Patent Application
20200269487
The present invention relates to systems and methods for forming parts, and more particularly, embodiments concern a system and method for stamp- or mold-forming a blank of material into a part using a moveable heater to heat the blank in a pre-aligned position and a recoil alignment mechanism to maintain the alignment of the heated blank during the forming process.
When stamp- or mold-forming parts, a blank of consolidated composite thermoplastic or other formable material is placed in a frame and restrained using spring clamps, the frame is transferred to an oven, and the blank is heated to its melt point to ensure the melting of the polymer matrix throughout the entire blank. The frame is then transferred to and aligned within a press and the part is formed under pressure to a desired shape by matched-mold tooling. The maximum allowable delay between removing the blank from the oven and forming the blank under pressure is five seconds or less before the blank rapidly cools to below its melt point. Thus, the blank must be removed from the oven, moved to the press, properly aligned within the press frame, and very quickly formed before the blank cools below the forming temperature (e.g., within five seconds for some materials). This is achievable for small parts (i.e., parts having dimensions of less than three feet) with uniform thicknesses, but has not been achievable for larger parts or parts with more complex geometries (e.g., buried ply drops). In particular, parts with increased size and/or complexity require complex part restraint and motion control systems in order to accomplish the move in time.
One problem arises with moving the large and/or complex part from the oven to the press both quickly and accurately. Spring clamps used in the frame to restrain the blank can cause misalignment and motion in the blank under high acceleration forces associated with the rapid transfer motion between processing steps. Another problem results from sagging or other flexing of the melted part as it is transferred from the oven to the press, which can change the alignment. Yet another problem occurs with the frame which holds the heated blank in place while a moving side of the press pushes the part the final distance and stamps it between dies under pressure without moving the frame. Misalignment and deformation can result when the moving die, which may be, for example, 400 degrees F., contacts the blank, which may be, for example, between 500 and 800 degrees F., and pushes the blank against the static die. This temperature difference and physical pushing can misalign the blank prior to or during actual forming. Furthermore, larger and/or more complex parts may experience uncontrolled deformation (e.g., stretching) during closure of the mold due to the static frame with springs having restrained lateral motion (i.e., the direction of the movement of the press), which prevents the heated blank from maintaining alignment with the tooling until it is fully formed under pressure. These issues outlined for the current production process create a potential (increasing with part size and complexity) for misalignment and premature cooling of the part prior to forming, which can adversely affect the dimensions of and introduce defects into the final part.
This background discussion is intended to provide information related to the present invention which is not necessarily prior art.
Embodiments of the present invention address the above-described and other problems and limitations in the prior art by providing a system and method for stamp- or mold-forming a blank of material into a part using a moveable heater to heat the blank in a pre-aligned position and a recoil alignment mechanism to maintain the alignment of the heated blank during press closure in the forming process.
In a first embodiment of the present invention, a system is provided for heating and aligning a blank of a material in order to form the blank into a part in a press including first and second dies. Broadly, the system may comprise a frame, a heater element, and an alignment mechanism. The frame may be holding the blank in an aligned position between the first and second dies. The heater element may be between a first position within the press to heat the blank in the aligned position to a forming temperature, and a second position to allow the first and second dies to form the blank into the part. The alignment mechanism may be maintaining the blank in the aligned positioned between the first and second dies as the first and second dies are brought together to form the blank into the part. The alignment mechanism may comprise a rail and a collapsible member. The rail may extend between the first and second dies and through the frame and allow the first die and the frame to slide between a first position in which the first and second dies and the frame are spaced apart and a second position in which the first and second dies and the frame are in physical contact. The collapsible member may extend between the first die and the frame and space the frame apart from the first die, push the frame toward the second die as the first die moves toward the second die, and collapse when the frame contacts the second die to allow the first and second dies to contact the blank and form the blank into the part.
In a second embodiment of the present invention, a method may be provided for heating and aligning a blank of a material in order to form the blank into a part in a press including first and second dies. Broadly, the method may comprise the following steps. The blank may be held in a frame in an aligned position between the first and second dies. A heater element may advance to a first position within the press to heat the blank in the aligned position to a forming temperature, and the heater element may withdraw to a second position to allow the first and second dies to form the blank into the part. The blank may be maintained in the aligned positioned between the first and second dies as the first and second dies are brought together to form the blank into the part. In more detail, the frame may be spaced apart from the first die using a collapsible member extending between the first die and the frame, wherein the first die and the frame are slidingly mounted on a rail extending between the first and second dies and through the frame. The first die may be moved along the rail toward the second die, wherein the collapsible member may push the frame along the rail toward the second die as the first die moves along the rail toward the second die. The collapsible member may collapse when the frame contacts the second die to allow the first and second dies to contact the blank and form the blank into the part.
Various implementations of the foregoing embodiments may include any one or more of the following features. The blank may have a dimension of at least five feet and/or an area of at least twenty-five square feet. The material may comprise a plurality of reinforcing fibers and a thermoplastic resin. The material may comprise a metal. The heater element using infrared or convection heating to heat the blank to the forming temperature. A first heater element may advance from a first direction and a second heater element may advance from a second direction to the first position, and the system may further comprise an indexing mechanism aligning the first and second heater elements at the first position. The collapsible member may comprise a spring and/or two or more nested elements. The system may further comprise a laser alignment system facilitating aligning the blank in the aligned position in the frame.
This summary is not intended to identify essential features of the present invention, and is not intended to be used to limit the scope of the claims. These and other aspects of the present invention are described below in greater detail.
Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:
The figures are not intended to limit the present invention to the specific embodiments they depict. The drawings are not necessarily to scale.
The following detailed description of embodiments of the invention references the accompanying figures. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those with ordinary skill in the art to practice the invention. Other embodiments may be utilized and changes may be made without departing from the scope of the claims. The following description is, therefore, not limiting. The scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.
In this description, references to “one embodiment,” “an embodiment,” or “embodiments” mean that the feature or features referred to are included in at least one embodiment of the invention. Separate references to “one embodiment,” “an embodiment,” or “embodiments” in this description do not necessarily refer to the same embodiment and are not mutually exclusive unless so stated. Specifically, a feature, component, action, step, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, particular implementations of the present invention can include a variety of combinations and/or integrations of the embodiments described herein.
Broadly characterized, embodiments of the present invention provide a system and method for stamp- or mold-forming a blank of material into a part using a moveable heater to heat the blank in a pre-aligned position and a recoil alignment mechanism to maintain the alignment of the heated blank during the forming process. More particularly, embodiments provide improvements in the field of large-scale stamp- or mold-forming large and/or complex parts of thermoplastic, metal, high-temperature composite, or other formable material by providing a moveable heater which heats the pre-aligned blank in situ in the press and a recoil alignment mechanism which maintains the alignment of the blank throughout the forming process. These improvements advantageously allow for more accurately, quickly, and repeatably forming larger and/or complex parts with fewer defects than is currently achievable using prior art technology.
Embodiments may include a moveable heater configured to advance to a first position, heat a blank of material which is already positioned and properly aligned within a press, and then quickly withdraw to a second position so that the press can close and the heated blank can be formed into the part. Broadly, in one implementation the heater may be configured to move (by, e.g., mechanical, hydraulic, or pneumatic force over a rail or other structure) into physical proximity with a blank which is already pre-aligned in the press, heat the blank to its melt or other forming temperature, and then quickly withdraw so that the heated blank can be formed under pressure between dies.
In more detail, the blank of (e.g., thermoplastic composite) material may be positioned within the press and properly aligned with the dies. Once the blank is properly aligned, one or more moveable heater elements may be advanced into position and activated to heat the blank positioned within the press to the desired temperature. Once the desired temperature has been reached, the one or more moveable heater elements may be withdrawn. Once the one or more moveable heater elements have been withdrawn, the press may be activated such that the dies are brought together on or around the heated blank to form the blank into the part before the blank cools below a minimum temperature.
This advantageously allows for pre-positioning and pre-aligning the blank prior to heating, which reduces or eliminates prior art problems arising from having to quickly transfer the heated blank and then quickly yet accurately align the transferred blank before it cools too much for forming, and also increases the overall efficiency of the process and allows for increased throughput. In particular, embodiments address problems and limitations in the prior art by providing more time to ensure an accurate alignment because the part is aligned prior to heating; the moveable heater can be withdrawn faster than a large part can be moved between a fixed oven and the press; and because the heater can be built into the press system, the need for a large track system for moving large blanks is reduced or eliminated. Additionally, the excess movement and misalignment caused by acceleration forces on the blank secured in the frame by spring clamps is negated through shifting the acceleration to the moving heater system.
Additionally or alternatively, embodiments may include a recoil alignment mechanism having a rail-mounted frame which receives the blank and accurately maintains the alignment of the blank throughout the forming process. Broadly, in one implementation a blank support frame may be mounted on a rail extending between the dies of the press, with one or more springs, nested elements, or other collapsible members extending between a moving portion of the press and the frame so as to transfer the movement of the moving portion of the press to the frame rather than directly to the blank during the forming process.
In more detail, the blank of (e.g., thermoplastic composite) material may be received and held by the frame and positioned within the press and properly aligned with the dies. The blank may be pre-heated in a fixed oven as in the prior art or heated in situ using the moveable heater elements described above. Regardless of how the blank is heated, once the blank has been heated and the heated blank is positioned and aligned within the press, the press may be activated such that the moving die pushes the frame toward the fixed die and the collapsible members collapse as the dies are brought together around the blank to form the blank into the part before the blank cools below a minimum temperature.
This advantageously allows for the frame with the pre-aligned blank to travel with the press as it closes, the collapsible members compress or otherwise collapse as the press closes, and the frame lands on the static die half and holds the aligned blank parallel to the dies until closure. In particular, embodiments address problems and limitations in the prior art by moving the frame with the press as it closes and by being mounted on collapsible members which collapse with the closure of the press to hold the blank to in the correct alignment until the press fully closes and the blank is formed under pressure. As the dies are moved together, the collapsible members contact the frame and compress as the blank is formed, and as the elements of the dies are moved apart, the collapsible members extend. Because the collapsible members maintain contact with the frame within which the blank is held, the blank is less likely to move out of alignment as the dies are moved together to form the blank. Further, misalignments and other problems due to temperature differences between the heated blank and the dies are reduced or eliminated by pushing against the frame rather than the blank and bringing the moving die into contact with the blank only once the frame is resting against the static die at the last moment when forming actually occurs.
Referring to
The press 26 may be configured to stamp- or mold-form the blank 22 once the blank 22 had been sufficiently heated and accurately aligned. The press 26 may employ substantially any suitable press technology for accomplishing this function. In one implementation, the press 22 may include a moveable press portion 27 including the first die 28, a corresponding static or fixed press portion 29 including the second die 30, and an actuation mechanism 42 configured to open and close the press 26. In more detail, the actuation mechanism 42 may be configured to move the moveable press portion 27 away from the fixed press portion 29 to receive the heated blank 22, as seen in
The frame 32 may be configured to receive and hold the blank 22 in an aligned position between the first and second dies 28,30. In one implementation, the frame 32 may be mounted on a first positioning mechanism 44 configured to move the frame 32 to a first position which is not within the press 26 in order to receive the blank 22, as seen in
The heater elements 34 may be configured to advance to a first position within the open press 26 to heat the blank 22 in the aligned position to a melt or forming temperature, as seen in
In a first embodiment, shown in
In a second embodiment, shown in
The alignment mechanism 36 may be configured to maintain the blank 22 in the aligned positioned between the first and second dies 28, 30 as the press 26 is closed to form the blank 22 into the part 24. The rail component 38 of the alignment mechanism 36 may extend between the first and second portions of the press 26 and through the frame 32, and may be configured to allow the moveable portion of the press having the first die 28 and the frame 32 to slide between a first position in which the first and second dies 28, 30 and the frame 32 are spaced apart, as seen in
Implementations of the system 20 may further include an indexing or other alignment mechanism for aligning the first die 28, second die 30, frame 32, and/or blank 22 within the closing press. Example indexing or other alignment mechanisms include or may employ magnets, holes and corresponding pins, light emitting diodes and photodetectors, grommets in holes, strip clamps with holes in extensions, wire cables and beads, consolidated metal tabs coordinated to ply drops, and/or sacrificial material/shear edge holders.
Referring also to
The heater element 34 may be advanced to a first position within the open press 26 (e.g., between the first and second dies 28,30) to heat the blank 22 held by the frame 32 in the aligned position to a forming temperature, as shown in 124 and seen in
The heated blank 22 may be maintained in the aligned positioned between the first and second dies 28, 30 as the first and second dies 28, 30 are brought together to form the blank 22 into the part 24, as shown in 128. In more detail, this may include the following substeps. The frame 32 may be spaced apart from the first die 28 by the collapsible member 40 extending between the first die 28 and the frame 32, wherein the first die 28 and the frame 32 are slidingly mounted on a rail 38 extending between the first and second dies 28, 30 and through the frame 32, as shown in 130 and seen in
The first and second dies 28, 30 may then be moved apart so that the formed part 24 can be unloaded and the process can be repeated, as desired or needed, as shown in 136 and seen in
Having thus described one or more embodiments of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following:
