WO2014099401A1

WO2014099401A1 - Workpiece fixture of fluid jet cutting system

Info

Publication number: WO2014099401A1
Application number: PCT/US2013/073401
Authority: WO
Inventors: Mohamed A. Hashish; Steven J. Craigen; Bruce M. Schuman
Original assignee: Flow International Corporation
Priority date: 2012-12-17
Filing date: 2013-12-05
Publication date: 2014-06-26

Abstract

A workpiece fixture assembly is provided to support a workpiece to be processed by a fluid jet cutting system. The workpiece fixture assembly includes a main support structure having at least one exterior portion and at least one interior portion separated by a tool path corridor and includes at least one supplemental support structure rigidly coupling the at least one exterior portion of the main support structure to the at least one interior portion of the main support structure and spanning beneath the tool path corridor at one or more crossing locations. A device is also provided beneath the main support structure to aid in preventing contents of a fluid jet from rebounding toward the main support structure after passing through the tool path corridor thereof during a workpiece processing operation.

Description

WORKPIECE FIXTURE OF FLUID JET CUTTING SYSTEM

BACKGROUND

Technical Field

This disclosure generally relates to workpiece support fixtures usable with fluid jet cutting systems.

Description of the Related Art

High-pressure fluid jets, including high-pressure abrasive waterjets, are used to cut a wide variety of materials in many different industries. Systems for generating high-pressure waterjets and abrasive waterjets (collectively "waterjets") are currently available, such as, for example, the Mach 4™ 5 axis waterjet system manufactured by Flow International Corporation, the assignee of the present invention. Other examples of waterjet cutting systems are shown and described in Flow's U.S. Pat. No. 5,643,058, which is incorporated herein by reference in its entirety. In such systems, high- pressure fluid, typically water, flows through an orifice in a cutting head to form a high-pressure jet, into which abrasive particles can be combined as the jet flows through a mixing tube to form a high-pressure abrasive waterjet. The high-pressure abrasive waterjet is discharged from the mixing tube and directed toward a workpiece to cut the workpiece along a designated path. In other instances, abrasives may not be introduced and a pure waterjet may be discharged from a nozzle toward a workpiece to cut the workpiece along a designated path without the aid of abrasives.

Workpieces are generally supported on a platform (commonly formed of a series of slats) or held by a fixture for processing by the high- pressure jet. During processing of the workpiece, some energy of the high- pressure jet is absorbed by the workpiece itself while other energy is typically absorbed by a volume of water underlying the workpiece. A catcher tank is typically provided to hold water for this purpose. Conventional catcher tanks often include a workpiece platform (commonly formed of a series of slats) on which to position a workpiece to be processed. Clamp devices or fixture devices may couple the workpiece to the platform to hold the workpiece in place while it is processed. Conventional fixtures, however, can suffer from a variety of drawbacks, including subjecting the workpiece to frosting or other damage arising from rebounding contents of the fluid jet after it cuts through a workpiece.

BRIEF SUMMARY

Embodiments described herein provide workpiece fixture assemblies that are configured to support a workpiece between the working end of a fluid jet cutting machine (e.g., a cutting head or nozzle) and a catcher tank or other receptacle for collecting the contents of the fluid jet after is passes through the workpiece during processing operations. The workpiece fixture assemblies are configured to support workpieces in a manner that substantially prevents, minimizes or eliminates contents of the fluid jet from rebounding and impinging on the workpiece after passing therethrough. Additionally, the workpiece fixture assemblies may significantly suppress, dampen or muffle noise generated during workpiece processing operations.

In one embodiment, a workpiece fixture assembly for a waterjet cutting system may be summarized as including: a main support structure having at least one exterior portion and at least one interior portion separated by a tool path corridor; at least one supplemental support structure rigidly coupling the at least one exterior portion of the main support structure to the at least one interior portion of the main support structure and spanning beneath the tool path corridor at one or more crossing locations, the at least one supplemental support structure including a void beneath the tool path corridor at the one or more crossing locations; and a device provided beneath the main support structure to aid in preventing contents of a fluid jet from rebounding toward the main support structure after passing through the tool path corridor thereof during a workpiece processing operation. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Figure 1 is an isometric view of a waterjet cutting system.

Figure 2 is an isometric view of a workpiece fixture assembly, according to one embodiment, with a workpiece supported thereon shown transparent to reveal underlying structures.

Figure 3 is an isometric view of the workpiece fixture assembly of Figure 2 with the workpiece supported thereon shown opaque.

Figure 4 is a side elevational view of the workpiece fixture assembly of Figure 2 shown with a vacuum system.

Figure 5 is a cross-sectional view of the workpiece fixture assembly of Figure 2 taken along line 5-5.

Figure 6 is a partial detail view of the cross-section of the workpiece fixture assembly shown in Figure 5.

Figure 7 is an isometric view of a workpiece fixture assembly, according to another embodiment, with a pair of workpieces supported thereon.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one of ordinary skill in the relevant art will recognize that

embodiments may be practiced without one or more of these specific details. In other instances, well-known structures associated with waterjet systems and workpiece fixture assemblies may not be shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments. For instance, it will be appreciated by those of ordinary skill in the relevant art that a high-pressure fluid source and an abrasive source may be provided to feed high-pressure fluid and abrasives, respectively, to a cutting head of the waterjet system to facilitate high-pressure abrasive waterjet cutting of workpieces supported by the workpiece fixture assemblies described herein. As another example, well know control systems and drive components may be integrated into the waterjet cutting system to facilitate movement of the cutting head relative to the disclosed workpiece fixture assemblies and hence workpieces to be processed.

Unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense, that is as "including, but not limited to."

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

Embodiments described herein provide workpiece fixture assemblies that are configured to support a workpiece between the working end of a fluid jet cutting machine (e.g., a cutting head or nozzle) and a catcher tank or other receptacle for collecting the contents of the fluid jet after is passes through the workpiece during a processing operation. The workpiece fixture assemblies are configured to support workpieces in a manner that substantially prevents, minimizes or eliminates contents of the fluid jet from rebounding and impinging on the workpiece after passing therethrough. Additionally, the workpiece fixture assemblies may significantly suppress, dampen or muffle noise generated during workpiece processing operations.

Figure 1 shows an example embodiment of a fluid jet cutting system 10. The fluid jet cutting system 10 includes a catcher tank assembly 12 that is configured to assist in supporting a workpiece 14 to be processed by the system 10 while also serving as a receptacle to collect the contents of the discharged fluid jet. For instance, a workpiece 14 may be positioned on or clamped to a platform16 defined by the catcher tank assembly 12 for

subsequent processing. The waterjet cutting system 10 further includes a bridge assembly 18, which is movable along a pair of base rails 20 and straddles the catcher tank assembly 12. In operation, the bridge assembly 18 moves back and forth along the base rails 20 with respect to a translational axis X to position a cutting head 22 of the system 10 for processing the workpiece 14. A tool carriage 24 is movably coupled to the bridge assembly 18 to translate back and forth along another translational axis Y, which is aligned perpendicularly to the translational axis X. The tool carriage 24 is further configured to raise and lower the cutting head 22 along yet another translational axis Z to move the cutting head 22 toward and away from the workpiece 14. An articulated wrist 26 may be provided to adjust an orientation of the cutting head 22 relative to the workpiece 14 to enable processing of the workpiece 14 along particularly complex tool paths and tool orientations.

During operation, movement of the cutting head 22 with respect to each of the translational axes X, Y, Z and axes of the articulated wrist 26 may be accomplished by various conventional drive components and an appropriate control system 28. A waste removal system 30 may be coupled to the catcher tank assembly 12 to receive and process waste collected from the interior of the catcher tank assembly 12 during operation. Other well know systems

associated with waterjet cutting machines may also be provided such as, for example, a pump for supplying high-pressure fluid to the cutting head 22 and/or an abrasive hopper for feeding abrasives to the cutting head 22 to enable abrasive waterjet cutting. These other well known systems, however, are not shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments.

Figures 2 through 6 show one example embodiment of a workpiece fixture assembly 40 which may be used to support a workpiece 42 while the workpiece 42 is being processed by a fluid jet cutting system, such as, for example, the fluid jet cutting system 10 shown in Figure 1 . More

particularly, the workpiece fixture assembly 40 may be positioned between the platform 16 of the catcher tank assembly 12 and the cutting head 22 of the fluid jet cutting system 10, which may be manipulated in space above the catcher tank assembly 12 along a designated tool path to process the workpiece 42. In some instances, the workpiece fixture assembly 40 may be configured as mobile, self-contained unit that may be readily positioned on the platform 60 of a catcher tank assembly 12 or other support system. In some instances, the workpiece fixture assembly 40 may be positioned within the range of motion of a fluid jet cutting head coupled to other known motion systems, such as, for example, a fluid jet cutting head coupled to a multi-axis robotic arm.

With reference to Figure 2, the workpiece fixture assembly 40 includes a main support structure 44, such as a steel plate structure, having a tool path corridor 46 that separates the main support structure 44 into separate portions. In particular, the tool path corridor 46 separates the main support structure 44 into an exterior support portion 48 and an interior support portion 50. The tool path corridor 46 tracks a desired cut path of the workpiece 42 to be processed and provides clearance for contents of the impinging fluid jet to pass through the main support structure 44 unobstructed. In the example embodiment shown in Figures 2 through 6, the workpiece 42 is shown as having a generic, planar structure in a generally rectangular shape and the desired cut path is shown as having a similar rectangular profile. It is

appreciated, however, that workpieces 42 may take on a variety of different forms and the desired cut path may comprise numerous regular and irregular profiles. In addition, the main support structure 44 may be divided into three, four or more separate regions by two or more intersecting or non-intersecting tool path corridors 46.

With reference to Figures 2 through 4, the workpiece fixture assembly 40 further includes a pair of supplemental support structures 52 which rigidly couple the exterior portion 48 of the main support structure 44 to the interior portion 50 of the main support structure 44 and which span beneath the tool path corridor 46 at one or more crossing locations 54. The

supplemental support structures 52 may comprise, for example, offset plate structures that extend across a width of the main support structure 44 and abut the main support structure 44 on each of opposing sides of the tool path corridor 46, as shown best in Figures 5 and 6. As shown best in Figure 6, each supplemental support structure 52 may be rigidly fastened to the main support structure 44 with fasteners 56 on opposing sides of the tool path corridor 46. Alignment pins 58 or other alignment features may also be provided to assist in aligning the supplemental support structures 52 with the main support structure 44 during assembly. It will be appreciated by those of ordinary skill in the relevant art, however, that the main support structure 44 may be coupled to the supplemental support structures 52 by other devices or methods, such as welding the components together, or main be integrally formed, such as, for example, by a casting process.

With reference to Figures 5 and 6, each of the supplemental support structures 52 include voids 60 that are positioned such that the voids 60 lie beneath the tool path corridor 46 at the aforementioned crossing locations 54. The voids 60 may comprise, for example, elongated slots or other apertures that extend downwardly from the main support structure 44. A depth of the voids 60 may be selected to substantially prevent contents of the fluid jet from rebounding off the supplemental support structures 46 and impinging on the main support structure 44 and workpiece 42 supported thereon when the fluid jet passes through the voids 46 during processing of the workpiece 42, or from significantly eroding the supplemental support structures 46. The depth of the voids 60 may be dependent on a number of factors including, for example, the operating pressure of the fluid jet cutting system. A width of the voids 60 in the vicinity of the main support structure 44 may be at least as wide as that of the tool path corridor 46, and in some instances, may be significantly greater than the tool path corridor 46 to create a stepped cavity extending downward from an upper support surface 62 of the main support structure 44, as shown best in Figure 6.

With reference back to Figures 2 through 4, the workpiece fixture assembly 40 further includes a device 70 provided beneath the main support structure 44 to aid in preventing contents of the fluid jet from rebounding toward the main support structure 44 after passing through the tool path corridor 46 thereof during a workpiece processing operation. Advantageously, the device 70 may also significantly suppress, dampen or muffle noise generated during workpiece processing operations. The device 70 may include a filler or sacrificial material 72, such as, for example, a block of open cell foam (as shown in Figures 2 through 6), a honeycomb or honeycomb-type structure, or other like structure. As shown in Figures 2 through 4, the filler or sacrificial material 72 may be provided in block form and may be supported in a manner to substantially fill all of a space immediately beneath the main support structure 44 on opposing sides of the tool path corridor 46. In some

embodiments, the filler or sacrificial material 72 may substantially fill all of a space immediately beneath the main support structure 44 on opposing sides of the tool path corridor 46 for at least a depth of three, four or more inches. In some embodiments, the device 70 may include a filler material 72 having preformed channels, passages or cavities that align with the tool path corridor 46 to enable the fluid-jet to pass through the filler material 72 unobstructed. In other embodiments, the device 70 may include a sacrificial material 72 that may be cut or otherwise eroded by the fluid jet during one or more processing operations.

With reference to Figures 4 and 5, the device 70 may include a support system 74 that is configured to support the filler or sacrificial material 72 in position beneath the main support structure 46. The support system 74 may comprise, for example, an array of elongated support members 76 (e.g., round stock, flat stock, tubing, etc.) that pass through the supplemental support structures 52 and hold the filler or sacrificial material 72 between the elongated support members 76 and the main support structure 44. In some embodiments, the support system 74 may support the filler or sacrificial material 72 to be in direct or abutting contact with the main support structure 44. In other instances, a gap may be provided between the main support structure 44 and the filler or sacrificial material 72. The support system 74 may further include a plurality of fender washers 78 and bolts 80 or other suitable fasteners to contain the filler or sacrificial material 72 in position laterally. The supplemental support structures 52 and the elongated support members 76 may include tapped holes, through holes, or other features for receiving such fasteners.

The device 70 may further include a biasing system (not shown) configured to apply a bias to the filler or sacrificial material 72 to compress the filler or sacrificial material 72 after a portion of the material 72 is eroded by the fluid jet. For example, a spring element may be arranged to apply a side load to the filler or sacrificial material 72 and urge the material against a stop. In some instances, spring elements, actuators or other biasing devices may be provided on opposing sides on the filler or sacrificial material 72 to bias the material inwardly. The biasing system may collapse cavities that form as the fluid jet erodes the filler or sacrificial material 72 during use.

With reference to Figure 4, the workpiece fixture assembly 40 may further include a vacuum system 90 operatively coupled to the main support structure 44 to assist in retaining the workpiece 42 in position on the main support structure 44 by creating a vacuum beneath the workpiece 42. The vacuum system 90 may be operatively coupled to the exterior support portion 48 of the main support structure 44 and the interior support portion 50 of the main support structure 44. In this manner, a vacuum may be established to hold each of the separate pieces of the workpiece 42 that remain after cutting or trimming the workpiece 42 (see, e.g., Figure 3, which shows a central portion 42a of the workpiece 42 separated from an outer portion of the workpiece 42b by a cut 43 that has been formed in the workpiece 42 by the fluid jet system). The vacuum system 90 may further include passages or conduits 92 that interface with the main support structure 44 and are connected to a vacuum source 94. In some instances, the passages or conduits may be routed to pass through the device 70.

In some embodiments, the workpiece fixture assembly 40 may include other attachment mechanisms in lieu of the vacuum system 90 for holding the workpiece 42 in place during processing operations. For example, clamps or other fasteners may secure the workpiece 42 to the main support structures 42.

In some embodiments, the main support structure 44 may be provided with locating pins or other locating features to receive and accurately position the workpiece 42 thereon. The locating pins or other locating features may retain the workpiece 42 in position laterally during processing operations.

Although the example embodiment of the workpiece fixture assembly 40 shown in Figures 2 through 6 includes a main support structure 44 having a single tool path corridor 46 with a closed profile, it is appreciated that in some embodiments, the main support structure 44 may include more than one tool path corridor 46, such as, for example, when additional interior cuts may be desired in the workpiece 42. In addition, each of the one or more tool path corridors may follow a three-dimensional path over a workpiece having a complex surface or surfaces.

Moreover, with reference to Figure 7, a workpiece fixture assembly 40' may be provided with a series of processing regions 96, 98 to support multiple workpieces 42 to be processed sequentially or simultaneously with a waterjet system comprising multiple cutting heads. The processing regions 96, 98 may be provided in a linear array or may be otherwise spaced in regular or irregular intervals. Each processing region 96, 98 includes one or more tool path corridors (not visible) which correspond to a desired cut path, as well as other features described above, to provide a fixture arrangement which is well suited to enable the processing of workpieces in a manner that reduces noise pollution and protects the workpieces 42 from rebounding fluid jet contents. Example workpieces 42 may be made of metal, composite or other materials and may include a plurality of separate internal shapes and an outer trim path that can be cut using a suitable fluid jet system. For example, in the case of a composite component, a waterjet having approximately a 0.005 inch diameter may be used at pressures ranging from about 40,000 psi to about 90,000 psi or more to cut the desired profiles. The workpiece fixture assembly for supporting such a workpiece may be made out of aluminum and include corresponding tool path corridors for cutting the separate internal shapes and outer trim path. The workpiece fixture assembly may further include voids at the crossing locations having a depth from the main support structure in the range of about one inch to about five inches, for example. The total depth of the support fixture may be in the range of about two inches to about six inches.

The final component and the remnants from the internal shapes can be held in position by vacuum or other devices to avoid interfering with cutting operations. However, in instances where the remnants may be particularly small or slender, the remnants may be allowed to fall through the workpiece fixture assembly. In this case, the filler or sacrificial material can include passages therethrough to allow the small or slender remnants to fall through if the filler or sacrificial material is provided with sufficient depth to minimize or eliminate the occurrence of fluid jet contents from rebounding toward the workpiece through the passages. An example depth that may be needed for the filler or sacrificial material is about four inches for a cutout width of about 0.2 inches.

The various embodiments described above can be combined to provide further embodiments. In addition, one of ordinary skill in the relevant art will recognize that embodiments may be practiced without one or more of the specific details shown and described above. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.

U.S. Patent Application No. 61/738,029, filed December 17, 2012 is incorporated herein by reference in its entirety.

Claims

1 . A workpiece fixture assembly for use with a fluid jet cutting system, the workpiece fixture assembly comprising:

a main support structure having at least one exterior portion and at least one interior portion separated by a tool path corridor;

at least one supplemental support structure rigidly coupling the at least one exterior portion of the main support structure to the at least one interior portion of the main support structure and spanning beneath the tool path corridor at one or more crossing locations, the at least one supplemental support structure including a void beneath the tool path corridor at the one or more crossing locations; and

a device provided beneath the main support structure to aid in preventing contents of a fluid jet from rebounding toward the main support structure after passing through the tool path corridor thereof during a workpiece processing operation.

2. The workpiece fixture assembly of claim 1 wherein the device includes a material comprising at least one of a block of open cell foam and a honeycomb structure.

3. The workpiece fixture assembly of claim 2 wherein the material is a sacrificial material.

4. The workpiece fixture assembly of claim 2 wherein the material fills substantially all of a space beneath the main support structure on opposing sides of the tool path corridor for at least a depth of two inches.

5. The workpiece fixture assembly of claim 1 wherein the device comprises a filler or sacrificial material and a biasing system configured to apply a bias to the filler or sacrificial material to compress the filler or sacrificial material after a portion of the filler or sacrificial material is eroded by the fluid jet.

6. The workpiece fixture assembly of claim 1 wherein the main support structure has at least two distinct interior portions, each interior portion bounded by a respective tool path corridor.

7. The workpiece fixture assembly of claim 1 comprising a plurality of supplemental support structures rigidly coupling the at least one exterior portion of the main support structure to the at least one interior portion of the main support structure, each of the plurality of supplemental support structures spanning beneath the tool path corridor at a plurality of crossing locations.

8. The workpiece fixture assembly of claim 1 wherein the void in the at least one supplemental support structure extends beneath the tool path corridor to a depth sufficient to substantially prevent contents of the fluid jet from rebounding to the main support structure when the fluid jet passes through the void during the workpiece processing operation.

9. The workpiece fixture assembly of claim 1 , further comprising:

a vacuum system operatively coupled to the main support structure to assist in retaining a workpiece in position on the main support structure by creating a vacuum beneath the workpiece.

10. The workpiece fixture assembly of claim 9 wherein the vacuum system is operatively coupled to the at least one interior portion of the main support structure and the at least one exterior portion of the main support structure.

1 1 . The workpiece fixture assembly of claim 9 wherein the vacuum system includes conduits that are coupled to the main support structure and pass through the device.