Patent Application
20190291167
The present disclosure relates to flow forming of hollow shafts and more particularly to backward flow forming of hollow shafts.
Flow forming technology is a metal forming technique whereby a hollow metal blank or preform is mounted on a rotating mandrel and the material of the preform may be made to flow (plastic deformation) axially, with respect to the mandrel, under pressure of one or more rollers. In this regard, the interior diameter of the work piece remains constant with respect to the diameter of the mandrel and the outer diameter of the work piece may be reduced.
In various embodiments, an apparatus for backward flow forming a material is provided. The apparatus may comprise a mandrel having a headstock at a proximate end of the mandrel, the mandrel configured to rotate about an axis, a plurality of rollers disposed radially outward of the mandrel configured to exert force on the material to form a work piece at a plastic deformation zone, wherein the work piece flows from the plastic deformation zone between the plurality of rollers and the mandrel toward a distal end of the mandrel, and a catcher, coaxial to the mandrel, and removably coupled to the work piece at a traveling end of the work piece.
In various embodiments, the traveling end further comprises a coupling feature. In various embodiments, the plurality of rollers are configured to travel from the distal end of the mandrel toward the headstock. In various embodiments, the catcher is configured to travel with the traveling end of the work piece. In various embodiments, the catcher exerts a tension in the work piece. In various embodiments, the catcher is configured to deflect the traveling end of the work piece with respect to the axis of the mandrel by oscillating with respect to the axis of the mandrel. In various embodiments, the deflection of the traveling end with respect to the axis of the mandrel is 5° to 15°. In various embodiments, shear banding is formed within the material at the plastic deformation zone in response to the deflection of the traveling end. In various embodiments, the catcher comprises one of a grab or a clamp. In various embodiments, the mandrel comprises a complex geometry having curves, multi-radial curves, or steps. In various embodiments, shear banding is formed within the material at the plastic deformation zone in response to the deflection of the roller. In various embodiments, the deflection of the roller with respect to the axis of the mandrel is 5° to 15°.
In various embodiments, a method for improving backward flow forming of a material is provided. The method may comprise mounting the material in an apparatus for backward flow forming and applying a load to a plurality of rollers forming a plastic deformation zone in the material between the plurality of rollers and a mandrel, advancing the plurality of rollers toward a headstock at a proximate end of the mandrel, wherein a work piece flows from the plastic deformation zone between the plurality of rollers and the mandrel toward a distal end of the mandrel, and coupling the work piece to a catcher at a traveling end of the work piece.
In various embodiments, the method may also comprise machining a coupling feature in the work piece proximate the traveling end of the work piece. In various embodiments, the method may also comprise applying a tension, defined between the catcher and the plastic deformation zone, at the traveling end of the work piece. In various embodiments, the coupling comprises clamping the work piece to the catcher. In various embodiments, the method may also comprise deflecting the traveling end of the work piece with respect to an axis of the mandrel. In various embodiments, the deflection with respect to the axis of the mandrel is 5° to 15°. In various embodiments, the method may also comprise forming shear banding within the material at the plastic deformation zone in response to the deflection.
In various embodiments a control system for backward flow forming of shafts is provided. The system may comprise a first sensor in electronic communication with a controller, the first sensor configured to measure at least one of a tension parameter, a deflection parameter, a catcher parameter, or an apparatus parameter, a catcher drive system in electronic communication with the controller, and a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising receiving, by the controller, an external command and the first catcher parameter, and controlling, by the controller, the catcher drive system in response to the first catcher parameter and the external command.
In various embodiments, the operations further comprise receiving, by the controller, the tension parameter and controlling, by the controller, the catcher drive system to maintain the tension parameter at a constant.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the figures, wherein like numerals denote like elements.
All ranges and ratio limits disclosed herein may be combined. It is to be understood that unless specifically stated otherwise, references to “a,” “an,” and/or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural.
The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the exemplary embodiments of the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not limitation.
The scope of the disclosure is defined by the appended claims and their legal equivalents rather than by merely the examples described. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, coupled, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
Flow forming is a metal forming process whereby a hollow metal blank is mounted on a rotating mandrel and the metal is displaced axially along the mandrel by one or more rollers which traverse the length of the mandrel. In various embodiments, the metal blank may be a preform shape such as, for example, one of a sleeve or a cup. Flow forming may be performed either as backward flow forming or forward flow forming in accordance with the direction of axial flow during the flow forming process. In the forward flow forming technique, a blank is held between the mandrel and a tailstock while the rollers traverse from the tailstock along the mandrel tending thereby to displace material in the same direction as the traveling rollers. In various embodiments, forward flow forming tends to include a blank having a base or an internal flange or other such feature suitable for mounting in the tailstock. In the backward flow forming technique, a blank is held is held against a headstock and, as the rollers advance forward toward the headstock, the work piece is extruded backward between the roller and the mandrel.
Backward flow forming tends to be suited for blank materials having low ductility, tending thereby to allow rollers to apply high force to plasticize the blank material under the contact point. In various embodiments, the flow of material under the rollers comprises two components an axial flow component along the axis of the mandrel and a circumferential flow component. In various embodiments, backward flow forming may be prone to non-uniform dimensioning across the length of the work piece which may result from the high forces used to plasticize materials having low ductility. In various embodiments, a backward flow forming work piece may tend to sag or deform under its own weight and/or lose concentricity as the work piece travels away from the mandrel. In various embodiments, a lack of plasticity may tend to cause distortions like bell mouthing at a free end of the work piece or a preform. In various embodiments, a lack of plasticity may require a multiple-pass flow forming with or without annealing step in between. In various embodiments, a lack of plasticity in the blank material and the work piece (i.e. low ductility) may tend to increase friction against the mandrel and may tend to induce bulging and cracking of the work piece and/or the blank material.
In various embodiments and with reference to
With additional reference to
In various embodiments, catcher 124 may be configured to oscillate rotationally with respect to the rotational axis and tending thereby to cause traveling end 122 of work piece 114 to deflect relative to axis A-A. In various embodiments, work piece 114 tends to have a higher strength than the material at plastic deformation zones 112 and tends to transfer the oscillations into the plastic deformation zones 112. In this regard, the oscillation of catcher 124 may tend to trigger a plastic deformation in a localized zone of shear bands tending thereby to reduce material stresses in the plastic deformation zones and, in response, tending to improve material formability, tending to increase material microstructure homogeneity through the material thickness, and tending to reduce material susceptibility to cracking. In this regard, compressive force F at rollers 108 may tend to be reduced in proportion to the improvement in material formability tending thereby to increase an operational life of rollers 108. In various embodiments, the oscillations may be about 10° off axis A-A (i.e. a deflection as an absolute value) where the term “about” in this context means±5°. Stated another way, as work piece 114 continues to flow along and away from mandrel 104 the oscillations may tend to cause traveling end 122 of work piece 114 to trace a sinusoidal path with axis A-A defining a relative zero position of the wave form traced by traveling end 122. In various embodiments, mandrel 104 may be heated. In various embodiments, preform 102 may be pre-heated prior to backward flow forming.
In various embodiments and with reference to
With reference to
Benefits and other advantages have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, and any elements that may cause any benefit or advantage to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C.
Systems, methods and apparatus are provided herein. In the detailed description herein, references to “various embodiments,” “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is invoke 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
