HK1078516B - Method and apparatus for making a can lid shell - Google Patents

Description

Method and apparatus for manufacturing can lid shell

Priority requirement

This application claims priority to U.S. patent application No. US10/107,941, filed by james red on 3/27 of 2002, entitled "method and apparatus for making can lid shells" (attorney docket No. MCC02487 PTUS).

Technical Field

The present invention relates to the manufacture of can lids for metal beverage containers and, more particularly, to a new method and apparatus for manufacturing the shell of a can lid in which significantly less force is required in the forming of the can lid shell than in prior art manufacturing methods.

Background

In the retail sale of individual servings of beverages, aluminum cans are widely used as containers. Annual sales of such cans are in the billions and often, as the age changes, the design is improved to reduce cost and improve performance. Additional improvements have been made in the manufacturing processes and equipment used to manufacture such containers to further reduce costs and eliminate scrap and waste.

The method and apparatus of the present invention are particularly suited for making can lid shells with single-action and double-action mechanical presses with newly designed devices. While many variations in application of the basic can lid can be found, the shell of the beverage can lid, which currently includes an outer seaming portion and a connecting portion, has a center panel, countersink, seaming panel. In some arrangements of the can lid, the connecting portion is almost vertical. In the most recent designs of can lids, the connecting portion has been angled from the vertical. Beverage can ends are typically formed from a relatively thin sheet of metal. The formation of a can lid shell is a metal drawing operation. If the shell is made from a circular blank of sheet metal, the lid is formed and shaped using a single action press. If the lid is formed from a preformed cup, the forming and shaping of the lid is accomplished using a double action press.

In an effort to reduce cost and improve performance, the sheet material used to make the cans and lids has become increasingly thinner and the alloys used have become increasingly stronger. Currently, the initial thickness of the material is 0.0088 inches or less, which will continue to decrease as technology advances. As the sheet material used to form the can lid becomes thinner and thinner, the can lid becomes more difficult to manufacture because the thinner the material is more susceptible to wrinkling and cracking during sheet forming, particularly when the can lid is joined at a large angle. While forming a lid with a substantially vertical connecting portion requires about 400-500 pounds of force, it is common in the case forming operation to apply up to 1100 pounds of force in the apparatus to secure such a lid made of existing materials. The increased force required during the forming process accelerates wear of the apparatus, thus requiring increased energy to generate the required force, while requiring increased support to prevent deformation.

Accordingly, there is a need for a method of forming a can lid shell that can better control the high strength, thin thickness material to form the can lid shell while reducing raw material defects, and that requires reduced stamping press and apparatus loads to extend the life of the equipment. In addition, there is a need for apparatus that can accomplish the contemplated can lid shell forming method.

Disclosure of Invention

The object of the present invention is to provide a new device structure and method for manufacturing can lid shells that can be used in both single-action and double-action mechanical presses. The apparatus of the present invention includes an upper die set and a lower die set provided in a conventional die press. The upper and lower punch modules are movable relative to each other to produce the can lid shell. The apparatus of the present invention also includes a forming ring added inside the die set. By adding a forming ring to the die set, the force applied to the metal during the drawing operation can be significantly reduced. Only sufficient force needs to be applied to prevent wrinkling of the can lid shell material, particularly in the area of the seaming panel, and to withstand the panel forming forces. The present invention will be more readily understood from the following detailed description of the drawings showing a prior art process and preferred embodiments of the invention.

Disclosed is a method and apparatus for making a can lid shell having a center panel, a countersink, and a bonding panel comprising a clamping material between a die core ring and a draw pad in a die apparatus using a clamping force of less than 1100 pounds, the die core ring having an outer portion against which the material is clamped, a bonding surface profile, and an inner diameter. The portion of material forming the center panel is engaged in the die set against a die core having an outer diameter that is less than the inner diameter of the die core collar. The die center and the forming ring between the draw pad and the die center move in a direction to form the center panel and the engaging panel. These portions of the housing are formed between the die center, the forming ring and the die core ring, the forming ring providing support and force to the material located between the forming face of the forming ring and the connecting face profile of the die core ring.

Drawings

The accompanying drawings are incorporated in and form a part of the specification to help explain the present invention. The drawings are for purposes of illustration only and are not intended to be a precise description of particular embodiments of the invention. The drawings also illustrate preferred embodiments of how the invention may be made and used, and are not to be construed as limiting the invention to only those illustrated and described examples. The benefits and features of various aspects of the present invention will become more apparent upon consideration of the following drawings:

figure 1 is a side elevation view in cross-section of the prior art apparatus structure during a lid forming operation, illustrating the position of the various operative components at stage 1 of the lid forming operation.

Figure 2 is a side elevation view in cross-section of the apparatus structure of the present invention during a lid forming operation, illustrating the position of the various operative components at stage 1 of the lid forming operation.

Figure 3 is a side elevation view in cross-section of the prior art apparatus structure during a lid forming operation, illustrating the position of the various operative components at stage 2 of the lid forming operation.

Figure 4 is a side elevation view in cross-section of the apparatus structure of the present invention during a lid forming operation, illustrating the position of the various operative components at stage 2 of the lid forming operation.

Figure 5 is a side elevation view in cross-section of the prior art apparatus structure during a lid forming operation, illustrating the position of the various operative components at stage 3 of the lid forming operation.

Figure 6 is a side elevation view in cross-section of the apparatus structure of the present invention during a lid forming operation, illustrating the position of the various operative components at stage 3 of the lid forming operation.

Figure 7 is a side elevation view in cross-section of the prior art apparatus structure during a lid forming operation, illustrating the position of the various operative components at step 4 of the lid forming operation.

Figure 8 is a side elevation view in cross-section of the apparatus structure of the present invention during a lid forming operation, illustrating the position of the various operative components at step 4 of the lid forming operation.

Figure 9 is a side elevation view in cross-section of the prior art apparatus structure during a lid forming operation, illustrating the position of the various operative components at stage 5 of the lid forming operation.

Figure 10 is a side elevation view in cross-section of the apparatus structure of the present invention during a lid forming operation, illustrating the position of the various operative components at step 5 of the lid forming operation.

Fig. 11 is a side elevation view in cross-section of a prior art apparatus configuration during a lid forming operation, illustrating the location of the various operative components in the formation of an annular countersink in the lid.

Fig. 12 is a side elevation view in cross-section of the tooling structure of the present invention during a cap forming operation, illustrating the location of the various operative components in the formation of the annular countersink of the cap.

Detailed Description

In the following, the invention will be described with reference to the drawings showing examples of how the invention may be made and used. The drawings are for purposes of illustration only and are not necessarily a precise scope of an embodiment of the invention. In the drawings, like reference numerals have been used throughout to designate similar or corresponding parts. The specific embodiments illustrated and described herein are exemplary. Many details are well known in the art and therefore neither are shown nor described. It is not desired to limit all illustrated and described details, components, elements, or steps to the invention. Although a number of features and advantages of the invention have been described in the accompanying drawings and in the description thereof, this description is by way of example only, and changes may be made, especially in matters of arrangement, shape and size of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. As used herein, the terms "above," "upward," "below," and "downward" are used to refer to the can lid shell as it would appear when the lid is in its final position on top of the beverage can.

Figure 1 illustrates one embodiment of a known die apparatus 10 for making can lids from a metallic material 22. Those skilled in the art are familiar with the various methods of forming can lids to provide the general structure and geometry of the can lids described herein. The die set 10 includes a die core ring 12, a draw pad 14 and a die core 16. The outer portion of the die core ring 12 that clamps the compacted material against the draw pad 14 has a radius of curvature R1 at the inner curve. Radius of curvature R1 is the machining radius typically used to obtain the desired seaming panel radius for a can lid. The material 22 is held between the die core ring 12 and the draw pad 14 by a force F1 applied to the draw pad 14 of about 1000 to 1200 pounds on the draw pad 14 for lids with the attachment at an angle of inclination and about 400 to 500 pounds on the draw pad 14 for lids with the attachment substantially vertical. A force F1 acts on the material 22 to hold the material 22 in place in a force-bearing zone FA1 between the die core ring 12 and the draw pad 14. The outwardly curved portion of die core ring 12 has a radius of curvature R3. Radius of curvature R3 is a typical machining radius used to obtain the desired seaming panel radius on a can lid. The die core ring 12 has a radius of curvature R7 in the connecting face profile portion. Radius of curvature R7 is the machining radius typically used to achieve the desired seaming panel radius for the can lid. At the edge where the die core 16 joins the material 22, there is a radius of curvature R2. The radius of curvature R2 is the machining radius typically required to obtain the re-draw radius of the lid panel. A radius of curvature R4 is provided at the edge of the die core 16 adjacent the draw pad 14. The radius of curvature R4 and the radius of curvature R7 on the die core ring 12 correspond. The radius of curvature R4 in combination with the radius of curvature R7 form the desired radius of the seaming panel of the can lid.

Figure 2 illustrates one embodiment of the use of metallic material 22 to make can lids for use with the apparatus 110 of the present invention. The apparatus 110 of the present invention includes a die core ring 12, a draw pad 14, a die core 116 and a forming ring 118. The outer portion of the die core ring 12 that grips the material 22 against the draw pad 14 has a radius of curvature R1 at the inner curve. Radius of curvature R1 is the machining radius typically used to achieve the desired seaming panel radius for the can lid. For example, the thickness of the material is 0.0088 inches or less, and the desired radius of the joined panels is between 0.055 and 0.080 inches. The material 22 is held between the die core ring 12 and the draw pad 14 by a force F2 applied to the draw pad 14, the force F2 being about 200 to 300 pounds. A force F2 acts on the material 22 to hold the material 22 in place in a force-bearing zone FA2 between the die core ring 12 and the draw pad 14. The inner diameter of the die core ring 12 has a radius of curvature R3 at the outwardly curved portion. Radius of curvature R3 is the machining radius typically used to achieve the desired seaming panel radius for the can lid. The die core ring 12 has a radius of curvature R7 at the inward curvature of the connecting face profile. Radius of curvature R7 is the machining radius typically used to achieve the desired seaming panel radius for the can lid. At the edge where the die core 116 initially contacts the material 22, there is a radius of curvature R6. Radius of curvature R6 is the machining radius typically used to achieve the desired radius for reforming material 22 into a panel wall. A forming ring 118 is located between the draw pad 14 and the die core 116. The forming ring 118 provides a support surface for the joined portions of the seaming panels during the drawing process to reduce the force required to buckle the can end, particularly when the can end is formed with the joined portions at an angle. The shaped ring 118 also helps prevent deformation of the critical angle and radius formed by the shell during drawing. The forming ring 118 has a radius of curvature R5 near a corner of the draw pad 14 and material 22. The radius of curvature R5 and the radius of curvature R7 on the die core ring 12 correspond. The radius of curvature R5 in combination with the radius of curvature R7 form the desired radius of the seaming panel of the can lid. The die center 116 and forming ring 118 move together toward the material 22 to achieve the configuration shown in fig. 2. The use of the forming ring makes the lid forming process a drawing/re-drawing process as opposed to the drawing process of the prior art. In one embodiment of the invention, a plurality of sets of upper and lower dies are mounted together in a cooperative matrix or pattern to simultaneously produce a set of can lids.

Figure 3 illustrates a second step in the prior art process for making a can lid from metallic material 22 using apparatus 10. The material 22 continues to be held between the die core ring 12 and the draw pad 14 by the force F1 applied to the draw pad 14. The die center 16 continues to move toward the material 22 and a relative force is provided to begin forming the center panel 24 and the seaming panel 26 of the can lid shell by drawing the material 22 at radius R2 on the die core 16 and at radius R1 on the die core ring 12. It can be seen that the portion of material 22 that forms the connecting portion of the splice panel 26 is unsupported during this step.

Figure 4 illustrates one embodiment of the apparatus 110 of the present invention during a second step of forming a can lid from metallic material 22. The material 22 continues to be held between the die core ring 12 and the draw pad 14 by the force F2 applied to the draw pad 14. The die center 116 exerts an opposing force on the material 22 to form the center panel 24 by drawing the material 22 at a radius of curvature R6 on the die center 116. In the formed position shown in fig. 4, the forming ring 118 has been brought into contact with the material 22 and a relative force F3 of about 200 to 400 pounds is applied to the force-bearing area FA3 of the material 22 to form the connecting portion of the can end-engaging panel 26.

Figure 5 illustrates a third step in the prior art process for making a can lid from metallic material 22 using apparatus 10. The material 22 continues to be held between the die core ring 12 and the draw pad 14 by the force F1 applied to the draw pad 14. In the forming position shown in fig. 5, the die center 16 is moved toward the material 22 to continue forming the center panel 24 and seaming panel 26 of the can lid shell. A portion of the die core 16 has moved upward and slightly beyond the inner diameter of the die core ring 12 and drawing of the material 22 continues at the radius of curvature R2 of the die core 16 and the radii of curvature R1 and R3 of the die core ring 12. It can be seen that in the third step of the prior art can lid forming process, the portion of the material 22 forming the connecting portion of the seaming panel 26 is unsupported.

Figure 6 illustrates one embodiment of the apparatus 110 of the present invention at the third stage of forming a can lid from metallic material 22. The material 22 continues to be held between the die core ring 12 and the draw pad 14 by the force F2 applied to the draw pad 14. In the formed position as shown in fig. 6, it is believed that the force F2 is merely sufficient to provide a sufficient force to prevent wrinkling of the splice panel 26. It is believed that the force F2 is not provided for the purpose of drawing the material 22 during lid forming. The die center 116 and forming ring 118 are moved toward the material 22 to further form the center panel 24 and seaming panel 26 of the can lid shell. The force F3 exerted on the material 22 by the forming ring 118 forces the material 22 against the inside diameter and connecting face of the die core ring 12. The material is drawn at the radius of curvature R6 of the die core 116, the radius of curvature R5 of the forming ring 118, the radii of curvature R1, R3 and R7 of the die core ring 12.

Figure 7 illustrates a fourth prior art step of forming a can lid from metallic material 22 using apparatus 10. The material 22 is held between the die core ring 12 and the draw pad 14 by a force F1 applied to the draw pad 14. In the forming position shown in fig. 7, the die core 16 draws the material 22 to form the center panel 24 and seaming panel 26 of the can lid shell. The die core 16 continues to move forward beyond the inner diameter of the die core ring 12 drawing the material 22 at the radius of curvature R2 of the die core 16 and the radii of curvature R1 and R3 of the die core ring 12, at which time the radius of curvature R4 of the die core 16 just contacts the material 22. The initial force to pull and hold the material 22 is demonstrated by force F1. During this step of the forming process, material 22 is subjected to significant stresses and wrinkles, which tend to warp and wrinkle, particularly in the portion of material 22 that is not supported.

Figure 8 illustrates one embodiment of the apparatus 110 of the present invention at a fourth stage in the manufacture of a can lid from metallic material 22. The material 22 is held between the die core ring 12 and the draw pad 14 by a force F2 applied to the draw pad 14. In the formed position as shown in fig. 8, it is believed that the force F2 is the force initially provided to prevent wrinkling of the engagement panel 26, and not the lid forming pull force. The die center 116 draws the material 22 to form the center panel 24 and seaming panel 26 of the can lid shell. The force F3 exerted on the material 22 by the forming ring 118 continues to provide a drawing pressure to the connecting portion of the center panel 24 and the seaming panel 26 forming the shell of the can lid. The die core 116 moves further beyond the inner diameter of the die core ring 12 and drawing of the material 22 continues at the radius of curvature R6 of the die core 116 and the radius of curvature R3 of the die core ring 12.

Figure 9 illustrates a fifth prior art step of forming a can lid from metallic material 22 using apparatus 10. The material 22 is held between the die core ring 12 and the draw pad 14 by a force F1 applied to the draw pad 14. In the forming position shown in fig. 9, the die core 16 draws the material 22 to form the center panel 24 and seaming panel 26 of the can lid shell. The die center 16 moves to its furthest point beyond the inner diameter of the die core ring 12 drawing the material 22 at substantially all points between the die core 16 and the die core ring 12. The amount of force to pull and hold the material 22 is initially supplied by force F1. At this stage of the forming process, the forming of the center panel 24 and the engaging panels 26 is substantially complete.

Figure 10 illustrates one embodiment of the apparatus 110 of the present invention during a fifth stage of forming a can lid from metallic material 22. The material 22 is held between the die core ring 12 and the draw pad 14 by a force F2 applied to the draw pad 14. In the formed position as shown in fig. 10, it is believed that the force F2 is the force provided to prevent wrinkling of the seaming panel 26, and not the force provided to provide the lid forming pull force. The force F3 exerted on the material 22 by the forming ring 118 continues to provide a drawing pressure to the connecting portion of the center panel 24 and the seaming panel 26 forming the shell of the can lid. In the forming position shown in figure 10, the die center 116 has moved to its furthest point beyond the inner diameter of the die core ring 12, substantially completing the formation of the center panel 24 and seaming panel 26 of the can lid shell.

Figure 11 shows the use of die apparatus 10 in the prior art to form an annular countersink 28 of a can lid. The material 22 is held between the die core ring 12 and the draw pad 14 primarily by a force F1 applied to the draw pad 14. During the formation of the annular countersink as shown in figure 11, the die core 16 has a reverse movement, starting away from the die core ring 12. The panel forming punch 38 moves toward the die core ring 12 on the other side of the material 22 opposite the die core 16 to compress the material 22 toward the die core ring 12 to form the annular countersink 28. Although this step in the forming process is described and shown as occurring after the can lid shell is formed, in many forming processes, the formation of the annular countersink occurs at other times in the forming process depending on the production equipment used, but in the same manner as described above.

Fig. 12 illustrates the formation of annular countersink 28 of a can lid in one embodiment of a die apparatus 110 of the present invention. The material 22 is held between the die core ring 12 and the draw pad 14 by a force F2 applied to the draw pad 14 and between the forming ring 118 and the die core ring 12 primarily by a force F3 applied to the forming ring 118. During the forming process, force F3 supported the outer wall of the annular countersink. This substantially prevents deformation of the annular countersink 28 and also ensures formation of a large number of different seaming panels 26 having a variety of different radii of curvature during formation and re-formation of the can end. In the formation of the annular countersink 28 as shown in fig. 12, there is a reverse movement of the die core 116. The panel-forming punch 38 has an outer diameter D1 that is less than the outer diameter D2 of the die center 116 and moves toward the die center collar 12 on the opposite side of the material 22 from the die center 116 to press the material 22 toward the die center collar 12 to form the annular countersink 28. Although this step in the forming process is described and shown as occurring after the can lid shell is formed, in many forming processes, the formation of the annular countersink occurs at other times in the forming process depending on the production equipment used, but in the same manner as described herein.

The specific embodiments shown and described above are exemplary. Many details are often found in the prior art and thus such details are neither shown nor described. It is not desired to state that all of the details, components, elements or steps shown and described herein are inventive in the present invention. Although a number of features and advantages of the invention have been described in the accompanying drawings and description thereof, the description is by way of example only, and changes may be made in detail, especially in matters of arrangement, shape and size of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

The above detailed description of specific examples and the accompanying drawings are not intended to be exhaustive or to limit the invention to the precise form disclosed, and are provided as at least one illustrative example of how the invention may be practiced and carried out. The limits of the invention and the scope of protection of this patent are defined and set forth in the following claims.

Having thus described the present invention by reference to certain of its preferred embodiments, it is to be understood that the particular embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, for example, some features of the present invention may not be correspondingly employed with other features. Many such variations and modifications may be apparent and desirable to those skilled in the art based upon a review of the foregoing description of preferred embodiments of the invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims (6)

1. A method for manufacturing a shell for a can lid, the shell comprising a center panel, a countersink, and a seaming panel, the seaming panel comprising a connecting portion and an outer portion, the method comprising:

retaining the material (22) between the die core ring (12) and the draw pad (14) in the die apparatus (110) by applying a force to the draw pad (14) in the direction of the material (22) just sufficient to retain the material (22) between the die core ring (12) and the draw pad (14), the die core ring (12) having an outside portion, a connecting face profile and an inside diameter;

engaging the portion of the material (22) forming the center panel against a die core (116) in a die set (110), the die core (116) having an outer diameter that is less than an inner diameter of a die core ring (12);

forming a center panel of the can lid shell by applying opposing forces to the die core (116) to move the die core (116) in one direction;

moving a forming ring (118) having a forming surface between the draw pad (14) and the die core (116) until the forming surface of the forming ring (118) engages the material (22) that will form the connecting portion of the seaming panel of the can lid shell;

applying a force to the forming ring (118) in the direction of the material (22) to form a connecting portion of the can lid shell seaming panel between the connecting face profile of the die core ring (12) and the forming face of the forming ring (118);

continuing to apply a force to the draw pad (14) just sufficient to hold the material (22) between the die core ring (12) and the draw pad (14) and prevent wrinkling of the can lid shell engaging panel;

as the shaping ring (118) continues to provide support and force to the material (22) between the shaping face of the shaping ring (118) and the connecting face profile of the die core ring (12), the die core (116) is moved further in one direction to form the center panel.

Reversing the movement of the die core (116);

engaging a central panel of material with a panel forming punch (38), the panel forming punch (38) having an outer diameter less than the outer diameter of the die core (116);

as the forming ring (118) continues to provide support and force to the material (22) between the forming face of the forming ring (118) and the connecting face profile of the die core ring (12), the offset forming punch (38) is moved in a direction toward the material (22) to form the countersink.

2. The method of claim 1, wherein: the formation of the countersink occurs prior to other steps in the can lid shell manufacturing process.

3. A lid for an aluminum can made by the method of claim 1.

4. An apparatus for manufacturing a can lid shell, comprising:

a die core ring having an outer portion with a material contacting surface, a connecting surface profile and an inner diameter;

a draw pad having an outer diameter, an inner diameter, and a material contacting surface;

a first force assembly operatively connected to the draw pad for applying a force sufficient to secure the can lid shell between the material contacting surface of the die core ring and the material contacting surface of the draw pad;

a die core having an outer diameter less than the inner diameter of the die core collar;

a forming ring comprising an inner diameter, an outer diameter, and a forming surface;

a second force assembly operatively connected to the forming ring;

a panel forming punch having an outer diameter smaller than the outer diameter of the die core; and

a third force assembly operatively connected to the face plate forming the punch.

5. The apparatus of claim 4, wherein: the first force assembly provides a force of less than 1100 pounds.

6. The apparatus of claim 4, wherein: the second force assembly provides a force of less than 1100 pounds.