Reinforced metal container and method for making same

Abstract

An improved pail is provided which comprises a curl having a reinforcement member preferably made of plastic mounted therein. The invention further provides a curl press machine which comprises an upper curl die and a lower curl die comprised of radially translating segments. Each lower curl die segment has a tabular end received in a curved slot of a rotating actuator ring. As the actuator ring rotates, the lower curl die segments radially translate. The lower curl die segments further function to support the reinforcement member which reinforces the curl of the pail.

Description

FIELD OF THE INVENTION

[0001] This invention relates in general to product packaging and more specifically to a reinforced metal container and method for making same.

BACKGROUND OF THE INVENTION

[0002] When chemicals are transported they need to be placed in a container that will ensure that the chemicals will not leak into the surrounding environment in order to avoid health, safety, and environmental problems. Therefore, before dangerous chemicals are shipped, the container in which the dangerous chemicals are placed must be able to pass the required safety tests to ensure that the dangerous chemicals will not leak from the container, even when the container has been damaged. One of the standardized tests that is imposed by the Federal Department of Transportation on containers used in shipping dangerous or hazardous chemicals is referred to as the ‘drop test.’ In order to pass the drop test, the container must not leak after it is dropped from a height proportional to the chemical's specific gravity onto a non-yielding surface. In particular, for steel pails, the drop test must be passed for two different orientations of the container.

[0003] In the first orientation, the center of gravity is aligned with the point of impact and the bottom chime of the steel pail.

[0004] In the second orientation, the center of gravity is aligned with the point of impact and the top chime of the container. The dropped samples are then observed for any leakage of the dangerous chemicals.

[0005] Pails dropped in the second orientation typically fail when the lid crunches or deforms the curl causing the curl to collapse and lose strength. It is known in the prior art that reinforcement of the curls of large containers with steel wire was effective. Curls of steel pails are not reinforced with steel wire today because they are manufactured by automated machinery and reinforcement with steel wire requires manual labor. Thus it is too expensive to reinforce the curl because of the material costs and the manual labor costs. Thus, a pail assembly having a reinforced curl which overcome the above described disadvantages is desired.

DETAILED DESCRIPTION OF THE FIGURES

[0006] In the accompanying figures:

[0007] FIG. 1 is a front view of a curl press machine of the present invention;

[0008] FIG. 2 is a section view in the direction 2-2 of FIG. 1;

[0009] FIG. 3 is a section view in the direction 3-3 of FIG. 2 wherein the iris is shown in the open or unengaged position;

[0010] FIG. 4 is a section view in the direction 3-3 of FIG. 2 wherein the iris is shown in the closed or engaged position;

[0011] FIG. 5 is a section view in the direction 3-3 of FIG. 2 wherein the iris is shown in the closed position and the pail is undergoing the press operation in order to form the curl;

[0012] FIG. 6 is a section view in the direction 6-6 of FIG. 3 wherein the actuator and the iris are in the open position;

[0013] FIG. 7 is a section view in the direction 7-7 of FIG. 4 wherein the actuator and the iris are in the closed position; and

[0014] FIG. 8 is an enlarged section view of the denoted area in FIG. 3;

[0015] FIG. 9 is an enlarged section view of the denoted area in FIG. 4;

[0016] FIG. 10 is an enlarged section view of the denoted area in FIG. 5;

[0017] FIG. 11A is a perspective view of a steel pail and lid assembly of the present invention; and

[0018] FIG. 11B is an enlarged cut away view of a reinforced curl and lid as shown in FIG. 11A.

DETAILED DESCRIPTION OF THE INVENTION

[0019] As shown in the attached FIGS. 1-10, a curl press machine of the present invention is shown generally at 10. The curl press machine forms a reinforced curl on a prefabricated metal pail in an automated process. The curl press machine 10 includes a conveyor belt 20 for transporting a plurality of steel pail shells 22 to the press 30. The steel pail shells 22 are loaded onto the press 30 so that the upper rim 23 of the pail is aligned for engagement with upper and lower curl dies 40, 42. The curl is formed by pressing the upper rim 23 of the pail in a longitudinal direction into the upper and lower curl dies 40,42. The upper curl die 40 is generally an annular ring and has a cross-sectional shape as shown in FIG. 8. The upper curl die 40 is mounted to the upper portion of the press 32. The upper curl die 40 has a leading edge 44 for guiding the rim 23 of the pail shell 22 into a circular portion 46 of the upper curl die 40.

[0020] The lower curl die 42 is comprised of a plurality of annular segments 42 which radially traverse inward into a closed or engaged position as shown in FIGS. 7 and 9 from an outward open position as shown in FIGS. 6 and 8. Each annular segment 42 has an extension 50 which is received within a radial groove 52 of the upper die 40. Each of the radial grooves 52 guide the radial translation of the annular segments. Each annular segment further comprises a tabular end 54 which is received in a curved slot 56 of an actuator ring 60. The actuator ring 60 is slidably received within a flange 34 of the press assembly 10. The actuator ring 60 has an extension 62 which is connected to a telescoping actuator 70. As shown in FIGS. 4, 6 and 7, when the actuator's linkage 72 telescopes, the ring 60 rotates about the longitudinal axis of the press. As the ring 60 rotates, the tabular ends 54 of the lower curl die 42 slide in the curved slots 56, causing the annular segments of the lower curl die 42 to move radially inward. The lower curl die extensions 50 track within the upper curl die groove 52 to prevent the annular segments from rotating. The curvature and orientation of the curved slots 56 of the actuator ring 60 are shaped and oriented as best shown in FIG. 6 to allow the annular segments to translate radially inward and outward. The curved slots are preferably oriented tangentially. The curved slots are not limited to the geometrical shape and orientation as shown in FIG. 6 as other shapes and orientations of the slots would work for the invention.

[0021] As shown in FIG. 8, the lower curl die 42 further comprises a curved portion 48 which functions to shape the curl of the pail and load the curl with a reinforcement member 80 during formation of the curl. The curved portion 48 of the lower curl die 42 aligns with the curved portion 46 of the upper curl die 40 when the annular segments are in the radially inward or engaged position as shown in FIG. 9. As the rim 23 of the pail 22 is pressed into the upper curl die 40, the rim 23 curls along the circular portion 46 of the upper curl die 40 and then down into the aligned curved section 48 around the reinforcement member 80 as shown in FIG. 10.

[0022] The reinforcement member 80 may comprise metal wire, plastic cord or other suitable material. Preferably, the reinforcement member has a circular cross section and comprises high density polyethylene. It is believed that plastic has an advantage over steel wire in that it will slide in the curl upon impact, thereby transferring the impact energy around the pail in order to dissipate the energy. Metal wire, while providing curl reinforcement, will not dissipate the energy as effectively as plastic, resulting in concentrated energy dissipation at the point of impact. It is preferred that the reinforcement member have a diameter of about {fraction (5/32)} inches for a five (5) gallon industrial pail having an outside curl diameter of about {fraction (5/16)} of an inch.

[0023] As shown in FIG. 7, the lower curl die 42 has an opening 90 for loading the reinforcement member 80 into the curved portion 48 of the lower curl die 42 prior to the pressing operation. A feeder mechanism (not shown) measures the reinforcement member being fed into the lower curl die and cuts the reinforcement member at the appropriate length so there is a minimal gap in the ends of the reinforcement member.

[0024] Thus as shown in FIGS. 11A and 11B an improved cylindrical pail is shown having a reinforced curl comprising a reinforcement member contained therein. The improved pail 106 is preferably made of steel and has a reinforcement member which may be made of plastic. It is preferred that the reinforcement member be made of a high density polyethylene. The pail may be used in combination with a lid having a plurality of lugs.

[0025] In another embodiment of the invention, the curl may be loaded with plastic or other suitable material comprising the following steps. First, the shell or cylinder is loaded into a press to partially form the curl so that a radial gap or opening remains. It is preferred that the curl be about 75% to 85% complete. Next, the shell is removed from the press and preferably rotated upside down.

[0026] Molten plastic or other suitable material is injected in the radial gap or opening from a nozzle in order to load the curl. After the plastic hardens or cures, the shell is put back in the press in order to completely form the curl.

[0027] While the invention has been shown and described with respect to specific embodiments thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art within the intended spirit and scope of the invention as set forth in the appended claims.

Claims

1. A metal pail comprising a curl reinforced with plastic.

2. The metal pail of claim 1 wherein the plastic is high density polyethylene.

3. A curl press machine for forming the curl of a pail and loading the curl with a reinforcement member, the machine comprising: an annular upper curl die having a curved section; an annular lower curl die having a curved section and being slidable from a first position to a second position; and said curved section of said lower curl die adapted for supporting said reinforcement member.

4. The curl press machine of claim 2 wherein said lower curl die radially translates.

5. The curl press machine of claim 2 wherein said lower curl die is formed of a plurality of curved segments.

6. The curl press machine of claim 5 wherein said plurality of annular segments have an extension slidably received within a radial groove of the upper curl die.

7. The curl press machine of claim 5 wherein said plurality of annular segments further comprise a tabular end received in a curved slot of an actuation ring.

8. The curl press machine of claim 7 wherein the actuator ring is rotatably mounted within the curl press machine.

9. The curl press machine of claim 7 wherein the curved slots are tangentially oriented.

10. A method for producing a reinforced curl of a pail comprising the following steps: partially forming a curl on the rim of a pail; injecting molten plastic within a gap formed between the end of the curl and the pail; allowing the molten plastic to cure; and closing the gap in the curl.

11. A method for producing a reinforced curl on a steel pail comprising the following steps: loading a curved section of a lower curl die with a reinforcement member; pressing a rim of a steel pail shell into a curved section of an upper die and down into an aligned curved section of a lower die around said reinforcement member.