The described invention relates in general to manufacturing systems and methods and more specifically to a system and method for applying ultrasonic excitation to segmented dies used in manufacturing processes such as those used in the automotive industry.
The potential of using ultrasonic vibrations to reduce friction during sheet metal forming processes, e.g. in deep drawing, has been recognized and investigated over the years, with favorable results having been reported, both in forming processes, and in the fundamental mechanics of friction reduction. One sheet metal forming area where ultrasonic friction reduction would presumably have a major benefit is in the forming/stamping of auto body parts. In this field, new challenges are continually emerging as efforts are made to form higher strength steel and aluminum alloys having complex shapes. However, in forming and stamping of auto body parts and the like, large steel dies, blank holders and punches are used, not uncommonly having weights in excess of several thousand kilograms and lateral dimensions on orders of meters and of significant thicknesses. Unfortunately, achieving ultrasonic excitation of such large masses is beyond the current capabilities of high power ultrasonic systems and would seemingly rule out this field of application. Furthermore, current industry methods for friction alleviation typically involve the application of coatings to a die surface, which has the disadvantages of (i) requiring renewal as it wears away with repeated stampings; (ii) leaving residues on the stamped sheet metal surfaces which must be later removed; and (iii) the subsequent disposal of those residues.
However, three primary factors suggest that there are significant applications for high power ultrasonics (HPU) in the forming of auto body parts and the like. First, in the stamping of auto parts, it has been observed that only certain critical areas of a die are unusually challenging to the forming operation. Thus, while a die may indeed be of large size and mass, only a comparatively small region might have a form or shape factor that may compromise die performance. Accordingly, the amount of die volume/mass associated with a problem region could be within a range that could be feasibly vibrated by ultrasonic vibrations, provided that region could be acoustically isolated from the remaining die mass. Secondly, it is current practice to segment portions of a die for various purposes, but most notably to permit repair or replacement of high wear regions. Although it would seem that the boundaries of the segmented regions would be susceptible to causing marking of the stamped parts, the stamping process is actually fairly tolerant of die surface details insofar as part markings. Thirdly, through prior work on ultrasonic friction reduction, processes have been developed for acoustically isolating and securing ultrasonically excited blocks that are believed able to find application to the present issue of both ultrasonically vibrating a die segment and securing it within an overall die structure. Thus, there is an ongoing need for a system for applying ultrasonic excitation to segmented dies.
The following provides a summary of certain exemplary embodiments of the present invention. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the present invention or to delineate its scope.
In accordance with one aspect of the present invention, a first forming die is provided. This forming die includes a body, wherein the body of the forming die includes at least one opening created therein; at least one die segment, wherein the at least one die segment is adapted to be inserted into the at least one opening in the body of the forming die, and wherein the at least one die segment is further adapted to receive ultrasonic vibrations; and at least one geometric feature formed within the at least one die segment, wherein the at least one geometric feature affects the ultrasonic vibrations in a predetermined manner.
In accordance with another aspect of the present invention, a second forming die is provided. This forming die includes a body, wherein the body of the forming die includes at least one opening created therein; at least one die segment, wherein the at least one die segment is adapted to be inserted into the at least one opening in the body of the forming die, and wherein the at least one die segment is further adapted to receive ultrasonic vibrations; at least one source of ultrasonic vibrations in communication with the at least one die segment for directing ultrasonic vibrations into the die segment, wherein the at least one source of ultrasonic vibrations is either embedded within the at least one die segment or external to the at least one die segment; and at least one geometric feature formed within the at least one die segment, wherein the at least one geometric feature affects the ultrasonic vibrations in a predetermined manner.
In yet another aspect of this invention, a third forming die is provided. This forming die includes a body, wherein the body of the forming die includes at least one opening created therein; at least one die segment, wherein the at least one die segment is adapted to be inserted into the at least one opening in the body of the forming die, and wherein the at least one die segment is further adapted to receive ultrasonic vibrations; and at least one geometric feature formed within the at least one die segment, wherein the at least one geometric feature affects the ultrasonic vibrations in a predetermined manner, and wherein the at least one geometric feature includes a cylindrical bore that is oriented transversely, side-to-side, within the at least one die segment; a cylindrical bore that is oriented vertically within the at least one die segment; a square cutout that is oriented vertically within the at least one die segment; a rectangular cutout that is oriented transversely, side-to-side, within the at least one die segment at a predetermined angle; or combinations thereof.
Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the exemplary embodiments. As will be appreciated by the skilled artisan, further embodiments of the invention are possible without departing from the scope and spirit of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature.
The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description given below, serve to explain the principles of the invention, and wherein:
Exemplary embodiments of the present invention are now described with reference to the Figures. Although the following detailed description contains many specifics for purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.
The purpose of the present invention is to apply ultrasonic vibrations to one or more regions of a large stamping die in order to reduce friction between the sheet metal being formed and the surface of the die, thereby improving the formability of the metal at critical shape locations, as well as reducing galling, tearing and cracking of the sheet metal. This desired effect is accomplished by acoustically isolating a segment (or segments) of the die and embedding within the die, an ultrasonic vibration source (i.e., an ultrasonic transducer) that creates resonant vibrations of the die, of varying magnitudes, at its several surfaces thereby creating an ultrasonic friction reduction effect having various benefits. Thus, the present invention typically includes the steps of: (i) identifying a critical region (or regions) of a die where friction reduction would have greatest effect (or effects); (ii) acoustically isolating a segment (or segments) of the die, from the critical region (or regions) into a manageable mass (or masses) that is capable of being ultrasonically excited; and (iii) incorporating within that mass a source of ultrasonic excitation, i.e., an ultrasonic transducer system. The ultrasonic excitation of the die segment by an internal source versus transmitting vibrations from an external source to the die segment along with the specific means of its acoustic isolation, are among the novel features of the invention.
With reference now to the Figures, a first exemplary embodiment of an acoustically isolated ultrasonic die is shown in
With regard to holding ultrasonic die segment 12 within a portion of large stamping die 14, it is important to acoustically isolate the ultrasonic die segment from the surrounding die structure, while at the same time securing it in a fixed location so that it seamlessly merges into the overall die. Two approaches, which may be used alone or in combination with one another include: (i) low friction pads 16, wherein the pads include a Frelon coating or are made from a metallic bearing material such as bronze or cast iron; and (ii) a setscrew engagement. The surrounding die structure should be capable of some disassembly in order to insert ultrasonic die segment 12 as well as to provide access for the electrical (and possibly air) connections to the die segment insert. Low friction pads 26 may be screw-in inserts, and while these inserts may be sufficient to secure die segment 12, a set screw method may also be modified for this purpose.
One important aspect of the present invention generally, is the minimal modification a large die for accommodating a die segment that will be excited with ultrasonic energy. While adjustment or modification of a large die for accommodating the general block dimensions of die segment 12 is possible (because current die practice allows for die segments) it may not always be practical to modify a large die to accommodate the various features of a particular die segment. Accordingly, in some embodiments, die segment adapting fixture 18 is included for more effectively placing die segment 12 into at least one portion of large stamping die 14.
The present invention has been described herein in reference to forming dies. A typical stamping/forming operation consists of the forming die, a blank holder and a punch, each of which may have large mass and dimensions (as noted earlier for a die). This invention, i.e., an ultrasonically activated, embedded die insert, may be applied to blank holders or punches, as well. By means of this invention it is possible to create ultrasonic vibrations in a critical segment or segments of a large die that would otherwise be impossible to ultrasonically excite to any significant vibration level, and in so doing, to reduce friction forces between sheet metal being formed and the forming die at one or more critical forming locations on the die.
With regard to the size and dimensions of die segment 12,
Accordingly, one aspect of the present invention includes creating controlled vibrations on a die surface by embedding, within the body of the die and/or in non-contacting die surfaces, various geometric features that modify surface vibrations and facilitate the friction reduction performance of the die. As will be appreciated by one of ordinary skill in the art, it is known to incorporate slot features in ultrasonic plastic welding horns for achieving uniform vibration across a welding surface, which is essential for creating a uniform weld. While slotting of this nature demonstrates that geometric features can be used to affect surface vibrations occurring on certain ultrasonic tooling, such slots are not necessarily compatible with ultrasonic metal forming dies because a smooth forming surface against the formed metal is required. To overcome this limitation, certain embodiments of this invention include various geometric features that are embedded within the body of die segment 12 and/or at the die surfaces that are not in contact with formed metal. These geometric features are effective for creating a desired or predicable ultrasonic vibration pattern at the forming surfaces of the die.
In the embodiment shown in
As described above, an important feature of the present invention is that certain predetermined segments of a large die used in ultrasonic sheet metal forming, used for the automotive, aerospace, and consumer products industries, for example, can be acoustically isolated from the balance of a massive die structure, thereby permitting ultrasonic vibrations to be concentrated in small, critical forming regions of the die, such as corners and sidewalls (see
With reference to
While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to any of the specific details, representative devices and methods, and/or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.
This patent application is a continuation-in-part of U.S. patent application Ser. No. 14/802,386 filed on Jul. 17, 2015 and entitled “Segmented Dies for Use with Ultrasonics”, which claimed the benefit of U.S. Provisional Patent Application Ser. No. 62/025,826 filed on Jul. 17, 2014 and entitled “Ultrasonic Excitation of Segmented Dies” the disclosures of which are hereby incorporated by reference herein in their entirety and made part of the present U.S. utility patent application for all purposes.