Abstract:
A process for manufacturing a preform, and apparatus therefor, wherein a preform with a branched portion in its cross-section profile is continuously manufactured by delivering a raw form of reinforcing fiber base material with a branched portion in its cross-section profile, among multiple reinforcing fiber base materials for constructing the preform, intermittently in the longitudinal direction thereof; at each delivery discontinuation, performing heat and/or pressure application to the raw base material so as to tentatively obtain a preliminary shaped matter with given configuration; and uniting the obtained preliminary shaped matter with given configuration with raw forms of other reinforcing fiber base materials for constructing the preform.

Description:
This is a U.S. National Phase application of application number PCT/JP2007/055195, filed Mar. 15, 2007 (which is incorporated herein by reference in its entirety), which claims priority benefit of JP 2006-070777 filed Mar. 15, 2006. 
     FIELD OF THE INVENTION 
     The present invention relates to a process and an apparatus for manufacturing a preform to be used for molding of fiber reinforced plastics (FRP). More specifically, the invention relates to a process for manufacturing a preform, in a cross-section thereof, having a web portion and at least one pair of flange portions extending in opposite side each other through a branch portion from the web portion, and an apparatus therefor. Typical preforms that have such a cross-sectional configuration include those with a T-shaped or I-shaped cross-section. 
     BACKGROUND OF THE INVENTION 
     Fiber reinforced plastics (FRP) comprising reinforcing fibers such as carbon fibers, glass fibers or aramid fibers are used as material for structural members of automobiles and aircraft, etc. because they are light in weight and high in durability. 
     An autoclave molding has been known as a method to mold fiber reinforced plastics (FRP). With this molding method, a layered product of prepreg sheets comprising reinforcing fibers and high-ductility epoxy resin, for instance, is pressed and heated in an autoclave for curing to produce fiber reinforced plastics (FRP). 
     It is generally difficult, however, for prepreg sheets to serve for molding products having a complicated three-dimensional shape. Under the existing circumstances, autoclave molding of conventional prepreg sheets has not been widely practiced because it needs high material costs and long molding process times, which will lead to high overall product manufacturing costs. 
     Compared to this, a resin transfer molding (RTM) and a vacuum RTM are attracting attention because these molding methods can work at lower costs and shorter molding process times than an autoclave molding of conventional prepreg sheets. 
     In the RTM process, a layered product of dry reinforcing fiber cloths having no impregnated matrix resin is placed in a mold and a low-viscosity liquid matrix resin is injected to allow the reinforcing fibers to be impregnated with the matrix resin to achieve molding of fiber reinforced plastics (FRP). 
     As the RTM process uses the dry reinforcing fiber cloth as described above, it is possible to shape the reinforcing fiber cloth along a complicated three-dimensional shape in a mold. However, wrinkle-free, uniform fiber reinforced plastic (FRP) products having a high volume percentage of fiber (Vpf) such has those produced by an autoclave molding of prepreg sheets cannot be produced easily by simply placing the layered product of reinforcing fiber cloths along a surface of the mold. The volume percentage of fiber is defined as the percentage by volume of fiber relative to the total volume of the material containing that fiber. 
     In a method to solve this problem, there is a method using a preform that is pre-formed in a shape of a final product in a dry state without a matrix resin impregnation. However, the time required to prepare such a preform and the accuracy of the resulting preform will have large influence on the production cost and quality of the final fiber reinforced plastic (FRP) product. 
     Thus, a preform production process that can be performed in a shorter time is proposed in Patent Literature 1. 
     The process disclosed in Patent Literature 1, however, cannot work satisfactorily to provide a wrinkle-free, uniform preform having a high volume percentage of fiber (Vpf) that can be used for molding of fiber reinforced plastics (FRP) having high mechanical characteristics such as those for aircraft&#39;s structural members. 
     CITATION LIST 
     Patent Literature 1: JP 2005-324513 A 
     SUMMARY OF INVENTION 
     The invention provides a preform manufacturing process that can continuously produce a wrinkle-free, uniform preform having a high volume percentage of fiber (Vpf) that can be used for molding of fiber reinforced plastics (FRP) having high mechanical characteristics such as those for aircraft&#39;s structural members, and also provide a manufacturing apparatus therefor. 
     The present inventors studied on why a wrinkle-free, uniform preform having a high volume percentage of fiber (Vpf) that can be used for molding of fiber reinforced plastics (FRP) having high mechanical characteristics could not be produced by simply using a combination of folding, lamination, adhesion, etc. of reinforcing fiber cloths, and turn their attention to the straightness of the reinforcing fiber in the course of the manufacturing process and the uniformity of reinforcing fiber density in the intermediate product. 
     Subsequently, they attempted to provide, in the manufacturing process, a partial shape forming step in which a fiber base material constituting a major portion of a preform to be manufactured was pre-formed for forming a preliminary shaped body. They tried to obtain an intended preform by uniting the resulting preliminary shaped body and a fiber base material constituting another portion of the preform in a uniting step providing after the partial shape forming step. 
     They found that wrinkles that would result from the difference in the circumference between the inside and outside of the fiber base material during the pressing in the thickness direction in producing a preform in the uniting step were completely eliminated or minimized to a very low level by properly distributing heating and/or pressing conditions of the fiber base material among in the partial shape forming step and the subsequent uniting step. 
     The process to manufacture such a preform and the manufacturing apparatus therefor according to aspects of the invention are described below: 
     (1) A process for manufacturing a preform comprising a first reinforcing fiber base material having, in its cross-section, a web portion and at least one pair of flange portions extending in opposite side each other through at least one branching portion from the web portion, and at least one second reinforcing fiber base material that is united with the first reinforcing fiber base material in a state including the at least one branching portion between them wherein: 
     (a) the first reinforcing fiber base material comprises a first raw base material and a second raw base material, 
     (b) the first raw base material comprises a first layered strip comprising layered multiple reinforcing fiber cloths and an is adhesive resin provided between the layered reinforcing fiber cloths, 
     (c) the second raw base material comprises a second layered strip comprising layered multiple reinforcing fiber cloths and an adhesive resin provided between the layered reinforcing fiber cloths, 
     (d) the second reinforcing fiber base material comprises at least one third raw base material, 
     (e) a first supply step for supplying the first layered strip, a second supply step for supplying the second layered strip, and at least one third supply step for supplying the at least one third raw base material are provided, 
     (f) a first partial shaping step is provided on the downstream side of the first supply step for shaping the first layered strip by heating and/or pressing and maintaining the shaped state, thereby producing a first preliminary shaped body, 
     (g) a second partial shaping step is provided on the downstream side of the second supply step for shaping the second layered strip by heating and/or pressing and maintaining the shaped state, thereby producing a second preliminary shaped body, 
     (h) a uniting step is provided on the downstream side of the first and second partial shaping steps and the at least one third supply step to unite the first and second preliminary shaped bodies produced in the first and second partial shaping steps in such a way that the branching portion is formed in the preform and the at least one third raw base material is added at the branching portion formed, followed by uniting them by heating and/or pressing them in the configuration and maintaining the united state, thereby providing the preform, 
     (i) a conveyance step is provided on the downstream side of the uniting step to intermittently convey the preform produced in the uniting step, and 
     (j) the production of the first and second preliminary shaped bodies in the first and second partial shaping steps and the production of the preform in the uniting step are carried out during the periods when the conveyance of the preform in the conveyance step is suspended. 
     (2) The process for manufacturing a preform, wherein said first and second preliminary shaped bodies meet the relationship 0.95≧α/β≧0.6 where α is their respective volume percentage of fiber and β is the volume percentage of fiber in said preform. 
     (3) The process for manufacturing a preform, wherein said volume percentage of fiber of α and said volume percentage of fiber of β meet the relationship 0.95≧α/β≧0.8. 
     (4) The process for manufacturing a preform, wherein a trimming step is provided on the downstream side of said uniting step and on the upstream side of said conveyance step to remove unnecessary parts from the preform produced in said uniting step. 
     (5) The process for manufacturing a preform, wherein at least one corner filler supply step is provided so that at least one corner filler comprising a reinforcing fiber bundle is supplied to at least one concave portion formed along the outer surface of said at least one branching portion produced in said uniting step in coordination with the intermittent preform conveyance motion in said conveyance step. 
     (6) The process for manufacturing a preform, wherein the reinforcing fiber bundle constituting said corner filler is a reinforcing fiber bundle containing an adhesive resin, and at least one corner filler partial shaping step that shapes said reinforcing fiber bundle containing the adhesive resin by heating and/or pressing and maintaining the shaped state to produce at least one preliminary shaped corner filler body is provided between said at least one corner filler supply step and said uniting step to allow the preliminary shaped corner filler body thus produced to be supplied to said uniting step. 
     (7) The process for manufacturing a preform, wherein said at least one third raw base material comprises at least one third layered strip comprising layered multiple reinforcing fiber cloths and an adhesive resin provided between the layered reinforcing fiber cloths, and at least one third partial shaping step that shapes said at least one third layered strip by heating and/or pressing and maintaining the shaped state to produce at least one third preliminary shaped body is provided between said at least one third supply step and said uniting step to allow said at least one third preliminary shaped body thus produced to be supplied to said uniting step. 
     (8) The process for manufacturing a preform, wherein the cross-section of said first preliminary shaped body and that of said second preliminary shaped body have L shapes that are bilaterally symmetric while one cross-section of said one third preliminary shaped body has a flat plate shape, and wherein in said uniting step, said L-shaped first preliminary shaped body and said L-shaped second preliminary shaped body are united at the position corresponding to said L-shaped web portion while said flat-plate-shaped third preliminary shaped body and said preliminary shaped corner filler body are united to form a T-shaped preform. 
     (9) The process for manufacturing a preform, wherein the cross-section of said first preliminary shaped body and that of said second preliminary shaped body have C shapes that are bilaterally symmetric while the cross-sections of said two third preliminary shaped bodies have flat plate shapes, and wherein in said uniting step, said C-shaped first preliminary shaped body and said C-shaped second preliminary shaped body are united at the position corresponding to said C-shaped web portion while said two flat-plate-shaped third preliminary shaped bodies are united with said two preliminary shaped corner filler bodies to form an I-shaped preform. 
     (10) An apparatus for manufacturing a preform comprising a first reinforcing fiber base material having, in its cross-section, a web portion and at least one pair of flange portions extending in opposite side each other through at least one branching portion from the web portion, and at least one second reinforcing fiber base material that is united with the first reinforcing fiber base material in a state including the at least one branching portion between them wherein: 
     (a) the first reinforcing fiber base material comprises a first raw base material and a second raw base material, 
     (b) the first raw base material comprises a first layered strip comprising layered multiple reinforcing fiber cloths and an adhesive resin provided between the layered reinforcing fiber cloths, 
     (c) the second raw base material comprises a second layered strip comprising layered multiple reinforcing fiber cloths and an adhesive resin provided between the layered reinforcing fiber cloths, 
     (d) the second reinforcing fiber base material comprises at least one third raw base material, 
     (e) a first supply unit to supply the first layered strip, a second supply unit to supply the second layered strip, and at least one third supply unit to supply the at least one third raw base material are provided, 
     (f) a first partial shaping unit is provided on the downstream side of the first supply unit to shape the first layered strip by heating and/or pressing and maintaining the shaped state, thereby producing a first preliminary shaped body, 
     (g) a second partial shaping unit is provided on the downstream side of the second supply unit to shape the second layered strip by heating and/or pressing and maintaining the shaped state, thereby producing a second preliminary shaped body, 
     (h) a uniting unit is provided on the downstream side of the first and second partial shaping units and the at least one third supply unit to unite the first and second preliminary shaped bodies produced in the first and second partial shaping units in such a way that the branching portion is formed in the preform and the at least one third raw base material is added at the branching portion formed, followed by uniting them by heating and/or pressing them in the configuration and maintaining the united state, thereby providing the preform, 
     (i) a conveyance unit is provided on the downstream side of the uniting unit to intermittently convey the preform produced in the uniting unit, and 
     (j) the production of the first and second preliminary shaped bodies in the first and second partial shaping units and the production of the preform in the uniting unit are carried out during the periods when the conveyance of the preform in the conveyance unit is suspended. 
     (11) The apparatus for manufacturing a preform, wherein a trimming unit is provided on the downstream side of said uniting unit and on the upstream side of said conveyance unit to remove unnecessary parts from the preform produced in said uniting unit. 
     (12) The apparatus for manufacturing a preform, wherein at least one corner filler supply unit is provided so that at least one corner filler comprising a reinforcing fiber bundle is supplied to at least one concave portion formed along the outer surface of said at least one branching portion produced in said uniting unit in coordination with the intermittent preform conveyance motion in said conveyance unit. 
     (13) The apparatus for manufacturing a preform, wherein the reinforcing fiber bundle constituting said corner filler is a reinforcing fiber bundle containing an adhesive resin, and at least one corner filler partial shaping unit that shapes said reinforcing fiber bundle containing the adhesive resin by heating and/or pressing and maintaining the shaped state to produce at least one preliminary shaped corner filler body is provided between said at least one corner filler supply unit and said uniting unit to allow the preliminary shaped corner filler body thus produced to be supplied to said uniting unit. 
     (14) The apparatus for manufacturing a preform, wherein said at least one third raw base material comprises at least one third layered strip comprising layered multiple reinforcing fiber cloths and an adhesive resin provided between the layered reinforcing fiber cloths, and at least one third partial shaping unit that shapes said at least one third layered strip by heating and/or pressing and maintaining the shaped state to produce at least one third preliminary shaped body is provided between said at least one third supply unit and said uniting unit to allow said at least one third preliminary shaped body thus produced to be supplied to said uniting unit. 
     (15) The apparatus for manufacturing a preform, wherein the cross-section of said first preliminary shaped body and that of said second preliminary shaped body have L shapes that are bilaterally symmetric while one cross-section of said one third preliminary shaped body has a flat plate shape, and wherein in said uniting unit, said L-shaped first preliminary shaped body and said L-shaped second preliminary shaped body are united at the position corresponding to said L-shaped web portion while said flat-plate-shaped third preliminary shaped body and said preliminary shaped corner filler body are united to form a T-shaped preform. 
     (16) The apparatus for manufacturing a preform, wherein the cross-section of said first preliminary shaped body and that of said second preliminary shaped body have C shapes that are bilaterally symmetric while the cross-sections of the two third preliminary shaped bodies have a flat plate shape, and wherein in said uniting unit, said C-shaped first preliminary shaped body and said C-shaped second preliminary shaped body are united at the position corresponding to said C-shaped web portion while said two flat-plate-shaped third preliminary shaped bodies are united with two preliminary shaped corner filler bodies to form an I-shaped preform. 
     (17) The apparatus for manufacturing a preform, comprising said first partial shaping unit, said second partial shaping unit and said third partial shaping unit that are combined into one partial shaping die wherein: 
     (a) said partial shaping die comprises a central die fixed on a stand, an upper die provided above said central die with a gap in between, and a lower die provided below said central die with a gap in between, 
     (b) said upper die and said central die have first shaping faces to receive and then heat and/or press said first layered strip and second shaping faces to receive and then heat and/or press said second layered strip, 
     (c) said lower die and said central die have third shaping faces to receive and then heat and/or press said third layered strip, 
     (d) a first actuator to move said upper die relative to said central die is provided on said upper die while a second actuator to move said lower die relative to said central die is provided on said lower die, and 
     (e) a hole is provided in the central region of said central die to allow said preliminary shaped corner filler body to pass through. 
     (18) The apparatus for manufacturing a preform, comprising said at least one corner filler partial shaping unit wherein: 
     (a) the unit comprises a corner filler shaping die comprising a flat die fixed on a stand, and a right and a left upper dies fixed respectively on the top face of said flat die, 
     (b) said right upper die has a left-side curved face in its left lower edge while said left upper die has a right-side curved face in its right lower edge, said right upper die and said left upper die being in contact with each other in such a way that said left-side curved face and said right-side curved face are faced with each other, 
     (c) the portion surrounded by the flat die&#39;s top face, said left-side curved face and said right-side curved face constitutes a hole to allow a reinforcing fiber bundle to pass through, said reinforcing fiber bundle being used to produce the corner filler to be supplied from said at least one corner filler supply unit, and 
     (d) the cross-sectional size of said hole gradually decreases in the traveling direction of said reinforcing fiber bundle. 
     (19) The apparatus for manufacturing a preform, comprising said uniting unit wherein: 
     (a) said uniting unit comprises a uniting die comprising a left upper die fixed on a stand, a right upper die provided on the right side of said left upper die with a gap in between and a lower die provided below said left upper die and said right upper die with a gap in between, 
     (b) said left upper die and said right upper die respectively have a first shaping face that belongs to said left upper die, and a second shaping face that belongs to said right upper die, to receive and heat and/or press said first preliminary shaped body and said second preliminary shaped body, 
     (c) said left upper die and said lower die respectively have a third shaping face that belongs to said left upper die, and a fourth shaping face that belongs to said lower die to receive and heat and/or press said first preliminary shaped body and said third preliminary shaped body, 
     (d) said right upper die and said lower die respectively have a fifth shaping face that belongs to said right upper die, and a sixth shaping face that belongs to said lower die to receive and heat and/or press said second preliminary shaped body and said third preliminary shaped body, and 
     (e) a first actuator is provided on said right upper die to move said right upper die relative to said left upper die while a second actuator is provided on said lower die to move said lower die relative to said left upper die and said right upper die. 
     Advantageous Effects of Invention 
     A preform manufacturing process or manufacturing apparatus according to aspects of the invention serves to intermittently convey in the longitudinal direction a raw base material for a reinforcing fiber base material having a branching portion in its cross-section that will constitute an intended preform, and heat and/or press the raw base material during a conveyance suspension periods to form a preliminary shaped body, followed by uniting the resulting preliminary shaped body with the raw base material for another reinforcing fiber base material that will constitute the intended preform, thereby enabling continuous production of the preform that has a branching portion in its cross-section. 
     Thus, the invention makes it possible to produce a high quality preform by preventing a decrease in the straightness of the reinforcing fiber, a decrease in the uniformity of the density, and in particular, wrinkles in the bent portion in the raw base material that would result from differences in the circumference between the inner and outer surfaces of the raw base material, all of which could take place when the two or more raw base materials for the reinforcing fiber base materials used to produce the intended preform are simply united by one heating and/or pressing step. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a schematic perspective view of a typical preform manufacturing apparatus according to one embodiment of the invention. 
         FIG. 2  shows a perspective view of a typical T-shaped preform to be produced by the manufacturing apparatus illustrated in  FIG. 1 . 
         FIG. 3  shows a schematic front view of a typical corner filler shaping die to be used in the corner filler partial shaping unit of the manufacturing apparatus illustrated in  FIG. 1 . 
         FIG. 4  shows a schematic front view of a typical partial shaping die to be used in the first, second and third partial shaping units of the manufacturing apparatus illustrated in  FIG. 1 . 
         FIG. 5  shows a schematic front view of a typical uniting-shaping die to be used in the uniting unit of the manufacturing apparatus illustrated in  FIG. 1 . 
         FIG. 6  shows a schematic front view of a typical preform gripping die to be used in the trimming unit of the manufacturing apparatus illustrated in  FIG. 1 . 
         FIG. 7  shows cross-sectional exemplary diagrams for explaining changes occurring in a form of fiber base material during production of a preform in a conventional preform manufacturing apparatus. 
         FIG. 8  shows schematic diagrams of the cross-sections of seven kinds of preforms that can be produced by the preform manufacturing process according to aspects of the invention. 
         FIG. 9  shows a schematic perspective view of another type of the preform manufacturing apparatus according to one embodiment of the invention. 
         FIG. 10  shows a perspective view of a typical I-shaped (or H-shaped) preform that may be produced by the manufacturing apparatus illustrated in  FIG. 9 . 
         FIG. 11  shows a schematic front view of a C-type preliminary shaping unit to be used in the manufacturing apparatus illustrated in  FIG. 9 . 
     
    
    
     REFERENCE SIGNS LIST 
     
         
         
           
             B 1 : branching portion 
             C 1 : uniting unit 
             Ca 1 : conveyance unit 
             Cf 1 : corner filler 
             CfB 1 : raw base material for corner filler 
             CfP 4 : corner filler partial shaping unit 
             CfPf 4 : preliminary shaped corner filler body 
             F 1 , F 1   a , F 1   b : flange portion 
             FL 1 : first supply unit 
             FL 2 : second supply unit 
             FB 1 : first reinforcing fiber base material 
             FB 2 : second reinforcing fiber base material 
             FCfB 1 : corner filler supply unit 
             FOB 3 : third supply unit 
             L 1 : first layered strip 
             L 2 : second layered strip 
             L 3 : third layered strip 
             OB 1 : first raw base material 
             OB 2 : second raw base material 
             OB 3 : third raw base material 
             P 1 : first partial shaping unit 
             P 2 : second partial shaping unit 
             P 3 : third partial shaping unit 
             PF 1 , PF 1   a , PF 1   b , PF 2 : preform 
             Pf 1 : first preliminary shaped body 
             Pf 2 : second preliminary shaped body 
             Pf 3 : third preliminary shaped body 
             T 1 : trimming unit 
             W 1 : web portion 
               6   a ,  6   b : preliminary shaped body 
               7   d ,  7   e ,  7   f ,  7   g : preliminary shaped body 
               8   a : preform 
               9   a : preform 
               10   a : material supply unit 
               20 : corner filler shaping die 
               20   a : filler shaping unit 
               30 : partial shaping die 
               30   a : partial shaping unit 
               40 : uniting-shaping die 
               40   a : uniting unit 
               50 : preform gripping die 
               50   a : trimming unit 
               60   a : traction unit 
           
         
       
    
     DETAILED DESCRIPTION 
     Some embodiments of the preform manufacturing process and manufacturing apparatus of the invention are described below by referring to drawings. 
     A preform PF 1  to be finally manufactured from a manufacturing apparatus (process) illustrated in  FIG. 1  has a T-shaped cross-section. A detailed perspective view of the preform is shown in  FIG. 2 . 
     In  FIG. 2 , the preform PF 1  comprises a first reinforcing fiber base material FB 1  which has, in its cross-section, a web portion W 1  and flange portions F 1   a  and F 1   b  extending on either side from the web portion W 1  through a branching portion B 1 , and a second reinforcing fiber base material FB 2  which is united with the first reinforcing fiber base material FB 1  with the branching portion B 1  being contained between them. A concave portion formed along the outer surface of the branching portion B 1  is closed by the second reinforcing fiber base material FB 2  along the longitudinal direction of the preform PF 1  and a gap is formed in the longitudinal direction of the preform PF 1 . The gap is filled with a corner filler Cf 1 . 
     A flange portion F 1  of the preform PF 1  comprises the flange portions F 1   a  and F 1   b  and the second reinforcing fiber base material FB 2 . The web portion W 1  is in the vertical direction relative to the flange portion F 1  which is placed in the horizontal direction, that is, to the flange portions F 1   a  and F 1   b  and the second reinforcing fiber base material FB 2  which are placed in the horizontal direction. 
     In  FIG. 1 , the first reinforcing fiber base material FB 1  comprises a first raw base material OB 1  and a second raw base material OB 2 . The first raw base material OB 1  comprises a first layered strip L 1  comprising layered multiple reinforcing fiber cloths and an adhesive resin provided in the interlayers. The second raw base material OB 2  comprises a second layered strip L 2  comprising layered multiple reinforcing fiber cloths and an adhesive resin provided in the interlayers. The second reinforcing fiber base material FB 2  comprises a third raw base material OB 3 . 
     In  FIG. 1 , the preform manufacturing apparatus (process) according to one embodiment of the invention comprises a first supply unit (step) FL 1  that supplies the first layered strip L 1 , a second supply unit (step) FL 2  that supplies the second layered strip L 2  and a third supply unit (step) FOB 3  that supplies the third base material OB 3 . 
     A first partial shaping unit (step) P 1  is provided on the downstream side of the first supply unit (step) FL 1  to shape the first layered strip L 1  by heating and/or pressing and maintaining the shaped state, thereby producing a first preliminary shaped body Pf 1 . A second partial shaping unit (step) P 2  is provided on the downstream side of the second supply unit (step) FL 2  to shape the second layered strip L 2  by heating and/or pressing and maintaining the shaped state, thereby producing a second preliminary shaped body Pf 2 . 
     A uniting unit (step) C 1  is provided on the downstream side of the first and second partial shaping unit (step) P 1  and P 2  and the third supply unit (step) FOB 3  to combine the first and second preliminary shaped bodies Pf 1  and Pf 2 , which are produced in the first and second partial shaping units (steps) P 1  and P 2 , so that they form the branching portion B 1  in the preform PF 1 , and to combine them with the third raw base material OB 3  so that it comes in contact with the branching portion B 1  formed above, followed by heating and/or pressing them in this state to unite them and maintaining the united state to provide a preform PF 1   a.    
     A conveyance unit (step) Ca 1  is provided on the downstream side of the uniting unit (step) C 1  to perform intermittent conveyance of the preform PF 1  produced in the uniting unit (step) C 1 . 
     The first and second preliminary shaped bodies Pf 1  and Pf 2  are produced in the first and second partial shaping units (steps) P 1  and P 2  and the preform PF 1  is formed in the uniting step C 1  during the periods when the conveyance of the preform PF 1  in the conveyance unit (step) Ca 1  is suspended. 
     The T-shaped preform PF 1  illustrated in  FIG. 2  which is produced by the manufacturing apparatus (process) illustrated in  FIG. 1  actually comprises L-shaped base materials Lf 1  and Lf 2 , which have bilaterally symmetric cross-sections, a flat-plate-shaped second reinforcing fiber base material FB 2  and a corner filler Cf 1 . The bilaterally symmetric L-shaped base materials Lf 1  and Lf 2  are united with each other in their web portions, and united further with the flat-plate-shaped second reinforcing fiber base material FB 2  in the flange portion, and the branching portion B 1  of the preform PF 1  is filled with the corner filler Cf 1 . 
     In this embodiment, furthermore, the third raw base material OB 3  that forms the flat-plate-shaped second reinforcing fiber base material FB 2  comprises layered multiple reinforcing fiber cloths and an adhesive resin provided in the interlayers as in the same manner as in the first raw base material OB 1  and the second raw base material OB 2 . 
     In this embodiment, furthermore, a reinforcing fiber bundle that forms the corner filler Cf 1  comprises a reinforcing fiber bundle that contains adhesive resin. 
     For manufacturing the preform PF 1 , the manufacturing apparatus (process) of this embodiment illustrated in  FIG. 1  has a third partial shaping unit (step) P 3  between the third supply unit (step) FOB 3  and the uniting unit (step) C 1  to shape a third layered strip L 3  by heating and/or pressing and maintaining the shaped state, thereby providing a third preliminary shaped body Pf 3 . 
     The manufacturing apparatus (process) illustrated in  FIG. 1 , furthermore, has a corner filler partial shaping unit (step) CfP 4  between a corner filler supply unit (step) FCfB 1 , which supplies the reinforcing fiber bundle containing adhesive resin (a raw base material for corner filler) CfB 1 , and the uniting unit (step) C 1  to shape the reinforcing fiber bundle containing adhesive resin (the raw base material for corner filler) CfB 1  by heating and/or pressing and maintaining the shaped state to provide a preliminary shaped corner filler body CfPf 4 . 
     The manufacturing apparatus (process) illustrated in  FIG. 1 , furthermore, has a trimming unit (step) T 1  between the uniting unit (step) C 1  and the conveyance unit (step) Ca 1  to remove unnecessary parts from the preform PF 1   a  produced in the uniting unit (step) C 1 . 
     A conventional tape supply unit that serves for continuous or intermittent supply of tape may be used as the first supply unit FL 1 , which works to pull out the first raw base material OB 1  (the first layered strip L 1 ), which is wound in a roll and fixed on a frame, and supplies it to the first partial shaping unit P 1 . A similar tape supply unit may also be used as the second supply unit FL 2 , the third supply unit FOB 3  and the corner filler supply unit FCfB 1 . 
       FIG. 3  shows a typical corner filler partial shaping unit CfP 4  that produces the preliminary shaped corner filler body CfPf 4 . In  FIG. 3 , the corner filler partial shaping unit CfP 4  comprises a corner filler shaping die  20 . The corner filler shaping die  20  comprises a flat die  22  fixed on a stand, as well as a right upper die  21   a  and a left upper die  21   b  that are fixed on the top face of the flat die  22 . The right upper die  21   a  has a left-side curved face  21   ac  at the left lower edge while the left upper die  21   b  has a right-side curved face  21   bc  at the right lower edge. The right upper die  21   a  and the left upper die  21   b  are in contact with each other in such a way that the left-side curved face  21   ac  and the right-side curved face  21   bc  are faced with each other. 
     The portion surrounded by the top face of the flat die  22 , the left-side curved face  21   ac  and the right-side curved face  21   bc  constitutes a hole  23  to allow the raw base material for corner filler (reinforcing fiber bundle) CfB 1  to pass through. The raw base material for corner filler is used to produce the corner filler Cf 1  which is supplied from the corner filler supply unit FCfB 1 . The cross-sectional size of the hole  23  gradually decreases in the traveling direction of the reinforcing fiber bundle CfB 1 . The reinforcing fiber bundle CfB 1  supplied to the hole  23  is shaped within the hole  23  to have an intended cross-section suited for filling the branching portion B 1 , thereby providing a preliminary shaped corner filler body CfPf 4 . The corner filler shaping die  20  is heated as required to facilitate the production of the preliminary shaped corner filler body CfPf 4 . The heating may be achieved by means of a heated fluid or electric heat supplied into the die. 
     In this embodiment, the first partial shaping unit P 1 , the second partial shaping unit P 2  and the third partial shaping unit P 3  are united into one partial shaping die.  FIG. 4  shows a typical partial shaping die. 
     In  FIG. 4 , the partial shaping die  30  comprises a central die  31  fixed on a stand, an upper die  32  provided above the central die  31  with a gap in between, and a lower die  33  provided below the central die  31  with a gap in between. The upper die  32  and the central die  31  respectively has a first shaping face  32 L 1  to receive the first layered strip L 1  and heat and/or press it, and a second shaping face  32 L 2  to receive the second layered strip L 2  and heat and/or press it. The lower die  33  and the central die  31  respectively has a third shaping face  33 L 3  to receive the third layered strip L 3  and heat and/or press it. 
     A first actuator  34   a  is fixed on the upper die  32  to move the upper die  32  relative to the central die  31 , allowing the upper die  32  to be moved away from or close to the central die  31 . A second actuator  34   b  is fixed on the lower die  33  to move the lower die  33  relative to the central die  31 , allowing the lower die  33  to be moved away from or close to the central die  31 . This structure allows the heating and pressing to be maintained during the partial shaping step and allows the die to be opened during the preform and reinforcing fiber base material conveyance step. Furthermore, a hole  35  is provided in the central region of the central die  31  to allow the preliminary shaped corner filler body CfPf 4  to pass through. The circumferential size of the hole  35  is larger than that of the preliminary shaped corner filler body CfPf 4  to allow the latter to pass through. 
     A heating unit, which is not shown in the drawing, is provided in the central die  31 , upper die  32  and lower die  33 . In the dies, the first layered strip L 1 , second layered strip L 2  and third layered strip L 3  are heated and pressed to achieve is partial shaping of the layered strips and soften or melt the adhesive resin provided in the interlayers so that the shape is fixed as a result of the adhesion of the interlayers, thereby providing a preliminary shaped body. 
     The shape of the central die  31  is such that its top face has two L-shaped concave portions (first shaping face  32 L 1  and second shaping face  32 L 2 ) while the bottom face is a flat plane. The upper die  32  has two L-shaped convex portions (first shaping face  32 L 1  and second shaping face  32 L 2 ), which form a gap against the two L-shaped concave portions of the central die  31  to produce the L-shaped cross-sections of the components Lf 1  and Lf 2  that constitute parts of the T-shaped cross-section. The top face of the lower die  33  is a flat plane and forms a gap against the bottom face of the central die  31  to produce the cross-section of the flat plate portion that constitutes a part of the T-shaped cross-section. 
       FIG. 5  illustrates a typical uniting unit C 1 . In  FIG. 5 , the uniting unit C 1  comprises one uniting-shaping die  40  comprising united components. The uniting-shaping die  40  comprises a left upper die  41   b  fixed on a stand, a right upper die  41   a  provided on the right side of the left upper die  41   b  with a gap in between, and a lower die  42  provided below the left upper die  41   b  and the right upper die  41   a  with a gap in between. 
     The right upper die  41   a  and the left upper die  41   b  respectively have a first shaping face  41   a   1   f , which belongs to the right upper die  41   a , and a second shaping face  41   b   1   f , which belongs to the left upper die  41   b , to receive and heat and/or press the first preliminary shaped body Pf 1  and the second preliminary shaped body Pf 2 . 
     The right upper die  41   a  and the lower die  42  respectively have a third shaping face  41   a   2   f , which belongs to the right upper die  41   a , and a fourth shaping face  42   af , which belongs to the lower die  42  to receive and heat and/or press the first preliminary shaped body Pf 1  and the third preliminary shaped body Pf 3 . 
     The left upper die  41   b  and the lower die  42  respectively have a fifth shaping face  41   b   2   f , which belongs to the left upper die  41   b , and a sixth shaping face  42   bf , which belongs to the lower die  42  to receive and heat and/or press the second preliminary shaped body Pf 2  and the third preliminary shaped body Pf 3 . 
     A first actuator  43   a  is provided on the right upper die  41   a  to move the right upper die  41   a  relative to the left upper die  41   b  while a second actuator  43   b  is provided on the lower die  42  to move the lower die  42  relative to the right upper die  41   a  and the left upper die  41   b.    
     With this die structure, the actuators  43   a  and  43   b  enable the right upper die  41   a  and the lower die  42  to be moved away from or closer to the left upper die  41   b . This allows the heating and pressing to be maintained during the partial shaping step and allows the die to be opened during the preform and reinforcing fiber base material conveyance step. 
     A heating unit, which is not shown in the drawing, is provided in the right upper die  41   a , left upper die  41   b  and lower die  42 . In the dies, the first preliminary shaped body Pf 1 , second preliminary shaped body Pf 2  and third preliminary shaped body Pf 3  are heated and pressed to soften or melt the adhesive resin on the surface of each preliminary shaped body that has its partial shape so that the layers are adhered to each other to fix the shape of each preliminary shaped body, followed by uniting these preliminary shaped bodies to provide a preform PF 1   a  having a T-shaped cross-section. 
       FIG. 6  illustrates a typical trimming unit T 1 . In  FIG. 6 , the trimming unit T 1  comprises a preform gripping die  50 . The preform gripping die  50  in  FIG. 6  comprises two central dies  51   a  and  51   b  and a lower die  52 . The preform gripping die  50 , furthermore, has trimming mechanisms  53   a ,  53   b  and  53   c  to remove unnecessary parts from the preform PF 1   a , which is produced in the uniting unit C 1 , to provide the preform PF 1  which is the final product. 
     The central die  51   a  is fixed on a stationary base, which is not shown in the drawing, and the central die  51   b  and the lower die  52  are connected to an actuator  54   a  and an actuator  54   b , respectively, so that they are pressed against or moved away from the central die  51   b . This motion allows the T-shaped preform PF 1   a , which has just molded in the uniting unit C 1 , to be gripped. 
     The central die  51   a  has a trimming mechanism  53   a , while the lower die  52  has two trimming mechanisms  53   b  and  53   c , each trimming mechanisms comprising rotary cutter blades  55   a ,  55   b  or  55   c . Each of this trimming mechanism has an actuator, which is not shown in the drawing, to move it in the direction toward its corresponding die and in the longitudinal direction of the preform. Each die, against which the corresponding rotary cutter blade is pressed, has a cutting mat  56   a ,  56   b  or  56   c , which is made of resin, to ensure that the reinforcing fiber to be cut will be pressed firmly against the cutter blade. 
     Though not illustrated in detail in the drawing, the conveyance unit (traction unit) Ca 1  comprises two or more dies and actuators to move them, as in the case of the uniting unit C 1 , and they are so configured that the T-shaped preform PF 1   b , which is supplied from the trimming unit T 1 , is gripped and that the entire mechanism to grip the preform PF 1   b  can be moved to and fro in the longitudinal direction of the preform PF 1  by means of an actuator AC 1 . 
     Each die in the corner filler shaping die  20 , partial shaping die  30  and uniting-shaping die  40  contains a flow channel for heating medium, which is not shown in the drawing, and the die can be adjusted to a desired temperature by passing a heating medium adjusted to that desired temperature through the flow channel to achieve contact heating of the work piece in the die. 
     A process for manufacturing a T-shaped preform PF 1  shown in  FIG. 2  based on using the apparatus for manufacturing a preform of the invention shown in  FIG. 1  is described below. As illustrated in  FIG. 2 , the T-shaped preform PF 1  comprises bilaterally symmetric L-shaped base materials Lf 1  and Lf 2 , a flat-plate-shaped base material FB 2  and a corner filler Cf 1 . 
     First, a roll OB 1  (the first raw base material) of the first layered strip L 1 , which will form the L-shaped base material Lf 1  which is one of the two L-shaped base materials, is fitted on the first supply unit FL 1 . Then a roll OB 2  (the second raw base material) of the second layered strip L 2 , which will form the other L-shaped base material Lf 2 , is fitted on the second supply unit FL 2 . Subsequently, a roll OB 3  (the third raw base material) of the third layered strip L 3 , which will form the flat-plate-shaped base material FB 2 , is fitted on the third supply unit FOB 3 . Furthermore, a roll CfB 1  (the corner filler raw base material) of a reinforcing fiber bundle impregnated with an adhesive resin, which will form the corner filler Cf 1 , is fitted on the corner filler supply unit FCfB 1 . This completes the preparation of the raw base materials. 
     Then, the layered strips L 1 , L 2  and L 3  and the reinforcing fiber bundle CfB 1  are pulled out of these rolls and passed though the entire length of the preform manufacturing apparatus to set up an initial state. The equipment is started after an initial state is established. 
     In the conveyance unit Ca 1 , the layered strips L 1 , L 2  and L 3  and the reinforcing fiber bundle CfB 1  existing there are gripped to allow the following three operations to be performed alternately: conveyance operation to pull them toward the downstream side of the manufacturing apparatus (to the right in  FIG. 1 ), each raw base material processing operation performed in the partial shaping die  30  (see  FIG. 4 ) and the uniting-shaping die  40  (see  FIG. 5 ) during conveyance suspension periods, and preform processing operation performed in the preform gripping die  50  (see  FIG. 6 ) in the trimming unit. 
     By these operations, the preform PF 1  having a T-shaped cross-section is produced step by step in the downstream direction, and preform production in a stationary state starts when all material strips have reached the end of the equipment. 
     The flow of the material processing, from upstream to downstream steps, is described below. The reinforcing fiber bundle CfB 1  pulled out from the corner filler roll by the traction force of the conveyance unit Ca 1  provided at the downstream end travels through the hole  23  which has a cross-section corresponding to that of the corner filler to be shaped in the corner filler shaping die  20  (see  FIG. 3 ). The right upper die  21   a , left upper die  21   b  and flat die  22  are heated by the heating medium flowing in each die. 
     The hole  23  has a larger cross-section at the entrance side thereof and is processed in the inner portion thereof so as to produce a corner filler having a desired cross-sectional shape to fill the T-shaped branching portion. As the bulky reinforcing fiber bundle CfB 1  is pressed and heated while passing through the hole  23 , the thermoplastic resin contained is softened and deformed and the reinforcing fiber bundle CfB 1  is processed to have the same cross-sectional shape as that of the intended corner filler. After coming out of the corner filler shaping die (preliminary shaping unit)  20 , the reinforcing fiber bundle CfB 1  processed is allowed to cool at room temperature and fixed while keeping the processed shape to become the preliminary shaped corner filler body CfPf 4 . 
     In this way, the operation at an early stage to adjust the cross-section of the corner filler to that of the final intended shape serves to allow the filler to be fed to the proper position by preventing the filler material from being pressed out of the curved portion into a straight portion and also preventing the position of the filler from being displaced to cause its density to become ununiform as the filler is united with other preliminary shaped bodies in the subsequent uniting unit C 1 . 
     On the other hand, the layered strips L 1 , L 2  and L 3  are pulled out of the respective rolls and then introduced to the partial shaping die  30  (see  FIG. 4 ). Here, the central die  31 , upper die  32  and lower die  33  are heated by the heating medium flowing inside them. The upper die  32  and lower die  33  are moved by the actuator  34   a  and  34   b , respectively, while the dies are open, and then the layered strips L 1 , L 2  and L 3  in the dies are pressed as they are closed. 
     At the same time, heat is supplied from the dies to heat them and this state is maintained for a specific period of time. While maintained in such a pressed and heated state, the layered strips L 1 , L 2  and L 3  not only deform into the same shape as the respective dies but also increase in the volume percentage of fiber. In this way, each strip reaches a volume percentage of fiber that is equivalent to or nearly the same as that of the intended L-shaped and flat-plate-shaped portions that will constitute the portion of the preform having a T-shaped cross-section. 
     As the thermoplastic resin contained in the interlayers in each layered strip is softened and deformed, the layers of the reinforcing fiber cloths that constitute the layered strip are adhered to each other, and maintained in a pressed state. 
     The upper die  32  and lower die  33  are opened by means of the actuator  34   a  and  34   b  after maintaining the strip in the shaping die  30  for a specific period of time. The layered strip processed is sent downstream again by the conveyance unit Ca 1  and allowed to cool so that the thermoplastic resin inside the strip cures to keep the shape formed. From the layered strips L 1 , L 2  and L 3 , the L-shaped preliminary shaped bodies Pf 1  and Pf 2  and the flat-plate-shaped preliminary shaped body Pf 3 , which respectively constitute parts of the T-shaped cross-section, are produced. 
     In cases where adhesive resin (thermoplastic resin) has been applied over the uniting face of the layered strips, as in the interlayers, to allow the preliminary shaped bodies to be united easily in the subsequent uniting step, the preliminary shaped bodies can stick to the central die  31  by the adhesive function of the resin as the preliminary shaped bodies are taken out of the shaping die after completing the pressing and opening the die. To prevent this phenomenon, it is recommended to apply previously a release agent such as polytetrafluoroethylene (Teflon (registered trademark)) over at least the surface of the central die  31 . 
     Furthermore, if a nozzle that feeds air to the gap between the preliminary shaped bodies and the central die  31  is provided to facilitate their release by the action of a high-speed air flow supplied in between the preliminary shaped bodies and the central die  31 , such an air flow will serve effectively to prevent damage to the preliminary shaped bodies and accelerate the cooling, thereby allowing the pressed state to be maintained firmly. 
     Instead, a layered strip may be produced with a release sheet (release paper) that is commonly used in the field of molding of a resin, etc., provided between the layered strip and the shaping die, and the release sheet may be removed after the layered strip produced has been taken out of the shaping die. 
     The partial shaping die  30  shown in  FIG. 4  has a structure that serves to produce a total of three preliminary shaped bodies, namely, two L-shaped ones on the top face of the central die  31  and a flat-plate-shaped one on the bottom face of the central die  31 , by a single pressing motion in the vertical direction. This makes it possible to use a shaping die having a simple structure, reduce the equipment cost, and minimize the total surface area of the dies. This serves to increase the thermal efficiency of the heating medium for temperature control of the dies. 
     In addition, the hole  35  is provided at the center of the central die  31  in the partial shaping die  30  that is shown in  FIG. 4 . The preliminary shaped body CfPf 4  for the corner filler that is produced in the corner filler partial shaping unit CfP 4  passes through the hole  35  before reaching the uniting unit C 1 . The hole  35  through which the preliminary shaped body CfPf 4  for the corner filler provided in the partial shaping die  30  serves to supply the preliminary shaped corner filler body CfPf 4 , which has become rigid by the preliminary shaping operation, to the uniting unit C 1  without bending it forcibly. 
     This makes it possible to maintain the straightness of the preliminary shaped corner filler body CfPf 4  during the final operation to provide a T-shaped preform. In designing the equipment, furthermore, a path for the preliminary shaped corner filler body CfPf 4  provided in the shaping die serves to minimize the distance between the members for processing the two L-shaped components. This serves to minimize the degree of the bending force that is applied to the completed L-shaped preliminary shaped bodies Pf 1  and Pf 2  sent to the uniting unit C 1 . As a result, damage to the preliminary shaped bodies Pf 1  and Pf 2  during the manufacturing process can be reduced. 
     Then, as the resulting preliminary shaped bodies Pf 1 , Pf 2 , Pf 3  and CfPf 4  are conveyed downstream, they are gathered to form a T-shaped cross-section. In the present embodiment, the preliminary shaped bodies Pf 1  and Pf 2  that form the L-shaped portions are twisted in the opposite directions by 45° around the length axis and simultaneously bent to change the traveling direction. Then finally, the two L-shaped preliminary shaped bodies Pf 1  and Pf 2  are combined back to back with their perpendicular portions (web portions) in contact with each other, and the flat-plate-shaped preliminary shaped body Pf 3  is added to the horizontal portion, followed by feeding the corner filler preliminary shaped body CfPf 4  to the gap in the central branching portion and introducing it to the uniting unit C 1 . 
     At this point, the right upper die  41   a , left upper die  41   b  and lower die  42  of the uniting-shaping die  40  (see  FIG. 5 ) in the uniting unit are all open. The perpendicular and horizontal gaps between the die components that serve to produce the T-shaped cross-section should not be too large and should preferably be 1.2 to 1.5 times the total thickness of the combined preliminary shaped bodies. Such gaps can serve to allow the introduced preliminary shaped bodies to come to the proper position and fit their shapes, and also serve to minimize the damage that can be caused by abrasion with the dies when the preliminary shaped bodies are introduced. 
     When preliminary shaped bodies are combined with reinforcing fiber base materials in a uniting step in another embodiment, the gaps in the die should preferably be about 1.1 to 1.5 times the total thickness of the elements fed to the gaps. This serves to prevent the elements to be introduced to an improper position relative to the die. If the elements are bulky, atapered portion or a somewhat large curved portion should preferably be provided at the inlet of the die to prevent them from being dragged when they are introduced into the die. 
     After the preliminary shaped bodies have been introduced into the uniting-shaping die  40 , the actuator  43   a  works first to move the central die  41   a  to press the web portion of the T shape and then the actuator  43   b  works to move the lower die  42  to press the flange portion of the T shape. The die is heated by the heating medium flowing in it to allow the preliminary shaped bodies to be maintained in a simultaneously pressed and heated state for a specific time. 
     By carrying out this pressing and heating operation and maintaining that state, the thermoplastic resin applied over the surface of each preliminary shaped body is softened to perform its adhesion function to unite the preliminary shaped bodies and at the same time the volume percentage of fiber of the preliminary shaped bodies increases under compression, thereby achieving a volume percentage of fiber that is nearly equivalent to that of the product having a T-shaped cross-section. 
     After maintaining this state for a specific period of time, the central die  41   a  and the lower die  42  are moved by the actuators  43   a  and  43   b , respectively, to open the die. Then the preliminary shaped bodies processed are conveyed downstream again by the conveyance unit Ca 1  and allowed to cool after getting out of the die, and the thermoplastic resin contained inside is cured to maintain the shape, thereby producing the preform PF 1   a.    
     The preform PF 1   a  produced in the uniting unit C 1  is conveyed further downstream and introduced into the trimming unit T 1 . In the preform gripping die  50  in the trimming unit T 1 , the actuator  54   a  first works to move the central die  51   a  to grip the is T-shaped web portion and then the actuator  54   b  works to move the lower die  52  to grip the T-shaped flange portion. Subsequently, the trimming mechanisms  53   a ,  53   b  and  53   c  start to function to allow actuators that are not shown in the drawing to press the rotary cutter blades  55   a ,  55   b  and  55   c  against the edges of the preform PF 1   a , and at the same time they move in the longitudinal direction of the preform PF 1   a  to cut the edges of the preform PF 1   a.    
     Then the rotary cutter blade  55   a ,  55   b  and  55   c  move away from the preform PF 1   a  and return to their original positions, and the actuator  54   a  and  54   b  work to move the central die  51   a  and the lower die  52 , respectively, to open the dies. The preform PF 1   b  trimmed is conveyed downstream again by the conveyance unit Ca 1 . 
     Finally, the preform PF 1   b  trimmed is conveyed further downstream and gripped by the preform grip mechanism contained in the conveyance unit Ca 1 . The actuator AC 1  then actuates the preform grip mechanism in the conveyance unit Ca 1  to grip the preform PF 1   b , and the mechanism moves downstream with the preform held. Here the preform PF 1   b  is released and the actuator AC 1  works again to move the preform grip mechanism upstream, leaving the preform PF 1   b  on the downstream side to provide the completed preform PF 1 . By repeating this motion, the completed preform PF 1  is sent downstream. This sequential manufacturing process continues to produce the preform PF 1  having a T-shaped cross-section without interruption as long as the raw base materials are supplied. 
       FIG. 9  shows a perspective view of another embodiment of the apparatus for manufacturing a preform of the invention that is different from that shown in  FIG. 1 . Whereas the embodiment illustrated in  FIG. 1  represents an apparatus to produce a preform having a T-shaped cross-section, the embodiment shown in  FIG. 9  represents an apparatus to produce a preform having an I-shaped cross-section. 
     In  FIG. 9 , the apparatus to manufacture a preform having an I-shaped cross-section comprises a material supply unit  10   a , a filler shaping unit  20   a , a partial shaping unit  30   a , a uniting unit  40   a , a trimming unit  50   a  and a traction unit  60   a  that are placed from upstream to downstream in this order. 
       FIG. 10  shows a perspective view of a typical preform having an I-shaped cross-section. The preform PF 2  given in  FIG. 10  comprises two C-shaped portion  70   a  and  70   b , each of which is produced by processing layered strip of reinforcing fiber cloths, two flat-plate-shaped portions  2   a  and  2   b , and corner fillers  3   a  and  3   b  to fill the gaps formed on the circumferential side of the bent regions. As in the case of the T-shaped one shown in  FIG. 2 , the perpendicular part and the horizontal part of the preform PF 2  shown in  FIG. 10  are referred to as web portion and flange portion, respectively. 
     The material supply unit  10   a  holds four layered strip rolls  11   d ,  11   e ,  11   f  and  11   g  that act as supply sources of the layered strips that form the two C-shaped portions  70   a  and  70   b  and the two-flat-plate portions  2   a  and  2   b , and filler material rolls  12   a  and  12   b  that act as supply sources of reinforcing fiber bundles that form the two corner filler  3   a  and  3   b.    
     A preliminary shaping die in the filler shaping unit  20   a  has two holes, each having a shape that corresponds to the cross-section of the corner filler to be used to fill each of the two branching portions in the final preform having an I-shaped cross-section. These two holes should preferably be located at proper positions in such a way that their axes coincide with those of the corner fillers in the uniting unit  40   a  placed downstream. 
     The partial shaping unit  30   a  comprises four preliminary shaping units including two C-shaped preliminary shaping units  71   a  and  71   b , each consisting of paired dies that form a gap having a C-shaped cross-section, and two flat-plate preliminary shaping units  72   a  and  72   b , each consisting of paired dies that form a gap having a straight cross-section. 
     The C-shaped preliminary shaping units  71   a  and  71   b  have the same shape.  FIG. 11  shows the cross-section of the C-shaped preliminary shaping unit  71   a , one of the pair. In  FIG. 11 , an inner die  711  placed inside the C-shaped gap is surrounded by a central die  712  and two side dies  713   a ,  713   b , with a C-shaped thin plate  714  held in between. The inner die  711  is fixed on a stationary base which is not shown in the drawing. The central die  712  and the side dies  713   a  and  713   b  are connected to actuators  715 ,  716   a  and  716   b , respectively. This allows the central die  712  and the side dies  713   a  and  713   b  to be moved away from and closer to the inner die  711 . In this way, the force to press the layered strips in the die unit is applied and removed. 
     The shaping dies contained in the uniting unit  40   a  are so configured that the gap formed between the paired dies has an I-shaped cross-section. 
     Each die in the filler shaping unit  20   a , partial shaping unit  30   a  and uniting unit  40   a  contains a structure therein for circulation of a heating medium to perform temperature control as in the case of the embodiment given in  FIG. 1 . This allows the dies to be adjusted to a required temperature for shaping. The dies in the partial shaping unit  30   a  and the uniting unit  40   a  are moved away from and closer to each other by means of actuators that are not shown in the drawing, allowing the material introduced to be heated and/or pressed. 
     As in the embodiment shown in  FIG. 1 , the trimming unit  50   a  has a trimming mechanism to adjust the shape of the edge of the preform produced. 
     The traction unit  60   a  has a preform grip mechanism to hold the I-shaped preform. Furthermore, the traction unit  60   a  has an actuator  61   a  to move the entire preform grip mechanism to and fro in the longitudinal direction of the preform. 
     In cases where the preform manufacturing apparatus shown in  FIG. 9  is used to produce the I-shaped preform shown in  FIG. 10 , the four layered strip rolls  11   d ,  11   e ,  11   f  and  11   g  and the two corner filler material rolls  12   a  and  12   b  are first mounted on the material supply unit  10   a . The materials used are the same as those in the embodiment shown in  FIG. 1 . 
     The flow of the material processing is described below from upstream to downstream. First, the reinforcing fiber bundles  5   a  and  5   b  pulled out of the filler material rolls  12   a  and  12   b  pass through the holes in the filler shaping unit  20   a , which have the same cross-sectional shape as the corner fillers to be produced, and simultaneously undergo heating and pressing to provide preliminary shaped bodies  6   a  and  6   b  that have the same cross-sectional shape as the intended corner filler. 
     The layered strips  4   d ,  4   e ,  4   f  and  4   g  pulled out of the layered strip rolls  11   d ,  11   e ,  11   f  and  11   g  are introduced into the partial shaping unit  30   a . Here, the layered strips  4   d  and  4   e  are heated and pressed in the flat plate preliminary shaping units  72   a  and  72   b , and that state is maintained to provide flat-plate-shaped preliminary shaped bodies  7   d  and  7   e . The layered strips  4   f  and  4   g  are heated and pressed in the C-shaped shaping units  71   a  and  71   b , and that state is maintained to provide C-shaped preliminary shaped bodies  7   f  and  7   g.    
     As shown in  FIG. 11 , in the C-shaped shaping unit, the central die  712  and side dies  713   a  and  713   b  that are moved by means of the actuators  715 ,  716   a  and  716   b  to press a layered strip  4   f  against the inner die  711  with a thin plate  714  held in between. In this step, the order of moving the central die  712  and the side dies  713   a  and  713   b  is such that the central die  712  is moved first followed by the side dies  713   a  and  713   b . This can prevent wrinkles that can be result from the difference between the inside and outside circumferences that takes place when the layered strip  4   f  is bent. 
     The existence of the thin plate  714  serves to prevent the layered strip  4   f  from being pressed out into the gap between the central die  712  and the side dies  713   a  and  713   b . There are no specific limitations on the material type and thickness of the thin plate  714  as long as it is of flexible material that can be properly set in the die and the layered strip  4   f  can be pressed uniformly. Considering the durability and release properties, the thin plate  714  should preferably be a steel plate having a thickness of about 0.07 to 0.15 mm that is coated with fluorine-based resin. 
     The preliminary shaped bodies  6   a ,  6   b ,  7   d ,  7   e ,  7   f  and  7   g  are conveyed to the subsequent uniting unit  40   a  where they are gathered to form a preform having an I-shaped cross-section. During this step in this embodiment, the preliminary shaped bodies  7   f  and  7   g , in particular, that form the C-shaped portion is pulled out of the C-shaped shaping unit with its open part facing upward, but has to be turned sideways before it reaches the uniting unit  40   a  so that the open part comes to the side position of the I-shaped preform. Thus, the preliminary shaped bodies  7   f  and  7   g  are twisted by 90° in the opposite directions around the length direction, and at the same time they are moved closer to each other and bent to change the traveling direction. 
     Meanwhile, the corner filler preliminary shaped bodies  6   a  and  6   b  are sent to the uniting unit  40   a  without being damaged by the bending in this step if the axis of the hole in the filler shaping unit  20   a  coincides with that of the corner filler in the uniting unit  40   a  as described previously. 
     And finally, the two C-shaped preliminary shaped bodies  7   f  and  7   g  are combined, back to back, in their central regions, and the flat-plate-shaped preliminary shaped bodies  7   d  and  7   e  are combined to the top and bottom horizontal regions, followed by introducing them to the uniting unit  40   a  with the gaps at the corners being filled with the preliminary shaped bodies  6   a  and  6   b , which have already been processed to have the cross-sectional shape of the intended corner filler. 
     Then, in the uniting unit  40   a , the I-shaped web portion is clamped first, followed by the I-shaped flange portion, and they are maintained in a pressed and/or heated state to provide a preform  8   a  that has the same I-shaped cross-sectional shape as the final product except for the length of the edges. 
     Subsequently, the edges of the preform  8   a  are trimmed in the trimming unit  50   a  to remove unnecessary parts, as in the case of the embodiment shown in  FIG. 1 , to provide an edge-trimmed preform  9   a  that has an intended cross-sectional shape. The edge-trimmed preform  9   a  is sent downstream through the traction unit  60   a  to enable continuous production of a preform PF 2  that has an I-shaped cross-sectional shape. 
     The preforms PF 1  and PF 2  produced in the above embodiment are then used as reinforcing fiber material to reinforce resin in a fiber reinforced plastics manufacturing process. Usually, a preform is cut to a required length and matrix resin is injected into the preform, followed by curing the injected resin to provide fiber reinforced plastics (FRP). 
     Two embodiments are described above by referring to  FIG. 1  and  FIG. 9 , but the invention is not limited by these embodiments. The existence of the partial shaping step and the uniting step in a continuous process is a feature of the method for continuous production of a preform that is high in the straightness of reinforcing fiber, uniform in the density of the reinforcing fiber in the preform and free of wrinkles. 
     The reinforcing fiber layered strip is heated and pressed in the partial shaping step; it is maintained in that state so that resin interlayers and other resin components contained in the reinforcing fiber cloth, along with the reinforcing fiber itself in some cases, are softened and allowed to flow to reduce the volume, thereby producing a preliminary shaped body has a properly finished partial shape that is equivalent to the corresponding part of the final cross-section; and the preliminary shaped body is united with other preliminary shaped bodies or other reinforcing fiber base materials in the uniting step to provide a complete preform. 
     This point is described more in detail below. For instance, if, in the T-shaped preform production process in the above embodiment, a layered strip comprising three layers of reinforcing fiber cloths is pressed in the uniting unit (uniting-shaping die  40 ) shown in  FIG. 5  without processing it into a preliminary shaped body, wrinkles will result from the difference between the lengths in the inside and the outside of the layered strip that takes place along the line where the layered strip is bent to form the web portion and the flange portion that extend in different directions, even if the corner filler has been processed in a preliminary shaped body. 
     Wrinkles that can take place under such conditions are illustrated in the schematic diagram in  FIG. 7 . In  FIG. 7 , three bulky layered strips  81   a ,  81   b  and  81   c  before a pressing step are arranged between dies as shown in the state S 1  where reinforcing fiber cloth layers are maintained straight. Then, a web portion  81 W is pressed as seen in the state S 2 . As a flange portion  81 F is pressed subsequently, the compression of the layered strip will result in an excess length in the circumferential element in the region where the strip is bent as shown in the state S 3 . Thus, the wrinkles Wr are produced in the state S 3 . 
     The partial shaping step of the invention helps to prevent these wrinkles from taking place. In particular, wrinkles can easily result from the difference between the inside and outside circumferences that takes place in the region where the layered strip is bent to from a branching portion in the cross-section. To prevent the formation of these wrinkles as effectively as possible, a base material that will form a branching portion in the cross-section of a preform should be properly processed to have such a cross-sectional shape having a branching portion before it is united with other base materials to produce a preform. 
     The branching portion is defined as the region where the web portion and the flange portion cross each other to form a T-shaped, Y-shaped or cross-shaped cross-section. Thus, the present invention is particularly effective in producing a preform having a cross-section having a branching portion.  FIG. 8  shows seven preforms having a branching portion. 
     A preform PF 3  shown in  FIG. 8 , which is the same as the preform PF 1  shown in  FIG. 2 , has a branching portion B 3 . A preform PF 4 , which is the same as the preform PF 2  shown in  FIG. 10 , has branching portions B 4  and B 5 . A preform PF 5 , in which the top end of the web portion is bent to the right, has a branching portion B 6 . A preform PF 6  has a cross-shaped cross-section having a branching portion B 7 . A preform PF 7  is a combination of a T-shaped and I-shaped preforms having branching portions B 8  and B 9 . A preform PF 8  is a combination of T-shaped preforms united in parallel each other having branching portions B 10  and B 11 . A preform PF 9 , in which the upper part of the web portion is bent to the right and the end part is bent upward, has a branching portion B 12 . 
     After being heated and pressed in the partial shaping step, the layered strip is processed to maintain the resulting shape so that it can be compressed to form a preliminary shaped body having an increased volume percentage of fiber (Vpf). This compression should preferably be performed to the extent that a cross-section of the preliminary shaped body becomes close to the final cross-section, or that its volume percentage of fiber (Vpf) is close to or same to that of the preform coming out of the uniting step. Such a degree of compression of the layered strip serves to prevent the wrinkles describe above from taking place in the uniting step. 
     In terms of the processing capacity of the apparatus for continuously preform production, however, the factor that determines the processing speed of the apparatus is the retention time in each step required to decrease the volume of the layered strip by heating and pressing. A long retention time in the partial shaping step is required to allow the partial shaping step to achieve a volume percentage of fiber (Vpf) nearly equal to that at the ending time of the uniting step, whereas the uniting step can be finishes in a very short retention time required to adhere each preliminary shaped body. Therefore, the overall processing capacity depends on the long retention time in the partial shaping step, but this is not efficient. And this causes a serious problem when the intended final volume percentage of fiber (Vpf) is relatively high, for example, 40% or above, or when the layered strip contains a large amount of interlayer resin. 
     An effective way to solve this problem is to control the volume percentage of fiber (Vpf) in the partial shaping step at a level that is relatively low but will not have adverse influence on the subsequent uniting step, followed by achieving the intended final volume percentage of fiber (Vpf) in the uniting step. Such a level of volume percentage of fiber (Vpf) that is relatively low but will not have adverse influence should preferably meet the following equation.
 
0.95≧α/β≧0.6
 
or more preferably
 
0.95≧α/β≧0.8
 
     Where α and β represent Vpf of the preliminary shaped body and that of the preform, respectively. 
     Thus, if the Vpf of the preliminary shaped body is controlled at about 60% to 95%, more preferably 80% to 95%, of that of the preform, the work of compressing the layered strips can be shared between the two steps for partial shaping and uniting to prevent an excessively long time from being consumed by either step, thereby minimizing the overall processing time of the manufacturing apparatus. And this serves very effectively to prevent wrinkles and ununiform density distributions in the reinforcing fiber in the uniting step. 
     To measure the volume percentage of fiber (Vpf), firstly, it is necessary to measure a thickness of a measuring sample, that is, a raw base material of a reinforcing fiber base material, a layered strip or a preliminary shaped body. The thickness of the measuring sample is measured under a pressure of 101.3 kPa applied in the vertical direction to the surface of the measuring sample. The method used to apply the pressure may be wrapping the measuring sample with a sheet such as film, followed by evacuation to apply an air pressure, or placing the measuring sample between a flat plate and a pressure plate (for instance, a disk of 25 mm diameter), followed by applying to the pressure plate a suitable force that depends on the size of the pressure plate. The data relating to thickness and volume percentage of fiber (Vpf) given in the present specification are based on measurements by the evacuation method. 
     In carrying out aspects of the invention, it is not necessary to perform partial shaping for all portions as described in the above embodiments. In the case of a preform having a T-shaped cross-section, for instance, a partial base material having no bent portion, such as a flat-plate-shaped portion to be combined with a flange portion, may not undergo a partial shaping step, but may be used in the form of the original layered strip and united with a partial shaped L-shaped portion. Thus, at least one portion that will constitute an important part of the final preform in terms of straightness of the reinforcing fiber and uniformity of the density may be processed into a preliminary shaped body and then united not only with other preliminary shaped bodies but also with other reinforcing fiber base materials having no formed partial shape therein. 
     The second reinforcing fiber base material to be united with the first reinforcing fiber base material to form a preform may not necessarily be a layered strip comprising layered multiple reinforcing fiber cloths and an adhesive resin provided between the layered reinforcing fiber cloths such as used in the above embodiments, but may be a layered strip having no adhesive resin between the layered reinforcing fiber cloths, a simple sheet of reinforcing fiber cloth, or a rod or a tube of a reinforcing fiber cloth, as the case may be. 
     A thermoplastic resin is used in the above embodiments as the adhesive resin provided in the interlayers of the layered strip or applied over its surface as the case may be, such thermoplastic resins including, for instance, a polyolefin resin, styrene-based resin, polyamide resin and polyurethane resin. The adhesive resin may also be a thermosetting resin such as, for instance, an epoxy resin, phenol resin or unsaturated polyester resin. The adhesive resin, however, should work as an adhesive when heated. Considering their handling at ordinary temperature, the adhesive resin should preferably have a glass transition temperature (Tg) in the range of about 30 to 100° C. Such resins may be used as the adhesive resin contained in the reinforcing fiber bundle for the corner filler. 
     The adhesive resin may be in the form of fiber, particle or emulsion. The adhesive resin may not necessarily be existed in the interlayers in the layered reinforcing fiber cloths, but may be dispersed randomly inside the reinforcing fiber cloth. When an adhesive resin in a form of fiber is used, the adhesive resin fiber may be lined up in the reinforcing fiber bundle, used as auxiliary yarns inserted as warps and/or wefts into a woven fabric, used as stitching yarns inserted through multiple layers of reinforcing fiber cloths. There are no specific limitations on the form of the adhesive resin if the interlayers can be adhered by heating and pressing. 
     There are no specific limitations on the type of the reinforcing fiber that constitutes the reinforcing fiber cloth and corner filler. Useful reinforcing fibers include, for instance, carbon fiber, glass fiber, organic fiber (such as aramid fiber, polyparaphenylene benzobisoxazole fiber, phenol fiber, polyethylene fiber, polyvinyl alcohol fiber), metal fiber, ceramic fiber, and their combinations. In particular, carbon fiber is high in specific strength, specific modulus and water absorption resistance, and therefore preferable as material for structural members of aircraft and automobiles that require high mechanical characteristics. 
     There are no specific limitations on the form of the reinforcing fiber cloth if it comprises reinforcing fibers arranged at least in one direction. Useful forms of reinforcing fiber cloth include woven fabric, knitted fabric, braided fabric, nonwoven fabric, unidirectional fiber sheet, which comprises reinforcing fibers arranged in one direction and morphologically stabilized with a binder, fusion-bonding type nonwoven fabric or stitch thread, and multi-axial sheet, which comprises unidirectional fiber sheets laminated with their directions of arranged fibers shifted from one another. In particular, preforms used to produce structural members of transport equipment, such as aircraft in particular, are required to have high mechanical characteristics (compressive strength in particular). To meet this requirement, unidirectional cloth and combined unidirectional cloth sheets are particularly preferred because they can achieve a high reinforcing fiber straightness and high volume percentage of fiber (Vpf). 
     For the supply of a layered strip, the layered strip should preferably be in the form a roll, if it is possible as in the above embodiments, because rolls are small in size and suitable for storage of long strips. If the layered strip is thick because of comprising many reinforcing fiber cloth layers, the layered strip is deformed as it is rolled up to cause a difference in the circumferential length of the layers, resulting in slippage between them. If the interlayers in the layered strip are adhered at some points, they can be removed, making it impossible to maintain the layered strip in the intended state. Such a layered strip should preferably be stored on a flat container such as tray without curling it. If each reinforcing fiber cloth layer to constitute the layered strip is in the form of a roll, several single layer rolls, whose number is the same as that of the layers in the final layered product, may be used to allow the reinforcing fiber cloth strips to be combined to provide a layered strip before being sent to the partial shaping step and uniting step. 
     As the processing means for heating and/or pressing a layered strip or preliminary shaped body, heated dies are pressed against each other in the above embodiments. This pressing method is preferred because a required temperature and pressure can be set up accurately and a required durability and operating stability are also achieved properly. 
     The material of the shaping dies to be used may be rigid one such as metal and resin, or a soft one such as rubber and elastomer. The dies, however, should preferably be made of a metal that is high in heat conduction, rate of heat transfer to the reinforcing fiber and, hopefully, durability, because the material in a die is heated by contact heating with the die. 
     Useful die heating means other than described above include the use of radiation heat, atmosphere heat and blast of heated gas. Useful die pressing means other than described above include wrapping the die with film-like material or putting it in a bag followed by applying an internal pressure. An appropriate heating means and pressing means are selected to meet the characteristics of the material and properties of the perform to be produced. 
     The heating temperature for processing a layered strip or preliminary shaped body should preferably be higher than the glass transition temperature (Tg) of the adhesive resin existing in the interlayers to allow then work effectively as adhesive. If the temperature is too high, however, an excessive amount of adhesive resin can form film-like resin layers between the reinforcing fiber cloth layers and prevent smooth flow of the matrix resin injected in a subsequent step, although the required processing time can be shorter. For an adhesive resin having a glass transition temperature (Tg) in the range of 30 to 100° C., the heating temperature for processing should preferably be in the range of about 40 to 130° C. 
     If the pressure applied in the pressing step is too high, the reinforcing fiber will deform in the thickness direction before the adhesive resin in the interlayer starts to flow, and the reinforcing fiber layers that are faced with each other with the interlayers in between will come in contact with each other to fill the space existing in the interlayers to prevent the flow of the interlayer resin during the subsequent step for matrix resin injection. The pressure should preferably be above the atmospheric pressure and in the range of 0.1 to 1.0 MPa. 
     The conveyance unit (traction unit) may be separate from others, but may be combined with the trimming unit. The conveyance unit (traction unit) performs the two functions of gripping the preform and carrying it in the longitudinal direction, but the trimming unit also has the gripping function, and therefore, if this gripping function is maintained at a satisfactorily high level, the trimming unit will be able to serve simultaneously to grip the material for conveyance (traction) while trimming it, making it possible, by adding a carrying function to this unit, to eliminate the conveyance unit (traction unit). 
     The preform manufacturing process or manufacturing apparatus of the present invention serves to intermittently convey in the longitudinal direction a raw base material for the reinforcing fiber base material having a branching portion in its cross-section that will constitute the intended preform, and heat and/or press the raw base material during the conveyance suspension periods to form a preliminary shaped body, followed by uniting the resulting preliminary shaped body with a raw base material of the other reinforcing fiber base materials that will constitute the intended preform, thereby enabling continuous production of a preform that has a branching portion in its cross-section. This prevents the formation of wrinkles, which are generally formed in the reinforcing fiber in a preform that is manufactured continuously by the conventional method, and serves for continuous manufacturing of a perform that can be used to produce structural members of, for instance, automobiles and aircraft.