Studies of the frictional heating of polycrystalline diamond compact drag tools during rock cutting

Technical Report · Tue Jun 01 00:00:00 EDT 1982

DOI:https://doi.org/10.2172/5281848· OSTI ID:5281848

Ortega, A; Glowka, D A

A numerical-analytical model is developed to analyze temperatures in polycrystalline diamond compact (PDC) drag tools subject to localized frictional heating at a worn flat area and convective cooling at exposed lateral surfaces. Experimental measurements of convective heat transfer coefficients of PDC cutters in a uniform crossflow are presented and used in the model to predict temperatures under typical drilling conditions with fluid flow. The analysis compares favorably with measurements of frictional temperatures in controlled cutting tests on Tennessee marble. It is found that average temperatures at the wearflat contact zone vary directly with frictional force per unit area and are proportional to the one-half power of the cutting speed at the velocities investigated. Temperatures are found to be much more sensitive to decreases in the dynamic friction by lubrication than to increases in convective cooling rates beyond currently achievable levels with water or drilling fluids. It is shown that use of weighted drilling fluids may actually decrease cooling rates compared to those achieved with pure water. It is doubtful that tool temperatures can be kept below critical levels (750/sup 0/C) if air is employed as the drilling fluid. The degree of tool wear is found to have a major influence on the thermal response of the friction contact zone, so that for equal heating per contact area, a worn tool will run much hotter than a sharp tool. It is concluded that tool temperatures may be kept below critical levels with conventional water or mud cooling as long as the fluid provides good cutter-rock lubrication.

• Research Organization: Sandia National Lab. (SNL-CA), Livermore, CA (United States)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5281848
• Report Number(s): SAND-80-2677; ON: DE82018632
• Country of Publication: United States
• Language: English

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15 GEOTHERMAL ENERGY
GEOTHERMAL WELLS
ROCK DRILLING
CUTTING
CUTTING TOOLS
DIAMONDS
DRILL BITS
DRILLING FLUIDS
FRICTION
HEAT TRANSFER
ISOTHERM
LUBRICATION
MATHEMATICAL MODELS
ROCK MECHANICS
WEAR
CARBON
DRILLING
DRILLING EQUIPMENT
ELEMENTAL MINERALS
ELEMENTS
ENERGY TRANSFER
EQUIPMENT
FLUIDS
MACHINING
MECHANICS
MINERALS
NONMETALS
TOOLS
WELLS
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