Holding-up hammer drill rod for impact rock drilling

Abstract

An anvil drill rod for percussion rock drilling includes a first threaded end member and a second threaded end member. The first threaded end piece includes external threads and the second threaded end piece includes internal threads. Each thread includes a plurality of thread grooves having a cross-sectional form of substantially the same shape along its axial extent. Each thread groove is defined by a pair of thread tops, an intermediate thread root, and connected thread flanks. For a certain product category, the inner small diameter of the internal thread is within the range of 59-62 mm. And the outer large diameter of the external thread is within the range of 64 to 67 mm. And the screw pitch is in the range of 29-31 mm. The outer diameter of the drill rod ranges from 80 mm to 100 mm.

Description

Top hammer drill rod for impact rock drilling Technical Field

[0001] This disclosure relates to a top hammer threaded connection drill rod for impact rock drilling. Background Technology

[0002] Top hammer drill pipe systems typically consist of multiple drill pipes, also known as drill tubes, which have corresponding threads. Most commonly, the drill pipe has an external threaded component at one end and an internal threaded component at the other end, allowing multiple drill pipes to be connected to a drill string, thus enabling percussion drilling in rock. Therefore, top hammer drill pipes are tools used to connect drill bits to rock drills for percussion drilling purposes. Drill pipes can be used in various fields such as mining, exploration drilling, and construction.

[0003] Once connected to the rock drill, the rock drill's impact and / or rotational motion is transmitted to the drill bit via the drill pipe. When the drill bit contacts the rock, the rock-breaking force is generated by the rock drill's impact and / or rotational motion. The impact energy is transmitted through the pipe to the ground, through the shoulder behind the external thread, and then through the shoulder at the end of the internal thread.

[0004] To engage drill pipes to drill strings suitable for percussion rock drilling, it is well known that interconnectable trapezoidal threads are used on the end portions of the individual drill pipes. In some examples, one end of the drill pipe will include external threads that are interconnectable with internal threads at the end of the next drill pipe. Alternatively, the two ends of the drill pipes to be engaged are threaded together on a sleeve that is provided with internal threads at both ends.

[0005] To ensure a durable connection, the torque on the threaded joint must be very high to prevent loosening during operation. This torque is transmitted to corresponding forces that affect the respective thread walls of the external and internal threads.

[0006] Drill pipes are subjected to high transient loads during rock drilling operations. Therefore, these loads are also transmitted to the threaded joints of the drill pipe. Well-known problems related to drill pipes include:

[0007] • The external and internal threaded components of the drill pipe are prone to premature failure. The combination of thick internal threaded components and a thin rod body in the background technology leads to vibration friction and lateral forces during use, which may cause premature thread failure.

[0008] • During drilling operations, the straightness of the hole deteriorates. Due to working conditions or equipment limitations, drill rods often need to be connected for extended periods, and hole depths can reach forty meters. Background Art: Drill rods have small diameters, and the large gap between the external and internal threaded components leads to poor hole straightness. The direct result of poor straightness is uneven rock size after blasting, which wastes explosives.

[0009] • Thread failure can occur due to the transmission of force at the threaded ends. When externally threaded and internally threaded components are connected, they rely on the end surface of the externally threaded component to transmit the impact and rotational forces of the rock drill. The small contact area makes it easy for indentations to form on the end surface of the externally threaded component, leading to notch fracture and subsequent thread failure.

[0010] Therefore, the service life of drill pipe is related to the ability of threaded joints (i.e., external and internal threaded components) to resist the loads they are subjected to during operation. For this reason, it is desirable to provide threaded joints with a better ability to resist these loads, thereby extending the service life of the components.

[0011] Conventional trapezoidal threads are disclosed in US 6,196,598 A1 and US 4,687,368 A1. A threaded connector with an inclined thread crest is previously known from US 4,040,756. The thread base of both the internal and external threads has a continuously curved construction.

[0012] WO2012161641 discloses a thread arrangement that solves the aforementioned problems and provides a threaded joint with greater fatigue resistance. The disclosed thread arrangement represents a technology that is easily applied to a wide range of threaded applications in impact rock drilling.

[0013] While the thread arrangement in the background art provides a generally applicable technical solution for improving fatigue resistance, this disclosure is intended to provide further improvements suitable for top hammer drill pipe applications.

[0014] In some cases, drill pipes need to be discarded due to wear on the external threaded components. This is preferred because the drilling operator can see the wear on the external threaded components. When the internal threaded components wear, this may not be visible to the drilling operator, and in the worst case, if the internal threaded components of the drill pipe fail due to fatigue, this could cause the drill string to fall out. Failures to retract the drill string from the borehole may also occur due to difficulties associated with threaded connections, such as difficulty in opening the threaded connection. Summary of the Invention

[0015] The purpose of this disclosure is to provide an improved top hammer drill pipe with improved fatigue resistance and simplified drill string connection components. This purpose is achieved by a top hammer drill pipe as defined in the following disclosure.

[0016] According to an aspect of this disclosure, a top hammer drill pipe for percussion drilling is provided. The top hammer drill pipe includes a first threaded end component and a second threaded end component, wherein the first threaded end component includes an external thread, and the second threaded end component includes an internal thread. Each thread includes a plurality of thread grooves having a substantially identical cross-sectional shape along its axial extension. Each thread groove is defined by a pair of thread crests, an intermediate thread root, and connecting threaded flanks. The minor inner diameter of the internal thread is in the range of 59 to 62 mm. The major outer diameter of the external thread is in the range of 64 to 67 mm. The pitch is in the range of 29 to 31 mm.

[0017] In some examples, the outer diameter of the drill pipe is in the range of 80 to 100 mm.

[0018] In some examples, the minor inner diameter of the internal thread is in the range of 59.0 mm to 61.9 mm.

[0019] In some examples, the outer diameter of the external thread is in the range of 64.0 to 66.9 mm.

[0020] In some examples, the length of the internal thread is greater than the length of the external thread.

[0021] In some examples, the length of the internal thread is in the range of 130 to 150 mm, and the length of the external thread is in the range of 125 to 145 mm.

[0022] In some examples, the first threaded end component and the second threaded end component are connected to a hollow tube having a tubular cross-section and an outer diameter in the range of 80 to 100 mm.

[0023] The drill pipe offers the advantage of rapid interconnection to other drill string components, such as other drill pipes, while ensuring improved fatigue resistance. The drill pipe is designed without reducing its diameter along its length; the thread grooves have a substantially consistent diameter along their length, which provides advantages during manufacturing. Furthermore, the reduction in tension concentration in the corresponding thread root region of the drill pipe is highly beneficial to its service life, as the slight decrease in tension level in this region results in better resistance to fatigue fracture and thus thread failure. In addition, the proposed drill pipe provides improvements related to drill pipe manufacturing, such as reduced production costs.

[0024] Furthermore, contact between the thread crest of the internal thread and the thread root of the external thread can be avoided. Therefore, contact is avoided where maximum tension concentration might occur. Otherwise, such contact could lead to heating in the contact area, where the material might not be hardened and is easily damaged, often resulting in fatigue fracture of the external thread, because the potential tension concentration could occur in very undesirable locations. Attached Figure Description

[0025] Figure 1 discloses a drill rod having external and internal threads according to the present disclosure.

[0026] Figure 2 shows the details of the external thread of the drill pipe.

[0027] Figure 3 shows the details of the internal thread of the drill pipe. Detailed Implementation

[0028] The aspects of this disclosure will be described more fully below with reference to the accompanying drawings.

[0029] In the following text, drill string components will be used as general terms to indicate drill bits, shank adapters, engagement sleeves, and transfer adapters, and can form part of a drill string including the drill pipe claimed herein.

[0030] This disclosure relates to a top hammer drill rod 10 for impact rock drilling, as shown in FIG1. ​​The drill rod 10 includes a first threaded end part 11 and a second threaded end part 13. The first threaded end part 11 includes an external thread, and the second threaded end part 13 includes an internal thread. Each thread includes a plurality of thread grooves having a cross-section of substantially the same shape along its axial extension. Each thread groove is defined by a pair of thread crests, an intermediate thread root, and connecting threaded flanks.

[0031] For a given product category, the minor inner diameter of the internal thread is in the range of 59–62 mm, preferably in the range of 59.0–61.9 mm. For the same product category, the major outer diameter of the external thread is in the range of 64–67 mm, preferably in the range of 64.0–66.9 mm. The pitch is in the range of 29–31 mm. The outer diameter of the drill rod is in the range of 80–100 mm.

[0032] The length of the internal thread is in the range of 130~150 mm, and the length of the external thread is in the range of 125~145 mm.

[0033] The first threaded end component 11 and the second threaded end component 13 are integrally joined to the hollow tube 15 having a tubular cross-section. For a certain product category, the outer diameter is in the range of 80 to 100 mm.

[0034] The first threaded end component 11 and the second threaded end component 13 can be integrally joined to the hollow tube 15 by friction welding. The first threaded end component 11 is joined to the first end of the hollow tube in the first joint 12, and the second threaded end component 13 is joined to the opposite second end of the hollow tube in the second joint 14. The diameter of the hollow tube corresponds to the outer diameter of the hollow tube. The processed components can be hardened before friction welding is performed. Similarly, the hollow tube can be hardened before friction welding is performed. In some examples, the final product is hardened.

[0035] In some examples, the weld point between the first threaded end component and the hollow tube is located 210–250 mm from the front end of the first threaded end component. Similarly, the weld point between the second threaded end component and the hollow tube is located 210–250 mm from the front end of the second threaded end component. Preferably, each weld point is located 225–235 mm from each front end.

[0036] Figure 2 shows details of the first threaded end component 11, and Figure 3 shows details of the second threaded end component 13. The first and second threaded end components are preferably machined from corresponding solid cylinders, the outer diameter of which corresponds to the outer diameter of the drill pipe.

[0037] For the above product categories, the outer major diameter d1 of the external thread is in the range of 64~67 mm, preferably in the range of 64.0~66.9 mm. The inner minor diameter d2 of the internal thread 13 is in the range of 59~62 mm, preferably in the range of 59.0~61.9 mm. For the same product category, the pitch p is in the range of 29~31 mm. The outer diameter D of the drill pipe is in the range of 80~100 mm.

[0038] The first threaded end component 11 has a first impact surface. The external thread is integrally and smoothly engaged to the impact surface by a plurality of arc segments that are at least partially engaged in the transition region 16.

[0039] In the example, three arc segments can be provided in the transition region. For a given product category, the radius of the first arc segment is 3–6 mm, preferably 3 mm, to ensure a smooth transition from the external thread to the transition region. For a given product category, the radius of the second arc segment near the impact surface is 13–16 mm, preferably 14 mm. For a given product category, the radius of the third arc segment is 1.5–3 mm, preferably 2 mm; the third arc segment bridges the gap between the second arc segment and the impact surface.

[0040] The external thread is configured to engage with a complementary internal thread located on a drill string component different from the top hammer drill pipe. Similarly, the internal thread is configured to engage with a complementary external thread located on a drill string component different from the top hammer drill pipe.

[0041] The disclosed threaded joint is used to connect drill pipe threads together for impact drilling. A flushing channel extends axially and continuously inside the drill pipe to deliver a flushing flow to the drill bit.

[0042] Figures 2 and 3 illustrate details of the threaded joint of the drill pipe claimed herein. The external threaded joint comprises multiple threaded ridges with intermediate threaded grooves. The internal threaded joint also comprises multiple threaded ridges with intermediate threaded grooves. Each threaded groove configured to receive the threaded ridges has a substantially equal cross-sectional shape along its extension.

[0043] The minor inner diameter of the internal thread is in the range of 59 to 62 mm, that is, the diameter defined by the thread crest of the internal thread ridge used for the internal thread.

[0044] The outer diameter of the external thread is in the range of 64 to 67 mm, that is, the diameter defined by the thread crest of the external thread ridge used for the external thread.

[0045] The pitch is in the range of 29~31 mm.

[0046] According to the top hammer drill rod disclosed herein, the length of the internal thread is greater than the length of the external thread.

[0047] As clearly shown, each threaded groove has a threaded root, which can present multiple surface portions that intersect each other and have a partially circular shape.

[0048] Appropriately, the relationship between the radius of the corresponding surface portion closest to the thread side and the radius of the central surface portion of the thread root can be about 0.05 to 0.7, preferably about 0.3 to 0.6, and most preferably 0.35 to 0.55.

[0049] Preferably, at least in the surface region adjacent to the threaded side that is not the pressure side, the height of the thread root relative to the thread crest of the thread is configured to be such that, in the event of an angular deviation in the connected threaded joint, contact is established between the adjacent thread crest of the external thread and the thread root of the internal thread, thereby avoiding contact with the thread crest of the internal thread in the surface region adjacent to the second threaded side.

Claims

1. A top hammer drill rod (10) for impact rock drilling, the top hammer drill rod comprising a first threaded end component (11) and a second threaded end component (13), wherein the first threaded end component (11) comprises an external thread, and the second threaded end component (13) comprises an internal thread, wherein each thread comprises a plurality of thread grooves having a cross-sectional shape having substantially the same shape along its axial extension, each thread groove being defined by a pair of thread crests, an intermediate thread root, and connecting threaded flanks, characterized in that, The inner minor diameter of the internal thread is in the range of 59 to 62 mm; the outer major diameter of the external thread is in the range of 64 to 67 mm; and the pitch is in the range of 29 to 31 mm.

2. The top hammer drill rod according to claim 1, characterized in that, The outer diameter of the drill pipe is in the range of 80~100 mm.

3. A top hammer drill rod according to claim 1 or 2, characterized in that Each threaded groove has a threaded root, which presents multiple surface portions that intersect each other and have a partially circular shape.

4. The top hammer drill rod of claim 2, wherein, The inner minimum diameter of the internal thread is in the range of 59.0 mm to 61.9 mm.

5. The top hammer drill rod according to claim 4, characterized in that, The outer diameter of the external thread is in the range of 64.0 to 66.9 mm.

6. The top hammer drill rod according to claim 1, characterized in that, The length of the internal thread is greater than the length of the external thread.

7. The top hammer drill rod according to claim 6, characterized in that, The length of the internal thread is in the range of 130 to 150 mm, and the length of the external thread is in the range of 125 to 145 mm.

8. The top hammer drill rod according to claim 6 or 7, characterized in that, The first threaded end component has a first impact surface, and wherein the external thread of the first threaded end component is integrally and smoothly joined to the first impact surface by a first arc segment, a second arc segment and a third arc segment, wherein the radius of the first arc segment is 3 to 6 mm, the radius of the second arc segment is 13 to 16 mm, and the radius of the third arc segment is 1.5 to 3 mm.

9. The top hammer drill rod according to claim 1, characterized in that, The first threaded end component and the second threaded end component are integrally joined to the hollow tube, which has a tubular cross-section and an outer diameter in the range of 80 to 100 mm.

10. The top hammer drill rod according to claim 9, characterized in that, The first threaded end component and the second threaded end component are integrally joined to the hollow tube by friction welding, wherein the first threaded end component is joined to a first end of the hollow tube in a first joint, and the second threaded end component is joined to the opposite second end of the hollow tube in a second joint.

11. The top hammer drill rod of claim 10, wherein, The welding point of the first part is within a range of 210 to 250 mm from the front end of the first threaded end component, and the welding point of the second part is within a range of 210 to 250 mm from the front end of the second threaded end component.

12. The top hammer drill rod of claim 11, wherein, The corresponding welding point is 225-235 mm away from the corresponding front end.

13. The top hammer drill rod according to claim 1, characterized in that, The external thread is configured to engage with a complementary internal thread arranged on a drill string component different from the top hammer drill pipe.

14. The top hammer drill rod according to claim 1, characterized in that, The internal thread is configured to engage with a complementary external thread arranged on a drill string component different from the top hammer drill pipe.

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