WATER JET CONFERENCE - Waterjet Technology Association

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DISCUSSION OF TEST RESULTS Jet Configuration In the case of post-orifice entrainment of abrasives to generate high-capability abrasive waterjet, the aspect of abrasive entrainment is very important as the coherence of waterjet and abrasive entrainment are conflicting issues. With Fluidyne's nozzles, the issue of abrasive entrainement is related to the jet configuration, which denotes the number of waterjets, size and geometries of orifices, and the physical arrangement of orifices. In order to study the aspects of abrasive entrainment, Fluidyne prepared orifice cones of many configurations. The number of orifices on each orifice cone varied from one to nine. Some were designed to issue parallel jets while others were designed to produce converged jets. Orifice cones of similar configuration also have orifices of different sizes for operating at different pressure levels and flow rates. Testing these orifice cones on concrete revealed that abrasive entrainment is significantly better with orifice cones having five or more waterjets, as judged by the amount of abrasives introduced without choking and the depth of cuts produced. The 5-parallel-jet nozzle, for example, was also found to be superior than a single-jet nozzle of similar output in cutting concrete without abrasives. This observation may be explained by the cavitating actions of the 5-jet bundle as the five individual waterjets will form a single cavitating jet when they reached the target material. In comparison, a 5-parallel-jet nozzle can entrain more abrasives than its converging-jet counterpart. The cuts made by parallel-jet nozzles are wider. On the other hand, converging-jet nozzles can make narrower and deeper cuts at reduced abrasive consumption rates than their parallel-jet counterparts. Rock Specimens The test results showed that the performance of Abrasion Jet in cutting rock is much influenced by the type of rock involved. Figure 3 presents a comparison of cut depth obtained with various rock specimens, with or without abrasives. The benefit of adding abrasives into the waterjet is clearly demonstrated and the effect of rock properties on depth of cut is also very well indicated in this data. The ratio of depth of cut obtained with and without abrasives can vary from 5 for soft sandstone to more than 15 for hard quartzite and basalt. This depth ratio on hard rock is even greater when the Abrasion Jet was applied at slow nozzle traverse speed or when multiple passes were applied. It is believed that the depth of cut on rock with Abrasion Jet may indicate the hardness and/or grain structure of the rock involved if one can precisely control the flow of a chosen abrasive. It could be a useful method for studying and classifying various rock types as it is easier to perform than conventional compressive-strength tests. However, more understanding on the cutting mechanism of Abrasion Jet is necessary before this process could be standardized. Effect of Abrasives The type of abrasives used, its grain size and shape, and the mass flow rate all intimately influence the rock cutting capability of the abrasion Jet. This aspect, unfortunately, has not been studied in depth to date in this project. Garnet abrasives have shown to be far superior to silica sand, copper slag and "Green Diamond" abrasives in cutting concrete and rock. This observation can be explained if one compares the relative hardness of these abrasives and observe the shape of the grains under a microscope. Garnet grains are sharper and have several cutting edges owing 441
to their crystalline structure. The grains of some beach sands, on the other hand, are well polished and have lost their sharp edges. The presence or absence of natural fractures on the abrasive grains is also a related factor. The benefit of using hard and sharp abrasives was found to be influenced by the rock involved. For cutting sandstone, the difference in cut depth between garnet and copper slag was not significant. In cutting quartzite, garnet was far superior to copper slag. For the same reason, garnet and silicon carbide probably produce similar cutting results on quartzite but can be significantly different when they are used to cut glass or steel. The relative hardness between the abrasives and the target material is a subject relevant to Abrasion Jet cutting of materials. This subject is believed to be related to some other factors, such as water pressure. Using garnet as abrasives, the grain size was found to affect the cutting rate of Abrasion Jet, as shown in Figures 4 and 5. Garnet of Grit #36 and #60 were superior to #100 in cutting quartzite specimens. Grit #60 was found to be slightly superior to Grit #36 in cutting quartzite but the reverse was observed with other types of rock. The study of abrasive grain size's effect on Abrasion-Jet cutting was complicated by the fact that changing the abrasive grain size can change the amount of abrasives entrained into the multiple waterjets and thus the gravity flow of abrasives at the tank. A slight change in the abrasive flow rate can affect the depth of cut such that the observation of the effect of other factors becomes difficult. With #100 garnet, choked abrasive flow occurred early and a maximum amount of only 3 pounds per minute was able to be introduced into the nozzle. Also, the benefit in cutting with #100 garnet was seen to level off early at about 2.0 pound per minute. With the same nozzle but #36 and #60 garnet, the abrasive feed rate could be increased up to 4.0 pound per minute and the benefit in cutting increased with the increase in feed rate until abrasive flow was choked. The reason for the occurrence of choked abrasive flow is not yet clearly understood but is believed to be related to the water flow rate and jet configurations. It has been observed that the abrasive feed rate could be increased beyond 5 pound per minute with the same abrasives and abrasive orifice when a different 5-parallel jet orifice cone was used. The only difference in these two cases was the water flow rate. Obviously, the abrasives entered into the mixing cavity must be carried away immediately by the waterjets if accumulation and clogging of abrasives are to be avoided. How does the abrasive grain size affects the level of negative pressure generated in the mixing cavity is not clear at present. Garnet abrasives of different grit sizes produced cuts of different profile on rock, as shown in Figure 6, which presents a photograph of cuts made on a quartzite specimen. The cuts on the left were made with #60 garnet while those on the right were made with #36 garnet. The sharp taper exhibited by the cuts is associated with cutting very hard rock. The influence of spent jet is also visible on the rock specimen and is indicated by the bottom portion of the cuts. This aspect is associated with the impingement angle of Abrasion Jet, which can affect the depth of cut but has not been studied in this project. Nozzle Standoff Distance Within a range of a few inches, the nozzle standoff distance of Abrasion Jet does not have significant effect on the depth of cut on rock as it does in high-pressure waterjet cutting of 442
Page 1 and 2:
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
Page 398 and 399: K Ay = coefficient correcting for f
Page 400 and 401: Figure 1. Schemes of combined break
Page 402 and 403: Figure 5. Dependence of specific en
Page 404 and 405: Figure 12. Percentage of grade R -6
Page 406 and 407: Figure 1. Particle size analysis. T
Page 408 and 409: NAME: Dr. Henkel COMPANY: Bergbau-F
Page 410 and 411: presented. This study, of course, i
Page 412 and 413: identifying a general trend for the
Page 414 and 415: Effect of Abrasive Hardness, Shape
Page 416 and 417: 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 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 468 and 469: clog; there not being sufficient ar
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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