Patent Grant
8006915
The present invention relates, in general, to high-pressure waterjets for cleaning and cutting and, in particular, to high-frequency modulated waterjets.
Continuous-flow high-pressure waterjets are well known in the art for cleaning and cutting applications. Depending on the particular application, the water pressure required to produce a high-pressure waterjet may be in the order of a few thousand pounds per square inch (psi) for fairly straightforward cleaning tasks to tens of thousands of pounds per square inch for cutting and removing hardened coatings.
Examples of continuous-flow, high-pressure waterjet systems for cutting and cleaning are disclosed in U.S. Pat. No. 4,787,178 (Morgan et al.), U.S. Pat. No. 4,966,059 (Landeck), U.S. Pat. No. 6,533,640 (Nopwaskey et al.), U.S. Pat. No. 5,584,016 (Varghese et al.), U.S. Pat. No. 5,778,713 (Butler et al.), U.S. Pat. No. 6,021,699 (Caspar), U.S. Pat. No. 6,126,524 (Shepherd) and U.S. Pat. No. 6,220,529 (Xu). Further examples are found in European Patent Applications EP 0 810 038 (Munoz) and EP 0 983 827 (Zumstein), as well as in U.S. Patent Application Publications US 2002/0109017 (Rogers et al.), US 2002/0124868 (Rice et al.), and US 2002/0173220 (Lewin et al.).
Continuous-flow waterjet technology, of which the foregoing are examples, suffers from certain drawbacks which render continuous-flow waterjet systems expensive and cumbersome. As persons skilled in the art have come to appreciate, continuous-flow waterjet equipment must be robustly designed to withstand the extremely high water pressures involved. Consequently, the nozzle, water lines and fittings are bulky, heavy and expensive. To deliver an ultra-high-pressure waterjet, an expensive ultra-high-pressure water pump is required, which further increases costs both in terms of the capital cost of such a pump and the energy costs associated with running such a pump.
In response to the shortcomings of continuous-flow waterjets, an ultrasonically pulsating nozzle was developed to deliver high-frequency modulated water in non-continuous, virtually discrete packets, or “slugs”. This ultrasonic nozzle is described and illustrated in detail in U.S. Pat. No. 5,154,347 (Vijay) which issued on Oct. 13, 1992. The ultrasonic nozzle disclosed in U.S. Pat. No. 5,154,347 transduced ultrasonic oscillations from an ultrasonic generator into ultra-high frequency mechanical vibrations capable of imparting thousands of pulses per second to the waterjet as it travels through the nozzle. The waterjet pulses impart a waterhammer pressure onto the surface to be cut or cleaned. Because of this rapid bombardment of mini-slugs of water, each imparting a waterhammer pressure on the target surface, the erosive capacity of the waterjet is tremendously enhanced. The ultrasonically pulsating nozzle which cuts or cleans is thus able to cut or clean much more efficiently than the prior-art continuous-flow waterjets.
Theoretically, the erosive pressure striking the target surface is the stagnation pressure, or 1/2.rho.v.sup.2 (where ρ represents the water density and v represents the impact velocity of the water as it impinges on the target surface). The pressure arising due to the waterhammer phenomenon, by contrast, is ρcv (where c represents the speed of sound in water, which is approximately 1524 m/s). Thus, the theoretical magnification of impact pressure achieved by pulsating the waterjet is 2 c/v. Even if air drag neglected and the impact velocity is assumed to approximate the fluid discharge velocity of 1500 feet per second (or approximately 465 m/s), the magnification of impact pressure is about 6 to 7. If the model takes into account air drag and the impact velocity is about 300 m/s, then the theoretical magnification would be tenfold.
In practice, due to frictional losses and other inefficiencies, the pulsating ultrasonic nozzle described in U.S. Pat. No. 5,154,347 imparts about 6 to 8 times more impact pressure onto the target surface for a given source pressure. Therefore, to achieve the same erosive capacity, the pulsating nozzle need only operate with a pressure source that is 6 to 8 times less powerful. Since the pulsating nozzle may be used with a much smaller and less expensive pump, it is more economical than continuous-flow waterjet nozzles. Further, since waterjet pressure in the nozzle, lines, and fittings is much less with an ultrasonic nozzle, the ultrasonic nozzle can be designed to be lighter, less cumbersome and more cost-effective.
Although the ultrasonic nozzle described in U.S. Pat. No. 5,154,347 represented a substantial breakthrough in waterjet cutting and cleaning technology, further refinements and improvements were found by the Applicant to be desirable. The first iteration of the ultrasonic nozzle, which is described in U.S. Pat. No. 5,154,347, proved to be sub-optimal because it was used in conjunction with pre-existing waterjet generators. A need therefore arose for a complete ultrasonic waterjet apparatus which takes full advantage of the ultrasonic nozzle.
It also proved desirable to modify the ultrasonic nozzle to make it more efficient from a fluid-dynamic perspective, to be able to clean and remove coatings more efficiently from large surfaces, and to be more ergonomic in the hands of the end-user.
Accordingly, in light of the foregoing deficiencies, it would be highly desirable to provide an improved ultrasonic waterjet apparatus.
A main object of the present invention is to overcome at least some of the deficiencies of the above-noted prior art.
This object is achieved by the elements defined in the appended independent claims. Optional features and alternative embodiments are defined in the subsidiary claims.
Thus, an aspect of the present invention provides an ultrasonic waterjet apparatus including a generator module which has an ultrasonic generator for generating and transmitting high-frequency electrical pulses; a control unit for controlling the ultrasonic generator; a high-pressure water inlet connected to a source of high-pressure water; and a high-pressure water outlet connected to the high-pressure water inlet. The ultrasonic waterjet apparatus further includes a high-pressure water hose connected to the high-pressure water outlet and a gun connected to the high-pressure water hose. The gun has an ultrasonic nozzle having a transducer for receiving the high-frequency electrical pulses from the ultrasonic generator, the transducer converting the electrical pulses into vibrations that pulsate a waterjet flowing through the nozzle, creating a waterjet of pulsed slugs of water, each slug of water capable of imparting a waterhammer pressure on a target surface.
Preferably, the transducer is piezoelectric or piezomagnetic and is shaped as a cylindrical or tubular core.
Preferably, the gun is hand-held and further includes a trigger for activating the ultrasonic generator whereby a continuous-flow waterjet is transformed into a pulsated waterjet. The gun also includes a dump valve trigger for opening a dump valve located in the generator module.
Preferably, the ultrasonic waterjet apparatus has a compressed air hose for cooling the transducer and an ultrasonic signal cable for relaying the electrical pulses from the ultrasonic generator to the transducer.
For cleaning or de-coating large surfaces, the ultrasonic waterjet apparatus includes a rotating nozzle head or a nozzle with multiple exit orifices. The rotating nozzle head is preferably self-rotated by the torque generated by a pair of outer jets or by angled orifices.
An advantage of the present invention is that the ultrasonic waterjet apparatus generates a much higher effective impact pressure than continuous-flow waterjets, thus augmenting the apparatus' capacity to clean, cut, deburr, de-coat and break. By pulsating the waterjet, a train of mini slugs of water impact the target surface, each slug imparting a waterhammer pressure. For a given pressure source, the waterhammer pressure is much higher than the stagnation pressure of a continuous-flow waterjet. Therefore, the ultrasonic waterjet apparatus can operate with a much lower source pressure in order to cut and deburr, to clean and remove coatings, and to break rocks and rock-like substances. The ultrasonic waterjet apparatus is thus more efficient, more robust, and less expensive to construct and utilize than conventional continuous-flow waterjet systems.
Another aspect of the present invention provides an ultrasonic nozzle for use in an ultrasonic waterjet apparatus. The ultrasonic nozzle includes a transducer for converting high-frequency electrical pulses into mechanical vibrations that pulsate a waterjet flowing through the nozzle, creating a waterjet of pulsed slugs of water, each slug of water capable of imparting a waterhammer pressure on a target surface. The nozzle has a rotating nozzle head or multiple exit orifices for cleaning or de-coating large surfaces.
Another aspect of the present invention provides an ultrasonic nozzle for use in an ultrasonic waterjet apparatus including a transducer for converting high-frequency electrical pulses into mechanical vibrations that pulsate a waterjet flowing through the nozzle, creating a waterjet of pulsed slugs of water, each slug of water capable of imparting a waterhammer pressure on a target surface, the transducer having a microtip with a seal for isolating the transducer from the waterjet, the seal being located at a nodal plane where the amplitude of standing waves set up along the microtip is zero.
Another aspect of the present invention provides related methods of cutting, cleaning, deburring, de-coating and breaking rock-like materials with an ultrasonically pulsed waterjet. The method includes the steps of forcing a high-pressure continuous-flow waterjet through a nozzle; generating high-frequency electrical pulses; transmitting the high-frequency electrical pulses to a transducer; transducing the high-frequency electrical pulses into mechanical vibrations; pulsating the high-pressure continuous flow waterjet to transform it into a pulsated waterjet of discrete water slugs, each water slug capable of imparting a waterhammer pressure on a target surface; and directing the pulsated waterjet onto a target material. Depending on the desired application, the ultrasonically pulsed waterjet can be used to cut, clean, de-burr, de-coat or break.
Where the application is cleaning or de-coating a large surface, the ultrasonic waterjet apparatus advantageously includes a nozzle with multiple exit orifices or with a rotating nozzle head.
Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
The hand-held gun 50 has a pulsing trigger 52 and a dump valve trigger 54. The hand-held gun also has an ultrasonic nozzle 60. The ultrasonic nozzle 60 has a transducer 62 which is either a piezoelectric transducer or a piezomagnetic transducer. The piezomagnetic transducer is made of a magnetostrictive material such as a Terfenol™ alloy.
As illustrated in
Still referring to
As shown in
As shown in
With reference to
The ultrasonic nozzle may be fitted onto a hand-held gun as shown in
The continuous-flow waterjet enters through a water inlet downstream of the transducer as shown in
Although the microtip may be shaped in a variety of manners (conical, exponential, etc.), the preferred profile of the microtip is that of a stepped cylinder, as shown in
As shown in
In a third embodiment, which is illustrated in
As shown in
For underwater operations, the piezomagnetic, transducer is used rather than the piezoelectric which cannot be immersed in water. The piezomagnetic transducer 62 can be packaged inside the nozzle 60 unlike the piezoelectric transducer. The piezomagnetic transducer uses a magnetostrictive material such as one of the commercially available alloys of Terfenol™. These Terfenol-based magnetostrictive transducers are compact and submergible in the nozzle 60 as shown in
For short-duration applications, which do not require rotating nozzle heads, the configuration shown in
For long period of operation, or for operating in a rotating configuration, this type of airflow cooling is not a viable solution. The configurations shown in
For rotating nozzle heads incorporating two or more orifices, the configurations illustrated in
The embodiment(s) of the invention described above is (are) intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.
The present application is a continuation of U.S. patent application Ser. No. 10/577,718, filed May 2, 2006 and published Mar. 22, 2007 as U.S. Patent Application Publication 2007/0063066, which is a national stage of PCT/CA03/01683 filed Nov. 3, 2003.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2835158 | Bartlow | May 1958 | A |
| 3255626 | Van Der Veer | Jun 1966 | A |
| 3373752 | Inoue | Mar 1968 | A |
| 3946599 | Patt | Mar 1976 | A |
| 4185706 | Baker, III et al. | Jan 1980 | A |
| 4326553 | Hall | Apr 1982 | A |
| 4681264 | Johnson, Jr. | Jul 1987 | A |
| 4716849 | Conn et al. | Jan 1988 | A |
| 4738139 | Blessing et al. | Apr 1988 | A |
| 4787178 | Morgan et al. | Nov 1988 | A |
| 4821961 | Shook | Apr 1989 | A |
| 4966059 | Landeck | Oct 1990 | A |
| 5020724 | Kiyono et al. | Jun 1991 | A |
| 5154347 | Vijay | Oct 1992 | A |
| 5217163 | Henshaw | Jun 1993 | A |
| 5584016 | Varghese et al. | Dec 1996 | A |
| 5725680 | Mathieus | Mar 1998 | A |
| 5778713 | Butler et al. | Jul 1998 | A |
| 6021099 | Aoki et al. | Feb 2000 | A |
| 6126524 | Shepherd | Oct 2000 | A |
| 6220529 | Xu | Apr 2001 | B1 |
| 6424078 | Heinz | Jul 2002 | B1 |
| 6533640 | Nopwaskey et al. | Mar 2003 | B1 |
| 7117741 | Klein et al. | Oct 2006 | B2 |
| 7549429 | Nunomura et al. | Jun 2009 | B2 |
| 7594614 | Vijay et al. | Sep 2009 | B2 |
| 20020109017 | Rogers et al. | Aug 2002 | A1 |
| 20020124868 | Rice et al. | Sep 2002 | A1 |
| 20020173220 | Lewin et al. | Nov 2002 | A1 |
| 20080135638 | Foldyna et al. | Jun 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| 0 810 038 | Dec 1997 | EP |
| 0 829 311 | Mar 1998 | EP |
| 0 983 827 | Mar 2000 | EP |
| 1 016 469 | Jul 2000 | EP |
| 955 405 | Apr 1964 | GB |
| 2 029 270 | Mar 1980 | GB |
| WO 9213679 | Aug 1992 | WO |
| WO 2005042177 | May 2005 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20090308948 A1 | Dec 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10577718 | US | |
| Child | 12546209 | US |
