Vacuum forming method

Abstract

To suppress occurrence of molding defects in vacuum molding.SOLUTION: A vacuum molding method comprises: a step of preparing a vacuum mold 10 having a molding surface 11 for molding a resin sheet 30 and a plurality of vacuum holes 12, and a nonwoven fabric fiber sheet 20 with breathability and flexibility; a fiber sheet placement step of placing the nonwoven fabric fiber sheet 20 on the molding surface 11 of the vacuum mold 10; resin sheet 30 placement step of placing the resin sheet 30 on the nonwoven fabric fiber sheet 20; and a molding step of evacuating the vacuum holes 12 of the vacuum mold 10 and vacuum-sucking the resin sheet 30 onto the molding surface 11 via the nonwoven fabric fiber sheet 20 to mold it into a molded article.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for vacuum forming a resin sheet. [Background technology]

[0002] Vacuum molding is a well-known method for molding automobile-related parts such as vehicle ceiling panels, in which the object to be molded is pressed against a mold and vacuum-suctioned. Vacuum molding requires the creation of vacuum holes in the mold to suck the material to be molded, but this leaves traces of the vacuum holes on the surface of the molded product, which can lead to a poor appearance.

[0003] Therefore, when transferring a grain pattern onto the surface of a material by vacuum molding, a method has been proposed in which multiple vacuum holes are irregularly arranged within the grain pattern area, making the vacuum hole traces less noticeable by burying them in the grain pattern, thereby improving the appearance of the molded product (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-112868 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in vacuum molding, molding defects can occur due to poor air removal in areas away from the vacuum holes, or if foreign matter is attached to the molding surface, the shape of the foreign matter can be transferred to the molded product.

[0006] Therefore, an object of the present invention is to suppress the occurrence of molding defects in vacuum molding. [Means for solving the problem]

[0007] The vacuum molding method of the present invention includes the steps of: preparing a vacuum mold having a molding surface for molding an object to be molded and a plurality of vacuum holes provided on the molding surface for vacuum-sucking the object to be molded onto the molding surface; and a breathable and flexible nonwoven fiber sheet; a fiber sheet arrangement step of arranging the nonwoven fiber sheet on at least a portion of the molding surface of the vacuum mold; an object to be molded arrangement step of arranging the object to be molded on the nonwoven fiber sheet; and a molding step of vacuum-sucking the object to be molded onto the molding surface via the nonwoven fiber sheet by applying a vacuum to the vacuum holes of the vacuum mold, thereby forming a molded product. A vacuum molding method, wherein the molding surface has a surface and a plurality of recesses recessed from the surface, the plurality of recesses are arranged independently of one another, and at least some of the vacuum holes are arranged in the recesses, and the fiber sheet arranging step arranges the nonwoven fiber sheet on the surface without arranging the nonwoven fiber sheet in the plurality of recesses. It is characterized by the following.

[0008] This configuration allows the breathability of the nonwoven fabric sheet to suck air away from the vacuum holes, preventing poor air removal. Even if foreign matter is attached to the molding surface, the mesh and flexibility of the nonwoven fabric sheet can absorb the irregularities of the foreign matter, preventing the shape of the foreign matter from being transferred to the molded product. This reduces molding defects during vacuum molding. This also allows the plurality of recesses and the surface to be evacuated evenly, making it possible to prevent molding defects when molding an uneven molded product.

[0009] In the vacuum forming method of the present invention, the forming step includes applying a vacuum to the vacuum holes to form the nonwoven fiber sheet. surface The object to be molded is placed on the nonwoven fabric fiber sheet through the vacuum layer. surface Vacuum adsorption At the same time, the vacuum hole is evacuated to create a vacuum in the recess, and the molding object is vacuum-adsorbed into the recess. It may also be molded.

[0010] This allows the object to be vacuum-sucked onto the entire molding surface, and molding defects due to insufficient air evacuation can be more effectively prevented. This also allows the plurality of recesses and the surface to be evacuated evenly, making it possible to prevent molding defects when molding an uneven molded product. [Effects of the Invention]

[0015] The present invention can suppress the occurrence of molding defects in vacuum molding. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a cross-sectional elevation view of a vacuum mold used in the vacuum forming method of the reference example. [Figure 2] 2 is a cross-sectional elevation view showing a fiber sheet placement step of attaching a nonwoven fiber sheet to the molding surface of the vacuum mold shown in FIG. 1. FIG. [Figure 3] 3 is a cross-sectional elevation view showing a state in which a heated resin sheet is placed on the nonwoven fiber sheet shown in FIG. 2 and the outer periphery is clamped. FIG. [Figure 4] FIG. 4 is a cross-sectional elevation view showing a molding step in which a vacuum is applied to the vacuum holes to vacuum-suck the resin sheet onto the molding surface in the state shown in FIG. 3. [Figure 5] FIG. 5 is a detailed view of part A shown in FIG. [Figure 6] 1 is a cross-sectional elevation view showing a state in which the resin sheet has been molded into a molded product after the molding process of the resin sheet is completed. FIG. [Figure 7] FIG. 10 is a cross-sectional elevation view showing a state in which air is introduced into a vacuum hole to push up the molded product during the molded product removal process. [Figure 8] FIG. 8 is a detailed view of part B shown in FIG. [Figure 9] FIG. 8 is a cross-sectional elevation view showing a state in which the molded product has been removed after the state shown in FIG. 7. [Figure 10] FIG. 2 is a plan view showing a vacuum mold used in the vacuum forming method of the embodiment. [Figure 11] 11 is a cross-sectional elevation view of the vacuum mold shown in FIG. 10, taken along the CC cross section shown in FIG. [Figure 12] 12A to 12C are diagrams showing molding steps of a vacuum molding method according to an embodiment using the vacuum mold shown in FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0017] With reference to the drawings below, Reference example First, let us explain the vacuum forming method using Figure 1. Reference example The vacuum mold 10 used in the vacuum molding method will be described below. In each drawing, the molding surface 11 will be referred to as the upper side, and the opposite side as the lower side.

[0018] As shown in FIG. 1, the vacuum mold 10 includes a molding surface 11, a plurality of vacuum holes 12, and a manifold 13. The molding surface 11 is a surface that transfers a molding shape to a resin sheet 30, which is an object to be molded, and its surface has the shape of a molded product 35. Each vacuum hole 12 is provided on the molding surface 11 and vacuum-adsorbs the resin sheet 30 placed on the molding surface 11 to the molding surface 11. The vacuum holes 12 have a small diameter so that a nonwoven fiber sheet 20, which will be attached to the molding surface 11 (described later), is not drawn in. The diameter of each vacuum hole 12 may be, for example, approximately 0.5 mm to 1 mm. A manifold 13 that communicates with the plurality of vacuum holes 12 is provided inside the vacuum mold 10. The manifold 13 is connected to a vacuum device (not shown) and a compressed air supply device (not shown).

[0019] Next, referring to Figures 2 to 9, Reference example The vacuum forming method will be explained.

[0020] First, as shown in Figure 2, a fiber sheet placement step is performed in which a nonwoven fiber sheet 20 is placed and attached onto the molding surface 11. Here, the nonwoven fiber sheet 20 is a breathable and flexible nonwoven fabric, for example, a nonwoven fabric made of resin fibers such as polyester. The thickness of the nonwoven fiber sheet 20 can be freely selected, but as will be explained later, it should be thick enough to absorb the irregularities of foreign matter 50 (see Figure 5) that has adhered to the molding surface 11 due to deformation, and may be, for example, about 1 mm.

[0021] Next, the molding object placement step is carried out. As shown in Figure 3, the heated and softened resin sheet 30 is placed on top of the nonwoven fabric fiber sheet 20 attached to the molding surface 11. Then, the outer periphery of the resin sheet 30 is fixed to the molding surface 11 with clamps 40. In this state, a gap is left between the nonwoven fabric fiber sheet 20 attached to the molding surface 11 and the resin sheet 30.

[0022] Next, the molding process is performed. In the molding process, as indicated by the open arrow 81 in FIG. 4, a vacuum device (not shown) removes air from the manifold 13, creating a vacuum in the manifold 13. This removes air from the vacuum holes 12, creating a vacuum in the vacuum holes 12, as indicated by the open arrow 82 in FIG. 4. The nonwoven fabric fiber sheet 20 is breathable and communicates with the vacuum holes 12. Therefore, when the air in the vacuum holes 12 is removed as indicated by the open arrow 84 in FIG. 5, the air contained in the nonwoven fabric fiber sheet 20 around the vacuum holes 12 is drawn into the vacuum holes 12 through the nonwoven fabric fiber sheet 20, as indicated by arrows 85 and 86 in FIG. 5. This causes the nonwoven fabric fiber sheet 20 to form a vacuum layer that extends across the entire molding surface 11. The resin sheet 30 is then vacuum-adsorbed to the molding surface 11 via the vacuum layer of the nonwoven fabric fiber sheet 20, as indicated by the arrow 83 in FIG. 4. This transfers the shape of the molding surface 11 to the resin sheet 30.

[0023] In this way, the breathability of the nonwoven fiber sheet 20 allows air in areas away from the vacuum holes 12 to be sucked through the vacuum holes 12, forming a vacuum layer between the molding surface 11 and the resin sheet 30, thereby preventing poor air removal between the molding surface 11 and the resin sheet 30. This prevents molding defects in which air remains between the molding surface 11 and the resin sheet 30 and the shape of the molding surface 11 is not transferred to part of the resin sheet 30.

[0024] Furthermore, resin sheet 30 is flexible and has a thickness that allows it to absorb the irregularities of foreign matter 50 that has adhered to molding surface 11 due to deformation. Therefore, when foreign matter 50 is present on molding surface 11, lower surface 25 that contacts molding surface 11 deforms to absorb the irregularities of foreign matter 50, as shown in Figure 5. This prevents the irregularities of foreign matter 50 from being transferred to resin sheet 30, thereby preventing molding defects.

[0025] When the molding process is completed, the resin sheet 30 shown in FIG. 5 is molded into a molded product 35 shown in FIG.

[0026] Next, the molded product removal process is performed. The manifold 13 is connected to a compressed air supply device (not shown), and air is introduced into the manifold 13 as indicated by the open arrow 91 in FIG. 7. The air that has entered the manifold 13 flows from the manifold 13 into the vacuum hole 12 as indicated by the open arrow 92 in FIG. 7. The air that has entered the vacuum hole 12 as indicated by the open arrow 94 in FIG. 8 flows through the nonwoven fabric fiber sheet 20 as indicated by arrows 95 and 96 in FIG. 8 and is blown toward the molded product 35 as indicated by the open arrow 97 in FIG. 8, pushing the molded product 35 upward from its bottom surface. As a result, the molded product 35 peels off from the nonwoven fabric fiber sheet 20 attached to the molding surface 11 as indicated by the arrow 93 in FIG. 7, and the molded product 35 can be removed from the vacuum mold 10. The molded product removal process is then completed by removing the molded product 35 as shown in FIG. 9. This allows the molded product 35 to be easily removed from the vacuum mold 10 after molding.

[0027] As explained above, Reference example In this vacuum molding method, a breathable and flexible nonwoven fiber sheet 20 is attached to the molding surface 11 of the vacuum mold 10, and a resin sheet 30 is placed on top of that to perform vacuum molding, thereby preventing molding defects from occurring during vacuum molding.

[0028] Next, while referring to Figures 10 to 12, Ramen Resin sheet 30 using hollow mold 60 In an embodiment The vacuum molding method will now be described. As shown in Figures 10 and 11, the molding surface 63 of a vacuum mold 60 is composed of a surface 61 and a plurality of recesses 62 recessed from the surface 61. The recesses 62 are arranged independently of one another, and a plurality of vacuum holes 64 are arranged in the recesses 62. The surface 61 forms convex portions that protrude relative to the recesses 62.

[0029] When vacuum molding is performed using this vacuum mold 60, as shown in Figure 12, the nonwoven fabric fiber sheet 20 is attached to the surface 61 that protrudes into the recesses 62. At this time, the nonwoven fabric fiber sheet 20 is not attached to the recesses 62. Then, as previously described with reference to Figure 4, the heated and softened resin sheet 30 is placed on top of the nonwoven fabric fiber sheet 20 attached to the surface 61, and the vacuum holes 64 are evacuated as indicated by the outline arrows 71 in Figure 12. As a result, the recesses 62 are evacuated, and the surface 61 that communicates with the recesses 62 is also evacuated due to the breathability of the nonwoven fabric fiber sheet 20, and the shape of the molding surface 63 composed of the surface 61 and the recesses 62 is transferred to the resin sheet 30.

[0030] In this way, the plurality of recesses 62 and the surface 61 can be evacuated uniformly, and molding defects can be suppressed when molding a molded product 35 having irregularities.

[0031] In the above description, the molding object is described as the resin sheet 30, but it is not limited to this and may be, for example, a metal sheet or a paper sheet. [Explanation of symbols]

[0032] 10, 60 vacuum mold, 11, 63 molding surface, 12, 64 vacuum hole, 13 manifold, 20 nonwoven fiber sheet, 25 lower surface, 30 resin sheet, 35 molding, 40 clamp, 50 foreign matter, 61 surface, 62 recess.

Claims

1. a vacuum mold having a molding surface for molding an object to be molded and a plurality of vacuum holes provided on the molding surface for vacuum-sucking the object to be molded onto the molding surface; Providing a breathable and flexible nonwoven fiber sheet; a fiber sheet placement step of placing the nonwoven fiber sheet on at least a portion of the molding surface of the vacuum mold; a molding object placement step of placing the molding object on the nonwoven fabric fiber sheet; a molding step of vacuuming the vacuum holes of the vacuum mold to vacuum-adsorb the object to the molding surface via the nonwoven fabric fiber sheet, thereby forming a molded product, the molding surface has a surface and a plurality of recesses recessed from the surface, The plurality of recesses are arranged independently of each other, and at least some of the vacuum holes are arranged in the recesses; In the fiber sheet arranging step, the nonwoven fabric fiber sheet is not arranged in the plurality of recesses, but the nonwoven fabric fiber sheet is arranged on the surface. A vacuum forming method characterized by:

2. The vacuum forming method according to claim 1, The molding step includes evacuating the vacuum holes to form a vacuum layer that spreads over the surface of the nonwoven fabric fiber sheet, vacuum-adsorbing the object to be molded onto the surface via the nonwoven fabric fiber sheet that has become a vacuum layer, and vacuum-adsorbing the object to be molded onto the recess by vacuum-adsorbing the object to be molded into the recess, A vacuum forming method characterized by:

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