Patent Publication Number: US-6339948-B1

Title: Process of forming annular member from cylindrical member having radial flange at one end

Description:
This application is based on Japanese Patent Application No. 11-246997 filed Sep. 1, 1999, the contents of which are incorporated hereinto by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a process of forming an annular member such as a ring used for a manufacturing desired products such as automotive vehicle parts, or used as blanks that are to be cold-forged to manufacture desired products. 
     2. Discussion of Related Art 
     There are available various processes of forming an annular member as described below. One of the known processes includes a blanking operation and a piercing operation. In this process, a strip  10  supplied from a coil of strip is subjected to a blanking operation to punch out a plurality of workpieces in the form of circular plates  12  while the strip  10  is fed, as shown in FIG.  1 A. Each circular plate  12  has the same outside diameter and outer profile as a desired ring member  14  to be manufactured. In the left half of FIG. 1B (on the left side of a one-dot chain line indicated in the figure), the circular plate  12  is shown in cross section. Then, the circular plate  12  is subjected to a piercing operation to remove a radially inner portion thereof, for thereby obtaining the ring member  14 , as shown in cross section in the right half of FIG.  1 B. The diameter of the radially inner portion to be removed by piercing is equal to the inside diameter of the ring member  14 . However, the process including the blanking and piercing operations described above suffers from a considerably low yield ratio. 
     Another known process of forming a ring member includes a blanking operation, a compressing operation and a piercing operation. In this process, the strip  10  is initially subjected to a blanking operation to punch out a plurality of workpieces also in the form of circular plates  18  each of which has an outside diameter smaller than that of a desired ring member  16  to be manufactured, as shown in FIGS. 2A and 2B. In the left half of FIG. 2B (on the left side of a one-dot chain line indicated in the figure), the circular plate  18  is shown in cross section. Then, the circular plate  18  is subjected to a compressing operation to compress a radially inner portion thereof, as sown in the right half of FIG. 2B, for thereby reducing the thickness of the radially inner portion and enlarging the diameter of the circular plate  18  to the outside diameter of the ring member  16 . Finally, the compressed circular plate  18  is subjected to a piercing operation to remove a radially inner portion thereof, for thereby obtaining the ring member  16 , as shown in cross section in the right half of FIG.  2 C. The diameter of the inner portion to be removed by piercing is equal to the inside diameter of the ring member  16 . This process assures a comparatively high degree of hardness of the ring member  16  owing to the compressing operation on the circular plate  18 , leading to improved strength of the product to be manufactured from the ring member  16 . Further, this process assures a higher yield ratio than the process of FIGS. 1A and 1B. However, the yield ratio in the process of FIGS.  2 A-Ac is still unsatisfactory. Further, the present process is not applicable to a strip (blank sheet) having a comparatively small thickness. 
     A further alternative known process for forming a ring member includes a roll bending operation on a strip. Described more specifically referring to FIGS. 3A-3C, a plurality of narrow strips  20  shown in cross section in FIG. 3A each having a relatively small width are formed from the strip  10 . Each narrow strip  20  is formed into an annular member by roll bending. The thus obtained annular member has a seam  22 , as indicated in FIG.  3 B. Finally, the annular member is subjected to a calking operation or a welding operation at the seam  22 , to thereby form a ring member  24  as shown in FIG.  3 C. This process assures a significantly improved yield ratio. In the presence of the seam  22  on the ring member  24 , however, the present process suffers from a low strength of the product to be manufactured from the ring member  24 . Further, the process is not applicable to a strip having a comparatively large thickness. 
     JP-A-2-27058 discloses a further alternative process of forming a ring member, which includes a forging operation on one longitudinal end portion of a blank in the form of a round bar, and a shearing operation on the formed longitudinal end portion. Described in detail, the longitudinal end portion of the round bar is subjected to a forging operation with a die set including a female die and a male die, such that a punch portion of the male die is moved into a die hole of the female die, to cause deformation of the longitudinal end portion of the rod held in the die hole, so that a circular recess is formed in the end face of the end portion of the rod. Thus, the circular recess is defined by the annular wall whose outside diameter is larger than the original diameter of the rod. The thus forged longitudinal end portion of the rod is subjected to a shearing operation to cut off only the annular wall portion from the forged end portion of the rod, whereby a ring member constituted by the annular wall is obtained. Where the diameter or transverse cross sectional area of the round rod is comparatively large, a large forging force is required to be applied to the longitudinal end portion, for forming the above-indicated recess defined by the annular wall. Therefore, the present process is not available when the ring member to be manufactured has a comparatively large outside diameter. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a process which permits an annular member to be formed with a sufficiently high yield ratio, with reduced limitations in the diameter and thickness of the ring member. 
     The above object may be achieved according to the principle of the present invention, which provides a process of forming at least one annular member from a cylindrical member, comprising the steps of: (a) applying a force to said cylindrical member in an axial direction thereof, to thereby cause plastic deformation at one of opposite axial end portions of the cylindrical member, such that a flange extends in a generally radial direction from one of opposite axial ends of the cylindrical member which corresponds to the above-indicated one of the opposite axial end portions; and (b) effecting a shearing operation on the flange to punch out the annular member. 
     In the process of the present invention, an axial force is applied to the cylindrical member in its axial direction, in the plastic deformation step, so as to cause plastic deformation at one axial end portion thereof, such that a flange extends from the corresponding one axial end of the cylindrical member in a generally radial direction of the cylindrical member. In the next shearing step, the flange is subjected to a shearing operation to punch out the desired annular member. Therefore, the present process permits the annular member to be formed with reduced limitations in the size and thickness of the annular member. 
     In a first preferred form of the present invention, a plurality of annular members are successively formed from the cylindrical member, such that the step of applying a force to the cylindrical member and the step of effecting a shearing operation are repeatedly implemented after a first one of the plurality of annular members is punched out. In this instance, the cylindrical member whose flange has been subjected to the shearing operation to punch out each annular member is subjected to the plastic deformation so as to again form the radially extending flange, and this flange is again subjected to a shearing operation to punch out the next one of the plurality of annular members. The process according to the present preferred form of the invention assures a relatively high yield ratio of the annular members. 
     In a second preferred form of this invention, the process further comprises a step of preparing the cylindrical member which includes a cylindrical wall and an inward flange as the above-indicated flange at one of opposite axial ends of the cylindrical wall, the inward flange being formed by plastic deformation when the cylindrical member is formed such that the inward flange extends radially inwardly of the cylindrical wall, and wherein the inward flange as formed by plastic deformation is further subjected to plastic deformation in the above-indicated step of applying a force to the cylindrical member and the above-indicated step of effecting a shearing operation. In this arrangement, the inward flange is first subjected to the plastic deformation when the cylindrical member with this inward flange is formed, and is again subjected to the plastic deformation with an axial force applied to the cylindrical member such that the material of the corresponding axial end portion of the cylindrical member flows in the radially inward direction of the cylindrical wall. Accordingly, the ring member punched out from the inward flange has an increased strength. 
     In one advantageous arrangement of the second preferred form of the invention, the cylindrical member with the inward flange is formed by the steps of: subjecting a strip to a blanking operation to punch out a circular plate; subjecting the circular plate to a drawing operation to produce a cylindrical-container consisting of a cylindrical wall and a bottom wall at one of opposite axial ends of the cylindrical wall: and subjecting the bottom wall to a blanking operation to form an opening through the bottom wall, for thereby forming the inward flange, such that the opening has a profile similar to an inner profile of the annular member. This arrangement permits the ring members to be formed from the blank in the form of a strip with a high yield ratio. 
     In a third preferred form of this invention, the process further comprises a step of preparing the cylindrical member which includes a cylindrical wall and an outward flange as the above-indicated flange at one of opposite axial ends of the cylindrical wall, the inward flange being formed by plastic deformation when the cylindrical member is formed such that the outward flange extends radially outwardly of the cylindrical wall, and wherein the outward flange as formed by plastic deformation is further subjected to plastic deformation in the above-indicated step of applying a force to the cylindrical member and the above-indicated step of effecting a shearing operation. This preferred form of the invention has substantially the same advantage as the second preferred form of the invention described above. 
     The annular member may be a ring member having circular inner and outer profile, or any other member having elliptical or other inner and outer profiles. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     The above and other objects, features, advantages and technical and industrial significance of the present invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings, in which: 
     FIGS. 1A and 1B are views illustrating a known process of forming a ring member, which process includes blanking and piercing operations; 
     FIGS. 2A,  2 B and  2 C are views illustrating another known process of forming a ring member, which process includes blanking, compressing and piercing operations; 
     FIGS. 3A,  3 B and  3 C are views illustrating a further known process of forming a ring member, which process includes a roll bending operation on a narrow strip; 
     FIG. 4 is a cross sectional view illustrating a ring member formed according to a first embodiment of this invention; 
     FIG. 5 is a flow chart illustrating steps of forming a cylindrical member from which a plurality of ring members are formed; 
     FIGS. 6A,  6 B and  6 C are views showing a cylindrical container and the cylindrical member to be obtained from the cylindrical container, which cylindrical container and member are formed according to the process illustrated in the flow chart of FIG. 5; 
     FIG. 7 is a flow chart of steps for successively forming ring members. 
     FIG. 8 is an elevational view in cross section schematically showing a press used as an axially pressing apparatus in plastic deformation step SB 1  of the flow chart of FIG. 7; 
     FIG. 9 is an elevational view in cross section schematically showing a blanking or shearing press used in blanking or shearing step SB 2  of the flow chart of FIG. 7; 
     FIG. 10 is a press used as an alternative axially pressing apparatus in the plastic deformation step SB 1 , in a second embodiment of the present invention; 
     FIG. 11 is an elevational view in cross section schematically showing a press which is used in a further embodiment of the invention and which functions as an axially pressing apparatus and a blanking or shearing apparatus; 
     FIG. 12 is an elevational view in cross section showing the shearing step SB 2  in a third embodiment of this invention; and 
     FIG. 13 is an elevational view in cross section schematically showing a press used as the axially pressing apparatus in a fourth embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIGS. 4-9, there will be described the first embodiment of the present invention, wherein annular members in the form of ring members  30  shown in FIG. 4 are successively formed. Each ring member  30  has circular inner and outer profiles, and an inside diameter of 50 mm, an outside diameter of 60 mm and a thickness of 5 mm. 
     The ring member  30  is formed from a cylindrical member  32 , which in turn is formed from a cylindrical container  36 , as illustrated in FIGS. 5 and 6. A process of forming the cylindrical container  36  is illustrated in the flow chart of FIG.  5 . To form the cylindrical member  32 , a strip  10  is subjected to a blanking operation in step SA 1  of the flow chart of FIG. 5, to punch out a plurality of workpieces in the form of circular plates  34 , as shown in FIG.  6 A. It will be understood that the step SA 1  is a step of subjecting a strip to a blanking operation to punch out a circular plate. The diameter of the circular plates  34  punched out from the strip  10  is determined based on experimental data, so that a predetermined number of the ring members  30  can be formed from each circular plate  34 . In the present embodiment, the diameter of the circular plates  34  is determined to obtain ten ring members  30  from each circular plate  34 . 
     Step SA 1  is followed by step SA 2  in which the circular plate  34  is subjected to a drawing operation, to produce the cylindrical container  36 , which is closed at one of its opposite axial ends and is open at the other axial end. It will be understood that the step SA 2  is a step of subjecting the circular plate  34  to produce the cylindrical container  36 . The cylindrical container  36  consists of a cylindrical wall  40  and a bottom wall  38  which closes one of the opposite axial ends of the cylindrical wall  40 , as shown in cross section in the right half of FIG.  6 B. In the left half of FIG. 6B, the circular plate  34  is shown in cross section. The inside diameter of the cylindrical container  36  is made larger by a predetermined amount than the outside diameter of the ring member  30  to be eventually formed. In the present embodiment, the inside diameter of the cylindrical container  36  is 70 mm, while the outside diameter of the ring member  30  is 60 mm, as indicated in FIG.  4 . 
     Then, step SA 3  is implemented to effect a piercing operation on the bottom wall  38 , for punching out a circular plate  41 , as shown in FIG.  6 C. The circular plate  41  has the outside diameter equal to the outside diameter of the ring member, namely, 60 mm. As a result, the bottom wall  38  is replaced by an inward flange  39  having a circular bottom opening  43  that has a diameter of 60 mm, as indicated in cross section in the right half of FIG.  6 C. Thus, the cylindrical member  32  from which the ring members  30  are to be formed is prepared. It will be understood that the step SA 3  is a step of subjecting the inward flange  39  of the cylindrical container  36  to a blanking operation to form therethrough the opening  43  whose profile is similar to the inner profile of the ring member  30 , so that the cylindrical member  32  is produced. 
     Referring next to the flow chart of FIG. 7, there will be described steps of successively forming the ring members  30  from the cylindrical member  32  which is produced as described above. Initially, step SB 1  is implemented on an axially pressing apparatus in the form of a press  42 , to apply an axial force to the cylindrical member  32  so as to effect plastic deformation of one axial end portion of the cylindrical member  32  on the side of the opening  43  such that the material flows from the axial end portion in question in the radially inward direction, so that the diameter of the opening  43  is reduced. 
     The construction of the press  42  is schematically shown in FIG.  8 . The left half of FIG. 8 (to the left of the one-dot chain line in the figure) shows the state of the press  42  before its operation, while the right half of FIG. 8 shows the state of the press  42  after the cylindrical member  32  has been subjected to plastic deformation on the press  42 . 
     The press  42  includes a horizontally extending lower plate  44  and a lower die  46  which has a die hole  48  in which the cylindrical member  32  is fitted. The press  42  further includes an upper plate  50  which is parallel to the lower plate  44  and which is bolted or otherwise fixed to a ram not shown. The upper plate  50  is moved with the ram when the ram is hydraulically moved. To the upper plate  50 , there is attached a cylindrical punch  52  through a punch retainer  54 . The annular end face of the cylindrical punch  52  on the side of the lower die  46  has a circular shape identical with the shape of the cylindrical member  32  in transverse cross section. That is, the cylindrical punch  52  has the same inside and outside diameters as the cylindrical member  32 . The cylindrical punch  52  is attached to the upper plate  50  such that the axis of the punch  52  is perpendicular to the upper plate  50 . The axial length and the operating stroke of the ram (i.e., of the upper plate  50 ) are determined so that the lower end of the punch  52  can be brought into abutting contact with an upper end face  67  of the cylindrical member  32  positioned within the die hole  48 . 
     The upper plate  50  has a stepped hole  55  consisting of a large-diameter portion  56  and a small-diameter portion  62  which cooperate to define an annular shoulder surface  57  therebetween. The press  42  further includes a cylindrical internal pressure member  58  which is supported by the upper plate  50 . Namely, the pressure member  58  includes a lower large-diameter portion having a diameter substantially equal to the inside diameter of the cylindrical member  32 , and an upper small-diameter portion whose upper end section extends through the small-diameter portion  62  of the stepped hole  55 . The small-diameter portion of the pressure member  58  has a diameter substantially equal to the diameter of the small-diameter portion  62 , so that the pressure member  58  is axially slidably movable relative to the upper plate  50 . The pressure member  58  is provided with a stop  60  in the form of a circular disk fixed to the end face of its small-diameter portion. The stop  60 , which has the same diameter of the large-diameter portion  56  of the stepped hole  55 , is fitted in this large-diameter portion  56 . The large-diameter portion of the pressure member  58  has a horizontal lower end face  63  for contact with the bottom wall of the cylindrical member  32 . 
     A coil spring  64  is disposed in an annular space between the inner circumferential surface of the cylindrical punch  52  and the outer circumferential surface of the small-diameter portion of the internal pressure member  58 , such that the upper end of the coil spring  64  is held in contact with the lower surface of the upper plate  50 , while the lower end of the coil spring  64  is held in contact with the shoulder surface between the large- and small-diameter portions of the pressure member  58 . The coil spring  64  biases the pressure member  58  in the downward direction, that is, toward the bottom of the die hole  48 . Thus, the pressure member  58  is normally held in place with the stop  60  held in contact with the annular shoulder surface  57  under the biasing force of the coil spring  64 . When the cylindrical punch  52  is moved down with the upper plate  50  relative to the lower die  46 , the lower section of the large-diameter portion of the pressure member  58  is moved into the cylindrical member  32  fitted in the die hole  48 , so that the cylindrical member  32  is forced onto the bottom surface of the die hole  48 . After the lower end face of the pressure member  58  has been brought into contact with the inward flange  39 , the stop  60  is moved away from the shoulder surface  57  with the coil spring  64  being compressed, as indicated in the right half of FIG.  8 . It will be understood that the internal pressure member  58  and the coil spring  64  cooperate to function as a presser device  66  for holding the cylindrical member  32  in the die hole  48  while forcing the cylindrical member  32  onto the bottom surface of the die hole  48 . 
     In the step SB 1  of FIG. 7 indicated above, the upper plate  50  is lowered to move the cylindrical punch  52  into the die hole  48 , for abutting contact with the upper end face  67  of the cylindrical member  32 , to thereby axially force the cylindrical member  32  so that the upper end face  67  is lowered by a predetermined suitable distance in the axial direction. As indicated above, the diameter (60 mm) of the circular bottom opening  43  of the cylindrical member  32  before the plastic deformation in the step SB 1  is equal to the outside diameter of the ring member  30  to be formed. The above-indicated axial distance by which the upper end face  67  is lowered by the downward movement of the punch  52  on the press  42  is determined based on experimental data so that the original diameter (60 mm) of the circular bottom opening  43  (inside diameter of the inward flange  39 ) is reduced to the inside diameter (50 mm) of the ring member  30 . As a result, the reduction of the inside diameter of the inward flange  39  by the plastic deformation of the lower end portion of the cylindrical member  32 , the hardness of the member  32  is increased at its lower end portion whose inward flange  39  has the inside diameter equal to the inside diameter of the ring member  30 . 
     The plastic deformation step SB 1  is followed by step SB 2  in which the inward flange  39  is subjected to a shearing or blanking operation on a shearing or blanking press  70 , to punch out the ring member  30 , as shown in the cross sectional view of FIG. 9 showing the shearing press  70 . In the left half of FIG. 9 (to the left of the one-dot chain line in the figure), there is shown the cylindrical member  32  before the shearing operation to punch out the ring member  30 . In the right half of FIG. 9, there is shown the cylindrical member  32  after the shearing operation, namely, after the ring member  30  is punched out by shearing off the radially inner portion of the inward flange  39 . 
     The shearing or blanking press  70  includes a horizontally extending lower plate  72 , and a lower die  74  fixedly mounted on the lower plate  72 . The lower die  74  has a die hole  76  in which the cylindrical member  32  which has been subjected to the plastic deformation on the press  42  is fitted. The die hole  76  includes a lower end portion serving as a shearing hole  78 . The diameter of the shearing hole  78  at its upper open end is equal to the outside diameter of the ring member  30  to be obtained. 
     The shearing press  70  further includes an upper plate  80  which is parallel to the lower plate  72  and which is bolted or otherwise fixed to a ram not shown. To the upper plate  80 , there is attached a cylindrical punch  82  through a punch retainer  84  such that the cylindrical punch  82  is concentric with the shearing hole  78 . The punch  82  has a diameter equal to the outside diameter of the ring member  30 , and an axis perpendicular to the lower plate  72  (upper plate  80 ). The punch  82  has a lower end face parallel to the lower plate  72 . 
     In the shearing step SB 2  implemented after the plastic deformation step SB 1  in which the inside diameter of the inward flange  39  of the cylindrical member  32  is reduced to the inside diameter (50 mm) of the ring member  30 , the upper plate  80  is moved down to lower the cylindrical punch  82  into the cylindrical member  32  fitted in the die hole  76 , so that the inward flange  39  having the opening  43  is subjected to a shearing operation by and between the punch  82  and the lower die  74 , for thereby punching out the ring member  30  from the inward flange  39 . 
     Then, step SB 3  is implemented to determine whether a predetermined number of the ring members  30  have been produced or formed from the cylindrical member  32 . In the present embodiment, step SB 3  is implemented to determine whether a total of ten ring members  30  have been formed from the cylindrical member  32 . If a negative decision (NO) is obtained in step SB 3 , the control flow goes back to step SB 1  to effect the plastic deformation of the cylindrical member  32  on the press  42 , so as to reduce the diameter of the bottom opening  43  again to the inside diameter of the ring member  30 . Then, step SB 3  is implemented to effect the shearing operation again on the inward flange  39  of the cylindrical member  32  on the shearing press  70 , so that another ring member  30  is produced. Steps SB 1  and SB 2  are repeatedly implemented until an affirmative decision (YES) is obtained in step SB 3 , that is, until a total of ten ring members  30  have been obtained from the same cylindrical member  32 . The present process assures the successive formation of the plurality of ring members  30  with a significantly increased yield ratio. 
     In the process of forming the ring member  30  according to the present embodiment of the invention, the cylindrical member  32  is axially pressed in the plastic deformation step SB 1 , to plastically deform the lower end portion of the cylindrical member  32 , so as to reduce the diameter of the bottom opening  43  to the inside diameter of the ring members  30  to be formed. In the next shearing or blanking step SB 2 , the plastically deformed inward flange  39  of the cylindrical member  32  is subjected to a shearing or blanking operation to punch out one ring member  30  at one time, with reduced limitations in the size and thickness of the ring member  30 . 
     Further, the present embodiment is adapted such that the cylindrical member  32  is repeatedly subjected to the plastic deformation step SB 1  and the shearing step SB 2  to punch out a total of ten ring members  30  one after another with a high yield ratio. 
     It is also noted that the lower end portion of the cylindrical member  32  is repeatedly subjected to the axial and radially inward plastic deformation, such that the extreme end portion of the cylindrical wall  40  of the cylindrical member  32  eventually provides the inward flange  39 , and so that the inward flange  39  is sufficiently hardened owing to the repeated implementation of the plastic deformation step SB 1 . Accordingly, the ring members  30  formed from the inward flange  39  have a high degree of strength. In particular, the strength of the ring members  30  which are formed after a relatively large number of implementation of the plastic deformation step SB 1  is considerably high. 
     In the present process, the cylindrical member  32  is formed by initially performing a blanking operation on the strip  10  to punch out a plurality of circular plates  34  in the blanking step SA 1 , then performing a drawing operation on each circular plate  34  so as to form the cylindrical container  36  in the drawing step SA 2 , and finally performing a piercing operation on the bottom wall  38  of the cylindrical container  36  so as to form the bottom opening  43  through the inward flange  39  in the piercing step SA 3 . 
     Referring next to the cross sectional views of FIGS.  10 - 13 , there will be described other embodiments of the present invention, in which the same reference signs as used in the first embodiment of FIGS. 4-9 are used to identify the functionally corresponding elements. 
     In the embodiment of FIG. 10, an axially pressing apparatus in the form of a press  90  is used in place of the press  42  of FIG.  8 . The press  90  employs a cylindrical stop  94  incorporated in the lower portion of the lower die  46  such that the stop  94  partially projects into the die hole  48 , from a bottom surface  92  of the die hole  48 . The amount of upward projection of the cylindrical stop  94  from the bottom surface  92  is equal to the thickness of the inward flange  39 . The cylindrical stop  94  has a diameter equal to the inside diameter of 50 mm of the ring member  30 . 
     In the plastic deformation step SB 1 , the cylindrical member  32  fitted in the die hole  48  of the lower die  46  of the press  90  is subjected to the plastic deformation so that the inner circumferential surface of the bottom opening  43  is brought into abutting contact with an outer circumferential surface  96  of the cylindrical stop  94 . Thus, the cylindrical stop  94  functions as a member for reducing the diameter of the bottom opening  43  exactly to the inside diameter (50mm) of the ring member  30  to be formed. In this second embodiment, too, the thus plastically deformed cylindrical member  32  is subjected to a shearing operation on the press  70  of FIG. 9, to punch out the ring member from the bottom wall  38 , in the shearing or blanking step SB 2 . 
     As described above, the second embodiment which employs the press  90  including the cylindrical stop  94  permits accurate plastic deformation of the cylindrical member  32  so as to form the bottom wall  38  such that the bottom opening  43  has the diameter which is exactly the same as the inside diameter of the ring member  30  to be formed. Accordingly, the present embodiment permits improved dimensional accuracy of the ring members  30 . 
     In the third embodiment of FIGS. 11 and 12, a press  100  is used in place of the presses  42  and  70  of FIGS. 8 and 9 used in the first embodiment. Namely, the press  100  serves as not only the axially pressing apparatus but also the shearing press. The left half of FIG. 11 shows the cylindrical member  32  before the plastic deformation, while the right half of FIG. 11 shows the cylindrical member  32  after the plastic deformation. The left half of FIG. 12 shows the cylindrical member  32  before the shearing or blanking operation on the inward flange  39 , while the right half of FIG. 12 shows the cylindrical member  32  after the shearing operation on the inward flange  39 . 
     The press  100  includes a horizontally extending lower plate  102 , and a lower die  104  fixedly mounted thereon. The lower die  104  has the same configuration as the lower die  74  of the press  70  of FIG. 9, and has a die hole  106  in which the cylindrical member  32  is fitted. The die hole  106  includes a lower end portion serving as a shearing hole  108  whose diameter is equal to the outside diameter (60mm) of the ring member  30  to be formed. The press  10  further includes a cylindrical outer punch  110  having the same inside and outside diameters as the cylindrical member  32 . The outer punch  110  is fixed to a first ram not shown, such that the outer punch  110  is concentric with the cylindrical member  32  fitted in the die hole  106 . The press  10  further includes a cylindrical inner punch  112  having an outside diameter equal to the outside diameter of the ring member  30 . The inner punch  112  is fixed to a second ram not shown, such that the inner punch  112  is concentric with the shearing hole  108 . Between the outer and inner punches  110 ,  112 , there is disposed a cylindrical intermediate punch  114  fixed to a third ram not shown. The intermediate punch  114  is axially slidable in contact with the outer and inner punches  110 ,  112 . The first, second and third rams are connected to respective hydraulically operated cylinders, so that the three punches  110 ,  112 ,  114  connected to the respective rams are axially movable toward and away from the lower plate  102 . That is, the press  100  is a hydraulically operated double-action press. The mutually independent connections of the outer, inner and intermediate punches  110 ,  112 ,  114  with the respective hydraulically operated cylinders are indicated by symbols in the upper end of FIGS. 11 and 12. 
     The left half of FIG. 11 shows the operating state of the press  100  in which the lower end face of the outer punch  110  is in abutting contact with the upper end face of the cylindrical member  32  fitted in the die hole  106  of the lower die  104 , while the lower end face of the intermediate punch  114  is in contact with the inner surface of the inward flange  39  of the cylindrical member  32 . In this state, the outer punch  110  is lowered a predetermined distance to effect the plastic deformation of the lower end portion of the cylindrical member  32  so that the diameter of the bottom opening  43  is reduced to the inside diameter (50 mm) of the ring member  30  to be formed. This is the plastic deformation step SB 1 . The right half of FIG. 11 shows the cylindrical member  32  after the plastic deformation step SB 1  is implemented. 
     The left half of FIG. 12 shows the same state of the press  100  as shown in the right half of FIG.  11 . The right half of FIG. 12 shows the ring member  30  which has been punched out from the inward flange  39  in the shearing or blanking step SB 2 . In this shearing step SB 2 , the inner punch  112  is lowered to effect the shearing operation on the inward flange  39  so as to punch out the ring member  30  whose outside diameter is equal to the diameter of the inner punch  112 . 
     Then, the inner punch  112  is moved upwards away from the inward flange  39  of the cylindrical member  32 , and the outer punch  110  is again lowered to effect the plastic deformation of the cylindrical member  32  so as to reduce the diameter of the bottom opening  43  to the inside diameter of the ring member  30  to be formed. Then, the inner punch  112  is again lowered to punch out the ring member  30  from the bottom wall  38 . By repeating the above steps, the plurality of ring members  30  can be formed one after another from the same cylindrical members  32 . 
     In the fourth embodiment of FIG. 13, a press  120  is used as the axially pressing apparatus, in place of the press  42  of FIG.  8 . The press  120  is adapted to implement the plastic deformation step SB 1  on a cylindrical member  122 , which is different from the cylindrical member  32  in that the cylindrical member  122  has an outward flange portion  154  at the lower end, rather than the inward flange  39 . The press  120  is adapted to effect the plastic deformation of the lower end portion of the cylindrical member  122  which includes the outward flange  154 . The cylindrical member  122  may be formed, for example, by cutting a tubular member into a plurality of tubes, and subjecting one axial end portion of each tube to a spinning operation, for plastically deforming the end portion of the tube so as to form the outward flange  154 . 
     The press  120  includes a horizontally extending lower plate  126 , and a lower die  128  fixedly mounted on the lower plate  126 . The lower die  128  has a die hole  130 , and includes a central cylindrical projection  132  which extends upward from a horizontal bottom surface  131  of the die hole  130 . The cylindrical projection  132  has a diameter equal to the inside diameter of the cylindrical member  122  and an axial length larger than the axial length of the cylindrical member  122 . 
     The press  120  further includes an upper plate  134  which is parallel to the lower plate  126  and which is bolted or otherwise fixed to a ram not shown. When the ram is vertically moved by a hydraulically operated cylinder, the upper plate  134  is moved with the ram. To the upper plate  134 , there is attached a cylindrical punch  136  through a punch retainer  138 , such that the lower portion of the punch  136  is engageable with the upper end portion of the cylindrical projection  132 . The cylindrical punch  136  has the same outside and inside diameters as the cylindrical members  122 . 
     The press  120  further includes an annular external pressure member  140  having an outside diameter equal to the diameter of the die hole  130 . The external pressure member  140  consists of an upper portion and a lower portion having a smaller inside diameter than the upper portion. The upper plate  134  has an annular stepped hole  141  consisting of an upper portion  142  and a lower portion  146  having a smaller outside diameter than the upper portion  142 . The upper and lower portions  142 ,  146  having the different outside diameters and the same inside diameter cooperate to define an annular shoulder surface  147  therebetween. The upper end section of the upper portion of the pressure member  140  extends through the lower portion  146  of the stepped hole  141 . An annular stop  144  having the same outside and inside diameters as the annular upper portion  142  of the stepped hole  141  is fixed to the upper end face of the upper portion of the pressure member  140  such that the annular stop  144  is slidably movable within the upper portion  142  of the stepped hole  141 . Namely, the external pressure member  140  is axially movable with the stop  144  relative to the upper plate  134  in the press-forming direction of the press  120 . 
     The lower portion of the pressure member  140  has an inside diameter equal to the outside diameter of the cylindrical member  122 , and an outside diameter equal to the diameter of the die hole  130 . The pressure member  140  is radially positioned relative to the upper plate  134  and the lower die  128  so that the lower portion of the pressure member  140  is engageable with the die hole  130 . A coil spring  148  is disposed in an annular space between the upper portion of the pressure member  140  and the cylindrical punch  136  such that the upper end of the coil spring  148  is held in contact with the lower surface of the upper plate  134  while the lower end of the coil spring  148  is held in contact with the annular shoulder surface defined between the upper and lower portions of the pressure member  140 . Thus, the coil spring  148  biases the pressure member  140  in the downward direction so that the annular stop  144  is normally held in contact with the annular shoulder surface  147 . When the upper plate  134  is lowered with the punch  136  and the pressure member  140 , toward the lower die  128  in which the cylindrical member  122  is fitted in the die hole  130  and on the central projection  132 , the pressure member  140  is brought into engagement with the outer circumferential surface of the cylindrical member  122 . Eventually, the pressure member  140  is brought into contact at its lower end face with the outward flange  154  of the cylindrical member  122 . After the pressure member  140  has been brought into contact with the outward flange  154 , the stop  144  is moved away from the shoulder surface  147 , with the coil spring  148  being compressed, as indicated in the right half of FIG.  13 . Thus, the external pressure member  140  and the spring  148  cooperate to function as a presser device  150  for holding the cylindrical member  122  in the die hole  130  while forcing the cylindrical member  122  onto the bottom surface  131  of the die hole  130 . 
     In operation of the press  120  constructed as described above, the cylindrical member  122  is set in the die hole  130 , in engagement with the central cylindrical projection  132 , and the upper plate  134  is lowered to move down the punch  136  by a predetermined distance so that an upper end face  152  of the cylindrical member  122  is lowered by a predetermined distance. The distance of this downward movement of the upper end face  152  is determined based on experimental data so that the diameter of the outward flange  154  which is originally equal to the inside diameter of 50 mm of the ring member  30  to be formed is increased to the outside diameter of 60 mm of the ring member  30 . That is, the application of an axial force from the punch  136  to the cylindrical member  122  in the plastic deformation step SB 1  causes the material of the lower end portion of the cylindrical wall of the member  122  to flow in the radially outward direction, so that the outside diameter of the outward flange is increased to the diameter of the ring member  30  to be obtained. 
     Then, the outward flange  154  of the cylindrical member  122  which has been subjected to the plastic deformation step SB 1  is subjected to the blanking or shearing step SB 2  on a shearing or blanking press, to punch out the ring member  30 . The steps SB 1  and SB 2  are repeatedly implemented to successively produce a plurality of ring members  30  using the same cylindrical member  122 . 
     While the presently preferred embodiments of this invention have been described above in detail by reference to the accompanying drawings, for illustrative purpose only, it is to be understood that the invention may be otherwise embodied. 
     Although the illustrated embodiments are adapted to produce the ring members  30  as the end product, the principle of the present invention is applicable to the production of intermediate products in the form of rings from which the ring members are obtained as the end products by a further blanking or shearing operation. 
     In the illustrated embodiments, the inward flange  39  of the cylindrical member  32  and the outward flange  154  of the cylindrical member  122  have a circular inner or outer profile, and the ring members  30  having circular inner and outer profiles (an annular transverse cross sectional shape) are produced by the plastic deformation of the cylindrical members  32 ,  122  and the blanking operation on the inward or outward flange  39 ,  154 . However, the inward or outward flange of the cylindrical member may have an elliptical or other transverse cross sectional shape, so that elliptical members and other annular members whose transverse cross sectional shape is not circular or is relatively complicated may be produced from the elliptical or otherwise-shaped flange of the cylindrical member. 
     In the first embodiment, the cylindrical container  36  is first prepared from the strip  10 , and then the cylindrical member  32  is prepared by removing a radially inner portion ( 41 ) of the bottom wall  34  of the cylindrical container  36 . However, the cylindrical member  32  having the inward flange  39  may be obtained by cutting a tubular member to obtain a tube having a desired length, and subjecting the end portion of the tube to a spinning operation or other plastic deformation to form the inward flange at one end of the tube. 
     Although the inward flange  39  and the outward flange  154  of the cylindrical members  32 ,  122  extend radially inwardly or outwardly of the cylindrical wall of the cylindrical members  32 ,  122 , that is, extend exactly perpendicularly with respect to the axis of the cylindrical members  32 ,  122 , the angle of the inward and outward flanges with respect to the axis of the cylindrical members may be other than 90°, provided the ring members  30  can be punched out from such inward or outward flange. 
     In the first embodiment, the original inside diameter (60 mm) of the inward flange  39  as formed by punching out the circular plate  41  is larger than the inside diameter (50 mm) of the ring member  30  to be formed, and this original inside diameter is reduced to the inside diameter of the ring member  30  in the first implementation of the plastic deformation step SB 1 . However, the original inside diameter of the inward flange  39  may be equal to the inside diameter of the ring member  30 . In this case, the blanking or shearing operation on the inward flange in the step SB 2  is implemented before the plastic deformation step SB 1 . Namely, the plastic deformation step SB 1  is implemented for the first time after the first ring member  30  is obtained. In this arrangement, the diameter of the circular plate  41  to be removed is smaller, so that the amount of wasting of the material is saved. 
     It is to be understood that the present invention may be embodied with various other changes, modifications and improvements, which may occur to those skilled in the art, without departing from the spirit and scope of the invention defined in the following claims: