Thread Forming Apparatus And Associated Method

This application is a non-provisional application of and claims priority to U.S. Patent Provisional Application Ser. No. 63/644,080, filed May 8, 2024, titled, “Thread Forming Apparatus And Associated Method.”

The disclosed concept relates generally to thread forming apparatus for forming thread members and, more particularly to thread forming apparatus for forming thread members in beverage cans. The disclosed concept further relates to methods of forming thread members in beverage cans.

Metallic beverage containers are sealed by closures disposed on/over openings in order to protect the contents contained therein from being exposed to air, moisture or other environmental elements and prolong the shelf-life of the contents. Most metallic beverage containers are not resealable meaning once they are opened, they cannot be closed or resealed. Metallic beverage containers usually include “pull tabs” structured to be grabbed by the consumers via a ring and pulled to remove the top of the beverage container or “stay on tabs” to break open a perforated opening of the beverage container. These types of closures are common in metallic beverage containers, but once opened cannot be closed or resealed. Such lack of resealability results in inconvenience to the consumers who must intake the contents quickly upon opening before the contents lose carbonation, spoil, or oxidize. Few metallic beverage containers contain threaded closures that can be reclosed or resealed. However, creating such threaded closures is challenging. One challenge is that it is difficult to create threads in a can body due to the thinness of aluminum used in the can body. Such threads risk compromising the strength of the can body. Further it is challenging to create threads in a can body in a manner that is cost effective and conducive to high speed manufacture. Current resealable metallic beverage containers have not sufficiently met these challenges.

Hence, there is room for improvement in thread forming devices for metallic beverage containers. There is also a need for thread forming devices with high throughput for resealable beverage containers.

These needs, and others, are addressed by embodiments of the disclosed concept. In one example embodiment, a thread forming apparatus for use in forming a plurality of threads on a can body having a base and sidewall extending from the base is provided. The thread forming apparatus comprises: a punch mechanism including a punch shaft and a cylindrical punch coupled to the punch shaft and having a plurality of circumferentially spaced-apart punch projections, the punch mechanism being structured to be moved radially and rotate continuously about the rotation axis of the punch mechanism in a first direction; a die mechanism including a die shaft and a cylindrical die connected to the die shaft and having a plurality of circumferentially spaced-apart die recesses, the die mechanism being structured to be moved radially and rotate continuously about the rotation axis of the die mechanism in a second direction opposite the first direction; and a number of actuating arrangements connected to the punch shaft and the die shaft and structured to translate the punch mechanism and the die mechanism radially relative to a central axis of the can body and rotate each of the punch mechanism and the die mechanism about respective rotation axes for forming a plurality of threads on the can body.

Each punch projection may comprise a male thread form geometry and comprises a protrusion, a protuberance, or a ledge, and each die recess may comprise a female thread form geometry that is a negative of the male thread form geometry. The cylindrical punch may be positioned and structured to engage an outer surface of the sidewall of the can body and the cylindrical die may be positioned and structured to engage an inner surface of the sidewall of the can body. The cylindrical punch may be positioned and structured to engage an inner surface of the sidewall of the can body and the cylindrical die may be positioned and structured to engage an outer surface of the sidewall of the can body.

Another example embodiment provides for a thread forming apparatus for a can body having a base and a sidewall extending axially from the base. The thread forming apparatus includes a punch mechanism including a punch shaft and a convex shaped punch connected to the punch shaft, the punch mechanism being structured to be moved radially; a die mechanism including a die shaft and a cylindrical die connected to the die shaft and having a concave base, the die mechanism being structured to be moved radially; and an actuator connected to the punch shaft and the die shaft and structured to move axially the punch mechanism and the die mechanism relative to a central axis of a can body for forming a plurality of threads on the can body.

These and other objects, features, and characteristics of the disclosed concept, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economics of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are provided for the purpose of illustration and description only and are not intended as a definition of the limits of the disclosed concept.

Directional phrases used herein, such as, for example, clockwise, counterclockwise, left, right, top, bottom, upwards, downwards and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.

As used herein, the singular form of “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

As used herein, “structured to [verb]” means that the identified element or assembly has a structure that is shaped, sized, disposed, coupled and/or configured to perform the identified verb. For example, a member that is “structured to move” is movably coupled to another element and includes elements that cause the member to move or the member is otherwise configured to move in response to other elements or assemblies. As such, as used herein, “structured to [verb]” recites structure and not function. Further, as used herein, “structured to [verb]” means that the identified element or assembly is intended to, and is designed to, perform the identified verb. Thus, an element that is merely capable of performing the identified verb but which is not intended to, and is not designed to, perform the identified verb is not “structured to [verb].”

As used herein, “associated” means that the elements are part of the same assembly and/or operate together or act upon/with each other in some manner. For example, an automobile has four tires and four hub caps. While all the elements are coupled as part of the automobile, it is understood that each hubcap is “associated” with a specific tire.

As used herein, the statement that two or more parts or components are “coupled” shall mean that the parts are joined or operate together either directly or indirectly, i.e., through one or more intermediate parts or components, so long as a link occurs. As used herein, “directly coupled” means that two elements are directly in contact with each other. As used herein, “fixedly coupled” or “fixed” means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other. As used herein, “adjustably fixed” means that two components are coupled so as to move as one while maintaining a constant general orientation or position relative to each other while being able to move in a limited range or about a single axis. For example, a doorknob is “adjustably fixed” to a door in that the doorknob is rotatable, but generally the doorknob remains in a single position relative to the door. Further, a cartridge (nib and ink reservoir) in a retractable pen is “adjustably fixed” relative to the housing in that the cartridge moves between a retracted and extended position, but generally maintains its orientation relative to the housing. Accordingly, when two elements are coupled, all portions of those elements are coupled. A description, however, of a specific portion of a first element being coupled to a second element, e.g., an axle first end being coupled to a first wheel, means that the specific portion of the first element is disposed closer to the second element than the other portions thereof. Further, an object resting on another object held in place only by gravity is not “coupled” to the lower object unless the upper object is otherwise maintained substantially in place. That is, for example, a book on a table is not coupled thereto, but a book glued to a table is coupled thereto.

As used herein, the statement that two or more parts or components “engage” one another means that the elements exert a force or bias against one another either directly or through one or more intermediate elements or components. Further, as used herein with regard to moving parts, a moving part may “engage” another element during the motion from one position to another and/or may “engage” another element once in the described position. Thus, it is understood that the statements, “when element A moves to element A first position, element A engages element B,” and “when element A is in element A first position, element A engages element B” are equivalent statements and mean that element A either engages element B while moving to element A first position and/or element A either engages element B while in element A first position.

As used herein, “correspond” indicates that two structural components are sized and shaped to be similar to each other and may be coupled with a minimum amount of friction. Thus, an opening which “corresponds” to a member is sized slightly larger than the member so that the member may pass through the opening with a minimum amount of friction. This definition is modified if the two components are to fit “snugly” together. In that situation, the difference between the size of the components is even smaller whereby the amount of friction increases. If the element defining the opening and/or the component inserted into the opening are made from a deformable or compressible material, the opening may even be slightly smaller than the component being inserted into the opening. With regard to surfaces, shapes, and lines, two, or more, “corresponding” surfaces, shapes, or lines have generally the same size, shape, and contours.

As used herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality). That is, for example, the phrase “a number of elements” means one element or a plurality of elements. It is specifically noted that the term “a ‘number’ of [X]” includes a single [X].

As used herein, “about” in a phrase such as “disposed about [an element, point or axis]” or “extend about [an element, point or axis]” or “[X] degrees about an [an element, point or axis],” means encircle, extend around, or measured around. When used in reference to a measurement or in a similar manner, “about” means “approximately,” i.e., in an approximate range relevant to the measurement as would be understood by one of ordinary skill in the art.

As used herein, an “elongated” element inherently includes a longitudinal axis and/or longitudinal line extending in the direction of the elongation.

As used herein, “generally” means “in a general manner” relevant to the term being modified as would be understood by one of ordinary skill in the art.

As used herein, “substantially” means “for the most part” relevant to the term being modified as would be understood by one of ordinary skill in the art.

As used herein, “at” means on and/or near relevant to the term being modified as would be understood by one of ordinary skill in the art.

As the need for a resealable cans increases, metallic beverage containers (e.g., without limitation, cans) with threaded closures that can be used to reseal the containers have been developed. However, the thread forming devices for the containers with the external threads are expensive and not conducive to high-speed manufacture. Example embodiments of thread forming apparatus in accordance with the disclosed concept achieve radial motion of a punch and a die to place threads (e.g., recesses, indentations, or other thread forms) at a plurality of points along the circumference of cans (or other suitable containers) at a very high speed, resulting in a high-throughput manufacturing of the threaded, reusable metallic beverage containers, the high-throughput being substantially higher than the throughput by the existing thread forming devices for metallic beverage containers. As such, example thread forming apparatus in accordance with the disclosed concept resolve the manufacturing inefficiencies and high costs associated with existing thread forming devices for metallic beverage containers. Further, due to their capability to produce a high-throughput at a high-speed, the example thread forming apparatus in accordance with the disclosed concept can be easily included in a can manufacturing assembly line, thereby providing a one-stop shop for manufacturing cans that satisfy customer needs and demands for resealable, reusable and environmentally friendly cans.

illustrates an exemplary thread forming apparatusin accordance with a non-limiting, exemplary embodiment of the disclosed concept. The exemplary thread forming apparatusis structured to form a plurality of internal threads around a circumference of a can body. The can bodyhas a baseand a sidewallextending from the basein parallel to a central axisof the can bodyand defining an interiorstructured to store a content. The can sidewallhas a rimdefining an opening to the interior.

The thread forming apparatusincludes a punch mechanism, a die mechanismand a number of actuating arrangements. The punch mechanismincludes a punch shaftand a cylindrical punchcoupled to the punch shaft, each rotatable about a punch rotation axis. The punch shaftconnects the cylindrical punchand the number of actuating arrangements, and extends axially therebetween along the punch rotation axis. The cylindrical punchhas a plurality of circumferentially spaced-apart punch projectionsextending radially outward therefrom. Upon actuation, the cylindrical punchis structured to move radially toward the longitudinal axisof the can bodyas shown by the arrowand rotate continuously around the punch rotation axisin a first rotating direction. The die mechanismis disposed adjacent to the punch mechanismand forms a clearancetherebetween suitable to receive the sidewallof the can bodysuch that the sidewallis disposed between the punch mechanismand the die mechanism. The die mechanismincludes a die shaftand a cylindrical diecoupled to the die shaft, each rotatable about a die rotation axis. The die shaftconnects the cylindrical dieand the number of actuating arrangement, and extends axially therebetween along the die rotation axis. The punch and die rotation axesandare disposed parallel to each other and the central axisof the can bodywhen positioned for thread forming. The cylindrical diehas a plurality of circumferentially spaced-apart die recessesextending radially inward. Upon actuation, the cylindrical dieis structured to move radially outward toward the interior of the sidewallof the can bodyas shown by the arrowand rotate continuously around the rotation axisin a second rotating directionopposite the first rotating direction. The number of actuating arrangementsare coupled to the punch mechanismand the die mechanismand structured to translate the punch mechanismand the die mechanism toward the sidewallof the can body and to rotate the punch mechanismand the die mechanismabout the respective rotation axesand. The number of actuating arrangementsmay be any suitable actuating mechanisms (e.g., without limitation, one or more cams). The number of actuating arrangementsmay be a common actuator including a combined cam structured to move the punch mechanismand the die mechanismaxially or individual actuators including separate cams for individually moving the punch mechanismand the die mechanismaxially.

Each punch projectionof the cylindrical punchhas a male thread form geometry (e.g., a protrusion, a protuberance, a ledge or other thread form geometry), and each die recessof the cylindrical diehas a female thread form geometry that is a negative of the male thread form geometry of the punch projection. With the sidewallof the can bodydisposed between the punch projectionand the die recess, pressing the punch projectioninto the die recesscauses the material of the sidewallto flow into the die recessand form an internal thread(see) in the can sidewall. An internal threadprojects inward from the sidewallof the can bodyand has a shape corresponding to the punch projectionand the die recess.

Formation of a plurality of internal threadsaround the circumference of the sidewallof the can bodyis generally shown in. The number of actuating arrangementsare omitted fromfor economy of disclosure, but it will be understood that number of actuating arrangementsmay be employed in any of the disclosed embodiments. Referring now to, the can bodyis being inserted into the clearancebetween the punch mechanismand the die mechanism, as shown by the arrow I. The punch mechanismis translated radially toward the central axisof the can body(as shown by the arrow) and the die mechanismis translated radially toward the inside of the sidewall(as shown by the arrow). The punch mechanism, the die mechanismand the can bodycontinuously and simultaneously rotate in respective directionsandabout respective rotation axes,and. The punch mechanismand the die mechanismrotate at the same speed as the rotation speed of the can body. In, the punch mechanismis disposed such that a first punch projectionis next to the can sidewalland the die mechanismis disposed such that a first die recessis next to the can sidewallopposite the punch projection. In this position, a first internal threadis ready to be formed. To form the first internal thread, the punch mechanismis translated radially toward the sidewallsuch that the first punch projectionis pressed radially toward the sidewalland into the first die recess, thus forming the first internal threadas shown in. As the first internal threadis being formed, the punch mechanism, the die mechanism, and the can bodycontinue to rotate and upon forming of the first internal thread, the first punch projectionrolls out of the first die recessand the newly formed first internal thread(which exits the first die recess), and a next punch projectionrolls into a next die recess, pressing the can sidewallinto the next die recessand forming a next internal thread. The punch mechanism, the die mechanism, and the can bodycontinue to rotate until a last internal threadis formed. Upon forming the last internal thread, the can bodyis released from the apparatus. To release the can body, the punch mechanismand the die mechanismare translated radially away from the can sidewall, as shown by the arrows′ and′, respectively, in.shows the can bodyhaving the newly formed internal threadsaround the circumference of the sidewallreleased from the thread forming apparatus.

illustrates an exemplary thread forming apparatusin accordance with another non-limiting, example embodiment of the disclosed concept. The exemplary thread forming apparatusincludes a punch mechanism, a die mechanism, and a number of actuating arrangements. The punch mechanismincludes a punch shaftand a punchcoupled to one end of the punch shaft. The punch has a convex facestructured to contact the outside of the sidewallof the can body. The die mechanismis disposed adjacent to the punch mechanismand defines a clearancetherebetween suitable to receive the sidewallof the can bodysuch that the sidewallis disposed between the punch mechanismand the die mechanism. The die mechanismhas a die shaftand a diecoupled to one end of the die shaft. The diehas a concave facestructured to contact the inside of the sidewallof the can body.

The number of actuating arrangementsinclude a punch actuatorand a die actuator. The punch actuatorincludes a punch cam assemblyand a punch cam drivestructured to drive the punch cam assembly. The punch cam driveincludes a gear, a cylindrical cam shaft rail, and a cam shaftcoupled to the gearand extending through the cylindrical cam shaft rail. The cam shaftis structured to rotate about the rotation axisin a first directionupon actuation by the gear. The punch cam assemblyincludes a punch cam, a punch cam follower, and a punch return spring. The punch camis coupled to the cam shaft. The punch cammay be, e.g., without limitation, a radial cam structured to rotate upon actuation by the punch cam drive. The punch cam followeris coupled to the punch shaftand engaged with the punch camand is structured to move linearly in response to rotation of the punch cam. The punch cam followermay be, e.g., without limitation, a flat face follower. The punch return springis disposed around the punch shaftand is structured to bias the punchradially away from the sidewallof the can body. As such, upon actuation by the gear, the cam shaftrotates and the rotation of the cam shaftcauses the punch camto rotate. When the lobe of the rotating punch camcontacts the punch cam follower, the punch cam followermoves radially toward the sidewall. After the lobe rotates away, the punch return springcauses the punch cam follower, and the punchcoupled thereto, to move radially away from the sidewall.

The die actuatorincludes a die cam assemblyand a die cam drivestructured to drive the die cam assembly. The die cam driveincludes a gear, a cylindrical cam shaft rail, and a cam shaftcoupled to the gearand extending through the cam shaft rail. The cam shaftis structured to rotate about the rotation axisin the opposite directionto the first directionupon actuation by the gear. The die cam assemblyincludes a die cam, a die cam followerand a die return spring. The die camis coupled to the cam shaft. The die cammay be, e.g., without limitation, a radial cam structured to rotate upon actuation by the die cam drive. The die cam followeris coupled to the die shaftand engaged with the die camand is structured to move linearly in response to rotation of the die cam. The die cam followermay be, e.g., without limitation, a flat face follower. The die return springis disposed around the die shaftand is structured to bias the cylindrical dieradially away from the inside of the sidewallof the can body. As such, upon actuation by the gear, the cam shaftrotates and the rotation of the cam shaftcauses the die camto rotate. When the lobe of the rotating die camcontacts the die cam follower, the die cam followermoves radially toward the sidewall. After the lobe rotates away, the die return springcauses the die cam followerand the dieto move radially away from the inside of the sidewall.

In such example embodiment, neither the punch mechanismnor the die mechanismrotates. Further, the die mechanismmay be fixed radially (with respect to the sidewallor the can body) when thread forming. When positioning for thread forming, however, both the die mechanismand the punch mechanismmay be moved radially toward the sidewall. With the sidewalldisposed between the convex faceof the punchand the concave faceof the die, pressing the convex faceinto the concave facecauses the material of the sidewallof the can bodyto deform into the concave faceand form an internal thread that projects inward from the sidewalland has a shape corresponding to the convex faceand the concave face. Upon forming the internal thread, the return springcauses the convex faceof the punchto move away from the concave faceof the dieand the sidewallwhen not being pressed toward the sidewall. Similarly, the return springcauses the concave faceof the dieto move away from the convex faceof the punchand the inside of the sidewall. Depending on the insertion direction of the can body, the fixed die mechanismmay move radially while the punch mechanismremains radially fixed. The can bodyrotates about its central longitudinal axisand the punchand the diecontinue to form other internal threads along the circumference of the sidewallof the can bodyuntil the last internal thread is formed. Upon forming the last internal thread, the can bodyis released. In some example embodiments of the disclosed concept, the punch mechanismand the fixed die mechanismcan act as one body that move circumferentially in the same direction about the longitudinal axisof the can bodyto form further internal threads while the can bodyremains stationary.

illustrates an example thread forming apparatusin accordance with another non-limiting, example embodiment of the disclosed concept. The example thread forming apparatusincludes a plurality of punch mechanisms, a corresponding plurality of die mechanisms, and an actuator. Each punch mechanismhas a punch shaftand a convex punchcoupled to one end of the punch shaft. A die mechanismis disposed adjacent to each punch mechanismand defines a clearancetherebetween suitable to receive the sidewallof the can bodysuch that the can sidewallis disposed between the punch mechanismand the die mechanism. The die mechanismhas a die shaftand a diehaving a concave facecoupled to one end of the die shaft. The actuatoris a linkage assembly including a main rod, branch rods, a plurality of 4-hinge punch linkagesand a 4-hinge die linkage. The main rodextends radially across a rim of the can bodyand has two legs each coupled to or couplable to a center point of a branch rod. The main rodis structured to be moved axially along the central axisof the can body. The main rodmay have a length equal to the diameter of the rimof the can body. A branch rodextends parallel to the main rodand is structured to be moved axially in parallel to the central axisof the can body. A branch rodhas an inner leg connected to the 4-hinge die linkageand an outer leg connected to a 4-hinge punch linkage. Each leg may be connected to a vertex,of a 4-hinge punch linkageor the 4-hinge die linkage. Each 4-hinge linkage,may have a shape of rhombus. A 4-hinge punch linkageis anchored at a vertexradially opposite the vertexfacing the can sidewall. The 4-hinge punch linkageincludes a guide rodanchored at one endand axially running along the central axis. A punch shaftis connected to a 4-hinge punch linkageat a vertexfacing the can sidewall. A die shaftis connected to the 4-hinge die linkageat a vertexfacing the can sidewall. In some example embodiments, there may be a connecting elementconnecting the inner legs of the branch rodsand the 4-hinge die linkage.

The punch die mechanismmay be radially fixed when forming threads on the can body. When positioning for thread forming, however, both the die mechanismand the punch mechanismmay be moved radially toward the can sidewall. To form internal threads on the can body, a forceis applied axially along the central axisof the can bodytoward the baseupon actuation. The forceis distributed to the branch rodsvia the legs of the main rod, each leg pressing the branch rodat the center point thereof axially toward the base. Pressing the branch rodcauses the 4-hinge punch linkageto radially flatten (partially or fully enough to press the convex punchinto the concave baseof the die) while the 4-hinge die linkageremains fixed. The flattened 4-hinge punch linkagepresses the convex punchinto the concave baseof the dieand pressing the convex punchinto the concave basecauses the can material to flow into the concave baseand form an internal thread in the can sidewall. Depending on the insertion direction of the can body, pressing the branch rodcauses the 4-hinge die linkageto radially flatten (partially or fully enough to press the concave baseof the dieonto the convex punchto form an internal thread on the can sidewall) while the 4-hinge punch linkageremains fixed. The flattened 4-hinge die linkagepresses the concave baseonto the convex punchand pressing the concave baseonto the convex punchcauses the can material to form an internal thread in the can sidewall. In some example embodiments, the punch mechanismand the fixed die mechanismmay be one body moving in the same radial direction. An internal thread projects inward from the sidewallof the can bodyand has a shape corresponding to the convex punchand the concave faceof the die. Upon forming the internal thread, the forceis removed or reversed, causing the convex punchand/or the concave baseof the dieto move radially away from the sidewallwhen not being pressed toward the sidewall. The can bodyis rotated about its central axisand the punchesand the diescontinue to form additional internal threads along the circumference of the can bodyuntil the last pair of internal threads is formed. Upon forming the last internal threads, the can bodyis released.

illustrates an example thread forming apparatusin accordance with yet another non-limiting, example embodiment of the disclosed concept. The exemplary thread forming apparatusincludes a punch mechanism, a die mechanismand an actuator. The punch mechanismhas a punch shaftand a convex punchconnected to one end of the punch shaft. The die mechanismis disposed adjacent to the punch mechanismand defines a clearancetherebetween suitable to receive the sidewallof the can bodysuch that the can sidewallis disposed between the punch mechanismand the die mechanism. The die mechanismhas a die shaftand a diehaving a concave facecoupled to one end of the die shaft. The actuatoris a linkage assembly including a main rod, a branch punch rod, a branch die rod, a punch linking rod, and a die linking rod. The main rodis structured to axially move along the central axisof a can bodywhen positioned for thread forming. The main rodmay be connected to a linkage actuator (e.g., without limitation, a cam drive) at one end and a connectorat the other end. The branch punch rodis connected to the main rodat the connectorand the punch linking rodat a punch sliding connector. The branch punch rodis structured to move axially in parallel to the central axis. The punch linking rodis anchored at a first end and connected to the punch shaftat a second end. The punch linking rodextends radially outwardly at an angle and axially toward the punch mechanism. The punch linking rodis structured to move axially and radially relative to the central axisof the can body. The branch die rodis connected to the main rodat the connectorand the die linking rodat a die sliding connector. The branch die rodis structured to move axially along the central axis. The die linking rodis connected to the die shaftat a second end and includes a punch sliding connectornear a first end. The die linking rodis structured to move axially and radially relative to the central axis.

The die mechanismmay be radially fixed when forming threads on the can body. When positioning for thread forming, however, both the die mechanismand the punch mechanismmay be moved radially toward the sidewallof the can body. To form an internal thread on the can body, a forceis applied axially along the central axistoward the baseof the can bodyupon actuation. The forcepresses the branch rods,axially toward the baseof the can body. Pressing the branch punch rodaxially causes the branch punch rodto slide on the punch linking rodtoward the second end of the punch linking rod. The sliding movement of the branch punch rodcauses the second end of the punch linking rodto move radially toward the can sidewall. The die mechanismremains radially fixed. With the can sidewalldisposed between the convex punchand the concave base, pressing the convex punchinto the concave baseof the diecauses the can material to deform into the concave baseand form an internal thread in the sidewall. An internal thread projects inward from the sidewalland has a shape corresponding to the convex punchand the concave faceof the die. Depending on the insertion direction of the can body, the fixed die mechanismmay be switched to radially move while the punch mechanismremains fixed. In some example embodiments, the punch mechanismand the fixed die mechanismmay be one body moving in the same circumferential direction about the central axis. Upon forming the internal thread, the forceis removed or reversed, causing the convex punchor the concave baseof the dieto move away from the sidewallwhen not being pressed toward the sidewall. The can bodyrotates on its central axisand the punchesand the diescontinue to form additional internal threads along the circumference of the can bodyuntil the last internal thread is formed. Upon forming the last internal thread, the can bodyis released.

It is to be appreciated that while the example embodiments described in detail herein are structured to create internal thread elements on can bodies (i.e., thread elements extending radially inward from the sidewall of the can body), such arrangements may be readily employed to create external thread elements on can bodies (i.e., thread elements extending radially outward from the sidewall of the can body) generally by switching the punch and die components described herein.

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed herein are meant to be illustrative only and not limiting as to the scope of the disclosed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word “comprising” or “including” does not exclude the presence of elements or steps other than those listed in a claim. In any device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The mere fact that certain elements are recited in mutually different dependent claims does not indicate that these elements cannot be used in combination.