The author's abstract of the final work of the Master on the subject:
"Research and improvement of the focusing systems with the ball signalling element"
Introduction
Orientator devices and ways, which are used in coremetry, can be classified as assigned for the direct, indirect and combined orientation.
The first ones serve for definition of the spatial position of the label put on a core concerning a direction on the magnetic or geographical pole, and also any direction which position is known in relation to the direction to the pole.
The second group of devices serves for definition of the angular position of the label concerning the apsidal plane in the inclined chinks. In addition it is required the data of inclinometry for definition of position of the label and structural elements in the space.
The third group includes devices which have gauges of apsidal plane, azimuth and the corner of inclination of the chink.
The magnetic compass as a focusing device may be built-in in the corescope or independent, being lowered to corescope at the moment of orientation through a column of pipes.
Importance
The importance of the given subject is on a low level recently because of insufficient financing all prospecting branch.
Orientator devices with the ball signalling element have been developed and are applied for a long time, however there is always an opportunity to improve the characteristic of the device. By development of the new device it is necessary to aspire to increasing accuracy of orientation especially at position of a chink which is close to vertical, to reduction of expenses for manufacturing and service, and also to reliability of the device.
Goals and Objects which are solved in the final work of the Master
The main goal of the final work of the Master is definition of sensitivity of the ball signalling element depending on the diameter of the ball, the form and quality of processing of the trench, the corner of inclination of the mobile part of the stand to horizontal, and a kind of the working suuroundings of the ball – trench system.
Manufacturing three experimental cups with trenches of the different form and quality of processing, and also the experimental stand is provided during the final work of Master fulfilment.
It will be offered the recommendation for designing focusing systems with the ball signalling element after realization of experiment and processing of results.
The simplified scheme of the experimental stand is shown in the animated form:
Grey- a ball.
Red- a sliding scale.
Green - the wooden basis.
Dark blue - a mobile part of the stand.
Brown - an experimental cup.
Accuracy of orientation is the statistical characteristic of a possible error of individual definition of parameters of spatial position of a core in a chink up to tearing it off from face. It is adjusted differently in orientator devices of various types.
The ring ball plumb. Accuracy of registration by the ball of position of apsidal plane depends on a ratio of rolling making gravity Т and forces of resistance of rest. The more is inclination of a trench (the more is antiaircraft corner of a chink), the more is rolling force Т. The forces of resistance consisting of force of swaying friction, the static pressure of shift, the dynamic resistance to movement of the ball, may be basically determined for some given idealized conditions. In turns it demands the account of radiuses of the ball and the circle of the trench.
The ball is fixed in balance at equality of the moment of rolling force to the sum of the moments of forces of resistance if not to take into account casual dynamic influences.
There are the settlement formulas, allowing to take into account, viscosity of environment, a roughness of a trench, contact pressure of a ball upon a trench, and also formulas for calculation of necessary diameter of a ball in view of all listed factors. These formulas are fair and allow to understand structure, mutual relation and a role of the separate factors determining accuracy of orientation. However it would be wrong to consider these formulas as an element and a method of the technological analysis and designing. Formulas contain set of factors which are not always possible for defining. A deviation of a ball is result of cumulative influence of huge set of factors, ones of which are unknown (presence of vibrations of the acoustic frequency formed by a stream washing liquid), others are hardly definable (action of the reagent added in washing solution) or have casual character. But each of factors may have as much as big influence on accuracy of orientation. It is incorrect to represent the process as determined in the technological attitude. The system analysis offers other approach.
We shall choose diameter of a ball as adjustable key parameter of a key detail since the mechanical, geological and physical factors finally realize their properties through it. We shall take a roughness of a trench and structure of environment as the key conditions determining final action of set of factors. And we shall allocate the extreme values applied in practice for diameter of a ball (6 mm and 12 mm), roughnesses of a trench (turning fair processing and grinding of surface) and environments (air, water and clay solution). The specified limiting parameters of key characteristics reflect practically significant limits of change of conditions and practically real characteristics of accuracy.
Results of several thousand laboratory experiences are submitted in the diagram (fig. 6) which allow to estimate limits of accuracy of orientation S for various conditions at various corners of inclination of chink n.
Fig. 6. Diagrams of dependence of an error of the registrar apsidal directions from a corner of inclination of an axis of a trench of the registrar for various conditions: 1 - water environment; 2 - clay solution; 3 - air; 4 - the ball in diameter of 5 mm; 5 - the ball of 6 mm.
Error of definition of position apsidal plane of a chink by inclinometer 6£ is consequence of a tool mistake of the latter and positions which it occupies concerning axes of a trunk in a point of measurement. The admitted error of measurement of an azimuth of apsidal plane of a chink by existing inclinometers is equal ±5 ° at zenith corners 5° and more.
The accuracy of definition of position apsidal plane is reduced in inverse proportion to their sine in process of reduction of the zenithal corners 0.
The inclinometer tool error is defined by size of stagnation of the magnetic needle or the drift of a gyroscope considered earlier. It is recommended to make measurement of curvature at rise of the device in avoidance uncoaxialness of inclinometer and chink.
Stagnation of the sensitive element executed as ball freely going for a drive in a trench, a pendulum (framework) which axis of rotation coincides with a geometrical axis of the device.
The sum of the external moments is defined by force of friction of a ball in a trench. Force of swaying friction of a ball in a trench depends on a structure of the latter. Three types of structures are applied in practice: rectangular, triangular and semicircular.
The rectangular structure of a trench is a special case of the triangular one. The forces of friction appear which are consequence of two makings q1 q2 of weights of a ball under inclination of the device (chink) having a rectangular or triangular structure of a trench.
The character of change of force of swaying friction of a ball in a trench is various under inclination of the latter in the specified structures.
Conclusions
Analyzing character of change of force of friction, it is possible to draw a conclusion that the rectangular structure of a trench in comparison with triangular is more rational. The reason is that force of swaying friction with reduction of an zenith corner aspires to zero, that rather essentially influences accuracy of orientation.
The greatest attention is deserved with a structure of the round form. In this case force of weight of a ball is directed normally to making of a trench at any zenith corner, and, hence, force of friction is minimal, not dependent on the zenith corner of the device.
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