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Reducing the mass of the rolling elements in ball bearings causes a reduction of centrifugal forces and thereby extends bearing fatigue life. Ball mass is reduced by drilling a concentric hole through each ball. Concentricity and finish of the drilled hole can be closely controlled and the balls accurately balanced.
Two rotary diamond bit designs, one operating with a chip-flushing fluid, the second including auger section to remove drilled chips, enhance usefulness of tool for exploratory and industrial core-drilling of hard, abrasive mineral deposits and structural masonry.
Drilling tests for evaluating coring potential of Apollo lunar surface drill titanium core stems
Data are presented, covering drilling techniques, factors affecting penetration rates, cost estimation, and system improvement. Various drill bits are also discussed.
Several planetary rock corers and drill design concepts have been developed for obtaining subsurface rock samples in future planetary explorations. Tools are designed for unmanned space vehicles. Two devices are rotary impact multiple chisel trepan rock corer and hole drilling tool.
An experimental stress analysis was undertaken to evaluate stresses within cylindrically hollow (drilled) bearing balls proportioned for 40, 50, and 60 percent mass reductions. Strain gage rosettes were used to determine principal strains and stresses in the steel ball models statically loaded in various orientations. Results are reported for 127 mm OD balls under 44,500 N loads. Similitude considerations permit these results to be applied to calculate stresses in actual size drilled bearing balls proportioned to these mass reductions.
Abundances and isotopic compositions of all the stable noble gases (He, Ne, Ar, Kr, Xe) were measured at different depths of the Apollo 15 and Apollo 16 deep drill cores, and in several surface fines and breccias. All samples analyzed from both drill cores were found to contain large concentrations of solar wind implanted gases. This means that even the deepest layers of both cores have experienced a lunar surface history. The Apollo 15 core data are consistent with a combined accretion plus static time of a few hundred million years, and also indicate variable pre-accretion irradiation of core material. Depth profiles of cosmogenic gases in the Apollo 16 core show considerably larger concentrations of cosmic gases below 65 cm depth than above. This pattern may be interpreted either as an accretionary process, or by a more recent deposition of regolith to the upper 70 cm of the core.
Stresses in dimensionally similar large models of 40-, 50- and 60-percent mass reduction cylindrically hollow 'drilled' bearing balls were experimentally evaluated with flat strain gage rosettes. Dimensionless principal stress coefficients were calculated and were applied to estimate the bending stresses in the drilled balls of three series of full-scale bearing experiments. Stresses were highest when the applied load approached the edge of the hole, and ranged up to almost 620 million Newtons per sq m at the bore.
Instructions are given for using the DRILL computer program which converts data contained in an Interactive Computer Graphics System (IGDS) design file to production of a paper tape for driving a numerically controlled drilling machine.
Contacts in drill stem 60002 which indicate layers at least several centimeters thick and with one firm age of about 2.5 x 10 to the 7th yr are observed on the basis of characteristic patterns of track density variation with depth from the contact. The patterns can be observed primarily because the drill stem has a large immature component (path II soils).
Ferromagnetic resonance and magnetic hysteresis loop measurements were performed on 212 samples from the Apollo 16 deep drill core. The total iron content is generally uniform with a mean value of 5.7 plus or minus 0.9 wt%. The soils range in maturity from immature to mature. Two major contacts were observed. The contact at 13 cm depth represents a fossil surface whereas the contact at 190 cm depth has no time-stratigraphic significance. The data suggest that the core section below 13 cm depth was deposited in a single impact event and subjected to meteoritic gardening for about 450 m.y. However, our data do not preclude deposition by a series of closely spaced events. About 50 m.y. ago, the top 13 cm were added. Comparison with the Apollo 16 double drive tube 60009/60010 does not yield any evidence for a stratigraphic correlation with the deep drill core.
On the basis of modal petrography the upper, mare basalt-rich portion of the Apollo 17 drill core (sections 70007, 70008, 70009) can be subdivided into three major stratigraphic units. The lower unit (a) falls within 70007, is relatively mature, and contains evidence of an increase in highland component and decrease of mare component within the lower approximately 8 cm. The middle unit (b) is coarse-grained and relatively immature; this unit has the highest concentration of mare basalt lithic and mineral fragments and mare orange/black glasses. The top unit (c) falls within 70009 and is relatively mature. Within these three sections of the drill core, there are compositional clusters of glass beads that correspond to high Ti subfloor basalt (orange/black glass), anorthositic gabbro (clear glass), and a new very low Ti (VLT) mare basalt (yellow/green glass).
Device installs plugs and then drills them after sandwich face sheets are in place. Template guides drill bit into center of each concealed plug thereby saving considerable time and fostering weight reduction with usage of smaller plugs.
Instrumental neutron activation analysis was used to examine 34 major, minor and trace elements in 48 bulk soils and size fractions (90-1000 microns, 20-90 microns and less than 20 microns) of the Apollo 17 deep drill core sections 70009-70006 (upper 130 cm). Modal data were also obtained for the less than 20 micron size fraction. Preliminary results indicate that (1) the chemistry of the greater than 90 micron and 20-90 micron coarse fractions is identical but quite different from the less than 20 micron fine fraction; (2) the upper 50 cm of the drill core is highly enriched in mare material; (3) the dominant source of highland material is KREEPy instead of anorthositic; and (4) indigenous volatiles such as Zn are quite high in all size fractions.
Resilient materials normally present problem in obtaining accurate and uniform hole size and position. Tool is fabricated from stiff metal rod such as tungsten or carbon steel that has diameter slightly smaller than required hole. Piercing/centering point is ground on one end of rod. Rod is then plasma-sprayed (flame-sprayed) with suitable hard abrasive coating. High-speed, slow-feed operation of tool is necessary for accurate holes, and this can be done with drill press, hard drill, or similar machines.
Tool drills small hole perpendicular to and at bottom of blind hole. It consists of carbide cutter brazed to flexible shaft, inside thin metal tube with 90 degree bend. Wood dowel holds tube while motor turns shaft and drives cutter. It was developed for clearing plugged fuel orifices. Concept is adaptable to other hard-to-reach drilling situations.
With a depth resolution of about 0.5 cm, the stratigraphy of the approximately 3 m Apollo 17 deep drill core by measurement of the total FeO concentration is characterized along with the FMR surface exposure (maturity) index Is/FeO, the metallic iron concentration Fe-vsm, and the FMR linewidth delta-H. For stratigraphic characterization, the first two parameters are the most important. Most of the core is characterized by a FeO concentration of approximately 15.5 wt. %; there is a more mafic zone in the upper approximately 75 cm where the maximum FeO concentration is approximately 18.5 wt. %, and a more felsic zone between approximately 225 and 260 cm where the minimum FeO concentration is approximately 14.0%. As indicated by Is/FeO, most of the soil in the core is submature to mature; the only immature zone is located between approximately 20 and 60 cm and is one of the most distinctive features in the core. A two stage model for the depositional and evolutionary history of the Apollo 17 deep drill core is proposed: (1) deposition by one event approximately 110 m.y. ago or deposition by a sequence of closely spaced events initating a maximum of approximately 200 m.y. ago and terminating approximately 110 m.y. ago, (2) in situ reworking (gardening) to a depth of approximately 26 cm in the period between approximately 110 m.y. ago and the present day.
Lithologic abundances obtained from modal analyses of a continuous string of polished thin sections indicate that the Apollo 17 deep drill core can be divided into three main zones: An upper zone (0-19 cm depth) characterized by high abundances of agglutinates (30%) and a high ratio of mare to non-mare lithic fragments (less than 0.8); a coarse-grained layer (24-56 cm) rich in fragments of high-Ti mare basalts and mineral fragments derived from them, and poor in agglutinates (6%); and a lower zone (56-285 cm) characterized by variable but generally high agglutinate abundances (25%) and a low ratio of mare to nonmare lithic fragments (0.6). Using observations of the geology of the landing site, the principles of cratering dynamics, and the vast amount of data collected on the core, the following depositional history for the section of regolith sampled by the Apollo 17 drill core: was devised.