US3537291A - Apparatus for and method of forming an end closure for a can - Google Patents

Description

3, 7 G. P. HAWKINS 3,537,291 v APPARATUS FOR AND METHOD OF FORMING AN END CLOSURE FOR A CAN .4 Sheets-Sheet 1 Filed Oct. '4. 1967 I NVE N TOR GERALD P HAWKINS BY $4M V 4 FIG.

HIS ATTORNEYS G. P. HAWKINS Nov. 3, 1970 APPARATUS FOR AND METHOD OF FORMING AN END CLOSURE FOR A CAN 4 Sheets-Sheet 2 Filed Oct. 4, 1967 FIG. 3

' INVENTOR GERALD P. HAWKINS FIG. 6

HIS ATTORNEYS Nov. 3, 1970- G. P. HAWKINS 3,537,291

APPARATUS FOR AND METHOD OF FORMING AN END CLOSURE FOR A CAN Filed oct. 4. 1967 4-sheets-sheet :5

60 I 17 17 15 X4 2; \y1\ M I I I I INVENTOR GERALD P HAWKINS BY /Q%.VKI FIG. 5

HIS ATTORNEYS Nov. 3, 1970. G. HAWKINS 3,537,291

APPARATUS FOR AND METHOD OF FORMING AN END CLOSURE FOR A CAN Filed Oct. 4.119s? 4 sheets-sheet 4 |-30210/A 5 51 g1 Z MM w 0/.54 v ,17 Y 7m I 5 1390 V Y .o054 I 85 16 fi 787 PM 4] \22 F I 7 2473p).

x W 104 /06 7 GERAEB mmmrvs F 9 v BY %K/u/ HIS ATTORNEYS United States Patent 3,537,291 APPARATUS FOR AND METHOD OF FORMING AN END CLOSURE FOR A CAN Gerald P. Hawkins, Richmond, Va., assignor to Reynolds Metals Company, Richmond, Va., a corporation of Delaware Filed Oct. 4, 1967, Ser. No. 672,894 Int. Cl. B21d 28/00, 22/00, 45/00 US. Cl. 72-336 13 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to an apparatus for and method of making a metal end closure for a cylindrical can wherein such end closure has a substantially frustoconical flange which is adapted to be fastened against a cylindrical wall of an associated cylindrical can to define a sealed fluidtight closure. The frustoconical flange is formed by the apparatus and method of this invention by a drawing operation which controls its configuration in a precise manner and assure that the entire end closure is formed to a more closely controlled configuration to enable mechanical handling of a plurality of such end closures.

BACKGROUND OF THE INVENTION It has been generally found that apparatus and methods which are presently used to make end closures, such as metal end closures of the type used on cylindrical beverage cans, for example, provide end closures having varying dimensional configurations, yet such end closures may be generally satisfactory in providing an acceptable closure. However, because of these varying dimensional configurations it has been very diflicult to provide reliable mechanical handling equipment for handling these metal end closures in a mas production beverage canning operation thereby increasing the overall cost of such canning operation.

SUMMARY This invention provides an improved apparatus for and method of making end closures such as metal end closures for cylindrical cans wherein such end closures are formed to precisely controlled configurations thereby enabling easy mechanical handling thereof. Further, this invention provides an improved apparatus for and method of forming precisely controlled end closures capable of accepting blank stock having difierent thicknesses yet without requiring adjustment of such apparatus or interruption of the forming operation.

Other details, uses, and advantages of this invention will become apparent as the following description of the embodiments thereof presented in the accompanying drawings proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings show a present preferred embodiment of this invention, in which:

FIG. 1 is a view with parts in section and parts broken away of an exemplary embodiment of the apparatus of this invention comprised of a punch and a cooperating die and showing such punch and die held apart prior to insertion of a strip of sheet metal stock therebetween;

FIG. 2 is a fragmentary sectional view showing the punch and die of FIG. 1 immediately after cutting a circular sheet metal blank from such strip of stock and prior to forming the blank to define an end closure for a can;

FIG. 3 is a fragmentary sectional view similar to FIG. 2 showing the cooperating punch and die of FIG. 1 partially urged together and at the commencement of a drawing operation used to form a substantially frustoconical Wall for such end closure;

FIG. 4 is a view with parts in section and parts broken away similar to FIG. 1 and showing the punch and die fully urged together with a formed end closure held in position therebetween;

FIG. 5 is a perspective view of the formed end closure of FIG. 4;

FIG. 6 is a greatly enlarged sectional view particularly illustrating the problem presented in forming a vertical wall of an end closure in an uncontrolled manner essentially as achieved using existing apparatus;

FIG. 7 is a greatly enlarged sectional view of the improved apparatus of this invention particularly illustrating its control surfaces used to precisely define the configuration of the substantially frustoconical wall of an end closure;

FIG. 8 is a view with parts in section and parts broken away illustrating the problem encountered in mechanically individually dispensing an end closure from a stack of end closures formed using existing apparatus and techniques; and

FIG. 9 is a view similar to FIG. 8 particularly illustrating a stack of controlled configuration end closures made in accordance with the apparatus and method of this invention showing the manner in which they may be individually dispensed in an efficient manner.

DESCRIPTION OF ILLUSTRATED EMBODIMENT An exemplary apparatus and method of this invention is illustrated in FIGS. 1-4 of the drawings and such apparatus and method is utilized to form a metal end closure designated generally by the numeral 15 and illustrated in FIG. 5 of the drawings.

End closure 15 has a flat substantially planar central portion of circular outline which is designated by the numeral 16 and a substantially frustoconical flange 17 which is adapted to be fastened in position within the end portion of an associated cylindrical can. Flange 17 is drawn to a precisely controlled configuration using the apparatus and method of this invention and as will be described in detail hereinafter. The upper peripheral edge of flange 17 blends smoothly into a top annular portion 18 defining a chime end for the associated can on which end closure 15 is fixed and a circumferential downwardly extending lip 19 extends from the outer edge of annular portion 18. Lip 19 engages the outer cylindrical surface of an associated can and cooperates with flange 17 to sandwich the associated end portion of such can therebetween in a known manner to provide a tight seal.

The apparatus illustrated in FIGS. l-4 is designated generally by the numeral 21 and comprises a die 22 which in this example of the invention is shown as a stationary die and a cooperating punch 23 which is adapted to be suitably moved toward and away from the die 22 in a known manner.

The exemplary die 22 comprises a fixed bed or base 24 which has a die head assembly 25 suitably supported thereon. The die head assembly 25 comprises a blanking member 26 which is suitably fixed by bolts 30 to a support pad 31 carried on bed 24. The blanking member 26 has a substantially circular cutting edge 32 which is used to cut a disc-like blank of circular outline in a manner as will 'be subsequently described.

The die head assembly 25 has a telescoping ring 33 of substantially L-shaped cross-sectional outline which is suitably resiliently supported by a plurality of telescoping pins, each designated by the same numeral 34, resiliently urged outwardly from the base 24. In this example of the invention each telescoping pin 34 is resiliently urged outwardly by an associated compression spring 35.

The die head assembly 25 has a first ring provided with V a convex outer edge 40 and ring 41 is fixed to support pad 31 by a plurality of bolts 46.

The die head assembly 25 has a central portion 42 which is fastened in position by bolts 43 and central portion 42 has a planar supporting surface 44 which is adapted to support the bottom surface of the central portion 16 of end closure 15 to be formed by die 22 in cooperation with punch 23. The die head assembly 25 has a first inclined control surface 45, see FIGS. 1 and 7, which is substantially frustoconical, adjoins, and extends inwardly and downwardly from the inner edge of convex edge or surface 40. Frustoconical surface 45 is adapted to cooperate with an associated surface on punch 23 to control the configuration of frustoconical flange 17 of end closure 15. The manner in which frustoconical surface 45 cooperates with an associated surface of punch 23 will be described in detail subsequently.

The punch 23 is supported for controlled movement toward and away from die 22 by vertical column assemblies each designated by the numeral 47 and of known construction. In addition, the means used to move punch 23 toward and away from the die 22 may be of any suitable known construction and therefore will not be shown or described in detail.

The punch 23 comprises a main support assembly 50 which has a punch head assembly 51 fixed thereto in a known manner. The punch head assembly 51 comprises a holding ring 52 which is supported by telescoping support pins 53 and urged resiliently outwardly by a compression spring 54 associated with each pin 53. The telescoping ring 52 is adapted to engage and hold a strip of sheet metal 56 in the manner illustrated in FIGS. 2-4 of the drawings by urging the strip 56 against the outer annular face of the blanking member 26 comprising die 22.

Punch head assembly 51 also comprises a second ring 60 which serves as a blanking punch and holding ring. The ring 60 has a second cutting edge defining its outer circumferential edge and designated generally by the numeral 61. The cutting edge 61 is of circular outline corresponding to the circular outline of the cutting edge 32 provided in the die head assembly 25. The ring 60 is fixed to the punch head assembly 51 using fastening bolts 63.

The ring 60 also has an inner circular edge 64 and the inner and outer circular edges 64 and 61 respectively of ring 60 define a bearing surface designated by the numeral 67. The bearing surface 67 is adapted to engage a peripheral annular strip or portion of a blank to be formed by apparatus 21 and urge such annular strip against telescoping ring 33 of die 22 in a manner to be described subsequently.

Punch head assembly 51 also has a knockout ring 65 which has a concave outer edge or surface 66 which is adapted to engage the end closure 15 at the bottom of the drawing stroke. The ring 65 is normally held up in the punch head assembly 51 by a telescoping rod 70 fixed to ring 65. The rod 70 and ring 65 are held upwardly by a spring 71. After forming an end closure 15 as shown in FIGS. 2-4 the punch 23 is moved away from die 22 and as such punch is moved away rod 70 strikes a cam operated'finger on apparatus 21 which compresses spring 71 and causes knockout ring 65 to engage and knock out the completed end closure 15.

The punch head assembly 51 also has a central portion 73 which is suitably fixed to support 50 through use of a support pad 74. Central portion 73 is fastened by a plurality of bolts 75 to support pad 74 which is in turn suitably fixed to support 50 of the punch 23. The central portion 73 has ,a substantially planar face 76 which is adapted to be aligned above and cooperate with surface 44 provided in the central portion 42 comprising the die head assembly 25.

The punch head assembly 51 also has second inclined surface 80' of substantially frustoconical configuration which is adapted to cooperate with the inclined frustoconical surface 45 to provide the substantially frustoconical flange portion 17 of the end closure 15 in a controlled manner. Frustoconical surface comprises the outer surface of a forming or draw ring 81 which is suitably fixed to central portion 73 of punch head assembly 51 for movement therewith toward and away from the die 22.

As seen particularly in FIGS. 2 and 3 of the drawings, upon moving the punch 23 toward the die 22 the ring 60 engages a peripheral annular strip of a circular sheet metal blank severed by cutting edges 32 and 61 and urges such annular strip around the outer circumferential edge of ring 41 to define lip 19 of end closure 15. The annular strip defining lip 19 is thus firmly clamped between rings 41 and 60 to hold the circular blank in position and enable a portion of such blank adjoining such annular strip to be drawn to form frustoconical flange 17 of end .closure 15 by further movement of the punch 23 toward the die 22.

Having generally described the cooperating components of the die 22 and the punch 23 the description will now proceed with a presentation to highlight the operation of apparatus 21 and the technique utilized to form the improved end closure 15 which is of accurately controlled configuration. As seen in FIG. 1 of the drawings, an elongated strip of sheet metal 56 is positioned immediately to the left of apparatus 21 and so that only a portion .thereof indicated at 82 is supported on blanking member 26 of die head assembly 25. The elongated strip of metal 56 is then moved to the right to the position shown in FIG. 2 and the punch 23 is then moved toward the die 22 while being guided by guide columns 47 whereby the cutting edge 32 of blanking member 26 cooperates with cutting edge 61 of ring 60 to sever a flat circular blank designated by the numeral 85.

As the punch and die are moved together the ring 60 urges the telescoping ring 33 carried in the die head assembly 25 inwardly and its inner edge 64 wipes the peripheral outer strip of the blank 85 around the top outer edge of the clamping ring 41 to thereby form circumferential downwardly extending lip 19 comprising the outer periphery of the end closure 15 and hold the partially formed blank 85 firmly in position as seen in FIG. 3.

Further movement of the die 22 and punch 23 toward each other to their innermost position illustrated in FIG. 4 results in the complete formation of the end closure 15 and upon subsequently moving the die 22 and punch 23 apart the knockout ring 65 knocks out the completed end closure 15.

The improved apparatus and method of this invention enables the forming of end closure 15 so that its frustoconical wall portion 17 and its peripheral lip 19 are formed to a dimensionally accurately controlled configuration. The detailed description will now proceed by referring to FIG. 7 of the drawings wherein a greatly enlarged fragmentary sectional view of the cooperating punch 23 and die 22 is illustrated with such punch and die shown in their innermost position which is the position of FIG. 4. The apparatus and method of this invention enable the precise forming of end closure 15 and in particular enable the drawing of frustoconical wall portion 17 in an accurate and controlled manner so that the final configuration of end closure 15 is accurately controlled and enables easy and eflicient subsequent mechanical handling thereof with minimum interruption of production.

The inclined surface 45 comprising the die head assembly 25 in this example of the invention is preferably a substantially frustoconical surface. Similarly, the cooperating inclined surface 80 provided on ring 81 of the punch head assembly 51 is also of a corresponding substantially frustoconical configuration as previously mentioned in both instances. The dimensional arrangement of such frustoconical surfaces is such that during the forming of an end closure 15, that portion of the circular blank 85 formed therebetween to define the frustoconical wall portion or flange 17 is held to a closely controlled configuration in a repeatable manner even under conditions wherein the elastic limit of a particular circular metal disc 85 being formed has not been exceeded.

It will be appreciated that informing an end closure 15 in the manner presented herein using essentially a drawing operation to form wall portion 17 that when the elastic limit of the metal used isnot exceeded there is a tendency for the metal to bounce back; i.e., attempt to partially return to its original condition, once the drawing forces are relieved. Accordingly, the configuration of the wall portion 17 would tend to assume something other than the desired configuration. However, by controlling the configuration of wall portion 17 between cooperating substantially frustoconical control surfaces such a tendency of the metal to bounce back is eliminated substantially and effectively.

As seen in FIG. 7 of the drawings the outer edge 40 of the ring 41 has a substantially outwardly or upwardly convex configuration as viewed in cross section by passing a sectioning plane through the central axis 89 of ring 41. The convex outer surface or edge 40 is defined by a compound surface having a central circular portion 92 adjoined on opposite ends thereof by oppositely arranged outer and inner circular portions designated respectively by the numerals 93 and 94 and each having a substantially smaller radius than the central circular portion 92. The radius of central circular portion 92 is designated by the numeral 92R.

The knockout ring 65 has a concave outer edge 66 when viewed in cross section and as determined by the above mentioned sectioning plane through axis 89. Concave outer edge 66 comprises a concave circular portion 95 which corresponds to central portion 92 and has a larger radius than the central circular portion 92, and such radius is designated by the numeral 95R.

Concave portion 95 is adapted to be aligned above the central portion 92 to clamp the circular blank 85 therebetween when the die 22 and punch 23 are at their innermost position and thereby accurately shape or form the top annular portion 18 of end closure 15. In addition, the larger radius of concave portion 95 assures that end closure 15 may be easily ejected from apparatus 21 once the particular end closure 15 has been formed.

The central edge portion 92 and the cooperating concave edge portion 95 are arranged in apparatus 21 so that their centers are arranged to lie on a straight line indicated generally by the numeral 100. Such straight line is positioned immediately adjacent to and parallel with a right circular cylindrical surface of revolution effectively bisecting the ring 41 comprising the die head assembly 25 and with the punch 23 moved fully against the die 22.

To provide more accurate control of the top chime defining portion 18 of the end closure 15 and to enable easy ejection of the end closure 15 once it has been completely formed in apparatus 21, the concave edge portion 95 extends in an arc which has a radius 95R which is larger than the radius 92R of the central edge portion 92 by an amount roughly equal to twice the wall thickness of the blank 85. In this example of the invention the centers of radius lines 92R and 95R are .020 inch apart along line 100. In addition, it has been found that to closely control the frustoconical wall portion 17 comprising end closure 15 within narrow limits it is preferred that the inclined surfaces defined by substantially frustoconical surfaces 45 and 80 be arranged so that with the die 22 and punch 23' at their innermost position the normal distance between substantially frustoconical surfaces 45 and 80 is roughly 30% greater than the thickness of the blank 85 used to form the particular end closure 15.

In the exemplary apparatus 21 of this invention illustrated in the drawings the cooperating portions of such apparatus are constructed so that the frustoconical Wall portion 17, which is adapted to be inserted within an associated end portion of a can on which end closure 15 is to be used, preferably has an inclination of approximately 1330 in an outwardly diverging manner from the vertical. Accordingly, the angle of inclination of frustoconical surface 45 is approximately 1330 and the angle of inclination of frustoconical surface with respect to the vertical is also 1330. This particular arrangement assures provision of wall portion 17 to the desired controlled configuration. However, it will be appreciated that the cooperating surfaces may be arranged at other desired angles to provide drawn wall portion 17 which is substantially frustoconical.

Having described the detailed dimensional arrangement and relationship of the various surfaces comprising the die 22 and punch 23 the description will now proceed with a detailed description of the drawing operation utilized to form frustoconical wall 17. Thus, a peripheral annular strip portion of the blank is clamped and held between the rings 41 and 60 and as the punch 23 is moved to its innermost position toward the die 22 the action that takes place along the frustoconical surfaces 45 and 80 is a drawing action and such drawing action avoids compressive forces acting substantially transverse, i.e., substantially perpendicular to the inclined frustoconical surfaces 45 and 80'. The inclined frustoconical surfaces 45 and 80 in effect guide the drawn portion within narrow limits and this action together with configuration of edges 40 and 66 of rings 41 and 60 respectively assures the forming of an end closure 15 having a precisely controlled configuration, and which is particularly adapted to be mechanically handled using suitable equipment in a mass production operation.

To highlight the problem encountered using present equipment to form metal end closures, reference is now made to FIG. 6 of the drawings. The structure shown in FIG. 6 is similar in part to structure utilized to form end closure 15. For ease of presentation corresponding parts of the structure presented in FIG. 6 will be designated by the same general reference numeral as similar parts in FIG. 7 of the drawings followed by the letter designation A and not described again in detail, it being understood their function is generally the same as previously described and such corresponding parts are controlled and operated essentially as previously described. Those parts of the structure of FIG. 6 which are substantially different from corresponding parts of the apparatus 21 previously described in connection with FIG. 7 will be designated by a new reference numeral also followed by the letter designation A and described in detail.

Thus, it is seen that the clamping ring 41A has a right circular cylindrical inner surface portion 103A while the clamping ring 81A has a cooperating outer right circular cylindrical surface 104A. Upon urging the punch 23A and die 22A together essentially in the manner described and shown in FIG. 4 in connection with the die 22 and the punch 23, it will be seen that a portion of the metal blank used to define an end closure designated by the numeral 15A extends between surfaces 103A and 104A in an uncontrolled manner.

If the elastic limit of the material being used to form the particular end closure 15A has been exceeded it will be appreciated that its wall portion shown at 105A and designated by the numeral 17A to correspond to wall portion 17 of the end closure 15 will be defined substantially without too much deviation from one end closure to another. However, the normal forming operation-is such that the elastic limit of the particular material is generally not exceeded; therefore, by having an uncontrolled portion defined by the space indicated at 108A in FIG. 6 it will be appreciated that once the punch 23A is moved away from the die 22A there is a tendency for the metal to bounce back different amounts from one end closure to the next and it is virtually impossible with the type of apparatus shown in FIG. 6 to provide a plurality of substantially idential end closures which may be stacked and individually dispensed by mechanical equipment in an automatic manner without the likelihood of jamming the equipment.

In particular, as seen in FIG. 8 of the drawings wherein a vertical stack 107 of end closure 15A is shown, it will be seen that such stack is normally carried on a pair of cooperating horizontally extending coplanar arms each designated by the numeral 106 so that an entire stack 107 is carried essentially in a vertical manner. An associated pair of cooperating horizontally extending arms each designated by the numeral 110 and each having a substantially L-shaped finger 111 is also provided. Each arm 106 is adapted to be pivoted horizontally about an associated vertical shaft. Similarly, each arm 110 is adapted to be horizontally pivoted about an associated vertical shaft.

To release the lowermost end closure 15A arms 110 are pivoted into the position shown in FIG. 8 so that fingers 111 would normally engage diametrically opposite portions of the end closure 15A supported against the lowermost end closure. Subsequently arms 106 are pivoted away allowing the lowermost end closure to be dropped. However, because of the unpredictable dimensional configuration of the end closures 15A formed using present apparatus and methods it is entirely possible and often occurs that the end closures 15A are often badly shutfied and misaligned in stack 107. Thus, upon moving fingers 111 in position one finger 111 might be moved between the lowermost end closure and the adjoining end closure while the opposite finger 111 might be moved between the lower two end closures and the adjoining end closure arranged therea'bove as shown at 113. Upon swinging arms 106 away and subsequently moving them back in to a supporting relation the then lowermost end closure is hanging from one of its side edges and is generally struck by one of the arms 106 which is very undesirable because it causes delays and requires adjustment of the stack of end closures 15A and of the mechanical handling equipment.

By contrast, it will be seen that in FIG. 9 where the end closures 15 are formed in accordance with the apparatus and method of this invention the vertical stack thereof designated by the numeral 115 is arranged in an essentially unshufiled manner. Each time the arms 110 are horizontally pivoted into a supporting position the fingers 111 move between the lowermost end closure 15 and the adjoining one in the required manner enabling each end closure 15 to be efficiently dispensed from stack 115 once arms 106 are pivoted away as previously described. Upon moving arms 106 back into position the entire stack 115 is again supported by arms 106. Thus, it is seen that each end closure 15 made using the improved apparatus and method of this invention has a precisely controlled configuration and such end closures 15 are easily stacked in the manner shown at 115 and readily serially mechanically dispensed.

In providing end closures for metal cans of right circular cylindrical outline, for example, and of the type used to contain carbonated beverages it has been found that it is necessary to provide end closures having greater 'wall thicknesses for carbonated soft drinks than for beer, for example, which has less carbon dioxide content. Therefore, for soft drinks it is necessary to utilize sheet metal blanks which are thicker. The unique configuration and construction of the cooperating die 22 and punch 23 of this invention enables the forming of precisely controlled end closures having different wall thicknesses and capable of being used as end closures for either soft drink or beer cans without requiring modification of the particular apparatus 21 or of the method of forming.

Therefore, by providing the controlled configuration substantially frustoconical surfaces 45 and 80 in essentially the ratios described it will be appreciated that frustroconical portion 17 of end closure 15 may be formed in a controlled manner and irrespective of whether the ultimate tensile strength of the particular metal being aluminum sheet strip having a thickness of .0154 inch has been successfully utilized. However, as indicated previously the improved apparatus and method of this invention may be utilized to form end closures for both beer cans and soft drink cans which require different thicknesses. For example, sheet metal blanks having Wall thicknesses ranging from .0131 to .0162 have been successfully used to make precisely controlled end closures without requiring a die change in the forming apparatus.

By way of illustration, some typical dimensions for an exemplary end closure made of aluminum will now be described and presented in connection with FIG. 7 of the drawings. However, it is to be understood that such dimensions are applicable to only one exemplary end closure and may be changed as desired. Thus, as seen in FIG. 7, the overall diameter of an exemplary end closure 15 is 3.021 inches, and the overall height is .257 inch plus the thickness of the particular metal used to form the end closure.

With the die 22 and the punch 23 urged together it will be noted that the substantially frustoconical surface 45 has its lowermost position arranged on a 2.473 inches diameter While the uppermost position of frustoconical surface 45 is arranged on a 2.5866 inches diameter. The space between frustoconical surfaces 45 and is .0154, which is the nominal wall thickness of the exemplary blank illustrated, plus .0054 inch which is roughly equal to the wall thickness plus 30% of such wall thickness.

In addition, in this example of the invention the radius 92R of convex edge means 92 is .219 inch while the radius 95R of concave edge means 95 is .2554 inch and that the centers of such radii are arranged on straight line 100, as previously mentioned, which lies immediately adjacent a right circular cylindical surface which essentially bisects the ring 41. It will be noted from the dimensions illustrated in FIG. 7 that the innermost position of surface 45 provided on ring 41 has a diameter of 2.473 inches while the outer diameter of such ring is 2.987 inches with line being at the 2.774 inches diameter.

While present preferred embodiments of this invention, and methods of practicing the same, have been illustrated and described, it will be recognized that this invention may be otherwise variously embodied and practiced by those skilled in the art.

What is claimed is:

1. An apparatus for making a metal end closure for a can comprising, a die having a first ring provided with a convex outer edge and a first inclined surface adjoining and extending inwardly from said convex outer edge, and a. punch having a second ring and a second inclined surface corresponding in configuration to said first inclined surface, said first and second rings being adapted to engage and hold a peripheral annular strip of a sheet metal blank, said first and second inclined surfaces cooperating to enable drawing of a portion of said blank therebetween in a controlled manner upon moving said die and punch together, and with said die and punch moved together to their innermost position a controlled roughly tubular volume is defined between said inclined surfaces having a thickness defined by the perpendicular distance between said inclined surfaces which is greater than the thickness of said blank, said greater thickness of said tubular volume at said innermost position assuring at least one of said inclined surfaces is spaced from said portion as viewed on any particular plane arranged substantially transverse said inclined surfaces so that compressive forces acting against said portion in a direction substantially transverse said inclined surfaces are avoided to thereby assure the forming of said end closure having said portion formed to a precisely controlled tubular configuration.

2. An apparatus as set forth in claim 1 for making an end closure for a substantially cylindrical can in which said first and second inclined surfaces comprises cooperating first and second frustoconical surfaces respectively which are arranged about a common axis and cooperate to define said tubular volume as a substantially frustoconical volume and said portion as a corresponding substantially frustonconical portion, said thickness of said frustoconical volume being roughtly 30 percent greater than the thickness of said blank, and said frustoconical surfaces confining said frustoconcial portion over its en tire height and thus assure the provision of said precisely controlled configuration.

3. An apparatus for making a metal end closure for a substantially cylindrical can comprising, a die having a first ring provided with a convex outer edge and a first frustoconical surface adjoining and extending inwardly from said convex outer edge, and a punch having a second ring and a second frustoconical surface corresponding in configuration to said first frustoconical surface, said first and second rings being adapted to engage and hold a peripheral strip of a sheet metal blank, said first and second frustoconical surfaces cooperating to draw a portion of said blank therebetween in a controlled manner upon moving said die and punch together, and with said die and punch moved together to their innermost position a controlled roughly tubular volume is defined between said frustoconical surfaces having a thickness defined by the perpendicular distance between said frustoconical surfaces which is greater than the thickness of said blank, said tubular volume assuring compressive forces acting against said portion in a direction substantially transverse said frustoconical surfaces are avoided to thereby assure the forming of said end closure having said portion formed to a precisely controlled tubular configuration, said first and second frustoconical surfaces being arranged about a common axis and cooperating to define said tubular volume as a substantially frustoconical volume and said portion as a corresponding substantially frustoconical portion, said thickness of said frustoconical volume being roughly 30 percent greater than the thickness of said blank with said frustoconical surfaces confining said frustoconical portion over its entire height and thus assuring the provision of said precisely controlled configuration, said punch comprising a knockout ring having a concave outer edge corresponding in configuration to said convex outer edge of said first ring and aligned thereabove, said concave outer edge being adapted to shape an annular part of said blank which adjoins said strip against said convex outer edge after drawing of said portion to provide said end closure with a more accurate final configuration which also assures easier knockout thereof.

4. An apparatus as set forth in claim 3 in which said convex outer edge of said first ring comprises a central circular portion adjoined on opposite ends thereof by oppositely arranged outer and inner circular portions each having a substantially smaller radius than said central circular portion, and said concave outer edge of said knockout ring comprises a concave circular portion which has a larger radius than said central circular portion, said circular portions cooperating to assure said annular part is formed in a smooth substantially unstressed manner and with an overall substantially arcuate configuration which further assures said easier knockout.

5. An apparatus as set forth in claim 4 in which said central circular portion and said concave circular portion each has its center arranged on a straight line positioned immediately adjacent to and parallel with a right circular cylindrical surface of revolution bisecting said first ring.

6. An apparatus as set forth in claim 4 further comprising, a blanking member fixed in said die and having a first cutting edge of circular outline and said second ring having a second cutting edge defining its outer edge which corresponds in circular outline to said first cutting edge and having an inner circular edge, said first and second cutting edges cooperating to cut said metal blank having a circular outline and said inner and outer circular edges of said second ring defining a bearing surface therebetween, and a third ring in said die supported concentrically around said first ring in an axially outwardly resilient manner, said third ring being supported for telescoping movement within said die, and upon relatively moving said die and punch together said bearing surface of said second ring urges said annular strip of said blank against said third ring to telescope said third ring inwardly causing said inner edgeof said second ring to form said annular strip around said outer circular portion of said first ring to simultaneously hold said blank and define a controlled configuration circumferential lip on said end closure.

7. An apparatus as set forth in claim 4 in which said larger radius of said concave circular portion is larger than said central circular portion by an amount roughly equal to twice the thickness of said blank.

8. A method of making a metal end closure for a can comprising the steps of holding a peripheral annular strip of a sheet metal blank between a first ring of a die and a second ring of a punch and drawing a portion of said blank which adjoins said annular strip between cooperating first and second inclined surfaces of said die and punch respectively, said drawing being performed in a controlled manner upon moving said die and punch together, and with said die and punch moved together to their innermost position a controlled roughly tubular volume is defined between said inclined surfaces having a thickness defined by the perpendicular distance between said inclined surfaces which is greater than the thickness of said blank, said greater thickness of said tubular volume at said innermost position assuring at least one of said inclined surface is spaced from said portion as viewed on any particular plane arranged substantially transverse said inclined surfaces so that compressive forces acting against said portion in a direction substantially transverse said inclined surfaces are avoided to thereby assure the forming of said end closure having said portion formed to a precisely controlled tubular configuration.

9. A method as set forth in claim 8 in which said drawing step comprises drawing said portion of said blank between cooperating first and second frustoconical surfaces which define said first and second inclined surfaces respectively, said first and second frustoconical surfaces are arranged about a common axis and cooperate to define said tubular volume as a substantially frustoconical volume and said portion as a substantially frustoconical portion, said thickness of said frustoconical volume being roughly 30 percent greater than the thickness of said blank, and said frustoconical surfaces confining said frustoconical portion over its entire height and thus assure the provision of said precisely controlled configuration.

10. A method of making a metal end closure for a can comprising the steps of holding a peripheral annular strip of a sheet metal bank between a first ring of a die and a second ring of a punch and drawing a portion of said blank which adjoins said annular strip between cooperating first and second frustoconical surfaces of said die and punch respectively, said drawing being performed in a controlled manner upon moving said die and punch together, and with said die and punch moved together to their innermost position a controlled roughly tubular volume is defined between said frustoconical surfaces having a thickness defined by the perpendicular distance between said frustoconical surfaces which is greater than the thickness of said blank, said tubular volume assuring compressive forces acting against said portion in a direc- 11 tion substantially transverse said frustoconical surfaces are avoided to thereby assure the forming of said end closure having said portion formed to a precisely controlled tubular configuration,said first and second frustoconical surfaces being arranged about a common axis and cooperating during said drawing step to define said tubular volume as a substantially frustoconical volume and said portion as a substantially frustoconical portion, said thickness of said frustoconical volume being roughly 30 percent greater than the thickness of said blank with said frustoconical surfaces confining said frustoconical portion over its entire height and thus assuring the provision of said precisely controlled configuration, said first ring having a convex outer edge including a central circular portion and said first frustoconical surface adjoins and extends inwardly from said convex outer edge, ,and comprising the further step of shaping an annular part of said blank which adjoins said strip againstrsaid convex edge with a knockout ring in said punch which has a concave outer edge corresponding to said convex outer edge,

said concave outer edge having a concave circular portion which has a larger'radius than said central circular portion, said shaping step being achievedapproximately at the end of said drawing step to also define a precisely controlled chime end for said end closure.

11. A method as set forth in claim 10 comprising the further step of positioning said die and punch soithat said concave circular portion and said central circular portion are arranged with their centers on a straight line right circular cylindrical surface of revolution bisecting said first ring to assure said drawing and shaping steps are achieved in a precise manner.

12. A method as set forth in claim 9 further comprising the preparation step of cutting saidblank from a sheet of metal stock with cooperating cutting edges provided in said die and punch to define said sheet metal blank having a circular peripheral outline.

13. A method as set forth in claim 9 in which said holding step comprises holding said annular strip of a disc-like sheet metal blank having a circular peripheral outline and made of metal containing aluminum.

References Cited UNITED STATES PATENTS 1,724,117 8/1929 Unke 72-350 1,826,659 10/1931 Meier 113-121 1,919,287 7/1933 Auble 72-349 2,225,710 12/ 1940 Norris 72-354 2,434,375 1/ 1948 Van Saun 113-121 2,763,228 9/1956 Lawson 72-354 3,302,441 2/1967 Bozek 113-120 3,372,569 3/1968 Bozek 72-349 5 3,163,142 12/ 1964 Buhrke 72-344 CHARLES W. LANHAM, Primary Examiner E. M. COMBS, Assistant Examiner US. Cl. X.R.

positioned immediately adjacent to and parallel with a 3 72-345, 352

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