Patent Application
20120000097
The present invention relates to an adjustment mechanism for adjusting force vectors in excavating natural and man-made formations, including downhole drilling, trenching, mining, and road milling. More specifically, the present invention relates to adjusting a resultant force vector acting on a cutting element in an excavating assembly. The magnitude and direction of resultant force vector depends on a plurality of excavating parameters.
U.S. Pat. No. 6,116,819 to England, which is herein incorporated by reference for all that it contains, discloses a method of continuous flight auger piling and a continuous flight auger rig, wherein an auger is applied to the ground so as to undergo a first, penetration phase and a second, withdrawal phase, and wherein the rotational speed of and/or the rate of penetration of and/or the torque applied to the auger during the first, penetration phase are determined and controlled as a function of the ground conditions and the auger geometry by means of an electronic computer so as to tend to keep the auger flights loaded with soil originating from the region of the tip of the auger. During the withdrawal phase, concrete may be supplied to the tip of the auger by way of flow control and measuring means, the rate of withdrawal of the auger being controlled as a function of the flow rate of the concrete, or vice-versa, by means of an electronic computer so as to ensure that sufficient concrete is supplied to keep at least the tip of the auger immersed in concrete during withdrawal.
U.S. Pat. No. 5,358,059 to Ho, which is herein incorporated by reference for all that it contains, discloses an apparatus and method for use in determining drilling conditions in a borehole in the earth having a drill string, a drill bit connected to an end of the drill string, sensors positioned in a cross-section of the drill string axially spaced from the drill bit, and a processor interactive with the sensors so as to produce a humanly perceivable indication of a rotating and whirling motion of the drill string. The sensors serve to carry out kinematic measurements and force resultant measurements of the drill string. The sensors are a plurality of accelerometers positioned at the cross-section. The sensors can also include a plurality of orthogonally-oriented triplets of magnetometers. A second group of sensors is positioned in spaced relationship to the first group of sensors along the drill string. The second group of sensors is interactive with the first group of sensors so as to infer a tilting of an axis of the drill string.
U.S. Pat. No. 4,445,578 to Millheim, which is herein incorporated by reference for all that it contains, discloses an apparatus for measuring the side force on a drill bit during drilling operations and transmitted to the surface where it can be used in predicting trajectory of the hole and taking corrective action in the drilling operation. A downhole assembly using a downhole motor is modified to include means to detect the side thrust or force on a bit driven by the motor and the force on the deflection means of the downhole motor. These measured forces are transmitted to the surface of the earth during drilling operations and are used in evaluating and controlling drilling operations. Means are also provided to measure magnitude of the force on a downhole stabilizer.
In one aspect of the present invention, a method of excavation with pointed cutting elements, comprising the steps of providing a excavating assembly with at least one pointed cutting element, the pointed cutting element comprising a rounded apex that intersects a central axis, the pointed cutting element further has a characteristic of having its highest impact resistance to resultant forces aligned with the central axis; engaging the at least one pointed cutting element against a formation such that the formation applies a resultant force against the pointed cutting element; determining an angle of the resultant force; and modifying at least one excavating parameter to align the resultant force with the pointed cutting element's central axis.
The excavating assembly may comprise comprises at least one transducer. At least one force measured by the first and second transducer may be modified to align the resultant force with the pointed cutting element's central axis. At least one excavating parameter may be a torque force acting laterally on the cutting element. At least one excavating parameter may be weight loaded to each cutting element. The pointed cutting elements may comprise a wear resistant tip comprising a superhard material bonded to a cemented metal carbide.
The method of excavating may comprise the step of determining an ideal torque, ideal rotational velocity, and/or ideal weight available to drive the excavating assembly. The method may further comprise the step of increasing or decreasing weight loaded to each cutting element to align the resultant force with the central axis of the cutting element. The method may further comprise the step of increasing or decreasing rotational velocity to align the resultant force with the central axis of the cutting element.
The excavating assembly may be an auger assembly, a milling machine, a trenching machine, an excavator, or combinations thereof. A method of determining the angle of the resultant force may comprise a plurality of measurement mechanism positioned inside the cutting elements. A magnitude and direction of the weight loaded to each cutter, and torque acting on each cutter may be measured. The measured data may be transferred to an excavating control mechanism. The measurement mechanism may comprise a strain gauge mounted on a pre-tensioned strain bolt, a button load cell, or combination thereof. The measuring mechanism may be oriented in three different orthogonal directions. The excavating control mechanism may continuously modify the excavating parameters to align the resultant force with the pointed cutting element's central axis regardless of ground condition. In embodiments, where the excavating assembly, comprises a drill bit with blade, at least one blade may comprise a measuring mechanism positioned in its thickness.
a is a cross-sectional diagram of another embodiment of a pointed cutting element.
b is an orthogonal diagram of an embodiment of a cutter arrangement of an auger head assembly.
a is a perspective diagram of an embodiment of a drill bit.
b is a cross-sectional diagram of another embodiment of a pointed cutting element.
a is a perspective diagram of another embodiment of a drill bit.
b is a cross-sectional diagram of an embodiment of a blade of a drill bit.
The method of measuring the weight loaded to each cutting element 180 may comprise the step of measuring the torque applied to the rotating wheel 150 in the direction of rotation. The weight loaded to the cutting elements 180 may be calculated by using the formula:
Weight on bit(WOB)=(weight of the auger assembly 120)−(tangential force on the wheel 150×radius of the wheel 150)
The weight of the auger assembly 120 and the radius of the wheel 150 are fixed; thus, the changing the tangential force on the wheel is the primary mechanism for modifying WOB.
When the vector force does not align with the central axis of the cutting element, then the resultant vector forces do not either. Since the cutting element is pointed, the non-aligned forces may load the cutting element in a way that the cutting element in a direction that the cutting element is weak. For example, a pointed cutting element does not have a large cross section at its apex, so a load that transverses the apex meets little resistance from the apex's cross section. On the other hand, when the load is substantially aligned with the central axis of the cutter, the entire length of the cutting element may buttress the apex again the load.
The resultant force 360 may vary depending on a number of excavating parameters such as weight loaded to each cutting element, torque, rotational velocity, rate of penetration and type of formation.
The excavating parameters may be modified to substantially align the resultant force 360 with the pointed cutting element's central axis. The pointed cutting element 180 is believed to have the characteristic of having its highest impact resistance along its central axis. At least one excavating parameter may be modified to align the resultant force 360 with the pointed cutting element's central axis. The electronic means may continuously modify the excavating parameters to align the resultant force 360 with the pointed cutting element's central axis regardless of formation 300 conditions.
For purposes of this disclosure, an aligned resultant force is within + or − ten degrees of the axis in some embodiments. In other embodiments, substantially aligning may be within five degrees. Preferably, an aligned resultant force is within 2 degrees.
Referring to
Frequently, natural and man-made formations vary in hardness and composition. As the formation's characteristics vary, so may the resultant force angles and strengths. For example, as a drill bit transitions between a soft and a hard formation, the stresses on the cutting elements may change, resulting in a change in the excavating parameters to keep the resultant forces substantially aligned with the element's central axis.
Referring to
b discloses an orthogonal diagram of an embodiment of an auger head assembly 200 comprising a plurality of pointed cutting elements 180. At least one of the pointed cutting elements 180 may comprise measuring mechanism such as strain gauges 600 as shown in
a discloses a plurality of pointed cutting elements 180 in a drill bit 1100 that incorporate the present invention. At least one cutting element 180 may comprise at least one measuring means such as strain gauges 600 positioned inside its body as illustrated in
a discloses a plurality of blades 1200 in a drill bit 1100. Each blade 1200 may comprise a plurality of pointed cutting elements 180. At least one blade 1200 may comprise at least one measuring means such as strain gauges 600 positioned in its cross-section. In some embodiments, the strain gauges 600 may be positioned in three different axes of rotation as illustrated in
In some cases, the resultant force may be too vertical or too horizontal or too offset from the cutting element's central axis. In such cases, the resultant force may be aligned with the cutting element's central axis by modifying at least one excavating parameter as explained in the previous paragraphs. In some cases, a trajectory angle of the cutting element may be too steep, thereby creating too low backstage offset clearance. Thus, sides of the forward end of the cutting element may come in contact with the formation, thereby eroding the sides of the cutting element. In such cases, the weight loaded to each cutting element may be increased to create sufficient backstage offset clearance. The backstage offset clearance may also depend on rate of penetration of the drilling assembly. In some embodiments, the rate of penetration may be decreased to create sufficient backstage offset clearance.
Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.
