Drill rod stress wave reduction device

Abstract

A drill rod stress wave reduction device belongs to the technical field of down-the-hole hammer drilling tools and comprises an upper connector, a semicircular clamp, a spline housing, a spline shaft and a gasket assembly. Wherein the gasket assembly is formed by tightly stacking at least two layers of gaskets, each gasket is made of two or two materials with different wave impedances, the wave impedances of any two adjacent gaskets are different, when stress waves are transmitted to the wave clipping device from the impactor at the lower end, the stress waves can sequentially pass through interfaces with different material wave impedances, and the wave clipping effect is achieved. Incident stress waves can be reflected and transmitted on an interface, and the stress wave peak value and stress wave energy finally transmitted to the upper drill rod are greatly reduced. The stress wave reduction protection device is simple in structure, convenient to install and low in manufacturing cost, the service life of the drill rod is prolonged, the tripping time is shortened, and the drilling efficiency is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of down-the-hole hammer drilling tools, and in particular to a drill rod stress wave reduction device. Background Art

[0002] In recent years, with the gradual depletion of shallow mineral resources and the need to develop new energy resources such as hot dry rocks, there is an urgent need for a new technology that can achieve rapid drilling in hard formations with poor drillability, so as to significantly improve the drilling efficiency of hard rock formations and reduce drilling costs. Studies have shown that for formations with strong abrasiveness and poor drillability, such as granite, the use of high-energy impact crushing can increase the drilling efficiency several times compared to traditional rotary drilling technology.

[0003] However, when a high-energy hydraulic down-the-hole hammer uses huge impact kinetic energy to quickly break rocks, the drill pipe will inevitably be subjected to rebound impact vibration from the drill bit and outer tube. This rebound impact kinetic energy is large and the frequency is high, which leads to a rapid shortening of the working life of the drill pipe. On the one hand, the drill pipe used for down-the-hole hammers is mostly made of high-strength alloy steel, which is expensive; on the other hand, the breakage and damage of the drill pipe will cause a series of serious consequences, affecting the safety, efficiency and cost of drilling operations. Therefore, it is necessary to design a wave-chopping and vibration reduction device for down-the-hole hammers to protect the drill pipe, extend its service life, and reduce the probability of accidents.

[0004] According to stress wave related theory, when stress waves pass through the interface of materials with different wave impedances, reflection and transmission will occur. In particular, when stress waves enter materials with smaller wave impedance from materials with larger wave impedance, part of the stress waves are reflected at the interface, thereby reducing the transmitted stress waves. At the same time, when stress waves are transmitted in elastic or plastic materials, the amplitude of the incident stress wave will gradually decrease as the transmission distance increases due to the absorption of part of the energy by the material. In addition, when stress waves pass through a variable cross-section position during propagation, the peak value of the incident stress wave will also increase or decrease accordingly. Summary of the invention

[0005] The purpose of the present invention is to design a drill rod stress wave reduction device to solve the problem that the service life of the drill rod is reduced under the action of high-energy impact vibration during the existing down-the-hole hammer drilling process.

[0006] A drill pipe stress wave reduction device comprises an upper joint, a semicircular clamp, a spline sleeve, a spline shaft and a gasket assembly;

[0007] One end of the upper joint protrudes outward to form a frustum, and the other end is recessed inward to form a cylindrical portion, and the cylindrical portion is connected to a spline sleeve of the same cylindrical structure through a thread;

[0008] The inner wall of the spline sleeve close to the upper joint is provided with a spline groove;

[0009] The spline shaft comprises a small head section, a transmission section, a middle shaft section, a shoulder section and a large head section, wherein the small head section is provided with a positioning groove, the transmission section is provided with spline teeth adapted to the spline groove, the middle shaft section is used to install a gasket assembly, the shoulder section cooperates with the spline sleeve to limit the gasket assembly, and the large head section is provided with an external thread;

[0010] The spline teeth of the transmission section are meshed and connected with the spline grooves of the spline sleeve, and the semicircular ferrule is arranged in the positioning groove of the small head section and is simultaneously limited by the spline sleeve and the cylindrical part of the upper joint, so that the spline shaft is fixed;

[0011] The upper joint, the spline sleeve and the spline shaft are coaxially arranged, and a liquid flow channel is provided at the frustum portion of the upper joint and the center of the spline shaft;

[0012] The gasket assembly is composed of at least two layers of gaskets tightly stacked together, and the gaskets are made of two or more materials with different wave impedances. When two materials are selected, the two gaskets with different wave impedances are arranged at intervals; when more than two materials are selected, the two or more gaskets with different wave impedances are arranged in the order of increasing wave impedance in the direction away from the upper joint.

[0013] Furthermore, in the gasket assembly, each gasket is set with equal thickness or unequal thickness.

[0014] Furthermore, in the gasket assembly, the two gaskets located at the ends are rounded structure gaskets, and the rest are flat gaskets.

[0015] Furthermore, in the remaining flat washers, each washers has an equal cross-section.

[0016] Furthermore, the frustum portion is provided with an external thread for connecting to an upper drill rod.

[0017] The present invention using the above technical solution can achieve the following beneficial effects:

[0018] 1. Compared with the traditional vibration reduction method that simply relies on material deformation to absorb energy, the present invention mainly reflects part of the stress wave through the mismatch of interface wave impedance, and reflects the stress wave multiple times through multiple interfaces, which can effectively reduce the peak value of the stress wave and effectively protect the matching drill pipe. The entire device deforms slightly during the vibration reduction process, which will not affect the assembly relationship of the various components in the whole set of equipment.

[0019] 2. The protective device of the present invention has no vulnerable structure, and the gasket groups are all flat gaskets fixed with semicircular clips and limited by other components in the clipper. The entire device has a small displacement when subjected to impact and has a longer service life.

[0020] 3. The protective device of the present invention has a simple structure, is easy to install, and has a low manufacturing cost, but can greatly increase the service life of the drill rod matched with the down-the-hole hammer, reduce the time of drilling and drilling, and effectively improve the drilling efficiency.

[0021] 4. Due to the large impact power of the down-the-hole hammer, in order to avoid damage to the drill rod, the supporting drill rod is mostly made of high-strength alloy steel, which is expensive. The use of the protective device of the present invention can increase the service life of the supporting drill rod, thereby reducing the actual use cost of the down-the-hole hammer and further reducing the cost of hard rock drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to understand the present invention and do not constitute limitations of the present invention.

[0023] Figure 1 It is a cross-sectional structural schematic diagram of the present invention;

[0024] Figure 2 for Figure 1 Cross-sectional view along the AA direction.

[0025] In the figure, 1-upper joint, 2-semicircle clamp, 3-spline sleeve, 4-spline shaft, 5-gasket assembly. DETAILED DESCRIPTION

[0026] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0027] like Figure 1 and Figure 2 As shown, a drill pipe stress wave reduction device comprises an upper joint 1, a semicircular clamp 2, a spline sleeve 3, a spline shaft 4 and a gasket assembly 5; the upper joint 1, the spline sleeve 3 and the spline shaft 4 are coaxially arranged, one end of the upper joint 1 protrudes outward to form a frustum, and the frustum is provided with an external thread for connecting with the upper drill pipe, and the other end is recessed inward to form a cylindrical part, and the cylindrical part is connected to the spline sleeve 3 of the same cylindrical structure through a thread, and the outer surface of the cylindrical part is kept flush with the outer surface of the spline sleeve 3 after the connection, and the inner wall of the spline sleeve 3 close to the upper joint 1 is provided with a spline groove, and the inner diameter of the inner wall of this side is smaller than the minimum inner diameter of the cylindrical part, such a structural design makes the end face of the spline sleeve 3 close to the upper joint 1 have a stop function, and can limit the semicircular clamp 2 to lock the spline shaft 4;

[0028] The spline shaft 4 is divided into a small head section, a transmission section, a middle section, a shoulder section and a large head section along the direction away from the upper joint 1, with the diameter change as the boundary, wherein the small head section is provided with a positioning groove for installing the semicircular clamp 2; the transmission section is provided with spline teeth adapted to the spline groove for transmitting torque; the middle section is used to install the gasket assembly 5, and the shoulder section cooperates with the spline sleeve 3 to limit the gasket assembly 5, so that the gasket assembly 5 is tightly installed in the annular gap formed between the spline shaft 4 and the spline sleeve 3; the large head section is provided with an external thread for connecting the lower impactor and the drill bit;

[0029] The spline teeth of the transmission section are meshed with the spline grooves of the spline sleeve 3, the semicircular clamp 2 is sleeved in the positioning groove of the small head section and is limited by the spline sleeve 3 and the cylindrical part of the upper joint 1 at the same time, so that the spline shaft 4 is fixed, and the frustum of the upper joint 1 and the center of the spline shaft 4 are provided with a liquid flow channel;

[0030] The gasket assembly 5 is composed of at least two layers of gaskets stacked tightly, and the gaskets are made of two or more materials with different wave impedances. When two materials are selected, the two gaskets with different wave impedances are arranged at intervals; when more than two materials are selected, the more than two gaskets with different wave impedances are arranged in the order of increasing wave impedance in the direction away from the upper joint 1 or arranged in a cycle; when the stress wave is transmitted from the lower end impactor to the clipper, it will pass through the interfaces with different wave impedances of the materials in turn, and the incident stress wave will be reflected and transmitted at the interface, especially when the incident wave enters the material with smaller wave impedance from the material with larger wave impedance, a part of the incident wave is reflected at the interface, thereby reducing the transmitted stress wave. After the stress wave passes through the multi-layer wave impedance mismatched interface, the stress wave peak value and stress wave energy finally transmitted to the upper drill pipe are greatly reduced. In addition, when the stress wave passes through the clipper, part of the stress wave energy is absorbed by the gasket group, resulting in a further reduction in the stress wave energy finally transmitted to the drill pipe, which effectively protects the drill pipe;

[0031] Among them, in the gasket assembly 5, each gasket can be set with equal thickness or with non-equal thickness;

[0032] Among them, in the gasket assembly 5, each gasket contact surface is finely ground to ensure good contact between the surfaces;

[0033] Among them, in the gasket assembly 5, the two gaskets located at the end are rounded structure gaskets, and the rest are flat gaskets. The reason for this setting is mainly based on the consideration of the convenience of assembly angle. Because the shoulder section and the middle section of the shaft adopt rounded transition, the end of the spline sleeve 3 accommodating the gasket assembly 5 also adopts a rounded transition. The two gaskets located at the end are set as rounded structures, which facilitates smooth installation and matching; equal cross-sections are set between each flat gasket.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should be included in the protection scope of the present invention.

Claims

1. A drill pipe stress wave reduction device, characterized in that: It comprises an upper joint (1), a semicircular clamp (2), a spline sleeve (3), a spline shaft (4) and a gasket assembly (5); One end of the upper joint (1) protrudes outward to form a frustum, and the other end is recessed inward to form a cylindrical portion, and the cylindrical portion is connected to a spline sleeve (3) having the same cylindrical structure via a thread; The inner wall of the spline sleeve (3) close to the upper joint (1) is provided with a spline groove; The spline shaft (4) comprises a small head section, a transmission section, a middle shaft section, a shoulder section and a large head section, wherein the small head section is provided with a positioning groove, the transmission section is provided with spline teeth adapted to the spline groove, the middle shaft section is used to mount a gasket assembly (5), the shoulder section cooperates with the spline sleeve (3) to limit the position of the gasket assembly (5), and the large head section is provided with an external thread; The spline teeth of the transmission section are meshed and connected with the spline grooves of the spline sleeve (3); the semicircular clamp (2) is sleeved in the positioning groove of the small head section and is simultaneously limited by the spline sleeve (3) and the cylindrical portion of the upper joint (1), so that the spline shaft (4) is fixed; The upper joint (1), the spline sleeve (3) and the spline shaft (4) are coaxially arranged, and a liquid flow channel is provided at the frustum portion of the upper joint (1) and the center of the spline shaft (4); The gasket assembly (5) is composed of at least two layers of gaskets tightly stacked together, and the gaskets are made of two or more materials with different wave impedances. When two materials are selected, the two gaskets with different wave impedances are arranged at intervals; when more than two materials are selected, the two or more gaskets with different wave impedances are arranged in the direction away from the upper joint (1) in the order of increasing wave impedances.

2. A drill pipe stress wave reduction device according to claim 1, characterized in that: In the gasket assembly (5), each gasket is arranged with equal thickness or unequal thickness.

3. A drill pipe stress wave reduction device according to claim 1 or 2, characterized in that: In the gasket assembly (5), the two gaskets located at the ends are gaskets with rounded corners, and the rest are flat gaskets.

4. A drill pipe stress wave reduction device according to claim 3, characterized in that: In the remaining flat washers, each washers has an equal cross-section.

5. The drill pipe stress wave reduction device according to claim 1, characterized in that: The frustum portion is provided with an external thread for connecting with an upper drill rod.

6. The drill pipe stress wave reduction device according to claim 1, characterized in that: In the gasket assembly (5), each gasket contact surface is finely ground to ensure good contact between the surfaces.

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