SPIN WELDED LID AND CONTAINER

Abstract: A container (10) and lid (11) have cooperating tongue (21) and groove portions (14) for providing a fused connection during a spin welding operation. The combination is provided with a plurality of debris traps (66, 68) for accomodating molten material to preclude contamination of the container contents. The lid (11) includes a flange or skirt portion (24) having an end surface thereof for engaging a rim (55) of the container (10) to provide an interfaced fused surface.

Description: SPIN WELDED LID AND CONTAINER BACKGROUND OF THE INVENTION This invention relates to new and improved containers for containing and protecting products and more particularly relates to improved structural features in the container body and also in an end closure for closing and sealing the container body. The invention further relates to methods and apparatus for locating the end closure onto the container and spin welding the two components together to provide an hermetically sealed container suitable for a plethora of products including, but not limited to, containers for food and beverages suitable for human and animal consumption, as well as any other dry, moist or liquid product that needs to be protected from the elements. SUMMARY OF THE INVENTION The invention relates to improvements in containers 10 and lids 11 for closing the containers to provide improved sealing characteristics as well as improved handling characteristics of the separate constituents incident to placing a lid onto the open end of a container, and relatively spinning the lid and container under pressure to generate sufficient heat to cause partial melting of thermoplastic material used to form the container and/or the lid structure ^ BRTEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged, vertical, sectional view through a portion of a container body 10 and a lid 11. FIG. 2 is an elevational view of a container and lid thereon and having an encircled portion corresponding to the enlarged view of FIG. 1. FIG. 3 is a plan view of the container and lid shown in FIG. 2. FIG. 4 is an enlarged, fragmentary, sectional view similar to FIG. 1 and shows the parts prior to force being applied during a spinning, closing operation. FIG. 5. is a sketch similar to FIG. 4 and shows migration of plastic material from the lid and container following the spin welding process. FIG. 6 is a fragmentary, vertical sectional view of a nest 60 for receiving and holding a container body during the closing operation. FIG. 7 is a bottom view of a chuck 70 which engages the lid during the spinning operation. FIG. 8 is a fragmentary, elevational view of a chuck 70 including a series of knives 80 for engaging a rim of a container lid. FIG. 9 is an enlarged view of a knife 80 shown in FIG.8. FIG. 10 is an elevational view of one knife 90 for engaging the underside of a container flange 92 during spinning of the lid onto the container. FIG. 11 is a fragmentary showing of a side view of a knife 90 of FIG. 10. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. l, it will be seen that a tongue and groove relationship causes interference between the wall 12 of a groove 14 in the lid 11 with a top 18 and outside wall portion 20 of the tongue portion 21 on the top edge of the container body. Lid 11 includes a hinged pull tab 27 connected to end panel 17, as is shown in FIG. 3, to aid in removal of panel 17 from lid frame portion 16. The lid 11 is held in a spinning chuck 70 (see FIG. 8) so that the outer wall, or skirt portion 31, of the lid frame portion 16 is cammed radially inwardly into contact with the outer portion of the tongue 20. Rotation of the lid 11, or the container 10, generates heat for melting, and then fusing, of the lid to the top portion of the container body. The spinning process is, generally speaking, old in the art but both the container bowl and the lid are considered to be novel improvements over the prior art. The lid 11 is designed to be downwardly loaded at point 22 as shown in FIG. 1 to engage the top of the tongue at 18 before the bottom of the skirt or leg of the lid frame meets the container flange at point 24. The underside of the container 10 or bowl flange 92 is supported by a nest 60 (shown in FIGS. 6 and 8), the nest being a part of the Spin Welding machine (not shown). The result is that the leg or skirt portion of the lid frame 16 is rotated radially inwardly against the side of the tongue 21, heat is generated during the spinning operation and molten plastic flows from the top portion 18 of the tongue 21, and the inside surface of the groove 14, and flows in the manner shown in FIG. 5. When the spinning is completed, the molten material cools, solidifies and creates a bond between the lid and the container. As is shown in FIGS. 6-11, the addition of knives 80 and 90, in both the holding chuck 70 and the nest 60 holding the container 10 hold the container stationary within the nest and hold the lid stationary relative to the spinning chuck 70 for rotation therewith relative to the container 10. Therefore, the spinning energy is transferred to the lid 11 and container 10 interface, dissipated as heat, and melts the plastic interface thus creating a bond between the two components. A multiple number of "debris legs" 42, 52, 62 and 65, as best shown in FIGS. 4 and 5, on the top side of the container 10 and the underside of the lid 11, create debris A series of radial ribs 15 on the top inside edge of the frame portion 16 of the lid 11 (see FIGS. 1 and 3) facilitates slippage of the lids during high speed feeding of sequential lids by keeping the leg on an uppermost lid from hanging up on the adjacent end panel 17 of the adjacent lid. A series of internal radial ribs 21, as best shown in FIG. 1, extend radially within the debris trap 66 and during rotation of the lid break up debris to avoid large globs of debris from forming and overcoming the debris traps. The end panel 17, which is attached at its periphery 19 to the frame portion 16 of the lid 11, is scored with a circumferential score line 31 on the underside thereof, as is best shown in FIG. 5. This score 31 causes the end panel 17 to assume a convex mode relative to the container 10 for reducing head space in the closed and sealed container. Known types of oxygen absorbers are specifically added to the material of the frame of the lid to reduce oxygen permeation when the container is to contain oxygen sensitive food products and the like. Oxygen absorbers, in combination with high barrier polymers 61, such as EVOH, in the lid stock provides better protection to oxygen than metal ends. The foregoing descriptions, in combination with the showings in the accompanying drawings, define a preferred embodiment of the invention which is to be limited only by the following claimed subject matter.

Claims: CLAIMS 1. A container lid formed of thermoplastic material and including a peripheral flange portion having an upwardly extending groove on an underside thereof for receiving a tongue portion of a complementary container, said lid including a plurality of downwardly extending legs for forming debris traps for trapping molten material incident to a spin welding process for securing said lid to the underlying container. 2. A container formed of thermoplastic material and having an upper peripheral flange including a tongue portion for extending into a groove of a complementary container lid, at least one upwardly extending debris leg cooperating with said tongue for forming at least one debris trap for trapping molten material incident to a spin welding process for securing said container to an overlying container lid. 3. The combination of a container lid formed of thermoplastic material and including a peripheral flange portion having an upwardly extending groove on an underside thereof for receiving a tongue portion of a complementary container, said lid including a plurality of downwardly extending legs for forming debris traps for trapping molten material incident to a spin welding process for securing said lid to the underlying container, and a container formed of thermoplastic material and having an upper peripheral flange including a tongue portion for extending into a groove of a complementary container lid, at least one upwardly extending debris leg cooperating with said tongue for forming at least one debris trap for trapping molten material incident to a spin welding process for securing said container to an overlying container lid. 4. A container lid as defined in claim 1 including a downwardly extending peripheral skirt having a lowermost engaging surface for contacting the flange of an underlying container, and the skirt providing meltable material for fusing and connecting said lid to said container. 5. A container lid as defined ini claim 1 wherein said lid includes a raially extending rib for extending into a debris trap for breaking up molten debris during a spin welding operation.

Applicants: SILGAN CONTAINERS CORP, SILGAN CONTAINERS CORPORATION
Application year: 2001
Main classification: B65D41
IPC codes: B29C65, B65D6, B65D8, B65D77