SELF-ALIGNING, SPRING-DISK WATERJET ASSEMBLY

Abstract

A spring disk with a concentric through bore and a concentric counter bore of specific depth in used to hold an orifice against a lapped surface of a nozzle cap in a waterjet assembly. Dimensions are chosen to provide adequate restraint without the need to force the orifice onto the spring disk. When orifice, spring disk and the retaining cap are assembled and the cap is tightened on the inlet nozzle, the spring disk is forced to the cap surface and the orifice becomes securely held and centrally aligned within the assembly.

Description

BACKGROUND OF INVENTION

[0002] The invention relates generally to high-pressure fluid jet nozzles and more particularly to an orifice jet nozzle assembly for waterjet cutting systems and the like that use high-pressure fluids to form a high-energy stream for solid material cutting and similar processes. The proper alignment of the orifice that forms the water stream is essential to proper function and accurate cutting. The orifice must also be replaced at frequent intervals. The process of orifice installation and alignment takes time and cannot be done by machine operators under field conditions. Furthermore, all current waterjet systems allow for only a single orifice per nozzle. The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide a means that allows for easy installation and alignment of orifices by operating waterjet system personnel, and allows for multiple orifices from a single nozzle that allow multiple waterjet streams. Accordingly, a suitable method is provided that allows easy replacement and alignment of orifices by field personnel, and allows multiple orifices in a single nozzle. The assembly can also be used to maintain consistent alignment with a down stream mixing tube, such as used in abrasive waterjet cutting.

SUMMARY OF INVENTION

[0003] The invention uses a spring disk to retain and align an orifice(s) on a smooth flat surface. The spring disk has a large outside diameter, one or more through-holes in area of center of its surface, and, concentric with the through-holes, shallow recesses (or counterbores). The wells are slightly larger in diameter than the particular orifice to be mounted and slightly shallower than the thickness of the orifice. The orifice(s) is (are) placed into the recesses (counterbores). When installing an orifice, a small amount of a viscous liquid, such as water with soap, will prevent the orifice(s) from falling out of the recess(es). The nozzle cap is made with a recess (counterbore) that has a diameter that is slightly larger than the spring disk and has through-holes that are concentric with the orifice hole. The recessed surface of the cap is lapped so that it is very flat and smooth. The diameter of the spring disk is larger than the inner diameter of the inlet tube. When the cap is mounted on the inlet tube and tightened, the outer diameter of the spring disk is forced to flex to the cap surface while the center portion is restrained by the orifice that is resting on the same cap surface. This imposes a force (a preload) on the orifice(s) which acts on the lapped surface of the cap. The force on the orifice(s) is a function of the diameter, thickness and displacement of the outer portion of the spring disk. This force is not sufficient to prevent fluid from leaking around the orifice. The principle that works to provide total sealing is a self-actuating concept that uses the difference in area between the top of the orifice and the bottom that is resting on the lapped surface. The hole through the cap is larger than the diameter of the bore through the orifice. The inlet area of the orifice (exposed to high pressure fluid) is larger than the area of the orifice resting on the lapped surface. The resulting effect is that the stress acting on the orifice at the lapped surface is much greater than the stress at the inlet area of the orifice. As a result, when the lapped area is smooth, fluid cannot leak past the orifice. In addition, the spring disk may be bored and counterbored to allow placement of several orifices at specified distances from each other to permit multiple waterjets for simultaneous cutting.

BRIEF DESCRIPTION OF DRAWINGS

[0004] FIG. 1 is a cross section of prior art nozzle assembly.

[0005] FIG. 2 is a cross section of prior art support system for orifice.

[0006] FIG. 3 is a cross section of improved prior art method for aligning and confining orifice.

[0007] FIG. 4 is a cross section of nozzle assembly for use with the present invention.

[0008] FIG. 5 is a cross section of nozzle cap, inlet tube, spring disk and orifice for use with the present invention.

[0009] FIG. 6 is a cross section of an alternate configuration employing the spring disk.

[0010] FIG. 7 is a cross section of orifice and nozzle cap for use with the present invention showing principle of difference in high pressure area that prevents leakage around the orifice.

[0011] FIG. 8 is a cross section of a typical abrasive Waterjet nozzle using the spring disk.

DETAILED DESCRIPTION

[0012] FIG. 1 shows a mounting assembly capable of accepting an orifice. As shown in FIG. 1, a piece of high pressure conveyance tubing, designated by the reference numeral 1, is provided with a threaded end 2, onto which a nozzle cap 3 is screwed to secure and hold in place an orifice system 4 between lands 5 of the nozzle cap and an alignment and seal taper 7 of the tube 1. For cutting solid material, cutting fluid, usually water under high pressures usually above 20,000 psi, is supplied to the interior 8 of the inlet tube 1 and escapes as a focused stream through orifice bore 6. This concentrated fluid jet performs the cutting process on solid materials.

[0013] FIG. 2 shows a nozzle according to a prior art which might be installed in the nozzle fixture formed by nozzle tube 1 and nozzle cap 3, as shown in FIG. 1. The nozzle is formed of a body portion 9 having an internal bore 15 provided through the center of the body. A complementary seal taper 11 cooperates with the taper surface 4 of tube 1 to align and seal the orifice body 9 in the assembly. A typical orifice 10 is shown mounted in counterbore 12 in the orifice body a polymer seal 13 material is pressed in to the annulus between the orifice 10 outside diameter and the counterbore wall. This retains the orifice. Although generally acceptable, this embodiment of the prior art fails to provide a positive means of securing the nozzle 10 within the orifice body 9. Due to the high operating pressures and sometimes rapid fluctuations in pressure, the orifices frequently become dislodged. In addition, erosion around the orifice has occurred at times thus permitting the orifice to move laterally out of focus or become more easily dislodged from its mounting. In applications using extreme high or low temperature fluids, the polymer seal 13 fails, resulting in orifice failure.

[0014] FIG. 3 shows a more recent prior art in which a mounting body 14 is provided with a central through bore 15, a mounting flange 16 for mating with lands 5 of nozzle cap 3, and a cylindrical head 17 which is further provided with a counterbore 18 which receives a orifice 10 having an orifice bore 19 which aligns axially along the mounting through bore 15. Also shown is retaining hat 20 with a conical surface 21 and a cylindrical bore 22, which cooperates with cylindrical head 14 by means of an interference fit to secure the conical hat 20 on the head 17. The conical hat 20 is further provided with an internal flange 23 which presses on and secures the orifice 10 in the bore 18 of the head 14. This prior art secures the orifice in place and provides alignment for the jet stream. While the prior art provides for a positive system for securing the orifice, it is a complex and expensive design that requires special tools and does not allow for replacement of the orifice by field personnel. According to the present invention, the orifice supporting system is much simpler, is easily aligned, and allows the orifice to be replaced by operating field personnel; no special tools or training are required. This results in much lower orifice replacement costs and reduces the waterjet cutting system down time.

[0015] FIGS. 4, 5, 6, 7, and 8 refer to the present invention. FIG. 4 shows a waterjet assembly capable of accepting a orifice. A piece of high pressure tubing, designated by the reference numeral 1, is provided with a threaded end 2, onto which a nozzle cap 25 is screwed to secure a spring disk 24 between lapped surface 27 of the nozzle cap and the end of the nozzle tube 28. The spring disk is designed to confine and concentrically align orifice(s) 26 with the throughbore of the spring disk and the nozzle cap.

[0016] FIG. 5 shows spring disk 24 with a thickness slightly smaller than the orifice with a recess (counterbore) 29 that receives orifice 26 having an orifice bore 30. Recess (counterbore) 30 has a depth that is smaller than the height of the orifice and aligns axially with bore 31 of the nozzle cap. The orifice is restrained by a flange 32 of the spring disk. The nozzle cap 25 is made with a recess (counterbore) 33 that has a height that is smaller than the spring disk, a diameter that is slightly larger than the spring disk, and throughhole(s) 31 that is (are) concentric with the orifice hole 30. The recessed surface 27 of the nozzle cap is lapped so that the surface is flat and smooth. The diameter of the spring disk 24 is slightly larger than the diameter of the inlet tube 1. When the nozzle cap 25 is mounted on the inlet tube 1 and tightened, the outer diameter of the spring disk 24 is forced to flex to the nozzle cap surface 27 while the center portion is restrained by the orifice 24 held in place by flange 32 and rests on the lapped surface 27 of the nozzle cap 25. This secures and aligns the orifice and prevents the possibility of movement or escape of orifice 26. The center portion of the spring disk 24 may contain thru bore(s) 34. The thru bore(s) prevent pressure imbalances from occurring between the top and bottom of the spring disk 24 that could cause over flexing and failure of the spring disk 24. The thru bore(s) are located in the annulus between the bore of the inlet tube 1 and the recess 29.

[0017] FIG. 6 shows an alternate configuration of the assembly shown in FIG. 5 where the recess 29 is located in the nozzle cap 25.

Claims

1. A waterjet assembly consisting of: a spring disk having a through bore; concentric with the outside diameter; said spring disk being provided with a concentric counter bore of accurately defined depth and diameter; an orifice having a height slightly greater than the depth of the accurately defined counter bore depth, inserted into said counter bore; a nozzle cap with a concentric through bore, larger than orifice inner diameter but smaller than orifice outer diameter; and said nozzle cap attached to fluid conveyance tube, clamping the spring disk and orifice.

2. A waterjet orifice assembly according to claim 1 wherein: said nozzle cap is further provided with a lapped surface on which the orifice is to rest; said nozzle cap provided with concentric counter bore with diameter that allows fit of the spring disk, with a depth that is smaller than the height of the spring disk; and said nozzle has cap through bore aligned with orifice.

3. A waterjet orifice assembly according to claim 1 wherein: said spring disk has sufficiently thin surface and sufficient flexure to prevent crushing the orifice when the cap is tightened to secure the orifice in place.

4. A waterjet orifice assembly according to claim 1 wherein: the said spring disk provides for a system in which the orifice is subjected to uniform stress on the inlet side from the hydrostatic pressure acting on a given surface area and a much higher stress on the outlet side acting on a much smaller area provided by the nozzle cap; and said high stress state acting on outlet end of orifice provides sealing of the high pressure fluid and prevents leakage when the orifice is seated on a lapped surface of the nozzle cap.

5. A waterjet orifice assembly according to claim 1 wherein: the said spring disk provides for a configuration in which multiple orifices may be installed and retained in a manner similar to a single orifice described above.

6. A waterjet orifice assembly according to claim 1 wherein: the said spring disk and orifice(s) may be replaced readily and simply by operating personnel by removal of the nozzle cap, replacement of the orifices in the spring disk without any special requirements, and replacement of the nozzle cap.

7. A waterjet assembly consisting of: a spring disk with a central hole; an orifice; a nozzle cap attached to the water body; and orifice sits in nozzle cap counterbore.