Patent Publication Number: US-2020290297-A1

Title: Composite shaping apparatus and composite shaping method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2018-156865 filed on Aug. 24, 2018, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The disclosure relates to a composite shaping apparatus and a composite shaping method. 
     Composites, such as glass fiber reinforced plastics (GFRPs) and carbon fiber reinforced plastics (CFRPs), are formed by stacking sheet-shaped prepregs and thermally curing the stack of the prepregs. Some aircraft component parts, such as stringers, spars, and ribs, have T or I-shaped cross sections. To form such component parts, a stack of prepregs stacked in a planar shape, a stack of prepregs stacked so as to have an L or C-shaped cross section, and a stack of prepregs stacked so as to have a cross section whose shape is axially symmetrical to the L or C shape are combined before curing. 
     The corner of a stack of prepregs bent at right angle has a rounded shape. Therefore, when two squarely bent prepreg stacks are disposed symmetrically to each other so as to face and touch each other on a planar prepreg stack, a space having a substantially triangular cross section is formed between the prepreg stacks. More concretely, the three prepreg stacks define a space therebetween whose cross-sectional shape is determined by a straight line and two symmetrical arcs that correspond to the two rounded corners. 
     Therefore, the space formed between the three prepreg stacks is filled with a filler (filling material). Usually, a filler is prepared also as a prepreg stack and is thermally cured together with the other prepreg stacks. A bar-shaped filler whose cross-sectional shape is formed by two symmetrical arcs and a straight line is called a noodle filler. A noodle filler is manufactured by forming a round bar-shaped material obtained by stacking a prepreg into a coil shape. 
     Incidentally, the forming performed on a prepreg stack prior to thermal curing is generally called shaping in order to distinguish it from the forming of a composite by thermal curing. Therefore, the forming performed on a stack of prepregs will hereinafter be referred to as shaping. 
     With regard to related-art shaping methods for a prepreg stack, it is a general practice to use a molding die for shaping (a shaping die). For instance, a method in which a prepreg stack is set in a shaping die and shaped under a vacuum pressure, a method in which a prepreg stack is shaped by an extruder whose mouthpiece (die) is a shaping die whose shape corresponds to that of the stack obtained after the extrusion-shaping, a method in which a prepreg stack is shaped by pressing rollers against the prepreg stack, etc. are known. 
     However, the shaping methods that use vacuum pressure have a problem of long shaping times. Concretely, a typical prepreg stack shaping method that uses vacuum pressure requires several hours to about one day for the shaping. Furthermore, in the case where a bar-shaped filler, such as a noodle filler, is shaped, it is necessary to prepare a shaping die that is capable of shaping the whole filler. In the case where an extruder is used to shape a prepreg stack, the resistance in shaping is so large that a hefty apparatus is needed in order to pull out the stack. 
     As a shaping apparatus for a noodle filler, apparatuses that press a bar-shaped material with two rollers set in parallel have been proposed (see, e.g., Japanese Unexamined Patent Application Publication 4-299110). Such an apparatus can shape a noodle filler by clamping a bar-shaped material between a cylindrical roller and a roller that has a recess that corresponds in shape to the noodle filler and driving the bar-shaped material out from the gap between the two rollers. 
     Apparatuses that press a bar-shaped material by three rollers have also been proposed (see, e.g., Japanese Unexamined Patent Application Publication Nos. 2016-175242 and 2017-148985). Such a filler shaping apparatus having three rollers can shape a filler with sufficiently high quality because the apparatus can more uniformly press the filler from three directions. 
     SUMMARY 
     An aspect of the disclosure provides a composite shaping apparatus including at least one first roller configured to load a prepreg with pressure, at least one second roller configured to load the prepreg with pressure, and at least one motor that rotates at least one of the at least one first roller or the at least one second roller. The at least one first roller and the at least one second roller are rotated while at least one of rotation speed, roller diameter, or presence/absence of rotating power is made different between the at least one first roller and the at least one second roller. 
     An aspect of the disclosure provides a composite shaping method. The method includes loading the prepreg with pressure with the above composite shaping apparatus so that the shaped prepreg is manufactured using the above composite shaping apparatus 
     An aspect of the disclosure provides a composite shaping method includes manufacturing a shaped prepreg by rotating at least one of at least one first roller or at least one second roller by a motor and loading the prepreg with pressure by the at least one first roller and the at least one second roller while feeding the prepreg by the at least one first roller and the at least one second roller, and reducing wrinkle that is possibly formable on the prepreg, by rotating the at least one first roller and the at least one second roller, with at least one of rotation speed, roller diameter, or presence/absence of rotating power being made different between the at least one first roller and the at least one second roller in. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments and, together with the specification, serve to explain the principles of the disclosure. 
         FIG. 1  is a configuration diagram of a composite shaping apparatus according to a first embodiment of the disclosure; 
         FIG. 2  is a perspective view illustrating an example of a structure of a filler; 
         FIG. 3  is a perspective view illustrating an example of a structure of a stack of prepregs that is to be a material of a filler; 
         FIG. 4  is a schematic diagram illustrating a structure of a cross section of a filler that has been shaped by a composite shaping apparatus pressurizing a stack of prepregs from three directions; 
         FIG. 5  is a diagram illustrating a method for determining inclination angles of a second axis and a third axis with respect to a first axis indicated in  FIG. 1 ; 
         FIG. 6  is a view of a second roller, a second motor, and a power transmission mechanism for transmitting motive power from the second motor to the second roller illustrated in  FIG. 1  which is viewed from a direction A indicated in  FIG. 1 ; 
         FIG. 7  is a diagram illustrating advantageous effects obtained by causing a rotation speed difference among the first, second, and third rollers illustrated in  FIG. 1 ; 
         FIG. 8  is a right side view of the first and second rollers illustrated in  FIG. 7 ; 
         FIG. 9  is a configuration diagram of a composite shaping apparatus according to a second embodiment of the disclosure; 
         FIG. 10  is a configuration diagram of a composite shaping apparatus according to a third embodiment of the disclosure; 
         FIG. 11  is a left side view of a first roller unit illustrated in  FIG. 10 ; 
         FIG. 12  is a left side view of a second roller unit illustrated in  FIG. 10 ; 
         FIG. 13  is a configuration diagram of a composite shaping apparatus according to a fourth embodiment of the disclosure; 
         FIG. 14  is a configuration diagram of a composite shaping apparatus of a fifth embodiment disclosure; 
         FIG. 15  is a configuration diagram of a composite shaping apparatus according to a sixth embodiment of the disclosure; and 
         FIG. 16  is a configuration diagram of a composite shaping apparatus according to a seventh embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, some embodiments of the disclosure are described in detail with reference to the accompanying drawings. Note that sizes, materials, specific values, and any other factors illustrated in respective embodiments are illustrative for easier understanding of the disclosure, and are not intended to limit the scope of the disclosure unless otherwise specifically stated. Further, elements in the following example embodiments which are not recited in a most-generic independent claim of the disclosure are optional and may be provided on an as-needed basis. Throughout the present specification and the drawings, elements having substantially the same function and configuration are denoted with the same reference numerals to avoid any redundant description. Further, elements that are not directly related to the disclosure are unillustrated in the drawings. The drawings are schematic and are not intended to be drawn to scale. The shaping of a filler by rollers allows the shaping apparatus to be considerably reduced in size, in comparison with the shaping of a filler by an extruder, but has a problem that the surface of the filler and a roller sometimes deviate from each other so that wrinkles are formed on the surface of the filler. 
     For the forming of a hollow composite, forming methods for a composite hollow body which prevents formation of wrinkles by disposing a plurality of rolls and wrapping prepreg sheets over and over while heating and pressurizing the prepreg sheets have been proposed (see, e.g., Japanese Unexamined Patent Application Publication 7-80951). 
     However, a technique for preventing formation of a wrinkle on a filler during the shaping of the filler prior to thermal curing has not been devised. 
     It is desirable to make it possible to shape a composite prior to the thermal curing of a filler or the like, without allowing a wrinkle to be formed. 
     First Embodiment 
     (Configuration and Functions) 
       FIG. 1  is a configuration diagram of a composite shaping apparatus according to a first embodiment of the disclosure. 
     A composite shaping apparatus  1  is an apparatus for shaping a stack of prepregs P by using a plurality of rollers  2 . A prepreg P is a sheet-shaped bundle of fibers impregnated with an uncured thermosetting resin. In other words, a prepreg P is a sheet of a thermosetting resin reinforced with a sheet-shaped bundle of fibers. A shaped stack of prepregs P can be formed into a composite by heating the stack in an oven or an autoclave apparatus. Therefore, a stack of prepregs P that has been shaped can be considered a composite that has yet to be thermally cured. 
       FIG. 1  illustrates an example of the composite shaping apparatus  1  in which a filler F is shaped by using three rollers  2 A,  2 B, and  2 C. The filler F is a component part for filling a space that is formed between other composite component parts. 
       FIG. 2  is a perspective view illustrating an example of a structure of a filler F. 
     A typical filler F has a bar-shaped structure whose cross-sectional shape is determined by two symmetrical arcs and a straight line as illustrated as an example in  FIG. 2 . Concretely, the filler F has a shape that is determined by a rectangular flat surface whose width is W and whose length is L, a first curved surface whose cross section is an arc, and a second curved surface symmetrical to the first curved surface. Therefore, the height H of the filler F is the distance between the rectangular flat surface and a line of intersection of the first curved surface and the second curved surface. 
     The filler F that has a structure as illustrated in  FIG. 2  is used mainly to fill a space that is formed when two prepreg stacks each bent at right angle so as to form a round corner are placed symmetrically, facing and touching each other, and placed on a flat or slightly curved platy stack of prepregs. 
       FIG. 3  is a perspective view illustrating an example of a structure of a stack of prepregs P that can be used as a material of a filler. 
     In the case where, using the composite shaping apparatus  1 , the filler F that has a structure as illustrated as an example in  FIG. 2  is subjected to shaping prior to thermal curing, the filler F can be manufactured by using as a material a bar-shaped stack of prepregs P as illustrated in  FIG. 3 . The bar-shaped stack of prepregs P can be manufactured, for instance, by rolling one sheet-shaped prepreg P into a coil shape. Therefore, ideally, the material of the filler F is a round bar-shaped stack of prepreg P whose cross-sectional shape is substantially circular as illustrated in  FIG. 3 ; however, in reality, it is often the case that the cross-sectional shape of the stack of prepreg P is not accurately circular, because uncured resin easily deforms. 
     When a filler F having a structure as illustrated as an example in  FIG. 2  is shaped by the composite shaping apparatus  1 , the shaping of the filler F by the composite shaping apparatus  1  is a forming process in which the filler F is processed to obtain a flat surface whose width is W and whose length is L, a first curved surface whose cross section is an arc, and a second curved surface symmetrical to the first curved surface. 
       FIG. 4  is a schematic diagram illustrating a structure of a cross section of the filler F shaped by the composite shaping apparatus  1  pressurizing the stack of prepregs P from three directions. 
     Three rollers  2 A,  2 B, and  2 C are disposed at such positions as to clamp the bar-shaped stack of prepreg P rolled in a coil shape and the three rollers  2 A,  2 B, and  2 C are caused to apply pressure to the bar-shaped stack of prepregs P so as to carry out the shaping of the filler F. As a result, the cross section of the filler F obtains a coil structure as illustrated in  FIG. 4 . Therefore, the stacking directions of the prepreg P are perpendicular to the length of the filler F. 
     In order to shape a filler F that has a structure as illustrated as an example in  FIG. 4 , the composite shaping apparatus  1  can be constructed of three rollers  2 A,  2 B, and  2 C that apply pressures at mutually different angles to a stack of prepreg P stacked in a bar shape and a rotation mechanism  3  that rotates the three rollers  2 A,  2 B, and  2 C. Each of the three rollers  2 A,  2 B, and  2 C is a roller for shaping one of the flat surface and the two curved surface of the filler F. Therefore, the three rollers  2 A,  2 B, and  2 C rotate about three axes AX 1 , AX 2 , and AX 3  that are not parallel to one another. Specifically, the first, second, and third rollers  2 A,  2 B, and  2 C are disposed so that a space that corresponds to the cross-sectional shape of the filler F determined by two axially symmetrical arcs and one straight line is formed between the first, second, and third rollers  2 A,  2 B, and  2 C. 
     More concretely, the first roller  2 A rotates about the first axis AX 1 . The second roller  2 B rotates about the second axis AX 2  that is inclined with respect to the first axis AX 1 . The third roller  2 C rotates about the third axis AX 3  that is inclined with respect to the first axis AX 1  and that is symmetrical to the second axis AX 2  with respect to a plane perpendicular to the first axis AX 1 . 
     The first roller  2 A is a roller for shaping the flat surface whose width is W and whose length is L. Therefore, the first roller  2 A may be a cylindrical or hollow cylindrical roller that rotates about the first axis AX 1  extending in a horizontal direction. The second roller  2 B is a roller for shaping one of the curved surfaces of the filler F that correspond to round corners. Therefore, the second roller  2 B may be a circular disc-shaped roller having a circumferential portion whose cross section has a radius substantially equal to the radius of the curved surfaces of the filler F that correspond to the round corners. The third roller  2 C is a roller for shaping the other one of the curved surfaces of the filler F that correspond to the round corners. Therefore, the third roller  2 C, similar to the second roller  2 B, may be a circular disc-shaped roller having a circumferential portion whose cross section has a radius substantially equal to the radius of the curved surfaces of the filler F that correspond to the round corners. 
     However, since the curved surfaces of the filler F that correspond to the round corners are symmetrical to each other with respect to a plane, the second axis AX 2  of the second roller  2 B and the third axis AX 3  of the third roller  2 C are symmetrical to each other with respect to a plane perpendicular to the first axis AX 1 . It is important that the inclination angles of the second axis AX 2  and the third axis AX 3  to the first axis AX 1  be set to angles that are suitable for the shaping of the filler F. The angles of the second axis AX 2  and the third axis AX 3  that are suitable for the shaping of the filler F can be set from various viewpoints. 
       FIG. 5  is a diagram illustrating a method for setting the inclination angles of the second axis AX 2  and the third axis AX 3  with respect to the first axis AX 1  illustrated in  FIG. 1 . 
     Shaping tests were conducted with varied angles of the second axis AX 2  and the third axis AX 3 . Test results confirmed that disposing the first, second, and third rollers  2 A,  2 B, and  2 C so that the inclination angles of the second axis AX 2  and the third axis AX 3  to the first axis AX 1  are greater than or equal to 45 degrees and less than or equal to 60 degrees, in other words, setting the angles θ 1  and θ 2  of the directions of pressing the second roller  2 B and the third roller  2 C with respect to the surface of the first roller  2 A to angles greater than or equal to 30 degrees and less than or equal to 45 degrees, is suitable from the viewpoint that compression force should be uniformly applied to the three surfaces of the material. 
     Particularly, it was confirmed that setting the inclination angle of the second axis AX 2  and the third axis AX 3  with respect to the first axis AX 1  to angles within a predetermined tolerance from ±53.13 degrees, that is, setting the angles θ 1  and θ 2  of the direction of pressing the second roller  2 B and the third roller  2 C with respect to the surface of the first roller  2 A to ±36.87 degrees, substantially equalizes the maximum distances by which the three surfaces of a round bar-shaped material are compressed as illustrated in  FIG. 5  and therefore is suitable. 
     It was also confirmed that, from the viewpoint of improving the flatness of the lower surface of the filler F, it is suitable that the first, second, and third rollers  2 A,  2 B, and  2 C be disposed so that the inclination angles of the second axis AX 2  and the third axis AX 3  with respect to the first axis AX 1  are greater than or equal to 10 degrees and less than or equal to 40 degrees. That is, in order to improve the flatness of the lower surface of the filler F, it is suitable that the angles θ 1  and θ 2  at which the second roller  2 B and the third roller  2 C are pressed be greater than or equal to 50 degrees and less than or equal to 90 degrees. 
     Therefore, the preferable range of the inclination angles of the second axis AX 2  and the third axis AX 3  to the first axis AX 1  change depending on which of the uniformity of internal layers of the filler F and the flatness of the lower surface of the filler F is considered more important. 
     The concrete shapes and sizes of the first, second, and third rollers  2 A,  2 B, and  2 C can be determined according to the size of the filler F. For instance, it suffices that radii of the second roller  2 B and the third roller  2 C measured at their end portions are equal to the radii measured at the corresponding round surfaced portions of the filler F. The length of the first roller  2 A is set to a length that at least covers the lower surface of the filler F. 
     The diameters of the first, second, and third rollers  2 A,  2 B, and  2 C can be set to arbitrary lengths. However, as the diameters of the first, second, and third rollers  2 A,  2 B, and  2 C are larger, the feed of the material per rotation of each of the rollers  2 A,  2 B, and  2 C can be made correspondingly larger, and therefore the material feed speed can be made greater. 
     It is desirable that the first, second, and third rollers  2 A,  2 B, and  2 C have mold releasability with respect to a stack of prepreg P which is a material of the filler F. In fact, the mold releasability was checked using as materials aluminum having a ceramic coating for providing durability and non-stickiness for the prepreg P, aluminum coated with a fluorine resin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyurethane, polytetrafluoroethylene (PTFE), and nylon 6,6 (a polyamide whose molecule structure is represented by {CO—(CH 2 ) 4 —CO—NH—(CH 2 ) 6 —NH} n ). The results confirmed that the aluminum having a ceramic coating for giving non-stickiness and durability are good in both durability and mold releasability. 
     Therefore, from the viewpoint of securing durability and mold releasability with respect to the prepreg P, ceramic-coated metals are preferable as materials of the rollers  2 A,  2 B, and  2 C. Hence, it is desirable that at least one of the three rollers  2 A,  2 B, and  2 C be formed from a metal coated with a ceramic that has non-stickiness and durability. 
     A rotation mechanism  3  is an apparatus for rotating the first, second, and third rollers  2 A,  2 B, and  2 C. Therefore, in the rotation mechanism  3 , a first bearing  5 A for holding a first rotation shaft  4 A of the first roller  2 A, a second bearing  5 B for holding a second rotation shaft  4 B of the second roller  2 B, and a third bearing  5 C for holding a third rotation shaft  4 C of the third roller  2 C can be provided on a stand  6 . 
     The first bearing  5 A has such a structure that the first rotation shaft  4 A protruding from both sides of the cylindrical or hollow cylindrical first roller  2 A are held at two side, that is, both sides of the first roller  2 A. The second bearing  5 B and the third bearing  5 C have such structures as to hold a second rotation shaft  4 B of the circular disc-shaped second roller  2 B and a third rotation shaft  4 C of the circular disc-shaped third roller  2 C at predetermined inclination angles. 
     It is desirable that the first bearing  5 A, the second bearing  5 B, and the third bearing  5 C be sealed type angular ball bearings. That is, it is desirable that the three rollers  2 A,  2 B, and  2 C be constructed so as to be rotated in sealed type angular ball bearings. The angular ball bearings are bearings capable of withstanding loads in the radial directions and axial directions. Therefore, if angular ball bearings are used, loads applied diagonally from the rollers  2 A,  2 B, and  2 C can be withstood. Furthermore, employment of sealed type angular ball bearings prevents leakage of lubricating oil. 
     Because of being able to avoid the use of a lubricating oil, oilless bushes were used as bearings to perform shaping tests. It was revealed that the bearings become fixed due to the loads from the rollers  2 A,  2 B, and  2 C. It was also revealed that a radial ball bearing that receives loads in radial directions, when used, cannot sufficiently bear loads that are obliquely applied. Therefore, sealed type angular bearings capable of preventing leakage of a lubricating oil and withstanding obliquely applied loads are suitable as the first bearing  5 A, second bearing  5 B, and the third bearing  5 C. 
     The rotation mechanism  3  further includes motors  7 A,  7 B, and  7 C for producing rotating power for rotation shafts  4 A,  4 B, and  4 C of the first, second, and third rollers  2 A,  2 B, and  2 C. Therefore, the first, second, and third rollers  2 A,  2 B, and  2 C rotate automatically, independently of an operator&#39;s manual operation, so that a round bar-shaped stack of prepreg P as a material is fed out by friction forces occurring between the prepreg P and the first, second, and third rollers  2 A,  2 B, and  2 C. 
     Output shafts of the motors  7 A,  7 B, and  7 C may be provided so as to be coaxial with the rotation shafts  4 A,  4 B, and  4 C of the first, second, and third rollers  2 A,  2 B, and  2 C or may also be provided so as not to be coaxial with the rotation shafts  4 A,  4 B, and  4 C. In the case where the output shafts of the motors  7 A,  7 B, and  7 C are provided so as to be coaxial with the rotation shafts  4  of the rollers  2 , a power transmission mechanism for transmitting rotating powers output from the output shafts of the motors  7  to the rotation shafts  4  of the rollers  2  is provided. 
     In the example illustrated in  FIG. 1 , the output shaft of the first motor  7 A is directly coupled to the rotation shaft  4 A of the cylindrical or hollow cylindrical first roller  2 A. Specifically, the rotation shaft  4 A of the first roller  2 A and the output shaft of the first motor  7 A are disposed so as to align on a straight line. Therefore, motive power can be transmitted directly from the output shaft of the first motor  7 A to the rotation shaft  4 A of the first roller  2 A so as to automatically rotate the first roller  2 A. 
     On the other hand, the second motor  7 B for producing rotating power for the rotation shaft  4 B of the circular disc-shaped second roller  2 B and the third motor  7 C for producing rotating power for the rotation shaft  4 C of the circular disc-shaped third roller  2 C are disposed at such positions that the output shafts of the motors  7 B and  7 C are parallel to but not collinear with the rotation shafts  4 B and  4 C, respectively. 
       FIG. 6  is a view of the second roller  2 B, the second motor  7 B, and a power transmission mechanism for transmitting motive power from the second motor  7 B to the second roller  2 B illustrated in  FIG. 1  which has been taken from a direction A. 
     As illustrated in  FIG. 6 , in the case where the output shaft  10  of the second motor  7 B and the rotation shaft  4 B of the second roller  2 B are not on the same straight line, a power transmission mechanism  11  for transmitting rotating power from the second motor  7 B to the rotation shaft  4 B of the second roller  2 B can be constructed of pulleys  11 A and  11 B and a power transmission belt  11 C. 
     Concretely, the first pulley  11 A may be provided on the output shaft  10  of the second motor  7 B and the second pulley  11 B may be provided on the rotation shaft  4 B of the second roller  2 B. Then, the first pulley  11 A provided on the output shaft  10  of the second motor  7 B and the second pulley  11 B provided on the rotation shaft  4 B of the second roller  2 B are connected by the power transmission belt  11 C so that rotating power can be transmitted from the second motor  7 B to the rotation shaft  4 B of the second roller  2 B. 
     Of course, the power transmission mechanism  11  does not necessarily need to be constructed of the pulleys  11 A and  11 B and the power transmission belt  11 C but can instead be constructed of other desired components such as a gear train or sprockets engaged with a chain. A power transmission mechanism for transmitting rotating power from the third motor  7 C to the rotation shaft  4 C of the third roller  2 C can also be constructed similarly to the power transmission mechanism  11  for transmitting rotating power from the second motor  7 B to the rotation shaft  4 B of the second roller  2 B. 
     The rotation shafts  4 A,  4 B, and  4 C of the first, second, and third rollers  2 A,  2 B, and  2 C receive rotating power from the first, second, and third motors  7 A,  7 B, and  7 C, respectively. Therefore, the first, second, and third rollers  2 A,  2 B, and  2 C are rotated by the rotating power from the first, second, and third motors  7 A,  7 B, and  7 C. 
     However, the first, second, and third motors  7 A,  7 B, and  7 C are controlled so that the rotation speed (number of rotations per unit time) of the first roller  2 A for shaping the flat surface of the filler F and the rotation speed of the second and third rollers  2 B and  2 C for shaping the curved surfaces of the filler F are different from each other. That is, a rotation speed different is intentionally provided between the first roller  2 A and the second and third rollers  2 B and  2 C. In this case, the first motor  7 A is controlled so as to rotate the rotation shaft  4 A of the first roller  2 A at a first rotation speed while each of the second and third motors  7 B and  7 C is controlled so that each of the rotation shafts  4 B and  4 C of the second and third rollers  2 B and  2 C is rotated at a second rotation speed that is different from the first rotation speed. 
     Therefore, as illustrated as an example in  FIG. 1 , a control unit  20  for overall control of the first, second, and third motors  7 A,  7 B, and  7 C may be provided according to need. 
     The control unit  20  controls the rotation speeds of the first, second, and third motors  7 A,  7 B, and  7 C by outputting, to the first, second, and third motors  7 A,  7 B, and  7 C, control values of the rotation speeds of their output shafts. The control unit  20  can be constructed of circuits, including an electronic circuit such as a computer that includes an input unit  20 A, memory unit  20 B, and a computation unit  20 C, an analog-to-digital (A/D) converter  20 D, etc. 
     Of course, instead of the control unit  20 , an operating person may adjust the outputs of the first, second, and third motors  7 A,  7 B, and  7 C. Since the rotation speeds of the output shafts of the first, second, and third motors  7 A,  7 B, and  7 C are adjusted by an operating person or the control unit  20 , the first, second, and third motors  7 A,  7 B, and  7 C are variable-output motors. 
     Next, a method for determining the first rotation speed of the first roller  2 A and the second rotation speed of the second and third rollers  2 B and  2 C will be described. 
       FIG. 7  illustrates advantageous effects that are achieved by providing a rotation speed difference among the first, second, and third rollers  2 A,  2 B, and  2 C illustrated in  FIG. 1 .  FIG. 8  is a right side view of the first and second rollers  2 A and  2 B illustrated in  FIG. 7 . 
     As illustrated in  FIG. 7 , the first roller  2 A for shaping the flat surface of the filler F has a simple hollow cylindrical structure or a simple cylindrical structure. Therefore, the first roller  2 A has a uniform radius r 1 . Therefore, as indicated in  FIG. 8 , when the first roller  2 A is rotated at a constant angular velocity to shape the flat surface of the filler F, the speed v 1  of an outer surface of the first roller  2 A is constant at any position in the direction of the first axis AX 1 . That is, the first roller  2 A is in contact with the stack of prepreg P and the filler F at the constant speed v 1 . 
     On the other hand, the second and third rollers  2 B and  2 C for shaping the round surfaces of the filler F have a circular disc-shaped structure whose outer periphery has a curved surface that corresponds to the round surfaces of the filler F. Concretely, as indicated in  FIG. 7 , a vertical sectional shape of the second and third rollers  2 B and  2 C has an arc that corresponds to the round surfaces of the filler F. 
     Therefore, the radius r 2  of the second roller  2 B changes depending on position in the direction of the second axis AX 2 . Hence, as indicated in  FIG. 8  the speed v 2  of the outer surface of the second roller  2 B is constant. Concretely, since the speed v 2  of the outer surface of the second roller  2 B is proportional to the radius r 2  of the second roller  2 B, the speed v 2  of the outer surface has a maximum value v 2 _max at the position at which the radius r 2  of the second roller  2 B has a maximum value r 2 _max and the speed v 2  of the outer surface has a minimum value v 2 _min at the position at which the radius r 2  of the second roller  2 B has a minimum value r 2 _min. Therefore, the second roller  2 B contacts the filler F, with the speed v 2  varying over a distribution range. This applies to the third roller  2 C as well. 
     Because of the facts, for instance, that the speeds of the surfaces of the first, second, and third rollers  2 A,  2 B, and  2 C which are in contact with the filler F are not constant, and that the amounts of deformation of the stack of prepreg P caused by the first roller  2 A and the second and third rollers  2 B and  2 C are different from each other, and also that the amount of sliding between the first roller  2 A and the stack of prepreg P is different from the amount of sliding between the second and third rollers  2 B and  2 C and the stack of prepreg P, shaped fillers F sometimes have wrinkles formed thereon. 
     In fact, the shaping of a filler F performed by rotating the first, second, and third rollers  2 A,  2 B, and  2 C at the same rotation speed in conditions that the radius r 1  of the first roller  2 A was equal to the maximum value r 2 _max of the radii r 2  of the second and third rollers  2 B and  2 C confirmed that it is sometimes the case that wrinkles are formed on the entire filler F and, furthermore, a filler F temporarily warps upward and then droops by its own weight after passing the first, second, and third rollers  2 A,  2 B, and  2 C. 
     A cause for the upward warpage of the filler F is considered to be that the speed v 2  of the second and third rollers  2 B and  2 C in contact with the filler F reaches a minimum value v 2 _min at a summit of the filler F formed as a boundary between the two curved surfaces. Wrinkles can be considered to be formed as prepregs P near the surfaces are dragged rearward by portions of the second and third rollers  2 B and  2 C which are in contact with the filler F and low in the speed v 2 . 
     However, the distribution of the amount of slip of surface prepreg P is not proportional to the distribution of the radius r 2  of the second and third rollers  2 B and  2 C and the distribution of the speed v 2 . Therefore, it is speculated that causes for wrinkles also include the resistance to slip between layers of prepregs P and non-uniform slide of the filler F with respect to the first, second, and third rollers  2 A,  2 B, and  2 C. 
     With regard to this issue, it is possible to set a difference between the first rotation speed of the first roller  2 A and the second rotation speed of the second and third rollers  2 B and  2 C so as to reduce the factors that cause wrinkles and deformation, such as the factor that the speed v 2  of the second and third rollers  2 B and  2 C in contact with the filler F is not constant, the factor that sliding occurs between the filler F and the first, second, and third rollers  2 A,  2 B, and  2 C, the factor that the amount of deformation caused on the stack of prepreg P differs between the first roller  2 A and the second and third rollers  2 B and  2 C, etc. 
     An appropriate rotation speed difference between the first rotation speed of the first roller  2 A and the second rotation speed of the second and third rollers  2 B and  2 C can be determined by a shaping test on a filler F. In order to inhibit formation of wrinkles, it is important that an average speed v 2  of portions of the second and third rollers  2 B and  2 C which are in contact with the filler F be kept not excessively high or not excessively low in comparison with the speed v 1  of the outer surface of the first roller  2 A which is in contact with the filler F. Therefore, in the case where the radius r 1  of the first roller  2 A is equal to the maximum value r 2 _max of the radius r 2  of each of the second and third rollers  2 B and  2 C, the second rotation speed of the second and third rollers  2 B and  2 C is set to a greater value than the first rotation speed of the first roller  2 A unless there is a special condition. 
     The distribution of the speed v 2  on the outer periphery of the second and third rollers  2 B and  2 C changes with the angle between the first axis AX 1  of the first roller  2 A and each of the second and third axes AX 2  and AX 3  of the second and third rollers  2 B and  2 C. Furthermore, the amounts of sliding between the first, second, and third rollers  2 A,  2 B, and  2 C and the post and pre-shaping stacks of prepregs P is considered to change with shaping conditions such as the material of prepregs P, the temperature at which the stack of prepreg P is loaded with pressures, and the humidity at which the stack of prepreg P is loaded with pressures. 
     A filler F having a different thickness can be shaped if the second and third rollers  2 B and  2 C are replaced with rollers that differ from the second and third rollers  2 B and  2 C in the radii thereof measured at end portions of vertical sections thereof, the end portions serving to shape the curved surfaces of a filler F that correspond to round corners. In this case, the distribution of the speed v 2  on the outer periphery of the second and third rollers  2 B and  2 C changes also with the radius of each of the second and third rollers  2 B and  2 C measured at the end portion of a vertical section thereof. 
     Therefore, conditions for making the rotation speeds of the first roller  2 A and the second and third rollers  2 B and  2 C different from each other can be determined beforehand separately for shaping conditions by tests. For instance, tests are performed by varying shaping conditions, such as the materials of prepregs P, the temperature at which the stack of prepreg P is loaded with pressures, the humidity at which the stack of prepreg P is loaded with pressures, the angle between the first axis AX 1  of the first roller  2 A and each of the second and third axes AX 2  and AX 3  of the second and third rollers  2 B and  2 C, and the radii of each of the circular disc-shaped second and third rollers  2 B and  2 C measured at the end portion of a vertical section thereof, so that appropriate rotation speed differences between the first rotation speed of the first roller  2 A and the second rotation speed of the second and third rollers  2 B and  2 C can be obtained separately for each of the shaping conditions. 
     This makes it possible to determine appropriate rotation speed differences between the first rotation speed of the first roller  2 A and the second rotation speed of the second and third rollers  2 B and  2 C in relation to actual shaping conditions. As a concrete example, an appropriate rotation speed difference between the first rotation speed and the second rotation speed can be determined in relation to at least one of the material of prepregs P, the temperature at which the stack of prepreg P is loaded with pressures, the humidity at which the stack of prepreg P is loaded with pressures, the angle between the first axis AX 1  of the first roller  2 A and each of the second and third axes AX 2  and AX 3  of the second and third rollers  2 B and  2 C, or the radii of each of the circular disc-shaped second and third rollers  2 B and  2 C measured at the end portion of a vertical section of each roller. 
     Appropriate rotation speed differences between the first rotation speed and the second rotation speed for each of the shaping conditions can be saved in the memory unit  20 B. As a practical example, a table that indicates relations between shaping conditions and appropriate rotation speed differences between the first rotation speed and the second rotation speed may be saved in the memory unit  20 B. 
     Then, if information for specifically determining shaping conditions is input to the computation unit  20 C from the input unit  20 A, the computation unit  20 C can obtain an appropriate preset rotation speed difference between the first rotation speed and the second rotation speed by referring to the memory unit  20 B. Then, the control unit  20  can set, in the computation unit  20 C, control values of the rotation speeds of the first, second, and third motors  7 A,  7 B, and  7 C so that the first roller  2 A and the second and third rollers  2 B and  2 C will rotate with the rotation speed difference obtained with reference to the memory unit  20 B, and then can output, from the computation unit  20 C, control signals that represent of the thus set control values of the rotation speeds to the first, second, and third motors  7 A,  7 B, and  7 C, via circuits such as the A/D converter  20 D. That is, the control unit  20  can automatically control the first, second, and third motors  7 A,  7 B, and  7 C and also the first, second, and third rollers  2 A,  2 B, and  2 C on the basis of preset values of appropriate rotation speed differences between the first rotation speed and the second rotation speed. 
     The composite shaping apparatus  1  and the composite shaping method as described above are designed so as to provide a rotation speed difference between the shaping first roller  2 A and the shaping second and third rollers  2 B and  2 C that clamp the stack of prepreg P. 
     Advantageous Effects 
     Due to the features described above, the composite shaping apparatus  1  and the composite shaping method can prevent or reduce the wrinkles and warpage formed on the filler F that is a stack of prepreg P that has been shaped. As a result, the quality of the filler F can be improved. It has been confirmed that a filler F with restrained wrinkling and/or warpage has been restrained can actually be manufactured by providing an appropriate rotation speed difference between the first roller  2 A and the second and third rollers  2 B and  2 C. 
     Second Embodiment 
       FIG. 9  is a configuration diagram of a composite shaping apparatus according to a second embodiment of the disclosure. 
     A composite shaping apparatus  1 A in the second embodiment illustrated in  FIG. 9  differs from the composite shaping apparatus  1  in the first embodiment in that the composite shaping apparatus  1 A does not include second and third motors  7 B and  7 C for rotating second and third rollers  2 B and  2 C. Other configurations and operations of the composite shaping apparatus  1 A of the second embodiment are substantially not different from those of the composite shaping apparatus  1  of the first embodiment. The same configurations as those in the first embodiment and configurations that correspond to those in the first embodiment are denoted by the same reference characters in the diagram and will not be described below. 
     The composite shaping apparatus  1 A is provided with a first motor  7 A that rotates a rotation shaft  4 A of a first roller  2 A. The second and third rollers  2 B and  2 C is not provided with a motor  7  that transmits rotating power to rotation shafts  4 B and  4 C of the second and third rollers  2 B and  2 C. Therefore, the composite shaping apparatus  1 A is constructed so that the second and third rollers  2 B and  2 C are configured by friction force occurring between the second and third rollers  2 B and  2 C and the prepreg P, instead of the rotating power transmitted from the motor  7  to the rotation shafts  4 B and  4 C. 
     Specifically, the composite shaping apparatus  1 A of the second embodiment is configured so that the cylindrical or hollow cylindrical first roller  2 A whose surface in contact with a prepreg P has a constant speed v 1  is rotated by the first motor  7 A while the circular disc-shaped second and third rollers  2 B and  2 C whose surfaces in contact with the prepreg P have varying speeds v 2  are rotated by friction force that occur between the surfaces and the prepreg P. 
     Therefore, the composite shaping apparatus  1 A of the second embodiment can also provide a rotation speed difference between the first roller  2 A and the second and third rollers  2 B and  2 C. In particular, the second and third rollers  2 B and  2 C can be rotated without a need to overcome friction force that occurs between the rollers  2 B and  2 C and the prepreg P. Therefore, the amount of sliding between the second and third rollers  2 B and  2 C and the prepreg P can be reduced. As a result, the wrinkles and warpage that can occur on the filler F can be prevented or reduced, so that the quality of the filler F can be improved. 
     Furthermore, since the motor  7  is made up of only the first motor  7 A, the configuration of the composite shaping apparatus  1 A can be simplified and the electric power consumption can be reduced. 
     Note that, as described above in conjunction with the first embodiment, the appropriate rotation speed difference between the first roller  2 A and the second and third rollers  2 B and  2 C changes with shaping conditions. Therefore, it can be determined according to the shaping conditions whether to rotate the second and third rollers  2 B and  2 C by giving rotating power from the second and third motors  7 B and  7 C to the rotation shafts  4 B and  4 C of the second and third rollers  2 B and  2 C as in the first embodiment or to rotate the second and third rollers  2 B and  2 C by friction force that occurs between the second and third rollers  2 B and  2 C and the prepreg P without transmitting rotating power from the motor  7  to the rotation shafts  4 B and  4 C of the second and third rollers  2 B and  2 C as in the second embodiment. 
     Specifically, besides the rotation speeds of the first, second, and third rollers  2 A,  2 B, and  2 C, the presence/absence of rotating power transmitted to the rotation shafts  4 A,  4 B, and  4 C of the first, second, and third rollers  2 A,  2 B, and  2 C can also be determined according to at least one of the material of prepregs P, the temperature at which the stack of prepreg P is loaded with pressure, the humidity at which the stack of prepreg P is loaded with pressure, the angle between the first axis AX 1  of the first roller  2 A and each of the second and third axes AX 2  and AX 3  of the second and third rollers  2 B and  2 C, or the radii of each of the circular disc-shaped second and third rollers  2 B and  2 C measured at the end portion of a vertical section thereof. 
     It is to be noted that the composite shaping apparatus  1  of the first embodiment can also rotate the second and third rollers  2 B and  2 C only by the friction force produced between the second and third rollers  2 B and  2 C and the prepreg P by switching off the electric power supply for the second and third motors  7 B and  7 C. Therefore, the use of the composite shaping apparatus  1  of the first embodiment makes it possible to switch between the rotation of the second and third rollers  2 B and  2 C driven by the second and third motors  7 B and  7 C and the rotation of the rollers  2 B and  2 C by friction force between the rollers  2 B and  2 C and the prepreg P, according to the shaping conditions. 
     Third Embodiment 
       FIG. 10  is a configuration diagram of a composite shaping apparatus according to a third embodiment of the disclosure. 
     A composite shaping apparatus  1 B of the third embodiment illustrated in  FIG. 10  is different from the composite shaping apparatus  1  of the first embodiment in that the composite shaping apparatus  1 B of the third embodiment includes two roller units  30 A and  30 B each of which is made up of first, second, and third rollers  2 A,  2 B, and  2 C. Other configurations and operations of the composite shaping apparatus  1 B of the third embodiment are substantially not different from those of the composite shaping apparatus  1  of the first embodiment. Therefore,  FIG. 10  illustrates only the rollers  2  and a motor  7 . The same configurations as and the configurations that correspond to those of the composite shaping apparatus  1  described above are denoted by the same reference characters and will not be described below. 
     In the composite shaping apparatus  1 B of the third embodiment, the first roller unit  30 A and the second roller unit  30 B are disposed at different positions in the feeding direction of the stack of prepreg P and the filler F. 
     The first roller unit  30 A is made up of first, second, and third rollers  2 A_ 1 ,  2 B_ 1 , and  2 C_ 1  as a plurality of subsidiary rollers disposed at such positions as to clamp a bar-shaped stack of prepreg P at a front position. More concretely, the first roller unit  30 A is made up of a cylindrical or hollow cylindrical first roller  2 A_ 1  that rotates about a first axis AX 1  and two circular disc-shaped rollers, that is, second and third rollers  2 B_ 1  and  2 C_ 1 , that rotate about second and third axes AX 2  and AX 3  that are inclined with respect to the first axis AX 1  and mutually symmetric with respect to a plane perpendicular to the first axis AX 1 . The first, second, and third rollers  2 A_ 1 ,  2 B_ 1 , and  2 C_ 1 , which are a first plurality of rollers that constitute the first roller unit  30 A, are disposed so that a space that corresponds to a cross-sectional shape of the filler F is formed between the first, second, and third rollers  2 A_ 1 ,  2 B_ 1 , and  2 C_ 1 . 
     Therefore, rotation of the first, second, and third rollers  2 A_ 1 ,  2 B_ 1 , and  2 C_ 1  that constitute the first roller unit  30 A will feed the stack of prepreg P forward and, simultaneously, shape the filler F at a first position that is a front position in a feeding direction. 
     On the other hand, the second roller unit  30 B is made up of first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  as a plurality of subsidiary rollers that are disposed at a rear position so as to clamp the bar-shaped stack of prepreg P. More concretely, the second roller unit  30 B is made up of a second plurality of subsidiary rollers that are, in this embodiment, the cylindrical or hollow cylindrical first roller  2 A_ 2  that rotates about a first axis AX 1  and two rollers that are the circular disc-shaped second and third rollers  2 B_ 2  and  2 C_ 2  that rotate about second and third axes AX 2  and AX 3 , respectively, that are inclined with respect to the first axis AX 1  and symmetrical to each other with respect to a plane perpendicular to the first axis AX 1 . The first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  as a second plurality of subsidiary rollers that constitute the second roller unit  30 B are disposed so that a space that corresponds to a cross-sectional shape of a filler F is formed between the first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2 . 
     Therefore, rotation of the first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  that constitute the second roller unit  30 B will feed the stack of prepreg P forward and, simultaneously, shape the filler F at a second position that is different from and in rear of the first position in the feeding direction. 
     The first, second, and third rollers  2 A_ 1 ,  2 B_ 1 , and  2 C_ 1  that constitute the first roller unit  30 A are rotated by the rotating power transmitted from the first, second, and third motors  7 A_ 1 ,  7 B, and  7 C. Specifically, the first, second, and third motors  7 A_ 1 ,  7 B, and  7 C rotate the first, second, and third rollers  2 A_ 1 ,  2 B_ 1 , and  2 C_ 1  by transmitting rotating power to rotation shafts  4 A_ 1 ,  4 B_ 1 , and  4 C_ 1  of the first, second, and third rollers  2 A_ 1 ,  2 B_ 1 , and  2 C_ 1 , respectively. 
     Note that a rotation speed difference is provided between the rotation speed of the first roller  2 A_ 1  and that of the second and third rollers  2 B_ 1  and  2 C_ 1 . Concretely, the first motor  7 A_ 1  is configured to rotate the rotation shaft  4 A_ 1  of the first roller  2 A_ 1  at a first rotation speed v_m. On the other hand, the second and third motors  7 B and  7 C are configured to rotate the rotation shafts  4 B_ 1  and  4 C_ 1  of the second and third rollers  2 B_ 1  and  2 C_ 1 , respectively, at a second rotation speed v_h that is faster than the first rotation speed v_m. 
     Therefore, the first roller unit  30 A has substantially the same configuration and functions as the composite shaping apparatus  1  of the first embodiment. Therefore, formation of wrinkles and warpage on the filler F shaped by the first roller unit  30 A can be restrained. 
     Of the first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  that constitute the second roller unit  30 B, the second and third rollers  2 B_ 2  and  2 C_ 2  are configured to be rotated by friction force that occurs between the rollers  2 B_ 2  and  2 C_ 2  and the prepreg P, not by the rotating power transmitted from the motor  7  to rotation shafts  4 B_ 2  and  4 C_ 2  of the second and third rollers  2 B_ 2  and  2 C_ 2 . Therefore, the first roller  2 A_ 2  is connected to a motor  7 A_ 2  that rotates the first roller  2 A_ 2  by transmitting rotating power to a rotation shaft  4 A_ 2  of the first roller  2 A_ 2 . In contrast, the rotation shafts  4 B_ 2  and  4 C_ 2  of the second and third rollers  2 B_ 2  and  2 C_ 2  are not connected to the motor  7 . 
     Therefore, the second roller unit  30 B has substantially the same configuration and functions as the composite shaping apparatus  1 A of the second embodiment. Hence, the filler F shaped by the second roller unit  30 B is also substantially prevented from having wrinkles and warpage. 
     Furthermore, a rotation speed difference can also be provided between the rotation speed of the first roller unit  30 A and the second roller unit  30 B. Specifically, while the rotation shaft  4 A_ 1  of the first roller  2 A_ 1  that constitutes the first roller unit  30 A is rotated at the first rotation speed v_m by rotational driving of the first motor  7 A_ 1 , the rotation shaft  4 A_ 2  of the first roller  2 A_ 2  that constitutes the second roller unit  30 B can be rotated at a third rotation speed v_ 1  that is slower than the first rotation speed v_m by rotational driving of the motor  7 A_ 2 . That is, the first roller unit  30 A and the second roller unit  30 B can be controlled so that the rotation speed of the first roller unit  30 A disposed at a side near the outlet of the stack of prepreg P is greater than the rotation speed of the second roller unit  30 B disposed at a side near the inlet of the stack of prepreg P. 
     Then, tensile force is produced in the filler F between the first roller unit  30 A and the second roller unit  30 B. Therefore, slackening of the filler F between the first roller unit  30 A and the second roller unit  30 B can be prevented. This makes it possible to inhibit deformation of the filler F and shape the filler F more linearly. 
     If tensile force can be produced in the filler F between the first roller unit  30 A and the second roller unit  30 B, it is also possible to cause the rotating power from the motor  7  to act on all of the first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  that constitute the second roller unit  30 B. Note that if the second and third rollers  2 B_ 2  and  2 C_ 2  that constitute the second roller unit  30 B are configured so as not to be rotated by the motor  7  as illustrated in  FIG. 10 , the configuration of the composite shaping apparatus  1 B can be simplified and, at the same time, tensile force can be produced in the filler F between the first roller unit  30 A and the second roller unit  30 B. 
     That is, if sufficiently large motive power is given to the first roller unit  30 A that is disposed on a feeding side, it often becomes possible to achieve both the feeding of the filler F and production of tensile force. Therefore, the configuration example illustrated in  FIG. 10  is one of preferable configurations from the viewpoint of reduction of electric power consumption achieved by the simplified configuration and the reduced number of motors  7  and of improvement of quality achieved by the retained linearity of the filler F after shaping. 
     In the case where two sets of roller units  30 A and  30 B are disposed as illustrated in  FIG. 10 , the rotation speed difference between the rollers  2  and the presence/absence of rotating power given to the rollers  2  can be set. Specifically, the rotation speed difference between the rollers  2  and the presence/absence of rotating power given to the rollers  2  can be set according to, for example, at least one of the material of prepregs P, the temperature at which stack of prepreg P is loaded with pressure, the humidity at which the stack of prepreg P is loaded with pressure, the inclination angles of the circular disc-shaped second and third rollers  2 B_ 1 ,  2 C_ 1 ,  2 B_ 2 , and  2 C_ 2 , or the radii of the circular disc-shaped second and third rollers  2 B_ 1 ,  2 C_ 1 ,  2 B_ 2 , and  2 C_ 2  measured at end portions of vertical sections of the rollers. 
       FIG. 11  illustrates a left side view of the first roller unit  30 A illustrated in  FIG. 10 .  FIG. 12  illustrates a left side view of the second roller unit  30 B illustrated in  FIG. 10 . 
     In the case where the two roller units  30 A and  30 B are used to shape a filler F, the inclination angles of the circular disc-shaped second and third rollers  2 B_ 1 ,  2 C_ 1 ,  2 B_ 2 , and  2 C_ 2  can be made different between the roller units  30 A and  30 B. As a concrete example, in the first roller unit  30 A, the angles θ 1  and θ 2  at which the circular disc-shaped second and third rollers  2 B_ 1  and  2 C_ 1  pressed against the cylindrical or hollow cylindrical first roller  2 A_ 1  can be set to 60 degrees as illustrated in  FIG. 11 . In the second roller unit  30 B, on the other hand, the angles θ 1  and θ 2  at which the circular disc-shaped second and third rollers  2 B_ 2  and  2 C_ 2  are pressed against the cylindrical or hollow cylindrical first roller  2 A_ 2  can be set to 36.87 degrees as illustrated in  FIG. 12 . 
     As described above in conjunction with the first embodiment, when the angles θ 1  and  02  at which the circular disc-shaped second and third rollers  2 B and  2 C are pressed against the first roller  2 A is set to the 36.87 degrees, the stack of prepreg P can be uniformly loaded with a compression force. When the angles θ 1  and θ 2  at which the circular disc-shaped rollers  2 B and  2 C are pressed against the first roller  2 A is set to 60 degrees, the flatness of the lower surface of the filler F can be improved. 
     Therefore, the second roller unit  30 B that loads the round bar-shaped stack of prepreg P with pressure can uniformly apply compression force to the stack of prepreg P. This will improve quality within the filler F. Furthermore, because the filler F shaped by the second roller unit  30 B is further shaped by the first roller unit  30 A, the flatness of the lower surface of the filler F can be improved. 
     As can be understood from the foregoing description, the composite shaping apparatus  1 B of the third embodiment includes the two roller units  30 A and  30 B whose rotation speeds can be adjusted is capable of providing rotation speed differences not only between the rollers  2  that together clamp the stack of prepreg P but also between the roller units  30 A and  30 B that separately clamp the stack of prepreg P at different positions. Therefore, the composite shaping apparatus  1 B of the third embodiment achieves substantially the same advantageous effects as those achieved by the composite shaping apparatus  1  of the first embodiment and further achieves an advantageous effect of further improving the linearity of the shaped filler F by producing tension in the stack of prepreg P. 
     Furthermore, because the angles at which the circular disc-shaped second and third rollers  2 B and  2 C are pressed against the first roller  2 A can be set to appropriate angles different between the roller units  30 A and  30 B, the quality of the shaped filler F can be further improved. Concretely, both uniformity within the filler F and flatness of the lower surface of the filler F can be improved. 
     Fourth Embodiment 
       FIG. 13  is a configuration diagram of a composite shaping apparatus according to a fourth embodiment of the disclosure. 
     A composite shaping apparatus  1 C of the fourth embodiment illustrated in  FIG. 13  differs from the composite shaping apparatus  1 B of the third embodiment in that a first roller  2 A_ 1  that constitutes a first roller unit  30 A and a first roller  2 A_ 2  that constitutes a second roller unit  30 B are provided with a rotation speed difference and rotated by a single common first motor  7 A. Other configurations and operations of the composite shaping apparatus  1 C of the fourth embodiment are substantially not different from those of the composite shaping apparatus  1 B of the third embodiment. Therefore,  FIG. 13  illustrates only rollers  2  and motors  7 . The same configurations as and configurations that correspond to those of the apparatus  1 B described above are denoted by the same reference characters and will not be described below. 
     As illustrated in  FIG. 13 , the composite shaping apparatus  1 C can be configured so that rotating power from the common first motor  7 A is transmitted to both the first roller  2 A_ 1  that constitutes the first roller unit  30 A and the first roller  2 A_ 2  that constitutes the second roller unit  30 B. 
     As a concrete example, an output shaft of the first motor  7 A can be coaxially connected to an end of a rotation shaft  4 A_ 1  of the first roller  2 A_ 1  that constitutes the first roller unit  30 A. A third pulley  40 A can be fixed to the other end of the rotation shaft  4 A_ 1  of the first roller  2 A_ 1  that constitutes the first roller unit  30 A. An end of a rotation shaft  4 A_ 2  of the first roller  2 A_ 2  that constitutes the second roller unit  30 B which is on the same side as the end of the rotation shaft  4 A_ 1  provided with the fixed third pulley  40 A can be provided with a fixed fourth pulley  40 B. 
     The third pulley  40 A fixed to the rotation shaft  4 A_ 1  of the first roller  2 A_ 1  that constitutes the first roller unit  30 A and the fourth pulley  40 B fixed to the rotation shaft  4 A_ 2  of the first roller  2 A_ 2  that constitutes the second roller unit  30 B can be interconnected by a power transmission belt  40 C. Incidentally, the example illustrated in  FIG. 13  includes a fifth pulley  40 D that applies a pressing force to the power transmission belt  40 C from its outer side in order to maintain a tension of the power transmission belt  40 C. 
     Thus, the third pulley  40 A, the fourth pulley  40 B, the power transmission belt  40 C, and the fifth pulley  40 D constitute a power transmission mechanism  40  that transmits rotating power from the first motor  7 A to both the rotation shaft  4 A_ 1  of the first roller  2 A_ 1  that constitutes the first roller unit  30 A and the rotation shaft  4 A_ 2  of the first roller  2 A_ 2  that constitutes the second roller unit  30 B. 
     The diameter of the third pulley  40 A fixed to the first roller  2 A_ 1  of the first roller unit  30 A and the diameter of the fourth pulley  40 B fixed to the first roller  2 A_ 2  of the second roller unit  30 B may be different from each other. This makes it possible for the common first motor  7 A to rotate the first roller  2 A_ 1  of the first roller unit  30 A and the first roller  2 A_ 2  of the second roller unit  30 B at different rotation speeds v_m and V_ 1 . That is, the first roller  2 A_ 1  of the first roller unit  30 A and the first roller  2 A_ 2  of the second roller unit  30 B can be given a rotation speed difference. 
     More concretely, when the diameter of the fourth pulley  40 B fixed to the first roller  2 A_ 2  of the second roller unit  30 B is larger than the diameter of the third pulley  40 A fixed to the first roller  2 A_ 1  of the first roller unit  30 A, the rotation speed v_ 1  of the first roller  2 A_ 2  of the second roller unit  30 B is made slower than the rotation speed v_m of the first roller  2 A_ 1  of the first roller unit  30 A. 
     Therefore, it becomes possible to feed out the filler F with tension occurring in the filler F between the first roller  2 A_ 1  of the first roller unit  30 A and the first roller  2 A_ 2  of the second roller unit  30 B. This will prevent the shaped filler F from having wrinkles or warpage. 
     The ratio between the rotation speeds v_m and v_ 1  of the two first rollers  2 A_ 1  and  2 A_ 2  is equal to the ratio between the lengths of the circumferences of the third pulley  40 A and the fourth pulley  40 B. Therefore, an appropriate difference or ratio between the diameters of the third pulley  40 A and the fourth pulley  40 B can be determined beforehand by a shaping test. Therefore, the difference between the rotation speeds v_m and v_ 1  can always be provided as a fixed ratio, despite changes in the rotation speed of the first motor  7 A. 
     Of course, the power transmission mechanism  40  do not necessarily need to be constructed of the pulleys  40 A,  40 B, and  40 D and the power transmission belt  40 C but can instead be constructed of other desired components such as a gear train or sprockets engaged with a chain. In that case, too, it is appropriate to construct the power transmission mechanism  40  on a shaping test so that an appropriate rotation speed difference or rotation speed ratio will be provided between the two first rollers  2 A_ 1  and  2 A_ 2 . 
     The foregoing composite shaping apparatus  1 C of the fourth embodiment is configured so that the two first rollers  2 A_ 1  and  2 A_ 2  that constitute the two roller units  30 A and  30 B are rotated by the common first motor  7 A. Therefore, the composite shaping apparatus  1 C of the fourth embodiment achieves substantially the same advantageous effects as the composite shaping apparatus  1 B of the third embodiment and further achieves advantageous effects of further reducing the number of motors  7  and facilitating the control of the motors  7 . 
     Of course, the composite shaping apparatus  1 C can be configured so as to rotate not only the first rollers  2 A_ 1  and  2 A_ 2  but a plurality of arbitrary rollers  2  by using a common motor  7 . In particular, a plurality of rollers  2  whose rotation axes are parallel can be easily configured to be driven by a common motor  7  through the use of a power transmission made up of a belt, pulleys, etc. 
     Fifth Embodiment 
       FIG. 14  is a configuration diagram of a composite shaping apparatus according to a fifth embodiment of the disclosure. 
     A composite shaping apparatus  1 D of the fifth embodiment illustrated in  FIG. 14  differs from the composite shaping apparatus  1 B of the third embodiment in that none of first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  that constitute the second roller unit  30 B is provided with a motor  7  for producing rotating power. Other configurations and operations of the composite shaping apparatus  1 D of the fifth embodiment are substantially not different from those of the composite shaping apparatus  1 B of the third embodiment. Therefore, FIG.  14  illustrates only the rollers  2  and the motor  7 . The same configurations as and configurations that correspond to those of the apparatus  1 B described above are denoted by the same reference characters and will not be described below. 
     As illustrated in  FIG. 14 , all the first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  that constitute the second roller unit  30 B may be rotated by utilizing friction force produced with prepregs P, instead of using a motor  7  from which rotating power is transmitted to the first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2 . That is, it is permissible that while the first roller unit  30 A is given rotating powers produced by first, second, and third motors  7 A,  7 B, and  7 C, the second roller unit  30 B be rotated by friction force produced with the prepregs P, without rotating power transmitted from a motor. 
     In this case, the rotation speeds of the first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  can be adjusted by adjusting the friction resistance produced with respect to rotation of the first, second, and third rollers  2 A_ 2 ,  2 B_ 2 , and  2 C_ 2  that constitute the second roller unit  30 B. 
     In the composite shaping apparatus  1 D of the fifth embodiment configured in this manner, tensile force can be produced in the filler F between the first roller unit  30 A and the second roller unit  30 B. Therefore, similar to the composite shaping apparatus  1 B of the third embodiment, the composite shaping apparatus  1 D of the fifth embodiment can further improve the linearity of the shaped filler F. Furthermore, the composite shaping apparatus  1 D of the fifth embodiment allows the number of motors  7  to be reduced, in comparison with the composite shaping apparatus  1 B of the third embodiment. 
     Sixth Embodiment 
       FIG. 15  is a configuration diagram of a composite shaping apparatus according to a sixth embodiment of the disclosure. 
     A composite shaping apparatus  1 E of the sixth embodiment illustrated in  FIG. 15  differs from the composite shaping apparatus  1 B of the third embodiment in that the apparatus  1 E is configured to provide a rotation speed difference between rollers  2  by making the roller diameters different. Other configurations and operations of the composite shaping apparatus  1 E of the sixth embodiment are substantial not different from those of the composite shaping apparatus  1 B of the third embodiment. Therefore,  FIG. 15  illustrates only rollers  2  and motors  7 . The same configurations as and configurations that correspond to those of the apparatus  1 B of the third embodiment are denoted by the same reference characters and will not be described below. 
     Although the third to fifth embodiments have been described above on the precondition that the first roller  2 A_ 1  of the first roller unit  30 A and the first roller  2 A_ 2  of the second roller unit  30 B have the same diameter, the diameter of the first roller  2 A_ 1  of the first roller unit  30 A and the diameter of the first roller  2 A_ 2  of the second roller unit  30 B may be different from each other as illustrated in  FIG. 15 . 
     In this case, a surface of the first roller  2 A_ 1  of the first roller unit  30 A and a surface of the second roller  2 A_ 2  of the second roller unit  30 B that are in contact with a prepreg P can be moved at different speeds even when the rotation speed of the first roller  2 A_ 1  of the first roller unit  30 A and the rotation speed of the first roller  2 A_ 2  of the second roller unit  30 B are the same. More concretely, making the roller diameter of the first roller  2 A_ 2  of the second roller unit  30 B larger than the roller diameter of the first roller  2 A_ 1  of the first roller unit  30 A as illustrated in  FIG. 15  will make it possible to make the moving speed of the surface of the first roller  2 A_ 2  of the second roller unit  30 B that is in contact with the prepreg P slower than the moving speed of the surface of the first roller  2 A_ 1  of the first roller unit  30 A that is in contact with the prepreg P even when the rotation speeds of the two first rollers  2 A_ 1  and  2 A_ 2  are equal to a rotation speed v_m. 
     This makes it possible to feed out the filler F while producing tension in the filler F between the first roller  2 A_ 1  of the first roller unit  30 A and the first roller  2 A_ 2  of the second roller unit  30 B. As a result, it becomes possible to prevent the shaped filler F from having wrinkles or warpage. 
     The ratio between the moving speeds of the surfaces of the two first rollers  2 A_ 1  and  2 A_ 2  is equal to the ratio between the roller diameters of the first rollers  2 A_ 1  and  2 A_ 2 . Therefore, an appropriate difference or ratio between the roller diameters of the first rollers  2 A_ 1  and  2 A_ 2  can be determined beforehand by a shaping test. 
     Furthermore, the difference or ratio between the maximum diameters of the first rollers  2 A_ 1  and  2 A_ 2  and the second and third rollers  2 B_ 1 ,  2 C_ 1 ,  2 B_ 2 , and  2 C_ 2  that clamp the filler F can also be appropriately determined beforehand by a shaping test. 
     In the composite shaping apparatus  1 E of the sixth embodiment configured as described above, a tensile force can be produced in the filler F between the first roller unit  30 A and the second roller unit  30 B. Therefore, similar to the composite shaping apparatus  1 B of the third embodiment, the composite shaping apparatus  1 E of the sixth embodiment can also further improve the linearity of the shaped filler F. 
     Furthermore, the composite shaping apparatus  1 E of the sixth embodiment can improve the quality of the filler F by producing a tensile force in the filler F, without a need to control the motors  7 . Therefore, the composite shaping apparatus  1 E can be constructed by using a simple arrangement of the motors  7  and a circuit. It is also permissible that the moving speeds of the surfaces of the rollers  2  be made roughly suitable by appropriately determining the maximum roller diameters of the rollers  2  and that the moving speed of the surfaces of the rollers  2  be finely adjusted by controlling the motors  7 . 
     Seventh Embodiment 
       FIG. 16  is a configuration diagram of a composite shaping apparatus according to a seventh embodiment of the disclosure. 
     A composite shaping apparatus  1 F of the seventh embodiment illustrated in  FIG. 16  differs from the composite shaping apparatuses  1 ,  1 A,  1 B,  1 C,  1 D, and  1 E of the first to sixth embodiments in that the apparatus  1 F shapes the filler F by using two rollers  2 D and  2 E. Other configurations and operations of the composite shaping apparatus  1 F of the seventh embodiment are substantially not different from those of the composite shaping apparatuses  1 ,  1 A,  1 B,  1 C,  1 D, and  1 E of the first to sixth embodiments. Therefore,  FIG. 16  illustrates only the rollers  2 D and  2 E, and the same configurations as and configurations that correspond to those of the apparatuses described above will not be described below. 
     As illustrated in  FIG. 16 , in the composite shaping apparatus  1 F of the seventh embodiment, a bar-shaped stack of prepreg P that is a material of a filler F is clamped by the two cylindrical or hollow cylindrical first and second rollers  2 D and  2 E, and a surface of one of the two cylindrical or hollow cylindrical rollers  2 D and  2 E is provided with a recess that corresponds to a cross-sectional shape of the filler F. In the example illustrated in  FIG. 16 , the first roller  2 D is disposed at an upper side and provided with a recess that corresponds a cross-sectional shape of the filler F, and the second roller  2 E is disposed at a lower side and provided with no recess and with a uniform diameter. The first roller  2 D and the second roller  2 E are disposed at such positions as to clamp the bar-shaped stack of prepreg P. 
     In this embodiment, a speed difference can be provided between the rotation speeds of the first roller  2 D and the second roller  2 E as in the first embodiment. Alternatively, the second roller  2 E can be rotated by the motor  7  while the first roller  2 D is rotated by the friction force with the prepreg P, as in the second embodiment. Furthermore, as in the third to sixth embodiments, two roller units each constructed of a first roller  2 D and a second roller  2 E can be disposed. Furthermore, the maximum roller diameters of the first roller  2 D and the second roller  2 E that clamp the stack of prepreg P can be made different from each other. 
     The composite shaping apparatus  1 F of the seventh embodiment described above, compared with the composite shaping apparatuses  1 ,  1 A,  1 B,  1 C,  1 D, and  1 E of the first to sixth embodiment, has a fewer rollers  2  and therefore allows the configuration and control of the composite shaping apparatus  1 F to be simplified. 
     Other Embodiments 
     While specific embodiments of the disclosure have been described, it is to be noted that the foregoing embodiments are mere illustrative and not intended to limit the scope of the disclosure. The novel methods and apparatuses described herein can be embodied in various modes other than those described above. The modes of the methods and apparatuses described herein can be subjected to various changes and modifications, including omissions and replacements in various manners, without departing from the gist of the disclosure. It is to be understood that what are described in the appended claims and their equivalents are encompassed in the scope and gist of the disclosure and include various modes and modifications. 
     For instance, features of the composite shaping apparatuses  1 ,  1 A,  1 B,  1 C,  1 D,  1 E, and  1 F of the foregoing embodiments can be combined with one another. Conversely, one or more features of any one of the composite shaping apparatuses  1 ,  1 A,  1 B,  1 C,  1 D,  1 E, and  1 F can be omitted. Specifically, a composite shaping apparatus can be constructed of at least one first roller that loads a stack of prepreg P with pressure, at least one second roller that loads the stack of prepreg P with pressure, and a motor that rotates at least one of the first roller or the second roller. Furthermore, a shaped prepreg P can be manufactured by rotating at least one of the at least one first roller or the at least one second roller provided in the composite shaping apparatus through the use of the motor and therefore loading the prepreg P with pressure while feeding the prepreg P by the first roller and the second roller. Then, it is possible to rotate the first roller and the second roller with difference made between the two roller in at least one of friction resistance to rotation, rotation speed, roller diameter, or the presence/absence of rotating power. This will reduce the wrinkles and warpage that can occur on the prepreg P. 
     Furthermore, although in the foregoing embodiments, vertical sections of the circular disc-shaped rollers have arc shapes, circular disc-shaped rollers whose vertical sections do not have arc shapes may also be used. As a concrete example, a composite shaping apparatus may also be constructed by using circular disc-shaped rollers whose vertical sections have at their ends the shape of a curve whose curvature is not constant, such as a logarithmic spiral, as described and illustrated in the claims, specification, and drawings of Japanese Patent Application No. 2016-31792. In such a case, the composite shaping apparatus may be provided with an angle adjustment mechanism that continuously changes the inclination angles of the rotation axes of circular disc-shaped rollers. 
     In the case where the inclination angles of the rotation axes of circular disc-shaped rollers are changed during the shaping of a filler F, the rotation speeds of the circular disc-shaped rollers can also be changed in accordance with the inclination angles of the rotation axes of the circular disc-shaped roller during the shaping. This makes possible the high-quality shaping of a filler F whose cross sections are not uniform. In particular, use of circular disc-shaped rollers whose vertical sections have at their end portions the shape of a part of logarithmic spiral allows the high-quality shaping of a filler F whose thickness varies over the length. 
     Furthermore, some fillers F have cross-sectional shapes that are not axially symmetric. In a concrete example, when a filler F is mounted on a surface that is not perpendicular to the direction of the height of the filler F, the cross-sectional shape of the filler F is not axially symmetric. When a filler F whose cross-sectional shape is not axially symmetric is to be shaped, the shapes and arrangement of the first, second, and third rollers  2 A,  2 B, and  2 C can be determined beforehand in accordance with the shape of the filler F. As a concrete example, the first axis AX 1  of the first roller  2 A may be set in a direction that is not horizontal, in accordance with the shape of the filler F. Furthermore, the angles θ 1  and θ 2  of the direction in which the circular disc-shaped second roller  2 B and third roller  2 C are pressed against with respect to the surface of the first roller  2 A may be set to mutually different angles in accordance with the shape of the filler F. Further, the radii of a circumferential surface of the circular disc-shaped second roller  2 B and the radii of a circumferential surface of the third roller  2 C may be set to mutually different lengths in accordance with the shape of the filler F.