Patent Grant
9050704
This disclosure relates to abrasive-delivery apparatuses for use with abrasive materials in abrasive-jet systems and related apparatuses, systems, and methods.
Abrasive jet systems are used in precision cutting, shaping, carving, reaming, and other material-processing applications. During operation, abrasive jet systems typically direct a high-speed jet of fluid (e.g., water) toward a workpiece to rapidly erode portions of the workpiece. Abrasive material can be added to the fluid to increase the rate of erosion. When compared to other material-processing systems (e.g., grinding systems, plasma-cutting systems, etc.), abrasive jet systems can have significant advantages. For example, abrasive jet systems often produce relatively fine and clean cuts, typically without heat-affected zones around the cuts. Abrasive-jet systems also tend to be highly versatile with respect to the material type of the workpiece. The range of materials that can be processed using abrasive jet systems includes very soft materials (e.g., rubber, foam, leather, and paper) as well as very hard materials (e.g., stone, ceramic, and hardened metal). Furthermore, in many cases, abrasive jet systems can execute demanding material-processing operations while generating little or no dust or smoke.
In a typical abrasive-jet system, a pump pressurizes a fluid to a high pressure (e.g., 275 meganewtons/square meter (40,000 pounds/square inch) to 689 meganewtons/square meter (100,000 pounds/square inch) or more). Some of this pressurized fluid is routed through a cutting head that includes an orifice element having an orifice. Passing through the orifice converts static pressure of the fluid into kinetic energy, which causes the fluid to exit the cutting head as a jet at high speed (e.g., up to 762 meters/second (2,500 feet/second) or more) and impact a workpiece. The orifice element can be a hard jewel (e.g., a synthetic sapphire, ruby, or diamond) held in a suitable mount. In many cases, a jig supports the workpiece. The jig, the cutting head, or both can be movable under computer or robotic control such that complex processing instructions can be executed automatically.
Some conventional abrasive-jet systems mix abrasive material and fluid to form slurry before forming the slurry into a jet. This approach can simplify achieving consistent and reliable incorporation of the abrasive material into the jet, but can also cause excessive wear on internal system components as the slurry is pressurized and then formed into the jet. In an alternative approach, abrasive material is mixed with a fluid after the fluid is formed into a jet (e.g., after the fluid passes through an orifice). In this approach, the Venturi effect associated with the jet can draw the abrasive material into a mixing region along a flow path of the jet. When executed properly, this manner of incorporating abrasive material into a jet can be at least partially self-metering. For example, replenishment of abrasive material in the mixing region can automatically match consumption of abrasive material in the mixing region. The equilibrium between replenishment and consumption, however, can be sensitive to variations in the source of the abrasive material upstream from the mixing region. In at least some cases, conventional apparatuses that convey abrasive materials within abrasive jet systems insufficiently facilitate consistent and reliable delivery of abrasive materials to cutting heads. This can lead to variability in incorporation of the abrasive materials into fluid jets passing through the cutting heads, which, in turn, can cause skip cutting in metals, cracking and chipping in glass, delamination in composites, and/or other undesirable material-processing outcomes.
Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on illustrating clearly the principles of the present technology. For ease of reference, throughout this disclosure identical reference numbers may be used to identify identical or at least generally similar or analogous components or features.
Specific details of several embodiments of the present technology are disclosed herein with reference to
In many applications, the diameter of a fluid jet may be relatively small (e.g., from about 76 microns (0.003 inch) to about 250 microns (0.01 inch)). This can be the case, for example, in abrasive jet systems configured for material-processing operations on a small scale (e.g., micromachining applications, among others). A small-diameter fluid jet typically produces a relatively weak Venturi effect. The same can be true for relatively low-speed fluid jets (e.g., a low-speed fluid jet produced by reducing fluid pressure upstream from a jet orifice, such as to facilitate piercing delicate materials). A relatively weak Venturi effect can complicate consistent and reliable incorporation of an abrasive material into a fluid jet. Vacuum assistance can be used to at least partially address this problem. For example, a vacuum generating device can be operably connected to a cutting head in an abrasive-jet system via a vacuum line and used to provide negative pressure to the cutting head so as to supplement a relatively weak Venturi effect. Vacuum assistance, however, can be challenging to control. For example, vacuum assistance can interfere with equilibrium between replenishment and consumption of abrasive material within a mixing region of a cutting head, leading to inconsistent incorporation of the abrasive material into a fluid jet passing through the cutting head. Furthermore, vacuum generating devices tend to be bulky and vacuum lines extending between such devices and cutting heads can undesirably restrict movement of the cutting heads (e.g., relative to workpieces).
When producing small-diameter fluid jets, low-speed fluid jets, and in other applications, it is often advantageous (or even necessary in some cases) to use fine particulate abrasive materials. For example, in an abrasive-jet system including a cutting head configured to produce a small-diameter fluid jet, abrasive particles of a suitable abrasive material can have an average sieve diameter less than about 40% (e.g., less than about 35%, less than about 30%, or below another suitable threshold percentage) of an inner diameter of an exit tube downstream from a mixing region within the cutting head. Such abrasive particles can reduce or prevent clogging (e.g., due to bridging of abrasive particles within the cutting head). The use of fine particulate abrasive materials can also be necessary or desirable in other applications, such as applications that call for reduced surface roughness around a cut. Unfortunately, fine particulate abrasive materials, alone or in conjunction with small-diameter and/or low-speed fluid jets, can be more challenging to consistently and reliably convey to a cutting head than coarse particulate abrasive materials. Many undesirable flow characteristics (e.g., clumping and rat-hole formation, among others) tend to be more pronounced with fine particulate abrasive materials than with coarse particulate abrasive materials. By way of theory, and not to limit the scope of the present disclosure, at least some undesirable flow characteristics of conventional particulate abrasive materials may be related to friction between constituent abrasive particles. This particle-to-particle friction can have proportionally more influence on the behavior of particulate abrasive materials as the size of the abrasive particles decreases. Thus, in abrasive jet systems having miniature exit tubes and/or abrasive jet systems in which the use of fine particulate abrasive materials is otherwise necessary or desirable, feeding such abrasive materials consistently and reliably to a cutting head can be technically challenging.
Abrasive-delivery apparatuses configured in accordance with at least some embodiments of the present technology can at least partially overcome one or more of the disadvantages and technical challenges discussed above and/or one or more other disadvantages and/or technical challenges associated with conventional abrasive-jet technology. For example, abrasive-delivery apparatuses configured in accordance with at least some embodiments of the present technology can have one or more shapes, angles, other geometrical features, and/or other non-geometrical features that enhance the consistency and/or reliability of flowing fine particulate abrasive materials by gravity relative to at least some conventional abrasive-delivery apparatuses. This can reduce or eliminate the need for vacuum assistance. In a particular example, an abrasive-delivery apparatus configured in accordance with an embodiment of the present technology includes multiple funnel segments (e.g., two, three, four or a greater number of funnel segments) having successively steeper tapers along a downward path along which abrasive material flows by gravity. In at least some cases, particulate abrasive materials (e.g., fine particulate abrasive materials) can flow more consistently, more reliably, and/or at a faster rate through the abrasive-delivery apparatus than through abrasive-delivery apparatuses having only one funnel segment. Furthermore, instead of or in addition to this advantage, the abrasive-delivery apparatus can have other advantages relative to conventional abrasive-delivery apparatuses. Such advantages, for example, may apply to the use of fine particulate abrasive materials and/or to the use of coarse particulate abrasive materials.
Fine particulate abrasive materials can include abrasive particles having an average sieve diameter, for example, of about 50 microns (1969 microinches) or less (e.g., within a range from about 5 microns (197 microinches) to about 50 microns (1969 microinches), within a range from about 5 microns (197 microinches) to about 35 microns (1378 microinches), within a range from about 5 microns (197 microinches) to about 25 microns (984 microinches), or within another suitable range). Coarse particulate abrasive materials can include abrasive particles having an average sieve diameter, for example, of about 50 microns (1969 microinches) or more (e.g., within a range from about 50 microns (1969 microinches) to about 150 microns (5906 microinches), within a range from about 50 microns (1969 microinches) to about 100 microns (3937 microinches), within a range from about 50 microns (1969 microinches) to about 75 microns (2953 microinches), or within another suitable range). Abrasive-delivery apparatuses configured in accordance at least some embodiments of the present technology can be well suited for use with relatively fine abrasive particles and/or relatively coarse abrasive particles. Furthermore, abrasive-delivery apparatuses configured in accordance with at least some embodiments of the present technology can be configured for use with coated and/or uncoated abrasive particles. Additional details regarding suitable abrasive materials are included in U.S. Provisional Patent Application No. 61/801,823, filed Mar. 15, 2013, which is incorporated herein by reference in its entirety.
The abrasive-delivery apparatus 100 can further include a first support member 110 within the housing 102 configured to at least partially support the funnel 104 by contacting the first funnel segment 106, and a second support member 112 within the housing 102 configured to at least partially support the funnel 104 by contacting the second funnel segment 108. In some embodiments, the first and second support members 110, 112 are configured to prevent or reduce lateral and downward movement of the funnel 104 relative to the housing 102, but to allow upward movement of the funnel 104 relative to the housing 102, such as to allow the funnel 104 to be removed from the housing 102 upwardly for servicing and/or replacement. The first support member 110 can be a single annular element or a group of two or more separate bridging elements circumferentially spaced apart and extending radially from an outer surface 106a of the first funnel segment 106 to an inner surface 102c of the housing 102. Similarly, the second support member 112 can be a single annular element or a group of two or more separate bridging elements circumferentially spaced apart and extending radially from an outer surface 108a of the second funnel segment 108 to the inner surface 102c of the housing 102. In some embodiments, the first and second support members 110, 112 are secured (e.g., fixedly or detachably secured) to the inner surface 102c of the housing 102 and not secured (e.g., releasably abutting) the outer surfaces 106a, 108a, respectively, of the first and second funnel segments 106, 108, respectively.
The first funnel segment 106 can include a first inlet 114 and a first outlet 116. The first outlet 116 can be downstream from the first inlet 114 and further from the upper end portion 102a of the housing 102 than the first inlet 114. Similarly, the second funnel segment 108 can include a second inlet 118 and a second outlet 120. The second outlet 120 can be downstream from the second inlet 118 and further from the upper end portion 102a of the housing 102 than the second inlet 118. A first interior region 122 of the first funnel segment 106 can extend between the first inlet 114 and the first outlet 116, and a second interior region 124 of the second funnel segment 108 can extend between the second inlet 118 and the second outlet 120. The first and second interior regions 122, 124 can be inwardly tapered (e.g., monotonically tapered) in a direction extending from the upper end portion 102a of the housing 102 toward the lower end portion 102b of the housing 102. Due to the taper of the first interior region 122, a cross-sectional area and a diameter (D1) of the first inlet 114 perpendicular to a vertical axis 126 is greater than a cross-sectional area and a diameter (D2) of the first outlet 116 perpendicular to the vertical axis 126. Similarly, due to the taper of the second interior region 124, a cross-sectional area and a diameter (D3) of the second inlet 118 perpendicular to the vertical axis 126 is greater than a cross-sectional area and a diameter (D4) of the second outlet 120 perpendicular to the vertical axis 126. In some embodiments, D2 is equal to D3. In other embodiments, D2 is not equal to D3, such as to form a step or overhang at the junction 109. Furthermore, the transition can be rounded to provide a smooth transition from the from the interior surface 106b of the first funnel segment 106 to the interior surface 108b of the second funnel segment 108 at the junction 109.
One or more aspects of the geometry of the first and second interior regions 122, 124 can be selected to enhance the consistency and/or reliability of flowing fine particulate abrasive material under gravity. In some embodiments, the first interior region 122 has a first inward taper toward the first outlet 116, the second interior region 124 has a second inward taper toward the second outlet 120, and the second inward taper is steeper than the first inward taper when the abrasive-delivery apparatus 100 is vertically oriented. The first interior region 122 can have a height H1 along the vertical axis 126 and a diameter (D5) perpendicular to the vertical axis 126 at a midpoint (M1) along H1 between the first inlet 114 and the first outlet 116 when the abrasive-delivery apparatus 100 is vertically oriented. In some embodiments, H1 is at least about one times D5. In other embodiments, H1 can have another suitable value relative to D5. The second interior region 124 can have a height H2 along the vertical axis 126 and a diameter (D6) perpendicular to the vertical axis 126 at a midpoint (M2) along H2 between the second inlet 118 and the second outlet 120 when the abrasive-delivery apparatus 100 is vertically oriented. In some embodiments, H2 is at least about two times D6. In other embodiments, H2 can have another suitable value relative to D6.
Referring to
Downstream from the housing 102, the abrasive-delivery apparatus 100 can include an outlet conduit 138 extending vertically from the lower end portion 102b of the housing 102 to an abrasive-delivery conduit 140 extending between the abrasive-delivery apparatus 100 and a cutting head (not shown). The outlet conduit 138, for example, can be vertically oriented and can include an upper portion 138a at the lower end portion 102b of the housing 102 to a lower portion at abrasive-delivery conduit 140 when the abrasive-delivery apparatus 100 is vertically oriented. In some embodiments, the abrasive-delivery conduit 140 is slanted downward from the outlet conduit 138 toward the cutting head, such as to facilitate flow of particulate abrasive material by gravity. The abrasive-delivery apparatus 100 can further include a shutoff valve 142 operably connected to the outlet conduit 138 between the upper and lower portions 138a, 138b of the outlet conduit 138. The shutoff valve 142 can be configured to start or stop the flow of particulate abrasive material into the abrasive-delivery conduit 140 as needed (e.g., in concert with operation of the cutting head). In some embodiments, the shutoff valve 142 is pneumatic and operably connected to a pneumatic source 144. In other embodiments, the shutoff valve 142 can be electric, manual, or be configured to operate in accordance with another suitable modality.
In some embodiments, the metering element 146 is detachably connectable to the second funnel segment 108 and/or to the outlet conduit 138. For example, the metering element 146 and the second funnel segment 108 can include first complementary threads 154 at the second outlet 120, and the metering element 146 and the outlet conduit 138 can include second complementary threads 156 at the upper portion 138a of the outlet conduit 138. The diameter of the metering element 146 can be stepped down to form a lip 158 between the first and second complementary threads 154, 156 that is configured to abut an edge of the second outlet 120 when the first complementary threads 154 are fully engaged. The metering element 146 can be detached from the second funnel segment 108, for example, to allow substitution of a separate metering element (not shown) having a different D8 value. For example, the metering element 146 can be one of a set of metering elements (not shown) having different D8 values, such that different members of the set cause different flow rates of particulate abrasive material by gravity. In other embodiments, the metering element 146 can be fixedly connected to the second funnel segment 108. Furthermore, when detachable, the metering element 146 can be configured to detachably connect to the second funnel segment 108 and/or to the outlet conduit 138 by another suitable type of detachable coupling.
One or more aspects of the geometry of the metering elements 146, 400 can enhance the consistency and/or reliability of flowing particulate abrasive material in response to gravity. For example, the ratio of D4 to D8, the ratio of D4 to D10, the interior angle of the third interior regions 152, 406 (e.g., at the entry portions 152a, 406a and/or at the intervening portion 406c), and/or one or more other geometrical or other features of the metering elements 146, 400 can be selected to affect the flow characteristics of fine and/or coarse particulate abrasive materials. These geometrical or other features of the metering elements 146, 400 may affect fine and coarse particulate abrasive materials in a similar manner or differently. For example, in at least some cases, with respect to both fine and coarse particulate abrasive materials, it can be advantageous for the ratio of D4 to D8 and the ratio of D4 to D10 to be about 3:1 or greater (e.g., from about 3:1 to about 20:1), about 4:1 or greater (e.g., from about 4:1 to about 20:1), or greater than another suitable threshold value. By way of theory, and not to limit the scope of the present technology, this may reduce or prevent voids from developing within the third interior regions 152, 406, which may detrimentally affect the stability of flow of particulate abrasive materials (e.g., fine and/or coated particulate abrasive materials) through the third interior regions 152, 406. In some cases, the intervening portion 406c of the third interior region 406 may be better suited for enhancing the flow characteristics of coarse particulate abrasive materials than for enhancing the flow characteristics of fine particulate abrasive materials. Furthermore, in these and other cases, the intervening portion 406c of the third interior region 406 may be better suited for enhancing the flow characteristics of uncoated particulate abrasive materials than for enhancing the flow characteristics of coated particulate abrasive materials. In other cases, the intervening portion 406c of the third interior region 406 may have other relative compatibilities.
The ventilation tube 502 can be configured to vent entrained gas in particulate abrasive material in the vicinity of the third inlet 148. This entrained gas may detrimentally affect the stability of flow of particulate abrasive materials (e.g., fine and/or coated particulate abrasive materials) into and/or through the metering element 146. In some embodiments, the ventilation tube 502 includes a first opening (not shown) at the first end 502a and a second opening 504 outside of the first and second interior regions 122, 124 (e.g., within the filter 135). In other embodiments, the first opening and/or the second opening 504 can have other suitable positions. For example, the second opening 504 can be at the second end 502b. In addition to or instead of conveying entrained gas from particulate abrasive material in the vicinity of the third inlet 148, the ventilation tube 502 can be electrically conductive and configured to collect static electricity generated by funneling particulate abrasive material through the first and second funnel segments 106, 108. Thus, the ventilation tube 502 can supplement or replace the functionality of the static electricity collector 136 shown in
The ventilation tube 502 can be configured to rotate or otherwise move relative to the first and second funnel segments 106, 108, such as to agitate particulate abrasive material within the first and/or second interior regions 122, 124. For example, abrasive-delivery apparatus 500 can include a motor 505 operably connected to the ventilation tube 502 and configured to rotate the ventilation tube 502 about its longitudinal axis. The motor 505 can be configured to draw energy from an electrical supply 506. In some embodiments, the ventilation tube 502 includes one or more lateral projections 508 (e.g., fins) configured to stir or otherwise enhance agitation of particulate abrasive material within the first and/or second interior regions 122, 124. In other embodiments, the lateral projections 508 can be absent. Furthermore, instead of or in addition to the lateral projections 508, the abrasive-delivery apparatus 500 can include a first vibratory agitator 510 operably coupled to the first funnel segment 106 (e.g., at the outer surface 106a) and/or a second vibratory agitator 512 operably coupled to the second funnel segment 108 (e.g., at the outer surface 108a). In some embodiments, the first and second vibratory agitators 510, 512 can be pneumatic and operably connected to the pneumatic source 144. In other embodiments, the first and second vibratory agitators 510, 512 can be electric or be configured to operate in accordance with another suitable modality.
The method 700 can also include other suitable operations. As an example, the method 700 can include filtering the particulate abrasive material upstream from the first funnel segment 106. As another example, the method 700 can include collecting static electricity at the interior surface 106b of the first funnel segment 106 and/or at the interior surface 108b of the second funnel segment 108. The collected static electricity, for example, can be generated by funneling the particulate abrasive material through the first and second funnel segments 106, 108. As another example, the method 700 can include mechanically agitating the first funnel segment 106 while funneling the particulate abrasive material through the first funnel segment 106 and/or mechanically agitating the second funnel segment 108 while funneling the particulate abrasive material through the second funnel segment 108. As another example, the method 700 can include at least partially equilibrating a pressure differential between gas mixed with the particulate abrasive material within the second funnel segment 108 and atmospheric pressure. This can include, for example, venting the gas via the ventilation tube 502. As another example, the method 700 can include stirring the particulate abrasive material within the first funnel segment 106 while funneling the particulate abrasive material through the first funnel segment 106 and/or stirring the particulate abrasive material within the second funnel segment 108 while funneling the particulate abrasive material through the second funnel segment 108, such as by rotating the ventilation tube 502 about its longitudinal axis.
This disclosure is not intended to be exhaustive or to limit the present technology to the precise forms disclosed herein. Although specific embodiments are disclosed herein for illustrative purposes, various equivalent modifications are possible without deviating from the present technology, as those of ordinary skill in the relevant art will recognize. In some cases, well-known structures and functions have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments of the present technology. Although steps of methods may be presented herein in a particular order, in alternative embodiments, the steps may have another suitable order. Similarly, certain aspects of the present technology disclosed in the context of particular embodiments can be combined or eliminated in other embodiments. Furthermore, while advantages associated with certain embodiments may have been disclosed in the context of those embodiments, other embodiments can also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages or other advantages disclosed herein to fall within the scope of the present technology. Accordingly, this disclosure and associated technology can encompass other embodiments not expressly shown or described herein.
Certain aspects of the present technology may take the form of computer-executable instructions, including routines executed by a controller or other data processor. In some embodiments, a controller or other data processor is specifically programmed, configured, or constructed to perform one or more of these computer-executable instructions. Furthermore, some aspects of the present technology may take the form of data (e.g., non-transitory data) stored or distributed on computer-readable media, including magnetic or optically readable or removable computer discs as well as media distributed electronically over networks. Accordingly, data structures and transmissions of data particular to aspects of the present technology are encompassed within the scope of the present technology. The present technology also encompasses methods of both programming computer-readable media to perform particular steps and executing the steps.
The methods disclosed herein include and encompass, in addition to methods of making and using the disclosed materials, apparatuses, and systems, methods of instructing others to make and use the disclosed materials, apparatuses, and systems. For example, a method in accordance with a particular embodiment includes funneling particulate abrasive material through a first funnel segment, funneling the particulate abrasive material through a second funnel segment downstream from the first funnel segment, conveying the particulate abrasive material through an abrasive-delivery conduit from the second funnel segment to a cutting head, and incorporating the particulate abrasive material into a fluid jet within the cutting head. A method in accordance with another embodiment includes instructing such a method.
Throughout this disclosure, the singular terms “a,” “an,” and “the” include plural referents unless the context clearly indicates otherwise. Similarly, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. Additionally, the terms “comprising” and the like are used throughout this disclosure to mean including at least the recited feature(s) such that any greater number of the same feature(s) and/or one or more additional types of features are not precluded. Directional terms, such as “upper,” “lower,” “front,” “back,” “vertical,” and “horizontal,” may be used herein to express and clarify the relationship between various elements. It should be understood that such terms do not denote absolute orientation. Reference herein to “one embodiment,” “an embodiment,” or similar formulations means that a particular feature, structure, operation, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present technology. Thus, the appearances of such phrases or formulations herein are not necessarily all referring to the same embodiment. Furthermore, various particular features, structures, operations, or characteristics may be combined in any suitable manner in one or more embodiments.
This application claims the benefit of U.S. Provisional Application No. 61/801,571, filed Mar. 15, 2013, which is incorporated herein by reference in its entirety.
This invention was made in part using funds provided by the National Science Foundation Grant Nos. 0944239 and 1058278. The United States Government may have certain rights in this invention.
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