A portable mortar anchor rod combination device

Abstract

The utility model relates to a portable sanding mortar anchor rod combination device, including the drill rod, the impactor and the drill bit that connect in proper order still are equipped with the wall protection casing pipe, the rear end of drill rod connects the output shaft of rotary drive device, the wall protection casing pipe is covered in the outside of drill rod, and the rotation cooperation gap is left between drill rod, the wall protection casing pipe adopts high -strength alloy steel material quality, its front end is equipped with the hard alloy tooth, rear end and the output shaft flange connection of rotary drive device. The utility model is suitable for the occasion that the surface soil cover is thicker or more loose, can effectively avoid the hole collapse, and is helpful to improve work efficiency.

Description

Technical Field

[0001] This utility model relates to a portable mortar-applying anchor bolt assembly device. Background Technology

[0002] Mortar anchors are full-length bonded anchors using cement mortar as the anchoring agent. They are mainly used in tunnel construction and slope protection with intact rock structures. The anchor body often uses ribbed steel bars, which are bonded to the surrounding rock through grouting. The construction of existing mortar anchors usually adopts a step-by-step construction method, including drilling, rebar installation, mortar filling, and anchor forming. For example, Chinese patent document CN115492134A discloses a grouting anchor construction process for shallow slope support, including the following steps: S1: Construction preparation, all materials and equipment used in the construction are on site; S2: Drilling, during drilling, the deviation of the anchor hole position, drilling inclination angle, direction angle error, and hole depth should be strictly controlled; S3: Hole cleaning, the duct is cleaned with pressurized air; S4: Grouting of the anchor hole, the grouting pipe should be inserted to the bottom of the hole, and then withdrawn 5cm to 10cm to start grouting. The grouting pipe is slowly and evenly pulled out as the mortar is injected, so that the hole is filled with mortar; S5: Installation of the anchor, the anchor body is inserted in time after the anchor hole is filled with mortar; S6: Quality inspectors and supervising engineers inspect the constructed anchors. Chinese patent document CN113250721A discloses a construction method for mortar anchor bolts, which involves accurately marking the anchor bolt hole positions according to design requirements; drilling using a pneumatic rock drill; cleaning the hole with high-pressure air; employing single-pipe grouting, directly inserting the grouting pipe into the bottom of the anchor bolt hole, repeatedly pushing the grouting pipe towards the bottom of the hole after grouting begins to force excess water out of the hole; then pulling out the grouting pipe while grouting, preparing to insert the anchor bolt; and promptly placing the anchor bolt after grouting, with additional grouting as needed after the anchor bolt is in place. These existing technologies not only involve numerous steps and are time-consuming, but also, in cases where the surface overburden is thick or loose, the hole is prone to collapse after drilling and drying.

[0003] On the other hand, down-the-hole (DH) drills, especially pneumatic DH drills, can effectively drill anchor bolt holes. For example, Chinese patent document CN116607878A discloses an impactor and a DH drill. The DH drill includes a power head, a drill rod, and an impactor. The drill rod is connected to the output end of the power head, and the end of the drill rod away from the power head is connected to the impactor. The drill bit is mounted on the impactor. The impactor includes an outer sleeve, the rear end of which is connected to a connector, and the front end of which is connected to the drill bit via a ferrule. A distribution rod is fixedly installed inside the outer sleeve and communicates with the high-pressure air passage of the connector. A piston is slidably fitted on the outside of the distribution rod, and an inner sleeve is fitted on the outside of the piston. A first air chamber is formed between the connector, the piston, the inner sleeve, and the distribution rod, and a second air chamber is formed between the drill bit, the piston, the outer sleeve, and the distribution rod. An exhaust channel is provided on the connector, and the piston moves along the axial direction of the distribution rod so that the exhaust channel alternately communicates with the first and second air chambers. Chinese patent document CN114541961A discloses a pneumatic down-the-hole hammer drilling device, including a drill rod, an impactor, and a drill bit. The rear connector of the impactor is fixedly connected to the drill rod, and the impactor's ferrule is connected to the drill bit. The impactor's housing has a slag collection chamber, the opening of which is located on the outer circumferential surface of the housing. The housing also includes a guide plate and a first driving mechanism. The guide plate is located directly above the opening of the slag collection chamber, with one end of the guide plate away from the housing axis inclined downwards. The first driving mechanism is used to drive the guide plate to slide outwards from the outside of the housing or slide inwards into the housing. These prior art techniques can only effectively perform drilling, but do not help prevent hole collapse. Utility Model Content

[0004] The purpose of this invention is to reduce or avoid hole collapse.

[0005] The technical solution of this utility model is: a portable mortar anchor bolt assembly device, including a drill rod, an impactor, and a drill bit (or main drill bit) connected in sequence, and a protective sleeve. The rear end (input end) of the drill rod is connected to the output shaft of a rotary drive device. The protective sleeve is fitted on the outside of the drill rod, with a rotational fit clearance (a small annular gap that allows relative rotation) between the sleeve and the drill rod. The output shaft of the rotary drive device is provided with a protective sleeve connecting flange. The protective sleeve is made of high-strength alloy steel, and its front end is provided with carbide teeth (ring teeth). The rear end is connected to the output shaft flange of the rotary drive device (connected by a flange connection). The carbide teeth are used as a casing drill bit, which is a ring drill bit structure (or ring drill bit).

[0006] Preferably, the width of the rotational fit clearance between the casing and the drill pipe is 3-5 mm.

[0007] Preferably, the output shaft of the rotary drive device is provided with a protective sleeve connecting flange.

[0008] Preferably, the rear end of the drill pipe is connected to the output shaft of the rotary drive device via a fixed coupling or a universal joint.

[0009] Preferably, the drill bit is a cross-shaped impact drill bit.

[0010] Preferably, the drill bit is made of alloy material.

[0011] Preferably, the protective sleeve is a rigid sleeve.

[0012] Preferably, the drill bit has six 45° angled slag discharge holes.

[0013] Preferably, the front end of the impactor is provided with a retaining sleeve for spline connection with the drill bit, and the retaining sleeve and the drill bit (connecting section) are provided with a mutually mating spline structure. A limiting pin can be used to limit the range of motion (forward sliding range) of the drill bit.

[0014] Preferably, the rotary drive device is an electric motor or a pneumatic motor.

[0015] The rotary drive device can be equipped with a transmission device, such as a gear reducer, according to actual needs.

[0016] Preferably, the output shaft of the rotary drive device is provided with an air inlet, and the drill bit is provided with an air outlet.

[0017] Preferably, the impactor and the drill rod (the connection between the two) are connected by a tapered thread.

[0018] Any of the portable mortar-drilling anchor bolt assembly devices disclosed in this utility model can be used to drill anchor bolt holes. After drilling is completed, the connection between the protective sleeve and the drive shaft of the rotary drive device is disconnected, and the portable mortar-drilling anchor bolt assembly device is withdrawn (exited). The protective sleeve is left in place in the anchor bolt hole and permanently retained in the hole.

[0019] Preferably, after drilling to the set depth, the rotation is stopped (the rotation drive device is turned off), and the impactor continues to maintain the impact action for a certain period of time (e.g., 30 seconds) to form a hole bottom enlargement head (e.g., by relying on the impact of the drill bit to increase the hole bottom diameter by 50 mm).

[0020] The impact frequency of the impactor (including continued impact after the rotary drive is turned off) can be 800-1200 times / minute.

[0021] The beneficial effects of this utility model are as follows: Because a protective sleeve is installed, it is retained inside the hole after drilling, effectively preventing and avoiding hole collapse. A connecting flange for the protective sleeve is installed on the rotary drive shaft, allowing for easy connection between the protective sleeve and the rotary drive shaft, facilitating the disassembly of the protective sleeve. Since the protective sleeve is retained in the hole, hole cleaning is unnecessary or virtually unnecessary, and rebar installation and mortar filling are smoother, thereby simplifying the construction process, reducing construction difficulty, and shortening construction time.

[0022] Based on field experiments, compared with traditional processes (existing methods), this utility model has significant advantages such as high hole quality (hole diameter deviation <3%), fast construction efficiency (40% increase in shift progress) and excellent anchoring performance (standard deviation of pull-out force <5KN), and is particularly suitable for slope treatment projects of Class IV-V surrounding rock. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the portable mortar-drilling anchor bolt assembly device of this utility model.

[0024] The markings in the diagram are: 1. Drill bit; 2. Carbide teeth; 3. Casing; 4. Guide ring; 5. Drill rod; 6. Casing connecting flange; 7. Output shaft of rotary drive; 8. Air inlet; 9. Rotary drive; 10. Hydraulic push rod; 11. Fixing ring; 12. Base; 13. Guide mechanism; 14. Impactor; 15. Drill bit sleeve; 16. Air outlet. Detailed Implementation

[0025] See Figure 1 The casing 3 in this device is a rigid casing that fits over the outside of the drill rod (or impact drill rod) 5, with a small gap between them to avoid friction or obstruction of relative movement due to contact. The casing is made of high-strength alloy steel, and its dimensions can be customized according to actual needs. For example, in one embodiment, the casing has a wall thickness of 8 mm and an outer diameter of 168 mm. Carbide teeth 2 are embedded at the front end of the casing, serving as a casing drill bit.

[0026] The front end of the drill rod is connected to a cross-shaped impact drill bit, used as drill bit 1, via an impactor 14. The front end of the impactor is equipped with a ferrule 15 for spline connection with the drill bit. A spline structure mates between the ferrule and the drill bit (connecting section), allowing the drill bit to undergo impact motion relative to the impactor while ensuring the impactor always drives the drill bit to rotate synchronously. In practice, the impact frequency of the impact drill bit can be 800-1200 times / minute. Typically, the anchor bolt body (or anchor bolt) required for construction can be made of HRB500 grade threaded steel (32mm in diameter), with a spiral grouting groove on the surface for easy grouting. A limiting structure (e.g., pin, limiting end face) can be set based on existing technology to restrict the axial movement range of the drill bit relative to the impactor.

[0027] The power system can adopt the power system of a conventional pneumatic down-the-hole drill, using an electric motor or pneumatic motor as the rotary drive device 9, and high-pressure air to provide power for the impactor. The working air pressure can be 1.2-2.5MPa. The impactor can be the existing impactor of a pneumatic down-the-hole drill, using high-pressure air as the impact power.

[0028] The output shaft 7 of the rotary drive can be connected to the drill pipe via a universal joint to adapt to construction conditions.

[0029] Transmission Connection: The output shaft of the rotary drive device can be equipped with a protective sleeve connecting flange 6 for installing a protective sleeve. A matching flange is provided at the rear end of the protective sleeve. The two flanges can be connected by a trapezoidal thread (the thread pitch can be 12mm) for easy disassembly. The protective sleeve connecting flange can be directly installed on the output shaft of the rotary drive device (e.g., fixedly sleeved on the front middle part of the output shaft), or an output cylinder can be installed on the outside of the output shaft. The rear end of the output cylinder is fixedly connected to the output shaft (main body) (e.g., through an annular connector that connects the output shaft and the output cylinder through the inner and outer circles respectively). The protective sleeve connecting flange is fixedly installed at the front end of the output cylinder.

[0030] Maintain a 3-5mm annular gap between the drill pipe and the casing.

[0031] The drill bit is an alloy drill bit with six 45° angled slag discharge holes (diameter can be 20mm) at the front end. The impactor and drill rod (the connection between the two) are connected by a tapered thread (taper can be 1:10). The rear of the impactor can be set as a cylindrical shape with external threads, and the front end of the drill rod has a corresponding internal thread. Properly implementing the fit of various dimensions ensures that the drill bit is positioned in front of the protective sleeve (the annular drill bit structure at the front end) to guarantee the impact crushing effect.

[0032] The drill rod has a hollow structure. An air inlet 8 is provided on the output shaft of the rotary drive device, and an air outlet (air outlet) 16 is provided on the drill bit. The air inlet and air outlet are connected by corresponding channels on the output shaft, drill rod and drill bit. The high-pressure air introduced from the air inlet flows out from the air outlet after the drive impactor is activated, which can blow away impurities at the bottom of the hole.

[0033] A hydraulic push rod (hydraulic cylinder) 10 can be used as a thrust mechanism. The rod body of the hydraulic push rod is fixedly installed on the machine base 12. The front end of the piston rod is connected to the rear end of the rotary drive device, thereby driving the rotary drive device and drill rod to move back and forth. The base of the hydraulic push rod can be threaded onto the frame according to the actual situation. If necessary, a clamp or fixing ring (ring-mounted fixing connector) 11 can be set to realize / enhance the fixing of the cylinder body.

[0034] The rotary drive is linearly connected to the frame surface (guided connection). A guide mechanism (e.g., guide rail and matching structure) 13 can be installed on the frame to restrict the rotary drive to linear movement (e.g., sliding) relative to the frame, thereby enabling the feed and retraction of the drill bit. If necessary, a guide ring (sliding collar) 4 for guiding / restricting the casing can be installed at the front of the frame to restrict the casing to linear sliding only within the guide ring.

[0035] Work process:

[0036] 1) Synchronous drilling stage: After startup, the casing and drill pipe rotate at 20-30 r / min driven by the rotary drive motor, which in turn drives the drill bit and the annular drill bit structure to rotate. The drill bit also impacts the rock formation at a frequency of 15 Hz under the drive of the impactor. Pressurized air (usually with a pressure of 0.8 MPa) used to drive the impactor flows out from the air outlet on the drill bit to remove slag.

[0037] 2) Hole-forming holding stage: After drilling to the set depth / design depth (e.g., 6m), stop rotating and continue the impact action for 30 seconds to form a hole bottom enlargement head (diameter increased by 50mm).

[0038] 3) Anchoring grouting stage: First, disconnect the connection (threaded connection) between the wall casing and the output shaft of the rotary drive device, remove the drill bit and drill rod (including the impactor) from the hole, leaving the wall casing stationary in the hole, and then grout according to the existing method. If appropriate, grouting can also be performed through the hollow channel of the drill rod without removing the drill bit and drill rod. After grouting is completed, only the drill bit, impactor, and drill rod are removed, leaving the wall casing permanently in the hole as a wall protection structure.

[0039] C40 cement grout (water-cement ratio 0.45) can be used for grouting. The grouting pressure should be gradually increased to 2MPa and stabilized for 5 minutes.

[0040] Working principle:

[0041] 1) Dynamic wall protection mechanism: The casing moves synchronously with the drill pipe at a following speed of 0.5m / min (the specific following speed depends on actual needs). The radial stress of the hole wall is balanced in real time through circumferential friction resistance (calculation formula: F=πDLμσn, where μ is taken as 0.25), which reduces the risk of hole collapse by 83%.

[0042] 2) Energy transfer optimization: The dual-medium transmission design is adopted, the impact energy is transmitted in a straight line (transmission efficiency of up to 85%), while the rotational torque is mainly borne by the casing, avoiding energy loss and / or product damage caused by the drill pipe bearing the entire load at the same time in the traditional process.

[0043] 3) Anchoring reinforcement mechanism: A rock penetration depth of 6m (or other suitable depths) allows the anchor rod (anchoring section) to penetrate the strongly weathered layer and enter the moderately weathered rock mass (uniaxial compressive strength > 15MPa). Based on the calculation of τ=0.1σc, the pull-out force coefficient is increased by 1.5 times.

[0044] 4) Time control system: The presence of the casing reduces the hole cleaning time constant from τ1=Kγh² / μ to τ2=Kγh² / (μ+Δμ), where Δμ is the casing friction correction term, thereby reducing the hole cleaning probability from 80% to 15%.

[0045] In an engineering example applying this utility model, a power station slope suffered severe water damage, resulting in a complete collapse and landslide. The exposed slope soil was supported by building loads. The bottom slope was constructed using conventional techniques, and pull-out tests met the design requirement of 60 kN. However, during the anchor bolt construction on the upper slope, the soil conditions differed between the upper and lower slopes. The lower slope consisted of a hard rock layer, with approximately 2 meters of topsoil, followed by 1 meter of weathered porphyry, and then more porphyry at deeper levels. Continuing with conventional techniques would likely result in hole collapse and blockage, with an estimated 80% probability of hole clearing. The proposed solution involved using the device and method of this utility model. Three randomly selected locations were drilled, achieving a 100% hole formation rate on the first attempt. The holes were then cleared, inspected, reinforced with rebar, and grouted. A third-party testing unit conducted pull-out tests, yielding pull-out forces of 88 kN, 86 kN, and 87 kN respectively, with no hole collapse observed in any of the drilled holes.

[0046] Unless otherwise specified, the preferred and optional technical means disclosed in this utility model can be arbitrarily combined to form several different specific embodiments when one preferred or optional technical means is a further limitation of another technical means.

Claims

1. A portable mortar anchor bolt assembly, comprising a drill rod, an impactor, and a drill bit connected in sequence, wherein the rear end of the drill rod is connected to the output shaft of a rotary drive device, characterized in that... It is also equipped with a protective sleeve, which is fitted on the outside of the drill pipe and has a rotational fit clearance with the drill pipe. The protective sleeve is made of high-strength alloy steel, with hard alloy teeth at the front end and connected to the output shaft flange of the rotary drive device at the rear end.

2. The portable mortar-applying anchor bolt assembly device as described in claim 1, characterized in that... The width of the rotational fit clearance between the casing and the drill pipe is 3-5mm.

3. The portable mortar-applying anchor bolt assembly device as described in claim 1, characterized in that... The rear end of the drill pipe is connected to the output shaft of the rotary drive device via a fixed coupling or a universal joint.

4. The portable mortar-applying anchor bolt assembly device as described in claim 1, characterized in that... The drill bit is a cross-shaped impact drill bit.

5. The portable mortar-applying anchor bolt assembly device as described in claim 1, characterized in that... The protective sleeve is a rigid sleeve.

6. The portable mortar-applying anchor bolt assembly device as described in claim 1, characterized in that... The drill bit has six 45° angled slag discharge holes.

7. The portable mortar-applying anchor bolt assembly device as described in claim 1, characterized in that... The front end of the impactor is equipped with a ferrule for spline connection with the drill bit, and the ferrule and the drill bit are provided with a spline structure that cooperates with each other.

8. The portable mortar-applying anchor bolt assembly device as described in claim 1, characterized in that... The rotary drive device is an electric motor or a pneumatic motor.

9. The portable mortar-applying anchor bolt assembly device as described in claim 1, characterized in that... The output shaft of the rotary drive device is equipped with an air inlet, and the drill bit is equipped with an air outlet.

10. The portable mortar-applying anchor bolt assembly device as described in any one of claims 1-9, characterized in that... The impactor and the drill pipe are connected by a tapered thread.

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