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

1. 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, comprising:

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-body; 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 part 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, the die 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.

2. The diameter-reduction apparatus for can-trunk according to claim 1 , wherein the first clamping-ring moving device comprises:

a push-back device moving back the first clamping-ring by pushing down 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.

3. The diameter-reduction apparatus for can-trunk according to claim 2 , wherein the push-back device comprises a contact part which is provided on the die unit and abuts on a top end of the first clamping-ring.

4. The diameter-reduction apparatus for can-trunk according to claim 3 , wherein:

the push-back device is 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 part side; and

a top end of the second clamping-ring is the contact part which abuts on the top end of the first clamping-ring.

5. The diameter-reduction apparatus for can-trunk according to claim 2 , wherein the returning device is an elastic member which is provided on the can-body holder and energizes the first clamping-ring toward the base pad.

6. The diameter-reduction apparatus for can-trunk according to claim 1 , wherein the first clamping-ring moving device comprises:

a drive device which moves the first clamping-ring back and forth; and

a control device which controls the drive device.

7. A can-manufacturing apparatus processing a can-body having a closed-end cylindrical shape in which one end is open, comprising:

a plurality of can-body holders each holding the can-body, and each comprising:

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 a trunk part at the bottom pat side of the can-body and moves back and forth relative to the base pad along a can-axis direction, the can-manufacturing apparatus further comprising:

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 plurality of can-body holders intermittently with respect to the processing-die unit, wherein

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.

8. The can-manufacturing apparatus according to claim 7 wherein:

the at least one processing-die unit comprises processing-ie units, and at least one of the processing-die units is a diameter-expansion die unit which expands a diameter of the trunk part of the can-body.