Patent Description:
Conventional DWI aluminum beverage cans are often formed by first drawing a flat, circular blank into a cup in a dedicated machine known as a cupper. The cup then is inserted into another machine known as a bodymaker where the cup undergoes a redrawing process before wall ironing.

In a conventional redrawing process in a bodymaker, the cup is reduced in diameter and increased in length. The redrawn cup typically includes a flat bottom, a short angled wall that extends from the flat bottom, and a cylindrical sidewall that extends an end of the short angled wall, as shown in prior art <FIG>.

Conventional redraw tooling incudes a punch assembly <NUM> that includes a center punch tool <NUM> and an annular punch sleeve <NUM> that pushes the cup through a die (not shown in the <FIG>). The die has a cylindrical bore that receives the center punch tool and punch sleeve.

Punch tool <NUM> has a nose <NUM> that contacts a bottom of the drawn cup. Nose <NUM> includes a tip <NUM> that is the distal-most portion of tool <NUM>. A nose outer surface <NUM> extends outwardly and rearwardly from tip <NUM>.

Punch sleeve <NUM> is typically ifs affixed to center punch tool <NUM> and includes a tapered punch sleeve nose <NUM> that is rearward (that is, in the direction of relative motion of the tooling assembly <NUM> during the redrawing operation) of punch tool tip <NUM> and at least a portion of punch tool nose outer surface <NUM>. A punch sleeve inner cylindrical surface <NUM> surrounds center punch tool outer cylindrical surface <NUM>.

<FIG> Illustrates the tooling after a cup has been redrawn. In this regard, the redrawn cup is an intermediate product that includes a bottom <NUM>, a redraw chine <NUM>, and a sidewall <NUM>.

After the redrawing process, the punch assembly <NUM> pushes the cup through a series of dies (that is, the ironing process) to reduce the thickness of the sidewall. At the end of the ironing process, a doming tool <NUM> (<FIG>) deforms the cup bottom <NUM> into the well-known dome on the bottom of a beverage can, which includes a dome and a base inner wall. A chine tool component <NUM> deforms redraw chine <NUM> into the well-known chine shape of commercial aluminum beverage cans.

Tooling having spring-supported parts is known in the art, which parts tend to perform a function of deforming the workpiece. The inventor however has identified problems that make wrinkling of the redraw chine more likely. First, the trend toward thinner aluminum blanks reduces the inherent ability of the material to resist wrinkling. Second, the trend toward lightweight beverage can ends (that is, the seamed-on component at the end opposite the base) having a smaller center panel diameter has resulted in a change in base configuration.

<CIT> describes a redraw tooling assembly and a method of manufacturing a beverage can.

According to first and second aspects of the invention there is provided a redraw tooling assembly as defined in claim <NUM> and a method of forming a metal can body as defined in claim <NUM>. Exemplary redraw tooling for a can bodymaker is also described which includes redraw tooling that includes a punch ring, which is positioned between the center punch tool and the the punch sleeve. The punch ring contacts the wall of the cup to inhibit or prevent wrinkling that can occur when redrawing the cup using thin metal blanks. The retractable punch ring preferably inhibits wrinkling without significantly deforming the chine wall, such as not leaving a groove or bow in the chine wall. The metal cups are an intermediate structure that is formed into a can body, such as a drawn and ironed beverage can body.

The punch ring is supported by a compliant support, such as a spring plate, or other spring structure, or resilient material, such as as an elastomer. The compliant support postitions the punch ring to contact the wall, preferably the angled wall, of the metal during redrawing. Later, after the wall ironing process, the compliant support can be deformed (as in spring compression or elastomer compression or in retracting one part relative to another) when the doming tool contacts the metal to form the dome.

Accordingly, a redrawing tooling assembly in a can bodymaker for redrawing a metal cup comprises: a center punch tool, a punch sleeve, a punch sleeve, and a compliant support.

The punch ring is concentric with the center punch tool, outboard of at least a portion of the center punch tool, and inboard of at least a portion of the punch sleeve. The punch ring has a contact surface that is radially located between the center punch tool forwardmost tip and the punch sleeve contact surface. The punch ring contact surface is adapted to contact the chine wall of the metal cup during the redraw process.

The compliant support is configured to axially position the punch ring contact surface to contact the chine wall of the metal cup during the redrawing process to inhibit metal wrinkling. The compliant support is deformable in response to the punch ring engaging doming tooling in the bodymaker, thereby enabling the punch ring to retract relative to the center punch tool.

Preferably, the compliant support extends circumferentially around a portion of the center punch tool and contacts a base of the punch ring to urge the punch ring forward. The punch ring can include (i) an angled contact surface configured to contact a chine wall of a can and (ii) an inboard shoulder that is urged against an undercut shoulder of the punch tool by the compliant support, and may include a punch ring undercut shoulder. The undercut shoulder is configured to contact a land surface of the punch sleeve in a fully retracted position of the punch ring.

Optionally, the compliant support is retained by a groove in the center punch tool and the compliant support bears on a portion of the center punch tool. The compliant support peferably is a spring plate. The compliant support may also include a resilient elastomer.

The punch tool has a forwardmost annular tip adapted for concentric contact with a base of a metal cup during the redraw process preferably such that the punch ring engages the metal cup after the center punch tool, and the punch sleeve engages the metal cup after the punch ring. The punch sleeve is concentric with the center punch tool and has a contact surface that is axially located rearward of the center punch tool forwardmost tip such that the metal cup has an angled chine wall therebetween during the redrawing process. The punch tool forwardmost tip preferably is forward (that is relative in an axial direction) of the contact surface of the punch ring contact surface such that the punch ring contact surface initially contacts the chine wall at the chine wall angled surface after the chine wall angled surface is formed by the action of the tooling.

Also described herein is a method of forming a metal can body includes the steps of redrawing a metal cup, ironing the sidewall, and forming a dome. The redrawing step includes contacting a bottom of the cup with a concentric center punch tool and contacting the chine wall of the metal cup with a punch ring, which has a compliant support, to inhibit wrinkling of the chine wall. This step reduces the diameter of the metal cup and forms an angled chine wall between the bottom of the metal cup and a sidewall of the metal cup. Preferably, the center punch tool contacts the metal cup before the punch ring contacts the metal cup such that the punch ring contacts the angled portion (that is, the angled portion of the chine wall is already formed in the base before the punch ring contacts it).

Alternatively, the punch ring may contact the cup base before the punch ring contacts the metal base. In this regard, in the embodiment in which the punch ring contacts the metal cup before the punch tool, the specification uses the phrase "contacts the chine wall" because the punch ring contacts the portion of the base that forms the chine wall. Accordingly, the punch ring may contact the flat chine wall of the cup, as distinguished from the angled chine wall.

The ironing step inludes ironing the sidewall by pushing the center punch tool through ironing rings. The doming step includes forming a dome in the bottom of the cup including contacting the bottom of the cup with doming tooling such that the doming tooling compresses the compliant support.

Preferably, the compliant support urges an inboard shoulder of the punch ring into contact with an undercut shoulder of the punch tool until, during the redrawing step until the punch ring retracts relative to the punch tool. Alternatively, the punch ring can be spaced apart from the undercut shoulder of the punch tool. Upon doming, the punch ring can retract until an outboard undercut surface of the punch ring contacts a land surface of the punch sleeve.

Redraw tooling <NUM> according to an embodiment of the present invention is adapted for use in a can body maker. The bodymaker preferably receives a cup and first performs a redrawing operation using redraw tooling <NUM>. Alternatively, the bodymaker may receive a flat blank and performs a drawing operation using tooling <NUM>.

Tooling assembly <NUM> is on the distal end of a ram. After the redrawing step, the ram pushes the tooling assembly and cup through a series of dies to iron the cup sidewall, and thus transforms the cup into a can body or container body. When the can body is a beverage can body and when the ram is at the end of its stroke, the can body is pushed into doming tooling to form the dome, standing ring, and chine, as will be understood by persons familiar with method for forming beverage can bodies. The doming process well known in the art.

Tooling asembly <NUM> includes a center punch tool <NUM>, a punch sleeve <NUM>, a punch ring <NUM>, and a compliant support, such as spring plate <NUM>. Center punch tool <NUM> has circular, ring-like punch tool nose <NUM> at its forwardmost or distal most end. Center punch tool <NUM> has a hollow recess (not shown in the figures) radially inboard of nose <NUM> to receive doming tooling during the doming operation. The distal end of punch tool nose <NUM> forms a nose tip <NUM> about which the standing ring of the beverage can base is formed, a nose outer surface <NUM> that extends radially outwardly and rearward or proximally from tip <NUM>, a cylindrical center punch tool outer surface or sidewall <NUM> that extends rearwardly from nose outer surface <NUM>. The diamater of the largest part of outer surface <NUM> is greater than the diameter of punch tool sidewall <NUM> such that an undercut shoulder <NUM> is formed. Punch sleeve <NUM> preferably is fixed relative to punch <NUM> such that the sleeve <NUM> and punch <NUM> move together in the bodymaker. Punch sleeve <NUM> includes a distal punch sleeve nose <NUM>, a punch sleeve inner cylindrical surface <NUM>, a distal or forward-facing stop surface or landing or shoulder contact surface <NUM>, a rounded or tapered surface <NUM>, a punch sleeve outer cylindrical surface <NUM>, a recess shoulder surface <NUM> and a punch sleeve cutout or recess <NUM>. A portion of punch sleeve inner cylindrical surface <NUM> is in contact with or corresponds to a portion center punch outer surface <NUM>. Sleeve inner surface <NUM> also includes a forward-facing shoulder <NUM> on which a proximal end of center punch <NUM> is located.

Punch sleeve outer cylindrical surface <NUM> extends distally (forwardly) to yield to angled or tapered surface <NUM> that extends to punch sleeve nose <NUM>. Forward-facing landing <NUM> as shown in the figures is flat and extends radially inwardly and recessed relative to nose <NUM>. The cylindrical or axial part of wall <NUM> and the radial part of wall <NUM> form recess or cutout <NUM>, which together with the outer surface <NUM> of the center punch tool form a recess to house the rear portion of ring <NUM> and spring plate <NUM>.

Punch ring <NUM> preferably has an overall ring-like shape and includes a nose <NUM>, an inboard shoulder <NUM>, an inner surface <NUM>, an angled surface <NUM>, an undercut shoulder <NUM>, an outer surface <NUM>, and a rear surface <NUM>. Punch ring inner surface <NUM> preferably is cylindrical and is in sliding contact with or corresponds to a distal surface of center punch outer surface <NUM>. Punch ring inner surface <NUM> extends distally to inboard shoulder <NUM>, which may be contact with punch tool shoulder <NUM>, as the compliant support urges punch ring <NUM> forward. Or punch ring inboard shoulder <NUM> may be spaced apart from punch tool shoulder <NUM>. Punch <NUM> extends distally from shoulder <NUM> to a rounded punch nose <NUM>. Angled surface <NUM> extends radially outwardly and rearwardly (or proximally) from nose <NUM> to an undercut and to (preferably) cylindrical punch ring outer surface <NUM>. Angled surface <NUM> in the embodiment shown in <FIG> is flat or linear.

Compliant support, such a spring plate <NUM>, has a radially inboard portion surface that extends around the circumference of punch tool outer surface <NUM>. Spring plate <NUM> is wavy around its circumference such that the crests <NUM> of the upper surface plate <NUM> contact the base or rear surface <NUM> of punch ring <NUM> and the lower surface of the troughs <NUM> contact the shoulder <NUM> of punch sleeve recess <NUM>. Crests <NUM> and troughs <NUM> retain plate <NUM> in punch sleeve recess <NUM>.

As explained below, an outboard portion of plate <NUM> can engage an inner wall of the punch. Spring plate <NUM> can have inboard and outboard clearance and spring properties according to the particular parameters desired for the application. Because spring plate <NUM> is compliant, punch ring <NUM> can be pushed rearwardly by the doming tooling assembly as explained more fully below. The compliant support my be formed in any configuration, and encompasses any complfiant material, such as an elastomer or other resilient material.

Referring to <FIG> to illustrate the operation of tooling <NUM> during a drawing or redrawing step, center punch nose <NUM> moves forward relative to cup <NUM> until it engages a bottom of the cup <NUM> to begin the drawing/redrawing process. <FIG> illustrates the first point A at which the tooling at punch nose <NUM> touches or engages the can bottom <NUM>. At this point, spring plate <NUM> urges punch ring base <NUM> to urge punch ring <NUM> forward such that punch ring inboard shoulder <NUM> is in contact with undercut shoulder <NUM> of punch tool <NUM>. Or punch ring <NUM> may be positioned such that punch ring inboard shoulder is spaced apart from undercut shoulder <NUM>.

Punch ring nose <NUM> or angled surface <NUM> is the second point of contact B with cup <NUM> during the drawing/redrawing process, as best shown in <FIG>. Sleeve nose <NUM> or angled surface <NUM> then contacts cup <NUM> at point C, as best illustrated in <FIG>. <FIG> shows the completed redrawing process, with cup <NUM> having bottom <NUM>, redraw chine <NUM>, and sidewall <NUM>. Bottom <NUM> is formed between center punch nose <NUM>, redraw chine is formed over punch ring nose <NUM>, punch ring contact surface <NUM>, punch sleeve nose <NUM>, and punch sleeve contact surface <NUM>. The sidewall <NUM> of cup <NUM> is formed over punch sleeve sidewall surface <NUM>. Throughout the processes shown in <FIG>, punch ring inboard shoulder <NUM> may be spaced apart from undercut shoulder <NUM> of punch tool <NUM> or may be in contact with undercut shoulder <NUM>.

Upon the end of the stroke of the ram that pushes body maker tooling <NUM>, doming tool <NUM> forms a dome on cup bottom <NUM> and chine tool <NUM> contacts redraw chine <NUM>. As chine tool <NUM> deforms redraw chine <NUM>, punch ring <NUM> is pushed backwards against the force of spring plate <NUM> until undercut shoulder <NUM> of punch ring <NUM> contacts land <NUM> of punch sleeve <NUM>, as chine <NUM> is approximately linear between punch sleeve surface <NUM> or <NUM> and the curved portion of punch tool <NUM> where a radial deformation of chine <NUM> is formed. Thus, punch ring <NUM> supports the metal of redraw chine <NUM> to diminish wrinkling during the redrawing operation, and also possbily during the ironing operations, and then punch ring <NUM> retracts or is displaced by the doming tooling to enable formation of the chine.

Referring to <FIG> to illustrate a second embodiment, tooling asembly <NUM>' includes a center punch tool <NUM>', a punch sleeve <NUM>', a punch ring <NUM>', and a compliant support. Center punch tool <NUM>' has circular, ring-like punch tool nose <NUM>' at its forwardmost or distal most end. Center punch tool <NUM>' has a hollow recess (not shown in the figures) radially inboard of nose <NUM>' to receive doming tooling during the doming operation. The distal end of punch tool nose <NUM>' forms a nose tip <NUM>' about which the standing ring of the beverage can base is formed, a nose outer surface <NUM>' that extends radially outwardly and rearward or proximally from tip <NUM>', a cylindrical center punch tool outer surface or sidewall <NUM>' that extends rearwardly from nose outer surface <NUM>', and circumferential recess, such as groove <NUM>' <NUM> formed in punch sidewall <NUM>'.

Punch sleeve <NUM>' preferably is fixed relative to punch <NUM>' such that the sleeve <NUM>' and punch <NUM>' to the extent that punch <NUM>' and sleeve <NUM>' move together in the bodymaker. Punch sleeve <NUM>' includes a distal punch sleeve nose <NUM>', a punch sleeve inner cylindrical surface <NUM>', a punch sleeve outer cylindrical surface <NUM>', and a punch sleeve cutout <NUM>'. A proximal portion of punch sleeve inner cylindrical surface <NUM>' is in contact with or corresponds to a portion of center punch outer surface <NUM>'. Sleeve inner surface <NUM> also includes a forward-facing shoulder on which a proximal end of center punch <NUM>' is located.

Punch sleeve outer cylindrical surface <NUM>' extends distally to yield to angled contact surface <NUM>'. A distal portion of punch sleeve <NUM>' has a greater diameter than that of a proximal portion of punch sleeve <NUM>' such that a cutout <NUM>' is formed, which together with the outer surface <NUM>' of the center punch tool forms a recess <NUM>' for receiving punch ring <NUM>'.

Punch ring <NUM>' preferably has an overall ring-like or cylindrical shape and includes a nose <NUM>', an inner surface <NUM>', an angled surface <NUM>', an outer surface <NUM>', and a recess <NUM>'. Punch ring inner surface <NUM>' preferably is cylindrical and is in sliding contact with or corresponds to a distal surface of center punch outer surface <NUM>'. Punch ring inner surface <NUM>' extends distally to rounded punch nose <NUM>'. Angled surface <NUM> extends radially outwardly and rearwardly from nose <NUM>' to (preferably) cylindrical punch ring outer surface <NUM>'. Angled surface <NUM>' in the embodiment shown in the figures is rounded or convex outward (that is, bulging). Punch ring recess <NUM>' is formed in an radially inboard portion of punch ring inner surface <NUM>'. In its rest state, punch ring recess <NUM>' has an upper and lower boundary walls that preferably are aligned with the corresponding upper and lower boundary walls of center punch recess <NUM>'. Alternatively, the upper and lower boundary walls of recesses <NUM>' and <NUM>' are not aligned, as the recesses <NUM>' and <NUM>' overlap and in direct communication when punch ring <NUM>' is in its rest position.

Compliant support, such a spring plate <NUM>', has a radially inboard portion <NUM>' that is located in center punch recess <NUM>' and a radially outboard portion <NUM>' that is located in punch ring recess <NUM>'. Spring plate <NUM>' is wavy around its circumference such that the crests <NUM>' of the upper surface plate <NUM>' contact the top boundary wall of recess <NUM>' and the lower surface of the troughs <NUM>' contact the lower boundary wall of recess <NUM>'. Crests <NUM>' and troughs <NUM>' retain plate <NUM>' in groove <NUM>'.

As explained below, outboard portion <NUM>' of plate <NUM>' engages the punch ring recess <NUM> such that spring plate <NUM>' locates punch ring <NUM>' in a desired position for diminishing wrinkles during the redraw process. Because spring plate <NUM>' is compliant, punch ring <NUM>' can be pushed rearwardly by the doming tooling assembly as explained more fully above. The compliant support my be formed in any configuration, and encompasses any compliant material, such as an elastomer or other resilient material. Preferably the complaint support bears on the center punch tool, which preferably encompasses the compliant support contacting or being supported by the center punch tool.

Referring to <FIG> to illustrate the operation of tooling <NUM>' during a drawing or redrawing step, center punch nose <NUM>' moves forward relative to cup <NUM>' until it engages a bottom of the cup <NUM>' to begin the drawing/redrawing process. <FIG> illustrates the first point A at which the tooling at punch nose <NUM>' touches or engages the can bottom <NUM>'. Punch ring nose <NUM>' or angled surface <NUM>' is the second point of contact B with cup <NUM>' during the drawing/redrawing process, as best shown in <FIG>. Sleeve nose <NUM>' or angled surface <NUM>' then contacts cup <NUM>' at point C, as best illustrated in <FIG> shows the completed redrawing process, with cup <NUM>' having bottom <NUM>', redraw chine <NUM>', and sidewall <NUM>'. Bottom <NUM>' is formed between cener punch nose <NUM>', redraw chine <NUM>' is formed over punch ring nose <NUM>', punch ring contact surface <NUM>', punch sleeve nose <NUM>', and punch sleeve contact surface <NUM>'. The sidewall <NUM>' of cup <NUM>' is formed over punch sleeve sidewall surface <NUM>'.

Upon the end of the stroke of the ram that pushes body maker tooling <NUM>', doming tooling forms a dome in the can and urges punch ring <NUM> rearward, as generally described for first embodiment tooling <NUM>. The doming tool forms a dome on cup bottom and chine tool contacts redraw chine. As the chine tool deforms redraw chine, punch ring <NUM>' is pushed backwards against the force of spring plate <NUM>'. Thus, punch ring <NUM>' supports the metal of redraw chine <NUM>' to diminish wrinkling during the redrawing operation, and also possbily during the ironing operations, and then punch ring <NUM>' retracts or is displaced by the doming tooling to enable formation of the chine.

The first and second embodiments <NUM> and <NUM>' are illustrated with the forwardmost point of the punch tool nose <NUM> located forward (that is, forward or relatively distal along an axial centerline of the tooling, without regard to radial position) of the forwardmost portion of the punch ring nose <NUM> such that tooling <NUM> and <NUM>' contacts the workpiece in the sequence at point A, then point B, then point C. The present invnetion is not limited to this configuration of tooling <NUM> and <NUM>' nor the order of contact with the workpiece.

Rather, the present invention encompasses a structure in which the forwardmost portion of the punch ringe nose is forward of the punch tool nose <NUM> such that the punch ring contacts the workpiece before punch tool <NUM> contacts the workpiece. For example, as shown in <FIG>, tooling 10a includes an alternative embodiment punch ring 16a. Punch ring 16a has an overall ring-like shape and includes a nose 60a, an inbaord shoulder 61a, an inner surface 62a, an angled surface 64a, an undercut shoulder 65a, an outer surface 66a, and elongate neck 69a, and a rear surface 70a. The base of punch ring 16a is made up of punch ring inner surface 62a, inboard shoulder 61a, and rear surface 70a, which are as described with respect to first embodiment punch ring <NUM>. Further, the head of the punch ring 16a is made up of nose 60a, angled contact surface 64a, and undercut shoulder 65a, which preferably have the same shape as corresponding structure of first embodiment punch ring <NUM>. The head of the punch ring 16a extends distally or forward from the base of punch ring 16a to form elongated neck 69a such that nose 60a is located forward of nose <NUM> of punch tool <NUM>. The punch tool <NUM> and punch sleeve <NUM> are as described for first embodiment tooling <NUM>.

Thus, the first portion of the tooling 10a that contacts a metal cup during redrawing is nose 60a of punch ring 16a, which then retracts against spring <NUM>. As will be understood by persons familiar with container tooling technology, spring <NUM> may be chosen to provide resistance for anti-wrinkling without significant deforming of the chine wall. The dimensions of recess <NUM> may be chosen to provide sufficient space for punch ring 16a to retract consistent with the structure and function described herein.

The second embodiment tooling <NUM> ' may also accept an alternative punch ring 16a' that extends forward of the punch tool nose <NUM>' according to the same principles described above for punch ring 16a. Punch ring 16a' is illustrated by dashed lines in <FIG>. The remainder of tooling <NUM>' may be configured to provide sufficient space for punch ring 16a' to retract (not shown in <FIG>) consistent with the structure and function described herein.

Claim 1:
A redrawing tooling assembly (<NUM>) for a can bodymaker for redrawing a metal cup, comprising:
a center punch tool (<NUM>) having a forwardmost annular tip (<NUM>) adapted for concentric contact with a base of a metal cup (<NUM>);
a punch sleeve (<NUM>) that is concentric with the center punch tool, the punch sleeve has a contact surface (<NUM>) that is axially located rearward of the center punch tool forwardmost tip such that the metal cup (<NUM>) has a chine wall (<NUM>) therebetween during the redrawing process; and
a punch ring (<NUM>) concentric with the center punch tool, the punch ring is outboard of at least a portion of the center punch tool and inboard of at least a portion of the punch sleeve, the punch ring has a contact surface (<NUM>) that is radially located between the center punch tool forwardmost tip and the punch sleeve contact surface; the punch ring contact surface is adapted to contact the chine wall of the metal cup during the redraw process; and
a compliant support (<NUM>) that is configured to axially position the punch ring contact surface to contact the chine wall of the metal cup during the redrawing process to inhibit metal wrinkling, the compliant support is adapted to retract in response to the punch ring engaging doming tooling of the bodymaker, thereby enabling the punch ring contact surface to retract relative to the center punch tool,
the redrawing tooling assembly being characterised in that the punch ring includes an undercut shoulder (<NUM>) on an outboard side.