Patent Grant
9346147
The invention relates generally to the field of waterjet cutting systems and processes. More specifically, the invention relates to methods and apparatuses for aligning a water stream within a waterjet cutting head.
Waterjet cutting systems produce high pressure, high-velocity jets of water for cutting materials. These systems typically function by pressurizing water or another suitable fluid to a high pressure (e.g., up to 90,000 pounds per square inch or greater) and forcing the fluid through a small orifice at high velocity to concentrate a large amount of energy on a small area. To cut hard materials, a water jet can be “abrasive” or include abrasive particles within the water jet for increasing cutting ability. As used herein, the term “waterjet” includes any substantially pure water jet, liquid jet, and/or slurry jet. As used herein, the term “pump” means “ultra-high pressure pump” between about 30,000-90,000 pounds per square inch (PSI) or above. However, one of ordinary skill in the art could easily appreciate that the invention also applies to low pressure systems.
During operation of waterjet cutting systems, fluid (e.g., water) is directed to a waterjet orifice assembly for constriction and alignment by the waterjet orifice assembly. The water stream exiting the orifice assembly must be well-aligned to an axis of the waterjet nozzle such that the water stream does not significantly touch the interior wall of the nozzle prior to exiting the cutting head. It is preferable for the water stream to be centered within the nozzle. Poor water stream alignment will cause the nozzle life and cut performance (e.g. cut speed, part tolerance and edge quality) to deteriorate. Currently, orifice assemblies are built by placing an orifice in a cavity of a machined base or housing and then pressing a retaining ring over the orifice to secure the orifice in place. However, using this approach it can be difficult to machine the cavity to the high level of accuracy that is required for excellent alignment of the orifice stream to the axis of the nozzle. Orifice assemblies can also be manufactured by assembling the orifice into a base blank; aligning the water stream exiting the blank; and machining the orifice assembly datum features accordingly to achieve proper alignment. However, this process can be very costly, and it can have difficulty achieving high water stream alignment. What is needed is a well-aligned orifice assembly that can be produced consistently without a costly alignment procedure.
The present invention addresses the unmet need for a waterjet cutting system that achieves high water stream alignment without the need for a costly alignment procedure. In some embodiments, substantial parallelism is introduced between the bottom surface of the base component and the top surface of the orifice in an orifice assembly. In some embodiments, substantial perpendicularity is introduced between the bottom surface of the base component and a longitudinal axis of the base component. In some embodiments, a pedestal-shaped base component protrudes from the top surface of the base component and allows the orifice seating surface to be accessed by equipment capable of grinding the orifice seating surface to be substantially parallel to the bottom surface of the base component.
In some embodiments, the pedestal includes a top surface that protrudes above the rest of the orifice base. A press cap is press fit to the pedestal and shaped to secure the orifice component to the pedestal. In some embodiments, a press cap can be designed with an inner diameter surface which is press fit onto the outer diameter of the pedestal. In some embodiments, the press cap can be designed such that an outer diameter of the press cap contacts an inner surface of a depression in the top surface of the base component. In addition to providing a high degree of parallelism between the orifice seating surface and the bottom surface of the base component, the invention provides improved waterjet cutting performance (e.g. improved cutting speed, part tolerance, and/or edge quality) and consistent production of well-aligned orifice assemblies, without the need for costly alignment procedures.
In one aspect, the invention features an orifice assembly for a liquid jet cutting system. The orifice assembly includes a base having a bottom surface and a top surface. The base defines a base conduit generally parallel to a central axis of the orifice assembly. The top surface includes a planar top region defined by at least a portion of an exterior surface of the base. The planar top region is at least substantially perpendicular to the base conduit. The orifice assembly includes an orifice structure disposed on the planar top region of the top surface of the base. The orifice structure defines an intermediate conduit therethrough. The intermediate conduit is aligned with and in fluid communication with the base conduit. The intermediate conduit is at least substantially perpendicular to the planar top region and parallel to the central axis of the orifice assembly.
In some embodiments, the base is configured to matingly engage an abrasive body. In some embodiments, the base is a cutting head or an abrasive body. In some embodiments, the base conduit comprises a first cylindrical portion and a second cylindrical portion. The first cylindrical portion can have a different diameter than the second cylindrical portion. In some embodiments, a diameter of the base conduit is larger than a diameter of the intermediate conduit. In some embodiments, the top surface comprises a sealing surface. In some embodiments, a pedestal is located within a depression of the top surface. In some embodiments, the base conduit comprises a pedestal section and a base section. The pedestal section can have a smaller diameter than the base section.
In another aspect, the invention features an orifice assembly for a liquid jet cutting system. The orifice assembly includes a generally cylindrical base having a planar bottom region, a central axis and a top surface. The base defines a base conduit generally parallel to the central axis and extending from the top surface to the planar bottom region of the base. The base includes a pedestal defining a protrusion from the top surface of the base. The pedestal has a planar top region substantially parallel to the planar bottom region of the base. The orifice assembly includes an orifice member on the planar top region of the pedestal. The orifice member defines an intermediate conduit therethrough. The intermediate conduit is in fluid communication with the base conduit. The orifice assembly includes an orifice cap. The orifice cap defines an upper conduit therethrough. The orifice cap is configured to secure the orifice member to the pedestal. The upper conduit is in fluid communication with the intermediate conduit of the orifice member.
In some embodiments, the base is configured to matingly engage an abrasive body. In some embodiments, the base is a cutting head or an abrasive body. In some embodiments, the base conduit comprises a first cylindrical portion and a second cylindrical portion. In some embodiments, the first cylindrical portion has a different diameter than the second cylindrical portion. In some embodiments, a diameter of the base conduit is larger than a diameter of the intermediate conduit. In some embodiments, the top surface comprises a sealing surface.
In some embodiments, the pedestal is located within a depression in the top surface. In some embodiments, the base conduit comprises a pedestal section and a base section. In some embodiments, the pedestal section has a smaller diameter than the base section. In some embodiments, the upper conduit has a substantially conical shape. In some embodiments, the orifice cap includes a shaped feature configured to contact a circumferential surface of the orifice member. In some embodiments, the shaped feature is oriented to align the base conduit, the intermediate conduit and the upper conduit.
In some embodiments, the orifice cap comprises titanium. In some embodiments, the orifice cap is press fit on the pedestal about the orifice member. In some embodiments, the orifice cap includes a set of circumferential flanges extending radially inward and connecting to a lip disposed about the pedestal. In some embodiments, a parallelism value for the orifice assembly is about 0.00005 to 0.00015 inches. In some embodiments, the planar bottom region of the base and the planar top region of the pedestal are ground to be at least substantially parallel. In some embodiments, the top surface of the base is rounded. In some embodiments, one or more vent features are included in at least one of the pedestal, the orifice cap or the orifice member.
In another aspect, the invention features a liquid jet cutting system. The liquid jet cutting system includes a fluid pump. The liquid jet cutting system includes a cutting head in fluid communication with the fluid pump. The cutting head includes a cutting head body. The cutting head includes an orifice assembly connected to the cutting head body. The orifice assembly defines a portion of a fluid conduit. The orifice assembly includes a base component connected to the cutting head body. The base component includes a protruding orifice engagement region having a top surface. The base component includes a bottom surface parallel to the top surface. The orifice assembly includes an orifice cap disposed about the protruding orifice engagement region. The orifice assembly includes an orifice component disposed between the orifice cap and the orifice engagement region.
In some embodiments, the orifice cap extends substantially about the orifice engagement region. In some embodiments, the orifice component matingly engages the orifice cap. In some embodiments, the orifice cap comprises titanium. In some embodiments, the base component comprises a sealing surface located circumferentially around the orifice engagement region. In some embodiments, one or more vent features are included in at least one of the pedestal, the orifice component or the orifice cap.
In another aspect, the invention features a base component for a liquid jet cutting head. The base component includes a body portion for connecting to a liquid jet cutting head. The body portion at least partially defines a first segment of a liquid jet conduit and a first circumferential surface of the base component. The base component includes an elevated portion extending axially outward from a sealing surface. The elevated portion at least partially defines a second segment of the liquid jet conduit, a platform, and a second circumferential surface. The platform is substantially parallel to a bottom surface of the base component.
In some embodiments, the first and second segments of the liquid jet conduit have different diameters. In some embodiments, the first segment has a larger diameter than the second segment. In some embodiments, the elevated portion is located in or extends from a depression on the sealing surface of the body portion. In some embodiments, the sealing surface is shaped to engage an adapter and create a seal between the sealing surface and the adapter. In some embodiments, the orifice surface of the platform extends above the sealing surface of the body portion. In some embodiments, the first and second circumferential surfaces define a step feature shaped to connect to an orifice cap. In some embodiments, the elevated portion of the base component has an outer diameter configured to be press fit with a cap having an inner diameter. In some embodiments, the outer diameter of the base component is substantially similar to the inner diameter of the cap.
In another aspect, the invention features a method of assembling a waterjet cutting head. The method includes providing an orifice member that defines a first conduit. The method includes disposing the orifice member on a planar surface of a pedestal that protrudes from a surface of a base component. The base component defines a second conduit that is fluidly coupled to the first conduit. The method includes securing the orifice member to the planar surface of the pedestal by fastening an orifice cap to the pedestal. The orifice cap defines a third conduit fluidly coupled to and substantially aligned with the first and second conduits. In some embodiments, the first, second and third conduits are aligned along a central axis of the waterjet cutting head.
In another aspect, the invention features an orifice cap assembly for a liquid jet cutting system. The orifice cap assembly includes a cap. The cap includes a disk-shaped base portion defining a central axis and having a first bore. The cap includes an adjacent distal sleeve portion oriented orthogonally with respect to the base portion. The cap includes a securing member disposed about a circumference of a distal end of the sleeve. The orifice cap assembly includes an orifice member shaped and configured to be secured within the cap. The orifice member defines a second bore.
In some embodiments, the securing member is a continuous flange. In some embodiments, the securing member comprises a plurality of flanges connected to a circumferential region of the base portion. In some embodiments, the plurality of flanges extends axially outward from the base portion. In some embodiments, the cap includes titanium. In some embodiments, the first bore has a substantially conical shape. In some embodiments, the base portion further includes a set of step features shaped to connect to an orifice component.
The foregoing discussion will be understood more readily from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
Inside the waterjet cutting head 100, the water stream exiting the orifice assembly 104 must be well-aligned to the waterjet nozzle orifice 128. The alignment must be good enough to enable the water stream to pass through the mixing chamber 112 and nozzle 120 without substantially contacting and/or touching the interior wall of the nozzle 120 prior to exiting the cutting head 100. It is preferable for the water stream to be centered within the nozzle 120. Poor water stream alignment will cause the nozzle life and cut performance (e.g. cut speed, part tolerance and edge quality) to deteriorate.
A number of dimensional tolerances of the cutting head can affect the aligment of the water stream within the cutting head. Testing has shown that a critical factor to good water stream alignment is the degree of parallelism between the top surface of the orifice 208 and the bottom surface of the base component 204. “Parallelism” can be quantified as a linear dimension measuring misalignment between two substantially parallel surfaces, e.g. a difference by which the bottom surface of the orifice 208 is misaligned to a contact surface. Since the orifice 208 can be provided with substantially parallel top and bottom surfaces, the water stream alignment is critically dependent on the ability of the bottom surface of the base component (e.g. base component 204) to be parallel to the orifice seating surface (e.g. orifice seating surface 232).
The base component 304 has a planar bottom surface 308, a top surface 312, and a side surface 316. The base conduit 340 can extend from the top surface 312 to the planar bottom surface 308. The planar bottom surface 308 can function as the primary datum to the cutting head (not shown) for the orifice assembly 300. The top surface 312 can include a first portion 313 and/or a second portion 315. The first portion 313 can have a convex and/or rounded shape. The first portion 313 can form a high pressure, metal-to-metal water sealing surface when mated with an adapter of the cutting head (not shown). The second portion 315 can form a recess in the top surface (e.g. in an annulus located between the first portion 313 and the protrusion 324). The recess in the top surface can allow space for the press cap while minimizing the overall length of the orifice assembly, and/or can allow for the use of an adequate length press cap while maintaining a short overall profile, thus economizing on the material used.
The top surface 312 can define a protrusion 324, e.g. a pedestal, orifice structure, etc. The protrusion 324 can have a cylindrical or substantially cylindrical shape (or as depicted in
The planar top surface 328 of the protrusion 324 contacts (e.g. serves as an orifice seating region for) the orifice member 336. The orifice member 336 can have a substantially cylindrical shape (or as shown in
The orifice assembly 300 has a cap 356 (e.g. a press cap). The cap 356 fastens the orifice member 336 to the base component 304. The cap 356 can be press fit onto the base component 304, e.g. onto protrusion 324, an inner diameter of the cap 356 substantially similar to an outer diameter of the protrusion 324. The cap 356 can be made of metal, e.g. Titanium. The cap 356 can have an opening 364 defining an upper conduit in fluid communication with the intermediate conduit 348. The opening 364 can have a substantially conical or frusto-conical shape. When the cap 356 is fastened to the base component 304, empty space or air 360 can exist in between the cap 356, the orifice 336 and the protrusion 324. The protrusion 324 can include a feature 366, e.g. a small cylindrical recess that allows the cap 356 to better grip the protrusion 324. The cap 356 can expand over the protrusion 324 and return to a smaller diameter after passing over the bottom lip of the larger top diameter of the protrusion 324 effectively snapping these components together to prevent the cap 356 from coming off. In some embodiments, the cap 356 includes a shaped feature 370 configured to contact a circumferential surface of the orifice member 336. In some embodiments, the shaped feature 370 can locate the orifice 336 relative to the cap 356 and/or the protrusion 324. In some embodiments, the feature 370 can substantially align the intermediate conduit 348, the opening 364, and the base conduit 340. In some embodiments, the cap 356 includes a set of circumferential flanges extending radially inward and connecting to a lip disposed about the protrusion 324.
In some embodiments, the cap 356 includes a disk-shaped base portion defining a central axis and having a first bore; an adjacent distal sleeve portion oriented orthogonally with respect to the base portion; and a securing member disposed about a circumference of a distal end of the sleeve. In some embodiments, the securing member is a continuous flange. In some embodiments, the securing member comprises a plurality of flanges connected to a circumferential region of the base portion, the plurality of flanges extending axially outward from the base portion. In some embodiments, the base portion includes a set of step features shaped to connect to the orifice component (e.g., protrusion 324).
The base component 304 can be composed of metal, e.g. stainless steel. The base component 304 can have a diameter of about 0.125″ to 0.5″ or greater, e.g. about 0.436″. In some embodiments, the base component 304 is configured to matingly engage an abrasive body. In some embodiments, the base component 304 is a cutting head or an abrasive body. Standalone orifices can be produced to very tight parallelism specifications, such that any deviation is a very small contributor to the overall parallelism of the orifice assembly. The orifice can have a major diameter of about 0.070″. The outer diameter of the protrusion 324 (and/or inner diameter of the cap 356) can be about 0.100″.
The invention also includes a method of assembling a waterjet cutting head. The method includes providing an orifice member (e.g. the orifice member 336 as shown above in
Table 1 shows exemplary data collected using a coordinate measuring machine (CMM) system for several orifice components in accordance with the current invention. In this case, the “parallelism” value represents the distance (measured in inches) at the pedestal's outer diameter of 0.100 inches by which the surface is misaligned relative to the orifice component's bottom surface. In other words, one side of the pedestal's outer diameter is further from the bottom surface of the orifice component than the opposite side of the pedestal's outer diameter by the parallelism value. Comparative data are provided for orifice assembly bases that are both “ground” and “machined.” As is evident from Table 1, the parallelism value is much lower (e.g. the surfaces are closer to being parallel) for the ground parts: the average parallelism value for the “ground” orifice components is 0.00008 inches, with a standard deviation of 0.00004 inches; while the average parallelism value for the “machined” orifice components is 0.00027 inches, with a standard deviation of 0.00012 inches.
Table 2 shows stream alignment data that compares benchmark or existing style orifice assemblies to several pedestal style orifice assemblies for diameters of 0.012 inches and 0.013 inches. Eight 0.012 inch diameter pedestal style orifice assemblies and four 0.013 inch diameter pedestal style orifice assemblies were tested for flow rate, stream quality and alignment as compared to the prior art part designs. The numerical values in the “Alignment” column provide a metric for easily quantifying the amount of time for which the stream was aligned, and can be understood as follows: −1 represents no lineup of water in the inlet; 0 represents no lineup of water coming out of the nozzle; 1 represents an alignment of water coming out of the nozzle for 1 second or less; 2 represents an alignment of water coming out of the nozzle for 5 seconds or less; and 3 represents an alignment of water coming out of the nozzle for over 5 seconds. Thus, a higher number is correlated with a longer alignment time and thus a better-aligned assembly. As Table 2 shows, flow rates and stream quality were comparable for all parts, but alignment was significantly better using the ground pedestal.
1The Stream Quality Nut measures the coherent length of the stream from the face of the water-only nut.
2The Stream Lineup codes are similar to those show above in Table 2: 0 represents no stream lineup; 1 represents stream alignment for 1 second or less; 2 represents stream alignment for 5 seconds or less; 3 represents stream alignment for over 5 seconds.
3Diamonds are existing stock and are used as a benchmark.
Table 3 shows test data comparing parts from existing orifice assemblies and the pedestal style orifice assemblies. Results are included for both 0.010″ and 0.014″ diameter orifices. The results indicate good stream quality for all orifice assemblies tested. The water-only cohesive length was measured to be slightly longer for the benchmark parts. The stream line-up results were slightly better for the pedestal orifice assemblies than the benchmark parts. The pedestal 0.014″ diameter orifice assemblies showed good alignment even to a 0.030″ nozzle. All of the parts tested passed the cycle test. During testing, all of the pedestal style orifice assemblies had acceptable alignment test results. These pedestal parts were made without the added expense of an alignment step during manufacturing.
As used herein, it is understood that the term “planar” can also refer to a plane defined by three or more contact points with a contacting surface and/or seat. For example, a ring or raised “rim” can define a plane of a “planar” surface. While the invention has been particularly shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the following claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5199640 | Ursic | Apr 1993 | A |
| 6715701 | Julien | Apr 2004 | B1 |
| 20050252352 | Tateiwa | Nov 2005 | A1 |
| Entry |
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| International Search Report and Written Opinion in corresponding application PCT/US2015/029346, Jul. 29, 2015, 12 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20150321315 A1 | Nov 2015 | US |
