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

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•The standoff distance should be kept within 12 mm to achieve: - Increased volume removal rates - Reduced noise levels •The traverse speed should exceed a critical value, which depends on a wide range of parameters. Speeds in excess of 16 mm/s should be used. •The shape of the cut produced by a single jet traverse is significantly affected by standoff distance and traverse rate. More geometrical characterization requires further research. MULTIPLE-PASS MILLING TESTS Experimental Apparatus and Parameters An in house six-axis robot was used to traverse an abrasive-waterjet nozzle. The use of this robot was limited in this phase to milling simple cavity shapes. Figure 9 shows the different components of the experimental setup. Samples to be milled were placed in the catcher tank. A rubber shield was fastened to the nozzle to control any splashing back of the jet. Figure 9. Test set-up for milling experiments The parameters used for milling are: Pressure 172 MPa Waterjet diameter 0.356 mm Type of abrasive garnet, silica sand, glass beads Size of abrasive particles mesh Nos. 60, 80 150 11
Abrasive flow rate 7.5 g/s (maximum) Traverse speed 420 mm/s Standoff distance 12 mm The lateral spacing of the jet was an additional parameter for the milling tests. A simple pattern was stored in the robot's controller to traverse simply in one direction, to shift the jet by a precise lateral increment, and then to traverse in the opposite direction. This scheme was used to simulate a continuous traverse as would be used in an actual milling process. To avoid excessive manipulator programming, masking plates were cut with the cavity shape to be milled. When the jet is traversed across such plates only, the cut shape will be milled in the masked material. Mild steel plates were used to mask aluminum, titanium, glass and graphite composite. The jet traverse can then overlap the cavity on the masking plate. Parameters were varied to determine their effect on the topography of the surfaces produced. The following is a discussion of the findings. Effect of Abrasive Material The strategy of milling with abrasive waterjets may include the use of different abrasive materials. The use of hard abrasives would be suitable for fast material removal rates. The use of soft frangible abrasives may be suitable for finishing. Two types of tests were conducted as discussed below. The first explored the use of alternating the abrasive materials for cutting and then finishing, and the second examined the effects of specific materials on surface topography. Use of Alternative Abrasives for Finishing Cavities were machined using typical garnet sand mesh No. 60 for fast material removal rates with side increments equal in size to one-half the jet diameter (d j =1 5 mm) A total of 20 parallel cuts (a total width of, 15.24 mm) were made, and the whole sequence was repeated four times (passes) to produce a relatively deep cavity. The depth of the cavity varied within 2.5 mm. When silica sand was used to finish the cavity and improve the depth uniformity, no positive results were gained. On the contrary, the depth variation became 3 mm after two passes using a pattern traverse, although the traverse speed was kept the same at 34 mm/s. The use of glass beads gave similar results to those of silica sand. It is concluded that depth uniformity control should be considered right at the beginning of the milling process. Irregularities produced by one pass or traverse are not corrected in the subsequent passes but rather exaggerated. A different pattern of traverse on every pass will complicate the milling process. Single passes of 20 adjacent cuts, as discussed above, were made on aluminum samples using garnet, silica sand and glass beads of comparable size (mesh No. 80). Figure 10 shows magnified photographs of the surfaces produced with these different materials. 12
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: Table 3. Material removal rate and
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 and 44: 500 psig and 6,000 psig. Compressiv
Page 45 and 46: Figure 6. STATIC IMPACTS ON COMMERC
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
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DYNAMIC CHARACTERISTICS OF WATERJET
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A piezoelectric transducer (Kistler
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From the data obtained, it is clear
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conjectured that this optimum signa
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difference of impact forces with an
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The pressure of the jet is not an i
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near the nozzle exit in the mixing
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etween 0.5 mm and 1.5 mm. Full- fie
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earlier observations that cavitatio
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Obstructed Conical Nozzle The nozzl
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CONSIDERATIONS IN THE DESIGN OF A W
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An experimental mechanism was desig
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horn and the modification of the st
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ased on more detailed examination o
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DEVELOPMENT OF CAVITATING JET EQUIP
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hole, a total 23 minutes was requir
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from 1.5 to 4 ft to be cut. Other f
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Table 2 Summary of CCPC Pavement Cu
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All of the experimental modules wer
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Figure 10. Effect of CAVIJET R cutt
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HYDRO DEMOLITION - TECHNOLOGY FOR P
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Figure 1. Air entrained concrete pr
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TABLE II used a mean rating because
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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
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ABRASIVE-WATERJET AND WATERJET TECH
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Commercial nuclear power plant deco
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Figure 3. Components of rotating no
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shroud and catching system designed
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Figure 9. Effect of abrasive size.
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alternative abrasive material. The
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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
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Figure 1 Kerf test stand pressure v
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Figure 3 Kerf area versus standoff
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The ratio of kerf depth to width or
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where: x c = u o d o ( ) (1) 4v e l
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Depending on the rock type γ can v
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CONICAL WATER JET DRILLING W. Dicki
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feed line. A conical cutting fluid
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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
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Figure 4: Diagram illustrating the
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The picture changes dramatically wh
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Analysis of the residuals of these
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5. Hood, M., "Cutting Strong Rock w
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hundred feet-per-second. At these v
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Figure 1. Typical Nozzle Configurat
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Figure 5. Expanded Signal from an I
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where: V w = water velocity F = mea
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HYDRO-ABRASIVE CUTTING HEAD—ENERG
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Figure 3. Percentage of initial abr
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Figure 6. Location of optimum recei
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WATER JET ASSISTED LONGWALL SHEARER
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• reduction of the proportion of
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The conversion set for the shearer
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into account. As far as possible no
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gal/yd 3 ). Another important influ
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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
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operating parameters (P. V tr , etc
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κ = permeability at 1 atm. pressur
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was substantial gain in the depth o
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Figure 9. Plot of exposure rate aga
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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
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Conventional rotary or percussive r
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A RELATIVE CLEANABILITY FACTOR A. F
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Relation [6] was used to derive the
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which has been observed for much of
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As part of a project to develop the
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Figure 1. Cost per square foot clea
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Abrasive Feed Rate The effect of ab
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Figure 4. Total cost per square foo
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3. Barker, C. R.; Mazurkiewicz, M.
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For our purposes here, we will lump
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Surface condensers can be cleaned b
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Some Powerlance customers have 20,0
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system could be designed that was o
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236
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ROTARY WATERBLAST LANCING MACHINES
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Motors and Gearing An advantage of
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The DuPont Company in LaPlace, Loui
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Fig 3 Heavy duty Rotary Lancing Mac
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D L - lower diameter of through hol
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Figure 1. A - single-pass, rough ke
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The erosion process is stochastic i
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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
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Figure 12. Transients of HAJM cycli
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T A = (f, h o, p, s o, f o, c, . .
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SURFACE FINISH CHARACTERIZATION IN
Page 269 and 270:
FIG. 2 Force Sensor Designed for Cu
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system can be used in the developme
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Figure 8 Cutting Force versus Cutti
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nearly at the center of the ceramic
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ABRASIVE WATERJET CUTTING OF METAL
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Figure 1. Experimental setup, inclu
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Figure 3. Scanning microphotograph
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Figure 8. Effect of cutting speed o
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a. Scanning microphotograph, lOOOx
Page 287 and 288:
c. Silicon image 1000x Figure 16. S
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