and a machining depth of 0.01 to 0.4 mm and ridges (7) between the grooves as machining marks; This method for manufacturing a molding die is characterized in that the back surface of the shell die (2) and the surface of the backup die (10) are abutted with a protrusion (7), and the vacuum suction holes (5) and the ventilation grooves (13) on the back surface side of the shell die (2) are connected to each other via grooves (6).

6. 6. The method for manufacturing a molding die according to claim 5, wherein the end mill (20) is a ball end mill or a radius end mill.

7. 7. The method for manufacturing a molding die according to claim 5 or 6, wherein the blade diameter of the end mill (20) is 15 to 20 mm.

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