The present invention relates to a molding apparatus, and more particularly, to a molding apparatus for making a continuous molded article.
Foam-in-place packaging is a highly useful technique for on-demand protection of packaged products. In its most basic form, foam-in-place packaging comprises injecting foamable compositions from a dispenser into a container that holds a product to be cushioned. Typically, the product is wrapped in plastic to keep it from direct contact with the rising (expanding) foam. As the foam rises, it expands into the remaining space between the product and its container (e.g. a box formed of corrugated paperboard), thus forming a custom cushion for the product.
A common foaming composition is formed by mixing an isocyanate compound with a hydroxyl-containing material, such as a polyol (i.e., a compound that contains multiple hydroxyl groups), typically in the presence of water and a catalyst. The isocyanate and polyol precursors react to form polyurethane. At the same time, the water reacts with the isocyanate compound to produce carbon dioxide. The carbon dioxide causes the polyurethane to expand into a foamed cellular structure, i.e., a polyurethane foam, which serves to protect the packaged product.
In other types of foam-in-place packaging, the foam precursors are injected into a plastic bag, which is then dropped into a container holding the product to be cushioned. The rising foam again tends to expand into the available space, but does so inside the bag. Because the bags are formed of flexible plastic, they form individual custom foam cushions for the packaged products. In several techniques, a specific apparatus is used to make the bag from plastic film while concurrently injecting it with foam. Exemplary devices for making such ‘foam-in-bag’ packaging cushions are assigned to the assignee of the present invention, and are illustrated, for example, in U.S. Pat. Nos. 5,027,583, 5,376,219, and 6,003,288, the contents of each of which are hereby incorporated entirely herein by reference thereto.
In other packaging applications, similar or identical products are repeatedly placed in similar or identical orientations in similar or identically sized containers. Such circumstances increase the need for more standard packaging elements that have a consistent size and shape.
U.S. Pat. Nos. 5,776,510, 6,386,850, and 7,607,911, the contents of each of which are hereby incorporated entirely herein by reference thereto, disclose methods and apparatus for automatically molding defined three-dimensional polyurethane foam cushions utilizing the foam-in-bag techniques discussed above, but with the added feature of placing a bag containing a foamable composition in a mold as the composition begins to form foam, and maintaining the bag in the mold until the composition has finished forming a foam cushion in a shape conforming to the shape of the mold. These inventions have beneficially combined the advantages of on-demand, foam-in-bag packaging with the ability to produce standard packaging cushions having a consistent size and shape.
While the forgoing molding techniques have been highly successful, the inventors hereof have determined that for high-volume molding applications, a molding apparatus capable of making a continuous molded article, e.g., which may be separated into a series of foam-in-bag molded cushions, would be highly beneficial. One approach for making a continuous molded, foamed article, or a series thereof, is to employ a pair of spaced-apart molding assemblies, e.g., comprising a pair of counter-rotating endless belts, which drive a series of movable mold segments that align and converge to form a movable mold with a dynamic mold cavity therein. A dispenser of a moldable, expandable composition, e.g., a polyurethane foam composition as described above, may further be employed to dispense the composition into the dynamic mold-cavity on a continuous basis, with a film-feeding mechanism also employed to continuously feed a center-folded film, or a pair of films, into the dynamic mold-cavity, such that the film is interposed between the moldable composition and the molding assemblies.
A significant difficulty with the foregoing approach is that the dynamic nature of the process makes it difficult to maintain a consistent mold-cavity shape. In order for the dynamic mold-cavity to form a desired mold shape, the movable mold segments must maintain a predetermined alignment as they are conveyed along a path in each molding assembly. However, after the initial introduction of the expandable, e.g., foamable, composition into the dynamic mold-cavity, the composition expands as it hardens into a foam. Such expansion and hardening occurs as the composition is conveyed within the dynamic mold-cavity, the shape of which must be maintained by the moving mold segments as the expanding foam exerts a force against such segments, due to physical contact therebetween. The magnitude of the force increases as the foam expands to fully fill the cavity, due to the increased area of contact in the mold-cavity between the expanding foam and the moving mold segments.
As may be appreciated, certain directional components of the expanding foam-force, e.g., in the direction along which the segments are being conveyed, has a tendency to cause the mold segments to deviate from their predetermined alignment, i.e., to push the mold segments out of alignment during their conveyance along the moving mold path. This tendency exists because of the dynamic nature of the continuous molding process—since the mold segments are movable, they can be moved not only in the direction of conveyance, which is desired, but can also be moved out of their mold-shape alignment, which is highly undesirable because such misalignment results in a poorly-formed molded article at best, and a catastrophic failure of the molding assembly at worst.
Another difficulty associated with the foregoing continuous molding process concerns proper alignment of both the foam dispensing device and sealing equipment used to seal the foam inside the film, vis-à-vis the dynamic mold-cavity. By changing the mold segments, the shape of the mold-cavity can be changed to produce molded articles having a desired shape. Such changes in the mold shape often necessitate the ability to inject the foam at different positions, e.g., to coincide with the widest or deepest part of the mold-cavity, and/or to seal the film at variable positions.
A further difficulty of continuous molding pertains to the release of the mold segments from the molded article at the end of the dynamic mold-cavity. With an endless-belt type molding assembly, for example, the mold segments diverge in a rotational fashion from the mold-cavity at a rotary guide member. Depending on the shape of the molded article, such release can be difficult to accomplish without causing damage to the molded article.
Accordingly, there remains a need in the art for improvements in the machines and processes for making a continuous series of molded articles, which overcome the foregoing difficulties.
Those needs are met by the present invention, which, in one aspect, provides a molding apparatus for making a continuous molded article, comprising:
a. a pair of spaced-apart molding assemblies, which cooperatively generate a movable mold having a dynamic mold-cavity therein, each of the molding assemblies comprising:
b. a dispenser for dispensing a moldable, expandable material into the dynamic mold-cavity.
A further aspect of the invention is directed to a method for making a continuous molded article, comprising:
a. providing a pair of molding assemblies, each of which comprises a series of movable mold segments, which are adapted to fit together to form a portion of a dynamic mold-cavity;
b. conveying the movable mold segments of each of the molding assemblies along a path and with a predetermined alignment to continuously form each of the respective portions of the dynamic mold-cavity;
c. converging the mold-cavity portions of each of the molding assemblies as the mold-cavity portions are formed, thereby generating a moving mold with the dynamic mold-cavity therein;
d. dispensing a moldable, expandable material into the dynamic mold-cavity, the material expanding within the dynamic mold-cavity and exerting a force on the mold segments as they are conveyed along the path, wherein one or more directional components of the force have a tendency to cause the mold segments to deviate from the predetermined alignment; and
e. responding to any the deviations of the mold segments from the predetermined alignment by urging the mold segments to return towards the predetermined alignment.
Another aspect of the invention is directed to a molding apparatus for making a continuous molded article, comprising:
a. a pair of spaced-apart molding assemblies, which cooperatively generate a movable mold having a dynamic mold-cavity therein, each of the molding assemblies comprising:
b. a dispenser for dispensing a moldable, expandable material into the dynamic mold-cavity, the dispenser being movably positionable with respect to the molding assemblies.
Yet another aspect of the invention is directed to a molding apparatus for making a continuous molded article, comprising:
a. a pair of spaced-apart molding assemblies, which cooperatively generate a movable mold having a dynamic mold-cavity therein, each of the molding assemblies comprising:
b. a dispenser for dispensing a moldable, expandable material into the dynamic mold-cavity.
These and other aspects and features of the invention may be better understood with reference to the following description and accompanying drawings.
Referring to
Each of the molding assemblies 16a, b comprise a series of movable mold segments 22a, b, respectively, which are adapted to fit together to form a portion, e.g., half, of the dynamic mold-cavity 20. Each of the molding assemblies 16a, b further includes a drive mechanism 24a, b, respectively, for conveying the respective mold segments 22a, b along a path as shown. Each of the mold segments 22a, b are affixed to a respective one of the drive mechanisms 24a, b with a predetermined alignment to continuously form the respective portion of dynamic mold-cavity 20 as the mold segments 22a, b are conveyed along their respective paths.
Such paths can take any desired form, e.g., linear, such that they operate in reciprocal fashion. In the presently-illustrated embodiment, such paths are circuitous. Thus, the drive mechanisms 24a, b for each of the respective molding assemblies 16a, b may each comprise an endless belt driven about a circuit. For molding assembly 16a, such circuit may be defined by a pair of spaced-apart, rotary end-members 26a, b, between which and around which the endless-belt-type drive mechanism 24a is driven about its circuitous path, as shown in
The endless-belt-type drive mechanisms 24a, b may include a continuous chain, belt, cable, etc., as the means by which the components of each drive mechanism are linked together and driven along their circuitous path. In the illustrated embodiment, chains are used for this purpose. Thus, as shown in
Suitable drive means 40a, b, shown in
With continuing reference to
One or more fastener devices 52, e.g., 52a and 52b, may be affixed to each of the slats 42a, b for both respective molding assemblies 16a, b. Such fastener devices 52 may be adapted to secure one or more of the mold segments 22a, b to each of the respective slats 42a, b, as shown perhaps most clearly in
Referring now to
Moldable, expandable material 58 dispensed by dispenser 56 may be a foamable polyurethane composition, e.g., from a reactive mixture of a polyol, supplied to the dispenser by hose 60a, and an isocyanate, supplied to the dispenser by hose 60b. Apparatus 10 may also include a film-feeding mechanism 62 for interposing one or more films, e.g., a single, center-folded film 64 as illustrated, between the foamable composition 58 and the molding assemblies 16a, b. Such arrangement is particularly advantageous when material 58 is a foamable polyurethane composition, which tends to be rather sticky. The film 64 prevents unwanted adhesion between the material 58 and mold segments 22. The film 64 may be supplied, e.g., as a center-folded film as illustrated or as a pair of juxtaposed films, from a roll 66 as shown. The film-feeding mechanism 62 may include at least one sealing device 68 for sealing the film(s), e.g., a longitudinal edge-seal device. When film 64 is a center-folded film with one open longitudinal edge 70 as shown, only one edge-seal device 68 is needed to close the open longitudinal edge 70, e.g., with a continuous longitudinal seal 72, beginning at a point just downstream of dispenser 56. As shown, this arrangement allows dispenser 56 to be inserted into the center-folded film 64 as it dispenses the moldable material 58 therein. Sealing device 68 may include a pair of counter-rotating rollers as shown, which form longitudinal seal 72 therebetween, e.g., via a suitable heat-seal unit (not shown), such as a heated wire or the like. The counter-rotating rollers can also serve the function of pulling film 64 from roll 66, and feeding the same into entrance 30 of moving mold 18, wherein the counter-rotating molding assemblies 16a, b then take over the function of pulling the film through the moving mold 18. Further details concerning the dispenser 56, film-feed mechanism 62, and sealing device 68, as well as many alternative arrangements, are described in the above-incorporated patents in the Background section hereof, and any such dispensing/film-feeding arrangements may be employed with molding apparatus 10. Unlike such arrangements, however, the dispensing/film-feeding arrangement employed with the present invention need not include a transverse sealing/severing device for making seals and cuts across the width of the film, which otherwise form discrete bags in which the foamable composition is contained. Instead, molding apparatus 10 makes a continuous molded article 12, with the film 64 and moldable material 58 being continuously fed into the moving mold 18 and dynamic mold cavity 20 thereof, such that the molded article 12 continuously emerges from the cavity 20 at exit 32, as shown in
Thus, a method for making a continuous molded article 12 includes providing molding assemblies 16a, b, each of which comprises a respective series of movable mold segments 22a, b, which are adapted to fit together to form a portion, e.g., half, of dynamic mold-cavity 20. The movable mold segments 22a, b of each of the molding assemblies 16a, b are conveyed along the, e.g., circuitous, path shown in
This is perhaps best shown in
As the moldable, expandable material 58 is dispensed into dynamic mold-cavity 20, it begins to expand within the dynamic mold-cavity, and continues to expand, at the same time that the mold-cavity portions 74a, b of each of the molding assemblies 16a, b converge, as shown progressively in
When corrected in accordance the present invention (discussed below), however, a continuous molded article 12 with a desired shape can be continuously produced, i.e., formed and hardened into a permanent molded-shape within dynamic mold-cavity 20 during the conveyance of such article 12 between the entrance and exit points 30, 32 of moving mold 18, part of the progression of which is shown in
The continuous molded article 12 can have any desired shape and can be produced in continuous fashion as described above. The final form that the molded article 12 will assume will depend on the predetermined size, shape, and configuration of, as well as the spacing between, the mold-cavity portions 74a, b. In the illustrated embodiment, the continuous molded article 12 has a generally trapezoidal cross-sectional shape, with bendable hinge-regions 76 and separation-regions 78 (
Many other shapes and configurations are, of course, possible, with the continuous molded article 12 merely being an illustrated example. For instance, while wedge-shaped protrusions 80 are adapted to form 90-degree bend regions 76, such protrusions could also be adapted to form 60-degree bend regions, resulting in the hexagonal-shaped configuration shown in
As noted above, the expansion of material 58 within dynamic mold-cavity 20, as the volume thereof decreases and then reaches a fixed, final volume (FIGS. 3 and 3A-3D), results in various forces being exerted on the mold segments 22a, b as they are conveyed along the path of the moving mold 18 between the entrance and exit points 30, 32 thereof. Such forces are generally directed outwards from expanding material 58 and against the mold-cavity portions 74a, b of the dynamic mold-cavity 20.
In accordance with the present invention, each of the molding assemblies 16a, b include one or more alignment-correction devices 94, which urge the respective mold segments 22a, b towards their predetermined alignment in the event that the mold segments deviate therefrom during their conveyance in direction 34 along the path of the moving mold 18. In other words, the alignment-correction devices 94 provide the function of responding to any deviations of the mold segments 22a, b from their predetermined alignment, by urging the mold segments to return towards such predetermined alignment when/as they deviate therefrom. In this manner, the integrity of the dynamic mold-cavity 20 is preserved, despite the dynamic nature of the mold and the disruptive tendency of forces 88a, b from expanding material 58 being molded therein.
With continuing reference to
Additional reference will now be made to
Thus, for example, pivotal movement of one of alignment-correction device 94b in a first direction 102 urges pivotal movement of at least one adjacent alignment-correction device, e.g., device 94a, in a second direction 104. As may be seen, first direction 102 is counter-clockwise while second direction 104 is clockwise. Thus, as device 94b begins to rotate about pivot point 100 in first direction 102, i.e., due to force 88b acting on the mold segment 22b associated with device 94b, the concave portion 98 of device 94b engages the convex portion 96 of device 94a, causing it to pivot about its pivot point 100 in second direction 104. The relative shapes and positioning of the concave portion 98 of device 94b and the convex portion 96 of device 94a causes device 94a to pivot in second direction 104, which is against the direction of pivot of device 94b, i.e., first direction 102. In this example, the upper part 99 of concave portion 98 of device 94b contacts the upper part 97 of the convex portion 96 of device 94a, as device 94b pivots counter-clockwise in first direction 102. This exerts a downward, clockwise force upon the convex portion 96 of device 94a, which thus pivots, or at least attempts to pivot, about its pivot point 100 in second, clockwise direction 104. Such counter-pivoting of adjacent device 94a in second direction 104 thus resists, e.g., urges against, the undesirable pivoting of device 94b in first direction 102 due to force 88b. In this manner, alignment-correction device 94a thus urges at least the mold segment 22b associated therewith and with device 94b towards their predetermined alignment (
With continuing reference to
Due to inertia, device 94c and the mold segment 22b associated therewith will resist such movement in second direction 104, which thus serves to further urge against the undesirable pivot 102 of device 94b (i.e., in addition to the counter-urging of device 94a) due to force 88b that, in this example, is acting on the mold segment 22b associated with device 94b in a localized manner due to expansion of expandable, moldable material 58 in dynamic mold-cavity 20.
As further indicated in
Accordingly, in the illustrated embodiment, it may be seen that the alignment-correction devices 94 thus function in a reactive, cooperative, and self-correcting manner to continuously urge the mold segments to return to their predetermined and desired alignment, as shown
As noted above, one or more of the alignment-correction devices 94 may be associated with each of the mold segments 22a, b. Thus, for example, one or more of the alignment-correction devices 94 may be attached to each of the slats 42a, b. For instance, as illustrated in the embodiment shown in
Apparatus 10 may further include a frame 112 for supporting the molding assemblies 16a, b (
Referring now to
Pivotally affixing a mold segment to drive mechanism 24a and/or b may be advantageous when the mold-half surface provided by a particular mold segment, or a contiguous group thereof, has a deep and/or steep profile 130 as illustrated in mold segment 22c, such that the release of the mold segment from the resultant continuous molded article would be difficult at exit 32 of moving mold 18. This is illustrated in
However, the inventors hereof have found that by including pivotal member 118, the mold segment 22c is able to release substantially vertically from molded article 126 at the point of tangential transition, as indicated by arrow 134, so that the protrusions 128 and deep-profile 130 separate in a substantially linear fashion at such transition point, whereby no physical hindrance occurs and a clean release is possible. After release, the mold segments 22c can pivot forward and assume their normal/predetermined alignment on the drive mechanism 24b, with base elements 120a, b being in contact with one another, until the next time that such mold segment reaches the exit point 32 of the moving mold 18 to again release from the molded article 126. In this regard, a magnet or the like may be employed on one of the contacting surfaces of the base elements 120a, b to facilitate holding the base elements together during their transit about the circuit of the molding assembly 16b.
Referring now to
In many instances, it is beneficial to mount dispenser 56 such that it is movably positionable, e.g., pivotally and/or translationally, with respect to molding assemblies 16a, b. Thus, as shown with respect to alternative apparatus 10′ in
The dispenser 56 can also, or instead, be made translationally movable with respect to molding assemblies 16a, b, by mounting it on slide bar 142 via slide mount 144. This allows the dispenser to be positioned at any desired location across the width of the molding assemblies 16a, b, i.e., anywhere between frame members 112a and 112b as shown, by sliding the dispenser along slide bar 142 in either of the directions indicated by bi-directional arrow 146. When mold segments 22 are changed, the shape of the dynamic mold-cavity 22 defined therebetween will be changed, and thus the ability to inject the foam at different positions, e.g., to coincide with the widest or deepest part of the mold-cavity, by simply sliding the dispenser 56 along the slide bar 142 to the optimal location, is a highly beneficial feature to the practice of making continuous molded articles in accordance with the present invention.
Similarly, when mold segments 22 are changed, the width of film 64 can change to suit the particular size/shape of the resultant dynamic mold-cavity 20. Thus, being able to seal the film at variable positions across the width of the molding assemblies 16a, b would also be highly beneficial. This may be accomplished in accordance with the present invention by mounting sealing device 68 such that it is movably positionable with respect to the molding assemblies 16a, b, e.g., by mounting it to slide bar 148 as shown, which allows it to be positioned at any desired location across the width of the molding assemblies 16a, b, i.e., anywhere between frame members 112a and 112b as shown, by sliding the sealing device 68 along slide bar 148 in either of the directions indicated by bi-directional arrow 150.
With reference to
The foregoing description of preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention.
Number | Name | Date | Kind |
---|---|---|---|
3142864 | Pelley | Aug 1964 | A |
3300944 | Thesing | Jan 1967 | A |
3485347 | McGill et al. | Dec 1969 | A |
3566448 | Ernst | Mar 1971 | A |
3736081 | Yovanovich | May 1973 | A |
3837774 | Ross et al. | Sep 1974 | A |
4128369 | Kemerer et al. | Dec 1978 | A |
4149840 | Tippmann | Apr 1979 | A |
4207279 | Boon | Jun 1980 | A |
4265608 | Tunador et al. | May 1981 | A |
4981427 | Prignitz | Jan 1991 | A |
5027583 | Chelak | Jul 1991 | A |
5167781 | Kemerer et al. | Dec 1992 | A |
5244618 | Kemerer et al. | Sep 1993 | A |
5330341 | Kemerer et al. | Jul 1994 | A |
5376219 | Sperry et al. | Dec 1994 | A |
5458477 | Kemerer et al. | Oct 1995 | A |
5505599 | Kemerer et al. | Apr 1996 | A |
5700495 | Kemerer et al. | Dec 1997 | A |
5756131 | Suh | May 1998 | A |
5776510 | Reichental et al. | Jul 1998 | A |
6003288 | Sperry et al. | Dec 1999 | A |
6085627 | Denney | Jul 2000 | A |
6178725 | Sperry et al. | Jan 2001 | B1 |
6386850 | Salerno et al. | May 2002 | B1 |
6472638 | Sperry et al. | Oct 2002 | B1 |
7607911 | Sperry et al. | Oct 2009 | B2 |
20050287238 | Taylor | Dec 2005 | A1 |
20060071369 | Butteriss | Apr 2006 | A1 |
20060186572 | Brown | Aug 2006 | A1 |
20070052128 | Taylor | Mar 2007 | A1 |
20070252298 | Sperry et al. | Nov 2007 | A1 |
20100201014 | Taylor | Aug 2010 | A1 |
Number | Date | Country | |
---|---|---|---|
20130214445 A1 | Aug 2013 | US |