Patent Publication Number: US-9403203-B2

Title: Diameter-reduction apparatus for can-trunk, can-body holder, can-manufacturing apparatus, and diameter-reduction method for can-body

Description:
TECHNICAL FIELD 
     The present invention relates to a diameter-reduction apparatus for a can-trunk, a can-body holder, a can-manufacturing apparatus, and a diameter-reduction method for a can-body for performing a process of drawing a metal-can-body in a can-manufacturing process for a beverage-can packing soft drink, beer or the like therein. 
     Priority is claimed on Japanese Patent Application No. 2012-23950, filed Feb. 7, 2012, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     A bottle-can for beverage made of aluminum alloy material is made by, for example, forming a plate material punched into a circular shape into a dosed-end cylindrical shape by performing a drawing process, an ironing process and the like, and further performing a diameter-reduction process. 
     Patent Document 1 (PTL 1) describes a can manufacturing apparatus for performing a diameter-reduction process to a closed-end cylindrical can-body. This can manufacturing apparatus has a structure which reduces a diameter of a can-body by advancing diameter-reduction position of the drawing die near to the base pad by providing a guide ring on the drawing die for preventing a can-trunk from swelling out so as to move back respect to the drawing die. 
     Patent Document 2 (PTL 2) describes a manufacturing method and a manufacturing apparatus which reduces a diameter of a can-trunk by drawing. In this case, by repeating the diameter-reduction processes in steps with holding the can along an axis direction, it is possible to form a can having a shape of reducing diameter thereof toward a bottom side or an opening side. 
     CITATION LIST 
     Patent Literature 
     [PTL 1] Japanese Unexamined Patent Application, First Publication No. 2003-200235 
     [PTL 2] Japanese Unexamined Patent Application, First Publication No, 2004-188423 
     SUMMARY OF INVENTION 
     Technical Problem 
     In such a forming process of a bottle-can, it is required to enlarge a deformation dimension in one process such as long deformation along the can-axis or large deformation of the diameter. However, in order to enlarge the deformation dimension in one process, an indentation load (what is called a neck-forming load) for pushing the can-trunk into the drawing die is increased, so that a can-bottom may sink or the can-trunk may swell out. 
     In recently years, it is required to work in a nearer part to the can-bottom than before in order to form a variant-can having a shape with steps of reduced-diameter parts and expanded-diameter parts from the can-bottom to the opening part. 
     If the reduced-diameter part is formed in the vicinity of the can-bottom using the apparatus of PTL 1, according to the structure in which the guide ring is further receded by abutting on the base pad, the reduced-diameter part can be near to the bottom part. However, because the guide ring is provided between the base pad and the drawing die, the reduced-diameter part is away from the bottom part at a length of the guide ring. In order to bring the reduced-diameter part closer to the bottom part in this structure, it is necessary to shorten the length of the guide ring. On the other hand, if the length of the guide ring is too small, t is difficult to prevent the can-trunk from swelling and the like. Furthermore, because the guide ring and the drawing die are separated, the can-trunk is not clamped at a part between the guide ring and the drawing die, so that the can-body may swell. 
     When the apparatus of PTL 2 is used, a flange is formed on an opening part previous to a forming process of a can-trunk, although a diameter cannot be expanded after forming the flange; so that, the design is restricted. That is to say, because the can in which the flange is formed is held between the opening part and the bottom thereof along the axis, it is not possible to expand the diameter. Accordingly, the opening part has the smallest diameter in a part formed from the opening side; and the bottom part has the smallest diameter in a part formed from the bottom side. Therefore, it is not possible to manufacture the variant-can having a narrow part at a middle part. 
     The present invention is achieved in consideration of the above circumstances, and has an object to provide a variant-can having a narrow part in the vicinity of a bottom part by performing a diameter-reduction process to the vicinity of the bottom part for a trunk part of a can-body made of metal. 
     Solution to Problem 
     The present invention is a diameter-reduction apparatus for can-trunk for performing a diameter-reduction process on a trunk part of a can-body having a closed-end cylindrical shape with an open end, including: a can-body holder holding a bottom part of the can-body, which is provided with: a base pad abutting on the bottom part of the can-boy; and a first clamping-ring having substantially a cylindrical shape which clamps an outer circumference surface of a trunk part of the can-body at the bottom side and which moves back and forth relative to the base pad along a can-axis direction; a die unit for diameter-reduction provided with a die for a diameter-reduction process of the trunk part by moving back and forth with respect to the can-body holder along the can-axis direction; and a first clamping-ring moving device moving the first clamping-ring backward along the can-axis direction along with an advance of the die. 
     According to the diameter-reduction apparatus for can-trunk, along with the advance of the die, the first clamping-ring clamping the outer circumference surface of the trunk part of the can-body is retreated with respect to the base pad, so that the die can approach the bottom part of the can-body with clamping the outer circumference surface of the trunk part of the can-body; accordingly, the diameter-reduction can be performed to far as the vicinity of the bottom part. On the other hand, when processing the trunk part at the opening side than the first clamping-ring, the first clamping-ring is not moved and clamps the trunk part of the can-body at the bottom side so as to prevent elastic deformation by the process. Therefore, the thickness is prevented from being uneven caused by anisotropic of rolled material in the process of diameter-deformation. 
     In the diameter-reduction apparatus for can-trunk, it is preferable that: the first clamping-ring moving device have: a push-back device moving back the first clamping-ring by pushing back the first clamping-ring along with approach of the die with respect to the can-body holder; and a returning device returning the first clamping-ring to a position before moving back. Furthermore, it is preferable that the push-back device include a contact part which is provided on the die unit and abuts on a op end of the first clamping-ring. 
     In this case, by connecting the approach of the die with the retreat of the first clamping-ring physically, the die can be reliably moved to the vicinity of the bottom part. 
     In the diameter-reduction apparatus for can-trunk, it is preferable that the push-back device be a second clamping-ring which has substantially a cylindrical shape, is provided on the die unit, is protruded forward from the die toward the can-body holder, and clamps an outer circumference surface of the trunk part at an opening side; and a top end of the second clamping-ring be the contact part which abuts on the top end of the first clamping-ring. In this case, because the second clamping-ring is disposed in the vicinity of the die, the trunk part in the vicinity of the die can be effectively prevented from swelling. 
     In the diameter-reduction apparatus for can-trunk, it is preferable that the returning device be provided with an elastic member which is provided on the can-body holder and energizes toward the base pad. In this case, the first clamping-ring can be easily moved forward along with the retreat of the die unit after retreat by being pushed back by the contact part of the die unit when the can-body is formed. 
     In the diameter-reduction apparatus for can-trunk, the first clamping-ring moving device may have: a drive device which moves the first clamping-ring back and forth; and a control device which controls the drive device. In this case, for example, by using a sensor detecting a position of the die, an actuator and the like, the first clamping-ring can be timely moved back and forth without contacting the die to the first clamping-ring. 
     The present invention is a can-body holder holding a can-body having, closed-end cylindrical shape in which one end is open, including: a base pad which abuts on a bottom part of the can-body; and a clamping ring having substantially a cylindrical shape, which clamps an outer circumference surface of the trunk part at the bottom side of the can-body and moves back and forth relative to the base pad along a can-axis direction. 
     The present invention is a can-manufacturing apparatus processing a can-body having a closed-end cylindrical shape in which one end is open, including: a plurality of the can-body holders; at least one processing-die unit which forms a trunk part of the can-body by advancing and retreating along the can-axis direction with respect to the can-body holder; and a can-body holder moving device moving the can-body holder intermittently with respect to the processing-die unit, in which one or more of the processing-die unit is a diameter-reduction die unit for diameter-reduction process of the trunk part of the can-body. 
     In the can-manufacturing apparatus, it is preferable that a plurality of the processing-die units be provided; and one or more of the processing-die unit be a diameter-expansion die unit which expands a diameter of the trunk part of the can-body. 
     The present invention is a diameter-reduction method for a trunk part of a can-body having a closed-end cylindrical shape in which one end is open, having the steps of: clamping an outer circumference surface of a trunk part of a can-body at a bottom side using substantially a cylindrical clamping ring and holding a bottom part of the can-body; and moving back the clamping ring and press-fitting a die for diameter-reduction of the trunk part into the trunk part of the can-body by advancing from an opening part toward the bottom part of the can-body, so that a top end of the die reaches in a vicinity of the bottom part of the can-body and a diameter-reduction is processed on the trunk part from the opening part to the vicinity of the bottom part. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to provide a variant-can having a narrow part in the vicinity of a bottom part by performing a diameter-reduction process up to the vicinity of the bottom part on a trunk part of a can-body made of metal. 
    
    
     
       BRIEF DESCRIPTION OF DRAWING 
         FIG. 1  It is a cross-sectional view showing a state in which a can-body before forming is held in a diameter-reduction apparatus for can-trunk provided with a can-body holder according to an embodiment of the present invention. 
         FIG. 2  It is a partial enlarged cross-sectional view showing a vicinity of a top end of a die in the diameter-reduction apparatus for can-trunk shown in FIG. 
         FIG. 3  It is a cross-sectional view showing a state in which an opening part of the can-body is pushed into the die by advance of a die unit in the diameter-reduction apparatus for can-trunk shown in  FIG. 1 . 
         FIG. 4  It is a cross-sectional view showing a state in which a contact part is abutted on a top end of a first clamping-ring in the diameter-reduction apparatus for can-trunk shown in  FIG. 1 . 
         FIG. 5  it is a cross-sectional view showing a state in which the first clamping-ring is pushed back by the contact part and a trunk part of the can-body is formed up to a vicinity of a bottom part by the die in the diameter-reduction apparatus for can-trunk shown in  FIG. 1 . 
         FIG. 6  It is a cross-sectional view showing a state in which the trunk part of the can-body is extracted from the die by retreat of the die unit and the first clamping-ring is advanced with being energized by an elastic member in the diameter-reduction apparatus for can-trunk show in  FIG. 1 . 
         FIG. 7  It is a cross-sectional view showing a state in which the formed can-body is detached from a can-body holder in the diameter-reduction apparatus for can-trunk shown in  FIG. 1 . 
         FIG. 8  It is across-sectional view showing shapes of bottle-cans in processes manufacturing by a diameter-reduction apparatus for can-trunk according to the present invention. 
         FIG. 9  It is a cross-sectional view showing a state in which a can-body is held before diameter-expansion in a diameter-expansion apparatus for expanding the diameter of the can-body. 
         FIG. 10  It is a cross-sectional view showing a state in which a punch is pushed into the opening part of the can-body by advance of a die unit in the diameter-expansion apparatus for can-trunk shown in  FIG. 9 . 
         FIG. 11  It is a cross-sectional view showing a state in which a can-body before forming is held in a diameter-reduction apparatus for can-trunk provided with a second clamping-ring according to an embodiment of the present invention. 
         FIG. 12  It is a cross-sectional view showing a state in which an opening part of the can-body is pushed into a die by advance of a die unit and a contact part of the second clamping-ring is abutted on a top end of a first clamping-ring in the diameter-reduction apparatus for can-trunk shown in  FIG. 11 . 
         FIG. 13  It is a cross-sectional view showing a state in which the first clamping-ring is pushed back by the contact part and a trunk part of the can-body is formed up to a prescribed position from the opening part by the die in the diameter-reduction apparatus for can-trunk shown in  FIG. 11 . 
         FIG. 14  It is a cross-sectional view showing a state in which the die unit is retreated and the first clamping-ring is advanced with being energized by an elastic member in the Jo diameter-reduction apparatus for can-trunk shown in  FIG. 11 . 
         FIG. 15  It is a cross-sectional view showing a state in which the formed can-body is detached from a can-body holder in the diameter-reduction apparatus for can-trunk shown in  FIG. 11 . 
         FIG. 16  It is a front view schematically showing a can-manufacturing apparatus provided with the diameter-reduction apparatus for can-trunk shown in  FIG. 1 . 
         FIG. 17  It is a view taken along the line I-I in  FIG. 16 . 
         FIG. 18  It is a cross-sectional view showing another embodiment of a first clamping-ring moving device. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Below, an embodiment of a can-body holder, a diameter-reduction apparatus for can-trunk and a can-manufacturing apparatus according to the present invention will be explained referring to drawings. A diameter-reduction apparatus  10  for can-body of the present embodiment is provided with a can-body holder  20  according to the present invention and performs a diameter-reduction on a trunk part  102  of a can-body  100  having a closed-end cylindrical shape with an open end. It can be utilized for so-railed a DI-can, a 3-piece can in which a bottom part is wound and closed, an impact-can or the like as the closed-end cylindrical shape with one open end. 
     As shown in  FIG. 1 , the diameter-reduction apparatus  10  for can-trunk provided with the can-body holder  20  holding the can-body  100  and a die unit  60  for diameter-reduction having a die  70  performing diameter-reduction on the can-body  100 . In this diameter-reduction apparatus  10  for can-trunk, the die  70  works in the trunk part  102  of the can-body  100  by moving the die unit  60  back and forth with respect to the can-body holder  20  along a can-axis direction. 
     The can-body holder  20  is provided with a base pad  30  abutting on a bottom part  101  of the can-body  100  and a first clamping-ring  40  having substantially a cylindrical shape which clamps an outer circumference surface of the trunk part  102  of the can-body  100  at the bottom part  101  side. The base pad  30  is formed annularly by elastic material such as rubber or the like, and held on a top surface of a base-pad holder  31  having substantially a cylindrical shape. 
     A back end of the base-pad holder  31  is fixed on a base-pad holder plate  32 . A columnar cavity is formed in the base-pad holder  31 . In the cavity, a plunger  23  is set so as to move back and forth by air introduced or evacuated through an air passage  32   a  formed in the base-pad holder plate  32 . 
     The first clamping-ring  40  is formed substantially cylindrically so as to be inserted the can-body  100  therein; and a bottom part thereof is closed by the base pad  30  and the plunger  23  and an inner circumference surface thereof is fitted with an outer circumference surface of the base-pad holder  31 , so that the first clamping-ring  40  can move relatively back and forth with respect to the base pad  30  along the can-axis direction. On the clamping ring  40 , a spring (i.e., an elastic member or a returning device)  50  is provided so as to energize the first clamping-ring  40  and to advance with respect to the base pad  30 . That is to say, the first clamping-ring  40  is fitted on the outer circumference surface of a cylindrical part of the base-pad holder  31  and is held by a guide pin  22 , so as to move back and forth along the can-axis direction with being energized forward (i.e., a left side in the drawing) by the spring  50 . In the diameter-reduction apparatus  10  for can-trunk, the base pad  30  and the base-pad holder  31  can be formed integrally. 
     On the first clamping-ring  40 , an air-chucking unit  21  holding the can-body  100  with pressing is provided. The air-chucking unit  21  is expanded by air supplied from an air-supplying unit  24  which is provided so as to be connected to an air passage  40   a  radially penetrating the first clamping-ring  40 . As a result, the air-chucking unit  21  protrudes from the inner circumference surface of the first clamping-ring  40  toward the can-axis so as to press the can-body  100  which is held in the first clamping-ring  40  from the outer circumference surface toward the can-axis, so that the can-body  100  can be held. In the air-chucking unit  21 , the connection with the air supplying unit  24  is broken by retreat of the first clamping-ring  40 , so that the pressure to the can-body  100  is released. 
     The die unit  60  opposite to the can-body holder  20  is provided so as to move back and forth with respect to the can-body holder  20 , and has: the die  70  including an outer die  71  and an inner die  72  which are provided in a concentric double cylindrical state; a columnar core  73  which is fitted inside the die  70 ; and a closed-end cylindrical die holder  80  holding the die  70  and the core  73 . 
     The core  73  has a flange part  73   a  which abuts on a bottom surface  80   a  of the die holder  80  and fits in an inner circumference surface  80   b  of the die holder  80 . The core  73  is held in a state of being located so that an axis corresponds to that of the die holder  80  by titling the flange part  73   a  into the die holder  80 . The flange part  73   a  and a columnar part  73   b  are provided coaxially with each other on the core  73 . An air passage  73   c  is formed so as to penetrate the flange part  73   a  and the columnar part  73   b . The air passage  73   c  opens at a top end surface of the columnar part  73   b  and is connected to an air passage  80   c  formed in the die holder  80 , so that air is supplied from an external air-supplying device (not illustrated) and can flow in the air passage  73   c.    
     The outer die  71  constructing the die  70  is held by being fitted to the inner circumference surface  80   b  of the die holder  80  and abutting on the flange part  73   a  of the core  73  in a positioning-state with respect to the die holder  80 . The inner die  72  is held by being fitted to the columnar part  73   h  of the core  73  and abutting on the flange part  73   a  of the core  73  in a positioning-state with respect to the core  73 . 
     As shown in  FIG. 2 , an outer circumference surface  72   a  of the inner die  72  is formed straight extending along the can-axis direction. An inner circumference surface  71   a  of the outer die  71  which is fitted to an outer side of the inner die  72  is formed so as to have an inner diameter in which only an end thereof is large. Accordingly, between the inner circumference surface  71   a  of the outer die  71  and the outer circumference surface  72   a  of the inner die  72 : a cylindrical introducing part s 1  comparatively wide is formed at the end part; and a narrow cylindrical gap s 2  is formed subsequently to the introducing part s 1  at a most part except the end part. That is to say, in the die  70 , a diameter of the trunk part  102  of the can-body  100  is reduced by being press-inserted through the introducing part s 1  into the cylindrical gap s 2  while being deformed so as to follow the inner circumference surface  71   a  of the outer die  71 . 
     In the die unit  60 , a contact part  61  is provided at the end of the outer die  71  so as to abut on the end of the first clamping-ring  40 . When the die unit  60  is approached the can-body holder  20 , the contact part  61  pushes the first clamping-ring  40  toward the bottom part  101  of the can body  100 , so that the first clamping-ring  40  is retreated while advancing the end of the die  70  to the vicinity of the bottom part  101  of the can-body  100 . As a result, the trunk part  102  of the can-body  100  can be formed by diameter-reduction to far as the vicinity of the bottom part  101 . 
     It will be explained that the can-body  100  is formed by the can-body holder  20  and the die unit  60 , referring the drawings. First, as shown in  FIG. 1 , in a state in which the can-body holder  20  and the die unit  60  are separated, while clamping the outer circumference surface of the trunk part  102  of the can-body  100  at the bottom part  101  side by using the first clamping-ring  40 , the bottom part  101  of the can-body  100  is held on the can-body holder  20 . The can-body  100  is positioned by a cylindrical inner surface of the first clamping-ring  40  and held by the air-chucking unit  21  pushing the vicinity of the bottom part  101  of the trunk part  102  of the can-body  100  by supply of the air through the air-supplying unit  24 . 
     Next, while moving the first clamping-ring  40  backward, the die  70  performing the diameter-reduction of the trunk part  102  is advanced from an opening part  103  toward the bottom part  101  of the can-body  100  and press-inserted into the trunk part  102  of the can-body  100 . 
     That is to say, as shown in  FIG. 3 , by advancing the die unit  60  from the opening part  103  toward the bottom part  101  of the can-body  100  and press-inserting the trunk part  102  of the can-body  100  through the introducing part s 1  into the cylindrical gap s 2  between the outer die  71  and the inner die  72  of the die  70 , the diameter-reduction is performed on the trunk part  102 . At this time, air is supplied into the can-body  100  from an external air-supplying device (not illustrated) through the air passage  73   c  formed in the core  73  and the air passage  80   c  formed in the die holder  80 , so that the inside of the can-body  100  is maintained at a positive pressure. 
     Furthermore, the die  70  is advanced so that the diameter-reduction position is near the bottom part  101  of the can-body  100 , so that the contact part  61  is abutted on the end of the first clamping-ring  40  (refer to  FIG. 4 ), and then the first clamping-ring  40  is pushed backward (refer to  FIG. 5 ). At this time, because the air-chucking unit  21  and the air-supplying unit  24  are disconnected by the retreat of the first clamping-ring  40 , the pressure-holding by the air-chucking unit  21  is released, so that the first clamping-ring  40  is not prevented from moving. While the diameter-reduction is performed, the trunk part  102  of the can-body  100  is clamped by the first clamping-ring  40  at the outer circumference surface thereof, so that the deformation such as the swell out of the trunk part  102  and the like is prevented. 
     After the diameter-reduction on the trunk part  102  to the vicinity of the bottom part  101  of the can-body  100  by press-inserting the die  70  into the trunk part  102  of the can-body  100  by advancing the die  70  while moving the first clamping-ring  40  backward, the die  70  is retreated as shown in  FIG. 6 . At this time, because the die  70  is retreated, the first clamping-ring  40  which is energized forward (i.e., toward the left in the drawing) by the spring  50  is advanced and returned to the previous position before the retreat, the air-chucking unit  21  is connected to the air-supplying unit  24 , and it is possible to pressure-hold the can-body  100  by the air-chucking unit  21  again. 
     When the die  70  is retreated, because the inside of the can-body  100  is maintained at the positive pressure by the air supplied from the external air-supplying device (not illustrated) through the air passage  73   c  formed in the core  73  and the air passage  80   c  formed in the die holder  80 , the die  70  is not retreated when holding the can-body  100 , so that the can-body  100  is maintained as being held by the can-body holder  20 . 
     Then, if the can-body  100  is dismounted at this time, after the die  70  is separated from the can-body  100 , as shown in  FIG. 7 , the plunger  23  of the can-body holder  20  is advanced by supplying air through the air passage  32   a  of the base-pad holder plate  32  so that the bottom part  101  of the can-body  100  is pushed, and a can-body  110  in which the diameter-reduction is performed to a prescribed diameter-reduction position A is dismounted from the can-body holder  20 . 
     As explained above, according to the diameter-reduction apparatus  10  for can-trunk of the present embodiment, because the first clamping-ring  40  clamps the outer circumference surface of the trunk part  102  at the vicinity of the bottom part  101  of the can-body  100 , the swell of the trunk part  102  at the vicinity of the bottom part  101  while the diameter-reduction can be prevented. Moreover, because the first clamping-ring  40  can be retreated with respect to the can-body  100 , the die  70  performing the diameter-reduction can be advanced to the vicinity of the bottom part  101  of the can-body  100 . Accordingly, it is possible to form the can-body  110  in which the diameter thereof is reduced from an opening part  113  to the diameter-reduction position A in the vicinity of a bottom part  111 . 
     Next, with respect to the can-body  110  which is performed the diameter-reduction on as above, by using a diameter-expansion apparatus  14  for can-trunk shown in  FIG. 9  and  FIG. 10 , a diameter-expansion is performed such as press-inserting a punch  170  having a larger external diameter than an inner diameter of the can-body  110  in the vicinity of the opening part  113 , so that a can-body  120  which is performed the diameter-expansion from an opening part  123  to a prescribed diameter-expansion position B can be obtained (refer to  FIG. 8 ). Because the diameter-expansion position B is nearer to the opening part  123  than the diameter-reduction position A, a trunk part  122  is constricted in the vicinity of a bottom part  121  in the can-body  120 . 
     The diameter-expansion apparatus  14  for can-trunk performing the diameter-expansion with respect to the can-body  110  in which the diameter-reduction is performed on the opening part  113  side than the diameter-reduced position A will be explained, but the common members to that of the diameter-reduction apparatus  10  for can-trunk are denoted by the same reference symbols in  FIG. 9  and  FIG. 10  and the explanation thereof are omitted. The diameter-expansion apparatus  14  for can-trunk is, as similar to the diameter-reduction apparatus  10  for can-trunk, provided with: a can-body holder  20  holding the can-body  110 ; and a die unit  160  for diameter-expansion having the punch  170  performing the diameter-expansion on the can-body  110 . In the die unit  160 , an outer die fitting an outer circumference surface of the trunk part  112  of the can-body  110  is not provided, but the punch  170  which is press-inserted into an inner circumference surface of the trunk part  112  is provided. 
     In the diameter-expansion apparatus  14  for can-trunk, the punch  170  has: a tapered part  170   a  expanding from a small-diameter end (right end in the drawing) toward a base end side (left side in the drawing); and a large-diameter part  170   b  at the base end side of the tapered part  170   a . A top end of the tapered part  170   a  is easily inserted into the can-body  110  because an outer diameter thereof is smaller than the opening part  113  of the can-body  110 . Furthermore, an outer diameter of the large-diameter part  170   b  is larger than the trunk part  112  of the can-body  110 , so it is possible to expand the trunk part  112  of the can-body  110  from the opening part  113  to the diameter-expansion position B by press-inserting the punch  170  into the can-body  110  from the opening part  113  until a right-end position of the large-diameter part  170   b  reaches the vicinity of the diameter-expansion position B ( FIG. 10 ). As a result, the can-body  120  in which the trunk part  122  is constricted from the diameter-reduction position A to the diameter-expansion position B in the vicinity of the bottom part can be obtained ( FIG. 8 ). 
     Next, with respect to the can-body  120  in which the diameter-reduction and the diameter-expansion are performed as above, by using a diameter-reduction apparatus  12  for can-trunk according to the embodiment of the present invention, as shown in  FIG. 11 , the diameter-reduction can be performed on the opening part  123  side than the diameter-expansion position B. The diameter-reduction apparatus  12  for can-trunk is provided with the can-body holder  20  having the first clamping-ring  40  and holding the can-body  120 , and a die unit  180  for the diameter-reduction having a die  70  performing the diameter-reduction on the can-body  120  as similar to the diameter-reduction apparatus  10  for can-trunk: however, it is different from the diameter-reduction apparatus  10  for can-trunk because the die unit  180  further has a second clamping-ring  90 . Below, the diameter-reduction apparatus  12  will be explained, but the common members to that of the diameter-reduction apparatus  10  for can-trunk are denoted by the same reference symbols and the explanation thereof are omitted. 
     In the diameter-reduction apparatus  12  for can-trunk, substantially the cylindrical second clamping-ring  90  provided at the die unit  180  protrudes forward (i.e., to right in the drawing) from the die  70  toward the can-body holder  20  so as to clamp the outer circumference surface of the trunk part  122  at the opening part  123  side. A contacting part  62  in the diameter-reduction apparatus  12  for can-trunk is an end of the second clamping-ring  90  and disposed so as to abut on the end of the first clamping-ring  40 . 
     When the diameter-reduction is performed on a part comparatively near the opening part  123  of the trunk part  122 , if using the diameter-reduction apparatus  10  for can-trunk, the die  70  is not advanced until the contacting part  61  abuts on the first clamping-ring  40 . Accordingly, the can-body  120  is worked in a state in which a part of the outer circumference surface of the trunk part  122  is not clamped, so that the deformation such as the swell out of the trunk part  122  may be occurred. Therefore, it is conceivable that a length of the first clamping-ring  40  along the can-axis direction is prolonged; however, it may be difficult to mount the can-body  120  on the can-body holder  20 . 
     On the other hand, in the diameter-reduction apparatus  12  for can-trunk, the length of the first clamping-ring  40  is not changed but the second clamping-ring  90  is attached to the die holder  80  so as to protrude forward from the die  70 , so that it is possible to perform the diameter-reduction in a state in which the second clamping-ring  90  clamps the outer circumference surface of the trunk part  122  of the can-body  120 . Furthermore, when the die unit  180  is advanced, the end of the second clamping-ring  90  abuts on the end of the first clamping-ring  40  ( FIG. 12 ), and pushes back the first clamping-ring  40  ( FIG. 13 ). Accordingly, a can-body  130  in which the trunk part  122  is constricted to a prescribed diameter-reduction position C while clamping a whole outer circumference surface of the trunk part  122  of the can body  120  can be obtained (refer to  FIG. 8 ). 
     After the diameter-reduction by advancing the die  70  to the prescribed position, the die  70  is retreated ( FIG. 14 ), the plunger  23  is advanced so as to push a bottom part  131  of the can-body  130 , so that the can-body  130  in which a trunk part  132  is constricted by the diameter-reduction from an opening part  133  to the diameter-reduction position C can be dismounted from the can-body holder  20  ( FIG. 15 ). By further process for the can-body  130 , a variant bottle-can  200  having a shape in which the vicinity of a bottom part is constricted as shown in  FIG. 8  can be obtained. 
     As explained above, according to the diameter-reduction apparatus  12  for can-trunk of the present embodiment, because the outer circumference surface of the trunk part  122  in the vicinity of the bottom part  121  of the can-body  120  is clamped by the first clamping-ring  40 , the trunk part  122  from the bottom part  121  to the vicinity of the diameter-expansion position B is prevented from swelling by the diameter-reduction. Therefore, elastic deformation of the bottom part  121  and the trunk part  122  at the diameter-reduction position A and the diameter-expansion position B by the diameter-reduction can be prevented, and a thickness of the can-body  120  can be prevented from being uneven caused by anisotropic of rolled material. 
     Since the second clamping-ring  90  is disposed in the vicinity of the die  70 , the trunk part  122  can be effectively prevented from swelling and the like even though deformation by the die  70  is comparatively large. Moreover, after the die unit  60  is retreated, the first clamping-ring  40  retreated by being pushed by the contacting part  62  of the die unit  60  while forming the can-body  120  is advanced by the spring  50  and can be returned to a previous position. 
     A can-manufacturing apparatus  300  having the diameter-reduction apparatuses  10  and  12  for can-trunk, the diameter-expansion apparatus  14  for can-trunk and the can-body holder  20  will be explained. The can-manufacturing apparatus  300  according to an embodiment of the present invention is provided with: a plurality of the can-body holders  20 ; at least one processing-die unit  322  which forms a trunk part of a can-body (i.e., a work W) having a closed-end cylindrical shape by advancing and retreating along the can-axis direction with respect to the can-body holder  20 ; and a can-body holder moving device (i.e., a driving unit)  330  which moves the can-body holder  20  intermittently with respect to the processing-die unit  322 . At least one of the processing-die units  322  is a diameter-reduction die unit  60  or  180  which performs the diameter-reduction on the trunk part of the can-body. 
     The can-manufacturing apparatus  300  is provided with, as shown in  FIG. 16  and  FIG. 17  more specifically, a work-holding unit  310  having a disk  311  in which the can-body holders  20  holding the works W are disposed circularly; a tool-holding unit  320  having a disk  321  in which the processing-die units  322  performing various processes on the works W are disposed circularly; and the driving unit  330  which drives the work-holding unit  310  and the tool-holding unit  320 . In this can-manufacturing apparatus  300 , as the processing-die units  322 , the diameter-reduction die unit  60  of the diameter-reduction apparatus  10  for can-trunk, the diameter-expansion die unit  160  of the diameter-expansion apparatus  14  for can-trunk, the diameter-reduction die unit  180  of the diameter-reduction apparatus  12  for can-trunk and the like are provided. 
     The driving unit  330  has a supporting shaft  331  supporting the disk  311  of the work-holding unit  310  and a supporting shaft  332  supporting the disk  321  of the tool-holding unit  320  coaxially with each other. In the driving unit  330 , the can-body holders  20  can be carried along a circumferential direction of the disk  311  by rotating the supporting shaft  331  intermittently. Moreover, by moving the supporting shaft  332  back and forth along the axis direction, the processing-die units  322  (the die units  60 ,  160 , and  180 ) can be moved back and forth along the can-axis direction with respect to the can-body holders  20 . The intermittent rotation of the supporting shaft  331  by the driving unit  330  is set so as to be stopped at a position in which each of the can-body holders  20  faces the processing-die units  322  respectively. 
     As shown in  FIG. 17 , in the can-manufacturing apparatus  300 , to each of the can-body holders  20  of the work-holding unit  310 , the closed-end cylindrical work W (the can-body  100 ) made by DI forming is supplied sequentially by a supplying star-wheel  302  of a work-supplying unit  301 . The work W (the can-body \ 00  which is supplied is worked in various processes by the processing-die units  322  held by the tool-holding unit  320  while being carried by the work-holding unit  310  along the circumferential direction of the disk  311 . The work W (the can-body  200 ) which is worked in various processes is extracted sequentially from the can-manufacturing apparatus  300  by an extracting star-wheel  304  at a work-extracting unit  303 . 
     The work-holding unit  310  and the tool-holding unit  320  are disposed so that each of the can-body holders  20  and each of the processing-die units  322  face each other. Since the disk  311  holding the can-body holders  20  is rotated intermittently by the driving unit  330  via the supporting shaft  331 , the processing-die units  322  facing the works W being held are alternated. Moreover, since the disk  321  is moved back and forth by the driving unit  330  via the supporting shaft  332 , the processing-die units  322  are moved back and forth with respect to the work W along the can-axis direction, so that the works W are worked in the various processes. 
     In addition to the above die units  60 ,  160  and  180 , the tool-holding unit  320  is provided with a plurality of the processing-die units  322  for working according to the work steps, such as a plurality of necking-dies for shoulder part for performing diameter-reduction on an opening part of the work W (a neck-in process), a thread-forming tool for a mouth section, a curl-forming tool and the like. Those processing-die units  322  are sequentially disposed circularly along the circumferential direction on the disk  321  in order of the processes. 
     The intermittent stop positions of the rotation of the work-holding unit  310  (the disk  311 ) around the axis of the supporting shaft  331  are set so that the can-axis of each of the works W in which the opening part thereof faces the tool-holding unit  320  and a center axis of each of the processing-die units  322  are coincided respectively. By the intermittent rotation of the disk  311  by the driving unit  330 , each of the works W is carried rotationally to a position facing the processing-die unit  322  for a next process, and worked in the next process. 
     The can-body holder  20  has a structure moving back the first clamping-ring  40  clamping the outer circumference surface of the trunk part of the can-body at the bottom part side along the can-axis direction along with the advance of the processing-die unit  322 , as described above. Accordingly, the works W can be held without preventing the process on the vicinity of the bottom part of the work by advance of the processing-die units  322 . 
     That is to say, when the tool-holding unit  320  moves forward and approaches the work-holding unit  310 , each of the processing-die units  322  works in the work W for each of the processes; and the work-holding units  310  is moved rotationally so that each of the works W faces the processing-die unit  322  of the next process in a state in which the holding units  310  and  40  are separated. 
     As explained above, the processes are performed when the holding units  310  and  40  are near to each other, and then, separated and rotated. By repeating those processes, the work W is worked in various forming processes, so that a can-body having a desired shape can be obtained. 
     The present invention is not limited to the above-described embodiments and various modifications may be made without departing from the scope of the present invention. 
     For example, when performing the diameter-reduction on a part near to the opening part of the can-body, that is, when the die is not advanced to the vicinity of the bottom part of the can-body, it is not necessary to move the first clamping-ring of the can-body holder back; and it is possible to perform the diameter-reduction by the first clamping-ring with preventing the part near to the bottom part from the elastic deformation such as the swell. 
     In the above embodiment, a first clamping-ring moving device is utilized so that the push-back device (the die  70  and the second clamping-ring  90 ) moves the first clamping-ring  40  of the can-body holder  20  backward along with the advance of the processing-die unit (the die units  60  and  160 ), and a returning device (the spring  50 ) returns the first clamping-ring  40  to the previous position along with the retreat of the die units  60  and  160 . However, the first clamping-ring moving device is not limited to the structure pushing back by contact directly as the above embodiment. 
     For example, as shown in  FIG. 18 , a structure may be adopted being provided with a drive unit  190  moving the first clamping-ring  40  back and forth such as an actuator, and a control device  192  controlling the drive device  190 , in this case, the control device  192  can control the drive device  190  so as to drive the drive device  190  according to the back or forth position of the die units  60  and  180 . Accordingly, parts can be prevented from being damaged owing to the contact between the first clamping-ring  40  and the die  70 , for example. 
     INDUSTRIAL APPLICABILITY 
     It is possible to provide a variant-can having a narrow part in the vicinity of a bottom part by performing a diameter-reduction process up to the vicinity of the bottom part on a trunk part of a can body made of metal. 
     REFERENCE SIGNS LIST 
     
         
           10 ,  12  diameter-reduction apparatus for can-trunk 
           14  diameter-expansion apparatus for can-trunk 
           20  can-body holder 
           21  air-chucking unit 
           22  guide pin 
           23  plunger 
           24  air-supplying unit 
           30  base pad 
           31  base-pad holder 
           32  base-pad holder plate 
           32   a  air passage 
           40  first clamping-ring 
           40   a  air passage 
           50  spring (elastic member) (returning device) 
           60  (diameter-reduction) die unit (processing-die unit) 
           61 ,  62  contact part 
           70  die (push-back device) 
           71  outer die 
           71   a  inner circumference surface 
           72  inner die 
           72   a  outer circumference surface 
           73  core 
           73   a  flange part 
           73   b  columnar part 
           73   c  air passage 
           80  die holder 
           80   a  bottom surface 
           80   b  inner circumference surface 
           80   c  air passage 
           90  second clamping-ring (first clamping-ring moving device push-back device) 
           100 ,  110 ,  120 ,  130  can-body 
           101 ,  111 ,  121 ,  131  bottom part 
           102 ,  112 ,  122 ,  132  trunk part 
           103 ,  113 ,  123 ,  133  opening part 
           160  (diameter-expansion) die unit (processing-die unit) 
           170  punch 
           170   a  tapered part 
           170   b  large-diameter part 
           180  (diameter-reduction) die unit (processing-die unit) 
           190  drive device 
           192  control device 
           200  bottle-can 
           300  can-manufacturing apparatus 
           301  work-supplying unit 
           302  supplying star-wheel 
           303  work-extracting unit 
           304  extracting star-wheel 
           310  work-holding unit 
           311 ,  321  disk 
           320  tool-holding unit 
           322  processing-die unit 
           330  driving unit (can-body holder moving device) 
           331 ,  332  supporting shaft 
         s 1  introducing part 
         s 2  cylindrical gap 
         A, C diameter-reduction position 
         B diameter-expansion position 
         W work