CA1260770A - Pressure regulated hydraulic cup holder for container redrawing systems - Google Patents

Abstract

HYDRAULIC CUP HOLDER
ABSTRACT OF THE DISCLOSURE

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.

Description

2~77Vi ' HYDRAULI C CUP HOLDER
_ ~ACKGROUND OF THE INVENTION
The draw and iron (D6I) process for forming one-piece metallic can bodies, notably can bodies form~d f rom aluminum alloys and ~teel, has become the dominant ~ethod 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.
10 These cups are then fed to a second appara-tus, 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 th~ir 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 ~s thin as 0.0129~.
The decreased metal thickness~ coupled with the increasing complex~ty of the botto~ structure required for sufficient strength in the can, has led to a problam in can ~ormat~onO 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 ironlng dies, with the punch bottoming on a bottom former which, with ~he pun~h, forms the bottom 6urface structure of the container. The decreased metal thicknessr coupled with the increased bottom .

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structure complexity of modern cans~ has produced wrinkles ~n the botto~ stru~ture of the conta1ner ! due ~o sllpp~ge of the metal during the redraw operation.
The known mechanical cup holder~ are lim1ted in the pressure they can apply to the cup against the redraw die. This llmitation result~ from the length of axial movement required for the cup holder unlt, as well as the stresses placed on the cup holder unit by its ~echanical l'inkages.
It ls ~hus a primary objective of the present inventlon to provide an improved cup holder mechanism for a can making body press which is ~apable of in-creasing the holding pressure of the cup holder during redrawlng of the cup, thereby reducing substantially or eliminating wrinkles in the metallic containers formed therefrom.

THE PRESENT INVENTION
~y means of the present inve~tion, 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 lnner and outer sleeve~. The outer sleeve ls mechanically linked to and timed with the punch of the press. The inner sleeve, which has attached thereto the cup holder, is slideably mounted ~or axial ~ovement within the ~uter ~leeve. M~vement o the inner ~leeve within the outer sleeve is hydrau llcally controlled, with the hydraullc pressure ~up-plylng the pressure to hold the cup between the cup holder and the redraw die.

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BRIEF DESCRIPTION OF THE DRAWINGS

The apparatus of the present invention will be more fully described with reference to the FIGURES in which:
FIGURE 1 is a cross-sectional view of the cup holder mechanism of the present invention; and FIGURE 2 is a schematic drawing of the hydraulic system employed in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODTMENTS

Turning now to the FIGURES, the cup holder unit of the present invention is shown in cross-sectional view in FIGURE 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. Patent No. 3,751,962, and is mounted by means of mounting 10 to mounting bracket 12, which is in turn mounted through mounting 14 to a source o~ 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 ~irmly 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 i5 moving axially forwardly and i5 about to force cup 16 through the redraw die 20. In thP container-making press, punch 22 , ~Z6~7,~

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 ~or 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 passageway 30 and a similar boring (not shown) in fluid connection with passageway 32.

Inner sleeve 26 has mounted thereto, by means of mounting member 36, face place 3~ 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 dirertion. A plurality of fIuid 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 passageway 30, the fluid forces inner sleeve 26 forward, to the position shown in FIGUR~

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1, and as restricted by stop surface 46 and back plate 42. Likewise, when pressurized hydraulic fluid is applied through passageway 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 FIGURE 2. A sump 60 containing hydraulic fluid, sucb 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 ~iven the proper signal, connects line 74 with line 78 and line 100 with line 103 to transfer hydraulic fluid from passageway 32 to sump 60, with the hydraulic fluid in line 78 p2ssing a pressure switch 80 and flowing through lines 82, 84, ~6 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 swi_ch 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 12~f~, 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 forwardmost position, as illustrated in FIGURE 1. This will, of course, force hydraulic fluid which may be in passageway 32 out through its inlet to its connec~ion 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 passageway 32, forcing sleeve 26 rearwardly, until stop surfaces 48 and 50 are in contact~
Hydraulic fluid passing from passageway 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 FIGURE 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 4~ 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.

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. - lz6~77e) The body maker ls adjusted s~ch that the forwardmost stroke ~f the cup holder un~t 1 by its mechan~cal llnkage through brackets 12 and 14, attempt~
to force cup holder unit 1 a ~light distance orw~rd in exces6 of that whlch 15 possible due to the pos~tioning of the cup 16 between cup holder 18 and redraw die 20, for example, about 0.015~ The inner sleeve ~6 will move backwardly that amount~ agalnst the hydraulic pressure in the ~nit 1, transferring this force to cup holder 18 and firmly holding cup 16 against redraw die 20. As th~s occurs, punch 22 moves forward, pulling cup 16 through redraw die 20, with the metal a~ the bottom of cup 16 wrapping about the nose of punch 22 without slippage or wrln~ling thereof.
The only time that it is necessary to retract inner sleeve 26 is when maintenance is required on the body maker, such as i a jam or other mechanical prob-lem occurs in the systemO In that case, so}enoid valve 76 reverses the hydraulic fluid flow in the system, ~0 forcing inner sleeve 26 rearwardly.
From the foregoIng, it ls clear that ~he present ~nventlon provides an effectlve means for reducing wrinkles ln the ~ormatlon of can bodles from shallow cups, whlch means are notable ~or their few moving parts and relatlve short movement of these parts.
Whlle the inventlon has been described wlth reference to certaln BpeCifiC embodlments thereo~, it is not ~ntended to be so limlted thereby, except as set forth ln the accompanylng claims.
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Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A cupholder for use in a can making machine, said cupholder comprising an outer sleeve member, an inner sleeve member slidably mounted within said outer sleeve member, a cupholder member carried by said inner sleeve member, and hydraulic means for controlling the position of said inner sleeve member within said outer sleeve member and for providing a constant hydraulic force to said cupholder member, said hydraulic means comprising a pair of hydraulic fluid channels positioned within said outer sleeve member and communicating with fluid passageways between said outer sleeve member and said inner sleeve member, a source of hydraulic fluid, a pump, valve means for directing said hydraulic fluid to said fluid channels and means for controlling hydraulic fluid pressure at a constant, pre-selected level to provide said constant hydraulic force.

2. The cupholder of claim 1 wherein said means for controlling hydraulic fluid pressure level comprises a pressurized accumulator, a pressure switch and a pressure release valve.

3. The cupholder of claim 1 wherein said valve means for directing said hydraulic fluid comprises a solenoid valve.

4. The cupholder of claim 1 wherein said hydraulic means further comprises a filter.