A PDC single-tooth cutting rock-breaking experimental device and a method for analyzing the rock-breaking mechanism.

Abstract

This invention provides a PDC single-tooth rock-breaking experimental device and a method for analyzing the rock-breaking mechanism. The experimental device includes a rock-breaking device body, a PDC tooth cutting depth adjustment mechanism, a cutting speed adjustment mechanism, and a cutting force measurement mechanism. The cutting speed adjustment mechanism can adjust the cutting speed of the rock sample; the rock-breaking device body is used to fix and install the cutting depth adjustment mechanism; the cutting depth adjustment mechanism can clamp the PDC tooth and precisely control its inclination angle and cutting depth; the cutting force measurement mechanism can monitor the cutting force on the rock sample. The method includes the following steps: setting parameters such as cutting depth, cutting speed, and inclination angle; monitoring the cutting force and recording the dynamic rock crushing process; sieving and collecting rock fragments, determining the mass fraction of different groups of rock fragments, and preliminarily determining the ductile-brittle crushing mode of the rock based on the distribution pattern of the rock fragments. This invention has the advantages of precisely controlling the cutting depth, PDC tooth inclination angle, and cutting speed.

Description

Technical Field

[0001] This invention relates to the field of drilling equipment technology, specifically to a PDC single-tooth cutting rock-breaking experimental device and a method for analyzing the rock-breaking mechanism. Background Technology

[0002] Since its invention in 1973, the PDC drill bit has been widely used in the oil and gas drilling industry due to its advantages such as high rock-breaking efficiency, long service life, and good stability. In 2004, the application volume of PDC drill bits surpassed that of roller cone drill bits for the first time, and its total footage now accounts for more than 90% of the global oil and gas industry. Exploring the interaction between PDC drill bits and rocks, and clarifying the rock breaking mechanism under different parameters, can provide a theoretical basis for the structural design of PDC drill bits and the optimization of drilling parameters. However, due to the complexity of downhole conditions, the diverse movement modes of PDC drill bits, and the strong mutual interference between teeth, directly exploring the rock-breaking mechanism of PDC drill bits is somewhat difficult. As the basic unit of the drill bit, the PDC tooth is relatively less affected by factors, and the rock-breaking process is relatively simple. Therefore, many scholars have conducted experimental research on single-tooth cutting rock breaking of PDC drill bits to explore the influence of key parameters on the rock-breaking behavior of PDC teeth, providing theoretical guidance for the structural design of high-efficiency rock-breaking drill bits.

[0003] Numerous studies have shown that the rock-breaking characteristics of PDC (Potentially Dip-Chip) teeth are primarily influenced by the back rake angle and cutting depth. As the cutting depth increases, the rock fracture mode gradually shifts from plastic to brittle fracture, and the generated rock cuttings change from powdery to blocky, resulting in a rapid decrease in the specific energy of rock breaking. Simultaneously, with increasing cutting depth, PDC teeth gradually transition from abrasive wear to impact wear, leading to significant differences in the failure mode and rock-breaking mechanism of PDC drill bits. Changes in the back rake angle primarily affect the aggressiveness and wear resistance of the PDC teeth. Field applications indicate that a small back rake angle is suitable for drilling in soft formations, while the back rake angle should increase proportionally with increasing drilling depth and formation hardness. Selecting an appropriate back rake angle at different locations on the drill bit, based on formation conditions, is crucial for balancing the drill bit's rock-breaking performance and service life.

[0004] In single-tooth rock breaking experiments, cutting force is the most direct parameter reflecting the rock fragmentation characteristics. Its average value indicates the ease of rock fragmentation, and combined with the rock fragmentation volume, the specific energy of single-tooth rock breaking can be calculated to evaluate the rock fragmentation efficiency. Fluctuations in cutting force reflect the interaction between the PDC tooth and the rock. Therefore, accurate monitoring of the cutting force is crucial for the analysis of experimental results. At the same time, cutting force can only reflect the macroscopic fragmentation characteristics of rock under different experimental conditions to a certain extent; it needs to be combined with other experimental methods and parameters to further reveal the rock breaking mechanism of the PDC tooth.

[0005] Based on this, this invention proposes a PDC single-tooth rock-breaking experimental device. During the experiment, this device can precisely control parameters such as cutting depth, PDC tooth back rake angle, and cutting speed, and accurately monitor the variation of parameters such as cutting force. Furthermore, a standard experimental procedure based on this device is proposed to analyze the rock-breaking characteristics of single-tooth cutting under different parameters and reveal the corresponding rock fragmentation mechanism. Summary of the Invention

[0006] The purpose of this invention is to address at least one of the aforementioned shortcomings of the existing technology. For example, one objective of this invention is to provide a PDC single-tooth cutting rock-breaking experimental device that can precisely control parameters such as cutting depth, PDC tooth rake angle, and cutting speed, and accurately monitor the variation law of parameters such as cutting force. Another objective of this invention is to provide a PDC single-tooth cutting rock-breaking mechanism analysis method for analyzing the rock-breaking characteristics of single-tooth cutting under different parameters and revealing the corresponding rock fragmentation mechanism.

[0007] To achieve the above objectives, one aspect of the present invention provides a PDC single-tooth rock-breaking experimental device, the experimental device comprising a rock-breaking device body, a PDC tooth cutting depth adjustment mechanism, a cutting speed adjustment mechanism, and a cutting force measuring mechanism, wherein...

[0008] The cutting speed adjustment mechanism includes a housing, a control motor, a slide rail, a base, and a rock clamping mechanism, wherein...

[0009] The housing is horizontally arranged on a plane, and the slide rail is arranged on the upper end face of the housing along the length direction of the housing.

[0010] The base is movable on the slide rail, and the rock clamping mechanism is able to clamp the rock sample and fix it on the base.

[0011] The control motor is mounted on the housing and can drive the base and rock clamping mechanism to move axially along the slide rail at a predetermined speed to control the cutting speed of the rock sample.

[0012] The cutting and rock-breaking device body is horizontally positioned above the shell, and the cutting and rock-breaking device body is used to fix and install the PDC tooth cutting depth adjustment mechanism.

[0013] The PDC tooth cutting depth adjustment mechanism can clamp the PDC cutting tooth and adjust its inclination angle and cutting depth.

[0014] The cutting force measuring mechanism is mounted on the base and located on the side of the rock sample away from the PDC cutting teeth. The cutting force measuring mechanism is capable of monitoring the magnitude of the cutting force applied to the rock sample.

[0015] In one exemplary embodiment of one aspect of the present invention, the experimental apparatus may further include a support plate, which is fixedly disposed on the left and right sides of the housing and disposed opposite to each other, and the cutting and rock-breaking device body is horizontally disposed on the top of the support plate.

[0016] In one exemplary embodiment of this invention, the PDC tooth cutting depth adjustment mechanism includes a micrometer, a metal pressure plate, a spring, a connecting bolt, and a PDC tooth clamping mechanism, wherein...

[0017] The cutting and rock-breaking device body is also provided with an installation groove, the metal pressure plate is horizontally set and located above the installation groove, and the metal pressure plate is provided with screw holes;

[0018] The PDC tooth clamping mechanism is vertically arranged in the mounting slot;

[0019] The connecting bolt is disposed in the bolt hole and is fixedly connected to the upper end of the PDC tooth clamping mechanism;

[0020] The micrometer is set vertically and its lower end is fixedly connected to the upper end of the connecting bolt.

[0021] One end of the spring is connected to a metal pressure plate, and the other end is connected to the body of the rock-cutting device. In an exemplary embodiment of one aspect of the present invention, the PDC tooth clamping mechanism may include a PDC tooth clamping unit, a fastening bolt, a self-locking pad, a fixing bolt, and a metal pressure head, wherein...

[0022] The PDC tooth clamping unit has an upper inclined surface and a lower inclined surface on its left side. The self-locking pad has an inclined surface that mates with the upper inclined surface. The fastening bolt passes through the side wall of the mounting groove to fix the self-locking pad to the cutting and rock-breaking device body. The fixing bolt fixes the metal pressure head to the PDC tooth clamping unit. The metal pressure head is used to fix the PDC cutting teeth to the PDC tooth clamping unit.

[0023] In one exemplary embodiment of one aspect of the present invention, the micrometer may include an adjustment knob, a micrometer body, and a telescopic structure, wherein,

[0024] The micrometer body is fixedly mounted on the rock-breaking cutting device body. The upper end of the telescopic structure passes through the rock-breaking cutting device body and is connected to the micrometer body, while the lower end is fixedly connected to the upper end of the connecting bolt.

[0025] The adjustment knob is located on the micrometer body to adjust the telescopic length of the telescopic structure.

[0026] In one exemplary embodiment of this invention, the inclination angle of the PDC cutting teeth can be 0 to 75°, the cutting speed can be 1.6 to 230 mm / s, and the cutting depth control accuracy can reach 0.001 mm.

[0027] In one exemplary embodiment of one aspect of the present invention, the experimental apparatus may further include a PDC tooth tilt angle adjustment mechanism, which is disposed on the body of the rock-breaking cutting device, and a PDC tooth cutting depth adjustment mechanism is disposed on the PDC tooth tilt angle adjustment mechanism, which can achieve a tilt angle adjustment of 0 to 15°.

[0028] In one exemplary embodiment of this invention, the PDC tooth back tilt angle adjustment mechanism may include a rotary handle, a rotary screw, a locking nut, and an adjusting member. The cutting and rock-breaking device body is provided with a first opening and a fixed shaft. The adjusting member is provided with a second opening and an adjusting hole. The rotary screw is vertically disposed in the first opening. The locking nut is sleeved on the rotary screw and located below the cutting and rock-breaking device body. The rotary handle is sleeved on the rotary screw and located above the cutting and rock-breaking device body. The lower end of the rotary screw is provided with an adjusting head, which can move within the adjusting hole to rotate the adjusting member relative to the fixed shaft.

[0029] In one exemplary embodiment of one aspect of the present invention, the cutting force measuring mechanism may include a metal plate and a plurality of force sensors disposed on the metal plate, wherein the metal plate is disposed parallel to the side of the rock clamping mechanism.

[0030] Another aspect of the present invention provides a method for analyzing the rock-breaking mechanism of PDC single-tooth cutting, the method comprising the following steps:

[0031] Before starting the experiment, set the cutting depth, cutting speed, and rake angle;

[0032] During the experiment, the fluctuation pattern of cutting force was monitored, and a high-speed camera was used to record the dynamic rock crushing process in real time.

[0033] After the experiment, the collected rock fragments were sieved using sieves of different mesh sizes. The mass of different groups of rock fragments was determined and their mass fraction was calculated. Based on the distribution pattern of the rock fragments, the plastic-brittle fracture mode of the rock was preliminarily determined.

[0034] In another exemplary embodiment of the present invention, the method may further include:

[0035] The coordinate values ​​at different locations on the cutting groove surface are determined, the rock crushing volume is calculated, and the rock crushing specific energy is determined by combining the average cutting force. At the same time, the surface roughness of the cutting groove is calculated to further determine the rock ductile-brittle crushing mode.

[0036] In another exemplary embodiment of the present invention, the method may further include:

[0037] After the three-dimensional morphology analysis of the rock is completed, core samples are taken from the center of the cutting groove to observe the distribution characteristics of microcracks on the rock core surface and determine the micro-damage characteristics of the rock during the PDC tooth breaking process.

[0038] Meanwhile, rock samples were cut and thoroughly polished at different locations along the cutting groove to create thin cast sections. The distribution pattern of microcracks at the bottom of the cutting groove was observed to determine the internal damage characteristics of the rock during the PDC tooth breaking process.

[0039] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0040] (1) The cutting depth of the PDC cutting teeth can be precisely adjusted by the control of the industrial standard micrometer, with an adjustment accuracy of up to 0.001mm; and the PDC tooth clamping device with bevel and the self-locking pad can be used together to ensure that the cutting depth of the PDC cutting teeth is always constant during the experiment.

[0041] (2) The rock breaking device itself can achieve continuous adjustment of the back tilt angle of the PDC cutting teeth from 0 to 15°. With a series of fixed-angle PDC tooth clamping devices (0 to 60°, 10° interval), the back tilt angle of the PDC cutting teeth can be arbitrarily adjusted from 0 to 75°.

[0042] (3) The force sensor is installed behind the rock clamping device, so fixing the rock will not affect the force sensor; at the same time, the force sensor is made of four load cells connected in parallel through a junction box, which effectively expands the sensor range and can accurately monitor the magnitude of the force applied at any position on the rock.

[0043] (4) Through the above structure, the device can adjust parameters such as cutting speed, cutting depth and cutting tooth back angle, and can accurately monitor the cutting force during the experiment, fully meeting the requirements of PDC single tooth cutting rock breaking experiment. Combined with the experimental scheme and analysis process proposed by the device, the change law of key parameters during PDC tooth rock breaking can be fully monitored. At the same time, the rock breaking characteristics can be refined from multiple scales and multiple angles, and the PDC tooth rock breaking mechanism can be revealed in depth. Attached Figure Description

[0044] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0045] Figure 1 A schematic diagram of the structure of a PDC single-tooth rock-breaking experimental device according to an exemplary embodiment of the present invention is shown;

[0046] Figure 2 It shows Figure 1 The diagram shows the internal structure of the casing;

[0047] Figure 3It shows Figure 1 Schematic diagram of the PDC tooth cutting depth adjustment mechanism;

[0048] Figure 4 It shows Figure 3 Schematic diagram of the PDC tooth clamping unit;

[0049] Figure 5 A schematic diagram of the structure of a tilt angle adjustment unit according to an exemplary embodiment of the present invention is shown;

[0050] Figure 6 It shows Figure 1 A schematic diagram of the structure of the lead screw, outer ring, and rotating mechanism.

[0051] Explanation of reference numerals in the attached figures:

[0052] 1-PDC tooth cutting depth adjustment mechanism, 2-rotating handle, 3-control motor, 4-slide rail, 5-metal plate, 6-base, 7-rock clamping mechanism, 8-rock sample, 9-force sensor, 10-adjustment knob, 11-micrometer body, 12-telescopic structure, 13-cutting and rock-breaking device body, 14-connecting bolt, 15-metal pressure plate, 16-spring, 17-PDC tooth clamping unit, 18-fastening bolt, 19-self-locking pad, 20-fixing bolt, 21-metal pressure head, 22-PDC cutting tooth, 23-left side plate, 24-right side plate, 25-rotating screw, 26-locking nut, 27-adjusting component, 28-support plate, 29-fixed shaft, 30-screw, 31-connecting plate, 32-fixed shaft, 33-outer ring, 34-rotating structure. Detailed Implementation

[0053] In the following sections, the PDC single-tooth cutting rock-breaking experimental apparatus and the rock-breaking mechanism analysis method of the present invention will be described in detail with reference to exemplary embodiments.

[0054] It should be noted that terms such as "first," "second," and "third" are merely for ease of description and distinction, and should not be interpreted as indicating or implying relative importance. Terms such as "up," "down," "left," "right," "inner," and "outer" are merely for ease of description and to establish relative orientations or positional relationships, and do not indicate or imply that the component referred to must have that specific orientation or position.

[0055] In a first exemplary embodiment of the present invention, the PDC single-tooth cutting rock-breaking experimental device mainly includes a cutting rock-breaking device body, a PDC tooth cutting depth adjustment mechanism, a cutting speed adjustment mechanism, and a cutting force measurement mechanism.

[0056] The cutting speed adjustment mechanism includes a housing, a control motor, a slide rail, a base, and a rock clamping mechanism. The housing is horizontally positioned on a plane (e.g., the ground), and the slide rail is positioned along the length of the housing on its upper surface. The housing can be rectangular, and two slide rails are arranged parallel to each other on the left and right sides of the upper surface of the rectangular housing. The base is axially movable along the slide rails, and the rock clamping mechanism is fixedly mounted on the base, used to clamp the rock sample. The control motor is mounted on the housing and drives the base and the rock clamping mechanism to move axially along the slide rails at a predetermined speed, thereby controlling the cutting speed of the rock sample.

[0057] The rock-breaking device body is horizontally positioned above the housing, and is used to fix and mount the PDC tooth cutting depth adjustment mechanism. The PDC tooth cutting depth adjustment mechanism can clamp the PDC cutting teeth and precisely adjust their inclination angle and cutting depth. A cutting force measuring mechanism is mounted on the base and located on the side of the rock sample furthest from the PDC cutting teeth. This mechanism can monitor the magnitude of the cutting force applied to the rock sample. For example, if the rock sample is a cuboid or cube, and the PDC cutting teeth cut from the right side of the rock sample, the force measuring mechanism is located on the left side of the rock sample.

[0058] In this exemplary embodiment, the experimental apparatus may further include a support plate, which is fixedly disposed on the left and right sides of the housing and disposed opposite to each other, and the rock-breaking device body is horizontally disposed on the top of the support plate.

[0059] In this exemplary embodiment, the PDC tooth cutting depth adjustment mechanism includes a micrometer, a metal pressure plate, a spring, a connecting bolt, and a PDC tooth clamping mechanism.

[0060] The cutting and rock-breaking device body is also provided with a mounting groove. For example, the mounting groove can be located below the horizontal plate of the cutting and rock-breaking device body and fixedly connected to the horizontal plate, and the structure of the mounting groove matches the PDC tooth clamping mechanism. The metal pressure plate is horizontally set and located above the mounting groove, and the metal pressure plate has screw holes. The PDC tooth clamping mechanism is vertically set in the mounting groove and its upper end passes through the mounting groove. The connecting bolt is vertically set in the screw hole and its lower end is fixedly connected to the upper end of the PDC tooth clamping mechanism.

[0061] A micrometer is vertically positioned, with its lower end fixedly connected to the upper end of the connecting bolt. The position of the connecting bolt in the bolt hole can be adjusted using the micrometer. One end of the spring is connected to a metal pressure plate, and the other end is connected to a mounting groove on the body of the rock-cutting device. Here, the mounting groove may consist of a left side plate and a right side plate arranged opposite to each other.

[0062] In this exemplary embodiment, the PDC tooth clamping mechanism may include a PDC tooth clamping unit, a fastening bolt, a self-locking pad, a fixing bolt, and a metal pressure head.

[0063] The PDC tooth clamping unit has an upper and lower inclined surface on its left side wall. The self-locking pad has an inclined surface that mates with the upper inclined surface. The fastening bolt passes through the left side plate of the mounting groove to fix the self-locking pad to the rock-breaking device body. For example, the angle between the upper inclined surface and the vertical direction can be 10–20°, and the angle between the lower inclined surface and the vertical direction can be 0–60°. The fixing bolt secures a metal pressure head to the PDC tooth clamping unit, which is used to fix the PDC cutting teeth to the PDC tooth clamping unit. Here, the end of the metal pressure head that contacts the PDC teeth has an inclined surface structure parallel to the lower inclined surface.

[0064] In this exemplary embodiment, the micrometer may include an adjustment knob, a micrometer body, and a telescopic structure. The micrometer body is fixedly mounted on the rock-breaking device body. The upper end of the telescopic structure passes through the rock-breaking device body and is connected to the micrometer body, while its lower end is fixedly connected to the upper end of a connecting bolt. The adjustment knob is located on the micrometer body to adjust the telescopic length of the telescopic structure. Additionally, the micrometer body may also be equipped with a display screen to show the displacement adjusted by the micrometer.

[0065] In this exemplary embodiment, the inclination angle of the PDC cutting teeth can be 0 to 75°, the cutting speed can be 1.6 to 230 mm / s, and the cutting depth control accuracy can reach 0.001 mm.

[0066] In this exemplary embodiment, the experimental apparatus may further include a PDC tooth tilt angle adjustment mechanism, which is disposed on the body of the rock-breaking cutting device. A PDC tooth cutting depth adjustment mechanism is disposed on the PDC tooth tilt angle adjustment mechanism, and the PDC tooth tilt angle adjustment mechanism can achieve a tilt angle adjustment of 0 to 15°.

[0067] In this exemplary embodiment, the PDC tooth back tilt angle adjustment mechanism may include a rotary handle, a rotary screw, a locking nut, and an adjusting member. The cutting and rock-breaking device body has a first opening and a fixed shaft; the adjusting member has a second opening and an adjusting hole; the rotary screw is vertically disposed in the first opening; the locking nut is sleeved on the rotary screw and located below the cutting and rock-breaking device body; the rotary handle is sleeved on the rotary screw and located above the cutting and rock-breaking device body; and an adjusting head is disposed at the lower end of the rotary screw, the adjusting head being movable within the adjusting hole to allow the adjusting member to rotate relative to the fixed shaft.

[0068] In this exemplary embodiment, the cutting force measuring mechanism may include a metal plate and a plurality of force sensors disposed on the metal plate, wherein the metal plate is disposed parallel to the side of the rock clamping mechanism.

[0069] Figure 1 A schematic diagram of the structure of a PDC single-tooth rock-breaking experimental device according to an exemplary embodiment of the present invention is shown; Figure 2 It shows Figure 1 The diagram shows the internal structure of the casing; Figure 3 It shows Figure 1 Schematic diagram of the PDC tooth cutting depth adjustment mechanism; Figure 4 It shows Figure 3 Schematic diagram of the PDC tooth clamping unit; Figure 5 A schematic diagram of the structure of a tilt angle adjustment unit according to an exemplary embodiment of the present invention is shown; Figure 6 It shows Figure 1 A schematic diagram of the structure of the lead screw, outer ring, and rotating mechanism.

[0070] In a second exemplary embodiment of the present invention, as Figure 1 and 2 As shown, the PDC single-tooth cutting rock-breaking experimental device mainly includes the cutting rock-breaking device body, the PDC tooth cutting depth adjustment mechanism, the cutting speed adjustment mechanism, and the cutting force measurement mechanism.

[0071] The cutting speed adjustment mechanism includes a housing ( Figure 1 The housing consists of a control motor 3 (not marked), a slide rail 4, a base 6, and a rock clamping mechanism 7. The housing is horizontally positioned on a plane (e.g., the ground), and the slide rail 4 is positioned along the length of the housing on its upper surface. The housing can be rectangular, and two slide rails are arranged parallel to each other on the left and right sides of the upper surface of the rectangular housing. The base 6 is axially movable on the slide rail 4, and the rock clamping mechanism 7 is fixedly mounted on the base 6. The rock clamping mechanism is used to clamp the rock sample 8. The control motor 3 is mounted on the housing and drives the base 3 and the rock clamping mechanism 7 to move axially along the slide rail at a predetermined speed, thereby controlling the cutting speed of the rock sample.

[0072] The cutting and rock-breaking device body 13 is horizontally positioned above the housing, and is used to fix and support the PDC tooth cutting depth adjustment mechanism. Here, the PDC tooth cutting depth adjustment mechanism can clamp the PDC cutting teeth and precisely adjust their inclination angle and cutting depth.

[0073] The cutting force measuring mechanism is mounted on the base 6 and located on the side of the rock sample 8 away from the PDC cutting teeth. The cutting force measuring mechanism can monitor the magnitude of the cutting force applied to the rock sample. For example, when the rock sample is a cuboid or cube, and the PDC cutting teeth cut from the right side of the rock sample, the force measuring mechanism is located on the left side of the rock sample.

[0074] In this exemplary embodiment, as Figure 1 As shown, the experimental device may also include a support plate 28, which is fixedly installed on the left and right sides of the shell and is arranged opposite to each other. The cutting and rock breaking device body 13 is horizontally installed on the top of the support plate.

[0075] In this exemplary embodiment, as Figure 3 As shown, the PDC tooth cutting depth control mechanism includes a micrometer, a metal pressure plate 15, a spring 16, a connecting bolt 14, and a PDC tooth clamping mechanism.

[0076] The cutting and rock-breaking device body 13 is also provided with a mounting groove. For example, the mounting groove can be located below the horizontal plate of the cutting and rock-breaking device body 13 and fixedly connected to the horizontal plate. The structure of the mounting groove matches the PDC tooth clamping mechanism. The metal pressure plate 15 is horizontally arranged and located above the mounting groove, and a screw hole is opened on the metal pressure plate. The PDC tooth clamping mechanism is vertically arranged in the mounting groove, and its upper end passes through the mounting groove. The connecting bolt 14 is vertically arranged in the screw hole, and its lower end is fixedly connected to the upper end of the PDC tooth clamping mechanism. The micrometer is vertically arranged, and its lower end is fixedly connected to the upper end of the connecting bolt. The position of the connecting bolt in the screw hole can be adjusted by the micrometer. One end of the spring is connected to the metal pressure plate, and the other end is connected to the mounting groove on the cutting and rock-breaking device body. Here, as shown... Figure 3 As shown, the mounting slot may consist of a left side plate 23 and a right side plate 24 arranged opposite to each other.

[0077] In this exemplary embodiment, as Figure 3 As shown, the PDC tooth clamping mechanism may include a PDC tooth clamping unit 17, a fastening bolt 18, a self-locking pad 19, a fixing bolt 20, and a metal pressure head 21.

[0078] The PDC tooth clamping unit 17 has an upper and lower inclined surface on its left side wall, and the self-locking pad 19 has an inclined surface that mates with the upper inclined surface. Fastening bolts 18 pass through the left side plate 23 of the mounting groove to fix the self-locking pad 19 to the rock-breaking device body. For example, as... Figure 4As shown, the angle α between the upper inclined plane and the vertical direction can be 10–20°, and the angle β between the lower inclined plane and the vertical direction can be 0–60°. The fixing bolt 20 fixes the metal pressure head 21 to the PDC tooth clamping unit 17. The metal pressure head 21 is used to fix the PDC cutting teeth 22 to the PDC tooth clamping unit 17. Here, the end of the metal pressure head that contacts the PDC teeth has an inclined plane structure parallel to the lower inclined plane.

[0079] In this exemplary embodiment, as Figure 3 As shown, the micrometer may include an adjustment knob 10, a micrometer body 11, and a telescopic structure 12. The micrometer body 11 is fixedly mounted on the rock-breaking device body 13. The upper end of the telescopic structure 12 passes through an opening in the rock-breaking device body 13 and connects to the micrometer body 11. The lower end of the telescopic structure is fixedly connected to the upper end of a connecting bolt 14. The adjustment knob 10 is located on the micrometer body 11 to adjust the telescopic length of the telescopic structure 12. The micrometer body 11 may also be equipped with a display screen to show the displacement of the micrometer adjustment.

[0080] In this exemplary embodiment, the inclination angle of the PDC cutting teeth can be 0 to 75°, the cutting speed can be 1.6 to 230 mm / s, and the cutting depth control accuracy can reach 0.001 mm.

[0081] In this exemplary embodiment, the experimental apparatus may further include a PDC tooth tilt angle adjustment mechanism, which is disposed on the body of the rock-breaking cutting device. A PDC tooth cutting depth adjustment mechanism is disposed on the PDC tooth tilt angle adjustment mechanism, and the PDC tooth tilt angle adjustment mechanism can achieve a tilt angle adjustment of 0 to 15°.

[0082] In this exemplary embodiment, as Figure 5 As shown, the PDC tooth back tilt angle adjustment mechanism may include a rotary handle 2, a rotary screw 25, a locking nut 26, and an adjusting member 27. The cutting and rock-breaking device body 13 is also provided with a first opening and a fixed shaft 29. The adjusting member 27 is provided with a second opening and an adjusting hole. The rotary screw 25 is vertically disposed in the first opening. The locking nut 26 is sleeved on the rotary screw 25 and located below the cutting and rock-breaking device body 13. The rotary handle is sleeved on the rotary screw and located above the cutting and rock-breaking device body. An adjusting head is provided at the lower end of the rotary screw, and the adjusting head can move within the adjusting hole to allow the adjusting member to rotate relative to the fixed shaft 29.

[0083] In this exemplary embodiment, as Figure 1 As shown, the cutting force measuring mechanism may include a metal plate 5 and a plurality of force sensors 9 disposed on the metal plate, with the metal plate 5 arranged parallel to the left side of the rock clamping mechanism.

[0084] Specifically, such as Figures 1-6 As shown, the working principle of the PDC single-tooth cutting rock-breaking experimental device of the present invention is as follows:

[0085] During the experiment, the rock sample 8 is fixed by the base plate 6 and the rock clamping mechanism 7. Since the force sensor 9 is located on the left side of the rock clamping mechanism, the left and right baffles of the rock clamp can be fully clamped and the rock sample 8 is securely fixed without affecting the force sensor 9. The force sensor 9 can be composed of four load cells connected in parallel via a junction box, expanding the weighing range of the load cells without increasing the output voltage. Furthermore, because the four load cells are evenly placed behind the left baffle of the rock clamping mechanism, the force applied at any position on the rock can be accurately monitored, thus accurately measuring the cutting force.

[0086] During the experiment, the speed of the rock sample 8 on the slide rail 4 was controlled by changing the rotation speed of the control motor 3. Throughout the process, the PDC cutting teeth 22 remained stationary, facilitating focusing when the high-speed camera recorded the rock crushing process. The PDC tooth cutting depth was achieved through the PDC tooth cutting depth adjustment mechanism 1, with an adjustment accuracy of up to 0.001 mm, ensuring a constant cutting depth during the experiment. By rotating the handle 2 in conjunction with a series of fixed-angle PDC tooth clamping units 17, the back tilt angle of the PDC cutting teeth could be arbitrarily adjusted within the range of 0–75°. The specific implementation method will be detailed below.

[0087] The PDC tooth cutting depth adjustment mechanism mainly includes a micrometer (made of...) Figure 3 The micrometer consists of a central adjustment knob 10, a micrometer body 11, and a telescopic structure 12; a metal pressure plate 15; and a PDC toothed clamping mechanism (composed of...). Figure 2 The unit consists of a PDC tooth clamping unit 17, a fixing bolt 20 and a metal pressure head 21, a spring 16, a connecting bolt 14, a fastening bolt 18 and a PDC cutting tooth 22.

[0088] Before the experiment, a suitable PDC tooth clamping mechanism was selected according to the parameter settings, and the PDC tooth back tilt angle β was changed during the experiment. After the PDC cutting tooth 22 was installed, the metal pressure head 21 was fully contacted with the PDC cutting tooth by adjusting the fixing bolt 20, and the PDC cutting tooth 22 was fixed on the PDC tooth clamping unit 17. Then, the PDC tooth clamping unit 17 and the self-locking pad 19 were passed through the gap between the left side plate 23 and the right side plate 24 of the mounting groove of the cutting device body in a bottom-up order. The metal pressure plate 15 and the PDC tooth clamping unit were connected together by the connecting bolt 14, and the tightness of the connecting bolt 14 was adjusted so that the spring 16 was in a slightly compressed state. Throughout the process, the fastening bolt 18 was kept in the open state, so that the PDC tooth clamping unit 17 and the self-locking pad 19 could move freely in the mounting groove. Since the elastic force generated by the spring 16 can balance the weight of the PDC tooth clamping unit, the PDC tooth clamping unit can remain fixed in its original position.

[0089] During the experiment, the micrometer body 11 was fixed to the rock-breaking device body 13 with epoxy resin to ensure that the micrometer body did not move. After the rock sample 8 was clamped, the adjustment knob 10 was rotated to control the telescopic structure 12 to move up and down. Under the action of the spring 16, the PDC tooth clamping unit 17 moved up and down together. When the PDC cutting tooth 22 contacted the upper surface of the rock sample 8, the micrometer reading was zeroed. Then the rock sample was removed, and the adjustment knob 10 was rotated again to make the PDC tooth clamping unit 17 continue to move downward. At this time, the micrometer reading was the cutting depth of the PDC cutting tooth 22. After the adjustment was completed, the fastening bolt 18 was fully tightened to ensure that the self-locking pad 19 was in full contact with the PDC tooth clamping unit 17.

[0090] In the PDC single-tooth rock-breaking experiment, the PDC cutting tooth 22 is mainly subjected to an upward component force. However, due to the mating geometry between the self-locking pad 19 and the PDC tooth clamping unit 17, the upward space of the PDC tooth clamping unit 17 is reduced, thus preventing it from moving upward. Simultaneously, the elastic force generated by the spring 16 and the frictional force on the PDC tooth clamping unit are sufficient to balance its own weight. Therefore, the PDC tooth clamping unit 17 also cannot move downward. This means the PDC tooth cutting depth can be precisely controlled (accuracy up to 0.001 mm) and remains constant throughout the experiment, fully ensuring experimental accuracy.

[0091] PDC tooth back tilt angle adjustment device, such as Figure 5As shown in the diagram. Before the experiment begins, the locking nut 26 is rotated to create a certain distance between it and the PDC tooth cutting rock-breaking device body 13. At this time, the rotating screw 25 is moved up and down by rotating the handle 2, causing the adjusting component 27 to rotate along the fixed shaft 29, thereby rotating the PDC tooth cutting depth adjusting mechanism 1 itself by a certain angle, making it form a certain angle with the horizontal plane. During the adjustment process, the angle of rotation of the adjusting component 27 can be determined in real time by the angle measuring device. After the adjustment is completed, the locking nut 26 is rotated to fix the rotating screw 25, ensuring that the adjusting component 27 itself does not rotate during the experiment. The rotation angle can be adjusted within the range of 0 to 15° by this mechanical structure. With the help of a series of fixed-angle PDC tooth clamping units 17, the back tilt angle β can be varied within the range of 0 to 60°, with each change interval of 10°, ultimately achieving arbitrary adjustment of the back tilt angle within the range of 0 to 75°.

[0092] Depend on Figure 2 and Figure 6 As shown, during the experiment, the control motor 3 rotates, and through the cooperation of the fixed shaft 32 and the lead screw 30, the rotational motion is converted into linear motion. This linear motion is then driven by the connecting plate 31, causing the base 6 to move linearly, thus moving the rock sample 8 towards the PDC cutting teeth to conduct a single-tooth rock-breaking experiment. The fixed shaft 32 is bolted to the outer ring 33, and ball bearings are filled between the rotating structure 34 and the outer ring 33, allowing the outer ring 33 to remain stationary while the control motor 3 drives the rotating structure 34 to rotate. Simultaneously, the inner ring of the rotating structure 34 is connected to the lead screw 30 via a matching thread, thereby converting the rotational motion of the rotating structure 34 into the linear motion of the lead screw 30.

[0093] In a third exemplary embodiment of the present invention, the PDC single-tooth cutting rock-breaking mechanism analysis method includes the following steps:

[0094] Before the experiment begins, set parameters such as depth of cut, cutting speed, and rake angle;

[0095] During the experiment, the fluctuation pattern of cutting force was monitored, and a high-speed camera was used to record the dynamic rock crushing process in real time.

[0096] After the experiment, the collected rock fragments were sieved using sieves of different mesh sizes. The mass of different groups of rock fragments was determined and their mass fraction was calculated. Based on the distribution pattern of the rock fragments, the plastic-brittle fracture mode of the rock was preliminarily determined.

[0097] In this exemplary embodiment, the method may further include:

[0098] The coordinate values ​​at different locations on the cutting groove surface are determined, the rock crushing volume is calculated, and the rock crushing specific energy is determined by combining the average cutting force. At the same time, the surface roughness of the cutting groove is calculated to further determine the rock ductile-brittle crushing mode.

[0099] In this exemplary embodiment, the method may further include:

[0100] After the three-dimensional morphology analysis of the rock was completed, core samples were taken from the center of the cutting groove to observe the distribution characteristics of microcracks on the surface of the core and determine the micro-damage characteristics of the rock during the PDC tooth breaking process. At the same time, rock samples were cut at different locations along the cutting groove and thoroughly polished to make cast thin sections to observe the distribution pattern of microcracks at the bottom of the cutting groove and determine the internal damage characteristics of the rock during the PDC tooth breaking process.

[0101] Specifically, in order to further reveal the rock-breaking mechanism of PDC teeth, a specific experimental and analytical procedure was developed based on the above-mentioned device. The specific steps are as follows:

[0102] 1. Before the experiment, based on the experimental apparatus mentioned in this invention, the cutting depth, rake angle, and cutting speed of the PDC tooth were set according to the experimental plan. The rake angle of the PDC tooth was set using a micrometer adjustment knob, and the cutting depth was kept constant during the experiment by using a locking nut and a self-locking pad. The rake angle of the PDC tooth was adjusted using a suitable PDC tooth clamping unit and a rotating handle, and the rake angle was kept constant during the experiment by tightening the nut; the specific adjustment method has been detailed above. Simultaneously, the cutting speed was controlled by adjusting the rotation speed of the control motor.

[0103] 2. During the PDC tooth cutting and rock-breaking experiment, the cutting force is monitored and collected in real time by a force sensor, and the dynamic rock breaking process is recorded in real time by a high-speed camera. Since the PDC tooth remains stationary during the rock-breaking process, the high-speed camera can be focused on the PDC tooth. During the experiment, there is no need to move the high-speed camera and the focal length remains constant, which facilitates real-time recording of the dynamic rock breaking process.

[0104] 3. After the experiment, the rock debris generated during the experiment was classified using standard mesh sieves (usually 10, 20, 40, and 80 mesh). The mass of different groups of rock debris was weighed using an electronic balance, and the corresponding mass fraction was calculated. The specific calculation method is shown in formula (1):

[0105]

[0106] In the public notice (1) M i The values ​​represent the specific mass of different groups of rock cuttings, in grams; ω represents the mass fraction.

[0107] 4. Subsequently, the three-dimensional coordinate values ​​at different locations in the rock fracture area were measured using a three-dimensional surface topography scanner. The rock fracture volume was calculated based on the integration principle, and the PDC tooth rock breaking specific energy was obtained by combining the average cutting force. At the same time, the surface roughness of the rock fracture area was calculated to evaluate the rock ductile-brittle fracture mode. The rock fracture volume, rock breaking specific energy, and rock surface roughness were determined by formulas (2), (3), and (4), respectively.

[0108] V=∫∫(Z0-Z(x, y))dxdy (2)

[0109]

[0110]

[0111] In equation (2), V is the volume of rock fragmentation, in mm. 3 Z0 is the average height of the undamaged area of ​​the rock surface, in mm; determined by the Z coordinate in the three-dimensional coordinate system, Z(x, y) is the Z coordinate of the data point in the rock fracture area. In equation (3), MSE is the rock fracture specific energy, in MPa; F is the average cutting force, in N; L is the PDC tooth cutting distance, in mm. In equation (4), Ra is the rock surface roughness, in mm; A is the rock area in the fractured region, in mm². 2 .

[0112] 5. After the analysis, core samples were taken from the fractured rock area, gold-plated, and then the distribution characteristics of microcracks in the fractured area were observed and analyzed using a scanning electron microscope to clarify the evolution law of microscopic damage on the rock surface during the rock breaking process. At the same time, rock samples were cut at different positions along the cutting groove and thoroughly polished to make cast thin sections. The distribution law of microcracks at the bottom of the fractured rock area (cutting groove) was then observed using an optical microscope to clarify the internal damage characteristics of the rock during the PDC tooth rock breaking process.

[0113] 6. Based on the above test results, the rock-breaking efficiency of PDC teeth under different experimental conditions is preliminarily determined by the average cutting force and rock fragmentation specific energy. The rock ductile-brittle fracture mode is determined by combining the cutting force fluctuation characteristics (which can be determined by calculating the standard deviation and variance of the cutting force sampling data), the rock chip distribution pattern, and the surface roughness of the cutting groove. The macroscopic rock fragmentation process (including but not limited to rock crushing and crack dynamic propagation) is determined by frame-by-frame analysis of high-speed camera footage. The evolution of microscopic damage on the rock surface and inside is determined by combining scanning electron microscopy and optical microscopy observations. Based on the above experimental and analytical procedures, the rock fragmentation characteristics can be fully described from multiple scales (macro to micro) and angles (rock surface to rock interior), revealing in depth the rock-breaking mechanism of PDC teeth.

[0114] In summary, the beneficial effects of the present invention include at least one of the following:

[0115] (1) The cutting depth of the PDC cutting teeth can be precisely adjusted by the control of the industrial standard micrometer, with an adjustment accuracy of up to 0.001mm; and the PDC tooth clamping device with bevel and the self-locking pad can be used together to ensure that the cutting depth of the PDC cutting teeth is always constant during the experiment.

[0116] (2) The rock breaking device itself can achieve continuous adjustment of the back tilt angle of the PDC cutting teeth from 0 to 15°. With a series of fixed-angle PDC tooth clamping devices (0 to 60°, 10° interval), the back tilt angle of the PDC cutting teeth can be arbitrarily adjusted from 0 to 75°.

[0117] (3) The force sensor is installed behind the rock clamping device, so fixing the rock will not affect the force sensor; at the same time, the force sensor is made of four load cells connected in parallel through a junction box, which effectively expands the sensor range and can accurately monitor the magnitude of the force applied at any position on the rock.

[0118] (4) Through the above structure, the device can adjust parameters such as cutting speed, cutting depth and cutting tooth back angle, and can accurately monitor the cutting force during the experiment, fully meeting the requirements of PDC single tooth cutting rock breaking experiment. Combined with the experimental scheme and analysis process proposed by the device, the change law of key parameters during PDC tooth rock breaking can be fully monitored. At the same time, the rock breaking characteristics can be refined from multiple scales and multiple angles, and the PDC tooth rock breaking mechanism can be revealed in depth.

[0119] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A PDC single-tooth rock-breaking experimental device, characterized in that, The experimental setup includes a rock-breaking device body, a PDC tooth cutting depth adjustment mechanism, a cutting speed adjustment mechanism, and a cutting force measurement mechanism. The cutting speed adjustment mechanism includes a housing, a control motor, a slide rail, a base, and a rock clamping mechanism, wherein... The housing is horizontally arranged on a plane, and the slide rail is arranged on the upper end face of the housing along the length direction of the housing. The base is movable on the slide rail, and the rock clamping mechanism is able to clamp the rock sample and fix it on the base. The control motor is mounted on the housing and can drive the base and rock clamping mechanism to move axially along the slide rail at a predetermined speed to control the cutting speed of the rock sample. The cutting and rock-breaking device body is horizontally positioned above the shell, and the cutting and rock-breaking device body is used to fix and install the PDC tooth cutting depth adjustment mechanism. The PDC tooth cutting depth adjustment mechanism can clamp the PDC cutting tooth and adjust its inclination angle and cutting depth. The PDC tooth cutting depth adjustment mechanism includes a micrometer, a metal pressure plate, a spring, a connecting bolt, and a PDC tooth clamping mechanism. The rock-breaking device body also has a mounting groove. The metal pressure plate is horizontally positioned above the mounting groove and has a screw hole. The PDC tooth clamping mechanism is vertically positioned in the mounting groove. The connecting bolt is positioned in the screw hole and is fixedly connected to the upper end of the PDC tooth clamping mechanism. The micrometer is vertically positioned, and its lower end is fixedly connected to the upper end of the connecting bolt. One end of the spring is connected to the metal pressure plate, and the other end is connected to the rock-breaking device body. The PDC tooth clamping mechanism includes a PDC tooth clamping unit, fastening bolts, self-locking pads, fixing bolts, and a metal pressure head. The PDC tooth clamping unit has an upper inclined surface and a lower inclined surface on its left side. The self-locking pad has an inclined surface that mates with the upper inclined surface. The fastening bolts pass through the side wall of the mounting groove to fix the self-locking pad to the PDC tooth clamping unit. The fixing bolts fix the metal pressure head to the PDC tooth clamping unit. The metal pressure head is used to fix the PDC cutting teeth to the PDC tooth clamping unit. The micrometer includes an adjustment knob, a micrometer body, and a telescopic structure. The micrometer body is fixedly mounted on the rock-breaking device body. The upper end of the telescopic structure passes through the rock-breaking device body and is connected to the micrometer body, while the lower end is fixedly connected to the upper end of the connecting bolt. The adjustment knob is located on the micrometer body to adjust the telescopic length of the telescopic structure. The cutting force measuring mechanism is mounted on the base and located on the side of the rock sample away from the PDC cutting teeth. The cutting force measuring mechanism is capable of monitoring the magnitude of the cutting force applied to the rock sample.

2. The PDC single-tooth rock-breaking experimental device according to claim 1, characterized in that, The experimental apparatus also includes support plates, which are fixedly installed on the left and right sides of the shell and are arranged opposite to each other. The cutting and rock-breaking device body is horizontally installed on the top of the support plates.

3. The PDC single-tooth rock-breaking experimental device according to claim 1, characterized in that, The PDC cutting teeth have an inclination angle of 0~75°, a cutting speed of 1.6~230mm / s, and a cutting depth control accuracy of 0.001mm.

4. The PDC single-tooth rock-breaking experimental device according to claim 3, characterized in that, The experimental device also includes a PDC tooth tilt angle adjustment mechanism, which is mounted on the rock-breaking device body. The PDC tooth cutting depth adjustment mechanism is mounted on the PDC tooth tilt angle adjustment mechanism, and the PDC tooth tilt angle adjustment mechanism can achieve a tilt angle adjustment of 0~15°.

5. The PDC single-tooth rock-breaking experimental device according to claim 4, characterized in that, The PDC tooth back tilt angle adjustment mechanism includes a rotary handle, a rotary lead screw, a lock nut, and an adjusting component. The rock-breaking cutting device has a first opening and a fixed shaft on its main body, a second opening and an adjustment hole on its adjusting component, a rotating screw vertically disposed in the first opening, a locking nut sleeved on the rotating screw and located below the main body of the rock-breaking cutting device, a rotating handle sleeved on the rotating screw and located above the main body of the rock-breaking cutting device, and an adjusting head disposed at the lower end of the rotating screw, the adjusting head being able to move in the adjustment hole to rotate the adjusting component relative to the fixed shaft.

6. The PDC single-tooth rock-breaking experimental device according to claim 1, characterized in that, The cutting force measuring mechanism includes a metal plate and multiple force sensors mounted on the metal plate. The metal plate is arranged parallel to the side of the rock clamping mechanism.

7. A method for analyzing the rock-breaking mechanism of PDC single-tooth cutting, characterized in that, The method includes the following steps: Before the experiment began, the cutting depth, cutting speed and back rake angle were set using the PDC single-tooth cutting rock-breaking experimental device as described in any one of claims 1 to 6. During the experiment, the fluctuation pattern of cutting force was monitored, and a high-speed camera was used to record the dynamic rock crushing process in real time. After the experiment, the collected rock fragments were sieved using sieves of different mesh sizes. The mass of different groups of rock fragments was determined and their mass fraction was calculated. Based on the distribution pattern of the rock fragments, the plastic-brittle fracture mode of the rock was preliminarily determined.

8. The method for analyzing the rock-breaking mechanism of PDC single-tooth cutting according to claim 7, characterized in that, The method further includes: The coordinate values ​​at different locations on the cutting groove surface are determined, the rock crushing volume is calculated, and the rock crushing specific energy is determined by combining the average cutting force. At the same time, the surface roughness of the cutting groove is calculated to further determine the rock ductile-brittle crushing mode.

9. The method for analyzing the rock-breaking mechanism of PDC single-tooth cutting according to claim 7, characterized in that, The method further includes: After the three-dimensional morphology analysis of the rock is completed, core samples are taken from the center of the cutting groove to observe the distribution characteristics of microcracks on the rock core surface and determine the micro-damage characteristics of the rock during the PDC tooth breaking process. Meanwhile, rock samples were cut and thoroughly polished at different locations along the cutting groove to create thin cast sections. The distribution pattern of microcracks at the bottom of the cutting groove was observed to determine the internal damage characteristics of the rock during the PDC tooth breaking process.

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