Thread Forming Apparatus And Associated Method

Abstract

A thread forming apparatus includes a punch mechanism including a punch shaft and a cylindrical punch 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 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 an actuator connected to the punch shaft and the die shaft and structured to rotate and radially move 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.

Claims

1. 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, the thread forming apparatus comprising: 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.

2. The thread forming apparatus of claim 1, wherein each punch projection comprises a male thread form geometry and comprises a protrusion, a protuberance, or a ledge, and wherein each die recess comprises a female thread form geometry that is a negative of the male thread form geometry.

3. The thread forming apparatus of claim 1, wherein the cylindrical punch is positioned and structured to engage an outer surface of the sidewall of the can body and wherein the cylindrical die is positioned and structured to engage an inner surface of the sidewall of the can body.

4. The thread forming apparatus of claim 1, wherein the cylindrical punch is positioned and structured to engage an inner surface of the sidewall of the can body and wherein the cylindrical die is positioned and structured to engage an outer surface of the sidewall of the can body.

5. A thread forming apparatus structured to form a plurality of threads on a can body having a base and sidewall extending from the base, the thread forming apparatus comprising: 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 with respect to a longitudinal axis of the can body; a die mechanism including a die shaft and a die having a concave face coupled to the die shaft, the die mechanism being structured to be moved radially with respect to the longitudinal axis; and a number of actuator arrangements connected to the punch shaft and the die shaft and structured to move the punch mechanism and the die mechanism radially relative to the longitudinal axis of the can body for forming a plurality of threads on the can body.

6. The apparatus of claim 5, wherein the number of actuating arrangements includes a punch actuator and a die actuator, the punch actuator including a punch cam assembly and a punch cam drive structured to drive the punch cam assembly, the die actuator including a die cam assembly and a die cam drive structured to drive the die cam assembly.

7. The apparatus of claim 5, wherein the actuator is a linkage assembly including a main rod structured to be moved axially along the central axis, branch rods connected to the main rod and structured to be moved axially parallel to the central axis, a plurality of 4-hinge punch linkages connected to the branch rods and the punch shaft and structured to cause the punch shaft to be moved radially toward the can sidewall, the radial movement of the punch shaft causing the convex shaped punch to be pressed into the concave base of the die, and a 4-hinge die linkage connected to the branch rods and the die shaft and structured to cause the die to move radially toward the can sidewall.

8. The apparatus of claim 5, wherein the actuator is a linkage assembly including a main rod structured to move axially along the central axis of the can body, a branch punch rod connected to the main rod and structured to move axially parallel to the central axis, a branch die rod connected to the main rod and structured to move axially along the central axis, a punch linking rod connected to the branch punch rod at a punch sliding connector at a first end and to the punch shaft at a second end, and a die linking rod having a first end and a second end connected to the die shaft, the die linking rod being connected to the branch die rod at a die sliding connector, the punch linking rod and the die linking rod extending parallel to each other and radially outward from the central axis at an angle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

[0010] FIG. 1 is a partially schematic view of an example thread forming apparatus in accordance with a non-limiting, example embodiment of the disclosed concept shown positioned adjacent a sectional view of a portion of a can body;

[0011] FIG. 2 is a partially schematic sectional side view of a can body disposed adjacent to a thread forming apparatus before the can body is inserted into the thread forming apparatus in accordance with a non-limiting, example embodiment of the disclosed concept;

[0012] FIG. 3 is another view of the thread forming apparatus and can body of FIG. 2 shown with the can body positioned for thread forming by the thread forming apparatus;

[0013] FIG. 4 is another view of the thread forming apparatus and can body of FIGS. 2 and 3 shown with the can body undergoing a thread formation by the thread forming apparatus;

[0014] FIG. 5 is another view of the thread forming apparatus and can body of FIGS. 2-4 shown with portions of the thread forming apparatus radially retracted to allow for withdrawal of the can body from the apparatus after having a plurality of threads formed therein;

[0015] FIG. 6 is another view of the thread forming apparatus and can body of FIGS. 2-6 shown with the can body withdrawn from the thread forming apparatus after having a plurality of threads formed therein; and

[0016] FIGS. 7-9 are partially schematic, sectional views of other example thread forming apparatus in accordance with non-limiting, example embodiments of the disclosed concept.

DETAILED DESCRIPTION OF THE INVENTION

[0017] 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.

[0018] As used herein, the singular form of a, an, and the include plural references unless the context clearly dictates otherwise.

[0019] 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].

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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].

[0025] 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.

[0026] As used herein, an elongated element inherently includes a longitudinal axis and/or longitudinal line extending in the direction of the elongation.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] FIG. 1 illustrates an exemplary thread forming apparatus 100 in accordance with a non-limiting, exemplary embodiment of the disclosed concept. The exemplary thread forming apparatus 100 is structured to form a plurality of internal threads around a circumference of a can body 10. The can body 10 has a base 12 and a sidewall 13 extending from the base 12 in parallel to a central axis 2 of the can body 10 and defining an interior 14 structured to store a content. The can sidewall 13 has a rim 15 defining an opening to the interior 14.

[0032] The thread forming apparatus 100 includes a punch mechanism 110, a die mechanism 130 and a number of actuating arrangements 150. The punch mechanism 110 includes a punch shaft 112 and a cylindrical punch 114 coupled to the punch shaft 112, each rotatable about a punch rotation axis 3. The punch shaft 112 connects the cylindrical punch 114 and the number of actuating arrangements 150, and extends axially therebetween along the punch rotation axis 3. The cylindrical punch 114 has a plurality of circumferentially spaced-apart punch projections 120 extending radially outward therefrom. Upon actuation, the cylindrical punch 114 is structured to move radially toward the longitudinal axis 2 of the can body 10 as shown by the arrow 4 and rotate continuously around the punch rotation axis 3 in a first rotating direction 5. The die mechanism 130 is disposed adjacent to the punch mechanism 110 and forms a clearance 6 therebetween suitable to receive the sidewall 13 of the can body 10 such that the sidewall 13 is disposed between the punch mechanism 110 and the die mechanism 130. The die mechanism 130 includes a die shaft 132 and a cylindrical die 134 coupled to the die shaft 132, each rotatable about a die rotation axis 7. The die shaft 132 connects the cylindrical die 134 and the number of actuating arrangement 150, and extends axially therebetween along the die rotation axis 7. The punch and die rotation axes 3 and 7 are disposed parallel to each other and the central axis 2 of the can body 10 when positioned for thread forming. The cylindrical die 134 has a plurality of circumferentially spaced-apart die recesses 140 extending radially inward. Upon actuation, the cylindrical die 134 is structured to move radially outward toward the interior of the sidewall 13 of the can body 10 as shown by the arrow 8 and rotate continuously around the rotation axis 7 in a second rotating direction 9 opposite the first rotating direction 5. The number of actuating arrangements 150 are coupled to the punch mechanism 110 and the die mechanism 130 and structured to translate the punch mechanism 110 and the die mechanism toward the sidewall 13 of the can body and to rotate the punch mechanism 110 and the die mechanism 130 about the respective rotation axes 3 and 7. The number of actuating arrangements 150 may be any suitable actuating mechanisms (e.g., without limitation, one or more cams). The number of actuating arrangements 150 may be a common actuator including a combined cam structured to move the punch mechanism 110 and the die mechanism 130 axially or individual actuators including separate cams for individually moving the punch mechanism 110 and the die mechanism 130 axially.

[0033] Each punch projection 120 of the cylindrical punch 114 has a male thread form geometry (e.g., a protrusion, a protuberance, a ledge or other thread form geometry), and each die recess 140 of the cylindrical die 134 has a female thread form geometry that is a negative of the male thread form geometry of the punch projection 120. With the sidewall 13 of the can body 10 disposed between the punch projection 120 and the die recess 140, pressing the punch projection 120 into the die recess 140 causes the material of the sidewall 13 to flow into the die recess 140 and form an internal thread 11 (see FIG. 4) in the can sidewall 13. An internal thread 11 projects inward from the sidewall 13 of the can body 10 and has a shape corresponding to the punch projection 120 and the die recess 140.

[0034] Formation of a plurality of internal threads 11 around the circumference of the sidewall 13 of the can body 10 is generally shown in FIGS. 2-6. The number of actuating arrangements 150 are omitted from FIGS. 2-6 for economy of disclosure, but it will be understood that number of actuating arrangements 150 may be employed in any of the disclosed embodiments. Referring now to FIG. 2, the can body 10 is being inserted into the clearance 6 between the punch mechanism 110 and the die mechanism 130, as shown by the arrow I. The punch mechanism 110 is translated radially toward the central axis 2 of the can body 10 (as shown by the arrow 4) and the die mechanism 130 is translated radially toward the inside of the sidewall 13 (as shown by the arrow 8). The punch mechanism 110, the die mechanism 130 and the can body 10 continuously and simultaneously rotate in respective directions 5 and 9 about respective rotation axes 3, 7 and 2. The punch mechanism 110 and the die mechanism 130 rotate at the same speed as the rotation speed of the can body 10. In FIG. 3, the punch mechanism 110 is disposed such that a first punch projection 120 is next to the can sidewall 13 and the die mechanism 130 is disposed such that a first die recess 140 is next to the can sidewall 13 opposite the punch projection 120. In this position, a first internal thread 11 is ready to be formed. To form the first internal thread 11, the punch mechanism 110 is translated radially toward the sidewall 13 such that the first punch projection 120 is pressed radially toward the sidewall 13 and into the first die recess 140, thus forming the first internal thread 11 as shown in FIG. 4. As the first internal thread 11 is being formed, the punch mechanism 110, the die mechanism 130, and the can body 10 continue to rotate and upon forming of the first internal thread 11, the first punch projection 120 rolls out of the first die recess 140 and the newly formed first internal thread 11 (which exits the first die recess 140), and a next punch projection 120 rolls into a next die recess 140, pressing the can sidewall 13 into the next die recess 140 and forming a next internal thread 11. The punch mechanism 110, the die mechanism 130, and the can body 10 continue to rotate until a last internal thread 11 is formed. Upon forming the last internal thread 11, the can body 10 is released from the apparatus 100. To release the can body 10, the punch mechanism 110 and the die mechanism 130 are translated radially away from the can sidewall 13, as shown by the arrows 4 and 8, respectively, in FIG. 5. FIG. 6 shows the can body 10 having the newly formed internal threads 11 around the circumference of the sidewall 13 released from the thread forming apparatus 100.

[0035] FIG. 7 illustrates an exemplary thread forming apparatus 200 in accordance with another non-limiting, example embodiment of the disclosed concept. The exemplary thread forming apparatus 200 includes a punch mechanism 210, a die mechanism 230, and a number of actuating arrangements 250. The punch mechanism 210 includes a punch shaft 212 and a punch 214 coupled to one end of the punch shaft 212. The punch has a convex face 220 structured to contact the outside of the sidewall 13 of the can body 10. The die mechanism 230 is disposed adjacent to the punch mechanism 210 and defines a clearance 6 therebetween suitable to receive the sidewall 13 of the can body 10 such that the sidewall 13 is disposed between the punch mechanism 210 and the die mechanism 230. The die mechanism 230 has a die shaft 232 and a die 234 coupled to one end of the die shaft 232. The die 234 has a concave face 240 structured to contact the inside of the sidewall 13 of the can body 10.

[0036] The number of actuating arrangements 250 include a punch actuator 260 and a die actuator 280. The punch actuator 260 includes a punch cam assembly 261 and a punch cam drive 270 structured to drive the punch cam assembly 261. The punch cam drive 270 includes a gear 271, a cylindrical cam shaft rail 273, and a cam shaft 272 coupled to the gear 271 and extending through the cylindrical cam shaft rail 273. The cam shaft 272 is structured to rotate about the rotation axis 3 in a first direction 6 upon actuation by the gear 271. The punch cam assembly 261 includes a punch cam 262, a punch cam follower 263, and a punch return spring 264. The punch cam 262 is coupled to the cam shaft 272. The punch cam 262 may be, e.g., without limitation, a radial cam structured to rotate upon actuation by the punch cam drive 270. The punch cam follower 263 is coupled to the punch shaft 212 and engaged with the punch cam 262 and is structured to move linearly in response to rotation of the punch cam 262. The punch cam follower 263 may be, e.g., without limitation, a flat face follower. The punch return spring 264 is disposed around the punch shaft 212 and is structured to bias the punch 214 radially away from the sidewall 13 of the can body 10. As such, upon actuation by the gear 271, the cam shaft 272 rotates and the rotation of the cam shaft 272 causes the punch cam 262 to rotate. When the lobe of the rotating punch cam 262 contacts the punch cam follower 263, the punch cam follower 263 moves radially toward the sidewall 13. After the lobe rotates away, the punch return spring 264 causes the punch cam follower 263, and the punch 214 coupled thereto, to move radially away from the sidewall 13.

[0037] The die actuator 280 includes a die cam assembly 281 and a die cam drive 290 structured to drive the die cam assembly 281. The die cam drive 290 includes a gear 291, a cylindrical cam shaft rail 293, and a cam shaft 292 coupled to the gear 291 and extending through the cam shaft rail 293. The cam shaft 292 is structured to rotate about the rotation axis 7 in the opposite direction 9 to the first direction 5 upon actuation by the gear 291. The die cam assembly 281 includes a die cam 282, a die cam follower 283 and a die return spring 284. The die cam 282 is coupled to the cam shaft 292. The die cam 282 may be, e.g., without limitation, a radial cam structured to rotate upon actuation by the die cam drive 290. The die cam follower 283 is coupled to the die shaft 232 and engaged with the die cam 282 and is structured to move linearly in response to rotation of the die cam 282. The die cam follower 283 may be, e.g., without limitation, a flat face follower. The die return spring 284 is disposed around the die shaft 232 and is structured to bias the cylindrical die 234 radially away from the inside of the sidewall 13 of the can body 10. As such, upon actuation by the gear 291, the cam shaft 292 rotates and the rotation of the cam shaft 292 causes the die cam 282 to rotate. When the lobe of the rotating die cam 282 contacts the die cam follower 283, the die cam follower 283 moves radially toward the sidewall 13. After the lobe rotates away, the die return spring 284 causes the die cam follower 283 and the die 234 to move radially away from the inside of the sidewall 13.

[0038] In such example embodiment, neither the punch mechanism 210 nor the die mechanism 230 rotates. Further, the die mechanism 230 may be fixed radially (with respect to the sidewall 13 or the can body 10) when thread forming. When positioning for thread forming, however, both the die mechanism 230 and the punch mechanism 210 may be moved radially toward the sidewall 13. With the sidewall 13 disposed between the convex face 220 of the punch 214 and the concave face 240 of the die 234, pressing the convex face 220 into the concave face 240 causes the material of the sidewall 13 of the can body 10 to deform into the concave face 240 and form an internal thread that projects inward from the sidewall 13 and has a shape corresponding to the convex face 220 and the concave face 240. Upon forming the internal thread, the return spring 264 causes the convex face 220 of the punch 214 to move away from the concave face 240 of the die 234 and the sidewall 13 when not being pressed toward the sidewall 13. Similarly, the return spring 284 causes the concave face 240 of the die 234 to move away from the convex face 220 of the punch 214 and the inside of the sidewall 13. Depending on the insertion direction of the can body 10, the fixed die mechanism 230 may move radially while the punch mechanism 210 remains radially fixed. The can body 10 rotates about its central longitudinal axis 2 and the punch 214 and the die 234 continue to form other internal threads along the circumference of the sidewall 13 of the can body 10 until the last internal thread is formed. Upon forming the last internal thread, the can body 10 is released. In some example embodiments of the disclosed concept, the punch mechanism 210 and the fixed die mechanism 230 can act as one body that move circumferentially in the same direction about the longitudinal axis 2 of the can body 10 to form further internal threads while the can body 10 remains stationary.

[0039] FIG. 8 illustrates an example thread forming apparatus 300 in accordance with another non-limiting, example embodiment of the disclosed concept. The example thread forming apparatus 300 includes a plurality of punch mechanisms 310, a corresponding plurality of die mechanisms 330, and an actuator 350. Each punch mechanism 310 has a punch shaft 312 and a convex punch 314 coupled to one end of the punch shaft 312. A die mechanism 330 is disposed adjacent to each punch mechanism 310 and defines a clearance 6 therebetween suitable to receive the sidewall 13 of the can body 10 such that the can sidewall 13 is disposed between the punch mechanism 310 and the die mechanism 330. The die mechanism 330 has a die shaft 332 and a die 334 having a concave face 340 coupled to one end of the die shaft 332. The actuator 350 is a linkage assembly including a main rod 351, branch rods 352, a plurality of 4-hinge punch linkages 360 and a 4-hinge die linkage 370. The main rod 351 extends radially across a rim of the can body 10 and has two legs each coupled to or couplable to a center point of a branch rod 352. The main rod 351 is structured to be moved axially along the central axis 3 of the can body 10. The main rod 351 may have a length equal to the diameter of the rim 15 of the can body 10. A branch rod 352 extends parallel to the main rod 351 and is structured to be moved axially in parallel to the central axis 3 of the can body 10. A branch rod 352 has an inner leg connected to the 4-hinge die linkage 370 and an outer leg connected to a 4-hinge punch linkage 360. Each leg may be connected to a vertex 361, 371 of a 4-hinge punch linkage 360 or the 4-hinge die linkage 370. Each 4-hinge linkage 360, 370 may have a shape of rhombus. A 4-hinge punch linkage 360 is anchored at a vertex 363 radially opposite the vertex 362 facing the can sidewall 13. The 4-hinge punch linkage 370 includes a guide rod 356 anchored at one end 357 and axially running along the central axis 3. A punch shaft 312 is connected to a 4-hinge punch linkage 360 at a vertex 362 facing the can sidewall 13. A die shaft 332 is connected to the 4-hinge die linkage 370 at a vertex 372 facing the can sidewall 13. In some example embodiments, there may be a connecting element 354 connecting the inner legs of the branch rods 352 and the 4-hinge die linkage 370.

[0040] The punch die mechanism 330 may be radially fixed when forming threads on the can body 10. When positioning for thread forming, however, both the die mechanism 330 and the punch mechanism 310 may be moved radially toward the can sidewall 13. To form internal threads on the can body 13, a force 355 is applied axially along the central axis 3 of the can body 10 toward the base 12 upon actuation. The force 355 is distributed to the branch rods 352 via the legs of the main rod 351, each leg pressing the branch rod 352 at the center point thereof axially toward the base 12. Pressing the branch rod 352 causes the 4-hinge punch linkage 360 to radially flatten (partially or fully enough to press the convex punch 314 into the concave base 340 of the die 334) while the 4-hinge die linkage 370 remains fixed. The flattened 4-hinge punch linkage 360 presses the convex punch 314 into the concave base 340 of the die 334 and pressing the convex punch 314 into the concave base 340 causes the can material to flow into the concave base 340 and form an internal thread in the can sidewall 13. Depending on the insertion direction of the can body 10, pressing the branch rod 352 causes the 4-hinge die linkage 370 to radially flatten (partially or fully enough to press the concave base 340 of the die 334 onto the convex punch 314 to form an internal thread on the can sidewall 13) while the 4-hinge punch linkage 360 remains fixed. The flattened 4-hinge die linkage 370 presses the concave base 340 onto the convex punch 314 and pressing the concave base 340 onto the convex punch 314 causes the can material to form an internal thread in the can sidewall 13. In some example embodiments, the punch mechanism 310 and the fixed die mechanism 330 may be one body moving in the same radial direction. An internal thread projects inward from the sidewall 13 of the can body 10 and has a shape corresponding to the convex punch 314 and the concave face 340 of the die 334. Upon forming the internal thread, the force 355 is removed or reversed, causing the convex punch 314 and/or the concave base 340 of the die 334 to move radially away from the sidewall 13 when not being pressed toward the sidewall 13. The can body 10 is rotated about its central axis 2 and the punches 314 and the dies 334 continue to form additional internal threads along the circumference of the can body 10 until the last pair of internal threads is formed. Upon forming the last internal threads, the can body 10 is released.

[0041] FIG. 9 illustrates an example thread forming apparatus 400 in accordance with yet another non-limiting, example embodiment of the disclosed concept. The exemplary thread forming apparatus 400 includes a punch mechanism 410, a die mechanism 430 and an actuator 450. The punch mechanism 410 has a punch shaft 412 and a convex punch 414 connected to one end of the punch shaft 412. The die mechanism 430 is disposed adjacent to the punch mechanism 410 and defines a clearance 6 therebetween suitable to receive the sidewall 13 of the can body 10 such that the can sidewall 13 is disposed between the punch mechanism 410 and the die mechanism 430. The die mechanism 430 has a die shaft 432 and a die 434 having a concave face 440 coupled to one end of the die shaft 432. The actuator 450 is a linkage assembly including a main rod 461, a branch punch rod 471, a branch die rod 481, a punch linking rod 472, and a die linking rod 482. The main rod 461 is structured to axially move along the central axis 2 of a can body 10 when positioned for thread forming. The main rod 461 may be connected to a linkage actuator (e.g., without limitation, a cam drive) at one end and a connector 451 at the other end. The branch punch rod 471 is connected to the main rod 461 at the connector 451 and the punch linking rod 472 at a punch sliding connector 473. The branch punch rod 471 is structured to move axially in parallel to the central axis 2. The punch linking rod 472 is anchored at a first end and connected to the punch shaft 412 at a second end. The punch linking rod 472 extends radially outwardly at an angle and axially toward the punch mechanism 410. The punch linking rod 472 is structured to move axially and radially relative to the central axis 2 of the can body 10. The branch die rod 481 is connected to the main rod 461 at the connector 451 and the die linking rod 482 at a die sliding connector 483. The branch die rod 481 is structured to move axially along the central axis 3. The die linking rod 482 is connected to the die shaft 432 at a second end and includes a punch sliding connector 483 near a first end. The die linking rod 482 is structured to move axially and radially relative to the central axis 2.

[0042] The die mechanism 430 may be radially fixed when forming threads on the can body 10. When positioning for thread forming, however, both the die mechanism 430 and the punch mechanism 410 may be moved radially toward the sidewall 13 of the can body 10. To form an internal thread on the can body 10, a force 455 is applied axially along the central axis 2 toward the base 12 of the can body 10 upon actuation. The force 455 presses the branch rods 471,481 axially toward the base 12 of the can body 10. Pressing the branch punch rod 471 axially causes the branch punch rod 471 to slide on the punch linking rod 472 toward the second end of the punch linking rod 472. The sliding movement of the branch punch rod 471 causes the second end of the punch linking rod 472 to move radially toward the can sidewall 13. The die mechanism 430 remains radially fixed. With the can sidewall 13 disposed between the convex punch 414 and the concave base 440, pressing the convex punch 414 into the concave base 440 of the die 434 causes the can material to deform into the concave base 440 and form an internal thread in the sidewall 13. An internal thread projects inward from the sidewall 13 and has a shape corresponding to the convex punch 414 and the concave face 440 of the die 434. Depending on the insertion direction of the can body 10, the fixed die mechanism 430 may be switched to radially move while the punch mechanism 410 remains fixed. In some example embodiments, the punch mechanism 410 and the fixed die mechanism 430 may be one body moving in the same circumferential direction about the central axis 2. Upon forming the internal thread, the force 455 is removed or reversed, causing the convex punch 414 or the concave base 440 of the die 434 to move away from the sidewall 13 when not being pressed toward the sidewall 13. The can body 10 rotates on its central axis 3 and the punches 414 and the dies 434 continue to form additional internal threads along the circumference of the can body 10 until the last internal thread is formed. Upon forming the last internal thread, the can body 10 is released.

[0043] 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.

[0044] 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.

[0045] 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.