Patent ID: 12240062

DETAILED DESCRIPTION

While various inventive aspects, concepts and features of the inventions may be described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects, concepts and features may be used in many alternative embodiments, either individually or in various combinations and sub-combinations thereof. Unless expressly excluded herein all such combinations and sub-combinations are intended to be within the scope of the present inventions. Still further, while various alternative embodiments as to the various aspects, concepts and features of the inventions—such as alternative materials, structures, configurations, methods, circuits, devices and components, software, hardware, control logic, alternatives as to form, fit and function, and so on—may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or later developed. Those skilled in the art may readily adopt one or more of the inventive aspects, concepts or features into additional embodiments and uses within the scope of the present inventions even if such embodiments are not expressly disclosed herein. Additionally, even though some features, concepts or aspects of the inventions may be described herein as being a preferred arrangement or method, such description is not intended to suggest that such feature is required or necessary unless expressly so stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present disclosure, however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present disclosure, however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated. Parameters identified as “approximate” or “about” a specified value are intended to include both the specified value and values within 10% of the specified value, unless expressly stated otherwise. Further, it is to be understood that the drawings accompanying the present application may, but need not, be to scale, and therefore may be understood as teaching various ratios and proportions evident in the drawings. Moreover, while various aspects, features and concepts may be expressly identified herein as being inventive or forming part of an invention, such identification is not intended to be exclusive, but rather there may be inventive aspects, concepts and features that are fully described herein without being expressly identified as such or as part of a specific invention, the inventions instead being set forth in the appended claims. Descriptions of exemplary methods or processes are not limited to inclusion of all steps as being required in all cases, nor is the order that the steps are presented to be construed as required or necessary unless expressly so stated.

The Detailed Description merely describes exemplary embodiments and is not intended to limit the scope of the claims in any way. Indeed, the invention as claimed is broader than and unlimited by the exemplary embodiments, and the terms used in the claims have their full ordinary meaning. For example, while specific exemplary embodiments in the present application describe collets for use with weld fixtures in orbital welding systems, one of more of the features described herein may additionally or alternatively be applied to other types of welding systems, or for use in other types of fixturing applications. Additionally, while the geometries and arrangements of many of the collets described herein are such that their production is facilitated by additive manufacturing, other manufacturing methods may be utilized to fabricate collets having one or more of the features described herein, such as, for example, stacked plate assembly, machining, welding, brazing, and casting (e.g., investment casting, sand casting, lost wax casting).

FIG.2illustrates an exemplary collet member150for use with a weld fixture (e.g., the exemplary fixture assembly10ofFIG.1). While the exemplary collet member150has a semi-cylindrical body151, other collet body shapes may alternatively be utilized (e.g., rectangular, hex-shaped). The collet body151includes a clamping block engaging outer portion (shown schematically at152), a workpiece engaging inner portion (shown schematically at154), and an intermediate portion (shown schematically at153) extending radially between the outer portion152and the inner portion154. The exemplary collet member150also includes an outer radial flange158for abutting the exterior side (i.e. opposite the weld side) of the clamping block to axially position the collet member150, and a radially extending fastener bore159for receiving a fastener for affixing the collet member150to the clamping block.

According to an aspect of the present application, a collet member for a weld fixture may be configured to provide for reducing heat transfer away from a fixtured workpiece during welding. Referring toFIG.2, in an exemplary embodiment, the inner portion154of the collet body151may have a reduced thermal conductivity compared to the outer portion152of the collet body, to reduce heat transfer from the workpiece. In one such embodiment, the inner portion154of the collet body151may be provided in a different material than the outer portion152, having a lower thermal conductivity. For example, the inner portion154of the collet body151may comprise titanium alloys such as Ti-6A1-4V, zirconium and its alloys, nickel-base alloys such as Hastelloy C and X, Inconel alloy 625 and 718, and Monel alloy 400 and K-500, cobalt-base alloys such as Haynes 25 and CoCr derivatives, or any suitable material having a relatively low thermal conductivity (e.g., less than 20 W/mK) and the outer portion152may comprise stainless steel, aluminum and its alloys, copper and its alloys such as brass and bronze, or any suitable material having a higher thermal conductivity (e.g., greater than 20 W/mK). Material compatibility may be a consideration when selecting material pairs. The use of different materials may, for example, provide for cost efficiencies, and/or desirable variations in density, heat capacity, and/or corrosion behavior/resistance. In another exemplary embodiment, the inner portion154of the collet body151may have a greater material porosity (e.g., void volume fraction greater than about 15%) than the outer portion152, with the greater porosity providing for a reduced thermal conductivity.

The workpiece engaging inner portion material of the collet body may additionally or alternatively be configured to provide other desirable properties, including, for example, increased elasticity, corrosion behavior/resistance, and/or density.

While variations in materials or material properties in the collet member may be accomplished by mechanically fixing outer radial and inner radial components together to form the collet body, according to another aspect of the present application, additive manufacturing may be utilized to produce a monolithic collet body having the desired properties across the radial thickness of the collet body. Examples of additive manufacturing techniques that may be utilized include, for example: laser powder bed fusion (direct metal laser sintering or “DMLS,” selective laser sintering/melting or “SLS/SLM,” or layered additive manufacturing or “LAM”), electron beam powder bed fusion (electron beam melting or “EBM”), ultrasonic additive manufacturing (“UAM”), or direct energy deposition (laser powder deposition or “LPD,” laser wire deposition or “LWD,” laser engineered net-shaping or “LENS,” electron beam wire deposition). Providing the collet body as a single, monolithic component may eliminate assembly costs, reduce component wear, reduce adverse effects from heat cycling, improve corrosion behavior (galvanic effects, crevice, stress corrosion cracking), and reduce lead time to manufacture.

According to another aspect of the present application, heat transfer away from a fixtured workpiece may be reduced by reducing the material mass of the collet member, and/or providing cavities or air gaps in the collet member that impede thermal conduction. In one such embodiment, the intermediate portion153of the collet body151may include a plurality of rigid, radially extending members155(e.g., ribs, pins, fins, blades, etc.) extending between the outer portion152and the inner portion154to define a plurality of cavities156.

FIG.3illustrates an exemplary collet member250including a collet body251having an outer semi-cylindrical wall portion252for engagement with a clamping block, an inner semi-cylindrical wall portion254for engaging a workpiece (e.g., a tube end or other cylindrical workpiece), and a plurality of ribs255extending from the outer wall portion252to the inner wall portion254to define a plurality of cavities256. While the cavities may extend across the entire axial length of the collet member250, in the illustrated embodiment, a radial wall257is provided on a first axial side of the collet body251, to define a closed end of the cavities256. When used, for example, in an orbital weld fixture, this closed condition may be desirable for containment of the weld gases during the welding operation. In the illustrated embodiment, the radial wall257is disposed on the exterior side (i.e., opposite the weld side) of the collet member250, in axial alignment with the outer flange258. Additionally or alternatively, the radial wall257may provide further rigid reinforcement for the collet member250during clamping. In other embodiments (not shown), the radial wall may be disposed on the interior side (i.e., the weld side) of the collet member, for example, to reduce the volume to be filled by the weld gas. In still other embodiments, as shown inFIGS.14and15and discussed in greater detail below, radial walls may be provided on both axial sides of the collet body, for example, to provide additional reinforcement, such that the cavities are fully enclosed between the first and second radial walls. Fabrication of an enclosed cavity collet member may be facilitated by the use of additive manufacturing techniques, such as, for example, the techniques described in greater detail above.

While the inner wall portion254of the collet body may provide a semi-cylindrical workpiece engaging surface254a,as shown inFIG.3, in other embodiments, the inner wall portion may include one or more radially inward extending protrusions sized and positioned to reduce the contact surface between the collet member and the workpiece.FIG.4illustrates an exemplary collet member350having a collet body351with an inner wall portion354having a plurality of radially inward extending protrusions354adefining a reduced workpiece engaging surface, for example, to reduce heat transfer between the workpiece and the collet member350. These protrusions may, but need not, comprise a different material or material property than the intermediate and/or outer portions of the collet body351, for example to provide a reduced thermal conductivity (as described above), increased elasticity, improved corrosion behavior, and/or allowance for variations in dimension or shape of the workpiece engaging protrusions. As shown, the protrusions354amay extend the entire axial length of the collet member350. Alternatively, as shown inFIG.13, the protrusions may be notched or gapped to further reduce engaging surfaces. As shown inFIGS.11-13, similar protrusions may be provided on the outer wall portions, for example, to reduce surface contact between the collet member and the collet clamping block.

In the collet members250,350ofFIGS.3and4, the radially extending fastener bore259,359intersects one of the ribs255,355, for example, to facilitate positioning and alignment of the installed fastener (not shown) when affixing the collet member250,350to the clamping block. In another embodiment, a hollow fastener boss may be formed between the inner wall portion and the outer wall portion of a collet member, for example, to retain and guide the fastener when affixing the collet member to a clamping block. This fastener boss may intersect one of the radially extending members, for example, for further reinforcement.FIG.5illustrates an exemplary collet member450having a collet body451with a hollow fastener boss459adefining the fastener bore459and extending between the outer and inner wall portions452,454and intersecting one of the radially extending ribs455.

While the collet ribs described herein may form substantially solid, plate-like extensions between the inner and outer wall portions of a collet, in other embodiments, one or more of the ribs may be provided with one or more cutouts, for example, to further reduce the material mass of the collet member and/or to provide additional cavities or air gaps in the collet member that impede thermal conduction, thereby reducing the heat transfer away from a fixtured workpiece. These cutouts may produce a lattice pattern in the ribs, which may be configured to facilitate fabrication using additive manufacturing techniques, for example, by allowing both the internal and external surfaces of the collet to be self-supporting, and/or by enhancing mechanical strength or support for the component.

FIGS.11-13illustrate exemplary collet members1050,1150,1250including a collet body1051,1151,1251similar to the collet bodies251,351,451ofFIGS.3-5, with openings, apertures, or cutouts1060,1160,1260formed in the ribs1055,1155,1255to provide a lattice pattern in the ribs. In the embodiments ofFIGS.11and12, the cutouts1060,1160are diamond-shaped and arranged to provide rigid, intersecting solid walls arranged for enhanced mechanical strength, and for manufacturability using 3D printing or other additive manufacturing techniques. In the embodiment ofFIG.13, the cutouts1260are radially extending ovals arranged to provide radially extending walls that widen at the ends, which also provides for enhanced mechanical strength, and for manufacturability using 3D printing or other additive manufacturing techniques.

According to another aspect of the present disclosure, openings or lattice patterns in the collet ribs may also facilitate circulation of cooling fluid through the weld collet member to decrease the thermal transfer from the workpiece to the fixture block. In one such embodiment, as shown inFIGS.14and14A, an enclosed (e.g., by radial walls1357,1367and non-apertured endmost ribs1355), at least partially hollow collet member1350may include cooling fluid ports1357ain one or both radial end walls1357,1367, positioned to allow for the passage of cooling fluid (e.g., air, nitrogen, argon, water, or other cooling gases or liquids) through openings1360in the ribs1355. In other embodiments, as shown inFIG.15, the ribs may be replaced by, or supplemented with, axially extending reinforcing structures (e.g., reinforcing rods1465, as shown) that provide axial bracing or reinforcement of the collet member1450, while permitting the passage of cooling fluid through the hollow collet member. The selected rib lattice pattern, and/or shape and arrangement of the supporting rods may provide increased surface area for contact with the cooling fluid.

To further facilitate thermal transfer from the collet body to the cooling fluid, the support structure(s) of the collet body intermediate portion (e.g., ribs and/or rods) may be formed from a material having a greater thermal conductivity, compared to the inner and outer wall portions of the collet body. For example, the support structure(s) may be formed with a smaller porosity, or from a greater thermal conductivity metal, such as stainless steel, aluminum and its alloys, copper and its alloys such as brass and bronze, or any suitable material having a higher thermal conductivity (e.g., greater than 20 W/mK), while the inner and outer wall portions may be formed with a greater porosity, or from a smaller thermal conductivity material, such as Hastelloy C and X, Inconel alloy 625 and 718, and Monel alloy 400 and K-500, cobalt-base alloys such as Haynes 25 and CoCr derivatives, or any suitable material having a relatively low thermal conductivity (e.g., less than 20 W/mK).

Additive manufacturing techniques for fabricating collet members, as described herein, may additionally be used to fabricate special, customer specific colleting configurations, for example, without requiring expensive and time-consuming casting processes. These techniques may be used, for example, to produce collet members having alternative geometries. For example,FIGS.6and7each illustrate an exemplary collet member550,650having a modified inner diameter or inner workpiece engaging portion554,654, for example, to provide clearance for a non-cylindrical outer portion of a workpiece (e.g., a flange or other radial extension). In the exemplary embodiment ofFIG.6, a radially extending lip554ais provided to engage the workpiece, providing radial clearance between the lip and the surface of the inner wall portion554. In the exemplary embodiment ofFIG.7, a radially recessed groove654ain the inner wall portion654provides clearance for a radially extending portion of the workpiece. As another example,FIG.8illustrates an exemplary collet member650having a modified outer wall portion752(e.g., with cone shaped extension752a), for example, to axially extend the collet body751to provide an axially extended inner wall portion754without extending the clamping block engaging portion of the outer wall portion. As another example,FIG.9illustrates a collet member850having an inner wall portion854defining a non-cylindrical workpiece engaging surface (as shown, a hex-shaped surface, but other shapes and contours may be provided).FIG.10illustrates a different type of collet member950, having a non-cylindrical outer wall portion952.

The inventive aspects have been described with reference to the exemplary embodiments. Modification and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.