Anchor rod reinforced anchor head structure for underground mine

Abstract

The application discloses an underground mine anchor rod reinforced anchor head structure, which comprises an anchor rod part and an anchor head part, the anchor head part is coaxially and detachably connected with the anchor rod part, a conical guide head, a first taper section, a second taper section and a third taper section are sequentially arranged on the outer wall of the anchor head part from the front end to the anchor rod part, the tapers of the first taper section, the second taper section and the third taper section are sequentially increased, annular steps are arranged between adjacent taper sections and at the tail of the third taper section, a plurality of through anchor holes are arranged on the circumferential surface of each annular step, and all the anchor holes are uniformly distributed along the circumferential direction of the annular step; a spiral engagement groove is arranged on the outer wall surface of the first taper section, the second taper section and the third taper section, the spiral engagement groove spirally extends along the axis of each taper section, and the spiral engagement grooves on adjacent taper sections are in opposite directions; the structure can effectively disperse the concentrated force of the anchor rod under the complex surrounding rock stress, and avoids the fatal defect that the root of the traditional anchor head is prone to breakage.

Description

Technical Field

[0001] This invention relates to the field of high-end mining equipment technology, and in particular to an enhanced anchor head structure for underground mine anchor bolts. Background Technology

[0002] In underground mining, rock bolt support is a core support method for controlling surrounding rock deformation and preventing tunnel collapse. Its anchoring effect directly determines the safety and stability of underground mining operations. As a key component for anchoring the rock bolt to the surrounding rock, the structural design of the anchor head directly affects the magnitude of the anchoring force, the uniformity of stress distribution, and the long-term stability of the rock bolt.

[0003] Currently, the anchor heads used in underground mines mostly adopt a single columnar, conical, or simple multi-tooth structure. These structures have the following defects: First, the contact area between the anchor head and the anchoring agent (resin anchoring agent, cement mortar, etc.) is limited, resulting in insufficient bonding strength. Affected by changes in surrounding rock stress and the development of rock fissures, the anchoring agent is prone to peeling and slippage from the anchor head, leading to a decrease in anchoring force. Second, existing anchor heads are mostly rigid structures, which cannot adapt to slight deformations of the surrounding rock. The stress concentration is obvious, and stress concentration is prone to occur at the root of the anchor head, leading to anchor head breakage or anchor failure. Third, the surface of the anchor head is mostly smooth or has a simple texture design, resulting in weak mechanical interlocking with the surrounding rock. Especially in complex mining environments such as fractured rock layers and weathered rock layers, the anchoring reliability is poor, making it difficult to meet the requirements of high-strength support.

[0004] While some existing technologies address improvements to anchor bolt anchoring structures, they primarily focus on adjusting the prestress of the overall anchor bolt, optimizing the grouting mechanism, or improving components such as the tray and nut. For example, grouting anchor bolts with prestressed components at both ends mainly improve anchoring effectiveness through grouting and upper and lower support devices, without core optimization of the anchor head structure itself. They may simply increase the size of the anchor head without addressing structural innovations in core dimensions such as contact area, stress distribution, and mechanical engagement. Therefore, they cannot fundamentally solve the problems of insufficient anchoring force and poor stability in mining environments. Thus, a novel anchor bolt anchoring head structure is needed that is adapted to the characteristics of surrounding rock in underground mines and can significantly improve anchoring force.

[0005] Existing technologies often focus on adjusting the prestress of the overall anchor bolt, optimizing the grouting mechanism, or improving components such as the tray and nut. They fail to address the core optimization of the anchor head's structure itself, or simply increase its size without achieving structural innovation in core dimensions such as contact area, stress distribution, and mechanical engagement. For example, patent CN2229517Y discloses an expansion-shell type metal anchor head that changes the tooth shape of the expansion shell to a straight tooth shape to increase the bearing area of ​​the borehole wall, reduce the concentrated stress on the borehole wall, and prevent borehole wall damage and expansion shell slippage, thus making the anchor head suitable for softer rocks.

[0006] The shortcomings of current technologies are:

[0007] 1. The limited contact area between the anchor head and the anchoring agent results in insufficient bonding strength, which can easily lead to the anchoring agent peeling off or slipping from the anchor head, resulting in a decrease in anchoring force.

[0008] 2. Existing anchor heads are mostly rigid structures, which cannot adapt to slight deformation of the surrounding rock in underground mines. The stress concentration is obvious, which can easily lead to anchor head breakage or anchor rod failure.

[0009] 3. The anchor head has a simple surface design and weak mechanical interlocking with the surrounding rock. In complex underground mining environments such as fractured and weathered surrounding rock, the anchoring reliability is poor and cannot meet the requirements of high-strength support. Summary of the Invention

[0010] The purpose of this invention is to address the above-mentioned issues by providing an enhanced anchor head structure for underground mine anchor bolts. This structure can effectively disperse the concentrated force of the anchor bolt under complex surrounding rock stress, avoiding the fatal defect of easy breakage at the root of traditional anchor heads.

[0011] The specific solution of the present invention is as follows: an enhanced anchor head structure for underground mine anchor bolts, comprising an anchor rod portion and an anchor head, wherein the anchor head and the anchor rod portion are coaxially and detachably connected as one unit. The outer wall of the anchor head is provided with a conical guide head, a first-stage conical segment, a second-stage conical segment, and a third-stage conical segment sequentially from the front end to the anchor rod portion. The taper of the first-stage, second-stage, and third-stage conical segments increases sequentially. Annular steps are provided between adjacent conical segments and at the tail of the third-stage conical segment. Several through anchor holes are provided on the circumferential surface of each annular step, and all anchor holes are evenly distributed along the circumference of the annular step. Spiral interlocking grooves are provided on the outer wall surfaces of the first-stage, second-stage, and third-stage conical segments. The spiral interlocking grooves extend spirally along the axis of each conical segment, and the spiral interlocking grooves on adjacent conical segments rotate in opposite directions.

[0012] Furthermore, the outer diameter of the annular step in this invention is consistent with the maximum outer diameter of the conical guide head.

[0013] Furthermore, in this invention, the axis of the anchoring hole is arranged perpendicularly to the central axis of the conical guide head at a 90° angle, and the number of anchoring holes is 8, with a hole diameter of 3-5 mm.

[0014] Furthermore, the spiral interlocking groove described in this invention has a trapezoidal cross-section, a groove width of 2-4 mm, and a groove depth of 1.5-3 mm.

[0015] Furthermore, the outer surface of the anchor head in this invention is provided with a wear-resistant and corrosion-resistant coating, the thickness of which is 0.1 to 0.2 mm.

[0016] Furthermore, the anchor rod part described in this invention is composed of three parts: the anchor rod body, the anchor head anchor rod connection part, and the anchor head anchoring section. The front part of the anchor head anchoring section is provided with an external thread, which is connected to the anchor head thread. The anchor head anchor rod connection part connects the anchor rod body and the anchor head anchoring section into one piece by a nut.

[0017] The enhanced anchor head structure of this invention provides a mechanical bonding strength between the anchoring agent and the anchor rod that far exceeds that of a single smooth structure. After the anchoring holes on the annular step are filled with the anchoring agent, a through-type "pin" structure is formed, which fundamentally eliminates the relative slippage between the anchor head and the anchoring agent, and the anchoring force can be increased by more than 30%. The annular step designed between adjacent conical segments can effectively disperse the concentrated force of the anchor rod under complex surrounding rock stress, avoiding the fatal defect of easy breakage at the root of traditional anchor heads. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is a partially enlarged structural diagram of the annular step and anchoring hole in this invention;

[0020] Figure 3 This is a schematic diagram of the anchor rod structure in this invention.

[0021] In the figure: 1—conical guide head, 2—first-stage conical section, 3—second-stage conical section, 4—third-stage conical section, 5—anchor hole, 6—annular step, 7—spiral interlocking groove, 8—anchor rod body, 9—anchor head and anchor rod connection, 10—anchor head and anchoring section. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicating orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of describing the present invention or simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0023] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] See Figures 1-3 This invention relates to an enhanced anchor head structure for underground mine anchor bolts, comprising an anchor rod portion and an anchor head. The anchor head and anchor rod portion are coaxially and detachably integrated. The outer wall of the anchor head, from the front end towards the anchor rod portion, is provided with a conical guide head 1, a first-stage conical segment 2, a second-stage conical segment 3, and a third-stage conical segment 4, with the taper increasing sequentially from the first-stage to the third-stage conical segment. Annular steps 6 are provided between adjacent conical segments and at the tail of the third-stage conical segment. Several through anchor holes 5 are provided on the circumferential surface of each annular step, and all anchor holes are evenly distributed along the circumference of the annular step. Spiral interlocking grooves 7 are provided on the outer wall surfaces of the first-stage, second-stage, and third-stage conical segments. The spiral interlocking grooves extend spirally along the axis of each conical segment, and the spiral interlocking grooves on adjacent conical segments rotate in opposite directions. In this invention, the cross-section of the spiral interlocking groove is trapezoidal, with a groove width of 2–4 mm and a groove depth of 1.5–3 mm. Furthermore, the outer diameter of the annular step in this invention remains consistent with and matches the maximum outer diameter of the conical guide head. Furthermore, the axis of the anchoring hole in this invention is arranged perpendicularly to the central axis of the conical guide head at a 90° angle, and there are eight anchoring holes with a diameter of 3–5 mm. Furthermore, the outer surface of the anchoring head in this invention is provided with a wear-resistant and corrosion-resistant coating, the thickness of which is 0.1–0.2 mm.

[0025] Furthermore, the anchor rod part described in this invention is composed of three parts: the anchor rod body 8, the anchor head anchor rod connection part 9, and the anchor head anchoring section 10. The front part of the anchor head anchoring section is provided with an external thread, which is connected to the internal thread provided in the anchor head. The anchor head anchor rod connection part connects the anchor rod body and the anchor head anchoring section into one piece by a nut.

[0026] When using the anchor head structure of this invention, the entire anchor structure is first inserted into the borehole in the surrounding rock. The conical guide head effectively reduces insertion resistance, facilitating the rapid entry of the anchor head into the bottom of the borehole. Then, an anchoring agent (generally resin anchoring agent or cement mortar) is injected, filling the entire borehole and ensuring full contact with the anchor head. Because the anchor head adopts a multi-stage stepped conical structure—namely, a first-stage conical segment 2, a second-stage conical segment 3, and a third-stage conical segment 4—with the taper of each segment increasing sequentially, it not only increases the contact area with the anchoring agent but also creates a "wedge-shaped" anchoring effect, enhancing the adhesion between the anchor head structure and the anchoring agent. The spiral interlocking groove further increases the contact area between the anchor head and the anchoring agent, and the spiral grooves with opposite directions of rotation between adjacent conical segments form a "bidirectional interlocking," effectively preventing relative sliding between the anchor head and the anchoring agent. The anchoring holes on the annular step are filled with the anchoring agent, forming several structures similar to "anchor pins," further improving the bonding strength.

[0027] When the surrounding rock undergoes slight deformation, the multi-stage stepped conical structure, consisting of primary cone segment 2, secondary cone segment 3, and tertiary cone segment 4, can effectively disperse the stress, prevent stress concentration at the root of the anchor head, and prevent anchor head breakage. The wear-resistant and corrosion-resistant coating can protect the anchor head from erosion by underground humid environments and corrosive media, extend its service life, and ensure long-term anchoring effect.

[0028] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings.

[0029] like Figure 1 As shown, the present invention provides an enhanced anchor head structure for underground mines, including an anchor head connected to the anchor rod. The anchor head is made entirely of high-strength alloy steel to ensure connection strength.

[0030] The anchor head has a multi-stage stepped conical structure, which is divided into a first-stage conical segment, a second-stage conical segment, and a third-stage conical segment from the conical guide head to the rear. The taper of the first-stage conical segment is 6°, the taper of the second-stage conical segment is 12°, and the taper of the third-stage conical segment is 20°. The length ratio of each stage of the conical segment is 3:2:1. The length of the first-stage conical segment is 60mm, the length of the second-stage conical segment is 40mm, and the length of the third-stage conical segment is 20mm. An annular step is formed between adjacent conical segments, and the height of the annular step is 3mm to ensure that the anchor head is subjected to uniform force and avoid stress concentration.

[0031] The outer surfaces of the first-stage, second-stage, and third-stage conical sections are all provided with spiral-shaped interlocking grooves. These grooves extend spirally along the axis of the conical section, with the grooves on the first-stage and third-stage sections rotating clockwise and the grooves on the second-stage section rotating counterclockwise, forming a bidirectional interlocking structure. The cross-section of the spiral-shaped interlocking groove is trapezoidal, with a groove width of 3mm, a groove depth of 2mm, and a helix angle of 18°. This increases the contact area with the anchoring agent and enhances the mechanical interlocking effect, preventing the anchor head from slipping off the anchoring agent.

[0032] The side of the annular step has 8 through anchor holes, but there are actually only 4 anchor holes. One end of each hole is open to the other, so 8 holes are visible on the circumference. The anchor holes are evenly distributed along the axial direction of the annular step, with an included angle of 90° between adjacent anchor holes. The diameter of the anchor holes is 4mm. The anchor holes penetrate the inner and outer sides of the annular step. After the anchoring agent is injected, it enters the anchor holes to form "anchor pins" and improve the bonding strength.

[0033] The outer surface of the anchor head is covered with a wear-resistant and corrosion-resistant coating with a thickness of 0.15mm. The coating is made of epoxy resin and silicon carbide mixture and is applied to the outer surface of the anchor head through a spraying process to improve wear resistance and corrosion resistance, making it suitable for underground mining environments.

[0034] When the anchor head structure of this embodiment is used in underground roadway support, the anchor head and anchor rod are first inserted together into the surrounding rock borehole. The conical guide head guides the anchor head smoothly into the bottom of the borehole. Then, resin anchoring agent is injected. After the anchoring agent fills the borehole, it makes full contact with the outer surface of the anchor head, the spiral interlocking groove, and the anchor hole to form a strong bonding structure. The bidirectional spiral interlocking groove enhances the mechanical interlocking between the anchoring agent and the anchor head. The anchoring agent in the anchor hole forms an "anchor pin," further improving the bonding strength. The multi-stage stepped conical structure disperses the force and avoids anchor head breakage, thereby achieving a significant improvement in anchoring force.

[0035] The enhanced anchor head structure of this invention provides a mechanical bonding strength between the anchoring agent and the anchor rod that far exceeds that of a single smooth structure. After the anchoring holes on the annular step are filled with the anchoring agent, a through-type "pin" structure is formed, which fundamentally eliminates the relative slippage between the anchor head and the anchoring agent, and the anchoring force can be increased by more than 30%. The annular step designed between adjacent conical segments can effectively disperse the concentrated force of the anchor rod under complex surrounding rock stress, avoiding the fatal defect of easy breakage at the root of traditional anchor heads.

Claims

1. An enhanced anchor head structure for underground mine anchor bolts, comprising an anchor bolt portion and an anchor head, wherein the anchor head and the anchor bolt portion are coaxially and detachably connected as one unit, characterized in that: The outer wall of the anchor head is provided with a conical guide head, a first-stage conical segment, a second-stage conical segment, and a third-stage conical segment in sequence from the front end to the anchor rod. The taper of the first-stage conical segment, the second-stage conical segment, and the third-stage conical segment increases sequentially. Annular steps are provided between adjacent conical segments and at the tail of the third-stage conical segment. Several through anchor holes are provided on the circumferential surface of each annular step, and all anchor holes are evenly distributed along the circumference of the annular step. Spiral interlocking grooves are provided on the outer wall surfaces of the first-stage, second-stage, and third-stage conical segments. The spiral interlocking grooves extend spirally along the axis of each conical segment, and the spiral interlocking grooves on adjacent conical segments rotate in opposite directions.

2. The reinforced anchor head structure for underground mine anchor bolts according to claim 1, characterized in that: The outer diameter of the annular step remains consistent with that of the maximum outer diameter of the conical guide head.

3. The underground mine anchor bolt reinforced anchor head structure according to claim 1, characterized in that: The axis of the anchoring hole is arranged perpendicularly to the central axis of the conical guide head at a 90° angle. There are 8 anchoring holes with a diameter of 3-5 mm.

4. The reinforced anchor head structure for underground mine anchor bolts according to claim 1, characterized in that: The spiral interlocking groove has a trapezoidal cross-section, a groove width of 2-4 mm, and a groove depth of 1.5-3 mm.

5. The reinforced anchor head structure for underground mine anchor bolts according to claim 1, characterized in that: The outer surface of the anchor head is provided with a wear-resistant and corrosion-resistant coating with a thickness of 0.1 to 0.2 mm.

6. The reinforced anchor head structure for underground mine anchor bolts according to claim 1, characterized in that: The anchor rod consists of three parts: the anchor rod body, the anchor head anchor rod connection part, and the anchor head anchoring section. The front part of the anchor head anchoring section is provided with an external thread, which is connected to the thread of the anchor head. The anchor head anchor rod connection part connects the anchor rod body and the anchor head anchoring section into one unit by a nut.

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