Abstract:
A method for manufacturing an automotive resin part includes: heating a fiber reinforced plastic material that uses a thermoplastic resin as a binder resin and arranging the fiber reinforced plastic material between a first die having a projected section for molding and a second die having a recessed section for molding that corresponds to the projected section; approaching the first die and the second die in a molding direction and holding the fiber reinforced plastic material by the projected section and a movable pad provided in the recessed section; and stacking the first die and the second die in the molding direction and press-molding the fiber reinforced plastic material while a state that the fiber reinforced resin material is held between the projected section and the movable pad is maintained by moving the movable pad along with movement of the projected section in the molding direction.

Description:
INCORPORATION BY REFERENCE 
       [0001]    The disclosure of Japanese Patent Application No. 2014-116171 filed on Jun. 4, 2014 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a method for manufacturing an automotive resin part and a manufacturing device of an automotive resin part. 
         [0004]    2. Description of Related Art 
         [0005]    For a purpose of cost reduction and productivity improvement, it has been considered to switch a binder resin of a fiber reinforced plastic (FRP) from a thermosetting resin to a thermoplastic resin. Stamping molding is adopted as a method for molding the FRP that uses this thermoplastic resin. A molding die that is used for the stamping molding is disclosed in Japanese Patent Application Publication No. 7-256768 (JP 7-256768 A), for example. 
         [0006]    However, in the case of the FRP that uses the thermoplastic resin as the binder resin, fluidity of the resin and the fiber is low during molding. Accordingly, occurrence of phenomena such as underfill, thickness reduction, fiber unfilled, and the fiber having directivity during deep drawing by the conventional stamping molding has been concerned. In addition, the above-described conventional molding die is used for molding of preform for an FRP product, and a further additional process is required to obtain a resin part in a final shape. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention provides a method for manufacturing an automotive resin part and a manufacturing device of an automotive resin part that suppress reduction in strength during deep drawing by stamping molding, regarding an FRP that uses a thermoplastic resin as a binder resin. 
         [0008]    A first aspect of the invention relates to a method for manufacturing an automotive resin part. The method for manufacturing an automotive resin part includes: heating a fiber reinforced plastic material that uses a thermoplastic resin as a binder resin and arranging the fiber reinforced plastic material between a first die that has a projected section for molding and a second die that has a recessed section for molding that corresponds to the projected section; approaching the first die and the second die in a molding direction and holding the fiber reinforced plastic material by the projected section and a movable pad that is provided in the recessed section; and stacking the first die and the second die in the molding direction and press-molding the fiber reinforced plastic material while a state that the fiber reinforced resin material is held between the projected section and the movable pad is maintained by moving the movable pad along with movement of the projected section in the molding direction. 
         [0009]    In this method for manufacturing an automotive resin part, the molding of the fiber reinforced plastic material of fiber reinforced plastic (FRP) progresses in a state that a portion of the fiber reinforced plastic material is held between the projected section of the first die and the movable pad of the second die. The fiber reinforced plastic material is drawn into the die without being stretched to a great degree. Accordingly, the fiber reinforced plastic material is molded while the resin and the fiber of the fiber reinforced plastic material remain to be mixed, so as to suppress underfill. In addition, the fiber is filled in the resin without having directivity. Thus, regarding the FRP that uses the thermoplastic resin as the binder resin, it is possible to suppress reduction in strength during deep drawing by stamping molding. 
         [0010]    As described above, according to the above aspect, such an excellent effect that the reduction in strength during the deep drawing by the stamping molding can be suppressed regarding the FRP that uses the thermoplastic resin as the binder resin can be obtained. 
         [0011]    In the above aspect, a tip of the movable pad may be located at a position where the fiber reinforced plastic material is arranged when press molding is initiated, and may move to a die surface at a bottom of the recessed section when the press molding is finished. 
         [0012]    In this method for manufacturing an automotive resin part, the tip of the movable pad moves from the position where the fiber reinforced plastic material is arranged to the die surface at the bottom of the recessed section during the press molding. Thus, the fiber reinforced plastic material can be molded in a final shape by single pressing. 
         [0013]    According to the above aspect, such an excellent effect that the fiber reinforced plastic material can be molded into the final shape by the single pressing can be obtained. 
         [0014]    In the above aspect, the state that the fiber reinforced plastic material is held between the projected section and the movable pad may continue until the press molding is finished. 
         [0015]    In this method for manufacturing an automotive resin part, the state that the fiber reinforced plastic material is held between the projected section and the movable pad continues until the press molding is finished. Thus, it is possible to draw the fiber reinforced plastic material into each portion of the die while suppressing a portion of the fiber reinforced plastic material that is held between the projected section and the movable pad from being stretched. In addition, since both surfaces of the fiber reinforced plastic material can be cooled by the projected section and the movable pad, deformation of a product after the molding can be suppressed. 
         [0016]    According to the above aspect, such excellent effects that the fiber reinforced plastic material can be drawn into each of the portions of the die while the portion of the fiber reinforced plastic material that is held between the projected section and the movable pad is suppressed from being stretched and that the deformation of the product after the molding can be suppressed can be obtained. 
         [0017]    In the above aspect, when the fiber reinforced plastic material is held between the projected section and the movable pad, at least one of the projected section and the movable pad may bite into the fiber reinforced plastic material. 
         [0018]    In this method for manufacturing an automotive resin part, at least one of the projected section and the movable pad bites into the fiber reinforced plastic material. Thus, the fiber reinforced plastic material can further be suppressed from being stretched during the molding. 
         [0019]    According to the above aspect, such an excellent effect that the fiber reinforced plastic material can further be suppressed from being stretched during the molding can be obtained. 
         [0020]    A second aspect of the invention relates to a manufacturing device of an automotive resin part. The manufacturing device of an automotive resin part has: a first die that has a projected section for molding; a second die that has a recessed section for molding that corresponds to the projected section; and a movable pad that is provided in the recessed section, moves along with movement of the projected section in a molding direction, and is configured to hold a fiber reinforced plastic material between the projected section and the movable pad. 
         [0021]    In this manufacturing device of an automotive resin part, molding can progress in a state that a portion of the fiber reinforced plastic material is held between the projected section of the first die and the movable pad of the second die. The fiber reinforced plastic material is drawn into the die without being stretched to a great degree. Accordingly, the fiber reinforced plastic material is molded while the resin and the fiber of the fiber reinforced plastic material remain to be mixed, so as to suppress underfill. In addition, the fiber is filled in the resin without having directivity. Thus, regarding the FRP that uses the thermoplastic resin as the binder resin, it is possible to suppress reduction in strength during deep drawing by stamping molding and to obtain a resin part in a final shape by single molding. 
         [0022]    According to the above aspect, such excellent effects that the reduction in strength during the deep drawing by the stamping molding can be suppressed regarding the FRP that uses the thermoplastic resin as the binder resin and that the resin part in the final shape can be obtained by the single molding can be obtained. 
         [0023]    In the above aspect, a tip of the movable pad may be configured to be located at a position where the fiber reinforced plastic material is arranged when press molding is initiated, and move to a die surface at a bottom of the recessed section when the press molding is finished. 
         [0024]    In this manufacturing device of an automotive resin part, the tip of the movable pad moves from the position where the fiber reinforced plastic material is arranged to the die surface at the bottom of the recessed section. Thus, the fiber reinforced plastic material can be molded into the final shape by single pressing. 
         [0025]    According to the above aspect, such an excellent effect that the fiber reinforced plastic material can be molded in the final shape by the single pressing can be obtained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
           [0027]      FIG. 1A  is a cross-sectional view of a state that an upper die and a lower die are separated to be opened; 
           [0028]      FIG. 1B  is a cross-sectional view of a state that a fiber reinforced plastic material is placed on the lower die; 
           [0029]      FIG. 1C  is a cross-sectional view of a state that the fiber reinforced plastic material is held between a projected section and a movable pad; 
           [0030]      FIG. 1D  is a cross-sectional view of a state in the middle of pressing; 
           [0031]      FIG. 1E  is a cross-sectional view of a completed state of pressing; 
           [0032]      FIG. 2  is a partially enlarged cross-sectional view of a state that the projected section is biting into the fiber reinforced plastic material; and 
           [0033]      FIG. 3  is a perspective view of a shape of a product. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0034]    A description will hereinafter be made on an embodiment of the invention on the basis of the drawings. 
         [0035]    [Manufacturing Device of Automotive Resin Part] 
         [0036]    In  FIG. 1A , a manufacturing device of an automotive resin part  10  according to this embodiment has an upper die  11  as an example of the first die, a lower die  12  as an example of the second die, and a movable pad  14 . 
         [0037]    The upper die  11  is a die that has a projected section  16  for molding, and is configured to be movable in a molding direction (an arrow D direction) and a die opening direction (an arrow U direction). The projected section  16  is formed to be projected downward from a base section  18  to have a generally trapezoidal cross section, for example. A side wall section  20  of the projected section  16  is provided with a die releasing gradient. 
         [0038]    The lower die  12  is a die that has a recessed section  22  for molding that corresponds to the projected section  16 , and is fixed to an unillustrated seat. The recessed section  22  is provided to be recessed downward from a base section  28 . A side wall section  24  of the recessed section  22  is also provided with a die releasing gradient that is similar to the side wall section  20  of the projected section  16 . Shapes of the projected section  16  and the recessed section  22  are appropriately determined in accordance with an automotive resin part  40  that is molded by the upper die  11  and the lower die  12  ( FIG. 1E ,  FIG. 3 ). 
         [0039]    The movable pad  14  is a member that is provided in the recessed section  22 , and is constructed of a similar material as that of the lower die  12 , for example. The movable pad  14  moves along movement of the projected section  16  in the molding direction, and can hold a fiber reinforced plastic material  30  between the movable pad  14  and the projected section  16 . More specifically, a guide section  26  that extends in the molding direction is provided in the lower die  12 . This guide section  26  may be located on the inside or outside of the lower die  12 . As shown in  FIGS. 1B to 1E , the movable pad  14  is configured to be movable in the molding direction along the guide section  26 . 
         [0040]    The fiber reinforced plastic material  30  is formed by forming fiber reinforced plastic (FRP) that uses a thermoplastic resin as a binder resin into a sheet shape. As the fiber reinforced plastic material  30 , carbon fiber reinforced plastic (CFRP) can be used. 
         [0041]    A reaction force generation section  32  for applying a reaction force against the projected section  16  to the movable pad  14  is provided between the movable pad  14  and the lower die  12 . It is possible by applying the reaction force to the movable pad  14  to hold the fiber reinforced plastic material  30  between the projected section  16  and the movable pad  14  and to mold said fiber reinforced plastic material  30  to have a final shape. As the reaction force generation section  32 , a compression spring, a gas spring, a hydraulic/pneumatic equipment, a linear driving mechanism, or the like can be used. In addition, the reaction force may be applied to said movable pad  14  by controlling movement of the movable pad  14 . 
         [0042]    As shown in  FIGS. 1A ,  1 B, a tip of the movable pad  14  is configured to be located at a position where the fiber reinforced plastic material  30  is arranged when press molding is initiated. More specifically, the tip of the movable pad  14  is at a same height as the base section  28  of the lower die  12 , and is in a contact state with a lower surface of the fiber reinforced plastic material  30 . Noted that the tip of the movable pad  14  may be at a slightly higher position than the base section  28  of the lower die  12  in a state before initiation of the press molding that the fiber reinforced plastic material  30  ( FIG. 1B ) is not arranged on the lower die  12 . In this case, when the fiber reinforced plastic material  30  is arranged, the movable pad  14  moves downward by a weight of said fiber reinforced plastic material  30 , and the tip of the movable pad  14  is located at the same height as the base section  28  of the lower die  12 . 
         [0043]    As shown in  FIG. 1E , the tip of the movable pad  14  is configured to move to a die surface at a bottom of the recessed section  22  when the press molding is finished. Then, at this time, the tip of the movable pad  14  constitutes a portion of the die surface of the lower die  12 , that is, a portion of the bottom of the recessed section  22 . Noted that the tip of the movable pad  14  may constitute the entire bottom of the recessed section  22 . 
         [0044]    Noted that, as shown in  FIG. 3 , in the case where the automotive resin part  40  is a long part, the movable pad  14  may be configured to be long in accordance with the automotive resin part  40 . In addition, the plural movable pads  14  may be used in parallel, so as to correspond to the long part. 
       (Action) 
       [0045]    This embodiment is configured as described above, and an action thereof will hereinafter be described. In  FIGS. 1A to 1E , in the manufacturing device of an automotive resin part  10  according to this embodiment, the automotive resin part  40  ( FIG. 3 ) can be manufactured by stamping molding by using a following manufacturing method. 
       [Method for Manufacturing Automotive Resin Part] 
       [0046]    In  FIGS. 1A to 1E , a method for manufacturing an automotive resin part according to this embodiment has a first process S 1 , a second process S 2 , and a third process S 3 .  FIG. 1A  shows a state that the upper die  11  and the lower die  12  are separated and opened. 
         [0047]    In  FIG. 1B , in the first process S 1 , the fiber reinforced plastic material  30  that uses the thermoplastic resin as the binder resin is heated and arranged between the upper die  11  (the first die) that has the projected section  16  for molding and the lower die  12  (the second die) that has the recessed section  22  for molding that corresponds to the projected section  16 . 
         [0048]    In  FIG. 1C , in the second process S 2 , the upper die  11  and the lower die  12  are approached in the molding direction, and the fiber reinforced plastic material  30  is held between the projected section  16  and the movable pad  14  that is provided in the recessed section  22 . At this time, as shown in  FIG. 2 , at least one of the projected section  16  and the movable pad  14  bites into the fiber reinforced plastic material  30 . This state continues until the press molding is finished. Noted that, in an illustrated example, a width of a tip of the projected section  16  is smaller than a width of the tip of the movable pad  14 . Accordingly, the projected section  16  bites into the fiber reinforced plastic material  30 . 
         [0049]    In  FIGS. 1D ,  1 E, in the third process S 3 , the movable pad  14  moves along with the movement of the projected section  16  in the molding direction. In this way, while a state that the fiber reinforced plastic material  30  is held between the projected section  16  and the movable pad  14  is maintained, the upper die  11  and the lower die  12  are stacked in the molding direction to press-mold the fiber reinforced plastic material  30 . In the case where the reaction force generation section  32  is the compression spring, the gas spring, or the like that is deformed or displaced by an external force, the movable pad  14  moves by following the movement of the projected section  16  in the molding direction. At this time, as described above, at least one of the projected section  16  and the movable pad  14  bites into the fiber reinforced plastic material  30 , and a portion of said fiber reinforced plastic material  30  that is held between the projected section  16  and the movable pad  14  is compressed to a greater degree than a portion of said fiber reinforced plastic material  30  that is not held between the projected section  16  and the movable pad  14  in a thickness direction of the fiber reinforced plastic material  30 . In this state, the upper die  11  and the lower die  12  are stacked in the molding direction. 
         [0050]    In this method for manufacturing an automotive resin part, the molding of the fiber reinforced plastic material  30  of the fiber reinforced plastic (FRP) progresses in a state that the portion of the fiber reinforced plastic material  30  is held between the projected section  16  of the upper die  11  and the movable pad  14  of the lower die  12 . The fiber reinforced plastic material  30  is drawn into the die without being stretched to a great degree. Accordingly, the fiber reinforced plastic material  30  is molded while the resin and the fiber thereof remain to be mixed, so as to prevent underfill. In addition, the fiber is filled in the resin without having directivity. Thus, regarding the FRP that uses the thermoplastic resin as the binder resin, it is possible to suppress reduction in strength during deep drawing by the stamping molding. By performing the deep drawing, a part with bending rigidity can be developed. 
         [0051]    In addition, the tip of the movable pad  14  is located at the position where the fiber reinforced plastic material  30  is arranged when the press molding is initiated. Then, the tip of the movable pad  14  moves to the mold surface at the bottom of the recessed section  22  when the press molding is finished. Thus, the fiber reinforced plastic material  30  can be molded into the final shape by the single pressing. Therefore, cost reduction and productivity improvement are possible. 
         [0052]    The state that the fiber reinforced plastic material  30  is held between the projected section  16  and the movable pad  14  continues until the press molding is finished. More specifically, the reaction force generation section  32  applies the reaction force to the movable pad  14  against a pressing force of the projected section  16 . Accordingly, the fiber reinforced plastic material  30  can be held between the projected section  16  and the movable pad  14 , and said fiber reinforced plastic material  30  can be molded into the final shape. At this time, since at least one of the projected section  16  and the movable pad  14  bites into the fiber reinforced plastic material  30 , it is possible to draw the fiber reinforced plastic material  30  into each portion of the die while suppressing the portion of the fiber reinforced plastic material  30  that is held between the projected section  16  and the movable pad  14  from being stretched. In addition, since both surfaces of the fiber reinforced plastic material  30  can be cooled by the projected section  16  and the movable pad  14 , deformation of a product after the molding can be suppressed. 
         [0053]    Furthermore, the upper die  11  and the lower die  12  separate from each other, and the automotive resin part  40  is pushed out when the movable pad  14  is returned to an original position. Thus, a die releasing property becomes favorable. 
         [0054]    Noted that, due to a slight gap between the movable pad  14  and the recessed section  22  during the press molding or due to a difference in a cooling speed with respect to the fiber reinforced plastic material  30  between the movable pad  14  and the recessed section  22 , a boundary line  42  is clearly formed in the molded automotive resin part  40  ( FIG. 3 ). This boundary line  42  is formed by an aspect such as a difference in coloration, a striped projection, or a burr. 
       Another Embodiment 
       [0055]    The example of the embodiment of the invention has been described so far. However, the embodiment of the invention is not limited to the above, and it is needless to say that, in addition to the above, various modifications can be made to the invention within the scope of the gist thereof for implementation. 
         [0056]    For example, the upper die  11  is used as the first die, and the lower mold  12  is used as the second die. However, the lower die may be used as the first die, and the upper die may be used as the second die. In addition, the tip of the movable pad  14  moves to the die surface of the bottom of the recessed section  22  when the press molding is finished. However, displacement of the tip of the movable pad  14  can appropriately be changed in accordance with a product shape. Furthermore, the state that the fiber reinforced plastic material  30  is held between the projected section  16  and the movable pad  14  continues until the press molding is finished. However, the movable pad  14  may be separated from the fiber reinforced plastic material  30  before the press molding is finished as long as there is no problem with strength or finishing of the product. 
         [0057]    The second process S 2  and the third process S 3  do not always have to be separate processes but may be combined into one process.