JP7794072B2 - Vacuum forming method - Google Patents

Description

The present invention relates to a method for vacuum forming a resin sheet.

Vacuum forming is a well-known method for molding automotive parts such as vehicle ceiling panels, in which the object to be molded is pressed against a mold and vacuum-suctioned. Vacuum forming requires the mold to be provided with vacuum holes for vacuum-suctioning the material to be molded, but this leaves marks on the surface of the molded product, which can be unsightly.

Therefore, when transferring a grain pattern to the surface of a material using 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 embedded in the grain pattern and making the vacuum holes less noticeable, thereby improving the appearance of the molded product (see, for example, Patent Document 1).

JP 2015-112868 A

However, with vacuum molding, molding defects can occur due to poor air release 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.

The present invention aims to prevent molding defects from occurring during vacuum molding.

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 placement step of placing the nonwoven fiber sheet on at least a portion of the molding surface of the vacuum mold; an object to be molded placement step of placing the object to be molded on the nonwoven fiber sheet; and a molding step of applying a vacuum to the vacuum holes of the vacuum mold to vacuum-suck the object to be molded onto the molding surface via the nonwoven fiber sheet, thereby forming a molded product, wherein the molding surface has a surface and a plurality of recesses recessed from the surface, the plurality of recesses being arranged independently of one another, and at least some of the vacuum holes being arranged in the recesses; and the fiber sheet placement step involves placing the nonwoven fiber sheet on the surface without placing the nonwoven fiber sheet in the plurality of recesses .

This configuration allows the breathability of the nonwoven fabric fiber sheet to suck air from areas far from the vacuum holes through the vacuum holes, preventing poor air removal. Even if foreign matter adheres to the molding surface, the mesh and flexibility of the nonwoven fabric fiber 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 multiple recesses and the surface to be vacuumed evenly, preventing molding defects when molding uneven molded products.

In the vacuum molding method of the present invention, the molding process may involve 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 recesses to form the object to be molded into the recesses .

This allows the object to be vacuum-adsorbed onto the entire molding surface, effectively preventing molding defects due to insufficient air venting. This also allows the multiple recesses and the surface to be vacuumed evenly, preventing molding defects when molding uneven molded products.

The present invention can reduce the occurrence of molding defects during vacuum molding.

FIG. 2 is a cross-sectional elevation view of a vacuum mold used in the vacuum forming method of the reference example . 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. [0023]FIG. 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. 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 . FIG. 5 is a detailed view of part A shown in FIG. 4. 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. 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. FIG. 8 is a detailed view of part B shown in FIG. 7. 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 . FIG. 2 is a plan view showing a vacuum mold used in the vacuum forming method of the embodiment . 11 is a cross-sectional elevation view of the vacuum mold shown in FIG . 10, taken along the line CC shown in FIG. 12A to 12C are diagrams showing molding steps of a vacuum molding method according to an embodiment using the vacuum mold shown in FIGS. 10 and 11 .

The vacuum molding method of the reference example will be described below with reference to the drawings. First, the vacuum mold 10 used in the vacuum molding method of the reference example will be described with reference to Figure 1. In each drawing, the molding surface 11 will be referred to as the upper side, and the opposite side will be referred to as the lower side.

As shown in FIG. 1, the vacuum mold 10 comprises a molding surface 11, multiple vacuum holes 12, and a manifold 13. The molding surface 11 is the surface that transfers the molding shape to the resin sheet 30, which is the object to be molded, and its surface has the shape of the 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 the nonwoven fiber sheet 20, which is 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 multiple 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).

Next, a vacuum forming method according to a reference example will be described with reference to FIGS.

First, as shown in Figure 2, a fiber sheet placement process is carried out 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 from 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; for example, a thickness of approximately 1 mm may be used.

Next, the molding object placement process 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.

Next, the molding process is carried out. In this 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 is removed from the vacuum holes 12 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.

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, preventing the shape of the molding surface 11 from being transferred to part of the resin sheet 30.

The resin sheet 30 is also flexible and thick enough to absorb the irregularities of foreign matter 50 that adheres to the molding surface 11 due to deformation. Therefore, when a foreign matter 50 is present on the molding surface 11, the lower surface 25 that contacts the molding surface 11 deforms as shown in Figure 5, absorbing the irregularities of the foreign matter 50. This prevents the irregularities of the foreign matter 50 from being transferred to the resin sheet 30, thereby preventing molding defects.

When the molding process is complete, the resin sheet 30 shown in Figure 5 is molded into the molded product 35 shown in Figure 6.

Next, the molded product removal process is carried out. 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 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 below. This causes the molded product 35 to peel off from the nonwoven fabric sheet 20 attached to the molding surface 11, as indicated by the arrow 93 in FIG. 7, allowing the molded product 35 to 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.

As described above, the vacuum molding method of the reference example can suppress the occurrence of molding defects during vacuum molding by attaching a breathable and flexible nonwoven fiber sheet 20 to the molding surface 11 of the vacuum mold 10, placing a resin sheet 30 on top of that, and then performing vacuum molding.

Next, a vacuum molding method for an embodiment of a resin sheet 30 using a vacuum mold 60 will be described with reference to Figures 10 to 12. As shown in Figures 10 and 11, a molding surface 63 of the 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.

When vacuum molding is performed using this vacuum mold 60, as shown in Figure 12, a nonwoven fiber sheet 20 is attached to the surface 61 that protrudes into the recess 62. At this time, the nonwoven fiber sheet 20 is not attached to the recess 62. Then, as previously explained with reference to Figure 4, a heated and softened resin sheet 30 is placed on top of the nonwoven fiber sheet 20 attached to the surface 61, and the vacuum holes 64 are evacuated as indicated by the hollow arrows 71 in Figure 12. This creates a vacuum in the recess 62, and the surface 61 that is connected to the recess 62 due to the breathability of the nonwoven fiber sheet 20 also creates a vacuum, and the shape of the molding surface 63 consisting of the surface 61 and the recess 62 is transferred to the resin sheet 30.

In this way, the multiple recesses 62 and the surface 61 can be uniformly evacuated, thereby reducing molding defects when molding an uneven molded product 35.

In the above explanation, the object to be molded is described as a resin sheet 30, but this is not limited to this and it could also be, for example, a metal sheet or a paper sheet.

10, 60 Vacuum mold, 11, 63 Molding surface, 12, 64 Vacuum hole, 13 Manifold, 20 Nonwoven fiber sheet, 25 Underside, 30 Resin sheet, 35 Molded product, 40 Clamp, 50 Foreign matter, 61 Surface, 62 Recess.

Claims (2)

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 : 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: