Abstract:
Helical winding is reliably carried out in a plurality of patterns at different angles in a short period of time. A filament winding apparatus for winding fiber bundles onto the surface of a mandrel includes a helical winding head for use in helical winding of the fiber bundles onto the mandrel. The helical winding head includes at least two guide arrays, each including a plurality of guide portions disposed along a circumferential direction of the mandrel, and a repositioning mechanism capable of repositioning the guide portions by rotating each guide array relative to another.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to filament winding methods and apparatuses for winding fiber bundles onto the surface of a rotating mandrel, thereby manufacturing a pressure tank or suchlike. 
         [0003]    2. Description of the Background Art 
         [0004]    The filament winding apparatus is an apparatus for manufacturing hollow containers, such as pressure tanks, pipes, and the like. The filament winding apparatus winds fiber bundles onto a mandrel (a liner) to manufacture a product (a pressure tank or suchlike). The fiber bundle is made up of a fiber material consisting of, for example, a glass fiber and synthetic resin. 
         [0005]    In general, the filament winding apparatus manufactures a product by winding fiber bundles by means of both hoop winding ((a) of  FIG. 3 ) and helical winding ((b) and (c) of  FIG. 3 ), thereby making a plurality of layers (e.g., ten layers of more) of fiber bundles (see Japanese Laid-Open Patent Publication No. 10-119138). During the hoop winding, the fiber bundles are wound roughly perpendicular to the axial direction of the mandrel, whereas during the helical winding, the fiber bundles are wound at a predetermined angle with respect to the axial direction of the mandrel. Typically, the filament winding apparatus sequentially winds a small number of fiber bundles (e.g., ten bundles or less) onto the rotating mandrel to cover the mandrel surface with the fiber bundles. 
         [0006]    Incidentally, in some cases, for example, to enhance product strength, the helical winding is carried out to form a plurality of layers in a plurality of patterns at different angles with respect to the axial direction of the mandrel. Conventionally, the filament winding apparatus winds a small number of fiber bundles onto the mandrel, and therefore when carrying out the helical winding in a plurality of patterns, product manufacturing takes a significant amount of time. Although the manufacturing time can be shortened by winding wider fiber bundles onto the mandrel, the wider fiber bundles slip on a mirrored portion of the mandrel, resulting in a product of inferior quality. Therefore, filament winding apparatuses that wind a layer of fiber bundles at one time during the helical winding have been proposed (see Japanese Laid-Open Patent Publication Nos. 2002-283467 and 2004-314550). Such filament winding apparatuses are capable of winding a layer of fiber bundles with a single winding operation, but they have difficulty in forming helical winding layers, such that fiber bundles in each layer are uniformly arranged in such a manner as to leave no space therebetween. 
       SUMMARY OF THE INVENTION 
       [0007]    Therefore, in view of the foregoing, the problem to be solved by the present invention is to provide a filament winding apparatus capable of reliably carrying out helical winding in a plurality of patterns at different angles in a short period of time. 
         [0008]    To solve the above problem, the present invention provides a filament winding method for use in helical winding of a plurality of fiber bundles onto a mandrel, wherein a layer of fiber bundles is wound onto the mandrel at one time during the helical winding, and an apparent number of fiber bundles to be wound is changed in accordance with a winding angle. The present invention also provides a filament winding apparatus for winding fiber bundles onto a surface of a mandrel, the apparatus comprising a helical winding head for use in helical winding of a plurality of fiber bundles onto the mandrel, wherein the helical winding head includes: at least two guide arrays, each including a plurality of guide portions disposed along a circumferential direction of the mandrel; and a repositioning mechanism capable of repositioning the guide portions by rotating each guide array relative to another. 
         [0009]    It is preferable that the guide arrays are guide ring members extending in the circumferential direction of the mandrel, and the guide portions are guide holes made along the guide ring members. 
         [0010]    It is preferable that the repositioning mechanism is capable of creating two interchangeable states, such that, in one state, the guide portions of the guide arrays are positioned at regular intervals in the circumferential direction of the mandrel, whereas in the other state, the guide portions are each aligned with one guide portion of the other guide in the circumferential direction of the mandrel. 
         [0011]    It is preferable that the filament winding apparatus further comprises a hoop winding head for use in hoop winding of the fiber bundles onto the mandrel, wherein the hoop winding head includes: a bobbin for supplying the fiber bundles to the mandrel; and a mechanism for rotating the bobbin along the circumferential direction of the mandrel. 
         [0012]    It is preferable that the filament winding apparatus further comprises a controller portion for allowing the helical winding of the fiber bundles by rotating the mandrel, as well as allowing the hoop winding of the fiber bundles by rotating the bobbin of the hoop winding head. 
         [0013]    As described above, in the filament winding apparatus according to the present invention, the helical winding head includes the at least two guide arrays, each including a plurality of guide portions disposed along the circumferential direction of the mandrel, and the repositioning mechanism capable of repositioning the guide portions by rotating each guide array relative to another. Therefore, with the guide portions, a plurality of fiber bundles can be wound onto the mandrel at one time during the helical winding, thereby making it possible to shorten the manufacturing time. In addition, the repositioning mechanism simply repositions each guide array to a predetermined position, thereby making it possible to carry out the helical winding in a plurality of patterns at different angles. Thus, the helical winding can be readily carried out in a plurality of patterns, resulting in superior productivity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view illustrating a filament winding apparatus. 
           [0015]      FIG. 2  is a perspective view illustrating a winder portion. 
           [0016]      FIG. 3  is a side view illustrating a hoop winding and helical windings. 
           [0017]      FIG. 4  is a perspective view illustrating enlarged representations of a guide ring portion. 
           [0018]      FIG. 5  is a front view illustrating a helical winding head. 
           [0019]      FIG. 6  is a perspective view illustrating a bundle spreading guide. 
           [0020]      FIG. 7  is a diagram for describing a repositioning mechanism, in which (a) is an exploded perspective view of the guide ring portion, and (b) is a cross-sectional side view of a portion of the guide ring portion. 
           [0021]      FIG. 8  is an enlarged side view illustrating a fiber bundle R wound by means of helical winding. 
           [0022]      FIG. 9  is a side view illustrating the winding operation of the filament winding apparatus during hoop winding. 
           [0023]      FIG. 10  is a side view illustrating the winding operation of the filament winding apparatus during helical winding (with a winding angle of θ 1 ). 
           [0024]      FIG. 11  is a side view illustrating the winding operation of the filament winding apparatus during the helical winding (with a winding angle of θ 2 ). 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    Hereinafter, a filament winding apparatus according to the present invention will be described in detail with reference to the accompanying drawings. 
         [0026]    First, the structure of the filament winding apparatus will be described.  FIG. 1  is a perspective view illustrating the filament winding apparatus.  FIG. 2  is a perspective view illustrating a winder portion. 
         [0027]    As shown in  FIG. 1 , the filament winding apparatus includes a winder portion  1 , and a supplier portion  2 . The winder portion  1  winds fiber bundles R onto a mandrel M. The supplier portion  2  includes creel supporters  21 , each being provided with a plurality of creels  20 . The creels  20  each hold a wound fiber bundle R. 
         [0028]    The fiber bundles R are each made up of a fiber material consisting of, for example, a glass fiber and synthetic resin. The supplier portion  2  supplies the fiber bundle R unwound from each creel  20  to the winder portion  1 . 
         [0029]    The fiber bundles R have been previously impregnated with a thermosetting synthetic resin material. Note that, in some cases, the fiber bundles R are not impregnated with any resin. In such cases, a resin impregnation device (not shown) is provided between the winder portion  1  and the supplier portion  2  in order to apply resin to the fiber bundles R unwound from the creels  20  before they are supplied to the winder portion  1 . 
         [0030]    As shown in  FIG. 2 , the winder portion  1  includes a machine frame  10 . The machine frame  10  includes a pair of parallel first guide rails  10   a  extending in its longitudinal direction  1   a.  The winder portion  1  includes a mandrel holder  11  provided on the machine frame  10 . The mandrel holder  11  is capable of reciprocating along the first guide rails  10   a  in the longitudinal direction  1   a.    
         [0031]    The mandrel holder  11  includes a spindle S extending in the longitudinal direction  1   a.  The mandrel holder  11  rotatably supports the spindle S with spindle rotation shafts  11   a  provided at its opposite ends. The spindle rotation shafts  11   a  are configured to rotate the spindle S about its central axis. 
         [0032]    In the case of manufacturing a pressure tank, the mandrel M is made up of high-strength aluminum, metal, resin or the like, and shaped to have a cylindrical portion Ma and domed portions Mb provided at its opposite ends ( FIG. 3 ). The spindle S removably secures the mandrel M. The mandrel M is secured to the spindle S along the central axis. Accordingly, the longitudinal direction  1   a  of the machine frame  10  coincides with an axial direction M 1  of the mandrel M. Note that the material, shape, etc., of the mandrel M can be changed product by product. 
         [0033]    The winder portion  1  includes a hoop winding head  12  and a helical winding head  13 . The hoop winding head  12  winds the fiber bundles R onto the mandrel M by means of hoop winding. The helical winding head  13  winds the fiber bundles R onto the mandrel M by means of helical winding. 
         [0034]      FIG. 3  is a side view illustrating a hoop winding and helical windings. During the hoop winding, the fiber bundles R are wound roughly perpendicular to the axial direction M 1  of the mandrel M as shown in (a) of  FIG. 3 , whereas during the helical winding, the fiber bundles R are wound at a predetermined angle with respect to the axial direction M 1  of the mandrel M as shown in (b) and (c) of  FIG. 3 . 
         [0035]    As shown in  FIG. 2 , the winder portion  1  includes a controller portion  14 . The controller portion  14  controls the start, stop, and speed of reciprocating movement of the mandrel holder  11 , as well as the start, stop, and speed of rotation of the mandrel M via the spindle rotation shafts  11   a . Furthermore, the controller portion  14  controls the start, stop, and speed of reciprocating movement of the hoop winding head  12 , as well as the start, stop, and speed of circulating movement of bobbins  12   b.    
         [0036]    As shown in  FIG. 2 , the hoop winding head  12  includes a hoop winding head body  12   a.  The hoop winding head body  12   a  has a passage hole  12   d  disposed in its center. The hoop winding head  12  allows the mandrel M to pass therethrough via the passage hole  12   d.    
         [0037]    The machine frame  10  includes a pair of parallel second guide rails  10   b  extending in the longitudinal direction  1   a.  The hoop winding head body  12   a  is capable of reciprocating along the second guide rails  10   b  in the longitudinal direction  1   a.  Thus, the hoop winding head  12  can reciprocate in the longitudinal direction  1   a  of the machine frame  10 , with the mandrel M passing through the passage hole  12   d.    
         [0038]    The hoop winding head  12  includes a plurality (in the present embodiment, two) of bobbins  12   b  for holding wound fiber bundles R. The hoop winding head body  12   a  has a guiding groove  12   c  provided outside the passage hole  12   d  along a circumferential direction M 2  of the mandrel M. The bobbins  12   b  circulate along the guiding groove  12   c,  so that the fiber bundles R coming out of the circulating bobbins  12   b  are wound onto the mandrel M. 
         [0039]    The helical winding head  13  includes a helical winding head body  13   a.  The helical winding head body  13   a  has a passage hole  13   d  disposed in its center. The helical winding head  13  allows the mandrel M to pass therethrough via the passage hole  13   d.    
         [0040]    The helical winding head body  13   a  is secured to the machine frame  10 . Reciprocating movement of the mandrel holder  11  allows the helical winding head  13  to reciprocate relatively oppositely in the longitudinal direction  1   a,  with the mandrel M passing through the passage hole  13   d.    
         [0041]    The helical winding head  13  winds the fiber bundles R unwound from the supplier portion  2  onto the mandrel M. The helical winding head body  13   a  has an annular guide ring portion  15  extending around the passage hole  13   d  along the circumferential direction M 2  of the mandrel M. The helical winding head body  13   a  has tension-creating members  13   b  opposed to each other with respect to the guide ring portion  15 . The helical winding head  13  has guide rollers  13   c  opposed to each other with respect to the helical winding head body  13   a.    
         [0042]    With the guide rollers  13   c,  the helical winding head  13  guides the fiber bundles R unwound from the creels  20  to the tension devices  13   b.  The tension devices  13   b  apply predetermined tension to the fiber bundles R. The predetermined tension applied to the fiber bundles R by the tension devices  13   b  allows the fiber bundles R to be securely wound onto the mandrel M. The guide ring portion  15  guides the fiber bundles R to the mandrel M. 
         [0043]      FIG. 4  is a perspective view illustrating enlarged representations of the guide ring portion. As shown in  FIG. 4 , the guide ring portion  15  consists of a first guide ring member  150  and a second guide ring member  151 , which are shaped in the same annular form. The first guide ring member  150  and the second guide ring member  151  are in contact with each other in the longitudinal direction  1   a  of the machine frame  10  (the axial direction M 1  of the mandrel M). 
         [0044]    The first and second guide ring members  150  and  151  have a plurality of guide holes  15   a  provided along a circumferential direction  1   b  of the guide ring portion  15 . The circumferential direction  1   b  of the guide ring portion  15  coincides with the circumferential direction M 2  of the mandrel M. 
         [0045]    The guide holes  15   a  are directed to the center of the guide ring portion  15 . The guide ring portion  15  guides the fiber bundles R to the mandrel M while passing each fiber bundle R through a corresponding one of the guide holes  15   a . The first and second guide ring members  150  and  151  have the same number of guide holes  15   a  provided at regular intervals. 
         [0046]      FIG. 5  is a front view illustrating the helical winding head  13 . As shown in  FIG. 5 , the helical winding head  13  includes a plurality of ring-like auxiliary guides  13   e.  The auxiliary guides  13   e  are arranged outside the guide ring portion  15  along the circumferential direction  1   b  of the guide ring portion  15 . 
         [0047]    The fiber bundles R unwound from the creels  20  are supplied from opposite sides of the helical winding head  13  through the guide rollers  13   c  to the tension devices  13   b . The fiber bundles R are guided from the tension devices  13   b  through the auxiliary guides  13   e  to the guide holes  15   a  in the guide ring portion  15 . 
         [0048]      FIG. 6  is a perspective view illustrating a bundle spreading guide. As shown in  FIG. 6 , the guide ring portion  15  has provided on its inside the bundle spreading guide  16  per guide hole  15   a.  The bundle spreading guide  16  has a pair of bundle spreading rollers  16   a  rotatably provided thereto. The bundle spreading rollers  16   a  are provided in parallel to each other in the diametrical direction of the guide hole  15   a . The bundle spreading guide  16  includes a rotating base  16   b  capable of rotating about the center of the guide hole  15   a . The rotating base  16   b  supports the bundle spreading rollers  16   a.    
         [0049]    The bundle spreading guide  16  is configured to pass the fiber bundle R between the pair of bundle spreading rollers  16   a.  Therefore, even if the angle is changed at which to wind the fiber bundle R onto the mandrel M, the bundle spreading guide  16  can rotate to freely change its direction to wind the fiber bundle R onto the mandrel M, with the fiber bundle R being spread by the bundle spreading rollers  16   a  (i.e., the width of the fiber bundle becomes wider). 
         [0050]      FIG. 7  is a diagram for describing a repositioning mechanism, in which (a) is an exploded perspective view of the guide ring portion, and (b) is a cross-sectional side view of a portion of the guide ring portion. As shown in  FIG. 7 , the guide ring portion  15  has a connection ring  152  provided around its outer circumference, such that the connection ring  152  is disposed on both the first and second guide ring members  150  and  151  to connect them together. 
         [0051]    The connection ring  152  is secured to the second guide ring member  151 . The connection ring  152  extends along the circumferential direction  1   b  of the guide ring portion  15  ((a) of  FIG. 7 ), and has a rail portion  152   a  protruding toward the inside of the first guide ring member  150  ((b) of  FIG. 7 ). The first guide ring member  150  has a guiding groove  152   b  externally provided along the circumferential direction  1   b  ((b) of  FIG. 7 ). 
         [0052]    The first guide ring member  150  is secured to the helical winding head body  13   a.  The rail portion  152   a  of the connection ring  152  firmly attached to the second guide ring member  151  engages the guiding groove  152   b  provided in the first guide ring member  150 . As a result, the second guide ring member  151  rotationally slides in the circumferential direction  1   b  with respect to the first guide ring member  150 . 
         [0053]    The guide ring portion  15  includes a repositioning mechanism  17 . The repositioning mechanism  17  allows the second guide ring member  151  to rotate by a predetermined angle with respect to the first guide ring member  150 . The repositioning mechanism  17  has two semispherical concave recesses  17   a  provided in a contact surface  150   a  of the first guide ring member  150  that is in contact with the second guide ring member  151 . 
         [0054]    Furthermore, the repositioning mechanism  17  has a ball  17   b  provided in a contact face  151   a  of the second guide ring member  151  that is in contact with the first guide ring member  150 , and the ball  17   b  can be fitted in the recesses  17   a.  The ball  17   b  can emerge from/recoil into the contact face  151   a  of the second guide ring member  151  in accordance with expansion/contraction of a compression spring  17   c.    
         [0055]    When the compression spring  17   c  contracts, the ball  17   b  recoils to allow rotation of the second guide ring member  151 . On the other hand, when the compression spring  17   c  expands, the ball  17   b  engages one of the recesses  17   a,  so that the second guide ring member  151  is fixed in one of two shift positions, thereby allowing the guide ring portion  15  to shift between first and second states. 
         [0056]    The distance L 2  between the recesses  17   a  is half the distance L 1  between two adjacent guide holes  15   a  ((a) of  FIG. 7 ). When the guide ring portion  15  is in the first state, each guide hole  15   a  in the second guide ring member  151  faces an intermediary position between two adjacent guide holes  15   a  in the first guide ring member  150  as shown in (a) of  FIG. 4 . Specifically, in the circumferential direction  1   b , each center line  150   b,  which theoretically extends in the diametrical direction  1   a  of its one corresponding guide hole  15   a  in the first guide ring member  150  (the diametrical direction being identical to the longitudinal direction  1   a ), is equally distanced from two adjacent center lines  151   b , each theoretically extending in the diametrical direction  1   a  of its one corresponding guide hole  15   a  in the second guide ring member  151 . 
         [0057]    Furthermore, when the guide ring portion  15  is in the second state, each guide hole  15   a  of the first guide ring member  150  is aligned with one of the guide holes  15   a  in the second guide ring member  151  as shown in (b) of  FIG. 4 . Specifically, in the circumferential direction  1   b,  each center line  150   b,  which theoretically extends in the diametrical direction  1   a  of its one corresponding guide hole  15   a  in the first guide ring member  150 , overlaps with one of the center lines  151   b,  each theoretically extending in the diametrical direction  1   a  of its one corresponding guide hole  15   a  in the second guide ring member  151 . 
         [0058]      FIG. 8  is an enlarged side view illustrating a fiber bundle R wound by means of helical winding. As shown in  FIG. 8 , the fiber bundle R wound by means of helical winding is inclined at a predetermined angle (winding angle) of θ with respect to the axial direction M 1  of the mandrel M. The winding angle of θ can be changed variously in accordance with, for example, mechanical strength required by the product. 
         [0059]    Here, for each fiber bundle R, if the dimension (width) in the direction perpendicular to a length direction R 1  is W, the dimension (perimeter section) in the circumferential direction M 2  of the mandrel M is A, and the winding angle is θ, the following equation (1) is established. 
         [0000]        A=W/cos θ   (1) 
         [0060]    For the mandrel M, if the radius is r, and the dimension (entire perimeter) in the circumferential direction M 2  is B, the following equation (2) is established. 
         [0000]      B=2πr   (2) 
         [0061]    Accordingly, in the case of covering the mandrel M with one layer of fiber bundles R, if the number of fiber bundles R that are to be arranged in parallel to each other without any overlap (and space) in the circumferential direction M 2  of the mandrel M is n, the following equation (3) can be established in accordance with the above equations (1) and (2). 
         [0000]        n=B/A =(2π r ·cos θ)/ W    (3) 
         [0062]    The helical winding head  13  is capable of covering the entire perimeter of the mandrel M with the fiber bundles R at one time. Here, the term “one time” refers to a single operation in which the head  13  traverses the mandrel M from one end to the other as shown in  FIG. 10 . In addition, the helical winding head  13  is capable of carrying out the helical winding in two patterns respectively at winding angles of θ 1  ((b) of  FIG. 3 ) and θ 2  (&gt;θ 1 ) ((c) of  FIG. 3 ). 
         [0063]    According to the above equation (3), when the winding angle is θ 1 , the number of fiber bundles R that are to be arranged in parallel to each other without any overlap (and space) in the circumferential direction M 2  of the mandrel M is n 1 =(2πr·cos θ 1 )/W. In addition, when the winding angle is θ 2 , the number of fiber bundles R is n 2 =(2πr·cos θ 2 )/W. Note that the relationship between the above winding angles is such that θ 1 &lt;θ 2 , and therefore the relationship between the above numbers of fiber bundles R is such that n 1 &gt;n 2 . 
         [0064]    The guide ring portion  15  is configured as described below, such that the helical winding is carried out with the winding angle of θ 1  in the first state or with the winding angle of θ 2  in the second state. 
         [0065]    The relationship between the numbers of fiber bundles R during the helical winding is such that n 2 ×2=n 1 . That is, the winding angles of θ 1  and θ 2  are set such that the relationship n 2 ×2=n 1  is established. Moreover, the first and second guide ring members  150  and  151  each have n 2  guide holes  15   a  arranged at regular intervals. 
         [0066]    Accordingly, by bringing the guide ring portion  15  into the first state, each guide hole  15   a  in the guide ring member  150  is equally displaced from its one corresponding guide hole  15   a  in the guide ring member  151  ((a) of  FIG. 4 ), and therefore n 2 ×2(=n 1 ) guide holes  15   a  are considered to be arranged in the circumferential direction M 2  of the mandrel M. 
         [0067]    In addition, by bringing the guide ring portion  15  back into the second state, each guide hole  15   a  in the guide ring member  150  is aligned with one of the guide holes  15   a  in the guide ring member  151  ((b) of  FIG. 4 ), and therefore n 2  pairs (sets) of aligned guide holes  15   a  are considered to be arranged in the circumferential direction of the mandrel M. 
         [0068]    Therefore, in theory, when the guide ring portion  15  is in the first state, there are n 2 ×2(=n 1 ) guide holes  15   a  arranged in the circumferential direction M 2  of the mandrel M, whereas when the guide ring portion  15  is in the second state, there are n 2  pairs of aligned guide holes  15   a  arranged in the circumferential direction M 2  of the mandrel M. 
         [0069]    Thus, by bringing the guide ring portion  15  into the first state, n 2 ×2(=n 1 ) fiber bundles R are wound onto the mandrel M at one time, thereby achieving the helical winding with the winding angle of θ 1 . Furthermore, by bringing the guide ring portion  15  into the second state, n 2  pairs (sets) of fiber bundles R are wound onto the mandrel M at one time, such that the fiber bundles R in each pair are stuck together (to form two layers), thereby achieving the helical winding with the winding angle of θ 2 . 
         [0070]    Described next are winding operations of the filament winding apparatus.  FIG. 9  is a side view illustrating the winding operation of the filament winding apparatus during hoop winding. During the hoop winding, the hoop winding head  12  is controlled by the controller portion  14  as described below, so as to operate as shown in  FIG. 9 . 
         [0071]    First, the hoop winding head  12  is positioned at one end (left side in the figure; hereinafter referred to as the “left end”) of the cylindrical portion Ma of the mandrel M ((a) of  FIG. 9 ). Thereafter, two fiber bundles R unwound from their respective bobbins  12   b  are attached to the left end of the cylindrical portion Ma with adhesive tape or suchlike. At this time, the two fiber bundles R are arranged in parallel to each other without leaving any space therebetween in the axial direction M 1  of the mandrel M. 
         [0072]    Thereafter, the hoop winding head  12  moves toward the other end (right side in the figure; hereinafter, referred to as the “right end”) of the cylindrical portion Ma, while circulating the bobbins  12   b.  As a result, the two fiber bundles R are further drawn out of the bobbins  12   b . The two fiber bundles R are roughly perpendicular to (slightly inclined from) the axial direction M 1  of the mandrel M, and they are arranged in parallel to each other without any overlap and space therebetween. To achieve such an arrangement, the moving speed of the hoop winding head  12  and the circulating speed of the bobbins  12   b  are suitably determined. 
         [0073]    By moving the hoop winding head  12  from the left end of the cylindrical portion Ma ((a) of  FIG. 9 ) to the right end ((b) of  FIG. 9 ), one layer of fiber bundles R is formed on the cylindrical portion Ma. Subsequently, the hoop winding head  12  moves from the right end ((b) of  FIG. 9 ) to the left end ((a) of  FIG. 9 ). 
         [0074]    One reciprocation of the hoop winding head  12  results in two layers of fiber bundles R formed on the cylindrical portion Ma. To carry out further winding, the above-described operation is repeated a predetermined number of times. Thereafter, the fiber bundles R are cut by cutting means (not shown), thereby completing the hoop winding. 
         [0075]      FIG. 10  is a side view illustrating the winding operation of the filament winding apparatus during helical winding (with the winding angle of θ 1 ). During the helical winding (with the winding angle of θ 1 ), the mandrel holder  11  is controlled by the controller portion  14  as described below, so as to operate as shown in  FIG. 10 . 
         [0076]    First, the helical winding head  13  is positioned at the other end (right side in the figure; hereinafter, referred to as the “right end”) of the mandrel M, i.e., the end of the right-side domed portion Mb in the figure, ((a) of  FIG. 10 ). Thereafter, the guide ring portion  15  of the helical winding head  13  is brought into the first state. In the first state, n 2 ×2(=n 1 ) guide holes  15   a  are arranged at regular intervals in the guide ring portion  15  as described above. 
         [0077]    Thereafter, n 1  fiber bundles R drawn out of the guide holes  15   a  are attached with adhesive tape or suchlike to the right end of the mandrel M in the circumferential direction M 2  of the mandrel M. Subsequently, the mandrel holder  11  moves, so that the helical winding head  13  moves relatively in the opposite direction, from the right end of the mandrel M ((a) of  FIG. 10 ) to the other end (left side in the figure; hereinafter, referred to as the “left end”) ((b) of  FIG. 10 ). Simultaneously with this movement, the mandrel M is rotated via the spindle rotation shafts  11   a.    
         [0078]    The n 1  fiber bundles R are wound at the winding angle of θ 1  with respect to the axial direction M 1  of the mandrel M, such that they are arranged in parallel to each other without any overlap and space therebetween. To achieve such an arrangement, the moving speed of the helical winding head  13  (the mandrel holder  11 ) and the rotating speed of the mandrel M (the spindle rotation shafts  11   a ) are suitably determined. 
         [0079]    By moving the helical winding head  13  from the right end ((a) of  FIG. 10 ) to the left end ((b) of  FIG. 10 ), one layer of fiber bundles R is formed on the mandrel M. 
         [0080]    Subsequently, the helical winding head  13  moves from the left end ((b) of  FIG. 10 ) to the right end ((a) of  FIG. 10 ). One reciprocation of the helical winding head  13  results in two layers of fiber bundles R formed on the mandrel M. To carry out further winding, the above-described operation is repeated a predetermined number of times. 
         [0081]    Thereafter, the fiber bundles R are cut by cutting means (not shown), thereby completing the helical winding. However, in the case of subsequently carrying out helical winding with the winding angle of θ 2  or hoop winding, the winding can be immediately carried out without cutting the fiber bundles R. Specifically, in the case of subsequently carrying out the helical winding with the winding angle of θ 2 , the guide ring portion  15  is brought into the second state before carrying out an operation as described below. Alternatively, in the case of subsequently carrying out the hoop winding, the hoop winding head  12  is activated, with the helical winding head  13  being positioned at the right end of the mandrel M. 
         [0082]      FIG. 11  is a side view illustrating the winding operation of the filament winding apparatus during the helical winding (with the winding angle of θ 2 ). During the helical winding (with the winding angle of θ 2 ), the mandrel holder  11  is controlled by the controller portion  14  as described below, so as to operate as shown in  FIG. 11 . 
         [0083]    First, the helical winding head  13  is positioned at one end (right side in the figure; hereinafter, referred to as the “right end”) of the mandrel M, i.e., the end of the right-side domed portion Mb in the figure, ((a) of  FIG. 11 ). Thereafter, the guide ring portion  15  of the helical winding head  13  is brought into the second state. In the second state, n 2  pairs (sets) of guide holes  15   a  are arranged at regular intervals in the guide ring portion  15  as described above. 
         [0084]    In this case, n 2  pairs of fiber bundles R are unwound from the guide holes  15   a  (where n 2  denotes the number of pairs of fiber bundles R stuck together as described above, and the number of fiber bundles R is n 2 ×2=n 1 ). The n 2  pairs of fiber bundles R are then adhered with adhesive tape or suchlike to the right end in the circumferential direction M 2  of the mandrel M. Thereafter, the mandrel holder  11  moves, so that the helical winding head  13  moves relatively in the opposite direction, from the right end ((a) of  FIG. 11 ) to the other end (left side in the figure; hereinafter, referred to as the “left end”) ((b) of  FIG. 11 ). Simultaneously with this movement, the mandrel M is rotated via the spindle rotation shafts  11   a.    
         [0085]    The n 2  pairs of fiber bundles R are wound in parallel to each other at the winding angle of θ 2  with respect to the axial direction M 1  of the mandrel M, without any overlap and space therebetween. To achieve such an arrangement, the moving speed of the helical winding head  13  (the mandrel holder  11 ) and the rotating speed of the mandrel M (the spindle rotation shafts  11   a ) are suitably determined. 
         [0086]    By moving the helical winding head  13  from the right end ((a) of  FIG. 11 ) to the left end ((b) of  FIG. 11 ), two layers of fiber bundles R are formed on the mandrel M. Specifically, the pairs of fiber bundles R, each consisting of two fiber bundles R stuck together, are wound, so that the two layers of fiber bundles R are formed at one time. 
         [0087]    Subsequently, the helical winding head  13  moves from the left end ((b) of  FIG. 11 ) to the right end, and stops there ((a) of  FIG. 11 ). One reciprocation of the helical winding head  13  results in four layers (two layers×2) of fiber bundles R formed on the mandrel M. To carry out further winding, the above-described operation is repeated a predetermined number of times. 
         [0088]    Thereafter, the fiber bundles R are cut by cutting means (not shown), thereby completing the helical winding. However, in the case of subsequently carrying out helical winding with the winding angle of θ 1  or hoop winding, the winding can be carried out without cutting the fiber bundles R. Specifically, in the case of subsequently carrying out the helical winding with the winding angle of θ 1 , the guide ring portion  15  is brought into the first state before carrying out the above-described operation. Alternatively, in the case of subsequently carrying out the hoop winding, the hoop winding head  12  is activated, with the helical winding head  13  being positioned at the right end of the mandrel M. 
         [0089]    Note that the filament winding apparatus according to the present invention is not limited by the above embodiment, and can be configured as described below. Three or more guide ring members may be employed to carry out the helical winding in three or more patterns. Each guide array may be provided by arranging a plurality of ring-shaped guide portions. The guide portions do not have to be arranged at regular intervals. The repositioning mechanism is not limited to the above-described structure. Any mechanism can be employed so long as it can change the position of one guide array relative to another along the circumference direction of the mandrel.