Abstract:
A method of manufacturing a piston using a swaging tool includes the step of positioning a portion of a first member and a portion of a second member of the piston within a first end of an opening formed through the swaging tool, such that a reduced diameter portion of the second member is substantially aligned with a first ring portion of the first member and an end portion of the second member contacts a second ring portion of the first member to create an annular space adjacent to the first ring portion and the reduced diameter portion. The method also includes the step of subsequently swaging the first ring portion by moving the first ring portion in a direction toward a second end of the swaging tool, such that a portion of the first ring portion is positioned within the annular space to fix the first member to the second member.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to compressors, pistons for use in such compressors, and methods of manufacturing such compressors and pistons. In particular, the present invention is directed towards methods of manufacturing the piston of the compressor using a swaging tool.  
           [0003]    2. Description of Related Art  
           [0004]    Known methods of manufacturing a piston, such as the method described in Japanese Publication No. JP-A-10-159725, use a disc-shaped lid member and a cup member. The lid member forms an end surface of a piston head and the cup member includes a cylindrical portion. The bottom of the cup member is formed integrally with a connector for connecting the cup member to a swash plate. The cylindrical portion forms a peripheral surface of the piston head and has an open end, and the open end forms a brim of the cup member. The lid member closes the open end of the cylindrical portion, and a swaging tool is used to swag the brim of the cup member which forms a sealed cavity within the piston head. Specifically, the brim of the cup member is sealed to the lid member.  
         SUMMARY OF THE INVENTION  
         [0005]    Therefore, a need has arisen for a method of manufacturing a piston having a hollow head which overcome these and other short comings of the related art. A technical advantage of the present invention is that a method of manufacturing a piston is used, which reduces the cost of manufacturing the piston.  
           [0006]    According to an embodiment of the present invention, a piston is manufactured using a swaging tool. The swaging too has an opening formed therethrough. The opening comprises a first inner portion extending from a first end of the swaging tool, and an inner diameter of the first inner portion is substantially constant. The opening also comprises a second inner portion extending from a second end of the swaging tool. The second inner portion is tapered and is formed integrally with the first inner portion, such that an inner diameter of the second inner portion at the second end of the swaging tool is greater than an inner diameter of the second inner portion at the first inner portion. The piston comprises a first member, and the first member comprises a first ring portion having an outer diameter which is greater than the inner diameter of the first inner portion. The first member also comprises a second ring portion which is connected to the first ring portion, and the second ring portion has an outer diameter which is about equal to the diameter of the first inner portion. The piston also comprises a second member, and the second member comprises an end portion having an outer diameter which is about equal to an inner diameter of the second ring portion. The second member also comprises a reduced diameter portion connected to the end portion, and the reduced diameter portion has an outer diameter which is less than the outer diameter of the end portion. The method of manufacturing the piston comprises the step of positioning at least one portion of the first member within the second inner portion via the second end of the swaging tool. The method also comprises the step of positioning at least one portion of the second member within the second inner portion via the second end of the swaging tool, such that the end portion contacts the second ring portion and the reduced diameter portion is substantially aligned with the first ring portion to create an annular space adjacent to the first ring portion and the reduced diameter portion. Moreover, the method comprises the step of subsequently swaging, e.g., tapering (uniform tapering or non uniform tapering) or reducing the diameter of at least a portion of, the first ring portion by moving the first ring portion in a direction toward the first end of the swaging tool, such that at least a portion of the first ring portion is positioned within at least a portion of the annular space to fix the first member to the second member.  
           [0007]    According to another embodiment of the present invention, a piston is manufactured using a swaging method. The piston comprises a hollow piston head, and the hollow piston head comprises a first member. The first member comprises a cylindrical portion haying an outer diameter which is equal to an outer diameter of the hollow piston head, and an inner diameter which is less than the outer diameter of the hollow piston head. The cylindrical portion comprises a flange portion extending radially from an outer surface of the cylindrical portion. The piston head also comprises a second member. The second member comprises an annular groove formed therein, and at least one portion of the second member has an outer diameter which is about equal to the inner diameter of the cylindrical portion. The method of manufacturing the piston head comprises the step of positioning the at least one portion of the second member within the cylindrical portion of the first member, such that the flange portion is positioned adjacent to and, outside the annular groove. The method also comprises the step of subsequently swaging the flange portion, such that at least a portion of the flange portion is positioned within the groove to fix the first member to the second member.  
           [0008]    According, to an embodiment of the present invention, a compressor comprises a piston, and the piston of the compressor is manufactured using a swaging tool. The swaying tool has an opening formed therethrough. The opening comprises a first inner portion extending from a first end of the swaging tool, and an inner diameter of the first inner portion is substantially constant. The opening also comprises a second inner portion extending from a second end of the swaging tool. The second inner portion is tapered and is formed integrally with the first inner portion, such that an inner diameter of the second inner portion at the second end of the swaging tool is greater than an inner diameter of the second inner portion at the first inner portion. The piston comprises a first member, and the first member comprises a first ring portion having an outer diameter which is greater than the inner diameter of the first inner portion. The first member also comprises a second ring portion which is connected to the first ring portion, and the second ring portion has an outer diameter which is about equal to the diameter of the first inner portion. The piston also comprises a second member, and the second member comprises an end portion having an outer diameter which is about equal to an inner diameter of the second ring portion. The second member also comprises a reduced diameter portion connected to the end portion, and the reduced diameter portion has an outer diameter which is less than the outer diameter of the end portion. The method of manufacturing the piston comprises the step of positioning at least one portion of the first member within the second inner portion via the second end of the swaging tool. The method also comprises the step of positioning at least one portion of the second member within the second inner portion via the second end of the swaging tool, such that the end portion contacts the second ring portion and the reduced diameter portion is substantially aligned with the first ring portion to create an annular pace adjacent to the first ring portion and the reduced diameter portion. Moreover, the method comprises the step of subsequently swaging, e.g., tapering (uniform tapering or non uniform tapering) or reducing the diameter of at least a portion of, the first ring portion by moving the first ring portion in a direction toward the first end of the swaging tool, such that at least a portion of the first in a portion is positioned within at least a portion of the annular space to fix the first member to the second member.  
           [0009]    According to another embodiment of the present invention, a compressor comprises a piston, and the piston is manufactured using a swaging method. The piston comprises a hollow piston head, and the hollow piston head comprises a first member. The first diameter of the hollow piston head, and an inner diameter which is less than the outer diameter of the hollow piston head. The cylindrical portion comprises a flange portion extending radially from an outer surface of the cylindrical portion. The piston head also comprises a second member. The second member comprises an annular groove formed therein, and at least one portion of the second member has an outer diameter which is about equal to the inner diameter of the cylindrical portion. The method of manufacturing the piston head comprises the step of positioning the at least one portion of the second member within the cylindrical portion of the first member, such that the flange portion is positioned adjacent to and outside the annular groove. The method also comprises the step of subsequently swaging the flange portion, such that at least a portion of the flange portion is positioned within the groove to fix the first member to the second member.  
           [0010]    A piston manufactured using a swaging tool comprises a hollow piston head. The hollow piston head comprises a first member, and the first member, comprises a cylindrical portion. The cylindrical portion has, an outer diameter which is equal to an outer diameter of the hollow piston head, and an inner diameter which is less than the outer diameter of the hollow piston head. Moreover, the cylindrical portion comprises a flange portion extending radially from an outer surface of the cylindrical portion. The hollow piston head also comprises a second member. The second member comprises an annular groove formed therein for receiving at least a portion of the flange portion. Moreover, at least one portion of the second member has an outer diameter which is about equal to the inner diameter of the cylindrical portion.  
           [0011]    A compressor comprising a piston manufactured using a swaging tool comprises a hollow piston head. The hollow piston head comprises a first member, and the first member comprises a cylindrical portion. The cylindrical portion has an outer diameter which is equal to an outer diameter of the hollow piston head, and an inner diameter which is less than the outer diameter of the hollow piston head. Moreover the cylindrical portion comprises a flange portion extending radially from an outer surface of the cylindrical portion. The hollow piston head also comprises a second member. The second member comprises an annular groove formed therein for receiving at least a portion of the flange portion. Moreover, at least one portion of the second member has an outer diameter which is about equal to the inner diameter of the cylindrical portion.  
           [0012]    Other objects, features, and advantage will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    For a more complete understanding of the present invention, the needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawings .  
         [0014]    [0014]FIG. 1 is a cross-sectional view of a compressor having a piston manufactured by a method according to a first embodiment of the present invention.  
         [0015]    [0015]FIG. 2 is a cross-sectional view of a cup member of the piston in FIG. 1.  
         [0016]    [0016]FIG. 3 is a cross-sectional view of a lid member of the piston in FIG. 1..  
         [0017]    [0017]FIG. 4 is a cross-sectional view depicting a step of manufacturing the piston of FIG. 1.  
         [0018]    [0018]FIG. 5 is a cross-sectional view depicting another step of manufacturing the piston of FIG. 1.  
         [0019]    [0019]FIG. 6 is a partial cut away, perspective view of a modification of the lid member of FIG. 3.  
         [0020]    [0020]FIG. 7 is a cross-sectional view of a cup member manufactured by a method according to a second embodiment of the present invention.  
         [0021]    [0021]FIG. 8 is a cross-sectional view of a lid member manufactured by the method according to the second embodiment.  
         [0022]    [0022]FIG. 9 is a cross-sectional view depicting a step included in the method according to the second embodiment.  
         [0023]    [0023]FIG. 10 is a cross-sectional view depicting another step included in the method according to the second embodiment .  
         [0024]    [0024]FIG. 11 is a cross-sectional view of a lid member manufactured by a method according to a third embodiment of the present invention.  
         [0025]    [0025]FIG. 12 is a cross-sectional view of a cup member manufactured by the method according to the third embodiment.  
         [0026]    [0026]FIG. 13 is a cross-sectional view depicting a step included in the method according to the third embodiment.  
         [0027]    [0027]FIG. 14 a cross-sectional view depicting another step included in the method according to the third embodiment.  
         [0028]    [0028]FIG. 15 is a cross-sectional view of a lid member manufactured by a method according to a fourth embodiment of the present invention.  
         [0029]    [0029]FIG. 16 is a cross-sectional view of a cup member manufactured by the method according to the fourth embodiment.  
         [0030]    [0030]FIG. 17 is a cross-sectional view depicting a step included in the method according to the fourth embodiment.  
         [0031]    [0031]FIG. 18 is a cross-sectional view depicting another step included in the method according to the fourth embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]    Preferred embodiments of the present invention and their features and advantages may be understood by referring to FIGS.  1 - 18 , like numerals being used for like corresponding parts in the various drawings.  
         [0033]    Referring to FIG. 1, a compressor  50 , e.g., a swash plate, variable displacement-type compressor, may comprise a plurality of pistons  10  manufactured by a method according to a first embodiment of the present invention. Compressor  50  also may comprise a cylinder block  1 , a front housing  2 , a crank chamber  3 , and a drive shaft  4 . Specifically, cylinder block  1  may comprise a front end  1   a  and a rear end  1   b , and front housing  2  may be fixed to front end  1   a  to form crank chamber  3 . Cylinder block  1  may have a first center hole (not shown) formed therethrough, and front housing  2  may have a second center hole (not shown) formed therethrough. Cylinder block  1  and front housing  2  may support drive shaft  4  via a first radial bearing  5  positioned within the first center hole and a second radial bearing  6  positioned within the second center hole, respectively, such that drive shaft  4  may rotate. Drive shaft  4  may extend in an axial direction, such that a first end of drive shaft  4  is positioned outside front housing  2 . Moreover, a sealing member  7  may be positioned within the second center hole, such that sealing member  7  provides a seal for crank chamber  3 .  
         [0034]    Cylinder block  1  also may comprise a plurality of cylinder bores  8  formed therein, and each piston  10  may be positioned within a corresponding one of cylinder bores  8 , such that each piston  10  reciprocates independently with the corresponding one of cylinder bores  8 . The number of cylinder bores  8  may correspond to the number of pistons  10  used in compressor  50 . For example, in an embodiment, compressor  50  may comprise seven ( 7 ) pistons. Moreover, each piston  10  may comprise a cup member  100  and a lid member  110 , and cup member  100  may comprise a shoe supporter  10   a , a piston head  10   b , and a neck portion  10   c  which connects shoe supporter  10   a  to piston head  10   b . In an embodiment, cup member  100  and lid member  110  may be made from different materials, e. g., cup member  100  may be aluminum and lid member  110  may be iron. In another embodiment, cup member  100  and lid member  110  may be made from the same material e.g., aluminum.  
         [0035]    Compressor  50  also may comprise a valve plate  11 , a cylinder head  16  fixed to valve plate  11 , a suction chamber  17  formed within cylinder head  16 , and a discharge chamber  18 . formed within cylinder head  16 . Valve plate  11  may comprise a front surface  11   a  and a rear surface  11   b , and a pair of suction ports  12  and a pair of discharge ports  13  may be formed through valve plate  11 . Moreover, a plurality of suction valves  14 , e.g., a plurality of suction reed valves, may be fixed to front surface  11   a , such that suction valves  14  are positioned between piston  10  and a corresponding one of suction ports  12 . Similarly, a plurality of discharge valves  15 , e.g., a plurality of discharge reed valves, fixed to rear surface  11   b , such that discharge port  13  is positioned between piston  10  and a corresponding one of discharge valves  15 . When one of pistons  10  moves in a direction toward front housing  2 , a free end of a corresponding one of suction valves  14  and a corresponding one of discharge valves  15  also moves toward front housing  2 , such that fluid inside suction chamber  17  is drawn into a corresponding one of cylinder bores  8  via a corresponding one of suction ports  12 , and the corresponding discharge valve  15  covers a corresponding one of discharge ports  13 . Similarly, when piston  10  moves in a direction away from front housing  2 , the free end of the corresponding suction valve  14  and the corresponding discharge valve  15  moves away from front housing  2 , such that the fluid inside the corresponding cylinder bore  8  is driven into discharge chamber  18  via the corresponding discharge port  13 , and the corresponding suction valve  14  covers the corresponding suction port  12 .  
         [0036]    Compressor  50  also may comprise a swash plate  23 , and a rotor  19  positioned within crank chamber  3  and fixed to drive shaft  4  via a pin  20 . Rotor  19  also may be supported by font housing  2  via a thrust bearing  21 , and may comprise a first arm portion  19   a . A boss  22  may be mounted slidably to drive shaft  4 , such that boss  22  may be inclined relative to drive shaft  4 . Specifically, boss  22  may comprise a second arm portion  22   a  having an elongated opening  22   b  formed therethrough, such that first arm portion  19   a  may be connected to second arm portion  22   a  via a pin  19   b  positioned within elongated opening  22   b . Moreover, swash plate  23  may be fixed to boss  22 , such that when the inclination angle of boss  22  relative to drive shaft  4  is altered, the inclination angle of swash plate  23  relative to drive shaft  4  also is altered. Further, each piston  10  may be connected to swash plate  23  via a corresponding pair of shoes  24 , and shoes  24  may be supported by shoe supporter  10   a  of piston  10 , such that shoes  24  slide along an inner surface of shoe supporter  10   a.    
         [0037]    In operation, a driving source, e.g., an engine of a vehicle, rotates drive shaft  4 , swash plate  23  also rotates. Specifically, swash plate  23  slides between each pair of shoes  24 , and each pair of shoes  24  slide along the inner surface of their corresponding shoe supporter  10   a . The rotational movement of swash plate  23  may be converted into a linear reciprocating movement which may be transmitted to piston  10 . Consequently, piston  10  reciprocates within a corresponding one of cylinder bores  8 . As piston  10  reciprocates, refrigerant is drawn into the corresponding cylinder bore  8  from suction chamber  17 , and piston  10  compresses the refrigerant. The compressed refrigerant subsequently is discharged into discharge chamber  18 .  
         [0038]    Referring to FIG. 2, in this embodiment, cup member  100  may comprise a first ring portion  101 , a second ring portion  102 , and a cylindrical portion  103 . Second ring portion  102  and cylindrical portion  103  form a peripheral surface of piston head  10   b . In an embodiment, second ring portion  102  may have a thickness which is greater than a thickness of cylindrical portion  103 , and an annular groove (not shown) for receiving a piston ring (not shown) may be formed within second ring portion. In another embodiment, e.g., when the piston ring is not employed, the thickness of second ring portion  102  may be about equal to the thickness of cylindrical portion  103 . Nevertheless, in either of these embodiments, second ring portion  102  and cylindrical portion  103  may have substantially the same outer diameter measured from a center of piston head  10   b . Neck portion  10   c  may be formed integrally with cylindrical portion  103 , and may form a bottom of cup member  100 . Neck portion  10   c  also may have a recess  104  formed therein, which reduces a weight of piston  10 . Moreover, neck portion  10   c  may be formed integrally with shoe supporter  10   a , and shoe supporter  10   a  may have a pair of concave surfaces  10   a   1  and  10   a   2  formed therein, which support a corresponding pair of shoes  24 .  
         [0039]    First ring portion  101  forms a brim of cup member  100 , and has a surface  101   a  which forms an end surface of cup member  100 . An outer diameter of first ring portion  101  may be greater than the outer diameter of second ring portion  102  measured from the center of piston head  10   b . In an embodiment, an inner diameter of first ring portion  101  may be equal to the inner diameter of second ring portion  102  measured from center of piston head  10   b . In another embodiment, the inner diameter of first ring portion  101  may be greater than the inner diameter of second ring portion  102 . In yet another embodiment, the inner diameter of first ring portion  101 , may increase between second ring portion  102  and surface  101   a.    
         [0040]    Referring to FIG. 3, lid member  110  may comprise end portion  111 , e.g., a ring-shaped end portion or disc-shaped end portion, a disc portion  113 , and a reduced diameter portion  112  positioned between end portion  111  and disc portion  113 . End portion  111 , reduced diameter portion  112 , and disc portion  113  may form an annular groove  114 , and a recess  115  may be formed in end portion  111  and reduced diameter portion  112  to reduce the weight of lid member  110 . A periphery  111   a  of end portion  111  may have an outer diameter which is about equal to the inner diameter of second ring portion  102 . In this embodiment, reduced diameter portion  112  may comprise a first portion connected to end portion  111  and a second portion connected to disc portion  113 . Specifically, an outer diameter of the second portion of reduced diameter portion  112  may be constant, and an outer diameter the first portion of reduced diameter portion  112  may decrease between end portion  111  and the second portion of reduced diameter portion  112 . Moreover, disc portion  113  may have a first surface  113   a  which forms an end surface of piston head  10   b  and a second surface  113   b opposite first surface  113   a . Second surface  113   b  may be ring-shaped, and may abut surface  101   a  when end portion  111  and reduced diameter portion  112  are positioned within cup member  100 . Disc portion  113  may have a cylindrical shape, or may be tapered.  
         [0041]    Referring to FIG. 4, in this embodiment, a swaging tool  60  may comprise a first end  61 , a second end  62 , a first inner portion  64 , and a second inner portion  65 . Swaging tool  60  also may have a opening  63  formed therethrough. For example, in an embodiment, opening  63  may be a channel which divides swaging tool into a first semi-circular portion  60   a  and a second semi-circular portion  60   b . First inner portion  64  may have a constant inner diameter, e.g., may have a cylindrical-shape, and second inner portion  65  may be tapered, such that an inner diameter of second inner portion  65  may increase between first inner portion  64  and second end  62 . For example, the inner diameter of first inner portion  64  may be about equal to the outer diameter of piston head  10   b , and the inner diameter of second inner portion  65  may be greater than the inner diameter of first inner portion  64 .  
         [0042]    In an embodiment of the present invention, cup member  100  may be inserted in opening  63  from second end  62 , such that at least a portion of cylindrical portion  103  is aligned with first inner portion  64 , first ring portion  101  and second ring portion  102  are aligned with second inner portion  65 , and shoe supporter  10   a  extends beyond first end  61 . First semi-circular portion  60   a  or second semi-circular portion  60   b , or both, subsequently may be fitted to surround cylindrical portion  103 , and semi-circular portion  60   a and second semi-circular portion  60   b  then may be fixed to each other. Because semi-circular portion  60   a  and second semi-circular portion  60   b  are fixed to each other after shoe supporter  10   a  is positioned beyond first end  61 , semi-circular portion  60   a  and second semi-circular portion  60   b  may surround cylindrical portion  103  even when shoe supporter  10   a  extends beyond cylindrical portion  103  in a radial direction. Nevertheless, in another embodiment, if shoe supporter  10   a  does not extend beyond cylindrical portion  103  in a radial direction, or if piston  10  has other means for coupling piston head  10  to swash plate  23 , opening  63  may be formed, such that swaging tool  60  may be single body having the hole formed, therethrough, i.e., swaging tool  60  is not divided into first semi-circular portion  60   a  and second semi-circular portion  60   b . In this embodiment, cup member  100  simply may be inserted into opening  63  from second end  62 , such that at least a portion of cylindrical portion  103  is surrounded by first inner portion  64 .  
         [0043]    In any of the above-described embodiments, an adhesive may be applied to reduced diameter portion  112 , and end portions  111  and reduced portion  112  subsequently may be inserted into cup member  100 , such that surface  113   b  of lid member  110  contacts end surface  101   a  of first inner portion  101 , periphery  111   a  of end portion  111  contacts the inner surface of second ring portion  102 , and reduced diameter portion  112  is aligned with first ring portion  101 . Moreover, an annular space  118 , which is a portion of annular groove  114 , may be formed between first ring portion  101  and reduced diameter portion  112  when end portion  111  and reduced diameter portion  112  is inserted into cup member  100 .  
         [0044]    Referring to FIG. 5, a pushing tool  70  may be used to push cup member  100  and lid member  110  toward first end  61  of swaging tool  60 . Pushing tool  70  may comprise a disc portion  71  and a shaft portion  72  connected to the center of disc portion  71 . When lid member  110  and cup member  110  are pushed within first inner portion  64 , first inner portion  64  swags first ring portion  101  in a direction toward annular space  118 , such that at least a portion of first ring portion  101  is positioned within annular space  118  and contacts the adhesive applied to reduced diameter portion  112 . Consequently, cup member  110  may be fixed to lid member  110  without forming a gap between cup member  100  and lid member  110 .  
         [0045]    Referring to FIG. 6, in a modification of this embodiment, reduced diameter portion  112  may have a plurality of cut-off portions  116  formed therein, and first ring portion  101  may comprise a plurality of projection portions extending therefrom. For example, cut-off portions  116  may be radially spaced around reduced diameter portion  112 , and each of the projection portions may be aligned with a corresponding one of cut-off portions  116 . Specifically, first inner portion  64  may swag the projection portions into the corresponding cut-off portion  116 , such that at least a portion of each of the projection portions is positioned within corresponding cut-off portion  116 . First inner portion  64  also may swag ring portion  101  in the direction toward annular space  118 , such that at least a portion of first ring portion  101  is positioned within annular space  118  and contacts the adhesive applied to reduced diameter portion  112 .  
         [0046]    Referring to FIGS. 7 and 8, a cup member  120  and a lid member  130  of a piston  10  manufactured by a method according to a second embodiment of the present invention is depicted. The features and advantages of the second embodiment of the present invention are similar to the features and advantages of the first embodiment of the present invention. Therefore, those similar features and advantages of the first embodiment and the second embodiment of the present invention are not discussed further with respect to the second embodiment of the present invention. Referring to FIG. 7, in the second embodiment, cup member  120  may comprise a first ring portion  121 , a second ring portion  122 , a third ring portion  123 , and a cylindrical portion  124 . Second ring portion  122  and third ring portion  123  form a peripheral surface of piston head  10   b . Second ring portion  122  may have a thickness which is about equal to a thickness of cylindrical portion  124 , and a thickness of third ring portion  123  may be greater than the thickness of second rings portion  122  and cylindrical portion  123 . Second ring portion  122  may have an outer diameter which is about equal to an outer diameter of third ring portion  123  and cylindrical portion  124 . Moreover, an inner diameter of second ring portion  122  may be about equal to an inner diameter of cylindrical portion  124 , and also may be greater than an inner diameter of third ring portion  123 . Third ring portion  123  may have a receiving surface  123   a , e.g., a ring-shaped receiving surface.  
         [0047]    First ring portion  121  forms a brim of cup member  120 . An outer diameter of first ring portion  121  may be greater than the outer diameter of second ring portion  122  measured from the center of piston head  10   b , and an inner diameter of first ring portion  121  may be greater than or equal to the inner diameter of second ring portion  122  measured from the center of piston head  10   b . Moreover, first ring portion  121 , second ring portion  122 , third ring portion  123  may form an annular recess  125 , and receiving surface  123   a  forms the bottom of annular recess  125 .  
         [0048]    Referring to FIG. 8, lid member  130  may comprise an end portion  131 , e.g., a ring-shaped end portion or a disc-shaped end portion, and a reduced diameter portion  132 . A recess  34  may be formed in end portion  131  and reduced diameter portion  132  to reduce the weight of lid member  130 . A periphery  131   a  of end portion  131  may have an outer diameter which is less than or about equal to the inner diameter of second ring portion  122 . End portion  131  also may have a contact surface  131   b , e.g., a ring-shaped contact surface which contacts receiving surface  123   a  when lid member is positioned inside cup member  120 . Moreover, reduced diameter portion  132  may have a surface  132   a  which forms an end surface of piston head  10   b , and a periphery  133  having has an outer diameter which decreases between end portion  131  and surface  132   a.    
         [0049]    Referring to FIG. 9, in this embodiment, cup member  120  may be inserted in opening  63  from second end  62 , such that at least a portion of cylindrical portion  124  is aligned with first inner portion  64 , first ring portion  121 , second ring portion  122 , and third ring portion  123  are aligned with second inner portion  65 , and shoe supporter  10   a  extends beyond first end  61 . First semi-circular portion  60   a  or second semi-circular portion  60   b , or both, subsequently may be fitted to surround cylindrical portion  124 , and semi-circular portion  60   a  and second semi-circular portion  60   b  then may be fixed to each other. In another embodiment, if shoe supporter  10   a  does not extend beyond cylindrical portion  124  in a radial direction, opening  63  may be formed, such that swaging tool  60  may be single body having opening  63  formed therethrough, i.e., swaging tool  60  is not divided into first semi-circular portion  60   a  and second semi-circular portion  60   b . In this embodiment, cup member  100  simply may be inserted in opening  63  from second end  62 , such that at least a portion of cylindrical portion  124  is surrounded by first inner portion  64 .  
         [0050]    In any of the above-described embodiments, an adhesive may be applied to curved periphery  133  of reduced diameter portion  132 , and end portion  131  and reduced diameter portion  132  subsequently may be inserted into cup member  110 , such that surface  131   b  of lid member  130  contacts receiving surface  123   a  of third ring portion  123 , periphery  131   a  contacts an inner surface of second ring portion  122 , and reduced diameter portion  132  is aligned with first ring portion  121 . Moreover, an annular groove  138  may be formed by an inner surface of first inner portion  121  and curved periphery  133 .  
         [0051]    Referring to FIG. 10, pushing tool  70  may be used to push cup member  120  and lid member  130  toward first end  61  of swaging tool  60 . When lid member  130  and cup member  120  are pushed within first inner portion  64 , disc portion  72  of pushing tool  70  closes annular groove  138 . Moreover, first inner portion  64  swags first ring portion  121  in a direction toward annular groove  138 , such that at least a portion of first ring portion  121  is positioned within annular grove  138  and contacts the adhesive applied to curved periphery  133 . Consequently, cup member  120  may be fixed to lid member  130  without form a gap between cup member  120  and lid member  130 . Lid member  130  and cup member  120  also may be modified in accordance with the embodiment of the present invention depicted in FIG. 6.  
         [0052]    Referring to FIGS. 11 and 12, a cup member  150  and a lid member  140  of a piston  10  manufactured by a method according to a third embodiment of the present invention is depicted. The features and advantages of the third embodiment of the present invention are similar to the features and advantages of the above-described embodiments of the present invention. Therefore, those similar features and advantages of the above-described embodiments and the third embodiment of the present invention are not discussed further with respect to the third embodiment of the present invention. Referring to FIG. 11, in the third embodiment, lid member  140  may comprise a first ring portion  141 , a second inner portion  142 , and a disc portion  143 . Lid member  140  may have a recess  144  formed therein, which may be shallower than the recess formed in lid member  110  or  130 , or both. First ring portion  141  forms a brim of lid member  140 , and disc portion  143   a  has a surface  143   a  which forms an end surface of piston head  10   b . Disc portion also may have a periphery  143   b  which may be tapered toward end surface  143   a , or may have a cylindrical shape. An outer diameter of second ring portion  142  may be about equal to an outer diameter of piston head  10   b , and an outer diameter of first ring portion may be greater than the outer diameter of second ring portion  102 . In an embodiment, an inner diameter of first ring portion  141  may be equal to an inner diameter of second ring portion  142 . In another embodiment, the inner diameter of first ring portion  141  may be greater than the inner diameter of second inner portion  142 . Moreover, first ring portion  141  may have a receiving surface  141   a which is one end surface of lid member  140 .  
         [0053]    Referring to FIG. 12, cup member  150  may comprise an end portion  151 , e.g., a ring-shaped, end portion, a reduced diameter portion  152 , a connection portion  153 , and a cylindrical portion  154 . Connection  153  and cylindrical portion  154  may form a peripheral surface of piston head  10   b . Connection portion  173  and cylindrical portion  154  each may have an outer diameter which is about equal to the outer diameter of second ring portion  142 . Moreover, connection portion  153  may have a constant inner diameter, or may have an inner diameter which increases between a reduced diameter portion  152  and cylindrical portion  154 . Connection portion  153  also may have a contact surface  153   a  which contacts receiving surface  141   a  of first ring portion  141 . A periphery  151   a  of end portion  151  may have an outer diameter which may be smaller than or about equal to the inner diameter of second ring portion  142 . Moreover, end portion  151 , reduced diameter portion  152 . and connection portion  153  may form an annular groove  155 .  
         [0054]    Referring to FIG. 13, in this embodiment, an adhesive may be applied to the periphery of reduced diameter portion  152 , and end portion  151  and reduced diameter portion  152  subsequently may be inserted into recess  144 , such that contact surface  153   a  of connection portion contacts receiving surface  141   a  of lid member  140 , periphery  151   a  contacts an inner surface of second inner portion  142 , and reduced diameter portion  152  is aligned with first ring portion  141 . Moreover, an annular space  158 , which is a portion of annular groove  155 , may be formed by first ring portion  141  and reduced diameter portion  152 .  
         [0055]    Referring to FIG. 14, pushing tool  70  may be used to push cup member  150  and lid member  140  toward first end  61  of swaging tool  60 . When lid member  140  and cup member  150  are pushed within first inner portion  64 , first inner portion  64  swags first ring portion  141  in a direction toward annular space  158 , such that at least a portion of first ring portion  141  is positioned within annular space  158  and contacts the adhesive applied to the periphery of reduced diameter portion  152 . Consequently, cup member  150  may be fixed to lid member  140  without forming a gap between cup member  150  and lid member  140 . Lid member  140  and cup member  150  also may be modified in accordance with the embodiment of the present invention  
         [0056]    Referring to FIGS. 15 and 16, a cup member  170  and a lid member  160  of a piston  10  manufactured by a method according to a fourth embodiment of the present invention is depicted. The features and advantages of the fourth embodiment of the present invention are similar to the features and advantages of the above-described embodiments of the present invention. Therefore, those similar features and advantages of the above-described embodiments and the fourth embodiment of the present invention are not discussed further, with respect to the fourth embodiment of the present invention. Referring to FIG. 15, in the fourth embodiment, lid member  160  may comprise a first ring portion  161  and a second ring portion  162 , which are substantially similar to first ring portion  141  and second ring portion  142 , respectively. Lid member  160  may have a recess  163  formed therein, which may be shallower than the recess formed in lid member  110  or  130 , or both. Moreover, first ring portion  161  may have a receiving surface  161   a  which is one end surface of lid member  160 .  
         [0057]    Referring to FIG. 16, cup member  170  may comprise an end portion  171 , a reduced diameter portion  172 , a connection portion  173 , and a cylindrical portion  174 , which are substantially similar to end portion  151 , reduced diameter portion  152 , connection portion  153 , a cylindrical portion  154 , respectively. Connection portion  173  may have a contact surface  153   a  which contacts receiving surface  161   a  of first ring portion  161 , and end portion  171  may have a periphery  171   a  similar to periphery  151   a . Moreover, end portion  171 , reduced diameter portion  172 , and connection portion  173  may form an annular groove  175 . In this embodiment, a bottom of cup member  170  may comprise a tapered end disc portion  176  which is an end surface of piston head  10   b.    
         [0058]    Referring to FIG. 17, in this embodiment, end portion  171  and reduced diameter portion  172  may be inserted into recess  163 , in a manner similar to the third embodiment, such that an annular space  178 , which is a portion of annular groove may be formed by first ring portion  171  and reduced diameter portion  172 .  
         [0059]    Referring to FIG. 18, in this embodiment, neck portion  10   c  and shoe supporter  10   a  may be used to push cup member  170  and lid member  160  toward first end  61  of swaging tool  60 . When lid member  160  and cup member  170  are pushed within first inner portion  64 , first inner portion  64  swags first ring portion  161  in a direction toward annular space  178 , such that at least a portion of first ring portion  161  is positioned with annular space  178 . Consequently, cup member  170  may be fixed to lid member  160  without forming a gap between cup member  170  and lid member  160 . Lid member  160 , and cup member  170 , also may be modified in accordance with the embodiment of the present invention depicted in FIG. 6.  
         [0060]    While the invention has been described in connection with preferred embodiments, it will be understood by those skilled in the art that other variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples are consider exemplary only, with the true scope of the invention indicated by the following claims.