Hydraulic cup holder

A hydraulic cup holder for use in a draw and iron can making press is disclosed. This cup holder produces increased pressure between the cup being reformed and its holding members, reducing the tendency for wrinkles to occur in reforming the cup into a can body.

BACKGROUND OF THE INVENTION 
The draw and iron (D&I) process for forming one-piece metallic can bodies, 
notably can bodies formed from aluminum alloys and steel, has become the 
dominant method for producing beverage containers for such products as 
beer and soft drinks. 
In this process, circular blanks are punched from sheet metal and drawn 
into shallow cups in a first apparatus, commonly known as a cup maker. 
These cups are then fed to a second apparatus, called a body maker or D&I 
press, where the cups are reformed by redrawing and ironing into their 
final container shape. 
Subsequently, the container bodies are trimmed, necked and flanged to their 
final size. 
In a continuing effort to reduce metal usage, weight and cost of the 
containers, container bodies have been designed to enable the containers 
to be formed from thinner sheet metal. For example, at one time aluminum 
alloy cans were formed from sheet metal having a thickness of about 
0.015". More recently, however, these containers are being formed from 
metal as thin as 0.0129". 
The decreased metal thickness, coupled with the increasing complexity of 
the bottom structure required for sufficient strength in the can, has led 
to a problem in can formation. The shallow cups entering the body maker 
are mechanically held against the leading edge of a redraw die by a cup 
holder positioned within the cup. A punch member passes through the cup 
holder, carrying the cup through the redraw die and a series of ironing 
dies, with the punch bottoming on a bottom former which, with the punch, 
forms the bottom surface structure of the container. The decreased metal 
thickness, coupled with the increased bottom structure complexity of 
modern cans, has produced wrinkles in the bottom structure of the 
container, due to slippage of the metal during the redraw operation. 
The known mechanical cup holders are limited in the pressure they can apply 
to the cup against the redraw die. This limitation results from the length 
of axial movement required for the cup holder unit, as well as the 
stresses placed on the cup holder unit by its mechanical linkages. 
It is thus a primary objective of the present invention to provide an 
improved cup holder mechanism for a can making body press which is capable 
of increasing the holding pressure of the cup holder during redrawing of 
the cup, thereby reducing substantially or eliminating wrinkles in the 
metallic containers formed therefrom. 
THE PRESENT INVENTION 
By means of the present invention, these desired objectives are obtained. 
The apparatus of the present invention comprises a cup holder unit for use 
in a can body making press formed as inner and outer sleeves. The outer 
sleeve is mechanically linked to and timed with the punch of the press. 
The inner sleeve, which has attached thereto the cup holder, is slideably 
mounted for axial movement within the outer sleeve. Movement of the inner 
sleeve within the outer sleeve is hydraulically controlled, with the 
hydraulic pressure supplying the pressure to hold the cup between the cup 
holder and the redraw die.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning now to the FIGURES, the cup holder unit of the present invention is 
shown in cross-sectional view in FIG. 1. The cup holder unit, identified 
generally as 1, is mounted for axial movement within a can body maker 
press (not shown), such as that shown in U.S. Pat. No. 3,751,962, the 
disclosure of which is incorporated herein by reference, and is mounted by 
means of mounting 10 to mounting bracket 12, which is in turn mounted 
through mounting 14 to a source of driving motion for the cup holder unit 
1. Thus, through normal mechanical linkage to a motor means (not shown), 
cup holder unit 1 moves along its axis. As shown, cup holder unit 1 is in 
its forwardmost position, with a cup 16 being firmly held between a cup 
holder 18 and the entrance surface to a redraw die 20. During operation of 
the D&I press, cup holder unit 1 moves axially rearwardly, permitting cups 
16 to be positioned in front of cup holder 18 and the unit 1 moves axially 
forwardly to hold cup 16 in place for redrawing. A punch 22 is mounted 
along the same axis as cup holder unit 1 and is timed in its movement with 
cup holder unit 1 by being mechanically linked to the same driving force 
for the press. As illustrated, punch 22 is moving axially forwardly and is 
about to force cup 16 through the redraw die 20. In the container-making 
press, punch 22 would next force the redrawn cup 16 through a series of 
ironing dies and against a bottom former, all of which are common in the 
art and not illustrated. Punch 22, at the completion of the formation of a 
container body, moves axially rearwardly, providing space for a new cup 16 
to fall into position. 
The cup holder unit 1 comprises an outer sleeve member 24 and an inner 
sleeve member 26. The outer sleeve member 24 may include an outer casing 
28. The outer sleeve 24 also includes a pair of fluid passageways 30 and 
32 therewithin. These passageways 30 and 32 are connected to a source of 
hydraulic fluid, for purposes that will be shown below, such as by boring 
34 in fluid communication with chamber 30 and a similar boring (not shown) 
in fluid connection with chamber 32. 
Inner sleeve 26 has mounted thereto, by means of mounting member 36, face 
place 38 and bolts 37 and 40, the cup holder 18. Additionally, inner 
sleeve 26 has mounted at the rear thereof back plate 42, which is bolted 
thereto by means of bolts 44. Thus, inner sleeve 26 is slideably mounted 
within outer sleeve 24, within the distances permitted by contact between 
back plate 42 and stop surface 46 of outer sleeve 24 in the forward 
direction and stop surface 48 of inner sleeve 26 and stop surface 50 of 
outer sleeve 24 in the rearward direction. A plurality of fluid seals 52 
are positioned between the sliding surfaces of sleeves 24 and 26, to 
prevent leakage of hydraulic fluid through the system, as will be 
described below. 
When hydraulic fluid under pressure is applied through boring 34 to chamber 
30, the fluid forces inner sleeve 26 forward, to the position shown in 
FIG. 1, and as restricted by stop surface 46 and back plate 42. Likewise, 
when pressurized hydraulic fluid is applied through chamber 32, inner 
sleeve 26 is forced rearwardly, with its rearward movement limited by stop 
surfaces 48 and 50. 
The hydraulic mechanism for operating the cup holder unit 1 is illustrated 
in FIG. 2. A sump 60 containing hydraulic fluid, such as oil, has its 
hydraulic fluid pumped therefrom through line 62 by means of a pump 64. 
Pump 64 forces the hydraulic fluid through line 66 and through an in-line 
hydraulic filter 68, which filter preferably filters out particles 10 
microns or more in size. The hydraulic fluid next passes through line 70 
to a one-way valve 72, which prevents hydraulic fluid from flowing 
backwardly through line 70, to maintain the hydraulic pressure in the 
system. The fluid continues its passage through line 74 and to a solenoid 
valve 76. The solenoid valve 76, when given the proper signal, connects 
line 74 with line 78 and line 100 with line 103 to transfer hydraulic 
fluid from chamber 32 to sump 60, with the hydraulic fluid in line 78 
passing a pressure switch 80 and flowing through lines 82, 84, 86 and 88, 
with line 86 being connected to inlet 34 of cup holder unit 1. Connected 
at the end of line 82 is a pressure accumulator 90, which controls the 
pressure of the fluid throughout the system, and which is adjusted, such 
as by pressurized nitrogen, to pressurize the system to a pre-selected 
level. Pressure switch 80 is set to the pre-selected pressure level for 
the system, which may range from about 200 to about 2,000 pounds per 
square inch, and, if pressure switch 80 sees an excess pressure, opens 
pressure relief valve 92, permitting hydraulic fluid to pass through line 
94 to sump 60, relieving the pressure within the system. Purge valve 96 is 
also provided to permit the hydraulic fluid within the system to be 
drained from the system through line 98. 
As described above, line 86 is connected to inlet 34. Thus, as illustrated, 
the hydraulic system is acting to move the inner sleeve 26 to its 
forewardmost position, as illustrated in FIG. 1. This will, of course, 
force hydraulic fluid which may be in chamber 32 out through its inlet to 
its connection with line 104 and to lines 102, 100 and 103. No fluid may 
pass in the reverse direction from line 78 and line 74 through one-way 
check valve 72, acting to maintain the pressure of the system. 
When it is desired to retract inner sleeve 26, solenoid valve 76 is given a 
signal and connects line 74 with line 100 and line 78 with line 103. In 
this manner, hydraulic fluid passes through lines 100, 102 and 104, and 
from line 104 into chamber 32, forcing sleeve 26 rearwardly, until stop 
surfaces 48 and 50 are in contact. Hydraulic fluid passing from chamber 30 
to inlet 34 and into lines 86 and 78 pass through line 103, which is now 
connected to line 78, and into sump 60. Purge valve 106, connected to line 
102, permits hydraulic fluid to exit the system through line 108 when 
required. 
In operation of the can making press, inner sleeve 26 is maintained in its 
forwardmost position, as shown in FIG. 1, throughout the can making 
process. Accumulator 90 is pressurized to provide an eternal pressure 
ranging between about 250 and 2,000 pounds per square inch, which when 
applied to surface 48 of inner sleeve 26, results in a force which may 
range between about 1,000 and 10,000 pounds. This is in contrast to the 
prior mechanical system, which was capable of a maximum of about 1,700 
pounds of force. 
The body maker is adjusted such that the forwardmost stroke of the cup 
holder unit 1 by its mechanical linkage through brackets 12 and 14, 
attempts to force cup holder unit 1 a slight distance forward in excess of 
that which is possible due to the positioning of the cup 16 between cup 
holder 18 and redraw die 20, for example, about 0.015". The inner sleeve 
26 will move backwardly that amount, against the hydraulic pressure in the 
unit 1, transferring this force to cup holder 18 and firmly holding cup 16 
against redraw die 20. As this occurs, punch 22 moves forward, pulling cup 
16 through redraw die 20, with the metal at the bottom of cup 16 wrapping 
about the nose of punch 22 without slippage or wrinkling thereof. 
The only time that it is necessary to retract inner sleeve 26 is when 
maintenance is required on the body maker, such as if a jam or other 
mechanical problem occurs in the system. In that case, solenoid valve 76 
reverses the hydraulic fluid flow in the system, forcing inner sleeve 26 
rearwardly. 
From the foregoing, it is clear that the present invention provides an 
effective means for reducing wrinkles in the formation of can bodies from 
shallow cups, which means are notable for their few moving parts and 
relative short movement of these parts. 
While the invention has been described with reference to certain specific 
embodiments thereof, it is not intended to be so limited thereby, except 
as set forth in the accompanying claims.