US2750910A - Apparatus for producing crown closure - Google Patents

Description

June 19, 1956 G, HAMMOND, JR 2,750,910

APPARATUS FOR PRODUCING CROWN CLOSURE Filed Feb. 18, 195o 2 sheets-sheet 1 GEORGE HAMMOND JR ,3m a. Mn

June 19, 1956 G, HAMMOND, JR

APPARATUS FCR PRODUCING CROWN CLOSURE 2 Sheets-Sheet 2 Filed Feb. 18. 1950 3 vw cam/tofu GEORGE HAMMOND JR- abby/tu APPARATUS FOR PRODUCING CRWN CLSURE George Hammond, Jr., Manheim Township, Lancaster County, Pa., assigner to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Application February 18, 1950, Serial No. 145,010

2 Claims. (Cl. 113-42) This invention relates to crown closures and their manufacture and more particularly to a method and apparatus for producing closures of this type on double-action presses.

This application is a continuation-in-part of my copending application, Serial No. 65,825, filed December 17, 1948, now abandoned, which is a continuation-in-part of application Serial No. 18,013, filed March 30, 1948, now abandoned.

In the production of crowns on a double-action press, a metal blank is cut from sheet stock on the closing action of the press. This cut blank is held momentarily between the two die assemblies, after which it is formed to the proper configuration by the action of a forming ram which travels down through the movable die assembly and forms the cut blank over the forming die. This forming operation is accomplished on the second action of the press. The cutting die is actuated by a cam mechanism which is so designed as to provide a dwell at the bottom of the stroke to hold the female die member in its lowermost position during the forming operation. The forming ram is actuated by a crank which imparts reciprocating motion to the ram head. It will be understood, of course, that the crank may be replaced by an eccentric or other means to impart reciprocating motion to the ram. Single-action presses have been used to a minor extent in the production of crown closures. In a press of this type the cutting punch and forming die are positioned in the top or movable part of the press and the blanking and forming operation is carried out on a single stroke of the press. On the downward or closing action of the press, the cutting punch shears a metal blank from the sheet stock placed over the female die member. This cutting punch and forming die continue their downward path of travel and bend the metal blank down over a stationary forming head affixed to the bottom platen of the press. In a single-action press, the cut-out blank is held between the cutting and forming die combination and a drawing ring which surrounds the stationary forming head. This drawing ring is urged downwardly by the cutting punch and forming die against-a spring, rubber cushion, or other resilient means disposed in the lower portion of the press assembly. v

It will be clear to those skilled in the art of metal cutting and forming that the double-action press has many advantages over a single-action press. One chief advantage is derived from the short stroke requiredv in the double-action press. Inasmuchas the cutting and forming operations are carried out separately, the power re'- quired for each operation is less than is required for the combined operation on a single-action press. It is, therelfore-possible to accomplish this work by a shorter stroke of the press; and consequently, the equipment can be operated at a faster rate than a single-action press.

wniteci States Patent 'i Patented June 19, 1956 ice Another advantage is derived from the accurate adjustment on the cutting and forming tools which can be attained and maintained on a double-action press inasmuch as the tools are all adjusted by positive means. On a single-action press, the drawing ring is working against a spring, rubber cushion, or other resilient means which have a tendency to become fatigued during continual use of the press; and therefore, close adjustment of the drawing ring cannot be maintained. The above are some of the chief reasons why it has been common practice in the closure industry to produce crown closures on doubleaction presses.

In most cases, the crown blanks are cut from tin plate which has been previously lithographed with a suitable decoration. The design of the double-action presses currently used in the production of crown closures is such that the tin plate is necessarily placed in the press with the lithographed or exterior surface down in engagement with the stationary die assembly located in the bottom platen of the press. The cutting of the blank is accomplished by shearing of the metal between the inner circumference of the female die member and the outer circumference of the male die member as the dies are brought together. In a shearing action of this kind, the die having the larger cutting diameter, which is the female die member, bends the metal away from the inner circumference of the die and curls the metal around the die member having the smaller cutting diameter. This curling action forms a finished blank having a rounded edge on the side which has been cut by the female die member.

In crown forming tools used prior to this invention for producing crowns on double-action presses, the circular die having the larger cutting diameter engaged the decorated or exterior surface of the tin plate and, consequently, formed a rounded edge on the exterior or decorated side of the blank.

The purpose of this invention is to provide a method and apparatus for producing crowns having a rounded edge on the bottom surface. One of the chief advantages to be derived from a crown having the bottom edge rounded is that it will flow more freely in the chutes of bottle-capping equipment and also in the crown assembly equipment.

It has also been found that crowns having a rounded edge on the bottom surface do not scratch and mar the decorated surface of other crowns when they are packaged for shipment or storage. Due to the configuration of crown closures, they have a tendency to nest when packaged. With the rounded edge provided on thesev new crowns, the possibility of scratches to the decoration resulting from this nesting is negligible.

To achieve the desired results described above, I have developed'sheet metal cutting tools adapted for use in the conventional double-action presses common to the closure industry in which the die having the greater cutting diameter contacts the interior or undecorated surface of the crown blank and, therefore, rounds the edge of the interior surface of the crown rather than the edge of the exterior surface.l

' In order that my invention maybe more readily understood, the same will be described in connection with the attached drawings in which:

Figure 1 is a cross-sectional view of a press assembly .showing the tools in position inv an open press;

'.Figure 2 `is a cross-sectional view similar to Figure l showingthe press closed with'a cut blank positioned between the two sets of dies; .-.I Figure 3 is va cross-sectional view similar to Figure l showing thezp'ress closed `with a in' the die assembly;

formed crown in position' Figure 4 is an isometric view of the cutting punch and forming die assembly of my invention;

Figure 5 is an isometric view of the forming die;

Figure 6 is a cross-sectional view showing the position of the forming die within the male cutting punch;

Figure 7 is an enlarged cross-sectional view of a portion of a finished crown closure; and

Figure S is an enlarged cross-sectional view of a portion of a cut blank.

Referring to Figures l, 2, and 3, there is shown a male die assembly 2 and a female die assembly 3. The male die assembly 2 comprises a cutting punch 4, a crown forming and crimping die 5, and an ejector assembly 6, said ejector assembly comprising an ejector sleeve 7 and an ejector 8. The forming and crimping die 5 rests on the top surface of an adjusting sleeve 9 and is secured thereto by means of a split collar il which tits on a ri-ange E?. on the bottom of the forming and crimping die 5 and flange i3 on the top of adjusting sleeve 9 which is in threaded engagement with the die shoe 10. This collar 11 permits movement of the forming and crimping die 5 in a direction parallel to the direction of travel of the press head but it does not prevent the forming and crimping die 5 from rotating or moving slightly in a direction perpendicular to the direction of travel of the press head. The reason for this movement will be explained more fully hereinafter. The circular cutting punch 4 surrounds forming and crimping die 5 and rests on shoulder 1d of the die shoe lo. A stripper plate 15 is provided surrounding the cutting punch 4, but is not in engagement therewith. The purpose of this stripper plate 15 is to remove the skeleton, from which the blanks have been cut, from its engagement with the center surface of the cutting punch 4.

The female die assembly 3 is made up of die member 16 which is adapted to cooperate with the cutting punch 4 to shear the blank. The female die member 16, after it has sheared the blank, overlaps and surrounds the cutting edge of the cutting punch 4 while the crown is being formed to final configuration. Positioned within this female die member 16 is a holding sleeve 17, the upper portion of which tits snugly into the female die member i6; however, the lover portion of the outer surface thereof is cut out, leaving an opening 18 between the holding sleeve i7 and the female die member 16. This opening is preferably about .030" in width and extends about .75 along the side of the holding sleeve 17. The purpose of this opening is to collect dirt and excess lacquer removed from the tin plate, thus preventing an accumulation of the same at the lower surface of the holding sleeve 17. This opening is automatically cleaned by the constant running of the machine jarring the material loose. This holding sleeve 17 does not extend down as far as the bottom of the female die member lo, leaving a small recess 19 which is approximately the same diameter as the blank to be cut from the tin plate. This recess is slightly deeper than the thickness of theblank to be cut so that the blank will not be lirmly clamped between the male and female die members. The holding sleeve 17 is locked in place in the female die member f6 by means of a locking pin 2t) which tits into companion grooves in the female die member i6 and the holding sleeve 17. This locking pin 20 serves only to hold the holding sleeves in place but is not the sole means for preventing the upward movement of the hilding sleeve, such upward movement being prevented by the shoulder 21 of the female die member which engages the top surface of the holding sleeve. The holding sleeve i7 is free to rotate with respect to the female die member i6.

Operating within the holding sleeve 17 is a forming ram 22 which moves downwardly, and in cooperation with forming and crimping die, shapes the crown to its nal configuration.

On the closing or cutting action of the press, the male die assembly 2 remains stationary and the female die assembly is moved into engagement therewith, so that the sheet metal positioned between the two assemblies is sheared by the cutting edge 23 of the male cutting punch 4 and the cutting edge 24 of the female die member 16. The clearance between these two cutting edges should be such that proper shearing action is obtained.

Figure 2 of the drawing shows the die in closed posi tion with the cut blank 25 in position between the two die assemblies. The skeleton from which the blank 25 has been cut is shown at 26. The arrangement of parts illustrated in Figure 2 shows the position of the various elements of the assembly at the completion of the first action of the double-action press.

Figure 3 shows the position of the elements after the completion of the second action ofthe double-action press. It will be noted from the examination of Figure 3 that the forming ram 22 has been forced downwardly against the blank 25 and has forced the blank down over the forming die 5, thus forming it to the desired configuration. The ejector sleeve 7 and the ejector 8 are forced down by the action of the forming ram 22. The ejector sleeve 7 compresses a spring in the bottom of the press assembly, not shown, and the ejector 8 compresses spring 27 in the center of the ejector sleeve 7. Upon the withdrawal of the forming ram 22, the ejector sleeve 7 and the ejector 8 are returned to their original position as shown in Figure 1.

To insure the proper formation of the crown, it is essential that the relative position of the forming die 5 with respect to the cutting punch 4 be properly adjusted. In assembling the component parts of the die assembly, the male cutting punch 4 is press fitted into the die shoe 10 and held firmly therein by means of a set screw not shown. The forming die 5 is then placed inside the cutting die 4 and its height is properly adjusted by means of adjusting sleeve 9 which is in threaded engagement with the die shoe l0.

For best results it has been found desirable to adjust the forming die 5 so that its highest portion is about .030 above the top surface of the cutting punch 4. With an adjustment of this kind, the downward movement of the female die member will tend to iiex the metal blank 25 slightly downward around its perimeter. When the downward movement of the female assembly 3 stops, the blank is held between the holding sleeve ll7 and the forming die 5, but not between the holding sleeve 17 and the top surface of the cutting punch 4. Since the forming die 5 has a relatively small top surface area for engagement with the under or decorated surface of the blank 25, the possibility of marring the decoration during the forming operation is slight. Also the limited area of clamping between the holding sleeve 17 and the forming die 5 is sufiicient to hold the blank 25 in the proper position for the forming operation but insuiicient to prevent slippage so that the blank can be actually formed by bending rather than drawing.

As another precaution to prevent marring and scratch ing of the decoration, the top surface of the cutting punch 4 and the forming die 5 have been specifically designed. The design of these two elements is shown in Figures 4, 5, and 6. From an observation of these figures, it will be apparent that the inner circumference of the top edge of the male cutting punch 4 is rounded and also the outer circumference of the top edge of the forming die 5 is rounded to eliminate sharp edges in the area over which the metal moves. The rounded edge of the cutting punch 4 is designated by the numeral 28, and the rounded edge on the forming die 5 is shown at 29. These rounded edges are clearly shown in Figure 6. The rounded edge 2S on the cutting punch 4 permits the metal which is forced through the grooves 30 on the forming die 5 to start its downward path of travel before the outer rim of the blank actually reaches the grooves 30 of the forming die 5. -The metal which is formed over the projections 31 of the forming die continues to move in a substantially horizontal direction regardless of the rounded edges 28 and 29.

In the preferred embodiment, the cutting punch 4and the forming and crimping die 5 are made as separate units so that the cutting punch can be removed from the assembly for sharpening without the necessity of grinding the surface of the forming and crimping die 5 and so that the forming die 5 can be properly positioned with respect to the cutting die 4.

For most satisfactory operation, the outside diameter of the forming die 5 should be about .015 less than the inside diameter of the cutting punch 4. This clearance permits the forming die 5 to move slightly in a lateral direction to facilitate the forming ram 22, centering itself in the forming die 5. This movement is necessary in gang set-ups of the type commonly used in the manufacture of crown closures, because through constant usage there is a tendency for the forming ram and forming die to get out of alignment. This oating movement of the forming die 5 permits the die to move slightly and properly align itself with the forming ram. This materially aids in the producing of a more uniformly formed crown, as it overcomes the possibility of the ram exerting more pressure on one side of the blank than on the other.

Because of this floating action, it is desirable to make the wall thickness of the forming die 5 greater than the wall thickness of the cutting punch 4, because the lateral stress caused by the forming ram 22 entering the forming die 5 must be withstood by the forming die 5.

In designing the tools for use in carrying out my invention, it is essential that the top surfaces of the forming die 5 and the bottom surface of the holding sleeve 17 be normal to the longitudinal axis of the die assembly. This is necessary so that the cut-out blank 25 will be held by a uniform pressure around its circumference. If desired, the bottom edge of the female cutting die 16 can be ground to a slight taper so that the circumference of the blank is sheared progressively rather than instantaneously.

Figure 7 shows a cross section of a portion of the fmished crown showing the rounded edge 34 on the interior of the crown.

Referring to Figure 8, there is shown to exaggerated scale a cut blank 25 having a film of decorating paint 33 applied thereto. This View shows the rounded edge 34 which is on the side of the blank opposite the side to which the decorating paint has been applied.

In the operation of the device of my invention, a sheet of suitable metal such as tin plate having a decoration applied to one side thereof is placed on the stripper plate 15 with the decorated surface down. The female die assembly 3 which is in alignment with the male die assembly Z moves downwardly and the blank is sheared by the cutting edge 23 of the male die member 4 and the cutting edge 24 of the female die member 16. The female die member continues its downward movement for a short distance and overlaps the male die member, completely surrounding the cutting edge thereof as shown in Figure 2. At this phase of the operation, the cut blank is held between the bottom edge of the holding ring 17 and the top surface of the forming die 5. Immediately after the blank has been cut, the forming ram 22 contacts the undecorated surface of the blank and, in cooperation with the forming and crimping die 5, forms the blank to the desired configuration. During this forming operation, the holding sleeve prevents the edge of the metal blank from bending upwardly. Since the edge cannot bend upwardly, the downward action of the ram 22 forces the metal over the serrations of the forming `and crimping die and forms the closure to the desired configuration.

After the completion of the forming operation, the fe male die member moves upwardly away from the male die member and the formed crown is ejected from the forming and crimping die 5 by the ejector rod 8. The skeleton from which the blank has been cut is then removed from the male die member by means of the stripper plate 15 which is actuated by means not shown.

It will be clear from the foregoing description that I have developed a method and apparatus for producing crown closures in which the bottom edge of the finished crown will be rounded by the action of the female cutting die member which shears the blank. The tools covered by this application are adapted to fit the conventional double-action press currently used in the productiorrof crown closures in the industry. It is not necessaryl to change the pressV mechanism, and the conventional tools may be reinserted in the press without necessitating any alterations.

I claim:

1. In a die set for shearing and forming crown closure shells and similar articles from sheet material in a doubleacting press, the combination of a hollow punch; a hollow forming member disposed within said punch having a forming surface on the inner periphery thereof, said hol low punch being provided with an external severing edge on the outer periphery thereof and a rounded edge in the inner periphery adjacent the outer edge of said forming member, the position of said forming member with respect to said punch being such that the top surface of the forming member terminates in a plane above the top surface of said punch; a hollow die having an internal severing edge on the inner periphery complementary to the severing edge of said punch when said punch is disposed within the said die to sever a blank from a sheet of material disposed between the punch and die upon the closing action of said press, with the outer periphery of the blank having a slightly curved surface extending toward the severing edge of the punch; a hollow clamping member disposed within said die and secured thereto; a clamping surface on said clamping member complementary to the top surface of said hollow forming member for slip-gripping the blank therebetween when the press is closed; and a forming ram, said ram being disposed within said clamping member and being movable with respect thereto to a position below said clamping member and within the said hollow forming member to engage a limited area of said blank on the side opposite the side engaged by the forming member to bend the same over said forming surface to form an article of the desired configuration upon the second action of said press, the outer diameter of the forming die being less than the inner diameter of the hollow punch to permit the forming die to center itself with respect to the forming ram.

2. In a die set for shearing and forming crown closure shells and similar articles from sheet material in a doubleacting press, the combination of a hollow punch; a hollow forming member disposed within said punch having a forming surface on the inner periphery, the outer diameter of said forming member being substantially the same as the inner diameter of the punch, said hollow punch being provided with an external severing edge on the outer periphery thereof and a rounded edge on the inner periphery adjacent the outer edge of said forming member, the position of said forming member with respect to said punch being such that the top surface of the forming member terminates in a plane above the top surface of said punch; a hollow die having an internal severing edge on the inner periphery complementary to the severing edge of said punch when said punch is disposed within said die to sever a blank from a sheet of material disposed between the punch and die upon the closing action of said press, with the outer periphery of the blank having a slightly curved surface extending toward the severing edge of the punch; a hollow clamping member disposed within said die and secured thereto; a clamping surface on said clamping member complementary to the top surface of said hollow forming member for slip gripping the blank therebetween when the press is closed; and a forming ram, said ram being disposed within said clamping member and being movable with respect thereto to a position below said clamping member and within the said hollow forming member to engage a limited area of said blank on the side opposite the side engaged by the forming member to bend the same over said forming surface to form an article of the desired configuration upon the second action of said press.

References Cited in the le of this patent UNITED STATES PATENTS Opsal Mar. 2, 1909 8 Adriance etal June 11, 1912 Elsner July 2, 1918 Bohle Oct. 16, 1923 Carter Dec. 19, 1933 Ho'thcrsall Apr, 6, 1937 MacCokrdy Apr. 13, 1937 Plumb Oct. 24, 1939 Wareham Aug. 5, 1941

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