A machining process method for a cone of a tri-cone bit

Abstract

This application discloses a machining process for a tri-cone drill bit. The process involves rough turning the inner bore and outer conical surface of the tri-cone, followed by carburizing and high-temperature tempering. After high-temperature tempering, the inner bore and outer conical surface are finish-turned, and the finish-turned tri-cone is then quenched and low-temperature tempered. Multiple tooth holes are drilled and reamed on the surface of the low-temperature tempered tri-cone. The surface of the tri-cone has multiple tooth rings, with the tooth holes evenly distributed along the circumference of the tooth rings. During tooth fixing, the tooth holes on each tooth ring are first fixed at intervals, followed by supplementary tempering. Then, the remaining tooth holes on each tooth ring are fixed. This two-stage tooth fixing process, with supplementary tempering between the two fixing operations, eliminates stress during the fixing process and prevents early cracking of the tri-cone. The interval fixing increases the spacing between adjacent teeth during supplementary tempering, improving the fixation strength and preventing the fixed alloy teeth from falling off.

Description

Technical Field

[0001] This application belongs to the field of machining technology, specifically relating to a machining process for a tricone drill bit. Background Technology

[0002] Tricone drill bits are widely used in drilling operations in various open-pit mines such as iron ore, copper ore, and coal ore. A tricone drill bit consists of three jaws and their journals, assembled with three mating cones via a bearing system. The threads at the tail of the jaws connect to the drill rod of the drilling rig. Carbide teeth are embedded in the cones for directly breaking rock. The cones rotate around the jaw journal using the bearing system, and the drilling pressure from the drilling rig is transmitted to the cone teeth through the journal bearings and acts on the rock mass.

[0003] Because the alloy teeth fixed into the roller cone are very dense, and the alloy teeth are fixed into the roller cone with a certain interference fit, if the stress generated by the fixed alloy teeth is not effectively released, it will cause cracks in the roller cone.

[0004] The existing machining process for roller cones is as follows: rough turning of the inner hole and outer conical surface of the roller cone → integral carburizing and high-temperature tempering → finish turning of the inner hole and outer conical surface of the roller cone → integral quenching and low-temperature tempering → drilling and reaming of the tooth hole → tooth fixing. However, this process cannot release the stress generated by fixing the alloy teeth, which can lead to cracks, premature cracking of the roller cone body or premature detachment of the fixed alloy teeth, affecting the alloy teeth's ability to break rocks and thus affecting the service life of the triode drill bit. Summary of the Invention

[0005] To address the technical problem that current rotary cone machining processes cannot release the stress generated by the embedded alloy teeth, resulting in cracks, premature cracking of the rotary cone body, or premature detachment of the embedded alloy teeth, thus affecting the service life of tricone drill bits, this application provides a rotary cone machining process method for tricone drill bits.

[0006] This application provides a method for machining the roller cones of a tricone drill bit, including:

[0007] The inner bore and outer conical surface of the roller are rough-machined, and the roller after rough machining is carburized and tempered at high temperature.

[0008] After high-temperature tempering, the inner hole and outer conical surface of the roller cone are precision machined. The precision-machined roller cone is then quenched and tempered at low temperature.

[0009] Multiple toothed holes are drilled and reamed on the surface of the roller cone after low-temperature tempering. The surface of the roller cone is provided with multiple toothed rings, and several of the toothed holes are evenly distributed along the circumference of the toothed rings.

[0010] The teeth on each gear ring are fixed at intervals through several of the aforementioned tooth holes;

[0011] Additional tempering of the toothed gears after interlocking;

[0012] The remaining tooth holes on each gear ring are then fixed.

[0013] In some embodiments, fixing a plurality of the tooth holes on each gear ring at intervals includes fixing half of the number of tooth holes on each gear ring, with a gap of one tooth hole between two adjacent fixed tooth holes.

[0014] In some embodiments, five toothed rings are provided, which are, from top to bottom, a first toothed ring, a second toothed ring, a third toothed ring, a fourth toothed ring, and a fifth toothed ring. The first toothed ring has four tooth holes, the second toothed ring has eight tooth holes, the third toothed ring has twelve tooth holes, the fourth toothed ring has sixteen tooth holes, and the fifth toothed ring has twenty tooth holes.

[0015] In some embodiments, fixing half of the tooth holes on each gear ring includes: fixing two tooth holes on the first gear ring located at a 180-degree angle; fixing four tooth holes on the second gear ring, with adjacent fixed tooth holes spaced 90 degrees apart; fixing six tooth holes on the third gear ring, with adjacent fixed tooth holes spaced 60 degrees apart; fixing eight tooth holes on the fourth gear ring, with adjacent fixed tooth holes spaced 45 degrees apart; and fixing ten tooth holes on the fifth gear ring, with adjacent fixed tooth holes spaced 36 degrees apart.

[0016] In some embodiments, the additional tempering of the toothed roller after the interlocking teeth are fixed includes: placing the toothed roller after the interlocking teeth are fixed in a tempering furnace, heating it to 170-190°C, holding it at that temperature for 3-4 hours, and then air-cooling it to room temperature.

[0017] In some embodiments, the carburizing treatment includes:

[0018] a. Place the roller cone in a carburizing furnace and carry out carburizing in a carburizing atmosphere with a carbon potential of 0.6%-1.25% and a temperature of 825-830℃.

[0019] b. The roller cone treated in step a is subjected to diffusion treatment in a carburizing atmosphere with a carbon potential of 1.0%-1.25% and a temperature of 825-830℃.

[0020] In some embodiments, the high-temperature tempering includes: cooling the roller cone treated in step b to 850-870°C in a carburizing furnace, holding it at that temperature for 30 minutes, and then air-cooling or oil-cooling it to room temperature.

[0021] In some embodiments, the quenching process includes: placing the precision-machined gear in a quenching furnace, heating it to 850°C, holding it at that temperature for 2 hours, and then removing it from the furnace and oil-cooling it to room temperature.

[0022] In some embodiments, the low-temperature tempering includes: placing the quenched gear in a tempering furnace, heating it to 220-230°C, holding it at that temperature for 2 hours, and then air-cooling it to room temperature.

[0023] In some embodiments, the roller is made of 20CrNiMo material.

[0024] A machining process for a tricone drill bit according to one or more embodiments of this application has the following advantages compared to the prior art:

[0025] During tooth fixing, several tooth holes on each tooth ring are first fixed at intervals. The tooth cones after the interval fixing are then subjected to supplementary tempering. Then, the remaining tooth holes on each tooth ring are fixed. Fixing the teeth in two stages with supplementary tempering between the two fixing stages can eliminate stress during the fixing process and prevent premature cracking of the tooth cones. Interval fixing can increase the spacing between two adjacent teeth during supplementary tempering, which can improve the firmness of the fixing and prevent the fixed alloy teeth from falling off, thereby increasing the service life of the tricone drill bit. Attached Figure Description

[0026] Figure 1 A schematic flowchart of the machining process for a tricone drill bit in an embodiment of this application is shown.

[0027] Figure 2 A schematic diagram of the supplementary tempering process is shown for the machining process of the tri-cone drill bit in the embodiments of this application.

[0028] Figure 3 The diagram illustrates the carburizing and high-temperature tempering process of the tri-cone drill bit machining method in the embodiments of this application.

[0029] Figure 4 A schematic diagram of the quenching process of the tri-cone drill bit machining method in an embodiment of this application is shown.

[0030] Figure 5 A schematic diagram of the low-temperature tempering process of the tricone drill bit machining process in the embodiments of this application is shown.

[0031] Figure 6 This illustration shows a schematic diagram of the toothed gear structure after intermittent tooth fixing in the toothed gear machining process of the three-cone drill bit in an embodiment of this application.

[0032] Figure 7 This diagram illustrates the distribution of alloy teeth on the rollers after intermittent tooth fixing in the roller machining process of the tri-cone drill bit in an embodiment of this application.

[0033] Figure 8This illustration shows a schematic diagram of the gear structure after all teeth are fixed in the gear machining process of the tri-cone drill bit in an embodiment of this application.

[0034] Explanation of reference numerals in the attached diagram: 100 - toothed hole; 1 - first toothed ring; 2 - second toothed ring; 3 - third toothed ring; 4 - fourth toothed ring; 5 - fifth toothed ring. Detailed Implementation

[0035] To enable those skilled in the art to more clearly understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0036] Please see Figures 1-8 This application provides a method for machining the roller cones of a tricone drill bit, comprising:

[0037] Step S1: Roughly turn the inner hole and outer conical surface of the roller cone, and then perform carburizing and high-temperature tempering on the rough-turned roller cone;

[0038] Step S2: After high-temperature tempering, the inner hole and outer conical surface of the roller cone are precision machined, and the precision-machined roller cone is then quenched and tempered at low temperature.

[0039] Step S3: Drill and ream multiple tooth holes 100 on the surface of the roller cone after low-temperature tempering. The surface of the roller cone is provided with multiple tooth rings, and several of the tooth holes 100 are evenly distributed along the circumference of the tooth rings.

[0040] Step S4: Spacingly fix the teeth in the plurality of tooth holes 100 on each tooth ring;

[0041] Step S5: Perform additional tempering on the toothed gears after interlocking;

[0042] Step S6: Fix the remaining tooth holes 100 on each tooth ring.

[0043] In this embodiment, the roller cone is made of 20CrNiMo. 20CrNiMo is a grade of alloy structural steel specified in Chinese national standards, with the unified numerical code A50202. Because it contains molybdenum, 20CrNiMo not only has excellent comprehensive properties but also withstands certain temperatures, making it suitable for manufacturing gears, rotors, connecting rods, valve sections, and forgings for steam turbines and internal combustion engines. 20CrNiMo round steel has high hardenability, no temper brittleness, excellent weldability, a very low tendency to form cold cracks, and good machinability and cold strain plasticity. 20CrNiMo is generally used in the quenched and tempered or carburized and quenched state.

[0044] The tri-cone drill bit machining process method provided in this application embodiment involves first fixing a plurality of the tooth holes 100 on each tooth ring at intervals during tooth fixing, then performing supplementary tempering on the toothed cone after interval tooth fixing, and then fixing the remaining tooth holes 100 on each tooth ring. This two-stage tooth fixing process, with supplementary tempering between the two fixings, eliminates stress during the tooth fixing process and prevents early cracking of the toothed cone. The interval tooth fixing increases the spacing between adjacent teeth during supplementary tempering, improving the firmness of the tooth fixing and preventing the fixed alloy teeth from falling off, thereby increasing the service life of the tri-cone drill bit.

[0045] In some embodiments, fixing a plurality of the toothed holes 100 on each gear ring at intervals includes fixing half of the toothed holes 100 on each gear ring, with a gap of one toothed hole 100 between two adjacent toothed holes 100 being fixed. By spacing one toothed hole 100 between two adjacent toothed holes 100 being fixed, the distance between two adjacent teeth during supplementary tempering is increased, which can improve the firmness of the fixing and prevent the fixed alloy teeth from falling off.

[0046] In some further embodiments, five toothed rings are provided, which are, from top to bottom, a first toothed ring 1, a second toothed ring 2, a third toothed ring 3, a fourth toothed ring 4, and a fifth toothed ring 5. The first toothed ring 1 has four toothed holes 100, the second toothed ring 2 has eight toothed holes 100, the third toothed ring 3 has twelve toothed holes 100, the fourth toothed ring 4 has sixteen toothed holes 100, and the fifth toothed ring 5 has twenty toothed holes 100.

[0047] In some further embodiments, fixing half of the tooth holes 100 on each gear ring includes: fixing two tooth holes 100 on the first gear ring 1 located at a 180-degree angle; fixing four tooth holes 100 on the second gear ring 2, with adjacent fixed tooth holes 100 spaced 90 degrees apart; fixing six tooth holes 100 on the third gear ring 3, with adjacent fixed tooth holes 100 spaced 60 degrees apart; fixing eight tooth holes 100 on the fourth gear ring 4, with adjacent fixed tooth holes 100 spaced 45 degrees apart; and fixing ten tooth holes 100 on the fifth gear ring 5, with adjacent fixed tooth holes 100 spaced 36 degrees apart.

[0048] In some embodiments, supplementary tempering of the toothed triodes after interlocking includes: placing the toothed triodes in a tempering furnace, heating them to 170-190°C, holding them at that temperature for 3-4 hours, and then air-cooling them to room temperature. Supplementary tempering can eliminate stress during the tooth-fixing process, prevent premature cracking of the triodes, and thus improve the service life of the triode drill bit.

[0049] In some embodiments, the carburizing treatment includes:

[0050] a. Place the roller cone in a carburizing furnace and carry out carburizing in a carburizing atmosphere with a carbon potential of 0.6%-1.25% and a temperature of 825-830℃.

[0051] b. The roller cone treated in step a is subjected to diffusion treatment in a carburizing atmosphere with a carbon potential of 1.0%-1.25% and a temperature of 825-830℃.

[0052] In the carburizing process, the carbon potential in step a is preferably 1.25%, and the carbon potential in step b is most preferably 1.0%. In the carburizing process, step a is a strong carburizing process, in which the carbon potential is the highest. At this time, carbon atoms can diffuse fully to the surface of the workpiece, increasing the depth of the carburized layer. In step b, the carbon potential gradually decreases, which can increase the concentration of carbides on the outermost surface, thereby improving the surface hardness and further improving the wear resistance.

[0053] In some embodiments, the high-temperature tempering includes: cooling the roller cone treated in step b to 850-870°C in a carburizing furnace, holding at that temperature for 30 minutes, and then air-cooling or oil-cooling to room temperature. High-temperature tempering of the roller cone after carburizing can improve the toughness of the roller cone core. The preferred high-temperature tempering temperature is 860°C.

[0054] In some embodiments, after high-temperature tempering, the microstructure of the toothed claw surface still exhibits defects such as excessive retained austenite, abundant and network-like carbides, and coarse grains, resulting in insufficient mechanical strength. Therefore, it is necessary to quench the precision-machined toothed claw. The quenching process includes: placing the precision-machined toothed claw in a quenching furnace, heating it to 850°C, holding it at that temperature for 2 hours, and then oil-cooling it to room temperature. The quenching process improves the microstructure and mechanical properties of the toothed claw surface.

[0055] In some embodiments, the low-temperature tempering includes: placing the quenched gear in a tempering furnace, heating it to 220-230°C, holding it at that temperature for 2 hours, and then air-cooling it to room temperature. The preferred tempering temperature is 230°C.

[0056] In the above carburizing process, the carburizing process is carried out in a carburizing furnace, and the atmosphere of the carburizing furnace can be adjusted as needed. The present invention does not impose any particular restrictions on the carbon source atmosphere; propane, methanol, acetone, etc., which are well-known to those skilled in the art, can be used, as long as they meet the carbon potential requirements of the present invention. The use of a carbon source atmosphere is also common knowledge to those skilled in the art.

[0057] In the above-mentioned carburizing treatment, high-temperature tempering, quenching treatment, low-temperature tempering and supplementary tempering, those skilled in the art can select and determine the holding time according to the size of the workpiece and the amount of furnace loading, which is a conventional technical means for those skilled in the art.

[0058] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0059] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0060] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0061] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0062] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for machining the roller cones of a tricone drill bit, characterized in that, include: The inner bore and outer conical surface of the roller are rough-machined, and the roller after rough machining is carburized and tempered at high temperature. After high-temperature tempering, the inner hole and outer conical surface of the roller cone are precision machined. The precision-machined roller cone is then quenched and tempered at low temperature. Multiple toothed holes are drilled and reamed on the surface of the roller cone after low-temperature tempering. The surface of the roller cone is provided with multiple toothed rings, and several of the toothed holes are evenly distributed along the circumference of the toothed rings. The teeth on each gear ring are fixed at intervals through several of the aforementioned tooth holes; Additional tempering of the toothed gears after interlocking; The remaining tooth holes on each gear ring are then fixed. The carburizing treatment includes: a. Place the roller cone in a carburizing furnace and carry out carburizing in a carburizing atmosphere with a carbon potential of 0.6%-1.25% and a temperature of 825-830℃. b. The roller cone treated in step a is subjected to diffusion treatment in a carburizing atmosphere with a carbon potential of 1.0%-1.25% and a temperature of 825-830℃.

2. The machining process for a tricone drill bit according to claim 1, characterized in that, The method of fixing the teeth at intervals on a plurality of teeth on each gear ring includes fixing half of the number of teeth on each gear ring, with a gap of one tooth hole between two adjacent teeth that are fixed.

3. The machining process for a tricone drill bit according to claim 2, characterized in that, The gear rings are provided in five parts, and from top to bottom they are the first gear ring, the second gear ring, the third gear ring, the fourth gear ring and the fifth gear ring. The first gear ring has four tooth holes, the second gear ring has eight tooth holes, the third gear ring has twelve tooth holes, the fourth gear ring has sixteen tooth holes and the fifth gear ring has twenty tooth holes.

4. The machining process for a tricone drill bit according to claim 3, characterized in that, The process of fixing half of the tooth holes on each gear ring includes: fixing two tooth holes on the first gear ring located at a 180-degree angle; fixing four tooth holes on the second gear ring, with a 90-degree interval between adjacent fixed tooth holes; fixing six tooth holes on the third gear ring, with a 60-degree interval between adjacent fixed tooth holes; fixing eight tooth holes on the fourth gear ring, with a 45-degree interval between adjacent fixed tooth holes; and fixing ten tooth holes on the fifth gear ring, with a 36-degree interval between adjacent fixed tooth holes.

5. The machining process for a tricone drill bit according to claim 1, characterized in that, The additional tempering of the toothed roller after interlocking includes: placing the toothed roller in a tempering furnace, heating it to 170-190℃, holding it at that temperature for 3-4 hours, and then air-cooling it to room temperature.

6. The machining process for a tricone drill bit according to claim 1, characterized in that, The high-temperature tempering includes: cooling the roller cone treated in step b to 850-870°C in a carburizing furnace, holding it at that temperature for 30 minutes, and then air-cooling or oil-cooling it to room temperature.

7. The machining process for a tricone drill bit according to claim 1, characterized in that, The quenching process includes: placing the precision-machined gear in a quenching furnace, heating it to 850°C, holding it at that temperature for 2 hours, and then removing it from the furnace and oil-cooling it to room temperature.

8. The machining process for a tricone drill bit according to claim 7, characterized in that, The low-temperature tempering includes: placing the quenched gear in a tempering furnace, heating it to 220-230℃, holding it at that temperature for 2 hours, and then air-cooling it to room temperature.

9. The machining process for a tricone drill bit according to any one of claims 1-8, characterized in that, The roller cone is made of 20CrNiMo material.

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