Patent Application
20170036297
This disclosure relates generally to the fabrication of parts into desired shapes, and more particularly to forming tooling and fabricating parts made from metal powder into desired shapes using such tooling.
The fabrication of parts using powder metallurgy offers advantages over traditional metallurgy. For example, parts made from powder metallurgy often are fabricated at lower costs, closer to net shape, and with improved metal alloys compared to traditional metallurgy.
Conventional powder metallurgy techniques include encapsulating and consolidating metal powders within an enclosure. The enclosure is formed by welding together two or more metal sheets. Conventional techniques for welding sheets together to form an enclosure include placing welds in the portion of the sheets defining the space used to shape the part. Such welds tend to impart residual stress on the sheets, which can cause the sheets to twist and deform during fabrication of the part.
Further, according to traditional techniques, the enclosures are limited to forming parts with only rudimentary or simple shapes. To fabricate parts into final shapes that are more complex, a significant amount of material must be machined away from the parts, which increases the time and complexity associated with fabrication of the parts. Traditionally, a ratio of a total volume of the rudimentary shape to a total volume of the final machined shape is at least between about 30 and about 60. Because metal powders are relatively expensive, the loss of material associated with machining parts with rudimentary shapes into more complex shapes results in added manufacturing costs.
The subject matter of the present application provides embodiments of methods for forming tooling, and associated methods and apparatuses for fabricating a part made from metal powder, that overcome the above-discussed shortcomings of prior art techniques. In other words, the subject matter of the present application has been developed in response to the present state of the art, and in particular, in response to shortcomings of conventional methods and apparatuses for forming tooling used to fabricate parts made from metal powder.
According to one embodiment, a first method of forming tooling for fabricating a part made from a metal powder includes forming a first sheet. The first sheet includes a first protrusion that defines a first cavity and a first flange that extends about an entire periphery of the first protrusion. The first method also includes forming a second sheet that includes a second flange. Additionally, the first method includes arranging the first sheet and the second sheet adjacently to each other to abut together the first flange of the first sheet and the second flange of the second sheet and to define an enclosure. The enclosure includes a void defined between the first cavity of the first sheet and the second sheet. The void has a shape of the part. The first method further includes welding together the first flange of the first sheet and the second flange of the second sheet along a portion of the first flange spaced away from the first protrusion.
In some implementations of the first method, the second sheet includes a second protrusion that defines a second cavity. The second flange extends about an entire periphery of the second protrusion. The void is defined between the first cavity of the first sheet and the second cavity of the second sheet. Welding together the first flange of the first sheet and the second flange of the second sheet includes welding along a portion of the second flange spaced away from the second protrusion.
According to certain implementations of the first method, welding together the first flange of the first sheet and the second flange of the second sheet includes forming a continuous weld about the entire peripheries of the first protrusion of the first sheet and the second protrusion of the second sheet. The continuous weld can be spaced the same distance away from the first protrusion of the first sheet and the second protrusion of the second sheet about the entire peripheries of the first protrusion and the second protrusion. The continuous weld can be spaced a distance away from the first protrusion and the second protrusion. The distance is at least 0.125 inches in some implementations.
In certain implementations of the first method, the first cavity has a first three-dimensional shape and the second cavity has a second three-dimensional shape. The first three-dimensional shape of the first cavity can be the same as the second three-dimensional shape of the second cavity. A shape of the first protrusion may complement the first three-dimensional shape of the first cavity, and a shape of the second protrusion may complement the second three-dimensional shape of the second cavity. At least one of the first three-dimensional shape of the first cavity and the second three-dimensional shape of the second cavity can have a complex geometry.
According to some implementations of the first method, a periphery of the first protrusion is the same shape and size as a periphery of the second protrusion. Arranging the first sheet and the second sheet adjacently to each other includes aligning the peripheries of the first protrusion and the second protrusion.
In one implementation of the first method, the first flange and the second flange are planar.
According to certain implementations, the first method further includes forming a through-channel in at least one of the first flange and the second flange. The through-channel is open to the void at a first end of the through-channel and open to an exterior of the enclosure at a second end of the through-channel opposite the first end of the through-channel.
In certain implementations of the first method, the first flange of the first sheet and the second flange of the second sheet are welded together via friction stir welding. In further implementations of the first method, at least one of the first sheet and the second sheet are formed via incremental sheet forming.
According to one embodiment, a second method of fabricating a part made from a metal powder includes forming a first sheet. The first sheet includes a first protrusion that defines a first cavity and a first flange that extends about an entire periphery of the first protrusion. The second method also includes forming a second sheet. The second sheet includes a second protrusion that defines a second cavity and a second flange that extends about an entire periphery of the second protrusion. The second method further includes arranging the first sheet and the second sheet adjacently to each other to abut together the first flange of the first sheet and the second flange of the second sheet and to define an enclosure. The enclosure includes a void defined between the first cavity of the first sheet and the second cavity of the second sheet. The void has a shape of the part. Additionally, the second method includes welding together the first flange of the first sheet and the second flange of the second sheet along a portion of the first flange spaced away from the first protrusion and a portion of the second flange spaced away from the second protrusion. The second method also includes filling the void of the enclosure with metal powder. Further, the second method includes heating the enclosure and metal powder in the void of the enclosure to a threshold temperature and pressurizing the enclosure and metal powder in the void of the enclosure to a threshold pressure to form a part in the void of the enclosure. The second method also includes removing the part from the enclosure.
In some implementations of the second method, the part in the void of the enclosure has an intermediate shape. The second method can further include shaping the part from the intermediate shape to a final shape. A ratio of a total volume of the intermediate shape and a total volume of the final shape can be less than about 6. The final shape of the part is a complex three-dimensional shape in certain implementations.
According to some implementations of the second method, the first cavity has a first three-dimensional shape and the second cavity has a second three-dimensional shape. The void can have a third-three-dimensional shape that includes a combination of the first three-dimensional shape and the second three-dimensional shape. The part in the void of the enclosure has the third three-dimensional shape.
In certain implementations, the second method also includes forming a through-channel in at least one of the first flange and the second flange. The through-channel is open to the void at a first end of the through-channel and open to an exterior of the enclosure at a second end of the through-channel opposite the first end of the through-channel. The second method further includes passing the metal powder through the through-channel to fill the void of the enclosure.
According to yet another embodiment, an apparatus for fabricating a part made from a metal powder includes a first sheet with a first protrusion that defines a first cavity and a first flange that extends about an entire periphery of the first protrusion. The apparatus also includes a second sheet with a second protrusion that defines a second cavity and a second flange that extends about an entire periphery of the second protrusion. The second flange of the second sheet abuts the first flange of the first sheet to define a void between the first cavity of the first sheet and the second cavity of the second sheet. The void has a shape of the part. The apparatus also includes a continuous weld formed in the first flange and the second flange. The continuous weld is spaced apart from the first protrusion of the first sheet and the second protrusion of the second sheet.
The described features, structures, advantages, and/or characteristics of the subject matter of the present disclosure may be combined in any suitable manner in one or more embodiments and/or implementations. In the following description, numerous specific details are provided to impart a thorough understanding of embodiments of the subject matter of the present disclosure. One skilled in the relevant art will recognize that the subject matter of the present disclosure may be practiced without one or more of the specific features, details, components, materials, and/or methods of a particular embodiment or implementation. In other instances, additional features and advantages may be recognized in certain embodiments and/or implementations that may not be present in all embodiments or implementations. Further, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the subject matter of the present disclosure. The features and advantages of the subject matter of the present disclosure will become more fully apparent from the following description and appended claims, or may be learned by the practice of the subject matter as set forth hereinafter.
In order that the advantages of the subject matter may be more readily understood, a more particular description of the subject matter briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the subject matter, they are not therefore to be considered to be limiting of its scope. The subject matter will be described and explained with additional specificity and detail through the use of the drawings, in which:
Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. Similarly, the use of the term “implementation” means an implementation having a particular feature, structure, or characteristic described in connection with one or more embodiments of the present disclosure, however, absent an express correlation to indicate otherwise, an implementation may be associated with one or more embodiments.
Referring to
As shown in
The size and shape of the first and second cavities 150, 152 can be the same or different depending on a desired shape of the part being fabricated. In the illustrated embodiment, the size and shape of the first and second cavities 150, 152 are the same such that the shape of the part 190 is symmetrical across its midline. Alternatively, the size and shape of the first and second cavities 150, 152 can be differently sized, differently shaped, or both differently sized and shaped to produce a part that is asymmetrical.
The first and second protrusions 114, 116 extend perpendicularly or obliquely away from the first and second flanges 118, 120, respectively. Referring to
Although both the first and second protrusions 114, 116 are shown to define first and second cavities 150, 152 both with three-dimensional shapes, in some embodiments, one of the first and second cavities 150, 152 may have a three-dimensional shape, while the other of the first and second cavities does not. For example, in one embodiment, the first sheet 110 has a protrusion that defines a three-dimensional cavity, and the second sheet 112 does not have a protrusion. Although the second sheet 112 may be a flat sheet, because the cavity of the protrusion of the first sheet 110 is three-dimensional, the resulting part also will be three-dimensional.
In some embodiments, such as in the illustrated embodiment, the first and second flanges 118, 120 are planar. In other words, the interface surfaces 174, 176 of the first and second flanges 118, 120 are planar (e.g., flat). For example, as in the illustrated embodiment, the interface surface 174 of the first flange 118 can be co-planar about the entire periphery 125 of the first protrusion 114, and the interface surface 176 of the second flange 120 can be co-planar about the entire periphery 127 of the second protrusion 116, such that when coupled together the entirety of the first and second flanges are parallel to each other. However, in other embodiments, although planar, some portions of the first flange 118 are not co-planar with other portions of the first flange, and some portions of the second flange 120 are not co-planar with other portions of the second flange. For example, one side of the interface surfaces 174, 176 of the first and second flanges 118, 120 may be angled in a first direction and another side of the first and second flanges may be non-angled or angled in a different direction.
According to other embodiments, the first and second flanges 118, 120 are non-planar. In other words, the interface surfaces 174, 176 of the first and second flanges 118, 120 can be sharply or gradually contoured. For example, in certain implementations, the interface surfaces 174, 176 may be rounded, pointed, or the like. In some implementations, one of the interfaces surfaces 174, 176 is concave and the other of the interface surfaces is convex, such that the convex surface is nestably engaged with the concave surface.
Referring to
The first protrusion 114 and the first flange 118 of the first sheet 110 form a one-piece monolithic construction, and the second protrusion 116 and the second flange 120 of the second sheet 112 form a one-piece monolithic construction, in some embodiments. In the illustrated embodiment, each of the first and second sheets 110, 112 has a constant thickness across at least one of the respective protrusions and flanges of the first and second sheets. For example, in one implementation, the first protrusion 114 of the first sheet 110 has a constant thickness, and the second protrusion 116 of the second sheet 112 has a constant thickness. In such an implementation, an exterior surface 160 of the first protrusion 114 complements (e.g., has the same shape and size as) the interior surface 164 of the first protrusion. Likewise, in such an implementation, an exterior surface 162 of the second protrusion 116 complements the interior surface 166 of the second protrusion. In the same or an alternative example, the flange 118 of the first sheet 110 has a constant thickness and the flange 120 of the second sheet 112 has a constant thickness. In yet some embodiments, the thickness across at least one of the respective protrusions and flanges of the first and second sheets 110, 112 may vary. Whether constant or varying, the thickness of the first and second sheets 110, 112 (e.g., distance between interior and exterior surfaces) is much smaller than the width and length of the sheets such that the first and second sheets have a generally sheet-like configuration.
Referring to
After the first and second sheets are formed at 210, 220, respectively, the method 200 includes abutting together the flanges of the first and second sheets to define a void between cavities defined by the protrusions of the first and second sheets at 230. In other words, the method 200 includes arranging the first and second sheets adjacently to each other such that the flanges of the sheets abut each other. More specifically, in the illustrated embodiment as shown in
After the first and second sheets are arranged adjacently to each other and the first and second flanges abut each other, the method 200 includes welding together the first and second flanges at 240 to fixedly couple together the first and second sheets to form an enclosure. The weld or weldment formed in the first and second flanges at 240 of the method 200 is spaced away from the first and second protrusions of the first and second sheets, respectively. In certain implementations, the weld is spaced away from the first and second protrusions by being non-adjoining or non-coincident with the protrusions. In other words, some portion of the flange is positioned between the weld and the protrusions. Spacing the weld away from the protrusions prevents residual stresses from being formed in and deformation of the protrusions by the weld.
Referring to
The weld 130 can be formed using any of various fusion welding techniques configured to thermomechanically alter the materials of adjoining sheets to permanently mix together the materials and join together the sheets. For example, the weld 130 can be formed using friction stir welding (FSW), laser welding, arc welding, and the like. FSW techniques include the use of a wear-resistant rotating tool to join adjoining sheets together. The rotating tool includes a shoulder from which extends a profiled pin. In the illustrated embodiment, the shoulder frictionally engages or presses against the outer surface 170, 172 of one of the flanges 118, 120 of the first and second sheets 110, 112. With the shoulder against the outer surface of a flange, the profiled pin penetrates at least partially through both the first and second flanges 118, 120. Friction due to rotation of the tool generates heat in the material of the first and second flanges 118, 120. The heat generated by the rotating tool is sufficient to soften the material and thermomechanically alter the material without melting the material. The softened material of the first and second flanges 118, 120 is stirred together and allowed to cool (e.g., harden) to permanently join together the material and thus the first and second flanges.
A continuous weld, as opposed to a spot weld, is formed in a desired pattern using FSW techniques by translationally moving the rotating tool, while engaging and thermomechanically altering the flanges, along the outer surface of one of the flanges in the desired pattern. As mentioned above, the desired pattern complements the shape of the outer peripheries 125, 127 of the first and second protrusions 114, 116. Generally, the diametric extent or periphery of the shoulder of the tool defines the inner and outer peripheries 132, 134 of the weld 130. In other words, thermomechanical alternation of the material of the first and second flanges 118, 120 is contained within the footprint of the shoulder of the rotating tool. In this manner, controlling the position of the shoulder of the rotating tool relative to the outer peripheries 125, 127 of the first and second protrusions 114, 116 also controls the location of the weld 130 relative to the outer peripheries of the first and second protrusions. Therefore, the rotating tool is positioned such that the shoulder of the rotating tool is the predetermined distance D away from the outer peripheries 125, 127 of the protrusions, which results in the weld 130 being the desired distance D away from the outer peripheries.
After the flanges of the first and second sheets are welded together at 240 to form an enclosure defining a void, the method 200 includes filling the void with metal powder at 250. In the illustrated embodiment, the void 154 of the enclosure 100 is filled with metal powder 180 by passing the metal powder through a through-channel 140 formed in the enclosure 100. Accordingly, filling the void with metal powder at 250 may include forming a through-channel in at least one of the flanges of the first and second sheets of the enclosure. The through-channel 140 can be formed in at least one of the first and second flanges 118, 120 of the first and second sheets 110, 112, respectively. As shown, the through-channel 140 is defined by two opposing sub-channels 140A, 140B formed in the interface surfaces 174, 176 of the first and second flanges 118, 120, respectively. In other words, half of the through-channel 140 is formed in the first flange 118 and the other half of the through-channel is formed in the second flange. In alternative embodiments, the entirety of the through-channel 140 can be formed in one or the other of the first and second flanges 118, 120. Notwithstanding how the through-channel 140 is formed, the through-channel is configured to be open to the void on one end and open to an exterior of the enclosure 100 on another other end. Accordingly, the through-channel 140 extends through the flanges 118, 120 and into the void 154 In this manner, after the enclosure 100 is formed, access to the void 154, such as for passing metal powder 180 into the void, is available from outside the enclosure.
The metal powder 180 can be any of various metal powders known in the art. For example, in some implementations, the metal powder is one or more of an aluminum powder, an iron powder, and the like. The metal powder 180 may include additives, such as lubricant wax, carbon, copper, and nickel, that help to bind the metal powder together during a part forming process. Although a metal powder is the focus of the present disclosure, non-metal powders may be used.
After the void of the enclosure is filled with metal powder at 250, the method 200 may include evacuating air from the void in preparation for a part forming process. The air may be removed using a vacuum pump or other similar device. In one implementation, a vacuum pump evacuates air from within the void using the same through-channel used to supply metal powder into the void. However, according to other implementations, a secondary through-channel is used to evacuate air from the void.
When the enclosure is filled with metal powder and air is evacuated from the void, the through-channel(s) are sealed. The through-channel(s) can be sealed using any of various methods, such as welding shut the through-channel(s), collapsing the through-channel(s), and the like. In the illustrated implementation, the through-channel 140 is welded shut using the same welding technique used to join together the first and second flanges 118, 120. In other implementations, the through-channel can be welded shut using a different welding technique. Because in some implementations the through-channel 140 may not be welded shut using the same continuous weld 130 formed around the peripheries 125, 127 of the protrusions 114, 116, or may be collapsed shut, as defined herein a weld is a continuous weld in the flanges about an entire periphery of the protrusions if the weld in the flanges extends about the entire periphery of the protrusions but for the portion of the flanges occupied by the through-channel.
After the void of the enclosure is filled with metal powder, air is evacuated from the void, and the through-channel(s), or other means used to fill the void and evacuate the air, is sealed, the method 200 includes heating and pressurizing the metal powder to form a part at 260. Referring to
After the metal powder is heated and pressurized such that the formed part is compacted to a desired density, the method 200 includes removing the part from the void of the enclosure at 270. In some implementations, the part can be removed from the void of the enclosure by cutting through the enclosure. For example, a cutting tool may be employed to cut through one or both of the first and second sheets 110, 112 to form an opening through which the part 190 can be removed. Removing the part 190 can also include bending or peeling back the cut sheets to access the part 190.
The shape of the part in the enclosure, and the shape of the part upon being removed from the enclosure, can be considered to have an intermediate three-dimensional shape. In certain embodiments, the part is further shaped from the intermediate three-dimensional shape into a final three-dimensional shape. Further shaping of the part from the three-dimensional shape to the final three-dimensional shape can include removing material from the part. The final three-dimensional shape of the part can be defined as the shape of the part during use for its intended purpose. Because the enclosure 100 and method 200 of forming tooling and fabricating a part using the tooling facilitate the formation of complex three-dimensional parts, only a minimal amount of material is removed from the part with the intermediate three-dimensional shape to achieve the final three-dimensional shape. In some implementations, a ratio of a total volume of the intermediate shape to a total volume of the final shape is less than or equal to between about 3.0 and about 6.0.
In the above description, certain terms may be used such as “up,” “down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” “over,” “under” and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships. But, these terms are not intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface simply by turning the object over. Nevertheless, it is still the same object. Further, the terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise. Further, the term “plurality” can be defined as “at least two.”
Additionally, instances in this specification where one element is “coupled” to another element can include direct and indirect coupling. Direct coupling can be defined as one element coupled to and in some contact with another element. Indirect coupling can be defined as coupling between two elements not in direct contact with each other, but having one or more additional elements between the coupled elements. Further, as used herein, securing one element to another element can include direct securing and indirect securing. Additionally, as used herein, “adjacent” does not necessarily denote contact. For example, one element can be adjacent another element without being in contact with that element.
As used herein, the phrase “at least one of”, when used with a list of items, means different combinations of one or more of the listed items may be used and only one of the items in the list may be needed. The item may be a particular object, thing, or category. In other words, “at least one of” means any combination of items or number of items may be used from the list, but not all of the items in the list may be required. For example, “at least one of item A, item B, and item C” may mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, “at least one of item A, item B, and item C” may mean, for example, without limitation, two of item A, one of item B, and ten of item C; four of item B and seven of item C; or some other suitable combination.
Unless otherwise indicated, the terms “first,” “second,” etc. are used herein merely as labels, and are not intended to impose ordinal, positional, or hierarchical requirements on the items to which these terms refer. Moreover, reference to, e.g., a “second” item does not require or preclude the existence of, e.g., a “first” or lower-numbered item, and/or, e.g., a “third” or higher-numbered item.
The schematic flow chart diagrams included herein are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of one embodiment of the presented method. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated method. Additionally, the format and symbols employed are provided to explain the logical steps of the method and are understood not to limit the scope of the method. Although various arrow types and line types may be employed in the flow chart diagrams, they are understood not to limit the scope of the corresponding method. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the method. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted method. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown.
The present subject matter may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
