WATER JET CONFERENCE - Waterjet Technology Association

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clog; there not being sufficient area to allow the water and abrasive to escape without back pressure. The length of the discharge tube is not of such a critical nature and is usually in the order of 21/2" to 4" from the plenum chamber to discharge point into free air. CUTTING PARAMETERS. As well as factors which have already been discussed, such as outlet tube diameter, the rate of cut is also effected by the following Pressure: Generally the rate of cut is increased the higher the pressure is (Figure 17). Flow and nozzle size will also have their effect on the final performance. Standoff Distance: While it is generally true that the closer a cutting head is to the work piece the more efficient the cut, this cannot be carried to extremes. In the same way that too small a discharge tube will cause the head to back pressure and clog, the same thing will happen if the discharge tube is too close. This is particularly true if the head is at right angles to the work piece. For all practical purposes this means that the head should normally not be used closer than a 1/4” from the work piece. The maximum distance at which effective cutting can take place is determined by the operating pressure, coherance of the water jet and the horsepower of the power unit. As an example a 75 horsepower unit is capable of cutting through 4" steel plate, 18" of reinforced concrete and 10 X 8 'I' Beams in a single slow pass. Quantity of Abrasive. The rate and depth of cut are proportional to the amount of abrasive within certain limits. Above a certain point the performance drops off in the manner shown in Fig 4 as for abrasive cleaning heads. Abrasive Type. The cutting performance of various abrasives is shown in Fig.18. Again the cutting effect of copper slag and silicon carbide is similar with sand being a very inferior abrasive. CUTTING DATA: Steel Cutting. Figure '19' shows a .5" mild steel plate which has been slotted using a water abrasive cutting head. As in most cutting operations the head was angled in the direction of travel approximately 30°, so the deflected jet was carrying out a preliminary grooving cut. The slot tapered from approximately 1/4" on the entry side to 7/32" on the exit side of the cut. The quality of the cut with the absence of rough edges and burrs, as formed by flame cutting and abrasive wheels, is an ideal weld preparation for joining pipes and plates together. Stone Cutting. Fig.'20' shows a piece of Darley Dale Limestone slotted using water and abrasive. This sample was cut under the following conditions :2" thick Darley Dale Limestone cut at 36" per 461
minute, 8000 psi and 12 lbs copper slag per minute. Similar performance has been achieved in other soft rocks, such as sandstone while up to 2/3 this performance has been achieved in hard rocks such as Dakota Granite. Concrete Cutting. Figure '21' shows a piece of 2" thick concrete slab, with 1/4” reinforcing bars at 1" intervals. Cutting conditions were the same as for limestone except for traverse rate which was 15" per minute. Deflashing of Castings. The water abrasive cutting head may be used to remove flash, risers and fillers from complex castings. It leaves a finish free of burns and burnt on sand. It is particularly appropriate to the removal of mould bosses from investment casting in hard materials, such as high temperature aircraft alloys. Cutting of Hard Materials. Some work has been carried out on the cutting of hard materials, which are very difficult and expensive to cut using conventional techniques. 3/8" Chobham Armour plate may be cut at speeds up to 5" per minute using a 75 horsepower cutting head at 8000 psi. Similarly bars of nimonics, waspalloys and titanium alloys may be cut at speed similar to and in some cases faster than existing cut off machines. In these cases there is a viable economic justification once the cut width is reduced. The present cut width of just under 1/4” wastes too much of these expensive materials. Cutting in Hazardous Environments. Considerable work has been carried out by BHRA Fluid Engineering' into the use of water abrasive cutting heads in highly inflammable atmospheres. The cutting of steel and stone has been carried out in atmospheres containing explosive mixtures of methane, propane, acetylene, hydrogen and other highly inflammable gases. This work was carried out because cutting with a water jet and abrasive can generate sparks, which can be seen in a darkened environment. As they have never caused an ignition, it is thought that they were of too low an intensity to be of danger. Further works showed that far fewer sparks were generated when the abrasive was supplied as an aqueous slurry. The work was carried out in conjunction with the 'Safety in Mines Research Establishment' of the 'Health and Safety Executive'. While not giving a categorical guarantee of the inherent safety of such equipment, they are satisfied enough to wish for full in house tests within a mine. The equipment was also designed by 'BHRA' in conjunction with 'BP' for use on off shore oilwells in emergency cutting situations. The first set of equipment is now under construction for use on an offshore rescue vessel. 'BHRA's contribution to the development of abrasive systems in Europe has been considerable, in the form of wide angle clearing heads, slurry feeds, underwater systems, cutting systems in air and in explosive environments. 462
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Proceedings of the Second U.S. WATE
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Visualization of the Central Core o
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A Status Report on the Conceptual D
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SESSION 7 - CIVIL & INDUSTRIAL Chai
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Cutting Hard Rock With Abrasive-Ent
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frictional and piping component rel
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R = a1 ⋅ A1 A2 a2 I = 2H o Q o
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attenuation of the output. The tran
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Figure 1. Branch System Modulator F
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Figure 5. Modulation Response for B
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Figure 9. Modulation response for s
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can be used for any form of input.
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with a cylindrical shape to the jet
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m/s. The range of power found from
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Figure 3. Power vs nozzle diameter
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Figure 5. Frequency vs length of th
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NAME: Gerald Zink COMPANY: StoneAge
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modulatornozzle assembly. The ordin
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DISCUSSION OF FLUID MECHANICS The i
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This process serves to protect the
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For test purposes, these concrete b
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REFERENCES CITED 1. Barker, C. R.,
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FIGURE 4. INNER CORE OF PERCUSSIVE
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FIGURE 9. EXAMPLE OF HIGH-PRESSURE
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NAME: John E. Wolgamott COMPANY: St
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THE FOCUSED SHOCK TECHNlQUE FORPROD
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The reflected wave is thus also cyl
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neglected. The introduction of a co
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DISCUSSION NAME: George Savanick CO
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H’ mean shape factor Hj theoretic
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Required streamline curvature at th
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2 x 2 ≅ ( e − 2 p + w)/k2 (2-8)
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eliminating 2 n r 2 from equations
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approximation to the actual flow si
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skin friction coefficient but are c
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where: (H) = A1H 3 + A2H 2 + A3H +
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effect (< 0.5%) on coefficients of
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TABLE 5 Rei x 10 5 β 3 4 5 6 Po Po
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TABLE 6 D(mm) d o(mm) L t(mm) L f(m
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expanding rather than contracting a
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25. Weber, H.E., 1978, Boundary lay
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Figure 5. Wall velocity distributio
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Figure 9. Effect of nozzle design o
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Figure 12. CA+T Design Philosophy.
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Figure 16. Effect of inlet b 1 cond
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Figure 20. Relaminarization at nozz
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Figure 24. Pressure decay data. 88
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VISUALIZATION OF THE CENTRAL CORE O
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DISCUSSION Although employing the i
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5. Lambert, J. H., 1760, Photometri
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Figure 6. Spectral sensitivity curv
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NAME: W.C. Cooley COMPANY: Terraspa
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INTRODUCTION Pulsed liquid jets sho
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y=X ∨ P A dy = p p A p 2 (L c y=0
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Using equation (15), the value of X
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Thus about the first 10% of the dri
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Many design cases, including those
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surface spall occurred, resulting i
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Figure 3. Chamber pressure at pisto
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Figure 7. Effect of nozzle area rat
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Figure 11. Extrusion device schemat
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Figure 15. Typical chamber pressure
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DISCUSSION NAME: W. C. Cooley COMPA
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material which are, in turn, affect
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the water jet. This method was not
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where h is the depth of penetration
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obtained during this phase of the i
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observed that the smallest depth of
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Figure 2. Idealized Relationships b
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Figure 6. Penetration as a Function
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DEVELOPMENT OF VARIABLE DELIVERY TR
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THE STRUCTURE AND FUNCTION OF THE P
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The injection pressure can be contr
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ACKNOWLEDGEMENTS The authors gratef
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Figure 4. Theoretical required powe
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Figure 9. Variation of efficiency w
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THE "SKIPJACK" SEWER CLEANING NOZZL
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HYDRO-BLASTING SAFETY C.W. Adaway,
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Remember, your Hydro-Blasting work
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horizontal, sometimes vertical, and
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Figure 2. Safety Gear Figure 3. Tub
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DEVELOPMENTS IN CLEANING COKE OVEN
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causing chain breakages and the scr
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was encountered, then the rotation
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(C) Capital Expenditure: Material i
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Figure 9. Swivel coupling Figure 10
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OPTIMIZING JET CUTTING POWER FOR TU
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PRESSURE DROP (psi) ELEMENT Cv @10
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power output. Undersized nozzles re
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Subscripts n - Nozzle p - Pump t -
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Figure 1. Cutting effect as a funct
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CONSIDERATIONS IN THE COMPARISON OF
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pressure can be lowered to perhaps
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Figure 2: Fan jet issuing from a no
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DISCUSSION NAME: John Griffiths COM
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where Q = Flow rate - gpm D = Jet O
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Again, not limited to Newtonian flu
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REFERENCES 1. Brown, R.W. and Loper
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Table 2. Jet Cleaning Speeds and ot
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ANSWER: The utilization of the stat
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complexity and short component life
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Figure 4, for ap values ranging fro
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Decontamination Methods for rapidly
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a. “PULSER” b.”ORGAN-PIPE”
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Figure 5 - Removal rate for various
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DISCUSSION NAME: David A. Summers C
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DRILLING BORE HOLES IN COAL MINES U
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pile could not be judged as represe
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DISCUSSION NAME: David Summers COMP
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HYDRAULIC MINING EXPERIMENTS IN AN
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The monitor was fed pressurized wat
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The IH rig was considered to be sup
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REFERENCES 1. Okhrimenki, V. A., A.
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Figure 2. Jet cutting sandstone at
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Figure 5. Schematic plan view of In
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Figure 7. Suction Box. 226
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USE OF HIGH PRESSURE WATER JETS FOR
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flame torch to cut this block, redu
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the order of 360 rpm. Under these c
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Figure 3. Slot cut by jet at 11 o s
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JET-MINER SURFACE AND IN-SEAM TRIAL
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The hydraulic drive of the haulage
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The surface trials had have the obj
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Figure 2. Experimental version. Fig
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Figure. 7 Jet-Miner prototype Figur
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SOME PATTERNS OF TECHNOLOGY TRANSFE
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Development of High Pressure_Techno
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configurations, the design of an op
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and public sectors. After a haitus
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Souder, W.E. and Evans, R.J., "The
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Figure 5. Technological achievement
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Table 3. Perceived disadvantages of
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already been, or is being applied w
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Using the requirements profile and
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ant hose combination, a guiding sys
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HYDRAULIC MINING TESTS Site selecti
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SAFETY All operations were carried
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TABLE V. Categories of Jet Mining D
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Figure 2. Generalized geologic prof
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SECONDARY FRAGMENTATION WITH WATER
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do possess a maximum point (Fig. 8)
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Figure 4. Rossin-Rammler plot. Figu
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Figure 8. Non-dimensional plot for
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HYDRAULIC COAL MINING SYSTEM Typica
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Figure 4. (From ref. 1) DISCUSSION
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INTRODUCTION Developing an unique t
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The coefficients "b " in Eq. (1) ca
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By the end of 1982, a total of more
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Figure 4. Cutting ability of swing-
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Figure 10. An operating performance
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for an abrasive, the abrasive parti
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the particles, while at slower spee
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to break away the remaining segment
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Table 1. Concrete saw technology. T
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NAME: Tom Brunsing COMPANY: Foster-
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FEASIBILITY STUDY OF CUTTING SOME M
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hydraulic power required to cut thr
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pressure was varied from 103 to 310
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2.1 Heading and gutting fresh cod f
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Figure 5. The cuts surface of a blo
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Figure 17. Cuts made across the cla
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JET NOTCHING USED IN THE CONSTRUCTI
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Bottom notch diameter was determine
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σ H = in-situ stress in the horizo
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Figure 3. Final block displacement.
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Figure 8. Comparison of Slurry Pump
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THE FURTHER DEVELOPMENT OF AN UNDER
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use taps or hydrants. To achieve th
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supply line. It was determined that
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The rotating head requires major mo
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Figure 4. System field test set-up
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Figure 10. Bentonite drilled clay s
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MECHANICAL TOOLS Cutting Tool Energ
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Ψ = cos −1 ⎧ ⎪ ⎪ ⎨ ⎪
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mode also contributes to chip flush
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NAME: Simon Johnson COMPANY: Newcas
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ROLLER TOOLS COMBINED WITH HIGH-PRE
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Various designs and applications ar
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Figure 1. Full-face tunneling machi
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Figure 11. roadway profile cutting
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Figure 19. High-pressure water jet
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DESIGN AND OPERATION OF TWO LARGE-S
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The hydraulic system for the thrust
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Results of Trial Tests As part of m
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cutting rates, degree of bit wear,
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Overall approximate Weight: Basic M
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Figure 5. 3 ft. diameter laboratory
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nozzle diameter and cutting speed w
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2. Cutting Speed The influence of c
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energy it effects an increase in me
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Tip angle (degrees) 87 Off-set angl
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Figure 5. Figure 6. Figure 7 Figure
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Figure 17. Figure 18. Figure 19. Fi
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SCHEMES OF COAL MASSIF BREAKAGE BY
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out thoroughly an efficient scheme
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Research analysis has proved that t
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DEPENDENCE OF POWER INDICES OF COMB
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The experiments have shown how the
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K Ay = coefficient correcting for f
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Figure 1. Schemes of combined break
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Figure 5. Dependence of specific en
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Figure 12. Percentage of grade R -6
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Figure 1. Particle size analysis. T
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NAME: Dr. Henkel COMPANY: Bergbau-F
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presented. This study, of course, i
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identifying a general trend for the
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Effect of Abrasive Hardness, Shape
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In some situations, especially in c
Page 418 and 419: Figure 1. Abrasive waterjet nozzles
Page 420 and 421: Figure 8. Effect of standoff distan
Page 422 and 423: Figure 13. Abrasive waterjet cuts i
Page 424 and 425: CUTTING WITH ABRASIVE WATERJETS M.
Page 426 and 427: 3.3 Abrasive Feed Systems For abras
Page 428 and 429: Because of the large number of infl
Page 430 and 431: due to wear. Although actual operat
Page 432 and 433: from this new technology. Table 2 l
Page 434 and 435: Table 1. materials cut by abrasive
Page 436 and 437: Figure 1. Abrasive waterjet nozzles
Page 438 and 439: a) kerfs in mild steel b) S.S. 15.5
Page 440 and 441: a) circle cutting in glass b) lamin
Page 442 and 443: DISCUSSION NAME: Andrew F. Conn COM
Page 444 and 445: CUTTING HARD ROCK WITH ABRASIVE-ENT
Page 446 and 447: slurry nozzle. Testing at water pre
Page 448 and 449: DISCUSSION OF TEST RESULTS Jet Conf
Page 450 and 451: materials. The flexibility in nozzl
Page 452 and 453: pressure can be wiped out if diffic
Page 454 and 455: 9. Maurer, W.C., and Heilheckler, J
Page 456 and 457: Figure 5. Effect of abrasive feed r
Page 458 and 459: Figure 9. Accumulated depth of mult
Page 460 and 461: Figure 13. Close-up view of quartzi
Page 462 and 463: ABRASIVE INJECTION USAGE IN THE UNI
Page 464 and 465: sudden changes in the feed rate eff
Page 466 and 467: or the abrasive must be manually to
Page 470 and 471: CODE OF PRACTICE FOR THE USE OF ABR
Page 472 and 473: Figure 5. Water abrasive cleaning h
Page 474 and 475: Figure 15. 360 0 abrasive pipe clea
Page 476 and 477: ECONOMIC CONSIDERATIONS IN WATER JE
Page 478 and 479: Other criteria to be considered in
Page 480 and 481: 3 MANUAL METHODS OF JET CLEANING &
Page 482 and 483: contractor with old, unsafe, equipm
Page 484 and 485: Figure 1. Showing the increased cos
Page 486 and 487: Figure 8. Automatic tube bundle cle
Page 488 and 489: ackground to the subsequent coopera
Page 490 and 491: The molecules of SUPER-WATER posses
Page 492 and 493: shaken just before use. SUPERWATER
Page 494: 26. Bednarz, L.P., "Effects of Poly
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