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EP-3603844-B1 - AUTOMATIC DOMER POSITIONING IN A BODYMAKER

EP3603844B1EP 3603844 B1EP3603844 B1EP 3603844B1EP-3603844-B1

Inventors

  • FLEISCHER, KARL SCOTT
  • FOWLER, TRACY JAY

Dates

Publication Date
20260506
Application Date
20120514

Claims (13)

  1. A method for positioning a domer (18), said method comprising: determining a position of a punch (20), the punch being arranged on a reciprocating ram (14); receiving at a control system (54) the determined position of the punch; and if the punch is not concentrically aligned with a tool pack, controlling the control system (54) to determine a domer (18) target position signal, wherein said domer (18) target position signal includes data representing a target position for said domer (18); and sending said domer target position signal to a domer positioning assembly (56) to move said domer (18) to be in said target position; characterized in that : the determined position of the punch is: determined via a punch position sensor assembly (52) positioned about the reciprocating ram, and a position of the punch at a domer side of a last die (30C) in the tool pack and determined as the punch is retracted into the last die in the tool pack on a return stroke; and the target position being a position in which the domer would place the punch in a position to enter the tool pack in a concentric relationship with the last die.
  2. The method of Claim 1 wherein: said domer positioning assembly (56) includes a movable mounting assembly (62) and a drive assembly (64); said movable mounting assembly (62) structured to support said domer (18); and the method comprises causing said drive assembly (64) to move said movable mounting assembly (62).
  3. The method of Claim 2 wherein: said control system (54) includes a position tracking assembly (90), said position tracking assembly (90) structured to track the position of said domer (18) as said movable mounting assembly (62) moves and to provide a domer position signal, said domer position signal including data representing the position of said domer (18); and the method comprises causing said drive assembly (64) to receive said domer position signal and to arrest said drive assembly (64) when said domer (18) is disposed in said target position.
  4. The method of Claim 3 wherein: said movable mounting assembly (62) includes a first surface (70) and a second surface (72), said first and second surfaces (70, 72) being engagement surfaces; said drive assembly (64) including a first motor (80), a second motor (82), a first engagement device (84), and a second engagement device (86), each said motor (80, 82) having a rotating output shaft (81, 83), each said engagement device (84, 86) coupled to an associated motor output shaft (81, 83); said first motor drive shaft (81) having a threaded distal end (106); said second motor drive shaft (83) having a threaded distal end (108); each of said first and second engagement devices (84, 86) being a jack screw (110, 112) and a distal end (106, 108) said first jack screw distal end (106) coupled to said first surface (70); and said second jack screw distal end (108) coupled to said second surface (72) wherein the method comprises: causing each said engagement device (84, 86) to engage an associated engagement surface; causing each said jackscrew to engage one of said first or second drive shafts (81, 83); causing each said distal end to be coupled to one of said first or second surfaces (70, 72).
  5. The method of Claim 3 wherein: said movable mounting assembly (62) includes a mount assembly (170); said mount assembly (170) includes a first planar member (140) and a second planar member (142); said first surface (70) being on said first planar member (140); said second surface (72) being on said second planar member (142); said first planar member (140) movably coupled to said fixed mounting (60); and said second planar member (142) movably coupled to said first planar member (140), said second planar member second axis being substantially perpendicular to said first planar member first axis and substantially parallel to the plane defined by said first planar member (140); the method comprising: causing the first planar member (140) to translate over a first axis; and causing the second planar member (142) to translate over a second axis.
  6. The method of Claim 2 wherein: said domer positioning assembly (56) includes a fixed mounting; said fixed mounting (60) defining a rotational space (162) having an axis of rotation (164); said movable mounting assembly (62) includes a mount assembly (170) having a first substantially circular member (172) and a second substantially circular member (174); said first circular member (172) rotatably disposed in said rotational space (162) with the first circular member (172) center disposed substantially on said rotational space axis (164),; said second circular member (174) rotatably coupled to said first circular member (172), said second circular member (174) center being radially offset from said first circular member (172) center; and said drive assembly (64) having a first motor (80) and a second motor (82), each said motor (80, 82) having a rotating output shaft (81, 83), ; the method further comprising: causing said first circular member (172) to rotate about said rotational space axis of rotation (164); and causing each said motor output shaft (81, 83) to engage, and rotate, one of said first or second circular members (172, 174).
  7. The method of Claim 6 wherein said control system (54) includes a position tracking assembly (90), and the method comprises: causing said position tracking assembly (90) to track the position of said domer (18) as said mount assembly (170) moves and to provide a domer position signal, said domer position signal including data representing the position of said domer (18); and controlling said control system (54) to receive said domer position signal and to arrest said drive assembly (64) when said domer is disposed in said target position.
  8. The method of Claim 6 wherein: said first circular member (172) having a first engagement surface (70); said second circular member (174) having a second engagement surface (72); said drive assembly (64) including a first engagement device (84), and a second engagement device (86), each said engagement device (84, 86) disposed on an associated motor output shaft (81, 83); whereby motion from said first motor (80) is transferred to said first circular member (172) via the engagement of said first engagement device (84) with said first engagement surface (70); and whereby motion from said second motor (82) is transferred to said second circular member (174) via the engagement of said second engagement device (86) with said second engagement surface (72); the method comprising causing each engagement device (84, 86) to engage an associated engagement surface (70, 72).
  9. The method of Claim 8 wherein: said first engagement surface (70) is a toothed rack (176); said second engagement surface (72) is a toothed rack (178); said first engagement device (84) is a worm gear (180); and said second engagement device (86) is a worm gear (182).
  10. The method of Claim 6 wherein: said first circular member (172) includes a substantially circular opening, the center of said first circular member opening (190) being offset from the center of said first circular member (172); and said second circular member (174) is disposed rotatably within said first circular member opening (190).
  11. The method of Claim 10 wherein: the offset between said first circular member (172) center and said first circular member opening (190) center is between about 0.127mm and 0.508mm; and the offset between said second circular member (174) center and said domer center is between about 0.127mm and 0.508mm.
  12. The method of Claim 11 wherein: the offset between said first circular member (172) center and said first circular member opening (190) center is about 0.381mm; and the offset between said second circular member (174) center and said domer center is about 0.381mm.
  13. A can forming machine (10) comprising: a ram body (19), said ram body (19) being an elongated body with a longitudinal axis (26) and a distal end (24); an operating mechanism (12) structured to reciprocally move a ram body (19) between a first retracted position and a second extended position; a punch (20) disposed at said ram body distal end (24); a tool pack comprising a die assembly (16) with a last die (30C); a domer (18), said domer (18) defining a dome (46); a domer positioning assembly (56); and a control system (54); characterized in that the can forming machine comprises a punch position sensor assembly (52) positioned about the ram body (19) at the domer side of the last die; and wherein the control system is configured to: receive a determined position of the punch from the punch position sensor assembly, the determined position of the punch is a position of the punch at a domer side of the last die and determined as the punch enters into the last die on a return stroke; if the punch is not concentrically aligned with the tool pack, determine a domer (18) target position signal, wherein said domer (18) target position signal includes data representing a target position for said domer (18), the target position being a position in which the domer would place the punch in a position to enter the tool pack in a concentric relationship with the last die; and sending said domer target position signal to the domer positioning assembly (56) to move said domer (18) to be in said target position.

Description

BACKGROUND OF THE INVENTION Field of the Invention The disclosed concept relates generally to a system structured to position a domer assembly so that a reciprocating ram is substantially concentrically aligned with a die pack during the return stroke of a ram and, more specifically, to a positioning system structured to detect the position of the ram during the reciprocal motion and to move the domer assembly dynamically. Background Information Generally, an aluminum can begins as a sheet of aluminum from which a circular blank is cut. The blank is formed into a "cup" having a bottom and a depending sidewall. The cup is fed into a bodymaker which passes the cup through additional circular dies that thin and elongated the cup. That is, the cup is disposed in front of the punch mounted on an elongated ram. The ram is structured to reciprocate and pass the cup through the circular dies which (re)draw and iron the cup. That is, on each forward stroke of the ram, a cup is passed through the circular dies which further form the cup into a can body. On the return stroke, the now elongated can body is removed from the ram and a new cup is disposed thereon. Following additional finishing operations, e.g. trimming, washing, printing, etc., the can body is sent to a filler which fills the can with product. A top is then coupled to, and sealed against, the can body, thereby completing the can. More specifically, the die pack in the bodymaker has multiple, spaced dies, each die having a substantially circular opening. Each die opening is slightly smaller than the next adjacent upstream die. Thus, when the punch draws the cup through the first die, the redraw die, the aluminum cup is deformed over the substantially cylindrical punch. Because the openings in the subsequent dies in the die pack have a smaller inner diameter, i.e. a smaller opening, the aluminum cup is thinned as the ram moves the aluminum through the rest of the die pack. The space between the punch and the redraw die is typically less than about 0.254mm (0.010 inch) and less than about 0.102mm (0.004 inch) in the last ironing die. After the can has moved through the last die, the cup bottom and sidewall have the desired thickness; the only other deformation required is to shape the bottom of the cup into an inwardly extending dome. That is, the distal end of the punch is concave. At the maximum extension of the ram is a "domer." The domer has a generally convex dome and a shaped perimeter. As the ram reaches its maximum extension, the bottom of the can body engages the domer and is deformed into a dome and the bottom perimeter of the can body is shaped as desired; typically angled inwardly so as to increase the strength of the can body and to allow for the resulting cans to be stacked. As the ram withdraws, the can body then is stripped off of the end of the punch by injecting air into the center of the ram. The air comes out of the end of the punch and breaks the can body loose from the punch. Typically, there is also a mechanical stripper, which prevents the can body from staying on the punch it retracts back through the tool pack. The ram is withdrawn through the die pack, a new cup is deposited on the punch and the cycle repeats. The ram and the die pack are typically oriented generally horizontally. This orientation, however, allows for wear and tear on the punch. That is, the dies in the die pack must be separated so as to allow for the proper deformation of the cup. This means that the ram must extend horizontally through the entire die pack; a distance that may be anywhere from 457.2mm (18 inches) to 762mm (30 inches). This is also the stroke length for the bodymaker. This means that the ram is, essentially, a cantilevered arm. As is known, even a very rigid member supported as a cantilever will droop at the distal end. While this droop is generally not a problem for stationary members, the droop is a problem for a reciprocating ram passing through a die with a radial clearance of less than about 0.102mm (0.004 inch) between the punch and the die. Typically, the domer is statically aligned to the punch, in order to compensate for the droop, however this alignment may not be correct for the dynamics of the ram in the machine. Also, there are other factors that can cause the punch not to run concentrically to the machine center line. Thus, because of the droop and other reasons, the ram may not be concentric with the circular dies, i.e. ram is closer to, or in contact with, the lower portion of the die. Over time, the contact between the punch and the die causes either of both to become damaged. When this happens, the damaged parts must be replaced. Further, because this is a time consuming procedure, and because a typical can forming machine produces over 15,000 cans an hour, having a misaligned ram is a disadvantage. That is, if the ram is misaligned, it is unlikely that any cans will be made. The ram should be aligned to the centerline of the ma