1. Field of the Invention
The present invention relates, generally, to a molding system for the production of molded plastic articles, and more particularly, but not exclusively, the invention relates to a molding system for the production of container lids, and to a lid conveyor for use in the molding system for linking an injection molding machine with a lid packing station.
2. Background Information
A commonly used system for supporting a high-volume production of injection molded lids includes: a high cavitation multi-level stack mold operating in an injection molding machine that ejects lids formed therein directly onto a typical horizontal conveyor; the conveyor feeds the randomly oriented lids into a lid stacking system; the lid stacking system then orients, stacks, and bags the lids as required. The lid stacking system 20 is shown in
A fundamental shortcoming of such a lid molding system is the inherent cost and complexity of a machine designed in large part to reacquire a common lid orientation (i.e. the spin bowl, linear guide, and flipping device) in view of the potential to preserve the lid orientation directly from the injection mold. The system is known to experience periodic nesting and mis-orientation of lids that limits its efficiency or that of any downstream packaging operations.
A lid molding system wherein lid orientation is preserved from the injection mold to a lid stacking system is described in U.S. Pat. No. 5,037,597. As shown in
While this lid molding system provides a simple link between the injection mold 36 and the lid stacking station 20 that preserves the orientation of the lid 12, it does lack flexibility as the lid stacking system 20 must be positioned immediately adjacent the injection mold 36. This may be at the expense of an efficient or optimal workflow.
Furthermore, the injection molding machine requires an elevated supporting base that would invoke additional costs associated with a non-standard injection molding machine base, increased complexity for mold 36 installation and maintenance, the possibility of having to modify existing plant services and molding material connections, and the required height may simply be unavailable in many molding plants. In addition, the system may have difficulty in handling non-round lids because of their inability to roll through the chute extension 38.
U.S. Pat. Nos. 4,391,560, 3,741,366, and 3,938;675 all provide further examples of article molding systems that injection mold and stack plastic articles. Each of these systems requires some sort of preliminary operation to reacquire a common orientation of the articles prior to stacking.
Hence, there is a need for a simple and flexible lid molding system. More particularly, there is a need for a lid conveyor that is capable of maintaining a high productivity workflow coupling between a high-productivity injection mold and a lid stacking or other such downstream operation. Such a system would accommodate a conveyance distance and path that supports an optimal workflow, integrate standard equipment (i.e. injection molding machine and lid stacking), and accommodate lids of generally any size and shape.
The present invention provides a simple and flexible lid molding system that is generally capable of maintaining a high productivity workflow coupling between an injection molding system and a lid stacking operation, or other such downstream process.
The lid molding system includes a lid conveyor that cooperates with an in-mold part handling system. The lid conveyor furthermore accommodates lids of generally any size and shape, and is capable of conveying the lids along generally any path and through any distance.
In accordance with an aspect of the invention, a lid molding system includes an injection molding machine for the production of lids. The injection molding machine including an injection unit, an injection molding machine clamp unit with an injection mold mounted therein. The injection mold including an in-mold lid handling system mounted thereto that includes at least one guide chute. The lid molding system further includes a lid conveyor positioned beneath the injection molding machine clamp unit to align and engage with the at least one guide chute when the injection mold is in a closed position. The lid conveyor including means for lid guiding and means for lid driving wherein the lid conveyor, in use, receives lids from the guide chute of the in-mold lid handling system for conveying the lids to a downstream process in a generally vertical orientation.
The lid molding system may further include a lid packing station for the stacking and packaging of the lids, or may simply include a lid stacker for stacking the lids for subsequent handling.
In accordance with another aspect of the invention, a lid conveyor is provided that comprises a means for lid guiding that, in use, maintains a lid being guided therein in a generally vertical orientation, and a means for lid driving that is configured to engage, in use, a peripheral portion of the lid for transporting the lid therewith.
In a preferred embodiment, the means for lid driving is a provided by a re-circulating chain driven by a drive assembly wherein the chain includes a plurality of chain links connected by linking pins. Each of the chain links includes substantially parallel and spaced apart link members that are connected by a cylindrical spacer at an end thereof. The chain engages a peripheral portion of the lid in a space provided between the cylindrical spacers between adjacent chain links.
In accordance with an alternative embodiment of the invention, the chain may further include a plurality of engagement members attached thereto for engaging the peripheral portion of the lid.
In accordance with another aspect of the invention, a method for lid molding is provided that includes the steps of:
The method may further include the step of conveying the lids to a lid packing station, or to at least one lid stacker.
Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which:
Referring to FIG.(s) 3, 4, & 5, a lid molding system in accordance with a preferred embodiment of the present invention is shown. The molding system includes an injection molding machine clamp unit 34 with a 4-level lid stack mold 36 mounted therein between a stationary platen 50 and a moving platen 52. The injection molding machine, clamp unit 34, and mold 36 being operable as commonly known. The clamp unit is also shown as including a clamp assembly for operating the injection mold 36 between an open, closed, and clamped configuration, as generally described in U.S. Pat. No. Re 37,827. The injection mold 36 is configured for high-volume, efficient lid production and accordingly includes an in-mold lid handling means.
With reference to
The in-mold part handling system includes a plurality of side shuttles 66, each of which is operable to translate laterally across the molding faces 91, 92, 93, and 94 to retrieve a plurality of lids 12 from the rows of core molding inserts 65 and to thereafter transport the lids 12 to guide chutes 68. The step of retrieving the lids from the mold includes: positioning of the plurality of side shuttles 66 adjacent an exposed front face of the plurality of lids 12 that are still being held on the core molding inserts 65; and ejecting the plurality of lids 12 from the core molding inserts 65 onto a plurality of coupling members (not shown) that are arranged on the plurality of side shuttles, the ejection action being provided by a plurality of mold stripper rings (not shown) provided on the core plate assemblies. A guide chutes 68 is provided for each side shuttle 66. The guide chutes 68 are shown mounted to the hot runner section 62 adjacent the cavity plate assembly 63, and are oriented generally parallel to the row of molding cavities being serviced. Each side shuttle 66 is driven and guided by means provided on the hot runner section 62 of the injection mold 36. Each side shuttle is preferably driven through the use of a servo motor 64 and a transmission means (not shown). The detailed construction and operation of the side shuttle in-mold part handing system is provided in co-pending U.S. patent application Ser. No. 10/287,809. Of course, alternative in-mold part handling systems could be used, such as swing chutes described in U.S. Pat. No. 5,518,387. Of course, the number and locations of the shuttles may be varied depending upon the specific injection molding machine.
Four lanes of lid conveyors 71, 72, 73, 74 are shown with a dedicated lid conveyor lane servicing both guide chutes 68 of each molding face 91, 92, 93, 94. Each lane of lid conveyors 71, 72, 73, 74 are positioned beneath the injection molding machine clamp unit 34 to align and engage with the corresponding guide chutes 68 in a mold closed position. The construction and operation of the lid conveyors 71, 72, 73, 74 is described in more detail hereinafter.
In an alternative embodiment of the invention, a gate (not shown) positioned at the exit of the guide chutes 68 may be provided for sequencing the transfer of the lids 12 from each of the guide chutes 68 serviced by a lid conveyor, or each guide chute may be provided with a dedicated lid conveyor.
In operation, once the lids 12 have been transported into the guide chutes 68, and upon mold closing, the side shuttles 66 releases the lids 12. Thereafter, the lids 12 drop down the guide chutes 66, under the force of gravity, and into lid conveyors 71, 72, 73, and 74 in a substantially vertical orientation, that is on their peripheral edge. The lid conveyors 71, 72, 73, 74 maintain the lids in a generally vertical orientation during their transport to maintain proper engagement therewith. An advantage to conveying the lids 12 in a vertical orientation is that the lanes of lid conveyors 71, 72, 73, 74 can be spaced closely together which saves on the overall size of the molding system. Another advantage of the lid conveyors 71, 72, 73, 74 is its ability to transport the plurality of lids 12 along a path that includes corners and inclines and is therefore generally adaptable to any desired path. In particular, because the path of the lid conveyor 71, 72, 73, 74 can be inclined it can be used with an injection molding machine that provides only minimal clearance beneath the injection mold 36. As shown in
The lid packing station, shown in detail with reference to
The structure of the lid conveyor 71, 72, 73, 74 will now be described with reference to FIG.(s) 6, 7, 8 & 9. The basic structure of the lid conveyor 71, 72, 73, 74 is provided by a set of guides which maintain the vertical orientation of the molded lid 12, and a lid driving means for transporting the lid 12 along the-conveyor path, the lid 12 engaging the driving means about a peripheral portion thereof.
The lid driving means is preferably provided by a re-circulating chain 110 driven by a drive assembly (not shown). As shown in
The structure of a chain 110 provides an advantageous lid driving means given its three dimensional flexibility, albeit relatively limited in a direction that is generally perpendicular to the rotational axis of the cotter pin 114. In particular, varieties of chain are available that are capable of conforming to a conveyance path in substantially any direction. Of particular importance in the selection of a chain is to choose a chain that accommodates curvature in the conveyance path.
The cross-sectional structure of the lid conveyor 71, 72, 73, 74, as shown in
When the spacing between the cylindrical portions 118 of available chain 110 does not accommodate a suitable engagement with the peripheral portion of a lid 12, by virtue of the diameter or the shape of the lid 12, lid engagement members (not shown) could be attached to the chain 110 at a suitable pitch distance to engage the outer peripheral surface of the molded lid 12. Other possible lid driving means could include, for example, a cable or a belt with lid engagement members provided thereon.
An alternative lid molding system incorporating the lid conveyors 171, 172, 173, 174 in accordance with the present invention, is shown
All U.S. and foreign patent documents discussed above are hereby incorporated by reference into the Detailed Description of the Preferred Embodiment.
The individual components shown in outline or designated by blocks in the attached Drawings are all well-known in the molding arts, and their specific construction and operation are not critical to the operation or best mode for carrying out the invention.
While the present invention has been described with respect to what is presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.