Claims
- 1. A multi-stage die-forming method for necking-in the open end of a can body to form a reduced diameter neck having a smooth profile comprising the steps of:
- providing an open-ended can body having a sidewall of substantially cylindrical configuration about a longitudinal central axis, the sidewall defining an open end having a terminal edge;
- at one die-forming station, causing relative axial movement between a first necking-die and the open end of the sidewall to engage the first die against the sidewall to form a first reduced diameter neck having a first contoured portion extending inwardly from said sidewall to a first cylindrical portion terminating at said terminal edge;
- at a next die-forming station, causing relative axial movement between a second necking-die and the first neck to engage the second die against the first neck to form the first neck into a second reduced diameter neck having a second contoured portion extending inwardly from said sidewall to a second cylindrical portion terminating at said terminal edge, the diameter of the second cylindrical portion being less than the diameter of the first cylindrical portion;
- the second contoured portion having a first section extending inwardly from said sidewall at a minimum entrance angle of approximately 26.degree., a second radiused section joining said first section and curving away from said longitudinal axis on a radius substantially less than 0.900 inches, and a third radiused section curving away from said longitudinal axis and joining said second radiused section to said second cylindrical portion, the radius of said third section being substantially less than the radius of said second section, the angular distance through which said second section extends along the direction of said longitudinal axis being at least equal to the angular distance through which the third section extends, the sum of the angular distances being equal to said entrance angle; and
- at a subsequent die-forming station, causing relative axial movement between a third necking-die and the second neck to engage the third die against the second neck to form the second neck into a third reduced diameter neck having a third contoured portion extending inwardly from said sidewall to a third cylindrical portion terminating at said terminal edge, the diameter of the third cylindrical portion being less than the diameter of the second cylindrical portion, the third contoured portion having a profile which is substantially the same as the profile of said second contoured portion.
- 2. The die-forming method of claim 1, wherein the radius of said third section is within the range of 0.080 to 0.140 inches.
- 3. The die-forming method of claim 2, wherein the radius of said third section is 0.120 inches.
- 4. The die-forming method of claim 2, wherein the angular distance through which said third section extends does not exceed 12.degree..
- 5. The die-forming method of claim 2, wherein the radius of the second section does not exceed 0.500 inches.
- 6. The die-forming method of claim 5, wherein the radius of said second section is approximately 0.275 inches.
- 7. A multi-stage die-forming method for necking-in the open end of a can body to form a reduced diameter neck having a smooth profile comprising the steps of:
- providing an open-ended can body having a sidewall of substantially cylindrical configuration about a longitudinal central axis, the sidewall defining an open end having a terminal edge;
- at one die-forming station, causing relative axial movement between a first necking-die and the open end of the sidewall to engage the first die against the sidewall to form a first reduced diameter neck having a first contoured portion extending inwardly from said sidewall to a first cylindrical portion terminating at said terminal edge;
- at a next die-forming station, providing a second necking die having a contoured surface including a first section extending inwardly from said sidewall at a minimum entrance angle of approximately 26.degree., a second radiused forming section joining said first section and curving away from said longitudinal axis at a radius substantially less than 0.900 inches, and a third radiused forming section curving away from said longitudinal axis and joining said second radiused section to a cylindrical section, the radius of said third section being less than the radius of said second section, the angular distance through which said second section extends along the direction of said longitudinal axis being at least equal to the angular distance through which the third section extends, the sum of the angular distances being equal to said entrance angle, and causing relative axial movement between said second necking-die and the first neck to engage the first neck against the radiused forming sections of the second necking die to form the first neck into a second reduced diameter neck having a second contoured portion extending inwardly from said sidewall to a second cylindrical portion terminating at said terminal edge, the diameter of the second cylindrical portion being less than the diameter of the first cylindrical portion;
- at a subsequent die-forming station, providing a third necking die including a contoured surface having a profile which is substantially the same as the profile of the contoured surface of said second die and causing relative axial movement between said third necking-die and the second neck to engage the second neck against the contoured surface of the third die to form the second neck into a third reduced diameter neck having a third contoured portion extending inwardly from said sidewall to a third cylindrical portion terminating at said terminal edge, the diameter of the third cylindrical portion being less than the diameter of the second cylindrical portion.
- 8. The die-forming method of claim 7, wherein the radius of said third section is within the range of 0.080 to 0.140 inches.
- 9. The die-forming method of claim 8, wherein the radius of said third section is 0.120 inches.
- 10. The die-forming method of claim 8, wherein the angular distance through which said third section extends does not exceed 12.degree..
- 11. The die-forming method of claim 8, wherein the radius of the second section does not exceed 0.500 inches.
- 12. The die-forming method of claim 11, wherein the radius of said second section is approximately 0.275 inches.
- 13. A die-forming method for necking-in the open end of a can body to form a reduced diameter neck having a smooth profile comprising the steps of:
- providing an open-ended can body having a sidewall of substantially cylindrical configuration about a longitudinal central axis, the sidewall defining an open end having a terminal edge;
- at one die-forming station, providing a necking die having a contoured surface including a first section extending inwardly from sidewall at an entrance angle, a second radiused forming section joining said first section and curving away from said longitudinal axis at a radius substantially less than 0.900 inches, and a third radiused forming section curving away from said longitudinal axis and joining said second radiused section to a cylindrical section, the radius of said third section being less than the radius of said second section, the angular distance through which said second section extends along the direction of said longitudinal axis being at least equal to the angular distance through which the third section extends, the sum of the angular distances being equal to said entrance angle; and
- causing relative axial movement between the necking die and the open end of the sidewall to engage the sidewall against the radiused forming surfaces of the die to form a reduced diameter neck having a contoured portion extending inwardly from said sidewall to a cylindrical portion terminating at said terminal edge.
- 14. The die forming method of claim 13, comprising a subsequent die forming station, providing a second necking die including a contoured surface having a profile which is substantially the same as the profile of the contoured surface of the first die and causing relative axial movement between the second necking die and the first neck to engage the first neck against the contoured surface of the second die to form the first neck into a second reduced diameter neck having a second contoured portion extending inwardly from the sidewall to a second cylindrical portion terminating at said terminal edge, the diameter of the second cylindrical portion being less than the diameter of the first cylindrical portion.
- 15. The die-forming method of claim 14, wherein the radius of the third section is within the range of 0.080 to 0.140 inches.
- 16. The die-forming method of claim 15, wherein the radius of said third section is 0.120 inches.
- 17. The die-forming method of claim 15, wherein the angular distance through which said third section extends does not exceed 12.degree..
- 18. The die-forming method of claim 15, wherein the radius of the second section does not exceed 0.500 inches.
- 19. The die-forming method of claim 18, wherein the radius of said second section is approximately 0.275 inches.
- 20. A die-forming method for necking-in the open end of a can body to form a reduced diameter neck having a smooth profile comprising the steps of:
- providing an open-ended can body having a sidewall of substantially cylindrical configuration about a longitudinal central axis, the sidewall defining an open end having a terminal edge;
- at one-die forming station, providing a necking die having a multi-radiused forming surface, each successive radius from the entrance to the exit of the die being smaller than the previous radius and the angle through which each successive radius extends being equal to or smaller than the angle of the previous radius, the sum of the angular distances through which all the radii extend being substantially equal to the angle of tangency with which the leading edge of the can wall engages the entrance radius of the die; and
- causing relative axial movement between the necking die and the open end of the sidewall to engage the sidewall against the multi-radiused forming surface of the die to form a reduced diameter neck having a contoured portion extending inwardly from said sidewall to a cylindrical portion terminating at said terminal edge.
- 21. The die-forming method of claim 20, wherein the angle of the exit radius does not exceed 12.degree..
- 22. The die forming method of claim 20, comprising a subsequent die forming station, providing a second necking die including a multi-radius forming surface having a profile which is substantially the same as the profile of the forming surface of the first die and causing relative axial movement between the second necking die and the first neck to engage the first neck against the forming surface of the second die to form the first neck into a second reduced diameter neck having a second contoured portion extending inwardly from the sidewall to a second cylindrical portion terminating at said terminal edge, the diameter of the second cylindrical portion being less than the diameter of the first cylindrical portion.
RELATED APPLICATIONS
This application is a continuation-in-part of copending application Ser. No. 08/591,877, filed Jan. 25, 1996, which is a continuation-in-part of application Ser. No. 08/320,999, filed Oct. 11, 1994, now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3845653 |
Hilgenbrink |
Nov 1974 |
|
4519232 |
Traczyk et al. |
May 1985 |
|
5355710 |
Diekhoff |
Oct 1994 |
|
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
591877 |
Jan 1996 |
|
Parent |
320999 |
Oct 1994 |
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