An abrasivejet cutting head system

Abstract

Disclosed is an abrasivejet cutting head system (apparatus and method) wherein the abrasive is introduced into the liquid jet stream at two or more locations and / or is dispersed before encountering the liquid jet stream, resulting in a more efficient cutting head system with a longer life.

Description

[0001] AN ABRASIVEJET CUTTING HEAD SYSTEM

[0002] CROSS REFERENCE TO RELATED APPLICATION

[0003] This application does not claim priority from any other application.

[0004] TECHNICAL FIELD

[0005] This invention relates to an abrasivejet cutting head system (apparatus and method) for use with a high velocity abrasive liquid jet cutting device.

[0006] BACKGROUND OF THE INVENTION

[0007] High velocity liquid jets laden with abrasives have been used to accurately cut a variety of materials for many years. A high velocity liquid jet is formed by compressing liquid (typically water) through an orifice having a very small diameter, and then an abrasive is entrained into the liquid. Due to the high pressure, the need to maintain a true edge and the dissipation of heat, certain dense materials are utilized to define the waterjet orifice, material such as a hard jewel such as sapphire, ruby or diamond. Abrasivejet machining (“AJM”) is also known as abrasive micro-blasting, pencil blasting and micro-abrasive blasting, all utilized in various abrasive cutting machining processes.

[0008] The enhancement of the cutting power achieved through the entrainment of abrasives into the liquid jet can be effectively used to cut a wide variety of exceptionally hard materials such as armor plate, cast-iron, steel, ceramics and bullet-proof glass.

[0009] As will be appreciated by those of ordinary skill in the art, the use of abrasive materials in a high-pressure liquid jet not only creates a great cutting tool, but also creates great abrasive wear on the tool and abrasivejet nozzle itself. This results in short tool or cutting head life and has caused those of ordinary skill in the art to seek ways to more efficiently and effectively introduce the abrasive materials into the liquid jet for both cutting effectiveness and increased wear characteristics for the cutting head.

[0010] It is therefore an object of embodiments of this invention to provide such an abrasive cutting head system that more efficiently and effectively introduces the abrasives into the liquid stream and thereby reduces the wear on the tool itself, which increases the nozzle life and the economic efficiency of embodiments of this invention.

[0011] Embodiments of this invention provide a system which, instead of following the prior art and introducing the abrasives to the liquid jet at one location, this invention discloses a system (apparatus and method) wherein the abrasive is introduced into the liquid jet stream at two or more locations and / or is dispersed in the liquid jet stream. These embodiments of the invention have the advantage of providing a longer tool life by as much as twenty-five percent and higher, coupled with increased cutting speeds and reduced power requirements.

[0012] Other objects, features, and advantages of this invention will appear from the specification, claims, and accompanying drawings which form a part hereof. In carrying out the objects of this invention, it is to be understood that its essential features are susceptible to change in design and structural arrangement, with only one practical and preferred embodiment being illustrated in the accompanying drawings, as required.

[0013] BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Preferred embodiments of the invention are described below with reference to the following accompanying drawings.

[0015] Figure 1 is a front elevation section view of one embodiment of this invention, illustrating an abrasivejet head cutting system;

[0016] Figure 2 is a front elevation partial section view of an embodiment of this invention;

[0017] Figure 3 is a front elevation partial section view of an embodiment of this invention;

[0018] Figure 4 is a front elevation partial section view of an embodiment of this invention; and

[0019] Figure 5 is a front elevation cross-sectional view of an embodiment of the DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Many of the fastening, connection, manufacturing and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art or science; therefore, they will not be discussed in significant detail. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application or embodiment of any element may already be widely known or used in the art or by persons skilled in the art or science; therefore, each will not be discussed in significant detail.

[0021] The terms “a”, “an”, and “the” as used in the claims herein are used in conformance with long-standing claim drafting practice and not in a limiting way. Unless specifically set forth herein, the terms “a”, “an”, and “the” are not limited to one of such elements, but instead mean “at least one”.

[0022] In most applications a jet of water or other suitable liquid is formed by first pressurizing liquid (typically water) to 3000 to 150,000 psig and then presenting said liquid to a sharp edge orifice through a conduit or passageway configured to facilitate the movement of the liquid. The orifice diameters currently range from approximately 0.003 inches to 0.060 inches. The resulting laminar flowing liquid jet moving from the conduit through the sharp edge orifice will transfer the energy stored as pressure into a small amount of heat and kinetic energy in the stream velocity-mass. Such streams can attain speeds in excess of three times the speed of sound, or over 3000 fpm (feet per minute).

[0023] Since the abrasive materials are subjected to the high-speed stream of liquid, which causes the abrasives to travel at an extremely high speed, this makes each grain of abrasive a tool capable of cutting most any material. Garnet is the most widely applied abrasive material used for application in an abrasivejet.

[0024] The high-speed liquid jet passes through the mixing chamber, which is also a venturi. The venturi creates a vacuum which pulls the abrasive into the region of the jet stream, which is sometimes referred to as the entrainment of the abrasive into the jet stream of liquid. Typically, the venturi effect will cause a vacuum of 20 to 40 inches of mercury to be applied to the abrasive feed tube.

[0025] Most of the abrasivejet cutting heads introduce the abrasive to the liquid jet stream in a region oftentimes referred to as the mixing chamber. The abrasive enters the mixing chamber lateral to the jet stream and moves through the mixing chamber quickly as it attains speeds to produce the cutting action. In traveling through the mixing chamber and then with the liquid jet into the abrasivejet nozzle. The stream of abrasive tends to maintain a singular stream flowing down with the liquid jet but in a helical path as it travels through the abrasivejet nozzle.

[0026] The liquid jet (which is laden with abrasive) will enter the pathway through the abrasivejet nozzle which is, in operation, positioned to impinge upon some workpiece or material that is desired to be cut. The passage of the abrasive and liquid at the high speeds and pressures causes extreme wear on the components such as the abrasive supply conduit, the mixing chamber, the orifice and the abrasivejet nozzle. This is when it becomes apparent that these components have incurred excessive wear and must be changed out or replaced (the wear impedes the effectiveness of the abrasivejet stream in cutting the desired workpiece or material).

[0027] Embodiments of this invention may utilize a typical abrasivejet cutting head configuration which utilizes high-pressure water entering through an orifice to form a longitudinal coherent liquid stream to which an abrasive is introduced within the area referred to as the mixing chamber.

[0028] In some embodiments of this invention, the cutting head assembly includes novel configurations and methods to introduce the abrasive to the jet stream in the mixing chamber area. In some embodiments of this invention, eliminating the abrasive single stream and dispersing the abrasive prior to entering the entrainment area in a manner that produces a plurality of abrasive streams reduces the necessary abrasive rates and decreases wear on the various components of the cutting head, including without limitation, wear on the nozzle, mixing chamber, conduits or apertures, etc. It will be appreciated by those of ordinary skill in the art that the novel configurations and methods in embodiments of this invention will also increase cutting speeds. Embodiments of this invention address a known critical element to the effectiveness and efficiency of abrasivejet cutting heads, namely importance of achieving the most efficient introduction of the abrasive material into and with the waterjet stream. This is demonstrated in direct-jets wherein the abrasive is suspended in the liquid before the jet is formed. Cutting speeds and quality of cut area achieved with 20% of the pressure that abrasivejets utilize.

[0029] Embodiments of this invention may include an abrasivejet cutting head assembly which has a body having a longitudinally extending throughpassageway extending about a longitudinal axis between the upstream and downstream and regions of the cutting head. The existence of a sharp edge orifice at the entry produces the coherent stream which is centered axially to pass through the length of the cutting head assembly. Within the area above the entrainment area the waterjet stream is protected by the jet guard by passing through the jet guard passage. Upon exiting the protected region, the jet stream is introduced to the abrasive material entering the entrainment area, referred in current abrasivejet cutting heads as the mixing chamber area in a dispersed arrangement about the axially positioned liquid jet. The mixing chamber area is also a venturi to assist the flow of abrasive to be introduced to the stream of liquid or water.

[0030] By introducing the abrasive to the jet stream in a dispersed manner, the cutting efficiencies are enhanced, in some cases as much or more than 20% to 25%.

[0031] Figure 1 is a front elevation section view of one embodiment of this invention, illustrating an abrasivejet head cutting system 100, with cutting head body 140 (which holds the upper portion 1 18, waterjet guard 108, orifice mount 101 , and lower portion 117, in position or in registration). The entrainment region may be in the upper portion and / or the lower portion (nozzle portion).

[0032] The lower portion 117 may also be referred to as the abrasivejet nozzle which consists of the longitudinal passage 103, the nozzle body 102, and the discharge port 104, at the lower or exit end. Figure 1 further illustrates orifice 105, jet longitudinal passage 106, abrasive inlet area 107 and the entrainment area 110 (which extends conically into the nozzle portion as shown). The jet longitudinal passage 106 serves in part to protect the water jet as it passes by the entry point of the abrasive in order to maintain the integrity of the jet streams. In embodiments of the invention, the waterjet stream flows into the longitudinal passage of the abrasivejet nozzle mostly in line until exiting the working end of the abrasivejet nozzle.

[0033] The entrainment area 110 is where the abrasive is entrained within the liquid before being carried through the longitudinal passage 103 in the abrasivejet nozzle 102. Figure 1 also schematically shows a source of high- pressure water 133 in operable communication with orifice 105. It is noted that the individual parts may be combined as best suited for manufacture, operation and / or service.

[0034] Figure 2 is a front elevation partial section view of an embodiment of this invention, illustrating abrasivejet head cutting system 100, with cutting head body 140 (shown in Figure 1), abrasive jet nozzle 102, abrasive passageway 124, and discharge port 104. Figure 2 further illustrates orifice 105, jet longitudinal passage 106, abrasive inlet area 107, jet guard 108, abrasive dispersion elements 112 (abrasive dispersion geometric shaped elements, ridges, threads or protrusions), and the entrainment area 110. Figure 2 further illustrates one example of an embodiment of this invention which utilizes disbursement bodies which scatter the stream of abrasive causing it to enter the entrainment area distributed as evenly as possible about the annulus which is the entrance to the entrainment area 110. The abrasive then becomes entrained with the liquid jet from all lateral directions as evenly as possible.

[0035] Figure 3 is a front elevation partial section view of an embodiment of this invention, illustrating abrasivejet head cutting system 100, with cutting head body 140 (shown in Figure 1), abrasive jet nozzle 102, and port of abrasivejet discharge 104. Figure 3 further illustrates orifice 105, jet longitudinal passage 106, abrasive inlet area 107, jet guard 108, entrainment area 110, first abrasive dispersion aperture 115, second abrasive dispersion aperture 116, and abrasive inlet 113 (which feeds / supplies abrasive material to both the first abrasive dispersion aperture 115 and the second abrasive dispersion aperture 116). More such abrasive channels, passages or apertures may be added as necessary to attain the desired level of abrasive scatter or dispersion. Figure 3 illustrates dispersion of the abrasive stream utilizing a plurality of passages or apertures (115 & 116) which carry the abrasive from the abrasive inlet 113 to the entrainment area 110. Embodiments of this invention are not limited to the two passages, channels or apertures 115 & 116 but may also include more such passages, apertures or channels as deemed necessary.

[0036] Figure 4 is a front elevation partial section view and partial schematic of an embodiment of this invention, illustrating abrasivejet head cutting system 100, with cutting head body 140 (shown in Figure 1), abrasive jet nozzle 102, and abrasivejet discharge port 104. Figure 4 further illustrates orifice 105, jet longitudinal passage 106, abrasive inlet area 107, waterjet guard 108, entrainment area 110, dispersion body 119, abrasive channel or abrasive passageway 122, geometric shapes or protrusions 123 in abrasive passageway 122 to facilitate dispersion of the abrasive, and excitement transducer 120 (which vibrates dispersion body 119).

[0037] Figure 4 illustrates a dispersion area which uses geometric shapes on a flexible material to hold the abrasives as a transducer 120 imparts high frequency motion to the dispersion area which excites the abrasives such that the abrasives enter the entrainment area 110 at a more dispersed state.

[0038] Figure 5 is a front elevation cross-sectional view of another embodiment of the invention, illustrating orifice 105, abrasive jet nozzle 102, waterjet guard 108, orifice mount 101 , entrainment area 110, dispersion and entrainment area containment shell 134, abrasive inlet 139, abrasive passageway 138, longitudinal passageway 103 within abrasive jet nozzle which includes a mixture of abrasive and water / liquid. In this embodiment, protrusions 131 or dispersion element 131 within the abrasive passageway 138 interact with the abrasives moving therethrough to create a desired pattern of movement for the abrasives.

[0039] It will be appreciated by those of ordinary skill in the art that materials of all parts of the cutting head can be varied to obtain desired results in operation, useful life and serviceability.

[0040] As will be appreciated by those of reasonable skill in the art, there are numerous embodiments to this invention, and variations of elements and components which may be used, all within the scope of this invention. In one embodiment for example, an abrasivejet cutting head may be provided, which comprises: a body having a first internal longitudinally extending through passageway between upstream and downstream end regions about the longitudinal axis; a waterjet forming orifice member within the passageway for producing a generally axially aligned waterjet when the passageway upstream of the orifice is coupled with a source of high-pressure fluid; abrasive feed means for permitting entry of abrasive material into the passageway through an inlet conduit and said abrasive being entrained with the waterjet stream within the entrainment region longitudinally downstream from the entry of abrasive material; a means for preventing abrasive contact with the wateijet stream or disturbing its longitudinal direction prior to reaching the entrainment region; and a means for axially and longitudinally securing an abrasivejet nozzle in a lower position of the longitudinal passageway to direct the abrasive wateijet at the work piece to be processed.

[0041] In addition to the embodiment disclosed in the preceding paragraph, the invention may further include: means for imparting dispersion of the abrasive material about the passageway prior to entrainment with the waterjet stream and upstream of the entrainment area; a cutting head wherein said inlet axis is located at any lateral position to the longitudinal center axis of said head and may enter at any angle from horizontal to vertical and be accessed by means of a permanent or replaceable fitting to which an abrasive carrying conduit can be affixed to supply abrasive materials to the cutting head; a cutting head which includes an abrasive dispersion area made of a generally tapered cone with dispersion members located about the conical surface; wherein the dispersion area uses multiple channels or passages to disperse the abrasive prior to entry into the entrainment area; wherein the dispersion area is produced using a material to which high frequency vibrations can be imparted thus exciting the abrasive entering the disbursement area causing the abrasive to disperse prior to entering the entrainment area; and / or wherein the induced vibrations within the disbursement area create a fluidized-bed of abrasive prior to entering the entrainment area.

[0042] A still further embodiment may provide an abrasivejet cutting head with means of protecting the waterjet from external forces or materials; or an abrasivejet cutting head with an entrainment area longitudinally after the area where the waterjet is protected from disturbance and prior to the abrasivejet nozzle. In yet another embodiment, an abrasivejet cutting head may be provided with the ability to secure a nozzle with an inside diameter ranging from 0.004 to 0.100 inch in lateral and longitudinal alignment with the waterjet formed by the orifice secured longitudinally prior to the nozzle. In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.

Claims

CLAIMSI / We Claim:

1. An abrasivejet cutting head comprising: a cutting head body with an upper portion and a lower portion with an internal longitudinally oriented passageway extending through the cutting head body, the passageway including an inlet region, an entrainment area, and a nozzle outlet region; a waterjet forming orifice member within the passageway for producing a generally axially aligned waterjet when the passageway upstream of the orifice is coupled with a source of high-pressure liquid; a water jet guard disposed within the cutting head body to shield the waterjet upstream, of the entrainment area; a source of abrasive disposed to provide abrasive to an abrasive passageway in the cutting head body, the abrasive passageway facilitating delivery of the abrasive to the entrainment area; the abrasive passageway including at least one dispersion geometric shaped element therein to radially disburse the abrasive entering the entrainment area; and the lower portion of the cutting head body configured to deliver the waterjet entrained with abrasive through the outlet.

2. The abrasivejet cutting head as described in claim 1, and further wherein the at least one dispersion geometric shaped element is a protrusion, thread or ridge.

3. An abrasivejet cutting head comprising: a cutting head body with an upper portion and a lower portion with an internal longitudinally oriented passageway extending through the cutting head body, the passageway including an inlet region, an entrainment area, and a nozzle outlet region; a waterjet forming orifice member within the passageway for producing a generally axially aligned waterjet when the passageway upstream of the orifice is coupled with a source of high-pressure liquid;a water jet guard disposed within the cutting head body to shield the waterjet upstream, of the entrainment area; a source of abrasive disposed to provide abrasive to an abrasive passageway in the cutting head body, the abrasive passageway facilitating delivery of the abrasive to the entrainment area; the abrasive passageway being comprised of two or more passageways for delivery of the abrasive to the entrainment area in a dispersed pattern; including at least one dispersion protrusion therein to radially disburse the abrasive entering the entrainment area; and the lower portion of the cutting head body configured to deliver the waterjet entrained with abrasive through the outlet.

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