proceedings of the fourth us water jet conference - Waterjet ...

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eadily in tension than in compression, Ref. (15). This consideration applies both to the water hammer and ordinary impact load, but, since water hammer stresses are the larger, their tension effects are correspondingly greater and can propagate farther within the target. Figures 4, 5 & 6 give possible examples of this type of mechanism. The failures look as if the front face of the specimens were "pulled off." The traverses on granite shown in Figure 4 are extremely rough-looking. In Figure 5, the Percussive Jet has broken off a large piece from the face of the shale. All of the damage shown in these figures resembles brittle fracture as the material is removed in large pieces. The static impacts on brick shown in Figure 6 show the Percussive Jet induced failure within the front face of the brick. Figure 4. TRAVERSES ON GRANITE. Note rough-looking Percussive Jet cuts. At best, the conventional jet would only roughen the surface. Working pressure was 8000 psi. Figure 5. STATIC IMPACTS ON COALASSOCIATED SHALE. The Percussive Jet often induced massive failures as illustrated. The piece that was broken off has been replaced in this photograph. These impacts were about 2 seconds in duration at 4000 psi. 39
Figure 6. STATIC IMPACTS ON COMMERCIAL BRICK. These discharges were about 2 seconds in duration at 2300 psi pressure and illustrate massive-type failures induced by the Percussive Jet. Jet Persistence Discharge modulation and stream bunching can act to reduce jet momentum decay at long standoff distances. At standoffs greater than 100 jet diameters or so, jet velocity decreases rapidly with distance by aerodynamic drag, Ref. (16). In this decay, distance scales directly to discharge diameter so that, if discharge velocity and other factors are equal, the thicker the jet, the greater the momentum retained at given distance. The free stream diameter in Percussive Jets becomes progressively less uniform with distance, i.e., the bunching process, so that the jet may be loosely regarded as an alternation of two other jets with bigger and smaller discharge diameter than the actual. By this transformation, the jet momentum passes progressively into the bigger jet component, where it is less subject to aerodynamic decay. Thus, the Percussive Jet should retain momentum better than the same discharge un-modulated. Of course, this viewpoint is highly simplified. References t7) and (8) discuss the phenomenon in more detail. This jet persistence consideration is not as important for small cutting jets which are ordinarily used at standoffs under 100 diameters and suffer little velocity decay. In big jet applications, however, long range is highly desirable so that the jets are used up to distances involving severe velocity decay. Any of the favorable Percussive Jet impact characteristics discussed above can increase the effective range, but in the case of jet persistence, the range benefit is direct, i.e., velocity decay is deferred to greater distances. Furthermore, the velocity itself, or force exerted at impact, may not be the relevant parameter for jet performance, but rather some higher power of velocity, e.g., pressure against the target or hydraulic power per unit area. In the latter case, the benefits of improved jet persistence are correspondingly greater. Figure 7 1 shows examples of better jet persistence using Percussive Jets. Fivesecond duration firing of Percussive Jet and conventional jet were made side-by-side at 2000 psig discharge pressure. The block was 45 feet (1080 nozzle diameters) from the nozzle. The small hole in the upper left-hand side was made by a conventional jet and 1 EDITORIAL NOTE – THIS FIGURE WAS NOT SUPPLIED WITH THE MANUSCRIPT. 40
Page 1 and 2: PROCEEDINGS OF THE FOURTH U.S. WATE
Page 3 and 4: FOREWORD The U.S. Water Jet Confere
Page 5 and 6: FIELD APPLICATIONS- MINING Water Je
Page 7 and 8: Figure 1. Abrasive-Waterjet Nozzle
Page 9 and 10: N2 = ⋅ 2 d 2 j mav N = 3 N 4 Sett
Page 11 and 12: • Although reasonable correlation
Page 13 and 14: Effect of Traverse Speed Increasing
Page 15 and 16: Table 3. Material removal rate and
Page 17 and 18: Abrasive flow rate 7.5 g/s (maximum
Page 19 and 20: where u is the traverse rate in mm/
Page 21 and 22: Table 4 shows the results of additi
Page 23 and 24: this technique. The technique is al
Page 25 and 26: 12. Preece, C., editor, "Treatise o
Page 27 and 28: experiment was carried out to exami
Page 29 and 30: of changes in jet pressure, nozzle
Page 31 and 32: D = 0.0911 P 1.42 n 1.37 V −0.39
Page 33 and 34: Figure 8. Average Specific Energy V
Page 35 and 36: with the density of the material, o
Page 37 and 38: PERCUSSIVE JETS—STATE-OF-THE-ART
Page 39 and 40: This process of discharge modulatio
Page 41 and 42: has been demonstrated on all types
Page 43: 500 psig and 6,000 psig. Compressiv
Page 47 and 48: not pursued because frequency, ampl
Page 49 and 50: 12. Ponchot, W.D., "Hydrodynamic Mo
Page 51 and 52: THEORETICAL ANALYSIS AND EXPERIMENT
Page 53 and 54: D.Rockwell, E.Naudascher, Thomas an
Page 55 and 56: Fig. 3 Flow model Hence we can comp
Page 57 and 58: amplitude decreases suddenly when c
Page 59 and 60: Where T: wave function period If we
Page 61 and 62: Fig.14 Variation of dimensionless r
Page 63 and 64: EXPERIMENTAL RESULT ANALYSIS (1) Th
Page 65 and 66: Fig.19 Amplification factor versus
Page 67 and 68: DYNAMIC CHARACTERISTICS OF WATERJET
Page 69 and 70: A piezoelectric transducer (Kistler
Page 71 and 72: From the data obtained, it is clear
Page 73 and 74: conjectured that this optimum signa
Page 75 and 76: difference of impact forces with an
Page 77 and 78: The pressure of the jet is not an i
Page 79 and 80: near the nozzle exit in the mixing
Page 81 and 82: etween 0.5 mm and 1.5 mm. Full- fie
Page 83 and 84: earlier observations that cavitatio
Page 85 and 86: Obstructed Conical Nozzle The nozzl
Page 87 and 88: CONSIDERATIONS IN THE DESIGN OF A W
Page 89 and 90: An experimental mechanism was desig
Page 91 and 92: horn and the modification of the st
Page 93 and 94: ased on more detailed examination o
Page 95 and 96:
DEVELOPMENT OF CAVITATING JET EQUIP
Page 97 and 98:
hole, a total 23 minutes was requir
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from 1.5 to 4 ft to be cut. Other f
Page 101 and 102:
Table 2 Summary of CCPC Pavement Cu
Page 103 and 104:
All of the experimental modules wer
Page 105 and 106:
Figure 10. Effect of CAVIJET R cutt
Page 107 and 108:
HYDRO DEMOLITION - TECHNOLOGY FOR P
Page 109 and 110:
Figure 1. Air entrained concrete pr
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TABLE II used a mean rating because
Page 113 and 114:
As work loads grew and costs escala
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inches deep of deteriorated bridge
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Figure 6. Atlas Copco Conjet removi
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6. Total Ownership Cost Per Day $ 9
Page 121 and 122:
ABRASIVE-WATERJET AND WATERJET TECH
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Commercial nuclear power plant deco
Page 125 and 126:
Figure 3. Components of rotating no
Page 127 and 128:
shroud and catching system designed
Page 129 and 130:
Figure 9. Effect of abrasive size.
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alternative abrasive material. The
Page 133 and 134:
four arms leading to nozzle holders
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surrounding grout, they tended to r
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12. Hashish, M. “Steel Cutting wi
Page 139 and 140:
Figure 1 Kerf test stand pressure v
Page 141 and 142:
Figure 3 Kerf area versus standoff
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The ratio of kerf depth to width or
Page 145 and 146:
where: x c = u o d o ( ) (1) 4v e l
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Depending on the rock type γ can v
Page 149 and 150:
CONICAL WATER JET DRILLING W. Dicki
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feed line. A conical cutting fluid
Page 153 and 154:
A second series of tests at the ful
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Figure 8. 6061-T6 aluminum cut with
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serves to reduce tool wear (8). It
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Traverse speed is the velocity of t
Page 161 and 162:
Figure 4: Diagram illustrating the
Page 163 and 164:
The picture changes dramatically wh
Page 165 and 166:
Analysis of the residuals of these
Page 167 and 168:
5. Hood, M., "Cutting Strong Rock w
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hundred feet-per-second. At these v
Page 171 and 172:
Figure 1. Typical Nozzle Configurat
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Figure 5. Expanded Signal from an I
Page 175 and 176:
where: V w = water velocity F = mea
Page 177 and 178:
HYDRO-ABRASIVE CUTTING HEAD—ENERG
Page 179 and 180:
Figure 3. Percentage of initial abr
Page 181 and 182:
Figure 6. Location of optimum recei
Page 183 and 184:
WATER JET ASSISTED LONGWALL SHEARER
Page 185 and 186:
• reduction of the proportion of
Page 187 and 188:
The conversion set for the shearer
Page 189 and 190:
into account. As far as possible no
Page 191 and 192:
gal/yd 3 ). Another important influ
Page 193 and 194:
At approximately 2 m/s (393 fpm), a
Page 195 and 196:
Proceedings of the 8th Internationa
Page 197 and 198:
κ = permeability of rock at atmosp
Page 199 and 200:
operating parameters (P. V tr , etc
Page 201 and 202:
κ = permeability at 1 atm. pressur
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was substantial gain in the depth o
Page 205 and 206:
Figure 9. Plot of exposure rate aga
Page 207 and 208:
For nozzle C2, a = 0.5 x 10 4 and b
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204
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Deep drilling or slotting requires
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imparted by an air motor coupled to
Page 215 and 216:
Conventional rotary or percussive r
Page 217 and 218:
A RELATIVE CLEANABILITY FACTOR A. F
Page 219 and 220:
Relation [6] was used to derive the
Page 221 and 222:
which has been observed for much of
Page 223 and 224:
As part of a project to develop the
Page 225 and 226:
Figure 1. Cost per square foot clea
Page 227 and 228:
Abrasive Feed Rate The effect of ab
Page 229 and 230:
Figure 4. Total cost per square foo
Page 231 and 232:
3. Barker, C. R.; Mazurkiewicz, M.
Page 233 and 234:
For our purposes here, we will lump
Page 235 and 236:
Surface condensers can be cleaned b
Page 237 and 238:
Some Powerlance customers have 20,0
Page 239 and 240:
system could be designed that was o
Page 241 and 242:
236
Page 243 and 244:
ROTARY WATERBLAST LANCING MACHINES
Page 245 and 246:
Motors and Gearing An advantage of
Page 247 and 248:
The DuPont Company in LaPlace, Loui
Page 249 and 250:
Fig 3 Heavy duty Rotary Lancing Mac
Page 251 and 252:
D L - lower diameter of through hol
Page 253 and 254:
Figure 1. A - single-pass, rough ke
Page 255 and 256:
The erosion process is stochastic i
Page 257 and 258:
three dimensional controlled erosio
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This can only be regarded as a simp
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approximately zero. Time constant T
Page 263 and 264:
Figure 12. Transients of HAJM cycli
Page 265 and 266:
T A = (f, h o, p, s o, f o, c, . .
Page 267 and 268:
SURFACE FINISH CHARACTERIZATION IN
Page 269 and 270:
FIG. 2 Force Sensor Designed for Cu
Page 271 and 272:
system can be used in the developme
Page 273 and 274:
Figure 8 Cutting Force versus Cutti
Page 275 and 276:
nearly at the center of the ceramic
Page 277 and 278:
ABRASIVE WATERJET CUTTING OF METAL
Page 279 and 280:
Figure 1. Experimental setup, inclu
Page 281 and 282:
Figure 3. Scanning microphotograph
Page 283 and 284:
Figure 8. Effect of cutting speed o
Page 285 and 286:
a. Scanning microphotograph, lOOOx
Page 287 and 288:
c. Silicon image 1000x Figure 16. S
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